Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 02/20/13

AREA FORECAST DISCUSSION

NWS NORTHERN INDIANA

833 PM EST TUE FEB 19 2013

.UPDATE...
PREVIOUS FORECAST IN GOOD SHAPE WITH JUST MINOR TWEAKS MADE TO
EVENING POPS TO ACCOUNT FOR SCATTERED SNOW SHOWERS PERSISTING
ACROSS CENTRAL SECTIONS. TAIL OF UPPER VORT MAX WHICH TRACKED
ACROSS NORTHERN INDIANA LATE THIS AFTERNOON APPEARS TO BE EXISTING
NORTHWEST OHIO AT THIS TIME. A SHEARED VORT MAX ACROSS THE
MID/UPPER MS RIVER VALLEY WILL MOVE INTO THE GREAT LAKES REGION
OVERNIGHT...WITH MUCH DRIER MID LEVEL AIR ASSOCIATED WITH THIS
FEATURE. SOME SMALLER SCALE BANDING NOTED OVER PAST FEW HOURS
ACROSS NORTHERN BERRIEN COUNTY...ALTHOUGH DEPTH OF INSTABILITY
WILL REMAIN FAIRLY SHALLOW WITH LAKE MODIFIED RAP BUFFER SOUNDINGS
SUGGESTING EQUILIBRIUM LEVELS AROUND 6K FT. INTENSITY OF LAKE
EFFECT SNOW SHOWERS SHOULD WANE TOWARD THE 04Z-06Z TIMEFRAME AS
DEEPER MOISTURE PROFILES ERODE...BUT A MORE FAVORABLE NORTHWEST
FETCH AND MAINTENANCE OF SHALLOW INSTABILITY SHOULD ALLOW FOR
CONTINUED LIGHTER LAKE EFFECT SNOW SHOWERS OVERNIGHT. WIND GUSTS
HAVE SUBSIDED EARLY THIS EVENING AS SFC LOW ACROSS SOUTHEAST
ONTARIO FILLS...AND GUSTS TO 20 TO 25 MPH SHOULD PERSIST FOR MUCH
OF THE NIGHT POSSIBLY CREATING SOME PATCHY DRIFTING SNOW CONCERNS
ACROSS SOUTHWEST LOWER MICHIGAN. WILL CONTINUE TO HIGHLIGHT THIS
POTENTIAL WITH AN SPS THROUGH AT LEAST LATE EVENING.

.PREV DISCUSSION... /ISSUED 726 PM EST TUE FEB 19 2013/

AVIATION...
00Z TAFS...WINDS TO SLIGHTLY VEER MORE NORTHWESTERLY TONIGHT WHICH
SHOULD MAINTAIN A FAVORABLE FETCH FOR LAKE EFFECT SNOW SHOWERS TO
CONTINUE TO AFFECT KSBN. WATER VAPOR IMAGERY DEPICTS A FAIRLY
STRONG SHORT WAVE NOW DEPARTING THE AREA WITH A BROADER AND MORE
SHEARED VORTICITY MAXIMUM TRACKING ACROSS THE SOUTHERN GREAT LAKES
REGION OVERNIGHT. THIS FEATURE SHOULD MARK THE LEADING EDGE OF
DRIER MID LEVEL AIR THAT SHOULD TEND TO SUPPRESS INTENSITY OF LAKE
EFFECT SNOW SHOWERS OVERNIGHT. WILL CONTINUE TO CARRY IFR
CONDITIONS AT KSBN THROUGH EARLY EVENING...TRENDING TO MVFR IN
SHOW SHOWERS LATE EVENING AND OVERNIGHT AS INVERSION HEIGHTS
SLOWLY LOWER AND DRIER MID LEVEL AIR ADVECTS IN FROM THE WEST.
WIND GUSTS TO 20 TO 25 KNOTS EXPECTED THROUGH MUCH OF THE
OVERNIGHT...AND THESE WIND GUSTS SHOULD PERSIST INTO WEDNESDAY AS
DIURNAL MIXING OFFSETS GRADUAL WEAKENING OF SFC PRESSURE GRADIENT.
HAVE STILL INCLUDED IMPROVEMENT TO VFR AT KFWA WEDNESDAY
MORNING...ALTHOUGH PRESENCE OF STRONG LOW LEVEL INVERSION STILL
OFFERS SOME LOWER CONFIDENCE ON CIG HEIGHTS IN TERMS OF VFR/MVFR
CRITERIA.

PREV DISCUSSION... /ISSUED 333 PM EST TUE FEB 19 2013/

SHORT TERM.../TONIGHT-WED NGT/

VORT MAX EVIDENT ON WATER VAPOR LOOP MOVG EAST ACROSS THE CWA
THIS AFTN CONTG TO CAUSE SCT SNOW SHOWERS OVER THE AREA...
ENHANCED DOWNSTREAM OF LAKE MICHIGAN IN STRONG LOW LEVEL WESTERLY
FLOW. AS THE SHRTWV MOVES EAST OF THE AREA TONIGHT SNOW SHOWER
ACTIVITY WILL TRANSITION TO PURE LAKE EFFECT. LOW LEVEL FLOW WILL
SLOWLY VEER NW OVERNIGHT STEERING LAKE EFFECT THROUGH SW MI AND
SBN-EKM AREA... WITH CHANCES DIMINISHING SEWD TO ROUTE 30 AND NW
PORTIONS OF NW OH. INVERSION BASED BLO 5KFT WITH GRADUAL MID LEVEL
DRYING SHOULD LIMIT ADDITIONAL SNOW ACCUMS TO 1-2 INCHES IN THE
FAR NW PORTION OF CWA WITH LITTLE OR NO ACCUM OVER THE REST OF THE
AREA. CONTD GRADIENT MIXING AND CLOUD COVER WILL LIMIT TEMP FALLS
OVERNIGHT BUT SW SHOULD SEE SOME CLEARING SO CONTD WITH COLDEST
MINS THERE IN THE SINGLE DIGITS RANGING TO THE LOW TEENS N-NE.

LAKE EFFECT SNOW SHOWERS WILL CONT TO SLOWLY DIMINISH WED AS
LOWERING INVERSION/DRYING CONTS. ADDITIONAL ACCUMS SHOULD BE LESS
THAN AN INCH. THERMAL TROF ALOFT WILL SHIFT EAST OF THE CWA DURING
THE DAY AND WITH SOME SUNSHINE EXPECTED BY AFTERNOON...TEMPS
SHOULD RECOVER INTO THE L-M20S.

HIGH PRESSURE RIDGE WILL BUILD INTO THE AREA WED NIGHT ALLOWING
SKIES TO CLEAR AND WINDS TO BECOME LIGHT AND VARIABLE. GIVEN GOOD
RADIATIONAL COOLING CONDITIONS STAYED CLOSE TO PREV FCST MINS IN THE
10-15 RANGE WHICH WAS GENERALLY AT OR SLIGHTLY BLO COOLEST MOS
TEMPS.

LONG TERM... /THURSDAY THROUGH TUESDAY/

ACTIVE PATTERN WILL PERSIST WITH SEVERAL STRONG WAVES SET TO MOVE
INTO THE SOUTHWESTERN STATES AND EJECT TOWARDS THE REGION. THIS
FIRST UPPER LEVEL WAVE...AND ONE OF GREATEST CONCERN...WILL MOVE
INTO WESTERN TEXAS BY EARLY THURSDAY. 120 KT JET STREAK WILL AID IN
RAPID CYCLOGENESIS WITH THESE FEATURES MOVING NE TOWARDS THE REGION
BY THURSDAY NIGHT. FURTHER STRENGTHENING OF JET STREAK (140 KTS+)
AND LFQ WILL MOVE ACROSS THE AREA HELPING TO DEVELOP A LARGE BAND OF
PRECIP. THE PRECIP SHOULD FALL IN THE FORM OF SNOW FOR MUCH OF
THURSDAY NIGHT WITH ACCUMULATIONS ANTICIPATED...HIGHER SW. NOSE OF
WARM AIR WILL SURGE NORTH LATE THURS NGT INTO FRI...MAINLY IN THE
900 TO 825 MB LAYER. SREF INCREASES TEMPS IN THIS RANGE TO 0 TO +1
C WITH NAM12 A BIT WARMER. THE TRICKY PART WILL BE AS THIS WARM AIR
ARRIVES...THE DEEPEST MSTR AND FORCING WILL BE SHIFTING EAST AND
WEAKENING AS SFC FEATURES RAPIDLY OCCLUDE. AS A RESULT...ANY
FREEZING PRECIP MAY BE IN THE FORM OF FREEZING DRIZZLE...WHICH IF
ROADS ARE SNOW COVERED...WOULD LESSEN IMPACTS. IN ADDITION...MOST
LOCATIONS WILL SEE RISING TEMPS THROUGH THE DAY WITH VALUES INTO THE
MID AND MAYBE UPPER 30S EXCEPT FOR FAR NE SECTIONS WHICH MAY LINGER
NEAR FREEZING AT BEST. HAVE ATTEMPTED TO ADD SOMEWHAT MORE DETAIL
BUT HAVE NOT GOTTEN CARRIED AWAY YET WITH EVENT STILL OVER 2 DAYS
AHEAD.

WITH THE NW AND EVENTUAL E TRACK OF THE FEATURES...NO SIG COLD AIR
WILL ARRIVE. TEMPS SHOULD ACTUALLY MODERATE FURTHER WITH AFTERNOON
HIGHS ADDING A FEW DEGREES EACH DAY INTO EARLY NEXT WEEK WHEN
READINGS WELL INTO THE 40S ARE EXPECTED. NEXT WAVE WILL DROP INTO
THE SW STATES OVER THE WEEKEND AND SIMILAR SETUP FOR CYCLOGENESIS
WILL TAKE PLACE. MODELS VARY ON EXACT TIMING AND CONTRIBUTION FROM
THE GULF BUT SYSTEM COULD END UP FAIRLY WET MONDAY NIGHT INTO
TUESDAY. SFC TEMPS AT THE ONSET MONDAY NIGHT MAY BE NEAR FREEZING
BUT STRONG LL JET SHOULD ALLOW FOR RISING TEMPS OVERNIGHT INTO
TUESDAY. HAVE WENT RAIN DURING MON EVE AND TUESDAY AFTERNOON AND FOR
NOW A RAIN/SNOW MIX OVERNIGHT MON INTO TUES MORNING. FURTHER CHANGES
WILL BE LIKELY WITH LATER FORECASTS.

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST WEDNESDAY FOR LMZ043-
046.

GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LMZ043-046.

SHORT TERM...JT
LONG TERM...FISHER
AVIATION...MARSILI
UPDATE...MARSILI

AREA FORECAST DISCUSSION

NWS INDIANAPOLIS IN

346 PM EST MON FEB 18 2013

.UPDATE...
THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED BELOW

.SYNOPSIS...
ISSUED AT 344 PM EST MON FEB 18 2013

A STRONG LOW PRESSURE SYSTEM MOVING THROUGH THE GREAT
LAKES WILL BRING RAIN TO THE AREA THIS EVENING AND POTENTIAL FOR A
RAIN SNOW MIX AND SOME SNOWFLAKES OVERNIGHT. WINDS WILL REMAIN
STRONG THROUGH TUESDAY WITH A TIGHT PRESSURE GRADIENT OVER THE AREA.
TEMPERATURES WILL DROP QUITE A BIT AFTER THE COLD FRONTAL PASSAGE
OVERNIGHT AND AFTER SOME FLURRIES TUESDAY DRY WEATHER WILL BE IN
PLACE UNTIL THURSDAY. A STRONG LOW PRESSURE SYSTEM ARRIVING THURSDAY
WILL BRING A WINTRY MIX WITH SOME ICE POTENTIAL TO THE AREA THROUGH
THURSDAY NIGHT AND INTO FRIDAY. TEMPERATURES SHOULD MODERATE WITH
THE PASSAGE OF THE THURSDAY SYSTEM.

.NEAR TERM /THIS EVENING AND TONIGHT/...

ISSUED AT 344 PM EST MON FEB 18 2013

/...

RAIN SHOWERS ARE BEGINNING TO MOVE INTO THE NORTHWESTERN COUNTIES AS
SEEN ON 88D RADAR LOOP. LOOKING AT THE MOSAIC RAIN WILL CONTINUE TO
OVERSPREAD THE AREA FROM THE WEST AND SOUTHWEST AS THE AFTERNOON AND
EVENING WEAR ON. WITH A STRONG LOW LEVEL JET AND RAP SHOWING 100-200
J MUCAPE OVER PARTS OF THE AREA THROUGH 3Z WILL LEAVE ISOLATED
THUNDER COUPLED WITH LIKELY OR GREATER POPS. SOUNDINGS ARE SHOWING A
BRIEF PERIOD OF A MIX OF RAIN AND SNOW STARTING AROUND 6Z IN THE
NORTHWESTERN COUNTIES AND WORKING SOUTHEAST FROM THERE...REACHING
CENTRAL PARTS OF THE AREA AROUND 9Z OR SO. PRECIP SHOULD CHANGE OVER
TO ALL SNOW WITHIN AN HOUR OR TWO OF MIXING. WITH DRY AIR ARRIVING
WITH THE COLD AIR BEHIND THE COLD FRONT DO NOT EXPECT MUCH OF
ANYTHING IN THE WAY OF ACCUMULATION ESPECIALLY AS YOU HEAD FURTHER
SOUTHEAST. TOTAL RAINFALL AMOUNTS SHOULD WIND UP ANYWHERE FROM A
QUARTER INCH TO THREE QUARTERS OF AN INCH FOR MOST LOCATIONS.

WINDS SHOULD CONTINUE TO GUST THROUGH THE NIGHT. FOR THE REMAINDER
OF THE AFTERNOON EXPECT GUSTS OF 30-40 MPH. THEY COULD DROP OFF A
LITTLE /TO 20 TO 30 MPH/ TONIGHT AFTER SUNSET AHEAD OF THE FRONT AND
PICK BACK UP AFTER FRONTAL PASSAGE.

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...

ISSUED AT 344 PM EST MON FEB 18 2013

COLD AIR WILL STREAM IN IN THE WAKE OF THE COLD FRONTAL PASSAGE.
THERE MAY BE A STRAY SNOW SHOWER OR TWO LEFT IN THE EAST TO BEGIN
THE DAY TUESDAY AS THE LOW PRESSURE SYSTEM LIFTS NORTHEAST AWAY FROM
THE GREAT LAKES. A TIGHT PRESSURE GRADIENT WILL REMAIN ACROSS THE
AREA AND ANOTHER DAY WITH WIND GUSTS IN THE 30-40 MPH RANGE WILL BE
IN STORE...THIS TIME WITH MUCH COLDER TEMPERATURES ON NORTHWESTERLY
WINDS. ALTHOUGH MEASURABLE SNOW IS NOT ANTICIPATED...WITH THE
PASSAGE OF THE UPPER TROUGH AND COLD AIR ALOFT EXPECT TO SEE SOME
FLURRIES AROUND THE AREA THROUGH THE MORNING HOURS...AND THESE COULD
CONTINUE ACROSS THE NORTH THROUGHOUT THE DAY.

TUESDAY NIGHT EXPECT SKIES TO START CLEARING OUT AND WINDS TO DROP
OFF AS PRESSURE GRADIENT WEAKENS. WITH ALL THE COLD ADVECTION FROM
EARLIER IN THE DAY EXPECT TEMPERATURES TO PLUMMET INTO THE SINGLE
DIGITS TO MID TEENS. WEDNESDAY WILL SEE AMPLE SUNSHINE BUT 850 MB
TEMPERATURES REMAIN COLD. TEMPERATURES WILL STRUGGLE TO REBOUND AND
HIGHS SHOULD MAX OUT IN THE 20S WITH LOW 30S IN THE SOUTH...WHICH
WAS A GUIDANCE AVERAGE. FOR WEDNESDAY NIGHT WARM ADVECTION WILL
BEGIN IN EARNEST BUT SKIES WILL REMAIN MOSTLY CLEAR SO LOWS SHOULD
BE IN THE TEENS TO AROUND 20 WHICH WAS REFLECTED WELL BY THE MODEL
CONSENSUS.

.LONG TERM /THURSDAY THROUGH MONDAY/...

ISSUED AT 246 PM EST MON FEB 18 2013

MAIN FOCUS FOR THE EXTENDED REMAINS ON POTENTIAL FOR A WINTRY MIX
WITH STORM MOVING THROUGH THE REGION THURSDAY AFTERNOON AND
NIGHT WITH CHANCES FOR ADDITIONAL PRECIP RETURNING FOR EARLY NEXT WEEK.

