Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/24/13
AREA FORECAST DISCUSSION
NWS TAUNTON MA
204 AM EDT FRI MAR 22 2013
.SYNOPSIS...
LOW PRESSURE MOVING SOUTHEAST OF NANTUCKET WILL BRING A PERIOD OF
ACCUMULATING SNOW TO THE SOUTHEAST NEW ENGLAND COAST TONIGHT.
OTHERWISE...MAINLY DRY BUT CHILLY WEATHER FOR LATE MARCH WILL
CONTINUE THROUGH MOST OF NEXT WEEK. WILL HAVE TO KEEP A CLOSE EYE
ON A MID ATLANTIC STORM FOR SUN NIGHT/MON. ODDS FAVOR THE BULK OF
THE STORM PASSING TO OUR SOUTH...BUT STILL A LOW PROBABILITY IT
TRENDS NORTH AND BRINGS MORE SNOW TO THE REGION.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
200 AM UPDATE...
HAS MENTIONED IN PREV AFD HAVE UPGRADED ADV TO A WARNING FOR
SOUTHERN BRISTOL AND PLYMOUTH COUNTIES. HEAVY BAND OF SNOW THAT
WAS SITUATED OVER THOSE COUNTIES HAS SHIFTED TO OVER COASTAL
PLYMOUTH AND THE CANAL. EXPECT SNOW FALL RATES OF 1-2" PER HOUR
AND VSBYS REDUCED TO BELOW ONE HALF OF A MILE. ROADS WILL BECOME
QUICKLY SNOW COVERED. AM CONSIDERING UPGRADING THE WARNING ACROSS
EASTERN PLYMOUTH AND BARNSTABLE COUNTIES. LATEST WEBCAMS SHOW
SNOW COVERED ROADS AND HVY SNOW FALL WITHIN THE BANDS. ALTHOUGH
HAVE NOT RECEIVED ANY REPORTS...WOULD NOT BE SURPRISED IF OVER 6
INCHES WILL BE REPORTED BY MORNING.
IRONICALLY THE GFS MODEL HAS BEEN HANDLING THIS MESOSCALE FEATURE
BETTER THAN THE HI-RES AND THE NAM. THE HRRR IS ALSO DOING FAIRLY
WELL. IN FACT THE NAM DOESNT EVEN HAVE QPF FOR SE MASS RIGHT NOW!
THE 00Z MODELS ARE STILL SHOWING A GOOD AMOUNT OF LIFT AND
MOISTURE WITHIN THE SNOWGROWTH ZONE INTO THE MORNING SO HAVE
EXTENDED THE HAZARDS. DO NOT SEE ANY LARGE FEATURES THAT WILL
PUSH THESE BANDS OUT OF THE AREA ANY TIME SOON. INTERESTING TO SEE
THAT 850MB VAD WIND PROFILES ARE SHOWING GOOD CONVERGENCE WHERE
THE BAND HAS SET UP. BANDS WILL CONTINUE TO MOVE IN A MORE NNE
DIRECTION TO FOLLOW THE MID-LEVEL FLOW.
EXPECT A SLOW MORNING COMMUTE TO AREAS WITHIN THE HAZARDS RIGHT
NOW. ALTHOUGH FORECASTING 4-8 INCHES...ISOLATED HIGHER AMOUNTS ARE
POSSIBLE. THIS IS THE STRUGGLE OF TRYING TO PINPOINT THE EXACT
LOCATION OF THE BANDING FEATURE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
MID LEVEL TROUGH STAYS PRETTY WELL PUT OVER THE NORTHEASTERN U.S.
THROUGH FRIDAY. THIS...IN COMBINATION WITH THE SURFACE LOW IN THE
MARITIMES WILL ALLOW FOR SOME FLURRIES AND ISOLATED LIGHT SNOW
SHOWERS TO LINGER OVER THE CAPE AND ISLANDS AS WELL AS START UP
ACROSS THE NORTHWESTERN ZONES LATER IN THE AFTERNOON. THESE SHOULD
START TO COME TO AN END OVERNIGHT AS THE MID LEVEL LOW AND SURFACE
LOW LIFT TO THE NORTHEAST TAKING THE LIFT AND MOISTURE WITH IT.
TEMPERATURES WERE A BLEND OF BIAS CORRECTED MOS...WITH HIGH TEMPS
REACHING THE MID TO UPPER 30S TO LOW 40S AND LOW TEMPS IN THE 20S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
HIGHLIGHTS...
* UNSEASONABLY CHILLY WEATHER THROUGH NEXT WEEK
* NEED TO KEEP A CLOSE EYE ON A MID ATLANTIC STORM SUN NIGHT/MON
DETAILS...
THE OVERALL PATTERN WILL CONTINUE TO FEATURE A NEGATIVE AO/NAO WELL
INTO NEXT WEEK. THIS WILL RESULT IN LOWER THAN AVERAGE HEIGHT
FIELDS AND IN TURN BELOW NORMAL TEMPS IN OUR REGION. MUCH OF THE
PERIOD WILL FEATURE DRY NORTHWEST FLOW...SO THE STRONG MARCH SUN
SHOULD STILL BE ENOUGH TO PUSH HIGHS INTO THE UPPER 30S TO MIDDLE
40S MUCH OF THE TIME. THE LATEST MEX GUIDANCE APPEARS TOO MILD
THOUGH AS IT OFTEN TRENDS MORE TOWARDS CLIMATOLOGY IN THE LATER PERIODS.
THE MAIN THING TO WATCH IS THE TRACK OF A MID ATLANTIC STORM SUNDAY
NIGHT INTO MONDAY. MOST OF THE GUIDANCE HAS BEEN IN GOOD AGREEMENT
THAT THE MAIN AFFECTS FROM THIS STORM WILL PASS SOUTH OF OUR REGION.
THIS A RESULT OF VERY STRONG HIGH LATITUDE BLOCKING AND THE CLOSED
UPPER LEVEL LOW NEAR THE CANADIAN MARITIMES. HOWEVER...THIS STORM IS
STILL ABOUT 4 DAYS AWAY AND IT WOULDN/T TAKE MUCH OF A NORTHWARD
ADJUSTMENT TO GET US INTO AT LEAST SOME OF THE PRECIPITATION SHIELD.
IF THIS WERE TO OCCUR...MOST OF THE REGION WOULD BE COLD ENOUGH FOR
A SNOW EVENT. SO WHILE ODDS CURRENTLY FAVOR MORE OF A MISS/GLANCING
BLOW TO THE SOUTH...THERE REMAINS A LOW PROBABILITY FOR ACCUMULATING
SNOW SUNDAY NIGHT INTO MONDAY. LOW POPS WERE INCLUDED IN THE
FORECAST TO ACCOUNT FOR THIS POSSIBILITY.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...MODERATE CONFIDENCE EARLY THIS MORNING AND HIGH
CONFIDENCE AFTERWARDS.
MVFR TO IFR CONDITIONS ARE EXPECTED IN BANDS OF MODERATE TO HEAVY
SNOW SHOWERS ACROSS SOUTHEAST MA EARLY THIS MORNING. EXPECT
IMPROVING CONDITIONS BY THE MID-MORNING HOURS. VFR CONDITIONS
WILL PERSIST ELSEWHERE. DIURNAL CU WILL DEVELOP TOMORROW AS NW
WINDS MAY GUST TO 20-25 KTS BY THE AFTERNOON...LASTING THROUGH
THE OVERNIGHT HOURS.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SATURDAY AND SUNDAY...HIGH CONFIDENCE IN MAINLY VFR CONDITIONS.
NORTHWEST WIND GUSTS OF 25 TO 35 KNOTS EXPECTING DURING THE DAY
SAT...BUT MUCH LESS WIND ON SUN.
SUNDAY NIGHT AND MONDAY...LOW CONFIDENCE. MVFR-IFR CONDITIONS IN
SNOW WOULD OCCUR ONLY IF STORM ENDS UP TRACKING FURTHER NORTH THAN
CURRENT MODELS INDICATE.
TUESDAY...MODERATE TO HIGH CONFIDENCE. MAINLY VFR CONDITIONS.
&&
.MARINE...
MODERATE TO HIGH CONFIDENCE THROUGH FRIDAY NIGHT.
SEAS BUILD WITH THE PASSAGE OF A SURFACE LOW PRESSURE SOUTH AND EAST
OF THE COASTAL WATERS. 5 TO 6 FOOT SEAS ARE EXPECTED ON THE OUTER
WATERS BY FRIDAY MORNING AND 6 TO 8 FOOT SEAS BY FRIDAY NIGHT.
NORTHEASTERLY WINDS WILL SHIFT TO THE WEST AS THEY INCREASE TO
AROUND 25 KTS. SMALL CRAFT ADVISORIES ARE UP FOR THE SOUTHEASTERN
OUTER WATERS THROUGH FRIDAY AFTERNOON. THESE WILL LIKELY NEED TO BE
EXTENDED INTO FRIDAY NIGHT FOR MORE OF THE WATERS.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SATURDAY AND SATURDAY NIGHT...HIGH CONFIDENCE IN STRONG SCA WIND
GUSTS FROM THE NORTHWEST IN THE COLD AIR ADVECTION PATTERN. LOW
PROBABILITY FOR A PERIOD OF MARGINAL GALE FORCE WIND GUSTS.
SUNDAY...MODERATE TO HIGH CONFIDENCE. WINDS AND SEAS
SUBSIDING...BUT LINGERING SCA LIKELY NEEDED FOR AT LEAST THE MORNING.
SUNDAY NIGHT AND MONDAY...MODERATE CONFIDENCE. SHOULD SEE AT LEAST
SCA NORTHEAST WIND GUSTS DEVELOP LATE SUN NIGHT/MON AS LOW PRESSURE
PASSES SOUTH OF THE WATERS. THERE IS A LOW PROBABILITY FOR A PERIOD
OF GALE FORCE WIND GUSTS IF THE STORM TRACK ENDS UP FURTHER NORTH
THAN CURRENT MODELS INDICATE.
TUESDAY...MODERATE CONFIDENCE. MARGINAL NORTHWEST SCA WIND GUSTS OF
20 TO 25 KNOTS ARE POSSIBLE IN THE COLD AIR ADVECTION PATTERN BEHIND
THE DEPARTING LOW PRESSURE SYSTEM.
&&
.CLIMATE...
NORMAL HIGH TEMP/NORMAL LOW TEMP
BOS 47 / 32
BDL 50 / 29
PVD 49 / 31
ORH 45 / 28
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...WINTER WEATHER ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
MAZ018-019-022-023.
WINTER STORM WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR
MAZ020-021.
NH...NONE.
RI...WINTER WEATHER ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
RIZ007.
MARINE...SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
ANZ254>256.
&&
$$
SYNOPSIS...FRANK/RLG
NEAR TERM...DUNTEN
SHORT TERM...RLG
LONG TERM...FRANK
AVIATION...FRANK/DUNTEN
MARINE...FRANK/RLG
CLIMATE...STAFF
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
940 PM EDT SAT MAR 23 2013
.DISCUSSION...
LATEST RAP ANALYSIS SHOWING THE DVLPG STORM SYSTEM OVER THE WRN
GOMEX GRADUALLY BCMG BETTER ORGANIZED UNDER THE INFLUENCE OF A 130KT
H30-H20 JET. AS THE SYSTEM TRACKS INTO THE DEEP SOUTH OVERNIGHT...IT
WILL COMBINE WITH A LARGE H100-H70 ANTICYCLONE CENTERED JUST E OF
THE SRN BAHAMAS TO MAINTAIN A STEADY DEEP LYR W/SW FLOW ACRS THE FL
PENINSULA.
UPSTREAM MOISTURE OVER THE SE GOMEX/FL STRAITS IS RATHER SPARSE. RAP
INDICATES H100-H70 MEAN RH AOB 60PCT OVER THE FL KEYS AND THE N
SHORE OF CUBA. MID LVL VORT FIELDS LOOK SPARSE AS WELL. DYNAMIC
SUPPORT IS SURPRISINGLY STRONG AS PENINSULA REMAINS UNDER THE
INFLUENCE OF THE ASCENDING RIGHT REAR QUAD OF A LARGE 120KT JET
MOVING OFF THE ATLC COAST. NEVERTHELESS...WITH DRY AIR ADVECTION
OCCURRING...CANNOT SEE ANY REASON TO KEEP POPS IN THE FCST MUCH
LONGER.
CONVECTIVE LINE OVER NE VOLUSIA EXTENDING OFFSHORE LOOKS TO BE THE
LAST GASP FOR THE OVERNIGHT PD. WILL UPDATE THE ZONE FCST TO REMOVE
PRECIP ONCE THE LAST CLUSTER MOVES OFFSHORE.
&&
.AVIATION...
THRU 24/04Z...PREVAILING VFR...LCL IFR CIGS/VSBYS IN ISOLD TSRAS
VCNTY KDAB. BTWN 24/04Z-24/08Z...IFR CIGS DVLPG ALL SITES...CONTG
THRU 24/13Z. BTWN 24/13Z-24/17Z...SW SFC WNDS INCRSG TO 18-22KTS
SUSTAINED WITH G25-30KTS...CIGS BCMG MVFR ALL SITES...IFR TSRAS
LIKELY N OF KISM-KTIX. AFT 24/17Z...CHC IFR TSRAS ALL SITES.
&&
.MARINE...
WARM FRONT BEGINNING TO STALL OVER THE FL PANHANDLE...RESULTING IN
A WIDE RANGE OF WIND SPEEDS/DIRECTIONS. LATEST OBS/SFC ANALYSIS SHOW
AREAS CLOSER TO THE FRONT (N OF CAPE CANAVERAL) WITH A LIGHT TO
GENTLE N-NE BREEZE...BCMG A MODERATE S-SW BREEZE S OF THE CAPE. SEAS
GENERALLY 2-3FT AREAWIDE. WINDS WILL FRESHEN OVERNIGHT...BCMG A
MODERATE TO FRESH S/SW BREEZE AREAWIDE AROUND DAYBREAK AS THE DVLPG
STORM SYSTEM OVER THE WRN GULF COAST CONSOLIDATES WHILE DRIFTING
INTO THE DEEP SOUTH. SEAS BUILDING TO 3-4FT NEARSHORE AND 4-5FT
OFFSHORE. NO SIG CHANGES NECESSARY.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...SMALL CRAFT ADVISORY FROM 11 AM SUNDAY TO 8 AM EDT TUESDAY FOR
COASTAL WATERS FROM FLAGLER BEACH TO VOLUSIA BREVARD COUNTY
LINE OUT 20 NM-COASTAL WATERS FROM VOLUSIA BREVARD COUNTY
LINE TO SEBASTIAN INLET OUT 20 NM-WATERS FROM FLAGLER BEACH
TO VOLUSIA BREVARD COUNTY LINE 20 TO 60 NM OFFSHORE-WATERS
FROM SEBASTIAN INLET TO JUPITER INLET 20 TO 60 NM OFFSHORE-
WATERS FROM VOLUSIA BREVARD COUNTY LINE TO SEBASTIAN INLET
20 TO 60 NM OFFSHORE.
SMALL CRAFT ADVISORY FROM 11 AM SUNDAY TO 4 AM EDT MONDAY FOR
COASTAL WATERS FROM SEBASTIAN INLET TO JUPITER INLET OUT 20
NM.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM/IMPACT WX...KELLY
AREA FORECAST DISCUSSION
NWS LINCOLN IL
907 PM CDT SAT MAR 23 2013
.DISCUSSION...
ISSUED 907 PM CDT SAT MAR 23 2013
WHILE THINGS WILL BE MOSTLY QUIET FOR THE NEXT SEVERAL HOURS
ACROSS CENTRAL AND SOUTHEAST ILLINOIS...A SIGNIFICANT EARLY SPRING
STORM IS STILL ON TRACK TO IMPACT THE AREA STARTING LATE TONIGHT
AND THROUGHOUT SUNDAY.
IT IS APPARENT THROUGH SURFACE OBS/SATELLITE LOOPS/00Z KILX
SOUNDING THAT THE LOCAL AIRMASS IS STILL PRETTY DRY AND WILL NEED
TO UNDERGO QUITE A BIT OF MOISTENING FOR SIGNIFICANT PRECIPITATION
TO OCCUR. A DRY NORTHEASTERLY FLOW FROM 800 MB TO THE SURFACE
SHOULD ALSO HELP TO LIMIT THE PRECIPITATION THREAT FOR A TIME. IN
ADDITION...THE UPPER LOW DRIVING THE STORM HAS ONLY RECENTLY
STOPPED DIGGING ACROSS THE SOUTHERN PLAINS...PER WATER VAPOR
LOOPS...AND IT WILL STILL TAKE SOME TIME TO GET HERE.
THE BULK OF THE FORECAST MODELS SUGGEST INCREASING WAA/ISENTROPIC
LIFT THROUGH THE NIGHT WILL HELP TO PROVIDE TOP DOWN MOISTENING...
ALLOWING MOST AREAS TO SEE LIGHT PRECIPITATION BY DAYBREAK SUNDAY.
HOWEVER...THE LATEST RUNS OF THE SHORT RANGE/HIGH RESOLUTION HRRR
AND RAP MODELS SUGGEST MUCH OF THE PRECIPITATION FALLING THROUGH
THE NIGHT WILL SIMPLY MOISTEN THE DRY AIR AND PRODUCE FAIRLY
MINIMAL PRECIPITATION AT THE SURFACE. THE HEAVIER SNOWFALL IS
STILL NOT EXPECTED TO ARRIVE UNTIL VERY LATE SUNDAY MORNING AND
THROUGH THE AFTERNOON.
THE LOW LEVEL THERMAL PROFILE IN THE 00Z KILX AND FORECAST
SOUNDINGS SUGGEST ENOUGH LOW LEVEL WARM AIR IN PLACE FOR THE
PRECIP TO START AS RAIN IN MANY AREAS. THE EVAPORATIVE COOLING DUE
TO THE DRY AIR/CONTINUED DRY LOW LEVEL FLOW SHOULD QUICKLY CHANGE
THE PRECIP OVER TO SNOW.
MOST OF FORECAST IS IN PRETTY GOOD SHAPE. HOWEVER...PLAN TO BACK
OFF ON POPS/PCPN AMOUNT A BIT TONIGHT BASED ON THE FACTORS
MENTIONED ABOVE. WILL NOT MAKE ANY HEADLINE ADJUSTMENTS AT THIS
TIME.
BAK
&&
.AVIATION...
ISSUED 650 PM CDT SAT MAR 23 2013
VFR CONDITIONS EXPECTED ACROSS THE CENTRAL ILLINOIS TERMINALS INTO
THE OVERNIGHT HOURS TONIGHT...BUT THEY SHOULD DEGRADE TO IFR LATE
TONIGHT/EARLY SUNDAY AS A STRONG STORM SYSTEM SPREADS SNOW INTO
THE REGION FROM THE SOUTHWEST. THERE WILL BE TWO HEAVIER WAVES OF
SNOWFALL...THE FIRST SHOULD OCCUR A FEW HOURS EITHER SIDE OF
SUNRISE SUNDAY...WITH THE SECOND OCCURRING SUNDAY AFTERNOON. WHILE
THERE MAY BE A BREAK LATER SUNDAY MORNING WHERE CONDITIONS BRIEFLY
IMPROVE ABOVE IFR...HAVE NOT INCLUDED THIS AT THIS TIME DUE TO THE
LINGERING UNCERTAINTY WITH RESPECT TO TIMING OR HOW MUCH
IMPROVEMENT WILL TAKE PLACE. NORTHEAST WINDS WILL PREVAIL THROUGH
THE PERIOD AS THE TERMINALS LIE TO THE NORTH/WEST OF THE MAIN
STORM TRACK. EXPECT WINDS TO BECOME QUITE GUSTY AT TIMES DURING THE
DAY SUNDAY WHICH IS LIKELY TO COINCIDE WITH THE HEAVIEST SNOWFALL
AND RESULT IN THE LOWEST VISIBILITIES.
BAK
&&
.PREV DISCUSSION...
ISSUED 255 PM CDT SAT MAR 23 2013
SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
THREAT FOR HEAVY WET SNOW OVER PORTIONS OF CENTRAL...EAST CENTRAL
AND SOUTHEAST ILLINOIS CONTINUES FOR SUNDAY THROUGH SUNDAY NIGHT.
MAJOR SPRING SNOW EVENT STARTING TO TAKE SHAPE OVER THE SOUTHERN
ROCKIES THIS AFTERNOON WITH PRECIP ALREADY BLOSSOMING WEST OF THE
MISSOURI RIVER IN THE MID LEVEL WARM ADVECTION/ISENTROPIC LIFT
REGION. AS THE AREA OF ENHANCED LIFT SHIFTS ENE INTO THE MIDWEST
LATER THIS EVENING...WE SHOULD SEE SOME RAIN AND SNOW DEVELOP TO
THE WEST OF THE MISSISSIPPI RIVER AND SPREAD EAST INTO WEST CENTRAL
ILLINOIS LATER THIS EVENING AND THEN SLOWLY TO THE EAST BY SUNDAY
MORNING. NAM-WRF CONTINUING TO DEPICT TWO SIGNIFICANT AREAS OF
LIFT WITH THIS STORM. THE INITIAL BAND OF LIFT/ISENT ASCENT PUSHES
ACRS THE AREA IN THE 06Z-15Z TIME FRAME...WITH A LULL IN THE MORE
INTENSE SNOWFALL AND THEN PICK UP AGAIN WITH THE SECOND AND MORE
CONCENTRATED AREA OF FORCING ASSOCIATED WITH THE CLOSED 500 MB LOW.
CROSS SECTIONS THROUGH THE HEART OF OUR CWA SHOWING THESE TWO DISTINCT
AREAS OF LIFT WELL WITH BOTH ASSOCIATED WITH DEEP MOISTURE AND
CONCENTRATED OMEGA IN THE FAVORED DENDRITIC ZONE. AS THE DEFORMATION
ZONE TRACKS ACRS THE REGION TOMORROW AFTERNOON AND EVENING ASSOCIATED
WITH THE MORE POTENT FORCING...THERE ARE A FEW AREAS OF NEGATIVE
EPV SHOWING UP ON THE CROSS SECTIONS JUST NORTH OF STL ENE TO JUST
SOUTH OF ROUTE 36 OVER CENTRAL IL. FORECAST SOUNDINGS ALSO SHOWING
A SMALL AREA OF MOST UNSTABLE CAPES IN THAT CORRIDOR AS WELL SUGGESTING
A CONTINUING THREAT FOR ISOLATED CONVECTION ASSOCIATED WITH THE HEAVIER
BURSTS OF SNOW. TROWAL SIGNATURE SHOWING UP ON THE 305K PRESSURE SURFACE
AS WELL SUNDAY EVENING WHICH WILL PROLONG THE SNOW EVENT ACROSS THE
EAST WITH ADDITIONAL ACCUMULATIONS POSSIBLE. NOT MUCH OF A THREAT FOR
BLOWING SNOW SUNDAY WITH SFC TEMPS AT OR ABOVE FREEZING...BUT THAT MAY
BE A DIFFERENT STORY SUNDAY NIGHT AS GUSTY NORTH TO NORTHWEST WINDS
AND COLDER TEMPERATURES BRING ABOUT AT LEAST A THREAT FOR SOME BLOWING
SNOW...ESP ACROSS THE NORTH AND EASTERN COUNTIES.
AS A RESULT...HAVE UPGRADED THE WATCH TO A WARNING FOR ALL AREAS EXCPT
ALONG AND NW OF THE ILLINOIS RIVER. HAD INITIALLY THOUGHT OF GOING
WITH AN ADVISORY FOR OUR SOUTHEAST COUNTIES...BUT BASED ON THE TRACK
OF THE CLOSED 850 AND 500 MB LOWS ON THE NAM-WRF AND SREF...THOUGHT
THE THREAT FOR ISOLD THUNDER SNOW...JUST NORTH OF THE RAIN-SNOW LINE...
WOULD BE ENHANCED. SO BUMPED UP THE SNOW NUMBERS IN SE IL WITH AMOUNTS
IN THE 5 TO 7 INCH RANGE. CARRIED THE WARNING INTO MONDAY MORNING ACRS
EAST CENTRAL IL BASED ON THE SLOWER TREND SHOWING UP ON MODELS THE PAST
FEW RUNS.
CYCLONIC FLOW IN THE WAKE OF THE DEPARTING STORM ON MONDAY AND MONDAY
NIGHT WILL YIELD SCATTERED SNOW SHOWERS OR FLURRIES ALONG WITH A
CONTINUATION OF THE UNSEASONABLY COLD TEMPERATURES FOR THE THIRD WEEK
OF MARCH.
LONG TERM...TUESDAY THROUGH SATURDAY...
THE CHILLY WEATHER WILL CONTINUE INTO TUESDAY AS THE UPPER LOW
SHIFTS TO THE EAST COAST...WITH 850 MB TEMPS LINGERING AROUND -10C.
HOWEVER...THE SECOND HALF OF THE WEEK WILL FEATURE SOME GRADUALLY
MODERATING AIR AS RIDGING SLOWLY BUILDS OVER THE WESTERN HALF OF THE
NATION. HIGHS CLOSER TO NORMAL FOR THIS TIME OF YEAR... I.E. 50S...
EXPECTED BY FRIDAY AND SATURDAY.
AFTER A SURFACE HIGH PRESSURE RIDGE SLOWLY MOVES THROUGH THE MIDWEST
WEDNESDAY AND WEDNESDAY NIGHT...NEXT FOCUS REMAINS WITH A SHORTWAVE
PASSING THROUGH LATE WEEK. LATEST ECMWF IS QUITE BULLISH WITH THE
PRECIP FRIDAY AND FRIDAY NIGHT...WHEREAS THE GFS IS ABOUT 12-18
HOURS FASTER WITH THIS. HAVE CONCENTRATED THE PRECIP CHANCES IN THE
GRIDS IN THE FRIDAY NIGHT TIME FRAME...ALTHOUGH CONFIDENCE IS NOT
ESPECIALLY HIGH AT THE MOMENT.
SHORT TERM...SMITH
LONG TERM....GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 1 AM SUNDAY TO 1 AM CDT MONDAY FOR
ILZ037-040>042-047>054-061-066-071.
WINTER STORM WARNING FROM 4 AM SUNDAY TO 7 AM CDT MONDAY FOR
ILZ038-043>046-055>057-062-063-067-068-072-073.
WINTER WEATHER ADVISORY FROM 1 AM SUNDAY TO 1 AM CDT MONDAY FOR
ILZ027>029-036.
WINTER WEATHER ADVISORY FROM 4 AM SUNDAY TO 7 AM CDT MONDAY FOR
ILZ030-031.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
506 PM CDT FRI MAR 22 2013
.DISCUSSION...
307 PM CDT
TONIGHT THROUGH SATURDAY...
ANTI-CYCLONIC FLOW WILL CONTINUE TO PROVIDE DRY WEATHER THROUGH
TONIGHT...HOWEVER WILL BEGIN TO LIFT NORTH SAT AHEAD OF A POTENT
WINTER WEATHER SYSTEM SET TO ARRIVE LATE SAT NIGHT. VISIBLE
IMAGERY THIS AFTERNOON CONTINUES TO DEPICT THE CHANNEL OF CIRRUS
AND MID-LVL CLOUDS SLIDING NORTHEAST FROM THE NORTHERN PLAINS
SOUTHEAST THROUGH CENTRAL TENNESSEE. ANOTHER CHANNEL OF CLOUDS WAS
SLOWLY DROPPING SOUTH ACROSS THE UPPER PENINSULA OF MI TO
NORTHEAST LOWER MI. SFC TEMPS HAVE WARMED THIS AFTERNOON ACROSS
NORTHERN IL INTO THE MID 30S ACROSS MANY AREAS...HOWEVER WITH THE
LIGHT FLOW AND WARMER SFC TEMPS INITIALLY ACROSS CHICAGO...A LAKE
BREEZE HAS FORMED AND SLOWLY PUSHING INLAND. THIS HAS RESULTED IN
SFC TEMPS ALONG THE IMMEDIATE SHORELINE COOLING. OVERNIGHT TONIGHT
SKIES SHOULD REMAIN RELATIVELY CLEAR...POSSIBLY JUST A THIN CIRRUS
DECK WILL SLIDE OVERHEAD. LCL HI-RES GUIDANCE HAS SUGGESTED AN
ARRIVAL OF A THIN STRATUS LAYER EARLY SAT MORNING ACROSS NORTHEAST
IL...WHICH COULD POSE SIGNIFICANT CHALLENGES WITH THE HIGH
FORECAST FOR SAT.
OVERNIGHT TEMPS WILL COOL INTO THE TEENS ACROSS THE REMAINING
SNOWPACK AREAS OF FAR NORTHERN/NORTHWEST IL...OTHERWISE TEMPS WILL
RADIATE INTO THE LOW/MID 20S. THE WARMEST AREAS MAY END UP BEING THE
AREAS ADJACENT TO LAKE MICHIGAN. WINDS WILL ALSO BE TURNING
NORTHEASTERLY OFF OF THE LAKE OVERNIGHT.
GUIDANCE CONTINUES TO FAVOR THE MID-LVL RIDGE AXIS PUSHING EAST OF
THE AREA SAT EVE...ALLOWING FOR ANOTHER DAY OF DRY WEATHER. ALTHOUGH
IT DOES APPEAR THAT WITH WINDS BECOMING NORTH/NORTHEAST...THE
CHANCES OF TEMPS WARMING FURTHER INTO THE UPR 30S TO LOW 40S LOOKS
MINIMAL. HAVE OPTED TO NUDGE TEMPS DOWN A COUPLE OF DEGREES INTO THE
MID/UPR 30S.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...
LATE SEASON WINTER STORM CONTINUES TO BE THE MAIN FOCUS FOR THE OHIO
VALLEY. AT THIS TIME THE ECMWF CONTINUES TO TAKE THE SYSTEM FURTHER
SOUTH...PULLING THE SNOW TOTALS FURTHER SOUTH INTO CENTRAL IL/IN FOR
THE ENTIRE EVENT. SREF PLUMES HAVE INDICATED THAT MANY LOCATIONS
ALONG AND SOUTH OF I-80 WILL SEE SEVERAL INCHES OF SNOWFALL FOR THE
EVENT...WITH A RANGE FROM 1 INCH TO POSSIBLE IN EXCESS OF 6 INCHES.
GUIDANCE CONTINUES TO SHOW CORRECTIONS ON THE PLACEMENT/INTENSITY OF
THIS SYSTEM...AS WELL AS THE FGEN LOCATION. THE 850MB LOW IS
CURRENTLY PROGGED TO SLIDE EAST FROM CENTRAL MO INTO SOUTHCENTRAL
IL/CENTRAL IN. THIS COULD PLACE THE BEST FGEN BAND ACROSS THE
SOUTHERN CWFA...MAINLY LIVINGSTON/FORD/IROQUOIS COUNTIES STRETCHING
EAST INTO NEWTON/JASPER/BENTON COUNTIES. WILL PROCEED TO POST A
WINTER STORM WATCH FOR THE THESE COUNTIES IN THE SOUTHERN CWFA.
ENSEMBLES HAVE CONTINUED TO SHOW SOME STRENGTHENING IN THE 850MB
EASTERLY U-WIND ANOMS SUN TO NEARLY 4 SIGMA...30-40KTS. ABUNDANT
MOISTURE WILL BE PICKED UP AHEAD OF THIS SYSTEM FROM THE WESTERN
GULF OF MEXICO...IN ADDITION THE ATMOSPHERE ACROSS CENTRAL IL/IN
DOES APPEAR TO BECOME UNSTABLE AT THE PEAK OF THE STORM. ADDING TO
THE POSSIBILITY OF THUNDER/LIGHTNING ACCOMPANYING THE SNOW. THIS
COULD EASILY ENHANCE THE SNOWFALL RATES IN THE 15-00Z SUN TIMEFRAME.
AT THIS TIME IT APPEARS THE BEST LOCATION FOR THIS WOULD OCCUR ALONG
THE FAR SOUTHERN SECTIONS OF FORD/IROQUOIS/LIVINGSTON COUNTIES SUN.
THE LARGEST CAVEAT IS THAT HIGH PRESSURE WILL BE LIFTING TO THE
NORTH OF THE REGION...WITH A TIGHTENING GRADIENT DEVELOPING ALONG
THE NORTHERN PERIPHERY OF THE SYSTEM. THIS SETUP WOULD MOST LIKELY
SHARPEN UP THE SNOW TOTALS FROM WHERE IT SNOWS TO SEVERAL
INCHES...GIVEN THE DRY NEAR SFC ENVIRONMENT. HOWEVER...COMPOUNDING
THIS IS THE FACT THAT THE POTENTIAL FOR LAKE EFFECT SNOW INCREASES
GIVEN HOW COLD THE ENVIRONMENT WILL BE. THERMAL DIFFERENTIALS FROM
THE LAKE SFC/850MB BECOMES FAVORABLE IN THE 12-15 DEG RANGE. SO HAVE
MAINTAINED THE FORMATION OF LAKE SNOW FOR FAR NORTHEAST IL SUN.
WITH THE THICKENING CLOUD COVER AND A COOL BREEZE FROM THE
NORTHEAST...TEMPS SUN MAY STRUGGLE TO WARM BEYOND THE LOW 30S.
CONFIDENCE IN TEMPERATURES...HIGH.
CONFIDENCE IN SNOWFALL...MEDIUM.
CONFIDENCE IN SNOW TIMING...MEDIUM.
MONDAY THROUGH THURSDAY...
500MB TROUGH AXIS CONTINUES TO PIVOT EAST TOWARDS THE EAST COAST
MON...WITH WEAK RIDGING BEGINNING TO FORM ACROSS THE PAC-NW. IT
APPEARS BEYOND MON THROUGH THE REMAINDER OF THE WEEKEND THE UPSTREAM
RIDGE REMAINS ACROSS THE PAC-NW POSSIBLY STRETCHING INTO THE
CANADIAN ROCKIES...WHICH COULD ALLOW FOR A CONTINUED NORTHWEST FLOW
ACROSS THE GREAT LAKES REGION FOR THE BULK OF THE EXTENDED. IN
ADDITION TO THIS GUIDANCE ALSO FAVORS A SLIGHTLY COOLER EXTENDED
FORECAST...HOWEVER DRY. GUIDANCE IS INDICATING WITH A HIGH LEVEL OF
CONFIDENCE THAT SFC RIDGING WILL INFLUENCE THE REGION FOR THE BULK
OF THE EXTENDED.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT
SATURDAY.
RATZER/IZZI
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE
FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE
TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST
WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT
OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE
BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON.
CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH
EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT
NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND
SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR
OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT
LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED
ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS.
OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE
POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI
AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON.
SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH
COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH
CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A
SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED
BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM
SYSTEM MOVES INTO THE LOWER OHIO VALLEY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING.
RATZER/IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT.
SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING
THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR
IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE
AFTERNOON AND NIGHT.
MONDAY...MVFR WITH A CHC OF SNOW SHOWERS.
TUESDAY...SLT CHC OF SNOW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
MTF
&&
.MARINE...
225 PM CDT
A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE
WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN
CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY
NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD
FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS
SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER
THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS
WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY
AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW
CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY
THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE
DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE
MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS
FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH
TUESDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WATCH...ILZ032-ILZ033-ILZ039...7 AM SUNDAY TO 7 AM
MONDAY.
IN...WINTER STORM WATCH...INZ010-INZ011-INZ019...7 AM SUNDAY TO 7 AM
MONDAY.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
336 PM CDT FRI MAR 22 2013
.DISCUSSION...
307 PM CDT
TONIGHT THROUGH SATURDAY...
ANTI-CYCLONIC FLOW WILL CONTINUE TO PROVIDE DRY WEATHER THROUGH
TONIGHT...HOWEVER WILL BEGIN TO LIFT NORTH SAT AHEAD OF A POTENT
WINTER WEATHER SYSTEM SET TO ARRIVE LATE SAT NIGHT. VISIBLE
IMAGERY THIS AFTERNOON CONTINUES TO DEPICT THE CHANNEL OF CIRRUS
AND MID-LVL CLOUDS SLIDING NORTHEAST FROM THE NORTHERN PLAINS
SOUTHEAST THROUGH CENTRAL TENNESSEE. ANOTHER CHANNEL OF CLOUDS WAS
SLOWLY DROPPING SOUTH ACROSS THE UPPER PENINSULA OF MI TO
NORTHEAST LOWER MI. SFC TEMPS HAVE WARMED THIS AFTERNOON ACROSS
NORTHERN IL INTO THE MID 30S ACROSS MANY AREAS...HOWEVER WITH THE
LIGHT FLOW AND WARMER SFC TEMPS INITIALLY ACROSS CHICAGO...A LAKE
BREEZE HAS FORMED AND SLOWLY PUSHING INLAND. THIS HAS RESULTED IN
SFC TEMPS ALONG THE IMMEDIATE SHORELINE COOLING. OVERNIGHT TONIGHT
SKIES SHOULD REMAIN RELATIVELY CLEAR...POSSIBLY JUST A THIN CIRRUS
DECK WILL SLIDE OVERHEAD. LCL HI-RES GUIDANCE HAS SUGGESTED AN
ARRIVAL OF A THIN STRATUS LAYER EARLY SAT MORNING ACROSS NORTHEAST
IL...WHICH COULD POSE SIGNIFICANT CHALLENGES WITH THE HIGH
FORECAST FOR SAT.
OVERNIGHT TEMPS WILL COOL INTO THE TEENS ACROSS THE REMAINING
SNOWPACK AREAS OF FAR NORTHERN/NORTHWEST IL...OTHERWISE TEMPS WILL
RADIATE INTO THE LOW/MID 20S. THE WARMEST AREAS MAY END UP BEING THE
AREAS ADJACENT TO LAKE MICHIGAN. WINDS WILL ALSO BE TURNING
NORTHEASTERLY OFF OF THE LAKE OVERNIGHT.
GUIDANCE CONTINUES TO FAVOR THE MID-LVL RIDGE AXIS PUSHING EAST OF
THE AREA SAT EVE...ALLOWING FOR ANOTHER DAY OF DRY WEATHER. ALTHOUGH
IT DOES APPEAR THAT WITH WINDS BECOMING NORTH/NORTHEAST...THE
CHANCES OF TEMPS WARMING FURTHER INTO THE UPR 30S TO LOW 40S LOOKS
MINIMAL. HAVE OPTED TO NUDGE TEMPS DOWN A COUPLE OF DEGREES INTO THE
MID/UPR 30S.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...
LATE SEASON WINTER STORM CONTINUES TO BE THE MAIN FOCUS FOR THE OHIO
VALLEY. AT THIS TIME THE ECMWF CONTINUES TO TAKE THE SYSTEM FURTHER
SOUTH...PULLING THE SNOW TOTALS FURTHER SOUTH INTO CENTRAL IL/IN FOR
THE ENTIRE EVENT. SREF PLUMES HAVE INDICATED THAT MANY LOCATIONS
ALONG AND SOUTH OF I-80 WILL SEE SEVERAL INCHES OF SNOWFALL FOR THE
EVENT...WITH A RANGE FROM 1 INCH TO POSSIBLE IN EXCESS OF 6 INCHES.
GUIDANCE CONTINUES TO SHOW CORRECTIONS ON THE PLACEMENT/INTENSITY OF
THIS SYSTEM...AS WELL AS THE FGEN LOCATION. THE 850MB LOW IS
CURRENTLY PROGGED TO SLIDE EAST FROM CENTRAL MO INTO SOUTHCENTRAL
IL/CENTRAL IN. THIS COULD PLACE THE BEST FGEN BAND ACROSS THE
SOUTHERN CWFA...MAINLY LIVINGSTON/FORD/IROQUOIS COUNTIES STRETCHING
EAST INTO NEWTON/JASPER/BENTON COUNTIES. WILL PROCEED TO POST A
WINTER STORM WATCH FOR THE THESE COUNTIES IN THE SOUTHERN CWFA.
ENSEMBLES HAVE CONTINUED TO SHOW SOME STRENGTHENING IN THE 850MB
EASTERLY U-WIND ANOMS SUN TO NEARLY 4 SIGMA...30-40KTS. ABUNDANT
MOISTURE WILL BE PICKED UP AHEAD OF THIS SYSTEM FROM THE WESTERN
GULF OF MEXICO...IN ADDITION THE ATMOSPHERE ACROSS CENTRAL IL/IN
DOES APPEAR TO BECOME UNSTABLE AT THE PEAK OF THE STORM. ADDING TO
THE POSSIBILITY OF THUNDER/LIGHTNING ACCOMPANYING THE SNOW. THIS
COULD EASILY ENHANCE THE SNOWFALL RATES IN THE 15-00Z SUN TIMEFRAME.
AT THIS TIME IT APPEARS THE BEST LOCATION FOR THIS WOULD OCCUR ALONG
THE FAR SOUTHERN SECTIONS OF FORD/IROQUOIS/LIVINGSTON COUNTIES SUN.
THE LARGEST CAVEAT IS THAT HIGH PRESSURE WILL BE LIFTING TO THE
NORTH OF THE REGION...WITH A TIGHTENING GRADIENT DEVELOPING ALONG
THE NORTHERN PERIPHERY OF THE SYSTEM. THIS SETUP WOULD MOST LIKELY
SHARPEN UP THE SNOW TOTALS FROM WHERE IT SNOWS TO SEVERAL
INCHES...GIVEN THE DRY NEAR SFC ENVIRONMENT. HOWEVER...COMPOUNDING
THIS IS THE FACT THAT THE POTENTIAL FOR LAKE EFFECT SNOW INCREASES
GIVEN HOW COLD THE ENVIRONMENT WILL BE. THERMAL DIFFERENTIALS FROM
THE LAKE SFC/850MB BECOMES FAVORABLE IN THE 12-15 DEG RANGE. SO HAVE
MAINTAINED THE FORMATION OF LAKE SNOW FOR FAR NORTHEAST IL SUN.
WITH THE THICKENING CLOUD COVER AND A COOL BREEZE FROM THE
NORTHEAST...TEMPS SUN MAY STRUGGLE TO WARM BEYOND THE LOW 30S.
CONFIDENCE IN TEMPERATURES...HIGH.
CONFIDENCE IN SNOWFALL...MEDIUM.
CONFIDENCE IN SNOW TIMING...MEDIUM.
MONDAY THROUGH THURSDAY...
500MB TROUGH AXIS CONTINUES TO PIVOT EAST TOWARDS THE EAST COAST
MON...WITH WEAK RIDGING BEGINNING TO FORM ACROSS THE PAC-NW. IT
APPEARS BEYOND MON THROUGH THE REMAINDER OF THE WEEKEND THE UPSTREAM
RIDGE REMAINS ACROSS THE PAC-NW POSSIBLY STRETCHING INTO THE
CANADIAN ROCKIES...WHICH COULD ALLOW FOR A CONTINUED NORTHWEST FLOW
ACROSS THE GREAT LAKES REGION FOR THE BULK OF THE EXTENDED. IN
ADDITION TO THIS GUIDANCE ALSO FAVORS A SLIGHTLY COOLER EXTENDED
FORECAST...HOWEVER DRY. GUIDANCE IS INDICATING WITH A HIGH LEVEL OF
CONFIDENCE THAT SFC RIDGING WILL INFLUENCE THE REGION FOR THE BULK
OF THE EXTENDED.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING
TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS.
* POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT
SATURDAY.
RATZER
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE
FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE
TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST
WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT
OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE
BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON.
CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH
EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT
NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND
SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR
OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT
LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED
ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS.
OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE
POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI
AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON.
SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH
COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH
CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A
SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED
BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM
SYSTEM MOVES INTO THE LOWER OHIO VALLEY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE ON LAKE BREEZE TIMING.
* LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT.
SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING
THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR
IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE
AFTERNOON AND NIGHT.
MONDAY...MVFR WITH A CHC OF SNOW SHOWERS.
TUESDAY...SLT CHC OF SNOW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
MTF
&&
.MARINE...
225 PM CDT
A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE
WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN
CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY
NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD
FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS
SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER
THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS
WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY
AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW
CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY
THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE
DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE
MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS
FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH
TUESDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WATCH...ILZ032-ILZ033-ILZ039...7 AM SUNDAY TO 7 AM
MONDAY.
IN...WINTER STORM WATCH...INZ010-INZ011-INZ019...7 AM SUNDAY TO 7 AM
MONDAY.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
309 PM CDT FRI MAR 22 2013
.DISCUSSION...
307 PM CDT
TONIGHT THROUGH SATURDAY...
ANTI-CYCLONIC FLOW WILL CONTINUE TO PROVIDE DRY WEATHER THROUGH
TONIGHT...HOWEVER WILL BEGIN TO LIFT NORTH SAT AHEAD OF A POTENT
WINTER WEATHER SYSTEM SET TO ARRIVE LATE SAT NIGHT. VISIBLE
IMAGERY THIS AFTERNOON CONTINUES TO DEPICT THE CHANNEL OF CIRRUS
AND MID-LVL CLOUDS SLIDING NORTHEAST FROM THE NORTHERN PLAINS
SOUTHEAST THROUGH CENTRAL TENNESSEE. ANOTHER CHANNEL OF CLOUDS WAS
SLOWLY DROPPING SOUTH ACROSS THE UPPER PENINSULA OF MI TO
NORTHEAST LOWER MI. SFC TEMPS HAVE WARMED THIS AFTERNOON ACROSS
NORTHERN IL INTO THE MID 30S ACROSS MANY AREAS...HOWEVER WITH THE
LIGHT FLOW AND WARMER SFC TEMPS INITIALLY ACROSS CHICAGO...A LAKE
BREEZE HAS FORMED AND SLOWLY PUSHING INLAND. THIS HAS RESULTED IN
SFC TEMPS ALONG THE IMMEDIATE SHORELINE COOLING. OVERNIGHT TONIGHT
SKIES SHOULD REMAIN RELATIVELY CLEAR...POSSIBLY JUST A THIN CIRRUS
DECK WILL SLIDE OVERHEAD. LCL HI-RES GUIDANCE HAS SUGGESTED AN
ARRIVAL OF A THIN STRATUS LAYER EARLY SAT MORNING ACROSS NORTHEAST
IL...WHICH COULD POSE SIGNIFICANT CHALLENGES WITH THE HIGH
FORECAST FOR SAT.
OVERNIGHT TEMPS WILL COOL INTO THE TEENS ACROSS THE REMAINING
SNOWPACK AREAS OF FAR NORTHERN/NORTHWEST IL...OTHERWISE TEMPS WILL
RADIATE INTO THE LOW/MID 20S. THE WARMEST AREAS MAY END UP BEING THE
AREAS ADJACENT TO LAKE MICHIGAN. WINDS WILL ALSO BE TURNING
NORTHEASTERLY OFF OF THE LAKE OVERNIGHT.
GUIDANCE CONTINUES TO FAVOR THE MID-LVL RIDGE AXIS PUSHING EAST OF
THE AREA SAT EVE...ALLOWING FOR ANOTHER DAY OF DRY WEATHER. ALTHOUGH
IT DOES APPEAR THAT WITH WINDS BECOMING NORTH/NORTHEAST...THE
CHANCES OF TEMPS WARMING FURTHER INTO THE UPR 30S TO LOW 40S LOOKS
MINIMAL. HAVE OPTED TO NUDGE TEMPS DOWN A COUPLE OF DEGREES INTO THE
MID/UPR 30S.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...
LATE SEASON WINTER STORM CONTINUES TO BE THE MAIN FOCUS FOR THE OHIO
VALLEY. AT THIS TIME THE ECMWF CONTINUES TO TAKE THE SYSTEM FURTHER
SOUTH...PULLING THE SNOW TOTALS FURTHER SOUTH INTO CENTRAL IL/IN FOR
THE ENTIRE EVENT. SREF PLUMES HAVE INDICATED THAT MANY LOCATIONS
ALONG AND SOUTH OF I-80 WILL SEE SEVERAL INCHES OF SNOWFALL FOR THE
EVENT...WITH A RANGE FROM 1 INCH TO POSSIBLE IN EXCESS OF 6 INCHES.
GUIDANCE CONTINUES TO SHOW CORRECTIONS ON THE PLACEMENT/INTENSITY OF
THIS SYSTEM...AS WELL AS THE FGEN LOCATION. THE 850MB LOW IS
CURRENTLY PROGGED TO SLIDE EAST FROM CENTRAL MO INTO SOUTHCENTRAL
IL/CENTRAL IN. THIS COULD PLACE THE BEST FGEN BAND ACROSS THE
SOUTHERN CWFA...MAINLY LIVINGSTON/FORD/IROQUOIS COUNTIES STRETCHING
EAST INTO NEWTON/JASPER/BENTON COUNTIES. WILL PROCEED TO POST A
WINTER STORM WATCH FOR THE THESE COUNTIES IN THE SOUTHERN CWFA.
ENSEMBLES HAVE CONTINUED TO SHOW SOME STRENGTHENING IN THE 850MB
EASTERLY U-WIND ANOMS SUN TO NEARLY 4 SIGMA...30-40KTS. ABUNDANT
MOISTURE WILL BE PICKED UP AHEAD OF THIS SYSTEM FROM THE WESTERN
GULF OF MEXICO...IN ADDITION THE ATMOSPHERE ACROSS CENTRAL IL/IN
DOES APPEAR TO BECOME UNSTABLE AT THE PEAK OF THE STORM. ADDING TO
THE POSSIBILITY OF THUNDER/LIGHTNING ACCOMPANYING THE SNOW. THIS
COULD EASILY ENHANCE THE SNOWFALL RATES IN THE 15-00Z SUN TIMEFRAME.
AT THIS TIME IT APPEARS THE BEST LOCATION FOR THIS WOULD OCCUR ALONG
THE FAR SOUTHERN SECTIONS OF FORD/IROQUOIS/LIVINGSTON COUNTIES SUN.
THE LARGEST CAVEAT IS THAT HIGH PRESSURE WILL BE LIFTING TO THE
NORTH OF THE REGION...WITH A TIGHTENING GRADIENT DEVELOPING ALONG
THE NORTHERN PERIPHERY OF THE SYSTEM. THIS SETUP WOULD MOST LIKELY
SHARPEN UP THE SNOW TOTALS FROM WHERE IT SNOWS TO SEVERAL
INCHES...GIVEN THE DRY NEAR SFC ENVIRONMENT. HOWEVER...COMPOUNDING
THIS IS THE FACT THAT THE POTENTIAL FOR LAKE EFFECT SNOW INCREASES
GIVEN HOW COLD THE ENVIRONMENT WILL BE. THERMAL DIFFERENTIALS FROM
THE LAKE SFC/850MB BECOMES FAVORABLE IN THE 12-15 DEG RANGE. SO HAVE
MAINTAINED THE FORMATION OF LAKE SNOW FOR FAR NORTHEAST IL SUN.
WITH THE THICKENING CLOUD COVER AND A COOL BREEZE FROM THE
NORTHEAST...TEMPS SUN MAY STRUGGLE TO WARM BEYOND THE LOW 30S.
CONFIDENCE IN TEMPERATURES...HIGH.
CONFIDENCE IN SNOWFALL...MEDIUM.
CONFIDENCE IN SNOW TIMING...MEDIUM.
MONDAY THROUGH THURSDAY...
500MB TROUGH AXIS CONTINUES TO PIVOT EAST TOWARDS THE EAST COAST
MON...WITH WEAK RIDGING BEGINNING TO FORM ACROSS THE PAC-NW. IT
APPEARS BEYOND MON THROUGH THE REMAINDER OF THE WEEKEND THE UPSTREAM
RIDGE REMAINS ACROSS THE PAC-NW POSSIBLY STRETCHING INTO THE
CANADIAN ROCKIES...WHICH COULD ALLOW FOR A CONTINUED NORTHWEST FLOW
ACROSS THE GREAT LAKES REGION FOR THE BULK OF THE EXTENDED. IN
ADDITION TO THIS GUIDANCE ALSO FAVORS A SLIGHTLY COOLER EXTENDED
FORECAST...HOWEVER DRY. GUIDANCE IS INDICATING WITH A HIGH LEVEL OF
CONFIDENCE THAT SFC RIDGING WILL INFLUENCE THE REGION FOR THE BULK
OF THE EXTENDED.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING
TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS.
* POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT
SATURDAY.
RATZER
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE
FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE
TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST
WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT
OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE
BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON.
CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH
EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT
NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND
SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR
OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT
LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED
ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS.
OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE
POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI
AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON.
SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH
COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH
CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A
SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED
BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM
SYSTEM MOVES INTO THE LOWER OHIO VALLEY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE ON LAKE BREEZE TIMING.
* LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT.
SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING
THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR
IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE
AFTERNOON AND NIGHT.
MONDAY...MVFR WITH A CHC OF SNOW SHOWERS.
TUESDAY...SLT CHC OF SNOW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
MTF
&&
.MARINE...
225 PM CDT
A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE
WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN
CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY
NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD
FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS
SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER
THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS
WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY
AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW
CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY
THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE
DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE
MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS
FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH
TUESDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
239 PM CDT FRI MAR 22 2013
.DISCUSSION...
524 AM CDT
POTENTIAL FOR SIGNIFICANT SNOWFALL SUNDAY AND SUNDAY
NIGHT...ESPECIALLY S OF I-80 AND NEAR THE IL AND IN LAKE SHORE.
ATTENTION FOCUSED ON POTENTIAL OF SPRING SNOW STORM TO AFFECT THE
LOCAL FORECAST AREA BEGINNING OVERNIGHT SATURDAY NIGHT ACROSS THE
SW HALF OF THE FA AND THEN ACROSS THE ENTIRE FA SUNDAY AND SUNDAY
NIGHT. ALSO POTENTIAL FOR LAKE ENHANCED SNOWFALL ALONG THE IL AND
IN SHORES DURING SUNDAY AND SUNDAY NIGHT AS STRONG COLD NE LOW
LEVEL FLOW BACKS TO OUT OF THE N WITH TIME AS THE SURFACE LOW OF
THE STORM SYSTEM PASSES S AND SE OF THE REGION...POTENTIALLY
CONTRIBUTING ENHANCED CONVECTIVE SNOWFALL TOO THE WIDESPREAD
SYSTEM SNOW.
THIS STORM HAS BEEN TOUGH TO NAIL DOWN AS MODELS HAVE BEEN
OFFERING VARIOUS SOLUTIONS TO THE PATH OF THE STORM ACROSS THE
CENTRAL U.S. OVER THE LAST SEVERAL RUNS. LATEST MODEL OUTPUT
SEEMS TO HAVE CONVERGED SIGNIFICANTLY OVER PAST 24 HOURS AND
CONTINUITY OF EACH MODEL FROM PREVIOUS MODEL RUN TO THE LATEST
RUN...WITH ONE EXCEPTION...LENDS CREDENCE AND MORE CONFIDENCE IN
A MORE SOUTHERLY TRACK OF THE UPPER LOW. A JET MAX CURRENTLY
DIVING SSE OVER NV AND NORTHERN CA IS TO TURN SE OVER THE DESERT
SW AND THE SOUTHERN ROCKIES TONIGHT AND SATURDAY MORNING THEN HEAD
E OVER THE SOUTHERN PLAINS SATURDAY AFTERNOON AND EVENING BEFORE
TURNING ENE OVERNIGHT CROSSING THE SOUTHERN MS VALLEY AND
REACHING THE TN VALLEY BY SUNDAY EVENING.
LOOP OF SATELLITE WATER VAPOR IMAGERY ALREADY REVEALS A
DEVELOPING UPPER LOW CIRCULATION OVER THE INTERIOR PACIFIC NW. IN
RESPONSE TO THE JET THIS LOW IS PROGGED TO STRENGHTEN AS IT CURVES
SE AND E OVER THE CENTRAL ROCKIES AND THE CENTRAL PLAINS DURING
SATURDAY AND THEN E OVER THE MID MS VALLEY. BESIDES THE OUTLIER
OPERATIONAL 00Z GFS...MODEL CONSENSUS INCLUDING GFS ENSEMBLE
MEMBERS...GFS ENSEMBLE MEAN...AND SREF MEAN IS FOR THE UPPER LOW
TO TRACK ACROSS SOUTHERN MO OR ALONG THE MO-AR BORDER TO THE
LOWER OH VALLEY DURING SUNDAY. WITH THIS SOUTHERN TRACK THE
ASSOCIATED 850HPA AND SURFACE LOWS ARE PROGGED TO MOVE E ACROSS
SOUTHERN MO SATURDAY NIGHT AND THEN TO THE FA LOWER OH VALLEY BY
18Z SUNDAY.
BEST FORCING FROM ISENTROPIC UPGLIDE AND FRONTOGENESIS IS PROGGED
TO STRETCH FROM NORTHERN MO ACROSS CENTRAL IL AND CENTRAL IN
DURING THE SATURDAY NIGHT TO SUNDAY NIGHT PERIOD. WHILE FEEL
FAIRLY CONFIDENT IN THE SOUTHERN TRACK OF THE SYSTEM A BIT MORE
NORTHERLY TRACK...WHILE A VERY MINOR SHIFT FOR A HEMISPHERIC
MODEL...WOULD BRING THE THREAT OF A HEAVY SPRING SNOWFALL TO THE
SOUTHERN HALF OF THE LOCAL FORECAST AREA. BASED ON LATEST GUIDANCE
HAVE A RANCE OF SNOWFALL FROM 1 INCH ALONG THE WI BORDER TO 6 TO 7
INCHES ACROSS FAR SOUTHERN LASALLE...SOUTHERN FORD...SOUTHERN
IROQUOIS AND BENTON COUNTIES WITH THE 3 INCH TOTAL GENERALLY ALONG
THE I-80 CORRIDOR.
A WILD CARD THROWN INTO THE MIX IS THE POTENTIAL FOR LAKE
EFFECT/ENHANCED SNOW TO OCCUR. DURING SUNDAY AND SUNDAY NIGHT THE
COLD AIR IN PLACE ACROSS CANADA...THE GREAT LAKES AND THE NE U.S.
WILL TRAVEL ACROSS LAKE MI ON NE TO NNE FLOW. FORECAST TEMPERATURE
PROFILES INDICATE A CLOUD DEPTH OVER THE LAKE OF 5 TO 7K FT WITH
TOPS 7-9K FT. EXPECT ENHANCED SNOWFALL NEAR THE IL AND IN SHORES
ESPECIALLY SUN AFTERNOON AND EVENING AS THE BACKING OF THE FLOW
DRAMATICALLY INCREASES THE FETCH OVER THE LAKE. THE LAKE EFFECT
COULD LOCALLY DOUBLE SNOW AMOUNTS ALONG THE IL SHORE AND TRIPP LE
THEM IN NW IN.
ONCE ANY LINGER SNOW OR LAKE EFFECT SNOW SHOWERS END MONDAY AFTER
AN UPPER TROUGH TRAILING W AND NW FROM THE UPPER LOW PROGGED TO BE
WEAKENING AS IT MOVES FROM THE UPPER OH VALLEY ACROSS THE
NORTHEASTERN U.S. THE REST OF THE WEAK LOOKS TO BE TRANQUIL
OUTSIDE OF A SLIGHT CHANCE OF LIGHT SNOW TUESDAY AS ANOTHER UPPER
TROUGH DROPS S FROM THE SOUTHERN GREAT LAKES.
WHILE THE AMPLITUDE OF THE UPPER PATTERN ACROSS THE CONUS
DECREASES WITH TIME DURING MID AND LATE WEEK TEMPERATURES ARE
EXPECTED TO MODERATE SLIGHTLY AND REMAIN WELL BELOW NORMAL FOR
LATE MARCH AS AN UPPER TROUGH REMAINS OVER EASTERN NOAM AND THE
WESTERLIES STAY WELL SOUTH.
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING
TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS.
* POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT
SATURDAY.
RATZER
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE
FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE
TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST
WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT
OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE
BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON.
CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH
EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT
NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND
SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR
OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT
LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED
ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS.
OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE
POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI
AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON.
SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH
COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH
CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A
SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED
BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM
SYSTEM MOVES INTO THE LOWER OHIO VALLEY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE ON LAKE BREEZE TIMING.
* LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT.
SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING
THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR
IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE
AFTERNOON AND NIGHT.
MONDAY...MVFR WITH A CHC OF SNOW SHOWERS.
TUESDAY...SLT CHC OF SNOW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
MTF
&&
.MARINE...
225 PM CDT
A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE
WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN
CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY
NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD
FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS
SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER
THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS
WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY
AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW
CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY
THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE
DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE
MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS
FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH
TUESDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
225 PM CDT FRI MAR 22 2013
.DISCUSSION...
524 AM CDT
POTENTIAL FOR SIGNIFICANT SNOWFALL SUNDAY AND SUNDAY
NIGHT...ESPECIALLY S OF I-80 AND NEAR THE IL AND IN LAKE SHORE.
ATTENTION FOCUSED ON POTENTIAL OF SPRING SNOW STORM TO AFFECT THE
LOCAL FORECAST AREA BEGINNING OVERNIGHT SATURDAY NIGHT ACROSS THE
SW HALF OF THE FA AND THEN ACROSS THE ENTIRE FA SUNDAY AND SUNDAY
NIGHT. ALSO POTENTIAL FOR LAKE ENHANCED SNOWFALL ALONG THE IL AND
IN SHORES DURING SUNDAY AND SUNDAY NIGHT AS STRONG COLD NE LOW
LEVEL FLOW BACKS TO OUT OF THE N WITH TIME AS THE SURFACE LOW OF
THE STORM SYSTEM PASSES S AND SE OF THE REGION...POTENTIALLY
CONTRIBUTING ENHANCED CONVECTIVE SNOWFALL TOO THE WIDESPREAD
SYSTEM SNOW.
THIS STORM HAS BEEN TOUGH TO NAIL DOWN AS MODELS HAVE BEEN
OFFERING VARIOUS SOLUTIONS TO THE PATH OF THE STORM ACROSS THE
CENTRAL U.S. OVER THE LAST SEVERAL RUNS. LATEST MODEL OUTPUT
SEEMS TO HAVE CONVERGED SIGNIFICANTLY OVER PAST 24 HOURS AND
CONTINUITY OF EACH MODEL FROM PREVIOUS MODEL RUN TO THE LATEST
RUN...WITH ONE EXCEPTION...LENDS CREDENCE AND MORE CONFIDENCE IN
A MORE SOUTHERLY TRACK OF THE UPPER LOW. A JET MAX CURRENTLY
DIVING SSE OVER NV AND NORTHERN CA IS TO TURN SE OVER THE DESERT
SW AND THE SOUTHERN ROCKIES TONIGHT AND SATURDAY MORNING THEN HEAD
E OVER THE SOUTHERN PLAINS SATURDAY AFTERNOON AND EVENING BEFORE
TURNING ENE OVERNIGHT CROSSING THE SOUTHERN MS VALLEY AND
REACHING THE TN VALLEY BY SUNDAY EVENING.
LOOP OF SATELLITE WATER VAPOR IMAGERY ALREADY REVEALS A
DEVELOPING UPPER LOW CIRCULATION OVER THE INTERIOR PACIFIC NW. IN
RESPONSE TO THE JET THIS LOW IS PROGGED TO STRENGHTEN AS IT CURVES
SE AND E OVER THE CENTRAL ROCKIES AND THE CENTRAL PLAINS DURING
SATURDAY AND THEN E OVER THE MID MS VALLEY. BESIDES THE OUTLIER
OPERATIONAL 00Z GFS...MODEL CONSENSUS INCLUDING GFS ENSEMBLE
MEMBERS...GFS ENSEMBLE MEAN...AND SREF MEAN IS FOR THE UPPER LOW
TO TRACK ACROSS SOUTHERN MO OR ALONG THE MO-AR BORDER TO THE
LOWER OH VALLEY DURING SUNDAY. WITH THIS SOUTHERN TRACK THE
ASSOCIATED 850HPA AND SURFACE LOWS ARE PROGGED TO MOVE E ACROSS
SOUTHERN MO SATURDAY NIGHT AND THEN TO THE FA LOWER OH VALLEY BY
18Z SUNDAY.
BEST FORCING FROM ISENTROPIC UPGLIDE AND FRONTOGENESIS IS PROGGED
TO STRETCH FROM NORTHERN MO ACROSS CENTRAL IL AND CENTRAL IN
DURING THE SATURDAY NIGHT TO SUNDAY NIGHT PERIOD. WHILE FEEL
FAIRLY CONFIDENT IN THE SOUTHERN TRACK OF THE SYSTEM A BIT MORE
NORTHERLY TRACK...WHILE A VERY MINOR SHIFT FOR A HEMISPHERIC
MODEL...WOULD BRING THE THREAT OF A HEAVY SPRING SNOWFALL TO THE
SOUTHERN HALF OF THE LOCAL FORECAST AREA. BASED ON LATEST GUIDANCE
HAVE A RANCE OF SNOWFALL FROM 1 INCH ALONG THE WI BORDER TO 6 TO 7
INCHES ACROSS FAR SOUTHERN LASALLE...SOUTHERN FORD...SOUTHERN
IROQUOIS AND BENTON COUNTIES WITH THE 3 INCH TOTAL GENERALLY ALONG
THE I-80 CORRIDOR.
A WILD CARD THROWN INTO THE MIX IS THE POTENTIAL FOR LAKE
EFFECT/ENHANCED SNOW TO OCCUR. DURING SUNDAY AND SUNDAY NIGHT THE
COLD AIR IN PLACE ACROSS CANADA...THE GREAT LAKES AND THE NE U.S.
WILL TRAVEL ACROSS LAKE MI ON NE TO NNE FLOW. FORECAST TEMPERATURE
PROFILES INDICATE A CLOUD DEPTH OVER THE LAKE OF 5 TO 7K FT WITH
TOPS 7-9K FT. EXPECT ENHANCED SNOWFALL NEAR THE IL AND IN SHORES
ESPECIALLY SUN AFTERNOON AND EVENING AS THE BACKING OF THE FLOW
DRAMATICALLY INCREASES THE FETCH OVER THE LAKE. THE LAKE EFFECT
COULD LOCALLY DOUBLE SNOW AMOUNTS ALONG THE IL SHORE AND TRIPP LE
THEM IN NW IN.
ONCE ANY LINGER SNOW OR LAKE EFFECT SNOW SHOWERS END MONDAY AFTER
AN UPPER TROUGH TRAILING W AND NW FROM THE UPPER LOW PROGGED TO BE
WEAKENING AS IT MOVES FROM THE UPPER OH VALLEY ACROSS THE
NORTHEASTERN U.S. THE REST OF THE WEAK LOOKS TO BE TRANQUIL
OUTSIDE OF A SLIGHT CHANCE OF LIGHT SNOW TUESDAY AS ANOTHER UPPER
TROUGH DROPS S FROM THE SOUTHERN GREAT LAKES.
WHILE THE AMPLITUDE OF THE UPPER PATTERN ACROSS THE CONUS
DECREASES WITH TIME DURING MID AND LATE WEEK TEMPERATURES ARE
EXPECTED TO MODERATE SLIGHTLY AND REMAIN WELL BELOW NORMAL FOR
LATE MARCH AS AN UPPER TROUGH REMAINS OVER EASTERN NOAM AND THE
WESTERLIES STAY WELL SOUTH.
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING
TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS.
* POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT
SATURDAY.
RATZER
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE
FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE
TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST
WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT
OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE
BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON.
CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH
EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT
NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND
SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR
OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT
LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED
ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS.
OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE
POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI
AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON.
SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH
COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH
CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A
SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED
BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM
SYSTEM MOVES INTO THE LOWER OHIO VALLEY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM-LOW CONFIDENCE ON LAKE BREEZE TIMING.
* LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT.
SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING
THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR
IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE
AFTERNOON AND NIGHT.
MONDAY...MVFR WITH A CHC OF SNOW SHOWERS.
TUESDAY...SLT CHC OF SNOW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
MTF
&&
.MARINE...
225 PM CDT
A SURFACE RIDGE OF HIGH PRESSURE IS CURRENTLY DOMINATING ACROSS THE
WESTERN LAKES. THIS IS PRODUCING FAIRLY WEAK SURFACE FLOW. THE MAIN
CONCERNS DURING THE PERIOD WILL BE LATER THIS WEEKEND AND INTO EARLY
NEXT WEEK. A POTENT STORM SYSTEM IS EXPECTED TO LIFT NORTHEASTWARD
FROM THE LOWER MISSISSIPPI VALLEY ACROSS OHIO VALLEY...AND THIS
SHOULD RESULT IN A PERIOD OF STRONGER NORTH-NORTHEASTERLY WINDS OVER
THE LAKE SUNDAY INTO MONDAY. IT CURRENTLY APPEARS THAT THE WINDS
WILL REALLY RAMP UP TO AROUND 30 KT OUT OF THE NORTHEAST ON SUNDAY
AS THE SURFACE LOW TRACKS ACROSS WESTERN KENTUCKY. AS THE LOW
CONTINUES EASTWARD ACROSS THE OHIO VALLEY SUNDAY NIGHT INTO MONDAY
THE WINDS WILL BECOME NORTHERLY. A PERIOD OF GALES IS POSSIBLE
DURING THIS PERIOD...ESPECIALLY ACROSS THE SOUTHERN END OF LAKE
MICHIGAN. THIS SYSTEM WILL LIKELY RESULT IN SMALL CRAFT CONDITIONS
FOR BOTH THE ILLINOIS AND INDIANA SHORES FROM EARLY SUNDAY THROUGH
TUESDAY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1251 PM CDT FRI MAR 22 2013
.DISCUSSION...
524 AM CDT
POTENTIAL FOR SIGNIFICANT SNOWFALL SUNDAY AND SUNDAY
NIGHT...ESPECIALLY S OF I-80 AND NEAR THE IL AND IN LAKE SHORE.
ATTENTION FOCUSED ON POTENTIAL OF SPRING SNOW STORM TO AFFECT THE
LOCAL FORECAST AREA BEGINNING OVERNIGHT SATURDAY NIGHT ACROSS THE
SW HALF OF THE FA AND THEN ACROSS THE ENTIRE FA SUNDAY AND SUNDAY
NIGHT. ALSO POTENTIAL FOR LAKE ENHANCED SNOWFALL ALONG THE IL AND
IN SHORES DURING SUNDAY AND SUNDAY NIGHT AS STRONG COLD NE LOW
LEVEL FLOW BACKS TO OUT OF THE N WITH TIME AS THE SURFACE LOW OF
THE STORM SYSTEM PASSES S AND SE OF THE REGION...POTENTIALLY
CONTRIBUTING ENHANCED CONVECTIVE SNOWFALL TOO THE WIDESPREAD
SYSTEM SNOW.
THIS STORM HAS BEEN TOUGH TO NAIL DOWN AS MODELS HAVE BEEN
OFFERING VARIOUS SOLUTIONS TO THE PATH OF THE STORM ACROSS THE
CENTRAL U.S. OVER THE LAST SEVERAL RUNS. LATEST MODEL OUTPUT
SEEMS TO HAVE CONVERGED SIGNIFICANTLY OVER PAST 24 HOURS AND
CONTINUITY OF EACH MODEL FROM PREVIOUS MODEL RUN TO THE LATEST
RUN...WITH ONE EXCEPTION...LENDS CREDENCE AND MORE CONFIDENCE IN
A MORE SOUTHERLY TRACK OF THE UPPER LOW. A JET MAX CURRENTLY
DIVING SSE OVER NV AND NORTHERN CA IS TO TURN SE OVER THE DESERT
SW AND THE SOUTHERN ROCKIES TONIGHT AND SATURDAY MORNING THEN HEAD
E OVER THE SOUTHERN PLAINS SATURDAY AFTERNOON AND EVENING BEFORE
TURNING ENE OVERNIGHT CROSSING THE SOUTHERN MS VALLEY AND
REACHING THE TN VALLEY BY SUNDAY EVENING.
LOOP OF SATELLITE WATER VAPOR IMAGERY ALREADY REVEALS A
DEVELOPING UPPER LOW CIRCULATION OVER THE INTERIOR PACIFIC NW. IN
RESPONSE TO THE JET THIS LOW IS PROGGED TO STRENGHTEN AS IT CURVES
SE AND E OVER THE CENTRAL ROCKIES AND THE CENTRAL PLAINS DURING
SATURDAY AND THEN E OVER THE MID MS VALLEY. BESIDES THE OUTLIER
OPERATIONAL 00Z GFS...MODEL CONSENSUS INCLUDING GFS ENSEMBLE
MEMBERS...GFS ENSEMBLE MEAN...AND SREF MEAN IS FOR THE UPPER LOW
TO TRACK ACROSS SOUTHERN MO OR ALONG THE MO-AR BORDER TO THE
LOWER OH VALLEY DURING SUNDAY. WITH THIS SOUTHERN TRACK THE
ASSOCIATED 850HPA AND SURFACE LOWS ARE PROGGED TO MOVE E ACROSS
SOUTHERN MO SATURDAY NIGHT AND THEN TO THE FA LOWER OH VALLEY BY
18Z SUNDAY.
BEST FORCING FROM ISENTROPIC UPGLIDE AND FRONTOGENESIS IS PROGGED
TO STRETCH FROM NORTHERN MO ACROSS CENTRAL IL AND CENTRAL IN
DURING THE SATURDAY NIGHT TO SUNDAY NIGHT PERIOD. WHILE FEEL
FAIRLY CONFIDENT IN THE SOUTHERN TRACK OF THE SYSTEM A BIT MORE
NORTHERLY TRACK...WHILE A VERY MINOR SHIFT FOR A HEMISPHERIC
MODEL...WOULD BRING THE THREAT OF A HEAVY SPRING SNOWFALL TO THE
SOUTHERN HALF OF THE LOCAL FORECAST AREA. BASED ON LATEST GUIDANCE
HAVE A RANCE OF SNOWFALL FROM 1 INCH ALONG THE WI BORDER TO 6 TO 7
INCHES ACROSS FAR SOUTHERN LASALLE...SOUTHERN FORD...SOUTHERN
IROQUOIS AND BENTON COUNTIES WITH THE 3 INCH TOTAL GENERALLY ALONG
THE I-80 CORRIDOR.
A WILD CARD THROWN INTO THE MIX IS THE POTENTIAL FOR LAKE
EFFECT/ENHANCED SNOW TO OCCUR. DURING SUNDAY AND SUNDAY NIGHT THE
COLD AIR IN PLACE ACROSS CANADA...THE GREAT LAKES AND THE NE U.S.
WILL TRAVEL ACROSS LAKE MI ON NE TO NNE FLOW. FORECAST TEMPERATURE
PROFILES INDICATE A CLOUD DEPTH OVER THE LAKE OF 5 TO 7K FT WITH
TOPS 7-9K FT. EXPECT ENHANCED SNOWFALL NEAR THE IL AND IN SHORES
ESPECIALLY SUN AFTERNOON AND EVENING AS THE BACKING OF THE FLOW
DRAMATICALLY INCREASES THE FETCH OVER THE LAKE. THE LAKE EFFECT
COULD LOCALLY DOUBLE SNOW AMOUNTS ALONG THE IL SHORE AND TRIPP LE
THEM IN NW IN.
ONCE ANY LINGER SNOW OR LAKE EFFECT SNOW SHOWERS END MONDAY AFTER
AN UPPER TROUGH TRAILING W AND NW FROM THE UPPER LOW PROGGED TO BE
WEAKENING AS IT MOVES FROM THE UPPER OH VALLEY ACROSS THE
NORTHEASTERN U.S. THE REST OF THE WEAK LOOKS TO BE TRANQUIL
OUTSIDE OF A SLIGHT CHANCE OF LIGHT SNOW TUESDAY AS ANOTHER UPPER
TROUGH DROPS S FROM THE SOUTHERN GREAT LAKES.
WHILE THE AMPLITUDE OF THE UPPER PATTERN ACROSS THE CONUS
DECREASES WITH TIME DURING MID AND LATE WEEK TEMPERATURES ARE
EXPECTED TO MODERATE SLIGHTLY AND REMAIN WELL BELOW NORMAL FOR
LATE MARCH AS AN UPPER TROUGH REMAINS OVER EASTERN NOAM AND THE
WESTERLIES STAY WELL SOUTH.
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* WEAK LAKE BREEZE DEVELOPING LATE AFTERNOON WITH WINDS SHIFTING
TO THE NORTHEAST OR EAST-NORTHEAST...10 KTS OR LESS.
* POTENTIAL FOR A LAKE-INDUCED MVFR STRATOCU CIG AROUND 2500 FT
SATURDAY.
RATZER
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE EXTENDS NORTHWEST TO SOUTHEAST ACROSS THE
FORECAST AREA THIS MIDDAY...WITH THE RIDGE AXIS JUST WEST OF THE
TERMINALS PER 17Z ANALYSIS. RESULTING LIGHT VARIABLE/NORTHWEST
WINDS LESS THAN 10 KT AND FULL SUNSHINE WAS ALLOWING DEVELOPMENT
OF ONSHORE WINDS ALONG THE LAKE MICHIGAN SHORE...WITH LIGHT LAKE
BREEZE EXPECTED TO PUSH SLOWLY INLAND THROUGH THE AFTERNOON.
CONFIDENCE IS SOMEWHAT LOW ON WHEN IT WILL REACH ORD/MDW...THOUGH
EVOLUTION OF SYNOPTIC FLOW WILL ALSO TEND TO SUPPORT A LIGHT
NORTHEAST BY EARLY EVENING. HIGH-RES RAP GUIDANCE SUGGESTS WIND
SHIFT THROUGH MDW/ORD BETWEEN 21-23Z WITH MDW/GYY LIKELY AN HOUR
OR SO SOONER THAN ORD...THOUGH WINDS SHOULD REMAIN FAIRLY LIGHT AT
LESS 10 KT. LIGHT NORTHEAST WINDS SHOULD THEN PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD...WITH A GRADUAL INCREASE IN SPEED
ESPECIALLY SATURDAY AFTERNOON AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS.
OTHERWISE...THE ONLY REAL CONCERN DURING THE PERIOD IS THE
POTENTIAL FOR SOME LAKE-INDUCED STRATOCU TO DEVELOP OVER THE CHI
AREA TERMINALS FOR A TIME SATURDAY MORNING/EARLY AFTERNOON.
SEVERAL MODELS HINTING AT CLOUD LAYER AROUND 2500 FT AGL WHICH
COULD PERHAPS FORM A FEW HOURS OF MVFR CEILING...THOUGH
CONFIDENCE IN DETAILS LOW ENOUGH TO MAINTAIN JUST A MENTION OF A
SCATTERED DECK AT THIS TIME. DETERIORATING CONDITIONS EXPECTED
BEYOND THIS TAF PERIOD LATER SATURDAY NIGHT...AS WINTER STORM
SYSTEM MOVES INTO THE LOWER OHIO VALLEY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM-LOW CONFIDENCE ON LAKE BREEZE TIMING.
* LOW CONFIDENCE IN MVFR CIG DEVELOPING SATURDAY MORNING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR. NE WIND GREATER THAN 10 KT.
SUNDAY...AN INCREASING CHC OF SNOW DURING THE DAY PEAKING DURING
THE 6 PM-MIDNIGHT TIME. MVFR LIKELY WITH A CHANCE FOR
IFR. ACCUMULATING SNOW POSSIBLE...NAMELY DURING THE
AFTERNOON AND NIGHT.
MONDAY...MVFR WITH A CHC OF SNOW SHOWERS.
TUESDAY...SLT CHC OF SNOW SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.
MTF
&&
.MARINE...
159 AM CDT
PERSISTENT LOW PRESSURE OVER SOUTHERN QUEBEC WILL BEGIN TO FINALLY
MOVE EAST LATER TODAY INTO TONIGHT EASING WIND SPEEDS ACROSS THE
NORTHERN PART OF THE LAKE. THIS SYSTEM DEPARTURE WILL ALLOW FOR THE
HIGH PRESSURE OVER THE MISSISSIPPI RIVER VALLEY TO SHIFT EAST OVER
LAKE MI INTO THE DAY SATURDAY. THE MOST PRONOUNCED SYSTEM IMPACTS
FOR THE LAKE WILL COME LATER SUNDAY...SUNDAY NIGHT...INTO THE DAY
MONDAY AS LOW PRESSURE MOVES FROM THE OZARKS REGION UP THE OHIO
RIVER VALLEY. SUCH A PATH WILL TIGHTEN THE PRESSURE GRADIENT ACROSS
LAKE MI...ESPECIALLY THE SOUTH. WINDS TO 30 KT LOOK VERY LIKELY OVER
THE SOUTHERN HALF INCLUDING NEARSHORE AREAS ON THE SOUTH...WITH GALE
FORCE WINDS POSSIBLE DEPENDING ON SYSTEM STRENGTH AND PRECISE PATH.
CIPS ANALOG GUIDANCE FOR SIMILAR REGIME MATCHES INDICATE A 50
PERCENT CHANCE OF WIND GUSTS EXCEEDING 30 KT ON NEARBY LAND AREAS
FOR THIS TIME...SO OVER WATER THE LIKELIHOOD IS HIGHER. SO BEYOND
THIS SYSTEM...GRADUALLY DIMINISHING NORTHERLY FLOW WILL CONTINUE FOR
A WHILE WITH PERSISTENT RIDGING BUILDING ONCE AGAIN OVER THE
MISSISSIPPI RIVER VALLEY.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS DES MOINES IA
702 PM CDT SAT MAR 23 2013
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TONIGHT/...
SYSTEM CONTINUES TO DIG SOUTHWARD THROUGH THE FRONT RANGE THIS
AFTERNOON WITH WIDESPREAD SNOWFALL ACROSS THE PLAINS. RECENTLY...
PRECIPITATION HAS BEEN EXPANDING FROM EASTERN KANSAS INTO WESTERN
MISSOURI IN WARM ADVECTION AIR OF THE SYSTEM. SOME MID TO HIGH
CLOUDINESS HAS SPREAD ACRS IOWA ALTHOUGH LOW LEVEL DRY AIR CONTINUES
TO MOVE IN FROM THE NORTHEAST. RECENT MODEL OUTPUT FROM THE 12Z GFS
PLUS THE HOURLY UPDATES FROM THE RAP CONTINUE TO INDICATE LATER
ONSET FOR MUCH OF THE FORECAST AREAS TONIGHT. THE NAM HAS BEEN MOST
AGGRESSIVE IN SPREADING SNOW INTO THE STATE THIS EVENING BUT SEEMS
TO BE THE ODD MODEL OUT AT THIS POINT WITH 18Z RUN BACKING OFF THE
MORE PROGRESSIVE 12Z RUN. HAVE GENERALLY STALLED THE ONSET OF
PRECIPITATION ACRS CENTRAL IOWA UNTIL LATER EVENING AND ACROSS THE
NORTH UNTIL WELL AFTER MIDNIGHT. NEWEST 18Z RAP WOULD NOT EVEN
BRING SNOW INTO DES MOINES UNTIL NEARLY 12Z ON SUNDAY AND REMAINS
DRY NORTH OF HIGHWAY 30.
ALL MODELS ALSO HAVE A BAND OF SNOW ACROSS NORTHWEST IOWA TONIGHT IN
A BAND OF WEAKER FORCING AHEAD OF UPPER CUTOFF CURRENTLY IN THE
DAKOTAS. ALREADY SOME LIGHT SNOW REPORTED IN SIOUX CITY AND HAVE
MAINTAINED THE POPS IN THE FAR WEST AND NORTHWEST FOR THIS AXIS OF
PRECIPITATION OVERNIGHT. ADVISORY WILL REMAIN INTACT FOR CURRENTLY
LOCATIONS ALTHOUGH HEAVIEST SNOWFALL APPEARS TO BE PRIMARILY IN THE
FAR SOUTHEAST OVERNIGHT WHERE AROUND 2 TO POSSIBLY 3 INCHES IS
EXPECTED. DES MOINES METRO MAY SEE AN INCH OR SO WITH LIGHT AMOUNTS
TOWARD THE NORTH.
.LONG TERM /SUNDAY THROUGH SATURDAY/...
MAIN FORECAST CONCERN WILL BE WITH PRECIPITATION CHANCES FOR
SUNDAY AND MONDAY. EXPECT WIDESPREAD SNOW TO BE ONGOING AT
BEGINNING OF PERIOD...ESPECIALLY ACROSS THE SOUTH AS LOW PRESSURE
SYSTEM PUSHES EAST ACROSS MISSOURI. SOUNDINGS AND CROSS SECTIONS
INDICATE GOOD SATURATION AND FORCING...ESPECIALLY ACROSS THE
SOUTH. FORCING BECOMES MUCH WEAKER FURTHER NORTH AWAY FROM THE
LOW...BUT ENOUGH TO RESULT IN AT LEAST LIGHT SNOWFALL THROUGHOUT
THE DAY MONDAY. BEST FORCING WILL BE EARLY...BEFORE 18Z AND EXPECT
TO SEE BEST SNOWFALL RATES THEN. BEST FORCING IS ABOVE THE
DENDRITIC LAYER...AND DO NOT ANTICIPATE SNOWFALL RATIOS TO BE MUCH
HIGHER THAN 10/1. DRY AIR WILL BEGIN TO PUSH BACK IN BEHIND SYSTEM
OVERNIGHT MONDAY...WITH PRECIPITATION ENDING ACROSS THE NE.
HOWEVER...GOOD VORT MAX PUSHING AROUND LOW WILL KEEP LINGERING
SNOW CHANCES ACROSS THE SW...BUT AGAIN WITH WEAKER FORCING ONLY
LIGHT SNOW EXPECTED. LINGERING LOW LEVEL SATURATION WILL ALLOW FOR
LINGERING LIGHT SNOW AND FLURRIES THROUGH MONDAY WITH COLD SURFACE
TEMPERATURES. SYSTEM WILL CONTINUE TO PULL EAST...AND MAY SEE
ADDITIONAL LINGERING FLURRIES THROUGH TUESDAY. TOTAL ACCUMULATIONS
ARE SIMILAR TO GOING WITH HIGHER TOTALS ACROSS THE SOUTH. WINDS WILL
BE STRONG BEHIND LOW...BUT WILL GENERALLY STAY BELOW 30MPH AND
WILL LEAD TO SOME IMPACTS...MOSTLY WITH ROADS AND REDUCED
VISIBILITIES....BUT DO NOT ANTICIPATE SIGNIFICANT IMPACTS WITH
SNOWFALL. GIVEN DURATION OF SNOWFALL...ADVISORY SEEMS WARRANTED
AND WILL LEAVE AS IS. HOWEVER...MAY NEED TO BE EXTENDED IN TIME
ACROSS THE SOUTH FOR LINGER SNOWFALL INTO MONDAY NIGHT...BUT WILL
LEAVE FOR FUTURE UPDATES AS MODELS CONTINUE TO VARY ON PLACEMENT
OF LOW.
TEMPERATURES WILL BEGIN TO WARM BY MID WEEK WITH SOUTHERLY SURFACE
FLOW AND INCREASING WAA. MODELS BRING ANOTHER LOW PRESSURE SYSTEM
ACROSS CANADA...WITH TRAILING FRONTAL BOUNDARY ACROSS MIDWEST.
THIS WILL BE FOCUS FOR PRECIPITATION CHANCES THROUGH THE WEEKEND.
HOWEVER...WITH WARMER TEMPERATURES PRECIPITATION LIKELY RAIN.
STILL SOME UNCERTAINTY IN TIMING AND LOCATION OF RAIN...AND HAVE
LEFT SLIGHT CHANCES FOR NOW.
&&
.AVIATION...24/00Z
RAPIDLY DETERIORATING CONDITIONS WILL SPREAD FROM SOUTHWEST TO
NORTHEAST TONIGHT AS A LARGE AREA OF LIGHT TO MODERATE SNOW
OVERSPREADS THE AREA. VFR CONDITIONS AHEAD OF THE SNOW WILL RAPIDLY
DROP TO IFR OR LOWER AT TIMES...WITH THE LIFR AND LOWER BEING
INTERMITTENT BUT IFR OR LOWER CONSISTENTLY PREVAILING AT MOST
LOCATIONS ONCE IT BEGINS. HAVE TRENDED THIS WAY IN THE 00Z
TAFS...WITH MOST OF THE DIFFICULTY BEING TIMING OF THE DETERIORATION
THIS EVENING. THIS WILL REQUIRE SOME AMENDMENTS...BUT ONCE THE AREA
SOCKS IN IT WILL STAY THAT WAY UNTIL AT LEAST 12Z SUNDAY.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM CDT
SUNDAY FOR ADAIR-ADAMS-APPANOOSE-CASS-CLARKE-DAVIS-DECATUR-LUCAS-
MADISON-MAHASKA-MARION-MONROE-RINGGOLD-TAYLOR-UNION-WAPELLO-
WARREN-WAYNE.
&&
$$
SHORT TERM...COGIL
LONG TERM...AWB
AVIATION...LEE
AREA FORECAST DISCUSSION
NWS TOPEKA KS
347 PM CDT FRI MAR 22 2013
.DISCUSSION...
20Z WATER VAPOR IMAGERY SHOWS A ELONGATED TROUGH FROM WESTERN
CANADA INTO THE NORTHERN ROCKIES WITH ENERGY DIGGING INTO ITS
BASE. AT THE SURFACE WEAK RIDGING REMAINS OVER THE NORTHERN AND
CENTRAL PLAINS WITH A COOL EASTERLY WIND.
FOR TONIGHT...LARGE SCALE FORCING FOR PRECIP LOOKS TO REMAIN TO THE
WEST ACROSS THE ROCKIES...SO THINK CHANCES FOR MEASURABLE PRECIP ARE
FAIRLY LOW. THE NAM AND RAP ARE SHOWING SOME WEAK ISENTROPIC ACCENT
DEVELOPING ON THE 280K SURFACE...SUGGESTING THERE COULD AGAIN BE
SOME PATCHY FREEZING DRIZZLE AFTER MIDNIGHT. BECAUSE OF THIS HAVE
INSERTED A SLIGHT CHANCE FOR FREEZING DRIZZLE. THINK THAT LOWS
TONIGHT SHOULD BE PRETTY SIMILAR TO THE LAST COUPLE NIGHTS GIVEN
OVERCAST SKIES AND LITTLE CHANGE TO THE AIRMASS.
FOR SATURDAY THROUGH SUNDAY...THE MAIN QUESTION IS WHETHER TO
UPGRADE TO A WARNING OR MAINTAIN THE WATCH. MODELS HAVE BEEN
CONSISTENT IN AMPLIFYING A SHORTWAVE AND MOVING IT ACROSS THE
FORECAST AREA. WITH VERY GOOD LARGE SCALE FORCING FROM THE PV
ANOMALY AND Q VECTOR CONVERGENCE...PRECIP IS EXPECTED TO BECOME
WIDESPREAD ACROSS WESTERN KS SATURDAY MORNING AND SPREAD EAST INTO
EASTERN KS BY THE AFTERNOON. THEREFORE POPS HAVE BEEN INCREASED FOR
THE FORECAST AREA SATURDAY AFTERNOON AND SATURDAY NIGHT. THE NAM AND
GFS FORECAST SOUNDINGS HAVE TRENDED WARMER WITH THE BOUNDARY LAYER
SATURDAY WITH SURFACE TEMPS IN THE UPPER 30S THROUGH THE AFTERNOON
ACROSS EAST CENTRAL KS. BECAUSE OF THIS HAVE MOVED THE RAIN/SNOW
LINE BACK NORTHWEST EXPECTING AREAS ALONG AND SOUTH OF THE TURNPIKE
TO SEE MAINLY RAIN THROUGH THE BULK OF THE DAY SATURDAY. ACROSS
NORTH CENTRAL KS...TEMPS LOOK COLD ENOUGH FOR PRECIP TO BE ALL SNOW.
AS THE UPPER WAVE PASSES TO THE EAST EARLY SATURDAY EVENING...THE
COLD AIR SHOULD FILL IN WITH PRECIP CHANGING TO SNOW DURING THE
EVENING. THERE IS SOME UNCERTAINTY IN PRECIP TYPE ACROSS EAST
CENTRAL KS FOR SATURDAY EVENING BECAUSE MODELS SHOW MID LEVEL DRY
AIR LIFTING INTO THE AREA AND DRYING OUT THE DENDRITIC GROWTH ZONE.
WITH NO ICE IN THE CLOUD...THERE COULD BE SIMPLY RAIN FALLING WITH
TEMPS IN THE MID 30S. WITH RAIN EXPECTED INITIALLY SATURDAY AND THE
POTENTIAL FOR A MIX OF PRECIP SATURDAY EVENING...HAVE KNOCKED DOWN
SNOW AMOUNTS ACROSS EAST CENTRAL KS WITH MAYBE AROUND 4 INCHES
POSSIBLE BY SUNDAY AFTERNOON. OTHERWISE IT IS NOT CLEAR WHETHER
SNOWFALL RATES WILL BE ENHANCED BY MESOSCALE FORCING OR IF IT WILL
BE DRIVEN ALL BY SYNOPTIC FORCING. THERE DOES APPEAR TO BE SOME
UPRIGHT INSTABILITY ON SATURDAY WHICH COULD INCREASE SNOWFALL RATES.
AND THE NAM HINTS AT A WEAK TROWAL SATURDAY NIGHT. HOWEVER IT ONLY
REALLY SHOWS UP AROUND 600 MB AND IS NOT VERY DEEP. CONSIDERING THE
SURFACE LOW COULD END UP OVER TN OR MS BY 12Z SUNDAY...AM NOT SURE
THE WARM CONVEYOR BELT WOULD WRAP ALL THE WAY BACK INTO EASTERN KS.
PERHAPS THE ENHANCED QPF FROM THE NAM IS A FUNCTION OF THE UPPER
LEVEL DEFORMATION FROM THE WAVE PROPAGATING EAST. SO FOR FAR
NORTHEAST AND NORTH CENTRAL KS...THE FORECAST IS STILL CALLING FOR
AROUND 5 TO 7 INCHES. HAVE DECIDED TO UPGRADE AREAS WEST OF MHK TO A
WARNING SINCE THEY SHOULD BEGIN TO BE IMPACTED BY THE STORM BY NOON
TOMORROW. SINCE PRECIP MAY END UP BEING MORE RAIN IN EAST CENTRAL KS
AND THE SNOW COULD HOLD OFF UNTIL SATURDAY EVENING...WILL KEEP THE
WATCH GOING FOR AREAS EAST OF MHK AND LET LATER SHIFTS HAVE A LOOK
AT THE NEWER GUIDANCE.
WITH MODELS ADVECTING A LITTLE MORE WARM AIR INTO EASTERN KS...HAVE
BUMPED HIGHS UP TO AROUND 40 IN THE EAST WITH HIGHS NEAR THE
FREEZING MARK ACROSS NORTH CENTRAL KS. LOWS SUNDAY MORNING SHOULD
FALL INTO THE 20S AS NORTHWEST WINDS INCREASE AND BRING COLDER AIR
SOUTH. CLOUD COVER AND BREEZY NORTHWEST WINDS SHOULD KEEP TEMPS FROM
WARMING MUCH ON SUNDAY...SO HIGHS ARE FORECAST TO BE IN THE LOWER TO
MID 30S.
WOLTERS
SUNDAY NIGHT THROUGH FRIDAY...
SECONDARY UPPER TROF SWINGS THROUGH LATE SUNDAY NIGHT AND MONDAY
WITH LIMITED FORCING AND ONLY SHALLOW MOISTURE SO WILL KEEP DRY
FORECAST GOING. NORTHWEST WINDS PERSIST WITH TEMPS OVER THE FRESH
SNOW NOT WARMING MUCH.
SURFACE RIDGE AXIS TAKES RESIDENCE MONDAY NIGHT INTO TUESDAY AS
ZONAL FLOW BEGINS TO TAKE HOLD OF THE SOUTHWESTERN THIRD OF THE
CONUS. SOUTH WINDS KICK IN FOR AT LEAST THE BULK OF THE AREA
WEDNESDAY FOR A MORE SIGNIFICANT WARM-UP...THOUGH MODELS DIVERGE
SOMEWHAT WITH SHORTWAVES COMING SOUTHEAST ACROSS THE NORTHERN PLAINS
AND GREAT LAKES...WHICH COULD LEAVE A MODIFIED BOUNDARY OVER THE
CENTRAL PLAINS. INCREASING LOW LEVEL MOISTURE VIA THE SOUTH WINDS
COMBINED WITH THE CONVERGENCE COULD BE ENOUGH FOR SOME CHANCE FOR
MAINLY RAIN FOR THE LATTER PERIODS. THOUGH CONFIDENCE IS NOT HIGH
GIVEN EASTERLY LOW LEVEL FLOW POTENTIAL...WILL BRING TEMPS UP TO
NEAR LATE MARCH NORMALS.
65
&&
.AVIATION...
IFR CONDITIONS SHOULD CONTINUE THROUGH THE EARLY AFTERNOON HOURS.
THE STRATUS DECK IS BEGINNING TO BREAK UP ACROSS CENTRAL KANSAS
THEREFORE MVFR CONDITIONS ARE EXPECTED AROUND 20Z. THERE MAY BE A
BRIEF PERIOD OF VFR CONDITIONS THIS EVENING BEFORE THE MVFR
CONDITIONS RETURN AGAIN AROUND 07Z. DRIZZLE MAY ALSO DEVELOP
OVERNIGHT AS SOUNDINGS SHOW WEAK LIFT IN A SATURATED LOW LEVEL
LAYER. THE MORE IMPRESSIVE LIFT AND COLUMN SATURATION ASSOCIATED
WITH THE MAIN STORM SYSTEM WILL BEGIN TO EFFECT THE AREA AROUND
15Z. ALTHOUGH CONFIDENCE IN THE START TIME OF PRECIP IS LOW.
THEREFORE LATER SHIFTS WILL MONITOR THE SITUATION AND CONTINUE
UPDATES.
SANDERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
MORNING FOR KSZ011-012-023-024-026-037>040-054>056-058-059.
WINTER STORM WARNING FROM 7 AM SATURDAY TO 7 AM CDT SUNDAY FOR
KSZ008>010-020>022-034>036.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
140 PM CDT FRI MAR 22 2013
...UPDATED WITH A LATE AVIATION DISCUSSION...
.SYNOPSIS...
ISSUED AT 252 AM CDT FRI MAR 22 2013
THE BULK OF THE POLAR JET ENERGY WAS POSITIONED ACROSS THE SOUTHERN
ROCKIES, THROUGH THE SOUTHERN PLAINS, WRAPPING THROUGH THE SOUTHEAST
UNITED STATES JUST SOUTH OF THE NORTHEAST U.S. BROAD CLOSED LOW. A
SECOND SIGNIFICANT UPPER JET WAS DIVING SOUTHWARD ON THE HEELS OF
THE FIRST, INTO THE NORTHWEST PACIFIC REGION COASTLINE. THE MID
LEVELS EXHIBITS COLD 500 MB AIR TEMPERATURES BELOW -20 DEGREES
ACROSS MOST OF THE CONUS. THE AIR ASSOCIATED WITH THE 500 MB TROUGH
ACROSS THE NORTHWEST U.S. WAS -30 TO NEAR -40 DEGREES C. A STRONG
TEMPERATURE GRADIENT REMAINED IN PLACE FROM CENTRAL KANSAS, WHICH
MARKED THE EDGE OF THE FREEZING AT AT THE 850 MB LEVEL...TO THE
TEXAS PANHANDLE WHERE WARM +20 DEGREE C AIR WAS IN PLACE. RAIN AND
SNOW WERE FALLING ACROSS NORTHWEST KANSAS INTO SOUTH CENTRAL
NEBRASKA, ASSOCIATED WITH A STRONG BAROCLINIC ZONE AND ISENTROPIC
LIFT.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 252 AM CDT FRI MAR 22 2013
NUMEROUS SNOW SHOWERS CONTINUE TO DRIFT FROM WEST CENTRAL INTO
CENTRAL KANSAS THIS MORNING. THE HIGHEST CONCENTRATION OF SNOW
SHOWERS WILL MOVE THROUGH THE RUSH CENTER TO STAFFORD AND SAINT JOHNS
AREAS THOUGH 5 AM. AREAS TO THE SOUTH WILL FIND THE SHOWERS REALIZED
AS EITHER RAIN OR SNOW PRECIPITATION TYPE, AS WARMER TEMPERATURES
ARE FOUND NEAR THE OKLAHOMA LINE. BASED ON THE RAPID REFRESH THE
PRECIPITATION SHOULD CLEAR THE AREA BY 11 UTC. HOWEVER, LOW LEVEL
STRATUS WILL PERSIST THROUGH THE MORNING UNTIL THE STRONG MARCH SUN
CAN WARM THE BOUNDARY LAYER SUFFICIENTLY TO INDUCE MIXING. THE
LATEST NAM MODEL SUGGESTS THIS SHOULD OCCUR RAPIDLY BETWEEN 15 AND
18 UTC. AS A RESULT, DRY AIR IN WESTERN KANSAS WILL ALLOW RAPID
WARMING INTO THE 60S BY THE AFTERNOON, WHILE CENTRAL KANSAS COUNTIES
FROM HAYS TO PRATT AND MEDICINE LODGE WILL BE SLOWER TO RESPOND.
WEAK EASTERLY UPSLOPE WINDS SHOULD PERSIST THROUGH THE DAY, BEFORE
TURNING SLIGHTLY MORE SOUTHEASTERLY FOR A FEW HOURS IN RESPONSE TO
SURFACE CYCLOGENESIS OVER EASTERN COLORADO THROUGH THE EVENING AND
INTO TONIGHT.
WITH THE COOL STABLE BOUNDARY LAYER AIRMASS ACROSS CENTRAL KANSAS IN
PLACE, RAPID STRATUS REDEVELOPMENT SHOULD OCCUR AGAIN BEFORE
MIDNIGHT. MODEL CONSENSUS INDICATES WARM ADVECTION PRECIPITATION
CONVECTIVE SHOWERS ARE POSSIBLE THIS EVENING ACROSS THE FAR
SOUTHWEST KANSAS COUNTIES, ASSOCIATED WITH THE NEXT SYNOPTIC SCALE
STORM. CHANCES ARE GOOD THAT THE INITIAL SHOWERS WILL BECOME MORE
NUMEROUS THROUGH THE OVERNIGHT HOURS, AND LIKELY QUICKLY CAUSE
SURFACE TEMPERATURES ACROSS WESTERN KANSAS TO DROP TO THE WET BULB
TEMPERATURE CAUSING A PHASE CHANGE TO SNOW OVERNIGHT. AN INCH OR TWO
OF SNOW COULD BE POSSIBLE ACROSS ANY AREAS OF WEST CENTRAL KANSAS
THROUGH THE INTERSTATE 70 CORRIDOR BY 12Z SATURDAY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 429 AM CDT FRI MAR 22 2013
WINTER STORM STILL THE FOCUS OF THE LONG TERM SECTION...WITH IMPACTS
THE MAIN CHALLENGE...IN TERMS OF TIMING AND SEVERITY...AND WHO WILL
GET THE BRUNT OF THE STORM.
400MB POTENTIAL VORTICITY (PV) STREAM EVIDENT ON RAP ANALYSIS AND
WATER VAPOR LOOP THIS MORNING FROM SOUTHWESTER BRITISH COLUMBIA TO
SOUTHWESTERN IDAHO. THIS STREAM OF HIGH PV AIR WILL AID IN THE
FORMATION OF A MID LEVEL CYCLONE BY EARLY SATURDAY OVER WESTERN
COLORADO. THE INCREASED UPPER TROPOSPHERIC JET STREAK DYNAMICS
ASSOCIATED WITH THE STORM WILL AID IN LOW LEVEL CYCLOGENESIS AS WELL
BY EARLY SATURDAY MORNING. SATURATION WILL OCCUR IN THE LOW LEVELS
WITH INITIAL PRECIPITATION BREAKING OUT LATE IN THE FRIDAY NIGHT
PERIOD INTO EARLY SATURDAY AS WARM, MOIST FRONTOGENESIS INCREASES
DRAMATICALLY IN THE 800-700MB LAYER. AS THE LOWER-MID TROPOSPHERIC
COLUMN SATURATES EARLY SATURDAY...THE VERTICAL THERMODYNAMIC PROFILE
WILL QUICKLY SUPPORT SNOW AS THE PROFILE GOES BELOW ZERO DEGC OVER
MUCH OF SOUTHWEST KANSAS...ESPECIALLY BY 18Z SATURDAY. THE SNOW WILL
INITIALLY BE A VERY WET SNOW AS SURFACE TEMPERATURES WILL BE IN THE
32 TO 35 DEGREE RANGE WITH A PREDOMINANTLY EAST TO EAST-NORTHEAST
SURFACE WIND THROUGH MIDDAY. BY AFTERNOON...SURFACE TEMPERATURES
WILL APPROACH 30 AND LOW LEVEL COLD ADVECTION WILL INCREASE WHICH
WILL ENHANCE THE DROP IN TEMPERATURE...ESPECIALLY WEST OF HIGHWAY
83. THE WINDS WEST OF HIGHWAY 83 WILL BECOME NORTH AND INCREASE TO
25 TO 30 MPH. THERE IS SOME CONCERN THAT GIVEN THE MAGNITUDE OF WIND
AND POTENTIAL ONE HALF TO ONE-INCH PER HOUR SNOWFALL RATES BY LATE
IN THE DAY...THAT WHITE-OUT OR NEAR WHITE-OUT CONDITIONS WILL OCCUR.
