Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 02/19/13
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
321 PM PST MON FEB 18 2013
.SHORT TERM DISCUSSION...
BIG CHANGE IN THE W COAST PATTERN AS ENERGY DIGS INTO THE DEVELOPING
W COAST TROF AND A DEEP CLOSED LOW FORMS OVER NORCAL TUE AFTERNOON.
THE 500 MBS ANOMALY CHART INDICATES A MINUS 2 TO 3 ANOMALY OVER MUCH
OF CA A LITTLE STRONGER/DEEPER THAN THE PREVIOUS SYSTEM NEAR THE END
OF JAN. SIMILAR TO THAT SYSTEM...TPWS ASSOCIATED WITH THIS SYSTEM
ARE RATHER LOW. THE AMSU DATA IS SHOWING THIS MORNING`S .55 TO .65
INCH PW PLUME OFF THE COAST ERODING AS IT RUNS INTO THE MUCH LOWER
PW AIR OFF THE COAST. THE PW IS NOW A LOT LESS THAN 100 PERCENT OF
NORMAL. WHILE THE PWS ARE ROUGHLY THE SAME...IF NOT LOWER THAN THE
JAN STORM...THE STRONGER DYNAMICS AND COLDER INCOMING SYSTEM...ARE
STILL EXPECTED TO PARTIALLY OFFSET OR COMPENSATE FOR THE LACK OF
MOISTURE. THE GFS LAYER PW PROG SUGGESTED A BIT OF AN INCREASE IN
THE PW AS THE UPPER IMPULSE NEAR 50N/135W COMES DOWN LATER TONITE.
HOWEVER...WE ARE STILL NOT LOOKING AT A SIGNIFICANT QPF EVENT...
ALTHOUGH SNOW AMOUNTS WILL BENEFIT FROM THE COLD AIR AND ABOVE
NORMAL SNOW-LIQUID RATIOS.
ENHANCED CLOUDINESS IS BEGINNING TO DEVELOP ALONG THE N COAST...AND
WE STILL EXPECT A BAROCLINIC LEAF TO DEVELOP OVER NORCAL AS THE
UPPER IMPULSE NEAR 50N/135W DIGS INTO THE TROF AND INCREASES UPPER
LEVEL DIFFLUENCE AND ENHANCES UPWARD MOTION OVER OUR FORECAST
BETWEEN THE 12Z-18Z TUE TIME FRAME. THE 18/20Z RUC QPF RUN ENDING
07Z TUE DID NOT HAVE SIGNIFICANT QPF IN OUR CWA...SO THE 12Z-18Z
TIME FRAME ABOVE APPEARS TO BE A GOOD STARTING POINT FOR NOW. THE
ADVISORY TIMING MAY BE A LITTLE EARLY...BUT WE WOULD CHOOSE TO ERR
EARLIER RATHER THAN LATER.
STRONG CAA WILL STEEPEN LAPSE RATES BY TUE AFTERNOON RESULTING IN
THE POTENTIAL FOR VALLEY THUNDERSTORMS. THE LOWER TROPOPAUSE
CONDITIONS WILL RESULT IN LOW-TOPPED STORMS WITH MUCH...IF NOT
ALL...THE INSTABILITY BELOW 500 MBS. CAPE IS FORECAST TO BE VERY
MARGINAL FOR SEVERE POTENTIAL...ALTHOUGH THE SHEAR PARAMETERS
SUPPORT SOME STORM SCALE ROTATION DURING THE MID DAY PERIOD. GIVEN
THE LOW-TOPPED NATURE OF THE STORMS...THE 0-1 KM TOTAL SHEAR
PARAMETER IS MOSTLY FAVORED AS THE STORMS WILL BE ROOTED IN THE
BOUNDARY LAYER. GIVEN THE STRONG CAA...WE ARE NOT LIKELY TO WARM
INTO THE MID 60S AS IN THE 2005 PRESIDENTS DAY/WASHINGTON BIRTHDAY
HOLIDAY TORNADO DAY. IN ADDITION...PWS WERE MUCH HIGHER...AND THE
UPPER JET WAS IN A MORE FAVORABLE POSITION THEN. A MORE MERIDIONAL
JET IS FORECAST FOR TUE.
SNOW LEVELS ARE EXPECTED TO BE LOWER WITH THIS SYSTEM...LOWERING
INTO THE FOOTHILL LOCATIONS. EVEN THIS MORNING`S BUFKIT FORECAST
SOUNDINGS WERE SUGGESTING SNOW AT RDD AND RBL. RDD WE CAN UNDERSTAND
BECAUSE THE BUFR POINT IS ACTUALLY FARTHER N THAN THE AIRPORT...BUT
RBL IS A SURPRISE. USING THE TOP-DOWN REMINDER FOR PRECIP TYPE...WE
MAY BE LOOKING AT A MIX OR GRAUPEL SHOWERS. THIS SEEMS THE BETTER
SCENARIO...AS THE HEAVIER SHOWERS/THUNDERSTORMS ARE LIKELY TO
CONTAIN SMALL HAIL OR GRAUPEL AS WELL.
A BREAK IN THE WX ON WED...BEFORE THE NEXT WAVE SLIDES SWD WED NITE
AND EARLY THU. THE GFS KEEPS THIS SYSTEM OFFSHORE...WHILE THE ECMWF
HAS A MORE SUBTLE FEATURE COMING DOWN IN THE NWLY FLOW. FOR
NOW...WE LEANED TOWARDS THE EURO SOLUTION. THERE IS ACTUALLY
BETTER MODEL AGREEMENT IN THE FRI NITE SYSTEM. JHM
.EXTENDED DISCUSSION (FRIDAY THROUGH MONDAY)
UNSETTLED WEATHER CONTINUES INTO NEXT WEEKEND AS A COUPLE MORE
WAVES MOVE THROUGH THE AREA. THE FIRST WAVE IS EXPECTED FRIDAY NIGHT
INTO SATURDAY BRINGING A THREAT OF RAIN TO INTERIOR NORTHERN
CALIFORNIA. ALTHOUGH THE MODELS VARY WITH THE TIMING WITH THE
ECMWF SLOWER AND DEEPER WITH THE TROUGH THAN THE GFS SO CONFIDENCE
ON TIMING AND DETAILS STILL LOW. THE NEXT WAVE IS EXPECTED TO
BRUSH THE NORTH LATE SUNDAY INTO MONDAY CONTINUING THE THREAT OF
PRECIPITATION OVER THE MOUNTAINS AND THE NORTHERN SACRAMENTO
VALLEY. THERE IS UNCERTAINTY IN THE TIMING AND DETAILS OF THIS
SYSTEM. MAXIMUM TEMPERATURES ARE EXPECTED TO BE NEAR TO A LITTLE
BELOW NORMAL WITH HIGHS IN MID 50S TO LOW 60S IN THE VALLEY AND
30S TO 40S IN THE MOUNTAINS. MINIMUM TEMPERATURES ARE EXPECTED TO
BE NEAR TO BELOW NORMAL WITH LOWS IN THE MID 30S TO LOW 40S IN THE
VALLEY AND TEENS TO 20S IN THE MOUNTAINS.
&&
.AVIATION...
LOW PRES FM GOA WL MOV ACRS INTR NORCAL TUE INTO TUE NGT. DTRTG
CONDS OVR NRN INTR MTN WITH AREAS MVFR/IFR AFT 06Z SPRDG S AND BCMG
WDSPRD OVR ALL OF INTR NORCAL TUE MRNG. LCL LIFR CONDS...MNLY OMTNS.
SN LVLS LWRG TO ARND 015 AMSL...LCLY LWR...OVR SHASTA CNTY TUE AND
MNLY ARND 025 AMSL ELSW. ISOLD TSRA/TSRAGS POSS IN CNTRL VLY TUE
AFTN/EVE. AREAS S-SW SFC WND GSTS TO 30 KTS OR GTR...GENLY OVR HYR
MTN TRRN...TNGT AND TUE.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 4 AM TO 11 PM PST TUESDAY ABOVE
2000 FEET FOR THE MOTHERLODE...NORTHEAST FOOTHILLS/SACRAMENTO
VALLEY...WEST SLOPE NORTHERN SIERRA NEVADA...WESTERN PLUMAS
COUNTY/LASSEN PARK.
WINTER WEATHER ADVISORY FROM 2 AM TO 6 PM PST TUESDAY ABOVE 2000
FEET FOR THE CLEAR LAKE/SOUTHERN LAKE COUNTY...MOUNTAINS
SOUTHWESTERN SHASTA COUNTY TO NORTHERN LAKE COUNTY...SHASTA LAKE
AREA / NORTHERN SHASTA COUNTY.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1010 PM EST MON FEB 18 2013
.UPDATE...
THE NEAR TERM SECTION HAS 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 /TONIGHT/...
ISSUED AT 1010 PM EST MON FEB 18 2013
RADAR TRENDS THIS EVENING ARE SHOWS IN COLD FRONT IN PLACE ACROSS
EASTERN ILLINOIS...PUSHING EAST. PLENTIFUL RAINFALL WAS FOUND
AHEAD OF THE FRONT OVER CENTRAL INDIANA. BASED UPON RADAR TRENDS
PRECIPITATION WILL END OVERNIGHT AS THE FRONT PASSES TO OUR EAST.
00Z 850MB ANALYSIS SHOWS STRONG CAA POISED TO PUSH INTO INDIANA IN
THE WAKE OF THE FRONT WITH 850MB TEMPS OF LESS THAN -8C POISED TO
ARRIVE BY DAYBREAK. WITH SURFACE TEMPS UPSTREAM ALREADY IN THE
LOWER 20S AND EVEN THE TEENS IN EAST CENTRAL IA...HAVE TRENDED
LOW TEMPS COOLER.
LIGHTNING DETECTION DATA FAILS TO SHOW ANY STRIKES IN OR NEAR THE
STATE. HAVE REMOVED THUNDER ALSO.
&&
.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 19/0300 TAF UPDATE/...
ISSUED AT 921 PM EST MON FEB 18 2013
CURRENT TRENDS INDICATE THE COLD FRONT ADVANCING ACROSS ILLINOIS
MORE QUICKLY THAN ANTICIPATED. THEREFORE...HAVE BUMPED UP THE WIND
SHIFT ARRIVAL AT ALL TERMINALS...AT KLAF BY 05Z AND THROUGH KIND BY
07Z. HOWEVER...LEFT THE TIMING OF THE CHANGEOVER TO -SN TO BE A
LITTLE LATER THAN THE WIND SHIFT IN ORDER TO ALLOW THE BOUNDARY
LAYER TO COOL ENOUGH.
RELATIVE PREVIOUS DISCUSSION FOLLOWS...
CONDITIONS WILL CONTINUE TO DETERIORATE THIS EVENING AS RAINFALL AND
ASSOCIATED MVFR CEILINGS MOVE FROM WEST TO EAST ACROSS CENTRAL
INDIANA.
WINDS CONTINUE TO GUST TO AROUND 30 KTS AND LOOK TO INCREASE
SLIGHTLY LATE THIS EVENING AS THE 850 MB JET MOVES OVERHEAD. THE
JET COULD ALSO AID IN SOME INTENSIFICATION OF THE RAINFALL SO HAVE
BROUGHT IN SOME MVFR VISIBILITIES BY 03-06Z. HRRR ALSO DEPICTS A
BIT OF A STRENGTHENING TREND TO GO ALONG WITH THIS THINKING.
A COLD FRONT IS PROGGED TO PASS THROUGH THE TERMINALS IN THE
05-07Z TIME FRAME. CONTINUED THE MENTION OF SOME -SN BEHIND THE
FRONT AS MUCH COLDER AIR WILL BE USHERED INTO THE REGION WITH THE
SWITCH TO NORTHWESTERLY WINDS.
PRECIPITATION SHOULD MOVE OUT OF ALL THE TERMINALS BY SUNRISE
TUESDAY MORNING WITH STRONG NORTHWEST WINDS AND GUSTS TO 30 KTS
REMAIN.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CP
NEAR TERM...PUMA
SHORT TERM...CP
LONG TERM....RYAN
AVIATION...LEE
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
921 PM EST MON FEB 18 2013
.UPDATE...
THE AVIATION SECTION HAS 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 19/0300 TAF UPDATE/...
ISSUED AT 921 PM EST MON FEB 18 2013
CURRENT TRENDS INDICATE THE COLD FRONT ADVANCING ACROSS ILLINOIS
MORE QUICKLY THAN ANTICIPATED. THEREFORE...HAVE BUMPED UP THE WIND
SHIFT ARRIVAL AT ALL TERMINALS...AT KLAF BY 05Z AND THROUGH KIND BY
07Z. HOWEVER...LEFT THE TIMING OF THE CHANGEOVER TO -SN TO BE A
LITTLE LATER THAN THE WIND SHIFT IN ORDER TO ALLOW THE BOUNDARY
LAYER TO COOL ENOUGH.
RELATIVE PREVIOUS DISCUSSION FOLLOWS...
CONDITIONS WILL CONTINUE TO DETERIORATE THIS EVENING AS RAINFALL AND
ASSOCIATED MVFR CEILINGS MOVE FROM WEST TO EAST ACROSS CENTRAL
INDIANA.
WINDS CONTINUE TO GUST TO AROUND 30 KTS AND LOOK TO INCREASE
SLIGHTLY LATE THIS EVENING AS THE 850 MB JET MOVES OVERHEAD. THE
JET COULD ALSO AID IN SOME INTENSIFICATION OF THE RAINFALL SO HAVE
BROUGHT IN SOME MVFR VISIBILITIES BY 03-06Z. HRRR ALSO DEPICTS A
BIT OF A STRENGTHENING TREND TO GO ALONG WITH THIS THINKING.
A COLD FRONT IS PROGGED TO PASS THROUGH THE TERMINALS IN THE
05-07Z TIME FRAME. CONTINUED THE MENTION OF SOME -SN BEHIND THE
FRONT AS MUCH COLDER AIR WILL BE USHERED INTO THE REGION WITH THE
SWITCH TO NORTHWESTERLY WINDS.
PRECIPITATION SHOULD MOVE OUT OF ALL THE TERMINALS BY SUNRISE
TUESDAY MORNING WITH STRONG NORTHWEST WINDS AND GUSTS TO 30 KTS
REMAIN.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CP
NEAR TERM...CP
SHORT TERM...CP
LONG TERM....RYAN
AVIATION...LEE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
425 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 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 425 PM MST MON FEB 18 2013
VFR EXPECTED THROUGH THE PERIOD AT KGLD AND KMCK. GUSTY NORTHWEST
WINDS WILL QUICKLY DECREASE UNDER 10KTS BY 01Z AND SLOWLY BACK TO
THE WEST AND SOUTHWEST OVERNIGHT THEN SOUTHEAST BY MID AFTERNOON
TUESDAY AS A LOW PRESSURE SYSTEM STARTS TO APPROACH THE AREA. FOR
KGLD WIND GUSTS AROUND 25KTS WILL BE COMMON AFTER 17Z WHILE AT
KMCK EXPECT WINDS 10-15KTS WITH A FEW HIGHER GUSTS. CIGS AROUND 9K
FT EXPECTED EARLY TONIGHT BEFORE DISSIPATING. SOME CIRRUS TO MOVE
OVER FROM THE SOUTHWEST EARLY TUESDAY MORNING WITH SOME AFTERNOON
CU POSSIBLE AS WELL.
&&
.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...99
AREA FORECAST DISCUSSION
NWS TOPEKA KS
517 PM CST MON FEB 18 2013
...UPDATE TO AVIATION...
.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.
65
&&
.AVIATION...
23Z VIS SATELLITE SHOWING MVFR CONDITIONS MOVING OFF TO THE EAST
FOR TOP/FOE. FEW/SCT CONDITIONS UPSTREAM IN NEBRASKA...SO EXPECT
VFR CONDITIONS FOR MOST OF THE PERIOD. WIND GUSTS WILL DIMINISH
AFTER SUNSET AS HIGH PRESSURE MOVES IN.
BYRNE
&&
.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
305 PM MST SUN FEB 17 2013
.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 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1045 AM MST SUN FEB 17 2013
VFR CONDITIONS WILL PERSIST THROUGH THE TAF PERIOD AT GLD AND MCK.
WINDS WILL BE LIGHT OUT OF THE SOUTHWEST THIS AFTERNOON WITH HIGH
CIRRUS CLOUDS. THIS EVENING A STRONG COLD FRONT WILL PUSH THROUGH
BOTH TAF SITES WITH BREEZY TO GUSTY NORTHWEST WINDS TONIGHT AND
THROUGH TOMORROW. WINDS WILL BE 20-25KTS SUSTAINED OVERNIGHT INTO
TOMORROW WITH GUSTS UP TO 40KTS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...WIND ADVISORY FROM 8 PM MST /9 PM CST/ THIS EVENING TO 5 AM MST
/6 AM CST/ MONDAY FOR KSZ001>004-013>016-027>029-041-042.
RED FLAG WARNING UNTIL 6 PM MST /7 PM CST/ THIS EVENING FOR
KSZ002>004-013>016-027>029-041-042.
CO...WIND ADVISORY FROM 8 PM THIS EVENING TO 5 AM MST MONDAY FOR
COZ090>092.
RED FLAG WARNING UNTIL 6 PM MST THIS EVENING FOR COZ253-254.
NE...WIND ADVISORY FROM 8 PM MST /9 PM CST/ THIS EVENING TO 5 AM MST
/6 AM CST/ MONDAY FOR NEZ079>081.
&&
$$
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...JJM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
945 PM MST SAT FEB 16 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 144 PM MST SAT FEB 16 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE TROUGH ACROSS
WESTERN US WITH ITS AXIS CENTERED ALONG THE ROCKY MOUNTAINS...AND A
LARGE SCALE TROUGH ACROSS THE EASTERN US. A SHORTWAVE TROUGH
UPSTREAM OF THE H5 RIDGE IS DEEPENING OVER THE PACIFIC NW COAST.
THE H5 RIDGE IS EXPECTED TO SHIFT EAST WITH A VERY DRY AIRMASS
MOVING OVER OUR CWA. THE SHORTWAVE TROUGH UPSTREAM WILL DIG SOUTH
TOWARDS THE GREAT BASIN OVERNIGHT AND TOWARDS THE CENTRAL ROCKIES
MIDDAY. SURFACE GRADIENT WILL INCREASE AHEAD OF AN APPROACHING COLD
FRONT WITH WINDS INCREASING ACROSS THE SOUTHERN HALF OF THE CWA
THROUGH THE DAY. A PRE-FRONTAL TROUGH AXIS WILL MOVE INTO THE
NORTHERN HALF OF THE CWA DURING THE AFTERNOON HOURS SUNDAY WITH
WINDS DECREASING ALONG AND IMMEDIATELY BEHIND THIS FEATURE. WITH
STRONG WAA AND DEEP MIXING EXPECTED WE ARE LIKELY TO SEE NEAR RECORD
HIGH TEMPERATURES IN THE MID/UPPER 60S...POSSIBLY 70F.
VERY LOW TD VALUES ARE ALSO EXPECTED BY SUNDAY AFTERNOON...WITH RH
VALUES DROPPING TO RFW CRITERIA ACROSS MOST OF THE CWA DURING THE
AFTERNOON. WE COULD SEE SINGLE DIGIT RH VALUES IN THE SOUTH AND
WEST. AT THIS TIME...I AM MOST CONFIDENT IN WIND/RH CROSSOVER SOUTH
OF I-70 WHERE I HAVE ISSUED RED FLAG WARNING. WITH THE POSSIBILITY
OF WINDS DIMINISHING ACROSS THE NORTH...I AM NOT AS CONFIDENT IN
WIND/RH CROSSOVER...SO I ISSUED A FIRE WEATHER WATCH ACROSS THE
CENTRAL AND NORTHEASTERN PARTS OF THE CWA.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 219 PM MST SAT FEB 16 2013
LONG TERM FOCUS IS ON THE LOW PRESSURE SYSTEM MOVING EAST OF THE
ROCKIES AND ACROSS THE CENTRAL HIGH PLAINS REGION WEDNESDAY NIGHT
THROUGH THURSDAY NEXT WEEK.
SUNDAY NIGHT A COLD FRONT MOVES THROUGH THE REGION WITH THE UPPER
TROUGH MOVING THROUGH THE CENTRAL ROCKIES TO MOVE ACROSS THE
CENTRAL HIGH PLAINS BY MID DAY ON MONDAY. SINCE CONDITIONS WILL BE
MOSTLY DRY...EXPECT ONLY AN INCREASE IN CLOUDS AND COOLER
TEMPERATURES WITHOUT ANY PRECIPITATION. HIGH TEMPERATURES WILL BE
ABOUT 20 DEGREES COOLER ON MONDAY THAN THEY WERE ON SUNDAY. GUSTY
NORTHWEST WINDS ARE ALSO EXPECTED DURING THE DAY BEHIND THE FRONT.
SHORT WAVE RIDGING ALOFT IS EXPECTED ON TUESDAY AND TUESDAY NIGHT
IN THE WAKE OF THE EXITING TROUGH AND PRIOR TO THE NEXT
APPROACHING LOW PRESSURE CENTER DIVING SOUTH ALONG THE WEST COAST
THAT MOVES INTO THE FAR SOUTHWEST UNITED STATES BY WEDNESDAY
MORNING. A COOL HIGH PRESSURE AREA REMAINS OVER THE NORTHERN
PLAINS AND EXTENDS INTO THE CENTRAL PLAINS THROUGH
WEDNESDAY...TRANSPORTING LOW LEVEL MOISTURE INTO THE SOUTHERN AND
CENTRAL HIGH PLAINS REGIONS WITH THE POSSIBILITY OF A LITTLE
INSTABILITY MOVING OVER THE FORECAST AREA TO PRODUCE A MIX OF RAIN
AND SNOW SHOWERS AND POSSIBLY EVEN A RUMBLE OF THUNDER LATE IN THE
DAY ON WEDNESDAY IN THE WARM SECTOR AHEAD OF THE MAIN UPPER LOW
CENTER AS IT MOVES EAST OF THE ROCKIES IN THE VICINITY OF
SOUTHEAST COLORADO. HAVE LEFT THE MENTION OF THUNDER OUT FOR NOW.
RAIN TRANSITIONS TO SNOW OVERNIGHT WEDNESDAY NIGHT AND EARLY
THURSDAY MORNING AS COLDER AIR IS BROUGHT FURTHER SOUTH ACROSS THE
HIGH PLAINS. DEPENDING UPON THE TIMING OF THE CHANGE OVER TO SNOW
AND THE AMOUNT OF MOISTURE AND INSTABILITY THAT ACTUALLY AFFECTS
THE FORECAST AREA...THERE IS THE POTENTIAL FOR A SIGNIFICANT
SNOWFALL ACROSS THE CENTRAL HIGH PLAINS REGION MAINLY ACROSS THE
NORTHEAST HALF OF THE FORECAST AREA. IT`S STILL FAR ENOUGH OUT
THAT CONFIDENCE IS A LITTLE LACKING...BUT MODEL SOLUTIONS HAVE
BEEN ADVERTISING REASONABLY SIMILAR SOLUTIONS THROUGH THE LATTER
PORTIONS OF NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 945 PM MST SAT FEB 16 2013
VFR THROUGH THE PERIOD AT KGLD AND KMCK. W/SW WINDS UNDER 10KTS AT
THE START OF THE PERIOD WILL REMAIN SO THROUGH 17Z OR SO BEFORE
INCREASING AND BECOMING GUSTY FROM THE SOUTHWEST BY 19Z AND
CONTINUING THROUGH 23Z OR SO. PEAK GUSTS DURING THE AFTERNOON AT
KGLD AROUND 26KTS WITH 20KTS OR SO AT KMCK. COLD FRONT MOVES IN
AROUND 03Z AT BOTH TERMINALS WITH NW WINDS GUSTING 25-30KTS
THROUGH THE REMAINDER OF THE PERIOD. LITTLE TO NO CLOUDINESS
TIL CIRRUS INCREASE FROM THE NORTHWEST BY MID TO LATE AFTERNOON
WITH MID LEVEL CLOUDS BETWEEN 10-15K FT ARRIVING TOWARD THE END OF
THE TAF PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...RED FLAG WARNING FROM 11 AM MST /NOON CST/ TO 6 PM MST /7 PM
CST/ SUNDAY FOR KSZ027>029-041-042.
FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON
FOR KSZ003-004-013>016.
CO...RED FLAG WARNING FROM 11 AM TO 6 PM MST SUNDAY FOR COZ254.
FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON
FOR COZ253.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...99
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
828 PM EST MON FEB 18 2013
.Forecast Update...
Issued at 825 PM EST Mon Feb 18 2013
Updated the forecast to adjust POPs to the latest radar trends.
Rains are expected to continue to spread eastward this evening
making it to east central KY before Midnight. Slight t-storm
chances will be possible mainly over south central KY through
midnight judging by upstream lightning trends. Also wind gusts will
continue to remain strong in the 35-40 mph range at times through
this evening especially in moderate showers. According to the
latest RAP model, we should see the back edge of rains (very near
the cold front) enter southwest Indiana and west central KY between
8-10Z with steady rains moving out of east central KY by 15Z. After
rains move out of the area, colder air will filter into the region.
With low level moisture remaining in the area, we could see some
lingering flurries or drizzle on the back side of this weather
system tomorrow morning. Did make that adjustment to the weather
grids and adjusted sky cover as well.
&&
.Short Term (Tonight through Tuesday night)...
Issued at 310 PM EST Mon Feb 18 2013
Tight SSW gradient has established itself ahead of an approaching
cold front, so we have had an unseasonably mild and windy day across
the Ohio Valley. A decent band of showers has developed along the
axis of a 60-70 kt low-level jet and now extends from near
Effingham, IL to Memphis.
These showers should start to work into our western counties around
sunset and gradually push eastward. There have been a few lightning
strikes over the Mississippi Valley, but this far east it will be a
narrow and rapidly closing window for thunder. Will still mention
thunder west of I-65 this evening, but that is a very generous
forecast. Only factor in favor of thunder is the strength of the
low-level jet, as the better elevated instability will be to our
north and west, where low pressure will deepen as it is lifting from
central Missouri to Lake Michigan.
Still looking for a solid band of showers to move through, with the
best chances for precip just either side of midnight. Regardless of
thunder potential, the bigger story will be gusty winds, with 40 mph
gusts possible in and ahead of the line. Will mention this in the
HWO, and keep the Wind Advisory flying until 03Z.
Fropa expected in the pre-dawn hours on Tuesday, with POPs trending
downward quickly after that. As per usual, the cold air will be
chasing the moisture, so there is a possibility for precip to end as
snow showers or flurries on Tuesday morning, mainly north of I-64.
Blustery west winds will develop as high pressure builds from the
Plains, with sustained speeds around 15-20 mph and a few gusts
pushing 30 mph in a well-mixed boundary layer. Cold air advection
and lingering stratus, especially in the north, will limit any temp
recovery. Look for highs in the mid/upper 30s in Indiana, and mid
40s in south-central KY.
Clear and chilly Tuesday night as any lingering cloud cover will
dissipate quickly after sunset. Dewpoints will crash through the
teens, but just enough wind to keep temps from bottoming out. Will
dip into the teens in southern Indiana and the Bluegrass, with lower
to mid 20s elsewhere.
.Long Term (Wednesday - Monday)...
Issued at 300 PM EST Mon Feb 18 2013
An axis of Canadian high pressure will build across the Ohio Valley
as the center slides east across the Great Lakes Wednesday into
Thursday. Dry, yet cold conditions are expected. Highs Wednesday
will range from the low 30s across the north to upper 30s across the
south, with overnight lows dropping back into the upper teens and
low 20s.
Low pressure will develop early Thursday across western Kansas and
weaken as it moves northeastward through Illinois early Friday
morning. An occluded front will move toward central Kentucky by
early Friday and pass through the region during the day. Clouds will
increase by Thursday afternoon ahead of the system as warmer moist
air begins to overrun colder air near the surface. Appears the
majority of Thursday morning should be dry before precip starts to
saturate the very dry lower layers of the atmosphere. Models
continue to slow the arrival of the precip, which will take even
longer to reach the ground with dry air to overcome. Temperatures
will increase through the day Thursday, but believe some of that
warming will be initially offset by evaporative cooling. Forecast
soundings show a good chance of mixed wintry precipitation
developing Thursday afternoon as wet bulb temperatures hover on
either side of the freezing mark from just above the surface to
about 10K feet AGL. Will continue with the mix of rain and sleet
across our northern counties, but some light freezing rain may be
possible as well.
The good news is that eventually warm air advection will win out and
by the time precipitation becomes widespread by late Thursday
evening, the temperature profile supports rain as the main p-type
with no surface freezing. Given this scenario, expect a non-diurnal
temperature curve, with temperatures slowly rising through the day
Thursday, Thursday night, and Friday. High temperatures Friday are
expected to range from the upper 40s to mid 50s.
Precipitation should quickly come to an end during the day Friday,
as a strong upper jet streak moves eastward right along the Ohio
River and provides mid-level drying. Some low-level moisture will
likely be trapped below this mid-level dry air/inversion, so clouds
should linger. Another shortwave will quickly follow this system for
Friday night into Saturday, which will kick the entire trough
eastward. Some moisture could be pulled northward and provide rain
to mainly our southeastern counties. High temperatures Saturday will
range from the mid 40s in the north to mid 50s in the south.
Surface high pressure and shortwave ridging aloft will build across
the Ohio Valley late Saturday. Temperatures will warm and skies
will become partly cloudy. High temperatures Sunday will generally
fall within the low to mid 50s, with overnight lows in the mid to
upper 30s. Models are not in agreement on the arrival of our next
system, slated for either Sunday night through Monday (GFS) or
Monday into Tuesday (ECMWF). The main culprit seems to be how the
models are handling the strength of the downstream ridge, which
would be over our area. Will side with an ensemble approach, which
keeps a slightly more progressive pattern than the ECMWF, yet does
indicate enough amplification for a slower pattern than the GFS.
This solution would provide a chance of rain Monday, with highs in
the 50s.
&&
.Aviation (0Z TAF Issuance)...
Issued at 655 PM EST Mon Feb 18 2013
Gusty winds will continue this evening along with rain showers ahead
of an approaching cold front. In the leading band of rain working
into the TAF sites this evening through around 6Z...winds may gust
up to 35-40 kts as observed upstream. Also, BWG may experience a
VCTS before 6Z as well. Gusty winds of 25-35 kts will be present
though inside and outside of an t-storm. Also a strong LLJ from the
south around 45-50 kts will exist through 6Z making for a turbulent
airmass, however, felt this was still on the low side for a LLWS
mention. Plus, gusty low level winds are quite common in convective
showers.
MVFR cigs can be expected once the initial band of rain moves
through the area starting around 4-6Z although a period lower cigs
in moderate showers aren`t out of the question before then. The
fropa will occur between 10-11Z at all TAF sites veering winds from
SSW to W and remaining gusty between 20-25 kts. Flight conditions
should start to improve toward VFR at BWG during the mid to late
morning hours and at SDF/LEX later in the afternoon tomorrow.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...WIND ADVISORY UNTIL 10 PM EST /9 PM CST/ THIS EVENING FOR
INZ076>079-083-084-089>092.
KY...WIND ADVISORY UNTIL 10 PM EST /9 PM CST/ THIS EVENING FOR
KYZ023>043-045>049-053>057-061>067-070>078-081-082.
$$
Update...........AMS
Short Term.......RAS
Long Term........MJP
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1157 PM EST SAT FEB 16 2013
...Updated Aviation Discussion...
.Forecast Update...
Issued at 1100 PM EST Sat Feb 16 2013
Updated the forecast to adjust sky cover and temps as well as add
isld flurries to portions of southern Indiana and north central KY
in the area from Louisville to Lexington and northward. RAP
guidance has the best handle on low clouds this evening that have
been dropping southeastward through southern Indiana and portions of
north central KY. Therefore adjusted sky cover to account for these
recent trends. Also receiving some reports of flurries and even a
few snow showers in these low clouds. Don`t think any location will
see measurable precip from this shallow low level moisture, but did
insert isld flurries into the forecast for tonight. Also adjusted
temps to the HRRR model which depicts better cool/warm areas based
on the anticipated sky cover over northern sections of the forecast
area. This results in low temps in the mid to upper teens over much
of southern Indiana and central KY with locations in the Bluegrass
only falling into the upper teens and lower 20s since they will have
a longer period of mostly cloudy skies tonight.
&&
.Short Term (Now - Sunday)...
Issued at 310 PM EST Sat Feb 16 2013
An upper-level trough axis is currently passing over the forecast
area as it heads toward the east coast. With cold air advection,
temperatures struggled to rise this afternoon. Most places have
managed to at least reach the freezing mark and areas with more sun
have pushed mid 30s. As expected, snow showers developed along the
windward side of the Appalachians early this afternoon. These
showers will continue to push east with the trough and dissipate as
sunset nears.
Ridging at the surface and aloft will build across the Ohio Valley
starting tonight and shift east through the day Sunday. With the
center of the surface high passing by to our south, expect our
current breezy northwest winds to weaken and transition to westerly
for tomorrow and southerly by tomorrow night. Generally light winds
and partly cloudy skies tonight will allow temperatures to bottom
out in the mid teens to low 20s. Believe some low-level clouds will
build across at least a portion of the forecast area overnight,
which will keep some locations from reaching full radiational
cooling potential. Right now, have stretched this anticipated band
of clouds southeastward from Orange/Dubois counties in Indiana to
the Lake Cumberland region mainly after midnight, which is supported
by most hires guidance. There is some uncertainty to just how thick
the cloud deck will be, but this is where temps in the lower 20s are
likely. Of course, any shift in this cloud band will cause a shift
in temperatures as well. These clouds will quickly clear after
daybreak. A warming trend will commence tomorrow as increasing
temperatures/heights aloft, light west surface winds, and mostly
sunny skies push high temperatures to the middle 30s across the
Lexington area and to middle 40s across the Bowling Green area.
.Long Term (Sunday Night - Saturday)...
Issued at 300 PM EST Sat Feb 16 2013
Progressive longwave pattern aloft through the coming week will
provide a little bit of everything, with two main weathermakers on
Monday night and Thursday-Friday.
Modifying Canadian surface high will start to retreat east of
Kentucky on Sunday night, allowing return flow to start to develop.
However, we do expect a strong enough inversion that the effects
will be mostly aloft, so temps will still be near normal even after
leveling off by about midnight.
Monday will be unseasonably mild and breezy with the southerly flow
well established, and much of the day to warm up ahead of the
incoming precip shield. Most noticeable feature will be south winds
at a solid 20 mph with gusts in the 30s. This is below advisory
criteria but will keep the mention in the HWO. Max temps should be a
solid 10 degrees above climo. Will start to see showers ahead of the
front, with POPs ramping up in the afternoon, mainly west of I-65.
Look for a clean FROPA on Monday night, with categorical POPs and
QPF on the order of a half inch. Will be mild enough not to have
precip type issues, and stable enough to minimize any chance of
thunder. Can`t rule out some gusty showers, but even that is an
outside shot in the stable environment.
Minimal recovery in the cold advection on Tuesday as a 1040mb
Canadian high builds south toward Lake Superior. However, the
coldest air will remain bottled up in the Great Lakes and Canada,
with shortwave upper ridging over the Ohio Valley. Temps slightly
below normal, but by no means Arctic for Tue-Thu.
Next system will eject out of the southern Rockies on Thursday, but
will occlude over the Plains as a block develops along the East
Coast. The Ohio Valley will be in for stratiform warm frontal
precip, especially Thursday night where we will carry likely POPs.
Thermal profiles will be marginal, especially in our northern
counties. Expect it to be a race between the warmth and the
moisture, and confidence in the precip type forecast is quite low.
Temps will start below freezing throughout the area Thursday
morning, but it could take most of the day to saturate the column.
If precip arrives too quickly we could be looking at snow or
freezing rain, especially in the north and west. By Thursday night
it should be all rain across all but a few southern Indiana
counties. However, confidence in the precip type forecast is
currently too low to add any more value than the mention of rain or
snow, just as a heads-up to the possibility of mixed precip.
Pacific air mass will follow for the end of the week, with dry
weather and seasonable temps.
&&
.Aviation (6Z TAF Issuance)...
Issued at 1155 PM EST Sat Feb 16 2013
Sfc high pressure looks to dominate the region for this TAF period
with upper level ridging working eastward into the region through
tomorrow. The only minor TAF concern will be low VFR clouds moving
south into the SDF/LEX taf sites tonight. Although most of the cigs
are currently at low end VFR levels, some cigs upstream have dropped
to high end MVFR in isld snow showers. This looks most likely to
occur at LEX which was reporting a sct deck of 2700 ft with a snow
shower as of 4Z. High end MVFR and a snow shower could also happen
at SDF, but don`t think it`s as likely as LEX as SDF should remain
on the edge of the low cloud deck. Will monitor closely though and
amend if necessary.
A WNW wind is expected overnight probably remaining elevated around
5-7kts at SDF/LEX. Expect more westerly winds for tomorrow with
wind speeds maxing out in the 5-7 kt range during the afternoon
hours. Tomorrow evening, winds will shift to the SE ahead of the
next weather system.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........AMS
Short Term.......MJP
Long Term........RAS
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1108 PM EST SAT FEB 16 2013
.Forecast Update...
Issued at 1100 PM EST Sat Feb 16 2013
Updated the forecast to adjust sky cover and temps as well as add
isld flurries to portions of southern Indiana and north central KY
in the area from Louisville to Lexington and northward. RAP
guidance has the best handle on low clouds this evening that have
been dropping southeastward through southern Indiana and portions of
north central KY. Therefore adjusted sky cover to account for these
recent trends. Also receiving some reports of flurries and even a
few snow showers in these low clouds. Don`t think any location will
see measurable precip from this shallow low level moisture, but did
insert isld flurries into the forecast for tonight. Also adjusted
temps to the HRRR model which depicts better cool/warm areas based
on the anticipated sky cover over northern sections of the forecast
area. This results in low temps in the mid to upper teens over much
of southern Indiana and central KY with locations in the Bluegrass
only falling into the upper teens and lower 20s since they will have
a longer period of mostly cloudy skies tonight.
&&
.Short Term (Now - Sunday)...
Issued at 310 PM EST Sat Feb 16 2013
An upper-level trough axis is currently passing over the forecast
area as it heads toward the east coast. With cold air advection,
temperatures struggled to rise this afternoon. Most places have
managed to at least reach the freezing mark and areas with more sun
have pushed mid 30s. As expected, snow showers developed along the
windward side of the Appalachians early this afternoon. These
showers will continue to push east with the trough and dissipate as
sunset nears.
Ridging at the surface and aloft will build across the Ohio Valley
starting tonight and shift east through the day Sunday. With the
center of the surface high passing by to our south, expect our
current breezy northwest winds to weaken and transition to westerly
for tomorrow and southerly by tomorrow night. Generally light winds
and partly cloudy skies tonight will allow temperatures to bottom
out in the mid teens to low 20s. Believe some low-level clouds will
build across at least a portion of the forecast area overnight,
which will keep some locations from reaching full radiational
cooling potential. Right now, have stretched this anticipated band
of clouds southeastward from Orange/Dubois counties in Indiana to
the Lake Cumberland region mainly after midnight, which is supported
by most hires guidance. There is some uncertainty to just how thick
the cloud deck will be, but this is where temps in the lower 20s are
likely. Of course, any shift in this cloud band will cause a shift
in temperatures as well. These clouds will quickly clear after
daybreak. A warming trend will commence tomorrow as increasing
temperatures/heights aloft, light west surface winds, and mostly
sunny skies push high temperatures to the middle 30s across the
Lexington area and to middle 40s across the Bowling Green area.
.Long Term (Sunday Night - Saturday)...
Issued at 300 PM EST Sat Feb 16 2013
Progressive longwave pattern aloft through the coming week will
provide a little bit of everything, with two main weathermakers on
Monday night and Thursday-Friday.
Modifying Canadian surface high will start to retreat east of
Kentucky on Sunday night, allowing return flow to start to develop.
However, we do expect a strong enough inversion that the effects
will be mostly aloft, so temps will still be near normal even after
leveling off by about midnight.
Monday will be unseasonably mild and breezy with the southerly flow
well established, and much of the day to warm up ahead of the
incoming precip shield. Most noticeable feature will be south winds
at a solid 20 mph with gusts in the 30s. This is below advisory
criteria but will keep the mention in the HWO. Max temps should be a
solid 10 degrees above climo. Will start to see showers ahead of the
front, with POPs ramping up in the afternoon, mainly west of I-65.
Look for a clean FROPA on Monday night, with categorical POPs and
QPF on the order of a half inch. Will be mild enough not to have
precip type issues, and stable enough to minimize any chance of
thunder. Can`t rule out some gusty showers, but even that is an
outside shot in the stable environment.
Minimal recovery in the cold advection on Tuesday as a 1040mb
Canadian high builds south toward Lake Superior. However, the
coldest air will remain bottled up in the Great Lakes and Canada,
with shortwave upper ridging over the Ohio Valley. Temps slightly
below normal, but by no means Arctic for Tue-Thu.
Next system will eject out of the southern Rockies on Thursday, but
will occlude over the Plains as a block develops along the East
Coast. The Ohio Valley will be in for stratiform warm frontal
precip, especially Thursday night where we will carry likely POPs.
Thermal profiles will be marginal, especially in our northern
counties. Expect it to be a race between the warmth and the
moisture, and confidence in the precip type forecast is quite low.
Temps will start below freezing throughout the area Thursday
morning, but it could take most of the day to saturate the column.
If precip arrives too quickly we could be looking at snow or
freezing rain, especially in the north and west. By Thursday night
it should be all rain across all but a few southern Indiana
counties. However, confidence in the precip type forecast is
currently too low to add any more value than the mention of rain or
snow, just as a heads-up to the possibility of mixed precip.
Pacific air mass will follow for the end of the week, with dry
weather and seasonable temps.
&&
.Aviation (0Z TAF Issuance)...
Issued at 615 PM EST Sat Feb 16 2013
Sfc high pressure looks to dominate the region for this TAF period
with upper level ridging working eastward into the region through
tomorrow. The only minor TAF concern will be clouds over central IN
that are progged by the NAM and RAP to move south into the SDF/LEX
taf sites tonight. Although most of the cigs up north are currently
at low end VFR levels, short range models suggests these cigs may
lower to between 2-4 kft tonight as they move into our region. The
best time for this to happen looks to be between 1Z-10Z overnight.
Still not confident that the whole cloud deck over central IN won`t
drift farther east and miss the terminals completely and not sure
how solid the deck will be after a portion of it dissipates due to
loss of afternoon instability. Therefore, went with a bkn035 deck
at this time. Will monitor closely this evening and amend if
necessary.
Wind gusts should be declining shortly with a WNW wind expected
overnight probably remaining elevated around 7kts at SDF/LEX.
Expect more westerly winds for tomorrow with wind speeds maxing out
in the 5-7 kt range during the afternoon hours.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........AMS
Short Term.......MJP
Long Term........RAS
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
936 PM EST MON FEB 18 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION ON TUESDAY. HIGH PRESSURE WILL
RETURN TO THE AREA BOTH WEDNESDAY AND THURSDAY. A WAVE OF LOW
PRESSURE MAY BRING ANOTHER WINTRY MIX TO THE MID-ATLANTIC REGION
BEGINNING ON FRIDAY AND POSSIBLY CONTINUING INTO THE FIRST PART OF
THE WEEKEND.
&&
.NEAR TERM /THROUGH TUESDAY/...
LOPRES NEAR MKE AT 02Z...W/ ATTENDENT CDFNT SWD TO PAH. PCPN AHD
OF SYSTEM TO IND AND BNA. ONLY A FEW HIGH THIN CLDS AFFECTING AREA
THIS EVNG. SATPIX SUGGEST THAT WL BE THE CASE PAST MIDNGT. HWVR...
DO NOT XPCT MUCH MORE DCPLG AS SLY FLOW INCR OVNGT. THUS...TEMPS
SHUD LVL OFF BY/SOON AFTR MIDNGT.
18Z AND NOW 00Z GDNC HAS FLLWD TRENDS FM THE 12Z CYCLE FOR
PROGRESSION OF STORM SYSTEM. NAM AND ITS DERIVATIVES ABT 3 HRS
SLOER THAN GFS AND ASSOCD WRFS. RAP IN BTWN...BUT CLSR TO NAM. NAN
FCST DOESNT BRING PCPN TO I-95 TIL 17Z. GOING FCST ALREADY
EMPLOYING COMPROMISE...SO ADJUSTMENTS MADE THIS EVNG HV BEEN
MINOR. ANY DELAY IN ONSET WL BE FVRBL IN TERMS OF PTYPE...IE RAIN
VS SOMETHING WINTRY. ALSO NOTED IN MDL GDNC AND SNDGS IS A
RELATIVELY THICK COLD LYR IN THE MTNS. FURTHER...THE DRY LLVLS WUD
FAVOR EVAP COOLING/WET-BULB EFFECTS...WHICH WUD SUPPORT MORE SNW
INSTEAD OF FZRA.
SINCE THE PROFILE AND TIMING BOTH UNFAVORABLE FOR FZRA...WL NOT BE
ADDING TO CURRENT WINTER WX ADVY. HWVR...ACKNOWLEDGING THE SUBTLE
CHGS THAT CUD STILL HPPN...WL BE CONTG CURRENT ADVY AS IS.
BELIEVE PCPN WL REACH APLCHNS BY DAYBREAK...PRBLY AS SNPL...AND
MAKE IT TO I-95 BY MID-LT MRNG. MEANWHILE...STRONG WAA WL ERODE
LLVL COLD AIR...MAKING IT UNLKLY THAT ANYTHING OTHER THAN RA WL
FALL BY THE TIME PCPN REACHES THE BLURDG. THRU THE MID-LT MRNG...
THESE PROCESSES WL THEN GO TO WORK IN THE WEST...FIRST HITTING THE
RDG TOPS...THEN THE VLYS. AREAS OF THE PTMC HIGHLANDS WL BE LAST
TO CHG OVR TO RA. WHILE THERE CUD BE SOME SNPL ACCUMS IN THE W...
THEY WUD BE SUB-ADVY LVL.
A PERIOD OF RAIN WILL MOVE EAST ACROSS THE CWA THROUGH THE
AFTERNOON. CATEGORICAL POPS ARE IN PLACE OVER THE CWA. COLD
FRONTAL BOUNDARY WILL MOVE THROUGH FROM THE WEST...INITIATING A
WIND SHIFT LATE IN THE AFTERNOON ACROSS THE INTERSTATE 95
CORRIDOR.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/...
THE COLD FRONT WILL EXIT OFF THE MIDDLE ATLANTIC COAST LATER
TUESDAY WITH A COLDER AIRMASS FILTERING INTO THE REGION ON STIFF
WEST TO NORTHWEST WINDS. A TIGHT PRESSURE GRADIENT WILL SETUP
BEHIND THE BOUNDARY AS LOW PRESSURE MOVES ACROSS THE GREAT LAKES
AND HIGH PRESSURE BUILDS IN FROM THE WEST. GUSTY WINDS OVER 30 MPH
WILL BE POSSIBLE TUESDAY NIGHT INTO WEDNESDAY WITH STRONGER WINDS
EXPECTED OVER THE HIGHER TERRAIN. BELOW NORMAL HIGH TEMPERATURES
ARE EXPECTED ON WEDNESDAY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
WINDS WILL DIMINISH WEDNESDAY NIGHT AS HIGH PRESSURE RIDGES INTO
THE MIDDLE ATLANTIC. COLD TEMPERATURES WILL FOLLOW WEDNESDAY NIGHT
AS SKIES CLEAR AND BOUNDARY LAYER WINDS DECOUPLE. LOWS FROM THE
TEENS TO THE MIDDLE 20S WILL BE COMMON. THE HIGH WILL SHIFT EAST
THURSDAY GIVING WAY TO THE TROUGH AND FRONTAL BOUNDARY ON FRIDAY.
THIS SYSTEM ALSO REMAINS A CHALLENGE WITH REGARD TO TIMING AND
AMOUNT OF QPF. IT APPEARS THAT THERE WILL BE ENOUGH COLD AIR IN
PLACE FOR PRECIPITATION TO BEGIN AS SNOW OR A MIX WITH EARLY ON
FOLLOWED BY RAIN EAST OF THE BLUE RIDGE AND A POSSIBLE MIX IN
COLDER LOCALES TO THE NORTH AND WEST. EXTENDED MODELS CONTINUE TO
TREND TOWARD A COASTAL LOW DEVELOPING OVER THE CAROLINAS SATURDAY
INTO SUNDAY BUT AT THAT POINT THE AIRMASS COULD BE TOO WARM FOR
WINTRY PRECIPITATION. THE SITUATION BEARS WATCHING OVER THE NEXT
FEW DAYS.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
VFR OVNGT. PRECIPITATION IS EXPECTED TO DEVELOP TUESDAY MORNING.
HV DELAYED ONSET BY AN HR OR TWO...WHICH FAVORS RA A LTL MORE...
AND WINTRY PCPN A LTL LESS. BEST CHANCE OF S/PL LOOKS TO BE MRB. A
PERIOD OF PL ALSO POSSIBLE AT THE HUBS BEFORE CHANGING TO RAIN...
BUT HV OPTED TO REMOVE FROM TAF DUE TO TIMING ADJUSTMENT. MVFR
CONDITIONS ARE LIKELY WITH A CHANCE OF TEMPORARY IFR CONDITIONS
MAINLY LATE MORNING THROUGH MID AFTERNOON. COLD FRONT MOVES
THROUGH WITH A WIND SHIFT IN THE LATE AFTERNOON.
WINDY CONDITIONS AT ALL TERMINALS TUESDAY NIGHT AND WEDNESDAY WITH
VFR CIGS AND VSBYS EXPECTED. WINDS SUBSIDE WEDNESDAY NIGHT AND
THURSDAY FOLLOWED BY ADDITIONAL PROBABILITIES FOR WINTRY
PRECIPITATION FRIDAY INTO SATURDAY WITH SUB-VFR CONDITIONS.
&&
.MARINE...
SOUTHERLY FLOW DEVELOPS TONIGHT...AND WILL CHANNEL UP THE BAY.
GDNC STRONGLY POINTING AT THIS...AND SCA CONDS BEING REALIZED AT
TPLM2 ATTM. WL CONT SCA TO POOLES ISL INCL MOUTH OF THE PTMC
OVRNGT...AND WL CONTINUE OVER ALL WATERS INTO THE DAY ON TUESDAY.
COLD FRONT MOVES THROUGH LATE IN THE DAY WITH A WIND SHIFT TO THE
WEST.
SMALL CRAFT CONDITIONS...POSSIBLY GALE EXPECTED TUESDAY NIGHT INTO
WEDNESDAY. WINDS WILL DIMINISH WEDNESDAY NIGHT AND THURSDAY BUT
COULD INCREASE FRIDAY INTO SATURDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER WEATHER ADVISORY FROM 4 AM TO 11 AM EST TUESDAY FOR
MDZ501-502.
VA...WINTER WEATHER ADVISORY FROM 4 AM TO 11 AM EST TUESDAY FOR
VAZ503-504.
WV...WINTER WEATHER ADVISORY FROM 4 AM TO 11 AM EST TUESDAY FOR
WVZ501>506.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST WEDNESDAY FOR ANZ531>534-
537>543.
SMALL CRAFT ADVISORY FROM 9 AM TUESDAY TO 6 AM EST WEDNESDAY
FOR ANZ530-535-536.
&&
$$
SYNOPSIS...KRW
NEAR TERM...HTS/BPP
SHORT TERM...KRW
LONG TERM...KRW
AVIATION...BPP/HTS/KRW
MARINE...BPP/HTS/KRW
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
428 PM EST SUN FEB 17 2013
.SYNOPSIS...
SNOW SHOWERS WILL DECREASE IN COVERAGE THIS EVENING. HIGH PRESSURE
WILL THEN BUILD IN TONIGHT WITH A COLD NIGHT BEFORE DRY AND WARMER
WEATHER ARRIVING ON MONDAY. A COLD FRONT WILL THEN RETURN A WINTRY
MIX EARLY ON TUESDAY WITH SNOW SHOWERS IN ITS WAKE ON TUESDAY
NIGHT AND EARLY WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A MID-LEVEL TROUGH
AXIS CENTERED ACROSS THE JERSEY COAST...LEAVING THE UPPER OHIO
VALLEY IN A NORTHWESTERLY FLOW IN THE WAKE OF THIS FEATURE. AT
850MB...A NORTH-NORTHWESTERLY FLOW IS IN PLACE ACROSS THE
LOWLANDS...WITH MORE OF WESTERLY COMPONENT ACROSS THE LAUREL
HIGHLANDS AND ALLEGHENY FRONT OF WV/PA/MD. AT THE SURFACE...A LOW
PRESSURE SYSTEM IS OFF THE COAST OF NEW ENGLAND WITH A BROAD AREA
OF HIGH PRESSURE EXTENDING FROM THE UPPER MIDWEST TO THE GULF OF
MEXICO. THE COMBINATION OF WEAK VORT ENERGY SWINGING SOUTHEASTWARD
ON THE BACK END OF THE TROUGH ALONG WITH MOISTURE FILTERING IN
FROM LAKE HURON HAS ALLOWED SCATTERED SNOW SHOWERS TO CONTINUE
ACROSS MUCH OF THE AREA...WITH MORE NUMEROUS SNOW SHOWERS WITH
UPSLOPING ACROSS THE RIDGES. WITH THE LOSS OF HEATING AND MOISTURE
PULLING AWAY...SNOW SHOWERS ARE BEGINNING TO DIMINISH.
THIS EVENING...THE UPPER TROUGH WILL PUSH OFF THE EAST COAST
WITH THE AREA REMAINING IN A NORTHWESTERLY FLOW AS HIGH PRESSURE
BEGINS TO BUILD IN FROM THE SOUTHWEST. VORT ENERGY SLIDING
EASTWARD WILL ALLOW FOR SNOW SHOWERS TO CONTINUE TO DIMINISH WITH
MOISTURE BECOMING MORE SHALLOW AND AN INVERSION LOWERING THIS
EVENING...ALLOWING FOR SNOWFALL TO CONTINUE TO DECREASE IN
COVERAGE AND DIMINISH. UPSLOPING WILL ALLOW FOR ACCUMULATING
SNOWFALL TO CONTINUE IN THE EASTERN RIDGES...WITH AN ADDITIONAL
INCH THERE.
TONIGHT...HIGH PRESSURE WILL BUILD IN FROM THE SOUTHWEST WITH AN
850MB RIDGE MOVING INTO THE AREA AND BRINGING AN END TO LINGERING
UPSLOPING SNOWS FOR THE RIDGES. SKIES WILL CLEAR OUT WITH WINDS
DECREASING TO AROUND 5 MPH. WITH 850MB TEMPS AS COLD AS
16C...ALONG WITH CLEARING AND DECREASED WINDS CONTRIBUTING TO SOME
RADIATIONAL COOLING...LOWS TONIGHT WILL RANGE FROM THE SINGLE
DIGITS ACROSS THE HIGHER ELEVATIONS TO THE MID TEENS ACROSS THE
LOWLANDS.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
A MODEL CONSENSUS INDICATES A MID-LEVEL RIDGE CROSSING THE AREA ON
MONDAY WITH HIGH PRESSURE PASSING SOUTHWARD. THIS WILL ALLOW FOR A
DRY DAY WITH ABUNDANT SUNSHINE TO START THE DAY. AS A LOW-LEVEL
RIDGE SHIFTS EAST OF THE AREA...THE FLOW WILL BECOME
SOUTHWESTERLY AND ALLOW FOR WEAK WAA TO ENSUE. THIS ALONG WITH
SUNSHINE WILL CONTRIBUTE TO MAKE HIGHS A FEW DEGREES ABOVE
SEASONAL NORMALS ON MONDAY.
SOME UNCERTAINTY ENTERS THE FORECAST MONDAY NIGHT INTO TUESDAY AS
A COLD FRONT MOVES INTO THE REGION. GFS/NAM INDICATE THAT THERE
WILL BE LITTLE LOW-LEVEL MOISTURE AVAILABLE AHEAD OF THE FRONT WITH
CAA QUICKLY ENSUING AS LOWER LEVELS SATURATE. THUS...ANTICIPATE
A SHORT PERIOD OF MOSTLY RAIN ACROSS THE AREA EARLY TUESDAY WITH
850MB TEMPS WARMING TO 0-4C AND SUFFICIENT FOR MELTING. THE
EXCEPTION AT THE ONSET WILL BE ACROSS THE RIDGES AND NORTHEAST OF
PITTSBURGH WHERE A BRIEF PERIOD OF SLEET AND FREEZING RAIN WILL BE
POSSIBLE AND FZRA MAY LEAD TO BRIEFING ICING AT THE ONSET. PRECIP
WILL THEN QUICKLY TURN TO SNOW BY 18Z ACROSS THE AREA. GIVEN THE
PASSAGE OF THE FRONT AND 0.2-0.3 OF PRECIP WITH IT CROSSING DURING
THE DAY ADDS TO THE UNCERTAINTY OF HOW MUCH SNOW ACCUMULATION WILL
OCCUR. MOST OF THE ACCUMULATION HAS BEEN LIMITED TO NORTH AND EAST
OF PITTSBURGH AT THIS TIME. HIGHS ON TUESDAY WILL MOSTLY BE REACH
BEFORE 18Z...AROUND 5 DEGREES ABOVE NORMAL WITH MANY LOWLAND
LOCATIONS WARMING TO AROUND 40.
TUESDAY NIGHT INTO WEDNESDAY...BEHIND THE FRONT...LOW-LEVEL FLOW
WILL SHIFT TO WESTERLY ON TUESDAY NIGHT AND AID UPSLOPING FOR THE
RIDGES. THIS WILL CONTINUE INTO EARLY ON WEDNESDAY. WITH INITIAL
SNOW WITH FRONTAL PASSAGE THEN UPSLOPING...ANTICIPATE COMBINED
TUESDAY INTO WEDNESDAY TOTALS OF 3 TO 6 INCHES FOR THE RIDGES AND
2 TO 5 NORTH OF PITTSBURGH AT THIS TIME. WITH STRONG CAA BEHIND
THE FRONT...TEMPS WILL BE AROUND 10 DEGREES BELOW NORMAL FOR LOWS
TUESDAY NIGHT AND HIGHS ON WEDNESDAY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
SURFACE HIGH PRESSURE WILL BUILD ACROSS THE REGION WEDNESDAY NIGHT
WITH DRY CONDITIONS AND BELOW NORMAL TEMPERATURES INTO THURSDAY.
A DEEP TROUGH ACROSS THE WESTERN CONUS WILL CLOSE OFF INTO A LOW
ACROSS THE NORTHERN PLAINS THURSDAY NIGHT WITH AN OCCLUDING OR
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 /21Z SUNDAY THROUGH FRIDAY/...
GENERAL MVFR FORECAST INTO LATE AFTERNOON WITH BRIEF IFR IN SNOW
SHOWERS. BY THIS EVENING SURFACE RIDGE ADVANCING EAST FROM OHIO WILL
GRADUALLY END SNOW SHOWERS AND EVENTUALLY CLEAR OUT SKIES FOR THE
OVERNIGHT. WINDS GUSTING OVER 20KTS FROM THE NORTHWEST INTO THE
EVENING WILL SUBSIDE TO LIGHT AND VARIABLE BETWEEN 02-05Z. ON MONDAY
SURFACE HIGH WILL SLIDE EAST WITH VFR AND A SOUTH WIND TO 10 KTS
DEVELOPING MID TO LATE MORNING.
.OUTLOOK.../SUNDAY NIGHT THROUGH FRIDAY/...
A COLD FRONT WILL BRING RESTRICTIONS IN MIXED PRECIPITATION LATER
MONDAY NIGHT AND TUESDAY. EXPECT RESTRICTIONS TO LINGER IN COLD
NORTHWEST FLOW BEHIND FRONT THROUGH WEDNESDAY. VFR THURSDAY UNDER
HIGH PRESSURE. RESTRICTIONS POSSIBLE IN MIXED PRECIPITATION FOR
FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ074-
076.
WV...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR WVZ023-
041.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
SHORT TERM...WOODRUM
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
122 PM EST SUN FEB 17 2013
.SYNOPSIS...
SNOW SHOWERS WILL DECREASE IN COVERAGE THIS EVENING. HIGH PRESSURE
WILL THEN BUILD IN TONIGHT WITH DRY AND WARMER WEATHER ARRIVING
ON MONDAY. A COLD FRONT WILL THEN RETURN RAIN AND SNOW TO THE AREA
ON TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
18Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO ACCOUNT
FOR THE LATEST TRENDS IN RADAR AND SKY COVERAGE.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A MID-LEVEL TROUGH
AXIS CENTERED ACROSS EASTERN PA...LEAVING THE UPPER OHIO VALLEY IN
A NORTHWESTERLY FLOW IN THE WAKE OF THIS FEATURE. AT 850MB...A
NORTH-NORTHWESTERLY FLOW IS IN PLACE ACROSS THE LOWLANDS...WITH
MORE OF WESTERLY COMPONENT ACROSS THE LAUREL HIGHLANDS AND
ALLEGHENY FRONT OF WV/PA/MD. AT THE SURFACE...A LOW PRESSURE
SYSTEM IS OFF THE COAST OF NEW ENGLAND WITH A BROAD AREA OF HIGH
PRESSURE EXTENDING FROM THE UPPER MIDWEST TO THE GULF OF MEXICO.
THE COMBINATION OF WEAK VORT ENERGY SWINGING SOUTHEASTWARD ON THE
BACK END OF THE TROUGH ALONG WITH MOISTURE FILTERING IN FROM LAKE
HURON HAS ALLOWED SCATTERED SNOW SHOWERS TO CONTINUE ACROSS MUCH
OF THE AREA...WITH MORE WIDESPREAD SNOW SHOWERS WITH UPSLOPING
ACROSS THE RIDGES.
THIS AFTERNOON...THE UPPER TROUGH WILL PUSH OFF THE EAST COAST
WITH THE AREA REMAINING IN A NORTHWESTERLY FLOW AS HIGH PRESSURE
BEGINS TO BUILD IN FROM THE SOUTHWEST. VORT ENERGY SLIDING
EASTWARD WILL ALLOW FOR SNOW SHOWERS TO CONTINUE...BUT MOISTURE
WILL BECOME MORE SHALLOW WITH AN INVERSION LOWERING THIS
AFTERNOON...ALLOWING FOR SNOWFALL TO CONTINUE TO DECREASE IN
COVERAGE AND DIMINISH. UPSLOPING WILL ALLOW FOR ACCUMULATING
SNOWFALL TO CONTINUE IN THE EASTERN RIDGES...WITH AN ADDITIONAL 1
TO 2 INCHES THERE. WITH AMOUNTS ALREADY REPORTED AS HIGH AS 7
INCHES NEAR SEVEN SPRINGS...HAVE DECIDED TO MENTION ISOLATED 7 TO
10 STORM TOTAL AMOUNTS FOR THE HIGHEST ELEVATIONS...PARTICULARLY
OF WESTMORELAND AND FAYETTE COUNTIES.
TEMPS WILL ONLY INCREASE A FEW DEGREES TODAY...WITH HIGHS NEAR
LAMP GUIDANCE...RANGING FROM THE MID TEENS ACROSS THE EASTERN
RIDGES TO THE MID 20S SOUTH AND WEST OF PITTSBURGH. WITH A
TIGHTENED PRESSURE GRADIENT SETUP BETWEEN THE COASTAL LOW AND HIGH
APPROACHING FROM THE SOUTHWEST...WINDS OF 10 TO 15 MPH ARE
FORECAST WITH GUSTS TO 25 MPH FOR THE LOWLANDS AND 35 MPH FOR THE
RIDGES. THIS WILL LEAD TO WIND CHILLS BELOW 0 FOR THE RIDGES.
TONIGHT...HIGH PRESSURE WILL BUILD IN FROM THE SOUTHWEST WITH AN
850MB RIDGE MOVING INTO THE AREA AND BRINGING AN END TO LINGERING
UPSLOPING SNOWS FOR THE RIDGES. SKIES WILL CLEAR OUT WITH WINDS
DECREASING TO AROUND 5 MPH. WITH 850MB TEMPS AS COLD AS
16C...ALONG WITH CLEARING AND DECREASED WINDS CONTRIBUTING TO SOME
RADIATIONAL COOLING...LOWS TONIGHT WILL RANGE FROM THE SINGLE
DIGITS ACROSS THE HIGHER ELEVATIONS TO THE MID TEENS ACROSS THE
LOWLANDS.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
SOUTHERLY WINDS ON MONDAY ALONG WITH MOSTLY SUNNY SKIES WILL BRING A
MUCH WARMER DAY. COLD FRONT THAT WILL CROSS THE REGION MONDAY NIGHT
AND TUESDAY APPEARS TO BE MOVING SLIGHTLY SLOWER...AND HAVE DELAYED
FRONTAL PASSAGE BY A FEW HOURS. NO CHANGE TO CATEGORICAL POPS IN THE
FORECAST. HAVE REMOVED MENTION OF FREEZING PRECIPITATION WITH MODELS
NOT SHOWING MUCH OF A WARM TONGUE ALOFT. HOWEVER...WITH LOWS MONDAY
NIGHT EXPECTED TO BE IN THE MID 30S...TEMPERATURES WILL BE MARGINAL
FOR SNOW. A CHANGE IN THE TEMPERATURE FORECAST BY JUST A COUPLE OF
DEGREES COULD HAVE SIGNIFICANT IMPACTS TO THE PRECIPITATION TYPE
FORECAST AND POSSIBLE SNOWFALL ACCUMULATION. WITH THIS FORECAST
UPDATE...HAVE ADDED SOME LIGHT SNOW ACCUMULATIONS...GENERALLY NORTH
OF PITTSBURGH. NEARLY ALL LOCATIONS WILL SEE AT LEAST SOME RAIN ON
TUESDAY MORNING...WITH PRECIPITATION CHANGING OVER TO SNOW DURING
THE AFTERNOON HOURS BEHIND THE COLD FRONT.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AN ECMWF/GFS/CANADIAN BLEND INDICATES A CLOSED UPPER LEVEL VORTEX
CENTERED ACROSS THE NORTHERN GREAT LAKES WITH THE COLD FRONT
SHIFTING EAST OF THE AREA TUESDAY NIGHT. LINGERING SNOW SHOWERS ON
THE BACK SIDE OF THE FRONT WILL BE MOSTLY DIMINISHING TUESDAY
NIGHT. THE CHC OF SNOW SHOWERS WILL LINGER INTO WEDNESDAY FOR THE
HIGHER ELEVATIONS WITH UPSLOPING FAVORED BY A WESTERLY FLOW
VEERING TO WEST-NWRLY.
A GFSE/NAEFS MODEL CONSENSUS INDICATES A MID-LEVEL RIDGE AND SURFACE
HIGH SHIFTING PUSHING INTO THE UPPER OHIO VALLEY WEDNESDAY NIGHT
INTO THURSDAY WITH A DRY FORECAST IN PLACE.
A DEEP TROUGH ACROSS THE WESTERN CONUS WILL CLOSE OFF INTO A LOW
ACROSS THE NORTHERN PLAINS THURSDAY NIGHT. THE LOW WILL SWING A
FRONTAL BOUNDARY NORTHEASTWARD INTO THE UPPER OHIO VALLEY THROUGH
THE DAY FRIDAY. GFS/ECMWF ARE INDICATING THE 1000-850MB 1300M
THICKNESS LINE SLIPPING NORTHWARD ACROSS WESTERN PA ON FRIDAY. WITH
A WARMER WEDGE OF AIR ADVECTING INTO THE AREA AND CREATING A
MELTING LAYER ALOFT...THERE IS THE POTENTIAL FOR A WINTRY MIX EVENT
ACROSS THE AREA EARLY ON FRIDAY. GIVEN THAT THIS IS A DAY 6
FORECAST...THERE IS STILL QUITE A BIT OF UNCERTAINTY WITH HOW THE
THERMAL PROFILE AND AVAILABLE MOISTURE WILL SETUP WITH THIS
EVENT...SO HAVE GONE WITH A MIX OF RAIN AND SNOW AT THIS TIME.
HOWEVER...MODEL SOUNDINGS ARE HINTING AT THE POTENTIAL FOR
SLEET/FZRA AT THE ONSET OF PRECIP. THUS...THIS POTENTIAL EVENT WILL
NEED TO BE MONITORED IN THE COMING DAYS.
MODELS DIVERGE FRIDAY NIGHT INTO SATURDAY AND THUS DO NOT WAVER FAR
FROM HPC FORECAST WITH SCHC POPS FOR THE END OF THE FORECAST PERIOD.
TEMPS WILL BE AROUND 10 DEGREES BELOW NORMAL BEHIND THE FRONT ON
WEDNESDAY AND THEN MODERATE EACH DAY TO NEAR NORMAL SEASONAL VALUES
FRIDAY INTO SATURDAY.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
GENERAL MVFR FORECAST INTO MID AFTERNOON WITH BRIEF IFR IN SNOW
SHOWERS. BY THIS EVENING SURFACE RIDGE WILL BRING AN END TO SNOW
SHOWERS AND GRADUALLY CLEAR OUT SKIES FOR THE OVERNIGHT. WINDS
GUSTING OVER 20KTS FROM THE NORTHWEST INTO THE EVENING WILL SUBSIDE
TO LIGHT AND VARIABLE BETWEEN 02-05Z. ON MONDAY SURFACE HIGH WILL
SLIDE EAST WITH VFR AND A SOUTH WIND TO 10 KTS DEVELOPING MID
MORNING.
.OUTLOOK.../SUNDAY NIGHT THROUGH FRIDAY/...
A COLD FRONT WILL BRING RESTRICTIONS IN RAIN OR SNOW LATER MONDAY
NIGHT AND TUESDAY. EXPECT RESTRICTIONS LINGER IN COLD NWRLY FLOW
BEHIND FRONT THROUGH WEDNESDAY. VFR THURSDAY UNDER HIGH PRESSURE.
RESTRICTIONS POSSIBLE IN MIXED PRECIPITATION FOR FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
PAZ074-076.
WV...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
WVZ023-041.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1031 AM EST SUN FEB 17 2013
.SYNOPSIS...
SNOW SHOWERS WILL DECREASE IN COVERAGE TODAY. HIGH PRESSURE WILL
THEN BUILD IN TONIGHT WITH DRY AND WARMER WEATHER ARRIVING ON
MONDAY. A COLD FRONT WILL THEN RETURN RAIN AND SNOW TO THE AREA ON
TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
15Z ENHANCED SHORT TERM FORECAST HAS BEEN ISSUED THIS MORNING TO
UPDATE THE WINTER WEATHER HEADLINES...EXPANDING THE ADVISORY FOR
THE RIDGES UNTIL 21Z...AND ADDING THE MENTION OF STORM TOTAL
AMOUNTS.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A MID-LEVEL TROUGH
AXIS CENTERED ACROSS EASTERN PA...LEAVING THE UPPER OHIO VALLEY IN
A NORTHWESTERLY FLOW IN THE WAKE OF THIS FEATURE. AT 850MB...A
NORTH-NORTHWESTERLY FLOW IS IN PLACE ACROSS THE LOWLANDS...WITH
MORE OF WESTERLY COMPONENT ACROSS THE LAUREL HIGHLANDS AND
ALLEGHENY FRONT OF WV/PA/MD. AT THE SURFACE...A LOW PRESSURE
SYSTEM IS OFF THE COAST OF NEW ENGLAND WITH A BROAD AREA OF HIGH
PRESSURE EXTENDING FROM THE UPPER MIDWEST TO THE GULF OF MEXICO.
THE COMBINATION OF WEAK VORT ENERGY SWINGING SOUTHEASTWARD ON THE
BACK END OF THE TROUGH ALONG WITH MOISTURE FILTERING IN FROM LAKE
HURON HAS ALLOWED SCATTERED SNOW SHOWERS TO CONTINUE ACROSS MUCH
OF THE AREA...WITH MORE WIDESPREAD SNOW SHOWERS WITH UPSLOPING
ACROSS THE RIDGES.
THIS AFTERNOON...THE UPPER TROUGH WILL PUSH OFF THE EAST COAST
WITH THE AREA REMAINING IN A NORTHWESTERLY FLOW AS HIGH PRESSURE
BEGINS TO BUILD IN FROM THE SOUTHWEST. VORT ENERGY SLIDING
EASTWARD WILL ALLOW FOR SNOW SHOWERS TO CONTINUE...BUT MOISTURE
WILL BECOME MORE SHALLOW WITH AN INVERSION LOWERING THIS
AFTERNOON...ALLOWING FOR SNOWFALL TO CONTINUE TO DECREASE IN
COVERAGE AND DIMINISH. UPSLOPING WILL ALLOW FOR ACCUMULATING
SNOWFALL TO CONTINUE IN THE EASTERN RIDGES...WITH AN ADDITIONAL 1
TO 3 INCHES THERE. WITH AMOUNTS ALREADY REPORTED AS HIGH AS 7
INCHES NEAR SEVEN SPRINGS...HAVE DECIDED TO MENTION ISOLATED 7 TO
10 STORM TOTAL AMOUNTS FOR THE HIGHEST ELEVATIONS...PARTICULARLY
OF WESTMORELAND AND FAYETTE COUNTIES.
TEMPS WILL ONLY INCREASE A FEW DEGREES TODAY...WITH HIGHS NEAR
LAMP GUIDANCE...RANGING FROM THE MID TEENS ACROSS THE EASTERN
RIDGES TO THE MID 20S SOUTH AND WEST OF PITTSBURGH. WITH A
TIGHTENED PRESSURE GRADIENT SETUP BETWEEN THE COASTAL LOW AND HIGH
APPROACHING FROM THE SOUTHWEST...WINDS OF 10 TO 15 MPH ARE
FORECAST WITH GUSTS TO 25 MPH FOR THE LOWLANDS AND 35 MPH FOR THE
RIDGES. THIS WILL LEAD TO WIND CHILLS BELOW 0 FOR THE RIDGES.
TONIGHT...HIGH PRESSURE WILL BUILD IN FROM THE SOUTHWEST WITH AN
850MB RIDGE MOVING INTO THE AREA AND BRINGING AN END TO LINGERING
UPSLOPING SNOWS FOR THE RIDGES. SKIES WILL CLEAR OUT WITH WINDS
DECREASING TO AROUND 5 MPH. WITH 850MB TEMPS AS COLD AS
16C...ALONG WITH CLEARING AND DECREASED WINDS CONTRIBUTING TO SOME
RADIATIONAL COOLING...LOWS TONIGHT WILL RANGE FROM THE SINGLE
DIGITS ACROSS THE HIGHER ELEVATIONS TO THE MID TEENS ACROSS THE
LOWLANDS.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
SOUTHERLY WINDS ON MONDAY ALONG WITH MOSTLY SUNNY SKIES WILL BRING A
MUCH WARMER DAY. COLD FRONT THAT WILL CROSS THE REGION MONDAY NIGHT
AND TUESDAY APPEARS TO BE MOVING SLIGHTLY SLOWER...AND HAVE DELAYED
FRONTAL PASSAGE BY A FEW HOURS. NO CHANGE TO CATEGORICAL POPS IN THE
FORECAST. HAVE REMOVED MENTION OF FREEZING PRECIPITATION WITH MODELS
NOT SHOWING MUCH OF A WARM TONGUE ALOFT. HOWEVER...WITH LOWS MONDAY
NIGHT EXPECTED TO BE IN THE MID 30S...TEMPERATURES WILL BE MARGINAL
FOR SNOW. A CHANGE IN THE TEMPERATURE FORECAST BY JUST A COUPLE OF
DEGREES COULD HAVE SIGNIFICANT IMPACTS TO THE PRECIPITATION TYPE
FORECAST AND POSSIBLE SNOWFALL ACCUMULATION. WITH THIS FORECAST
UPDATE...HAVE ADDED SOME LIGHT SNOW ACCUMULATIONS...GENERALLY NORTH
OF PITTSBURGH. NEARLY ALL LOCATIONS WILL SEE AT LEAST SOME RAIN ON
TUESDAY MORNING...WITH PRECIPITATION CHANGING OVER TO SNOW DURING
THE AFTERNOON HOURS BEHIND THE COLD FRONT.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AN ECMWF/GFS/CANADIAN BLEND INDICATES A CLOSED UPPER LEVEL VORTEX
CENTERED ACROSS THE NORTHERN GREAT LAKES WITH THE COLD FRONT
SHIFTING EAST OF THE AREA TUESDAY NIGHT. LINGERING SNOW SHOWERS ON
THE BACK SIDE OF THE FRONT WILL BE MOSTLY DIMINISHING TUESDAY
NIGHT. THE CHC OF SNOW SHOWERS WILL LINGER INTO WEDNESDAY FOR THE
HIGHER ELEVATIONS WITH UPSLOPING FAVORED BY A WESTERLY FLOW
VEERING TO WEST-NWRLY.
A GFSE/NAEFS MODEL CONSENSUS INDICATES A MID-LEVEL RIDGE AND SURFACE
HIGH SHIFTING PUSHING INTO THE UPPER OHIO VALLEY WEDNESDAY NIGHT
INTO THURSDAY WITH A DRY FORECAST IN PLACE.
A DEEP TROUGH ACROSS THE WESTERN CONUS WILL CLOSE OFF INTO A LOW
ACROSS THE NORTHERN PLAINS THURSDAY NIGHT. THE LOW WILL SWING A
FRONTAL BOUNDARY NORTHEASTWARD INTO THE UPPER OHIO VALLEY THROUGH
THE DAY FRIDAY. GFS/ECMWF ARE INDICATING THE 1000-850MB 1300M
THICKNESS LINE SLIPPING NORTHWARD ACROSS WESTERN PA ON FRIDAY. WITH
A WARMER WEDGE OF AIR ADVECTING INTO THE AREA AND CREATING A
MELTING LAYER ALOFT...THERE IS THE POTENTIAL FOR A WINTRY MIX EVENT
ACROSS THE AREA EARLY ON FRIDAY. GIVEN THAT THIS IS A DAY 6
FORECAST...THERE IS STILL QUITE A BIT OF UNCERTAINTY WITH HOW THE
THERMAL PROFILE AND AVAILABLE MOISTURE WILL SETUP WITH THIS
EVENT...SO HAVE GONE WITH A MIX OF RAIN AND SNOW AT THIS TIME.
HOWEVER...MODEL SOUNDINGS ARE HINTING AT THE POTENTIAL FOR
SLEET/FZRA AT THE ONSET OF PRECIP. THUS...THIS POTENTIAL EVENT WILL
NEED TO BE MONITORED IN THE COMING DAYS.
MODELS DIVERGE FRIDAY NIGHT INTO SATURDAY AND THUS DO NOT WAVER FAR
FROM HPC FORECAST WITH SCHC POPS FOR THE END OF THE FORECAST PERIOD.
TEMPS WILL BE AROUND 10 DEGREES BELOW NORMAL BEHIND THE FRONT ON
WEDNESDAY AND THEN MODERATE EACH DAY TO NEAR NORMAL SEASONAL VALUES
FRIDAY INTO SATURDAY.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
GENERAL MVFR FORECAST FOR REMAINDER OF MORNING WITH ISOLATED IFR AT
TIMES IN ANY HEAVIER SQUALL. SNOW SHOWERS AND SNOW BANDS WILL BEGIN
TO DIMINISH BY 17Z AND END DURING THE AFTERNOON WITH IFR RETURNING
WEST TO EAST ACROSS TERMINALS.
COASTAL LOW MOVING OFF OF NEW ENGLAND WILL TIGHTEN THE SFC PRESSURE
GRADIENT WILL PROVIDE GUSTY WINDS THIS AFTERNOON.
.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
HI PRES/VFR EXPD SUN NT AND MON. A CDFNT IS EXPD TO BRING
RESTRICTIONS TUE...WITH RESTRICTIONS LINGERING IN COLD NWRLY FLOW
AFT FROPA THRU WED. HI PRES/VFR EXPD FOR THU.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
PAZ074-076.
WV...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
WVZ023-041.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
401 AM EST SUN FEB 17 2013
.SYNOPSIS...
AN UPPER TROUGH PASSES THROUGH THE REGION THIS MORNING. LOW
PRESSURE WILL RAPIDLY INTENSIFY TODAY AS IT MOVES NORTHEASTWARD.
HIGH PRESSURE BUILDS IN THIS AFTERNOON THROUGH MONDAY BEFORE A
COLD FRONT MOVES THROUGH TUESDAY. HIGH PRESSURE RETURNS WEDNESDAY.
A WAVE OF LOW PRESSURE MAY IMPACT THE MID-ATLANTIC REGION LATE IN
THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AN AREA OF LOPRES IS CURRENTLY LOCATED OFF THE NRN MID-ATLANTIC
COAST ERY THIS MRNG. AS THE COASTAL LOW DEEPENS RAPIDLY AND
TRACKS NEWD TO OFF THE NEW ENGLAND COAST TDA...THE PRESSURE
GRADIENT WILL STRENGTHEN ON THE BACKSIDE OF THE LOW. A BRISK NW
WIND GUSTING 20-30 MPH THIS MRNG WILL INCREASE TO 40 MPH THIS
AFTN.
MEANWHILE...A NEGATIVELY-TILTED TROUGH ASSOCIATED WITH AN UPPER LOW
OVER SRN QUEBEC-ONTARIO WILL PROGRESS THRU THE AREA THIS MRNG.
DPVA AHEAD OF THE UPPER TROUGH HAS PROVIDED LIFT FOR LAKE-EFFECT
SNOW SHOWERS TO MOVE SEWD FROM LAKE ERIE TO THE ALLEGHENY FRONT.
WINTER WX ADVISORY REMAINS IN EFFECT TDA FOR THE WRN SLOPES OF THE
ALLEGHENY FRONT...WHERE SNOWFALL ACCUMULATIONS OF 2-4 INCHES ARE
EXPECTED. COMBINED WITH THE GUSTY NW WINDS...TEMPORARY VSBYS OF A
QUARTER MILE OR LESS ARE POSSIBLE IN HEAVIER SNOW SHOWERS.
TYPICALLY SNOW SHOWER ACTIVITY DISSIPATES AS IT MOVES EAST OF THE
ALLEGHENY FRONT...BUT CAA WILL PROVIDE AN ENVIRONMENT CONDUCIVE FOR
CONTINUATION OF ISO TO SCT SNOW SHOWERS FARTHER DOWNSTREAM. 00Z
NAM/GFS AND LATEST RAP BUFKIT PROFILES INDICATE STEEP LAPSE RATES
BELOW H7 TDA WITH LIMITED CONVECTIVE INSTABILITY WITHIN DENDRITIC
GROWTH ZONE. THERMAL PROFILES WILL BE FAVORABLE FOR DOWNWARD
TRANSPORT OF GUSTY WINDS ALOFT IN THESE SNOW SHOWERS. ACCORDINGLY...
THERE IS A POTENTIAL FOR LOCALLY/BRIEF HEAVIER SNOW SHOWERS OR
SQUALLS THAT COULD DROPPRODUCE A QUICK LGT ACCUMULATION...LOW
VSBYS AND GUSTY WINDS. IN WAKE OF THE UPPER TROUGH PASSAGE...
EXPECT A DOWNWARD TREND IN SNOW SHOWER ACTIVITY THRUOUT THE AFTN.
ANY ISO SNOW SHOWERS THIS AFTN THOUGH WILL HAVE THE POTENTIAL TO
MIX DOWN 35-45 MPH GUSTS.
LLVL JET MOVES THRU THIS EVE. OPTED TO NOT ISSUE A WIND ADVISORY
FOR THE HIGHER RIDGES AND IN NRN MD. ALTHOUGH WINDS JUST ABOVE THE
SFC WILL BE CLOSE TO 40 KT...CAA CEASES AND LAPSE RATES BEGIN TO
WEAKEN.
WITH CAA REGIME...USED A BLEND OF BIAS-CORRECTED MAV/MET GUIDANCE
FOR MAX/MIN TEMPS...WHICH WERE ON THE COLDER SIDE TDA AND WARMER
SIDE TNGT. TEMPS THIS AFTN WILL STRUGGLE TO REACH THE FREEZING
MARK NORTH AND WEST OF THE CITIES. MIN TEMPS IN THE TEENS AND 20S
TNGT...EXCEPT SINGLE DIGITS ALONG THE RIDGES. WIND CHILLS MAY DROP
BELOW ZERO IN THE WRN POTOMAC HIGHLANDS...BUT CONFIDENCE NOT HIGH
ENOUGH ATTM TO ISSUE A SECOND PERIOD WIND CHILL ADVISORY.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AN ACTIVE PATTERN TO SAY THE LEAST...AS WE GO INTO AN ALMOST
EVERY-OTHER-DAY WX SYSTEM FOR THE COMING WEEK - IF NOT LONGER.
MONDAY WILL BE THE REPRIEVE FROM THIS WEEKEND`S SYSTEM. PART OF THE
ERN SECTION OF THE CWA WILL STILL BE ON THE TAIL-END OF THE EXITING
SYSTEM...KEEPING TEMPS A FEW DEGREES LOWER MON AFTN THAN THE
SHENANDOAH VLY. ALL AREAS WILL APPROACH 40 DEG BY MID AFTN...THOUGH
WEAK DOWNSLOPING ACROSS THE WRN MTNS/VLYS WILL HELP WARM TEMPS UP A
FEW MORE DEGREES...POSSIBLY REACHING THE M-U40S IN PLACES ALONG AND
E OF I-81.
SKIES WILL CLEAR OUT OTHER THAN SOME PASSING CIRRUS/MID LEVEL
STRATUS - THE TAIL END OF A WARM FRONT THAT WILL PASS WELL TO OUR
NORTH. THE FRONT WILL BE THE PRECURSOR TO THE NEXT SYSTEM THAT WILL
QUICKLY DEVELOP E OF THE MS RVR...REACH PEAK INTENSITY JUST TO OUR
WEST OVER THE OHIO RVR VLY AND DISSIPATE AS IT MOVES ACROSS THE ERN
SEABOARD.
DESPITE LOSING MUCH OF ITS MOISTURE OVER THE UPPER MIDWEST BEFORE
EVEN CROSSING THE MTNS...WHAT PRECIP DOES MOVE ACROSS THE AREA WILL
START OFF AS A WINTRY MIX ACROSS MUCH OF THE AREA TO START THE DAY
ON TUE. ENOUGH LOW LEVEL SUBFREEZING AIR WILL BE IN PLACE NEAR THE
SFC...WHILE A WARM NOSE ALOFT IN THE BOUNDARY LAYER (FROM A STRONG
LOW LEVEL JET MAX) WILL BE AT LEAST A COUPLE/FEW DEGREES ABOVE
FREEZING. THE NAM DEPICTS A GOOD COMPACT LOW LEVEL JET MAX...W/ THE
GFS SHOWING MORE OF A BROAD COLUMN OF STRONGER WINDS...WHICH IS
LIKELY A BIT TOO STRONG.
A MIX OF RAIN/SLEET/FREEZING RAIN POSSIBLE FROM ONSET - PREDAWN HRS
THRU MID-LATE MRNG. MORE OF A SNOW/WINTRY MIX FOR THE WRN ZONES AND
HIGHER TERRAIN. PRECIP WILL BECOME ALL-RAIN OUTSIDE THE MTNS FOR THE
EARLY-MID AFTN HRS...STILL ONLY LIGHT QPF...UNTIL THE INCOMING COLD
FRONT MOVES THIS ACTIVITY EAST OF THE AREA BY LATE AFTN/EARLY EVE.
MOST GUIDANCE MEMBERS IN GOOD AGREEMENT ON TIMING/QPF ASSOCIATED W/
SYSTEM BUT WENT W/ MORE OF A MET BLEND - SLIGHTLY LOWER TEMPS - AND
MORE CLOUD COVER LINGERING INTO THE LATE AFTN BEHIND THE FRONTAL
PASSAGE.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
WE`LL HAVE A COUPLE OF DAYS BEFORE THE NEXT SYSTEM ARRIVES - WED
AND THU. THE DEEP PARENT UPPER LOW RESPONSIBLE FOR THE TUE SYSTEM
WILL SWING BY TO OUR NORTH ON WED...KEEPING TEMPS BELOW AVG EACH
DAY. EVEN ON THU...THE BEFORE FRONTAL HIGH PRESSURE RIDGE WON`T BE
ABLE TO BUILD IN STRONG ENOUGH TO BRING MORE MILD TEMPS TO THE
AREA. EACH DAY WILL HOWEVER BE DRY AND MOSTLY CLEAR...THOUGH THE
NEXT LOW PRESSURE SYSTEM WILL BE ON THE DOORSTEP THU NIGHT.
GFS/EURO IS GOOD AGREEMENT THIS FAR OUT THAT THE NEXT LOW PRESSURE
SYSTEM WILL DEVELOP OVER THE CNTRL PLAINS MID WEEK...W/ THE SYSTEM
BASICALLY SPLITTING IN HALF AS IT MOVES EWD. THE SRN BRANCH WILL
THEN BE PICKED UP AND MOVE TOWARD THE AREA INTO THE COMING
WEEKEND...W/ ANOTHER POSSIBLE WINTRY MIX FRI AND SAT.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
PREDOMINANTLY VFR CONDITIONS TDA. MAIN WX CONCERN WILL BE THE GUSTY
NW WINDS AND SHSN. COVERAGE OF SHSN WILL BE LOW TDA...SO UNCERTAINTY
IN TIMING OF THIS ACTIVITY AT A SPECIFIC TERMINAL IS VERY HIGH.
THERE IS A POTENTIAL FOR SOME OF THESE SHSN TO BRIEFLY PRODUCE LOW
VSBYS AND GUSTY WINDS /25-30 KT THIS MRNG AND 30-40 KT THIS AFTN/.
MORE DETAIL WE NEED TO BE ADDED TO SUBSEQUENT TAFS AS WE MONITOR
THIS ACTIVITY ON RADAR.
VFR CONDITIONS TNGT. BREEZY NW WINDS CONTINUE THIS EVE WITH GUSTS TO
35 KT POSSIBLE. WINDS WEAKEN OVNGT.
HIGH PRESSURE MONDAY...WEST WINDS 10-15KT AND MOSTLY CLEAR SKIES.
A COLD FRONT WILL QUICKLY SLIDE OVER THE AREA TUE AFTN...BRINGING
SOME WINTRY MIX OUT AHEAD OF IT...CHANGING TO RAIN BY AFTN AND
MOVING OFF THE COAST TUE EVE. WED-THU MORE HIGH PRESSURE...THEN AN
ACTIVE END TO THE WEEK AS A FRONTAL BOUNDARY SIMILAR TO TUESDAY`S
PASSAGE BRINGS MORE WINTRY PRECIP ON FRI.
&&
.MARINE...
A GALE WRNG HAS BEEN ISSUED FOR ALL MARINE ZONES TDA AND TNGT...WITH
GALES LIKELY OCCURRING DURING THE AFTN AND EVE /BUT MAY CONTINUE A
FEW HRS OVNGT IN THE CHSPK BAY/. ISO SNOW SHOWERS WILL PRODUCE
LOCALLY HIGHER GUSTS AND BRIEF REDUCTIONS IN VSBYS FROM MID MRNG
THRU ERY AFTN.
