Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/18/13
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
1005 PM EDT SUN MAR 17 2013
.UPDATE...
HAVE MADE SEVERAL MINOR TWEAKS TO GRIDS THIS EVENING. UPDATED TEMP
AND DEWPOINT TRENDS OF COURSE. MADE CHANGES TO SKY GRIDS AS WELL
TO INCREASE SKY COVER OVERNIGHT. REDUCED POPS UP NORTH AND
ADJUSTED POPS IN SOUTHERN ZONES TO MATCH MORE OF WHAT THE HRRR AND
OUR LOCAL WRF WERE REFLECTING FOR THE LIGHT RAIN MOVING TOWARD
SOUTH CAROLINA THIS EVENING. FOR TOMORROW...MADE SOME MINOR
ADJUSTMENTS TO HOURLY TEMPS AND DEWPOINTS TO REFLECT THE LOCATION
OF THE WEDGE FRONT IN NORTHEAST GEORGIA. KEPT THUNDER TRENDS
PRETTY MUCH THE SAME BUT DID INCREASE POPS EARLY IN THE DAY TO
ACCOUNT FOR HI-RES MODEL TRENDS...ALL WANTING TO BRING SHOWERS
INTO NORTHWEST GEORGIA AROUND 12Z. SPC SREF DOES BRING SBCAPE
250-500 J/KG BEFORE 18Z SO FEEL THAT KEEPING SLIGHT CHANCE THUNDER
IN THE MORNING IS THE PRUDENT COURSE OF ACTION.
TDP
&&
.PREV DISCUSSION... /ISSUED 758 PM EDT SUN MAR 17 2013/
PREV DISCUSSION... /ISSUED 333 PM EDT SUN MAR 17 2013/
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
CURRENT SATELLITE LOOP SHOWS INCREASED MID AND HIGH CLOUDS OVER THE
AREA WITH SHORTWAVE MOVING NE OUT OF THE GULF INTO SOUTH GA. THIS
WAVE MAY BRING SOME SHOWERS TO THE CSG AND MCN AREAS BUT THE
BIGGEST CONCERN IN THE SHORT TERM IS THE FRONTAL PASSAGE EXPECTED
MONDAY AFTERNOON INTO TUESDAY MORNING. THE CLOSED LOW PRESSURE
CENTER OVER MONTANA AND WYOMING WILL MOVE EAST AND DEEPEN OVER THE
NEXT 24-48 HOURS. THIS LOW CENTER BEGINS TO DEVELOP A FAIRLY
ORGANIZED COLD FRONT OVER NIGHT WITH THE TAIL END OF IT SWEEPING
THROUGH NORTH AND CENTRAL GA MONDAY NIGHT INTO TUESDAY MORNING.
EXPECT PRE-FRONTAL ACTIVITY MONDAY INTO MONDAY NIGHT...SO WILL
CONTINUE WITH CHANCE POPS ACROSS A LARGE PORTION OF THE AREA...AND
LIKELY POPS ACROSS NORTHWEST GEORGIA. THESE POPS WILL INCREASE
THROUGH THE DAY AS FRONT APPROACHES...AND CONTINUE TO INCREASE
THROUGH THE OVERNIGHT HOURS AS THE FRONT PUSHES THROUGH THE STATE.
SPC HAS MOST ALL OF NORTH GA AND A GOOD PORTION OF EASTERN GA
OUTLOOKED IN A SLIGHT RISK FOR MONDAY AND MONDAY NIGHT. MODELS
SUGGESTING SBCAPE...MUCAPE AND MLCAPE WILL BE NEAR IN THE 900-1100 J/KG
RANGE BY MONDAY AFTERNOON...AND GIVEN THE ENVIRONMENT...EXPECT
SURFACE BASED STORMS TO REALLY TAP INTO THE UNSTABLE ATMOSPHERE.
THE BEST LAPSE RATES ALSO PEAK AROUND 18Z MON TO 00Z TUE. STRONG
TO SEVERE STORMS CAN BE EXPECTED...AND PRIMARY CONCERN REMAINS TO
BE DAMAGING WINDS...THOUGH SOME ROTATION IS POSSIBLE WITHIN
STRONGER UPDRAFTS. MODELS SUGGESTING WEDGE IN PLACE ACROSS
NORTHEAST GEORGIA...WHICH WILL ACT TO STABILIZE THE WEDGED
AREA...BUT THE BOUNDARY ALONG THE PERIPHERY OF THE WEDGE WILL BE A
CATALYST FOR ENHANCED STORMS TO DEVELOP.
01
LONG TERM /TUESDAY THROUGH SUNDAY/...
COLD FRONT AND ASSOCIATED PRECIP WILL EXIT THE SW CWFA EARLY ON
TUESDAY. DRY AND COOLER THAN NORMAL TEMPS ARE EXPECTED TUESDAY
THROUGH WEDNESDAY NIGHT. A WARM FRONT OVER THE NORTHERN GULF OF
MEXICO WILL START MOVING NORTH TOWARDS THE COAST BY THE END OF THE
WEEK. CLOUDS AND PRECIP WILL INCREASE ACROSS THE REGION THURSDAY
INTO SATURDAY AS SEVERAL WAVES OF LOW PRESSURE MOVE EAST ALONG THE
BOUNDARY AS IT NEARS THE COAST. THE LAST HALF OF THE WEEKEND LOOKS
DRY AT THIS TIME.
NLISTEMAA
AVIATION...
00Z UPDATE...
VFR THIS EVENING BUT MVFR CIGS EXPECTED TO DEVELOP QUICKLY AROUND
05-06Z...WITH IFR BY 08-09Z. SOME POTENTIAL FOR LIFR CIGS BUT
CONFIDENCE LOW AT THIS TIME. MVFR VSBY EXPECTED AS WELL. -SHRA
MOVES IN MID-MORNING WITH LOW CHANCE FOR THUNDER AS CIGS LIFT BACK
TO MVFR...THEN WENT PREVAILING TSRA AFTER 18Z WITH LOW VFR CIGS.
EXPECT MVFR TO MOVE BACK IN AFTER 00Z TUESDAY BUT DID NOT HAVE
ROOM TO INCLUDE THAT WITH THIS SET. SSW WINDS DECREASE TO AROUND
5KT OR SLIGHTLY LOWER OVERNIGHT AND BACK BRIEFLY TO SSE THROUGH
THE MORNING. EXPECT A SHIFT BACK TO SSW AFTER THE FRONT MOVES
THROUGH...WHICH IS AFTER THE END OF THIS PERIOD.
//ATL CONFIDENCE...00Z UPDATE...
HIGH ON GENERAL TREND AND TIMING OF CIGS.
MEDIUM ON CIGS DEVELOPING BELOW 500FT AND VSBY.
MEDIUM ON TIMING OF TSRA AND WIND SHIFT BACK TO SSW AT 18Z.
TDP
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 53 65 50 65 / 40 90 90 10
ATLANTA 56 69 49 62 / 40 90 90 10
BLAIRSVILLE 51 59 43 55 / 40 90 90 10
CARTERSVILLE 55 68 48 62 / 40 90 90 10
COLUMBUS 56 72 56 68 / 30 80 60 10
GAINESVILLE 53 62 48 62 / 40 90 90 10
MACON 54 70 55 69 / 30 80 60 20
ROME 56 69 46 62 / 50 90 90 10
PEACHTREE CITY 52 69 51 64 / 40 80 80 10
VIDALIA 56 75 62 71 / 20 60 50 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1010 AM EDT SAT MAR 16 2013
...RED FLAG WARNING TODAY -- HIGH FIRE DANGER ACROSS SOUTHEAST
SOUTH CAROLINA AND SOUTHEAST GEORGIA...
.SYNOPSIS...
HIGH PRESSURE WILL PREVAIL INTO EARLY NEXT WEEK. A COLD FRONT WILL
THEN MOVE THROUGH THE AREA TUESDAY...FOLLOWED BY BRIEF HIGH
PRESSURE THROUGH WEDNESDAY. EXPECT A WETTER STORM SYSTEM TO THEN
AFFECT THE AREA THURSDAY AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE FORECAST ONLY REQUIRED MINOR ADJUSTMENTS WITH THE LATE MORNING
UPDATE CYCLE. ELONGATED SURFACE HIGH PRESSURE WILL REMAIN ANCHORED
OVER SOUTHERN FLORIDA TODAY WITH SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA REMAINING ON ITS NORTHERN PERIPHERY. IT WILL BE
A VERY WARM AND BREEZY TO WINDY DAY WITH A TIGHT PRESSURE GRADIENT
SUPPORTING WINDS OF 15-25 MPH WITH GUSTS TO 35 MPH...EXCEPT 20-30
MPH WITH GUSTS TO 40 MPH ROUGHLY ALONG AND NORTH OF AN ALLENDALE-
WALTERBORO-CHARLESTON LINE. EXPANDED THE WIND ADVISORY WEST TO
INCLUDE ALLENDALE AND HAMPTON COUNTIES PER CURRENT RAP MIXING
PROFILES. A WIND ADVISORY IS NOW IN EFFECT FOR ALLENDALE-HAMPTON-
INLAND COLLETON-DORCHESTER-INLAND BERKELEY-TIDAL BERKELEY AND
CHARLESTON UNTIL 7 PM. MAY HAVE TO EXPAND THE ADVISORY SOUTH
LATER ONCE WIND GUST TRENDS BECOME MORE APPARENT.
LOW-LEVEL THICKNESSES AND BUFR SOUNDINGS SUPPORT HIGHS IN THE
UPPER 70S TO NEAR 80 MOST AREAS AWAY FROM THE IMMEDIATE COAST.
BEACH LOCATIONS WILL ONCE AGAIN HAVE A HARD TIME WARMING MUCH PAST
THE LOWER 60S GIVEN THE CHILLY SHELF WATERS THAT ARE IN PLACE.
SATELLITE SHOWS THIN CIRRUS QUICKLY THINNING SO EXPECT SUNNY SKIES
TO DOMINATE THROUGH SUNSET.
GOES-EAST RAPID SCAN OPERATIONS ARE IN EFFECT UNTIL 2344Z FOR
WILDFIRE/SMOKE MONITORING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
TONIGHT...A BACKDOOR COLD FRONT WILL SLOWLY SAG ACROSS THE
SOUTHERN MID-ATLANTIC REGION...WHILE HIGH PRESSURE PREVAILS JUST
NORTHEAST OF THE BAHAMAS. THIS WILL SUPPORT A CONTINUED TIGHT
SURFACE PRESSURE GRADIENT OVER THE AREA IN THE EVENING...WITH THE
GRADIENT EXPECTED TO RELAX SOME OVERNIGHT. THE ATMOSPHERE WILL
REMAIN FAIRLY WELL MIXED IN THE EVENING...BUT WIND SPEEDS SHOULD
LIGHTEN AND POSSIBLY EVEN DECOUPLE IN SOME PLACES LATER TONIGHT AS
LOW LEVEL JETTING WEAKENS OVERHEAD AND THE GRADIENT DIMINISHES.
THERE WILL BE SOME CIRRUS PASSING OVERHEAD AT TIMES...AND MODELS ARE
INDICATING THAT BOUNDARY LAYER MOISTURE WILL INCREASE TOWARD
DAYBREAK. THIS COULD LEAD TO THE DEVELOPMENT OF SOME PATCHY FOG
WHERE WINDS DECOUPLE...MAINLY ACROSS PARTS OF SOUTHEAST GEORGIA.
LOWS WILL GENERALLY BE IN THE LOWER TO MID 50S TONIGHT.
SUNDAY THROUGH TUESDAY...FAIRLY ZONAL FLOW ALOFT TO START THE
PERIOD WILL BACK TO MORE SOUTHWESTERLY AHEAD OF AN UPPER TROUGH
WHICH LOOKS TO ENVELOPE MUCH OF THE EASTERN US BY THE END OF THE
PERIOD. AHEAD OF THIS TROUGH A STATIONARY FRONT WILL LINGER JUST
NORTH OF THE AREA UNTIL MONDAY WHEN IT SHOULD RETREAT BACK NORTH
AS A WARM FRONT. A COLD FRONT WILL THEN PUSH THROUGH FROM THE WEST
LATE MONDAY NIGHT INTO TUESDAY MORNING. RAIN SHOULD HOLD OFF
THROUGH SUNDAY NIGHT WITH BETTER CHANCES MONDAY INTO MONDAY NIGHT.
THERE LOOKS LIKE THERE COULD BE ENOUGH INSTABILITY...BOTH IN THE
LOWER AND MID LEVELS...TO PRODUCE SOME THUNDERSTORMS. A FEW
SHOWERS COULD LINGER NEAR THE COAST TUESDAY MORNING BEFORE MUCH
DRIER AIR FILTERS IN FROM THE WEST DURING THE DAY. RAINFALL TOTALS
THROUGH THE PERIOD SHOULD BE 0.25 INCHES OR LESS...HIGHEST LIKELY
INLAND CLOSER TO THE FRONT. FAIRLY WARM CONDITIONS ARE EXPECTED
THROUGH THE PERIOD WITH HIGHS IN THE MID TO UPPER 70S...WELL ABOVE
NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
HIGH PRESSURE WILL MOVE INTO THE AREA TUESDAY NIGHT BEFORE WEAKENING
WEDNESDAY AS ANOTHER TROUGH SHIFTS OFF THE MID ATLANTIC COAST. HIGH
PRESSURE WILL THEN BE REINFORCED FROM THE NORTHWEST WEDNESDAY NIGHT.
FORECAST UNCERTAINTY GROWS THURSDAY AS THERE IS SOME MODEL
DISAGREEMENT REGARDING HOW QUICK DEEP MOISTURE BEGINS TO MOVE BACK
IN FROM THE WEST IN ASSOCIATION WITH DEVELOPING LOW PRESSURE OVER
THE PLAINS. FOR NOW WILL KEEP IT DRY UNTIL THURSDAY WHEN DEEPER
MOISTURE MOVES IN AND LOW PRESSURE DEVELOPS ALONG A WARM FRONT NEAR
THE GULF COAST AND TRACKS TOWARD THE AREA. GOOD RAIN CHANCES SHOULD
PERSIST THROUGH FRIDAY BEFORE THE DEEPER MOISTURE SHIFTS OFFSHORE.
WITH PWATS SURPASSING 1.5 INCHES WE COULD SEE A HEALTHY DOSE OF
RAINFALL FROM THIS EVENT WITH TOTALS 1.5-2 INCHES.
TEMPERATURES WILL BE CLOSE TO NORMAL WEDNESDAY AND THEN LIKELY BELOW
NORMAL THURSDAY THROUGH THE END OF THE WEEK.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 12Z SUNDAY.
40-45 KT WINDS WITHIN A COUPLE THOUSAND FEET OF THE SURFACE WILL
RESULT IN LOW LEVEL WIND SHEAR AT BOTH TERMINALS THROUGH MID-
MORNING. THEN...AS DEEPER MIXING DEVELOPS IN THE LATE MORNING AND
AFTERNOON...WIND GUSTS WILL REACH UPWARDS OF 30-35 KT AT KCHS AND
25-30 KT AT KSAV.
EXTENDED AVIATION OUTLOOK...LOW PROBABILITY OF MVFR CONDITIONS
WITH SHOWERS MONDAY INTO TUESDAY WITH A COLD FRONT.
&&
.MARINE...
SATURDAY....THE REGION WILL BE UNDER THE INFLUENCE OF AN
INCREASING PRESSURE GRADIENT AND STRENGTHENING WINDS AS AN AREA OF
LOW PRESSURE MOVES ACROSS THE MID ATLANTIC STATES AND HIGHER
PRESSURE REMAINS SOUTH OF THE AREA ACROSS FLORIDA AND THE ADJACENT
ATLANTIC WATERS. SOUTHWEST WINDS OF GENERALLY 15 TO 20 KT WITH
GUSTS OF 20 TO 25 KT WILL BE POSSIBLE. HAVE ISSUED A SMALL CRAFT
ADVISORY FOR THE CHARLESTON HARBOR AND THE NEAR SHORE SOUTH
CAROLINA WATERS NORTH OF EDISTO BEACH...ALTHOUGH THE STRONGEST
GUSTS THERE WILL OCCUR WELL OUT TOWARD 20 NM FROM THE COAST WHERE
WARMER WATER TEMPERATURES WILL PROMOTE STRONGER MIXING.
SATURDAY NIGHT...WINDS WILL REMAIN ELEVATED INTO THE EVENING...BUT
SHOULD BEGIN TO DIMINISH IN THE LATE EVENING AND OVERNIGHT AS THE
SURFACE PRESSURE GRADIENT WEAKENS AND LOW LEVEL WINDS SUBSIDE. THE
SMALL CRAFT ADVISORY IS SCHEDULED TO COME DOWN AT 8 PM FOR
CHARLESTON HARBOR AND MIDNIGHT FOR THE NEAR SHORE WATERS NORTH OF
EDISTO BEACH.
SUNDAY THROUGH THURSDAY...THE PATTERN WILL BE DOMINATED BY ATLANTIC
HIGH PRESSURE INTO MONDAY NIGHT BEFORE A COLD FRONT PUSHES THROUGH
EARLY TUESDAY. HIGH PRESSURE WILL THEN MOVE IN THROUGH WEDNESDAY
BEFORE ANOTHER COLD FRONT PUSHES THROUGH WEDNESDAY NIGHT. THERE WILL
BE A CHANCE OF ADVISORY CONDITIONS IN CHARLESTON HARBOR MON AND TUE
DUE TO BREEZY CONDITIONS ALONG THE LAND/SEA INTERFACE BUT OTHERWISE
CONDITIONS SHOULD MOSTLY REMAIN BELOW ADVISORY LEVELS.
&&
.FIRE WEATHER...
DATA CONTINUES TO SUPPORT GUSTY WINDS OF 15-25 MPH WITH GUSTS TO
30-35 MPH AND LOW HUMIDITY OF 20-25 PERCENT INLAND AND 25-35
PERCENT CLOSE TO THE COAST THIS AFTERNOON/EARLY EVENING. STATE AND
FEDERAL USERS INDICATE THAT FUELS HAVE DRIED OUT CONSIDERABLY OVER
THE PAST FEW DAYS...SO CONDITIONS ARE BECOMING MORE FAVORABLE FOR
WILDFIRES. A RED FLAG WARNING REMAINS IN EFFECT FOR ALL FIRE
ZONES UNTIL 7 PM.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...RED FLAG WARNING UNTIL 7 PM EDT THIS EVENING FOR GAZ087-088-
099>101-114>119-137>141.
SC...RED FLAG WARNING UNTIL 7 PM EDT THIS EVENING FOR SCZ040-
042>045-047>052.
WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR SCZ040-042>045-
050-052.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR AMZ350.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR AMZ330.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1000 PM CDT SUN MAR 17 2013
.DISCUSSION...
838 PM CDT
UPDATE FOR REST OF TONIGHT...MINIMAL TWEAKING OF GRIDS DONE
OTHERWISE NO CHANGE TO FORECAST. BESIDES 21Z SREF AN RAP RUNS...
WHICH SUPPORT GOING FORECAST...NO NEW MODEL OUTPUT YET TO SEE IF
ANY SIGNIFICANT DEVIATIONS FROM EARLIER RUNS SO NO CHANGES MADE
AT THIS TIME.
TRS
//PREV DISCUSSION...
315 PM CDT
THE FORECAST CHALLENGES REMAIN FIRST ON THE LIKELIHOOD FOR SOME
LIGHT WINTRY PRECIP IN PLACES TONIGHT AND THEN LIGHT SNOW
ACCUMULATIONS ACROSS FAR NORTHERN ILLINOIS ON MONDAY...FOLLOWED BY
WHAT WILL BECOME THE BIG STORY AND THAT IS WELL BELOW NORMAL
TEMPERATURES FROM TUESDAY THROUGH THE END OF THE WORKWEEK.
SYNOPSIS...THE POLAR VORTEX OVER HUDSON BAY DURING MUCH OF LAST
WEEK HAS SHIFTED EAST...TEMPORARILY...ALLOWING FOR A FASTER PACED
DISTURBED FLOW TO HAVE EVOLVED INTO THE MIDDLE OF THE COUNTRY
TODAY. ONE SHORT WAVE IMPULSE OVER THE OZARKS THIS AFTERNOON IS
MOVING NORTHEAST SPREADING A VEIL OF HIGH CLOUDS ACROSS PART OF
THE AREA. THIS WILL BE THE SYSTEM TO BRING LIGHT PRECIP LATER
TONIGHT AS IT CONTINUES ALONG ITS TRACK. FURTHER WEST...A WELL-
DEFINED UPPER LEVEL JET IS MOVING EAST ACROSS THE WESTERN CONUS
AND USHERING A PRONOUNCED UPPER WAVE ACROSS EASTERN WY THIS
AFTERNOON. THIS WILL BE THE MONDAY MORNING INTO EARLY AFTERNOON
PRECIP MAKER AND BRING A POWERFUL COLD FRONT THROUGH MONDAY
EVE. THIS SYSTEM WILL CATCH UP WITH ITS PREDECESSOR ALLOWING
PHASING AND AN OVERALL IMPRESSIVE SYSTEM DEEPENING AND ORGANIZATION
OVER THE GREAT LAKES MONDAY NIGHT INTO TUESDAY. A MASSIVE
ANOMALOUSLY DEEP CLOSED UPPER LOW WILL BE THE RESULT. WITH FURTHER
BLOCKING UPSTREAM OVER THE NORTH ATLANTIC...THIS WILL MOVE LITTLE
THUS SUSTAINING NORTHWEST FLOW OVER THE REGION WITH REGULAR
REINFORCING SHOTS OF REALLY COLD AIR BY MARCH STANDARDS.
TONIGHT...MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THE SHORT
WAVE OVER MO MOVING NORTHEAST AND BRINGING WITH IT THE ONGOING
WARM MOIST ADVECTION ALOFT THAT HAS PRODUCED PRECIP DOWNSTATE
TODAY. MODEL DIFFERENCES REMAIN IN PRECIP TYPE WHICH CAN BE
EXPECTED WITH HOW CLOSE TO 0C A GOOD PART OF THE FORECAST THERMAL
PROFILES ARE. VARIOUS WRF AND ARW MODELS INDICATE PRECIP SHOULD
SLOWLY SPREAD NORTHWARD THROUGH CENTRAL IL THIS EVE AND FORECAST
ISENTROPIC SURFACES AND ELEVATED MOISTURE CONVERGENCE FROM BOTH
THE RAP AND NAM AGREE WITH THIS DEPICTION. SOME FLURRIES/DRIZZLE
AHEAD OF THE MAIN PRECIP AREA ARE POSSIBLE AS THE ATMOSPHERE
SATURATES.
THERE ARE SEVERAL CULPRITS FOR THE PRECIP TYPE QUESTIONS. FOR
ONE...BECAUSE THE AREA IS GRAZED BY THE LEAD SHORT WAVE AND ITS
DEEPER SATURATION...THERE IS UNCERTAINTY ON WHETHER ICE CRYSTALS
ARE INTRODUCED. SECOND...THERE IS A SEVERAL THOUSAND FT DEEP
LAYER AROUND 0C FORECAST ACROSS A LARGE PART OF THE AREA AS PRECIP
SPREADS IN. AND FINALLY...SURFACE TEMPERATURES ARE LIKELY TO HOLD
STEADY THROUGH LATE EVE AND OVERNIGHT...AND MAY EVEN INCH UP IN
THE FAR SOUTH DEPENDING ON PRECIP STRENGTH...WHICH PRIMARILY LOOKS
LIGHT.
WHILE THERE MAY BE LIGHT SNOW IN THE ONSET SOUTH OF I-80 THIS EVE
AS THE WARM NOSE IS MARGINAL...IT APPEARS THAT BY OVERNIGHT THIS
LAYER WILL BE DEEP ENOUGH TO SUPPORT FULL MELTING. THE MOISTURE
TRANSPORT NOSE FROM THE SHORT WAVE POINTS INTO THE SOUTHEAST
FORECAST AREA...AND DO HAVE AROUND ONE TENTH OF AN INCH OF QPF.
SURFACE TEMPERATURES LOOK TO BE JUST ABOVE FREEZING THERE...BUT
WILL NEED TO BE WATCHED CLOSELY. FURTHER TO THE NORTH...TOWARD
I-80 AND EVEN SOMEWHAT NORTH FROM THERE...QPF LOOKS TO BE LIGHT
OVERNIGHT...BUT PROFILES DO SUPPORT LIGHT FREEZING RAIN OR SLEET
DEPENDING ON WHICH MODEL. THIS DOES INCLUDE FOR DOWNTOWN CHICAGO.
TOWARD FAR NORTHERN IL...THE PROFILES BECOME COOL ENOUGH THAT THE
TYPE SHOULD BE SLEET OR SNOW...BUT AGAIN PRIOR TO DAYBREAK THIS
LOOKS TO BE LIGHT.
AS THE MAIN UPPER WAVE APPROACHES MONDAY MORNING...GUIDANCE
AGREES ON THIS BEING THE STRONGEST PERIOD OF OMEGA/QG FORCING FOR
THE NORTHERN AREA. BECAUSE OF THIS FORCING AND THE ALREADY VERY
MARGINAL PROFILES FOR ANYTHING BUT SNOW THAT FAR NORTH...PRECIP
TYPE LOOKS TO TRANSITION TO A WET SNOW. THE HIGHER RATES SHOULD BE
TO THE NORTH OF THE CWA BUT ENOUGH SUPPORT WITH 31F-33F SURFACE
TEMPERATURES TO SUPPORT UP TO A COUPLE INCHES OF SNOW NEAR THE WI
BORDER. THE BEST TIMING FOR CHICAGO LOOKS TO BE FROM MID TO LATE
MORNING INTO EARLY AFTERNOON...WITH A DUSTING SOUTH TO ONE TO TWO
INCHES IN THE NORTH. STRONG DRYING IN THE MID-LEVELS IS FORECAST
TO FLOOD OVER THE AREA DURING THE AFTERNOON...CUTTING OFF MOST OF
THE FORCING FOR PRECIP. THIS WILL ALLOW TEMPERATURES TO MODERATE
ACROSS MUCH OF THE AREA BEFORE THE INCOMING PLUNGE...AND ITS
POSSIBLE MID 40S ARE REACHED SOUTH OF I-80 DEPENDING ON DEGREE OF
SCATTERING.
BY EARLY MONDAY EVE THE SYSTEMS COLD FRONT WILL BE SWEEPING ACROSS
NORTH CENTRAL IL. THE TEMPERATURE DROP LOOKS TO BE SHARP FOR THE
FIRST COUPLE HOURS AFTER THE FRONT AND HAVE TRIED TO MASSAGE SOME
OF THAT INTO THE HOURLY FORECAST GRIDS GIVEN THE HIGH CONFIDENCE
ALREADY. WITH THE MIXED BOUNDARY LAYER AND STRONG ISALLOBARIC
COMPONENT FORECAST...WINDS LOOK TO BE GUSTING TO 30 AND MAYBE EVEN
40 MPH /ESPECIALLY RIGHT AFTER FROPA/. THE CIPS ANALOG GUIDANCE
DOES HAVE A MAJORITY OF ITS MATCHES FAVORING GUSTS THAT HIGH IN
THE REGION. WIND CHILLS ARE EXPECTED TO FREE FALL INTO THE SINGLE
DIGITS BY MID EVE...AND THEN BELOW ZERO IN NORTHERN AREAS
OVERNIGHT. AS THE UPPER LOW MOVES ACROSS WI...ITS SOUTHERN FLANK
OF MID-LEVEL COLD AIR ADVECTION AND WRAPAROUND LOW-LEVEL MOISTURE
MAY BE ENOUGH TO SUPPORT FLURRIES OR EVEN SHOW SHOWERS. WHILE THIS
WILL BE LIGHT GIVEN LIMITED OVERALL FORCING...WITH THE GUSTY WINDS
AND THE LOWERING WATER CONTENT OF THE SNOW...THERE MAY BE SOME
MARKEDLY REDUCED VISIBILITIES IF AND WHERE SOME OF THIS SNOW
IS ABLE MATERIALIZE ACROSS FAR NORTHERN IL MONDAY EVE.
FOR TUESDAY AND BEYOND...THE COLD AIR ADVECTION CONTINUES TO
REINFORCE ITSELF WITH MULTIPLE COLD FRONTS AND MASSIVE CYCLONIC
FLOW. THIS FLOW WILL KEEP THE POTENTIAL FOR AT LEAST
STRATOCU...ALONG WITH THE CHANCE FOR SNOW SHOWERS.
HOWEVER...TEMPERATURES WERE THE FOCUS...AND THEY LOOK TO BE
REMARKABLY LOW FOR THE LATTER HALF OF MARCH. 850MB TEMPERATURES
ARE FORECAST TO DROP TO AROUND -15C TUE MORNING AND THEN AGAIN WED
MORNING. THE SURFACE WIND COMPONENT REMAINS ELEVATED THROUGH
WED...BUT STILL NIGHTTIME TEMPERATURES WILL FALL INTO THE TEENS
AREA WIDE THANKS TO THE COLD AIR ADVECTION. HIGHS WILL NOT REBOUND
MUCH...AND IN SOME PLACES WILL REMAIN BELOW 30F ON WEDNESDAY. IN
FACT...THE LOW MAXIMUM TEMPERATURE RECORD FOR WED IN ROCKFORD OF
ONLY 22F LOOKS TO BE POTENTIALLY IN JEOPARDY. THE SURFACE
HIGH BUILDS IN LATER THU THROUGH THE EARLY PART OF THE WEEKEND.
WITH THE BLOCKED FLOW...THE COLD AIR MASS HAS NO WHERE TO GO BUT
REINFORCE ITSELF FROM THE NORTH. AND ON THAT NOTE...BACKWARDS
TRAJECTORIES FROM THE GFS FOR WED INDICATE PARCELS ORIGINATING FROM
60 DEGREES NORTH LATITUDE /THE BORDER OF THE NORTHERN AND
SOUTHERN CANADIAN PROVINCES/. ALSO CONSIDERING THE EXTENT OF THE
SNOW COVER TO OUR NORTHWEST...WHICH WILL EXPAND TONIGHT INTO
MONDAY...LITTLE AIR MASS MODIFICATION IS ABLE TO OCCUR.
QUITE FASCINATING FOR LATE MARCH!
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* TIMING/TYPE OF PRECIPITATION LATE TONIGHT/MONDAY...MIXED PRECIP
LIKELY.
* MVFR/IFR CONDITIONS DEVELOPING MONDAY MORNING.
* GUSTY EAST WINDS NEAR 20 KT OVERNIGHT...DIMINISHING AND BECOMING
WEST-SOUTHWEST MIDDAY MONDAY AND INCREASING TO 20-30 KT BY
MONDAY EVENING.
RATZER
//DISCUSSION...UPDATED 00Z...
QUITE A BIT OF WEATHER GOING ON DURING THE 24-30 HOUR FORECAST
PERIOD.
HIGH PRESSURE OVER THE EASTERN GREAT LAKES REGION WILL DRIFT EAST
ACROSS NEW ENGLAND BY EARLY MONDAY MORNING...WHILE A PAIR OF LOW
PRESSURE SYSTEMS MOVE INTO THE UPPER MIDWEST AND LOWER OHIO VALLEY
REGIONS. COOL...DRY EAST SFC FLOW WILL REMAIN IN PLACE ACROSS THE
TERMINALS MUCH OF TONIGHT...WHILE WARM/MOIST AIR SPREADS IN ALOFT
AS AN UPPER LEVEL DISTURBANCE APPROACHES. THIS IS EXPECTED TO
LEAD TO SATURATION AND PRECIPITATION DEVELOPMENT FROM THE SOUTH-
SOUTHWEST BY SUNRISE MONDAY. FORECAST THERMAL PROFILES FROM
VARIOUS MODELS INDICATE TEMPERATURES NEAR/SLIGHTLY ABOVE FREEZING
IN THE LOWER 5000 FT OR SO OF THE ATMOSPHERE...PRESENTING THE
LIKELIHOOD OF MIXED PRECIP ACROSS THE TERMINALS MONDAY MORNING.
THESE PROFILES SUGGEST AREAS FARTHER NORTH/NORTHWEST SHOULD SEE
MORE OF A SNOW/PSBL SLEET MIX...TRENDING MORE TOWARD RAIN/FREEZING
RAIN/SLEET WITH SLIGHTLY WARMER TEMPS ALOFT FARTHER SOUTH FOR
KMDW AND KGYY TERMINALS. SURFACE TEMPERATURES SHOULD RISE ABOVE
FREEZING IN MOST AREAS BY LATE MORNING...WITH MID-LEVEL DRY AIR
ALSO ARRIVING AND RESULTING IN A DECREASE IN PRECIPITATION
INTENSITY AND A TREND MORE TOWARD DRIZZLE. IT APPEARS THAT IFR
CONDITIONS ARE FAIRLY LIKELY IF DEEP SATURATION/PRECIP INDICATED
BY MODEL FORECASTS DOES INDEED OCCUR...THUS THE MORNING THROUGH
MIDDAY HOURS LOOK TO BE THE MOST CHALLENGING WITH MIXED PRECIP AND
IFR CIG/VIS CONDITIONS. IFR CIGS/FOG MAY LINGER A FEW HOURS INTO
EARLY AFTERNOON...BEFORE IMPROVING QUICKLY DURING THE AFTERNOON.
THE MAIN SURFACE LOW WILL PASS WELL NORTH OF THE AREA DURING THE
DAY...WITH A SURFACE TROUGH EXTENDING SOUTHEAST THROUGH THE AREA
TO THE WEAKER SOUTHERN LOW. WINDS WILL START OUT BRISK EASTERLY...
BUT WILL DIMINISH AND VEER TO THE WEST-SOUTHWEST AS THE SURFACE
TROUGH AXIS MOVES ACROSS THE TERMINALS MIDDAY. WEST-SOUTHWEST
WINDS WILL THEN INCREASE SIGNIFICANTLY BY LATE AFTERNOON AND
EVENING...AS COLDER AIR BEGINS TO WRAP IN FROM THE WEST. THIS WILL
RESULT IN LOW LEVEL LAPSE RATES STEEPENING SHARPLY...WITH WINDS
INCREASING INTO THE 20-30 KT RANGE FROM THE WEST BY EVENING. THIS
WILL ALSO LIKELY RESULT IN AN MVFR STRATOCU LAYER DEVELOPING IN
THE 2000 FT AGL RANGE...WITH A PERIOD OF CONVECTIVE SNOW
SHOWERS/FLURRIES POSSIBLE DURING THE EVENING.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE IN WIND TRENDS.
* MEDIUM CONFIDENCE IN TIMING/TRENDS AND TYPE OF PRECIP.
* MEDIUM CONFIDENCE IN PERIOD OF PREVAILING IFR CIG/VIS DURING
MONDAY MORNING/MIDDAY.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY THROUGH SATURDAY...MAINLY VFR. GUSTY WEST WINDS TUE.
RATZER
&&
.MARINE...
233 PM CDT
MAIN CONCERN FOR THE MARINE FORECAST WILL BE PERIOD OF GALES
POSSIBLE MONDAY EVENING THROUGH LATE TUESDAY. TODAY...HIGH PRESSURE
IS CENTERED OVER THE GREAT LAKES REGION PROVIDING DIMINISHING
EAST/NORTHEAST FLOW ACROSS LAKE MICHIGAN. TWO AREAS OF LOW PRESSURE
ARE TAKING SHAPE...ONE ACROSS THE NORTHERN ROCKIES AND THE SECOND
OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THE NORTHERN LOW
IS EXPECTED TO MOVE EAST INTO MINNESOTA TONIGHT WITH WINDS OVER THE
LAKE BECOMING SOUTHEAST AND INCREASING INTO THE 20 TO 25 KT POSSIBLY
30 KT RANGE. THE GRADIENT AHEAD OF THE LOW THEN QUICKLY DIMINISHES
MONDAY AS THE LOW MOVES INTO WISCONSIN AND BROAD TROUGHING TAKES
PLACES ACROSS LAKE MICHIGAN BETWEEN THE NORTHERN LOW...AND THE
SOUTHERN LOW AS IT MOVES INTO THE SOUTHERN APPALACHIANS. THIS SHOULD
ALLOW WINDS TO DIMINISH FOR A SHORT PERIOD DURING THE DAY MONDAY
BEFORE WINDS TURN SOUTHWEST...THEN WEST AND QUICKLY INCREASE AGAIN
AS THE NORTHERN LOW MOVES EAST OF LAKE MICHIGAN. WITH THE GRADIENT
QUICKLY STRENGTHENS AND STRONG HEIGHT RISES MOVING IN BEHIND THE
DEPARTING LOW...GALES ARE EXPECTED ACROSS PORTIONS OF LAKE MICHIGAN.
CURRENTLY...THE BEST CHANCES FOR GALES APPEAR ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE LAKE...WITH THE GRADIENT SLIGHTLY WEAKER
ACROSS FAR NORTHERN LAKE MICHIGAN CLOSER TO THE LOW TRACK. WILL
ISSUE A GALE WATCH FOR THESE AREAS MONDAY EVENING THROUGH TUESDAY
EVENING. WINDS REMAIN ELEVATED AROUND 30 KT THROUGH THE DAY
WEDNESDAY BEFORE GRADUALLY TAPERING LATE IN THE WEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
GALE WATCH...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WATCH...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
838 PM CDT SUN MAR 17 2013
.DISCUSSION...
838 PM CDT
UPDATE FOR REST OF TONIGHT...MINIMAL TWEAKING OF GRIDS DONE
OTHERWISE NO CHANGE TO FORECAST. BESIDES 21Z SREF AN RAP RUNS...
WHICH SUPPORT GOING FORECAST...NO NEW MODEL OUTPUT YET TO SEE IF
ANY SIGNIFICANT DEVIATIONS FROM EARLIER RUNS SO NO CHANGES MADE
AT THIS TIME.
TRS
&&
.PREV DISCUSSION...
315 PM CDT
THE FORECAST CHALLENGES REMAIN FIRST ON THE LIKELIHOOD FOR SOME
LIGHT WINTRY PRECIP IN PLACES TONIGHT AND THEN LIGHT SNOW
ACCUMULATIONS ACROSS FAR NORTHERN ILLINOIS ON MONDAY...FOLLOWED BY
WHAT WILL BECOME THE BIG STORY AND THAT IS WELL BELOW NORMAL
TEMPERATURES FROM TUESDAY THROUGH THE END OF THE WORKWEEK.
SYNOPSIS...THE POLAR VORTEX OVER HUDSON BAY DURING MUCH OF LAST
WEEK HAS SHIFTED EAST...TEMPORARILY...ALLOWING FOR A FASTER PACED
DISTURBED FLOW TO HAVE EVOLVED INTO THE MIDDLE OF THE COUNTRY
TODAY. ONE SHORT WAVE IMPULSE OVER THE OZARKS THIS AFTERNOON IS
MOVING NORTHEAST SPREADING A VEIL OF HIGH CLOUDS ACROSS PART OF
THE AREA. THIS WILL BE THE SYSTEM TO BRING LIGHT PRECIP LATER
TONIGHT AS IT CONTINUES ALONG ITS TRACK. FURTHER WEST...A WELL-
DEFINED UPPER LEVEL JET IS MOVING EAST ACROSS THE WESTERN CONUS
AND USHERING A PRONOUNCED UPPER WAVE ACROSS EASTERN WY THIS
AFTERNOON. THIS WILL BE THE MONDAY MORNING INTO EARLY AFTERNOON
PRECIP MAKER AND BRING A POWERFUL COLD FRONT THROUGH MONDAY
EVE. THIS SYSTEM WILL CATCH UP WITH ITS PREDECESSOR ALLOWING
PHASING AND AN OVERALL IMPRESSIVE SYSTEM DEEPENING AND ORGANIZATION
OVER THE GREAT LAKES MONDAY NIGHT INTO TUESDAY. A MASSIVE
ANOMALOUSLY DEEP CLOSED UPPER LOW WILL BE THE RESULT. WITH FURTHER
BLOCKING UPSTREAM OVER THE NORTH ATLANTIC...THIS WILL MOVE LITTLE
THUS SUSTAINING NORTHWEST FLOW OVER THE REGION WITH REGULAR
REINFORCING SHOTS OF REALLY COLD AIR BY MARCH STANDARDS.
TONIGHT...MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THE SHORT
WAVE OVER MO MOVING NORTHEAST AND BRINGING WITH IT THE ONGOING
WARM MOIST ADVECTION ALOFT THAT HAS PRODUCED PRECIP DOWNSTATE
TODAY. MODEL DIFFERENCES REMAIN IN PRECIP TYPE WHICH CAN BE
EXPECTED WITH HOW CLOSE TO 0C A GOOD PART OF THE FORECAST THERMAL
PROFILES ARE. VARIOUS WRF AND ARW MODELS INDICATE PRECIP SHOULD
SLOWLY SPREAD NORTHWARD THROUGH CENTRAL IL THIS EVE AND FORECAST
ISENTROPIC SURFACES AND ELEVATED MOISTURE CONVERGENCE FROM BOTH
THE RAP AND NAM AGREE WITH THIS DEPICTION. SOME FLURRIES/DRIZZLE
AHEAD OF THE MAIN PRECIP AREA ARE POSSIBLE AS THE ATMOSPHERE
SATURATES.
THERE ARE SEVERAL CULPRITS FOR THE PRECIP TYPE QUESTIONS. FOR
ONE...BECAUSE THE AREA IS GRAZED BY THE LEAD SHORT WAVE AND ITS
DEEPER SATURATION...THERE IS UNCERTAINTY ON WHETHER ICE CRYSTALS
ARE INTRODUCED. SECOND...THERE IS A SEVERAL THOUSAND FT DEEP
LAYER AROUND 0C FORECAST ACROSS A LARGE PART OF THE AREA AS PRECIP
SPREADS IN. AND FINALLY...SURFACE TEMPERATURES ARE LIKELY TO HOLD
STEADY THROUGH LATE EVE AND OVERNIGHT...AND MAY EVEN INCH UP IN
THE FAR SOUTH DEPENDING ON PRECIP STRENGTH...WHICH PRIMARILY LOOKS
LIGHT.
WHILE THERE MAY BE LIGHT SNOW IN THE ONSET SOUTH OF I-80 THIS EVE
AS THE WARM NOSE IS MARGINAL...IT APPEARS THAT BY OVERNIGHT THIS
LAYER WILL BE DEEP ENOUGH TO SUPPORT FULL MELTING. THE MOISTURE
TRANSPORT NOSE FROM THE SHORT WAVE POINTS INTO THE SOUTHEAST
FORECAST AREA...AND DO HAVE AROUND ONE TENTH OF AN INCH OF QPF.
SURFACE TEMPERATURES LOOK TO BE JUST ABOVE FREEZING THERE...BUT
WILL NEED TO BE WATCHED CLOSELY. FURTHER TO THE NORTH...TOWARD
I-80 AND EVEN SOMEWHAT NORTH FROM THERE...QPF LOOKS TO BE LIGHT
OVERNIGHT...BUT PROFILES DO SUPPORT LIGHT FREEZING RAIN OR SLEET
DEPENDING ON WHICH MODEL. THIS DOES INCLUDE FOR DOWNTOWN CHICAGO.
TOWARD FAR NORTHERN IL...THE PROFILES BECOME COOL ENOUGH THAT THE
TYPE SHOULD BE SLEET OR SNOW...BUT AGAIN PRIOR TO DAYBREAK THIS
LOOKS TO BE LIGHT.
AS THE MAIN UPPER WAVE APPROACHES MONDAY MORNING...GUIDANCE
AGREES ON THIS BEING THE STRONGEST PERIOD OF OMEGA/QG FORCING FOR
THE NORTHERN AREA. BECAUSE OF THIS FORCING AND THE ALREADY VERY
MARGINAL PROFILES FOR ANYTHING BUT SNOW THAT FAR NORTH...PRECIP
TYPE LOOKS TO TRANSITION TO A WET SNOW. THE HIGHER RATES SHOULD BE
TO THE NORTH OF THE CWA BUT ENOUGH SUPPORT WITH 31F-33F SURFACE
TEMPERATURES TO SUPPORT UP TO A COUPLE INCHES OF SNOW NEAR THE WI
BORDER. THE BEST TIMING FOR CHICAGO LOOKS TO BE FROM MID TO LATE
MORNING INTO EARLY AFTERNOON...WITH A DUSTING SOUTH TO ONE TO TWO
INCHES IN THE NORTH. STRONG DRYING IN THE MID-LEVELS IS FORECAST
TO FLOOD OVER THE AREA DURING THE AFTERNOON...CUTTING OFF MOST OF
THE FORCING FOR PRECIP. THIS WILL ALLOW TEMPERATURES TO MODERATE
ACROSS MUCH OF THE AREA BEFORE THE INCOMING PLUNGE...AND ITS
POSSIBLE MID 40S ARE REACHED SOUTH OF I-80 DEPENDING ON DEGREE OF
SCATTERING.
BY EARLY MONDAY EVE THE SYSTEMS COLD FRONT WILL BE SWEEPING ACROSS
NORTH CENTRAL IL. THE TEMPERATURE DROP LOOKS TO BE SHARP FOR THE
FIRST COUPLE HOURS AFTER THE FRONT AND HAVE TRIED TO MASSAGE SOME
OF THAT INTO THE HOURLY FORECAST GRIDS GIVEN THE HIGH CONFIDENCE
ALREADY. WITH THE MIXED BOUNDARY LAYER AND STRONG ISALLOBARIC
COMPONENT FORECAST...WINDS LOOK TO BE GUSTING TO 30 AND MAYBE EVEN
40 MPH /ESPECIALLY RIGHT AFTER FROPA/. THE CIPS ANALOG GUIDANCE
DOES HAVE A MAJORITY OF ITS MATCHES FAVORING GUSTS THAT HIGH IN
THE REGION. WIND CHILLS ARE EXPECTED TO FREE FALL INTO THE SINGLE
DIGITS BY MID EVE...AND THEN BELOW ZERO IN NORTHERN AREAS
OVERNIGHT. AS THE UPPER LOW MOVES ACROSS WI...ITS SOUTHERN FLANK
OF MID-LEVEL COLD AIR ADVECTION AND WRAPAROUND LOW-LEVEL MOISTURE
MAY BE ENOUGH TO SUPPORT FLURRIES OR EVEN SHOW SHOWERS. WHILE THIS
WILL BE LIGHT GIVEN LIMITED OVERALL FORCING...WITH THE GUSTY WINDS
AND THE LOWERING WATER CONTENT OF THE SNOW...THERE MAY BE SOME
MARKEDLY REDUCED VISIBILITIES IF AND WHERE SOME OF THIS SNOW
IS ABLE MATERIALIZE ACROSS FAR NORTHERN IL MONDAY EVE.
FOR TUESDAY AND BEYOND...THE COLD AIR ADVECTION CONTINUES TO
REINFORCE ITSELF WITH MULTIPLE COLD FRONTS AND MASSIVE CYCLONIC
FLOW. THIS FLOW WILL KEEP THE POTENTIAL FOR AT LEAST
STRATOCU...ALONG WITH THE CHANCE FOR SNOW SHOWERS.
HOWEVER...TEMPERATURES WERE THE FOCUS...AND THEY LOOK TO BE
REMARKABLY LOW FOR THE LATTER HALF OF MARCH. 850MB TEMPERATURES
ARE FORECAST TO DROP TO AROUND -15C TUE MORNING AND THEN AGAIN WED
MORNING. THE SURFACE WIND COMPONENT REMAINS ELEVATED THROUGH
WED...BUT STILL NIGHTTIME TEMPERATURES WILL FALL INTO THE TEENS
AREA WIDE THANKS TO THE COLD AIR ADVECTION. HIGHS WILL NOT REBOUND
MUCH...AND IN SOME PLACES WILL REMAIN BELOW 30F ON WEDNESDAY. IN
FACT...THE LOW MAXIMUM TEMPERATURE RECORD FOR WED IN ROCKFORD OF
ONLY 22F LOOKS TO BE POTENTIALLY IN JEOPARDY. THE SURFACE
HIGH BUILDS IN LATER THU THROUGH THE EARLY PART OF THE WEEKEND.
WITH THE BLOCKED FLOW...THE COLD AIR MASS HAS NO WHERE TO GO BUT
REINFORCE ITSELF FROM THE NORTH. AND ON THAT NOTE...BACKWARDS
TRAJECTORIES FROM THE GFS FOR WED INDICATE PARCELS ORIGINATING FROM
60 DEGREES NORTH LATITUDE /THE BORDER OF THE NORTHERN AND
SOUTHERN CANADIAN PROVINCES/. ALSO CONSIDERING THE EXTENT OF THE
SNOW COVER TO OUR NORTHWEST...WHICH WILL EXPAND TONIGHT INTO
MONDAY...LITTLE AIR MASS MODIFICATION IS ABLE TO OCCUR.
QUITE FASCINATING FOR LATE MARCH!
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* TIMING/TYPE OF PRECIPITATION LATE TONIGHT/MONDAY...MIXED PRECIP
LIKELY.
* MVFR/IFR CONDITIONS MONDAY.
* EAST WINDS OVERNIGHT...VEERING WEST-SOUTHWEST MIDDAY MONDAY AND
INCREASING TO 20-30 KT BY MONDAY EVENING.
RATZER
//DISCUSSION...UPDATED 00Z...
QUITE A BIT OF WEATHER GOING ON DURING THE 24-30 HOUR FORECAST
PERIOD.
HIGH PRESSURE OVER THE EASTERN GREAT LAKES REGION WILL DRIFT EAST
ACROSS NEW ENGLAND BY EARLY MONDAY MORNING...WHILE A PAIR OF LOW
PRESSURE SYSTEMS MOVE INTO THE UPPER MIDWEST AND LOWER OHIO VALLEY
REGIONS. COOL...DRY EAST SFC FLOW WILL REMAIN IN PLACE ACROSS THE
TERMINALS MUCH OF TONIGHT...WHILE WARM/MOIST AIR SPREADS IN ALOFT
AS AN UPPER LEVEL DISTURBANCE APPROACHES. THIS IS EXPECTED TO
LEAD TO SATURATION AND PRECIPITATION DEVELOPMENT FROM THE SOUTH-
SOUTHWEST BY SUNRISE MONDAY. FORECAST THERMAL PROFILES FROM
VARIOUS MODELS INDICATE TEMPERATURES NEAR/SLIGHTLY ABOVE FREEZING
IN THE LOWER 5000 FT OR SO OF THE ATMOSPHERE...PRESENTING THE
LIKELIHOOD OF MIXED PRECIP ACROSS THE TERMINALS MONDAY MORNING.
THESE PROFILES SUGGEST AREAS FARTHER NORTH/NORTHWEST SHOULD SEE
MORE OF A SNOW/PSBL SLEET MIX...TRENDING MORE TOWARD RAIN/FREEZING
RAIN/SLEET WITH SLIGHTLY WARMER TEMPS ALOFT FARTHER SOUTH FOR
KMDW AND KGYY TERMINALS. SURFACE TEMPERATURES SHOULD RISE ABOVE
FREEZING IN MOST AREAS BY LATE MORNING...WITH MID-LEVEL DRY AIR
ALSO ARRIVING AND RESULTING IN A DECREASE IN PRECIPITATION
INTENSITY AND A TREND MORE TOWARD DRIZZLE. IT APPEARS THAT IFR
CONDITIONS ARE FAIRLY LIKELY IF DEEP SATURATION/PRECIP INDICATED
BY MODEL FORECASTS DOES INDEED OCCUR...THUS THE MORNING THROUGH
MIDDAY HOURS LOOK TO BE THE MOST CHALLENGING WITH MIXED PRECIP AND
IFR CIG/VIS CONDITIONS. IFR CIGS/FOG MAY LINGER A FEW HOURS INTO
EARLY AFTERNOON...BEFORE IMPROVING QUICKLY DURING THE AFTERNOON.
THE MAIN SURFACE LOW WILL PASS WELL NORTH OF THE AREA DURING THE
DAY...WITH A SURFACE TROUGH EXTENDING SOUTHEAST THROUGH THE AREA
TO THE WEAKER SOUTHERN LOW. WINDS WILL START OUT BRISK EASTERLY...
BUT WILL DIMINISH AND VEER TO THE WEST-SOUTHWEST AS THE SURFACE
TROUGH AXIS MOVES ACROSS THE TERMINALS MIDDAY. WEST-SOUTHWEST
WINDS WILL THEN INCREASE SIGNIFICANTLY BY LATE AFTERNOON AND
EVENING...AS COLDER AIR BEGINS TO WRAP IN FROM THE WEST. THIS WILL
RESULT IN LOW LEVEL LAPSE RATES STEEPENING SHARPLY...WITH WINDS
INCREASING INTO THE 20-30 KT RANGE FROM THE WEST BY EVENING. THIS
WILL ALSO LIKELY RESULT IN AN MVFR STRATOCU LAYER DEVELOPING IN
THE 2000 FT AGL RANGE...WITH A PERIOD OF CONVECTIVE SNOW
SHOWERS/FLURRIES POSSIBLE DURING THE EVENING.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE IN WIND TRENDS.
* MEDIUM CONFIDENCE IN TIMING/TRENDS AND TYPE OF PRECIP.
* MEDIUM CONFIDENCE IN PERIOD OF PREVAILING IFR CIG/VIS DURING
MONDAY MORNING/MIDDAY.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY THROUGH SATURDAY...MAINLY VFR. GUSTY WEST WINDS TUE.
RATZER
&&
.MARINE...
233 PM CDT
MAIN CONCERN FOR THE MARINE FORECAST WILL BE PERIOD OF GALES
POSSIBLE MONDAY EVENING THROUGH LATE TUESDAY. TODAY...HIGH PRESSURE
IS CENTERED OVER THE GREAT LAKES REGION PROVIDING DIMINISHING
EAST/NORTHEAST FLOW ACROSS LAKE MICHIGAN. TWO AREAS OF LOW PRESSURE
ARE TAKING SHAPE...ONE ACROSS THE NORTHERN ROCKIES AND THE SECOND
OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THE NORTHERN LOW
IS EXPECTED TO MOVE EAST INTO MINNESOTA TONIGHT WITH WINDS OVER THE
LAKE BECOMING SOUTHEAST AND INCREASING INTO THE 20 TO 25 KT POSSIBLY
30 KT RANGE. THE GRADIENT AHEAD OF THE LOW THEN QUICKLY DIMINISHES
MONDAY AS THE LOW MOVES INTO WISCONSIN AND BROAD TROUGHING TAKES
PLACES ACROSS LAKE MICHIGAN BETWEEN THE NORTHERN LOW...AND THE
SOUTHERN LOW AS IT MOVES INTO THE SOUTHERN APPALACHIANS. THIS SHOULD
ALLOW WINDS TO DIMINISH FOR A SHORT PERIOD DURING THE DAY MONDAY
BEFORE WINDS TURN SOUTHWEST...THEN WEST AND QUICKLY INCREASE AGAIN
AS THE NORTHERN LOW MOVES EAST OF LAKE MICHIGAN. WITH THE GRADIENT
QUICKLY STRENGTHENS AND STRONG HEIGHT RISES MOVING IN BEHIND THE
DEPARTING LOW...GALES ARE EXPECTED ACROSS PORTIONS OF LAKE MICHIGAN.
CURRENTLY...THE BEST CHANCES FOR GALES APPEAR ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE LAKE...WITH THE GRADIENT SLIGHTLY WEAKER
ACROSS FAR NORTHERN LAKE MICHIGAN CLOSER TO THE LOW TRACK. WILL
ISSUE A GALE WATCH FOR THESE AREAS MONDAY EVENING THROUGH TUESDAY
EVENING. WINDS REMAIN ELEVATED AROUND 30 KT THROUGH THE DAY
WEDNESDAY BEFORE GRADUALLY TAPERING LATE IN THE WEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM
MONDAY.
GALE WATCH...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WATCH...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
658 PM CDT SUN MAR 17 2013
.DISCUSSION...
315 PM CDT
THE FORECAST CHALLENGES REMAIN FIRST ON THE LIKELIHOOD FOR SOME
LIGHT WINTRY PRECIP IN PLACES TONIGHT AND THEN LIGHT SNOW
ACCUMULATIONS ACROSS FAR NORTHERN ILLINOIS ON MONDAY...FOLLOWED BY
WHAT WILL BECOME THE BIG STORY AND THAT IS WELL BELOW NORMAL
TEMPERATURES FROM TUESDAY THROUGH THE END OF THE WORKWEEK.
SYNOPSIS...THE POLAR VORTEX OVER HUDSON BAY DURING MUCH OF LAST
WEEK HAS SHIFTED EAST...TEMPORARILY...ALLOWING FOR A FASTER PACED
DISTURBED FLOW TO HAVE EVOLVED INTO THE MIDDLE OF THE COUNTRY
TODAY. ONE SHORT WAVE IMPULSE OVER THE OZARKS THIS AFTERNOON IS
MOVING NORTHEAST SPREADING A VEIL OF HIGH CLOUDS ACROSS PART OF
THE AREA. THIS WILL BE THE SYSTEM TO BRING LIGHT PRECIP LATER
TONIGHT AS IT CONTINUES ALONG ITS TRACK. FURTHER WEST...A WELL-
DEFINED UPPER LEVEL JET IS MOVING EAST ACROSS THE WESTERN CONUS
AND USHERING A PRONOUNCED UPPER WAVE ACROSS EASTERN WY THIS
AFTERNOON. THIS WILL BE THE MONDAY MORNING INTO EARLY AFTERNOON
PRECIP MAKER AND BRING A POWERFUL COLD FRONT THROUGH MONDAY
EVE. THIS SYSTEM WILL CATCH UP WITH ITS PREDECESSOR ALLOWING
PHASING AND AN OVERALL IMPRESSIVE SYSTEM DEEPENING AND ORGANIZATION
OVER THE GREAT LAKES MONDAY NIGHT INTO TUESDAY. A MASSIVE
ANOMALOUSLY DEEP CLOSED UPPER LOW WILL BE THE RESULT. WITH FURTHER
BLOCKING UPSTREAM OVER THE NORTH ATLANTIC...THIS WILL MOVE LITTLE
THUS SUSTAINING NORTHWEST FLOW OVER THE REGION WITH REGULAR
REINFORCING SHOTS OF REALLY COLD AIR BY MARCH STANDARDS.
TONIGHT...MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THE SHORT
WAVE OVER MO MOVING NORTHEAST AND BRINGING WITH IT THE ONGOING
WARM MOIST ADVECTION ALOFT THAT HAS PRODUCED PRECIP DOWNSTATE
TODAY. MODEL DIFFERENCES REMAIN IN PRECIP TYPE WHICH CAN BE
EXPECTED WITH HOW CLOSE TO 0C A GOOD PART OF THE FORECAST THERMAL
PROFILES ARE. VARIOUS WRF AND ARW MODELS INDICATE PRECIP SHOULD
SLOWLY SPREAD NORTHWARD THROUGH CENTRAL IL THIS EVE AND FORECAST
ISENTROPIC SURFACES AND ELEVATED MOISTURE CONVERGENCE FROM BOTH
THE RAP AND NAM AGREE WITH THIS DEPICTION. SOME FLURRIES/DRIZZLE
AHEAD OF THE MAIN PRECIP AREA ARE POSSIBLE AS THE ATMOSPHERE
SATURATES.