THE SNOW WILL BECOME INCREASINGLY SUSCEPTIBLE TO BLOWING AS
TEMPERATURES FALL INTO THE UPPER 20S BY 00Z AS FAR EAST AS HIGHWAY
283 (WAKEENEY TO DODGE CITY TO ASHLAND LINE). TEMPERATURE AND TIME
OF DAY WILL HAVE A HUGE IMPACT ON THE BLOWING AND DRIFTING OF
SNOW...LEADING TO THE NEAR-BLIZZARD OR EVEN BLIZZARD THREAT. IF THE
BRUNT OF THE STORM WAS TO OCCUR DURING THE MIDDLE OF THE DAY WITH
SURFACE TEMPERATURES IN THE 32 TO 34 DEGREE RANGE...THE THREAT FOR
BLOWING SNOW WOULD BE GREATLY REDUCED DUE TO THE VERY WET NATURE AND
COMPOSITION OF SNOW (LARGE, WET AGGREGATE FLAKES VS. DRIER
INDIVIDUAL DENDRITES). THE DENDRITIC GROWTH ZONE (-12C TO -16C) WILL
BE IN THE FAVORED 750-650MB LAYER DURING THE 00-09Z TIME FRAME
SUNDAY IN THE MID LEVEL DEFORMATION ZONE WHICH WILL AID IN SLIGHTLY
HIGHER SNOWFALL RATIO THAN WHAT WOULD TYPICALLY BE EXPECTED FOR LATE
MARCH...SO THIS IS SOMETHING TO KEEP IN MIND AS WELL.
GIVEN ALL OF THE ABOVE MENTIONED...AND WITH THE MID LEVEL
FRONTOGENETIC ZONE LIKELY JUST FAR ENOUGH SOUTH TO IMPACT THE
SOUTHERN COUNTIES (USING THE ECMWF AND CANADIAN GEM MORE SOUTHERN
SCENARIO)...WILL ISSUE A WINTER WEATHER ADVISORY IN THE SOUTHERN
COUNTIES NOT CURRENTLY IN THE WINTER STORM WATCH (ROUGHLY ARKANSAS
RIVER SOUTH TO THE OKLAHOMA BORDER). AS FAR AS STORM TOTAL SNOWFALL
AMOUNTS GO...THIS IS STILL A VERY DIFFICULT FORECAST AND WILL LIKELY
COME DOWN TO THE MESOSCALE COMPONENTS OF THE STORM ITSELF (AS IS
TYPICALLY THE CASE). THAT BEING SAID...IT STILL LOOKS LIKE THE
NORTHERN HALF OF THE FORECAST AREA (ARKANSAS RIVER TO INTERSTATE 700
WILL SEE TOTAL SNOWFALL IN THE 4 TO 7 INCH RANGE WITH A FEW 8 INCH
AMOUNTS POSSIBLE IN SOME SPOTS. FROM THE ARKANSAS RIVER SOUTH TO THE
OKLAHOMA BORDER...3 TO 5 INCHES IS THE FORECAST.
THE STORM WILL QUICKLY EXIT EAST SUNDAY MORNING WITH SOME REMNANT
LIGHT BLOWING AND DRIFTING THROUGH THE MORNING HOURS AFTER SUNRISE
SUNDAY. THE MARCH SUN WILL AID IN SNOWMELT ON ROAD SURFACES...BUT IT
WILL HAVE SOME WORK TO DO AS STRONG COLD ADVECTION WILL CONTINUE
THROUGH THE DAY AND 2-METER TEMPERATURES WILL STAY IN THE 20S MOST
OF THE DAY.
UNFORTUNATELY...HAVE HAD NO TIME TO ADDRESS THE FORECAST BEYOND
SUNDAY AND RUNNING WITH THE LATEST ALLBLEND GUIDANCE WHICH CALLS FOR
A SLOW WARM-UP MONDAY AND TUESDAY (30S AND 40S). BY WEDNESDAY...WE
SHOULD SEE A FAIRLY DRAMATIC WARM-UP BACK INTO THE 50S AND PERHAPS
60S. AFTER THIS BRIEF WARM-UP BACK TO CLIMO...WE WILL MOST LIKELY
ENTER ANOTHER COLD SPELL GOING INTO THE DAY 7-10 TIME FRAME AS WE
END THE MONTH OF MARCH.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 135 PM CDT FRI MAR 22 2013
FOR THE REST OF TODAY, SKIES WILL BE MOSTLY CLEAR AS A SMALL WEDGE
OF HIGH PRESSURE CONTROLS THE AREA. A LARGE UPPER LEVEL SYSTEM IS
MOVING TOWARD WESTERN KANSAS FROM THE WEST. WINDS WILL BASICALLY
BE LIGHT AND VARIABLE THROUGH 23Z, THEN BECOME EAST AT AROUND 15 KNOTS.
OVERNIGHT, LOW LEVEL MOISTURE WILL RIDE UP FROM THE SOUTH AND
SOUTHEAST, AND DEVELOP INTO IFR CIGS AFTER 09Z TONIGHT. THE BIGGER
SHOW OF DRIZZLE AND THEN SNOW COMES LATER ON SATURDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 34 35 23 30 / 10 90 90 10
GCK 32 33 21 30 / 10 90 90 0
EHA 36 37 21 34 / 10 90 80 10
LBL 37 38 23 34 / 10 90 80 10
HYS 29 31 23 30 / 90 90 90 30
P28 35 38 28 35 / 10 90 80 40
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM 1 AM CDT /MIDNIGHT MDT/ SATURDAY THROUGH
SUNDAY MORNING FOR KSZ030-031-043>046-061>066.
WINTER WEATHER ADVISORY FROM 10 AM SATURDAY TO 7 AM CDT SUNDAY
FOR KSZ074>081-084>090.
&&
$$
SYNOPSIS...RUSSELL
SHORT TERM...RUSSELL
LONG TERM...UMSCHEID
AVIATION...BURKE
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
752 AM CDT FRI MAR 22 2013
...UPDATED AVIATION SECTION...
.SYNOPSIS...
ISSUED AT 252 AM CDT FRI MAR 22 2013
THE BULK OF THE POLAR JET ENERGY WAS POSITIONED ACROSS THE SOUTHERN
ROCKIES, THROUGH THE SOUTHERN PLAINS, WRAPPING THROUGH THE SOUTHEAST
UNITED STATES JUST SOUTH OF THE NORTHEAST U.S. BROAD CLOSED LOW. A
SECOND SIGNIFICANT UPPER JET WAS DIVING SOUTHWARD ON THE HEELS OF
THE FIRST, INTO THE NORTHWEST PACIFIC REGION COASTLINE. THE MID
LEVELS EXHIBITS COLD 500 MB AIR TEMPERATURES BELOW -20 DEGREES
ACROSS MOST OF THE CONUS. THE AIR ASSOCIATED WITH THE 500 MB TROUGH
ACROSS THE NORTHWEST U.S. WAS -30 TO NEAR -40 DEGREES C. A STRONG
TEMPERATURE GRADIENT REMAINED IN PLACE FROM CENTRAL KANSAS, WHICH
MARKED THE EDGE OF THE FREEZING AT AT THE 850 MB LEVEL...TO THE
TEXAS PANHANDLE WHERE WARM +20 DEGREE C AIR WAS IN PLACE. RAIN AND
SNOW WERE FALLING ACROSS NORTHWEST KANSAS INTO SOUTH CENTRAL
NEBRASKA, ASSOCIATED WITH A STRONG BAROCLINIC ZONE AND ISENTROPIC
LIFT.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 252 AM CDT FRI MAR 22 2013
NUMEROUS SNOW SHOWERS CONTINUE TO DRIFT FROM WEST CENTRAL INTO
CENTRAL KANSAS THIS MORNING. THE HIGHEST CONCENTRATION OF SNOW
SHOWERS WILL MOVE THROUGH THE RUSH CENTER TO STAFFORD AND SAINT JOHNS
AREAS THOUGH 5 AM. AREAS TO THE SOUTH WILL FIND THE SHOWERS REALIZED
AS EITHER RAIN OR SNOW PRECIPITATION TYPE, AS WARMER TEMPERATURES
ARE FOUND NEAR THE OKLAHOMA LINE. BASED ON THE RAPID REFRESH THE
PRECIPITATION SHOULD CLEAR THE AREA BY 11 UTC. HOWEVER, LOW LEVEL
STRATUS WILL PERSIST THROUGH THE MORNING UNTIL THE STRONG MARCH SUN
CAN WARM THE BOUNDARY LAYER SUFFICIENTLY TO INDUCE MIXING. THE
LATEST NAM MODEL SUGGESTS THIS SHOULD OCCUR RAPIDLY BETWEEN 15 AND
18 UTC. AS A RESULT, DRY AIR IN WESTERN KANSAS WILL ALLOW RAPID
WARMING INTO THE 60S BY THE AFTERNOON, WHILE CENTRAL KANSAS COUNTIES
FROM HAYS TO PRATT AND MEDICINE LODGE WILL BE SLOWER TO RESPOND.
WEAK EASTERLY UPSLOPE WINDS SHOULD PERSIST THROUGH THE DAY, BEFORE
TURNING SLIGHTLY MORE SOUTHEASTERLY FOR A FEW HOURS IN RESPONSE TO
SURFACE CYCLOGENESIS OVER EASTERN COLORADO THROUGH THE EVENING AND
INTO TONIGHT.
WITH THE COOL STABLE BOUNDARY LAYER AIRMASS ACROSS CENTRAL KANSAS IN
PLACE, RAPID STRATUS REDEVELOPMENT SHOULD OCCUR AGAIN BEFORE
MIDNIGHT. MODEL CONSENSUS INDICATES WARM ADVECTION PRECIPITATION
CONVECTIVE SHOWERS ARE POSSIBLE THIS EVENING ACROSS THE FAR
SOUTHWEST KANSAS COUNTIES, ASSOCIATED WITH THE NEXT SYNOPTIC SCALE
STORM. CHANCES ARE GOOD THAT THE INITIAL SHOWERS WILL BECOME MORE
NUMEROUS THROUGH THE OVERNIGHT HOURS, AND LIKELY QUICKLY CAUSE
SURFACE TEMPERATURES ACROSS WESTERN KANSAS TO DROP TO THE WET BULB
TEMPERATURE CAUSING A PHASE CHANGE TO SNOW OVERNIGHT. AN INCH OR TWO
OF SNOW COULD BE POSSIBLE ACROSS ANY AREAS OF WEST CENTRAL KANSAS
THROUGH THE INTERSTATE 70 CORRIDOR BY 12Z SATURDAY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 429 AM CDT FRI MAR 22 2013
WINTER STORM STILL THE FOCUS OF THE LONG TERM SECTION...WITH IMPACTS
THE MAIN CHALLENGE...IN TERMS OF TIMING AND SEVERITY...AND WHO WILL
GET THE BRUNT OF THE STORM.
400MB POTENTIAL VORTICITY (PV) STREAM EVIDENT ON RAP ANALYSIS AND
WATER VAPOR LOOP THIS MORNING FROM SOUTHWESTER BRITISH COLUMBIA TO
SOUTHWESTERN IDAHO. THIS STREAM OF HIGH PV AIR WILL AID IN THE
FORMATION OF A MID LEVEL CYCLONE BY EARLY SATURDAY OVER WESTERN
COLORADO. THE INCREASED UPPER TROPOSPHERIC JET STREAK DYNAMICS
ASSOCIATED WITH THE STORM WILL AID IN LOW LEVEL CYCLOGENESIS AS WELL
BY EARLY SATURDAY MORNING. SATURATION WILL OCCUR IN THE LOW LEVELS
WITH INITIAL PRECIPITATION BREAKING OUT LATE IN THE FRIDAY NIGHT
PERIOD INTO EARLY SATURDAY AS WARM, MOIST FRONTOGENESIS INCREASES
DRAMATICALLY IN THE 800-700MB LAYER. AS THE LOWER-MID TROPOSPHERIC
COLUMN SATURATES EARLY SATURDAY...THE VERTICAL THERMODYNAMIC PROFILE
WILL QUICKLY SUPPORT SNOW AS THE PROFILE GOES BELOW ZERO DEGC OVER
MUCH OF SOUTHWEST KANSAS...ESPECIALLY BY 18Z SATURDAY. THE SNOW WILL
INITIALLY BE A VERY WET SNOW AS SURFACE TEMPERATURES WILL BE IN THE
32 TO 35 DEGREE RANGE WITH A PREDOMINANTLY EAST TO EAST-NORTHEAST
SURFACE WIND THROUGH MIDDAY. BY AFTERNOON...SURFACE TEMPERATURES
WILL APPROACH 30 AND LOW LEVEL COLD ADVECTION WILL INCREASE WHICH
WILL ENHANCE THE DROP IN TEMPERATURE...ESPECIALLY WEST OF HIGHWAY
83. THE WINDS WEST OF HIGHWAY 83 WILL BECOME NORTH AND INCREASE TO
25 TO 30 MPH. THERE IS SOME CONCERN THAT GIVEN THE MAGNITUDE OF WIND
AND POTENTIAL ONE HALF TO ONE-INCH PER HOUR SNOWFALL RATES BY LATE
IN THE DAY...THAT WHITE-OUT OR NEAR WHITE-OUT CONDITIONS WILL OCCUR.
THE SNOW WILL BECOME INCREASINGLY SUSCEPTIBLE TO BLOWING AS
TEMPERATURES FALL INTO THE UPPER 20S BY 00Z AS FAR EAST AS HIGHWAY
283 (WAKEENEY TO DODGE CITY TO ASHLAND LINE). TEMPERATURE AND TIME
OF DAY WILL HAVE A HUGE IMPACT ON THE BLOWING AND DRIFTING OF
SNOW...LEADING TO THE NEAR-BLIZZARD OR EVEN BLIZZARD THREAT. IF THE
BRUNT OF THE STORM WAS TO OCCUR DURING THE MIDDLE OF THE DAY WITH
SURFACE TEMPERATURES IN THE 32 TO 34 DEGREE RANGE...THE THREAT FOR
BLOWING SNOW WOULD BE GREATLY REDUCED DUE TO THE VERY WET NATURE AND
COMPOSITION OF SNOW (LARGE, WET AGGREGATE FLAKES VS. DRIER
INDIVIDUAL DENDRITES). THE DENDRITIC GROWTH ZONE (-12C TO -16C) WILL
BE IN THE FAVORED 750-650MB LAYER DURING THE 00-09Z TIME FRAME
SUNDAY IN THE MID LEVEL DEFORMATION ZONE WHICH WILL AID IN SLIGHTLY
HIGHER SNOWFALL RATIO THAN WHAT WOULD TYPICALLY BE EXPECTED FOR LATE
MARCH...SO THIS IS SOMETHING TO KEEP IN MIND AS WELL.
GIVEN ALL OF THE ABOVE MENTIONED...AND WITH THE MID LEVEL
FRONTOGENETIC ZONE LIKELY JUST FAR ENOUGH SOUTH TO IMPACT THE
SOUTHERN COUNTIES (USING THE ECMWF AND CANADIAN GEM MORE SOUTHERN
SCENARIO)...WILL ISSUE A WINTER WEATHER ADVISORY IN THE SOUTHERN
COUNTIES NOT CURRENTLY IN THE WINTER STORM WATCH (ROUGHLY ARKANSAS
RIVER SOUTH TO THE OKLAHOMA BORDER). AS FAR AS STORM TOTAL SNOWFALL
AMOUNTS GO...THIS IS STILL A VERY DIFFICULT FORECAST AND WILL LIKELY
COME DOWN TO THE MESOSCALE COMPONENTS OF THE STORM ITSELF (AS IS
TYPICALLY THE CASE). THAT BEING SAID...IT STILL LOOKS LIKE THE
NORTHERN HALF OF THE FORECAST AREA (ARKANSAS RIVER TO INTERSTATE 700
WILL SEE TOTAL SNOWFALL IN THE 4 TO 7 INCH RANGE WITH A FEW 8 INCH
AMOUNTS POSSIBLE IN SOME SPOTS. FROM THE ARKANSAS RIVER SOUTH TO THE
OKLAHOMA BORDER...3 TO 5 INCHES IS THE FORECAST.
THE STORM WILL QUICKLY EXIT EAST SUNDAY MORNING WITH SOME REMNANT
LIGHT BLOWING AND DRIFTING THROUGH THE MORNING HOURS AFTER SUNRISE
SUNDAY. THE MARCH SUN WILL AID IN SNOWMELT ON ROAD SURFACES...BUT IT
WILL HAVE SOME WORK TO DO AS STRONG COLD ADVECTION WILL CONTINUE
THROUGH THE DAY AND 2-METER TEMPERATURES WILL STAY IN THE 20S MOST
OF THE DAY.
UNFORTUNATELY...HAVE HAD NO TIME TO ADDRESS THE FORECAST BEYOND
SUNDAY AND RUNNING WITH THE LATEST ALLBLEND GUIDANCE WHICH CALLS FOR
A SLOW WARM-UP MONDAY AND TUESDAY (30S AND 40S). BY WEDNESDAY...WE
SHOULD SEE A FAIRLY DRAMATIC WARM-UP BACK INTO THE 50S AND PERHAPS
60S. AFTER THIS BRIEF WARM-UP BACK TO CLIMO...WE WILL MOST LIKELY
ENTER ANOTHER COLD SPELL GOING INTO THE DAY 7-10 TIME FRAME AS WE
END THE MONTH OF MARCH.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 746 AM CDT FRI MAR 22 2013
MAIN IMPACT ON AVIATION WILL BE THE DEVELOPMENT OF IFR/LIFR
CEILINGS OVERNIGHT TONIGHT AS LOW PRESSURE DEVELOPS IN ADVANCE OF
THE APPROACHING WINTER STORM. CEILINGS WILL DETERIORATE QUICKLY
AROUND THE 08-10Z TIME FRAME AT DDC, GCK, AND HYS. PRECIPITATION
IN THE FORM OF SNOW WILL DEVELOP SHORTLY AFTER DAYBREAK SATURDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 52 35 35 23 / 10 80 90 90
GCK 52 33 33 21 / 10 90 90 90
EHA 56 37 37 21 / 20 90 90 80
LBL 56 38 38 23 / 10 80 90 80
HYS 48 30 31 23 / 10 90 90 90
P28 52 36 38 28 / 10 50 90 80
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
KSZ030-031-043>046-061>066.
WINTER WEATHER ADVISORY FROM 10 AM SATURDAY TO 7 AM CDT SUNDAY
FOR KSZ074>081-084>090.
&&
$$
SYNOPSIS...RUSSELL
SHORT TERM...RUSSELL
LONG TERM...UMSCHEID
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
431 AM CDT FRI MAR 22 2013
...UPDATED LONG TERM SECTION...
.SYNOPSIS...
ISSUED AT 252 AM CDT FRI MAR 22 2013
THE BULK OF THE POLAR JET ENERGY WAS POSITIONED ACROSS THE SOUTHERN
ROCKIES, THROUGH THE SOUTHERN PLAINS, WRAPPING THROUGH THE SOUTHEAST
UNITED STATES JUST SOUTH OF THE NORTHEAST U.S. BROAD CLOSED LOW. A
SECOND SIGNIFICANT UPPER JET WAS DIVING SOUTHWARD ON THE HEELS OF
THE FIRST, INTO THE NORTHWEST PACIFIC REGION COASTLINE. THE MID
LEVELS EXHIBITES COLD 500 MB AIR TEMPERATURES BELOW -20 DEGREES
ACROSS MOST OF THE CONUS. THE AIR ASSOCIATED WITH THE 500 MB TROUGH
ACROSS THE NORTHWEST U.S. WAS -30 TO NEAR -40 DEGREES C. A STRONG
TEMPERATURE GRADIENT REMAINED IN PLACE FROM CENTRAL KANSAS, WHICH
MARKED THE EDGE OF THE FREEZING AT AT THE 850 MB LEVEL...TO THE
TEXAS PANHANDLE WHERE WARM +20 DEGREE C AIR WAS IN PLACE. RAIN AND
SNOW WERE FALLING ACROSS NORTHWEST KANSAS INTO SOUTH CENTRAL
NEBRASKA, ASSOCIATED WITH A STRONG BAROCLINIC ZONE AND ISENTROPIC
LIFT.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 252 AM CDT FRI MAR 22 2013
NUMEROUS SNOW SHOWERS CONTINUE TO DRIFT FROM WEST CENTRAL INTO
CENTRAL KANSAS THIS MORNING. THE HIGHEST CONCENTRATION OF SNOW
SHOWERS WILL MOVE THROUGH THE RUSH CENTER TO STAFFORD AND SAINT JOHNS
AREAS THOUGH 5 AM. AREAS TO THE SOUTH WILL FIND THE SHOWERS REALIZED
AS EITHER RAIN OR SNOW PRECIPITATION TYPE, AS WARMER TEMPERATURES
ARE FOUND NEAR THE OKLAHOMA LINE. BASED ON THE RAPID REFRESH THE
PRECIPITATION SHOULD CLEAR THE AREA BY 11 UTC. HOWEVER, LOW LEVEL
STRATUS WILL PERSIST THROUGH THE MORNING UNTIL THE STRONG MARCH SUN
CAN WARM THE BOUNDARY LAYER SUFFICIENTLY TO INDUCE MIXING. THE
LATEST NAM MODEL SUGGESTS THIS SHOULD OCCUR RAPIDLY BETWEEN 15 AND
18 UTC. AS A RESULT, DRY AIR IN WESTERN KANSAS WILL ALLOW RAPID
WARMING INTO THE 60S BY THE AFTERNOON, WHILE CENTRAL KANSAS COUNTIES
FROM HAYS TO PRATT AND MEDICINE LODGE WILL BE SLOWER TO RESPOND.
WEAK EASTERLY UPSLOPE WINDS SHOULD PERSIST THROUGH THE DAY, BEFORE
TURNING SLIGHTLY MORE SOUTHEASTERLY FOR A FEW HOURS IN RESPONSE TO
SURFACE CYCLOGENESIS OVER EASTERN COLORADO THROUGH THE EVENING AND
INTO TONIGHT.
WITH THE COOL STABLE BOUNDARY LAYER AIRMASS ACROSS CENTRAL KANSAS IN
PLACE, RAPID STRATUS REDEVELOPMENT SHOULD OCCUR AGAIN BEFORE
MIDNIGHT. MODEL CONSENSUS INDICATES WARM ADVECTION PRECIPITATION
CONVECTIVE SHOWERS ARE POSSIBLE THIS EVENING ACROSS THE FAR
SOUTHWEST KANSAS COUNTIES, ASSOCIATED WITH THE NEXT SYNOPTIC SCALE
STORM. CHANCES ARE GOOD THAT THE INITIAL SHOWERS WILL BECOME MORE
NUMEROUS THROUGH THE OVERNIGHT HOURS, AND LIKELY QUICKLY CAUSE
SURFACE TEMPERATURES ACROSS WESTERN KANSAS TO DROP TO THE WET BULB
TEMPERATURE CAUSING A PHASE CHANGE TO SNOW OVERNIGHT. AN INCH OR TWO
OF SNOW COULD BE POSSIBLE ACROSS ANY AREAS OF WEST CENTRAL KANSAS
THROUGH THE INTERSTATE 70 CORRIDOR BY 12Z SATURDAY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 429 AM CDT FRI MAR 22 2013
WINTER STORM STILL THE FOCUS OF THE LONG TERM SECTION...WITH IMPACTS
THE MAIN CHALLENGE...IN TERMS OF TIMING AND SEVERITY...AND WHO WILL
GET THE BRUNT OF THE STORM.
400MB POTENTIAL VORTICITY (PV) STREAM EVIDENT ON RAP ANALYSIS AND
WATER VAPOR LOOP THIS MORNING FROM SOUTHWESTER BRITISH COLUMBIA TO
SOUTHWESTERN IDAHO. THIS STREAM OF HIGH PV AIR WILL AID IN THE
FORMATION OF A MID LEVEL CYCLONE BY EARLY SATURDAY OVER WESTERN
COLORADO. THE INCREASED UPPER TROPOSPHERIC JET STREAK DYNAMICS
ASSOCIATED WITH THE STORM WILL AID IN LOW LEVEL CYCLOGENESIS AS WELL
BY EARLY SATURDAY MORNING. SATURATION WILL OCCUR IN THE LOW LEVELS
WITH INITIAL PRECIPITATION BREAKING OUT LATE IN THE FRIDAY NIGHT
PERIOD INTO EARLY SATURDAY AS WARM, MOIST FRONTOGENESIS INCREASES
DRAMATICALLY IN THE 800-700MB LAYER. AS THE LOWER-MID TROPOSPHERIC
COLUMN SATURATES EARLY SATURDAY...THE VERTICAL THERMODYNAMIC PROFILE
WILL QUICKLY SUPPORT SNOW AS THE PROFILE GOES BELOW ZERO DEGC OVER
MUCH OF SOUTHWEST KANSAS...ESPECIALLY BY 18Z SATURDAY. THE SNOW WILL
INITIALLY BE A VERY WET SNOW AS SURFACE TEMPERATURES WILL BE IN THE
32 TO 35 DEGREE RANGE WITH A PREDOMINANTLY EAST TO EAST-NORTHEAST
SURFACE WIND THROUGH MIDDAY. BY AFTERNOON...SURFACE TEMPERATURES
WILL APPROACH 30 AND LOW LEVEL COLD ADVECTION WILL INCREASE WHICH
WILL ENHANCE THE DROP IN TEMPERATURE...ESPECIALLY WEST OF HIGHWAY
83. THE WINDS WEST OF HIGHWAY 83 WILL BECOME NORTH AND INCREASE TO
25 TO 30 MPH. THERE IS SOME CONCERN THAT GIVEN THE MAGNITUDE OF WIND
AND POTENTIAL ONE HALF TO ONE-INCH PER HOUR SNOWFALL RATES BY LATE
IN THE DAY...THAT WHITE-OUT OR NEAR WHITE-OUT CONDITIONS WILL OCCUR.
THE SNOW WILL BECOME INCREASINGLY SUSCEPTIBLE TO BLOWING AS
TEMPERATURES FALL INTO THE UPPER 20S BY 00Z AS FAR EAST AS HIGHWAY
283 (WAKEENEY TO DODGE CITY TO ASHLAND LINE). TEMPERATURE AND TIME
OF DAY WILL HAVE A HUGE IMPACT ON THE BLOWING AND DRIFTING OF
SNOW...LEADING TO THE NEAR-BLIZZARD OR EVEN BLIZZARD THREAT. IF THE
BRUNT OF THE STORM WAS TO OCCUR DURING THE MIDDLE OF THE DAY WITH
SURFACE TEMPERATURES IN THE 32 TO 34 DEGREE RANGE...THE THREAT FOR
BLOWING SNOW WOULD BE GREATLY REDUCED DUE TO THE VERY WET NATURE AND
COMPOSITION OF SNOW (LARGE, WET AGGREGATE FLAKES VS. DRIER
INDIVIDUAL DENDRITES). THE DENDRITIC GROWTH ZONE (-12C TO -16C) WILL
BE IN THE FAVORED 750-650MB LAYER DURING THE 00-09Z TIME FRAME
SUNDAY IN THE MID LEVEL DEFORMATION ZONE WHICH WILL AID IN SLIGHTLY
HIGHER SNOWFALL RATIO THAN WHAT WOULD TYPICALLY BE EXPECTED FOR LATE
MARCH...SO THIS IS SOMETHING TO KEEP IN MIND AS WELL.
GIVEN ALL OF THE ABOVE MENTIONED...AND WITH THE MID LEVEL
FRONTOGENETIC ZONE LIKELY JUST FAR ENOUGH SOUTH TO IMPACT THE
SOUTHERN COUNTIES (USING THE ECMWF AND CANADIAN GEM MORE SOUTHERN
SCENARIO)...WILL ISSUE A WINTER WEATHER ADVISORY IN THE SOUTHERN
COUNTIES NOT CURRENTLY IN THE WINTER STORM WATCH (ROUGHLY ARKANSAS
RIVER SOUTH TO THE OKLAHOMA BORDER). AS FAR AS STORM TOTAL SNOWFALL
AMOUNTS GO...THIS IS STILL A VERY DIFFICULT FORECAST AND WILL LIKELY
COME DOWN TO THE MESOSCALE COMPONENTS OF THE STORM ITSELF (AS IS
TYPICALLY THE CASE). THAT BEING SAID...IT STILL LOOKS LIKE THE
NORTHERN HALF OF THE FORECAST AREA (ARKANSAS RIVER TO INTERSTATE 700
WILL SEE TOTAL SNOWFALL IN THE 4 TO 7 INCH RANGE WITH A FEW 8 INCH
AMOUNTS POSSIBLE IN SOME SPOTS. FROM THE ARKANSAS RIVER SOUTH TO THE
OKLAHOMA BORDER...3 TO 5 INCHES IS THE FORECAST.
THE STORM WILL QUICKLY EXIT EAST SUNDAY MORNING WITH SOME REMNANT
LIGHT BLOWING AND DRIFTING THROUGH THE MORNING HOURS AFTER SUNRISE
SUNDAY. THE MARCH SUN WILL AID IN SNOWMELT ON ROAD SURFACES...BUT IT
WILL HAVE SOME WORK TO DO AS STRONG COLD ADVECTION WILL CONTINUE
THROUGH THE DAY AND 2-METER TEMPERATURES WILL STAY IN THE 20S MOST
OF THE DAY.
UNFORTUNATELY...HAVE HAD NO TIME TO ADDRESS THE FORECAST BEYOND
SUNDAY AND RUNNING WITH THE LATEST ALLBLEND GUIDANCE WHICH CALLS FOR
A SLOW WARM-UP MONDAY AND TUESDAY (30S AND 40S). BY WEDNESDAY...WE
SHOULD SEE A FAIRLY DRAMATIC WARM-UP BACK INTO THE 50S AND PERHAPS
60S. AFTER THIS BRIEF WARM-UP BACK TO CLIMO...WE WILL MOST LIKELY
ENTER ANOTHER COLD SPELL GOING INTO THE DAY 7-10 TIME FRAME AS WE
END THE MONTH OF MARCH.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 110 AM CDT FRI MAR 22 2013
RAPIDLY DEVELOPING STRATUS WILL LIKELY SOON BECOME WIDESPREAD
ACROSS MOST OF CENTRAL AND SOUTHWEST KANSAS. PERIODS OF RAIN/SNOW
SHOWERS ARE LIKELY AT KHYS THROUGH AROUND 10Z AS AN UPPER LEVEL
SHORTWAVE LIFTS THROUGH THE REGION. AS THE PRECIPITATION CLEARS BY
12Z AND STRONG INSOLATION DIMINISHES THE STRATUS, VFR CONDITIONS
ARE EXPECTED THROUGH EARLY FRIDAY EVENING WHEN THE EFFECTS OF THE
NEXT SYNOPTIC SCALE STORM BEGIN TO DEVELOP AS SCATTERED SHOWERS
AND DEVELOPING STRATUS ONCE AGAIN.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 52 35 35 23 / 10 80 90 90
GCK 52 33 33 21 / 10 90 90 90
EHA 56 37 37 21 / 20 90 90 80
LBL 56 38 38 23 / 10 80 90 80
HYS 48 30 31 23 / 10 90 90 90
P28 52 36 38 28 / 10 50 90 80
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
KSZ030-031-043>046-061>066.
WINTER WEATHER ADVISORY FROM 10 AM SATURDAY TO 7 AM CDT SUNDAY
FOR KSZ074>081-084>090.
&&
$$
SYNOPSIS...RUSSELL
SHORT TERM...RUSSELL
LONG TERM...UMSCHEID
AVIATION...RUSSELL
AREA FORECAST DISCUSSION
NWS WICHITA KS
342 AM CDT FRI MAR 22 2013
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 341 AM CDT FRI MAR 22 2013
FORECAST HIGHLIGHTS FOCUS AROUND FREEZING DRIZZLE CHANCES THIS
MORNING...WITH POTENTIALLY HEAVY SNOW SATURDAY-SATURDAY NIGHT.
A FAST MOVING SHORTWAVE APPROACHING FROM THE WEST IN CONCERT WITH A
SUBTLE 850-700MB TROUGH/CONVERGENCE ZONE AND SATURATED LOW-LEVELS IS
RESULTING IN PATCHY LIGHT FREEZING DRIZZLE EARLY THIS MORNING OVER
GENERALLY THE NORTHEAST 1/4 OF KS. GIVEN LATEST OBSERVATIONS AND
SHORT-TERM GUIDANCE...ANTICIPATE THIS ACTIVITY WILL AFFECT FAR
NORTHEAST/EAST PORTIONS OF THE FORECAST AREA EARLY THIS
MORNING...GENERALLY EAST/NORTHEAST OF A LINE EXTENDING FROM
SALINA-HILLSBORO-EUREKA-CHANUTE. GIVEN RELATIVELY WARM PAVEMENT
TEMPERATURES...NOT ANTICIPATING WIDESPREAD PROBLEMS ON
ROADS...ALTHOUGH BRIDGE DECKS AND OTHER ELEVATED SURFACES MAY BE
SLICK. NOT ANTICIPATING ISSUING A WINTER WEATHER ADVISORY.
ADDITIONALLY...PATCHY LIGHT SNOW WILL AFFECT PRIMARILY
CENTRAL/EAST-CENTRAL KS THROUGH EARLY TO MID MORNING...ASSOCIATED
WITH SATURATED MID-LEVELS AHEAD OF APPROACHING SHORTWAVE. SNOW
ACCUMULATIONS WILL LIKELY REMAIN WELL UNDER ONE-HALF INCH.
FURTHERMORE...LOOSELY ORGANIZED BAND OF SHOWERS/THUNDERSTORMS OVER
NORTHERN OK...ASSOCIATED WITH 850-700MB WARM/MOIST ADVECTION...WILL
LIKELY REMAIN SOUTH OF THE KS/OK BORDER AS ACTIVITY SHIFTS EAST
EARLY THIS MORNING.
ATTENTION THEN TURNS TO POTENTIAL WINTER STORM TO AFFECT THE REGION
SATURDAY-SATURDAY NIGHT...AS A SHORTWAVE CURRENTLY OVER THE PACIFIC
NORTHWEST DIVES SOUTHEAST AND STRENGTHENS. DESPITE SOME MINOR TO
MODEST DIFFERENCES IN TRACK AND INTENSITY...MODELS HAVE BEEN
TRENDING INTO BETTER AGREEMENT. IF THERE IS AN OUTLIER...IT`S THE
SLIGHTLY FASTER AND NOT QUITE AS AMPLIFIED GFS SOLUTION...WITH ALL
OTHER MODELS A TAD SLOWER AND DEEPER. MODEL CONSENSUS STILL
BULLSEYES CENTRAL/EAST-CENTRAL KS WITH THE GREATEST ACCUMULATIONS.
GIVEN EXPECTED STRONG FRONTOGENESIS...COUPLED FORCING AND DECENT
SNOW GROWTH ZONE LAPSE RATES...EXPECTING 4-7 INCHES GENERALLY NORTH
OF HIGHWAY 50. FURTHER SOUTH ACROSS SOUTH-CENTRAL/SOUTHEAST KS...A
RAIN/SNOW MIX WILL CUT INTO SNOW AMOUNTS...WITH ACCUMULATIONS OF 1-4
INCHES...LEAST NEAR THE KS/OK BORDER. OTHER THAN PATCHY POCKETS OF
SLEET...PREDOMINANT PRECIPITATION TYPES WILL LIKELY EITHER BE RAIN
OR SNOW GIVEN EXPECTED THERMAL PROFILES.
IT SHOULD BE SAID THERE DOES REMAIN SOME UNCERTAINTY...NAMELY THE
NAM SOLUTION...WHICH WOULD SUGGEST A SWATCH OF HEAVIER SNOW ALONG
THE TURNPIKE AND JUST SOUTHEAST SATURDAY NIGHT. GIVEN ITS TENDENCY
FOR EMBELLISHMENT BEYOND 36 HOURS...WILL NOT BITE JUST YET.
HEADLINES-WISE...WILL EXPAND WINTER STORM WATCH A BIT FURTHER EAST
TO INCLUDE HARVEY-MARION-CHASE COUNTIES. GIVEN LATEST 00Z ECMWF NOT
TRENDING SOUTH...WILL NOT EXPAND WATCH INTO SOUTHERN KS.
ALSO...GIVEN STILL SOME WOBBLE IN THE STORM`S TRACK AND
INTENSITY...WILL LET THE DAY SHIFT MAKE THE CALL ON WINTER STORM
WARNINGS AND ADVISORIES. SNOW SHOULD COME TO AN END SOMETIME LATE
SATURDAY NIGHT OR SUNDAY MORNING OVER EASTERN KS.
ADK
.LONG TERM...(MONDAY THROUGH THURSDAY NIGHT)
ISSUED AT 341 CDT FRI MAR 22 2013
A COLD EARLY TO MID WEEK IS ANTICIPATED...AS LONGWAVE TROUGHING
PERSISTS ACROSS THE CENTRAL AND EASTERN CONUS. GFS/ECMWF CONSENSUS
SUGGESTS BUILDING HEIGHTS/THICKNESS BY MID TO LATE WEEK...WHICH
SHOULD ALLOW TEMPERATURES TO AT LEAST CLIMB INTO THE 50S...WHICH
WOULD GET THEM CLOSER TO NORMAL IN THE 50S-60S.
ADK
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1145 PM CDT THU MAR 21 2013
AVIATION CONCERNS REMAIN LOW CIGS ALONG WITH SOME FREEZING DRIZZLE
POTENTIAL TONIGHT INTO FRI MORNING.
MVFR CIGS CONTINUE TO WORK WEST AND ARE JUST ABOUT READY TO GET
INTO KRSL. CURRENT THINKING IS THAT THESE CIGS WILL CONTINUE TO
LOWER OVERNIGHT WITH WIDESPREAD IFR CIGS LIKELY AFTER 08Z. THE
DRIZZLE THAT HAS OCCURRED SO FAR OVER NORTHEAST KS AND NW MO IS IN
AN AREA OF LOW LEVEL ISENTROPIC LIFT ALONG THE 285K SURFACE. IN FACT
THE LATEST RUC ANALYSIS IS SHOWING A COLD POCKET ALONG THIS SURFACE
RIGHT OVER FAR NORTHEAST KS WHICH IS LIKELY CONTRIBUTING TO THE
FREEZING DRIZZLE. AT THIS TIME FEEL THAT LOCATIONS NORTHEAST OF A
MCPHERSON TO EL DORADO TO CHANUTE LINE WILL HAVE THE BEST CHANCE TO
GET IN ON SOME OF THIS FREEZING DRIZZLE GENERALLY AFTER 10Z.
THEREFORE KCNU IS THE TAF SITE WITH THE BEST CHANCE TO SEE SOME OF
THIS EARLY FRI MORNING. BY AROUND 15-16Z CIGS WILL START TO CLIMB
ABOVE IFR LEVELS FOR LOCATIONS ALONG AND WEST OF I-135 WHILE KCNU
STAYS SOCKED-IN INTO THE AFTERNOON HOURS.
LAWSON
&&
.FIRE WEATHER...
ISSUED AT 341 AM CDT FRI MAR 22 2013
BELOW NORMAL TEMPERATURES THROUGH AT LEAST EARLY TO MID NEXT WEEK
ALONG WITH THE POTENTIAL FOR WIDESPREAD PRECIPITATION SATURDAY AND
SATURDAY NIGHT SHOULD CREATE RELATIVELY LOW FIRE DANGER OVER THE
NEXT SEVERAL DAYS.
ADK
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 51 34 37 28 / 10 40 60 80
HUTCHINSON 50 32 36 27 / 10 50 70 80
NEWTON 49 32 34 26 / 10 40 70 80
ELDORADO 48 33 37 28 / 20 30 60 80
WINFIELD-KWLD 51 35 40 29 / 10 30 60 80
RUSSELL 49 31 33 23 / 10 50 90 90
GREAT BEND 52 31 34 24 / 0 50 80 90
SALINA 48 31 35 27 / 20 40 80 90
MCPHERSON 49 32 34 26 / 10 40 80 90
COFFEYVILLE 47 35 44 31 / 20 20 60 80
CHANUTE 43 33 41 29 / 30 10 60 80
IOLA 42 32 41 28 / 30 10 60 80
PARSONS-KPPF 46 35 43 30 / 20 10 60 80
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY
AFTERNOON FOR KSZ032-033-047>053-067-068.
&&
$$
AREA FORECAST DISCUSSION
NWS WICHITA KS
1145 PM CDT THU MAR 21 2013
.UPDATE...
ISSUED AT 1015 PM CDT THU MAR 21 2013
UPDATED TO MAKE SOME MINOR TWEAKS TO GRIDS.
WATER VAPOR IMAGERY CONTINUES TO SHOW THE UPPER WAVE SLIDING OVER
WEST-CENTRAL KS. MEANWHILE EAST SURFACE WINDS CONTINUE TO ADVECT
HIGHER LOW LEVEL MOISTURE AND LOW CIGS ACROSS THE AREA. LOW LEVEL
ISENTROPIC LIFT IS RESULTING IN SOME DRIZZLE OVER NORTHEAST KS AND
WESTERN MISSOURI. WOULD EXPECTED THIS AREA OF DRIZZLE TO EVENTUALLY
EXPAND OVER SE PORTIONS OF THE FORECAST AREA. THE CHALLENGE TONIGHT
WILL BE KEEPING AN EYE ON SURFACE TEMPS FOR POSSIBLE FREEZING
DRIZZLE. THEY SHOULD HOVER VERY CLOSE TO OR JUST ABOVE FREEZING WITH
A POSSIBLE DECREASE AS SITES START TO WET BULB DOWN SLIGHTLY. THE
PRECIP OVER NW KS SHOULD ALSO IMPACT THE AREA AFTER 06Z AND MAY
BRING A MIX OF SOME SNOW OR LIGHT RAIN.
WHILE CONFIDENCE IS NOT HIGH ENOUGH AT THIS POINT TO RUN WITH AN
ADVISORY FOR FREEZING DRIZZLE...WOULD NOT BE SURPRISED TO SEE A
SMALL SHORT-LIVED ONE OUT FOR THE MORNING COMMUTE.
LAWSON
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 330 PM CDT THU MAR 21 2013
TONIGHT-FRI: LOTS OF DRY AIR IN THE LOWEST 2-3K FEET OF THE
ATMOSPHERE HAS LIMITED PRECIP REACHING THE GROUND TO THE EXTREME
ERN HALF OF THE FORECAST AREA. BUT MID LEVEL LIFT HAS BEEN SLOW TO
MOVE INTO THE AREA...WITH LOWER LAYER LIFT INCREASING INTO THE
EVENING HOURS ACROSS MAINLY ACROSS SRN/SERN KS. AS THIS LIFT
INCREASES...WILL SEE THE LOWER LAYERS SATURATE ENOUGH FOR AT LEAST
A DRIZZLE CHANCE ACROSS CENTRAL AND SRN KS. SFC TEMPS CLOSE TO
FREEZING ALONG OR NORTH OF HIGHWAY 50 MAY LEAD TO SOME VERY LIGHT
FREEZING DRIZZLE. FURTHER TO THE NORTH ALONG I-70 COULD SEE SOME
LIGHT RAIN OR SLEET MIX IN WITH THE FREEZING DRIZZLE AS WELL. SO
WILL CONTINUE THIS MENTION OVERNIGHT. NOT THINKING THIS WINTRY MIX
WILL LEAD TO ANY TRAVEL PROBLEMS AS WARM GROUND TEMPS WILL LEAD TO
FREEZING ONLY ON ELEVATED SURFACES.
AFTER THIS INITIAL LIFT MOVES EAST...LOW LEVEL MOISTURE WILL REMAIN
SOMEWHAT HIGH INTO FRI FOR SOME LOW CLOUDS. BUT FRI WILL BE THE
LULL BETWEEN THIS EVENINGS SYSTEM AND A MUCH MORE SIGNIFICANT SYSTEM
FOR SAT. SO ACTUALLY COULD SEE SOME BREAKS IN THE CLOUDS ON
FRI...WITH SUNSHINE ACTUALLY WARMING MAX TEMPS IN THE 50S FOR MOST
AREAS WEST OF INTERSTATE 135.
SAT-SUN: MODELS ARE COMING TOGETHER ON A MORE SIGNIFICANT STORM
SYSTEM EXPECTED TO MOVE OUT OF THE ROCKIES INTO THE PLAINS ON SAT.
THIS SYSTEM WILL START OUT WITH BETTER LOW LEVEL MOISTURE THAN
TODAYS SYSTEM...WITH WARM ADVECTION AND MOISTURE TRANSPORT AHEAD
OF THIS SHORTWAVE LEADING TO AN INCREASING CHANCE OF WIDESPREAD
SNOW OVER MOST OF CEN KS ON SAT. SATURATION/LIFT INCREASES IN THE
MAIN SNOW GROWTH REGION BY AROUND NOON SAT ACROSS CEN KS. SFC
TEMPS MAY START OUT JUST A LITTLE ABOVE FREEZING IN CEN
KS...BEFORE WET BULB EFFECTS DROP TEMPS ENOUGH FOR A HEAVY WET
SNOW TO BEGIN ACCUMULATING BY LATE SAT AFTN. THIS LIFT AND
SATURATION LASTS THE LONGEST OVER MOST OF CEN KS...FOR MODERATE
SNOW ACCUMULATIONS BY SAT EVE...WITH SOME AREAS IN CEN KS HAVING
THE POTENTIAL TO SEE 4 TO 7 INCHES OF ACCUMULATION. STRONG GUSTY
N-NW WINDS WILL ALSO BEGIN TO RAMP UP AS WELL FOR SAT
AFTN/EVE...SO WITH POSSIBLE TRAVEL IMPACTS ACROSS CEN KS...WILL
HOIST A WINTER STORM WATCH FOR CEN KS. A LITTLE MORE UNCERTAIN ON
HOW FAR SOUTH TO TAKE THIS WATCH...AS A MIX OF RAIN/SNOW WILL
CHANGEOVER TO ALL SNOW ACROSS SOUTH CEN KS AS WELL FOR SAT EVE.
THINK INITIAL SNOWFALL MAY MELT AS IT FALLS WHICH WILL CUT DOWN ON
SNOW TOTALS FOR AREAS NEAR KICT/EL DORADO AND NEWTON. COULD STILL
SEE ACCUMULATIONS AROUND 3 INCHES IN THIS AREA AS WELL...AS BEST
COMBINATION OF LIFT/SATURATION MOVES ACROSS SOUTH CEN KS BETWEEN
00-06Z/SUN. WOULD NOT BE SURPRISED TO SEE CEN KS UPGRADED TO A
WARNING WITH LATER SHIFTS WITH A POSSIBLE ADVISORY FOR AREAS
BETWEEN HIGHWAY 50 AND 54.
KETCHAM
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 327 PM CDT THU MAR 21 2013
AFTER THE WEEKEND SYSTEM MOVES OUT OF THE AREA...A BROAD TROUGH
LOOKS TO REMAIN OVER THE NORTHERN PLAIN FOR MON INTO TUE...WITH A
CANADIAN HIGH PRESSURE AREA SETTLING OVER THE AREA. THIS WILL LEAD
TO TEMPS REMAINING WELL BELOW NORMAL FOR THE START OF THE
WEEK...WITH BOTH THE GFS/ECMWF SHOWING 850H TEMPS OF MINUS 10. SO
EXPECT TEMPS TO STRUGGLE ACROSS THE AREA FOR MON/TUE...WITH TEMPS
EXPECTED TO BE 15 TO 20 DEGREES BELOW NORMAL. EXPECT A SLOW
WARMING TREND TOWARDS WED/THU WHICH WILL LEAD TO TEMPS CLOSER TO
CLIMO NORMS..WITH DRY CONDITIONS EXPECTED.
KETCHAM
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1145 PM CDT THU MAR 21 2013
AVIATION CONCERNS REMAIN LOW CIGS ALONG WITH SOME FREEZING DRIZZLE
POTENTIAL TONIGHT INTO FRI MORNING.
MVFR CIGS CONTINUE TO WORK WEST AND ARE JUST ABOUT READY TO GET
INTO KRSL. CURRENT THINKING IS THAT THESE CIGS WILL CONTINUE TO
LOWER OVERNIGHT WITH WIDESPREAD IFR CIGS LIKELY AFTER 08Z. THE
DRIZZLE THAT HAS OCCURRED SO FAR OVER NORTHEAST KS AND NW MO IS IN
AN AREA OF LOW LEVEL ISENTROPIC LIFT ALONG THE 285K SURFACE. IN FACT
THE LATEST RUC ANALYSIS IS SHOWING A COLD POCKET ALONG THIS SURFACE
RIGHT OVER FAR NORTHEAST KS WHICH IS LIKELY CONTRIBUTING TO THE
FREEZING DRIZZLE. AT THIS TIME FEEL THAT LOCATIONS NORTHEAST OF A
MCPHERSON TO EL DORADO TO CHANUTE LINE WILL HAVE THE BEST CHANCE TO
GET IN ON SOME OF THIS FREEZING DRIZZLE GENERALLY AFTER 10Z.
THEREFORE KCNU IS THE TAF SITE WITH THE BEST CHANCE TO SEE SOME OF
THIS EARLY FRI MORNING. BY AROUND 15-16Z CIGS WILL START TO CLIMB
ABOVE IFR LEVELS FOR LOCATIONS ALONG AND WEST OF I-135 WHILE KCNU
STAYS SOCKED-IN INTO THE AFTERNOON HOURS.
LAWSON
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 33 50 36 39 / 30 10 30 60
HUTCHINSON 31 52 34 36 / 30 10 30 70
NEWTON 29 48 34 35 / 30 10 30 60
ELDORADO 30 49 36 39 / 40 20 20 60
WINFIELD-KWLD 33 54 37 42 / 40 10 20 60
RUSSELL 29 51 31 33 / 30 10 50 80
GREAT BEND 31 54 33 34 / 30 10 50 80
SALINA 30 51 32 36 / 30 20 30 70
MCPHERSON 31 50 33 35 / 30 10 30 70
COFFEYVILLE 33 50 37 45 / 50 20 20 60
CHANUTE 30 48 35 41 / 50 20 20 60
IOLA 29 45 34 39 / 50 30 10 60
PARSONS-KPPF 31 48 37 44 / 50 20 20 60
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
AFTERNOON FOR KSZ032-033-047>051-067.
&&
$$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1139 PM CDT THU MAR 21 2013
.UPDATE...
ISSUED AT 1136 PM CDT THU MAR 21 2013
UPDATED AVIATION SECTION FOR 06Z TAF ISSUANCE.
UPDATE ISSUED AT 850 PM CDT THU MAR 21 2013
FORECAST APPEARS TO BE ON TRACK...WITH NO CHANGES MADE TO SNOWFALL
AMOUNTS OR ADVISORY AREAS. A BUFFER ZONE OF CHANCE POPS WAS EXPANDED
A COUPLE OF COUNTIES TO THE EAST FOR TONIGHT...MAINLY ALONG A KMDH
TO KPAH TO KHOP LINE. THIS WAS BASED MAINLY ON RUC MODEL DATA. THE
21Z RUC WAS MORE AGGRESSIVE THAN PREVIOUS RUNS IN BRINGING THE DEEP
MOISTURE /AS INDICATED BY 1000 TO 500 MB MEAN RH/ EASTWARD. RADAR
TRENDS SUPPORT THE RUC MODEL. WHATEVER PRECIP MAKES IT INTO THE AREA
OF CHANCE POPS WILL BE INSIGNIFICANT...SINCE THE MODELS DECREASE THE
DEEP MOISTURE FROM NORTHWEST TO SOUTHEAST LATE TONIGHT.
ALSO...SURFACE TEMPS WILL BE AT OR ABOVE FREEZING MUCH OF THE NIGHT
WHERE PRECIP OCCURS.
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 259 PM CDT THU MAR 21 2013
NO CHANGES PLANNED TO THE WINTER WEATHER ADVISORY.
THE 12Z MODELS ARE IN AGREEMENT WITH THE SYNOPTIC-SCALE
FEATURES/EVOLUTION THROUGH FRIDAY NIGHT. THE REGION WILL BE
SANDWICHED UNDER A WEAK UPPER RIDGE THAT SEPARATES A LARGE UPPER
LOW OVER QUEBEC FROM A DIGGING TROUGH OVER THE NORTHERN ROCKIES.
A COUPLE OF RELATIVELY WEAK MID-LEVEL DISTURBANCES WILL TRY TO
PUSH THROUGH THE SKINNY RIDGE AND ACROSS OUR AREA TONIGHT AND
FRIDAY. AS THE WESTERN TROUGH DIGS INTO THE CENTRAL ROCKIES...THE
MID/UPPER RIDGE ASSERTS ITSELF OVER OUR REGION FRIDAY NIGHT.
ALTHOUGH THE NAM AND GFS EACH PRODUCE PLENTY OF CLOUD COVER
TONIGHT AND INTO FRIDAY MORNING OVER THE SOUTHWEST THIRD OF THE
AREA...SIGNIFICANT FOCUSED LIFT IS HARDER TO COME BY. THE TWO
MODELS ARE IN AGREEMENT IN SOME FOCUSED LIFT AROUND 00Z OVER
RIPLEY COUNTY. THE LIFT IS MAXIMIZED IN THE DENDRITIC GROWTH ZONE
WHICH COULD LEAD TO QUITE AN INITIAL BURST OF ACCUMULATING SNOW.
THE PROBLEM IS THAT THE LIFT DOES NOT LAST LONG AT ALL...AND
FOCUSED/SIGNIFICANT LIFT IS HARD TO FIND LATE THIS EVENING AND
OVERNIGHT. WOULD NOT BE BE SURPRISED IF THE ADVISORY IS CANCELLED
EARLY. ON TOP OF THE LIFT ISSUE...THE SNOW WILL HAVE TO OVERCOME
A VERY COLD...DRY AIRMASS FOR LATE MARCH. THIS WILL LIKELY RESULT
IN A VERY SHARP NORTHEAST EDGE TO THE ACCUMULATING SNOW. WILL
LEAVE THE ADVISORY AREA ALONE DUE TO COUNTY GEOMETRY ISSUES...BUT
NORTHEASTERN PORTIONS OF STODDARD AND NEW MADRID AND MAYBE EVEN
WAYNE COUNTY MAY STRUGGLE TO GET AN INCH OF SNOW TONIGHT.
USED HPC QPF AND A 10 TO 1 SNOW TO LIQUID RATIO TO GET VERY SIMILAR
STORM TOTAL SNOW ACCUMULATIONS AS PREVIOUSLY FORECAST. 4 INCHES
WILL BE A REAL POSSIBILITY IN SOUTHWEST PORTIONS OF RIPLEY COUNTY
WITH A SHARP GRADIENT DOWN TO AN INCH FROM GREENVILLE TO DEXTER TO
NEW MADRID.
MODEL SOUNDINGS INDICATE THAT THE COLUMN WILL APPROACH THE
FREEZING LINE IN THE FAR SOUTHWEST LATE THIS EVENING...WHICH WOULD
LEAD TO SOME SLEET POTENTIAL. THIS COULD POTENTIALLY LEAD TO
LOWER ACCUMULATIONS. THE MODELS ARE IN AGREEMENT IN WARMING THE
COLUMN QUICKLY FRIDAY MORNING...SO ANY PRECIPITATION THAT IS LEFT
WILL TRANSITION TO RAIN BY MIDDAY. ANY PRECIPITATION WILL BE FOCUSED
ON THE SOUTHERN BORDER OF THE AREA FRIDAY...BUT WOULD BE SURPRISED
TO SEE MUCH AT ALL. FRIDAY NIGHT SHOULD BE DRY...BUT LEFT A 20-30
POP OVER THE SOUTHERN HALF OF THE AREA JUST TO FIT IN.
IT SHOULD BE QUITE COLD IN THE NORTHEAST TONIGHT...GUIDANCE SEEMS
TO HAVE THIS IN HAND. UNDERCUT GUIDANCE FOR HIGHS FRIDAY IN MOST
LOCATIONS WITH PLENTY OF CLOUDS AND AN EAST WIND EXPECTED. KNOCKED
LOWS FRIDAY NIGHT DOWN QUITE A BIT WITH GOOD RADIATIONAL COOLING
EXPECTED. GUIDANCE HAS A GOOD IDEA FOR FRIDAY NIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 259 PM CDT THU MAR 21 2013
THE GENERAL WEATHER SCENARIO FOR THE WEEKEND AND INTO EARLY NEXT
WEEK HAS STABILIZED SOMEWHAT WITH RESPECT TO THE PROMINENT FEATURES
IMPACTING THE WFO PAH FORECAST AREA.
THE MANDATORY LEVEL TEMPERATURES FROM SURFACE TO 700 MB FOR THE 00Z
AND 12Z THURSDAY NUMERICAL MODEL SUITES INITIALIZED ONE HALF TO
ALMOST TWO DEGREES TOO WARM UPSTREAM AND OVER THE WFO PAH FORECAST
AREA. THE LEAST IMPACTED GUIDANCE HAS BEEN THE DETERMINISTIC NAM-WRF
SUITE...FOLLOWED BY THE SREF/GFS GUIDANCE...THE ECMWF AND CANADIAN
GUIDANCE...FOLLOWED BY THE GFS ENSEMBLE /WHICH IRONICALLY WAS ONE OF
THE BETTER PERFORMING MODELS ON WEDNESDAY/.
WITH RESPECT TO A POP/WEATHER/WEATHER TYPE SOLUTION FOR THE EXTENDED
FORECAST PERIOD...THIS MEANS ESSENTIAL TRACK OF THE NORTH-SOUTH
ORIENTED TROUGH IN THE LEE OF THE CENTRAL ROCKIES WILL DIG INTO A
SURFACE LOW SLIGHTLY FURTHER SOUTH. THE MAIN TRACK OF THE SURFACE
LOW WILL LIKELY BE JUST SOUTH OF THE WFO PAH FORECAST
AREA...POSSIBLY NUDGING INTO SOUTHEAST SECTIONS OF THE PENNYRILE
REGION OF WEST KENTUCKY...NEAR /KHOP/ FORT CAMPBELL KY. BOTH THE
UPPER LOW AND SURFACE LOW WILL MOVE IN CONCERT AND DEEPEN RAPIDLY
/BECOME MORE VERTICALLY STACKED OVER THE SOUTHERN HALF OF THE WFO
PAH FORECAST AREA GENERALLY BETWEEN /10 PM CDT/ SATURDAY NIGHT TO /7
AM CDT/ SUNDAY MORNING.
THE BIG QUESTIONS FOR SATURDAY NIGHT INTO SUNDAY MORNING WILL BE
MULTI-FOLD. THE FIRST QUESTION IS TO WHAT DEGREE OF THE VERTICAL
MOMENTUM /UPWARD MOTION/ WILL BE TRANSLATED INTO HORIZONTAL FORCING
ON THE NORTHERN/SOUTHERN ENDS OF THE WFO PAH FORECAST AREA...MAINLY
IN SURFACE WIND AND TEMPERATURE FIELDS FOR SHARPENING GRADIENTS.
MOST OF THE MODEL GUIDANCE IS SUGGESTING THAT A GOOD PORTION OF THE
ENERGY WILL BE EXPENDED VERTICALLY. THIS NOTION CONTINUES TO SUPPORT
A MENTION OF THUNDERSTORMS ALONG THE SOUTHERN COUNTIES OF THE WFO
PAH FORECAST AREA...WHERE LAPSE RATES/VORTICITY/FORCING WILL SUPPORT
UPRIGHT CONVECTION ALONG AND JUST NORTH OF THE SURFACE LOW. THE
SECOND QUESTION WILL BE WHETHER THE TRANSIENT DEFORMATION ZONE ALONG
ROUTE 60 IN SOUTHEAST MO...ROUTE 13 IN SOUTHERN IL AND THE OHIO
RIVER IN SOUTHWEST IN/NORTHWEST KY...WILL CAUSE A SIGNIFICANT PHASE
CHANGE IN PRECIPITATION TYPE. IT IS CONCEIVABLE THAT THERE MAY BE A
1 TO 3 HOUR PERIOD OVERNIGHT IN THE AFOREMENTIONED AREA WHERE
MID-LEVEL FORCING MAY GENERATE UPRIGHT CONVECTION /THUNDERSTORMS/
AND MIXED PRECIPITATION /SLEET...HAIL...SNOW...RAIN/ NEAR THE
DEFORMATION ZONE. ALSO...GIVEN THE DEMARCATION LINE BETWEEN
MEASURABLE SNOW ALONG THE NORTHERN EDGE OF THE WFO PAH FORECAST
AREA...WOULD PREFER TO SEE THE OUTPUT FROM THE 4KM NAM-WRF GUIDANCE
ON FRIDAY BEFORE PINPOINT PRECIPITATION TYPE...INTENSITY AND THE
OCCURRENCE OF THUNDERSTORMS ALONG THE NORTH END OF THE WFO PAH
FORECAST AREA. THE STORM PREDICTION CENTER HAS ALREADY HINTED IN
THEIR DAY THREE OUTLOOK A CHANCE FOR GENERAL THUNDER ACROSS MOST OF
THE WFO PAH FORECAST AREA. PLAN TO ADD A CONDITIONAL MENTION OF
THUNDER ACROSS THE NORTHERN EDGE OF THE WFO PAH FORECAST AREA FOR
PLANNING PURPOSES...ALTHOUGH THERE WILL BE NO MENTION OF
THUNDERSTORMS IN THE NORTH WITH THIS FORECAST PACKAGE.
FOLLOWING THE PASSAGE OF THE SURFACE/UPPER LOW SATURDAY NIGHT INTO
SUNDAY...THE NUMERICAL MODELS HAVE SPED UP THE DEPARTURE OF
MEASURABLE POPS/WEATHER FROM SOUTHWEST TO NORTHEAST BY AS MUCH AS
SIX HOURS OR MORE. THIS SHOULD DRY THINGS OUT ACROSS THE WFO PAH
FORECAST AREA FROM TUESDAY THROUGH WEDNESDAY. ANOTHER...WEAKER
IMPULSE IS FORECAST TO MOVE THROUGH ON THURSDAY...BUT SHOULD
CONTRIBUTE LITTLE TO ANY MEASURABLE PRECIPITATION.
AS MENTIONED NEAR THE TOP OF THE EXTENDED FORECAST
DISCUSSION...TEMPERATURES WERE TOO WARM. ADJUSTMENTS WERE MADE TO
KEEP TEMPERATURES SOME 15 TO 25 DEGREES BELOW NORMAL AS THE FLOW
AROUND THE SEMI-PERMANENT EASTERN U.S. CYCLONIC VORTEX KEEPS
THICKNESSES LOWER AND SUSTAIN COLD AIR ADVECTION ACROSS THE WFO PAH
FORECAST AREA. WOULD NOT BE SURPRISED TO SEE MULTIPLE DAYS OF COLD
AIR STRATOCUMULUS OR STRATUS...ESPECIALLY ALONG THE NORTHERN 1/2 OF
THE WFO PAH FORECAST AREA. A FEW FLURRIES OR SPRINKLES MAY BE
LIKELY...BUT DO NOT PLAN TO MENTION THESE TRACE EVENTS SO FAR OUT IN
THE FORECAST PACKAGE BASED ON POTENTIAL COVERAGE.
THERE MAY BE SOME LIGHT AT THE END OF THE COLD TEMPERATURE
TUNNEL...AS THE 240 HOUR GUIDANCE SHOWS A STRONG RIDGE NOSING INTO
WESTERN MO...IT MAY TAKE UNTIL THE FIRST WEEK OF APRIL BEFORE WE SEE
ANY MEASURABLE WARMING AT OR ABOVE NORMAL /LOW TO MID 60S/ THIS TIME
OF YEAR.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 259 PM CDT THU MAR 21 2013
NO CHANGES PLANNED TO THE WINTER WEATHER ADVISORY.
THE 12Z MODELS ARE IN AGREEMENT WITH THE SYNOPTIC-SCALE
FEATURES/EVOLUTION THROUGH FRIDAY NIGHT. THE REGION WILL BE
SANDWICHED UNDER A WEAK UPPER RIDGE THAT SEPARATES A LARGE UPPER
LOW OVER QUEBEC FROM A DIGGING TROUGH OVER THE NORTHERN ROCKIES.
A COUPLE OF RELATIVELY WEAK MID-LEVEL DISTURBANCES WILL TRY TO
PUSH THROUGH THE SKINNY RIDGE AND ACROSS OUR AREA TONIGHT AND
FRIDAY. AS THE WESTERN TROUGH DIGS INTO THE CENTRAL ROCKIES...THE
MID/UPPER RIDGE ASSERTS ITSELF OVER OUR REGION FRIDAY NIGHT.
ALTHOUGH THE NAM AND GFS EACH PRODUCE PLENTY OF CLOUD COVER
TONIGHT AND INTO FRIDAY MORNING OVER THE SOUTHWEST THIRD OF THE
AREA...SIGNIFICANT FOCUSED LIFT IS HARDER TO COME BY. THE TWO
MODELS ARE IN AGREEMENT IN SOME FOCUSED LIFT AROUND 00Z OVER
RIPLEY COUNTY. THE LIFT IS MAXIMIZED IN THE DENDRITIC GROWTH ZONE
WHICH COULD LEAD TO QUITE AN INITIAL BURST OF ACCUMULATING SNOW.
THE PROBLEM IS THAT THE LIFT DOES NOT LAST LONG AT ALL...AND
FOCUSED/SIGNIFICANT LIFT IS HARD TO FIND LATE THIS EVENING AND
OVERNIGHT. WOULD NOT BE BE SURPRISED IF THE ADVISORY IS CANCELLED
EARLY. ON TOP OF THE LIFT ISSUE...THE SNOW WILL HAVE TO OVERCOME
A VERY COLD...DRY AIRMASS FOR LATE MARCH. THIS WILL LIKELY RESULT
IN A VERY SHARP NORTHEAST EDGE TO THE ACCUMULATING SNOW. WILL
LEAVE THE ADVISORY AREA ALONE DUE TO COUNTY GEOMETRY ISSUES...BUT
NORTHEASTERN PORTIONS OF STODDARD AND NEW MADRID AND MAYBE EVEN
WAYNE COUNTY MAY STRUGGLE TO GET AN INCH OF SNOW TONIGHT.
USED HPC QPF AND A 10 TO 1 SNOW TO LIQUID RATIO TO GET VERY SIMILAR
STORM TOTAL SNOW ACCUMULATIONS AS PREVIOUSLY FORECAST. 4 INCHES
WILL BE A REAL POSSIBILITY IN SOUTHWEST PORTIONS OF RIPLEY COUNTY
WITH A SHARP GRADIENT DOWN TO AN INCH FROM GREENVILLE TO DEXTER TO
NEW MADRID.
MODEL SOUNDINGS INDICATE THAT THE COLUMN WILL APPROACH THE
FREEZING LINE IN THE FAR SOUTHWEST LATE THIS EVENING...WHICH WOULD
LEAD TO SOME SLEET POTENTIAL. THIS COULD POTENTIALLY LEAD TO
LOWER ACCUMULATIONS. THE MODELS ARE IN AGREEMENT IN WARMING THE
COLUMN QUICKLY FRIDAY MORNING...SO ANY PRECIPITATION THAT IS LEFT
WILL TRANSITION TO RAIN BY MIDDAY. ANY PRECIPITATION WILL BE FOCUSED
ON THE SOUTHERN BORDER OF THE AREA FRIDAY...BUT WOULD BE SURPRISED
TO SEE MUCH AT ALL. FRIDAY NIGHT SHOULD BE DRY...BUT LEFT A 20-30
POP OVER THE SOUTHERN HALF OF THE AREA JUST TO FIT IN.
IT SHOULD BE QUITE COLD IN THE NORTHEAST TONIGHT...GUIDANCE SEEMS
TO HAVE THIS IN HAND. UNDERCUT GUIDANCE FOR HIGHS FRIDAY IN MOST
LOCATIONS WITH PLENTY OF CLOUDS AND AN EAST WIND EXPECTED. KNOCKED
LOWS FRIDAY NIGHT DOWN QUITE A BIT WITH GOOD RADIATIONAL COOLING
EXPECTED. GUIDANCE HAS A GOOD IDEA FOR FRIDAY NIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 259 PM CDT THU MAR 21 2013
THE GENERAL WEATHER SCENARIO FOR THE WEEKEND AND INTO EARLY NEXT
WEEK HAS STABILIZED SOMEWHAT WITH RESPECT TO THE PROMINENT FEATURES
IMPACTING THE WFO PAH FORECAST AREA.
THE MANDATORY LEVEL TEMPERATURES FROM SURFACE TO 700 MB FOR THE 00Z
AND 12Z THURSDAY NUMERICAL MODEL SUITES INITIALIZED ONE HALF TO
ALMOST TWO DEGREES TOO WARM UPSTREAM AND OVER THE WFO PAH FORECAST
AREA. THE LEAST IMPACTED GUIDANCE HAS BEEN THE DETERMINISTIC NAM-WRF
SUITE...FOLLOWED BY THE SREF/GFS GUIDANCE...THE ECMWF AND CANADIAN
GUIDANCE...FOLLOWED BY THE GFS ENSEMBLE /WHICH IRONICALLY WAS ONE OF
THE BETTER PERFORMING MODELS ON WEDNESDAY/.
WITH RESPECT TO A POP/WEATHER/WEATHER TYPE SOLUTION FOR THE EXTENDED
FORECAST PERIOD...THIS MEANS ESSENTIAL TRACK OF THE NORTH-SOUTH
ORIENTED TROUGH IN THE LEE OF THE CENTRAL ROCKIES WILL DIG INTO A
SURFACE LOW SLIGHTLY FURTHER SOUTH. THE MAIN TRACK OF THE SURFACE
LOW WILL LIKELY BE JUST SOUTH OF THE WFO PAH FORECAST
AREA...POSSIBLY NUDGING INTO SOUTHEAST SECTIONS OF THE PENNYRILE
REGION OF WEST KENTUCKY...NEAR /KHOP/ FORT CAMPBELL KY. BOTH THE
UPPER LOW AND SURFACE LOW WILL MOVE IN CONCERT AND DEEPEN RAPIDLY
/BECOME MORE VERTICALLY STACKED OVER THE SOUTHERN HALF OF THE WFO
PAH FORECAST AREA GENERALLY BETWEEN /10 PM CDT/ SATURDAY NIGHT TO /7
AM CDT/ SUNDAY MORNING.
THE BIG QUESTIONS FOR SATURDAY NIGHT INTO SUNDAY MORNING WILL BE
MULTI-FOLD. THE FIRST QUESTION IS TO WHAT DEGREE OF THE VERTICAL
MOMENTUM /UPWARD MOTION/ WILL BE TRANSLATED INTO HORIZONTAL FORCING
ON THE NORTHERN/SOUTHERN ENDS OF THE WFO PAH FORECAST AREA...MAINLY
IN SURFACE WIND AND TEMPERATURE FIELDS FOR SHARPENING GRADIENTS.
MOST OF THE MODEL GUIDANCE IS SUGGESTING THAT A GOOD PORTION OF THE
ENERGY WILL BE EXPENDED VERTICALLY. THIS NOTION CONTINUES TO SUPPORT
A MENTION OF THUNDERSTORMS ALONG THE SOUTHERN COUNTIES OF THE WFO
PAH FORECAST AREA...WHERE LAPSE RATES/VORTICITY/FORCING WILL SUPPORT
UPRIGHT CONVECTION ALONG AND JUST NORTH OF THE SURFACE LOW. THE
SECOND QUESTION WILL BE WHETHER THE TRANSIENT DEFORMATION ZONE ALONG
ROUTE 60 IN SOUTHEAST MO...ROUTE 13 IN SOUTHERN IL AND THE OHIO
RIVER IN SOUTHWEST IN/NORTHWEST KY...WILL CAUSE A SIGNIFICANT PHASE
CHANGE IN PRECIPITATION TYPE. IT IS CONCEIVABLE THAT THERE MAY BE A
1 TO 3 HOUR PERIOD OVERNIGHT IN THE AFOREMENTIONED AREA WHERE
MID-LEVEL FORCING MAY GENERATE UPRIGHT CONVECTION /THUNDERSTORMS/
AND MIXED PRECIPITATION /SLEET...HAIL...SNOW...RAIN/ NEAR THE
DEFORMATION ZONE. ALSO...GIVEN THE DEMARCATION LINE BETWEEN
MEASURABLE SNOW ALONG THE NORTHERN EDGE OF THE WFO PAH FORECAST
AREA...WOULD PREFER TO SEE THE OUTPUT FROM THE 4KM NAM-WRF GUIDANCE
ON FRIDAY BEFORE PINPOINT PRECIPITATION TYPE...INTENSITY AND THE
OCCURRENCE OF THUNDERSTORMS ALONG THE NORTH END OF THE WFO PAH
FORECAST AREA. THE STORM PREDICTION CENTER HAS ALREADY HINTED IN
THEIR DAY THREE OUTLOOK A CHANCE FOR GENERAL THUNDER ACROSS MOST OF
THE WFO PAH FORECAST AREA. PLAN TO ADD A CONDITIONAL MENTION OF
THUNDER ACROSS THE NORTHERN EDGE OF THE WFO PAH FORECAST AREA FOR
PLANNING PURPOSES...ALTHOUGH THERE WILL BE NO MENTION OF
THUNDERSTORMS IN THE NORTH WITH THIS FORECAST PACKAGE.
FOLLOWING THE PASSAGE OF THE SURFACE/UPPER LOW SATURDAY NIGHT INTO
SUNDAY...THE NUMERICAL MODELS HAVE SPED UP THE DEPARTURE OF
MEASURABLE POPS/WEATHER FROM SOUTHWEST TO NORTHEAST BY AS MUCH AS
SIX HOURS OR MORE. THIS SHOULD DRY THINGS OUT ACROSS THE WFO PAH
FORECAST AREA FROM TUESDAY THROUGH WEDNESDAY. ANOTHER...WEAKER
IMPULSE IS FORECAST TO MOVE THROUGH ON THURSDAY...BUT SHOULD
CONTRIBUTE LITTLE TO ANY MEASURABLE PRECIPITATION.
AS MENTIONED NEAR THE TOP OF THE EXTENDED FORECAST
DISCUSSION...TEMPERATURES WERE TOO WARM. ADJUSTMENTS WERE MADE TO
KEEP TEMPERATURES SOME 15 TO 25 DEGREES BELOW NORMAL AS THE FLOW
AROUND THE SEMI-PERMANENT EASTERN U.S. CYCLONIC VORTEX KEEPS
THICKNESSES LOWER AND SUSTAIN COLD AIR ADVECTION ACROSS THE WFO PAH
FORECAST AREA. WOULD NOT BE SURPRISED TO SEE MULTIPLE DAYS OF COLD
AIR STRATOCUMULUS OR STRATUS...ESPECIALLY ALONG THE NORTHERN 1/2 OF
THE WFO PAH FORECAST AREA. A FEW FLURRIES OR SPRINKLES MAY BE
LIKELY...BUT DO NOT PLAN TO MENTION THESE TRACE EVENTS SO FAR OUT IN
THE FORECAST PACKAGE BASED ON POTENTIAL COVERAGE.
THERE MAY BE SOME LIGHT AT THE END OF THE COLD TEMPERATURE
TUNNEL...AS THE 240 HOUR GUIDANCE SHOWS A STRONG RIDGE NOSING INTO
WESTERN MO...IT MAY TAKE UNTIL THE FIRST WEEK OF APRIL BEFORE WE SEE
ANY MEASURABLE WARMING AT OR ABOVE NORMAL /LOW TO MID 60S/ THIS TIME
OF YEAR.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1136 PM CDT THU MAR 21 2013
RADAR SHOWS SNOW SOUTH/WEST OF KCGI AND MODELS...FOR THE MOST
PART...KEEP IT THERE. LOW VFR CIGS SHOULD SEE A SCATTERED MVFR
DECK BECOME PREVAILING OVERNIGHT/TOWARD MORNING. THIS WILL
TRANSLATE TO PADUCAH AS WELL...AND THEN FURTHER EAST TO KEVV/KOWB
BY THE PLANNING PERIOD. TOWARD THE END OF THE EFFECTIVE VALID
TIME...SOME LIGHT PCPN MAY DEVELOP KCGI/KPAH.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...WINTER WEATHER ADVISORY UNTIL 7 AM CDT FRIDAY FOR MOZ100-107>110-
114.
IN...NONE.
KY...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
859 PM EDT SAT MAR 23 2013
.UPDATE...
ISSUED AT 858 PM EDT SAT MAR 23 2013
NO MAJOR CHANGES TO THE GOING FORECAST. OVERNIGHT SHIFT WILL NEED TO
WATCH FOR HEAVIER FREEZING DRIZZLE IN THE UPSLOPE AREAS OF NORTH
CENTRAL UPPER MICHIGAN. THE 18Z NAM AND 21Z RAP BOTH SUGGEST A
PERIOD OF MODERATE UPWARD MOTION AS THE UPSLOPE FLOW INCREASES WHEN
THE PBL WINDS BECOME N-NE. BOTH OF THESE MODELS SHOW A SATURATED
LAYER BETWEEN -6 AND -12C WHICH WOULD INDICATE THAT MOSTLY
SUPERCOOLED WATER WITH VERY LITTLE ICE NUCLEATION. IN FACT...THIS IS
WHAT HAS BEEN SEEN AT THE OFFICE THIS EVENING AND HAS ALLOWED FOR A
GLAZE ON ELEVATED SURFACES. HAVE OPTED TO ISSUE TO SPECIAL WEATHER
STATEMENT TO ACCOUNT FOR POTENTIAL SLIPPERY ROADS OVERNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 353 PM EDT SAT MAR 23 2013
DON/T EXPECT THE WEATHER TO BE MUCH DIFFERENT THAN THE LAST DAY OR
TWO. THIS OVERALL QUIET PATTERN IS DUE TO THE STRONG NEGATIVE NAO
BLOCKING PATTERN PUSHING THE JET STREAM FARTHER SOUTH AND KEEPING
THE STORM TRACK WELL TO THE SOUTH OF THE AREA. THE MAIN SYSTEM TO
BE AFFECTING LOCATIONS WELL TO THE SOUTH OF OUR CWA WILL MOVE FROM
CENTRAL PLAINS THIS AFTERNOON TO THE OHIO RIVER VALLEY ON SUNDAY.
WHILE THIS SYSTEM TRACKS TO THE SOUTH...NORTHEASTERLY FLOW ALOFT
WILL KEEP THE COLDER 850MB TEMPS...AROUND -11C OR 4-6
DEGREES BELOW NORMAL...OVER THE AREA DURING THE SHORT TERM PERIOD.
THE MOISTURE OVER THE AREA IS FAIRLY SHALLOW...AROUND
975-900MB...FOR TONIGHT AND SUNDAY MORNING BEFORE A POCKET OF DRIER
AIR ARRIVES ON SUNDAY AFTERNOON FROM THE NORTHEAST. SKIES MAY
SCATTER OUT A LITTLE BIT BASED OFF SOME OF THE GAPS OVER
LAKE SUPERIOR AND WITH THE LOSS OF DIURNAL HEATING...BUT WITH
CLOUDS MAKING THEIR WAY SOUTH OVER THE NORTHERN LAKE AND MODELS
SHOWING DECENT MOISTURE PRESENT...WOULD EXPECT CLOUDS TO QUICKLY
FILL BACK IN TONIGHT. THUS...EXPECT MOSTLY CLOUDY CONDITIONS TO
AFFECT THE AREA TONIGHT INTO SUNDAY MORNING...BUT AS THE DRIER AIR
WORKS IN FROM THE NORTHEAST ON SUNDAY...A DECREASING CLOUD TREND IS
EXPECTED THROUGH THE LATER AFTERNOON HOURS OVER THE NORTHEAST
HALF OF THE CWA.
AS FOR PRECIPITATION...WOULD EXPECT IT TO BE SIMILAR TO THE LAST TWO
DAYS WHERE IT PEAKS UP DURING THE OVERNIGHT HOURS DUE TO REDUCED
MIXING. THIS IS ESPECIALLY TRUE IN THE NORTHEAST WIND FAVORED
LOCATIONS DUE TO WINDS VEERING FROM A MORE VARIABLE NORTHERLY
DIRECTION LATE THIS AFTERNOON TO A PERSISTENT NORTHEAST DIRECTION
TONIGHT WITH THE WEAKENING HIGH PRESSURE RIDGE AND LOW EXITING THE
CENTRAL PLAINS. BUMPED UP POPS TO CHANCES OVER THE HIGHER TERRAIN OF
THE NORTH CENTRAL LATE TONIGHT BASED ON ALL OF THE HIGHER RESOLUTION
MODELS PICKING UP ON THE UPSLOPE FORCING AND INCREASED 950-925MB
OMEGA. WITH THE DRIER AIR LIKELY ARRIVING ON LATE
SUNDAY MORNING...WOULD EXPECT IT TO COME TO AN END FAIRLY QUICKLY ON
SUNDAY AFTERNOON. SINCE CLOUD IS STILL LOCATED IN THE BORDERLINE
ICE CRYSTAL REGION...WILL CONTINUE TO MENTION FREEZING DRIZZLE
ALONG WITH THE SNOW TONIGHT INTO SUNDAY MORNING. FINALLY...DID ADD A
FEW FLURRIES OVER THE INTERIOR WEST DUE TO DIURNAL HEATING
INCREASING THE LOW LEVEL LAPSE RATES AND POTENTIALLY LEADING TO SOME
LIGHT FLURRIES TOWARDS THE AFTERNOON WITH THE LINGER MOISTURE.
LOWS TONIGHT WILL DEPEND ON CLOUD COVER AND THINK THE COOLEST
LOCATIONS WILL BE OVER THE EASTERN CWA. LAST NIGHT...WHERE IT
CLEARED OUT OVER THE EAST...LOCATIONS FELL INTO THE SINGLE DIGITS
ABOVE ZERO. HAVE FOLLOWED THAT IDEA FOR SPINCICH LAKE...BUT BANKED
ON MORE CLOUDS OVER THE REST OF THE AREA AND WENT WITH UPPER TEENS
OR LOWER 20S. HIGHS ON SUNDAY SHOULDN/T BE MUCH DIFFERENT THAN
TODAY AND WILL CONTINUE TO MENTION LOW TO MID 30S.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 353 PM EDT SAT MAR 23 2013
SUN NIGHT AND MON...AS A MID-LEVEL AND SFC LOW MOVES THROUGH THE
OHIO VALLEY REACHING THE MID-ATLANTIC COAST MONDAY
AFTERNOON...MODELS SUGGEST INCREASING 850-700 MB MOISTURE WILL BE
DRAWN TOWARD UPPER MICHIGAN FROM THE NORTHEAST. THE INCREASED
MOISTURE COMBINED WITH NNE FLOW AND 850 MB TEMPS REMAINING IN THE
-10C TO -11C RANGE WILL BE ENOUGH TO SUPPORT AT LEAST SCT SNOW
SHOWERS INTO THE WEST AND N CNTRL PORTIONS OF THE CWA. ANY LOCAL
SNOWFALL ACCUMULATIONS FM THESE SHOWERS SHOULD REMAIN LIGHT...AROUND
A HALF INCH OR LESS PER 12 HRS.
TUE...MOISTURE TO NEAR 800 MB IN THE MORNING AND 850 MB TEMPS
LINGERING IN THE -10 TO -12C RANGE...SHOULD STILL RESULT IN
SCT/ISOLD -SHSN WEST AND N CNTRL COUNTIES IN THE MORNING WITH NRLY
FLOW. EXPECT THE PCPN TO DIMINISH DURING THE AFTERNOON ESPECIALLY
NCNTRL WHERE SIGNIFICANT 850-700 MB DRYING IS EXPECTED...PER
GFS/ECMWF MOISTURE FCST.
WED AND THU...WITH WEAK MID LEVEL AND SFC RIDGING EXPECTED AND
DRYING/SUBSIDENCE NOTED ON MODEL SNDGS...LOOK FOR DRY CONDITIONS
WITH GREATER SUNSHINE AS HIGH TEMPS SLOWLY MODERATE INTO THE MID TO
UPPER 30S BY THU.
FRI AND SAT...THE 12Z GFS...ECMWF AND GEM-NH HAVE ALL TRENDED
FARTHER SOUTH WITH COMPACT MID LEVEL LOW APPROACHING FM SOUTH
CENTRAL CANADA AND MOVING ACROSS THE NRN PORTION OF LAKE SUPERIOR
FRI AFTERNOON INTO SATURDAY. GIVEN THE WEAK TO MODERATE Q-VECT CONV
SPREADING INTO THE AREA ALONG THE ASSOCIATED COLD FRONT HAVE DECIDED
TO INTRODUCE SLIGHT CHC POPS FOR FRIDAY INTO SATURDAY. WEAK CAA
BEHIND THE FRONT COULD ALSO CONTRIBUTE TO LIGHT SCT LAKE EFFECT SNOW
SHOWERS FRIDAY NIGHT INTO SATURDAY ACROSS THE NRN TIER AND ERN
COUNTIES IN NW FLOW. ONLY SLIGHT CHC POPS WARRANTED AT THIS TIME AS
THIS IS THE FIRST MODEL RUN TO SHOW THE FARTHER SOUTH TRACK WITH
CANADIAN MID-LVL LOW. IF MODELS CONTINUE TO TREND FARTHER SOUTH WITH
THIS SYSTEM...THEN POPS EVENTUALLY WILL NEED TO INCREASED FOR LATE
NEXT WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 859 PM EDT SAT MAR 23 2013
MVFR CONDITIONS SHOULD PERSIST THROUGH THE NIGHT AND INTO SUNDAY
ACROSS THE AREA. WILL NEED TO WATCH FOR MARGINAL IFR CONDITIONS
DEVELOPING AT SAW DUE TO INCREASED UPSLOPE NORTHERLY FLOW AND
SUFFICIENT LOW LEVEL MOISTURE. IN ADDITION...ALL SITES WILL LIKELY
SEE SOME FREEZING DRIZZLE DEVELOPMENT OVERNIGHT...ALTHOUGH THE
HEAVIEST WILL BE AT SAW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 353 PM EDT SAT MAR 23 2013
A HIGH PRESSURE OVER CENTRAL CANADA WILL KEEP A RIDGE OVER THE
UPPER GREAT LAKES REGION INTO SUNDAY MONRING. BUT AS A LOW PRESSURE
SYSTEM DEPARTS THE CENTRAL PLAINS AND MOVES THROUGH THE OHIO RIVER
VALLEY THROUGH MONDAY NIGHT...THE RIDGE WILL WEAKEN AND SHIFT WEST.
THIS WILL LEAD TO PERSISTENT NORTHERLY FLOW ACROSS THE
AREA...ALTHOUGH THE WINDS SHOULD BE LESS THAN 25 KNOTS. AS THE
LOW SHIFTS OFF THE ATLANTIC SEABOARD ON TUESDAY...HIGH PRESSURE
WILL BEGIN TO SHIFT BACK TO THE EAST AND COVER THE UPPER GREAT
LAKES FROM TUESDAY NIGHT THROUGH THE REST OF THE WORK WEEK. THIS
WILL KEEP THE NORTHERLY WINDS BELOW 15KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...MRD
SHORT TERM...SRF
LONG TERM...VOSS
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
144 PM EDT FRI MAR 22 2013
.UPDATE...
ISSUED AT 1040 AM EDT FRI MAR 22 2013
SOME SLIGHTLY DEEPER MOISTURE HAS MOVED INTO THE AREA...JUST ENOUGH
TO ALLOW SOME SNOW TO MIX IN WITH THE FREEZING DRIZZLE DUE TO THE
TOP OF THE CLOUD BEING AROUND -12C. HOWEVER...THIS IS EXPECTED TO
ONLY LAST A FEW HOURS PER THE RAP SOUNDINGS. OTHERWISE...HAVE OPTED
TO KEEP FREEZING DRIZZLE AROUND FOR MUCH OF THE DAY CLOSER TO LAKE
SUPERIOR DUE TO THE PERSISTENT UPSLOPE FLOW THROUGH THE DAY AND
SHALLOW MOISTURE. ANY SURFACES THAT ARE UNTREATED MAY BE SLIPPERY AT
TIMES.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 505 AM EDT FRI MAR 22 2013
UPR LEVEL TROUGH DRIFTS FARTHER EAST OF UPR LAKES WITH RIDGING
POISED TO MOVE IN FOR THE WEEKEND. STRONG SFC LOW SPINS NEAR
CANADIAN MARITIMES WITH WEAKER LOW OVER QUEBEC. WEAK TROUGH STILL
EXTENDS WESTWARD ACROSS UPR LAKES REGION FROM THE QUEBEC LOW. HIGH
PRESSURE UPSTREAM OVER MANITOBA WILL ONLY SLOWLY MOVE TOWARD GREAT
LAKES. RESULT IS WEAK CYCLONIC/NEUTRAL LOW-LEVEL FLOW THAT KEEPS
CHANCES OF SNOW SHOWERS/FLURRIES IN THROUGH SATURDAY. AT A MINIMUM...
SKIES ACROSS MUCH OF CWA WILL TEND TO STAY ON THE CLOUDIER SIDE.
BETTER PRECIP CHANCES...AND THEY ARE ON THE SMALLER SIDE...OCCUR
TODAY AS H95-H9 TROUGH DROPS ACROSS LK SUPERIOR INTO NORTHERN CWA
THIS MORNING. PLENTY OF H95-H9 MOISTURE SEEN UPSTREAM IN ONTARIO ON
00Z YPL AND WZC SOUNDINGS. GENERALLY NAM/GFS/LOCAL-WRF INITIALIZED
YPL SOUNDING WELL BUT WERE TOO MOIST ABOVE H95 AT MOOSINEE. ONCE THE
MOISTURE ARRIVES THROUGH 12Z...THINK IT WILL UPSLOPE AND BE LIFTED
OVER COLD DOME OF AIR IN PLACE AND GRADUALLY LOWER/THICKEN. 925-900MB
TEMPS OF -8C TO -10C JUST COLD ENOUGH FOR LK EFFECT SNOW SHOWERS OR
FLURRIES. COVERAGE WILL BE SPOTTY THOUGH AS OVER-WATER INSTABILITY
IS MARGINAL. PUT SOME FZDZ IN EARLIER AS THERE WERE REPORTS UPSTREAM
IN ONTARIO WITH CIGS BLO 010. CIGS THUS FAR OVR UPR MICHIGAN ARE
MORE TOWARD 2KFT WHICH SEEMS TOO HIGH TO SEE ENOUGH SATURATION FOR
FZDZ. WILL PULL THE MENTION OF FZDZ.
STAYED PESSIMISTIC FOR CLOUD COVER TONIGHT GIVEN AMOUNT OF MOISTURE
UPSTREAM. BUT...TONIGHT THERE IS ALSO MORE DIFFLUENT SFC-H9 FLOW SO
CONVERGENCE WILL BE AT A PREMIUM...LEADING TO BREAKS DEVELOPING IN
THE CLOUD COVER. OTHER THAN ISOLD SHSN IN THE EVENING OVR MARQUETTE
COUNTY WITH WEAK ONSHORE/UPSLOPE FLOW...KEPT FORECAST DRY FOR
TONIGHT. MIN TEMPS WILL BE TRICKY AS IT WILL ALL DEPEND ON WHERE
CLOUDS PERSIST. BETTER CHANCE FOR CLEARING WOULD BE OVER SW CWA WITH
MORE OF SIGNAL FOR LGT AND DIFFLUENT WINDS. MIN TEMPS IN THAT AREA
MAY DROP TO 5 ABOVE. ELSEWHERE WITH THE CLOUDS AND SOME WIND...MIN
TEMPS SHOULD STAY IN THE TEENS. ALL IN ALL...PRETTY QUIET WEATHER
COMPARED TO THE ACTIVE WEATHER PATTERN EXPERIENCED RECENTLY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 505 AM EDT FRI MAR 22 2013
A BLOCKING PATTERN WITH HIGH LATITUDE RIDGING FROM GREENLAND INTO
NORTHEAST CANADA IS EXPECTED TO PERSIST THROUGH THE PERIOD. THIS WILL
RESULT IN TROUGHING INTO THE N CNTRL AND ERN CONUS KEEPING BELOW
NORMAL TEMPS IN PLACE. HIGHS IN THE LOWER TO MID 30S ARE EXPECTED
WITH LOWS GENERALLY IN THE TEENS TO LOWER 20S.
SAT INTO SAT NIGHT...EVEN THOUGH MODELS SHOW LARGE SCALE SUBSIDENCE
PREVAILING...WITH PERSISTENT NRLY FLOW AND 825-800MB MOISTURE ALONG
WITH 850 MB TEMPS IN THE -10C TO -12C RANGE...SOME LIGHT LAKE EFFECT
SNOW SHOWERS OR FLURRIES WILL REMAIN POSSIBLE. WITH GREATER LATE
MARCH DAYTIME HEATING...A DIURNAL COMPONENT TO THE -SHSN IS ALSO
EXPECTED. SO...ANY FLURRIES SHOULD DIMINISH DURING THE EVENING.
SUN AND MON...AS A MID LEVEL LOW MOVES EAST FROM THE OHIO
VALLEY...THE GFS/ECMWF SUGGEST THAT ANOTHER BATCH OF 850-700 MB
MOISTURE WILL BE DRAWN TOWARD UPPER MICHIGAN FROM THE NORTHEAST. THE
MOISTURE COMBINED WITH NNE FLOW 850 MB TEMPS REMAINING IN THE -10C
TO -12C RANGE WILL BE ENOUGH TO SUPPORT SNOW SHOWERS CHANCES INTO
THE NW HALF OF THE CWA MON THAT MAY LINGER INTO MON NIGHT.
HOWEVER...ANY SNOWFALL AMOUNT SHOULD REMAIN LIGHT...LESS THAN A HALF
INCH.
TUE-THU...THE ECMWF/GEM WERE SLOWER WITH THE COMPACT MID LEVEL LOW
THAT IS EXPECTED TO SLIDE FROM CNTRL CANADA INTO THE UPPER MS VALLEY
OF WRN GREAT LAKES COMPARED TO THE GFS. DESPITE MODEL DIFFERENCES
REGARDING THIS FEATURE...THE PERSISTENT NRLY LOW LEVEL FLOW PATTERN
WILL KEEP POTENTIAL FOR SOME LIGHT SNOW OR FLURRIES GOING. SINCE ANY
SHORTWAVES IN THE NW MID LEVEL FLOW WILL BE WEAK...EXPECT CHANCE FOR
ANY MEASURABLE SNOW WILL REMAIN ONLY SLIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 144 PM EDT FRI MAR 22 2013
EXPECT -SHSN AND LIGHT DRIZZLE/BR THIS AFTERNOON AT SAW AND CMX TO
DIMINISH AS LOW LEVEL MIXING OCCURS. MOISTURE THEN INCREASES TONIGHT
WITH CONTINUE NLY LOW LEVEL WINDS...SO -FZDZ WILL REOCCUR AS IT DID
THIS MORNING AND CONTINUE INTO SAT MORNING. ONCE LOW LEVEL MIXING
INCREASING LATE SAT MORNING...SHOULD SEE -FZDZ DIMINISH.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 505 AM EDT FRI MAR 22 2013
HIGH PRESSURE OVER CNTRL CANADA EXPANDS INTO THE GREAT LAKES THROUGH
NEXT WEEK. PLAN ON QUIET CONDITIONS ON LK SUPERIOR WITH WINDS LESS
THAN 25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...MRD
SHORT TERM...JLA
LONG TERM...JLB
AVIATION...TITUS
MARINE...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1040 AM EDT FRI MAR 22 2013
.UPDATE...
ISSUED AT 1040 AM EDT FRI MAR 22 2013
SOME SLIGHTLY DEEPER MOISTURE HAS MOVED INTO THE AREA...JUST ENOUGH
TO ALLOW SOME SNOW TO MIX IN WITH THE FREEZING DRIZZLE DUE TO THE
TOP OF THE CLOUD BEING AROUND -12C. HOWEVER...THIS IS EXPECTED TO
ONLY LAST A FEW HOURS PER THE RAP SOUNDINGS. OTHERWISE...HAVE OPTED
TO KEEP FREEZING DRIZZLE AROUND FOR MUCH OF THE DAY CLOSER TO LAKE
SUPERIOR DUE TO THE PERSISTENT UPSLOPE FLOW THROUGH THE DAY AND
SHALLOW MOISTURE. ANY SURFACES THAT ARE UNTREATED MAY BE SLIPPERY AT
TIMES.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 505 AM EDT FRI MAR 22 2013
UPR LEVEL TROUGH DRIFTS FARTHER EAST OF UPR LAKES WITH RIDGING
POISED TO MOVE IN FOR THE WEEKEND. STRONG SFC LOW SPINS NEAR
CANADIAN MARITIMES WITH WEAKER LOW OVER QUEBEC. WEAK TROUGH STILL
EXTENDS WESTWARD ACROSS UPR LAKES REGION FROM THE QUEBEC LOW. HIGH
PRESSURE UPSTREAM OVER MANITOBA WILL ONLY SLOWLY MOVE TOWARD GREAT
LAKES. RESULT IS WEAK CYCLONIC/NEUTRAL LOW-LEVEL FLOW THAT KEEPS
CHANCES OF SNOW SHOWERS/FLURRIES IN THROUGH SATURDAY. AT A MINIMUM...
SKIES ACROSS MUCH OF CWA WILL TEND TO STAY ON THE CLOUDIER SIDE.
BETTER PRECIP CHANCES...AND THEY ARE ON THE SMALLER SIDE...OCCUR
TODAY AS H95-H9 TROUGH DROPS ACROSS LK SUPERIOR INTO NORTHERN CWA
THIS MORNING. PLENTY OF H95-H9 MOISTURE SEEN UPSTREAM IN ONTARIO ON
00Z YPL AND WZC SOUNDINGS. GENERALLY NAM/GFS/LOCAL-WRF INITIALIZED
YPL SOUNDING WELL BUT WERE TOO MOIST ABOVE H95 AT MOOSINEE. ONCE THE
MOISTURE ARRIVES THROUGH 12Z...THINK IT WILL UPSLOPE AND BE LIFTED
OVER COLD DOME OF AIR IN PLACE AND GRADUALLY LOWER/THICKEN. 925-900MB
TEMPS OF -8C TO -10C JUST COLD ENOUGH FOR LK EFFECT SNOW SHOWERS OR
FLURRIES. COVERAGE WILL BE SPOTTY THOUGH AS OVER-WATER INSTABILITY
IS MARGINAL. PUT SOME FZDZ IN EARLIER AS THERE WERE REPORTS UPSTREAM
IN ONTARIO WITH CIGS BLO 010. CIGS THUS FAR OVR UPR MICHIGAN ARE
MORE TOWARD 2KFT WHICH SEEMS TOO HIGH TO SEE ENOUGH SATURATION FOR
FZDZ. WILL PULL THE MENTION OF FZDZ.
STAYED PESSIMISTIC FOR CLOUD COVER TONIGHT GIVEN AMOUNT OF MOISTURE
UPSTREAM. BUT...TONIGHT THERE IS ALSO MORE DIFFLUENT SFC-H9 FLOW SO
CONVERGENCE WILL BE AT A PREMIUM...LEADING TO BREAKS DEVELOPING IN
THE CLOUD COVER. OTHER THAN ISOLD SHSN IN THE EVENING OVR MARQUETTE
COUNTY WITH WEAK ONSHORE/UPSLOPE FLOW...KEPT FORECAST DRY FOR
TONIGHT. MIN TEMPS WILL BE TRICKY AS IT WILL ALL DEPEND ON WHERE
CLOUDS PERSIST. BETTER CHANCE FOR CLEARING WOULD BE OVER SW CWA WITH
MORE OF SIGNAL FOR LGT AND DIFFLUENT WINDS. MIN TEMPS IN THAT AREA
MAY DROP TO 5 ABOVE. ELSEWHERE WITH THE CLOUDS AND SOME WIND...MIN
TEMPS SHOULD STAY IN THE TEENS. ALL IN ALL...PRETTY QUIET WEATHER
COMPARED TO THE ACTIVE WEATHER PATTERN EXPERIENCED RECENTLY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 505 AM EDT FRI MAR 22 2013
A BLOCKING PATTERN WITH HIGH LATITUDE RIDGING FROM GREENLAND INTO
NORTHEAST CANADA IS EXPECTED TO PERSIST THROUGH THE PERIOD. THIS WILL
RESULT IN TROUGHING INTO THE N CNTRL AND ERN CONUS KEEPING BELOW
NORMAL TEMPS IN PLACE. HIGHS IN THE LOWER TO MID 30S ARE EXPECTED
WITH LOWS GENERALLY IN THE TEENS TO LOWER 20S.
SAT INTO SAT NIGHT...EVEN THOUGH MODELS SHOW LARGE SCALE SUBSIDENCE
PREVAILING...WITH PERSISTENT NRLY FLOW AND 825-800MB MOISTURE ALONG
WITH 850 MB TEMPS IN THE -10C TO -12C RANGE...SOME LIGHT LAKE EFFECT
SNOW SHOWERS OR FLURRIES WILL REMAIN POSSIBLE. WITH GREATER LATE
MARCH DAYTIME HEATING...A DIURNAL COMPONENT TO THE -SHSN IS ALSO
EXPECTED. SO...ANY FLURRIES SHOULD DIMINISH DURING THE EVENING.
SUN AND MON...AS A MID LEVEL LOW MOVES EAST FROM THE OHIO
VALLEY...THE GFS/ECMWF SUGGEST THAT ANOTHER BATCH OF 850-700 MB
MOISTURE WILL BE DRAWN TOWARD UPPER MICHIGAN FROM THE NORTHEAST. THE
MOISTURE COMBINED WITH NNE FLOW 850 MB TEMPS REMAINING IN THE -10C
TO -12C RANGE WILL BE ENOUGH TO SUPPORT SNOW SHOWERS CHANCES INTO
THE NW HALF OF THE CWA MON THAT MAY LINGER INTO MON NIGHT.
HOWEVER...ANY SNOWFALL AMOUNT SHOULD REMAIN LIGHT...LESS THAN A HALF
INCH.
TUE-THU...THE ECMWF/GEM WERE SLOWER WITH THE COMPACT MID LEVEL LOW
THAT IS EXPECTED TO SLIDE FROM CNTRL CANADA INTO THE UPPER MS VALLEY
OF WRN GREAT LAKES COMPARED TO THE GFS. DESPITE MODEL DIFFERENCES
REGARDING THIS FEATURE...THE PERSISTENT NRLY LOW LEVEL FLOW PATTERN
WILL KEEP POTENTIAL FOR SOME LIGHT SNOW OR FLURRIES GOING. SINCE ANY
SHORTWAVES IN THE NW MID LEVEL FLOW WILL BE WEAK...EXPECT CHANCE FOR
ANY MEASURABLE SNOW WILL REMAIN ONLY SLIGHT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 745 AM EDT FRI MAR 22 2013
LOW-LEVEL MOISTURE HAS RETURNED TO ALL THE TAF SITES THIS MORNING.
EXPECT LOWER MVFR AND EVEN IFR CIGS THROUGH MORNING. MAY SEE -SHSN
AND FZDZ AT TIMES THIS MORNING. FZDZ PATCHY ENOUGH AT THIS POINT TO
KEEP OUT OF TAFS. EXPECT CLOUDS TO SCATTER OUT THIS EVENING AT IWD
WITH DIFFLUENT LOW-LEVEL WINDS. OTHERWISE...PLAN ON BKN-OVC LOWER
MVFR CIGS CMX AND SAW THROUGH END OF TAF PERIOD WITH PERSISTENT LIGHT
NORTHERLY WINDS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 505 AM EDT FRI MAR 22 2013
HIGH PRESSURE OVER CNTRL CANADA EXPANDS INTO THE GREAT LAKES THROUGH
NEXT WEEK. PLAN ON QUIET CONDITIONS ON LK SUPERIOR WITH WINDS LESS
THAN 25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...MRD
SHORT TERM...JLA
LONG TERM...JLB
AVIATION...JLA
MARINE...JLA
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
753 AM EDT FRI MAR 22 2013
.UPDATE...
ISSUED AT 745 AM EDT FRI MAR 22 2013
FREEZING DRIZZLE HAS INDEED DEVELOPED...AFTER IT WAS REMOVED FROM
FCST. SO IT GOES. ALSO SOME FLURRIES TOO SO IT APPEARS WE ARE RIGHT
ON THE THRESHOLD FOR ICE NUCLEATION. RUC13 925MB TEMPS AROUND -8C SO
THIS MAKES SOME SENSE. ADDED AREAS OF FREEZING DRIZZLE IN OVER HIGHER
TERRAIN OF NW AND NCNTRL UPR MICHIGAN FOR NOW. ALSO PUT OUT SPECIAL
WEATHER STATEMENT AND UPDATED SOCIAL MEDIA TO HIGHLIGHT HAZARD. FOR A
START KEPT MENTION OF FZDZ THROUGH THE MORNING. WOULD THINK THERE MAY
BE ENOUGH MIXING OUT OF NEAR SFC MOISTURE FOR FZDZ TO DISSIPATE BY
AFTN. POSSIBLE THAT FZDZ COULD CONTINUE LONGER FOR UPSLOPE AREAS BUT
NOT QUITE SURE SO WILL LET DAYSHIFT MAKE THAT ADJUSTMENT IF NEEDED.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 505 AM EDT FRI MAR 22 2013
UPR LEVEL TROUGH DRIFTS FARTHER EAST OF UPR LAKES WITH RIDGING
POISED TO MOVE IN FOR THE WEEKEND. STRONG SFC LOW SPINS NEAR
CANADIAN MARITIMES WITH WEAKER LOW OVER QUEBEC. WEAK TROUGH STILL
EXTENDS WESTWARD ACROSS UPR LAKES REGION FROM THE QUEBEC LOW. HIGH
PRESSURE UPSTREAM OVER MANITOBA WILL ONLY SLOWLY MOVE TOWARD GREAT
LAKES. RESULT IS WEAK CYCLONIC/NEUTRAL LOW-LEVEL FLOW THAT KEEPS
CHANCES OF SNOW SHOWERS/FLURRIES IN THROUGH SATURDAY. AT A MINIMUM...