ACTIVE AND AMPLIFIED PATTERN ALOFT SETTING UP THROUGH THE PERIOD.
MODEL GUIDANCE REMAINS GENERALLY CONSISTENT WITH THE MAIN FEATURES
ASSOCIATED WITH LOW PRESSURE TRACKING OUT OF THE CENTRAL PLAINS
AND OCCLUDING OVER THE MID MISSISSIPPI VALLEY EARLY FRIDAY. THE
DETAILS HOWEVER REMAIN MURKY AS THE COMPLICATING FACTORS
PRESENTED BY DRY AIR AND ITS IMPACTS ON PRECIP COVERAGE AND
INTENSITY...AND SURFACE TEMPS AND THEIR IMPACT ON PRECIP TYPE. AS
THE LOW OCCLUDES AND WEAKENS THURSDAY NIGHT...MAJORITY OF THE MODELS
CONTINUE TO ADVERTISE A SPLITTING OF DEEPER MOISTURE TOWARDS THE
UPPER LOW TO THE NORTHWEST AND ALONG THE OCCLUDED FRONT SOUTH OF
THE FORECAST AREA IN THE VICINITY OF A NEW SURFACE WAVE. REMAIN
CONCERNED THAT PRESENCE OF DRY AIR AND PERSISTENT EASTERLY FLOW
AHEAD OF THE FRONT WILL IMPEDE PRECIP ONSET UNTIL THURSDAY
AFTERNOON...AND WILL LIKELY LIMIT PRECIP ACCUMS AS THE LOWER
LEVELS MOISTEN UP.

SOUNDING DATA REMAINS CONSISTENT IN FAVORING LIGHT SNOW AND
POSSIBLY SLEET AS MAIN PRECIP TYPES THROUGH 00Z FRIDAY. SURGE OF
WARMER AIR THROUGH THE BOUNDARY LAYER NOT AS STRONG AND SLOWER
THAN PREVIOUS RUNS INDICATED. TO ACCOUNT FOR THE SLIGHTLY COOLER
BOUNDARY LAYER CONDITIONS... HAVE HELD ONTO SNOW AND SLEET
MENTION OVER NORTHERN COUNTIES THROUGH THE EVENING WITH FREEZING
RAIN DEVELOPING THEREAFTER. PRECIP SHOULD TRANSITION INCREASINGLY
TOWARDS FREEZING RAIN ACROSS THE I-70 CORRIDOR WITH POSSIBILITY
FOR A CHANGE TO ALL RAIN OVER FAR SOUTHERN COUNTIES AS SURFACE
TEMPS REACH AND WARM PAST 32F LATE THURSDAY NIGHT. AMOUNTS REMAIN
GREATLY IN QUESTION DUE TO THE POTENTIAL IMPACTS WITH DRIER AIR
ALOFT AS THE FRONT PASSES...BUT POTENTIAL FOR A LIGHT ICE
ACCUMULATION IS POSSIBLE OVER MUCH OF THE AREA. ALSO COULD
SEE AN INCH OR SO OF SNOW ACCUM OVER NORTHERN COUNTIES.

SURFACE TEMPS WILL WARM ABOVE 32F OVER ENTIRE FORECAST AREA FRIDAY
WITH ANY LINGERING PRECIP FALLING AS LIGHT RAIN AND/OR DRIZZLE.
WILL SEE CLOUDS PERSIST INTO SATURDAY AS A SURFACE WAVE PASSES
TO THE SOUTHEAST OF THE REGION ALONG THE REMNANT FRONT. YET
ANOTHER STRONG UPPER LOW SET TO EJECT OUT INTO THE CENTRAL PLAINS
BY EARLY NEXT WEEK AND LOOKS POISED TO SEND OUT ANOTHER OCCLUDED
SURFACE LOW INTO THE MIDWEST. WILL INTRODUCE LOW CHANCES FOR RAIN
MONDAY. TEMPS WILL BE NEAR TO JUST ABOVE NORMAL OVER THE WEEKEND.

.AVIATION /DISCUSSION FOR THE 182100Z IND TAF UPDATE/...

VFR CONDITIONS ARE EXPECTED TO CONTINUE THE NEXT COUPLE OF HOURS.
RADAR TRENDS SHOW PRECIP SW OF CENTRAL INDIANA QUICKLY MOVING NE
TOWARD THE TAF SITES. THIS IS BEING AIDED BY THE STRONG LLJ THAT
WILL BE PUSHING ACROSS THE AREA THIS EVENING.

AS THE RAIN ARRIVES THIS EVENING MVFR CIGS ARE EXPECTED. ONGOING
TAFS REFLECT THIS WELL.

PREVIOUS DISCUSSION BELOW

/DISCUSSION FOR 181800Z TAF ISSUANCE/...

ISSUED AT 1229 PM EST MON FEB 18 2013

DETERIORATING FLYING CONDITIONS BY THIS EVENING WITH THE ARRIVAL OF
RAIN...WITH A CHANGEOVER TO LIGHT SNOW LATE TONIGHT. MVFR CEILINGS
TO PERSIST THEN THROUGH THE END OF THE FORECAST PERIOD.

WINDY CONDITIONS ALREADY ACROSS THE REGION EARLY THIS AFTERNOON
WITH GUSTS APPROACHING 30KTS...ESPECIALLY AT KBMG AND KHUF. STILL
APPEARS BASED OFF LAPS SOUNDINGS THAT AN INVERSION IS PRESENT IN
THE LOW LEVELS AND IS LIMITING FULL MIXING AND HIGHER WINDS. DO
ANTICIPATE THIS TO DIMINISH OVER THE NEXT COUPLE HOURS WHILE
THICKER CLOUDS BEGIN TO MOVE INTO THE REGION FROM THE SOUTHWEST.
MAY SEE A PERIOD WITH HIGHER GUSTS BEFORE SKIES CLOUD UP BUT HAVE
BACKED OFF JUST A BIT ON FORECAST GUSTS FOR THE AFTERNOON AND AM
HOLDING THEM AROUND 30KTS.

MOST RECENT HRRR DATA SUPPORTIVE OF A SLOWER ONSET TO RAINFALL
WITH PRECIP REACHING THE TERMINALS BETWEEN 21-23Z. GREATEST
COVERAGE TO RAINFALL WILL IMPACT TERMINALS DURING THE EVENING AS
70KT 850MB JET RACES ACROSS THE REGION. CEILINGS WILL LOWER TO
MVFR DURING THE COURSE OF THE EVENING AND PERSIST INTO THE
OVERNIGHT. WINDS ARE LIKELY TO BACK TO S/SE THIS EVENING AS THE
LOW PASSES BY TO THE NORTHWEST...GRADUALLY VEERING TO SOUTHWEST
THEN WESTERLY WITH THE PASSAGE OF THE STRONG COLD FRONT BETWEEN
06-09Z. COLD ADVECTION COMMENCES IMMEDIATELY WITH THE PASSAGE OF
THE FRONT...LIKELY RENEWING STRONGER SUSTAINED WINDS IN EXCESS OF
20KTS WITH GUSTS AT OR ABOVE 30KTS. PASSAGE OF THE FRONT WILL ALSO
USHER IN MUCH COLDER AIR WITH ANY LINGERING PRECIP CHANGING OVER
TO LIGHT SNOW BEFORE ENDING. GUSTY WESTERLY WINDS AT 270-280
DEGREES FOR TUESDAY MORNING WITH MVFR STRATUS REMAINING THROUGH
THE END OF THE FORECAST PERIOD.

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SYNOPSIS...CP
NEAR TERM...CP
SHORT TERM...CP
LONG TERM....RYAN
AVIATION...RYAN/JP

AREA FORECAST DISCUSSION

NWS INDIANAPOLIS IN

343 PM EST MON FEB 18 2013

.UPDATE...
AVIATION SECTIONS UPDATED

.SYNOPSIS...
ISSUED AT 350 AM EST MON FEB 18 2013

A RATHER ACTIVE WEATHER PATTERN WILL BEGIN TODAY AS THE FIRST OF
TWO WEATHER SYSTEMS MOVES INTO CENTRAL INDIANA. WIDESPREAD
RAINFALL AND ISOLATED THUNDERSTORMS WILL MOVE ACROSS THE FORECAST
AREA THIS AFTERNOON AND TONIGHT. DRIER WEATHER WILL FOLLOW AS HIGH
PRESSURE RE-ESTABLISHES ITSELF OVER THE AREA ON TUESDAY NIGHT AND
WEDNESDAY. HOWEVER...IT WILL BE SHORT-LIVED AS YET ANOTHER SYSTEM
MOVES IN ON THURSDAY...THIS ONE BRINGING A WINTRY MIX WITH IT.

.NEAR TERM /REST OF TODAY/...

ISSUED AT 957 AM EST MON FEB 18 2013

UPDATED FORECAST TO PUSH TIMING BACK ON A LITTLE ON THE ARRIVAL OF THE
CLOUDS AND RAIN BASED ON LATEST GUIDANCE FROM RAP/HRRR/NAM12. NOW
LOW CHANCES FOR PRECIP DON/T START UNTIL 20Z IN THE WEST AND
INCREASE FROM THEN ON SPREADING EAST ACROSS THE AREA. KEPT
ISOLATED THUNDER SIMILAR TO PREVIOUS FORECAST BUT ENDED BY 3Z.
FOR TEMPERATURES RAISED HIGHS OVER MOST OF THE AREA BY A DEGREE OR
TWO WITH SUNSHINE AVAILABLE FOR LONGER THAN PREVIOUSLY THOUGHT. AS
FAR AS THE WIND IS CONCERNED FORECAST SOUNDINGS SHOW WINDS VEERING
WITH HEIGHT AND NOT VERTICALLY STACKING. EVEN WITH A 70 KT LOW
LEVEL JET ARRIVING THINK IT WILL BE DIFFICULT TO MIX DOWN THE
HIGHER MOMENTUM VALUES. THUS STILL LOOKS LIKE GUSTS WILL BE
BORDERLINE FOR ADVISORY AT AROUND 40-45 MPH. HIGHEST GUSTS SHOULD
BE IN THE WEST NEAR THE TIGHTER PRESSURE GRADIENT...BUT ULTIMATELY
THINK ONE OR TWO OBSERVATIONS THAT JUST BARELY TAP CRITERIA IS
BETTER COVERED WITH AN SPS. WILL CONTINUE TO MONITOR NEW DATA AS
IT ARRIVES AND CHANGE COURSE IF NECESSARY.

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...

ISSUED AT 350 AM EST MON FEB 18 2013

THE BULK OF PRECIP WILL BE CONFINED TO THE EASTERN PORTIONS OF
CENTRAL INDIANA AFTER TUE 06Z. AT THAT TIME...FORECAST SOUNDINGS
ARE SUPPORTING A TRANSITION TO RAIN/SNOW MIX AND THEN FINALLY ALL
SNOW SHOWERS LATE IN THE NIGHT. HOWEVER...PRECIP WILL EXIT THE
AREA BEFORE ANY SNOW CAN ACCUMULATE...A DUSTING AT BEST.

HIGH PRESSURE WILL MOVE INTO THE AREA TONIGHT BRINGING DRY WEATHER
THROUGH THE REMAINDER OF THE SHORT TERM PERIOD. MODELS HAVE A
HANDLE ON THE COLD ADVECTION FILTERING INTO AREA TONIGHT...SO
STUCK WITH ALLBLEND. TEMPS WILL GRADUALLY FALL INTO THE 20S
TONIGHT AND HAVE A TOUGH TIME REBOUNDING AT ANY POINT DURING THE
SHORT TERM PERIOD DUE TO NORTHWESTERLY WINDS. SIGNIFICANT
RADIATIONAL COOLING AT NIGHT WILL ALLOW TEMPS TO PLUMMET INTO THE
TEENS ONCE AGAIN TOMORROW AND WEDNESDAY NIGHTS.

.LONG TERM /THURSDAY THROUGH MONDAY/...

ISSUED AT 246 PM EST MON FEB 18 2013

MAIN FOCUS FOR THE EXTENDED REMAINS ON POTENTIAL FOR A WINTRY MIX
WITH STORM MOVING THROUGH THE REGION THURSDAY AFTERNOON AND
NIGHT WITH CHANCES FOR ADDITIONAL PRECIP RETURNING FOR EARLY NEXT WEEK.

.AVIATION /DISCUSSION FOR THE 182100Z IND TAF UPDATE/...

AS THE RAIN ARRIVES THIS EVENING MVFR CIGS ARE EXPECTED. ONGOING
TAFS REFLECT THIS WELL.

PREVIOUS DISCUSSION BELOW

/DISCUSSION FOR 181800Z TAF ISSUANCE/...

ISSUED AT 1229 PM EST MON FEB 18 2013

DETERIORATING FLYING CONDITIONS BY THIS EVENING WITH THE ARRIVAL OF
RAIN...WITH A CHANGEOVER TO LIGHT SNOW LATE TONIGHT. MVFR CEILINGS
TO PERSIST THEN THROUGH THE END OF THE FORECAST PERIOD.

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SYNOPSIS...TDUD
NEAR TERM...CP
SHORT TERM...TDUD
LONG TERM....RYAN
AVIATION...RYAN/JP

AREA FORECAST DISCUSSION

NWS INDIANAPOLIS IN

246 PM EST MON FEB 18 2013

.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.

.SYNOPSIS...
ISSUED AT 350 AM EST MON FEB 18 2013

.NEAR TERM /REST OF TODAY/...

ISSUED AT 957 AM EST MON FEB 18 2013

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...

ISSUED AT 350 AM EST MON FEB 18 2013

.LONG TERM /THURSDAY THROUGH MONDAY/...

ISSUED AT 246 PM EST MON FEB 18 2013

MAIN FOCUS FOR THE EXTENDED REMAINS ON POTENTIAL FOR A WINTRY MIX
WITH STORM MOVING THROUGH THE REGION THURSDAY AFTERNOON AND
NIGHT WITH CHANCES FOR ADDITIONAL PRECIP RETURNING FOR EARLY NEXT WEEK.

.AVIATION /DISCUSSION FOR 181800Z TAF ISSUANCE/...

ISSUED AT 1229 PM EST MON FEB 18 2013

DETERIORATING FLYING CONDITIONS BY THIS EVENING WITH THE ARRIVAL OF
RAIN...WITH A CHANGEOVER TO LIGHT SNOW LATE TONIGHT. MVFR CEILINGS
TO PERSIST THEN THROUGH THE END OF THE FORECAST PERIOD.

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

SYNOPSIS...TDUD
NEAR TERM...CP
SHORT TERM...TDUD
LONG TERM....RYAN
AVIATION...RYAN

AREA FORECAST DISCUSSION

NWS INDIANAPOLIS IN

1229 PM EST MON FEB 18 2013

.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.

.SYNOPSIS...
ISSUED AT 350 AM EST MON FEB 18 2013

.NEAR TERM /REST OF TODAY/...

ISSUED AT 957 AM EST MON FEB 18 2013

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...

ISSUED AT 350 AM EST MON FEB 18 2013

.LONG TERM /THURSDAY THROUGH SUNDAY/...
ISSUED AT 255 AM EST MON FEB 18 2013

MAIN CHALLENGE TO THE EXTENDED CONTINUES TO BE TIMING OF
PRECIPITATION AND PRECIPITATION TYPE ASSOCIATED WITH A STRONG BUT
WEAKENING SYSTEM COMING OUT OF THE ROCKIES EARLY IN THE EXTENDED.