THERE ARE SEVERAL CULPRITS FOR THE PRECIP TYPE QUESTIONS. FOR
ONE...BECAUSE THE AREA IS GRAZED BY THE LEAD SHORT WAVE AND ITS
DEEPER SATURATION...THERE IS UNCERTAINTY ON WHETHER ICE CRYSTALS
ARE INTRODUCED. SECOND...THERE IS A SEVERAL THOUSAND FT DEEP
LAYER AROUND 0C FORECAST ACROSS A LARGE PART OF THE AREA AS PRECIP
SPREADS IN. AND FINALLY...SURFACE TEMPERATURES ARE LIKELY TO HOLD
STEADY THROUGH LATE EVE AND OVERNIGHT...AND MAY EVEN INCH UP IN
THE FAR SOUTH DEPENDING ON PRECIP STRENGTH...WHICH PRIMARILY LOOKS
LIGHT.
WHILE THERE MAY BE LIGHT SNOW IN THE ONSET SOUTH OF I-80 THIS EVE
AS THE WARM NOSE IS MARGINAL...IT APPEARS THAT BY OVERNIGHT THIS
LAYER WILL BE DEEP ENOUGH TO SUPPORT FULL MELTING. THE MOISTURE
TRANSPORT NOSE FROM THE SHORT WAVE POINTS INTO THE SOUTHEAST
FORECAST AREA...AND DO HAVE AROUND ONE TENTH OF AN INCH OF QPF.
SURFACE TEMPERATURES LOOK TO BE JUST ABOVE FREEZING THERE...BUT
WILL NEED TO BE WATCHED CLOSELY. FURTHER TO THE NORTH...TOWARD
I-80 AND EVEN SOMEWHAT NORTH FROM THERE...QPF LOOKS TO BE LIGHT
OVERNIGHT...BUT PROFILES DO SUPPORT LIGHT FREEZING RAIN OR SLEET
DEPENDING ON WHICH MODEL. THIS DOES INCLUDE FOR DOWNTOWN CHICAGO.
TOWARD FAR NORTHERN IL...THE PROFILES BECOME COOL ENOUGH THAT THE
TYPE SHOULD BE SLEET OR SNOW...BUT AGAIN PRIOR TO DAYBREAK THIS
LOOKS TO BE LIGHT.
AS THE MAIN UPPER WAVE APPROACHES MONDAY MORNING...GUIDANCE
AGREES ON THIS BEING THE STRONGEST PERIOD OF OMEGA/QG FORCING FOR
THE NORTHERN AREA. BECAUSE OF THIS FORCING AND THE ALREADY VERY
MARGINAL PROFILES FOR ANYTHING BUT SNOW THAT FAR NORTH...PRECIP
TYPE LOOKS TO TRANSITION TO A WET SNOW. THE HIGHER RATES SHOULD BE
TO THE NORTH OF THE CWA BUT ENOUGH SUPPORT WITH 31F-33F SURFACE
TEMPERATURES TO SUPPORT UP TO A COUPLE INCHES OF SNOW NEAR THE WI
BORDER. THE BEST TIMING FOR CHICAGO LOOKS TO BE FROM MID TO LATE
MORNING INTO EARLY AFTERNOON...WITH A DUSTING SOUTH TO ONE TO TWO
INCHES IN THE NORTH. STRONG DRYING IN THE MID-LEVELS IS FORECAST
TO FLOOD OVER THE AREA DURING THE AFTERNOON...CUTTING OFF MOST OF
THE FORCING FOR PRECIP. THIS WILL ALLOW TEMPERATURES TO MODERATE
ACROSS MUCH OF THE AREA BEFORE THE INCOMING PLUNGE...AND ITS
POSSIBLE MID 40S ARE REACHED SOUTH OF I-80 DEPENDING ON DEGREE OF
SCATTERING.
BY EARLY MONDAY EVE THE SYSTEMS COLD FRONT WILL BE SWEEPING ACROSS
NORTH CENTRAL IL. THE TEMPERATURE DROP LOOKS TO BE SHARP FOR THE
FIRST COUPLE HOURS AFTER THE FRONT AND HAVE TRIED TO MASSAGE SOME
OF THAT INTO THE HOURLY FORECAST GRIDS GIVEN THE HIGH CONFIDENCE
ALREADY. WITH THE MIXED BOUNDARY LAYER AND STRONG ISALLOBARIC
COMPONENT FORECAST...WINDS LOOK TO BE GUSTING TO 30 AND MAYBE EVEN
40 MPH /ESPECIALLY RIGHT AFTER FROPA/. THE CIPS ANALOG GUIDANCE
DOES HAVE A MAJORITY OF ITS MATCHES FAVORING GUSTS THAT HIGH IN
THE REGION. WIND CHILLS ARE EXPECTED TO FREE FALL INTO THE SINGLE
DIGITS BY MID EVE...AND THEN BELOW ZERO IN NORTHERN AREAS
OVERNIGHT. AS THE UPPER LOW MOVES ACROSS WI...ITS SOUTHERN FLANK
OF MID-LEVEL COLD AIR ADVECTION AND WRAPAROUND LOW-LEVEL MOISTURE
MAY BE ENOUGH TO SUPPORT FLURRIES OR EVEN SHOW SHOWERS. WHILE THIS
WILL BE LIGHT GIVEN LIMITED OVERALL FORCING...WITH THE GUSTY WINDS
AND THE LOWERING WATER CONTENT OF THE SNOW...THERE MAY BE SOME
MARKEDLY REDUCED VISIBILITIES IF AND WHERE SOME OF THIS SNOW
IS ABLE MATERIALIZE ACROSS FAR NORTHERN IL MONDAY EVE.
FOR TUESDAY AND BEYOND...THE COLD AIR ADVECTION CONTINUES TO
REINFORCE ITSELF WITH MULTIPLE COLD FRONTS AND MASSIVE CYCLONIC
FLOW. THIS FLOW WILL KEEP THE POTENTIAL FOR AT LEAST
STRATOCU...ALONG WITH THE CHANCE FOR SNOW SHOWERS.
HOWEVER...TEMPERATURES WERE THE FOCUS...AND THEY LOOK TO BE
REMARKABLY LOW FOR THE LATTER HALF OF MARCH. 850MB TEMPERATURES
ARE FORECAST TO DROP TO AROUND -15C TUE MORNING AND THEN AGAIN WED
MORNING. THE SURFACE WIND COMPONENT REMAINS ELEVATED THROUGH
WED...BUT STILL NIGHTTIME TEMPERATURES WILL FALL INTO THE TEENS
AREA WIDE THANKS TO THE COLD AIR ADVECTION. HIGHS WILL NOT REBOUND
MUCH...AND IN SOME PLACES WILL REMAIN BELOW 30F ON WEDNESDAY. IN
FACT...THE LOW MAXIMUM TEMPERATURE RECORD FOR WED IN ROCKFORD OF
ONLY 22F LOOKS TO BE POTENTIALLY IN JEOPARDY. THE SURFACE
HIGH BUILDS IN LATER THU THROUGH THE EARLY PART OF THE WEEKEND.
WITH THE BLOCKED FLOW...THE COLD AIR MASS HAS NO WHERE TO GO BUT
REINFORCE ITSELF FROM THE NORTH. AND ON THAT NOTE...BACKWARDS
TRAJECTORIES FROM THE GFS FOR WED INDICATE PARCELS ORIGINATING FROM
60 DEGREES NORTH LATITUDE /THE BORDER OF THE NORTHERN AND
SOUTHERN CANADIAN PROVINCES/. ALSO CONSIDERING THE EXTENT OF THE
SNOW COVER TO OUR NORTHWEST...WHICH WILL EXPAND TONIGHT INTO
MONDAY...LITTLE AIR MASS MODIFICATION IS ABLE TO OCCUR.
QUITE FASCINATING FOR LATE MARCH!
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* TIMING/TYPE OF PRECIPITATION LATE TONIGHT/MONDAY...MIXED PRECIP
LIKELY.
* MVFR/IFR CONDITIONS MONDAY.
* EAST WINDS OVERNIGHT...VEERING WEST-SOUTHWEST MIDDAY MONDAY AND
INCREASING TO 20-30 KT BY MONDAY EVENING.
RATZER
//DISCUSSION...UPDATED 00Z...
QUITE A BIT OF WEATHER GOING ON DURING THE 24-30 HOUR FORECAST
PERIOD.
HIGH PRESSURE OVER THE EASTERN GREAT LAKES REGION WILL DRIFT EAST
ACROSS NEW ENGLAND BY EARLY MONDAY MORNING...WHILE A PAIR OF LOW
PRESSURE SYSTEMS MOVE INTO THE UPPER MIDWEST AND LOWER OHIO VALLEY
REGIONS. COOL...DRY EAST SFC FLOW WILL REMAIN IN PLACE ACROSS THE
TERMINALS MUCH OF TONIGHT...WHILE WARM/MOIST AIR SPREADS IN ALOFT
AS AN UPPER LEVEL DISTURBANCE APPROACHES. THIS IS EXPECTED TO
LEAD TO SATURATION AND PRECIPITATION DEVELOPMENT FROM THE SOUTH-
SOUTHWEST BY SUNRISE MONDAY. FORECAST THERMAL PROFILES FROM
VARIOUS MODELS INDICATE TEMPERATURES NEAR/SLIGHTLY ABOVE FREEZING
IN THE LOWER 5000 FT OR SO OF THE ATMOSPHERE...PRESENTING THE
LIKELIHOOD OF MIXED PRECIP ACROSS THE TERMINALS MONDAY MORNING.
THESE PROFILES SUGGEST AREAS FARTHER NORTH/NORTHWEST SHOULD SEE
MORE OF A SNOW/PSBL SLEET MIX...TRENDING MORE TOWARD RAIN/FREEZING
RAIN/SLEET WITH SLIGHTLY WARMER TEMPS ALOFT FARTHER SOUTH FOR
KMDW AND KGYY TERMINALS. SURFACE TEMPERATURES SHOULD RISE ABOVE
FREEZING IN MOST AREAS BY LATE MORNING...WITH MID-LEVEL DRY AIR
ALSO ARRIVING AND RESULTING IN A DECREASE IN PRECIPITATION
INTENSITY AND A TREND MORE TOWARD DRIZZLE. IT APPEARS THAT IFR
CONDITIONS ARE FAIRLY LIKELY IF DEEP SATURATION/PRECIP INDICATED
BY MODEL FORECASTS DOES INDEED OCCUR...THUS THE MORNING THROUGH
MIDDAY HOURS LOOK TO BE THE MOST CHALLENGING WITH MIXED PRECIP AND
IFR CIG/VIS CONDITIONS. IFR CIGS/FOG MAY LINGER A FEW HOURS INTO
EARLY AFTERNOON...BEFORE IMPROVING QUICKLY DURING THE AFTERNOON.
THE MAIN SURFACE LOW WILL PASS WELL NORTH OF THE AREA DURING THE
DAY...WITH A SURFACE TROUGH EXTENDING SOUTHEAST THROUGH THE AREA
TO THE WEAKER SOUTHERN LOW. WINDS WILL START OUT BRISK EASTERLY...
BUT WILL DIMINISH AND VEER TO THE WEST-SOUTHWEST AS THE SURFACE
TROUGH AXIS MOVES ACROSS THE TERMINALS MIDDAY. WEST-SOUTHWEST
WINDS WILL THEN INCREASE SIGNIFICANTLY BY LATE AFTERNOON AND
EVENING...AS COLDER AIR BEGINS TO WRAP IN FROM THE WEST. THIS WILL
RESULT IN LOW LEVEL LAPSE RATES STEEPENING SHARPLY...WITH WINDS
INCREASING INTO THE 20-30 KT RANGE FROM THE WEST BY EVENING. THIS
WILL ALSO LIKELY RESULT IN AN MVFR STRATOCU LAYER DEVELOPING IN
THE 2000 FT AGL RANGE...WITH A PERIOD OF CONVECTIVE SNOW
SHOWERS/FLURRIES POSSIBLE DURING THE EVENING.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE IN WIND TRENDS.
* MEDIUM CONFIDENCE IN TIMING/TRENDS AND TYPE OF PRECIP.
* MEDIUM CONFIDENCE IN PERIOD OF PREVAILING IFR CIG/VIS DURING
MONDAY MORNING/MIDDAY.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY THROUGH SATURDAY...MAINLY VFR. GUSTY WEST WINDS TUE.
RATZER
&&
.MARINE...
233 PM CDT
MAIN CONCERN FOR THE MARINE FORECAST WILL BE PERIOD OF GALES
POSSIBLE MONDAY EVENING THROUGH LATE TUESDAY. TODAY...HIGH PRESSURE
IS CENTERED OVER THE GREAT LAKES REGION PROVIDING DIMINISHING
EAST/NORTHEAST FLOW ACROSS LAKE MICHIGAN. TWO AREAS OF LOW PRESSURE
ARE TAKING SHAPE...ONE ACROSS THE NORTHERN ROCKIES AND THE SECOND
OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THE NORTHERN LOW
IS EXPECTED TO MOVE EAST INTO MINNESOTA TONIGHT WITH WINDS OVER THE
LAKE BECOMING SOUTHEAST AND INCREASING INTO THE 20 TO 25 KT POSSIBLY
30 KT RANGE. THE GRADIENT AHEAD OF THE LOW THEN QUICKLY DIMINISHES
MONDAY AS THE LOW MOVES INTO WISCONSIN AND BROAD TROUGHING TAKES
PLACES ACROSS LAKE MICHIGAN BETWEEN THE NORTHERN LOW...AND THE
SOUTHERN LOW AS IT MOVES INTO THE SOUTHERN APPALACHIANS. THIS SHOULD
ALLOW WINDS TO DIMINISH FOR A SHORT PERIOD DURING THE DAY MONDAY
BEFORE WINDS TURN SOUTHWEST...THEN WEST AND QUICKLY INCREASE AGAIN
AS THE NORTHERN LOW MOVES EAST OF LAKE MICHIGAN. WITH THE GRADIENT
QUICKLY STRENGTHENS AND STRONG HEIGHT RISES MOVING IN BEHIND THE
DEPARTING LOW...GALES ARE EXPECTED ACROSS PORTIONS OF LAKE MICHIGAN.
CURRENTLY...THE BEST CHANCES FOR GALES APPEAR ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE LAKE...WITH THE GRADIENT SLIGHTLY WEAKER
ACROSS FAR NORTHERN LAKE MICHIGAN CLOSER TO THE LOW TRACK. WILL
ISSUE A GALE WATCH FOR THESE AREAS MONDAY EVENING THROUGH TUESDAY
EVENING. WINDS REMAIN ELEVATED AROUND 30 KT THROUGH THE DAY
WEDNESDAY BEFORE GRADUALLY TAPERING LATE IN THE WEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
GALE WATCH...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WATCH...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
245 PM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* MVFR CEILINGS IMPROVING GRAUDALLY THROUGH THE REST OF THE
AFTERNOON. POSSIBLY BECOMING SCATTERED CLOUDS THIS EVENING.
* NORTHERLY WINDS...OCCASIONALLY GUSTING TO NEAR 20 KT.
PAW
//DISCUSSION...UPDATED 18Z...
THE SYSTEM THAT WAS CENTERED IN INDIANA EARLY THIS MORNING HAS
MOVED INTO OHIO AND WILL CONTINUE MOVING TO THE EAST. HIGH
PRESSURE IS STARING TO BUILD INTO THE AREA...WHICH HAS ALLOWED
WINDS TO BECOME MORE NORTHERLY AND BRING IN SOME DRIER AIR AT LOW
LEVELS. CEILINGS AND VISIBILITIES HAVE IMPROVED WITH THE DRIER
AIR...AND THE IMPROVING TREND WILL CONTINUE THROUGH THE AFTERNOON
AND EVENING. THEN CEILINGS WILL SCATTER OUT OVERNIGHT AS THE HIGH
PRESSURE RIDGE GETS CLOSER.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN CEILING DETAILS.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE OF MIXED PRECIPITATION LATE...MVFR
POSSIBLE.
MONDAY...RAIN/SNOW LIKELY. IFR POSSIBLE.
TUESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
202 PM CDT
SMALL CRAFT CONDITIONS WILL CONTINUE THROUGH THIS EVENING FOR BOTH
THE ILLINOIS AND INDIANA SHORES AS THE WAVES WILL LIKELY REMAIN
ELEVATED FROM THE PERSISTENT ONSHORE FLOW UP AROUND 20 TO 25 KT.
WINDS WILL BE ON AN UPWARD TREND LATER TONIGHT FOR A PERIOD ACROSS
THE NORTH END OF THE LAKE AS ANOTHER SURFACE TROUGH/COLD FRONT
PUSHES ACROSS THE LAKE. WINDS WILL GRADUALLY BECOME NORTHERLY UP TO
25 TO 30 KT LATE TONIGHT. HOWEVER...THESE STRONGER WINDS WILL BE
SHORT LIVED AND WILL QUICKLY ABATE ON SUNDAY AS A SURFACE HIGH
BUILDS OVER THE NORTH END OF THE LAKE...LEADING TO LIGHT AND
VARIABLE WINDS BY LATE SUNDAY MORNING.
A STORM SYSTEM WILL MOVE FROM THE PLAINS EASTWARD ACROSS THE UPPER
MISSISSIPPI VALLEY BY MONDAY. THIS SYSTEM WILL RESULT IN A PERIOD OF
STOUT EAST-SOUTHEASTERLY WINDS UP TO 25 TO 30 KT OVER THE LAKE
SUNDAY NIGHT AND INTO MONDAY. THIS LOW IS EXPECTED TO DRIVE ANOTHER
DECENT COLD FRONT ACROSS THE LAKE BY LATE MONDAY AFTERNOON OR
EVENING. IN THE WAKE OF THIS FRONT IT APPEARS THE WINDS WILL TURN
OUT OF THE WEST AND INCREASE UP TO 35 TO 40 KT GALES MONDAY NIGHT
AND TUESDAY. GALES COULD EVEN AFFECT THE NEAR SHORES AS WELL IN
SPITE OF THE OFFSHORE COMPONENT. IT ALSO APPEARS THAT THERE COULD BE
SOME FREEZING SPRAY AS WELL OVER THE LAKE. THE COMBINATION OF THE
STRONG WINDS AND ABNORMAL COLD TEMPERATURES FOR LATE MARCH COULD
LEAD TO SOME MODERATE FREEZING SPRAY LATE MONDAY NIGHT INTO TUESDAY
MORNING.
ONCE THIS SURFACE LOW MOVES NORTHEASTWARD ACROSS SOUTHEASTERN
ONTARIO...A NEW STRONGER LOW WILL DEVELOP ACROSS THE NORTHEASTERN
SEABOARD...LEADING TO A WEAKENING TREND WITH THE SOUTHEASTERN
ONTARIO LOW. THIS NEW LOW LOOKS LIKE IT WILL REMAIN IN PLACE FOR AN
EXTENDED PERIOD ACROSS QUEBEC AS STRONG BLOCKING HIGH PRESSURE
REMAINS IN PLACE ACROSS THE NORTH ATLANTIC. OVERALL...THIS LOOKS TO
RESULT IN A PROLONGED PERIOD OF RATHER STOUT NORTHERLY FLOW UP AROUND
30 KT OVER THE LAKE THROUGH AT LEAST THE MIDDLE OF NEXT WEEK.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
203 PM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* SOME -DZ OR FLURRIES POSSIBLE UNTIL 19Z.
* MVFR CEILINGS IMPROVING GRADUALLY THROUGH THE AFTERNOON.
POSSIBLY BECOMING SCATTERED CLOUDS THIS EVENING.
* NORTHERLY WINDS...OCCASIONALLY GUSTING TO NEAR 20 KT.
PAW
//DISCUSSION...UPDATED 18Z...
THE SYSTEM THAT WAS CENTERED IN INDIANA EARLY THIS MORNING HAS
MOVED INTO OHIO AND WILL CONTINUE MOVING TO THE EAST. HIGH
PRESSURE IS STARING TO BUILD INTO THE AREA...WHICH HAS ALLOWED
WINDS TO BECOME MORE NORTHERLY AND BRING IN SOME DRIER AIR AT LOW
LEVELS. CEILINGS AND VISIBILITIES HAVE IMPROVED WITH THE DRIER
AIR...AND THE IMPROVING TREND WILL CONTINUE THROUGH THE AFTERNOON
AND EVENING. THEN CEILINGS WILL SCATTER OUT OVERNIGHT AS THE HIGH
PRESSURE RIDGE GETS CLOSER.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN TIMING OF PRECIPITATION ENDING.
* MEDIUM CONFIDENCE IN TIMING CEILING IMPROVEMENT.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE OF MIXED PRECIPITATION LATE...MVFR
POSSIBLE.
MONDAY...RAIN/SNOW LIKELY. IFR POSSIBLE.
TUESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
202 PM CDT
SMALL CRAFT CONDITIONS WILL CONTINUE THROUGH THIS EVENING FOR BOTH
THE ILLINOIS AND INDIANA SHORES AS THE WAVES WILL LIKELY REMAIN
ELEVATED FROM THE PERSISTENT ONSHORE FLOW UP AROUND 20 TO 25 KT.
WINDS WILL BE ON AN UPWARD TREND LATER TONIGHT FOR A PERIOD ACROSS
THE NORTH END OF THE LAKE AS ANOTHER SURFACE TROUGH/COLD FRONT
PUSHES ACROSS THE LAKE. WINDS WILL GRADUALLY BECOME NORTHERLY UP TO
25 TO 30 KT LATE TONIGHT. HOWEVER...THESE STRONGER WINDS WILL BE
SHORT LIVED AND WILL QUICKLY ABATE ON SUNDAY AS A SURFACE HIGH
BUILDS OVER THE NORTH END OF THE LAKE...LEADING TO LIGHT AND
VARIABLE WINDS BY LATE SUNDAY MORNING.
A STORM SYSTEM WILL MOVE FROM THE PLAINS EASTWARD ACROSS THE UPPER
MISSISSIPPI VALLEY BY MONDAY. THIS SYSTEM WILL RESULT IN A PERIOD OF
STOUT EAST-SOUTHEASTERLY WINDS UP TO 25 TO 30 KT OVER THE LAKE
SUNDAY NIGHT AND INTO MONDAY. THIS LOW IS EXPECTED TO DRIVE ANOTHER
DECENT COLD FRONT ACROSS THE LAKE BY LATE MONDAY AFTERNOON OR
EVENING. IN THE WAKE OF THIS FRONT IT APPEARS THE WINDS WILL TURN
OUT OF THE WEST AND INCREASE UP TO 35 TO 40 KT GALES MONDAY NIGHT
AND TUESDAY. GALES COULD EVEN AFFECT THE NEAR SHORES AS WELL IN
SPITE OF THE OFFSHORE COMPONENT. IT ALSO APPEARS THAT THERE COULD BE
SOME FREEZING SPRAY AS WELL OVER THE LAKE. THE COMBINATION OF THE
STRONG WINDS AND ABNORMAL COLD TEMPERATURES FOR LATE MARCH COULD
LEAD TO SOME MODERATE FREEZING SPRAY LATE MONDAY NIGHT INTO TUESDAY
MORNING.
ONCE THIS SURFACE LOW MOVES NORTHEASTWARD ACROSS SOUTHEASTERN
ONTARIO...A NEW STRONGER LOW WILL DEVELOP ACROSS THE NORTHEASTERN
SEABOARD...LEADING TO A WEAKENING TREND WITH THE SOUTHEASTERN
ONTARIO LOW. THIS NEW LOW LOOKS LIKE IT WILL REMAIN IN PLACE FOR AN
EXTENDED PERIOD ACROSS QUEBEC AS STRONG BLOCKING HIGH PRESSURE
REMAINS IN PLACE ACROSS THE NORTH ATLANTIC. OVERALL...THIS LOOKS TO
RESULT IN A PROLONGED PERIOD OF RATHER STOUT NORTHERLY FLOW UP AROUND
30 KT OVER THE LAKE THROUGH AT LEAST THE MIDDLE OF NEXT WEEK.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1245 PM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* SOME -DZ OR FLURRIES POSSIBLE UNTIL 19Z.
* MVFR CEILINGS IMPROVING GRADUALLY THROUGH THE AFTERNOON.
POSSIBLY BECOMING SCATTERED CLOUDS THIS EVENING.
* NORTHERLY WINDS...OCCASIONALLY GUSTING TO NEAR 20 KT.
PAW
//DISCUSSION...UPDATED 18Z...
THE SYSTEM THAT WAS CENTERED IN INDIANA EARLY THIS MORNING HAS
MOVED INTO OHIO AND WILL CONTINUE MOVING TO THE EAST. HIGH
PRESSURE IS STARING TO BUILD INTO THE AREA...WHICH HAS ALLOWED
WINDS TO BECOME MORE NORTHERLY AND BRING IN SOME DRIER AIR AT LOW
LEVELS. CEILINGS AND VISIBILITIES HAVE IMPROVED WITH THE DRIER
AIR...AND THE IMPROVING TREND WILL CONTINUE THROUGH THE AFTERNOON
AND EVENING. THEN CEILINGS WILL SCATTER OUT OVERNIGHT AS THE HIGH
PRESSURE RIDGE GETS CLOSER.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN TIMING OF PRECIPITATION ENDING.
* MEDIUM CONFIDENCE IN TIMING CEILING IMPROVEMENT.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE OF MIXED PRECIPITATION LATE...MVFR
POSSIBLE.
MONDAY...RAIN/SNOW LIKELY. IFR POSSIBLE.
TUESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
315 AM CDT
LOW PRESSURE CONTINUES TO MOVE EASTWARD ACROSS SOUTHERN ILLINOIS ON
ITS WAY TOWARD THE OHIO RIVER VALLEY AND INTO THE MID ATLANTIC
THROUGH TODAY. AN INVERTED TROUGH EXTENDS NORTH OF THE LOW UP THE
MID/UPPER MISSISSIPPI RIVER VALLEY WHILE HIGH PRESSURE RIDGING
EXTENDS FROM THE CANADIAN PRAIRIES INTO THE CENTRAL PLAINS. THIS
WILL ACT TO TURN WINDS FROM NORTHEAST TO NORTH THROUGH THE MORNING.
AT THE MOMENT...THE STRONGEST SPEEDS...AROUND 25 KT...ARE FOUND
ACROSS THE CENTRAL THIRD OF LAKE MICHIGAN AND THESE LOOK TO EASE
SLIGHTLY THROUGH THE MORNING BUT OVERALL EXPECT 15 TO 20 KT WINDS TO
PREVAIL FROM LATE MORNING THROUGH THE AFTERNOON ACROSS THE SOUTHERN
HALF OF THE LAKE. AS THIS OCCURS...WINDS WILL DIMINISH NORTH AS THE
PRESSURE GRADIENT SLACKENS WITH A SECONDARY RIDGE AXIS EXTENDING
EASTWARD ACROSS CENTRAL ONTARIO. THE MAIN CONCERN FOR TODAY WILL BE
SMALL CRAFT ADVISORY LEVEL WAVES ACROSS THE IL/IN NEARSHORE WATERS
GIVEN THE LENGTHENING FETCH OF WIND AND PERSISTENT SPEEDS. WILL
CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS...WITH WAVES SUBSIDING
THIS EVENING. THE MAIN HIGH PRESSURE AREA WILL SETTLE SOUTHWARD INTO
THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE A SURFACE LOW DROPS
SOUTHEASTWARD ACROSS CENTRAL/EASTERN ONTARIO. THIS WILL RESULT IN
THE PRESSURE GRADIENT INCREASING ACROSS THE LAKE ONCE AGAIN
SUPPORTING AN INCREASE IN WIND SPEEDS THIS EVENING AND
TONIGHT...WITH THE STRONGEST SPEEDS NORTH. THE STRONGER WINDS WILL
BE SHORT LIVED AS HIGH PRESSURE PASSES OVER THE LAKE SUNDAY
RESULTING IN MUCH LIGHTER WINDS WITH A SHIFT TO THE EAST AND
SOUTHEAST LATER IN THE DAY/EVENING AS THE HIGH SHIFTS EAST OF THE
LAKE. WAVES WILL BUILD AS THE WINDS COME UP LATER TONIGHT AND
NEARSHORE AREAS MAY FLIRT WITH SMALL CRAFT ADVISORY LEVEL WAVES FOR
A SHORT TIME LATE SUNDAY MORNING BUT THIS LOOKS MARGINAL RIGHT NOW.
LOW PRESSURE WILL BE TAKING SHAPE ACROSS THE WESTERN DAKOTAS
SUNDAY AND MOVE NORTHEASTWARD ACROSS NORTHERN MINNESOTA MONDAY AND
EVENTUALLY SOUTHERN LAKE SUPERIOR MONDAY NIGHT. THIS TRACK IS A BIT
FURTHER NORTH THAN EARLIER INDICATED. AS THE LOW APPROACHES...SOUTH
TO SOUTHEAST WINDS WILL INCREASE MONDAY THEN TURN SOUTHWEST THEN
NORTHWEST MONDAY NIGHT INTO TUESDAY MORNING. THE FURTHER NORTH TRACK
WOULD ALLOW STRONGER SPEEDS ACROSS MORE OF THE LAKE WITH A PERIOD OF
LOW TO POSSIBLY MID RANGE GALES POSSIBLE ACROSS THE ENTIRE LAKE
STARTING MONDAY NIGHT AND WINDING DOWN BY EARLY TUESDAY
AFTERNOON...THOUGH SPEEDS WILL BE SLOW TO FALL BELOW 30 KT INTO
TUESDAY EVENING. THE LOW WILL SLOW AS IT MOVES INTO QUEBEC EARLY
WEDNESDAY WHILE HIGH PRESSURE SPREADS INTO THE UPPER MIDWEST WHICH
WILL LEAD TO A PERSISTENT NORTHWEST BREEZE THROUGH WEDNESDAY. WINDS
WILL THEN DIMINISH LATER WEDNESDAY AS THE HIGH MOVES OVER THE LAKE
THURSDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1105 AM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* MVFR/IFR CEILINGS WILL GRADUALLY IMPROVE THROUGH THE AFTERNOON.
POSSIBLY BECOMING SCATTERED CLOUDS THIS EVENING.
* PATCHY -DZ IN THE AREA ENDING AROUND 18Z.
* NORTHERLY WINDS. OCCASIONAL GUSTS TO NEAR 20 KT UNTIL 18Z.
PAW
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE ACROSS CENTRAL INDIANA CONTINUES TO MOVE EAST WITH AN
INVERTED TROUGH AXIS EXTENDING NORTHWARD FROM IT TOWARDS LAKE
MICHIGAN. LOW LEVEL MOISTURE REMAINS ABUNDANT WITH MAINLY IFR CIGS
AND VARIABLE IFR/MVFR VSBY ACROSS THE TERMINALS THIS MORNING.
DEEPER MOISTURE HAS EXITED TO THE SOUTHEAST WITH THE PASSAGE OF AN
UPPER WAVE BUT ENOUGH LIFT REMAINS TO FORCE DEVELOPMENT OF AREAS
OF DRIZZLE AND EVEN FREEZING DRIZZLE WHERE TEMPS ARE AT/BELOW
FREEZING. THE -DZ/-FZDZ WILL WIND DOWN THROUGH MID MORNING WHILE
CEILINGS GRADUALLY IMPROVE AS DRIER LOW LEVEL AIR TRIES TO WORK IN
FROM THE NORTH/NORTHEAST. BIGGEST CHALLENGE BECOMES TIMING CIG
IMPROVEMENTS TO MVFR AND POSSIBLY EVEN LOW END VFR IF ENOUGH DRY
AIR WORKS IN OR BREAKS END UP DEVELOPING LATER IN THE DAY. MAY BE
A BIT ON THE CONSERVATIVE SIDE WITH THE SPEED OF
IMPROVEMENT BUT MANY SITES UPSTREAM HAVE LOWERED TO IFR SO HOLDING
ONTO IT THROUGH THE MORNING SEEMS TO MAKE THE MOST SENSE. THE NEXT
QUESTION BECOMES HOW MUCH CLOUD COVER WILL BE IN PLACE THROUGH
TONIGHT. WILL CONTINUE THE TREND OF THE PREVIOUS FORECASTS WITH
SCATTERED CLOUDS BUT ENOUGH MOISTURE MAY LINGER TO KEEP BKN
COVERAGE...ESPECIALLY IF CLOUD COVER REMAINS BKN-OVC THROUGH
SUNSET. OTHERWISE...WINDS WILL TURN NORTHWESTERLY THIS EVENING
THEN RETURN TO NORTH AND EVENTUALLY NORTHEAST OR EAST-NORTHEAST
BY MID SUNDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE IN TIMING OF CEILING IMPROVEMENT.
* MEDIUM CONFIDENCE IN TIMING OF -DZ ENDING.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE OF MIXED PRECIPITATION LATE...MVFR
POSSIBLE.
MONDAY...RAIN/SNOW LIKELY. IFR POSSIBLE.
TUESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
315 AM CDT
LOW PRESSURE CONTINUES TO MOVE EASTWARD ACROSS SOUTHERN ILLINOIS ON
ITS WAY TOWARD THE OHIO RIVER VALLEY AND INTO THE MID ATLANTIC
THROUGH TODAY. AN INVERTED TROUGH EXTENDS NORTH OF THE LOW UP THE
MID/UPPER MISSISSIPPI RIVER VALLEY WHILE HIGH PRESSURE RIDGING
EXTENDS FROM THE CANADIAN PRAIRIES INTO THE CENTRAL PLAINS. THIS
WILL ACT TO TURN WINDS FROM NORTHEAST TO NORTH THROUGH THE MORNING.
AT THE MOMENT...THE STRONGEST SPEEDS...AROUND 25 KT...ARE FOUND
ACROSS THE CENTRAL THIRD OF LAKE MICHIGAN AND THESE LOOK TO EASE
SLIGHTLY THROUGH THE MORNING BUT OVERALL EXPECT 15 TO 20 KT WINDS TO
PREVAIL FROM LATE MORNING THROUGH THE AFTERNOON ACROSS THE SOUTHERN
HALF OF THE LAKE. AS THIS OCCURS...WINDS WILL DIMINISH NORTH AS THE
PRESSURE GRADIENT SLACKENS WITH A SECONDARY RIDGE AXIS EXTENDING
EASTWARD ACROSS CENTRAL ONTARIO. THE MAIN CONCERN FOR TODAY WILL BE
SMALL CRAFT ADVISORY LEVEL WAVES ACROSS THE IL/IN NEARSHORE WATERS
GIVEN THE LENGTHENING FETCH OF WIND AND PERSISTENT SPEEDS. WILL
CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS...WITH WAVES SUBSIDING
THIS EVENING. THE MAIN HIGH PRESSURE AREA WILL SETTLE SOUTHWARD INTO
THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE A SURFACE LOW DROPS
SOUTHEASTWARD ACROSS CENTRAL/EASTERN ONTARIO. THIS WILL RESULT IN
THE PRESSURE GRADIENT INCREASING ACROSS THE LAKE ONCE AGAIN
SUPPORTING AN INCREASE IN WIND SPEEDS THIS EVENING AND
TONIGHT...WITH THE STRONGEST SPEEDS NORTH. THE STRONGER WINDS WILL
BE SHORT LIVED AS HIGH PRESSURE PASSES OVER THE LAKE SUNDAY
RESULTING IN MUCH LIGHTER WINDS WITH A SHIFT TO THE EAST AND
SOUTHEAST LATER IN THE DAY/EVENING AS THE HIGH SHIFTS EAST OF THE
LAKE. WAVES WILL BUILD AS THE WINDS COME UP LATER TONIGHT AND
NEARSHORE AREAS MAY FLIRT WITH SMALL CRAFT ADVISORY LEVEL WAVES FOR
A SHORT TIME LATE SUNDAY MORNING BUT THIS LOOKS MARGINAL RIGHT NOW.
LOW PRESSURE WILL BE TAKING SHAPE ACROSS THE WESTERN DAKOTAS
SUNDAY AND MOVE NORTHEASTWARD ACROSS NORTHERN MINNESOTA MONDAY AND
EVENTUALLY SOUTHERN LAKE SUPERIOR MONDAY NIGHT. THIS TRACK IS A BIT
FURTHER NORTH THAN EARLIER INDICATED. AS THE LOW APPROACHES...SOUTH
TO SOUTHEAST WINDS WILL INCREASE MONDAY THEN TURN SOUTHWEST THEN
NORTHWEST MONDAY NIGHT INTO TUESDAY MORNING. THE FURTHER NORTH TRACK
WOULD ALLOW STRONGER SPEEDS ACROSS MORE OF THE LAKE WITH A PERIOD OF
LOW TO POSSIBLY MID RANGE GALES POSSIBLE ACROSS THE ENTIRE LAKE
STARTING MONDAY NIGHT AND WINDING DOWN BY EARLY TUESDAY
AFTERNOON...THOUGH SPEEDS WILL BE SLOW TO FALL BELOW 30 KT INTO
TUESDAY EVENING. THE LOW WILL SLOW AS IT MOVES INTO QUEBEC EARLY
WEDNESDAY WHILE HIGH PRESSURE SPREADS INTO THE UPPER MIDWEST WHICH
WILL LEAD TO A PERSISTENT NORTHWEST BREEZE THROUGH WEDNESDAY. WINDS
WILL THEN DIMINISH LATER WEDNESDAY AS THE HIGH MOVES OVER THE LAKE
THURSDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1005 AM CDT SAT MAR 16 2013
.DISCUSSION...
ISSUED 1005 AM CDT SAT MAR 16 2013
COLD FRONT HAS PASSED THROUGH THE CWA...AND AREAS SOUTH OF I-70
HAVE BEEN SEEING A SHARP TEMPERATURE FALL RECENTLY. A BAND OF
DENSE FOG HAS BEEN DROPPING SOUTHWARD IN THE WAKE OF THE FRONT
DESPITE WINDS GUSTING FROM 20 TO 30 MPH. 10 AM OBSERVATIONS WERE
SHOWING THIS DENSE FOG JUST NORTH OF I-70...ALTHOUGH COVERAGE HAS
BEEN BREAKING UP SOMEWHAT RECENTLY. SHOULD SEE THIS FOG CONTINUE
TO ERODE OVER THE NEXT COUPLE HOURS...ALTHOUGH CONDITIONS WILL
REMAIN RATHER HAZY INTO THE AFTERNOON.
HAVE SENT SOME ZONE/GRID UPDATES RECENTLY TO UPDATE THE
TEMPERATURES. SOME SLOW RECOVERY IN TEMPERATURES POSSIBLE IN THE
NORTHERN HALF OF THE CWA...BUT HAVE LOWERED HIGHS BY A FEW DEGREES
AS CLOUD COVER WILL REMAIN FAIRLY EXTENSIVE. TEMPERATURES IN THE
SOUTHEAST SHOULD BE STEADY OR FALL THROUGH THE AFTERNOON.
GEELHART
&&
.AVIATION...
ISSUED 654 AM CDT SAT MAR 16 2013...FOR THE 12Z TAFS
THE MAIN ISSUE WILL BE A BAND OF VLIFR/LIFR FOG AND CIGS
AFFECTING ALL TAF SITES THROUGH 14Z OR SO. VIS WILL IMPROVE TO
MVFR AND CIGS TO IFR BETWEEN 16Z AND 18Z BASED ON FORECAST
SOUNDINGS AND HRRR CIG/VIS OUTPUT. MVFR CONDITIONS SHOULD START
OUT THE AFTERNOON...BUT MIXING OF DRY AIR ALOFT SHOULD CAUSE SOME
BREAKS IN THE LOW CLOUDS TO DEVELOP AT LEAST ACROSS THE NORTHERN
TERMINALS OF PIA/BMI...PRODUCING VFR CONDITIONS BY LATE AFTERNOON.
THOSE VFR CONDITIONS SHOULD CONTINUE FOR ALL TAFS THE REST OF THE
NIGHT AS THE COLD FRONT AND RAIN/SNOW SHOWERS LIFT NORTH TOWARD
I-70 BUT REMAIN SOUTH OF THE TAF SITES.
AS FOR WIND CONDITIONS...THE COLD FRONT HAS DROPPED SOUTH OF ALL
TAF SITES ALREADY THIS MORNING...SETTING UP A NORTH-NORTHEAST WIND
ACROSS THE BOARD. WIND SPEEDS SHOULD REMAIN IN THE 10-15KT RANGE
THROUGH THE MORNING AS THE PRESSURE GRADIENT TIGHTENS BEHIND THE
DEPARTING LOW TO THE EAST AND COLD FRONT TO THE SOUTH. WINDS
SHOULD DIP BELOW 10KT THIS EVENING AS THE DIRECTION SHIFTS TO
PRIMARILY NORTHEAST.
SHIMON
&&
.PREV DISCUSSION...
ISSUED 236 AM CDT SAT MAR 16 2013
SHORT TERM...TODAY THROUGH MONDAY
07Z/2AM SURFACE ANALYSIS SHOWS STRONG FRONTAL BOUNDARY EXTENDING
FROM NORTHERN MISSOURI E/SE INTO THE OHIO RIVER VALLEY. A SHARP
TEMP CONTRAST IS EVIDENT ACROSS THE BOUNDARY...WITH READINGS
RANGING FROM THE MIDDLE 30S ACROSS THE FAR NORTHERN KILX CWA
AROUND GALESBURG AND LACON...TO THE LOWER 60S SOUTH OF I-70. A
WAVE OF LOW PRESSURE CURRENTLY OVER WEST-CENTRAL ILLINOIS WILL
TRACK ALONG THE FRONT THIS MORNING...EVENTUALLY GIVING IT A PUSH
SOUTHWARD. ONCE WINDS BECOME N/NE BEHIND THE DEPARTING WAVE...LOW
CLOUDS AND FOG CURRENTLY ACROSS IOWA AND NORTHERN ILLINOIS WILL
FILTER SOUTHWARD INTO THE AREA. END RESULT WILL BE AN OVERCAST AND
CHILLY DAY...WITH HIGHS MAINLY IN THE LOWER TO MIDDLE 40S. THE
EXCEPTION WILL BE SOUTH OF I-70...WHERE HIGH TEMPS IN THE MIDDLE
50S WILL BE ACHIEVED THIS MORNING...WITH READINGS DROPPING INTO
THE 40S AFTER FROPA.
FRONT IS STILL EXPECTED TO STALL TO THE SOUTH OF ILLINOIS...WITH
SEVERAL WAVES OF LOW PRESSURE PROVIDING CLOUDS AND LIGHT PRECIP TO
PARTS OF THE AREA TONIGHT THROUGH MONDAY. MAIN CHANGE FROM GOING
FORECAST IS THAT THE BOUNDARY SHOULD DROP A LITTLE FURTHER SOUTH
THAN PREVIOUSLY ANTICIPATED. 1032MB CANADIAN HIGH PRESSURE WILL
BUILD INTO THE GREAT LAKES...PUSHING THE FRONT INTO THE TENNESSEE
RIVER VALLEY. WITH VERY COLD/DRY AIR MASS FILTERING SOUTHWARD...THINK
THERE WILL BE A SHARP CUT-OFF TO THE NORTHERN EDGE OF THE PRECIP
SHIELD. AS SUCH...HAVE TRIMMED POPS BACK CONSIDERABLY...ESPECIALLY
FOR TONIGHT INTO SUNDAY. NAM KEEPS THE ENTIRE KILX CWA DRY UNTIL
SUNDAY AFTERNOON...WHEN A WAVE OF LIGHT PRECIP LIFTS NORTHWARD
TOWARD THE I-70 CORRIDOR. GFS IS A BIT MORE ROBUST WITH DRIVING
THE PRECIP NORTHWARD INTO THE COLD AIR MASS...HOWEVER EVEN IT HAS
BACKED OFF FROM ITS PREVIOUS SOLUTIONS. GIVEN MAGNITUDE OF
COLD/DRY AIR MASS TO THE NORTH...THINK NAM PROBABLY HAS THE BEST
HANDLE ON THE SITUATION...BUT WILL GO WITH A NAM/GFS BLEND FOR
THIS FORECAST PACKAGE. AS A RESULT...WILL INTRODUCE CHANCE POPS
ALONG/SOUTH OF I-70 TONIGHT...THEN WILL SPREAD CHANCES FURTHER
NORTH TO NEAR THE I-72 CORRIDOR ON SUNDAY. THERMAL PROFILES
SUPPORT A RAIN/SNOW MIX LATE TONIGHT INTO EARLY SUNDAY
MORNING...WITH JUST RAIN SUNDAY AFTERNOON. MODEL CONSENSUS THEN
LIFTS BOUNDARY FURTHER NORTHWARD SUNDAY NIGHT AS A NORTHERN STREAM
WAVE APPROACHES FROM THE NORTHWEST. WILL CARRY POPS ACROSS THE
BOARD...WITH THE BEST CHANCES STILL CONFINED TO THE FAR E/SE CWA.
ONCE AGAIN THERMAL PROFILES SUGGEST THE POTENTIAL FOR A RAIN/SNOW
MIX...HOWEVER WITH BORDERLINE AIR TEMPS AND ABOVE FREEZING GROUND
TEMPS...AM NOT EXPECTING ANY SNOW ACCUMULATION.
LONG TERM...TUESDAY THROUGH FRIDAY
ONCE NORTHERN STREAM WAVE CLEARS THE AREA ON MONDAY...QUIET
WEATHER WILL PREVAIL THROUGH THE EXTENDED. WITH UPPER LOW
EXPECTED TO REMAIN IN PLACE OVER EASTERN CANADA INTO NEW
ENGLAND...A COOL NORTHWESTERLY FLOW WILL ENSURE BELOW NORMAL TEMPS
THROUGH THE PERIOD. 00Z MAR 16 MODELS STILL IN DISAGREEMENT
CONCERNING NEXT POTENTIAL CHANCE FOR PRECIP LATE IN THE
WEEK. GFS BRINGS A WAVE AND ITS ASSOCIATED PRECIP ACROSS CENTRAL
ILLINOIS ON THURSDAY...WHILE THE ECMWF KEEPS THE WAVE SUPPRESSED
MUCH FURTHER SOUTH. GIVEN PREVAILING UPPER TROUGH IN PLACE TO THE
NORTH...THINK ECMWF IS THE WAY TO GO. AS A RESULT...WILL MAINTAIN
A COOL/DRY FORECAST THROUGH FRIDAY.
BARNES
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
906 AM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* IFR CEILINGS IMPROVING TO MVFR LATE MORNING/EARLY AFTERNOON.
POSSIBLY BECOMING SCATTERED CLOUDS THIS EVENING.
* OCCASIONAL MVFR VISIBILITY BECOMING VFR BY MIDDAY.
* -DZ ENDING BY LATE MORNING. SOME -FZDZ POSSIBLE WITH TEMPS RIGHT
AROUND FREEZING.
* NORTH TO NORTHEAST WINDS...GUSTING TO AROUND 20 KT THIS MORNING.
PAW
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE ACROSS CENTRAL INDIANA CONTINUES TO MOVE EAST WITH AN
INVERTED TROUGH AXIS EXTENDING NORTHWARD FROM IT TOWARDS LAKE
MICHIGAN. LOW LEVEL MOISTURE REMAINS ABUNDANT WITH MAINLY IFR CIGS
AND VARIABLE IFR/MVFR VSBY ACROSS THE TERMINALS THIS MORNING.
DEEPER MOISTURE HAS EXITED TO THE SOUTHEAST WITH THE PASSAGE OF AN
UPPER WAVE BUT ENOUGH LIFT REMAINS TO FORCE DEVELOPMENT OF AREAS
OF DRIZZLE AND EVEN FREEZING DRIZZLE WHERE TEMPS ARE AT/BELOW
FREEZING. THE -DZ/-FZDZ WILL WIND DOWN THROUGH MID MORNING WHILE
CEILINGS GRADUALLY IMPROVE AS DRIER LOW LEVEL AIR TRIES TO WORK IN
FROM THE NORTH/NORTHEAST. BIGGEST CHALLENGE BECOMES TIMING CIG
IMPROVEMENTS TO MVFR AND POSSIBLY EVEN LOW END VFR IF ENOUGH DRY
AIR WORKS IN OR BREAKS END UP DEVELOPING LATER IN THE DAY. MAY BE
A BIT ON THE CONSERVATIVE SIDE WITH THE SPEED OF
IMPROVEMENT BUT MANY SITES UPSTREAM HAVE LOWERED TO IFR SO HOLDING
ONTO IT THROUGH THE MORNING SEEMS TO MAKE THE MOST SENSE. THE NEXT
QUESTION BECOMES HOW MUCH CLOUD COVER WILL BE IN PLACE THROUGH
TONIGHT. WILL CONTINUE THE TREND OF THE PREVIOUS FORECASTS WITH
SCATTERED CLOUDS BUT ENOUGH MOISTURE MAY LINGER TO KEEP BKN
COVERAGE...ESPECIALLY IF CLOUD COVER REMAINS BKN-OVC THROUGH
SUNSET. OTHERWISE...WINDS WILL TURN NORTHWESTERLY THIS EVENING
THEN RETURN TO NORTH AND EVENTUALLY NORTHEAST OR EAST-NORTHEAST
BY MID SUNDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN TIMING OF CEILING AND VISIBILITY
IMPROVEMENT.
* MEDIUM CONFIDENCE IN TIMING OF -DZ/-FZDZ ENDING.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE OF MIXED PRECIPITATION LATE...MVFR
POSSIBLE.
MONDAY...RAIN/SNOW LIKELY. IFR POSSIBLE.
TUESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
315 AM CDT
LOW PRESSURE CONTINUES TO MOVE EASTWARD ACROSS SOUTHERN ILLINOIS ON
ITS WAY TOWARD THE OHIO RIVER VALLEY AND INTO THE MID ATLANTIC
THROUGH TODAY. AN INVERTED TROUGH EXTENDS NORTH OF THE LOW UP THE
MID/UPPER MISSISSIPPI RIVER VALLEY WHILE HIGH PRESSURE RIDGING
EXTENDS FROM THE CANADIAN PRAIRIES INTO THE CENTRAL PLAINS. THIS
WILL ACT TO TURN WINDS FROM NORTHEAST TO NORTH THROUGH THE MORNING.
AT THE MOMENT...THE STRONGEST SPEEDS...AROUND 25 KT...ARE FOUND
ACROSS THE CENTRAL THIRD OF LAKE MICHIGAN AND THESE LOOK TO EASE
SLIGHTLY THROUGH THE MORNING BUT OVERALL EXPECT 15 TO 20 KT WINDS TO
PREVAIL FROM LATE MORNING THROUGH THE AFTERNOON ACROSS THE SOUTHERN
HALF OF THE LAKE. AS THIS OCCURS...WINDS WILL DIMINISH NORTH AS THE
PRESSURE GRADIENT SLACKENS WITH A SECONDARY RIDGE AXIS EXTENDING
EASTWARD ACROSS CENTRAL ONTARIO. THE MAIN CONCERN FOR TODAY WILL BE
SMALL CRAFT ADVISORY LEVEL WAVES ACROSS THE IL/IN NEARSHORE WATERS
GIVEN THE LENGTHENING FETCH OF WIND AND PERSISTENT SPEEDS. WILL
CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS...WITH WAVES SUBSIDING
THIS EVENING. THE MAIN HIGH PRESSURE AREA WILL SETTLE SOUTHWARD INTO
THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE A SURFACE LOW DROPS
SOUTHEASTWARD ACROSS CENTRAL/EASTERN ONTARIO. THIS WILL RESULT IN
THE PRESSURE GRADIENT INCREASING ACROSS THE LAKE ONCE AGAIN
SUPPORTING AN INCREASE IN WIND SPEEDS THIS EVENING AND
TONIGHT...WITH THE STRONGEST SPEEDS NORTH. THE STRONGER WINDS WILL
BE SHORT LIVED AS HIGH PRESSURE PASSES OVER THE LAKE SUNDAY
RESULTING IN MUCH LIGHTER WINDS WITH A SHIFT TO THE EAST AND
SOUTHEAST LATER IN THE DAY/EVENING AS THE HIGH SHIFTS EAST OF THE
LAKE. WAVES WILL BUILD AS THE WINDS COME UP LATER TONIGHT AND
NEARSHORE AREAS MAY FLIRT WITH SMALL CRAFT ADVISORY LEVEL WAVES FOR
A SHORT TIME LATE SUNDAY MORNING BUT THIS LOOKS MARGINAL RIGHT NOW.
LOW PRESSURE WILL BE TAKING SHAPE ACROSS THE WESTERN DAKOTAS
SUNDAY AND MOVE NORTHEASTWARD ACROSS NORTHERN MINNESOTA MONDAY AND
EVENTUALLY SOUTHERN LAKE SUPERIOR MONDAY NIGHT. THIS TRACK IS A BIT
FURTHER NORTH THAN EARLIER INDICATED. AS THE LOW APPROACHES...SOUTH
TO SOUTHEAST WINDS WILL INCREASE MONDAY THEN TURN SOUTHWEST THEN
NORTHWEST MONDAY NIGHT INTO TUESDAY MORNING. THE FURTHER NORTH TRACK
WOULD ALLOW STRONGER SPEEDS ACROSS MORE OF THE LAKE WITH A PERIOD OF
LOW TO POSSIBLY MID RANGE GALES POSSIBLE ACROSS THE ENTIRE LAKE
STARTING MONDAY NIGHT AND WINDING DOWN BY EARLY TUESDAY
AFTERNOON...THOUGH SPEEDS WILL BE SLOW TO FALL BELOW 30 KT INTO
TUESDAY EVENING. THE LOW WILL SLOW AS IT MOVES INTO QUEBEC EARLY
WEDNESDAY WHILE HIGH PRESSURE SPREADS INTO THE UPPER MIDWEST WHICH
WILL LEAD TO A PERSISTENT NORTHWEST BREEZE THROUGH WEDNESDAY. WINDS
WILL THEN DIMINISH LATER WEDNESDAY AS THE HIGH MOVES OVER THE LAKE
THURSDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
654 AM CDT SAT MAR 16 2013
.DISCUSSION...
ISSUED 236 AM CDT SAT MAR 16 2013
SHORT TERM...TODAY THROUGH MONDAY
07Z/2AM SURFACE ANALYSIS SHOWS STRONG FRONTAL BOUNDARY EXTENDING
FROM NORTHERN MISSOURI E/SE INTO THE OHIO RIVER VALLEY. A SHARP
TEMP CONTRAST IS EVIDENT ACROSS THE BOUNDARY...WITH READINGS
RANGING FROM THE MIDDLE 30S ACROSS THE FAR NORTHERN KILX CWA
AROUND GALESBURG AND LACON...TO THE LOWER 60S SOUTH OF I-70. A
WAVE OF LOW PRESSURE CURRENTLY OVER WEST-CENTRAL ILLINOIS WILL
TRACK ALONG THE FRONT THIS MORNING...EVENTUALLY GIVING IT A PUSH
SOUTHWARD. ONCE WINDS BECOME N/NE BEHIND THE DEPARTING WAVE...LOW
CLOUDS AND FOG CURRENTLY ACROSS IOWA AND NORTHERN ILLINOIS WILL
FILTER SOUTHWARD INTO THE AREA. END RESULT WILL BE AN OVERCAST AND
CHILLY DAY...WITH HIGHS MAINLY IN THE LOWER TO MIDDLE 40S. THE
EXCEPTION WILL BE SOUTH OF I-70...WHERE HIGH TEMPS IN THE MIDDLE
50S WILL BE ACHIEVED THIS MORNING...WITH READINGS DROPPING INTO
THE 40S AFTER FROPA.
FRONT IS STILL EXPECTED TO STALL TO THE SOUTH OF ILLINOIS...WITH
SEVERAL WAVES OF LOW PRESSURE PROVIDING CLOUDS AND LIGHT PRECIP TO
PARTS OF THE AREA TONIGHT THROUGH MONDAY. MAIN CHANGE FROM GOING
FORECAST IS THAT THE BOUNDARY SHOULD DROP A LITTLE FURTHER SOUTH
THAN PREVIOUSLY ANTICIPATED. 1032MB CANADIAN HIGH PRESSURE WILL
BUILD INTO THE GREAT LAKES...PUSHING THE FRONT INTO THE TENNESSEE
RIVER VALLEY. WITH VERY COLD/DRY AIRMASS FILTERING SOUTHWARD...THINK
THERE WILL BE A SHARP CUT-OFF TO THE NORTHERN EDGE OF THE PRECIP
SHIELD. AS SUCH...HAVE TRIMMED POPS BACK CONSIDERABLY...ESPECIALLY
FOR TONIGHT INTO SUNDAY. NAM KEEPS THE ENTIRE KILX CWA DRY UNTIL
SUNDAY AFTERNOON...WHEN A WAVE OF LIGHT PRECIP LIFTS NORTHWARD
TOWARD THE I-70 CORRIDOR. GFS IS A BIT MORE ROBUST WITH DRIVING
THE PRECIP NORTHWARD INTO THE COLD AIRMASS...HOWEVER EVEN IT HAS
BACKED OFF FROM ITS PREVIOUS SOLUTIONS. GIVEN MAGNITUDE OF
COLD/DRY AIRMASS TO THE NORTH...THINK NAM PROBABLY HAS THE BEST
HANDLE ON THE SITUATION...BUT WILL GO WITH A NAM/GFS BLEND FOR
THIS FORECAST PACKAGE. AS A RESULT...WILL INTRODUCE CHANCE POPS
ALONG/SOUTH OF I-70 TONIGHT...THEN WILL SPREAD CHANCES FURTHER
NORTH TO NEAR THE I-72 CORRIDOR ON SUNDAY. THERMAL PROFILES
SUPPORT A RAIN/SNOW MIX LATE TONIGHT INTO EARLY SUNDAY
MORNING...WITH JUST RAIN SUNDAY AFTERNOON. MODEL CONSENSUS THEN
LIFTS BOUNDARY FURTHER NORTHWARD SUNDAY NIGHT AS A NORTHERN STREAM
WAVE APPROACHES FROM THE NORTHWEST. WILL CARRY POPS ACROSS THE
BOARD...WITH THE BEST CHANCES STILL CONFINED TO THE FAR E/SE CWA.
ONCE AGAIN THERMAL PROFILES SUGGEST THE POTENTIAL FOR A RAIN/SNOW
MIX...HOWEVER WITH BORDERLINE AIR TEMPS AND ABOVE FREEZING GROUND
TEMPS...AM NOT EXPECTING ANY SNOW ACCUMULATION.
LONG TERM...TUESDAY THROUGH FRIDAY
ONCE NORTHERN STREAM WAVE CLEARS THE AREA ON MONDAY...QUIET
WEATHER WILL PREVAIL THROUGH THE EXTENDED. WITH UPPER LOW
EXPECTED TO REMAIN IN PLACE OVER EASTERN CANADA INTO NEW
ENGLAND...A COOL NORTHWESTERLY FLOW WILL ENSURE BELOW NORMAL TEMPS
THROUGH THE PERIOD. 00Z MAR 16 MODELS STILL IN DISAGREEMENT
CONCERNING NEXT POTENTIAL CHANCE FOR PRECIP LATE IN THE
WEEK. GFS BRINGS A WAVE AND ITS ASSOCIATED PRECIP ACROSS CENTRAL
ILLINOIS ON THURSDAY...WHILE THE ECMWF KEEPS THE WAVE SUPPRESSED
MUCH FURTHER SOUTH. GIVEN PREVAILING UPPER TROUGH IN PLACE TO THE
NORTH...THINK ECMWF IS THE WAY TO GO. AS A RESULT...WILL MAINTAIN
A COOL/DRY FORECAST THROUGH FRIDAY.