SKIES ACROSS MUCH OF CWA WILL TEND TO STAY ON THE CLOUDIER SIDE.
BETTER PRECIP CHANCES...AND THEY ARE ON THE SMALLER SIDE...OCCUR
TODAY AS H95-H9 TROUGH DROPS ACROSS LK SUPERIOR INTO NORTHERN CWA
THIS MORNING. PLENTY OF H95-H9 MOISTURE SEEN UPSTREAM IN ONTARIO ON
00Z YPL AND WZC SOUNDINGS. GENERALLY NAM/GFS/LOCAL-WRF INITIALIZED
YPL SOUNDING WELL BUT WERE TOO MOIST ABOVE H95 AT MOOSINEE. ONCE THE
MOISTURE ARRIVES THROUGH 12Z...THINK IT WILL UPSLOPE AND BE LIFTED
OVER COLD DOME OF AIR IN PLACE AND GRADUALLY LOWER/THICKEN. 925-900MB
TEMPS OF -8C TO -10C JUST COLD ENOUGH FOR LK EFFECT SNOW SHOWERS OR
FLURRIES. COVERAGE WILL BE SPOTTY THOUGH AS OVER-WATER INSTABILITY
IS MARGINAL. PUT SOME FZDZ IN EARLIER AS THERE WERE REPORTS UPSTREAM
IN ONTARIO WITH CIGS BLO 010. CIGS THUS FAR OVR UPR MICHIGAN ARE
MORE TOWARD 2KFT WHICH SEEMS TOO HIGH TO SEE ENOUGH SATURATION FOR
FZDZ. WILL PULL THE MENTION OF FZDZ.
STAYED PESSIMISTIC FOR CLOUD COVER TONIGHT GIVEN AMOUNT OF MOISTURE
UPSTREAM. BUT...TONIGHT THERE IS ALSO MORE DIFFLUENT SFC-H9 FLOW SO
CONVERGENCE WILL BE AT A PREMIUM...LEADING TO BREAKS DEVELOPING IN
THE CLOUD COVER. OTHER THAN ISOLD SHSN IN THE EVENING OVR MARQUETTE
COUNTY WITH WEAK ONSHORE/UPSLOPE FLOW...KEPT FORECAST DRY FOR
TONIGHT. MIN TEMPS WILL BE TRICKY AS IT WILL ALL DEPEND ON WHERE
CLOUDS PERSIST. BETTER CHANCE FOR CLEARING WOULD BE OVER SW CWA WITH
MORE OF SIGNAL FOR LGT AND DIFFLUENT WINDS. MIN TEMPS IN THAT AREA
MAY DROP TO 5 ABOVE. ELSEWHERE WITH THE CLOUDS AND SOME WIND...MIN
TEMPS SHOULD STAY IN THE TEENS. ALL IN ALL...PRETTY QUIET WEATHER
COMPARED TO THE ACTIVE WEATHER PATTERN EXPERIENCED RECENTLY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 505 AM EDT FRI MAR 22 2013
A BLOCKING PATTERN WITH HIGH LATITUDE RIDGING FROM GREENLAND INTO
NORTHEAST CANADA IS EXPECTED TO PERSIST THROUGH THE PERIOD. THIS WILL
RESULT IN TROUGHING INTO THE N CNTRL AND ERN CONUS KEEPING BELOW
NORMAL TEMPS IN PLACE. HIGHS IN THE LOWER TO MID 30S ARE EXPECTED
WITH LOWS GENERALLY IN THE TEENS TO LOWER 20S.
SAT INTO SAT NIGHT...EVEN THOUGH MODELS SHOW LARGE SCALE SUBSIDENCE
PREVAILING...WITH PERSISTENT NRLY FLOW AND 825-800MB MOISTURE ALONG
WITH 850 MB TEMPS IN THE -10C TO -12C RANGE...SOME LIGHT LAKE EFFECT
SNOW SHOWERS OR FLURRIES WILL REMAIN POSSIBLE. WITH GREATER LATE
MARCH DAYTIME HEATING...A DIURNAL COMPONENT TO THE -SHSN IS ALSO
EXPECTED. SO...ANY FLURRIES SHOULD DIMINISH DURING THE EVENING.
SUN AND MON...AS A MID LEVEL LOW MOVES EAST FROM THE OHIO
VALLEY...THE GFS/ECMWF SUGGEST THAT ANOTHER BATCH OF 850-700 MB
MOISTURE WILL BE DRAWN TOWARD UPPER MICHIGAN FROM THE NORTHEAST. THE
MOISTURE COMBINED WITH NNE FLOW 850 MB TEMPS REMAINING IN THE -10C
TO -12C RANGE WILL BE ENOUGH TO SUPPORT SNOW SHOWERS CHANCES INTO
THE NW HALF OF THE CWA MON THAT MAY LINGER INTO MON NIGHT.
HOWEVER...ANY SNOWFALL AMOUNT SHOULD REMAIN LIGHT...LESS THAN A HALF
INCH.
TUE-THU...THE ECMWF/GEM WERE SLOWER WITH THE COMPACT MID LEVEL LOW
THAT IS EXPECTED TO SLIDE FROM CNTRL CANADA INTO THE UPPER MS VALLEY
OF WRN GREAT LAKES COMPARED TO THE GFS. DESPITE MODEL DIFFERENCES
REGARDING THIS FEATURE...THE PERSISTENT NRLY LOW LEVEL FLOW PATTERN
WILL KEEP POTENTIAL FOR SOME LIGHT SNOW OR FLURRIES GOING. SINCE ANY
SHORTWAVES IN THE NW MID LEVEL FLOW WILL BE WEAK...EXPECT CHANCE FOR
ANY MEASURABLE SNOW WILL REMAIN ONLY SLIGHT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 745 AM EDT FRI MAR 22 2013
LOW-LEVEL MOISTURE HAS RETURNED TO ALL THE TAF SITES THIS MORNING.
EXPECT LOWER MVFR AND EVEN IFR CIGS THROUGH MORNING. MAY SEE -SHSN
AND FZDZ AT TIMES THIS MORNING. FZDZ PATCHY ENOUGH AT THIS POINT TO
KEEP OUT OF TAFS. EXPECT CLOUDS TO SCATTER OUT THIS EVENING AT IWD
WITH DIFFLUENT LOW-LEVEL WINDS. OTHERWISE...PLAN ON BKN-OVC LOWER
MVFR CIGS CMX AND SAW THROUGH END OF TAF PERIOD WITH PERSISTENT LIGHT
NORTHERLY WINDS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 505 AM EDT FRI MAR 22 2013
HIGH PRESSURE OVER CNTRL CANADA EXPANDS INTO THE GREAT LAKES THROUGH
NEXT WEEK. PLAN ON QUIET CONDITIONS ON LK SUPERIOR WITH WINDS LESS
THAN 25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...JLA
LONG TERM...JLB
AVIATION...JLA
MARINE...JLA
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1229 PM CDT FRI MAR 22 2013
.AVIATION...18Z TAF ISSUANCE...
AREAS OF BKN MVFR CIGS ARE LINGERING ACROSS THE REGION EARLY THIS
AFTERNOON WITH A BAND OF MID LVL CLOUDS EXTENDING FROM FGN TO TWM
TO PBH. MVFR CIGS HAVE MOVED IN OVER DLH AND COULD REMAIN THROUGH
THE AFTERNOON WITH A WEAK NE WIND OFF THE LAKE SUPPLEMENTING THE
AVAILABLE MOISTURE. QUITE A BIT OF UNCERTAINTY REGARDING CIG
FORECAST TODAY. A BETTER CHANCE OF LOW CLOUDS TONIGHT. WINDS WILL
REMAIN LIGHT THROUGH THE PERIOD.
&&
.PREV DISCUSSION... /ISSUED 924 AM CDT FRI MAR 22 2013/
UPDATE...PROGRESSIONS OF CLOUDS THROUGH THE ARROWHEAD AND ALONG
THE INTERNATIONAL BORDER HAS SLOWED QUITE A BIT. THERE IS SOME
EROSION OCCURRING ALONG THE LEADING EDGE. HAVE UPDATED THE SKY
GRIDS TO ACCOUNT FOR THIS TREND. RAISED MAX TEMPS A BIT AS TEMPS
ARE RECOVERING QUICKLY WHERE THERE IS FULL SUN...AND ESPECIALLY IN
THE FORESTED AREAS IN NW WI. BROUGHT DEWPOINTS UP AS WELL FOR THE
SAME REASON.
PREV DISCUSSION... /ISSUED 652 AM CDT FRI MAR 22 2013/
AVIATION...12Z TAF ISSUANCE.
A WIDESPREAD STRATUS DECK WITH CEILINGS OF 1-2 KFT IS CURRENTLY
RESIDING OVER ONTARIO...SINKING GRADUALLY OVER NE MINNESOTA AND
WESTERN LAKE SUPERIOR. EXPECTING THE LOW CLOUDS AND MVFR CIGS TO MAINLY
AFFECT THE KINL/KHIB/KDLH TERMINALS THROUGH 18Z...WHERE HAVE
HANDLED WITH TEMPO GROUPS AT THIS TIME. LATEST MODEL RUNS SUGGEST
THE LOW CLOUDS RETREAT BACK TO THE NORTHEAST THROUGH THE LATE
MORNING AND ALLOW WIDESPREAD VFR CIGS ACROSS ALL TERMINALS THIS
AFTERNOON. HOWEVER...THE ANTICIPATED CLEARING IN THE NORTHERN
ZONES WILL BE SHORT LIVED AS ANOTHER ROUND OF LOW CLOUDS ARE
FORECAST TO SPREAD BACK INTO THE REGION OVERNIGHT...MAINLY AFTER
02Z.
PREV DISCUSSION... /ISSUED 259 AM CDT FRI MAR 22 2013/
SHORT TERM...THROUGH SATURDAY.
THE NORTHLAND WILL REMAIN BETWEEN UPPER TROUGHS TODAY...WITH
NARROW RIDGING...THEN WE WILL BECOME INCREASINGLY UNDER THE
INFLUENCE OF THE WESTERN TROUGH AS IT MOVES TOWARD THE REGION
TONIGHT INTO SATURDAY.
THE MAIN FOCUS TODAY WILL BE ON CLOUD COVER...AS LOW LEVEL
NORTHEASTERLY FLOW WAS ALREADY SPREADING CLOUDS INTO THE THE
ARROWHEAD AND THROUGH NORTHWEST ONTARIO. THE NAM...ECMWF AND THE
RAP...WERE DOING A DECENT JOB HANDLING THESE CLOUDS THIS MORNING.
THE ECMWF SUGGESTS THE CLOUDS WILL DIMINISH THIS AFTERNOON...THE
RAP HOLDS THEM IN TODAY AND SPREADS THEM WELL SOUTH INTO OUR CWA.
THE NAM IS A COMPROMISE. WE DO EXPECT SOME THINNING OF THOSE
CLOUDS THIS AFTERNOON...THE RAP WAS WAY OVERDONE YESTERDAY. WE
INCREASED SKY COVER OVER THE NORTHERN AND EASTERN CWA
TODAY...ESPECIALLY THIS MORNING. WE KEPT THE FORECAST DRY TODAY
INTO TONIGHT...BUT WOULD NOT BE SURPRISED IF SOME FLURRIES
DEVELOPED. OVERALL...WE EXPECT HIGHS TODAY FROM 29F TO 35F.
TONIGHT...WITH PERSISTENT LOW LEVEL NORTHEAST FLOW WE EXPECT THE
CLOUDS TO EXPAND WEST AND SOUTH THROUGH MUCH OF THE CWA AND HAVE
MOST AREAS MOSTLY CLOUDY TONIGHT INTO SATURDAY. THE CLOUDS SHOULD
HOLD TEMPS UP TONIGHT...AND WE HAVE THEM FROM 8F TO 14F. SOME
POCKETS OF COLDER TEMPS WILL BE POSSIBLE IN ANY AREAS THAT SEE AN
EXTENDED PERIOD OF MOSTLY CLEAR SKIES...SINCE WINDS WILL BE LIGHT.
A SHORTWAVE WILL ROTATE THROUGH THE AREA ON SATURDAY...AND SHOULD
BE ENOUGH TO SET OFF SOME FLURRIES. WE HAVE SCATTERED FLURRIES
MAINLY OVER OUR MINNESOTA ZONES...INTO FAR NORTHWEST WISCONSIN.
HIGHS SHOULD REBOUND TO 30F TO 35F FOR MOST AREAS.
LONG TERM...SAT NIGHT THROUGH FRIDAY.
THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT
OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH
OVER THE ROCKIES THROUGH THE WEEKEND WITH A PERSISTENT NORTH TO
NORTHEAST BDRY LAYER FLOW. MODELS IN GOOD AGREEMENT THAT A VORT MAX
EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST ACROSS THE SRN
PLAINS THROUGH SUNDAY. MEANWHILE...LATEST MODEL RUNS ARE SUGGESTING A
SHORT WAVE BREAKS FREE FROM MAIN FLOW AND LIFTS INTO THE UPPER
PLAINS. THE 00Z RUNS OF THE ECM/NAM/GFS ALL SHOW THE SHORT WAVE
BECOMES A CLOSED H50 LOW IN THE VCNTY OF MONTANA/WRN DAKOTAS BY
SUNDAY MORNING. ATTM...HAVE KEPT FCST DRY THROUGH THE WEEKEND AS THE
FORCING/PRECIP FROM THE WAVE IN THE DAKOTAS LOOKS TO REMAIN TO THE
WEST OF THE FA...WHILE THE SOUTHERN STREAM LOW STAYS WELL OFF TO THE
SOUTH. HOWEVER...RH FIELDS AND LATEST NAM BUFR SOUNDINGS CONTINUE TO
SHOW INCREASING LOW LEVEL MOISTURE SAT NIGHT/SUN...SO HAVE
INTRODUCED BROAD BRUSH FLURRIES DURING THIS TIME. THE ONSHORE WINDS
MAY ALLOW FOR ADDITIONAL LIFT/ENHANCEMENT TO PRODUCE A FEW LIGHT SNOW
SHOWERS ALONG SOUTH SHORE OF LAKE SUPERIOR SUNDAY THROUGH EARLY NEXT
WEEK.
BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS
MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST.
LATEST RUNS OF THE ECM/GEM/GFS ARE ALL SUGGESTING A H50 CLOSED LOW
RETROGRADES ACROSS HUDSON BAY AND TRACKS INTO MANITOBA THROUGH
MONDAY. FROM HERE THERE ARE LARGE MODEL DIFFERENCES IN THE TRACK OF
THE VORT MAX AS THE ECM KEEPS THE LOW NEARLY STATIONARY OVER
MANITOBA...WHILE THE GFS DROPS THE LOW ACROSS THE DLH CWA THROUGH
MID-WEEK.
&&
.POINT TEMPS/POPS...
DLH 14 34 17 31 / 0 10 10 10
INL 8 33 15 32 / 0 10 10 10
BRD 11 35 18 32 / 0 10 10 10
HYR 8 35 16 34 / 0 10 10 10
ASX 12 34 17 32 / 0 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AVIATION...TENTINGER
AREA FORECAST DISCUSSION
NWS DULUTH MN
924 AM CDT FRI MAR 22 2013
.UPDATE...PROGRESSIONS OF CLOUDS THROUGH THE ARROWHEAD AND ALONG
THE INTERNATIONAL BORDER HAS SLOWED QUITE A BIT. THERE IS SOME
EROSION OCCURRING ALONG THE LEADING EDGE. HAVE UPDATED THE SKY
GRIDS TO ACCOUNT FOR THIS TREND. RAISED MAX TEMPS A BIT AS TEMPS
ARE RECOVERING QUICKLY WHERE THERE IS FULL SUN...AND ESPECIALLY IN
THE FORESTED AREAS IN NW WI. BROUGHT DEWPOINTS UP AS WELL FOR THE
SAME REASON.
&&
.PREV DISCUSSION... /ISSUED 652 AM CDT FRI MAR 22 2013/
AVIATION...12Z TAF ISSUANCE.
A WIDESPREAD STRATUS DECK WITH CEILINGS OF 1-2 KFT IS CURRENTLY
RESIDING OVER ONTARIO...SINKING GRADUALLY OVER NE MINNESOTA AND
WESTERN LAKE SUPERIOR. EXPECTING THE LOW CLOUDS AND MVFR CIGS TO MAINLY
AFFECT THE KINL/KHIB/KDLH TERMINALS THROUGH 18Z...WHERE HAVE
HANDLED WITH TEMPO GROUPS AT THIS TIME. LATEST MODEL RUNS SUGGEST
THE LOW CLOUDS RETREAT BACK TO THE NORTHEAST THROUGH THE LATE
MORNING AND ALLOW WIDESPREAD VFR CIGS ACROSS ALL TERMINALS THIS
AFTERNOON. HOWEVER...THE ANTICIPATED CLEARING IN THE NORTHERN
ZONES WILL BE SHORT LIVED AS ANOTHER ROUND OF LOW CLOUDS ARE
FORECAST TO SPREAD BACK INTO THE REGION OVERNIGHT...MAINLY AFTER
02Z.
PREV DISCUSSION... /ISSUED 259 AM CDT FRI MAR 22 2013/
SHORT TERM...THROUGH SATURDAY.
THE NORTHLAND WILL REMAIN BETWEEN UPPER TROUGHS TODAY...WITH
NARROW RIDGING...THEN WE WILL BECOME INCREASINGLY UNDER THE
INFLUENCE OF THE WESTERN TROUGH AS IT MOVES TOWARD THE REGION
TONIGHT INTO SATURDAY.
THE MAIN FOCUS TODAY WILL BE ON CLOUD COVER...AS LOW LEVEL
NORTHEASTERLY FLOW WAS ALREADY SPREADING CLOUDS INTO THE THE
ARROWHEAD AND THROUGH NORTHWEST ONTARIO. THE NAM...ECMWF AND THE
RAP...WERE DOING A DECENT JOB HANDLING THESE CLOUDS THIS MORNING.
THE ECMWF SUGGESTS THE CLOUDS WILL DIMINISH THIS AFTERNOON...THE
RAP HOLDS THEM IN TODAY AND SPREADS THEM WELL SOUTH INTO OUR CWA.
THE NAM IS A COMPROMISE. WE DO EXPECT SOME THINNING OF THOSE
CLOUDS THIS AFTERNOON...THE RAP WAS WAY OVERDONE YESTERDAY. WE
INCREASED SKY COVER OVER THE NORTHERN AND EASTERN CWA
TODAY...ESPECIALLY THIS MORNING. WE KEPT THE FORECAST DRY TODAY
INTO TONIGHT...BUT WOULD NOT BE SURPRISED IF SOME FLURRIES
DEVELOPED. OVERALL...WE EXPECT HIGHS TODAY FROM 29F TO 35F.
TONIGHT...WITH PERSISTENT LOW LEVEL NORTHEAST FLOW WE EXPECT THE
CLOUDS TO EXPAND WEST AND SOUTH THROUGH MUCH OF THE CWA AND HAVE
MOST AREAS MOSTLY CLOUDY TONIGHT INTO SATURDAY. THE CLOUDS SHOULD
HOLD TEMPS UP TONIGHT...AND WE HAVE THEM FROM 8F TO 14F. SOME
POCKETS OF COLDER TEMPS WILL BE POSSIBLE IN ANY AREAS THAT SEE AN
EXTENDED PERIOD OF MOSTLY CLEAR SKIES...SINCE WINDS WILL BE LIGHT.
A SHORTWAVE WILL ROTATE THROUGH THE AREA ON SATURDAY...AND SHOULD
BE ENOUGH TO SET OFF SOME FLURRIES. WE HAVE SCATTERED FLURRIES
MAINLY OVER OUR MINNESOTA ZONES...INTO FAR NORTHWEST WISCONSIN.
HIGHS SHOULD REBOUND TO 30F TO 35F FOR MOST AREAS.
LONG TERM...SAT NIGHT THROUGH FRIDAY.
THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT
OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH
OVER THE ROCKIES THROUGH THE WEEKEND WITH A PERSISTENT NORTH TO
NORTHEAST BDRY LAYER FLOW. MODELS IN GOOD AGREEMENT THAT A VORT MAX
EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST ACROSS THE SRN
PLAINS THROUGH SUNDAY. MEANWHILE...LATEST MODEL RUNS ARE SUGGESTING A
SHORT WAVE BREAKS FREE FROM MAIN FLOW AND LIFTS INTO THE UPPER
PLAINS. THE 00Z RUNS OF THE ECM/NAM/GFS ALL SHOW THE SHORT WAVE
BECOMES A CLOSED H50 LOW IN THE VCNTY OF MONTANA/WRN DAKOTAS BY
SUNDAY MORNING. ATTM...HAVE KEPT FCST DRY THROUGH THE WEEKEND AS THE
FORCING/PRECIP FROM THE WAVE IN THE DAKOTAS LOOKS TO REMAIN TO THE
WEST OF THE FA...WHILE THE SOUTHERN STREAM LOW STAYS WELL OFF TO THE
SOUTH. HOWEVER...RH FIELDS AND LATEST NAM BUFR SOUNDINGS CONTINUE TO
SHOW INCREASING LOW LEVEL MOISTURE SAT NIGHT/SUN...SO HAVE
INTRODUCED BROAD BRUSH FLURRIES DURING THIS TIME. THE ONSHORE WINDS
MAY ALLOW FOR ADDITIONAL LIFT/ENHANCEMENT TO PRODUCE A FEW LIGHT SNOW
SHOWERS ALONG SOUTH SHORE OF LAKE SUPERIOR SUNDAY THROUGH EARLY NEXT
WEEK.
BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS
MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST.
LATEST RUNS OF THE ECM/GEM/GFS ARE ALL SUGGESTING A H50 CLOSED LOW
RETROGRADES ACROSS HUDSON BAY AND TRACKS INTO MANITOBA THROUGH
MONDAY. FROM HERE THERE ARE LARGE MODEL DIFFERENCES IN THE TRACK OF
THE VORT MAX AS THE ECM KEEPS THE LOW NEARLY STATIONARY OVER
MANITOBA...WHILE THE GFS DROPS THE LOW ACROSS THE DLH CWA THROUGH
MID-WEEK.
&&
.POINT TEMPS/POPS...
DLH 30 15 32 17 / 0 10 10 10
INL 29 10 32 15 / 0 10 10 10
BRD 33 13 33 18 / 0 10 10 10
HYR 33 8 35 16 / 0 10 10 10
ASX 31 11 32 17 / 0 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...GSF
AREA FORECAST DISCUSSION
NWS DULUTH MN
652 AM CDT FRI MAR 22 2013
.AVIATION...12Z TAF ISSUANCE.
A WIDESPREAD STRATUS DECK WITH CEILINGS OF 1-2 KFT IS CURRENTLY
RESIDING OVER ONTARIO...SINKING GRADUALLY OVER NE MINNESOTA AND
WESTERN LAKE SUPERIOR. EXPECTING THE LOW CLOUDS AND MVFR CIGS TO MAINLY
AFFECT THE KINL/KHIB/KDLH TERMINALS THROUGH 18Z...WHERE HAVE
HANDLED WITH TEMPO GROUPS AT THIS TIME. LATEST MODEL RUNS SUGGEST
THE LOW CLOUDS RETREAT BACK TO THE NORTHEAST THROUGH THE LATE
MORNING AND ALLOW WIDESPREAD VFR CIGS ACROSS ALL TERMINALS THIS
AFTERNOON. HOWEVER...THE ANTICIPATED CLEARING IN THE NORTHERN
ZONES WILL BE SHORT LIVED AS ANOTHER ROUND OF LOW CLOUDS ARE
FORECAST TO SPREAD BACK INTO THE REGION OVERNIGHT...MAINLY AFTER
02Z.
&&
.PREV DISCUSSION... /ISSUED 259 AM CDT FRI MAR 22 2013/
SHORT TERM...THROUGH SATURDAY.
THE NORTHLAND WILL REMAIN BETWEEN UPPER TROUGHS TODAY...WITH
NARROW RIDGING...THEN WE WILL BECOME INCREASINGLY UNDER THE
INFLUENCE OF THE WESTERN TROUGH AS IT MOVES TOWARD THE REGION
TONIGHT INTO SATURDAY.
THE MAIN FOCUS TODAY WILL BE ON CLOUD COVER...AS LOW LEVEL
NORTHEASTERLY FLOW WAS ALREADY SPREADING CLOUDS INTO THE THE
ARROWHEAD AND THROUGH NORTHWEST ONTARIO. THE NAM...ECMWF AND THE
RAP...WERE DOING A DECENT JOB HANDLING THESE CLOUDS THIS MORNING.
THE ECMWF SUGGESTS THE CLOUDS WILL DIMINISH THIS AFTERNOON...THE
RAP HOLDS THEM IN TODAY AND SPREADS THEM WELL SOUTH INTO OUR CWA.
THE NAM IS A COMPROMISE. WE DO EXPECT SOME THINNING OF THOSE
CLOUDS THIS AFTERNOON...THE RAP WAS WAY OVERDONE YESTERDAY. WE
INCREASED SKY COVER OVER THE NORTHERN AND EASTERN CWA
TODAY...ESPECIALLY THIS MORNING. WE KEPT THE FORECAST DRY TODAY
INTO TONIGHT...BUT WOULD NOT BE SURPRISED IF SOME FLURRIES
DEVELOPED. OVERALL...WE EXPECT HIGHS TODAY FROM 29F TO 35F.
TONIGHT...WITH PERSISTENT LOW LEVEL NORTHEAST FLOW WE EXPECT THE
CLOUDS TO EXPAND WEST AND SOUTH THROUGH MUCH OF THE CWA AND HAVE
MOST AREAS MOSTLY CLOUDY TONIGHT INTO SATURDAY. THE CLOUDS SHOULD
HOLD TEMPS UP TONIGHT...AND WE HAVE THEM FROM 8F TO 14F. SOME
POCKETS OF COLDER TEMPS WILL BE POSSIBLE IN ANY AREAS THAT SEE AN
EXTENDED PERIOD OF MOSTLY CLEAR SKIES...SINCE WINDS WILL BE LIGHT.
A SHORTWAVE WILL ROTATE THROUGH THE AREA ON SATURDAY...AND SHOULD
BE ENOUGH TO SET OFF SOME FLURRIES. WE HAVE SCATTERED FLURRIES
MAINLY OVER OUR MINNESOTA ZONES...INTO FAR NORTHWEST WISCONSIN.
HIGHS SHOULD REBOUND TO 30F TO 35F FOR MOST AREAS.
LONG TERM...SAT NIGHT THROUGH FRIDAY.
THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT
OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH
OVER THE ROCKIES THROUGH THE WEEKEND WITH A PERSISTENT NORTH TO
NORTHEAST BDRY LAYER FLOW. MODELS IN GOOD AGREEMENT THAT A VORT MAX
EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST ACROSS THE SRN
PLAINS THROUGH SUNDAY. MEANWHILE...LATEST MODEL RUNS ARE SUGGESTING A
SHORT WAVE BREAKS FREE FROM MAIN FLOW AND LIFTS INTO THE UPPER
PLAINS. THE 00Z RUNS OF THE ECM/NAM/GFS ALL SHOW THE SHORT WAVE
BECOMES A CLOSED H50 LOW IN THE VCNY OF MONTANA/WRN DAKOTAS BY
SUNDAY MORNING. ATTM...HAVE KEPT FCST DRY THROUGH THE WEEKEND AS THE
FORCING/PRECIP FROM THE WAVE IN THE DAKOTAS LOOKS TO REMAIN TO THE
WEST OF THE FA...WHILE THE SOUTHERN STREAM LOW STAYS WELL OFF TO THE
SOUTH. HOWEVER...RH FIELDS AND LATEST NAM BUFR SOUNDINGS CONTINUE TO
SHOW INCREASING LOW LEVEL MOISTURE SAT NIGHT/SUN...SO HAVE
INTRODUCED BROADBRUSH FLURRIES DURING THIS TIME. THE ONSHORE WINDS
MAY ALLOW FOR ADDITIONAL LIFT/ENHANCEMENT TO PRODUCE A FEW LIGHT SNOW
SHOWERS ALONG SOUTH SHORE OF LAKE SUPERIOR SUNDAY THROUGH EARLY NEXT
WEEK.
BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS
MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST.
LATEST RUNS OF THE ECM/GEM/GFS ARE ALL SUGGESTING A H50 CLOSED LOW
RETROGRADES ACROSS HUDSON BAY AND TRACKS INTO MANITOBA THROUGH
MONDAY. FROM HERE THERE ARE LARGE MODEL DIFFERENCES IN THE TRACK OF
THE VORT MAX AS THE ECM KEEPS THE LOW NEARLY STATIONARY OVER
MANITOBA...WHILE THE GFS DROPS THE LOW ACROSS THE DLH CWA THROUGH
MID-WEEK.
&&
.POINT TEMPS/POPS...
DLH 31 15 32 17 / 10 10 10 10
INL 30 10 32 15 / 10 10 10 10
BRD 32 13 33 18 / 0 10 10 10
HYR 33 8 35 16 / 0 10 10 10
ASX 31 11 32 17 / 10 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS DULUTH MN
259 AM CDT FRI MAR 22 2013
.SHORT TERM...THROUGH SATURDAY.
THE NORTHLAND WILL REMAIN BETWEEN UPPER TROUGHS TODAY...WITH
NARROW RIDGING...THEN WE WILL BECOME INCREASINGLY UNDER THE
INFLUENCE OF THE WESTERN TROUGH AS IT MOVES TOWARD THE REGION
TONIGHT INTO SATURDAY.
THE MAIN FOCUS TODAY WILL BE ON CLOUD COVER...AS LOW LEVEL
NORTHEASTERLY FLOW WAS ALREADY SPREADING CLOUDS INTO THE THE
ARROWHEAD AND THROUGH NORTHWEST ONTARIO. THE NAM...ECMWF AND THE
RAP...WERE DOING A DECENT JOB HANDLING THESE CLOUDS THIS MORNING.
THE ECMWF SUGGESTS THE CLOUDS WILL DIMINISH THIS AFTERNOON...THE
RAP HOLDS THEM IN TODAY AND SPREADS THEM WELL SOUTH INTO OUR CWA.
THE NAM IS A COMPROMISE. WE DO EXPECT SOME THINNING OF THOSE
CLOUDS THIS AFTERNOON...THE RAP WAS WAY OVERDONE YESTERDAY. WE
INCREASED SKY COVER OVER THE NORTHERN AND EASTERN CWA
TODAY...ESPECIALLY THIS MORNING. WE KEPT THE FORECAST DRY TODAY
INTO TONIGHT...BUT WOULD NOT BE SURPRISED IF SOME FLURRIES
DEVELOPED. OVERALL...WE EXPECT HIGHS TODAY FROM 29F TO 35F.
TONIGHT...WITH PERSISTENT LOW LEVEL NORTHEAST FLOW WE EXPECT THE
CLOUDS TO EXPAND WEST AND SOUTH THROUGH MUCH OF THE CWA AND HAVE
MOST AREAS MOSTLY CLOUDY TONIGHT INTO SATURDAY. THE CLOUDS SHOULD
HOLD TEMPS UP TONIGHT...AND WE HAVE THEM FROM 8F TO 14F. SOME
POCKETS OF COLDER TEMPS WILL BE POSSIBLE IN ANY AREAS THAT SEE AN
EXTENDED PERIOD OF MOSTLY CLEAR SKIES...SINCE WINDS WILL BE LIGHT.
A SHORTWAVE WILL ROTATE THROUGH THE AREA ON SATURDAY...AND SHOULD
BE ENOUGH TO SET OFF SOME FLURRIES. WE HAVE SCATTERED FLURRIES
MAINLY OVER OUR MINNESOTA ZONES...INTO FAR NORTHWEST WISCONSIN.
HIGHS SHOULD REBOUND TO 30F TO 35F FOR MOST AREAS.
.LONG TERM...SAT NIGHT THROUGH FRIDAY.
THE WESTERN LAKE SUPERIOR REGION WILL SITUATED BETWEEN A LARGE CUT
OFF LOW ROTATING OVER THE NEW ENGLAND STATES...AND A DIGGING TROUGH
OVER THE ROCKIES THROUGH THE WEEKEND WITH A PERSISTENT NORTH TO
NORTHEAST BDRY LAYER FLOW. MODELS IN GOOD AGREEMENT THAT A VORT MAX
EJECTS OUT OF THE BASE OF THE TROUGH AND TRACKS EAST ACROSS THE SRN
PLAINS THROUGH SUNDAY. MEANWHILE...LATEST MODEL RUNS ARE SUGGESTING A
SHORT WAVE BREAKS FREE FROM MAIN FLOW AND LIFTS INTO THE UPPER
PLAINS. THE 00Z RUNS OF THE ECM/NAM/GFS ALL SHOW THE SHORT WAVE
BECOMES A CLOSED H50 LOW IN THE VCNTY OF MONTANA/WRN DAKOTAS BY
SUNDAY MORNING. ATTM...HAVE KEPT FCST DRY THROUGH THE WEEKEND AS THE
FORCING/PRECIP FROM THE WAVE IN THE DAKOTAS LOOKS TO REMAIN TO THE
WEST OF THE FA...WHILE THE SOUTHERN STREAM LOW STAYS WELL OFF TO THE
SOUTH. HOWEVER...RH FIELDS AND LATEST NAM BUFR SOUNDINGS CONTINUE TO
SHOW INCREASING LOW LEVEL MOISTURE SAT NIGHT/SUN...SO HAVE
INTRODUCED BROADBRUSH FLURRIES DURING THIS TIME. THE ONSHORE WINDS
MAY ALLOW FOR ADDITIONAL LIFT/ENHANCEMENT TO PRODUCE A FEW LIGHT SNOW
SHOWERS ALONG SOUTH SHORE OF LAKE SUPERIOR SUNDAY THROUGH EARLY NEXT
WEEK.
BEYOND THE WEEKEND...THE H50 FLOW BECOMES VERY DISORGANIZED AS
MODELS TRY TO RESOLVE PHASING THE DOUBLE LOWS OVER THE ERN COAST.
LATEST RUNS OF THE ECM/GEM/GFS ARE ALL SUGGESTING A H50 CLOSED LOW
RETROGRADES ACROSS HUDSON BAY AND TRACKS INTO MANITOBA THROUGH
MONDAY. FROM HERE THERE ARE LARGE MODEL DIFFERENCES IN THE TRACK OF
THE VORT MAX AS THE ECM KEEPS THE LOW NEARLY STATIONARY OVER
MANITOBA...WHILE THE GFS DROPS THE LOW ACROSS THE DLH CWA THROUGH
MID-WEEK.
&&
.AVIATION...
A STRATUS DECK WITH CEILINGS AROUND 2 KFT SEEN ON SATELLITE
IMAGERY OVER ONTARIO...WILL PUSH SOUTH AND WEST INTO THE FORECAST
AREA THROUGH DAYBREAK. THIS AREA OF LOW CLOUDS IS EXPECTED TO
MAINLY AFFECT THE THE KINL AND KHIB TERMINALS WHERE HAVE ADDED A
TEMPO FOR MVFR CIGS...THROUGH THE EARLY MORNING. ELSEWHERE...CLEAR
SKIES AND VFR CIGS WILL PREVAIL WITH A BRIEF PERIOD OF LOWER VSBYS
DUE TO LIGHT FG/BR POSSIBLE THROUGH 12Z.
&&
.POINT TEMPS/POPS...
DLH 31 15 32 17 / 10 10 10 10
INL 30 10 32 15 / 10 10 10 10
BRD 32 13 33 18 / 0 10 10 10
HYR 33 8 35 16 / 0 10 10 10
ASX 31 11 32 17 / 10 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...MELDE
LONG TERM....GRANING
AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS DULUTH MN
109 AM CDT FRI MAR 22 2013
.AVIATION...06Z TAF ISSUANCE...
CLOUDS LINGER OVER THE MN ARROWHEAD TOWARDS THE TWIN PORTS HOWEVER
CEILINGS REMAIN VFR FOR THE MAJORITY OF THE SITES. EXPECT VFR TO
PREVAIL THIS PERIOD ALTHOUGH A BRIEF PERIOD OF MVFR MAY DEVELOP OVER
NRN/ERN TERMINALS.
&&
PREV DISCUSSION... /ISSUED 308 PM CDT THU MAR 21 2013/
SHORT TERM.../NOW - FRIDAY/
AT 3PM/2000Z...THERE WAS A RIDGE OF HIGH PRESSURE OVER THE
NORTHERN PLAINS AND SOUTHERN MINNESOTA. THE NORTHLAND HAD LIGHT NW
WINDS DUE TO A LARGE LOW PRESSURE SYSTEM OVER THE NORTHEASTERN
UNITED STATES AND SOUTHEASTERN CANADA. MOST OF THE NORTHLAND HAD
SUNNY TO MOSTLY SUNNY SKIES...BUT THERE WAS STILL SOME LINGERING
LAKE EFFECT SNOW RELATED OVC CLOUDS OVER THE FAR EASTERN FORECAST
AREA IN NW WISCONSIN. THE OVC CLOUDS WERE QUICKLY DIMINISHING AS
THE WINDS WEAKENED OVER WESTERN LAKE SUPERIOR...CUTTING OFF THE
MOISTURE SUPPLY. TEMPERATURES WERE IN THE LOWER TO UPPER 20S
ACROSS THE NORTHLAND.
TONIGHT...THE HIGH PRESSURE IN THE NORTHERN PLAINS WILL SLOWLY
MOVE INTO THE NORTHLAND. THE NORTHLAND CAN EXPECT CLEAR TO MOSTLY
CLEAR SKIES. THERE COULD BE SOME CLOUDS OVER THE TIP OF THE
ARROWHEAD LATE TONIGHT. THE NAM AND RAP INDICATE SOME ENHANCED LOW
LEVEL MOISTURE MOVING INTO THAT AREA...BUT LEANED ON A CLEAR
FORECAST. THE MODEL GUIDANCE IS LIKELY MUCH TOO WARM CONSIDERING
THE CLEAR SKIES AND VERY LIGHT WINDS EXPECTED FOR TONIGHT...SO
UNDERCUT THE MODEL CONSENSUS BY SEVERAL DEGREES. OVERNIGHT LOWS
WILL PROBABLY BE WELL INTO THE SINGLE DIGITS BELOW ZERO ACROSS
MOST OF THE NORTHLAND.
FRIDAY...THE HIGH PRESSURE OVER THE NORTHLAND WILL PROMOTE SUNNY
TO MOSTLY SUNNY SKIES FOR AT LEAST THE MORNING. THERE COULD BE
SOME INCREASING CLOUD COVER IN THE AFTERNOON BASED ON MODEL RH.
HOWEVER...LEANED ON LESS CLOUD COVER SINCE THE MODELS SEEM TO BE
EXAGGERATING THE POTENTIAL FOR CLOUD COVER. FRIDAY COULD VERY
EASILY BE SUNNY ACROSS THE REGION...SO UPDATES MIGHT NEED TO BE
MADE IN THE FUTURE. HIGH TEMPERATURES WILL LIKELY BE IN THE LOWER
30S.
LONG TERM.../FRIDAY NIGHT - WEDNESDAY NIGHT/
CONTINUED QUIET WEATHER CONDITIONS THROUGH THE WEEKEND AND INTO
THE MIDDLE OF NEXT WEEK WITH A NARROW RIDGE OF HIGH PRESSURE
SITUATED OVER THE UPPER MIDWEST BETWEEN TWO SLOW MOVING UPPER
LOWS. THE LOW TO THE WEST WILL EVENTUALLY UNDERCUT THE HIGH
PRESSURE BY THIS WEEKEND. HOWEVER...THE ACTIVE PATTERN WILL REMAIN
WELL TO THE SOUTH AND LEAVE THE NORTHLAND MOSTLY DEVOID OF
PRECIPITATION. THE LOW LEVEL FLOW WILL BE FAVORABLE FOR A
PERSISTENT E/NE WIND OFF LAKE SUPERIOR AND KEEP MUCH OF THE
NORTHLAND UNDER THE INFLUENCE OF MOSTLY CLOUDY SKIES THROUGH THE
WEEK. THE LACK OF SUN...COMBINED WITH A RELATIVELY COLD AIR
MASS...850MB TEMPS -11 DEG C...WILL KEEP AFTERNOON HIGHS IN THE
LOWER 30S AND OVERNIGHT LOWS IN THE TEENS. ROUGHLY 5-10 DEG BELOW
AVERAGE. COULD SEE A FEW WEAK WAVES ROTATE WWD FROM THE UPPER
TROUGH OVER ERN CANADA EARLY NEXT WEEK...BUT ONLY A SLIGHT CHANCE
OF LIGHT SNOW IS POSSIBLE FROM THESE...WITH LITTLE TO NO SNOW
ACCUMULATING.
&&
.POINT TEMPS/POPS...
DLH 12 32 16 32 / 10 10 10 10
INL 9 31 16 32 / 10 10 10 10
BRD 12 33 19 33 / 0 10 10 10
HYR 8 34 16 34 / 0 10 0 10
ASX 11 32 16 33 / 0 0 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1011 PM EDT SAT MAR 23 2013
.SYNOPSIS...
A COLD MOIST NORTHWEST FLOW...WILL KEEP SCATTERED SNOW SHOWERS
AND FLURRIES ACROSS MUCH OF THE AREA...INTO EARLY SUNDAY.
THEREAFTER...HIGH PRESSURE WILL BRIEFLY BUILD IN...TO BRING DRY
WEATHER MOST OF SUNDAY AND SUNDAY NIGHT. ON MONDAY...A COMPLEX
STORM SYSTEM IS EXPECTED TO ORGANIZE...ALONG THE MID-ATLANTIC
COAST. THIS SYSTEM HAS THE POTENTIAL...TO BRING SNOW TO PORTIONS
OF THE REGION...WITH THE GREATEST LIKELIHOOD OF ACCUMULATING
SNOWFALL...OVER NORTHEAST PENNSYLVANIA.
&&
.NEAR TERM /THROUGH SUNDAY/...
1010 PM UPDATE...
TEMPS WERE RAISED ABOUT A DEGREE OVERNIGHT DUE TO LAKE ENHANCED
CLOUDS AND FLURRIES STREAMING ACROSS INTERIOR FA. PULLED BACK ON
THE POPS OVER NORTHERN FA EARLY, CONFINING MOST OF THE ACTIVITY TO
SE OF THE FINGER LAKES. BASED ON RAP AND WRFARW WIND PROFILES,
TREND THE SNOW SHOWERS BACK NORTHWARD AS THE ACTIVITY WANES LATE
OVERNIGHT.
750 PM UPDATE...
OPTED TO INCREASE POPS TONIGHT AS LES HAS BLOSSOMED AFTER SUNSET.
HOWEVER SAW NO REASON TO INCREASE SNOW AMOUNTS DUE TO VERY LIGHT
SNOWFALL AND LACK OF SNOW GROWTH. EXTENDED FLURRY ACTIVITY TO THE
SOUTH INTO THE WYOMING VALLEY OF PA.
TEMPS/WINDS IN EXCELLENT SHAPE.
325 PM UPDATE... MULTI-BAND LES REMAINS ACRS PTNS OF CNY LATE THIS
AFTN...ALTHOUGH INTENSITY/ORGANIZATION HAS BEEN COMPROMISED BY
BOTH DECREASING MOISTURE SUPPLY...AND DIURNAL HEATING/BLYR INSTAB.
ALTHOUGH TERRESTRIAL STABILITY WILL INCREASE AGN THIS
EVE...MOISTURE SUPPLY WILL REMAIN FAIRLY SHALLOW...SO MAINLY JUST
FLRYS AND SCTD -SHSN ARE ANTICIPATED OVERNIGHT INTO EARLY
SUN...WITH LITTLE TO NO ADDTNL ACCUMS.
MUCH OF THE DAY SUN SHOULD BE PCPN-FREE...WITH BREAKS OF SUNSHINE
BY AFTN...AS A SFC RIDGE NOSES DOWN FROM ERN CANADA. HIGH TEMPS
WILL REMAIN CHILLY...DESPITE SOME SUN...WITH THE AMS ONLY
SUPPORTING READINGS IN THE UPR 30S TO LWR 40S.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
345 PM UPDATE... THE MAIN SYSTEM OF INTEREST REMAINS THE WV
TRACKING EWD FROM THE OH/TN VLYS TWDS THE MID-ATL COAST LTR SUN
NGT THROUGH MON. NWP CONSENSUS CONTS TO SUGGEST AN UNPHASED SYSTEM
(SEPARATE NRN AND SRN STREAMS) TIL QUITE LATE IN THE EVENT (MON
NGT INTO TUE)...ONCE THE SYSTEM IS ALREADY OFF THE ERN SEABOARD.
ALSO...THE PERSISTENCE OF AN UPR-LVL VORTEX NEAR THE CANADIAN
MARITIMES (CONFLUENT FLOW UNDERNEATH IT)...SHOULD MEAN A FAIRLY
QUICK EXIT TO THE E...ONCE THE CYCLONE REACHES THE MD/VA COASTAL
WATERS.
BOTTOM LN...A QUICK SHOT OF LIFT AND MOISTURE ADVECTION DURG THE
DAY MON...WILL LIKELY BRING A SHORT-LIVED PD OF SNOW. OWING TO
THE PRESENCE OF THE MARITIME UPR LOW MENTIONED ABV...IT APPEARS
THERE IS ONLY SO FAR N THE PCPN SHIELD WILL BE ABLE TO GO...AND
CURRENT MODEL CONSENSUS PAINTS THIS "LINE IN THE SAND" NEAR THE
PA/NY BORDER. POP/QPF/SNOW GRIDS WERE ONLY TWEAKED SLIGHTLY FROM
PERSISTENCE...WITH LIKELY POPS MAINLY CONFINED TO NE PA/SULLIVAN
CNTY...WHERE 1-4" OF SNOW COULD POTENTIALLY FALL. FARTHER N ACRS
CNY...LTL OR NO SNOWFALL SEEMS LIKE THE MOST LIKELY OUTCOME ATTM.
WE`LL CONTINUE TO HIGHLIGHT THIS SYSTEM FOR OUR SRN ZNS IN THE
HWO.
BY TUE...WITH THE COASTAL CYCLONE WELL TO OUR E...A WEAK N TO NW
FLOW WILL RESUME...WITH MORE FLRYS/-SHSN IN THE VICINITY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LTL CHG FROM PREV FCST WITH THE RGN REMAINING UNDER NW FLOW (AFTER
THE DEPARTURE OF THE EARLY WEEK MID ATLC CST STORM)...AND GNRL
UPR LVL TROFFINESS. HPC DATA WAS UTILIZED AS THE BASELINE FCST...BUT
WE ADJUSTED SOME MID-WEEK CLD/POP GRIDS TO INDICATE LOW CHC POPS FOR
-SHSN IN THIS NW FLOW PTRN ACRS CNTRL NY. A VERY GRADUAL MODIFICATION
OF THE COLD TEMPS BY LATE IN THE WORK WEEK.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
NW FLOW WILL CONT THRU THE PD BRINGING LAKE MOISTURE INTO THE
REGION. THIS WILL RESULT IN OCNL LGT SNOW SHWRS...ALONG WITH NGT
TIME MVFR CIGS. DAYLIGHT HRS WILL BRING BETTER MIXING AND LL DRY
AIR SO CIGS WILL RETURN TO VFR LVLS. FLOW WILL SUPPORT NW
WINDS...BCMG GUSTY DURING THE DAYLIGHT HRS.
.OUTLOOK...
SUN NGT...PATCHY MVFR CNTRL NY.
MON/MON NGT...MVFR CNTRL NY IN -SHSN...IFR/MVFR NE PA IN SNOW.
TUE/WED/THU/FRI...PATCHY MVFR IN -SHSN MAINLY CNTRL NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJP/MLJ
NEAR TERM...MLJ
SHORT TERM...MLJ
LONG TERM...
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
133 AM CDT FRI MAR 22 2013
.DISCUSSION...
MAIN UPDATES WERE TO ADJUST THE EASTWARD PROGRESSION OF THE SNOW
BAND...ADJUST SKY COVER BASED ON LATEST SAT IMAGERY...AND TO
ADJUST TEMPERATURES BASED ON LATEST OBSERVATIONS AND HR NEAR TERM
MODEL DATA. OVERALL...UPDATES WERE MINOR WITH THE INHERITED
FORECAST ON TRACK.
LATEST RADAR IMAGERY/SURFACE OBSERVATIONS CONTINUE TO
SHOW LIGHT SNOW BAND IN THE WEST WITH A SLIGHT MOVEMENT
EASTBOUND. THE RAP MAINTAINS A VERY SLOW PROGRESSION EAST THROUGH
FRIDAY AFTERNOON. WATER VAPOR IMAGERY SHOWS AN UPPER LOW BEGINNING
TO FORM OVER NORTH CENTRAL MONTANA WITH A SURFACE LOW BASICALLY
UNDERNEATH THE UPPER LOW FORMATION. THE SURFACE/UPPER AIR LOW IS
FORECAST TO MOVE TO NEAR BAKER MONTANA BY 12Z FRIDAY.
HENCE...EXPECT A CONTINUATION OF A FAIRLY SHARP DELINEATION FROM
SNOW TO NO SNOW. STILL LOOKS LIKE MID TO LATE MORNING FOR THE SNOW
TO ENTER THE BISMARCK AND MINOT AREAS.
&&
.AVIATION...
FOR THE 06Z FRIDAY TAF ISSUANCE...LIGHT SNOW WILL CONTINUE ACROSS
THE WESTERN AERODROMES OF KISN/KDIK WITH MVFR/IFR CIGS AND VSBYS
THROUGH FRIDAY AFTERNOON. LOW IFR/MVFR CIGS AT KBIS/KMOT ARE
EXPECTED TO DEVELOP BY AROUND 09Z FRIDAY...WITH LIGHT SNOW AND
MVFR VSBYS INITIATING BETWEEN 15Z AND 18Z FRIDAY. EXPECT SCT TO
BKN MVFR CIGS AND PATCHY FOG AT KJMS BY AROUND 09Z
FRIDAY...HOWEVER NO SNOWFALL OCCURRING UNTIL 22Z FRIDAY WITH MVFR
CIGS COMMENCING AT THAT TIME.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
AVIATION...KS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
448 AM EDT FRI MAR 22 2013
.SYNOPSIS...
AN UPPER LEVEL LOW OVER THE CANADIAN MARITIMES WILL REMAIN
NEARLY STATIONARY INTO THE WEEKEND. A NEW STORM SYSTEM MOVING OUT
OF THE OF THE MID- MISSISSIPPI VALLEY LATER THIS WEEKEND COULD
BRING ANOTHER ROUND OF WINTRY PRECIPITATION TO THE REGION LATE
SUNDAY NIGHT AND MONDAY.
THE UNUSUAL BLOCKING PATTERN IN THE UPPER ATMOSPHERE IS EXPECTED
TO KEEP THE PERSISTENT CHILL IN THE AIR RIGHT THROUGH THE END OF
THE MONTH.
&&
.NEAR TERM /THROUGH TODAY/...
AT LEAST TWO LAKE EFFECT SNOW BANDS MANAGED TO MEANDER DOWN INTO
THE CENTRAL MOUNTAINS OVER THE LAST SEVERAL HOURS LEAVING A FRESH
COATING OF SNOW HERE AT THE OFFICE. OTHERWISE THE PATTERN HAS NOT
CHANGED SIGNIFICANTLY...WITH MINOR DISTURBANCES BEING CHANNELED DOWN
THE PERSISTENT COLD NW FLOW...OCCASIONALLY GIVING A POSITIVE BOOST
TO THE VERTICAL MOTIONS.
IT FINALLY LOOKS LIKE WE WILL SEE AT LEAST SOME MINOR IMPROVEMENT
TODAY AS HEIGHTS ALOFT BEGIN TO RISE...INVERSION HEIGHTS COME
DOWN AND LOW LEVEL WINDS BECOME MORE WESTERLY. HAVE NOT CHANGED
THE TIMING OF THE LAKE SNOW ADVISORY SINCE IT LOOKS GOOD FOR THE
SNOW SHOWERS TO BECOME LESS ORGANIZED AS WE GET DEEPER INTO THE
DAY.
TODAY`S HIGHS RANGING FROM THE MID 20S TO MID 40S FROM NW TO SE
WILL BE SOME 10 TO 20 DEG BELOW NORMAL AS THIS UNUSUAL EARLY SPRING
CHILL CONTINUES LOCKED IN OVER THE REGION.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/...
ANY LINGERING SNOW SHOWERS OVER NWRN AREAS WILL TAPER TO FLURRIES
TONIGHT AS WE FINALLY START TO LOSE THE MOIST CYCLONIC FLOW ON THE
BACK SIDE OF THE CANADIAN LOW. SKIES WILL SCATTER OUT OVER MOST
OF THE FORECAST AREA...ALLOWING TEMPS TO FALL BACK INTO THE TEENS
AND 20S...STILL WELL BELOW NORMAL FOR LATE MARCH.
SATURDAY WILL REPRESENT A PERIOD OF BRIEF TRANQUILITY IN THE WAKE
OF THE SLOW MOVING LOW THAT HAS BEEN KEEPING US CLOUDY-COLD AND
UNSETTLED. HIGH PRESSURE WILL NOSE IN FROM THE LAKES WITH AT LEAST
SOME DRIER WEATHER...THOUGH IT WILL NOT BE SIGNIFICANTLY WARMER
THAN TODAY.
ANY LINGERING FLURRIES WILL REMAIN VERY NEAR AND DOWNWIND OF LAKE
ERIE.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
THE EXTENDED FORECAST WILL BE DOMINATED BY THE PROSPECTS OF YET
MORE LATE WINTER/EARLY SPRING WINTRY WEATHER.
MODELS ARE IN GOOD ACCORD WITH BRINGING A NEW TROF/UPPER LOW
SWINGING AROUND UNDER THE NORTHERN CANADIAN BLOCKING HIGH...AND
TRACKING IT EAST TOWARD THE MID ATLANTIC STATES. THE BIG QUESTIONS
CENTER ON HOW CLOSE THE PRIMARY AND SECONDARY STORMS MANAGE TO
GET TO THE LOCAL AREA AND HOW MUCH PRECIP THEY WILL PRODUCE.
THE 00Z NAM IS VERY AGGRESSIVE AND IMPLIES WE COULD SEE WIDESPREAD
SNOWS IN EXCESS OF 6 INCHES. THE GFS IS SLIGHTLY LESS AGGRESSIVE
BUT STILL IMPLIES WARNING SNOWS FOR MUCH OF CENTRAL AND SOUTHERN
PA. THE ECMWF IS MUCH DRIER...WITH ABOUT .25 TO LESS THAN .50"
QPF OVER THE SRN HALF OF THE FCST AREA.
THE SREF/GEFS BOTH SHOW A HIGH LIKELIHOOD OF AT LEAST .25"/12HR
QPF...WITH THE CHANCES FOR .50"/12HR RUNNING IN THE 50-70% RANGE.
MUCH BOTHERS ME ABOUT THE SREF/GEFS/NAM/GFS SCENARIOS.
TRADITIONALLY WE DO NOT DO REAL WELL FROM THESE MILLER TYPE B
REDEVELOPING LOWS UNLESS THE COASTAL LOW BECOMES THE BIG PRECIP
PLAYER LOCALLY. IT SEEMS THE OPERATIONAL MODELS WANT MOST OF OUR
PRECIP TO BE ASSOCIATED WITH THE DYING PRIMARY LOW AND I AM HARD
PRESSED TO RECALL AN EVENT WHERE WE GOT MORE THAN 6" OF SNOW FROM
SUCH A SET UP. IT SEEMS THE MOISTURE USUALLY RAPIDLY SHIFTS TO
THE COASTAL LOW AND WE GET HIT HARD ONLY IF THE COASTAL TRACKS
CLOSE ENOUGH...WHICH ALL BUT THE NAM ARE INDICATING WILL NOT
HAPPEN.
THE ENSEMBLES HAVE THE REQUISITE ANOMALOUS EASTERLY LOW LEVEL JET
WHICH IS A CHECK MARK ON THE FAVORABLE SIDE OF THE LEDGER...BUT
THE BEST PWATS NEVER GET ANYWHERE NEAR THE REGION...BEING RAPIDLY
PINCHED OFF AND SHUNTED WELL OUT INTO THE ATLANTIC.
OUR MOST RECENT STORM QPF WAS OFF BADLY...BY ABOUT HALF...PERHAPS
BY THE NORTHERN EDGE OF THE PRECIP BEING ROBBED OF MOISTURE BY
CONVECTION FURTHER SOUTH...AND I HAVE TO WONDER IF THIS WILL
HAPPEN AGAIN AS THE MODELS DO INDICATE INSTABILITY SURGING NORTH
TOWARD BOTH THE PRIMARY AND EXPECTED COASTAL LOWS.
AT THIS POINT WE HAVE SNOW/RAIN INDICATED FOR SUNDAY INTO
MONDAY...BUT CONFIDENCE IS VERY LOW AS TO QUANTITIES.
AFTER THE STORM GOES BY...WE ONCE AGAIN LOCK IN UNDER A DEEP NW
FLOW UNDER THE AMAZINGLY PERSISTENT NORTHERN CANADA/GREENLAND
UPPER BLOCKING HIGH. THE GEFS SHOWS THIS RIDGE TO STAY IN PLACE
THROUGH ABOUT MID WEEK WHEN IT FINALLY SHOWS SIGNS OF THE BLOCK
BEGINNING TO BREAK DOWN.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
A COLD NORTHWEST FLOW WILL GATHER MOISTURE FROM THE GREAT LAKES
AND DEPOSIT IT AS SNOW SHOWERS ACROSS THE ALLEGHENY MOUNTAINS
TONIGHT AND FRIDAY. SOME OF THE HEAVIEST SNOW SHOWERS WITH
IFR VSBYS WILL LIKELY OCCUR BTWN 04Z-08Z AT JST WITH PASSAGE OF A
WEAK SFC TROUGH. LATEST RUC SHOWS A TONGUE OF HIGHER LOW LVL
MOISTURE ALONG THIS BOUNDARY SAGGING SOUTH INTO THE LAUREL
HIGHLANDS DURING THIS TIME PERIOD. DRYING...DOWNSLOPING FLOW
SHOULD RESULT IN MUCH BETTER FLYING CONDS OVERNIGHT EAST OF THE
MTNS. CAN/T RULE OUT BRIEF VSBY RESTRICTIONS OVERNIGHT AT
AOO/UNV/IPT...WHILE CONDS AT MDT AND LNS APPEAR VERY LIKELY TO
REMAIN VFR.
EXPECT DIMINISHING -SHSN OVR THE W MTNS ON FRIDAY...AS INVERSION
HEIGHTS LOWER WITH APPROACH OF SFC HIGH. STILL...OCNL MVFR
CIGS/VSBYS REMAIN POSSIBLE AT BFD THRU FRI EVENING. AN INTENSE LOW
PRES SYSTEM OVR THE CANADIAN MARITIMES WILL CONTINUE TO BUFFET THE
AREA WITH A GUSTY WNW WINDS. ALTHOUGH THE GUSTS MAY DIMINISH A BIT
OVERNIGHT...BUFKIT SOUNDINGS SUPPORT WIDESPREAD GUSTS ARND 25KTS
DURING LATE FRI AM AND AFTERNOON.
OUTLOOK...
SAT...NO SIG WX EXPECTED.
SUN...SNOW POSS LATE ACROSS THE SOUTH.
MON...SNOW POSS...ESP SOUTH.
TUE...SNOW POSS...ESP LAUREL HIGHLANDS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY UNTIL NOON EDT TODAY FOR PAZ004.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...LA CORTE
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1103 PM CDT SAT MAR 23 2013
.UPDATE...
ISSUED AT 538 PM CDT SAT MAR 23 2013
MADE A FEW MINOR MODIFICATIONS TO THE GRIDS BUT DID NOT CHANGE A
WHILE LOT. SLOWED DOWN THE EXPANSION OF MEASURABLE SNOWFALL
POTENTIAL A COUPLE OF HOURS TONIGHT AND IF THE CURRENT TRENDS
CONTINUE MAY NEED TO BACK OFF A LITTLE MORE THROUGH THE OVERNIGHT
HOURS. ONE FEATURE NOTICEABLE ON THE RADAR IS THE MID LEVEL DRY
PUNCH MOVING TOWARDS INTERSTATE 29 WITH A SIGNIFICANT DECREASE
REFLECTIVITY OVER THE LAST HOUR. THIS DRY LAYER REALLY STARTS TO
SHUT DOWN SATURATION IN THE DENDRITIC LAYER AND SUGGESTS THAT
PRETTY MUCH ONLY LOCATIONS FROM ABOUT VERMILLION TO JACKSON SOUTH
WILL SEE ANY MEASURABLE SNOWFALL TONIGHT. NO INSTABILITY...NO
TROUGH OF WARM AIR ALOFT AND NO MID LEVEL FRONTAL FORCING PRETTY
MUCH JUST LEAVES UPPER LEVEL SUPPORT AND A MARGINALLY DEEP
DENDRITIC LAYER TO WORK WITH FOR SNOW PRODUCTION. THE LATEST
TRENDS FROM THE RAP AND NAM12 HINT AT THIS DRY LAYER SUPPRESSING
SNOW PRODUCTION WITH LITTLE OR NO ACCUMULATION WEST OF A YANKTON
TO IVANHOE MINNESOTA LINE. IF THESE TRENDS CAN BE TRUSTED MAY NEED
TO DECREASE SNOW AMOUNTS FURTHER ALONG AND WEST OF THIS LINE.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 341 PM CDT SAT MAR 23 2013
LIGHT SNOW SPREADING NORTHEAST OUT OF NEBRASKA THIS AFTERNOON. PLENTY
OF MOISTURE IN DENDRITIC LAYER WITH WEAK LIFT EXPECTED ACROSS THE
EASTERN CWA OVERNIGHT. MAIN FORCING WILL REMAIN WELL SOUTH OF
CWA...BUT WITH THE WEAK UNFOCUSED LIFT OVER CWA TONIGHT...EXPECT
LIGHT SNOW TO PERSIST MOST OF NIGHT AS IT SPREADS NORTHEAST. THE MAIN
AREA OF LIGHT SNOW WILL LIKELY BE EAST OF A YKN-BKX LINE WITH BEST
CHANCE FOR 1 TO 2 INCHES OF SNOW ACROSS NORTHWEST IOWA...WITH LESSER
AMOUNTS TO THE NORTH AND WEST. LIGHT SNOW WILL LINGER EAST OF I29
SUNDAY MORNING...AND THEN ROTATE BACK SOUTHWEST DURING THE AFTERNOON
AS WEAK INVERTED TROUGH ROTATES SOUTHWEST AS SECONDARY WEAK WAVE
DROPS SOUTH OUT OF NORTH DAKOTA. SO WILL KEEP POPS IN FORECAST WITH
LIKELY POPS ACROSS THE EAST. AMOUNTS WILL AGAIN BE LIGHT WITH MOST
AREAS LESS THAN 1 INCH OF SNOW ON SUNDAY. TEMPERATURES WILL REMAIN
WELL BELOW NORMAL ON SUNDAY WITH HIGHS SIMILAR TO TODAY. CLOUD COVER
SHOULD HELP HOLD TEMPERATURES UP TONIGHT.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 341 PM CDT SAT MAR 23 2013
AS THE UPPER LOW CONTINUES TO PUSH SOUTH ALONG WITH A WEAK
INVERTED TROUGH...LIGHT SNOW AND FLURRIES WILL CONTINUE THROUGH
SUNDAY NIGHT. LOW LEVEL LAPSE RATES REMAIN PRETTY STEEP...THUS COULD
SEE SOME BRIEFLY HEAVIER SNOW SHOWERS MIXED IN WITH THE LIGHTER
SNOW. OVERALL THOUGH NOT EXPECTING MUCH MORE THAN ABOUT AN INCH OF
ADDITIONAL ACCUMULATION. CLOUD COVER AND A BLUSTERY NORTHERLY WIND
WILL KEEP LOWS FROM FALLING TOO MUCH...GENERALLY THINKING LOWER 20S.
LIFT BECOMES EVEN WEAKER ON MONDAY...BUT ATMOSPHERE REMAINS NEARLY
SATURATED...THUS THINKING FLURRIES LINGER THROUGH THE DAY WITH ONLY
A DUSTING OR LESS EXPECTED. HIGHS WILL REMAIN WELL BELOW
NORMAL...UPPER 20S TO LOWER 30S. CLOUDS SLOWLY BEGIN TO DISSIPATE
MONDAY NIGHT FROM WEST TO EAST. LOWS A BIT TRICKY AND DEPENDENT ON
HOW FAST CLOUDS CLEAR AND WINDS DIE OFF...THUS WENT CLOSE TO
CONSENSUS FOR NOW UNTIL CLOUD COVER AND WINDS BECOME MORE
CERTAIN...GENERALLY IN THE TEENS.
WEAK RIDGING TRIES TO BUILD TUESDAY INTO THE END OF THE WORK WEEK.
THIS WILL RESULT IN WARMING...BUT STILL BELOW NORMAL...TEMPERATURES
EACH DAY...WITH HIGHS IN THE 40S TO AROUND 50 BY WEEKS END. OVERALL
PRECIP CHANCES LOOK PRETTY LOW THROUGH THE EXTENDED. WEAK WAVE ON
FRIDAY COULD BRING A LITTLE BIT OF LIGHT RAIN...BUT MODEL
DIFFERENCES AND INCONSISTENCY TOO BIG TO INCLUDE ANY POPS AT THIS
TIME. ANOTHER POTENTIAL WEAK NORTHERN STREAM WAVE MAY COME THROUGH
SATURDAY OR SATURDAY NIGHT WITH SOME LIGHT RAIN OR SNOW. SO OVERALL
MAYBE A FEW LIGHT PRECIPITATION CHANCES MID TO LATE NEXT WEEK...BUT
TIMING STILL UNCERTAIN. MODELS COMING INTO BETTER AGREEMENT THAT A
CLOSED UPPER LOW WILL COME INTO THE CALIFORNIA COAST ON SATURDAY
EVENTUALLY MOVING INTO THE PLAINS BY EARLY THE FOLLOWING WEEK. THIS
WOULD BE OUR NEXT CHANCE OF MORE SIGNIFICANT PRECIPITATION AMOUNTS.
THE UPPER AIR PATTERN MAY ONCE AGAIN FORCE THIS SYSTEM SOUTH...BUT
WE WILL HAVE TO MONITOR TRENDS OVER THE COMING WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1056 PM CDT SAT MAR 23 2013
DRY AIR CONTINUES TO WIN THE BATTLE AND VFR CONDITIONS HAVE
SETTLED WEST OF THE JAMES RIVER VALLEY. KHON IS RIGHT ON THE
EDGE...AND IS A TOUGH CALL WHETHER VFR OR MVFR CEILINGS WILL WIN
OUT. FURTHER TO THE EAST...MAINLY MVFR CONDITIONS WILL
PREVAIL...WITH LIGHT SNOW/FLURRIES DEVELOPING MAINLY ALONG AND
EAST OF I-29 THROUGHOUT THE DAY. IT IS DIFFICULT TO DEFINE WHEN
THE SNOW WILL END...BUT THE FURTHER NORTH...THE LESS RESTRICTION
TO VISIBILITY THAT IS EXPECTED.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...08
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
659 PM CDT SAT MAR 23 2013
.UPDATE...
ISSUED AT 538 PM CDT SAT MAR 23 2013
MADE A FEW MINOR MODIFICATIONS TO THE GRIDS BUT DID NOT CHANGE A
WHILE LOT. SLOWED DOWN THE EXPANSION OF MEASURABLE SNOWFALL
POTENTIAL A COUPLE OF HOURS TONIGHT AND IF THE CURRENT TRENDS
CONTINUE MAY NEED TO BACK OFF A LITTLE MORE THROUGH THE OVERNIGHT
HOURS. ONE FEATURE NOTICEABLE ON THE RADAR IS THE MID LEVEL DRY
PUNCH MOVING TOWARDS INTERSTATE 29 WITH A SIGNIFICANT DECREASE
REFLECTIVITY OVER THE LAST HOUR. THIS DRY LAYER REALLY STARTS TO
SHUT DOWN SATURATION IN THE DENDRITIC LAYER AND SUGGESTS THAT
PRETTY MUCH ONLY LOCATIONS FROM ABOUT VERMILLION TO JACKSON SOUTH
WILL SEE ANY MEASURABLE SNOWFALL TONIGHT. NO INSTABILITY...NO
TROUGH OF WARM AIR ALOFT AND NO MID LEVEL FRONTAL FORCING PRETTY
MUCH JUST LEAVES UPPER LEVEL SUPPORT AND A MARGINALLY DEEP
DENDRITIC LAYER TO WORK WITH FOR SNOW PRODUCTION. THE LATEST
TRENDS FROM THE RAP AND NAM12 HINT AT THIS DRY LAYER SUPPRESSING
SNOW PRODUCTION WITH LITTLE OR NO ACCUMULATION WEST OF A YANKTON
TO IVANHOE MINNESOTA LINE. IF THESE TRENDS CAN BE TRUSTED MAY NEED
TO DECREASE SNOW AMOUNTS FURTHER ALONG AND WEST OF THIS LINE.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 341 PM CDT SAT MAR 23 2013
LIGHT SNOW SPREADING NORTHEAST OUT OF NEBRASKA THIS AFTERNOON. PLENTY
OF MOISTURE IN DENDRITIC LAYER WITH WEAK LIFT EXPECTED ACROSS THE
EASTERN CWA OVERNIGHT. MAIN FORCING WILL REMAIN WELL SOUTH OF
CWA...BUT WITH THE WEAK UNFOCUSED LIFT OVER CWA TONIGHT...EXPECT
LIGHT SNOW TO PERSIST MOST OF NIGHT AS IT SPREADS NORTHEAST. THE MAIN
AREA OF LIGHT SNOW WILL LIKELY BE EAST OF A YKN-BKX LINE WITH BEST
CHANCE FOR 1 TO 2 INCHES OF SNOW ACROSS NORTHWEST IOWA...WITH LESSER
AMOUNTS TO THE NORTH AND WEST. LIGHT SNOW WILL LINGER EAST OF I29
SUNDAY MORNING...AND THEN ROTATE BACK SOUTHWEST DURING THE AFTERNOON
AS WEAK INVERTED TROUGH ROTATES SOUTHWEST AS SECONDARY WEAK WAVE
DROPS SOUTH OUT OF NORTH DAKOTA. SO WILL KEEP POPS IN FORECAST WITH
LIKELY POPS ACROSS THE EAST. AMOUNTS WILL AGAIN BE LIGHT WITH MOST
AREAS LESS THAN 1 INCH OF SNOW ON SUNDAY. TEMPERATURES WILL REMAIN
WELL BELOW NORMAL ON SUNDAY WITH HIGHS SIMILAR TO TODAY. CLOUD COVER
SHOULD HELP HOLD TEMPERATURES UP TONIGHT.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 341 PM CDT SAT MAR 23 2013
AS THE UPPER LOW CONTINUES TO PUSH SOUTH ALONG WITH A WEAK
INVERTED TROUGH...LIGHT SNOW AND FLURRIES WILL CONTINUE THROUGH
SUNDAY NIGHT. LOW LEVEL LAPSE RATES REMAIN PRETTY STEEP...THUS COULD
SEE SOME BRIEFLY HEAVIER SNOW SHOWERS MIXED IN WITH THE LIGHTER
SNOW. OVERALL THOUGH NOT EXPECTING MUCH MORE THAN ABOUT AN INCH OF
ADDITIONAL ACCUMULATION. CLOUD COVER AND A BLUSTERY NORTHERLY WIND
WILL KEEP LOWS FROM FALLING TOO MUCH...GENERALLY THINKING LOWER 20S.
LIFT BECOMES EVEN WEAKER ON MONDAY...BUT ATMOSPHERE REMAINS NEARLY
SATURATED...THUS THINKING FLURRIES LINGER THROUGH THE DAY WITH ONLY
A DUSTING OR LESS EXPECTED. HIGHS WILL REMAIN WELL BELOW
NORMAL...UPPER 20S TO LOWER 30S. CLOUDS SLOWLY BEGIN TO DISSIPATE
MONDAY NIGHT FROM WEST TO EAST. LOWS A BIT TRICKY AND DEPENDENT ON
HOW FAST CLOUDS CLEAR AND WINDS DIE OFF...THUS WENT CLOSE TO
CONSENSUS FOR NOW UNTIL CLOUD COVER AND WINDS BECOME MORE
CERTAIN...GENERALLY IN THE TEENS.
WEAK RIDGING TRIES TO BUILD TUESDAY INTO THE END OF THE WORK WEEK.
THIS WILL RESULT IN WARMING...BUT STILL BELOW NORMAL...TEMPERATURES
EACH DAY...WITH HIGHS IN THE 40S TO AROUND 50 BY WEEKS END. OVERALL
PRECIP CHANCES LOOK PRETTY LOW THROUGH THE EXTENDED. WEAK WAVE ON
FRIDAY COULD BRING A LITTLE BIT OF LIGHT RAIN...BUT MODEL
DIFFERENCES AND INCONSISTENCY TOO BIG TO INCLUDE ANY POPS AT THIS
TIME. ANOTHER POTENTIAL WEAK NORTHERN STREAM WAVE MAY COME THROUGH
SATURDAY OR SATURDAY NIGHT WITH SOME LIGHT RAIN OR SNOW. SO OVERALL
MAYBE A FEW LIGHT PRECIPITATION CHANCES MID TO LATE NEXT WEEK...BUT
TIMING STILL UNCERTAIN. MODELS COMING INTO BETTER AGREEMENT THAT A
CLOSED UPPER LOW WILL COME INTO THE CALIFORNIA COAST ON SATURDAY
EVENTUALLY MOVING INTO THE PLAINS BY EARLY THE FOLLOWING WEEK. THIS
WOULD BE OUR NEXT CHANCE OF MORE SIGNIFICANT PRECIPITATION AMOUNTS.
THE UPPER AIR PATTERN MAY ONCE AGAIN FORCE THIS SYSTEM SOUTH...BUT
WE WILL HAVE TO MONITOR TRENDS OVER THE COMING WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 647 PM CDT SAT MAR 23 2013
DRY AIR FILTERING IN FROM THE WEST HAS EFFECTIVELY CUT OFF
PRECIPITATION AT BOTH HURON AND SIOUX FALLS TERMINALS. EXPECT DRY
AIR TO RESULT IN RISING CEILINGS AT KHON...WHERE THE DRY AIR WILL
STRUGGLE TO GET THAT FAR EAST INTO KFSD TERMINAL. KSUX SHOULD SEE
LIGHT SNOW THROUGH MUCH OF TONIGHT INTO TOMORROW....SLOWLY
ACCUMULATING TO AN INCH OR TWO. MAINLY EXPECTING VISIBILITIES TO
HOVER IN THE 2 TO 4 MI RANGE.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...08
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
929 PM CDT SAT MAR 23 2013
.MESOSCALE UPDATE...
AT 915PM...RADAR INDICATED AREAS OF MODERATE RAIN ENTERING
SOUTHERN MIDDLE TN. 00Z SOUNDING ANALYSIS DOES SHOW A CONSIDERABLE
INVERSION AT THE 800 MB LEVEL WITH STEEP LAPSE RATES ABOVE THE
INVERSION. SHORT TERM MODELS VARY ON DEPICTING HOW TONIGHTS
ACTIVITY WILL EVOLVE.
THE NAM IS DEFINITELY THE MOST AGGRESSIVE WITH THUNDER
POSSIBILITIES...DEPICTING STRONG LOW TO MID LEVEL OMEGA FIELDS
DRAPED FROM WESTERN KY THROUGH NORTHEAST AL. THIS IN CONJUNTION
WITH AN INTENSIFYING LLJ OF 45-50 KTS OVER NORTHERN AL. STRONG
SPEED CONVERGENCE AT THE 850 MB LEVEL OVER SOUTH CENTRAL TN
APPEARS TO BE THE METHOD OF FORCING THAT COULD PRODUCE SOME STRONG
THUNDERSTORMS OVERNIGHT FOR AREAS IN THE SOUTHERN THIRD OF THE
CWA. SMALL HAIL AND SOME STRONG WINDS WOULD BE THE MAIN THREATS.
OTHER HI RESOLUTION MODELS...WHILE STILL BRINGING WIDESPREAD RAIN
THROUGH MIDDLE TN BY 08Z...ARE LESS ROBUST ON THE FORCING. WHILE
THE SFC LOW PASSES ACROSS CENTRAL AL...AND THE LLJ DOES
INTENSIFY...RUC/HRRR DEPICTS WEAKER
INSTABILITY...CONVERGENCE...AND BULK SHEAR. THUS RESULTING IN A
WIDESPREAD...AND HEAVY AT TIMES...RAIN EVENT.
IF STRONG STORMS WERE TO DEVELOP FOR MIDDLE TN...STILL BELIEVE THE
THREAT WOULD BE IN THE SOUTHERNMOST COUNTIES...BUT FOR NOW...FEEL
THE MODERATE TO HEAVY RAIN SCENARIO WITH SOME THUNDER POSSIBLE
WILL STILL BE VALID.
&&
.PREV DISCUSSION... /ISSUED 649 PM CDT SAT MAR 23 2013/
UPDATE...ADDED AVIATION SECTION FOR 00Z TAF`S.
AVIATION...BNA/CKV/CSV...CONDITIONS SLOWLY DETERIORATING ACROSS
MIDDLE TENNESSEE THIS EVENING AS A SURFACE LOW APPROACHES FROM
THE SW. LOOK FOR LIGHT RAIN DURING THE EVENING WITH CIGS
EVENTUALLY LOWERING BELOW 3 KFT. WINDS WILL REMAIN LIGHT
OVERNIGHT, EVEN AS SHOWERS INCREASE IN INTENSITY AND CIGS DROP TO
IFR. RUC SOUNDINGS SHOWING NO SURFACED-BASED OR ELEVATED
INSTABILITY, SO WILL LEAVE TS OUT OF THE TAF`S. EXPECT WINDS TO
SHIFT AROUND TO THE SW ON SUNDAY AND INCREASE DRAMATICALLY AS THE
LOW BISECTS THE MID STATE.
PREV DISCUSSION... /ISSUED 242 PM CDT SAT MAR 23 2013/
DISCUSSION...
SHOWERS AND A FEW THUNDERSTORMS HAVE SPREAD AS FAR EAST AS NORTH
MISSISSIPPI AND INTO THE FAR SOUTHWEST CORNER OF TENNESSEE AROUND
MEMPHIS. GULF COAST SYSTEM WILL WORK ALONG COAST TONIGHT WITH
INVERTED TROUGH EXTENDING UP INTO TENNESSEE THROUGH THE OVERNIGHT
AS LOW LIFTS NORTHWARD LATE NIGHT INTO NORTH ALABAMA BY 12Z
SUNDAY. IT LOOKS LIKE A PRETTY GOOD ROUND OF RAIN LIFTING NORTH
THROUGH ALABAMA AND INTO MIDDLE TENNESSEE AFTER MIDNIGHT. I EXPECT
TO HEAR A LITTLE THUNDER WITH GOOD DOWNPOURS WITH THIS IN THE LATE
NIGHT HOURS AS IT MOVES THROUGH THE AREA. SURFACE LOW LIFTS UP
INTO MIDDLE TENNESSEE DURING THE DAY SUNDAY SO AM EXPECTING MORE
RAIN WITH A FEW THUNDERSTORMS DURING THE DAY ON SUNDAY. SURFACE
LOW LIFTS OUT TO THE NORTHEAST AND INTO EASTERN KENTUCKY BY
MIDNIGHT SUNDAY NIGHT WHILE UNDERGOING CYCLOGENSIS WITH PRECIP
HANGING BACK OVER MIDDLE TENNESSEE AS A MIX OF RAIN AND SNOW
SUNDAY NIGHT AS TEMPS FALL INTO THE LOWER 30S MOST AREAS. ON
MONDAY PRECIP STILL LINGERING IN THE FORM OF A MIX OVER SOUTHWESTERLY
AREAS AND LIGHT SNOW NORTHEAST HALF WITH HIGHS MOSTLY IN THE UPPER
30S. MONDAY NIGHT LOOKS HAVE THE BEST CHANCE FOR SEEING A LITTLE
ACCUMULATION HERE IN THE MID STATE. I THINK WE COULD BE LOOKING AT
AN INCH IN FENTRESS AND CUMBERLAND COUNTIES WEST TOWARD PUTNAM
COUNTY AS RESIDUAL MOISTURE GETS SQUEEZED OUT WITH A LITTLE HELP
FROM OROGRAPHY. LOOKS LIKE TEMPS WILL BE BELOW NORMAL AT LEAST
THROUGH NEXT FRIDAY WITH HIGHS ON SATURDAY IN THE 60S WHICH IS
JUST ABOUT NORMAL FOR THIS TIME OF THE YEAR.
CLIMATE...TEMPS ARE AVERAGING NEARLY 4 DEGREES BELOW NORMAL SO FAR THIS
MARCH. WHAT A CONTRAST WITH MARCH OF 2012 WHICH WAS THE WARMEST MARCH
ON RECORD. RAINFALL HAS TOTALED 3.20 INCHES WHICH IS CLOSE TO NORMAL
THROUGH THE THIRD WEEK OF MARCH.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
TB12
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
649 PM CDT SAT MAR 23 2013
.UPDATE...ADDED AVIATION SECTION FOR 00Z TAF`S.
&&
.AVIATION...BNA/CKV/CSV...CONDITIONS SLOWLY DETERIORATING ACROSS
MIDDLE TENNESSEE THIS EVENING AS A SURFACE LOW APPROACHES FROM
THE SW. LOOK FOR LIGHT RAIN DURING THE EVENING WITH CIGS
EVENTUALLY LOWERING BELOW 3 KFT. WINDS WILL REMAIN LIGHT
OVERNIGHT, EVEN AS SHOWERS INCREASE IN INTENSITY AND CIGS DROP TO
IFR. RUC SOUNDINGS SHOWING NO SURFACED-BASED OR ELEVATED
INSTABILITY, SO WILL LEAVE TS OUT OF THE TAF`S. EXPECT WINDS TO
SHIFT AROUND TO THE SW ON SUNDAY AND INCREASE DRAMATICALLY AS THE
LOW BISECTS THE MID STATE.
&&
.PREV DISCUSSION... /ISSUED 242 PM CDT SAT MAR 23 2013/
DISCUSSION...
SHOWERS AND A FEW THUNDERSTORMS HAVE SPREAD AS FAR EAST AS NORTH
MISSISSIPPI AND INTO THE FAR SOUTHWEST CORNER OF TENNESSEE AROUND
MEMPHIS. GULF COAST SYSTEM WILL WORK ALONG COAST TONIGHT WITH
INVERTED TROUGH EXTENDING UP INTO TENNESSEE THROUGH THE OVERNIGHT
AS LOW LIFTS NORTHWARD LATE NIGHT INTO NORTH ALABAMA BY 12Z
SUNDAY. IT LOOKS LIKE A PRETTY GOOD ROUND OF RAIN LIFTING NORTH
THROUGH ALABAMA AND INTO MIDDLE TENNESSEE AFTER MIDNIGHT. I EXPECT
TO HEAR A LITTLE THUNDER WITH GOOD DOWNPOURS WITH THIS IN THE LATE
NIGHT HOURS AS IT MOVES THROUGH THE AREA. SURFACE LOW LIFTS UP
INTO MIDDLE TENNESSEE DURING THE DAY SUNDAY SO AM EXPECTING MORE
RAIN WITH A FEW THUNDERSTORMS DURING THE DAY ON SUNDAY. SURFACE
LOW LIFTS OUT TO THE NORTHEAST AND INTO EASTERN KENTUCKY BY
MIDNIGHT SUNDAY NIGHT WHILE UNDERGOING CYCLOGENSIS WITH PRECIP
HANGING BACK OVER MIDDLE TENNESSEE AS A MIX OF RAIN AND SNOW
SUNDAY NIGHT AS TEMPS FALL INTO THE LOWER 30S MOST AREAS. ON
MONDAY PRECIP STILL LINGERING IN THE FORM OF A MIX OVER SOUTHWESTERLY
AREAS AND LIGHT SNOW NORTHEAST HALF WITH HIGHS MOSTLY IN THE UPPER
30S. MONDAY NIGHT LOOKS HAVE THE BEST CHANCE FOR SEEING A LITTLE
ACCUMULATION HERE IN THE MID STATE. I THINK WE COULD BE LOOKING AT
AN INCH IN FENTRESS AND CUMBERLAND COUNTIES WEST TOWARD PUTNAM
COUNTY AS RESIDUAL MOISTURE GETS SQUEEZED OUT WITH A LITTLE HELP
FROM OROGRAPHY. LOOKS LIKE TEMPS WILL BE BELOW NORMAL AT LEAST
THROUGH NEXT FRIDAY WITH HIGHS ON SATURDAY IN THE 60S WHICH IS
JUST ABOUT NORMAL FOR THIS TIME OF THE YEAR.
CLIMATE...TEMPS ARE AVERAGING NEARLY 4 DEGREES BELOW NORMAL SO FAR THIS
MARCH. WHAT A CONTRAST WITH MARCH OF 2012 WHICH WAS THE WARMEST MARCH
ON RECORD. RAINFALL HAS TOTALED 3.20 INCHES WHICH IS CLOSE TO NORMAL
THROUGH THE THIRD WEEK OF MARCH.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
ROSE
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
103 PM CDT FRI MAR 22 2013
.DISCUSSION...
SEE AVIATION SECTION.
&&
.AVIATION...
THE LOW CLOUD FIELD ACROSS THE BIG COUNTRY WILL CONTINUE TO SLOWLY
ERODE THIS AFTERNOON. EXPECT SCATTERED COVERAGE AT KABI 21-23Z. COLD
FRONTAL BOUNDARY WILL WEAKEN THROUGH THE REMAINDER OF THIS AFTERNOON
AS IT DRIFTS SOUTH ACROSS THE INTERSTATE 10 CORRIDOR. THE FRONTAL
BOUNDARY SHOULD STALL NEAR OR JUST SOUTH OF THE SOUTHERN BORDER OF
OUR FORECAST/WARNING AREA THIS EVENING. THE FRONT WILL RETURN NORTH
AS A WARM FRONT TONIGHT...WITH WINDS BECOMING SOUTHEAST OVERNIGHT.
EXPECT LOW CLOUDS TO DEVELOP AND EXPAND WEST ACROSS PARTS OF OUR AREA
AFTER 06Z...AND CEILINGS TO BE IN THE 1K-2K FT RANGE. WINDS WILL VEER
TO SOUTH EARLY SATURDAY MORNING. PACIFIC FRONT/DRYLINE PASSAGE EXPECTED
IN THE 15Z-18Z TIME FRAME...FOLLOWED BY INCREASING AND GUSTY WEST WINDS.
THIS WILL ALSO QUICKLY SCOUR OUT THE LOW-LEVEL MOISTURE AND CLOUD COVER.
&&
.PREV DISCUSSION... /ISSUED 1124 AM CDT FRI MAR 22 2013/
UPDATE...
FORECAST HAS BEEN UPDATED MAINLY FOR TEMPERATURES TODAY...
SEE DISCUSSION.
DISCUSSION...
SURFACE COLD FRONT HAS PROGRESSED INTO OUR SOUTHERN COUNTIES LATE
THIS MORNING. AT 11 AM THE FRONT EXTENDED FROM JUST SOUTH OF MASON
TO JUST NORTH OF OZONA. THE LATEST RUC13 AND NAM12 MODELS HAVE THE
FRONT MOVING AT A MUCH SLOWER PACE THIS AFTERNOON ACROSS OUR
SOUTHERNMOST COUNTIES. THIS FRONT IS EXPECTED TO STALL NEAR OR JUST
SOUTH OF OUR FORECAST/WARNING AREA THIS EVENING. LOW CLOUD COVER HAS
DEVELOPED AND PERSISTED ACROSS THE BIG COUNTRY...AND WAS MORE
PATCHY ACROSS THE SOUTHERN HEARTLAND AND SOUTHERN CONCHO VALLEY.
THE COMBINATION OF COLD AIR ADVECTION AND CLOUD COVER HAS RESULTED
IN LITTLE TEMPERATURE RECOVERY ACROSS THE BIG COUNTRY. THE MODEL
LOW-LEVEL MOISTURE FIELDS INDICATE THAT THE SOUTHERN END OF THE LOW
CLOUD FIELD ACROSS THE BIG COUNTRY WILL SLOWLY ERODE THIS AFTERNOON...
BUT SHOULD REMAIN PERSISTENT ACROSS THE NORTHERNMOST COUNTIES. WITH
THE COLD AIR ADVECTION BEHIND THE FRONT A LITTLE STRONGER THAN
PREVIOUSLY ANTICIPATED...HAVE LOWERED TEMPERATURES THIS AFTERNOON
ACROSS OUR NORTHERN AND CENTRAL COUNTIES. TEMPERATURES STILL LOOK ON
TARGET ACROSS THE FAR SOUTHERN PART OF OUR AREA. SHOULD END UP WITH
ABOUT A 30 DEGREE NORTH-SOUTH TEMPERATURE GRADIENT ACROSS WEST CENTRAL
TEXAS WITH THE HIGHS THIS AFTERNOON. FORECAST PRODUCTS HAVE BEEN UPDATED.
PREV DISCUSSION... /ISSUED 612 AM CDT FRI MAR 22 2013/
DISCUSSION...
SEE AVIATION DISCUSSION BELOW.
AVIATION...
VFR OR MVFR FLYING CONDITIONS ARE EXPECTED ACROSS WEST CENTRAL
TEXAS THE NEXT 24 HOURS. A COLD FRONT WILL MOVE FROM NORTH TO
SOUTH THROUGH THE FORECAST AREA TODAY. ALTHOUGH NO RAIN IS
EXPECTED FROM THE FRONT SOME LOW CLOUDS ARE EXPECTED TO MOVE
THROUGH THE AREA WITH IT. CLOUD CEILINGS COULD BRIEFLY LOWER
AIRPORT WEATHER CONDITIONS TO MVFR WITH BROKEN CLOUD COVER
POSSIBLY BECOMING OVERCAST BELOW THREE THOUSAND FEET.
ON SATURDAY A PACIFIC FRONT WILL BREEZE THROUGH THE FORECAST AREA
FROM WEST TO EAST BRINGING BRISK WINDS OF 20 TO 25 MPH WITH
HIGHER GUST ACROSS THE AREA SATURDAY AFTERNOON. RELATIVE HUMIDITY
WILL PLUMMET INTO THE TEENS AND SINGLE DIGITS AND WILL CLEAR AWAY
MOST LOW CLOUDS ACROSS THE FORECAST AREA BY AFTERNOON.
A THIRD COLD WILL MOVE FROM NORTH TO SOUTH ACROSS THE FORECAST
AREA LATE SATURDAY NIGHT AND EARLY SUNDAY MORNING. BRISK 20 TO 25
MPH NORTH WINDS WILL ACCOMPANY THIS FRONT AND BRING SIGNIFICANTLY
COOLER MORNING TEMPERATURES ACROSS THE AREA WITH LOWS NEAR OR
SLIGHTLY BELOW FREEZING ON MONDAY AND ON TUESDAY MORNING.
PREV DISCUSSION... /ISSUED 415 AM CDT FRI MAR 22 2013/
SHORT TERM...
LIGHT SOUTH SOUTHWEST WINDS OF 10 TO 15KT WILL PREVAIL THROUGH DAWN
HOURS ACROSS WEST CENTRAL TEXAS. A WEAK SURFACE LOW PRESSURE AREA
ABOUT 50 MILES NORTHEAST OF THROCKMORTON COUNTY WILL MOVE EAST BY
EARLY MORNING HOURS AND A COLD FRONT WILL MOVE THROUGH THE AREA ON
FRIDAY. WINDS FROM THE NORTH AT 12 TO 18KT WITH SOME HIGHER GUSTS
WILL FOLLOW IMMEDIATELY BEHIND THE COLD FRONT THAT WILL BE
ACCOMPANIED BY SOME LOW CLOUDS. BY EARLY FRIDAY EVENING WINDS FROM
THE NORTH WILL WEAKEN TO 10 TO 15KT AND ANY LOW CLOUDS ASSOCIATED
WITH THE FRONT WILL MOVE EAST OUT OF THE FORECAST AREA. LIGHT 5 TO
10 KT EAST AND NORTHEAST WINDS WILL DOMINATE OVERNIGHT FRIDAY INTO
EARLY SATURDAY AND SOME LOW CLOUDS AND MOISTER AIR WILL RETURN FROM
THE EAST TO EASTERN AND CENTRAL COUNTIES.
A FIRE WEATHER WATCH HAS BEEN ISSUED FOR MOST OF WEST CENTRAL TEXAS
FROM NOON TO 7PM SATURDAY...IN ASSOCIATION WITH A PACIFIC COLD FRONT
THAT WILL BLAST EAST THROUGH THE AREA BEGINNING LATE SATURDAY
MORNING. AFTERNOON AND EARLY EVENING WINDS ON SATURDAY WILL BLOW
FROM THE WEST AT 18 TO 22KT WITH HIGHER GUSTS AND WILL BE
ACCOMPANIED BY VERY DRY AIR...RELATIVE HUMIDITY WILL DROP INTO THE
LOW TEENS AND SINGLE DIGITS. NEAR CRITICAL FIRE WEATHER CONDITIONS
ARE EXPECTED AND RED FLAG WARNINGS MAY BE NECESSARY FOR SOME
COUNTIES SATURDAY AFTERNOON AND EARLY SATURDAY EVENING...ESPECIALLY
ACROSS WEST AND SOUTHWEST COUNTIES.
LONG TERM...
A STRONG COLD FRONT WILL PUSH THROUGH WEST CENTRAL TEXAS SATURDAY
EVENING. COULD SEE NORTH WINDS SUSTAINED NEAR 30 MPH...WITH GUSTS
IN THE LOWER 40S FOR SEVERAL HOURS BEHIND THE FRONT. THE AIR WILL
BE QUITE DRY...AND FIRE WEATHER CONDITIONS WILL CONTINUE TO BE
ELEVATED. FIRE DEPARTMENTS WORKING ANY WILDFIRES EARLIER ON
SATURDAY SHOULD BE ALERT TO THE SUDDEN CHANGE IN WIND DIRECTION.
FREEZE POSSIBLE MONDAY AND TUESDAY MORNING AS THE 1030 MB SURFACE
HIGH PRESSURE...WITH ORIGINS IN WESTERN CANADA...BUILDS DIRECTLY
OVER THE REGION. A BIT TOO EARLY TO KNOW HOW COLD IT WILL BE.
MODELS ARE SUGGESTING A LIGHT FREEZE IN THE 30 TO 32 RANGE
MONDAY MORNING...WITH PERHAPS A DEGREE OR TWO LOWER TUESDAY MORNING (DUE
TO WEAKER WINDS). IN ANY CASE...WITH THE GROWING SEASON
STARTING...LOOK FOR POTENTIAL FREEZE WARNINGS ISSUED LATER THIS
WEEKEND...IF CONDITIONS CONTINUE TO WARRANT.
LOW LEVEL MOISTURE WILL FINALLY RETURN MIDWEEK. MODELS DO NOT
INDICATED MUCH LIFT AND MID LEVELS ARE DRY...SO WILL NOT BE
ADDING ANY RAINFALL CHANCES.
04
FIRE WEATHER...
ELEVATED TO FIRE WEATHER CONDITIONS WILL OCCUR FRIDAY FROM THE
COMBINATION OF BRISK NORTH WINDS AND DRY AIR BEHIND A COLD FRONT.
NEAR CRITICAL FIRE WEATHER IS EXPECTED MIDDAY TO EVENING HOURS ON
SATURDAY...A FIRE WEATHER WATCH HAS BEEN ISSUED FOR MOST OF WEST
CENTRAL TEXAS FROM NOON TO 7PM SATURDAY. RED FLAG WARNINGS MAY BE
NECESSARY...WEST AND SOUTHWEST COUNTIES WILL BE MOST THREATENED.
LYONS
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 55 49 79 33 55 / 5 10 10 5 5
SAN ANGELO 72 53 86 38 59 / 0 10 10 5 5
JUNCTION 85 55 87 40 63 / 0 10 10 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY
EVENING FOR THE FOLLOWING ZONES: CALLAHAN...COKE...COLEMAN...
CONCHO...CROCKETT...FISHER...HASKELL...IRION...JONES...KIMBLE...
MASON...MCCULLOCH...MENARD...NOLAN...RUNNELS...SCHLEICHER...
STERLING...SUTTON...TAYLOR...TOM GREEN.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
1124 AM CDT FRI MAR 22 2013
.UPDATE...
FORECAST HAS BEEN UPDATED MAINLY FOR TEMPERATURES TODAY...
SEE DISCUSSION.
&&
.DISCUSSION...
SURFACE COLD FRONT HAS PROGRESSED INTO OUR SOUTHERN COUNTIES LATE
THIS MORNING. AT 11 AM THE FRONT EXTENDED FROM JUST SOUTH OF MASON
TO JUST NORTH OF OZONA. THE LATEST RUC13 AND NAM12 MODELS HAVE THE
FRONT MOVING AT A MUCH SLOWER PACE THIS AFTERNOON ACROSS OUR
SOUTHERNMOST COUNTIES. THIS FRONT IS EXPECTED TO STALL NEAR OR JUST
SOUTH OF OUR FORECAST/WARNING AREA THIS EVENING. LOW CLOUD COVER HAS
DEVELOPED AND PERSISTED ACROSS THE BIG COUNTRY...AND WAS MORE
PATCHY ACROSS THE SOUTHERN HEARTLAND AND SOUTHERN CONCHO VALLEY.
THE COMBINATION OF COLD AIR ADVECTION AND CLOUD COVER HAS RESULTED
IN LITTLE TEMPERATURE RECOVERY ACROSS THE BIG COUNTRY. THE MODEL
LOW-LEVEL MOISTURE FIELDS INDICATE THAT THE SOUTHERN END OF THE LOW
CLOUD FIELD ACROSS THE BIG COUNTRY WILL SLOWLY ERODE THIS AFTERNOON...
BUT SHOULD REMAIN PERSISTENT ACROSS THE NORTHERNMOST COUNTIES. WITH
THE COLD AIR ADVECTION BEHIND THE FRONT A LITTLE STRONGER THAN
PREVIOUSLY ANTICIPATED...HAVE LOWERED TEMPERATURES THIS AFTERNOON
ACROSS OUR NORTHERN AND CENTRAL COUNTIES. TEMPERATURES STILL LOOK ON
TARGET ACROSS THE FAR SOUTHERN PART OF OUR AREA. SHOULD END UP WITH
ABOUT A 30 DEGREE NORTH-SOUTH TEMPERATURE GRADIENT ACROSS WEST CENTRAL
TEXAS WITH THE HIGHS THIS AFTERNOON. FORECAST PRODUCTS HAVE BEEN UPDATED.
&&
.PREV DISCUSSION... /ISSUED 612 AM CDT FRI MAR 22 2013/
DISCUSSION...
SEE AVIATION DISCUSSION BELOW.
AVIATION...
VFR OR MVFR FLYING CONDITIONS ARE EXPECTED ACROSS WEST CENTRAL
TEXAS THE NEXT 24 HOURS. A COLD FRONT WILL MOVE FROM NORTH TO
SOUTH THROUGH THE FORECAST AREA TODAY. ALTHOUGH NO RAIN IS
EXPECTED FROM THE FRONT SOME LOW CLOUDS ARE EXPECTED TO MOVE
THROUGH THE AREA WITH IT. CLOUD CEILINGS COULD BRIEFLY LOWER
AIRPORT WEATHER CONDITIONS TO MVFR WITH BROKEN CLOUD COVER
POSSIBLY BECOMING OVERCAST BELOW THREE THOUSAND FEET.
ON SATURDAY A PACIFIC FRONT WILL BREEZE THROUGH THE FORECAST AREA
FROM WEST TO EAST BRINGING BRISK WINDS OF 20 TO 25 MPH WITH
HIGHER GUST ACROSS THE AREA SATURDAY AFTERNOON. RELATIVE HUMIDITY
WILL PLUMMET INTO THE TEENS AND SINGLE DIGITS AND WILL CLEAR AWAY
MOST LOW CLOUDS ACROSS THE FORECAST AREA BY AFTERNOON.
A THIRD COLD WILL MOVE FROM NORTH TO SOUTH ACROSS THE FORECAST
AREA LATE SATURDAY NIGHT AND EARLY SUNDAY MORNING. BRISK 20 TO 25
MPH NORTH WINDS WILL ACCOMPANY THIS FRONT AND BRING SIGNIFICANTLY
COOLER MORNING TEMPERATURES ACROSS THE AREA WITH LOWS NEAR OR
SLIGHTLY BELOW FREEZING ON MONDAY AND ON TUESDAY MORNING.
PREV DISCUSSION... /ISSUED 415 AM CDT FRI MAR 22 2013/
SHORT TERM...
LIGHT SOUTH SOUTHWEST WINDS OF 10 TO 15KT WILL PREVAIL THROUGH DAWN
HOURS ACROSS WEST CENTRAL TEXAS. A WEAK SURFACE LOW PRESSURE AREA
ABOUT 50 MILES NORTHEAST OF THROCKMORTON COUNTY WILL MOVE EAST BY
EARLY MORNING HOURS AND A COLD FRONT WILL MOVE THROUGH THE AREA ON
FRIDAY. WINDS FROM THE NORTH AT 12 TO 18KT WITH SOME HIGHER GUSTS
WILL FOLLOW IMMEDIATELY BEHIND THE COLD FRONT THAT WILL BE
ACCOMPANIED BY SOME LOW CLOUDS. BY EARLY FRIDAY EVENING WINDS FROM
THE NORTH WILL WEAKEN TO 10 TO 15KT AND ANY LOW CLOUDS ASSOCIATED
WITH THE FRONT WILL MOVE EAST OUT OF THE FORECAST AREA. LIGHT 5 TO
10 KT EAST AND NORTHEAST WINDS WILL DOMINATE OVERNIGHT FRIDAY INTO
EARLY SATURDAY AND SOME LOW CLOUDS AND MOISTER AIR WILL RETURN FROM
THE EAST TO EASTERN AND CENTRAL COUNTIES.
A FIRE WEATHER WATCH HAS BEEN ISSUED FOR MOST OF WEST CENTRAL TEXAS
FROM NOON TO 7PM SATURDAY...IN ASSOCIATION WITH A PACIFIC COLD FRONT
THAT WILL BLAST EAST THROUGH THE AREA BEGINNING LATE SATURDAY
MORNING. AFTERNOON AND EARLY EVENING WINDS ON SATURDAY WILL BLOW
FROM THE WEST AT 18 TO 22KT WITH HIGHER GUSTS AND WILL BE
ACCOMPANIED BY VERY DRY AIR...RELATIVE HUMIDITY WILL DROP INTO THE
LOW TEENS AND SINGLE DIGITS. NEAR CRITICAL FIRE WEATHER CONDITIONS
ARE EXPECTED AND RED FLAG WARNINGS MAY BE NECESSARY FOR SOME
COUNTIES SATURDAY AFTERNOON AND EARLY SATURDAY EVENING...ESPECIALLY
ACROSS WEST AND SOUTHWEST COUNTIES.
LONG TERM...
A STRONG COLD FRONT WILL PUSH THROUGH WEST CENTRAL TEXAS SATURDAY
EVENING. COULD SEE NORTH WINDS SUSTAINED NEAR 30 MPH...WITH GUSTS
IN THE LOWER 40S FOR SEVERAL HOURS BEHIND THE FRONT. THE AIR WILL
BE QUITE DRY...AND FIRE WEATHER CONDITIONS WILL CONTINUE TO BE
ELEVATED. FIRE DEPARTMENTS WORKING ANY WILDFIRES EARLIER ON
SATURDAY SHOULD BE ALERT TO THE SUDDEN CHANGE IN WIND DIRECTION.
FREEZE POSSIBLE MONDAY AND TUESDAY MORNING AS THE 1030 MB SURFACE
HIGH PRESSURE...WITH ORIGINS IN WESTERN CANADA...BUILDS DIRECTLY
OVER THE REGION. A BIT TOO EARLY TO KNOW HOW COLD IT WILL BE.
MODELS ARE SUGGESTING A LIGHT FREEZE IN THE 30 TO 32 RANGE
MONDAY MORNING...WITH PERHAPS A DEGREE OR TWO LOWER TUESDAY MORNING (DUE
TO WEAKER WINDS). IN ANY CASE...WITH THE GROWING SEASON
STARTING...LOOK FOR POTENTIAL FREEZE WARNINGS ISSUED LATER THIS
WEEKEND...IF CONDITIONS CONTINUE TO WARRANT.
LOW LEVEL MOISTURE WILL FINALLY RETURN MIDWEEK. MODELS DO NOT
INDICATED MUCH LIFT AND MID LEVELS ARE DRY...SO WILL NOT BE
ADDING ANY RAINFALL CHANCES.
04
FIRE WEATHER...
ELEVATED TO FIRE WEATHER CONDITIONS WILL OCCUR FRIDAY FROM THE
COMBINATION OF BRISK NORTH WINDS AND DRY AIR BEHIND A COLD FRONT.