MODEL TO MODEL AND RUN TO RUN CONSISTENCY CONTINUE TO LACKING WITH
THE 00Z GFS AND 12Z ECMWF NOW A BIT FASTER WITH THE LOW CENTER THAN
THE 00Z GEM AND 21Z SREF. THE GFS AND ECMWF COMBO BRING THE
ASSOCIATED SURFACE LOW TO SOUTHWESTERN KANSAS BY 12Z THURSDAY WITH
THE OTHERS TRAILING A BIT ACROSS SOUTHWESTERN COLORADO.
MEANWHILE...THE 00Z GEFS SEEMED TO BE A GOOD COMPROMISE WITH THE LOW
ACROSS THE COLORADO AND KANSAS BORDER WITH THE LOW AT 12Z THURSDAY.
THIS IS ALSO WHERE A MAJORITY OF THE GEFS ENSEMBLES MEMBERS HAD THE
LOW. STILL...GEFS STANDARD DEVIATION FOR SURFACE PRESSURE WAS
MAXIMIZED IN THIS AREA. SO...PREFER TO GO WITH THE 00Z GEFS
REGARDING LOW POSITION AT THE START OF THE EXTENDED...BUT CONFIDENCE
IS NOT HIGH. THE 12Z ECMWF WAS THE ONLY MODEL TO BRING ANY QPF INTO
CENTRAL INDIANA FROM 12Z-18Z. LOOKING AT MODEL SOUNDINGS FROM
12Z-18Z...ALONG WITH CONDENSATION PRESSURE DEFICITS ON THE 295K
LEVEL...TOO MUCH DRY AIR IN THE MID AND LOWER LEVELS THROUGH 18Z FOR
MUCH IF ANY PRECIPITATION TO REACH THE GROUND...EVEN ACROSS THE
SOUTHWEST...WHERE WARM AIR ADVECTION WILL BE MAXIMIZED. FROM 18Z-00Z
THURSDAY...MODEL SOUNDINGS START TO MOISTEN IN THE MID AND LOWER
LEVELS AS STRONG WARM ADVECTION CONTINUES AND OVERRIDES COLD NEAR
SURFACE AIR. SOUNDINGS AND PARTIAL THICKNESS METHOD FROM
BUFKIT...SUGGESTS PRECIPITATION SHOULD START OFF AS SNOW AND THEN
SWITCH OR MIX WITH SLEET TOWARDS EVENING AND POSSIBLY RAIN OR SNOW.
THEN...MIX SHOULD BECOME MORE SLEET AND FREEZING RAIN THURSDAY
NIGHT...FREEZING RAIN OR RAIN SOUTH...AND EVENTUALLY ALL RAIN TOWARD
OR JUST AFTER 12Z FRIDAY AT WHICH POINT THE PRECIPITATION SHOULD BE
DISSIPATING AND MOVING OUT AS MOISTURE BECOMES MORE SHALLOW AND
OCCLUDED SYSTEM LIFTS NORTHEAST OF THE FORECAST AREA. SHOULD BE DRY
FROM LATE FRIDAY THROUGH SUNDAY AS HIGH PRESSURE BUILDS IN FROM THE
PLAINS.

GENERALLY ACCEPTED REGIONAL INITIALIZATION WITH BELOW NORMAL
TEMPERATURES ON THURSDAY AT MOSTLY ABOVE AFTER.

.AVIATION /DISCUSSION FOR 181800Z TAF ISSUANCE/...

ISSUED AT 1229 PM EST MON FEB 18 2013

DETERIORATING FLYING CONDITIONS BY THIS EVENING WITH THE ARRIVAL OF
RAIN...WITH A CHANGEOVER TO LIGHT SNOW LATE TONIGHT. MVFR CEILINGS
TO PERSIST THEN THROUGH THE END OF THE FORECAST PERIOD.

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

SYNOPSIS...TDUD
NEAR TERM...CP
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...RYAN

AREA FORECAST DISCUSSION

NWS GOODLAND KS

334 PM MST MON FEB 18 2013

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 302 PM MST MON FEB 18 2013

LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW ACTIVE PATTERN IN PLACE
ACROSS THE US WITH SEVERAL AMPLIFIED TROUGHS AND RIDGES. OVER THE
CENTRAL US A TROUGH CURRENTLY EXTENDS ACROSS THE NORTHERN PLAINS TO
NORTHERN TEXAS WITH A RIDGE UPSTREAM CENTERED OVER THE GREAT BASIN.
NW FLOW IS IN PLACE BETWEEN THESE FEATURES OVER OUR CWA...WITH
SUBSIDENCE CURRENTLY OVERHEAD AND A WEAK VORT MAX/EMBEDDED SHORTWAVE
TROUGH UPSTREAM OVER THE NEBRASKA PANHANDLE. AT THE SURFACE HIGH
PRESSURE IS BEGINNING TO BUILD OVER WESTERN KS WITH SURFACE GRADIENT
WEAKENING FROM THE WEST TO THE EAST...WHICH IS ALLOWING THE
STRONGEST WINDS TO DECREASE WELL BELOW ADVISORY CRITERIA.

THE WEAK TROUGH OVER THE NE PANHANDLE WILL QUICKLY PASS NORTH THIS
AFTERNOON AND EVENING WITH WEAK FORCING AND SOME MID LEVEL MOISTURE
MOVING ACROSS THE NORTHERN PART OF THE CWA. UPSTREAM RADARS ARE
SHOWING LIGHT REFLECTIVITIES...WHICH MATCH WHERE LATEST RUC PLACES
LIGHT QPF THROUGH THE AFTERNOON/EARLY EVENING HOURS. SURFACE TD
DEPRESSIONS ARE VERY LARGE...AND THIS LIKELY EXTENDS TO ABOUT 850MB
OR AROUND 8KFT BASED ON LATEST RUC SOUNDINGS. WITH LOW LEVELS THIS
DRY IT IS HARD FOR ME TO IMAGINE MUCH OF ANYTHING REACHING THE
SURFACE...THOUGH I COULDNT RULE OUT A FEW SPRINKLES OR FLURRIES
THROUGH ABOUT 1Z ACROSS THE NORTH.

H5 RIDGE WILL BUILD BACK OVER THE CWA TONIGHT AND TUESDAY WITH LARGE
SCALE SUBSIDENCE AND A VERY DRY AIRMASS EXPECTED TO BE IN PLACE.
THERE SHOULD BE SOME MODERATION OF THE AIR MASS IN PLACE BY TUESDAY
AFTERNOON WITH WAA AND GUSTY SOUTH WINDS DEVELOPING IN RESPONSE TO
LEE TROUGH DEEPENING OVER EASTERN COLORADO. I AM CURRENTLY EXPECTING
TEMPS IN NEAR 50F IN THE WEST TO MID 40S IN THE EAST...HOWEVER I
WOULDNT BE SURPRISED IF WE ARE A LITTLE WARMER THAN THIS.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 PM MST MON FEB 18 2013

WINTER STORM WATCH FROM WEDNESDAY THROUGH THURSDAY.

FORECAST FOCUS IS ON THE WINTER STORM EXPECTED TO IMPACT THE
FORECAST AREA ON WEDNESDAY AND THURSDAY.

CONFIDENCE IS HIGH IN THIS STORM OCCURRING OVER THE
REGION...ALTHOUGH DETAILS REMAIN TO BE SORTED OUT OVER THE NEXT
COUPLE OF DAYS AS THE STORM MOVES INTO THE WEST COAST AND BEGINS
TRACKING ACROSS THE FAR SOUTHWEST UNITED STATES. MAIN CONCERNS
WITH THIS STORM ARE THE EVENTUAL TRACK OF THE LOW CENTER AND THE
RESULTING AMOUNT OF COLD AIR IN PLACE OVER THE FORECAST AREA AND
EVENTUAL CHANGE-OVER TIME TO ALL SNOW. DEPENDING UPON THAT TRACK
AND TIMING...AREAS OF FREEZING PRECIPITATION AND RESULTING
SNOWFALL AMOUNTS COULD VARY GREATLY FROM WHAT IS CURRENTLY IN THE
FORECAST. HOWEVER...EVEN WITH THE POTENTIAL VARIATION IN THOSE
ELEMENTS...CONFIDENCE WAS HIGH ENOUGH IN THIS BEING A SIGNIFICANT
ENOUGH STORM TO WARRANT PUTTING OUT A WINTER STORM WATCH DUE TO
POSSIBLE AREAS OF FREEZING RAIN AND DRIZZLE COMBINED WITH MODERATE
TO HEAVY SNOW AND AREAS OF BLOWING SNOW.

FOLLOWING THIS EVENT...COLDER TEMPERATURES SHOULD REMAIN OVER THE
AREA WHERE HEAVIEST SNOWFALLS HAVE OCCURRED WITH TEMPERATURES
GRADUALLY WARMING THROUGH THE REMAINDER OF THE WEEK AND INTO THE
BEGINNING OF NEXT WEEK.

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1016 AM MST MON FEB 18 2013

VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD AT BOTH KGLD AND
KMCK. GUSTY WINDS WILL CONTINUE AT BOTH TERMINALS THROUGH THIS
AFTERNOON WITH GUSTS 35-40KT. BY LATE AFTERNOON SURFACE GRADIENT
BEGINS TO WEAKEN WHICH SHOULD ALLOW A GENERAL DECREASE IN WINDS
THROUGH SUNSET WHEN WINDS FINALLY DROP BELOW 12KT.

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY
AFTERNOON FOR KSZ001>004-013>016-027>029-041-042.

CO...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY
AFTERNOON FOR COZ090>092.

NE...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY
AFTERNOON FOR NEZ079>081.

SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...DR

AREA FORECAST DISCUSSION

NWS TOPEKA KS

320 PM CST MON FEB 18 2013

.DISCUSSION...
THE 20Z WATER VAPOR IMAGERY SHOWS THE UPPER TROUGH AXIS OVER
EASTERN KS MOVING EAST...WHILE ANOTHER UPPER LOW APPROACHED THE
PACIFIC NORTHWEST. AT THE SURFACE...A COLD FRONT HAS MOVES INTO
EASTERN OK AND WESTERN MO WITH COOLER AND DRIER AIR ADVECTING INTO
THE FORECAST AREA.

FOR TONIGHT...PRECIP SHOULD BE WELL OFF TO THE EAST WITH UPPER LEVEL
SUBSIDENCE INCREASING AS DRY AIR FILLS IN FROM THE NORTHWEST. MODELS
KEEP SOMEWHAT OF A PRESSURE GRADIENT OVER NORTHEAST KS AS SURFACE
RIDGING BUILD SOUTH THROUGH THE NORTHERN PLAINS. THIS SHOULD HELP
KEEP TEMPS FROM BOTTOMING OUT. ANOTHER CONCERN FOR OVERNIGHT LOWS IS
THE RAP PROG OF A STRATUS DECK REMAINING OVER NORTHEAST KS THROUGH
THE NIGHT. NONE OF THE OTHER MODELS SEEM TO AGREE WITH THIS AND
SATELLITE SHOWS A BROKEN STRATOCU FIELD ACROSS EASTERN NEB.
THEREFORE THINK THE RAP IS A BIT OVERDONE WITH THE CLOUDS...WHICH
ARE LIKELY A FUNCTION OF STEEP LOW LEVEL LAPSE RATES AND
INSTABILITY. ONCE THE BOUNDARY LAYER COOLS...THOSE LAPSE RATES
SHOULD RELAX AND THE STRATOCU FIELD DIMINISH. THINK LOWS WILL BE IN
THE UPPER TEENS TO LOWER 20S. SHORTWAVE RIDGING SHOULD DEVELOP FOR
TUESDAY WITH RIDGING AT THE SURFACE BUILDING IN. SO THE FORECAST IS
DRY WITH A COOL AND SUNNY DAY EXPECTED. COLD AIR ADVECTION FROM THE
NORTH SHOULD HOLD TEMPS IN THE 30S.

WOLTERS

CONFIDENCE IN A STRONG WINTER STORM IMPACTING THE AREA FOR THE MID
WEEK REMAINS ON TRACK. THE MODELS CONTINUE TO SHOW VERY LITTLE LARGE
SCALE VARIANCE...WITH THE MAIN NOTABLE ALTERATIONS BEING A SLIGHTLY
SLOWER TREND WITH THE UPPER TROF AND FARTHER SOUTH PLACEMENT OF THE
SURFACE LOW. THE SURFACE LOW IN FACT FILLS RATHER QUICKLY THURSDAY
AND STRONG ZONAL FLOW ALOFT DEVELOPS A SECONDARY LOW IN NORTHEAST
NEW MEXICO ON MANY RUNS. LARGE SCALE LIFT INCREASES FROM WEDNESDAY
AFTERNOON INTO THURSDAY MORNING VIA ISENTROPIC LIFT THEN Q-G
FORCING...WITH THE MAIN DRIVING FORCE FOR THE NEGATIVE TILT TO THE
UPPER TROF AXIS SEEN AS A DEEP POTENTIAL VORTICITY ANOMALY AROUND
50N AND 150W AT 18Z. PRECIPITABLE WATER VALUES DRAWN NORTH REMAIN
NEAR THE TWO STANDARD DEVIATION ABOVE NORMAL MARK WITH CONDITIONAL
SYMMETRIC TO UPRIGHT INSTABILITY IN THE UPPER LEVELS. THE DETAILS
REMAIN THE MAIN ISSUE AND WILL LIKELY CONTINUE TO BE THE MAIN
TROUBLE SPOT UNTIL THE EVENTS ONSET. THESE INCLUDE HOW COOL AND DRY
THE NEAR-SURFACE LAYER WILL BE...HOW FAST THE ISENTROPIC LIFT WILL
SATURATE THE COLUMN...HOW WARM AND FAR NORTH WILL THE WARM NOSE
AROUND 7000 FEET BE....AND HOW AND WHERE WILL LONG WILL ICE CRYSTALS
REMAIN IN THE CLOUD ALOFT. IN TERMS OF TEMPERATURES...THE SLIGHTLY
COOLER IDEA CONTINUES TO BE THE THEME...AND WITH THE FARTHER SOUTH
IDEA ALSO...DID TREND PRECIPITATION TYPES SOUTH A BIT. WIND SPEEDS
WILL BE CONSIDERABLE...BUT THE FILLING LOW SHOULD KEEP SPEEDS IN
CHECK A BIT...AND THE EXPECTED WET NATURE OF THE SNOW WOULD NOT
SUPPORT HIGH-END BLOWING AND DRIFTING. WITH SUCH PERSISTENT AND
CONSISTENT SOLUTIONS SEEN WITH THIS SYSTEM...EVEN AT THIS
RANGE...CONFIDENCE IS HIGH ENOUGH FOR MUCH OF THE AREA TO SEE
MODERATE TO HEAVY ACCUMULATIONS FOR A WATCH TO BE ISSUED AT THIS
RANGE.

MUCH MORE TRANQUIL CONDITIONS ARE EXPECTED FOR THE END OF THE
WEEK...WITH THE NEXT MORE SIGNIFICANT TROF COMING IN THE LATE PERIOD
OF THE FORECAST.

.AVIATION...
ASIDE FROM SOME BRIEF FLURRIES POSSIBLE...VFR CONDITIONS SHOULD
PREVAIL AS DRY AIR ADVECTS IN FROM THE NORTHWEST. THE LATEST RAP HAS
THROWN A CURVE BALL IN BRINGING MVFR CIGS IN FROM NEB OVERNIGHT.
THERE IS NO INDICATION OF THIS HAPPENING FROM ANY OTHER GUIDANCE
SOURCE. SO AT THIS POINT WILL KEEP A VFR FORECAST AND MONITOR TRENDS
UPSTREAM.

WOLTERS

.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR KSZ008>012-020>024-026-034>040-054>056-058-059.

AREA FORECAST DISCUSSION

NWS GOODLAND KS

144 PM MST MON FEB 18 2013

.SHORT TERM...(THIS AFTERNOON THROUGH TUESDAY)
ISSUED AT 143 PM MST MON FEB 18 2013

THE WEAK TROUGH OVER THE NE PANHANDLE WILL QUICKLY PASS NORTH THIS
AFTERNOON AND EVENING WITH WEAK FORCING AND SOME MID LEVEL MOISTURE
MOVING ACROSS THE NORTHERN PART OF THE CWA. UPSTREAM RADARS ARE
SHOWING LIGHT REFLECTIVITY...WHICH MATCH WHERE LATEST RUC PLACES
LIGHT QPF THROUGH THE AFTERNOON/EARLY EVENING HOURS. SURFACE TD
DEPRESSIONS ARE VERY LARGE...AND THIS LIKELY EXTENDS TO ABOUT 850MB
OR AROUND 8KFT BASED ON LATEST RUC SOUNDINGS. WITH LOW LEVELS THIS
DRY IT IS HARD FOR ME TO IMAGINE MUCH OF ANYTHING REACHING THE
SURFACE...THOUGH I COULDNT RULE OUT A FEW SPRINKLES OR FLURRIES
THROUGH ABOUT 1Z ACROSS THE NORTH.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 246 AM MST MON FEB 18 2013

TUESDAY NIGHT-WEDNESDAY...SHORT WAVE RIDGE WILL BE OVER THE AREA
INITIALLY BRINGING CONTINUED DRY CONDITIONS THROUGH TUESDAY EVENING.
AS THIS RIDGE SHIFTS TO THE EAST AS STRONG TROUGH MOVES INTO THE
FOUR CORNERS AREA...WINDS WILL BEGIN TO INCREASE SHARPLY DURING THE
OVERNIGHT HOURS AND REMAIN IN THE 25 TO 30 MPH RANGE AS CYCLOGENESIS
STRENGTHENS THROUGH THE PERIOD. WINDS WILL HOLD OVERNIGHT LOWS UP
SOMEWHAT...BUT WILL GRADUALLY ADVECT INCREASED MOISTURE INTO THE
AREA. SEEMS LIKE SFC TDS ARE SLOW TO RISE SO EXPECT A STRATUS DECK
TO BE A MORE LIKELY SCENARIO THAN FOG DEVELOPING DURING THE PERIOD.
DPRG/DT OF GFS/ECMWF SUPPORT PRECIPITATION DEVELOPMENT DURING THE
AFTERNOON HOURS IN ADVANCE OF STRONG PV ANOMALY. DATA SUGGESTING
THAT THERE WILL BE DRY MID LEVEL LAYER DURING THE LATE MORNING/EARLY
AFTERNOON HOURS WHICH COULD EFFECTIVELY ELIMINATE ANY ICE FROM
VERTICAL COLUMN. WITH A NEAR SATURATED LAYER NEAR THE SFC AND
INCREASED LARGE SCALE AND OROGRAPHIC LIFT...THINK THERE WILL BE A
THREAT FOR FREEZING DRIZZLE BEFORE PRECIPITATION INTENSITY INCREASES
LATE IN THE AFTERNOON WEDNESDAY.