SCA CONDITIONS WILL REAPPEAR ON MON NIGHT...AFTER A RELATIVELY
QUIET DAY OF HIGH PRES. A WEAK COLD FRONT WILL MOVE THRU W/ LIGHT
PRECIP ON TUE...THOUGH WINDS WILL PICK UP AGAIN WELL INTO SCA
RANGE TUE INTO WED. HIGH PRESSURE FOR THE BACK HALF OF THE
WEEK...AHEAD OF ANOTHER LOW PRESSURE SYSTEM FOR THE END OF THE WEEK.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
MDZ501.
VA...NONE.
WV...WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
WVZ501-503-505.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
ANZ530>543.
GALE WARNING UNTIL 6 AM EST MONDAY FOR ANZ530>543.
&&
$$
KLEIN/GMS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1241 PM EST SUN FEB 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 514 AM EST SUN FEB 17 2013
WV IMAGERY AND RUC ANALYSIS INDICATED NNW MID/UPPER LEVEL FLOW
THROUGH THE WRN GREAT LAKES BETWEEN A TROUGH INTO THE ERN LAKES AND
A RIDGE OVER THE NRN PLAINS INTO MANITOBA. UPSTREAM ANOTHER THROUGH
AND VIGOROUS SHRTWV WAS MOVING THROUGH THE NRN ROCKIES. AT THE
SFC...A RIDGE EXTENDED FROM W OF JAMES BAY INTO UPPER MI AND WI.
WITH VERY LIGHT SYNOPTIC SCALE WINDS...LAKE INDUCED TROUGHING AND
WIND FIELDS DOMINATED LAKE SUPERIOR. LAND BREEZES ALONG WITH A WEAK
NRLY GRADIENT FLOW HAS RESULTING IN STRONGEST AREA OF LOW LEVEL CONV
OVER E CNTRL LAKE SUPERIOR FOCUSING LES INTO THE PICTURED ROCKS AND
FAR NRN SCHOOLCRAFT COUNTY. HOWEVER...SNOW INTENSITY HAS
DIMINISHED...PER RADAR REFLECTIVITY TRENDS. UPSTREAM...CLOUDS WERE
THICKENING ACROSS MN WITH WAA PATTERN AHEAD OF A TROUGH FROM SRN
SASK INTO ERN MT.
AS THE HIGH SHIFTS TO THE EAST...WINDS OVER ERN LAKE SUPERIOR WILL
FINALLY BECOME SRLY...PUSHING ANY REMAINING LES OFFSHORE. ADDITIONAL
ACCUMULATIONS AROUND AN INCH MAY BE POSSIBLE NEAR THE SHORE FROM
PICTURED ROCKS TO GRAND MARAIS. WAA WITH INCREASING SRLY WINDS AND
SUNSHINE DURING MUCH OF THE DAY WILL HELP TEMPS RECOVER QUICKLY FROM
THE FRIGID START WITH MAX READINGS CLOSER TO SEASONAL
AVERAGES...FROM AROUND 20 CNTRL TO 25 WEST.
NAM/GFS 280K-295K ISENTROPIC PROGS AND SATELLITE TRENDS SUGGEST THAT
CLOUDS WILL MOVE IN LATE TODAY AND THICKEN ACROSS THE AREA THIS
EVENING. THE STRONGEST ASCENT AND BEST CHANCE TO SATURATE THE LOWER
LEVELS IN THE VERY DRY ANTECEDENT AIRMASS WILL BE ACROSS LAKE
SUPERIOR AND THE TIP OF THE KEWEENAW. TO THE SOUTH...A LARGE PORTION
OF ANY PCPN MAY EVAPORATE BEFORE REACHING THE SFC. SO...A QPF
PATTERN MORE IN LINE WITH THE NAM WAS FAVORED. ONLY CHANCE POPS WERE
INCLUDED WITH MINIMAL IF ANY SNOW ACCUMULATIONS LESS THAN A HALF
INCH.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 514 AM EST SUN FEB 17 2013
ACTIVE WINTER PATTERN CONTINUES THROUGH THE UPCOMING WEEK. A COUPLE
SHOTS AT WIDESPREAD SYNOPTIC SNOWFALL...FIRST ON MONDAY/MONDAY NIGHT
THEN AGAIN ON FRIDAY. BETWEEN THESE SYSTEMS...ROBUST NNW-NW FLOW
LAKE EFFECT EVENT AFFECTS NORTHERN HALF OF UPR MICHIGAN TUESDAY INTO
WEDNESDAY. AFTER ABOVE NORMAL TEMPERATURES ON MONDAY IN SOUTHERLY
FLOW AHEAD OF LOW PRESSURE...TEMPERATURES MOST OF THE WEEK WILL BE
AT OR BLO NORMAL. COLDEST TIME APPEARS TO BE TUESDAY INTO WEDNESDAY.
TEMPERATURES REBOUND TO AROUND NORMAL TO CLOSE THE WEEK.
FIRST ISSUE IS LGT SNOW ON MONDAY AS UPR TROUGH AND DEEPENING
SFC-H85 LOWS MOVE TOWARD UPR LAKES FROM SCNTRL CANADA. WARM AIR
ADVECTION BATCH OF LGT SNOW SHOULD BE ONGOING TO START THE DAY
ACROSS LAKE SUPERIOR AND FAR NORTHERN CWA. INDICATIONS ARE THAT MOST
OF THIS SNOW WILL BE DIMINISHING THROUGH THE MORNING...LEAVING A
LULL OVER MUCH OF CWA UNTIL THE AFTN. AFT 18Z...SOUNDINGS INDICATE
DEEP MOISTENING FROM ABOVE H8 AS SFC-H85 LOWS DEEPEN WHILE MOVING
INTO WESTERN HALF OF UPR MICHIGAN. AT THIS POINT IS WHERE MODELS
DIVERGE IN HANDLING TRACK OF SFC LOW. GFS/ECMWF STAYING CONSISTENT
WITH SFC LOW MOVING INTO SOUTH CNTRL UPR MICHIGAN BY 00Z TUESDAY AND
MOVING JUST EAST OF UPR MICHIGAN BY 12Z TUESDAY. GEM-NH/UKMET SLOWER
AND FARTHER WEST WITH THE SFC LOW AS THEY SHOW IT OVER NORTHERN LK
MICHIGAN/STRAITS BY 12Z TUESDAY. ONLY A SUBTLE DIFFERENCE BUT IT IS
RESULT OF DEEPER/CLOSED OFF UPR TROUGH. A DEEPER SYSTEM WOULD RESULT
IN LGT-MODERATE SYNOPTIC SNOW OVER EAST HALF OF CWA THROUGH MOST OF
MONDAY NIGHT COMPARED TO GFS/ECMWF. MORE MOISTURE IS ALSO BROUGHT
INTO SYSTEM MONDAY AFTN/EVENING...SO ULTIMATELY SNOW AMOUNTS WOULD
BE CLOSE TO ADVY LEVELS. NOT GOING THAT WAY NOW...THOUGH WILL ADMIT
THE GEM-NH CONSISTENCY IS A BIT CONCERNING. EVEN SO...PRIMARY
WEST-EAST JET ENERGY STAYS LOCKED INTO SOUTHERN STREAM OF THE UPPER
TROUGH WHICH SUPPORTS GOING WITH MORE PROGRESSIVE UPR TROUGH AND A
FARTHER EAST SFC LOW TRACK. UPSHOT...A FEW INCHES OF SNOW IN THE
EAST WITH JUST AN INCH OR TWO ELSEWHERE OVR CWA. SNOW WILL BE A
WETTER TYPE SNOW...NOT THE REALLY FLUFFY VARIETY THAT HAS BEEN WITH
US LATELY.
DEEPENING UPPER TROUGH SWINGS ACROSS GREAT LAKES ON TUESDAY HELPING
TO DRAW IN MUCH COLDER AIR YET AGAIN. H85 TEMPS AT 06Z TUESDAY ONLY
AS COLD AS AROUND -13C OVR LK SUPERIOR BUT BY 18Z TUESDAY ARE
ALREADY DOWN BLO -20C. ALL THE WHILE...SINCE UPR TROUGH IS DEEPENING
OVR THE AREA...THERE IS PLENTY OF DEEPER MOISTURE PRESENT WITH
STRONG CYCLONIC N-NW FLOW. KIND OF A PSUEDO LAKE ENHANCED SETUP
THOUGH THERE DOES NOT LOOK TO BE MUCH LARGE SCALE LIFT GOING ON.
SLR/S IN THEORY SHOULD END UP OVR 30:1 BUT GIVEN STRONG WINDS OVR 30
KTS IN THE BLYR...EXPECT FRACTURING TO HOLD SLR/S DOWN TO AN AVERAGE
OF 25-30:1. FIRST PASS AT SNOW AMOUNTS INDICATES HIGH-END ADVY BUT
SIMILAR TO LAST EVENT...LONG DURATION OF THE SNOW MAY RESULT IN SNOW
TOTALS FROM LATE MONDAY NIGHT THROUGH TUESDAY NIGHT AND WEDNESDAY
OVER A FOOT IN SOME LOCATIONS. FAVORED LOCATIONS WITH EXPECTED NNW
WINDS WOULD BE MUCH OF HIGHER TERRAIN OF ONTONAGON COUNTY THROUGH
TWIN LAKES...HIGHER TERRAIN OF BARAGA AND NORTHERN MARQUETTE
COUNTY...THEN EVENTUALLY THE SNOWBELTS OVER OF THE EASTERN CWA LATER
TUESDAY THROUGH WEDNESDAY. UNLIKE RECENT LAKE SNOW EVENT...WIND/BLSN
WILL BE BIGGER ISSUE WITH WELL MIXED BLYR. EXPECT WIDESPREAD BLSN
AND REDUCED VSBY ALONG WITH MODERATE TO HEAVY SNOW SHOWERS.
SINCE WE STILL HAVE TO GET THROUGH THE WIDESPREAD SYNOPTIC LGT SNOW
MONDAY AND MONDAY EVENING AND THIS IS MAINLY A 5TH PERIOD AND BEYOND
EVENT DID NOT ISSUE ANY HEADLINES AT THIS POINT. WILL MENTION IN HWO
AND HIT UP THE BLSN AS WELL. SEEMS THAT TRAVEL MAY BE DIFFICULT NEAR
MUCH OF LK SUPERIOR TUESDAY INTO TUESDAY EVENING.
REST OF LONG TERM...LK EFFECT DIMINISHES STEADILY ON WEDNESDAY FROM
WEST TO EAST AS UPR TROUGH/DEEPER MOISTURE EXITS TO EAST. LEFT OVER
LAKE EFFECT WILL BE PLAGUED BY LOWERING INVERSION AND DIMINISHING
CYCLONIC FLOW. WEAKER LK EFFECT AND/OR FLURRIES HANG ON THROUGH
THURSDAY OVER NCNTRL CWA WITH WINDS BECOMING N/NE. DRY ELSEWHERE AS
WE AWAIT SYSTEM THAT WILL BE BRINGING SNOW TO PARTS OF NORTHERN
PLAINS AND MO RIVER VALLEY ON THURSDAY. GFS/ECMWF IN VERY GOOD
AGREEMENT THAT SFC LOW LIFTS TOWARD UPR MISSISSIPPI RIVER VALLEY BY
DAYBREAK FRIDAY AND WEAKENS WHILE MOVING INTO UPR LAKES LATE FRIDAY.
SWATH OF LGT SNOW COMES IN FROM SOUTHWEST LATE THURSDAY NIGHT AND A
GENERAL DECAYING TREND TO SNOW CONTINUES ON FRIDAY...THOUGH AT LEAST
LGT ACCUMS WILL AFFECT MUCH OF UPR MICHIGAN ON FRIDAY. POPS HIGH
CHANCE FOR NOW BUT IF MODELS REMAIN IN GOOD AGREEMENT COULD
EVENTUALLY SEE NEED FOR LIKELY POPS THU NIGHT INTO FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1240 PM EST SUN FEB 17 2013
EXPECT VFR CONDITIONS TO DECREASE TONIGHT AS A LOW PRESSURE SYSTEM
MOVES IN FROM THE WEST. LLWS IS POSSIBLE TONIGHT AT ALL SITES WITH
STRONG SOUTHERLY FLOW AHEAD OF THE LOW PRESSURE SYSTEM...BUT THINK
IT WILL BE GUSTY ENOUGH TO KEEP LLWS OUT OF THE TAF. MAIN WEATHER
THIS TAF PERIOD IS SOME LIGHT SNOW AT CMX TONIGHT...AND FREEZING
DRIZZLE AT SAW DUE TO UPSLOPE SE WINDS...AMPLE LOW LEVEL MOISTURE
AND NO MOISTURE IN THE ICE PRODUCING LATER ALOFT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 514 AM EST SUN FEB 17 2013
AS HIGH PRES SHIFTS TO THE EAST...A LOW PRESSURE SYSTEM WILL
APPROACH THE UPPER GREAT LAKES ON MONDAY AND MOVE THROUGH ON
TUESDAY. THIS WILL BRING INCREASING SOUTHERLY WINDS ON MONDAY...TO
30 KTS OVER THE EAST...AND THEN STRONG NORTHERLY GALES BEHIND THE
LOW ON TUESDAY AND TUESDAY NIGHT...TO 45 KTS. THERE COULD BE A FEW
GALE FORCE GUSTS TO 35 KNOTS ON MONDAY OVER EASTERN LAKE SUPERIOR.
WITH THE HIGHER WINDS AND COLDER AIR TUESDAY INTO WEDNESDAY...HEAVY
FREEZING SPRAY IS ALSO EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR
LSZ245>251-265>267.
GALE WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY EVENING FOR
LSZ162.
GALE WATCH FROM LATE MONDAY NIGHT THROUGH WEDNESDAY AFTERNOON
FOR LSZ240>244-263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...TITUS
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
647 AM EST SUN FEB 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 514 AM EST SUN FEB 17 2013
WV IMAGERY AND RUC ANALYSIS INDICATED NNW MID/UPPER LEVEL FLOW
THROUGH THE WRN GREAT LAKES BETWEEN A TROUGH INTO THE ERN LAKES AND
A RIDGE OVER THE NRN PLAINS INTO MANITOBA. UPSTREAM ANOTHER THROUGH
AND VIGOROUS SHRTWV WAS MOVING THROUGH THE NRN ROCKIES. AT THE
SFC...A RIDGE EXTENDED FROM W OF JAMES BAY INTO UPPER MI AND WI.
WITH VERY LIGHT SYNOPTIC SCALE WINDS...LAKE INDUCED TROUGHING AND
WIND FIELDS DOMINATED LAKE SUPERIOR. LAND BREEZES ALONG WITH A WEAK
NRLY GRADIENT FLOW HAS RESULTING IN STRONGEST AREA OF LOW LEVEL CONV
OVER E CNTRL LAKE SUPERIOR FOCUSING LES INTO THE PICTURED ROCKS AND
FAR NRN SCHOOLCRAFT COUNTY. HOWEVER...SNOW INTENSITY HAS
DIMINISHED...PER RADAR REFLECTIVITY TRENDS. UPSTREAM...CLOUDS WERE
THICKENING ACROSS MN WITH WAA PATTERN AHEAD OF A TROUGH FROM SRN
SASK INTO ERN MT.
AS THE HIGH SHIFTS TO THE EAST...WINDS OVER ERN LAKE SUPERIOR WILL
FINALLY BECOME SRLY...PUSHING ANY REMAINING LES OFFSHORE. ADDITIONAL
ACCUMULATIONS AROUND AN INCH MAY BE POSSIBLE NEAR THE SHORE FROM
PICTURED ROCKS TO GRAND MARAIS. WAA WITH INCREASING SRLY WINDS AND
SUNSHINE DURING MUCH OF THE DAY WILL HELP TEMPS RECOVER QUICKLY FROM
THE FRIGID START WITH MAX READINGS CLOSER TO SEASONAL
AVERAGES...FROM AROUND 20 CNTRL TO 25 WEST.
NAM/GFS 280K-295K ISENTROPIC PROGS AND SATELLITE TRENDS SUGGEST THAT
CLOUDS WILL MOVE IN LATE TODAY AND THICKEN ACROSS THE AREA THIS
EVENING. THE STRONGEST ASCENT AND BEST CHANCE TO SATURATE THE LOWER
LEVELS IN THE VERY DRY ANTECEDENT AIRMASS WILL BE ACROSS LAKE
SUPERIOR AND THE TIP OF THE KEWEENAW. TO THE SOUTH...A LARGE PORTION
OF ANY PCPN MAY EVAPORATE BEFORE REACHING THE SFC. SO...A QPF
PATTERN MORE IN LINE WITH THE NAM WAS FAVORED. ONLY CHANCE POPS WERE
INCLUDED WITH MINIMAL IF ANY SNOW ACCUMULATIONS LESS THAN A HALF
INCH.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 514 AM EST SUN FEB 17 2013
ACTIVE WINTER PATTERN CONTINUES THROUGH THE UPCOMING WEEK. A COUPLE
SHOTS AT WIDESPREAD SYNOPTIC SNOWFALL...FIRST ON MONDAY/MONDAY NIGHT
THEN AGAIN ON FRIDAY. BETWEEN THESE SYSTEMS...ROBUST NNW-NW FLOW
LAKE EFFECT EVENT AFFECTS NORTHERN HALF OF UPR MICHIGAN TUESDAY INTO
WEDNESDAY. AFTER ABOVE NORMAL TEMPERATURES ON MONDAY IN SOUTHERLY
FLOW AHEAD OF LOW PRESSURE...TEMPERATURES MOST OF THE WEEK WILL BE
AT OR BLO NORMAL. COLDEST TIME APPEARS TO BE TUESDAY INTO WEDNESDAY.
TEMPERATURES REBOUND TO AROUND NORMAL TO CLOSE THE WEEK.
FIRST ISSUE IS LGT SNOW ON MONDAY AS UPR TROUGH AND DEEPENING
SFC-H85 LOWS MOVE TOWARD UPR LAKES FROM SCNTRL CANADA. WARM AIR
ADVECTION BATCH OF LGT SNOW SHOULD BE ONGOING TO START THE DAY
ACROSS LAKE SUPERIOR AND FAR NORTHERN CWA. INDICATIONS ARE THAT MOST
OF THIS SNOW WILL BE DIMINISHING THROUGH THE MORNING...LEAVING A
LULL OVER MUCH OF CWA UNTIL THE AFTN. AFT 18Z...SOUNDINGS INDICATE
DEEP MOISTENING FROM ABOVE H8 AS SFC-H85 LOWS DEEPEN WHILE MOVING
INTO WESTERN HALF OF UPR MICHIGAN. AT THIS POINT IS WHERE MODELS
DIVERGE IN HANDLING TRACK OF SFC LOW. GFS/ECMWF STAYING CONSISTENT
WITH SFC LOW MOVING INTO SOUTH CNTRL UPR MICHIGAN BY 00Z TUESDAY AND
MOVING JUST EAST OF UPR MICHIGAN BY 12Z TUESDAY. GEM-NH/UKMET SLOWER
AND FARTHER WEST WITH THE SFC LOW AS THEY SHOW IT OVER NORTHERN LK
MICHIGAN/STRAITS BY 12Z TUESDAY. ONLY A SUBTLE DIFFERENCE BUT IT IS
RESULT OF DEEPER/CLOSED OFF UPR TROUGH. A DEEPER SYSTEM WOULD RESULT
IN LGT-MODERATE SYNOPTIC SNOW OVER EAST HALF OF CWA THROUGH MOST OF
MONDAY NIGHT COMPARED TO GFS/ECMWF. MORE MOISTURE IS ALSO BROUGHT
INTO SYSTEM MONDAY AFTN/EVENING...SO ULTIMATELY SNOW AMOUNTS WOULD
BE CLOSE TO ADVY LEVELS. NOT GOING THAT WAY NOW...THOUGH WILL ADMIT
THE GEM-NH CONSISTENCY IS A BIT CONCERNING. EVEN SO...PRIMARY
WEST-EAST JET ENERGY STAYS LOCKED INTO SOUTHERN STREAM OF THE UPPER
TROUGH WHICH SUPPORTS GOING WITH MORE PROGRESSIVE UPR TROUGH AND A
FARTHER EAST SFC LOW TRACK. UPSHOT...A FEW INCHES OF SNOW IN THE
EAST WITH JUST AN INCH OR TWO ELSEWHERE OVR CWA. SNOW WILL BE A
WETTER TYPE SNOW...NOT THE REALLY FLUFFY VARIETY THAT HAS BEEN WITH
US LATELY.
DEEPENING UPPER TROUGH SWINGS ACROSS GREAT LAKES ON TUESDAY HELPING
TO DRAW IN MUCH COLDER AIR YET AGAIN. H85 TEMPS AT 06Z TUESDAY ONLY
AS COLD AS AROUND -13C OVR LK SUPERIOR BUT BY 18Z TUESDAY ARE
ALREADY DOWN BLO -20C. ALL THE WHILE...SINCE UPR TROUGH IS DEEPENING
OVR THE AREA...THERE IS PLENTY OF DEEPER MOISTURE PRESENT WITH
STRONG CYCLONIC N-NW FLOW. KIND OF A PSUEDO LAKE ENHANCED SETUP
THOUGH THERE DOES NOT LOOK TO BE MUCH LARGE SCALE LIFT GOING ON.
SLR/S IN THEORY SHOULD END UP OVR 30:1 BUT GIVEN STRONG WINDS OVR 30
KTS IN THE BLYR...EXPECT FRACTURING TO HOLD SLR/S DOWN TO AN AVERAGE
OF 25-30:1. FIRST PASS AT SNOW AMOUNTS INDICATES HIGH-END ADVY BUT
SIMILAR TO LAST EVENT...LONG DURATION OF THE SNOW MAY RESULT IN SNOW
TOTALS FROM LATE MONDAY NIGHT THROUGH TUESDAY NIGHT AND WEDNESDAY
OVER A FOOT IN SOME LOCATIONS. FAVORED LOCATIONS WITH EXPECTED NNW
WINDS WOULD BE MUCH OF HIGHER TERRAIN OF ONTONAGON COUNTY THROUGH
TWIN LAKES...HIGHER TERRAIN OF BARAGA AND NORTHERN MARQUETTE
COUNTY...THEN EVENTUALLY THE SNOWBELTS OVER OF THE EASTERN CWA LATER
TUESDAY THROUGH WEDNESDAY. UNLIKE RECENT LAKE SNOW EVENT...WIND/BLSN
WILL BE BIGGER ISSUE WITH WELL MIXED BLYR. EXPECT WIDESPREAD BLSN
AND REDUCED VSBY ALONG WITH MODERATE TO HEAVY SNOW SHOWERS.
SINCE WE STILL HAVE TO GET THROUGH THE WIDESPREAD SYNOPTIC LGT SNOW
MONDAY AND MONDAY EVENING AND THIS IS MAINLY A 5TH PERIOD AND BEYOND
EVENT DID NOT ISSUE ANY HEADLINES AT THIS POINT. WILL MENTION IN HWO
AND HIT UP THE BLSN AS WELL. SEEMS THAT TRAVEL MAY BE DIFFICULT NEAR
MUCH OF LK SUPERIOR TUESDAY INTO TUESDAY EVENING.
REST OF LONG TERM...LK EFFECT DIMINISHES STEADILY ON WEDNESDAY FROM
WEST TO EAST AS UPR TROUGH/DEEPER MOISTURE EXITS TO EAST. LEFT OVER
LAKE EFFECT WILL BE PLAGUED BY LOWERING INVERSION AND DIMINISHING
CYCLONIC FLOW. WEAKER LK EFFECT AND/OR FLURRIES HANG ON THROUGH
THURSDAY OVER NCNTRL CWA WITH WINDS BECOMING N/NE. DRY ELSEWHERE AS
WE AWAIT SYSTEM THAT WILL BE BRINGING SNOW TO PARTS OF NORTHERN
PLAINS AND MO RIVER VALLEY ON THURSDAY. GFS/ECMWF IN VERY GOOD
AGREEMENT THAT SFC LOW LIFTS TOWARD UPR MISSISSIPPI RIVER VALLEY BY
DAYBREAK FRIDAY AND WEAKENS WHILE MOVING INTO UPR LAKES LATE FRIDAY.
SWATH OF LGT SNOW COMES IN FROM SOUTHWEST LATE THURSDAY NIGHT AND A
GENERAL DECAYING TREND TO SNOW CONTINUES ON FRIDAY...THOUGH AT LEAST
LGT ACCUMS WILL AFFECT MUCH OF UPR MICHIGAN ON FRIDAY. POPS HIGH
CHANCE FOR NOW BUT IF MODELS REMAIN IN GOOD AGREEMENT COULD
EVENTUALLY SEE NEED FOR LIKELY POPS THU NIGHT INTO FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 645 AM EST SUN FEB 17 2013
EXPECT VFR CONDITIONS EARLY TODAY WITH HIGH PRES AND DRY AIR DOMINATING.
THE EXCEPTION WILL BE AT CMX...WHERE ONSHORE/UPSLOPE HAS WILL KEEP
SOME LAKE CLOUDS/MVFR CIGS FOR THE FIRST COUPLE HOURS OF THE TAF
PERIOD. TODAY WILL FEATURE RATHER TRANQUIL VFR WX WITH THE HIGH
DRIFTING TO THE E AND SOME INCREASING HIGH CLOUDS E OF A TROUGH
MOVING THROUGH THE NRN PLAINS. A GUSTY S WIND WILL DEVELOP AT IWD IN
THE AFTERNOON AND CONTINUE THROUGH THE EVENING AS THE PRES GRADIENT
TIGHTENS. ALTHOUGH THE CLOUDS WILL THICKEN TONIGHT...SLY FLOW OF DRY
LLVL AIR AS WELL AS DOWNSLOPE NATURE OF THE FLOW AT IWD/CMX WILL
FAVOR VFR CIGS THROUGH THE EVENING. ENOUGH LOW LEVEL MOISTURE WITH
UPSLOPE FLOW INTO CENTRAL UPPER MI IS EXPECTED TO LEAD TO MVFR CIGS
AT SAW OVERNIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 514 AM EST SUN FEB 17 2013
AS HIGH PRES SHIFTS TO THE EAST...A LOW PRESSURE SYSTEM WILL
APPROACH THE UPPER GREAT LAKES ON MONDAY AND MOVE THROUGH ON
TUESDAY. THIS WILL BRING INCREASING SOUTHERLY WINDS ON MONDAY...TO
30 KTS OVER THE EAST...AND THEN STRONG NORTHERLY GALES BEHIND THE
LOW ON TUESDAY AND TUESDAY NIGHT...TO 45 KTS. THERE COULD BE A FEW
GALE FORCE GUSTS TO 35 KNOTS ON MONDAY OVER EASTERN LAKE SUPERIOR.
WITH THE HIGHER WINDS AND COLDER AIR TUESDAY INTO WEDNESDAY...HEAVY
FREEZING SPRAY IS ALSO EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 7 AM EST THIS MORNING FOR MIZ006-
085.
LAKE SUPERIOR...
GALE WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR
LSZ245>251-265>267.
GALE WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY EVENING FOR
LSZ162.
GALE WATCH FROM LATE MONDAY NIGHT THROUGH WEDNESDAY AFTERNOON
FOR LSZ240>244-263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
517 AM EST SUN FEB 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 514 AM EST SUN FEB 17 2013
WV IMAGERY AND RUC ANALYSIS INDICATED NNW MID/UPPER LEVEL FLOW
THROUGH THE WRN GREAT LAKES BETWEEN A TROUGH INTO THE ERN LAKES AND
A RIDGE OVER THE NRN PLAINS INTO MANITOBA. UPSTREAM ANOTHER THROUGH
AND VIGOROUS SHRTWV WAS MOVING THROUGH THE NRN ROCKIES. AT THE
SFC...A RIDGE EXTENDED FROM W OF JAMES BAY INTO UPPER MI AND WI.
WITH VERY LIGHT SYNOPTIC SCALE WINDS...LAKE INDUCED TROUGHING AND
WIND FIELDS DOMINATED LAKE SUPERIOR. LAND BREEZES ALONG WITH A WEAK
NRLY GRADIENT FLOW HAS RESULTING IN STRONGEST AREA OF LOW LEVEL CONV
OVER E CNTRL LAKE SUPERIOR FOCUSING LES INTO THE PICTURED ROCKS AND
FAR NRN SCHOOLCRAFT COUNTY. HOWEVER...SNOW INTENSITY HAS
DIMINISHED...PER RADAR REFLECTIVITY TRENDS. UPSTREAM...CLOUDS WERE
THICKENING ACROSS MN WITH WAA PATTERN AHEAD OF A TROUGH FROM SRN
SASK INTO ERN MT.
AS THE HIGH SHIFTS TO THE EAST...WINDS OVER ERN LAKE SUPERIOR WILL
FINALLY BECOME SRLY...PUSHING ANY REMAINING LES OFFSHORE. ADDITIONAL
ACCUMULATIONS AROUND AN INCH MAY BE POSSIBLE NEAR THE SHORE FROM
PICTURED ROCKS TO GRAND MARAIS. WAA WITH INCREASING SRLY WINDS AND
SUNSHINE DURING MUCH OF THE DAY WILL HELP TEMPS RECOVER QUICKLY FROM
THE FRIGID START WITH MAX READINGS CLOSER TO SEASONAL
AVERAGES...FROM AROUND 20 CNTRL TO 25 WEST.
NAM/GFS 280K-295K ISENTROPIC PROGS AND SATELLITE TRENDS SUGGEST THAT
CLOUDS WILL MOVE IN LATE TODAY AND THICKEN ACROSS THE AREA THIS
EVENING. THE STRONGEST ASCENT AND BEST CHANCE TO SATURATE THE LOWER
LEVELS IN THE VERY DRY ANTECEDENT AIRMASS WILL BE ACROSS LAKE
SUPERIOR AND THE TIP OF THE KEWEENAW. TO THE SOUTH...A LARGE PORTION
OF ANY PCPN MAY EVAPORATE BEFORE REACHING THE SFC. SO...A QPF
PATTERN MORE IN LINE WITH THE NAM WAS FAVORED. ONLY CHANCE POPS WERE
INCLUDED WITH MINIMAL IF ANY SNOW ACCUMULATIONS LESS THAN A HALF
INCH.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 514 AM EST SUN FEB 17 2013
ACTIVE WINTER PATTERN CONTINUES THROUGH THE UPCOMING WEEK. A COUPLE
SHOTS AT WIDESPREAD SYNOPTIC SNOWFALL...FIRST ON MONDAY/MONDAY NIGHT
THEN AGAIN ON FRIDAY. BETWEEN THESE SYSTEMS...ROBUST NNW-NW FLOW
LAKE EFFECT EVENT AFFECTS NORTHERN HALF OF UPR MICHIGAN TUESDAY INTO
WEDNESDAY. AFTER ABOVE NORMAL TEMPERATURES ON MONDAY IN SOUTHERLY
FLOW AHEAD OF LOW PRESSURE...TEMPERATURES MOST OF THE WEEK WILL BE
AT OR BLO NORMAL. COLDEST TIME APPEARS TO BE TUESDAY INTO WEDNESDAY.
TEMPERATURES REBOUND TO AROUND NORMAL TO CLOSE THE WEEK.
FIRST ISSUE IS LGT SNOW ON MONDAY AS UPR TROUGH AND DEEPENING
SFC-H85 LOWS MOVE TOWARD UPR LAKES FROM SCNTRL CANADA. WARM AIR
ADVECTION BATCH OF LGT SNOW SHOULD BE ONGOING TO START THE DAY
ACROSS LAKE SUPERIOR AND FAR NORTHERN CWA. INDICATIONS ARE THAT MOST
OF THIS SNOW WILL BE DIMINISHING THROUGH THE MORNING...LEAVING A
LULL OVER MUCH OF CWA UNTIL THE AFTN. AFT 18Z...SOUNDINGS INDICATE
DEEP MOISTENING FROM ABOVE H8 AS SFC-H85 LOWS DEEPEN WHILE MOVING
INTO WESTERN HALF OF UPR MICHIGAN. AT THIS POINT IS WHERE MODELS
DIVERGE IN HANDLING TRACK OF SFC LOW. GFS/ECMWF STAYING CONSISTENT
WITH SFC LOW MOVING INTO SOUTH CNTRL UPR MICHIGAN BY 00Z TUESDAY AND
MOVING JUST EAST OF UPR MICHIGAN BY 12Z TUESDAY. GEM-NH/UKMET SLOWER
AND FARTHER WEST WITH THE SFC LOW AS THEY SHOW IT OVER NORTHERN LK
MICHIGAN/STRAITS BY 12Z TUESDAY. ONLY A SUBTLE DIFFERENCE BUT IT IS
RESULT OF DEEPER/CLOSED OFF UPR TROUGH. A DEEPER SYSTEM WOULD RESULT
IN LGT-MODERATE SYNOPTIC SNOW OVER EAST HALF OF CWA THROUGH MOST OF
MONDAY NIGHT COMPARED TO GFS/ECMWF. MORE MOISTURE IS ALSO BROUGHT
INTO SYSTEM MONDAY AFTN/EVENING...SO ULTIMATELY SNOW AMOUNTS WOULD
BE CLOSE TO ADVY LEVELS. NOT GOING THAT WAY NOW...THOUGH WILL ADMIT
THE GEM-NH CONSISTENCY IS A BIT CONCERNING. EVEN SO...PRIMARY
WEST-EAST JET ENERGY STAYS LOCKED INTO SOUTHERN STREAM OF THE UPPER
TROUGH WHICH SUPPORTS GOING WITH MORE PROGRESSIVE UPR TROUGH AND A
FARTHER EAST SFC LOW TRACK. UPSHOT...A FEW INCHES OF SNOW IN THE
EAST WITH JUST AN INCH OR TWO ELSEWHERE OVR CWA. SNOW WILL BE A
WETTER TYPE SNOW...NOT THE REALLY FLUFFY VARIETY THAT HAS BEEN WITH
US LATELY.
DEEPENING UPPER TROUGH SWINGS ACROSS GREAT LAKES ON TUESDAY HELPING
TO DRAW IN MUCH COLDER AIR YET AGAIN. H85 TEMPS AT 06Z TUESDAY ONLY
AS COLD AS AROUND -13C OVR LK SUPERIOR BUT BY 18Z TUESDAY ARE
ALREADY DOWN BLO -20C. ALL THE WHILE...SINCE UPR TROUGH IS DEEPENING
OVR THE AREA...THERE IS PLENTY OF DEEPER MOISTURE PRESENT WITH
STRONG CYCLONIC N-NW FLOW. KIND OF A PSUEDO LAKE ENHANCED SETUP
THOUGH THERE DOES NOT LOOK TO BE MUCH LARGE SCALE LIFT GOING ON.
SLR/S IN THEORY SHOULD END UP OVR 30:1 BUT GIVEN STRONG WINDS OVR 30
KTS IN THE BLYR...EXPECT FRACTURING TO HOLD SLR/S DOWN TO AN AVERAGE
OF 25-30:1. FIRST PASS AT SNOW AMOUNTS INDICATES HIGH-END ADVY BUT
SIMILAR TO LAST EVENT...LONG DURATION OF THE SNOW MAY RESULT IN SNOW
TOTALS FROM LATE MONDAY NIGHT THROUGH TUESDAY NIGHT AND WEDNESDAY
OVER A FOOT IN SOME LOCATIONS. FAVORED LOCATIONS WITH EXPECTED NNW
WINDS WOULD BE MUCH OF HIGHER TERRAIN OF ONTONAGON COUNTY THROUGH
TWIN LAKES...HIGHER TERRAIN OF BARAGA AND NORTHERN MARQUETTE
COUNTY...THEN EVENTUALLY THE SNOWBELTS OVER OF THE EASTERN CWA LATER
TUESDAY THROUGH WEDNESDAY. UNLIKE RECENT LAKE SNOW EVENT...WIND/BLSN
WILL BE BIGGER ISSUE WITH WELL MIXED BLYR. EXPECT WIDESPREAD BLSN
AND REDUCED VSBY ALONG WITH MODERATE TO HEAVY SNOW SHOWERS.
SINCE WE STILL HAVE TO GET THROUGH THE WIDESPREAD SYNOPTIC LGT SNOW
MONDAY AND MONDAY EVENING AND THIS IS MAINLY A 5TH PERIOD AND BEYOND
EVENT DID NOT ISSUE ANY HEADLINES AT THIS POINT. WILL MENTION IN HWO
AND HIT UP THE BLSN AS WELL. SEEMS THAT TRAVEL MAY BE DIFFICULT NEAR
MUCH OF LK SUPERIOR TUESDAY INTO TUESDAY EVENING.
REST OF LONG TERM...LK EFFECT DIMINISHES STEADILY ON WEDNESDAY FROM
WEST TO EAST AS UPR TROUGH/DEEPER MOISTURE EXITS TO EAST. LEFT OVER
LAKE EFFECT WILL BE PLAGUED BY LOWERING INVERSION AND DIMINISHING
CYCLONIC FLOW. WEAKER LK EFFECT AND/OR FLURRIES HANG ON THROUGH
THURSDAY OVER NCNTRL CWA WITH WINDS BECOMING N/NE. DRY ELSEWHERE AS
WE AWAIT SYSTEM THAT WILL BE BRINGING SNOW TO PARTS OF NORTHERN
PLAINS AND MO RIVER VALLEY ON THURSDAY. GFS/ECMWF IN VERY GOOD
AGREEMENT THAT SFC LOW LIFTS TOWARD UPR MISSISSIPPI RIVER VALLEY BY
DAYBREAK FRIDAY AND WEAKENS WHILE MOVING INTO UPR LAKES LATE FRIDAY.
SWATH OF LGT SNOW COMES IN FROM SOUTHWEST LATE THURSDAY NIGHT AND A
GENERAL DECAYING TREND TO SNOW CONTINUES ON FRIDAY...THOUGH AT LEAST
LGT ACCUMS WILL AFFECT MUCH OF UPR MICHIGAN ON FRIDAY. POPS HIGH
CHANCE FOR NOW BUT IF MODELS REMAIN IN GOOD AGREEMENT COULD
EVENTUALLY SEE NEED FOR LIKELY POPS THU NIGHT INTO FRIDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 622 PM EST SAT FEB 16 2013
THE ARRIVAL OF LARGER SCALE SUBSIDENCE/SFC HI PRES RDG WL CAUSE
LINGERING LES AT CMX/IWD TO DIMINISH THIS EVNG. WITH BACKING LLVL
FLOW TO W AND THEN S...EXPECT SKIES TO CLR AT IWD...WITH VFR
CONDITIONS SOON AFTER FCST ISSUANCE. WITH A W ONSHORE/UPSLOPE
FLOW...MVFR CIGS/SOME -SHSN OR FLURRIES WL LINGER MUCH OF THE NGT AT
CMX UNTIL WINDS BACK SUFFICIENTLY LATER TO PUSH LK CLDS TO THE N OF
THIS SITE AND VFR WX TAKES HOLD. EXPECT EXPERIENCE VFR CONDITIONS AT
SAW WITH DOWNSLOPING ACYC FLOW. SUN WL FEATURE RATHER TRANQUIL VFR
WX WITH INCRSG HI CLDS E OF LO PRES TROF MOVING THRU THE NRN PLAINS.
A GUSTY S WIND WL DVLP AT IWD IN THE AFTN AS PRES GRADIENT TIGHTENS
AHEAD OF THIS FEATURE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 514 AM EST SUN FEB 17 2013
AS HIGH PRES SHIFTS TO THE EAST...A LOW PRESSURE SYSTEM WILL
APPROACH THE UPPER GREAT LAKES ON MONDAY AND MOVE THROUGH ON
TUESDAY. THIS WILL BRING INCREASING SOUTHERLY WINDS ON MONDAY...TO
30 KTS OVER THE EAST...AND THEN STRONG NORTHERLY GALES BEHIND THE
LOW ON TUESDAY AND TUESDAY NIGHT...TO 45 KTS. THERE COULD BE A FEW
GALE FORCE GUSTS TO 35 KNOTS ON MONDAY OVER EASTERN LAKE SUPERIOR.
WITH THE HIGHER WINDS AND COLDER AIR TUESDAY INTO WEDNESDAY...HEAVY
FREEZING SPRAY IS ALSO EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 7 AM EST THIS MORNING FOR MIZ006-
085.
LAKE SUPERIOR...
GALE WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR
LSZ245>251-265>267.
GALE WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY EVENING FOR
LSZ162.
GALE WATCH FROM LATE MONDAY NIGHT THROUGH WEDNESDAY AFTERNOON
FOR LSZ240>244-263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...KC
MARINE...JLB
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1205 AM EST SUN FEB 17 2013
.AVIATION...
//DISCUSSION...
DRIER IS WORKING IN FROM THE NORTHWEST EARLY THIS MORNING...WHICH
SHOULD ALLOW TAF SITES TO GO CLEAR-SCT FROM NORTH TO SOUTH OVER THE
NEXT SEVERAL HOURS. DIURNAL STRATO-CU (2500-3500) IS EXPECTED TO
DEVELOP BY LATE MORNING...PERSISTING FOR THE AFTERNOON HOURS.
SURFACE RIDGE IN PLACE FOR THE EARLY EVENING HOURS IS EXPECTED TO
YIELD CLEAR-SCT CLOUDS ONCE AGAIN...BUT A QUICK RAMP IN MID CLOUDS
WILL OCCUR TOWARD MONDAY MORNING.
FOR DTW...ONE LAST BATCH OF SNOW SHOWERS DROPPING SOUTH FROM OAKLAND
COUNTY MAY HOLD TOGETHER AND PRODUCE MVFR SNOW 6-8Z...WITH PARTIAL
CLEARING OCCURRING SHORTLY THEREAFTER.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING HEIGHTS BELOW 5000 FEET 06-08Z...LOW
CONFIDENCE 9-15Z...WITH MEDIUM CONFIDENCE 15-01Z.
* HIGH CONFIDENCE IN PRECIPITATION TYPE BEING SNOW.
&&
.PREV DISCUSSION...ISSUED 1044 PM EST SAT FEB 16 2013
UPDATE...
UPDATED TO UPGRADE SANILAC COUNTY TO LAKE EFFECT SNOW WARNING AS
SNOW SHOWERS INDEED CONSOLIDATED INTO AN INTENSE SNOW BAND AROUND
THE PERIPHERY OF NOW WELL DEVELOPED MESO VORTICITY OVER THE
SOUTHERN EDGE OF THE LAKE. CONVECTIVE TOPS CONTINUE TO RUN AT
10KFT WITH 30-35 DBZ RETURNS COMMON ON EXETER WSO RADAR (PUSHING
30 DBZ ON KDTX 88D @ AROUND 8KFT)...SO SUSPECT 2 TO 3 INCH PER
HOUR SNOWFALL RATES IN THE CORE OF THE LARGEST BAND. ORIENTATION
OF THIS BAND AND ANOTHER WEAKER ONE JUST TO ITS NORTH SUGGEST
PARTS OF THE COUNTY WILL RECEIVE 3 TO 4 HOURS WORTH OF AT LEAST 2
INCH PER HOUR SNOW...SO 8+ INCHES WILL BE QUITE POSSIBLE.
PREV DISCUSSION...ISSUED 731 PM EST SAT FEB 16 2013
UPDATE...
WILL MAINTAIN WINTER WEATHER ADVISORY FOR HURON...SANILAC AND ST
CLAIR COUNTIES AS SYNOPTIC SCALE SNOW TRANSITIONS TO SCATTERED TO
NUMEROUS LAKE EFFECT SNOW SHOWERS THIS EVENING AS SHORTWAVE PIVOTS
EAST INTO ONTARIO.
VISIBLE SATELLITE EARLIER DENOTED TWO MAIN MESO-VORTICITY CENTERS
ENHANCING INTENSE SNOW SHOWERS OVER LAKE HURON...ONE 50 KM NORTH
OF GODERICH ONTARIO AND THE OTHER PIVOT SOUTH ONTO THE TIP OF THE
THUMB. HIRES MODELS...3KM HRRR...LOCAL 4KM WRF AND 13KM RUC...HAD
DECENT HANDLE ON EASTERNMOST VORT CENTER...BUT ALL BUT MISSED THE
WESTERNMOST CENTER.
AS THE EVENING HAS PROGRESSED...THIS WESTERN VORTICITY CENTER HAS
TRACKED THROUGH THE THUMB AND BROUGHT ISOLATED INTENSE SNOW
SHOWERS. IT HAS ALSO SEEMED TO ACCELERATE THE SOUTHWARD PIVOT OF
THE OTHER CENTER...AS COMPARED TO THE HIRES MODEL SOLUTIONS WHICH
BROUGHT A GOOD DEAL OF CONVERGENCE ON SHORE...CENTERED ON SANILAC
COUNTY. AS LONG AS THIS TREND CONTINUES (AND THE MOST RECENT 21Z
HRRR RUN SHIFTED THIS DIRECTION)...THE MOST INTENSE AND PERSISTENT
SNOW SQUALLS WILL REMAIN MAINLY OFFSHORE. STILL EXPECT 3 TO 6
INCHES OF SNOW IN LOCAL AREAS NEAR THE LAKE HURON SHORELINE AS
THIS AREA OF SNOW SHOWERS PIVOTS SOUTH AND BRUSHES THE REGION.
IF SECOND MESO VORT IS ABLE TO WOBBLE WESTWARD AT ALL LATER THIS
EVNEING AS IT WORKS IN BEHIND THE FIRST CENTER...A LAKE EFFECT SNOW
WARNING WOULD BE REQUIRED AS ECHO TOPS ON KAPX/KDTX 88DS HAVE BEEN
RUNNING AT 10+ KFT WITH EXETER WSO RADAR SHOWING 30-35 DBZ CORES
IN SIMILAR INTENSE SNOW SHOWERS. THESE TOGETHER SUPPORT 2 TO 3
INCH PER HOUR SNOWFALL RATES IN THE MOST INTENSE SQUALLS SO ANY
BANDING SETTING UP ONSHORE FOR 2 TO 3 HOURS WOULD BRING TOTALS IN
EXCESS OF 6 INCHES.
PREV DISCUSSION...ISSUED 352 PM EST SAT FEB 16 2013
SHORT TERM...THIS AFTERNOON AND TONIGHT
UPPER LEVEL WAVE AND MID LEVEL COLD POOL HAVE BROUGHT SEVERAL SNOW
SQUALLS TO SOUTHEAST MICHIGAN TODAY...DROPPING A QUICK 1 TO 2 INCHES
OF SNOW ACROSS AREAS ALONG AND SOUTH OF THE INTERSTATE 69 CORRIDOR.
HOWEVER THE SURFACE TROUGH AND PV ANOMALY HAVE YET TO TRACK THROUGH
SOUTHEAST MICHIGAN. THESE FEATURES WILL TRACK THROUGH DURING THE
EVENING HOURS AND TURN WINDS TO A NORTHERLY DIRECTION...BRINGING
COOLER AIR AND LAKE MOISTURE IN FROM LAKE HURON. ALTHOUGH THE DTX
HIRES WRF RUNS DEVELOP AN IMPRESSIVE LAKE EFFECT BAND THAT TRACKS
THROUGH THE THUMB REGION BETWEEN 21Z AND 06Z...MODEL INITIALIZATION
IS VERY POOR AS THE 20Z PANEL INDICATES THERE SHOULD BE AN
IMPRESSIVE BAND JUST OFFSHORE OF HURON COUNTY...WHICH BY THE VISIBLE
SATELLITE IMAGERY IS FAR FROM REALITY. THIS FAILURE IN THE MODEL
LOOKS TO BE THE FAILURE OF A MESOLOW TO DEVELOP ACROSS CENTRAL LAKE
HURON...INSTEAD THE LAKE EFFECT IS IN A NORTHWEST TO SOUTHEAST
ORIENTATION BEHIND THE MAIN SURFACE TROUGH. THIS IS ACTUALLY
DEPICTED RATHER WELL BY THE HRRR MODEL WHICH BRINGS THIS FEATURE
SOUTH THROUGH THE EARLY EVENING HOURS AND DEVELOPS A NORTH-SOUTH
BAND OF LAKE EFFECT SNOW ACROSS THE EASTERN THUMB WITH SIGNIFICANT
ASSISTANCE FROM CONVERGENCE AS NORTH-NORTHWEST WINDS OVER THE LAKE
CONVERGE WITH NORTHEASTERLY WINDS ACROSS SOUTHERN LAKE HURON. THIS
SETUP WOULD BRING SEVERAL INCHES OF ACCUMULATING SNOW TO SANILAC AND
ST. CLAIR COUNTIES DURING THE EVENING HOURS UNTIL LAKE WINDS TURN
MORE NORTHERLY AND CONVERGENCE ALONG THE LAKE BECOMES BROADER. TO
ADD TO THE CONFUSION THE NAM MODEL IS VERY BRIEF WITH THE
CONVERGENCE AND KEEPS MOST OF THE LAKE EFFECT SNOW OFFSHORE DURING
THE EVENING HOURS.
GIVEN THE GOOD INITIALIZATION INCLINATION IS TO LEAN TOWARDS THE
HRRR SOLUTION AS EAST-WEST BANDS TEND TO TRANSITION TO NORTH-SOUTH
AS THEY ENCOUNTER THE TOPOGRAPHY OF THE THUMB REGION...HOWEVER
CANNOT RULE OUT THE POSSIBILITY OF A MESOLOW FORMING AND TRACKING
FARTHER INLAND THAN SANILAC AND ST. CLAIR COUNTIES. THEREFORE WILL
HANG ONTO THE WINTER WEATHER ADVISORY FOR THE THUMB REGION AND LET
LATER SHIFTS PARE DOWN THE HEADLINE AS THE NATURE AND ORIENTATION OF
THE LAKE EFFECT BECOME APPARENT DURING THE EVENING HOURS. THE
PREVIOUS FORECAST AMOUNTS STILL LOOK SOLID IN THIS REGION WITH A
GOOD 2 TO 4 INCHES EXPECTED WITH ISOLATED 6 INCH AMOUNTS NEAR THE
LAKE HURON SHORELINE AREAS.
LONG TERM...SUNDAY THROUGH FRIDAY
VERY STRONG NEGATIVE POTENTIAL VORTICITY ADVECTION FROM RETREATING
LARGE WAVELENGTH UPPER LEVEL TROUGH WILL LEAD TO RAPID 1000-500MB
GEOPOTENTIAL HIGH RISES OVER SOUTHEASTERN MICHIGAN 12-00Z SUNDAY.
THE MAXIMUM OF GEOPOTENTIAL HEIGHT RISES WILL REMAIN OVER THE
SOUTHERN APPALACHIANS IN RESPONSE TO THE BOMBING
NOR`EASTER...HOWEVER...HEIGHT RISE RIDGE AXIS WILL EXTEND NORTHWARD
INTO CENTRAL GREAT LAKES. REMNANT LAKE EFFECT WILL BE ONGOING OVER
SOUTH LAKE HURON THROUGH SUNDAY AFTERNOON BEFORE SWEEPING EASTWARD
DUE TO INCREASING WESTERLY COLUMN FLOW. HIGH TEMPERATURES TOMORROW
WILL BE CONSIDERABLY COLD...SOME 10-13 DEGREES BELOW NORMAL. A
RATHER RAW DAY WITH JUST ENOUGH WIND MAGNITUDE TO ALLOW FOR WIND
CHILL VALUES IN THE SINGLE DIGITS BEFORE NOON...TOPPING OUT BETWEEN
10-15 DEGREES FOR THE AFTERNOON. TYPICAL QUESTION MARK EXISTS
CONCERNING POTENTIAL FOR STRATOCUMULUS TOMORROW. THE AREAS
POSITION/PROXIMITY WITHIN EDGE OF RETREATING TROUGH AND OVERALL
ARCTIC AIRMASS SUGGESTS SUNSHINE WILL GREET US IN THE MORNING. THIS
CERTAINLY HAS SUPPORT WHEN LOOKING AT SATELLITE IMAGERY OVER
NORTHERN MINNESOTA. THE MODELED INVERSION AT ROUGHLY 5 KFT AGL IS
INTERESTING AS THE SOLUTION SHOWS NO MOISTURE TRAPPED WITHIN THE
STABLE STRATIFIED LAYER IMMEDIATELY ABOVE INVERSION BASE OR EVEN AT
THE INVERSION BASE ITSELF. WILL CONTINUE WITH THE INHERITED FORECAST
WHICH CALLS FOR SUNSHINE TOMORROW.
MODELS ARE COMING INTO AN AGREEMENT WITH THE SYSTEM THAT WILL
APPROACH THE AREA MONDAY NIGHT. OVERALL...SYSTEM DYNAMICAL SUPPORT
APPEARS ABOVE AVERAGE AS THE SOUTHERN EXTENSION OF THE MIDLEVEL
TROUGH WILL BECOME LINKED TO SOUTHERN STREAM JET STREAM ENERGY OVER
THE FOUR CORNERS AREA SUNDAY NIGHT. THE TROUGH AXIS WHICH WILL BEGIN
AT A POSITIVE TILT WILL TURN NEUTRAL MONDAY NIGHT AND EVENTUALLY
NEGATIVE BY TUESDAY MORNING. THE PRECEDING WARM AIR ADVECTION...WING
OF ISENTROPIC LIFT IS SHOWN TO BE DRY. IT WILL REQUIRE ACTUAL
MOISTURE TRANSPORT AND UPPER LEVEL JET SUPPORT TO GET PRECIPITATION
GOING. DELAYED PRECIPITATION ONSET TIMING A FEW HOURS...NOW EXPECTED
MAINLY FOR THE FIRST HALF OF MONDAY NIGHT. THE GFS SOLUTION AND
RESULTANT PRECIPITATION TYPE SEEMS HIGHLY SUSPECT GIVEN THE OVERALL
HEIGHT PATTERN AND FORECASTED WIND FIELD. REST OF THE MEDIUM RANGE
SUITE SUGGESTS THAT A SUBSTANTIAL WARM LAYER FROM SFC-5 KFT AGL WILL
SLIDE IN SUPPORTING A RAPID TRANSITION TO RAIN. FROM THIS VANTAGE
POINT THIS SYSTEM HAS THE POTENTIAL TO BECOME A HIGHER IMPACT WIND
EVENT. RIGHT NOW...FORECASTED VALUES OF UPWARDS OF 30 KNOTS SEEMS
GOOD...WITH ALL THE MAIN FEATURE SLIGHTLY OUT OF PHASE. SUBSEQUENT
SHIFTS CAN FINE TUNE THIS.
MARINE...
OTHER THAN AN ACTIVE SNOW SHOWER PATTERN TONIGHT...MARINE CONDITIONS
WILL BE FAVORABLE THROUGH SUNDAY IN TERMS OF WIND OVER ALL MARINE
AREAS AND WAVES OVER THE OPEN WATERS OF LAKE HURON. AFTER THAT...A
STRONG LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP OVER THE PLAINS
AND MIDWEST AND MOVE THROUGH THE GREAT LAKES MONDAY AND TUESDAY.
MILD AIR SPREADING NORTHWARD AHEAD OF THE SYSTEM WILL BRING RAIN TO
ALL AREAS EXCEPT THE FAR NORTH REACHES OF LAKE HURON. A STRONG COLD
FRONT IS EXPECTED TO BRING A SHARP WESTERLY WIND SHIFT TUESDAY
MORNING BUT SPEEDS ARE EXPECTED TO REMAIN BELOW GALE FORCE FOR
NOW. STRONG NORTHWEST WIND TRAILING THE FRONT WILL EASE IN SPEED
DURING WEDNESDAY.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...LAKE EFFECT SNOW WARNING...MIZ055...UNTIL 2 AM SUNDAY.
WINTER WEATHER ADVISORY...MIZ063...UNTIL 2 AM SUNDAY.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....SF
UPDATE.......DG
SHORT TERM...KURIMSKI
LONG TERM....CB
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
558 AM CST SUN FEB 17 2013
.SHORT TERM...
ISSUED AT 311 AM CST SUN FEB 17 2013
(TODAY)
WINDS WILL BECOME SELY TODAY AS A SFC RIDGE AXIS SHIFTS EAST OF THE
AREA. TEMPERATURES ALOFT WILL RISE DURING THE DAY AS THE UPPER LEVEL
RIDGE ALSO SHIFTS EWD. ALTHOUGH NO MODEL IS HANDLING THE PATCH OF
WAA CLOUDS OVERHEAD VERY WELL...RAP FCSTS OF CONDENSATION PRESSURE
DEFICITS BETWEEN 875-800MB DO SUGGEST SOME THINNING WILL OCCUR BY
18Z AS THE THICKER CLOUDS SHIFT SOUTHEAST OF THE CWA. GIVEN THESE
EXPECTED CLOUD TRENDS AND A SLY WIND COMPONENT...AFTN HIGHS IN THE
MID 40S TO MID 50S LOOK REASONABLE BASED ON 21Z T85 FCSTS OF -4 TO 0
DEG C WITH AFTN MIXING TO BETWEEN H9-H85.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 311 AM CST SUN FEB 17 2013
THE UPCOMING WEEK WILL BE DOMINATED BY TWO STORM SYSTEMS...ONE ON
MONDAY AND THE OTHER PRIMARILY FOR THURSDAY.
(TONIGHT - MONDAY NIGHT)
A STRONG SHORTWAVE OVER THE PAC NW ATTM WILL RAPIDLY TRANSLATE E IN
A LONGWAVE FLOW THAT IS TRANSITIONAL...AS ONE LONGWAVE TROF EXITS
OFF THE ERN CONUS AND ANOTHER IS EXPECTED TO MOVE INTO THE WRN CONUS
BY MID-WEEK. STRONG LO LEVEL JET OF 65KTS EXPECTED TO DEVELOP THIS
EVENING WILL HELP FUNNEL GULF OF MEXICO MOISTURE INTO THE MID MS
VALLEY ON MONDAY JUST AS THE DEEPER LIFT FROM THE SHORTWAVE
APPROACH. THE RESULT SHOULD BE RAPIDLY DEVELOPING PCPN ON MONDAY
THRU EARLY AFTERNOON WITH THE PCPN THEN SHOVING OFF TO THE E DURING
THE EVENING. VERTICAL TEMP PROFILES TOO WARM FOR ANYTHING BUT
LIQUID PCPN FOR THE EVENT...BUT FCST SOUNDINGS DO INDICATE
SUFFICIENT INSTABILITY TO SUPPORT SOME THUNDER THAT IS ELEVATED IN
NATURE...ALTHOUGH WITH SKINNY CAPES INDICATED...SHOULD SEE SHRA WITH
EMBEDDED TSRA AND THIS IS WELL HANDLED BY PREVIOUS FCST ALREADY AND
SO LET RIDE. SFC-BASED CONVECTION SEEMS REMOTE WITH DWPTS NOT
EXPECTED TO EXCEED 50F.
LIKELY-CATEGORICAL POPS STILL LOOK GOOD...WITH THE HIGHEST POPS FOR
STL METRO AND S AND E DURING MONDAY AFTERNOON.
THE STRONG LO LEVEL JET WILL ALSO CREATE ANOTHER PROBLEM...NAMELY
THE POTENTIAL TO MIX DOWN TO THE SFC. MODELS INDICATE SPEEDS OF
60KTS AS LO AS JUST 2KFT OFF THE SFC AND MIXING HEIGHTS...WHILE
LO...WILL HAVE THE ABILITY TO TAP GUSTS APPROACHING ADVISORY
CRITERIA OF 45MPH...ESPECIALLY IN AREAS TO THE S AND E OF STL
METRO. HAVE BUMPED UP GUSTS TO 40MPH IN THESE AREAS FOR NOW.
TEMPS WILL DO MUCH...IF NOT ALL...OF THEIR DROP THIS EVENING BEFORE
STRONGER S FLOW KICKS IN AND CLOUDS THICKEN. AT THAT POINT...LOOK
FOR STEADY OR SLOWLY RISING OVERNIGHT. MONDAY MOS TEMPS LOOK TOO
WARM IN SPOTS...NAMELY FOR STL METRO...BUT OTHERWISE LO-MID 50S
FOR MOST LOCALES LOOKS GOOD.
(TUESDAY - WEDNESDAY)
A COLD AIRMASS WILL TAKE HOLD DURING THIS PERIOD...WITH IT JUST
STARTING TO GET ESTABLISHED ON TUESDAY AND IT SHOULD BE WELL
ENTRENCHED INTO THE AREA ON WEDNESDAY. FAVORED WARMER END OF MOS ON
TUESDAY WITH GOOD SUNSHINE EXPECTED AND DEEP MIXING...MOS SEEMS TO
BE CONSISTENTLY TOO COOL IN THESE SITUATIONS. WEDNESDAY EXPECTED TO
BE COLDER WITH COLDER EARLY MORNING START...NE-E FLOW...AND
INCREASING CLOUDS.
(THURSDAY - SATURDAY)
WITH LONGWAVE TROF ANTICIPATED TO REFORM OVER THE WRN CONUS...WE
WILL BEGIN TO SEE STORMS APPROACH FROM THE SW AGAIN AND THE THURSDAY
STORM WILL BE THE FIRST IN THAT SERIES.
AN INITIAL IMPULSE...WHICH IS COMMON IN THESE TYPES OF STORMS...WILL
SHOOT OUT AHEAD OF THE MAIN STORM AND PERHAPS AFFECT THE AREA LATE
WEDNESDAY NIGHT WITH THE MAIN EVENT STILL ON TRACK FOR THURSDAY AND
PERHAPS A PERIOD OF DRIZZLE THURSDAY NIGHT AS THE OCCLUDED FRONT
MOVES THRU IN REGION OF CYCLONIC LO LEVEL FLOW AND SLOWLY RETREATING
LO CLOUD.
VERY FEW CHANGES MADE TO CURRENT FCST WITH RESPECT TO PCPN-TYPES AND
TIMING AS IT STILL LOOKS ON TARGET WITH THE DATA WE HAVE. OCCLUDED
SYSTEM CENTER TO PASS TO OUR NW...BUT THAT IS THE KEY...OCCLUDED
SYSTEM...WITH COLD AIR AT THE LO LEVELS TO REMAIN IN PLACE ACROSS
THE FA...THE MAIN WARM SECTOR STAYING TO THE S. AS IT STANDS
NOW...WAA EVENT WILL FEATURE A WINTRY MIX ACROSS THE FA... WITH
MAINLY SNOW AND SLEET IN NERN MO AND W-CNTRL IL...FZRA/RA FOR AREAS
FURTHER S...DEPENDING ON EXACTLY WHERE THE 32F LINE IS AT THE SFC.
AND THAT IS ANOTHER THING TO KEEP IN MIND...SKILL AT FCSTG 32F LINE
SIMPLY NOT SUFFICIENT AT THIS TIME TO SAY WHO WILL RECEIVE A HIGH
IMPACT EVENT AND WHO WILL NOT. BUT BASED ON OUR CURRENT
DETERMINISTIC FCST...COULD SEE FAIRLY SIZABLE SNOW AND ICE ACCUMS BY
THE TIME IT IS ALL SAID AND DONE...WITH THE BEST PROBS FOR THIS WILL
BE ALG-N OF I-70. PERIODS OF FZDZ-DZ THEN LOOKS TO BE A GOOD BET
FOR THURS NGT.
BELOW AVERAGE TEMPS THEN EXPECTED FOR FRIDAY AND SATURDAY. SEVERAL
ADDITIONAL DISTURBANCES WILL PUSH THRU IN THE WAKE OF THE THURSDAY
STORM...BUT MOISTURE WILL BE LIMITED...UNLESS A SYSTEM CAN GENERATE
ENOUGH LIFT. ONLY PLACED IN SLIGHT CHC POPS FOR SATURDAY.
TES
&&
.AVIATION...
ISSUED AT 537 AM CST SUN FEB 17 2013
THE 6-8 KFT CLOUD DECK THAT WAS LOCATED OVER THE TERMINALS AT TAF
ISSUANCE IS EXPECTED TO SHIFT SEWD AND THIN OUT OVER THE NEXT
SEVERAL HOURS BASED ON RAP FCSTS OF CONDENSATION PRESSURE
DEFICITS. SFC WINDS WILL BECOME SELY TODAY THEN INCREASE TONIGHT
ONCE THE PRESSURE GRADIENT TIGHTENS AHEAD OF AN APPROACHING LOW
PRESSURE SYSTEM. A LOW LEVEL JET WILL ALSO DEVELOP TONIGHT AND
PRODUCE LLWS CONDITIONS FROM LATE TONIGHT THROUGH EARLY TOMORROW
MORNING. BEYOND THE END OF THE 24 HR TAF PD...RAIN SHOWERS ARE
EXPECTED TO SPREAD ACROSS THE REGION WITH CIG/VIS RESTRICTIONS
LIKELY.
SPECIFICS FOR KSTL...VFR CONDITIONS ARE EXPECTED FOR AT LEAST THE
FIRST 12-18 HOURS OF THE TAF PD. THE 6-8 KFT CLOUD DECK THAT WAS
LOCATED OVER KSTL AT TAF ISSUANCE IS EXPECTED TO SHIFT SEWD AND
THIN OUT OVER THE NEXT SEVERAL HOURS. SFC WINDS BECOME SELY TODAY
THEN INCREASE TONIGHT ONCE THE PRESSURE GRADIENT TIGHTENS AHEAD OF
AN APPROACHING LOW PRESSURE SYSTEM. A LOW LEVEL JET WILL DEVELOP
TONIGHT AND PRODUCE LLWS CONDITIONS FROM LATE TONIGHT THROUGH
EARLY TOMORROW MORNING. RAIN SHOWERS WITH CIG/VIS RESTRICTIONS ARE
EXPECTED TOMORROW MORNING AT KSTL.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS RALEIGH NC
626 AM EST SUN FEB 17 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL BUILD TOWARD THE CAROLINAS FROM THE
SOUTHWEST TODAY AS A RAPIDLY INTENSIFYING LOW PRESSURE SYSTEM
OFFSHORE THE MID ATLANTIC COAST TRACKS NORTHEAST TOWARD THE CANADIAN
MARITIMES. HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT BEFORE
MOVING OFFSHORE LATE MONDAY INTO MONDAY NIGHT AS A COLD FRONT
APPROACHES THE MOUNTAINS FROM THE WEST.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 255 AM SUNDAY...
THIS MORNING:
A LINGERING NNW-SSE ORIENTED BAND OF SNOW OVER THE COASTAL PLAIN
WILL CONTINUE TO WEAKEN...DISSIPATING BY 300-330 AM AS THE UPPER
LEVEL TROUGH AXIS PROGRESSES EAST OF CENTRAL NC AND STRENGTHENING
SYNOPTIC SUBSIDENCE RESULTS IN RAPID DRYING ALOFT. AS MUCH AS 1.0 TO
1.5 INCHES OF SNOW ACCUMULATION OCCURRED IN ASSOCIATION WITH THIS
BAND OVER GRANVILLE...VANCE...FRANKLIN...EASTERN WAKE... JOHNSTON...
WAYNE AND EASTERN SAMPSON COUNTIES BETWEEN 900 PM SATURDAY EVENING
AND 200 AM THIS MORNING. EXPECT DANGEROUS ROAD CONDITIONS ALONG THE
INTERSTATE 85 CORRIDOR FROM DURHAM NORTH TO THE VIRGINIA
BORDER...ALONG THE INTERSTATE 40 CORRIDOR FROM RALEIGH EAST TO
BENSON-HOBBTON-WARSAW...AND ALONG THE INTERSTATE 95 CORRIDOR FROM
BENSON NORTH TO ROANOKE RAPIDS. HAVE HIGHLIGHTED THESE AREAS IN THE
WINTER WEATHER ADVISORY THAT REMAINS IN EFFECT UNTIL 10 AM THIS
MORNING...WHEN TEMPERATURES ARE EXPECTED TO RISE ABOVE FREEZING.
ADDITIONAL SHORTWAVE ENERGY APPROACHING WEST VIRGINIA AT 07Z IS
PROGGED TO TRACK SOUTHEAST THROUGH SOUTHERN VA AND NORTHEAST NC
BETWEEN 12-15Z THIS MORNING...IN THE PRESENCE OF LINGERING LOW-LEVEL
MOISTURE AND STEEP MID-LEVEL LAPSE RATES (7-7.5 C/KM) OVER THE N/NE
OF THE TRIANGLE INTO CENTRAL/SOUTHEAST VA (PER 00Z RAOB AND THE
LATEST RAP MODEL DATA). IT IS POSSIBLE THAT FLURRIES MAY OCCUR N AND
NE OF THE TRIANGLE TOWARD THE VA BORDER (ROXBORO EAST TO ROANOKE
RAPIDS) BETWEEN 09-15Z WHERE DPVA IN THE PRESENCE OF STEEP MID-LEVEL
LAPSE RATES AND LINGERING LOW-LEVEL MOISTURE IN THE ICE NUCLEATION
ZONE MAY (BARELY) OVERCOME STRENGTHENING SUBSIDENCE ALOFT...THOUGH
NO MEASURABLE PRECIPITATION WOULD BE EXPECTED. 07Z RADAR DATA FROM
KFCX LENDS CREDENCE TO THIS POSSIBILITY.
THIS AFTERNOON THROUGH TONIGHT:
PRONOUNCED DRYING ALOFT (ESPECIALLY 8+ KFT AGL) WILL OCCUR
THROUGHOUT THE DAY AS THE UPPER LEVEL TROUGH AXIS PROGRESSES
OFFSHORE THE MID-ATLANTIC AND CAROLINA COAST. LOW-LEVEL MOISTURE
PROGGED TO ADVECT INTO THE REGION FROM THE NW UNDERNEATH THE
STRENGTHENING MID-LEVEL SUBSIDENCE INVERSION MAY ALLOW FOR SCATTERED
CLOUD COVER WITH BASES AT 5-7 KFT AGL TODAY. OTHERWISE...EXPECT
MOSTLY SUNNY SKIES. 1000-850 MB THICKNESSES AND H85 TEMPS SUGGEST
CHILLY TEMPS TODAY...RANGING FROM THE MID 30S N/NE TO UPPER 30S AND
LOWER 40S FAR S/SW. 25-35 KT FLOW NW FLOW IN THE MIXED LAYER
(STRONGEST THROUGH 18Z) WILL RESULT IN BREEZY CONDITIONS...
ESPECIALLY N/NE OF THE TRIANGLE. EXPECT SUSTAINED NW WINDS AT 10-20
MPH WITH GUSTS GENERALLY IN THE 20-30 MPH RANGE...THOUGH SPORADIC
HIGHER GUSTS UP TO 35 MPH WILL BE POSSIBLE. EXPECT WIND CHILL VALUES
IN THE TEENS (PRIMARILY NORTH OF HWY 64) THIS MORNING...AND
LINGERING IN THE 20S THIS AFTERNOON...ESPECIALLY IN THE NORTH. WITH
A COLD/DRY AIRMASS IN PLACE...CLEAR SKIES AND AND CALM WINDS TONIGHT
AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION FROM THE
SOUTHWEST... EXPECT EXCELLENT RADIATIONAL COOLING WITH CHILLY LOWS
RANGING FROM THE MID/UPPER TEENS IN RURAL/LOW-LYING AREAS TO LOWER
20S IN URBAN AREAS. -VINCENT
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
AS OF 300 AM SUNDAY...
AS THE COLD MODIFIED ARCTIC SURFACE HIGH SLIPS EAST AND OFFSHORE
MONDAY... THE RETURN FLOW WILL BRING A STRONG WARMING TREND BY
AFTERNOON. HOWEVER... THE AIR MASS WILL REMAIN DRY AND WITH THE
BREEZY WINDS (EVEN IF THEY ARE FROM THE SW) IT WILL STILL FEEL
RATHER CHILLY. HIGHS 50-55 EXPECTED WITH MOSTLY SUNNY SKIES.
INCREASING MID AND HIGH LEVEL MOISTURE WILL LEAD TO PARTLY CLOUDY
BECOMING MOSTLY CLOUDY SKIES MONDAY NIGHT. LOWS WILL BE MUCH MILDER
WITH LOWS IN THE UPPER 30S TO MID 40S.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 317 AM SUNDAY...
THE MAIN STORM TRACK WITH THE NEXT APPROACHING SYSTEM IS EXPECTED TO
BE FROM THE MIDWEST NE ACROSS THE GREAT LAKES TUE-TUE NIGHT. THE
TRAILING COLD FRONT IS EXPECTED TO PUSH EAST ACROSS OUR REGION
TUESDAY. INITIALLY... A STRONG AND MOIST FLOW FROM THE GULF WILL
ALLOW FOR SIGNIFICANT RAIN INTO THE TENNESSEE VALLEY INTO FAR
WESTERN NC INTO MONDAY NIGHT. HOWEVER... AS THE STORM MOVES OVER THE
GREAT LAKES... THE MEAN FLOW IS EXPECTED TO BECOME PROGRESSIVELY
MORE WESTERLY AS THE SYSTEM MOVES ACROSS THE APPALACHIANS TO THE
MID-ATLANTIC COAST TUESDAY AFTERNOON AND EVENING. THIS EFFECTIVELY
SHUTS DOWN THE GULF INFLOW AS THE COLD FRONT MOVES THROUGH CENTRAL
NC. WE WILL CONTINUE TO CARRY HIGH POPS BUT LOW QPF. MOST AREAS
SHOULD SEE LESS THAN 0.25 WITH EASTERN ZONES POSSIBLY LESS THAN
0.10. THE LIKELY POP WILL BE CONFINED TO TUESDAY... WITH RAPIDLY
DECREASING POP TUESDAY EVENING FROM WEST TO EAST AS THE COLD FRONT
REACHES THE COAST. HIGHS TUESDAY WILL BE HELD DOWN DUE TO THE CLOUDS
AND SHOWERS. EXPECT SOME 40S TO HOLD ON OVER THE PIEDMONT... WITH
50S SE. SKIES WILL BECOME PARTLY CLOUDY TUESDAY NIGHT WITH CAA
LEADING TO LOWS OF 30-35.
WED-THU... VERY COLD AND STRONG ARCTIC HIGH PRESSURE WILL AFFECT THE
UPPER MIDWEST AND GREAT LAKES. THIS HIGH PRESSURE IS FORECAST TO
BUILD SOUTH INTO NC THIS PERIOD. HOWEVER... THE CORE OF THE ARCTIC
AIR IS FORECAST TO REMAIN FROM AROUND NORTHERN VA NORTHWARD. YET...
THE FEED OF DRY AND COLD AIR WILL ALLOW TEMPS TO FALL BELOW NORMAL
WED NIGHT AND THURSDAY. MOSTLY CLEAR SKIES ARE EXPECTED WED-THU...
HIGHS WED SHOULD BE IN THE UPPER 40S TO MID 50S... COOLING INTO THE
MID 40S TO LOWER 50S THURSDAY. LOWS WED SHOULD BE 25-30.
BY FRIDAY... ANOTHER STORM SYSTEM IS EXPECTED TO FOLLOW THE SAME
GENERAL TRACK AS THE LAST SEVERAL STORMS... FROM THE PLAINS TO THE
GREAT LAKES. HOWEVER... THE LARGE COLD SURFACE HIGH SHOULD BE
LOCATED OVER NEW ENGLAND THU NIGHT... THEN SLOWLY DRIFT EAST BY
FRIDAY AND FRIDAY NIGHT. THE HIGH IS FORECAST TO BE MORE THAN STRONG
ENOUGH... AND IN MORE THAN ADEQUATE POSITION TO FAVOR A CLASSICAL TO
HYBRID CAD EVENT FOR FRI-FRI NIGHT AS THE PRECIPITATION ASSOCIATED
WITH THE STORM SYSTEM ARRIVES FROM THE WEST. FOR NOW... IT DOES
APPEAR TO BE WARM ENOUGH FOR RAIN... ALTHOUGH THIS WILL HAVE TO BE
WATCHED CLOSELY FOR FRIDAY. LOWS 30-35. HIGHS 38-48 NW TO SE.
THE FRONT SHOULD SETTLE SOUTH OF THE REGION OVER THE WEEKEND... WITH
ANOTHER POTENTIAL STORM WITH SIGNIFICANT PRECIPITATION OVER THE SE
INTO THE MID-ATLANTIC LATER IN THE WEEKEND. THE POTENTIAL STORM
TRACK FROM THE GULF TO THE SE STATES ALLOWS POTENTIAL FOR WINTERY
PRECIP INTO THE MID-ATLANTIC STATES... BUT THE QUESTION WILL BE THE
POSITION AND STRENGTH OF THE SURFACE HIGH THAT WILL FOLLOW THE
FRONT FRIDAY... AND HOW FAR SOUTH THE COLD AIR CAN REACH.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AS OF 625 AM SUNDAY...
24-HR TAF PERIOD:
VFR CONDITIONS WILL RULE THROUGH THE TAF PERIOD AS AN INTENSIFYING
LOW PRESSURE SYSTEM TRACKS FURTHER OFFSHORE INTO THE ATLANTIC. THE
PRIMARY AVIATION CONCERN WILL BE BREEZY WNW/NW WINDS TODAY...
SUSTAINED AT 15 KT WITH GUSTS GENERALLY TO 25 KT...THOUGH A PERIOD
OF STRONGER WINDS SUSTAINED AT 20 KT WITH GUSTS UP TO 30 KT WILL BE
POSSIBLE...PRIMARILY BETWEEN 12-18Z...ESPECIALLY AT THE RWI
TERMINAL. WINDS WILL DECREASE TO 5-10 KT AFTER 21Z...BECOMING LIGHT
AND VARIABLE AFTER 00Z.
LOOKING AHEAD:
VFR CONDITIONS WILL RULE THROUGH MONDAY IN ASSOCIATION WITH DRY HIGH
PRESSURE. HIGH PRESSURE WILL MOVE OFFSHORE MONDAY NIGHT AS A COLD
FRONT APPROACHES THE MOUNTAINS FROM THE WEST. EXPECT DETERIORATING
CONDITIONS WITH MVFR/IFR CEILINGS DEVELOPING IN ASSOC/W AN
INCREASINGLY MOIST RETURN FLOW BETWEEN 06-12Z TUE AND INCREASING
CHANCES FOR RAIN FROM WEST-EAST BETWEEN 12-18Z TUE. A PERIOD OF
SOUTHWESTERLY LOW LEVEL WIND SHEAR WILL BE POSSIBLE BETWEEN 06Z TUE
MORNING AND 18Z TUE AFTERNOON AS A 40-45 KT LLJ DEVELOPS AS LOW DOWN
AS 1500-2000 FT AGL. EXPECT RAPID CLEARING AND A RETURN TO VFR
CONDITIONS IN THE WAKE OF THE COLD FRONTAL PASSAGE LATE TUE INTO TUE
NIGHT. VFR CONDITIONS WILL PREVAIL THROUGH THURSDAY AS DRY HIGH
PRESSURE BUILDS OVER THE CAROLINAS. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 10 AM EST SUNDAY FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
315 AM EST SUN FEB 17 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL BUILD TOWARD THE CAROLINAS FROM THE
SOUTHWEST TODAY AS A RAPIDLY INTENSIFYING LOW PRESSURE SYSTEM
OFFSHORE THE MID ATLANTIC COAST TRACKS NORTHEAST TOWARD THE CANADIAN
MARITIMES. HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT BEFORE
MOVING OFFSHORE LATE MONDAY INTO MONDAY NIGHT AS A COLD FRONT
APPROACHES THE MOUNTAINS FROM THE WEST.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 255 AM SUNDAY...
THIS MORNING:
A LINGERING NNW-SSE ORIENTED BAND OF SNOW OVER THE COASTAL PLAIN
WILL CONTINUE TO WEAKEN...DISSIPATING BY 300-330 AM AS THE UPPER
LEVEL TROUGH AXIS PROGRESSES EAST OF CENTRAL NC AND STRENGTHENING
SYNOPTIC SUBSIDENCE RESULTS IN RAPID DRYING ALOFT. AS MUCH AS 1.0 TO
1.5 INCHES OF SNOW ACCUMULATION OCCURRED IN ASSOCIATION WITH THIS
BAND OVER GRANVILLE...VANCE...FRANKLIN...EASTERN WAKE... JOHNSTON...
WAYNE AND EASTERN SAMPSON COUNTIES BETWEEN 900 PM SATURDAY EVENING
AND 200 AM THIS MORNING. EXPECT DANGEROUS ROAD CONDITIONS ALONG THE
INTERSTATE 85 CORRIDOR FROM DURHAM NORTH TO THE VIRGINIA
BORDER...ALONG THE INTERSTATE 40 CORRIDOR FROM RALEIGH EAST TO
BENSON-HOBBTON-WARSAW...AND ALONG THE INTERSTATE 95 CORRIDOR FROM
BENSON NORTH TO ROANOKE RAPIDS. HAVE HIGHLIGHTED THESE AREAS IN THE
WINTER WEATHER ADVISORY THAT REMAINS IN EFFECT UNTIL 10 AM THIS
MORNING...WHEN TEMPERATURES ARE EXPECTED TO RISE ABOVE FREEZING.
ADDITIONAL SHORTWAVE ENERGY APPROACHING WEST VIRGINIA AT 07Z IS
PROGGED TO TRACK SOUTHEAST THROUGH SOUTHERN VA AND NORTHEAST NC
BETWEEN 12-15Z THIS MORNING...IN THE PRESENCE OF LINGERING LOW-LEVEL
MOISTURE AND STEEP MID-LEVEL LAPSE RATES (7-7.5 C/KM) OVER THE N/NE
OF THE TRIANGLE INTO CENTRAL/SOUTHEAST VA (PER 00Z RAOB AND THE
LATEST RAP MODEL DATA). IT IS POSSIBLE THAT FLURRIES MAY OCCUR N AND
NE OF THE TRIANGLE TOWARD THE VA BORDER (ROXBORO EAST TO ROANOKE
RAPIDS) BETWEEN 09-15Z WHERE DPVA IN THE PRESENCE OF STEEP MID-LEVEL
LAPSE RATES AND LINGERING LOW-LEVEL MOISTURE IN THE ICE NUCLEATION
ZONE MAY (BARELY) OVERCOME STRENGTHENING SUBSIDENCE ALOFT...THOUGH
NO MEASURABLE PRECIPITATION WOULD BE EXPECTED. 07Z RADAR DATA FROM
KFCX LENDS CREDENCE TO THIS POSSIBILITY.
THIS AFTERNOON THROUGH TONIGHT:
PRONOUNCED DRYING ALOFT (ESPECIALLY 8+ KFT AGL) WILL OCCUR
THROUGHOUT THE DAY AS THE UPPER LEVEL TROUGH AXIS PROGRESSES
OFFSHORE THE MID-ATLANTIC AND CAROLINA COAST. LOW-LEVEL MOISTURE
PROGGED TO ADVECT INTO THE REGION FROM THE NW UNDERNEATH THE
STRENGTHENING MID-LEVEL SUBSIDENCE INVERSION MAY ALLOW FOR SCATTERED
CLOUD COVER WITH BASES AT 5-7 KFT AGL TODAY. OTHERWISE...EXPECT
MOSTLY SUNNY SKIES. 1000-850 MB THICKNESSES AND H85 TEMPS SUGGEST
CHILLY TEMPS TODAY...RANGING FROM THE MID 30S N/NE TO UPPER 30S AND
LOWER 40S FAR S/SW. 25-35 KT FLOW NW FLOW IN THE MIXED LAYER
(STRONGEST THROUGH 18Z) WILL RESULT IN BREEZY CONDITIONS...
ESPECIALLY N/NE OF THE TRIANGLE. EXPECT SUSTAINED NW WINDS AT 10-20
MPH WITH GUSTS GENERALLY IN THE 20-30 MPH RANGE...THOUGH SPORADIC
HIGHER GUSTS UP TO 35 MPH WILL BE POSSIBLE. EXPECT WIND CHILL VALUES
IN THE TEENS (PRIMARILY NORTH OF HWY 64) THIS MORNING...AND
LINGERING IN THE 20S THIS AFTERNOON...ESPECIALLY IN THE NORTH. WITH
A COLD/DRY AIRMASS IN PLACE...CLEAR SKIES AND AND CALM WINDS TONIGHT
AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION FROM THE
SOUTHWEST... EXPECT EXCELLENT RADIATIONAL COOLING WITH CHILLY LOWS
RANGING FROM THE MID/UPPER TEENS IN RURAL/LOW-LYING AREAS TO LOWER
20S IN URBAN AREAS. -VINCENT
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
AS OF 300 AM SUNDAY...
AS THE COLD MODIFIED ARCTIC SURFACE HIGH SLIPS EAST AND OFFSHORE
MONDAY... THE RETURN FLOW WILL BRING A STRONG WARMING TREND BY
AFTERNOON. HOWEVER... THE AIR MASS WILL REMAIN DRY AND WITH THE
BREEZY WINDS (EVEN IF THEY ARE FROM THE SW) IT WILL STILL FEEL
RATHER CHILLY. HIGHS 50-55 EXPECTED WITH MOSTLY SUNNY SKIES.
INCREASING MID AND HIGH LEVEL MOISTURE WILL LEAD TO PARTLY CLOUDY
BECOMING MOSTLY CLOUDY SKIES MONDAY NIGHT. LOWS WILL BE MUCH MILDER
WITH LOWS IN THE UPPER 30S TO MID 40S.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 317 AM SUNDAY...
THE MAIN STORM TRACK WITH THE NEXT APPROACHING SYSTEM IS EXPECTED TO
BE FROM THE MIDWEST NE ACROSS THE GREAT LAKES TUE-TUE NIGHT. THE
TRAILING COLD FRONT IS EXPECTED TO PUSH EAST ACROSS OUR REGION
TUESDAY. INITIALLY... A STRONG AND MOIST FLOW FROM THE GULF WILL
ALLOW FOR SIGNIFICANT RAIN INTO THE TENNESSEE VALLEY INTO FAR
WESTERN NC INTO MONDAY NIGHT. HOWEVER... AS THE STORM MOVES OVER THE
GREAT LAKES... THE MEAN FLOW IS EXPECTED TO BECOME PROGRESSIVELY
MORE WESTERLY AS THE SYSTEM MOVES ACROSS THE APPALACHIANS TO THE
MID-ATLANTIC COAST TUESDAY AFTERNOON AND EVENING. THIS EFFECTIVELY
SHUTS DOWN THE GULF INFLOW AS THE COLD FRONT MOVES THROUGH CENTRAL
NC. WE WILL CONTINUE TO CARRY HIGH POPS BUT LOW QPF. MOST AREAS
SHOULD SEE LESS THAN 0.25 WITH EASTERN ZONES POSSIBLY LESS THAN
0.10. THE LIKELY POP WILL BE CONFINED TO TUESDAY... WITH RAPIDLY
DECREASING POP TUESDAY EVENING FROM WEST TO EAST AS THE COLD FRONT
REACHES THE COAST. HIGHS TUESDAY WILL BE HELD DOWN DUE TO THE CLOUDS
AND SHOWERS. EXPECT SOME 40S TO HOLD ON OVER THE PIEDMONT... WITH
50S SE. SKIES WILL BECOME PARTLY CLOUDY TUESDAY NIGHT WITH CAA
LEADING TO LOWS OF 30-35.
WED-THU... VERY COLD AND STRONG ARCTIC HIGH PRESSURE WILL AFFECT THE
UPPER MIDWEST AND GREAT LAKES. THIS HIGH PRESSURE IS FORECAST TO
BUILD SOUTH INTO NC THIS PERIOD. HOWEVER... THE CORE OF THE ARCTIC
AIR IS FORECAST TO REMAIN FROM AROUND NORTHERN VA NORTHWARD. YET...
THE FEED OF DRY AND COLD AIR WILL ALLOW TEMPS TO FALL BELOW NORMAL
WED NIGHT AND THURSDAY. MOSTLY CLEAR SKIES ARE EXPECTED WED-THU...
HIGHS WED SHOULD BE IN THE UPPER 40S TO MID 50S... COOLING INTO THE
MID 40S TO LOWER 50S THURSDAY. LOWS WED SHOULD BE 25-30.
BY FRIDAY... ANOTHER STORM SYSTEM IS EXPECTED TO FOLLOW THE SAME
GENERAL TRACK AS THE LAST SEVERAL STORMS... FROM THE PLAINS TO THE
GREAT LAKES. HOWEVER... THE LARGE COLD SURFACE HIGH SHOULD BE
LOCATED OVER NEW ENGLAND THU NIGHT... THEN SLOWLY DRIFT EAST BY
FRIDAY AND FRIDAY NIGHT. THE HIGH IS FORECAST TO BE MORE THAN STRONG
ENOUGH... AND IN MORE THAN ADEQUATE POSITION TO FAVOR A CLASSICAL TO
HYBRID CAD EVENT FOR FRI-FRI NIGHT AS THE PRECIPITATION ASSOCIATED
WITH THE STORM SYSTEM ARRIVES FROM THE WEST. FOR NOW... IT DOES
APPEAR TO BE WARM ENOUGH FOR RAIN... ALTHOUGH THIS WILL HAVE TO BE
WATCHED CLOSELY FOR FRIDAY. LOWS 30-35. HIGHS 38-48 NW TO SE.
THE FRONT SHOULD SETTLE SOUTH OF THE REGION OVER THE WEEKEND... WITH
ANOTHER POTENTIAL STORM WITH SIGNIFICANT PRECIPITATION OVER THE SE
INTO THE MID-ATLANTIC LATER IN THE WEEKEND. THE POTENTIAL STORM
TRACK FROM THE GULF TO THE SE STATES ALLOWS POTENTIAL FOR WINTERY
PRECIP INTO THE MID-ATLANTIC STATES... BUT THE QUESTION WILL BE THE
POSITION AND STRENGTH OF THE SURFACE HIGH THAT WILL FOLLOW THE
FRONT FRIDAY... AND HOW FAR SOUTH THE COLD AIR CAN REACH.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 120 AM SUNDAY...
24-HR TAF PERIOD:
VFR CONDITIONS WILL RULE THROUGH THE TAF PERIOD AS AN INTENSIFYING
LOW PRESSURE SYSTEM TRACKS FURTHER OFFSHORE INTO THE ATLANTIC. THE
PRIMARY AVIATION CONCERN WILL BE BREEZY WNW/NW WINDS TODAY...
SUSTAINED AT 15 KT WITH GUSTS GENERALLY TO 25 KT...THOUGH A PERIOD
OF STRONGER WINDS SUSTAINED AT 20 KT WITH GUSTS UP TO 30 KT WILL BE
POSSIBLE...PRIMARILY BETWEEN 12-18Z...ESPECIALLY AT THE RWI
TERMINAL. WINDS WILL DECREASE TO 5-10 KT AFTER 21Z...BECOMING LIGHT
AND VARIABLE AFTER 00Z.