NEAR CRITICAL FIRE WEATHER IS EXPECTED MIDDAY TO EVENING HOURS ON
SATURDAY...A FIRE WEATHER WATCH HAS BEEN ISSUED FOR MOST OF WEST
CENTRAL TEXAS FROM NOON TO 7PM SATURDAY. RED FLAG WARNINGS MAY BE
NECESSARY...WEST AND SOUTHWEST COUNTIES WILL BE MOST THREATENED.
LYONS
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 55 49 79 34 55 / 5 10 10 5 5
SAN ANGELO 72 53 86 38 59 / 0 10 10 5 5
JUNCTION 85 55 87 43 63 / 0 10 10 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY
EVENING FOR THE FOLLOWING ZONES: CALLAHAN...COKE...COLEMAN...
CONCHO...CROCKETT...FISHER...HASKELL...IRION...JONES...KIMBLE...
MASON...MCCULLOCH...MENARD...NOLAN...RUNNELS...SCHLEICHER...
STERLING...SUTTON...TAYLOR...TOM GREEN.
&&
$$
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1137 PM CDT THU MAR 21 2013
.AVIATION...
MVFR CIGS MOVING NORTH FROM THE GULF NOW AND ARE ALMOST AT TAF
SITES...SO WILL START 06Z TAFS WITH MVFR. HAVE BACKED UP
METROPLEX FROPA A BIT BASED ON NAM/RAP GUIDANCE...AND STILL FEEL
CLOUDS WILL BE VERY SLOW TO BREAK FRIDAY AFTERNOON. WHEN THEY
DO...CLEAR SKIES NORTH OF THE FRONT WITH LIGHT NORTHEAST FLOW
WILL ALLOW TEMPERATURES TO COOL TO SATURATION LATE FRIDAY NIGHT
AND HAVE INCLUDED IFR CIG/VSBY IN THE EXTENDED PORTION OF DFW
TAF. ALL TAF SITES WILL LIKELY BE IFR BEFORE SUNRISE SATURDAY
WITH WIDESPREAD FOG IN THE AREA. 84
&&
.UPDATE...
WEAK MOISTURE CONVERGENCE AND LIMITED INSTABILITY PREVENTED
THUNDERSTORM DEVELOPMENT ALONG THE DRY LINE THIS AFTERNOON/EARLY
THIS EVENING. NOW WITH THE LOSS OF SURFACE HEATING...STORM CHANCES
ALONG THE DRY LINE HAVE DECREASED SIGNIFICANTLY. THERE IS STILL A
CHANCE OF SOME ELEVATED SHOWERS AND THUNDERSTORMS ACROSS THE
NORTHERN HALF OF NORTH TEXAS WITH THE BEST STORM CHANCES ACROSS
THE NORTHEAST ZONES JUST NORTH OF A WARM FRONT. FURTHER
SOUTH...SOME WARM AIR ADVECTION SHOWERS ARE POSSIBLE...ESPECIALLY
TOWARD MORNING.
FOR THIS UPDATE...WE WILL LOWER EVENING POPS IN ALL ZONES AND MAKE
SOME MINOR WIND/CLOUD COVER AND HOURLY TEMP/DEW POINT ADJUSTMENTS.
79
&&
.PREV DISCUSSION... /ISSUED 319 PM CDT THU MAR 21 2013/
BREEZY AND MOSTLY CLOUDY CONDITIONS CONTINUE ACROSS THE REGION
THIS EVENING BUT SOME CHANGES ARE STILL EXPECTED BY THE LATE
AFTERNOON AND EVENING HOURS. THE SURFACE LOW REMAINS OVER THE
TEXAS PANHANDLE WITH THE LEADING EDGE OF THE DRYLINE NOW LOCATED
ROUGHLY ALONG A LINE FROM VERNON TO SAN ANGELO. DEWPOINTS CONTINUE
TO INCREASE INTO THE LOWER 50S AHEAD OF THE DRYLINE BUT
INSTABILITY IS STILL LACKING. SATELLITE IMAGERY DEPICTS EVIDENCE
OF INCREASING LIFT APPROACHING THE REGION FROM THE WEST. SOME LOW
LEVEL CUMULUS HAS NOW DEVELOPED IN NORTHWEST TEXAS AND SOUTHWEST
OKLAHOMA AND MID LEVEL CLOUDS OVER WEST CENTRAL TEXAS ARE
LOOKING MORE ROBUST. INITIATION IS STILL POSSIBLE NEAR THE DRYLINE
LATE THIS AFTERNOON...AMONGST BREAKS IN THE MID LEVEL CLOUD DECK
BUT THE WINDOW FOR SEVERE POTENTIAL IS DECREASING. INITIATION NEAR
THE DRYLINE JUST WEST OF OUR CWA LIKELY WILL NOT BE UNTIL AFTER 5
PM AND THE SEVERE THREAT WILL BE DIMINISHING WITH THE LOSS OF
HEATING BY 8-9 PM. CONSIDERING THE LATEST TRENDS...WITH THE MID
LEVEL CLOUD COVER THAT IS STRETCHING BACK WEST...SBCAPES NEAR 1000
J/KG AS PREVIOUSLY PREDICTED MAY BE TOO HIGH AND VALUES WILL
REMAIN CLOSER TO 500-800 J/KG. CONVERGENCE ALONG THE DRYLINE IS
NOT VERY GOOD AT THIS TIME AS THE WINDS AHEAD OF THE DRYLINE ARE
ALSO FROM THE SOUTHWEST. THE RAP SHOWS THE SURFACE LOW REMAINING
IN THE TEXAS PANHANDLE FOR THE NEXT FEW HOURS WHICH MEANS THE SURFACE
WINDS WILL LIKELY NOT HAVE A CHANCE TO BACK AS THE DRYLINE MOVES
CLOSER. HOWEVER...WITH STRONG SHEAR...LIFT FROM A SERIES OF
SHORTWAVES MOVING NEAR THE REGION AND THE POTENTIAL FOR INCREASING
INSTABILITY OVER THE NEXT FEW HOURS...STILL EXPECT TO SEE A FEW
THUNDERSTORMS OVER OUR NORTHWESTERN COUNTIES WITH A FEW STRONG TO
SEVERE STORMS POSSIBLE. ANY STORMS THAT DO DEVELOP WILL LIKELY
MOVE EAST OR SOUTHEAST. LARGE HAIL AND DAMAGING WINDS WILL BE THE
MAIN THREATS.
EXPECT THE THUNDERSTORM ACTIVITY TO WANE FAIRLY QUICKLY AROUND OR
AFTER SUNSET BUT ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE OVER THE NORTHERN HALF OF THE REGION OVERNIGHT. THE
HIGHEST CHANCES FOR RAIN CONTINUE TO BE OVER THE NORTHEASTERN
COUNTIES. CANNOT RULE OUT A STRONG STORM OR TWO PRODUCING SMALL
HAIL AND/OR GUSTY WINDS BUT THE INSTABILITY OVERNIGHT IS FAIRLY
WEAK. A COLD FRONT WILL MOVE INTO THE REGION LATE TONIGHT AND
CONTINUE TO PROGRESS SOUTH THROUGH THE DAY TOMORROW. THERE
CONTINUES TO BE A CHANCE FOR RAIN AND ISOLATED THUNDERSTORMS OVER
THE EASTERN HALF OF THE REGION TOMORROW. WE COULD SEE A STRONG
STORM OR TWO OVER OUR FAR SOUTHEASTERN COUNTIES TOMORROW AFTERNOON
AHEAD OF THE FRONT.
THE FRONT WILL STALL JUST SOUTH OF THE CWA FRIDAY NIGHT AND THEN
RETREAT NORTH AS A WARM FRONT ON SATURDAY. AS THE WARM FRONT LIFTS
NORTH...WARM AIR ADVECTION OVER THE COOL SURFACE LAYER WILL RESULT
IN SCATTERED RAIN ACTIVITY THROUGHOUT THE DAY WITH ISOLATED
THUNDERSTORMS POSSIBLE. HIGHEST RAIN CHANCES WILL BE OVER THE
EASTERN HALF OF THE REGION. A STRONGER COLD FRONT WILL PUSH ACROSS
THE REGION SATURDAY NIGHT. THE RAIN WILL BE ENDING FROM WEST TO
EAST DURING THE DAY AS A DRYLINE MOVES ACROSS THE REGION. MUCH
COOLER AND DRIER AIR WILL SETTLE INTO THE REGION FOR SEVERAL DAYS
WITH TEMPERATURES FALLING BELOW NORMAL FOR AT LEAST THE FIRST HALF
OF NEXT WEEK. A FREEZE IS NOT EXPECTED REGION-WIDE ON ANY GIVEN
NIGHT BUT NEAR FREEZING TEMPERATURES WILL BE POSSIBLE MAINLY OVER
THE NORTHWESTERN HALF OF THE CWA SUNDAY AND MONDAY NIGHTS. TEMPERATURES
WILL START TO WARM LATER IN THE WEEK AND THE GFS IS MUCH FASTER TO
WARM TEMPERATURES THAN THE ECMWF.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 57 64 47 68 42 / 20 20 20 50 10
WACO, TX 62 71 50 74 42 / 10 20 20 50 5
PARIS, TX 48 58 45 58 37 / 50 30 20 50 20
DENTON, TX 51 60 45 65 39 / 30 20 20 40 10
MCKINNEY, TX 54 60 45 62 40 / 40 20 20 50 10
DALLAS, TX 58 64 48 68 43 / 20 20 20 50 10
TERRELL, TX 58 64 48 65 42 / 30 30 20 50 10
CORSICANA, TX 62 71 50 69 43 / 20 20 20 50 10
TEMPLE, TX 62 76 52 76 41 / 10 20 20 40 5
MINERAL WELLS, TX 50 63 46 74 39 / 20 10 20 30 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
559 PM CDT FRI MAR 22 2013
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
310 PM CDT FRI MAR 22 2013
THE FORECAST IS FOCUSED ON THE LATE WEEKEND PRECIPITATION CHANCES
ACROSS PARTS OF THE AREA.
AS OF THIS AFTERNOON...WATER VAPOR LOOP OVERLAID WITH RAP 500MB
HEIGHT FIELDS SHOWS WEAK RIDGING MOVING ACROSS THE UPPER MIDWEST
WITH ANOTHER DIGGING NEGATIVELY TITLED SHORTWAVE TROUGH ACROSS THE
NORTHERN ROCKIES. THERE ARE FEW EMBEDDED VORTICITY IMPULSES IN
THAT FLOW...WHICH ARE THE PLAYERS FOR THE WEEKEND STORM SYSTEM. AT
THE SURFACE...HIGH PRESSURE RIDGE AXIS REMAINS SQUEEZED OVER THE
UPPER MIDWEST AND 24-HR PRESSURE/TEMPERATURE CHANGES ARE MINIMAL.
JUST A UPWARD NUDGE COMPARED TO YESTERDAY.
QUIET CONDITIONS LOOK TO PREVAIL INTO SATURDAY AS WEAK UPPER RIDGING
BUILDS INTO THE AREA DOWNSTREAM OF THE DEVELOPING TROUGH TO THE
WEST. ANOTHER CHILLY NIGHT ON TAP...THOUGH NOT AS COLD AS RECENT
NIGHTS AS THE AIRMASS CONTINUES TO BE MODIFIED. CLOUD TRENDS HAVE
BEEN TRICKY AS DRIER AIRMASS AS OBSERVED BY 22.12Z MPX/GRB/DVN
SOUNDINGS IS ERODING ANY EASTWARD PROGRESS OF HIGH LEVEL CLOUDS.
HAVE KEPT MOSTLY CLEAR SKIES AT LEAST THROUGH 03-06Z FOR MUCH OF
THE AREA. HOWEVER...500-700MB WARM AIR ADVECTION SATURDAY SHOULD BE
ENOUGH TO SPREAD MID/HIGH CLOUDS ACROSS THE AREA FROM THE SOUTHWEST.
HIGHS WERE NUDGED DOWN A FEW DEGREES TO REMOVE SOME OF THE LATE
MARCH CLIMATOLOGY BIAS...BUT LOW TO MID 30S STILL LOOK REASONABLE.
THE WEEKEND STORM SYSTEM THAT YESTERDAY WAS AIMING TO TRACK SOUTH
HAS NOW BECOME SLIGHTLY MORE INTERESTING FOR PARTS OF THE FORECAST
AREA AS THERE HAS BEEN A SHIFT BACK TO THE NORTH. OVERALL...THE MID
TO UPPER LEVEL SUPPORT HAS IMPROVED THANKS TO A STRONGER NORTHERN
STREAM SHORTWAVE...AND SOME IMPRESSIVE LIFT DYNAMICS. ALTHOUGH THE
BULK OF THE FORCING DOES REMAIN TO OUR SOUTH...THERE ARE A FEW
THINGS TO BE NOTED. FIRST...THE AREA IS FAVORABLY LOCATED IN THE
LEFT EXIT REGION OF THE 250MB JET PROVIDING DECENT DIVERGENCE ALOFT.
AS THE SYSTEM EJECTS INTO THE CENTRAL PLAINS AND MID MISSISSIPPI
RIVER VALLEY...BROAD BUT VERY PERSISTENT 280-290K ISENTROPIC LIFT IS
PRESENT SOUTH OF I-90 AND THERE IS A 6 TO 12 HOUR TIME FRAME SUNDAY
MORNING AND AFTERNOON WITH DECENT MID LEVEL WARM AIR ADVECTION. VERY
WEAK 700MB FRONTOGENESIS IS SEEN ACROSS NORTHEAST IOWA AND FAR
SOUTHERN WISCONSIN AS WELL. FINALLY...THE MODEL GUIDANCE SHOWS A
BRIEF PERIOD OF 500-300MB PV ADVECTION. ALL OF THE ABOVE POINT TO A
PERIOD OF LIGHT BUT ACCUMULATING SNOW...HOWEVER...THE BIGGEST
NEGATIVELY COMPETING FACTOR WILL BE THE STRONG NORTHEASTERLY FEED OF
VERY DRY AIR RESULTING IN SATURATION ISSUES...ESPECIALLY IN THE
AREAS WHERE THE FORCING IS GREATEST. THE SATURATION PROBLEMS WILL
EVAPORATE A LOT OF PRECIPITATION EARLY ON...LIMITING POTENTIAL
ACCUMULATIONS.
REGARDING POTENTIAL SNOWFALL AMOUNTS...MODEL GUIDANCE CAME IN WITH
MORE QPF...WITH THE 22.09Z SREF PLUMES SHOWING A MEAN OF 4 INCHES AT
KDBQ. THE SPREAD VARIES FROM SEVERAL MEMBERS AT ONLY AT A
TRACE...THEN A FEW GREATER THAN 8 INCHES. THAT TREND IS SEEN ACROSS
THE AREA...BUT TO A LESSER DEGREE AT KDEH...KLSE...KRST. COBB OUTPUT
FROM 22.12Z NAM VARIED FROM LESS THAN AN INCH ALONG I-90...TO AROUND
6 INCHES AT KDBQ...AND 4 TO 5 INCHES AT KMCW AND KALO. HOWEVER...NOT
CONFIDENT ENOUGH TO MOVE COMPLETELY IN THAT DIRECTION GIVEN
AFOREMENTIONED DRY AIR / SATURATION ISSUES. ATTEMPTED TO CUT MODEL
QPF BY 1/3 TO ACCOUNT FOR THIS AND THIS TRANSLATES INTO AROUND 2
INCHES POSSIBLE ACROSS NORTHEAST IOWA AND FAR SOUTHWEST
WISCONSIN...THEN A TRACE TO MAYBE 1 INCH ALONG THE I-90 CORRIDOR
FROM PRE-SUNRISE SUNDAY THROUGH SUNDAY NIGHT.
IN SHORT...CONFIDENCE IN LIGHT BUT ACCUMULATING SNOWFALL SUNDAY /
SUNDAY EVENING HAS GROWN FOR THE SOUTHERN PORTIONS OF THE AREA WITH
FLURRIES OR OCCASIONAL LIGHT SNOW FOR ALONG AND JUST SOUTH OF I-90.
HAVE INCREASED PRECIPITATION CHANCES FOR THESE AREAS.
.LONG TERM...MONDAY THROUGH FRIDAY
310 PM CDT FRI MAR 22 2013
IN THE WAKE OF THE SUNDAY/SUNDAY NIGHT STORM SYSTEM...A REINFORCING
SHOT OF COLDER AIR LOOKS TO FOLLOW FOR MONDAY INTO MUCH OF NEXT
WEEK. CLIMATE PREDICTION CENTER FORECASTS THE ATLANTIC OSCILLATION
TO REMAIN NEGATIVE THROUGH AT LEAST APRIL 1ST...WHICH SUPPORTS OUR
STRETCH OF UNSEASONABLY COLD TEMPERATURES. THE LATEST CFS
TEMPERATURE ANOMALIES SHOW BELOW NORMAL TEMPERATURES EVEN INTO MID
APRIL POSSIBLY. LONGWAVE TROUGHING CONTINUES ACROSS THE EASTERN HALF
OF THE CONUS...WITH A WESTERN UPPER LEVEL RIDGE DEVELOPING BY THE
END OF NEXT WEEK. 850MB STANDARDIZED ANOMALIES VARY FROM -0.5 TO
-1.5 EACH DAY NEXT WEEK...GIVING HIGHS IN THE LOWER TO MID 30S AND
OVERNIGHT LOWS IN THE TEENS. TO HELP TREND THE FORECAST
BETTER...HAVE COOLED HIGHS/LOWS EACH DAY TO REMOVE CLIMATOLOGY BIAS
IN THE MODEL CONSENSUS THAT IS BEING INTRODUCED. THE THEME OF DRY
BUT COLD CONTINUES...WITH NO STORM SYSTEMS ON THE HORIZON UNTIL NEXT
WEEKEND POSSIBLY.
&&
.AVIATION...TONIGHT AND SATURDAY
559 PM CDT FRI MAR 22 2013
A RIDGE OF HIGH PRESSURE OVER THE TAF SITES IS FORECAST TO BREAK
DOWN OVER THE NEXT 24 HOURS AS LOW PRESSURE DEVELOPS OVER THE
CENTRAL PLAINS. AS THIS OCCURS...NORTHEAST FLOW WILL VERY SLOWLY
DEVELOP IN THE LOWER LEVELS OF THE ATMOSPHERE. LOOKING TO THE
NORTHEAST...THERE IS A MVFR-VFR STRATUS ACROSS FAR NORTHEAST
WISCONSIN INTO UPPER MICHIGAN. WITH WINDS BASICALLY LIGHT AND
VARIABLE TONIGHT...ANTICIPATING THAT THIS STRATUS DECK WILL NOT
MOVE MUCH. A BETTER SHOT OF THE STRATUS MOVING TOWARDS THE TAF
SITES COMES TOMORROW AS THE NORTHEAST WIND PICKS UP. EVEN
THEN...DAYTIME HEATING SHOULD BE ENOUGH TO MIX THE STRATUS DECK TO
A VFR CEILING AT BOTH TAF SITES. OTHERWISE...SOME ALTOSTRATUS WILL
GRADUALLY SPREAD ACROSS THE TAF SITES DURING THE NEXT 24
HOURS...WELL AHEAD OF THE DEVELOPING STORM SYSTEM. THIS
ALTOSTRATUS IS ALREADY APPROACHING KRST THIS EVENING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
310 PM CDT FRI MAR 22 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...ZT
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
310 PM CDT FRI MAR 22 2013
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
310 PM CDT FRI MAR 22 2013
THE FORECAST IS FOCUSED ON THE LATE WEEKEND PRECIPITATION CHANCES
ACROSS PARTS OF THE AREA.
AS OF THIS AFTERNOON...WATER VAPOR LOOP OVERLAID WITH RAP 500MB
HEIGHT FIELDS SHOWS WEAK RIDGING MOVING ACROSS THE UPPER MIDWEST
WITH ANOTHER DIGGING NEGATIVELY TITLED SHORTWAVE TROUGH ACROSS THE
NORTHERN ROCKIES. THERE ARE FEW EMBEDDED VORTICITY IMPLUSES IN
THAT FLOW...WHICH ARE THE PLAYERS FOR THE WEEKEND STORM SYSTEM. AT
THE SURFACE...HIGH PRESSURE RIDGE AXIS REMAINS SQUEEZED OVER THE
UPPER MIDWEST AND 24-HR PRESSURE/TEMPERATURE CHANGES ARE MINIMAL.
JUST A UPWARD NUDGE COMPARED TO YESTERDAY.
QUIET CONDITIONS LOOK TO PREVAIL INTO SATURDAY AS WEAK UPPER RIDGING
BUILDS INTO THE AREA DOWNSTREAM OF THE DEVELOPING TROUGH TO THE
WEST. ANOTHER CHILLY NIGHT ON TAP...THOUGH NOT AS COLD AS RECENT
NIGHTS AS THE AIRMASS CONTINUES TO BE MODIFIED. CLOUD TRENDS HAVE
BEEN TRICKY AS DRIER AIRMASS AS OBSERVED BY 22.12Z MPX/GRB/DVN
SOUNDINGS IS ERODING ANY EASTWARD PROGRESS OF HIGH LEVEL CLOUDS.
HAVE KEPT MOSTLY CLEAR SKIES AT LEAST THROUGH 03-06Z FOR MUCH OF
THE AREA. HOWEVER...500-700MB WARM AIR ADVECTION SATURDAY SHOULD BE
ENOUGH TO SPREAD MID/HIGH CLOUDS ACROSS THE AREA FROM THE SOUTHWEST.
HIGHS WERE NUDGED DOWN A FEW DEGREES TO REMOVE SOME OF THE LATE
MARCH CLIMATOLOGY BIAS...BUT LOW TO MID 30S STILL LOOK REASONABLE.
THE WEEKEND STORM SYSTEM THAT YESTERDAY WAS AIMING TO TRACK SOUTH
HAS NOW BECOME SLIGHTLY MORE INTERESTING FOR PARTS OF THE FORECAST
AREA AS THERE HAS BEEN A SHIFT BACK TO THE NORTH. OVERALL...THE MID
TO UPPER LEVEL SUPPORT HAS IMPROVED THANKS TO A STRONGER NORTHERN
STREAM SHORTWAVE...AND SOME IMPRESSIVE LIFT DYNAMICS. ALTHOUGH THE
BULK OF THE FORCING DOES REMAIN TO OUR SOUTH...THERE ARE A FEW
THINGS TO BE NOTED. FIRST...THE AREA IS FAVORABLY LOCATED IN THE
LEFT EXIT REGION OF THE 250MB JET PROVIDING DECENT DIVERGENCE ALOFT.
AS THE SYSTEM EJECTS INTO THE CENTRAL PLAINS AND MID MISSISSIPPI
RIVER VALLEY...BROAD BUT VERY PERSISTENT 280-290K ISENTROPIC LIFT IS
PRESENT SOUTH OF I-90 AND THERE IS A 6 TO 12 HOUR TIME FRAME SUNDAY
MORNING AND AFTERNOON WITH DECENT MID LEVEL WARM AIR ADVECTION. VERY
WEAK 700MB FRONTOGENESIS IS SEEN ACROSS NORTHEAST IOWA AND FAR
SOUTHERN WISCONSIN AS WELL. FINALLY...THE MODEL GUIDANCE SHOWS A
BRIEF PERIOD OF 500-300MB PV ADVECTION. ALL OF THE ABOVE POINT TO A
PERIOD OF LIGHT BUT ACCUMULATING SNOW...HOWEVER...THE BIGGEST
NEGATIVELY COMPETING FACTOR WILL BE THE STRONG NORTHEASTERLY FEED OF
VERY DRY AIR RESULTING IN SATURATION ISSUES...ESPECIALLY IN THE
AREAS WHERE THE FORCING IS GREATEST. THE SATURATION PROBLEMS WILL
EVAPORATE A LOT OF PRECIPITATION EARLY ON...LIMITING POTENTIAL
ACCUMULATIONS.
REGARDING POTENTIAL SNOWFALL AMOUNTS...MODEL GUIDANCE CAME IN WITH
MORE QPF...WITH THE 22.09Z SREF PLUMES SHOWING A MEAN OF 4 INCHES AT
KDBQ. THE SPREAD VARIES FROM SEVERAL MEMBERS AT ONLY AT A
TRACE...THEN A FEW GREATER THAN 8 INCHES. THAT TREND IS SEEN ACROSS
THE AREA...BUT TO A LESSER DEGREE AT KDEH...KLSE...KRST. COBB OUTPUT
FROM 22.12Z NAM VARIED FROM LESS THAN AN INCH ALONG I-90...TO AROUND
6 INCHES AT KDBQ...AND 4 TO 5 INCHES AT KMCW AND KALO. HOWEVER...NOT
CONFIDENT ENOUGH TO MOVE COMPLETELY IN THAT DIRECTION GIVEN
AFOREMENTIONED DRY AIR / SATURATION ISSUES. ATTEMPTED TO CUT MODEL
QPF BY 1/3 TO ACCOUNT FOR THIS AND THIS TRANSLATES INTO AROUND 2
INCHES POSSIBLE ACROSS NORTHEAST IOWA AND FAR SOUTHWEST
WISCONSIN...THEN A TRACE TO MAYBE 1 INCH ALONG THE I-90 CORRIDOR
FROM PRE-SUNRISE SUNDAY THROUGH SUNDAY NIGHT.
IN SHORT...CONFIDENCE IN LIGHT BUT ACCUMULATING SNOWFALL SUNDAY /
SUNDAY EVENING HAS GROWN FOR THE SOUTHERN PORTIONS OF THE AREA WITH
FLURRIES OR OCCASIONAL LIGHT SNOW FOR ALONG AND JUST SOUTH OF I-90.
HAVE INCREASED PRECIPITATION CHANCES FOR THESE AREAS.
.LONG TERM...MONDAY THROUGH FRIDAY
310 PM CDT FRI MAR 22 2013
IN THE WAKE OF THE SUNDAY/SUNDAY NIGHT STORM SYSTEM...A REINFORCING
SHOT OF COLDER AIR LOOKS TO FOLLOW FOR MONDAY INTO MUCH OF NEXT
WEEK. CLIMATE PREDICTION CENTER FORECASTS THE ATLANTIC OSCILLATION
TO REMAIN NEGATIVE THROUGH AT LEAST APRIL 1ST...WHICH SUPPORTS OUR
STRETCH OF UNSEASONABLY COLD TEMPERATURES. THE LATEST CFS
TEMPERATURE ANOMALIES SHOW BELOW NORMAL TEMPERATURES EVEN INTO MID
APRIL POSSIBLY. LONGWAVE TROUGHING CONTINUES ACROSS THE EASTERN HALF
OF THE CONUS...WITH A WESTERN UPPER LEVEL RIDGE DEVELOPING BY THE
END OF NEXT WEEK. 850MB STANDARDIZED ANOMALIES VARY FROM -0.5 TO
-1.5 EACH DAY NEXT WEEK...GIVING HIGHS IN THE LOWER TO MID 30S AND
OVERNIGHT LOWS IN THE TEENS. TO HELP TREND THE FORECAST
BETTER...HAVE COOLED HIGHS/LOWS EACH DAY TO REMOVE CLIMATOLOGY BIAS
IN THE MODEL CONSENSUS THAT IS BEING INTRODUCED. THE THEME OF DRY
BUT COLD CONTINUES...WITH NO STORM SYSTEMS ON THE HORIZON UNTIL NEXT
WEEKEND POSSIBLY.
&&
.AVIATION...THROUGH 18Z SATURDAY
1253 PM CDT FRI MAR 22 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. HIGH
PRESSURE WILL REMAIN OVER THE UPPER MISSISSIPPI RIVER VALLEY
THROUGH SATURDAY AFTERNOON PROVIDING QUIET WEATHER. CIRRUS IS
EXPECTED TO SPREAD FROM WEST TO EAST ACROSS THE AREA LATE THIS
EVENING THROUGH THE OVERNIGHT HOURS AS A TROUGH MOVES INTO THE
CENTRAL PLAINS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
310 PM CDT FRI MAR 22 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...ZT
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1148 PM CDT SAT MAR 23 2013
.DISCUSSION...
ISSUED 907 PM CDT SAT MAR 23 2013
WHILE THINGS WILL BE MOSTLY QUIET FOR THE NEXT SEVERAL HOURS
ACROSS CENTRAL AND SOUTHEAST ILLINOIS...A SIGNIFICANT EARLY SPRING
STORM IS STILL ON TRACK TO IMPACT THE AREA STARTING LATE TONIGHT
AND THROUGHOUT SUNDAY.
IT IS APPARENT THROUGH SURFACE OBS/SATELLITE LOOPS/00Z KILX
SOUNDING THAT THE LOCAL AIRMASS IS STILL PRETTY DRY AND WILL NEED
TO UNDERGO QUITE A BIT OF MOISTENING FOR SIGNIFICANT PRECIPITATION
TO OCCUR. A DRY NORTHEASTERLY FLOW FROM 800 MB TO THE SURFACE
SHOULD ALSO HELP TO LIMIT THE PRECIPITATION THREAT FOR A TIME. IN
ADDITION...THE UPPER LOW DRIVING THE STORM HAS ONLY RECENTLY
STOPPED DIGGING ACROSS THE SOUTHERN PLAINS...PER WATER VAPOR
LOOPS...AND IT WILL STILL TAKE SOME TIME TO GET HERE.
THE BULK OF THE FORECAST MODELS SUGGEST INCREASING WAA/ISENTROPIC
LIFT THROUGH THE NIGHT WILL HELP TO PROVIDE TOP DOWN MOISTENING...
ALLOWING MOST AREAS TO SEE LIGHT PRECIPITATION BY DAYBREAK SUNDAY.
HOWEVER...THE LATEST RUNS OF THE SHORT RANGE/HIGH RESOLUTION HRRR
AND RAP MODELS SUGGEST MUCH OF THE PRECIPITATION FALLING THROUGH
THE NIGHT WILL SIMPLY MOISTEN THE DRY AIR AND PRODUCE FAIRLY
MINIMAL PRECIPITATION AT THE SURFACE. THE HEAVIER SNOWFALL IS
STILL NOT EXPECTED TO ARRIVE UNTIL VERY LATE SUNDAY MORNING AND
THROUGH THE AFTERNOON.
THE LOW LEVEL THERMAL PROFILE IN THE 00Z KILX AND FORECAST
SOUNDINGS SUGGEST ENOUGH LOW LEVEL WARM AIR IN PLACE FOR THE
PRECIP TO START AS RAIN IN MANY AREAS. THE EVAPORATIVE COOLING DUE
TO THE DRY AIR/CONTINUED DRY LOW LEVEL FLOW SHOULD QUICKLY CHANGE
THE PRECIP OVER TO SNOW.
MOST OF FORECAST IS IN PRETTY GOOD SHAPE. HOWEVER...PLAN TO BACK
OFF ON POPS/PCPN AMOUNT A BIT TONIGHT BASED ON THE FACTORS
MENTIONED ABOVE. WILL NOT MAKE ANY HEADLINE ADJUSTMENTS AT THIS
TIME.
BAK
&&
.AVIATION...
ISSUED 1148 PM CDT SAT MAR 23 2013
PRECIPITATION BEGINNING TO BREAK OUT ACROSS CENTRAL ILLINOIS...
AND THIS TREND SHOULD SEE CONDITIONS DEGRADING TO IFR
OVERNIGHT/EARLY SUNDAY AS A STRONG STORM SYSTEM SPREADS SNOW INTO
THE REGION FROM THE SOUTHWEST. THERE WILL BE TWO HEAVIER WAVES OF
SNOWFALL...THE FIRST SHOULD OCCUR A FEW HOURS EITHER SIDE OF
SUNRISE SUNDAY...WITH THE SECOND OCCURRING SUNDAY AFTERNOON. WHILE
THERE MAY BE A BREAK LATER SUNDAY MORNING WHERE CONDITIONS BRIEFLY
IMPROVE ABOVE IFR...BUT CONFIDENCE IN THE DETAILS IS NOT HIGH.
NORTHEAST WINDS WILL PREVAIL THROUGH THE PERIOD AS THE TERMINALS
LIE TO THE NORTH/WEST OF THE MAIN STORM TRACK. EXPECT WINDS TO
BECOME QUITE GUSTY AT TIMES DURING THE DAY SUNDAY WHICH IS LIKELY
TO COINCIDE WITH THE HEAVIEST SNOWFALL AND RESULT IN THE LOWEST
VISIBILITIES.
BAK
&&
.PREV DISCUSSION...
ISSUED 255 PM CDT SAT MAR 23 2013
SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
THREAT FOR HEAVY WET SNOW OVER PORTIONS OF CENTRAL...EAST CENTRAL
AND SOUTHEAST ILLINOIS CONTINUES FOR SUNDAY THROUGH SUNDAY NIGHT.
MAJOR SPRING SNOW EVENT STARTING TO TAKE SHAPE OVER THE SOUTHERN
ROCKIES THIS AFTERNOON WITH PRECIP ALREADY BLOSSOMING WEST OF THE
MISSOURI RIVER IN THE MID LEVEL WARM ADVECTION/ISENTROPIC LIFT
REGION. AS THE AREA OF ENHANCED LIFT SHIFTS ENE INTO THE MIDWEST
LATER THIS EVENING...WE SHOULD SEE SOME RAIN AND SNOW DEVELOP TO
THE WEST OF THE MISSISSIPPI RIVER AND SPREAD EAST INTO WEST CENTRAL
ILLINOIS LATER THIS EVENING AND THEN SLOWLY TO THE EAST BY SUNDAY
MORNING. NAM-WRF CONTINUING TO DEPICT TWO SIGNIFICANT AREAS OF
LIFT WITH THIS STORM. THE INITIAL BAND OF LIFT/ISENT ASCENT PUSHES
ACRS THE AREA IN THE 06Z-15Z TIME FRAME...WITH A LULL IN THE MORE
INTENSE SNOWFALL AND THEN PICK UP AGAIN WITH THE SECOND AND MORE
CONCENTRATED AREA OF FORCING ASSOCIATED WITH THE CLOSED 500 MB LOW.
CROSS SECTIONS THROUGH THE HEART OF OUR CWA SHOWING THESE TWO DISTINCT
AREAS OF LIFT WELL WITH BOTH ASSOCIATED WITH DEEP MOISTURE AND
CONCENTRATED OMEGA IN THE FAVORED DENDRITIC ZONE. AS THE DEFORMATION
ZONE TRACKS ACRS THE REGION TOMORROW AFTERNOON AND EVENING ASSOCIATED
WITH THE MORE POTENT FORCING...THERE ARE A FEW AREAS OF NEGATIVE
EPV SHOWING UP ON THE CROSS SECTIONS JUST NORTH OF STL ENE TO JUST
SOUTH OF ROUTE 36 OVER CENTRAL IL. FORECAST SOUNDINGS ALSO SHOWING
A SMALL AREA OF MOST UNSTABLE CAPES IN THAT CORRIDOR AS WELL SUGGESTING
A CONTINUING THREAT FOR ISOLATED CONVECTION ASSOCIATED WITH THE HEAVIER
BURSTS OF SNOW. TROWAL SIGNATURE SHOWING UP ON THE 305K PRESSURE SURFACE
AS WELL SUNDAY EVENING WHICH WILL PROLONG THE SNOW EVENT ACROSS THE
EAST WITH ADDITIONAL ACCUMULATIONS POSSIBLE. NOT MUCH OF A THREAT FOR
BLOWING SNOW SUNDAY WITH SFC TEMPS AT OR ABOVE FREEZING...BUT THAT MAY
BE A DIFFERENT STORY SUNDAY NIGHT AS GUSTY NORTH TO NORTHWEST WINDS
AND COLDER TEMPERATURES BRING ABOUT AT LEAST A THREAT FOR SOME BLOWING
SNOW...ESP ACROSS THE NORTH AND EASTERN COUNTIES.
AS A RESULT...HAVE UPGRADED THE WATCH TO A WARNING FOR ALL AREAS EXCPT
ALONG AND NW OF THE ILLINOIS RIVER. HAD INITIALLY THOUGHT OF GOING
WITH AN ADVISORY FOR OUR SOUTHEAST COUNTIES...BUT BASED ON THE TRACK
OF THE CLOSED 850 AND 500 MB LOWS ON THE NAM-WRF AND SREF...THOUGHT
THE THREAT FOR ISOLD THUNDER SNOW...JUST NORTH OF THE RAIN-SNOW LINE...
WOULD BE ENHANCED. SO BUMPED UP THE SNOW NUMBERS IN SE IL WITH AMOUNTS
IN THE 5 TO 7 INCH RANGE. CARRIED THE WARNING INTO MONDAY MORNING ACRS
EAST CENTRAL IL BASED ON THE SLOWER TREND SHOWING UP ON MODELS THE PAST
FEW RUNS.
CYCLONIC FLOW IN THE WAKE OF THE DEPARTING STORM ON MONDAY AND MONDAY
NIGHT WILL YIELD SCATTERED SNOW SHOWERS OR FLURRIES ALONG WITH A
CONTINUATION OF THE UNSEASONABLY COLD TEMPERATURES FOR THE THIRD WEEK
OF MARCH.
LONG TERM...TUESDAY THROUGH SATURDAY...
THE CHILLY WEATHER WILL CONTINUE INTO TUESDAY AS THE UPPER LOW
SHIFTS TO THE EAST COAST...WITH 850 MB TEMPS LINGERING AROUND -10C.
HOWEVER...THE SECOND HALF OF THE WEEK WILL FEATURE SOME GRADUALLY
MODERATING AIR AS RIDGING SLOWLY BUILDS OVER THE WESTERN HALF OF THE
NATION. HIGHS CLOSER TO NORMAL FOR THIS TIME OF YEAR... I.E. 50S...
EXPECTED BY FRIDAY AND SATURDAY.
AFTER A SURFACE HIGH PRESSURE RIDGE SLOWLY MOVES THROUGH THE MIDWEST
WEDNESDAY AND WEDNESDAY NIGHT...NEXT FOCUS REMAINS WITH A SHORTWAVE
PASSING THROUGH LATE WEEK. LATEST ECMWF IS QUITE BULLISH WITH THE
PRECIP FRIDAY AND FRIDAY NIGHT...WHEREAS THE GFS IS ABOUT 12-18
HOURS FASTER WITH THIS. HAVE CONCENTRATED THE PRECIP CHANCES IN THE
GRIDS IN THE FRIDAY NIGHT TIME FRAME...ALTHOUGH CONFIDENCE IS NOT
ESPECIALLY HIGH AT THE MOMENT.
SHORT TERM...SMITH
LONG TERM....GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 1 AM CDT MONDAY FOR ILZ037-040>042-
047>054-061-066-071.
WINTER STORM WARNING FROM 4 AM SUNDAY TO 7 AM CDT MONDAY FOR
ILZ038-043>046-055>057-062-063-067-068-072-073.
WINTER WEATHER ADVISORY UNTIL 1 AM CDT MONDAY FOR ILZ027>029-036.
WINTER WEATHER ADVISORY FROM 4 AM SUNDAY TO 7 AM CDT MONDAY FOR
ILZ030-031.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
348 AM CDT SUN MAR 24 2013
.SYNOPSIS...
ISSUED AT 322 AM CDT SUN MAR 24 2013
06Z SFC ANALYSIS HAS THE LOW IN NORTHERN MISSISSIPPI WITH AN
INVERTED TROF INTO MISSOURI. ANOTHER TROF RAN FROM EASTERN MINNESOTA
INTO EASTERN IOWA. DEW POINTS WERE IN THE TEENS AND 20S OVER THE
GREAT LAKES AND MID MISSISSIPPI VALLEY WITH 30S AND HIGHER FROM THE
OHIO VALLEY ON SOUTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 322 AM CDT SUN MAR 24 2013
OVERALL AN INTERESTING SYSTEM. THE TRENDS OF BRINGING THE SYSTEM
NORTH HAVE ENDED UP BEING INCORRECT WITH THE MAIN LOW PASSING WELL
SOUTH OF THE AREA.
SATELLITE/RADAR SHOWS A BREAK IN THE SNOW ACROSS NORTHERN MISSOURI
BUT RAP TRENDS AND RECENT WATER VAPOR TRENDS INDICATE THIS BREAK IN
THE SNOW IS FILLING. THE WAA TOOL INDICATES THE BETTER SNOW WILL BE
ACROSS THE SOUTH IN THE HEADLINE AREA. HOWEVER...TEMPERATURES AT OR
JUST BELOW FREEZING IS ALLOWING SOME MELTING TO OCCUR WITH
ACCUMULATIONS BEING ON ELEVATED SURFACES. PAVEMENT TEMPERATURES ARE
AT OR ABOVE FREEZING SO MELTING IS OCCURRING THERE AS WELL.
SO...WILL CONTINUE WITH THE CURRENT HEADLINES AS IS. THE HWY 20
CORRIDOR HAS NOT YET SEEN ANY SNOW BUT THAT SHOULD CHANGE THIS
MORNING AS THE NEXT ROUND OF FORCING MOVES INTO THE AREA. INDIRECT
SOLAR INSOLATION WILL HELP PUSH TEMPERATURES ABOVE FREEZING DURING
THE DAY SO ADDITIONAL MELTING AND COMPACTION WILL OCCUR.
THE FURTHER SOUTH PASSAGE OF THE SYSTEM AND WARM TEMPERATURES WILL
HELP SUPPRESS OVERALL SNOWFALL AMOUNTS. IN THE ADVISORY AREA THE
EXTREME SOUTH PART OF THE CWFA SHOULD SEE 3-4 INCHES BY EVENING WITH
1-2 BY THE TIME ONE REACHES THE I-80 CORRIDOR. NORTH OF HWY 30
AMOUNTS SHOULD BE APPROACHING AN INCH.
TONIGHT...LIGHT SNOW WILL CONTINUE WITH IT ENDING ACROSS THE
NORTHERN THIRD OF THE CWFA AFTER MIDNIGHT. SOUTH OF A KOTM TO KGBG
LINE AMOUNTS AROUND OR JUST OVER AN INCH ARE EXPECTED WITH NOT QUITE
AN INCH AROUND THE I-80 CORRIDOR. NORTH OF HWY 30 A DUSTING TO ONE
HALF INCH IS EXPECTED. ..08..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 322 AM CDT SUN MAR 24 2013
LIGHT SNOW TO EXIT FAR SOUTHERN COUNTIES MON AM WITH PASSAGE
OF ELONGATED WEST-EAST UPPER TROUGH ON BACKSIDE OF OHIO VLY
SHORTWAVE. FEW FLURRIES MAY LINGER ACROSS ENTIRE AREA MON
WITH CYCLONIC FLOW AND COLD ADVECTION. 925 MB TEMPS AROUND
-5C SUPPORTS HIGHS MAINLY IN THE MIDDLE 30S. MON NGT... WITH
CONTINUED COLD ADVECTION AND CYCLONIC FLOW EXPECT PARTLY TO
MOSTLY CLOUDY SKIES AND THUS STAYED NEAR OR JUST ABOVE WARM
SIDE OF GUIDANCE ON LOWS. HOWEVER... AS CLOUDS GO SO GO THE
LOW TEMPS AND WILL NEED TO WATCH FOR POSSIBLY MORE CLEARING
AND COLDER LOWS WITH SOME SUGGESTION OF WEAK MID/UPPER LEVEL
RIDGING IN WAKE OF UPPER TROUGH.
TUE-TUE NGT... CYCLONIC FLOW TO KEEP AT LEAST PARTLY CLOUDY
SKIES TUE ESPECIALLY EASTERN 1/3-1/2... WITH ONLY SLIGHT
MODERATION ON TEMPS BY 1-3 DEGS FROM THOSE OF MON. CANT RULE
OUT FEW FLURRIES OR EVEN BRIEF SNOW SHOWER FAR EAST WITH
ENOUGH HEATING AS MODELS DEPICT WEAK ENERGY ROTATING DOWN
THROUGH WI AND NORTHERN IL TUE PM. PARTLY CLOUDY TO MOSTLY
CLEAR SKIES EXPECTED TUE NGT WITH SFC RIDGE AXIS BUILDING IN.
LOWS MAINLY UPPER TEENS TO LOWER 20S... BUT IF WINDS SHOULD
GO LIGHT FOR ANY LENGTH OF TIME THEN COULD SEE MINS AS COLD AS
AROUND 14-17 DEGS ESPECIALLY WEST/SOUTHWEST SECTIONS BEING IN
CLOSE PROXIMITY TO RIDGE AXIS.
WED-SAT... OVERALL MODERATING TEMPS LOOK TO BE IN STORE DURING
THE PERIOD... WITH TEMPS EDGING NEAR NORMAL TOWARD THE
END OF PERIOD AS THE PERSISTENT BLOCKING PATTERN OVER NORTH
AMERICA RESPONSIBLE FOR LOCKING IN THE COLD AIR IS SHOWN
TO BREAK DOWN. WITH THIS WARMING TREND WILL ALSO COME AT LEAST
SOME THREAT OF MAINLY LIGHT PRECIPITATION OVER THE LATTER HALF OF
THE WEEK BEING IN FAIRLY CLOSE PROXIMITY TO MID LEVEL BAROCLINIC
ZONE AND SUBJECT TO WEAK IMPULSES PROPAGATING DOWN IN NORTHWEST
FLOW ALOFT. CONSENSUS MODEL INTRODUCED SEVERAL PERIODS OF SLIGHT
CHC POPS FROM WED NGT THROUGH FRI... BUT GIVEN THE WEAK AND
VARYING SIGNAL FROM THE MODELS IT WAS COLLABORATED WITH
SURROUNDING OFFICES TO LOWER PRECIPITATION CHANCES BELOW MENTION
THROUGH FRI AND AWAIT FOR SOME BETTER CONSISTENCY. THE SIGNAL IS
STRONGER AND MORE CONSISTENT BY NEXT WEEKEND AND HAVE THEREFORE
LEFT IN PRECIPITATION CHCS BY SAT NGT. BEYOND THE SCOPE OF THE
EXTENDED... THE PATTERN REMAINS QUITE ACTIVE WITH THE MEDIUM RANGE
MODELS POINTING TO ANOTHER STORM SYSTEM POSSIBLY IMPACTING THE
AREA TOWARD THE MIDDLE PORTION OF THE FIRST WEEK OF APRIL WITH THE
POTENTIAL FOR AT LEAST MODERATE PRECIPITATION AMOUNTS WITH MAINLY
RAIN AND POSSIBLY SOME SNOW SUGGESTED. 05
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 322 AM CDT SUN MAR 24 2013
MVFR TO IFR CONDITIONS WILL PERSIST ACROSS EASTERN IOWA AND NORTHERN
ILLINOIS THROUGH 00Z/25. BRIEF PERIODS OF LIFR WILL ALSO BE
POSSIBLE...ESPECIALLY AT KBRL. AFT 00Z/25 CONDITIONS SHOULD SLOWLY
IMPROVE TO MVFR. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR
IAZ087>089-098-099.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ025-
026-034-035.
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MOZ009-
010.
&&
$$
SHORT TERM...08
LONG TERM...05
AVIATION...08
AREA FORECAST DISCUSSION...UPDATED
NWS DES MOINES IA
1151 PM CDT SAT MAR 23 2013
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TONIGHT/...
SYSTEM CONTINUES TO DIG SOUTHWARD THROUGH THE FRONT RANGE THIS
AFTERNOON WITH WIDESPREAD SNOWFALL ACROSS THE PLAINS. RECENTLY...
PRECIPITATION HAS BEEN EXPANDING FROM EASTERN KANSAS INTO WESTERN
MISSOURI IN WARM ADVECTION AIR OF THE SYSTEM. SOME MID TO HIGH
CLOUDINESS HAS SPREAD ACRS IOWA ALTHOUGH LOW LEVEL DRY AIR CONTINUES
TO MOVE IN FROM THE NORTHEAST. RECENT MODEL OUTPUT FROM THE 12Z GFS
PLUS THE HOURLY UPDATES FROM THE RAP CONTINUE TO INDICATE LATER
ONSET FOR MUCH OF THE FORECAST AREAS TONIGHT. THE NAM HAS BEEN MOST
AGGRESSIVE IN SPREADING SNOW INTO THE STATE THIS EVENING BUT SEEMS
TO BE THE ODD MODEL OUT AT THIS POINT WITH 18Z RUN BACKING OFF THE
MORE PROGRESSIVE 12Z RUN. HAVE GENERALLY STALLED THE ONSET OF
PRECIPITATION ACRS CENTRAL IOWA UNTIL LATER EVENING AND ACROSS THE
NORTH UNTIL WELL AFTER MIDNIGHT. NEWEST 18Z RAP WOULD NOT EVEN
BRING SNOW INTO DES MOINES UNTIL NEARLY 12Z ON SUNDAY AND REMAINS
DRY NORTH OF HIGHWAY 30.
ALL MODELS ALSO HAVE A BAND OF SNOW ACROSS NORTHWEST IOWA TONIGHT IN
A BAND OF WEAKER FORCING AHEAD OF UPPER CUTOFF CURRENTLY IN THE
DAKOTAS. ALREADY SOME LIGHT SNOW REPORTED IN SIOUX CITY AND HAVE
MAINTAINED THE POPS IN THE FAR WEST AND NORTHWEST FOR THIS AXIS OF
PRECIPITATION OVERNIGHT. ADVISORY WILL REMAIN INTACT FOR CURRENTLY
LOCATIONS ALTHOUGH HEAVIEST SNOWFALL APPEARS TO BE PRIMARILY IN THE
FAR SOUTHEAST OVERNIGHT WHERE AROUND 2 TO POSSIBLY 3 INCHES IS
EXPECTED. DES MOINES METRO MAY SEE AN INCH OR SO WITH LIGHT AMOUNTS
TOWARD THE NORTH.
.LONG TERM /SUNDAY THROUGH SATURDAY/...
MAIN FORECAST CONCERN WILL BE WITH PRECIPITATION CHANCES FOR
SUNDAY AND MONDAY. EXPECT WIDESPREAD SNOW TO BE ONGOING AT
BEGINNING OF PERIOD...ESPECIALLY ACROSS THE SOUTH AS LOW PRESSURE
SYSTEM PUSHES EAST ACROSS MISSOURI. SOUNDINGS AND CROSS SECTIONS
INDICATE GOOD SATURATION AND FORCING...ESPECIALLY ACROSS THE
SOUTH. FORCING BECOMES MUCH WEAKER FURTHER NORTH AWAY FROM THE
LOW...BUT ENOUGH TO RESULT IN AT LEAST LIGHT SNOWFALL THROUGHOUT
THE DAY MONDAY. BEST FORCING WILL BE EARLY...BEFORE 18Z AND EXPECT
TO SEE BEST SNOWFALL RATES THEN. BEST FORCING IS ABOVE THE
DENDRITIC LAYER...AND DO NOT ANTICIPATE SNOWFALL RATIOS TO BE MUCH
HIGHER THAN 10/1. DRY AIR WILL BEGIN TO PUSH BACK IN BEHIND SYSTEM
OVERNIGHT MONDAY...WITH PRECIPITATION ENDING ACROSS THE NE.
HOWEVER...GOOD VORT MAX PUSHING AROUND LOW WILL KEEP LINGERING
SNOW CHANCES ACROSS THE SW...BUT AGAIN WITH WEAKER FORCING ONLY
LIGHT SNOW EXPECTED. LINGERING LOW LEVEL SATURATION WILL ALLOW FOR
LINGERING LIGHT SNOW AND FLURRIES THROUGH MONDAY WITH COLD SURFACE
TEMPERATURES. SYSTEM WILL CONTINUE TO PULL EAST...AND MAY SEE
ADDITIONAL LINGERING FLURRIES THROUGH TUESDAY. TOTAL ACCUMULATIONS
ARE SIMILAR TO GOING WITH HIGHER TOTALS ACROSS THE SOUTH. WINDS WILL
BE STRONG BEHIND LOW...BUT WILL GENERALLY STAY BELOW 30MPH AND
WILL LEAD TO SOME IMPACTS...MOSTLY WITH ROADS AND REDUCED
VISIBILITIES....BUT DO NOT ANTICIPATE SIGNIFICANT IMPACTS WITH
SNOWFALL. GIVEN DURATION OF SNOWFALL...ADVISORY SEEMS WARRANTED
AND WILL LEAVE AS IS. HOWEVER...MAY NEED TO BE EXTENDED IN TIME
ACROSS THE SOUTH FOR LINGER SNOWFALL INTO MONDAY NIGHT...BUT WILL
LEAVE FOR FUTURE UPDATES AS MODELS CONTINUE TO VARY ON PLACEMENT
OF LOW.
TEMPERATURES WILL BEGIN TO WARM BY MID WEEK WITH SOUTHERLY SURFACE
FLOW AND INCREASING WAA. MODELS BRING ANOTHER LOW PRESSURE SYSTEM
ACROSS CANADA...WITH TRAILING FRONTAL BOUNDARY ACROSS MIDWEST.
THIS WILL BE FOCUS FOR PRECIPITATION CHANCES THROUGH THE WEEKEND.
HOWEVER...WITH WARMER TEMPERATURES PRECIPITATION LIKELY RAIN.
STILL SOME UNCERTAINTY IN TIMING AND LOCATION OF RAIN...AND HAVE
LEFT SLIGHT CHANCES FOR NOW.
&&
.AVIATION...24/06Z
SNOW HAS BEEN SLOW TO SPREAD NORTHWARD...BUT CONTINUES TO AFFECT
KDSM/KOTM AT THIS TIME. UPSTREAM RADAR AND SFC OBS INDICATE A 2 TO 3
HR GAP IN THE SNOW APPROACHING FROM THE SW...AND HAVE ATTEMPTED TO
TIME THIS GAP AT KDSM/KOTM WITH SNOW SPREADING INTO THE REMAINING
TERMINALS WITH THE SECOND BATCH MORE TOWARD 12Z. HOWEVER...THE
TIMING OF ONSET AT ALL TERMINALS REMAINS SOMEWHAT UNCERTAIN AND
AMENDMENTS WILL PROBABLY BE NECESSARY. IN THE MORE MODERATE
SNOWFALL...MAINLY AT KDSM/KOTM...IFR AND LOWER CONDITIONS WILL BE
MORE LIKELY WITH MVFR MORE LIKELY FURTHER NORTH. CONDITIONS WILL NOT
IMPROVE SUBSTANTIALLY ON SUNDAY...AND WILL PROBABLY DETERIORATE
AGAIN WITH BR DEVELOPMENT AFTER DARK ON SUNDAY NIGHT.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM CDT
SUNDAY FOR ADAIR-ADAMS-APPANOOSE-CASS-CLARKE-DAVIS-DECATUR-LUCAS-
MADISON-MAHASKA-MARION-MONROE-RINGGOLD-TAYLOR-UNION-WAPELLO-
WARREN-WAYNE.
&&
$$
SHORT TERM...COGIL
LONG TERM...AWB
AVIATION...LEE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
503 AM EDT SUN MAR 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 502 AM EDT SUN MAR 24 2013
WV IMAGERY AND RUC ANALYSIS INDICATED PERSISTENT HIGH LATITUDE
MID/UPPER LEVEL RIDGING FROM SCANDINAVIA INTO NORTHERN CANADA
RESULTING IN LOWER HEIGHTS AND COLDER AIR TO THE SOUTH ACROSS SRN
CANADA AND THE NRN CONUS. A WEAK RIDGE EXTENDED ACROSS THE WRN
GREAT LAKES BTWN MID LEVEL LOWS OVER THE DAKOTAS AND CANADIAN
MARATIMES. AT THE SFC...WEAK NE FLOW PREVAILED BETWEEN HIGH PRES
OVER SASK INTO NRN MANITOBA AND LOW PRES OVER THE LOWER MS VALLEY.
IR SATELLITE LOOP SHOWED AN EXTENSIVE AREA OF CLOUDS ACROSS THE
REGION WITH A RELATIVELY SMALL CLEAR AREA NE OF LAKE SUPERIOR.
WITH GENERALLY WEAK ONSHORE WINDS INTO NRN UPPER MI
OVERNIGHT...RADAR INDICATED NO PCPN. HOWEVER...AS WINDS INCREASE OUT
OF THE NORTHEAST AND 850 MB TEMPS REMAIN NER -11C...EXPECT SOME
LIGHT SNOW MAY STILL DEVELOP OVER THE WEST AND N CNTRL LOCATIONS
WHERE UPSLOPE FLOW PREVAILS. SINCE TEMPS IN THE MOIST LAYER REMAINED
BORDERLINE TO SUPPORT ICE CRYSTALS...A MIX OF -SN/FLURRIES/-FZDZ MAY
BE POSSIBLE. MODELS SUGGEST THAT THE DRY AIR TO THE NORTHEAST WILL
SPREAD ACROSS LAKE SUPERIOR INTO UPPER MI THIS AFTERNOON. THIS
SHOULD BRING AN END TO ANY PCPN THAT DEVELOPS EARLY TODAY. SOME
CLEARING MAY ALSO SPREAD FROM EAST INTO CNTRL UPPER MI BY LATE THIS
AFTERNOON WHICH SHOULD HELP BOOST TEMPS INTO THE LOWER TO MID 30S.
THE MODELS WERE CONSISTENT IN BRINGING ANOTHER BATCH OF 925-700 MB
MOISTURE INTO THE AREA FROM THE NORTHEAST TONIGHT. THIS WILL BRING
INCREASING CHANCES FOR LIGHT LAKE EFFECT SNOW...ESPECIALLY AFT
06Z...TO AREAS FAVORED BY UPSLOPE NNE FLOW IN N CNTRL AND WRN UPPER
MI. SINCE DEEPER MOISTURE TO AROUND -12C IS LIKELY...-FZDZ CHANCES
WILL BE REDUCED. THE CLOUDS WILL ALSO KEEP TEMPS FROM FALLING OFF
TOO MUCH WITH MIN READINGS AGAIN ABOVE NORMAL....IN THE LOW TO MID
20S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 443 AM EDT SUN MAR 24 2013
OUR STEADY NORTHERLY FLOW OFF LAKE SUPERIOR WILL CONTINUE THROUGH
WEDNESDAY...WITH LIGHT PRECIPITATION POSSIBLE NEARLY EVERY DAY NEAR
LAKE SUPERIOR. LOOK FOR TEMPERATURES TO SLOWLY INCREASE EACH
DAY...WITH SOUTH CENTRAL AREAS NEARING 40 DEGREES FOR A HIGH ON
THURSDAY...AND REMAINING IN THE UPPER 30S AND LOW 40S TO WRAP UP THE
WORK WEEK AND START THE UPCOMING WEEKEND.
THE NEXT GOOD SURGE OF PRECIPITATION WILL BE MONDAY THROUGH TUESDAY
MORNING...AS THE MID ATLANTIC LOW ROTATES MOISTURE BACK TOWARD THE
UPPER GREAT LAKES REGION. STILL IT WILL BE SET UP AOB ABOUT
800MB...WITH THE DGZ HOVERING AT THE TOP OF THIS MOISTURE LAYER TO
AROUND 600MB. WHILE THE MOST PRISTINE SNOW CRYSTALS WILL NOT BE
EXPECTED...850MB TEMPS HOVERING BETWEEN -10 AND -12C. SNOW AMOUNTS
AROUND A HALF INCH EVERY 6 HOURS WILL BE POSSIBLE MONDAY THROUGH
TUESDAY MORNING...HIGHEST OVER THE ELEVATED TERRAIN OF MARQUETTE
COUNTY...AND ACROSS WESTERN GOGEBIC AND ONTONAGON COUNTIES.
THE 500MB TROUGH WILL LIKELY REMAIN ENTRENCHED ACROSS CENTRAL AND
EASTERN UPPER MICHIGAN THROUGH TUESDAY NIGHT INTO WEDNESDAY. AT THAT
POINT NW FLOW LOOKS TO TAKE OVER ALOFT...WITH A SERIES OF WEAKER
WAVES SLIDING NEAR THE UPPER GREAT LAKES. WHILE WE DO HAVE SLIGHT
CHANCE POPS MENTIONED FOR DAY 5/FRIDAY INTO DAY 6/SATURDAY...THE
CONFIDENCE IS VERY LOW. THE ECMWF KEEP LOW PRESSURE STUCK UP NEAR
JAMES BAY AND HUDSON BAY ON FRIDAY...WITH HIGH PRESSURE STRETCHING
FROM SOUTH CENTRAL CANADA THROUGH THE UPPER GREAT LAKES. A WEAK COLD
FRONT MAY CROSS THURSDAY NIGHT INTO FRIDAY. THE 00Z MODEL RUNS LOOK
LESS THAN IMPRESSIVE WITH THE CHANCE FOR MEASURABLE PRECIP THROUGH
THE END OF THE FORECAST PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 133 AM EDT SUN MAR 24 2013
MVFR CONDITIONS SHOULD GENERALLY PREVAIL THROUGHOUT THE NIGHT AND
INTO SUNDAY MORNING WITH NORTH TO NORTHEAST FLOW ACROSS THE REGION.
LATEST SATELLITE IMAGERY SUGGESTS SOME BREAKS IN THE CLOUDS NEAR CMX
AND IWD WHICH MAY KEEP BRIEF PERIODS OF VFR FOR THE NEXT HOUR OR
SO...BUT IN GENERAL CONDITIONS SHOULD REMAIN MVFR. THE UPSLOPE FLOW
COMBINED WITH THE LOW LEVEL MOISTURE THAT HAS BEEN IN PLACE FOR THE
LAST SEVERAL DAYS SHOULD ALLOW FOR SOME FREEZING DRIZZLE TO DEVELOP
OVERNIGHT...ESPECIALLY AT SAW WHERE N-NE FLOW IS HIGHLY FAVORABLE
FOR UPSLOPE FREEZING DRIZZLE. SOME SLIGHT IMPROVEMENT LATER IN THE
DAY ON SUNDAY AS DRIER AIR BUILDS INTO THE AREA AS STRONGER AND
DEEPER NE FLOW SPREADS ACROSS THE AREA. SITES MAY IMPROVE TO VFR BY
LATE SUN AFTN OR SUN EVENING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 502 AM EDT SUN MAR 24 2013
HIGH PRESSURE OVER CENTRAL CANADA WILL KEEP A RIDGE OVER THE UPPER
GREAT LAKES REGION TODAY. BUT AS A LOW PRESSURE SYSTEM
DEPARTS THE CENTRAL PLAINS AND MOVES THROUGH THE OHIO RIVER VALLEY
THROUGH MONDAY NIGHT...THE RIDGE WILL WEAKEN AND SHIFT WEST. THIS
WILL LEAD TO PERSISTENT NORTHERLY FLOW ACROSS THE AREA...ALTHOUGH
THE WINDS SHOULD BE AT OR BELOW 25 KNOTS. AS THE LOW SHIFTS OFF
THE ATLANTIC SEABOARD ON TUESDAY...HIGH PRESSURE WILL BEGIN TO SHIFT
BACK TO THE EAST AND COVER THE UPPER GREAT LAKES FROM TUESDAY NIGHT
THROUGH THE REST OF THE WORK WEEK. THIS WILL KEEP THE NORTHERLY
WINDS BELOW 15KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...MRD
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
443 AM EDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 858 PM EDT SAT MAR 23 2013
NO MAJOR CHANGES TO THE GOING FORECAST. OVERNIGHT SHIFT WILL NEED TO
WATCH FOR HEAVIER FREEZING DRIZZLE IN THE UPSLOPE AREAS OF NORTH
CENTRAL UPPER MICHIGAN. THE 18Z NAM AND 21Z RAP BOTH SUGGEST A
PERIOD OF MODERATE UPWARD MOTION AS THE UPSLOPE FLOW INCREASES WHEN
THE PBL WINDS BECOME N-NE. BOTH OF THESE MODELS SHOW A SATURATED
LAYER BETWEEN -6 AND -12C WHICH WOULD INDICATE THAT MOSTLY
SUPERCOOLED WATER WITH VERY LITTLE ICE NUCLEATION. IN FACT...THIS IS
WHAT HAS BEEN SEEN AT THE OFFICE THIS EVENING AND HAS ALLOWED FOR A
GLAZE ON ELEVATED SURFACES. HAVE OPTED TO ISSUE TO SPECIAL WEATHER
STATEMENT TO ACCOUNT FOR POTENTIAL SLIPPERY ROADS OVERNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 353 PM EDT SAT MAR 23 2013
DON/T EXPECT THE WEATHER TO BE MUCH DIFFERENT THAN THE LAST DAY OR
TWO. THIS OVERALL QUIET PATTERN IS DUE TO THE STRONG NEGATIVE NAO
BLOCKING PATTERN PUSHING THE JET STREAM FARTHER SOUTH AND KEEPING
THE STORM TRACK WELL TO THE SOUTH OF THE AREA. THE MAIN SYSTEM TO
BE AFFECTING LOCATIONS WELL TO THE SOUTH OF OUR CWA WILL MOVE FROM
CENTRAL PLAINS THIS AFTERNOON TO THE OHIO RIVER VALLEY ON SUNDAY.
WHILE THIS SYSTEM TRACKS TO THE SOUTH...NORTHEASTERLY FLOW ALOFT
WILL KEEP THE COLDER 850MB TEMPS...AROUND -11C OR 4-6
DEGREES BELOW NORMAL...OVER THE AREA DURING THE SHORT TERM PERIOD.
THE MOISTURE OVER THE AREA IS FAIRLY SHALLOW...AROUND
975-900MB...FOR TONIGHT AND SUNDAY MORNING BEFORE A POCKET OF DRIER
AIR ARRIVES ON SUNDAY AFTERNOON FROM THE NORTHEAST. SKIES MAY
SCATTER OUT A LITTLE BIT BASED OFF SOME OF THE GAPS OVER
LAKE SUPERIOR AND WITH THE LOSS OF DIURNAL HEATING...BUT WITH
CLOUDS MAKING THEIR WAY SOUTH OVER THE NORTHERN LAKE AND MODELS
SHOWING DECENT MOISTURE PRESENT...WOULD EXPECT CLOUDS TO QUICKLY
FILL BACK IN TONIGHT. THUS...EXPECT MOSTLY CLOUDY CONDITIONS TO
AFFECT THE AREA TONIGHT INTO SUNDAY MORNING...BUT AS THE DRIER AIR
WORKS IN FROM THE NORTHEAST ON SUNDAY...A DECREASING CLOUD TREND IS
EXPECTED THROUGH THE LATER AFTERNOON HOURS OVER THE NORTHEAST
HALF OF THE CWA.
AS FOR PRECIPITATION...WOULD EXPECT IT TO BE SIMILAR TO THE LAST TWO
DAYS WHERE IT PEAKS UP DURING THE OVERNIGHT HOURS DUE TO REDUCED
MIXING. THIS IS ESPECIALLY TRUE IN THE NORTHEAST WIND FAVORED
LOCATIONS DUE TO WINDS VEERING FROM A MORE VARIABLE NORTHERLY
DIRECTION LATE THIS AFTERNOON TO A PERSISTENT NORTHEAST DIRECTION
TONIGHT WITH THE WEAKENING HIGH PRESSURE RIDGE AND LOW EXITING THE
CENTRAL PLAINS. BUMPED UP POPS TO CHANCES OVER THE HIGHER TERRAIN OF
THE NORTH CENTRAL LATE TONIGHT BASED ON ALL OF THE HIGHER RESOLUTION
MODELS PICKING UP ON THE UPSLOPE FORCING AND INCREASED 950-925MB
OMEGA. WITH THE DRIER AIR LIKELY ARRIVING ON LATE
SUNDAY MORNING...WOULD EXPECT IT TO COME TO AN END FAIRLY QUICKLY ON
SUNDAY AFTERNOON. SINCE CLOUD IS STILL LOCATED IN THE BORDERLINE
ICE CRYSTAL REGION...WILL CONTINUE TO MENTION FREEZING DRIZZLE
ALONG WITH THE SNOW TONIGHT INTO SUNDAY MORNING. FINALLY...DID ADD A
FEW FLURRIES OVER THE INTERIOR WEST DUE TO DIURNAL HEATING
INCREASING THE LOW LEVEL LAPSE RATES AND POTENTIALLY LEADING TO SOME
LIGHT FLURRIES TOWARDS THE AFTERNOON WITH THE LINGER MOISTURE.
LOWS TONIGHT WILL DEPEND ON CLOUD COVER AND THINK THE COOLEST
LOCATIONS WILL BE OVER THE EASTERN CWA. LAST NIGHT...WHERE IT
CLEARED OUT OVER THE EAST...LOCATIONS FELL INTO THE SINGLE DIGITS
ABOVE ZERO. HAVE FOLLOWED THAT IDEA FOR SPINCICH LAKE...BUT BANKED
ON MORE CLOUDS OVER THE REST OF THE AREA AND WENT WITH UPPER TEENS
OR LOWER 20S. HIGHS ON SUNDAY SHOULDN/T BE MUCH DIFFERENT THAN
TODAY AND WILL CONTINUE TO MENTION LOW TO MID 30S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 443 AM EDT SUN MAR 24 2013
OUR STEADY NORTHERLY FLOW OFF LAKE SUPERIOR WILL CONTINUE THROUGH
WEDNESDAY...WITH LIGHT PRECIPITATION POSSIBLE NEARLY EVERY DAY NEAR
LAKE SUPERIOR. LOOK FOR TEMPERATURES TO SLOWLY INCREASE EACH
DAY...WITH SOUTH CENTRAL AREAS NEARING 40 DEGREES FOR A HIGH ON
THURSDAY...AND REMAINING IN THE UPPER 30S AND LOW 40S TO WRAP UP THE
WORK WEEK AND START THE UPCOMING WEEKEND.
THE NEXT GOOD SURGE OF PRECIPITATION WILL BE MONDAY THROUGH TUESDAY
MORNING...AS THE MID ATLANTIC LOW ROTATES MOISTURE BACK TOWARD THE
UPPER GREAT LAKES REGION. STILL IT WILL BE SET UP AOB ABOUT
800MB...WITH THE DGZ HOVERING AT THE TOP OF THIS MOISTURE LAYER TO
AROUND 600MB. WHILE THE MOST PRISTINE SNOW CRYSTALS WILL NOT BE
EXPECTED...850MB TEMPS HOVERING BETWEEN -10 AND -12C. SNOW AMOUNTS
AROUND A HALF INCH EVERY 6 HOURS WILL BE POSSIBLE MONDAY THROUGH
TUESDAY MORNING...HIGHEST OVER THE ELEVATED TERRAIN OF MARQUETTE
COUNTY...AND ACROSS WESTERN GOGEBIC AND ONTONAGON COUNTIES.
THE 500MB TROUGH WILL LIKELY REMAIN ENTRENCHED ACROSS CENTRAL AND
EASTERN UPPER MICHIGAN THROUGH TUESDAY NIGHT INTO WEDNESDAY. AT THAT
POINT NW FLOW LOOKS TO TAKE OVER ALOFT...WITH A SERIES OF WEAKER
WAVES SLIDING NEAR THE UPPER GREAT LAKES. WHILE WE DO HAVE SLIGHT
CHANCE POPS MENTIONED FOR DAY 5/FRIDAY INTO DAY 6/SATURDAY...THE
CONFIDENCE IS VERY LOW. THE ECMWF KEEP LOW PRESSURE STUCK UP NEAR
JAMES BAY AND HUDSON BAY ON FRIDAY...WITH HIGH PRESSURE STRETCHING
FROM SOUTH CENTRAL CANADA THROUGH THE UPPER GREAT LAKES. A WEAK COLD
FRONT MAY CROSS THURSDAY NIGHT INTO FRIDAY. THE 00Z MODEL RUNS LOOK
LESS THAN IMPRESSIVE WITH THE CHANCE FOR MEASURABLE PRECIP THROUGH
THE END OF THE FORECAST PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 133 AM EDT SUN MAR 24 2013
MVFR CONDITIONS SHOULD GENERALLY PREVAIL THROUGHOUT THE NIGHT AND
INTO SUNDAY MORNING WITH NORTH TO NORTHEAST FLOW ACROSS THE REGION.
LATEST SATELLITE IMAGERY SUGGESTS SOME BREAKS IN THE CLOUDS NEAR CMX
AND IWD WHICH MAY KEEP BRIEF PERIODS OF VFR FOR THE NEXT HOUR OR
SO...BUT IN GENERAL CONDITIONS SHOULD REMAIN MVFR. THE UPSLOPE FLOW
COMBINED WITH THE LOW LEVEL MOISTURE THAT HAS BEEN IN PLACE FOR THE
LAST SEVERAL DAYS SHOULD ALLOW FOR SOME FREEZING DRIZZLE TO DEVELOP
OVERNIGHT...ESPECIALLY AT SAW WHERE N-NE FLOW IS HIGHLY FAVORABLE
FOR UPSLOPE FREEZING DRIZZLE. SOME SLIGHT IMPROVEMENT LATER IN THE
DAY ON SUNDAY AS DRIER AIR BUILDS INTO THE AREA AS STRONGER AND
DEEPER NE FLOW SPREADS ACROSS THE AREA. SITES MAY IMPROVE TO VFR BY
LATE SUN AFTN OR SUN EVENING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 353 PM EDT SAT MAR 23 2013
A HIGH PRESSURE OVER CENTRAL CANADA WILL KEEP A RIDGE OVER THE
UPPER GREAT LAKES REGION INTO SUNDAY MONRING. BUT AS A LOW PRESSURE
SYSTEM DEPARTS THE CENTRAL PLAINS AND MOVES THROUGH THE OHIO RIVER
VALLEY THROUGH MONDAY NIGHT...THE RIDGE WILL WEAKEN AND SHIFT WEST.
THIS WILL LEAD TO PERSISTENT NORTHERLY FLOW ACROSS THE
AREA...ALTHOUGH THE WINDS SHOULD BE LESS THAN 25 KNOTS. AS THE
LOW SHIFTS OFF THE ATLANTIC SEABOARD ON TUESDAY...HIGH PRESSURE
WILL BEGIN TO SHIFT BACK TO THE EAST AND COVER THE UPPER GREAT
LAKES FROM TUESDAY NIGHT THROUGH THE REST OF THE WORK WEEK. THIS
WILL KEEP THE NORTHERLY WINDS BELOW 15KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...MRD
SHORT TERM...SRF
LONG TERM...KF
AVIATION...MRD
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
134 AM EDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 858 PM EDT SAT MAR 23 2013
NO MAJOR CHANGES TO THE GOING FORECAST. OVERNIGHT SHIFT WILL NEED TO
WATCH FOR HEAVIER FREEZING DRIZZLE IN THE UPSLOPE AREAS OF NORTH
CENTRAL UPPER MICHIGAN. THE 18Z NAM AND 21Z RAP BOTH SUGGEST A
PERIOD OF MODERATE UPWARD MOTION AS THE UPSLOPE FLOW INCREASES WHEN
THE PBL WINDS BECOME N-NE. BOTH OF THESE MODELS SHOW A SATURATED
LAYER BETWEEN -6 AND -12C WHICH WOULD INDICATE THAT MOSTLY
SUPERCOOLED WATER WITH VERY LITTLE ICE NUCLEATION. IN FACT...THIS IS
WHAT HAS BEEN SEEN AT THE OFFICE THIS EVENING AND HAS ALLOWED FOR A
GLAZE ON ELEVATED SURFACES. HAVE OPTED TO ISSUE TO SPECIAL WEATHER
STATEMENT TO ACCOUNT FOR POTENTIAL SLIPPERY ROADS OVERNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 353 PM EDT SAT MAR 23 2013
DON/T EXPECT THE WEATHER TO BE MUCH DIFFERENT THAN THE LAST DAY OR
TWO. THIS OVERALL QUIET PATTERN IS DUE TO THE STRONG NEGATIVE NAO
BLOCKING PATTERN PUSHING THE JET STREAM FARTHER SOUTH AND KEEPING
THE STORM TRACK WELL TO THE SOUTH OF THE AREA. THE MAIN SYSTEM TO
BE AFFECTING LOCATIONS WELL TO THE SOUTH OF OUR CWA WILL MOVE FROM
CENTRAL PLAINS THIS AFTERNOON TO THE OHIO RIVER VALLEY ON SUNDAY.
WHILE THIS SYSTEM TRACKS TO THE SOUTH...NORTHEASTERLY FLOW ALOFT
WILL KEEP THE COLDER 850MB TEMPS...AROUND -11C OR 4-6
DEGREES BELOW NORMAL...OVER THE AREA DURING THE SHORT TERM PERIOD.
THE MOISTURE OVER THE AREA IS FAIRLY SHALLOW...AROUND
975-900MB...FOR TONIGHT AND SUNDAY MORNING BEFORE A POCKET OF DRIER
AIR ARRIVES ON SUNDAY AFTERNOON FROM THE NORTHEAST. SKIES MAY
SCATTER OUT A LITTLE BIT BASED OFF SOME OF THE GAPS OVER
LAKE SUPERIOR AND WITH THE LOSS OF DIURNAL HEATING...BUT WITH
CLOUDS MAKING THEIR WAY SOUTH OVER THE NORTHERN LAKE AND MODELS
SHOWING DECENT MOISTURE PRESENT...WOULD EXPECT CLOUDS TO QUICKLY
FILL BACK IN TONIGHT. THUS...EXPECT MOSTLY CLOUDY CONDITIONS TO
AFFECT THE AREA TONIGHT INTO SUNDAY MORNING...BUT AS THE DRIER AIR
WORKS IN FROM THE NORTHEAST ON SUNDAY...A DECREASING CLOUD TREND IS
EXPECTED THROUGH THE LATER AFTERNOON HOURS OVER THE NORTHEAST
HALF OF THE CWA.
AS FOR PRECIPITATION...WOULD EXPECT IT TO BE SIMILAR TO THE LAST TWO
DAYS WHERE IT PEAKS UP DURING THE OVERNIGHT HOURS DUE TO REDUCED
MIXING. THIS IS ESPECIALLY TRUE IN THE NORTHEAST WIND FAVORED
LOCATIONS DUE TO WINDS VEERING FROM A MORE VARIABLE NORTHERLY
DIRECTION LATE THIS AFTERNOON TO A PERSISTENT NORTHEAST DIRECTION
TONIGHT WITH THE WEAKENING HIGH PRESSURE RIDGE AND LOW EXITING THE
CENTRAL PLAINS. BUMPED UP POPS TO CHANCES OVER THE HIGHER TERRAIN OF
THE NORTH CENTRAL LATE TONIGHT BASED ON ALL OF THE HIGHER RESOLUTION
MODELS PICKING UP ON THE UPSLOPE FORCING AND INCREASED 950-925MB
OMEGA. WITH THE DRIER AIR LIKELY ARRIVING ON LATE
SUNDAY MORNING...WOULD EXPECT IT TO COME TO AN END FAIRLY QUICKLY ON
SUNDAY AFTERNOON. SINCE CLOUD IS STILL LOCATED IN THE BORDERLINE
ICE CRYSTAL REGION...WILL CONTINUE TO MENTION FREEZING DRIZZLE
ALONG WITH THE SNOW TONIGHT INTO SUNDAY MORNING. FINALLY...DID ADD A
FEW FLURRIES OVER THE INTERIOR WEST DUE TO DIURNAL HEATING
INCREASING THE LOW LEVEL LAPSE RATES AND POTENTIALLY LEADING TO SOME
LIGHT FLURRIES TOWARDS THE AFTERNOON WITH THE LINGER MOISTURE.
LOWS TONIGHT WILL DEPEND ON CLOUD COVER AND THINK THE COOLEST
LOCATIONS WILL BE OVER THE EASTERN CWA. LAST NIGHT...WHERE IT
CLEARED OUT OVER THE EAST...LOCATIONS FELL INTO THE SINGLE DIGITS
ABOVE ZERO. HAVE FOLLOWED THAT IDEA FOR SPINCICH LAKE...BUT BANKED
ON MORE CLOUDS OVER THE REST OF THE AREA AND WENT WITH UPPER TEENS
OR LOWER 20S. HIGHS ON SUNDAY SHOULDN/T BE MUCH DIFFERENT THAN
TODAY AND WILL CONTINUE TO MENTION LOW TO MID 30S.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 353 PM EDT SAT MAR 23 2013
SUN NIGHT AND MON...AS A MID-LEVEL AND SFC LOW MOVES THROUGH THE
OHIO VALLEY REACHING THE MID-ATLANTIC COAST MONDAY
AFTERNOON...MODELS SUGGEST INCREASING 850-700 MB MOISTURE WILL BE
DRAWN TOWARD UPPER MICHIGAN FROM THE NORTHEAST. THE INCREASED
MOISTURE COMBINED WITH NNE FLOW AND 850 MB TEMPS REMAINING IN THE
-10C TO -11C RANGE WILL BE ENOUGH TO SUPPORT AT LEAST SCT SNOW
SHOWERS INTO THE WEST AND N CNTRL PORTIONS OF THE CWA. ANY LOCAL
SNOWFALL ACCUMULATIONS FM THESE SHOWERS SHOULD REMAIN LIGHT...AROUND
A HALF INCH OR LESS PER 12 HRS.
TUE...MOISTURE TO NEAR 800 MB IN THE MORNING AND 850 MB TEMPS
LINGERING IN THE -10 TO -12C RANGE...SHOULD STILL RESULT IN
SCT/ISOLD -SHSN WEST AND N CNTRL COUNTIES IN THE MORNING WITH NRLY
FLOW. EXPECT THE PCPN TO DIMINISH DURING THE AFTERNOON ESPECIALLY
NCNTRL WHERE SIGNIFICANT 850-700 MB DRYING IS EXPECTED...PER
GFS/ECMWF MOISTURE FCST.
WED AND THU...WITH WEAK MID LEVEL AND SFC RIDGING EXPECTED AND
DRYING/SUBSIDENCE NOTED ON MODEL SNDGS...LOOK FOR DRY CONDITIONS
WITH GREATER SUNSHINE AS HIGH TEMPS SLOWLY MODERATE INTO THE MID TO
UPPER 30S BY THU.
FRI AND SAT...THE 12Z GFS...ECMWF AND GEM-NH HAVE ALL TRENDED
FARTHER SOUTH WITH COMPACT MID LEVEL LOW APPROACHING FM SOUTH
CENTRAL CANADA AND MOVING ACROSS THE NRN PORTION OF LAKE SUPERIOR
FRI AFTERNOON INTO SATURDAY. GIVEN THE WEAK TO MODERATE Q-VECT CONV
SPREADING INTO THE AREA ALONG THE ASSOCIATED COLD FRONT HAVE DECIDED
TO INTRODUCE SLIGHT CHC POPS FOR FRIDAY INTO SATURDAY. WEAK CAA
BEHIND THE FRONT COULD ALSO CONTRIBUTE TO LIGHT SCT LAKE EFFECT SNOW
SHOWERS FRIDAY NIGHT INTO SATURDAY ACROSS THE NRN TIER AND ERN
COUNTIES IN NW FLOW. ONLY SLIGHT CHC POPS WARRANTED AT THIS TIME AS
THIS IS THE FIRST MODEL RUN TO SHOW THE FARTHER SOUTH TRACK WITH
CANADIAN MID-LVL LOW. IF MODELS CONTINUE TO TREND FARTHER SOUTH WITH
THIS SYSTEM...THEN POPS EVENTUALLY WILL NEED TO INCREASED FOR LATE
NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 133 AM EDT SUN MAR 24 2013
MVFR CONDITIONS SHOULD GENERALLY PREVAIL THROUGHOUT THE NIGHT AND
INTO SUNDAY MORNING WITH NORTH TO NORTHEAST FLOW ACROSS THE REGION.
LATEST SATELLITE IMAGERY SUGGESTS SOME BREAKS IN THE CLOUDS NEAR CMX
AND IWD WHICH MAY KEEP BRIEF PERIODS OF VFR FOR THE NEXT HOUR OR
SO...BUT IN GENERAL CONDITIONS SHOULD REMAIN MVFR. THE UPSLOPE FLOW
COMBINED WITH THE LOW LEVEL MOISTURE THAT HAS BEEN IN PLACE FOR THE
LAST SEVERAL DAYS SHOULD ALLOW FOR SOME FREEZING DRIZZLE TO DEVELOP
OVERNIGHT...ESPECIALLY AT SAW WHERE N-NE FLOW IS HIGHLY FAVORABLE
FOR UPSLOPE FREEZING DRIZZLE. SOME SLIGHT IMPROVEMENT LATER IN THE
DAY ON SUNDAY AS DRIER AIR BUILDS INTO THE AREA AS STRONGER AND
DEEPER NE FLOW SPREADS ACROSS THE AREA. SITES MAY IMPROVE TO VFR BY
LATE SUN AFTN OR SUN EVENING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 353 PM EDT SAT MAR 23 2013
A HIGH PRESSURE OVER CENTRAL CANADA WILL KEEP A RIDGE OVER THE
UPPER GREAT LAKES REGION INTO SUNDAY MONRING. BUT AS A LOW PRESSURE
SYSTEM DEPARTS THE CENTRAL PLAINS AND MOVES THROUGH THE OHIO RIVER
VALLEY THROUGH MONDAY NIGHT...THE RIDGE WILL WEAKEN AND SHIFT WEST.
THIS WILL LEAD TO PERSISTENT NORTHERLY FLOW ACROSS THE
AREA...ALTHOUGH THE WINDS SHOULD BE LESS THAN 25 KNOTS. AS THE
LOW SHIFTS OFF THE ATLANTIC SEABOARD ON TUESDAY...HIGH PRESSURE
WILL BEGIN TO SHIFT BACK TO THE EAST AND COVER THE UPPER GREAT
LAKES FROM TUESDAY NIGHT THROUGH THE REST OF THE WORK WEEK. THIS
WILL KEEP THE NORTHERLY WINDS BELOW 15KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...MRD
SHORT TERM...SRF
LONG TERM...VOSS
AVIATION...MRD
MARINE...SRF
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
436 AM CDT SUN MAR 24 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 336 AM CDT SUN MAR 24 2013
PRIMARY FCST ISSUE FOR TODAY IS THE ONGOING WINTER STORM. WAA PCPN
WHICH DVLPD ACROSS THE AREA LAST NIGHT BRIEFLY CHANGED OVER TO A
RAIN/SNOW MIX AND EVEN SWITCHED OVER TO PURE SNOW IN SOME
LOCATIONS BEFORE ENDING. THERE WILL BE A BRIEF BREAK EARLY THIS
MORNING BETWEEN THE DEPARTING WAA PCPN AND THE HEAVIER SNOW
ASSOCIATED WITH THE DEFORMATION ZONE WHICH HAS ALREADY DVLPD IN
ERN KS AND WRN MO. MODELS ARE IN GENERALLY GOOD AGREEMENT THIS
MORNING WITH THE TRACK OF THE LOW PRESSURE SYSTEM...ESPECIALLY THE
ECMWF WHICH HAS BEEN FAIRLY CONSISTENT WITH THE TRACK OF THE H85
LOW ALTHOUGH THE 24/00Z RUN IS SOMEWHAT SLOWER THAN THE 23/00Z RUN
BETWEEN 12Z AND 18Z. THE TRACK OF THE H85 CIRCULATION CENTER FROM
NEAR KSGF/KUMN TO NEAR KFAM/KMDH IS VERY FAVORABLE FOR HEAVY SNOW
ACROSS THE CENTRAL PART OF THE CWA BASED ON LOCAL CLIMATOLOGY
PLOTS.
THERE ARE TWO ASPECTS OF THIS EVENT THAT REALLY CAUGHT MY
ATTENTION. FIRST...BUFKIT CROSS SECTIONS FROM A COUPLE OF MODELS
/INCLUDING THE RAP AND SREF/ SHOW VERY STRONG LIFT FOCUSED THROUGH
A RESPECTABLY DEEP DENDRITIC GROWTH ZONE WHICH IS OCCASIONALLY
SUPERSATURATED WITH RESPECT TO ICE. THIS IS ESPECIALLY TRUE
BETWEEN 15Z AND 00Z. SECOND...NO MATTER HOW YOU SLICE THE
ATMOSPHERE...THERE ARE INDICATIONS OF MODEST INSTABILITY /AT LEAST
FOR A WINTER EVENT/ ACROSS PARTS OF MO/IL TODAY. FCSTS OF H7-H5
LAPSE RATES EXCEED 7 DEG C/KM ACROSS THE SRN HALF OF THE CWA ON
THE RAP/WRF/SREF/NAM/GFS/UKMET AND EVEN THE ECMWF FCST EXCEEDS 6.5
DEG C/KM. BUFKIT SOUNDINGS ALSO SHOW UP TO 50 J/KG OF ELEVATED
CAPE AT TIMES. TAKEN TOGETHER...THESE TWO ITEMS SUGGEST THAT THERE
WILL BE PERIODS OF EFFICIENT SNOWFALL PRODUCTION WITHIN THE
DEFORMATION ZONE ALONG WITH OCCASIONAL CONVECTIVE ELEMENTS WHICH
WILL LOCALLY ENHANCE SNOWFALL RATES. IN TERMS OF SNOWFALL
AMOUNTS...IT STILL LOOKS LIKE A SOLID 6-8 INCHES OF SNOW ACROSS
THE WINTER STORM WARNING AREA WITH HIGHER AMOUNTS POSSIBLE.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 24 2013
(TONIGHT - MONDAY NIGHT)
MODELS HAVE ALL COME INTO A HARMONIOUS CONFLUENCE OF SOLUTIONS WITH
THE 00Z RUNS...WITH THE AGREED UPON TRACK MOST SIMILAR TO THE ECMWF
24HRS AGO...WITH THE GFS/NAM MORE SLY...AND THE GEM MORE NLY...AND
PLACES THIS STORM IN ABOUT THE MOST PERFECT SPOT TO MAXIMIZE SNOW
TOTALS ACROSS THE I-70 CORRIDOR WITH AN ELONGATED H850 LO TRACKING
THRU SRN MO AND SRN IL. ANOTHER TREND...THIS ONE TEMPORAL...HAS
BEEN TO SLOW DOWN THE EWD TRANSLATION OF THE STORM BY ABOUT 6HRS...
MEANING THE DEF ZONE PCPN FROM IT WILL LINGER WELL INTO THIS EVENING
FOR THE IL COUNTIES AND AREAS JUST W OF THE MS RIVER AND PERHAPS
EARLY OVERNIGHT FOR PARTS OF SWRN-SRN IL. SNOWFALL TOTALS HAVE BEEN
BUMPED UP AS A RESULT OF THE SLOWER EXIT...WITH AN ADDITIONAL 2-3"
FOR MUCH OF THE IL COUNTIES AND AROUND AN INCH MORE FOR THE REST.
HAVE EXPANDED THE REACH OF THE WARNING BACK TO THE W A BIT MORE. BY
THE TIME IT IS ALL SAID AND DONE...THE PALM SUNDAY SNOWSTORM OF 2013
IS EXPECTED TO BE ONE OF THOSE ONCE-IN-A-GENERATION TYPE STORMS FOR
OCCURRING SO LATE IN THE YEAR AND BEING SO POTENT.
THIS POTENT STORM SYSTEM WILL BE EXITING JUST AS ANOTHER...WEAKER...
SYSTEM MOVES IN. THIS SYSTEM IS THE OLD MONTANA LO THAT IS EXPECTED
TO OPEN UP LATER TODAY AND GET SUCKED IN THE UNDERTOW OF TODAY AND
THIS EVENING/S STORM SYSTEM...BECOMING SHEARED BY THE TIME IT
REACHES OUR AREA LATER TONIGHT AND CONTINUING INTO MONDAY...BUT WITH
ENOUGH TO KEEP EITHER THE LIGHT SNOW OR SNOW SHOWERS GOING THRU LATE
MONDAY. SNOW ACCUMS LOOK TO BE AROUND AN ADDITIONAL INCH FOR MOST
AREAS...BUT OVER THE COURSE OF ANOTHER 12HRS OR SO. DEPENDING ON
HOW THIS ALL WORKS OUT...THE NATURE OF SHSN MAY SEE LOCALIZED HIGHER
AMOUNTS POSSIBLE. THE PERSISTENT LO CLOUDS SHOULD HANG IN TOUGH
THRU MONDAY AND WITH NW LO LEVEL WINDS AND LOTS OF FRESH SNOW
PACK...WHAT INSOLATION DOES MAKE IT THRU WILL GET MOSTLY BOUNCED
BACK...AND SO LOOK FOR MINIMAL TEMP RISES THIS DAY AS WELL...AND MOS
SEEMS TO HIGH ONCE AGAIN. UNDERCUT THE COLDER MET MOS NUMBERS BY A
COUPLE DEGS.
PERSISTENT CYCLONIC FLOW AND CLOUDS CONTINUE INTO MONDAY NIGHT AND
HAVE KEPT MENTION OF FLURRIES.
(TUESDAY - SATURDAY)
NW UPPER LEVEL FLOW WILL THEN CONTINUE FOR THE REMAINDER OF THE WEEK
CONTINUING THE BELOW AVERAGE TEMP REGIME AND ROUNDING OUT OUR RATHER
COLD MARCH. AN INVERTED TROF FOR THURSDAY AND THEN A CDFNT FOR
FRIDAY LOOK TO GIVE US SOME PCPN CHCS BY LATE IN THE WEEK...BUT
UNLIKE THE START OF THE WEEK...THESE PCPN CHCS SHOULD BE IN THE FORM
OF LIQUID.
TES
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1043 PM CDT SAT MAR 23 2013
SCATTERED SHOWERS AND AREAS OF RAIN CONTINUE TO MOVE THROUGH THE
TAF SITES THIS EVENING AHEAD OF AN APPROACHING UPPER LEVEL
DISTURBANCE IN THE PLAINS. THE CLOUD CEILINGS WILL GRADUALLY LOWER
INTO THE MVFR CATEGORY BY 06Z SUN AS THE LOW LEVELS OF THE
ATMOSPHERE SATURATE. AS COLDER AIR FILTERS SEWD INTO THE REGION
LATE TGT THE RAIN WILL CHANGE OVER TO SNOW IN UIN AND COU AROUND
06-07Z SUN AND IN THE ST LOUIS METRO AREA AROUND 08-10Z SUN WITH
CEILINGS AND VSBYS LOWERING INTO THE IFR OR LIFR CATEGORY. THERE
MAY BE A BRIEF LULL IN THE SNOW EARLY SUN MRNG...BUT THEN THE SNOW
SHOULD BECOME HEAVY LATE SUN MRNG AND EARLY SUN AFTN AS THE
DEEPENING UPPER LEVEL AND ASSOCIATED SFC LOW PASS S-SE OF THE TAF
SITES. THE SNOW SHOULD TAPER OFF FROM W TO E LATE SUN AFTN AND
SUN EVNG AS THE STORM SYSTEM BEGINS TO PULL E-SE OF OUR AREA WITH
GRADUALLY IMPROVING VSBYS. E-NELY SFC WINDS WILL GRADUALLY BACK AROUND
TO A NLY DIRECTION SUN MRNG...AND THEN TO A NWLY DIRECTION SUN
AFTN. THE SFC WIND SPEEDS WILL INCREASE LATE TGT AND SUN MRNG
ALONG WITH BECOMING GUSTY AS THE SFC LOW DEVELOPS AND DEEPENS SE
OF THE TAF SITES.
SPECIFICS FOR KSTL...PERIODS OF RAIN WILL CONTINUE WITH A
GRADUALLY LOWERING CLOUD CEILING INTO THE MVFR CATEGORY BY 06Z
SUN. THE RAIN WILL CHANGE OVER TO SNOW BETWEEN 08-10Z SUN WITH
CIGS AND VSBYS LOWERING INTO THE IFR OR EVEN LIFR CATEGORY. THERE
MAY BE A BRIEF LULL IN THE PRECIPITATION AROUND 12Z SUN...BUT THEN
RAMP UP LATE SUN MRNG AND CONTINUING EARLY SUN AFTN WITH HEAVY
SNOW AT TIMES. THE SNOW SHOULD GRADUALLY TAPER OFF LATE SUN AFTN
AND THROUGH SUN NGT WITH SLOWLY IMPROVING CEILINGS AND VSBYS. NELY
SFC WIND WILL INCREASE THROUGH THE LATE NGT HOURS AND ON SUN
ALONG WITH BECOMING GUSTY. THE NELY SFC WIND WILL BACK AROUND TO A
NLY DIRECTION SUN MRNG AND A NWLY DIRECTION SUN AFTN. RELATIVELY
STRONG AND GUSTY NWLY SFC WINDS WILL CONTINUE SUN NGT WITH BLOWING
SNOW POSSIBLY REDUCING VSBYS.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM CDT THIS
EVENING FOR CRAWFORD MO-IRON MO-MADISON MO-REYNOLDS MO-ST.
FRANCOIS MO-STE. GENEVIEVE MO-WASHINGTON MO.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR JEFFERSON MO-
LINCOLN MO-PIKE MO-ST. CHARLES MO-ST. LOUIS CITY MO-ST.
LOUIS MO.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR AUDRAIN MO-
BOONE MO-CALLAWAY MO-COLE MO-FRANKLIN MO-GASCONADE MO-KNOX
MO-LEWIS MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-
OSAGE MO-RALLS MO-SHELBY MO-WARREN MO.
IL...WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM CDT THIS
EVENING FOR RANDOLPH IL.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR ADAMS IL-
BOND IL-BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-
JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
157 AM EDT SUN MAR 24 2013
.SYNOPSIS...
A COLD MOIST NORTHWEST FLOW...WILL KEEP SCATTERED SNOW SHOWERS
AND FLURRIES ACROSS MUCH OF THE AREA...INTO EARLY SUNDAY.
THEREAFTER...HIGH PRESSURE WILL BRIEFLY BUILD IN...TO BRING DRY
WEATHER MOST OF SUNDAY AND SUNDAY NIGHT. ON MONDAY...A COMPLEX
STORM SYSTEM IS EXPECTED TO ORGANIZE...ALONG THE MID-ATLANTIC
COAST. THIS SYSTEM HAS THE POTENTIAL...TO BRING SNOW TO PORTIONS
OF THE REGION...WITH THE GREATEST LIKELIHOOD OF ACCUMULATING
SNOWFALL...OVER NORTHEAST PENNSYLVANIA.
&&
.NEAR TERM /THROUGH TODAY/...
1 AM UPDATE...
FCST IN GREAT SHAPE...NO SIGNIFICANT CHANGES NEEDED AT THE PRESENT
TIME. LIGHT LAKE EFFECT SNOWS CONTINUING THIS HR ACROSS PORTIONS
OF CENTRAL NY. ACTIVITY WILL CONTINUE THROUGH THE EARLY MORNING
HRS BEFORE DISSIPATING BY MID TO LATE MORNING. SUNDAY SHAPING UP
TO BE A DECENT DAY WITH SOME CLEARING SKIES EXPECTED DURING THE
EARLY AFTERNOON BEFORE CLOUDS AGAIN MOVE IN TONIGHT. FOCUS STILL
REMAINS ON STORM SYSTEM THAT WILL BE IMPACTING SOUTHERN PORTIONS
OF THE FCST AREA EARLY MON MORNING. MORE DETAILS WITH THE 4 AM
UPDATE.
1010 PM UPDATE...
TEMPS WERE RAISED ABOUT A DEGREE OVERNIGHT DUE TO LAKE ENHANCED
CLOUDS AND FLURRIES STREAMING ACROSS INTERIOR FA. PULLED BACK ON
THE POPS OVER NORTHERN FA EARLY, CONFINING MOST OF THE ACTIVITY TO
SE OF THE FINGER LAKES. BASED ON RAP AND WRFARW WIND PROFILES,
TREND THE SNOW SHOWERS BACK NORTHWARD AS THE ACTIVITY WANES LATE
OVERNIGHT.
750 PM UPDATE...
OPTED TO INCREASE POPS TONIGHT AS LES HAS BLOSSOMED AFTER SUNSET.
HOWEVER SAW NO REASON TO INCREASE SNOW AMOUNTS DUE TO VERY LIGHT
SNOWFALL AND LACK OF SNOW GROWTH. EXTENDED FLURRY ACTIVITY TO THE
SOUTH INTO THE WYOMING VALLEY OF PA.
TEMPS/WINDS IN EXCELLENT SHAPE.
325 PM UPDATE... MULTI-BAND LES REMAINS ACRS PTNS OF CNY LATE THIS
AFTN...ALTHOUGH INTENSITY/ORGANIZATION HAS BEEN COMPROMISED BY
BOTH DECREASING MOISTURE SUPPLY...AND DIURNAL HEATING/BLYR INSTAB.
ALTHOUGH TERRESTRIAL STABILITY WILL INCREASE AGN THIS
EVE...MOISTURE SUPPLY WILL REMAIN FAIRLY SHALLOW...SO MAINLY JUST
FLRYS AND SCTD -SHSN ARE ANTICIPATED OVERNIGHT INTO EARLY
SUN...WITH LITTLE TO NO ADDTNL ACCUMS.
MUCH OF THE DAY SUN SHOULD BE PCPN-FREE...WITH BREAKS OF SUNSHINE
BY AFTN...AS A SFC RIDGE NOSES DOWN FROM ERN CANADA. HIGH TEMPS
WILL REMAIN CHILLY...DESPITE SOME SUN...WITH THE AMS ONLY
SUPPORTING READINGS IN THE UPR 30S TO LWR 40S.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
345 PM UPDATE... THE MAIN SYSTEM OF INTEREST REMAINS THE WV
TRACKING EWD FROM THE OH/TN VLYS TWDS THE MID-ATL COAST LTR SUN
NGT THROUGH MON. NWP CONSENSUS CONTS TO SUGGEST AN UNPHASED SYSTEM
(SEPARATE NRN AND SRN STREAMS) TIL QUITE LATE IN THE EVENT (MON
NGT INTO TUE)...ONCE THE SYSTEM IS ALREADY OFF THE ERN SEABOARD.
ALSO...THE PERSISTENCE OF AN UPR-LVL VORTEX NEAR THE CANADIAN
MARITIMES (CONFLUENT FLOW UNDERNEATH IT)...SHOULD MEAN A FAIRLY
QUICK EXIT TO THE E...ONCE THE CYCLONE REACHES THE MD/VA COASTAL
WATERS.
BOTTOM LN...A QUICK SHOT OF LIFT AND MOISTURE ADVECTION DURG THE
DAY MON...WILL LIKELY BRING A SHORT-LIVED PD OF SNOW. OWING TO
THE PRESENCE OF THE MARITIME UPR LOW MENTIONED ABV...IT APPEARS
THERE IS ONLY SO FAR N THE PCPN SHIELD WILL BE ABLE TO GO...AND
CURRENT MODEL CONSENSUS PAINTS THIS "LINE IN THE SAND" NEAR THE
PA/NY BORDER. POP/QPF/SNOW GRIDS WERE ONLY TWEAKED SLIGHTLY FROM
PERSISTENCE...WITH LIKELY POPS MAINLY CONFINED TO NE PA/SULLIVAN
CNTY...WHERE 1-4" OF SNOW COULD POTENTIALLY FALL. FARTHER N ACRS
CNY...LTL OR NO SNOWFALL SEEMS LIKE THE MOST LIKELY OUTCOME ATTM.
WE`LL CONTINUE TO HIGHLIGHT THIS SYSTEM FOR OUR SRN ZNS IN THE
HWO.
BY TUE...WITH THE COASTAL CYCLONE WELL TO OUR E...A WEAK N TO NW
FLOW WILL RESUME...WITH MORE FLRYS/-SHSN IN THE VICINITY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LTL CHG FROM PREV FCST WITH THE RGN REMAINING UNDER NW FLOW (AFTER
THE DEPARTURE OF THE EARLY WEEK MID ATLC CST STORM)...AND GNRL
UPR LVL TROFFINESS. HPC DATA WAS UTILIZED AS THE BASELINE FCST...BUT
WE ADJUSTED SOME MID-WEEK CLD/POP GRIDS TO INDICATE LOW CHC POPS FOR
-SHSN IN THIS NW FLOW PTRN ACRS CNTRL NY. A VERY GRADUAL MODIFICATION
OF THE COLD TEMPS BY LATE IN THE WORK WEEK.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
NORTHWEST FLOW WILL CONTINUE THROUGH EARLY AFTERNOON BRINGING LAKE
MOISTURE ACROSS THE AREA WITH STRATO CU PERSISTING. IN GENERAL THE
STRATO CU WILL REMAIN LOW VFR BUT BETWEEN 09Z-13Z FLURRIES AND
MVFR CIGS WILL BE POSSIBLE AT ALL TAF SITES BUT KELM/KAVP. THIS
AFTERNOON AS THE FLOW BECOMES N/NE LOW CLOUDS WILL SCATTER OUT AS
CI OVERSPREADS THE REGION. THIS EVENING MID/HIGH CLOUDS WILL
THICKEN OVER THE AREA AS A STORM SYSTEM APPROACHES FROM THE
SOUTH.
N/NW WINDS AROUND 10 KNOTS BECOMING LIGHT AND VARIABLE THIS EVENING.
.OUTLOOK...
MON/MON NGT...MVFR CNTRL NY IN -SHSN...IFR/MVFR NE PA IN SNOW.
TUE/WED/THU/FRI...PATCHY MVFR IN -SHSN MAINLY CNTRL NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJP/MLJ
NEAR TERM...CMG/MLJ
SHORT TERM...MLJ
LONG TERM...
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
104 AM EDT SUN MAR 24 2013
.SYNOPSIS...
A COLD MOIST NORTHWEST FLOW...WILL KEEP SCATTERED SNOW SHOWERS
AND FLURRIES ACROSS MUCH OF THE AREA...INTO EARLY SUNDAY.