BARNES
&&
.AVIATION...
ISSUED 654 AM CDT SAT MAR 16 2013...FOR THE 12Z TAFS
THE MAIN ISSUE WILL BE A BAND OF VLIFR/LIFR FOG AND CIGS
AFFECTING ALL TAF SITES THROUGH 14Z OR SO. VIS WILL IMPROVE TO
MVFR AND CIGS TO IFR BETWEEN 16Z AND 18Z BASED ON FORECAST
SOUNDINGS AND HRRR CIG/VIS OUTPUT. MVFR CONDITIONS SHOULD START
OUT THE AFTERNOON...BUT MIXING OF DRY AIR ALOFT SHOULD CAUSE SOME
BREAKS IN THE LOW CLOUDS TO DEVELOP AT LEAST ACROSS THE NORTHERN
TERMINALS OF PIA/BMI...PRODUCING VFR CONDITIONS BY LATE AFTERNOON.
THOSE VFR CONDITIONS SHOULD CONTINUE FOR ALL TAFS THE REST OF THE
NIGHT AS THE COLD FRONT AND RAIN/SNOW SHOWERS LIFT NORTH TOWARD
I-70 BUT REMAIN SOUTH OF THE TAF SITES.
AS FOR WIND CONDITIONS...THE COLD FRONT HAS DROPPED SOUTH OF ALL
TAF SITES ALREADY THIS MORNING...SETTING UP A NORTH-NORTHEAST WIND
ACROSS THE BOARD. WIND SPEEDS SHOULD REMAIN IN THE 10-15KT RANGE
THROUGH THE MORNING AS THE PRESSURE GRADIENT TIGHTENS BEHIND THE
DEPARTING LOW TO THE EAST AND COLD FRONT TO THE SOUTH. WINDS
SHOULD DIP BELOW 10KT THIS EVENING AS THE DIRECTION SHIFTS TO
PRIMARILY NORTHEAST.
SHIMON
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
651 AM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* IFR CIGS IMPROVING TO MVFR LATE MORNING/MIDDAY WITH SCATTERING
POSSIBLE LATE.
* IFR/MVFR VSBY TO IMPROVE THROUGH THE MORNING.
* -DZ ENDING BY MID MORNING...SOME -FZDZ POSSIBLE WITH TEMPS RIGHT
AROUND FREEZING.
* NORTHEAST WINDS GUSTING TO NEAR 20 KT AT TIMES.
MDB
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE ACROSS CENTRAL INDIANA CONTINUES TO MOVE EAST WITH AN
INVERTED TROUGH AXIS EXTENDING NORTHWARD FROM IT TOWARDS LAKE
MICHIGAN. LOW LEVEL MOISTURE REMAINS ABUNDANT WITH MAINLY IFR CIGS
AND VARIABLE IFR/MVFR VSBY ACROSS THE TERMINALS THIS MORNING.
DEEPER MOISTURE HAS EXITED TO THE SOUTHEAST WITH THE PASSAGE OF AN
UPPER WAVE BUT ENOUGH LIFT REMAINS TO FORCE DEVELOPMENT OF AREAS
OF DRIZZLE AND EVEN FREEZING DRIZZLE WHERE TEMPS ARE AT/BELOW
FREEZING. THE -DZ/-FZDZ WILL WIND DOWN THROUGH MID MORNING WHILE
CEILINGS GRADUALLY IMPROVE AS DRIER LOW LEVEL AIR TRIES TO WORK IN
FROM THE NORTH/NORTHEAST. BIGGEST CHALLENGE BECOMES TIMING CIG
IMPROVEMENTS TO MVFR AND POSSIBLY EVEN LOW END VFR IF ENOUGH DRY
AIR WORKS IN OR BREAKS END UP DEVELOPING LATER IN THE DAY. MAY BE
A BIT ON THE CONSERVATIVE SIDE WITH THE SPEED OF
IMPROVEMENT BUT MANY SITES UPSTREAM HAVE LOWERED TO IFR SO HOLDING
ONTO IT THROUGH THE MORNING SEEMS TO MAKE THE MOST SENSE. THE NEXT
QUESTION BECOMES HOW MUCH CLOUD COVER WILL BE IN PLACE THROUGH
TONIGHT. WILL CONTINUE THE TREND OF THE PREVIOUS FORECASTS WITH
SCATTERED CLOUDS BUT ENOUGH MOISTURE MAY LINGER TO KEEP BKN
COVERAGE...ESPECIALLY IF CLOUD COVER REMAINS BKN-OVC THROUGH
SUNSET. OTHERWISE...WINDS WILL TURN NORTHWESTERLY THIS EVENING
THEN RETURN TO NORTH AND EVENTUALLY NORTHEAST OR EAST-NORTHEAST
BY MID SUNDAY MORNING.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM-HIGH CONFIDENCE IN IFR IMPROVING TO MVFR BUT LOW-MEDIUM
CONFIDENCE IN TIMING.
* HIGH CONFIDENCE IN ANY IFR/MVFR VSBY IMPROVING TO VFR...MEDIUM
CONFIDENCE IN TIMING.
* HIGH CONFIDENCE IN -DZ ENDING BY MID MORNING...WITH MEDIUM-HIGH
CONFIDENCE THAT ANY -FZDZ WOULD BE BRIEF IF IT OCCURS AT ALL.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE OF MIXED PRECIPITATION LATE...MVFR
POSSIBLE.
MONDAY...RAIN/SNOW LIKELY. IFR POSSIBLE.
TUESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
315 AM CDT
LOW PRESSURE CONTINUES TO MOVE EASTWARD ACROSS SOUTHERN ILLINOIS ON
ITS WAY TOWARD THE OHIO RIVER VALLEY AND INTO THE MID ATLANTIC
THROUGH TODAY. AN INVERTED TROUGH EXTENDS NORTH OF THE LOW UP THE
MID/UPPER MISSISSIPPI RIVER VALLEY WHILE HIGH PRESSURE RIDGING
EXTENDS FROM THE CANADIAN PRAIRIES INTO THE CENTRAL PLAINS. THIS
WILL ACT TO TURN WINDS FROM NORTHEAST TO NORTH THROUGH THE MORNING.
AT THE MOMENT...THE STRONGEST SPEEDS...AROUND 25 KT...ARE FOUND
ACROSS THE CENTRAL THIRD OF LAKE MICHIGAN AND THESE LOOK TO EASE
SLIGHTLY THROUGH THE MORNING BUT OVERALL EXPECT 15 TO 20 KT WINDS TO
PREVAIL FROM LATE MORNING THROUGH THE AFTERNOON ACROSS THE SOUTHERN
HALF OF THE LAKE. AS THIS OCCURS...WINDS WILL DIMINISH NORTH AS THE
PRESSURE GRADIENT SLACKENS WITH A SECONDARY RIDGE AXIS EXTENDING
EASTWARD ACROSS CENTRAL ONTARIO. THE MAIN CONCERN FOR TODAY WILL BE
SMALL CRAFT ADVISORY LEVEL WAVES ACROSS THE IL/IN NEARSHORE WATERS
GIVEN THE LENGTHENING FETCH OF WIND AND PERSISTENT SPEEDS. WILL
CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS...WITH WAVES SUBSIDING
THIS EVENING. THE MAIN HIGH PRESSURE AREA WILL SETTLE SOUTHWARD INTO
THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE A SURFACE LOW DROPS
SOUTHEASTWARD ACROSS CENTRAL/EASTERN ONTARIO. THIS WILL RESULT IN
THE PRESSURE GRADIENT INCREASING ACROSS THE LAKE ONCE AGAIN
SUPPORTING AN INCREASE IN WIND SPEEDS THIS EVENING AND
TONIGHT...WITH THE STRONGEST SPEEDS NORTH. THE STRONGER WINDS WILL
BE SHORT LIVED AS HIGH PRESSURE PASSES OVER THE LAKE SUNDAY
RESULTING IN MUCH LIGHTER WINDS WITH A SHIFT TO THE EAST AND
SOUTHEAST LATER IN THE DAY/EVENING AS THE HIGH SHIFTS EAST OF THE
LAKE. WAVES WILL BUILD AS THE WINDS COME UP LATER TONIGHT AND
NEARSHORE AREAS MAY FLIRT WITH SMALL CRAFT ADVISORY LEVEL WAVES FOR
A SHORT TIME LATE SUNDAY MORNING BUT THIS LOOKS MARGINAL RIGHT NOW.
LOW PRESSURE WILL BE TAKING SHAPE ACROSS THE WESTERN DAKOTAS
SUNDAY AND MOVE NORTHEASTWARD ACROSS NORTHERN MINNESOTA MONDAY AND
EVENTUALLY SOUTHERN LAKE SUPERIOR MONDAY NIGHT. THIS TRACK IS A BIT
FURTHER NORTH THAN EARLIER INDICATED. AS THE LOW APPROACHES...SOUTH
TO SOUTHEAST WINDS WILL INCREASE MONDAY THEN TURN SOUTHWEST THEN
NORTHWEST MONDAY NIGHT INTO TUESDAY MORNING. THE FURTHER NORTH TRACK
WOULD ALLOW STRONGER SPEEDS ACROSS MORE OF THE LAKE WITH A PERIOD OF
LOW TO POSSIBLY MID RANGE GALES POSSIBLE ACROSS THE ENTIRE LAKE
STARTING MONDAY NIGHT AND WINDING DOWN BY EARLY TUESDAY
AFTERNOON...THOUGH SPEEDS WILL BE SLOW TO FALL BELOW 30 KT INTO
TUESDAY EVENING. THE LOW WILL SLOW AS IT MOVES INTO QUEBEC EARLY
WEDNESDAY WHILE HIGH PRESSURE SPREADS INTO THE UPPER MIDWEST WHICH
WILL LEAD TO A PERSISTENT NORTHWEST BREEZE THROUGH WEDNESDAY. WINDS
WILL THEN DIMINISH LATER WEDNESDAY AS THE HIGH MOVES OVER THE LAKE
THURSDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 PM SATURDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
414 AM CDT SAT MAR 16 2013
.DISCUSSION...
414 AM CDT
MAIN FORECAST CONCERNS ARE IN THE NEAR TERM WITH FOG/DRIZZLE TRENDS
THROUGH THE REMAINDER OF THE MORNING...WITH CHANCES FOR MIXED
PRECIP/SNOW ONCE AGAIN BY LATE IN THE WEEKEND.
LATEST RADAR IMAGERY DEPICTING BETTER PRECIP AXIS FURTHER TO THE
NORTH/NORTHEAST...WHERE MAINLY LIGHT SNOW SHOWERS ARE ONGOING. PER
LATEST RAP ANALYSIS...THIS PRECIP IS IN RESPONSE TO STRONGER LOW
LEVEL FRONTOGENESIS AS WELL WAA AXIS SITUATED RIGHT TOWARDS THIS
GENERAL LOCATION. THIS IS ONGOING OUT AHEAD OF A MID LEVEL
WAVE DROPPING SOUTHEAST ACROSS THE GREAT LAKES REGION...WITH
INVERTED SURFACE TROUGH EXTENDING UP NORTH THROUGH THE AREA FROM THE
STRONGER AND MORE DEFINED SURFACE REFLECTION ACROSS SOUTH CENTRAL
ILLINOIS. WITH THIS MID LEVEL FEATURE/SURFACE LOW AND TROUGH
SHIFTING EAST/SOUTHEAST ACROSS THE REGION THROUGH THIS MORNING...THE
AFOREMENTIONED FORCING MECHANISMS WILL ALSO SLIDE SOUTHEAST WITH THE
BEST FORCING/PRECIP EXPECTED TO CONTINUE SKIRTING FAR NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH...IT DOES APPEAR THAT
CURRENT PRECIP AXIS WILL STAY OFF TO THE NORTHEAST AND EAST THROUGH
THROUGH THE REMAINDER OF THE MORNING. WITH FAIRLY SATURATED
CONDITIONS...CONTINUE TO MONITOR FOG AND DRIZZLE ACROSS THE CWA THIS
MORNING. OVERALL VISIBILITY IN THIS FOG HAS COME UP WITHIN THE LAST
COUPLE OF HOURS...BUT SOME AREAS ACROSS NORTHWEST INDIANA STILL
OBSERVING FOG WITH VISIBILITY BELOW ONE MILE. DO EXPECT SOME
REMAINING FOG/DRIZZLE TO STILL BE POSSIBLE OVER THE NEXT SEVERAL
HOURS...UNTIL DRIER AIR WORKS IT WAY SOUTH THROUGH THE CWA. OUTSIDE
OF FEW ISOLATED SPOTS IN NORTH CENTRAL ILLINOIS...TEMPS THIS MORNING
HAVE REMAINED AT OR JUST ABOVE FREEZING. THIS WILL CONTINUE TO BE
THE CASE THIS MORNING...WITH ANY WIDESPREAD FREEZING DRIZZLE
UNLIKELY. RAP ANALYSIS WAS INDICATING ANOTHER AREA OF FRONTOGENETICAL
FORCING MOVING EAST JUST SOUTH OF THE AREA. WEAK RETURNS ON RADAR
HAVE BEEN NOTED BUT THIS HAS NOT RESULTED IN MUCH OF ANY
PRECIP...AND DONT EXPECT IT TO FOR THE REMAINDER OF THIS MORNING.
CLOUD COVER SHOULD LINGER FOR MOST OF TODAY WITH TEMPS EXPECTED TO
RANGE FROM THE LOW TO MID 30S ACROSS THE NORTHERN CWA TO AROUND 40
ACROSS THE SOUTHERN CWA...UNTIL TEMPS BEGIN FALLING LATER THIS
AFTERNOON AS MUCH COLDER AIR WORKS ITS WAY SOUTH ACROSS THE REGION.
RELATIVELY QUIET CONDITIONS ARE EXPECTED THIS EVENING AND OVERNIGHT
AS HIGH PRESSURE BUILDS EAST ACROSS THE REGION. LOW LEVEL STRATUS
SHOULD CONTINUE TO DIMINISH OVERNIGHT...BUT WITH THE POSSIBILITY OF
SOME CLOUD COVER SPILLING OFF THE LAKE INTO NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...AND EVEN A STRAY LIGHT SNOW SHOWER TO POSSIBILITY
MOVE ACROSS NORTHWEST INDIANA. FOR THE PRECIP POTENTIAL LATE
SATURDAY NIGHT INTO SUNDAY ACROSS THE SOUTHERN CWA...WITH A MID
LEVEL WAVE AND SURFACE REFLECTION APPROACHING THE MID MISSISSIPPI
VALLEY...DID LOWER POPS AS IT IS APPEARING THAT THIS WILL NOW STAY
TO THE SOUTH FOR THE TIME BEING. HIGH PRESSURE LOOKS TO DOMINATE
MOST OF THE REGION ON SUNDAY WITH RELATIVELY QUIET CONDITIONS IN
PLACE AND TEMPS IN THE LOW TO MID 30S...BUT WITH CLOUD COVER
INCREASING ACROSS THE REGION ONCE AGAIN.
IT DOES APPEAR THAT AS A MID/UPPER LEVEL TROUGH MOVES EAST ACROSS
THE CENTRAL CONUS...IT WILL ALSO BE DIGGING. THIS COULD LIFT
THIS SOUTHERN STREAM WAVE AND PRECIP AXIS FURTHER NORTH WHILE WAA
STRENGTHENS AND LIFTS ACROSS THE SOUTHERN CWA LATE SUNDAY NIGHT INTO
MONDAY. THIS SHOULD ALLOW FOR SOME WARMING AND FOR PRECIP TO BE IN
THE FORM OF A RAIN/SNOW MIX. ALTHOUGH...LATEST GUIDANCE IS
INDICATING THAT ANY PRECIP SHOULD REMAIN ACROSS THE SOUTHERN CWA
DURING THIS TIME. THEN...FORCING FROM WESTERN TROUGH SHOULD BEGIN TO
WORK ITS WAY FROM THE WEST MORE TOWARDS THE MONDAY MORNING TIME
FRAME WITH PRECIP EXPECTED TO SHIFT EAST ACROSS THE CWA.
TEMPERATURES PROFILE WILL BE RATHER WARM WITH A RAIN/SNOW MIX
POSSIBLE EARLY MONDAY...BEFORE ALL RAIN IS EXPECTED ACROSS THE
SOUTHERN TWO THIRDS OF THE CWA. AREAS ACROSS THE NORTHWEST CWA STILL
APPEAR TO OBSERVE ALL SNOW THROUGH MUCH OF MONDAY...BEFORE MUCH
COLDER AIR PUSHES SOUTHEAST ACROSS THE CWA LATE IN THE DAY WITH
PRECIP LIKELY ALL SNOW BY THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* IFR CIG/VIS CONDITIONS EXPECTED TO CONTINUE THROUGH DAYBREAK
WITH IMPROVEMENT BEGINNING AFTER THAT.
* NORTHEAST WINDS 10-15 KT...BECOMING NORTH-NORTHEAST BY MIDDAY
THEN EVENTUALLY DECREASING LATE.
* PERIOD OF DRIZZLE/SNOW AND POSSIBLY FREEZING DRIZZLE POSSIBLE
THROUGH DAYBREAK.
* CIGS IMPROVING TO MVFR BY MID/LATE MORNING.
MDB
//DISCUSSION...UPDATED 09Z...
STEADIER IFR/LIFR CIGS HAVE TAKEN OVER AND EXPECT THESE TO
CONTINUE THROUGH AT LEAST DAYBREAK. DZ/FZDZ STILL A GOOD
POSSIBILITY BUT HAVE NOT SEEN MUCH NOTED IN UPSTREAM OBSERVATIONS
ALTHOUGH THIS IS NOT SURPRISING AS IT IS EXPECTED TO BE VERY
LIGHT. RADAR DOES SHOW SOME WEAK REFLECTIVITY WHICH DOES SUPPORT
ITS PRESENCE UPSTREAM WITH THE WINDOW FOR OCCURRENCE LOCALLY
OPENING UP IN THE NEXT HOUR OR TWO AND CONTINUING THROUGH
DAYBREAK. TIMING OF IMPROVEMENT TO MVFR IS NOT COMPLETELY CLEAR
BUT MID TO LATE MORNING STILL LOOKS REASONABLE.
MDB
FROM 06Z...
A VARIETY OF IFR/MVFR CONDITIONS CONTINUE ACROSS THE AREA WITH THE
MAIN CORRIDOR OF IFR/LIFR CIGS/VSBY STRETCHING FROM SOUTHEAST MN
RIGHT INTO CHICAGO/NW INDIANA. THE TRICKY PART IS THAT MVFR CIGS
AND EVEN VFR VSBY IS BEING REPORTED JUST TO THE NORTH OF THE
TERMINALS ACROSS SOUTHEAST WISCONSIN...WITH MVFR SETTLING INTO
RFD. THE MAIN QUESTION IN THE NEAR TERM WILL BE IF THIS
IMPROVEMENT TO MVFR CAN WORK INTO THE CHI AREA TERMINALS OVER THE
NEXT FEW HOURS. ANOTHER UPPER WAVE IS MOVING SOUTHEASTWARD DRIVING
ANOTHER BATCH OF PRECIPITATION ACROSS CENTRAL/SOUTHEAST WI. THIS
WILL LARGELY REMAIN TO THE NORTH/NORTHEAST OF THE LOCAL TERMINALS
OVER THE NEXT FEW HOURS BUT THIS MAY HELP TO BRING AREAS THAT ARE
MVFR BACK TO IFR. SURFACE ANALYSIS SHOWS THAT SEVERAL SITES IN
EASTERN WI HAVE HAD THEIR CEILING AND VSBY FALL OVER THE LAST FEW
HOURS AND SUSPECT THAT THIS WILL BE THE TREND. SO THERE MAY BE A
SHORT PERIOD OF MVFR IMPROVEMENT BUT STEADIER IFR SHOULD WORK BACK
IN SOON AFTER AND CONTINUE THROUGH DAYBREAK. DRIER AIR WILL MOVE
INTO THE MID LEVELS TOWARD 9/10Z WHILE LOW LEVEL MOISTURE REMAINS
HIGH AND THERE MAY BE ENOUGH LIFT TO RESULT IN DRIZZLE/FREEZING
DRIZZLE AND PERHAPS SOME LIGHT SNOW. SEVERAL UPSTREAM OB SITES
HAVE REPORTED LIGHT FROZEN PRECIP UNDER THE MID LEVEL DRYING. WILL
CONTINUE WITH THIS MENTION IN THE FORECAST THROUGH DAYBREAK WHEN
FORCING BEGINS TO WANE AND THREAT WILL DIMINISH.
WINDS HAVE TURNED A BIT MORE NORTHEAST AND WILL LIKELY FLUCTUATE
BETWEEN NORTH AND NORTHEAST OVERNIGHT AS AN INVERTED TROUGH AXIS
CROSSES THE AREA. DRIER LOW LEVEL AIR LOOKS TO SPREAD IN LATER IN
THE MORNING WHICH IS EXPECTED TO ALLOW IFR TO IMPROVE TO MVFR BUT
DO HAVE SOME QUESTION ABOUT HOW QUICKLY THIS WILL OCCUR.
SCATTERING OF CLOUDS MAY OCCUR DURING THE EARLY EVENING HOURS.
WINDS WILL VARY BETWEEN NORTHWEST AND NORTH SATURDAY EVENING/NIGHT
AS HIGH PRESSURE MOVES IN BUT THERE ARE SIGNS OF ANOTHER WEAK
UPPER DISTURBANCE CROSSING THE AREA WHICH MAY ACT TO BRING AN
INCREASE IN CLOUD COVER. WILL KEEP SCATTERED CLOUDS INTO SUNDAY
MORNING FOR NOW.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM-HIGH CONFIDENCE IN IFR CIGS AND MVFR OR EVEN BRIEF IFR
VSBY CONTINUING THROUGH DAYBREAK.
* MEDIUM CONFIDENCE IN TIMING AND TYPE OF PRECIPITATION THROUGH
DAYBREAK.
* HIGH CONFIDENCE IN WIND TRENDS.
* MEDIUM-HIGH CONFIDENCE IN IMPROVING VSBY AND CIGS BUT LOW-MEDIUM
CONFIDENCE IN TIMING.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...VFR. SLIGHT CHANCE OF SNOW LATE SUNDAY NIGHT.
MONDAY...SNOW/RAIN LIKELY. IFR POSSIBLE.
TUESDAY THROUGH THURSDAY...VFR.
RATZER
&&
.MARINE...
315 AM CDT
LOW PRESSURE CONTINUES TO MOVE EASTWARD ACROSS SOUTHERN ILLINOIS ON
ITS WAY TOWARD THE OHIO RIVER VALLEY AND INTO THE MID ATLANTIC
THROUGH TODAY. AN INVERTED TROUGH EXTENDS NORTH OF THE LOW UP THE
MID/UPPER MISSISSIPPI RIVER VALLEY WHILE HIGH PRESSURE RIDGING
EXTENDS FROM THE CANADIAN PRAIRIES INTO THE CENTRAL PLAINS. THIS
WILL ACT TO TURN WINDS FROM NORTHEAST TO NORTH THROUGH THE MORNING.
AT THE MOMENT...THE STRONGEST SPEEDS...AROUND 25 KT...ARE FOUND
ACROSS THE CENTRAL THIRD OF LAKE MICHIGAN AND THESE LOOK TO EASE
SLIGHTLY THROUGH THE MORNING BUT OVERALL EXPECT 15 TO 20 KT WINDS TO
PREVAIL FROM LATE MORNING THROUGH THE AFTERNOON ACROSS THE SOUTHERN
HALF OF THE LAKE. AS THIS OCCURS...WINDS WILL DIMINISH NORTH AS THE
PRESSURE GRADIENT SLACKENS WITH A SECONDARY RIDGE AXIS EXTENDING
EASTWARD ACROSS CENTRAL ONTARIO. THE MAIN CONCERN FOR TODAY WILL BE
SMALL CRAFT ADVISORY LEVEL WAVES ACROSS THE IL/IN NEARSHORE WATERS
GIVEN THE LENGTHENING FETCH OF WIND AND PERSISTENT SPEEDS. WILL
CONTINUE WITH THE SMALL CRAFT ADVISORY AS-IS...WITH WAVES SUBSIDING
THIS EVENING. THE MAIN HIGH PRESSURE AREA WILL SETTLE SOUTHWARD INTO
THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE A SURFACE LOW DROPS
SOUTHEASTWARD ACROSS CENTRAL/EASTERN ONTARIO. THIS WILL RESULT IN
THE PRESSURE GRADIENT INCREASING ACROSS THE LAKE ONCE AGAIN
SUPPORTING AN INCREASE IN WIND SPEEDS THIS EVENING AND
TONIGHT...WITH THE STRONGEST SPEEDS NORTH. THE STRONGER WINDS WILL
BE SHORT LIVED AS HIGH PRESSURE PASSES OVER THE LAKE SUNDAY
RESULTING IN MUCH LIGHTER WINDS WITH A SHIFT TO THE EAST AND
SOUTHEAST LATER IN THE DAY/EVENING AS THE HIGH SHIFTS EAST OF THE
LAKE. WAVES WILL BUILD AS THE WINDS COME UP LATER TONIGHT AND
NEARSHORE AREAS MAY FLIRT WITH SMALL CRAFT ADVISORY LEVEL WAVES FOR
A SHORT TIME LATE SUNDAY MORNING BUT THIS LOOKS MARGINAL RIGHT NOW.
LOW PRESSURE WILL BE TAKING SHAPE ACROSS THE WESTERN DAKOTAS
SUNDAY AND MOVE NORTHEASTWARD ACROSS NORTHERN MINNESOTA MONDAY AND
EVENTUALLY SOUTHERN LAKE SUPERIOR MONDAY NIGHT. THIS TRACK IS A BIT
FURTHER NORTH THAN EARLIER INDICATED. AS THE LOW APPROACHES...SOUTH
TO SOUTHEAST WINDS WILL INCREASE MONDAY THEN TURN SOUTHWEST THEN
NORTHWEST MONDAY NIGHT INTO TUESDAY MORNING. THE FURTHER NORTH TRACK
WOULD ALLOW STRONGER SPEEDS ACROSS MORE OF THE LAKE WITH A PERIOD OF
LOW TO POSSIBLY MID RANGE GALES POSSIBLE ACROSS THE ENTIRE LAKE
STARTING MONDAY NIGHT AND WINDING DOWN BY EARLY TUESDAY
AFTERNOON...THOUGH SPEEDS WILL BE SLOW TO FALL BELOW 30 KT INTO
TUESDAY EVENING. THE LOW WILL SLOW AS IT MOVES INTO QUEBEC EARLY
WEDNESDAY WHILE HIGH PRESSURE SPREADS INTO THE UPPER MIDWEST WHICH
WILL LEAD TO A PERSISTENT NORTHWEST BREEZE THROUGH WEDNESDAY. WINDS
WILL THEN DIMINISH LATER WEDNESDAY AS THE HIGH MOVES OVER THE LAKE
THURSDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 10 PM SATURDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1012 PM EDT SUN MAR 17 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 353 PM EDT SUN MAR 17 2013
A LOW PRESSURE SYSTEM TRAVERSING THE TENNESSEE VALLEY WILL
CONTINUE TO INITIATE PRECIP ACROSS CENTRAL INDIANA THROUGH
TOMORROW MORNING. RAIN WILL TRANSITION TO A WINTRY MIX TONIGHT
ACROSS THE NORTHERN PORTIONS OF CENTRAL INDIANA. TOMORROW...RAIN
WILL LINGER THROUGH THE MORNING AND THEN TAPER OFF THROUGH THE
COURSE OF THE DAY AS THE LOW PUSHES TO THE EAST. AFTER THAT...HIGH
PRESSURE WILL BRING DRY CONDITIONS TO CENTRAL REMAINDER THROUGH
THE EXTENDED PERIOD.
&&
.NEAR TERM /REST OF TONIGHT/...
ISSUED AT 707 PM EDT SUN MAR 17 2013
FOR 7 PM UPDATE WENT SLIGHTLY SLOWER WITH RAIN ARRIVAL OVER THE NEXT
FEW HOURS TO BETTER MATCH RADAR MOSAIC. WHILE SNOW HAS BEEN BRIEFLY
NOTED UPSTREAM...OBS SHOW MOSTLY RAIN AND THE SITES THAT HAVE
REPORTED SNOW HAVE BEEN RAIN FOR AN HOUR...SNOW FOR ONE
REPORT...THEN BACK TO RAIN SO THINK PREVAILING TYPE IS RAIN AND ANY
SNOW WOULD BE VERY BRIEF. THE EXCEPTION TO THIS IS IN THE NORTH
WHERE CONTINUED WITH A CHANCE FOR RAIN AND SNOW AFTER 1Z. MADE NO
CHANGES OF PREVIOUS FORECAST PRECIP TYPE AFTER 6Z WHEN WINTRY MIX
WAS INTRODUCED IN THE NORTH AS DESCRIBED BELOW. CONSIDERED ADDITION
OF THUNDERSTORMS IN THE SOUTH BASED ON OBS IN EASTERN MISSOURI.
HOWEVER THE CURRENT AREA OF THUNDERSTORMS ON RADAR MATCHES UP NICELY
TO NORTHERN EXTENT OF MUCAPES FROM THE RAP...AND THE RAP KEEPS THIS
AREA OF POSITIVE MUCAPES SOUTH OF THE FORECAST AREA UNTIL AFTER 14Z
MONDAY...AND THIS IS CONSISTENT WITH SIMILAR FIELDS IN GFS AND NAM.
THUS WILL KEEP THUNDER OUT FOR NOW BUT CONTINUE TO MONITOR CLOSELY.
PREVIOUS DISCUSSION FOLLOWS...
ISSUED AT 353 PM EDT SUN MAR 17 2013
THE MAIN FOCUS OF THE NEAR TERM IS WINTRY PRECIP ACROSS THE
NORTHERN COUNTIES TONIGHT.
SURFACE LOW WILL TRACK ACROSS TENNESSEE AND OHIO VALLEYS
TONIGHT...RESULTING IN CONTINUED PRECIP ACROSS ALL OF CENTRAL
INDIANA. FIRST...THE FORECAST AREA IS UNDER A SEE TEXT FOR
THUNDERSTORMS TONIGHT. CONSIDERED ENTERING MENTION OF ISOLATED
STORMS OVER THE SOUTHERN COUNTIES AFTER MON 06Z TONIGHT AS FRONT
AND WARM AIR ADVECTION MAKE SURGE INTO CENTRAL INDIANA.
HOWEVER...AFTER FURTHER CONSIDERATION...IT APPEARS THAT THE BULK
OF CONVECTION SHOULD STAY SOUTH OF FORECAST AREA...AND IF THERE IS
ANY DEVELOPMENT IT SHOULD BE CONFINED TO JUST THE FAR SOUTHERN
COUNTIES. AS A RESULT...THIS CAN BE COVERED WITH FUTURE UPDATES.
THE NORTHERN THIRD OF CENTRAL INDIANA CAN EXPECT A WINTRY MIX OF
RAIN/SNOW STARTING THIS EVENING. HOWEVER...IT GETS KIND OF MESSY
AFTER MIDNIGHT AS WARM AIR ADVECTS INTO THE AREA. ANTICIPATE A
CHANGE TO A RAIN/SLEET MIX AFTER MIDNIGHT FOR A FEW HOURS...AND
THEN RAIN/FREEZING RAIN LATE IN THE NIGHT. MINOR ICE ACCUMULATIONS
WILL BE POSSIBLE.
TEMPS THROUGH THIS EVENING AND TONIGHT WILL FLUCTUATE BETWEEN LOW
TO UPPER 30S...STUCK CLOSE TO ALLBLEND.
&&
.SHORT TERM /TOMORROW THROUGH WEDNESDAY/...
ISSUED AT 353 PM EDT SUN MAR 17 2013
PRECIP WILL TRANSITION BACK TO RAIN AFTER DAYBREAK TOMORROW
MORNING AND TAPER OFF FROM WEST TO EAST THROUGH THE COURSE OF THE
DAY. SLIGHT CHANCE POPS WILL ONLY LINGER OVER THE EASTERN PORTIONS
OF CENTRAL INDIANA INTO TOMORROW EVENING. THE REMAINDER OF THE
FORECAST AREA WILL BE UNDER THE INFLUENCE OF HIGH PRESSURE. THIS
HIGH PRESSURE WILL DOMINATE THE FORECAST WELL INTO THE EXTENDED
PERIOD BRINGING DRY AND COOL CONDITIONS. MODELS HAVE A GOOD HANDLE
ON THE COLD AIR MASS AND BELOW NORMAL TEMPERATURES...SO STUCK
CLOSE TO GUIDANCE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 206 PM EDT SUN MAR 17 2013
ALTHOUGH MODELS ARE HAVING SOME DIFFERENCES ESPECIALLY WITH THE
UPPER PATTERN DAYS 5 THROUGH 7...THE OVERALL PATTERN LOOKS DRY
WITH WELL BELOW NORMAL TEMPERATURES ON TAP UNDER THE INFLUENCE
OF COLD CANADIAN HIGH PRESSURE. INVERTED TROUGH TO MOVE ACROSS THE
SOUTHERN STATES NEXT WEEKEND WILL NEED TO BE WATCHED...HOWEVER...FOR
THE POTENTIAL OF SOME PRECIPITATION REACHING MAINLY OUR SOUTHERN
COUNTIES. BUT...FOR NOW...MODELS AGREE KEEPING IT JUST TO OUR
SOUTH.
REGIONAL INITIALIZATION TEMPERATURES LOOK GOOD WITH HIGHS ONLY IN
THE 30S ON THURSDAY AND THEN MOSTLY 40S THEREAFTER WITH GRADUAL
MODEST WARMING AS THE POLAR AIR MASS LOSES SOME OF ITS PUNCH.
&&
.AVIATION /DISCUSSION FOR 180300Z TAF ISSUANCE/...
ISSUED AT 1012 PM EDT SUN MAR 17 2013
MAKING A FEW CHANGES FOR THE EVENING UPDATE. LIGHT PRECIP HAS
ARRIVED AT BOTH KBMG AND KHUF WITH RADAR TRENDS INDICATING AN UPTICK
IN PRECIP INTENSITY OVER THE LAST HOUR OR SO. KHUF REPORTED LIGHT
SNOW LAST HOUR BUT ANTICIPATE A SHIFT TO RAIN. FOR KIND...START TIME
OF 03Z OR SHORTLY AFTER FOR PRECIP STILL LOOKS GOOD. QUICK GLANCE AT
CURRENT LAPS SOUNDING SUPPORTS PRECIP STARTING AS LIGHT SNOW AT KIND
BUT WARMING IN THE LOW LEVELS SHOULD ENABLE A QUICK TRANSITION TO
RAIN BY 04Z...SIMILAR TO WHAT HAPPENED AT KBMG AND KHUF. ONLY OTHER
BIG CHANGE WAS TO DELAY PRECIP ONSET AT KLAF UNTIL 05Z.
00Z DISCUSSION FOLLOWS.
VERY POOR FLYING CONDITIONS ANTICIPATED THROUGHOUT THE PERIOD...
WITH IFR AND LOWER CONDITIONS DEVELOPING AFTER MIDNIGHT AND
PERSISTING THROUGH EARLY AFTERNOON MONDAY.
PRECIP EXPANDING BACK NORTHEAST INTO THE REGION EARLY THIS EVENING
AHEAD OF LOW PRESSURE LOCATED OVER NORTHEAST TEXAS. LIGHT RAIN
WILL START AROUND OR SHORTLY AFTER 00Z AT KBMG. DRIER AIR THROUGH
THE BOUNDARY LAYER NEEDS TO SATURATE FROM I-70 NORTH HOWEVER...
WITH PRECIPITATION LIKELY STARTING AT KHUF AND KIND OVER THE NEXT
COUPLE HOURS. COULD SEE A VERY BRIEF PERIOD OF SNOW TO BEGIN AT
BOTH KHUF AND KIND THIS EVENING...LIKELY LESS THAN AN HOUR...AS
EVAPORATIVE COOLING TAKES PLACE. BEYOND THAT HOWEVER...PRECIP TYPE
SHOULD TRANSITION TO ALL RAIN AS PROGRESSIVELY WARMER AIR
OVERSPREADS THE BOUNDARY LAYER COURTESY OF A STRONG LOW LEVEL JET
NOSING INTO THE OHIO VALLEY. AT KLAF...AIR IS EVEN DRIER AND
POTENTIAL STILL EXISTS FOR A BRIEF PERIOD WITH SURFACE
TEMPERATURES AROUND FREEZING BEFORE WARM ADVECTION BEGINS TO EXERT
ITS INFLUENCE. LOW LEVEL THERMALS ARE MUCH MORE SUPPORTIVE OF A
MIXTURE OF RAIN/ICE PELLETS AND POSSIBLY EVEN A FEW SNOWFLAKES...
BEFORE THE PRECIP TYPE SHIFTS TO ALL RAIN AFTER 06Z.
IFR AND LOWER CEILINGS WILL DEVELOP OVERNIGHT WITH THE ONSET OF
THE HEAVIER PRECIPITATION...POSSIBLY DROPPING BELOW 500FT TOWARDS
DAYBREAK. PREDOMINANT EASTERLY FLOW THROUGH THE NIGHT WILL VEER TO
SOUTHEAST MONDAY MORNING...BEFORE FLIPPING TO SOUTHWEST BY MIDDAY
AS THE LOW PASSES THROUGH THE REGION. LIGHTER RAIN WILL PERSIST
THROUGH THE MORNING AS WELL...WITH RAIN BECOMING MORE SCATTERED BY
EARLY AFTERNOON AS COLD ADVECTION TAKES HOLD. CEILINGS WILL SLOWLY
LIFT TO LOW MVFR LEVELS AS THE AFTERNOON PROGRESSES...WITH
WESTERLY WINDS GUSTING AT 20-25KTS.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...TDUD
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
730 PM EDT SUN MAR 17 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 353 PM EDT SUN MAR 17 2013
A LOW PRESSURE SYSTEM TRAVERSING THE TENNESSEE VALLEY WILL
CONTINUE TO INITIATE PRECIP ACROSS CENTRAL INDIANA THROUGH
TOMORROW MORNING. RAIN WILL TRANSITION TO A WINTRY MIX TONIGHT
ACROSS THE NORTHERN PORTIONS OF CENTRAL INDIANA. TOMORROW...RAIN
WILL LINGER THROUGH THE MORNING AND THEN TAPER OFF THROUGH THE
COURSE OF THE DAY AS THE LOW PUSHES TO THE EAST. AFTER THAT...HIGH
PRESSURE WILL BRING DRY CONDITIONS TO CENTRAL REMAINDER THROUGH
THE EXTENDED PERIOD.
&&
.NEAR TERM /REST OF TONIGHT/...
ISSUED AT 707 PM EDT SUN MAR 17 2013
FOR 7 PM UPDATE WENT SLIGHTLY SLOWER WITH RAIN ARRIVAL OVER THE NEXT
FEW HOURS TO BETTER MATCH RADAR MOSAIC. WHILE SNOW HAS BEEN BRIEFLY
NOTED UPSTREAM...OBS SHOW MOSTLY RAIN AND THE SITES THAT HAVE
REPORTED SNOW HAVE BEEN RAIN FOR AN HOUR...SNOW FOR ONE
REPORT...THEN BACK TO RAIN SO THINK PREVAILING TYPE IS RAIN AND ANY
SNOW WOULD BE VERY BRIEF. THE EXCEPTION TO THIS IS IN THE NORTH
WHERE CONTINUED WITH A CHANCE FOR RAIN AND SNOW AFTER 1Z. MADE NO
CHANGES OF PREVIOUS FORECAST PRECIP TYPE AFTER 6Z WHEN WINTRY MIX
WAS INTRODUCED IN THE NORTH AS DESCRIBED BELOW. CONSIDERED ADDITION
OF THUNDERSTORMS IN THE SOUTH BASED ON OBS IN EASTERN MISSOURI.
HOWEVER THE CURRENT AREA OF THUNDERSTORMS ON RADAR MATCHES UP NICELY
TO NORTHERN EXTENT OF MUCAPES FROM THE RAP...AND THE RAP KEEPS THIS
AREA OF POSITIVE MUCAPES SOUTH OF THE FORECAST AREA UNTIL AFTER 14Z
MONDAY...AND THIS IS CONSISTENT WITH SIMILAR FIELDS IN GFS AND NAM.
THUS WILL KEEP THUNDER OUT FOR NOW BUT CONTINUE TO MONITOR CLOSELY.
PREVIOUS DISCUSSION FOLLOWS...
ISSUED AT 353 PM EDT SUN MAR 17 2013
THE MAIN FOCUS OF THE NEAR TERM IS WINTRY PRECIP ACROSS THE
NORTHERN COUNTIES TONIGHT.
SURFACE LOW WILL TRACK ACROSS TENNESSEE AND OHIO VALLEYS
TONIGHT...RESULTING IN CONTINUED PRECIP ACROSS ALL OF CENTRAL
INDIANA. FIRST...THE FORECAST AREA IS UNDER A SEE TEXT FOR
THUNDERSTORMS TONIGHT. CONSIDERED ENTERING MENTION OF ISOLATED
STORMS OVER THE SOUTHERN COUNTIES AFTER MON 06Z TONIGHT AS FRONT
AND WARM AIR ADVECTION MAKE SURGE INTO CENTRAL INDIANA.
HOWEVER...AFTER FURTHER CONSIDERATION...IT APPEARS THAT THE BULK
OF CONVECTION SHOULD STAY SOUTH OF FORECAST AREA...AND IF THERE IS
ANY DEVELOPMENT IT SHOULD BE CONFINED TO JUST THE FAR SOUTHERN
COUNTIES. AS A RESULT...THIS CAN BE COVERED WITH FUTURE UPDATES.
THE NORTHERN THIRD OF CENTRAL INDIANA CAN EXPECT A WINTRY MIX OF
RAIN/SNOW STARTING THIS EVENING. HOWEVER...IT GETS KIND OF MESSY
AFTER MIDNIGHT AS WARM AIR ADVECTS INTO THE AREA. ANTICIPATE A
CHANGE TO A RAIN/SLEET MIX AFTER MIDNIGHT FOR A FEW HOURS...AND
THEN RAIN/FREEZING RAIN LATE IN THE NIGHT. MINOR ICE ACCUMULATIONS
WILL BE POSSIBLE.
TEMPS THROUGH THIS EVENING AND TONIGHT WILL FLUCTUATE BETWEEN LOW
TO UPPER 30S...STUCK CLOSE TO ALLBLEND.
&&
.SHORT TERM /TOMORROW THROUGH WEDNESDAY/...
ISSUED AT 353 PM EDT SUN MAR 17 2013
PRECIP WILL TRANSITION BACK TO RAIN AFTER DAYBREAK TOMORROW
MORNING AND TAPER OFF FROM WEST TO EAST THROUGH THE COURSE OF THE
DAY. SLIGHT CHANCE POPS WILL ONLY LINGER OVER THE EASTERN PORTIONS
OF CENTRAL INDIANA INTO TOMORROW EVENING. THE REMAINDER OF THE
FORECAST AREA WILL BE UNDER THE INFLUENCE OF HIGH PRESSURE. THIS
HIGH PRESSURE WILL DOMINATE THE FORECAST WELL INTO THE EXTENDED
PERIOD BRINGING DRY AND COOL CONDITIONS. MODELS HAVE A GOOD HANDLE
ON THE COLD AIR MASS AND BELOW NORMAL TEMPERATURES...SO STUCK
CLOSE TO GUIDANCE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 206 PM EDT SUN MAR 17 2013
ALTHOUGH MODELS ARE HAVING SOME DIFFERENCES ESPECIALLY WITH THE
UPPER PATTERN DAYS 5 THROUGH 7...THE OVERALL PATTERN LOOKS DRY
WITH WELL BELOW NORMAL TEMPERATURES ON TAP UNDER THE INFLUENCE
OF COLD CANADIAN HIGH PRESSURE. INVERTED TROUGH TO MOVE ACROSS THE
SOUTHERN STATES NEXT WEEKEND WILL NEED TO BE WATCHED...HOWEVER...FOR
THE POTENTIAL OF SOME PRECIPITATION REACHING MAINLY OUR SOUTHERN
COUNTIES. BUT...FOR NOW...MODELS AGREE KEEPING IT JUST TO OUR
SOUTH.
REGIONAL INITIALIZATION TEMPERATURES LOOK GOOD WITH HIGHS ONLY IN
THE 30S ON THURSDAY AND THEN MOSTLY 40S THEREAFTER WITH GRADUAL
MODEST WARMING AS THE POLAR AIR MASS LOSES SOME OF ITS PUNCH.
&&
.AVIATION /DISCUSSION FOR 180000Z TAF ISSUANCE/...
ISSUED AT 730 PM EDT SUN MAR 17 2013
VERY POOR FLYING CONDITIONS ANTICIPATED THROUGHOUT THE PERIOD...
WITH IFR AND LOWER CONDITIONS DEVELOPING AFTER MIDNIGHT AND
PERSISTING THROUGH EARLY AFTERNOON MONDAY.
PRECIP EXPANDING BACK NORTHEAST INTO THE REGION EARLY THIS EVENING
AHEAD OF LOW PRESSURE LOCATED OVER NORTHEAST TEXAS. LIGHT RAIN
WILL START AROUND OR SHORTLY AFTER 00Z AT KBMG. DRIER AIR THROUGH
THE BOUNDARY LAYER NEEDS TO SATURATE FROM I-70 NORTH HOWEVER...
WITH PRECIPITATION LIKELY STARTING AT KHUF AND KIND OVER THE NEXT
COUPLE HOURS. COULD SEE A VERY BRIEF PERIOD OF SNOW TO BEGIN AT
BOTH KHUF AND KIND THIS EVENING...LIKELY LESS THAN AN HOUR...AS
EVAPORATIVE COOLING TAKES PLACE. BEYOND THAT HOWEVER...PRECIP TYPE
SHOULD TRANSITION TO ALL RAIN AS PROGRESSIVELY WARMER AIR
OVERSPREADS THE BOUNDARY LAYER COURTESY OF A STRONG LOW LEVEL JET
NOSING INTO THE OHIO VALLEY. AT KLAF...AIR IS EVEN DRIER AND
POTENTIAL STILL EXISTS FOR A BRIEF PERIOD WITH SURFACE
TEMPERATURES AROUND FREEZING BEFORE WARM ADVECTION BEGINS TO EXERT
ITS INFLUENCE. LOW LEVEL THERMALS ARE MUCH MORE SUPPORTIVE OF A
MIXTURE OF RAIN/ICE PELLETS AND POSSIBLY EVEN A FEW SNOWFLAKES...
BEFORE THE PRECIP TYPE SHIFTS TO ALL RAIN AFTER 06Z.
IFR AND LOWER CEILINGS WILL DEVELOP OVERNIGHT WITH THE ONSET OF
THE HEAVIER PRECIPITATION...POSSIBLY DROPPING BELOW 500FT TOWARDS
DAYBREAK. PREDOMINANT EASTERLY FLOW THROUGH THE NIGHT WILL VEER TO
SOUTHEAST MONDAY MORNING...BEFORE FLIPPING TO SOUTHWEST BY MIDDAY
AS THE LOW PASSES THROUGH THE REGION. LIGHTER RAIN WILL PERSIST
THROUGH THE MORNING AS WELL...WITH RAIN BECOMING MORE SCATTERED BY
EARLY AFTERNOON AS COLD ADVECTION TAKES HOLD. CEILINGS WILL SLOWLY
LIFT TO LOW MVFR LEVELS AS THE AFTERNOON PROGRESSES...WITH
WESTERLY WINDS GUSTING AT 20-25KTS.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...TDUD
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
707 PM EDT SUN MAR 17 2013
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 353 PM EDT SUN MAR 17 2013
A LOW PRESSURE SYSTEM TRAVERSING THE TENNESSEE VALLEY WILL
CONTINUE TO INITIATE PRECIP ACROSS CENTRAL INDIANA THROUGH
TOMORROW MORNING. RAIN WILL TRANSITION TO A WINTRY MIX TONIGHT
ACROSS THE NORTHERN PORTIONS OF CENTRAL INDIANA. TOMORROW...RAIN
WILL LINGER THROUGH THE MORNING AND THEN TAPER OFF THROUGH THE
COURSE OF THE DAY AS THE LOW PUSHES TO THE EAST. AFTER THAT...HIGH
PRESSURE WILL BRING DRY CONDITIONS TO CENTRAL REMAINDER THROUGH
THE EXTENDED PERIOD.
&&
.NEAR TERM /REST OF TONIGHT/...
ISSUED AT 707 PM EDT SUN MAR 17 2013
FOR 7 PM UPDATE WENT SLIGHTLY SLOWER WITH RAIN ARRIVAL OVER THE NEXT
FEW HOURS TO BETTER MATCH RADAR MOSAIC. WHILE SNOW HAS BEEN BRIEFLY
NOTED UPSTREAM...OBS SHOW MOSTLY RAIN AND THE SITES THAT HAVE
REPORTED SNOW HAVE BEEN RAIN FOR AN HOUR...SNOW FOR ONE
REPORT...THEN BACK TO RAIN SO THINK PREVAILING TYPE IS RAIN AND ANY
SNOW WOULD BE VERY BRIEF. THE EXCEPTION TO THIS IS IN THE NORTH
WHERE CONTINUED WITH A CHANCE FOR RAIN AND SNOW AFTER 1Z. MADE NO
CHANGES OF PREVIOUS FORECAST PRECIP TYPE AFTER 6Z WHEN WINTRY MIX
WAS INTRODUCED IN THE NORTH AS DESCRIBED BELOW. CONSIDERED ADDITION
OF THUNDERSTORMS IN THE SOUTH BASED ON OBS IN EASTERN MISSOURI.
HOWEVER THE CURRENT AREA OF THUNDERSTORMS ON RADAR MATCHES UP NICELY
TO NORTHERN EXTENT OF MUCAPES FROM THE RAP...AND THE RAP KEEPS THIS
AREA OF POSITIVE MUCAPES SOUTH OF THE FORECAST AREA UNTIL AFTER 14Z
MONDAY...AND THIS IS CONSISTENT WITH SIMILAR FIELDS IN GFS AND NAM.
THUS WILL KEEP THUNDER OUT FOR NOW BUT CONTINUE TO MONITOR CLOSELY.
PREVIOUS DISCUSSION FOLLOWS...
ISSUED AT 353 PM EDT SUN MAR 17 2013
THE MAIN FOCUS OF THE NEAR TERM IS WINTRY PRECIP ACROSS THE
NORTHERN COUNTIES TONIGHT.
SURFACE LOW WILL TRACK ACROSS TENNESSEE AND OHIO VALLEYS
TONIGHT...RESULTING IN CONTINUED PRECIP ACROSS ALL OF CENTRAL
INDIANA. FIRST...THE FORECAST AREA IS UNDER A SEE TEXT FOR
THUNDERSTORMS TONIGHT. CONSIDERED ENTERING MENTION OF ISOLATED
STORMS OVER THE SOUTHERN COUNTIES AFTER MON 06Z TONIGHT AS FRONT
AND WARM AIR ADVECTION MAKE SURGE INTO CENTRAL INDIANA.
HOWEVER...AFTER FURTHER CONSIDERATION...IT APPEARS THAT THE BULK
OF CONVECTION SHOULD STAY SOUTH OF FORECAST AREA...AND IF THERE IS
ANY DEVELOPMENT IT SHOULD BE CONFINED TO JUST THE FAR SOUTHERN
COUNTIES. AS A RESULT...THIS CAN BE COVERED WITH FUTURE UPDATES.
THE NORTHERN THIRD OF CENTRAL INDIANA CAN EXPECT A WINTRY MIX OF
RAIN/SNOW STARTING THIS EVENING. HOWEVER...IT GETS KIND OF MESSY
AFTER MIDNIGHT AS WARM AIR ADVECTS INTO THE AREA. ANTICIPATE A
CHANGE TO A RAIN/SLEET MIX AFTER MIDNIGHT FOR A FEW HOURS...AND
THEN RAIN/FREEZING RAIN LATE IN THE NIGHT. MINOR ICE ACCUMULATIONS
WILL BE POSSIBLE.
TEMPS THROUGH THIS EVENING AND TONIGHT WILL FLUCTUATE BETWEEN LOW
TO UPPER 30S...STUCK CLOSE TO ALLBLEND.
&&
.SHORT TERM /TOMORROW THROUGH WEDNESDAY/...
ISSUED AT 353 PM EDT SUN MAR 17 2013
PRECIP WILL TRANSITION BACK TO RAIN AFTER DAYBREAK TOMORROW
MORNING AND TAPER OFF FROM WEST TO EAST THROUGH THE COURSE OF THE
DAY. SLIGHT CHANCE POPS WILL ONLY LINGER OVER THE EASTERN PORTIONS
OF CENTRAL INDIANA INTO TOMORROW EVENING. THE REMAINDER OF THE
FORECAST AREA WILL BE UNDER THE INFLUENCE OF HIGH PRESSURE. THIS
HIGH PRESSURE WILL DOMINATE THE FORECAST WELL INTO THE EXTENDED
PERIOD BRINGING DRY AND COOL CONDITIONS. MODELS HAVE A GOOD HANDLE
ON THE COLD AIR MASS AND BELOW NORMAL TEMPERATURES...SO STUCK
CLOSE TO GUIDANCE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 206 PM EDT SUN MAR 17 2013
ALTHOUGH MODELS ARE HAVING SOME DIFFERENCES ESPECIALLY WITH THE
UPPER PATTERN DAYS 5 THROUGH 7...THE OVERALL PATTERN LOOKS DRY
WITH WELL BELOW NORMAL TEMPERATURES ON TAP UNDER THE INFLUENCE
OF COLD CANADIAN HIGH PRESSURE. INVERTED TROUGH TO MOVE ACROSS THE
SOUTHERN STATES NEXT WEEKEND WILL NEED TO BE WATCHED...HOWEVER...FOR
THE POTENTIAL OF SOME PRECIPITATION REACHING MAINLY OUR SOUTHERN
COUNTIES. BUT...FOR NOW...MODELS AGREE KEEPING IT JUST TO OUR
SOUTH.
REGIONAL INITIALIZATION TEMPERATURES LOOK GOOD WITH HIGHS ONLY IN
THE 30S ON THURSDAY AND THEN MOSTLY 40S THEREAFTER WITH GRADUAL
MODEST WARMING AS THE POLAR AIR MASS LOSES SOME OF ITS PUNCH.
&&
.AVIATION /DISCUSSION FOR THE 172100Z TAF ISSUANCE/...
ISSUED AT 446 PM EDT SUN MAR 17 2013
NO CHANGES TO 21Z UPDATE. PRECIP TIMING STILL LOOKS ON
SCHEDULE...POSSIBLY A TOUCH FASTER ON THE ARRIVAL AT KBMG. WILL
MONITOR TRENDS AND ADJUST AS NECESSARY.
18Z UPDATE FOLLOWS.
PRECIPITATION SHIELD SHOULD REACH BMG BY ISSUANCE TIME...HUF AROUND
22Z AND IND AND LAF AFTER 02Z TONIGHT AND TRANSITIONING FROM RAIN OR
SNOW TO ALL RAIN AFTER 22Z AT BMG AND AFTER 06Z AT THE OTHER SITES.
WOULD ALSO NOT RULE OUT A BRIEF PERIOD OF FREEZING RAIN TOWARD 12Z
ESPECIALLY AT LAF...BUT SHOULD BE BRIEF ENOUGH NOT TO MENTION AT
THIS TIME. MEANWHILE...MVFR CONDITIONS EXPECTED TO BECOME IFR OR
WORSE AFTER 06Z. THE RAIN SHOULD THEN END AFTER 15Z AS APPROACHING
LOW PRESSURE SYSTEM MOVES THROUGH. EAST WINDS AROUND 10 KNOTS WILL
BECOME SOUTHWEST OR WEST FOLLOWING THE PASSAGE OF THIS SYSTEM ON
MONDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...TDUD
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...MK/RYAN
AREA FORECAST DISCUSSION...UPDATED
NWS PITTSBURGH PA
612 PM EDT SAT MAR 16 2013
.SYNOPSIS...
PATCHY DRIZZLE AND FOG FOR THE REST OF THE EVENING...AS A COLD
FRONT SAGS SOUTH OF THE REGION. HIGH PRESSURE WILL BUILD OVERHEAD
BRIEFLY SUNDAY BEFORE STRONG LOW PRESSURE BRINGS THE CHANCE FOR
MIXED PRECIPITATION TO THE REGION SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
HAVE UPDATED TO MAKE ADJUSTMENTS TO OVERNIGHT LOWS...SKEWED TOWARD
LATEST LAMP NUMBERS. ALSO ADDED THEM MENTION OF DRIZZLE AND FOG
FOR THE EVENING...WITH DENSE FOG IN THE HIGHER ELEVATIONS.
PREVIOUS DISCUSSION...
SHOWERS ASSOCIATED WITH BOUNDARY CURRENTLY DRAPED OVER THE REGION
WILL CONTINUE TO SAG SOUTH THROUGH THE AFTERNOON. TEMPERATURES
HAVE REACHED THE MID TO UPPER 50`S OVER THE SOUTHERN HALF OF THE
COUNTY WARNING AREA WHILE TEMPERATURES REMAIN JUST AROUND FREEZING
TO THE NORTH. TEMPERATURES WILL BEGIN TO DECLINE AS THE DAY WEARS
ON AND COLD ADVECTION TAKES OVER. ADJUSTED THE DIURNAL CURVE BASED
OFF OF THE HRRR AND LAMP AS THESE GUIDANCE VALUES REPRESENTED THE
TEMPERATURE TREND QUITE WELL THIS MORNING.
HIGH PRESSURE WILL GRADUALLY BUILD SOUTHWARD BEHIND THE FRONT
OVERNIGHT. WITH NORTHWEST FLOW AND COLD ADVECTION CONTINUING...
THINK CLOUD COVER WILL REMAIN...WHICH SHOULD KEEP TEMPERATURES
FROM DROPPING TOO DRASTICALLY. AS SUCH...KEPT TEMPERATURES NEAR MOS
GUIDANCE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
WHILE THE NEWEST RUNS OF THE DETERMINISTIC MODELS HAVE A BETTER
HANDLE ON THE PLACEMENT OF THE STATIONARY BOUNDARY ON
SUNDAY...INHERENT DIFFERENCES IN THE ATMOSPHERIC PROFILES CONTINUE
TO OWE TO LOW FORECAST CONFIDENCE. THE GFS AND NAM LINE UP BETTER
THAN THE PREVIOUS DAYS...BOTH BECOMING SIGNIFICANTLY COLDER AT THE
LOWER LEVELS. THIS HAS SIGNIFICANT IMPACT ON THE SNOW AND MIXED
PRECIPITATION FORECAST AS THE BOUNDARY LIFTS NORTHWARD AS A
WARM FRONT SUNDAY NIGHT. AS IT STANDS RIGHT NOW...MODEL PROFILES
HAVE A PROLONGED PERIOD OF SNOW/MIXED PRECIP ESPECIALLY IN THE
HIGHER ELEVATIONS OF WV/MD. HOWEVER...A LOT WILL DEPEND ON
TEMPERATURES....ESPECIALLY CONSIDERING HOW WARM THOSE LOCATIONS
GOT TODAY - MID 50`S AND HOW WARM WE GET DURING THE DAY SUNDAY
. AT THIS POINT...REMAINED CLOSE TO GUIDANCE FOR THE HIGH
TEMPERATURES SUNDAY BUT IF CLOUD COVER BREAKS AT ALL...WHICH IS
SUGGESTED IN ALL THE MODELS...THE WARM MARCH SUN COULD HAVE A
DRASTIC EFFECT ON LATER PRECIPITATION FORECASTS.