LOOKING AHEAD:
VFR CONDITIONS WILL RULE THROUGH MONDAY IN ASSOCIATION WITH DRY HIGH
PRESSURE. HIGH PRESSURE WILL MOVE OFFSHORE MONDAY NIGHT AS A COLD
FRONT APPROACHES THE MOUNTAINS FROM THE WEST. EXPECT DETERIORATING
CONDITIONS WITH MVFR/IFR CEILINGS DEVELOPING IN ASSOC/W AN
INCREASINGLY MOIST RETURN FLOW BETWEEN 06-12Z TUE AND INCREASING
CHANCES FOR RAIN FROM WEST-EAST BETWEEN 12-18Z TUE. A PERIOD OF
SOUTHWESTERLY LOW LEVEL WIND SHEAR WILL BE POSSIBLE BETWEEN 06Z TUE
MORNING AND 18Z TUE AFTERNOON AS A 40-45 KT LLJ DEVELOPS AS LOW DOWN
AS 1500-2000 FT AGL. EXPECT RAPID CLEARING AND A RETURN TO VFR
CONDITIONS IN THE WAKE OF THE COLD FRONTAL PASSAGE LATE TUE INTO TUE
NIGHT. VFR CONDITIONS WILL PREVAIL THROUGH THURSDAY AS DRY HIGH
PRESSURE BUILDS OVER THE CAROLINAS. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 10 AM EST SUNDAY FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
258 AM EST SUN FEB 17 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL BUILD TOWARD THE CAROLINAS FROM THE
SOUTHWEST TODAY AS A RAPIDLY INTENSIFYING LOW PRESSURE SYSTEM
OFFSHORE THE MID ATLANTIC COAST TRACKS NORTHEAST TOWARD THE CANADIAN
MARITIMES. HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT BEFORE
MOVING OFFSHORE LATE MONDAY INTO MONDAY NIGHT AS A COLD FRONT
APPROACHES THE MOUNTAINS FROM THE WEST.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 255 AM SUNDAY...
THIS MORNING:
A LINGERING NNW-SSE ORIENTED BAND OF SNOW OVER THE COASTAL PLAIN
WILL CONTINUE TO WEAKEN...DISSIPATING BY 300-330 AM AS THE UPPER
LEVEL TROUGH AXIS PROGRESSES EAST OF CENTRAL NC AND STRENGTHENING
SYNOPTIC SUBSIDENCE RESULTS IN RAPID DRYING ALOFT. AS MUCH AS 1.0 TO
1.5 INCHES OF SNOW ACCUMULATION OCCURRED IN ASSOCIATION WITH THIS
BAND OVER GRANVILLE...VANCE...FRANKLIN...EASTERN WAKE... JOHNSTON...
WAYNE AND EASTERN SAMPSON COUNTIES BETWEEN 900 PM SATURDAY EVENING
AND 200 AM THIS MORNING. EXPECT DANGEROUS ROAD CONDITIONS ALONG THE
INTERSTATE 85 CORRIDOR FROM DURHAM NORTH TO THE VIRGINIA
BORDER...ALONG THE INTERSTATE 40 CORRIDOR FROM RALEIGH EAST TO
BENSON-HOBBTON-WARSAW...AND ALONG THE INTERSTATE 95 CORRIDOR FROM
BENSON NORTH TO ROANOKE RAPIDS. HAVE HIGHLIGHTED THESE AREAS IN THE
WINTER WEATHER ADVISORY THAT REMAINS IN EFFECT UNTIL 10 AM THIS
MORNING...WHEN TEMPERATURES ARE EXPECTED TO RISE ABOVE FREEZING.
ADDITIONAL SHORTWAVE ENERGY APPROACHING WEST VIRGINIA AT 07Z IS
PROGGED TO TRACK SOUTHEAST THROUGH SOUTHERN VA AND NORTHEAST NC
BETWEEN 12-15Z THIS MORNING...IN THE PRESENCE OF LINGERING LOW-LEVEL
MOISTURE AND STEEP MID-LEVEL LAPSE RATES (7-7.5 C/KM) OVER THE N/NE
OF THE TRIANGLE INTO CENTRAL/SOUTHEAST VA (PER 00Z RAOB AND THE
LATEST RAP MODEL DATA). IT IS POSSIBLE THAT FLURRIES MAY OCCUR N AND
NE OF THE TRIANGLE TOWARD THE VA BORDER (ROXBORO EAST TO ROANOKE
RAPIDS) BETWEEN 09-15Z WHERE DPVA IN THE PRESENCE OF STEEP MID-LEVEL
LAPSE RATES AND LINGERING LOW-LEVEL MOISTURE IN THE ICE NUCLEATION
ZONE MAY (BARELY) OVERCOME STRENGTHENING SUBSIDENCE ALOFT...THOUGH
NO MEASURABLE PRECIPITATION WOULD BE EXPECTED. 07Z RADAR DATA FROM
KFCX LENDS CREDENCE TO THIS POSSIBILITY.
THIS AFTERNOON THROUGH TONIGHT:
PRONOUNCED DRYING ALOFT (ESPECIALLY 8+ KFT AGL) WILL OCCUR
THROUGHOUT THE DAY AS THE UPPER LEVEL TROUGH AXIS PROGRESSES
OFFSHORE THE MID-ATLANTIC AND CAROLINA COAST. LOW-LEVEL MOISTURE
PROGGED TO ADVECT INTO THE REGION FROM THE NW UNDERNEATH THE
STRENGTHENING MID-LEVEL SUBSIDENCE INVERSION MAY ALLOW FOR SCATTERED
CLOUD COVER WITH BASES AT 5-7 KFT AGL TODAY. OTHERWISE...EXPECT
MOSTLY SUNNY SKIES. 1000-850 MB THICKNESSES AND H85 TEMPS SUGGEST
CHILLY TEMPS TODAY...RANGING FROM THE MID 30S N/NE TO UPPER 30S AND
LOWER 40S FAR S/SW. 25-35 KT FLOW NW FLOW IN THE MIXED LAYER
(STRONGEST THROUGH 18Z) WILL RESULT IN BREEZY CONDITIONS...
ESPECIALLY N/NE OF THE TRIANGLE. EXPECT SUSTAINED NW WINDS AT 10-20
MPH WITH GUSTS GENERALLY IN THE 20-30 MPH RANGE...THOUGH SPORADIC
HIGHER GUSTS UP TO 35 MPH WILL BE POSSIBLE. EXPECT WIND CHILL VALUES
IN THE TEENS (PRIMARILY NORTH OF HWY 64) THIS MORNING...AND
LINGERING IN THE 20S THIS AFTERNOON...ESPECIALLY IN THE NORTH. WITH
A COLD/DRY AIRMASS IN PLACE...CLEAR SKIES AND AND CALM WINDS TONIGHT
AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION FROM THE
SOUTHWEST... EXPECT EXCELLENT RADIATIONAL COOLING WITH CHILLY LOWS
RANGING FROM THE MID/UPPER TEENS IN RURAL/LOW-LYING AREAS TO LOWER
20S IN URBAN AREAS. -VINCENT
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
AS OF 240 PM SATURDAY...
TEMPS WILL BEGIN TO MODERATE ON MONDAY AS SHORTWAVE RIDGING BUILDS
EAST AND THE HIGH SLIPS OFFSHORE RESULTING IN A RETURN TO SOUTHERLY
FLOW. HIGHS IN THE UPPER 40S TO LOW/MID 50S ARE EXPECTED ON
MONDAY...WITH OVERNIGHT LOWS GENERALLY IN THE LOW/MID 30S.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 240 PM SATURDAY...
SOUTHERLY FLOW WILL INCREASE AHEAD OF AN APPROACHING FRONT ON
TUESDAY AND THIS WILL ALLOW TEMPS TO WARM EVEN MORE...WITH HIGHS
POSSIBLY APPROACHING 60 DEGREES ACROSS THE SOUTHEAST. HOWEVER...
FURTHER TO THE NORTH AND WEST...INCREASING CLOUDS/PRECIP CHANCES
EARLIER IN THE DAY SHOULD HOLD TEMPS IN THE LOW/MID 50S (MAYBE EVEN
SOME UPPER 40S). THE FRONT IS EXPECTED TO CROSS THE REGION THROUGH
TUESDAY EVENING AND BRING WITH IT A GOOD CHANCE OF SHOWERS. BEHIND
THE FRONT...THERE SHOULD BE ENOUGH CLEARING TUESDAY NIGHT WHERE
TEMPS WOULD DROP INTO THE LOW/MID 30S.
SURFACE HIGH PRESSURE AND SHORTWAVE RIDGING WILL THEN DOMINATE THE
WEATHER ACROSS CENTRAL NC THROUGH THURSDAY. THIS WILL RESULT IN FAIR
WEATHER CONDITIONS AND NEAR NORMAL TEMPS. THE NEXT SYSTEM LOOKS TO
APPROACH THE AREA LATE THURSDAY NIGHT INTO FRIDAY. ALSO...THERE
CONTINUES TO BE INDICATIONS OF A CAD EVENT SETTING UP ACROSS THE
REGION AND THIS WILL HAVE TO BE MONITORED FOR POTENTIAL P-TYPE
ISSUES (ESPECIALLY AT THE ONSET OF ANY PRECIP) AND COOLER THAN
EXPECTED TEMPS...ESPECIALLY ACROSS THE NORTHWEST. FOR NOW...WILL
SHOW RAIN CHANCES INCREASING FROM WEST TO EAST DURING THE DAY ON
FRIDAY...WITH HIGHS RANGING FROM THE 40S ACROSS THE NORTHWEST TO
UPPER 50S (MAYBE NEAR 60 DEGREES) ACROSS THE EXTREME SOUTHEAST.
THERE IS UNCERTAINTY WITH RESPECT TO HOW QUICKLY THIS SYSTEM WILL
PROGRESS ACROSS THE REGION...WITH THE ECMWF MAINTAINING PRECIP
CHANCES THROUGH SATURDAY AS THE FRONT STALLS NEAR THE REGION. FOR
NOW WILL SHOW PRECIP ENDING ON SATURDAY...BUT CLOUDY CONDITIONS
PERSISTING.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 120 AM SUNDAY...
24-HR TAF PERIOD:
VFR CONDITIONS WILL RULE THROUGH THE TAF PERIOD AS AN INTENSIFYING
LOW PRESSURE SYSTEM TRACKS FURTHER OFFSHORE INTO THE ATLANTIC. THE
PRIMARY AVIATION CONCERN WILL BE BREEZY WNW/NW WINDS TODAY...
SUSTAINED AT 15 KT WITH GUSTS GENERALLY TO 25 KT...THOUGH A PERIOD
OF STRONGER WINDS SUSTAINED AT 20 KT WITH GUSTS UP TO 30 KT WILL BE
POSSIBLE...PRIMARILY BETWEEN 12-18Z...ESPECIALLY AT THE RWI
TERMINAL. WINDS WILL DECREASE TO 5-10 KT AFTER 21Z...BECOMING LIGHT
AND VARIABLE AFTER 00Z.
LOOKING AHEAD:
VFR CONDITIONS WILL RULE THROUGH MONDAY IN ASSOCIATION WITH DRY HIGH
PRESSURE. HIGH PRESSURE WILL MOVE OFFSHORE MONDAY NIGHT AS A COLD
FRONT APPROACHES THE MOUNTAINS FROM THE WEST. EXPECT DETERIORATING
CONDITIONS WITH MVFR/IFR CEILINGS DEVELOPING IN ASSOC/W AN
INCREASINGLY MOIST RETURN FLOW BETWEEN 06-12Z TUE AND INCREASING
CHANCES FOR RAIN FROM WEST-EAST BETWEEN 12-18Z TUE. A PERIOD OF
SOUTHWESTERLY LOW LEVEL WIND SHEAR WILL BE POSSIBLE BETWEEN 06Z TUE
MORNING AND 18Z TUE AFTERNOON AS A 40-45 KT LLJ DEVELOPS AS LOW DOWN
AS 1500-2000 FT AGL. EXPECT RAPID CLEARING AND A RETURN TO VFR
CONDITIONS IN THE WAKE OF THE COLD FRONTAL PASSAGE LATE TUE INTO TUE
NIGHT. VFR CONDITIONS WILL PREVAIL THROUGH THURSDAY AS DRY HIGH
PRESSURE BUILDS OVER THE CAROLINAS. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 10 AM EST SUNDAY FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...KRR
LONG TERM...KRR
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
257 AM EST SUN FEB 17 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL BUILD TOWARD THE CAROLINAS FROM THE
SOUTHWEST TODAY AS A RAPIDLY INTENSIFYING LOW PRESSURE SYSTEM
OFFSHORE THE MID ATLANTIC COAST TRACKS NORTHEAST TOWARD THE CANADIAN
MARITIMES. HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT BEFORE
MOVING OFFSHORE LATE MONDAY INTO MONDAY NIGHT AS A COLD FRONT
APPROACHES THE MOUNTAINS FROM THE WEST.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 255 AM SUNDAY...
THIS MORNING:
A LINGERING NNW-SSE ORIENTED BAND OF SNOW OVER THE COASTAL PLAIN
WILL CONTINUE TO WEAKEN...DISSIPATING BY 300-330 AM AS THE UPPER
LEVEL TROUGH AXIS PROGRESSES EAST OF CENTRAL NC AND STRENGTHENING
SYNOPTIC SUBSIDENCE RESULTS IN RAPID DRYING ALOFT. AS MUCH AS 1.0 TO
1.5 INCHES OF SNOW ACCUMULATION OCCURRED IN ASSOCIATION WITH THIS
BAND OVER GRANVILLE...VANCE...FRANKLIN...EASTERN WAKE... JOHNSTON...
WAYNE AND EASTERN SAMPSON COUNTIES BETWEEN 900 PM SATURDAY EVENING
AND 200 AM THIS MORNING. EXPECT DANGEROUS ROAD CONDITIONS ALONG THE
INTERSTATE 85 CORRIDOR FROM DURHAM NORTH TO THE VIRGINIA
BORDER...ALONG THE INTERSTATE 40 CORRIDOR FROM RALEIGH EAST TO
BENSON-HOBBTON-WARSAW...AND ALONG THE INTERSTATE 95 CORRIDOR FROM
BENSON NORTH TO ROANOKE RAPIDS. HAVE HIGHLIGHTED THESE AREAS IN THE
WINTER WEATHER ADVISORY THAT REMAINS IN EFFECT UNTIL 10 AM THIS
MORNING...WHEN TEMPERATURES ARE EXPECTED TO RISE ABOVE FREEZING.
ADDITIONAL SHORTWAVE ENERGY APPROACHING WEST VIRGINIA AT 07Z IS
PROGGED TO TRACK SOUTHEAST THROUGH SOUTHERN VA AND NORTHEAST NC
BETWEEN 12-15Z THIS MORNING...IN THE PRESENCE OF LINGERING LOW-LEVEL
MOISTURE AND STEEP MID-LEVEL LAPSE RATES (7-7.5 C/KM) OVER THE N/NE
OF THE TRIANGLE INTO CENTRAL/SOUTHEAST VA (PER 00Z RAOB AND THE
LATEST RAP MODEL DATA). IT IS POSSIBLE THAT FLURRIES MAY OCCUR N AND
NE OF THE TRIANGLE TOWARD THE VA BORDER (ROXBORO EAST TO ROANOKE
RAPIDS) BETWEEN 09-15Z WHERE DPVA IN THE PRESENCE OF STEEP MID-LEVEL
LAPSE RATES AND LINGERING LOW-LEVEL MOISTURE IN THE ICE NUCLEATION
ZONE MAY (BARELY) OVERCOME STRENGTHENING SUBSIDENCE ALOFT...THOUGH
NO MEASURABLE PRECIPITATION WOULD BE EXPECTED. 07Z RADAR DATA FROM
KFCX LENDS CREDENCE TO THIS POSSIBILITY.
THIS AFTERNOON THROUGH TONIGHT:
PRONOUNCED DRYING ALOFT (ESPECIALLY 8+ KFT AGL) WILL OCCUR
THROUGHOUT THE DAY AS THE UPPER LEVEL TROUGH AXIS PROGRESSES
OFFSHORE THE MID-ATLANTIC AND CAROLINA COAST. LOW-LEVEL MOISTURE
PROGGED TO ADVECT INTO THE REGION FROM THE NW UNDERNEATH THE
STRENGTHENING MID-LEVEL SUBSIDENCE INVERSION MAY ALLOW FOR SCATTERED
CLOUD COVER WITH BASES AT 5-7 KFT AGL TODAY. OTHERWISE...EXPECT
MOSTLY SUNNY SKIES. 1000-850 MB THICKNESSES AND H85 TEMPS SUGGEST
CHILLY TEMPS TODAY...RANGING FROM THE MID 30S N/NE TO UPPER 30S AND
LOWER 40S FAR S/SW. 25-35 KT FLOW NW FLOW IN THE MIXED LAYER
(STRONGEST THROUGH 18Z) WILL RESULT IN BREEZY CONDITIONS...
ESPECIALLY N/NE OF THE TRIANGLE. EXPECT SUSTAINED NW WINDS AT 10-20
MPH WITH GUSTS GENERALLY IN THE 20-30 MPH RANGE...THOUGH SPORADIC
HIGHER GUSTS UP TO 35 MPH WILL BE POSSIBLE. EXPECT WIND CHILL VALUES
IN THE TEENS (PRIMARILY NORTH OF HWY 64) THIS MORNING...AND
LINGERING IN THE 20S THIS AFTERNOON...ESPECIALLY IN THE NORTH. WITH
A COLD/DRY AIRMASS IN PLACE...CLEAR SKIES AND AND CALM WINDS TONIGHT
AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION FROM THE
SOUTHWEST... EXPECT EXCELLENT RADIATIONAL COOLING WITH CHILLY LOWS
RANGING FROM THE MID/UPPER TEENS IN RURAL/LOW-LYING AREAS TO LOWER
20S IN URBAN AREAS. -VINCENT
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 240 PM SATURDAY...
THE SHORT TERM PERIOD WILL START WITH A COLD UPPER TROUGH OVER THE
EASTERN US...WHILE AT THE SURFACE...HIGH PRESSURE WILL GRADUALLY
BUILD IN BEHIND THE DEPARTING LOW THAT WILL BE TRACKING UP THE EAST
COAST. HIGHS ON SUNDAY WILL BE RATHER CHILLY...WITH TEMPS ONLY
RISING INTO THE MID/UPPER 30S TO LOWER 40S. IN ADDITION...WINDS WILL
BE QUITE BREEZY AS THE PRESSURE GRADIENT REMAINS TIGHT OVER THE AREA
BETWEEN THE DEPARTING AND DEEPENING LOW AND THE HIGH BUILDING IN.
THE PRESSURE GRADIENT WILL RELAX SUNDAY NIGHT AS THE HIGH BUILDS
NEARLY OVERHEAD AND GOOD RADIATIONAL COOLING CONDITIONS WILL SET
UP...ALLOWING OVERNIGHT LOWS TO FALL INTO THE LOW TO MID 20S. TEMPS
WILL BEGIN TO MODERATE ON MONDAY AS SHORTWAVE RIDGING BUILDS EAST
AND THE HIGH SLIPS OFFSHORE RESULTING IN A RETURN TO SOUTHERLY FLOW.
HIGHS IN THE UPPER 40S TO LOW/MID 50S ARE EXPECTED ON MONDAY...WITH
OVERNIGHT LOWS GENERALLY IN THE LOW/MID 30S.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 240 PM SATURDAY...
SOUTHERLY FLOW WILL INCREASE AHEAD OF AN APPROACHING FRONT ON
TUESDAY AND THIS WILL ALLOW TEMPS TO WARM EVEN MORE...WITH HIGHS
POSSIBLY APPROACHING 60 DEGREES ACROSS THE SOUTHEAST. HOWEVER...
FURTHER TO THE NORTH AND WEST...INCREASING CLOUDS/PRECIP CHANCES
EARLIER IN THE DAY SHOULD HOLD TEMPS IN THE LOW/MID 50S (MAYBE EVEN
SOME UPPER 40S). THE FRONT IS EXPECTED TO CROSS THE REGION THROUGH
TUESDAY EVENING AND BRING WITH IT A GOOD CHANCE OF SHOWERS. BEHIND
THE FRONT...THERE SHOULD BE ENOUGH CLEARING TUESDAY NIGHT WHERE
TEMPS WOULD DROP INTO THE LOW/MID 30S.
SURFACE HIGH PRESSURE AND SHORTWAVE RIDGING WILL THEN DOMINATE THE
WEATHER ACROSS CENTRAL NC THROUGH THURSDAY. THIS WILL RESULT IN FAIR
WEATHER CONDITIONS AND NEAR NORMAL TEMPS. THE NEXT SYSTEM LOOKS TO
APPROACH THE AREA LATE THURSDAY NIGHT INTO FRIDAY. ALSO...THERE
CONTINUES TO BE INDICATIONS OF A CAD EVENT SETTING UP ACROSS THE
REGION AND THIS WILL HAVE TO BE MONITORED FOR POTENTIAL P-TYPE
ISSUES (ESPECIALLY AT THE ONSET OF ANY PRECIP) AND COOLER THAN
EXPECTED TEMPS...ESPECIALLY ACROSS THE NORTHWEST. FOR NOW...WILL
SHOW RAIN CHANCES INCREASING FROM WEST TO EAST DURING THE DAY ON
FRIDAY...WITH HIGHS RANGING FROM THE 40S ACROSS THE NORTHWEST TO
UPPER 50S (MAYBE NEAR 60 DEGREES) ACROSS THE EXTREME SOUTHEAST.
THERE IS UNCERTAINTY WITH RESPECT TO HOW QUICKLY THIS SYSTEM WILL
PROGRESS ACROSS THE REGION...WITH THE ECMWF MAINTAINING PRECIP
CHANCES THROUGH SATURDAY AS THE FRONT STALLS NEAR THE REGION. FOR
NOW WILL SHOW PRECIP ENDING ON SATURDAY...BUT CLOUDY CONDITIONS
PERSISTING.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 120 AM SUNDAY...
24-HR TAF PERIOD:
VFR CONDITIONS WILL RULE THROUGH THE TAF PERIOD AS AN INTENSIFYING
LOW PRESSURE SYSTEM TRACKS FURTHER OFFSHORE INTO THE ATLANTIC. THE
PRIMARY AVIATION CONCERN WILL BE BREEZY WNW/NW WINDS TODAY...
SUSTAINED AT 15 KT WITH GUSTS GENERALLY TO 25 KT...THOUGH A PERIOD
OF STRONGER WINDS SUSTAINED AT 20 KT WITH GUSTS UP TO 30 KT WILL BE
POSSIBLE...PRIMARILY BETWEEN 12-18Z...ESPECIALLY AT THE RWI
TERMINAL. WINDS WILL DECREASE TO 5-10 KT AFTER 21Z...BECOMING LIGHT
AND VARIABLE AFTER 00Z.
LOOKING AHEAD:
VFR CONDITIONS WILL RULE THROUGH MONDAY IN ASSOCIATION WITH DRY HIGH
PRESSURE. HIGH PRESSURE WILL MOVE OFFSHORE MONDAY NIGHT AS A COLD
FRONT APPROACHES THE MOUNTAINS FROM THE WEST. EXPECT DETERIORATING
CONDITIONS WITH MVFR/IFR CEILINGS DEVELOPING IN ASSOC/W AN
INCREASINGLY MOIST RETURN FLOW BETWEEN 06-12Z TUE AND INCREASING
CHANCES FOR RAIN FROM WEST-EAST BETWEEN 12-18Z TUE. A PERIOD OF
SOUTHWESTERLY LOW LEVEL WIND SHEAR WILL BE POSSIBLE BETWEEN 06Z TUE
MORNING AND 18Z TUE AFTERNOON AS A 40-45 KT LLJ DEVELOPS AS LOW DOWN
AS 1500-2000 FT AGL. EXPECT RAPID CLEARING AND A RETURN TO VFR
CONDITIONS IN THE WAKE OF THE COLD FRONTAL PASSAGE LATE TUE INTO TUE
NIGHT. VFR CONDITIONS WILL PREVAIL THROUGH THURSDAY AS DRY HIGH
PRESSURE BUILDS OVER THE CAROLINAS. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 10 AM EST SUNDAY FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...KRR
LONG TERM...KRR
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
128 AM EST SUN FEB 17 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL BUILD TOWARD THE CAROLINAS FROM THE
SOUTHWEST TODAY AS A RAPIDLY INTENSIFYING LOW PRESSURE SYSTEM
OFFSHORE THE MID ATLANTIC COAST TRACKS NORTHEAST TOWARD THE CANADIAN
MARITIMES. HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT BEFORE
MOVING OFFSHORE LATE MONDAY INTO MONDAY NIGHT AS A COLD FRONT
APPROACHES THE MOUNTAINS FROM THE WEST.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 955 PM SATURDAY...
INTERESTING SNOW EVENT HERE FOR CENTRAL NC WITH WIDELY VARYING
TOTALS RANGING FROM ALMOST NOTHING (MELTED AS IT FELL) TO ABOUT TWO
AND A HALF INCHES. RAPID CLASSIC CYCLOGENESIS IS CURRENTLY TAKING
PLACE OFF THE NC COAST... NOTED WELL IN IR AND WATER VAPOR IMAGERY
BY THE DISTINCT BAROCLINIC LEAF STRUCTURE AND WITH A VERY STRONG
(170+ KT) UPPER JET CORE OFF THE COAST... AND BY THE INCREASE IN
LIGHTNING STRIKES EAST OF HATTERAS. WE STILL HAVE FOCUSED AREAS OF
SNOW... ONE OVER NORTHEAST SC ASSOCIATED WITH INTENSE DVPA
(OCCURRING WITH 500 MB VORTICITY MAX PASSAGE) AND UPRIGHT
INSTABILITY... WHILE ANOTHER BAND OF SNOW ROTATES ACROSS THE
NORTHEAST FORECAST AREA ASSOCIATED WITH A MID LEVEL DEFORMATION
BAND. THE FORMER FEATURE AND ITS VIGOROUS LIFT HAS LARGELY HELD
SOUTH OF THE NC/SC BORDER AS WAS SUGGESTED BY RECENT HRRR RUNS...
AND WILL CONTINUE TO MOVE ESE AWAY FROM CENTRAL NC. THE LATTER
FEATURE IS FORECAST TO WEAKEN AND SLIDE EASTWARD OVER THE NEXT FEW
HOURS... ALTHOUGH IT MAY DROP ANOTHER QUICK DUSTING TO ISOLATED HALF
INCH AMOUNTS IN AREAS NORTH AND EAST OF RALEIGH. SURFACE FLOW HAS
BECOME NORTHWESTERLY AND CYCLONIC OVER CENTRAL NC AND DOWNSLOPE
DRYING ALONG WITH INCREASING SUBSIDENCE BEHIND THE DEPARTING 850-700
MB TROUGH IS HELPING TO SCOUR OUT CLOUDS WEST TO EAST. THIS TREND
SHOULD CONTINUE WITH THE REMAINING LIGHT SNOW DIMINISHING THROUGH
08Z... ENDING LAST IN AREAS EAST OF RWI/GSB. THE INFLUX OF VERY DRY
AIR HAS BEEN IMPRESSIVE WITH DEW POINTS ALREADY HAVING DROPPED FROM
THE LOW 30S INTO THE LOW-MID TEENS IN THE TRIAD... AND THIS TREND
TOO SHOULD PERSIST INTO THE OVERNIGHT HOURS... AS THE DRY AIR
SPREADS EASTWARD WHILE TEMPERATURES DROP INTO THE 20S. WHILE 4 INCH
SOIL TEMPS ARE STILL SITTING IN THE LOW-MID 40S... ROAD SURFACES ARE
MARKEDLY COOLER... ESPECIALLY BRIDGES AND OVERPASSES WHICH ARE
LIKELY TO SEE SOME REFREEZING OF THE RESIDUAL WATER ON ROADS
OVERNIGHT. AS SUCH... THE EARLIER WINTER WEATHER ADVISORY FOR SNOW
HAS BEEN CANCELED EARLY... AND ANOTHER ADVISORY FOR BLACK ICE WILL
BE ISSUED FROM MIDNIGHT UNTIL 11 AM SUNDAY MORNING... WHEN TEMPS ARE
EXPECTED TO SURPASS THE FREEZING MARK OVER MUCH OF THE AREA. LOWS
TONIGHT 23-28. -GIH
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 240 PM SATURDAY...
THE SHORT TERM PERIOD WILL START WITH A COLD UPPER TROUGH OVER THE
EASTERN US...WHILE AT THE SURFACE...HIGH PRESSURE WILL GRADUALLY
BUILD IN BEHIND THE DEPARTING LOW THAT WILL BE TRACKING UP THE EAST
COAST. HIGHS ON SUNDAY WILL BE RATHER CHILLY...WITH TEMPS ONLY
RISING INTO THE MID/UPPER 30S TO LOWER 40S. IN ADDITION...WINDS WILL
BE QUITE BREEZY AS THE PRESSURE GRADIENT REMAINS TIGHT OVER THE AREA
BETWEEN THE DEPARTING AND DEEPENING LOW AND THE HIGH BUILDING IN.
THE PRESSURE GRADIENT WILL RELAX SUNDAY NIGHT AS THE HIGH BUILDS
NEARLY OVERHEAD AND GOOD RADIATIONAL COOLING CONDITIONS WILL SET
UP...ALLOWING OVERNIGHT LOWS TO FALL INTO THE LOW TO MID 20S. TEMPS
WILL BEGIN TO MODERATE ON MONDAY AS SHORTWAVE RIDGING BUILDS EAST
AND THE HIGH SLIPS OFFSHORE RESULTING IN A RETURN TO SOUTHERLY FLOW.
HIGHS IN THE UPPER 40S TO LOW/MID 50S ARE EXPECTED ON MONDAY...WITH
OVERNIGHT LOWS GENERALLY IN THE LOW/MID 30S.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 240 PM SATURDAY...
SOUTHERLY FLOW WILL INCREASE AHEAD OF AN APPROACHING FRONT ON
TUESDAY AND THIS WILL ALLOW TEMPS TO WARM EVEN MORE...WITH HIGHS
POSSIBLY APPROACHING 60 DEGREES ACROSS THE SOUTHEAST. HOWEVER...
FURTHER TO THE NORTH AND WEST...INCREASING CLOUDS/PRECIP CHANCES
EARLIER IN THE DAY SHOULD HOLD TEMPS IN THE LOW/MID 50S (MAYBE EVEN
SOME UPPER 40S). THE FRONT IS EXPECTED TO CROSS THE REGION THROUGH
TUESDAY EVENING AND BRING WITH IT A GOOD CHANCE OF SHOWERS. BEHIND
THE FRONT...THERE SHOULD BE ENOUGH CLEARING TUESDAY NIGHT WHERE
TEMPS WOULD DROP INTO THE LOW/MID 30S.
SURFACE HIGH PRESSURE AND SHORTWAVE RIDGING WILL THEN DOMINATE THE
WEATHER ACROSS CENTRAL NC THROUGH THURSDAY. THIS WILL RESULT IN FAIR
WEATHER CONDITIONS AND NEAR NORMAL TEMPS. THE NEXT SYSTEM LOOKS TO
APPROACH THE AREA LATE THURSDAY NIGHT INTO FRIDAY. ALSO...THERE
CONTINUES TO BE INDICATIONS OF A CAD EVENT SETTING UP ACROSS THE
REGION AND THIS WILL HAVE TO BE MONITORED FOR POTENTIAL P-TYPE
ISSUES (ESPECIALLY AT THE ONSET OF ANY PRECIP) AND COOLER THAN
EXPECTED TEMPS...ESPECIALLY ACROSS THE NORTHWEST. FOR NOW...WILL
SHOW RAIN CHANCES INCREASING FROM WEST TO EAST DURING THE DAY ON
FRIDAY...WITH HIGHS RANGING FROM THE 40S ACROSS THE NORTHWEST TO
UPPER 50S (MAYBE NEAR 60 DEGREES) ACROSS THE EXTREME SOUTHEAST.
THERE IS UNCERTAINTY WITH RESPECT TO HOW QUICKLY THIS SYSTEM WILL
PROGRESS ACROSS THE REGION...WITH THE ECMWF MAINTAINING PRECIP
CHANCES THROUGH SATURDAY AS THE FRONT STALLS NEAR THE REGION. FOR
NOW WILL SHOW PRECIP ENDING ON SATURDAY...BUT CLOUDY CONDITIONS
PERSISTING.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 120 AM SUNDAY...
24-HR TAF PERIOD:
VFR CONDITIONS WILL RULE THROUGH THE TAF PERIOD AS AN INTENSIFYING
LOW PRESSURE SYSTEM TRACKS FURTHER OFFSHORE INTO THE ATLANTIC. THE
PRIMARY AVIATION CONCERN WILL BE BREEZY WNW/NW WINDS TODAY...
SUSTAINED AT 15 KT WITH GUSTS GENERALLY TO 25 KT...THOUGH A PERIOD
OF STRONGER WINDS SUSTAINED AT 20 KT WITH GUSTS UP TO 30 KT WILL BE
POSSIBLE...PRIMARILY BETWEEN 12-18Z...ESPECIALLY AT THE RWI
TERMINAL. WINDS WILL DECREASE TO 5-10 KT AFTER 21Z...BECOMING LIGHT
AND VARIABLE AFTER 00Z.
LOOKING AHEAD:
VFR CONDITIONS WILL RULE THROUGH MONDAY IN ASSOCIATION WITH DRY HIGH
PRESSURE. HIGH PRESSURE WILL MOVE OFFSHORE MONDAY NIGHT AS A COLD
FRONT APPROACHES THE MOUNTAINS FROM THE WEST. EXPECT DETERIORATING
CONDITIONS WITH MVFR/IFR CEILINGS DEVELOPING IN ASSOC/W AN
INCREASINGLY MOIST RETURN FLOW BETWEEN 06-12Z TUE AND INCREASING
CHANCES FOR RAIN FROM WEST-EAST BETWEEN 12-18Z TUE. A PERIOD OF
SOUTHWESTERLY LOW LEVEL WIND SHEAR WILL BE POSSIBLE BETWEEN 06Z TUE
MORNING AND 18Z TUE AFTERNOON AS A 40-45 KT LLJ DEVELOPS AS LOW DOWN
AS 1500-2000 FT AGL. EXPECT RAPID CLEARING AND A RETURN TO VFR
CONDITIONS IN THE WAKE OF THE COLD FRONTAL PASSAGE LATE TUE INTO TUE
NIGHT. VFR CONDITIONS WILL PREVAIL THROUGH THURSDAY AS DRY HIGH
PRESSURE BUILDS OVER THE CAROLINAS. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 10 AM EST SUNDAY FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...HARTFIELD
SHORT TERM...KRR
LONG TERM...KRR
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
319 PM CST SUN FEB 17 2013
.SHORT TERM...
MAIN CHALLENGE FOR THIS PORTION OF THE FORECAST WILL BE HOW TO
HANDLE HEADLINES WITH THE LOW CROSSING THE AREA TONIGHT INTO
MONDAY. MODELS STILL HAVE SOME SUBTLE DIFFERENCES IN REGARD TO
SNOWFALL AMOUNTS TONIGHT BUT GUSTY WIND LOOKS LIKE A SURE BET.
TONIGHT...SFC LOW IS CURRENTLY OVER NORTH CENTRAL/NORTHEAST ND
WITH VERY MILD AIR ASSOCIATED WITH IT. GETTING A SOUTHWEST SFC
COMPONENT TO THE WINDS OVER THE FAR WESTERN FA WHERE TEMPS HAVE
CLIMBED INTO THE LOW TO MID 30S. OTHER AREAS WILL PROBABLY SEE
SOME LATE AFTERNOON OR EARLY EVENING RISE BEFORE FALLING LATE.
STIFF SOUTH WINDS ARE CAUSING SOME DRIFTING SNOW ACROSS SOME ROADS
AND WITH THE MILD ROAD TEMPS ARE MELTING AND THEN REFREEZING.
OTHERWISE THE WARM TEMPS SHOULD BE GIVING A BIT OF A CRUST TO THE
SNOW IN THOSE AREAS ABOVE 32F. RADAR STILL SHOWING SOME ECHOES
ACROSS THE EAST BUT ONLY KBDE/KFGN ARE STILL REPORTING SOME LIGHT
SNOW. NOT REALLY EXPECTING SNOW ACROSS THE SOUTHERN FA PRIOR TO
MIDNIGHT. THERE SHOULD BE IN THE NORTH THOUGH WITH BEST CHANCES
ALONG THE CANADIAN BORDER. NEW 18Z NAM HAS COME IN SHOWING A BAND
DEVELOPING ACROSS THE CENTRAL RED RIVER VALLEY IN THE EVENING
WHICH LOOKS A LITTLE ODD. THE 12Z GFS SHOWS A BAND DEVELOPING
ACROSS CENTRAL ND AND LIFTING INTO THE NORTHERN RED RIVER VALLEY.
ECMWF SEEMS PRETTY CONSISTENT IN HITTING NORTHEAST ND INTO
PORTIONS OF NORTHWEST MN OR AREAS MAINLY NORTH OF HIGHWAY 2 WITH
THE MOST SNOW. THEREFORE WILL STICK WITH THE IDEA OF 3 TO 6 INCHES
ACROSS THIS AREA TAPERING TO LITTLE OR NOTHING ACROSS THE FAR
SOUTH. WIND SPEEDS WILL NOT KICK IN UNTIL LATE TONIGHT. GENERALLY
EXPECTING THIS AFTER MIDNIGHT IN THE FAR NORTH AND AROUND 09Z MON
IN THE KGFK AREA. STRONG WINDS SHOULD NOT HIT THE KFAR AREA DOWN
TO WAHPETON UNTIL 12Z OR LATER. WITH SNOW AND WIND POTENTIAL WILL
ISSUE BLIZZARD WARNINGS FOR NORTHEAST ND INTO THE RED RIVER VALLEY
COUNTIES OF EXTREME NORTHWEST MN STARTING AFTER MIDNIGHT. WITH THE
SNOWFALL UNCERTAINTIES WILL LEAVE THE VALLEY CITY TO FARGO TO ADA
AREA IN THE BLIZZARD WATCH YET. WILL COVER THE FAR SOUTH WITH A
WINTER WEATHER ADVISORY WHICH WILL HAVE TO BE MONITORED IF THE
SNOW MAKES IT FURTHER SOUTH. WENT WITH WINTER STORM WARNING FOR
THE ROSEAU TO KTVF AREA AND LAKE OF THE WOODS AREA FOR 4 TO 6
INCHES OF SNOW WITH GUSTY WINDS. WILL LEAVE THE MAHNOMEN TO KBJI
AREA IN A WINTER STORM WATCH DUE THE UNCERTAINTY WITH SNOWFALL
YET.
MON-WED...WINDS SHOULD BE GOING PRETTY WELL BY SUNRISE AND SHOULD
CONTINUE HOWLING THROUGH THE DAY. LEFT ALL HEADLINES IN EFFECT
THROUGH 00Z TUE EXCEPT THE WINTER WEATHER ADVISORY AREA...WHICH
GOES UNTIL 03Z TUE. OTHER AREAS MAY NEED SOME EXTENDING OR
TWEAKING BUT LATER SHIFTS CAN ALWAYS DO THIS. SFC HIGH BUILDS IN
ON TUE AND SHOULD KEEP THINGS CLEAR THRU MOST OF WED. THIS WILL
SET THE STAGE FOR SOME COLD DAYS AND NIGHTS AND THE POTENTIAL FOR
SOME WIND CHILL ISSUES WHICH WILL NEED TO BE ADDRESSED LATER.
.LONG TERM (THU-SUN)...
MAIN ISSUE REVOLVE AROUND THE NORTHWARD EXTENT OF PRECIPITATION FROM
THE CENTRAL PLAINS STORM. GEM/GFS/EURO ALL BRING SFC LOW INTO
KANSAS THURSDAY THEN MOVE IT NORTHEAST AND WEAKEN WITH WITH TIME
WHILE A LARGE UPPER LOW FORMS IN NEBRASKA AND DRIFTS NORTH INTO THE
EASTERN DAKOTAS FRI. MODEL DIFFERENCES CONCERN THE AMOUNT OF PRECIP
THAT WILL SPREAD NORTH AS STORM WEAKENS...WITH 00Z-12Z ECMWF STILL A
BIT MORE WET THAN GFS AND ESP THE GEM. THAT SAID WILL CONTINUE WITH
GENERAL MODEL BLEND FORECAST OF LIKELY POPS OR HIGH CHANCE IN THE
SOUTH THURSDAY NIGHT INTO FRIDAY...WITH LOWER POPS NORTH. ALL
MODELS KEEP UPPER LOW AROUND SAT-SUN WITH SOME CHANCES FOR VERY
LIGHT SNOW.
&&
.AVIATION...
LOWER CLDS HAVE CLEARED OUT OF ALL THE FCST AREA THIS AFTN LEAVING A
VFR CLOUD DECK IN THE MINNESOTA AND A MORE CIRRUS DECK IN ERN ND.
SOUTH WINDS REMAIN GUSTY TO 25 KTS IN THE RED RIVER VALLEY BUT ARE
TENDING TO SLOWLY DIMINISH AND WILL LOOK FOR THE WIND TO CONTINUE TO
DIMINISH SLOWLY THROUGH EARLY EVENING AS SFC LOW IN SOUTHEAST SASK
MOVES CLOSER. FOCUS TONIGHT INTO MONDAY WILL BE TIMING OF WIND
SHIFT AND THEN VSBY/CIGS WITH SNOW EXPECTED ESP DVL-GFK-TVF
REGIONS. BASED WIND CHANGE AND SNOW TIMING ON RAP MODEL WITH STRONG
WINDS NOT HITTING TIL A FEW HOURS AFTER FRONTAL PASSAGE. VSBYS AND
CIGS MONDAY MAY BE QUITE VARIABLE BUT GENERALLY IFR DVL-GFK-TVF IN
BLSN...FARGO-BJI A MIX OF MVFR AND IFR MAINLY DUE TO VSBYS. WINDS
IN THE RED RIVER VALLEY AND DVL REGION WILL GUST TO 40 KTS OR HIGHER
AT TIMES MONDAY WITH 25 TO 30 KTS PSBL MON AFTN IN BEMIDJI.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WINTER WEATHER ADVISORY FROM 6 AM TO 9 PM CST MONDAY FOR NDZ049-
052-053.
BLIZZARD WARNING FROM 3 AM TO 6 PM CST MONDAY FOR NDZ016-024-
026>030.
BLIZZARD WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST MONDAY FOR
NDZ006>008-014-015-054.
BLIZZARD WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON FOR
NDZ038-039.
MN...WINTER WEATHER ADVISORY FROM 6 AM TO 9 PM CST MONDAY FOR MNZ027-
029>031-040.
WINTER STORM WATCH FROM MIDNIGHT CST TONIGHT THROUGH MONDAY
AFTERNOON FOR MNZ015>017-022.
BLIZZARD WARNING FROM 3 AM TO 6 PM CST MONDAY FOR MNZ001-004-007.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST MONDAY
FOR MNZ005-006-008-009-013-014.
BLIZZARD WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON FOR
MNZ002-003.
&&
$$
GODON/RIDDLE
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
953 PM EST MON FEB 18 2013
.SYNOPSIS...
A STRONG COLD FRONT WILL CROSS THE OHIO VALLEY TONIGHT. HIGH
PRESSURE WILL SETTLE OVER THE MIDWEST WEDNESDAY AND THE RIDGE WILL
WORK INTO THE OHIO VALLEY WEDNESDAY NIGHT. AN ELEVATED WARM FRONT
WILL MOVE NORTH THROUGH THE AREA INTO THE GREAT LAKES REGION ON
THURSDAY NIGHT AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
A COLD FRONT WAS MOVING ACROSS ILLINOIS LATE THIS EVENING. THIS
BOUNDARY WILL TRACK ACROSS THE REGION OVERNIGHT AND BE NEAR THE
EASTERN EDGE OF THE FORECAST AREA BY DAYBREAK. SHOWERS AHEAD OF
THE FRONT WERE MOVING INTO THE WESTERN COUNTIES AND WILL CONTINUE
EAST. HRRR AND RAP GUIDANCE HAVE BEEN SUGGESTING THAT SHOWERS WILL
COME IN A COUPLE OF WAVES. INITIALLY ACTIVITY WILL BE WIDESPREAD
BUT THEN DIMINISH IN COVERAGE LATER TONIGHT. APPEARS THAT A NARROW
LINE COULD THEN COME THROUGH WITH THE ACTUAL BOUNDARY. SOUTH WINDS
WILL REMAIN GUSTY THROUGH THE NIGHT. BUT STRONGER GUSTS HAVE BEEN
OCCURRING IMMEDIATELY AHEAD OF THE PRECIPITATION WHERE LIGHTER MID
LEVEL ECHOES HAVE BEEN FALLING INTO DRIER AIR. TEMPERATURES SHOULD
REMAIN QUITE MILD THROUGH MOST OF THE NIGHT WITH ONLY A SLIGHT
DROP UNTIL THE FRONT MOVES THROUGH AND THEN READINGS WILL START
TO FALL QUICKLY.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
COLD AIR BEHIND THE FRONTAL PASSAGE IN THE MORNING WILL RESULT IN
FALLING TEMPERATURES DURING THE DAY. NOT TOO MUCH MOISTURE WILL BE
AROUND BUT SOME SCATTERED SNOW SHOWERS WILL OCCUR OVER THE
NORTHERN HALF OF THE CWA TUESDAY AFTERNOON IN THE CYCLONIC FLOW
CAPTURING SOME MOISTURE OFF OF LAKE MICHIGAN AND INTERACTING WITH
THE THERMAL DIFFERENCES AND COLD AIR ALOFT.
SKIES SHOULD CLEAR OVERNIGHT AS NORTHWEST WINDS CONTINUE TO PUSH
COLDER AIR INTO THE REGION.
FAIR WEATHER CU WILL POP UP ON WEDNESDAY AND AS THE RIDGE OF HIGH
PRESSURE SETTLES OVER THE OHIO VALLEY IT WILL SET UP A TYPICAL
PATTERN FOR RADIATIONAL COOLING. TEMPERATURES TUESDAY NIGHT AND
WEDNESDAY NIGHT WILL BE IN THE TEENS ON BOTH NIGHTS BUT OCCUR FOR
DIFFERENT REASONS...ADVECTION ON WED MORNING AND RADIATION THURS
MORNING.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
FIRST PART OF THE FORECAST PERIOD WILL BE BUSY AS A STORM SYSTEM
LIFTS OUT OF THE PLAINS. AREA OF HIGH PRESSURE WILL BE CENTERED
ACROSS THE REGION THURSDAY MORNING. 12Z MODEL RUNS ARE SHOWING THE
HIGH WILL BE SLOWER IN RETREATING THURSDAY...WHICH WILL DELAY THE
ONSET OF THE PRECIPITATION THU AFTN. SO HAVE BACKED OFF TO JUST SLGT
CHC POPS SW OF CVG FOR THU. WITH THE HIGH HOLDING STRONGER...THU IS
LOOKING COOLER AND THEREFORE THE OVERALL MODEL PROFILES LOOK COLDER.
THIS IS INDICATING MORE SNOW AND POSSIBLY FREEZING RAIN AND A SLOWER
CHANGE OVER TO LIQUID RAIN LATE THU NGT INTO FRI.
BEST LIFT AND QPF ARE STILL FORECAST TO LIFT N OF THE REGION ON
FRIDAY...AS A WRMFNT GRADUALLY BRINGS IN WARMER AIR ON FRI.
AS MENTIONED YESTERDAY...SECONDARY SYSTEM THAT WAS LIFTING ACROSS
THE SE U.S. OVER THE WEEKEND HAS TRENDED NWD FOR FRI NGT INTO SAT...
SO INTRODUCED CHC POPS FOR THE SE COUNTIES. RIGHT NOW THE PCPN TYPE
LOOKS LIKE RAIN. HIGH PRESSURE LOOKS LIKE IT WILL FINALLY BUILD IN
FOR SUNDAY. ANOTHER CDFNT IS FORECAST TO SWING INTO THE OH VALLEY
MONDAY...BUT THE GFS AND ECMWF ARE SHOWING DIFFERENCES...SO RIGHT
NOW JUST HAVE A MENTION OF CHANCE POPS FOR MONDAY.
THE COOL SE FLOW ON THU WILL KEEP HIGHS IN THE 30S. LOWS THU NGT IN
THE STORM SHOULD RANGE FROM THE MID 20S IN THE N TO LOWER 30S IN NRN
KY. HIGHS FRIDAY SHOULD MAKE THE 40S AS THE REGION GETS WARM
SECTORED. SOME LOCATIONS IN THE NRN KY MIGHT SEE 50S. EXPECT 40S
OVER THE WEEKEND FOR HIGHS WITH LOWS IN THE UPPER 20S TO LOWER 30S
SATURDAY MORNING AND 25 TO 30 SUNDAY MORNING. HIGHS SHOULD BEGIN TO
WARM FOR SUNDAY AND MONDAY REACHING THE MID 40S TO MID 50S BY MONDAY.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
SHOWERS WILL SPREAD ACROSS THE TERMINALS EARLY IN THE PERIOD.
INITIALLY CONDITIONS WILL REMAIN VFR BUT THEN LOWER WITH
OCCASIONAL MODERATE SHOWERS AND MOISTENING OF THE LOWER LEVELS.
COLD FRONT WILL QUICKLY MOVE THROUGH THE TAF SITES BETWEEN 09Z
AND 12Z. CEILINGS WILL LOWER FURTHER WITH GUSTY WEST WINDS. MOST
PRECIPITATION WILL MOVE OFF TO THE EAST WITH THE FRONT. BUT CANNOT
DISCOUNT THE POTENTIAL FOR FLURRIES AND PERHAPS SOME SNOW SHOWERS
AFTER FRONTAL PASSAGE AND WELL INTO THE DAYLIGHT HOURS. LOWER
CONFIDENCE IN THIS PRECLUDES MORE THAN VCSH IN TAFS AT THIS TIME
BUT SOME VISIBILITY RESTRICTIONS MAY HAVE TO BE ADDED IN LATER.
CEILINGS WILL GRADUALLY LIFT LATER IN THE TAF PERIOD BUT MAY NOT
BECOME VFR IN ALL LOCATIONS BY 00Z. GUSTY WEST WINDS WILL PERSIST
WITH ONLY A SLIGHT DECREASE IN STRENGTH BY THE END OF THE PERIOD.
OUTLOOK...MVFR CEILINGS AND GUSTY WEST WINDS MAY PERSIST INTO
TUESDAY EVENING. A WINTRY MIX IS LIKELY TO OCCUR THURSDAY NIGHT
INTO FRIDAY MORNING WITH SOME SNOW AND ICE ACCUMULATION POSSIBLE.
IN ADDITION MVFR CEILINGS AND VISIBILITIES WILL BE LIKELY WITH A
PERIOD OF IFR CONDITIONS POSSIBLE. MVFR CEILINGS MAY CONTINUE
THROUGH FRIDAY NIGHT AND INTO SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...
SHORT TERM...FRANKS
LONG TERM...SITES
AVIATION...
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1246 PM EST SUN FEB 17 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE AREA TODAY. AS IT PUSHES OFF TO
THE EAST THROUGH THE DAY ON MONDAY...INCREASING SOUTHERLY WINDS
WILL PULL WARMER AIR INTO THE REGION. RAIN WILL OVERSPREAD THE
AREA MONDAY NIGHT AHEAD OF AN APPROACHING COLD FRONT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED THE FORECAST TO ACCOUNT FOR PESKY BANDS OF LOW CLOUDS AND
FLURRIES ACROSS WCNTL/CNTL OHIO. 17.12Z KILN SOUNDING WAS QUITE
DRY /PWAT 0.09 INCH/ SUGGESTING MOISTURE IS VERY THIN/SHALLOW BUT
GIVEN VERY COLD THICKNESSES AND NWLY LOW LEVEL FLOW THERE IS STILL
ENOUGH TO WRING OUT A LITTLE -SN ACTIVITY. WITH RAP 900MB FLOW
STILL NNWLY THROUGH MIDDAY EXPECT CLOUDS TO BUILD/DEVELOP SLOWLY
SOUTHEAST THROUGH REMAINDER OF CNTL INTO SCNTL OHIO THROUGH EARLY
AFTERNOON...AND MAY NEED TO UPDATE FORECAST TO BE A LITTLE MORE
BULLISH ON CLOUD COVER IN COMPARISON TO THIS UPDATE. WITH 925MB
TEMPS STILL -14C...AND FLOW NOT EXPECTED TO BACK AROUND TO W/SW
UNTIL MID AFTN...HAVE DROPPED FCST MAX TEMPS A DEGREE OR TWO ALL
AREAS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
HIGH PRESSURE WILL SLIDE EAST OF THE AREA TONIGHT WITH RETURN FLOW
SETTING UP FOR MONDAY AHEAD OF AN APPROACHING COLD FRONT. GOOD WAA
WILL DEVELOP THROUGH THE DAY ON MONDAY AS A 40-50 KNOT 925 JET WORKS
IN FROM THE WEST THROUGH THE AFTERNOON. THIS WILL HELP PUSH
TEMPERATURES WELL ABOVE NORMAL WITH HIGHS RANGING FROM THE UPPER
40S NORTH TO LOWER/MID 50S ACROSS THE SOUTH.
IN A DEVELOPING ISENTROPIC FLOW PATTERN...A FEW SHOWERS COULD
SNEAK INTO OUR WEST LATE IN THE DAY. HOWEVER...BULK OF PCPN SHOULD
HOLD OFF UNTIL MONDAY EVENING WHEN IT OVERSPREADS OUR AREA FROM
THE WEST AND THEN CONTINUES THROUGH THE OVERNIGHT HOURS. THE COLD
FRONT WILL PUSH IN FROM THE WEST LATE MONDAY NIGHT. THIS WILL
ALLOW FOR TEMPERATURES TO DROP OFF QUICKLY ACROSS THE WEST
LATE...WITH RAIN STARTING TO MIX WITH/CHANGE TO SNOW. GOOD CAA
WILL OVERSPREAD THE AREA THROUGH TUESDAY MORNING WITH ANY
LINGERING RAIN CHANGING OVER TO ALL SNOW. AS DRIER AIR MOVES IN
FROM THE WEST...PCPN SHOULD TAPER OFF TO A FEW SHOWERS HEADING
THROUGH THE REST OF THE DAY. EXPECT ANY SNOW ACCUMULATIONS TO BE ON
THE LIGHT SIDE AS MORE SIGNIFICANT PCPN SHOULD BE ENDING AS
THE COLDER AIR WORKS IN. GIVEN THE GOOD CAA ON TUESDAY...DO NOT
EXPECT MUCH TEMPERATURE RECOVERY...WITH EARLY HIGHS LIKELY ACROSS
THE EAST WITH TEMPERATURES THEN FALLING OFF THROUGH THE REST OF
THE DAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
HIGH PRESSURE BUILDS DOWN INTO THE LOWER OHIO VALLEY TUE NIGHT
INTO WED BEFORE LIFTING NE ACROSS THE FA WED NGT. THIS SHOULD
PROVIDE DRY CONDITIONS FOR THE PERIOD...WITH NRN SECTIONS SEEING
MORE CLOUDS THAN THE S TUE NGT AND WED...BEFORE MOSTLY CLEAR SKIES
PREVAIL WED NGT.
SYSTEM DIGS INTO THE SRN ROCKIES WED NGT...THEN EJECTS OUT THU
INTO THU NGT. MODELS ARE SHOWING THEIR TYPICAL SPREAD. THE CMC IS
THE QUICKEST THIS RUN IN BRINGING RETURN PCPN TO THE FA THU AFTN.
THE 12Z RUNS OF THE GFS AND ECMWF ARE SLOWER...LIMITING POPS TO
THE SW. THICKNESSES WILL BE COLD ENUF FOR SOME RAIN/SNOW AT THE
ONSET. AS THE CENTER OF THE SYSTEM LIFTS OUT THRU THE PLAINS...AN
AREA OF PCPN WILL BE PUSHED ACROSS THE FA THU NGT INTO FRI. PCPN
WILL EITHER BE SN OR RA/SN MIX UNTIL A WRMFNT GRADUALLY BRINGS IN
WARMER AIR CHANGING THE PCPN TO RA BEFORE IT ENDS ON FRIDAY. HIGH
PRESSURE THEN BUILDS IN FOR FRIDAY.
COLD AIR WILL WORK IN TUESDAY NIGHT DROPPING TEMPERATURES IN THE
TEENS AND LOWER 20S. THE COOL NLY FLOW ON WED WILL KEEP TEMPS DOWN
IN THE UPPER 20S N TO THE MID 30S NRN KY. THE CLEAR SKIES WILL
ALLOW TEMPERATURES TO DROP BACK INTO THE TEENS AND LOWER 20S
AGAIN. ONLY EXPECT HIGHS ON THU TO MAKE THE 30S AHEAD OF THE STORM
SYSTEM...BUT WITH RISING TEMPS THU NGT. HIGHS FRIDAY SHOULD MAKE
THE 40S AS THE REGION GETS WARM SECTORED.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
PRIMARY BAND OF MVFR CIGS WITH -SN HAS BEEN THROUGH DAY/CMH THIS
MORNING AND NOW INDICATIONS THAT THIS IS BEGINNING TO BREAK UP AS
LOW LEVEL FLOW IS STARTING TO BACK MORE SUBSTANTIALLY NOW.
NUMEROUS OTHER CELLULAR CUMULUS NOW POPPING AROUND THAT MAIN BAND
AND MAY AFFECT ALL TERMINALS WITH A BRIEF MVFR/VFR CIG THIS
AFTN...BUT FOR THE MOST PART EXPECT SCT CUMULUS TO REMAIN NORTH OF
CVG/LUK...AFFECTING DAY/ILN AND OF COURSE LCK/CMH WHERE CLOUDS
REMAIN THE THICKEST. AS RIDGE AXIS COMES ACROSS THE SITES LATE
THIS AFTN/EVE...WINDS SHOULD BECOME VARIABLE/LIGHT ALL SITES AND
THEN IMMEDIATELY INCREASE FROM SOUTHEAST AFT 03Z OR SO. MORE
SUBSTANTIAL DECREASE IN CUMULUS SHOULD ALSO OCCUR DURING THIS TIME. LIGHT
SELY FLOW EXPECTED OVERNIGHT WITH MORE SUBSTANTIAL STRENGTHENING
/WITH GUSTS/ EXPECTED ON MONDAY AS FLOW BECOMES MORE SLY. DO
EXPECT A BAND OF WARM ADVECTION VFR CIGS TO SPREAD ACROSS THE
SITES AFTER 07Z AND THEN EXIT MOST AREAS BY 15Z AS MUCH WARMER AIR
STREAMS IN ALOFT. NEXT CYCLE OF CVG TAFS WILL NEED TO ADDRESS RAIN
MOVING INTO THAT AREA IN THE 24-30 HOUR FORECAST.
OUTLOOK...MVFR CIGS AND VSBYS POSSIBLE MONDAY NIGHT AND EARLY
TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...JGL
NEAR TERM...BINAU
SHORT TERM...JGL
LONG TERM...SITES
AVIATION...BINAU
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
949 AM EST SUN FEB 17 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE AREA TODAY. AS IT PUSHES OFF TO
THE EAST THROUGH THE DAY ON MONDAY...INCREASING SOUTHERLY WINDS
WILL PULL WARMER AIR INTO THE REGION. RAIN WILL OVERSPREAD THE
AREA MONDAY NIGHT AHEAD OF AN APPROACHING COLD FRONT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED THE FORECAST TO ACCOUNT FOR PESKY BANDS OF LOW CLOUDS AND
FLURRIES ACROSS WCNTL/CNTL OHIO. 17.12Z KILN SOUNDING WAS QUITE
DRY /PWAT 0.09 INCH/ SUGGESTING MOISTURE IS VERY THIN/SHALLOW BUT
GIVEN VERY COLD THICKNESSES AND NWLY LOW LEVEL FLOW THERE IS STILL
ENOUGH TO WRING OUT A LITTLE -SN ACTIVITY. WITH RAP 900MB FLOW
STILL NNWLY THROUGH MIDDAY EXPECT CLOUDS TO BUILD/DEVELOP SLOWLY
SOUTHEAST THROUGH REMAINDER OF CNTL INTO SCNTL OHIO THROUGH EARLY
AFTERNOON...AND MAY NEED TO UPDATE FORECAST TO BE A LITTLE MORE
BULLISH ON CLOUD COVER IN COMPARISON TO THIS UPDATE. WITH 925MB
TEMPS STILL -14C...AND FLOW NOT EXPECTED TO BACK AROUND TO W/SW
UNTIL MID AFTN...HAVE DROPPED FCST MAX TEMPS A DEGREE OR TWO ALL
AREAS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
HIGH PRESSURE WILL SLIDE EAST OF THE AREA TONIGHT WITH RETURN FLOW
SETTING UP FOR MONDAY AHEAD OF AN APPROACHING COLD FRONT. GOOD WAA
WILL DEVELOP THROUGH THE DAY ON MONDAY AS A 40-50 KNOT 925 JET WORKS
IN FROM THE WEST THROUGH THE AFTERNOON. THIS WILL HELP PUSH
TEMPERATURES WELL ABOVE NORMAL WITH HIGHS RANGING FROM THE UPPER
40S NORTH TO LOWER/MID 50S ACROSS THE SOUTH.
IN A DEVELOPING ISENTROPIC FLOW PATTERN...A FEW SHOWERS COULD
SNEAK INTO OUR WEST LATE IN THE DAY. HOWEVER...BULK OF PCPN SHOULD
HOLD OFF UNTIL MONDAY EVENING WHEN IT OVERSPREADS OUR AREA FROM
THE WEST AND THEN CONTINUES THROUGH THE OVERNIGHT HOURS. THE COLD
FRONT WILL PUSH IN FROM THE WEST LATE MONDAY NIGHT. THIS WILL
ALLOW FOR TEMPERATURES TO DROP OFF QUICKLY ACROSS THE WEST
LATE...WITH RAIN STARTING TO MIX WITH/CHANGE TO SNOW. GOOD CAA
WILL OVERSPREAD THE AREA THROUGH TUESDAY MORNING WITH ANY
LINGERING RAIN CHANGING OVER TO ALL SNOW. AS DRIER AIR MOVES IN
FROM THE WEST...PCPN SHOULD TAPER OFF TO A FEW SHOWERS HEADING
THROUGH THE REST OF THE DAY. EXPECT ANY SNOW ACCUMULATIONS TO BE ON
THE LIGHT SIDE AS MORE SIGNIFICANT PCPN SHOULD BE ENDING AS
THE COLDER AIR WORKS IN. GIVEN THE GOOD CAA ON TUESDAY...DO NOT
EXPECT MUCH TEMPERATURE RECOVERY...WITH EARLY HIGHS LIKELY ACROSS
THE EAST WITH TEMPERATURES THEN FALLING OFF THROUGH THE REST OF
THE DAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
HIGH PRESSURE BUILDS DOWN INTO THE LOWER OHIO VALLEY TUE NIGHT
INTO WED BEFORE LIFTING NE ACROSS THE FA WED NGT. THIS SHOULD
PROVIDE DRY CONDITIONS FOR THE PERIOD...WITH NRN SECTIONS SEEING
MORE CLOUDS THAN THE S TUE NGT AND WED...BEFORE MOSTLY CLEAR SKIES
PREVAIL WED NGT.
SYSTEM DIGS INTO THE SRN ROCKIES WED NGT...THEN EJECTS OUT THU
INTO THU NGT. MODELS ARE SHOWING THEIR TYPICAL SPREAD. THE CMC IS
THE QUICKEST THIS RUN IN BRINGING RETURN PCPN TO THE FA THU AFTN.
THE 12Z RUNS OF THE GFS AND ECMWF ARE SLOWER...LIMITING POPS TO
THE SW. THICKNESSES WILL BE COLD ENUF FOR SOME RAIN/SNOW AT THE
ONSET. AS THE CENTER OF THE SYSTEM LIFTS OUT THRU THE PLAINS...AN
AREA OF PCPN WILL BE PUSHED ACROSS THE FA THU NGT INTO FRI. PCPN
WILL EITHER BE SN OR RA/SN MIX UNTIL A WRMFNT GRADUALLY BRINGS IN
WARMER AIR CHANGING THE PCPN TO RA BEFORE IT ENDS ON FRIDAY. HIGH
PRESSURE THEN BUILDS IN FOR FRIDAY.
COLD AIR WILL WORK IN TUESDAY NIGHT DROPPING TEMPERATURES IN THE
TEENS AND LOWER 20S. THE COOL NLY FLOW ON WED WILL KEEP TEMPS DOWN
IN THE UPPER 20S N TO THE MID 30S NRN KY. THE CLEAR SKIES WILL
ALLOW TEMPERATURES TO DROP BACK INTO THE TEENS AND LOWER 20S
AGAIN. ONLY EXPECT HIGHS ON THU TO MAKE THE 30S AHEAD OF THE STORM
SYSTEM...BUT WITH RISING TEMPS THU NGT. HIGHS FRIDAY SHOULD MAKE
THE 40S AS THE REGION GETS WARM SECTORED.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
LINGERING LOW LEVEL MOISTURE DUE TO NORTHWESTERLY FLOW OFF THE
GREAT LAKES WILL BRING A MIX OF VFR AND MVFR CLOUDS ACROSS THE
AREA THROUGHOUT THE DAY. THE BEST CHANCE FOR MVFR CIGS WILL BE
ACROSS THE NORTH...CLOSER TO THE LAKES. AS HIGH PRESSURE SHIFTS
EAST OF OUR AREA THIS EVENING...NORTHWESTERLY FLOW WILL
CEASE...AND SOUTHERLY FLOW WILL BEGIN TO DEVELOP. AS THIS
OCCURS...LOW LEVEL CLOUDS WILL DECREASE. THIS SHOULD RESULT IN VFR
CONDITIONS FOR ALL TERMINALS FROM THIS EVENING THROUGH SUNDAY
MORNING.
OUTLOOK...MVFR CIGS AND VSBYS POSSIBLE MONDAY NIGHT AND EARLY
TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...JGL
NEAR TERM...BINAU
SHORT TERM...JGL
LONG TERM...SITES
AVIATION...LATTO
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1150 AM CST SUN FEB 17 2013
.DISCUSSION.../ISSUED AT 1015 AM CST/
SURFACE LOW PRESSURE MOVING ACROSS THE CANADIAN BORDER WILL PUSH A
COLD FRONT THROUGH THE AREA TONIGHT. TODAY WILL BE A MILD AND BREEZY
DAY OUT AHEAD OF THIS FRONT. STILL EXPECTING SOUTHERLY WINDS TO
CONTINUE TO INCREASE THIS AFTERNOON...WITH GUSTS AROUND 30
MPH...ESPECIALLY ALONG AND EAST OF INTERSTATE 29. SEEING A BIT MORE
CIRRUS THAN FORECAST..SO WENT AHEAD AND UPPED CLOUD COVER...HOWEVER
SHOULD STILL SEE PARTLY SUNNY SKIES. CIRRUS PROBABLY WONT HAVE TOO
MUCH OF AN IMPACT ON HIGHS...ESPECIALLY SINCE A THINNER AREA SHOULD
BE OVER THE CWA FOR THE NEXT SEVERAL HOURS. GOING HIGHS LOOK IN
PRETTY GOOD SHAPE...ALTHOUGH DID GO AHEAD AND RAISE HIGHS A COUPLE
DEGREES IN OUR SOUTH BASED ON LATEST RAP AND HRRR TRENDS. /CHENARD
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
VFR CONDITIONS WILL CONTINUE THROUGH THE DAY. WINDS WILL BE BREEZY
THROUGH THIS AFTERNOON OUT OF THE SOUTH...WITH GUSTS AROUND 25
KTS...ESPECIALLY ALONG AND EAST OF INTERSTATE 29. COLD FRONT WILL
MOVE THROUGH TONIGHT...WITH WINDS TURNING WESTERLY AND EVENTUALLY
NORTHWESTERLY. WINDS WILL BEGIN TO PICK UP BY MORNING...WITH GUSTS
UP TO 35 KTS BY MID MORNING. STRATUS WILL LIKELY MAKE A RETURN IN
THE MORNING AS WELL...WITH MVFR CIGS EXPECTED ACROSS MOST OF THE
CWA. /CHENARD
&&
.PREVIOUS DISCUSSION.../ISSUED AT 243 AM CST/
ONE FINAL MILD DAY TODAY BEFORE A WEEK OF BELOW NORMAL TEMPERATURES
COMING UP. YESTERDAY GOT A LITTLE WARMER THAN ANTICIPATED AND SEE NO
REASON WHY TEMPERATURES WILL NOT WARM NICELY TODAY. COMPARING
YESTERDAYS 925MB TEMPERATURES WITH WHAT IS EXPECTED TODAY PLAN ON
MOST LOCATIONS ADDING ABOUT 5 TO 10 DEGREES TO HIGHS TODAY WITH LESS
CLOUD COVER AND A WARMER LOW LEVEL THERMAL FIELD. SO...HIGHS SHOULD
RANGE FROM THE MID 30S ALONG HIGHWAY 14 TO AROUND 50 DOWN THE
MISSOURI RIVER CORRIDOR. A BREEZY SOUTH WIND WILL ACCOMPANY THE WARM
UP SO THE WARMER READINGS WILL COME WITH A BIT OF A CHILL.
WINDS WILL GRADUALLY TURN TO THE NORTHWEST OVERNIGHT WITH MID AND
HIGH CLOUDS EXPECTED TO INCREASE AS WELL. THIS WILL KEEP
TEMPERATURES FROM FALLING SO ANTICIPATE A MILD MONDAY
MORNING...ALBEIT BRIEFLY AS THE FRONT SURGES SOUTH FAIRLY QUICKLY
MONDAY MORNING. LOW TEMPERATURES WILL MAINLY BE IN THE 20S WITH HIGH
TEMPERATURES ON MONDAY REACHED FAIRLY EARLY IN THE MORNING THEN
FALLING THROUGH THE DAY. STILL LOOKS LIKE NEAR WIND ADVISORY
CRITERIA BUT WILL HOLD OFF ON ANY ADVISORIES AT THIS TIME. WITH
925MB WINDS AROUND 30 TO 35 KNOTS THE SURFACE WIND USUALLY DOES NOT
QUITE REACH WIND ADVISORY CRITERIA BUT IF MODELS TREND CLOSER TO 40
KNOTS AN ADVISORY MAY BE NEEDED AS MIXING WILL BE SIGNIFICANT WITH
STRONG COLD AIR ADVECTION THROUGH THE DAY.
MUCH COLDER AIR WILL WORK INTO THE AREA MONDAY NIGHT INTO TUESDAY
LEADING TOWARDS ONE OF THE COLDER PERIODS THIS WINTER. TUESDAY
MORNING LOWS WILL DROP TO AROUND ZERO TO BELOW ZERO FROM INTERSTATE
90 NORTH AND WHEN COUPLED WITH A FAIRLY STOUT NORTH WIND...WIND
CHILL VALUES WILL DROP TO 20 TO 30 BELOW ZERO FOR A TIME FROM ABOUT
MIDNIGHT TO NOON TUESDAY. A WIND CHILL ADVISORY MAY BE NEEDED FOR
THIS TIME FRAME. ALSO OF CONCERN LATE MONDAY AFTERNOON AND MONDAY
NIGHT WILL BE A WEAK WAVE MOVING EAST THROUGH THE REGION WHICH COULD
BRING SOME LIGHT SNOW AND BLOWING SNOW DOWN THE HIGHWAY 14 CORRIDOR.
WILL MAINTAIN SOME LOWER END POPS TO ACCOMMODATE THIS THREAT.
IN THE LATTER PERIODS(WED/SAT)...THIS PERIOD CONTINUES TO BE
DOMINATED BY THE POTENTIAL FOR A WINTER STORM ON THURSDAY AND
THURSDAY NIGHT. ALL INDICATIONS ARE THAT THIS WILL LEAN MORE TOWARDS
AN ISENTROPIC WIDESPREAD MODERATE TO HEAVY SNOW EVENT VS. A FRONTAL
BAND OR A RAPIDLY DEEPENING HIGH WIND/BLIZZARD LIKE EVENT. SO MAYBE
LOOKING AT 5 TO 10 INCHES OF SNOWFALL WITH WINDS IN THE 15 TO 30 MPH
RANGE AND NOT BECOMING EXCESSIVELY COLD BEHIND THE SYSTEM. WITH THIS
IN MIND ANTICIPATE THAT ANY STORM TRACK THAT KEEPS THE UPPER LEVEL
LOW ALONG AND SOUTH OF THE CWA WILL BRING A DECENT AMOUNT OF SNOW TO
MOST OF THE AREA. THE LATEST ECMWF IS TAKING A BIT OF A TURN TO THE
NORTHWEST WHICH IF THIS TREND CONTINUED COULD TAKE A LOT OF THE
HEAVIEST ACTIVITY TO THE NORTH AND WEST OF THE AREA. HOWEVER...FEEL
THAT THERE WILL BE PLENTY OF MOISTURE WITH THIS SYSTEM THAT IT WILL
TAKE SOME PRETTY BIG CHANGES TO THE NORTH AND WEST TO NOT GET SOME
MEASURABLE SNOWFALL. THUS WILL CONTINUE WITH 80+ POPS FOR THURSDAY
AND THURSDAY NIGHT MANY AREAS AND CONTINUE TO HINT AT THE POTENTIAL
FOR A WINTER STORM/HEAVY SNOW IN THE HWO. GENERALLY THINKING HIGHS
IN THE UPPER TEENS TO 20S AS THE STORM EXITS ON FRIDAY AND SATURDAY.
/08
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1016 AM CST SUN FEB 17 2013
.DISCUSSION.../ISSUED AT 1015 AM CST/
SURFACE LOW PRESSURE MOVING ACROSS THE CANADIAN BORDER WILL PUSH A
COLD FRONT THROUGH THE AREA TONIGHT. TODAY WILL BE A MILD AND BREEZY
DAY OUT AHEAD OF THIS FRONT. STILL EXPECTING SOUTHERLY WINDS TO
CONTINUE TO INCREASE THIS AFTERNOON...WITH GUSTS AROUND 30
MPH...ESPECIALLY ALONG AND EAST OF INTERSTATE 29. SEEING A BIT MORE
CIRRUS THAN FORECAST..SO WENT AHEAD AND UPPED CLOUD COVER...HOWEVER
SHOULD STILL SEE PARTLY SUNNY SKIES. CIRRUS PROBABLY WONT HAVE TOO
MUCH OF AN IMPACT ON HIGHS...ESPECIALLY SINCE A THINNER AREA SHOULD
BE OVER THE CWA FOR THE NEXT SEVERAL HOURS. GOING HIGHS LOOK IN
PRETTY GOOD SHAPE...ALTHOUGH DID GO AHEAD AND RAISE HIGHS A COUPLE
DEGREES IN OUR SOUTH BASED ON LATEST RAP AND HRRR TRENDS. /CHENARD
.PREVIOUS DISCUSSION.../ISSUED AT 243 AM CST/
ONE FINAL MILD DAY TODAY BEFORE A WEEK OF BELOW NORMAL TEMPERATURES
COMING UP. YESTERDAY GOT A LITTLE WARMER THAN ANTICIPATED AND SEE NO
REASON WHY TEMPERATURES WILL NOT WARM NICELY TODAY. COMPARING
YESTERDAYS 925MB TEMPERATURES WITH WHAT IS EXPECTED TODAY PLAN ON
MOST LOCATIONS ADDING ABOUT 5 TO 10 DEGREES TO HIGHS TODAY WITH LESS
CLOUD COVER AND A WARMER LOW LEVEL THERMAL FIELD. SO...HIGHS SHOULD
RANGE FROM THE MID 30S ALONG HIGHWAY 14 TO AROUND 50 DOWN THE
MISSOURI RIVER CORRIDOR. A BREEZY SOUTH WIND WILL ACCOMPANY THE WARM
UP SO THE WARMER READINGS WILL COME WITH A BIT OF A CHILL.
WINDS WILL GRADUALLY TURN TO THE NORTHWEST OVERNIGHT WITH MID AND
HIGH CLOUDS EXPECTED TO INCREASE AS WELL. THIS WILL KEEP
TEMPERATURES FROM FALLING SO ANTICIPATE A MILD MONDAY
MORNING...ALBEIT BRIEFLY AS THE FRONT SURGES SOUTH FAIRLY QUICKLY
MONDAY MORNING. LOW TEMPERATURES WILL MAINLY BE IN THE 20S WITH HIGH
TEMPERATURES ON MONDAY REACHED FAIRLY EARLY IN THE MORNING THEN
FALLING THROUGH THE DAY. STILL LOOKS LIKE NEAR WIND ADVISORY
CRITERIA BUT WILL HOLD OFF ON ANY ADVISORIES AT THIS TIME. WITH
925MB WINDS AROUND 30 TO 35 KNOTS THE SURFACE WIND USUALLY DOES NOT
QUITE REACH WIND ADVISORY CRITERIA BUT IF MODELS TREND CLOSER TO 40
KNOTS AN ADVISORY MAY BE NEEDED AS MIXING WILL BE SIGNIFICANT WITH
STRONG COLD AIR ADVECTION THROUGH THE DAY.
MUCH COLDER AIR WILL WORK INTO THE AREA MONDAY NIGHT INTO TUESDAY
LEADING TOWARDS ONE OF THE COLDER PERIODS THIS WINTER. TUESDAY
MORNING LOWS WILL DROP TO AROUND ZERO TO BELOW ZERO FROM INTERSTATE
90 NORTH AND WHEN COUPLED WITH A FAIRLY STOUT NORTH WIND...WIND
CHILL VALUES WILL DROP TO 20 TO 30 BELOW ZERO FOR A TIME FROM ABOUT
MIDNIGHT TO NOON TUESDAY. A WIND CHILL ADVISORY MAY BE NEEDED FOR
THIS TIME FRAME. ALSO OF CONCERN LATE MONDAY AFTERNOON AND MONDAY
NIGHT WILL BE A WEAK WAVE MOVING EAST THROUGH THE REGION WHICH COULD
BRING SOME LIGHT SNOW AND BLOWING SNOW DOWN THE HIGHWAY 14 CORRIDOR.
WILL MAINTAIN SOME LOWER END POPS TO ACCOMMODATE THIS THREAT.
IN THE LATTER PERIODS(WED/SAT)...THIS PERIOD CONTINUES TO BE
DOMINATED BY THE POTENTIAL FOR A WINTER STORM ON THURSDAY AND
THURSDAY NIGHT. ALL INDICATIONS ARE THAT THIS WILL LEAN MORE TOWARDS
AN ISENTROPIC WIDESPREAD MODERATE TO HEAVY SNOW EVENT VS. A FRONTAL
BAND OR A RAPIDLY DEEPENING HIGH WIND/BLIZZARD LIKE EVENT. SO MAYBE
LOOKING AT 5 TO 10 INCHES OF SNOWFALL WITH WINDS IN THE 15 TO 30 MPH
RANGE AND NOT BECOMING EXCESSIVELY COLD BEHIND THE SYSTEM. WITH THIS
IN MIND ANTICIPATE THAT ANY STORM TRACK THAT KEEPS THE UPPER LEVEL
LOW ALONG AND SOUTH OF THE CWA WILL BRING A DECENT AMOUNT OF SNOW TO
MOST OF THE AREA. THE LATEST ECMWF IS TAKING A BIT OF A TURN TO THE
NORTHWEST WHICH IF THIS TREND CONTINUED COULD TAKE A LOT OF THE
HEAVIEST ACTIVITY TO THE NORTH AND WEST OF THE AREA. HOWEVER...FEEL
THAT THERE WILL BE PLENTY OF MOISTURE WITH THIS SYSTEM THAT IT WILL
TAKE SOME PRETTY BIG CHANGES TO THE NORTH AND WEST TO NOT GET SOME
MEASURABLE SNOWFALL. THUS WILL CONTINUE WITH 80+ POPS FOR THURSDAY
AND THURSDAY NIGHT MANY AREAS AND CONTINUE TO HINT AT THE POTENTIAL
FOR A WINTER STORM/HEAVY SNOW IN THE HWO. GENERALLY THINKING HIGHS
IN THE UPPER TEENS TO 20S AS THE STORM EXITS ON FRIDAY AND SATURDAY.
/08
&&
.AVIATION.../FOR THE 12Z TAF ISSUANCE/
VERY LOCAL CEILINGS BELOW 1K FEET THROUGH 16Z WITH PATCHES AT 12Z
JUST WEST OF HON AND NORTHEAST OF FSD. OTHERWISE VFR CONDITIONS
EXPECTED THROUGH 18/12Z. CEILINGS WILL BE UNLIMITED MOST OF THIS
TIME BUT MAY LOWER TO 3-5K FEET NORTH AFTER 18/06Z. FURTHER LOWERING
TO MVFR CEILINGS POSSIBLE OVER AREA AFTER 18/12Z. SOUTH WINDS
THROUGH 18/03Z SHOULD GRADUALLY BECOME WEST AND NORTHWEST AFTER
18/03Z BUT GUSTS ARE EXPECTED TO STAY BELOWE 25 KNOTS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
916 PM EST MON FEB 18 2013
.SYNOPSIS...
A COLD FRONT IS GOING TO MOVE FROM THE MISSISSIPPI VALLEY TONIGHT
INTO THE CENTRAL APPALACHIANS BY LATE TUESDAY MORNING...AND
THROUGH OUR AREA BY TUESDAY EVENING.
HIGH PRESSURE WILL WORK IN FROM THE UPPER MIDWEST WEDNESDAY
SLIDING EAST OVER THE AREA BY THURSDAY MORNING.
&&
.NEAR TERM /THROUGH TUESDAY/...
AS OF 810 PM EST MONDAY...
CONVECTIVE BAND NOW ALONG THE MISS RIVER REMAINS THE MAIN CONCERN
LATER TONIGHT AS IT ZIPS EAST AND ENCOUNTERS RESIDUAL COLD/DRY AIR
STILL LOCKED IN ACROSS THE REGION. TIMING/QPF THE MAIN ASPECTS
ACROSS THE WESTERN THIRD BY MORNING...AND EAST OF THE BLUE RIDGE
EARLY TUESDAY. LATEST NAM AND RAP REMAIN A BIT SLOW WITH INIT ON
CURRENT AXIS OF PRECIP TO THE WEST...SO PLANNING TO STAY FASTER
WITH ARRIVAL ESPCLY GIVEN SUCH A STRONG 3H JETLET PASSING THRU THE
BOTTOM OF THE UPPER TROF JUST WEST OF THE MOUNTAINS BY DAYBREAK.
LATEST FORECAST SOUNDINGS SUGGEST QUICK WET BULBING DOWN TO AN
ISOTHERMAL LAYER AROUND FREEZING WESTERN HALF LATE WITH VERY
LITTLE WARM NOSE SUPPORTIVE OF MORE SLEET/SNOW EXCEPT PERHAPS THE
FAR SW WHERE THE BOUNDARY LAYER MAY BE A BIT WARM FOR LITTLE MORE
THAN RAIN/SLEET. LATEST LOCAL RNK WRK ALSO SHOWING HEAVIER BANDS
OF PRECIP FAR WEST AT THE ONSET SO MAIN CHANGE WAS TO UP QPF
ALONG/WEST OF THE I-77 CORRIDOR BY 12Z...AND BOOST POPS/SNOWFALL
FOR THE NW NC RIDGES INTO GRAYSON WHERE 1-2+ INCHES LOOK POSSIBLE
BEFORE PRECIP TAPERS OR GOES TO -DZ TUESDAY. ELSW STILL THINKING
A MIXED BAG...BUT LIKELY MORE SNOW IN THE TYPICAL DEEPER WEDGE
AREAS...WITH SOME FREEZING RAIN POSSIBLE VALLEYS EARLY TUESDAY
AFTER SURFACE TEMPS HAVE BEEN BRIEFLY COOLED BELOW FREEZING.
TIMING EAST OF THE ADVISORY CRITICAL IN WHETHER OR NOT ANYTHING
FROZEN OCCURS OR IS MOSTLY A RAIN EVENT WITH SOME SLEET AT THE
ONSET ESPCLY IF ARRIVAL IS AN HOUR OR TWO AFTER DAYBREAK. COULD
POSSIBLY SEE LOCATIONS ON THE VIRGINIA SIDE...OUT EAST OF THE
HIGHER RIDGES TO HIGHWAY 29...GET A QUICK SLEET/SNOW COATING BUT
ONLY IF PRECIP IS FASTER. OTRW MOSTLY LIGHT QPF AND LIQUID AT
THIS POINT.
SOUTH WINDS JUST AHEAD OF THE FRONT STILL LOOK CLOSE TO WARNING
CRITERIA TAZEWELL/BLF REGION PER LATEST MODEL CROSS SECTIONS.
HOWEVER LIKELY ONLY A QUICK BURST RIGHT AHEAD OF THE PRECIP
LATE...AND THEN PERHAPS STRONGER LATER TUESDAY BEHIND THE FRONT
WHEN MOMENTUM TRANSFER IS BETTER OUTSIDE OF THE RAIN/SNOW. THUS
WILL KEEP GUSTS TO HIGH END ADVISORY WITHIN THE WINTER WEATHER
PRODUCT FOR OVERNIGHT AT THIS POINT.
TEMPS SLOW TO FALL THIS EVENING OUTSIDE THE VALLEYS WITH A DECENT
SOUTH WIND KICKING IN WELL AHEAD OF THE FRONT. THEREFORE ADJUSTING
THE TEMP CURVE A BIT TO REFLECT COLDER VALUES MORE WITH PRECIP
LATER THAN EARLY RAD COOLING. HOWEVER DEWPOINTS REMAIN DRY ENOUGH
TO WET BULB DOWN TO THE LOW/MID 30S UNLESS THE WARM ADVECTION IS
JUST TOO STRONG...AND THE INIT PRECIP LIGHT...ALLOWING A QUICK
RISE IN DEPRESSIONS LATE.
PREVIOUS DISCUSSION...
EXPECTING A NUISANCE TYPE WINTER WEATHER EVENT LATE TONIGHT INTO
LATE TUESDAY MORNING...WHICH ALTHOUGH AMOUNTS OF WINTRY WEATHER
WILL NOT BE REACHING OUR ADVISORY LEVELS PER SE...THE MORNING
COMMUTE WILL BE WHEN MOST OF THIS WILL BE OCCURRING...HENCE THE
ADVISORY. NOT TOO IMPRESSED WITH FREEZING RAIN CHANCES...DESPITE
THE STRONG LOW LVL JET ARRIVING LATE TONIGHT. ATTM...MODEL
SOUNDINGS FORECAST ENOUGH DRY AIR AND SUB-FREEZING WET BULBS THAT
WHEN PRECIPITATION ARRIVES ACROSS MOST OF THE AREA IT SHOULD START
AS SNOW. EXCEPTION WILL BE ACROSS THE FAR WRN ZONES WHERE MORE OF
SW WIND WILL HELP KEEP THE LOW LVLS WARMER WITH RAIN MIXING IN.
MADE NO CHANGES TO THE ADVISORY...EXCEPT ADDING THE MENTION OF
HIGHER WIND GUSTS OVER THE TYPICAL AREAS FROM BLF-MOUNT ROGERS.
THE 8H JET OF 60 KNOTS AND SFC WINDS OUT OF THE SSE ARE USUALLY
ENOUGH TO GIVE THE CLINCH RIVER VALLEY/BURKES GARDEN AND OTHER
AREAS AROUND THE MOUNTAIN EMPIRE STRONG WIND GUSTS. ATTM...DO NOT
SEE A HIGH WIND WARNING ALTHOUGH WOULD NOT BE SURPRISED IF PLACES
LIKE MOUNT ROGERS OR BURKES GARDEN EXPERIENCE GUSTS OVER 58 MPH.
SOME SMALL TREES AND LIMBS WILL BE FALLING...WITH ISOLATED POWER
OUTAGES POSSIBLE.
GOING TOWARD THE MODEL MEAN OF THE NAM/GFS SHOWS THE FRONT PUSHING
ACROSS THE BLUE RIDGE BY EARLY AFTERNOON. HAVE PRECIP CHANGING TO
MORE RAIN BEFORE THEN WITH SNOW LINGERING OVER THE HIGHER
ELEVATIONS...BECOMING MORE SHOWERY AFTER FRONTAL PASSAGE. THINGS
DRY OUT BY THE AFTERNOON IN THE SOUTHWEST WITH A QUICK DRYING
ARRIVING ELSEWHERE BY THE END OF THE DAY. WINDS ARE GOING TO SHIFT
WEST AND GUST OVER 40 MPH AT TIMES...BUT NOT GOING WITH WIND
ADVISORY AS 8H WINDS ARE NOT AS STRONG...PER NAM/GFS.
TEMPS WILL BE FALLING QUICK THIS EVENING BEFORE CLOUDS
ARRIVE...THEN STEADY OR RISE AFTER MIDNIGHT BEFORE FALLING AGAIN
WHEN PRECIP ARRIVES IN THE WEST BY DAWN. THIS WILL BE PROBLEMATIC
WITH SFC TEMPS AND THE WINTRY PRECIP.
DESPITE THIS WINTRY EVENT...TEMPS TUESDAY WILL BE SEASOANAL WITH
40S WEST AND LOWER 50S EAST.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
AS OF 300 PM MONDAY...
STRONG COLD FRONT WILL BE WELL EAST OF THE CWA TUE NIGHT WITH STRONG
COLD AIR ADVECTION IN ITS WAKE. A FEW LINGERING MOUNTAIN SNOW
SHOWERS POSSIBLE IN MOST FAVORED UPSLOPE AREAS BUT OTHERWISE WINDY
AND COLD WITH CLEARING SKIES OVERNIGHT. H85 TEMPS FALL BACK TO -10C
TO -15C RANGE BY 12Z WED...WITH LOW TEMPS LIKELY TO BE UPPER TEENS
NW TO MID-20S EAST. 12Z NAM ALSO SHOWS NW WINDS AT H85 IN THE 50-60
KT RANGE EARLY WED MORNING WHICH MAY WARRANT A WIND
ADVISORY...ESPECIALLY ALONG EXPOSED RIDGETOPS. EITHER WAY WILL BE A
VERY CHILLY START TO THE DAY. WITH GRADIENT BETWEEN DEPARTING
SURFACE LOW OVER THE MARITIMES AND 1040 MB RIDGE OF HIGH PRESSURE
BUILDING SOUTHEAST FROM THE UPPER PLAINS WED LOOKS TO REMAINS
BREEZY...ALBEIT WINDS SLOWLY DIMINISHING. TEMPS RANGE FROM UPPER 20S
NW TO LOW 40S SE..ROUGHLY 10-12F BELOW MID TO LATE FEB. CLIMATOLOGY.