THEREAFTER...HIGH PRESSURE WILL BRIEFLY BUILD IN...TO BRING DRY
WEATHER MOST OF SUNDAY AND SUNDAY NIGHT. ON MONDAY...A COMPLEX
STORM SYSTEM IS EXPECTED TO ORGANIZE...ALONG THE MID-ATLANTIC
COAST. THIS SYSTEM HAS THE POTENTIAL...TO BRING SNOW TO PORTIONS
OF THE REGION...WITH THE GREATEST LIKELIHOOD OF ACCUMULATING
SNOWFALL...OVER NORTHEAST PENNSYLVANIA.
&&
.NEAR TERM /THROUGH TODAY/...
1 AM UPDATE...
FCST IN GREAT SHAPE...NO SIGNIFICANT CHANGES NEEDED AT THE PRESENT
TIME. LIGHT LAKE EFFECT SNOWS CONTINUING THIS HR ACROSS PORTIONS
OF CENTRAL NY. ACTIVITY WILL CONTINUE THROUGH THE EARLY MORNING
HRS BEFORE DISSIPATING BY MID TO LATE MORNING. SUNDAY SHAPING UP
TO BE A DECENT DAY WITH SOME CLEARING SKIES EXPECTED DURING THE
EARLY AFTERNOON BEFORE CLOUDS AGAIN MOVE IN TONIGHT. FOCUS STILL
REMAINS ON STORM SYSTEM THAT WILL BE IMPACTING SOUTHERN PORTIONS
OF THE FCST AREA EARLY MON MORNING. MORE DETAILS WITH THE 4 AM
UPDATE.
1010 PM UPDATE...
TEMPS WERE RAISED ABOUT A DEGREE OVERNIGHT DUE TO LAKE ENHANCED
CLOUDS AND FLURRIES STREAMING ACROSS INTERIOR FA. PULLED BACK ON
THE POPS OVER NORTHERN FA EARLY, CONFINING MOST OF THE ACTIVITY TO
SE OF THE FINGER LAKES. BASED ON RAP AND WRFARW WIND PROFILES,
TREND THE SNOW SHOWERS BACK NORTHWARD AS THE ACTIVITY WANES LATE
OVERNIGHT.
750 PM UPDATE...
OPTED TO INCREASE POPS TONIGHT AS LES HAS BLOSSOMED AFTER SUNSET.
HOWEVER SAW NO REASON TO INCREASE SNOW AMOUNTS DUE TO VERY LIGHT
SNOWFALL AND LACK OF SNOW GROWTH. EXTENDED FLURRY ACTIVITY TO THE
SOUTH INTO THE WYOMING VALLEY OF PA.
TEMPS/WINDS IN EXCELLENT SHAPE.
325 PM UPDATE... MULTI-BAND LES REMAINS ACRS PTNS OF CNY LATE THIS
AFTN...ALTHOUGH INTENSITY/ORGANIZATION HAS BEEN COMPROMISED BY
BOTH DECREASING MOISTURE SUPPLY...AND DIURNAL HEATING/BLYR INSTAB.
ALTHOUGH TERRESTRIAL STABILITY WILL INCREASE AGN THIS
EVE...MOISTURE SUPPLY WILL REMAIN FAIRLY SHALLOW...SO MAINLY JUST
FLRYS AND SCTD -SHSN ARE ANTICIPATED OVERNIGHT INTO EARLY
SUN...WITH LITTLE TO NO ADDTNL ACCUMS.
MUCH OF THE DAY SUN SHOULD BE PCPN-FREE...WITH BREAKS OF SUNSHINE
BY AFTN...AS A SFC RIDGE NOSES DOWN FROM ERN CANADA. HIGH TEMPS
WILL REMAIN CHILLY...DESPITE SOME SUN...WITH THE AMS ONLY
SUPPORTING READINGS IN THE UPR 30S TO LWR 40S.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
345 PM UPDATE... THE MAIN SYSTEM OF INTEREST REMAINS THE WV
TRACKING EWD FROM THE OH/TN VLYS TWDS THE MID-ATL COAST LTR SUN
NGT THROUGH MON. NWP CONSENSUS CONTS TO SUGGEST AN UNPHASED SYSTEM
(SEPARATE NRN AND SRN STREAMS) TIL QUITE LATE IN THE EVENT (MON
NGT INTO TUE)...ONCE THE SYSTEM IS ALREADY OFF THE ERN SEABOARD.
ALSO...THE PERSISTENCE OF AN UPR-LVL VORTEX NEAR THE CANADIAN
MARITIMES (CONFLUENT FLOW UNDERNEATH IT)...SHOULD MEAN A FAIRLY
QUICK EXIT TO THE E...ONCE THE CYCLONE REACHES THE MD/VA COASTAL
WATERS.
BOTTOM LN...A QUICK SHOT OF LIFT AND MOISTURE ADVECTION DURG THE
DAY MON...WILL LIKELY BRING A SHORT-LIVED PD OF SNOW. OWING TO
THE PRESENCE OF THE MARITIME UPR LOW MENTIONED ABV...IT APPEARS
THERE IS ONLY SO FAR N THE PCPN SHIELD WILL BE ABLE TO GO...AND
CURRENT MODEL CONSENSUS PAINTS THIS "LINE IN THE SAND" NEAR THE
PA/NY BORDER. POP/QPF/SNOW GRIDS WERE ONLY TWEAKED SLIGHTLY FROM
PERSISTENCE...WITH LIKELY POPS MAINLY CONFINED TO NE PA/SULLIVAN
CNTY...WHERE 1-4" OF SNOW COULD POTENTIALLY FALL. FARTHER N ACRS
CNY...LTL OR NO SNOWFALL SEEMS LIKE THE MOST LIKELY OUTCOME ATTM.
WE`LL CONTINUE TO HIGHLIGHT THIS SYSTEM FOR OUR SRN ZNS IN THE
HWO.
BY TUE...WITH THE COASTAL CYCLONE WELL TO OUR E...A WEAK N TO NW
FLOW WILL RESUME...WITH MORE FLRYS/-SHSN IN THE VICINITY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LTL CHG FROM PREV FCST WITH THE RGN REMAINING UNDER NW FLOW (AFTER
THE DEPARTURE OF THE EARLY WEEK MID ATLC CST STORM)...AND GNRL
UPR LVL TROFFINESS. HPC DATA WAS UTILIZED AS THE BASELINE FCST...BUT
WE ADJUSTED SOME MID-WEEK CLD/POP GRIDS TO INDICATE LOW CHC POPS FOR
-SHSN IN THIS NW FLOW PTRN ACRS CNTRL NY. A VERY GRADUAL MODIFICATION
OF THE COLD TEMPS BY LATE IN THE WORK WEEK.
&&
.AVIATION /05Z SUNDAY THROUGH THURSDAY/...
NW FLOW WILL CONT THRU THE PD BRINGING LAKE MOISTURE INTO THE
REGION. THIS WILL RESULT IN OCNL LGT SNOW SHWRS...ALONG WITH NGT
TIME MVFR CIGS. DAYLIGHT HRS WILL BRING BETTER MIXING AND LL DRY
AIR SO CIGS WILL RETURN TO VFR LVLS. FLOW WILL SUPPORT NW
WINDS...BCMG GUSTY DURING THE DAYLIGHT HRS.
.OUTLOOK...
SUN NGT...PATCHY MVFR CNTRL NY.
MON/MON NGT...MVFR CNTRL NY IN -SHSN...IFR/MVFR NE PA IN SNOW.
TUE/WED/THU/FRI...PATCHY MVFR IN -SHSN MAINLY CNTRL NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJP/MLJ
NEAR TERM...CMG/MLJ
SHORT TERM...MLJ
LONG TERM...
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
512 AM EDT SUN MAR 24 2013
.SYNOPSIS...
BELOW NORMAL TEMPERATURES THROUGH NEXT WEEK. WINTER STORM AFFECTS
THE AREA SUNDAY AND LATE MONDAY...BRINGING MAINLY RAIN SUNDAY...
CHANGING TO ALL SNOW MONDAY NIGHT. UPSLOPE SNOW EVENT FOLLOWS.
&&
.NEAR TERM /THROUGH TONIGHT/...
WHAT A COMPLEX SYSTEM. ON THE POSITIVE SIDE...MODELS AGREE VERY WELL
ON THE MASS AND QPF FIELDS OF THE SYSTEM AFFECTING US THIS PERIOD.
PARENT SURFACE LOW LIFTS NORTHEAST INTO SOUTHERN OHIO AHEAD OF A
DEVELOPING STRONG UPPER LOW OVER THE MID MISSISSIPPI VALLEY...THEN
REDEVELOPS LATER TONIGHT JUST OFF THE MID ATLANTIC COAST AS THE
APPROACHING UPPER SYSTEM TAPS INTO THE GULF STREAM WATERS. LOOKS LIKE
ONE SLUG OF QPF THIS AFTERNOON WITH A LEAD SHORT WAVE AND ANOTHER
TONIGHT WITH THE UPPER LOW ITSELF. HOWEVER...THE THERMAL FIELDS WITH
THE SYSTEM DO NOT AGREE WELL...AND THIS IS CRITICAL TO THE TYPE OF
PRECIP IN A QPF REGIME OF BETWEEN HALF AN INCH AND AN INCH.
NORMALLY...I REPEAT NORMALLY...WITH THE TRACK OF THE PARENT SURFACE
LOW WE WOULD EXPECT A BRIEF PERIOD OF WINTRY MIX TO RAIN IN THE
LOWLANDS AS THE TYPICAL WARM WEDGE IN LOW LEVEL SOUTHEASTERLY FLOW
SURGES AHEAD OF THE LOW. WE WOULD KEEP A WINTRY TYPE PRECIP REGIME
IN THE NORTHERN MOUNTAINS WITH THE TYPICAL UPSLOPE AND COLD AIR
DAMMING. WE WOULD THEN SEE A TRANSITION BACK TO SNOW LATER TONIGHT
AS COLDER AIR WORKS IN ALOFT.
HOWEVER...THE TRACK OF THE UPPER SYSTEM IS EAST RIGHT ACROSS OUR
AREA. THIS PREVENTS THE WARM WEDGE FROM GETTING TOO FAR NORTH THIS
AFTERNOON AS THE HEAVIER PRECIP ARRIVES. THE NAM AND RUC ARE THE
WARM OUTLIER FOR THE WARM WEDGE...WHILE THE GFS AND EURO ARE COLDER.
THIS COLDER SCENARIO APPEARS TO BE DUE TO STRONG UPPER DYNAMICS AND
WET BULBING WHIT THE PRECIP. EVEN THE SREF SHOWS THIS.
AM GOING WITH THE COOLER SCENARIO. YES...THE MAV/LAMP TEMP GUIDANCE
CURIOUSLY SHOW HIGHS IN THE 40S FOR MUCH OF THE LOWLANDS TODAY...BUT
THIS IS DISCOUNTED BY THE GUIDANCE NOT SEEMING TO ACCOUNT FOR WET
BULB COOLING. SO WILL ACTUALLY USE THE COOLER NAM SURFACE TEMPS BUT
THE GFS/EURO AND SREF COOLER TEMPS ALOFT.
ALL THIS PANS OUT TO TEMPS TODAY REMAINING IN THE 30S ACROSS THE
MOST OF THE LOWLANDS...WHILE BELOW FREEZING TEMPS OCCUR IN THE
NORTHERN MOUNTAINS. THIS WILL BE COLD ENOUGH FOR ALL SNOW NORTHERN
MOUNTAINS...SNOW WITH MIXED RAIN AND SLEET ACROSS THE FAR
NORTH...AND BRIEF WINTRY MIX TO RAIN ELSEWHERE. WITH THE AMOUNT OF
QPF...COULD BE HEAVY WET SNOW ACROSS THE FAR NORTH. THUS...ISSUED A
WINTER WEATHER ADVISORY FOR THE AREA LATER THIS AFTERNOON AND
ESPECIALLY TONIGHT WITH THE SECOND QPF SLUG. WINTER STORM WARNING
REMAINS IN EFFECT FOR THE NORTHERN MOUNTAINS.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
LOW PRESSURE SYSTEM EXITS TO THE EAST...ONLY TO HAVE CYCLONIC FLOW
REINFORCED BY A SECONDARY TROUGH SWINGING THROUGH THE TENNESSEE
VALLEY INTO THE MID ATLANTIC. IN THE LOWER LEVELS...FLOW WILL TURN
AROUND TO THE NORTHWEST THAT WILL EVENTUALLY TAP INTO SOME GREAT
LAKES MOISTURE. COLD POOL ALOFT WILL SETTLE INTO THE AREA...AND WILL
NOT RELINQUISH ITS GRIP ALL THE WAY INTO MID WEEK...WITH 850MB
TEMPERATURES VARYING FROM -7C TO -10C. IN THE END...THIS RESULTS IN
POPS FOR THE BULK OF THE SHORT TERM FORECAST ENHANCED BY THE
AFOREMENTIONED SECONDARY TROUGH AXIS MONDAY EVENING INTO
TUESDAY...AND THEN THE CONVECTIVE NATURE OF THE NORTHWEST FLOW INTO
WEDNESDAY.
UNDERCUT THE GUIDANCE FOR THE DAYTIME MAXIMUM TEMPERATURES GIVEN THE
CLOUD COVER...PRECIPITATION...NORTHWESTERLY FLOW...AND COLD POOL
ALOFT. WITH THAT BEING SAID...GIVEN THE TIME OF YEAR...BEST CHANCE
FOR SNOW ACCUMULATIONS WILL BE DURING THE OVERNIGHT HOURS. HAVE
DAYTIME TEMPERATURES CLIMBING ABOVE FREEZING IN MOST
CASES...ALTHOUGH THE MOUNTAINS WILL HOVER AROUND FREEZING OR STAY
BELOW IN THE CASE OF THE HIGHER ELEVATIONS OF THE NORTHEAST
MOUNTAINS. SO...EXPECT SOME MELTING DURING THE DAY...WITH SUN ANGLE
AND LONGER DAYS THAN NIGHTS ALSO CONTRIBUTING TO THIS EQUATION.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
USED THE ECMWF ENSEMBLE MEAN THROUGH THE PERIOD. SOME UPSLOPE SNOW
SHOWERS REMAIN A POSSIBILITY TUESDAY NIGHT INTO EARLY THURSDAY. HIGH
PRESSURE THEN BUILDS IN FOR THURSDAY NIGHT AND FRIDAY. A LOW
CONFIDENCE SYSTEM THEN SLIDES SOUTH OF THE AREA FRIDAY NIGHT AND
SATURDAY...CAUSING SOME SMALL POPS OVER OUR FORECAST AREA.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
06Z SUNDAY THRU 06Z MONDAY...
VFR THRU 12Z WITH INCREASE IN MID/HI CLDS OVERNIGHT.
AFTER 12Z CIGS WITH ASSOC PRECIP WILL BE RAPIDLY PUSHING
NORTHEASTWARD ACROSS THE AREA...WITH MUCH OF THE AREA FALLING
THROUGH MVFR CIGS AND INTO IFR CIGS AFTER PRECIP BEGINS. A MIX OF
RA/SN FOR KHTS-KCRW-KBKW 15 TO 18Z WITH SOME IFR VSBY WHERE PCPN
STAYS MAINLY SN. A SWITCH TO RA IN AFTN CENTRAL AND SOUTHERN LOW
LANDS WITH PERHAPS SOME IMPROVEMENT IN CIGS INTO MVFR. AS PCPN
PUSHES N...IFR CONDITIONS IN MAINLY SN DEVELOP AFTER 18Z FOR N TAF
SITES...ESPECIALLY NORTHERN AND CENTRAL MOUNTAINS.
AFTER 00Z...IFR TO MVFR. WINTRY PRECIP CONTINUES NORTHERN AND
CENTRAL MOUNTAINS...WHILE MIXED PRECIP CHANGES TO SNOW BY 06Z
ELSEWHERE.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z MONDAY...
FORECAST CONFIDENCE...MED TO HIGH.
ALTERNATE SCENARIOS: TIMING OF SUB-VFR CIGS AND ONSET OF PRECIP MAY
VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE SUN 03/24/13
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15
CRW CONSISTENCY H H H H H H H M M H H H
HTS CONSISTENCY H H H H H H H H H M H H
BKW CONSISTENCY H H H H H H L M M M M M
EKN CONSISTENCY H H H H H H H H H H L L
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 06Z MONDAY...
IFR CONDITIONS POSSIBLE IN RAIN AND WINTRY MIX INTO SUNDAY NIGHT
AND THEN MAINLY SNOW EARLY MONDAY MORNING THROUGH MONDAY NIGHT.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 11 AM EDT
MONDAY FOR WVZ010-011-020-031-032-039-040.
WINTER STORM WARNING FROM NOON TODAY TO 2 PM EDT TUESDAY FOR
WVZ038-046-047.
OH...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 11 AM EDT
MONDAY FOR OHZ066-067-075-076-084.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JMV/26
NEAR TERM...JMV
SHORT TERM...26
LONG TERM...RPY
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1146 PM CDT SAT MAR 23 2013
.UPDATE...ADDED AVIATION SECTION FOR 06 TAF`S.
&&
.AVIATION...BNA/CKV/CSV...TRICKY WX SITUATION SHAPING UP DURING
THE NEXT 18 HRS OR SO AS MOISTURE GRADUALLY SPREADS ACROSS
MIDDLE TENNESSEE AHEAD OF A STRONG LOW PRESSURE SYSTEM. EXPECTING
MAINLY LIGHT RAIN WITH LOW CIGS DEVELOPING OVERNIGHT AS THE
SURFACE LOW RACES NEWD TOWARD MIDDLE TENNESSEE. FORECAST LOW TRACK
ACTUALLY BISECTS THE MID STATE ON SUNDAY WHILE DRAGGING A COLD
FRONT ACROSS THE AREA DURING THE AFTERNOON. DEEPEST MOISTURE
APPEARS TO PULL OUT AHEAD OF THE FRONT, BUT, GIVEN THE ENHANCED
FORCING BY THE LOW ITSELF, THERE MAY BE ENOUGH LEFTOVER LOW-LEVEL
MOISTURE TO KICK OFF A LINE OF CONVECTION ALONG THE FRONT ITSELF.
ALSO LOOK FOR WINDS TO INCREASE DRAMATICALLY DURING THE AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 929 PM CDT SAT MAR 23 2013/
MESOSCALE UPDATE...
AT 915PM...RADAR INDICATED AREAS OF MODERATE RAIN ENTERING
SOUTHERN MIDDLE TN. 00Z SOUNDING ANALYSIS DOES SHOW A CONSIDERABLE
INVERSION AT THE 800 MB LEVEL WITH STEEP LAPSE RATES ABOVE THE
INVERSION. SHORT TERM MODELS VARY ON DEPICTING HOW TONIGHTS
ACTIVITY WILL EVOLVE.
THE NAM IS DEFINITELY THE MOST AGGRESSIVE WITH THUNDER
POSSIBILITIES...DEPICTING STRONG LOW TO MID LEVEL OMEGA FIELDS
DRAPED FROM WESTERN KY THROUGH NORTHEAST AL. THIS IN CONJUNTION
WITH AN INTENSIFYING LLJ OF 45-50 KTS OVER NORTHERN AL. STRONG
SPEED CONVERGENCE AT THE 850 MB LEVEL OVER SOUTH CENTRAL TN
APPEARS TO BE THE METHOD OF FORCING THAT COULD PRODUCE SOME STRONG
THUNDERSTORMS OVERNIGHT FOR AREAS IN THE SOUTHERN THIRD OF THE
CWA. SMALL HAIL AND SOME STRONG WINDS WOULD BE THE MAIN THREATS.
OTHER HI RESOLUTION MODELS...WHILE STILL BRINGING WIDESPREAD RAIN
THROUGH MIDDLE TN BY 08Z...ARE LESS ROBUST ON THE FORCING. WHILE
THE SFC LOW PASSES ACROSS CENTRAL AL...AND THE LLJ DOES
INTENSIFY...RUC/HRRR DEPICTS WEAKER
INSTABILITY...CONVERGENCE...AND BULK SHEAR. THUS RESULTING IN A
WIDESPREAD...AND HEAVY AT TIMES...RAIN EVENT.
IF STRONG STORMS WERE TO DEVELOP FOR MIDDLE TN...STILL BELIEVE THE
THREAT WOULD BE IN THE SOUTHERNMOST COUNTIES...BUT FOR NOW...FEEL
THE MODERATE TO HEAVY RAIN SCENARIO WITH SOME THUNDER POSSIBLE
WILL STILL BE VALID.
PREV DISCUSSION... /ISSUED 649 PM CDT SAT MAR 23 2013/
UPDATE...ADDED AVIATION SECTION FOR 00Z TAF`S.
AVIATION...BNA/CKV/CSV...CONDITIONS SLOWLY DETERIORATING ACROSS
MIDDLE TENNESSEE THIS EVENING AS A SURFACE LOW APPROACHES FROM
THE SW. LOOK FOR LIGHT RAIN DURING THE EVENING WITH CIGS
EVENTUALLY LOWERING BELOW 3 KFT. WINDS WILL REMAIN LIGHT
OVERNIGHT, EVEN AS SHOWERS INCREASE IN INTENSITY AND CIGS DROP TO
IFR. RUC SOUNDINGS SHOWING NO SURFACED-BASED OR ELEVATED
INSTABILITY, SO WILL LEAVE TS OUT OF THE TAF`S. EXPECT WINDS TO
SHIFT AROUND TO THE SW ON SUNDAY AND INCREASE DRAMATICALLY AS THE
LOW BISECTS THE MID STATE.
PREV DISCUSSION... /ISSUED 242 PM CDT SAT MAR 23 2013/
DISCUSSION...
SHOWERS AND A FEW THUNDERSTORMS HAVE SPREAD AS FAR EAST AS NORTH
MISSISSIPPI AND INTO THE FAR SOUTHWEST CORNER OF TENNESSEE AROUND
MEMPHIS. GULF COAST SYSTEM WILL WORK ALONG COAST TONIGHT WITH
INVERTED TROUGH EXTENDING UP INTO TENNESSEE THROUGH THE OVERNIGHT
AS LOW LIFTS NORTHWARD LATE NIGHT INTO NORTH ALABAMA BY 12Z
SUNDAY. IT LOOKS LIKE A PRETTY GOOD ROUND OF RAIN LIFTING NORTH
THROUGH ALABAMA AND INTO MIDDLE TENNESSEE AFTER MIDNIGHT. I EXPECT
TO HEAR A LITTLE THUNDER WITH GOOD DOWNPOURS WITH THIS IN THE LATE
NIGHT HOURS AS IT MOVES THROUGH THE AREA. SURFACE LOW LIFTS UP
INTO MIDDLE TENNESSEE DURING THE DAY SUNDAY SO AM EXPECTING MORE
RAIN WITH A FEW THUNDERSTORMS DURING THE DAY ON SUNDAY. SURFACE
LOW LIFTS OUT TO THE NORTHEAST AND INTO EASTERN KENTUCKY BY
MIDNIGHT SUNDAY NIGHT WHILE UNDERGOING CYCLOGENSIS WITH PRECIP
HANGING BACK OVER MIDDLE TENNESSEE AS A MIX OF RAIN AND SNOW
SUNDAY NIGHT AS TEMPS FALL INTO THE LOWER 30S MOST AREAS. ON
MONDAY PRECIP STILL LINGERING IN THE FORM OF A MIX OVER SOUTHWESTERLY
AREAS AND LIGHT SNOW NORTHEAST HALF WITH HIGHS MOSTLY IN THE UPPER
30S. MONDAY NIGHT LOOKS HAVE THE BEST CHANCE FOR SEEING A LITTLE
ACCUMULATION HERE IN THE MID STATE. I THINK WE COULD BE LOOKING AT
AN INCH IN FENTRESS AND CUMBERLAND COUNTIES WEST TOWARD PUTNAM
COUNTY AS RESIDUAL MOISTURE GETS SQUEEZED OUT WITH A LITTLE HELP
FROM OROGRAPHY. LOOKS LIKE TEMPS WILL BE BELOW NORMAL AT LEAST
THROUGH NEXT FRIDAY WITH HIGHS ON SATURDAY IN THE 60S WHICH IS
JUST ABOUT NORMAL FOR THIS TIME OF THE YEAR.
CLIMATE...TEMPS ARE AVERAGING NEARLY 4 DEGREES BELOW NORMAL SO FAR THIS
MARCH. WHAT A CONTRAST WITH MARCH OF 2012 WHICH WAS THE WARMEST MARCH
ON RECORD. RAINFALL HAS TOTALED 3.20 INCHES WHICH IS CLOSE TO NORMAL
THROUGH THE THIRD WEEK OF MARCH.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
ROSE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1142 PM CDT SAT MAR 23 2013
.SHORT TERM...TONIGHT THROUGH TUESDAY
321 PM CDT SAT MAR 23 2013
THE MAIN FOCUS THROUGH EARLY NEXT WEEK IS WITH THE SNOW THAT WILL
MOVE IN OVERNIGHT AND END SUNDAY NIGHT.
BROAD MID LEVEL TROUGHING IN PLACE ACROSS THE EASTERN ROCKIES AND
WESTERN PLAINS WITH A NUMBER OF TROUGHS EMBEDDED WITHIN THIS FLOW.
THE FIRST MID LEVEL SHORT WAVE TROUGH HAS PROPAGATED ACROSS IOWA
AND SOUTHERN MINNESOTA AND HAS BROUGHT AN INCREASE IN HIGH LEVEL
CLOUD COVER WITH IT. THERE IS TOO MUCH DRY LOW LEVEL AIR IN PLACE
RIGHT NOW FOR THIS FEATURE TO PRODUCE ANY PRECIPITATION...SO THE
FOCUS THEN GOES TO THE NEXT...MORE VIGOROUS CLOSED MID LEVEL LOW
THAT CURRENTLY IS IN EASTERN COLORADO AND SITS AT THE BASE OF THE
LONG WAVE TROUGH. THIS FEATURE WILL TAKE A DUE EAST TRACK ACROSS
THE MID MISSISSIPPI VALLEY REGION TONIGHT INTO TOMORROW. THIS
TROUGH WILL PROVIDE THE MAIN LIFTING MECHANISM FOR THE NEXT PERIOD
OF SNOW THAT WILL MOVE IN OVERNIGHT AND LAST THROUGH MUCH OF THE
DAY. AT THE SURFACE...BROAD RIDGING EXTENDS ACROSS CENTRAL CANADA
WITH A LOW ANALYZED OVER NEW MEXICO. IN BETWEEN THESE TWO
FEATURES...IT IS MAINLY JUST A WEST TO EAST PRESSURE GRADIENT WITH
AN INVERTED TROUGH EXTENDING NORTH OUT OF THE LOW ACROSS EASTERN
COLORADO. THE 23.12Z SUITE OF MODEL GUIDANCE ALL APPEAR TO HAVE
INITIALIZED WELL...THOUGH THE 23.12Z TO 23.18Z RAP IS WAY OFF ON
THE SNOW DEPTH WHICH CREATES WAY TOO WARM OF TEMPERATURES IN THE
AREAS WHERE THERE IT THINKS THERE IS NO SNOW PACK.
AS THE CLOSED MID LEVEL LOW TRACKS TO THE EAST TONIGHT...THE
INVERTED SURFACE TROUGH WILL BECOME A LITTLE MORE AMPLIFIED AND
BECOME THE MAIN LOW LEVEL CONVERGENCE FEATURE THAT THE SNOW WILL
BECOME FOCUSED AROUND. THE DEEPER LIFT WILL COME IN AHEAD OF THE
TROUGH WITH MUCH OF THE HIGHEST OMEGA SHOWING UP IN THE 600-500MB
RANGE. WITH THE OVERALL LIFT NOT BEING VERY DEEP...THE CONCERN IS
WITH A DRY LAYER BETWEEN 800-600MB THAT THIS LIFT WILL HAVE TO
OVERCOME...PARTICULARLY THE FARTHER NORTH AND EAST YOU GET FROM
THE CORE OF THE SYSTEM. THE 23.12Z NAM/GFS BUFKIT SOUNDINGS DO
SHOW A DECENT SIZED DENDRITIC GROWTH ZONE THAT IS ABOUT 150MB DEEP
FOR MUCH OF THE EVENT...BUT THE LIFT IS ONLY IN THAT SECTION OF
THE SOUNDING FOR A BRIEF PERIOD. ANY DENDRITES THAT FALL THROUGH
THE DRY LAYER WILL LIKELY SHRINK AS THEY MAKE IT THROUGH ON THEIR
WAY DOWN THE GROUND. OVERALL...FAIRLY CONFIDENT THAT AREAS ALONG
AND WEST OF THE MISSISSIPPI RIVER WILL SEE A LIGHT ACCUMULATING
SNOW FROM LATE TONIGHT THROUGH MUCH OF THE DAY. GENERALLY HAVE
ABOUT 1 TO 2 INCHES RUNNING ACROSS NORTHEAST IOWA AND A PORTION OF
SOUTHEAST MINNESOTA WITH LESSER AMOUNTS ALONG AND NORTHEAST OF THE
MISSISSIPPI RIVER. AS THE NORTHERLY LOW TO MID LEVEL FLOW KICKS IN
SUNDAY NIGHT...THE 800-600MB WEDGE OF DRY AIR GETS PULLED BACK
DOWN TO THE SOUTH AND SHOULD BRING AN END TO THE SNOW FAIRLY
QUICKLY IN THE EVENING.
BEYOND THIS...WE STAY IN LOW LEVEL CYCLONIC FLOW WITH WEAK RIDGING
ALOFT IN THE WAKE OF THE TROUGH. MAY STILL SEE SOME FLURRIES ON
MONDAY DUE TO SOME WEAK LOW LEVEL LIFT DUE TO THE CYCLONIC FLOW
WITH THE SATURATED PORTION OF THE LOW LEVEL PROFILE BEING COLD
ENOUGH WHERE ICE WILL BE PRESENT. OTHERWISE THE CHALLENGES WILL BE
WITH TEMPERATURES AND CLOUD COVER WITH SOME CLEARING POSSIBLE
GOING INTO TUESDAY.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
321 PM CDT SAT MAR 23 2013
THE GOOD NEWS IN THE LONG TERM PERIOD IS THAT IT APPEARS THE MID LEVEL
TROUGH STARTS TO BREAK DOWN AND PUSH TO THE EAST WITH GRADUAL MID
LEVEL RIDGING DEVELOPING ACROSS THE WESTERN HALF OF THE US. WHILE
THE UPPER MISSISSIPPI RIVER VALLEY IS STILL IN GENERAL NORTHWEST
FLOW ALOFT...THE LOW LEVEL FLOW BECOMES MORE SOUTHWESTERLY WITH
850MB TEMPERATURES SLOWLY INCREASING FROM -10C TUESDAY NIGHT TO
AROUND 0C BY FRIDAY. PRECIPITATION WISE...THERE IS SOME SUGGESTION
THAT THE VORT MAX CURRENTLY OVER THE WESTERN PART OF HUDSON BAY
EVENTUALLY GETS CAUGHT IN THE NORTHWEST FLOW ALOFT AND PULLS IT
DOWN INTO THE UPPER GREAT LAKES BY FRIDAY NIGHT. WITH MUCH OF THE
FORCING FROM THIS SYSTEM LIKELY STAYING TO THE NORTHEAST...HAVE
KEPT THE FORECAST DRY FROM MID WEEK INTO SATURDAY.
&&
.AVIATION...THROUGH 06Z MONDAY
1141 PM CDT SAT MAR 23 2013
A TROUGH OF LOW PRESSURE EXTENDING NORTH-SOUTH THROUGH KLSE IS
FORECAST TO INTENSIFY THIS MORNING...NEAR 12Z...AS A WAVE IN THE
UPPER LEVELS OF THE TROPOSPHERE APPROACHES IT. THIS WILL
EVENTUALLY PRODUCE SNOW...ONCE DRIER AIR IN THE LOWER LEVELS IS
OVERWHELMED. CURRENT THINKING REMAINS THE SAME THAT KRST HAS THE
BETTER CHANCE OF SEEING THIS SNOW...ALONG THE TRACK OF THAT
WAVE...WITH VISIBILITIES DROPPING TO MVFR BY 12Z AND IFR SHORTLY
THEREAFTER. CEILINGS SHOULD FALL AT LEAST TO MVFR. SINCE THE
FORCING LOOKS WEAK AND THE LOW LEVEL FLOW IS A DRIER NORTHEAST
DIRECTION...DID NOT INTRODUCE ANY IFR CEILINGS. KLSE IS EITHER ON
OR TO THE EAST SIDE OF THE TROUGH...SO THE EAST TO NORTHEAST FLOW
OF DRY AIR AT BOTH THE LOWER AND MID LEVELS OF THE TROPOSPHERE
WILL HAVE MORE OF AN INFLUENCE. AS SUCH...KEPT CEILINGS VFR FOR
NOW AND MAINTAINED ONLY AN MVFR PERIOD OF VISIBILITY BETWEEN
15-21Z. IT APPEARS THAT THE SNOW SHOULD END AT BOTH TAF SITES BY
00Z AS THE TROUGH SWINGS SOUTHWEST. UNSURE EXACTLY HOW CEILINGS
WILL PLAY OUT ONCE THE SNOW ENDS. FOR NOW HELD THEM MAINLY
STEADY...VFR AT KLSE AND MVFR AT KRST. HOWEVER...IT IS POSSIBLE
SOME CLEARING MAY TRY TO WORK IN DEPENDING ON HOW MUCH DAYTIME
MIXING AND DRYING OCCURS DURING THE AFTERNOON OVER NORTHERN
WISCONSIN. PARTIAL CLEARING WOULD BE MORE LIKELY AT KLSE BEING
CLOSER TO THE SOURCE REGION OF DRIER AIR.
TOTAL SNOWFALL AMOUNTS AGAIN LOOK LIGHT...MAINLY AN INCH OR
LESS...AND PERHAPS ONLY A TRACE AT KLSE. WITH MOST OF THE SNOW
FALLING DURING THE DAY...A LOT OF IT IS LIKELY TO MELT TOO WITH
THE HIGH SUN ANGLE NOW.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
321 PM CDT SAT MAR 23 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
931 AM MDT SUN MAR 24 2013
.UPDATE...
&&
.SHORT TERM...A DISTURBANCE IN NW FLOW ALOFT WILL MOVE ACROSS THE
AREA THIS AFTN INTO THE EARLY EVENING HOURS AS A BNDRY MOVES INTO
NERN CO ENHANCING UPSLOPE FLOW ALONG THE FRONT RANGE. LATEST DATA
DOES SHOW SOME MID LVL QG ASCENT THIS AFTN INTO THE EARLY EVENING
HOURS WITH LAPSE RATES IN AND NR THE FOOTHILLS AROUND 9 C/KM.
LATEST RAP SOUNDINGS BECOME MOIST ADIABATIC AS WELL. THUS WOULD
EXPECT SNOW SHOWER ACTIVITY TO INCREASE THIS AFTN AND CONTINUE
THRU THE EARLY EVENING HOURS. BOTH THE RAP AND HRRR ARE SHOWING
SOME DECENT SNOW AMOUNTS IN THE FOOTHILLS WEST AND SOUTHWEST OF
DENVER WITH AMOUNTS OF 4 TO 8 INCHES WITH UP TO 4 INCHES IN THE
WRN SUBURBS. FURTHER EAST AMOUNTS ARE IN THE 1 TO 2 INCH RANGE.
HAVE BUMPED UP SNOW AMOUNTS SOME BUT NOT QUITE AS HIGH AS THE RAP
IS SHOWING.
.AVIATION...WINDS SHOULD GRADUALLY BECOME MORE NNE BY 18Z AND
CONTINUE THRU THE EARLY EVENING HOURS. BEST CHC OF SNOW LOOKS TO
BE IN THE 23Z-03Z TIMEFRAME WHEN UP TO AN INCH OF SNOW MAY OCCUR
AT DIA. AT THIS TIME IT APPEARS HEAVIER AMOUNTS WILL STAY TO THE
WEST AND SW OF DIA WITH BJC AND APA SEEING UP TO 3 INCHES POSSIBLY.
CEILINGS AND VISIBILITIES MAY DROP DOWN TO IFR BETWEEN 23Z AND
03Z WITH SOME LIFR AT BJC AND APA. SNOW THREAT SHOULD GRADUALLY
DECREASE AROUND 03Z AT DIA AND BJC BUT MAY LINGER THROUGH 05Z AT
APA.
&&
.PREV DISCUSSION... /ISSUED 344 AM MDT SUN MAR 24 2013/
SHORT TERM...NORTHWEST FLOW ALOFT WILL BE OVER THE STATE TODAY
AS AN UPPER LOW SPINS OVER THE GREAT PLAINS. A DISTURBANCE MOVING
AROUND THIS LOW WILL PASS OVERHEAD TODAY TO INCREASE CHANCES FOR
SNOW AGAIN TODAY. A SLIGHT SURGE FROM THE NORTH TURNING WINDS
UPSLOPE OVER THE PLAINS...ALONG WITH SLIGHT INSTABILITY IN THE
AIRMASS TODAY AND JUST ENOUGH MOISTURE WILL AID IN THE LIKELY
CHANCES FOR SNOW ACCUMULATION. THE MOUNTAINS ARE ALREADY SEEING
LIGHT SNOW EARLY THIS MORNING IN THE FAVORED NORTHWEST FLOW...THEN
SNOWFALL RATES WILL BE INCREASING THROUGH THE DAY AS THE
DISTURBANCE PASSES. A TOTAL OF 2 TO 5 INCHES WILL LIKELY FALL
THROUGH THE DAY AND INTO THE NIGHT...WITH THE HIGHER AMOUNTS FOUND
NORTH OF I-70 ALONG WEST FACING SLOPES. AS FOR THE PLAINS...THE
SURGE FROM THE NORTH IS EXPECTED LATE THIS MORNING. THIS WILL AID
IN GETTING SHOWERS TO BEGIN MORNING BY EARLY AFTERNOON. THERE MAY
BE A BIT OF DOWNSLOPING TO FIGHT WITH NORTHWEST FLOW
ALOFT...HOWEVER WITH THE INSTABILITY AND THE COMPLEXITIES THAT
ALWAYS SHOW WITH NORTHWEST FLOW...SHOULD SEE LIGHT SNOW OVER MOST
OF THE PLAINS WITH SLIGHTLY HIGHER AMOUNTS OVER THE URBAN CORRIDOR
DOWN TO THE PALMER DIVIDE. TOTAL SNOWFALL AMOUNTS ARE EXPECTED TO
BE QUITE LIGHT COMPARED TO WHAT WE JUST EXPERIENCED...GENERALLY
BELOW 2 INCHES.
TEMPERATURES WILL REMAIN COLDER THAN NORMAL BY AROUND 30 DEGREES
TODAY. READINGS IN THE 20S AGAIN FOR THE PLAINS AND IN THE TEENS
FOR THE MOUNTAINS. MINIMUM TEMPERATURES WILL BE COLD AGAIN AS WELL
WITH SINGLE DIGIT TO BELOW ZERO READINGS. LIGHT WINDS WILL
PREVAIL.
LONG TERM...SUBSIDENCE WILL INCREASE ACROSS THE FORECAST AREA
MONDAY WITH DRIER AIR TAKING HOLD. THERE IS STILL A LITTLE
MOISTURE IN/NEAR THE MOUNTAINS LINGERING INTO MONDAY MORNING...AND
A BIT OF SHALLOW INSTABILITY IN THE MOUNTAINS DURING THE
AFTERNOON...SO WILL KEEP SOME LOW POPS FOR THAT. OTHERWISE LOOK
FOR SOME SUNSHINE TO RETURN. HOWEVER...TEMPERATURES WILL REMAIN
MUCH BELOW NORMAL AND WILL HAVE A HARD TIME EVEN APPROACHING THE
FREEZING MARK. LOWS MONDAY NIGHT SHOULD DROP INTO THE SINGLE
DIGITS AGAIN ON THE PLAINS WITH MOSTLY CLEAR SKIES...WITH BELOW
ZERO READINGS IN THE HIGH COUNTRY.
BY TUESDAY...FLOW ALOFT BECOME MORE WESTERLY WHICH WILL BEGIN A
SLOW WARMING TREND. IT WILL TAKE A FEW DAYS TO MELT THE SNOW
COVER...SO THE GOING CONSERVATIVE TEMPERATURE FORECAST THROUGH MID
WEEK IS GOOD ESPECIALLY CONSIDERING THE LOW LEVEL EASTERLY FLOW
WITH COLD HIGH PRESSURE RESIDING OVER THE CENTRAL PLAINS.
MEANWHILE...THE CURRENT UPPER LOW SPINNING IN THE EASTERN PACIFIC
GETS CAUGHT UP IN THE WESTERLY FLOW AND GRADUALLY SHEARS OUT.
HOWEVER...THERE IS ENOUGH MOISTURE TO WARRANT SOMEWHAT HIGHER POPS
IN THE MOUNTAINS BEGINNING TUESDAY AND CONTINUING INTO WEDNESDAY.
THE CHANCE FOR ANY PRECIPITATION SPILLING ONTO THE PLAINS IS QUITE
LOW GIVEN THE WESTERLY FLOW ALOFT SO HAVE KEPT THE LOWER
ELEVATIONS DRY FOR NOW.
BY THURSDAY...SOME AMPLIFICATION OF THE UPPER RIDGE IS EXPECTED SO
THAT SHOULD BE A MAINLY DRY DAY. THERE IS CONSIDERABLE UNCERTAINTY
WITH REGARD TO EVOLUTION OF THE WEATHER PATTERN LATE IN THE WEEK
INTO NEXT WEEKEND. THERE IS POTENTIAL FOR A DECENT SURGE AT SOME
POINT SO IT SEEMS PRUDENT TO MENTION COOLER TEMPERATURES AND A
SLIGHT CHANCE OF SHOWERS BY THE WEEKEND.
AVIATION...WITH MOSTLY CLEAR SKIES EARLY THIS MORNING...THERE
WILL STILL BE A POSSIBILITY OF PATCHY FOG AT THE AIRPORTS UNTIL A
COUPLE HOURS AFTER SUNRISE. HOWEVER DRIER DEWPOINTS MOVING IN MAY
HELP KEEP IT FROM FORMING. WILL KEEP THE VCFG IN THE TAFS AT THIS
POINT AND MONITOR OBSERVATIONS...WEBCAMS AND SATELLITE. A PUSH
FROM THE NORTH TODAY WILL HELP TURN SURFACE WINDS SLIGHTLY UPSLOPE
BY NOON. WITH NORTHWEST FLOW ALOFT...SLIGHT INSTABILITY AND ENOUGH
MOISTURE AROUND...MAY SEE LIGHT SNOW SHOWERS AS EARLY AS 22Z WITH
A SHOWERS LIKELY TURNING TO MORE WIDESPREAD SNOW THROUGH 03Z. IFR
CONDITION EXPECTED UNDER THE SNOW WHERE IT DEVELOPS. WILL
CONTINUE TO MONITOR THE DEVELOPMENT OF THIS DISTURBANCE.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BARJENBRUCH
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1036 AM EDT SUN MAR 24 2013
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 322 AM EDT SUN MAR 24 2013
A STRENGTHENING LOW PRESSURE SYSTEM WILL LIFT NORTHEAST ACROSS
EASTERN KENTUCKY TODAY AND THIS EVENING BEFORE MOVING INTO SOUTHERN
OHIO OVERNIGHT. THIS SYSTEM IS EXPECTED TO BRING SIGNIFICANT WET
SNOW ACCUMULATION TO CENTRAL INDIANA ESPECIALLY CONSIDERING IT IS
LATE MARCH. SNOW ACCUMULATION WILL BE HEAVIEST LATE THIS AFTERNOON
AND TONIGHT. SCATTERED SNOW SHOWERS WILL LINGER BEFORE HIGH PRESSURE
GRADUALLY BUILDS IN FROM THE PLAINS BRINGING DRY WEATHER AND
GRADUALLY WARMING TEMPERATURES THROUGH LATE WEEK. BY
SATURDAY...HIGHS COULD BE NEAR NORMAL MOSTLY IN THE 50S WITH RAIN
SHOWER CHANCES IN SOUTHERLY FLOW ON THE BACK SIDE OF HIGH PRESSURE.
&&
.NEAR TERM /REST OF TODAY AND TONIGHT/...
ISSUED AT 1026 AM EDT SUN MAR 24 2013
AT 10 AM LOW PRESSURE OF JUST UNDER 1000 MB WAS CENTERED NEAR THE
MISSOURI BOOT HEEL. RADAR SHOWS MOST SNOWFALL HAS ENDED MOMENTARILY
ACROSS CENTRAL INDIANA WITH MODERATE TO HEAVY SNOW ACROSS WESTERN
AND SOUTHERN ILLINOIS AND RAIN SOUTH OF THERE. SLEET HAS ALSO BEEN
REPORTED WITHIN THE PAST COUPLE HOURS. TEMPERATURES IN THE AREA
RANGE FROM THE UPPER 20S IN THE NORTHEAST TO THE MIDDLE 30S ACROSS
THE SOUTH.
FOR THE UPDATE LEANED HEAVILY ON HRRR FOR TIMING OF RETURN OF
PRECIP BUT SPED UP BY A COUPLE HOURS BASED ON COMPARISON WITH
CURRENT RADAR ECHOES. WITH TRACK OF 6Z NAM JUMPING NORTH AND RAP
OVERDOING WARM INTRUSION COMPARED TO OBSERVATIONS USED SREFS AND
GFS FORECAST SOUNDINGS FOR PRECIP TYPE. ADDED SOME TIMING TO THE
POPS FOR THE REST OF THE DAY TO INDICATE A LULL IN ACTIVITY DURING
THE MORNING WITH POPS RAPIDLY INCREASING FROM THE WEST IN THE 11
AM TO NOON TIME FRAME AND OVERSPREADING THE AREA FROM THERE.
FORECAST SOUNDINGS INDICATE SOME POTENTIAL FOR SLEET TO MIX IN AS
FAR NORTH AS THE I-70 CORRIDOR SO ADDED A CHANCE FOR SLEET THERE
THROUGH MUCH OF THE AFTERNOON. MAINTAINED A MIX OF RAIN AND SNOW
IN THE SOUTH WITH THE AFOREMENTIONED SLEET POTENTIAL. SOUNDINGS
INDICATE A CHANGEOVER TO ALL SNOW BY AROUND 22-23Z. SOME CONCERN
THAT MIX OF RAIN AND SLEET WITH THE SNOW COULD DROP SNOWFALL
ACCUMULATION IN THE SOUTH DURING THE TODAY PERIOD BY A DECENT
AMOUNT...BUT THIS IS COUNTERACTED BY SIGNIFICANT SNOWFALL RATES
UPSTREAM IN SOUTHWESTERN AND CENTRAL ILLINOIS OF 1-3 INCHES PER
HOUR AND THUS MAKING NO APPRECIABLE CHANGES TO SNOWFALL AMOUNTS AT
THIS TIME. WITH OBSERVATIONS OF A FEW LIGHTNING STRIKES UPSTREAM
AND SYSTEM ONLY PROGGED TO STRENGTHEN AS IT ARRIVES ADDED A
SLIGHT CHANCE FOR THUNDER SOUTH OF INTERSTATE 70 AS WELL.
PREVIOUS DISCUSSION FOLLOWS...
MAIN CHALLENGE TODAY WILL BE PRECIPITATION TIMING AND TYPE
ALONG WITH SNOW AMOUNTS AS MODELS ARE NOW COMING TOGETHER NICELY
IN HANDLING THE STRENGTH AND LOCATION OF LOW PRESSURE SYSTEM THAT
IS PROGGED TO LIFT NORTHEAST FROM THE SOUTHERN STATES TO EAST
CENTRAL KENTUCKY BY 00Z MONDAY. STRONG UPPER LOW MOVING TO NEAR THE
CONFLUENCE OF THE OHIO AND MISSISSIPPI RIVERS ALONG WITH A VIGOROUS
140 PLUS KNOT JET ACROSS THE TENNESSEE VALLEY WILL RESULT IN THE
AFOREMENTIONED SURFACE LOW DEEPENING TO LESS THAN 995 MILLIBARS BY
EVENING AND RESULT IN MODERATE TO HEAVY SNOW BY LATE AFTERNOON.
WITH MODELS TRENDING A LITTLE BIT FURTHER SOUTH THAN PREVIOUS
RUNS...HEAVIEST SNOW TODAY SHOULD BE ALONG AND SOUTH OF INTERSTATE
70 AND TO THE NORTH OF THE MIXED AREA. THIS AREA WILL ALSO BE NEAR
ELONGATED 850 MILLIBAR FRONTOGENESIS AND INSTABILITY ALOFT THAT
COULD AID IN SNOW AMOUNTS...ALTHOUGH SNOW RATIOS WILL BE ON THE LOW
SIDE UNTIL LATE IN THE DAY WHEN THE COLUMN COOLS FURTHER AS THE LOW
MOVES INTO SOUTHERN OHIO. AT THIS POINT...STRONG DYNAMICS INCLUDING
QVECTOR CONVERGENCE FROM 850-500 MILLIBARS ALONG WITH
FRONTOGENTICAL FORCING...DIFFLUENT FLOW ALOFT AND INSTABILITY
ALOFT SHOULD RESULT IN MODERATE TO HEAVY SNOW WITH BANDING PRODUCING
THE HIGHEST AMOUNTS.
SNOWFALL AMOUNTS WILL CONTINUE TO BE TRICKY...WITH THE GROUND AND
SURFACE TEMPERATURES STARTING OFF ABOVE FREEZING WHICH SHOULD LOWER
SNOW AMOUNTS FROM WHAT EARLIER MODEL RUNS HAD...UPWARDS OF 12 INCHES
IN THE HEAVIEST SNOW BAND. BUFKIT SUGGESTS THIS SCENARIO ALONG WITH
DECENT COMPACTION OF THE SNOW. ALSO...EXACT AREA OF PROLONGED
BANDING STILL UP IN THE AIR...HOWEVER A WIDESPREAD 6 INCH STORM
TOTAL SNOW AMOUNT LOOKS GOOD THROUGH MONDAY MORNING WITH 10 INCH
AMOUNTS AND LOCALLY HIGHER NEAR THE DEFORMATION ZONE WHICH SHOULD BE
FAIRLY CLOSE TO EITHER SIDE OF THE INTERSTATE 70 CORRIDOR AND A BIT
FURTHER NORTH OF THE LATE AFTERNOON HEAVY SNOW. WITH MODEL LOW
TRACKS AND RESULTANT SNOWFALL ACCUMULATION A LITTLE FURTHER
SOUTH...WILL UPGRADE THE SOUTHERNMOST TIER TO A WINTER STORM WARNING
AND KEEP THE WARNING GOING ELSEWHERE THROUGH NOON EDT MONDAY.
POPS WILL INCREASE TO OCCASIONAL FROM SOUTHWEST TO NORTHEAST TODAY
WITH MOST OR ALL OF CENTRAL INDIANA SEEING PRECIPITATION BY 18Z.
POPS WILL ONLY DROP SLIGHTLY TO LIKELY TOWARD MORNING.
COULD ALSO SEE SOME BLOWING SNOW TODAY AS BUFKIT SUGGESTS GUSTS TO
30 MPH OR MORE.
WITH THICK CLOUDS AROUND TODAY ALONG WITH EVAPORATIVE
COOLING...COLDER NAM MOS AND ALLBLEND TEMPERATURES IN THE
LOWER 30S NORTH TO THE MID 30S SOUTH LOOK GOOD.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 322 AM EDT SUN MAR 24 2013
MODELS AGREE THAT THROUGH THEIR QPF FIELDS THAT THE SNOW WILL BE
WINDING DOWN ON MONDAY WITH ONLY LINGERING SMALL SNOW SHOWER CHANCES
THROUGH TUESDAY. FINALLY...COULD SEE SOME CLEARING AND THE COLDEST
TEMPERATURES OF THE WEEK TUESDAY NIGHT WITH THE SNOW PACK SERVING TO
MAXIMIZE RADIATIONAL HEAT LOSS TO SPACE.
AFTERNOON TEMPERATURES WILL BE WELL BELOW NORMAL WITH THE
SNOW...NORTHWEST WINDS AND CLOUD COVER.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
ISSUED AT 355 AM EDT SUN MAR 24 2013
THE LONG TERM PERIOD WILL START OUT WITH HIGH PRESSURE AT THE
SURFACE AND RIDGING ALOFT. AS A RESULT...DRY CONDITIONS WILL
PREVAIL INTO FRIDAY. HOWEVER...LATEST REGIONAL INITIALIZATION
STILL WANTS TO BRING SLIGHT CHANCES FOR PRECIP INTO CENTRAL
INDIANA ON FRIDAY AND SATURDAY DUE TO A VERY SUBTLE WAVE IN THE
UPPER FLOW. AT THIS TIME...HAVE NOT SEEN ENOUGH CONSISTENCY IN
MODELS TO DIVERT FROM THAT FORECAST...SO WILL KEEP THE POPS WITH
LATEST INITIALIZATION. A SLIGHT WARMING TREND THROUGH THE EXTENDED
PERIOD WOULD KEEP ANY PRECIP THAT FALLS IN THE FORM OF RAIN.
&&
.AVIATION /DISCUSSION FOR THE 241500Z TAF UPDATE/...
ISSUED AT 1021 AM EDT SUN MAR 24 2013
INITIAL BURST OF SNOW HAS MADE IT THROUGH THE REGION AND IS NOW TO
THE EAST OF ALL TERMINALS AS OF 14Z. HAVE SEEN POCKETS OF MVFR WITH
POCKETS OF IFR CONDITIONS IN THE WAKE OF THE EARLY MORNING SNOW. ALL
EYES ARE QUICKLY TURNING TO ROUND 2 OF THE STORM...WITH HEAVY SNOW
MAKING ITS WAY EAST ACROSS MISSOURI AND INTO WESTERN ILLINOIS. RAPID
REFRESH HAS A NICE HANDLE ON THE PRECIP SHIELD BUT APPEARS TO BE
RUNNING A FEW HOURS SLOWER THAN WHAT IS CURRENTLY ONGOING.
HAVE MADE SOME ADJUSTMENTS AS A RESULT IN TIMING THE ONSET OF THE
PRECIP RETURN...LIKELY TO BEGIN IMPACTING ALL TERMINALS BETWEEN
17-20Z. MOST CURRENT LOW LEVEL THERMAL ANALYSIS IS NOW SUGGESTING
POTENTIAL FOR A PERIOD ON THE ORDER OF AN HOUR OR TWO WHERE SLEET
MAY MANAGE TO MIX WITH SNOW AT KIND...AND RAIN/SLEET MIXING WITH
SNOW AT KBMG AS THE AXIS OF WARMER AIR ALOFT PASSES THROUGH. AT KHUF
AND KLAF...EXPECT PRECIP AS ALL SNOW THIS AFTERNOON. AFTER
20-21Z...PRECIP SHOULD SWITCH BACK TO ALL SNOW AT KBMG AND KIND AS
COLDER AIR ADVECTS INTO THE REGION. SNOW IS LIKELY TO BECOME HEAVY
BY LATE AFTERNOON BASED ON OBS BACK TO OUR WEST. MAY ACTUALLY BE A
TOUCH CONSERVATIVE WITH RESPECT TO VISIBILITIES/CEILINGS AS
POTENTIAL WITHIN HEAVIER BANDS BY THIS EVENING FOR 1/4SM. WILL
ADDRESS IN GREATER DETAIL FOR THE 18Z FORECAST.
12Z DISCUSSION FOLLOWS.
SNOW WILL AFFECT TAF SITES IN 2 WAVES...BUT TRYING TO TIME THAT
BREAK IN THE SNOW IS POSING TO BE A CHALLENGE. SO FAR...THE TREND
HAS BEEN FOR CONDITIONS TO ABRUPTLY DROP TO IFR CATEGORY WITH THE
ONSET OF PRECIP. THERE WAS A BRIEF PERIOD OF RAIN/SNOW MIX AT KIND AT
INITIAL ONSET...BUT IT QUICKLY TRANSITIONED TO SNOW. EXPECT SNOW
FROM THIS POINT ON AT ALL TAF SITES. THE FIRST WAVE OF SNOW HAS
ALREADY ENDED AT KHUF...BUT SHOULD RESUME ONCE AGAIN BY LATE
MORNING. THE SAME TREND SHOULD OCCUR AT REMAINING TAF SITES WITHIN
THE NEXT HOUR OR 2 AND THEN RESUME AGAIN BY EARLY AFTERNOON AT
THOSE SITES AS WELL. SO...IMPROVED CONDITIONS TO MVFR CATEGORY DURING
THAT BRIEF WINDOW OF DRY CONDITIONS AT ALL TAF SITES...AND THEN
EXPECT THEM TO DETERIORATE QUICKLY TO IFR ONCE AGAIN WITH THE NEXT
WAVE OF SNOW. SNOW WILL IMPACT TAFS THROUGH THE REMAINDER OF TAF
PERIOD WITH IFR/LIFR BEING THE PREVAILING FLIGHT CATEGORY DURING
SECOND WAVE OF SNOW.
WINDS WILL STRENGTHEN WITHIN THE NEXT FEW HOURS OUT OF THE
NORTHEAST WITH SUSTAINED SPEEDS OF 12 TO 15 KTS AND GUSTS UP TO
28 KTS. WINDS WILL REMAIN STRONG THROUGH TONIGHT BUT BECOME
NORTHWESTERLY AFTER MIDNIGHT. DUE TO THE HEAVY/WET NATURE OF THE
SNOW...DO NOT EXPECT BLOWING SNOW TO BE AN IMPACT.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL NOON EDT MONDAY FOR INZ021-028>031-
035>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...MK
NEAR TERM...CP
SHORT TERM...MK
LONG TERM....TDUD
AVIATION...TDUD/RYAN
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
927 AM CDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 923 AM CDT SUN MAR 24 2013
A QUICK UPDATE SENT TO ADJUST PAST FALLEN SNOW TOTALS FROM
OVERNIGHT...WHICH NOW ARE CERTAIN TO HAVE BEEN 1 TO 3 INCHES FROM
EAST CENTRAL IOWA THROUGH WEST CENTRAL ILLINOIS. AFTER A MINOR
LULL IN SNOW EARLY THIS MORNING...WE ARE NOW SEEING A PUSH OF
RENEWED LIFT WHICH LOOKS TO AFFECT THE SOUTHERN 1/3 THIS MORNING.
THIS IS ALREADY CREATING HEAVY SNOW RATES IN OUR FAR SOUTH. SINCE
1/4 MILE HEAVY SNOW IS INTENSE ENOUGH NOT TO CARE ABOUT MARGINAL
TEMPERATURES VS LIGHT SNOW...OUR AMOUNT NEED TO BE RAISED. I AM
NOW GOING FOR DAYTIME ACCUMS OF 2 TO 4 INCHES IN THE SOUTH
1/3...WHICH WOULD TAKE EVENT TOTALS THROUGH 7 PM TONIGHT INTO THE
4 TO 7 RANGE. WHILE HIGH END ADVISORY AMOUNTS...THE REPORTED
AFFECTS IN THE SOUTH STILL SHOW WET ROADS...WITH SOME SLUSH...THUS
NO PLANS TO CHANGE HEADLINES ARE CONSIDERED AT THIS TIME.
FARTHER NORTH...MARGINAL TEMPS AND LIGHTER SNOWS SHOULD KEEP OUR
GOING FORECAST IN GOOD TRACK FOR NOW.
ERVIN
&&
.SYNOPSIS...
ISSUED AT 322 AM CDT SUN MAR 24 2013
06Z SFC ANALYSIS HAS THE LOW IN NORTHERN MISSISSIPPI WITH AN
INVERTED TROF INTO MISSOURI. ANOTHER TROF RAN FROM EASTERN MINNESOTA
INTO EASTERN IOWA. DEW POINTS WERE IN THE TEENS AND 20S OVER THE
GREAT LAKES AND MID MISSISSIPPI VALLEY WITH 30S AND HIGHER FROM THE
OHIO VALLEY ON SOUTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 322 AM CDT SUN MAR 24 2013
OVERALL AN INTERESTING SYSTEM. THE TRENDS OF BRINGING THE SYSTEM
NORTH HAVE ENDED UP BEING INCORRECT WITH THE MAIN LOW PASSING WELL
SOUTH OF THE AREA.
SATELLITE/RADAR SHOWS A BREAK IN THE SNOW ACROSS NORTHERN MISSOURI
BUT RAP TRENDS AND RECENT WATER VAPOR TRENDS INDICATE THIS BREAK IN
THE SNOW IS FILLING. THE WAA TOOL INDICATES THE BETTER SNOW WILL BE
ACROSS THE SOUTH IN THE HEADLINE AREA. HOWEVER...TEMPERATURES AT OR
JUST BELOW FREEZING IS ALLOWING SOME MELTING TO OCCUR WITH
ACCUMULATIONS BEING ON ELEVATED SURFACES. PAVEMENT TEMPERATURES ARE
AT OR ABOVE FREEZING SO MELTING IS OCCURRING THERE AS WELL.
SO...WILL CONTINUE WITH THE CURRENT HEADLINES AS IS. THE HWY 20
CORRIDOR HAS NOT YET SEEN ANY SNOW BUT THAT SHOULD CHANGE THIS
MORNING AS THE NEXT ROUND OF FORCING MOVES INTO THE AREA. INDIRECT
SOLAR INSOLATION WILL HELP PUSH TEMPERATURES ABOVE FREEZING DURING
THE DAY SO ADDITIONAL MELTING AND COMPACTION WILL OCCUR.
THE FURTHER SOUTH PASSAGE OF THE SYSTEM AND WARM TEMPERATURES WILL
HELP SUPPRESS OVERALL SNOWFALL AMOUNTS. IN THE ADVISORY AREA THE
EXTREME SOUTH PART OF THE CWFA SHOULD SEE 3-4 INCHES BY EVENING WITH
1-2 BY THE TIME ONE REACHES THE I-80 CORRIDOR. NORTH OF HWY 30
AMOUNTS SHOULD BE APPROACHING AN INCH.
TONIGHT...LIGHT SNOW WILL CONTINUE WITH IT ENDING ACROSS THE
NORTHERN THIRD OF THE CWFA AFTER MIDNIGHT. SOUTH OF A KOTM TO KGBG
LINE AMOUNTS AROUND OR JUST OVER AN INCH ARE EXPECTED WITH NOT QUITE
AN INCH AROUND THE I-80 CORRIDOR. NORTH OF HWY 30 A DUSTING TO ONE
HALF INCH IS EXPECTED. ..08..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 322 AM CDT SUN MAR 24 2013
LIGHT SNOW TO EXIT FAR SOUTHERN COUNTIES MON AM WITH PASSAGE
OF ELONGATED WEST-EAST UPPER TROUGH ON BACKSIDE OF OHIO VLY
SHORTWAVE. FEW FLURRIES MAY LINGER ACROSS ENTIRE AREA MON
WITH CYCLONIC FLOW AND COLD ADVECTION. 925 MB TEMPS AROUND
-5C SUPPORTS HIGHS MAINLY IN THE MIDDLE 30S. MON NGT... WITH
CONTINUED COLD ADVECTION AND CYCLONIC FLOW EXPECT PARTLY TO
MOSTLY CLOUDY SKIES AND THUS STAYED NEAR OR JUST ABOVE WARM
SIDE OF GUIDANCE ON LOWS. HOWEVER... AS CLOUDS GO SO GO THE
LOW TEMPS AND WILL NEED TO WATCH FOR POSSIBLY MORE CLEARING
AND COLDER LOWS WITH SOME SUGGESTION OF WEAK MID/UPPER LEVEL
RIDGING IN WAKE OF UPPER TROUGH.
TUE-TUE NGT... CYCLONIC FLOW TO KEEP AT LEAST PARTLY CLOUDY
SKIES TUE ESPECIALLY EASTERN 1/3-1/2... WITH ONLY SLIGHT
MODERATION ON TEMPS BY 1-3 DEGS FROM THOSE OF MON. CANT RULE
OUT FEW FLURRIES OR EVEN BRIEF SNOW SHOWER FAR EAST WITH
ENOUGH HEATING AS MODELS DEPICT WEAK ENERGY ROTATING DOWN
THROUGH WI AND NORTHERN IL TUE PM. PARTLY CLOUDY TO MOSTLY
CLEAR SKIES EXPECTED TUE NGT WITH SFC RIDGE AXIS BUILDING IN.
LOWS MAINLY UPPER TEENS TO LOWER 20S... BUT IF WINDS SHOULD
GO LIGHT FOR ANY LENGTH OF TIME THEN COULD SEE MINS AS COLD AS
AROUND 14-17 DEGS ESPECIALLY WEST/SOUTHWEST SECTIONS BEING IN
CLOSE PROXIMITY TO RIDGE AXIS.
WED-SAT... OVERALL MODERATING TEMPS LOOK TO BE IN STORE DURING
THE PERIOD... WITH TEMPS EDGING NEAR NORMAL TOWARD THE
END OF PERIOD AS THE PERSISTENT BLOCKING PATTERN OVER NORTH
AMERICA RESPONSIBLE FOR LOCKING IN THE COLD AIR IS SHOWN
TO BREAK DOWN. WITH THIS WARMING TREND WILL ALSO COME AT LEAST
SOME THREAT OF MAINLY LIGHT PRECIPITATION OVER THE LATTER HALF OF
THE WEEK BEING IN FAIRLY CLOSE PROXIMITY TO MID LEVEL BAROCLINIC
ZONE AND SUBJECT TO WEAK IMPULSES PROPAGATING DOWN IN NORTHWEST
FLOW ALOFT. CONSENSUS MODEL INTRODUCED SEVERAL PERIODS OF SLIGHT
CHC POPS FROM WED NGT THROUGH FRI... BUT GIVEN THE WEAK AND
VARYING SIGNAL FROM THE MODELS IT WAS COLLABORATED WITH
SURROUNDING OFFICES TO LOWER PRECIPITATION CHANCES BELOW MENTION
THROUGH FRI AND AWAIT FOR SOME BETTER CONSISTENCY. THE SIGNAL IS
STRONGER AND MORE CONSISTENT BY NEXT WEEKEND AND HAVE THEREFORE
LEFT IN PRECIPITATION CHCS BY SAT NGT. BEYOND THE SCOPE OF THE
EXTENDED... THE PATTERN REMAINS QUITE ACTIVE WITH THE MEDIUM RANGE
MODELS POINTING TO ANOTHER STORM SYSTEM POSSIBLY IMPACTING THE
AREA TOWARD THE MIDDLE PORTION OF THE FIRST WEEK OF APRIL WITH THE
POTENTIAL FOR AT LEAST MODERATE PRECIPITATION AMOUNTS WITH MAINLY
RAIN AND POSSIBLY SOME SNOW SUGGESTED. 05
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 632 AM CDT SUN MAR 24 2013
IFR/MVFR CONDITIONS WILL CONTINUE THROUGH 00Z/25 WITH LIFR
CONDITIONS MOST PROBABLE AT KBRL AS THE STORM SYSTEM MOVES INTO
THE OHIO VALLEY. AFT 00Z/25 IFR/MVFR CONDITIONS WILL SLOWLY
IMPROVE TO MVFR AS SNOW INTENSITIES GRADUALLY DECREASE. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR
IAZ087>089-098-099.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ025-
026-034-035.
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MOZ009-
010.
&&
$$
UPDATE...ERVIN
SHORT TERM...08
LONG TERM...05
AVIATION...08
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
636 AM CDT SUN MAR 24 2013
.SYNOPSIS...
ISSUED AT 322 AM CDT SUN MAR 24 2013
06Z SFC ANALYSIS HAS THE LOW IN NORTHERN MISSISSIPPI WITH AN
INVERTED TROF INTO MISSOURI. ANOTHER TROF RAN FROM EASTERN MINNESOTA
INTO EASTERN IOWA. DEW POINTS WERE IN THE TEENS AND 20S OVER THE
GREAT LAKES AND MID MISSISSIPPI VALLEY WITH 30S AND HIGHER FROM THE
OHIO VALLEY ON SOUTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 322 AM CDT SUN MAR 24 2013
OVERALL AN INTERESTING SYSTEM. THE TRENDS OF BRINGING THE SYSTEM
NORTH HAVE ENDED UP BEING INCORRECT WITH THE MAIN LOW PASSING WELL
SOUTH OF THE AREA.
SATELLITE/RADAR SHOWS A BREAK IN THE SNOW ACROSS NORTHERN MISSOURI
BUT RAP TRENDS AND RECENT WATER VAPOR TRENDS INDICATE THIS BREAK IN
THE SNOW IS FILLING. THE WAA TOOL INDICATES THE BETTER SNOW WILL BE
ACROSS THE SOUTH IN THE HEADLINE AREA. HOWEVER...TEMPERATURES AT OR
JUST BELOW FREEZING IS ALLOWING SOME MELTING TO OCCUR WITH
ACCUMULATIONS BEING ON ELEVATED SURFACES. PAVEMENT TEMPERATURES ARE
AT OR ABOVE FREEZING SO MELTING IS OCCURRING THERE AS WELL.
SO...WILL CONTINUE WITH THE CURRENT HEADLINES AS IS. THE HWY 20
CORRIDOR HAS NOT YET SEEN ANY SNOW BUT THAT SHOULD CHANGE THIS
MORNING AS THE NEXT ROUND OF FORCING MOVES INTO THE AREA. INDIRECT
SOLAR INSOLATION WILL HELP PUSH TEMPERATURES ABOVE FREEZING DURING
THE DAY SO ADDITIONAL MELTING AND COMPACTION WILL OCCUR.
THE FURTHER SOUTH PASSAGE OF THE SYSTEM AND WARM TEMPERATURES WILL
HELP SUPPRESS OVERALL SNOWFALL AMOUNTS. IN THE ADVISORY AREA THE
EXTREME SOUTH PART OF THE CWFA SHOULD SEE 3-4 INCHES BY EVENING WITH
1-2 BY THE TIME ONE REACHES THE I-80 CORRIDOR. NORTH OF HWY 30
AMOUNTS SHOULD BE APPROACHING AN INCH.
TONIGHT...LIGHT SNOW WILL CONTINUE WITH IT ENDING ACROSS THE
NORTHERN THIRD OF THE CWFA AFTER MIDNIGHT. SOUTH OF A KOTM TO KGBG
LINE AMOUNTS AROUND OR JUST OVER AN INCH ARE EXPECTED WITH NOT QUITE
AN INCH AROUND THE I-80 CORRIDOR. NORTH OF HWY 30 A DUSTING TO ONE
HALF INCH IS EXPECTED. ..08..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 322 AM CDT SUN MAR 24 2013
LIGHT SNOW TO EXIT FAR SOUTHERN COUNTIES MON AM WITH PASSAGE
OF ELONGATED WEST-EAST UPPER TROUGH ON BACKSIDE OF OHIO VLY
SHORTWAVE. FEW FLURRIES MAY LINGER ACROSS ENTIRE AREA MON
WITH CYCLONIC FLOW AND COLD ADVECTION. 925 MB TEMPS AROUND
-5C SUPPORTS HIGHS MAINLY IN THE MIDDLE 30S. MON NGT... WITH
CONTINUED COLD ADVECTION AND CYCLONIC FLOW EXPECT PARTLY TO
MOSTLY CLOUDY SKIES AND THUS STAYED NEAR OR JUST ABOVE WARM
SIDE OF GUIDANCE ON LOWS. HOWEVER... AS CLOUDS GO SO GO THE
LOW TEMPS AND WILL NEED TO WATCH FOR POSSIBLY MORE CLEARING
AND COLDER LOWS WITH SOME SUGGESTION OF WEAK MID/UPPER LEVEL
RIDGING IN WAKE OF UPPER TROUGH.
TUE-TUE NGT... CYCLONIC FLOW TO KEEP AT LEAST PARTLY CLOUDY
SKIES TUE ESPECIALLY EASTERN 1/3-1/2... WITH ONLY SLIGHT
MODERATION ON TEMPS BY 1-3 DEGS FROM THOSE OF MON. CANT RULE
OUT FEW FLURRIES OR EVEN BRIEF SNOW SHOWER FAR EAST WITH
ENOUGH HEATING AS MODELS DEPICT WEAK ENERGY ROTATING DOWN
THROUGH WI AND NORTHERN IL TUE PM. PARTLY CLOUDY TO MOSTLY
CLEAR SKIES EXPECTED TUE NGT WITH SFC RIDGE AXIS BUILDING IN.
LOWS MAINLY UPPER TEENS TO LOWER 20S... BUT IF WINDS SHOULD
GO LIGHT FOR ANY LENGTH OF TIME THEN COULD SEE MINS AS COLD AS
AROUND 14-17 DEGS ESPECIALLY WEST/SOUTHWEST SECTIONS BEING IN
CLOSE PROXIMITY TO RIDGE AXIS.
WED-SAT... OVERALL MODERATING TEMPS LOOK TO BE IN STORE DURING
THE PERIOD... WITH TEMPS EDGING NEAR NORMAL TOWARD THE
END OF PERIOD AS THE PERSISTENT BLOCKING PATTERN OVER NORTH
AMERICA RESPONSIBLE FOR LOCKING IN THE COLD AIR IS SHOWN
TO BREAK DOWN. WITH THIS WARMING TREND WILL ALSO COME AT LEAST
SOME THREAT OF MAINLY LIGHT PRECIPITATION OVER THE LATTER HALF OF
THE WEEK BEING IN FAIRLY CLOSE PROXIMITY TO MID LEVEL BAROCLINIC
ZONE AND SUBJECT TO WEAK IMPULSES PROPAGATING DOWN IN NORTHWEST
FLOW ALOFT. CONSENSUS MODEL INTRODUCED SEVERAL PERIODS OF SLIGHT
CHC POPS FROM WED NGT THROUGH FRI... BUT GIVEN THE WEAK AND
VARYING SIGNAL FROM THE MODELS IT WAS COLLABORATED WITH
SURROUNDING OFFICES TO LOWER PRECIPITATION CHANCES BELOW MENTION
THROUGH FRI AND AWAIT FOR SOME BETTER CONSISTENCY. THE SIGNAL IS
STRONGER AND MORE CONSISTENT BY NEXT WEEKEND AND HAVE THEREFORE
LEFT IN PRECIPITATION CHCS BY SAT NGT. BEYOND THE SCOPE OF THE
EXTENDED... THE PATTERN REMAINS QUITE ACTIVE WITH THE MEDIUM RANGE
MODELS POINTING TO ANOTHER STORM SYSTEM POSSIBLY IMPACTING THE
AREA TOWARD THE MIDDLE PORTION OF THE FIRST WEEK OF APRIL WITH THE
POTENTIAL FOR AT LEAST MODERATE PRECIPITATION AMOUNTS WITH MAINLY
RAIN AND POSSIBLY SOME SNOW SUGGESTED. 05
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 632 AM CDT SUN MAR 24 2013
IFR/MVFR CONDITIONS WILL CONTINUE THROUGH 00Z/25 WITH LIFR
CONDITIONS MOST PROBABLE AT KBRL AS THE STORM SYSTEM MOVES INTO
THE OHIO VALLEY. AFT 00Z/25 IFR/MVFR CONDITIONS WILL SLOWLY
IMPROVE TO MVFR AS SNOW INTENSITIES GRADUALLY DECREASE. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR
IAZ087>089-098-099.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ025-
026-034-035.
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MOZ009-
010.
&&
$$
SHORT TERM...08
LONG TERM...05
AVIATION...08
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
744 AM EDT SUN MAR 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 502 AM EDT SUN MAR 24 2013
WV IMAGERY AND RUC ANALYSIS INDICATED PERSISTENT HIGH LATITUDE
MID/UPPER LEVEL RIDGING FROM SCANDINAVIA INTO NORTHERN CANADA
RESULTING IN LOWER HEIGHTS AND COLDER AIR TO THE SOUTH ACROSS SRN
CANADA AND THE NRN CONUS. A WEAK RIDGE EXTENDED ACROSS THE WRN
GREAT LAKES BTWN MID LEVEL LOWS OVER THE DAKOTAS AND CANADIAN
MARATIMES. AT THE SFC...WEAK NE FLOW PREVAILED BETWEEN HIGH PRES
OVER SASK INTO NRN MANITOBA AND LOW PRES OVER THE LOWER MS VALLEY.
IR SATELLITE LOOP SHOWED AN EXTENSIVE AREA OF CLOUDS ACROSS THE
REGION WITH A RELATIVELY SMALL CLEAR AREA NE OF LAKE SUPERIOR.
WITH GENERALLY WEAK ONSHORE WINDS INTO NRN UPPER MI
OVERNIGHT...RADAR INDICATED NO PCPN. HOWEVER...AS WINDS INCREASE OUT
OF THE NORTHEAST AND 850 MB TEMPS REMAIN NER -11C...EXPECT SOME
LIGHT SNOW MAY STILL DEVELOP OVER THE WEST AND N CNTRL LOCATIONS
WHERE UPSLOPE FLOW PREVAILS. SINCE TEMPS IN THE MOIST LAYER REMAINED
BORDERLINE TO SUPPORT ICE CRYSTALS...A MIX OF -SN/FLURRIES/-FZDZ MAY
BE POSSIBLE. MODELS SUGGEST THAT THE DRY AIR TO THE NORTHEAST WILL
SPREAD ACROSS LAKE SUPERIOR INTO UPPER MI THIS AFTERNOON. THIS
SHOULD BRING AN END TO ANY PCPN THAT DEVELOPS EARLY TODAY. SOME
CLEARING MAY ALSO SPREAD FROM EAST INTO CNTRL UPPER MI BY LATE THIS
AFTERNOON WHICH SHOULD HELP BOOST TEMPS INTO THE LOWER TO MID 30S.
THE MODELS WERE CONSISTENT IN BRINGING ANOTHER BATCH OF 925-700 MB
MOISTURE INTO THE AREA FROM THE NORTHEAST TONIGHT. THIS WILL BRING
INCREASING CHANCES FOR LIGHT LAKE EFFECT SNOW...ESPECIALLY AFT
06Z...TO AREAS FAVORED BY UPSLOPE NNE FLOW IN N CNTRL AND WRN UPPER
MI. SINCE DEEPER MOISTURE TO AROUND -12C IS LIKELY...-FZDZ CHANCES
WILL BE REDUCED. THE CLOUDS WILL ALSO KEEP TEMPS FROM FALLING OFF
TOO MUCH WITH MIN READINGS AGAIN ABOVE NORMAL....IN THE LOW TO MID
20S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 443 AM EDT SUN MAR 24 2013
OUR STEADY NORTHERLY FLOW OFF LAKE SUPERIOR WILL CONTINUE THROUGH
WEDNESDAY...WITH LIGHT PRECIPITATION POSSIBLE NEARLY EVERY DAY NEAR
LAKE SUPERIOR. LOOK FOR TEMPERATURES TO SLOWLY INCREASE EACH
DAY...WITH SOUTH CENTRAL AREAS NEARING 40 DEGREES FOR A HIGH ON
THURSDAY...AND REMAINING IN THE UPPER 30S AND LOW 40S TO WRAP UP THE
WORK WEEK AND START THE UPCOMING WEEKEND.
THE NEXT GOOD SURGE OF PRECIPITATION WILL BE MONDAY THROUGH TUESDAY
MORNING...AS THE MID ATLANTIC LOW ROTATES MOISTURE BACK TOWARD THE
UPPER GREAT LAKES REGION. STILL IT WILL BE SET UP AOB ABOUT
800MB...WITH THE DGZ HOVERING AT THE TOP OF THIS MOISTURE LAYER TO
AROUND 600MB. WHILE THE MOST PRISTINE SNOW CRYSTALS WILL NOT BE
EXPECTED...850MB TEMPS HOVERING BETWEEN -10 AND -12C. SNOW AMOUNTS
AROUND A HALF INCH EVERY 6 HOURS WILL BE POSSIBLE MONDAY THROUGH
TUESDAY MORNING...HIGHEST OVER THE ELEVATED TERRAIN OF MARQUETTE
COUNTY...AND ACROSS WESTERN GOGEBIC AND ONTONAGON COUNTIES.
THE 500MB TROUGH WILL LIKELY REMAIN ENTRENCHED ACROSS CENTRAL AND
EASTERN UPPER MICHIGAN THROUGH TUESDAY NIGHT INTO WEDNESDAY. AT THAT
POINT NW FLOW LOOKS TO TAKE OVER ALOFT...WITH A SERIES OF WEAKER
WAVES SLIDING NEAR THE UPPER GREAT LAKES. WHILE WE DO HAVE SLIGHT
CHANCE POPS MENTIONED FOR DAY 5/FRIDAY INTO DAY 6/SATURDAY...THE
CONFIDENCE IS VERY LOW. THE ECMWF KEEP LOW PRESSURE STUCK UP NEAR
JAMES BAY AND HUDSON BAY ON FRIDAY...WITH HIGH PRESSURE STRETCHING
FROM SOUTH CENTRAL CANADA THROUGH THE UPPER GREAT LAKES. A WEAK COLD
FRONT MAY CROSS THURSDAY NIGHT INTO FRIDAY. THE 00Z MODEL RUNS LOOK
LESS THAN IMPRESSIVE WITH THE CHANCE FOR MEASURABLE PRECIP THROUGH
THE END OF THE FORECAST PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 743 AM EDT SUN MAR 24 2013
MVFR CONDITIONS THIS MORNING WITH SOME OCNL FLURRIES OR FREEZING
DRIZZLE WHERE UPSLOPE NNE FLOW PREVAILS AT CMX/SAW. CLOUDS AND ANY
PCPN IS EXPECTED TO END THIS AFTERNOON AS DRIER AIR
BUILDS INTO THE AREA AS STRONGER AND DEEPER NE FLOW SPREADS ACROSS
THE AREA. SITES MAY IMPROVE TO VFR BY LATE SUN AFTN OR SUN EVENING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 502 AM EDT SUN MAR 24 2013
HIGH PRESSURE OVER CENTRAL CANADA WILL KEEP A RIDGE OVER THE UPPER
GREAT LAKES REGION TODAY. BUT AS A LOW PRESSURE SYSTEM
DEPARTS THE CENTRAL PLAINS AND MOVES THROUGH THE OHIO RIVER VALLEY
THROUGH MONDAY NIGHT...THE RIDGE WILL WEAKEN AND SHIFT WEST. THIS
WILL LEAD TO PERSISTENT NORTHERLY FLOW ACROSS THE AREA...ALTHOUGH
THE WINDS SHOULD BE AT OR BELOW 25 KNOTS. AS THE LOW SHIFTS OFF
THE ATLANTIC SEABOARD ON TUESDAY...HIGH PRESSURE WILL BEGIN TO SHIFT
BACK TO THE EAST AND COVER THE UPPER GREAT LAKES FROM TUESDAY NIGHT
THROUGH THE REST OF THE WORK WEEK. THIS WILL KEEP THE NORTHERLY
WINDS BELOW 15KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1036 AM CDT SUN MAR 24 2013
...MAJOR WINTER STORM WITH HEAVY SNOW IMPACTING THE AREA...
.UPDATE...
ISSUED AT 1030 AM CDT SUN MAR 24 2013
FORECAST LOOKS TO BE ON TRACK WITH MAJOR WINTER STORM IMPACTING
THE AREA TODAY INTO THIS EVENING. SOME PARTS OF CENTRAL MISSOURI
ARE ALREADY REPORTING 7+ INCHES OF SNOW ON THE GROUND...WITH MANY
REPORTS OF HEAVY SNOW AND THUNDERSNOW ALL ALONG THE I-70 CORRIDOR
IN MISSOURI. THERE HAVE ALSO BEEN MORE REPORTS OF SLEET THAN
EARLIER ANTICIPATED IN THE WARM ADVECTION PRECIP STILL ONGOING
ACROSS PARTS OF SOUTHWEST/SOUTH CENTRAL ILLINOIS. HAVE UPDATED THE
FORECAST TO ADD IN SOME SLEET IN THESE AREAS...AND A SMALL PART OF
SOUTHEAST MISSOURI. OTHERWISE...LITTLE CHANGE TO THE GOING
FORECAST AT THIS TIME.
CARNEY
&&
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 336 AM CDT SUN MAR 24 2013
PRIMARY FCST ISSUE FOR TODAY IS THE ONGOING WINTER STORM. WAA PCPN
WHICH DVLPD ACROSS THE AREA LAST NIGHT BRIEFLY CHANGED OVER TO A
RAIN/SNOW MIX AND EVEN SWITCHED OVER TO PURE SNOW IN SOME
LOCATIONS BEFORE ENDING. THERE WILL BE A BRIEF BREAK EARLY THIS
MORNING BETWEEN THE DEPARTING WAA PCPN AND THE HEAVIER SNOW
ASSOCIATED WITH THE DEFORMATION ZONE WHICH HAS ALREADY DVLPD IN
ERN KS AND WRN MO. MODELS ARE IN GENERALLY GOOD AGREEMENT THIS
MORNING WITH THE TRACK OF THE LOW PRESSURE SYSTEM...ESPECIALLY THE
ECMWF WHICH HAS BEEN FAIRLY CONSISTENT WITH THE TRACK OF THE H85
LOW ALTHOUGH THE 24/00Z RUN IS SOMEWHAT SLOWER THAN THE 23/00Z RUN
BETWEEN 12Z AND 18Z. THE TRACK OF THE H85 CIRCULATION CENTER FROM
NEAR KSGF/KUMN TO NEAR KFAM/KMDH IS VERY FAVORABLE FOR HEAVY SNOW
ACROSS THE CENTRAL PART OF THE CWA BASED ON LOCAL CLIMATOLOGY
PLOTS.
THERE ARE TWO ASPECTS OF THIS EVENT THAT REALLY CAUGHT MY
ATTENTION. FIRST...BUFKIT CROSS SECTIONS FROM A COUPLE OF MODELS
/INCLUDING THE RAP AND SREF/ SHOW VERY STRONG LIFT FOCUSED THROUGH
A RESPECTABLY DEEP DENDRITIC GROWTH ZONE WHICH IS OCCASIONALLY
SUPERSATURATED WITH RESPECT TO ICE. THIS IS ESPECIALLY TRUE
BETWEEN 15Z AND 00Z. SECOND...NO MATTER HOW YOU SLICE THE
ATMOSPHERE...THERE ARE INDICATIONS OF MODEST INSTABILITY /AT LEAST
FOR A WINTER EVENT/ ACROSS PARTS OF MO/IL TODAY. FCSTS OF H7-H5
LAPSE RATES EXCEED 7 DEG C/KM ACROSS THE SRN HALF OF THE CWA ON
THE RAP/WRF/SREF/NAM/GFS/UKMET AND EVEN THE ECMWF FCST EXCEEDS 6.5
DEG C/KM. BUFKIT SOUNDINGS ALSO SHOW UP TO 50 J/KG OF ELEVATED
CAPE AT TIMES. TAKEN TOGETHER...THESE TWO ITEMS SUGGEST THAT THERE
WILL BE PERIODS OF EFFICIENT SNOWFALL PRODUCTION WITHIN THE
DEFORMATION ZONE ALONG WITH OCCASIONAL CONVECTIVE ELEMENTS WHICH
WILL LOCALLY ENHANCE SNOWFALL RATES. IN TERMS OF SNOWFALL
AMOUNTS...IT STILL LOOKS LIKE A SOLID 6-8 INCHES OF SNOW ACROSS
THE WINTER STORM WARNING AREA WITH HIGHER AMOUNTS POSSIBLE.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 24 2013
(TONIGHT - MONDAY NIGHT)
MODELS HAVE ALL COME INTO A HARMONIOUS CONFLUENCE OF SOLUTIONS WITH
THE 00Z RUNS...WITH THE AGREED UPON TRACK MOST SIMILAR TO THE ECMWF
24HRS AGO...WITH THE GFS/NAM MORE SLY...AND THE GEM MORE NLY...AND
PLACES THIS STORM IN ABOUT THE MOST PERFECT SPOT TO MAXIMIZE SNOW
TOTALS ACROSS THE I-70 CORRIDOR WITH AN ELONGATED H850 LO TRACKING
THRU SRN MO AND SRN IL. ANOTHER TREND...THIS ONE TEMPORAL...HAS
BEEN TO SLOW DOWN THE EWD TRANSLATION OF THE STORM BY ABOUT 6HRS...
MEANING THE DEF ZONE PCPN FROM IT WILL LINGER WELL INTO THIS EVENING
FOR THE IL COUNTIES AND AREAS JUST W OF THE MS RIVER AND PERHAPS
EARLY OVERNIGHT FOR PARTS OF SWRN-SRN IL. SNOWFALL TOTALS HAVE BEEN
BUMPED UP AS A RESULT OF THE SLOWER EXIT...WITH AN ADDITIONAL 2-3"
FOR MUCH OF THE IL COUNTIES AND AROUND AN INCH MORE FOR THE REST.
HAVE EXPANDED THE REACH OF THE WARNING BACK TO THE W A BIT MORE. BY
THE TIME IT IS ALL SAID AND DONE...THE PALM SUNDAY SNOWSTORM OF 2013
IS EXPECTED TO BE ONE OF THOSE ONCE-IN-A-GENERATION TYPE STORMS FOR
OCCURRING SO LATE IN THE YEAR AND BEING SO POTENT.
THIS POTENT STORM SYSTEM WILL BE EXITING JUST AS ANOTHER...WEAKER...
SYSTEM MOVES IN. THIS SYSTEM IS THE OLD MONTANA LO THAT IS EXPECTED
TO OPEN UP LATER TODAY AND GET SUCKED IN THE UNDERTOW OF TODAY AND
THIS EVENING/S STORM SYSTEM...BECOMING SHEARED BY THE TIME IT
REACHES OUR AREA LATER TONIGHT AND CONTINUING INTO MONDAY...BUT WITH
ENOUGH TO KEEP EITHER THE LIGHT SNOW OR SNOW SHOWERS GOING THRU LATE
MONDAY. SNOW ACCUMS LOOK TO BE AROUND AN ADDITIONAL INCH FOR MOST
AREAS...BUT OVER THE COURSE OF ANOTHER 12HRS OR SO. DEPENDING ON
HOW THIS ALL WORKS OUT...THE NATURE OF SHSN MAY SEE LOCALIZED HIGHER
AMOUNTS POSSIBLE. THE PERSISTENT LO CLOUDS SHOULD HANG IN TOUGH
THRU MONDAY AND WITH NW LO LEVEL WINDS AND LOTS OF FRESH SNOW
PACK...WHAT INSOLATION DOES MAKE IT THRU WILL GET MOSTLY BOUNCED
BACK...AND SO LOOK FOR MINIMAL TEMP RISES THIS DAY AS WELL...AND MOS
SEEMS TO HIGH ONCE AGAIN. UNDERCUT THE COLDER MET MOS NUMBERS BY A
COUPLE DEGS.
PERSISTENT CYCLONIC FLOW AND CLOUDS CONTINUE INTO MONDAY NIGHT AND
HAVE KEPT MENTION OF FLURRIES.
(TUESDAY - SATURDAY)
NW UPPER LEVEL FLOW WILL THEN CONTINUE FOR THE REMAINDER OF THE WEEK
CONTINUING THE BELOW AVERAGE TEMP REGIME AND ROUNDING OUT OUR RATHER
COLD MARCH. AN INVERTED TROF FOR THURSDAY AND THEN A CDFNT FOR
FRIDAY LOOK TO GIVE US SOME PCPN CHCS BY LATE IN THE WEEK...BUT
UNLIKE THE START OF THE WEEK...THESE PCPN CHCS SHOULD BE IN THE FORM
OF LIQUID.
TES
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 834 AM CDT SUN MAR 24 2013
SNOW...HEAVY AT TIMES...WILL CONTINUE AS THE DEFORMATION ZONE
PIVOTS OVER THE REGION TODAY AND TONIGHT. IFR CONDITIONS EXPECTED
THROUGH THE PERIOD.
UPDATE...SEVERAL LIGHTNING STRIKES NOTED IN THE INITIAL BAND HAS
RESULTED IN REPORTS OF THUNDERSNOW AND SNOWFALL RATES APPROACHING
3 INCHES PER HOUR. HAVE UPDATED TAFS TO INCLUDE THESE CONDITIONS
AT KCOU...AND METRO STL TERMINALS.
SPECIFICS FOR KSTL...
EXPECT VERY HEAVY SNOWFALL TODAY WITH CONDITIONS DROPPING AT OR
BELOW AIRPORT MINIMUMS. CONDITIONS TO SLOWLY IMPROVE...BUT REMAIN
IFR THIS EVENING AS DEFORMATION BAND OF SNOW PIVOTS AND SLOWLY
MOVES EAST.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CRAWFORD
MO-IRON MO-MADISON MO-REYNOLDS MO-ST. FRANCOIS MO-STE.
GENEVIEVE MO-WASHINGTON MO.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR JEFFERSON MO-
LINCOLN MO-PIKE MO-ST. CHARLES MO-ST. LOUIS CITY MO-ST.
LOUIS MO.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR AUDRAIN MO-
BOONE MO-CALLAWAY MO-COLE MO-FRANKLIN MO-GASCONADE MO-KNOX
MO-LEWIS MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-
OSAGE MO-RALLS MO-SHELBY MO-WARREN MO.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR RANDOLPH
IL.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR ADAMS IL-
BOND IL-BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-
JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
843 AM CDT SUN MAR 24 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 336 AM CDT SUN MAR 24 2013
PRIMARY FCST ISSUE FOR TODAY IS THE ONGOING WINTER STORM. WAA PCPN
WHICH DVLPD ACROSS THE AREA LAST NIGHT BRIEFLY CHANGED OVER TO A
RAIN/SNOW MIX AND EVEN SWITCHED OVER TO PURE SNOW IN SOME
LOCATIONS BEFORE ENDING. THERE WILL BE A BRIEF BREAK EARLY THIS
MORNING BETWEEN THE DEPARTING WAA PCPN AND THE HEAVIER SNOW
ASSOCIATED WITH THE DEFORMATION ZONE WHICH HAS ALREADY DVLPD IN
ERN KS AND WRN MO. MODELS ARE IN GENERALLY GOOD AGREEMENT THIS
MORNING WITH THE TRACK OF THE LOW PRESSURE SYSTEM...ESPECIALLY THE
ECMWF WHICH HAS BEEN FAIRLY CONSISTENT WITH THE TRACK OF THE H85
LOW ALTHOUGH THE 24/00Z RUN IS SOMEWHAT SLOWER THAN THE 23/00Z RUN
BETWEEN 12Z AND 18Z. THE TRACK OF THE H85 CIRCULATION CENTER FROM
NEAR KSGF/KUMN TO NEAR KFAM/KMDH IS VERY FAVORABLE FOR HEAVY SNOW
ACROSS THE CENTRAL PART OF THE CWA BASED ON LOCAL CLIMATOLOGY
PLOTS.
THERE ARE TWO ASPECTS OF THIS EVENT THAT REALLY CAUGHT MY
ATTENTION. FIRST...BUFKIT CROSS SECTIONS FROM A COUPLE OF MODELS
/INCLUDING THE RAP AND SREF/ SHOW VERY STRONG LIFT FOCUSED THROUGH
A RESPECTABLY DEEP DENDRITIC GROWTH ZONE WHICH IS OCCASIONALLY
SUPERSATURATED WITH RESPECT TO ICE. THIS IS ESPECIALLY TRUE
BETWEEN 15Z AND 00Z. SECOND...NO MATTER HOW YOU SLICE THE
ATMOSPHERE...THERE ARE INDICATIONS OF MODEST INSTABILITY /AT LEAST
FOR A WINTER EVENT/ ACROSS PARTS OF MO/IL TODAY. FCSTS OF H7-H5
LAPSE RATES EXCEED 7 DEG C/KM ACROSS THE SRN HALF OF THE CWA ON
THE RAP/WRF/SREF/NAM/GFS/UKMET AND EVEN THE ECMWF FCST EXCEEDS 6.5
DEG C/KM. BUFKIT SOUNDINGS ALSO SHOW UP TO 50 J/KG OF ELEVATED
CAPE AT TIMES. TAKEN TOGETHER...THESE TWO ITEMS SUGGEST THAT THERE
WILL BE PERIODS OF EFFICIENT SNOWFALL PRODUCTION WITHIN THE
DEFORMATION ZONE ALONG WITH OCCASIONAL CONVECTIVE ELEMENTS WHICH
WILL LOCALLY ENHANCE SNOWFALL RATES. IN TERMS OF SNOWFALL
AMOUNTS...IT STILL LOOKS LIKE A SOLID 6-8 INCHES OF SNOW ACROSS
THE WINTER STORM WARNING AREA WITH HIGHER AMOUNTS POSSIBLE.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 24 2013
(TONIGHT - MONDAY NIGHT)
MODELS HAVE ALL COME INTO A HARMONIOUS CONFLUENCE OF SOLUTIONS WITH
THE 00Z RUNS...WITH THE AGREED UPON TRACK MOST SIMILAR TO THE ECMWF
24HRS AGO...WITH THE GFS/NAM MORE SLY...AND THE GEM MORE NLY...AND
PLACES THIS STORM IN ABOUT THE MOST PERFECT SPOT TO MAXIMIZE SNOW
TOTALS ACROSS THE I-70 CORRIDOR WITH AN ELONGATED H850 LO TRACKING
THRU SRN MO AND SRN IL. ANOTHER TREND...THIS ONE TEMPORAL...HAS
BEEN TO SLOW DOWN THE EWD TRANSLATION OF THE STORM BY ABOUT 6HRS...
MEANING THE DEF ZONE PCPN FROM IT WILL LINGER WELL INTO THIS EVENING
FOR THE IL COUNTIES AND AREAS JUST W OF THE MS RIVER AND PERHAPS
EARLY OVERNIGHT FOR PARTS OF SWRN-SRN IL. SNOWFALL TOTALS HAVE BEEN
BUMPED UP AS A RESULT OF THE SLOWER EXIT...WITH AN ADDITIONAL 2-3"
FOR MUCH OF THE IL COUNTIES AND AROUND AN INCH MORE FOR THE REST.
HAVE EXPANDED THE REACH OF THE WARNING BACK TO THE W A BIT MORE. BY
THE TIME IT IS ALL SAID AND DONE...THE PALM SUNDAY SNOWSTORM OF 2013
IS EXPECTED TO BE ONE OF THOSE ONCE-IN-A-GENERATION TYPE STORMS FOR
OCCURRING SO LATE IN THE YEAR AND BEING SO POTENT.
THIS POTENT STORM SYSTEM WILL BE EXITING JUST AS ANOTHER...WEAKER...
SYSTEM MOVES IN. THIS SYSTEM IS THE OLD MONTANA LO THAT IS EXPECTED
TO OPEN UP LATER TODAY AND GET SUCKED IN THE UNDERTOW OF TODAY AND
THIS EVENING/S STORM SYSTEM...BECOMING SHEARED BY THE TIME IT
REACHES OUR AREA LATER TONIGHT AND CONTINUING INTO MONDAY...BUT WITH
ENOUGH TO KEEP EITHER THE LIGHT SNOW OR SNOW SHOWERS GOING THRU LATE
MONDAY. SNOW ACCUMS LOOK TO BE AROUND AN ADDITIONAL INCH FOR MOST
AREAS...BUT OVER THE COURSE OF ANOTHER 12HRS OR SO. DEPENDING ON
HOW THIS ALL WORKS OUT...THE NATURE OF SHSN MAY SEE LOCALIZED HIGHER
AMOUNTS POSSIBLE. THE PERSISTENT LO CLOUDS SHOULD HANG IN TOUGH
THRU MONDAY AND WITH NW LO LEVEL WINDS AND LOTS OF FRESH SNOW
PACK...WHAT INSOLATION DOES MAKE IT THRU WILL GET MOSTLY BOUNCED
BACK...AND SO LOOK FOR MINIMAL TEMP RISES THIS DAY AS WELL...AND MOS
SEEMS TO HIGH ONCE AGAIN. UNDERCUT THE COLDER MET MOS NUMBERS BY A
COUPLE DEGS.
PERSISTENT CYCLONIC FLOW AND CLOUDS CONTINUE INTO MONDAY NIGHT AND
HAVE KEPT MENTION OF FLURRIES.
(TUESDAY - SATURDAY)
NW UPPER LEVEL FLOW WILL THEN CONTINUE FOR THE REMAINDER OF THE WEEK
CONTINUING THE BELOW AVERAGE TEMP REGIME AND ROUNDING OUT OUR RATHER
COLD MARCH. AN INVERTED TROF FOR THURSDAY AND THEN A CDFNT FOR
FRIDAY LOOK TO GIVE US SOME PCPN CHCS BY LATE IN THE WEEK...BUT
UNLIKE THE START OF THE WEEK...THESE PCPN CHCS SHOULD BE IN THE FORM
OF LIQUID.
TES
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 834 AM CDT SUN MAR 24 2013
SNOW...HEAVY AT TIMES...WILL CONTINUE AS THE DEFORMATION ZONE
PIVOTS OVER THE REGION TODAY AND TONIGHT. IFR CONDITIONS EXPECTED
THROUGH THE PERIOD.
UPDATE...SEVERAL LIGHTNING STRIKES NOTED IN THE INITIAL BAND HAS
RESULTED IN REPORTS OF THUNDERSNOW AND SNOWFALL RATES APPROACHING
3 INCHES PER HOUR. HAVE UPDATED TAFS TO INCLUDE THESE CONDITIONS
AT KCOU...AND METRO STL TERMINALS.
SPECIFICS FOR KSTL...
EXPECT VERY HEAVY SNOWFALL TODAY WITH CONDITIONS DROPPING AT OR
BELOW AIRPORT MINIMUMS. CONDITIONS TO SLOWLY IMPROVE...BUT REMAIN
IFR THIS EVENING AS DEFORMATION BAND OF SNOW PIVOTS AND SLOWLY
MOVES EAST.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CRAWFORD
MO-IRON MO-MADISON MO-REYNOLDS MO-ST. FRANCOIS MO-STE.
GENEVIEVE MO-WASHINGTON MO.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR JEFFERSON MO-
LINCOLN MO-PIKE MO-ST. CHARLES MO-ST. LOUIS CITY MO-ST.
LOUIS MO.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR AUDRAIN MO-
BOONE MO-CALLAWAY MO-COLE MO-FRANKLIN MO-GASCONADE MO-KNOX
MO-LEWIS MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-
OSAGE MO-RALLS MO-SHELBY MO-WARREN MO.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR RANDOLPH
IL.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR ADAMS IL-
BOND IL-BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-
JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
646 AM CDT SUN MAR 24 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 336 AM CDT SUN MAR 24 2013
PRIMARY FCST ISSUE FOR TODAY IS THE ONGOING WINTER STORM. WAA PCPN
WHICH DVLPD ACROSS THE AREA LAST NIGHT BRIEFLY CHANGED OVER TO A
RAIN/SNOW MIX AND EVEN SWITCHED OVER TO PURE SNOW IN SOME
LOCATIONS BEFORE ENDING. THERE WILL BE A BRIEF BREAK EARLY THIS
MORNING BETWEEN THE DEPARTING WAA PCPN AND THE HEAVIER SNOW
ASSOCIATED WITH THE DEFORMATION ZONE WHICH HAS ALREADY DVLPD IN
ERN KS AND WRN MO. MODELS ARE IN GENERALLY GOOD AGREEMENT THIS
MORNING WITH THE TRACK OF THE LOW PRESSURE SYSTEM...ESPECIALLY THE
ECMWF WHICH HAS BEEN FAIRLY CONSISTENT WITH THE TRACK OF THE H85
LOW ALTHOUGH THE 24/00Z RUN IS SOMEWHAT SLOWER THAN THE 23/00Z RUN
BETWEEN 12Z AND 18Z. THE TRACK OF THE H85 CIRCULATION CENTER FROM
NEAR KSGF/KUMN TO NEAR KFAM/KMDH IS VERY FAVORABLE FOR HEAVY SNOW
ACROSS THE CENTRAL PART OF THE CWA BASED ON LOCAL CLIMATOLOGY
PLOTS.
THERE ARE TWO ASPECTS OF THIS EVENT THAT REALLY CAUGHT MY
ATTENTION. FIRST...BUFKIT CROSS SECTIONS FROM A COUPLE OF MODELS
/INCLUDING THE RAP AND SREF/ SHOW VERY STRONG LIFT FOCUSED THROUGH
A RESPECTABLY DEEP DENDRITIC GROWTH ZONE WHICH IS OCCASIONALLY
SUPERSATURATED WITH RESPECT TO ICE. THIS IS ESPECIALLY TRUE
BETWEEN 15Z AND 00Z. SECOND...NO MATTER HOW YOU SLICE THE
ATMOSPHERE...THERE ARE INDICATIONS OF MODEST INSTABILITY /AT LEAST
FOR A WINTER EVENT/ ACROSS PARTS OF MO/IL TODAY. FCSTS OF H7-H5
LAPSE RATES EXCEED 7 DEG C/KM ACROSS THE SRN HALF OF THE CWA ON
THE RAP/WRF/SREF/NAM/GFS/UKMET AND EVEN THE ECMWF FCST EXCEEDS 6.5
DEG C/KM. BUFKIT SOUNDINGS ALSO SHOW UP TO 50 J/KG OF ELEVATED
CAPE AT TIMES. TAKEN TOGETHER...THESE TWO ITEMS SUGGEST THAT THERE
WILL BE PERIODS OF EFFICIENT SNOWFALL PRODUCTION WITHIN THE
DEFORMATION ZONE ALONG WITH OCCASIONAL CONVECTIVE ELEMENTS WHICH
WILL LOCALLY ENHANCE SNOWFALL RATES. IN TERMS OF SNOWFALL
AMOUNTS...IT STILL LOOKS LIKE A SOLID 6-8 INCHES OF SNOW ACROSS
THE WINTER STORM WARNING AREA WITH HIGHER AMOUNTS POSSIBLE.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 24 2013
(TONIGHT - MONDAY NIGHT)
MODELS HAVE ALL COME INTO A HARMONIOUS CONFLUENCE OF SOLUTIONS WITH
THE 00Z RUNS...WITH THE AGREED UPON TRACK MOST SIMILAR TO THE ECMWF
24HRS AGO...WITH THE GFS/NAM MORE SLY...AND THE GEM MORE NLY...AND
PLACES THIS STORM IN ABOUT THE MOST PERFECT SPOT TO MAXIMIZE SNOW
TOTALS ACROSS THE I-70 CORRIDOR WITH AN ELONGATED H850 LO TRACKING
THRU SRN MO AND SRN IL. ANOTHER TREND...THIS ONE TEMPORAL...HAS
BEEN TO SLOW DOWN THE EWD TRANSLATION OF THE STORM BY ABOUT 6HRS...