THE OTHER QUESTION IS THE EXTENT OF THE LOW LEVEL MIXING AND WARM
ADVECTION. AT THIS POINT...THERE SEEMS TO BE A BIT OF A COLD AIR
DAMMING SITUATION SUGGESTED BY ALL THE MODELS...LEADING TO
EASTERLY UPSLOPE FLOW OUT AHEAD OF THE APPROACHING SURFACE LOW
OVERNIGHT SUNDAY AND MONDAY MORNING. THIS COULD MAINTAIN SNOW IN
THE EASTERN FACING SLOPES WHILE THE WESTERN FACING SLOPES MAINLY
EXPERIENCE RAIN. IN ADDITION...WITH THE SLOWER PROGRESSION OF THE
FRONTAL BOUNDARY TO THE NORTH...THIS COULD GIVE POINTS NORTH OF
I-80 THAT REMAINED JUST NEAR FREEZING TODAY...TIME TO WARM BEFORE
ANY FROZEN PRECIPITATION COULD HAVE IMPACT. NEEDLESS TO SAY...THIS
IS A COMPLICATED FORECAST SITUATION...OWING TO SEVERAL FACTORS
NEEDING TO LINE UP FOR SNOW AND ICE TO HAVE THE IMPACT THIS LATE
IN THE SEASON. FOR NOW AND AFTER COORDINATION WITH OTHER LOCAL
OFFICES...HAVE MAINTAINED THE MENTION OF FREEZING RAIN AND SNOW
IN THE HAZARDOUS WEATHER OUTLOOK AND WILL LET FUTURE SHIFTS
EVALUATE WITH NEWER MODEL GUIDANCE.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
A DEEPENING TROUGH OVER THE NORTHERN PLAINS WILL SWING A COLD
FRONT ACROSS THE REGION BY EARLY TUESDAY. WITH BETTER CONFIDENCE
IN THE TIMING OF THIS SYSTEM...CONTINUED THE LIKELY POPS THROUGH
TUESDAY MORNING WITH RAIN QUICKLY CHANGING TO SNOW SHOWERS BEHIND
THE FRONTAL PASSAGE TUESDAY AFTERNOON. COLD NORTHWEST FLOW WILL
CONTINUE AT LEAST THE CHANCE FOR SNOW SHOWERS THROUGH TUESDAY
NIGHT. A DEEP UPPER LEVEL TROUGH WILL REMAIN OVER THE EASTERN
CONUS THROUGH THE REST OF THE WEEK KEEPING TEMPERATURES BELOW
SEASONAL AVERAGES THROUGH THE REST OF THE PERIOD.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
A SURFACE LOW WILL PUSH EAST OF THE AREA...PULLING THE FRONTAL
BOUNDARY THAT HAS BEEN DRAPED ACROSS THE AREA SOUTHWARD TONIGHT.
LOW-LEVEL MOISTURE ASSOCIATED WITH THIS SYSTEM WILL CONTINUE TO
BRING PREVAILING IFR CEILINGS AND IFR VISIBILITIES AT TIMES NORTH
OF A KZZV-KMGW LINE...WITH MVFR SOUTHWARD. AS THE FRONT SLIDES
SOUTHWARD...WINDS AT 5 TO 10KTS WILL SHIFT TO MORE NORTHERLY THIS
EVENING.
THE BIGGEST UNCERTAINTY IN THE FORECAST IS HOW LONG IFR
CEILINGS WILL LINGER. FORECAST IS OPTIMISTIC BASED OFF OF UPSTREAM
OBSERVATIONS AND LAMP GUIDANCE...INDICATING THAT CEILINGS WILL
LIFT TO MVFR OVERNIGHT. HOWEVER...AN ALTERNATIVE SCENARIO IS THAT
LOCATIONS NORTH OF KMGW/KZZV REMAIN IFR THROUGH THE OVERNIGHT.
MVFR CEILINGS WILL FINALLY LIFT TO VFR AS HIGH PRESSURE BUILDS IN
FROM THE NORTHWEST ON SUNDAY.
.OUTLOOK.../SUNDAY THROUGH THURSDAY/...
RESTRICTIONS ARE POSSIBLE ALONG WITH A WINTRY MIX OF
RAIN...SNOW...AND FREEZING RAIN EARLY MONDAY. PRECIPITATION WILL
CHANGE TO ALL RAIN ON MONDAY BEFORE A COLD FRONT USHERS COLDER AIR IN
FROM THE NORTHWEST AND ALLOWS FOR PRECIPITATION TO CHANGE OVER TO
SNOW SHOWERS MONDAY NIGHT. A NORTHWESTERLY FLOW IN THE WAKE OF THE
FRONT WILL THEN ALLOW FOR CEILINGS RESTRICTIONS WITH THE SLIGHT
CHANCE OF RAIN AND SNOW SHOWERS TUESDAY INTO THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
156 PM EDT SAT MAR 16 2013
.SYNOPSIS...
AREAS OF RAIN AND SNOW WILL CONTINUE THIS MORNING...THEN DIMINISH
THROUGH THE AFTERNOON AS A COLD FRONT SAGS ACROSS THE REGION.
STRONG LOW PRESSURE IS EXPECTED TO GENERATE MIXED PRECIPITATION ON
SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST MESOANALYSIS INDICATES STRONG LOW LEVEL FRONTOGENESIS OUT
AHEAD OF THE SURFACE LOW THAT IS TRAVERSING OHIO THIS MORNING.
THIS...COUPLED WITH ASSISTANCE FROM THE LEFT EXIT REGION OF A JET
STREAK ALOFT IS PROVIDING FOR THE BETTER SNOW RATES THAT HAVE BEEN
FOCUSED MAINLY NORTH OF I-80 THIS MORNING DESPITE MEAGER MOISTURE. WHILE
MOST OF THIS LIFT IS CONCENTRATED BELOW OPTIMAL SNOW GROWTH
LAYER...THE DYNAMICS OF THE SYSTEM SEEM TO BE WINNING OUT. STILL
WITH THE HIGH SUN ANGLE FOR MID MARCH...EXPECT THAT THE BOUNDARY
LAYER WILL EVENTUALLY WARM...MAKING IT LESS LIKELY FOR SNOW TO
STICK. WILL CONTINUE TO HIGHLIGHT ANY LOCALIZED SNOW CONCERNS VIA
SPS TODAY.
AS THE FRONT CONTINUES TO TIGHTEN OVER THE REGION...WHICH IS ALSO
IMPLIED BY THE SIGNIFICANT TEMPERATURE DIFFERENCE FROM NORTH TO
SOUTH...THINK TEMPERATURES COULD EASILY RISE INTO THE MID 50`S IN
THE SOUTH PER THE MOST RECENT HRRR GUIDANCE.
THE FRONT WILL GRADUALLY SHIFT TO THE SOUTH AND THE LOW WILL
DEPART TO THE EAST...ENDING PRECIPITATION BY THIS EVENING. HIGH
PRESSURE BUILDING SOUTHWARD FROM CANADA WILL KEEP THE FRONTAL
BOUNDARY SOUTH OF THE REGION TONIGHT AND SUNDAY.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
SUNDAY CONTS TO LK DRY FOR MOST COUNTIES AS MDLS HAVE MAINTAINED
PROGNOSIS OF SUFFICIENT SWD PROGRESS OF THE FRONTAL BNDRY. THE
EXCEPTION MAY BE FOR AREAS TO THE SOUTH OF I 68 WHERE SMALL POPS
WERE MAINTAINED DUE TO FRONT PROXIMITY. TEMPS WERE FORECAST WELL
BELOW THE AVERAGES WITH SFC HIGH PRES SETTLING OVR THE AREA...BUT
USING WARMER SREF GUIDANCE.
VARIOUS MDLS PREDICTABLY HANDLES THE APPRCH OF LOW PRES UP THE OH
VALLEY DIFFERENTLY FOR THE SUN NGT AND MONDAY PERIOD. WITH THE
DVLPMNT OF WARM ADVCTN AHEAD OF THE APPRCHG LOW...AND THE
ENTRENCHMENT OF COLD...DRY AIR VIA SFC HIGH PRES...CONFIDENCE IN A
MIXED PCPN EVENT IS RISING FOLLOWING A PD OF INITIAL SN. THAT
POTENTIAL INCLUDES FZRA AND WL MAKE MENTION IN THE HAZARDOUS WEA
OUTLOOK. THE FORECAST WAS BASED ON THE TRACK CONSTRUCTED BY THE
GFS...WHICH RMNS CLOSE TO YSTRDAS PROGNOSIS. GIVEN THAT SCENARIO...PCPN
IS EXPECTED TO CHANGE TO RAIN BY AFTN AS WARM ADVCTN DRIVES HIGH
TEMPS TWD THE CLIMATOLOGICAL NORMALS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A DEEPENING TROUGH OVER THE NORTHERN PLAINS WILL SWING A COLD
FRONT ACROSS THE REGION BY EARLY TUESDAY. WITH BETTER CONFIDENCE
IN THE TIMING OF THIS SYSTEM...CONTINUED THE LIKELY POPS THROUGH
TUESDAY MORNING WITH RAIN QUICKLY CHANGING TO SNOW SHOWERS BEHIND
THE FRONTAL PASSAGE TUESDAY AFTERNOON. COLD NORTHWEST FLOW WILL
CONTINUE AT LEAST THE CHANCE FOR SNOW SHOWERS THROUGH TUESDAY
NIGHT. A DEEP UPPER LEVEL TROUGH WILL REMAIN OVER THE EASTERN
CONUS THROUGH THE REST OF THE WEEK KEEPING TEMPERATURES BELOW
SEASONAL AVERAGES THROUGH THE REST OF THE PERIOD.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
A SURFACE LOW WILL PUSH EAST OF THE AREA...PULLING THE FRONTAL
BOUNDARY THAT HAS BEEN DRAPED ACROSS THE AREA SOUTHWARD TONIGHT.
LOW-LEVEL MOISTURE ASSOCIATED WITH THIS SYSTEM WILL CONTINUE TO
BRING PREVAILING IFR CEILINGS AND IFR VISIBILITIES AT TIMES NORTH
OF A KZZV-KMGW LINE...WITH MVFR SOUTHWARD. AS THE FRONT SLIDES
SOUTHWARD...WINDS AT 5 TO 10KTS WILL SHIFT TO MORE NORTHERLY THIS
EVENING.
THE BIGGEST UNCERTAINTY IN THE FORECAST IS HOW LONG IFR
CEILINGS WILL LINGER. FORECAST IS OPTIMISTIC BASED OFF OF UPSTREAM
OBSERVATIONS AND LAMP GUIDANCE...INDICATING THAT CEILINGS WILL
LIFT TO MVFR OVERNIGHT. HOWEVER...AN ALTERNATIVE SCENARIO IS THAT
LOCATIONS NORTH OF KMGW/KZZV REMAIN IFR THROUGH THE OVERNIGHT.
MVFR CEILINGS WILL FINALLY LIFT TO VFR AS HIGH PRESSURE BUILDS IN
FROM THE NORTHWEST ON SUNDAY.
.OUTLOOK.../SUNDAY THROUGH THURSDAY/...
RESTRICTIONS ARE POSSIBLE ALONG WITH A WINTRY MIX OF
RAIN...SNOW...AND FREEZING RAIN EARLY MONDAY. PRECIPITATION WILL
CHANGE TO ALL RAIN ON MONDAY BEFORE A COLD FRONT USHERS COLDER AIR IN
FROM THE NORTHWEST AND ALLOWS FOR PRECIPITATION TO CHANGE OVER TO
SNOW SHOWERS MONDAY NIGHT. A NORTHWESTERLY FLOW IN THE WAKE OF THE
FRONT WILL THEN ALLOW FOR CEILINGS RESTRICTIONS WITH THE SLIGHT
CHANCE OF RAIN AND SNOW SHOWERS TUESDAY INTO THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1203 PM EDT SAT MAR 16 2013
.SYNOPSIS...
AREAS OF RAIN AND SNOW WILL CONTINUE THIS MORNING...THEN DIMINISH
THROUGH THE AFTERNOON AS A COLD FRONT SAGS ACROSS THE REGION.
STRONG LOW PRESSURE IS EXPECTED TO GENERATE MIXED PRECIPITATION ON
SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST MESOANALYSIS INDICATES STRONG LOW LEVEL FRONTOGENESIS OUT
AHEAD OF THE SURFACE LOW THAT IS TRAVERSING OHIO THIS MORNING.
THIS...COUPLED WITH ASSISTANCE FROM THE LEFT EXIT REGION OF A JET
STREAK ALOFT IS PROVIDING FOR THE BETTER SNOW RATES THAT HAVE BEEN
FOCUSED MAINLY NORTH OF I-80 THIS MORNING DESPITE MEAGER MOISTURE. WHILE
MOST OF THIS LIFT IS CONCENTRATED BELOW OPTIMAL SNOW GROWTH
LAYER...THE DYNAMICS OF THE SYSTEM SEEM TO BE WINNING OUT. STILL
WITH THE HIGH SUN ANGLE FOR MID MARCH...EXPECT THAT THE BOUNDARY
LAYER WILL EVENTUALLY WARM...MAKING IT LESS LIKELY FOR SNOW TO
STICK. WILL CONTINUE TO HIGHLIGHT ANY LOCALIZED SNOW CONCERNS VIA
SPS TODAY.
AS THE FRONT CONTINUES TO TIGHTEN OVER THE REGION...WHICH IS ALSO
IMPLIED BY THE SIGNIFICANT TEMPERATURE DIFFERENCE FROM NORTH TO
SOUTH...THINK TEMPERATURES COULD EASILY RISE INTO THE MID 50`S IN
THE SOUTH PER THE MOST RECENT HRRR GUIDANCE.
THE FRONT WILL GRADUALLY SHIFT TO THE SOUTH AND THE LOW WILL
DEPART TO THE EAST...ENDING PRECIPITATION BY THIS EVENING. HIGH
PRESSURE BUILDING SOUTHWARD FROM CANADA WILL KEEP THE FRONTAL
BOUNDARY SOUTH OF THE REGION TONIGHT AND SUNDAY.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
SUNDAY CONTS TO LK DRY FOR MOST COUNTIES AS MDLS HAVE MAINTAINED
PROGNOSIS OF SUFFICIENT SWD PROGRESS OF THE FRONTAL BNDRY. THE
EXCEPTION MAY BE FOR AREAS TO THE SOUTH OF I 68 WHERE SMALL POPS
WERE MAINTAINED DUE TO FRONT PROXIMITY. TEMPS WERE FORECAST WELL
BELOW THE AVERAGES WITH SFC HIGH PRES SETTLING OVR THE AREA...BUT
USING WARMER SREF GUIDANCE.
VARIOUS MDLS PREDICTABLY HANDLES THE APPRCH OF LOW PRES UP THE OH
VALLEY DIFFERENTLY FOR THE SUN NGT AND MONDAY PERIOD. WITH THE
DVLPMNT OF WARM ADVCTN AHEAD OF THE APPRCHG LOW...AND THE
ENTRENCHMENT OF COLD...DRY AIR VIA SFC HIGH PRES...CONFIDENCE IN A
MIXED PCPN EVENT IS RISING FOLLOWING A PD OF INITIAL SN. THAT
POTENTIAL INCLUDES FZRA AND WL MAKE MENTION IN THE HAZARDOUS WEA
OUTLOOK. THE FORECAST WAS BASED ON THE TRACK CONSTRUCTED BY THE
GFS...WHICH RMNS CLOSE TO YSTRDAS PROGNOSIS. GIVEN THAT SCENARIO...PCPN
IS EXPECTED TO CHANGE TO RAIN BY AFTN AS WARM ADVCTN DRIVES HIGH
TEMPS TWD THE CLIMATOLOGICAL NORMALS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A DEEPENING TROUGH OVER THE NORTHERN PLAINS WILL SWING A COLD
FRONT ACROSS THE REGION BY EARLY TUESDAY. WITH BETTER CONFIDENCE
IN THE TIMING OF THIS SYSTEM...CONTINUED THE LIKELY POPS THROUGH
TUESDAY MORNING WITH RAIN QUICKLY CHANGING TO SNOW SHOWERS BEHIND
THE FRONTAL PASSAGE TUESDAY AFTERNOON. COLD NORTHWEST FLOW WILL
CONTINUE AT LEAST THE CHANCE FOR SNOW SHOWERS THROUGH TUESDAY
NIGHT. A DEEP UPPER LEVEL TROUGH WILL REMAIN OVER THE EASTERN
CONUS THROUGH THE REST OF THE WEEK KEEPING TEMPERATURES BELOW
SEASONAL AVERAGES THROUGH THE REST OF THE PERIOD.
&&
.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
A STATIONARY FRONTAL BOUNDARY WILL REMAIN ACROSS THE AREA EARLY
TODAY...WITH A SURFACE LOW BRINGING IFR SNOW TO KFKL/KDUJ THROUGH
THE LATE MORNING. SOUTH OF THE BOUNDARY...MVFR/IFR VISIBILITIES AT THE
REMAINING TERMINALS WILL RETURN TO VFR BY LATE MORNING.
PRECIPITATION WILL QUICKLY COME TO AN END BY EARLY AFTERNOON AND
HIGH PRESSURE WILL BEGIN TO BUILD IN FROM THE NORTHWEST. EASTERLY
WINDS AT 5 TO 10KTS WILL BECOME NORTHWESTERLY BY EVENING. MVFR
CEILINGS WILL PREVAIL THIS AFTERNOON AND EARLY TONIGHT ACROSS MUCH
OF THE AREA BEFORE VFR RETURNS SUNDAY MORNING.
.OUTLOOK.../SUNDAY THROUGH WEDNESDAY/...
RESTRICTIONS ARE POSSIBLE SUNDAY NIGHT THROUGH TUESDAY MORNING AS A
WARM FRONT MOVES NORTH ACROSS THE REGION...FOLLOWED BY A COLD FRONT.
HIGH PRESSURE WILL THEN BUILD IN AND BRING VFR CONDITIONS FOR
TUESDAY INTO WEDNESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
1019 AM EDT SAT MAR 16 2013
.SYNOPSIS...
LOW PRESSURE WILL MOVE INTO THE MID ATLANTIC TODAY. A FRONT WILL
STALL ACROSS SOUTHERN VIRGINIA TONIGHT THROUGH MONDAY. WAVES OF
LOW PRESSURE WILL IMPACT THE AREA...BRINGING UNSETTLED CONDITIONS
DURING THIS TIME. A COLD FRONT WILL PASS THROUGH THE AREA MONDAY
NIGHT. HIGH PRESSURE IS EXPECTED TO RETURN TO THE AREA DURING THE
MIDDLE PORTION OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW PRESSURE WAS LOCATED NEAR THE OHIO/INDIANA BORDER AT 13Z.
FRONTAL BOUNDARY EXTENDED EAST OF THE LOW THROUGH NORTHERN WEST
VIRGINIA AND INTO FAR NORTHERN VIRGINIA/CENTRAL MARYLAND.
ONE INITIAL WAVE HAS LED TO SOME LIGHT PRECIP FROM CENTRAL
VIRGINIA INTO SOUTHERN MARYLAND. THERE/S ALSO LIGHT PRECIP OVER
NORTHEAST MARYLAND...BUT MUCH OF THE REST OF THE CWA HAS BEEN
SPARED FROM PRECIP UP TO THIS POINT.
TREND OF THE MODELS INCLUDING THE RUC AND NAM IS TO DELAY THE
BRUNT OF THE PRECIP BY A FEW HOURS...SO THE REST OF THE MORNING
WILL LIKELY BE DRY. BUT AS LOW PRESSURE MOVES EAST INTO THE MID-
ATLANTIC...RIDING ALONG THE FRONT POSITIONED OVER CENTRAL
VIRGINIA THIS AFTERNOON...MORE RAIN WILL MOVE INTO/DEVELOP OVER
THE CWA. THEREFORE...WHILE POPS HAVE BEEN REDUCED FOR THE NEXT FEW
HOURS...THEY RAMP BACK UP TO LIKELY/CATEGORICAL THIS AFTERNOON.
P-TYPE SHOULD BE ALL RAIN...AS CHILLY AIR FOR SNOW/WINTRY PRECIP
HAS BEEN OBSERVED IN PENNSYLVANIA JUST NORTH OF THE MASON DIXON
LINE AND IS LIKELY TO REMAIN THERE TODAY.
HAVE LEFT THUNDER OUT OF THE FORECAST AS MUCH OF THE CWA WILL BE
ON THE COOL SIDE OF THE BOUNDARY. EXCEPTION MAY BE TOWARD THE
EXTREME SOUTHWEST CWA...BUT INSTABILITY IS FORECAST TO BE WEAK AND
LIKELY NOT SUPPORTIVE OF THUNDER.
TWEAKED MAXIMA BASED ON LATEST BIAS CORRECTED TEMPERATURE
GRIDS...KEEPING THE LOWER TO MID 40S ALONG THE MASON DIXON LINE
AND LOWER 60S SOUTHWARD TOWARD NELSON COUNTY VIRGINIA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
PRECIP SHUTS OFF PRETTY QUICKLY FROM NW TO SE BEHIND THE
LOW. MAY HAVE SOME VERY LIGHT SNOW ACCUM /BARELY A DUSTING/ OVER
N-CNTRL MD /ABOVE 500 FT OR SO/ THIS EVENING BEFORE ENDING. SOME
CLEARING OVERNIGHT AS COOL AIR SPILLS IN FROM THE NORTH. MIN TEMPS
AROUND 30F NRN THIRD WITH LOW TO MID 30S SRN 2/3 PER MAV/MET/SREF
BLEND.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
HEMISPHERIC SHOWS THE CIRCUMPOLAR VORTEX MAINTAINING OVR CANADA
W/ A GNRL ZNL UPR LVL PATTERN...SO NO LARGE TEMP SWINGS XPCTD IN
THE COMING WK.
BUT DURG THE 1ST PART OF THE XTND THE SKIES WL HV PLENTY OF CLDS
COURTESY OF THE BNDRY WHICH WL MOVE THRU THE RGN TDA AND THEN
BECOME STATIONARY W/ BOTH A W-E UPR LVL WIND FIELD AND A SFC
HIGH...CURRENTLY N OF WINNEPEG...ON SUN THAT WL MOVE OVR NY
STATE...WHICH IN TURN WL HOLD THE BNDRY ACROSS SRN VA. BEST CHC OF
PCPN SUN WOULD BE IN THE CENTRAL SHEN VLLY. HIGHS IN M40S E OF THE
MTNS...30 IN THE HIGHLANDS.
SUN NGT THE FCST BECOMES MORE COMPLICATED AS HIGH PRES MOVES OVR
NEW ENGLAND. ALL MDLS INDICATE A CAD PRES PATTERN WL SET UP ALONG
THE E SIDE OF THE APLCHNS...AT SAME TIME LOW PRES TRACKS INTO KY
W/ A WRM FNT ACROSS SRN VA. THE LOW WL TRACK N DURG MON...BUT AHD
OF IT COULD BE A PD OF WINTRY WX. ALTHO THE GRIDS INDICATE R/S
SUSPECT THERE MAY ALSO BE SLEET IN THE MIX. ATTM DO NOT HV A GOOD
FEEL ON IF ANY ACCUMS WOULD BE PSBL..BUT W OF THE METROS COULD SEE
SOMETHING. WORSE CASE SCENARIO COULD BE THE "1 INCH DURG MON MRNG
COMMUTE" ADVSRY ON THE WRN SIDE OF THE CITIES...BUT ALSO PERHAPS
JUST A NON-ACCUMULATING SLUSH - IT IS MID MAR.
DAYS OUT IT`S ALWAYS HARD TO PREDICT HOW LONG A CAD WEDGE WL BE
ABLE TO HANG ON...ALTHO CAD DOES OCCUR HERE AT ALL TIMES OF THE
YR. FOR NOW THE ECM/GFS SOLN WL SUFFICE WHICH SHOWS THE HIGH MOVG
OFF THE ME CST MON EVE WHICH SHOULD ALLOW THE COLD WEDGE TO
ERODE...BUT MON SHOULD BE A CHILLY/WET DAY W/ HIGHS ONLY IN THE
L40S E OF THE MTNS.
MON/MON NGT WL SEE LTL IN THE WAY OF TEMP VARIATION. THE WV OF LOW
PRES THAT FORMS ALONG THE STATIONARY BNDRY LOOKS TO FINALLY BE
KICKED OUT MON NGT AS HIGH PRES BEGINS TO WORK BACK ONTO THE E
CST. THIS WL LKLY SPAWN ANOTHER PD OF RAIN...XCPT MIXING W/ SNOW
AT HIGHER ELEVS. LOW TEMPS IN THE L40S E OF THE MTNS...30S W.
FINALLY THE SUN SHOULD REAPPEAR TUE AS HIGH PRES BUILDS BACK INTO
THE AREA: A BRZY DAY W/ HIGH TEMPS RANGING FM THE U30S IN THE
HIGHLANDS TO A60 FM I-95 AND E.
HIGH PRES OVR THE MID ATLC MUCH OF THE RMDR OF THE WK...BUT W/ AN
UPR LVL VORTEX OVR NEW ENGLAND THIS WL KEEP TEMPS ON THE COOL
SIDE: HIGHS IN THE 40S WED-FRI E OF THE MTNS.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
RADAR TRENDS/MODELS SUGGEST HUBS WILL REMAIN DRY FOR THE NEXT FEW
HOURS...BUT AS LOW PRESSURE PASSES TO THE SOUTH THIS AFTERNOON WE
STILL EXPECT SOME LIGHT RAIN TO MOVE THROUGH LATER THIS AFTERNOON.
IN RAIN...CONDITIONS LIKELY DETERIORATE TO MVFR. CONFIDENCE HAS
LESSENED ON IFR...BUT WITH EASTERLY FLOW THERE MAY BE A PERIOD
LATE THIS AFTERNOON/EVENING FOR IFR BEFORE PRECIPITATION ENDS.
VFR CONDITIONS ARE EXPECTED SUNDAY MORNING...BUT CIGS/VSBYS WILL
DETERIORATE SUNDAY AFTERNOON AS RAIN OVERSPREADS THE AREA. RAIN
WILL MIX WITH AND MAYBE EVEN CHANGE TO SNOW SUNDAY NIGHT INTO
MONDAY BEFORE TURNING BACK TO RAIN LATER MONDAY. IFR CIGS/VSBYS
ARE EXPECTED DURING THIS TIME.
IFR CONDITIONS WILL CONTINUE MONDAY NIGHT BEFORE A COLD FNT MOVES
THROUGH TUESDAY. GUSTY WESTERLY WINDS ARE EXPECTED BEHIND THE
FRONT WITH VFR CONDITIONS.
&&
.MARINE...
FRONTAL BOUNDARY SLIPS SOUTH OF THE NORTHERN BAY TODAY...STALLING
OUT OVER THE SOUTHERN BAY THIS EVENING. EXPECT WINDS MAINLY OUT OF
THE EAST DURING THIS PERIOD...10 KT OR LESS WITH WEAK GRADIENT.
AFTR A CLDY/WET SUN/MON THE BEST CHC FOR SCA CONDS IN THE XTND WL
BE TUE AS HIGH PRES RETURNS TO THE WATERS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
BPP/BAJ/WOODY!
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
100 AM EDT SAT MAR 16 2013
.AVIATION...
//DISCUSSION...
PRECIPITATION HAS TURNED TO ALL SNOW ACROSS THE TAF SITES AS COLDER
IN THE LOW LEVELS FILTERS IN. PREDOMINATELY MVFR CONDITIONS THIS
MORNING...BUT MODERATE TO BRIEFLY HEAVY SNOW EXPECTED TO IMPACT THE
MAJORITY OF THE TAFS WITH IFR/LIFR CONDITIONS...LEADING TO SOLID 2
TO 3 INCHES OF SNOW ACCUMULATION TOWARD SUNRISE SATURDAY. THE
EXCEPTION BEING MBS WHICH IS EXPECTED TO BE ON THE NORTHERN FRINGE
OF THE SNOW ACTIVITY.
SNOW WILL TAPER TO FLURRIES QUICKLY SATURDAY MORNING...WITH
LEFTOVER MVFR CEILINGS...LIFTING TO LOW VFR SATURDAY AFTERNOON.
STILL...WITH RESIDUAL NORTHERLY FLOW IMPACT FROM LAKE HURON...WILL
HOLD ONTO LOW VFR/HIGH MVFR CEILINGS SATURDAY EVENING WITH LIGHT
WINDS.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET TODAY...DECREASING
CONFIDENCE TONIGHT.
* HIGH CONFIDENCE SNOW WILL BE THE PRECIPITATION TYPE.
&&
.PREV DISCUSSION...ISSUED 1021 PM EDT FRI MAR 15 2013
UPDATE...
THE EVENING UPDATE WILL UPGRADE TO AN ADVISORY FOR THE M-59 TO
I-69 CORRIDOR THROUGH 8 AM SATURDAY MORNING, AND EXTEND 3-4 INCH
SNOWFALL TOTALS EASTWARD THROUGH THE MOUNT CLEMENS TO PORT HURON
CORRIDOR WITH THE NEXT SYSTEM. EXPECT THE ENTIRE I-69 TO M-59
REGION TO BE SOLIDLY IN THE 3-4 INCH RANGE IN A 6 HOUR PERIOD FROM
ABOUT 2 AM TO 8 AM, WITH AMOUNTS TAPERING OFF TO THE NORTH AND TO
THE SOUTH. THE SYSTEM WILL BE CAPABLE OF AT LEAST ENTRY LEVEL
ADVISORY CRITERIA GIVEN THE STRONG DYNAMIC AND LOW STABILITY
ENVIRONMENT ASSOCIATED WITH THE UPSTREAM WAVE. SNOW RATIO REMAINS
THE PRIMARY LIMITING FACTOR AT ONSET BUT IS EXPECTED TO RECOVER
INTO THE 10-12:1 RANGE IN THE ADVISORY AREA FOR THE PEAK OF THE
EVENT.
EXPECT A SHORT RESPITE IN PRECIP ACTION DURING THE LATE EVENING
THROUGH ABOUT MIDNIGHT AS THE LEAD SHORT WAVE SHEARING TO OUR
SOUTH EXITS EAST. THE NEXT SYSTEM SHOWS A NOTABLE TRAILING
SUBSIDENCE REGION OVER MINNESOTA IN WV IMAGERY INDICATIVE OF
SYSTEM STRENGTH ON TRACK WITH MODEL DEPICTIONS. RADAR COMPOSITES
AND SURFACE REPORTS SHOW A CONSIDERABLE AREA OF SNOW OVER CENTRAL
MINNESOTA INTO CENTRAL WISCONSIN WITH GENEROUS COVERAGE OF HALF
MILE VISIBILITY. MODEL DEPICTIONS OF SURFACE CYCLOGENESIS OVER THE
OHIO VALLEY INDICATE THE SYSTEM FORCING WILL MAINTAIN OR EVEN
INCREASE ITS STRENGTH OVER LOWER MICHIGAN DURING THE OVERNIGHT
HOURS WHICH WILL SUPPORT A WELL-ORGANIZED FGEN BAND IN THE
850-700 MB LAYER OVER CENTRAL SECTIONS OF SE MICHIGAN. MODEL
SOUNDINGS AND CROSS SECTIONS FROM THE LATEST RAP AND INCOMING NAM
SUPPORT THE VERY LOW STATIC STABILITY ENVIRONMENT WITH SOME
SHALLOW LAYERS OF INSTABILITY ALOFT ON THE WARM SIDE OF THE
FRONTAL SLOPE HELPING TO MAXIMIZE LIFT IN THE BAND. COMBINE THAT
WITH 3-4 G/KG SPECIFIC HUMIDITY AND THE RESULT WILL LIKELY BE AN
ADVISORY WORTHY BURST OF SNOW ENDING QUICKLY SHORTLY AFTER
SUNRISE.
PREV DISCUSSION...ISSUED 408 PM EDT FRI MAR 15 2013
SHORT TERM...THIS EVENING AND TONIGHT
REGIONAL SATELLITE AND RADAR IMAGERY SHOW TWO PREVIOUSLY DISCUSSED
FOCI OF INTEREST OVER (1) SOUTHERN WI/NORTHERN IL AND (2) NORTH
DAKOTA THIS AFTERNOON. THE FIRST IS AN ONGOING COMPACT REGION OF
RAIN AND SNOW BEING FUELED BY STRONG RIGHT ENTRANCE REGION DYNAMICS
MIGRATING TOWARD THE WESTERN GREAT LAKES. ANALYSIS OF THE 12Z
GUIDANCE INDICATES THE BAROCLINIC ZONE DRAPED ACROSS THE AREA WILL
BE THE MOST ACTIVE BETWEEN 925-850MB THROUGH TONIGHT, AND THIS HAS
HELD TRUE FOR BOTH WAVES OF INTEREST SO FAR TODAY. THIS ACTIVITY
WILL SPREAD INTO THE CWA AS UPPER SUPPORT MIGRATES EAST. HOWEVER, A
SLOWER PROGRESSION OF THE TRAILING WAVE HAS PREVENTED ANYTHING IN
THE WAY OF JET COUPLING WHICH DECREASES EXPECTATIONS FOR THIS
INITIAL WAVE. IN ADDITION, THE SURFACE COLD FRONT NOTED IN THE OBS
AND ON THE EXETER, ONTARIO RADAR CONTINUES TO DIVE SOUTH THIS
AFTERNOON. THE HIGHEST RESOLUTION GUIDANCE AVAILABLE, INCLUDING THE
BROADER SCALE NAM12, INDICATE THAT THIS HIGHER THETA-E AIRMASS WILL
AGGRESSIVELY ACCELERATE ONSHORE AND CONTINUE DOWNRIVER THROUGH THE
EVENING. COLD AIR AND, MOST NOTABLY, MUCH LOWER DEWPOINTS ARE
THEREFORE FORECAST TO SPREAD FROM NORTHEAST TO SOUTHWEST ACROSS THE
CWA THROUGH LATE EVENING. THE MULTITUDE OF EFFECTS THAT THIS WILL
HAVE ON THE EVOLUTION OF THE FIRST WAVE WILL BE TO LIMIT THE
NORTHWARD EXTENT OF SNOW WHERE FORCING IS WEAKEST AS DRIER AIR
INFILTRATES THE BOUNDARY LAYER, ENHANCE LOW-LEVEL CONVERGENCE ALONG
ITS LEAD EDGE RESULTING IN POTENTIAL FOR A BURST OF HIGHER SNOWFALL
RATES AS IT BECOMES JUXTAPOSED WITH THE INCREASINGLY ACTIVE H85
FRONT, AND FINALLY THERE WILL BE INCREASED POTENTIAL FOR BOUNDARY
LAYER WET-BULBING WHICH YIELDS HIGHER CONFIDENCE IN ALL SNOW PTYPE.
SPECIFICALLY, PTYPE SHOULD BE ALL SNOW NORTH OF I-94 BY 00Z AND
SOUTH OF I-94 BY 03Z. HOWEVER, AS JET SUPPORT RAPIDLY WANES OVER THE
NEXT 6 HOURS OR SO, IT IS HARD TO EXPECT ANY BETTER THAN ONE INCH
SOUTH OF I-69 WITH PERHAPS 0.5" SOUTH OF I-96 ONCE PTYPE BECOMES ALL
SNOW.
AS THE NIGHT WEARS ON, DYNAMIC FORCING WILL INCREASE DRAMATICALLY AS
A MUCH MORE POTENT WAVE DIVES OUT OF THE NORTHWEST FLOW ALOFT. THIS
WILL PROMPT THE DEVELOPMENT OF A 100 KT JET STREAK TO OUR WEST AND
SOUTH AFTER 03Z. INITIALLY, FAST FORWARD MOTION AND STRENGTHENING
LEFT EXIT DYNAMICS WILL PROMOTE INCREASING SYSTEM RELATIVE
ISENTROPIC ASCENT DURING THE OVERNIGHT HOURS, RESULTING IN AN
INCREASE IN PRECIP COVERAGE FROM SOUTHWEST TO NORTHEAST FROM 03Z-09Z
AS THE NW-SE ORIENTED JET STREAK PUSHES EAST. STRENGTHENING
925-850MB LOW/MID LEVEL FGEN DURING THE SAME TIME WINDOW WILL BECOME
FOCUSED SOUTH OF THE INTERSTATE 69 CORRIDOR FOR THE VAST MAJORITY OF
THE PASSAGE OF THE SECOND WAVE. MID-LEVEL DEFORMATION WILL ALSO BE
COLLOCATED WITHIN THE SAME CORRIDOR AS THE SURFACE LOW RIPPLES BY TO
OUR SOUTH A FEW HOURS PRIOR TO SUNRISE.
UPSTREAM TRENDS AND 12Z MODEL CROSS-SECTIONS OFFER SOME SUPPORT FOR
UPRIGHT CONVECTION, WHICH SUGGESTS THE POTENTIAL FOR POCKETS OF
HIGHER AMOUNTS. THIS POTENTIAL FOR STRONG VERTICAL MOTION TO OCCUR
ON AN APPRECIABLE SPATIAL SCALE CASTS SOME UNCERTAINTY ON THE
NORTHWARD EXTENT OF MOISTURE TRANSPORT ALONG THE FRONTAL SLOPE.
GIVEN THE APPARENT LIKELIHOOD FOR CONVECTION TO PLAY A SOMEWHAT
PROMINENT ROLE, THE MORE NORTHERLY NAM12 SOLUTION SEEMS LESS
REASONABLE WHEN COMPARED TO THE MORE SOUTHERLY 12Z NMM, GEM, AND
ECMWF WHILE THE GFS REMAINS AN UNREASONABLE OUTLIER ON THE SOUTHERN
END OF THE SPECTRUM. THE FORECAST IS THEREFORE STRONGLY BASED UPON A
BLEND OF THE AFOREMENTIONED FAVORED GUIDANCE. A RATHER NARROW
DENDRITE GROWTH LAYER THAT WILL BE ONLY MARGINALLY SUPERSATURATED
OUTSIDE OF CONVECTION AND ONLY BRIEFLY COLLOCATED WITHIN THE LAYER OF
MAX ASCENT WILL YIELD UNIMPRESSIVE SNOWFALL RATIOS AROUND 10:1. BY
12Z SATURDAY MORNING, EXPECTING ALONG THE LINES OF 1-3" ALONG AND
WEST OF THE I-75 CORRIDOR, BEST POTENTIAL FOR 2-3" BETWEEN I-96 AND
I-69, AND LESS THAN ONE INCH FOR THE NORTHEAST THUMB AND SOUTHERNMOST
TIER OF COUNTIES.
LONG TERM...SATURDAY THROUGH NEXT FRIDAY
VERY WEAK SYSTEM RELATIVE ISENTROPIC ASCENT WILL PERSIST AS THE WEAK
THERMAL WAVE NEEDS TO WORK THROUGH THE CWA. THIS SHOULD PERPETUATE
THE BACK EDGE LIGHT SNOW BETWEEN 12-15Z ACROSS THE FAR EASTERN CWA
BEFORE EXITING STAGE RIGHT. SYSTEM RELATIVE FLOW ON THE 280K SURFACE
THEN INDICATES THAT SUBSIDENCE WILL ACTIVATE RATHER ABRUPTLY AFTER
15Z...DRYING THINGS OUT. DESPITE ACTIVE SUBSIDENCE PER EVOLUTION OF
BUFR SOUNDINGS AND ISENTROPIC ANALYSIS...TRAJECTORIES TOMORROW WILL
BE FROM ONTARIO IMMEDIATELY NORTH AND EAST OF GEORGIAN BAY...WHERE
THERE IS A VERY HEALTHY STRATUS-STRATOCUMULUS DECK (2000-4000FT)
THIS AFTERNOON. WILL KEEP CLOUDS IN THROUGHOUT SATURDAY AFTERNOON AS
THIS PREEXISTING SATURATION/CLOUD SHOULD BE A SIGN THAT CLOUDS WILL
PERSIST OVER SOUTHEASTERN MICHIGAN TOMORROW SUB INVERSION. WITH FLOW
OFF OF THE LAKE AND A CLOUD DECK IN PLACE...PREFERRED RAW GUIDANCE
TO ANY BIAS CORRECTED OFFERINGS.
A VERY SHARP WAVE IS FORECASTED TO TUMBLE ACROSS THE FAR NORTHERN
GREAT LAKES SATURDAY NIGHT. THIS FEATURE IS THEN SHOWN TO DRIVE A
BACKDOOR TYPE FRONT SOUTHWARD OFF OF LAKE HURON AND THROUGH LOWER
MICHIGAN. THE NWP CONSENSUS THE PAST COUPLE OF DAYS HAS LARGELY BEEN
DRY. AGAIN...SYSTEM RELATIVE FLOW IS DOWN THE ISENTROPES THROUGH
SATURDAY EVENING...BECOMING REINFORCED AFTER THE PASSAGE OF THE
QUASI BACKDOOR FRONTAL RESPONSE.
THE DOMINANT POLAR SURFACE ANTICYCLONE IS THEN SHOWN TO DRIVE ANY
LOWER TROPOSPHERIC FRONTAL RESPONSE DOWN INTO THE OHIO RIVER
REGION BY SUNDAY EVENING. THE OVERALL HIGH MAGNITUDE OF THIS
SURFACE HIGH AND MIDLEVEL RIDGE COUPLET SHOULD THEN BE A BLOCKING
FEATURE FOR THE STRONG JET/SHORTWAVE ENERGY THAT IS EXPECTED TO
SLIDE EAST SOUTHEASTWARD TOWARDS THE GREAT LAKES SUNDAY NIGHT.
THIS JET IS SHOWN TO GO INTO THE WESTERN RIDGE FACE. THE OVERALL
GOVERNOR ON HOW THIS SYSTEM THIS WEEKEND WILL EVOLVE IS THE
INTERACTION BETWEEN THIS NORTHERN UPPER LEVEL PV ANOMALY WITH THE
SOUTHERN MIDLEVEL/LATENT HEAT PV ANOMALY SHOWN TO LIFT NORTHWARD
OUT OF THE TENNESSEE RIVER VALLEY. OVERALL...MODEL CONSENSUS
ECMWF/GFS/UKMET DEPICTS ENOUGH SEPARATION BETWEEN THE TWO TO
CAUSE THE SOUTHERN PRECIPITATION TO LIFT AND DEFLECT
EASTWARD...MERELY BRUSHING THE FAR SOUTH. MEANWHILE...THE GEM IS
FAR AND AWAY THE MOST AGGRESSIVE...PHASING THE ENERGY...AND CARRYING
MOISTURE AND SIGNIFICANT PRECIPITATION NORTHWARD. WITH THE IDEA
THAT THE STRONG RIDGING IN ADVANCE OF THE NORTHERN WAVE WILL SET
UP A BLOCK AND THE PLACEMENT OF THE SOUTHERN MIDLEVEL PV ANOMALY
ON THE FRINGE EDGE OF THE SURFACE HIGH/RIDGE...HAVE SIGNIFICANTLY
LOWERED PRECIPITATION/QPF AMOUNTS FOR SUNDAY NIGHT AND MONDAY
MORNING. WITH THE CONDITIONAL IDEA IN MIND...LEFT INHERITED
PTYPES INTACT.
MARINE...
SMALL CRAFT ADVISORIES REMAIN IN EFFECT AS PERSISTENT MODERATE
NORTHEAST FLOW IS EXPECTED TO BUILD WAVES INTO THE 3 TO 6 FOOT RANGE
FOR THE NEARSHORE ZONES OF LAKE HURON. WINDS WILL BECOME LIGHT AND
VARIABLE FOR MOST AREAS DURING THE SECOND HALF OF THE
WEEKEND...EXCEPT OVER THE NORTHERN HALF OF LAKE HURON...WHERE A BACK
DOOR COLD FRONT WILL SUPPORT NORTHWEST WINDS IN EXCESS OF 20 KNOTS.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY...MIZ053-MIZ060-MIZ061-MIZ062-MIZ063-MIZ068-
MIZ069-MIZ070...UNTIL 10 AM SATURDAY.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING OUTER SAGINAW BAY...UNTIL 8 PM SATURDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....SF
UPDATE.......BT
SHORT TERM...JVC
LONG TERM....CB
MARINE.......JVC
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
915 AM MDT SAT MAR 16 2013
.SHORT TERM...VALID FOR TDY AND SUN...
FORECAST PROBLEM THIS MORNING REVOLVES AROUND TEMPERATURES TODAY.
LOW LEVEL EASTERLY FLOW BACKED UP NEAR THE FOOTHILLS OVERNIGHT
SPREADING LOW CLOUD DECKS AND CHILLY AIR ACROSS MUCH OF THE
FORECAST AREA...THOUGH IT DIDNT QUITE MAKE IT INTO LIVINGSTON.
QUESTION IS HOW LONG IT STAYS AROUND IN THE WEST AS IT WILL HAVE A
SIGNIFICANT IMPACT ON TEMPERATURES. MODELS ARE NOT IN GOOD
AGREEMENT WITH 06Z GFS KEEPING EASTERLY FLOW IN BILLINGS THROUGH
THE DAY...WHILE RAP AND NAM HAVE WESTERLY FLOW PUSH THROUGH
BILLINGS BY EARLY AFTERNOON. HRR ACTUALLY HAS WESTERLY FLOW TAKING
OVER BY 9 AM...AND ALSO PUSHING RATHER FAR EAST. THIS IS OBVIOUSLY
TO EARLY AND I SUSPECT TO FAR EAST. WEAK PRESSURE FALLS OCCURRING
ALONG THE FRONT RANGE LAST COUPLE OF HOURS SUPPORT AT LEAST SOME
RETREAT OF THE CHILLY AIR LATER TODAY...BUT I THINK IT WILL BE
DELAYED AND NOT REACH THE FAR EASTERN ZONES. THUS WILL DROP
TEMPERATURES IN THE EAST AND CENTRAL ZONES. BILLINGS MAY BE RIGHT
ON THE BORDER OF THE COOLER AIR...EVENTUALLY TURNING WESTERLY BUT
MIGHT TOO FAR INTO THE AFTERNOON TO PREVENT A DECENT WARM UP.
IN ADDITION...SUBTLE ENERGY IN WEST TO NORTHWEST FLOW ALOFT AIDED
BY OVERRUNNING WILL PRODUCE SCATTERED RAIN OR SNOW SHOWERS. HAVE
INCREASED POPS ACROSS NORTHERN AND EASTERN ZONES THIS MORNING
BASED ON CURRENT RADAR ECHOES. BT
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
THE EXTENDED FORECAST CONTINUES ON TRACK THIS MORNING...WITH
ONLY MINOR CHANGES TO THE FORECAST. TO QUICKLY BREAKDOWN THE
EXTENDED PERIOD: MONDAY THROUGH WEDNESDAY WILL SEE A SLOW WARMING
TREND BACK TO THE 50S BY WEDNESDAY...BEFORE ANOTHER PACIFIC
WEATHER SYSTEM APPROACHES WEDNESDAY NIGHT INTO THURSDAY BRINGING
COLDER TEMPERATURES AND A CHANCE OF ACCUMULATING SNOW FALL FOR
MUCH OF THE AREA.
NORTHWESTERLY FLOW WILL DEVELOP ALOFT ON MONDAY BEHIND THE EXITING
SUNDAY WEATHER SYSTEM. WITH THE JET STREAM REMAINING OVER THE
FORECAST AREA...EXPECT TO SEE A TEMPERATURE GRADIENT ACROSS THE
FORECAST AREA...WITH LOCATIONS ACROSS EASTERN MONTANA REMAINING
COOL ON MONDAY. SOME MOISTURE IN THE NORTHWESTERLY FLOW ALONG WITH
A STALLED SURFACE FRONT ACROSS THE AREA...WILL LIKELY RESULT IN
SOME SCATTERED SNOW SHOWERS ESPECIALLY OVER THE HIGHER TERRAIN.
FOR TUESDAY...RIDGING WILL CONTINUE TO BUILD IN ALOFT...SHIFTING
THE SURFACE FRONT EASTWARD AND ALLOWING FOR GRADUAL WARMING OF
TEMPERATURES AND A RETURN TO SOUTHWESTERLY FLOW ACROSS MUCH OF
THE FORECAST AREA. CONDITIONS WILL ALSO DRY OUT...SO THE PREVIOUS
SHIFT CHANGES OF REDUCING POPS FOR TUESDAY LOOK ON TRACK.
FOR WEDNESDAY...THE RIDGE AXIS WILL SHIFT ACROSS THE FORECAST
AREA...WITH SOUTHWESTERLY FLOW ALOFT AHEAD OF THE NEXT PACIFIC
TROUGH. WE WILL SEE OUR WARMEST TEMPERATURES ON WEDNESDAY...WITH
HIGHS RETURNING BACK INTO THE 50S THANKS TO INCREASED
SOUTHWESTERLY DOWNSLOPE FLOW. MIDDLE AND HIGH CLOUDS WILL START TO
INCREASE ESPECIALLY BY WEDNESDAY AFTERNOON AHEAD OF THE PACIFIC
TROUGH...WHICH WILL INHIBIT DAYTIME HEATING SOME.
WEDNESDAY NIGHT INTO THURSDAY WILL LIKELY SEE A COLD FRONTAL
PASSAGE AS THE NEXT PACIFIC TROUGH STARTS TO TRACK ACROSS THE
FORECAST AREA. MODELS REMAIN IN FAIRLY GOOD AGREEMENT WITH THIS
SYSTEM...GIVEN THE FORECAST TIME RANGE...HOWEVER DETAILS REMAIN
UNCERTAIN. SO FAR THE KNOWN QUANTITIES WITH THIS SYSTEM ARE THE
RETURN TO COLDER TEMPERATURES...UNSTABLE LAPSE RATES...AND A
POSSIBLE GULF OF MEXICO MOISTURE TAP. THESE FACTORS ARE CONCERNING
FOR THE POTENTIAL TO PRODUCE HEAVY PRECIPITATION AND THUS
WIDESPREAD ACCUMULATING SNOW FALL. FOR NOW...THE EVOLUTION OF
THIS SYSTEM WILL REMAIN ONE TO KEEP A WATCHFUL ON EYE.
CHURCH
&&
.AVIATION...
EXPECT MOSTLY CLOUDY SKIES THIS MORNING WITH LOW CEILINGS AND
MVFR TO IFR CONDITIONS FROM KBIL WESTWARD. SKIES ARE EXPECTED TO
BECOME PARTLY SUNNY WITH VFR CONDITIONS PREVAILING BY EARLY
AFTERNOON. HOWEVER...AREAS FURTHER EAST TOWARD KMLS AND KBHK CAN
EXPECT THESE LOW CEILINGS AND VISIBILITIES THROUGHOUT THE DAY. IN
ADDITION...THERE WILL ALSO BE A CHANCE FOR RAIN AND SNOW SHOWERS
THIS AFTERNOON. MOUNTAIN OBSCURATIONS WILL BE LIKELY AT TIMES
THROUGHOUT THE DAY. HOOLEY
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 049 039/044 021/043 026/049 028/052 030/042 023/039
2/W 48/W 42/W 11/B 12/W 45/W 43/J
LVM 053 040/041 019/040 025/047 027/049 030/044 022/042
3/W 67/W 42/W 22/W 23/W 54/W 33/J
HDN 049 033/048 020/043 025/049 027/052 028/044 022/038
2/W 39/W 42/W 21/B 12/W 45/W 53/J
MLS 036 030/040 013/039 023/046 025/046 026/039 021/037
4/W 49/J 51/B 11/B 11/B 35/J 53/J
4BQ 043 030/046 016/036 022/046 023/048 025/039 021/036
3/W 29/W 62/W 21/B 11/B 35/J 53/J
BHK 031 025/039 010/030 018/041 020/037 022/033 018/033
3/W 39/J 61/N 11/B 11/B 35/J 53/J
SHR 047 031/043 017/035 019/043 022/049 026/040 020/034
2/W 28/W 62/J 21/B 11/B 35/J 42/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WATCH IN EFFECT FROM SUNDAY MORNING THROUGH LATE
SUNDAY NIGHT FOR ZONES 31>33-36-37.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION...UPDATED
NWS OMAHA/VALLEY NE
945 PM CDT SUN MAR 17 2013
.UPDATE...
DIFFICULT FORECAST AT BEST OVERNIGHT AS FAR AS SNOW AMOUNTS GO.
AREA OF SHOWERS TO THE WEST HAD PRODUCED SOME SNOW EARLIER AND
WAS LIKELY A MIX AT SOME SPOTS. TEMPS HAVE BEEN FAIRLY STEADY
IN THE MID 30S TO AROUND 40...WHICH HAS LIMITED ACCUMULATIONS SO
FAR. AS THE NIGHT GOES ON...MODELS SHOW THE ATMOSPHERE COOLING AND
SO SOME SNOW IS LIKELY. LATEST RADAR IMAGES ALSO SHOW AREAS OF
HIGHER REFLECTIVITY WHICH ARE LIKELY A RAIN/SLEET OR SNOW MIX.
BUMPED POPS UP AND SNOW AMOUNTS UP EARLIER...BUT 00Z NAM SUGGESTS
AMOUNTS WOULD BE LESS THAN HALF AN INCH AT ALL LOCATIONS.
A WIND ADVISORY MAY BE NEEDED FOR AT LEAST PARTS OF THE AREA
MONDAY.
MILLER
&&
.PREV DISCUSSION... /ISSUED 621 PM CDT SUN MAR 17 2013/
AVIATION...
00Z TAFS FOR KOMA...KLNK...KOFK.
MAIN AVIATION CONCERN IS STILL THE TIMING OF PCPN/LOW CEILINGS
AND RESTRICTIONS TO VISIBILITY DEVELOPING THIS EVENING AND THEN
CONTINUING INTO THE OVERNIGHT HOURS. BAND OF PCPN IS EVIDENT ON
RADAR LOOP AND WILL BE MOVING EASTWARD. EXPECT AT LEAST TEMPO
IFR CONDITIONS WITH HEAVIEST PCPN. CONDITIONS SHOULD BECOME VFR
IN THE 09Z-12Z TIMEFRAME AT KOFK...10Z-13Z AT KLNK AND 12Z-15Z
AT KOMA. STRONG NORTHWEST WINDS WILL ALSO OVERSPREAD THE AREA
WITH GUSTS OVER 30 KNOTS. RAP MODEL IS QUITE GENEROUS WITH PCPN
AMOUNTS SO WILL HAVE TO MONITOR THAT THROUGH THE EVENING. WILL
AMEND AS NEEDED.
MILLER
PREV DISCUSSION... /ISSUED 305 PM CDT SUN MAR 17 2013/
SHORT TERM...TONIGHT THROUGH WEDNESDAY.
TEMPERATURES WILL BE THE PRIMARY FORECAST CONCERN IN THE SHORT
TERM WITH SNOWFALL POTENTIAL TONIGHT ALSO A FOCUS.
SURFACE LOW PRESSURE OVER WESTERN SOUTH DAKOTA AT 19Z WILL TRACK
ACROSS THE DAKOTAS TONIGHT REACHING NORTHERN MINNESOTA BY MONDAY
MORNING. A SURFACE TROUGH STRETCHING SOUTH FROM THE LOW WILL
MOVE ACROSS NEBRASKA OVERNIGHT AND ACT AS A FOCUS FOR SHOWERS
AS THE SYSTEM MOVES EAST. SOME POTENTIAL FOR SNOW TONIGHT BUT
SURFACE TEMPERATURES AND SPEED OF THE SYSTEM WILL BE LIMITING
FACTORS FOR MUCH ACCUMULATION. BEST LOCATION APPEARS TO BE WEST
CENTRAL IOWA WHERE BETTER THERMAL PROFILE IS EXPECTED. SOME
SNOW COVER ALSO REMAINS IN THIS AREA HELPING TO MAINTAIN COLDER
SURFACE TEMPERATURES. NONETHELESS...ONLY EXPECT SNOWFALL UP TO AN
INCH AFTER MIDNIGHT DUE TO THE SPEED OF THE SYSTEM.
COLD FRONT IS EXPECTED TO BE NEAR THE NEBRASKA SOUTH DAKOTA
BORDER BY MORNING AND WILL SWEEP ACROSS THE AREA BY AFTERNOON.
GUSTY NORTHWEST WINDS FOLLOW BEHIND THE FRONT AND MAY APPROACH
ADVISORY LEVELS ACROSS NORTHEAST NEBRASKA BY LATE MORNING. WILL
LET MIDNIGHT CREW DECIDE IF HEADLINES ARE NEEDED. AREA THEN
REMAINS UNDER COLD NORTHWEST FLOW THROUGH WEDNESDAY WITH PERIODS
OF CLOUDS BUT NO PRECIP AS WEAK WAVES DROP DOWN IN THE FLOW.
FOBERT
LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY.
COLD...CLOUDY...WITH A CHANCE OF LIGHT SNOW IS THE GENERAL THEME FOR
THE EXTENDED FORECAST PERIOD. MODERATE AGREEMENT EXISTS BETWEEN THE
VARIOUS DETERMINISTIC AND ENSEMBLE MODEL SOLUTIONS IN THE OVERALL
UPPER FLOW PATTERN CONSISTING OF HIGH PRESSURE OVER THE POLE AND
INTO THE HUDSON BAY AREA...AS WELL AS AN UPPER RIDGE JUST OFF THE
WEST COAST OF THE US. THE NCEP RELATIVE MEASURE OF PREDICTABILITY
VALUES ARE HIGH FOR THESE TWO ANCHORING FEATURES. THIS SOMEWHAT
STAGNATE NORTHERN HEMISPHERIC PATTERN IS FORECAST TO REMAIN IN PLACE
THROUGH THE EXTENDED PERIOD IN A BLOCKING FASHION... INDICATIVE OF
THE ON-GOING NEGATIVE PHASE OF THE ARCTIC OSCILLATION. THE SENSIBLE
WEATHER RESULTS WILL BE COLD TEMPERATURES AS THE POLAR JET CONTINUES
TO BE PUSHED INTO THE SOUTHERN US.
ALTHOUGH THE LARGE SCALE PATTERN CAN BE CHARACTERIZED AS
STAGNANT...SHORTWAVE ENERGY IS FORECAST TO RIDE THE FLOW OUT OF THE
NORTH PACIFIC...THROUGH SOUTHWEST CANADA AND INTO THE PLAINS. THESE
SHORTWAVES WILL ACT TO REINFORCE THE COOL TEMPERATURES...WITH THE
FORECAST AREA REMAINING BELOW 0C AT 850MB THROUGH THE PERIOD PER THE
DETERMINISTIC ECMWF/GFS/GEM. TEMPERATURES WILL REMAIN WELL BELOW
NORMAL INTO THE WEEKEND...RUNNING 10-20 DEGREES BELOW NORMAL MOST
AREAS.