STRONG SURFACE RIDGE IS MAINTAINED ACROSS THE MID-ATLANTIC REGION
MOST OF THURSDAY AS A NEW STORM SYSTEM BECOMES ORGANIZED IN THE LEE
OF THE ROCKIES AND BEGINS TO LIFT OUT ACROSS THE MIDWEST AS A MAJOR
WINTER STORM WITH POSSIBLE SEVERE WX ACRS PARTS OF TEXAS. COLD AIR
DAMMING WILL BEGIN TO DEVELOP THURSDAY EVENING.NIGHT ALONG THE EAST
COAST FROM THE SAME SURFACE HIGH SLIDING EASTWARD. MEANWHILE FAST
WSW FLOW ALOFT BRINGS MOISTURE RAPIDLY NORTHEASTWARD AND LIKELY
OVERRUNNING THE COOL WEDGE WITH LIKELY P-TYPE FORCAST ISSUES AS
EARLY AS THURSDAY NIGHT.
.LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 328 PM EST SUNDAY...
SURFACE HIGH PRESSURE WILL KEEP THE AREA DRY THURSDAY. OVERRUNNING
MOISTURE FROM THE SOUTH WILL BRING A CHANCE FOR A WINTRY MIX TO THE
AREA THURSDAY NIGHT INTO FRIDAY MORNING. INITIAL PRECIPITATION WILL
FALL INTO DRY AIR AND COULD BEGIN AS A BRIEF PERIOD OF SNOW AND/OR
SLEET. FOR THE MOST PART...RAIN IS EXPECTED THURSDAY NIGHT.
EVAPORATIVE COOLING COULD BRING FREEZING RAIN TO THE BLUE RIDGE AND
TO LOCATIONS NORTH OF HIGHWAY 460 EARLY FRIDAY MORNING. FORECAST
SOUNDINGS CONTINUE TO CARRY A PROFILE FOR FREEZING RAIN...BUT THEY
ARE SLIGHTLY WARMER TODAY AND TIMING WINDOW IS SHORTER. AMOUNTS OF
RAIN/FREEZING RAIN ARE ALSO TRENDING LIGHTER AS GULF COAST
REFLECTION AND CONVECTION MAY ROB OUR MOISTURE. IN KEEPING THE
FORECAST SIMPLE...THURSDAY-FRIDAY FORECAST MAY SOUND WORSE THAN THE
EVENT ITSELF. BUT THEN AGAIN...ANY ICE...NO MATTER HOW LIGHT IS
STILL DANGEROUS.
ASIDE FROM THE P-TYPE ISSUE...MODELS ARE IN GOOD AGREEMENT WITH
PRECIPITATION COMING INTO THE REGION THURSDAY NIGHT AND FRIDAY. RAIN
FALLING INTO THE SURFACE RIDGE WILL ENHANCE IT TO BECOME AN INSITU
WEDGE FRIDAY AND FRIDAY NIGHT. WITH BULK OF THE RAIN TO OUR
SOUTH...FRIDAY COULD JUST BE A LIGHT RAIN/DRIZZLE...GRAY DAY WITH
TEMPERATURES STUCK IN THE 30S. OUTSIDE THE WEDGE...TOWARD
BLUEFIELD...TEMPERATURES COULD JUMP INTO THE LOWER 50S FRIDAY
AFTERNOON.
MEANWHILE...WHILE WE ARE WEDGED IN FRIDAY...A SURFACE REFLECTION
ACROSS THE GULF STATES WILL TRACK EAST OVER THE SOUTHEAST USA FRIDAY
NIGHT AND OFF THE CAROLINA COAST SATURDAY MORNING. THIS WAVE WILL
PUSH WARMER AIR INTO THE REGION AND WITH IT MORE RAIN. WITH THE
TRACK OF THIS REFLECTION ACROSS THE SOUTHEAST...THE BETTER CHANCE
FOR RAIN FRIDAY NIGHT AND SATURDAY MORNING WILL BE ALONG AND EAST OF
THE BLUE RIDGE AND INTO THE PIEDMONT. ONCE THIS WAVE MOVES EAST OF
THE REGION...HIGH PRESSURE IS EXPECTED TO MOVE OVER THE MID
ATLANTIC. THE ECMWF BRINGS ANOTHER WAVE ACROSS THE SOUTHEAST
SATURDAY NIGHT FOR ANOTHER CHANCE OF RAIN. SINCE THE 12Z ECMWF IS
TRENDING TOWARD THE GFS...WILL ONLY HAVE A SLIGHT CHANCE FOR RAIN
SATURDAY AFTERNOON/NIGHT.
FRIDAY LOOKS TO BE THE COLDEST DAY WITH MOST OF THE AREA STUCK IN AN
INSITU WEDGE. ONCE THIS WEDGE BREAKS...TEMPERATURES WILL WARM ABOVE
NORMAL NEXT WEEKEND.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 321 PM EST MONDAY...
THE 12Z ECMWF REMAINS CONSISTENT WITH PREVIOUS RUNS WITH OVERRUNNING
MOISTURE THURSDAY NIGHT...INSITU WEDGE FRIDAY INTO SATURDAY
AND...HIGH PRESSURE SUNDAY AND MONDAY. THE 12Z GFS IS CONSISTENT
THURSDAY NIGHT INTO FRIDAY NIGHT. SATURDAY AND SATURDAY NIGHT...THE
GFS CREATES A VERY COMPLICATED WEATHER PATTERN THAT WOULD BRING
MORE RAIN TO THE AREA. SINCE THIS IS A NEW SCENARIO...I HAVE LOW
POPS IN FOR SATURDAY BUT PRIMARILY WENT WITH THE ECMWF SOLUTION FOR
THIS FORECAST PACKAGE.
SURFACE HIGH PRESSURE WILL BE OVERRUN WITH WARM MOIST AIR THURSDAY
NIGHT INTO FRIDAY. RAIN FALLING OVERNIGHT WILL ENHANCE AN INSITU
WEDGE...KEEPING MOST OF THE AREA DAMP AND CHILLY INTO FRIDAY
POSSIBLY SATURDAY. THIS RAIN WILL ALSO BE FALLING INTO A VERY DRY
AIR MASS. EVAPORATIVE COOLING ALONG EASTERN SLOPES OF THE BLUE RIDGE
AND IN SOME MOUNTAIN VALLEYS SUCH AS THE GREENBRIER...NEW RIVER AND
SOUTHERN SHENANDOAH...COULD HAVE ICE FROM FREEZING RAIN EARLY FRIDAY
MORNING. FORECAST SOUNDINGS CONTINUE TO PROFILE FREEZING RAIN BUT
LIKE YESTERDAY...ARE A LITTLE WARMER AND THE DURATION IS LIMITED TO
4AM-10AM FRIDAY. CONVECTION ACROSS THE SOUTHEASTERN USA MAY ROB SOME
OF OUR MOISTURE...LIMITING ICE ACCRETIONS TO UNDER A TENTH OF AN
INCH ALONG THE BLUE RIDGE AND A GLAZING IN MOUNTAIN VALLEYS.
FRIDAY NIGHT INTO SATURDAY...THE GULF LOW SHOULD TRACK ALONG THE
SOUTHEAST USA...THEN OFF THE CAROLINA COAST. COOL DAMP CONDITIONS
COULD LINGER INTO SATURDAY BUT WARM ENOUGH TO KEEP PRECIPITATION AS
RAIN. THIS LOW MOVES OFF THE COAST SATURDAY NIGHT....BREAKING THE
WEDGE...IF IT IS STILL IN THE REGION. HIGH PRESSURE WILL THEN KEEP
THE REGION DRY UNTIL MONDAY NIGHT WHEN THE NEXT SYSTEM TRACKS TO THE
EAST COAST.
AREAS WITHIN THE WEDGE WILL HAVE A VERY SMALL DIURNAL CURVE IN
TEMPERATURES THURSDAY NIGHT INTO SATURDAY. TEMPERATURES COULD BE
STUCK IN THE 30S IN THE WEDGE WHILE MID 40S TO LOWER 50S ARE
POSSIBLE OUTSIDE THE WEDGE. TEMPERATURES ARE EXPECTED TO WARM ABOVE
NORMAL SUNDAY AND MONDAY.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
AS OF 555 PM EST MONDAY...
VFR CONDITIONS WILL CONTINUE THIS EVENING WITH JUST SOME INCREASE
IN MID AND HIGH CLOUDS THROUGH ABOUT MIDNIGHT. WINDS ALOFT WILL BE
ON THE INCREASE AS WELL AFTER SUNSET BUT THINK WILL BE JUST BELOW
LLWS CRITERIA SO WONT INCLUDE THIS EVENING. HOWEVER THE LOW LEVEL
JET ALONG WITH DEEPER MOISTURE SHOULD INCREASE QUICKLY AS THE
FRONT APPROACHES AND WE WILL SEE SOME PCPN DEVELOP IN THE EARLY
MORNING HOURS FROM WEST TO EAST. PTYPE WILL BE A BIT PROBLEMATIC
AS MODEL SOUNDINGS INDICATE MOSTLY SNOW AT THE ONSET FOR KLWB...
RAIN FOR KDAN...AND A WINTRY MIX FOR SITES IN BETWEEN. APPEARS
CIGS MAY STAY VFR UNTIL ABOUT AN HOUR OR TWO BEFORE THE FAST
MOVING AXIS OF PRECIP ARRIVES...THEN QUICKLY LOWER INTO MVFR
LEVELS WEST OF THE BLUE RIDGE BEFORE DAWN...AND OUT EAST AROUND
12Z/7AM. LOOKS LIKE MOST SPOTS WILL WARM ENOUGH TO CAUSE A CHANGE
TO JUST -RA BY MID MORNING EXCEPT VALLEYS WHERE TRAPPED COLD AIR
COULD MAKE FOR SOME LINGERING LIGHT MIX A WHILE LONGER. THIS BASED
ON A SCENARIO WHERE THE PRECIP IS AS MUCH AS 2 TO 3 HOURS FASTER
THAN THE FASTEST MODEL SOLUTION GIVEN TENDENCY OF THESE EVENTS TO
ROCKET EAST MUCH FASTER THAN PROGGED UNDER THE NOSE OF THE JET
ALOFT.
OVERALL LIGHT SURFACE WINDS THIS EVENING WILL START TO INCREASE
ESPCLY ACROSS THE HIGHER ELEVATIONS INCLUDING KBLF WHERE EXPECT
SOUTHERLY GUSTS TO OVER 20 KTS BY MIDNIGHT...AND PERHAPS 30+ KTS
RIGHT AHEAD OF THE PRECIP SHIELD TOWARD DAYBREAK. ELSW VERY
STRONG JET ALOFT WILL BE LIMITED IN MIXING DOWN AS WILL SEE QUITE
A GRADIENT WITHIN THE LOWEST FEW THOUSAND FEET AS THE 50-60 KT JET
SHIFTS EAST. THUS WILL INCLUDE A FEW HOURS OF LLWS AT ALL OTHER
LOCATIONS UNTIL THINGS START TO MIX OUT BY LATE MORNING AND ESPCLY
DURING THE AFTERNOON WHEN TRAJECTORIES TURN MORE WESTERLY AND
STRONGER GUSTS OF 25-30+ KTS REACH THE SURFACE. OTRW THINK SIG
PRECIP WILL END BY 20Z/3PM MOST SPOTS WITH ONLY SOME LINGERING -RA
OR SHOWERS ACROSS THE NW INTO EARLY TUESDAY EVENING.
.EXTENDED AVIATION DISCUSSION...
GUSTY WINDS WILL CONTINUE BEHIND THE FRONT TUESDAY NIGHT INTO
WEDNESDAY...WITH ENOUGH SYNOPTIC MOISTURE LINGERING TO KEEP
CLOUDS AROUND FOR KLWB AND LIKELY KBLF AS WELL. HIGH PRESSURE WILL
THEN BUILD IN THURSDAY ALLOWING FOR VFR WEATHER. ANOTHER FRONTAL
SYSTEM WITH THE NEXT ROUND OF PRECIP WILL ARRIVE THURSDAY NIGHT
AND FRIDAY WITH MORE MVFR/IFR CONDITIONS POSSIBLE. THIS MAY BE
FOLLOWED BY ANOTHER IMPULSE HEADING NE FROM THE GULF COAST AREA
ALONG THE RESIDUAL FRONT ON SATURDAY WHICH MAY LINGER LOW FLYING
CONDITIONS INTO SATURDAY NIGHT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM 3 AM TO 10 AM EST TUESDAY FOR
VAZ007-009>020-022>024.
NC...WINTER WEATHER ADVISORY FROM 3 AM TO 10 AM EST TUESDAY FOR
NCZ001-002-018.
WV...WINTER WEATHER ADVISORY FROM 3 AM TO 10 AM EST TUESDAY FOR
WVZ042>045.
&&
$$
SYNOPSIS...WP
NEAR TERM...JH/WP
SHORT TERM...PC
LONG TERM...RCS
AVIATION...JH/MBS/RAB
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1024 AM EST SUN FEB 17 2013
.SYNOPSIS...
HIGH PRESSURE IS GOING TO MOVE EAST AND COVER THE AREA BY TONIGHT.
THIS HIGH LINGERS INTO MONDAY...SHIFTING OFF THE COAST MONDAY
AFTERNOON. A COLD FRONT WILL MOVE INTO THE AREA EARLY TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1010 AM EST SUNDAY...
WIND CHILL ADVISORY WAS ALLOWED TO EXPIRE FOR THE SOUTHWEST VA/SRN
WV MTNS THIS MORNING. WIND CHILLS IN MOST PLACES ARE WARMER THAN 5
BELOW OUTSIDE THE HIGHEST PEAKS.
DEALING WITH A SHORTWAVE THAT IS MOVING NORTHEAST OVER THE AREA
THIS MORNING. MOST OF THE SNOW SHOWERS HAVE TAPERED OFF EAST OF
THE UPSLOPE ZONES. THINK THE NAM/LOCAL WRF USUALLY DO A BETTER JOB
OF LEAVING SNOW SHOWERS IN LONGER AND WILL SEE SNOW SHOWERS
LINGERING TIL ABOUT EARLY AFTERNOON OVER THE NC MTNS...BEFORE
ENDING. HOWEVER...DO NOT FORESEE ANY ACCUMULATIONS ABOVE AN INCH
SO WILL MORE THAN LIKELY ALLOW THE ADVISORY FOR THE HIGHER
ELEVATIONS TO EXPIRE AT NOON. THERE WILL BE SOME BANDING STILL
GOING ON THROUGH THE AFTERNOON NORTH OF A RICHLANDS TO BURKES
GARDEN LINE...THINKING THE HIGHER SLOPES OF MERCER TO GREENBRIER
RECEIVE AT LEAST ANOTHER INCH IF NOT MORE BEFORE MOISTURE
DIMINISHES AROUND DUSK.
TEMPERATURES/WIND CHILLS ARE GOING TO STAY VERY COLD TODAY AND DO
NOT FORESEE THE HIGHER ELEVATIONS MAKING IT OUT OF THE LOWER
TEENS. MOST AREAS WEST OF THE BLUE RIDGE SHOULD REACH THE
20S...WHILE THE EAST GETS TO AT LEAST FREEZING. SNOW COVER EAST OF
LYH MAY HOLD TEMPS DOWN THERE SOME.
LATEST RAP AND LOCAL WRF CONTINUED TO SHOW BANDS OF SNOW SHOWERS
ACROSS THE MOUNTAINS...AND FOR A FEW HOURS THIS MORNING. SPILLING
INTO FRANKLIN...HENRY AND PATRICK COUNTIES. VISIBILITIES WERE
DROPPING TO AROUND A MILE UNDER THE HEAVY SNOW BANDS. HAVE SPREAD
THE FORECAST FOR ACCUMULATING SNOW LATER INTO THE MORNING FOR THE
WESTERN UPSLOPE COUNTIES AND THE NEW RIVER VALLEY.
BUFKIT SHOWED THE POTENTIAL FOR WIND GUSTS AROUND 40 KNOTS AT TNB
BUT ONLY 30 KNOTS FOR MOST OTHER LOCATIONS. NO WIND ADVISORY
PLANNED FOR NOW. JUST HIGHLIGHTED WINDS IN THE ONGOING WINTER
WEATHER ADVISORY.
PREVIOUS VALID DISCUSSION...
ONCE THE SUN SETS...WIND SPEEDS ARE EXPECTED TO DROP OFF TO LESS
THAN 10 MPH SO EVEN THOUGH OVERNIGHT LOW TEMPERATURES WILL AGAIN
BE IN THE SINGLE DIGITS TO AROUND 20...THE WIND CHILL WILL NOT BE
A FACTOR.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
AS OF 330 AM EST SUNDAY...
ON MONDAY...WE WILL HAVE ONE DRY AND MILDER...AND LESS WINDY DAY AS
HIGH PRESSURE BUILDS OVER THE REGION. WE EXPECTING HIGHS IN THE MID
TO UPPER 40S ACROSS THE MOUNTAINS WITH UPPER 40S EAST OF THE CREST
OF THE BLUE RIDGE.
MONDAY NIGHT THROUGH TUESDAY...A QUICK MOVING COLD FRONT WILL
APPROACH AND THEN CROSS THE REGION. WE WILL FIRST EXPERIENCE
INCREASING CLOUD COVER MONDAY EVENING...AND THEN PRECIPITATION WILL
MOVE INTO THE REGION FROM THE WEST AFTER MIDNIGHT AHEAD OF THE COLD
FRONT. THE PRECIPITATION WILL BE ACCOMPANIED BY A WARM NOSE ALOFT
OVER A MIX OF ABOVE AND BELOW TEMPERATURES AT THE SURFACE. MODEL
GUIDANCE HAS TRENDED COLDER WITH THE MAGNITUDE OF THE WARM NOSE. WE
ARE SEEING A TREND TOWARDS MORE SNOW AND SLEET ACROSS THE MOUNTAINS
AND THE NORTHERN THIRD OF THE FORECAST AREA LATE MONDAY NIGHT INTO
EARLY TUESDAY MORNING. AFTER ROUGHLY 9 OR 10 AM
TUESDAY...TEMPERATURES WILL BE MILD ENOUGH FOR MOST OF THE AREA TO
RECEIVE RAIN. THERE STILL MAY BE SOME SNOW IN WESTERN GREENBRIER
COUNTY WV THROUGH THE DAYTIME TUESDAY. BY TUESDAY AFTERNOON...THE
COLD FRONT WILL BE HEADING EAST OF THE FORECAST AREA AND THE
PRECIPITATION WILL BEGIN TO BECOME CONFINED TO THE UPSLOPE REGIONS
OF SOUTHEAST WEST VIRGINIA. AS WE HEAD INTO TUESDAY NIGHT...THIS
PRECIPITATION WILL QUICKLY TRANSITION INTO SNOW SHOWERS...BUT
TREND TOWARDS DECREASING COVERAGE THROUGH THE NIGHT. THE REMAINDER
OF THE FORECAST AREA WILL BE PRECIPITATION FREE.
WE ARE STILL CONCERNED ABOUT GUSTY/DAMAGING WINDS AHEAD OF THE FRONT
ON TUESDAY AND THEN BEHIND THE FRONT TUESDAY NIGHT. MODEL GUIDANCE
PLACES A SOUTHWEST 850 MB JET AROUND 60 TO 65 KTS JUST IN ADVANCE OF
THE FRONT. SOME STRONGER GUSTS MAY BE ABLE TO ACCOMPANY THE HEAVIER
SHOWERS TO THE SURFACE. TUESDAY NIGHT...NORTHWEST 850 MB WINDS OF 50
KTS ARE EXPECTED BY MIDNIGHT...AND 50 TO 60 KTS ARE EXPECTED BY
SUNRISE WEDNESDAY. CONFIDENCE IS GROWING FOR THE POTENTIAL FOR AT
LEAST A WIND ADVISORY TUESDAY AND THEN AGAIN TUESDAY NIGHT INTO
EARLY WEDNESDAY.
WEDNESDAY INTO WEDNESDAY NIGHT...A DRY FORECAST IS EXPECTED AND
WINDS WILL EXPERIENCE A GRADUAL DECREASE AS THE CENTER OF HIGH
PRESSURE DRAWS CLOSER.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 320 PM EST SATURDAY...
BY THURSDAY AFTERNOON...AN INVERTED TROUGH WILL DEVELOP ACROSS
EASTERN KENTUCKY AND WEST VIRGINIA. THIS WILL ALLOW THE WINDS TO
BECOME EASTERLY WITH UNIFORM TEMPERATURES IN THE 40S ACROSS THE
AREA.
A WARM FRONT WILL OVERRUN THIS SURFACE RIDGE THURSDAY NIGHT WITH
PRECIPITATION TRACKING FROM SOUTHWEST TO NORTHEAST. THIS
PRECIPITATION WILL BE FALLING INTO DRY AIR WITH DEW POINTS IN THE
UPPER TEENS TO MID 20S. INITIAL P-TYPE WILL BE A BRIEF PERIOD OF
SLEET FOLLOWED BY RAIN AND FREEZING RAIN. FORECAST SOUNDINGS
CONTINUES TO SUPPORT FREEZING RAIN FRIDAY MORNING. CHANCES OF
FREEZING RAIN ARE MORESO ALONG THE EASTERN SLOPES OF THE BLUE
RIDGE AND POSSIBLY ACROSS THE GREENBRIER AND SOUTH SHENANDOAH
VALLEY. CONVECTION TRACKING ACROSS THE SOUTHEASTERN US MAY KEEP
RAIN/ICE AMOUNTS LOWER THAN CURRENTLY FORECASTED BY THE MODELS.
THE GFS/ECMWF HAS A QUARTER TO A HALF INCH OF LIQUID WITH THIS
SYSTEM.
BULK OF THE PRECIPITATION WILL MOVE EAST FRIDAY
AFTERNOON...HOWEVER...THE INSITU WEDGE WITH COLD...GRAY...DAMP
CONDITIONS MAY LINGER ACROSS THE PIEDMONT INTO FRIDAY NIGHT. AS
THE WEDGE BREAKS...TEMPERATURES WILL WARM ABOVE FREEZING. FOG
COULD THEN BECOME A PROBLEM FRIDAY NIGHT INTO SATURDAY MORNING. BY
SATURDAY AFTERNOON...THE WINDS BECOME WESTERLY WITH TEMPERATURES
POSSIBLY WARMING ABOVE NORMAL.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
AS OF 655 AM EST SUNDAY...
NORTHWEST WINDS WILL CONTINUE TO PRODUCE BANDS OF SNOW SHOWERS
OVER THE MOUNTAINS. WITHIN THE BANDS OF SNOW VISIBILITIES DROP TO
LESS THAN ONE MILE AND CEILINGS DROP BELOW 1000 FT AGL...SO EXPECT
THESE CONDITIONS IF ONE OF THESE BANDS TRACKS DIRECTLY OVER AN
AIRPORT. BLF AND LWB HAVE THE GREATEST CHANCE FOR SNOW THIS
MORNING...AND THE CHANCE AT ROA AND BCB WILL BE LOWER.
BUFKIT SHOULD WIND GUSTS TODAY REACHING 30 TO 40 KNOTS IN THE
MOUNTAINS...ESPECIALLY AT HIGHER ELEVATIONS ALONG THE SOUTHERN
BLUE RIDGE. EAST OF THE BLUE RIDGE...INCLUDING AT ROA...PLAN
ON WIND GUSTS MAINLY FROM 20 TO 30 KNOTS.
HIGH PRESSURE WILL BUILD IN FOR TONIGHT AND MONDAY MORNING. AFTER
SUNSET WINDS WILL DIMINISH AND THE SKY WILL BE CLEAR. HIGH
CONFIDENCE FOR VFR CONDITIONS THROUGH THE END OF THE DAY ON
MONDAY.
A COLD FRONT WILL APPROACH THE AREA EARLY TUESDAY...WITH A MIX OF
WINTER PRECIPITATION POSSIBLE IN THE MOUNTAINS STARTING LATE
MONDAY NIGHT. EXPECT IFR CONDITIONS WITH THIS PRECIPITATION AND
STRONGER WINDS AHEAD OF THE FRONT ON TUESDAY. GUSTY WINDS WILL
CONTINUE BEHIND THE FRONT ON TUESDAY NIGHT AND WEDNESDAY. HIGH
PRESSURE WILL THEN BUILD IN FOR THURSDAY ALLOWING FOR VFR WEATHER.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NCZ001-018.
WV...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
WVZ045.
&&
$$
SYNOPSIS...AMS/WP
NEAR TERM...AMS/WP
SHORT TERM...DS
LONG TERM...RCS
AVIATION...AMS/DS/JH
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
703 AM EST SUN FEB 17 2013
.SYNOPSIS...
LOW PRESSURE WAS WELL OFF THE NEW JERSEY COAST THIS MORNING.
HIGH PRESSURE WAS CENTERED OVER MISSISSIPPI AND ALABAMA. THIS HIGH
WILL COVER MUCH OF THE MID ATLANTIC REGION AND SOUTHEAST UNITED
STATES THROUGH MONDAY MORNING. A COLD FRONT WILL MOVE INTO THE
AREA EARLY TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 440 AM EST SUNDAY...
LATEST RAP AND LOCAL WRF CONTINUED TO SHOW BANDS OF SNOW SHOWERS
ACROSS THE MOUNTAINS...AND FOR A FEW HOURS THIS MORNING. SPILLING
INTO FRANKLIN...HENRY AND PATRICK COUNTIES. VISIBILITIES WERE
DROPPING TO AROUND A MILE UNDER THE HEAVY SNOW BANDS. HAVE SPREAD
THE FORECAST FOR ACCUMULATING SNOW LATER INTO THE MORNING FOR THE
WESTERN UPSLOPE COUNTIES AND THE NEW RIVER VALLEY.
BUFKIT SHOWED THE POTENTIAL FOR WIND GUSTS AROUND 40 KNOTS AT TNB
BUT ONLY 30 KNOTS FOR MOST OTHER LOCATIONS. NO WIND ADVISORY
PLANNED FOR NOW. JUST HIGHLIGHTED WINDS IN THE ONGOING WINTER
WEATHER ADVISORY.
850 MB TEMPERATURES THIS MORNING SHOULD BE IN THE -14 TO -18
DEGREE CELCIUS RANGE. HAVE ISSUED A WIND CHILL ADVISORY FROM
TAZEWELL COUNTY INTO GRAYSON COUNTY WHERE WINDS CHILLS WILL MEET
CRITERIA THIS MORNING.
SURFACE HIGH PRESSURE WILL BUILD OVER THE SOUTHEAST UNITED STATES
THIS AFTERNOON. THIS WILL RESULT IN DIMINISHING WINDS AND
DECREASING COVERAGE OF SNOW SHOWERS. ONCE THE SUN SETS...WIND
SPEEDS ARE EXPECTED TO DROP OFF TO LESS THAN 10 MPH SO EVEN THOUGH
OVERNIGHT LOW TEMPERATURES WILL AGAIN BE IN THE SINGLE DIGITS TO
AROUND 20...THE WIND CHILL WILL NOT BE A FACTOR.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
AS OF 330 AM EST SUNDAY...
ON MONDAY...WE WILL HAVE ONE DRY AND MILDER...AND LESS WINDY DAY AS
HIGH PRESSURE BUILDS OVER THE REGION. WE EXPECTING HIGHS IN THE MID
TO UPPER 40S ACROSS THE MOUNTAINS WITH UPPER 40S EAST OF THE CREST
OF THE BLUE RIDGE.
MONDAY NIGHT THROUGH TUESDAY...A QUICK MOVING COLD FRONT WILL
APPROACH AND THEN CROSS THE REGION. WE WILL FIRST EXPERIENCE
INCREASING CLOUD COVER MONDAY EVENING...AND THEN PRECIPITATION WILL
MOVE INTO THE REGION FROM THE WEST AFTER MIDNIGHT AHEAD OF THE COLD
FRONT. THE PRECIPITATION WILL BE ACCOMPANIED BY A WARM NOSE ALOFT
OVER A MIX OF ABOVE AND BELOW TEMPERATURES AT THE SURFACE. MODEL
GUIDANCE HAS TRENDED COLDER WITH THE MAGNITUDE OF THE WARM NOSE. WE
ARE SEEING A TREND TOWARDS MORE SNOW AND SLEET ACROSS THE MOUNTAINS
AND THE NORTHERN THIRD OF THE FORECAST AREA LATE MONDAY NIGHT INTO
EARLY TUESDAY MORNING. AFTER ROUGHLY 9 OR 10 AM
TUESDAY...TEMPERATURES WILL BE MILD ENOUGH FOR MOST OF THE AREA TO
RECEIVE RAIN. THERE STILL MAY BE SOME SNOW IN WESTERN GREENBRIER
COUNTY WV THROUGH THE DAYTIME TUESDAY. BY TUESDAY AFTERNOON...THE
COLD FRONT WILL BE HEADING EAST OF THE FORECAST AREA AND THE
PRECIPITATION WILL BEGIN TO BECOME CONFINED TO THE UPSLOPE REGIONS
OF SOUTHEAST WEST VIRGINIA. AS WE HEAD INTO TUESDAY NIGHT...THIS
PRECIPITATION WILL QUICKLY TRANSITION INTO SNOW SHOWERS...BUT
TREND TOWARDS DECREASING COVERAGE THROUGH THE NIGHT. THE REMAINDER
OF THE FORECAST AREA WILL BE PRECIPITATION FREE.
WE ARE STILL CONCERNED ABOUT GUSTY/DAMAGING WINDS AHEAD OF THE FRONT
ON TUESDAY AND THEN BEHIND THE FRONT TUESDAY NIGHT. MODEL GUIDANCE
PLACES A SOUTHWEST 850 MB JET AROUND 60 TO 65 KTS JUST IN ADVANCE OF
THE FRONT. SOME STRONGER GUSTS MAY BE ABLE TO ACCOMPANY THE HEAVIER
SHOWERS TO THE SURFACE. TUESDAY NIGHT...NORTHWEST 850 MB WINDS OF 50
KTS ARE EXPECTED BY MIDNIGHT...AND 50 TO 60 KTS ARE EXPECTED BY
SUNRISE WEDNESDAY. CONFIDENCE IS GROWING FOR THE POTENTIAL FOR AT
LEAST A WIND ADVISORY TUESDAY AND THEN AGAIN TUESDAY NIGHT INTO
EARLY WEDNESDAY.
WEDNESDAY INTO WEDNESDAY NIGHT...A DRY FORECAST IS EXPECTED AND
WINDS WILL EXPERIENCE A GRADUAL DECREASE AS THE CENTER OF HIGH
PRESSURE DRAWS CLOSER.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 320 PM EST SATURDAY...
BY THURSDAY AFTERNOON...AN INVERTED TROUGH WILL DEVELOP ACROSS
EASTERN KENTUCKY AND WEST VIRGINIA. THIS WILL ALLOW THE WINDS TO
BECOME EASTERLY WITH UNIFORM TEMPERATURES IN THE 40S ACROSS THE
AREA.
A WARM FRONT WILL OVERRUN THIS SURFACE RIDGE THURSDAY NIGHT WITH
PRECIPITATION TRACKING FROM SOUTHWEST TO NORTHEAST. THIS
PRECIPITATION WILL BE FALLING INTO DRY AIR WITH DEW POINTS IN THE
UPPER TEENS TO MID 20S. INITIAL P-TYPE WILL BE A BRIEF PERIOD OF
SLEET FOLLOWED BY RAIN AND FREEZING RAIN. FORECAST SOUNDINGS
CONTINUES TO SUPPORT FREEZING RAIN FRIDAY MORNING. CHANCES OF
FREEZING RAIN ARE MORESO ALONG THE EASTERN SLOPES OF THE BLUE
RIDGE AND POSSIBLY ACROSS THE GREENBRIER AND SOUTH SHENANDOAH
VALLEY. CONVECTION TRACKING ACROSS THE SOUTHEASTERN US MAY KEEP
RAIN/ICE AMOUNTS LOWER THAN CURRENTLY FORECASTED BY THE MODELS.
THE GFS/ECMWF HAS A QUARTER TO A HALF INCH OF LIQUID WITH THIS
SYSTEM.
BULK OF THE PRECIPITATION WILL MOVE EAST FRIDAY
AFTERNOON...HOWEVER...THE INSITU WEDGE WITH COLD...GRAY...DAMP
CONDITIONS MAY LINGER ACROSS THE PIEDMONT INTO FRIDAY NIGHT. AS
THE WEDGE BREAKS...TEMPERATURES WILL WARM ABOVE FREEZING. FOG
COULD THEN BECOME A PROBLEM FRIDAY NIGHT INTO SATURDAY MORNING. BY
SATURDAY AFTERNOON...THE WINDS BECOME WESTERLY WITH TEMPERATURES
POSSIBLY WARMING ABOVE NORMAL.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AS OF 655 AM EST SUNDAY...
NORTHWEST WINDS WILL CONTINUE TO PRODUCE BANDS OF SNOW SHOWERS
OVER THE MOUNTAINS. WITHIN THE BANDS OF SNOW VISIBILITIES DROP TO
LESS THAN ONE MILE AND CEILINGS DROP BELOW 1000 FT AGL...SO EXPECT
THESE CONDITIONS IF ONE OF THESE BANDS TRACKS DIRECTLY OVER AN
AIRPORT. BLF AND LWB HAVE THE GREATEST CHANCE FOR SNOW THIS
MORNING...AND THE CHANCE AT ROA AND BCB WILL BE LOWER.
BUFKIT SHOULD WIND GUSTS TODAY REACHING 30 TO 40 KNOTS IN THE
MOUNTAINS...ESPECIALLY AT HIGHER ELEVATIONS ALONG THE SOUTHERN
BLUE RIDGE. EAST OF THE BLUE RIDGE...INCLUDING AT ROA...PLAN
ON WIND GUSTS MAINLY FROM 20 TO 30 KNOTS.
HIGH PRESSURE WILL BUILD IN FOR TONIGHT AND MONDAY MORNING. AFTER
SUNSET WINDS WILL DIMINISH AND THE SKY WILL BE CLEAR. HIGH
CONFIDENCE FOR VFR CONDITIONS THROUGH THE END OF THE DAY ON
MONDAY.
A COLD FRONT WILL APPROACH THE AREA EARLY TUESDAY...WITH A MIX OF
WINTER PRECIPITATION POSSIBLE IN THE MOUNTAINS STARTING LATE
MONDAY NIGHT. EXPECT IFR CONDITIONS WITH THIS PRECIPITATION AND
STRONGER WINDS AHEAD OF THE FRONT ON TUESDAY. GUSTY WINDS WILL
CONTINUE BEHIND THE FRONT ON TUESDAY NIGHT AND WEDNESDAY. HIGH
PRESSURE WILL THEN BUILD IN FOR THURSDAY ALLOWING FOR VFR WEATHER.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ007-
009-010-012-015.
NC...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NCZ001-018.
WV...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
WVZ045.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...DS
LONG TERM...RCS
AVIATION...AMS/DS/JH
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
459 AM EST SUN FEB 17 2013
.SYNOPSIS...
LOW PRESSURE WAS WELL OFF THE NEW JERSEY COAST THIS MORNING.
HIGH PRESSURE WAS CENTERED OVER MISSISSIPPI AND ALABAMA. THIS HIGH
WILL COVER MUCH OF THE MID ATLANTIC REGION AND SOUTHEAST UNITED
STATES THROUGH MONDAY MORNING. A COLD FRONT WILL MOVE INTO THE
AREA EARLY TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 440 AM EST SUNDAY...
LATEST RAP AND LOCAL WRF CONTINUED TO SHOW BANDS OF SNOW SHOWERS
ACROSS THE MOUNTAINS...AND FOR A FEW HOURS THIS MORNING. SPILLING
INTO FRANKLIN...HENRY AND PATRICK COUNTIES. VISIBILITIES WERE
DROPPING TO AROUND A MILE UNDER THE HEAVY SNOW BANDS. HAVE SPREAD
THE FORECAST FOR ACCUMULATING SNOW LATER INTO THE MORNING FOR THE
WESTERN UPSLOPE COUNTIES AND THE NEW RIVER VALLEY.
BUFKIT SHOWED THE POTENTIAL FOR WIND GUSTS AROUND 40 KNOTS AT TNB
BUT ONLY 30 KNOTS FOR MOST OTHER LOCATIONS. NO WIND ADVISORY
PLANNED FOR NOW. JUST HIGHLIGHTED WINDS IN THE ONGOING WINTER
WEATHER ADVISORY.
850 MB TEMPERATURES THIS MORNING SHOULD BE IN THE -14 TO -18
DEGREE CELCIUS RANGE. HAVE ISSUED A WIND CHILL ADVISORY FROM
TAZEWELL COUNTY INTO GRAYSON COUNTY WHERE WINDS CHILLS WILL MEET
CRITERIA THIS MORNING.
SURFACE HIGH PRESSURE WILL BUILD OVER THE SOUTHEAST UNITED STATES
THIS AFTERNOON. THIS WILL RESULT IN DIMINISHING WINDS AND
DECREASING COVERAGE OF SNOW SHOWERS. ONCE THE SUN SETS...WIND
SPEEDS ARE EXPECTED TO DROP OFF TO LESS THAN 10 MPH SO EVEN THOUGH
OVERNIGHT LOW TEMPERATURES WILL AGAIN BE IN THE SINGLE DIGITS TO
AROUND 20...THE WIND CHILL WILL NOT BE A FACTOR.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
AS OF 330 AM EST SUNDAY...
ON MONDAY...WE WILL HAVE ONE DRY AND MILDER...AND LESS WINDY DAY AS
HIGH PRESSURE BUILDS OVER THE REGION. WE EXPECTING HIGHS IN THE MID
TO UPPER 40S ACROSS THE MOUNTAINS WITH UPPER 40S EAST OF THE CREST
OF THE BLUE RIDGE.
MONDAY NIGHT THROUGH TUESDAY...A QUICK MOVING COLD FRONT WILL
APPROACH AND THEN CROSS THE REGION. WE WILL FIRST EXPERIENCE
INCREASING CLOUD COVER MONDAY EVENING...AND THEN PRECIPITATION WILL
MOVE INTO THE REGION FROM THE WEST AFTER MIDNIGHT AHEAD OF THE COLD
FRONT. THE PRECIPITATION WILL BE ACCOMPANIED BY A WARM NOSE ALOFT
OVER A MIX OF ABOVE AND BELOW TEMPERATURES AT THE SURFACE. MODEL
GUIDANCE HAS TRENDED COLDER WITH THE MAGNITUDE OF THE WARM NOSE. WE
ARE SEEING A TREND TOWARDS MORE SNOW AND SLEET ACROSS THE MOUNTAINS
AND THE NORTHERN THIRD OF THE FORECAST AREA LATE MONDAY NIGHT INTO
EARLY TUESDAY MORNING. AFTER ROUGHLY 9 OR 10 AM
TUESDAY...TEMPERATURES WILL BE MILD ENOUGH FOR MOST OF THE AREA TO
RECEIVE RAIN. THERE STILL MAY BE SOME SNOW IN WESTERN GREENBRIER
COUNTY WV THROUGH THE DAYTIME TUESDAY. BY TUESDAY AFTERNOON...THE
COLD FRONT WILL BE HEADING EAST OF THE FORECAST AREA AND THE
PRECIPITATION WILL BEGIN TO BECOME CONFINED TO THE UPSLOPE REGIONS
OF SOUTHEAST WEST VIRGINIA. AS WE HEAD INTO TUESDAY NIGHT...THIS
PRECIPITATION WILL QUICKLY TRANSITION INTO SNOW SHOWERS...BUT
TREND TOWARDS DECREASING COVERAGE THROUGH THE NIGHT. THE REMAINDER
OF THE FORECAST AREA WILL BE PRECIPITATION FREE.
WE ARE STILL CONCERNED ABOUT GUSTY/DAMAGING WINDS AHEAD OF THE FRONT
ON TUESDAY AND THEN BEHIND THE FRONT TUESDAY NIGHT. MODEL GUIDANCE
PLACES A SOUTHWEST 850 MB JET AROUND 60 TO 65 KTS JUST IN ADVANCE OF
THE FRONT. SOME STRONGER GUSTS MAY BE ABLE TO ACCOMPANY THE HEAVIER
SHOWERS TO THE SURFACE. TUESDAY NIGHT...NORTHWEST 850 MB WINDS OF 50
KTS ARE EXPECTED BY MIDNIGHT...AND 50 TO 60 KTS ARE EXPECTED BY
SUNRISE WEDNESDAY. CONFIDENCE IS GROWING FOR THE POTENTIAL FOR AT
LEAST A WIND ADVISORY TUESDAY AND THEN AGAIN TUESDAY NIGHT INTO
EARLY WEDNESDAY.
WEDNESDAY INTO WEDNESDAY NIGHT...A DRY FORECAST IS EXPECTED AND
WINDS WILL EXPERIENCE A GRADUAL DECREASE AS THE CENTER OF HIGH
PRESSURE DRAWS CLOSER.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 320 PM EST SATURDAY...
BY THURSDAY AFTERNOON...AN INVERTED TROUGH WILL DEVELOP ACROSS
EASTERN KENTUCKY AND WEST VIRGINIA. THIS WILL ALLOW THE WINDS TO
BECOME EASTERLY WITH UNIFORM TEMPERATURES IN THE 40S ACROSS THE
AREA.
A WARM FRONT WILL OVERRUN THIS SURFACE RIDGE THURSDAY NIGHT WITH
PRECIPITATION TRACKING FROM SOUTHWEST TO NORTHEAST. THIS
PRECIPITATION WILL BE FALLING INTO DRY AIR WITH DEW POINTS IN THE
UPPER TEENS TO MID 20S. INITIAL P-TYPE WILL BE A BRIEF PERIOD OF
SLEET FOLLOWED BY RAIN AND FREEZING RAIN. FORECAST SOUNDINGS
CONTINUES TO SUPPORT FREEZING RAIN FRIDAY MORNING. CHANCES OF
FREEZING RAIN ARE MORESO ALONG THE EASTERN SLOPES OF THE BLUE
RIDGE AND POSSIBLY ACROSS THE GREENBRIER AND SOUTH SHENANDOAH
VALLEY. CONVECTION TRACKING ACROSS THE SOUTHEASTERN US MAY KEEP
RAIN/ICE AMOUNTS LOWER THAN CURRENTLY FORECASTED BY THE MODELS.
THE GFS/ECMWF HAS A QUARTER TO A HALF INCH OF LIQUID WITH THIS
SYSTEM.
BULK OF THE PRECIPITATION WILL MOVE EAST FRIDAY
AFTERNOON...HOWEVER...THE INSITU WEDGE WITH COLD...GRAY...DAMP
CONDITIONS MAY LINGER ACROSS THE PIEDMONT INTO FRIDAY NIGHT. AS
THE WEDGE BREAKS...TEMPERATURES WILL WARM ABOVE FREEZING. FOG
COULD THEN BECOME A PROBLEM FRIDAY NIGHT INTO SATURDAY MORNING. BY
SATURDAY AFTERNOON...THE WINDS BECOME WESTERLY WITH TEMPERATURES
POSSIBLY WARMING ABOVE NORMAL.
&&
.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
AS OF 1205 AM EST SUNDAY...
NORTHWEST FLOW IS EXPECTED TO CONTINUE ACROSS THE REGION TONIGHT
THROUGH SUNDAY. BANDS OF SNOW SHOWERS ARE OCCURRING ACROSS THE
MOUNTAINS...AND THESE WILL CONTINUE...BUT TREND TOWARD DECREASING
COVERAGE AFTER SUNRISE. LOCALIZED IFR CONDITIONS ARE EXPECTED
WITHIN THE HEAVIER BANDS...WITH VFR CONDITIONS THE NORM ELSEWHERE.
SURFACE GUSTS IN THE MOUNTAINS WILL INCREASE TO AROUND 25 KTS BY
12Z/7AM WITH READINGS AROUND 30-35 KTS NEAR THE CREST OF THE BLUE
RIDGE BY 15Z/10AM. WINDS WILL GRADUALLY DECREASE DURING SUNDAY
AFTERNOON...BUT THE NOTABLE DECREASE WILL OCCUR AROUND SUNSET AS
BOTH THE NOCTURNAL INVERSION DEVELOPS AND WINDS ALOFT START TO
DECREASE IN SPEED.
HIGH PRESSURE WILL BUILD IN FOR SUNDAY NIGHT AND MONDAY...BUT HE
BREAK WILL BE SHORT LIVED AS LOW PRESSURE MOVING INTO THE GREAT
LAKES REGION WILL PUSH A COLD FRONT THROUGH THE AREA ON
TUESDAY...WITH PCPN AHEAD OF THE FRONT MAKING ITS WAY INTO THE TAF
SITES LATE MONDAY NIGHT. EXPECT IFR CONDITIONS WITH PCPN AND WINDY
CONDITIONS WITH FROPA ON TUESDAY AND WINDS CONTINUING BEHIND THE
FRONT ON WEDNESDAY. HIGH PRESSURE WILL THEN BUILD IN FOR THURSDAY
ALLOWING A BRIEF SPELL OF VFR.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ007-
009-010-012-015.
NC...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NCZ001-018.
WV...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
WVZ045.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...DS
LONG TERM...RCS
AVIATION...AMS/DS/JH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
636 PM CST MON FEB 18 2013
.SHORT TERM...TONIGHT
635 PM CST MON FEB 18 2013
A FEW ISSUES TO DEAL WITH AS DESCRIBED BELOW.
1. TEMPERATURES HAVE BEEN FALLING A LITTLE QUICKER THAN PREVIOUSLY
EXPECTED...WITH THE STRONG NORTHWEST WINDS DRIVING IN ARCTIC AIR
FASTER FROM THE DAKOTAS. ADJUSTED THE HOURLY TEMPERATURE TREND A
FEW TIMES TO ACCOUNT FOR THIS. SO FAR...LOW TEMPERATURES STILL
SEEM ON TRACK.
2. COMBINATION OF THE RECENT SNOW MELTING ON WARM ROADWAYS...ALONG
WITH THE ARCTIC AIR FLOWING IN AND SUN GOING DOWN ALOWING ROADWAY
TEMPERATURES TO FALL BELOW FREEZING...HAS CAUSED ICY SPOTS TO
FORM. HAVE BEEN HANDLING THIS WITH SPECIAL WEATHER STATEMENTS.
3. RAP DERIVED WIND GUSTS SHOW VALUES OF 35-39 KTS BETWEEN 05-15Z
ACROSS MUCH OF THE FORECAST AREA...ABOUT 5 KNOTS STRONGER THAN
WHAT MOMENTUM TRANSFER WOULD SUGGEST ON RAP FORECAST SOUNDINGS. IF
THE DERIVED VALUES WERE CORRECT...WE NEED A WIND ADVISORY.
THE IDEA OF GUSTS INCREASING SEEM REASONABLE...AS DURING THE
AFOREMENTIONED TIME PERIOD WE ARE EXPERIENCING THE TROPOPAUSE DROP
OVER 100 MB...DUE TO THE UPPER TROUGH AXIS OVER WESTERN MINNESOTA
MOVING IN. IN ADDITION...DURING THIS TIME PERIOD IS WHEN THE REAL
ARCTIC AIR SURGE TAKES PLACE WITH 925MB TEMPS DROPPING NEARLY 10C.
HOWEVER...IN THE PAST THE RAP DERIVED WIND GUSTS HAVE HAD A LITTLE
HIGH BIAS. THUS...HAVE TAKEN A COMPROMISE APPROACH AND BROUGHT
WIND GUSTS UP A COUPLE KNOTS...STILL BELOW A WIND ADVISORY.
4. LATEST HRRR MODEL RUNS OF COMPOSITE REFLECTIVITY HAS SHOWN AN
ENHANCMENT OF RETURNS DURING THE 06-12Z PERIOD ACROSS MUCH OF
WISCONSIN. RAP FORECAST SOUNDINGS DURING THE SAME TIME SHOW THAT
THE DEPTH OF THE CLOUD GROWS FROM ABOUT 4000 FT TO 8000 FT...AND
NEARLY ALL THE CLOUD IS IN THE DENDRITIC GROWTH ZONE. NOW THE LIFT
IS NOT ALL THAT IMPRESSIVE...BUT THERE IS WEAK LIFT THROUGHOUT
MUCH OF THE CLOUD DEPTH. IT APPEARS THE LIFT OCCURS WITH THE
TROPOPAUSE DROP ACCOMPANYING THE UPPER TROUGH AXIS...ALONG WITH
THE ASSOCIATED 500-300MB PV ADVECTION. GIVEN THE STEEP LOW LEVEL
LAPSE RATES IN PLACE AS WELL WITH THE COLD ADVECTION...FIGURE IT
WARRANTS RAISING PRECIPITATION CHANCES TO AT LEAST 60 ACROSS MUCH
OF WISCONSIN BETWEEN 06-12Z. STILL...THERE MAY ONLY BE A FEW
TENTHS OF HARD TO MEASURE SNOW DUE TO ALL THE WIND.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
314 PM CST MON FEB 18 2013
THE MAIN SNOW BAND WILL LIFT NORTH THROUGH THE REGION ON THURSDAY
NIGHT AS THE MAIN MID LEVEL TROUGH SWINGS NORTHWARD. THIS WILL
YIELD A BRIEF PERIOD OF MODERATE SNOW THAT WILL LIKELY BE
WEAKENING AS IT TRACKS TO THE NORTHEAST. QPF AMOUNTS APPEAR TO
RANGE FROM AROUND 0.35 INCHES IN NORTHEAST IOWA TO AROUND 0.15
INCHES IN NORTH CENTRAL WISCONSIN BY THE TIME THE SYSTEM ENDS ON
FRIDAY. WITH SNOW RATIOS EXPECTED TO BE IN THE 10/15:1 RANGE...IT
LOOKS LIKE THE HIGHEST SNOW ACCUMULATIONS SHOULD BE ACROSS
NORTHEAST IOWA AND PORTIONS OF SOUTHEAST MINNESOTA AND FAR
SOUTHWEST WISCONSIN WHERE 3-5 INCHES COULD FALL. SNOW AMOUNTS ARE
EXPECTED TO DECREASE TO THE NORTHEAST WITH A 2-4 INCH RANGE
EXPECTED INTO NORTH CENTRAL WISCONSIN.
LIGHT SNOW WILL COME TO AN END FROM SOUTH TO NORTH FRIDAY NIGHT
INTO SATURDAY WITH A BRIEF RIDGE OF HIGH PRESSURE EXPECTED TO MOVE
ACROSS THE REGION NEXT WEEKEND. ANOTHER SYSTEM IS THEN FORECAST TO
OCCUR SOMETIME BETWEEN SUNDAY AND TUESDAY WITH THE 19.12Z
GFS/ECMWF/FIM MODELS ARE SHOWING DIFFERENT TIMING IN REGARD TO
WHEN THE LOW PASSES THROUGH. THE 19.12Z GFS IS THE FASTEST WITH
HAVING THE LOW COME THROUGH ON SUNDAY WHILE THE 19.12Z ECMWF IS
THE SLOWEST WITH HAVING IT COME THROUGH ON MONDAY. THE 19.12Z FIM
SEEMS TO BE A BLEND IN BETWEEN THE TWO AND MAY BE A GOOD
COMPROMISE. THE TRACK THOUGH SEEMS TO BE SIMILAR WITH TAKING THE
CENTER OF THIS LOW OFF TO THE WEST OF THE REGION...WHICH PROBABLY
LEAVES US MORE INTO A MIXED P-TYPE.
&&
.AVIATION...TONIGHT AND TUESDAY
529 PM CST MON FEB 18 2013
MUCH OF THE TAF PERIOD WILL BE DOMINATED BY WINDY NORTHWEST
WINDS...IN THE WAKE OF DEEPENING LOW PRESSURE LIFTING FROM EASTERN
WISCONSIN INTO NORTHERN LOWER MICHIGAN. IN ADDITION...ARCTIC HIGH
PRESSURE IS FORECAST TO DROP DOWN INTO THE NORTHERN PLAINS...
MAINTAINING A TIGHT PRESSURE GRADIENT OVER THE TAF SITES THROUGH
TUESDAY. BOTH SITES SHOULD SEE SUSTAINED WINDS BETWEEN 15-25 KT
WITH GUSTS OF 30-35KT. WINDS DO LOOK TO DIMINISH SLIGHTLY TUESDAY
AFTERNOON WITH A SLIGHT WEAKENING OF THE PRESSURE GRADIENT.
THE STRONG NORTHWEST WINDS ARE DRIVING IN ARCTIC AIR INTO THE
REGION. WITH A MVFR STRATUS DECK TO REMAIN IN PLACE THROUGH
TUESDAY...AND THE STRATUS DECK INTERSECTING THE FAVORABLE DENDRITIC
GROWTH ZONE FOR SNOW PRODUCTION...EXPECT LIGHT SNOW OR FLURRIES
TO PERSIST THROUGH TUESDAY. VISIBILITIES FOR THE MOST PART SHOULD
HOLD BETWEEN MVFR AND VFR. HOWEVER...AS ARCTIC AIR SURGES IN
BETWEEN MIDNIGHT AND 6 AM TUESDAY...THE SNOW COULD INTENSIFY ON THE
LEADING EDGE TO RESULT IN IFR VISIBILITIES AS SUGGESTED BY THE
RAP/HRRR MODELS. ADDED A TEMPO GROUP TO ACCOUNT FOR THIS. TOTAL SNOW
ACCUMULATION LOOKS TO BE LESS THAN AN INCH.
FOR THOSE WORKING OUTSIDE...BE AWARE WIND CHILLS ARE GOING TO DROP
TO 10 TO 25 BELOW ZERO OVERNIGHT AND INTO TUESDAY. THE COLDEST
WIND CHILLS ARE FORECAST AROUND THE KRST TAF SITE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
314 PM CST MON FEB 18 2013
WI...NONE.
MN...WIND CHILL ADVISORY FROM 3 AM TO NOON CST TUESDAY FOR MNZ086-087-
094-095.
IA...WIND CHILL ADVISORY FROM 3 AM TO NOON CST TUESDAY FOR IAZ008-009-
018-019.
&&
$$
SHORT TERM...AJ
LONG TERM...HALBACH
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1100 PM CST SAT FEB 16 2013
.SHORT TERM...THROUGH TUESDAY NIGHT
326 PM CST SAT FEB 16 2013
MUCH OF THE TIME TODAY WAS SPENT WORKING ON MONDAY INTO TUESDAY.
IMPACTS LOOK TO BE MINIMAL AS MAIN PRECIPITATION REGION LOOKS TO
ADVECT IN JUST EAST OF THE FORECAST AREA.
CLOUDS HAVE BEEN A TOUGH FORECAST AS OF LATE...AND TONIGHT THEY
COULD HAVE A HUGE IMPACT ON LOW TEMPERATURES. CURRENT GOES
SATELLITE IMAGERY SHOWING CLOUDS EXPANDING IN WRN MN WEST OF THE
SURFACE RIDGE AXIS FROM KINL TO KALO. MAINLY CUMULUS FIELDS
ARE AFFECTING THE FORECAST AREA WITH THOSE EXPECTED TO DISSIPATE
BY LATE AFTERNOON. SURFACE OBSERVATIONS SHOWING A STATIONARY FRONT
LOCATED FROM ABOUT KFSD-KDSM WITH WARM AIR TO THE SOUTHWEST AND
CONVERGENT FLOW INTO NE IA.
GOES WATER VAPOR SHOWING THE MONDAY S/WV WELL NOW COMING ONTO THE
WEST COAST WITH THE NRN ENERGY OVER BRITISH COLUMBIA AND THE
16.19Z RAP INDICATING A TROPOPAUSE FOLD TO 400MB INTO THE OR
COAST REPRESENTING THE SRN ENERGY THAT IS FORECAST TO DIG INTO THE
CENTRAL U.S. KUIL WASHINGTON RAOB HAD A 150M/12HR HEIGHT FALL THIS
MORNING AHEAD OF THIS POTENT SHORTWAVE TROUGH.
HAVE LOWERED THE LOW TONIGHT ACROSS CENTRAL WI AS THE SURFACE
RIDGE WILL BE RIGHT OVERHEAD MOST OF THE NIGHT AND CLOUDS ARE
FORECAST TO REMAIN MINIMAL. HAVE DROPPED LOWS 5-7F THERE TONIGHT
FROM PREVIOUS FORECAST. CLOUDS ARE TOUGH THOUGH AND AM THINKING
TWO AREAS COULD DEVELOP STRATUS...CURRENT HEAVY CUMULUS AREA OVER
NRN WI AND CONVERGENT BOUNDARY ACROSS IA. THE NRN WI AREA COULD
EXPAND OVER NRN FORECAST AREA LATE AND CLOUDS WILL ALSO SPREAD IN
FROM THE SW. THUS...LOW CONFIDENCE IN FORECAST CLOUDS AND LOWS
TONIGHT...BUT FORECASTING THE CENTRAL FORECAST AREA TO REMAIN
MOSTLY CLEAR.
WARM ADVECTION TO KICK IN SUNDAY AND PEAK SUNDAY NIGHT WITH
WARMING OCCURRING INTO MONDAY WEATHER SYSTEM. 16.12Z MODEL
CONSENSUS IS TO STILL DEVELOP THE NRN CYCLONE THE MOST...NORTH OF
THE GREAT LAKES...WITH THE SRN ENERGY CAUSING WEAK CYCLOGENESIS
ALONG THE FRONTAL BOUNDARY AS IT PASSES TO THE SE OF THE FORECAST
AREA. SOME SPREAD STILL REMAINS IN THE GUIDANCE. THE 16.12Z NAM
REMAINS CONSISTENT WITH IT/S PREVIOUS RUNS OF THE DRY OUTLIER. THE
16.12Z CANADIAN GLOBAL GEM STILL INSISTS ON A WET 0.30 INCHES
AREA-WIDE WITH THIS SYSTEM /AND HIGHS IN THE 40S/. STILL PREFER THE
CONSISTENT ECMWF/GFS RUNS ON THE OUTCOME FOR THIS SYSTEM. IT
APPEARS THE MAIN MOISTURE AXIS WILL ONLY GRAZE THE ERN FORECAST
AREA FROM CENTRAL WI TO SWRN WI...A STEP EAST FROM PREVIOUS MODEL
RUNS. THIS SAME AREA WILL SEE THE DEEPEST SURFACE-BASED SATURATION
COME IN MONDAY MORNING /KOVS 0-2 KM/...WITH THE LAYER MORE SHALLOW
FURTHER TO THE NW /KEAU 1KM/. NW OF THE SURFACE WAVE...WOULD THINK
A BIT OF ENHANCEMENT IN THE DEFORMATION WILL OCCUR AND HAVE KEPT
HIGHEST PRECIPITATION CHANCES IN THAT SWRN-CENTRAL WI
AREA...TAPERING LOWER TO THE NORTHWEST.
IT APPEARS DEEP SATURATION TO COLDER THAN -10C TO GET ICE GROWTH WILL
BE TROUBLESOME/SPOTTY OR JUST PLAIN HARD TO FORECAST WITH THIS
SYSTEM. THE Q-G FORCING IS MODERATE ALOFT AND WEAKER IN THE LOW
LEVELS PROVIDING OVERALL A WEAK BUT PRESENT LIFT SIGNAL. BUT
REVIEWING MODEL SOUNDINGS FROM THE 16.09Z SREF AND 16.12Z NAM/GFS
THERE IS CONSISTENT STRUGGLES WITH SATURATION NOTED...AND THUS
HAVE GONE WITH A MAJORITY OF LIQUID IN THE FORECAST UNTIL THE COLD
FRONT MOVES IN LATER MONDAY WITH VERY STRONG COLD ADVECTION TO DRIVE
THE ICE PROCESS AND SNOW CONVERSION. THIS SATURATION STRUGGLE AWAY
FROM THE SURFACE WAVE IS ALSO WHY PRECIPITATION CHANCES ARENT
HIGHER FOR THIS FORECAST.
MONDAY MORNING WILL SEE THE MOISTURE INCREASE AND SURFACE TEMPERATURES
WARMING TO NEAR OR ABOVE FREEZING IN THE AFTERNOON. THIS WILL
CAUSE A FZDZ POSSIBILITY MAINLY IN THE MORNING IF THE LAYER CAN
PRECIPITATE...PROBABLY VERY LIGHT AMOUNTS AROUND 0.01-0.02 INCHES
TO PROVIDE A LIGHT GLAZE AFTER COMMUTE TIME. MANY AREAS SOUTH OF
I-90 WILL WARM TO ABOVE FREEZING BY MID-DAY...ESPECIALLY CLOSE TO
THE MOIST AXIS SO IMPACTS WOULD BE MINIMAL THERE...OR AT LEAST
SHORT LIVED. HAVE KEPT FZDZ STILL POSSIBLE FOR POINTS WITH AIR
TEMPERATURES OF 35F OR COLDER AS ROADS MAY STILL BE SLOWER TO
RECOVER TO ABOVE FREEZING.
THE NORTHERN AND WESTERN AREAS COULD SEE FZDZ PERIODICALLY MONDAY
THROUGH THE DAY...POSSIBLE MIXING WITH SNOW AS SATURATION OCCURS
IN A PATCHY WAY. THE COLD FRONT WILL SWEEP IN WITH VERY STRONG
COLD ADVECTION CONVERTING ALL LIGHT LIQUID PRECIPITATION TO SNOW.
WITH THE COLD ADVECTION STRONG...LAPSE RATES IN THE LOWEST 1 KM
ARE QUITE STEEP AND WILL PROMOTE WIND GUSTS IN THE 25 TO 35 MPH
RANGE LATE MONDAY AND OVERNIGHT. HAVE INCREASED THE WINDS WITH
THIS FORECAST BASED ON 16.12Z NAM/GFS BLEND.
OVERALL...COMFORT REMAINS LOW ON THIS SYSTEM /I HAVE MORE
CONFIDENCE IN THE THU-FRI SNOW/ BUT MY FEELING IS THAT THE IMPACTS
WILL BE MINOR. DO NOT FEEL A NEED FOR A HEADLINE ON THIS SYSTEM AS
THE LIQUID AMOUNTS LOOK TO BE PRETTY LIGHT. IN THE DEFORMATION
AREA TEMPERATURES WOULD BE WARMEST AND MAINLY RAIN WOULD FALL. BUT
THERE ARE SOME HINTS THAT UP TO A TENTH OF PRECIPITATION COULD
FALL MONDAY AWAY FROM THE MOISTURE AXIS /KEAU SREF MEAN GIVES 0.07
OF FZDZ/ SO IT IS STILL A SYSTEM TO WATCH.
.LONG TERM...WEDNESDAY THROUGH SATURDAY
326 PM CST SAT FEB 16 2013
THE FOCUS REMAINS ON THE INCREASINGLY ADVERTISED LATE WEEK SYSTEM
AND THE DEGREE OF IMPACT IT WILL HAVE ON THE UPPER MIDWEST. LEADING
UP TO THAT FEATURE...WEDNESDAY LOOKS TO BE A TRANSITION DAY WITH
MORNING COLD ADVECTION AS A SURFACE HIGH AND UPPER LEVEL RIDGE AXIS
REMAINS TO THE WEST OF THE FORECAST AREA. A COLD DAY ON TAP AS
MORNING LOWS IN THE SINGLE DIGITS BELOW/ABOVE ZERO LOOK TO RISE INTO
ONLY THE TEENS. THE RIDGE IS THEN EXPECTED TO BUILD ACROSS BY
WEDNESDAY NIGHT...LEADING TO RETURN SOUTHERLY FLOW. A WESTERN CONUS
TROUGH THEN DIGS AND MOVES EAST...EJECTING THE MAIN SHORTWAVE
TROUGH OUT OF THE COLORADO ROCKIES BY 12Z THURSDAY. SURFACE LOW
DEEPENS RAPIDLY ACROSS THE CENTRAL PLAINS THURSDAY...LIFTING
TOWARD THE AREA.
THE 16.12Z GFS ENSEMBLE REMAINS CLOSELY PACKED WITH A LOW TRACK
ALONG A KANSAS CITY TO NORTHERN ILLINOIS LINE THURSDAY NIGHT INTO
FRIDAY AFTERNOON. THE 16.12Z ECMWF TOOK A STEP NORTHWEST WITH ITS
SURFACE LOW TRACK AND THE 16.12Z GEM AND FIM REMAIN THE SOUTHERLY
OUTLIERS. THE GFS SEEMS TO BE A GOOD COMPROMISE. EARLIER TIMING
ISSUES APPEAR TO BE RESOLVED FOR NOW. YESTERDAY/S CONCERNS ABOUT THE
FILLING UPPER LEVEL TROUGH / SURFACE LOW AND ITS IMPACT WERE MUTED
SLIGHTLY SINCE THE 16.12Z GFS...ECMWF AND FIM CAME IN A BIT
STRONGER. HOWEVER...500 MB HEIGHT STANDARDIZED ANOMALIES STILL RISE
FROM -3.5 ACROSS THE CENTRAL PLAINS...TO AROUND -0.5 BY 12Z FRIDAY
WHICH SUGGESTS A WEAKENING TREND AND THE SYSTEM NOT NEARLY AS WOUND
UP AS IT MAY BE IN THE CENTRAL PLAINS.
PRECIPITATION WOULD OVERSPREAD THE AREA DURING THE AFTERNOON
THURSDAY...WITH THE MAIN WARM ADVECTIVE WING SWINGING THROUGH
THURSDAY NIGHT AND OVERNIGHT FRIDAY. THIS WOULD BE WHEN THE HIGHEST
SNOW RATES OCCUR. AS THE SURFACE LOW THEN MOVES NEARBY...WRAP AROUND
/ DEFORMATION BANDING SNOW WOULD LINGER THROUGHOUT FRIDAY. SOUNDINGS
STILL POINT TO AN ALL SNOW EVENT WITH THE WARMEST AIR REMAINING
SOUTH OF THE AREA.
THE MODEL CONSISTENCY AND RUN-TO-RUN SIMILARITIES REMAIN VERY ABOVE
AVERAGE AND REMARKABLE FOR IT STILL BEING 6 DAYS OUT. GIVEN THE
FEATURE IS CURRENTLY OVER THE DATA SPARSE NORTHERN PACIFIC...THERE
CERTAINLY WILL BE FINE-TUNE DETAILS TO ESTABLISH. PRECIPITATION
AMOUNTS TOOK A STEP UP IN THE LATEST ROUND OF GUIDANCE THOUGH STILL
REMAIN BETWEEN 0.7 TO 1.0 INCH. CONFIDENCE CONTINUES TO GROW IN A
WARNING LEVEL EVENT WITH WIDESPREAD 6 TO 10 INCH AMOUNTS IF THE
CURRENT AND PAST SOLUTIONS INDEED VERIFY. THE BIG PICTURE IS THAT
THOSE WITH INTERESTS AND TRAVEL CONCERNS LATE NEXT WEEK SHOULD
CONTINUE TO MONITOR AND FOR NOW...HAVE CONTINUED TO PUSH HIGHER
PRECIPITATION CHANCES THURSDAY NIGHT...AND TRENDED FRIDAY HIGHER AS
WELL SINCE IF THE SYSTEM DOES SLOW DOWN / FILL IN THEN THERE WOULD
CERTAINLY BE LINGERING DEFORMATION BANDING SNOW ACROSS MUCH OF THE
AREA. THE PROLONGED DURATION / THURSDAY NIGHT THROUGH LATE FRIDAY
NIGHT / COULD PRESENT SOME CHALLENGES FOR TRAVELERS AND ROAD CREWS
AS WELL.
&&
.AVIATION...THROUGH 06Z MONDAY
1100 PM CST SAT FEB 16 2013
BAND OF VFR STRATUS APPROACHING INTERSTATE 35 IS A LITTLE LESS
EXPANSIVE THAN PREVIOUSLY THOUGHT TO THIS POINT...BUT PERSISTENT
WARM AIR AND SOME MOISTURE SHOULD EVENTUALLY RESULT IN EITHER A
SCATTERED OR BROKEN DECK CROSSING THE TAF SITES TODAY. BASES LOOK
TO BE AT OR ABOVE 6000 FT. FARTHER TO THE WEST...AN AREA OF MVFR
STRATUS EXISTS OVER EASTERN SOUTH DAKOTA. AS LOW LEVEL WINDS TURN
MORE SOUTH TO SOUTHWEST TODAY...THIS LOW STRATUS DECK LOOKS TO
LIFT TO THE NORTHEAST...THUS STAYING AWAY FROM THE TAF SITES.
OTHERWISE...THE ONLY CLOUDS TO CONTEND WITH WILL BE SOME
CIRROSTRATUS DROPPING SOUTH OUT OF NORTH DAKOTA.
WINDS ARE AN ISSUE FOR THE FORECAST. THE PRESSURE GRADIENT IS
FORECAST TO TIGHTEN OVER THE TAF SITES TODAY INTO THIS
EVENING...IN RESPONSE TO LOW PRESSURE APPROACHING THE AREA FROM
THE PLAINS. SOUTHEAST WINDS LOOK TO KICK UP TO 10-20 KT WITH GUSTS
OF 15-25KT. THE STRONGEST WINDS AND BULK OF THE GUSTS WILL OCCUR
AT KRST WHERE THE GRADIENT IS TIGHTEST AND THE AIR CAN STAY MORE
MIXED. AT KLSE...AFTER A BRIEF PERIOD OF GUSTS IN THE AFTERNOON...
COOLING IN THE EVENING IS EXPECTED TO ALLOW FOR LOW LEVEL WIND
SHEAR TO DEVELOP. SOUTH WINDS OF 40-50 KT ARE SUGGESTED BETWEEN
1500-2000 FT FOR MUCH OF TONIGHT AT BOTH TAF SITES...BUT THE
STRONGER SURFACE WINDS AT KRST PRECLUDES THE NEED FOR LOW LEVEL
WIND SHEAR THERE.
LOOKING AHEAD...LOW CLOUDS ALONG WITH A LIGHT WINTRY MIX COULD
IMPACT BOTH TAF SITES ON MONDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
151 PM CST SAT FEB 16 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...TAYLOR
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1033 PM CST SAT FEB 16 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SYNOPSIS...
ISSUED AT 223 PM CST SAT FEB 16 2013
MODERATING TEMPS WITH SOME LIGHT TO MODERATE PRECIPITATION MONDAY
NIGHT AND TUESDAY. STILL PLENTY OF QUESTIONS ABOUT THE NEXT SYSTEM
EXPECTED TO ARRIVE LATE IN THE WEEK.
UPR FLOW ACRS NOAM WL START OUT WITH A BROAD RIDGE OVER THE ERN
PAC/WRN NOAM...ALBEIT WITH STG SHRTWV RIGHT IN THE MIDDLE OF THE
RIDGE POSN. A DEEP TROF WAS OVER ERN NOAM...WITH RIDGING OVER THE
WRN ATL. THE SHRTWV NOW IN THE WRN RIDGE POSN AND ITS SUCCESSOR WL
BOTH DIG PROGRESSIVELY FARTHER W...EVENTUALLY PULLING THE MEAN
TROF POSN BACK INTO THE WESTERN CONUS BY MID-WK. MEANWHILE...THE
DOWNSTREAM PATTERN OVER THE ATL WL BREAK DOWN INTO A COMPLEX
BLOCKING REGIME. THE BLOCKING WL EVOLVE WWD WITH TIME...
RESULTING IN A SPLIT FLOW ACRS MUCH OF THE CONUS BY NEXT WEEKEND.
THE TWO MAJOR SHRTWVS WORKING ACRS THE CONUS DURING THE PERIOD WL
BOTH SUPPORT STG CYCLONES. THE CHANGING UPR PATTERN AND PASSAGE OF
THE CYCLONES WL TAKE TEMPS ON A ROLLERCOASTER RIDE DURING THE
PERIOD. THEY/LL START OUT COLD...QUICKLY WARM EARLY IN THE WEEK...
DROP BACK TO BLO NORMAL MID-WEEK...THEN SETTLE BACK CLOSER TO
NORMAL AS THE FLOW SETTLES INTO SPLIT REGIME. GIVEN THE 2 SIG
SYSTEMS LIKELY TO IMPACT THE AREA...PCPN AMNTS WL PROBABLY END UP
AOA NORMAL.
&&
.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 223 PM CST SAT FEB 16 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH
PRESSURE RIDGE STRETCHING FROM TEXAS TO ONTARIO THIS AFTERNOON.
STEEPENING LOW LEVEL LAPSE RATES AND FLOW OFF SUPERIOR CONTRIBUTED
TO A WIDESPREAD DIURNAL CU FIELD...WHICH SPREAD SOUTH ACROSS MUCH
OF THE CWA BY EARLY THIS AFTERNOON. LAKE EFFECT SNOW SHOWERS
REMAINED CONFINED TO NORTHERN VILAS COUNTY AND POINTS NORTH AND
VSBYS IN THIS AREA SUGGEST ONLY MINOR ACCUMS AT BEST. PRETTY QUIET
UPSTREAM AS WELL. FGEN INDUCED BAND OF CLOUDS AND LIGHT SNOW OVER
THE PLAINS IS SLIDING SE WHILE SKY CONDITIONS ARE CLEARING OVER
MINNESOTA. CLOUD TRENDS AND TEMPS ARE THE MAIN FORECAST CONCERNS
IN THE SHORT TERM.
TONIGHT...SURFACE HIGH PRESSURE TO MOVE ACROSS THE REGION AND
THIS SHOULD RESULT IN LOW LEVEL FLOW BECOMING LIGHT THIS EVENING.
ANTICIPATING STRATO-CU TO RAPIDLY DIMINISH WITH LOSS OF DAYTIME
HEATING EARLY THIS EVENING...EXCEPT OVER NORTH-CENTRAL WISCONSIN
WHERE IT SHOULD TAKE A FEW HOURS LONGER. AS A RESULT...EXPECT SKY
CONDITIONS TO BECOME CLEAR TO MOSTLY CLEAR ACROSS THE REGION BY
LATE THIS EVENING. STRATUS UPSTREAM THIS MORNING BENEATH THE RIDGE
AXIS SEEMED ALIGNED WITH A LOW LEVEL THERMAL GRADIENT. THIS
GRADIENT DOES NOT MOVE MUCH TONIGHT...SO AM NOT EXPECTING CLOUDS
TO REFORM BENEATH THE SURFACE HIGH. TEMPS LAST NIGHT FELL INTO THE
TEENS BELOW ZERO OVER N-C WISCONSIN. SHOULD HAVE LIGHTER WINDS IN
THE BOUNDARY LAYER AND THE PWAT MINIMUM OVERHEAD...SO HAVE DROPPED
TEMPS FROM THE PREVIOUS FORECAST.
SUNDAY...HIGH PRESSURE MOVES EAST OF THE REGION AND RETURN FLOW
WILL PUSH A WARM FRONT INTO THE NORTHERN MISSISSIPPI VALLEY BY THE
AFTERNOON. THOUGH MID AND HIGH CLOUDS WILL BE INCREASING THROUGH
THE DAY...DEEPER MOISTURE WILL STAY WELL OFF TO THE NORTHWEST OVER
NORTHERN MINNESOTA AND SOUTH-CENTRAL CANADA. HIGHS WILL BE
CONSIDERABLY WARMER THAN TODAYS READINGS...AND MOSTLY RANGE FROM
THE LOWER TO MIDDLE 20S.
.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 223 PM CST SAT FEB 16 2013
WAA ON THE BACK SIDE OF DEPARTING RIDGE WL KICK INTO HIGH GEAR
SUN NGT. THE STRONGEST ISENT LIFT AND BEST CHC AT SATURATION WL BE
ACRS THE N. WENT WITH CHC POPS THERE...AND KEPT THE S DRY. EXPECT
EVENING MINS THEN RISING TEMPS.
COMPLEX STORM SYSTEM DRIVEN BY PHASING SHRTWVS WL BE ORGANIZING
AS IT CROSSES THE AREA MON...THEN DEEPEN JUST OFF TO OUR E MON NGT
INTO TUE. RAISED POPS AS FORCING LOOKS FAIRLY STG. BUT MOISTURE WL
BE LIMITED...ESP INITIALLY. THAT WL PROBABLY RESULT IN ANOTHER
EVENT WITH MESSY MIX OF SN/DZ/FZDZ DEPENDING ON WHETHER SUFFICIENT
MID-LVL MOISTURE IS PRESENT AT ANY TIME TO SEED THE LOWER CLDS FM
ABV. MODEL FCST SOUNDINGS SUGGEST LOWER-LEVELS OVER E-C WI COULD
BRIEFLY BE WARM ENOUGH FOR JUST RAIN MON AFTN EVEN IF MOISTURE IS
DEEP AT THAT TIME. WENT WITH MAINLY SN/FZDZ ACRS THE NW AND RA/SN
IN THE SE ON MON. E-C WI COULD CERTAINLY SEE DZ RATHER THAN
RAIN... BUT WANTED TO AVOID HAVING TOO MANY PCPN TYPES IN THE
FCST.
PCPN SHOULD CHG TO SNOW MON NGT...WITH SHSN ON THE BACK SIDE OF
THE SYSTEM CONTG INTO TUE. UPPED POPS AS UPR TROF WL BE SHARPENING
RIGHT ACRS THE AREA DURING THAT TIME. THINKING RIGHT NOW IS THAT
THIS WL BE A 1-3 INCH EVENT...WITH THE HIGHER TOTALS IN THE NE.
LAKE-EFFECT OFF LAKE SUPERIOR COULD BOOST TOTALS EVEN FURTHER OVER
THE SNOWBELT...THOUGH THAT DEPENDS ON EXACT TRAJECTORIES SO WON/T
GET TOO SPECIFIC WITH THAT YET.
A BREAK FM THE SIG PCPN THEN EXPECTED WED INTO THU AS UPR RIDGE
SHARPENS ACRS THE AREA. STG...COLD...VERY DRY LOW-LEVEL
ANTICYCLONE WL BE RIDGING SWD INTO THE RGN FM THE HUDSON BAY AREA.
LOW-LEVEL WINDS WL VEER ARND TO THE E...AND ALTHOUGH THE UPSTREAM
AIR WL BE VERY DRY AND INVERSION HEIGHTS WL BE LOW...WL PROBABLY
GET SOME LAKE FLURRIES INTO E-C WI.
STILL A LOT OF QUESTIONS ABOUT THE SYSTEM HEADING INTO THE AREA
DURING THE LATTER PART OF THE WEEK. DON/T LIKE THAT THE SYSTEM WL
BE DRIVING INTO A DOWNSTREAM BLOCK AND HAVE VERY DRY AIR FEEDING
INTO IT FM THE E AT LOW-LEVELS. THAT/S A CLASSIC LATE WINTER/EARLY
SPRING FCST PROBLEM HERE...AND IT TYPICALLY RESULTS IN A CONSTANT
DELAYING OF THE ONSET OF PCPN...AND OFTEN A REDUCTION IN PCPN
TOTALS. ON THE OTHER HAND...IF SYSTEM CAN GET PCPN INTO THE
AREA...DOWNSTREAM BLOCKING WL CAUSE IT TO SLOW TO A CRAWL...AND
RESULT IN A LONG-DURATION EVENT.
FEELING RIGHT NOW IS THAT THIS IS A SYSTEM THAT WL HAVE IT/S
GREATEST IMPACT OUT IN THE PLAINS. MAX SNOWS WL PROBABLY END UP IN
THE SW PART OF THE FCST AREA...AND THEY WILL PROBABLY BE
CONSIDERABLY LESS THAN WHAT FALLS TO OUR SW. AT THIS POINT...WAS
CONTENT WITH INITIALIZATION GRIDS THAT NEVER WENT BEYOND LIKELY
POPS. CERTAINLY PLENTY OF TIME FOR LATER SHIFTS TO ADJUST FCST.
WL CONT TO MENTION SYSTEM IN THE HWO...BUT DON/T PLAN ON PLAYING
THIS UP AS A BIG STORM.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
VFR CONDITIONS EXPECTED THROUGH THE PERIOD...WITH AN INCREASE OF
MID LEVEL CLOUDS AS WARMER AIR WORKS NORTH INTO THE REGION ON
SUNDAY AND SUN EVENING. STRONG LOW LEVEL WINDS FROM THE SOUTHWEST WILL
LEAD TO LOW LEVEL WINDSHEAR DURING THE EVENING WEST...EAST AROUND MIDNIGHT.
TE
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
338 AM EST TUE FEB 19 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK FROM THE GREAT LAKES REGION TODAY, THEN
ACROSS SOUTHEASTERN CANADA TO NORTHERN NEW ENGLAND TONIGHT AND
WEDNESDAY. AN ASSOCIATED COLD FRONT WILL SLIDE ACROSS OUR AREA
THIS EVENING. HIGH PRESSURE FROM CENTRAL CANADA WILL THEN BUILD
SOUTH AND EASTWARD THURSDAY. THIS HIGH WILL BE SHIFTING EAST LATE
THURSDAY INTO FRIDAY, AS ANOTHER LOW PRESSURE SYSTEM MOVES INTO THE
GREAT LAKES AND OHIO VALLEY FRIDAY NIGHT INTO SATURDAY. LOW PRESSURE
FARTHER SOUTH ON THE COLD FRONT THEN EXITS THE MID ATLANTIC COAST
SATURDAY NIGHT INTO SUNDAY. HIGH PRESSURE THEN ARRIVES LATE SUNDAY
INTO MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE GFS INITIALIZATION LOOKED SLIGHTLY BETTER THAN THE WRF-NMMB AND
THE FORECAST PACKAGE WAS LEANED ABOUT THREE QUARTERS TOWARD ITS
TIMING. WE DID OPT FOR THE WRF-NMMB SFC THERMAL FIELDS OVER THE GFS
IN THE POCONOS.
THE OVERALL FORCING STILL LOOKS SPLIT. THE FCST ISENTROPIC LIFT IS
NOT ROBUST, THE MID LEVEL QVEC CONVERGENCE AND FGEN FORCING WEAKEN
AS IT MOVES ACROSS THE APPALACHIANS. THE LOW LEVEL THETA E RIDGE IS
NOT ANYTHING TO WRITE HOME FOR (PLENTY OF LOW SFC DEW POINTS INTO
GEORGIA). THE BEST "CONVECTIVE" CONTRIBUTION GOES NORTHWEST OF CWA.
WHAT IT STILL DOES HAVE GOING FOR IT IS THE EXIT REGION OF THE 250MB
JET. WE SAW WHAT THAT DID FOR THE SYSTEM LAST FRIDAY NIGHT AND WE
ARE COUNTING ON IT TO SAVE THE QPF DAY.
SENSIBLE WEATHER, WE START BRINGING IN THE POPS AT 14Z, CLOSER TO
THE GFS TIMING. THERE IS PLENTY OF DRY AIR FOR THIS MOISTURE TO
OVERCOME, SO WE BELIEVE IT WILL TAKE A COUPLE OF HOURS FOR PCPN TO
GET GOING (EARLY TO MID AFTERNOON). THIS ALSO COINCIDES BETTER WITH
THE JET. THE THETA E RIDGE GETS OFFSHORE PRETTY FAST AND THE FCST
MID LVL WAA IS WAY EAST BY 00Z, SO POPS WERE DROPPED LATE IN THE
AFTERNOON IN THE WEST.
FOR PTYPE, THE DRY AIR MASS IN PLACE WILL MAKE IT EASY TO EVAPORATE
COOL TO SNOW. THE QUESTION IS HOW DEEP WILL THE THERMAL SOUNDING
HAVE TO BE COOLED FOR SNOW. THE LATEST ACAR SOUNDING FROM PHL
ALREADY HAS THE FREEZING LEVEL ABOVE 6K. SO THE "MENTION" OF SNOW
WAS LIMITED TO THE PHL FAR NWRN SUBURBS, RARITAN BASIN IN NJ AND
POINTS NW. THE LATER ARRIVAL TIME AND LIKELY LIGHT INTENSITY
START HAS PRETTY MUCH REMOVED THE RISK FOR FREEZING RAIN.
THE ONLY LOCALE THAT SHOULD HANG ON TO SNOW ARE THE POCONOS WHERE
THE WRF/HI RES ARW/ AND HRRR ALL DROP SFC TEMPS TO FREEZING AND
LEVEL THEM THERE. LATE IN THE DAY SOME SOUNDINGS SUGGEST WE LOSE THE
ICE AND WITH LESSER INTENSITY AND A CONTINUING SOUTH WIND, THE SNOW
COULD MIX OR CHANGE TO RAIN EVEN THERE. AS MENTIONED ABOVE THE MID
LEVEL FGEN FORCING WEAKENS AND THE BEST FGEN FRCG THAT MAKES IT
ACROSS THE MOUNTAINS REMAINS TOWARD THE 500MB LEVEL, COMES AS NO
SURPRISE THAT THE BEST OMEGA IS FCST TO ABOVE THE SNOW GROWTH AREA.
THIS COMBINED WITH MODEL QPFS OF AROUND A QUARTER OF AN INCH SUGGEST
AN INCH OR TWO OF SNOW AS THE MOST LIKELY OUTCOME FOR THE HIGHER
TERRAIN IN THE POCONOS, SO NO ADVISORY WILL BE ISSUED AT THIS TIME.
OUR BIGGEST UNCERTAINTY REMAINS WITH THE WIND AND TO A CERTAIN
DEGREE ITS TIED TO THE TEMPERATURES. THE FORECAST SOUNDINGS REMAIN
VERY BULLISH ON DEEP MIXING AND ALBEIT TAKING THE HIGHER LEVEL OF
THE TWO BUFKIT MOMENTUM TRANSPORT WINDS GIVE US ADVISORY LEVEL WIND
GUSTS. OF LATE THE SFC GUSTS HAVE BEEN BETTER REPRESENTED BY THE
LOWER TRANSPORT GUST WHICH SUGGEST INTO THE 30S FOR GUSTS. THERE MAY
BE A WINDOW OF OPPORTUNITY FOR MORE ROBUST GUSTS THAN WE ARE
FORECASTING BEFORE THE SHOWERS ARRIVE AND MAKE THE SOUNDING MORE
ISOTHERMAL. THIS WILL DEPEND ON TEMPERATURES JUMPING THIS MORNING
BEFORE THE SHOWERS ARRIVE AND GETTING HIGHER THAN WE ARE CURRENTLY
ANTICIPATING. WHETHER ITS THE CHILLY BAYS OR OCEAN OR SKY COVER, MOS
GUIDANCE REMAINS PRETTY CONSERVATIVE WITH MAX TEMPS (AND WITH THE
WINDS TOO). WE STAYED CLOSE TO THEM NORTHWEST OF I95, BUT WERE MORE
BULLISH THAN BOTH SOUTHEAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
THE COLD FRONT SHOULD CLEAR OUR CWA EARLY THIS EVENING AND ANOTHER
COLD AIR MASS WILL START WORKING ITS WAY INTO OUR CWA. ANY POPS AWAY
FROM THE HIGHER TERRAIN WERE IN JUST EARLY IN THE EVENING. THERE
ARE MODEL DIFFERENCES AS TO HOW QUICKLY THE LAKE EFFECT MACHINE GETS
GOING. EVEN WITHOUT IT, THERE ARE ENOUGH SHORT WAVES MOVING THROUGH
TO LIKELY TRIGGER SOME SNOW SHOWERS NORTHWEST AND WE KEPT POPS GOING.
LIKE TODAY, WE THINK STAT GUIDANCE MAY BE A BIT TOO WEAK WITH THE
WINDS. GIVEN THE STRONG CAA, WE WENT HIGHER. IN TANDEM WE WERE ALSO
LOWER THAN STAT GUIDANCE WITH THE MIN TEMPS.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE SYNOPTIC SETUP IS AN ACTIVE ONE AND IS INITIALLY COMPRISED OF A
STRONG UPPER-LEVEL TROUGH IN THE NORTHEAST WITH ANOTHER ONE DIGGING
ACROSS THE INTERMOUNTAIN WEST. THE FIRST ONE EXITS THROUGH THURSDAY,
THEN THE BROADENING OF THE TROUGH IN THE WEST HAS SOME ENERGY THAT
EJECTS INTO THE PLAINS AND OHIO VALLEY. THIS SYSTEM MAY BECOME
STRETCHED OUT AS IT WEAKENS DUE TO THE MAIN TROUGH DAMPENING OUT
WHILE IT RELOADS ONCE AGAIN IN THE WEST. THE SOUTHERN JET LOOKS TO
REMAIN ACTIVE, THEREFORE ENERGY TRAVERSING THIS CORRIDOR WILL TEND
TO SLIDE OFF THE MID ATLANTIC COAST. WE MAY SEE THE SYSTEM ORGANIZE
MORE AS IT EXITS OFF THE MID ATLANTIC COAST DURING THE WEEKEND AS
SHORT WAVE ENERGY SHARPENS A BIT AND INCREASING BAROCLINIC EFFECTS
OCCUR. YET ANOTHER LARGE STORM LOOKS TO EJECT INTO THE PLAINS EARLY
NEXT WEEK WITH ITS COLD FRONT /OR EVEN OCCLUDED FRONT/ APPROACHING
FROM THE WEST MONDAY NIGHT. WE USED A MODEL BLEND FOR WEDNESDAY INTO
FRIDAY, THEN USED HPC GUIDANCE AND CONTINUITY THEREAFTER.
FOR WEDNESDAY AND THURSDAY...AN UPPER-LEVEL TROUGH IS FORECAST TO
DOMINATE THE NORTHEAST AS LOW PRESSURE TRACKS ACROSS SOUTHEASTERN
CANADA AND NEW ENGLAND, THEN EVENTUALLY TO THE CANADIAN MARITIMES.
THERE IS DECENT 850 MB CAA FORECAST WEDNESDAY BEFORE IT BACKS OFF
WEDNESDAY NIGHT AND THURSDAY. THE COMBINATION OF THE CAA AND A TIGHT
PRESSURE GRADIENT LEADS TO BLUSTERY CONDITIONS. THIS LOOKS SIMILAR
TO THIS PAST SUNDAY, HOWEVER THE MID LEVEL COLD CORE IS FORECAST TO
NOT BE QUITE AS COLD COMPARED TO SUNDAY. DESPITE THIS, VERTICAL
MIXING WILL DEEPEN WEDNESDAY AND THE FORECAST SOUNDINGS SHOW GUSTS
TO NEAR 35 KNOTS ARE CERTAINLY POSSIBLE. THE FLOW AT 925 MB IS
FORECAST TO BE MAINLY IN THE 30-35 KNOT RANGE WITH SOME HIGHER WINDS
AT 850 MB. IF WE ARE ABLE TO MIX EVEN DEEPER, THEN SOME NEAR ADVISORY
LEVEL GUSTS /40 KNOTS/ WILL BE POSSIBLE. WE WOULD LIKE TO SEE
WINDS CLOSER TO 50 KNOTS AT 850 MB FOR ADVISORY LEVEL WINDS,
THEREFORE WE WILL CONTINUE WITH GUSTS UNDER CRITERIA HOWEVER IT
WILL STILL BE A BLUSTERY/WINDY DAY.
THE GUSTY WINDS SHOULD CONTINUE WEDNESDAY NIGHT DESPITE WHEN WE
TYPICALLY SEE THEM DECOUPLE. THE PRESENT OF ENOUGH OF A MIXED LAYER
WILL KEEP AT LEAST SOME WIND GOING THROUGH THE NIGHT. THE AIRMASS
STARTS TO MODIFY DURING THURSDAY HOWEVER THE WESTERN EDGE OF THE MID
LEVEL COLD CORE IS NEARBY AND THIS WILL STILL COMBINE WITH A
LINGERING TIGHTENED PRESSURE GRADIENT TO RESULT IN BRISK CONDITIONS.