WEDNESDAY NIGHT THROUGH SATURDAY...MAIN CONCERN WILL CONTINUE TO
BE THE STRONG WINTER STORM TO MOVE ACROSS THE PLAINS WEDNESDAY
THROUGH THURSDAY. OVERALL TREND HAS BEEN TO SHIFT IT SOUTH.

WEDNESDAY NIGHT THE SURFACE AND UPPER LEVEL CLOSED LOW BEGIN TO MOVE
INTO THE TRI-STATE AREA AS THE LEFT EXIT OF THE 500MB JET MOVES
ACROSS THE AREA. LIFT INCREASES THROUGH THE NIGHT AS THE SURFACE LOW
MOVES THROUGH THE SOUTHWEST PART OF THE AREA. WINDS WILL DECLINE
SOME AS AN INVERSION DEVELOPS NEAR THE SURFACE...BLOCKING THE LOW
LEVEL JET FROM REACHING THE GROUND. WIND GUSTS OF 30 MPH WILL BE
COMMON THROUGH THE NIGHT.

EARLY THURSDAY MORNING THE LEFT EXIT OF THE 500MB JET WILL MOVE OVER
THE EAST HALF OF THE AREA AHEAD OF THE CLOSED UPPER LEVEL LOW. ONCE
THE CLOSED LOW MOVES EAST OF THE AREA DURING THE AFTERNOON...LIFT WILL
QUICKLY DECLINE CAUSING THE SNOW TO END FROM SOUTHWEST TO
NORTHEAST. AT THE SURFACE THE LOW WILL CLOSELY FOLLOW THE UPPER
LEVEL FEATURE. BEHIND THE SURFACE LOW A STRONG COLD FRONT WILL
MOVE INTO THE AREA. THE COLDER AIR BEHIND THE FRONT WILL ALLOW
STRONGER WINDS BEHIND THE SURFACE LOW TO REACH THE
GROUND...INCREASING THE BLOWING SNOW THREAT DURING THE LATE
MORNING AND AFTERNOON.

LATE WEDNESDAY NIGHT THROUGH EARLY THURSDAY MORNING WHEN LIFT IS THE
STRONGEST...THERE MAY BE A PERIOD OF SNOWFALL RATES IN EXCESS OF AN
INCH AN HOUR. SNOWFALL TOTALS WILL BE HIGHEST FROM MCCOOK TO HILL
CITY WHERE LIFT FROM THE STORM SYSTEM WILL LINGER THE LONGEST...WITH
AMOUNTS DECLINING TO THE SOUTHWEST.

THE NEXT CHANCE FOR PRECIPITATION WILL BE SUNDAY AS AN UPPER LEVEL
TROUGH MOVES INTO THE AREA FROM THE NORTHWEST.

TEMPERATURES FOR THE PERIOD WILL BE BELOW NORMAL AS THE WINTER STORM
MOVES IN...THEN GRADUALLY WARMING TO NEAR NORMAL AHEAD OF THE NEXT
UPPER LEVEL TROUGH WHEN TEMPERATURES RETURN TO BELOW NORMAL.

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1016 AM MST MON FEB 18 2013

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

SHORT TERM...DR
LONG TERM...JRM/JTL
AVIATION...DR

AREA FORECAST DISCUSSION

NWS TOPEKA KS

1130 AM CST MON FEB 18 2013

.DISCUSSION...
MADE SOME CALLS TO LOCATIONS UNDER THE HIGH REFLECTIVITY BAND IN
NORTHERN KS AND MOST REPORTS ARE OF JUST SOME FLURRIES. THEREFORE
THINK THAT PRECIP WILL FOR THE MOST PART REMAIN A TRACE EVENT THIS
AFTERNOON. FRONTOGENESIS SHOULD MOVE EAST BY THE LATE AFTERNOON
TAKING THE BAND OF PRECIP WITH IT.

WOLTERS

.PREV DISCUSSION... /445 AM CST MON FEB 18 2013/
TODAY THROUGH TUESDAY NIGHT...WATER VAPOR SATELLITE IMAGERY SHOWING
SHORTWAVE TROUGH EXTENDING FROM THE NORTHERN PLAINS SOUTHWESTWARD
INTO THE CENTRAL HIGH PLAINS MOVING STEADILY EASTWARD. A COLD FRONT
IS ALSO MAKING SOUTHEASTWARD PROGRESS ACROSS SOUTHEAST NE AND
NORTHERN KS. STRONG SOUTH WINDS GUSTING TO 30 TO 40 MPH WILL BECOME
NORTHWEST FOLLOWING THE FRONTAL PASSAGE THIS MORNING...THEN SLOWLY
DECREASE IN THE AFTERNOON. FOR NOW EXPECT WIND SPEEDS TO STAY JUST
BELOW WIND ADVISORY CRITERIA. AS STRATUS FORMS/SURGES NORTHWARD
THIS MORNING THERE MAY BE SOME DRIZZLE SOUTH AND EAST OF I 35.
ALSO...AS THE SHORTWAVE OVER THE CENTRAL HIGH PLAINS MOVES EASTWARD
THERE MAY ALSO BE ENOUGH POST FRONTAL AND MID LEVEL FORCING FOR A
FEW SPRINKLES OF SNOW FLURRIES FROM MID MORNING INTO THE EARLY
AFTERNOON HOURS...OTHERWISE EXPECT THE FCST TO BE DRY TODAY...WITH
CLEARING SKIES BY EVENING. MILD MID FEB. TEMPS EARLY THIS MORNING IN
THE 40S AND 50S...WILL GRADUALLY FALL THROUGH THE LATE MORNING AND
AFTERNOON. WILL THEN MAINTAIN A DRY FCST THROUGH TONIGHT...TUESDAY
AND TUESDAY NIGHT WITH MOSTLY CLEAR SKIES.

WEDNESDAY THROUGH FRIDAY...MODELS ARE IN AGREEMENT IN BRINGING A
STRONG STORM SYSTEM OUT OF THE DESERT SOUTHWEST AND INTO THE CENTRAL
HIGH PLAINS WEDNESDAY NIGHT AND ACROSS THE CWA ON THURSDAY.
HOWEVER...OVERALL TREND OF THE MODELS HAS BEEN A SLIGHTLY FURTHER
SOUTH TRACK OF THE UPPER SYSTEM AND SFC LOW. THIS HAS LED TO A
HIGHER CONFIDENCE LEVEL THAT THE COLDER...DRIER AIR FILTERING IN
BEHIND THE CURRENT SYSTEM MAY REMAIN IN PLACE/PERSIST LONGER INTO
WEDNESDAY/WEDNESDAY NIGHT THAN EXPECTED. THIS WOULD LIKELY
CONTRIBUTE TO MORE EVAPORATIVE COOLING AND MAINTAINING OF COLD AIR
IN THE LOW AND MID LEVELS WEDNESDAY AFTERNOON AND NIGHT...AND A
HIGHER LIKELIHOOD OF ACCUMULATING SNOW. WITH THE MORE SOUTHERLY
TRACK THE DRY SLOT MAY BE A LITTLE FURTHER SOUTH AND EAST WHICH
WOULD KEEP THE NORTHWEST PORTIONS OF THE CWA IN THE SNOW LONGER
BEFORE DECREASING THURSDAY AFTERNOON AS DRIER AIR/LOSS OF ICE IN THE
MID LEVELS OCCURS. STILL EXPECT PRECIP TYPE ACROSS THE NORTH 1/3 OF
THE CWA TO REMAIN PRIMARILY SNOW THROUGH THE EVENT...BUT MIXING
WITH/CHANGING TO A SNOW/SLEET POTENTIAL IN THE I 70 CORRIDOR...WITH
SNOW/SLEET/FREEZING RAIN MIXTURE ACROSS THE SOUTH TO MOSTLY RAIN
WITH THE WARMER TEMPS/DRY SLOT THURSDAY AFTERNOON. AS THE DRY SLOT
SHIFTS EASTWARD THURSDAY NIGHT...SOME POTENTIAL FOR WRAP AROUND
LIGHT SNOW/FREEZING DRIZZLE...PRIMARILY BEFORE MIDNIGHT.
OVERALL...EXPECT HIGHER SNOW AND SLEET ACCUMULATIONS THIS
FCST...RANGING FROM AN INCH OR TWO ACROSS THE SOUTH (MAINLY
WEDNESDAY NIGHT/EARLY THURSDAY)...TO POTENTIALLY OVER 6 INCHES OF
SNOW ACROSS THE NORTHERN CWA. THIS OF COURSE COULD CHANGE WITH ANY
FURTHER ADJUSTMENTS IN THE FCST TRACK OF THE SYSTEM OVER THE NEXT
COUPLE OF DAYS.

THERE SHOULD BE BREAK IN PRECIP CHANCES FOR THE DAYTIME FRIDAY
THROUGH SATURDAY BEFORE ANOTHER STORM SYSTEM APPROACHES THE AREA
SUNDAY AND SUNDAY NIGHT WITH ANOTHER CHANCE FOR A WINTRY MIX.

.TOP WATCHES/WARNINGS/ADVISORIES...NONE.

AREA FORECAST DISCUSSION

NWS GOODLAND KS

1015 PM MST SUN FEB 17 2013

.UPDATE...
ISSUED AT 915 PM MST SUN FEB 17 2013

HAVE DEBATED BACK AND FORTH THE PAST FEW HOURS WHETHER OR NOT TO
KEEP THE WIND ADVISORY GOING OR CANCEL IT. GIVEN THE BORDERLINE
NATURE OF POTENTIAL GUSTS TO 45 MPH AND THE ISOLATED NATURE THAT
THESE GUSTS COULD OCCUR FELT THE BEST COURSE OF ACTION WAS TO
CANCEL IT.

AT 0420Z COLD FRONT HAD PUSHED THROUGH THE NORTHWEST 1/3 OR SO OF
THE AREA WITH NORTHWEST WINDS GUSTING 30 TO 40 MPH. THIS MATCHES
WELL WITH 3 HOUR PRESSURE RISES OF 4-8MB. THIS AXIS OF STRONGER
PRESSURE RISES WILL SLOWLY SPREAD EAST/SOUTHEAST BEHIND THE FRONT
THROUGH THE REMAINDER OF THE NIGHT INTO EARLY MONDAY MORNING. FELT
20 TO 30 MPH WINDS WITH GUSTS OF 40 MPH WAS BETTER SUITED TO THE
SITUATION VS AN ADVISORY.

OTHER ADJUSTMENTS WERE TO FINE TUNE THE TEMPS/DEWPOINTS BOTH AHEAD
OF AND BEHIND THE FRONT AND BEEF UP CLOUD COVER TONIGHT.

UPDATE ISSUED AT 508 PM MST SUN FEB 17 2013

HAVE CANCELLED THE RED FLAG WARNING AS WINDS HAVE REMAINED WELL
BELOW THRESHOLDS.

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 229 PM MST SUN FEB 17 2013

LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW SHORTWAVE RIDGE OVER
THE CWA...WITH SHORTWAVE TROUGH ACROSS THE NORTHERN ROCKIES
EXTENDING SOUTH OVER THE GREAT BASIN. AT THE SURFACE A STRONG COLD
FRONT EXTENDS FROM NORTH DAKOTA ACROSS EASTERN WYOMING AND SOUTH
ACROSS EASTERN UTAH. STRONG SUBSIDENCE IS ALREADY APPARENT ON WV
IMAGERY BEHIND THIS FRONT.

CLOUD COVER HAS REMAINED IN PLACE OVER THE CWA...WHICH HAS
RESTRICTED MIXING RESULTING IN WEAKER WINDS THAN ORIGINALLY
EXPECTED. RH VALUES HAVE DROPPED WELL BELOW RFW CRITERIA ACROSS THE
REGION...WITH SINGLE DIGIT RH VALUES AT MANY LOCATIONS. ONLY A FEW
LOCATIONS SO FAR HAVE REACHED WIND CRITERIA FOR WIND...WITH MANY
OTHER LOCATIONS BORDERLINE. I PLAN ON LEAVING THE RFW IN PLACE FOR
NOW...DUE TO HOW DRY WE ARE...AND THE POTENTIAL FOR WINDS TO
INCREASE BETWEEN NOW AND 00Z.

A STRONG COLD FRONT OVER THE NORTHERN PLAINS WILL DROP SOUTH OVER
THE CWA THIS EVENING AND OVERNIGHT. GFS/NAM BOTH INDICATE 40-50KT
WINDS BEHIND THIS FRONT OVER OUR CWA...WITH BL WINDS 20-30KT. STRONG
PRESSURE GRADIENT COMBINED WITH STRONG SUBSIDENCE SHOULD HELP BRING
WINDS TO THE SURFACE. WHILE THESE CONDITIONS MAY ONLY LAST AN HOUR
OR TWO AT THE MOST...I WAS CONFIDENT ENOUGH TO ISSUE WIND ADVISORY
FOR THE SUDDEN ONSET OF GUSTS TO 55 MPH AND THE POSSIBILITY OF
BLOWING DUST STARTING AT 03Z. ORIGINALLY I CONSIDERING EXTENDING
THIS ADVISORY THROUGH THE DAY TOMORROW. HOWEVER...PRESSURE GRADIENT
SHOULD BEGIN TO RELAX AS FRONT MOVES SOUTH AND EAST...AND DAYTIME
MIXING IS STILL IN QUESTION IF CLOUDS LINGER THROUGH THE DAY. I
HAVE CURRENT ADVISORY ENDING AT 12Z TO ALLOW NEXT SHIFTS TO
REEVALUATE FOR TOMORROW.

STRONG FORCING AND DECENT MID LEVEL MOISTURE WILL BE IN PLACE
OVERNIGHT WITH SHORTWAVE TROUGH PASSAGE...HOWEVER LOWER LEVELS
REMAIN VERY DRY. GFS/ECMWF ARE SHOWING LIGHT QPF IN THE WEST...WITH
GEM CREATING A BULLSEYE IN THE NORTHEAST. WHILE I COULDNT RULE OUT A
FEW FLURRIES OR SPRINKLES...I WAS NOT CONFIDENT ENOUGH THAT ANYTHING
WOULD REACH THE GROUND...SO I LEFT MENTION OUT.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 229 PM MST SUN FEB 17 2013

LONG TERM FOCUS REMAINS ON THE UPPER 4-CORNERS LOW EMERGING EAST
OF THE ROCKIES OVER THE HIGH PLAINS IN THE VICINITY OF NORTHEAST
NEW MEXICO/SOUTHEAST COLORADO/SOUTHWEST KANSAS EARLY THURSDAY
MORNING. MODELS HAVE REMAINED CONSISTENT WITH EACH OTHER AND HAVE
ONLY VARIED SLIGHTLY WITH LOW CENTER PLACEMENT FROM RUN TO RUN.
AM THEREFORE CONFIDENT WITH WIDESPREAD PRECIPITATION SHOWN ACROSS
THE ENTIRE FORECAST AREA AND AM CONFIDENT IN STAYING WITH THE
HIGHER POPS FOR THIS EVENT. TEMPERATURES ARE SOMEWHAT MORE
QUESTIONABLE AS THERE HAS BEEN SOME VARIATION IN TIMING AND EXTENT
OF THE COLD AIR MOVING INTO THE REGION ALONG WITH THE EVENTUAL
CHANGE OVER TO SNOW AND THE POSSIBILITY OF SOME INSTABILITY AND
THUNDER AS THIS EVENT INITIATES.