THE SHORTWAVES WILL ALSO GENERATE VERTICAL MOTION RESULTING IN CLOUD
COVER AS WELL AS A CHANCE FOR PRECIPITATION. CONFIDENCE IS LOW FOR
PINNING DOWN THE TIMING ON THE PRECIP CHANCES...BUT FOR NOW WILL
CARRY A CHANCE OR SLIGHT CHANCE WEDNESDAY NIGHT INTO FRIDAY. THIS
SHOULD BE ALL LIGHT SNOW WITH THE EXCEPTION OF THURSDAY IN THE
SOUTHERN HALF OF THE AREA WHERE NEAR SURFACE TEMPERATURES MAY BE WARM
ENOUGH FOR A RAIN-SNOW MIX. AT THIS TIME WE ONLY EXPECT LIGHT
AMOUNTS GIVEN THE DISORGANIZED NATURE OF THE SHORTWAVES AND
RELATIVELY WEAK FEATURES.
NIETFELD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
621 PM CDT SUN MAR 17 2013
.AVIATION...
00Z TAFS FOR KOMA...KLNK...KOFK.
MAIN AVIATION CONCERN IS STILL THE TIMING OF PCPN/LOW CEILINGS
AND RESTRICTIONS TO VISIBILITY DEVELOPING THIS EVENING AND THEN
CONTINUING INTO THE OVERNIGHT HOURS. BAND OF PCPN IS EVIDENT ON
RADAR LOOP AND WILL BE MOVING EASTWARD. EXPECT AT LEAST TEMPO
IFR CONDITIONS WITH HEAVIEST PCPN. CONDITIONS SHOULD BECOME VFR
IN THE 09Z-12Z TIMEFRAME AT KOFK...10Z-13Z AT KLNK AND 12Z-15Z
AT KOMA. STRONG NORTHWEST WINDS WILL ALSO OVERSPREAD THE AREA
WITH GUSTS OVER 30 KNOTS. RAP MODEL IS QUITE GENEROUS WITH PCPN
AMOUNTS SO WILL HAVE TO MONITOR THAT THROUGH THE EVENING. WILL
AMEND AS NEEDED.
MILLER
&&
.PREV DISCUSSION... /ISSUED 305 PM CDT SUN MAR 17 2013/
SHORT TERM...TONIGHT THROUGH WEDNESDAY.
TEMPERATURES WILL BE THE PRIMARY FORECAST CONCERN IN THE SHORT
TERM WITH SNOWFALL POTENTIAL TONIGHT ALSO A FOCUS.
SURFACE LOW PRESSURE OVER WESTERN SOUTH DAKOTA AT 19Z WILL TRACK
ACROSS THE DAKOTAS TONIGHT REACHING NORTHERN MINNESOTA BY MONDAY
MORNING. A SURFACE TROUGH STRETCHING SOUTH FROM THE LOW WILL
MOVE ACROSS NEBRASKA OVERNIGHT AND ACT AS A FOCUS FOR SHOWERS
AS THE SYSTEM MOVES EAST. SOME POTENTIAL FOR SNOW TONIGHT BUT
SURFACE TEMPERATURES AND SPEED OF THE SYSTEM WILL BE LIMITING
FACTORS FOR MUCH ACCUMULATION. BEST LOCATION APPEARS TO BE WEST
CENTRAL IOWA WHERE BETTER THERMAL PROFILE IS EXPECTED. SOME
SNOW COVER ALSO REMAINS IN THIS AREA HELPING TO MAINTAIN COLDER
SURFACE TEMPERATURES. NONETHELESS...ONLY EXPECT SNOWFALL UP TO AN
INCH AFTER MIDNIGHT DUE TO THE SPEED OF THE SYSTEM.
COLD FRONT IS EXPECTED TO BE NEAR THE NEBRASKA SOUTH DAKOTA
BORDER BY MORNING AND WILL SWEEP ACROSS THE AREA BY AFTERNOON.
GUSTY NORTHWEST WINDS FOLLOW BEHIND THE FRONT AND MAY APPROACH
ADVISORY LEVELS ACROSS NORTHEAST NEBRASKA BY LATE MORNING. WILL
LET MIDNIGHT CREW DECIDE IF HEADLINES ARE NEEDED. AREA THEN
REMAINS UNDER COLD NORTHWEST FLOW THROUGH WEDNESDAY WITH PERIODS
OF CLOUDS BUT NO PRECIP AS WEAK WAVES DROP DOWN IN THE FLOW.
FOBERT
LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY.
COLD...CLOUDY...WITH A CHANCE OF LIGHT SNOW IS THE GENERAL THEME FOR
THE EXTENDED FORECAST PERIOD. MODERATE AGREEMENT EXISTS BETWEEN THE
VARIOUS DETERMINISTIC AND ENSEMBLE MODEL SOLUTIONS IN THE OVERALL
UPPER FLOW PATTERN CONSISTING OF HIGH PRESSURE OVER THE POLE AND
INTO THE HUDSON BAY AREA...AS WELL AS AN UPPER RIDGE JUST OFF THE
WEST COAST OF THE US. THE NCEP RELATIVE MEASURE OF PREDICTABILITY
VALUES ARE HIGH FOR THESE TWO ANCHORING FEATURES. THIS SOMEWHAT
STAGNATE NORTHERN HEMISPHERIC PATTERN IS FORECAST TO REMAIN IN PLACE
THROUGH THE EXTENDED PERIOD IN A BLOCKING FASHION... INDICATIVE OF
THE ON-GOING NEGATIVE PHASE OF THE ARCTIC OSCILLATION. THE SENSIBLE
WEATHER RESULTS WILL BE COLD TEMPERATURES AS THE POLAR JET CONTINUES
TO BE PUSHED INTO THE SOUTHERN US.
ALTHOUGH THE LARGE SCALE PATTERN CAN BE CHARACTERIZED AS
STAGNANT...SHORTWAVE ENERGY IS FORECAST TO RIDE THE FLOW OUT OF THE
NORTH PACIFIC...THROUGH SOUTHWEST CANADA AND INTO THE PLAINS. THESE
SHORTWAVES WILL ACT TO REINFORCE THE COOL TEMPERATURES...WITH THE
FORECAST AREA REMAINING BELOW 0C AT 850MB THROUGH THE PERIOD PER THE
DETERMINISTIC ECMWF/GFS/GEM. TEMPERATURES WILL REMAIN WELL BELOW
NORMAL INTO THE WEEKEND...RUNNING 10-20 DEGREES BELOW NORMAL MOST
AREAS.
THE SHORTWAVES WILL ALSO GENERATE VERTICAL MOTION RESULTING IN CLOUD
COVER AS WELL AS A CHANCE FOR PRECIPITATION. CONFIDENCE IS LOW FOR
PINNING DOWN THE TIMING ON THE PRECIP CHANCES...BUT FOR NOW WILL
CARRY A CHANCE OR SLIGHT CHANCE WEDNESDAY NIGHT INTO FRIDAY. THIS
SHOULD BE ALL LIGHT SNOW WITH THE EXCEPTION OF THURSDAY IN THE
SOUTHERN HALF OF THE AREA WHERE NEAR SURFACE TEMPERATURES MAY BE WARM
ENOUGH FOR A RAIN-SNOW MIX. AT THIS TIME WE ONLY EXPECT LIGHT
AMOUNTS GIVEN THE DISORGANIZED NATURE OF THE SHORTWAVES AND
RELATIVELY WEAK FEATURES.
NIETFELD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1223 PM CDT SAT MAR 16 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 420 AM CDT SAT MAR 16 2013
WEATHER CONCERNS IN THE SHORT TERM CENTER AROUND LOW CLOUD
COVER/TEMPS TODAY...AND INCREASING PCPN CHCS TONIGHT.
THE PATTERN ALOFT FEATURED WEST TO NORTHWEST FLOW ACROSS THE CONUS
WITH THE MAIN JETS ACROSS THE UPPER MIDWEST/GREAT LAKES REGION AND
NOSING ACROSS THE CENTRAL ROCKIES. SURFACE COLD FRONT WHICH CROSSED
OUR REGION FRIDAY EVENING WAS LOCATED IN SOUTHERN KS EARLY THIS
MORNING. STRATUS HAS BEEN ADVECTING SOUTH FM SOUTH DAKOTA/NORTHEAST
NEBRASKA...AND HAS REACHED THE ORD AND YORK AREAS BY 08Z. HRRR HAS
BEEN DOING A DECENT JOB WITH THE LOW CLOUDS AND SETTLES THE STRATUS
ACROSS OUR EASTERN/NORTHEASTERN ZONES. WITH THE LOW CLOUDS IN PLACE
IN OUR EAST...JUST NOT LOOKING AT MUCH IN THE WAY OF A TEMP WARMUP
WITH HIGHS AVERAGING IN THE MID/UPPER 30S. FARTHER SOUTH AND WEST...TEMPS
SHOULD AVERAGE IN THE MID/UPPER 40S IN PRESENCE OF MID/HIGH
CLOUDS.
RADAR RETURNS IN WESTERN NEB HAVE YIELDED A SPRINKLE/BRIEF SHOWER AT
THEDFORD BUT PCPN REPORTS HAVE BEEN FEW AND FAR BETWEEN. CANNOT
COMPLETELY RULE OUT A SPRINKLE/SHOWER ACROSS OUR NORTH THIS
MORNING...HOWEVER CHCS INCREASE THIS AFTN/TONIGHT AS PCPN IN UPSLOPE
FLOW ALONG THE HIGH PLAINS SPREADS EAST AS MID LEVEL SHORTWAVE
TROUGH TRANSLATES EAST ACROSS THE CENTRAL PLAINS...WITH LIFT
ENHANCED IN RRQ OF 95KT H3 JET STREAK. LIFT THEN FOCUSES ACROSS NC
KS TONIGHT ALONG MID LEVEL FRONTAL BOUNDARY WITH GOOD FRONTOGENESIS
PROGGED BETWEEN H7 AND H5.
PCPN TYPE LOOKS TO INITIALLY BEGIN AS LIQUID...THEN TRANSITION TO
R/S NORTH TO SOUTH TONIGHT AS THERMAL PROFILE COOLS. FORECAST
SOUNDINGS AND THICKNESSES SUGGEST A CHANGE TO SNOW ACROSS PORTIONS
OF SC NEB...WITH R/S OR PERHAPS A PERIOD OF FREEZING PCPN ACROSS NC
KANSAS WITH MID LEVEL TEMPS HOVERING NEAR/JUST ABOVE FREEZING
FOLLOWED BY A LOSS OF DENDRITIC MOISTURE BY 12Z SUNDAY. SFC WET
BULB TEMPS AND FORECAST LOW TEMPS ONLY BRIEFLY DROP BELOW FREEZING
SO GENERALLY NOT EXPECTING MUCH IN THE WAY OF FREEZING PCPN AND
WILL KEEP THINGS AS R/S ATTM. SPC SNOW PLUMES SUGGEST SNOW AMOUNTS
WILL AVERAGE ONE HALF INCH OR LESS AND HAVE FOLLOWED THIS TREND
AND REDUCED OVERALL SNOWFALL POTENTIAL GIVEN PROGRESSIVE NATURE OF
SYSTEM. PCPN WINDS DOWN TOWARD DAYBREAK ON SUNDAY BEHIND DEPARTING
WAVE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 420 AM CDT SAT MAR 16 2013
PATTERN: PNA FCSTS VIA THE GFS/EC AND THEIR ENSEMBLES TURNS NEGATIVE
THE NEXT 7 DAYS...THEN TURNS POSITIVE THE LAST WEEK OF MARCH. OVERALL
THE NAO WILL REMAIN NEGATIVE THE REST OF THE MONTH. THE PNA FCSTS
SUGGEST THE LONG-WAVE PATTERN WILL BE SLOWLY PROGRESSIVE...WITH THE
WRN USA RIDGE OF THE PAST COUPLE DAYS TRANSITIONING TO A TROF.
ANOTHER RIDGE MOVES THRU WED FOLLOWED BY THE NEXT TROF. WITH BOTH
TELECONNECTIONS NEGATIVE...THIS FAVORS BELOW NORMAL HGTS AND BELOW
NORMAL TEMPS OVER THE CONUS FOR THE NEXT 7 DAYS. THE LAST WEEK OF
THE MONTH...A RIDGE WILL BUILD OVER THE W. WITH CONTINUED TROFFING
OVER THE E...THIS WILL TRANSPORT MORE COLD AIR OUT OF CANADA. AND
WHILE THE CORE OF THE COLDEST AIR WILL REMAIN OVER THE ERN USA...ITS
WRN FRINGE WILL STILL AFFECT US HERE.
A FEW DAYS AGO...IT LOOKED LIKE THE NEGATIVE SPIKE IN THE PNA WOULD
DELIVER ANOTHER LEE CYCLOGENESIS EVENT. THIS IS STILL ON THE TABLE
BUT WITH DENSE COLD AIR IN PLACE...A SUPPRESSED LOW TRACK IS
EXPECTED OVER TX ALONG THE FRONT. THE COLD ARRIVES TOO SOON THIS
TIME FOR ANOTHER SNOWSTORM.
FCST CONFIDENCE: AVERAGE ON THE OVERALL TRENDS. BELOW AVERAGE ON THE
DETAILS THU-FRI DUE TO MODEL STRUGGLES WITH BLOCKING FROM CNTRL
CANADA INTO NEW ENGLAND...WHICH BACKS THINGS UP HERE IN THE PLAINS.
HAZARDS: WIND ADVISORY IS "POSSIBLE" MON. PROBABILITY IS LOW.
THE DAILY DETAILS...
SUN NGT: COLD FRONTAL PASSAGE /CFP/ WITH A QUICK BURST OF SHWRS. WE
MAY NEED TO ADD THUNDER W OF HWY 281. THIS IS A POTENT SHORT-WAVE
/SHRTWV/ TROF. MID-LEVEL LAPSE RATES ARE STEEP 7-8 C/KM IN THE LFQ
OF A 90 KT JET STREAK. NAM THUNDER PROBS ARE UP TO 40 PERCENT.
THESE SHWRS SHOULD OCCUR IN THE WARM BOUNDARY LAYER AHEAD OF THE
COLD FRONT. SO PCPN TYPE WAS CHANGED TO RAIN. ALSO TRIMMED POPS
AFTER MIDNGT AS THESE SHWRS WILL BE BRIEF...THEN CLEARING SKIES.
MON: DRY WITH A PERIOD OF BLUSTERY NW WINDS. THE GFS IS THE ONLY
MODEL THAT CRANKS THE WINDS TO ADVISORY CRITERIA...WHICH LOWERS
CONFIDENCE. FOR NOW PLAYED IT CONSERVATIVE BUT MAINTAINED MENTION IN
THE HWO SINCE IT STILL IS WITHIN THE REALM OF POSSIBILITY.
MON NGT: CAN ENVISION NEEDING TO INTRODUCE A POP FOR SOME SNOW
SHWRS. THE LAST 3 CYCLES OF THE EC HAVE DUMPED A FEW HUNDREDTHS WITH
SOME SREF SUPPORT.
TUE-WED: QUIET AND DRY. ANOTHER COLD FRONT MOVES THRU TUE NGT. SO
NEAR NORMAL TEMPS TUE WILL TURN BELOW NORMAL WED.
THU-THU NGT: COULD BE INTERESTING OR IT COULD BE A MISS. MODELS ARE
DUMPING A LOT OF QPF OVER OR VERY CLOSE TO THE FCST AREA. A PAC
SHRTWV TROF RACES ACROSS THE ROCKIES AND ONTO THE PLAINS...BUT
WHERE? THIS SYSTEM THREATENS A SNOWSTORM BUT UNCERTAINTY ABOUNDS ON
ITS LOCATION. STAY TUNED.
FRI-MON: TEMPS MUCH BELOW NORMAL. H8 TEMPS ARE FCST -1 STANDARD
DEVIATION. SEVERAL MODELS OFFER HIGHS IN THE 20S FRI.
AVG MARCH TEMP: AVG DAILY TEMPS WILL BE AT OR BELOW NORMAL THE REST
OF THE MONTH. ODDS ARE VERY HIGH THIS WILL BE THE COOLEST MARCH AT
GRI /AND THE REST OF THE FCST AREA/ SINCE 2002. 12Z/15 NAEFS
PROBABILITIES FOR BELOW NORMAL TEMPS ARE 70-80 PERCENT FOR MAR
23-30TH.
&&
.AVIATION...(FOR THE 18Z TAF THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1220 PM CDT SAT MAR 16 2013
MVFR STRATUS CONTINUES TO REMAIN JUST TO THE NORTH AND EAST OF THE
TERMINAL. MAY STILL AFFECT KGRI THIS AFTERNOON BUT BETTER CHANCE
FOR LOWER CEILINGS COMES LATER THIS EVENING AND OVERNIGHT WHEN
UPSTREAM WAVE MOVES ACROSS THE REGION FROM THE WEST. ALSO A CHANCE
FOR SOME LIGHT RAIN OR SNOW WITH THIS SYSTEM. EXPECT TO REMAIN IN
MVFR TO IFR CONDITIONS OVERNIGHT AND DURING THE MORNING HOURS ON
SUNDAY. WINDS SHOULD GRADUALLY TURN FROM NORTHEAST TO SOUTHEAST
AS SURFACE HIGH PRESSURE TO THE NORTH TRACKS EAST.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...FAY
LONG TERM...HALBLAUB
AVIATION...EWALD
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
627 AM CDT SAT MAR 16 2013
.AVIATION...
12Z TAFS FOR KOMA...KLNK...KOFK.
WINDS AND VARIABLE IFR/MVFR/VFR CLOUD CIGS WILL BE THE FORECAST
CONCERNS FOR TODAY. ALTHOUGH THERE WILL BE SOME HIT AND MISS
SPRINKLES WITH THE STRONGER RADAR ECHOES...TIME OF ANY PRECIP TOO
SMALL TO INCLUDED IN THE TAFS. WHEN THE WINDS PICKED UP THIS
MORNING...SO DID THE FOG VISIBILITIES. SOME PATCHY MVFR VSBYS AND
AREAS OF IFR/MVFR CLOUDS CEILINGS TO START THIS MORNING. NORTH
WINDS 10 TO 20KTS WITH HIGHS GUSTS DECREASING TO 10 TO 15KTS THIS
AFTERNOON. KOFK DID SCATTERED OUT THEIR LOW CLOUDS...HOWEVER
THERE ARE SOME MORE LOW CLOUDS UPSTREAM. THE HRRR HAS DONE WELL
WITH THE CLOUDS AND KEEPS KOMA/KLNK IN THE LOW CLOUDS THROUGH
EARLY AFTERNOON WITH SOME IMPROVEMENT LATE THIS AFTERNOON.
TONIGHT...A WEATHER SYSTEM WILL BRING PRECIPITATION TO PARTS OF
NEBRASKA AND KANSAS...AND KLNK COULD RETURN TO MVF/IFR TONIGHT.
KOFK WILL BE VARIABLE MVFR THIS MORNING...BUT TRENDING TO VFR WITH
MID AND HIGH CLOUDS.
ZAPOTOCNY
&&
.PREV DISCUSSION... /ISSUED 319 AM CDT SAT MAR 16 2013/
DISCUSSION...
COOL TEMPERATURES THROUGH THE BEGINNING OF THE WEEK...WITH A CHANCE
FOR ACCUMULATING SNOW SUNDAY NIGHT...ARE THE PRIMARY FORECAST
CONCERNS.
COLD FRONT THAT MOVED THROUGH OUR AREA FRIDAY HAS SETTLED WELL SOUTH
INTO SOUTHERN KANSAS. BEHIND THE FRONT LOW CLOUDS HAVE SPILLED
ACROSS MOST OF EASTERN NEBRASKA AND WESTERN IOWA...WITH GUSTY NORTH
WINDS DRIVING TEMPERATURES THROUGH THE 30S THIS MORNING. SURFACE
HIGH PRESSURE FROM THE NORTHERN PLAINS WAS RIDGING INTO THE MID
MISSOURI RIVER VALLEY...AND IS EXPECTED TO REMAIN IN PLACE THROUGH
THE DAY. SO GIVEN CONTINUED COOL ADVECTION AND STUBBORN CLOUD
COVER...DO NOT EXPECT TEMPERATURES TO REBOUND MUCH THIS AFTERNOON.
HAVE HIGHS IN THE 30S NORTH TO THE LOWER 40S SOUTH.
OUR NEXT DOMINANT WEATHER MAKER IN THE FORM OF A MID LEVEL TROUGH
WILL BE MOVING THROUGH THE CENTRAL AND NORTHERN ROCKIES ON
SUNDAY...THEN SWEEPING THROUGH OUR AREA EARLY MONDAY MORNING. AHEAD
OF THIS FEATURE...LOWERING SURFACE PRESSURES IN THE LEE OF THE
ROCKIES WILL BRING SOUTHERLY FLOW TO THE REGION ON SUNDAY. THIS
SUGGESTS AFTERNOON HIGHS WILL BE WARMER ON SUNDAY DESPITE A COOLER
START IN THE 20S UNDER LIGHT WIND REGIME AND DECREASING CLOUDS. HAVE
HIGHS SUNDAY IN THE 40S ALL AREAS WITH GUSTY SOUTH WINDS.
COLD FRONT ASSOCIATED WITH MID LEVEL TROUGH SHOULD BE APPROACHING
OUR NORTHWEST CWA SUNDAY EVENING. MODELS HAVE INCREASED THE SPEED OF
THIS SYSTEM...SO THERE IS A SHORTER WINDOW OF POTENTIAL
PRECIPITATION SUNDAY NIGHT...CLOSER TO A 6 HOUR DURATION RATHER THAN
9 OR 12 AS PER PREVIOUS RUNS. BUT THAT 6 HOUR WINDOW COULD BRING
BRIEF MODERATE PRECIPITATION AS A RIBBON OF STRONG THETA-E ADVECTION
PRECEDES THE FRONT. PRECIPITATION TYPE IS STILL SOMEWHAT IN QUESTION
AS FORECAST SOUNDINGS SUGGEST ABOVE FREEZING AIR WILL BE MAINTAINED
FOR A COUPLE OF HOURS AFTER FRONTAL PASSAGE BEFORE A CHANGE TO ALL
SNOW. SLEET LOOKS LIKE A GOOD BET FOR A TIME WHICH WILL CUT INTO
POTENTIAL SNOWFALL. FOR NOW WILL MENTION ONLY RAIN OR SNOW BEFORE
CHANGING TO ALL SNOW AS THE NIGHT WEARS ON...AND TAKE A CLOSER LOOK
AT SLEET POTENTIAL WITH LATER FORECASTS. LOOKS LIKE AN INCH OR TWO
OF SNOW COULD ACCUMULATE IN OUR NORTH WHERE TEMPERATURES WILL COOL
SOONER...AND NO ACCUMULATION IN THE SOUTH.
WITH THE FASTER MOVEMENT OF THE SYSTEM...AM NOT EXPECTING
PRECIPITATION TO LAST PAST 12Z MONDAY. HOWEVER WINDS LOOK TO BE THE
PRIMARY CONCERN THEN AS STRONG COLD ADVECTION UNDER UNIDIRECTIONAL
LAYERED WINDS PROMOTE EFFICIENT MOMENTUM TRANSFER OF 35+ KT 850 FLOW
TO THE SURFACE. A WIND ADVISORY MAY BE NEEDED MONDAY AS WINDS GUST
OVER 40 MPH. TEMPERATURES SHOULD ONLY REACH THE 30S TO LOWER 40S.
THE REST OF THE WEEK IS LOOKING MORE MESSY THAN WHAT WE SAW
YESTERDAY. SUNDAY NIGHTS MID LEVEL TROUGH IS FORECAST TO WIND UP
INTO A CLOSED LOW OVER THE GREAT LAKES AND NEW ENGLAND BY
WEDNESDAY...LEAVING THE MIDDLE OF THE COUNTRY UNDER WEAK FLOW
REGIME. HOWEVER BOTH GFS AND ECMWF DRAG A WEAK LOW CIRCULATION INTO
THE PLAINS THURSDAY AND LINGER IT INTO THE WEEKEND. TRYING TO NAIL
DOWN TIMING AND TRACK OF THIS SYSTEM WILL BE FUTILE THIS FAR
OUT...SO OUR FORECAST WILL REFLECT A BLENDED SOLUTION OF OUR CURRENT
FORECAST WITH THE GFS AND ECMWF. THERE IS CERTAINLY A CHANCE FOR
PRECIPITATION LATE THIS WEEK...BUT THERE ARE AT LEAST EQUAL CHANCES
THAT PRECIP WILL REMAIN WEST AND SOUTH OF OUR AREA.
DERGAN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
530 AM CDT SAT MAR 16 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 420 AM CDT SAT MAR 16 2013
WEATHER CONCERNS IN THE SHORT TERM CENTER AROUND LOW CLOUD
COVER/TEMPS TODAY...AND INCREASING PCPN CHCS TONIGHT.
THE PATTERN ALOFT FEATURED WEST TO NORTHWEST FLOW ACROSS THE CONUS
WITH THE MAIN JETS ACROSS THE UPPER MIDWEST/GREAT LAKES REGION AND
NOSING ACROSS THE CENTRAL ROCKIES. SURFACE COLD FRONT WHICH CROSSED
OUR REGION FRIDAY EVENING WAS LOCATED IN SOUTHERN KS EARLY THIS
MORNING. STRATUS HAS BEEN ADVECTING SOUTH FM SOUTH DAKOTA/NORTHEAST
NEBRASKA...AND HAS REACHED THE ORD AND YORK AREAS BY 08Z. HRRR HAS
BEEN DOING A DECENT JOB WITH THE LOW CLOUDS AND SETTLES THE STRATUS
ACROSS OUR EASTERN/NORTHEASTERN ZONES. WITH THE LOW CLOUDS IN PLACE
IN OUR EAST...JUST NOT LOOKING AT MUCH IN THE WAY OF A TEMP WARMUP
WITH HIGHS AVERAGING IN THE MID/UPPER 30S. FARTHER SOUTH AND WEST...TEMPS
SHOULD AVERAGE IN THE MID/UPPER 40S IN PRESENCE OF MID/HIGH
CLOUDS.
RADAR RETURNS IN WESTERN NEB HAVE YIELDED A SPRINKLE/BRIEF SHOWER AT
THEDFORD BUT PCPN REPORTS HAVE BEEN FEW AND FAR BETWEEN. CANNOT
COMPLETELY RULE OUT A SPRINKLE/SHOWER ACROSS OUR NORTH THIS
MORNING...HOWEVER CHCS INCREASE THIS AFTN/TONIGHT AS PCPN IN UPSLOPE
FLOW ALONG THE HIGH PLAINS SPREADS EAST AS MID LEVEL SHORTWAVE
TROUGH TRANSLATES EAST ACROSS THE CENTRAL PLAINS...WITH LIFT
ENHANCED IN RRQ OF 95KT H3 JET STREAK. LIFT THEN FOCUSES ACROSS NC
KS TONIGHT ALONG MID LEVEL FRONTAL BOUNDARY WITH GOOD FRONTOGENESIS
PROGGED BETWEEN H7 AND H5.
PCPN TYPE LOOKS TO INITIALLY BEGIN AS LIQUID...THEN TRANSITION TO
R/S NORTH TO SOUTH TONIGHT AS THERMAL PROFILE COOLS. FORECAST
SOUNDINGS AND THICKNESSES SUGGEST A CHANGE TO SNOW ACROSS PORTIONS
OF SC NEB...WITH R/S OR PERHAPS A PERIOD OF FREEZING PCPN ACROSS NC
KANSAS WITH MID LEVEL TEMPS HOVERING NEAR/JUST ABOVE FREEZING
FOLLOWED BY A LOSS OF DENDRITIC MOISTURE BY 12Z SUNDAY. SFC WET
BULB TEMPS AND FORECAST LOW TEMPS ONLY BRIEFLY DROP BELOW FREEZING
SO GENERALLY NOT EXPECTING MUCH IN THE WAY OF FREEZING PCPN AND
WILL KEEP THINGS AS R/S ATTM. SPC SNOW PLUMES SUGGEST SNOW AMOUNTS
WILL AVERAGE ONE HALF INCH OR LESS AND HAVE FOLLOWED THIS TREND
AND REDUCED OVERALL SNOWFALL POTENTIAL GIVEN PROGRESSIVE NATURE OF
SYSTEM. PCPN WINDS DOWN TOWARD DAYBREAK ON SUNDAY BEHIND DEPARTING
WAVE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 420 AM CDT SAT MAR 16 2013
PATTERN: PNA FCSTS VIA THE GFS/EC AND THEIR ENSEMBLES TURNS NEGATIVE
THE NEXT 7 DAYS...THEN TURNS POSITIVE THE LAST WEEK OF MARCH. OVERALL
THE NAO WILL REMAIN NEGATIVE THE REST OF THE MONTH. THE PNA FCSTS
SUGGEST THE LONG-WAVE PATTERN WILL BE SLOWLY PROGRESSIVE...WITH THE
WRN USA RIDGE OF THE PAST COUPLE DAYS TRANSITIONING TO A TROF.
ANOTHER RIDGE MOVES THRU WED FOLLOWED BY THE NEXT TROF. WITH BOTH
TELECONNECTIONS NEGATIVE...THIS FAVORS BELOW NORMAL HGTS AND BELOW
NORMAL TEMPS OVER THE CONUS FOR THE NEXT 7 DAYS. THE LAST WEEK OF
THE MONTH...A RIDGE WILL BUILD OVER THE W. WITH CONTINUED TROFFING
OVER THE E...THIS WILL TRANSPORT MORE COLD AIR OUT OF CANADA. AND
WHILE THE CORE OF THE COLDEST AIR WILL REMAIN OVER THE ERN USA...ITS
WRN FRINGE WILL STILL AFFECT US HERE.
A FEW DAYS AGO...IT LOOKED LIKE THE NEGATIVE SPIKE IN THE PNA WOULD
DELIVER ANOTHER LEE CYCLOGENESIS EVENT. THIS IS STILL ON THE TABLE
BUT WITH DENSE COLD AIR IN PLACE...A SUPPRESSED LOW TRACK IS
EXPECTED OVER TX ALONG THE FRONT. THE COLD ARRIVES TOO SOON THIS
TIME FOR ANOTHER SNOWSTORM.
FCST CONFIDENCE: AVERAGE ON THE OVERALL TRENDS. BELOW AVERAGE ON THE
DETAILS THU-FRI DUE TO MODEL STRUGGLES WITH BLOCKING FROM CNTRL
CANADA INTO NEW ENGLAND...WHICH BACKS THINGS UP HERE IN THE PLAINS.
HAZARDS: WIND ADVISORY IS "POSSIBLE" MON. PROBABILITY IS LOW.
THE DAILY DETAILS...
SUN NGT: COLD FRONTAL PASSAGE /CFP/ WITH A QUICK BURST OF SHWRS. WE
MAY NEED TO ADD THUNDER W OF HWY 281. THIS IS A POTENT SHORT-WAVE
/SHRTWV/ TROF. MID-LEVEL LAPSE RATES ARE STEEP 7-8 C/KM IN THE LFQ
OF A 90 KT JET STREAK. NAM THUNDER PROBS ARE UP TO 40 PERCENT.
THESE SHWRS SHOULD OCCUR IN THE WARM BOUNDARY LAYER AHEAD OF THE
COLD FRONT. SO PCPN TYPE WAS CHANGED TO RAIN. ALSO TRIMMED POPS
AFTER MIDNGT AS THESE SHWRS WILL BE BRIEF...THEN CLEARING SKIES.
MON: DRY WITH A PERIOD OF BLUSTERY NW WINDS. THE GFS IS THE ONLY
MODEL THAT CRANKS THE WINDS TO ADVISORY CRITERIA...WHICH LOWERS
CONFIDENCE. FOR NOW PLAYED IT CONSERVATIVE BUT MAINTAINED MENTION IN
THE HWO SINCE IT STILL IS WITHIN THE REALM OF POSSIBILITY.
MON NGT: CAN ENVISION NEEDING TO INTRODUCE A POP FOR SOME SNOW
SHWRS. THE LAST 3 CYCLES OF THE EC HAVE DUMPED A FEW HUNDREDTHS WITH
SOME SREF SUPPORT.
TUE-WED: QUIET AND DRY. ANOTHER COLD FRONT MOVES THRU TUE NGT. SO
NEAR NORMAL TEMPS TUE WILL TURN BELOW NORMAL WED.
THU-THU NGT: COULD BE INTERESTING OR IT COULD BE A MISS. MODELS ARE
DUMPING A LOT OF QPF OVER OR VERY CLOSE TO THE FCST AREA. A PAC
SHRTWV TROF RACES ACROSS THE ROCKIES AND ONTO THE PLAINS...BUT
WHERE? THIS SYSTEM THREATENS A SNOWSTORM BUT UNCERTAINTY ABOUNDS ON
ITS LOCATION. STAY TUNED.
FRI-MON: TEMPS MUCH BELOW NORMAL. H8 TEMPS ARE FCST -1 STANDARD
DEVIATION. SEVERAL MODELS OFFER HIGHS IN THE 20S FRI.
AVG MARCH TEMP: AVG DAILY TEMPS WILL BE AT OR BELOW NORMAL THE REST
OF THE MONTH. ODDS ARE VERY HIGH THIS WILL BE THE COOLEST MARCH AT
GRI /AND THE REST OF THE FCST AREA/ SINCE 2002. 12Z/15 NAEFS
PROBABILITIES FOR BELOW NORMAL TEMPS ARE 70-80 PERCENT FOR MAR
23-30TH.
&&
.AVIATION...(FOR THE 12Z TAF THROUGH 12Z SUNDAY MORNING)
ISSUED AT 520 AM CDT SAT MAR 16 2013
CHALLENGING TAF PERIOD THIS MORNING DUE TO PERIODS OF IFR TO MVFR
STRATUS PASSING BY THE TERMINAL. MVFR CLOUDS HAVE SCATTERED ATTM
HOWEVER LOW CLOUDS REMAIN UPSTREAM AND FORECAST MODELS SUGGEST THE
LOW CLOUDS WILL SETTLE IN TODAY AND HAVE MAINTAINED MVFR CLOUDS INTO
TONIGHT. PCPN CHCS INCREASE BY LATE EVENING AS AN UPPER LEVEL
DISTURBANCE CROSSES THE CENTRAL PLAINS AND A FEW HOUR PERIOD OF
R/S CANNOT BE RULED OUT. CIGS LOWER DURING THE NIGHT...AND WINDS
TRANSITION E/SE ON BACK SIDE OF SFC RIDGE. VSBYS MAY DROP IN BR ALONG
SFC RIDGE AXIS TOWARD SUNDAY MORNING.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...FAY
LONG TERM...HALBLAUB
AVIATION...FAY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
427 AM CDT SAT MAR 16 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 420 AM CDT SAT MAR 16 2013
WEATHER CONCERNS IN THE SHORT TERM CENTER AROUND LOW CLOUD
COVER/TEMPS TODAY...AND INCREASING PCPN CHCS TONIGHT.
THE PATTERN ALOFT FEATURED WEST TO NORTHWEST FLOW ACROSS THE CONUS
WITH THE MAIN JETS ACROSS THE UPPER MIDWEST/GREAT LAKES REGION AND
NOSING ACROSS THE CENTRAL ROCKIES. SURFACE COLD FRONT WHICH CROSSED
OUR REGION FRIDAY EVENING WAS LOCATED IN SOUTHERN KS EARLY THIS
MORNING. STRATUS HAS BEEN ADVECTING SOUTH FM SOUTH DAKOTA/NORTHEAST
NEBRASKA...AND HAS REACHED THE ORD AND YORK AREAS BY 08Z. HRRR HAS
BEEN DOING A DECENT JOB WITH THE LOW CLOUDS AND SETTLES THE STRATUS
ACROSS OUR EASTERN/NORTHEASTERN ZONES. WITH THE LOW CLOUDS IN PLACE
IN OUR EAST...JUST NOT LOOKING AT MUCH IN THE WAY OF A TEMP WARMUP
WITH HIGHS AVERAGING IN THE MID/UPPER 30S. FARTHER SOUTH AND WEST...TEMPS
SHOULD AVERAGE IN THE MID/UPPER 40S IN PRESENCE OF MID/HIGH
CLOUDS.
RADAR RETURNS IN WESTERN NEB HAVE YIELDED A SPRINKLE/BRIEF SHOWER AT
THEDFORD BUT PCPN REPORTS HAVE BEEN FEW AND FAR BETWEEN. CANNOT
COMPLETELY RULE OUT A SPRINKLE/SHOWER ACROSS OUR NORTH THIS
MORNING...HOWEVER CHCS INCREASE THIS AFTN/TONIGHT AS PCPN IN UPSLOPE
FLOW ALONG THE HIGH PLAINS SPREADS EAST AS MID LEVEL SHORTWAVE
TROUGH TRANSLATES EAST ACROSS THE CENTRAL PLAINS...WITH LIFT
ENHANCED IN RRQ OF 95KT H3 JET STREAK. LIFT THEN FOCUSES ACROSS NC
KS TONIGHT ALONG MID LEVEL FRONTAL BOUNDARY WITH GOOD FRONTOGENESIS
PROGGED BETWEEN H7 AND H5.
PCPN TYPE LOOKS TO INITIALLY BEGIN AS LIQUID...THEN TRANSITION TO
R/S NORTH TO SOUTH TONIGHT AS THERMAL PROFILE COOLS. FORECAST
SOUNDINGS AND THICKNESSES SUGGEST A CHANGE TO SNOW ACROSS PORTIONS
OF SC NEB...WITH R/S OR PERHAPS A PERIOD OF FREEZING PCPN ACROSS NC
KANSAS WITH MID LEVEL TEMPS HOVERING NEAR/JUST ABOVE FREEZING
FOLLOWED BY A LOSS OF DENDRITIC MOISTURE BY 12Z SUNDAY. SFC WET
BULB TEMPS AND FORECAST LOW TEMPS ONLY BRIEFLY DROP BELOW FREEZING
SO GENERALLY NOT EXPECTING MUCH IN THE WAY OF FREEZING PCPN AND
WILL KEEP THINGS AS R/S ATTM. SPC SNOW PLUMES SUGGEST SNOW AMOUNTS
WILL AVERAGE ONE HALF INCH OR LESS AND HAVE FOLLOWED THIS TREND
AND REDUCED OVERALL SNOWFALL POTENTIAL GIVEN PROGRESSIVE NATURE OF
SYSTEM. PCPN WINDS DOWN TOWARD DAYBREAK ON SUNDAY BEHIND DEPARTING
WAVE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 420 AM CDT SAT MAR 16 2013
PATTERN: PNA FCSTS VIA THE GFS/EC AND THEIR ENSEMBLES TURNS NEGATIVE
THE NEXT 7 DAYS...THEN TURNS POSITIVE THE LAST WEEK OF MARCH. OVERALL
THE NAO WILL REMAIN NEGATIVE THE REST OF THE MONTH. THE PNA FCSTS
SUGGEST THE LONG-WAVE PATTERN WILL BE SLOWLY PROGRESSIVE...WITH THE
WRN USA RIDGE OF THE PAST COUPLE DAYS TRANSITIONING TO A TROF.
ANOTHER RIDGE MOVES THRU WED FOLLOWED BY THE NEXT TROF. WITH BOTH
TELECONNECTIONS NEGATIVE...THIS FAVORS BELOW NORMAL HGTS AND BELOW
NORMAL TEMPS OVER THE CONUS FOR THE NEXT 7 DAYS. THE LAST WEEK OF
THE MONTH...A RIDGE WILL BUILD OVER THE W. WITH CONTINUED TROFFING
OVER THE E...THIS WILL TRANSPORT MORE COLD AIR OUT OF CANADA. AND
WHILE THE CORE OF THE COLDEST AIR WILL REMAIN OVER THE ERN USA...ITS
WRN FRINGE WILL STILL AFFECT US HERE.
A FEW DAYS AGO...IT LOOKED LIKE THE NEGATIVE SPIKE IN THE PNA WOULD
DELIVER ANOTHER LEE CYCLOGENESIS EVENT. THIS IS STILL ON THE TABLE
BUT WITH DENSE COLD AIR IN PLACE...A SUPPRESSED LOW TRACK IS
EXPECTED OVER TX ALONG THE FRONT. THE COLD ARRIVES TOO SOON THIS
TIME FOR ANOTHER SNOWSTORM.
FCST CONFIDENCE: AVERAGE ON THE OVERALL TRENDS. BELOW AVERAGE ON THE
DETAILS THU-FRI DUE TO MODEL STRUGGLES WITH BLOCKING FROM CNTRL
CANADA INTO NEW ENGLAND...WHICH BACKS THINGS UP HERE IN THE PLAINS.
HAZARDS: WIND ADVISORY IS "POSSIBLE" MON. PROBABILITY IS LOW.
THE DAILY DETAILS...
SUN NGT: COLD FRONTAL PASSAGE /CFP/ WITH A QUICK BURST OF SHWRS. WE
MAY NEED TO ADD THUNDER W OF HWY 281. THIS IS A POTENT SHORT-WAVE
/SHRTWV/ TROF. MID-LEVEL LAPSE RATES ARE STEEP 7-8 C/KM IN THE LFQ
OF A 90 KT JET STREAK. NAM THUNDER PROBS ARE UP TO 40 PERCENT.
THESE SHWRS SHOULD OCCUR IN THE WARM BOUNDARY LAYER AHEAD OF THE
COLD FRONT. SO PCPN TYPE WAS CHANGED TO RAIN. ALSO TRIMMED POPS
AFTER MIDNGT AS THESE SHWRS WILL BE BRIEF...THEN CLEARING SKIES.
MON: DRY WITH A PERIOD OF BLUSTERY NW WINDS. THE GFS IS THE ONLY
MODEL THAT CRANKS THE WINDS TO ADVISORY CRITERIA...WHICH LOWERS
CONFIDENCE. FOR NOW PLAYED IT CONSERVATIVE BUT MAINTAINED MENTION IN
THE HWO SINCE IT STILL IS WITHIN THE REALM OF POSSIBILITY.
MON NGT: CAN ENVISION NEEDING TO INTRODUCE A POP FOR SOME SNOW
SHWRS. THE LAST 3 CYCLES OF THE EC HAVE DUMPED A FEW HUNDREDTHS WITH
SOME SREF SUPPORT.
TUE-WED: QUIET AND DRY. ANOTHER COLD FRONT MOVES THRU TUE NGT. SO
NEAR NORMAL TEMPS TUE WILL TURN BELOW NORMAL WED.
THU-THU NGT: COULD BE INTERESTING OR IT COULD BE A MISS. MODELS ARE
DUMPING A LOT OF QPF OVER OR VERY CLOSE TO THE FCST AREA. A PAC
SHRTWV TROF RACES ACROSS THE ROCKIES AND ONTO THE PLAINS...BUT
WHERE? THIS SYSTEM THREATENS A SNOWSTORM BUT UNCERTAINTY ABOUNDS ON
ITS LOCATION. STAY TUNED.
FRI-MON: TEMPS MUCH BELOW NORMAL. H8 TEMPS ARE FCST -1 STANDARD
DEVIATION. SEVERAL MODELS OFFER HIGHS IN THE 20S FRI.
AVG MARCH TEMP: AVG DAILY TEMPS WILL BE AT OR BELOW NORMAL THE REST
OF THE MONTH. ODDS ARE VERY HIGH THIS WILL BE THE COOLEST MARCH AT
GRI /AND THE REST OF THE FCST AREA/ SINCE 2002. 12Z/15 NAEFS
PROBABILITIES FOR BELOW NORMAL TEMPS ARE 70-80 PERCENT FOR MAR
23-30TH.
&&
.AVIATION...(FOR THE 06Z TAF THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1219 AM CDT SAT MAR 16 2013
SURFACE HIGH PRESSURE WILL BUILD SOUTH FM THE DAKOTAS TODAY
BEHIND THE COLD FRONT WHICH PASSED KGRI FRIDAY EVENING. STRATUS
WITH LIFR CIGS HAVE REACHED NORTHEAST NEBRASKA WITH FCST MODELS
SUGGESTING THESE LOW CLOUDS WILL BE ON THE PERIPHERY OF KGRI EARLY
SATURDAY MORNING AND WILL MONITOR TRENDS OF THIS...AND HAVE
INCLUDED A SCT IFR DECK FOR A FEW HOURS. CLOUDS WILL THICKEN ON
SATURDAY WITH INCREASING LIFT AS AN UPPER JET STREAK AND MID LEVEL
SHORTWAVE TROUGH CROSS THE PLAINS WITH SOME MVFR CIGS FORECAST
TOWARDS THE LATTER TAF HOURS. PCPN CHCS ARE NOT OUT OF THE
QUESTION BUT BETTER CHCS FOR THIS ARRIVE JUST BEYOND THE TAF
PERIOD.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...FAY
LONG TERM...HALBLAUB
AVIATION...FAY
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
613 PM EDT SAT MAR 16 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER PENNSYLVANIA THIS AFTERNOON WILL MOVE
QUICKLY EAST AND BRING AN END TO THE LIGHT SNOW THERE. BEHIND THE
LOW...HIGH PRESSURE WILL BUILD INTO THE AREA BRINGING DRIER AIR
AND JUST A FEW LIGHT SNOW SHOWERS AND FLURRIES. THE NEXT WEATHER
MAKER FOR THE AREA WILL BE A COMPLEX LOW PRESSURE SYSTEM OVER THE
GREAT LAKES AND MID ATLANTIC COAST MONDAY AND TUESDAY. THIS SYSTEM
WILL BRING SNOW OR MIXED PRECIPITATION TO THE AREA BEGINING LATE
MONDAY AND CONTINUING INTO TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
610 PM UPDATE...
LIGHT SNOW SHOWERS ARE PROVING TO BE STUBBORN HEADING INTO THE
EVENING HOURS. AFTER CHECKING THE LATEST RAP FIELDS, DECIDED TO
KEEP CHC POPS AROUND FOR A FEW EXTRA HOURS THIS EVENING. GRIDS
LOOK TO BE IN GOOD SHAPE, SO JUST A MINOR UPDATE.
3 PM UPDATE...
BACK EDGE OF THE LGT SNOW MVG RAPIDLY ACROSS CNTRL PA ATTM
AND WILL BRING AN END TO THE SNOW QUICKLY THIS AFTN. HWVR...CRNTS
UPSTREAM SHOW PLENTY OF CLDS AND LL MOISTURE HANGING BACK ALONG
THE FNTL BNDRY. SO...DONT XPCT RAPID CLRG THIS EVE...AND A FEW LGT
FLURRIES COULD LINGER THRU THE NGT. FB RPTS HAVE BEEN ANYWHERE
FROM A TRACE TO TWO INCHES SO FAR...SO WITH THE BACK EDGE MVVG
RAPIDLY EAST...REALLY NO NEED FOR ANY FLAGS WITH THIS EVENT. TEMPS
THIS EVE WILL DROP INTO THE MID TEENS OR LWR IN MANY PLACES WITH
CAA BHD THE LOW. MODEL GUID IN GOOD AGREEMENT ON MINS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
SCNDRY TROF/COLD FNT PASSES EARLY SUN MRNG AND MAY BRING SOME LGT
SNOW SHWRS TO THE NRN ZONES. MUCH DRIER AIR BHD THIS TROF SHD
ALLOW FOR GRADUAL CLRG SUN AFTN...WITH LIMITED LAKE CLDS AND
FLURRIES DUE TO THE VERY DRY AIR AND WEAK INSTABILITY OFF THE COLD
LAKE.
1028MB HIGH SLIDES SLOWLY EAST INTO NEW ENG BY EARLY MON. THIS
WILL PROVIDE THE COLD AIR AND BAROCLINIC ZONE THAT HELP DEEPENTHE
SCNDRY LOW THAT DVLPS LATE MON. OLD LOW MVES WELL WEST INTO THE
WRN LAKES...BUT WITH THIS BLOCKING HI...COLD AIR WILL BE SLOW TO
LEAVE AND WILL BE REENFORCED BY THE DVLPG CSTL LOW. THIS WILL
ALLOW SNOW TO BRK OUT FROM WEST TO EAST LATE MON AND CONT INTO
EARLY TUE. INITIAL BURST OF WAA SNOW COULD BE MODERATELY HEAVY MON
EVE. NAM HAS NOW MVD INTO THE EURO/S CAMP AND KEEPS THE AREA
COLDER THRU THE EVENT. MODEL FCST PROFILES GNRLY SUPPORT ALL SNOW
NORTH OF THE NY/PA BRDR AND EAST OF I81. TO THE SOUTH AND
WEST...WRM LAYR SHD ALLOW A CHG TO FRZG RAIN...WITH THE COLD AIR
DAMMING...DOES NOT LOOK LIKE TEMOPS WILL GET ABC FRZG...EVEN OVER
NE PA...THRU 12Z TUE.
LOW WILL MVE RAPIDLY EAST SO THE CHANCE FOR WRAP ARND SNOW FROM
THE CSTL TUE WILL BE LIMITED. ATTM...SNOWFALL AND ANY ICE AMTS
LOOK TO BE PRETTY SOLIDLY IN THE ADVISORY CATEGORY WO WILL NOT BE
ISSUING ANY FLAGS AND JUST CONT THE MENTION IN THE HWO.
GNRLY FLWD THE COLDER NAM GUID FOR THE GRIDS AS THE GFS BASED MAV
SEEMED TOO WARM.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
2 PM SAT UPDATE...
FOLLOWED WPC GUIDANCE. COLDER THAN NORMAL WITH MORE SNOW SHOWERS.
MODELS ARE SIMILAR. A NOREASTER MOVES NE INTO EASTERN NEW ENGLAND
TUESDAY NIGHT BUT A LARGE UPPER LEVEL LOW REMAINS OVER THE
NORTHEAST US AT LEAST THROUGH FRIDAY. THIS TROF KEEPS THE BIG
STORMS TO THE S0UTH BUT WILL KEEP COLD AIR OVER THE AREA. IT WILL
BE COLD ENOUGH FOR LAKE ENHANCEMENT. SLOW WARMING LATE IN THE
WEEK.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
130 PM UPDATE...
STEADY SNOW IS STAYING IN PA. KAVP WILL HAVE IFR CONDITIONS AND
ALTERNATE MINIMUMS THIS AFTN. IT MAY FALL BRIEFLY TO A QUARTER
MILE AGAIN. THE CONDITIONS WILL IMPROVE AFTER 20Z BUT IFR VSBYS
STILL POSSIBLE UNTIL 23Z. BACK TO VFR THERE AROUND 3Z.
IN NY HIGH MVFR AND VFR CONDITIONS. SOME PATCHY LIGHT SNOW CAUSING
THE MVFR. VSBY MAY BRIEFLY FALL TO IFR UP TO 2Z. AS THE LOW LEVEL
FLOW SHIFTS TO N THEN NW LATE AFTN TO EVE SNOW SHOWERS WILL BE
ENHANCED BY SOME LAKE MOISTURE.
COLDER AIR MOVING IN TONIGHT COMBINED WITH AN UPPER LEVEL SHORT
WAVE WILL BRING SOME LAKE EFFECT SNOW SHOWERS LATE TONIGHT INTO
SUNDAY MORNING. SOME MVFR CONDITIONS AND MAYBE IFR. DRIER AIR
COMES IN MIDDAY AHEAD OF A SFC HIGH SHUTTING THE LES DOWN.
LIGHT AND VARIABLE WINDS THIS AFTERNOON WILL BECOME NW AT 5 TO 10
KTS TONIGHT INTO SUNDAY MORN.
.OUTLOOK...
SUN AFTN TO MON MORN...MAINLY VFR.
MIDDAY MON TO TUE PM...MVFR/IFR RESTRICTIONS LIKELY...IN MIXED
PRECIP.
TUE NGT TO THU...MVFR/VFR WITH SCT SNOW SHWRS...MOSTLY IN NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...TAC
AREA FORECAST DISCUSSION
NWS BUFFALO NY
728 AM EDT SAT MAR 16 2013
.SYNOPSIS...
LOW PRESSURE PASSING TO THE SOUTH WILL BRING ANOTHER ROUND OF LIGHT
SNOW TODAY...WITH ACCUMULATING SNOW MAINLY IN THE SOUTHERN TIER.
HIGH PRESSURE WILL BUILD ACROSS THE REGION ON SUNDAY...WITH FAIR
WEATHER BUT CHILLY TEMPERATURES. A STRONGER SYSTEM WILL BRING SOME
RAIN OR SNOW TO THE REGION THE FIRST HALF OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A WEAK WAVE OF LOW PRESSURE WILL TRACK ALONG A STATIONARY FRONTAL
BOUNDARY WHICH IS STALLED ACROSS OHIO AND PENNSYLVANIA. 00Z MODEL
GUIDANCE AND THE HRRR HAVE TRENDED A TAD NORTH IN CONSENSUS QPF
FIELDS...AND THIS TREND APPEARS TO BE SUPPORTED BY RADAR TRENDS.
AT DAYBREAK...RADAR SHOWS A BAND OF SNOW ACROSS WESTERN PORTIONS
OF THE SOUTHERN TIER. THIS IS LIKELY ASSOCIATED WITH WARM AIR
ADVECTION IN THE MID-LEVELS WHICH IS POSITIONED JUST NORTH OF THE
FRONTAL BOUNDARY. ACROSS MICHIGAN IS A LARGER AREA OF LIGHT
PRECIPITATION. IT IS THIS SECOND AREA WHICH WILL BRING A BRIEF
PERIOD OF LIGHT SNOW TO THE REMAINDER OF THE REGION MID-MORNING
THROUGH THIS AFTERNOON. LITTLE IF ANY ACCUMULATION IN AND NORTH OF
THE BUFFALO/ROCHESTER METRO AREAS.
ACROSS WESTERN PORTIONS OF THE SOUTHERN TIER...THE MIX OF WEAK
WARM AIR ADVECTION AND A WEAK UPPER LEVEL SHORTWAVE WILL MAINTAIN
MODEST LIFT...WITH ACCUMULATIONS 1 TO 2 INCHES.
THE WEAK LOW WILL EXIT TO THE SOUTHEAST LATE THIS AFTERNOON...WHICH
WILL BRING A RETURN TO FAIR WEATHER DURING THE EVENING HOURS. SUBTLE
DOWNWARD VERTICAL MOTION BEHIND THE EXITING SYSTEM MAY BE ENOUGH FOR
SKIES TO CLEAR OUT FOR A PERIOD THIS EVENING. AFTER THIS A FAIRLY
VIGOROUS BUT MOISTURE STARVED UPPER LEVEL TROF WILL CLIP NORTHERN
NEW YORK. WITH 850MB TEMPERATURES DOWN TO -16C...AND A LIGHT FLOW ON
THE LAKE...THIS SHORTWAVE MAY TAP INTO SOME LIMITED LAKE MOISTURE IN
AN OTHERWISE DRY AIR MASS.
OTHERWISE...TEMPERATURES WILL CONTINUE TO RUN BELOW NORMAL. FAIRLY
EXTENSIVE CLOUD COVER SHOULD KEEP TEMPERATURES FROM RISING ABOVE
FREEZING TODAY. THEN LOWS TONIGHT ARE EXPECTED TO BE IN THE
TEENS...BUT ANY EXTENDED PERIODS OF CLEARING MAY ALLOW SOME
LOCATIONS TO DROP A BIT COOLER.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY AN AREA OF HIGH PRESSURE OVER THE CENTRAL GREAT LAKES WILL
PUSH EASTWARD TOWARDS THE EASTERN GREAT LAKES. TEMPERATURES ALOFT AT
850 HPA WILL START THE DAY -12 TO -18C ACROSS THE REGION...RESULTING
IN A COLD START TO SUNDAY MORNING AT THE SURFACE. THESE
TEMPERATURES ALOFT WILL WARM SOME THROUGH THE DAY...AND THIS
COMBINED WITH DRIER AIR AND ARRIVAL OF THE SURFACE HIGH PRESSURE
WILL END ANY LINGERING LIGHT LAKE EFFECT SNOW SHOWERS SOUTHEAST OF
LAKE ONTARIO SUNDAY MORNING. AFTERNOON HIGHS WILL CLIMB INTO THE
UPPER 20S AND LOW 30S SOUTH OF LAKE ONTARIO...WHILE THE NORTH
COUNTRY REMAINS IN THE MID 20S.
ON SUNDAY NIGHT THE SURFACE HIGH PRESSURE WILL CREST ACROSS THE
REGION. THIS WILL PROMOTE CLEAR SKIES AND WITH THE LIGHT WINDS
SURFACE TEMPERATURES WILL QUICKLY FALL AT NIGHT. AGAIN TEMPERATURES
WILL DROP TO BELOW NORMAL...WITH LOW 20S AND TEENS SOUTH OF LAKE
ONTARIO AND SINGLE DIGITS ACROSS THE NORTH COUNTRY WHERE THE DEEPER
POOL OF COLDER AIR WITH THE SURFACE HIGH PRESSURE WILL BE LOCATED.
MONDAY ATTENTION WILL TURN TO THE WEST AND THE APPROACHING COMPLEX
STORM SYSTEM. ALOFT A RIDGE OF HIGH PRESSURE WILL BE EXTENDED OVER
THE EAST COAST AND BACK TOWARDS CENTRAL ONTARIO CANADA. A WEAK
SHORTWAVE EJECTING FROM THE DESERT SOUTHWEST WILL BE RIDING THROUGH
THE RIDGE. A MORE POTENT PACIFIC SHORTWAVE AND ITS ASSOCIATED COLD
POOL WILL BE CARVING AN UPPER LEVEL TROUGH OVER THE CENTRAL PLAINS.
AT THE SURFACE THIS SOUTHWEST SHORTWAVE WILL DRIVE A SURFACE LOW
ACROSS THE OHIO VALLEY WITH WARM AIR ADVECTING NORTHWARD AHEAD OF
THIS FEATURE. THE ZERO DEGREE 850 HPA ISOTHERM WILL REACH INTO
SOUTHWESTERN NEW YORK MONDAY AND THEN INTO THE GENESEE VALLEY
THROUGH THE NIGHT. THIS LOW WILL WEAKEN AS IT NEARS WESTERN NEW YORK
MONDAY NIGHT WITH A SECONDARY SURFACE LOW FORMING LATE MONDAY NIGHT
NEAR THE JERSEY SHORE. THE PACIFIC SHORTWAVE WILL BE DRIVING A
SURFACE LOW ACROSS THE NORTHERN PLAINS WITH A COLD FRONT QUICKLY
SQUEEZING THE WARM SECTOR OF THIS SYSTEM. THIS COLD FRONT WILL
OCCLUDE AND PASS ACROSS EASTERN GREAT LAKES REGION MONDAY
NIGHT...REACHING THE GENESEE VALLEY BY TUESDAY MORNING.
WIND FLOW AHEAD OF THE OHIO VALLEY SURFACE LOW WILL PLAY A ROLE IN
SURFACE TEMPERATURES MONDAY WHICH WILL EFFECT THE SENSIBLE WEATHER
THROUGH THE DAY. A SOUTHEAST FLOW WILL DOWNSLOPE OFF THE HIGHER
HILLS SOUTH OF BUFFALO AND ROCHESTER...ALLOWING LOWER ELEVATIONS
NEAR LAKE ERIE...THE NORTHERN NIAGARA FRONTIER AND THE GENESEE
VALLEY TO WARM QUICKER THAN THE HIGHER ELEVATIONS THROUGH THE
DAY.