THESE WINDS WILL EASE UP AND BECOME NORTHERLY LATER THURSDAY AS HIGH
PRESSURE BUILDS DOWN FROM NEAR THE GREAT LAKES.
THE CAA ALONG WITH A NORTHWEST FLOW WILL PRODUCE LAKE EFFECT SNOW
DOWNWIND OF LAKES ERIE AND ONTARIO. THIS FLOW LOOKS CONDUCIVE TO
CARRY SOME STREAMERS INTO NORTHEASTERN PENNSYLVANIA, THEREFORE WE
WILL CARRY HIGHER CHC POPS INTO THE POCONOS FOR AT LEAST SCATTERED
SNOW SHOWERS. THIS SHOULD EASE UP ESPECIALLY THURSDAY AS THE AIRMASS
STARTS TO MODIFY AND THE FLOW MAY TURN MORE NORTHERLY.
FOR FRIDAY AND SATURDAY...THERE IS GENERALLY LOWER CONFIDENCE DURING
THIS TIME FRAME AS OUR SENSIBLE WEATHER IS FROM ENERGY THAT BECOMES
STRETCHED OUT FROM THE MIDWEST TO THE OHIO VALLEY AND SOUTHWARD.
HIGH PRESSURE CENTERED ACROSS SOUTHEASTERN CANADA LOOKS TO BE WEDGED
DOWN INTO THE MID ATLANTIC FOR A TIME FRIDAY. THIS MAY RESULT IN
SOME COLDER LOW-LEVEL AIR REMAINING WHILE WARMING TAKES PLACE ALOFT.
THE PRECIPITATION SHIELD WITH THIS INCOMING SYSTEM MAY END UP
SPLITTING, WITH THE MORE ORGANIZED AREA TO OUR SOUTH. WHILE WE HAVE
WAA, THE ISENTROPIC UPGLIDE AND ASSOCIATED LARGE SCALE ASCENT LOOKS
WEAKER OVER OUR AREA. THIS COULD JUST RESULT IN SOME LIGHT
PRECIPITATION. THERE LOOKS TO BE ENOUGH DRY AIR IN PLACE AHEAD OF
THIS FEATURE, WHERE THE PRECIPITATION DOES NOT START UNTIL LATER IN
THE DAY FRIDAY.
THERE DOES LOOK TO BE ENOUGH ENERGY IN THE SOUTHWEST FLOW ALOFT TO
ORGANIZE A SURFACE LOW, WHICH THEN TRACKS TO OUR SOUTH SATURDAY.
THIS COULD KEEP MORE OF AN EASTERLY WIND ACROSS OUR AREA ALONG WITH
COOLER TEMPERATURES. AT THIS JUNCTURE, PRECIPITATION LOOKS TO BE ON
THE LIGHT TO MODERATE SIDE UNLESS THE SYSTEM TRACKING OFF THE MID
ATLANTIC COAST CAN STRENGTHEN SOME MORE WHICH RESULTS IN STRONGER
LIFT SPREADING NORTHWARD. THE ECMWF IS INDICATING THIS POTENTIAL BUT
ALSO MAINTAINS THE PROGRESSIVE LOOK AS WELL. GIVEN MORE UNCERTAINTY
IN THE QPF AMOUNTS AND THERMAL FIELDS, WE DID NOT CHANGE MUCH FROM
CONTINUITY. OVERALL, MAINLY SOME RAIN ACROSS THE SOUTHERN AREAS WITH
THE CHC FOR A WINTRY MIX AT TIMES FARTHER NORTH.
FOR SUNDAY...LOW PRESSURE SHOULD BE EXITING THE MID ATLANTIC COAST
DURING THE MORNING AS A SHORT WAVE TROUGH AMPLIFIES SOME. THERE IS
SOME GUIDANCE THAT SUGGESTS THE SYSTEM IS SLOWER/A BIT STRONGER AND
THEREFORE INTRODUCES MORE PRECIPITATION FOR SUNDAY. AS OF NOW, WE
FOLLOWED HPC`S LEAD AND KEPT THE CONSOLIDATED SURFACE LOW EXITING TO
OUR EAST SUNDAY MORNING. THIS WOULD MEAN PERHAPS SOME PRECIPITATION
TO START, THE HIGH PRESSURE BEGINS TO BUILD IN. THE OVERALL
UPPER-LEVEL TROUGH DOES NOT LOOK TO AMPLIFY MUCH OVER OUR AREA
DURING THIS TIME FRAME, THUS THE FLOW BEING PROGRESSIVE. SOME COOLER
AIR LOOKS TO TRY AND SETTLE SOUTHWARD AS THE SURFACE LOW EXITS,
THEREFORE PERHAPS SOME MIXED PRECIPITATION OR SNOW BEFORE IT ENDS
ACROSS THE NORTH ESPECIALLY. WE DID NOT MAKE TO MANY CHANGES DUE TO
LOWER CONFIDENCE IN THE DETAILS.
FOR MONDAY...THE ACTIVE PATTERN CONTINUES AND THIS FEATURES
AN AMPLIFYING UPPER-LEVEL TROUGH MOVING EASTWARD. THIS WILL DRIVE
LOW PRESSURE ACROSS THE PLAINS MONDAY. THIS SYSTEM LOOKS TO
OCCLUDE WITH ANOTHER SURFACE LOW DEVELOPING FARTHER SOUTH ALONG THE
TRIPLE POINT. THERE IS A DECENT RIDGE BUILDING DOWNSTREAM OF THE
TROUGH, AND THIS WOULD HELP TO PULL MORE MOISTURE NORTHWARD AHEAD OF
THE FRONTAL BOUNDARY. THE LARGE SCALE LIFT LOOKS STRONGER WITH THIS
SYSTEM, AND IT COULD BE ENHANCED SOME AS THE SOUTHERN SURFACE LOW
TRACKS NORTHEASTWARD. WE WENT WITH A DRY MONDAY AS MID LEVEL RIDGING
ARRIVES, ALTHOUGH CLOUDS WILL INCREASE MAINLY LATE.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
THE 06Z TAFS WERE SLIGHTLY FASTER WITH THE PCPN STARTER BUT
OTHERWISE CONTINUE THE IDEAS OF LLWS AND MORE GUSTINESS ALONG WITH
A DROP INTO MVFR LEVELS ONCE PRECIPITATION STARTS.
FOR THE REST OF THE NIGHT INTO THE FIRST PART OF THE MORNING VFR
WITH HIGH CIGS AND NO VSBY RESTRICTIONS. ENOUGH WIND TO PREVENT FOG.
LLWS WAS CONTINUED FROM THE START WITH A SW LLJ AVERAGING 40 TO 45
KTS.
DURING THE SECOND HALF OF THE MORNING WE ARE FORECASTING SHOWERS
TO START SPREADING ACROSS THE TERMINALS AND REACHING ACY BY 18Z.
CONDITIONS WHEN SHOWERS FIRST ARRIVE ARE VFR TO OUR WEST. THE FORECAST
SOUNDINGS ARE SHOWING CONSIDERABLE GUSTINESS. WE WENT WITH THE MORE
CONSERVATIVE SUGGESTION. CONFIDENCE IS LOWER THAN AVERAGE ABOUT THE
WIND GUSTS. UNIDIRECTIONAL SOUTH WINDS, SO ONCE THE GUSTINESS
STARTS, THE LLWS SHOULD END.
DURING THE AFTERNOON WE BROUGHT THE TERMINALS DOWN INTO MVFR AS
THE MORE WIDESPREAD AND HEAVIER SHOWERS MOVE ACROSS THE REGION. AS
THE SHOWERS MOVE IN, THE GUSTINESS SHOULD DECREASE. THERE SHOULD BE
A LULL IN THE WIND ONCE PRECIPITATION MOVES OUT LATE IN THE
AFTERNOON. THIS MIGHT BE A PERIOD WHERE AN IFR CIG OR IFR VSBYS
MIGHT OCCUR. WE LOWERED CIGS AND VSBYS DEEPER INTO MVFR LEVELS BUT
WERE NOT CONFIDENT TO GO IFR.
THE COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA FROM WEST TO
EAST APPROXIMATELY 23Z TO 02Z. ONCE IT DOES, VFR CONDITIONS
SHOULD RETURN, BUT ALSO SOME OCCASIONALLY GUSTY WEST WINDS.
OUTLOOK...
WEDNESDAY...VFR. NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO AROUND
30 KNOTS. SOME SNOW SHOWERS SHOULD BE NORTH AND WEST OF KABE.
THURSDAY...VFR. NORTH-NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO
AROUND 25 KNOTS, DIMINISHING AT NIGHT.
FRIDAY...CLOUDS INCREASE, THEREFORE VFR TO MVFR. SOME RAIN ARRIVES
MAINLY LATER IN THE DAY WITH IFR POSSIBLE, AND THERE COULD BE A
WINTRY MIX FOR A TIME MAINLY NORTH OF A KTTN TO KABE LINE.
EAST-SOUTHEAST WINDS NEAR 10 KNOTS.
SATURDAY...SUB-VFR WITH PERIODS OF RAIN POSSIBLE, WITH PERHAPS A
WINTRY MIX NORTH AND WEST OF KPHL. EASTERLY WINDS NEAR 10 KNOTS,
PROBABLY TURNING NORTHERLY AT NIGHT.
&&
.MARINE...
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH THE SHORT TERM.
WHILE AN APPROXIMATE 50 KT LLJ IS FORECAST TO MOVE OVER THE AREA
WATERS LATER TODAY, THE AIR MASS WILL BE WARMER THAN THE BAY AND
OCEAN TEMPS. SO WE ARE NOT EXPECTING EFFICIENT MIXING. IF WE ARE
WRONG, ITS LIKELY TO BE RIGHT ALONG THE IMMEDIATE COAST. HIGHER
CONFIDENCE ABOUT THE WIND SPEED FORECASTS FARTHER OFFSHORE.
THERE MIGHT BE A LULL IN THE WINDS THIS EVENING AS THE FRONT MOVES
THROUGH, BUT THEN SCA LEVEL WINDS (AS WELL AS SEAS CONTINUING ON THE
OCEAN) SHOULD COME BACK IN FULL SWING AFTER A SMALL TIME GAP.
OUTLOOK...
A COLD NORTHWESTERLY FLOW WILL OCCUR WEDNESDAY AND THURSDAY AS LOW
PRESSURE IS TO OUR NORTHEAST, ALLOWING FOR A TIGHTENED PRESSURE
GRADIENT TO BE IN PLACE. THIS WILL COMBINE WITH CAA, WHICH LOOKS TO
PEAK LATER WEDNESDAY BEFORE SOME MODERATION TAKES PLACE DURING
THURSDAY. THE FORECAST SOUNDINGS SHOW DEEPER MIXING OCCURRING AS WE
GO THROUGH WEDNESDAY, WITH A SOLID SMALL CRAFT ADVISORY EVENT
LOOKING TO OCCUR. THE FORECAST SOUNDINGS ALSO INDICATE THAT SOME
GALE FORCE GUSTS COULD OCCUR, HOWEVER IT LOOKS MARGINAL BASED ON THE
VERTICAL WIND PROFILES. WE THOUGHT ABOUT ISSUING A GALE WATCH FOR
WEDNESDAY NIGHT, HOWEVER WE WOULD LIKE TO SEE HIGHER WINDS WITHIN
THE MIXING LAYER. THEREFORE, WE WILL MAINTAIN THE SMALL CRAFT
ADVISORY BUT EXTEND IT THROUGH 11Z THURSDAY. THIS WILL PROBABLY NEED
TO BE EXTENDED THROUGH THURSDAY AS THE TIGHT PRESSURE GRADIENT HOLDS
FOR A TIME. THE WINDS START DIMINISHING LATER THURSDAY AS HIGH
PRESSURE CENTERED TO OUR NORTH ARRIVES. THE NEXT SYSTEM THOUGH IS
FORECAST TO ARRIVE LATER FRIDAY INTO SATURDAY, WITH WINDS
SHIFTING FROM NORTHERLY TO MORE OF AN EASTERLY DIRECTION.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 6 AM EST
THURSDAY FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...GIGI
SHORT TERM...GIGI
LONG TERM...GORSE
AVIATION...GIGI/GORSE
MARINE...GIGI/GORSE
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
344 AM EST TUE FEB 19 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH LATE TODAY...FOLLOWED BY HIGH
PRESSURE WEDNESDAY AND THURSDAY. A FRONTAL SYSTEM WILL MOVE INTO THE
AREA FOR FRIDAY THROUGH AT LEAST SATURDAY...BRINGING A GOOD CHANCE
FOR RAIN LATE IN THE WEEK INTO THE WEEKEND. HIGH PRESSURE SHOULD
BRIEFLY BUILD IN EARLY NEXT WEEK...BEFORE LIKELY GIVING WAY TO
ANOTHER FRONTAL SYSTEM.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY THIS MORNING...PATCHES OF STRATOCUMULUS CLOUDS IN THE 4 TO 6
KFT RANGE ARE MOVING ACROSS PORTIONS OF THE FORECAST AREA. THESE
CLOUDS...COMBINED WITH LOW LEVEL FLOW FINALLY PICKING UP OUT OF THE
S AND SE HAVE CAUSED TEMPS TO START RISING FROM THEIR EARLIER MINS.
HAVE REMOVED ANY MENTION OF COASTAL SHOWERS AFFECTING THE CHARLESTON
COUNTY BEACHES AS NO SHOWERS HAVE FORMED EVEN OUT TO 40 MILES
OFFSHORE. OTHERWISE...THE COLD FRONT IS STILL WELL TO THE WEST AND
HIGH PRESSURE TO THE EAST.
TODAY...A VIGOROUS CLOSED LOW AND ASSOCIATED MID/UPPER LEVEL TROUGH
WILL MOVE ACROSS THE GREAT LAKES REGION WITH MAINLY JUST SSW FLOW
OVER THE FORECAST AREA. THIS UPPER LEVEL FEATURE WILL DRIVE A SUB
990 MB SURFACE LOW OVER THE GREAT LAKES WITH A TRAILING COLD FRONT
MOVING ACROSS THE TN VALLEY AND THE SOUTHEAST. THIS COLD FRONT WILL
BE THE FORECAST PROBLEM OF THE DAY AND WILL DETERMINE HOW THE
SENSIBLE WEATHER PANS OUT. REGARDING PRECIP CHANCES AND THEIR
TIMING...THE MODELS AGREE IN SHOWING DEEP MOISTURE SPREADING INTO
THE FORECAST AREA WITHIN THE MODERATE DEEP LAYER SW FLOW. PWATS WILL
SURGE TO AROUND 1.10 INCHES IN MOST LOCATIONS WITH SOME VALUES EVEN
APPROACHING 1.25 INCHES IN SE GA. WHILE THIS IS MOIST FOR THIS TIME
OF YEAR...ITS NOT AN ABNORMAL DEGREE OF MOISTURE AND FALLS SOMEWHERE
AROUND THE 75TH PERCENTILE. AS NOTED ABOVE...THE MAIN UPPER LEVEL
ENERGY ASSOCIATED WITH THE TROUGH WILL BE UP ACROSS THE MIDWEST AND
THE GREAT LAKES REGION TODAY. THEREFORE THE UPPER LEVEL SUPPORT IS
SOMEWHAT MUTED THIS FAR SOUTH AND FORCING WILL PRIMARILY BE LIMITED
TO CONVERGENCE ALONG THE APPROACHING COLD FRONT. BASED ON THE LATEST
RUNS OF THE RAP AND OTHER HI-RES MODELS...I HAVE THE BULK OF THE
POPS IN THE FORECAST AREA DURING THE 17-22Z TIME FRAME. THE
CHARACTER OF THE PRECIP IS EXPECTED TO BE SHOWERS. SOUNDINGS DO NOT
YIELD ANY SURFACE BASED INSTABILITY AND LOOKING AT SHOWALTER VALUES
ONLY DEPICTS A SMALL AREA APPROACHING ZERO AROUND SE GA. THUS...THE
FORECAST JUST FEATURES SHOWERS WITH NO THUNDER. TOTAL RAINFALL
AMOUNTS ARE NOT EXPECTED TO BE OVERLY IMPRESSIVE AND SHOULD TOP OUT
AROUND A QUARTER OF AN INCH ACROSS FAR INLAND SE GA. THE FRONT AND
ITS CLOUD COVER WILL MAKE FOR A SOMEWHAT TRICKY MAX TEMP FORECAST.
GIVEN THAT MUCH OF THE CLOUD COVER WITH THE FRONT IS STILL WELL TO
THE WEST...IT STANDS TO REASON THAT MUCH OF THE MORNING WILL SEE AT
LEAST SOME SUNSHINE. WITH LOW LEVEL THICKNESSES SUPPORTING UPPER 60S
TO NEAR 70 WITHIN THE WARM SECTOR...TEMPS SHOULD WARM QUICKLY AFTER
SUNRISE AND THEN SLOW WITH THE ONSET OF THE CLOUD SHIELD. I HAVE
TEMPS RANGING IN THE LOW TO MID 60S...THOUGH SOME LOCATIONS
ESPECIALLY FURTHER EAST...MAY OUTPERFORM THESE VALUES. WITH THESE
TEMPS...WINDS WILL BECOME BREEZY IN THE MORNING...ESPECIALLY ALONG
AND EAST OF I-95.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
TONIGHT...THE FRONT WILL PUSH OFFSHORE QUICKLY WITH COOLER AND DRIER
AIR FILTERING IN. ANY LINGERING SHOWERS SHOULD BE DONE OVER LAND
AREAS BY THE LATE EVENING AND SKIES WILL CLEAR AS WELL. OVERALL THE
AIRMASS BEHIND THE FRONT IS NOT INCREDIBLY COLD. LOWS WILL FALL INTO
THE LOW TO MID 30S INLAND...WITH UPPER 30S TO LOW 40S CLOSER TO THE
BEACHES.
WEDNESDAY...A DEEP CLOSED LOW WILL SHIFT EAST INTO NEW
ENGLAND...WITH A STRONG SHORT WAVE TROUGH FOUND IN THE DESERT SW. IN
BETWEEN A HIGHLY AMPLIFIED RIDGE WILL COVER THE CENTRAL STATES INTO
SOUTH-CENTRAL CANADA. OUR FORECAST ZONES WILL LIE WITHIN A ZONAL
FLOW SOUTH OF THE CYCLONIC FLOW ASSOCIATED WITH THE DEEP LOW MOVING
TOWARD NEW ENGLAND. A SHORT WAVE LOCATED NEAR THE CALIFORNIA BAJA
TODAY WILL BE EMBEDDED WITHIN THE FAST MOVING FLOW ALOFT AND CROSSES
THE REGION LATE IN THE DAY. BUT SINCE THERE IS NO MOISTURE AVAILABLE
FOR IT TO UTILIZE...WITH PWATS NO HIGHER THAN 0.3-0.4
INCHES...RAIN FREE CONDITIONS WILL BE THE RULE. SUNNY SKIES IN THE
MORNING WILL GIVE WAY TO SOME JET STREAK CIRRUS IN THE
AFTERNOON...AS THEY INCREASE AND BECOME A LITTLE MORE OPAQUE LATE.
MODIFIED CANADIAN HIGH PRESSURE WILL BUILD IN AT THE SURFACE FROM
THE NW...ACCOMPANIED BY LOW LEVEL THICKNESSES THAT ARE 15-20 METERS
LOWER THAN TODAY. THIS SUPPORTS AWAY WITHIN A FEW DEGREES EITHER
SIDE OF 60. COASTAL COMMUNITIES THOUGH WILL BE SOME 5-7 DEGREES
COOLER.
THURSDAY...THE CLOSED LOW IN THE MID/UPPER TROPOSPHERE WILL MOVE
INTO THE EASTERN CANADIAN MARITIMES...WITH A NEGATIVELY TILTED
TROUGH SITUATES IN THE CENTRAL PLAINS. IN BETWEEN THESE TWO
FEATURES...THE LOCAL AREA WILL BE UNDERNEATH A HIGHLY AMPLIFIED
RIDGE FROM THE NORTHERN CARIBBEAN SEA TO SOUTH-CENTRAL CANADA.
SURFACE HIGH PRESSURE REMAINS IN CONTROL...BUT BEGINS TO WEAKEN AS
THE SOUTHERN PORTION OF IT SLIDES EAST INTO THE ATLANTIC. AN ONSHORE
RETURN FLOW WITHIN THE COUNTERCLOCKWISE PATTERN AROUND THE HIGH WILL
BRING WITH A SMALL INFLUX OF ATLANTIC MOISTURE...BUT NOT ENOUGH FOR
ANYTHING MORE THAN PATCHY STRATOCUMULUS CLOUDINESS. LOW LEVEL
THICKNESS AND 850 MB TEMPS ARE ON THE RISE...SO A WARMER DAY IS IN
STORE AWAY FROM THE MUCH COOLER COASTLINE...UNLESS JET STREAM CIRRUS
ARE THICKER THAN CURRENTLY ANTICIPATED.
FRIDAY...A SHORT WAVE LIFTING THROUGH THE NORTHERN PLAINS AND UPPER
MS VALLEY...WILL TAKE IT/S SURFACE LOW ALONG WITH IT AS THEY MOVE
NORTH AND NE. EXTENDING SE FROM THE LOW WILL BE A TRIPLE POINT
OCCLUSION IN THE TENNESSEE VALLEY OR IN ALABAMA...A TRAILING COLD
FRONT TO NEAR NEW ORLEANS...AND WARM FRONTOGENESIS OVER OR NEAR THE
LOCAL AREA. NORTH OF THE DEVELOPING WARM FRONT WE WILL BE FORMATION
OF A HIGH PRESSURE WEDGE...WITHIN THE COOL AIR DAMMING EAST OF THE
APPALACHIAN CHAIN. WITH THE GULF AND ATLANTIC OPENED UP WITHIN THE
FIRST 8-10K FEET...CONSIDERABLE MOISTURE WILL SPREAD ACROSS THE SE.
OVER-RUNNING RAINS WILL DEVELOP AS ISENTROPIC UPGLIDE BLOSSOMS AND
PWATS WILL CLIMB TO NEAR 2 STANDARD DEVIATIONS ABOVE NORMAL. RAIN
COVERAGE WILL INCREASE...AND DEPENDING UPON WHERE THE WARM FRONT
ALIGNS ITSELF WE MAY HAVE A SMALL RISK OF THUNDER. RAIN CHANCES WILL
BE HIGHEST OVER THE NW HALF...IN THE RANGE OF 50-60 PERCENT...AND
LOWEST SE PORTION...IN THE RANGE OF 20-30 PERCENT. THE TEMP FORECAST
WILL BE PROBLEMATIC...BUT PRESENT INDICATIONS ARE THAT WITH SOME
SORT OF WEDGE IN PLACE THAT NW SECTIONS WILL STRUGGLE TO GET OUT OF
THE 50S...BUT OUR EXTREME SOUTHERN ZONES MIGHT CLIMB NEAR 70.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
A VERY COMPLEX AND HUGE STORM SYSTEM WILL BE IMPACTING THE EASTERN
HALF OF THE NATION LATE IN THE WEEK...WITH A VERTICALLY STACKED LOW
OVER THE UPPER MIDWEST REGION INTO THE FIRST PART OF THE WEEKEND.
CLOSER TO HOME...AN ELONGATED AND NEARLY STATIONARY FRONT WILL
LINGER OVER OR NEAR THE FORECAST REGION INTO AT LEAST SATURDAY.
VARIOUS SHORT WAVES WITHIN AN ACTIVE SOUTHERN BRANCH OF THE JET
STREAM WILL PERIODICALLY PROGRESS THROUGH THE REGION...CAUSING THE
NEARBY FRONT TO OSCILLATE A LITTLE NORTH AND SOUTH AT TIMES FRIDAY
NIGHT THROUGH SATURDAY NIGHT. WHEN YOU THROW IN A 120-130 KT UPPER
LEVEL JET TO PROVIDE ADDITIONAL FORCING FOR ASCENT...AND PWATS THAT
ARE 2-3 STANDARD DEVIATIONS ABOVE NORMAL...A WET LATE WEEK IS IN
STORE FOR THE ENTIRE FORECAST AREA. RAINFALL TOTALS OF SEVERAL
INCHES MAY OCCUR IN MANY LOCALES...ALTHOUGH DUE TO THE SHOWERY
NATURE OF THE ACTIVITY...ACCUMULATIONS COULD VARY GREATLY FROM ONE
PLACE TO ANOTHER. THE WEDGE SHOWS INDICATIONS OF BREAKING DOWN BY
EARLY SATURDAY...WHICH MAY ALLOW FOR MANY AREAS TO MOVE INTO THE
WARM SECTOR. IF THIS WERE TO OCCUR THEN OUR RISK FOR T-STORMS AND
MAYBE EVEN MARGINALLY SEVERE WEATHER WILL INCREASE. OUR TEMP
FORECAST AGAIN WILL BE A CHALLENGE...SINCE ANY SLIGHT DEVIATION IN
THE FRONTAL POSITION WILL SPELL SIGNIFICANT CHANGES IN OUR LATEST
FORECAST.
AT SOME POINT EARLY NEXT WEEK THERE WILL BE A SOUTHERN STREAM SHORT
WAVE KICKER THAT FINALLY FORCES THE STALLED OUT FRONTAL SYSTEM TO
EXIT THE REGION. AS HIGH PRESSURE BUILDS FROM THE OHIO AND TENNESSEE
VALLEYS WE/LL FINALLY DRY THINGS OUT. THIS MIGHT ONLY BE TEMPORARY
THOUGH...AS THERE MIGHT BE YET ANOTHER RAINMAKER LATE IN THE
FORECAST PERIOD.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
CONDITIONS ARE EXPECTED TO REMAIN PRIMARILY VFR THROUGH 06Z
WEDNESDAY. THE MAIN FORECAST PROBLEM FOR THE NEXT 24 HOURS
REVOLVES AROUND THE APPROACHING COLD FRONT. MAY SEE SOME SCATTERED
STRATOCUMULUS THIS MORNING THROUGH SUNRISE FROM OFF THE NEARBY
MARINE AREAS BUT THIS IS EXPECTED TO REMAIN SCATTERED AT WORST. SW
WINDS WILL BEGIN TO GUST IN THE MID MORNING AND WILL GENERALLY TOP
OUT IN THE 22-24 KT RANGE THROUGH THE AFTERNOON. THE COLD FRONT
AND ASSOCIATED PRECIP WILL MOVE IN DURING THE EARLY AFTERNOON AND
I HAVE KEPT THE 19Z TIMING FROM THE PREVIOUS FORECAST AS IT STILL
LOOKS GOOD. THERE MAY BE BRIEF MVFR LEVEL CONDITIONS WITHIN THE
BAND OF SHOWERS ALONG THE FRONT THIS AFTERNOON...BUT THE
LIKELIHOOD OF EXTENDED PERIODS IS LOW ENOUGH TO KEEP OUT OF THE
FORECAST FOR NOW. THE FRONT AND ASSOCIATED PRECIP WILL PUSH
OFFSHORE IN THE EVENING FOLLOWED BY MORE WESTERLY WINDS AND
CLEARING SKIES.
EXTENDED AVIATION OUTLOOK...PERIODIC FLIGHT RESTRICTIONS ARE LIKELY
IN SHRA AND POSSIBLY EVEN ISOLATED TSRA FRIDAY THROUGH SATURDAY...AS
A FRONTAL SYSTEM IMPACTS THE AIRFIELDS. OTHERWISE...VFR CONDITIONS
WILL PREVAIL.
&&
.MARINE...
TODAY AND TONIGHT...A COLD FRONT WILL APPROACH FROM THE WEST
RESULTING IN A SURGE OF SW FLOW ACROSS THE LOCAL WATERS. ONGOING
SMALL CRAFT ADVISORIES LOOK WELL PLACED...THOUGH I DID ADD ONE TO
THE CHARLESTON HARBOR. AROUND MID MORNING WINDS SHOULD PICK UP AND
FREQUENT 25 KT GUSTS WILL OCCUR OVER THE HARBOR AND AROUND THE
ADJACENT SHORELINE. WINDS WILL BE STRONGEST OVER THE WATERS THROUGH
THE AFTERNOON...WITH A BIT OF A LULL EXPECTED IMMEDIATELY BEHIND THE
FRONT. WINDS WILL THEN PICK UP AGAIN LATE IN THE NW FLOW AND COLD
ADVECTION. IT STILL APPEARS THE OUTER GA WATERS WILL SEE ADVISORY
CONDITIONS LINGER THE LONGEST WHILE THE NEARSHORE WATERS DIMINISH
MORE INTO THE 15-20 KT RANGE LATE. SEAS ARE STILL EXPECTED TO BE 4-6
BEYOND 20 NM AND GENERALLY 3-5 FT WITHIN. HOWEVER...SOME 6 FT SEAS
MAY BE EXPERIENCED AROUND 20 NM OFF THE CHARLESTON COUNTY WATERS.
WEDNESDAY...ANY LINGERING SCA CONDITIONS ACROSS THE OUTER GA WATERS
EARLY ON WILL COME DOWN QUICKLY...AS COLD ADVECTION WANES AND THE
PRESSURE GRADIENT RELAXES WITH HIGH PRESSURE BUILDING FROM THE NW.
IN FACT THE PRESSURE PATTERN RELAXES ENOUGH THAT WEAK RESULTANT SEA
BREEZE CIRCULATIONS LOOK TO DEVELOP IN THE AFTERNOON.
THURSDAY...CONTINENTAL HIGH PRESSURE EARLY WILL SLIDE INTO THE
WESTERN ATLANTIC...AND VEERING WINDS WILL COMMENCE. WINDS AND SEAS
WILL BE ON THE RISE...BUT BELOW ANY HEADLINE CONDITIONS.
FRIDAY THROUGH SATURDAY...WARM FRONTOGENESIS WILL TAKE PLACE ACROSS
THE WATERS FRIDAY...AND THE FRONT WILL LINGER IN OR NEAR THE
IMMEDIATE AREA INTO SATURDAY. MOST OF THE WATERS WILL PROBABLY BE ON
THE SOUTH SIDE OF THE FRONT...BUT WITH A HIGH PRESSURE WEDGE TO BE
FOUND INLAND AND THE FRONT PERHAPS GETTING STUCK UP ON THE COOLER
SHELF WATERS...CHANGES MIGHT BE REQUIRED IN SUBSEQUENT COASTAL
WATERS FORECASTS. BUT SCA CONDITIONS ARE CERTAINLY POSSIBLE AT SOME
POINT LATE IN THE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR AMZ330.
SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR AMZ350-352.
SMALL CRAFT ADVISORY UNTIL 7 AM EST WEDNESDAY FOR AMZ374.
&&
$$
NEAR TERM...BSH
SHORT TERM...33
LONG TERM...33
AVIATION...BSH
MARINE...BSH/33
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1137 PM CST MON FEB 18 2013
...UPDATE TO AVIATION...
.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.
65
&&
.AVIATION...
EXPECT VFR CONDITIONS FOR THE NEXT 24 HOURS.
GARGAN
&&
.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
931 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 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 930 PM MST MON FEB 18 2013
VFR EXPECTED THROUGH THE PERIOD AT KGLD AND KMCK. VRB06 WINDS
EXPECTED AT BOTH SITES THROUGH 17Z OR SO TUESDAY MORNING. FOR
KGLD WIND GUSTS 25-30KTS WILL BE COMMON AFTER 17Z WHILE AT KMCK
EXPECT WINDS 10-15KTS WITH A FEW HIGHER GUSTS. THESE WINDS WILL
CONTINUE AND MAY INCREASE A BIT AFTER 02Z OR SO AS LOW LEVEL JET
STRENGTHENS AND PRESSURE GRADIENT INCREASES AHEAD OF APPROACHING
UPPER TROUGH. SOME CIRRUS TO MOVE OVER FROM THE SOUTHWEST EARLY
TUESDAY MORNING WITH SOME AFTERNOON CU POSSIBLE AS WELL.
&&
.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...99
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
347 AM EST TUE FEB 19 2013
.SHORT TERM... TODAY AND TONIGHT
MILD AND WET CONDITIONS THROUGHOUT SE MICHIGAN DURING THE EARLY
MORNING WILL BE KICKED OUT OF THE AREA BY A STRONG COLD FRONT
PASSING THROUGH AROUND SUNRISE. THE MAIN CONCERN WITH THIS FRONT
WILL BE PEAK WIND GUSTS REACHING 45 MPH ADVISORY CRITERIA IN THE
STRONG WESTERLY FLOW BEHIND IT, BUT THE COMBINATION OF FALLING
TEMPERATURES AND SNOW SHOWERS WILL ALSO ADD A LAYER OF HARSHNESS TO
CONDITIONS THROUGH THE DAY. EXPECT TEMPERATURES TO FALL TOWARD THE
MID AND UPPER 20S BY LATE MORNING, STRUGGLE TO REMAIN IN THE 20S
DURING THE AFTERNOON WITH SINGLE DIGIT WIND CHILL, AND THEN GIVE WAY
TO LOWS WELL DOWN INTO THE TEENS TONIGHT WITH WIND CHILL ABOUT 5
BELOW AFTER MIDNIGHT.
UPSTREAM OBSERVATIONS, ALONG WITH MODEL ISALLOBARIC FIELDS, INDICATE
THE STRONGEST WIND GUSTS OF 40 TO 50 KNOTS OVER CENTRAL INDIANA
OCCURRED WITHIN THE STEEPEST ISALLOBARIC GRADIENT ASSOCIATED WITH A
PEAK 3 HOUR PRESSURE RISE STARTING OFF CLOSE TO 10 MB. THIS PRESSURE
RISE CENTER IS SHOWN TO WEAKEN FROM NEARLY 10 MB TO 3-4 MB IN THE
NAM12 AND HIGH RES RAP MODELS AS THE FRONT MOVES THROUGH WESTERN
LOWER MICHIGAN AND THE REST OF INDIANA AND OHIO. THIS WEAKENING OF
THE ISALLOBARIC COMPONENT OF DYNAMIC FORCING WILL LIKELY RESULT IN A
SHORTER DURATION OF PEAK GUSTS AROUND 45 MPH IN OUR AREA ALONG AND
IMMEDIATELY POST FRONT. AFTER THAT, EXPECT A FEW HOURS OF WIND GUSTS
LESS THAN 40 MPH UNTIL COLD ADVECTION AND SYSTEM RELATIVE ISENTROPIC
DESCENT RAMPS UP LEADING TO STEEPENING LAPSE RATES IN A DEEPENING
BOUNDARY LAYER. DOWNWARD MOMENTUM TRANSPORT WILL THEN BE SUFFICIENT
FOR GUSTS TO REACH 45 MPH AGAIN BY LATE MORNING THROUGH THE
AFTERNOON. GUSTS WILL DIMINISH BY TONIGHT BUT WILL REMAIN IN THE 30
MPH RANGE AS THE BOUNDARY LAYER REMAINS WELL MIXED AFTER SUNSET.
AFTER THE DRY SLOT KEEPS SNOW AT BAY DURING THE MORNING, AN
EXPANSIVE AREA OF MID LEVEL MOISTURE WRAPPING AROUND THE WESTERN
FLANK OF THE LOW WILL DRIVE THE PATTERN OF SNOW DURING THE AFTERNOON
THROUGH TONIGHT. EARLY MORNING RADAR COMPOSITES SHOW THIS COMING
TOGETHER OVER THE UPPER MIDWEST AT PRESS TIME ADDING CONFIDENCE TO
THE EXPECTATION OF A HIGH POP/LOW ACCUMULATION SCENARIO. THIS
MOISTURE WILL SEED ENHANCEMENT FROM LAKE MICHIGAN AS INSTABILITY
INCREASES INTO THE 15-20C RANGE FOR LAKE TO 850 MB DELTA-T. THE MAIN
LIMITING FACTOR WILL BE THE STRONG WIND SPEED AND STEADY VEERING
TREND THAT WILL PREVENT ANY DOMINANT BAND FORMATION. PLAN TO FAVOR
THE TRI CITIES AND THUMB WITH CATEGORICAL POPS DURING THE AFTERNOON
AND LIKELY INTO THE THE EVENING WITH 1 TO 2 INCHES OF ACCUMULATION
BEFORE THE WIND SHIFT TOWARD THE NORTHWEST FAVORS AREAS SOUTH OF
INTERSTATE 69 TOWARD SUNRISE WEDNESDAY.
&&
.LONG TERM...
ALTHOUGH THE 500 MB LOW/MID LEVEL COLD POOL WILL BE MOVING INTO NEW
ENGLAND ON WEDNESDAY...A SHALLOW (SFC-925 MB) BACK DOOR COLD FRONT
WILL ATTEMPT TO MAKE INROADS INTO SOUTHERN LOWER MICHIGAN.
925 MB TEMPS OF -16 TO -17 C FORECASTED TO WORK THROUGH THE THUMB
REGION...WITH LOW LEVEL FLOW JUST SLIGHTLY WEST OF DUE NORTH.
SO...REASONABLE EXPECTATION SOME LAKE EFFECT SNOW SHOWER ACTIVITY
WILL BRUSH THE SHORELINE...BUT SHALLOW NATURE OF THE ACTIVITY
(MODERATING 850 MB TEMPS) SHOULD PREVENT ACTIVITY FROM GETTING OUT
OF HAND. 1042 MB HIGH OVER ONTARIO WILL NOSE INTO SOUTHEAST MICHIGAN
ON THURSDAY...AS AMPLIFIED UPPER LEVEL RIDGE MOVES OVER THE WESTERN
GREAT LAKES. POTENT UPPER WAVE JUST OFF THE PACIFIC NORTHWEST COAST
EARLY THIS MORNING STILL PROGGED TO ROTATE THROUGH THE FOUR CORNERS
REGION LATE WEDNESDAY...BUT TRACKING JUST A TOUCH FARTHER
EAST...OVER/NEAR SIOUX FALLS SOUTH DAKOTA THURSDAY NIGHT (PER 00Z
GFS/EURO). DRAMATIC WEST-EAST SHEARING OF THE UPPER LEVEL
CIRCULATION WILL OCCUR...BUT STILL A PERIOD OF LARGE SCALE ASCENT/PV
ADVECTION FRIDAY MORNING TO OCCUR OVER SOUTHEAST MICHIGAN. THE BULK
OF THE LIFT WILL BE USED UP JUST TO SATURATE THE LOW LEVELS...AS THE
PREVIOUSLY MENTIONED HIGH OVER ONTARIO LEADS TO EASTERLY DRY LOW
LEVEL FLOW PERSISTING INTO FRIDAY. 00Z GFS NOT EVEN GIVING US A
TENTH OF AN INCH OF QPF...AS DEEPER MOISTURE SEEN IN THE 850-700
MB/PW FIELDS SKIRTS JUST TO THE SOUTHEAST OF THE CWA. STILL...DECENT
SHOT OF MOISTURE ADVECTION...AND PREFERENCE IS WITH THE STRONGER
CANADIAN/EURO WHICH MAINTAINS THE 500 MB LOW OVER MINNESOTA INTO THE
FIRST HALF OF THE WEEKEND. QPF FROM THOSE MODELS SUPPORTS A SOLID 1
TO TWO INCHES OF SNOW ON FRIDAY...WITH RELATIVELY LOW SNOW TO LIQUID
RATIOS...AS ZERO OR SLIGHTLY BETTER 850 MB TEMPS SEEN REACHING THE
OHIO BORDER.
THE MODEST MID LEVEL COLD POOL OVER MINNESOTA WILL BREAK OFF TO THE
EAST FOR THE WEEKEND...KEEPING TEMPERATURES IN CHECK...AS 850 MB
TEMPS LOOK TO BE HOVERING AROUND -10 C...AND WITH LIMITED
SUNSHINE...MAXES EXPECTED TO REMAIN GENERALLY BELOW 40 DEGREES.
ALTHOUGH...WE WILL HAVE THE DRY SLOT WORKING THROUGH SATURDAY
MORNING...WHICH COULD BE THE DAY WE SNEAK UP TO 40 DEGREES.
&&
.MARINE...
DEEP LOW PRESSURE MOVING THROUGH THE STRAITS WILL PULL A STRONG COLD
FRONT THROUGH LAKE HURON AND LOWER MICHIGAN EARLY IN THE MORNING.
WESTERLY GALES WILL DEVELOP AFTER THE FRONTAL PASSAGE AND THEN
PERSIST TONIGHT THROUGH WEDNESDAY WHILE VEERING TO NORTHWEST OVER
THE OPEN WATERS OF LAKE HURON. POLAR AIR SURGING BACK INTO THE
REGION WILL CHANGE RAIN BACK TO SNOW AND ALSO LEAD TO A SUBSTANTIAL
FREEZING SPRAY HAZARD OVER THE OPEN WATERS TONIGHT THROUGH
WEDNESDAY. THE STRONG WINDS AND RESULTING LARGE WAVES WILL COMBINE
WITH NEAR IDEAL WATER TEMPERATURE FOR WIDESPREAD FREEZING SPRAY TO
BECOME HEAVY. MARINE CONDITIONS WILL THEN IMPROVE CONSIDERABLY BY
THURSDAY AS HIGH PRESSURE SETTLES OVER THE REGION.
&&
.AVIATION...ISSUED 1150 PM EST MON FEB 18 2013
//DISCUSSION...
RAIN SHOWERS WILL BECOME MORE NUMEROUS AS THIS FORECAST PERIOD
BEGINS AS MOISTURE CONVERGENCE IN ADVANCE OF APPROACHING COLD FRONT
SHIFT INTO THE AREA. WITH THIS ACTIVITY...CIGS WILL FALL TO MVFR TO
OCCASIONAL IFR...ESPECIALLY RIGHT ALONG THE FRONT...WHICH WILL PASS
THROUGH BETWEEN 10Z-12Z. RAIN SHOWERS WILL CHANGE TO SNOW WITHIN
COLD AIR ADVECTION BEHIND THE FRONT...AND WEST/SOUTHWEST WINDS WILL
BECOME VERY STRONG WITH GUSTS TO 30-35 KNOTS ON TUESDAY.
FOR DTW...CIGS WILL FALL BELOW 5000 FEET AT THE BEGINNING OF THE
FORECAST AND THEN BOTTOM OUT BETWEEN 900-1800 FEET IN ADVANCE OF
COLD FRONT BEFORE LIFTING BACK TO MVFR/LOWER VFR ON TUESDAY AS GUSTY
(25-35 KT) WEST/SOUTHWEST FLOW DEVELOPS. RAIN SHOWERS TONIGHT
WILL CHANGE TO SCATTERED LIGHT SNOW SHOWERS.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET MUCH OF THE FORECAST.
* HIGH CONFIDENCE IN RAIN AS PRECIPITATION TYPE TONIGHT...CHANGING
TO SNOW SHOWERS AROUND 11Z-12Z TUESDAY.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055-MIZ060-
MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075-MIZ076-MIZ082-
MIZ083...UNTIL 7 PM TUESDAY.
LAKE HURON...
GALE WARNING...LHZ361...FROM NOON TUESDAY TO 7 PM WEDNESDAY.
HEAVY FREEZING SPRAY WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-
LHZ464...FROM 7 PM TUESDAY TO 7 PM WEDNESDAY.
GALE WARNING...LHZ362-LHZ363...FROM 7 AM TUESDAY TO 7 PM WEDNESDAY.
GALE WARNING...LHZ421-LHZ422-LHZ441-LHZ442-LHZ443-LHZ462-LHZ463-
LHZ464...FROM 7 AM TUESDAY TO MIDNIGHT WEDNESDAY.
LAKE ST CLAIR...
GALE WARNING...FROM 7 AM TUESDAY TO MIDNIGHT WEDNESDAY.
MI WATERS OF LAKE ERIE...
GALE WARNING...FROM 7 AM TUESDAY TO MIDNIGHT WEDNESDAY.
&&
$$
SHORT TERM...BT
LONG TERM....SF
MARINE.......BT
AVIATION.....DG
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DULUTH MN
321 AM CST TUE FEB 19 2013
.CURRENT...VERY DEEP MID LVL TROF CONTINUES TO AMPLIFY AS IT CRAWLS
ACROSS CWA EARLY THIS MORNING. SFC LOW OVER ERN WISC IS INTENSIFYING
AS IT MOVES TOWARDS ERN END OF LAKE SUPERIOR. LARGE SHIELD OF DEEP
LAYER MOISTURE ACCOMPANIED BY COLD ADVECTION IS KEEPING LIGHT SNOW
ACROSS REGION. A STANDING WAVE IS INDICATED... ACROSS DOUGLAS COUNTY
AND INTO SE CARLTON COUNTY NEAR HOLYOKE... IN THE ANIMATED 88D
REFL/VEL PRODUCTS AS NW FLOW INCREASES. SFC PRESS GRADIENT NEARLY
20MB ACROSS CWA WITH GUSTY WINDS ACROSS MOST OF MN ZONES. VERY
STRONG GUSTS ALONG NORTH SHORE FROM TWIN PORTS TO GRAND PORTAGE.
LOCAL KATABATIC ENHANCEMENT OCCURING FROM SILVER BAY NORTH TO BORDER
WHERE INLAND TERRAIN IS HIGHER. GUST OVER 50 MPH HAVE OCCURED IN
THIS CORRIDOR WITH HRRR 3KM OUTPUT SUGGESTING GUSTS MAY REACH 60 MPH
THROUGH EARLY MORNING. ARCTIC AIR HAS INFILTRATED THE NORTHWESTERN
CWA WITH SFC TEMPS BELOW ZERO. WINDCHILL ADVISORY MAY NOT VERIFY IN
MANY AREAS UNTIL BETWEEN 12Z-15Z WHEN MIN TEMPS ARE REACHED AND WIND
SPEEDS REMAIN RELATIVELY HIGH. .
TODAY/TONIGHT...SLOW MOVING MID LVL TROF WILL KEEP A CYCLONIC AND
RELATIVELY MOIST CIRCULATION OVER THE REGION. GUSTY WINDS ARE EXPECTD
TO CONTINUE AS SFC PRESS GRADIENT REMAINS QUITE LARGE ACROSS CWA.
BUFKIT MOMENTUM TRANSFER PROFILES SHOW GUSTS MAY LINGER WELL INTO
THE NIGHT AS WELL. NORTH SHORE STILL SUSCEPTIBLE TO KATABATIC
ENHANCEMENT OFF HIGHER PLATEAU WEST OF LAKE SUPERIOR...ESPECIALLY
COOK COUNTY THROUGH MID MORNING. DEEP LAYER DRYING WILL OCCUR FROM
WEST TO EAST TODAY OVER THE MN ZONES. MAIN STORY OVER WISC WILL BE
CONTINUATION OF LES ACROSS SNOW BELTS. LAKE INDUCED CAPE FORECAST
TO INCREASE TO 400/500 J/KG THIS AFTN. INVERSION HEIGHTS ARE
EXPECTED TO LIFT TO ABOUT 4K FT THIS AFTERNOON BEFORE LOWERING TO 2K
FT AFTER MDINIGHT TONIGHT. WILL KEEP CURRENT ADVISORY/WARNING FOR
SOUTH SHORE. WILL NEED ANOTHER WIND CHILL ADVISORY TONIGHT FOR MOST
OF CWA. WILL LET DAY SHIFT ISSUE THIS AFTER CURENT WINDC ADV EXPIRES.
MAX TEMPS TODAY WILL STRUGGLE ALL DAY TO GET ABOVE ZERO ACROSS THE
BORDERLAND AND IRON RANGE. SINGLE DIGITS ELSEWHERE. LOWERED PREVIOUS
TEMP FCST OVER INTERIOR WISC IN LINE WITH ECBC VALUES AND LOWER
TEMPS OF SREF PLUMES.
TOMORROW...PROGRESSIVE FLOW ALOFT WILL SEND A MID LVL RIDGE
OVERHEAD. STRONG SFC HIGH CENTERED OVER NRN ONTARIO WILL BUILD SOUTH
INTO CWA. ABUNDANT SUNSHINE TO START THE DAY ALTHOUGH HIGH CLOUDS
MAY INCREASE FROM THE SOUTHWEST IN THE AFTERNOON IN RESPONSE TO
UPPER LEVEL WARM ADVECTION FROM SRN ROCKIES STORM. TEMPS REMAIN
WELL BELOW CLIMO.
LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY.
FOCUS IN LONG TERM ON ACTIVE PATTERN FOR THE UPPER MIDWEST LATE IN
THE WEEK...AND EARLY NEXT WEEK.
UPPER LEVEL RIDGE WILL AMPLIFY OVER THE WRN GREAT LAKE REGION WED
NIGHT AS A VORT MAX ROUNDS THE BASE OF A LONG WAVE TROUGH IN THE SW
CONUS...DEEPENING INTO A CLOSED LOW AS IT LIFTS ACROSS THE CENTRAL
PLAINS THURSDAY. THE 00Z MODELS ARE SHOWING GOOD AGREEMENT THAT THE
H50 LOW PUSHES INTO THE SRN DAKOTAS/MINN THURSDAY
EVENING...CENTERING OVER MINNESOTA FRIDAY NIGHT. MEANWHILE...THE SFC
LOW REMAINS TO THE SW OF THE H50 LOW...TRACKING ACROSS IOWA THROUGH
THE DAY FRIDAY...REACHING UPPER MICHIGAN/CEN GREAT LAKES FRIDAY
NIGHT. HAVE MADE VERY LITTLE CHANGES TO POPS THURSDAY NIGHT/FRIDAY
AS THE LEADING EDGE OF THE MAIN SWATH OF SNOW IS EXPECTED TO IMPACT
THE SRN DLH ZONES THURSDAY EVENING...LIFTING OVER MUCH OR ALL OF THE
NORTHLAND THROUGH FRIDAY. TEMPERATURE PROFILES CONTINUE TO SUGGEST
PTYPE OF ALL SNOW FOR THE DLH CWA.
ALTHOUGH UNCERTAINTY REMAINS...MODELS HAVE SHOWN DECENT RUN TO RUN
AGREEMENT THAT A BAND OF HEAVY SNOW DEVELOPS ACROSS THE SRN HALF OF
MINNESOTA THURSDAY NIGHT INTO FRIDAY MORNING. LATEST GFS/ECM
CONTINUE TO SHOW VERY DRY AIR ASSOCIATED WITH A RIDGE AXIS EXTENDING
SOUTH FROM ONTARIO WILL BE DIFFICULT TO ERODE THURSDAY NIGHT...SO
HAVE TRENDED A WITH A SLOWER TIMING FOR INTRODUCING POPS. THE LATEST
NAM BUFR SOUNDING AT KBRD/KINL/KHYR DEPICT PWATS INITIALLY THURSDAY OF
ONLY 0.08". HOWEVER...THERE IS MOISTURE ASSOCIATED WITH THE LOW THAT
DOES ADVECT INTO THE REGION AS THE H50 LOW APPROACHES...ALLOWING
PWATS TO INCREASE TO AROUND 0.3" THROUGH FRIDAY NIGHT AT MOST
LOCATIONS.
HAVE INCREASED TO BROADBRUSH LIKELY POPS FOR LIGHT SNOW FRIDAY.
MODELS SUGGEST THE H50 LOW HANGS AROUND THE GREAT LAKES REGION
THROUGH THE WEEKEND...KEEPING CYCLONIC FLOW...CLOUDS AND LIGHT SNOW
CHANCES FOR THE NORTHLAND.
ALTHOUGH THE GFS IS SHOWING A TREND TOWARDS THE ECM SOLUTION FOR THE
SYSTEM THAT WILL IMPACT THE REGION EARLY NEXT WEEK...THERE REMAINS
LARGE DIFFERENCES IN TIMING AND STORM TRACK. THE ECM SOLUTION LIFTS
THE CLOSED LOW OVER THE DAKOTAS TUESDAY...WHILE THE LATEST GFS
SUGGESTS A FASTER AND MORE EASTERLY TRACK WITH THE H50 LOW PASSING
OVER MINN/WIS MONDAY NIGHT.
.AVIATION...06Z TAFS
MOSTLY MVFR CEILINGS COVERED THE NORTHLAND LATE THIS EVENING...BUT
THERE WERE SOME VFR CEILINGS THAT WERE OCCURRING AS WELL.
FOLLOWING CLOSER TO THE RAP/S 925-950MB CONDENSATION PRESSURE
DEFICITS...WHICH ARE DOING AN OK JOB...KEEPS MOSTLY MVFR CEILINGS
TONIGHT INTO TUESDAY MORNING...BEFORE WE SEE SOME IMPROVEMENT.
THERE MAY CONTINUE TO BE POCKETS OF VFR CONDITIONS OVERNIGHT
THOUGH.
STRONG NORTHWEST WINDS WILL CONTINUE THROUGH MUCH OF THE
PERIOD...STRONGEST AROUND LAKE SUPERIOR.
.POINT TEMPS/POPS...
DLH 4 -12 13 4 / 20 10 0 0
INL 1 -24 8 -11 / 10 10 0 0
BRD 4 -14 13 -3 / 10 10 0 0
HYR 8 -14 15 -8 / 30 10 0 0
ASX 10 -8 15 -1 / 60 40 20 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WIND CHILL ADVISORY UNTIL NOON CST TODAY FOR MNZ010>012-018>021-
025-026-033>037.
WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR WIZ004.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ002.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ003.
&&
$$
SHORT TERM...CANNON
LONG TERM....GRANING
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1247 AM EST TUE FEB 19 2013
.SYNOPSIS...
A STRONG COLD FRONT WILL CROSS THE OHIO VALLEY TONIGHT. HIGH
PRESSURE WILL SETTLE OVER THE MIDWEST WEDNESDAY AND THE RIDGE WILL
WORK INTO THE OHIO VALLEY WEDNESDAY NIGHT. AN ELEVATED WARM FRONT
WILL MOVE NORTH THROUGH THE AREA INTO THE GREAT LAKES REGION ON
THURSDAY NIGHT AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A COLD FRONT WAS MOVING ACROSS ILLINOIS LATE THIS EVENING. THIS
BOUNDARY WILL TRACK ACROSS THE REGION OVERNIGHT AND BE NEAR THE
EASTERN EDGE OF THE FORECAST AREA BY DAYBREAK. SHOWERS AHEAD OF
THE FRONT WERE MOVING INTO THE WESTERN COUNTIES AND WILL CONTINUE
EAST. HRRR AND RAP GUIDANCE HAVE BEEN SUGGESTING THAT SHOWERS WILL
COME IN A COUPLE OF WAVES. INITIALLY ACTIVITY WILL BE WIDESPREAD
BUT THEN DIMINISH IN COVERAGE LATER TONIGHT. APPEARS THAT A NARROW
LINE COULD THEN COME THROUGH WITH THE ACTUAL BOUNDARY. SOUTH WINDS
WILL REMAIN GUSTY THROUGH THE NIGHT. BUT STRONGER GUSTS HAVE BEEN
OCCURRING IMMEDIATELY AHEAD OF THE PRECIPITATION WHERE LIGHTER MID
LEVEL ECHOES HAVE BEEN FALLING INTO DRIER AIR. TEMPERATURES SHOULD
REMAIN QUITE MILD THROUGH MOST OF THE NIGHT WITH ONLY A SLIGHT
DROP UNTIL THE FRONT MOVES THROUGH AND THEN READINGS WILL START
TO FALL QUICKLY.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/...
COLD AIR BEHIND THE FRONTAL PASSAGE IN THE MORNING WILL RESULT IN
FALLING TEMPERATURES DURING THE DAY. NOT TOO MUCH MOISTURE WILL BE
AROUND BUT SOME SCATTERED SNOW SHOWERS WILL OCCUR OVER THE
NORTHERN HALF OF THE CWA TUESDAY AFTERNOON IN THE CYCLONIC FLOW
CAPTURING SOME MOISTURE OFF OF LAKE MICHIGAN AND INTERACTING WITH
THE THERMAL DIFFERENCES AND COLD AIR ALOFT.
SKIES SHOULD CLEAR OVERNIGHT AS NORTHWEST WINDS CONTINUE TO PUSH
COLDER AIR INTO THE REGION.
FAIR WEATHER CU WILL POP UP ON WEDNESDAY AND AS THE RIDGE OF HIGH
PRESSURE SETTLES OVER THE OHIO VALLEY IT WILL SET UP A TYPICAL
PATTERN FOR RADIATIONAL COOLING. TEMPERATURES TUESDAY NIGHT AND
WEDNESDAY NIGHT WILL BE IN THE TEENS ON BOTH NIGHTS BUT OCCUR FOR
DIFFERENT REASONS...ADVECTION ON WED MORNING AND RADIATION THURS
MORNING.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
FIRST PART OF THE FORECAST PERIOD WILL BE BUSY AS A STORM SYSTEM
LIFTS OUT OF THE PLAINS. AREA OF HIGH PRESSURE WILL BE CENTERED
ACROSS THE REGION THURSDAY MORNING. 12Z MODEL RUNS ARE SHOWING THE
HIGH WILL BE SLOWER IN RETREATING THURSDAY...WHICH WILL DELAY THE
ONSET OF THE PRECIPITATION THU AFTN. SO HAVE BACKED OFF TO JUST SLGT
CHC POPS SW OF CVG FOR THU. WITH THE HIGH HOLDING STRONGER...THU IS
LOOKING COOLER AND THEREFORE THE OVERALL MODEL PROFILES LOOK COLDER.
THIS IS INDICATING MORE SNOW AND POSSIBLY FREEZING RAIN AND A SLOWER
CHANGE OVER TO LIQUID RAIN LATE THU NGT INTO FRI.
BEST LIFT AND QPF ARE STILL FORECAST TO LIFT N OF THE REGION ON
FRIDAY...AS A WRMFNT GRADUALLY BRINGS IN WARMER AIR ON FRI.
AS MENTIONED YESTERDAY...SECONDARY SYSTEM THAT WAS LIFTING ACROSS
THE SE U.S. OVER THE WEEKEND HAS TRENDED NWD FOR FRI NGT INTO SAT...
SO INTRODUCED CHC POPS FOR THE SE COUNTIES. RIGHT NOW THE PCPN TYPE
LOOKS LIKE RAIN. HIGH PRESSURE LOOKS LIKE IT WILL FINALLY BUILD IN
FOR SUNDAY. ANOTHER CDFNT IS FORECAST TO SWING INTO THE OH VALLEY
MONDAY...BUT THE GFS AND ECMWF ARE SHOWING DIFFERENCES...SO RIGHT
NOW JUST HAVE A MENTION OF CHANCE POPS FOR MONDAY.
THE COOL SE FLOW ON THU WILL KEEP HIGHS IN THE 30S. LOWS THU NGT IN
THE STORM SHOULD RANGE FROM THE MID 20S IN THE N TO LOWER 30S IN NRN
KY. HIGHS FRIDAY SHOULD MAKE THE 40S AS THE REGION GETS WARM
SECTORED. SOME LOCATIONS IN THE NRN KY MIGHT SEE 50S. EXPECT 40S
OVER THE WEEKEND FOR HIGHS WITH LOWS IN THE UPPER 20S TO LOWER 30S
SATURDAY MORNING AND 25 TO 30 SUNDAY MORNING. HIGHS SHOULD BEGIN TO
WARM FOR SUNDAY AND MONDAY REACHING THE MID 40S TO MID 50S BY MONDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
COLD FRONT IS EVIDENT ON RADAR PUSHING ACROSS WESTERN INDIANA
ATTM. CURRENT TIMING HAS IT TO THE WESTERN TAF SITES BETWEEN 09Z
AND 10Z AND THE EASTERN TAF SITES AROUND 11Z TO 1130Z. WIDESPREAD
PCPN WILL CONTINUE OUT AHEAD OF THE FRONT WITH VFR CIGS DROPPING
TO MVFR A COUPLE OF HOURS AHEAD OF FROPA. WE HAD SOME ENHANCED
HIGHER GUSTS ALONG THE LEADING EDGE OF THE PCPN DUE IN PART TO
THE DRY LOW LEVELS. NOW THAT WE HAVE MOISTENED UP...EXPECT GUSTS
GENERALLY IN THE 25 TO 30 KNOT RANGE AHEAD OF THE FRONT. A NARROW
LINE OF STRONGER SHOWERS RIGHT WITH THE FRONT COULD BRIEFLY DROP
VSBYS TO IFR BUT RAIN SHOULD THEN END QUICKLY AS DRIER AIR MOVES
IN BEHIND THE FRONT. WINDS WILL SWING AROUND TO THE WEST AND
REMAIN GUSTY THROUGH THE REST OF THE DAY WITH CIGS GENERALLY
REMAINING MVFR.
OUTLOOK...A WINTRY MIX IS LIKELY TO OCCUR THURSDAY NIGHT INTO
FRIDAY MORNING WITH SOME SNOW AND ICE ACCUMULATION POSSIBLE. IN
ADDITION MVFR CEILINGS AND VISIBILITIES WILL BE LIKELY WITH A
PERIOD OF IFR CONDITIONS POSSIBLE. MVFR CEILINGS MAY CONTINUE
THROUGH FRIDAY NIGHT AND INTO SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WIND ADVISORY UNTIL 2 AM EST EARLY THIS MORNING FOR OHZ026-034-
035-042>046-051>056-060>065-070>074-077>082-088.
KY...WIND ADVISORY UNTIL 2 AM EST EARLY THIS MORNING FOR KYZ092-093-
096>100.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...
SHORT TERM...FRANKS
LONG TERM...SITES
AVIATION...JGL
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1148 PM EST MON FEB 18 2013
.SYNOPSIS...
A COLD FRONT IS GOING TO MOVE FROM THE MISSISSIPPI VALLEY TONIGHT
INTO THE CENTRAL APPALACHIANS BY LATE TUESDAY MORNING...AND
THROUGH OUR AREA BY TUESDAY EVENING.
HIGH PRESSURE WILL WORK IN FROM THE UPPER MIDWEST WEDNESDAY
SLIDING EAST OVER THE AREA BY THURSDAY MORNING.
&&
.NEAR TERM /THROUGH TUESDAY/...
AS OF 810 PM EST MONDAY...
CONVECTIVE BAND NOW EAST OF THE MISS RIVER REMAINS THE MAIN
CONCERN LATER TONIGHT AS IT ZIPS EAST AND ENCOUNTERS RESIDUAL
COLD/DRY AIR STILL LOCKED IN ACROSS THE REGION. TIMING/QPF THE
MAIN ASPECTS ACROSS THE WESTERN THIRD BY MORNING...AND EAST OF THE
BLUE RIDGE EARLY TUESDAY. LATEST NAM AND RAP REMAIN A BIT SLOW
WITH INIT ON CURRENT AXIS OF PRECIP TO THE WEST...SO PLANNING TO
STAY FASTER WITH ARRIVAL ESPCLY GIVEN SUCH A STRONG 3H JETLET
PASSING THRU THE BOTTOM OF THE UPPER TROF JUST WEST OF THE
MOUNTAINS BY DAYBREAK. LATEST FORECAST SOUNDINGS SUGGEST QUICK WET
BULBING DOWN TO AN ISOTHERMAL LAYER AROUND FREEZING WESTERN HALF
LATE WITH VERY LITTLE WARM NOSE SUPPORTIVE OF MORE SLEET/SNOW
EXCEPT PERHAPS THE FAR SW WHERE THE BOUNDARY LAYER MAY BE A BIT
WARM FOR LITTLE MORE THAN RAIN/SLEET. LATEST LOCAL RNK WRK ALSO
SHOWING HEAVIER BANDS OF PRECIP FAR WEST AT THE ONSET SO MAIN
CHANGE WAS TO UP QPF ALONG/WEST OF THE I-77 CORRIDOR BY 12Z...AND
BOOST POPS/SNOWFALL FOR THE NW NC RIDGES INTO GRAYSON WHERE 1-2+
INCHES LOOK POSSIBLE BEFORE PRECIP TAPERS OR GOES TO -DZ TUESDAY.
ELSW STILL THINKING A MIXED BAG...BUT LIKELY MORE SNOW IN THE
TYPICAL DEEPER WEDGE AREAS...WITH SOME FREEZING RAIN POSSIBLE
VALLEYS EARLY TUESDAY AFTER SURFACE TEMPS HAVE BEEN BRIEFLY COOLED
BELOW FREEZING.
TIMING EAST OF THE ADVISORY CRITICAL IN WHETHER OR NOT ANYTHING
FROZEN OCCURS OR IS MOSTLY A RAIN EVENT WITH SOME SLEET AT THE
ONSET ESPCLY IF ARRIVAL IS AN HOUR OR TWO AFTER DAYBREAK. COULD
POSSIBLY SEE LOCATIONS ON THE VIRGINIA SIDE...OUT EAST OF THE
HIGHER RIDGES TO HIGHWAY 29...GET A QUICK SLEET/SNOW COATING BUT
ONLY IF PRECIP IS FASTER. OTRW MOSTLY LIGHT QPF AND LIQUID AT
THIS POINT.
SOUTH WINDS JUST AHEAD OF THE FRONT STILL LOOK CLOSE TO WARNING
CRITERIA TAZEWELL/BLF REGION PER LATEST MODEL CROSS SECTIONS.
HOWEVER LIKELY ONLY A QUICK BURST RIGHT AHEAD OF THE PRECIP
LATE GIVEN THE FLOW TURNING MORE SW...AND THEN PERHAPS STRONGER
LATER TUESDAY BEHIND THE FRONT WHEN MOMENTUM TRANSFER IS BETTER
OUTSIDE OF THE RAIN/SNOW. THUS WILL KEEP GUSTS TO HIGH END
ADVISORY WITHIN THE WINTER WEATHER PRODUCT FOR THE OVERNIGHT AT
THIS POINT.
TEMPS SLOW TO FALL THIS EVENING OUTSIDE THE VALLEYS WITH A DECENT
SOUTH WIND KICKING IN WELL AHEAD OF THE FRONT. THEREFORE ADJUSTING
THE TEMP CURVE A BIT TO REFLECT COLDER VALUES MORE WITH PRECIP
LATER THAN EARLY RAD COOLING. HOWEVER DEWPOINTS REMAIN DRY ENOUGH
TO WET BULB DOWN TO THE LOW/MID 30S UNLESS THE WARM ADVECTION IS
JUST TOO STRONG...AND THE INIT PRECIP LIGHT...ALLOWING A QUICK
RISE IN DEWPOINT DEPRESSIONS LATE THUS CUTTING INTO WET BULB
COOLING SOMEWHAT.
PREVIOUS DISCUSSION...
EXPECTING A NUISANCE TYPE WINTER WEATHER EVENT LATE TONIGHT INTO
LATE TUESDAY MORNING...WHICH ALTHOUGH AMOUNTS OF WINTRY WEATHER
WILL NOT BE REACHING OUR ADVISORY LEVELS PER SE...THE MORNING
COMMUTE WILL BE WHEN MOST OF THIS WILL BE OCCURRING...HENCE THE
ADVISORY. NOT TOO IMPRESSED WITH FREEZING RAIN CHANCES...DESPITE
THE STRONG LOW LVL JET ARRIVING LATE TONIGHT. ATTM...MODEL
SOUNDINGS FORECAST ENOUGH DRY AIR AND SUB-FREEZING WET BULBS THAT
WHEN PRECIPITATION ARRIVES ACROSS MOST OF THE AREA IT SHOULD START
AS SNOW. EXCEPTION WILL BE ACROSS THE FAR WRN ZONES WHERE MORE OF
SW WIND WILL HELP KEEP THE LOW LVLS WARMER WITH RAIN MIXING IN.
MADE NO CHANGES TO THE ADVISORY...EXCEPT ADDING THE MENTION OF
HIGHER WIND GUSTS OVER THE TYPICAL AREAS FROM BLF-MOUNT ROGERS.
THE 8H JET OF 60 KNOTS AND SFC WINDS OUT OF THE SSE ARE USUALLY
ENOUGH TO GIVE THE CLINCH RIVER VALLEY/BURKES GARDEN AND OTHER
AREAS AROUND THE MOUNTAIN EMPIRE STRONG WIND GUSTS. ATTM...DO NOT
SEE A HIGH WIND WARNING ALTHOUGH WOULD NOT BE SURPRISED IF PLACES
LIKE MOUNT ROGERS OR BURKES GARDEN EXPERIENCE GUSTS OVER 58 MPH.
SOME SMALL TREES AND LIMBS WILL BE FALLING...WITH ISOLATED POWER
OUTAGES POSSIBLE.
GOING TOWARD THE MODEL MEAN OF THE NAM/GFS SHOWS THE FRONT PUSHING
ACROSS THE BLUE RIDGE BY EARLY AFTERNOON. HAVE PRECIP CHANGING TO
MORE RAIN BEFORE THEN WITH SNOW LINGERING OVER THE HIGHER
ELEVATIONS...BECOMING MORE SHOWERY AFTER FRONTAL PASSAGE. THINGS
DRY OUT BY THE AFTERNOON IN THE SOUTHWEST WITH A QUICK DRYING
ARRIVING ELSEWHERE BY THE END OF THE DAY. WINDS ARE GOING TO SHIFT
WEST AND GUST OVER 40 MPH AT TIMES...BUT NOT GOING WITH WIND
ADVISORY AS 8H WINDS ARE NOT AS STRONG...PER NAM/GFS.
TEMPS WILL BE FALLING QUICK THIS EVENING BEFORE CLOUDS
ARRIVE...THEN STEADY OR RISE AFTER MIDNIGHT BEFORE FALLING AGAIN
WHEN PRECIP ARRIVES IN THE WEST BY DAWN. THIS WILL BE PROBLEMATIC
WITH SFC TEMPS AND THE WINTRY PRECIP.
DESPITE THIS WINTRY EVENT...TEMPS TUESDAY WILL BE SEASOANAL WITH
40S WEST AND LOWER 50S EAST.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
AS OF 300 PM MONDAY...
STRONG COLD FRONT WILL BE WELL EAST OF THE CWA TUE NIGHT WITH STRONG
COLD AIR ADVECTION IN ITS WAKE. A FEW LINGERING MOUNTAIN SNOW
SHOWERS POSSIBLE IN MOST FAVORED UPSLOPE AREAS BUT OTHERWISE WINDY
AND COLD WITH CLEARING SKIES OVERNIGHT. H85 TEMPS FALL BACK TO -10C
TO -15C RANGE BY 12Z WED...WITH LOW TEMPS LIKELY TO BE UPPER TEENS
NW TO MID-20S EAST. 12Z NAM ALSO SHOWS NW WINDS AT H85 IN THE 50-60
KT RANGE EARLY WED MORNING WHICH MAY WARRANT A WIND
ADVISORY...ESPECIALLY ALONG EXPOSED RIDGETOPS. EITHER WAY WILL BE A
VERY CHILLY START TO THE DAY. WITH GRADIENT BETWEEN DEPARTING
SURFACE LOW OVER THE MARITIMES AND 1040 MB RIDGE OF HIGH PRESSURE
BUILDING SOUTHEAST FROM THE UPPER PLAINS WED LOOKS TO REMAINS
BREEZY...ALBEIT WINDS SLOWLY DIMINISHING. TEMPS RANGE FROM UPPER 20S
NW TO LOW 40S SE..ROUGHLY 10-12F BELOW MID TO LATE FEB. CLIMATOLOGY.
STRONG SURFACE RIDGE IS MAINTAINED ACROSS THE MID-ATLANTIC REGION
MOST OF THURSDAY AS A NEW STORM SYSTEM BECOMES ORGANIZED IN THE LEE
OF THE ROCKIES AND BEGINS TO LIFT OUT ACROSS THE MIDWEST AS A MAJOR
WINTER STORM WITH POSSIBLE SEVERE WX ACRS PARTS OF TEXAS. COLD AIR
DAMMING WILL BEGIN TO DEVELOP THURSDAY EVENING.NIGHT ALONG THE EAST
COAST FROM THE SAME SURFACE HIGH SLIDING EASTWARD. MEANWHILE FAST
WSW FLOW ALOFT BRINGS MOISTURE RAPIDLY NORTHEASTWARD AND LIKELY
OVERRUNNING THE COOL WEDGE WITH LIKELY P-TYPE FORCAST ISSUES AS
EARLY AS THURSDAY NIGHT.
.LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 328 PM EST SUNDAY...
SURFACE HIGH PRESSURE WILL KEEP THE AREA DRY THURSDAY. OVERRUNNING
MOISTURE FROM THE SOUTH WILL BRING A CHANCE FOR A WINTRY MIX TO THE
AREA THURSDAY NIGHT INTO FRIDAY MORNING. INITIAL PRECIPITATION WILL
FALL INTO DRY AIR AND COULD BEGIN AS A BRIEF PERIOD OF SNOW AND/OR
SLEET. FOR THE MOST PART...RAIN IS EXPECTED THURSDAY NIGHT.
EVAPORATIVE COOLING COULD BRING FREEZING RAIN TO THE BLUE RIDGE AND
TO LOCATIONS NORTH OF HIGHWAY 460 EARLY FRIDAY MORNING. FORECAST
SOUNDINGS CONTINUE TO CARRY A PROFILE FOR FREEZING RAIN...BUT THEY
ARE SLIGHTLY WARMER TODAY AND TIMING WINDOW IS SHORTER. AMOUNTS OF
RAIN/FREEZING RAIN ARE ALSO TRENDING LIGHTER AS GULF COAST
REFLECTION AND CONVECTION MAY ROB OUR MOISTURE. IN KEEPING THE
FORECAST SIMPLE...THURSDAY-FRIDAY FORECAST MAY SOUND WORSE THAN THE
EVENT ITSELF. BUT THEN AGAIN...ANY ICE...NO MATTER HOW LIGHT IS
STILL DANGEROUS.
ASIDE FROM THE P-TYPE ISSUE...MODELS ARE IN GOOD AGREEMENT WITH
PRECIPITATION COMING INTO THE REGION THURSDAY NIGHT AND FRIDAY. RAIN
FALLING INTO THE SURFACE RIDGE WILL ENHANCE IT TO BECOME AN INSITU
WEDGE FRIDAY AND FRIDAY NIGHT. WITH BULK OF THE RAIN TO OUR
SOUTH...FRIDAY COULD JUST BE A LIGHT RAIN/DRIZZLE...GRAY DAY WITH
TEMPERATURES STUCK IN THE 30S. OUTSIDE THE WEDGE...TOWARD
BLUEFIELD...TEMPERATURES COULD JUMP INTO THE LOWER 50S FRIDAY
AFTERNOON.
MEANWHILE...WHILE WE ARE WEDGED IN FRIDAY...A SURFACE REFLECTION
ACROSS THE GULF STATES WILL TRACK EAST OVER THE SOUTHEAST USA FRIDAY
NIGHT AND OFF THE CAROLINA COAST SATURDAY MORNING. THIS WAVE WILL
PUSH WARMER AIR INTO THE REGION AND WITH IT MORE RAIN. WITH THE
TRACK OF THIS REFLECTION ACROSS THE SOUTHEAST...THE BETTER CHANCE
FOR RAIN FRIDAY NIGHT AND SATURDAY MORNING WILL BE ALONG AND EAST OF
THE BLUE RIDGE AND INTO THE PIEDMONT. ONCE THIS WAVE MOVES EAST OF
THE REGION...HIGH PRESSURE IS EXPECTED TO MOVE OVER THE MID
ATLANTIC. THE ECMWF BRINGS ANOTHER WAVE ACROSS THE SOUTHEAST
SATURDAY NIGHT FOR ANOTHER CHANCE OF RAIN. SINCE THE 12Z ECMWF IS
TRENDING TOWARD THE GFS...WILL ONLY HAVE A SLIGHT CHANCE FOR RAIN
SATURDAY AFTERNOON/NIGHT.
FRIDAY LOOKS TO BE THE COLDEST DAY WITH MOST OF THE AREA STUCK IN AN
INSITU WEDGE. ONCE THIS WEDGE BREAKS...TEMPERATURES WILL WARM ABOVE
NORMAL NEXT WEEKEND.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 321 PM EST MONDAY...
THE 12Z ECMWF REMAINS CONSISTENT WITH PREVIOUS RUNS WITH OVERRUNNING
MOISTURE THURSDAY NIGHT...INSITU WEDGE FRIDAY INTO SATURDAY
AND...HIGH PRESSURE SUNDAY AND MONDAY. THE 12Z GFS IS CONSISTENT
THURSDAY NIGHT INTO FRIDAY NIGHT. SATURDAY AND SATURDAY NIGHT...THE
GFS CREATES A VERY COMPLICATED WEATHER PATTERN THAT WOULD BRING
MORE RAIN TO THE AREA. SINCE THIS IS A NEW SCENARIO...I HAVE LOW
POPS IN FOR SATURDAY BUT PRIMARILY WENT WITH THE ECMWF SOLUTION FOR
THIS FORECAST PACKAGE.
SURFACE HIGH PRESSURE WILL BE OVERRUN WITH WARM MOIST AIR THURSDAY
NIGHT INTO FRIDAY. RAIN FALLING OVERNIGHT WILL ENHANCE AN INSITU
WEDGE...KEEPING MOST OF THE AREA DAMP AND CHILLY INTO FRIDAY
POSSIBLY SATURDAY. THIS RAIN WILL ALSO BE FALLING INTO A VERY DRY
AIR MASS. EVAPORATIVE COOLING ALONG EASTERN SLOPES OF THE BLUE RIDGE
AND IN SOME MOUNTAIN VALLEYS SUCH AS THE GREENBRIER...NEW RIVER AND
SOUTHERN SHENANDOAH...COULD HAVE ICE FROM FREEZING RAIN EARLY FRIDAY
MORNING. FORECAST SOUNDINGS CONTINUE TO PROFILE FREEZING RAIN BUT
LIKE YESTERDAY...ARE A LITTLE WARMER AND THE DURATION IS LIMITED TO
4AM-10AM FRIDAY. CONVECTION ACROSS THE SOUTHEASTERN USA MAY ROB SOME
OF OUR MOISTURE...LIMITING ICE ACCRETIONS TO UNDER A TENTH OF AN
INCH ALONG THE BLUE RIDGE AND A GLAZING IN MOUNTAIN VALLEYS.
FRIDAY NIGHT INTO SATURDAY...THE GULF LOW SHOULD TRACK ALONG THE
SOUTHEAST USA...THEN OFF THE CAROLINA COAST. COOL DAMP CONDITIONS
COULD LINGER INTO SATURDAY BUT WARM ENOUGH TO KEEP PRECIPITATION AS
RAIN. THIS LOW MOVES OFF THE COAST SATURDAY NIGHT....BREAKING THE
WEDGE...IF IT IS STILL IN THE REGION. HIGH PRESSURE WILL THEN KEEP
THE REGION DRY UNTIL MONDAY NIGHT WHEN THE NEXT SYSTEM TRACKS TO THE
EAST COAST.
AREAS WITHIN THE WEDGE WILL HAVE A VERY SMALL DIURNAL CURVE IN
TEMPERATURES THURSDAY NIGHT INTO SATURDAY. TEMPERATURES COULD BE
STUCK IN THE 30S IN THE WEDGE WHILE MID 40S TO LOWER 50S ARE
POSSIBLE OUTSIDE THE WEDGE. TEMPERATURES ARE EXPECTED TO WARM ABOVE
NORMAL SUNDAY AND MONDAY.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
AS OF 1130 PM EST MONDAY...
VFR CONDITIONS WILL START TO DETERIORATE OVER THE WEST AFTER
MIDNIGHT WITH LOWERING CIGS SPREADING EAST TO THE BLUE RIDGE
DURING THE EARLY MORNING HOURS AND OUT EAST BY DAYBREAK. WINDS
ALOFT WILL ALSO BE ON THE INCREASE PROMPTING LLWS JUST OFF THE
DECK AT ALL LOCATIONS EXCEPT KBLF WHERE MIXING TO THE SURFACE WILL
PRECLUDE MENTION...BUT ALLOW FOR GUSTY SURFACE WINDS TO 30-35 KTS
AND PERHAPS EVEN STRONGER IMMEDIATELY AHEAD OF THE APPROACHING
PRECIP LATE. DEEPER MOISTURE SHOULD INCREASE QUICKLY AS THE FRONT
APPROACHES AND WILL SEE SOME PRECIP DEVELOP IN THE EARLY MORNING
HOURS FROM WEST TO EAST. PTYPE WILL BE A BIT PROBLEMATIC AS MODEL
SOUNDINGS INDICATE MOSTLY SNOW AT THE ONSET FOR KLWB... RAIN FOR
KDAN...AND A WINTRY MIX FOR SITES IN BETWEEN. APPEARS CIGS MAY
STAY VFR UNTIL ABOUT AN HOUR OR TWO BEFORE THE FAST MOVING AXIS OF
PRECIP ARRIVES...THEN QUICKLY LOWER INTO MVFR/OCNL IFR LEVELS WEST
OF THE BLUE RIDGE BEFORE DAWN...AND OUT EAST AROUND 12Z/7AM. LOOKS
LIKE MOST SPOTS WILL WARM ENOUGH TO CAUSE A CHANGE TO JUST -RA BY
MID MORNING EXCEPT VALLEYS WHERE TRAPPED COLD AIR COULD MAKE FOR
SOME LINGERING LIGHT MIX A WHILE LONGER. THIS BASED ON A SCENARIO
WHERE THE PRECIP IS AS MUCH AS 2 TO 3 HOURS FASTER THAN THE
FASTEST MODEL SOLUTION GIVEN TENDENCY OF THESE EVENTS TO ROCKET
EAST MUCH FASTER THAN PROGGED UNDER THE NOSE OF THE JET ALOFT.
VERY STRONG SOUTH/SW JET WILL REMAIN IN PLACE TUESDAY MORNING BUT
WILL BE LIMITED IN MIXING DOWN WITHIN PRECIP AS WILL SEE QUITE A
GRADIENT WITHIN THE LOWEST FEW THOUSAND FEET AS THE 85H 50-60 KT
JET SHIFTS EAST. THUS WILL KEEP LLWS MENTION IN AT MOST LOCATIONS
OUTSIDE OF KBLF UNTIL THINGS START TO MIX OUT BY LATE MORNING AND
ESPCLY DURING THE AFTERNOON WHEN TRAJECTORIES TURN MORE WESTERLY
AND STRONGER GUSTS OF 25-30+ KTS REACH THE SURFACE. OTRW THINK SIG
PRECIP WILL END BY 20Z/3PM MOST SPOTS WITH ONLY SOME LINGERING -RA
OR SHOWERS ACROSS THE NW INTO EARLY TUESDAY EVENING.
.EXTENDED AVIATION DISCUSSION...
GUSTY WINDS WILL CONTINUE BEHIND THE FRONT TUESDAY NIGHT INTO
WEDNESDAY...WITH ENOUGH SYNOPTIC MOISTURE LINGERING TO KEEP
CLOUDS AROUND FOR KLWB AND LIKELY KBLF AS WELL. HIGH PRESSURE WILL
THEN BUILD IN THURSDAY ALLOWING FOR VFR WEATHER. ANOTHER FRONTAL
SYSTEM WITH THE NEXT ROUND OF PRECIP WILL ARRIVE THURSDAY NIGHT
AND FRIDAY WITH MORE MVFR/IFR CONDITIONS POSSIBLE. THIS MAY BE
FOLLOWED BY ANOTHER IMPULSE HEADING NE FROM THE GULF COAST AREA
ALONG THE RESIDUAL FRONT ON SATURDAY WHICH MAY LINGER LOW FLYING
CONDITIONS INTO SATURDAY NIGHT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM 3 AM TO 10 AM EST TUESDAY FOR
VAZ007-009>020-022>024.
NC...WINTER WEATHER ADVISORY FROM 3 AM TO 10 AM EST TUESDAY FOR
NCZ001-002-018.
WV...WINTER WEATHER ADVISORY FROM 3 AM TO 10 AM EST TUESDAY FOR
WVZ042>045.
&&
$$
SYNOPSIS...WP
NEAR TERM...JH/WP
SHORT TERM...PC
LONG TERM...RCS
AVIATION...JH/MBS/RAB
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1126 PM CST MON FEB 18 2013
.SHORT TERM...TONIGHT
635 PM CST MON FEB 18 2013
A FEW ISSUES TO DEAL WITH AS DESCRIBED BELOW.
1. TEMPERATURES HAVE BEEN FALLING A LITTLE QUICKER THAN PREVIOUSLY
EXPECTED...WITH THE STRONG NORTHWEST WINDS DRIVING IN ARCTIC AIR
FASTER FROM THE DAKOTAS. ADJUSTED THE HOURLY TEMPERATURE TREND A
FEW TIMES TO ACCOUNT FOR THIS. SO FAR...LOW TEMPERATURES STILL
SEEM ON TRACK.
2. COMBINATION OF THE RECENT SNOW MELTING ON WARM ROADWAYS...ALONG
WITH THE ARCTIC AIR FLOWING IN AND SUN GOING DOWN ALLOWING ROADWAY
TEMPERATURES TO FALL BELOW FREEZING...HAS CAUSED ICY SPOTS TO
FORM. HAVE BEEN HANDLING THIS WITH SPECIAL WEATHER STATEMENTS.
3. RAP DERIVED WIND GUSTS SHOW VALUES OF 35-39 KTS BETWEEN 05-15Z
ACROSS MUCH OF THE FORECAST AREA...ABOUT 5 KNOTS STRONGER THAN
WHAT MOMENTUM TRANSFER WOULD SUGGEST ON RAP FORECAST SOUNDINGS. IF
THE DERIVED VALUES WERE CORRECT...WE NEED A WIND ADVISORY.
THE IDEA OF GUSTS INCREASING SEEM REASONABLE...AS DURING THE
AFOREMENTIONED TIME PERIOD WE ARE EXPERIENCING THE TROPOPAUSE DROP
OVER 100 MB...DUE TO THE UPPER TROUGH AXIS OVER WESTERN MINNESOTA
MOVING IN. IN ADDITION...DURING THIS TIME PERIOD IS WHEN THE REAL
ARCTIC AIR SURGE TAKES PLACE WITH 925MB TEMPS DROPPING NEARLY 10C.
HOWEVER...IN THE PAST THE RAP DERIVED WIND GUSTS HAVE HAD A LITTLE
HIGH BIAS. THUS...HAVE TAKEN A COMPROMISE APPROACH AND BROUGHT
WIND GUSTS UP A COUPLE KNOTS...STILL BELOW A WIND ADVISORY.
4. LATEST HRRR MODEL RUNS OF COMPOSITE REFLECTIVITY HAS SHOWN AN
ENHANCEMENT OF RETURNS DURING THE 06-12Z PERIOD ACROSS MUCH OF
WISCONSIN. RAP FORECAST SOUNDINGS DURING THE SAME TIME SHOW THAT
THE DEPTH OF THE CLOUD GROWS FROM ABOUT 4000 FT TO 8000 FT...AND
NEARLY ALL THE CLOUD IS IN THE DENDRITIC GROWTH ZONE. NOW THE LIFT
IS NOT ALL THAT IMPRESSIVE...BUT THERE IS WEAK LIFT THROUGHOUT
MUCH OF THE CLOUD DEPTH. IT APPEARS THE LIFT OCCURS WITH THE
TROPOPAUSE DROP ACCOMPANYING THE UPPER TROUGH AXIS...ALONG WITH
THE ASSOCIATED 500-300MB PV ADVECTION. GIVEN THE STEEP LOW LEVEL
LAPSE RATES IN PLACE AS WELL WITH THE COLD ADVECTION...FIGURE IT
WARRANTS RAISING PRECIPITATION CHANCES TO AT LEAST 60 ACROSS MUCH
OF WISCONSIN BETWEEN 06-12Z. STILL...THERE MAY ONLY BE A FEW
TENTHS OF HARD TO MEASURE SNOW DUE TO ALL THE WIND.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
314 PM CST MON FEB 18 2013
THE MAIN SNOW BAND WILL LIFT NORTH THROUGH THE REGION ON THURSDAY
NIGHT AS THE MAIN MID LEVEL TROUGH SWINGS NORTHWARD. THIS WILL
YIELD A BRIEF PERIOD OF MODERATE SNOW THAT WILL LIKELY BE
WEAKENING AS IT TRACKS TO THE NORTHEAST. QPF AMOUNTS APPEAR TO
RANGE FROM AROUND 0.35 INCHES IN NORTHEAST IOWA TO AROUND 0.15
INCHES IN NORTH CENTRAL WISCONSIN BY THE TIME THE SYSTEM ENDS ON
FRIDAY. WITH SNOW RATIOS EXPECTED TO BE IN THE 10/15:1 RANGE...IT
LOOKS LIKE THE HIGHEST SNOW ACCUMULATIONS SHOULD BE ACROSS
NORTHEAST IOWA AND PORTIONS OF SOUTHEAST MINNESOTA AND FAR
SOUTHWEST WISCONSIN WHERE 3-5 INCHES COULD FALL. SNOW AMOUNTS ARE
EXPECTED TO DECREASE TO THE NORTHEAST WITH A 2-4 INCH RANGE
EXPECTED INTO NORTH CENTRAL WISCONSIN.
LIGHT SNOW WILL COME TO AN END FROM SOUTH TO NORTH FRIDAY NIGHT
INTO SATURDAY WITH A BRIEF RIDGE OF HIGH PRESSURE EXPECTED TO MOVE
ACROSS THE REGION NEXT WEEKEND. ANOTHER SYSTEM IS THEN FORECAST TO
OCCUR SOMETIME BETWEEN SUNDAY AND TUESDAY WITH THE 19.12Z
GFS/ECMWF/FIM MODELS ARE SHOWING DIFFERENT TIMING IN REGARD TO
WHEN THE LOW PASSES THROUGH. THE 19.12Z GFS IS THE FASTEST WITH
HAVING THE LOW COME THROUGH ON SUNDAY WHILE THE 19.12Z ECMWF IS
THE SLOWEST WITH HAVING IT COME THROUGH ON MONDAY. THE 19.12Z FIM
SEEMS TO BE A BLEND IN BETWEEN THE TWO AND MAY BE A GOOD
COMPROMISE. THE TRACK THOUGH SEEMS TO BE SIMILAR WITH TAKING THE
CENTER OF THIS LOW OFF TO THE WEST OF THE REGION...WHICH PROBABLY
LEAVES US MORE INTO A MIXED P-TYPE.
&&
.AVIATION...THROUGH 06Z WEDNESDAY
1126 PM CST MON FEB 18 2013
CYCLONIC FLOW OF MOISTURE AROUND DEEPENING LOW PRESSURE LIFTING
FROM LAKE MICHIGAN INTO EASTERN ONTARIO WILL MAINTAIN AN MVFR
STRATUS DECK AT BOTH TAF SITES THROUGH 06Z WEDNESDAY. AS WE
APPROACH 06Z...THOUGH...DRIER AIR COMING OUT OF ARCTIC HIGH
PRESSURE DROPPING DOWN INTO MINNESOTA MAY BEGIN TO CLEAR THE
CLOUDS OUT. THE COMBINATION OF THE MVFR STRATUS DECK SITUATED
MOSTLY IN THE DENDRITIC GROWTH ZONE...ALONG WITH SERIES OF TROUGHS
MOVING THROUGH DURING THE MORNING HOURS TO PROVIDE LIFT...WILL
RESULT IN PERIODS OF IFR TO VFR SNOW/SNOW SHOWERS. THE LOWEST
VISIBILITIES ARE EXPECTED PRIOR TO 12Z WHEN THE STRONGEST TROUGH
MOVES THROUGH...WHICH HAS ALREADY PRODUCED IFR VISIBILITIES AT
KRST. LOOK FOR THE FLURRIES TO COME TO END FOR THE AFTERNOON AS
THE DEPTH OF THE CLOUD DECREASES.