CONDITIONS WILL REMAIN DRY WITH HIGH TEMPERATURES ON TUESDAY
REMAINING SIMILAR TO MONDAY. OVERNIGHT LOWS WILL BE WARMER
TUESDAY NIGHT/EARLY WEDNESDAY AS CLOUDS BEGIN TO SPREAD EAST OF
THE ROCKIES AHEAD OF THE LOW PRESSURE SYSTEM AS IT MOVES INTO THE
INTERMOUNTAIN REGION. COOLER HIGH PRESSURE AT THE SURFACE WILL
CONTINUE TO SLIDE SOUTH INTO THE PLAINS STATES AND BACK INTO THE
FORECAST AREA FROM THE EAST WITH RETURN FLOW AROUND THE HIGH
BRINGING MORE MOISTURE INTO THE REGION. IT APPEARS A DRYLINE/WARM
FRONT FEATURE MOVES ACROSS THE CENTRAL HIGH PLAINS BY LATE
WEDNESDAY...BRINGING THE POTENTIAL FOR ISOLATED THUNDERSTORMS
ALONG WITH RAIN SHOWERS FOR THE WARMER AREAS WHILE SNOW IS
POSSIBLE MAINLY ACROSS THE NORTHEAST LATE. WEDNESDAY NIGHT/EARLY
THURSDAY THE LOW CENTER MOVES INTO SOUTHWEST KANSAS...WRAPPING
COLDER AIR AND MOISTURE AROUND THE SYSTEM WITH POSSIBLE HEAVY SNOW
ACROSS THE NORTHEAST PORTION OF THE FORECAST AREA DURING THAT
TIME. PRECIPITATION IS EXPECTED TO TAPER OFF DURING THE DAY ON
THURSDAY AND END BY THURSDAY EVENING. WINDS MAY BE GUSTY WITH THE
SYSTEM AND PRODUCE AREA OF BLOWING SNOW.

COLDEST TEMPERATURES OF THE WEEK WILL BE ON THURSDAY AND THURSDAY
NIGHT AS THE SYSTEM MOVES OUT WITH FRESH SNOW AND A POSSIBLE
DECREASE IN SKY COVER OVERNIGHT. CONDITIONS FRIDAY AND SATURDAY
WILL BE DRY WITH TEMPERATURES WARMING GRADUALLY WITH A BRIEF SHORT
WAVE RIDGE ALOFT ON SATURDAY AHEAD OF THE NEXT TROUGH SWINGING
THROUGH THE UPPER FLOW AND ACROSS THE ROCKIES LATE SUNDAY.

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1015 PM MST SUN FEB 17 2013

VFR CONDITIONS EXPECTED THROUGH THE PERIOD AT KGLD AND KMCK.
NORTHWEST WINDS 25G35KTS WILL BE COMMON THROUGH MUCH OF THE PERIOD
BEFORE DECREASING AROUND 00Z THEN QUICKLY FALLING INTO THE 5-10KT
RANGE BY 01-02Z. CLOUDINESS WILL INITIALLY REMAIN LIMITED TO
CIRRUS LEVEL BUT WILL LOWER BEHIND THE FRONT AND CONTINUE THROUGH
THE DAY MONDAY. HOWEVER...AT THIS TIME THE LOWER CLOUD HEIGHTS
WILL NOT IMPACT FLIGHT CATEGORIES SO WILL NOT DETAIL IN TAF FOR
EITHER SITE.

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

UPDATE...99
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...99

AREA FORECAST DISCUSSION

NWS GOODLAND KS

921 PM MST SUN FEB 17 2013

.UPDATE...
ISSUED AT 915 PM MST SUN FEB 17 2013

OTHER ADJUSTMENTS WERE TO FINE TUNE THE TEMPS/DEWPOINTS BOTH AHEAD
OF AND BEHIND THE FRONT AND BEEF UP CLOUD COVER TONIGHT.

UPDATE ISSUED AT 508 PM MST SUN FEB 17 2013

HAVE CANCELLED THE RED FLAG WARNING AS WINDS HAVE REMAINED WELL
BELOW THRESHOLDS.

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 229 PM MST SUN FEB 17 2013

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 229 PM MST SUN FEB 17 2013

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 400 PM MST SUN FEB 17 2013

VFR CONDITIONS EXPECTED THROUGH THE PERIOD AT KGLD AND KMCK.
SOUTH TO SOUTHWEST WINDS AROUND 10KTS AT TAF ISSUANCE WILL SHIFT
TO THE NORTHWEST AT 25KTS WITH GUSTS TO 35KTS OR SO BETWEEN 03Z-
04Z AT BOTH TERMINALS AS A COLD FRONT MOVES THROUGH. THESE WINDS
WILL REMAIN IN THE 25G35KT RANGE THROUGH MUCH OF THE PERIOD WITH A
SLIGHT DECREASE AROUND 23Z MONDAY. CLOUDINESS WILL INITIALLY REMAIN
LIMITED TO CIRRUS LEVEL BUT WILL LOWER BEHIND THE FRONT.
HOWEVER...AT THIS TIME THE LOWER CLOUD HEIGHTS WILL NOT IMPACT
FLIGHT CATEGORIES SO WILL NOT DETAIL IN TAF FOR EITHER SITE.

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

UPDATE...99
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...99

AREA FORECAST DISCUSSION

NWS PITTSBURGH PA

553 PM EST MON FEB 18 2013

.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA EARLY ON TUESDAY...BRINGING A
WINTRY MIX TO THE AREA. BEHIND THE FRONT...SNOW SHOWERS CAN BE
EXPECTED ACROSS THE AREA AS AN ARCTIC AIR MASS SETTLES INTO THE
REGION TUESDAY NIGHT INTO WEDNESDAY. HIGH PRESSURE WILL RETURN DRY
WEATHER ON THURSDAY BEFORE THE NEXT FRONTAL SYSTEM BRINGS A WINTRY
MIX TO THE AREA ON FRIDAY.

.NEAR TERM /THROUGH TUESDAY/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A 500MB RIDGE AXIS
CENTERED OVER THE OHIO VALLEY. DRY AIR IN THE 1000-500MB LAYER IS
ADVECTING INTO THE AREA WITH THIS FEATURE WITH 450-250MB MOISTURE
ASSOCIATED WITH CIRRUS SPILLING OVER THE RIDGE AND INTO THE AREA.
AT THE SURFACE...A SURFACE LOW IS CENTERED ACROSS THE UPPER
MIDWEST WITH A COLD FRONT EXTENDING SOUTHWARD ACROSS THE
MISSOURI VALLEY AND INTO THE SOUTHERN PLAINS. A WARM FRONT EXTENDS
FROM A WEAKER LOW ALONG THE FRONT IN IOWA EASTWARD INTO THE OHIO
VALLEY.

TONIGHT...SREF/WRF-ARW/WRF-NMM ARE IN AGREEMENT THAT MID-LEVEL
RIDGING WILL SHIFT EAST OF THE AREA TONIGHT WITH THE FRONT EDGE OF
PRECIPITATION AHEAD OF A COLD FRONT REACHING EASTERN OHIO BY AROUND
06Z. PRECIPITATION WILL HAVE TO OVERCOME AN INITIAL DRY LAYER...AND
BELIEVE THAT DYNAMIC COOLING/WET BULBING WITH THE SATURATION OF THIS
LAYER WILL ALLOW FOR SNOW AT THE ONSET OF THE EVENT FOR MOST
LOCATIONS EAST OF OHIO. 1000-500MB AND 1000-850MB CRITICAL THICKNESS
LINES WILL BE NORTH OF THE AREA TO BEGIN THE EVENT...HOWEVER WITH
THE FRONT MOVING INTO THE AREA...5400M/1300M LINES RESPECTIVELY
BOTH QUICKLY DROP SOUTHEAST OF THE AREA WITH THE FRONT. IN
ADDITION...WET BULB ZERO LINE STRADDLES THE FORECAST AREA AT THE
ONSET OF PRECIP. THUS...INITIAL SLEET/SNOW WITH WET BULBING IS
EXPECTED WITH A CHANGE OVER TO RAIN BY 12Z FOR MOST OF THE
LOWLANDS. FOR LOCATIONS NORTHEAST OF A FRANKLIN-INDIANA LINE AND
THE LAUREL HIGHLANDS/ALLEGHENY FRONT...COLD AIR WILL BE DAMMED
INTO THE AREA AND ALLOW FOR SOME FZRA/SLEET TO OCCUR AFTER THE
INITIAL SHOT OF SNOW AT THE ONSET.

QPF IN THE 06Z-12Z WINDOW WILL RANGE FROM THREE TENTHS IN EASTERN
OHIO TO AROUND A FEW HUNDREDTHS FOR THE EASTERN RIDGES. THUS...HAVE
A HALF INCH TO AN INCH OF SNOWFALL ACROSS INITIALLY NORTH OF
PITTSBURGH AND A FEW HUNDREDTHS OF ICE FOR THE AFOREMENTIONED
EASTERN RIDGES AND LOCATIONS NORTHEAST OF PITTSBURGH THAT COULD
HAVE SOME FZRA.

MAV/MET/SREF INDICATE THAT TEMPS WILL ONLY DROP OFF SLIGHTLY TONIGHT
WITH LOWS RANGING FROM THE LOWER 30S NORTHEAST OF PITTSBURGH AND
ACROSS THE EASTERN RIDGES TO THE UPPER 30S IN PORTIONS OF EASTERN
OHIO.

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
NAM/GFS/ECMWF ARE IN REASONABLE AGREEMENT THAT AN UPPER LEVEL LOW
WILL MOVE ACROSS THE GREAT LAKES REGION ON TUESDAY...PUSHING THE
FRONT FROM EASTERN OHIO INTO WESTERN PA IN THE 12Z-18Z WINDOW WITH
THE FRONT SHIFTING EAST OF THE AREA IN THE 18Z-21Z WINDOW. MODELS
ARE IN REASONABLE AGREEMENT WITH ONE TO TWO TENTHS OF QPF. THE
MORE DIFFICULT FORECAST WILL BE PRECIP TYPE. A MODEL CONSENSUS HAS
THE 850MB 0C LINE WILL EXTENDING FROM FRANKLIN TO PITTSBURGH TO
MORGANTOWN AT 12Z TUESDAY WITH CAA QUICKLY BRINGING TEMPS TO -4C
TO -10C ACROSS THE AREA BY 18Z. THUS...BELIEVE PRECIP WILL BE ALL
SNOW BY 18Z ACROSS THE AREA. HOWEVER...GFS/NAM TIME-HEIGHT CROSS-
SECTIONS ARE INDICATING THAT A 750-500MB DRY SLOT WILL BE CO-
LOCATED WITH THE DENDRITIC GROWTH ZONE FROM 15Z-21Z...MAKING
SPRINKLES OR DRIZZLE MORE LIKELY IN THAT PERIOD AND LIMITING
SNOWFALL. STILL...THE BIGGEST QUESTION IS...WITH THE FRONTAL
PASSAGE DURING THE DAY...HOW MUCH OF THE QPF WILL BE SNOW AND HOW
MUCH OF IT WILL ACCUMULATE BEFORE THE DRY SLOT ADVECTS INTO THE
AREA BEHIND THE FRONT. GIVEN THE DIURNALLY UNFAVORABLE PASSAGE
TIME...HAVE GONE WITH AN INCH OR LESS OF SNOW FOR LOCATIONS SOUTH
OF PITTSBURGH WITH 1 TO 3 INCHES NORTH AND EAST OF PITTSBURGH.

WITH THE COMBINATION OF A WINTRY MIX AT THE ONSET AND LIGHT SNOW/SLEET
ACCUMULATION...HAVE GONE WITH A WINTER WEATHER ADVISORY FOR
FOREST/JEFFERSON/INDIANA AND THE EASTERN RIDGES BEGINNING AT 08Z
TUESDAY AND CONTINUING UNTIL 16Z WHEN SURFACE TEMPS WARM ABOVE
FREEZING...HENCE BRINGING AN END TO FZRA. IF TDS DO NOT RESPONSE
FURTHER AND REMAIN IN THE TEENS/LOW 20S AT THE ONSET OF
PRECIP...ADVISORY WILL NEED TO BE EXPANDED FURTHER WESTWARD IN PA.

THE UPPER LOW WILL PUSH INTO THE NORTHEAST TUESDAY NIGHT INTO
WEDNESDAY WITH A BROAD CYCLONIC FLOW ACROSS THE UPPER OHIO VALLEY
THROUGH THIS PERIOD. BEHIND THE COLD FRONT...THE LOW-LEVEL FLOW WILL
VEER FROM SOUTHWESTERLY TO WESTERLY AT 06Z AND CLOSER TO
WEST-NORTHWESTERLY BY 12Z WED. WITH A PARTIALLY FROZEN LAKE
ERIE...THIS SCENARIO FAVORS MOVE OF A WEAK UPSLOPING EVENT FOR THE
RIDGES WITH BOTH LAKE MICHIGAN AND HURON AS POTENTIAL MOISTURE
SOURCES WITH A VORT ENERGY PROVIDING FORCING TUESDAY NIGHT.
THUS...BELIEVE AN ADDITIONAL 1 TO 3 INCHES WILL BE POSSIBLE TUESDAY
NIGHT INTO WEDNESDAY. FOR THE LOWLANDS...SCATTERED SNOW SHOWERS WILL
LEAD TO A GENERAL INCH ACROSS THE AREA THROUGH THIS PERIOD.

WEDNESDAY NIGHT THROUGH THURSDAY...THE UPPER LOW WILL PUSH WELL EAST
OF THE AREA WITH WEAK RIDGING AND A SURFACE HIGH RETURNING TO THE
AREA. THIS WILL BRING AN END TO ANY LINGERING LAKE EFFECT/UPSLOPING
SNOW SHOWERS ON WEDNESDAY NIGHT WITH A DRY FORECAST ON THURSDAY.

TEMPS WILL BE AROUND 15 DEGREES BELOW NORMAL IN THE WAKE OF THE
FRONT TUES NIGHT THRU WED NIGHT. TEMPS WILL BEGIN TO MODERATE ON
THURSDAY WITH HIGHS 5 TO 10 DEGREES BELOWN NORMAL AS THE CORE OF
COLDEST AIR ADVECTS EAST OF THE AREA.

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A DEEP TROUGH ACROSS THE WESTERN CONUS WILL CLOSE OFF INTO A LOW
ACROSS THE NORTHERN PLAINS THURSDAY NIGHT WITH AN OCCLUDING/OCCLUDED
FRONTAL BOUNDARY APPROACHING THE UPPER OHIO VALLEY. THIS FRONT WILL
CROSS THE REGION LATER THURSDAY NIGHT AND FRIDAY. LIKELY POPS AS
THIS SYSTEM PASSES WITH SNOW TO A WINTRY MIX THEN RAIN AS THE FRONT
PROGRESSES EASTWARD. REGION WILL THEN BE IN WEAK COLD ADVECTION
FRIDAY NIGHT INTO SATURDAY. SCATTERED RAIN AND SNOW SHOWERS POSSIBLE
INTO LATE SATURDAY. A GREAT DEAL OF UNCERTAINTY FOR THE WEEKEND AS
MODELS HAVE TIMING AND STRENGTH DIFFERENCES WITH A POSSIBLE COASTAL
LOW DEVELOPING SATURDAY. HIGH PRESSURE WILL THEN RETURN FOR DRY AND
SEASONABLE CONDITIONS FOR SUNDAY. LEFT MONDAY DRY FOR NOW BUT THE
NEXT FAST MOVING STORM SYSTEM WILL BE APPROACHING THE LOWER OHIO
VALLEY AND THIS FORECAST WILL LIKELY CHANGE GREATLY WITH TIME.

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS WILL PERSIST FOR THE FIRST HALF OF THE NIGHT BEFORE
A FRONTAL BOUNDARY APPROACHES THE REGION. LOW LEVEL WIND SHEAR
INCLUDED AT ALL TERMINALS LATER THIS EVENING INTO TOMORROW AS LOW
LEVEL JET SURGES FROM THE SOUTHWEST.

PRECIPITATION WILL START OFF AS A RAIN SNOW MIX AT TERMINALS ALONG
PIT AND NORTH AND EVENTUALLY CHANGE OVER TO SNOW ONCE COLDER AIR
USHERS IN WITH COLD FRONT.

IFR CEILINGS WILL OCCUR WITH SNOW AND BEHIND THE FRONTAL PASSAGE
WITH WINDS TURNING SOUTHWEST AND GUSTING TO OVER 20KT LATER
AFTERNOON TUESDAY.

.OUTLOOK.../TUESDAY THROUGH SATURDAY/...
LINGERING RESTRICTIONS ARE ANTICIPATED THROUGH WEDNESDAY IN COLD
NORTHWEST FLOW BEHIND THE FRONT. VFR UNDER HIGH PRESSURE THURSDAY.
POSSIBLE RESTRICTIONS FRIDAY AND SATURDAY IN AN UNSETTLED WEATHER
PATTERN.