MEANING THE DEF ZONE PCPN FROM IT WILL LINGER WELL INTO THIS EVENING
FOR THE IL COUNTIES AND AREAS JUST W OF THE MS RIVER AND PERHAPS
EARLY OVERNIGHT FOR PARTS OF SWRN-SRN IL. SNOWFALL TOTALS HAVE BEEN
BUMPED UP AS A RESULT OF THE SLOWER EXIT...WITH AN ADDITIONAL 2-3"
FOR MUCH OF THE IL COUNTIES AND AROUND AN INCH MORE FOR THE REST.
HAVE EXPANDED THE REACH OF THE WARNING BACK TO THE W A BIT MORE. BY
THE TIME IT IS ALL SAID AND DONE...THE PALM SUNDAY SNOWSTORM OF 2013
IS EXPECTED TO BE ONE OF THOSE ONCE-IN-A-GENERATION TYPE STORMS FOR
OCCURRING SO LATE IN THE YEAR AND BEING SO POTENT.
THIS POTENT STORM SYSTEM WILL BE EXITING JUST AS ANOTHER...WEAKER...
SYSTEM MOVES IN. THIS SYSTEM IS THE OLD MONTANA LO THAT IS EXPECTED
TO OPEN UP LATER TODAY AND GET SUCKED IN THE UNDERTOW OF TODAY AND
THIS EVENING/S STORM SYSTEM...BECOMING SHEARED BY THE TIME IT
REACHES OUR AREA LATER TONIGHT AND CONTINUING INTO MONDAY...BUT WITH
ENOUGH TO KEEP EITHER THE LIGHT SNOW OR SNOW SHOWERS GOING THRU LATE
MONDAY. SNOW ACCUMS LOOK TO BE AROUND AN ADDITIONAL INCH FOR MOST
AREAS...BUT OVER THE COURSE OF ANOTHER 12HRS OR SO. DEPENDING ON
HOW THIS ALL WORKS OUT...THE NATURE OF SHSN MAY SEE LOCALIZED HIGHER
AMOUNTS POSSIBLE. THE PERSISTENT LO CLOUDS SHOULD HANG IN TOUGH
THRU MONDAY AND WITH NW LO LEVEL WINDS AND LOTS OF FRESH SNOW
PACK...WHAT INSOLATION DOES MAKE IT THRU WILL GET MOSTLY BOUNCED
BACK...AND SO LOOK FOR MINIMAL TEMP RISES THIS DAY AS WELL...AND MOS
SEEMS TO HIGH ONCE AGAIN. UNDERCUT THE COLDER MET MOS NUMBERS BY A
COUPLE DEGS.
PERSISTENT CYCLONIC FLOW AND CLOUDS CONTINUE INTO MONDAY NIGHT AND
HAVE KEPT MENTION OF FLURRIES.
(TUESDAY - SATURDAY)
NW UPPER LEVEL FLOW WILL THEN CONTINUE FOR THE REMAINDER OF THE WEEK
CONTINUING THE BELOW AVERAGE TEMP REGIME AND ROUNDING OUT OUR RATHER
COLD MARCH. AN INVERTED TROF FOR THURSDAY AND THEN A CDFNT FOR
FRIDAY LOOK TO GIVE US SOME PCPN CHCS BY LATE IN THE WEEK...BUT
UNLIKE THE START OF THE WEEK...THESE PCPN CHCS SHOULD BE IN THE FORM
OF LIQUID.
TES
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 629 AM CDT SUN MAR 24 2013
A LATE SEASON WINTER STORM WILL BRING SEVERAL HOURS OF HEAVY SNOW
TO THE TERMINALS TODAY...PRIMARILY BETWEEN 15Z AND 21Z. VSBYS MAY
FALL BELOW ONE-QUARTER MILE AT TIMES. SNOW INTENSITY WILL DECREASE
TONIGHT HOWEVER SNOWFALL WILL CONTINUE TO ACCUMULATE. TOTAL
ACCUMULATIONS OF 6-10 INCHES ARE EXPECTED WITH LOCALLY HIGHER
AMOUNTS POSSIBLE. BUFKIT SOUNDINGS SHOW THAT IFR CIGS WILL
PROBABLY PERSIST THROUGH MOST OF THE TAF PD ALTHOUGH THERE MAY BE
BRIEF WINDOWS WHERE CIGS RISE TO MVFR. ISOLATED THUNDERSTORMS HAVE
ALSO BEEN OCCURRING ALONG AND SOUTH OF INTERSTATE 70. AIRPORT
STAFF SHOULD EXPECT RAPIDLY ACCUMULATING SNOWFALL IF AREAS OF
THUNDERSNOW MOVE DIRECTLY OVER A TAF SITE. SUSTAINED WIND SPEEDS
WILL APPROACH 20 KTS WITH GUSTS TO NEAR 30 KTS AT TIMES TODAY
BEFORE WIND SPEEDS DECREASE LATE TONIGHT.
SPECIFICS FOR KSTL...A PD OF HEAVY SNOW IS EXPECTED TO LAST FOR
SEVERAL HOURS AT KSTL TODAY. VSBYS MAY FALL BELOW ONE-QUARTER MILE
AT TIMES. SNOW INTENSITY WILL DECREASE TONIGHT HOWEVER SNOWFALL
WILL CONTINUE TO ACCUMULATE. TOTAL ACCUMULATIONS OF 6-10 INCHES
ARE EXPECTED WITH LOCALLY HIGHER AMOUNTS POSSIBLE. BUFKIT
SOUNDINGS SHOW THAT IFR CIGS WILL PROBABLY PERSIST THROUGH MOST OF
THE TAF PD ALTHOUGH THERE MAY BE BRIEF WINDOWS WHERE CIGS RISE TO
MVFR. ISOLATED THUNDERSTORMS HAVE ALSO BEEN OCCURRING WITH THIS
STORM SYSTEM...THEREFORE AIRPORT STAFF SHOULD EXPECT RAPIDLY
ACCUMULATING SNOWFALL IF AREAS OF THUNDERSNOW MOVE DIRECTLY OVER
KSTL. SUSTAINED WIND SPEEDS WILL APPROACH 20 KTS WITH GUSTS TO
NEAR 30 KTS AT TIMES TODAY BEFORE WIND SPEEDS DECREASE LATE
TONIGHT.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CRAWFORD
MO-IRON MO-MADISON MO-REYNOLDS MO-ST. FRANCOIS MO-STE.
GENEVIEVE MO-WASHINGTON MO.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR JEFFERSON MO-
LINCOLN MO-PIKE MO-ST. CHARLES MO-ST. LOUIS CITY MO-ST.
LOUIS MO.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR AUDRAIN MO-
BOONE MO-CALLAWAY MO-COLE MO-FRANKLIN MO-GASCONADE MO-KNOX
MO-LEWIS MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-
OSAGE MO-RALLS MO-SHELBY MO-WARREN MO.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR RANDOLPH
IL.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR ADAMS IL-
BOND IL-BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-
JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
932 AM CDT SUN MAR 24 2013
...A COLD AND SUNNY START WITH WIND CHILLS PUSHING ZERO AT MID-
MRNG THEN NW WINDS INCREASE AND BECOME GUSTY AFTER 11 AM...
.UPDATE...
ISSUED AT 932 CDT SUN MAR 24 2013
CYCLOGENESIS IS UNDERWAY OVER THE MID MS VALLEY. A SHRTWV RIDGE IS
OVER THE FCST AREA IN ITS WAKE AND HAS RESULTED IN CLEARING. 12Z
SOUNDINGS SHOW EXTENSIVE MSTR ALL THE WAY BACK TO MT/ND. SO EXPECT
DIURNAL STRATOCU TO DEVELOP AROUND MIDDAY.
THE BACK EDGE OF THE CIRRUS CANOPY WITH THE MID MS VALLEY LOW WAS
EXITING OUR ERN COUNTIES ALONG HWY 81. THESE AREAS WILL BECOME SUNNY
BY 11 AM.
VIS SATELLITE ALSO SHOW SOME MID-HIGH CLOUDS OVER WY AND NRN CO.
THESE CLOUDS WILL ALSO DIVE SE INTO THE FCST AREA. SO OVERALL EXPECT
A SUNNY MRNG TO TURN P/CLOUDY THIS AFTN.
DID MAKE SOME SUBSTANTIAL ADJUSTMENTS TO SKY FCST FORENOON TO ACCT
FOR CLEARING. WILL CONT TO MONITOR TEMP CURVES.
IT/S COLD! THE CAMBRIDGE CO-OP OBSERVER HAD A LOW TEMP OF 9F. AN
NDOR MESONET SITE IN ARAPAHOE ALSO REPORTED 9F. WIND CHILLS ARE
MOSTLY IN THE SINGLE DIGITS ACROSS THE FCST AREA.
OVERALL A BLUSTERY COLD DAY. 06Z NAM/11Z RAP BUFKIT TIME SECTIONS
SUGGEST PEAK WINDS AVAILABLE FOR MIXING ARE 30-33 KTS. SO NW WINDS
WILL GUST 25-35 MPH...THO LESS FREQUENTLY IN THE 30-35 MPH RANGE.
OTHER THAN SHORT-TERM SKY ALL OTHER FCST ELEMENTS LOOK GOOD.
ANALOGS: LOOKING BACK AT THE FCST ANALOG YEARS FROM 10 DAYS AGO...
THEY HAD A GREAT SIGNAL FOR THIS CURRENT STRETCH OF UNSEASONABLY
COLD MARCH WX. THOSE INCLUDED 1951 52 57 58 62 AND 2006.
UPDATE ISSUED AT 543 AM CDT SUN MAR 24 2013
UPDATED THE FORECAST FOR TODAY TO MAKE MINOR ADJUSTMENTS TO HOURLY
TEMPERATURES...WINDS...AND DEWPOINTS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 509 AM CDT SUN MAR 24 2013
THE MAIN CHALLENGE WILL BE DETERMINING CHANCES FOR FLURRIES/SNOW
SHOWERS TODAY AND TONIGHT.
UPPER LEVEL JET STREAM HAS MADE A DIVE WELL SOUTH OF THE AREA WITH A
RATHER LARGE LONGWAVE TROUGH OVER THE CENTRAL UNITED STATES. THIS
SHOULD ENSURE THAT WE REMAIN WELL BELOW NORMAL TODAY. AT
MID-LEVELS...A SOMEWHAT COMPLEX SCENARIO IS TAKING PLACE. A SET OF
DUMBBELL CLOSED LOWS OCCUPY THE AFOREMENTIONED LONGWAVE
TROUGH...WITH ONE OF THE LOWS TRACKING TO THE EAST ACROSS
SOUTHEASTERN KANSAS. THE SECOND LOW IS LOCATED OVER NORTH DAKOTA.
FOR TODAY...WE SHOULD BE IN AN AREA BETWEEN THE TWO CLOSED
LOW...WITH SOME SHORTWAVE RIDGING. THIS SHOULD KEEP FLURRIES/SNOW
SHOWERS OUT OF THE AREA DURING THE DAY TODAY...AND PERHAPS ALLOW A
PEAK OR TWO AT SOME SUN. WITH 850 MB TEMPERATURES RATHER SIMILAR TO
SATURDAY...AND WITH THE BIT OF CHANCE AT A PEAK OR TWO OF LATE MARCH
SUN...I HAVE BUMPED UP TEMPERATURES A BIT FOR TODAY.
THE APPROACHING CLOSED LOW IS EXPECTED TO FILL TODAY AS IT HEADS
SOUTH. THE LEFTOVER LOBE OF ENERGY WILL ARRIVE THIS EVENING AND
COULD SPAWN MORE FLURRIES/SNOW SHOWERS...WITH BETTER CHANCES TO THE
EAST/NORTHEAST...WITH THE BEST LARGE SCALE TO THE EAST/NORTHEAST. I
WENT WITH SIMILAR LOW TEMPERATURES TONIGHT COMPARED TO THE PREVIOUS
FORECAST WITH ONLY MINOR ADJUSTMENTS. BUMPED UP WIND SPEEDS JUST A
BIT WITH INCREASING LOW-LEVEL LAPSE RATES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 509 AM CDT SUN MAR 24 2013
THIS 6-DAY PERIOD WILL BE HIGHLIGHTED BY WHAT CURRENTLY APPEARS TO
BE A FEW LOW-END CHANCES FOR GENERALLY LIGHT MEASURABLE PRECIP...BUT
MORE IMPORTANTLY TO MANY FOLKS...A LEGITIMATE WARMING TREND BACK
INTO THE 40S AND AT LEAST 50S.
CERTAINLY MONDAY THROUGH TUESDAY THE AREA WILL STILL BE MIRED IN THE
MUCH-BELOW NORMAL COLD AIR. STARTING OFF SUNRISE MONDAY
MORNING...00Z/06Z MODELS SUCH AS THE NAM/GFS/ECMWF ARE IN GOOD
AGREEMENT DEPICTING AN ELONGATED MID LEVEL TROUGH EXTENDING FROM
NORTHWEST-SOUTHEAST ACROSS THE CENTRAL PLAINS...WHICH THEN GRADUALLY
DEPARTS TO THE SOUTHEAST DURING THE DAY...FEEDING INTO THE ENTRANCE
REGION OF A STOUT UPPER LEVEL JET STREAK ACROSS THE SOUTHEAST CONUS.
AT THE SURFACE MONDAY...ALTHOUGH A GRADUAL DECREASE IN WIND SPEEDS
WILL OCCUR DURING THE DAY...THE COMBINATION OF DEEP MIXING AND A
STILL TIGHTENED PRESSURE GRADIENT WILL RESULT IN FAIRLY BREEZY
CONDITIONS WITH SUSTAINED NORTHWEST WINDS AT LEAST 20 MPH GUSTING
25-30 MPH. THESE WINDS WILL RESULT IN ANOTHER VERY COLD DAY FOR LATE
MARCH...WITH WIND CHILL READINGS DURING THE AFTERNOON STRUGGLING TO
REACH THE LOW 20S. ACTUAL AIR TEMPERATURES WILL BE VERY SIMILAR TO
THOSE OF TODAY...WITH LOW TO POSSIBLY MID 30S CWA-WIDE.
PRECIPITATION-WISE...AS NOTED BY THE PAST SEVERAL FORECAST
SHIFTS...THIS IS A FAIRLY CLASSIC SETUP FOR AT LEAST A SLIGHT CHANCE
OF FLURRIES...AS FORCING FROM THE OVERHEAD ELONGATED SHORTWAVE
COMBINES WITH FAVORABLE DENDRITIC TEMPERATURES AROUND -11C IN A LOW
STRATUS LAYER TO SQUEEZE OUT SOME FLAKES. AS NOTED BY PREVIOUS DAY
SHIFT...PARTS OF THE EASTERN CWA COULD EVEN SEE SOME VERY LIGHT
MEASURABLE SNOW OF MAYBE A TENTH OF AN INCH OR TWO...AS SUGGESTED BY
LIGHT QPF EVIDENT IN VARIOUS MODEL FIELDS. AS A RESULT...MAINTAINED
A FLURRY CHANCE IN THE WEST THROUGH THE DAY...BUT ACTUALLY BEEFED UP
ROUGHLY THE NORTHEAST 1/2 OF THE CWA TO A 20 TO 30 PERCENT CHANCE OF
MEASURABLE LIGHT SNOW. THIS SHOULDN/T BE ANY KIND OF IMPACTFUL
SNOW...BUT FELT IT WAS WORTHY OF A SMALL POP AS SOME AREAS COULD SEE
A BIT MORE THAN FLURRIES. BY SUNSET MONDAY NIGHT...THE
AFOREMENTIONED MID LEVEL WAVE WILL BE JUST DEPARTING THE SOUTHERN
END OF THE CWA...AND ALTHOUGH SOME DEGREE OF LOW STRATUS COULD
LINGER THROUGH THE NIGHT...FEEL THE RISK OF LINGERING FLURRIES/LIGHT
SNOW IS LOW ENOUGH BY THEN TO END THE MENTION. TEMP-WISE...ITS VERY
POSSIBLE THAT MONDAY NIGHT COULD IN FACT BE THE COLDEST NIGHT FOR
THE NEXT SEVERAL MONTHS...AS A SURFACE RIDGE AXIS SETTLES IN AND
BREEZES BECOME VERY LIGHT BY SUNRISE. ALTHOUGH LINGERING CLOUDS
COULD WORK AGAINST A MAJOR DROP-OFF...WILL STILL CALL FOR MOST OF
THE CWA SETTLING DOWN TO AT LEAST 14-18 DEGREES. DESPITE THE LIGHT
WINDS...AM NOT OVERLY CONCERNED ABOUT IMPACTFUL FOG DEVELOPMENT...SO
WILL CONTINUE TO OMIT FROM THE FORECAST.
TUESDAY/TUESDAY NIGHT...CONFIDENCE IS RATHER HIGH IN A PRECIP-FREE
24 HOURS...ALTHOUGH WILL ACKNOWLEDGE THAT THE ECMWF CONTINUES TO
SPIT OUT SOME VERY LIGHT QPF NEAR THE SOUTHWEST EDGE OF THE CWA LATE
TUES NIGHT...LIKELY IN RESPONSE TO A MODEST BELT OF LOW-MID LEVEL
THETA-E ADVECTION AS A VERY SUBTLE MID LEVEL SHORTWAVE TROUGH
RIPPLES THROUGH WEST-NORTHWEST FLOW ALOFT. THE THINKING FOR NOW IS
THAT FAIRLY DRY LOW LEVELS WILL WORK AGAINST PRECIP
DEVELOPING...ESPECIALLY OF THE MEASURABLE VARIETY. HOWEVER...IT WILL
BEAR WATCHING AS TEMPERATURE PROFILES WOULD SUGGEST A LOW-END RISK
OF LIGHT FREEZING RAIN IF SOMETHING WERE TO MOVE IN. FOR NOW WILL
LEAVE TUES NIGHT PRECIP FREE THOUGH. BACKING UP TO THE TUESDAY
DAYTIME HOURS...DEVELOPING SOUTHERLY BREEZES SHOULD MARK THE
BEGINNING STAGES OF A NICE WARM-UP...AND NUDGED UP HIGH TEMPS A BIT
GETTING NEARLY ALL AREAS INTO THE LOW OR MID 40S.
WEDNESDAY/WEDNESDAY NIGHT...HAVE MAINTAINED A DRY
FORECAST...ALTHOUGH ITS NOT NECESSARILY A GUARANTEE TO STAY THAT WAY
AS BOTH THE ECMWF/GFS CONTINUE TO BRING A SERIES OF WEAK SHORTWAVES
THROUGH THE PERSISTENT WEST-NORTHWEST FLOW...WHICH COULD SATURATE
THE MID LEVELS JUST ENOUGH TO PRODUCE SOME SPRINKLES OR LIGHT RAIN.
AGAIN...CONFIDENCE JUST ISN/T HIGH ENOUGH TO GO THERE YET.
TEMP-WISE...THE WARM-UP CONTINUES WITH ALL NEBRASKA ZONES AIMED WELL
INTO THE MID-UPPER 40S AND EVEN SOME 50S NEAR/SOUTH OF THE STATE
LINE.
THURSDAY/THURSDAY NIGHT...BROAD WEST-NORTHWEST FLOW JUST KEEPS ON
PERSISTING OVER THE CENTRAL PLAINS...WITH EVEN A HINT OF HEIGHT
RISES AS A RIDGE BUILDS EASTWARD A BIT FROM THE ROCKIES. ALTHOUGH
ODDS ARE REASONABLY HIGH THAT THIS 24 HOURS WILL REMAIN
DRY...ESPECIALLY THE DAYTIME...WILL CONTINUE TO HANG ONTO A SLIGHT
CHANCE OF RAIN THURSDAY NIGHT FROM THE PREVIOUS FORECAST...ALTHOUGH
THIS CHANCE MAY VERY WELL BE DROPPED IN THE COMING DAYS. CONTINUED
MODIFICATION OF THE LOW LEVEL TEMPERATURE FIELDS RAISES CONFIDENCE
IN WIDESPREAD 50S FOR THURSDAY...WHICH WOULD MARK THE FIRST TIME IN
9-13 DAYS THAT MOST OF THE CWA HAS CRACKED 50.
FRIDAY/FRIDAY NIGHT...THE CWA-WIDE SLIGHT CHANCES OF RAIN SHOWERS
WERE MAINTAINED FROM THE PREVIOUS FORECAST...BUT AGAIN ITS BY NO
MEANS LOOKING LIKE A WIDESPREAD MEASURABLE RAIN RISK. THAT BEING
SAID...GRADUAL MOISTENING OF THE LOW LEVELS EVIDENT AT 850 MILLIBARS
COULD ACTUALLY GENERATE SOME WEAK INSTABILITY BY THIS TIME...AND
THUS ITS NOT COMPLETELY OUT OF THE QUESTION THAT A FEW WEAK
THUNDERSTORMS COULD MATERIALIZE ON A HIT AN MISS BASIS. WILL HOLD
OFF ON ANY THUNDER MENTION FOR NOW STILL BEING 5+ DAYS OUT...BUT
SOMETHING TO KEEP AN EYE ON. FOR NOW...WILL KEEP HIGH TEMPS FRIDAY
SIMILAR TO THURS WITH MID-UPPER 50S...BUT THE MEX GUIDANCE WOULD
SUGGEST IT COULD BE A BIT WARMER THAN THIS.
FINALLY FOR SATURDAY DAYTIME...CHANCES FOR RAIN SHOWERS CURRENTLY
APPEAR A BIT BETTER THAN PREVIOUS DAYS...AND THUS WILL GO WITH SOME
30 POPS BUT STILL KEEPING CHANCES FAIRLY LOW AT THIS TIME RANGE.
ESPECIALLY THE ECMWF SUGGESTS THAT A MODEST SHORTWAVE TROUGH COULD
DROP IN FROM THE NORTHWEST...AND PUSH A WEAK COLD FRONT THROUGH THE
REGION...PROVIDING A BIT MORE FORCING. AGAIN WILL HOLD OFF ON THE
INTRODUCTION OF THUNDERSTORMS AND JUST GO WITH SHOWER WORDING...BUT
THIS WILL BEAR WATCHING AS WEAK INSTABILITY COULD CERTAINLY BE IN
PLACE BY THEN. WILL AIM HIGH TEMPS IN THE 50S AGAIN...BUT DEPENDING
ON HOW TRENDS PLAY OUT WOULD NOT BE SURPRISED TO SEE SOME AREAS
CRACK 60.
&&
.AVIATION...(FOR THE 12Z TAF THROUGH 12Z MONDAY MORNING)
ISSUED AT 543 AM CDT SUN MAR 24 2013
CEILINGS SHOULD REMAIN VFR FOR THE FORECAST FOR THE MOST PART.
AN INCREASE OF LOW-LEVEL LAPSE RATES WILL INCREASE WIND SPEEDS AND GUSTS
FOR TODAY. COULD GET SOME FLURRIES TONIGHT...BUT CHANCES ARE LOW ENOUGH
NOT TO INCLUDE IN THE FORECAST FOR NOW...AND INCLUDED A LOW-LEVEL
SCATTERED LAYER...WHICH WOULD BECOME BROKEN IF FLURRIES DEVELOP.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...HEINLEIN
LONG TERM...PFANNKUCH
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1100 AM EDT SUN MAR 24 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER THE MISSISSIPPI RIVER VALLEY WILL MOVE
NORTHEAST INTO THE OHIO VALLEY TONIGHT. A SECOND AREA OF LOW
PRESSURE WILL DEVELOP NEAR CAPE FEAR THIS AFTERNOON AND MOVE SLOWLY
UP THE COAST TO NEAR NEW JERSEY BY MONDAY AFTERNOON. A COOL
NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1100 AM SUNDAY...
TODAY:
THE SURFACE LOW THAT DEVELOPED OVER THE SOUTHERN MISSISSIPPI RIVER
VALLEY OVERNIGHT WILL CONTINUE TO SPLIT INTO TWO SEPARATE LOWS AS IT
MOVES NORTH AND EAST THIS MORNING. THE WESTERN MOST LOW WILL DEEPEN
AS IT MOVES NORTHEAST ALONG THE WEST SIDE OF THE APPALACHIANS...
WHILE THE SECOND WILL INTENSIFY OFF THE SE ATLANTIC COAST AND
MIGRATE NE ALONG IT. ALTHOUGH SOME LIGHT TO MODERATE RAIN HAS MOVED
INTO CENTRAL NC THIS MORNING...THE STRONGEST CONVECTION AND HEAVIEST
RAINFALL HAS REMAINED SOUTH OF THE AREA. 12Z UPPER AIR ANALYSES SHOW
THE H85 LOW ALREADY SPLITTING...WITH SOME INDICATION OF THE
SECONDARY LOW AT 700 MB. CENTRAL NC IS UNDER THE RIGHT REAR QUADRANT
OF THE 150+ KT UPPER LEVEL JET...WITH A SECOND JET...WITH WINDS JUST
UNDER 150 KTS...TO THE SOUTHEAST. WHILE SURFACE WINDS ARE MAINLY ENE
TO NE ACROSS THE AREA...UPPER LEVEL WINDS ARE SOUTH AND SW. AS THE
LOW MOVES OFF THE ATLANTIC COAST UPPER LEVEL WINDS SHOULD BRIEFLY
BACK AROUND TO MORE SOUTHEASTERLY BEFORE THE LOW...INITIALLY TO THE
WEST OF THE APPALACHIANS...MOVES EAST THROUGH THE MID ATLANTIC. THE
10Z HRRR AND THE 00Z HIRES WRF-ARW CONVECTION ALLOWING MODELS...
WHICH ARE CAPTURING THE CURRENT REFLECTIVITIES BEST...INDICATE AN
AREA OF LIGHT RAINFALL FILLING IN BEHIND THE BREAK...MAINLY ACROSS
THE NORTH AND NORTHWEST WITH SOME SHOWERS POSSIBLE THROUGH TONIGHT.
AS SUCH...CONTINUE WITH 100 PERCENT CHANCE FOR RAIN INTO THE
AFTERNOON WITH CHANCES GRADUALLY DECREASING ACROSS THE WEST AND
SOUTH THIS AFT/EVE. WHILE RAINFALL AMOUNTS ARE NOT ENTIRELY
CERTAIN...HPC GUIDANCE APPEARS TO BE A BIT OVERDONE. GIVEN THE DRY
SLOT MOVING INTO THE WEST AND THE FORECAST REFLECTIVITIES FROM THE
CONVECTION ALLOWING MODELS...WILL HAVE RAINFALL AMOUNTS LESS THAN
GUIDANCE...WITH HIGHEST TOTALS ACROSS THE NORTH. -KC
WITH THE HYBRID COLD AIR DAMMING EVENT TODAY AND TONIGHT...
TEMPERATURES WILL FEATURE VERY LITTLE DIURNAL RANGE...ESPECIALLY IN
THE HEART OF THE DAMMING REGION. HIGHS SHOULD RANGE IN THE UPPER 30S
IN THE NW PIEDMONT TO THE MID 40S IN THE SOUTHERN COASTAL PLAIN.
TEMPERATURES TONIGHT WILL FEATURE ONLY A MODEST DROP OFF WITH LOWS
TONIGHT WILL RANGING FROM THE LOWER/MID 30S ACROSS THE NORTHWEST TO
UPPER 30S SOUTHEAST. -BLAES
TONIGHT:
THE LAST BATCH OF SHOWERS...POSSIBLY INCLUDING SOME SHALLOW
CONVECTION WILL SWING EAST AND NORTHEAST THROUGH CENTRAL NC BETWEEN
02-08Z. WITH ANY LINGERING PRECIPITATION HUGGING THE VA BORDER OR
PERHAPS SOME PATCHY DRIZZLE. THERE IS SOME CONCERN THAT THE BOUNDARY
LAYER MAY COOL ENOUGH TO REACH FREEZING ON MONDAY MORNING IN THE
TRIAD AREA WHICH COULD RESULT IN SOME BLACK ICE. WHILE THE NEAR
SURFACE FLOW IS BECOMING SOUTHWEST/WEST AND DRYING...IT APPEARS THAT
SKIES SHOULD REMAIN CLOUDY THROUGH DAYBREAK LIMITING RADIATIONAL
COOLING. SUBSEQUENT SHIFTS WILL NEED TO MONITOR THE POTENTIAL FOR
SOME CLEARING AND A SUDDEN DROP IN SURFACE TEMPS AT DAYBREAK
ALTHOUGH THIS APPEARS UNLIKELY AS TURBULENT MIXING WILL LIKELY BE
ONGOING AND LIMIT SFC COOLING. -BLAES
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 315 AM SUNDAY...
MONDAY AND MONDAY NIGHT:
THE INLAND SFC LOW(OVER THE TN/OH VALLEY)ASSOCIATED WITH THE MILLER
B STORM SYSTEM WILL QUICKLY GIVE WAY TO THE RAPIDLY INTENSIFYING
SECONDARY LOW LIFTING NORTHWARD UP THE MID ATLC COAST MONDAY
MORNING. AS THE SYSTEM GAINS NORTHERN LATITUDE...THE RESULTANT
WEST-NWLY LOW-LEVEL FLOW WILL ADVECT COLDER-DRIER AIR INTO THE
AREA...SCOURING OUT THE RESIDUAL DAMMING AIRMASS LEADING TO PARTIAL
OR SHORT-LIVED CLEARING THROUGH THE FIRST HALF OF THE DAY ON MONDAY
BEFORE THE ARRIVAL OF THE UPPER LOW DYNAMICS BRINGS RENEW MID/UPPER
LEVEL LIFT MONDAY AFTERNOON. MOISTURE WILL BE LIMITED HOWEVER AND
WILL LIKELY SUPPORT ONLY SPRINKLES...AND QUITE POSSIBLY A WET FLAKE
OR TWO ACROSS NORTHERN PORTIONS OF THE FORECAST AREA MONDAY
AFTERNOON. HIGHS IN THE MID TO UPPER 40S NORTH TO LOWER 50S SOUTH
WITH BLUSTERY WESTERLY WINDS OF 20 MPH...GUSTING TO 30 MPH AT TIMES.
EXPECT A BRIEF LULL ACROSS CENTRAL NC IN THE WAKE OF THE UPPER LOW
EXITING OFF THE DELMARVA COAST MONDAY EVENING...BEFORE THE ARRIVAL
OF A STRONG MID/UPPER LEVEL PV ANOMALY INTO THE SOUTHERN APPALACHIANS
BY DAYBREAK TUESDAY. ANY PRECIP SHOULD HOLD OFF UNTIL DAYBREAK
TUESDAY SO WILL KEEP FORECAST DRY WHILE HOLDING ON TO AMPLE CLOUD
COVER. LOWS IN THE UPPER 20 TO LOWER 30S.
TUESDAY AND TUESDAY NIGHT:
THE AFOREMENTIONED STRONG MID/UPPER LEVEL PV ANOMALY WILL MOVE
THROUGH THE CAROLINAS ON A MORE SOUTHERN TRACK THAN THE INITIAL
UPPER LOW PASSAGE THE DAY BEFORE(MONDAY). THIS MORE SOUTHERN TRACK
WILL RESULT IN BETTER CHANCES OF SEEING SOME MEASURABLE PRECIP
ACROSS CENTRAL NC ON TUESDAY. NAM/GFS BUFR BUFKIT SOUNDINGS SHOW A
DECENT SIZE DENDRITIC GROWTH ZONE THAT IS ABOUT 75MB DEEP ACROSS THE
NORTHERN HALF OF THE FORECAST AREA THROUGH MIDDAY TUESDAY(~18Z).
IF THE PRECIP STARTS EARLY ENOUGH IN THE MORNING...NORTHERN PORTIONS
OF THE FORECAST AREA COULD DEFINITELY SEE A QUICK PASSING SNOW
SHOWER...WITH IT BECOMING INCREASING MIXED WITH RAIN LATER INTO THE
DAY AS TEMPERATURES IN THE SHALLOW ABOVE FREEZING LAYER
ONCE AGAIN WARM INTO THE MID-UPPER 40S...TO LOWER 50S SOUTH.
NO ACCUMULATIONS ARE EXPECTED.
CLOUDS WILL FINALLY CLEAR OUT TUESDAY NIGHT WITH PRESSURE GRADIENT
RELAXING AS WELL. LOWS IN THE UPPER 20S TO LOWER 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 315 AM SUNDAY...
WITH THE HIGH-LATITUDE BLOCK REMAINING IN PLACE...TEMPERATURES WILL
BE VERY SLOW TO MODERATE UNDERNEATH THE NEGATIVE HEIGHT ANOMALIES
ANCHORED ALONG THE EASTERN CONUS/WESTERN ATLANTIC. THUS...COOL-BELOW
NORMAL TEMPERATURES WILL CONTINUE THROUGH THE END OF THE WORK
WEEK...WITH AT OR BELOW FREEZING MINS EACH NIGHT. AS HEIGHTS BEGIN
TO INCREASE ALOFT AND THE CANADIAN SFC HIGH SHIFTS EAST OF THE
AREA...DAYTIME TEMPERATURES WILL LOOK TO FINALLY REBOUND INTO THE
LOWER 60S.
DISTURBANCES IN THE NW FLOW ALOFT ON THE BACK-SIDE OF THE UPPER
TROUGH OVER THE WESTERN ATLANTIC COULD BRING EPISODIC CLOUDINESS
BUT IT SHOULD REMAIN DRY THROUGH THE PERIOD.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AS OF 745 AM SUNDAY...
HIGH CONFIDENCE CONTINUES THAT LOW END MVFR/IFR CONDITIONS WILL
OVERSPREAD CENTRAL NC THIS MORNING AND PERSIST FOR MOST OF THE
AFTERNOON AND EVENING HOURS. A LARGE SHIELD OF RAIN WILL CONTINUE TO
OVERSPREAD THE REGION FROM THE SOUTHWEST THIS MORNING. RAIN SHOULD
START AT KRDU WITHIN THE HOUR AND BY 13Z AT KRWI. AFTER THE INITIAL
SURGE...THE WIDESPREAD RAIN WILL EVOLVE TO MORE SHOWER CONDITIONS
WITH LOW END MVFR/IFR CEILINGS AND MVFR VISIBILITIES DURING THE
AFTERNOON. A COLD FRONT WILL MOVE EAST ACROSS CENTRAL NC WELL AFTER
MIDNIGHT TOWARD MONDAY MORNING AND BEGIN ERODING THE LINGERING LOW
CLOUDS AND CEILINGS WILL BEGIN TO RISE TOWARD DAYBREAK..
LOW END MVFR/IFR CONDITIONS ARE EXPECTED TO IMPROVE ON MONDAY
MORNING...ESPECIALLY AFTER DAYBREAK. BUT THE REGION WILL BE IN AN
UNSETTLED PATTERN THAT WILL SUPPORT PERIODS OF SCT-BKN CUMULUS OR
STRATUS WITH MAINLY VFR CEILINGS ON MONDAY THROUGH WEDNESDAY. A RAIN
OR SNOW SHOWER IS POSSIBLE ON MONDAY OR TUESDAY...ESPECIALLY DURING
THE AFTERNOON ACROSS THE NORTH. FAIR WEATHER WITH VFR CONDITIONS ARE
ANTICIPATED ON THURSDAY. -BLAES
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...KC/BLAES
SHORT TERM...CBL
LONG TERM...CBL
AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1059 AM EDT SUN MAR 24 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER THE MISSISSIPPI RIVER VALLEY WILL MOVE
NORTHEAST INTO THE OHIO VALLEY TONIGHT. A SECOND AREA OF LOW
PRESSURE WILL DEVELOP NEAR CAPE FEAR THIS AFTERNOON AND MOVE SLOWLY
UP THE COAST TO NEAR NEW JERSEY BY MONDAY AFTERNOON. A COOL
NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1058 AM SUNDAY...
TODAY:
THE SURFACE LOW THAT DEVELOPED OVER THE SOUTHERN MISSISSIPPI RIVER
VALLEY OVERNIGHT WILL CONTINUE TO SPLIT INTO TWO SEPARATE LOWS AS IT
MOVES NORTH AND EAST THIS MORNING. THE WESTERN MOST LOW WILL DEEPEN
AS IT MOVES NORTHEAST ALONG THE WEST SIDE OF THE APPALACHIANS...
WHILE THE SECOND WILL INTENSIFY OFF THE SE ATLANTIC COAST AND
MIGRATE NE ALONG IT. ALTHOUGH SOME LIGHT TO MODERATE RAIN HAS MOVED
INTO CENTRAL NC THIS MORNING...THE STRONGEST CONVECTION AND HEAVIEST
RAINFALL HAS REMAINED SOUTH OF THE AREA. 12Z UPPER AIR ANALYSES SHOW
THE H85 LOW ALREADY SPLITTING...WITH SOME INDICATION OF THE
SECONDARY LOW AT 700 MB. CENTRAL NC IS UNDER THE RIGHT REAR QUADRANT
OF THE 150+ KT UPPER LEVEL JET...WITH ANOTHER JET...WITH A SECOND
JET...WITH WINDS JUST UNDER 150 KTS...TO THE SOUTHEAST. WHILE
SURFACE WINDS ARE MAINLY ENE TO NE ACROSS THE AREA...UPPER LEVEL
WINDS ARE SOUTH AND SW. AS THE LOW MOVES OFF THE ATLANTIC COAST
UPPER LEVEL WINDS SHOULD BRIEFLY BACK AROUND TO MORE SOUTHEASTERLY
BEFORE THE LOW...INITIALLY TO THE WEST OF THE APPALACHIANS...MOVES
EAST THROUGH THE MID ATLANTIC. THE 10Z HRRR AND THE 00Z HIRES
WRF-ARW CONVECTION ALLOWING MODELS...WHICH ARE CAPTURING THE CURRENT
REFLECTIVITIES BEST...INDICATE AN AREA OF LIGHT RAINFALL FILLING IN
BEHIND THE BREAK...MAINLY ACROSS THE NORTH AND NORTHWEST WITH SOME
SHOWERS POSSIBLE THROUGH TONIGHT. AS SUCH...CONTINUE WITH 100
PERCENT CHANCE FOR RAIN INTO THE AFTERNOON WITH CHANCES GRADUALLY
DECREASING ACROSS THE WEST AND SOUTH THIS AFT/EVE. WHILE RAINFALL
AMOUNTS ARE NOT ENTIRELY CERTAIN...HPC GUIDANCE APPEARS TO BE A BIT
OVERDONE. GIVEN THE DRY SLOT MOVING INTO THE WEST AND THE FORECAST
REFLECTIVITIES FROM THE CONVECTION ALLOWING MODELS...WILL HAVE
RAINFALL AMOUNTS LESS THAN GUIDANCE...WITH HIGHEST TOTALS ACROSS THE
NORTH. -KC
WITH THE HYBRID COLD AIR DAMMING EVENT TODAY AND TONIGHT...
TEMPERATURES WILL FEATURE VERY LITTLE DIURNAL RANGE...ESPECIALLY IN
THE HEART OF THE DAMMING REGION. HIGHS SHOULD RANGE IN THE UPPER 30S
IN THE NW PIEDMONT TO THE MID 40S IN THE SOUTHERN COASTAL PLAIN.
TEMPERATURES TONIGHT WILL FEATURE ONLY A MODEST DROP OFF WITH LOWS
TONIGHT WILL RANGING FROM THE LOWER/MID 30S ACROSS THE NORTHWEST TO
UPPER 30S SOUTHEAST. -BLAES
TONIGHT:
THE LAST BATCH OF SHOWERS...POSSIBLY INCLUDING SOME SHALLOW
CONVECTION WILL SWING EAST AND NORTHEAST THROUGH CENTRAL NC BETWEEN
02-08Z. WITH ANY LINGERING PRECIPITATION HUGGING THE VA BORDER OR
PERHAPS SOME PATCHY DRIZZLE. THERE IS SOME CONCERN THAT THE BOUNDARY
LAYER MAY COOL ENOUGH TO REACH FREEZING ON MONDAY MORNING IN THE
TRIAD AREA WHICH COULD RESULT IN SOME BLACK ICE. WHILE THE NEAR
SURFACE FLOW IS BECOMING SOUTHWEST/WEST AND DRYING...IT APPEARS THAT
SKIES SHOULD REMAIN CLOUDY THROUGH DAYBREAK LIMITING RADIATIONAL
COOLING. SUBSEQUENT SHIFTS WILL NEED TO MONITOR THE POTENTIAL FOR
SOME CLEARING AND A SUDDEN DROP IN SURFACE TEMPS AT DAYBREAK
ALTHOUGH THIS APPEARS UNLIKELY AS TURBULENT MIXING WILL LIKELY BE
ONGOING AND LIMIT SFC COOLING. -BLAES
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 315 AM SUNDAY...
MONDAY AND MONDAY NIGHT:
THE INLAND SFC LOW(OVER THE TN/OH VALLEY)ASSOCIATED WITH THE MILLER
B STORM SYSTEM WILL QUICKLY GIVE WAY TO THE RAPIDLY INTENSIFYING
SECONDARY LOW LIFTING NORTHWARD UP THE MID ATLC COAST MONDAY
MORNING. AS THE SYSTEM GAINS NORTHERN LATITUDE...THE RESULTANT
WEST-NWLY LOW-LEVEL FLOW WILL ADVECT COLDER-DRIER AIR INTO THE
AREA...SCOURING OUT THE RESIDUAL DAMMING AIRMASS LEADING TO PARTIAL
OR SHORT-LIVED CLEARING THROUGH THE FIRST HALF OF THE DAY ON MONDAY
BEFORE THE ARRIVAL OF THE UPPER LOW DYNAMICS BRINGS RENEW MID/UPPER
LEVEL LIFT MONDAY AFTERNOON. MOISTURE WILL BE LIMITED HOWEVER AND
WILL LIKELY SUPPORT ONLY SPRINKLES...AND QUITE POSSIBLY A WET FLAKE
OR TWO ACROSS NORTHERN PORTIONS OF THE FORECAST AREA MONDAY
AFTERNOON. HIGHS IN THE MID TO UPPER 40S NORTH TO LOWER 50S SOUTH
WITH BLUSTERY WESTERLY WINDS OF 20 MPH...GUSTING TO 30 MPH AT TIMES.
EXPECT A BRIEF LULL ACROSS CENTRAL NC IN THE WAKE OF THE UPPER LOW
EXITING OFF THE DELMARVA COAST MONDAY EVENING...BEFORE THE ARRIVAL
OF A STRONG MID/UPPER LEVEL PV ANOMALY INTO THE SOUTHERN APPALACHIANS
BY DAYBREAK TUESDAY. ANY PRECIP SHOULD HOLD OFF UNTIL DAYBREAK
TUESDAY SO WILL KEEP FORECAST DRY WHILE HOLDING ON TO AMPLE CLOUD
COVER. LOWS IN THE UPPER 20 TO LOWER 30S.
TUESDAY AND TUESDAY NIGHT:
THE AFOREMENTIONED STRONG MID/UPPER LEVEL PV ANOMALY WILL MOVE
THROUGH THE CAROLINAS ON A MORE SOUTHERN TRACK THAN THE INITIAL
UPPER LOW PASSAGE THE DAY BEFORE(MONDAY). THIS MORE SOUTHERN TRACK
WILL RESULT IN BETTER CHANCES OF SEEING SOME MEASURABLE PRECIP
ACROSS CENTRAL NC ON TUESDAY. NAM/GFS BUFR BUFKIT SOUNDINGS SHOW A
DECENT SIZE DENDRITIC GROWTH ZONE THAT IS ABOUT 75MB DEEP ACROSS THE
NORTHERN HALF OF THE FORECAST AREA THROUGH MIDDAY TUESDAY(~18Z).
IF THE PRECIP STARTS EARLY ENOUGH IN THE MORNING...NORTHERN PORTIONS
OF THE FORECAST AREA COULD DEFINITELY SEE A QUICK PASSING SNOW
SHOWER...WITH IT BECOMING INCREASING MIXED WITH RAIN LATER INTO THE
DAY AS TEMPERATURES IN THE SHALLOW ABOVE FREEZING LAYER
ONCE AGAIN WARM INTO THE MID-UPPER 40S...TO LOWER 50S SOUTH.
NO ACCUMULATIONS ARE EXPECTED.
CLOUDS WILL FINALLY CLEAR OUT TUESDAY NIGHT WITH PRESSURE GRADIENT
RELAXING AS WELL. LOWS IN THE UPPER 20S TO LOWER 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 315 AM SUNDAY...
WITH THE HIGH-LATITUDE BLOCK REMAINING IN PLACE...TEMPERATURES WILL
BE VERY SLOW TO MODERATE UNDERNEATH THE NEGATIVE HEIGHT ANOMALIES
ANCHORED ALONG THE EASTERN CONUS/WESTERN ATLANTIC. THUS...COOL-BELOW
NORMAL TEMPERATURES WILL CONTINUE THROUGH THE END OF THE WORK
WEEK...WITH AT OR BELOW FREEZING MINS EACH NIGHT. AS HEIGHTS BEGIN
TO INCREASE ALOFT AND THE CANADIAN SFC HIGH SHIFTS EAST OF THE
AREA...DAYTIME TEMPERATURES WILL LOOK TO FINALLY REBOUND INTO THE
LOWER 60S.
DISTURBANCES IN THE NW FLOW ALOFT ON THE BACK-SIDE OF THE UPPER
TROUGH OVER THE WESTERN ATLANTIC COULD BRING EPISODIC CLOUDINESS
BUT IT SHOULD REMAIN DRY THROUGH THE PERIOD.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AS OF 745 AM SUNDAY...
HIGH CONFIDENCE CONTINUES THAT LOW END MVFR/IFR CONDITIONS WILL
OVERSPREAD CENTRAL NC THIS MORNING AND PERSIST FOR MOST OF THE
AFTERNOON AND EVENING HOURS. A LARGE SHIELD OF RAIN WILL CONTINUE TO
OVERSPREAD THE REGION FROM THE SOUTHWEST THIS MORNING. RAIN SHOULD
START AT KRDU WITHIN THE HOUR AND BY 13Z AT KRWI. AFTER THE INITIAL
SURGE...THE WIDESPREAD RAIN WILL EVOLVE TO MORE SHOWER CONDITIONS
WITH LOW END MVFR/IFR CEILINGS AND MVFR VISIBILITIES DURING THE
AFTERNOON. A COLD FRONT WILL MOVE EAST ACROSS CENTRAL NC WELL AFTER
MIDNIGHT TOWARD MONDAY MORNING AND BEGIN ERODING THE LINGERING LOW
CLOUDS AND CEILINGS WILL BEGIN TO RISE TOWARD DAYBREAK..
LOW END MVFR/IFR CONDITIONS ARE EXPECTED TO IMPROVE ON MONDAY
MORNING...ESPECIALLY AFTER DAYBREAK. BUT THE REGION WILL BE IN AN
UNSETTLED PATTERN THAT WILL SUPPORT PERIODS OF SCT-BKN CUMULUS OR
STRATUS WITH MAINLY VFR CEILINGS ON MONDAY THROUGH WEDNESDAY. A RAIN
OR SNOW SHOWER IS POSSIBLE ON MONDAY OR TUESDAY...ESPECIALLY DURING
THE AFTERNOON ACROSS THE NORTH. FAIR WEATHER WITH VFR CONDITIONS ARE
ANTICIPATED ON THURSDAY. -BLAES
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...KC/BLAES
SHORT TERM...CBL
LONG TERM...CBL
AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
639 AM EDT SUN MAR 24 2013
.SYNOPSIS...
BELOW NORMAL TEMPERATURES THROUGH NEXT WEEK. WINTER STORM AFFECTS
THE AREA SUNDAY AND LATE MONDAY...BRINGING MAINLY RAIN SUNDAY...
CHANGING TO ALL SNOW MONDAY NIGHT. UPSLOPE SNOW EVENT FOLLOWS.
&&
.NEAR TERM /THROUGH TONIGHT/...
630 AM UPDATE...FRESHENED UP GRIDS A BIT...BUT NO SIGNIFICANT
CHANGES.
PREVIOUS DISCUSSION...
WHAT A COMPLEX SYSTEM. ON THE POSITIVE SIDE...MODELS AGREE VERY WELL
ON THE MASS AND QPF FIELDS OF THE SYSTEM AFFECTING US THIS PERIOD.
PARENT SURFACE LOW LIFTS NORTHEAST INTO SOUTHERN OHIO AHEAD OF A
DEVELOPING STRONG UPPER LOW OVER THE MID MISSISSIPPI VALLEY...THEN
REDEVELOPS LATER TONIGHT JUST OFF THE MID ATLANTIC COAST AS THE
APPROACHING UPPER SYSTEM TAPS INTO THE GULF STREAM WATERS. LOOKS LIKE
ONE SLUG OF QPF THIS AFTERNOON WITH A LEAD SHORT WAVE AND ANOTHER
TONIGHT WITH THE UPPER LOW ITSELF. HOWEVER...THE THERMAL FIELDS WITH
THE SYSTEM DO NOT AGREE WELL...AND THIS IS CRITICAL TO THE TYPE OF
PRECIP IN A QPF REGIME OF BETWEEN HALF AN INCH AND AN INCH.
NORMALLY...I REPEAT NORMALLY...WITH THE TRACK OF THE PARENT SURFACE
LOW WE WOULD EXPECT A BRIEF PERIOD OF WINTRY MIX TO RAIN IN THE
LOWLANDS AS THE TYPICAL WARM WEDGE IN LOW LEVEL SOUTHEASTERLY FLOW
SURGES AHEAD OF THE LOW. WE WOULD KEEP A WINTRY TYPE PRECIP REGIME
IN THE NORTHERN MOUNTAINS WITH THE TYPICAL UPSLOPE AND COLD AIR
DAMMING. WE WOULD THEN SEE A TRANSITION BACK TO SNOW LATER TONIGHT
AS COLDER AIR WORKS IN ALOFT.
HOWEVER...THE TRACK OF THE UPPER SYSTEM IS EAST RIGHT ACROSS OUR
AREA. THIS PREVENTS THE WARM WEDGE FROM GETTING TOO FAR NORTH THIS
AFTERNOON AS THE HEAVIER PRECIP ARRIVES. THE NAM AND RUC ARE THE
WARM OUTLIER FOR THE WARM WEDGE...WHILE THE GFS AND EURO ARE COLDER.
THIS COLDER SCENARIO APPEARS TO BE DUE TO STRONG UPPER DYNAMICS AND
WET BULBING WHIT THE PRECIP. EVEN THE SREF SHOWS THIS.
AM GOING WITH THE COOLER SCENARIO. YES...THE MAV/LAMP TEMP GUIDANCE
CURIOUSLY SHOW HIGHS IN THE 40S FOR MUCH OF THE LOWLANDS TODAY...BUT
THIS IS DISCOUNTED BY THE GUIDANCE NOT SEEMING TO ACCOUNT FOR WET
BULB COOLING. SO WILL ACTUALLY USE THE COOLER NAM SURFACE TEMPS BUT
THE GFS/EURO AND SREF COOLER TEMPS ALOFT.
ALL THIS PANS OUT TO TEMPS TODAY REMAINING IN THE 30S ACROSS THE
MOST OF THE LOWLANDS...WHILE BELOW FREEZING TEMPS OCCUR IN THE
NORTHERN MOUNTAINS. THIS WILL BE COLD ENOUGH FOR ALL SNOW NORTHERN
MOUNTAINS...SNOW WITH MIXED RAIN AND SLEET ACROSS THE FAR
NORTH...AND BRIEF WINTRY MIX TO RAIN ELSEWHERE. WITH THE AMOUNT OF
QPF...COULD BE HEAVY WET SNOW ACROSS THE FAR NORTH. THUS...ISSUED A
WINTER WEATHER ADVISORY FOR THE AREA LATER THIS AFTERNOON AND
ESPECIALLY TONIGHT WITH THE SECOND QPF SLUG. WINTER STORM WARNING
REMAINS IN EFFECT FOR THE NORTHERN MOUNTAINS.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
LOW PRESSURE SYSTEM EXITS TO THE EAST...ONLY TO HAVE CYCLONIC FLOW
REINFORCED BY A SECONDARY TROUGH SWINGING THROUGH THE TENNESSEE
VALLEY INTO THE MID ATLANTIC. IN THE LOWER LEVELS...FLOW WILL TURN
AROUND TO THE NORTHWEST THAT WILL EVENTUALLY TAP INTO SOME GREAT
LAKES MOISTURE. COLD POOL ALOFT WILL SETTLE INTO THE AREA...AND WILL
NOT RELINQUISH ITS GRIP ALL THE WAY INTO MID WEEK...WITH 850MB
TEMPERATURES VARYING FROM -7C TO -10C. IN THE END...THIS RESULTS IN
POPS FOR THE BULK OF THE SHORT TERM FORECAST ENHANCED BY THE
AFOREMENTIONED SECONDARY TROUGH AXIS MONDAY EVENING INTO
TUESDAY...AND THEN THE CONVECTIVE NATURE OF THE NORTHWEST FLOW INTO
WEDNESDAY.
UNDERCUT THE GUIDANCE FOR THE DAYTIME MAXIMUM TEMPERATURES GIVEN THE
CLOUD COVER...PRECIPITATION...NORTHWESTERLY FLOW...AND COLD POOL
ALOFT. WITH THAT BEING SAID...GIVEN THE TIME OF YEAR...BEST CHANCE
FOR SNOW ACCUMULATIONS WILL BE DURING THE OVERNIGHT HOURS. HAVE
DAYTIME TEMPERATURES CLIMBING ABOVE FREEZING IN MOST
CASES...ALTHOUGH THE MOUNTAINS WILL HOVER AROUND FREEZING OR STAY
BELOW IN THE CASE OF THE HIGHER ELEVATIONS OF THE NORTHEAST
MOUNTAINS. SO...EXPECT SOME MELTING DURING THE DAY...WITH SUN ANGLE
AND LONGER DAYS THAN NIGHTS ALSO CONTRIBUTING TO THIS EQUATION.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
USED THE ECMWF ENSEMBLE MEAN THROUGH THE PERIOD. SOME UPSLOPE SNOW
SHOWERS REMAIN A POSSIBILITY TUESDAY NIGHT INTO EARLY THURSDAY. HIGH
PRESSURE THEN BUILDS IN FOR THURSDAY NIGHT AND FRIDAY. A LOW
CONFIDENCE SYSTEM THEN SLIDES SOUTH OF THE AREA FRIDAY NIGHT AND
SATURDAY...CAUSING SOME SMALL POPS OVER OUR FORECAST AREA.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
12Z SUNDAY THRU 12Z MONDAY...
VFR THRU 12Z WITH INCREASE IN MID/HI CLDS OVERNIGHT.
CIGS WITH ASSOC PRECIP WILL BE RAPIDLY PUSHING NORTHEASTWARD ACROSS
THE AREA...WITH MUCH OF THE AREA FALLING THROUGH MVFR CIGS AND INTO
IFR CIGS AFTER PRECIP BEGINS. A MIX OF RA/SN FOR KHTS-KCRW-KBKW 15
TO 18Z WITH SOME IFR VSBY WHERE PCPN STAYS MAINLY SN. A SWITCH TO RA
IN AFTN CENTRAL AND SOUTHERN LOW LANDS WITH PERHAPS SOME IMPROVEMENT
IN CIGS INTO MVFR. AS PCPN PUSHES N...IFR CONDITIONS IN MAINLY SN
DEVELOP AFTER 18Z FOR N TAF SITES...ESPECIALLY NORTHERN AND CENTRAL
MOUNTAINS.
AFTER 00Z...MAINLY IFR. WINTRY PRECIP CONTINUES NORTHERN AND
CENTRAL MOUNTAINS...WHILE MIXED PRECIP CHANGES TO SNOW BY 06Z
ELSEWHERE.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY...
FORECAST CONFIDENCE...MED TO HIGH.
ALTERNATE SCENARIOS: TIMING OF SUB-VFR CIGS AND ONSET OF PRECIP MAY
VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18
CRW CONSISTENCY H H H H M M L M M M M M
HTS CONSISTENCY H H H H H H L M M M H L
BKW CONSISTENCY H H H L M M M M M M M M
EKN CONSISTENCY H H H H H H L L L L M M
PKB CONSISTENCY H H H H H H H H H M M M
CKB CONSISTENCY H H H H H H H H L L M M
AFTER 12Z MONDAY...
IFR CONDITIONS POSSIBLE IN SNOW SHOWERS MONDAY AND TUESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 11 AM EDT
MONDAY FOR WVZ010-011-020-031-032-039-040.
WINTER STORM WARNING FROM NOON TODAY TO 2 PM EDT TUESDAY FOR
WVZ038-046-047.
OH...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 11 AM EDT
MONDAY FOR OHZ066-067-075-076-084.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JMV/26
NEAR TERM...JMV
SHORT TERM...26
LONG TERM...RPY
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
1002 AM EDT SUN MAR 24 2013
.DISCUSSION...INITIAL ROUND OF SHOWERS HAS MOVED THROUGH MOST OF THE
FORECAST AREA THIS MORNING. DRY SLOT NOW MOVING IN WILL REQUIRE
LOWERING RAIN CHANCES FOR AT LEAST A FEW HOURS. LATEST RUC MODEL
SPREADS MORE SHOWERS OUR WAY BEFORE HEAVIER SHOWERS AND ISOLATED
THUNDERSTORMS OCCUR WITH THE FRONTAL BOUNDARY BY MID TO LATE
AFTERNOON. FREEZING LEVEL QUITE LOW ALREADY FOR LATE MARCH AND WILL
LOWER EVEN MORE AS COLDER AIR APPROACHES THIS AFTERNOON AND EVENING.
SEVERE THREAT SHOULD BE MAINLY LARGE HAIL WITH STRONGEST STORMS THAT
DEVELOP.
WINTRY WEATHER PARTS OF FORECAST LOOK ON TRACK FOR NOW. SYNOPTIC
SCALE FORCING IS GONE AFTER MONDAY MORNING...LEAVING A PROLONGED
PERIOD OF NW FLOW WITH UPSLOPE LOW LEVEL FORCING. MOISTURE LOOKS
DEEP AND LAPSE RATES ARE QUITE STEEP ON MONDAY AFTERNOON...WITH EVEN
MORE INSTABILITY (CAPES OF AROUND 100 J/KG) NOTED FOR TUESDAY
DAYTIME. OUTSIDE OF THE WATCH AREA...THINK BANDS OF SNOW SHOWERS
WILL PROVIDE A HIT OR MISS PATTERN OF LIGHT SNOW ACCUMULATIONS...AND
GENERALLY MEETING ADVISORY CRITERIA OR LESS. WILL DEFER ANY CHANGES
BEYOND TODAY TO THE AFTERNOON PACKAGE.
UPDATED GRIDS AND PRODUCTS BY AROUND 11 AM EDT.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 61 36 43 32 44 / 100 50 20 10 30
KNOXVILLE AIRPORT, TN 57 36 42 31 42 / 100 60 40 40 30
OAK RIDGE, TN 57 36 42 32 41 / 100 60 40 40 30
TRI CITIES AIRPORT, TN 52 32 38 31 39 / 100 80 60 70 40
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR THE FOLLOWING ZONES: BLOUNT SMOKY MOUNTAINS...COCKE
SMOKY MOUNTAINS...JOHNSON...SEVIER SMOKY MOUNTAINS...
SOUTHEAST CARTER...SOUTHEAST GREENE...UNICOI.
VA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR THE FOLLOWING ZONES: LEE...RUSSELL...SCOTT...
WASHINGTON...WISE.
&&
$$
TG
AREA FORECAST DISCUSSION...CORRECTED
NWS DENVER/BOULDER CO
237 PM MDT SUN MAR 24 2013
...CORRECTED SPELLING ERRORS...
.SHORT TERM...A DISTURBANCE IN NW FLOW ALOFT WILL MOVE ACROSS THE
AREA THIS EVENING AS A BNDRY BRIEFLY ENHANCES UPSLOPE FLOW ALONG
THE FRONT RANGE. LAPSE RATES IN AND NR THE FOOTHILLS WILL BE
AROUND 8 C/KM. THUS WOULD EXPECT SNOW SHOWER ACTIVITY THRU THE
EARLY EVENING HOURS. BOTH THE RAP AND HRRR ARE SHOWING AMOUNTS IN
THE FOOTHILLS WEST AND SOUTHWEST OF DENVER UP TO 4 INCHES WITH UP
TO 2 INCHES IN THE WRN SUBURBS. FURTHER EAST AMOUNTS ARE IN AN
INCH OR LESS. ANOTHER AREA OF SNOW MAY RESIDE NR THE WY-CO BORDER
IN NR WELD COUNTY WHERE AN INCH OR TWO MAY FALL. IN THE MTNS WILL
CONTINUE TO SEE SOME OROGRAPHIC -SHSN WITH A FEW INCHES POSSIBLE
AS WELL. BY MIDNIGHT MOST ACTIVITY SHOULD END ALTHOUGH RAP SHOWS
SHOW LIGHT ACTIVITY NR THE WY BORDER.
ON MON DRIER AIR WILL BE OVER THE AREA IN NW FLOW ALOFT HOWEVER
SOME LINGERING MOISTURE IN THE MTNS MAY ALLOW FOR A SLIGHT CHC OF
-SHSN. AS FOR TEMPS WITH SFC HIGH PRES STILL OVER THE AREA AND
LINGERING SNOWPACK WILL KEEP HIGHS MAINLY IN THE UPPER 20S TO
LOWER 30S ACROSS NERN CO.
.LONG TERM...NORTHWESTERLY FLOW ALOFT IS TO DOMINATE THE FORECAST
AREA MONDAY NIGHT THROUGH TUESDAY...THEN UPPER RIDGING GETS OVER
THE STATE AND THE FLOW ALOFT IS ZONAL. THE SYNOPTIC SCALE ENERGY
PROGGED OVER THE CWA IS BENIGN ACCORDING TO THE Q-G VERTICAL
VELOCITY FIELDS MONDAY NIGHT THROUGH WEDNESDAY NIGHT. THE LOW
LEVEL WIND AND PRESSURE FIELDS SHOW NORMAL DIURNAL TRENDS
CONCERNING THE BOUNDARY LAYER WINDS MONDAY NIGHT THROUGH WEDNESDAY
NIGHT. MODELS HAVE LIMITED MOISTURE AROUND MONDAY NIGHT. ON
TUESDAY...MOISTURE INCREASES OVER THE MOUNTAINS AND IN THE MID AND
UPPER LEVELS OF THE PLAINS...ESPECIALLY ON THE GFS. THIS CONTINUE
INTO WEDNESDAY...BEFORE DRYING OUT SOMEWHAT WEDNESDAY NIGHT. THE QPF
FIELDS HAVE MINIMAL MEASURABLE PRECIPITATION NOTED...MOSTLY OVER THE
MOUNTAINS...TUESDAY AFTERNOON...THEN AGAIN WEDNESDAY INTO WEDNESDAY
EVENING. WILL GO WITH 20-40% POPS IN THE MOUNTAINS TUESDAY AFTERNOON
THROUGH WEDNESDAY EVENING. FOR TEMPERATURES... TUESDAY`S HIGHS ARE
ABOUT 6 C WARMER THAN MONDAY`S HIGHS. WEDENSDAY`S HIGHS ARE 1-3 C
WARMER THAN TUESDAY`S. FOR THE LATER DAYS...THURSDAY THROUGH
SUNDAY...NOW THE MODELS KEEP UPPER RIDGING OVER COLORADO ALL FOUR
DAYS. THE UPPER CLOSED LOW STAYS WELL WEST OF THE THE STATE THROUGH
SUNDAY ON THESE LATEST RUNS.
&&
.AVIATION...WILL STILL SEE A CHC OF SNOW SHOWERS THU 02Z WITH
ACCUMULATIONS AT DIA AN INCH OR LESS. AFER 02Z SNOW CHANCES SHOULD
DIMINISH WITH ONLY A FEW FLURRIES POSSIBLE. CEILINGS AND
VISIBILITIES MAY STILL DROP DOWN TO MVFR LVLS DUE TO SNOW THRU
02Z. AFTER 02Z WILL KEEP CEILINGS AROUND 6000 FT THRU 07Z. WINDS
SHOULD BE NNE THRU THE EARLY EVENING BUT THEN BECOME LIGHT SSWLY
AFTER 03Z THRU MON MORNING. ON MON EXPECT VFR CONDITIONS WITH
LIGHT SSE WINDS BY AFTN.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....RJK
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
520 PM CDT SUN MAR 24 2013
.DISCUSSION...
305 PM CDT
SHORT TERM...SNOW STORM MOVING THROUGH THE MIDWEST TONIGHT INTO
MONDAY...
WINTER STORM WARNING/WINTER WEATHER ADVISORY HEADLINES CONTINUE
UNCHANGED. BUMPED SNOW AMOUNTS IN WARNING AREA SLIGHTLY...WITH
LOCALIZED 7-8 INCH NOT OUT OF THE QUESTION THERE.
MID-AFTERNOON FINDS SURFACE LOW PRESSURE OVER THE LOWER OHIO VALLEY
REGION...AND WELL-DEFINED CLOSED LOW ACROSS SOUTHEAST MISSOURI IN
GOES WATER VAPOR IMAGERY. NICE 4-5 MB PRESSURE RISE/FALL COUPLET
ASSOCIATED WITH THE SURFACE LOW...INDICATING SOME DEEPENING STILL
OCCURRING. CLASSIC COMMA SHAPE TO RADAR PRESENTATION IN REGIONAL
MOSAIC...WITH DEFORMATION BAND EXTENDING FROM CENTRAL MISSOURI
ACROSS CENTRAL IL AT 230 PM. PLENTY OF 3/4SM TO 1/4SM VISIBILITY
REPORTS IN MODERATE/HEAVY SNOW WITHIN THIS BAND PER METARS...WITH
HEAVIEST SNOW POISED TO AFFECT WFO CHICAGO WINTER STORM WARNING AREA
VERY SHORTLY. SEVERAL 6-8 INCH SNOWFALL REPORTS HAVE BEEN RECEIVED
FROM UPSTREAM AREAS IN MO/WESTERN IL. A FEW CLOUD-GROUND LIGHTNING
STRIKES CONTINUE TO BE NOTED AHEAD OF THE UPPER LOW...AS NEARBY AS
NORTH OF DECATUR WITHIN THE PAST 30 MINUTES.
OVERALL...LITTLE CHANGE TO FORECAST FROM EARLIER MORNING UPDATE.
SOME TWEAKS MADE WERE TO ADJUST QPF/SNOWFALL AMOUNTS ACROSS THE
ADVISORY/WARNING AREA...BASED ON SEVERAL RECENT MODEL RUNS DEPICTING
UPWARDS OF 0.50 INCHES OF LIQUID EQUIVALENT ACROSS THE SOUTHERN
PORTIONS OF OUR SOUTHERN TIER OF COUNTIES THROUGH THIS EVENING. HAVE
ALSO ADDED A MENTION OF ISOLATED THUNDER ACROSS THIS SAME AREA
THROUGH THE REMAINDER OF THE AFTERNOON HOURS...WITH MODEL DEPICTIONS
OF STEEP MID/UPPER LEVEL LAPSE RATES AND WEAK ELEVATED CAPE AS WELL
AS GRADIENT OF NEGATIVE SATURATED EPV ACROSS THE AREA INTO EARLY
EVENING. HAVE ENDED UP ADDING ABOUT AN INCH OVERALL TO OUR FAR SOUTH
AREA...WHILE DECREASING AMOUNTS FARTHER NORTH AND TRYING TO SHARPEN
UP THE GRADIENT FROM NOT MUCH SNOW TO SIGNIFICANT SNOW SOUTH OF
INTERSTATE 80 CORRIDOR. HEAVIEST SNOW EXPECTED TO OCCUR FROM THE
REMAINDER OF THE AFTERNOON HOURS INTO EARLY EVENING...BEFORE
TAPERING OFF TO LIGHT SNOW BY LATE EVENING/OVERNIGHT.
PERHAPS THE HARDEST PART OF FORECAST IS WITH THE LAKE EFFECT SNOW
POTENTIAL ACROSS NORTHEAST IL/NORTHWEST IND LATER TONIGHT AND
MONDAY. STRONG NORTHEAST WINDS WILL CONTINUE TO PROVIDE MOISTURE
CONVERGENCE AND FLUX OFF OF THE LAKE DURING THE PERIOD...THOUGH
FORECAST SOUNDINGS CONTINUE TO SHOW GENERALLY MARGINAL THERMODYNAMIC
PARAMETERS FOR STRONGER LAKE EFFECT SNOW. DELTA T VALUES GRADUALLY
INCREASE TO ONLY 13/14 DEG C THROUGH MONDAY AFTERNOON...WITH
INVERSION HEIGHTS SLOWLY RISING TO NEAR 7000 FT AGL LATE TONIGHT AND
MONDAY. THIS SHOULD SUPPORT INITIALLY WEAK MULTI-BAND LES INTO
EASTERN WI/NORTHEAST IL...THOUGH ACCUMULATION IS NOT EXPECTED TO BE
OF MUCH SIGNIFICANCE GIVEN WEAK THERMAL PROFILES.
AWAY FROM THE LAKE...STEEP LOW LEVEL LAPSE RATES IN BROAD AREA OF
COOL CYCLONIC FLOW WEST OF DEPARTING STORM WILL LIKELY SUPPORT
SCATTERED FLURRIES AND LIGHT SNOW SHOWERS MONDAY...BUT AGAIN WITH
LITTLE/NO ORGANIZED ACCUMULATION EXPECTED.
BLEND OF MOS TEMPS GENERALLY ACCEPTED TONIGHT/MONDAY...THOUGH WENT A
LITTLE ABOVE GUIDANCE IN A FEW SPOTS TONIGHT WITH PERSISTENT CLOUD
COVER.
RATZER
MEDIUM/LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY...
MONDAY NIGHT THROUGH TUESDAY...LAKE EFFECT SNOW SHOWERS WILL BE THE
MAIN CONCERN THROUGH TUESDAY. THE UPPER LOW WILL BE STEADILY MOVING
EASTWARD INTO THE ATLANTIC BUT A BROAD TROUGH/CYCLONIC FLOW WILL
EXPAND WELL TO THE WEST OF THE MAIN SYSTEM LEAVING THE LOCAL AREA
UNDER A NORTHWEST UPPER FLOW. WEAK UPPER RIDGING WILL BE IN PLACE
OVER THE FAR WESTERN U.S. BUT THIS LOOKS TO BE INTERRUPTED BY ENERGY
TRANSLATING THROUGH IT FROM THE EASTERN PACIFIC. HIGH PRESSURE WILL
BE SPRAWLED ACROSS THE MID SECTION OF NORTH AMERICA WHICH WILL KEEP
NORTHERLY LOW LEVEL FLOW IN PLACE LOCALLY. THIS WILL KEEP AIR
MARGINALLY COLD ENOUGH FOR LAKE EFFECT TO REMAIN IN PLACE MONDAY
NIGHT AND TUESDAY. LAKE TO H85 DELTA T/S GENERALLY RANGE FROM 11 TO
13C DURING THE PERIOD WITH INVERSION HEIGHTS HOVERING AROUND 5000 FT
WITH FLUCTUATIONS ABOVE AND BELOW THAT AT TIMES. THE FETCH REMAINS
FAVORABLE FOR ANY SNOW SHOWERS TO AFFECT FAR EASTERN COOK/WILL AND
LAKE INDIANA AND WESTERN PORTER MONDAY EVENING WITH A SLOW SHIFT
EASTWARD INTO THE OVERNIGHT HOURS. LATE MONDAY EVENING/MONDAY NIGHT
MAY BE THE PEAK TIME FOR LAKE EFFECT SNOW SHOWERS AS INVERSION
HEIGHTS ARE EXPECTED TO RISE TO 6000 OR POSSIBLY NEAR 7000 FT WITH
DELTA T/S AROUND 12C. WILL CARRY HIGHEST CHANCE POPS FOR THIS PERIOD
WITH LAKE COUNTY INDIANA AND PORTER COUNTY THE FOCUS AREAS. ASSUMING
SNOW SHOWERS DO BECOME SOMEWHAT ORGANIZED...SOME LIGHT ACCUMULATION
IS POSSIBLE...PROBABLY ON THE ORDER OF AN INCH OR MAYBE 2 BUT DO NOT
HAVE THE GREATEST CONFIDENCE IN AMOUNTS. WINDS GAIN ENOUGH OF A
WESTERLY COMPONENT TO GRADUALLY SHIFT THE FOCUS EASTWARD THROUGH THE
DAY ON TUESDAY. LAKE PARAMETERS BECOME LESS FAVORABLE THOUGH STILL
MARGINALLY SUPPORTIVE FOR ACTIVITY TUESDAY BUT SURFACE TEMPS WILL
WARM ABOVE FREEZING SO ACCUMULATION WILL BE TOUGH TO COME BY. AT
THIS POINT THE FOCUS WILL LIKELY BE ACROSS PORTER
COUNTY...ESPECIALLY EAST BUT WILL ONLY CARRY MID CHANCE POPS FOR
NOW. IT DOES APPEAR THAT WINDS WILL TURN NORTHWESTERLY ENOUGH TO
THEN PUSH ANY SNOW SHOWERS EAST OF PORTER COUNTY TUESDAY EVENING.
BEYOND THE LAKE EFFECT AREAS...A MIX OF SUN AND CLOUDS IS EXPECTED
TUESDAY WITH SOME EVIDENCE OF A WEAK SHORTWAVE DROPPING ACROSS THE
AREA. HIGHS WILL CONTINUE TO BE CHILLY IN THE UPPER 30S...BUT IF
ENOUGH SUNSHINE CAN PEAK THROUGH A FEW SPOTS COULD SEE 40...MAINLY
IN THE WEST.
WEDNESDAY THROUGH SUNDAY...THE OVERALL PATTERN REALLY WON/T CHANGE
MUCH ACROSS THE MIDWEST WITH NORTHWESTERLY FLOW CONTINUING ALOFT.
RIDGING WILL BUILD ACROSS THE ROCKIES THROUGH LATE WEEK WHICH WILL
HELP PUSH WARMER AIR ALOFT EASTWARD RESULTING IN MODERATING TEMPS
ACROSS THE LOCAL AREA. H85 TEMPS WARM TO AROUND -4C BY LATE THURSDAY
BUT SURFACE HIGH PRESSURE WILL BE RIGHT OVERHEAD. LAKE BREEZE
DEVELOPMENT APPEARS LIKELY WEDNESDAY...AND ESPECIALLY THURSDAY SO
AREAS NEAR THE LAKE WILL BE HELD INTO THE UPPER 30S TO AROUND 40 FOR
HIGH WEDNESDAY AND THURSDAY WHILE THE REST OF THE AREA WARMS TO
AROUND 40 WEDNESDAY AND INTO THE MID 40S...IF NOT A LITTLE
HIGHER...THURSDAY. AREAS WITH THE GREATEST SNOW COVER FROM
TODAY/TONIGHT WILL LIKELY BE ON THE LOWER END OF THOSE RANGES BUT
THIS WILL BECOME MORE CLEAR ONCE EXTENT/AMOUNT OF SNOW COVER IS
KNOWN IN THE MORNING. AT THIS POINT...THE TRACK OF ANY SHORTWAVES
LOOKS TO REMAIN SOUTHWEST OF THE AREA SO DRY WEATHER IS EXPECTED.
RIDGING CONTINUES TO EXPAND EASTWARD THROUGH SATURDAY BRINGING
FURTHER BUT STILL MODEST WARM ADVECTION INTO THE AREA ALOFT SO THE
WARMING TREND WILL LIKELY CONTINUE. H85 TEMPS WILL BE CLOSE TO -2C
SATURDAY AND A SOUTHWESTERLY WIND WILL HAVE SET UP BEHIND HIGH
PRESSURE DEPARTING TO THE SOUTHEAST. THIS MAY PUSH TEMPS AT LEAST
CLOSE TO IF NOT ABOVE NORMAL. A CUTOFF UPPER LOW WILL BE IN PLACE
OFF THE CALIFORNIA COAST BY THIS TIME WITH ANOTHER TROUGH OVER
ALASKA. SHORTWAVE ENERGY LOOKS TO EJECT FROM THE ALASKA TROUGH AND
TRACK SOUTHEAST THROUGH THE CONTINUED NORTHWESTERLY UPPER FLOW AND
AFFECT THE AREA SATURDAY NIGHT OR SUNDAY WITH THE ECMWF AND GFS
ACTUALLY IN VERY GOOD AGREEMENT WITH THIS. DETAILS OF THIS MAY
CHANGE BUT A SYSTEM SUCH AS THIS MAKES SENSE GIVEN THE MORE ACTIVE
FLOW OVER THE PACIFIC AND THE EASTWARD ADVANCEMENT OF THE UPPER
RIDGE PUSHING THE STORM TRACK FURTHER NORTH AND EAST. WILL CARRY
CHANCE POPS FOR SATURDAY NIGHT AND SUNDAY FOR NOW.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* SNOW DEVELOPING OVER NORTHEASTERN IL THIS EVENING AND POTENTIAL
IMPACTS DUE TO VSBY/ACCUMULATIONS.
* GUSTY NORTHEAST WINDS AROUND 30 KT GRADUALLY BACKING TO NORTH.
* LAKE EFFECT SNOW SHOWERS DEVELOPING THIS EVENING AND OVERNIGHT.
BMD/IZZI
//DISCUSSION...UPDATED 22Z...
CLOSELY WATCHING DEVELOPING AREA OF SNOW OVER NORTH CENTRAL
ILLINOIS...WITH SIGNS OF THIS BAND ATTEMPTING TO DEVELOP EASTWARD
TOWARD CHICAGO IN SOME OF THE HIGHER RADAR ELEVATION ANGLES. AN
ACARS SOUNDING OUT OF MDW AT 2106Z INDICATED ABOUT A 4500FT DEEP
LAYER OF SUBSATURATED AIR FROM 045-090...BUT AIR WASNT ESPECIALLY
DRY SO CONTINUED VIRGA INTO THIS LAYER COULD RESULT IN A RATHER
QUICK SATURATION AND EASTWARD DEVELOPMENT OF THE SNOW BAND. THE
DEVELOPING BAND OF SNOW APPEARS TO BE LIFTING NORTH AND
DEVELOPMENT COULD STILL BE NORTH OF ORD BY THE TIME IT FILLS
IN...THOUGH SOME INCREASE IN ECHOS ALOFT ALSO NOTED OVER WILL
COUNTY. PLAN TO PUSH THE TIMING OF THE TEMPO UP ABOUT AN HOUR AND
THE PREVAILING FLURRIES UP A HALF HOUR...BUT OTHERWISE WILL RIDE
WITH GOING FORECAST FOR NOW AND CLOSELY MONITOR RADAR/OBSERVATION
TRENDS THE NEXT COUPLE HOURS.
IZZI
UPDATED 20Z...
EARLIER BAND OF SNOW MENTIONED OVER NORTH CENTRAL ILLINOIS FELL
APART QUICKER THAN ORIGINALLY ANTICIPATED RESULTING IN SNOW BEING
PUSHED BACK SEVERAL HOURS THIS AFTERNOON IN THE TAFS. ANOTHER
BAND OF SNOW LIFTING NORTH INTO THE I-80 CORRIDOR WILL LIKELY
SUFFER A SIMILAR FATE AS IT PUSHES INTO DRY AIR AND OVERALL
FORCING DIMINISHES. LATEST RAP/HRRR HOURLY GUIDANCE STILL TRY TO
BRING SOME PRECIP INTO THE CHICAGO TERMINALS EARLY THIS
EVENING...WITH HRRR STILL HINTING AT LAKE ENHANCEMENT.
PREVIOUS 18Z DISCUSSION...
TRICKY FORECAST THIS AFTERNOON DEALING WITH WHAT WILL LIKELY BE A
SHARP CUTOFF OF HEAVY SNOW ACCUMULATIONS WHICH ARE EXPECTED TO BE
SOUTH OF INTERSTATE 80 TO A DUSTING OR LESS ACROSS FAR NORTHERN
ILLINOIS. AFTERNOON RADAR IMAGERY SHOWS AN BATCH OF MODERATE SNOW
MOVING INTO NORTH CENTRAL ILLINOIS ON ITS WAY TOWARDS THE CHICAGO
TERMINALS 20-21Z. THIS AREA IS PRODUCING SNOW DROPPING VSBY TO
LESS THAN A MILE CURRENTLY...HOWEVER EXPECT THIS TO STRUGGLE TO
HOLD TOGETHER AS IT LIFTS INTO DRIER AIR AND AS OVERALL FORCING
DIMINISHES OVER NORTHERN ILLINOIS. LATEST SHORT TERM HOURLY
GUIDANCE AS WELL AS NAM AND SEVERAL HI-RES WRF RUNS ARE ALL IN
GOOD AGREEMENT KEEPING HEAVIEST QPF AXIS ALONG AND SOUTH OF
INTERSTATE 80. MANY OF THESE MODELS KEEP ORD/MDW DRY ALTOGETHER
WHILE OTHERS BRING UP A FEW HUNDREDTHS OF LIQUID EQUIVALENT
PRECIP. GIVEN RADAR TRENDS CANT RULE OUT A LIGHT DUSTING OF SNOW
AT THE TERMINALS THIS AFTERNOON...NOR A BRIEF DROP TO IFR
VSBY...HOWEVER THINK THIS TO BE UNLIKELY AS OF TAF ISSUANCE.
BREEZY NORTHWESTERLY WINDS WILL CONTINUE THROUGH THE REST OF THE
DAY INTO TONIGHT...LIKELY PICKING UP TO AROUND 30 KT THIS
AFTERNOON AND TAPERING SLIGHTLY LATE IN THE EVENING.
FOCUS WILL BE ON LAKE ENHANCED OR LAKE EFFECT SNOW THIS EVENING.
WIND TURNS TO NNE AROUND 00Z THIS EVENING WITH SHALLOW LAKE INDUCED
INSTABILITY POTENTIALLY ENHANCING OR DEVELOPING NEW SHOWERS.
EQUILIBRIUM LEVELS ARE MEAGER INITIALLY...BUT GRADUALLY DEEPEN TO
AROUND 070 BY 10Z AS THE WINDS VERY SLOWLY CONTINUE TO BACK TO THE
NORTH. CAN SEE THE LAKE EFFECT SIGNATURE IN SOME OF THE RAW GUIDANCE
OUTPUT INCLUDING THE GFS/ECMWF AND GEM...BUT PINNING DOWN THE
DETAILS IS HARD SINCE NONE OF THE HIGHER RES GUIDANCE SEEMS TO HINT
AT IT...EXCEPT FOR THE HRRR. THERE IS POTENTIAL FOR SOME LIGHT
ACCUMULATIONS AND IF A BAND DOES GET GOING COULDNT RULE OUT A QUICK
INCH IN SOME PLACES...BUT THINK THAT GIVEN THE MARGINAL THERMAL
CONDITIONS THIS MAY AMOUNT TO LITTLE MORE THAN VERY LIGHT SNOW OR
FLURRIES.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN SNOW THIS EVENING
* LOW CONFIDENCE IN TIMING/IMPACTS OF LAKE EFFECT SNOW THIS EVENING.
* MMEDIUM CONFIDENCE IN CIG TRENDS.
* HIGH CONFIDENCE IN WIND TRENDS.
IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY...MVFR CIGS LIKELY. CHANCE OF LAKE EFFECT SNOW SHOWERS.
TUESDAY...MVFR CIGS.
WEDNESDAY...VFR.
THURSDAY AND FRIDAY...VFR.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...MVFR CIGS LIKELY. CHANCE OF LAKE EFFECT SNOW
SHOWERS.
TUESDAY...MVFR CIGS.
WEDNESDAY THROUGH SATURDAY...VFR.
TRS
&&
.MARINE...
153 PM CDT
THE MAIN WEATHER CONCERNS THROUGH THE PERIOD CONTINUE TO FOCUS ON
THE SIGNIFICANT STORM SYSTEM AFFECTING THE LAKE TONIGHT THROUGH
MONDAY. WINDS HAVE BEGAN INCREASING UP TO 25 TO 30 KT OUT OF THE
EAST-NORTHEAST ALREADY IN RESPONSE TO AN AREA OF DEEPENING LOW
PRESSURE MOVING EAST-NORTHEASTWARD ACROSS WESTERN KENTUCKY EARLY
THIS AFTERNOON. THIS LOW WILL CONTINUE ACROSS THE OHIO VALLEY
TONIGHT...THEN MERGE WITH A NEW LOW MOVING UP THE CENTRAL ATLANTIC
COAST LATER MONDAY. IT APPEARS THE WINDS WILL CONTINUE TO INCREASE
OVER THE NEXT SEVERAL HOURS...WITH GALES OF 35 TO 40 KT BECOMING
LIKELY BY LATE AFTERNOON ACROSS THE FAR SOUTHERN END OF LAKE
MICHIGAN. LATE TONIGHT AND INTO MONDAY THE FLOW WILL TURN MORE
NORTHERLY AS THE LOW MOVES ACROSS THE OHIO VALLEY. IT APPEARS SOME
GALES COULD PERSIST INTO THE EARLY MORNING HOURS...BEFORE EASING
SLIGHTLY TO 30 KT. I UPGRADED THE SMALL CRAFT ADVISORY TO A GALE
WARNING FOR THE ILLINOIS AND INDIANA SHORES...AND I INCLUDED THE
OPEN WATERS OF FAR SOUTHERN LAKE MICHIGAN FOR LATE THIS AFTERNOON
THROUGH MONDAY MORNING.
THE LONG NORTHERLY FETCH WILL RESULT IN SOME VERY HIGH WAVES ACROSS
THE SOUTHERN END OF THE LAKE...INCLUDING THE NEAR SHORE WATERS.
THESE LARGE WAVES WILL LIKELY PROLONG HAZARDOUS CONDITIONS FOR SMALL
CRAFT FOR BOTH THE ILLINOIS AND THE INDIANA NEAR SHORE WATERS BEYOND
THE GALE PERIOD. HOWEVER...CONDITIONS WILL BEGIN TO IMPROVE BY MID
WEEK AS A SURFACE RIDGE OF HIGH PRESSURE APPROACHES THE WESTERN
LAKES. THIS WILL LIKELY RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS INTO THE END OF THE WEEK.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ033-ILZ039 UNTIL 7 AM MONDAY.
WINTER WEATHER ADVISORY...ILZ023-ILZ032 UNTIL 7 AM MONDAY.
IN...WINTER WEATHER ADVISORY...INZ010-INZ011 UNTIL 7 AM MONDAY.
WINTER STORM WARNING...INZ019 UNTIL 7 AM MONDAY.
LM...GALE WARNING...LMZ080-LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ876-LMZ878 UNTIL 10 AM MONDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...10 AM MONDAY TO 7 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
307 PM CDT SUN MAR 24 2013
.DISCUSSION...
305 PM CDT
SHORT TERM...SNOW STORM MOVING THROUGH THE MIDWEST TONIGHT INTO
MONDAY...
WINTER STORM WARNING/WINTER WEATHER ADVISORY HEADLINES CONTINUE
UNCHANGED. BUMPED SNOW AMOUNTS IN WARNING AREA SLIGHTLY...WITH
LOCALIZED 7-8 INCH NOT OUT OF THE QUESTION THERE.
MID-AFTERNOON FINDS SURFACE LOW PRESSURE OVER THE LOWER OHIO VALLEY
REGION...AND WELL-DEFINED CLOSED LOW ACROSS SOUTHEAST MISSOURI IN
GOES WATER VAPOR IMAGERY. NICE 4-5 MB PRESSURE RISE/FALL COUPLET
ASSOCIATED WITH THE SURFACE LOW...INDICATING SOME DEEPENING STILL
OCCURRING. CLASSIC COMMA SHAPE TO RADAR PRESENTATION IN REGIONAL
MOSAIC...WITH DEFORMATION BAND EXTENDING FROM CENTRAL MISSOURI
ACROSS CENTRAL IL AT 230 PM. PLENTY OF 3/4SM TO 1/4SM VISIBILITY
REPORTS IN MODERATE/HEAVY SNOW WITHIN THIS BAND PER METARS...WITH
HEAVIEST SNOW POISED TO AFFECT WFO CHICAGO WINTER STORM WARNING AREA
VERY SHORTLY. SEVERAL 6-8 INCH SNOWFALL REPORTS HAVE BEEN RECEIVED
FROM UPSTREAM AREAS IN MO/WESTERN IL. A FEW CLOUD-GROUND LIGHTNING
STRIKES CONTINUE TO BE NOTED AHEAD OF THE UPPER LOW...AS NEARBY AS
NORTH OF DECATUR WITHIN THE PAST 30 MINUTES.
OVERALL...LITTLE CHANGE TO FORECAST FROM EARLIER MORNING UPDATE.
SOME TWEAKS MADE WERE TO ADJUST QPF/SNOWFALL AMOUNTS ACROSS THE
ADVISORY/WARNING AREA...BASED ON SEVERAL RECENT MODEL RUNS DEPICTING
UPWARDS OF 0.50 INCHES OF LIQUID EQUIVALENT ACROSS THE SOUTHERN
PORTIONS OF OUR SOUTHERN TIER OF COUNTIES THROUGH THIS EVENING. HAVE
ALSO ADDED A MENTION OF ISOLATED THUNDER ACROSS THIS SAME AREA
THROUGH THE REMAINDER OF THE AFTERNOON HOURS...WITH MODEL DEPICTIONS
OF STEEP MID/UPPER LEVEL LAPSE RATES AND WEAK ELEVATED CAPE AS WELL
AS GRADIENT OF NEGATIVE SATURATED EPV ACROSS THE AREA INTO EARLY
EVENING. HAVE ENDED UP ADDING ABOUT AN INCH OVERALL TO OUR FAR SOUTH
AREA...WHILE DECREASING AMOUNTS FARTHER NORTH AND TRYING TO SHARPEN
UP THE GRADIENT FROM NOT MUCH SNOW TO SIGNIFICANT SNOW SOUTH OF
INTERSTATE 80 CORRIDOR. HEAVIEST SNOW EXPECTED TO OCCUR FROM THE
REMAINDER OF THE AFTERNOON HOURS INTO EARLY EVENING...BEFORE
TAPERING OFF TO LIGHT SNOW BY LATE EVENING/OVERNIGHT.
PERHAPS THE HARDEST PART OF FORECAST IS WITH THE LAKE EFFECT SNOW
POTENTIAL ACROSS NORTHEAST IL/NORTHWEST IND LATER TONIGHT AND
MONDAY. STRONG NORTHEAST WINDS WILL CONTINUE TO PROVIDE MOISTURE
CONVERGENCE AND FLUX OFF OF THE LAKE DURING THE PERIOD...THOUGH
FORECAST SOUNDINGS CONTINUE TO SHOW GENERALLY MARGINAL THERMODYNAMIC
PARAMETERS FOR STRONGER LAKE EFFECT SNOW. DELTA T VALUES GRADUALLY
INCREASE TO ONLY 13/14 DEG C THROUGH MONDAY AFTERNOON...WITH
INVERSION HEIGHTS SLOWLY RISING TO NEAR 7000 FT AGL LATE TONIGHT AND
MONDAY. THIS SHOULD SUPPORT INITIALLY WEAK MULTI-BAND LES INTO
EASTERN WI/NORTHEAST IL...THOUGH ACCUMULATION IS NOT EXPECTED TO BE
OF MUCH SIGNIFICANCE GIVEN WEAK THERMAL PROFILES.
AWAY FROM THE LAKE...STEEP LOW LEVEL LAPSE RATES IN BROAD AREA OF
COOL CYCLONIC FLOW WEST OF DEPARTING STORM WILL LIKELY SUPPORT
SCATTERED FLURRIES AND LIGHT SNOW SHOWERS MONDAY...BUT AGAIN WITH
LITTLE/NO ORGANIZED ACCUMULATION EXPECTED.
BLEND OF MOS TEMPS GENERALLY ACCEPTED TONIGHT/MONDAY...THOUGH WENT A
LITTLE ABOVE GUIDANCE IN A FEW SPOTS TONIGHT WITH PERSISTENT CLOUD
COVER.
RATZER
MEDIUM/LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY...
MONDAY NIGHT THROUGH TUESDAY...LAKE EFFECT SNOW SHOWERS WILL BE THE
MAIN CONCERN THROUGH TUESDAY. THE UPPER LOW WILL BE STEADILY MOVING
EASTWARD INTO THE ATLANTIC BUT A BROAD TROUGH/CYCLONIC FLOW WILL
EXPAND WELL TO THE WEST OF THE MAIN SYSTEM LEAVING THE LOCAL AREA
UNDER A NORTHWEST UPPER FLOW. WEAK UPPER RIDGING WILL BE IN PLACE
OVER THE FAR WESTERN U.S. BUT THIS LOOKS TO BE INTERRUPTED BY ENERGY
TRANSLATING THROUGH IT FROM THE EASTERN PACIFIC. HIGH PRESSURE WILL
BE SPRAWLED ACROSS THE MID SECTION OF NORTH AMERICA WHICH WILL KEEP
NORTHERLY LOW LEVEL FLOW IN PLACE LOCALLY. THIS WILL KEEP AIR
MARGINALLY COLD ENOUGH FOR LAKE EFFECT TO REMAIN IN PLACE MONDAY
NIGHT AND TUESDAY. LAKE TO H85 DELTA T/S GENERALLY RANGE FROM 11 TO
13C DURING THE PERIOD WITH INVERSION HEIGHTS HOVERING AROUND 5000 FT
WITH FLUCTUATIONS ABOVE AND BELOW THAT AT TIMES. THE FETCH REMAINS
FAVORABLE FOR ANY SNOW SHOWERS TO AFFECT FAR EASTERN COOK/WILL AND
LAKE INDIANA AND WESTERN PORTER MONDAY EVENING WITH A SLOW SHIFT
EASTWARD INTO THE OVERNIGHT HOURS. LATE MONDAY EVENING/MONDAY NIGHT
MAY BE THE PEAK TIME FOR LAKE EFFECT SNOW SHOWERS AS INVERSION
HEIGHTS ARE EXPECTED TO RISE TO 6000 OR POSSIBLY NEAR 7000 FT WITH
DELTA T/S AROUND 12C. WILL CARRY HIGHEST CHANCE POPS FOR THIS PERIOD
WITH LAKE COUNTY INDIANA AND PORTER COUNTY THE FOCUS AREAS. ASSUMING
SNOW SHOWERS DO BECOME SOMEWHAT ORGANIZED...SOME LIGHT ACCUMULATION
IS POSSIBLE...PROBABLY ON THE ORDER OF AN INCH OR MAYBE 2 BUT DO NOT
HAVE THE GREATEST CONFIDENCE IN AMOUNTS. WINDS GAIN ENOUGH OF A
WESTERLY COMPONENT TO GRADUALLY SHIFT THE FOCUS EASTWARD THROUGH THE
DAY ON TUESDAY. LAKE PARAMETERS BECOME LESS FAVORABLE THOUGH STILL
MARGINALLY SUPPORTIVE FOR ACTIVITY TUESDAY BUT SURFACE TEMPS WILL
WARM ABOVE FREEZING SO ACCUMULATION WILL BE TOUGH TO COME BY. AT
THIS POINT THE FOCUS WILL LIKELY BE ACROSS PORTER
COUNTY...ESPECIALLY EAST BUT WILL ONLY CARRY MID CHANCE POPS FOR
NOW. IT DOES APPEAR THAT WINDS WILL TURN NORTHWESTERLY ENOUGH TO
THEN PUSH ANY SNOW SHOWERS EAST OF PORTER COUNTY TUESDAY EVENING.
BEYOND THE LAKE EFFECT AREAS...A MIX OF SUN AND CLOUDS IS EXPECTED
TUESDAY WITH SOME EVIDENCE OF A WEAK SHORTWAVE DROPPING ACROSS THE
AREA. HIGHS WILL CONTINUE TO BE CHILLY IN THE UPPER 30S...BUT IF
ENOUGH SUNSHINE CAN PEAK THROUGH A FEW SPOTS COULD SEE 40...MAINLY
IN THE WEST.
WEDNESDAY THROUGH SUNDAY...THE OVERALL PATTERN REALLY WON/T CHANGE
MUCH ACROSS THE MIDWEST WITH NORTHWESTERLY FLOW CONTINUING ALOFT.
RIDGING WILL BUILD ACROSS THE ROCKIES THROUGH LATE WEEK WHICH WILL
HELP PUSH WARMER AIR ALOFT EASTWARD RESULTING IN MODERATING TEMPS
ACROSS THE LOCAL AREA. H85 TEMPS WARM TO AROUND -4C BY LATE THURSDAY
BUT SURFACE HIGH PRESSURE WILL BE RIGHT OVERHEAD. LAKE BREEZE
DEVELOPMENT APPEARS LIKELY WEDNESDAY...AND ESPECIALLY THURSDAY SO
AREAS NEAR THE LAKE WILL BE HELD INTO THE UPPER 30S TO AROUND 40 FOR
HIGH WEDNESDAY AND THURSDAY WHILE THE REST OF THE AREA WARMS TO
AROUND 40 WEDNESDAY AND INTO THE MID 40S...IF NOT A LITTLE
HIGHER...THURSDAY. AREAS WITH THE GREATEST SNOW COVER FROM
TODAY/TONIGHT WILL LIKELY BE ON THE LOWER END OF THOSE RANGES BUT
THIS WILL BECOME MORE CLEAR ONCE EXTENT/AMOUNT OF SNOW COVER IS
KNOWN IN THE MORNING. AT THIS POINT...THE TRACK OF ANY SHORTWAVES
LOOKS TO REMAIN SOUTHWEST OF THE AREA SO DRY WEATHER IS EXPECTED.
RIDGING CONTINUES TO EXPAND EASTWARD THROUGH SATURDAY BRINGING
FURTHER BUT STILL MODEST WARM ADVECTION INTO THE AREA ALOFT SO THE
WARMING TREND WILL LIKELY CONTINUE. H85 TEMPS WILL BE CLOSE TO -2C
SATURDAY AND A SOUTHWESTERLY WIND WILL HAVE SET UP BEHIND HIGH
PRESSURE DEPARTING TO THE SOUTHEAST. THIS MAY PUSH TEMPS AT LEAST
CLOSE TO IF NOT ABOVE NORMAL. A CUTOFF UPPER LOW WILL BE IN PLACE
OFF THE CALIFORNIA COAST BY THIS TIME WITH ANOTHER TROUGH OVER
ALASKA. SHORTWAVE ENERGY LOOKS TO EJECT FROM THE ALASKA TROUGH AND
TRACK SOUTHEAST THROUGH THE CONTINUED NORTHWESTERLY UPPER FLOW AND
AFFECT THE AREA SATURDAY NIGHT OR SUNDAY WITH THE ECMWF AND GFS
ACTUALLY IN VERY GOOD AGREEMENT WITH THIS. DETAILS OF THIS MAY
CHANGE BUT A SYSTEM SUCH AS THIS MAKES SENSE GIVEN THE MORE ACTIVE
FLOW OVER THE PACIFIC AND THE EASTWARD ADVANCEMENT OF THE UPPER
RIDGE PUSHING THE STORM TRACK FURTHER NORTH AND EAST. WILL CARRY
CHANCE POPS FOR SATURDAY NIGHT AND SUNDAY FOR NOW.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* SNOW OVERSPREADING NORTHEASTERN ILLINOIS THIS AFTERNOON...AND
POTENTIAL IMPACTS DUE TO VSBY/ACCUMULATIONS.
* GUSTY NORTHEAST WINDS AROUND 30 KT GRADUALLY BACKING TO NORTH.
* LAKE EFFECT SNOW SHOWERS DEVELOPING THIS EVENING AND OVERNIGHT.
BMD
//DISCUSSION...UPDATED 20Z...
EARLIER BAND OF SNOW MENTIONED OVER NORTH CENTRAL ILLINOIS FELL
APART QUICKER THAN ORIGINALLY ANTICIPATED RESULTING IN SNOW BEING
PUSHED BACK SEVERAL HOURS THIS AFTERNOON IN THE TAFS. ANOTHER
BAND OF SNOW LIFTING NORTH INTO THE I-80 CORRIDOR WILL LIKELY
SUFFER A SIMILAR FATE AS IT PUSHES INTO DRY AIR AND OVERALL
FORCING DIMINISHES. LATEST RAP/HRRR HOURLY GUIDANCE STILL TRY TO
BRING SOME PRECIP INTO THE CHICAGO TERMINALS EARLY THIS
EVENING...WITH HRRR STILL HINTING AT LAKE ENHANCEMENT.
PREVIOUS 18Z DISCUSSION...
TRICKY FORECAST THIS AFTERNOON DEALING WITH WHAT WILL LIKELY BE A
SHARP CUTOFF OF HEAVY SNOW ACCUMULATIONS WHICH ARE EXPECTED TO BE
SOUTH OF INTERSTATE 80 TO A DUSTING OR LESS ACROSS FAR NORTHERN
ILLINOIS. AFTERNOON RADAR IMAGERY SHOWS AN BATCH OF MODERATE SNOW
MOVING INTO NORTH CENTRAL ILLINOIS ON ITS WAY TOWARDS THE CHICAGO
TERMINALS 20-21Z. THIS AREA IS PRODUCING SNOW DROPPING VSBY TO
LESS THAN A MILE CURRENTLY...HOWEVER EXPECT THIS TO STRUGGLE TO
HOLD TOGETHER AS IT LIFTS INTO DRIER AIR AND AS OVERALL FORCING
DIMINISHES OVER NORTHERN ILLINOIS. LATEST SHORT TERM HOURLY
GUIDANCE AS WELL AS NAM AND SEVERAL HI-RES WRF RUNS ARE ALL IN
GOOD AGREEMENT KEEPING HEAVIEST QPF AXIS ALONG AND SOUTH OF
INTERSTATE 80. MANY OF THESE MODELS KEEP ORD/MDW DRY ALTOGETHER
WHILE OTHERS BRING UP A FEW HUNDREDTHS OF LIQUID EQUIVALENT
PRECIP. GIVEN RADAR TRENDS CANT RULE OUT A LIGHT DUSTING OF SNOW
AT THE TERMINALS THIS AFTERNOON...NOR A BRIEF DROP TO IFR
VSBY...HOWEVER THINK THIS TO BE UNLIKELY AS OF TAF ISSUANCE.
BREEZY NORTHWESTERLY WINDS WILL CONTINUE THROUGH THE REST OF THE
DAY INTO TONIGHT...LIKELY PICKING UP TO AROUND 30 KT THIS
AFTERNOON AND TAPERING SLIGHTLY LATE IN THE EVENING.
FOCUS WILL BE ON LAKE ENHANCED OR LAKE EFFECT SNOW THIS EVENING.
WIND TURNS TO NNE AROUND 00Z THIS EVENING WITH SHALLOW LAKE INDUCED
INSTABILITY POTENTIALLY ENHANCING OR DEVELOPING NEW SHOWERS.
EQUILIBRIUM LEVELS ARE MEAGER INITIALLY...BUT GRADUALLY DEEPEN TO
AROUND 070 BY 10Z AS THE WINDS VERY SLOWLY CONTINUE TO BACK TO THE
NORTH. CAN SEE THE LAKE EFFECT SIGNATURE IN SOME OF THE RAW GUIDANCE
OUTPUT INCLUDING THE GFS/ECMWF AND GEM...BUT PINNING DOWN THE
DETAILS IS HARD SINCE NONE OF THE HIGHER RES GUIDANCE SEEMS TO HINT
AT IT...EXCEPT FOR THE HRRR. THERE IS POTENTIAL FOR SOME LIGHT
ACCUMULATIONS AND IF A BAND DOES GET GOING COULDNT RULE OUT A QUICK
INCH IN SOME PLACES...BUT THINK THAT GIVEN THE MARGINAL THERMAL
CONDITIONS THIS MAY AMOUNT TO LITTLE MORE THAN VERY LIGHT SNOW OR
FLURRIES.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* DECREASING CONFIDENCE THAT SNOW WILL IMPACT THE TERMINALS
RESULTING IN REDUCED VSBY OR ANY ACCUMULATION.
* LOW CONFIDENCE IN TIMING/IMPACTS OF LAKE EFFECT SNOW THIS EVENING.
* HIGH CONFIDENCE IN CIG TRENDS.
* HIGH CONFIDENCE IN WIND TRENDS.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY...MVFR CIGS LIKELY. CHANCE OF LAKE EFFECT SNOW SHOWERS.
TUESDAY...MVFR CIGS.
WEDNESDAY...VFR.
THURSDAY AND FRIDAY...VFR.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...MVFR CIGS LIKELY. CHANCE OF LAKE EFFECT SNOW
SHOWERS.
TUESDAY...MVFR CIGS.
WEDNESDAY THROUGH SATURDAY...VFR.
TRS
&&
.MARINE...