ISENTROPIC UPGLIDE AND MOISTURE CONVERGENCE ALONG THE WARM FRONT
WILL BRING A PERIOD OF PRECIPITATION ACROSS OUR REGION MONDAY AND
MONDAY NIGHT. A LOOK AT POINT SOUNDINGS DISPLAYS HIGH PROBABILITY OF
A WINTRY MIX ACROSS SOUTHWESTERN NEW YORK...WHILE THE BOUNDARY LAYER
OF LOWER ELEVATIONS WILL WARM ENOUGH TO LIKELY ALLOW JUST PLAIN RAIN
THROUGH THE DAY AND EVENING HOURS. ACROSS SOUTHWESTERN NEW
YORK...AND LATER THE EASTERN LAKE ONTARIO REGION SHELTERED VALLEYS
MAY REMAIN BELOW FREEZING LONGER...WITH A CHANCE FOR FREEZING RAIN.
THE LEADING EDGE OF PRECIPITATION WILL REACH THE GENESEE VALLEY AND
NORTHERN FINGER LAKES REGION LATE IN THE AFTERNOON HOURS ON
MONDAY...AND THEN THE EASTERN LAKE ONTARIO REGION MONDAY NIGHT AS
THE WARM FRONT CONTINUES TO LIFT NORTHWARD. COLDER AIR WILL REMAIN
DEEPER ACROSS THE NORTHERN FINGER LAKES AND EASTERN LAKE ONTARIO
REGION AND EXPECT MORE SNOW TO FALL BEFORE LIKELY CHANGING OVER TO
PLAIN RAIN OR WINTRY MIX THROUGH THE NIGHT TIME HOURS.
THROUGH THE DAYTIME MONDAY SNOW AND SLEET ACCUMULATIONS WILL BE
MINOR...WITH JUST AN INCH OR TWO LIKELY ACROSS THE HILLS OF
SOUTHWESTERN NEW YORK. SEVERAL INCHES OF SNOW ARE POSSIBLE LATER MONDAY
NIGHT TOWARDS THE EASTERN LAKE ONTARIO REGION ALTHOUGH STILL
UNCERTAINTY TO THE DEPTH OF THE COLD AIR WILL BRING THE UNCERTAINTY
AS TO WHEN AND IF THE SNOW CHANGES TO RAIN.
TEMPERATURES MONDAY WILL CLIMB TOWARDS 40 ACROSS LOWER ELEVATIONS
SOUTH OF LAKE ONTARIO...AND MID TO UPPER 30S FOR HIGHER ELEVATIONS.
EAST OF LAKE ONTARIO AND NORTH OF THE WARM FRONT HIGHS WILL HOLD IN
THE LOW TO MID 30S. MONDAY NIGHT TEMPERATURES SHOULD RISE A DEGREE
OR TWO ACROSS THE EASTERN LAKE ONTARIO REGION...WHILE LOWS ACROSS
WESTERN NEW YORK WILL DROP BACK INTO THE LOW TO MID 30S BEHIND THE
PASSAGE OF THE OCCLUDED FRONT.
AS THIS OCCLUDED FRONT PASSES A FEW RAIN SHOWERS CHANGING TO SNOW
SHOWERS IS POSSIBLE...ESPECIALLY ACROSS THE UPSLOPE HIGHER TERRAIN
SOUTH OF BUFFALO.
A GUSTY SOUTHWEST TO WESTERLY BREEZE WILL INCREASE LATER THROUGH THE
NIGHT MONDAY NIGHT COINCIDING WITH THE COLD AIR ADVECTION ALOFT.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
UNSEASONABLY COOL TEMPERATURES AND UNSETTLED WEATHER WILL BE THE
RULE DURING THIS PERIOD AS A DEEPENING UPPER LEVEL TROUGH CLOSES OFF
OVER THE LOWER GREAT LAKES AND NEW ENGLAND.
AT THE SURFACE...THE ASSOCIATED SURFACE LOW WILL DRAG THE
AFOREMENTIONED OCCLUDED FRONT EAST ACROSS THE CWA TUESDAY MORNING.
RAIN SHOWERS IN THE RELATIVELY MILD AIR AHEAD OF THE FRONT WILL
CHANGE TO SNOW AS COLDER AIR ADVECTS EAST ACROSS THE AREA DURING THE
AFTERNOON. THE SNOW SHOULD NOT BE TOO HEAVY SINCE A DRY SLOT IS
EXPECTED TO BE IN PLACE BEHIND THE FRONT WHEN THE COLDER AIR
ARRIVES.
AS THE COLDER AIR DEEPENS ON TUESDAY...WEST TO SOUTHWEST WILL PICK
UP...BUT THE LATEST GFS MOMENTUM TRANSFER SCHEMES SUGGESTS THAT
WINDS MAY STAY BELOW ADVISORY CRITERIA.
TUESDAY NIGHT AND WEDNESDAY...THE INITIAL LOW IS FORECAST TO MERGE
WITH A SECOND LOW THAT WILL BE MOVING UP THE MAINE COAST AND INTO
CANADIAN MARITIMES. COLDER AIR AND DEEPER MOISTURE WRAPPING AROUND
THIS LOW WILL BRING A GOOD CHANCE FOR WIDESPREAD SNOW SHOWERS AND
SOME LAKE EFFECT SNOW TUESDAY NIGHT THROUGH THURSDAY.
EXPECT QUIET CONDITIONS FRIDAY AS THE LOW SLIDES OFF THE CANADIAN
MARITIMES COAST AND A RIDGE OF HIGH PRESSURE OVER CENTRAL CANADA
BUILDS SOUTH ACROSS THE LOWER LAKES.
&&
.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
A WAVE OF LOW PRESSURE WILL TRACK ALONG A STALLED FRONTAL BOUNDARY
WHICH IS SOUTH OF THE REGION. IT SHOULD BE FAR ENOUGH SOUTH TO
HAVE ONLY A MINIMAL IMPACT ON MOST OF OUR TAF SITES...LIKELY
RESULTING IN VERY LIGHT SNOW AND PERHAPS A PERIOD OF MVFR
CONDITIONS AT BUF/IAG/ROC. JHW IS CLOSER TO THE LOW...AND SHOULD
GET A PERIOD OF LIGHT SNOW. AT JHW...EXPECT A PERIOD OF IFR
CONDITIONS...WITH VSBY AVERAGING AROUND 2SM THIS MORNING.
CONDITIONS SHOULD IMPROVE LATE AFTERNOON...AS DRIER AIR BUILDS
BEHIND THE DISTURBANCE. THIS SHOULD BRING FAIRLY WIDESPREAD VFR
CONDITIONS THIS EVENING. COOLER TEMPERATURES ALOFT AND A LIGHT NW
FLOW WILL LIKELY ENHANCE CLOUD COVER LATE TONIGHT...WITH THE
POSSIBILITY OF MVFR CIGS AT SOME LOCATIONS. IF SKIES STAY CLEAR
LONG ENOUGH...THERE IS ALSO A POTENTIAL FOR FOG AT JHW.
OUTLOOK...
SUNDAY...VFR.
MONDAY AND TUESDAY...IFR/MVFR. RAIN OR SNOW LIKELY.
WEDNESDAY...MVFR TO IFR IN LAKE EFFECT SNOW SHOWERS.
&&
.MARINE...
THINGS SHOULD BE RELATIVELY QUIET ON THE WATERS THROUGH MONDAY AS A
WEAK SYSTEM PASSING TO THE SOUTH IS FOLLOWED BY HIGH PRESSURE. A
DEVELOPING NORTHEAST FLOW TODAY SHOULD RESULT IN WAVES JUST SHY OF
SMALL CRAFT CRITERIA ON LAKE ERIE WEST OF DUNKIRK.
WINDS TURN TO SOUTHEASTERLY AND INCREASE IN SPEED MONDAY
NIGHT...THEN SHIFT TO THE SOUTHWEST ON TUESDAY AS LOW PRESSURE
PASSES TO THE NORTH OF THE REGION. SMALL CRAFT ADVISORIES ARE ALMOST
CERTAIN AND GALES ARE A POSSIBILITY FOR A PERIOD DURING TUESDAY
NIGHT AND WEDNESDAY.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...TJP
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
402 AM EDT SAT MAR 16 2013
.SYNOPSIS...
LOW PRESSURE PASSING TO THE SOUTH WILL BRING ANOTHER ROUND OF LIGHT
SNOW TODAY...WITH ACCUMULATING SNOW MAINLY IN THE SOUTHERN TIER.
HIGH PRESSURE WILL BUILD ACROSS THE REGION ON SUNDAY...WITH FAIR
WEATHER BUT CHILLY TEMPERATURES. A STRONGER SYSTEM WILL BRING SOME
RAIN OR SNOW TO THE REGION THE FIRST HALF OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A WEAK WAVE OF LOW PRESSURE WILL TRACK ALONG A STATIONARY FRONTAL
BOUNDARY WHICH IS STALLED ACROSS OHIO AND PENNSYLVANIA. 00Z MODEL
GUIDANCE AND THE HRRR HAVE TRENDED A TAD NORTH IN CONSENSUS QPF
FIELDS...AND THIS TREND APPEARS TO BE SUPPORTED BY RADAR TRENDS.
BECAUSE OF THIS...WILL INCREASE POPS TO CATEGORICAL IN THE SOUTHERN
TIER. DESPITE THE HIGH POPS...THE MIX OF WEAK WARM AIR ADVECTION AND
A WEAK UPPER LEVEL SHORTWAVE WILL ONLY GENERATE MODEST LIFT AND
GENERALLY LIGHT SNOW...WITH ACCUMULATIONS 1 TO 2 INCHES IN THE
SOUTHERN TIER. JUST NORTH OF THIS...IT WILL BE TOO FAR NORTH TO HAVE
ANY CONTRIBUTION FROM THE FRONT...WITH THE SHORTWAVE LIKELY TO
BRING SOME SNOW SHOWERS OR FLURRIES...WITH LITTLE IF ANY
ACCUMULATION IN AND NORTH OF THE BUFFALO/ROCHESTER METRO AREAS.
THE WEAK LOW WILL EXIT TO THE SOUTHEAST LATE THIS AFTERNOON...WHICH
WILL BRING A RETURN TO FAIR WEATHER DURING THE EVENING HOURS. SUBTLE
DOWNWARD VERTICAL MOTION BEHIND THE EXITING SYSTEM MAY BE ENOUGH FOR
SKIES TO CLEAR OUT FOR A PERIOD THIS EVENING. AFTER THIS A FAIRLY
VIGOROUS BUT MOISTURE STARVED UPPER LEVEL TROF WILL CLIP NORTHERN
NEW YORK. WITH 850MB TEMPERATURES DOWN TO -16C...AND A LIGHT FLOW ON
THE LAKE...THIS SHORTWAVE MAY TAP INTO SOME LIMITED LAKE MOISTURE IN
AN OTHERWISE DRY AIR MASS.
OTHERWISE...TEMPERATURES WILL CONTINUE TO RUN BELOW NORMAL. FAIRLY
EXTENSIVE CLOUD COVER SHOULD KEEP TEMPERATURES FROM RISING ABOVE
FREEZING TODAY. THEN LOWS TONIGHT ARE EXPECTED TO BE IN THE
TEENS...BUT ANY EXTENDED PERIODS OF CLEARING MAY ALLOW SOME
LOCATIONS TO DROP A BIT COOLER.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY AN AREA OF HIGH PRESSURE OVER THE CENTRAL GREAT LAKES WILL
PUSH EASTWARD TOWARDS THE EASTERN GREAT LAKES. TEMPERATURES ALOFT AT
850 HPA WILL START THE DAY -12 TO -18C ACROSS THE REGION...RESULTING
IN A COLD START TO SUNDAY MORNING AT THE SURFACE. THESE
TEMPERATURES ALOFT WILL WARM SOME THROUGH THE DAY...AND THIS
COMBINED WITH DRIER AIR AND ARRIVAL OF THE SURFACE HIGH PRESSURE
WILL END ANY LINGERING LIGHT LAKE EFFECT SNOW SHOWERS SOUTHEAST OF
LAKE ONTARIO SUNDAY MORNING. AFTERNOON HIGHS WILL CLIMB INTO THE
UPPER 20S AND LOW 30S SOUTH OF LAKE ONTARIO...WHILE THE NORTH
COUNTRY REMAINS IN THE MID 20S.
ON SUNDAY NIGHT THE SURFACE HIGH PRESSURE WILL CREST ACROSS THE
REGION. THIS WILL PROMOTE CLEAR SKIES AND WITH THE LIGHT WINDS
SURFACE TEMPERATURES WILL QUICKLY FALL AT NIGHT. AGAIN TEMPERATURES
WILL DROP TO BELOW NORMAL...WITH LOW 20S AND TEENS SOUTH OF LAKE
ONTARIO AND SINGLE DIGITS ACROSS THE NORTH COUNTRY WHERE THE DEEPER
POOL OF COLDER AIR WITH THE SURFACE HIGH PRESSURE WILL BE LOCATED.
MONDAY ATTENTION WILL TURN TO THE WEST AND THE APPROACHING COMPLEX
STORM SYSTEM. ALOFT A RIDGE OF HIGH PRESSURE WILL BE EXTENDED OVER
THE EAST COAST AND BACK TOWARDS CENTRAL ONTARIO CANADA. A WEAK
SHORTWAVE EJECTING FROM THE DESERT SOUTHWEST WILL BE RIDING THROUGH
THE RIDGE. A MORE POTENT PACIFIC SHORTWAVE AND ITS ASSOCIATED COLD
POOL WILL BE CARVING AN UPPER LEVEL TROUGH OVER THE CENTRAL PLAINS.
AT THE SURFACE THIS SOUTHWEST SHORTWAVE WILL DRIVE A SURFACE LOW
ACROSS THE OHIO VALLEY WITH WARM AIR ADVECTING NORTHWARD AHEAD OF
THIS FEATURE. THE ZERO DEGREE 850 HPA ISOTHERM WILL REACH INTO
SOUTHWESTERN NEW YORK MONDAY AND THEN INTO THE GENESEE VALLEY
THROUGH THE NIGHT. THIS LOW WILL WEAKEN AS IT NEARS WESTERN NEW YORK
MONDAY NIGHT WITH A SECONDARY SURFACE LOW FORMING LATE MONDAY NIGHT
NEAR THE JERSEY SHORE. THE PACIFIC SHORTWAVE WILL BE DRIVING A
SURFACE LOW ACROSS THE NORTHERN PLAINS WITH A COLD FRONT QUICKLY
SQUEEZING THE WARM SECTOR OF THIS SYSTEM. THIS COLD FRONT WILL
OCCLUDE AND PASS ACROSS EASTERN GREAT LAKES REGION MONDAY
NIGHT...REACHING THE GENESEE VALLEY BY TUESDAY MORNING.
WIND FLOW AHEAD OF THE OHIO VALLEY SURFACE LOW WILL PLAY A ROLE IN
SURFACE TEMPERATURES MONDAY WHICH WILL EFFECT THE SENSIBLE WEATHER
THROUGH THE DAY. A SOUTHEAST FLOW WILL DOWNSLOPE OFF THE HIGHER
HILLS SOUTH OF BUFFALO AND ROCHESTER...ALLOWING LOWER ELEVATIONS
NEAR LAKE ERIE...THE NORTHERN NIAGARA FRONTIER AND THE GENESEE
VALLEY TO WARM QUICKER THAN THE HIGHER ELEVATIONS THROUGH THE
DAY.
ISENTROPIC UPGLIDE AND MOISTURE CONVERGENCE ALONG THE WARM FRONT
WILL BRING A PERIOD OF PRECIPITATION ACROSS OUR REGION MONDAY AND
MONDAY NIGHT. A LOOK AT POINT SOUNDINGS DISPLAYS HIGH PROBABILITY OF
A WINTRY MIX ACROSS SOUTHWESTERN NEW YORK...WHILE THE BOUNDARY LAYER
OF LOWER ELEVATIONS WILL WARM ENOUGH TO LIKELY ALLOW JUST PLAIN RAIN
THROUGH THE DAY AND EVENING HOURS. ACROSS SOUTHWESTERN NEW
YORK...AND LATER THE EASTERN LAKE ONTARIO REGION SHELTERED VALLEYS
MAY REMAIN BELOW FREEZING LONGER...WITH A CHANCE FOR FREEZING RAIN.
THE LEADING EDGE OF PRECIPITATION WILL REACH THE GENESEE VALLEY AND
NORTHERN FINGER LAKES REGION LATE IN THE AFTERNOON HOURS ON
MONDAY...AND THEN THE EASTERN LAKE ONTARIO REGION MONDAY NIGHT AS
THE WARM FRONT CONTINUES TO LIFT NORTHWARD. COLDER AIR WILL REMAIN
DEEPER ACROSS THE NORTHERN FINGER LAKES AND EASTERN LAKE ONTARIO
REGION AND EXPECT MORE SNOW TO FALL BEFORE LIKELY CHANGING OVER TO
PLAIN RAIN OR WINTRY MIX THROUGH THE NIGHT TIME HOURS.
THROUGH THE DAYTIME MONDAY SNOW AND SLEET ACCUMULATIONS WILL BE
MINOR...WITH JUST AN INCH OR TWO LIKELY ACROSS THE HILLS OF
SOUTHWESTERN NEW YORK. SEVERAL INCHES OF SNOW ARE POSSIBLE LATER MONDAY
NIGHT TOWARDS THE EASTERN LAKE ONTARIO REGION ALTHOUGH STILL
UNCERTAINTY TO THE DEPTH OF THE COLD AIR WILL BRING THE UNCERTAINTY
AS TO WHEN AND IF THE SNOW CHANGES TO RAIN.
TEMPERATURES MONDAY WILL CLIMB TOWARDS 40 ACROSS LOWER ELEVATIONS
SOUTH OF LAKE ONTARIO...AND MID TO UPPER 30S FOR HIGHER ELEVATIONS.
EAST OF LAKE ONTARIO AND NORTH OF THE WARM FRONT HIGHS WILL HOLD IN
THE LOW TO MID 30S. MONDAY NIGHT TEMPERATURES SHOULD RISE A DEGREE
OR TWO ACROSS THE EASTERN LAKE ONTARIO REGION...WHILE LOWS ACROSS
WESTERN NEW YORK WILL DROP BACK INTO THE LOW TO MID 30S BEHIND THE
PASSAGE OF THE OCCLUDED FRONT.
AS THIS OCCLUDED FRONT PASSES A FEW RAIN SHOWERS CHANGING TO SNOW
SHOWERS IS POSSIBLE...ESPECIALLY ACROSS THE UPSLOPE HIGHER TERRAIN
SOUTH OF BUFFALO.
A GUSTY SOUTHWEST TO WESTERLY BREEZE WILL INCREASE LATER THROUGH THE
NIGHT MONDAY NIGHT COINCIDING WITH THE COLD AIR ADVECTION ALOFT.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
UNSEASONABLY COOL TEMPERATURES AND UNSETTLED WEATHER WILL BE THE
RULE DURING THIS PERIOD AS A DEEPENING UPPER LEVEL TROUGH CLOSES OFF
OVER THE LOWER GREAT LAKES AND NEW ENGLAND.
AT THE SURFACE...THE ASSOCIATED SURFACE LOW WILL DRAG THE
AFOREMENTIONED OCCLUDED FRONT EAST ACROSS THE CWA TUESDAY MORNING.
RAIN SHOWERS IN THE RELATIVELY MILD AIR AHEAD OF THE FRONT WILL
CHANGE TO SNOW AS COLDER AIR ADVECTS EAST ACROSS THE AREA DURING THE
AFTERNOON. THE SNOW SHOULD NOT BE TOO HEAVY SINCE A DRY SLOT IS
EXPECTED TO BE IN PLACE BEHIND THE FRONT WHEN THE COLDER AIR
ARRIVES.
AS THE COLDER AIR DEEPENS ON TUESDAY...WEST TO SOUTHWEST WILL PICK
UP...BUT THE LATEST GFS MOMENTUM TRANSFER SCHEMES SUGGESTS THAT
WINDS MAY STAY BELOW ADVISORY CRITERIA.
TUESDAY NIGHT AND WEDNESDAY...THE INITIAL LOW IS FORECAST TO MERGE
WITH A SECOND LOW THAT WILL BE MOVING UP THE MAINE COAST AND INTO
CANADIAN MARITIMES. COLDER AIR AND DEEPER MOISTURE WRAPPING AROUND
THIS LOW WILL BRING A GOOD CHANCE FOR WIDESPREAD SNOW SHOWERS AND
SOME LAKE EFFECT SNOW TUESDAY NIGHT THROUGH THURSDAY.
EXPECT QUIET CONDITIONS FRIDAY AS THE LOW SLIDES OFF THE CANADIAN
MARITIMES COAST AND A RIDGE OF HIGH PRESSURE OVER CENTRAL CANADA
BUILDS SOUTH ACROSS THE LOWER LAKES.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
A WAVE OF LOW PRESSURE WILL TRACK ALONG A STALLED FRONTAL BOUNDARY
WHICH IS SOUTH OF THE REGION. THIS WAVE WILL PASS TO THE SOUTH BETWEEN
12Z AND 21Z. IT SHOULD BE FAR ENOUGH SOUTH TO HAVE ONLY A MINIMAL
IMPACT ON MOST OF OUR TAF SITES...LIKELY RESULTING IN VERY LIGHT
SNOW AND PERHAPS A PERIOD OF MVFR CONDITIONS AT BUF/IAG/ROC. JHW IS
CLOSER TO THE LOW...AND SHOULD GET A PERIOD OF LIGHT SNOW. EXPECT
LOWERING VSBY AND CIGS TO RESULT IN A PERIOD OF IFR
CONDITIONS THIS MORNING.
CONDITIONS SHOULD IMPROVE LATE AFTERNOON...AS DRIER AIR BUILDS
BEHIND THE DISTURBANCE. THIS SHOULD BRING FAIRLY WIDESPREAD VFR
CONDITIONS THIS EVENING. IF SKIES STAY CLEAR LONG ENOUGH...THERE IS
A POTENTIAL FOR FOG TO DEVELOP AT JHW LATE TONIGHT.
OUTLOOK...
SUNDAY...VFR.
MONDAY AND TUESDAY...IFR/MVFR. RAIN OR SNOW LIKELY.
WEDNESDAY...MVFR TO IFR IN LAKE EFFECT SNOW SHOWERS.
&&
.MARINE...
THINGS SHOULD BE RELATIVELY QUIET ON THE WATERS THROUGH MONDAY AS A
WEAK SYSTEM PASSING TO THE SOUTH IS FOLLOWED BY HIGH PRESSURE. A
DEVELOPING NORTHEAST FLOW TODAY SHOULD RESULT IN WAVES JUST SHY OF
SMALL CRAFT CRITERIA ON LAKE ERIE WEST OF DUNKIRK.
WINDS TURN TO SOUTHEASTERLY AND INCREASE IN SPEED MONDAY
NIGHT...THEN SHIFT TO THE SOUTHWEST ON TUESDAY AS LOW PRESSURE
PASSES TO THE NORTH OF THE REGION. SMALL CRAFT ADVISORIES ARE ALMOST
CERTAIN AND GALES ARE A POSSIBILITY FOR A PERIOD DURING TUESDAY
NIGHT AND WEDNESDAY.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...TJP
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
243 AM EDT SAT MAR 16 2013
.SYNOPSIS...
A COLD FRONT WILL SETTLE SOUTH THROUGH NORTH CAROLINA TONIGHT
THEN STALL OVER SOUTH CAROLINA SUNDAY INTO MONDAY. CHILLY HIGH
PRESSURE WILL BUILD SOUTHWARD FROM NEW ENGLAND INTO OUR REGION
SUNDAY INTO MONDAY. A COLD FRONT WILL SURGE EAST THROUGH THE REGION
TUESDAY MORNING.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 940 PM FRIDAY...
DISTURBED NORTHWESTERLY FLOW CONTINUES ALOFT...WHILE A COLD FRONT
DRAPED ACROSS THE MIDWEST IS SLOWLY SINKING SOUTH ACROSS THE OH
VALLEY REGION. OROGRAPHICALLY ENHANCED CIRRUS HAS DIMINISHED SINCE
EARLY IN THE AFTERNOON...AND CIRRUS IS MORE PATCHY ACROSS MUCH OF
THE REGION. WITH THIS TEMPORARY CLEARING...TEMPS HAVE FALLEN A BIT
MORE QUICKLY THAN FORECAST...BUT A LIGHT SOUTHWESTERLY WIND WILL
CONTINUE...SO WILL ONLY MAKE A FEW MINOR ADJUSTMENT TO TEMPS...WITH
MID 40S NORTHEAST TO UPPER 40S SOUTHWEST. TO OUR WEST... STRONG
WARM ADVECTION IS UNDERWAY ACROSS THE MID MS RIVER VALLEY REGION AND
IT FEEDING AN AREA OF SHOWERS MOVING ALONG THE AFOREMENTIONED COLD
FRONT...APPROACHING EASTERN KENTUCKY AND WEST VIRGINIA. EARLIER
RUNS OF THE HRRR WERE SHOWING SHOWERS SPREADING INTO CENTRAL NC AS
THE LOW LEVEL THETA E RIDGE NOSES EASTWARD. CONSIDERED ADDING A
SLIGHT CHANCE POP NEAR THE VA BORDER OVERNIGHT...BUT THE HRRR (AND
OTHER CAMS) APPEARS OVERDONE...AND ANY SHOWERS SEEM MORE LIKELY
AFTER SUNRISE WITH ADDITIONAL HEATING/LOW LEVEL MOISTURE AND BETTER
INSTABILITY. -BLS
SATURDAY
AFOREMENTIONED S/W AND ASSOCIATED SURFACE LOW WILL TRACK ACROSS
CENTRAL AND SOUTHERN VA ON SATURDAY. THIS COUPLED WITH SOME WEAK
INSTABILITY WILL SUPPORT AND AREA OF SHOWERS AND STORMS ACROSS
PORTIONS OF VA... INVOF THE STALLED FRONT (BECOMING A COLD FRONT
SATURDAY NIGHT AS THE SURFACE LOW MOVES TO THE EAST OF THE AREA).
SOME OF THESE SHOWERS AND STORMS MAY MAKE IT INTO NORTHERN PORTIONS
OF CENTRAL NC... NEAR THE NC/VA BORDER. FOR NOW WILL CONTINUE TO
SHOW ONLY A LOW END CHANCE/SLIGHT CHANCE POPS FOR LOCATIONS NEAR THE
NC/VA BORDER. GIVEN DEEP LAYER SHEAR VALUES APPROACHING 50 KTS...
COUPLED WITH SOME WEAK INSTABILITY THINK WE STILL HAVE AT LEAST A
SMALL THREAT OF AT LEAST A STRONG STORM OR TWO NEAR THE NC/VA BORDER
TOMORROW (IF WE GET ANY STORMS THAT MAKE IT INTO OUR AREA).
HOWEVER... WITH DEWPOINTS IN THE 40S EXPECTED AND MARGINAL
INSTABILITY (WITH THE MID LEVEL CAP NOT WEAKENING UNTIL VERY LATE IN
THE DAY) THINK THE WINDOW FOR A SVR STORM OR TWO REMAINS QUITE
SMALL. GIVEN THE RATHER LOW DEWPOINTS AND DRY SUB-CLOUD LAYER EXPECT
OUR MAIN THREAT WILL BE DAMAGING WINDS... ALONG WITH POSSIBLY SOME
HAIL THANKS TO THE IMPRESSIVE SHEAR. GIVEN THE REASON FOR ONLY A
VERY SMALL AND BIT UNCERTAIN THREAT OF SVR STORMS... SPC HAS REMOVED
THE SLIGHT RISK FOR SATURDAY. THE BIGGER STORY ON SATURDAY MAY BE
THE GUSTY WINDS... WITH WIND GUSTS OF UP TO 30 TO 33 MPH POSSIBLE.
THANKS TO THE BIT FARTHER NORTHWARD PLACEMENT OF THE FRONT ON
SATURDAY... AND A BIT LESS CHANCE OF PRECIP... EXPECT HIGHS TO BE IN
THE MID TO UPPER 70S... WITH EVEN SOME TEMPS AROUND 80 POSSIBLE.
SATURDAY NIGHT AND SUNDAY...A MID-UPPER LEVEL S/W CROSSING NEW
ENGLAND WILL NUDGE A SFC COLD FRONT SWD INTO CENTRAL NC. ANY SHOWERS
OR T-STORMS ALONG THIS FEATURE WILL DIMINISH WITH TIME AS FRONT
ENCOUNTERS A SLIGHTLY DRIER AND MORE STABLE AIR MASS. SHORT TERM
MODEL GUIDANCE IN GOOD AGREEMENT...DEPICTING THE SFC BOUNDARY
STALLING ACROSS OUR SOUTHERN COUNTIES BY EARLY SUN. MIN TEMPS VARY
FROM THE LOWER 40S FAR NORTH TO THE LOWER 50S SOUTH.
A SERIES OF PERTURBATIONS IN THE WLY FLOW ALOFT WILL GRADUALLY
INCREASE MID LEVEL CONFLUENCE ACROSS NORTHERN NC/SOUTHERN VA
SUNDAY...MAINTAINING A MOISTURE AXIS OVER THIS REGION.
MEANWHILE...A S-SW FLOW WILL DEVELOP A FEW THOUSAND FT ABOVE THE
SURFACE...SETTING UP AN OVERRUNNING PRECIP EVENT. THIS SHOULD LEAD
TO AN INCREASE IN RAIN COVERAGE NORTH OF THE BOUNDARY DURING THE DAY
SUNDAY. EXTENT OF PRECIP WILL DETERMINE MAX TEMPS. IF RAIN MORE
WIDESPREAD THAN CURRENTLY EXPECTED...TEMPS IN THE TRIAD AND TRIANGLE
REGIONS MAY END UP 5-8 DEGREES COOLER THAN FORECAST.
CONVERSELY...TEMPS NEAR OR SOUTH OF THE BOUNDARY COULD BE IN THE
LOW-MID 70S...DEPENDING ON THE AMOUNT OF CLOUD COVERAGE. IF FRONT
DRIFTS INTO SC...MAX TEMPS IN FAY REGION MAY BE AS MUCH AS 5-6
DEGREES COOLER THAN FORECAST.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH 12Z TUESDAY/...
AS OF 200 AM SATURDAY...
...HIGH CONFIDENCE IN THAT COLD AIR DAMMING (CAD) WILL PREVAIL
ACROSS OUR REGION SUNDAY NIGHT THROUGH MONDAY...
THE MODELS ARE FINALLY COMING AROUND TO FORECASTING A COLD AIR
DAMMING EVENT IN OUR PIEDMONT DAMMING REGION SUNDAY NIGHT AND
MONDAY. THE MODELS ARE TYPICALLY SLOW TO CATCH ON TO CAD EVEN IN
THIS CASE WHEN THE PARENT SURFACE HIGH IS FORECAST (AS HAS BEEN FOR
SEVERAL DAYS) TO BE MORE THAN SUFFICIENT STRENGTH (1025 MB)... AND
LOCATION (PA/NY STATE)... TO DELIVER THE DRY COLD AIR INTO OUR
REGION. THE OTHER PLAYER (QPF) WHICH NEEDS TO BE IN GENERAL NEAR
0.10 TO LOCK IN THE CAD ALSO APPEARS LIKELY. THEREFORE... WITH ALL
THREE MAJOR PLAYERS EXPECTED TO BE POSITIVE... THEN WITH HIGH
CONFIDENCE CAD WILL BE FORECAST.
THE MOST DIFFICULT PART OF THE FORECAST WILL BE THE QPF ASSOCIATED
WITH THE ISENTROPIC LIFT INITIALLY WITH THE FRONT TO OUR SOUTH
SUNDAY INTO EARLY MONDAY... THEN WITH THE MAIN STORM TRACK EXPECTED
TO BE WEST OF THE MOUNTAINS MONDAY NIGHT. THE ENDING OF THE CAD WILL
LIKELY BE THE ACTUAL COLD FRONTAL PASSAGE EARLY TUESDAY FROM THE
WEST.
SENSIBLE WEATHER WILL INCLUDE: CLOUDY AND COOL SUNDAY NIGHT AND
MONDAY WITH THE LOW LEVEL NE FLOW... AND UPPER LEVEL SW FLOW.
OCCASIONAL LIGHT RAIN/DRIZZLE IN THE DAMMING REGION AND A CHANCE OF
RAIN SE. LOWS SUNDAY NIGHT 35-40 PIEDMONT DAMMING REGION... AND
40-45 SE. HIGHS MONDAY IN THE 40S WEST AND NORTH RANGING INTO THE
LOWER 50S SE. TEMPS MONDAY NIGHT WILL EITHER HOLD STEADY OR SLOWLY
RISE AS THE MAIN LOW PRESSURE LIFTS THROUGH THE TN VALLEY TOWARD NY
STATE BY 12Z/TUE. THE CAD BOUNDARY WILL TRY TO LIFT BACK NW-N... BUT
SHOULD HAVE PLENTY OF COOL STABLE AIR TO PROVIDE RESISTANCE IN THE
PIEDMONT. THIS SHOULD LEAD TO AREAS OF DENSE FOG IN THE DAMMING
REGION LATE MONDAY INTO MONDAY NIGHT. OTHERWISE... OCCASIONAL RAIN
MAINLY WEST... AND A CHANCE OF RAIN EAST. LOWS 40S TO LOWER 50S THEN
RISING... ESPECIALLY EAST TO AROUND 60.
THE QPF APPEARS THAT IT WILL BE HIGHEST IN THE DAMMING REGION AND
CLOSEST TO THE STORM TRACK TO OUR WEST FOR THIS EVENT. WE WILL
FORECAST 0.25 TO 0.50 OF AN INCH IN THE NW... AND LESS THAN 0.20 IN
THE SE.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 230 AM SATURDAY...
THE ARCTIC OSCILLATION AND THE NORTH ATLANTIC OSCILLATION HAVE BOTH
BEEN RUNNING STRONGLY NEGATIVE RECENTLY. THE RESULTANT UPPER AIR
PATTERN HAS BEEN ONE THAT HAS FEATURED THE MAIN TROUGH OVER THE
EASTERN UNITED STATES WITH COLDER THAN NORMAL TEMPERATURES. THE
FIRST TWO WEEKS OF MARCH HAVE BEEN 4-5 DEGREES COLDER THAN THE 30
YEAR STATISTICAL AVERAGE AT KGSO/KRDU/AND KFAY.
THE FORECAST FOR THE MIDDLE TO LATTER HALF OF THIS WEEKS CONTINUES
TO LOOK COLDER THAN NORMAL OVERALL. THE MAIN FLOW PATTERN IS
EXPECTED TO CONTINUE TO BE DRIVEN BY THE STRONGLY NEGATIVE AO/NAO...
WITH A DEEP TROUGH OVER THE CENTRAL AND EASTERN UNITED STATES. THIS
SHOULD LEAD TO A SIGNIFICANT PRECIPITATION EVENT FOR OUR REGION BY
FRI OR OVER THE WEEKEND.
SENSIBLE WEATHER:
TUESDAY... THE CAD WILL BE BROKEN UP AS THE MAIN COLD FRONT SURGES
EAST THROUGH THE REGION EARLY MORNING. STRONG SUBSIDENCE IN THE REAR
OF THE DEPARTING TROUGH/FRONT WILL LEAD TO CLEARING AND BREEZY
CONDITIONS. THE WNW FLOW WILL BE DOWNSLOPE DURING THE DAY ALLOWING
FOR A MILD DAY... BEFORE CAA SETS IN LATER. EXPECT SKIES TO BECOME
MOSTLY SUNNY. HIGHS GENERALLY IN THE MID 60S NORTHWEST AND 70-75
ELSEWHERE. TUESDAY NIGHT AND WEDNESDAY... MOSTLY CLEAR AND COOLER.
LOWS IN THE 30S. HIGHS WEDNESDAY IN THE MID 50S TO LOWER 60S.
THURSDAY AND FRIDAY... CHILLY. INCREASING CLOUDINESS THURSDAY NIGHT.
A CHANCE OF RAIN BY FRIDAY. LOWS THURSDAY 30-35 NW AND MID 30S SE.
HIGHS THURSDAY IN THE 50S. LOWS THURSDAY NIGHT 35-40. HIGHS FRIDAY
IN THE 40S NW AND 50S SE.
IT IS UNCLEAR AT THE MOMENT IN THE STRENGTH AND POSITION OF A
POTENTIAL CAD HIGH AGAIN FOR THIS SYSTEM. HOWEVER... IT DOES APPEAR
LIKELY THAT ANOTHER STRONG MID-UPPER TROUGH WILL OCCUPY THE MIDWEST
TO GREAT LAKES AND OUR REGION BEYOND SATURDAY. THIS WOULD BRING
ANOTHER WEEK OF MUCH BELOW NORMAL TEMPERATURES TO CENTRAL NC
PREVENTING AN EARLY WARM SPRING.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 235 AM SATURDAY...
VFR CONDITIONS WILL RULE THROUGH THE TAF PERIOD. BETWEEN HIGH
PRESSURE CENTERED OVER FLORIDA AND A LOW PRESSURE SYSTEM FORECAST TO
TRACK ACROSS THE LOWER OH VALLEY AND MIDDLE ATLANTIC REGION...VERY
BREEZY AND WARM SOUTHWESTERLY FLOW WILL DEVELOP AT THE SURFACE ONCE
THE MORNING INVERSION BREAKS AROUND 15-16Z. IN THE MEANTIME...STRONG
WINDS WITHIN SAID INVERSION -- INCLUDING 30-40 KTS FROM THE WSW AT
2000 FT -- WILL PROMOTE LOW LEVEL WIND SHEAR AT KFAY WHERE THESE
INVERSION WINDS WILL BE STRONGEST. A COLD FRONT TRAILING THE
AFOREMENTIONED LOW PRESSURE SYSTEM WILL SETTLE SOUTHWARD INTO
CENTRAL NC THIS EVENING-TONIGHT. WIDELY SCATTERED SHOWERS AND STORMS
MAY DEVELOP ALONG AND IMMEDIATELY AHEAD OF THE FRONT AND AFFECT
AREAS IN THE VICINITY OF THE VA BORDER - JUST NORTH OF CENTRAL NC
TERMINALS - BEFORE DISSIPATING SHORTLY AFTER SUNSET.
OUTLOOK: POST-FRONTAL MVFR-IFR CEILINGS WILL DEVELOP SOUTHWARD...
FROM KRWI VERY LATE TONIGHT...AND ACROSS THE REMAINDER OF CENTRAL NC
TERMINALS ON SUN. PERIODS OF DRIZZLE OR LIGHT RAIN WILL THEN BECOME
WIDESPREAD...WITH STEADY DETERIORATION TO LIFR RANGE IN MATURE COLD
AIR DAMMING SUN NIGHT. THESE CONDITIONS WILL LIKELY CONTINUE UNTIL A
COLD FRONT SWEEPS THE COLD AIR DAMMING/ADVERSE AVIATION CONDITIONS
OUT OF THE AREA LATE MON NIGHT-TUE.
&&
.FIRE WEATHER...
AS OF 236 AM SATURDAY...
SOUTHWEST WINDS SUSTAINED AT 15-20 MPH WITH FREQUENT GUSTS TO 30 MPH
ARE EXPECTED TODAY. MINIMUM RELATIVE HUMIDITY VALUES IN THE
AFTERNOON WILL BE IN THE 30-40 PERCENT RANGE MOST AREAS... REMAINING
ABOVE THE CRITICAL FIRE WEATHER THRESHOLD OF 25 PERCENT OR BELOW.
PER PREVIOUS DISCUSSION WITH THE NORTH CAROLINA FOREST SERVICE...
WE WILL SIMPLY HIGHLIGHT THE EXPECTED WINDS IN THE NARRATIVE PORTION
OF THE FIRE WEATHER PLANNING FORECAST (FWF).
HIGH CONFIDENCE IN MORE MOIST NE FLOW FOR SUNDAY THROUGH MONDAY AS A
BACKDOOR COLD FRONT AND CAD DEVELOP ACROSS OUR REGION.
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...BSD/BLS
SHORT TERM..BADGETT
LONG TERM...BADGETT
AVIATION...MWS
FIRE WX...BADGETT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
240 AM EDT SAT MAR 16 2013
.SYNOPSIS...
A COLD FRONT WILL SETTLE SOUTH THROUGH NORTH CAROLINA TONIGHT
THEN STALL OVER SOUTH CAROLINA SUNDAY INTO MONDAY. CHILLY HIGH
PRESSURE WILL BUILD SOUTHWARD FROM NEW ENGLAND INTO OUR REGION
SUNDAY INTO MONDAY. A COLD FRONT WILL SURGE EAST THROUGH THE REGION
TUESDAY MORNING.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 940 PM FRIDAY...
DISTURBED NORTHWESTERLY FLOW CONTINUES ALOFT...WHILE A COLD FRONT
DRAPED ACROSS THE MIDWEST IS SLOWLY SINKING SOUTH ACROSS THE OH
VALLEY REGION. OROGRAPHICALLY ENHANCED CIRRUS HAS DIMINISHED SINCE
EARLY IN THE AFTERNOON...AND CIRRUS IS MORE PATCHY ACROSS MUCH OF
THE REGION. WITH THIS TEMPORARY CLEARING...TEMPS HAVE FALLEN A BIT
MORE QUICKLY THAN FORECAST...BUT A LIGHT SOUTHWESTERLY WIND WILL
CONTINUE...SO WILL ONLY MAKE A FEW MINOR ADJUSTMENT TO TEMPS...WITH
MID 40S NORTHEAST TO UPPER 40S SOUTHWEST. TO OUR WEST... STRONG
WARM ADVECTION IS UNDERWAY ACROSS THE MID MS RIVER VALLEY REGION AND
IT FEEDING AN AREA OF SHOWERS MOVING ALONG THE AFOREMENTIONED COLD
FRONT...APPROACHING EASTERN KENTUCKY AND WEST VIRGINIA. EARLIER
RUNS OF THE HRRR WERE SHOWING SHOWERS SPREADING INTO CENTRAL NC AS
THE LOW LEVEL THETA E RIDGE NOSES EASTWARD. CONSIDERED ADDING A
SLIGHT CHANCE POP NEAR THE VA BORDER OVERNIGHT...BUT THE HRRR (AND
OTHER CAMS) APPEARS OVERDONE...AND ANY SHOWERS SEEM MORE LIKELY
AFTER SUNRISE WITH ADDITIONAL HEATING/LOW LEVEL MOISTURE AND BETTER
INSTABILITY. -BLS
SATURDAY
AFOREMENTIONED S/W AND ASSOCIATED SURFACE LOW WILL TRACK ACROSS
CENTRAL AND SOUTHERN VA ON SATURDAY. THIS COUPLED WITH SOME WEAK
INSTABILITY WILL SUPPORT AND AREA OF SHOWERS AND STORMS ACROSS
PORTIONS OF VA... INVOF THE STALLED FRONT (BECOMING A COLD FRONT
SATURDAY NIGHT AS THE SURFACE LOW MOVES TO THE EAST OF THE AREA).
SOME OF THESE SHOWERS AND STORMS MAY MAKE IT INTO NORTHERN PORTIONS
OF CENTRAL NC... NEAR THE NC/VA BORDER. FOR NOW WILL CONTINUE TO
SHOW ONLY A LOW END CHANCE/SLIGHT CHANCE POPS FOR LOCATIONS NEAR THE
NC/VA BORDER. GIVEN DEEP LAYER SHEAR VALUES APPROACHING 50 KTS...
COUPLED WITH SOME WEAK INSTABILITY THINK WE STILL HAVE AT LEAST A
SMALL THREAT OF AT LEAST A STRONG STORM OR TWO NEAR THE NC/VA BORDER
TOMORROW (IF WE GET ANY STORMS THAT MAKE IT INTO OUR AREA).
HOWEVER... WITH DEWPOINTS IN THE 40S EXPECTED AND MARGINAL
INSTABILITY (WITH THE MID LEVEL CAP NOT WEAKENING UNTIL VERY LATE IN
THE DAY) THINK THE WINDOW FOR A SVR STORM OR TWO REMAINS QUITE
SMALL. GIVEN THE RATHER LOW DEWPOINTS AND DRY SUB-CLOUD LAYER EXPECT
OUR MAIN THREAT WILL BE DAMAGING WINDS... ALONG WITH POSSIBLY SOME
HAIL THANKS TO THE IMPRESSIVE SHEAR. GIVEN THE REASON FOR ONLY A
VERY SMALL AND BIT UNCERTAIN THREAT OF SVR STORMS... SPC HAS REMOVED
THE SLIGHT RISK FOR SATURDAY. THE BIGGER STORY ON SATURDAY MAY BE
THE GUSTY WINDS... WITH WIND GUSTS OF UP TO 30 TO 33 MPH POSSIBLE.
THANKS TO THE BIT FARTHER NORTHWARD PLACEMENT OF THE FRONT ON
SATURDAY... AND A BIT LESS CHANCE OF PRECIP... EXPECT HIGHS TO BE IN
THE MID TO UPPER 70S... WITH EVEN SOME TEMPS AROUND 80 POSSIBLE.
SATURDAY NIGHT AND SUNDAY...A MID-UPPER LEVEL S/W CROSSING NEW
ENGLAND WILL NUDGE A SFC COLD FRONT SWD INTO CENTRAL NC. ANY SHOWERS
OR T-STORMS ALONG THIS FEATURE WILL DIMINISH WITH TIME AS FRONT
ENCOUNTERS A SLIGHTLY DRIER AND MORE STABLE AIR MASS. SHORT TERM
MODEL GUIDANCE IN GOOD AGREEMENT...DEPICTING THE SFC BOUNDARY
STALLING ACROSS OUR SOUTHERN COUNTIES BY EARLY SUN. MIN TEMPS VARY
FROM THE LOWER 40S FAR NORTH TO THE LOWER 50S SOUTH.
A SERIES OF PERTURBATIONS IN THE WLY FLOW ALOFT WILL GRADUALLY
INCREASE MID LEVEL CONFLUENCE ACROSS NORTHERN NC/SOUTHERN VA
SUNDAY...MAINTAINING A MOISTURE AXIS OVER THIS REGION.
MEANWHILE...A S-SW FLOW WILL DEVELOP A FEW THOUSAND FT ABOVE THE
SURFACE...SETTING UP AN OVERRUNNING PRECIP EVENT. THIS SHOULD LEAD
TO AN INCREASE IN RAIN COVERAGE NORTH OF THE BOUNDARY DURING THE DAY
SUNDAY. EXTENT OF PRECIP WILL DETERMINE MAX TEMPS. IF RAIN MORE
WIDESPREAD THAN CURRENTLY EXPECTED...TEMPS IN THE TRIAD AND TRIANGLE
REGIONS MAY END UP 5-8 DEGREES COOLER THAN FORECAST.
CONVERSELY...TEMPS NEAR OR SOUTH OF THE BOUNDARY COULD BE IN THE
LOW-MID 70S...DEPENDING ON THE AMOUNT OF CLOUD COVERAGE. IF FRONT
DRIFTS INTO SC...MAX TEMPS IN FAY REGION MAY BE AS MUCH AS 5-6
DEGREES COOLER THAN FORECAST.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH 12Z TUESDAY/...
AS OF 200 AM SATURDAY...
...HIGH CONFIDENCE IN THAT COLD AIR DAMMING (CAE) WILL PREVAIL
ACROSS OUR REGION SUNDAY NIGHT THROUGH MONDAY...
THE MODELS ARE FINALLY COMING AROUND TO FORECASTING A COLD AIR
DAMMING EVENT IN OUR PIEDMONT DAMMING REGION SUNDAY NIGHT AND
MONDAY. THE MODELS ARE TYPICALLY SLOW TO CATCH ON TO CAD EVEN IN
THIS CASE WHEN THE PARENT SURFACE HIGH IS FORECAST (AS HAS BEEN FOR
SEVERAL DAYS) TO BE MORE THAN SUFFICIENT STRENGTH (1025 MB)... AND
LOCATION (PA/NY STATE)... TO DELIVER THE DRY COLD AIR INTO OUR
REGION. THE OTHER PLAYER (QPF) WHICH NEEDS TO BE IN GENERAL NEAR
0.10 TO LOCK IN THE CAD ALSO APPEARS LIKELY. THEREFORE... WITH ALL
THREE MAJOR PLAYERS EXPECTED TO BE POSITIVE... THEN WITH HIGH
CONFIDENCE CAD WILL BE FORECAST.
THE MOST DIFFICULT PART OF THE FORECAST WILL BE THE QPF ASSOCIATED
WITH THE ISENTROPIC LIFT INITIALLY WITH THE FRONT TO OUR SOUTH
SUNDAY INTO EARLY MONDAY... THEN WITH THE MAIN STORM TRACK EXPECTED
TO BE WEST OF THE MOUNTAINS MONDAY NIGHT. THE ENDING OF THE CAD WILL
LIKELY BE THE ACTUAL COLD FRONTAL PASSAGE EARLY TUESDAY FROM THE
WEST.
SENSIBLE WEATHER WILL INCLUDE: CLOUDY AND COOL SUNDAY NIGHT AND
MONDAY WITH THE LOW LEVEL NE FLOW... AND UPPER LEVEL SW FLOW.
OCCASIONAL LIGHT RAIN/DRIZZLE IN THE DAMMING REGION AND A CHANCE OF
RAIN SE. LOWS SUNDAY NIGHT 35-40 PIEDMONT DAMMING REGION... AND
40-45 SE. HIGHS MONDAY IN THE 40S WEST AND NORTH RANGING INTO THE
LOWER 50S SE. TEMPS MONDAY NIGHT WILL EITHER HOLD STEADY OR SLOWLY
RISE AS THE MAIN LOW PRESSURE LIFTS THROUGH THE TN VALLEY TOWARD NY
STATE BY 12Z/TUE. THE CAD BOUNDARY WILL TRY TO LIFT BACK NW-N... BUT
SHOULD HAVE PLENTY OF COOL STABLE AIR TO PROVIDE RESISTANCE IN THE
PIEDMONT. THIS SHOULD LEAD TO AREAS OF DENSE FOG IN THE DAMMING
REGION LATE MONDAY INTO MONDAY NIGHT. OTHERWISE... OCCASIONAL RAIN
MAINLY WEST... AND A CHANCE OF RAIN EAST. LOWS 40S TO LOWER 50S THEN
RISING... ESPECIALLY EAST TO AROUND 60.
THE QPF APPEARS THAT IT WILL BE HIGHEST IN THE DAMMING REGION AND
CLOSEST TO THE STORM TRACK TO OUR WEST FOR THIS EVENT. WE WILL
FORECAST 0.25 TO 0.50 OF AN INCH IN THE NW... AND LESS THAN 0.20 IN
THE SE.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 230 AM SATURDAY...
THE ARCTIC OSCILLATION AND THE NORTH ATLANTIC OSCILLATION HAVE BOTH
BEEN RUNNING STRONGLY NEGATIVE RECENTLY. THE RESULTANT UPPER AIR
PATTERN HAS BEEN ONE THAT HAS FEATURED THE MAIN TROUGH OVER THE
EASTERN UNITED STATES WITH COLDER THAN NORMAL TEMPERATURES. THE
FIRST TWO WEEKS OF MARCH HAVE BEEN 4-5 DEGREES COLDER THAN THE 30
YEAR STATISTICAL AVERAGE AT KGSO/KRDU/AND KFAY.
THE FORECAST FOR THE MIDDLE TO LATTER HALF OF THIS WEEKS CONTINUES
TO LOOK COLDER THAN NORMAL OVERALL. THE MAIN FLOW PATTERN IS
EXPECTED TO CONTINUE TO BE DRIVEN BY THE STRONGLY NEGATIVE AO/NAO...
WITH A DEEP TROUGH OVER THE CENTRAL AND EASTERN UNITED STATES. THIS
SHOULD LEAD TO A SIGNIFICANT PRECIPITATION EVENT FOR OUR REGION BY
FRI OR OVER THE WEEKEND.
SENSIBLE WEATHER:
TUESDAY... THE CAD WILL BE BROKEN UP AS THE MAIN COLD FRONT SURGES
EAST THROUGH THE REGION EARLY MORNING. STRONG SUBSIDENCE IN THE REAR
OF THE DEPARTING TROUGH/FRONT WILL LEAD TO CLEARING AND BREEZY
CONDITIONS. THE WNW FLOW WILL BE DOWNSLOPE DURING THE DAY ALLOWING
FOR A MILD DAY... BEFORE CAA SETS IN LATER. EXPECT SKIES TO BECOME
MOSTLY SUNNY. HIGHS GENERALLY IN THE MID 60S NORTHWEST AND 70-75
ELSEWHERE. TUESDAY NIGHT AND WEDNESDAY... MOSTLY CLEAR AND COOLER.
LOWS IN THE 30S. HIGHS WEDNESDAY IN THE MID 50S TO LOWER 60S.
THURSDAY AND FRIDAY... CHILLY. INCREASING CLOUDINESS THURSDAY NIGHT.
A CHANCE OF RAIN BY FRIDAY. LOWS THURSDAY 30-35 NW AND MID 30S SE.
HIGHS THURSDAY IN THE 50S. LOWS THURSDAY NIGHT 35-40. HIGHS FRIDAY
IN THE 40S NW AND 50S SE.
IT IS UNCLEAR AT THE MOMENT IN THE STRENGTH AND POSITION OF A
POTENTIAL CAD HIGH AGAIN FOR THIS SYSTEM. HOWEVER... IT DOES APPEAR
LIKELY THAT ANOTHER STRONG MID-UPPER TROUGH WILL OCCUPY THE MIDWEST
TO GREAT LAKES AND OUR REGION BEYOND SATURDAY. THIS WOULD BRING
ANOTHER WEEK OF MUCH BELOW NORMAL TEMPERATURES TO CENTRAL NC
PREVENTING AN EARLY WARM SPRING.
&&
.AVIATION /00Z FRIDAY THROUGH WEDNESDAY/...
AS OF 757 PM FRIDAY...
24 HOUR TAF PERIOD:
WIND GUSTS HAVE DIMINISHED... HOWEVER WINDS WILL REMAIN SW AT 5-10
KT OVERNIGHT... BEFORE GUSTS TO AROUND 20 KTS BEGIN AGAIN IN THE
MORNING HOURS SATURDAY. THERE IS A CHANCE OF SHOWERS WITH THE
POSSIBILITY OF SOME STORMS AT KINT AND KGSO IN THE AFTERNOON AND
EVENING IN ASSOCIATION WITH A FRONTAL ZONE NEAR THE NC/VA BORDER.
LOOKING AHEAD:
SUB-VFR CONDITIONS WITH RAIN AND DRIZZLE... MOST LIKELY IN THE
FAVORED COLD AIR DAMMING REGION AT KGSO AND KINT... ARE EXPECTED
SUNDAY INTO MONDAY... BEFORE A COLD FRONT MOVES THROUGH THE AREA
TUESDAY AFTERNOON AND BRINGS A RETURN TO VFR CONDITIONS.
&&
.FIRE WEATHER...
AS OF 236 AM SATURDAY...
SOUTHWEST WINDS SUSTAINED AT 15-20 MPH WITH FREQUENT GUSTS TO 30 MPH
ARE EXPECTED TODAY. MINIMUM RELATIVE HUMIDITY VALUES IN THE
AFTERNOON WILL BE IN THE 30-40 PERCENT RANGE MOST AREAS... REMAINING
ABOVE THE CRITICAL FIRE WEATHER THRESHOLD OF 25 PERCENT OR BELOW.
PER PREVIOUS DISCUSSION WITH THE NORTH CAROLINA FOREST SERVICE...
WE WILL SIMPLY HIGHLIGHT THE EXPECTED WINDS IN THE NARRATIVE PORTION
OF THE FIRE WEATHER PLANNING FORECAST (FWF).
HIGH CONFIDENCE IN MORE MOIST NE FLOW FOR SUNDAY THROUGH MONDAY AS A
BACKDOOR COLD FRONT AND CAD DEVELOP ACROSS OUR REGION.
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...BSD/BLS
SHORT TERM..BADGETT
LONG TERM...BADGETT
AVIATION...SEC
FIRE WX...BADGETT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
205 AM EDT SAT MAR 16 2013
.SYNOPSIS...
A COLD FRONT WILL SETTLE SOUTH THROUGH NORTH CAROLINA TONIGHT
THEN STALL OVER SOUTH CAROLINA SUNDAY INTO MONDAY. CHILLY HIGH
PRESSURE WILL BUILD SOUTHWARD FROM NEW ENGLAND INTO OUR REGION
SUNDAY INTO MONDAY. A COLD FRONT WILL SURGE EAST THROUGH THE REGION
TUESDAY MORNING.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 940 PM FRIDAY...
DISTURBED NORTHWESTERLY FLOW CONTINUES ALOFT...WHILE A COLD FRONT
DRAPED ACROSS THE MIDWEST IS SLOWLY SINKING SOUTH ACROSS THE OH
VALLEY REGION. OROGRAPHICALLY ENHANCED CIRRUS HAS DIMINISHED SINCE
EARLY IN THE AFTERNOON...AND CIRRUS IS MORE PATCHY ACROSS MUCH OF
THE REGION. WITH THIS TEMPORARY CLEARING...TEMPS HAVE FALLEN A BIT
MORE QUICKLY THAN FORECAST...BUT A LIGHT SOUTHWESTERLY WIND WILL
CONTINUE...SO WILL ONLY MAKE A FEW MINOR ADJUSTMENT TO TEMPS...WITH
MID 40S NORTHEAST TO UPPER 40S SOUTHWEST. TO OUR WEST... STRONG
WARM ADVECTION IS UNDERWAY ACROSS THE MID MS RIVER VALLEY REGION AND
IT FEEDING AN AREA OF SHOWERS MOVING ALONG THE AFOREMENTIONED COLD
FRONT...APPROACHING EASTERN KENTUCKY AND WEST VIRGINIA. EARLIER
RUNS OF THE HRRR WERE SHOWING SHOWERS SPREADING INTO CENTRAL NC AS
THE LOW LEVEL THETA E RIDGE NOSES EASTWARD. CONSIDERED ADDING A
SLIGHT CHANCE POP NEAR THE VA BORDER OVERNIGHT...BUT THE HRRR (AND
OTHER CAMS) APPEARS OVERDONE...AND ANY SHOWERS SEEM MORE LIKELY
AFTER SUNRISE WITH ADDITIONAL HEATING/LOW LEVEL MOISTURE AND BETTER
INSTABILITY. -BLS
SATURDAY
AFOREMENTIONED S/W AND ASSOCIATED SURFACE LOW WILL TRACK ACROSS
CENTRAL AND SOUTHERN VA ON SATURDAY. THIS COUPLED WITH SOME WEAK
INSTABILITY WILL SUPPORT AND AREA OF SHOWERS AND STORMS ACROSS
PORTIONS OF VA... INVOF THE STALLED FRONT (BECOMING A COLD FRONT
SATURDAY NIGHT AS THE SURFACE LOW MOVES TO THE EAST OF THE AREA).