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY FROM 3 AM TO 11 AM EST TUESDAY FOR
MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY FROM 3 AM TO 11 AM EST TUESDAY FOR
PAZ009-016-023-074-076.
WV...WINTER WEATHER ADVISORY FROM 3 AM TO 11 AM EST TUESDAY FOR
WVZ023-041.

AREA FORECAST DISCUSSION

NWS PITTSBURGH PA

311 PM EST MON FEB 18 2013

.NEAR TERM /THROUGH TONIGHT/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A 500MB RIDGE AXIS
CENTERED OVER THE OHIO VALLEY. DRY AIR IN THE 1000-500MB LAYER IS
ADVECTING INTO THE AREA WITH THIS FEATURE WITH 450-250MB MOISTURE
ASSOCIATED WITH CIRRUS SPILLING OVER THE RIDGE AND INTO THE AREA.
AT THE SURFACE...A SURFACE LOW IS CENTERED ACROSS THE UPPER
MIDWEST WITH A COLD FRONT EXTENDING SOUTHWARD ACROSS THE
MISSOURI VALLEY AND INTO THE SOUTHERN PLAINS. A WARM FRONT EXTENDS
FROM A WEAKER LOW ALONG THE FRONT IN IOWA EASTWARD INTO THE OHIO
VALLEY.

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
NAM/GFS/ECMWF ARE IN REASONABLE AGREEMENT THAT AN UPPER LEVEL LOW
WILL MOVE ACROSS THE GREAT LAKES REGION ON TUESDAY...PUSHING THE
FRONT FROM EASTERN OHIO INTO WESTERN PA IN THE 12Z-18Z WINDOW WITH
THE FRONT SHIFTING EAST OF THE AREA IN THE 18Z-21Z WINDOW. MODELS
ARE IN REASONABLE AGREEMENT WITH ONE TO TWO TENTHS OF QPF. THE
MORE DIFFICULT FORECAST WILL BE PRECIP TYPE. A MODEL CONSENSUS HAS
THE 850MB 0C LINE WILL EXTENDING FROM FRANKLIN TO PITTSBURGH TO
MORGANTOWN AT 12Z TUESDAY WITH CAA QUICKLY BRINGING TEMPS TO -4C
TO -10C ACROSS THE AREA BY 18Z. THUS...BELIEVE PRECIP WILL BE ALL
SNOW BY 18Z ACROSS THE AREA. HOWEVER...GFS/NAM TIME-HEIGHT CROSS-
SECTIONS ARE INDICATING THAT A 750-500MB DRY SLOT WILL BE CO-
LOCATED WITH THE DENDRITIC GROWTH ZONE FROM 15Z-21Z...MAKING
SPRINKLES OR DRIZZLE MORE LIKELY IN THAT PERIOD AND LIMITING
SNOWFALL. STILL...THE BIGGEST QUESTION IS...WITH THE FRONTAL
PASSAGE DURING THE DAY...HOW MUCH OF THE QPF WILL BE SNOW AND HOW
MUCH OF IT WILL ACCUMULATE BEFORE THE DRY SLOT ADVECTS INTO THE
AREA BEHIND THE FRONT. GIVEN THE DIURNALLY UNFAVORABLE PASSAGE
TIME...HAVE GONE WITH AN INCH OR LESS OF SNOW FOR LOCATIONS SOUTH
OF PITTSBURGH WITH 1 TO 3 INCHES NORTH AND EAST OF PITTSBURGH.

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
VFR CONDITIONS INTO FIRST HALF OF TONIGHT WITH SOUTH WINDS TO 10
KTS. LOW LEVEL WIND SHEAR INCLUDED IN TAFS BEGINNING 03-05Z TO
12-15Z TUESDAY AS LOW LEVEL JET WILL BE SCREAMING ABOVE INVERSION
AT UP TO 50 KTS.

FRONTAL BOUNDARY WILL APPROACH REGION OVERNIGHT WITH RAIN
DEVELOPING ACROSS WESTERN TERMINALS AROUND MIDNIGHT. PRECIP WILL
LIKELY START AS RAIN EXCEPT FOR A RAIN SNOW MIX NORTH AND EAST OF
PITTSBURGH WITH A PERIOD OF FREEZING RAIN EXPECTED AT KDUJ. AS
FRONT CROSSES REGION PRECIP WILL MIX BACK TO SNOW MID MORNING.

BEYOND PRECIP TYPE IFR CIGS WITH AND BEHIND FROPA WITH WINDS
TURNING SOUTHWEST AND GUSTY TO NEAR 25KT BEHIND FRONT LATE
AFTERNOON.

SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
SHORT TERM...WOODRUM
LONG TERM...RSMITH
AVIATION...RSMITH

AREA FORECAST DISCUSSION

NWS PITTSBURGH PA

1250 PM EST MON FEB 18 2013

.NEAR TERM /THROUGH TONIGHT/...
ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO ACCOUNT
FOR THE LATEST SKY TRENDS AND TO UPDATE WEATHER GRIDS FOR TONIGHT AND
TOMORROW.

THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A 500MB RIDGE AXIS
CENTERED OVER THE IN/OH BORDER. DRY AIR IN THE 1000-500MB LAYER IS
ADVECTING INTO THE AREA WITH THIS FEATURE WITH 450-250MB MOISTURE
ASSOCIATED WITH CIRRUS SPILLING OVER THE RIDGE AND INTO THE AREA.
AT THE SURFACE...A SURFACE LOW IS CENTERED ACROSS MINNESOTA WITH A
COLD FRONT EXTENDING SOUTHWARD ACROSS THE MISSOURI VALLEY AND INTO
THE SOUTHERN PLAINS. A WARM FRONT EXTENDS FROM A WEAKER LOW ALONG
THE FRONT IN IOWA EASTWARD INTO THE OHIO VALLEY.

TODAY...THE MID-LEVEL RIDGE WILL CROSS THE UPPER OHIO VALLEY AS A
WARM FRONT LIFTS NORTHWARD INTO THE AREA. ASIDE FROM CIRRUS CROSSING
THE AREA...EXPECT LIMITED CLOUD COVER TODAY. AFTER THE COLD
START...TEMPS WILL RESPOND NICELY TODAY...WITH WARMING AIDED BY
THE COMBINATION OF 850MB TEMPS INCREASING TO 2-4C WITH THE WARM
FRONT AND ABUNDANT SUNSHINE. TEMPS TODAY ARE FAIRLY CLOSE TO LAMP
GUIDANCE...WITH HIGHS RANGING FROM THE UPPER 30S ALONG THE I-80
CORRIDOR TO NEAR 50 IN PORTIONS OF EASTERN OHIO AND NORTH-CENTRAL
WV.

TONIGHT...SREF/WRF-ARW/WRF-NMM ARE IN AGREEMENT THAT MID-LEVEL
RIDGING WILL SHIFT EAST OF THE AREA TONIGHT WITH THE FRONT EDGE OF
PRECIPITATION AHEAD OF A COLD FRONT REACHING EASTERN OHIO BY AROUND
06Z. PRECIPITATION WILL HAVE TO OVERCOME AN INITIAL DRY LAYER...AND
BELIEVE THAT DYNAMIC COOLING/WET BULBING WITH THE SATURATION OF THIS
LAYER WILL ALLOW FOR SNOW AT THE ONSET OF THE EVENT FOR MOST
LOCATIONS EAST OF OHIO. 1000-500MB AND 1000-850MB CRITICAL THICKNESS
LINES WILL BE NORTH OF THE AREA TO BEGIN THE EVENT...HOWEVER WITH
THE FRONT MOVING INTO THE AREA...5400M/1300M LINES RESPECTIVELY
BOTH QUICKLY DROP SOUTHEAST OF THE AREA WITH THE FRONT.
THUS...INITIAL SLEET/SNOW WITH WET BULBING AND A CHANGE OVER TO
RAIN BY 12Z FOR THE LOWLANDS. FOR LOCATION NORTHEAST OF A
FRANKLIN-INDIANA LINE AND THE LAUREL HIGHLANDS/ALLEGHENY
FRONT...COLD AIR WILL BE DAMMED INTO THE AREA AND ALLOW FOR SOME
FZRA/SLEET TO OCCUR AFTER THE INITIAL SHOT SNOW AT THE ONSET.

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
NAM/GFS/ECMWF ARE IN REASONABLE AGREEMENT THAT AN UPPER LEVEL LOW
WILL MOVE ACROSS THE GREAT LAKES REGION ON TUESDAY...PUSHING THE
FRONT FROM EASTERN OHIO INTO WESTERN PA IN THE 12Z-18Z WINDOW WITH
THE FRONT SHIFTING EAST OF THE AREA IN THE 18Z-21Z WINDOW. MODELS
ARE IN REASONABLE AGREEMENT WITH ONE TO TWO TENTHS OF QPF. THE
MORE DIFFICULT FORECAST WILL BE PRECIP TYPE. A MODEL CONSENSUS HAS
THE 850MB 0C LINE WILL EXTEND FROM FRANKLIN TO PITTSBURGH TO
MORGANTOWN AT 12Z TUESDAY WITH CAA QUICKLY BRINGING TEMPS TO -4C
TO -10C ACROSS THE AREA BY 18Z. THUS...BELIEVE PRECIP WILL BE ALL
SNOW BY 18Z ACROSS THE AREA. HOWEVER...GFS/NAM TIME-HEIGHT CROSS-
SECTIONS ARE INDICATING THAT A 750-500MB DRY SLOT WILL BE CO-
LOCATED WITH THE DENDRITIC GROWTH ZONE FROM 15Z-21Z...MAKING
SPRINKLES OR DRIZZLE MORE LIKELY IN THAT PERIOD AND LIMITING
SNOWFALL. STILL...THE BIGGEST QUESTION IS...WITH THE FRONTAL
PASSAGE DURING THE DAY...HOW MUCH OF THE QPF WILL BE SNOW AND HOW
MUCH OF IT WILL ACCUMULATE BEFORE THE DRY SLOT ADVECTS INTO THE
AREA BEHIND THE FRONT. GIVEN THE DIURNALLY UNFAVORABLE PASSAGE
TIME...HAVE GONE WITH AN INCH OR LESS OF SNOW FOR LOCATIONS SOUTH
OF PITTSBURGH WITH 1 TO 2 INCHES NORTH AND EAST OF PITTSBURGH.

LOW PRESSURE ACROSS SOUTHEASTERN ONTARIO WILL MAKE SLOW PROGRESS
TO THE EAST DURING THE PERIOD. WINDS WILL GENERALLY BE
WESTERLY...ALLOWING FOR UPSLOPE SNOW TUESDAY NIGHT AND
WEDNESDAY...WITH MORE SCATTERED SNOW SHOWERS ELSEWHERE. THE
COMBINATION OF LOW INVERSION LEVELS AND A LACK OF MOISTURE DUE TO
ICE-COVERED LAKE ERIE SHOULD LIMIT HIGHEST SNOWFALL TOTALS TO 1-3
INCHES OVER THE 24 HOUR PERIOD. SNOW SHOWERS SHOULD BE FURTHER
DIMINISHED BY HIGH PRESSURE RIDGE SLIDING IN FROM THE WEST
WEDNESDAY NIGHT. BEHIND THE COLD FRONT...TEMPERATURES WILL RETURN
TO BELOW NORMAL VALUES.

.LONG TERM /THURSDAY THROUGH SUNDAY/...
SURFACE HIGH PRESSURE WILL BRING DRY CONDITIONS AND BELOW NORMAL
TEMPERATURES THURSDAY. A DEEP TROUGH ACROSS THE WESTERN CONUS
WILL CLOSE OFF INTO A LOW ACROSS THE NORTHERN PLAINS THURSDAY
NIGHT WITH AN OCCLUDING/OCCLUDED FRONTAL BOUNDARY APPROACHING THE
UPPER OHIO VALLEY. THIS FRONT WILL CROSS THE REGION LATER THURSDAY
NIGHT AND FRIDAY. LIKELY POPS AS THIS SYSTEM PASSES WITH SNOW TO A
MIX THEN RAIN AS THE FRONT PROGRESSES EASTWARD. REGION WILL THEN
BE IN WEAK COLD ADVECTION FRIDAY NIGHT INTO SATURDAY AS A
SECONDARY COASTAL LOW MAY FORM OFF OF NEW ENGLAND. SCATTERED RAIN
AND SNOW SHOWERS WILL DIMINISH BY LATE SATURDAY. HIGH PRESSURE
WILL THEN RETURN FOR DRY AND SEASONABLE CONDITIONS FOR SUNDAY.

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
VFR CONDITIONS INTO FIRST HALF OF TONIGHT WITH SOUTH WINDS TO 10
KTS. LOW LEVEL WIND SHEAR INCLUDED IN TAFS BEGINNING 03-05Z TO
12-15Z TUESDAY AS LOW LEVEL JET WILL BE SCREAMING ABOVE INVERSION
AT UP TO 50 KTS.

BEYOND PRECIP TYPE IFR CIGS WITH AND BEHIND FROPA WITH WINDS
TURNING SOUTHWEST AND GUSTY TO NEAR 25KT BEHIND FRONT LATE
AFTERNOON.

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

AREA FORECAST DISCUSSION

NWS PITTSBURGH PA

1156 AM EST MON FEB 18 2013

.NEAR TERM /THROUGH TONIGHT/...
ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO ACCOUNT
FOR THE LATEST SKY TRENDS AND TO UPDATE WEATHER GRIDS FOR TONIGHT AND
TOMORROW.

TONIGHT...SREF/WRF-ARW/WRF-NMM ARE IN AGREEMENT THAT MID-LEVEL
RIDGING WILL SHIFT EAST OF THE AREA TONIGHT WITH THE FRONT EDGE OF
PRECIPITATION AHEAD OF A COLD FRONT REACHING EASTERN OHIO BY AROUND
06Z. PRECIPITATION WILL HAVE TO OVERCOME AN INITIAL DRY LAYER...AND
BELIEVE THAT DYNAMIC COOLING/WET BULBING WITH THE SATURATION OF THIS
LAYER WILL ALLOW FOR SNOW AT THE ONSET OF THE EVENT FOR MOST
LOCATIONS EAST OF OHIO. 1000-500MB AND 1000-850MB CRITICAL THICKNESS
LINES WILL BE NORTH OF THE AREA TO BEGIN THE EVENT...HOWEVER WITH
THE FRONT MOVING INTO THE AREA...5400M/1300M LINES RESPECTIVELY
BOTH QUICKLY DROP SOUTHEAST OF THE AREA WITH THE FRONT.
THUS...INITIAL SLEET/SNOW WITH WET BULBING AND A CHANGE OVER TO
RAIN BY 12Z FOR THE LOWLANDS. FOR LOCATION NORTHEAST OF A
FRANKLIN-INDIANA LINE AND THE LAUREL HIGHLANDS/ALLEGHENY
FRONT...COLD AIR WILL BE DAMMED INTO THE AREA AND ALLOW FOR SOME
FZRA/SLEET TO OCCUR AFTER THE INITIAL SHOT SNOW AT THE ONSET.

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
HI PRES WL SLIDE EWD THRU THE MRNG AND SLY SFC WND WL RESUME AND
INCRS IN INTENSITY THRU THE DAY. OTHERWISE...VFR CAN BE EXPECTED
UNTIL RA AND SN PROBABILITIES INCRS LATE MON NGT/EARLY TUE WITH
THE APPRCH OF A COLD/OCCLUDING FRONT. LLWS POTENTIAL WL HAVE TO BE
MONITORED FOR THIS PD AS WELL. CONFIDENCE IS SUFFICIENT THIS MRNG IN
THE SYSTEMS STRUCTURE TO INCLUDE A MENTION IN TAFS.

.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
LINGERING RESTRICTIONS ARE ANTICIPATED THRU WED IN COLD NW FLOW
BEHIND THE FROPA. HI PRES AND VFR ARE EXPD THU...WITH PSBL
RESTRICTIONS FRI AS A WRMFNT JUMPS NWD ACRS THE RGN.