ALONG WITH THE SNOW AND STRATUS...WINDS ARE GOING TO BE AN ISSUE
TOO. NORTHWEST WINDS AT BOTH TAF SITES SHOULD HOLD STEADY BETWEEN
15 AND 20 KT WITH GUSTS OF 25 AND 30 KT THROUGH THE DAY
TODAY...AIDED BY COLD AIR FLOWING IN...A TIGHT PRESSURE GRADIENT
AND DAYTIME MIXING. EXPECT THE GUSTS TO DIMINISH AND WINDS TO
DECREASE SLIGHTLY BY LATE TUESDAY EVENING WITH THE PRESSURE
GRADIENT BEGINNING TO RELAX.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
314 PM CST MON FEB 18 2013
WI...NONE.
MN...WIND CHILL ADVISORY FROM 3 AM TO NOON CST TUESDAY FOR MNZ086-087-
094-095.
IA...WIND CHILL ADVISORY FROM 3 AM TO NOON CST TUESDAY FOR IAZ008-009-
018-019.
&&
$$
SHORT TERM...AJ
LONG TERM...HALBACH
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1016 PM CST MON FEB 18 2013
.UPDATE...CYCLOGENESIS EXPECTED TO INTENSIFY FROM NOW THROUGH 12Z
TUE WITH A 987 MB LOW EXPECTED OVER FAR ERN UPPER MI AT THAT TIME.
DRY SLOT IS ENDING THE SNOW FROM WEST TO EAST WITH SOME
DISSIPATION FROM THE SOUTH AS WELL. THIS WILL LIMIT SNOW ACCUMS
OVER FAR SE WI. HOWEVER...UPPER TROUGH TO THE EAST WILL AMPLIFY
VIA CYCLOGENESIS AND BECOME A CLOSED UPPER LOW OVER WI LATER TNT.
THUS SNOW WILL REDEVELOP FROM THE NORTH AND WEST AS SHOWN BY RADAR
TRENDS FROM SRN MN INTO CENTRAL WI. EXPECT SOME ADDITIONAL...MINOR
SNOW ACCUM LATER TNT INTO TUE AM. FALLING TEMPS AND WINDY
CONDITIONS LOOK ON TRACK FOR THE OVERNIGHT AND TUE AM WITH VERY
COLD TEMPS AND WIND CHILLS EXPECTED. WINDS WILL APPROACH WIND
ADVISORY CRITERIA FOR TUE ESPECIALLY OVER EAST CENTRAL WI.
&&
.AVIATION/06Z TAFS/...PERIODS OF LIGHT SNOW WILL CONTINUE THROUGH
TUE AM AND DIMINISH BY TUE AFTERNOON. VSBYS WILL RANGE FROM 1-3
MILES IN SE WI THROUGH 07Z AND THEN RANGE FROM 3-6 MILES THE
REMAINDER OF THE NIGHT AND THROUGH TUE AM OVER ALL OF SRN WI. IFR
CIGS WILL TRANSITION TO MVFR CIGS THROUGHOUT TUE AM AS MUCH
COLDER AIR ON BRISK WEST TO NORTHWEST WINDS ARRIVES. MVFR CIGS
WILL BECOME SCT CLOUD COVER TUE EVENING AS DRY ARCTIC AIR
CONTINUES TO MOVE INTO THE REGION.
&&
.PREV DISCUSSION... /ISSUED 237 PM CST MON FEB 18 2013/
SHORT TERM...
TONIGHT - CONFIDENCE...MEDIUM
STRONG COLD FRONT EXITS TO THE EAST OF WI THIS EVENING. HRRR MODEL
HAS GOOD HANDLE ON PRECIP TRENDS AND FOLLOWED ON POP GRIDS.
WEST/EAST TREND IN CHANGEOVER OF PRECIP TYPE AS COLDER TEMPS DRIVE
IN. UPPER TROUGH AXIS SHIFTS EAST FROM THE PLAINS. QUICK HITTING DEF
ZONE BAND OF PRECIP HAS SOME PUNCH TO IT BACK IN CNTRL/ERN IA. DECENT
UPPER JET DIVERGENCE WITH THE NEWD MOVG UPPER WAVE FROM SRN IA WILL
KEEP PRECIP GOING WELL INTO THE EVENING WITH POTENTIAL FOR LIGHT
SNOW ACCUMS...MOSTLY 0.5 - 1.0...THOUGH BULK OF PRECIP EXPECTED WHEN
LIQUID SUPPORTING PROFILE IN PLACE. SEEING SOME MINUS TEENS AT 925
IN WESTERN CWA LATER TONIGHT WITH GUSTY NW WINDS AFTER FROPA.
TUESDAY - CONFIDENCE...MEDIUM
CONTINUED COLD AIR ADVECTION IN WAKE OF THE LOW. GUSTY NW WINDS
COMBINED WITH THE MUCH COLDER AIRMASS WILL MAKE FOR SOME RATHER
CHILLY WIND CHILLS...ESPECIALLY EARLY. 925 TEMPS -15 TO -19C ALL
DAY. HIGHS WILL NOT MAKE IT OUT OF THE TEENS. WILL GET GUSTS INTO
THE 30-40 MPH RANGE GIVEN DECENT GRADIENT/MIXED ENVIRONMENT TAPPING
INTO SOME OF THE STRONGER WINDS AT 900-925 MILLIBARS. WILL KEEP SOME
CHANCE POPS IN THE EASTERN CWA AS CYCLONIC FLOW KEEPS SHSN POTENTIAL
IN PLACE. WENT WITH A BLEND OF ECMWF/NAM QPF AS GFS LOOKS TOO
GENEROUS WITH QPF.
TUESDAY NIGHT AND WEDNESDAY...FORECAST CONFIDENCE...HIGH
THE MID/UPPER LEVEL TROUGH OVER THE EASTERN GREAT LAKES AND
SOUTHEAST CANADA MOVES OFF AS AN UPPER LEVEL RIDGE MOVES INTO THE
UPPER MISSISSIPPI VALLEY WEDNESDAY. STILL A COLD CYCLONIC FLOW AT
700 MB TUESDAY NIGHT AND WEDNESDAY. THE BRISK NORTHWEST WINDS
TUESDAY NIGHT DIMINISH AS SURFACE HIGH PRESSURE REACHES WISCONSIN
WEDNESDAY AFTERNOON.
THURSDAY AND FRIDAY...FORECAST CONFIDENCE...MEDIUM
THE STRONG SHORTWAVE EXITS THE SOUTHERN ROCKIES AND REACHES THE
WESTERN KANSAS REGION THURSDAY MORNING. THE 12Z GFS/GEM/NAM TAKE
THE UPPER LOW INTO EASTERN NEBRASKA/WESTERN IOWA AREA EARLY THURSDAY
EVENING...AS IT SLOWLY FILLS/WEAKENS. THE UPPER LOW REMAINS IN THE
DAKOTA/WESTERN MINNESOTA BORDER AREA LATE THURSDAY NIGHT AND FRIDAY...
ALONG WITH THE SLOW WEAKENING TREND.
THE NAM SHOWS UPPER LEVEL DIVERGENCE SPREADING ACROSS SOUTHERN
WISCONSIN THURSDAY. THE RATHER STRONG 700 UPWARD MOTION OVER IOWA
REACHES NORTHERN ILLINOIS...EASTERN IOWA AND SOUTHEAST MINNESOTA
THURSDAY AFTERNOON...BUT REMAINS WEAK OVER SOUTH CENTRAL AND
SOUTHEAST WISCONSIN INTO THE EARLY EVENING. THE HIGH 700 MB RH
ENTERS AREAS SOUTHWEST OF MADISON BY 6 PM. THE NAM FORECAST
SOUNDINGS SHOW VERY DRY AIR BELOW 10 THSD FT. HOWEVER THE RATHER
STRONG UPWARD MOTION TOWARDS DUBUQUE DOES SATURATE THE AIR MASS IN
THE FAR SOUTHWEST TOWARD EVENING. THE 12Z GFS IS SOMEWHAT FASTER
BRINGING 700 MB SATURATION FROM NEAR LONE ROCK TO
JANESVILLE...ALTHOUGH THE 850 MB SATURATION IS STILL OVER FAR
SOUTHWEST WISCONSIN. THEREFORE MUCH OF THE FORECAST AREA MAY
REMAIN DRY.
NEXT PROBLEM IS THAT THE STRONGEST 700 MB UPWARD MOTION IS IN A
FAIRLY NARROW BAND THAT PUSHES QUICKLY NORTHEAST THURSDAY NIGHT AS
THE 850 LOW LEVEL JET WEAKENS.
THE 12Z GFS GIVES 24 HOUR PRECIPITATION VALUES ONLY AROUND 0.20 INCH.
THE 00Z ECMWF IS SIMILAR WHILE THE 12Z GEM IS A JUST A LITTLE
HIGHER. SNOW RATIOS AVERAGE BETWEEN 10 AND 15 TO 1. THIS WOULD
INDICATE AROUND A 2 TO POSSIBLY 3 INCH SNOW TOTAL. EVENT CONSENSUS
PRECIPITATION IS AROUND 0.30.
LONG TERM...
+
SATURDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
THE MID LEVEL TROUGH CONTINUES TO SHEAR OUT FROM WEST TO EAST AND
LIFT TOWARD THE UPPER GREAT LAKES AS THE MID LEVEL AND SURFACE
TROUGH LIFTS INTO NORTHERN WISCONSIN BY EARLY SATURDAY MORNING.
THEREFORE MAINLY LIGHT SNOW OR FLURRIES ARE EXPECTED ACROSS THE
SOUTH FRIDAY NIGHT.
SUNDAY AND MONDAY...FORECAST CONFIDENCE...LOW TO MEDIUM
THE MODELS BEGIN A SOUTHWEST MID/UPPER FLOW AHEAD OF ANOTHER
TROUGH OVER THE SOUTHERN/CENTRAL ROCKIES ON THE 00Z ECMWF BUT
FARTHER NORTH ON THE 12Z GFS. THIS SHORTWAVE REACHES THE NORTHERN
AND CENTRAL PLAINS SUNDAY ON THE GFS...BUT REMAINS OVER THE
ROCKIES AS IT DIGS SOUTH ON THE 00Z ECMWF.
BY MONDAY THIS SHORTWAVE PUSHES THROUGH WISCONSIN ON THE 12Z GFS
BUT ONLY REACHES THE EASTERN KANSAS/WESTERN MISSOURI AREA MONDAY.
A WEAK SURFACE LOW REACHES THE WESTERN LAKE SUPERIOR AREA MONDAY
MORNING...WHILE A STRONG LOW REMAINS OVER OKLAHOMA ON THE 00Z
ECMWF. GIVEN THE LARGE DISCREPANCY CONFIDENCE IS LOW...BUT WOULD
TREND TOWARD THE 00Z ECMWF BASED ON BOTH MODELS PRIOR MODEL RUNS.
AVIATION/00Z TAFS/...
MID/HIGH LEVEL CLOUDS TO GIVE WAY TO MORE
WIDESPREAD MVFR CEILINGS AS MOISTURE INCREASES AND CEILINGS LOWER
WITH ARRIVAL OF PRECIP. EXPECTING PRECIP TO OVERSPREAD THE AREA
BETWEEN 21-00Z TIME FRAME AS RAIN. WINDOW OF IFR CEILINGS THIS
EVENING IN THE STEADY PRECIP AREAS. AS COLD FRONT MOVES IN LATER
THIS AFTERNOON/EVENING...THE TRANSITION TO LIGHT SNOW WILL SPREAD
WEST TO EAST. QUITE BLUSTERY TUESDAY WITH GUSTY NW WINDS AND SHSN
POTENTIAL INTO AT LEAST MIDDAY. MVFR CEILINGS WILL PERSIST IN THE
CYCLONIC FLOW.
MARINE...
A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH 6 AM TUESDAY
WITH A GALE WARNING GOING INTO EFFECT FROM 6AM TUE THROUGH 6 PM
TUESDAY. A SMALL CRAFT ADVISORY WILL THEN BE NEEDED AT THAT POINT
THROUGH WEDNESDAY MORNING. THESE CONDITIONS ARE DUE TO THE
APPROACH...THEN PASSAGE OF A STRONG LOW PRESSURE SYSTEM AND COLD
FRONT TODAY AND THIS EVENING. STRONG SOUTH WINDS WILL PRECEDE THE
LOW...FOLLOWED BY WINDS VEERING TO THE WEST BEHIND THE FRONT AND
INCREASING TO GALE FORCE BY TUESDAY MORNING.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR LMZ643>646.
GALE WARNING UNTIL 6 PM CST TUESDAY FOR LMZ643>646.
&&
$$
UPDATE...GEHRING
TONIGHT/TUESDAY AND AVIATION/MARINE...COLLAR
TUESDAY NIGHT THROUGH MONDAY...HENTZ
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
923 AM EST TUE FEB 19 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK FROM THE GREAT LAKES REGION TODAY, THEN
ACROSS SOUTHEASTERN CANADA TO NORTHERN NEW ENGLAND TONIGHT AND
WEDNESDAY. AN ASSOCIATED COLD FRONT WILL SLIDE ACROSS OUR AREA
THIS EVENING. HIGH PRESSURE FROM CENTRAL CANADA WILL THEN BUILD
SOUTH AND EASTWARD THURSDAY. THIS HIGH WILL BE SHIFTING EAST LATE
THURSDAY INTO FRIDAY, AS ANOTHER LOW PRESSURE SYSTEM MOVES INTO THE
GREAT LAKES AND OHIO VALLEY FRIDAY NIGHT INTO SATURDAY. LOW PRESSURE
FARTHER SOUTH ON THE COLD FRONT THEN EXITS THE MID ATLANTIC COAST
SATURDAY NIGHT INTO SUNDAY. HIGH PRESSURE THEN ARRIVES LATE SUNDAY
INTO MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BASED ON LATEST RADAR TRENDS, HAVE SLOWED DOWN THE ONSET OF PRECIP
TODAY AS IT IS HAVING A HARD TIME PROGRESSING EWD THIS MORNING.
THIS LATER ARRIVAL SHOULD FURTHER MITIGATE ANY WINTRY PRECIP CHCS
EXCEPT FOR THE FAR N AND W. LLJ KICKED IN AND HAS ALREADY WARMED
SOME LOCATIONS QUITE NICELY. KRDG WENT FROM 27 DEGREES TO 40
DEGREES IN ONE HOUR, YET OTHER LOCATIONS STILL REMAIN BELOW
FREEZING. SO, FOR THIS UPDATE, HAVE LOWERED POPS FOR THE NEXT FEW
HOURS ACRS THE BOARD, AND TRIED TO CAPTURE PTYPE TRENDS AS BEST AS
PSBL, REALIZING THE LARGE SWINGS IN TEMPS WILL BE DIFFICULT TO
FCST IN SOME LOCATIONS. ALSO TWEAKED BACK WINDS IN SOME AREAS FOR
THE NEXT FEW HOURS BASED ON CURRENT TRENDS.
THE GFS INITIALIZATION LOOKED SLIGHTLY BETTER THAN THE WRF-NMMB AND
THE FORECAST PACKAGE WAS LEANED ABOUT THREE QUARTERS TOWARD ITS
TIMING. WE DID OPT FOR THE WRF-NMMB SFC THERMAL FIELDS OVER THE GFS
IN THE POCONOS.
THE OVERALL FORCING STILL LOOKS SPLIT. THE FCST ISENTROPIC LIFT IS
NOT ROBUST, THE MID LEVEL QVEC CONVERGENCE AND FGEN FORCING WEAKEN
AS IT MOVES ACROSS THE APPALACHIANS. THE LOW LEVEL THETA E RIDGE IS
NOT ANYTHING TO WRITE HOME FOR (PLENTY OF LOW SFC DEW POINTS INTO
GEORGIA). THE BEST "CONVECTIVE" CONTRIBUTION GOES NORTHWEST OF CWA.
WHAT IT STILL DOES HAVE GOING FOR IT IS THE EXIT REGION OF THE 250MB
JET. WE SAW WHAT THAT DID FOR THE SYSTEM LAST FRIDAY NIGHT AND WE
ARE COUNTING ON IT TO SAVE THE QPF DAY.
SENSIBLE WEATHER, WE START BRINGING IN THE POPS AT 14Z, CLOSER TO
THE GFS TIMING. THERE IS PLENTY OF DRY AIR FOR THIS MOISTURE TO
OVERCOME, SO WE BELIEVE IT WILL TAKE A COUPLE OF HOURS FOR PCPN TO
GET GOING (EARLY TO MID AFTERNOON). THIS ALSO COINCIDES BETTER WITH
THE JET. THE THETA E RIDGE GETS OFFSHORE PRETTY FAST AND THE FCST
MID LVL WAA IS WAY EAST BY 00Z, SO POPS WERE DROPPED LATE IN THE
AFTERNOON IN THE WEST.
FOR PTYPE, THE DRY AIR MASS IN PLACE WILL MAKE IT EASY TO EVAPORATE
COOL TO SNOW. THE QUESTION IS HOW DEEP WILL THE THERMAL SOUNDING
HAVE TO BE COOLED FOR SNOW. THE LATEST ACAR SOUNDING FROM PHL
ALREADY HAS THE FREEZING LEVEL ABOVE 6K. SO THE "MENTION" OF SNOW
WAS LIMITED TO THE PHL FAR NWRN SUBURBS, RARITAN BASIN IN NJ AND
POINTS NW. THE LATER ARRIVAL TIME AND LIKELY LIGHT INTENSITY
START HAS PRETTY MUCH REMOVED THE RISK FOR FREEZING RAIN.
THE ONLY LOCALE THAT SHOULD HANG ON TO SNOW ARE THE POCONOS WHERE
THE WRF/HI RES ARW/ AND HRRR ALL DROP SFC TEMPS TO FREEZING AND
LEVEL THEM THERE. LATE IN THE DAY SOME SOUNDINGS SUGGEST WE LOSE THE
ICE AND WITH LESSER INTENSITY AND A CONTINUING SOUTH WIND, THE SNOW
COULD MIX OR CHANGE TO RAIN EVEN THERE. AS MENTIONED ABOVE THE MID
LEVEL FGEN FORCING WEAKENS AND THE BEST FGEN FRCG THAT MAKES IT
ACROSS THE MOUNTAINS REMAINS TOWARD THE 500MB LEVEL, COMES AS NO
SURPRISE THAT THE BEST OMEGA IS FCST TO ABOVE THE SNOW GROWTH AREA.
THIS COMBINED WITH MODEL QPFS OF AROUND A QUARTER OF AN INCH SUGGEST
AN INCH OR TWO OF SNOW AS THE MOST LIKELY OUTCOME FOR THE HIGHER
TERRAIN IN THE POCONOS, SO NO ADVISORY WILL BE ISSUED AT THIS TIME.
OUR BIGGEST UNCERTAINTY REMAINS WITH THE WIND AND TO A CERTAIN
DEGREE ITS TIED TO THE TEMPERATURES. THE FORECAST SOUNDINGS REMAIN
VERY BULLISH ON DEEP MIXING AND ALBEIT TAKING THE HIGHER LEVEL OF
THE TWO BUFKIT MOMENTUM TRANSPORT WINDS GIVE US ADVISORY LEVEL WIND
GUSTS. OF LATE THE SFC GUSTS HAVE BEEN BETTER REPRESENTED BY THE
LOWER TRANSPORT GUST WHICH SUGGEST INTO THE 30S FOR GUSTS. THERE MAY
BE A WINDOW OF OPPORTUNITY FOR MORE ROBUST GUSTS THAN WE ARE
FORECASTING BEFORE THE SHOWERS ARRIVE AND MAKE THE SOUNDING MORE
ISOTHERMAL. THIS WILL DEPEND ON TEMPERATURES JUMPING THIS MORNING
BEFORE THE SHOWERS ARRIVE AND GETTING HIGHER THAN WE ARE CURRENTLY
ANTICIPATING. WHETHER ITS THE CHILLY BAYS OR OCEAN OR SKY COVER, MOS
GUIDANCE REMAINS PRETTY CONSERVATIVE WITH MAX TEMPS (AND WITH THE
WINDS TOO). WE STAYED CLOSE TO THEM NORTHWEST OF I95, BUT WERE MORE
BULLISH THAN BOTH SOUTHEAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
THE COLD FRONT SHOULD CLEAR OUR CWA EARLY THIS EVENING AND ANOTHER
COLD AIR MASS WILL START WORKING ITS WAY INTO OUR CWA. ANY POPS AWAY
FROM THE HIGHER TERRAIN WERE IN JUST EARLY IN THE EVENING. THERE
ARE MODEL DIFFERENCES AS TO HOW QUICKLY THE LAKE EFFECT MACHINE GETS
GOING. EVEN WITHOUT IT, THERE ARE ENOUGH SHORT WAVES MOVING THROUGH
TO LIKELY TRIGGER SOME SNOW SHOWERS NORTHWEST AND WE KEPT POPS GOING.
LIKE TODAY, WE THINK STAT GUIDANCE MAY BE A BIT TOO WEAK WITH THE
WINDS. GIVEN THE STRONG CAA, WE WENT HIGHER. IN TANDEM WE WERE ALSO
LOWER THAN STAT GUIDANCE WITH THE MIN TEMPS.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE SYNOPTIC SETUP IS AN ACTIVE ONE AND IS INITIALLY COMPRISED OF A
STRONG UPPER-LEVEL TROUGH IN THE NORTHEAST WITH ANOTHER ONE DIGGING
ACROSS THE INTERMOUNTAIN WEST. THE FIRST ONE EXITS THROUGH THURSDAY,
THEN THE BROADENING OF THE TROUGH IN THE WEST HAS SOME ENERGY THAT
EJECTS INTO THE PLAINS AND OHIO VALLEY. THIS SYSTEM MAY BECOME
STRETCHED OUT AS IT WEAKENS DUE TO THE MAIN TROUGH DAMPENING OUT
WHILE IT RELOADS ONCE AGAIN IN THE WEST. THE SOUTHERN JET LOOKS TO
REMAIN ACTIVE, THEREFORE ENERGY TRAVERSING THIS CORRIDOR WILL TEND
TO SLIDE OFF THE MID ATLANTIC COAST. WE MAY SEE THE SYSTEM ORGANIZE
MORE AS IT EXITS OFF THE MID ATLANTIC COAST DURING THE WEEKEND AS
SHORT WAVE ENERGY SHARPENS A BIT AND INCREASING BAROCLINIC EFFECTS
OCCUR. YET ANOTHER LARGE STORM LOOKS TO EJECT INTO THE PLAINS EARLY
NEXT WEEK WITH ITS COLD FRONT /OR EVEN OCCLUDED FRONT/ APPROACHING
FROM THE WEST MONDAY NIGHT. WE USED A MODEL BLEND FOR WEDNESDAY INTO
FRIDAY, THEN USED HPC GUIDANCE AND CONTINUITY THEREAFTER.
FOR WEDNESDAY AND THURSDAY...AN UPPER-LEVEL TROUGH IS FORECAST TO
DOMINATE THE NORTHEAST AS LOW PRESSURE TRACKS ACROSS SOUTHEASTERN
CANADA AND NEW ENGLAND, THEN EVENTUALLY TO THE CANADIAN MARITIMES.
THERE IS DECENT 850 MB CAA FORECAST WEDNESDAY BEFORE IT BACKS OFF
WEDNESDAY NIGHT AND THURSDAY. THE COMBINATION OF THE CAA AND A TIGHT
PRESSURE GRADIENT LEADS TO BLUSTERY CONDITIONS. THIS LOOKS SIMILAR
TO THIS PAST SUNDAY, HOWEVER THE MID LEVEL COLD CORE IS FORECAST TO
NOT BE QUITE AS COLD COMPARED TO SUNDAY. DESPITE THIS, VERTICAL
MIXING WILL DEEPEN WEDNESDAY AND THE FORECAST SOUNDINGS SHOW GUSTS
TO NEAR 35 KNOTS ARE CERTAINLY POSSIBLE. THE FLOW AT 925 MB IS
FORECAST TO BE MAINLY IN THE 30-35 KNOT RANGE WITH SOME HIGHER WINDS
AT 850 MB. IF WE ARE ABLE TO MIX EVEN DEEPER, THEN SOME NEAR ADVISORY
LEVEL GUSTS /40 KNOTS/ WILL BE POSSIBLE. WE WOULD LIKE TO SEE
WINDS CLOSER TO 50 KNOTS AT 850 MB FOR ADVISORY LEVEL WINDS,
THEREFORE WE WILL CONTINUE WITH GUSTS UNDER CRITERIA HOWEVER IT
WILL STILL BE A BLUSTERY/WINDY DAY.
THE GUSTY WINDS SHOULD CONTINUE WEDNESDAY NIGHT DESPITE WHEN WE
TYPICALLY SEE THEM DECOUPLE. THE PRESENT OF ENOUGH OF A MIXED LAYER
WILL KEEP AT LEAST SOME WIND GOING THROUGH THE NIGHT. THE AIRMASS
STARTS TO MODIFY DURING THURSDAY HOWEVER THE WESTERN EDGE OF THE MID
LEVEL COLD CORE IS NEARBY AND THIS WILL STILL COMBINE WITH A
LINGERING TIGHTENED PRESSURE GRADIENT TO RESULT IN BRISK CONDITIONS.
THESE WINDS WILL EASE UP AND BECOME NORTHERLY LATER THURSDAY AS HIGH
PRESSURE BUILDS DOWN FROM NEAR THE GREAT LAKES.
THE CAA ALONG WITH A NORTHWEST FLOW WILL PRODUCE LAKE EFFECT SNOW
DOWNWIND OF LAKES ERIE AND ONTARIO. THIS FLOW LOOKS CONDUCIVE TO
CARRY SOME STREAMERS INTO NORTHEASTERN PENNSYLVANIA, THEREFORE WE
WILL CARRY HIGHER CHC POPS INTO THE POCONOS FOR AT LEAST SCATTERED
SNOW SHOWERS. THIS SHOULD EASE UP ESPECIALLY THURSDAY AS THE AIRMASS
STARTS TO MODIFY AND THE FLOW MAY TURN MORE NORTHERLY.
FOR FRIDAY AND SATURDAY...THERE IS GENERALLY LOWER CONFIDENCE DURING
THIS TIME FRAME AS OUR SENSIBLE WEATHER IS FROM ENERGY THAT BECOMES
STRETCHED OUT FROM THE MIDWEST TO THE OHIO VALLEY AND SOUTHWARD.
HIGH PRESSURE CENTERED ACROSS SOUTHEASTERN CANADA LOOKS TO BE WEDGED
DOWN INTO THE MID ATLANTIC FOR A TIME FRIDAY. THIS MAY RESULT IN
SOME COLDER LOW-LEVEL AIR REMAINING WHILE WARMING TAKES PLACE ALOFT.
THE PRECIPITATION SHIELD WITH THIS INCOMING SYSTEM MAY END UP
SPLITTING, WITH THE MORE ORGANIZED AREA TO OUR SOUTH. WHILE WE HAVE
WAA, THE ISENTROPIC UPGLIDE AND ASSOCIATED LARGE SCALE ASCENT LOOKS
WEAKER OVER OUR AREA. THIS COULD JUST RESULT IN SOME LIGHT
PRECIPITATION. THERE LOOKS TO BE ENOUGH DRY AIR IN PLACE AHEAD OF
THIS FEATURE, WHERE THE PRECIPITATION DOES NOT START UNTIL LATER IN
THE DAY FRIDAY.
THERE DOES LOOK TO BE ENOUGH ENERGY IN THE SOUTHWEST FLOW ALOFT TO
ORGANIZE A SURFACE LOW, WHICH THEN TRACKS TO OUR SOUTH SATURDAY.
THIS COULD KEEP MORE OF AN EASTERLY WIND ACROSS OUR AREA ALONG WITH
COOLER TEMPERATURES. AT THIS JUNCTURE, PRECIPITATION LOOKS TO BE ON
THE LIGHT TO MODERATE SIDE UNLESS THE SYSTEM TRACKING OFF THE MID
ATLANTIC COAST CAN STRENGTHEN SOME MORE WHICH RESULTS IN STRONGER
LIFT SPREADING NORTHWARD. THE ECMWF IS INDICATING THIS POTENTIAL BUT
ALSO MAINTAINS THE PROGRESSIVE LOOK AS WELL. GIVEN MORE UNCERTAINTY
IN THE QPF AMOUNTS AND THERMAL FIELDS, WE DID NOT CHANGE MUCH FROM
CONTINUITY. OVERALL, MAINLY SOME RAIN ACROSS THE SOUTHERN AREAS WITH
THE CHC FOR A WINTRY MIX AT TIMES FARTHER NORTH.
FOR SUNDAY...LOW PRESSURE SHOULD BE EXITING THE MID ATLANTIC COAST
DURING THE MORNING AS A SHORT WAVE TROUGH AMPLIFIES SOME. THERE IS
SOME GUIDANCE THAT SUGGESTS THE SYSTEM IS SLOWER/A BIT STRONGER AND
THEREFORE INTRODUCES MORE PRECIPITATION FOR SUNDAY. AS OF NOW, WE
FOLLOWED HPC`S LEAD AND KEPT THE CONSOLIDATED SURFACE LOW EXITING TO
OUR EAST SUNDAY MORNING. THIS WOULD MEAN PERHAPS SOME PRECIPITATION
TO START, THE HIGH PRESSURE BEGINS TO BUILD IN. THE OVERALL
UPPER-LEVEL TROUGH DOES NOT LOOK TO AMPLIFY MUCH OVER OUR AREA
DURING THIS TIME FRAME, THUS THE FLOW BEING PROGRESSIVE. SOME COOLER
AIR LOOKS TO TRY AND SETTLE SOUTHWARD AS THE SURFACE LOW EXITS,
THEREFORE PERHAPS SOME MIXED PRECIPITATION OR SNOW BEFORE IT ENDS
ACROSS THE NORTH ESPECIALLY. WE DID NOT MAKE TO MANY CHANGES DUE TO
LOWER CONFIDENCE IN THE DETAILS.
FOR MONDAY...THE ACTIVE PATTERN CONTINUES AND THIS FEATURES
AN AMPLIFYING UPPER-LEVEL TROUGH MOVING EASTWARD. THIS WILL DRIVE
LOW PRESSURE ACROSS THE PLAINS MONDAY. THIS SYSTEM LOOKS TO
OCCLUDE WITH ANOTHER SURFACE LOW DEVELOPING FARTHER SOUTH ALONG THE
TRIPLE POINT. THERE IS A DECENT RIDGE BUILDING DOWNSTREAM OF THE
TROUGH, AND THIS WOULD HELP TO PULL MORE MOISTURE NORTHWARD AHEAD OF
THE FRONTAL BOUNDARY. THE LARGE SCALE LIFT LOOKS STRONGER WITH THIS
SYSTEM, AND IT COULD BE ENHANCED SOME AS THE SOUTHERN SURFACE LOW
TRACKS NORTHEASTWARD. WE WENT WITH A DRY MONDAY AS MID LEVEL RIDGING
ARRIVES, ALTHOUGH CLOUDS WILL INCREASE MAINLY LATE.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
HAVE SLOWED DOWN ONSET OF PRECIP BASED ON CURRENT RADAR TRENDS AND
TWEAKED WINDS DOWN A BIT FOR THE NEXT FEW HOURS, BUT OVERALL FCST
REMAINS ON TRACK.
DURING THE SECOND HALF OF THE MORNING WE ARE FORECASTING SHOWERS
TO SPREAD ACROSS THE REST OF THE TERMINALS AND REACHING ACY BY
18Z. CONDITIONS WHEN SHOWERS FIRST ARRIVE ARE VFR TO OUR WEST. THE
FORECAST SOUNDINGS ARE SHOWING CONSIDERABLE GUSTINESS. WE WENT
WITH THE MORE CONSERVATIVE SUGGESTION. CONFIDENCE IS LOWER THAN
AVERAGE ABOUT THE WIND GUSTS. UNIDIRECTIONAL SOUTH WINDS, SO ONCE
THE GUSTINESS STARTS, THE LLWS SHOULD END.
DURING THE AFTERNOON WE BROUGHT THE TERMINALS DOWN INTO MVFR AS
THE MORE WIDESPREAD AND HEAVIER SHOWERS MOVE ACROSS THE REGION. AS
THE SHOWERS MOVE IN, THE GUSTINESS SHOULD DECREASE. THERE SHOULD BE
A LULL IN THE WIND ONCE PRECIPITATION MOVES OUT LATE IN THE
AFTERNOON. THIS MIGHT BE A PERIOD WHERE AN IFR CIG OR IFR VSBYS
MIGHT OCCUR. WE LOWERED CIGS AND VSBYS DEEPER INTO MVFR LEVELS BUT
WERE NOT CONFIDENT TO GO IFR.
THE COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA FROM WEST TO
EAST APPROXIMATELY 23Z TO 02Z. ONCE IT DOES, VFR CONDITIONS
SHOULD RETURN, BUT ALSO SOME OCCASIONALLY GUSTY WEST WINDS.
OUTLOOK...
WEDNESDAY...VFR. NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO AROUND
30 KNOTS. SOME SNOW SHOWERS SHOULD BE NORTH AND WEST OF KABE.
THURSDAY...VFR. NORTH-NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO
AROUND 25 KNOTS, DIMINISHING AT NIGHT.
FRIDAY...CLOUDS INCREASE, THEREFORE VFR TO MVFR. SOME RAIN ARRIVES
MAINLY LATER IN THE DAY WITH IFR POSSIBLE, AND THERE COULD BE A
WINTRY MIX FOR A TIME MAINLY NORTH OF A KTTN TO KABE LINE.
EAST-SOUTHEAST WINDS NEAR 10 KNOTS.
SATURDAY...SUB-VFR WITH PERIODS OF RAIN POSSIBLE, WITH PERHAPS A
WINTRY MIX NORTH AND WEST OF KPHL. EASTERLY WINDS NEAR 10 KNOTS,
PROBABLY TURNING NORTHERLY AT NIGHT.
&&
.MARINE...
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH THE SHORT TERM.
WHILE AN APPROXIMATE 50 KT LLJ IS FORECAST TO MOVE OVER THE AREA
WATERS LATER TODAY, THE AIR MASS WILL BE WARMER THAN THE BAY AND
OCEAN TEMPS. SO WE ARE NOT EXPECTING EFFICIENT MIXING. IF WE ARE
WRONG, ITS LIKELY TO BE RIGHT ALONG THE IMMEDIATE COAST. HIGHER
CONFIDENCE ABOUT THE WIND SPEED FORECASTS FARTHER OFFSHORE.
THERE MIGHT BE A LULL IN THE WINDS THIS EVENING AS THE FRONT MOVES
THROUGH, BUT THEN SCA LEVEL WINDS (AS WELL AS SEAS CONTINUING ON THE
OCEAN) SHOULD COME BACK IN FULL SWING AFTER A SMALL TIME GAP.
OUTLOOK...
A COLD NORTHWESTERLY FLOW WILL OCCUR WEDNESDAY AND THURSDAY AS LOW
PRESSURE IS TO OUR NORTHEAST, ALLOWING FOR A TIGHTENED PRESSURE
GRADIENT TO BE IN PLACE. THIS WILL COMBINE WITH CAA, WHICH LOOKS TO
PEAK LATER WEDNESDAY BEFORE SOME MODERATION TAKES PLACE DURING
THURSDAY. THE FORECAST SOUNDINGS SHOW DEEPER MIXING OCCURRING AS WE
GO THROUGH WEDNESDAY, WITH A SOLID SMALL CRAFT ADVISORY EVENT
LOOKING TO OCCUR. THE FORECAST SOUNDINGS ALSO INDICATE THAT SOME
GALE FORCE GUSTS COULD OCCUR, HOWEVER IT LOOKS MARGINAL BASED ON THE
VERTICAL WIND PROFILES. WE THOUGHT ABOUT ISSUING A GALE WATCH FOR
WEDNESDAY NIGHT, HOWEVER WE WOULD LIKE TO SEE HIGHER WINDS WITHIN
THE MIXING LAYER. THEREFORE, WE WILL MAINTAIN THE SMALL CRAFT
ADVISORY BUT EXTEND IT THROUGH 11Z THURSDAY. THIS WILL PROBABLY NEED
TO BE EXTENDED THROUGH THURSDAY AS THE TIGHT PRESSURE GRADIENT HOLDS
FOR A TIME. THE WINDS START DIMINISHING LATER THURSDAY AS HIGH
PRESSURE CENTERED TO OUR NORTH ARRIVES. THE NEXT SYSTEM THOUGH IS
FORECAST TO ARRIVE LATER FRIDAY INTO SATURDAY, WITH WINDS
SHIFTING FROM NORTHERLY TO MORE OF AN EASTERLY DIRECTION.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ430-431-
450>455.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...GIGI/NIERENBERG
SHORT TERM...GIGI
LONG TERM...GORSE
AVIATION...GIGI/GORSE/NIERENBERG
MARINE...GIGI/GORSE
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
611 AM EST TUE FEB 19 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK FROM THE GREAT LAKES REGION TODAY, THEN
ACROSS SOUTHEASTERN CANADA TO NORTHERN NEW ENGLAND TONIGHT AND
WEDNESDAY. AN ASSOCIATED COLD FRONT WILL SLIDE ACROSS OUR AREA
THIS EVENING. HIGH PRESSURE FROM CENTRAL CANADA WILL THEN BUILD
SOUTH AND EASTWARD THURSDAY. THIS HIGH WILL BE SHIFTING EAST LATE
THURSDAY INTO FRIDAY, AS ANOTHER LOW PRESSURE SYSTEM MOVES INTO THE
GREAT LAKES AND OHIO VALLEY FRIDAY NIGHT INTO SATURDAY. LOW PRESSURE
FARTHER SOUTH ON THE COLD FRONT THEN EXITS THE MID ATLANTIC COAST
SATURDAY NIGHT INTO SUNDAY. HIGH PRESSURE THEN ARRIVES LATE SUNDAY
INTO MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE ESTF UPDATE SPED THE ARRIVAL OF PCPN SLIGHTLY FASTER. LOOKS
LIKE THE 06Z GFS WILL VERIFY PRETTY CLOSELY AT 12Z. SNOW WAS
FALLING RELATIVELY SOUTH IN SWRN PA, SO WE HAVE EXPANDED THE
MENTION FARTHER TO THE SOUTH. THE GOOD NEWS IS IF PRECIPITATION
ARRIVES FASTER, THIS WILL CUT BACK ON OUR WIND CONCERNS.
THE GFS INITIALIZATION LOOKED SLIGHTLY BETTER THAN THE WRF-NMMB AND
THE FORECAST PACKAGE WAS LEANED ABOUT THREE QUARTERS TOWARD ITS
TIMING. WE DID OPT FOR THE WRF-NMMB SFC THERMAL FIELDS OVER THE GFS
IN THE POCONOS.
THE OVERALL FORCING STILL LOOKS SPLIT. THE FCST ISENTROPIC LIFT IS
NOT ROBUST, THE MID LEVEL QVEC CONVERGENCE AND FGEN FORCING WEAKEN
AS IT MOVES ACROSS THE APPALACHIANS. THE LOW LEVEL THETA E RIDGE IS
NOT ANYTHING TO WRITE HOME FOR (PLENTY OF LOW SFC DEW POINTS INTO
GEORGIA). THE BEST "CONVECTIVE" CONTRIBUTION GOES NORTHWEST OF CWA.
WHAT IT STILL DOES HAVE GOING FOR IT IS THE EXIT REGION OF THE 250MB
JET. WE SAW WHAT THAT DID FOR THE SYSTEM LAST FRIDAY NIGHT AND WE
ARE COUNTING ON IT TO SAVE THE QPF DAY.
SENSIBLE WEATHER, WE START BRINGING IN THE POPS AT 14Z, CLOSER TO
THE GFS TIMING. THERE IS PLENTY OF DRY AIR FOR THIS MOISTURE TO
OVERCOME, SO WE BELIEVE IT WILL TAKE A COUPLE OF HOURS FOR PCPN TO
GET GOING (EARLY TO MID AFTERNOON). THIS ALSO COINCIDES BETTER WITH
THE JET. THE THETA E RIDGE GETS OFFSHORE PRETTY FAST AND THE FCST
MID LVL WAA IS WAY EAST BY 00Z, SO POPS WERE DROPPED LATE IN THE
AFTERNOON IN THE WEST.
FOR PTYPE, THE DRY AIR MASS IN PLACE WILL MAKE IT EASY TO EVAPORATE
COOL TO SNOW. THE QUESTION IS HOW DEEP WILL THE THERMAL SOUNDING
HAVE TO BE COOLED FOR SNOW. THE LATEST ACAR SOUNDING FROM PHL
ALREADY HAS THE FREEZING LEVEL ABOVE 6K. SO THE "MENTION" OF SNOW
WAS LIMITED TO THE PHL FAR NWRN SUBURBS, RARITAN BASIN IN NJ AND
POINTS NW. THE LATER ARRIVAL TIME AND LIKELY LIGHT INTENSITY
START HAS PRETTY MUCH REMOVED THE RISK FOR FREEZING RAIN.
THE ONLY LOCALE THAT SHOULD HANG ON TO SNOW ARE THE POCONOS WHERE
THE WRF/HI RES ARW/ AND HRRR ALL DROP SFC TEMPS TO FREEZING AND
LEVEL THEM THERE. LATE IN THE DAY SOME SOUNDINGS SUGGEST WE LOSE THE
ICE AND WITH LESSER INTENSITY AND A CONTINUING SOUTH WIND, THE SNOW
COULD MIX OR CHANGE TO RAIN EVEN THERE. AS MENTIONED ABOVE THE MID
LEVEL FGEN FORCING WEAKENS AND THE BEST FGEN FRCG THAT MAKES IT
ACROSS THE MOUNTAINS REMAINS TOWARD THE 500MB LEVEL, COMES AS NO
SURPRISE THAT THE BEST OMEGA IS FCST TO ABOVE THE SNOW GROWTH AREA.
THIS COMBINED WITH MODEL QPFS OF AROUND A QUARTER OF AN INCH SUGGEST
AN INCH OR TWO OF SNOW AS THE MOST LIKELY OUTCOME FOR THE HIGHER
TERRAIN IN THE POCONOS, SO NO ADVISORY WILL BE ISSUED AT THIS TIME.
OUR BIGGEST UNCERTAINTY REMAINS WITH THE WIND AND TO A CERTAIN
DEGREE ITS TIED TO THE TEMPERATURES. THE FORECAST SOUNDINGS REMAIN
VERY BULLISH ON DEEP MIXING AND ALBEIT TAKING THE HIGHER LEVEL OF
THE TWO BUFKIT MOMENTUM TRANSPORT WINDS GIVE US ADVISORY LEVEL WIND
GUSTS. OF LATE THE SFC GUSTS HAVE BEEN BETTER REPRESENTED BY THE
LOWER TRANSPORT GUST WHICH SUGGEST INTO THE 30S FOR GUSTS. THERE MAY
BE A WINDOW OF OPPORTUNITY FOR MORE ROBUST GUSTS THAN WE ARE
FORECASTING BEFORE THE SHOWERS ARRIVE AND MAKE THE SOUNDING MORE
ISOTHERMAL. THIS WILL DEPEND ON TEMPERATURES JUMPING THIS MORNING
BEFORE THE SHOWERS ARRIVE AND GETTING HIGHER THAN WE ARE CURRENTLY
ANTICIPATING. WHETHER ITS THE CHILLY BAYS OR OCEAN OR SKY COVER, MOS
GUIDANCE REMAINS PRETTY CONSERVATIVE WITH MAX TEMPS (AND WITH THE
WINDS TOO). WE STAYED CLOSE TO THEM NORTHWEST OF I95, BUT WERE MORE
BULLISH THAN BOTH SOUTHEAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
THE COLD FRONT SHOULD CLEAR OUR CWA EARLY THIS EVENING AND ANOTHER
COLD AIR MASS WILL START WORKING ITS WAY INTO OUR CWA. ANY POPS AWAY
FROM THE HIGHER TERRAIN WERE IN JUST EARLY IN THE EVENING. THERE
ARE MODEL DIFFERENCES AS TO HOW QUICKLY THE LAKE EFFECT MACHINE GETS
GOING. EVEN WITHOUT IT, THERE ARE ENOUGH SHORT WAVES MOVING THROUGH
TO LIKELY TRIGGER SOME SNOW SHOWERS NORTHWEST AND WE KEPT POPS GOING.
LIKE TODAY, WE THINK STAT GUIDANCE MAY BE A BIT TOO WEAK WITH THE
WINDS. GIVEN THE STRONG CAA, WE WENT HIGHER. IN TANDEM WE WERE ALSO
LOWER THAN STAT GUIDANCE WITH THE MIN TEMPS.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE SYNOPTIC SETUP IS AN ACTIVE ONE AND IS INITIALLY COMPRISED OF A
STRONG UPPER-LEVEL TROUGH IN THE NORTHEAST WITH ANOTHER ONE DIGGING
ACROSS THE INTERMOUNTAIN WEST. THE FIRST ONE EXITS THROUGH THURSDAY,
THEN THE BROADENING OF THE TROUGH IN THE WEST HAS SOME ENERGY THAT
EJECTS INTO THE PLAINS AND OHIO VALLEY. THIS SYSTEM MAY BECOME
STRETCHED OUT AS IT WEAKENS DUE TO THE MAIN TROUGH DAMPENING OUT
WHILE IT RELOADS ONCE AGAIN IN THE WEST. THE SOUTHERN JET LOOKS TO
REMAIN ACTIVE, THEREFORE ENERGY TRAVERSING THIS CORRIDOR WILL TEND
TO SLIDE OFF THE MID ATLANTIC COAST. WE MAY SEE THE SYSTEM ORGANIZE
MORE AS IT EXITS OFF THE MID ATLANTIC COAST DURING THE WEEKEND AS
SHORT WAVE ENERGY SHARPENS A BIT AND INCREASING BAROCLINIC EFFECTS
OCCUR. YET ANOTHER LARGE STORM LOOKS TO EJECT INTO THE PLAINS EARLY
NEXT WEEK WITH ITS COLD FRONT /OR EVEN OCCLUDED FRONT/ APPROACHING
FROM THE WEST MONDAY NIGHT. WE USED A MODEL BLEND FOR WEDNESDAY INTO
FRIDAY, THEN USED HPC GUIDANCE AND CONTINUITY THEREAFTER.
FOR WEDNESDAY AND THURSDAY...AN UPPER-LEVEL TROUGH IS FORECAST TO
DOMINATE THE NORTHEAST AS LOW PRESSURE TRACKS ACROSS SOUTHEASTERN
CANADA AND NEW ENGLAND, THEN EVENTUALLY TO THE CANADIAN MARITIMES.
THERE IS DECENT 850 MB CAA FORECAST WEDNESDAY BEFORE IT BACKS OFF
WEDNESDAY NIGHT AND THURSDAY. THE COMBINATION OF THE CAA AND A TIGHT
PRESSURE GRADIENT LEADS TO BLUSTERY CONDITIONS. THIS LOOKS SIMILAR
TO THIS PAST SUNDAY, HOWEVER THE MID LEVEL COLD CORE IS FORECAST TO
NOT BE QUITE AS COLD COMPARED TO SUNDAY. DESPITE THIS, VERTICAL
MIXING WILL DEEPEN WEDNESDAY AND THE FORECAST SOUNDINGS SHOW GUSTS
TO NEAR 35 KNOTS ARE CERTAINLY POSSIBLE. THE FLOW AT 925 MB IS
FORECAST TO BE MAINLY IN THE 30-35 KNOT RANGE WITH SOME HIGHER WINDS
AT 850 MB. IF WE ARE ABLE TO MIX EVEN DEEPER, THEN SOME NEAR ADVISORY
LEVEL GUSTS /40 KNOTS/ WILL BE POSSIBLE. WE WOULD LIKE TO SEE
WINDS CLOSER TO 50 KNOTS AT 850 MB FOR ADVISORY LEVEL WINDS,
THEREFORE WE WILL CONTINUE WITH GUSTS UNDER CRITERIA HOWEVER IT
WILL STILL BE A BLUSTERY/WINDY DAY.
THE GUSTY WINDS SHOULD CONTINUE WEDNESDAY NIGHT DESPITE WHEN WE
TYPICALLY SEE THEM DECOUPLE. THE PRESENT OF ENOUGH OF A MIXED LAYER
WILL KEEP AT LEAST SOME WIND GOING THROUGH THE NIGHT. THE AIRMASS
STARTS TO MODIFY DURING THURSDAY HOWEVER THE WESTERN EDGE OF THE MID
LEVEL COLD CORE IS NEARBY AND THIS WILL STILL COMBINE WITH A
LINGERING TIGHTENED PRESSURE GRADIENT TO RESULT IN BRISK CONDITIONS.
THESE WINDS WILL EASE UP AND BECOME NORTHERLY LATER THURSDAY AS HIGH
PRESSURE BUILDS DOWN FROM NEAR THE GREAT LAKES.
THE CAA ALONG WITH A NORTHWEST FLOW WILL PRODUCE LAKE EFFECT SNOW
DOWNWIND OF LAKES ERIE AND ONTARIO. THIS FLOW LOOKS CONDUCIVE TO
CARRY SOME STREAMERS INTO NORTHEASTERN PENNSYLVANIA, THEREFORE WE
WILL CARRY HIGHER CHC POPS INTO THE POCONOS FOR AT LEAST SCATTERED
SNOW SHOWERS. THIS SHOULD EASE UP ESPECIALLY THURSDAY AS THE AIRMASS
STARTS TO MODIFY AND THE FLOW MAY TURN MORE NORTHERLY.
FOR FRIDAY AND SATURDAY...THERE IS GENERALLY LOWER CONFIDENCE DURING
THIS TIME FRAME AS OUR SENSIBLE WEATHER IS FROM ENERGY THAT BECOMES
STRETCHED OUT FROM THE MIDWEST TO THE OHIO VALLEY AND SOUTHWARD.
HIGH PRESSURE CENTERED ACROSS SOUTHEASTERN CANADA LOOKS TO BE WEDGED
DOWN INTO THE MID ATLANTIC FOR A TIME FRIDAY. THIS MAY RESULT IN
SOME COLDER LOW-LEVEL AIR REMAINING WHILE WARMING TAKES PLACE ALOFT.
THE PRECIPITATION SHIELD WITH THIS INCOMING SYSTEM MAY END UP
SPLITTING, WITH THE MORE ORGANIZED AREA TO OUR SOUTH. WHILE WE HAVE
WAA, THE ISENTROPIC UPGLIDE AND ASSOCIATED LARGE SCALE ASCENT LOOKS
WEAKER OVER OUR AREA. THIS COULD JUST RESULT IN SOME LIGHT
PRECIPITATION. THERE LOOKS TO BE ENOUGH DRY AIR IN PLACE AHEAD OF
THIS FEATURE, WHERE THE PRECIPITATION DOES NOT START UNTIL LATER IN
THE DAY FRIDAY.
THERE DOES LOOK TO BE ENOUGH ENERGY IN THE SOUTHWEST FLOW ALOFT TO
ORGANIZE A SURFACE LOW, WHICH THEN TRACKS TO OUR SOUTH SATURDAY.
THIS COULD KEEP MORE OF AN EASTERLY WIND ACROSS OUR AREA ALONG WITH
COOLER TEMPERATURES. AT THIS JUNCTURE, PRECIPITATION LOOKS TO BE ON
THE LIGHT TO MODERATE SIDE UNLESS THE SYSTEM TRACKING OFF THE MID
ATLANTIC COAST CAN STRENGTHEN SOME MORE WHICH RESULTS IN STRONGER
LIFT SPREADING NORTHWARD. THE ECMWF IS INDICATING THIS POTENTIAL BUT
ALSO MAINTAINS THE PROGRESSIVE LOOK AS WELL. GIVEN MORE UNCERTAINTY
IN THE QPF AMOUNTS AND THERMAL FIELDS, WE DID NOT CHANGE MUCH FROM
CONTINUITY. OVERALL, MAINLY SOME RAIN ACROSS THE SOUTHERN AREAS WITH
THE CHC FOR A WINTRY MIX AT TIMES FARTHER NORTH.
FOR SUNDAY...LOW PRESSURE SHOULD BE EXITING THE MID ATLANTIC COAST
DURING THE MORNING AS A SHORT WAVE TROUGH AMPLIFIES SOME. THERE IS
SOME GUIDANCE THAT SUGGESTS THE SYSTEM IS SLOWER/A BIT STRONGER AND
THEREFORE INTRODUCES MORE PRECIPITATION FOR SUNDAY. AS OF NOW, WE
FOLLOWED HPC`S LEAD AND KEPT THE CONSOLIDATED SURFACE LOW EXITING TO
OUR EAST SUNDAY MORNING. THIS WOULD MEAN PERHAPS SOME PRECIPITATION
TO START, THE HIGH PRESSURE BEGINS TO BUILD IN. THE OVERALL
UPPER-LEVEL TROUGH DOES NOT LOOK TO AMPLIFY MUCH OVER OUR AREA
DURING THIS TIME FRAME, THUS THE FLOW BEING PROGRESSIVE. SOME COOLER
AIR LOOKS TO TRY AND SETTLE SOUTHWARD AS THE SURFACE LOW EXITS,
THEREFORE PERHAPS SOME MIXED PRECIPITATION OR SNOW BEFORE IT ENDS
ACROSS THE NORTH ESPECIALLY. WE DID NOT MAKE TO MANY CHANGES DUE TO
LOWER CONFIDENCE IN THE DETAILS.
FOR MONDAY...THE ACTIVE PATTERN CONTINUES AND THIS FEATURES
AN AMPLIFYING UPPER-LEVEL TROUGH MOVING EASTWARD. THIS WILL DRIVE
LOW PRESSURE ACROSS THE PLAINS MONDAY. THIS SYSTEM LOOKS TO
OCCLUDE WITH ANOTHER SURFACE LOW DEVELOPING FARTHER SOUTH ALONG THE
TRIPLE POINT. THERE IS A DECENT RIDGE BUILDING DOWNSTREAM OF THE
TROUGH, AND THIS WOULD HELP TO PULL MORE MOISTURE NORTHWARD AHEAD OF
THE FRONTAL BOUNDARY. THE LARGE SCALE LIFT LOOKS STRONGER WITH THIS
SYSTEM, AND IT COULD BE ENHANCED SOME AS THE SOUTHERN SURFACE LOW
TRACKS NORTHEASTWARD. WE WENT WITH A DRY MONDAY AS MID LEVEL RIDGING
ARRIVES, ALTHOUGH CLOUDS WILL INCREASE MAINLY LATE.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
THE 12Z TAFS WERE AGAIN SLIGHTLY FASTER WITH THE PCPN STARTER BUT
OTHERWISE CONTINUE THE IDEAS OF LLWS AND MORE GUSTINESS ALONG WITH
A DROP INTO MVFR LEVELS ONCE PRECIPITATION STARTS.
FOR THE FIRST PART OF THE MORNING, CLOUDS WILL COME IN FAST. WE
ADDED THE CHANCE OF SOME SNOW AT THE START AT KRDG AND KABE. LLWS
WAS CONTINUED FROM THE START WITH A SW LLJ AVERAGING 40 TO 45 KTS.
DURING THE SECOND HALF OF THE MORNING WE ARE FORECASTING SHOWERS
TO SPREAD ACROSS THE REST OF THE TERMINALS AND REACHING ACY BY
18Z. CONDITIONS WHEN SHOWERS FIRST ARRIVE ARE VFR TO OUR WEST. THE
FORECAST SOUNDINGS ARE SHOWING CONSIDERABLE GUSTINESS. WE WENT
WITH THE MORE CONSERVATIVE SUGGESTION. CONFIDENCE IS LOWER THAN
AVERAGE ABOUT THE WIND GUSTS. UNIDIRECTIONAL SOUTH WINDS, SO ONCE
THE GUSTINESS STARTS, THE LLWS SHOULD END.
DURING THE AFTERNOON WE BROUGHT THE TERMINALS DOWN INTO MVFR AS
THE MORE WIDESPREAD AND HEAVIER SHOWERS MOVE ACROSS THE REGION. AS
THE SHOWERS MOVE IN, THE GUSTINESS SHOULD DECREASE. THERE SHOULD BE
A LULL IN THE WIND ONCE PRECIPITATION MOVES OUT LATE IN THE
AFTERNOON. THIS MIGHT BE A PERIOD WHERE AN IFR CIG OR IFR VSBYS
MIGHT OCCUR. WE LOWERED CIGS AND VSBYS DEEPER INTO MVFR LEVELS BUT
WERE NOT CONFIDENT TO GO IFR.
THE COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA FROM WEST TO
EAST APPROXIMATELY 23Z TO 02Z. ONCE IT DOES, VFR CONDITIONS
SHOULD RETURN, BUT ALSO SOME OCCASIONALLY GUSTY WEST WINDS.
OUTLOOK...
WEDNESDAY...VFR. NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO AROUND
30 KNOTS. SOME SNOW SHOWERS SHOULD BE NORTH AND WEST OF KABE.
THURSDAY...VFR. NORTH-NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO
AROUND 25 KNOTS, DIMINISHING AT NIGHT.
FRIDAY...CLOUDS INCREASE, THEREFORE VFR TO MVFR. SOME RAIN ARRIVES
MAINLY LATER IN THE DAY WITH IFR POSSIBLE, AND THERE COULD BE A
WINTRY MIX FOR A TIME MAINLY NORTH OF A KTTN TO KABE LINE.
EAST-SOUTHEAST WINDS NEAR 10 KNOTS.
SATURDAY...SUB-VFR WITH PERIODS OF RAIN POSSIBLE, WITH PERHAPS A
WINTRY MIX NORTH AND WEST OF KPHL. EASTERLY WINDS NEAR 10 KNOTS,
PROBABLY TURNING NORTHERLY AT NIGHT.
&&
.MARINE...
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH THE SHORT TERM.
WHILE AN APPROXIMATE 50 KT LLJ IS FORECAST TO MOVE OVER THE AREA
WATERS LATER TODAY, THE AIR MASS WILL BE WARMER THAN THE BAY AND
OCEAN TEMPS. SO WE ARE NOT EXPECTING EFFICIENT MIXING. IF WE ARE
WRONG, ITS LIKELY TO BE RIGHT ALONG THE IMMEDIATE COAST. HIGHER
CONFIDENCE ABOUT THE WIND SPEED FORECASTS FARTHER OFFSHORE.
THERE MIGHT BE A LULL IN THE WINDS THIS EVENING AS THE FRONT MOVES
THROUGH, BUT THEN SCA LEVEL WINDS (AS WELL AS SEAS CONTINUING ON THE
OCEAN) SHOULD COME BACK IN FULL SWING AFTER A SMALL TIME GAP.
OUTLOOK...
A COLD NORTHWESTERLY FLOW WILL OCCUR WEDNESDAY AND THURSDAY AS LOW
PRESSURE IS TO OUR NORTHEAST, ALLOWING FOR A TIGHTENED PRESSURE
GRADIENT TO BE IN PLACE. THIS WILL COMBINE WITH CAA, WHICH LOOKS TO
PEAK LATER WEDNESDAY BEFORE SOME MODERATION TAKES PLACE DURING
THURSDAY. THE FORECAST SOUNDINGS SHOW DEEPER MIXING OCCURRING AS WE
GO THROUGH WEDNESDAY, WITH A SOLID SMALL CRAFT ADVISORY EVENT
LOOKING TO OCCUR. THE FORECAST SOUNDINGS ALSO INDICATE THAT SOME
GALE FORCE GUSTS COULD OCCUR, HOWEVER IT LOOKS MARGINAL BASED ON THE
VERTICAL WIND PROFILES. WE THOUGHT ABOUT ISSUING A GALE WATCH FOR
WEDNESDAY NIGHT, HOWEVER WE WOULD LIKE TO SEE HIGHER WINDS WITHIN
THE MIXING LAYER. THEREFORE, WE WILL MAINTAIN THE SMALL CRAFT
ADVISORY BUT EXTEND IT THROUGH 11Z THURSDAY. THIS WILL PROBABLY NEED
TO BE EXTENDED THROUGH THURSDAY AS THE TIGHT PRESSURE GRADIENT HOLDS
FOR A TIME. THE WINDS START DIMINISHING LATER THURSDAY AS HIGH
PRESSURE CENTERED TO OUR NORTH ARRIVES. THE NEXT SYSTEM THOUGH IS
FORECAST TO ARRIVE LATER FRIDAY INTO SATURDAY, WITH WINDS
SHIFTING FROM NORTHERLY TO MORE OF AN EASTERLY DIRECTION.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 6 AM EST
THURSDAY FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...GIGI
SHORT TERM...GIGI
LONG TERM...GORSE
AVIATION...GIGI/GORSE
MARINE...GIGI/GORSE
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
733 AM EST TUE FEB 19 2013
.AVIATION...
//DISCUSSION...
STRONG SOUTHWEST WIND AND FALLING TEMPERATURE WILL BE THE MAIN
AVIATION CONCERN DURING THE MORNING AS MID LEVEL DRY AIR INITIALLY
KEEPS SNOW SHOWERS AT A MINIMUM. CEILING WILL REMAIN NO BETTER
THAN MVFR, HOWEVER, AND THEN SNOW WILL INCREASE IN COVERAGE AND
INTENSITY DURING THE LATE MORNING AND THROUGH THE AFTERNOON, ALL
WHILE WESTERLY WIND GUSTS INCREASE TO ABOUT 35 KNOTS. IFR
VISIBILITY RESTRICTION IN SNOW AND BLOWING SNOW IS LIKELY AT FNT
AND MBS INTO THE EARLY EVENING BEFORE BOTH THE SNOW AND THE WIND
GUSTS DIMINISH THROUGH TONIGHT. MVFR CEILING AND SOME FLURRIES OFF
THE SOUTH END OF LAKE MICHIGAN WILL BE POSSIBLE IN THE DTW AREA
TOWARD SUNRISE WEDNESDAY.
FOR DTW... A POCKET OF SNOW IN THE CHICAGO AREA AT PRESS TIME WILL
MOVE THROUGH SOUTHERN MICHIGAN DURING THE MORNING AND INTO THE DTW
AREA BY NOON WHILE WESTERLY WIND GUSTS CONTINUE IN THE 30 TO 35 KNOT
RANGE. EXPECT ACCUMULATION TO BE LESS THAN AN INCH DURING THE
AFTERNOON WITH THIS ACTIVITY AS TEMPERATURES FALL IN THE MID AND
UPPER 20S.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET TODAY THROUGH TONIGHT.
* HIGH CONFIDENCE IN SNOW AS PRECIPITATION TYPE TODAY AND TONIGHT.
&&
.PREV DISCUSSION...ISSUED 347 AM EST TUE FEB 19 2013
SHORT TERM... TODAY AND TONIGHT
MILD AND WET CONDITIONS THROUGHOUT SE MICHIGAN DURING THE EARLY
MORNING WILL BE KICKED OUT OF THE AREA BY A STRONG COLD FRONT
PASSING THROUGH AROUND SUNRISE. THE MAIN CONCERN WITH THIS FRONT
WILL BE PEAK WIND GUSTS REACHING 45 MPH ADVISORY CRITERIA IN THE
STRONG WESTERLY FLOW BEHIND IT, BUT THE COMBINATION OF FALLING
TEMPERATURES AND SNOW SHOWERS WILL ALSO ADD A LAYER OF HARSHNESS TO
CONDITIONS THROUGH THE DAY. EXPECT TEMPERATURES TO FALL TOWARD THE
MID AND UPPER 20S BY LATE MORNING, STRUGGLE TO REMAIN IN THE 20S
DURING THE AFTERNOON WITH SINGLE DIGIT WIND CHILL, AND THEN GIVE WAY
TO LOWS WELL DOWN INTO THE TEENS TONIGHT WITH WIND CHILL ABOUT 5
BELOW AFTER MIDNIGHT.
UPSTREAM OBSERVATIONS, ALONG WITH MODEL ISALLOBARIC FIELDS, INDICATE
THE STRONGEST WIND GUSTS OF 40 TO 50 KNOTS OVER CENTRAL INDIANA
OCCURRED WITHIN THE STEEPEST ISALLOBARIC GRADIENT ASSOCIATED WITH A
PEAK 3 HOUR PRESSURE RISE STARTING OFF CLOSE TO 10 MB. THIS PRESSURE
RISE CENTER IS SHOWN TO WEAKEN FROM NEARLY 10 MB TO 3-4 MB IN THE
NAM12 AND HIGH RES RAP MODELS AS THE FRONT MOVES THROUGH WESTERN
LOWER MICHIGAN AND THE REST OF INDIANA AND OHIO. THIS WEAKENING OF
THE ISALLOBARIC COMPONENT OF DYNAMIC FORCING WILL LIKELY RESULT IN A
SHORTER DURATION OF PEAK GUSTS AROUND 45 MPH IN OUR AREA ALONG AND
IMMEDIATELY POST FRONT. AFTER THAT, EXPECT A FEW HOURS OF WIND GUSTS
LESS THAN 40 MPH UNTIL COLD ADVECTION AND SYSTEM RELATIVE ISENTROPIC
DESCENT RAMPS UP LEADING TO STEEPENING LAPSE RATES IN A DEEPENING
BOUNDARY LAYER. DOWNWARD MOMENTUM TRANSPORT WILL THEN BE SUFFICIENT
FOR GUSTS TO REACH 45 MPH AGAIN BY LATE MORNING THROUGH THE
AFTERNOON. GUSTS WILL DIMINISH BY TONIGHT BUT WILL REMAIN IN THE 30
MPH RANGE AS THE BOUNDARY LAYER REMAINS WELL MIXED AFTER SUNSET.
AFTER THE DRY SLOT KEEPS SNOW AT BAY DURING THE MORNING, AN
EXPANSIVE AREA OF MID LEVEL MOISTURE WRAPPING AROUND THE WESTERN
FLANK OF THE LOW WILL DRIVE THE PATTERN OF SNOW DURING THE AFTERNOON
THROUGH TONIGHT. EARLY MORNING RADAR COMPOSITES SHOW THIS COMING
TOGETHER OVER THE UPPER MIDWEST AT PRESS TIME ADDING CONFIDENCE TO
THE EXPECTATION OF A HIGH POP/LOW ACCUMULATION SCENARIO. THIS
MOISTURE WILL SEED ENHANCEMENT FROM LAKE MICHIGAN AS INSTABILITY
INCREASES INTO THE 15-20C RANGE FOR LAKE TO 850 MB DELTA-T. THE MAIN
LIMITING FACTOR WILL BE THE STRONG WIND SPEED AND STEADY VEERING
TREND THAT WILL PREVENT ANY DOMINANT BAND FORMATION. PLAN TO FAVOR
THE TRI CITIES AND THUMB WITH CATEGORICAL POPS DURING THE AFTERNOON
AND LIKELY INTO THE THE EVENING WITH 1 TO 2 INCHES OF ACCUMULATION
BEFORE THE WIND SHIFT TOWARD THE NORTHWEST FAVORS AREAS SOUTH OF
INTERSTATE 69 TOWARD SUNRISE WEDNESDAY.
LONG TERM...
ALTHOUGH THE 500 MB LOW/MID LEVEL COLD POOL WILL BE MOVING INTO NEW
ENGLAND ON WEDNESDAY...A SHALLOW (SFC-925 MB) BACK DOOR COLD FRONT
WILL ATTEMPT TO MAKE INROADS INTO SOUTHERN LOWER MICHIGAN.
925 MB TEMPS OF -16 TO -17 C FORECASTED TO WORK THROUGH THE THUMB
REGION...WITH LOW LEVEL FLOW JUST SLIGHTLY WEST OF DUE NORTH.
SO...REASONABLE EXPECTATION SOME LAKE EFFECT SNOW SHOWER ACTIVITY
WILL BRUSH THE SHORELINE...BUT SHALLOW NATURE OF THE ACTIVITY
(MODERATING 850 MB TEMPS) SHOULD PREVENT ACTIVITY FROM GETTING OUT
OF HAND. 1042 MB HIGH OVER ONTARIO WILL NOSE INTO SOUTHEAST MICHIGAN
ON THURSDAY...AS AMPLIFIED UPPER LEVEL RIDGE MOVES OVER THE WESTERN
GREAT LAKES. POTENT UPPER WAVE JUST OFF THE PACIFIC NORTHWEST COAST
EARLY THIS MORNING STILL PROGGED TO ROTATE THROUGH THE FOUR CORNERS
REGION LATE WEDNESDAY...BUT TRACKING JUST A TOUCH FARTHER
EAST...OVER/NEAR SIOUX FALLS SOUTH DAKOTA THURSDAY NIGHT (PER 00Z
GFS/EURO). DRAMATIC WEST-EAST SHEARING OF THE UPPER LEVEL
CIRCULATION WILL OCCUR...BUT STILL A PERIOD OF LARGE SCALE ASCENT/PV
ADVECTION FRIDAY MORNING TO OCCUR OVER SOUTHEAST MICHIGAN. THE BULK
OF THE LIFT WILL BE USED UP JUST TO SATURATE THE LOW LEVELS...AS THE
PREVIOUSLY MENTIONED HIGH OVER ONTARIO LEADS TO EASTERLY DRY LOW
LEVEL FLOW PERSISTING INTO FRIDAY. 00Z GFS NOT EVEN GIVING US A
TENTH OF AN INCH OF QPF...AS DEEPER MOISTURE SEEN IN THE 850-700
MB/PW FIELDS SKIRTS JUST TO THE SOUTHEAST OF THE CWA. STILL...DECENT
SHOT OF MOISTURE ADVECTION...AND PREFERENCE IS WITH THE STRONGER
CANADIAN/EURO WHICH MAINTAINS THE 500 MB LOW OVER MINNESOTA INTO THE
FIRST HALF OF THE WEEKEND. QPF FROM THOSE MODELS SUPPORTS A SOLID 1
TO TWO INCHES OF SNOW ON FRIDAY...WITH RELATIVELY LOW SNOW TO LIQUID
RATIOS...AS ZERO OR SLIGHTLY BETTER 850 MB TEMPS SEEN REACHING THE
OHIO BORDER.
THE MODEST MID LEVEL COLD POOL OVER MINNESOTA WILL BREAK OFF TO THE
EAST FOR THE WEEKEND...KEEPING TEMPERATURES IN CHECK...AS 850 MB
TEMPS LOOK TO BE HOVERING AROUND -10 C...AND WITH LIMITED
SUNSHINE...MAXES EXPECTED TO REMAIN GENERALLY BELOW 40 DEGREES.
ALTHOUGH...WE WILL HAVE THE DRY SLOT WORKING THROUGH SATURDAY
MORNING...WHICH COULD BE THE DAY WE SNEAK UP TO 40 DEGREES.
MARINE...
DEEP LOW PRESSURE MOVING THROUGH THE STRAITS WILL PULL A STRONG COLD
FRONT THROUGH LAKE HURON AND LOWER MICHIGAN EARLY IN THE MORNING.
WESTERLY GALES WILL DEVELOP AFTER THE FRONTAL PASSAGE AND THEN
PERSIST TONIGHT THROUGH WEDNESDAY WHILE VEERING TO NORTHWEST OVER
THE OPEN WATERS OF LAKE HURON. POLAR AIR SURGING BACK INTO THE
REGION WILL CHANGE RAIN BACK TO SNOW AND ALSO LEAD TO A SUBSTANTIAL
FREEZING SPRAY HAZARD OVER THE OPEN WATERS TONIGHT THROUGH
WEDNESDAY. THE STRONG WINDS AND RESULTING LARGE WAVES WILL COMBINE
WITH NEAR IDEAL WATER TEMPERATURE FOR WIDESPREAD FREEZING SPRAY TO
BECOME HEAVY. MARINE CONDITIONS WILL THEN IMPROVE CONSIDERABLY BY
THURSDAY AS HIGH PRESSURE SETTLES OVER THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055-MIZ060-
MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075-MIZ076-MIZ082-
MIZ083...UNTIL 7 PM TUESDAY.
LAKE HURON...
GALE WARNING...LHZ361...FROM NOON TUESDAY TO 7 PM WEDNESDAY.
HEAVY FREEZING SPRAY WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-
LHZ464...FROM 7 PM TUESDAY TO 7 PM WEDNESDAY.
GALE WARNING...LHZ362-LHZ363...UNTIL 7 PM WEDNESDAY.
GALE WARNING...LHZ421-LHZ422-LHZ441-LHZ442-LHZ443-LHZ462-LHZ463-
LHZ464...UNTIL MIDNIGHT WEDNESDAY.
LAKE ST CLAIR...
GALE WARNING...UNTIL MIDNIGHT WEDNESDAY.
MI WATERS OF LAKE ERIE...
GALE WARNING...UNTIL MIDNIGHT WEDNESDAY.
&&
$$
AVIATION.....BT
SHORT TERM...BT
LONG TERM....SF
MARINE.......BT
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
722 AM EST TUE FEB 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 539 AM EST TUE FEB 19 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
HUDSON BAY THROUGH NW ONTARIO INTO WI/IL WAS BECOMING MORE
NEGATIVELY TILTED AS A 120 KT 300-250 JET MOVES FROM THE OHIO VALLEY
TOWARD THE EASTERN LAKES. THE BACK EDGE OF A WELL-DEFINED WARM
CONVEYOR SHIELD EXTENDED FROM NEAR CMX-DTW. UPPER LEVEL DIV WITH A
COUPLED JET STRUCTURE AND STRONG DEEP LAYER QVECTOR CONV SUPPORTED A
LARGE AREA OF MODERATE SNOW ACROSS LAKE SUPERIOR AND UPPER MI INTO
NRN WI. AT THE SFC...LOW PRES WAS DEEPENING AS IT MOVED THROUGH NRN
LAKE SUPERIOR AND AT 10Z WAS AROUND 987 MB NEAR BEAVER ISLAND. THE
TIGHTENING GRADIENT BETWEEN THE LOW AND A 1040 MB RIDGE OVER
MANITOBA INTO THE NRN PLAINS HAS RESULTED IN VERY GUSTY WINDS WITH
P59 ALREADY RECORDING GUSTS TO 49 MPH. RELATIVELY LOW SLR VALUES
NEAR 10/1 AND THE STRONG WINDS FRACTURING SNOW FLAKES HAVE KEPT SNOW
AMOUNTS GENERALLY IN THE 2 TO 3 INCH RANGE.
THE MODERATE TO STRONG 700-300 QVECTOR CONV AND FAVORABLE 280K-290K
ISENTROPIC LIFT INTO CNTRL AND EAST UPPER MICHIGAN WILL CONTINUE
WITH WIDESPEAD SYNOPTIC SNOW CONTINUING. ADDITIONAL SYNOPTIC QPF
VALUES OF AROUND 0.10 TO 0.20 INTO THE NRN CWA SHOULD PROVIDE
POTENTIAL FOR AN ADDITIONAL 1 TO 3 INCHES. LOW LEVEL CAA WITH 850 MB
TEMPS DROPPING INTO THE -15C TO -17C RANGE WILL BRING ADDITIONAL
LAKE ENHANCED SNOW FOR LOCATIONS FAVORED BY CYCLONIC 340-330 FLOW.
THIS WOULD AFFECT MOST OF NORTHERN UPPER MICHIGAN WITH LOW LEVEL
CONV FOCUSED NEAR THE MARQUETTE COUNTY SHORLINE AND INTO WRN ALGER
COUNTY. ADDITIONAL AMOUNTS FROM LAKE ENHANCED SNOW OF 1 TO 3 INCHES
ARE ALSO EXPECTED.
THE MAIN HAZARD HOWEVER...WILL BE THE VERY STRONG WINDS AS MODEL
MOMENTUMM TRANSFER PROFILES SUGGEST THAT WINDS WILL GUST IN THE
30-40 MPH RANGE...ESPECIALLY THIS MORNING. ALONG THE LAKESHORE EVEN
HIGHER GUSTS WILL BE POSSIBLE...IN THE 40-50 MPH RANGE. THE
COMBINATION OF THE WINDS AND FALLING SNOW WILL PRODUCE VERY LOW
VISIBILITIES WITH NEAR WHITEOUT CONDITIONS AT TIMES IN OPEN/EXPOSED
AREAS. THE BLOWING SNOW/VISIBILITY HAZARD WAS ENOUGH TO JUSTIFY UPGRADE
OF MARQUETTE-BAGARAG WINTER WEATHER ADVISORIES TO WINTER STORM
WARNINGS EVEN WITH RELATIVELY MODEST ADDITIONAL SNOW AMOUNTS.
A TRANSITION FROM LAKE ENHANCED CLOSER TO PURE LAKE EFFECT SNOW IS
EXPECTED FROM THIS AFTERNOON INTO TONIGHT AS THE SYNOPTIC SCALE LIFT
WEAKENS AND DEPARTS TO THE EAST. THE GRADIENT WILL ALSO ONLY
GRADUALLY WEAKEN...KEEPING THE THREAT OF BLSN GOING. ADDITIONAL
AMONTS IN THE 1 TO 4 INCH RANGE NORTH ARE EXPECTED WITH LCLY HIGHER
AMOUNTS IN THE 4 TO 7 INCH RANGE POSSIBLE FROM FAR ERN MARQUETTE
COUNTY INTO ALGER COUNTY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 539 AM EST TUE FEB 19 2013
LOW PRESSURE OVER LOWER LAKES BEGINS TO UNRAVEL ON WEDNESDAY AS
UPPER TROUGH SURGES EAST WITH MAIN JET ENERGY OUT AHEAD OF TROUGH
VERSUS DIGGING INTO THE BACK SIDE OF THE TROUGH. CYCLONIC FLOW
STEADILY WEAKENS THROUGH THE DAY AND H8-H7 MOISTURE WILL BE ON THE
DOWNWARD TREND. EXPECT VIGOROUS LK ENHANCED SNOW TO BEGIN THE DAY TO
FADE BY LATE AFTN/EARLY WED EVENING. ADDITIONAL SNOW AMOUNTS
WEDNESDAY SHOULD BE IN THE MORE MODERATE RANGE AS NEGATIVE FACTORS
PUT CRIMP IN LK EFFECT INSENSITY THROUGH THE DAY. NNW WINDS GUSTING
OVER 30 MPH RESULT IN MORE BLSN/REDUCED VSBY FOR MAINLY EASTERN AREAS
BUT THIS TOO WILL IMPROVE BY WEDNESDAY EVENING. ORIGINALLY THOUGHT
THE 00Z THU EXPIRATION TIME OF WARNING WAS TOO LONG...BUT DUE TO
ONLY A GRADUAL DECREASING TREND IN SNOW/WIND...IT APPEARS IN GOOD
SHAPE.
1040MB HIGH PRESSURE OVER ONTARIO SLIDES BY INTO WESTERN QUEBEC
THROUGH THURSDAY NIGHT. RESULT IS WEAK NORTH TO NORTHEAST WINDS AT
SFC THROUGH 925MB. INVERSION LESS THAN 3KFT EASILY...BUT STILL ENOUGH
OVER-WATER INSTABILITY IN MOIST LAYER TO KEEP SMALL CHANCES FOR LK
EFFECT GOING OVR NCNTRL UPR MICHIGAN OVERNIGHT WED NIGHT THROUGH THU
MORNING. LOW-LEVEL WINDS BECOMES DIFFLUENT OVR WEST ENOUGH TO BREAK
UP LINGERING CLOUDS EVEN AS 925MB WINDS REMAIN ONSHORE. MIN TEMPS
OVR INTERIOR WEST PROBABLY END UP BLO ZERO. SINGLE DIGITS TO LOWER
TEENS ABOVE ZERO ELSEWHERE.
MODELS INSISTENT ON SHOWING SHARP SOUTHERN STREAM SHORTWAVE TROUGH
LIFTING THROUGH MID MISSISSIPPI AND LOWER MISSOURI RIVER VALLEY ON
THURSDAY AND INTO UPR GREAT LAKES ON FRIDAY. SYSTEM EXPECTED TO LOSE
BIG PART OF ITS PUNCH FROM THE HEAVY SNOW THAT IS FORECAST OVER
CNTRL PLAINS ON THURSDAY BY TIME IT REACHES UPR LAKES. DIMINISHING
TREND MOSTLY DUE TO DECREASING MOISTURE AS H7 MIXING RATIOS OVER
4G/KG ARE SHUNTED MORE INTO TENNESSEE RIVER AND OHIO RIVER VALLEYS
WITH MIXING RATIOS LESS THAN 2.5G/KG MAKING IT INTO UPR MICHIGAN.
SYSTEM IS ALSO RUNNING INTO RIDGING ALOFT. ENOUGH CONFIDENCE IT WILL
SNOW OVER SOUTH CWA TO INCREASE POPS TO LIKELY. COORD WITH DLH/GRB
ON THIS. CHANCE POPS ELSEWHERE WITH INDICATION THERE MAY BE SHARP
CUTOFF TO NORTHERN EDGE OF SNOW. LINGERING SFC-H5 TROUGH SLIDES
ACROSS UPR LAKES THROUGH SATURDAY...SO KEPT SMALL CHANCES IN THE
FORECAST. NO BIG ORGANIZED SNOWS ARE IN STORE THOUGH...JUST PATCHY
SNOW AND/OR SNOW SHOWERS. TEMPS WILL BE WARMING WITH DAYTIME HIGHS
BOTH SATURDAY AND SUNDAY POSSIBLY PUSHING PAST 30 DEGREES.
HIGH PRESSURE BUILDS IN TO CLOSE THE WEEKEND THEN ANOTHER SOUTHERN
STREAM SYSTEM MAY TAKE AIM ON UPR MICHIGAN EARLY NEXT WEEK. RIGHT
NOW THAT SYSTEM LOOKS TO HAVE SIMILAR EVOLUTION AS ONE MOVING
THROUGH ON FRIDAY. WE SHALL SEE. MODEL TIMING ISSUES EVIDENT FOR THE
ARRIVAL OF SNOW SO USED CONSENSUS POPS AT THIS POINT. WITH SOUTHERN
STREAM ORIGIN...TEMPERATURES WILL LIKELY BE AT OR ABOVE NORMAL FOR
NEXT WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 717 AM EST TUE FEB 19 2013
CMX...EXPECT PREDOMINANT VLIFR CONDITIONS AS VERY STRONG NNW WINDS
COMBINE WITH LAKE ENHANCED SNOW TO PRODUCE NEAR BLIZZARD CONDITIONS
AT TIMES FOR MUCH OF TODAY. THE WINDS MAY DIMINISH ENOUGH THIS
EVENING FOR SOME IMPROVEMENT WITH LIFR/IFR CONDITIONS.
SN/BLSN WILL ALSO KEEP MAINLY IFR/LIFR CONDITIONS AT IWD.
HOWEVER...THERE MAY BE SOME IMPROVEMENT LATER TODAY AS THE WINDS
SLOWLY DIMINISH ONCE THE LO SHIFTS FARTHER TO THE E.
SAW...EXPECT PREDOMINANT IFR/LIFR CONDITIONS. AS THE LOW PULLS OFF
TO THE E LATER TONIGHT AND INTENSIFIES...THE COMBINATION OF FALLING
SN/BLSN FROM AN INCREASING NW WIND WILL CAUSE LIFR CONDITIONS THRU THE
MRNG. THERE MAY BE SOME IMPROVEMENT IN THE AFTERNOON ONCE THE DEEPER
MOISTURE EXITS AND THE DOWNSLOPE FLOW HELPS REDUCE THE SNOW
INTENSITY. HOWEVER...GUSTY WINDS/BLSN MAKE IFR CONDITIONS LIKELY
THROUGH THIS EVENING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 539 AM EST TUE FEB 19 2013
STRONG WRAPPED UP SFC LOW NEARS STRAITS THIS MORNING AND HEADS
TOWARD WESTERN QUEBEC TONIGHT WHILE BEGINNING TO WEAKEN. MSLP AS LOW
AS 986MB THIS MORNING. VERY TIGHT PRESSURE GRADIENT PRESENT THROUGH
THIS EVENING FROM SSM TO DLH...POSSIBLY EXCEEDING AN IMPRESSIVE 25
MB INTO THE AFTN. SUCH A STRONG GRADIENT COMBINED WITH COLD AIR
ADVECTION AND STRONG WINDS ALOFT LEAD TO STRONG GALES WITH FREQUENT
STORM FORCE GUSTS OVER CNTRL LK SUPERIOR. CURRENT STORM AND GALE
WARNINGS IN FINE SHAPE. WINDS WILL BE SLOW TO DIMINISH WITH GALES
PERSISTING OVER 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 STORM WARNING UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT FOR
MIZ002-004-005-009-084.
WINTER STORM WARNING UNTIL 5 PM EST WEDNESDAY FOR MIZ006-007-014-
085.
WINTER STORM WARNING UNTIL 7 AM EST WEDNESDAY FOR MIZ001-003.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MIZ013.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ THURSDAY
FOR LSZ162-240>251-263>267.
GALE WARNING UNTIL 7 PM EST WEDNESDAY FOR LSZ245>251-265-267.
STORM WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ266.
STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LSZ243-244-264.
GALE WARNING UNTIL 5 AM EST /4 AM CST/ WEDNESDAY FOR LSZ240>242-
263.
GALE WARNING UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR LSZ162.
LAKE MICHIGAN...
GALE WARNING UNTIL 7 AM EST WEDNESDAY FOR LMZ248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...JLB
MARINE...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
543 AM EST TUE FEB 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 539 AM EST TUE FEB 19 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
HUDSON BAY THROUGH NW ONTARIO INTO WI/IL WAS BECOMING MORE
NEGATIVELY TILTED AS A 120 KT 300-250 JET MOVES FROM THE OHIO VALLEY
TOWARD THE EASTERN LAKES. THE BACK EDGE OF A WELL-DEFINED WARM
CONVEYOR SHIELD EXTENDED FROM NEAR CMX-DTW. UPPER LEVEL DIV WITH A
COUPLED JET STRUCTURE AND STRONG DEEP LAYER QVECTOR CONV SUPPORTED A
LARGE AREA OF MODERATE SNOW ACROSS LAKE SUPERIOR AND UPPER MI INTO
NRN WI. AT THE SFC...LOW PRES WAS DEEPENING AS IT MOVED THROUGH NRN
LAKE SUPERIOR AND AT 10Z WAS AROUND 987 MB NEAR BEAVER ISLAND. THE
TIGHTENING GRADIENT BETWEEN THE LOW AND A 1040 MB RIDGE OVER
MANITOBA INTO THE NRN PLAINS HAS RESULTED IN VERY GUSTY WINDS WITH
P59 ALREADY RECORDING GUSTS TO 49 MPH. RELATIVELY LOW SLR VALUES
NEAR 10/1 AND THE STRONG WINDS FRACTURING SNOW FLAKES HAVE KEPT SNOW
AMOUNTS GENERALLY IN THE 2 TO 3 INCH RANGE.
THE MODERATE TO STRONG 700-300 QVECTOR CONV AND FAVORABLE 280K-290K
ISENTROPIC LIFT INTO CNTRL AND EAST UPPER MICHIGAN WILL CONTINUE
WITH WIDESPEAD SYNOPTIC SNOW CONTINUING. ADDITIONAL SYNOPTIC QPF
VALUES OF AROUND 0.10 TO 0.20 INTO THE NRN CWA SHOULD PROVIDE
POTENTIAL FOR AN ADDITIONAL 1 TO 3 INCHES. LOW LEVEL CAA WITH 850 MB
TEMPS DROPPING INTO THE -15C TO -17C RANGE WILL BRING ADDITIONAL
LAKE ENHANCED SNOW FOR LOCATIONS FAVORED BY CYCLONIC 340-330 FLOW.
THIS WOULD AFFECT MOST OF NORTHERN UPPER MICHIGAN WITH LOW LEVEL
CONV FOCUSED NEAR THE MARQUETTE COUNTY SHORLINE AND INTO WRN ALGER
COUNTY. ADDITIONAL AMOUNTS FROM LAKE ENHANCED SNOW OF 1 TO 3 INCHES
ARE ALSO EXPECTED.
THE MAIN HAZARD HOWEVER...WILL BE THE VERY STRONG WINDS AS MODEL
MOMENTUMM TRANSFER PROFILES SUGGEST THAT WINDS WILL GUST IN THE
30-40 MPH RANGE...ESPECIALLY THIS MORNING. ALONG THE LAKESHORE EVEN
HIGHER GUSTS WILL BE POSSIBLE...IN THE 40-50 MPH RANGE. THE
COMBINATION OF THE WINDS AND FALLING SNOW WILL PRODUCE VERY LOW
VISIBILITIES WITH NEAR WHITEOUT CONDITIONS AT TIMES IN OPEN/EXPOSED
AREAS. THE BLOWING SNOW/VISIBILITY HAZARD WAS ENOUGH TO JUSTIFY UPGRADE
OF MARQUETTE-BAGARAG WINTER WEATHER ADVISORIES TO WINTER STORM
WARNINGS EVEN WITH RELATIVELY MODEST ADDITIONAL SNOW AMOUNTS.
A TRANSITION FROM LAKE ENHANCED CLOSER TO PURE LAKE EFFECT SNOW IS
EXPECTED FROM THIS AFTERNOON INTO TONIGHT AS THE SYNOPTIC SCALE LIFT
WEAKENS AND DEPARTS TO THE EAST. THE GRADIENT WILL ALSO ONLY
GRADUALLY WEAKEN...KEEPING THE THREAT OF BLSN GOING. ADDITIONAL
AMONTS IN THE 1 TO 4 INCH RANGE NORTH ARE EXPECTED WITH LCLY HIGHER
AMOUNTS IN THE 4 TO 7 INCH RANGE POSSIBLE FROM FAR ERN MARQUETTE
COUNTY INTO ALGER COUNTY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 539 AM EST TUE FEB 19 2013
LOW PRESSURE OVER LOWER LAKES BEGINS TO UNRAVEL ON WEDNESDAY AS
UPPER TROUGH SURGES EAST WITH MAIN JET ENERGY OUT AHEAD OF TROUGH
VERSUS DIGGING INTO THE BACK SIDE OF THE TROUGH. CYCLONIC FLOW
STEADILY WEAKENS THROUGH THE DAY AND H8-H7 MOISTURE WILL BE ON THE
DOWNWARD TREND. EXPECT VIGOROUS LK ENHANCED SNOW TO BEGIN THE DAY TO
FADE BY LATE AFTN/EARLY WED EVENING. ADDITIONAL SNOW AMOUNTS
WEDNESDAY SHOULD BE IN THE MORE MODERATE RANGE AS NEGATIVE FACTORS
PUT CRIMP IN LK EFFECT INSENSITY THROUGH THE DAY. NNW WINDS GUSTING
OVER 30 MPH RESULT IN MORE BLSN/REDUCED VSBY FOR MAINLY EASTERN AREAS
BUT THIS TOO WILL IMPROVE BY WEDNESDAY EVENING. ORIGINALLY THOUGHT
THE 00Z THU EXPIRATION TIME OF WARNING WAS TOO LONG...BUT DUE TO
ONLY A GRADUAL DECREASING TREND IN SNOW/WIND...IT APPEARS IN GOOD
SHAPE.