153 PM CDT
THE MAIN WEATHER CONCERNS THROUGH THE PERIOD CONTINUE TO FOCUS ON
THE SIGNIFICANT STORM SYSTEM AFFECTING THE LAKE TONIGHT THROUGH
MONDAY. WINDS HAVE BEGAN INCREASING UP TO 25 TO 30 KT OUT OF THE
EAST-NORTHEAST ALREADY IN RESPONSE TO AN AREA OF DEEPENING LOW
PRESSURE MOVING EAST-NORTHEASTWARD ACROSS WESTERN KENTUCKY EARLY
THIS AFTERNOON. THIS LOW WILL CONTINUE ACROSS THE OHIO VALLEY
TONIGHT...THEN MERGE WITH A NEW LOW MOVING UP THE CENTRAL ATLANTIC
COAST LATER MONDAY. IT APPEARS THE WINDS WILL CONTINUE TO INCREASE
OVER THE NEXT SEVERAL HOURS...WITH GALES OF 35 TO 40 KT BECOMING
LIKELY BY LATE AFTERNOON ACROSS THE FAR SOUTHERN END OF LAKE
MICHIGAN. LATE TONIGHT AND INTO MONDAY THE FLOW WILL TURN MORE
NORTHERLY AS THE LOW MOVES ACROSS THE OHIO VALLEY. IT APPEARS SOME
GALES COULD PERSIST INTO THE EARLY MORNING HOURS...BEFORE EASING
SLIGHTLY TO 30 KT. I UPGRADED THE SMALL CRAFT ADVISORY TO A GALE
WARNING FOR THE ILLINOIS AND INDIANA SHORES...AND I INCLUDED THE
OPEN WATERS OF FAR SOUTHERN LAKE MICHIGAN FOR LATE THIS AFTERNOON
THROUGH MONDAY MORNING.
THE LONG NORTHERLY FETCH WILL RESULT IN SOME VERY HIGH WAVES ACROSS
THE SOUTHERN END OF THE LAKE...INCLUDING THE NEAR SHORE WATERS.
THESE LARGE WAVES WILL LIKELY PROLONG HAZARDOUS CONDITIONS FOR SMALL
CRAFT FOR BOTH THE ILLINOIS AND THE INDIANA NEAR SHORE WATERS BEYOND
THE GALE PERIOD. HOWEVER...CONDITIONS WILL BEGIN TO IMPROVE BY MID
WEEK AS A SURFACE RIDGE OF HIGH PRESSURE APPROACHES THE WESTERN
LAKES. THIS WILL LIKELY RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS INTO THE END OF THE WEEK.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ033-ILZ039 UNTIL 7 AM MONDAY.
WINTER WEATHER ADVISORY...ILZ023-ILZ032 UNTIL 7 AM MONDAY.
IN...WINTER WEATHER ADVISORY...INZ010-INZ011 UNTIL 7 AM MONDAY.
WINTER STORM WARNING...INZ019 UNTIL 7 AM MONDAY.
LM...GALE WARNING...LMZ080-LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ876-LMZ878 UNTIL 10 AM MONDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 5 PM SUNDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...10 AM MONDAY TO 7 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
247 PM CDT SUN MAR 24 2013
.DISCUSSION...
1027 AM CDT
FOR MORNING UPDATE...
HAVE MADE A FEW TWEAKS TO GOING FORECAST...LARGELY TO LOWER POPS AND
QPF/SNOWFALL AMOUNTS A BIT ACROSS THE NORTHERN THIRD/HALF OF THE
CWA...AND TO ADD DETAIL OF LULL IN PRECIP DURING THE MORNING ACROSS
THE SOUTHEAST. WARNING/ADVISORY HEADLINES WILL CONTINUE AS IS...
WITH HIGH-RES GUIDANCE STILL IN GOOD AGREEMENT IN DEPICTING THE
POTENTIAL FOR ACCUMULATING SNOW ACROSS THE SOUTHERN COUPLE OF TIERS
OF CWA COUNTIES LATER THIS AFTERNOON/EARLY EVENING.
MORNING UPPER AIR/WATER VAPOR DATA DEPICT STRONG/COMPACT CLOSED
UPPER LOW OVER SOUTHERN MO/NORTHERN ARKANSAS...WITH SURFACE LOW
ALONG THE MISSISSIPPI RIVER SOUTH OF KPAH. A WEAKER LEAD SHORT WAVE
WAS LIFTING NORTHEAST ACROSS IL/IN/WI...WITH AN ATTENDANT REGION OF
MAINLY LIGHT SNOW/FLURRIES...WHILE THE MAIN SHOW OF MODERATE-HEAVY
SNOW AND THUNDERSNOW WAS LOCATED CLOSER TO THE UPPER LOW ACROSS
MO/WESTERN IL. AREA BETWEEN ADVANCING PRECIP FROM UPPER LOW AND
WEAKER LEAD VORT HAD SHOWN A DECREASE IN PRECIP COVERAGE PER
REGIONAL RADAR MOSAIC...SO HAVE ADJUSTED POPS DOWNWARD ACROSS
SOUTHERN COUNTIES WHERE LITTLE/NO ACCUMULATING PRECIP IS EXPECTED
UNTIL MIDDAY AND BEYOND.
GUIDANCE CONTINUES TO DEEPEN UPPER LOW/SURFACE LOW AS IT MOVES EAST
ACROSS THE LOWER OHIO VALLEY THIS AFTERNOON/EARLY THIS EVENING...
WITH TRENDS IN GUIDANCE CONTINUING TO FOCUS PRECIP ALONG FAR
SOUTHERN CWA AND AREAS DOWNSTATE...WHILE DECREASING QPF ACROSS OUR
NORTHERN COUNTIES. THUS HAVE ADJUSTED POPS/QPF DOWN ACROSS THE NORTH
WHILE MAINTAINING THEM SOUTH...AND HAVE EVEN BUMPED THINGS UP A
LITTLE RIGHT ALONG THE LOT/ILX BORDER AREA BASED ON MODEL CONSENSUS
THERE LATER THIS AFTERNOON/EVENING. HAVE ALSO TWEAKED SHORT TERM SKY
COVER A BIT TO ALLOW FOR THE COUPLE BREAKS OF SUN NOTED OUT THE
OFFICE WINDOW THIS MORNING.
RATZER
//PREV DISCUSSION...
329 AM CDT
SHORT TERM...TODAY THROUGH TUESDAY...
THE FORECAST CONCERNS REMAIN ON THE LATE SEASON WINTER STORM
BRINGING AT LEAST MINOR ACCUMULATING SNOW TO A FAIRLY LARGE PART OF
THE FORECAST AREA. WHILE THE MOST SIGNIFICANT ACCUMULATIONS AND
IMPACTS WILL BE DOWNSTATE IL AND IN...SNOWFALL AMOUNTS OF NEAR OR
IN EXCESS OF SIX INCHES ARE EXPECTED SOUTH OF U.S. HIGHWAY 24 IN
THE SOUTHERNMOST CWA COUNTIES. WAS ON THE FENCE WITH A WARNING OR
JUST A HIGHER END ADVISORY...BUT OPTED WARNING WITH CONFIDENCE
INCREASING IN WHERE THE SNOWFALL GRADIENT WILL BE...AS WELL AS FOR
COLLABORATION PURPOSES.
THE EARLY MORNING WATER VAPOR AND INFRARED SATELLITE LOOPS DEPICT
THE BROAD COLD CORE UPPER LOW OVER THE CENTRAL U.S. WITH THE
STRONG DEVELOPING EMBEDDED UPPER LOW QUICKLY ADVANCING ENE OVER
THE OZARKS. THIS IS ON THE LEADING EDGE OF A WELL-DEFINED UPPER
JET. IN ADVANCE OF THIS LOW IS A WEAK SHORTWAVE MOVING NORTHEAST
OVER THE FORECAST AREA EARLY THIS MORNING...HELPING TO BRING
SUBTLE ISENTROPIC ASCENT AND MOISTENING. OVERALL THE FORCING WITH
THIS IS NOT GREAT AND THE MOIST UPGLIDE BECOMES USED MORE SO BY
THE MAIN LOW TO THE SOUTHWEST...SO THE OVERALL PRECIP AREA WITH
THIS IS ANTICIPATED TO DECREASE IN COVERAGE AFTER DAYBREAK. THE
HRRR AND OTHER HIGH RESOLUTION MODELS AGREE WITH SUCH A TREND. ANY
SNOW THROUGH THE MORNING WITH THIS LOOKS TO MAINLY BE LIGHT...AND
THERE COULD BE A LITTLE HELP FROM SEEDER FEEDER PROCESSES AS THERE
ARE PATCHES OF STRATOCU ALREADY IN PLACE. THIS MAINLY ONLY LIGHT
SNOW THROUGH THE MORNING IS WHY THE HEADLINE START TIME REMAINS AT
1 PM.
THE UPPER LOW WILL CLEARLY SWING TO A NEGATIVE TILT THIS
AFTERNOON WITH A CLASSIC SYNOPTIC LOOK IN THE MODELS FOR HEAVY
SNOW ACROSS CENTRAL IL INTO PARTS OF IN...WITH INGREDIENTS OF DEEP
SATURATED ASCENT AND IMPRESSIVE STEEP ELEVATED LAPSE RATES. THE
TREND FROM 24 HOURS AGO HAS BEEN SOUTH WITH THE GUIDANCE IN ALL
THESE ELEMENTS...AND THAT HAS RESULTED IN A TIGHTENING OF THEIR
OUTPUT GRADIENT IN QPF AND SNOWFALL ACROSS THE SOUTHERN FORECAST
AREA...WHICH WAS FOR THE MOST PART ANTICIPATED. SNOWFALL AMOUNTS
FOR NORTH OF I-80 LOOK TO BE FAIRLY LIGHT AND MAYBE EVEN NOTHING
AT ALL...WHILE SOUTH OF I-80 THE SNOWFALL AMOUNTS ARE EXPECTED TO
INCREASE AND THEN RAPIDLY SOUTH OF HIGHWAY 24. EXPECT THAT
SNOWFALL WILL INCREASE IN INTENSITY ACROSS THE AREA BY EARLY
AFTERNOON IN THE SOUTH AND LATE AFTERNOON IN THE CENTRAL CWA AS
MORE SUBSTANTIAL HEIGHT FALLS AND ASSOCIATED ASCENT ENVELOP THE
AREA.
THE LATE AFTERNOON AND EVENING PERIOD IS WHERE MOST OF THE
ACCUMULATION IS ANTICIPATED...NOT ONLY FOR THE HEADLINE AREA BUT
ALSO IN THE MINOR ACCUMULATIONS NORTH OF THERE. ACROSS THE WARNING
AREA...THE ELEVATED THERMAL GRADIENT IS FORECAST TO TIGHTEN AT
THIS TIME IN THE GFS AND EC SOLUTIONS...WITH FRONTOGENETIC FORCING
INDICATED ON CROSS SECTIONS. MIXING RATIOS ON THE ISENTROPIC
LAYERS ARE AROUND 3 G/KG...AND REALIZING A PERIOD OF MORE MODEST
RATES LOOK LIKELY. SEVERAL OF THE CONVECTIVE ALLOWING GUIDANCE
MODELS DO BRING 35 PLUS DBZ EITHER NEAR OR INTO THIS AREA DURING
THIS PERIOD. WHILE IT DOES NOT LAST LONG...IT LOOKS LIKE THAT
SHOULD ENHANCE LOCAL TOTALS. THOUGH IT COULD BE JUST SOUTH OF THE
FORECAST AREA...ALWAYS A POTENTIAL PROBLEM IN THIS PORTION OF SUCH
A STRONGLY FORCED SYSTEM.
BY LATE TONIGHT...THE STRONGEST FORCING AND DEEPEST MOISTURE BEGIN
TO SLIDE EAST. EXPECT A GRADUAL TAPERING FROM SNOW TO SCATTERED
SNOW SHOWERS. NEAR LAKE MI...EVEN AS EARLY AS THIS
EVENING...THERE MAY BE SOME ENHANCEMENT...THOUGH IT IS
ANTICIPATED TO NOT BE ANYTHING OVERLY STRONG DUE TO LIMITED EL
HEIGHTS AND CONVERGENCE. LATER INTO THE NIGHT AND DURING MONDAY
MORNING THE FOCUS IS ANTICIPATED TO IMPROVE AS ARE THE 850MB TO
LAKE SURFACE TEMP DIFFERENCE /AROUND 12C/. SO HAVE BOOSTED POPS
FOR LAKE EFFECT SNOW SHOWERS OR FLURRIES IN CHICAGO DURING THE
MONDAY MORNING PERIOD AND THEN TRANSITIONING INTO NORTHWEST IN AS
THE SYNOPTIC FLOW BACKS SLIGHTLY WITH THE DEPARTING LOW. AMOUNTS
LOOK TO BE LIGHT AT THIS TIME...BUT THE OCCASIONAL LIGHT SNOW OR
FLURRIES MAY LAST OVER A LONG PERIOD EVEN INTO MONDAY NIGHT AND
TUE FOR NORTHWEST IN.
MTF
LONG TERM...WEDNESDAY THROUGH SUNDAY...
A LARGE RIDGE OF HIGH PRESSURE WILL BE OVER THE GREAT LAKES AND
OHIO VALLEY WEDNESDAY AND WILL SLOWLY MOVE EAST THURSDAY AND FRIDAY.
PROGRESSIVE NORTHWEST FLOW REMAINS ALOFT HOWEVER AND THERE ARE
VARIOUS WEAK WAVES PROGGED TO PASS ACROSS THE PLAINS AND INTO THE
OHIO VALLEY FROM MID WEEK INTO THE WEEKEND WITH SOME OF THESE LIKELY
REMAINING SOUTH OF THE AREA OR PERHAPS JUST CLIPPING THE SOUTHERN
CWA. FAIRLY LOW CONFIDENCE REGARDING ANY OF THESE WAVES AS WELL AS
THERE TIMING/LOCATION AND HAVE CONTINUED WITH A DRY FORECAST THROUGH
THE PERIOD.
TEMPERATURES BEGIN A SLOW WARMING TOWARD THE END OF THE WEEK ON THE
BACK SIDE OF THE HIGH. THOUGH THERE ARE SOME COMPLICATING FACTORS.
FIRST IS HOW MUCH SNOW FALLS AND HOW FAST IT MELTS. LATE MARCH
SUNSHINE HAS EASILY BOOSTED TEMPS INTO THE LOWER/MID 40S OVER BARE
GROUND AND THIS IS LIKELY THE STARTING RANGE...ASSUMING SUNSHINE.
BUT WITH THE WEAK GRADIENT AND LIGHT WINDS...EXPECT A LAKE BREEZE
WEDNESDAY...THURSDAY AND PROBABLY FRIDAY...ASSUMING A LACK OF
CLOUDS/PRECIP. AND THESE LAKE BREEZES WILL PROBABLY FORM FAIRLY
EARLY IN THE AFTERNOON...LIMITING HOW MUCH TIME LAKE SHORE AREAS
HAVE TO WARM UP BEFORE FLOW TURNS OF THE VERY CHILLY LAKE. HAVE
STARTED THE TREND FOR COOLER TEMPS NEAR THE LAKE BUT AS THESE TIME
PERIODS APPROACH...ADDITIONAL DETAILS CAN BE ADDED. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* SNOW OVERSPREADING NORTHEASTERN ILLINOIS THIS AFTERNOON...AND
POTENTIAL IMPACTS DUE TO VSBY/ACCUMULATIONS.
* GUSTY NORTHEAST WINDS AROUND 30 KT GRADUALLY BACKING TO NORTH.
* LAKE EFFECT SNOW SHOWERS DEVELOPING THIS EVENING AND OVERNIGHT.
BMD
//DISCUSSION...UPDATED 20Z...
EARLIER BAND OF SNOW MENTIONED OVER NORTH CENTRAL ILLINOIS FELL
APART QUICKER THAN ORIGINALLY ANTICIPATED RESULTING IN SNOW BEING
PUSHED BACK SEVERAL HOURS THIS AFTERNOON IN THE TAFS. ANOTHER
BAND OF SNOW LIFTING NORTH INTO THE I-80 CORRIDOR WILL LIKELY
SUFFER A SIMILAR FATE AS IT PUSHES INTO DRY AIR AND OVERALL
FORCING DIMINISHES. LATEST RAP/HRRR HOURLY GUIDANCE STILL TRY TO
BRING SOME PRECIP INTO THE CHICAGO TERMINALS EARLY THIS
EVENING...WITH HRRR STILL HINTING AT LAKE ENHANCEMENT.
PREVIOUS 18Z DISCUSSION...
TRICKY FORECAST THIS AFTERNOON DEALING WITH WHAT WILL LIKELY BE A
SHARP CUTOFF OF HEAVY SNOW ACCUMULATIONS WHICH ARE EXPECTED TO BE
SOUTH OF INTERSTATE 80 TO A DUSTING OR LESS ACROSS FAR NORTHERN
ILLINOIS. AFTERNOON RADAR IMAGERY SHOWS AN BATCH OF MODERATE SNOW
MOVING INTO NORTH CENTRAL ILLINOIS ON ITS WAY TOWARDS THE CHICAGO
TERMINALS 20-21Z. THIS AREA IS PRODUCING SNOW DROPPING VSBY TO
LESS THAN A MILE CURRENTLY...HOWEVER EXPECT THIS TO STRUGGLE TO
HOLD TOGETHER AS IT LIFTS INTO DRIER AIR AND AS OVERALL FORCING
DIMINISHES OVER NORTHERN ILLINOIS. LATEST SHORT TERM HOURLY
GUIDANCE AS WELL AS NAM AND SEVERAL HI-RES WRF RUNS ARE ALL IN
GOOD AGREEMENT KEEPING HEAVIEST QPF AXIS ALONG AND SOUTH OF
INTERSTATE 80. MANY OF THESE MODELS KEEP ORD/MDW DRY ALTOGETHER
WHILE OTHERS BRING UP A FEW HUNDREDTHS OF LIQUID EQUIVALENT
PRECIP. GIVEN RADAR TRENDS CANT RULE OUT A LIGHT DUSTING OF SNOW
AT THE TERMINALS THIS AFTERNOON...NOR A BRIEF DROP TO IFR
VSBY...HOWEVER THINK THIS TO BE UNLIKELY AS OF TAF ISSUANCE.
BREEZY NORTHWESTERLY WINDS WILL CONTINUE THROUGH THE REST OF THE
DAY INTO TONIGHT...LIKELY PICKING UP TO AROUND 30 KT THIS
AFTERNOON AND TAPERING SLIGHTLY LATE IN THE EVENING.
FOCUS WILL BE ON LAKE ENHANCED OR LAKE EFFECT SNOW THIS EVENING.
WIND TURNS TO NNE AROUND 00Z THIS EVENING WITH SHALLOW LAKE INDUCED
INSTABILITY POTENTIALLY ENHANCING OR DEVELOPING NEW SHOWERS.
EQUILIBRIUM LEVELS ARE MEAGER INITIALLY...BUT GRADUALLY DEEPEN TO
AROUND 070 BY 10Z AS THE WINDS VERY SLOWLY CONTINUE TO BACK TO THE
NORTH. CAN SEE THE LAKE EFFECT SIGNATURE IN SOME OF THE RAW GUIDANCE
OUTPUT INCLUDING THE GFS/ECMWF AND GEM...BUT PINNING DOWN THE
DETAILS IS HARD SINCE NONE OF THE HIGHER RES GUIDANCE SEEMS TO HINT
AT IT...EXCEPT FOR THE HRRR. THERE IS POTENTIAL FOR SOME LIGHT
ACCUMULATIONS AND IF A BAND DOES GET GOING COULDNT RULE OUT A QUICK
INCH IN SOME PLACES...BUT THINK THAT GIVEN THE MARGINAL THERMAL
CONDITIONS THIS MAY AMOUNT TO LITTLE MORE THAN VERY LIGHT SNOW OR
FLURRIES.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* DECREASING CONFIDENCE THAT SNOW WILL IMPACT THE TERMINALS
RESULTING IN REDUCED VSBY OR ANY ACCUMULATION.
* LOW CONFIDENCE IN TIMING/IMPACTS OF LAKE EFFECT SNOW THIS EVENING.
* HIGH CONFIDENCE IN CIG TRENDS.
* HIGH CONFIDENCE IN WIND TRENDS.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY...MVFR CIGS LIKELY. CHANCE OF LAKE EFFECT SNOW SHOWERS.
TUESDAY...MVFR CIGS.
WEDNESDAY...VFR.
THURSDAY AND FRIDAY...VFR.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...MVFR CIGS LIKELY. CHANCE OF LAKE EFFECT SNOW
SHOWERS.
TUESDAY...MVFR CIGS.
WEDNESDAY THROUGH SATURDAY...VFR.
TRS
&&
.MARINE...
153 PM CDT
THE MAIN WEATHER CONCERNS THROUGH THE PERIOD CONTINUE TO FOCUS ON
THE SIGNIFICANT STORM SYSTEM AFFECTING THE LAKE TONIGHT THROUGH
MONDAY. WINDS HAVE BEGAN INCREASING UP TO 25 TO 30 KT OUT OF THE
EAST-NORTHEAST ALREADY IN RESPONSE TO AN AREA OF DEEPENING LOW
PRESSURE MOVING EAST-NORTHEASTWARD ACROSS WESTERN KENTUCKY EARLY
THIS AFTERNOON. THIS LOW WILL CONTINUE ACROSS THE OHIO VALLEY
TONIGHT...THEN MERGE WITH A NEW LOW MOVING UP THE CENTRAL ATLANTIC
COAST LATER MONDAY. IT APPEARS THE WINDS WILL CONTINUE TO INCREASE
OVER THE NEXT SEVERAL HOURS...WITH GALES OF 35 TO 40 KT BECOMING
LIKELY BY LATE AFTERNOON ACROSS THE FAR SOUTHERN END OF LAKE
MICHIGAN. LATE TONIGHT AND INTO MONDAY THE FLOW WILL TURN MORE
NORTHERLY AS THE LOW MOVES ACROSS THE OHIO VALLEY. IT APPEARS SOME
GALES COULD PERSIST INTO THE EARLY MORNING HOURS...BEFORE EASING
SLIGHTLY TO 30 KT. I UPGRADED THE SMALL CRAFT ADVISORY TO A GALE
WARNING FOR THE ILLINOIS AND INDIANA SHORES...AND I INCLUDED THE
OPEN WATERS OF FAR SOUTHERN LAKE MICHIGAN FOR LATE THIS AFTERNOON
THROUGH MONDAY MORNING.
THE LONG NORTHERLY FETCH WILL RESULT IN SOME VERY HIGH WAVES ACROSS
THE SOUTHERN END OF THE LAKE...INCLUDING THE NEAR SHORE WATERS.
THESE LARGE WAVES WILL LIKELY PROLONG HAZARDOUS CONDITIONS FOR SMALL
CRAFT FOR BOTH THE ILLINOIS AND THE INDIANA NEAR SHORE WATERS BEYOND
THE GALE PERIOD. HOWEVER...CONDITIONS WILL BEGIN TO IMPROVE BY MID
WEEK AS A SURFACE RIDGE OF HIGH PRESSURE APPROACHES THE WESTERN
LAKES. THIS WILL LIKELY RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS INTO THE END OF THE WEEK.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ033-ILZ039 UNTIL 7 AM MONDAY.
WINTER WEATHER ADVISORY...ILZ023-ILZ032 UNTIL 7 AM MONDAY.
IN...WINTER WEATHER ADVISORY...INZ010-INZ011 UNTIL 7 AM MONDAY.
WINTER STORM WARNING...INZ019 UNTIL 7 AM MONDAY.
LM...GALE WARNING...LMZ080-LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ876-LMZ878 UNTIL 4 AM MONDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 5 PM SUNDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...4 AM MONDAY TO 7 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
337 PM EDT SUN MAR 24 2013
.SHORT TERM...
TONIGHT...MONDAY...MONDAY NIGHT...
LATEST WATER VAPOR IMAGERY SHOWING POTENT UPPER TROUGH AND
ASSOCIATED VORT MAX PUSHING ACROSS MISSOURI THIS AFTERNOON. LOW-MID
LEVEL ASCENT AHEAD OF THIS FEATURE IS RESULTING IN A LARGE SWATH OF
HEAVY SNOW OVER EASTERN MO AND WEST CENTRAL IL. RADAR IMAGERY
DEPICTING CONVECTIVE ELEMENTS EMBEDDED WITHIN THIS SNOW BAND WHICH
MAY ACT TO HINDER MOISTURE TRANSPORT NORTHWARD INTO OUR AREA AS THIS
SYSTEM CONTINUES TO MOVE E/NE THIS EVENING. 12Z RAOBS CONFIRMING
LATEST RAP ANALYSIS SHOWING STRONG UPPER JET TRAVERSING THROUGH THE
BASE OF THIS TROUGH...ASSOCIATED UPPER LEVEL DIVERGENCE EXPECTED TO
AID IN THE CONTINUATION OF HEAVY SNOW BAND AS IT MOVES INTO
CENTRAL/NORTHERN INDIANA TONIGHT. MODELS IN DECENT AGREEMENT IN NE
TRACK OF SFC LOW...BRINGING IT INTO NORTHERN KY BY 00Z MON AND UP
INTO SW OH BY 12Z MON...PLACING OUR SOUTHERN CWA IN FAVORABLE AREA
FOR FOR HEAVY SNOW. KEY COMPONENT IN THE EVOLUTION OF THIS SYSTEM
THAT WILL ACT TO LIMIT SNOW ACCUMULATIONS IS THE EASTWARD
PROGRESSION OF UPPER JET DYNAMICS AND THE RESULTING COASTAL TRANSFER
OF ENERGY. THIS WILL RAPIDLY DISSIPATE OH VALLEY SFC LOW MONDAY IN
FAVOR OF INTENSIFICATION OF COASTAL LOW AS CLOSED UPPER LOW
CONTINUES ON EASTWARD TRACK AND BECOMES NEARLY VERTICALLY STACKED
WITH SFC LOW OVER OH VALLEY 09-12Z MON. THAT SAID...THERE STILL
EXISTS A 12 HOUR WINDOW...00Z-12Z MON...OF FAVORABLE CONDITIONS FOR
ACCUMULATING SNOW AS ALL MODELS IN GOOD AGREEMENT WITH PRODUCING 6-8
INCHES OVER THE FAR SOUTHERN PORTION OF THE CWA AS 80-100M 500MB HT
FALLS WILL REACH UP INTO THE SOUTHERN CWA AS UPPER LOW TRACKS
THROUGH KY OVERNIGHT. AND WHILE MODELS VARY ON DEGREE OF DEEP
MOISTURE AVAILABLE...AMPLE LOW LEVEL MOISTURE ALONG WITH BETTER
ALIGNMENT OF OMEGA AND DGZ THAN PREVIOUS RUNS WILL ALSO FAVOR A GOOD
SHOT AT HVY SNOW FOR AT LEAST A BRIEF PERIOD OF TIME OVERNIGHT
ACROSS THE SOUTHERN TIER OF THE FCST AREA. WILL THEREFORE CONTINUE
WITH WARNING/ADV AREAS AND KEEP NORTHERN TIER WITHOUT HEADLINES AS
DISTINCT CUTOFF IN SNOW EXPECTED NORTH OF US6. IN THE WAKE OF THIS
SYSTEM FLOW WILL GRADUALLY BACK FROM NE TO N/NW LATE IN THE DAY
MONDAY AND BRING CHANCE FOR LES INTO OUR EXTREME NW CWA. DESPITE
UNIFORM NORTHERLY FLOW DOWN THE LONG AXIS OF LAKE MICHIGAN...LACK OF
COLD AIR WILL YIELD MARGINAL/SUB MARGINAL DELTA T AND THEREFORE
HINDER ACCUMULATIONS.
&&
.LONG TERM...
TUESDAY THROUGH SUNDAY...INCREASED SNOW CHANCES TUESDAY AND TUESDAY
NIGHT OVER AREAS DOWNSTREAM OF LAKE MICHIGAN AS VERY COLD AIR
CONTINUES TO SPREAD SOUTH OVER THE WESTERN GREAT LAKES REGION. DELTA
T VALUES RATHER MODEST AT 12C TO 14C...BUT A LONG LAKE AXIS FETCH
WITH LIKELY PRECONDITIONING FROM LAKE SUPERIOR SHOULD ALLOW FOR SOME
ORGANIZATION OF SNOW SHOWERS OVER THE LAKE. RAISED SNOWFALL AMOUNTS
TUESDAY...HOWEVER...DAYTIME HEATING SHOULD LIMIT SNOW ACCUMULATIONS.
INVERSIONS HEIGHTS SHOULD FALL LATE TUESDAY NIGHT...BRINGING AN END
TO THE SNOW SHOWERS. HIGH AND LOW FCST TEMPERATURES ARE CHALLENGING
EARLY IN THE PERIOD GIVEN LOCATIONS AND AMOUNTS OF LINGERING SNOW
COVER AND A GRADUALLY MODIFYING AIRMASS. ANTICIPATED SOME SNOW COVER
SHOULD BE REMAINING OVER THE SOUTHERN THIRD OF THE AREA...SO HAVE
MADE SOME TEMPERATURE MODIFICATIONS TO THESE AREAS. OTHERWISE...
TEMPERATURES SHOULD STILL STRUGGLE TO GET BACK TO NORMAL. PREFERRED
THE COLDER GFS MEAN MOS TEMPERATURES THAT SEEM TO TAKE INTO ACCOUNT
A CHILLY MODIFYING AIRMASS. THE ECMWF IS EVEN COLDER THAN THE
GFS...WITH 850 MB TEMPS STAYING BELOW 0C EXCEPT FOR LATE SUNDAY.
&&
.AVIATION... / 18Z TAFS/
INITIAL WAVE HAS DEPARTED EAST OF OUR AREA WHICH WILL KEEP
CONDITIONS DRY THROUGH THE REMAINDER OF THE AFTERNOON. THE ONLY
EXCEPTION IS AT KFWA WHERE A FEW HEAVIER SNOW SHOWERS MAY MOVE
THROUGH OVER THE NEXT FEW HOURS. AFTER THAT...THE MAIN WAVE WILL
REACH THE AREA DURING THE EVENING HOURS WITH THE HEAVIEST SNOWFALL
ARRIVING BETWEEN 10PM AND MIDNIGHT. HEAVIEST SNOWFALL ANTICIPATED
AT KFWA...CLOSER TO THE SURFACE LOW...WHILE KSBN WILL BE ON THE
NORTHERN FRINGE OF THE PRECIPITATION SHIELD. ANTICIPATE SNOWFALL
TO TAPER OFF FROM NORTHWEST TO SOUTHEAST DURING THE MORNING HOURS
AS THE LOW PRESSURE SYSTEM DEPARTS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 10 AM EDT /9 AM CDT/ MONDAY FOR
INZ008-009-012>018.
WINTER STORM WARNING UNTIL 10 AM EDT MONDAY FOR INZ020-022>027-
032>034.
MI...NONE.
OH...WINTER WEATHER ADVISORY UNTIL 2 PM EDT MONDAY FOR OHZ004-005-015-
016.
WINTER STORM WARNING UNTIL 2 PM EDT MONDAY FOR OHZ024-025.
LM...SMALL CRAFT ADVISORY UNTIL 5 AM EDT TUESDAY FOR LMZ043-046.
&&
$$
SHORT TERM...JAL
LONG TERM...SKIPPER
AVIATION...JAL
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
251 PM EDT SUN MAR 24 2013
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 322 AM EDT SUN MAR 24 2013
A STRENGTHENING LOW PRESSURE SYSTEM WILL LIFT NORTHEAST ACROSS
EASTERN KENTUCKY TODAY AND THIS EVENING BEFORE MOVING INTO SOUTHERN
OHIO OVERNIGHT. THIS SYSTEM IS EXPECTED TO BRING SIGNIFICANT WET
SNOW ACCUMULATION TO CENTRAL INDIANA ESPECIALLY CONSIDERING IT IS
LATE MARCH. SNOW ACCUMULATION WILL BE HEAVIEST LATE THIS AFTERNOON
AND TONIGHT. SCATTERED SNOW SHOWERS WILL LINGER BEFORE HIGH PRESSURE
GRADUALLY BUILDS IN FROM THE PLAINS BRINGING DRY WEATHER AND
GRADUALLY WARMING TEMPERATURES THROUGH LATE WEEK. BY
SATURDAY...HIGHS COULD BE NEAR NORMAL MOSTLY IN THE 50S WITH RAIN
SHOWER CHANCES IN SOUTHERLY FLOW ON THE BACK SIDE OF HIGH PRESSURE.
&&
.NEAR TERM /REST OF TODAY AND TONIGHT/...
ISSUED AT 1026 AM EDT SUN MAR 24 2013
AT 10 AM LOW PRESSURE OF JUST UNDER 1000 MB WAS CENTERED NEAR THE
MISSOURI BOOT HEEL. RADAR SHOWS MOST SNOWFALL HAS ENDED MOMENTARILY
ACROSS CENTRAL INDIANA WITH MODERATE TO HEAVY SNOW ACROSS WESTERN
AND SOUTHERN ILLINOIS AND RAIN SOUTH OF THERE. SLEET HAS ALSO BEEN
REPORTED WITHIN THE PAST COUPLE HOURS. TEMPERATURES IN THE AREA
RANGE FROM THE UPPER 20S IN THE NORTHEAST TO THE MIDDLE 30S ACROSS
THE SOUTH.
FOR THE UPDATE LEANED HEAVILY ON HRRR FOR TIMING OF RETURN OF
PRECIP BUT SPED UP BY A COUPLE HOURS BASED ON COMPARISON WITH
CURRENT RADAR ECHOES. WITH TRACK OF 6Z NAM JUMPING NORTH AND RAP
OVERDOING WARM INTRUSION COMPARED TO OBSERVATIONS USED SREFS AND
GFS FORECAST SOUNDINGS FOR PRECIP TYPE. ADDED SOME TIMING TO THE
POPS FOR THE REST OF THE DAY TO INDICATE A LULL IN ACTIVITY DURING
THE MORNING WITH POPS RAPIDLY INCREASING FROM THE WEST IN THE 11
AM TO NOON TIME FRAME AND OVERSPREADING THE AREA FROM THERE.
FORECAST SOUNDINGS INDICATE SOME POTENTIAL FOR SLEET TO MIX IN AS
FAR NORTH AS THE I-70 CORRIDOR SO ADDED A CHANCE FOR SLEET THERE
THROUGH MUCH OF THE AFTERNOON. MAINTAINED A MIX OF RAIN AND SNOW
IN THE SOUTH WITH THE AFOREMENTIONED SLEET POTENTIAL. SOUNDINGS
INDICATE A CHANGEOVER TO ALL SNOW BY AROUND 22-23Z. SOME CONCERN
THAT MIX OF RAIN AND SLEET WITH THE SNOW COULD DROP SNOWFALL
ACCUMULATION IN THE SOUTH DURING THE TODAY PERIOD BY A DECENT
AMOUNT...BUT THIS IS COUNTERACTED BY SIGNIFICANT SNOWFALL RATES
UPSTREAM IN SOUTHWESTERN AND CENTRAL ILLINOIS OF 1-3 INCHES PER
HOUR AND THUS MAKING NO APPRECIABLE CHANGES TO SNOWFALL AMOUNTS AT
THIS TIME. WITH OBSERVATIONS OF A FEW LIGHTNING STRIKES UPSTREAM
AND SYSTEM ONLY PROGGED TO STRENGTHEN AS IT ARRIVES ADDED A
SLIGHT CHANCE FOR THUNDER SOUTH OF INTERSTATE 70 AS WELL.
PREVIOUS DISCUSSION FOLLOWS...
MAIN CHALLENGE TODAY WILL BE PRECIPITATION TIMING AND TYPE
ALONG WITH SNOW AMOUNTS AS MODELS ARE NOW COMING TOGETHER NICELY
IN HANDLING THE STRENGTH AND LOCATION OF LOW PRESSURE SYSTEM THAT
IS PROGGED TO LIFT NORTHEAST FROM THE SOUTHERN STATES TO EAST
CENTRAL KENTUCKY BY 00Z MONDAY. STRONG UPPER LOW MOVING TO NEAR THE
CONFLUENCE OF THE OHIO AND MISSISSIPPI RIVERS ALONG WITH A VIGOROUS
140 PLUS KNOT JET ACROSS THE TENNESSEE VALLEY WILL RESULT IN THE
AFOREMENTIONED SURFACE LOW DEEPENING TO LESS THAN 995 MILLIBARS BY
EVENING AND RESULT IN MODERATE TO HEAVY SNOW BY LATE AFTERNOON.
WITH MODELS TRENDING A LITTLE BIT FURTHER SOUTH THAN PREVIOUS
RUNS...HEAVIEST SNOW TODAY SHOULD BE ALONG AND SOUTH OF INTERSTATE
70 AND TO THE NORTH OF THE MIXED AREA. THIS AREA WILL ALSO BE NEAR
ELONGATED 850 MILLIBAR FRONTOGENESIS AND INSTABILITY ALOFT THAT
COULD AID IN SNOW AMOUNTS...ALTHOUGH SNOW RATIOS WILL BE ON THE LOW
SIDE UNTIL LATE IN THE DAY WHEN THE COLUMN COOLS FURTHER AS THE LOW
MOVES INTO SOUTHERN OHIO. AT THIS POINT...STRONG DYNAMICS INCLUDING
QVECTOR CONVERGENCE FROM 850-500 MILLIBARS ALONG WITH
FRONTOGENETICAL FORCING...DIFFLUENT FLOW ALOFT AND INSTABILITY
ALOFT SHOULD RESULT IN MODERATE TO HEAVY SNOW WITH BANDING PRODUCING
THE HIGHEST AMOUNTS.
SNOWFALL AMOUNTS WILL CONTINUE TO BE TRICKY...WITH THE GROUND AND
SURFACE TEMPERATURES STARTING OFF ABOVE FREEZING WHICH SHOULD LOWER
SNOW AMOUNTS FROM WHAT EARLIER MODEL RUNS HAD...UPWARDS OF 12 INCHES
IN THE HEAVIEST SNOW BAND. BUFKIT SUGGESTS THIS SCENARIO ALONG WITH
DECENT COMPACTION OF THE SNOW. ALSO...EXACT AREA OF PROLONGED
BANDING STILL UP IN THE AIR...HOWEVER A WIDESPREAD 6 INCH STORM
TOTAL SNOW AMOUNT LOOKS GOOD THROUGH MONDAY MORNING WITH 10 INCH
AMOUNTS AND LOCALLY HIGHER NEAR THE DEFORMATION ZONE WHICH SHOULD BE
FAIRLY CLOSE TO EITHER SIDE OF THE INTERSTATE 70 CORRIDOR AND A BIT
FURTHER NORTH OF THE LATE AFTERNOON HEAVY SNOW. WITH MODEL LOW
TRACKS AND RESULTANT SNOWFALL ACCUMULATION A LITTLE FURTHER
SOUTH...WILL UPGRADE THE SOUTHERNMOST TIER TO A WINTER STORM WARNING
AND KEEP THE WARNING GOING ELSEWHERE THROUGH NOON EDT MONDAY.
POPS WILL INCREASE TO OCCASIONAL FROM SOUTHWEST TO NORTHEAST TODAY
WITH MOST OR ALL OF CENTRAL INDIANA SEEING PRECIPITATION BY 18Z.
POPS WILL ONLY DROP SLIGHTLY TO LIKELY TOWARD MORNING.
COULD ALSO SEE SOME BLOWING SNOW TODAY AS BUFKIT SUGGESTS GUSTS TO
30 MPH OR MORE.
WITH THICK CLOUDS AROUND TODAY ALONG WITH EVAPORATIVE
COOLING...COLDER NAM MOS AND ALLBLEND TEMPERATURES IN THE
LOWER 30S NORTH TO THE MID 30S SOUTH LOOK GOOD.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 322 AM EDT SUN MAR 24 2013
MODELS AGREE THAT THROUGH THEIR QPF FIELDS THAT THE SNOW WILL BE
WINDING DOWN ON MONDAY WITH ONLY LINGERING SMALL SNOW SHOWER CHANCES
THROUGH TUESDAY. FINALLY...COULD SEE SOME CLEARING AND THE COLDEST
TEMPERATURES OF THE WEEK TUESDAY NIGHT WITH THE SNOW PACK SERVING TO
MAXIMIZE RADIATIONAL HEAT LOSS TO SPACE.
AFTERNOON TEMPERATURES WILL BE WELL BELOW NORMAL WITH THE
SNOW...NORTHWEST WINDS AND CLOUD COVER.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 251 PM EDT SUN MAR 24 2013
AFTER THE BUSY WEATHER EXPECTED OVER THE NEXT 24 HOURS...THE
EXTENDED PERIOD LOOKS MUCH QUIETER. OHIO VALLEY WILL STILL BE IN
COLD CYCLONIC FLOW IN THE WAKE OF THE STRONG STORM...BUT HIGH
PRESSURE WILL BE BUILDING IN WITH DRY WEATHER FOR MUCH OF THE
SECOND HALF OF THE WEEK. UPPER FLOW PATTERN WILL GRADUALLY
TRANSITION TO NORTHWEST FLOW ALOFT WITH TEMPS GRADUALLY WARMING
THROUGH THE END OF THE WEEK. A WEAK DISTURBANCE ALOFT WILL PASS
THROUGH THE LOWER OHIO VALLEY FRIDAY AND FRIDAY NIGHT WITH A SMALL
CHANCE FOR RAIN SHOWERS. A MUCH BETTER CHANCE FOR RAIN TO COME
SUNDAY AS A COLD FRONT MOVES ACROSS THE REGION.
UNDERCUT LOW TEMPS FROM MOS GUIDANCE BOTH TUESDAY/WEDNESDAY NIGHTS
WITH LIKELIHOOD OF RESIDUAL SNOW COVER. HIGHS WILL GRADUALLY WARM
BACK INTO THE 50S BY THE WEEKEND AND ALLBLEND CAPTURED THIS IDEA
WELL.
&&
.AVIATION /DISCUSSION FOR 241800Z TAF ISSUANCE/...
ISSUED AT 126 PM EDT SUN MAR 24 2013
CONDITIONS WILL RAPIDLY DETERIORATE LATE THIS AFTERNOON TO VLIFR
WITHIN HEAVY SNOW. IFR AND LOWER CONDITIONS WILL PERSIST INTO
MONDAY AFTERNOON.
CENTRAL INDIANA REMAINS WITHIN A DRY SLOT IN THE WAKE OF THE
MORNING SNOW. THE CALM BEFORE THE STORM IF YOU WILL AS HEAVY
PRECIP MOVING EAST ACROSS ILLINOIS AHEAD OF A DEEPENING LOW
PRESSURE. LOW LEVEL THERMAL ANALYSIS STILL SHOWING A WARM PUNCH
ALOFT MOVING ACROSS THE SOUTHERN HALF OF THE FORECAST AREA OVER
THE NEXT 3-4 HOURS BEFORE 850MB TEMPS CRASH. THIS IS LIKELY TO
ENABLE A PERIOD OF MIXING WITH RAIN...SLEET AND SNOW AT KBMG
BEGINNING AROUND OR SHORTLY AFTER 20Z. MAY EVEN SEE A BIT OF SLEET
MIX AT KIND IN THE 20-21Z TIME PERIOD. ANY MIXING WILL BE SHORT-
LIVED HOWEVER AS EVAPORATIVE COOLING TAKES PLACE THROUGH THE
BOUNDARY LAYER...WITH PRECIP CHANGING TO ALL SNOW AT BOTH KIND AND
KBMG AFTER 21Z.
SNOW WILL BECOME HEAVY BY EARLY EVENING AT ALL TERMINALS AS AXIS
OF DEEPEST FORCING WITH A STRONG WELL DEVELOPED TROWAL SETS UP IN
THE VICINITY OF THE I-70 CORRIDOR. CONSIDERING REPORTS TO THE WEST
OVER MISSOURI AND ILLINOIS AND THE ANTICIPATION THAT THE LOW
STRENGTHENS FURTHER AS IT MOVES INTO THE REGION THIS EVENING...
EXPECT A 3-6 HOUR PERIOD OF VERY HEAVY SNOWFALL WITH VISIBILITIES
AT OR UNDER 1/4SM. CONVECTIVE POTENTIAL AS WELL THROUGH THE
EVENING...ENHANCING SNOWFALL RATES WITHIN ANY THUNDERSNOW. HAVE
LEFT OUT ANY CB MENTION AT THIS TIME...BUT GREATEST POTENTIAL FOR
THUNDERSNOW WILL BE WITHIN THE HEAVIEST SNOWFALL DURING THE
EVENING.
HEAVIEST SNOW WILL SHIFT NORTH OF I-70 BEFORE SLIDING BACK TO THE
SOUTH/EAST IN THE 06-12Z TIME PERIOD. WHILE 1/4SM HEAVY SNOW MAY
CONTINUE THROUGH THIS TIME...FORCING ALOFT IS GRADUALLY WEAKENING
WITH THE STORM SHIFTING TO THE EAST. WILL CARRY 1/2SM AND MODERATE
SNOW THROUGH THE PERIOD AND LET LATER SHIFTS DETERMINE ADDITIONAL
CHANGES AS CONDITIONS EVOLVE OVERNIGHT. SNOW WILL DIMINISH IN
COVERAGE AND INTENSITY FROM NORTHWEST TO SOUTHEAST THROUGH EARLY
MONDAY AFTERNOON...BUT REMAIN ACROSS THE REGION THROUGHOUT THE
DAY. MAINTAIN IFR CONDITIONS THROUGH 18Z MONDAY. NORTHEAST WINDS
THIS AFTERNOON WILL BACK TO NORTHERLY THIS EVENING...THEN N/NW LATE
TONIGHT INTO MONDAY. GUSTS AT 25 TO 30KTS ARE POSSIBLE THROUGHOUT
THE PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL NOON EDT MONDAY FOR INZ021-028>031-
035>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...MK
NEAR TERM...CP
SHORT TERM...MK
LONG TERM....RYAN
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
126 PM EDT SUN MAR 24 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 322 AM EDT SUN MAR 24 2013
A STRENGTHENING LOW PRESSURE SYSTEM WILL LIFT NORTHEAST ACROSS
EASTERN KENTUCKY TODAY AND THIS EVENING BEFORE MOVING INTO SOUTHERN
OHIO OVERNIGHT. THIS SYSTEM IS EXPECTED TO BRING SIGNIFICANT WET
SNOW ACCUMULATION TO CENTRAL INDIANA ESPECIALLY CONSIDERING IT IS
LATE MARCH. SNOW ACCUMULATION WILL BE HEAVIEST LATE THIS AFTERNOON
AND TONIGHT. SCATTERED SNOW SHOWERS WILL LINGER BEFORE HIGH PRESSURE
GRADUALLY BUILDS IN FROM THE PLAINS BRINGING DRY WEATHER AND
GRADUALLY WARMING TEMPERATURES THROUGH LATE WEEK. BY
SATURDAY...HIGHS COULD BE NEAR NORMAL MOSTLY IN THE 50S WITH RAIN
SHOWER CHANCES IN SOUTHERLY FLOW ON THE BACK SIDE OF HIGH PRESSURE.
&&
.NEAR TERM /REST OF TODAY AND TONIGHT/...
ISSUED AT 1026 AM EDT SUN MAR 24 2013
AT 10 AM LOW PRESSURE OF JUST UNDER 1000 MB WAS CENTERED NEAR THE
MISSOURI BOOT HEEL. RADAR SHOWS MOST SNOWFALL HAS ENDED MOMENTARILY
ACROSS CENTRAL INDIANA WITH MODERATE TO HEAVY SNOW ACROSS WESTERN
AND SOUTHERN ILLINOIS AND RAIN SOUTH OF THERE. SLEET HAS ALSO BEEN
REPORTED WITHIN THE PAST COUPLE HOURS. TEMPERATURES IN THE AREA
RANGE FROM THE UPPER 20S IN THE NORTHEAST TO THE MIDDLE 30S ACROSS
THE SOUTH.
FOR THE UPDATE LEANED HEAVILY ON HRRR FOR TIMING OF RETURN OF
PRECIP BUT SPED UP BY A COUPLE HOURS BASED ON COMPARISON WITH
CURRENT RADAR ECHOES. WITH TRACK OF 6Z NAM JUMPING NORTH AND RAP
OVERDOING WARM INTRUSION COMPARED TO OBSERVATIONS USED SREFS AND
GFS FORECAST SOUNDINGS FOR PRECIP TYPE. ADDED SOME TIMING TO THE
POPS FOR THE REST OF THE DAY TO INDICATE A LULL IN ACTIVITY DURING
THE MORNING WITH POPS RAPIDLY INCREASING FROM THE WEST IN THE 11
AM TO NOON TIME FRAME AND OVERSPREADING THE AREA FROM THERE.
FORECAST SOUNDINGS INDICATE SOME POTENTIAL FOR SLEET TO MIX IN AS
FAR NORTH AS THE I-70 CORRIDOR SO ADDED A CHANCE FOR SLEET THERE
THROUGH MUCH OF THE AFTERNOON. MAINTAINED A MIX OF RAIN AND SNOW
IN THE SOUTH WITH THE AFOREMENTIONED SLEET POTENTIAL. SOUNDINGS
INDICATE A CHANGEOVER TO ALL SNOW BY AROUND 22-23Z. SOME CONCERN
THAT MIX OF RAIN AND SLEET WITH THE SNOW COULD DROP SNOWFALL
ACCUMULATION IN THE SOUTH DURING THE TODAY PERIOD BY A DECENT
AMOUNT...BUT THIS IS COUNTERACTED BY SIGNIFICANT SNOWFALL RATES
UPSTREAM IN SOUTHWESTERN AND CENTRAL ILLINOIS OF 1-3 INCHES PER
HOUR AND THUS MAKING NO APPRECIABLE CHANGES TO SNOWFALL AMOUNTS AT
THIS TIME. WITH OBSERVATIONS OF A FEW LIGHTNING STRIKES UPSTREAM
AND SYSTEM ONLY PROGGED TO STRENGTHEN AS IT ARRIVES ADDED A
SLIGHT CHANCE FOR THUNDER SOUTH OF INTERSTATE 70 AS WELL.
PREVIOUS DISCUSSION FOLLOWS...
MAIN CHALLENGE TODAY WILL BE PRECIPITATION TIMING AND TYPE
ALONG WITH SNOW AMOUNTS AS MODELS ARE NOW COMING TOGETHER NICELY
IN HANDLING THE STRENGTH AND LOCATION OF LOW PRESSURE SYSTEM THAT
IS PROGGED TO LIFT NORTHEAST FROM THE SOUTHERN STATES TO EAST
CENTRAL KENTUCKY BY 00Z MONDAY. STRONG UPPER LOW MOVING TO NEAR THE
CONFLUENCE OF THE OHIO AND MISSISSIPPI RIVERS ALONG WITH A VIGOROUS
140 PLUS KNOT JET ACROSS THE TENNESSEE VALLEY WILL RESULT IN THE
AFOREMENTIONED SURFACE LOW DEEPENING TO LESS THAN 995 MILLIBARS BY
EVENING AND RESULT IN MODERATE TO HEAVY SNOW BY LATE AFTERNOON.
WITH MODELS TRENDING A LITTLE BIT FURTHER SOUTH THAN PREVIOUS
RUNS...HEAVIEST SNOW TODAY SHOULD BE ALONG AND SOUTH OF INTERSTATE
70 AND TO THE NORTH OF THE MIXED AREA. THIS AREA WILL ALSO BE NEAR
ELONGATED 850 MILLIBAR FRONTOGENESIS AND INSTABILITY ALOFT THAT
COULD AID IN SNOW AMOUNTS...ALTHOUGH SNOW RATIOS WILL BE ON THE LOW
SIDE UNTIL LATE IN THE DAY WHEN THE COLUMN COOLS FURTHER AS THE LOW
MOVES INTO SOUTHERN OHIO. AT THIS POINT...STRONG DYNAMICS INCLUDING
QVECTOR CONVERGENCE FROM 850-500 MILLIBARS ALONG WITH
FRONTOGENETICAL FORCING...DIFFLUENT FLOW ALOFT AND INSTABILITY
ALOFT SHOULD RESULT IN MODERATE TO HEAVY SNOW WITH BANDING PRODUCING
THE HIGHEST AMOUNTS.
SNOWFALL AMOUNTS WILL CONTINUE TO BE TRICKY...WITH THE GROUND AND
SURFACE TEMPERATURES STARTING OFF ABOVE FREEZING WHICH SHOULD LOWER
SNOW AMOUNTS FROM WHAT EARLIER MODEL RUNS HAD...UPWARDS OF 12 INCHES
IN THE HEAVIEST SNOW BAND. BUFKIT SUGGESTS THIS SCENARIO ALONG WITH
DECENT COMPACTION OF THE SNOW. ALSO...EXACT AREA OF PROLONGED
BANDING STILL UP IN THE AIR...HOWEVER A WIDESPREAD 6 INCH STORM
TOTAL SNOW AMOUNT LOOKS GOOD THROUGH MONDAY MORNING WITH 10 INCH
AMOUNTS AND LOCALLY HIGHER NEAR THE DEFORMATION ZONE WHICH SHOULD BE
FAIRLY CLOSE TO EITHER SIDE OF THE INTERSTATE 70 CORRIDOR AND A BIT
FURTHER NORTH OF THE LATE AFTERNOON HEAVY SNOW. WITH MODEL LOW
TRACKS AND RESULTANT SNOWFALL ACCUMULATION A LITTLE FURTHER
SOUTH...WILL UPGRADE THE SOUTHERNMOST TIER TO A WINTER STORM WARNING
AND KEEP THE WARNING GOING ELSEWHERE THROUGH NOON EDT MONDAY.
POPS WILL INCREASE TO OCCASIONAL FROM SOUTHWEST TO NORTHEAST TODAY
WITH MOST OR ALL OF CENTRAL INDIANA SEEING PRECIPITATION BY 18Z.
POPS WILL ONLY DROP SLIGHTLY TO LIKELY TOWARD MORNING.
COULD ALSO SEE SOME BLOWING SNOW TODAY AS BUFKIT SUGGESTS GUSTS TO
30 MPH OR MORE.
WITH THICK CLOUDS AROUND TODAY ALONG WITH EVAPORATIVE
COOLING...COLDER NAM MOS AND ALLBLEND TEMPERATURES IN THE
LOWER 30S NORTH TO THE MID 30S SOUTH LOOK GOOD.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 322 AM EDT SUN MAR 24 2013
MODELS AGREE THAT THROUGH THEIR QPF FIELDS THAT THE SNOW WILL BE
WINDING DOWN ON MONDAY WITH ONLY LINGERING SMALL SNOW SHOWER CHANCES
THROUGH TUESDAY. FINALLY...COULD SEE SOME CLEARING AND THE COLDEST
TEMPERATURES OF THE WEEK TUESDAY NIGHT WITH THE SNOW PACK SERVING TO
MAXIMIZE RADIATIONAL HEAT LOSS TO SPACE.
AFTERNOON TEMPERATURES WILL BE WELL BELOW NORMAL WITH THE
SNOW...NORTHWEST WINDS AND CLOUD COVER.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
ISSUED AT 355 AM EDT SUN MAR 24 2013
THE LONG TERM PERIOD WILL START OUT WITH HIGH PRESSURE AT THE
SURFACE AND RIDGING ALOFT. AS A RESULT...DRY CONDITIONS WILL
PREVAIL INTO FRIDAY. HOWEVER...LATEST REGIONAL INITIALIZATION
STILL WANTS TO BRING SLIGHT CHANCES FOR PRECIP INTO CENTRAL
INDIANA ON FRIDAY AND SATURDAY DUE TO A VERY SUBTLE WAVE IN THE
UPPER FLOW. AT THIS TIME...HAVE NOT SEEN ENOUGH CONSISTENCY IN
MODELS TO DIVERT FROM THAT FORECAST...SO WILL KEEP THE POPS WITH
LATEST INITIALIZATION. A SLIGHT WARMING TREND THROUGH THE EXTENDED
PERIOD WOULD KEEP ANY PRECIP THAT FALLS IN THE FORM OF RAIN.
&&
.AVIATION /DISCUSSION FOR 241800Z TAF ISSUANCE/...
ISSUED AT 126 PM EDT SUN MAR 24 2013
CONDITIONS WILL RAPIDLY DETERIORATE LATE THIS AFTERNOON TO VLIFR
WITHIN HEAVY SNOW. IFR AND LOWER CONDITIONS WILL PERSIST INTO
MONDAY AFTERNOON.
CENTRAL INDIANA REMAINS WITHIN A DRY SLOT IN THE WAKE OF THE
MORNING SNOW. THE CALM BEFORE THE STORM IF YOU WILL AS HEAVY
PRECIP MOVING EAST ACROSS ILLINOIS AHEAD OF A DEEPENING LOW
PRESSURE. LOW LEVEL THERMAL ANALYSIS STILL SHOWING A WARM PUNCH
ALOFT MOVING ACROSS THE SOUTHERN HALF OF THE FORECAST AREA OVER
THE NEXT 3-4 HOURS BEFORE 850MB TEMPS CRASH. THIS IS LIKELY TO
ENABLE A PERIOD OF MIXING WITH RAIN...SLEET AND SNOW AT KBMG
BEGINNING AROUND OR SHORTLY AFTER 20Z. MAY EVEN SEE A BIT OF SLEET
MIX AT KIND IN THE 20-21Z TIME PERIOD. ANY MIXING WILL BE SHORT-
LIVED HOWEVER AS EVAPORATIVE COOLING TAKES PLACE THROUGH THE
BOUNDARY LAYER...WITH PRECIP CHANGING TO ALL SNOW AT BOTH KIND AND
KBMG AFTER 21Z.
SNOW WILL BECOME HEAVY BY EARLY EVENING AT ALL TERMINALS AS AXIS
OF DEEPEST FORCING WITH A STRONG WELL DEVELOPED TROWAL SETS UP IN
THE VICINITY OF THE I-70 CORRIDOR. CONSIDERING REPORTS TO THE WEST
OVER MISSOURI AND ILLINOIS AND THE ANTICIPATION THAT THE LOW
STRENGTHENS FURTHER AS IT MOVES INTO THE REGION THIS EVENING...
EXPECT A 3-6 HOUR PERIOD OF VERY HEAVY SNOWFALL WITH VISIBILITIES
AT OR UNDER 1/4SM. CONVECTIVE POTENTIAL AS WELL THROUGH THE
EVENING...ENHANCING SNOWFALL RATES WITHIN ANY THUNDERSNOW. HAVE
LEFT OUT ANY CB MENTION AT THIS TIME...BUT GREATEST POTENTIAL FOR
THUNDERSNOW WILL BE WITHIN THE HEAVIEST SNOWFALL DURING THE
EVENING.
HEAVIEST SNOW WILL SHIFT NORTH OF I-70 BEFORE SLIDING BACK TO THE
SOUTH/EAST IN THE 06-12Z TIME PERIOD. WHILE 1/4SM HEAVY SNOW MAY
CONTINUE THROUGH THIS TIME...FORCING ALOFT IS GRADUALLY WEAKENING
WITH THE STORM SHIFTING TO THE EAST. WILL CARRY 1/2SM AND MODERATE
SNOW THROUGH THE PERIOD AND LET LATER SHIFTS DETERMINE ADDITIONAL
CHANGES AS CONDITIONS EVOLVE OVERNIGHT. SNOW WILL DIMINISH IN
COVERAGE AND INTENSITY FROM NORTHWEST TO SOUTHEAST THROUGH EARLY
MONDAY AFTERNOON...BUT REMAIN ACROSS THE REGION THROUGHOUT THE
DAY. MAINTAIN IFR CONDITIONS THROUGH 18Z MONDAY. NORTHEAST WINDS
THIS AFTERNOON WILL BACK TO NORTHERLY THIS EVENING...THEN N/NW LATE
TONIGHT INTO MONDAY. GUSTS AT 25 TO 30KTS ARE POSSIBLE THROUGHOUT
THE PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL NOON EDT MONDAY FOR INZ021-028>031-
035>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...MK
NEAR TERM...CP
SHORT TERM...MK
LONG TERM....TDUD
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1252 PM CDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 923 AM CD /ISSUED 927 AM CDT SUN MAR 24 2013/
T SUN MAR 24 2013
A QUICK UPDATE SENT TO ADJUST PAST FALLEN SNOW TOTALS FROM
OVERNIGHT...WHICH NOW ARE CERTAIN TO HAVE BEEN 1 TO 3 INCHES FROM
EAST CENTRAL IOWA THROUGH WEST CENTRAL ILLINOIS. AFTER A MINOR
LULL IN SNOW EARLY THIS MORNING...WE ARE NOW SEEING A PUSH OF
RENEWED LIFT WHICH LOOKS TO AFFECT THE SOUTHERN 1/3 THIS MORNING.
THIS IS ALREADY CREATING HEAVY SNOW RATES IN OUR FAR SOUTH. SINCE
1/4 MILE HEAVY SNOW IS INTENSE ENOUGH NOT TO CARE ABOUT MARGINAL
TEMPERATURES VS LIGHT SNOW...OUR AMOUNT NEED TO BE RAISED. I AM
NOW GOING FOR DAYTIME ACCUMS OF 2 TO 4 INCHES IN THE SOUTH
1/3...WHICH WOULD TAKE EVENT TOTALS THROUGH 7 PM TONIGHT INTO THE
4 TO 7 RANGE. WHILE HIGH END ADVISORY AMOUNTS...THE REPORTED
AFFECTS IN THE SOUTH STILL SHOW WET ROADS...WITH SOME SLUSH...THUS
NO PLANS TO CHANGE HEADLINES ARE CONSIDERED AT THIS TIME.
FARTHER NORTH...MARGINAL TEMPS AND LIGHTER SNOWS SHOULD KEEP OUR
GOING FORECAST IN GOOD TRACK FOR NOW.
ERVIN
&&
.SYNOPSIS...
ISSUED AT 322 AM CDT SUN MAR 24 2013
06Z SFC ANALYSIS HAS THE LOW IN NORTHERN MISSISSIPPI WITH AN
INVERTED TROF INTO MISSOURI. ANOTHER TROF RAN FROM EASTERN MINNESOTA
INTO EASTERN IOWA. DEW POINTS WERE IN THE TEENS AND 20S OVER THE
GREAT LAKES AND MID MISSISSIPPI VALLEY WITH 30S AND HIGHER FROM THE
OHIO VALLEY ON SOUTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 322 AM CDT SUN MAR 24 2013
OVERALL AN INTERESTING SYSTEM. THE TRENDS OF BRINGING THE SYSTEM
NORTH HAVE ENDED UP BEING INCORRECT WITH THE MAIN LOW PASSING WELL
SOUTH OF THE AREA.
SATELLITE/RADAR SHOWS A BREAK IN THE SNOW ACROSS NORTHERN MISSOURI
BUT RAP TRENDS AND RECENT WATER VAPOR TRENDS INDICATE THIS BREAK IN
THE SNOW IS FILLING. THE WAA TOOL INDICATES THE BETTER SNOW WILL BE
ACROSS THE SOUTH IN THE HEADLINE AREA. HOWEVER...TEMPERATURES AT OR
JUST BELOW FREEZING IS ALLOWING SOME MELTING TO OCCUR WITH
ACCUMULATIONS BEING ON ELEVATED SURFACES. PAVEMENT TEMPERATURES ARE
AT OR ABOVE FREEZING SO MELTING IS OCCURRING THERE AS WELL.
SO...WILL CONTINUE WITH THE CURRENT HEADLINES AS IS. THE HWY 20
CORRIDOR HAS NOT YET SEEN ANY SNOW BUT THAT SHOULD CHANGE THIS
MORNING AS THE NEXT ROUND OF FORCING MOVES INTO THE AREA. INDIRECT
SOLAR INSOLATION WILL HELP PUSH TEMPERATURES ABOVE FREEZING DURING
THE DAY SO ADDITIONAL MELTING AND COMPACTION WILL OCCUR.
THE FURTHER SOUTH PASSAGE OF THE SYSTEM AND WARM TEMPERATURES WILL
HELP SUPPRESS OVERALL SNOWFALL AMOUNTS. IN THE ADVISORY AREA THE
EXTREME SOUTH PART OF THE CWFA SHOULD SEE 3-4 INCHES BY EVENING WITH
1-2 BY THE TIME ONE REACHES THE I-80 CORRIDOR. NORTH OF HWY 30
AMOUNTS SHOULD BE APPROACHING AN INCH.
TONIGHT...LIGHT SNOW WILL CONTINUE WITH IT ENDING ACROSS THE
NORTHERN THIRD OF THE CWFA AFTER MIDNIGHT. SOUTH OF A KOTM TO KGBG
LINE AMOUNTS AROUND OR JUST OVER AN INCH ARE EXPECTED WITH NOT QUITE
AN INCH AROUND THE I-80 CORRIDOR. NORTH OF HWY 30 A DUSTING TO ONE
HALF INCH IS EXPECTED. ..08..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 322 AM CDT SUN MAR 24 2013
LIGHT SNOW TO EXIT FAR SOUTHERN COUNTIES MON AM WITH PASSAGE
OF ELONGATED WEST-EAST UPPER TROUGH ON BACKSIDE OF OHIO VLY
SHORTWAVE. FEW FLURRIES MAY LINGER ACROSS ENTIRE AREA MON
WITH CYCLONIC FLOW AND COLD ADVECTION. 925 MB TEMPS AROUND
-5C SUPPORTS HIGHS MAINLY IN THE MIDDLE 30S. MON NGT... WITH
CONTINUED COLD ADVECTION AND CYCLONIC FLOW EXPECT PARTLY TO
MOSTLY CLOUDY SKIES AND THUS STAYED NEAR OR JUST ABOVE WARM
SIDE OF GUIDANCE ON LOWS. HOWEVER... AS CLOUDS GO SO GO THE
LOW TEMPS AND WILL NEED TO WATCH FOR POSSIBLY MORE CLEARING
AND COLDER LOWS WITH SOME SUGGESTION OF WEAK MID/UPPER LEVEL
RIDGING IN WAKE OF UPPER TROUGH.
TUE-TUE NGT... CYCLONIC FLOW TO KEEP AT LEAST PARTLY CLOUDY
SKIES TUE ESPECIALLY EASTERN 1/3-1/2... WITH ONLY SLIGHT
MODERATION ON TEMPS BY 1-3 DEGS FROM THOSE OF MON. CANT RULE
OUT FEW FLURRIES OR EVEN BRIEF SNOW SHOWER FAR EAST WITH
ENOUGH HEATING AS MODELS DEPICT WEAK ENERGY ROTATING DOWN
THROUGH WI AND NORTHERN IL TUE PM. PARTLY CLOUDY TO MOSTLY
CLEAR SKIES EXPECTED TUE NGT WITH SFC RIDGE AXIS BUILDING IN.
LOWS MAINLY UPPER TEENS TO LOWER 20S... BUT IF WINDS SHOULD
GO LIGHT FOR ANY LENGTH OF TIME THEN COULD SEE MINS AS COLD AS
AROUND 14-17 DEGS ESPECIALLY WEST/SOUTHWEST SECTIONS BEING IN
CLOSE PROXIMITY TO RIDGE AXIS.
WED-SAT... OVERALL MODERATING TEMPS LOOK TO BE IN STORE DURING
THE PERIOD... WITH TEMPS EDGING NEAR NORMAL TOWARD THE
END OF PERIOD AS THE PERSISTENT BLOCKING PATTERN OVER NORTH
AMERICA RESPONSIBLE FOR LOCKING IN THE COLD AIR IS SHOWN
TO BREAK DOWN. WITH THIS WARMING TREND WILL ALSO COME AT LEAST
SOME THREAT OF MAINLY LIGHT PRECIPITATION OVER THE LATTER HALF OF
THE WEEK BEING IN FAIRLY CLOSE PROXIMITY TO MID LEVEL BAROCLINIC
ZONE AND SUBJECT TO WEAK IMPULSES PROPAGATING DOWN IN NORTHWEST
FLOW ALOFT. CONSENSUS MODEL INTRODUCED SEVERAL PERIODS OF SLIGHT
CHC POPS FROM WED NGT THROUGH FRI... BUT GIVEN THE WEAK AND
VARYING SIGNAL FROM THE MODELS IT WAS COLLABORATED WITH
SURROUNDING OFFICES TO LOWER PRECIPITATION CHANCES BELOW MENTION
THROUGH FRI AND AWAIT FOR SOME BETTER CONSISTENCY. THE SIGNAL IS
STRONGER AND MORE CONSISTENT BY NEXT WEEKEND AND HAVE THEREFORE
LEFT IN PRECIPITATION CHCS BY SAT NGT. BEYOND THE SCOPE OF THE
EXTENDED... THE PATTERN REMAINS QUITE ACTIVE WITH THE MEDIUM RANGE
MODELS POINTING TO ANOTHER STORM SYSTEM POSSIBLY IMPACTING THE
AREA TOWARD THE MIDDLE PORTION OF THE FIRST WEEK OF APRIL WITH THE
POTENTIAL FOR AT LEAST MODERATE PRECIPITATION AMOUNTS WITH MAINLY
RAIN AND POSSIBLY SOME SNOW SUGGESTED. 05
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1248 PM CDT SUN MAR 24 2013
A SLOW MOVING STORM SYSTEM WILL BRING PERSISTENT LIGHT TO MODERATE
SNOW TO EASTERN IOWA AND ILLINOIS THROUGH LATE TONIGHT...THEN
FLURRIES THROUGH MONDAY. THIS WILL RESULT IN PERSISTENT MVFR/IFR
CONDITIONS TODAY THROUGH TONIGHT...WITH CIGS OF 1000 TO 2000 FT
COMMON...AND VISIBILITIES BETWEEN 1 AND 5 MILES COMMON. A PERIOD
OF 1/2 MILE VIS IN MODERATE SNOW IS EXPECTED TO AFFECT MLI AND BRL
OCCASIONALLY THROUGH 22Z TODAY. DURING THIS PERIOD...CIGS MAY ALSO
LOWER TO 500 FT AT TIMES. OVERNIGHT...GENERALLY 3 TO 6 MILE
VISIBILITIES ARE EXPECTED IN LIGHT SNOW AND FOG.
ERVIN
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR
IAZ087>089-098-099.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ025-
026-034-035.
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MOZ009-
010.
&&
$$
UPDATE...ERVIN
SHORT TERM...08
LONG TERM...05
AVIATION...ERVIN
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
149 PM EDT SUN MAR 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 502 AM EDT SUN MAR 24 2013
WV IMAGERY AND RUC ANALYSIS INDICATED PERSISTENT HIGH LATITUDE
MID/UPPER LEVEL RIDGING FROM SCANDINAVIA INTO NORTHERN CANADA
RESULTING IN LOWER HEIGHTS AND COLDER AIR TO THE SOUTH ACROSS SRN
CANADA AND THE NRN CONUS. A WEAK RIDGE EXTENDED ACROSS THE WRN
GREAT LAKES BTWN MID LEVEL LOWS OVER THE DAKOTAS AND CANADIAN
MARATIMES. AT THE SFC...WEAK NE FLOW PREVAILED BETWEEN HIGH PRES
OVER SASK INTO NRN MANITOBA AND LOW PRES OVER THE LOWER MS VALLEY.
IR SATELLITE LOOP SHOWED AN EXTENSIVE AREA OF CLOUDS ACROSS THE
REGION WITH A RELATIVELY SMALL CLEAR AREA NE OF LAKE SUPERIOR.
WITH GENERALLY WEAK ONSHORE WINDS INTO NRN UPPER MI
OVERNIGHT...RADAR INDICATED NO PCPN. HOWEVER...AS WINDS INCREASE OUT
OF THE NORTHEAST AND 850 MB TEMPS REMAIN NER -11C...EXPECT SOME
LIGHT SNOW MAY STILL DEVELOP OVER THE WEST AND N CNTRL LOCATIONS
WHERE UPSLOPE FLOW PREVAILS. SINCE TEMPS IN THE MOIST LAYER REMAINED
BORDERLINE TO SUPPORT ICE CRYSTALS...A MIX OF -SN/FLURRIES/-FZDZ MAY
BE POSSIBLE. MODELS SUGGEST THAT THE DRY AIR TO THE NORTHEAST WILL
SPREAD ACROSS LAKE SUPERIOR INTO UPPER MI THIS AFTERNOON. THIS
SHOULD BRING AN END TO ANY PCPN THAT DEVELOPS EARLY TODAY. SOME
CLEARING MAY ALSO SPREAD FROM EAST INTO CNTRL UPPER MI BY LATE THIS
AFTERNOON WHICH SHOULD HELP BOOST TEMPS INTO THE LOWER TO MID 30S.
THE MODELS WERE CONSISTENT IN BRINGING ANOTHER BATCH OF 925-700 MB
MOISTURE INTO THE AREA FROM THE NORTHEAST TONIGHT. THIS WILL BRING
INCREASING CHANCES FOR LIGHT LAKE EFFECT SNOW...ESPECIALLY AFT
06Z...TO AREAS FAVORED BY UPSLOPE NNE FLOW IN N CNTRL AND WRN UPPER
MI. SINCE DEEPER MOISTURE TO AROUND -12C IS LIKELY...-FZDZ CHANCES
WILL BE REDUCED. THE CLOUDS WILL ALSO KEEP TEMPS FROM FALLING OFF
TOO MUCH WITH MIN READINGS AGAIN ABOVE NORMAL....IN THE LOW TO MID
20S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 443 AM EDT SUN MAR 24 2013
OUR STEADY NORTHERLY FLOW OFF LAKE SUPERIOR WILL CONTINUE THROUGH
WEDNESDAY...WITH LIGHT PRECIPITATION POSSIBLE NEARLY EVERY DAY NEAR
LAKE SUPERIOR. LOOK FOR TEMPERATURES TO SLOWLY INCREASE EACH
DAY...WITH SOUTH CENTRAL AREAS NEARING 40 DEGREES FOR A HIGH ON
THURSDAY...AND REMAINING IN THE UPPER 30S AND LOW 40S TO WRAP UP THE
WORK WEEK AND START THE UPCOMING WEEKEND.
THE NEXT GOOD SURGE OF PRECIPITATION WILL BE MONDAY THROUGH TUESDAY
MORNING...AS THE MID ATLANTIC LOW ROTATES MOISTURE BACK TOWARD THE
UPPER GREAT LAKES REGION. STILL IT WILL BE SET UP AOB ABOUT
800MB...WITH THE DGZ HOVERING AT THE TOP OF THIS MOISTURE LAYER TO
AROUND 600MB. WHILE THE MOST PRISTINE SNOW CRYSTALS WILL NOT BE
EXPECTED...850MB TEMPS HOVERING BETWEEN -10 AND -12C. SNOW AMOUNTS
AROUND A HALF INCH EVERY 6 HOURS WILL BE POSSIBLE MONDAY THROUGH
TUESDAY MORNING...HIGHEST OVER THE ELEVATED TERRAIN OF MARQUETTE
COUNTY...AND ACROSS WESTERN GOGEBIC AND ONTONAGON COUNTIES.
THE 500MB TROUGH WILL LIKELY REMAIN ENTRENCHED ACROSS CENTRAL AND
EASTERN UPPER MICHIGAN THROUGH TUESDAY NIGHT INTO WEDNESDAY. AT THAT
POINT NW FLOW LOOKS TO TAKE OVER ALOFT...WITH A SERIES OF WEAKER
WAVES SLIDING NEAR THE UPPER GREAT LAKES. WHILE WE DO HAVE SLIGHT
CHANCE POPS MENTIONED FOR DAY 5/FRIDAY INTO DAY 6/SATURDAY...THE
CONFIDENCE IS VERY LOW. THE ECMWF KEEP LOW PRESSURE STUCK UP NEAR
JAMES BAY AND HUDSON BAY ON FRIDAY...WITH HIGH PRESSURE STRETCHING
FROM SOUTH CENTRAL CANADA THROUGH THE UPPER GREAT LAKES. A WEAK COLD
FRONT MAY CROSS THURSDAY NIGHT INTO FRIDAY. THE 00Z MODEL RUNS LOOK
LESS THAN IMPRESSIVE WITH THE CHANCE FOR MEASURABLE PRECIP THROUGH
THE END OF THE FORECAST PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 146 PM EDT SUN MAR 24 2013
UPSLOPE PRECIPITATION...A MIX OF -FZDZ AND -SHSN ASSOCIATED WITH
LINGERING LOW-MID LEVEL MOISTURE WILL CONTINUE THROUGH AROUND 21Z AT
KIWD AND KSAW. POCKET OF DRY AIR SEEN DIVING SOUTHWESTWARD ACROSS
LAKE SUPERIOR WILL DIMINISH THE MORE EXTENSIVE CLOUD COVER AND
PRECIP FOR A BRIEF PERIOD AT ALL THREE SITES...HOWEVER
SCATTERED-BROKEN MVFR-VFR DECK IS EXPECTED TO REMAIN IN PLACE FOR
THE MOST PART AS LAKE EFFECT CLOUDS DEVELOP IN ITS WAKE.
ADDITIONALLY...HIGH-MID LEVEL CLOUDS FROM THE PASSING SYSTEM TO THE
SOUTH ARE EXPANDING OVER UPPER MICHIGAN. OVERNIGHT PRECIPITATION
WILL START UP AGAIN...MAINLY IN THE FORM OF SNOW...AT ALL THREE
SITES. THIS WILL LAST THROUGH THE AFTERNOON HOURS ON MONDAY.
CONDITIONS ARE NOT EXPECTED TO DROP BELOW MVFR.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 502 AM EDT SUN MAR 24 2013
HIGH PRESSURE OVER CENTRAL CANADA WILL KEEP A RIDGE OVER THE UPPER
GREAT LAKES REGION TODAY. BUT AS A LOW PRESSURE SYSTEM
DEPARTS THE CENTRAL PLAINS AND MOVES THROUGH THE OHIO RIVER VALLEY
THROUGH MONDAY NIGHT...THE RIDGE WILL WEAKEN AND SHIFT WEST. THIS
WILL LEAD TO PERSISTENT NORTHERLY FLOW ACROSS THE AREA...ALTHOUGH
THE WINDS SHOULD BE AT OR BELOW 25 KNOTS. AS THE LOW SHIFTS OFF
THE ATLANTIC SEABOARD ON TUESDAY...HIGH PRESSURE WILL BEGIN TO SHIFT
BACK TO THE EAST AND COVER THE UPPER GREAT LAKES FROM TUESDAY NIGHT
THROUGH THE REST OF THE WORK WEEK. THIS WILL KEEP THE NORTHERLY
WINDS BELOW 15KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...MCD
MARINE...JLB
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1217 PM CDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 1030 AM CDT SUN MAR 24 2013
FORECAST LOOKS TO BE ON TRACK WITH MAJOR WINTER STORM IMPACTING
THE AREA TODAY INTO THIS EVENING. SOME PARTS OF CENTRAL MISSOURI
ARE ALREADY REPORTING 7+ INCHES OF SNOW ON THE GROUND...WITH MANY
REPORTS OF HEAVY SNOW AND THUNDERSNOW ALL ALONG THE I-70 CORRIDOR
IN MISSOURI. THERE HAVE ALSO BEEN MORE REPORTS OF SLEET THAN
EARLIER ANTICIPATED IN THE WARM ADVECTION PRECIP STILL ONGOING
ACROSS PARTS OF SOUTHWEST/SOUTH CENTRAL ILLINOIS. HAVE UPDATED THE
FORECAST TO ADD IN SOME SLEET IN THESE AREAS...AND A SMALL PART OF
SOUTHEAST MISSOURI. OTHERWISE...LITTLE CHANGE TO THE GOING
FORECAST AT THIS TIME.
CARNEY
&&
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 336 AM CDT SUN MAR 24 2013
PRIMARY FCST ISSUE FOR TODAY IS THE ONGOING WINTER STORM. WAA PCPN
WHICH DVLPD ACROSS THE AREA LAST NIGHT BRIEFLY CHANGED OVER TO A
RAIN/SNOW MIX AND EVEN SWITCHED OVER TO PURE SNOW IN SOME
LOCATIONS BEFORE ENDING. THERE WILL BE A BRIEF BREAK EARLY THIS
MORNING BETWEEN THE DEPARTING WAA PCPN AND THE HEAVIER SNOW
ASSOCIATED WITH THE DEFORMATION ZONE WHICH HAS ALREADY DVLPD IN
ERN KS AND WRN MO. MODELS ARE IN GENERALLY GOOD AGREEMENT THIS
MORNING WITH THE TRACK OF THE LOW PRESSURE SYSTEM...ESPECIALLY THE
ECMWF WHICH HAS BEEN FAIRLY CONSISTENT WITH THE TRACK OF THE H85
LOW ALTHOUGH THE 24/00Z RUN IS SOMEWHAT SLOWER THAN THE 23/00Z RUN
BETWEEN 12Z AND 18Z. THE TRACK OF THE H85 CIRCULATION CENTER FROM
NEAR KSGF/KUMN TO NEAR KFAM/KMDH IS VERY FAVORABLE FOR HEAVY SNOW
ACROSS THE CENTRAL PART OF THE CWA BASED ON LOCAL CLIMATOLOGY
PLOTS.
THERE ARE TWO ASPECTS OF THIS EVENT THAT REALLY CAUGHT MY
ATTENTION. FIRST...BUFKIT CROSS SECTIONS FROM A COUPLE OF MODELS
/INCLUDING THE RAP AND SREF/ SHOW VERY STRONG LIFT FOCUSED THROUGH
A RESPECTABLY DEEP DENDRITIC GROWTH ZONE WHICH IS OCCASIONALLY
SUPERSATURATED WITH RESPECT TO ICE. THIS IS ESPECIALLY TRUE
BETWEEN 15Z AND 00Z. SECOND...NO MATTER HOW YOU SLICE THE
ATMOSPHERE...THERE ARE INDICATIONS OF MODEST INSTABILITY /AT LEAST
FOR A WINTER EVENT/ ACROSS PARTS OF MO/IL TODAY. FCSTS OF H7-H5
LAPSE RATES EXCEED 7 DEG C/KM ACROSS THE SRN HALF OF THE CWA ON
THE RAP/WRF/SREF/NAM/GFS/UKMET AND EVEN THE ECMWF FCST EXCEEDS 6.5
DEG C/KM. BUFKIT SOUNDINGS ALSO SHOW UP TO 50 J/KG OF ELEVATED
CAPE AT TIMES. TAKEN TOGETHER...THESE TWO ITEMS SUGGEST THAT THERE
WILL BE PERIODS OF EFFICIENT SNOWFALL PRODUCTION WITHIN THE
DEFORMATION ZONE ALONG WITH OCCASIONAL CONVECTIVE ELEMENTS WHICH
WILL LOCALLY ENHANCE SNOWFALL RATES. IN TERMS OF SNOWFALL
AMOUNTS...IT STILL LOOKS LIKE A SOLID 6-8 INCHES OF SNOW ACROSS
THE WINTER STORM WARNING AREA WITH HIGHER AMOUNTS POSSIBLE.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 24 2013
(TONIGHT - MONDAY NIGHT)
MODELS HAVE ALL COME INTO A HARMONIOUS CONFLUENCE OF SOLUTIONS WITH
THE 00Z RUNS...WITH THE AGREED UPON TRACK MOST SIMILAR TO THE ECMWF
24HRS AGO...WITH THE GFS/NAM MORE SLY...AND THE GEM MORE NLY...AND
PLACES THIS STORM IN ABOUT THE MOST PERFECT SPOT TO MAXIMIZE SNOW
TOTALS ACROSS THE I-70 CORRIDOR WITH AN ELONGATED H850 LO TRACKING
THRU SRN MO AND SRN IL. ANOTHER TREND...THIS ONE TEMPORAL...HAS
BEEN TO SLOW DOWN THE EWD TRANSLATION OF THE STORM BY ABOUT 6HRS...
MEANING THE DEF ZONE PCPN FROM IT WILL LINGER WELL INTO THIS EVENING
FOR THE IL COUNTIES AND AREAS JUST W OF THE MS RIVER AND PERHAPS
EARLY OVERNIGHT FOR PARTS OF SWRN-SRN IL. SNOWFALL TOTALS HAVE BEEN
BUMPED UP AS A RESULT OF THE SLOWER EXIT...WITH AN ADDITIONAL 2-3"
FOR MUCH OF THE IL COUNTIES AND AROUND AN INCH MORE FOR THE REST.
HAVE EXPANDED THE REACH OF THE WARNING BACK TO THE W A BIT MORE. BY
THE TIME IT IS ALL SAID AND DONE...THE PALM SUNDAY SNOWSTORM OF 2013
IS EXPECTED TO BE ONE OF THOSE ONCE-IN-A-GENERATION TYPE STORMS FOR
OCCURRING SO LATE IN THE YEAR AND BEING SO POTENT.
THIS POTENT STORM SYSTEM WILL BE EXITING JUST AS ANOTHER...WEAKER...
SYSTEM MOVES IN. THIS SYSTEM IS THE OLD MONTANA LO THAT IS EXPECTED
TO OPEN UP LATER TODAY AND GET SUCKED IN THE UNDERTOW OF TODAY AND
THIS EVENING/S STORM SYSTEM...BECOMING SHEARED BY THE TIME IT
REACHES OUR AREA LATER TONIGHT AND CONTINUING INTO MONDAY...BUT WITH
ENOUGH TO KEEP EITHER THE LIGHT SNOW OR SNOW SHOWERS GOING THRU LATE
MONDAY. SNOW ACCUMS LOOK TO BE AROUND AN ADDITIONAL INCH FOR MOST
AREAS...BUT OVER THE COURSE OF ANOTHER 12HRS OR SO. DEPENDING ON
HOW THIS ALL WORKS OUT...THE NATURE OF SHSN MAY SEE LOCALIZED HIGHER
AMOUNTS POSSIBLE. THE PERSISTENT LO CLOUDS SHOULD HANG IN TOUGH
THRU MONDAY AND WITH NW LO LEVEL WINDS AND LOTS OF FRESH SNOW
PACK...WHAT INSOLATION DOES MAKE IT THRU WILL GET MOSTLY BOUNCED
BACK...AND SO LOOK FOR MINIMAL TEMP RISES THIS DAY AS WELL...AND MOS
SEEMS TO HIGH ONCE AGAIN. UNDERCUT THE COLDER MET MOS NUMBERS BY A
COUPLE DEGS.
PERSISTENT CYCLONIC FLOW AND CLOUDS CONTINUE INTO MONDAY NIGHT AND
HAVE KEPT MENTION OF FLURRIES.
(TUESDAY - SATURDAY)
NW UPPER LEVEL FLOW WILL THEN CONTINUE FOR THE REMAINDER OF THE WEEK
CONTINUING THE BELOW AVERAGE TEMP REGIME AND ROUNDING OUT OUR RATHER
COLD MARCH. AN INVERTED TROF FOR THURSDAY AND THEN A CDFNT FOR
FRIDAY LOOK TO GIVE US SOME PCPN CHCS BY LATE IN THE WEEK...BUT
UNLIKE THE START OF THE WEEK...THESE PCPN CHCS SHOULD BE IN THE FORM
OF LIQUID.
TES
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1213 PM CDT SUN MAR 24 2013
DEFORMATION BAND OF SNOW WILL CONTINUE TO INTENSIFY THIS AFTERNOON
ALONG THE I-70 CORRIDOR AS THE UPPER LEVEL SYSTEM BEGINS TO PIVOT.
EVENTUALLY HEAVIEST SNOW WILL BEGIN TO WORK ITS WAY EAST...BY THIS
EVENING. IFR CONDITIONS TO CONTINUE WITH NORTH TO NORTHWEST WIND.
GRADUAL IMPROVEMENT OF CONDITIONS ANTICIPATED FROM WEST TO EAST
LATE TONIGHT AND TOMORROW MORNING...ALTHOUGH LIGHT SNOW AND
FLURRIES WILL PROBABLY CONTINUE AS UPPER LEVEL TROF REMAINS OVERHEAD.
SPECIFICS FOR KSTL...
IFR CONDITIONS WILL CONTINUE WITH PERIODS OF HEAVY SNOW THROUGH
THIS AFTERNOON. DEFORMATION BAND WILL SLOWLY MOVE EAST OF THE AREA
THIS EVENING WITH SNOW TAPERING OFF...VISIBILITY IMPROVING. LIGHT
SNOW AND FLURRIES ANTICIPATED TO REMAIN ACROSS THE AREA THROUGH
MONDAY MORNING THOUGH AS UPPER LEVEL TROF AXIS REMAINS OVER THE
AREA. NORTH WIND WILL BECOME NORTHWEST AND GUSTY THIS AFTERNOON AS
SURFACE LOW PULLS EAST OF THE AREA.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CRAWFORD
MO-IRON MO-MADISON MO-REYNOLDS MO-ST. FRANCOIS MO-STE.
GENEVIEVE MO-WASHINGTON MO.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR JEFFERSON MO-
LINCOLN MO-PIKE MO-ST. CHARLES MO-ST. LOUIS CITY MO-ST.
LOUIS MO.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR AUDRAIN MO-
BOONE MO-CALLAWAY MO-COLE MO-FRANKLIN MO-GASCONADE MO-KNOX
MO-LEWIS MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-
OSAGE MO-RALLS MO-SHELBY MO-WARREN MO.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR RANDOLPH
IL.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR ADAMS IL-
BOND IL-BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-
JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...CORRECTED
NWS HASTINGS NE
101 PM CDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 101 PM CDT SUN MAR 24 2013
TEMPS/DWPTS IN GOOD SHAPE. MADE SOME MINOR ADJUSTMENTS TO CLOUDS.
VIS SATL SHOWS WIDESPREAD STRATOCU DEVELOPING BETWEEN LBF-TIF AND
HEADING FOR LXN. LNX 88D AND A CALL FROM LBF INDICATES FLURRIES.
SO FLURRIES HAVE RETURNED TO THE FCST FOR THIS AFTN. STRATOCU ARE
STRUGGLING TO FORM OVER MUCH OF THE FCST AREA. SO HIGHEST
CONFIDENCE IS W OF HWY 183. FCST SKY COVER THIS AFTN MAY NEED TO BE
LOWERED E OF HWY 183.
UPDATE ISSUED AT 932 CDT SUN MAR 24 2013
CYCLOGENESIS IS UNDERWAY OVER THE MID MS VALLEY. A SHRTWV RIDGE IS
OVER THE FCST AREA IN ITS WAKE AND HAS RESULTED IN CLEARING. 12Z
SOUNDINGS SHOW EXTENSIVE MSTR ALL THE WAY BACK TO MT/ND. SO EXPECT
DIURNAL STRATOCU TO DEVELOP AROUND MIDDAY.
THE BACK EDGE OF THE CIRRUS CANOPY WITH THE MID MS VALLEY LOW WAS
EXITING OUR ERN COUNTIES ALONG HWY 81. THESE AREAS WILL BECOME SUNNY
BY 11 AM.
VIS SATELLITE ALSO SHOW SOME MID-HIGH CLOUDS OVER WY AND NRN CO.
THESE CLOUDS WILL ALSO DIVE SE INTO THE FCST AREA. SO OVERALL EXPECT
A SUNNY MRNG TO TURN P/CLOUDY THIS AFTN.
DID MAKE SOME SUBSTANTIAL ADJUSTMENTS TO SKY FCST FORENOON TO ACCT
FOR CLEARING. WILL CONT TO MONITOR TEMP CURVES.
IT/S COLD! THE CAMBRIDGE CO-OP OBSERVER HAD A LOW TEMP OF 9F. AN
NDOR MESONET SITE IN ARAPAHOE ALSO REPORTED 9F. WIND CHILLS ARE
MOSTLY IN THE SINGLE DIGITS ACROSS THE FCST AREA.
OVERALL A BLUSTERY COLD DAY. 06Z NAM/11Z RAP BUFKIT TIME SECTIONS
SUGGEST PEAK WINDS AVAILABLE FOR MIXING ARE 30-33 KTS. SO NW WINDS
WILL GUST 25-35 MPH...THO LESS FREQUENTLY IN THE 30-35 MPH RANGE.
OTHER THAN SHORT-TERM SKY ALL OTHER FCST ELEMENTS LOOK GOOD.
ANALOGS: LOOKING BACK AT THE FCST ANALOG YEARS FROM 10 DAYS AGO...
THEY HAD A GREAT SIGNAL FOR THIS CURRENT STRETCH OF UNSEASONABLY
COLD MARCH WX. THOSE INCLUDED 1951 52 57 58 62 AND 2006.
UPDATE ISSUED AT 543 AM CDT SUN MAR 24 2013
UPDATED THE FORECAST FOR TODAY TO MAKE MINOR ADJUSTMENTS TO HOURLY
TEMPERATURES...WINDS...AND DEWPOINTS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 509 AM CDT SUN MAR 24 2013
THE MAIN CHALLENGE WILL BE DETERMINING CHANCES FOR FLURRIES/SNOW
SHOWERS TODAY AND TONIGHT.
UPPER LEVEL JET STREAM HAS MADE A DIVE WELL SOUTH OF THE AREA WITH A
RATHER LARGE LONGWAVE TROUGH OVER THE CENTRAL UNITED STATES. THIS
SHOULD ENSURE THAT WE REMAIN WELL BELOW NORMAL TODAY. AT
MID-LEVELS...A SOMEWHAT COMPLEX SCENARIO IS TAKING PLACE. A SET OF
DUMBBELL CLOSED LOWS OCCUPY THE AFOREMENTIONED LONGWAVE
TROUGH...WITH ONE OF THE LOWS TRACKING TO THE EAST ACROSS
SOUTHEASTERN KANSAS. THE SECOND LOW IS LOCATED OVER NORTH DAKOTA.
FOR TODAY...WE SHOULD BE IN AN AREA BETWEEN THE TWO CLOSED
LOW...WITH SOME SHORTWAVE RIDGING. THIS SHOULD KEEP FLURRIES/SNOW
SHOWERS OUT OF THE AREA DURING THE DAY TODAY...AND PERHAPS ALLOW A
PEAK OR TWO AT SOME SUN. WITH 850 MB TEMPERATURES RATHER SIMILAR TO
SATURDAY...AND WITH THE BIT OF CHANCE AT A PEAK OR TWO OF LATE MARCH
SUN...I HAVE BUMPED UP TEMPERATURES A BIT FOR TODAY.
THE APPROACHING CLOSED LOW IS EXPECTED TO FILL TODAY AS IT HEADS
SOUTH. THE LEFTOVER LOBE OF ENERGY WILL ARRIVE THIS EVENING AND
COULD SPAWN MORE FLURRIES/SNOW SHOWERS...WITH BETTER CHANCES TO THE
EAST/NORTHEAST...WITH THE BEST LARGE SCALE TO THE EAST/NORTHEAST. I
WENT WITH SIMILAR LOW TEMPERATURES TONIGHT COMPARED TO THE PREVIOUS
FORECAST WITH ONLY MINOR ADJUSTMENTS. BUMPED UP WIND SPEEDS JUST A
BIT WITH INCREASING LOW-LEVEL LAPSE RATES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 509 AM CDT SUN MAR 24 2013
THIS 6-DAY PERIOD WILL BE HIGHLIGHTED BY WHAT CURRENTLY APPEARS TO
BE A FEW LOW-END CHANCES FOR GENERALLY LIGHT MEASURABLE PRECIP...BUT
MORE IMPORTANTLY TO MANY FOLKS...A LEGITIMATE WARMING TREND BACK
INTO THE 40S AND AT LEAST 50S.
CERTAINLY MONDAY THROUGH TUESDAY THE AREA WILL STILL BE MIRED IN THE
MUCH-BELOW NORMAL COLD AIR. STARTING OFF SUNRISE MONDAY
MORNING...00Z/06Z MODELS SUCH AS THE NAM/GFS/ECMWF ARE IN GOOD
AGREEMENT DEPICTING AN ELONGATED MID LEVEL TROUGH EXTENDING FROM
NORTHWEST-SOUTHEAST ACROSS THE CENTRAL PLAINS...WHICH THEN GRADUALLY
DEPARTS TO THE SOUTHEAST DURING THE DAY...FEEDING INTO THE ENTRANCE
REGION OF A STOUT UPPER LEVEL JET STREAK ACROSS THE SOUTHEAST CONUS.
AT THE SURFACE MONDAY...ALTHOUGH A GRADUAL DECREASE IN WIND SPEEDS
WILL OCCUR DURING THE DAY...THE COMBINATION OF DEEP MIXING AND A
STILL TIGHTENED PRESSURE GRADIENT WILL RESULT IN FAIRLY BREEZY
CONDITIONS WITH SUSTAINED NORTHWEST WINDS AT LEAST 20 MPH GUSTING
25-30 MPH. THESE WINDS WILL RESULT IN ANOTHER VERY COLD DAY FOR LATE
MARCH...WITH WIND CHILL READINGS DURING THE AFTERNOON STRUGGLING TO
REACH THE LOW 20S. ACTUAL AIR TEMPERATURES WILL BE VERY SIMILAR TO
THOSE OF TODAY...WITH LOW TO POSSIBLY MID 30S CWA-WIDE.
PRECIPITATION-WISE...AS NOTED BY THE PAST SEVERAL FORECAST
SHIFTS...THIS IS A FAIRLY CLASSIC SETUP FOR AT LEAST A SLIGHT CHANCE
OF FLURRIES...AS FORCING FROM THE OVERHEAD ELONGATED SHORTWAVE
COMBINES WITH FAVORABLE DENDRITIC TEMPERATURES AROUND -11C IN A LOW
STRATUS LAYER TO SQUEEZE OUT SOME FLAKES. AS NOTED BY PREVIOUS DAY
SHIFT...PARTS OF THE EASTERN CWA COULD EVEN SEE SOME VERY LIGHT
MEASURABLE SNOW OF MAYBE A TENTH OF AN INCH OR TWO...AS SUGGESTED BY
LIGHT QPF EVIDENT IN VARIOUS MODEL FIELDS. AS A RESULT...MAINTAINED
A FLURRY CHANCE IN THE WEST THROUGH THE DAY...BUT ACTUALLY BEEFED UP
ROUGHLY THE NORTHEAST 1/2 OF THE CWA TO A 20 TO 30 PERCENT CHANCE OF
MEASURABLE LIGHT SNOW. THIS SHOULDN/T BE ANY KIND OF IMPACTFUL
SNOW...BUT FELT IT WAS WORTHY OF A SMALL POP AS SOME AREAS COULD SEE
A BIT MORE THAN FLURRIES. BY SUNSET MONDAY NIGHT...THE
AFOREMENTIONED MID LEVEL WAVE WILL BE JUST DEPARTING THE SOUTHERN
END OF THE CWA...AND ALTHOUGH SOME DEGREE OF LOW STRATUS COULD
LINGER THROUGH THE NIGHT...FEEL THE RISK OF LINGERING FLURRIES/LIGHT
SNOW IS LOW ENOUGH BY THEN TO END THE MENTION. TEMP-WISE...ITS VERY
POSSIBLE THAT MONDAY NIGHT COULD IN FACT BE THE COLDEST NIGHT FOR
THE NEXT SEVERAL MONTHS...AS A SURFACE RIDGE AXIS SETTLES IN AND
BREEZES BECOME VERY LIGHT BY SUNRISE. ALTHOUGH LINGERING CLOUDS
COULD WORK AGAINST A MAJOR DROP-OFF...WILL STILL CALL FOR MOST OF
THE CWA SETTLING DOWN TO AT LEAST 14-18 DEGREES. DESPITE THE LIGHT
WINDS...AM NOT OVERLY CONCERNED ABOUT IMPACTFUL FOG DEVELOPMENT...SO
WILL CONTINUE TO OMIT FROM THE FORECAST.
TUESDAY/TUESDAY NIGHT...CONFIDENCE IS RATHER HIGH IN A PRECIP-FREE
24 HOURS...ALTHOUGH WILL ACKNOWLEDGE THAT THE ECMWF CONTINUES TO
SPIT OUT SOME VERY LIGHT QPF NEAR THE SOUTHWEST EDGE OF THE CWA LATE
TUES NIGHT...LIKELY IN RESPONSE TO A MODEST BELT OF LOW-MID LEVEL
THETA-E ADVECTION AS A VERY SUBTLE MID LEVEL SHORTWAVE TROUGH
RIPPLES THROUGH WEST-NORTHWEST FLOW ALOFT. THE THINKING FOR NOW IS
THAT FAIRLY DRY LOW LEVELS WILL WORK AGAINST PRECIP
DEVELOPING...ESPECIALLY OF THE MEASURABLE VARIETY. HOWEVER...IT WILL
BEAR WATCHING AS TEMPERATURE PROFILES WOULD SUGGEST A LOW-END RISK
OF LIGHT FREEZING RAIN IF SOMETHING WERE TO MOVE IN. FOR NOW WILL
LEAVE TUES NIGHT PRECIP FREE THOUGH. BACKING UP TO THE TUESDAY
DAYTIME HOURS...DEVELOPING SOUTHERLY BREEZES SHOULD MARK THE
BEGINNING STAGES OF A NICE WARM-UP...AND NUDGED UP HIGH TEMPS A BIT
GETTING NEARLY ALL AREAS INTO THE LOW OR MID 40S.
WEDNESDAY/WEDNESDAY NIGHT...HAVE MAINTAINED A DRY
FORECAST...ALTHOUGH ITS NOT NECESSARILY A GUARANTEE TO STAY THAT WAY
AS BOTH THE ECMWF/GFS CONTINUE TO BRING A SERIES OF WEAK SHORTWAVES
THROUGH THE PERSISTENT WEST-NORTHWEST FLOW...WHICH COULD SATURATE
THE MID LEVELS JUST ENOUGH TO PRODUCE SOME SPRINKLES OR LIGHT RAIN.
AGAIN...CONFIDENCE JUST ISN/T HIGH ENOUGH TO GO THERE YET.
TEMP-WISE...THE WARM-UP CONTINUES WITH ALL NEBRASKA ZONES AIMED WELL
INTO THE MID-UPPER 40S AND EVEN SOME 50S NEAR/SOUTH OF THE STATE
LINE.
THURSDAY/THURSDAY NIGHT...BROAD WEST-NORTHWEST FLOW JUST KEEPS ON
PERSISTING OVER THE CENTRAL PLAINS...WITH EVEN A HINT OF HEIGHT
RISES AS A RIDGE BUILDS EASTWARD A BIT FROM THE ROCKIES. ALTHOUGH
ODDS ARE REASONABLY HIGH THAT THIS 24 HOURS WILL REMAIN
DRY...ESPECIALLY THE DAYTIME...WILL CONTINUE TO HANG ONTO A SLIGHT
CHANCE OF RAIN THURSDAY NIGHT FROM THE PREVIOUS FORECAST...ALTHOUGH
THIS CHANCE MAY VERY WELL BE DROPPED IN THE COMING DAYS. CONTINUED
MODIFICATION OF THE LOW LEVEL TEMPERATURE FIELDS RAISES CONFIDENCE
IN WIDESPREAD 50S FOR THURSDAY...WHICH WOULD MARK THE FIRST TIME IN
9-13 DAYS THAT MOST OF THE CWA HAS CRACKED 50.
FRIDAY/FRIDAY NIGHT...THE CWA-WIDE SLIGHT CHANCES OF RAIN SHOWERS
WERE MAINTAINED FROM THE PREVIOUS FORECAST...BUT AGAIN ITS BY NO
MEANS LOOKING LIKE A WIDESPREAD MEASURABLE RAIN RISK. THAT BEING
SAID...GRADUAL MOISTENING OF THE LOW LEVELS EVIDENT AT 850 MILLIBARS
COULD ACTUALLY GENERATE SOME WEAK INSTABILITY BY THIS TIME...AND
THUS ITS NOT COMPLETELY OUT OF THE QUESTION THAT A FEW WEAK
THUNDERSTORMS COULD MATERIALIZE ON A HIT AN MISS BASIS. WILL HOLD
OFF ON ANY THUNDER MENTION FOR NOW STILL BEING 5+ DAYS OUT...BUT
SOMETHING TO KEEP AN EYE ON. FOR NOW...WILL KEEP HIGH TEMPS FRIDAY
SIMILAR TO THURS WITH MID-UPPER 50S...BUT THE MEX GUIDANCE WOULD
SUGGEST IT COULD BE A BIT WARMER THAN THIS.
FINALLY FOR SATURDAY DAYTIME...CHANCES FOR RAIN SHOWERS CURRENTLY
APPEAR A BIT BETTER THAN PREVIOUS DAYS...AND THUS WILL GO WITH SOME
30 POPS BUT STILL KEEPING CHANCES FAIRLY LOW AT THIS TIME RANGE.
ESPECIALLY THE ECMWF SUGGESTS THAT A MODEST SHORTWAVE TROUGH COULD
DROP IN FROM THE NORTHWEST...AND PUSH A WEAK COLD FRONT THROUGH THE
REGION...PROVIDING A BIT MORE FORCING. AGAIN WILL HOLD OFF ON THE
INTRODUCTION OF THUNDERSTORMS AND JUST GO WITH SHOWER WORDING...BUT
THIS WILL BEAR WATCHING AS WEAK INSTABILITY COULD CERTAINLY BE IN
PLACE BY THEN. WILL AIM HIGH TEMPS IN THE 50S AGAIN...BUT DEPENDING
ON HOW TRENDS PLAY OUT WOULD NOT BE SURPRISED TO SEE SOME AREAS
CRACK 60.
&&
.AVIATION...(FOR THE 18Z TAF THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1258 PM CDT SUN MAR 24 2013
THIS AFTN: VFR WITH NW WINDS GUSTING TO 30 KTS AT TIMES. SCT
STRATOCU WILL CONTINUE TO FORM AND COULD RESULT IN A VFR CIG AFTER
21Z.