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

AREA FORECAST DISCUSSION

NWS MARQUETTE MI

956 PM EST TUE FEB 19 2013

.UPDATE...
ISSUED AT 955 PM EST TUE FEB 19 2013

MADE SOME CHANGES TO GOING HEADLINES...MAINLY DUE TO OBSVD VEERING
TREND IN LLVL WINDS AND EXPECTED SLOW DRYING FM THE W/DIMINISHING
WINDS AS DEEP LO TO THE E SLOWLY EXITS. OPTED TO EXTEND THE WRNG FOR
MQT COUNTY AND ADVY FOR DELTA COUNTY UNTIL 16Z WED TO ACCOUNT FOR
FVRBL 340-350 DEGREE FLOW AND WINDS SUFFICIENTLY STRONG TO BLOW
HEAVIER SHSN INTO DELTA COUNTY...ALL IN THE PRESENCE OF LINGERING
DEEP MSTR. WITH A MORE N WIND...CHANGED HEADLINE FOR LUCE COUNTY FM
A WRNG TO AN ADVY DUE TO SHORTER FETCH INTO THAT AREA. MAINTAINED
GOING BLIZZARD WRNG FOR THE KEWEENAW THRU 06Z AS WINDS ARE STILL
GUSTING AOA 50 MPH AT COPPER HARBOR...BUT ISSUED WINTER WX ADVY THRU
12Z TO ACCOUNT FOR LINGERING DEEP MSTR IN THAT AREA FCST UNTIL THAT
TIME THAT MIGHT CAUSE HEAVIER SHSN EVEN AS THE WINDS/BLSN SLOWLY
SUBSIDE AFT 06Z. ALSO EXTENDED THE ADVY FOR BARAGA COUNTY TO 12Z TO
ACCOUNT FOR LINGERING DEEPER MSTR THRU THAT TIME.

PER CALL TO MI STATE POLICE AT 9 PM...M-28 WILL REMAIN CLOSED BTWN
HARVEY AND MUNISING/WETMORE THRU THE NGT.
&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 430 PM EST TUE FEB 19 2013

WV IMAGERY AND RUC ANALYSIS INDICATED A NEG-TILT MID/UPPER LEVEL
TROUGH FROM HUDSON BAY THROUGH NW ONTARIO INTO WI/LOWER MI BEING
PROPELLED SLOWLY EAST BY A 110-120 KT 300-250 JET MOVG THROUGH THE
OHIO VALLEY TOWARD THE EASTERN LAKES IN THE BASE OF THE TROUGH.
THE BACK EDGE OF A WELL-DEFINED WARM CONVEYOR SHIELD EXTENDS BACK
INTO ERN LAKE SUPERIOR. MODERATE Q-VECT CONV COMBINED WITH NNW FLOW
ACROSS ERN LAKE SUPERIOR SUPPORTING WIND-PARALLEL LES BANDS OF
MODERATE TO HEAVY IN INTENSITY EAST OF MQT. TIGHT PRES GRADIENT ON
BACKSIDE OF 992 MB SFC LOW EAST OF LAKE SUPERIOR STILL MAINTAINING
HIGH GALE TO STORM FORCE WINDS OVER ERN HALF OF LAKE SUPERIOR.
STRONG WINDS AND MODERATE SNOW RESULTING IN BLIZZARD CONDITIONS OVER
THE KEWEENAW PENINSULA AND OVER ALGER COUNTY. STATE POLICE HAS
CLOSED M-28 BETWEEN HARVEY AND WETMORE DUE TO BLIZZARD CONDITIONS
AND IMPASSABLE ROAD CONDITIONS.

THE MODERATE 700-300 QVECTOR CONV AND DEEPER MOISTURE WILL LIFT
SLOWLY EAST WITH THE MOVEMENT OF SFC LOW TONIGHT. AS A RESULT LAKE
ENHANCED SNOW SHOWERS OVER ERN COUNTIES SHOULD SLOWLY
DIMINISH...ESPECIALLY OVERNIGHT INTO WEDNESDAY. DRIER AIR WORKING IN
OVER THE WRN PORTION OF LAKE SUPERIOR AS NOTED ON VIS SATELLITE HAS
GREATLY DIMINISHED LES OVER FAR WRN COUNTIES LATE THIS AFTERNOON.
THUS...HAVE DOWNGRADED WARNINGS TO WINTER WX ADVISORIES THIS EVENING
OVER GOGEBIC...ONTONAGON...BARAGA AND SRN HOUGHTON COUNTIES. WILL
CONTINUE BLIZZARD WARNINGS INTO THIS EVENING OVER THE KEWEENAW
PENINSULA AS WINDS GUSTING AOA 35 MPH WILL STILL CAUSE LOW
VISIBILITY AND TRAVEL DIFFICULTIES THERE. MARQUETTE COUNTY HAS SEEN
SNOW DIMINISH ACROSS MUCH OF THE AREA BUT LIGHT TO MODERATE LES
BANDS AND BLOWING SNOW...ESPECIALLY EAST OF MQT...WILL CONTINUE TO
CAUSE TRAVEL DIFFICULTIES INTO THE EVENING HRS SO KEPT WARNING GOING
FOR MQT COUNTY. CONTINUED DRYING FROM THE WEST SHOULD LEAD TO
IMPROVED CONDITIONS FOR MARQUETTE COUNTY WESTWARD LATE TONIGHT INTO
WEDNESDAY.

MOST PROLONGED HAZARDOUS CONDITIONS WILL BE FOR COUNTIES EAST OF MQT
WHERE WINDS GUSTING OVER 40 MPH AND MODERATE LES BANDS WILL
CONTINUE THE BLIZZARD TO NEAR BLIZZARD CONDITIONS THROUGH TONIGHT
AND POSSIBLY INTO WED MORNING. CONTINUED THE BLIZZARD WARNING FOR
ALGER COUNTY THROUGH MUCH OF WEDNESDAY DUE TO OCCASIONAL MODERATE
SNOW AND EXTREME BLOWING SNOW WITH STRONG NNW WINDS TO 35-40 MPH. AS
NOTED EARLIER...M-28 CLOSED BTWN HARVEY AND WETMORE DUE TO BLIZZARD
CONDITIONS. FAVORABLE SNOW GROWTH WITH DGZ WITHIN AREA OF BEST MODEL
OMEGA WILL ADD TO POOR VISIBILITY AND POTENTIAL FOR GREATER SNOWFALL
AMOUNTS TONIGHT INTO WED MORNING. MODEL AVG QPF ALONG WITH SLR FM
20-25/1 SHOULD YIELD 3-6 INCH SNOW AMOUNTS TONIGHT OVER ALGER AND
NRN SCHOOLCRAFT AND 2-5 INCHES OVER LUCE COUNTY AND SRN SCHOOLCRAFT.
DEEPER MOISTURE LEAVING THE AREA AND WEAKENING CYCLONIC NNW FLOW
WILL ALLOW LES TO GRADUALLY TAPER OFF BY WED AFTERNOON OVER ERN
COUNTIES WITH GENERALLY ADDITIONAL ACCUMS ON WED OF 2-4
INCHES.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 430 PM EST TUE FEB 19 2013

COMPARED TO WHAT WAS OCCURRING OUTSIDE TODAY...THE LONG TERM IS
GENERALLY QUIET THROUGH MUCH OF THE PERIOD.

LAKE EFFECT SNOW WILL BE SLOWLY DIMINISHING ON WEDNESDAY NIGHT AS
1040MB HIGH PRESSURE OVER NORTHERN ONTARIO CONTINUES TO PUSH A
SURFACE RIDGE OVER LAKE SUPERIOR. SUBSIDENCE ALOFT FROM THIS
HIGH WILL SLOWLY DROP THE INVERSION HEIGHTS OVER THE EASTERN
LAKE FROM AROUND 4KFT AT 00Z THURSDAY TO 2KFT AT 12Z. BUT...THERE
LOOKS TO BE ENOUGH MOISTURE SUB 900MB TO LEAD TO SOME LAKE EFFECT
SNOW IN THE NORTHERLY WIND LOCATIONS OF NORTH CENTRAL UPPER
MICHIGAN. NOT OVERLY IMPRESSED WITH THE THICKNESS OF THE CLOUD
LAYER...ONLY ABOUT 1-2KFT THICK...SO THERE MIGHT NOT BE MORE THAN
VERY LIGHT SNOW OR FLURRIES LATE WEDNESDAY NIGHT INTO THURSDAY
MORNING /MORE NORTHEAST WINDS THEN/ BEFORE THE DRIER AIR LOWERS THE
INVERSION AND SHOVES THE LINGERING CLOUDS TOWARDS THE SURFACE. AT
THAT POINT...IT WOULD LIKELY BE EITHER LOW CLOUDS OR MIX OUT FROM
DIURNAL MIXING INLAND.

THIS HIGH WILL REMAIN IN PLACE INTO THURSDAY NIGHT...AS A LOW
PRESSURE SYSTEM BEGINS TO EXIT THE CENTRAL PLAINS. MODELS NOT
SHOWING MUCH IN THE WAY OF STRENGTHENING OR WEAKENING AS THIS LOW
MOVES INTO THE GREAT LAKES ON FRIDAY AND THE UPPER GREAT LAKES ON
SATURDAY DUE TO IT BECOMING DETACHED FROM THE STRONGER SOUTHERN
STREAM JET. WITH IT PRECIPITATING ON IT/S WAY UP INTO THIS
AREA...BEING CUT OFF FROM THE GULF MOISTURE...AND RUNNING INTO DRY
AIR FROM THE CANADIAN HIGH...THE IDEA THE MODELS HAVE SHOWN FOR
SEVERAL DAYS OF THE SNOW DIMINISHING AS IT MOVES INTO THE GREAT
LAKES AREA SEEMS REASONABLE. WOULD EXPECT THE LIGHT SNOW TO MOVE
INTO THE AREA ON FRIDAY MORNING AND CONTINUE INTO THE DAY ON
SATURDAY. TOTAL QPF THROUGH THE 36 HOUR PERIOD LOOKS TO BE AROUND
0.25-0.4 INCH. ESTIMATED SNOW RATIOS AROUND 15 TO 1 AT THIS POINT
WOULD LEAD TO 4-6 INCHES OF SNOW OVER MUCH OF THE AREA DURING THAT
PERIOD. THIS WOULD LIKELY BE BELOW ADVISORY CRITERIA...ALTHOUGH SOME
LOCATIONS COULD NEAR THE 3 INCH IN 12 HOUR MARK DURING THE DAY ON
FRIDAY...ESPECIALLY TOWARDS THE WISCONSIN BORDER.

ONCE THIS SYSTEM DEPARTS TO THE EAST ON SATURDAY NIGHT...HIGH
PRESSURE AND UPPER RIDGING WILL MOVE INTO THE AREA AND LEAD TO A
QUIET AND DRY END TO THE WEEKEND AND LIKELY INTO MONDAY. 850MB TEMPS
SHOULD BE WARMER THAN -10C AND THUS WOULDN/T EXPECT ANY CONCERN FOR
LIGHT LAKE EFFECT ON SUNDAY...ESPECIALLY SINCE WINDS WILL BE BACKING
TO THE SOUTH AND PULLING WARMER AIR OVER THE AREA FOR SUNDAY NIGHT.

ATTENTION THEN TURNS TO THE NEXT WAVE EXITING THE FOUR CORNERS
REGION ON SUNDAY NIGHT AND MOVING TOWARDS THE GREAT LAKES ON MONDAY
INTO TUESDAY. AS IS TRADITIONALLY THE CASE...THE GFS IS ON THE FAST
SIDE WITH THE SYSTEM AND HAVING IT ARRIVE ON MONDAY...WHILE THE
ECMWF IS MORE TOWARDS TUESDAY/WEDNESDAY. THERE ARE ALSO DIFFERENCES
IN THE EXACT TRACK...SO WILL JUST MENTION CHANCE/SLIGHT POPS AT
THIS POINT.

AS FOR TEMPERATURES...EXPECT TO SEE A GRADUAL WARMING TREND FOR THE
SECOND HALF OF THE WORK WEEK...WITH HIGHS THIS WEEKEND AND INTO THE
FIRST PART OF NEXT WEEK AT OR SLIGHTLY ABOVE NORMAL.
&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 639 PM EST TUE FEB 19 2013

CMX...EXPECT PREDOMINANT LIFR WITH OCNL VLIFR CONDITIONS THIS EVNG
TO MODERATE TO IFR OVERNGT AS THE STRONG NNW WIND DIMINISHES/BLSN
SUBSIDES A BIT FOLLOWING SLOW EXIT OF DEEP LO PRES TO THE E. THE
ARRIVAL OF DRIER AIR/CONTINUED WEAKENING WINDS ON WED WL ALLOW
CONDITIONS TO IMPROVE TO MVFR.

IWD...EXPECT LIFR CONDITIONS WITH SN/BLSN TO IMPROVE A BIT TO IFR BY
MIDNGT WITH ARRIVAL OF DRIER AIR/SLOWLY WEAKENING WINDS/SUBSIDING
BLSN. CONTINUED DRYING/WEAKENING WINDS ON WED WL ALLOW CONDITIONS TO
IMPROVE TO MVFR.

SAW...EXPECT PREDOMINANT IFR/OCNL MVFR CONDITIONS THRU TNGT TO GIVE
WAY TO MVFR CONDITIONS ON WED WITH ARRIVAL OF DRIER AIR/SLOWLY
WEAKENING WINDS/DIMINISHED BLSN.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 430 PM EST TUE FEB 19 2013

STRONG WRAPPED UP SFC LOW EAST OF LAKE SUPERIOR WILL HEAD TOWARD
WESTERN QUEBEC TONIGHT WHILE BEGINNING TO WEAKEN. VERY TIGHT
PRESSURE GRADIENT PRESENT THROUGH THIS EVENING COMBINED WITH COLD
AIR ADVECTION AND STRONG WINDS ALOFT WILL MAINTAIN STRONG GALES WITH
FREQUENT STORM FORCE GUSTS OVER THE EASTERN HALF OF LK SUPERIOR
THROUGH THIS EVENING. EXTENDED STORM WARNINGS FOR LSZ266 THROUGH
THIS EVENING. WINDS WILL BE SLOW TO DIMINISH WITH GALES PERSISTING
OVER CENTRAL AND ERN LK SUPERIOR THROUGH WED. HEAVY FREEZING SPRAY
WILL CONTINUE THROUGH THURSDAY MORNING. HIGH PRESSURE CROSSING ON
THURSDAY WILL ALLOW WINDS TO RELAX AND HEAVY FREEZING SPRAY TO
SUBSIDE. EXPECT EAST WINDS 20-30 KTS ON FRIDAY INTO FRIDAY NIGHT AS
LOW PRESSURE MOVES IN FROM THE CENTRAL PLAINS. WINDS FOR THE
UPCOMING WEEKEND NO MORE THAN 20 KTS AS WEAK PRESSURE GRADIENT
PREVAILS.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT
FOR MIZ002-009-084.

WINTER STORM WARNING UNTIL 5 PM EST WEDNESDAY FOR MIZ014-085.

WINTER WEATHER ADVISORY FROM 1 AM TO 7 AM EST WEDNESDAY FOR
MIZ001-003.

BLIZZARD WARNING UNTIL 1 AM EST WEDNESDAY FOR MIZ001-003.

BLIZZARD WARNING UNTIL 5 PM EST WEDNESDAY FOR MIZ006.

WINTER WEATHER ADVISORY UNTIL 5 PM EST WEDNESDAY FOR MIZ007.

WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR MIZ004.

WINTER STORM WARNING UNTIL 11 AM EST WEDNESDAY FOR MIZ005.

WINTER WEATHER ADVISORY UNTIL 11 AM EST WEDNESDAY FOR MIZ013.

LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ THURSDAY
FOR LSZ162-240>251-263-265-267.

GALE WARNING UNTIL 7 PM EST WEDNESDAY FOR LSZ245>251-265>267.

HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST THURSDAY FOR LSZ264-
266.

GALE WARNING UNTIL 1 PM EST WEDNESDAY FOR LSZ243-244-264.

GALE WARNING UNTIL 5 AM EST /4 AM CST/ WEDNESDAY FOR LSZ240>242-
263.

LAKE MICHIGAN...
GALE WARNING UNTIL 7 AM EST WEDNESDAY FOR LMZ248-250.

UPDATE...KC
SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...KC
MARINE...VOSS

AREA FORECAST DISCUSSION

NWS MARQUETTE MI

640 PM EST TUE FEB 19 2013

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 430 PM EST TUE FEB 19 2013

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 430 PM EST TUE FEB 19 2013

COMPARED TO WHAT WAS OCCURRING OUTSIDE TODAY...THE LONG TERM IS
GENERALLY QUIET THROUGH MUCH OF THE PERIOD.

AS FOR TEMPERATURES...EXPECT TO SEE A GRADUAL WARMING TREND FOR THE
SECOND HALF OF THE WORK WEEK...WITH HIGHS THIS WEEKEND AND INTO THE
FIRST PART OF NEXT WEEK AT OR SLIGHTLY ABOVE NORMAL.
&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 639 PM EST TUE FEB 19 2013

SAW...EXPECT PREDOMINANT IFR/OCNL MVFR CONDITIONS THRU TNGT TO GIVE
WAY TO MVFR CONDITIONS ON WED WITH ARRIVAL OF DRIER AIR/SLOWLY
WEAKENING WINDS/DIMINISHED BLSN.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 430 PM EST TUE FEB 19 2013

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT
FOR MIZ002-004-009-013-084.