1040MB HIGH PRESSURE OVER ONTARIO SLIDES BY INTO WESTERN QUEBEC
THROUGH THURSDAY NIGHT. RESULT IS WEAK NORTH TO NORTHEAST WINDS AT
SFC THROUGH 925MB. INVERSION LESS THAN 3KFT EASILY...BUT STILL ENOUGH
OVER-WATER INSTABILITY IN MOIST LAYER TO KEEP SMALL CHANCES FOR LK
EFFECT GOING OVR NCNTRL UPR MICHIGAN OVERNIGHT WED NIGHT THROUGH THU
MORNING. LOW-LEVEL WINDS BECOMES DIFFLUENT OVR WEST ENOUGH TO BREAK
UP LINGERING CLOUDS EVEN AS 925MB WINDS REMAIN ONSHORE. MIN TEMPS
OVR INTERIOR WEST PROBABLY END UP BLO ZERO. SINGLE DIGITS TO LOWER
TEENS ABOVE ZERO ELSEWHERE.
MODELS INSISTENT ON SHOWING SHARP SOUTHERN STREAM SHORTWAVE TROUGH
LIFTING THROUGH MID MISSISSIPPI AND LOWER MISSOURI RIVER VALLEY ON
THURSDAY AND INTO UPR GREAT LAKES ON FRIDAY. SYSTEM EXPECTED TO LOSE
BIG PART OF ITS PUNCH FROM THE HEAVY SNOW THAT IS FORECAST OVER
CNTRL PLAINS ON THURSDAY BY TIME IT REACHES UPR LAKES. DIMINISHING
TREND MOSTLY DUE TO DECREASING MOISTURE AS H7 MIXING RATIOS OVER
4G/KG ARE SHUNTED MORE INTO TENNESSEE RIVER AND OHIO RIVER VALLEYS
WITH MIXING RATIOS LESS THAN 2.5G/KG MAKING IT INTO UPR MICHIGAN.
SYSTEM IS ALSO RUNNING INTO RIDGING ALOFT. ENOUGH CONFIDENCE IT WILL
SNOW OVER SOUTH CWA TO INCREASE POPS TO LIKELY. COORD WITH DLH/GRB
ON THIS. CHANCE POPS ELSEWHERE WITH INDICATION THERE MAY BE SHARP
CUTOFF TO NORTHERN EDGE OF SNOW. LINGERING SFC-H5 TROUGH SLIDES
ACROSS UPR LAKES THROUGH SATURDAY...SO KEPT SMALL CHANCES IN THE
FORECAST. NO BIG ORGANIZED SNOWS ARE IN STORE THOUGH...JUST PATCHY
SNOW AND/OR SNOW SHOWERS. TEMPS WILL BE WARMING WITH DAYTIME HIGHS
BOTH SATURDAY AND SUNDAY POSSIBLY PUSHING PAST 30 DEGREES.
HIGH PRESSURE BUILDS IN TO CLOSE THE WEEKEND THEN ANOTHER SOUTHERN
STREAM SYSTEM MAY TAKE AIM ON UPR MICHIGAN EARLY NEXT WEEK. RIGHT
NOW THAT SYSTEM LOOKS TO HAVE SIMILAR EVOLUTION AS ONE MOVING
THROUGH ON FRIDAY. WE SHALL SEE. MODEL TIMING ISSUES EVIDENT FOR THE
ARRIVAL OF SNOW SO USED CONSENSUS POPS AT THIS POINT. WITH SOUTHERN
STREAM ORIGIN...TEMPERATURES WILL LIKELY BE AT OR ABOVE NORMAL FOR
NEXT WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1255 AM EST TUE FEB 19 2013
IWD/CMX...EXPECT PREDOMINANT IFR CONDITIONS AT TAF ISSUANCE WITH -SN
FALLING TO GIVE WAY TO LIFR/PERHAPS VLIFR WX EARLY THIS MRNG THRU
MUCH OF TODAY AS THE ARRIVAL OF MUCH COLDER AIR ON THE HEELS OF VERY
GUSTY NW WINDS CAUSES LK ENHANCED SN/EXTENSIVE BLSN...WITH NEAR
BLIZZARD CONDITIONS AT TIMES IN THESE LOCATIONS EXPOSED TO NW WIND.
IWD IS LIKELY TO SEE SOME IMPROVEMENT LATER TODAY AS THE WINDS
SLOWLY DIMINISH ONCE THE LO SHIFTS FARTHER TO THE E.
SAW...EXPECT PREDOMINANT IFR/LIFR CONDITIONS EARLY THIS MRNG AS AREA
OF SN ASSOCIATED WITH LO PRES MOVING THRU THE UPR LKS IMPACTS THIS
LOCATION. AS THE LO PULLS OFF TO THE E LATER TNGT AND INTENSIFIES...
THE COMBINATION OF FALLING SN/BLSN FROM AN INCRSG NW WIND WL CAUSE
LIFR CONDITIONS THRU THE MRNG. THERE MAY BE SOME IMPROVEMENT IN THE
AFTN ONCE THE DEEPER MSTR EXITS AND THE DOWNSLOPE FLOW EASES THE
PCPN INTENSITY. BUT GUSTY WINDS/BLSN MAKE IFR CONDITIONS LIKELY THRU
THIS EVNG.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 539 AM EST TUE FEB 19 2013
STRONG WRAPPED UP SFC LOW NEARS STRAITS THIS MORNING AND HEADS
TOWARD WESTERN QUEBEC TONIGHT WHILE BEGINNING TO WEAKEN. MSLP AS LOW
AS 986MB THIS MORNING. VERY TIGHT PRESSURE GRADIENT PRESENT THROUGH
THIS EVENING FROM SSM TO DLH...POSSIBLY EXCEEDING AN IMPRESSIVE 25
MB INTO THE AFTN. SUCH A STRONG GRADIENT COMBINED WITH COLD AIR
ADVECTION AND STRONG WINDS ALOFT LEAD TO STRONG GALES WITH FREQUENT
STORM FORCE GUSTS OVER CNTRL LK SUPERIOR. CURRENT STORM AND GALE
WARNINGS IN FINE SHAPE. WINDS WILL BE SLOW TO DIMINISH WITH GALES
PERSISTING OVER 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 STORM WARNING UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT FOR
MIZ002-004-005-009-084.
WINTER STORM WARNING UNTIL 5 PM EST WEDNESDAY FOR MIZ006-007-014-
085.
WINTER STORM WARNING UNTIL 7 AM EST WEDNESDAY FOR MIZ001-003.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MIZ013.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ THURSDAY
FOR LSZ162-240>251-263>267.
GALE WARNING UNTIL 7 PM EST WEDNESDAY FOR LSZ245>251-265-267.
STORM WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ266.
STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LSZ243-244-264.
GALE WARNING UNTIL 5 AM EST /4 AM CST/ WEDNESDAY FOR LSZ240>242-
263.
GALE WARNING UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR LSZ162.
LAKE MICHIGAN...
GALE WARNING UNTIL 7 AM EST WEDNESDAY FOR LMZ248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...KC
MARINE...JLA
AREA FORECAST DISCUSSION
NWS DULUTH MN
610 AM CST TUE FEB 19 2013
.AVIATION.../12Z TAF ISSUANCE/
MAINLY VFR CIGS...WITH AREAS OF MVFR CEILINGS AROUND 2 KFT WITH 3-5
SM VSBY DUE TO BLSN...WILL PREVAIL THIS MORNING. SKIES WILL CLEAR
FROM THE WEST THROUGH THE AFTERNOON AS MUCH DRIER AIR FILTERS INTO
THE REGION. ALTHOUGH WIND SPEEDS WILL DIMINISH A BIT THIS
MORNING...THE STRONG NORTHWEST WINDS CONTINUE TODAY...RELAXING
DURING THE EVENING HOURS AS HIGH PRESSURE SETTLES INTO THE
NORTHLAND OVERNIGHT.
&&
.PREV DISCUSSION... /ISSUED 321 AM CST TUE FEB 19 2013/
CURRENT...VERY DEEP MID LVL TROF CONTINUES TO AMPLIFY AS IT CRAWLS
ACROSS CWA EARLY THIS MORNING. SFC LOW OVER ERN WISC IS INTENSIFYING
AS IT MOVES TOWARDS ERN END OF LAKE SUPERIOR. LARGE SHIELD OF DEEP
LAYER MOISTURE ACCOMPANIED BY COLD ADVECTION IS KEEPING LIGHT SNOW
ACROSS REGION. A STANDING WAVE IS INDICATED... ACROSS DOUGLAS COUNTY
AND INTO SE CARLTON COUNTY NEAR HOLYOKE... IN THE ANIMATED 88D
REFL/VEL PRODUCTS AS NW FLOW INCREASES. SFC PRESS GRADIENT NEARLY
20MB ACROSS CWA WITH GUSTY WINDS ACROSS MOST OF MN ZONES. VERY
STRONG GUSTS ALONG NORTH SHORE FROM TWIN PORTS TO GRAND PORTAGE.
LOCAL KATABATIC ENHANCEMENT OCCURING FROM SILVER BAY NORTH TO BORDER
WHERE INLAND TERRAIN IS HIGHER. GUST OVER 50 MPH HAVE OCCURED IN
THIS CORRIDOR WITH HRRR 3KM OUTPUT SUGGESTING GUSTS MAY REACH 60 MPH
THROUGH EARLY MORNING. ARCTIC AIR HAS INFILTRATED THE NORTHWESTERN
CWA WITH SFC TEMPS BELOW ZERO. WINDCHILL ADVISORY MAY NOT VERIFY IN
MANY AREAS UNTIL BETWEEN 12Z-15Z WHEN MIN TEMPS ARE REACHED AND WIND
SPEEDS REMAIN RELATIVELY HIGH. .
TODAY/TONIGHT...SLOW MOVING MID LVL TROF WILL KEEP A CYCLONIC AND
RELATIVELY MOIST CIRCULATION OVER THE REGION. GUSTY WINDS ARE EXPECTD
TO CONTINUE AS SFC PRESS GRADIENT REMAINS QUITE LARGE ACROSS CWA.
BUFKIT MOMENTUM TRANSFER PROFILES SHOW GUSTS MAY LINGER WELL INTO
THE NIGHT AS WELL. NORTH SHORE STILL SUSCEPTIBLE TO KATABATIC
ENHANCEMENT OFF HIGHER PLATEAU WEST OF LAKE SUPERIOR...ESPECIALLY
COOK COUNTY THROUGH MID MORNING. DEEP LAYER DRYING WILL OCCUR FROM
WEST TO EAST TODAY OVER THE MN ZONES. MAIN STORY OVER WISC WILL BE
CONTINUATION OF LES ACROSS SNOW BELTS. LAKE INDUCED CAPE FORECAST
TO INCREASE TO 400/500 J/KG THIS AFTN. INVERSION HEIGHTS ARE
EXPECTED TO LIFT TO ABOUT 4K FT THIS AFTERNOON BEFORE LOWERING TO 2K
FT AFTER MDINIGHT TONIGHT. WILL KEEP CURRENT ADVISORY/WARNING FOR
SOUTH SHORE. WILL NEED ANOTHER WIND CHILL ADVISORY TONIGHT FOR MOST
OF CWA. WILL LET DAY SHIFT ISSUE THIS AFTER CURENT WINDC ADV EXPIRES.
MAX TEMPS TODAY WILL STRUGGLE ALL DAY TO GET ABOVE ZERO ACROSS THE
BORDERLAND AND IRON RANGE. SINGLE DIGITS ELSEWHERE. LOWERED PREVIOUS
TEMP FCST OVER INTERIOR WISC IN LINE WITH ECBC VALUES AND LOWER
TEMPS OF SREF PLUMES.
TOMORROW...PROGRESSIVE FLOW ALOFT WILL SEND A MID LVL RIDGE
OVERHEAD. STRONG SFC HIGH CENTERED OVER NRN ONTARIO WILL BUILD SOUTH
INTO CWA. ABUNDANT SUNSHINE TO START THE DAY ALTHOUGH HIGH CLOUDS
MAY INCREASE FROM THE SOUTHWEST IN THE AFTERNOON IN RESPONSE TO
UPPER LEVEL WARM ADVECTION FROM SRN ROCKIES STORM. TEMPS REMAIN
WELL BELOW CLIMO.
LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY.
FOCUS IN LONG TERM ON ACTIVE PATTERN FOR THE UPPER MIDWEST LATE IN
THE WEEK...AND EARLY NEXT WEEK.
UPPER LEVEL RIDGE WILL AMPLIFY OVER THE WRN GREAT LAKE REGION WED
NIGHT AS A VORT MAX ROUNDS THE BASE OF A LONG WAVE TROUGH IN THE SW
CONUS...DEEPENING INTO A CLOSED LOW AS IT LIFTS ACROSS THE CENTRAL
PLAINS THURSDAY. THE 00Z MODELS ARE SHOWING GOOD AGREEMENT THAT THE
H50 LOW PUSHES INTO THE SRN DAKOTAS/MINN THURSDAY
EVENING...CENTERING OVER MINNESOTA FRIDAY NIGHT. MEANWHILE...THE SFC
LOW REMAINS TO THE SW OF THE H50 LOW...TRACKING ACROSS IOWA THROUGH
THE DAY FRIDAY...REACHING UPPER MICHIGAN/CEN GREAT LAKES FRIDAY
NIGHT. HAVE MADE VERY LITTLE CHANGES TO POPS THURSDAY NIGHT/FRIDAY
AS THE LEADING EDGE OF THE MAIN SWATH OF SNOW IS EXPECTED TO IMPACT
THE SRN DLH ZONES THURSDAY EVENING...LIFTING OVER MUCH OR ALL OF THE
NORTHLAND THROUGH FRIDAY. TEMPERATURE PROFILES CONTINUE TO SUGGEST
PTYPE OF ALL SNOW FOR THE DLH CWA.
ALTHOUGH UNCERTAINTY REMAINS...MODELS HAVE SHOWN DECENT RUN TO RUN
AGREEMENT THAT A BAND OF HEAVY SNOW DEVELOPS ACROSS THE SRN HALF OF
MINNESOTA THURSDAY NIGHT INTO FRIDAY MORNING. LATEST GFS/ECM
CONTINUE TO SHOW VERY DRY AIR ASSOCIATED WITH A RIDGE AXIS EXTENDING
SOUTH FROM ONTARIO WILL BE DIFFICULT TO ERODE THURSDAY NIGHT...SO
HAVE TRENDED A WITH A SLOWER TIMING FOR INTRODUCING POPS. THE LATEST
NAM BUFR SOUNDING AT KBRD/KINL/KHYR DEPICT PWATS INITIALLY THURSDAY OF
ONLY 0.08". HOWEVER...THERE IS MOISTURE ASSOCIATED WITH THE LOW THAT
DOES ADVECT INTO THE REGION AS THE H50 LOW APPROACHES...ALLOWING
PWATS TO INCREASE TO AROUND 0.3" THROUGH FRIDAY NIGHT AT MOST
LOCATIONS.
HAVE INCREASED TO BROADBRUSH LIKELY POPS FOR LIGHT SNOW FRIDAY.
MODELS SUGGEST THE H50 LOW HANGS AROUND THE GREAT LAKES REGION
THROUGH THE WEEKEND...KEEPING CYCLONIC FLOW...CLOUDS AND LIGHT SNOW
CHANCES FOR THE NORTHLAND.
ALTHOUGH THE GFS IS SHOWING A TREND TOWARDS THE ECM SOLUTION FOR THE
SYSTEM THAT WILL IMPACT THE REGION EARLY NEXT WEEK...THERE REMAINS
LARGE DIFFERENCES IN TIMING AND STORM TRACK. THE ECM SOLUTION LIFTS
THE CLOSED LOW OVER THE DAKOTAS TUESDAY...WHILE THE LATEST GFS
SUGGESTS A FASTER AND MORE EASTERLY TRACK WITH THE H50 LOW PASSING
OVER MINN/WIS MONDAY NIGHT.
&&
.POINT TEMPS/POPS...
DLH 4 -12 13 4 / 20 10 0 0
INL 1 -24 8 -11 / 10 10 0 0
BRD 4 -14 13 -3 / 10 10 0 0
HYR 8 -14 15 -8 / 30 10 0 0
ASX 10 -8 15 -1 / 60 40 20 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WIND CHILL ADVISORY UNTIL NOON CST TODAY FOR MNZ010>012-018>021-
025-026-033>037.
WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR WIZ004.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ002.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ003.
&&
$$
AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
949 AM EST TUE FEB 19 2013
.SYNOPSIS...
COLDER AIR WILL MOVE INTO THE REGION TODAY. HIGH PRESSURE WILL
BUILD ACROSS THE AREA TONIGHT THROUGH THURSDAY. AN ELEVATED WARM
FRONT WILL APPROACH THE AREA THURSDAY NIGHT...BRINGING WITH IT A
WINTRY MIX OF PRECIPITATION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SYNOPTIC SCALE PCPN HAS PUSHED EAST OF THE REGION THIS MORNING. WE
WILL FIND OURSELVES IN POST FRONTAL CAA FOR THE REMAINDER OF THE
DAY. LOW LEVEL MOISTURE LOCATED WITHIN THE DENDRITIC GROWTH ZONE
COMBINED WITH STEEPENING LOW LEVEL LAPSE RATES WILL BRING A CHANCE
OF SNOW SHOWERS TO THE REGION...WITH THE GREATEST CHANCE ACROSS THE
NRN ZONES. SNOW AMOUNTS WILL BE LIGHT. THERE HAS BEEN A CONCERN
ABOUT WIND AND WIND GUSTS AS A TIGHT PRESSURE GRADIENT REMAINS.
LATEST MOMENTUM TRANSFER TECHNIQUES SUGGEST WIND GUSTS SHOULD STAY
IN THE 30 TO 35 KNOT RANGE ACROSS THE NORTH AND 25 TO 30 ACROSS
THE SOUTH...SO WILL CONTINUE TO HIGHLIGHT THIS IN THE HWO AND
PERHAPS A SPS PRODUCT. HAVE SLOWED DOWN THE CLEARING ACRS THE SW
INTO THIS EVENING AS LOW LEVEL MOISTURE IS EXPECTED TO LINGER
LONGER.
AS FOR TEMPERATURES...HAVE SIDED MORE WITH THE LATEST RAP WHICH
HAS TEMPERATURES SLOWLY FALLING THROUGHOUT THE DAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
COLD ADVECTION WITH GUSTY WINDS WILL CONTINUE INTO THE
EVENING...WITH A GRADUAL DECREASE IN WIND SPEEDS. ANY LINGERING
SNOW SHOWERS...MAINLY ACROSS THE NORTH...WILL BEGIN TO DIMINISH
DURING THE EVENING AS THE MOISTURE FEED FROM THE GREAT LAKES CUTS
OFF FROM OUR AREA AND HIGH PRESSURE NOSES ITS WAY EASTWARD.
SKIES WILL BEGIN TO CLEAR FROM SOUTHWEST TO NORTHEAST LATE
TONIGHT. THE COLDER AIRMASS MOVING INTO PLACE WILL ALLOW
TEMPERATURES TO DROP INTO THE TEENS ACROSS MOST OF OUR ZONES
TONIGHT.
THE RIDGE AXIS WILL FINALLY BE CENTERED FROM NORTH TO SOUTH ACROSS
THE OHIO VALLEY WEDNESDAY THROUGH THURSDAY. WITH THE EXCEPTION OF
ONGOING MOIST FLOW ACROSS THE LAKES BRINGING CLOUDS TO THE
NORTHEASTERN ZONES ON WEDNESDAY...SKIES WILL BE PARTLY CLOUDY DURING
THIS TIME PERIOD. TEMPERATURES WILL REMAIN SEASONABLY COOL UNDER
THIS RIDGE...WITH MEAN DAYTIME/NIGHTTIME TEMPERATURES RUNNING
ABOUT 10 DEGREES BELOW NORMAL.
THE ATTENTION THEN TURNS TO A STORM SYSTEM LIFTING NORTHWARD
ACROSS THE PLAINS THURSDAY NIGHT. MID LEVEL RIDGING WILL AMPLIFY
DOWNSTREAM OF THIS STORM THURSDAY NIGHT...BRINGING A DEVELOPING
ELEVATED WARM FRONT ACROSS THE REGION. PRECIPITATION WILL SPREAD
ACROSS THE REGION LATE THURSDAY EVENING AND OVERNIGHT THURSDAY
NIGHT...CONTINUING INTO FRIDAY MORNING. MODELS HAVE COME INTO
BETTER AGREEMENT ON THIS TIMING OVER THE PAST COUPLE OF RUNS.
WITH SURFACE HIGH PRESSURE PROVIDING COLD EASTERLY FLOW INTO OUR
AREA AS THE ELEVATED WARM FRONT LIFTS TOWARD THE OHIO
VALLEY...THERE WILL BE THE OPPORTUNITY FOR A PERIOD OF WINTRY
PRECIPITATION TO OCCUR. CURRENT INDICATIONS ARE THAT A SUFFICIENTLY
DEEP WARM LAYER WILL BE PRESENT ACROSS PARTS OF THE FORECAST AREA
TO ALLOW FOR EITHER SLEET OR FREEZING RAIN TO OCCUR AT THE SURFACE
DURING THE OVERNIGHT HOURS THURSDAY NIGHT. THERE WILL BE A
TRANSITION ZONE BETWEEN THE SHALLOWER WARM LAYER ACROSS THE
NORTH...WHERE MOSTLY SLEET WILL BE POSSIBLE...TO THE CENTRAL
ZONES...WHERE MOSTLY FREEZING RAIN WILL BE POSSIBLE...AND THE
SOUTH WHERE SURFACE TEMPERATURES WILL BE ABOVE FREEZING...YIELDING
RAIN. THIS FORECAST IS BASED ON CURRENT MODEL TRENDS AT 60 HOURS
OUT...THEREFORE MORE ADJUSTMENTS WILL BE ON THE WAY AS THE TIME
DRAWS NEARER FOR THIS STORM SYSTEM...AND SUBSEQUENT MODEL RUNS
COME IN. WILL CONTINUE TO HIGHLIGHT THIS SYSTEM IN THE HWO FOR THE
TIME BEING.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
BEST LIFT AND QPF ARE STILL FORECAST TO LIFT N OF THE REGION ON
FRIDAY...AS A WRMFNT GRADUALLY BRINGS IN WARMER AIR ON FRI.
AS MENTIONED YESTERDAY...SECONDARY SYSTEM THAT WAS LIFTING ACROSS
THE SE U.S. OVER THE WEEKEND HAS TRENDED NWD FOR FRI NGT INTO SAT...
SO INTRODUCED CHC POPS FOR THE SE COUNTIES. RIGHT NOW THE PCPN TYPE
LOOKS LIKE RAIN. HIGH PRESSURE LOOKS LIKE IT WILL FINALLY BUILD IN
FOR SUNDAY. ANOTHER CDFNT IS FORECAST TO SWING INTO THE OH VALLEY
MONDAY...BUT THE GFS AND ECMWF ARE SHOWING DIFFERENCES...SO RIGHT
NOW JUST HAVE A MENTION OF CHANCE POPS FOR MONDAY.
THE COOL SE FLOW ON THU WILL KEEP HIGHS IN THE 30S. LOWS THU NGT IN
THE STORM SHOULD RANGE FROM THE MID 20S IN THE N TO LOWER 30S IN NRN
KY. HIGHS FRIDAY SHOULD MAKE THE 40S AS THE REGION GETS WARM
SECTORED. SOME LOCATIONS IN THE NRN KY MIGHT SEE 50S. EXPECT 40S
OVER THE WEEKEND FOR HIGHS WITH LOWS IN THE UPPER 20S TO LOWER 30S
SATURDAY MORNING AND 25 TO 30 SUNDAY MORNING. HIGHS SHOULD BEGIN TO
WARM FOR SUNDAY AND MONDAY REACHING THE MID 40S TO MID 50S BY MONDAY.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
THE COLD FRONT IS CURRENTLY PUSHING INTO CENTRAL OHIO AND WILL BE
EAST OF ALL OF THE TAF SITES BY 12Z. COLD AIR MOVING QUICKLY IN
BEHIND THE FRONT IS CHANGING PCPN OVER TO SNOW FOR A HALF HOUR OR
SO BEFORE TAPERING OFF. THIS COULD AFFECT KCMH/KLCK BRIEFLY AT THE
START OF THE TAF PERIOD WITH SOME IFR CIGS/VSBYS POSSIBLE.
OTHERWISE...EXPECT MVFR CIGS TO HANG IN THROUGH THE DAY WITH A FEW
SNOW SHOWERS OR FLURRIES POSSIBLE...PRIMARILY AT THE NORTHERN TAF
SITES. THE LOW LEVELS WILL BEGIN TO DRY OUT FROM THE SOUTHWEST
OVERNIGHT. THIS SHOULD ALLOW FOR AT LEAST SOME PARTIAL CLEARING TO
DEVELOP THROUGH THE OVERNIGHT HOURS FROM SOUTHWEST TO NORTHEAST
ACROSS THE AREA. CAA PATTERN TODAY WILL ALLOW FOR GUSTY WEST
WINDS TO PERSIST THROUGH THIS AFTERNOON...BEFORE GRADUALLY
DECREASING OVERNIGHT.
OUTLOOK...A WINTRY MIX IS LIKELY TO OCCUR THURSDAY NIGHT INTO
FRIDAY MORNING WITH SOME SNOW AND ICE ACCUMULATION POSSIBLE. IN
ADDITION MVFR CEILINGS AND VISIBILITIES WILL BE LIKELY WITH A
PERIOD OF IFR CONDITIONS POSSIBLE. MVFR CEILINGS MAY CONTINUE
THROUGH FRIDAY NIGHT AND INTO SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...LATTO
NEAR TERM...HICKMAN
SHORT TERM...LATTO
LONG TERM...SITES
AVIATION...JGL
AREA FORECAST DISCUSSION
NWS MEDFORD OR
237 AM PST TUE FEB 19 2013
.DISCUSSION...COOLING CLOUD TOPS AT THE LEADING EDGE OF THE UPPER
COLD POOL ARE MOVING ONSHORE NOW AS A VIGOROUS UPPER LOW SPINS ITS
WAY INTO OUR AREA. SHOWERS WILL INCREASE IN COVERAGE AND INTENSITY
OVER THE COAST AND INTO INTERIOR WEST SIDE SECTIONS THROUGH DAWN.
SURFACE TEMPERATURES ARE CURRENTLY PERILOUSLY CLOSE TO COLD ENOUGH
FOR SNOW IN MANY LOCATIONS, BUT BOTH THE NAM AND RAP FORECAST
SOUNDINGS MAINTAIN A LAYER OF ABOVE FREEZING TEMPERATURES THROUGH
THE MORNING. WILL BE FORCING A RAIN/SNOW MIX INTO THE WEATHER
GRIDS THIS MORNING OVER ELEVATIONS ABOVE 1000 FEET, BUT AM NOT
EXPECTING ANY ACCUMULATION, IN FACT, IT MAY BE ALL RAIN.
THE GOING WINTER WEATHER HEADLINES LOOK OK TO CONTINUE, ESPECIALLY
OVER THE KALMIOPSIS AND WESTERN SISKIYOU COUNTY AS THE MODELS
BRING A SLUG OF MOISTURE INTO THE MOUNTAINS THERE TODAY. ON THE
EAST SIDE, IT`S A BIT MORE TENUOUS. UPSLOPE SNOW WILL CONTINUE IN
THE WARNERS, BUT SNOW OVER THE VALLEYS WILL BE MUCH LIGHTER WITH
MINIMAL IMPACTS. THE ADVISORIES ARE MOSTLY CONFINED TO THE
MOUNTAINS ANYWAY, SO WILL LET THEM RIDE. THE OTHER ASPECT OF
TODAY`S SYSTEM IS THE INSTABILITY, WHICH LOOKS TO BE PRETTY GOOD,
ESPECIALLY OVER THE WATERS. THE CENTER OF THE UPPER COLD POOL (500
MB TEMPS OF -36C) MOVES OVER THE RELATIVELY WARMER WATERS THIS
MORNING AND THEN INTO NW CALIFORNIA THIS AFTERNOON. AS A RESULT,
WE COULD SEE SOME LIGHTNING OVER THE WATERS AND IMMEDIATE COAST.
SIMILAR INSTABILITY WILL ALSO BE PRESENT INLAND, AND WHILE THE LOW
LEVELS WILL PROBABLY BE TOO COOL TO PRODUCE THE SORT OF UPDRAFT
NEEDED FOR LIGHTNING TODAY, I DECIDED IT WAS WORTH MENTIONING OVER
THE CASCADES AND WEST SIDE.
THIS SYSTEM MOVES INLAND TONIGHT WITH SHOWERS DECREASING QUICKLY.
WE STAY IN COOL NW FLOW THROUGH WEDNESDAY THEN ANOTHER SYSTEM
BRINGS PRECIPITATION AND LOW SNOW LEVELS WEDNESDAY NIGHT INTO
THURSDAY. THIS SYSTEM IS WEAKER AND MUCH LESS WET, SO I DOUBT
HEADLINES WILL BE NECESSARY.
THE BIGGER EVENT LOOKS TO BE ON TAP FOR FRIDAY NIGHT INTO
SATURDAY. AS OF NOW, THIS SYSTEM LOOKS TO BE THE WETTEST, COLDEST
AND WINDIEST WE`VE SEEN IN SOME TIME. THE MOUNTAINS AND EAST SIDE
WILL ALMOST CERTAINLY GET SIGNIFICANT SNOW WITH THIS ONE. IT WILL
BE COLD ENOUGH FOR SNOW DOWN INTO THE LOWER VALLEYS ON THE BACK
SIDE, BUT AS ALWAYS IT WILL COME DOWN TO WHETHER THERE IS ENOUGH
PRECIPITATION LEFT WHEN THE COLD AIR ARRIVES. IT`S TOO EARLY TO
SAY FOR SURE, BUT EVERYONE SHOULD JUST BE AWARE THAT LOW ELEVATION
SNOW IS POSSIBLE FRIDAY NIGHT INTO SATURDAY. I WOULD EXPECT WINTER
AND POSSIBLY WIND HEADLINES WITH THIS SYSTEM.
YET ANOTHER SYSTEM IS SLATED FOR SUNDAY NIGHT INTO MONDAY AS THE
PROGRESSIVE NORTHWEST FLOW PATTERN CONTINUES. -WRIGHT
&&
.AVIATION...LOW PRESSURE SPINNING OFF OF THE PACIFIC NORTHWEST
COASTLINE IS SENDING COLDER AIR AND BANDS OF SHOWERS ACROSS THE
AREA. LATE TONIGHT THROUGH TUESDAY MORNING THE COLD CORE OF THIS
LOW WILL MOVE SOUTHEASTWARD THROUGH THE FORECAST AREA, MOVING
INLAND NEAR CAPE BLANCO AND THEN SOUTH-SOUTHEASTWARD INTO NORTHERN
CALIFORNIA.
A MIX OF MVFR AND VFR CEILINGS ALONG THE COAST IN SHOWERS AND
ACROSS THE EAST SIDE IN SNOW SHOWERS WILL LIKELY TURN TO MVFR ACROSS
THE WEST SIDE INLAND TO ABOUT ROSEBURG AND GRANTS PASS. MOUNTAINS
WILL BECOME OBSCURED IN CLOUDS AND SNOWFALL ACROSS MOST OF THE AREA,
THOUGH PRECIPITATION WILL BE SHOWERY, SO OBSCURATIONS WILL NOT BE
TOTAL. EXPECT MVFR TO LOCAL IFR TO DEVELOP OVER THE AREA FROM ABOUT
12Z TO 18Z TUESDAY AS THE CORE OF THE LOW PRESSURE SYSTEM MOVES
THROUGH AND SNOW LEVELS LOWER TO 2000 TO 3000 FEET, BUT LOCALLY
LOWER IN HEAVIER SHOWERS. ISOLATED THUNDERSTORMS ARE POSSIBLE
THROUGH TUESDAY DAY PRIMARILY ALONG AND NEAR THE COAST. AS THE LOW
MOVES SOUTHWARD TUESDAY AFTERNOON AND EVENING, SHOWERS WILL
PRIMARILY LINGER IN NORTHWEST UPSLOPE AREAS OF THE CASCADES AND
SISKIYOUS WITH MVFR CONDITIONS IN THE VALLEYS AND OBSCURATIONS IN
THOSE FAVORED UPSLOPE MOUNTAINOUS AREAS. OTHER AREAS WILL IMPROVE TO
VFR WITH AT LEAST PARTIAL CLEARING UNDER A LIGHT TO MODERATE NORTH
FLOW. BTL
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
ORZ031.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON ABOVE 2500
FEET FOR FOR ORZ024.
CA...WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
CAZ085.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON ABOVE 2500
FEET FOR FOR CAZ080.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON ABOVE 2500
FEET FOR FOR CAZ082-083.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL
2 AM PST FRIDAY FOR PZZ350-356-370-376.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM PST THIS AFTERNOON FOR
PZZ376.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 10 AM PST THIS MORNING FOR
PZZ370.
$$
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
947 AM PST TUE FEB 19 2013
.SHORT TERM DISCUSSION...
UPPER IMPULSE THAT WAS OVER 50N/135W YESTERDAY HAS DROPPED SWD TO
JUST NEAR THE SFO BAY AREA AS OF MID MORNING. SURFACE FRONT HAS ALSO
PUSHED INLAND WITH THE UP VALLEY PRESSURE GRADIENTS INCREASING TO
ALMOST 6 MBS FROM RDD TO SAC. WE DID A QUICK MORNING UPDATE TO
INCREASE THE WIND SPEEDS UNTIL FROPA THIS AFTERNOON. THE WINDS IN
THE N END OF THE VALLEY SHOULD DECREASE THIS AFTERNOON WHILE THERE
SHOULD BE WINDS PICKING UP THROUGH THE DELTA AND SRN SAC VLY.
PREFRONTAL PRECIP MAKING ITS WAY ACROSS THE VALLEY AND INTO THE
SIERNEV...DELTA AREA...AND SAC AREA AT PRESS TIME...IS FORECAST BY
THE RUC TO BECOME N-S ORIENTED OVER THE SIERNEV BY LATE AFTERNOON
AND INTO EVENING. SO SNOWFALL IS EXPECTED TO PICK UP OVER THE
SIERNEV...AND CONTINUE INTO EVENING...BEFORE BEGINNING TO DECREASE
AFTER 03Z-04Z OR SO. PRECIP WILL THEN TAPER OFF AND TURN SHOWERY
OVER THE VALLEY AND COASTAL RANGE BEHIND THE PREFRONTAL BAND. GIVEN
THIS TIMING...THE ADVISORY FOR THE SIERNEV LOOKS GOOD...WITH THE
ADVISORY FOR THE SHASTA AND COASTAL RANGE POSSIBLY EXPIRING WITH THE
AFTERNOON PACKAGE. SNOW PROFILERS AND SPOTTER REPORTS INDICATE THE
SNOW LEVEL IS ABOUT 2000 TO 2500 FT...WITH A FEW REPORTS DOWN TO
1500 FEET OVER THE COASTAL RANGE AS THE COLD MID LEVEL IMPULSE DROPS
SWD.
THE UPPER IMPULSE IS PROGGED TO DIG INTO THE BASE OF THE TROF OVER
THE WRN STATES WITH THE COLD POCKET MAINLY TRACKING ACROSS THE
COASTAL RANGE. CAN`T RULE OUT A THUNDERSTORM OR TWO...BUT LOOKING AT
THE BUFKIT FORECAST SOUNDINGS AND RAOB RECONSTRUCTION...WE NEED TO
WARM INTO THE LOW TO MID 50S TO GET SUFFICIENT CAPE OF A FEW HUNDRED
J/KG IN THE VALLEY...AND THE AIR MASS WILL BE COOLING TOO RAPIDLY
BEHIND THE FRONT. DURING THE AFTERNOON...THE SHEAR VALUES ALSO
LOOK TOO LOW FOR SEVERE WX. MANY OF THE SHOWERS THOUGH ARE LIKELY
TO CONTAIN SMALL HAIL/GRAUPEL.
MOISTURE IS LIMITED WITH THIS SYSTEM WITH VERY LOW PWS OF .40 TO .50
INCHES SO THE SHOWERS ARE QUITE SCATTERED UNDER THE IMPULSE AND
SHOULD REMAIN THAT WAY TODAY. BEST CLOUD ENHANCEMENT IS OVER THE
NERN QUARTER OF THE FORECAST AREA IN THE DIFFLUENT UPPER FLOW FROM
THE LOW. THIS IS LIKELY TO SHIFT SWD AND HIT THE 80/50 CORRIDOR AND
AREAS SWD THIS AFTERNOON AND EARLY EVENING. GIVEN THE UPPER
DIFFLUENCE OF THE 500 MBS FLOW AND OROGRAPHICS...ALBEIT FOR A
LIMITED TIME...THE HEAIEST QPF WILL BE OVER THE W SLOPE SIERNEV
WHERE WIDESPREAD QPFS OF .50 INCHES...LOCAL AMOUNTS UP TO AROUND .90
INCHES...AND ISOLATED 1.0 INCHES ARE FORECAST. 6 TO 10 INHCES OF
SNOW STILL LOOKS GOOD FOR THE SIERNEV. JHM
.PREVIOUS DISCUSSION...
SATIMG SHOWS DEEP TROUGH DIGGING SOUTHWARD TOWARD NORCAL EARLY
THIS MORNING WITH LOTS OF COLD-AIR CUMULUS AROUND THE LOW CENTER
OFFSHORE OREGON. BLENDED PW PRODUCT INDICATES LIMITED MOISTURE
WITH THE SYSTEM WITH PW OF ONLY 0.40 TO 0.50 INCHES. SCATTERED
LIGHT SNOW SHOWERS DEVELOPED DURING THE OVERNIGHT HOURS ACROSS THE
NORTHERN SIERRA AS THE UPPER FRONT AND ITS ASSOCIATED MID/UPPER
LEVEL JET PROVIDED ENOUGH LIFT...BUT ELSEWHERE SKIES HAVE BEEN
PARTLY CLOUDY WITH SOUTHERLY BREEZES PICKING UP IN THE SACRAMENTO
VALLEY.
TIMING STILL LOOKS GOOD FOR THE MAIN FRONTAL BAND OF SHOWERS TO
MOVE INLAND ACROSS NORCAL AROUND MIDDAY. RADAR SHOWS THE BAND
MOVING ONSHORE NW CA ATTM. THE STRONG DYNAMICS AND STRONG CAA
WILL LEAD TO SOME DECENT QPF WITH HIGHER THAN NORMAL SNOW-LIQUID
RATIOS. STEEPENING LAPSE RATES WILL LEAD TO CONVECTIVE ENHANCEMENT
OF SNOWFALL OVER THE REGION INTO THIS EVENING. LATEST HI-RES NAM
CROSS-SECTIONS INDICATE SNOWFALL WILL INCREASE ALONG I-80 OVER THE
NORTHERN SIERRA THIS MORNING AND CONTINUE INTO THIS EVENING.
SNOWFALL TOTALS OF 10 TO 12 INCHES WITH LOCALLY HIGHER AMOUNTS
WILL BE POSSIBLE ABOVE ABOUT 4000 FEET WITH LIGHTER ACCUMULATIONS
EXTENDING DOWN INTO THE FOOTHILL ELEVATIONS.
POTENTIAL FOR THUNDERSTORMS IS GOOD WITH THE UPPER LOW MOVING
THROUGH THIS AFTERNOON. 500 MB TEMPS FORECAST TO BE VERY COLD...
-30C TO -35C AS THE LOW MOVES OVERHEAD AROUND 00Z WED. LACK OF
SUSTAINED SURFACE HEATING DUE TO CLOUD COVER AND WEAK SHEAR
PARAMETERS DUE TO THE LIGHTER WINDS NEAR THE UPPER LOW CENTER WILL
LIMIT SEVERE POTENTIAL TODAY. HOWEVER...IT DOES LOOK LIKE LOW-
TOPPED STORMS THAT DEVELOP WILL BE ACCOMPANIED BY COPIOUS AMOUNTS
OF SMALL HAIL.
SYSTEM DROPS QUICKLY SOUTH OF THE REGION TONIGHT WITH SHOWERS
EXPECTED TO TAPER OFF FROM THE NORTH DURING THE EVENING. SHORT-
WAVE RIDGING WEDNESDAY IS EXPECTED TO PROVIDE A MOSTLY DRY DAY FOR
NORCAL THOUGH A FEW SHOWERS WILL BE POSSIBLE ACROSS THE HIGHER
TERRAIN. ANOTHER IMPULSE (WEAKER) IS FORECAST TO DROP SOUTHWARD
ALONG THE COAST WEDNESDAY NIGHT...THOUGH THERE IS MORE UNCERTAINTY
WITH THE TRACK OF THIS FEATURE...BRINGING WITH IT A CHANCE OF
SHOWERS. RIDGING OVER THE AREA THURSDAY AND FRIDAY ARE EXPECTED TO
LEAVE MOST OF THE AREA DRY...THOUGH MOISTURE SPILLING OVER THE
RIDGE MAY BRING SOME SHOWERS TO THE NORTHERN MOUNTAINS.
.EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)
EXTENDED MODELS STILL STRUGGLE TO CAPTURE DETAILS OF THE UNSETTLED
WEATHER PATTERN IN THE EXTENDED FORECAST. ANOTHER TROUGH SYSTEM
WILL DROP INTO THE PACIFIC NORTHWEST FRIDAY NIGHT INTO SATURDAY
AND THE BASE OF THE TROUGH WILL IMPACT NORCAL. THE ECMWF MODEL
SUGGESTS A DEEPER TROUGH EXTENDING TOWARDS SOCAL WHILE THE GFS AND
GEM SHOW THE BASE OF THE TROUGH BRUSHING NORCAL THEN DEEPENING
DEEPENING OVER THE GREAT BASIN. DRIER FOR MOST OF OUR CWA BY SUNDAY
AFTERNOON THOUGH LINGERING SHOWERS ARE POSSIBLE ACROSS FAR NORCAL
AND HIGHER TERRAIN. MODELS SUGGEST ANOTHER SYSTEM IMPACTING NORCAL
EITHER ON MONDAY OR TUESDAY. AGAIN MODEL CONSISTENCY HAS BEEN POOR
SO HAVE JUST KEPT SLIGHT CHANCE OF RAIN/SNOW DURING THIS TIME FRAME.
TEMPERATURES IN THE EXTENDED WILL GENERALLY BE NEAR TO SLIGHTLY
BELOW NORMAL FOR DAYTIME HIGHS: MID 50S TO LOW 60S IN THE VALLEY AND
30S TO 40S IN THE MOUNTAINS. MINIMUM TEMPERATURES ARE EXPECTED TO BE
BELOW NORMAL WITH LOWS IN THE MID 30S TO LOW 40S IN THE VALLEY AND
TEENS TO 20S IN THE MOUNTAINS.
&&
.AVIATION...
INCOMING WEATHER SYSTEM IS NOW BRINGING VCSH TO NORCAL VALLEYS AND
SNOW TO THE MOUNTAINS. -RA WITH MVFR CIGS AND BREEZY SOUTHERLY
WINDS GUSTING UP TO 30KTS CURRENTLY IMPACTING KRDD-KRBL VICINITY
WILL SPREAD SOUTHWARD THIS MORNING REACHING THE SAC METRO AREA BY
MID-MORNING AND THE KSCK-KMOD VCNTY AFTER 18Z. VALLEY
THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EVENING WHICH COULD
BRING LOCALIZED STRONG GUSTS, HEAVIER RAIN AND SMALL HAIL.
GENERALLY SOUTH TO SOUTHWEST FLOW TODAY BECOMING NORTHERLY TONIGHT
WITH IMPROVING CIGS AND DRIER WEATHER AFTER THE STORM SYSTEM
PASSES. CURRENT SNOW LEVELS AROUND 2500-3500 FT AND WILL CONTINUE
TO LOWER THROUGH TOMORROW TO AROUND 1500 FT. IFR/LIFR CONDITIONS
EXPECTED TODAY IN THE MOUNTAINS WITH SN AND WIND GUSTS UP TO 30
KTS. -DVC
&&
.STO WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 11 PM PST THIS EVENING ABOVE 2000
FEET FOR THE MOTHERLODE...NORTHEAST FOOTHILLS/SACRAMENTO
VALLEY...WEST SLOPE NORTHERN SIERRA NEVADA...WESTERN PLUMAS
COUNTY/LASSEN PARK.
WINTER WEATHER ADVISORY UNTIL 6 PM PST THIS EVENING ABOVE 2000
FEET FOR THE CLEAR LAKE/SOUTHERN LAKE COUNTY...MOUNTAINS
SOUTHWESTERN SHASTA COUNTY TO NORTHERN LAKE COUNTY...SHASTA LAKE
AREA / NORTHERN SHASTA COUNTY.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
413 PM EST TUE FEB 19 2013
.SYNOPSIS...
SCATTERED SNOW SHOWERS WILL BE POSSIBLE THIS EVENING THROUGH
WEDNESDAY AS AN UPPER LEVEL LOW PASSES NORTH OF THE AREA AND AN
ARCTIC AIR MASS PUSHES INTO THE AREA IN THE WAKE OF A COLD FRONT.
HIGH PRESSURE WILL MOVE ACROSS THE AREA THURSDAY BEFORE THE NEXT
FRONTAL SYSTEM BRINGS THE POTENTIAL FOR A WINTRY MIX THURSDAY NIGHT
INTO FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES AN CLOSED LOW CENTERED
OVER NORTHERN MICHIGAN WITH A BROAD CYCLONIC FLOW AROUND THIS
FEATURE EXTENDING INTO THE OHIO VALLEY. A VORT LOBE IS SWINGING
ACROSS WESTERN PA WITH THE TROUGH SOUTH OF THE LOW. IN
ADDITION...A 500MB VORT MAX IS PUSHING INTO NW OHIO. THIS FEATURE
IS PROVIDING FORCING FOR SCATTERED SNOW SHOWERS MOVING INTO THE
UPPER OHIO VALLEY. AT THE SURFACE...A COLD FRONT HAS PUSHED EAST
OF THE FORECAST AREA WITH CAA ONGOING IN A WEST-SOUTHWESTERLY
FLOW.
TONIGHT...GFS/NAM/ECMWF AGREE THAT THE CLOSED LOW WILL MOVE FROM
THE NORTHERN GREAT LAKES INTO UPSTATE NY OVERNIGHT. THE
AFOREMENTIONED VORT MAX WILL SHIFT INTO NRN PA OVERNIGHT WITH A
WESTERLY 1000-500MB MEAN LAYER WIND BECOMING MORE WEST-
NORTHWESTERLY BY 12Z WEDNESDAY. WITH THIS IN MIND...HAVE FORECAST
THE CHANCE OF SNOW SHOWERS ACROSS THE LOWLANDS WITH LIKELY POPS
ACROSS THE RIDGES AND I-80 CORRIDOR. HIRES MODELS (1KM ECM/HRW
WRF-NMM AND NAM NESTED) INDICATE SCATTERED SNOW SHOWERS WITH THE
SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY (SSE) PICKING UP ON
UPSLOPING COMPONENT WITH MORE NUMEROUS SNOW SHOWERS ACROSS THE
RIDGES. WITH THIS IN MIND...SNOWFALL FORECAST TONIGHT CONSISTS OF
1 TO 2 INCHES FOR THE EASTERN RIDGES AND THE I-80 CORRIDOR AND AN
INCH OR LESS ELSEWHERE. FOR TEMPS...A MAV/MET BLEND WAS USED WITH
LOWS RANGING FROM THE MID TO UPPER TEENS ACROSS THE AREA.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
A MODEL CONSENSUS INDICATES THAT THE UPPER LEVEL CYCLONE WILL PUSH
FURTHER EAST INTO THE NORTHEAST ON WEDNESDAY. THIS WILL ALLOW FOR THE
LOW-LEVEL FLOW TO VEER SLIGHTLY MORE...WITH A NORTHWESTERLY PREVAILING
WIND ON WEDNESDAY. GFS/NAM/CANADIAN INDICATE ANOTHER VORT MAX
CLIPPING LOCATIONS NORTHEAST OF PITTSBURGH DURING THE DAY...WITH
BETTER CHC FOR SNOW SHOWERS THERE. OTHERWISE...SNOW SHOWERS CHANCES
WILL BE DIMINISHING SOUTH AND WEST OF PITTSBURGH...WITH A DRY
FORECAST IN EASTERN OHIO BY 18Z. THUS...AN ADDITIONAL HALF OF AN
INCH TO AN INCH IS FORECAST NORTHEAST OF KPIT AND ACROSS THE RIDGES.
HIGHS ON WEDNESDAY WILL BE 10 TO 15 DEGREES BELOW NORMAL IN THE CORE
OF THE ARCTIC AIR MASS.
MOISTURE ASSOCIATED WITH THE UPPER LOW WILL FINALLY ADVECT NORTHEAST
OF THE AREA ON WEDNESDAY NIGHT AS A MID-LEVEL RIDGE AND HIGH
PRESSURE WILL BEGIN TO APPROACH FROM THE WEST. THIS WILL ALLOW FOR
ANY LINGERING SNOW SHOWERS TO COME TO AN END. A DRY FORECAST WILL
CONTINUE THROUGH THE DAY ON THURSDAY AS SURFACE HIGH PRESSURE
EXTENDS INTO THE AREA. TEMPS WILL BE AROUND 10 DEGREES BELOW NORMAL.
UNCERTAINTY AND MODEL INCONSISTENCY COMES INTO THE FORECAST FOR
THURSDAY NIGHT INTO FRIDAY. MODELS DO AGREE ON A STRONG UPPER LEVEL
VORTEX MOVING FROM THE CENTRAL PLAINS INTO THE UPPER MIDWEST DURING
THIS PERIOD. HOWEVER...SOLUTIONS DIFFER ON RESOLVING THE THERMAL
PROFILE OF A FRONTAL BOUNDARY PUSHING INTO THE OHIO VALLEY AHEAD OF
THE LOW. FORECAST CONSISTS OF A CANADIAN/ECMWF BLEND...WITH A TENTH
TO QUARTER OF AN INCH OF PRECIP REACHING THE AREA ON FRIDAY.
SOUNDINGS...1000-500MB/1000-850MB CRITICAL THICKNESS VALUES...AND
850MB TEMPS INDICATE THAT ONCE AGAIN THE UPPER OHIO VALLEY WILL BE
RIGHT ALONG THE LINE OF A WINTRY MIX OF PRECIPITATION. AT THIS
TIME...HAVE INCLUDED A WINTRY MIX OF SNOW...SLEET...AND FREEZING
RAIN ACROSS THE AREA WITH LIGHT ICE ACCUMULATION POSSIBLY LEADING
TO AN ADVISORY EVENT.
TEMPS THURSDAY NIGHT AND FRIDAY WILL BE A FEW DEGREES ABOVE
NORMAL...ALTHOUGH DEPENDING ON THE PLACEMENT OF THE BOUNDARY AND
STRENGTH OF WAA...THIS COULD IMPACT TEMP FORECAST FOR THIS
PERIOD.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A LOW PRESSURE CENTER MOVING SLOWLY THROUGH THE GREAT LAKES WILL
BRING A CHANCE OF RAIN AND SNOW SHOWERS FOR FRIDAY NIGHT INTO
SATURDAY NIGHT. HIGH PRESSURE WILL PROVIDE DRY WEATHER FOR SUNDAY
THROUGH MONDAY WITH TEMPERATURES A BIT ABOVE NORMAL. A COLD FRONT
PUSHING TOWARD THE DISTRICT WILL BRING A CHANCE OF SHOWERS MONDAY
NIGHT INTO TUESDAY.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
WIDESPREAD MVFR CEILINGS CAN BE EXPECTED THIS EVENING ALONG WITH A
FEW SNOW FLURRIES. FREQUENT SFC WND GUSTS OF 20 TO 25 KT ARE
ANTICIPATED THIS EVENING...BUT WILL DIMINISH AFTER MIDNIGHT. STRATOCU
CEILINGS WILL PERSIST TONIGHT ALONG WITH OCCASIONAL RESTRICTIONS IN
SNOW SHOWERS.
.OUTLOOK.../WEDNESDAY THROUGH SUNDAY/...
LINGERING RESTRICTIONS ARE ANTICIPATED THROUGH WEDNESDAY IN THE
COLD NORTHWEST FLOW BEHIND THE FRONT. VFR IS ANTICIPATED WITH THU
HIGH PRES. RESTRICTIONS ARE POSSIBLE AGAIN ON FRIDAY AND SATURDAY
WITH THE CROSSING OF ANOTHER TROF. VFR WEATHER CAN BE EXPECTED
SUNDAY WITH HIGH PRESSURE.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
340 PM EST TUE FEB 19 2013
.SYNOPSIS...
A COLD FRONT AND ASSOCIATED PRECIPITATION WILL MOVE OFF THE MIDDLE
ATLANTIC COAST LATER THIS EVENING. GUSTY WINDS WILL FOLLOW WEDNESDAY
INTO WEDNESDAY NIGHT FOLLOWED BY HIGH PRESSURE BRIEFLY SETTLING OVER
THE REGION ON THURSDAY. A WAVE OF LOW PRESSURE WILL BRING A WINTRY
MIX TO THE MIDDLE ATLANTIC ON FRIDAY INTO THE FIRST PART OF THE
WEEKEND.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
MAIN AREA OF LIFT/RAIN WILL PROGRESS EASTWARD THROUGH CENTRAL AND
SOUTHERN MARYLAND THROUGH LATE AFTERNOON. COLD FRONT WAS APPROACHING
THE POTOMAC HIGHLANDS AT 19Z. THERE IS A THIN BAND OF PRECIPITATION
AHEAD OF IT THAT WILL AFFECT THE HIGHLANDS. HRRR AND WRF-ARW SUGGEST
THIS THIN BAND HOLDS TOGETHER EAST TOWARD THE BAY /AS RAIN/ AS THE
FRONT MOVES THROUGH. THUS HAVE CONTINUED POPS UNTIL THE FROPA.
COLD FRONTAL PASSAGE LOOKS TO OCCUR JUST BEFORE 00Z ACROSS THE
INTERSTATE 95 CORRIDOR. WINDS WILL SHIFT FROM SOUTH TO WEST...AND
MAY BECOME GUSTY. CLOUDS WILL HANG TOUGH PRIOR TO THE FROPA...BUT
EXPECT CLEARING TO OCCUR LATER THIS EVENING BEHIND THE FRONT.
UPSLOPE SNOW SHOWERS ARE EXPECTED TONIGHT BEHIND THE FRONT AS
WELL...BUT ACCUMULATIONS ON THE WESTERN SLOPES ARE EXPECTED TO BE ON
THE ORDER OF 1 TO 2 INCHES WHICH IS BELOW WINTER WEATHER ADVISORY
CRITERIA.
ENTIRE CWA WILL BE BLUSTERY OVERNIGHT...WITH THE RIDGES ON THE WINDY
SIDE. COULD GET CLOSE TO WIND ADVISORY CRITERIA ON THE RIDGE TOPS.
WILL CONTINUE HWO MENTION FOR 40 MPH GUSTS.
WEDNESDAY WILL BE A WINDY DAY ACROSS THE CWA...WITH GUSTS OF 35 MPH
AT TIMES AND HIGHER OVER THE RIDGE TOPS. EXPECT THE SUN TO RETURN
BUT DESPITE A DOWNSLOPING FLOW CHILLY AIR ALOFT WILL LIKELY BRING AT
LEAST SOME SCATTERED CLOUDS FOR THE AFTERNOON.
MAXIMA WILL BE COLDER AS WELL...10 OR MORE DEGREES BELOW CLIMO. THIS
IS CAPTURED WELL BY BIAS CORRECTED MAV/MET GUIDANCE.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
WINDS WILL GRADUALLY DIMINISH WEDNESDAY NIGHT AS THE GRADIENT
RELAXES BETWEEN THE DEPARTING LOW AND BUILDING RIDGE. COLD
TEMPERATURES WILL FOLLOW FOR WEDNESDAY NIGHT WITH LOWS IN THE
LOWER TO MIDDLE 20S MOST SECTIONS EXCEPT LOWER TO MIDDLE TEENS
FURTHER NORTH AND WEST. BELOW NORMAL TEMPERATURES ARE EXPECTED
THURSDAY AFTERNOON AS READINGS STRUGGLE TO REACH THE 40 DEGREE
MARK IN MOST LOCALES.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE NEXT WEATHER MAKER WILL CROSS THE FOUR CORNERS REGION
WEDNESDAY NIGHT INTO THURSDAY WITH LOW PRESSURE EJECTING NORTHEAST
INTO THE GREAT LAKES BY FRIDAY. PRECIPITATION ASSOCIATED WITH THIS
FEATURE WILL DEVELOP OVER WESTERN SECTIONS EARLY FRIDAY MORNING
AND SPREAD EAST ACROSS THE REMAINDER OF THE FORECAST AREA FRIDAY
AFTERNOON. THE PRECIPITATION ASSOCIATED WITH THIS SYSTEM APPEARS TO
BE LIGHT AND DRIVEN BY WARM AIR ADVECTION PROCESSES ATOP A SHALLOW
COLD AIRMASS. OF CONCERN...MODELS CONTINUE TO SHOW A PERSISTENT
COLD AIR DAMMING WEDGE WITH A 1025-1030MB HIGH TO THE NORTH FOR
THE START OF THE EVENT. INITIALLY...PRECIPITATION WOULD FALL IN
THE FORM OF SNOW WITH SOME SLEET POSSIBLE. IT GETS A BIT
CHALLENGING LATER FRIDAY MORNING AND AFTERNOON AS WARM ADVECTION
CONTINUES AND THE COLD AIR BEGINS TO GET SCOURED TO THE NORTH.
MODELS TYPICALLY DO NOT HANDLE TIMING OF THIS SCENARIO TOO WELL
AND AM CONCERNED THAT MORE FROZEN PRECIPITATION COULD HANG AROUND
LONGER. EVENTUALLY THE WARMER AIR IS EXPECTED TO WIN OUT EAST OF THE
BLUE RIDGE WITH PRECIPITATION CHANGING TO RAIN FOR THE METRO AREAS
BUT COULD REMAIN SLEET/FREEZING RAIN WEST OF THE BLUE RIDGE AND OVER
NORTHERN MARYLAND NEAR THE MASON DIXON LINE. HAVE TRENDED
TEMPERATURES DOWN A COUPLE DEGREES FOR HIGHS. WILL HAVE TO WATCH
THIS SCENARIO CLOSELY.
PRECIPITATION COULD HOLD IN PLACE INTO SATURDAY OVER THE WESTERN
FIVE IN UPSLOPE REGIME AND OVER SOUTHERN AND CENTRAL MARYLAND AS
LOW PRESSURE DEVELOPS OVER THE CAROLINAS AND MOVES NORTHEAST AWAY
FROM THE FORECAST AREA LATER SATURDAY. 12Z ECMWF NOW TRACKS THIS
LOW A BIT FURTHER EAST WHICH PRESENTS LESS OF A THREAT TO OUR AREA.
WILL STILL HOLD ONTO CHANCE POPS FOR RAIN SATURDAY. TRANQUIL WEATHER
IS PROGGED TO RETURN TO THE REGION ON SUNDAY WITH A POSSIBLE
MODERATION IN TEMPERATURES IF LONGER RANGE PROGS BODE WELL FOR EARLY
NEXT WEEK.
&&
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
MVFR CONDITIONS...MAINLY FROM CIGS WITHIN RAIN...ARE EXPECTED TO
LINGER INTO LATE AFTERNOON ACROSS THE DC-BALT HUBS. CONDITIONS
SHOULD IMPROVE TO VFR THEREAFTER...PARTICULARLY WITH A FRONTAL
PASSAGE AROUND 23Z. THIS WILL INITIATE A WIND SHIFT FROM SOUTH TO
WEST. WINDS MAY BE GUSTY WITH THE FROPA AND BEHIND IT. GUSTY WINDS
EXPECTED TO CONTINUE INTO WEDNESDAY...BEING THE PRIMARY AVIATION
IMPACT.
GUSTY WINDS WILL SUBSIDE WEDNESDAY NIGHT BUT WILL BE BREEZY AGAIN
THURSDAY WITH SPEEDS GENERALLY IN THE 10 TO 15 KT RANGE WITH GUSTS
TO 20 KTS. VFR EXPECTED THURSDAY. WINTRY PRECIPITATION WILL BE
POSSIBLE AT THE TERMINALS FRIDAY INTO FRIDAY NIGHT WITH SUB-VFR
CONDITIONS POSSIBLE. RAIN POSSIBLE SATURDAY INTO SATURDAY NIGHT
BEFORE VFR RETURNS FOR SUNDAY.
&&
.MARINE...
COLD FRONT WILL MOVE ACROSS THE WATERS EARLY THIS EVENING. HAVE BEEN
EXPERIENCING MARGINAL SMALL CRAFT ADVISORY CONDITIONS IN SOUTHERLY
FLOW THIS AFTERNOON. WITH FRONTAL PASSAGE...WINDS WILL SHIFT TO THE
WEST AND BECOME MORE GUSTY /25 KT/. WINDS ON WEDNESDAY ARE THEN
EXPECTED TO TURN TO THE NORTHWEST. MODELS TEND TO UNDERFORECAST
SPEEDS IN NORTHWEST FLOW WITH ADVECTION...THEREFORE HAVE GONE ABOVE
GUIDANCE WHICH PLACES THE BAY/LOWER TIDAL POTOMAC INTO LOW END
GALES.
GUSTY WINDS WILL DIMINISH WEDNESDAY NIGHT BUT SMALL CRAFT
CONDITIONS MAY BE POSSIBLE AGAIN ON THURSDAY. WINTRY PRECIPITATION
COULD DEVELOP OVER THE WATERS REDUCING VISIBILITIES DURING FRIDAY
WITH RAIN EXPECTED FRIDAY NIGHT INTO SATURDAY. SMALL CRAFT CONDITIONS
MAY OCCUR OVER THE WEEKEND AS A COASTAL LOW MOVES BY TO THE
NORTHEAST.
&&
.TIDES/COASTAL FLOODING...
COLD FRONT MOVES THROUGH EARLY THIS EVENING. SOUTHERLY WINDS WILL
SHIFT TO THE WEST TONIGHT...THEN LIKELY TO THE NORTHWEST FOR
WEDNESDAY/WEDNESDAY NIGHT. EXPECT WATER LEVELS TO DRAMATICALLY DROP
TONIGHT...PERHAPS TO 1 TO 2 FEET BELOW ASTRONOMICAL PREDICTIONS FOR
WEDNESDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EST WEDNESDAY FOR
ANZ530>534- 537>543.
GALE WARNING FROM 2 PM WEDNESDAY TO MIDNIGHT EST WEDNESDAY
NIGHT FOR ANZ530>534-537>543.
SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST WEDNESDAY NIGHT FOR
ANZ535-536.
&&
$$
SYNOPSIS...KRW
NEAR TERM...BPP
SHORT TERM...KRW
LONG TERM...KRW
AVIATION...BPP/KRW
MARINE...BPP/KRW
TIDES/COASTAL FLOODING...BPP
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
431 PM EST TUE FEB 19 2013
.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 18Z TAFS THROUGH 18Z WEDNESDAY)
ISSUED AT 430 PM EST TUE FEB 19 2013
CMX...EXPECT PREDOMINANT VLIFR CONDITIONS TODAY AS VERY STRONG NNW
WINDS COMBINE WITH LAKE ENHANCED SNOW TO PRODUCE NEAR BLIZZARD
CONDITIONS AT TIMES FOR MUCH OF TODAY. THE WINDS MAY DIMINISH ENOUGH
TOWARD THIS EVENING FOR SOME IMPROVEMENT WITH LIFR/IFR CONDITIONS
AND SHOULD IMPROVE TO MVFR ON WEDNESDAY AS DRIER AIR MOVES IN FM
NORTH OF THE LAKE.
IWD...SN/BLSN WILL ALSO KEEP MAINLY IFR/LIFR CONDITIONS AT IWD.
THERE SHOULD BE IMPROVEMENT TO MVFR BY WEDNESDAY MORNING AS THE
WINDS SLOWLY DIMINISH ONCE THE LO SHIFTS FARTHER TO THE E.
SAW...EXPECT PREDOMINANT IFR CONDITIONS THIS AFTERNOON IN SNOW AND
BLOWING SNOW WITH GUSTY NW WINDS. AS THE LOW PULLS OFF TO THE E
TONIGHT...AND WINDS DIE DOWN SOME EXPECT IMPROVEMENT TO MVFR THIS
EVENING WHICH WILL CONTINUE INTO WEDNESDAY.
&&
.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 MIZ002-004-009-013-084.
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...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1259 PM EST TUE FEB 19 2013
.AVIATION...
//DISCUSSION...
GUSTY WEST WINDS WILL CONTINUE THROUGH THE AFTERNOON AND EARLY
EVENING...WITH GUSTS UP TO 35 KNOTS. GUSTS WILL SUBSIDE OVERNIGHT AS
THE MIXED LAYER DECREASES...BUT SUSTAINED WINDS WILL STILL STAY UP
FROM THE WEST AT AT 14 TO 20 KNOTS...BEFORE TURNING NORTHWEST
TOWARDS SUNRISE. SNOW SHOWERS WILL ALSO CONTINUE TO STREAM OVER THE
AREA AS MOISTURE WRAPS INTO THE AREA ON THE BACKSIDE OF A LOW
PRESSURE SYSTEM THAT PUSHED ACROSS NORTHERN MICHIGAN EARLIER
TODAY...WITH SOME ENHANCEMENT FROM FLOW OVER LAKE MICHIGAN. MVFR
VISIBILITIES/CEILINGS WILL PREVAIL THROUGH THE AFTERNOON...WITH DIPS
INTO IFR LIKELY IN THE HEAVIER BURSTS OF SNOW. THESE CONDITIONS ARE
SIMILAR TO WHAT WE HAVE SEEN ACROSS THE AREA OVER THE PAST SEVERAL
HOURS...ALTHOUGH CEILINGS HAVE RISEN A LITTLE BIT AS MIXING
INCREASES. SHOWERS WILL DECREASE IN COVERAGE AND INTENSITY THIS
EVENING...AND BECOME MORE FOCUSED FROM PTK SOUTHWARD OVERNIGHT AS
FLOW OFF LAKE MICHIGAN TURNS MORE TO THE NORTHWEST.
FOR DTW...MVFR CEILINGS/VISIBILITIES WILL PREVAIL THROUGH THE
AFTERNOON...THOUGH BRIEF PERIODS OF VFR WILL BE POSSIBLE IN BETWEEN
SNOW SHOWERS. SNOW SHOWERS WILL CONTINUE OVERNIGHT...BUT WILL BECOME
LESS WIDESPREAD AS SNOW BECOMES MORE LAKE EFFECT DOMINATED AND FLOW
OFF LAKE MICHIGAN TURNS NORTHWEST.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET TODAY THROUGH TONIGHT.
* HIGH CONFIDENCE IN SNOW AS PRECIPITATION TYPE TODAY AND TONIGHT.
&&
.PREV DISCUSSION...ISSUED 1134 AM EST TUE FEB 19 2013
UPDATE...
WINDS HAVE BEEN FALLING A LITTLE SHY OF ADVISORY CRITERIA...ASIDE
FROM AN INITIAL BURST WITH 40 MPH GUSTS THAT ACCOMPANIED THE
PASSAGE OF THE COLD FRONT EARLY THIS MORNING. LOOKING AT FORECAST
SOUNDINGS FROM 12Z MODEL DATA...IT STILL APPEARS POSSIBLE FOR GUSTS
TO ATTAIN SPEEDS OF 40 TO 45 MPH AS THE MIXED LAYER DEEPENS THIS
AFTERNOON. WILL THEREFORE KEEP THE WIND ADVISORY INTACT...AT LEAST
INTO THE MID-AFTERNOON BEFORE REASSESSING.
SNOW HAS ALSO BEEN SPREADING INTO THE AREA ON THE BACKSIDE OF THE
SYSTEM...AS MOISTURE DEPTH DEEPENS ONCE AGAIN BEHIND THE MID-LEVEL
DRY SLOT AND AS PVA INCREASES AHEAD OF THE UPPER LOW. LAKE
ENHANCEMENT WILL ALSO CONTRIBUTE BUT STILL EXPECT HEAVIER SNOW TO
STAY TO OUR WEST. ACCUMULATIONS BETWEEN 0.5 AND 2 INCHES STILL
LOOK GOOD FOR THIS SIDE OF THE STATE. BIGGEST CONCERN WILL BE
REDUCED VISIBILITIES IN HEAVIER BURSTS OF SNOW.
PREV DISCUSSION...ISSUED 347 AM EST TUE FEB 19 2013
SHORT TERM... TODAY AND TONIGHT
MILD AND WET CONDITIONS THROUGHOUT SE MICHIGAN DURING THE EARLY
MORNING WILL BE KICKED OUT OF THE AREA BY A STRONG COLD FRONT
PASSING THROUGH AROUND SUNRISE. THE MAIN CONCERN WITH THIS FRONT
WILL BE PEAK WIND GUSTS REACHING 45 MPH ADVISORY CRITERIA IN THE
STRONG WESTERLY FLOW BEHIND IT, BUT THE COMBINATION OF FALLING
TEMPERATURES AND SNOW SHOWERS WILL ALSO ADD A LAYER OF HARSHNESS TO
CONDITIONS THROUGH THE DAY. EXPECT TEMPERATURES TO FALL TOWARD THE
MID AND UPPER 20S BY LATE MORNING, STRUGGLE TO REMAIN IN THE 20S
DURING THE AFTERNOON WITH SINGLE DIGIT WIND CHILL, AND THEN GIVE WAY
TO LOWS WELL DOWN INTO THE TEENS TONIGHT WITH WIND CHILL ABOUT 5
BELOW AFTER MIDNIGHT.
UPSTREAM OBSERVATIONS, ALONG WITH MODEL ISALLOBARIC FIELDS, INDICATE
THE STRONGEST WIND GUSTS OF 40 TO 50 KNOTS OVER CENTRAL INDIANA
OCCURRED WITHIN THE STEEPEST ISALLOBARIC GRADIENT ASSOCIATED WITH A
PEAK 3 HOUR PRESSURE RISE STARTING OFF CLOSE TO 10 MB. THIS PRESSURE
RISE CENTER IS SHOWN TO WEAKEN FROM NEARLY 10 MB TO 3-4 MB IN THE
NAM12 AND HIGH RES RAP MODELS AS THE FRONT MOVES THROUGH WESTERN
LOWER MICHIGAN AND THE REST OF INDIANA AND OHIO. THIS WEAKENING OF
THE ISALLOBARIC COMPONENT OF DYNAMIC FORCING WILL LIKELY RESULT IN A
SHORTER DURATION OF PEAK GUSTS AROUND 45 MPH IN OUR AREA ALONG AND
IMMEDIATELY POST FRONT. AFTER THAT, EXPECT A FEW HOURS OF WIND GUSTS
LESS THAN 40 MPH UNTIL COLD ADVECTION AND SYSTEM RELATIVE ISENTROPIC
DESCENT RAMPS UP LEADING TO STEEPENING LAPSE RATES IN A DEEPENING
BOUNDARY LAYER. DOWNWARD MOMENTUM TRANSPORT WILL THEN BE SUFFICIENT
FOR GUSTS TO REACH 45 MPH AGAIN BY LATE MORNING THROUGH THE
AFTERNOON. GUSTS WILL DIMINISH BY TONIGHT BUT WILL REMAIN IN THE 30
MPH RANGE AS THE BOUNDARY LAYER REMAINS WELL MIXED AFTER SUNSET.
AFTER THE DRY SLOT KEEPS SNOW AT BAY DURING THE MORNING, AN
EXPANSIVE AREA OF MID LEVEL MOISTURE WRAPPING AROUND THE WESTERN
FLANK OF THE LOW WILL DRIVE THE PATTERN OF SNOW DURING THE AFTERNOON
THROUGH TONIGHT. EARLY MORNING RADAR COMPOSITES SHOW THIS COMING
TOGETHER OVER THE UPPER MIDWEST AT PRESS TIME ADDING CONFIDENCE TO
THE EXPECTATION OF A HIGH POP/LOW ACCUMULATION SCENARIO. THIS
MOISTURE WILL SEED ENHANCEMENT FROM LAKE MICHIGAN AS INSTABILITY
INCREASES INTO THE 15-20C RANGE FOR LAKE TO 850 MB DELTA-T. THE MAIN
LIMITING FACTOR WILL BE THE STRONG WIND SPEED AND STEADY VEERING
TREND THAT WILL PREVENT ANY DOMINANT BAND FORMATION. PLAN TO FAVOR
THE TRI CITIES AND THUMB WITH CATEGORICAL POPS DURING THE AFTERNOON
AND LIKELY INTO THE THE EVENING WITH 1 TO 2 INCHES OF ACCUMULATION
BEFORE THE WIND SHIFT TOWARD THE NORTHWEST FAVORS AREAS SOUTH OF
INTERSTATE 69 TOWARD SUNRISE WEDNESDAY.
LONG TERM...
ALTHOUGH THE 500 MB LOW/MID LEVEL COLD POOL WILL BE MOVING INTO NEW
ENGLAND ON WEDNESDAY...A SHALLOW (SFC-925 MB) BACK DOOR COLD FRONT
WILL ATTEMPT TO MAKE INROADS INTO SOUTHERN LOWER MICHIGAN.
925 MB TEMPS OF -16 TO -17 C FORECASTED TO WORK THROUGH THE THUMB
REGION...WITH LOW LEVEL FLOW JUST SLIGHTLY WEST OF DUE NORTH.
SO...REASONABLE EXPECTATION SOME LAKE EFFECT SNOW SHOWER ACTIVITY
WILL BRUSH THE SHORELINE...BUT SHALLOW NATURE OF THE ACTIVITY
(MODERATING 850 MB TEMPS) SHOULD PREVENT ACTIVITY FROM GETTING OUT
OF HAND. 1042 MB HIGH OVER ONTARIO WILL NOSE INTO SOUTHEAST MICHIGAN
ON THURSDAY...AS AMPLIFIED UPPER LEVEL RIDGE MOVES OVER THE WESTERN
GREAT LAKES. POTENT UPPER WAVE JUST OFF THE PACIFIC NORTHWEST COAST
EARLY THIS MORNING STILL PROGGED TO ROTATE THROUGH THE FOUR CORNERS
REGION LATE WEDNESDAY...BUT TRACKING JUST A TOUCH FARTHER
EAST...OVER/NEAR SIOUX FALLS SOUTH DAKOTA THURSDAY NIGHT (PER 00Z
GFS/EURO). DRAMATIC WEST-EAST SHEARING OF THE UPPER LEVEL
CIRCULATION WILL OCCUR...BUT STILL A PERIOD OF LARGE SCALE ASCENT/PV
ADVECTION FRIDAY MORNING TO OCCUR OVER SOUTHEAST MICHIGAN. THE BULK
OF THE LIFT WILL BE USED UP JUST TO SATURATE THE LOW LEVELS...AS THE
PREVIOUSLY MENTIONED HIGH OVER ONTARIO LEADS TO EASTERLY DRY LOW
LEVEL FLOW PERSISTING INTO FRIDAY. 00Z GFS NOT EVEN GIVING US A
TENTH OF AN INCH OF QPF...AS DEEPER MOISTURE SEEN IN THE 850-700
MB/PW FIELDS SKIRTS JUST TO THE SOUTHEAST OF THE CWA. STILL...DECENT
SHOT OF MOISTURE ADVECTION...AND PREFERENCE IS WITH THE STRONGER
CANADIAN/EURO WHICH MAINTAINS THE 500 MB LOW OVER MINNESOTA INTO THE
FIRST HALF OF THE WEEKEND. QPF FROM THOSE MODELS SUPPORTS A SOLID 1
TO TWO INCHES OF SNOW ON FRIDAY...WITH RELATIVELY LOW SNOW TO LIQUID
RATIOS...AS ZERO OR SLIGHTLY BETTER 850 MB TEMPS SEEN REACHING THE
OHIO BORDER.
THE MODEST MID LEVEL COLD POOL OVER MINNESOTA WILL BREAK OFF TO THE
EAST FOR THE WEEKEND...KEEPING TEMPERATURES IN CHECK...AS 850 MB
TEMPS LOOK TO BE HOVERING AROUND -10 C...AND WITH LIMITED
SUNSHINE...MAXES EXPECTED TO REMAIN GENERALLY BELOW 40 DEGREES.
ALTHOUGH...WE WILL HAVE THE DRY SLOT WORKING THROUGH SATURDAY
MORNING...WHICH COULD BE THE DAY WE SNEAK UP TO 40 DEGREES.
MARINE...
DEEP LOW PRESSURE MOVING THROUGH THE STRAITS WILL PULL A STRONG COLD
FRONT THROUGH LAKE HURON AND LOWER MICHIGAN EARLY IN THE MORNING.
WESTERLY GALES WILL DEVELOP AFTER THE FRONTAL PASSAGE AND THEN
PERSIST TONIGHT THROUGH WEDNESDAY WHILE VEERING TO NORTHWEST OVER
THE OPEN WATERS OF LAKE HURON. POLAR AIR SURGING BACK INTO THE
REGION WILL CHANGE RAIN BACK TO SNOW AND ALSO LEAD TO A SUBSTANTIAL
FREEZING SPRAY HAZARD OVER THE OPEN WATERS TONIGHT THROUGH
WEDNESDAY. THE STRONG WINDS AND RESULTING LARGE WAVES WILL COMBINE
WITH NEAR IDEAL WATER TEMPERATURE FOR WIDESPREAD FREEZING SPRAY TO
BECOME HEAVY. MARINE CONDITIONS WILL THEN IMPROVE CONSIDERABLY BY
THURSDAY AS HIGH PRESSURE SETTLES OVER THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055-MIZ060-
MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075-MIZ076-MIZ082-
MIZ083...UNTIL 7 PM TUESDAY.
LAKE HURON...
GALE WARNING...LHZ361-LHZ362-LHZ363...UNTIL 7 PM WEDNESDAY.
HEAVY FREEZING SPRAY WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-
LHZ464...FROM 7 PM TUESDAY TO 7 PM WEDNESDAY.
GALE WARNING...LHZ421-LHZ422-LHZ441-LHZ442-LHZ443-LHZ462-LHZ463-
LHZ464...UNTIL MIDNIGHT WEDNESDAY.
LAKE ST CLAIR...
GALE WARNING...UNTIL MIDNIGHT WEDNESDAY.
MI WATERS OF LAKE ERIE...
GALE WARNING...UNTIL MIDNIGHT WEDNESDAY.
&&
$$
AVIATION.....HLO
UPDATE.......HLO
SHORT TERM...BT
LONG TERM....SF
MARINE.......BT
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1134 AM EST TUE FEB 19 2013
.UPDATE...
WINDS HAVE BEEN FALLING A LITTLE SHY OF ADVISORY CRITERIA...ASIDE
FROM AN INITIAL BURST WITH 40 MPH GUSTS THAT ACCOMPANIED THE
PASSAGE OF THE COLD FRONT EARLY THIS MORNING. LOOKING AT FORECAST
SOUNDINGS FROM 12Z MODEL DATA...IT STILL APPEARS POSSIBLE FOR GUSTS
TO ATTAIN SPEEDS OF 40 TO 45 MPH AS THE MIXED LAYER DEEPENS THIS
AFTERNOON. WILL THEREFORE KEEP THE WIND ADVISORY INTACT...AT LEAST
INTO THE MID-AFTERNOON BEFORE REASSESSING.
SNOW HAS ALSO BEEN SPREADING INTO THE AREA ON THE BACKSIDE OF THE
SYSTEM...AS MOISTURE DEPTH DEEPENS ONCE AGAIN BEHIND THE MID-LEVEL
DRY SLOT AND AS PVA INCREASES AHEAD OF THE UPPER LOW. LAKE
ENHANCEMENT WILL ALSO CONTRIBUTE BUT STILL EXPECT HEAVIER SNOW TO
STAY TO OUR WEST. ACCUMULATIONS BETWEEN 0.5 AND 2 INCHES STILL
LOOK GOOD FOR THIS SIDE OF THE STATE. BIGGEST CONCERN WILL BE
REDUCED VISIBILITIES IN HEAVIER BURSTS OF SNOW.
&&
.AVIATION...ISSUED 733 AM EST TUE FEB 19 2013
//DISCUSSION...
STRONG SOUTHWEST WIND AND FALLING TEMPERATURE WILL BE THE MAIN
AVIATION CONCERN DURING THE MORNING AS MID LEVEL DRY AIR INITIALLY
KEEPS SNOW SHOWERS AT A MINIMUM. CEILING WILL REMAIN NO BETTER
THAN MVFR, HOWEVER, AND THEN SNOW WILL INCREASE IN COVERAGE AND
INTENSITY DURING THE LATE MORNING AND THROUGH THE AFTERNOON, ALL
WHILE WESTERLY WIND GUSTS INCREASE TO ABOUT 35 KNOTS. IFR
VISIBILITY RESTRICTION IN SNOW AND BLOWING SNOW IS LIKELY AT FNT
AND MBS INTO THE EARLY EVENING BEFORE BOTH THE SNOW AND THE WIND
GUSTS DIMINISH THROUGH TONIGHT. MVFR CEILING AND SOME FLURRIES OFF
THE SOUTH END OF LAKE MICHIGAN WILL BE POSSIBLE IN THE DTW AREA
TOWARD SUNRISE WEDNESDAY.
FOR DTW... A POCKET OF SNOW IN THE CHICAGO AREA AT PRESS TIME WILL
MOVE THROUGH SOUTHERN MICHIGAN DURING THE MORNING AND INTO THE DTW
AREA BY NOON WHILE WESTERLY WIND GUSTS CONTINUE IN THE 30 TO 35 KNOT
RANGE. EXPECT ACCUMULATION TO BE LESS THAN AN INCH DURING THE
AFTERNOON WITH THIS ACTIVITY AS TEMPERATURES FALL IN THE MID AND
UPPER 20S.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET TODAY THROUGH TONIGHT.
* HIGH CONFIDENCE IN SNOW AS PRECIPITATION TYPE TODAY AND TONIGHT.
&&
.PREV DISCUSSION...ISSUED 347 AM EST TUE FEB 19 2013
SHORT TERM... TODAY AND TONIGHT
MILD AND WET CONDITIONS THROUGHOUT SE MICHIGAN DURING THE EARLY
MORNING WILL BE KICKED OUT OF THE AREA BY A STRONG COLD FRONT
PASSING THROUGH AROUND SUNRISE. THE MAIN CONCERN WITH THIS FRONT
WILL BE PEAK WIND GUSTS REACHING 45 MPH ADVISORY CRITERIA IN THE
STRONG WESTERLY FLOW BEHIND IT, BUT THE COMBINATION OF FALLING
TEMPERATURES AND SNOW SHOWERS WILL ALSO ADD A LAYER OF HARSHNESS TO
CONDITIONS THROUGH THE DAY. EXPECT TEMPERATURES TO FALL TOWARD THE
MID AND UPPER 20S BY LATE MORNING, STRUGGLE TO REMAIN IN THE 20S
DURING THE AFTERNOON WITH SINGLE DIGIT WIND CHILL, AND THEN GIVE WAY
TO LOWS WELL DOWN INTO THE TEENS TONIGHT WITH WIND CHILL ABOUT 5
BELOW AFTER MIDNIGHT.
UPSTREAM OBSERVATIONS, ALONG WITH MODEL ISALLOBARIC FIELDS, INDICATE
THE STRONGEST WIND GUSTS OF 40 TO 50 KNOTS OVER CENTRAL INDIANA
OCCURRED WITHIN THE STEEPEST ISALLOBARIC GRADIENT ASSOCIATED WITH A
PEAK 3 HOUR PRESSURE RISE STARTING OFF CLOSE TO 10 MB. THIS PRESSURE
RISE CENTER IS SHOWN TO WEAKEN FROM NEARLY 10 MB TO 3-4 MB IN THE
NAM12 AND HIGH RES RAP MODELS AS THE FRONT MOVES THROUGH WESTERN
LOWER MICHIGAN AND THE REST OF INDIANA AND OHIO. THIS WEAKENING OF
THE ISALLOBARIC COMPONENT OF DYNAMIC FORCING WILL LIKELY RESULT IN A
SHORTER DURATION OF PEAK GUSTS AROUND 45 MPH IN OUR AREA ALONG AND
IMMEDIATELY POST FRONT. AFTER THAT, EXPECT A FEW HOURS OF WIND GUSTS
LESS THAN 40 MPH UNTIL COLD ADVECTION AND SYSTEM RELATIVE ISENTROPIC
DESCENT RAMPS UP LEADING TO STEEPENING LAPSE RATES IN A DEEPENING
BOUNDARY LAYER. DOWNWARD MOMENTUM TRANSPORT WILL THEN BE SUFFICIENT
FOR GUSTS TO REACH 45 MPH AGAIN BY LATE MORNING THROUGH THE
AFTERNOON. GUSTS WILL DIMINISH BY TONIGHT BUT WILL REMAIN IN THE 30
MPH RANGE AS THE BOUNDARY LAYER REMAINS WELL MIXED AFTER SUNSET.
AFTER THE DRY SLOT KEEPS SNOW AT BAY DURING THE MORNING, AN
EXPANSIVE AREA OF MID LEVEL MOISTURE WRAPPING AROUND THE WESTERN
FLANK OF THE LOW WILL DRIVE THE PATTERN OF SNOW DURING THE AFTERNOON
THROUGH TONIGHT. EARLY MORNING RADAR COMPOSITES SHOW THIS COMING
TOGETHER OVER THE UPPER MIDWEST AT PRESS TIME ADDING CONFIDENCE TO
THE EXPECTATION OF A HIGH POP/LOW ACCUMULATION SCENARIO. THIS
MOISTURE WILL SEED ENHANCEMENT FROM LAKE MICHIGAN AS INSTABILITY
INCREASES INTO THE 15-20C RANGE FOR LAKE TO 850 MB DELTA-T. THE MAIN
LIMITING FACTOR WILL BE THE STRONG WIND SPEED AND STEADY VEERING
TREND THAT WILL PREVENT ANY DOMINANT BAND FORMATION. PLAN TO FAVOR
THE TRI CITIES AND THUMB WITH CATEGORICAL POPS DURING THE AFTERNOON
AND LIKELY INTO THE THE EVENING WITH 1 TO 2 INCHES OF ACCUMULATION
BEFORE THE WIND SHIFT TOWARD THE NORTHWEST FAVORS AREAS SOUTH OF
INTERSTATE 69 TOWARD SUNRISE WEDNESDAY.
LONG TERM...
ALTHOUGH THE 500 MB LOW/MID LEVEL COLD POOL WILL BE MOVING INTO NEW
ENGLAND ON WEDNESDAY...A SHALLOW (SFC-925 MB) BACK DOOR COLD FRONT
WILL ATTEMPT TO MAKE INROADS INTO SOUTHERN LOWER MICHIGAN.
925 MB TEMPS OF -16 TO -17 C FORECASTED TO WORK THROUGH THE THUMB
REGION...WITH LOW LEVEL FLOW JUST SLIGHTLY WEST OF DUE NORTH.
SO...REASONABLE EXPECTATION SOME LAKE EFFECT SNOW SHOWER ACTIVITY
WILL BRUSH THE SHORELINE...BUT SHALLOW NATURE OF THE ACTIVITY
(MODERATING 850 MB TEMPS) SHOULD PREVENT ACTIVITY FROM GETTING OUT
OF HAND. 1042 MB HIGH OVER ONTARIO WILL NOSE INTO SOUTHEAST MICHIGAN
ON THURSDAY...AS AMPLIFIED UPPER LEVEL RIDGE MOVES OVER THE WESTERN
GREAT LAKES. POTENT UPPER WAVE JUST OFF THE PACIFIC NORTHWEST COAST
EARLY THIS MORNING STILL PROGGED TO ROTATE THROUGH THE FOUR CORNERS
REGION LATE WEDNESDAY...BUT TRACKING JUST A TOUCH FARTHER
EAST...OVER/NEAR SIOUX FALLS SOUTH DAKOTA THURSDAY NIGHT (PER 00Z
GFS/EURO). DRAMATIC WEST-EAST SHEARING OF THE UPPER LEVEL
CIRCULATION WILL OCCUR...BUT STILL A PERIOD OF LARGE SCALE ASCENT/PV
ADVECTION FRIDAY MORNING TO OCCUR OVER SOUTHEAST MICHIGAN. THE BULK
OF THE LIFT WILL BE USED UP JUST TO SATURATE THE LOW LEVELS...AS THE
PREVIOUSLY MENTIONED HIGH OVER ONTARIO LEADS TO EASTERLY DRY LOW
LEVEL FLOW PERSISTING INTO FRIDAY. 00Z GFS NOT EVEN GIVING US A
TENTH OF AN INCH OF QPF...AS DEEPER MOISTURE SEEN IN THE 850-700
MB/PW FIELDS SKIRTS JUST TO THE SOUTHEAST OF THE CWA. STILL...DECENT
SHOT OF MOISTURE ADVECTION...AND PREFERENCE IS WITH THE STRONGER
CANADIAN/EURO WHICH MAINTAINS THE 500 MB LOW OVER MINNESOTA INTO THE
FIRST HALF OF THE WEEKEND. QPF FROM THOSE MODELS SUPPORTS A SOLID 1
TO TWO INCHES OF SNOW ON FRIDAY...WITH RELATIVELY LOW SNOW TO LIQUID
RATIOS...AS ZERO OR SLIGHTLY BETTER 850 MB TEMPS SEEN REACHING THE
OHIO BORDER.
THE MODEST MID LEVEL COLD POOL OVER MINNESOTA WILL BREAK OFF TO THE
EAST FOR THE WEEKEND...KEEPING TEMPERATURES IN CHECK...AS 850 MB
TEMPS LOOK TO BE HOVERING AROUND -10 C...AND WITH LIMITED
SUNSHINE...MAXES EXPECTED TO REMAIN GENERALLY BELOW 40 DEGREES.
ALTHOUGH...WE WILL HAVE THE DRY SLOT WORKING THROUGH SATURDAY
MORNING...WHICH COULD BE THE DAY WE SNEAK UP TO 40 DEGREES.
MARINE...
DEEP LOW PRESSURE MOVING THROUGH THE STRAITS WILL PULL A STRONG COLD
FRONT THROUGH LAKE HURON AND LOWER MICHIGAN EARLY IN THE MORNING.