TNGT: VFR CIGS PROBABLY DEGRADE TO MVFR WITH SCT FLURRIES.
CONFIDENCE IS BELOW AVERAGE AND MVFR MAY NOT PREVAIL MUCH OF THE
TIME. WHILE THERE ARE MVFR CIGS UPSTREAM...THEY DEVELOPED WITH
DAYTIME HEATING AND ARE EXPECTED TO PARTIALLY DISSIPATE AFTER
SUNSET. INDICATED SOME LOWERING OF NW WINDS AND AN END TO THE
GUSTINESS...BUT WINDS COULD BE HIGHER THAN FCST IF THE WINDIER MET
MOS ENDS UP CORRECT.
MON THRU 18Z: MVFR CIGS MAY CONTINUE WITH OCCASIONAL FLURRIES.
AFTER 15Z NW WINDS GUST TO 25 KTS.
CIG CONFIDENCE: HIGH THRU 02Z THEN LOW UNTIL 18Z
VSBY CONFIDENCE: HIGH THRU 02Z THEN AVERAGE. LOW PROB 4SM SHSN
WIND CONFIDENCE: HIGH THRU 02Z THEN AVERAGE TNGT
WX CONFIDENCE: HIGH
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...HEINLEIN
LONG TERM...PFANNKUCH
AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1258 PM CDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 1258 PM CDT SUN MAR 24 2013
TEMPS/DWPTS IN GOOD SHAPE. MADE SOME MINOR ADJUSTMENTS TO CLOUDS.
VIS SATL SHOWS WIDESPREAD STRATOCU DEVELOPING BETWEEN LBF-TIF AND
HEADING FOR LXN. LNX 88D AND A CALL FROM LBF INDICATES FLURRIES.
SO FLURRIES HAVE RETURNED TO THE FCST FOR THIS AFTN. STRATOCU ARE
STRUGGLING TO FORM OVER MUCH OF THE FCST AREA. SO HIGHEST
CONFIDENCE IS W OF HWY 183. FCST SKY COVER THIS AFTER MAY NEED TO
BE LOWERED E OF HWY 183.
UPDATE ISSUED AT 932 CDT SUN MAR 24 2013
CYCLOGENESIS IS UNDERWAY OVER THE MID MS VALLEY. A SHRTWV RIDGE IS
OVER THE FCST AREA IN ITS WAKE AND HAS RESULTED IN CLEARING. 12Z
SOUNDINGS SHOW EXTENSIVE MSTR ALL THE WAY BACK TO MT/ND. SO EXPECT
DIURNAL STRATOCU TO DEVELOP AROUND MIDDAY.
THE BACK EDGE OF THE CIRRUS CANOPY WITH THE MID MS VALLEY LOW WAS
EXITING OUR ERN COUNTIES ALONG HWY 81. THESE AREAS WILL BECOME SUNNY
BY 11 AM.
VIS SATELLITE ALSO SHOW SOME MID-HIGH CLOUDS OVER WY AND NRN CO.
THESE CLOUDS WILL ALSO DIVE SE INTO THE FCST AREA. SO OVERALL EXPECT
A SUNNY MRNG TO TURN P/CLOUDY THIS AFTN.
DID MAKE SOME SUBSTANTIAL ADJUSTMENTS TO SKY FCST FORENOON TO ACCT
FOR CLEARING. WILL CONT TO MONITOR TEMP CURVES.
IT/S COLD! THE CAMBRIDGE CO-OP OBSERVER HAD A LOW TEMP OF 9F. AN
NDOR MESONET SITE IN ARAPAHOE ALSO REPORTED 9F. WIND CHILLS ARE
MOSTLY IN THE SINGLE DIGITS ACROSS THE FCST AREA.
OVERALL A BLUSTERY COLD DAY. 06Z NAM/11Z RAP BUFKIT TIME SECTIONS
SUGGEST PEAK WINDS AVAILABLE FOR MIXING ARE 30-33 KTS. SO NW WINDS
WILL GUST 25-35 MPH...THO LESS FREQUENTLY IN THE 30-35 MPH RANGE.
OTHER THAN SHORT-TERM SKY ALL OTHER FCST ELEMENTS LOOK GOOD.
ANALOGS: LOOKING BACK AT THE FCST ANALOG YEARS FROM 10 DAYS AGO...
THEY HAD A GREAT SIGNAL FOR THIS CURRENT STRETCH OF UNSEASONABLY
COLD MARCH WX. THOSE INCLUDED 1951 52 57 58 62 AND 2006.
UPDATE ISSUED AT 543 AM CDT SUN MAR 24 2013
UPDATED THE FORECAST FOR TODAY TO MAKE MINOR ADJUSTMENTS TO HOURLY
TEMPERATURES...WINDS...AND DEWPOINTS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 509 AM CDT SUN MAR 24 2013
THE MAIN CHALLENGE WILL BE DETERMINING CHANCES FOR FLURRIES/SNOW
SHOWERS TODAY AND TONIGHT.
UPPER LEVEL JET STREAM HAS MADE A DIVE WELL SOUTH OF THE AREA WITH A
RATHER LARGE LONGWAVE TROUGH OVER THE CENTRAL UNITED STATES. THIS
SHOULD ENSURE THAT WE REMAIN WELL BELOW NORMAL TODAY. AT
MID-LEVELS...A SOMEWHAT COMPLEX SCENARIO IS TAKING PLACE. A SET OF
DUMBBELL CLOSED LOWS OCCUPY THE AFOREMENTIONED LONGWAVE
TROUGH...WITH ONE OF THE LOWS TRACKING TO THE EAST ACROSS
SOUTHEASTERN KANSAS. THE SECOND LOW IS LOCATED OVER NORTH DAKOTA.
FOR TODAY...WE SHOULD BE IN AN AREA BETWEEN THE TWO CLOSED
LOW...WITH SOME SHORTWAVE RIDGING. THIS SHOULD KEEP FLURRIES/SNOW
SHOWERS OUT OF THE AREA DURING THE DAY TODAY...AND PERHAPS ALLOW A
PEAK OR TWO AT SOME SUN. WITH 850 MB TEMPERATURES RATHER SIMILAR TO
SATURDAY...AND WITH THE BIT OF CHANCE AT A PEAK OR TWO OF LATE MARCH
SUN...I HAVE BUMPED UP TEMPERATURES A BIT FOR TODAY.
THE APPROACHING CLOSED LOW IS EXPECTED TO FILL TODAY AS IT HEADS
SOUTH. THE LEFTOVER LOBE OF ENERGY WILL ARRIVE THIS EVENING AND
COULD SPAWN MORE FLURRIES/SNOW SHOWERS...WITH BETTER CHANCES TO THE
EAST/NORTHEAST...WITH THE BEST LARGE SCALE TO THE EAST/NORTHEAST. I
WENT WITH SIMILAR LOW TEMPERATURES TONIGHT COMPARED TO THE PREVIOUS
FORECAST WITH ONLY MINOR ADJUSTMENTS. BUMPED UP WIND SPEEDS JUST A
BIT WITH INCREASING LOW-LEVEL LAPSE RATES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 509 AM CDT SUN MAR 24 2013
THIS 6-DAY PERIOD WILL BE HIGHLIGHTED BY WHAT CURRENTLY APPEARS TO
BE A FEW LOW-END CHANCES FOR GENERALLY LIGHT MEASURABLE PRECIP...BUT
MORE IMPORTANTLY TO MANY FOLKS...A LEGITIMATE WARMING TREND BACK
INTO THE 40S AND AT LEAST 50S.
CERTAINLY MONDAY THROUGH TUESDAY THE AREA WILL STILL BE MIRED IN THE
MUCH-BELOW NORMAL COLD AIR. STARTING OFF SUNRISE MONDAY
MORNING...00Z/06Z MODELS SUCH AS THE NAM/GFS/ECMWF ARE IN GOOD
AGREEMENT DEPICTING AN ELONGATED MID LEVEL TROUGH EXTENDING FROM
NORTHWEST-SOUTHEAST ACROSS THE CENTRAL PLAINS...WHICH THEN GRADUALLY
DEPARTS TO THE SOUTHEAST DURING THE DAY...FEEDING INTO THE ENTRANCE
REGION OF A STOUT UPPER LEVEL JET STREAK ACROSS THE SOUTHEAST CONUS.
AT THE SURFACE MONDAY...ALTHOUGH A GRADUAL DECREASE IN WIND SPEEDS
WILL OCCUR DURING THE DAY...THE COMBINATION OF DEEP MIXING AND A
STILL TIGHTENED PRESSURE GRADIENT WILL RESULT IN FAIRLY BREEZY
CONDITIONS WITH SUSTAINED NORTHWEST WINDS AT LEAST 20 MPH GUSTING
25-30 MPH. THESE WINDS WILL RESULT IN ANOTHER VERY COLD DAY FOR LATE
MARCH...WITH WIND CHILL READINGS DURING THE AFTERNOON STRUGGLING TO
REACH THE LOW 20S. ACTUAL AIR TEMPERATURES WILL BE VERY SIMILAR TO
THOSE OF TODAY...WITH LOW TO POSSIBLY MID 30S CWA-WIDE.
PRECIPITATION-WISE...AS NOTED BY THE PAST SEVERAL FORECAST
SHIFTS...THIS IS A FAIRLY CLASSIC SETUP FOR AT LEAST A SLIGHT CHANCE
OF FLURRIES...AS FORCING FROM THE OVERHEAD ELONGATED SHORTWAVE
COMBINES WITH FAVORABLE DENDRITIC TEMPERATURES AROUND -11C IN A LOW
STRATUS LAYER TO SQUEEZE OUT SOME FLAKES. AS NOTED BY PREVIOUS DAY
SHIFT...PARTS OF THE EASTERN CWA COULD EVEN SEE SOME VERY LIGHT
MEASURABLE SNOW OF MAYBE A TENTH OF AN INCH OR TWO...AS SUGGESTED BY
LIGHT QPF EVIDENT IN VARIOUS MODEL FIELDS. AS A RESULT...MAINTAINED
A FLURRY CHANCE IN THE WEST THROUGH THE DAY...BUT ACTUALLY BEEFED UP
ROUGHLY THE NORTHEAST 1/2 OF THE CWA TO A 20 TO 30 PERCENT CHANCE OF
MEASURABLE LIGHT SNOW. THIS SHOULDN/T BE ANY KIND OF IMPACTFUL
SNOW...BUT FELT IT WAS WORTHY OF A SMALL POP AS SOME AREAS COULD SEE
A BIT MORE THAN FLURRIES. BY SUNSET MONDAY NIGHT...THE
AFOREMENTIONED MID LEVEL WAVE WILL BE JUST DEPARTING THE SOUTHERN
END OF THE CWA...AND ALTHOUGH SOME DEGREE OF LOW STRATUS COULD
LINGER THROUGH THE NIGHT...FEEL THE RISK OF LINGERING FLURRIES/LIGHT
SNOW IS LOW ENOUGH BY THEN TO END THE MENTION. TEMP-WISE...ITS VERY
POSSIBLE THAT MONDAY NIGHT COULD IN FACT BE THE COLDEST NIGHT FOR
THE NEXT SEVERAL MONTHS...AS A SURFACE RIDGE AXIS SETTLES IN AND
BREEZES BECOME VERY LIGHT BY SUNRISE. ALTHOUGH LINGERING CLOUDS
COULD WORK AGAINST A MAJOR DROP-OFF...WILL STILL CALL FOR MOST OF
THE CWA SETTLING DOWN TO AT LEAST 14-18 DEGREES. DESPITE THE LIGHT
WINDS...AM NOT OVERLY CONCERNED ABOUT IMPACTFUL FOG DEVELOPMENT...SO
WILL CONTINUE TO OMIT FROM THE FORECAST.
TUESDAY/TUESDAY NIGHT...CONFIDENCE IS RATHER HIGH IN A PRECIP-FREE
24 HOURS...ALTHOUGH WILL ACKNOWLEDGE THAT THE ECMWF CONTINUES TO
SPIT OUT SOME VERY LIGHT QPF NEAR THE SOUTHWEST EDGE OF THE CWA LATE
TUES NIGHT...LIKELY IN RESPONSE TO A MODEST BELT OF LOW-MID LEVEL
THETA-E ADVECTION AS A VERY SUBTLE MID LEVEL SHORTWAVE TROUGH
RIPPLES THROUGH WEST-NORTHWEST FLOW ALOFT. THE THINKING FOR NOW IS
THAT FAIRLY DRY LOW LEVELS WILL WORK AGAINST PRECIP
DEVELOPING...ESPECIALLY OF THE MEASURABLE VARIETY. HOWEVER...IT WILL
BEAR WATCHING AS TEMPERATURE PROFILES WOULD SUGGEST A LOW-END RISK
OF LIGHT FREEZING RAIN IF SOMETHING WERE TO MOVE IN. FOR NOW WILL
LEAVE TUES NIGHT PRECIP FREE THOUGH. BACKING UP TO THE TUESDAY
DAYTIME HOURS...DEVELOPING SOUTHERLY BREEZES SHOULD MARK THE
BEGINNING STAGES OF A NICE WARM-UP...AND NUDGED UP HIGH TEMPS A BIT
GETTING NEARLY ALL AREAS INTO THE LOW OR MID 40S.
WEDNESDAY/WEDNESDAY NIGHT...HAVE MAINTAINED A DRY
FORECAST...ALTHOUGH ITS NOT NECESSARILY A GUARANTEE TO STAY THAT WAY
AS BOTH THE ECMWF/GFS CONTINUE TO BRING A SERIES OF WEAK SHORTWAVES
THROUGH THE PERSISTENT WEST-NORTHWEST FLOW...WHICH COULD SATURATE
THE MID LEVELS JUST ENOUGH TO PRODUCE SOME SPRINKLES OR LIGHT RAIN.
AGAIN...CONFIDENCE JUST ISN/T HIGH ENOUGH TO GO THERE YET.
TEMP-WISE...THE WARM-UP CONTINUES WITH ALL NEBRASKA ZONES AIMED WELL
INTO THE MID-UPPER 40S AND EVEN SOME 50S NEAR/SOUTH OF THE STATE
LINE.
THURSDAY/THURSDAY NIGHT...BROAD WEST-NORTHWEST FLOW JUST KEEPS ON
PERSISTING OVER THE CENTRAL PLAINS...WITH EVEN A HINT OF HEIGHT
RISES AS A RIDGE BUILDS EASTWARD A BIT FROM THE ROCKIES. ALTHOUGH
ODDS ARE REASONABLY HIGH THAT THIS 24 HOURS WILL REMAIN
DRY...ESPECIALLY THE DAYTIME...WILL CONTINUE TO HANG ONTO A SLIGHT
CHANCE OF RAIN THURSDAY NIGHT FROM THE PREVIOUS FORECAST...ALTHOUGH
THIS CHANCE MAY VERY WELL BE DROPPED IN THE COMING DAYS. CONTINUED
MODIFICATION OF THE LOW LEVEL TEMPERATURE FIELDS RAISES CONFIDENCE
IN WIDESPREAD 50S FOR THURSDAY...WHICH WOULD MARK THE FIRST TIME IN
9-13 DAYS THAT MOST OF THE CWA HAS CRACKED 50.
FRIDAY/FRIDAY NIGHT...THE CWA-WIDE SLIGHT CHANCES OF RAIN SHOWERS
WERE MAINTAINED FROM THE PREVIOUS FORECAST...BUT AGAIN ITS BY NO
MEANS LOOKING LIKE A WIDESPREAD MEASURABLE RAIN RISK. THAT BEING
SAID...GRADUAL MOISTENING OF THE LOW LEVELS EVIDENT AT 850 MILLIBARS
COULD ACTUALLY GENERATE SOME WEAK INSTABILITY BY THIS TIME...AND
THUS ITS NOT COMPLETELY OUT OF THE QUESTION THAT A FEW WEAK
THUNDERSTORMS COULD MATERIALIZE ON A HIT AN MISS BASIS. WILL HOLD
OFF ON ANY THUNDER MENTION FOR NOW STILL BEING 5+ DAYS OUT...BUT
SOMETHING TO KEEP AN EYE ON. FOR NOW...WILL KEEP HIGH TEMPS FRIDAY
SIMILAR TO THURS WITH MID-UPPER 50S...BUT THE MEX GUIDANCE WOULD
SUGGEST IT COULD BE A BIT WARMER THAN THIS.
FINALLY FOR SATURDAY DAYTIME...CHANCES FOR RAIN SHOWERS CURRENTLY
APPEAR A BIT BETTER THAN PREVIOUS DAYS...AND THUS WILL GO WITH SOME
30 POPS BUT STILL KEEPING CHANCES FAIRLY LOW AT THIS TIME RANGE.
ESPECIALLY THE ECMWF SUGGESTS THAT A MODEST SHORTWAVE TROUGH COULD
DROP IN FROM THE NORTHWEST...AND PUSH A WEAK COLD FRONT THROUGH THE
REGION...PROVIDING A BIT MORE FORCING. AGAIN WILL HOLD OFF ON THE
INTRODUCTION OF THUNDERSTORMS AND JUST GO WITH SHOWER WORDING...BUT
THIS WILL BEAR WATCHING AS WEAK INSTABILITY COULD CERTAINLY BE IN
PLACE BY THEN. WILL AIM HIGH TEMPS IN THE 50S AGAIN...BUT DEPENDING
ON HOW TRENDS PLAY OUT WOULD NOT BE SURPRISED TO SEE SOME AREAS
CRACK 60.
&&
.AVIATION...(FOR THE 18Z TAF THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1258 PM CDT SUN MAR 24 2013
THIS AFTN: VFR WITH NW WINDS GUSTING TO 30 KTS AT TIMES. SCT
STRATOCU WILL CONTINUE TO FORM AND COULD RESULT IN A VFR CIG AFTER
21Z.
TNGT: VFR CIGS PROBABLY DEGRADE TO MVFR WITH SCT FLURRIES.
CONFIDENCE IS BELOW AVERAGE AND MVFR MAY NOT PREVAIL MUCH OF THE
TIME. WHILE THERE ARE MVFR CIGS UPSTREAM...THEY DEVELOPED WITH
DAYTIME HEATING AND ARE EXPECTED TO PARTIALLY DISSIPATE AFTER
SUNSET. INDICATED SOME LOWERING OF NW WINDS AND AN END TO THE
GUSTINESS...BUT WINDS COULD BE HIGHER THAN FCST IF THE WINDIER MET
MOS ENDS UP CORRECT.
MON THRU 18Z: MVFR CIGS MAY CONTINUE WITH OCCASIONAL FLURRIES.
AFTER 15Z NW WINDS GUST TO 25 KTS.
CIG CONFIDENCE: HIGH THRU 02Z THEN LOW UNTIL 18Z
VSBY CONFIDENCE: HIGH THRU 02Z THEN AVERAGE. LOW PROB 4SM SHSN
WIND CONFIDENCE: HIGH THRU 02Z THEN AVERAGE TNGT
WX CONFIDENCE: HIGH
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...HEINLEIN
LONG TERM...PFANNKUCH
AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
323 PM EDT SUN MAR 24 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER THE MISSISSIPPI RIVER VALLEY WILL MOVE
NORTHEAST INTO THE OHIO VALLEY TONIGHT. A SECOND AREA OF LOW
PRESSURE WILL DEVELOP NEAR CAPE FEAR THIS AFTERNOON AND MOVE SLOWLY
UP THE COAST TO NEAR NEW JERSEY BY MONDAY AFTERNOON. A COOL
NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
AS OF 300 PM SUNDAY...
THROUGH TONIGHT:
THE SURFACE LOW THAT DEVELOPED OVER THE SOUTHERN MISSISSIPPI RIVER
VALLEY OVERNIGHT HAS SPLIT INTO TWO SEPARATE LOWS...WITH ONE
DEEPENING AS IT MOVES NORTHEAST ALONG THE WEST SIDE OF THE
APPALACHIANS...AND THE SECOND MOVING OFF THE SE ATLANTIC COAST. AS
THE LOW CONTINUES TO MOVE OFF AND ALONG THE ATLANTIC COAST...UPPER
LEVEL WINDS SHOULD BRIEFLY BACK AROUND TO MORE SOUTHEASTERLY BEFORE
THE PARENT LOW OVER THE OHIO RIVER VALLEY MOVES EAST THROUGH THE MID
ATLANTIC. THE HRRR AND THE HIRES WRF-ARW CONVECTION ALLOWING
MODELS...WHICH ARE CAPTURING THE CURRENT REFLECTIVITIES BEST...
INDICATE AN AREA OF SHOWERS DEVELOPING AHEAD OF THE COLD FRONT
TONIGHT. AS SUCH...CONTINUE GRADUALLY DECREASING PRECIP CHANCES
ACROSS THE SOUTH AND EAST THIS AFTERNOON AND FROM WEST TO EAST
ACROSS THE AREA BEHIND THE FRONT OVERNIGHT. HPC GUIDANCE RAINFALL
AMOUNTS APPEAR TO BE A BIT OVERDONE. THUS HAVE GONE MORE TOWARD THE
TREND OF THE HRRR...GIVEN THE DRY SLOT MOVING INTO THE WEST AND THE
FORECAST REFLECTIVITIES FROM THE CONVECTION ALLOWING MODELS. WITH
THE HYBRID COLD AIR DAMMING EVENT LINGERING INTO TONIGHT...WILL SEE
NEAR STEADY TEMPS SLOWLY FALL AFTER SUNSET INTO THE LOW 30S NORTH TO
MID 30S SOUTH AND EAST BY DAYBREAK. THERE IS STILL SOME CONCERN THAT
THE BOUNDARY LAYER MAY COOL ENOUGH TO REACH FREEZING MONDAY MORNING
IN THE TRIAD AREA WHICH COULD RESULT IN SOME BLACK ICE. CONFIDENCE
IN THIS OCCURRING IS STILL LOW AT THIS TIME GIVEN THAT BOUNDARY
LAYER WINDS SHOULD STAY UP AROUND 5 KTS OR SO OVERNIGHT...WHICH WILL
LIMIT SURFACE COOLING AND MAY DRY THINGS OUT ENOUGH TO MITIGATE ANY
BLACK ICE FORMATION. ALSO...IT APPEARS THAT SKIES SHOULD REMAIN
CLOUDY THROUGH DAYBREAK...LIMITING RADIATIONAL COOLING.
MONDAY AND MONDAY NIGHT:
EXPECT THE LOW ALONG THE ATLANTIC COAST TO MERGE WITH THE INLAND LOW
MOVING EAST ACROSS THE MID ATLANTIC ON MONDAY...WITH LINGERING
CHANCES FOR SOME LIGHT RAINFALL/SPRINKLES ACROSS THE NORTH...MAINLY
IN THE AFTERNOON. WITH WINDS BACKING BEHIND THE FRONT AND COLDER AIR
ADVECTING INTO CENTRAL NC...EXPECT HIGH TEMPS IN THE MID TO UPPER
40S NORTH TO MID 50S ACROSS THE SOUTH. WINDS WILL BE STRONG AND
GUSTY OUT OF THE WNW ON MONDAY AND INTO MONDAY NIGHT...EXPECTING
SUSTAINED AT 15-20 KTS...GUSTING TO AROUND 30 KTS. MONDAY NIGHT LOWS
IN THE LOW TO MID 30S...WITH SOME OF THE OUTLYING AREAS POTENTIALLY
DIPPING INTO THE UPPER 20S.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 315 PM SUNDAY...
THE PATTERN ALOFT WILL CHANGE LITTLE - ANOTHER MID-UPPER
LOW...ANOTHER DAY. THIS ONE...CENTERED OVER THE NORTHERN PLAINS THIS
AFTERNOON...WILL SHEAR EASTWARD ACROSS THE SOUTHERN APPALACHIANS AND
NC DURING THE DAY TUE - ON A FAVORABLE TRACK FOR A LITTLE LIGHT
PRECIPITATION FOR CENTRAL NC. DESPITE THE FAVORABLE TRACK AND
ASSOCIATED DYNAMICS...PROJECTED THERMODYNAMICS...AS CHARACTERIZED BY
MID LEVEL (H85-5) LAPSE RATES OF ONLY AROUND 5.5 C/KM...HAVE TRENDED
MUCH WEAKER. NONETHELESS...RELATIVELY DEEP MIXED PHASE SATURATION
BETWEEN 5 AND 15 THOUSAND FT AMIDST POCKETS OF WEAK INSTABILITY ON
THE ORDER OF AROUND 100 OR SO J/KG...SHOULD SUPPORT THE DEVELOPMENT
OF DIURNALLY-ENHANCED SCATTERED SHOWERS...OR SPRINKLES OWING TO A
DRY ADIABATIC...4 THOUSAND FT SUB-CLOUD LAYER. WILL ACCORDINGLY
RETAIN THE SLIGHT TO LOW CHANCE PROBABILITY OF A FEW HUNDREDTHS OF
AN INCH LIQUID...WITH THE LOWEST CHANCES ACROSS THE SOUTHERN
PIEDMONT WHERE THE DEPTH OF THE MOISTURE IS FORECAST TO BE
SHALLOWER/WARMER. IF PRECIPITATION WERE TO OCCUR BEFORE 10-11
AM...WHICH IS UNLIKELY GIVEN THE ABSENCE OF DIURNALLY-DRIVEN WEAK
INSTABILITY BEFORE THAT TIME...THERE WOULD BE THE POTENTIAL FOR A
LITTLE SNOW MIXED WITH THE RAIN OVER THE WESTERN PIEDMONT.
REGARDLESS...NO IMPACT WOULD OCCUR GIVEN THE MARCH SUN ANGLE...AND
TEMPERATURES "WARMING" INTO THE MIDDLE 40S NORTH TO LOWER 50S
SOUTH...BENEATH A CLOUDY OR MOSTLY SO SKY. CLEARING AND COLD TUE
NIGHT...WITH LOWS IN THE UPPER 20S TO LOWER 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 255 PM SUNDAY...
NORTHWEST FLOW AND SLOWLY RISING HEIGHTS ALOFT...AS THE EASTERN
CONUS TROUGH GRADUALLY RELAXES...WILL RULE THROUGH THE MEDIUM RANGE.
BOTH CLIMATOLOGY AND NWP GUIDANCE SUGGEST THIS PERIOD WILL
CONSEQUENTLY BE DRY...AND COOLER THAN AVERAGE...THOUGH TRENDING BACK
INTO THE 60S SUN. THE CHILLIEST TEMPERATURES WILL BE THU AND FRI
NIGHTS AS THE SURFACE RIDGE DRIFTS OVERHEAD...WITH COOLEST READINGS
IN THE MID-UPPER 20S OVER THE WESTERN PIEDMONT FRI MORNING. IT STILL
APPEARS THE GULF OF MEXICO WILL BE BRIEFLY OPEN AHEAD OF A S/W
TROUGH AMPLIFYING THROUGH THE GREAT LAKES THIS WEEKEND...BUT
TIMING...AND DEGREE OF MOISTURE EAST OF THE MOUNTAINS AMIDST DEEP
LAYER WNW FLOW...REMAINS UNCERTAIN. AS SUCH...THE FORECAST WILL
BE KEPT DRY DURING THE WEEKEND.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 222 PM SUNDAY...
24 HOUR TAF PERIOD:
HIGH CONFIDENCE THAT LOW END MVFR TO IFR CIGS AND VISBYS WILL
CONTINUE INTO THE OVERNIGHT HOURS AS RAIN CONTINUES TO FALL. SHOULD
SEE A BREAK IN THE RAINFALL FROM SW TO NW LATE THIS AFTERNOON...
HOWEVER THERE WILL BE LITTLE...IF ANY...IMPROVEMENT IN AVIATION
CONDITIONS DURING THIS TIME. ANOTHER ROUND OF RAINFALL...THIS TIME
MORE SHOWERY IN NATURE...WILL MOVE THROUGH FROM WEST TO EAST AHEAD
OF A COLD FRONT OVERNIGHT. AS THE FRONT MOVES THROUGH IT WILL SCOUR
OUT THE LOW CLOUDS AND CEILINGS YIELDING IMPROVING AVIATION
CONDITIONS AFTER DAYBREAK. WILL SEE A DECREASE IN WINDS OVERNIGHT AS
THE THEY BACK FROM NE TO NW. THEREAFTER...LOW END VFR CONDITIONS
SHOULD PREVAIL THROUGH THE END OF THE TAF PERIOD...WITH THE MAIN
CONCERN LATE MONDAY MORNING TO EARLY MONDAY AFTERNOON BEING STRONG
GUSTY WINDS...MAINLY OUT OF THE WEST/NORTHWEST.
LOOKING AHEAD:
CONDITIONS THROUGH TUESDAY WEDNESDAY WILL BE SOMEWHAT UNSETTLED AND
THE CHANCE FOR A RAIN OR SNOW SHOWER ACROSS THE NORTH ON MONDAY AND
TUESDAY WITH A DECREASE IN CIGS CANNOT BE COMPLETELY RULED OUT.
OTHERWISE...EXPECT MAINLY BROKEN TO OVERCAST VFR CONDITIONS THROUGH
WEDNESDAY...WITH DECREASING CLOUDS THEREAFTER.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...KC
SHORT TERM...MWS
LONG TERM...MWS
AVIATION...KC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
303 PM EDT SUN MAR 24 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER THE MISSISSIPPI RIVER VALLEY WILL MOVE
NORTHEAST INTO THE OHIO VALLEY TONIGHT. A SECOND AREA OF LOW
PRESSURE WILL DEVELOP NEAR CAPE FEAR THIS AFTERNOON AND MOVE SLOWLY
UP THE COAST TO NEAR NEW JERSEY BY MONDAY AFTERNOON. A COOL
NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
AS OF 300 PM SUNDAY...
THROUGH TONIGHT:
THE SURFACE LOW THAT DEVELOPED OVER THE SOUTHERN MISSISSIPPI RIVER
VALLEY OVERNIGHT HAS SPLIT INTO TWO SEPARATE LOWS...WITH ONE
DEEPENING AS IT MOVES NORTHEAST ALONG THE WEST SIDE OF THE
APPALACHIANS...AND THE SECOND MOVING OFF THE SE ATLANTIC COAST. AS
THE LOW CONTINUES TO MOVE OFF AND ALONG THE ATLANTIC COAST...UPPER
LEVEL WINDS SHOULD BRIEFLY BACK AROUND TO MORE SOUTHEASTERLY BEFORE
THE PARENT LOW OVER THE OHIO RIVER VALLEY MOVES EAST THROUGH THE MID
ATLANTIC. THE HRRR AND THE HIRES WRF-ARW CONVECTION ALLOWING
MODELS...WHICH ARE CAPTURING THE CURRENT REFLECTIVITIES BEST...
INDICATE AN AREA OF SHOWERS DEVELOPING AHEAD OF THE COLD FRONT
TONIGHT. AS SUCH...CONTINUE GRADUALLY DECREASING PRECIP CHANCES
ACROSS THE SOUTH AND EAST THIS AFTERNOON AND FROM WEST TO EAST
ACROSS THE AREA BEHIND THE FRONT OVERNIGHT. HPC GUIDANCE RAINFALL
AMOUNTS APPEAR TO BE A BIT OVERDONE. THUS HAVE GONE MORE TOWARD THE
TREND OF THE HRRR...GIVEN THE DRY SLOT MOVING INTO THE WEST AND THE
FORECAST REFLECTIVITIES FROM THE CONVECTION ALLOWING MODELS. WITH
THE HYBRID COLD AIR DAMMING EVENT LINGERING INTO TONIGHT...WILL SEE
NEAR STEADY TEMPS SLOWLY FALL AFTER SUNSET INTO THE LOW 30S NORTH TO
MID 30S SOUTH AND EAST BY DAYBREAK. THERE IS STILL SOME CONCERN THAT
THE BOUNDARY LAYER MAY COOL ENOUGH TO REACH FREEZING MONDAY MORNING
IN THE TRIAD AREA WHICH COULD RESULT IN SOME BLACK ICE. CONFIDENCE
IN THIS OCCURRING IS STILL LOW AT THIS TIME GIVEN THAT BOUNDARY
LAYER WINDS SHOULD STAY UP AROUND 5 KTS OR SO OVERNIGHT...WHICH WILL
LIMIT SURFACE COOLING AND MAY DRY THINGS OUT ENOUGH TO MITIGATE ANY
BLACK ICE FORMATION. ALSO...IT APPEARS THAT SKIES SHOULD REMAIN
CLOUDY THROUGH DAYBREAK...LIMITING RADIATIONAL COOLING.
MONDAY AND MONDAY NIGHT:
EXPECT THE LOW ALONG THE ATLANTIC COAST TO MERGE WITH THE INLAND LOW
MOVING EAST ACROSS THE MID ATLANTIC ON MONDAY...WITH LINGERING
CHANCES FOR SOME LIGHT RAINFALL/SPRINKLES ACROSS THE NORTH...MAINLY
IN THE AFTERNOON. WITH WINDS BACKING BEHIND THE FRONT AND COLDER AIR
ADVECTING INTO CENTRAL NC...EXPECT HIGH TEMPS IN THE MID TO UPPER
40S NORTH TO MID 50S ACROSS THE SOUTH. WINDS WILL BE STRONG AND
GUSTY OUT OF THE WNW ON MONDAY AND INTO MONDAY NIGHT...EXPECTING
SUSTAINED AT 15-20 KTS...GUSTING TO AROUND 30 KTS. MONDAY NIGHT LOWS
IN THE LOW TO MID 30S...WITH SOME OF THE OUTLYING AREAS POTENTIALLY
DIPPING INTO THE UPPER 20S.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 315 AM SUNDAY...
THE AFOREMENTIONED STRONG MID/UPPER LEVEL PV ANOMALY WILL MOVE
THROUGH THE CAROLINAS ON A MORE SOUTHERN TRACK THAN THE INITIAL
UPPER LOW PASSAGE THE DAY BEFORE(MONDAY). THIS MORE SOUTHERN TRACK
WILL RESULT IN BETTER CHANCES OF SEEING SOME MEASURABLE PRECIP
ACROSS CENTRAL NC ON TUESDAY. NAM/GFS BUFR BUFKIT SOUNDINGS SHOW A
DECENT SIZE DENDRITIC GROWTH ZONE THAT IS ABOUT 75MB DEEP ACROSS THE
NORTHERN HALF OF THE FORECAST AREA THROUGH MIDDAY TUESDAY(~18Z).
IF THE PRECIP STARTS EARLY ENOUGH IN THE MORNING...NORTHERN PORTIONS
OF THE FORECAST AREA COULD DEFINITELY SEE A QUICK PASSING SNOW
SHOWER...WITH IT BECOMING INCREASING MIXED WITH RAIN LATER INTO THE
DAY AS TEMPERATURES IN THE SHALLOW ABOVE FREEZING LAYER
ONCE AGAIN WARM INTO THE MID-UPPER 40S...TO LOWER 50S SOUTH.
NO ACCUMULATIONS ARE EXPECTED.
CLOUDS WILL FINALLY CLEAR OUT TUESDAY NIGHT WITH PRESSURE GRADIENT
RELAXING AS WELL. LOWS IN THE UPPER 20S TO LOWER 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 255 PM SUNDAY...
NORTHWEST FLOW AND SLOWLY RISING HEIGHTS ALOFT...AS THE EASTERN
CONUS TROUGH GRADUALLY RELAXES...WILL RULE THROUGH THE MEDIUM RANGE.
BOTH CLIMATOLOGY AND NWP GUIDANCE SUGGEST THIS PERIOD WILL
CONSEQUENTLY BE DRY...AND COOLER THAN AVERAGE...THOUGH TRENDING BACK
INTO THE 60S SUN. THE CHILLIEST TEMPERATURES WILL BE THU AND FRI
NIGHTS AS THE SURFACE RIDGE DRIFTS OVERHEAD...WITH COOLEST READINGS
IN THE MID-UPPER 20S OVER THE WESTERN PIEDMONT FRI MORNING. IT STILL
APPEARS THE GULF OF MEXICO WILL BE BRIEFLY OPEN AHEAD OF A S/W
TROUGH AMPLIFYING THROUGH THE GREAT LAKES THIS WEEKEND...BUT
TIMING...AND DEGREE OF MOISTURE EAST OF THE MOUNTAINS AMIDST DEEP
LAYER WNW FLOW...REMAINS UNCERTAIN. AS SUCH...THE FORECAST WILL
BE KEPT DRY DURING THE WEEKEND.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 222 PM SUNDAY...
24 HOUR TAF PERIOD:
HIGH CONFIDENCE THAT LOW END MVFR TO IFR CIGS AND VISBYS WILL
CONTINUE INTO THE OVERNIGHT HOURS AS RAIN CONTINUES TO FALL. SHOULD
SEE A BREAK IN THE RAINFALL FROM SW TO NW LATE THIS AFTERNOON...
HOWEVER THERE WILL BE LITTLE...IF ANY...IMPROVEMENT IN AVIATION
CONDITIONS DURING THIS TIME. ANOTHER ROUND OF RAINFALL...THIS TIME
MORE SHOWERY IN NATURE...WILL MOVE THROUGH FROM WEST TO EAST AHEAD
OF A COLD FRONT OVERNIGHT. AS THE FRONT MOVES THROUGH IT WILL SCOUR
OUT THE LOW CLOUDS AND CEILINGS YIELDING IMPROVING AVIATION
CONDITIONS AFTER DAYBREAK. WILL SEE A DECREASE IN WINDS OVERNIGHT AS
THE THEY BACK FROM NE TO NW. THEREAFTER...LOW END VFR CONDITIONS
SHOULD PREVAIL THROUGH THE END OF THE TAF PERIOD...WITH THE MAIN
CONCERN LATE MONDAY MORNING TO EARLY MONDAY AFTERNOON BEING STRONG
GUSTY WINDS...MAINLY OUT OF THE WEST/NORTHWEST.
LOOKING AHEAD:
CONDITIONS THROUGH TUESDAY WEDNESDAY WILL BE SOMEWHAT UNSETTLED AND
THE CHANCE FOR A RAIN OR SNOW SHOWER ACROSS THE NORTH ON MONDAY AND
TUESDAY WITH A DECREASE IN CIGS CANNOT BE COMPLETELY RULED OUT.
OTHERWISE...EXPECT MAINLY BROKEN TO OVERCAST VFR CONDITIONS THROUGH
WEDNESDAY...WITH DECREASING CLOUDS THEREAFTER.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...KC
SHORT TERM...CBL
LONG TERM...MWS
AVIATION...KC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
258 PM EDT SUN MAR 24 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER THE MISSISSIPPI RIVER VALLEY WILL MOVE
NORTHEAST INTO THE OHIO VALLEY TONIGHT. A SECOND AREA OF LOW
PRESSURE WILL DEVELOP NEAR CAPE FEAR THIS AFTERNOON AND MOVE SLOWLY
UP THE COAST TO NEAR NEW JERSEY BY MONDAY AFTERNOON. A COOL
NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1100 AM SUNDAY...
TODAY:
THE SURFACE LOW THAT DEVELOPED OVER THE SOUTHERN MISSISSIPPI RIVER
VALLEY OVERNIGHT WILL CONTINUE TO SPLIT INTO TWO SEPARATE LOWS AS IT
MOVES NORTH AND EAST THIS MORNING. THE WESTERN MOST LOW WILL DEEPEN
AS IT MOVES NORTHEAST ALONG THE WEST SIDE OF THE APPALACHIANS...
WHILE THE SECOND WILL INTENSIFY OFF THE SE ATLANTIC COAST AND
MIGRATE NE ALONG IT. ALTHOUGH SOME LIGHT TO MODERATE RAIN HAS MOVED
INTO CENTRAL NC THIS MORNING...THE STRONGEST CONVECTION AND HEAVIEST
RAINFALL HAS REMAINED SOUTH OF THE AREA. 12Z UPPER AIR ANALYSES SHOW
THE H85 LOW ALREADY SPLITTING...WITH SOME INDICATION OF THE
SECONDARY LOW AT 700 MB. CENTRAL NC IS UNDER THE RIGHT REAR QUADRANT
OF THE 150+ KT UPPER LEVEL JET...WITH A SECOND JET...WITH WINDS JUST
UNDER 150 KTS...TO THE SOUTHEAST. WHILE SURFACE WINDS ARE MAINLY ENE
TO NE ACROSS THE AREA...UPPER LEVEL WINDS ARE SOUTH AND SW. AS THE
LOW MOVES OFF THE ATLANTIC COAST UPPER LEVEL WINDS SHOULD BRIEFLY
BACK AROUND TO MORE SOUTHEASTERLY BEFORE THE LOW...INITIALLY TO THE
WEST OF THE APPALACHIANS...MOVES EAST THROUGH THE MID ATLANTIC. THE
10Z HRRR AND THE 00Z HIRES WRF-ARW CONVECTION ALLOWING MODELS...
WHICH ARE CAPTURING THE CURRENT REFLECTIVITIES BEST...INDICATE AN
AREA OF LIGHT RAINFALL FILLING IN BEHIND THE BREAK...MAINLY ACROSS
THE NORTH AND NORTHWEST WITH SOME SHOWERS POSSIBLE THROUGH TONIGHT.
AS SUCH...CONTINUE WITH 100 PERCENT CHANCE FOR RAIN INTO THE
AFTERNOON WITH CHANCES GRADUALLY DECREASING ACROSS THE WEST AND
SOUTH THIS AFT/EVE. WHILE RAINFALL AMOUNTS ARE NOT ENTIRELY
CERTAIN...HPC GUIDANCE APPEARS TO BE A BIT OVERDONE. GIVEN THE DRY
SLOT MOVING INTO THE WEST AND THE FORECAST REFLECTIVITIES FROM THE
CONVECTION ALLOWING MODELS...WILL HAVE RAINFALL AMOUNTS LESS THAN
GUIDANCE...WITH HIGHEST TOTALS ACROSS THE NORTH. -KC
WITH THE HYBRID COLD AIR DAMMING EVENT TODAY AND TONIGHT...
TEMPERATURES WILL FEATURE VERY LITTLE DIURNAL RANGE...ESPECIALLY IN
THE HEART OF THE DAMMING REGION. HIGHS SHOULD RANGE IN THE UPPER 30S
IN THE NW PIEDMONT TO THE MID 40S IN THE SOUTHERN COASTAL PLAIN.
TEMPERATURES TONIGHT WILL FEATURE ONLY A MODEST DROP OFF WITH LOWS
TONIGHT WILL RANGING FROM THE LOWER/MID 30S ACROSS THE NORTHWEST TO
UPPER 30S SOUTHEAST. -BLAES
TONIGHT:
THE LAST BATCH OF SHOWERS...POSSIBLY INCLUDING SOME SHALLOW
CONVECTION WILL SWING EAST AND NORTHEAST THROUGH CENTRAL NC BETWEEN
02-08Z. WITH ANY LINGERING PRECIPITATION HUGGING THE VA BORDER OR
PERHAPS SOME PATCHY DRIZZLE. THERE IS SOME CONCERN THAT THE BOUNDARY
LAYER MAY COOL ENOUGH TO REACH FREEZING ON MONDAY MORNING IN THE
TRIAD AREA WHICH COULD RESULT IN SOME BLACK ICE. WHILE THE NEAR
SURFACE FLOW IS BECOMING SOUTHWEST/WEST AND DRYING...IT APPEARS THAT
SKIES SHOULD REMAIN CLOUDY THROUGH DAYBREAK LIMITING RADIATIONAL
COOLING. SUBSEQUENT SHIFTS WILL NEED TO MONITOR THE POTENTIAL FOR
SOME CLEARING AND A SUDDEN DROP IN SURFACE TEMPS AT DAYBREAK
ALTHOUGH THIS APPEARS UNLIKELY AS TURBULENT MIXING WILL LIKELY BE
ONGOING AND LIMIT SFC COOLING. -BLAES
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 315 AM SUNDAY...
MONDAY AND MONDAY NIGHT:
THE INLAND SFC LOW(OVER THE TN/OH VALLEY)ASSOCIATED WITH THE MILLER
B STORM SYSTEM WILL QUICKLY GIVE WAY TO THE RAPIDLY INTENSIFYING
SECONDARY LOW LIFTING NORTHWARD UP THE MID ATLC COAST MONDAY
MORNING. AS THE SYSTEM GAINS NORTHERN LATITUDE...THE RESULTANT
WEST-NWLY LOW-LEVEL FLOW WILL ADVECT COLDER-DRIER AIR INTO THE
AREA...SCOURING OUT THE RESIDUAL DAMMING AIRMASS LEADING TO PARTIAL
OR SHORT-LIVED CLEARING THROUGH THE FIRST HALF OF THE DAY ON MONDAY
BEFORE THE ARRIVAL OF THE UPPER LOW DYNAMICS BRINGS RENEW MID/UPPER
LEVEL LIFT MONDAY AFTERNOON. MOISTURE WILL BE LIMITED HOWEVER AND
WILL LIKELY SUPPORT ONLY SPRINKLES...AND QUITE POSSIBLY A WET FLAKE
OR TWO ACROSS NORTHERN PORTIONS OF THE FORECAST AREA MONDAY
AFTERNOON. HIGHS IN THE MID TO UPPER 40S NORTH TO LOWER 50S SOUTH
WITH BLUSTERY WESTERLY WINDS OF 20 MPH...GUSTING TO 30 MPH AT TIMES.
EXPECT A BRIEF LULL ACROSS CENTRAL NC IN THE WAKE OF THE UPPER LOW
EXITING OFF THE DELMARVA COAST MONDAY EVENING...BEFORE THE ARRIVAL
OF A STRONG MID/UPPER LEVEL PV ANOMALY INTO THE SOUTHERN APPALACHIANS
BY DAYBREAK TUESDAY. ANY PRECIP SHOULD HOLD OFF UNTIL DAYBREAK
TUESDAY SO WILL KEEP FORECAST DRY WHILE HOLDING ON TO AMPLE CLOUD
COVER. LOWS IN THE UPPER 20 TO LOWER 30S.
TUESDAY AND TUESDAY NIGHT:
THE AFOREMENTIONED STRONG MID/UPPER LEVEL PV ANOMALY WILL MOVE
THROUGH THE CAROLINAS ON A MORE SOUTHERN TRACK THAN THE INITIAL
UPPER LOW PASSAGE THE DAY BEFORE(MONDAY). THIS MORE SOUTHERN TRACK
WILL RESULT IN BETTER CHANCES OF SEEING SOME MEASURABLE PRECIP
ACROSS CENTRAL NC ON TUESDAY. NAM/GFS BUFR BUFKIT SOUNDINGS SHOW A
DECENT SIZE DENDRITIC GROWTH ZONE THAT IS ABOUT 75MB DEEP ACROSS THE
NORTHERN HALF OF THE FORECAST AREA THROUGH MIDDAY TUESDAY(~18Z).
IF THE PRECIP STARTS EARLY ENOUGH IN THE MORNING...NORTHERN PORTIONS
OF THE FORECAST AREA COULD DEFINITELY SEE A QUICK PASSING SNOW
SHOWER...WITH IT BECOMING INCREASING MIXED WITH RAIN LATER INTO THE
DAY AS TEMPERATURES IN THE SHALLOW ABOVE FREEZING LAYER
ONCE AGAIN WARM INTO THE MID-UPPER 40S...TO LOWER 50S SOUTH.
NO ACCUMULATIONS ARE EXPECTED.
CLOUDS WILL FINALLY CLEAR OUT TUESDAY NIGHT WITH PRESSURE GRADIENT
RELAXING AS WELL. LOWS IN THE UPPER 20S TO LOWER 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 255 PM SUNDAY...
NORTHWEST FLOW AND SLOWLY RISING HEIGHTS ALOFT...AS THE EASTERN
CONUS TROUGH GRADUALLY RELAXES...WILL RULE THROUGH THE MEDIUM RANGE.
BOTH CLIMATOLOGY AND NWP GUIDANCE SUGGEST THIS PERIOD WILL
CONSEQUENTLY BE DRY...AND COOLER THAN AVERAGE...THOUGH TRENDING BACK
INTO THE 60S SUN. THE CHILLIEST TEMPERATURES WILL BE THU AND FRI
NIGHTS AS THE SURFACE RIDGE DRIFTS OVERHEAD...WITH COOLEST READINGS
IN THE MID-UPPER 20S OVER THE WESTERN PIEDMONT FRI MORNING. IT STILL
APPEARS THE GULF OF MEXICO WILL BE BRIEFLY OPEN AHEAD OF A S/W
TROUGH AMPLIFYING THROUGH THE GREAT LAKES THIS WEEKEND...BUT
TIMING...AND DEGREE OF MOISTURE EAST OF THE MOUNTAINS AMIDST DEEP
LAYER WNW FLOW...REMAINS UNCERTAIN. AS SUCH...THE FORECAST WILL
BE KEPT DRY DURING THE WEEKEND.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 222 PM SUNDAY...
24 HOUR TAF PERIOD:
HIGH CONFIDENCE THAT LOW END MVFR TO IFR CIGS AND VISBYS WILL
CONTINUE INTO THE OVERNIGHT HOURS AS RAIN CONTINUES TO FALL. SHOULD
SEE A BREAK IN THE RAINFALL FROM SW TO NW LATE THIS AFTERNOON...
HOWEVER THERE WILL BE LITTLE...IF ANY...IMPROVEMENT IN AVIATION
CONDITIONS DURING THIS TIME. ANOTHER ROUND OF RAINFALL...THIS TIME
MORE SHOWERY IN NATURE...WILL MOVE THROUGH FROM WEST TO EAST AHEAD
OF A COLD FRONT OVERNIGHT. AS THE FRONT MOVES THROUGH IT WILL SCOUR
OUT THE LOW CLOUDS AND CEILINGS YIELDING IMPROVING AVIATION
CONDITIONS AFTER DAYBREAK. WILL SEE A DECREASE IN WINDS OVERNIGHT AS
THE THEY BACK FROM NE TO NW. THEREAFTER...LOW END VFR CONDITIONS
SHOULD PREVAIL THROUGH THE END OF THE TAF PERIOD...WITH THE MAIN
CONCERN LATE MONDAY MORNING TO EARLY MONDAY AFTERNOON BEING STRONG
GUSTY WINDS...MAINLY OUT OF THE WEST/NORTHWEST.
LOOKING AHEAD:
CONDITIONS THROUGH TUESDAY WEDNESDAY WILL BE SOMEWHAT UNSETTLED AND
THE CHANCE FOR A RAIN OR SNOW SHOWER ACROSS THE NORTH ON MONDAY AND
TUESDAY WITH A DECREASE IN CIGS CANNOT BE COMPLETELY RULED OUT.
OTHERWISE...EXPECT MAINLY BROKEN TO OVERCAST VFR CONDITIONS THROUGH
WEDNESDAY...WITH DECREASING CLOUDS THEREAFTER.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...KC/BLAES
SHORT TERM...CBL
LONG TERM...MWS
AVIATION...KC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
223 PM EDT SUN MAR 24 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER THE MISSISSIPPI RIVER VALLEY WILL MOVE
NORTHEAST INTO THE OHIO VALLEY TONIGHT. A SECOND AREA OF LOW
PRESSURE WILL DEVELOP NEAR CAPE FEAR THIS AFTERNOON AND MOVE SLOWLY
UP THE COAST TO NEAR NEW JERSEY BY MONDAY AFTERNOON. A COOL
NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1100 AM SUNDAY...
TODAY:
THE SURFACE LOW THAT DEVELOPED OVER THE SOUTHERN MISSISSIPPI RIVER
VALLEY OVERNIGHT WILL CONTINUE TO SPLIT INTO TWO SEPARATE LOWS AS IT
MOVES NORTH AND EAST THIS MORNING. THE WESTERN MOST LOW WILL DEEPEN
AS IT MOVES NORTHEAST ALONG THE WEST SIDE OF THE APPALACHIANS...
WHILE THE SECOND WILL INTENSIFY OFF THE SE ATLANTIC COAST AND
MIGRATE NE ALONG IT. ALTHOUGH SOME LIGHT TO MODERATE RAIN HAS MOVED
INTO CENTRAL NC THIS MORNING...THE STRONGEST CONVECTION AND HEAVIEST
RAINFALL HAS REMAINED SOUTH OF THE AREA. 12Z UPPER AIR ANALYSES SHOW
THE H85 LOW ALREADY SPLITTING...WITH SOME INDICATION OF THE
SECONDARY LOW AT 700 MB. CENTRAL NC IS UNDER THE RIGHT REAR QUADRANT
OF THE 150+ KT UPPER LEVEL JET...WITH A SECOND JET...WITH WINDS JUST
UNDER 150 KTS...TO THE SOUTHEAST. WHILE SURFACE WINDS ARE MAINLY ENE
TO NE ACROSS THE AREA...UPPER LEVEL WINDS ARE SOUTH AND SW. AS THE
LOW MOVES OFF THE ATLANTIC COAST UPPER LEVEL WINDS SHOULD BRIEFLY
BACK AROUND TO MORE SOUTHEASTERLY BEFORE THE LOW...INITIALLY TO THE
WEST OF THE APPALACHIANS...MOVES EAST THROUGH THE MID ATLANTIC. THE
10Z HRRR AND THE 00Z HIRES WRF-ARW CONVECTION ALLOWING MODELS...
WHICH ARE CAPTURING THE CURRENT REFLECTIVITIES BEST...INDICATE AN
AREA OF LIGHT RAINFALL FILLING IN BEHIND THE BREAK...MAINLY ACROSS
THE NORTH AND NORTHWEST WITH SOME SHOWERS POSSIBLE THROUGH TONIGHT.
AS SUCH...CONTINUE WITH 100 PERCENT CHANCE FOR RAIN INTO THE
AFTERNOON WITH CHANCES GRADUALLY DECREASING ACROSS THE WEST AND
SOUTH THIS AFT/EVE. WHILE RAINFALL AMOUNTS ARE NOT ENTIRELY
CERTAIN...HPC GUIDANCE APPEARS TO BE A BIT OVERDONE. GIVEN THE DRY
SLOT MOVING INTO THE WEST AND THE FORECAST REFLECTIVITIES FROM THE
CONVECTION ALLOWING MODELS...WILL HAVE RAINFALL AMOUNTS LESS THAN
GUIDANCE...WITH HIGHEST TOTALS ACROSS THE NORTH. -KC
WITH THE HYBRID COLD AIR DAMMING EVENT TODAY AND TONIGHT...
TEMPERATURES WILL FEATURE VERY LITTLE DIURNAL RANGE...ESPECIALLY IN
THE HEART OF THE DAMMING REGION. HIGHS SHOULD RANGE IN THE UPPER 30S
IN THE NW PIEDMONT TO THE MID 40S IN THE SOUTHERN COASTAL PLAIN.
TEMPERATURES TONIGHT WILL FEATURE ONLY A MODEST DROP OFF WITH LOWS
TONIGHT WILL RANGING FROM THE LOWER/MID 30S ACROSS THE NORTHWEST TO
UPPER 30S SOUTHEAST. -BLAES
TONIGHT:
THE LAST BATCH OF SHOWERS...POSSIBLY INCLUDING SOME SHALLOW
CONVECTION WILL SWING EAST AND NORTHEAST THROUGH CENTRAL NC BETWEEN
02-08Z. WITH ANY LINGERING PRECIPITATION HUGGING THE VA BORDER OR
PERHAPS SOME PATCHY DRIZZLE. THERE IS SOME CONCERN THAT THE BOUNDARY
LAYER MAY COOL ENOUGH TO REACH FREEZING ON MONDAY MORNING IN THE
TRIAD AREA WHICH COULD RESULT IN SOME BLACK ICE. WHILE THE NEAR
SURFACE FLOW IS BECOMING SOUTHWEST/WEST AND DRYING...IT APPEARS THAT
SKIES SHOULD REMAIN CLOUDY THROUGH DAYBREAK LIMITING RADIATIONAL
COOLING. SUBSEQUENT SHIFTS WILL NEED TO MONITOR THE POTENTIAL FOR
SOME CLEARING AND A SUDDEN DROP IN SURFACE TEMPS AT DAYBREAK
ALTHOUGH THIS APPEARS UNLIKELY AS TURBULENT MIXING WILL LIKELY BE
ONGOING AND LIMIT SFC COOLING. -BLAES
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 315 AM SUNDAY...
MONDAY AND MONDAY NIGHT:
THE INLAND SFC LOW(OVER THE TN/OH VALLEY)ASSOCIATED WITH THE MILLER
B STORM SYSTEM WILL QUICKLY GIVE WAY TO THE RAPIDLY INTENSIFYING
SECONDARY LOW LIFTING NORTHWARD UP THE MID ATLC COAST MONDAY
MORNING. AS THE SYSTEM GAINS NORTHERN LATITUDE...THE RESULTANT
WEST-NWLY LOW-LEVEL FLOW WILL ADVECT COLDER-DRIER AIR INTO THE
AREA...SCOURING OUT THE RESIDUAL DAMMING AIRMASS LEADING TO PARTIAL
OR SHORT-LIVED CLEARING THROUGH THE FIRST HALF OF THE DAY ON MONDAY
BEFORE THE ARRIVAL OF THE UPPER LOW DYNAMICS BRINGS RENEW MID/UPPER
LEVEL LIFT MONDAY AFTERNOON. MOISTURE WILL BE LIMITED HOWEVER AND
WILL LIKELY SUPPORT ONLY SPRINKLES...AND QUITE POSSIBLY A WET FLAKE
OR TWO ACROSS NORTHERN PORTIONS OF THE FORECAST AREA MONDAY
AFTERNOON. HIGHS IN THE MID TO UPPER 40S NORTH TO LOWER 50S SOUTH
WITH BLUSTERY WESTERLY WINDS OF 20 MPH...GUSTING TO 30 MPH AT TIMES.
EXPECT A BRIEF LULL ACROSS CENTRAL NC IN THE WAKE OF THE UPPER LOW
EXITING OFF THE DELMARVA COAST MONDAY EVENING...BEFORE THE ARRIVAL
OF A STRONG MID/UPPER LEVEL PV ANOMALY INTO THE SOUTHERN APPALACHIANS
BY DAYBREAK TUESDAY. ANY PRECIP SHOULD HOLD OFF UNTIL DAYBREAK
TUESDAY SO WILL KEEP FORECAST DRY WHILE HOLDING ON TO AMPLE CLOUD
COVER. LOWS IN THE UPPER 20 TO LOWER 30S.
TUESDAY AND TUESDAY NIGHT:
THE AFOREMENTIONED STRONG MID/UPPER LEVEL PV ANOMALY WILL MOVE
THROUGH THE CAROLINAS ON A MORE SOUTHERN TRACK THAN THE INITIAL
UPPER LOW PASSAGE THE DAY BEFORE(MONDAY). THIS MORE SOUTHERN TRACK
WILL RESULT IN BETTER CHANCES OF SEEING SOME MEASURABLE PRECIP
ACROSS CENTRAL NC ON TUESDAY. NAM/GFS BUFR BUFKIT SOUNDINGS SHOW A
DECENT SIZE DENDRITIC GROWTH ZONE THAT IS ABOUT 75MB DEEP ACROSS THE
NORTHERN HALF OF THE FORECAST AREA THROUGH MIDDAY TUESDAY(~18Z).
IF THE PRECIP STARTS EARLY ENOUGH IN THE MORNING...NORTHERN PORTIONS
OF THE FORECAST AREA COULD DEFINITELY SEE A QUICK PASSING SNOW
SHOWER...WITH IT BECOMING INCREASING MIXED WITH RAIN LATER INTO THE
DAY AS TEMPERATURES IN THE SHALLOW ABOVE FREEZING LAYER
ONCE AGAIN WARM INTO THE MID-UPPER 40S...TO LOWER 50S SOUTH.
NO ACCUMULATIONS ARE EXPECTED.
CLOUDS WILL FINALLY CLEAR OUT TUESDAY NIGHT WITH PRESSURE GRADIENT
RELAXING AS WELL. LOWS IN THE UPPER 20S TO LOWER 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 315 AM SUNDAY...
WITH THE HIGH-LATITUDE BLOCK REMAINING IN PLACE...TEMPERATURES WILL
BE VERY SLOW TO MODERATE UNDERNEATH THE NEGATIVE HEIGHT ANOMALIES
ANCHORED ALONG THE EASTERN CONUS/WESTERN ATLANTIC. THUS...COOL-BELOW
NORMAL TEMPERATURES WILL CONTINUE THROUGH THE END OF THE WORK
WEEK...WITH AT OR BELOW FREEZING MINS EACH NIGHT. AS HEIGHTS BEGIN
TO INCREASE ALOFT AND THE CANADIAN SFC HIGH SHIFTS EAST OF THE
AREA...DAYTIME TEMPERATURES WILL LOOK TO FINALLY REBOUND INTO THE
LOWER 60S.
DISTURBANCES IN THE NW FLOW ALOFT ON THE BACK-SIDE OF THE UPPER
TROUGH OVER THE WESTERN ATLANTIC COULD BRING EPISODIC CLOUDINESS
BUT IT SHOULD REMAIN DRY THROUGH THE PERIOD.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 222 PM SUNDAY...
24 HOUR TAF PERIOD:
HIGH CONFIDENCE THAT LOW END MVFR TO IFR CIGS AND VISBYS WILL
CONTINUE INTO THE OVERNIGHT HOURS AS RAIN CONTINUES TO FALL. SHOULD
SEE A BREAK IN THE RAINFALL FROM SW TO NW LATE THIS AFTERNOON...
HOWEVER THERE WILL BE LITTLE...IF ANY...IMPROVEMENT IN AVIATION
CONDITIONS DURING THIS TIME. ANOTHER ROUND OF RAINFALL...THIS TIME
MORE SHOWERY IN NATURE...WILL MOVE THROUGH FROM WEST TO EAST AHEAD
OF A COLD FRONT OVERNIGHT. AS THE FRONT MOVES THROUGH IT WILL SCOUR
OUT THE LOW CLOUDS AND CEILINGS YIELDING IMPROVING AVIATION
CONDITIONS AFTER DAYBREAK. WILL SEE A DECREASE IN WINDS OVERNIGHT AS
THE THEY BACK FROM NE TO NW. THEREAFTER...LOW END VFR CONDITIONS
SHOULD PREVAIL THROUGH THE END OF THE TAF PERIOD...WITH THE MAIN
CONCERN LATE MONDAY MORNING TO EARLY MONDAY AFTERNOON BEING STRONG
GUSTY WINDS...MAINLY OUT OF THE WEST/NORTHWEST.
LOOKING AHEAD:
CONDITIONS THROUGH TUESDAY WEDNESDAY WILL BE SOMEWHAT UNSETTLED AND
THE CHANCE FOR A RAIN OR SNOW SHOWER ACROSS THE NORTH ON MONDAY AND
TUESDAY WITH A DECREASE IN CIGS CANNOT BE COMPLETELY RULED OUT.
OTHERWISE...EXPECT MAINLY BROKEN TO OVERCAST VFR CONDITIONS THROUGH
WEDNESDAY...WITH DECREASING CLOUDS THEREAFTER.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...KC/BLAES
SHORT TERM...CBL
LONG TERM...CBL
AVIATION...KC
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
640 PM EDT SUN MAR 24 2013
.SYNOPSIS...
LOW PRESSURE OVER KENTUCKY WILL MOVE ACROSS SOUTHERN OHIO
OVERNIGHT. THE LOW WILL WEAKEN ON MONDAY AS A NEW LOW DEEPENS
RAPIDLY OFF THE MID ATLANTIC COAST. THIS DEEP LOW WILL EXTEND A
TROUGH WEST ACROSS THE GREAT LAKES REGION INTO WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
UPDATE ALREADY OUT. GIVEN DRY NE FLOW...CURRENT OBS AND LATEST
RADAR HAVE SLOWED DOWN THE ONSET OF THE SNOW A COUPLE OF HOURS
MOST AREAS. CURRENT RADAR RETURNS OVER THE LOCAL AREA ARE JUST
CLOUDS AND VIRGA. THE SNOW SHOULD REACH THE SOUTHERN END OF THE
AREA AFTER 00Z AND KMFD AROUND 03Z. IT WILL BE AFTER MIDNIGHT
BEFORE ANYTHING MORE THAN FLURRIES FALLS IN THE CLEVELAND AREA.
ORIGINAL...GUIDANCE CONVERGING ON A SOLUTION BRINGING THE SURFACE LOW FROM
WESTERN KENTUCKY INTO SOUTHERN OHIO OVERNIGHT. WEAK WAVE
INCREASING RETURN ON THE RADAR ACROSS CENTRAL AND SOUTHERN OHIO
THROUGH THE AFTERNOON. MUCH OF THIS ACROSS THE NORTHWEST AND NORTH
CENTRAL COUNTIES HAS BEEN VIRGA ALTHOUGH THERE ARE POCKETS OF
LIGHT SNOW AS WELL. FOLLOWING THE HRRR THIS PRECIP WILL CONTINUE
TO SPREAD INTO THE AREA BUT THEN WEAKEN AND DISSIPATE EARLY
EVENING. WILL HAVE CHANCE POPS IN PLACE TO COVER THE SNOW WITH
THIS ADVANCE WAVE. OTHERWISE MAIN PRECIP ASSOCIATED WITH THE STORM
SYSTEM NOW MOVING INTO/THRU SRN INDIANA AND ILLINOIS.
AGAIN...FOLLOWING HRRR EXPECT THIS TO MOVE INTO OUR AREA FROM THE
SSW BETWEEN 00-03Z. SNOW WILL CONTINUE TO MOVE INTO THE AREA FROM
THE SOUTH WITH MODERATE SNOW LIKELY COVERING THE SOUTHERN TIER OF
COUNTIES FROM 05Z-10Z. EXPECTING 4-6 INCHES ACROSS THE SOUTHERN
TIER WITH 3-5 FURTHER NORTH IN THE ADVISORY.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/...
ADVISORY/WARNING WILL BE ON GOING AT 12Z WITH SNOW LIKELY OCCURRING
ACROSS MUCH OF THE AREA. EXPECTING ANOTHER COUPLE INCHES ACROSS
THE SOUTH/SOUTHEAST COUNTIES THAT WILL BRING STORM TOTALS IN THE
WARNING AREA TO 5 TO 7...POSSIBLY A FEW 8`S WITH 3 TO 5...POSSIBLY
6 IN THE ADVISORY AREA BY NOON. THROUGH THE AFTERNOON MOISTURE AND
LIFT WILL BE WEAKENING AS THE ENERGY OF THE SYSTEM TRANSLATES TO
THE EAST COAST AND THE OHIO SURFACE LOW FILLS. MONDAY NIGHT
THROUGH TUESDAY NIGHT WILL CONTINUE WITH LOW CHANCE POPS IN A
GENERALLY MOIST NORTHERLY CYCLONIC FLOW...STILL INFLUENCED BY THE
EXITING SURFACE LOW WELL OFF THE EAST COAST. MID WEEK HIGH
PRESSURE WILL TRY TO BUILD IN AS THE LOW GETS HALF WAY TO EUROPE.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A FEW LINGERING SNOW SHOWERS IN THE SNOWBELT ON THURSDAY WITH 850 MB
TEMPS ONLY MINUS 8C. MODELS IN REASONABLE AGREEMENT MOVING HIGH
PRESSURE OVER THE AREA DURING THE DAY ON FRIDAY. HIGH PRESSURE WILL
REMAIN OVER THE AREA WELL INTO THE WEEKEND. MODELS MOVE NEXT
SYSTEM THROUGH ON SUNDAY...LEANED TOWARD THE SLOWER GFS SLOWER.
SHOULD WARM INTO THE 40S ALLOWING FOR RAIN.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
LOW PRESSURE SOUTHEAST OF ST LOUIS WILL TRACK ACROSS SOUTHERN OHIO
OVERNIGHT. THIS WILL BE A SYNOPTIC SITUATION WHERE THE FURTHER
SOUTH...CLOSER TO THE LOW...THE MORE SNOW. OVERNIGHT EXPECT AROUND
2-4 INCHES CLOSE TO THE LAKESHORE WHILE 6+ INCHES ACROSS CENTRAL
OHIO. WIDESPREAD IFR/LIFR IN THE HEAVIER SNOW.
CONDITIONS WILL GRADUALLY IMPROVE FROM THE WEST MONDAY MORNING AS
LOW SHIFTS EAST OF THE AREA.
NORTHEAST WINDS GUSTING INTO THE MID 20S WILL CONTINUE INTO MONDAY.
.OUTLOOK...NON VFR IN SHSN CONTINUING INTO WEDNESDAY.
&&
.MARINE...
LOW PRESSURE OVER KENTUCKY WILL MOVE ACROSS SOUTHERN OHIO TONIGHT.
AS IT DOES WINDS WIND INCREASE TO 20 TO 25 KNOTS ACROSS ENTIRE LAKE.
WINDS TURN TO THE NORTHWEST AS THE LOW MOVES OFF THE MID ATLANTIC
COAST MONDAY AFTERNOON. CONDITIONS DROP BELOW SMALL CRAFT ADVISORY
CRITERIA TUESDAY AS GRADIENT WEAKENS. HIGH PRESSURE FINALLY BUILDS
OVER THE LAKE ON FRIDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...WINTER STORM WARNING UNTIL NOON EDT MONDAY FOR OHZ036>038-047.
WINTER WEATHER ADVISORY UNTIL NOON EDT MONDAY FOR OHZ017>022-
027>033.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT TUESDAY FOR LEZ142>149.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK/KUBINA
SHORT TERM...TK
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
336 PM EDT SUN MAR 24 2013
.SYNOPSIS...
LOW PRESSURE OVER KENTUCKY WILL MOVE ACROSS SOUTHERN OHIO
OVERNIGHT. THE LOW WILL WEAKEN ON MONDAY AS A NEW LOW DEEPENS
RAPIDLY OFF THE MID ATLANTIC COAST. THIS DEEP LOW WILL EXTEND A
TROUGH WEST ACROSS THE GREAT LAKES REGION INTO WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
GUIDANCE CONVERGING ON A SOLUTION BRINGING THE SURFACE LOW FROM
WESTERN KENTUCKY INTO SOUTHERN OHIO OVERNIGHT. WEAK WAVE
INCREASING RETURN ON THE RADAR ACROSS CENTRAL AND SOUTHERN OHIO
THROUGH THE AFTERNOON. MUCH OF THIS ACROSS THE NORTHWEST AND NORTH
CENTRAL COUNTIES HAS BEEN VIRGA ALTHOUGH THERE ARE POCKETS OF LIGHT
SNOW AS WELL. FOLLOWING THE HRRR THIS PRECIP WILL CONTINUE TO
SPREAD INTO THE AREA BUT THEN WEAKEN AND DISSIPATE EARLY EVENING.
WILL HAVE CHANCE POPS IN PLACE TO COVER THE SNOW WITH THIS ADVANCE
WAVE. OTHERWISE MAIN PRECIP ASSOCIATED WITH THE STORM SYSTEM NOW
MOVING INTO/THRU SRN INDIANA AND ILLINOIS. AGAIN...FOLLOWING HRRR
EXPECT THIS TO MOVE INTO OUR AREA FROM THE SSW BETWEEN 00-03Z. SNOW
WILL CONTINUE TO MOVE INTO THE AREA FROM THE SOUTH WITH MODERATE
SNOW LIKELY COVERING THE SOUTHERN TIER OF COUNTIES FROM 05Z-10Z.
EXPECTING 4-6 INCHES ACROSS THE SOUTHERN TIER WITH 3-5 FURTHER
NORTH IN THE ADVISORY.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/...
ADVISORY/WARNING WILL BE ON GOING AT 12Z WITH SNOW LIKELY OCCURRING
ACROSS MUCH OF THE AREA. EXPECTING ANOTHER COUPLE INCHES ACROSS
THE SOUTH/SOUTHEAST COUNTIES THAT WILL BRING STORM TOTALS IN THE
WARNING AREA TO 5 TO 7...POSSIBLY A FEW 8`S WITH 3 TO 5...POSSIBLY
6 IN THE ADVISORY AREA BY NOON. THROUGH THE AFTERNOON MOISTURE AND
LIFT WILL BE WEAKENING AS THE ENERGY OF THE SYSTEM TRANSLATES TO
THE EAST COAST AND THE OHIO SURFACE LOW FILLS. MONDAY NIGHT
THROUGH TUESDAY NIGHT WILL CONTINUE WITH LOW CHANCE POPS IN A
GENERALLY MOIST NORTHERLY CYCLONIC FLOW...STILL INFLUENCED BY THE
EXITING SURFACE LOW WELL OFF THE EAST COAST. MID WEEK HIGH
PRESSURE WILL TRY TO BUILD IN AS THE LOW GETS HALF WAY TO EUROPE.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A FEW LINGERING SNOW SHOWERS IN THE SNOWBELT ON THURSDAY WITH 850 MB
TEMPS ONLY MINUS 8C. MODELS IN REASONABLE AGREEMENT MOVING HIGH
PRESSURE OVER THE AREA DURING THE DAY ON FRIDAY. HIGH PRESSURE WILL
REMAIN OVER THE AREA WELL INTO THE WEEKEND. MODELS MOVE NEXT
SYSTEM THROUGH ON SUNDAY...LEANED TOWARD THE SLOWER GFS SLOWER.
SHOULD WARM INTO THE 40S ALLOWING FOR RAIN.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
LOW PRESSURE SOUTHEAST OF ST LOUIS WILL TRACK ACROSS SOUTHERN OHIO
OVERNIGHT. THIS WILL BE A SYNOPTIC SITUATION WHERE THE FURTHER
SOUTH...CLOSER TO THE LOW...THE MORE SNOW. OVERNIGHT EXPECT AROUND
2-4 INCHES CLOSE TO THE LAKESHORE WHILE 6+ INCHES ACROSS CENTRAL
OHIO. WIDESPREAD IFR/LIFR IN THE HEAVIER SNOW.
CONDITIONS WILL GRADUALLY IMPROVE FROM THE WEST MONDAY MORNING AS
LOW SHIFTS EAST OF THE AREA.
NORTHEAST WINDS GUSTING INTO THE MID 20S WILL CONTINUE INTO MONDAY.
.OUTLOOK...NON VFR IN SHSN CONTINUING INTO WEDNESDAY.
&&
.MARINE...
LOW PRESSURE OVER KENTUCKY WILL MOVE ACROSS SOUTHERN OHIO TONIGHT.
AS IT DOES WINDS WIND INCREASE TO 20 TO 25 KNOTS ACROSS ENTIRE LAKE.
WINDS TURN TO THE NORTHWEST AS THE LOW MOVES OFF THE MID ATLANTIC
COAST MONDAY AFTERNOON. CONDITIONS DROP BELOW SMALL CRAFT ADVISORY
CRITERIA TUESDAY AS GRADIENT WEAKENS. HIGH PRESSURE FINALLY BUILDS
OVER THE LAKE ON FRIDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...WINTER STORM WARNING UNTIL NOON EDT MONDAY FOR OHZ036>038-047.
WINTER WEATHER ADVISORY UNTIL NOON EDT MONDAY FOR OHZ017>022-
027>033.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT TUESDAY FOR LEZ142>149.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
144 PM EDT SUN MAR 24 2013
.SYNOPSIS...
BELOW NORMAL TEMPERATURES THROUGH NEXT WEEK. WINTER STORM AFFECTS
THE AREA TODAY THROUGH LATE MONDAY...BRINGING MAINLY RAIN SUNDAY...
CHANGING TO ALL SNOW MONDAY NIGHT. UPSLOPE SNOW EVENT FOLLOWS.
&&
.NEAR TERM /THROUGH TONIGHT/...
630 AM UPDATE...FRESHENED UP GRIDS A BIT...BUT NO SIGNIFICANT
CHANGES.
PREVIOUS DISCUSSION...
WHAT A COMPLEX SYSTEM. ON THE POSITIVE SIDE...MODELS AGREE VERY WELL
ON THE MASS AND QPF FIELDS OF THE SYSTEM AFFECTING US THIS PERIOD.
PARENT SURFACE LOW LIFTS NORTHEAST INTO SOUTHERN OHIO AHEAD OF A
DEVELOPING STRONG UPPER LOW OVER THE MID MISSISSIPPI VALLEY...THEN
REDEVELOPS LATER TONIGHT JUST OFF THE MID ATLANTIC COAST AS THE
APPROACHING UPPER SYSTEM TAPS INTO THE GULF STREAM WATERS. LOOKS LIKE
ONE SLUG OF QPF THIS AFTERNOON WITH A LEAD SHORT WAVE AND ANOTHER
TONIGHT WITH THE UPPER LOW ITSELF. HOWEVER...THE THERMAL FIELDS WITH
THE SYSTEM DO NOT AGREE WELL...AND THIS IS CRITICAL TO THE TYPE OF
PRECIP IN A QPF REGIME OF BETWEEN HALF AN INCH AND AN INCH.
NORMALLY...I REPEAT NORMALLY...WITH THE TRACK OF THE PARENT SURFACE
LOW WE WOULD EXPECT A BRIEF PERIOD OF WINTRY MIX TO RAIN IN THE
LOWLANDS AS THE TYPICAL WARM WEDGE IN LOW LEVEL SOUTHEASTERLY FLOW
SURGES AHEAD OF THE LOW. WE WOULD KEEP A WINTRY TYPE PRECIP REGIME
IN THE NORTHERN MOUNTAINS WITH THE TYPICAL UPSLOPE AND COLD AIR
DAMMING. WE WOULD THEN SEE A TRANSITION BACK TO SNOW LATER TONIGHT
AS COLDER AIR WORKS IN ALOFT.
HOWEVER...THE TRACK OF THE UPPER SYSTEM IS EAST RIGHT ACROSS OUR
AREA. THIS PREVENTS THE WARM WEDGE FROM GETTING TOO FAR NORTH THIS
AFTERNOON AS THE HEAVIER PRECIP ARRIVES. THE NAM AND RUC ARE THE
WARM OUTLIER FOR THE WARM WEDGE...WHILE THE GFS AND EURO ARE COLDER.
THIS COLDER SCENARIO APPEARS TO BE DUE TO STRONG UPPER DYNAMICS AND
WET BULBING WHIT THE PRECIP. EVEN THE SREF SHOWS THIS.
AM GOING WITH THE COOLER SCENARIO. YES...THE MAV/LAMP TEMP GUIDANCE
CURIOUSLY SHOW HIGHS IN THE 40S FOR MUCH OF THE LOWLANDS TODAY...BUT
THIS IS DISCOUNTED BY THE GUIDANCE NOT SEEMING TO ACCOUNT FOR WET
BULB COOLING. SO WILL ACTUALLY USE THE COOLER NAM SURFACE TEMPS BUT
THE GFS/EURO AND SREF COOLER TEMPS ALOFT.
ALL THIS PANS OUT TO TEMPS TODAY REMAINING IN THE 30S ACROSS THE
MOST OF THE LOWLANDS...WHILE BELOW FREEZING TEMPS OCCUR IN THE
NORTHERN MOUNTAINS. THIS WILL BE COLD ENOUGH FOR ALL SNOW NORTHERN
MOUNTAINS...SNOW WITH MIXED RAIN AND SLEET ACROSS THE FAR
NORTH...AND BRIEF WINTRY MIX TO RAIN ELSEWHERE. WITH THE AMOUNT OF
QPF...COULD BE HEAVY WET SNOW ACROSS THE FAR NORTH. THUS...ISSUED A
WINTER WEATHER ADVISORY FOR THE AREA LATER THIS AFTERNOON AND
ESPECIALLY TONIGHT WITH THE SECOND QPF SLUG. WINTER STORM WARNING
REMAINS IN EFFECT FOR THE NORTHERN MOUNTAINS.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
LOW PRESSURE SYSTEM EXITS TO THE EAST...ONLY TO HAVE CYCLONIC FLOW
REINFORCED BY A SECONDARY TROUGH SWINGING THROUGH THE TENNESSEE
VALLEY INTO THE MID ATLANTIC. IN THE LOWER LEVELS...FLOW WILL TURN
AROUND TO THE NORTHWEST THAT WILL EVENTUALLY TAP INTO SOME GREAT
LAKES MOISTURE. COLD POOL ALOFT WILL SETTLE INTO THE AREA...AND WILL
NOT RELINQUISH ITS GRIP ALL THE WAY INTO MID WEEK...WITH 850MB
TEMPERATURES VARYING FROM -7C TO -10C. IN THE END...THIS RESULTS IN
POPS FOR THE BULK OF THE SHORT TERM FORECAST ENHANCED BY THE
AFOREMENTIONED SECONDARY TROUGH AXIS MONDAY EVENING INTO
TUESDAY...AND THEN THE CONVECTIVE NATURE OF THE NORTHWEST FLOW INTO
WEDNESDAY.
UNDERCUT THE GUIDANCE FOR THE DAYTIME MAXIMUM TEMPERATURES GIVEN THE
CLOUD COVER...PRECIPITATION...NORTHWESTERLY FLOW...AND COLD POOL
ALOFT. WITH THAT BEING SAID...GIVEN THE TIME OF YEAR...BEST CHANCE
FOR SNOW ACCUMULATIONS WILL BE DURING THE OVERNIGHT HOURS. HAVE
DAYTIME TEMPERATURES CLIMBING ABOVE FREEZING IN MOST
CASES...ALTHOUGH THE MOUNTAINS WILL HOVER AROUND FREEZING OR STAY
BELOW IN THE CASE OF THE HIGHER ELEVATIONS OF THE NORTHEAST
MOUNTAINS. SO...EXPECT SOME MELTING DURING THE DAY...WITH SUN ANGLE
AND LONGER DAYS THAN NIGHTS ALSO CONTRIBUTING TO THIS EQUATION.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
USED THE ECMWF ENSEMBLE MEAN THROUGH THE PERIOD. SOME UPSLOPE SNOW
SHOWERS REMAIN A POSSIBILITY TUESDAY NIGHT INTO EARLY THURSDAY. HIGH
PRESSURE THEN BUILDS IN FOR THURSDAY NIGHT AND FRIDAY. A LOW
CONFIDENCE SYSTEM THEN SLIDES SOUTH OF THE AREA FRIDAY NIGHT AND
SATURDAY...CAUSING SOME SMALL POPS OVER OUR FORECAST AREA.
&&
.AVIATION /17Z SUNDAY THROUGH THURSDAY/...
AN APPROACHING LOW PRESSURE SYSTEM IS PUSHING MOISTURE ACROSS THE
REGION. WARM AIR HAS SURGED UP THE WESTERN SLOPES OF THE MOUNTAINS.
THIS WILL CAUSE RAIN WEST OF THE SPINE...AND SNOW TO THE EAST.
CEILINGS WILL GRADUALLY COLLAPSE AS THE RAIN MOVES IN...ALTHOUGH A
SOUTHEAST DOWNSLOPE WIND ALONG THE WESTERN SLOPES WILL PROVIDE A
SMALL AREA OF HIGHER CEILINGS. COLDER AIR WILL WRAP AROUND THE LOW
AND MOVE IN TONIGHT...CHANGING THE RAIN TO SNOW AND CREATING A LOW
STRATUS DECK. SNOW SHOWERS CAN BE EXPECTED ON MONDAY WITH THE
STRATUS DECK CONTINUING.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY...
FORECAST CONFIDENCE...MEDIUM.
ALTERNATE SCENARIOS: CEILINGS WITH THIS SYSTEM COULD VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY L L L L L L L L L M M M
HTS CONSISTENCY M H H H H H H H H M H H
BKW CONSISTENCY M M M M M M M M M M M M
EKN CONSISTENCY L L M M M M M M L L M M
PKB CONSISTENCY H H M M M L M M M M M M
CKB CONSISTENCY H H M M M M M M M M M M
AFTER 18Z MONDAY...
IFR CONDITIONS POSSIBLE IN SNOW SHOWERS MONDAY AFTERNOON AND TUESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER WEATHER ADVISORY UNTIL 11 AM EDT MONDAY FOR WVZ010-011-
020-031-032-039-040.
WINTER STORM WARNING UNTIL 2 PM EDT TUESDAY FOR WVZ038-046-047.
OH...WINTER WEATHER ADVISORY UNTIL 11 AM EDT MONDAY FOR OHZ066-067-
075-076-084.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JMV/26
NEAR TERM...JMV
SHORT TERM...26
LONG TERM...RPY
AVIATION...RPY
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
221 PM CDT SUN MAR 24 2013
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
221 PM CDT SUN MAR 24 2013
SNOW COMES TO AN END THIS EVENING WITH DRY AND BELOW NORMAL
TEMPERATURES EXPECTED FOR THE EARLY HALF OF THE WEEK.
CURRENTLY...LIGHT SNOW IS FALLING ACROSS PORTIONS OF THE REGION AS
A PAIR OF CLOSED MID LEVEL LOWS TRACK NEAR THE REGION. THE MORE
POTENT OF THESE LOWS IS MOVING INTO SOUTHERN ILLINOIS WHILE THE
OTHER LOW HAS STALLED OUT ACROSS THE DAKOTAS. A COUPLE BANDS OF
SNOW DEVELOPED ACROSS THE REGION THIS AFTERNOON WHERE THE LIFT
FROM THE TROUGH WAS STRONG ENOUGH TO SATURATE THROUGH THE COLUMN.
AS THE LIFT WEAKENS TONIGHT AND DRY MID LEVEL AIR ADVECTS IN FROM
THE NORTH...EXPECT THAT THE SNOW WILL QUICKLY COME TO AN END FROM
NORTH TO SOUTH. THE 24.16Z HRRR KEEPS THIS SNOW ACROSS PORTIONS OF
NORTHEAST IOWA AND SOUTHEAST MINNESOTA THROUGH 5Z...WHICH APPEARS
TO BE REASONABLE GIVEN RECENT TRENDS. OVERALL IMPACT OF THIS SNOW
HAS BEEN ON THE LOW SIDE WITH ROAD TEMPERATURES IN THE 40 TO 50F
RANGE THIS AFTERNOON WITH MUCH OF THE SNOW MELTING ON CONTACT
WITH THE ROADS. HOWEVER...AS THE SUN AND TEMPERATURES DROP
TONIGHT...SOME OF THE WET ROADS COULD HAVE SOME ICY PATCHES FORM
IF THEY DO NOT DRY OFF FIRST. CLOUD COVER WILL REMAIN OVERCAST
THROUGH THE NIGHT AS LOW AND HIGH LEVEL MOISTURE CONTENT REMAINS
FAIRLY HIGH.
WITH THE DRY NORTHWEST FLOW IN PLACE THROUGH MID WEEK FROM THE
SURFACE THROUGH THE UPPER PORTIONS OF THE ATMOSPHERE...THE MAIN
FORECAST CHALLENGES WILL BE WITH CLOUD COVER AND TEMPERATURES. HOW
THE TEMPERATURES PAN OUT WILL DIRECTLY TIE INTO HOW MUCH CLOUD
COVER THERE IS. BASED ON 24.12Z NAM/GFS RH FIELDS AND
SOUNDINGS...IT APPEARS THAT THE CLOUDS SHOULD LINGER THROUGH
TUESDAY BEFORE A RIDGE OF HIGH PRESSURE MOVES IN FROM THE WEST
TUESDAY NIGHT. THERE COULD BE A FEW BREAKS IN THE CLOUDS ON
TUESDAY...BUT OVERALL BELIEVE THAT THE SKIES WILL MAINLY BE CLOUDY
UNTIL THE RIDGE GETS IN. 850MB TEMPERATURES DO DROP SLIGHTLY OVER
THE NEXT COUPLE DAYS...FROM -10C TO -12C...BUT THEN START TO
REBOUND GOING INTO WEDNESDAY AS THE RIDGE AXIS APPROACHES FROM THE
WEST. BASED ON THE GRADUALLY THINNING CLOUD COVER...HAVE GONE
WITH A SIMILAR GRADUAL INCREASE IN TEMPERATURES.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
221 PM CDT SUN MAR 24 2013
THIS WARMING TREND WILL CONTINUE THROUGH THE REST OF THE WEEK AS
THE LONG WAVE UPPER LEVEL TROUGH OVER THE EASTERN HALF OF THE US
PROGRESSES EASTWARD AND UPPER LEVEL RIDGING TRIES TO DEVELOP
ACROSS THE CENTRAL US. WARMER LOW LEVEL AIR WILL ADVECT INTO THE
REGION FROM THE SOUTHWEST WITH 850MB TEMPERATURES REACHING +2C BY
SATURDAY AHEAD OF THE NEXT SYSTEM TO IMPACT THE REGION. THIS NEXT
SYSTEM THAT THE 24.12Z GFS/ECMWF BRING INTO THE REGION ON
SATURDAY/SATURDAY NIGHT IS CURRENTLY OFF THE WEST COAST OF ALASKA
AND APPEARS TO STALL OUT OVER THE PACIFIC NW AROUND MID WEEK.
THERMAL PROFILES FROM BOTH THE 24.12Z GFS/ECMWF SUGGEST THAT THE
PRECIPITATION WILL REACH THE GROUND AS RAIN DUE TO A DEEP WARM
LAYER FROM THE SURFACE UP TO 800MB. WITH FORECAST HIGH
TEMPERATURES OF AROUND 50F FRIDAY INTO SUNDAY AND A PERIOD OF RAIN
COMING THROUGH...WILL HAVE TO WATCH FOR SOME POTENTIAL FLOODING ON
AREA RIVERS SHOULD THIS FORECAST CONTINUE TO TREND THIS WAY.
&&
.AVIATION...THROUGH 18Z MONDAY
1247 PM CDT SUN MAR 24 2013
BANDS OF LIGHT SNOW ARE CURRENTLY ROTATING THROUGH THE REGION AND
WILL PRODUCE MVFR TO IFR CONDITIONS AT KRST/KLSE INTO THE
AFTERNOON. VISIBILITIES HAVE BOUNCED AROUND BETWEEN 5 AND
2SM...AND AS SATURATION WINS OUT AGAINST THE DRIER AIR IN THE LOW
LEVELS...WILL GO AHEAD AND FAVOR THE LOWER END OF PROBABILITIES
THIS AFTERNOON. THE LOWER CEILINGS ARE LAGGING SLIGHTLY...BUT IFR
CEILINGS SHOULD REACH KRST IN A FEW HOURS. CURRENT THINKING IS
THAT KLSE SHOULD REMAIN WITH LOW-END MVFR CEILINGS. LATEST MESO
MODELS SHOW THE BANDS OF LIGHT SNOW LASTING INTO THE EARLY EVENING
HOURS...BEFORE PRECIPITATION WANES AND MOVES SOUTH/EAST. CLOUDS
WILL PERSIST THROUGH THE REMAINDER OF THE PERIOD...AND SHOULD
GENERALLY BE IN THE 1500 TO 2500 FT RANGE ONCE THE SNOW ENDS. THERE
COULD BE SOME LIFTING/IMPROVEMENT IN THE MORNING HOURS
MONDAY...BUT CONFIDENCE IN THIS MESSY CYCLONIC FLOW IS LOW...SO
HAVE REMAINED ON THE PESSIMISTIC SIDE OF MODEL GUIDANCE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
221 PM CDT SUN MAR 24 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION.....ZT
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1146 AM CDT SUN MAR 24 2013
.UPDATE...
WATER VAPOR IMAGERY AND 500MB RUC ANALYSIS ARE SHOWING A SHORTWAVE
MOVING NORTHEAST ACROSS WISCONSIN THIS MORNING. THIS AREA IS ALSO
BENEATH UPPER LEVEL DIVERGENCE DUE TO THE LOCATION OF THE UPPER JET.
PERIODS OF LIGHT SNOW DEVELOPED ACROSS MUCH OF SOUTHERN WI DURING
THE MORNING.
A BAND OF HIGHER REFLECTIVITY SET UP OVER THE CENTRAL PART OF THE
FORECAST AREA FROM MADISON THROUGH WATERTOWN AND NOW JUNEAU INTO
OZAUKEE COUNTY. THIS AREA SEEMS TO BE COINCIDENT WITH WEAK 700-600MB
WARM AIR ADVECTION AND FRONTOGENESIS. OTHER OBSERVATION SITES AND
RADAR SHOW LIGHT SNOW ACROSS OTHER PARTS OF THE FORECAST AREA LATE
THIS MORNING. VISIBILITIES WITHIN THE AREAS OF HIGHER REFLECTIVITY
ARE DOWN TO A HALF MILE. THE BANDS ARE MOVING SLOWLY...SO LOCATIONS
UNDER A BAND COULD SEE AN INCH ACCUMULATION WITHIN AN HOUR. THERE IS
NO SNOW FALLING IN SOUTHERN MILWAUKEE COUNTY AND RACINE AND KENOSHA
COUNTIES AT THIS TIME...AND NOT SURE IF/WHEN IT WILL FILL IN.
THE SHORTWAVE WILL CONTINUE OFF TO THE NORTHEAST AND THE MAIN UPPER
LOW OVER MISSOURI WILL MOVE EAST TODAY. THE PRECIPITATION ON THE
NORTH SIDE OF THAT UPPER LOW AND WITHIN THE INVERTED SURFACE TROUGH
SHOULD CLIP SOUTHWEST AND SOUTH CENTRAL WI DURING THE AFTERNOON.
MUCH LESS CONFIDENCE ON THE PRECIP MAKING IT INTO SOUTHEAST WI.
OVERALL...EXPECTING THE SNOW TO GRADUALLY DIMINISH OVER THE FORECAST
AREA THIS AFTERNOON GIVEN THE LOSS OF THE BETTER UPPER DYNAMICS.
FORECAST MODELS SUGGEST AN AREA OF 700-600MB WARM AIR ADVECTION AND
FRONTOGENESIS SITTING OVER THE CENTRAL FORECAST AREA THROUGH THE
AFTERNOON SO THERE MAY BE A BAND OF HEAVIER SNOW THAT PERSISTS.
THEN THERE IS THE LAKE EFFECT COMPONENT OF THE SNOW. RECENT AMDAR
AIRCRAFT SOUNDINGS FROM MITCHELL MILWAUKEE AIRPORT SHOW 850MB TEMP
OF -7 TO -8C WHICH WOULD GIVE A LAKE-850MB TEMP DIFFERENCE OF 9 TO
10C...WHICH IS MARGINAL FOR LAKE EFFECT SNOW PRODUCTION. EXPECT THE
LAKE TO CONTRIBUTE VERY LIGHT SNOW TO EASTERN PORTIONS OF THE
FORECAST AREA. SOUTHEAST WI WILL HAVE A BETTER CHANCE OF SEEING THIS
SNOW LATER THIS EVENING AS THE WINDS SHIFT TO THE NORTH.
&&
.AVIATION/18Z TAFS/...
SLOW-MOVING AREAS OF HEAVIER SNOW APPARENT ON RADAR IMAGERY COULD
PRODUCE A QUICK INCH OF SNOW IN AN HOUR. VISIBILITIES DOWN TO A HALF
MILE HAVE BEEN REPORTED WITHIN THESE BANDS. PERIODS OF LIGHT SNOW IS
EXPECTED TO PERSIST ACROSS ALL OF SOUTHERN WI THROUGH THE AFTERNOON
AND DIMINISH BY EARLY EVENING. MVFR CEILINGS WILL PREVAIL...ALTHOUGH
CIGS COULD DIP TO IFR IN THE HEAVIER SNOW BANDS.
THE SURFACE TO 5000 FT FLOW INCREASES TONIGHT AND SWITCHES FROM EAST
TO NORTHEAST. INSTABILITY OVER THE LAKE WILL HELP PRODUCE LAKE
EFFECT SNOW SHOWERS NEAR LAKE MICHIGAN AS THE SYSTEM SNOW SLOWLY
DIMINISHES. ACCUMULATIONS TONIGHT SHOULD BE SPOTTY AND LESS THAN 1
INCH.
&&
.MARINE...
SHORT TERM MODELS ARE SHOWING HIGHER WINDS DEVELOPING OVER SOUTHERN
LAKE MICHIGAN LATE THIS AFTERNOON THROUGH MUCH OF TONIGHT. UPGRADED
TO A GALE WARNING FOR THE SOUTHERN MARINE ZONE FROM WIND POINT TO
WINTHROP HARBOR FROM 22Z THROUGH 09Z TONIGHT. WILL NEED TO RAMP DOWN
TO A SMALL CRAFT ADVISORY AGAIN AFTER THAT EXPIRES.
A SMALL CRAFT ADVISORY IS IN EFFECT ELSEWHERE THROUGH MONDAY NIGHT
DUE TO BRISK NORTHEAST WINDS AND HIGH WAVES. THE BRISK WINDS WILL BE
PRODUCED BY STRONG LOW PRESSURE SLOWLY MOVING ALONG THE OHIO RIVER
VALLEY.
&&
.PREV DISCUSSION... /ISSUED 331 AM CDT SUN MAR 24 2013/
SHORT TERM...
TODAY AND TONIGHT-FORECAST CONFIDENCE MEDIUM.
AN INITIAL 500MB SHORTWAVE WILL MOVE NORTHEAST THROUGH SOUTHERN
WISCONSIN TODAY. MODELS SHOW AN ASSOCIATED BULLS-EYE OF UPPER LEVEL
DIFLUENCE AT JET STREAM LEVEL. SATELLITE PICTURES REFLECT THESE
FEATURES WITH COOLER AND HIGHER CLOUD TOPS. WEAK ISENTROPIC LIFT IS
ALSO FORECAST WITH THIS SHORT WAVE IN THE 10 TO 20 THSD FT LAYER
WHERE IT SATURATES IN THE -12 TO -18C RANGE. CORRESPONDINGLY...RADAR
SHOWS LIGHT SNOW TRYING TO INCH IT/S WAY NORTHEAST INTO SOUTHERN
WI...BUT NOT MUCH REACHING THE GROUND DUE TO DRY NORTHEAST LOW-LEVEL
FLOW. BLEND OF MODELS SUGGESTS SOUTHWEST HALF OF MY COUNTY WARNING
AREA HAS BEST CHANCES FOR SOME LIGHT SNOW TODAY...WITH ACCUMS LESS
THAN 1 INCH. NORTHEAST PART OF MY COUNTY WARNING AREA WILL BE LAST
TO SEE ANY SNOW. MAX TEMPS TODAY IN THE LOWER TO MID 30S...SO ACCUMS
ON ROAD SURFACES SHOULD BE MINIMAL.
FOR TONIGHT LOW-LEVEL FLOW SWITCHES FROM EAST TO NORTHEAST AS THE
UPPER LOW AND SURFACE LOW SWING EAST-NORTHEAST UP THE OHIO RIVER
VALLEY. NOT MUCH IN THE WAY OF SHORT-WAVE ENERGY FOR SOUTHERN
WISCONSIN TONIGHT. ALSO...MODELS CONTINUE TO SHOW MID-LEVEL DRYING
AND NO ISENTROPIC LIFT...SO CHANCES OF GENERAL LIGHT SNOW DROP OFF
TONIGHT. HOWEVER...MODELS DO SHOW A MORE FAVORABLE NORTHEAST FETCH
OVER LAKE MICHIGAN INTO SOUTHEASTERN WISCONSIN. DELTA-T VALUES ARE
ON ORDER OF 10 TO 12 SUGGESTING SOME LAKE-EFFECT SHOWERS WILL
DEVELOP. BUFKIT SOUNDINGS DO DEEPEN THE NEAR SATURATED LOW-LEVEL AIR
NEAR LAKE MICHIGAN TONIGHT...UP TO 6 TO 7 THSD FT AT MILWAUKEE BY
END OF NIGHT. WILL KEEP MENTION OF CHANCE OF SNOW SHOWERS NEAR LAKE
MICHIGAN TONIGHT.
MONDAY-FORECAST CONFIDENCE HIGH
LOW OVER OHIO FILLS RAPIDLY AS COASTAL SECONDARY CYCLOGENESIS
TAKES OVER IN THE MIDDLE ATLANTIC REGION. FLOW REGION THROUGH DEEP
LAYER TRANSITIONS FROM NORTHEAST TO NORTHERLY...AND 500 MB HEIGHTS
RISE ABOUT 50 METERS OVER SOUTHERN WISCONSIN. 850 MB TEMPS AROUND
-10C RESULT IN LAKE DELTA T OF ABOUT 13C. RAN THROUGH LAKE SNOW
CHECKLIST AND IT INDICATES A MINOR EVENT...PERHAPS AN INCH. HAVE
SCATTERED SNOW SHOWERS NEAR THE SHORE BUT THIS MAY NEED TO BE
BUMPED UP LATER.
TUESDAY-FORECAST CONFIDENCE HIGH
FLOW REGIME TURNS FROM NORTHERLY TO NORTHWEST...WITH LITTLE CHANGE
IN AIRMASS. STILL RUNNING ABOUT 10 DEGREES BELOW NORMAL FOR LATE
MARCH WITH CONSENSUS 925 MB TEMPS ONLY RISING ABOUT 1C FROM
MONDAY TO ABOUT -4 OR -5C. NOT IMPOSSIBLE FOR CONVECTIVE SNOW
SHOWERS BENEATH UPPER TROUGH BUT THE MODELS BATTING
AVERAGE...ESPECIALLY THE GFS...NOT TOO GOOD AND SEEMS TO OVERDO
THESE SITUATIONS.
LONG TERM...
WEDNESDAY AND THURSDAY-FORECAST CONFIDENCE MEDIUM
RATHER QUIET PATTER WITH NORTHWEST FLOW ALOFT AND POLAR HIGH
COVERING THE GREAT LAKES AREA. HEIGHTS GRADUALLY RISE ABOUT 30 OR
40 METERS EACH DAY AND GRADUAL MODERATION OF AIR MASS CONTINUES.
CONSENSUS 925 TEMPS RISE TO ABOUT -3C ON WEDNESDAY AND GET TO
ABOUT 0C ON THURSDAY. NOT QUITE READY TO DANCE IN THE STREETS BUT
UPPER 30S TO LOWER 40S SOUNDS PRETTY GOOD EVEN IF STILL 5 TO 10
DEGREES BELOW NORMAL.
FRIDAY AND SATURDAY-FORECAST CONFIDENCE MEDIUM
MODELS DO NOT PROVIDE MUCH CONFIDENCE IN TIMING OF ANY MINOR
EVENTS IN NORTHWEST FLOW. GEM HAS DECENT SHORTWAVE ON FRIDAY BUT
GFS AND ECMWF SHOW PERSISTENT SURFACE HIGH.
GFS AND ECMWF STARTING TO COME INTO BETTER AGREEMENT WITH SYSTEM
SATURDAY OVER MN/IA AREA AND MAY NEED TO ADD POPS SATURDAY NIGHT
IN LATER FORECASTS. FOR NOW LOOKS LIKE CONTINUED MODERATING TREND
WITH 925 MB TEMPS IN THE 0 TO +2C RANGE...WITH HIGHS RISING INTO
THE MIDDLE 40S. SO WE HAVE A SHOT AT NEAR NORMAL HIGHS BY THE END
OF MARCH.
OF NOTE IS THAT MADISON HAS JUST ONE DAY THIS MONTH WITH HIGH
TEMPERATURES REACHING NORMAL. IN JULY OF 2009 MADISON TIED THE
AVERAGE HIGH 3 TIMES BUT NEVER HAD AN ABOVE AVERAGE HIGH. IT IS
VERY UNUSUAL TO SEE A MONTH GO BY WHERE YOU DO NOT HAVE ABOVE
AVERAGE HIGH TEMPERATURES AT LEAST ONCE. IT WILL BE A CLOSE CALL
WITH UPPER 40S ON SUNDAY THE 31ST.
AVIATION/12Z TAFS/...
STRATUS DECK OFF OF LAKE MICHIGAN WILL KEEP CEILINGS IN THE MVFR
RANGE TODAY AND TONIGHT ACROSS SOUTHERN WISCONSIN. SYSTEM SNOW
SHOULD DROP VISIBILITIES TO 3 TO 5 MILES IN SPOTS. NOT EXPECTING IFR
CONDS DUE TO DRY LOW-LEVEL AIR 5 TO 10 THSD FEET AGL.
LIGHT WET SNOW IS EXPECTED TO SPREAD INTO SOUTHERN WISCONSIN SUNDAY
MORNING AND THEN TAPER OFF SUNDAY EVENING. THE BEST CHANCE FOR SNOW
WILL BE ALONG I-94 AND SOUTH SO THIS INCLUDES ALL THE TAF SITES.
HIGHEST ACCUMULATIONS OF 1 INCH OR LESS WILL LIKELY BE SOUTH AND
WEST OF THE TAF SITES...ESPECIALLY TOWARD THE WI/IA/IL BORDER.
THE SURFACE TO 5000 FT FLOW INCREASES TONIGHT AND SWITCHES FROM EAST
TO NORTHEAST. INSTABILITY OVER THE LAKE WILL HELP PRODUCE LAKE
EFFECT SNOW SHOWERS NEAR LAKE MICHIGAN AS THE SYSTEM SNOW SLOWLY
DIMINISHES. ACCUMULATIONS TONIGHT SHOULD BE SPOTTY AND LESS THAN 1
INCH.
MARINE...
A SMALL CRAFT ADVISORY IS IN EFFECT THIS MORNING THROUGH MONDAY
NIGHT DUE TO BRISK NORTHEAST WINDS AND HIGH WAVES. THE BRISK WINDS
WILL BE PRODUCED BY STRONG LOW PRESSURE SLOWLY MOVING ALONG THE
OHIO RIVER VALLEY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM CDT THIS AFTERNOON FOR LMZ646.
GALE WARNING FROM 5 PM THIS AFTERNOON TO 4 AM CDT MONDAY FOR
LMZ646.
SMALL CRAFT ADVISORY UNTIL 10 PM CDT MONDAY FOR LMZ643>645.
&&
$$
UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...KAPELA
MONDAY THROUGH SATURDAY...CRAVEN