SOME OF THESE SHOWERS AND STORMS MAY MAKE IT INTO NORTHERN PORTIONS
OF CENTRAL NC... NEAR THE NC/VA BORDER. FOR NOW WILL CONTINUE TO
SHOW ONLY A LOW END CHANCE/SLIGHT CHANCE POPS FOR LOCATIONS NEAR THE
NC/VA BORDER. GIVEN DEEP LAYER SHEAR VALUES APPROACHING 50 KTS...
COUPLED WITH SOME WEAK INSTABILITY THINK WE STILL HAVE AT LEAST A
SMALL THREAT OF AT LEAST A STRONG STORM OR TWO NEAR THE NC/VA BORDER
TOMORROW (IF WE GET ANY STORMS THAT MAKE IT INTO OUR AREA).
HOWEVER... WITH DEWPOINTS IN THE 40S EXPECTED AND MARGINAL
INSTABILITY (WITH THE MID LEVEL CAP NOT WEAKENING UNTIL VERY LATE IN
THE DAY) THINK THE WINDOW FOR A SVR STORM OR TWO REMAINS QUITE
SMALL. GIVEN THE RATHER LOW DEWPOINTS AND DRY SUB-CLOUD LAYER EXPECT
OUR MAIN THREAT WILL BE DAMAGING WINDS... ALONG WITH POSSIBLY SOME
HAIL THANKS TO THE IMPRESSIVE SHEAR. GIVEN THE REASON FOR ONLY A
VERY SMALL AND BIT UNCERTAIN THREAT OF SVR STORMS... SPC HAS REMOVED
THE SLIGHT RISK FOR SATURDAY. THE BIGGER STORY ON SATURDAY MAY BE
THE GUSTY WINDS... WITH WIND GUSTS OF UP TO 30 TO 33 MPH POSSIBLE.
THANKS TO THE BIT FARTHER NORTHWARD PLACEMENT OF THE FRONT ON
SATURDAY... AND A BIT LESS CHANCE OF PRECIP... EXPECT HIGHS TO BE IN
THE MID TO UPPER 70S... WITH EVEN SOME TEMPS AROUND 80 POSSIBLE.
SATURDAY NIGHT AND SUNDAY...A MID-UPPER LEVEL S/W CROSSING NEW
ENGLAND WILL NUDGE A SFC COLD FRONT SWD INTO CENTRAL NC. ANY SHOWERS
OR T-STORMS ALONG THIS FEATURE WILL DIMINISH WITH TIME AS FRONT
ENCOUNTERS A SLIGHTLY DRIER AND MORE STABLE AIR MASS. SHORT TERM
MODEL GUIDANCE IN GOOD AGREEMENT...DEPICTING THE SFC BOUNDARY
STALLING ACROSS OUR SOUTHERN COUNTIES BY EARLY SUN. MIN TEMPS VARY
FROM THE LOWER 40S FAR NORTH TO THE LOWER 50S SOUTH.
A SERIES OF PERTURBATIONS IN THE WLY FLOW ALOFT WILL GRADUALLY
INCREASE MID LEVEL CONFLUENCE ACROSS NORTHERN NC/SOUTHERN VA
SUNDAY...MAINTAINING A MOISTURE AXIS OVER THIS REGION.
MEANWHILE...A S-SW FLOW WILL DEVELOP A FEW THOUSAND FT ABOVE THE
SURFACE...SETTING UP AN OVERRUNNING PRECIP EVENT. THIS SHOULD LEAD
TO AN INCREASE IN RAIN COVERAGE NORTH OF THE BOUNDARY DURING THE DAY
SUNDAY. EXTENT OF PRECIP WILL DETERMINE MAX TEMPS. IF RAIN MORE
WIDESPREAD THAN CURRENTLY EXPECTED...TEMPS IN THE TRIAD AND TRIANGLE
REGIONS MAY END UP 5-8 DEGREES COOLER THAN FORECAST.
CONVERSELY...TEMPS NEAR OR SOUTH OF THE BOUNDARY COULD BE IN THE
LOW-MID 70S...DEPENDING ON THE AMOUNT OF CLOUD COVERAGE. IF FRONT
DRIFTS INTO SC...MAX TEMPS IN FAY REGION MAY BE AS MUCH AS 5-6
DEGREES COOLER THAN FORECAST.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH 12Z TUESDAY/...
AS OF 200 AM SATURDAY...
...HIGH CONFIDENCE IN THAT COLD AIR DAMMING (CAE) WILL PREVAIL
ACROSS OUR REGION SUNDAY NIGHT THROUGH MONDAY...
THE MODELS ARE FINALLY COMING AROUND TO FORECASTING A COLD AIR
DAMMING EVENT IN OUR PIEDMONT DAMMING REGION SUNDAY NIGHT AND
MONDAY. THE MODELS ARE TYPICALLY SLOW TO CATCH ON TO CAD EVEN IN
THIS CASE WHEN THE PARENT SURFACE HIGH IS FORECAST (AS HAS BEEN FOR
SEVERAL DAYS) TO BE MORE THAN SUFFICIENT STRENGTH (1025 MB)... AND
LOCATION (PA/NY STATE)... TO DELIVER THE DRY COLD AIR INTO OUR
REGION. THE OTHER PLAYER (QPF) WHICH NEEDS TO BE IN GENERAL NEAR
0.10 TO LOCK IN THE CAD ALSO APPEARS LIKELY. THEREFORE... WITH ALL
THREE MAJOR PLAYERS EXPECTED TO BE POSITIVE... THEN WITH HIGH
CONFIDENCE CAD WILL BE FORECAST.
THE MOST DIFFICULT PART OF THE FORECAST WILL BE THE QPF ASSOCIATED
WITH THE ISENTROPIC LIFT INITIALLY WITH THE FRONT TO OUR SOUTH
SUNDAY INTO EARLY MONDAY... THEN WITH THE MAIN STORM TRACK EXPECTED
TO BE WEST OF THE MOUNTAINS MONDAY NIGHT. THE ENDING OF THE CAD WILL
LIKELY BE THE ACTUAL COLD FRONTAL PASSAGE EARLY TUESDAY FROM THE
WEST.
SENSIBLE WEATHER WILL INCLUDE: CLOUDY AND COOL SUNDAY NIGHT AND
MONDAY WITH THE LOW LEVEL NE FLOW... AND UPPER LEVEL SW FLOW.
OCCASIONAL LIGHT RAIN/DRIZZLE IN THE DAMMING REGION AND A CHANCE OF
RAIN SE. LOWS SUNDAY NIGHT 35-40 PIEDMONT DAMMING REGION... AND
40-45 SE. HIGHS MONDAY IN THE 40S WEST AND NORTH RANGING INTO THE
LOWER 50S SE. TEMPS MONDAY NIGHT WILL EITHER HOLD STEADY OR SLOWLY
RISE AS THE MAIN LOW PRESSURE LIFTS THROUGH THE TN VALLEY TOWARD NY
STATE BY 12Z/TUE. THE CAD BOUNDARY WILL TRY TO LIFT BACK NW-N... BUT
SHOULD HAVE PLENTY OF COOL STABLE AIR TO PROVIDE RESISTANCE IN THE
PIEDMONT. THIS SHOULD LEAD TO AREAS OF DENSE FOG IN THE DAMMING
REGION LATE MONDAY INTO MONDAY NIGHT. OTHERWISE... OCCASIONAL RAIN
MAINLY WEST... AND A CHANCE OF RAIN EAST. LOWS 40S TO LOWER 50S THEN
RISING... ESPECIALLY EAST TO AROUND 60.
THE QPF APPEARS THAT IT WILL BE HIGHEST IN THE DAMMING REGION AND
CLOSEST TO THE STORM TRACK TO OUR WEST FOR THIS EVENT. WE WILL
FORECAST 0.25 TO 0.50 OF AN INCH IN THE NW... AND LESS THAN 0.20 IN
THE SE.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 230 PM FRIDAY...
STRONG SUBSIDENCE BEHIND THE EXITING SYSTEM SHOULD LEAD TO RAPID
CLEARING. TIGHT PRESSURE GRADIENT BETWEEN A SURFACE LOW OVER
SOUTHERN NEW ENGLAND AND A HIGH OVER THE LOWER MS VALLEY WILL CAUSE
BREEZY CONDITIONS TUESDAY. MIN TEMPS MONDAY NIGHT UPPER 40S NW TO
MID 50S SE. HIGH TEMPS TUESDAY NEAR 60 NW TO UPPER 60S SE.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT....COOL STABLE AIR MASS WILL
OVERSPREAD CENTRAL NC AS MODIFIED CANADIAN HIGH BUILDS INTO THE
REGION FROM THE NW. DAYTIME TEMPS WED WILL AVERAGE 7-9 DEGREES BELOW
NORMAL. A BACKDOOR COLD FRONT WILL CROSS THE REGION WEDNESDAY
NIGHT...STALLING ACROSS SC THU.
THURSDAY INTO FRIDAY...A COOL AND POTENTIAL WET SCENARIO POSSIBLY
UNFOLDING THIS PERIOD THOUGH TIMING STILL IN QUESTION. A S/W WILL
EXIT THE SOUTHERN PLAINS AND APPROACH THE SE U.S. LATE THU-THU
NIGHT. THIS FEATURE SHOULD INCREASE THE LOW LEVEL SLY FLOW ABOVE THE
STABLE AIR MASS AT THE SURFACE. THIS SUGGEST POTENTIAL FOR AN
OVERRUNNING EVENT...AS WELL AS A HYBRID DAMMING EPISODE. WILL
MAINTAIN TEMPS 7-10 DEGREES BELOW NORMAL AND HAVE SLIGHT CHANCE POPS
FOR NOW SINCE TIMING STILL IN QUESTION.
&&
.AVIATION /00Z FRIDAY THROUGH WEDNESDAY/...
AS OF 757 PM FRIDAY...
24 HOUR TAF PERIOD:
WIND GUSTS HAVE DIMINISHED... HOWEVER WINDS WILL REMAIN SW AT 5-10
KT OVERNIGHT... BEFORE GUSTS TO AROUND 20 KTS BEGIN AGAIN IN THE
MORNING HOURS SATURDAY. THERE IS A CHANCE OF SHOWERS WITH THE
POSSIBILITY OF SOME STORMS AT KINT AND KGSO IN THE AFTERNOON AND
EVENING IN ASSOCIATION WITH A FRONTAL ZONE NEAR THE NC/VA BORDER.
LOOKING AHEAD:
SUB-VFR CONDITIONS WITH RAIN AND DRIZZLE... MOST LIKELY IN THE
FAVORED COLD AIR DAMMING REGION AT KGSO AND KINT... ARE EXPECTED
SUNDAY INTO MONDAY... BEFORE A COLD FRONT MOVES THROUGH THE AREA
TUESDAY AFTERNOON AND BRINGS A RETURN TO VFR CONDITIONS.
&&
.FIRE WEATHER...
AS OF 400 PM FRIDAY...
SOUTHWEST WINDS SATURDAY WILL GUST FREQUENTLY AROUND 30 MPH LATE IN
THE MORNING THROUGH THE AFTERNOON. MINIMUM RH VALUES IN THE
AFTERNOON WILL BE IN THE 30S MOST LOCATIONS...NEAR 40 PERCENT IN THE
FAR NORTHEAST. PER DISCUSSION WITH THE NC FORESTRY SERVICE...WILL
HIGHLIGHT WINDS IN THE NARRATIVE PORTION OF THE FIRE WEATHER
PLANNING FORECAST.
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...BSD/BLS
SHORT TERM..BADGETT
LONG TERM...WSS
AVIATION...SEC
FIRE WX...WSS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
310 PM EDT SAT MAR 16 2013
.SYNOPSIS...
COLD FRONT SLOWLY CROSSES THIS EVENING BUT RETURNS NORTH SUNDAY AND
STALLS NEAR THE REGION. WAVE MOVES ALONG THE FRONT MONDAY. COLD
FRONT MONDAY NIGHT. COLDER TUESDAY.
&&
.NEAR TERM /THROUGH SUNDAY/...
EARLIER FCST THINKING GENERALLY ON TRACK. COVERAGE OF SHRA
INCREASING AS EXPECTED ACROSS WESTERN LOWLANDS AS OF 18Z. THIS
SHOULD CONT TO DEVELOP NEXT FEW HRS AS IT HEADS S WITH COLD FRONT.
SHOULD BEGIN TO SEE SOME CONVECTION AS WELL. DESPITE MEAGER
MOISTURE INFLUX...SOME SFC INSTABILITY REALIZED THIS AFTN ALONG
AND S OF I64 CORRIDOR WHERE SFC TEMPS HAVE CLIMBED INTO THE UPR
60S TO LWR 70S. RAP DEPICTS SFC CAPE GENERALLY 300 TO 500 J/KG
ACROSS SAID AREA. LLVL INVERTED V SOUNDINGS CONT TO SUGGEST SOME
WIND CONCERNS AS WELL. HAVE BEEN SEEING GENERAL 20 TO 25 KTS IN
GUSTS WITHOUT ANY SHRA/TSRA. LOW FZ LVLS MAY RESULT IN SOME HAIL
AS WELL FOR ANY DEEPER CONVECTION.
ALL OF THIS EXITS SW VA AND SE OH BY 00Z WITH FROPA. IMPRESSIVE
CAA THIS EVE WILL MAKE THIS AFTNS 70 DEGREE WX ACROSS PORTIONS OF
AREA...SEEM LIKE A DISTANT MEMORY.
THIS MARKS A TRANSITION BACK TO WINTER HEADING THRU TOMORROW AND
THE NEXT FCST HEADACHE. FRONT WILL BEGIN RETURNING N AS A WARM
DURING THE DAY WITH IMPRESSIVE ISENTROPIC LIFT ALLOW PCPN TO BREAK
OUT ALONG BOUNDARY. MOST OF MDLS ARE IN AGREEMENT WITH THE
POSITION OF THIS BOUNDARY DURING THE DAY...MAKING IT TO I64
CORRIDOR BY 21Z TO NEAR ATH-PKB-W22 BY 00Z. ALL OF THIS LEADS TO
PCPN CONUNDRUMS. DESPITE H85 TEMPS MARGINAL...LIFT IS DEEP ENOUGH
FOR SNOW SOUNDINGS N OF BOUNDARY...PROVIDED SFC TEMPS COOPERATE.
THINK SOME OF THE GUIDANCE NUMBERS ARE TOO HIGH FOR TOMORROW. WILL
HEDGE TOWARD COLDER MET DURING THE DAY WHICH APPEARS TO CAPTURE
WETBULBING DOWN TOWARD LWR 30S. THIS ALLOWS FOR A MIX ALONG I64
CORRIDOR WITH WET SN ON THE HILLS...TRANSITIONING TO MOSTLY SN N
OF I64. WILL KEEP ACCUM DOWN FOR NOW GIVEN TIME OF YEAR...WARM DAY
TDY...AND TIMING OF PCPN IN AFTN. DID CODE UP SOME COATINGS ON THE
HILLS WITH GENERAL 2 TO 3 INCHES IN N MTNS. COULD SEE SOME
COATINGS TOWARD VALLEY FLOORS IF PCPN COMES DOWN HARD ENOUGH. WILL
HOLD OFF ON ANY HEADLINES AFTER COORDINATING WITH SHORT TERM
FCSTER AND SURROUNDING OFFICES. TOO MUCH UNCERTAINTY ATTM GIVEN
SENSITIVE NATURE TO LOCATION OF BOUNDARY AND SFC TEMPS.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
MODELS HAVE BECOME VERY INTERESTING FOR SUNDAY AFTERNOON THROUGH
MONDAY MORNING. THIS WILL DEPEND ULTIMATELY ON HOW FAR SOUTH THE
COLD FRONT MAKES IT...ESPECIALLY THE COLD AIR NORTH OF THE FRONT.
MODELS ARE CURRENTLY INSISTING ON A BAND OF SNOW ACROSS SOUTHEAST
OHIO AND NORTHERN WEST VIRGINIA. WITH MODELS CHANGING CONSIDERABLY
FROM PREVIOUS RUNS AND SNOW BAND EXPECTED TO BE FAIRLY NARROW...WILL
HOLD OFF ON HEADLINES FOR THE MOMENT. SOUTHEAST UPSLOPE COULD ALSO
BE A CRITICAL FACTOR WITH ICING NOT OUT OF THE QUESTION.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
OVERALL...PATTERN NOT CHANGING MUCH AND STILL EXPECT COOLER THAN
NORMAL CONDITIONS IN THE WAKE OF THE STRONG COLD FRONT MONDAY
NIGHT. BIGGEST QUESTION OF THE FORECAST REMAINS THE COLD POOL LOW
LEVEL STRATUS DECK AND POTENTIAL FOR PRECIPITATION...BOTH LOWLANDS
AND THE MOUNTAINS. TRIED TO GO WITH MORE OF A CONSENSUS IN THE
OPERATIONAL GFS AND ECMWF MODELS IN TERMS OF ADDING
PRECIPITATION...BUT KEEP THE BULK OF ANY WEATHER REQUIRING AMOUNTS
IN THE SLIGHT CHANCE RANGE TO LOW END CHANCE.
WILL STRUGGLE TO SEE ANY LOWLAND TEMPERATURES CLIMB ABOVE 50F OVER
THE DURATION...WITH THE HIGHEST MOUNTAINS IN THE NORTHEAST
STRUGGLING TO GET ABOVE FREEZING AT THE HIGHEST
ELEVATIONS...INCLUDING SNOWSHOE. CONTINUE TO CARRY OVERNIGHT LOWS
AREA WIDE DROPPING BELOW FREEZING THROUGH THE DURATION.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
COLD FRONT WORKING THRU SE OH AS OF 19Z. LINE OF SHRA AND SOME
CONVECTION ORGANIZING ACROSS C LOWLANDS...AFFECTING KCRW WITH
MVFR VSBY PERHAPS. THIS ALL SLIDES SE THRU LATE AFTN WITH BAND
WORKING THRU KBKW BY 21Z. NOT EXPECTING ANYTHING FROM N TAF SITES
AS FAR AS PCPN GOES. LOOKING FOR POST FRONTAL MVFR STRATUS TONIGHT
MOST TAF SITES...WITH PERHAPS SOME IMPROVEMENT OH RVR SITES LATE.
WILL WATCH FOR BOUNDARY TO RETURN N AS WARM FRONT ON SUNDAY.
IMPRESSIVE LIFT WILL ALLOW PCPN TO BREAK OUT ALONG AND N OF
BOUNDARY IN THE FORM OF A MIX ACROSS THE CENTRAL LOWLANDS AND SOME
WET SN N MTNS. HAVE A MIX IN KCRW AND KHTS TAFS BY 18Z. GENERAL
MVFR CIGS AND IFR VSBY EXPECTED AFTERWARD DEPENDING ON PCPN TYPE.
GUSTY W WINDS 20 TO 25 KTS REMAINDER OF AFTN SWITCHES MORE NW THIS
EVE AND WANES. SOME HIGHER GUSTS IN CONVECTION ACROSS SE WV THRU
21Z. FLOW TURNS MORE N THEN NE ON SUNDAY N OF WARM FRONT WITH MOD
SW FLOW ALOFT.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY...
FORECAST CONFIDENCE...MEDIUM.
ALTERNATE SCENARIOS: COLD FRONT TIMING AND RESULTING CONDITIONS
MAY VARY THIS AFTN.
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 H H H H H H H H H H H H
HTS CONSISTENCY H H H M H H H H H H H H
BKW CONSISTENCY H H H H H H M M H H H H
EKN CONSISTENCY L L L L L L L L L L L L
PKB CONSISTENCY H H H H H H H H M M M M
CKB CONSISTENCY M H H H H H H H H H H H
AFTER 18Z SUNDAY...
IFR POSSIBLE SUNDAY INTO MONDAY NIGHT IN PRECIP.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30/26
NEAR TERM...30
SHORT TERM...KTB
LONG TERM...26
AVIATION...30
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
404 PM EDT SAT MAR 16 2013
.SYNOPSIS...
A WAVE OF LOW PRESSURE WILL TRACK TO THE SOUTH OF THE MASON-
DIXON LINE THIS AFTERNOON...BEFORE SLIDING OFF THE VIRGINIA COAST
TONIGHT. HIGH PRESSURE WILL DRIFT OUT OF THE GREAT LAKES ON SUNDAY
AND RETREAT INTO NEW ENGLAND SUNDAY NIGHT. A COMPLEX FRONTAL
SYSTEM WILL THEN IMPACT THE REGION EARLY NEXT WEEK.
HIGH LATITUDE BLOCKING WILL KEEP AN UPPER TROUGH OVER THE
EASTERN U.S. DURING THE SECOND HALF OF NEXT WEEK WITH BELOW NORMAL
TEMPERATURES LIKELY CONTINUING THROUGH THE START OF ASTRONOMICAL
SPRING.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
THE FAST MOVING LOW AMPLITUDE UPPER WAVE AND WEAK SURFACE LOW WILL
CONTINUE TO RACE ESE ACROSS THE REGION TODAY. LIGHT-MODERATE SNOW
HAS BEEN FALLING SINCE EARLY TODAY WITH SEVERAL REPORTS IN THE 1
TO 2 INCH RANGE...WITH SOME AREAS WITH SLIGHTLY HIGHER NUMBERS
REPORTING IN.
THE THINKING HAS NOT CHANGED SIGNIFICANTLY...WITH MOISTURE FROM
THE SYSTEM REMAINING LIMITED. BUT MID LEVEL DYNAMICS ARE
IMPRESSIVE WITH A TIGHT THERMAL GRADIENT FORECAST TO TIGHTEN IN
TIME. RUC SHOWS POTENT LOW-MID LEVEL FRONTOGENETIC FORCING WITH
THE BACK EDGE ENTERING WESTERN PA AS OF ID DAY. THERE IS ALSO AN
EROSION OF STABILITY EXPECTED THROUGH MID AFTERNOON...WITH THE
ZERO LI LINE POKING INTO FAR SWRN PA. THE FCST PARAMETERS AND
RADAR SUPPORT THE IDEA THAT DESPITE LIMITED MOISTURE...THE
ATMOSPHERE IS WORKING ABOUT AS EFFICIENTLY AS POSSIBLE IN
CRANKING OUT PRECIPITATION.
THE MAIN ISSUES TODAY REMAIN THE MARGINAL SURFACE TEMPERATURES
AND THE EFFECT OF THE RELATIVELY HIGH MID MARCH SUN ANGLES ON THE
FALLING SNOW WHICH IS EXPECTED OVER ABOUT THE NORTHERN HALF OF THE
AREA. AT THIS TIME OF YEAR...DURING THE DAY...IT USUALLY NEEDS TO
SNOW PRETTY HARD FOR ACCUMULATIONS TO OCCUR. HOURLY AND MAX SFC
TEMPS IN THIS CORRIDOR WILL BE IN THE UPPER 20S TO LOWER 30S
EXCEPT FOR THE MIDDLE AND WEST BRANCH PORTION OF THE SUSQ
VALLEY...WHERE TEMPS WILL BE NEARLY STEADY BETWEEN 33-36F TODAY.
THIS WOULD SUGGEST THAT MOST ACCUMS WILL BE LIMITED TO MAINLY
GRASSY AREAS...WHICH ALREADY WHAT WE ARE OBSERVING OUT THE WINDOW
HERE AT THE OFFICE. HOWEVER...UNTREATED ROADS WILL LIKELY BECOME
SLICK WHERE SNOWFALL RATES THAT MAY APPROACH 1/2 INCH OR MORE PER
HOUR AT TIMES ARE OBSERVED.
ACROSS THE SOUTHERN TIER...WARMER BLYR TEMPS WITH SFC TEMPS IN THE
UPPER 30S TO LOWER 40S WILL LEAD TO SNOW...POSSIBLY MIXED RAIN
AT TIMES. THE WARM SKIN TEMPS WILL KEEP SNOW ACCUMS MINIMAL.
PRECIP WILL WIND DOWN RAPIDLY LATER TODAY AND THIS EVENING AS THE
FORCING ASSOCIATED WITH THE WAVE SLIDES BY AND HIGH PRESSURE
PRESSES IN FROM THE NORTH. CLOUDS WILL BE SLOW TO SCOUR OUT
HOWEVER...SO THERE WILL BE SOME CONCERN FOR SPOTTY FREEZING
DRIZZLE INTO THE WEE HOURS. THIS WILL NEED TO BE MONITORED BY THE
EVE SHIFT.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
DIFFERENCES IN THE SHORT RANGE GUIDANCE BEGIN TO SHOW UP AS EARLY
AS DAY TWO WITH THE GFS SHOWING PRECIP ENTERING THE FAR SRN TIER
AS EARLY AS SUNDAY AFTERNOON...WHILE THE NAM IS DRY THROUGH 00Z
MONDAY. THE OLD ECMWF AND CMC ARE IN LINE WITH THE NEW NAM. THE
09Z SREF AND 06Z GEFS LEAN CLOSER TO THE NEW GFS WITH THE
REINTRODUCING OF LIGHT PRECIP OVER THE FAR SOUTH AFTER 18Z.
WITH A COLD HIGH SETTING UP SHOP TO OUR NE..WE LOOK TO BE SETTING
UP FOR A CLASSIC WINTRY MIX SETUP FOR MUCH OF OUR AREA WITH THE
APPROACH OF THE NEXT FRONTAL SYSTEM.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
1030MB HIGH PRES RETREATING INTO NRN NEW ENGLAND WITH WIDESPREAD
COLD AIR DAMMING INITIALLY ENTRENCHED ALONG/EAST OF THE ALLEGHENIES
WILL SET THE STAGE FOR A LATE-SEASON MIXED PRECIP EVENT ON
MONDAY...AS A STRONG EAST-WEST FRONTAL SYSTEM LIFTS NORTHEAST FROM
THE OHIO VALLEY AND MERGES WITH A POTENT SHORTWAVE AND ASSOCIATED
COLD FRONT SWEEPING EWD INTO THE MID-ATLC AND NORTHEAST STATES.
BEHIND THE DEPARTING SYSTEM...THE LARGE SCALE PATTERN WILL BE
DRIVEN BY HIGH LATITUDE BLOCKING/POSITIVE HEIGHT ANOMALY SLOWLY
RETROGRADING WWD FROM GREENLAND INTO NORTH-CENTRAL CANADA. THE END
RESULT IN THIS VERY NEGATIVE AO PATTERN IS PERSISTENT TROUGHING
IN-PLACE OVER THE EASTERN U.S. THROUGH MARCH 26-27. THE 00Z LONG
RANGE BIAS-CORRECTED GEFS SUGGESTS THE -AO PATTERN BREAKS DOWN
DURING THE FINAL DAYS OF MARCH 2013.
MODELS ARE IN GOOD AGREEMENT WITH A SFC WAVE TRACKING FROM THE
LWR MS VLY NEWD INTO THE OH VLY ON MONDAY. ROBUST ISENT LIFT
AHEAD OF THE WAVE COUPLED WITH STRONG 850MB MOISTURE FLUX VIA 40KT
SWLY LLJ SHOULD PRODUCE A BROAD AREA OF WAA PRECIP EXPANDING OVER
THE AREA BY MON AFTN. THE PRECIP WILL BE OVERSPREADING A
RETREATING COLD SECTOR WHICH SHOULD LEAD TO A PERIOD OF SNOW
AT THE ONSET...FOLLOWED BY A TRANSITION TO SLEET/FREEZING RAIN OR
PLAIN RAIN AS WARM AIR SURGES IN ALOFT AHEAD OF THE COLD FRONT.
GIVEN THE COMPLEXITY/UNCERTAINTY ASSOCIATED WITH THERMAL
PROFILES...THE DAY 3 WINTER WX GRIDS WERE DERIVED FROM WPC
GUIDANCE WHICH USED A GENERAL CONSENSUS BLEND OF THE OPERATIONAL
GFS/ECMWF AND THEIR RESPECTIVE MEANS FOR BOTH QPF AND PTYPE.
SNOWFALL PROBABILITY CHARTS DERIVED FROM THE WPC INTERNAL WWD AND
MULTI-MODEL/ENSEMBLE DISTRIBUTION SHOW THE BEST CHANCE FOR LGT TO
PERHAPS MOD ACCUMS OVER THE INTERIOR N-CENTRAL MTNS. OTHER FACTORS
TO CONSIDER FOR ACCUMS INCLUDE DIURNAL/CLIMO EFFECTS...MARGINAL
BLYR TEMPS AND ELEVATION.
NW FLOW UNDER COLD CYCLONIC FLOW ALOFT WITH SLOW-MOVING H5 LOW
SLOWLY MIGRATING INTO THE MARITIMES WILL KEEP LGT PCPN IN THE
FCST OVER THE FAVORED LAKE-EFFECT/UPSLOPE AREAS. NO SIGN OF "WARM"
AIR ON THE IMMEDIATE HORIZON WITH BELOW NORMAL TEMPS EXPECTED
THROUGH THE UPCOMING WEEK.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
LOW PRESSURE WILL TRACK SOUTH OF THE AREA LATER TODAY FOLLOWED BY
HIGH PRESSURE FOR TONIGHT AND EARLY SUNDAY.
THE STORM TODAY IS BRINGING WIDESPREAD IFR/LIFR WITH SNOW...WHICH
WILL MIX WITH RAIN OVER FAR SOUTHERN AREAS THIS AFTERNOON. PRECIP
WILL BEGIN TO TAPER OFF DURING THE LAST HALF OF THE
AFTERNOON...BUT LOW CIGS WILL LINGER INTO EARLY TONIGHT WITH SOME
IMPROVEMENT EXPECTED BY SUNDAY.
WE RUN THE RISK OF SOME FREEZING DRIZZLE LINGERING FOR THE FIRST
HALF OF THE OVERNIGHT. THE GREATEST RISK OF THIS WILL BE OVER THE
RIDGES. JST PROBABLY HAS THE BIGGEST CHANCE OF OBSERVING THE
FREEZING PRECIP...UNTIL CONDITIONS DRY OUT LATER AT NIGHT.
OUTLOOK...
SUN...MAINLY VFR. CONDITIONS MAY LOWER LATE OVER THE SOUTHWEST.
SUN NIGHT-TUES...WIDESPREAD IFR AND LIFR WITH A WINTRY MIX AND
LOW CIGS.
WED-THU...NW FLOW...MVFR NW - VFR SE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...GARTNER/STEINBUGL
AVIATION...LA CORTE/STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1241 PM EDT SAT MAR 16 2013
.SYNOPSIS...
A WAVE OF LOW PRESSURE WILL TRACK TO THE SOUTH OF THE MASON-
DIXON LINE THIS AFTERNOON...BEFORE SLIDING OFF THE VIRGINIA COAST
TONIGHT. HIGH PRESSURE WILL DRIFT OUT OF THE GREAT LAKES ON SUNDAY
AND RETREAT INTO NEW ENGLAND SUNDAY NIGHT. A COMPLEX FRONTAL
SYSTEM WILL THEN IMPACT THE REGION EARLY NEXT WEEK.
HIGH LATITUDE BLOCKING WILL KEEP AN UPPER TROUGH OVER THE
EASTERN U.S. DURING THE SECOND HALF OF NEXT WEEK WITH BELOW NORMAL
TEMPERATURES LIKELY CONTINUING THROUGH THE START OF ASTRONOMICAL
SPRING.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE FAST MOVING LOW AMPLITUDE UPPER WAVE AND WEAK SURFACE LOW WILL
CONTINUE TO RACE ESE ACROSS THE REGION TODAY. LIGHT-MODERATE SNOW
HAS BEEN FALLING SINCE EARLY TODAY WITH SEVERAL REPORTS IN THE 1
TO 2 INCH RANGE...WITH SOME AREAS WITH SLIGHTLY HIGHER NUMBERS
REPORTING IN.
THE THINKING HAS NOT CHANGED SIGNIFICANTLY...WITH MOISTURE FROM
THE SYSTEM REMAINING LIMITED. BUT MID LEVEL DYNAMICS ARE
IMPRESSIVE WITH A TIGHT THERMAL GRADIENT FORECAST TO TIGHTEN IN
TIME. RUC SHOWS POTENT LOW-MID LEVEL FRONTOGENETIC FORCING WITH
THE BACK EDGE ENTERING WESTERN PA AS OF ID DAY. THERE IS ALSO AN
EROSION OF STABILITY EXPECTED THROUGH MID AFTERNOON...WITH THE
ZERO LI LINE POKING INTO FAR SWRN PA. THE FCST PARAMETERS AND
RADAR SUPPORT THE IDEA THAT DESPITE LIMITED MOISTURE...THE
ATMOSPHERE IS WORKING ABOUT AS EFFICIENTLY AS POSSIBLE IN
CRANKING OUT PRECIPITATION.
THE MAIN ISSUES TODAY REMAIN THE MARGINAL SURFACE TEMPERATURES
AND THE EFFECT OF THE RELATIVELY HIGH MID MARCH SUN ANGLES ON THE
FALLING SNOW WHICH IS EXPECTED OVER ABOUT THE NORTHERN HALF OF THE
AREA. AT THIS TIME OF YEAR...DURING THE DAY...IT USUALLY NEEDS TO
SNOW PRETTY HARD FOR ACCUMULATIONS TO OCCUR. HOURLY AND MAX SFC
TEMPS IN THIS CORRIDOR WILL BE IN THE UPPER 20S TO LOWER 30S
EXCEPT FOR THE MIDDLE AND WEST BRANCH PORTION OF THE SUSQ
VALLEY...WHERE TEMPS WILL BE NEARLY STEADY BETWEEN 33-36F TODAY.
THIS WOULD SUGGEST THAT MOST ACCUMS WILL BE LIMITED TO MAINLY
GRASSY AREAS...WHICH ALREADY WHAT WE ARE OBSERVING OUT THE WINDOW
HERE AT THE OFFICE. HOWEVER...UNTREATED ROADS WILL LIKELY BECOME
SLICK WHERE SNOWFALL RATES THAT MAY APPROACH 1/2 INCH OR MORE PER
HOUR AT TIMES ARE OBSERVED.
ACROSS THE SOUTHERN TIER...WARMER BLYR TEMPS WITH SFC TEMPS IN THE
UPPER 30S TO LOWER 40S WILL LEAD TO SNOW...POSSIBLY MIXED RAIN
AT TIMES. THE WARM SKIN TEMPS WILL KEEP SNOW ACCUMS MINIMAL.
PRECIP WILL WIND DOWN RAPIDLY LATER TODAY AND THIS EVENING AS THE
FORCING ASSOCIATED WITH THE WAVE SLIDES BY AND HIGH PRESSURE
PRESSES IN FROM THE NORTH. CLOUDS WILL BE SLOW TO SCOUR OUT
HOWEVER...SO THERE WILL BE SOME CONCERN FOR SPOTTY FREEZING
DRIZZLE INTO THE WEE HOURS. THIS WILL NEED TO BE MONITORED BY THE
EVE SHIFT.
&&
.SHORT TERM /SUNDAY/...
DIFFERENCES IN THE SHORT RANGE GUIDANCE BEGIN TO SHOW UP AS EARLY
AS DAY TWO WITH THE GFS SHOWING PRECIP ENTERING THE FAR SRN TIER
AS EARLY AS SUNDAY AFTERNOON...WHILE THE NAM IS DRY THROUGH 00Z
MONDAY. THE OLD ECMWF AND CMC ARE IN LINE WITH THE NEW NAM. THE
09Z SREF AND 06Z GEFS LEAN CLOSER TO THE NEW GFS WITH THE
REINTRODUCING OF LIGHT PRECIP OVER THE FAR SOUTH AFTER 18Z.
WITH A COLD HIGH SETTING UP SHOP TO OUR NE..WE LOOK TO BE SETTING
UP FOR A CLASSIC WINTRY MIX SETUP FOR MUCH OF OUR AREA WITH THE
APPROACH OF THE NEXT FRONTAL SYSTEM.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
1030MB HIGH PRES RETREATING INTO NRN NEW ENGLAND WITH WIDESPREAD
COLD AIR DAMMING INITIALLY ENTRENCHED ALONG/EAST OF THE ALLEGHENIES
WILL SET THE STAGE FOR A LATE-SEASON MIXED PRECIP EVENT ON
MONDAY...AS A STRONG EAST-WEST FRONTAL SYSTEM LIFTS NORTHEAST FROM
THE OHIO VALLEY AND MERGES WITH A POTENT SHORTWAVE AND ASSOCIATED
COLD FRONT SWEEPING EWD INTO THE MID-ATLC AND NORTHEAST STATES.
BEHIND THE DEPARTING SYSTEM...THE LARGE SCALE PATTERN WILL BE
DRIVEN BY HIGH LATITUDE BLOCKING/POSITIVE HEIGHT ANOMALY SLOWLY
RETROGRADING WWD FROM GREENLAND INTO NORTH-CENTRAL CANADA. THE END
RESULT IN THIS VERY NEGATIVE AO PATTERN IS PERSISTENT TROUGHING
IN-PLACE OVER THE EASTERN U.S. THROUGH MARCH 26-27. THE 00Z LONG
RANGE BIAS-CORRECTED GEFS SUGGESTS THE -AO PATTERN BREAKS DOWN
DURING THE FINAL DAYS OF MARCH 2013.
MODELS ARE IN GOOD AGREEMENT WITH A SFC WAVE TRACKING FROM THE
LWR MS VLY NEWD INTO THE OH VLY ON MONDAY. ROBUST ISENT LIFT
AHEAD OF THE WAVE COUPLED WITH STRONG 850MB MOISTURE FLUX VIA 40KT
SWLY LLJ SHOULD PRODUCE A BROAD AREA OF WAA PRECIP EXPANDING OVER
THE AREA BY MON AFTN. THE PRECIP WILL BE OVERSPREADING A
RETREATING COLD SECTOR WHICH SHOULD LEAD TO A PERIOD OF SNOW
AT THE ONSET...FOLLOWED BY A TRANSITION TO SLEET/FREEZING RAIN OR
PLAIN RAIN AS WARM AIR SURGES IN ALOFT AHEAD OF THE COLD FRONT.
GIVEN THE COMPLEXITY/UNCERTAINTY ASSOCIATED WITH THERMAL
PROFILES...THE DAY 3 WINTER WX GRIDS WERE DERIVED FROM WPC
GUIDANCE WHICH USED A GENERAL CONSENSUS BLEND OF THE OPERATIONAL
GFS/ECMWF AND THEIR RESPECTIVE MEANS FOR BOTH QPF AND PTYPE.
SNOWFALL PROBABILITY CHARTS DERIVED FROM THE WPC INTERNAL WWD AND
MULTI-MODEL/ENSEMBLE DISTRIBUTION SHOW THE BEST CHANCE FOR LGT TO
PERHAPS MOD ACCUMS OVER THE INTERIOR N-CENTRAL MTNS. OTHER FACTORS
TO CONSIDER FOR ACCUMS INCLUDE DIURNAL/CLIMO EFFECTS...MARGINAL
BLYR TEMPS AND ELEVATION.
NW FLOW UNDER COLD CYCLONIC FLOW ALOFT WITH SLOW-MOVING H5 LOW
SLOWLY MIGRATING INTO THE MARITIMES WILL KEEP LGT PCPN IN THE
FCST OVER THE FAVORED LAKE-EFFECT/UPSLOPE AREAS. NO SIGN OF "WARM"
AIR ON THE IMMEDIATE HORIZON WITH BELOW NORMAL TEMPS EXPECTED
THROUGH THE UPCOMING WEEK.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
LOW PRESSURE WILL TRACK SOUTH OF THE AREA LATER TODAY FOLLOWED BY
HIGH PRESSURE FOR TONIGHT AND EARLY SUNDAY.
THE STORM TODAY IS BRINGING WIDESPREAD IFR/LIFR WITH SNOW...WHICH
WILL MIX WITH RAIN OVER FAR SOUTHERN AREAS THIS AFTERNOON. PRECIP
WILL BEGIN TO TAPER OFF DURING THE LAST HALF OF THE
AFTERNOON...BUT LOW CIGS WILL LINGER INTO EARLY TONIGHT WITH SOME
IMPROVEMENT EXPECTED BY SUNDAY.
WE RUN THE RISK OF SOME FREEZING DRIZZLE LINGERING FOR THE FIRST
HALF OF THE OVERNIGHT. THE GREATEST RISK OF THIS WILL BE OVER THE
RIDGES. JST PROBABLY HAS THE BIGGEST CHANCE OF OBSERVING THE
FREEZING PRECIP...UNTIL CONDITIONS DRY OUT LATER AT NIGHT.
OUTLOOK...
SUN...MAINLY VFR. CONDITIONS MAY LOWER LATE OVER THE SOUTHWEST.
SUN NIGHT-TUES...WIDESPREAD IFR AND LIFR WITH A WINTRY MIX AND
LOW CIGS.
WED-THU...NW FLOW...MVFR NW - VFR SE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...STEINBUGL
AVIATION...LA CORTE/STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1239 PM EDT SAT MAR 16 2013
.SYNOPSIS...
A WAVE OF LOW PRESSURE WILL TRACK TO THE SOUTH OF THE MASON-
DIXON LINE THIS AFTERNOON...BEFORE SLIDING OFF THE VIRGINIA COAST
TONIGHT. HIGH PRESSURE WILL DRIFT OUT OF THE GREAT LAKES ON SUNDAY
AND RETREAT INTO NEW ENGLAND SUNDAY NIGHT. A COMPLEX FRONTAL
SYSTEM WILL THEN IMPACT THE REGION EARLY NEXT WEEK.
HIGH LATITUDE BLOCKING WILL KEEP AN UPPER TROUGH OVER THE
EASTERN U.S. DURING THE SECOND HALF OF NEXT WEEK WITH BELOW NORMAL
TEMPERATURES LIKELY CONTINUING THROUGH THE START OF ASTRONOMICAL
SPRING.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE FAST MOVING LOW AMPLITUDE UPPER WAVE AND WEAK SURFACE LOW WILL
CONTINUE TO RACE ESE ACROSS THE REGION TODAY. LIGHT-MODERATE SNOW
HAS BEEN FALLING SINCE EARLY TODAY WITH SEVERAL REPORTS IN THE 1
TO 2 INCH RANGE...WITH SOME AREAS WITH SLIGHTLY HIGHER NUMBERS
REPORTING IN.
THE THINKING HAS NOT CHANGED SIGNIFICANTLY...WITH MOISTURE FROM
THE SYSTEM REMAINING LIMITED. BUT MID LEVEL DYNAMICS ARE
IMPRESSIVE WITH A TIGHT THERMAL GRADIENT FORECAST TO TIGHTEN IN
TIME. RUC SHOWS POTENT LOW-MID LEVEL FRONTOGENETIC FORCING WITH
THE BACK EDGE ENTERING WESTERN PA AS OF ID DAY. THERE IS ALSO AN
EROSION OF STABILITY EXPECTED THROUGH MID AFTERNOON...WITH THE
ZERO LI LINE POKING INTO FAR SWRN PA. THE FCST PARAMETERS AND
RADAR SUPPORT THE IDEA THAT DESPITE LIMITED MOISTURE...THE
ATMOSPHERE IS WORKING ABOUT AS EFFICIENTLY AS POSSIBLE IN
CRANKING OUT PRECIPITATION.
THE MAIN ISSUES TODAY REMAIN THE MARGINAL SURFACE TEMPERATURES
AND THE EFFECT OF THE RELATIVELY HIGH MID MARCH SUN ANGLES ON THE
FALLING SNOW WHICH IS EXPECTED OVER ABOUT THE NORTHERN HALF OF THE
AREA. AT THIS TIME OF YEAR...DURING THE DAY...IT USUALLY NEEDS TO
SNOW PRETTY HARD FOR ACCUMULATIONS TO OCCUR. HOURLY AND MAX SFC
TEMPS IN THIS CORRIDOR WILL BE IN THE UPPER 20S TO LOWER 30S
EXCEPT FOR THE MIDDLE AND WEST BRANCH PORTION OF THE SUSQ
VALLEY...WHERE TEMPS WILL BE NEARLY STEADY BETWEEN 33-36F TODAY.
THIS WOULD SUGGEST THAT MOST ACCUMS WILL BE LIMITED TO MAINLY
GRASSY AREAS...WHICH ALREADY WHAT WE ARE OBSERVING OUT THE WINDOW
HERE AT THE OFFICE. HOWEVER...UNTREATED ROADS WILL LIKELY BECOME
SLICK WHERE SNOWFALL RATES THAT MAY APPROACH 1/2 INCH OR MORE PER
HOUR AT TIMES ARE OBSERVED.
ACROSS THE SOUTHERN TIER...WARMER BLYR TEMPS WITH SFC TEMPS IN THE
UPPER 30S TO LOWER 40S WILL LEAD TO SNOW...POSSIBLY MIXED RAIN
AT TIMES. THE WARM SKIN TEMPS WILL KEEP SNOW ACCUMS MINIMAL.
PRECIP WILL WIND DOWN RAPIDLY LATER TODAY AND THIS EVENING AS THE
FORCING ASSOCIATED WITH THE WAVE SLIDES BY AND HIGH PRESSURE
PRESSES IN FROM THE NORTH. CLOUDS WILL BE SLOW TO SCOUR OUT
HOWEVER...SO THERE WILL BE SOME CONCERN FOR SPOTTY FREEZING
DRIZZLE INTO THE WEE HOURS. THIS WILL NEED TO BE MONITORED BY THE
EVE SHIFT.
&&
.SHORT TERM /SUNDAY/...
DIFFERENCES IN THE SHORT RANGE GUIDANCE BEGIN TO SHOW UP AS EARLY
AS DAY TWO WITH THE GFS SHOWING PRECIP ENTERING THE FAR SRN TIER
AS EARLY AS SUNDAY AFTERNOON...WHILE THE NAM IS DRY THROUGH 00Z
MONDAY. THE OLD ECMWF AND CMC ARE IN LINE WITH THE NEW NAM. THE
09Z SREF AND 06Z GEFS LEAN CLOSER TO THE NEW GFS WITH THE
REINTRODUCING OF LIGHT PRECIP OVER THE FAR SOUTH AFTER 18Z.
WITH A COLD HIGH SETTING UP SHOP TO OUR NE..WE LOOK TO BE SETTING
UP FOR A CLASSIC WINTRY MIX SETUP FOR MUCH OF OUR AREA WITH THE
APPROACH OF THE NEXT FRONTAL SYSTEM.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
1030MB HIGH PRES RETREATING INTO NRN NEW ENGLAND WITH WIDESPREAD
COLD AIR DAMMING INITIALLY ENTRENCHED ALONG/EAST OF THE ALLEGHENIES
WILL SET THE STAGE FOR A LATE-SEASON MIXED PRECIP EVENT ON
MONDAY...AS A STRONG EAST-WEST FRONTAL SYSTEM LIFTS NORTHEAST FROM
THE OHIO VALLEY AND MERGES WITH A POTENT SHORTWAVE AND ASSOCIATED
COLD FRONT SWEEPING EWD INTO THE MID-ATLC AND NORTHEAST STATES.
BEHIND THE DEPARTING SYSTEM...THE LARGE SCALE PATTERN WILL BE
DRIVEN BY HIGH LATITUDE BLOCKING/POSITIVE HEIGHT ANOMALY SLOWLY
RETROGRADING WWD FROM GREENLAND INTO NORTH-CENTRAL CANADA. THE END
RESULT IN THIS VERY NEGATIVE AO PATTERN IS PERSISTENT TROUGHING
IN-PLACE OVER THE EASTERN U.S. THROUGH MARCH 26-27. THE 00Z LONG
RANGE BIAS-CORRECTED GEFS SUGGESTS THE -AO PATTERN BREAKS DOWN
DURING THE FINAL DAYS OF MARCH 2013.
MODELS ARE IN GOOD AGREEMENT WITH A SFC WAVE TRACKING FROM THE
LWR MS VLY NEWD INTO THE OH VLY ON MONDAY. ROBUST ISENT LIFT
AHEAD OF THE WAVE COUPLED WITH STRONG 850MB MOISTURE FLUX VIA 40KT
SWLY LLJ SHOULD PRODUCE A BROAD AREA OF WAA PRECIP EXPANDING OVER
THE AREA BY MON AFTN. THE PRECIP WILL BE OVERSPREADING A
RETREATING COLD SECTOR WHICH SHOULD LEAD TO A PERIOD OF SNOW
AT THE ONSET...FOLLOWED BY A TRANSITION TO SLEET/FREEZING RAIN OR
PLAIN RAIN AS WARM AIR SURGES IN ALOFT AHEAD OF THE COLD FRONT.
GIVEN THE COMPLEXITY/UNCERTAINTY ASSOCIATED WITH THERMAL
PROFILES...THE DAY 3 WINTER WX GRIDS WERE DERIVED FROM WPC
GUIDANCE WHICH USED A GENERAL CONSENSUS BLEND OF THE OPERATIONAL
GFS/ECMWF AND THEIR RESPECTIVE MEANS FOR BOTH QPF AND PTYPE.
SNOWFALL PROBABILITY CHARTS DERIVED FROM THE WPC INTERNAL WWD AND
MULTI-MODEL/ENSEMBLE DISTRIBUTION SHOW THE BEST CHANCE FOR LGT TO
PERHAPS MOD ACCUMS OVER THE INTERIOR N-CENTRAL MTNS. OTHER FACTORS
TO CONSIDER FOR ACCUMS INCLUDE DIURNAL/CLIMO EFFECTS...MARGINAL
BLYR TEMPS AND ELEVATION.
NW FLOW UNDER COLD CYCLONIC FLOW ALOFT WITH SLOW-MOVING H5 LOW
SLOWLY MIGRATING INTO THE MARITIMES WILL KEEP LGT PCPN IN THE
FCST OVER THE FAVORED LAKE-EFFECT/UPSLOPE AREAS. NO SIGN OF "WARM"
AIR ON THE IMMEDIATE HORIZON WITH BELOW NORMAL TEMPS EXPECTED
THROUGH THE UPCOMING WEEK.
&&
.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
LOW PRESSURE WILL TRACK SOUTH OF THE AREA LATER TODAY FOLLOWED BY
HIGH PRESSURE FOR TONIGHT AND EARLY SUNDAY.
THE STORM TODAY IS BRINGING WIDESPREAD IFR/LIFR WITH SNOW...WHICH
WILL MIX WITH RAIN OVER FAR SOUTHERN AREAS THIS AFTERNOON. PRECIP
WILL BEGIN TO TAPER OFF DURING THE LAST HALF OF THE
AFTERNOON...BUT LOW CIGS WILL LINGER INTO EARLY TONIGHT WITH SOME
IMPROVEMENT EXPECTED BY SUNDAY.
WE RUN THE RISK OF SOME FREEZING DRIZZLE LINGERING FOR THE FIRST
HALF OF THE OVERNIGHT. THE GREATEST RISK OF THIS WILL BE OVER THE
RIDGES. JST PROBABLY HAS THE BIGGEST CHANCE OF OBSERVING THE
FREEZING PRECIP...UNTIL CONDITIONS DRY OUT LATER AT NIGHT.
OUTLOOK...
SUN...MAINLY VFR. CONDITIONS MAY LOWER LATE OVER THE SOUTHWEST.
SUN NIGHT-TUES...WIDESPREAD IFR AND LIFR WITH A WINTRY MIX AND
LOW CIGS.
WED...NW FLOW...MVFR NW - VFR SE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...STEINBUGL
AVIATION...LA CORTE/STEINBUGL
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1006 PM CDT SUN MAR 17 2013
.UPDATE...
ISSUED AT 1005 PM CDT SUN MAR 17 2013
ADJUSTED POPS THIS EVENING AND OVERNIGHT TO ACCOUNT FOR FASTER
MOVEMENT EAST OF MAIN PRE-FRONTAL PRECIPITATION BAND...AND ALSO TO
ADD IN SOME AREAS OF ISOLATED-SCATTERED SNOW SHOWERS ACROSS THE
SOUTHWEST PARTS OF THE CWA LATER TONIGHT AS THE MOISTURE CONTINUES TO
WRAP AROUND THE SOUTH SIDE OF THE LOW. WITH THE FASTER MOVEMENT...
ALSO DECREASED SOME SNOWFALL AMOUNTS FOR THE OVERNIGHT...THOUGH STILL
LOOKING AT AREAS OF 1-2 INCHES THROUGH THE ADVISORY AREA. GIVEN THE
POTENTIAL FOR ADDITIONAL SNOW SHOWERS WITH THE VERY STRONG WINDS ON
MONDAY...OPTED TO LEAVE GOING HEADLINES AS IS FOR NOW...BUT MIDNIGHT
SHIFT WILL LIKELY HAVE TO REEVALUATE AFTER GETTING A BETTER LOOK AT
THIS SNOW SHOWER POTENTIAL ON INCOMING MODEL RUNS.
UPDATE ISSUED AT 825 PM CDT SUN MAR 17 2013
COMPLEX SITUATION TONIGHT...WITH A NARROW BAND OF PRE-FRONTAL
PRECIPITATION MOVING SLOWLY EAST ACROSS SOUTHEAST SD EARLY THIS
EVENING. WEB CAMS INDICATE SOME SLUSHY ACCUMULATIONS WITHIN THE
HEAVIER AREAS OF PRECIPITATION NORTH OF I-90 WHERE SURFACE TEMPS ARE
BELOW FREEZING...WHILE AREAS SOUTH ARE SEEING LITTLE ACCUMULATION AS
OF YET. OVERALL NOT MUCH CHANGE TO GOING FORECAST...THOUGH DID SLOW
UP EASTWARD PROGRESSION OF THE SNOW BAND A BIT...WHICH ALSO RESULTED
IN DELAYING START OF ADVISORY EAST OF HIGHWAY 60 UNTIL MIDNIGHT.
WITH THE HEAVIER BAND IN EAST CENTRAL SD THIS EVENING HAVE BUMPED UP
SNOW AMOUNTS THERE SLIGHTLY...WHILE NOTCHING DOWN A LITTLE IN OUR
SOUTHEAST AREAS WHERE LITTLE SNOW IS EXPECTED THIS EVENING. STILL
GENERALLY LOOKING AT 1-3 INCHES ACROSS THE EXISTING WINTER WEATHER
ADVISORY AREA THOUGH...SO NO CHANGES TO AREA COVERED BY HEADLINES AT
THIS TIME. UPDATED GRIDS/PFM HAVE BEEN SENT...AND WILL GET A NEW ZFP
OUT SHORTLY.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 351 PM CDT SUN MAR 17 2013
STRONG FORCING PUSHING OUT INTO THE SOUTHWESTERN PORTIONS OF THE
RUSHMORE STATE AND NEBRASKA PANHANDLE. VERY STEEP LAPSE RATES IN
PLACE EVIDENCED BY A FEW LIGHTNING STRIKES ACROSS WESTERN AND NORTH
CENTRAL NEBRASKA DURING THE EARLY AND MID AFTERNOON. AHEAD OF THIS
WAVE AND DEVELOPING LOW PRESSURE...STRONG SOUTHERLY WINDS IN
PLACE...WITH ADVISORY LEVEL WINDS AT TIMES AROUND THE LOWER BRULE
AREA. THESE WINDS SHOULD EASE A BIT GOING INTO THE EARLY EVENING...
WHILE THE MAIN GRADIENT LIFTS NORTH AND EAST WITH THE MAIN CYCLONE
CENTER HEADING TOWARD EXTREME NORTHEAST SOUTH DAKOTA BY LATE EVENING.
SEVERAL BANDS OF SHOWERS IN PROCESS OF DEVELOPING ACROSS THE STATE.
HI RES MODELS...INCLUDING RAP AND SREF...HAVE TRENDED QUICKER WITH
THE PRECIP...WITH MUCH OF THE BAND EAST OF I29 BY 07-08Z...WITH
EXCEPTION OF AREA ACROSS NORTHERN CWA CLOSER TO THE MID LEVEL
CIRCULATION. NATURE OF A VERY TRANSIENT BAND WILL BE LIMITING FACTOR
ON AMOUNTS...AS WILL THE TEMPERATURES ALOFT WHICH FIGURE UP JUST A
BIT TOO WARM FOR ANY SNOW IN THE FAR SOUTHWEST...AND WILL KEEP A MIX
IN THE WORKS FROM JAMES THROUGH LOWER MISSOURI VALLEY. ONLY THE
COOLER AND SLIGHTLY DRIER AIRMASS TO THE EAST...ALONG WITH THE
DYNAMIC COOLING RESULTING FROM CONVECTIVE NATURE TO PRECIPITATION
AND SHARP LIFT FORCING WILL FORCE PRECIPITATION OVER TO SNOWFALL.
AMOUNTS SOMEWHAT DIFFICULT TO PIN DOWN GIVEN THE CONVECTIVE
NATURE...WITH AMOUNTS EXPECTED TO REFLECT THE AREAL AVERAGE...
GREATEST ACROSS PARTS OF NORTHWEST IOWA INTO SOUTHWEST MINNESOTA.
DEBATE FOR THE DAY WAS WHAT IT MIGHT TAKE TO GET BLIZZARD CONDITIONS
GIVEN THE CERTAINTY OF STRONG WINDS ON LATE SUNDAY NIGHT AND THROUGH
THE DAY MONDAY. CERTAINLY NONE OF THE REMAINING SNOW COVER WILL
CONTRIBUTE DIRECTLY...AND REALLY ONLY HAVE AROUND A TWO INCH BAND
ACROSS THE NORTHERN TIER ALONG HIGHWAY 14. STRONGEST WINDS WITH
GUSTS UPWARD OF 45 MPH AT TIMES WILL BE FROM EAST CENTRAL SOUTH
DAKOTA THROUGH SOUTHWEST MINNESOTA...SPEEDS TAPERING OFF SLIGHTLY TO
THE SOUTHWEST...BUT BALANCED SOMEWHAT BY A DEEPER MIXING PROFILE.
NOT EXPECTING A GREAT DEAL OF ADDITIONAL SNOW BY MONDAY...WITH ONLY
THE STEEP LOW LEVEL LAPSE RATES IN REACH OF FAVORABLE ICE GROWTH
RANGE SUGGESTING BANDED SHALLOW SNOW SQUALLS... SO CONTRIBUTIONS
HERE WILL BE FAIRLY MINIMAL. WHERE WE GET A COUPLE OF INCHES OVER
EXISTING SNOW/ICE COVER...WILL BE VERY CAPABLE OF SOME DECENT
LOFTING. WHERE NO SNOW COVER CURRENTLY EXISTS...WILL BE MUCH MORE
DIFFICULT TO OBTAIN ANY TRUE BLIZZARD CONDITIONS...BUT DID ADD IN A
COUPLE MORE COUNTIES TOWARD THE SOUTH IN SOUTHWEST MINNESOTA TOWARD
WHERE SOME HEAVIER SNOWFALL MAY OCCUR. FARTHER SOUTH AND WEST...
NOT EXPECTING ANY WHITEOUT CONDITIONS TO BE WIDESPREAD...BUT THAT IS
NOT SAYING THERE WOULD BE ANY WHITEOUT CONDITIONS...JUST NOT
WIDESPREAD OR LONG LASTING. CAUTION IS NEEDED...EVEN THROUGH THE
ADVISORY AREA. DID NOT POST BLIZZARD WARNING RIGHT OFF TO START...