WESTERLY GALES WILL DEVELOP AFTER THE FRONTAL PASSAGE AND THEN
PERSIST TONIGHT THROUGH WEDNESDAY WHILE VEERING TO NORTHWEST OVER
THE OPEN WATERS OF LAKE HURON. POLAR AIR SURGING BACK INTO THE
REGION WILL CHANGE RAIN BACK TO SNOW AND ALSO LEAD TO A SUBSTANTIAL
FREEZING SPRAY HAZARD OVER THE OPEN WATERS TONIGHT THROUGH
WEDNESDAY. THE STRONG WINDS AND RESULTING LARGE WAVES WILL COMBINE
WITH NEAR IDEAL WATER TEMPERATURE FOR WIDESPREAD FREEZING SPRAY TO
BECOME HEAVY. MARINE CONDITIONS WILL THEN IMPROVE CONSIDERABLY BY
THURSDAY AS HIGH PRESSURE SETTLES OVER THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055-MIZ060-
MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075-MIZ076-MIZ082-
MIZ083...UNTIL 7 PM TUESDAY.
LAKE HURON...
GALE WARNING...LHZ361...UNTIL 7 PM WEDNESDAY.
HEAVY FREEZING SPRAY WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-
LHZ464...FROM 7 PM TUESDAY TO 7 PM WEDNESDAY.
GALE WARNING...LHZ362-LHZ363...UNTIL 7 PM WEDNESDAY.
GALE WARNING...LHZ421-LHZ422-LHZ441-LHZ442-LHZ443-LHZ462-LHZ463-
LHZ464...UNTIL MIDNIGHT WEDNESDAY.
LAKE ST CLAIR...
GALE WARNING...UNTIL MIDNIGHT WEDNESDAY.
MI WATERS OF LAKE ERIE...
GALE WARNING...UNTIL MIDNIGHT WEDNESDAY.
&&
$$
UPDATE.......HLO
AVIATION.....BT
SHORT TERM...BT
LONG TERM....SF
MARINE.......BT
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DULUTH MN
1233 PM CST TUE FEB 19 2013
.UPDATE...LET WIND CHILL ADVISORY EXPIRE AT SCHEDULED TIME SINCE
MOST LOCATIONS ACROSS OUR CWA HAVE WARMED ABOVE ADVISORY
THRESHOLD. MADE SOME MINOR ADJUSTMENTS TO POPS AND WX AS WELL FOR
THE LAKE EFFECT SNOW EVENT ALONG THE SOUTHSHORE. OTHERWISE GOING
FCST LOOKS GOOD.
&&
.PREV DISCUSSION... /ISSUED 1127 AM CST TUE FEB 19 2013/
AVIATION...../18Z TAF ISSUANCE/
MAINLY VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. THE ONLY
EXCEPTION WILL BE HIB WHERE SOME BLOWING SNOW WILL BRING SOME MVFR
VISIBILITIES FOR SEVERAL HOURS THIS AFTERNOON. THE GUSTY NORTH TO
NORTHWESTERLY WINDS WILL DIMINISH THIS EVENING. SKIES WILL BE MOSTLY
CLEAR THROUGHOUT THIS TAF FORECAST PERIOD. EXPECT LIGHT WINDS FROM
THE NORTHEAST BY THE END OF THIS TAF FORECAST PERIOD.
PREV DISCUSSION... /ISSUED 321 AM CST TUE FEB 19 2013/
CURRENT...VERY DEEP MID LVL TROF CONTINUES TO AMPLIFY AS IT CRAWLS
ACROSS CWA EARLY THIS MORNING. SFC LOW OVER ERN WISC IS INTENSIFYING
AS IT MOVES TOWARDS ERN END OF LAKE SUPERIOR. LARGE SHIELD OF DEEP
LAYER MOISTURE ACCOMPANIED BY COLD ADVECTION IS KEEPING LIGHT SNOW
ACROSS REGION. A STANDING WAVE IS INDICATED... ACROSS DOUGLAS COUNTY
AND INTO SE CARLTON COUNTY NEAR HOLYOKE... IN THE ANIMATED 88D
REFL/VEL PRODUCTS AS NW FLOW INCREASES. SFC PRESS GRADIENT NEARLY
20MB ACROSS CWA WITH GUSTY WINDS ACROSS MOST OF MN ZONES. VERY
STRONG GUSTS ALONG NORTH SHORE FROM TWIN PORTS TO GRAND PORTAGE.
LOCAL KATABATIC ENHANCEMENT OCCURING FROM SILVER BAY NORTH TO BORDER
WHERE INLAND TERRAIN IS HIGHER. GUST OVER 50 MPH HAVE OCCURED IN
THIS CORRIDOR WITH HRRR 3KM OUTPUT SUGGESTING GUSTS MAY REACH 60 MPH
THROUGH EARLY MORNING. ARCTIC AIR HAS INFILTRATED THE NORTHWESTERN
CWA WITH SFC TEMPS BELOW ZERO. WINDCHILL ADVISORY MAY NOT VERIFY IN
MANY AREAS UNTIL BETWEEN 12Z-15Z WHEN MIN TEMPS ARE REACHED AND WIND
SPEEDS REMAIN RELATIVELY HIGH. .
TODAY/TONIGHT...SLOW MOVING MID LVL TROF WILL KEEP A CYCLONIC AND
RELATIVELY MOIST CIRCULATION OVER THE REGION. GUSTY WINDS ARE EXPECTD
TO CONTINUE AS SFC PRESS GRADIENT REMAINS QUITE LARGE ACROSS CWA.
BUFKIT MOMENTUM TRANSFER PROFILES SHOW GUSTS MAY LINGER WELL INTO
THE NIGHT AS WELL. NORTH SHORE STILL SUSCEPTIBLE TO KATABATIC
ENHANCEMENT OFF HIGHER PLATEAU WEST OF LAKE SUPERIOR...ESPECIALLY
COOK COUNTY THROUGH MID MORNING. DEEP LAYER DRYING WILL OCCUR FROM
WEST TO EAST TODAY OVER THE MN ZONES. MAIN STORY OVER WISC WILL BE
CONTINUATION OF LES ACROSS SNOW BELTS. LAKE INDUCED CAPE FORECAST
TO INCREASE TO 400/500 J/KG THIS AFTN. INVERSION HEIGHTS ARE
EXPECTED TO LIFT TO ABOUT 4K FT THIS AFTERNOON BEFORE LOWERING TO 2K
FT AFTER MDINIGHT TONIGHT. WILL KEEP CURRENT ADVISORY/WARNING FOR
SOUTH SHORE. WILL NEED ANOTHER WIND CHILL ADVISORY TONIGHT FOR MOST
OF CWA. WILL LET DAY SHIFT ISSUE THIS AFTER CURENT WINDC ADV EXPIRES.
MAX TEMPS TODAY WILL STRUGGLE ALL DAY TO GET ABOVE ZERO ACROSS THE
BORDERLAND AND IRON RANGE. SINGLE DIGITS ELSEWHERE. LOWERED PREVIOUS
TEMP FCST OVER INTERIOR WISC IN LINE WITH ECBC VALUES AND LOWER
TEMPS OF SREF PLUMES.
TOMORROW...PROGRESSIVE FLOW ALOFT WILL SEND A MID LVL RIDGE
OVERHEAD. STRONG SFC HIGH CENTERED OVER NRN ONTARIO WILL BUILD SOUTH
INTO CWA. ABUNDANT SUNSHINE TO START THE DAY ALTHOUGH HIGH CLOUDS
MAY INCREASE FROM THE SOUTHWEST IN THE AFTERNOON IN RESPONSE TO
UPPER LEVEL WARM ADVECTION FROM SRN ROCKIES STORM. TEMPS REMAIN
WELL BELOW CLIMO.
LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY.
FOCUS IN LONG TERM ON ACTIVE PATTERN FOR THE UPPER MIDWEST LATE IN
THE WEEK...AND EARLY NEXT WEEK.
UPPER LEVEL RIDGE WILL AMPLIFY OVER THE WRN GREAT LAKE REGION WED
NIGHT AS A VORT MAX ROUNDS THE BASE OF A LONG WAVE TROUGH IN THE SW
CONUS...DEEPENING INTO A CLOSED LOW AS IT LIFTS ACROSS THE CENTRAL
PLAINS THURSDAY. THE 00Z MODELS ARE SHOWING GOOD AGREEMENT THAT THE
H50 LOW PUSHES INTO THE SRN DAKOTAS/MINN THURSDAY
EVENING...CENTERING OVER MINNESOTA FRIDAY NIGHT. MEANWHILE...THE SFC
LOW REMAINS TO THE SW OF THE H50 LOW...TRACKING ACROSS IOWA THROUGH
THE DAY FRIDAY...REACHING UPPER MICHIGAN/CEN GREAT LAKES FRIDAY
NIGHT. HAVE MADE VERY LITTLE CHANGES TO POPS THURSDAY NIGHT/FRIDAY
AS THE LEADING EDGE OF THE MAIN SWATH OF SNOW IS EXPECTED TO IMPACT
THE SRN DLH ZONES THURSDAY EVENING...LIFTING OVER MUCH OR ALL OF THE
NORTHLAND THROUGH FRIDAY. TEMPERATURE PROFILES CONTINUE TO SUGGEST
PTYPE OF ALL SNOW FOR THE DLH CWA.
ALTHOUGH UNCERTAINTY REMAINS...MODELS HAVE SHOWN DECENT RUN TO RUN
AGREEMENT THAT A BAND OF HEAVY SNOW DEVELOPS ACROSS THE SRN HALF OF
MINNESOTA THURSDAY NIGHT INTO FRIDAY MORNING. LATEST GFS/ECM
CONTINUE TO SHOW VERY DRY AIR ASSOCIATED WITH A RIDGE AXIS EXTENDING
SOUTH FROM ONTARIO WILL BE DIFFICULT TO ERODE THURSDAY NIGHT...SO
HAVE TRENDED A WITH A SLOWER TIMING FOR INTRODUCING POPS. THE LATEST
NAM BUFR SOUNDING AT KBRD/KINL/KHYR DEPICT PWATS INITIALLY THURSDAY OF
ONLY 0.08". HOWEVER...THERE IS MOISTURE ASSOCIATED WITH THE LOW THAT
DOES ADVECT INTO THE REGION AS THE H50 LOW APPROACHES...ALLOWING
PWATS TO INCREASE TO AROUND 0.3" THROUGH FRIDAY NIGHT AT MOST
LOCATIONS.
HAVE INCREASED TO BROADBRUSH LIKELY POPS FOR LIGHT SNOW FRIDAY.
MODELS SUGGEST THE H50 LOW HANGS AROUND THE GREAT LAKES REGION
THROUGH THE WEEKEND...KEEPING CYCLONIC FLOW...CLOUDS AND LIGHT SNOW
CHANCES FOR THE NORTHLAND.
ALTHOUGH THE GFS IS SHOWING A TREND TOWARDS THE ECM SOLUTION FOR THE
SYSTEM THAT WILL IMPACT THE REGION EARLY NEXT WEEK...THERE REMAINS
LARGE DIFFERENCES IN TIMING AND STORM TRACK. THE ECM SOLUTION LIFTS
THE CLOSED LOW OVER THE DAKOTAS TUESDAY...WHILE THE LATEST GFS
SUGGESTS A FASTER AND MORE EASTERLY TRACK WITH THE H50 LOW PASSING
OVER MINN/WIS MONDAY NIGHT.
&&
.POINT TEMPS/POPS...
DLH -12 13 4 21 / 10 0 0 0
INL -24 8 -11 18 / 10 0 0 0
BRD -14 13 -3 21 / 10 0 0 10
HYR -14 15 -8 24 / 10 0 0 0
ASX -8 15 -1 23 / 50 20 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR WIZ004.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ002.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ003.
&&
$$
SHORT TERM...BERDES
AREA FORECAST DISCUSSION
NWS DULUTH MN
1127 AM CST TUE FEB 19 2013
.AVIATION...../18Z TAF ISSUANCE/
MAINLY VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. THE ONLY
EXCEPTION WILL BE HIB WHERE SOME BLOWING SNOW WILL BRING SOME MVFR
VISIBILITIES FOR SEVERAL HOURS THIS AFTERNOON. THE GUSTY NORTH TO
NORTHWESTERLY WINDS WILL DIMINISH THIS EVENING. SKIES WILL BE MOSTLY
CLEAR THROUGHOUT THIS TAF FORECAST PERIOD. EXPECT LIGHT WINDS FROM
THE NORTHEAST BY THE END OF THIS TAF FORECAST PERIOD.
&&
PREV DISCUSSION... /ISSUED 321 AM CST TUE FEB 19 2013/
CURRENT...VERY DEEP MID LVL TROF CONTINUES TO AMPLIFY AS IT CRAWLS
ACROSS CWA EARLY THIS MORNING. SFC LOW OVER ERN WISC IS INTENSIFYING
AS IT MOVES TOWARDS ERN END OF LAKE SUPERIOR. LARGE SHIELD OF DEEP
LAYER MOISTURE ACCOMPANIED BY COLD ADVECTION IS KEEPING LIGHT SNOW
ACROSS REGION. A STANDING WAVE IS INDICATED... ACROSS DOUGLAS COUNTY
AND INTO SE CARLTON COUNTY NEAR HOLYOKE... IN THE ANIMATED 88D
REFL/VEL PRODUCTS AS NW FLOW INCREASES. SFC PRESS GRADIENT NEARLY
20MB ACROSS CWA WITH GUSTY WINDS ACROSS MOST OF MN ZONES. VERY
STRONG GUSTS ALONG NORTH SHORE FROM TWIN PORTS TO GRAND PORTAGE.
LOCAL KATABATIC ENHANCEMENT OCCURING FROM SILVER BAY NORTH TO BORDER
WHERE INLAND TERRAIN IS HIGHER. GUST OVER 50 MPH HAVE OCCURED IN
THIS CORRIDOR WITH HRRR 3KM OUTPUT SUGGESTING GUSTS MAY REACH 60 MPH
THROUGH EARLY MORNING. ARCTIC AIR HAS INFILTRATED THE NORTHWESTERN
CWA WITH SFC TEMPS BELOW ZERO. WINDCHILL ADVISORY MAY NOT VERIFY IN
MANY AREAS UNTIL BETWEEN 12Z-15Z WHEN MIN TEMPS ARE REACHED AND WIND
SPEEDS REMAIN RELATIVELY HIGH. .
TODAY/TONIGHT...SLOW MOVING MID LVL TROF WILL KEEP A CYCLONIC AND
RELATIVELY MOIST CIRCULATION OVER THE REGION. GUSTY WINDS ARE EXPECTD
TO CONTINUE AS SFC PRESS GRADIENT REMAINS QUITE LARGE ACROSS CWA.
BUFKIT MOMENTUM TRANSFER PROFILES SHOW GUSTS MAY LINGER WELL INTO
THE NIGHT AS WELL. NORTH SHORE STILL SUSCEPTIBLE TO KATABATIC
ENHANCEMENT OFF HIGHER PLATEAU WEST OF LAKE SUPERIOR...ESPECIALLY
COOK COUNTY THROUGH MID MORNING. DEEP LAYER DRYING WILL OCCUR FROM
WEST TO EAST TODAY OVER THE MN ZONES. MAIN STORY OVER WISC WILL BE
CONTINUATION OF LES ACROSS SNOW BELTS. LAKE INDUCED CAPE FORECAST
TO INCREASE TO 400/500 J/KG THIS AFTN. INVERSION HEIGHTS ARE
EXPECTED TO LIFT TO ABOUT 4K FT THIS AFTERNOON BEFORE LOWERING TO 2K
FT AFTER MDINIGHT TONIGHT. WILL KEEP CURRENT ADVISORY/WARNING FOR
SOUTH SHORE. WILL NEED ANOTHER WIND CHILL ADVISORY TONIGHT FOR MOST
OF CWA. WILL LET DAY SHIFT ISSUE THIS AFTER CURENT WINDC ADV EXPIRES.
MAX TEMPS TODAY WILL STRUGGLE ALL DAY TO GET ABOVE ZERO ACROSS THE
BORDERLAND AND IRON RANGE. SINGLE DIGITS ELSEWHERE. LOWERED PREVIOUS
TEMP FCST OVER INTERIOR WISC IN LINE WITH ECBC VALUES AND LOWER
TEMPS OF SREF PLUMES.
TOMORROW...PROGRESSIVE FLOW ALOFT WILL SEND A MID LVL RIDGE
OVERHEAD. STRONG SFC HIGH CENTERED OVER NRN ONTARIO WILL BUILD SOUTH
INTO CWA. ABUNDANT SUNSHINE TO START THE DAY ALTHOUGH HIGH CLOUDS
MAY INCREASE FROM THE SOUTHWEST IN THE AFTERNOON IN RESPONSE TO
UPPER LEVEL WARM ADVECTION FROM SRN ROCKIES STORM. TEMPS REMAIN
WELL BELOW CLIMO.
LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY.
FOCUS IN LONG TERM ON ACTIVE PATTERN FOR THE UPPER MIDWEST LATE IN
THE WEEK...AND EARLY NEXT WEEK.
UPPER LEVEL RIDGE WILL AMPLIFY OVER THE WRN GREAT LAKE REGION WED
NIGHT AS A VORT MAX ROUNDS THE BASE OF A LONG WAVE TROUGH IN THE SW
CONUS...DEEPENING INTO A CLOSED LOW AS IT LIFTS ACROSS THE CENTRAL
PLAINS THURSDAY. THE 00Z MODELS ARE SHOWING GOOD AGREEMENT THAT THE
H50 LOW PUSHES INTO THE SRN DAKOTAS/MINN THURSDAY
EVENING...CENTERING OVER MINNESOTA FRIDAY NIGHT. MEANWHILE...THE SFC
LOW REMAINS TO THE SW OF THE H50 LOW...TRACKING ACROSS IOWA THROUGH
THE DAY FRIDAY...REACHING UPPER MICHIGAN/CEN GREAT LAKES FRIDAY
NIGHT. HAVE MADE VERY LITTLE CHANGES TO POPS THURSDAY NIGHT/FRIDAY
AS THE LEADING EDGE OF THE MAIN SWATH OF SNOW IS EXPECTED TO IMPACT
THE SRN DLH ZONES THURSDAY EVENING...LIFTING OVER MUCH OR ALL OF THE
NORTHLAND THROUGH FRIDAY. TEMPERATURE PROFILES CONTINUE TO SUGGEST
PTYPE OF ALL SNOW FOR THE DLH CWA.
ALTHOUGH UNCERTAINTY REMAINS...MODELS HAVE SHOWN DECENT RUN TO RUN
AGREEMENT THAT A BAND OF HEAVY SNOW DEVELOPS ACROSS THE SRN HALF OF
MINNESOTA THURSDAY NIGHT INTO FRIDAY MORNING. LATEST GFS/ECM
CONTINUE TO SHOW VERY DRY AIR ASSOCIATED WITH A RIDGE AXIS EXTENDING
SOUTH FROM ONTARIO WILL BE DIFFICULT TO ERODE THURSDAY NIGHT...SO
HAVE TRENDED A WITH A SLOWER TIMING FOR INTRODUCING POPS. THE LATEST
NAM BUFR SOUNDING AT KBRD/KINL/KHYR DEPICT PWATS INITIALLY THURSDAY OF
ONLY 0.08". HOWEVER...THERE IS MOISTURE ASSOCIATED WITH THE LOW THAT
DOES ADVECT INTO THE REGION AS THE H50 LOW APPROACHES...ALLOWING
PWATS TO INCREASE TO AROUND 0.3" THROUGH FRIDAY NIGHT AT MOST
LOCATIONS.
HAVE INCREASED TO BROADBRUSH LIKELY POPS FOR LIGHT SNOW FRIDAY.
MODELS SUGGEST THE H50 LOW HANGS AROUND THE GREAT LAKES REGION
THROUGH THE WEEKEND...KEEPING CYCLONIC FLOW...CLOUDS AND LIGHT SNOW
CHANCES FOR THE NORTHLAND.
ALTHOUGH THE GFS IS SHOWING A TREND TOWARDS THE ECM SOLUTION FOR THE
SYSTEM THAT WILL IMPACT THE REGION EARLY NEXT WEEK...THERE REMAINS
LARGE DIFFERENCES IN TIMING AND STORM TRACK. THE ECM SOLUTION LIFTS
THE CLOSED LOW OVER THE DAKOTAS TUESDAY...WHILE THE LATEST GFS
SUGGESTS A FASTER AND MORE EASTERLY TRACK WITH THE H50 LOW PASSING
OVER MINN/WIS MONDAY NIGHT.
&&
.POINT TEMPS/POPS...
DLH 4 -12 13 4 / 20 10 0 0
INL 0 -24 8 -11 / 10 10 0 0
BRD 5 -14 13 -3 / 10 10 0 0
HYR 7 -14 15 -8 / 30 10 0 0
ASX 9 -8 15 -1 / 60 50 20 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WIND CHILL ADVISORY UNTIL NOON CST TODAY FOR MNZ010>012-018>021-
025-026-033>037.
WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR WIZ004.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ002.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ003.
&&
$$
AVIATION...KK
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
321 PM MST TUE FEB 19 2013
.DISCUSSION...
LAST TWO HOURS OF SURFACE OBS AND THE CIRA DERIVED PWAT VALUES SHOW
SOME OF THE STRONGEST MOISTURE ADVECTION THIS FORECASTER HAS SEEN IN
A LONG TIME. DEWPOINT VALUES ACROSS SOUTHERN NM ROSE FROM THE SINGLE
DIGITS INTO THE 30S AND LOW 40S BTWN 15Z AND 21Z. SOUTH TO SOUTHWEST
FLOW USHERING IN THIS MOISTURE WILL SPREAD ACROSS NM TONIGHT...THUS
OVERNIGHT LOWS WILL BE SIGNIFICANTLY WARMER THAN THE PAST SEVERAL.
12Z/18Z BUFKIT PROFILES AND LATEST RUC SOLUTION SHOWING BIG TIME TOP
DOWN MOISTENING THIS EVENING LEADING TO A LOW CLOUD LAYER WITH LIGHT
RAIN SHOWERS AND DRIZZLE ACROSS MUCH OF THE EAST. HAVE RAISED POPS
IN THIS AREA CONSIDERABLY. THIS DEEP SURGE OF LOW LEVEL MOISTURE IS
IN RESPONSE TO A DEEPER 534DM H5 LOW OVER CENTRAL CALIFORNIA DIGGING
CONTINUOUSLY FARTHER SOUTH EACH RUN...THUS BACKING LOW LEVEL WIND
FIELDS MORE EFFICIENTLY.
WITH THIS TRACK AND DEEPER MOISTURE HAVE ESSENTIALLY INCREASED POPS
ALL AREAS. ACCORDINGLY THE 700-500MB LAYER WIND FIELDS HAVE SHIFTED
MORE INTO SOUTHERN NM INCREASING CONFIDENCE THAT HIGH WIND SPEEDS
WILL NOT IMPACT OUR REGION. THE SUITE OF HI RES MODEL SOLUTIONS AND
THE FOCUS FOR DYNAMICS ON THE LATEST MODEL SOLUTIONS HAVE INCREASED
CONFIDENCE ENOUGH TO UPGRADE THE WINTER STORM WATCH TO A WARNING FOR
ALL MT ZONES AND CONVERT TO ADVISORY FOR A FEW OTHERS. ALSO ADDED
THE SANGRE DE CRISTO MTS TO THE WARNING. THE MAIN IMPACT PERIOD FOR
MOIST UPSLOPE COLD ADVECTIVE WESTERLY FLOW WILL BE WEDNESDAY NIGHT
INTO THURSDAY...SO THAT SEGMENT WILL BE VALID FOR SLIGHTLY LONGER.
TEMPS WILL TAKE A NOSE DIVE WEDNESDAY AFTERNOON FROM WEST TO EAST...
WITH A FEW AREAS OUT WEST SEEING HIGHS IN THE MORNING.
WE SHOULD NOT FORGOT THAT MOIST INSTABILITY ALONG THE PACIFIC COLD
FRONTAL BNDRY WILL BE SUFFICIENT TO GENERATE A LINE OF STORMS OVER
THE FAR EASTERN PLAINS LATE WEDNESDAY AFT. BLOWING DUST WILL BE AN
ISSUE BEHIND THIS FRONT FOR THE PECOS AND LOWER RIO GRANDE VALLEY
AREAS. DID REMOVE MOST OF THE BLOWING SNOW WORDING FOR THE NORTH
AND WEST AS AGAIN THE WINDS APPEAR STRONGEST MUCH FARTHER SOUTH.
A SECONDARY WAVE WILL SLIDE OVER THE AREA THURSDAY/FRIDAY WITH WEAK
FORCING AND SLIGHTLY MORE COLD ADVECTION. THIS FEATURE WILL FOCUS
THE ACTION MAINLY ON THE HIGHER TERRAIN WHERE MOISTURE FROM THE
FIRST SYSTEM IS SQUEEZED OUT. A BRIEF BREAK WILL SLIDE OVER LATE
FRIDAY/SATURDAY...BEFORE ANOTHER WIND BAG ARRIVES SUNDAY. MODELS
JUST KEEP IT COMING NEXT WEEK WITH ANOTHER POTENTIAL STORM TUESDAY.
GUYER
&&
.FIRE WEATHER...
A STRING OF WEATHER SYSTEMS WILL CROSS THE FORECAST AREA WEDNESDAY
THROUGH MONDAY. THERE WILL BE SOME FIRE WEATHER CONCERNS EAST OF THE
CENTRAL MOUNTAINS SATURDAY...MONDAY AND ESPECIALLY SUNDAY.
THE FIRST STORM IN THE SERIES WILL PROBABLY PRODUCE THE MOST
PRECIPITATION AND THE STRONGEST WINDS. MODELS KEEP NUDGING THIS
SYSTEM FURTHER SOUTH WITH EACH RUN...AND THE LOW PRESSURE CENTER IS
NOW EXPECTED TO PASS EASTWARD FROM QUEMADO TO TUCUMCARI WEDNESDAY
THROUGH WEDNESDAY NIGHT. THE POTENTIAL EXISTS FOR SEVERAL INCHES OF
SNOW BY THURSDAY MORNING ACROSS THE NORTHERN AND WESTERN
MOUNTAINS...WITH A FEW INCHES TO POSSIBLY A HALF FOOT AT LOWER
ELEVATIONS OF THE WEST CENTRAL AND NORTHWEST PLATEAU AND LIGHTER
AMOUNTS IN THE UPPER RIO GRANDE VALLEY. FARTHER SOUTH AND EAST THE
MAIN WEATHER CONCERN WILL BE WIND. THE POLAR JET STREAM WILL CROSS
SOUTHERN NM ON WEDNESDAY...THEN A STRONG SURFACE LOW IN THE LEE OF
THE SOUTHERN CO ROCKIES WILL KEEP THE PRESSURE GRADIENT TIGHT AND
WINDS STRONG ACROSS EASTERN NM WEDNESDAY NIGHT THROUGH THURSDAY.
GUSTS UP TO 50 MPH ARE EXPECTED FROM AROUND SOCORRO TO AROUND GRAN
QUIVIRA DURING EARLY AFTERNOON WEDNESDAY...THEN THESE STRONG WINDS
SHOULD SPREAD NORTHEASTWARD ALONG THE EAST SLOPES OF THE CENTRAL AND
SOUTHERN SANGRE DE CRISTO MOUNTAINS DURING THE LATE AFTERNOON AND
NIGHT. A COLD FRONT WILL ALSO CROSS FROM THE WEST WEDNESDAY AND
WEDNESDAY NIGHT...WITH MECHANICAL MIXING HELPING TO KEEP WINDS GOING
THROUGH THE NIGHT IN THE EAST.
IN THE WAKE OF THE COLD FRONT...HIGH TEMPERATURES THURSDAY WILL FALL
A FEW TO 8 DEGREES BELOW WEDNESDAYS READINGS. THE SURFACE PRESSURE
GRADIENT WILL REMAIN TIGHT IN THE EAST. WIND GUSTS TO 50 MPH ARE
EXPECTED TO CONTINUE FROM CLINES CORNERS TO SUMNER LAKE UNTIL SUNSET
THURSDAY EVENING. JUST AS THE FIRST UPPER LOW EXITS THURSDAY
MORNING...A TRAILING UPPER TROUGH WILL DIVE SOUTHEASTWARD THROUGH
THE FORECAST AREA THURSDAY AFTERNOON THROUGH FRIDAY. THIS WILL CAUSE
SNOW SHOWERS TO LINGER...BUT THIS SYSTEM WILL BE SIGNIFICANTLY
DRIER. THERE MAY BE A FEW INCHES OF ADDITIONAL SNOW ACCUMULATION IN
THE NORTHERN AND POSSIBLY THE WESTERN MOUNTAINS. HIGH TEMPERATURES
THURSDAY AND FRIDAY WILL VARY FROM 5 TO 20 DEGREES BELOW NORMAL.
THE AREA WILL BE BETWEEN STORM SYSTEMS SATURDAY. WEAK RIDGING WILL
PRODUCE TEMPERATURES 8 TO 15 DEGREES WARMER THAN FRIDAYS READINGS.
WEST WINDS WILL BECOME BREEZY TO WINDY AGAIN IN THE LEE OF THE
CENTRAL MOUNTAINS DUE TO A STRONG SURFACE LEE TROUGH AND
STRENGTHENING WINDS ALOFT AHEAD OF THE NEXT WEATHER SYSTEM. POCKETS
OF MINIMUM HUMIDITIES IN THE LOWER TEENS SHOULD RESULT IN AN HOUR OR
TWO OF CRITICAL FIRE WEATHER CONDITIONS ON THE EAST CENTRAL PLAINS.
A MORE CRITICAL FIRE WEATHER PATTERN MAY DEVELOP FOR NM SUNDAY AS AN
UPPER TROUGH STRENGTHENS INTO A CLOSED UPPER LOW WHILE PASSING
EASTWARD OVER CO AND/OR NORTHERN NM. THIS WILL STEER A STRONG POLAR
JET STREAK OVER THE SOUTHERN ROCKIES WHILE DRIVING A COLD FRONT
SOUTHWARD THROUGH NM. NW WIND GUSTS MAY PEAK AROUND 50 MPH FROM THE
SANDIA AND MANZANO MOUNTAINS EASTWARD ONTO THE EAST CENTRAL PLAINS.
MUCH OF THIS AREA MAY EXPERIENCE SEVERAL HOURS OF CRITICAL FIRE
WEATHER CONDITIONS. MODELS DISAGREE ON HOW FAR SOUTH THE UPPER LOW
WILL CROSS. IF IT DROPS AS FAR SOUTH AS NORTHERN NM...THEN THE
NORTHERN AND WESTERN MOUNTAINS COULD RECEIVE A FEW TO SEVERAL
ADDITIONAL INCHES OF SNOW BY MONDAY MORNING. MONDAY SHOULD SEE HIGH
TEMPERATURES ROUGHLY 6 TO 16 DEGREES BELOW NORMAL. AFTER AN EXTENDED
PERIOD OF GOOD TO EXCELLENT VENTILATION...MAX VENT RATES MONDAY MAY
NOT GET OUT OF THE POOR CATEGORY IN MANY LOWER ELEVATION
LOCATIONS.
44
&&
.AVIATION...
18Z TAF CYCLE
SOUTHERLY FLOW WILL STRENGTHEN OVER NM TODAY AND PERSIST THROUGH
TONIGHT AS AN UPPER LEVEL LOW PRESSURE SYSTEM APPROACHES FROM THE
WEST. LOW LEVEL MOISTURE ADVECTION SHOULD CAUSE LOW CLOUDS TO
OVERSPREAD MUCH OF THE E CENTRAL AND SE PLAINS DURING THE
EVENING...BEFORE PUSHING INTO NE AREAS AFTER MIDNIGHT AND
POSSIBLY OVER KSAF WITH A SE CANYON WIND TOWARD SUNRISE. THERE IS ONLY
ABOUT 50 PERCENT CONFIDENCE THAT LOW CLOUDS WILL REACH KSAF. THE MVFR
AND IFR LOW CLOUDS MAY BE ACCOMPANIED BY LOCALLY DENSE FOG E OF
THE CENTRAL MTN CHAIN TONIGHT...BUT PERSISTENT WINDS SHOULD KEEP
THE FOG AT BAY IN MANY LOCATIONS. ISOLD -SHRA MAY ALSO DEVELOP
ACROSS THE E CENTRAL AND SE PLAINS OVERNIGHT...WHILE ISOLD TO SCT
-SHSN FAVOR LOCATIONS ALONG AND W OF THE CONTDVD. PCPN WILL BECOME
MORE WDSPR OVER W AND N AREAS WEDNESDAY AS A COLD FRONT CROSSES
THE NM/AZ BORDER. AHEAD OF THE FRONT...WINDS WILL SHIFT OUT OF THE
SW AND STRENGTHEN WITH GUSTS 30 TO 45 KT AS THE POLAR JET MOVES
OHD. A FEW TS WILL ALSO BE POSSIBLE ACROSS THE E CENTRAL AND NE
PLAINS WEDNESDAY AFTN.
44
&&
.PRELIMINARY POINT TEMPS/POPS...
FARMINGTON...................... 29 42 26 42 / 10 80 60 20
DULCE........................... 19 38 17 38 / 20 80 70 30
CUBA............................ 25 40 18 39 / 5 60 80 30
GALLUP.......................... 27 40 20 43 / 10 70 60 20
EL MORRO........................ 22 37 15 32 / 10 80 80 30
GRANTS.......................... 23 43 17 42 / 5 40 60 10
QUEMADO......................... 26 38 17 36 / 20 70 60 20
GLENWOOD........................ 26 39 15 40 / 5 60 60 5
CHAMA........................... 22 34 15 32 / 30 80 80 40
LOS ALAMOS...................... 30 41 22 38 / 5 30 70 20
PECOS........................... 29 41 20 35 / 20 20 60 20
CERRO/QUESTA.................... 17 38 16 35 / 5 30 70 20
RED RIVER....................... 20 31 13 30 / 20 60 80 40
ANGEL FIRE...................... 18 36 12 29 / 10 50 70 30
TAOS............................ 25 41 21 38 / 5 30 70 20
MORA............................ 26 40 19 37 / 20 30 60 20
ESPANOLA........................ 30 47 24 45 / 5 10 60 10
SANTA FE........................ 31 42 21 38 / 10 20 70 20
SANTA FE AIRPORT................ 32 46 22 42 / 5 20 60 10
ALBUQUERQUE FOOTHILLS........... 34 46 24 44 / 5 10 50 5
ALBUQUERQUE HEIGHTS............. 36 49 26 46 / 5 10 40 5
ALBUQUERQUE VALLEY.............. 36 51 25 49 / 5 10 40 5
ALBUQUERQUE WEST MESA........... 35 50 25 50 / 5 10 40 5
LOS LUNAS....................... 34 51 24 49 / 5 10 30 5
RIO RANCHO...................... 35 49 25 47 / 5 10 40 5
SOCORRO......................... 33 53 26 54 / 5 5 30 5
SANDIA PARK/CEDAR CREST......... 32 43 22 43 / 20 30 60 20
TIJERAS......................... 33 45 24 46 / 5 20 60 10
MORIARTY/ESTANCIA............... 32 46 21 41 / 20 10 60 10
CLINES CORNERS.................. 31 42 21 39 / 30 20 50 10
GRAN QUIVIRA.................... 33 44 21 42 / 20 10 40 10
CARRIZOZO....................... 33 49 23 45 / 10 10 30 5
RUIDOSO......................... 32 43 21 38 / 30 20 50 10
CAPULIN......................... 28 42 22 31 / 30 40 60 30
RATON........................... 25 46 23 41 / 20 30 50 20
SPRINGER........................ 27 47 24 46 / 20 20 40 20
LAS VEGAS....................... 29 44 20 42 / 30 20 40 10
CLAYTON......................... 32 45 27 39 / 40 30 60 30
ROY............................. 34 47 26 45 / 40 20 40 10
CONCHAS......................... 41 56 32 55 / 40 10 30 5
SANTA ROSA...................... 39 56 29 51 / 30 5 20 5
TUCUMCARI....................... 42 56 32 56 / 50 10 30 5
CLOVIS.......................... 39 55 29 53 / 40 10 20 5
PORTALES........................ 40 57 31 55 / 40 10 20 5
FORT SUMNER..................... 42 62 31 54 / 30 5 20 5
ROSWELL......................... 42 68 33 60 / 40 5 10 5
PICACHO......................... 35 58 27 51 / 30 5 20 5
ELK............................. 34 52 24 46 / 40 10 30 5
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 11 AM WEDNESDAY TO MIDNIGHT MST WEDNESDAY NIGHT
FOR THE FOLLOWING ZONES...NMZ520-524>526-539-540.
WINTER STORM WARNING FROM 6 AM WEDNESDAY TO 6 AM MST THURSDAY FOR
THE FOLLOWING ZONES...NMZ502>506-508>511.
WINTER STORM WARNING FROM 6 AM WEDNESDAY TO NOON MST THURSDAY FOR
THE FOLLOWING ZONES...NMZ512>514.
WINTER WEATHER ADVISORY FROM 6 AM WEDNESDAY TO 6 AM MST THURSDAY
FOR THE FOLLOWING ZONES...NMZ501-507-516.
&&
$$
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
310 PM EST TUE FEB 19 2013
.SYNOPSIS...
A COLD FRONT WILL SWING THROUGH THE REGION THIS EVENING ALONG WITH
WIDESREAD...ALBEIT LIGHT RAIN AND SNOW. TEMPERATURES TREND COOLER
BY TOMORROW INTO LATE WEEK AS LOW PRESSURE DRIFTS SLOWLY ACROSS THE
AREA. THIS WILL ALSO BRING PLENTY OF CLOUDS AND SCATTERED TO
NUMEROUS SNOW SHOWERS TO OUR AREA...ESPECIALLY ACROSS THE NORTHERN
MOUNTAINS. THE UNSETTLED PATTERN WITH CHANCES OF RAIN AND SNOW
SHOWERS CONTINUES INTO NEXT WEEKEND AS TEMPERATURES TREND MILDER.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AS OF 310 PM EST TUESDAY...FORECAST REMAINS ON TRACK FOR THIS
EVENING INTO TONIGHT AS SURFACE COLD FRONT CURRENTLY ACROSS
WESTERN NEW YORK PROGRESSES STEADILY EAST ALONG WITH A PERIOD OF
LIGHT RAIN AND/OR SNOW. LOW TO MID LEVEL AIRMASS CONTINUES TO RUN
QUITE DRY AHEAD OF THE PRIMARY FRONTAL ZONE AND ASSOCIATED
PRECIPITATION SUCH THAT ONCE PRECIPITATION ARRIVES WET BULB
COOLING PROCESSES SHOULD ALLOW MANY AREAS TO TRANSITION TO A LIGHT
RAIN/SNOW MIX OR ALL SNOW. THAT SAID PLENTY OF AREAS IN THE
CHAMPLAIN VALLEY LIKELY TO HOLD AROUND THE 40F UNTIL PCPN ARRIVES
SO AN HOUR OR TWO OF PLAIN RAIN CERTAINLY POSSIBLE. MAIN IDEA IS
THAT PCPN WILL BE LIGHT WITH MODEL BLENDED QPF PROGS IN GOOD
AGREEMENT SHOWING ANYWHERE FROM A TENTH TO A QUARTER INCH ACROSS
OUR AREA WITH PERHAPS EVEN LESS IN THE NORTHERN CHAMPLAIN VALLEY
DUE TO SHADOWING EFFECTS. THUS ANY SNOW ACCUMULATIONS WILL BE
LIGHT AS WELL AND GENERALLY BELOW 3 INCHES. AS FRONTAL ZONE CLEARS
EAST LATER THIS EVENING LOWER TO MID LEVEL FLOW WILL TREND WEST TO
SOUTHWESTERLY UNDER MODEST COLD THERMAL ADVECTION AND A GRADUAL
COOLING OF SURFACE TEMPERATURES. SNOW SHOWER COVERAGE WILL ALSO
WANE OVERNIGHT. DID OPT TO STAY ON THE MILD SIDE OF MOS/RAW
MACHINE NUMBERS GIVEN AMPLE CLOUD COVER AND A MIXED NOCTURNAL
BOUNDARY LAYER OFFERING VALUES MAINLY IN THE 20S.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
AS OF 310 PM EST TUESDAY...BY WEDNESDAY PARENT OCCLUSION CURRENTLY
ACROSS THE NORTHERN GREAT LAKES WILL DRIFT SLOWLY INTO THE SLV AND
SOUTHERN QUEBEC KEEPING PLENTY OF CLOUDS ACROSS OUR AREA ALONG
WITH SCATTERED SNOW SHOWERS...MAINLY CENTRAL AND NORTH. WITH LOW
TO MID LEVEL FLOW REMAINING WESTERLY HIGHEST COVERAGE SHOULD BE
CONFINED TO THE HIGHER TERRAIN OF THE GREENS AND PORTIONS OF THE
SOUTHWESTERN ADIRONDACKS WHERE CONDITIONS WILL BE MARGINALLY
CONDUCIVE FOR SOME ENHANCED LAKE SNOWS. HIGHS NEAR LATE WINTER
SEASONAL LEVELS FROM 25 TO 32.
BY WEDNESDAY NIGHT INTO THE FIRST HALF OF THURSDAY OVERALL COVERAGE
OF SNOW SHOWERS SHOULD INCREASE ACROSS OUR CENTRAL AND NORTHERN
COUNTIES AS OCCLUSION TRUDGES SLOWLY EAST AND INCREASINGLY
MOIST/CYCLONIC FLOW DEVELOPS ACROSS THE AREA. A DISTINCT SURFACE
TROUGH PASSAGE WILL OCCUR DURING THIS PERIOD ALONG WITH DEVELOPING
BLOCKED FLOW AND WARM THERMAL ADVECTION ALOFT. THIS ALL SPELLS A
DECENT 12-18 HR PERIOD OF LIGHT TO MODERATE SNOWFALL IN OUR FAVORED
UPSLOPE AREAS WHERE SOME MODEST ACCUMULATIONS WILL CERTAINLY BE
POSSIBLE ABOVE 2000 FEET AND AT OUR NRN RESORTS. LOW LEVEL FLOW IS
WEST-NORTHWESTERLY ENOUGH HOWEVER THAT ACCUMULATIONS IN THE NRN
VALLEYS WILL BE CONSIDERABLY LESS. FURTHER SOUTH ONLY FLURRIES
EXPECTED. ONCE AGAIN KEPT OVERNIGHT LOWS ON THE MILD SIDE OF
GUIDANCE GIVEN AMPLE CLOUD COVER...MAINLY 10 TO 20. HIGHS BY
THURSDAY A TAD COOLER THAN WEDNESDAY...MAINLY 20S.
ON THURSDAY NIGHT SNOW SHOWER COVERAGE WANES AND COMES TO AN END
OVERNIGHT AS UPPER LOW PULLS EAST AND FAIRLY AMPLIFIED LOW TO MID
LEVEL RIDGING BUILDS EASTWARD. THUS SKIES SHOULD TREND CLEAR TO
PTLY CLOUDY AS LOWS BOTTOM OUT IN THE UPPER SINGLE DIGITS INTO THE
TEENS.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 PM EST TUESDAY...LARGE SCALE PATTERN WL CONT TO BE
PROGRESSIVE ACRS THE CONUS WITH SEVERAL SYSTEMS IMPACTING OUR CWA.
FIRST SYSTEM ARRIVES ON SATURDAY...WITH GFS/ECMWF AND GEM SHOWING
NO PHASING WITH NORTHERN/SOUTHERN STREAMS AND LIMITED IMPACT ACRS
OUR FA. NORTHERN STREAM ENERGY/MOISTURE WL TRACK ACRS THE CENTRAL
GREAT LAKES...WHILE SOUTHERN STREAM S/W ENERGY WL SLIDE TO OUR
SOUTH ACRS THE MID ATLANTIC STATES. THIS PLACES OUR CWA IN REGION
OF MID LVL DEFORMATION...ALONG WITH AN INVERTED TROF LIKE
FEATURE AT THE SFC. THIS COMBINED WITH SOME 850 TO 500MB RH WL
PRODUCE CHCS FOR LIGHT PRECIP SAT/SUN. LATEST THERMAL PROFILES SUGGEST
RAIN/SNOW VALLEYS AND MAINLY SNOW IN THE MTNS. BETTER S/W ENERGY
ROTATES THRU OUR CWA ON SUNDAY...WITH POTENTIAL FOR SOME ENHANCED
PRECIP. OVERALL...QPF BTWN THE TWO SYSTEMS WL BE LIGHT AND
SNOWFALL MINOR. PROGGED 85H TEMPS BTWN -4C AND -6C SUPPORT HIGHS
MAINLY IN THE 30S. OVERNIGHT LOWS WL BE MUCH ABOVE NORMAL WITH
EXPECTED CLOUDS...THINKING MAINLY IN THE 20S TO NEAR 30F CPV. HIGH
PRES AND DRY WEATHER RETURNS FOR MONDAY BEFORE NEXT SYSTEM ARRIVES
BY MIDWEEK. THIS LOOKS SIMILAR TO OUR EVENT TODAY/TONIGHT...WITH
CLOSED 5H/7H CIRCULATION TRACKING TO OUR NORTH WITH AN OCCLUDED
SFC TROF MOVING ACRS OUR REGION. STILL SOME UNCERTAINTY WITH
TIMING/IMPACT...BUT TEMPS LOOK TO BE ABOVE NORMAL GOING INTO NEXT
WEEK...WITH HIGHS M30S MTNS TO L40S VALLEYS.
&&
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
THROUGH 18Z WEDNESDAY...CNRT RADAR SHOWS A BAND OF MIXED PRECIP
MOVING TWD NORTHERN NY ATTM. DWPTS AHEAD OF THIS PRECIP ARE VERY
DRY...SO LEADING EDGE IS VIRGA AND NOT REACHING THE GROUND. IN
ADDITION...EXPECT THIS PRECIP TO COOL THE COLUMN ENOUGH TO SUPPORT
A RAIN CHANGING TO SNOW MIXTURE...ESPECIALLY AT SLK/MPV WITH
OCCASIONAL IFR LIKELY. BASED ON HRRR AND LATEST RADAR
TRENDS...THINKING IFR CONDITIONS WL ARRIVE IN SLK/MSS BY
19Z...WITH MVFR AT PBG/BTV/RUT BTWN 20-21Z...AND AFT 21Z AT MPV.
UPSTREAM OBS SHOW SOME IP/RA INITIALLY...BUT THIS QUICKLY CHANGES
TO -SN WITH VIS RANGING BTWN 1-3SM...WHICH IS SIMILAR TO WHAT WL
HAPPEN ACRS OUR TAF SITES. OTHERWISE...BAND OF DEEPEST MOISTURE
AND BEST LIFT WL BE NORTHEAST OF OUR TAF SITES BY 00Z
TONIGHT...WITH MAINLY SCATTERED SNOW SHOWERS ANTICIPATED...AND
OCCASIONAL MVFR CONDITIONS POSSIBLE. SOUTHERLY WINDS WL CONT TO BE
GUSTY BTWN 15 AND 25 KNTS...BEFORE PRECIP ARRIVES. SFC COLD FRNT
NEAR KBUF WL CAUSE A WIND SHIFT TO THE SOUTHWEST/WEST THIS
EVENING...WITH SOME POTENTIAL HIGHER GUSTS OVERNIGHT. MVFR WITH
OCCASIONAL IFR CONDITIONS IN -SHSN ACTIVITY WL BE POSSIBLE
OVERNIGHT AT SLK...ELSEWHERE MVFR/VFR CONDITIONS ARE EXPECTED.
OUTLOOK 18Z WEDNESDAY THROUGH FRIDAY...
A VERTICALLY STACKED AREA OF LOW PRES AND THE ASSOCIATED CYCLONIC
UPSLOPE FLW WL RESULT IN OCCASIONAL SNOW SHOWER ACTIVITY FROM 18Z
WEDS THRU 06Z FRIDAY. THIS COMBINED WITH SEVERAL EMBEDDED S/W`S
WL PRODUCE PERIODS OF SNOW SHOWERS WITH OCCASIONAL IFR LIKELY AT
SLK/MPV AND MVFR CONDITIONS POSSIBLE AT BTV/MSS/RUT/PBG. THE
GREATEST CHC FOR IFR CONDITIONS AT BTV/RUT/PBG WL BE ON THURSDAY.
OTHERWISE...SFC RIDGE AND IMPROVING CONDITIONS ARE ANTICIPATED ON FRIDAY.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...JMG
NEAR TERM...JMG
SHORT TERM...JMG
LONG TERM...TABER
AVIATION...TABER
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
303 PM EST TUE FEB 19 2013
.SYNOPSIS...
A LARGE UPPER LEVEL TROUGH OF LOW PRESSURE WILL MOVE EAST FROM THE GREAT
LAKES REGION TODAY AND BE SLOW TO CLEAR OUR AREA OVER THE NEXT COUPLE
OF DAYS. AS A RESULT...EXPECT UNSETTLED WEATHER WITH LIGHT RAIN OR SNOW
DEVELOPING THIS AFTERNOON AND CONTINUING AS SNOW SHOWERS LATER TONIGHT.
SOME MINOR SNOW ACCUMULATIONS ARE EXPECTED. MORE SNOW SHOWERS ARE EXPECTED
WEDNESDAY THROUGH THURSDAY...ESPECIALLY OVER THE MOUNTAINS...WHERE SOME
SNOW ACCUMULATIONS ARE EXPECTED.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
AS OF 1223 PM EST TUESDAY...VERY MINOR UPDATES TO HOURLY
TEMPERATURES AND SFC DEWPOINTS INTO EARLY EVENING PER LATEST
OBSERVATIONAL DATA. READINGS ALL OVER THE PLACE DEPENDING ON
LOCALE AND/OR DEGREE OF MIXING...RANGING FROM THE UPPER 20S TO THE
MID 40S. STILL LOOKING AT LIGHT RAIN/SNOW DEVELOPING ACROSS OUR
NRN NY COUNTIES THIS AFTERNOON...AND INTO VERMONT LATE OR BY EARLY
EVENING AS COLD FRONT ACROSS WESTERN NY STATE MAKES ITS WAY EAST.
REST OF FCST REMAINS IN GOOD SHAPE. ENJOY YOUR AFTERNOON.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH THURSDAY/...
AS OF 333 AM EST TUESDAY...DRY SLOT ASSOCIATED WITH THE UPPER LOW
WILL MOVE INTO THE AREA TONIGHT AND THIS WILL HELP BRING AN END TO
MOST OF THE PRECIPITATION AFTER MIDNIGHT. SOME LINGERING SNOW
SHOWERS ARE EXPECTED OVER THE MOUNTAINS AND PARTS OF THE SOUTHERN
SAINT LAWRENCE VALLEY WHERE SOME LAKE EFFECT SNOW MAY DEVELOP OFF
OF LAKE ONTARIO AND MOVE INTO THE AREA. MOST LOCATIONS SHOULD SEE
A DUSTING TO 2 INCHES OF SNOW TONIGHT WITH SLIGHTLY HIGHER AMOUNTS
IN THE MOUNTAINS. THE UPPER LOW MOVES ACROSS THE AREA ON WEDNESDAY
AND REACHES NOVA SCOTIA BY THURSDAY. FAVORABLE NORTHWEST FLOW
ALOFT DEVELOPS WITH THIS SCENARIO. THUS LOOKING AT ISOLATED TO
SCATTERED SNOW SHOWERS IN THE LARGER VALLEYS WEDNESDAY THROUGH
THURSDAY AND NUMEROUS SNOW SHOWERS FOR THE MOUNTAINS. COULD SEE
ANYWHERE FROM 1 TO 4 INCHES OF NEW SNOW IN THE MOUNTAINS BY LATE
IN THE DAY ON THURSDAY. LOOK FOR A COOLING TREND THROUGH MUCH OF
THE PERIOD. HIGH TEMPERATURES WILL STILL BE AROUND NORMAL ON
WEDNESDAY...BUT WILL BE SEVERAL DEGREES BELOW NORMAL BY THURSDAY.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 300 PM EST TUESDAY...LARGE SCALE PATTERN WL CONT TO BE
PROGRESSIVE ACRS THE CONUS WITH SEVERAL SYSTEMS IMPACTING OUR CWA.
FIRST SYSTEM ARRIVES ON SATURDAY...WITH GFS/ECMWF AND GEM SHOWING
NO PHASING WITH NORTHERN/SOUTHERN STREAMS AND LIMITED IMPACT ACRS
OUR FA. NORTHERN STREAM ENERGY/MOISTURE WL TRACK ACRS THE CENTRAL
GREAT LAKES...WHILE SOUTHERN STREAM S/W ENERGY WL SLIDE TO OUR
SOUTH ACRS THE MID ATLANTIC STATES. THIS PLACES OUR CWA IN REGION
OF MID LVL DEFORMATION...ALONG WITH AN INVERTED TROF LIKE
FEATURE AT THE SFC. THIS COMBINED WITH SOME 850 TO 500MB RH WL
PRODUCE CHCS FOR LIGHT PRECIP SAT/SUN. LATEST THERMAL PROFILES SUGGEST
RAIN/SNOW VALLEYS AND MAINLY SNOW IN THE MTNS. BETTER S/W ENERGY
ROTATES THRU OUR CWA ON SUNDAY...WITH POTENTIAL FOR SOME ENHANCED
PRECIP. OVERALL...QPF BTWN THE TWO SYSTEMS WL BE LIGHT AND
SNOWFALL MINOR. PROGGED 85H TEMPS BTWN -4C AND -6C SUPPORT HIGHS
MAINLY IN THE 30S. OVERNIGHT LOWS WL BE MUCH ABOVE NORMAL WITH
EXPECTED CLOUDS...THINKING MAINLY IN THE 20S TO NEAR 30F CPV. HIGH
PRES AND DRY WEATHER RETURNS FOR MONDAY BEFORE NEXT SYSTEM ARRIVES
BY MIDWEEK. THIS LOOKS SIMILAR TO OUR EVENT TODAY/TONIGHT...WITH
CLOSED 5H/7H CIRCULATION TRACKING TO OUR NORTH WITH AN OCCLUDED
SFC TROF MOVING ACRS OUR REGION. STILL SOME UNCERTAINTY WITH
TIMING/IMPACT...BUT TEMPS LOOK TO BE ABOVE NORMAL GOING INTO NEXT
WEEK...WITH HIGHS M30S MTNS TO L40S VALLEYS.
&&
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
THROUGH 18Z WEDNESDAY...CNRT RADAR SHOWS A BAND OF MIXED PRECIP
MOVING TWD NORTHERN NY ATTM. DWPTS AHEAD OF THIS PRECIP ARE VERY
DRY...SO LEADING EDGE IS VIRGA AND NOT REACHING THE GROUND. IN
ADDITION...EXPECT THIS PRECIP TO COOL THE COLUMN ENOUGH TO SUPPORT
A RAIN CHANGING TO SNOW MIXTURE...ESPECIALLY AT SLK/MPV WITH
OCCASIONAL IFR LIKELY. BASED ON HRRR AND LATEST RADAR
TRENDS...THINKING IFR CONDITIONS WL ARRIVE IN SLK/MSS BY
19Z...WITH MVFR AT PBG/BTV/RUT BTWN 20-21Z...AND AFT 21Z AT MPV.
UPSTREAM OBS SHOW SOME IP/RA INITIALLY...BUT THIS QUICKLY CHANGES
TO -SN WITH VIS RANGING BTWN 1-3SM...WHICH IS SIMILAR TO WHAT WL
HAPPEN ACRS OUR TAF SITES. OTHERWISE...BAND OF DEEPEST MOISTURE
AND BEST LIFT WL BE NORTHEAST OF OUR TAF SITES BY 00Z
TONIGHT...WITH MAINLY SCATTERED SNOW SHOWERS ANTICIPATED...AND
OCCASIONAL MVFR CONDITIONS POSSIBLE. SOUTHERLY WINDS WL CONT TO BE
GUSTY BTWN 15 AND 25 KNTS...BEFORE PRECIP ARRIVES. SFC COLD FRNT
NEAR KBUF WL CAUSE A WIND SHIFT TO THE SOUTHWEST/WEST THIS
EVENING...WITH SOME POTENTIAL HIGHER GUSTS OVERNIGHT. MVFR WITH
OCCASIONAL IFR CONDITIONS IN -SHSN ACTIVITY WL BE POSSIBLE
OVERNIGHT AT SLK...ELSEWHERE MVFR/VFR CONDITIONS ARE EXPECTED.
OUTLOOK 18Z WEDNESDAY THROUGH FRIDAY...
A VERTICALLY STACKED AREA OF LOW PRES AND THE ASSOCIATED CYCLONIC
UPSLOPE FLW WL RESULT IN OCCASIONAL SNOW SHOWER ACTIVITY FROM 18Z
WEDS THRU 06Z FRIDAY. THIS COMBINED WITH SEVERAL EMBEDDED S/W`S
WL PRODUCE PERIODS OF SNOW SHOWERS WITH OCCASIONAL IFR LIKELY AT
SLK/MPV AND MVFR CONDITIONS POSSIBLE AT BTV/MSS/RUT/PBG. THE
GREATEST CHC FOR IFR CONDITIONS AT BTV/RUT/PBG WL BE ON THURSDAY.
OTHERWISE...SFC RIDGE AND IMPROVING CONDITIONS ARE ANTICIPATED ON FRIDAY.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...EVENSON
NEAR TERM...JMG
SHORT TERM...EVENSON
LONG TERM...TABER
AVIATION...TABER
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1256 PM EST TUE FEB 19 2013
.SYNOPSIS...
A LARGE UPPER LEVEL TROUGH OF LOW PRESSURE WILL MOVE EAST FROM THE GREAT
LAKES REGION TODAY AND BE SLOW TO CLEAR OUR AREA OVER THE NEXT COUPLE
OF DAYS. AS A RESULT...EXPECT UNSETTLED WEATHER WITH LIGHT RAIN OR SNOW
DEVELOPING THIS AFTERNOON AND CONTINUING AS SNOW SHOWERS LATER TONIGHT.
SOME MINOR SNOW ACCUMULATIONS ARE EXPECTED. MORE SNOW SHOWERS ARE EXPECTED
WEDNESDAY THROUGH THURSDAY...ESPECIALLY OVER THE MOUNTAINS...WHERE SOME
SNOW ACCUMULATIONS ARE EXPECTED.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
AS OF 1223 PM EST TUESDAY...VERY MINOR UPDATES TO HOURLY
TEMPERATURES AND SFC DEWPOINTS INTO EARLY EVENING PER LATEST
OBSERVATIONAL DATA. READINGS ALL OVER THE PLACE DEPENDING ON
LOCALE AND/OR DEGREE OF MIXING...RANGING FROM THE UPPER 20S TO THE
MID 40S. STILL LOOKING AT LIGHT RAIN/SNOW DEVELOPING ACROSS OUR
NRN NY COUNTIES THIS AFTERNOON...AND INTO VERMONT LATE OR BY EARLY
EVENING AS COLD FRONT ACROSS WESTERN NY STATE MAKES ITS WAY EAST.
REST OF FCST REMAINS IN GOOD SHAPE. ENJOY YOUR AFTERNOON.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH THURSDAY/...
AS OF 333 AM EST TUESDAY...DRY SLOT ASSOCIATED WITH THE UPPER LOW
WILL MOVE INTO THE AREA TONIGHT AND THIS WILL HELP BRING AN END TO
MOST OF THE PRECIPITATION AFTER MIDNIGHT. SOME LINGERING SNOW
SHOWERS ARE EXPECTED OVER THE MOUNTAINS AND PARTS OF THE SOUTHERN
SAINT LAWRENCE VALLEY WHERE SOME LAKE EFFECT SNOW MAY DEVELOP OFF
OF LAKE ONTARIO AND MOVE INTO THE AREA. MOST LOCATIONS SHOULD SEE
A DUSTING TO 2 INCHES OF SNOW TONIGHT WITH SLIGHTLY HIGHER AMOUNTS
IN THE MOUNTAINS. THE UPPER LOW MOVES ACROSS THE AREA ON WEDNESDAY
AND REACHES NOVA SCOTIA BY THURSDAY. FAVORABLE NORTHWEST FLOW
ALOFT DEVELOPS WITH THIS SCENARIO. THUS LOOKING AT ISOLATED TO
SCATTERED SNOW SHOWERS IN THE LARGER VALLEYS WEDNESDAY THROUGH
THURSDAY AND NUMEROUS SNOW SHOWERS FOR THE MOUNTAINS. COULD SEE
ANYWHERE FROM 1 TO 4 INCHES OF NEW SNOW IN THE MOUNTAINS BY LATE
IN THE DAY ON THURSDAY. LOOK FOR A COOLING TREND THROUGH MUCH OF
THE PERIOD. HIGH TEMPERATURES WILL STILL BE AROUND NORMAL ON
WEDNESDAY...BUT WILL BE SEVERAL DEGREES BELOW NORMAL BY THURSDAY.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 333 AM EST TUESDAY...UPSLOPE SNOW SHOWERS ONGOING AT THE BEGINNING
OF THURSDAY NIGHT...BUT WINDING DOWN TOWARDS FRIDAY MORNING. FRIDAY
AND THE FIRST PART OF FRIDAY NIGHT WILL FEATURE QUIET WEATHER WITH
SURFACE HIGH PRESSURE IN CONTROL AND UPPER LEVEL RIDGE OVER THE REGION
AS WELL. A PAIR OF LOW PRESSURE SYSTEMS WILL THEN IMPACT THE NORTH COUNTRY
WITH THE WEAKER LOW PASSING NORTH OF OUR FORECAST AREA...AND THE STRONGER
LOW WELL OFF THE COAST. ECMWF BRINGS NORTHERN STREAM LOW ACROSS OUR
FORECAST AREA...MERGING WITH THE SOUTHERN STREAM LOW. GFS KEEPS THE
LOWS SEPARATE. HARD TO SAY AT THIS POINT HOW MUCH OUR REGION WILL BE
IMPACTED...IF AT ALL. AT THIS POINT HAVE MENTIONED CHANCE FOR SOME RAIN
AND SNOW SHOWERS...MAINLY SATURDAY NIGHT. SURFACE HIGH PRESSURE RIDGES
BACK INTO THE NORTH COUNTRY FOR MONDAY. THEN ANOTHER LOW PRESSURE SYSTEM
APPROACHES THE AREA FOR THE MID WEEK TIME FRAME. FAIRLY ACTIVE PERIOD...THOUGH
NO SIGNIFICANT PRECIPITATION EVENTS TO TALK ABOUT. TEMPERATURES WILL
RUN ABOVE NORMAL THROUGH THE ENTIRE EXTENDED FORECAST PERIOD.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
THROUGH 18Z WEDNESDAY...CNRT RADAR SHOWS A BAND OF MIXED PRECIP
MOVING TWD NORTHERN NY ATTM. DWPTS AHEAD OF THIS PRECIP ARE VERY
DRY...SO LEADING EDGE IS VIRGA AND NOT REACHING THE GROUND. IN
ADDITION...EXPECT THIS PRECIP TO COOL THE COLUMN ENOUGH TO SUPPORT
A RAIN CHANGING TO SNOW MIXTURE...ESPECIALLY AT SLK/MPV WITH
OCCASIONAL IFR LIKELY. BASED ON HRRR AND LATEST RADAR
TRENDS...THINKING IFR CONDITIONS WL ARRIVE IN SLK/MSS BY
19Z...WITH MVFR AT PBG/BTV/RUT BTWN 20-21Z...AND AFT 21Z AT MPV.
UPSTREAM OBS SHOW SOME IP/RA INITIALLY...BUT THIS QUICKLY CHANGES
TO -SN WITH VIS RANGING BTWN 1-3SM...WHICH IS SIMILAR TO WHAT WL
HAPPEN ACRS OUR TAF SITES. OTHERWISE...BAND OF DEEPEST MOISTURE
AND BEST LIFT WL BE NORTHEAST OF OUR TAF SITES BY 00Z
TONIGHT...WITH MAINLY SCATTERED SNOW SHOWERS ANTICIPATED...AND
OCCASIONAL MVFR CONDITIONS POSSIBLE. SOUTHERLY WINDS WL CONT TO BE
GUSTY BTWN 15 AND 25 KNTS...BEFORE PRECIP ARRIVES. SFC COLD FRNT
NEAR KBUF WL CAUSE A WIND SHIFT TO THE SOUTHWEST/WEST THIS
EVENING...WITH SOME POTENTIAL HIGHER GUSTS OVERNIGHT. MVFR WITH
OCCASIONAL IFR CONDITIONS IN -SHSN ACTIVITY WL BE POSSIBLE
OVERNIGHT AT SLK...ELSEWHERE MVFR/VFR CONDITIONS ARE EXPECTED.
OUTLOOK 18Z WEDNESDAY THROUGH FRIDAY...
A VERTICALLY STACKED AREA OF LOW PRES AND THE ASSOCIATED CYCLONIC
UPSLOPE FLW WL RESULT IN OCCASIONAL SNOW SHOWER ACTIVITY FROM 18Z
WEDS THRU 06Z FRIDAY. THIS COMBINED WITH SEVERAL EMBEDDED S/W`S
WL PRODUCE PERIODS OF SNOW SHOWERS WITH OCCASIONAL IFR LIKELY AT
SLK/MPV AND MVFR CONDITIONS POSSIBLE AT BTV/MSS/RUT/PBG. THE
GREATEST CHC FOR IFR CONDITIONS AT BTV/RUT/PBG WL BE ON THURSDAY.
OTHERWISE...SFC RIDGE AND IMPROVING CONDITIONS ARE ANTICIPATED ON FRIDAY.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...EVENSON
NEAR TERM...JMG
SHORT TERM...EVENSON
LONG TERM...NEILES
AVIATION...TABER
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1255 PM EST TUE FEB 19 2013
.SYNOPSIS...
COLDER AIR WILL MOVE INTO THE REGION TODAY. HIGH PRESSURE WILL
BUILD ACROSS THE AREA TONIGHT THROUGH THURSDAY. AN ELEVATED WARM
FRONT WILL APPROACH THE AREA THURSDAY NIGHT...BRINGING WITH IT A
WINTRY MIX OF PRECIPITATION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SYNOPTIC SCALE PCPN HAS PUSHED EAST OF THE REGION THIS MORNING. WE
WILL FIND OURSELVES IN POST FRONTAL CAA FOR THE REMAINDER OF THE
DAY. LOW LEVEL MOISTURE LOCATED WITHIN THE DENDRITIC GROWTH ZONE
COMBINED WITH STEEPENING LOW LEVEL LAPSE RATES WILL BRING A CHANCE
OF SNOW SHOWERS TO THE REGION...WITH THE GREATEST CHANCE ACROSS THE
NRN ZONES. SNOW AMOUNTS WILL BE LIGHT. THERE HAS BEEN A CONCERN
ABOUT WIND AND WIND GUSTS AS A TIGHT PRESSURE GRADIENT REMAINS.
LATEST MOMENTUM TRANSFER TECHNIQUES SUGGEST WIND GUSTS SHOULD STAY
IN THE 30 TO 35 KNOT RANGE ACROSS THE NORTH AND 25 TO 30 ACROSS
THE SOUTH...SO WILL CONTINUE TO HIGHLIGHT THIS IN THE HWO AND
PERHAPS A SPS PRODUCT. HAVE SLOWED DOWN THE CLEARING ACRS THE SW
INTO THIS EVENING AS LOW LEVEL MOISTURE IS EXPECTED TO LINGER
LONGER.
AS FOR TEMPERATURES...HAVE SIDED MORE WITH THE LATEST RAP WHICH
HAS TEMPERATURES SLOWLY FALLING THROUGHOUT THE DAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
COLD ADVECTION WITH GUSTY WINDS WILL CONTINUE INTO THE
EVENING...WITH A GRADUAL DECREASE IN WIND SPEEDS. ANY LINGERING
SNOW SHOWERS...MAINLY ACROSS THE NORTH...WILL BEGIN TO DIMINISH
DURING THE EVENING AS THE MOISTURE FEED FROM THE GREAT LAKES CUTS
OFF FROM OUR AREA AND HIGH PRESSURE NOSES ITS WAY EASTWARD.
SKIES WILL BEGIN TO CLEAR FROM SOUTHWEST TO NORTHEAST LATE
TONIGHT. THE COLDER AIRMASS MOVING INTO PLACE WILL ALLOW
TEMPERATURES TO DROP INTO THE TEENS ACROSS MOST OF OUR ZONES
TONIGHT.
THE RIDGE AXIS WILL FINALLY BE CENTERED FROM NORTH TO SOUTH ACROSS
THE OHIO VALLEY WEDNESDAY THROUGH THURSDAY. WITH THE EXCEPTION OF
ONGOING MOIST FLOW ACROSS THE LAKES BRINGING CLOUDS TO THE
NORTHEASTERN ZONES ON WEDNESDAY...SKIES WILL BE PARTLY CLOUDY DURING
THIS TIME PERIOD. TEMPERATURES WILL REMAIN SEASONABLY COOL UNDER
THIS RIDGE...WITH MEAN DAYTIME/NIGHTTIME TEMPERATURES RUNNING
ABOUT 10 DEGREES BELOW NORMAL.
THE ATTENTION THEN TURNS TO A STORM SYSTEM LIFTING NORTHWARD
ACROSS THE PLAINS THURSDAY NIGHT. MID LEVEL RIDGING WILL AMPLIFY
DOWNSTREAM OF THIS STORM THURSDAY NIGHT...BRINGING A DEVELOPING
ELEVATED WARM FRONT ACROSS THE REGION. PRECIPITATION WILL SPREAD
ACROSS THE REGION LATE THURSDAY EVENING AND OVERNIGHT THURSDAY
NIGHT...CONTINUING INTO FRIDAY MORNING. MODELS HAVE COME INTO
BETTER AGREEMENT ON THIS TIMING OVER THE PAST COUPLE OF RUNS.
WITH SURFACE HIGH PRESSURE PROVIDING COLD EASTERLY FLOW INTO OUR
AREA AS THE ELEVATED WARM FRONT LIFTS TOWARD THE OHIO
VALLEY...THERE WILL BE THE OPPORTUNITY FOR A PERIOD OF WINTRY
PRECIPITATION TO OCCUR. CURRENT INDICATIONS ARE THAT A SUFFICIENTLY
DEEP WARM LAYER WILL BE PRESENT ACROSS PARTS OF THE FORECAST AREA
TO ALLOW FOR EITHER SLEET OR FREEZING RAIN TO OCCUR AT THE SURFACE
DURING THE OVERNIGHT HOURS THURSDAY NIGHT. THERE WILL BE A
TRANSITION ZONE BETWEEN THE SHALLOWER WARM LAYER ACROSS THE
NORTH...WHERE MOSTLY SLEET WILL BE POSSIBLE...TO THE CENTRAL
ZONES...WHERE MOSTLY FREEZING RAIN WILL BE POSSIBLE...AND THE
SOUTH WHERE SURFACE TEMPERATURES WILL BE ABOVE FREEZING...YIELDING
RAIN. THIS FORECAST IS BASED ON CURRENT MODEL TRENDS AT 60 HOURS
OUT...THEREFORE MORE ADJUSTMENTS WILL BE ON THE WAY AS THE TIME
DRAWS NEARER FOR THIS STORM SYSTEM...AND SUBSEQUENT MODEL RUNS
COME IN. WILL CONTINUE TO HIGHLIGHT THIS SYSTEM IN THE HWO FOR THE
TIME BEING.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
BEST LIFT AND QPF ARE STILL FORECAST TO LIFT N OF THE REGION ON
FRIDAY...AS A WRMFNT GRADUALLY BRINGS IN WARMER AIR ON FRI.
AS MENTIONED YESTERDAY...SECONDARY SYSTEM THAT WAS LIFTING ACROSS
THE SE U.S. OVER THE WEEKEND HAS TRENDED NWD FOR FRI NGT INTO SAT...
SO INTRODUCED CHC POPS FOR THE SE COUNTIES. RIGHT NOW THE PCPN TYPE
LOOKS LIKE RAIN. HIGH PRESSURE LOOKS LIKE IT WILL FINALLY BUILD IN
FOR SUNDAY. ANOTHER CDFNT IS FORECAST TO SWING INTO THE OH VALLEY
MONDAY...BUT THE GFS AND ECMWF ARE SHOWING DIFFERENCES...SO RIGHT
NOW JUST HAVE A MENTION OF CHANCE POPS FOR MONDAY.
THE COOL SE FLOW ON THU WILL KEEP HIGHS IN THE 30S. LOWS THU NGT IN
THE STORM SHOULD RANGE FROM THE MID 20S IN THE N TO LOWER 30S IN NRN
KY. HIGHS FRIDAY SHOULD MAKE THE 40S AS THE REGION GETS WARM
SECTORED. SOME LOCATIONS IN THE NRN KY MIGHT SEE 50S. EXPECT 40S
OVER THE WEEKEND FOR HIGHS WITH LOWS IN THE UPPER 20S TO LOWER 30S
SATURDAY MORNING AND 25 TO 30 SUNDAY MORNING. HIGHS SHOULD BEGIN TO
WARM FOR SUNDAY AND MONDAY REACHING THE MID 40S TO MID 50S BY MONDAY.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
COLD UPPER LEVEL LOW ACROSS THE GREAT LAKES WILL MOVE SLOWLY OFF
TO THE EAST THROUGH THE TAF PERIOD. LOW LEVEL MOIST CYCLONIC FLOW
WILL GRADUALLY BECOME DRIER AND ANTICYCLONIC BY THE END OF THE TAF
PERIOD.
LOW LEVEL MOISTURE COMBINED WITH AN EMBEDDED DISTURBANCE WILL
RESULT IN FLURRIES AND A FEW SNOW SHOWERS THROUGH 00Z.
THEREAFTER...WE SHOULD SEE A DECREASE IN COVERAGE AS THE DISTURBANCE
MOVES EAST AND SHALLOW INSTABILITY DECREASES. CEILINGS FOR THE
MOST PART WILL BE MVFR WITH SOME MVFR VSBYS IN THE SNOW SHOWERS.
MODELS ARE GIVING MIXED SIGNALS AS TO HOW FAST SKIES WILL CLEAR
AND/OR PARTIALLY CLEAR FROM THE SW TO THE NE OVERNIGHT AND WHETHER
ANOTHER BATCH OF STRATOCUMULUS WILL FORM ACRS THE NORTH AND SETTLE
IN TOWARD MORNING. EITHER WAY...STILL WOULD THINK CEILINGS WOULD
REMAIN MVFR AND ABOVE 2000 FEET.
OUTLOOK...A WINTRY MIX IS LIKELY TO OCCUR THURSDAY NIGHT INTO
FRIDAY MORNING WITH SOME SLEET AND ICE ACCUMULATION POSSIBLE. IN
ADDITION MVFR CEILINGS AND VISIBILITIES WILL BE LIKELY WITH A
PERIOD OF IFR CONDITIONS POSSIBLE. MVFR CEILINGS MAY CONTINUE
THROUGH FRIDAY NIGHT AND INTO SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...LATTO
NEAR TERM...HICKMAN
SHORT TERM...LATTO
LONG TERM...HICKMAN
AVIATION...JGL
AREA FORECAST DISCUSSION
NWS MEDFORD OR
922 AM PST TUE FEB 19 2013
.DISCUSSION...THERE ARE TWO MAIN ITEMS OF FOCUS WITH THE FORECAST.
THE FIRST IS THE AMOUNT AND LOCATION OF SNOW SHOWERS THAT WILL
OCCUR DURING THE REMAINDER OF TODAY INTO THE EARLY EVENING. THE
SECOND IS THE STRENGTH AND TIMING OF A COLD FRONT AND POST-FRONTAL
SHOWERS FROM LATE FRIDAY INTO EARLY SATURDAY. WINTER WEATHER
ADVISORIES ARE IN EFFECT FOR MUCH OF THE AREA THROUGH 4 PM. THE
MAJORITY OF PRECIPITATION WILL OCCUR THROUGH NOON THEN SNOW
SHOWERS WILL GRADUALLY TAPER OFF INTO AROUND 7 PM. THE SNOW LEVEL
IS NEAR 1500 FEET THIS MORNING AND WILL RISE TO 2000 TO 2500 FEET
WITH THE DAY-TIME HEATING. THE RECENTLY ARRIVED 12Z NAM AND 12Z
GFS ARE IN LINE WITH THE CURRENT FORECAST.
THERE WILL ALSO BE A WEAK FRONTAL SYSTEM WEDNESDAY NIGHT INTO
EARLY THURSDAY MORNING WHICH WILL LIKELY PRODUCE LESS THAN AN INCH
OF SNOW.
THE FOLLOWING SYSTEM LATE FRIDAY INTO SATURDAY COULD BE THE
STRONGEST OF THE WEEK. BUT THE 12Z GFS SOLUTION BEARS SOME
SIMILARITY TO WHAT HAS OCCURRED THIS MORNING. THIS INCLUDES A
TROUGH TRACKING SOUTHEAST WITH A FOCUS FOR THE PRECIPITATION ON
THE WEST SIDE OF THE CASCADES.
THE CURRENT LONGWAVE PATTERN LOOKS TO PERSIST THROUGH DAY 7 WITH
AN ADDITIONAL WEAK FRONTAL SYSTEM SUNDAY NIGHT INTO MONDAY.
&&
.AVIATION...A MIX OF MVFR/VFR CEILINGS ACROSS THE AREA THIS
MORNING WITH LOCAL IFR/MOUNTAIN OBSCURATIONS IN HEAVIER SHRA/SHSN.
ISOLATED THUNDERSTORMS ARE POSSIBLE JUST ABOUT ANYWHERE WEST OF
THE CASCADES THROUGH THIS AFTERNOON, BUT THE BETTER CHANCE WILL BE
ALONG THE COAST. SHOWERS WILL DIMINISH ACROSS THE AREA LATER THIS
AFTERNOON AND EVENING AS LOW PRESSURE MOVES SOUTHWARD INTO
CALIFORNIA. EXPECT MIXED MVFR/VFR CEILINGS TO PREVAIL OVERNIGHT.
SPILDE
&&
.PREV DISCUSSION... /ISSUED 237 AM PST TUE FEB 19 2013/
DISCUSSION...COOLING CLOUD TOPS AT THE LEADING EDGE OF THE UPPER
COLD POOL ARE MOVING ONSHORE NOW AS A VIGOROUS UPPER LOW SPINS ITS
WAY INTO OUR AREA. SHOWERS WILL INCREASE IN COVERAGE AND INTENSITY
OVER THE COAST AND INTO INTERIOR WEST SIDE SECTIONS THROUGH DAWN.
SURFACE TEMPERATURES ARE CURRENTLY PERILOUSLY CLOSE TO COLD ENOUGH
FOR SNOW IN MANY LOCATIONS, BUT BOTH THE NAM AND RAP FORECAST
SOUNDINGS MAINTAIN A LAYER OF ABOVE FREEZING TEMPERATURES THROUGH
THE MORNING. WILL BE FORCING A RAIN/SNOW MIX INTO THE WEATHER
GRIDS THIS MORNING OVER ELEVATIONS ABOVE 1000 FEET, BUT AM NOT
EXPECTING ANY ACCUMULATION, IN FACT, IT MAY BE ALL RAIN.
THE GOING WINTER WEATHER HEADLINES LOOK OK TO CONTINUE, ESPECIALLY
OVER THE KALMIOPSIS AND WESTERN SISKIYOU COUNTY AS THE MODELS
BRING A SLUG OF MOISTURE INTO THE MOUNTAINS THERE TODAY. ON THE
EAST SIDE, IT`S A BIT MORE TENUOUS. UPSLOPE SNOW WILL CONTINUE IN
THE WARNERS, BUT SNOW OVER THE VALLEYS WILL BE MUCH LIGHTER WITH
MINIMAL IMPACTS. THE ADVISORIES ARE MOSTLY CONFINED TO THE
MOUNTAINS ANYWAY, SO WILL LET THEM RIDE. THE OTHER ASPECT OF
TODAY`S SYSTEM IS THE INSTABILITY, WHICH LOOKS TO BE PRETTY GOOD,
ESPECIALLY OVER THE WATERS. THE CENTER OF THE UPPER COLD POOL (500
MB TEMPS OF -36C) MOVES OVER THE RELATIVELY WARMER WATERS THIS
MORNING AND THEN INTO NW CALIFORNIA THIS AFTERNOON. AS A RESULT,
WE COULD SEE SOME LIGHTNING OVER THE WATERS AND IMMEDIATE COAST.
SIMILAR INSTABILITY WILL ALSO BE PRESENT INLAND, AND WHILE THE LOW
LEVELS WILL PROBABLY BE TOO COOL TO PRODUCE THE SORT OF UPDRAFT
NEEDED FOR LIGHTNING TODAY, I DECIDED IT WAS WORTH MENTIONING OVER
THE CASCADES AND WEST SIDE.
THIS SYSTEM MOVES INLAND TONIGHT WITH SHOWERS DECREASING QUICKLY.
WE STAY IN COOL NW FLOW THROUGH WEDNESDAY THEN ANOTHER SYSTEM
BRINGS PRECIPITATION AND LOW SNOW LEVELS WEDNESDAY NIGHT INTO
THURSDAY. THIS SYSTEM IS WEAKER AND MUCH LESS WET, SO I DOUBT
HEADLINES WILL BE NECESSARY.
THE BIGGER EVENT LOOKS TO BE ON TAP FOR FRIDAY NIGHT INTO
SATURDAY. AS OF NOW, THIS SYSTEM LOOKS TO BE THE WETTEST, COLDEST
AND WINDIEST WE`VE SEEN IN SOME TIME. THE MOUNTAINS AND EAST SIDE
WILL ALMOST CERTAINLY GET SIGNIFICANT SNOW WITH THIS ONE. IT WILL
BE COLD ENOUGH FOR SNOW DOWN INTO THE LOWER VALLEYS ON THE BACK
SIDE, BUT AS ALWAYS IT WILL COME DOWN TO WHETHER THERE IS ENOUGH
PRECIPITATION LEFT WHEN THE COLD AIR ARRIVES. IT`S TOO EARLY TO
SAY FOR SURE, BUT EVERYONE SHOULD JUST BE AWARE THAT LOW ELEVATION
SNOW IS POSSIBLE FRIDAY NIGHT INTO SATURDAY. I WOULD EXPECT WINTER
AND POSSIBLY WIND HEADLINES WITH THIS SYSTEM.
YET ANOTHER SYSTEM IS SLATED FOR SUNDAY NIGHT INTO MONDAY AS THE
PROGRESSIVE NORTHWEST FLOW PATTERN CONTINUES. -WRIGHT
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
ORZ031.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON ABOVE 2500
FEET FOR FOR ORZ024.
CA...WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
CAZ085.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON ABOVE 2500
FEET FOR FOR CAZ082-083.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON ABOVE 2500
FEET FOR FOR CAZ080.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL
2 AM PST FRIDAY FOR PZZ350-356-370-376.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 10 AM PST THIS MORNING FOR
PZZ370.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM PST THIS AFTERNOON FOR
PZZ376.
$$
DW/NSK
AREA FORECAST DISCUSSION
NWS MIDLAND/ODESSA TX
323 PM CST TUE FEB 19 2013
.DISCUSSION...
WV IMAGERY SHOWS THE UPPER TROUGH ALONG THE WEST COAST NEAR THE
OR/CA BORDER...TRANSITIONING FLOW ALOFT OVER WEST TEXAS/SE NM FROM
ZONAL TO SW AS IT PUSHES THE RIDGE EAST. W/IN THIS FLOW ALOFT IS A
THICK PLUME OF STR MSTR...PUTTING THE KIBOSH ON AFTERNOON HIGHS AND
WINDS OUT WEST. BUFFER AND LATEST RUC SOUNDINGS AT KGDP INDICATE
MUCH LESS MIXING AND HEAVIER CLOUD COVER...SO WE/LL CANCEL THE
CURRENT WIND WARNINGS/ADVISORIES THERE FOR THE AFTERNOON PACKAGE.
IN ITS PLACE...WE/LL INCREASE POPS OVER MUCH OF THE AREA. SHORT
RANGE MODELS ARE ALL CONSISTENT IN BRINGING A SHORTWAVE THRU THE
NORTHERN HALF OVER THE CWA OVERNIGHT...MAINLY NORTH OF I-10/20 UNDER
A NAM-ADVERTISED LFQ OF A H2 125+KT JET. AREA RADARS ALREADY SHOW
SHRA HAS DEVELOPED S OF KELP. FORECAST SOUNDINGS STILL SHOW FAIRLY
DRY SUBCLOUD LAYERS...SO QPF WILL BE LIGHT.
WEDNESDAY...LATEST MODELS HAVE SLOWED THE UPPER TROUGH FROM 24 HRS
AGO...AND BRING IT TO CENTRAL AZ BY 00Z THURSDAY. H7 PRESSURE
GRADIENT INCREASES TO 60M/150NM OVER THE GUADALUPES BY 18Z
WEDNESDAY...W/SFC GRADIENTS INCREASING AFTER 00Z THURSDAY AS A SFC
TROUGH MOVES SOUTH OF THE AREA...AND A LEESIDE SFC TROUGH SINKS INTO
THE SOUTH PLAINS THURSDAY AFTERNOON. AS THE UPPER TROUGH EJECTS
NE. HIGH WINDS WILL BE POSSIBLE THRU THE GUADALUPES FROM WED
AFTERNOON THRU THURSDAY...AND WE/LL ISSUE A WARNING TO COVER THIS
THRU THEN. ELSEWHERE...ADVISORIES WILL BE ISSUED FOR THE ADJACENT
PLAINS...AND FOR THE MTNS SOUTH. BLDU WILL STILL BE
POSSIBLE...DESPITE ANY QPF. W/THIS INCREASED SW FLOW...AND DESPITE
CLOUD COVER/COOLER TEMPS...RH/S OUT WEST SHOULD STILL REACH CRITICAL
LEVELS BY THE AFTERNOON. EAST OF THIS...INSTABILITY WILL BEGIN
INCREASING IN BETTER MOISTURE OVER THE EASTERN ZONES. FORECAST
SOUNDINGS SHOW A CAP...BUT A SHORTWAVE/LIFT AHEAD OF THE TROUGH MAY
BE SUFFICIENT ENOUGH TO KICK OFF A THUNDERSTORM OR TWO DURING THE
LATE MORNING/AFTERNOON. BY 00Z THURSDAY...MODELS SHARPEN UP A
DRYLINE MID-CWA...W/A WARM FRONT AND EVEN THE HINT OF A TRIPLE POINT
EAST. FORECAST SOUNDINGS LOSE THE CAP WEDNESDAY EVENING...FOR
THUNDERSTORM DEVELOPMENT ALONG AND EAST OF THE DRYLINE...W/BEST
CHANCES OVER THE UPPER CONCHO VALLEY. STILL NOT READY TO PULL THE
TRIGGER ON MENTIONING SEVERE STORMS YET...AND WOULD LIKE TO SEE
BETTER MID-LVL LRS. FORECAST SOUNDINGS CONTINUE TO INDICATE 0-6KM
BULK SHEAR OF 70KTS ALONG THE DRYLINE...AND ANY STORMS THAT DO
DEVELOP SHOULD MOVE EAST OUT OF THE AREA AT 40+KTS. THURSDAY INTO
THE EXTENDED CONTINUES TO LOOK DRY AND WINDY. W/THE EJECTION OF THE
UPPER TROUGH...THE ECMWF/CMC BRING IN THE NEXT TROUGH FLAT/FAST
FRIDAY...WHILE THE SLOWER...DEEPER GFS ARRIVES SATURDAY. ALL THREE
MODELS FINISH OUT THE EXTENDED WITH A SERIES OF UPPER LEVEL SYSTEMS
BRUSHING NORTH OF THE AREA...SUGGESTING WIND AND FIRE WX WILL BE
CANDIDATES FOR CONCERN THRU MIDWEEK NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
ANDREWS TX 47 65 36 64 / 70 10 20 0
BIG SPRING TX 44 63 39 62 / 60 20 50 0
CARLSBAD NM 40 70 34 67 / 40 0 0 0
DRYDEN TX 48 67 45 67 / 10 0 0 0
FORT STOCKTON TX 48 76 40 63 / 10 0 0 0
GUADALUPE PASS TX 38 62 27 52 / 40 0 0 0
HOBBS NM 42 65 32 64 / 70 0 20 0
MARFA TX 30 68 25 52 / 10 0 0 0
MIDLAND INTL AIRPORT TX 46 64 38 61 / 50 10 20 0
ODESSA TX 48 67 37 63 / 50 10 20 0
WINK TX 46 74 37 65 / 50 0 10 0
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...FIRE WEATHER WATCH THURSDAY AFTERNOON FOR THE FOLLOWING ZONES...
GUADALUPE MOUNTAINS NP/LINCOLN NF/LNZ...SOUTHEAST
PLAINS/BLM ROSWELL/LNZ.
HIGH WIND WARNING FROM 11 AM WEDNESDAY TO 5 PM MST THURSDAY FOR
THE FOLLOWING ZONES... GUADALUPE MOUNTAINS OF EDDY COUNTY.
RED FLAG WARNING FROM NOON TO 6 PM MST WEDNESDAY FOR THE
FOLLOWING ZONES... GUADALUPE MOUNTAINS NP/LINCOLN NF/LNZ...
SOUTHEAST PLAINS/BLM ROSWELL/LNZ.
WIND ADVISORY FROM 11 AM TO 5 PM MST WEDNESDAY FOR THE FOLLOWING
ZONES... EDDY COUNTY PLAINS.
TX...FIRE WEATHER WATCH FROM THURSDAY AFTERNOON THROUGH THURSDAY
EVENING FOR THE FOLLOWING ZONES... ANDREWS...BORDEN...
CRANE...DAWSON...ECTOR...GAINES...GLASSCOCK...GUADALUPE
MOUNTAINS...HOWARD...LOVING...MARTIN...MIDLAND...PECOS...
REAGAN...REEVES COUNTY AND UPPER TRANS PECOS...UPTON...VAN
HORN AND HIGHWAY 54 CORRIDOR...WARD...WINKLER.
WIND ADVISORY FROM NOON WEDNESDAY TO 6 AM CST THURSDAY FOR THE
FOLLOWING ZONES... BIG BEND AREA...DAVIS/APACHE MOUNTAINS
AREA...MARFA PLATEAU.
HIGH WIND WARNING FROM 11 AM WEDNESDAY TO 5 PM MST THURSDAY FOR
THE FOLLOWING ZONES... GUADALUPE MOUNTAINS.
RED FLAG WARNING FROM 1 PM CST /NOON MST/ TO 7 PM CST /6 PM MST/
WEDNESDAY FOR THE FOLLOWING ZONES... DAVIS/APACHE MOUNTAINS
AREA...GUADALUPE MOUNTAINS...LOVING...MARFA PLATEAU...
PRESIDIO VALLEY...REEVES COUNTY AND UPPER TRANS PECOS...VAN
HORN AND HIGHWAY 54 CORRIDOR.
&&
$$
12/44