WINTER STORM WARNING UNTIL 5 PM EST WEDNESDAY FOR MIZ007-014-085.

BLIZZARD WARNING UNTIL 1 AM EST WEDNESDAY FOR MIZ001-003.

BLIZZARD WARNING UNTIL 5 PM EST WEDNESDAY FOR MIZ006.

WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR MIZ005.

LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ THURSDAY
FOR LSZ162-240>251-263-265-267.

GALE WARNING UNTIL 7 PM EST WEDNESDAY FOR LSZ245>251-265-267.

HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST THURSDAY FOR LSZ264-
266.

STORM WARNING UNTIL 11 PM EST THIS EVENING FOR LSZ266.

GALE WARNING UNTIL 1 PM EST WEDNESDAY FOR LSZ243-244-264.

GALE WARNING UNTIL 5 AM EST /4 AM CST/ WEDNESDAY FOR LSZ240>242-
263.

LAKE MICHIGAN...
GALE WARNING UNTIL 7 AM EST WEDNESDAY FOR LMZ248-250.

SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...KC
MARINE...VOSS

AREA FORECAST DISCUSSION

NWS MARQUETTE MI

1201 PM EST MON FEB 18 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 536 AM EST MON FEB 18 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
NE MANITOBA THROUGH THE PLAINS WITH SEVERAL EMBEDDED SHRTWVS. THE
MOST PROMINENT SHRTWVS OVER ERN ND AND WRN KS ALSO SUPPORTED SFC
LOWS INTO NRN MN AND CNTRL KS. SRLY FLOW HAD INCREASED OVER THE WRN
LAKES BTWN THE TROUGH TO THE WEST AND THE RIDGE THROUGH THE ERN
LAKES WITH KMQT/KGRB VAD WIND PRFL SHOWING 45KT 2K-3K FT WINDS. AN
AREA OF LIGHT SNOW THAT MOVED THROUGH CNTRL INTO ERN UPPER MI WAS
SUPPORTED BY A BAND OF 285K-290K ISENTROPIC LIFT. OTHERWISE...PCPN
AHEAD OF THE NRN SHRTWV REMAINED WELL TO THE WEST OVER NW MN.
UPSTREAM LOW LEVELS ALSO REMAINED RELATIVELY DRY WITH GENERALLY ONLY
MID/HIGH CLOUDS OVER WI AND SRN MN. THE ONLY EXECPTION WAS NEAR LAKE
MI WHERE SE WINDS PROVIDED ADDITIONAL MOISTURE FOR LOWER CLOUDS.

TODAY...AFTER THE LIGHT SNOW MOVES OUT OF THE ERN CWA...EXPECT
RELATIVELY QUIET CONDITIONS FOR MUCH OF THE DAY. SINCE MODELS LOW
LEVEL MOISTURE FCST HAVE BEEN TOO HIGH...PER UPSTREAM OB
TRENDS...CHANCES FOR ADDITIONAL PCPN WILL BE LOW UNTIL FORCING WITH
THE NRN STREAM SHRTWV NEARS LATER IN THE AFTERNOON.
NEVERTHELESS...THE SSE FLOW OFF OF LAKE MI MAY PROVIDE ENOUGH
MOISTURE FOR SOME PATCHY DZ/-DZ CNTRL AND EAST LATE THIS MORNING
INTO THE AFTERNOON UNTIL THE DEEPER MOISTURE ARRIVES. A BAND OF
800-600 MB FGEN WILL SUPPORT INCREASING CHANCE FOR SNOW INTO THE
WEST LATE

TONIGHT...MODEL DIFFERENCES REMAIN IN HANDLING INTERACTION/PHASING
OF THE SEPARATE STREAMS AND THE ASSOCIATED SFC LOW
DEVELOPMENT/POSITION. THE ECMWF/GFS AND ESPECIALLY THE GEM REMAINED
SLOWER AND MORE AGGRESSIVE IN STRENGTHENING THE LOW COMPARED THE NAM.
USING A GFS/ECMWF COMPROMISE...INCREASING 700-300 MB QVECTOR CONV
WITH THE NEG TILT TROUGH WOULD SUPPORT EXPANDING AND INTENSIFYING
AREA OF SNOW OVER THE EAST HALF OF UPPER MI. ALTHOUGH SLR VALUES ARE
ONLY IN THE 10/1 TO 15/1 RANGE ARE EXPECTED...QPF VALUES APPROACHING
A 0.25 TO 0.35 INCH COULD BRING AT LEAST 3 TO 4 INCHES OF SNOW
OVERNIGHT.

IN ADDITION THE STRONG MOIST CYCLONIC FLOW DRAWING IN MUCH COLDER
AIR ACROSS WRN LAKE SUPERIOR WILL SUPPORT SIGNIFICANT LAKE ENHANCED
SNOW INTO THE WEST...ESPECIALLY INTO THE HIGHER TERRAIN. SNOWFALL
AMOUNTS BY 12Z/TUE COULD ALREADY APPROACH 6 INCHES AS WINDS PRODUCE
AREAS OF BLOWING SNOW.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 536 AM EST MON FEB 18 2013

...HEAVY LAKE ENHANCED SNOW WITH STRONG WINDS/BLOWING SNOW TUESDAY
AND TUESDAY NIGHT AS WRAPPED UP LOW PRESSURE SYSTEM SLOWLY DEPARTS
UPPER LAKES...

CREDIT TO THE GEM-NH WHICH WAS SHOWING THIS TYPE OF WRAPPED UP SYSTEM
MANY DAYS AGO. SERIES OF H5 TROUGHS OVER THE NORTHERN ROCKIES THIS
MORNING FCST TO DIG INTO NORTHERN MN AND WI LATE TONIGHT THROUGH
TUESDAY MORNING. AS STRONG SHORTWAVE ROUNDS BASE OF TROUGH ALONG
WITH 250MB JET STREAKS LIFTING INTO ONTARIO AND LIFTING INTO LOWER
MICHIGAN...EXPECT SFC-H85 LOWS MOVING THROUGH TO DEEPEN. BASED ON
MODEL TRENDS...SEEMS LIKE WE ARE HEADING TOWARD MSLP BY 12Z TUESDAY
A BIT BLO 990MB...PERHAPS DOWN TO MID 980S MB. DUE TO COUPLED JET
STREAKS AND DIVERGENCE ALOFT ALONG WITH DEEPENING TROUGH...EXPECT
SWATH OF MODERATE TO HEAVY SNOW OVER MAINLY EAST CWA. H7 MIXING
RATIOS OVR 2.5G/KG AND QPF BULLSEYE OVR 0.25 INCH SUGGESTS ADDITIONAL
2-4 INCHES OF SNOW IN THE MORNING FROM MUNISING TO NEWBERRY AND MAYBE
AS FAR SOUTH AS MANISTIQUE. MEANWHILE...IN THE WEST AND NCNTRL
CWA...COLD AIR ADVECTION ON MOIST CYCLONIC FLOW LEADS TO PERIOD OF
SIGNIFICANT LAKE ENHANCED SNOW. MOISTURE PRESENT THROUGH AT LEAST
H7...THOUGH LIFT WITHIN THE LARGER SCALE IS LIMITED. SOUNDINGS DO NOT
SHOW TYPICAL OVERWHELMING INSTABILITY WITH HIGHER EQL AND LAKE
INDUCED CAPES AS INVERSION IS GENERALLY LESS THAN 6KFT THROUGH EVENT.
EVEN SO...H85 TEMPS FALLING TO -15C TO -20C BY 18Z TUESDAY WITH THE
SHARP CYCLONIC FLOW IN LOWEST LEVELS WILL OFFSET THIS AND LEAD TO THE
MODERATE TO HEAVY LAKE SNOWS. EXPECT 12HR SNOW AMOUNTS TOPPING OUT
AROUND 6 INCHES...BUT LOCALLY HEAVIER AMOUNTS MAY OCCUR...MAINLY IN
AREAS WITH ADDITIONAL UPSLOPE LIFTING GOING ON.

SNOW NOT ONLY ASPECT OF THE SYSTEM THOUGH...NOT BY A LONG SHOT.
WINDS AND BLOWING SNOW MAY BECOME QUITE SIGNIFICANT WITH THIS SYSTEM
BY TIME WE REACH LATER TUESDAY AND TUESDAY EVENING. DEEPENING LOW
PRESSURE AND BLYR WINDS 40 KTS+ ALONG WITH COLD AIR ADVECTION
RESULTS IN CONSIDERABLE BLOWING SNOW/POOR VSBY. WITHOUT DEEPER
MOISTURE THIS IMPACT WOULD BE LIMITED TO WHERE LAKE EFFECT BANDS
OCCUR. IN THIS SETUP THOUGH...ENVISION MORE WIDESPREAD SNOW WITH
POCKETS OF HEAVIER SNOW AND ENHANCED BLOWING SNOW. GIVEN EXPECTED
NNW BLYR WINDS...FAVORED AREAS WILL BE WESTERN CWA FROM IWD THROUGH
ROCKLAND AND TO TWIN LAKES AND ALSO OVR MOST OF EASTERN SNOWBELTS
FROM AU TRAIN TO NEWBERRY AND FARTHER EAST TOWARD THE SAULT. NORTH
FLOW MAY ALSO RESULT IN SEVERAL INCHES OF SNOW OVR HIGHER TERRAIN OF
KEWEENAW COUNTY AS WELL. WITH WIND AND SNOW...TRAVEL CONDITIONS OVER
MUCH OF UPR MICHIGAN WILL BE QUITE POOR MUCH OF TUESDAY AND TUESDAY
NIGHT.

TRENDS FROM MODELS TOWARD MORE AMPLIFIED SYSTEM /EVEN 00Z ECMWF IS
COMING ALONG TO THIS NOW/ ALONG WITH THE STRONG WIND FIELDS LED
TOWARD ISSUING WINTER STORM WARNINGS/ADVISORIES BEGINNING THIS
EVENING
ALONG ALL OF LK SUPERIOR AND INTO EASTERN CWA. LONG DURATION OF
DIFFICULT TRAVEL CONDITIONS EXPECTED WITH SOME SPOTS IN THE EAST NOT
SEEING IMPROVEMENT TIL LATER WEDNESDAY.

ONE OTHER NOTE...SINCE 925MB WINDS OF 35-40 KTS EXTEND AS FAR INLAND
AS IRON COUNTY TO DELTA AND SOUTHERN SCHOOLCRAFT COUNTIES AND THERE
IS LARGER SCALE MOISTURE...HEAVIEST SNOW AND BLSN IMPACTS MAY AFFECT
LOCATIONS FARTHER INLAND THAN NORMALLY WOULD OCCUR. DUE TO THIS
EXPECTATION PLACED HEADLINES UP FOR DELTA/SOUTHERN SCHOOLCRAFT.

REST OF LONG TERM...MINIMAL CHANGES AS FOCUS WAS CLEARLY ON UPCOMING
SYSTEM. DESPITE INVERSIONS BLO 5KFT LATE WED NIGHT INTO THURSDAY
EXPECT LGT LK EFFECT/FLURRIES WITH NORTH FLOW AND 925MB TEMPS BLO
-13C. NEXT SYSTEM STILL ON TRACK...IN A WEAKENING STATE...FOR FRIDAY
AND FRIDAY NIGHT. CHANCE POPS RETAINED FOR NOW. OTHERWISE...SLIGHT
WARMING TREND REMAINS IN STORE FOR NEXT WEEKEND WITH MAX TEMPS BACK
TO AROUND 30 DEGREES.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1201 PM EST MON FEB 18 2013

EXPECT MVFR CIGS THIS AFTERNOON AT SAW. SNOW IS EXPECTED TO
DEVELOP LATE THIS AFTERNOON AND EVENING WHICH WILL KEEP CONDITIONS
IN THE IFR RANGE AND THEN AS THE WIND PICKS UP LATE TONIGHT...VIS
SHOULD LOWER TO THE LIFR RANGE IN BLOWING SNOW.

AT IWD/CMX...CONDITIONS LATER IN THE DAY WILL ALSO FALL TO IFR
FOLLOWING PASSAGE OF A COLD FRONT...A WIND SHIFT TO AN UPSLOPE NW
WIND AND THE ONSET OF -SN. THE COMBINATION OF HEAVIER SNOW AND
INCREASING UPSLOPE NW WINDS ALONG WITH BLSN WILL LIKELY CAUSE LIFR
WX AT CMX/IWD TONIGHT INTO TUE MORNING.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 536 AM EST MON FEB 18 2013

SOUTH WINDS TO 30 KTS OVER FAR EASTERN SECTION TODAY THEN DEEPENING
LOW PRESSURE OVER UPR LAKES TONIGHT INTO TUESDAY MORNING RESULTS IN
NORTH-NORTHWEST GALES TO 45 KTS WITH POSSIBLE STORM FORCE GUSTS
THROUGH TUESDAY NIGHT. PERIOD OF STRONGEST WINDS FROM LATE TONIGHT
INTO TUESDAY MORNING OVER CNTRL LK SUPERIOR. LOW SLOWLY MOVES AWAY
BUT EXPECT GALES TO 35 KTS INTO WEDNESDAY. HIGH PRESSURE DROPPING IN
FROM CANADA RESULTS IN WINDS DIMINISHING TO LESS THAN 30 KTS
WEDNESDAY NIGHT AND THURSDAY. GALE WARNINGS POSTED WITH THIS SHIFT.
HEAVY FREEZING SPRAY OVER MOST OF THE LAKE THROUGH WEDNESDAY
NIGHT...SO PUT UP THOSE WARNINGS AS WELL. ANOTHER LOW PRESSURE
SYSTEM MOVES ACROSS UPR LAKES ON FRIDAY. EAST WINDS TO 30 KTS
EXPECTED FRIDAY AND FRIDAY NIGHT AS THE SYSTEM MOVES ACROSS.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING FROM 5 PM EST /4 PM CST/ THIS AFTERNOON TO
MIDNIGHT EST /11 PM CST/ TUESDAY NIGHT FOR MIZ002-009-084.

WINTER STORM WARNING FROM 7 PM THIS EVENING TO 5 PM EST
WEDNESDAY FOR MIZ006-007-014-085.

WINTER STORM WARNING FROM 5 PM THIS AFTERNOON TO 7 AM EST
WEDNESDAY FOR MIZ001-003.

WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO MIDNIGHT EST
TUESDAY NIGHT FOR MIZ004-005-013.

LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 7 AM EST /6 AM CST/ TUESDAY TO
7 AM EST /6 AM CST/ THURSDAY FOR LSZ162-240>251-263>267.

GALE WARNING FROM 5 AM TUESDAY TO 7 PM EST WEDNESDAY FOR
LSZ245>251-265>267.

GALE WARNING FROM MIDNIGHT TONIGHT TO 1 PM EST WEDNESDAY FOR
LSZ243-244-264.

GALE WARNING FROM 9 PM EST /8 PM CST/ THIS EVENING TO 5 AM EST
/4 AM CST/ WEDNESDAY FOR LSZ240>242-263.

GALE WARNING FROM 9 PM EST /8 PM CST/ THIS EVENING TO 1 PM EST
/NOON CST/ TUESDAY FOR LSZ162.

LAKE MICHIGAN...
GALE WARNING FROM 7 AM TUESDAY TO 7 AM EST WEDNESDAY FOR LMZ248-
250.

SHORT TERM...JLB
LONG TERM...JLA
AVIATION...07
MARINE...JLA

AREA FORECAST DISCUSSION

NWS MARQUETTE MI

746 AM EST MON FEB 18 2013

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 536 AM EST MON FEB 18 2013

...HEAVY LAKE ENHANCED SNOW WITH STRONG WINDS/BLOWING SNOW TUESDAY
AND TUESDAY NIGHT AS WRAPPED UP LOW PRESSURE SYSTEM SLOWLY DEPARTS
UPPER LAKES...

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 643 AM EST MON FEB 18 2013

THE COMBINATION OF GREATER MOISTURE INFLOW INTO THE REGION ON
INCREASING SOUTHERLY WINDS...BRIEF MOISTENINT WITH A BAND OF LIGHT
SNOW AND UPSLOPE SSE FLOW FROM LAKE MICHIGAN HAS LOWERED BROUGH IFR
CIGS INTO SAW. SO...EXPECT MAINLY IFR WITH POTENTIAL FOR SOME LOWER
END MVFR TO PERSIST THROUGH THE DAY. SNOW IS EXPECTED TO DEVELOP
LATE THIS AFTERNOON AND EVENING WHICH WILL KEEP CONDITIONS IN THE
IFR RANGE.