AS STRONGER WINDS WILL COME IN LATER TONIGHT/EARLY MONDAY IN THE
WARNING AREA...SO PRECEDED WITH A WINTER WEATHER ADVISORY UP TO 09Z
IN THE BLIZZARD AREA FOR THE COMBINATION OF SNOWFALL AND SOME LESSER
POTENTIAL BLOWING SNOW WITH THE PRE-FRONTAL SOUTH/SOUTHWEST WINDS.
PROBABLY NOT A GREAT DEAL OF ROOM FOR RECOVERY IN TEMPS ON MONDAY
WITH STRONG SURGE OF COLDER AIR WRAPPING IN BEHIND SYSTEM. ONLY THE
MORE MIXED MISSOURI VALLEY WHERE LESS SNOW IS EXPECTED SHOULD SEE
ANY LESS THAN MINIMAL RECOVERY IN TEMPS.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 351 PM CDT SUN MAR 17 2013
THE SYSTEM PULLS OUT OF THE REGION ON MONDAY NIGHT...WITH GUSTY
NORTHWESTERLY WINDS DYING THROUGH THE EVENING AS A SURFACE RIDGE
SLIDES SOUTHWARD INTO THE NORTHERN PLAINS CAUSING THE GRADIENT TO
SLACKEN. TEMPERATURES ARE TRICKY THAT NIGHT...DEPENDENT ON HOW
QUICKLY THE WINDS DIE/WHERE NEW FALLEN SNOW IS IN PLACE/AND HOW MUCH
CLEARING IS REALIZED OVERNIGHT. MODEL RH TIME SECTIONS POINT TOWARD
LOWER CLOUDS CLEARING FROM WEST TO EAST DURING THE EVENING...THOUGH
MID/HIGH CLOUDS INCREASING IN THE WEST LATER AT NIGHT. AT THIS
POINT...WENT WITH LOWS AROUND ZERO ALONG HIGHWAY 14 TO THE LOWER
TEENS THROUGH THE MISSOURI RIVER CORRIDOR.
ANOTHER WEAK SHORTWAVE WILL TRACK ACROSS THE AREA ON TUESDAY...AND
MAY BE JUST ENOUGH MOISTURE AROUND TO KICK OFF A FEW FLURRIES IN OUR
EAST. TEMPERATURES WILL STILL BE MUCH BELOW NORMAL FOR THIS TIME OF
YEAR WITH HIGHS GENERALLY IN THE 20S NORTH TO 30S SOUTH. FARTHER
INTO THE EXTENDED...A BROAD UPPER LEVEL LOW OVER THE EASTERN
PORTIONS OF THE COUNTRY WILL KEEP OUR AREA IN A NORTHWESTERLY UPPER
LEVEL FLOW FOR WEDNESDAY AND EARLY THURSDAY BEFORE THE NEXT
SHORTWAVE BEGINS TO ENCROACH ON THE AREA IN THE LATE THURSDAY TO
FRIDAY TIME FRAME. MODELS CONTINUE TO DIFFER ON HOW THEY HANDLE THIS
SYSTEM...WITH BOTH THE ECMWF AND GEM KEEPING IT FARTHER TO THE
SOUTH..AND THE GFS PERSISTING WITH A MORE NORTHERLY SOLUTION. SOME
CONSENSUS...WEIGHED MORE HEAVILY TO THE MORE SOUTHERLY SOLUTION
WOULD BRING A CHANCE OF LIGHT SNOW TO OUR SOUTHWEST DURING THIS TIME
FRAME. MODELS KEEP MUCH BELOW NORMAL THERMAL PROFILES IN PLACE
ACROSS THE REGION THROUGH NEXT WEEKEND...WITH HIGHS GENERALLY 20S AND
30S...AND LOWS SINGLE DIGITS AND TEENS EARLY ON...TO TEENS AND 20S
LATE IN THE PERIOD.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 800 PM CDT SUN MAR 17 2013
BAND OF PRECIPITATION IN EASTERN SD LEADING THE COLD FRONT THAT IS
WORKING THROUGH WESTERN SD AT 00Z. ALONG AND NORTH OF I-90 IT IS ALL
SNOW...WITH ALL RAIN TO THE SOUTH IN THE WARMER AIR. HAVE MAINLY
SEEN MVFR VISIBILITIES OF 2-4 MILES IN THE SNOW...BUT KHON DID
BRIEFLY DROP TO AROUND 1 MILE IN HEAVIER SNOW WITH STRONGER WINDS
EARLY THIS EVENING. WIND SPEEDS HAVE DIMINISHED TO 20-30 MPH FOR ALL
AREAS AT SUNSET...AND WILL STAY IN THAT RANGE UNTIL THE LOW PASSES
LATE TONIGHT AND WINDS SWING AROUND TO THE NORTHWEST FOR MONDAY.
WIDESPREAD MVFR CEILINGS OF 2000-3000 FEET...DROPPING AT TIMES TO
1000 FEET IN THE HEAVIER SNOW BANDS TONIGHT. FOR MONDAY...SOUTHERN
AREAS ALONG MISSOURI RIVER WILL SEE SOME CLEARING AS THE DAY GOES ON
WHILE THE NORTH REMAINS IN MVFR CEILINGS AND VISIBILITIES THROUGH AT
LEAST 18Z WITH THE POTENTIAL FOR 1 MILE OR LESS VISIBILITIES BRIEFLY
IN BLOWING SNOW ALONG WITH SCATTERED SNOW SHOWERS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 7 PM CDT MONDAY FOR SDZ038-054>056-
062-067.
WIND ADVISORY FROM 4 AM TO 7 PM CDT MONDAY FOR SDZ050-052-053-
057>061-063>066-068>071.
WINTER WEATHER ADVISORY UNTIL 4 AM CDT MONDAY FOR SDZ039-040.
BLIZZARD WARNING FROM 4 AM TO 7 PM CDT MONDAY FOR SDZ039-040.
MN...WINTER WEATHER ADVISORY UNTIL 7 PM CDT MONDAY FOR MNZ089-097-098.
WINTER WEATHER ADVISORY UNTIL 4 AM CDT MONDAY FOR MNZ071-072-080-
081.
BLIZZARD WARNING FROM 4 AM TO 7 PM CDT MONDAY FOR MNZ071-072-080-
081.
WINTER WEATHER ADVISORY UNTIL 7 PM CDT MONDAY FOR MNZ090.
IA...WINTER WEATHER ADVISORY UNTIL 7 PM CDT MONDAY FOR IAZ001-012.
WIND ADVISORY FROM 4 AM TO 7 PM CDT MONDAY FOR IAZ031.
WINTER WEATHER ADVISORY UNTIL 7 PM CDT MONDAY FOR IAZ002-003-013-
014-020>022-032.
NE...WIND ADVISORY FROM 4 AM TO 7 PM CDT MONDAY FOR NEZ013-014.
&&
$$
UPDATE...JH
SHORT TERM...CHAPMAN
LONG TERM...JM
AVIATION...GILLISPIE
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
826 PM CDT SUN MAR 17 2013
.UPDATE...
ISSUED AT 825 PM CDT SUN MAR 17 2013
COMPLEX SITUATION TONIGHT...WITH A NARROW BAND OF PRE-FRONTAL
PRECIPITATION MOVING SLOWLY EAST ACROSS SOUTHEAST SD EARLY THIS
EVENING. WEB CAMS INDICATE SOME SLUSHY ACCUMULATIONS WITHIN THE
HEAVIER AREAS OF PRECIPITATION NORTH OF I-90 WHERE SURFACE TEMPS ARE
BELOW FREEZING...WHILE AREAS SOUTH ARE SEEING LITTLE ACCUMULATION AS
OF YET. OVERALL NOT MUCH CHANGE TO GOING FORECAST...THOUGH DID SLOW
UP EASTWARD PROGRESSION OF THE SNOW BAND A BIT...WHICH ALSO RESULTED
IN DELAYING START OF ADVISORY EAST OF HIGHWAY 60 UNTIL MIDNIGHT.
WITH THE HEAVIER BAND IN EAST CENTRAL SD THIS EVENING HAVE BUMPED UP
SNOW AMOUNTS THERE SLIGHTLY...WHILE NOTCHING DOWN A LITTLE IN OUR
SOUTHEAST AREAS WHERE LITTLE SNOW IS EXPECTED THIS EVENING. STILL
GENERALLY LOOKING AT 1-3 INCHES ACROSS THE EXISTING WINTER WEATHER
ADVISORY AREA THOUGH...SO NO CHANGES TO AREA COVERED BY HEADLINES AT
THIS TIME. UPDATED GRIDS/PFM HAVE BEEN SENT...AND WILL GET A NEW ZFP
OUT SHORTLY.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 351 PM CDT SUN MAR 17 2013
STRONG FORCING PUSHING OUT INTO THE SOUTHWESTERN PORTIONS OF THE
RUSHMORE STATE AND NEBRASKA PANHANDLE. VERY STEEP LAPSE RATES IN
PLACE EVIDENCED BY A FEW LIGHTNING STRIKES ACROSS WESTERN AND NORTH
CENTRAL NEBRASKA DURING THE EARLY AND MID AFTERNOON. AHEAD OF THIS
WAVE AND DEVELOPING LOW PRESSURE...STRONG SOUTHERLY WINDS IN
PLACE...WITH ADVISORY LEVEL WINDS AT TIMES AROUND THE LOWER BRULE
AREA. THESE WINDS SHOULD EASE A BIT GOING INTO THE EARLY EVENING...
WHILE THE MAIN GRADIENT LIFTS NORTH AND EAST WITH THE MAIN CYCLONE
CENTER HEADING TOWARD EXTREME NORTHEAST SOUTH DAKOTA BY LATE EVENING.
SEVERAL BANDS OF SHOWERS IN PROCESS OF DEVELOPING ACROSS THE STATE.
HI RES MODELS...INCLUDING RAP AND SREF...HAVE TRENDED QUICKER WITH
THE PRECIP...WITH MUCH OF THE BAND EAST OF I29 BY 07-08Z...WITH
EXCEPTION OF AREA ACROSS NORTHERN CWA CLOSER TO THE MID LEVEL
CIRCULATION. NATURE OF A VERY TRANSIENT BAND WILL BE LIMITING FACTOR
ON AMOUNTS...AS WILL THE TEMPERATURES ALOFT WHICH FIGURE UP JUST A
BIT TOO WARM FOR ANY SNOW IN THE FAR SOUTHWEST...AND WILL KEEP A MIX
IN THE WORKS FROM JAMES THROUGH LOWER MISSOURI VALLEY. ONLY THE
COOLER AND SLIGHTLY DRIER AIRMASS TO THE EAST...ALONG WITH THE
DYNAMIC COOLING RESULTING FROM CONVECTIVE NATURE TO PRECIPITATION
AND SHARP LIFT FORCING WILL FORCE PRECIPITATION OVER TO SNOWFALL.
AMOUNTS SOMEWHAT DIFFICULT TO PIN DOWN GIVEN THE CONVECTIVE
NATURE...WITH AMOUNTS EXPECTED TO REFLECT THE AREAL AVERAGE...
GREATEST ACROSS PARTS OF NORTHWEST IOWA INTO SOUTHWEST MINNESOTA.
DEBATE FOR THE DAY WAS WHAT IT MIGHT TAKE TO GET BLIZZARD CONDITIONS
GIVEN THE CERTAINTY OF STRONG WINDS ON LATE SUNDAY NIGHT AND THROUGH
THE DAY MONDAY. CERTAINLY NONE OF THE REMAINING SNOW COVER WILL
CONTRIBUTE DIRECTLY...AND REALLY ONLY HAVE AROUND A TWO INCH BAND
ACROSS THE NORTHERN TIER ALONG HIGHWAY 14. STRONGEST WINDS WITH
GUSTS UPWARD OF 45 MPH AT TIMES WILL BE FROM EAST CENTRAL SOUTH
DAKOTA THROUGH SOUTHWEST MINNESOTA...SPEEDS TAPERING OFF SLIGHTLY TO
THE SOUTHWEST...BUT BALANCED SOMEWHAT BY A DEEPER MIXING PROFILE.
NOT EXPECTING A GREAT DEAL OF ADDITIONAL SNOW BY MONDAY...WITH ONLY
THE STEEP LOW LEVEL LAPSE RATES IN REACH OF FAVORABLE ICE GROWTH
RANGE SUGGESTING BANDED SHALLOW SNOW SQUALLS... SO CONTRIBUTIONS
HERE WILL BE FAIRLY MINIMAL. WHERE WE GET A COUPLE OF INCHES OVER
EXISTING SNOW/ICE COVER...WILL BE VERY CAPABLE OF SOME DECENT
LOFTING. WHERE NO SNOW COVER CURRENTLY EXISTS...WILL BE MUCH MORE
DIFFICULT TO OBTAIN ANY TRUE BLIZZARD CONDITIONS...BUT DID ADD IN A
COUPLE MORE COUNTIES TOWARD THE SOUTH IN SOUTHWEST MINNESOTA TOWARD
WHERE SOME HEAVIER SNOWFALL MAY OCCUR. FARTHER SOUTH AND WEST...
NOT EXPECTING ANY WHITEOUT CONDITIONS TO BE WIDESPREAD...BUT THAT IS
NOT SAYING THERE WOULD BE ANY WHITEOUT CONDITIONS...JUST NOT
WIDESPREAD OR LONG LASTING. CAUTION IS NEEDED...EVEN THROUGH THE
ADVISORY AREA. DID NOT POST BLIZZARD WARNING RIGHT OFF TO START...
AS STRONGER WINDS WILL COME IN LATER TONIGHT/EARLY MONDAY IN THE
WARNING AREA...SO PRECEDED WITH A WINTER WEATHER ADVISORY UP TO 09Z
IN THE BLIZZARD AREA FOR THE COMBINATION OF SNOWFALL AND SOME LESSER
POTENTIAL BLOWING SNOW WITH THE PRE-FRONTAL SOUTH/SOUTHWEST WINDS.
PROBABLY NOT A GREAT DEAL OF ROOM FOR RECOVERY IN TEMPS ON MONDAY
WITH STRONG SURGE OF COLDER AIR WRAPPING IN BEHIND SYSTEM. ONLY THE
MORE MIXED MISSOURI VALLEY WHERE LESS SNOW IS EXPECTED SHOULD SEE
ANY LESS THAN MINIMAL RECOVERY IN TEMPS.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 351 PM CDT SUN MAR 17 2013
THE SYSTEM PULLS OUT OF THE REGION ON MONDAY NIGHT...WITH GUSTY
NORTHWESTERLY WINDS DYING THROUGH THE EVENING AS A SURFACE RIDGE
SLIDES SOUTHWARD INTO THE NORTHERN PLAINS CAUSING THE GRADIENT TO
SLACKEN. TEMPERATURES ARE TRICKY THAT NIGHT...DEPENDENT ON HOW
QUICKLY THE WINDS DIE/WHERE NEW FALLEN SNOW IS IN PLACE/AND HOW MUCH
CLEARING IS REALIZED OVERNIGHT. MODEL RH TIME SECTIONS POINT TOWARD
LOWER CLOUDS CLEARING FROM WEST TO EAST DURING THE EVENING...THOUGH
MID/HIGH CLOUDS INCREASING IN THE WEST LATER AT NIGHT. AT THIS
POINT...WENT WITH LOWS AROUND ZERO ALONG HIGHWAY 14 TO THE LOWER
TEENS THROUGH THE MISSOURI RIVER CORRIDOR.
ANOTHER WEAK SHORTWAVE WILL TRACK ACROSS THE AREA ON TUESDAY...AND
MAY BE JUST ENOUGH MOISTURE AROUND TO KICK OFF A FEW FLURRIES IN OUR
EAST. TEMPERATURES WILL STILL BE MUCH BELOW NORMAL FOR THIS TIME OF
YEAR WITH HIGHS GENERALLY IN THE 20S NORTH TO 30S SOUTH. FARTHER
INTO THE EXTENDED...A BROAD UPPER LEVEL LOW OVER THE EASTERN
PORTIONS OF THE COUNTRY WILL KEEP OUR AREA IN A NORTHWESTERLY UPPER
LEVEL FLOW FOR WEDNESDAY AND EARLY THURSDAY BEFORE THE NEXT
SHORTWAVE BEGINS TO ENCROACH ON THE AREA IN THE LATE THURSDAY TO
FRIDAY TIME FRAME. MODELS CONTINUE TO DIFFER ON HOW THEY HANDLE THIS
SYSTEM...WITH BOTH THE ECMWF AND GEM KEEPING IT FARTHER TO THE
SOUTH..AND THE GFS PERSISTING WITH A MORE NORTHERLY SOLUTION. SOME
CONSENSUS...WEIGHED MORE HEAVILY TO THE MORE SOUTHERLY SOLUTION
WOULD BRING A CHANCE OF LIGHT SNOW TO OUR SOUTHWEST DURING THIS TIME
FRAME. MODELS KEEP MUCH BELOW NORMAL THERMAL PROFILES IN PLACE
ACROSS THE REGION THROUGH NEXT WEEKEND...WITH HIGHS GENERALLY 20S AND
30S...AND LOWS SINGLE DIGITS AND TEENS EARLY ON...TO TEENS AND 20S
LATE IN THE PERIOD.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 800 PM CDT SUN MAR 17 2013
BAND OF PRECIPITATION IN EASTERN SD LEADING THE COLD FRONT THAT IS
WORKING THROUGH WESTERN SD AT 00Z. ALONG AND NORTH OF I-90 IT IS ALL
SNOW...WITH ALL RAIN TO THE SOUTH IN THE WARMER AIR. HAVE MAINLY
SEEN MVFR VISIBILITIES OF 2-4 MILES IN THE SNOW...BUT KHON DID
BRIEFLY DROP TO AROUND 1 MILE IN HEAVIER SNOW WITH STRONGER WINDS
EARLY THIS EVENING. WIND SPEEDS HAVE DIMINISHED TO 20-30 MPH FOR ALL
AREAS AT SUNSET...AND WILL STAY IN THAT RANGE UNTIL THE LOW PASSES
LATE TONIGHT AND WINDS SWING AROUND TO THE NORTHWEST FOR MONDAY.
WIDESPREAD MVFR CEILINGS OF 2000-3000 FEET...DROPPING AT TIMES TO
1000 FEET IN THE HEAVIER SNOW BANDS TONIGHT. FOR MONDAY...SOUTHERN
AREAS ALONG MISSOURI RIVER WILL SEE SOME CLEARING AS THE DAY GOES ON
WHILE THE NORTH REMAINS IN MVFR CEILINGS AND VISIBILITIES THROUGH AT
LEAST 18Z WITH THE POTENTIAL FOR 1 MILE OR LESS VISIBILITIES BRIEFLY
IN BLOWING SNOW ALONG WITH SCATTERED SNOW SHOWERS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 7 PM CDT MONDAY FOR SDZ038-054>056-
062-067.
WIND ADVISORY FROM 4 AM TO 7 PM CDT MONDAY FOR SDZ050-052-053-
057>061-063>066-068>071.
WINTER WEATHER ADVISORY UNTIL 4 AM CDT MONDAY FOR SDZ039-040.
BLIZZARD WARNING FROM 4 AM TO 7 PM CDT MONDAY FOR SDZ039-040.
MN...WINTER WEATHER ADVISORY UNTIL 7 PM CDT MONDAY FOR MNZ089-097-098.
WINTER WEATHER ADVISORY UNTIL 4 AM CDT MONDAY FOR MNZ071-072-080-
081.
BLIZZARD WARNING FROM 4 AM TO 7 PM CDT MONDAY FOR MNZ071-072-080-
081.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM CDT MONDAY
FOR MNZ090.
IA...WINTER WEATHER ADVISORY UNTIL 7 PM CDT MONDAY FOR IAZ001-012.
WIND ADVISORY FROM 4 AM TO 7 PM CDT MONDAY FOR IAZ031.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM CDT MONDAY
FOR IAZ002-003-013-014-020>022-032.
NE...WIND ADVISORY FROM 4 AM TO 7 PM CDT MONDAY FOR NEZ013-014.
&&
$$
UPDATE...JH
SHORT TERM...CHAPMAN
LONG TERM...JM
AVIATION...GILLISPIE
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1103 PM EDT SUN MAR 17 2013
.SYNOPSIS...
COLD AIR DAMMING WAS IN CONTROL OF THE AREA WITH A STATIONARY
FRONT TO THE SOUTH...AND WILL REMAIN IN PLACE THROUGH MOST OF THE
DAY MONDAY...UNTIL A COLD FRONT APPROACHES FROM THE WEST LATE IN
THE DAY. THE FRONT WILL TRY TO PUSH BACK EAST...BUT THE WARM AIR
WILL LIKELY ONLY WORK ITS WAY BACK INTO FAR SOUTHWEST VIRGINIA AND
PARTS OF SOUTHEAST WEST VIRGINIA BY LATE MONDAY. WINDY CONDITIONS
SPREAD INTO THE REGION BEHIND THE COLD FRONT TUESDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 1050 PM EDT SUNDAY...
TRANSITION ZONE BETWEEN RAIN AND SNOW COVERS WAS ACROSS VIRGINIA
THIS EVENING AS SHOWN BY THE 00Z SOUNDINGS. RNK HAD A WARM NOSE OF
+4 DEG C AROUND 800 MB WITH A LAYER NEARLY 5000 FEET DEEP ABOVE
FREEZING AND JUST A SMALL LAYER BELOW ZERO. IAD`S SOUNDING WAS
ALL BELOW FREEZING FROM JUST ABOVE THE SURFACE. RAP FORECAST
TEMPERATURE PROFILES WERE CLOSEST TO WHAT WAS OBSERVED AT
00Z...ALONG SURFACE TEMPERATURES THAT WERE MORE REASONABLE IN THE
WEDGE. USING THE COOLER SURFACE TEMPERATURES AND WARMER
TEMPERATURES ALOFT...ADDED MORE POCKETS OF FREEZING RAIN IN ALONG
THE BLUE RIDGE AND IN GREENBRIER COUNTY. EVEN WITH THE CHANGES IN
PRECIPITATION TYPE...LITTLE ADJUSTMENT WAS NEEDED TO OVERALL SNOW
AND SLEET ACCUMULATION. NO CHANGES FOR THE WINTER WEATHER ADVISORY
AT THIS TIME. MOST OF THE QPF COMES IN BEFORE 06Z/2AM.
AS OF 410 PM EDT SUNDAY...
WENT COLDER THAN GUIDANCE FOR HIGHS ON MONDAY...WHICH WILL HAPPEN
VERY LATE IN THE DAY MOST PLACES. WITH WEDGE LIKELY ONLY BREAKING
IN FAR SW AND WESTERN RIDGES...AND POSSIBLE ALSO IN NC PIEDMONT
AND PARTS OF SOUTHSIDE VA...MANY LOCATIONS WILL SEE NEARLY STEADY
TEMPS MONDAY. SHOWERS WILL BE MOVING IN FROM THE WEST LATE IN THE
DAY...WHICH WILL PROVIDE MIXING TO HELP BREAK BREAK THE
WEDGE...AND DECIDED THAT TIMING OF ANY CONVECTIVE POTENTIAL LOOKS
LATE ENOUGH TO NOT MENTION UNTIL EVENING TIME FRAME. THE TRICKY
PART OF MONDAY`S FORECAST IS PERHAPS FASTER TIMING OF ARRIVAL OF
SHOWERS IN THE WEST...AND FASTER BREAKING WEDGE FOR PERHAPS MUCH
WARMER TEMPERATURES AROUND THE SOUTHERN PERIPHERY.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 400 PM EDT SUNDAY...
SURFACE FRONT PROGGED TO BE ON OUR DOORSTEP 8PM MONDAY. THIS FRONT
WILL SWEEP ACROSS THE AREA FROM WEST TO EAST DURING THE OVERNIGHT.
ANTICIPATING NEAR CATEGORICAL THREAT FOR RAIN JUST PRIOR TOO THE
FRONTAL PASSAGE WITH RAPID DECREASE IN PRECIP THREAT AFTER FROPA.
MODELS SUGGEST A QUARTER TO ABOUT A HALF INCH OF RAIN TO BE
ASSOCIATED WITH THE FRONTAL PASSAGE...TEMPERATURES WARM ENOUGH
THAT IT SHOULD BE ALL LIQUID...EXCEPT FOR SOME OF THE HIGHEST
ELEVATIONS WHERE PRECIP MAY CHANGE OVER TO BRIEF PERIOD OF SNOW B4
ENDING.
BY DAYBREAK TUESDAY...FRONT WILL BE EAST OF THE FORECAST AREA WITH
DOWNSLOPE WESTERLIES RESULTING IN CLEARING SKIES ALONG AND EAST OF
THE BLUE RIDGE. LINGERING LOW LEVEL MOISTURE IN THE MTNS MAY
RESULT IN A FLURRY OR TWO THERE.
THE UPPER AIR PATTERN DOES NOT CHANGE MUCH THROUGH MID WEEK WITH
RIDGE IN THE WESTERN CONUS AND TROF IN THE EAST. THIS SUPPORTS
COLDER THAN NORMAL TEMPERATURES ACROSS OUR AREA. NORTHWEST FLOW
TUESDAY WILL PERSIST RIGHT ON INTO WEDNESDAY WITH 85H TEMPS BLOW
FREEZING. FOR THE MOST PART...THE FLOW IS DRY. THERE IS AN UPPER
LEVEL DISTURBANCE WHICH IS PROGGED TO COME THROUGH DURING THE DAY
WEDNESDAY. THIS FEATURE MAY BRING SNOW SHOWERS AND FLURRIES...BUT
MORE IMPORTANTLY A REINFORCING SHOT OF COLD AIR THAT WILL SEND
TEMPERATURES WELL BELOW NORMAL WEDNESDAY NIGHT INTO THURSDAY AS
85H TEMPERATURES TEST M14 DEG C.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 400 PM EDT SUNDAY...
A BLOCKY HEMISPHERIC CIRCULATION IS ADVERTISED BY THE LONG RANGE
MODELS THROUGH NEXT WEEKEND...MARKED BY THREE STRONG POSITIVE HEIGHT
ANOMALIES. THE FIRST IS THROUGH THE BERING SEA WHILE THE SECOND AND
THIRD MERGE BETWEEN THE NORTH POLE AND THE DAVIS STRAIT.
TELECONNECTIONS FROM EACH AREA SUPPORT RIDGING JUST OFF THE WEST
COAST WITH BROAD TROUGHING FROM THE CENTRAL CONUS EASTWARD. THIS
VERY NEGATIVE AO PATTERN SUPPORTS BELOW NORMAL TEMPERATURES EAST OF
THE ROCKIES WITH THE POLAR FRONT ALONG THE GULF COAST.
WEATHER CHALLENGE DURING THIS TIME FRAME IS WHETHER ANY SORT OF
CYCLOGENESIS CAN TAKE PLACE ALONG THIS POLAR FRONT WHICH WILL BE
SITUATED SOUTH OF OUR FCST AREA...AND IF SO CAN ANY OF THIS ENERGY
GAIN ANY LATITUDE PER STRONG WESTERLIES WITHIN THE COLD TROUGH WHICH
WILL BE DIRECTLY OVERHEAD DURING THE PERIOD. FORECAST
SPREAD/UNCERTAINTY AND RUN-RUN CONTINUITY INCREASES SIGNIFICANTLY
HEADING INTO NEXT WEEKEND. RECENT ECMWF/ECMWF ENSEMBLES IN
PARTICULAR HAVE OFFERED MORE SUPPRESSED SOLUTIONS THAN RECENT
GFS/GEFS. THE GFS RUNS INSTEAD OFFER A DEEPER SERN US/MID-ATLC
COASTAL STORM. ENSEMBLES ARE MIXED/IN THE MIDDLE BUT OVERALL FAVOR
A SOLUTION WITH EMPHASIS OVER THE SRN/SERN US...THAT SOME SORT OF
SYSTEM WILL GET GENERATED. SINCE THERE IS NO SOLID CONSENSUS ON
HOW FAR NORTH THIS SYSTEM WILL TRACK...WILL ADVERTISE CHC POPS FOR
THE ENTIRE CWA...WITH FOCUS ON THE SUNDAY TIME FRAME...DAY 7. AS
LUCK WOULD HAVE IT...WINTER ISN`T OVER...SO PTYPE CHALLENGE WILL
ALSO COME INTO PLAY IF THE SYSTEM SPREADS ANY MOISTURE THIS FAR
NORTH.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
AS OF 800 PM EDT SUNDAY...
VERY POOR AVIATION CONDITIONS ARE EXPECTED TONIGHT AND TOMORROW AS A
FRONTAL BOUNDARY STALLS TO THE SOUTH OF THE CWA AND COLD CANADIAN
HIGH PRESSURE MOVES TOWARD THE NORTHERN MID-ATLANTIC. MVFR TO IFR
CIGS AND VSBYS WILL ONLY INTENSIFY AS RAIN SERVES TO INTENSIFY THE
WEDGE. 00Z SOUNDING SUGGESTS A COLD RAIN/DRIZZLE FOR MOST LOCATIONS
TONIGHT AS THERE IS A PRONOUNCED WARM NOSE ALOFT. THE EXCEPTION WILL
BE LWB WHERE SNOW/SLEET IS STILL EXPECTED. THE WEDGE IS EXPECTED TO
LAST THROUGH MONDAY BEFORE THE FRONTAL BOUNDARY FINALLY KICKS IT OUT
AND BEGINS TO IMPROVE CONDITIONS.
TUESDAY THROUGH FRIDAY WILL BE MUCH IMPROVED ACROSS THE REGION. SOME
UPSLOPE SNOW SHOWERS ARE POSSIBLE AT BLF WEDNESDAY AFTERNOON AND
EVENING. THE WINDS WILL PICK UP DRAMATICALLY ON TUESDAY AND
WEDNESDAY ACROSS THE WEST...EXPECT 25-30KT GUSTS AT TIMES FOR
BLF/BCB/LWB/ROA. DESPITE THE WINDS VFR CONDITIONS ARE EXPECTED FOR
THE VAST MAJORITY OF THE REMAINING TAF PERIOD.&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR VAZ018>020-023-024-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR WVZ045.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY UNTIL 2 PM EDT MONDAY FOR VAZ018>020-
023-024-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY UNTIL 2 PM EDT MONDAY FOR WVZ045.
&&
$$
SYNOPSIS...SK
NEAR TERM...AMS/SK
SHORT TERM...PM
LONG TERM...PM
AVIATION...CF
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
833 PM EDT SUN MAR 17 2013
.SYNOPSIS...
COLD AIR DAMMING IS IN CONTROL OF THE AREA WITH A STATIONARY
FRONT TO THE SOUTH...AND WILL REMAIN IN PLACE THROUGH MOST OF THE
DAY MONDAY...UNTIL A COLD FRONT APPROACHES FROM THE WEST LATE IN
THE DAY. THE FRONT WILL TRY TO PUSH BACK NORTH AS A WARM FRONT
LATE IN THE DAY BUT THE WARM AIR WILL LIKELY ONLY WORK ITS WAY
BACK INTO FAR SOUTHWEST VIRGINIA AND PARTS OF THE PIEDMONT BY LATE
MONDAY. WIDESPREAD BUT GENERALLY LIGHT PRECIPITATION... SOME IN
THE FORM OF WINTRY WEATHER ACROSS THE NORTH...WILL OVERSPREAD THE
AREA TONIGHT. THEN WINDY CONDITIONS SPREAD INTO THE REGION BEHIND
THE COLD FRONT BY TUESDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 555 PM EDT SUNDAY...
HAVE ADDED AREAS OF FOG IN THE COLD AIR DAMMING REGION WHERE
VISIBILITIES IN SOME SPOTS WERE BELOW ONE MILE.
AS OF 410 PM EDT SUNDAY...
COLD WEDGE REMAINS IN PLACE ACROSS THE REGION...WITH PATCHES OF
DRIZZLE AND SOME MAINLY LIGHT FOG EXCEPT FOR RIDGES. TEMPERATURES
AND DEW PTS SO FAR REMAIN ABOVE FREEZING AT REPORTING STATIONS IN
THE AREA ALTHOUGH TEMPS HAVE REMAINED STEADY OR SLOWLY FALLING
THIS AFTERNOON WITH MUCH COLDER AIR NOT TOO FAR OFF TO THE NORTH.
MODELS STRUGGLING WITH QPF ALONG 850 FRONT TO OUR NORTHWEST AND
HAVE BEEN TRYING TO PUSH PRECIP IN ACROSS SE WV MOST OF THE DAY.
APPEARS LOOKING AT RADAR AND SOME HELP FROM HRRR THAT THOSE AREAS
WILL HAVE TO WAIT UNTIL AFTER 00Z BEFORE IT BEGINS TO SNEAK INTO
WRN GREENBRIER AGAIN. ALSO MODELS LIKELY OVERDOING SOME UPSLOPE
PRECIP ALONG BLUE RIDGE THIS EVENING...WHICH WILL BE MORE IN THE
FORM OF DRIZZLE...BUT COULD AMOUNT TO A FEW HUNDREDTHS SO WENT
AHEAD AND INCLUDED HIGH CHC TO LIKELY...INCREASING AS THE EVENING
PROGRESSES.
MAIN QSTN OVERNIGHT IS WHICH LOCATIONS WILL SEE FROZEN
PRECIP...AND WITH BIG DIFFERENCES IN TEMP PROFILES ALOFT...THIS IS
TRICKY. NAM STILL HAS STRONG WARM NOSE AND WITH THE COLDEST SFC
TEMPS SUGGEST MANY LOCATIONS FROM NRV NORTHWARD WOULD SEE FREEZING
RAIN. GFS...RAP...AND MANY SREF MEMBERS HAVE WEAK TO NO WARM
NOSE...AND THIS IS THE IDEA WE ARE STILL LEANING WITH IN THE
FORECAST...WHICH WOULD SUGGEST SLEET OR SNOW...THE FARTHER NORTH
UP TOWARD NORTHERN BORDER WITH WFO STERLING...THE MORE SNOW.
PROBLEM IS THE QPF. MOST OF THIS COMES IN BEFORE 06Z...AND MANY
AREAS WOULD STILL BE SEEING RAIN...EXCEPT FOR HIGHEST ELEVATIONS.
ALSO THINK MODELS ARE A BIT OVERDONE ON QPF. WHAT DOES FALL AFTER
MIDNIGHT WOULD BE THE SLEET AND SNOW MIX...BUT PRECIP AMOUNTS WILL
BE FROM A TENTH TO A QUARTER OF AN INCH BY THEN.
BASED ON THIS...LEANED TOWARD LOWER SLEET/SNOW TOTALS THAN
PREVIOUS FORECAST...BUT THIS STILL GIVES 1 TO 3 INCHES ACROSS FAR
NORTH...MAINLY GREENBRIER TO BATH TO ROCKBRIDGE AND INTO HIGHER
ELEVATIONS ALONG BLUE RIDGE. AN INCH OR SO FROM CRAIG TO ROANOKE
TO AMHERST AND PARTS OF GREENBRIER. ONE THING TO CONSIDER IS THE
POSSIBILITY OF SHALLOW MOISTURE UPSLOPING ALONG BLUE
RIDGE...AND/OR THE WARM NOSE AS FCST BY THE NAM BEING A LITTLE
STRONGER...WHICH MIGHT RESULT IN SOME AREAS OF LIGHT FREEZING RAIN
OR FREEZING DRIZZLE. DID NOT INCLUDE THAT SPECIFICALLY IN
FCST... THIS POSSIBILITY IS ONE REASON WHY DECIDED TO LEAVE THE
ADVISORY GOING AS FAR SOUTH AS CRAIG AND BOTETOURT
COUNTIES...SINCE THE SNOW/SLEET ACCUMS WILL BE MINIMAL. ROADS MAY
NOT HAVE MANY PROBLEMS EITHER DUE TO RECENT WARM TEMPS...BUT
BRIDGES AND OVERPASSES...AS WELL AS SIDEWALKS MAY GET A LITTLE
SLICK WITH LIGHT SLEET/SNOW MIX.
WENT WITH COLDER GUIDANCE IN MET FOR LOWS TONIGHT...ACTUALLY 1-2
DEG COLDER IN UPSLOPE AREAS FROM EASTERLY FLOW...AND COLDER THAN
GUIDANCE FOR HIGHS ON MONDAY...WHICH WILL HAPPEN VERY LATE IN THE
DAY MOST PLACES. WITH WEDGE LIKELY ONLY BREAKING IN FAR SW AND
WESTERN RIDGES...AND POSSIBLE ALSO IN NC PIEDMONT AND PARTS OF
SOUTHSIDE VA...MANY LOCATIONS WILL SEE NEARLY STEADY TEMPS MONDAY.
SHOWERS WILL BE MOVING IN FROM THE WEST LATE IN THE DAY...WHICH
WILL PROVIDE MIXING TO HELP BREAK BREAK THE WEDGE...AND DECIDED
THAT TIMING OF ANY CONVECTIVE POTENTIAL LOOKS LATE ENOUGH TO NOT
MENTION UNTIL EVENING TIME FRAME. THE TRICKY PART OF MONDAY`S
FORECAST IS PERHAPS FASTER TIMING OF ARRIVAL OF SHOWERS IN THE
WEST...AND FASTER BREAKING WEDGE FOR PERHAPS MUCH WARMER
TEMPERATURES AROUND THE SOUTHERN PERIPHERY.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 400 PM EDT SUNDAY...
SURFACE FRONT PROGGED TO BE ON OUR DOORSTEP 8PM MONDAY. THIS FRONT
WILL SWEEP ACROSS THE AREA FROM WEST TO EAST DURING THE OVERNIGHT.
ANTICIPATING NEAR CATEGORICAL THREAT FOR RAIN JUST PRIOR TOO THE
FRONTAL PASSAGE WITH RAPID DECREASE IN PRECIP THREAT AFTER FROPA.
MODELS SUGGEST A QUARTER TO ABOUT A HALF INCH OF RAIN TO BE
ASSOCIATED WITH THE FRONTAL PASSAGE...TEMPERATURES WARM ENOUGH
THAT IT SHOULD BE ALL LIQUID...EXCEPT FOR SOME OF THE HIGHEST
ELEVATIONS WHERE PRECIP MAY CHANGE OVER TO BRIEF PERIOD OF SNOW B4
ENDING.
BY DAYBREAK TUESDAY...FRONT WILL BE EAST OF THE FORECAST AREA WITH
DOWNSLOPE WESTERLIES RESULTING IN CLEARING SKIES ALONG AND EAST OF
THE BLUE RIDGE. LINGERING LOW LEVEL MOISTURE IN THE MTNS MAY
RESULT IN A FLURRY OR TWO THERE.
THE UPPER AIR PATTERN DOES NOT CHANGE MUCH THROUGH MID WEEK WITH
RIDGE IN THE WESTERN CONUS AND TROF IN THE EAST. THIS SUPPORTS
COLDER THAN NORMAL TEMPERATURES ACROSS OUR AREA. NORTHWEST FLOW
TUESDAY WILL PERSIST RIGHT ON INTO WEDNESDAY WITH 85H TEMPS BLOW
FREEZING. FOR THE MOST PART...THE FLOW IS DRY. THERE IS AN UPPER
LEVEL DISTURBANCE WHICH IS PROGGED TO COME THROUGH DURING THE DAY
WEDNESDAY. THIS FEATURE MAY BRING SNOW SHOWERS AND FLURRIES...BUT
MORE IMPORTANTLY A REINFORCING SHOT OF COLD AIR THAT WILL SEND
TEMPERATURES WELL BELOW NORMAL WEDNESDAY NIGHT INTO THURSDAY AS
85H TEMPERATURES TEST M14 DEG C.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 400 PM EDT SUNDAY...
A BLOCKY HEMISPHERIC CIRCULATION IS ADVERTISED BY THE LONG RANGE
MODELS THROUGH NEXT WEEKEND...MARKED BY THREE STRONG POSITIVE HEIGHT
ANOMALIES. THE FIRST IS THROUGH THE BERING SEA WHILE THE SECOND AND
THIRD MERGE BETWEEN THE NORTH POLE AND THE DAVIS STRAIT.
TELECONNECTIONS FROM EACH AREA SUPPORT RIDGING JUST OFF THE WEST
COAST WITH BROAD TROUGHING FROM THE CENTRAL CONUS EASTWARD. THIS
VERY NEGATIVE AO PATTERN SUPPORTS BELOW NORMAL TEMPERATURES EAST OF
THE ROCKIES WITH THE POLAR FRONT ALONG THE GULF COAST.
WEATHER CHALLENGE DURING THIS TIME FRAME IS WHETHER ANY SORT OF
CYCLOGENESIS CAN TAKE PLACE ALONG THIS POLAR FRONT WHICH WILL BE
SITUATED SOUTH OF OUR FCST AREA...AND IF SO CAN ANY OF THIS ENERGY
GAIN ANY LATITUDE PER STRONG WESTERLIES WITHIN THE COLD TROUGH WHICH
WILL BE DIRECTLY OVERHEAD DURING THE PERIOD. FORECAST
SPREAD/UNCERTAINTY AND RUN-RUN CONTINUITY INCREASES SIGNIFICANTLY
HEADING INTO NEXT WEEKEND. RECENT ECMWF/ECMWF ENSEMBLES IN
PARTICULAR HAVE OFFERED MORE SUPPRESSED SOLUTIONS THAN RECENT
GFS/GEFS. THE GFS RUNS INSTEAD OFFER A DEEPER SERN US/MID-ATLC
COASTAL STORM. ENSEMBLES ARE MIXED/IN THE MIDDLE BUT OVERALL FAVOR
A SOLUTION WITH EMPHASIS OVER THE SRN/SERN US...THAT SOME SORT OF
SYSTEM WILL GET GENERATED. SINCE THERE IS NO SOLID CONSENSUS ON
HOW FAR NORTH THIS SYSTEM WILL TRACK...WILL ADVERTISE CHC POPS FOR
THE ENTIRE CWA...WITH FOCUS ON THE SUNDAY TIME FRAME...DAY 7. AS
LUCK WOULD HAVE IT...WINTER ISN`T OVER...SO PTYPE CHALLENGE WILL
ALSO COME INTO PLAY IF THE SYSTEM SPREADS ANY MOISTURE THIS FAR
NORTH.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
AS OF 800 PM EDT SUNDAY...
VERY POOR AVIATION CONDITIONS ARE EXPECTED TONIGHT AND TOMORROW AS A
FRONTAL BOUNDARY STALLS TO THE SOUTH OF THE CWA AND COLD CANADIAN
HIGH PRESSURE MOVES TOWARD THE NORTHERN MID-ATLANTIC. MVFR TO IFR
CIGS AND VSBYS WILL ONLY INTENSIFY AS RAIN SERVES TO INTENSIFY THE
WEDGE. 00Z SOUNDING SUGGESTS A COLD RAIN/DRIZZLE FOR MOST LOCATIONS
TONIGHT AS THERE IS A PRONOUNCED WARM NOSE ALOFT. THE EXCEPTION WILL
BE LWB WHERE SNOW/SLEET IS STILL EXPECTED. THE WEDGE IS EXPECTED TO
LAST THROUGH MONDAY BEFORE THE FRONTAL BOUNDARY FINALLY KICKS IT OUT
AND BEGINS TO IMPROVE CONDITIONS.
TUESDAY THROUGH FRIDAY WILL BE MUCH IMPROVED ACROSS THE REGION. SOME
UPSLOPE SNOW SHOWERS ARE POSSIBLE AT BLF WEDNESDAY AFTERNOON AND
EVENING. THE WINDS WILL PICK UP DRAMATICALLY ON TUESDAY AND
WEDNESDAY ACROSS THE WEST...EXPECT 25-30KT GUSTS AT TIMES FOR
BLF/BCB/LWB/ROA. DESPITE THE WINDS VFR CONDITIONS ARE EXPECTED FOR
THE VAST MAJORITY OF THE REMAINING TAF PERIOD.&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR VAZ018>020-023-024-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR WVZ045.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR VAZ018>020-023-024-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR WVZ045.
&&
$$
SYNOPSIS...SK
NEAR TERM...AMS/SK
SHORT TERM...PM
LONG TERM...PM
AVIATION...CF
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
832 PM EDT SUN MAR 17 2013
.SYNOPSIS...
COLD AIR DAMMING IS IN CONTROL OF THE AREA WITH A STATIONARY
FRONT TO THE SOUTH...AND WILL REMAIN IN PLACE THROUGH MOST OF THE
DAY MONDAY...UNTIL A COLD FRONT APPROACHES FROM THE WEST LATE IN
THE DAY. THE FRONT WILL TRY TO PUSH BACK NORTH AS A WARM FRONT
LATE IN THE DAY BUT THE WARM AIR WILL LIKELY ONLY WORK ITS WAY
BACK INTO FAR SOUTHWEST VIRGINIA AND PARTS OF THE PIEDMONT BY LATE
MONDAY. WIDESPREAD BUT GENERALLY LIGHT PRECIPITATION... SOME IN
THE FORM OF WINTRY WEATHER ACROSS THE NORTH...WILL OVERSPREAD THE
AREA TONIGHT. THEN WINDY CONDITIONS SPREAD INTO THE REGION BEHIND
THE COLD FRONT BY TUESDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 555 PM EDT SUNDAY...
HAVE ADDED AREAS OF FOG IN THE COLD AIR DAMMING REGION WHERE
VISIBILITIES IN SOME SPOTS WERE BELOW ONE MILE.
AS OF 410 PM EDT SUNDAY...
COLD WEDGE REMAINS IN PLACE ACROSS THE REGION...WITH PATCHES OF
DRIZZLE AND SOME MAINLY LIGHT FOG EXCEPT FOR RIDGES. TEMPERATURES
AND DEW PTS SO FAR REMAIN ABOVE FREEZING AT REPORTING STATIONS IN
THE AREA ALTHOUGH TEMPS HAVE REMAINED STEADY OR SLOWLY FALLING
THIS AFTERNOON WITH MUCH COLDER AIR NOT TOO FAR OFF TO THE NORTH.
MODELS STRUGGLING WITH QPF ALONG 850 FRONT TO OUR NORTHWEST AND
HAVE BEEN TRYING TO PUSH PRECIP IN ACROSS SE WV MOST OF THE DAY.
APPEARS LOOKING AT RADAR AND SOME HELP FROM HRRR THAT THOSE AREAS
WILL HAVE TO WAIT UNTIL AFTER 00Z BEFORE IT BEGINS TO SNEAK INTO
WRN GREENBRIER AGAIN. ALSO MODELS LIKELY OVERDOING SOME UPSLOPE
PRECIP ALONG BLUE RIDGE THIS EVENING...WHICH WILL BE MORE IN THE
FORM OF DRIZZLE...BUT COULD AMOUNT TO A FEW HUNDREDTHS SO WENT
AHEAD AND INCLUDED HIGH CHC TO LIKELY...INCREASING AS THE EVENING
PROGRESSES.
MAIN QSTN OVERNIGHT IS WHICH LOCATIONS WILL SEE FROZEN
PRECIP...AND WITH BIG DIFFERENCES IN TEMP PROFILES ALOFT...THIS IS
TRICKY. NAM STILL HAS STRONG WARM NOSE AND WITH THE COLDEST SFC
TEMPS SUGGEST MANY LOCATIONS FROM NRV NORTHWARD WOULD SEE FREEZING
RAIN. GFS...RAP...AND MANY SREF MEMBERS HAVE WEAK TO NO WARM
NOSE...AND THIS IS THE IDEA WE ARE STILL LEANING WITH IN THE
FORECAST...WHICH WOULD SUGGEST SLEET OR SNOW...THE FARTHER NORTH
UP TOWARD NORTHERN BORDER WITH WFO STERLING...THE MORE SNOW.
PROBLEM IS THE QPF. MOST OF THIS COMES IN BEFORE 06Z...AND MANY
AREAS WOULD STILL BE SEEING RAIN...EXCEPT FOR HIGHEST ELEVATIONS.
ALSO THINK MODELS ARE A BIT OVERDONE ON QPF. WHAT DOES FALL AFTER
MIDNIGHT WOULD BE THE SLEET AND SNOW MIX...BUT PRECIP AMOUNTS WILL
BE FROM A TENTH TO A QUARTER OF AN INCH BY THEN.
BASED ON THIS...LEANED TOWARD LOWER SLEET/SNOW TOTALS THAN
PREVIOUS FORECAST...BUT THIS STILL GIVES 1 TO 3 INCHES ACROSS FAR
NORTH...MAINLY GREENBRIER TO BATH TO ROCKBRIDGE AND INTO HIGHER
ELEVATIONS ALONG BLUE RIDGE. AN INCH OR SO FROM CRAIG TO ROANOKE
TO AMHERST AND PARTS OF GREENBRIER. ONE THING TO CONSIDER IS THE
POSSIBILITY OF SHALLOW MOISTURE UPSLOPING ALONG BLUE
RIDGE...AND/OR THE WARM NOSE AS FCST BY THE NAM BEING A LITTLE
STRONGER...WHICH MIGHT RESULT IN SOME AREAS OF LIGHT FREEZING RAIN
OR FREEZING DRIZZLE. DID NOT INCLUDE THAT SPECIFICALLY IN
FCST... THIS POSSIBILITY IS ONE REASON WHY DECIDED TO LEAVE THE
ADVISORY GOING AS FAR SOUTH AS CRAIG AND BOTETOURT
COUNTIES...SINCE THE SNOW/SLEET ACCUMS WILL BE MINIMAL. ROADS MAY
NOT HAVE MANY PROBLEMS EITHER DUE TO RECENT WARM TEMPS...BUT
BRIDGES AND OVERPASSES...AS WELL AS SIDEWALKS MAY GET A LITTLE
SLICK WITH LIGHT SLEET/SNOW MIX.
WENT WITH COLDER GUIDANCE IN MET FOR LOWS TONIGHT...ACTUALLY 1-2
DEG COLDER IN UPSLOPE AREAS FROM EASTERLY FLOW...AND COLDER THAN
GUIDANCE FOR HIGHS ON MONDAY...WHICH WILL HAPPEN VERY LATE IN THE
DAY MOST PLACES. WITH WEDGE LIKELY ONLY BREAKING IN FAR SW AND
WESTERN RIDGES...AND POSSIBLE ALSO IN NC PIEDMONT AND PARTS OF
SOUTHSIDE VA...MANY LOCATIONS WILL SEE NEARLY STEADY TEMPS MONDAY.
SHOWERS WILL BE MOVING IN FROM THE WEST LATE IN THE DAY...WHICH
WILL PROVIDE MIXING TO HELP BREAK BREAK THE WEDGE...AND DECIDED
THAT TIMING OF ANY CONVECTIVE POTENTIAL LOOKS LATE ENOUGH TO NOT
MENTION UNTIL EVENING TIME FRAME. THE TRICKY PART OF MONDAY`S
FORECAST IS PERHAPS FASTER TIMING OF ARRIVAL OF SHOWERS IN THE
WEST...AND FASTER BREAKING WEDGE FOR PERHAPS MUCH WARMER
TEMPERATURES AROUND THE SOUTHERN PERIPHERY.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 400 PM EDT SUNDAY...
SURFACE FRONT PROGGED TO BE ON OUR DOORSTEP 8PM MONDAY. THIS FRONT
WILL SWEEP ACROSS THE AREA FROM WEST TO EAST DURING THE OVERNIGHT.
ANTICIPATING NEAR CATEGORICAL THREAT FOR RAIN JUST PRIOR TOO THE
FRONTAL PASSAGE WITH RAPID DECREASE IN PRECIP THREAT AFTER FROPA.
MODELS SUGGEST A QUARTER TO ABOUT A HALF INCH OF RAIN TO BE
ASSOCIATED WITH THE FRONTAL PASSAGE...TEMPERATURES WARM ENOUGH
THAT IT SHOULD BE ALL LIQUID...EXCEPT FOR SOME OF THE HIGHEST
ELEVATIONS WHERE PRECIP MAY CHANGE OVER TO BRIEF PERIOD OF SNOW B4
ENDING.
BY DAYBREAK TUESDAY...FRONT WILL BE EAST OF THE FORECAST AREA WITH
DOWNSLOPE WESTERLIES RESULTING IN CLEARING SKIES ALONG AND EAST OF
THE BLUE RIDGE. LINGERING LOW LEVEL MOISTURE IN THE MTNS MAY
RESULT IN A FLURRY OR TWO THERE.
THE UPPER AIR PATTERN DOES NOT CHANGE MUCH THROUGH MID WEEK WITH
RIDGE IN THE WESTERN CONUS AND TROF IN THE EAST. THIS SUPPORTS
COLDER THAN NORMAL TEMPERATURES ACROSS OUR AREA. NORTHWEST FLOW
TUESDAY WILL PERSIST RIGHT ON INTO WEDNESDAY WITH 85H TEMPS BLOW
FREEZING. FOR THE MOST PART...THE FLOW IS DRY. THERE IS AN UPPER
LEVEL DISTURBANCE WHICH IS PROGGED TO COME THROUGH DURING THE DAY
WEDNESDAY. THIS FEATURE MAY BRING SNOW SHOWERS AND FLURRIES...BUT
MORE IMPORTANTLY A REINFORCING SHOT OF COLD AIR THAT WILL SEND
TEMPERATURES WELL BELOW NORMAL WEDNESDAY NIGHT INTO THURSDAY AS
85H TEMPERATURES TEST M14 DEG C.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 400 PM EDT SUNDAY...
A BLOCKY HEMISPHERIC CIRCULATION IS ADVERTISED BY THE LONG RANGE
MODELS THROUGH NEXT WEEKEND...MARKED BY THREE STRONG POSITIVE HEIGHT
ANOMALIES. THE FIRST IS THROUGH THE BERING SEA WHILE THE SECOND AND
THIRD MERGE BETWEEN THE NORTH POLE AND THE DAVIS STRAIT.
TELECONNECTIONS FROM EACH AREA SUPPORT RIDGING JUST OFF THE WEST
COAST WITH BROAD TROUGHING FROM THE CENTRAL CONUS EASTWARD. THIS
VERY NEGATIVE AO PATTERN SUPPORTS BELOW NORMAL TEMPERATURES EAST OF
THE ROCKIES WITH THE POLAR FRONT ALONG THE GULF COAST.
WEATHER CHALLENGE DURING THIS TIME FRAME IS WHETHER ANY SORT OF
CYCLOGENESIS CAN TAKE PLACE ALONG THIS POLAR FRONT WHICH WILL BE
SITUATED SOUTH OF OUR FCST AREA...AND IF SO CAN ANY OF THIS ENERGY
GAIN ANY LATITUDE PER STRONG WESTERLIES WITHIN THE COLD TROUGH WHICH
WILL BE DIRECTLY OVERHEAD DURING THE PERIOD. FORECAST
SPREAD/UNCERTAINTY AND RUN-RUN CONTINUITY INCREASES SIGNIFICANTLY
HEADING INTO NEXT WEEKEND. RECENT ECMWF/ECMWF ENSEMBLES IN
PARTICULAR HAVE OFFERED MORE SUPPRESSED SOLUTIONS THAN RECENT
GFS/GEFS. THE GFS RUNS INSTEAD OFFER A DEEPER SERN US/MID-ATLC
COASTAL STORM. ENSEMBLES ARE MIXED/IN THE MIDDLE BUT OVERALL FAVOR
A SOLUTION WITH EMPHASIS OVER THE SRN/SERN US...THAT SOME SORT OF
SYSTEM WILL GET GENERATED. SINCE THERE IS NO SOLID CONSENSUS ON
HOW FAR NORTH THIS SYSTEM WILL TRACK...WILL ADVERTISE CHC POPS FOR
THE ENTIRE CWA...WITH FOCUS ON THE SUNDAY TIME FRAME...DAY 7. AS
LUCK WOULD HAVE IT...WINTER ISN`T OVER...SO PTYPE CHALLENGE WILL
ALSO COME INTO PLAY IF THE SYSTEM SPREADS ANY MOISTURE THIS FAR
NORTH.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
AS OF 115 AM EDT
SUNDAY...
VERY POOR AVIATION CONDITIONS ARE EXPECTED TONIGHT AND TOMORROW AS A
FRONTAL BOUNDARY STALLS TO THE SOUTH OF THE CWA AND COLD CANADIAN
HIGH PRESSURE MOVES TOWARD THE NORTHERN MID-ATLANTIC. MVFR TO IFR
CIGS AND VSBYS WILL ONLY INTENSIFY AS RAIN SERVES TO INTENSIFY THE
WEDGE. 00Z SOUNDING SUGGESTS A COLD RAIN/DRIZZLE FOR MOST LOCATIONS
TONIGHT AS THERE IS A PRONOUNCED WARM NOSE ALOFT. THE EXCEPTION WILL
BE LWB WHERE SNOW/SLEET IS STILL EXPECTED. THE WEDGE IS EXPECTED TO
LAST THROUGH MONDAY BEFORE THE FRONTAL BOUNDARY FINALLY KICKS IT OUT
AND BEGINS TO IMPROVE CONDITIONS.
TUESDAY THROUGH FRIDAY WILL BE MUCH IMPROVED ACROSS THE REGION. SOME
UPSLOPE SNOW SHOWERS ARE POSSIBLE AT BLF WEDNESDAY AFTERNOON AND
EVENING. THE WINDS WILL PICK UP DRAMATICALLY ON TUESDAY AND
WEDNESDAY ACROSS THE WEST...EXPECT 25-30KT GUSTS AT TIMES FOR
BLF/BCB/LWB/ROA. DESPITE THE WINDS VFR CONDITIONS ARE EXPECTED FOR
THE VAST MAJORITY OF THE REMAINING TAF PERIOD.&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR VAZ018>020-023-024-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR WVZ045.
&&
$$
SYNOPSIS...SK
NEAR TERM...AMS/SK
SHORT TERM...PM
LONG TERM...PM
AVIATION...CF
AREA FORECAST DISCUSSION
NWS SPOKANE WA
229 PM PDT Sat Mar 16 2013
.SYNOPSIS...
Breezy to windy conditions and colder temperatures will arrive
tonight as the front sweeps through the Inland Northwest. The
mountains will receive several inches of snow tonight into Sunday.
Breezy conditions will persist into Monday and the mountains will
continue to receive rain and snow showers. A break in the active
weather regime is expected on Tuesday before another strong storm
system brings wet and windy weather for Wednesday.
&&
.DISCUSSION...
Tonight and Sunday...
...Mountain snow and increasing winds tonight into Sunday...
A strong cold front passage will occur this evening bringing an
increase in winds...showers...as well as rapidly falling snow
levels with accumulating snow in the Cascades, Blues, and Central
Panhandle Mountains tonight into Sunday morning.
The air mass will continue to destabilize through the early
evening as 500mb temperatures drop to -30 to -33C which combined
with heating from the afternoon will steepen temperature lapse
rates. The GFS and NAM show the best instability generally north
of Interstate 90 with CAPES around 100-200 J/KG where a stray
lightning strike it not out of the question. Strong prefrontal
southwest winds of 20-30 knots at 850mb will result in strong
downslope flow off the Cascades which will limit precipitation
chances with this front for places like Omak, Wenatchee, and Moses
Lake. Behind the front moist...unstable northwest flow will favor
moderate to heavy snow showers in the Cascades impacting travel
along the stretch from Stevens Pass to Coles Corner. A Puget Sound
Convergence Zone is also likely to develop with the HRRR showing a
band of enhanced snow between 7 pm-11 pm in this area...also
impacting Plain and Leavenworth and possibly even as far east as
Wenatchee...with snow levels in the evening falling to near 2000
feet. The strong westerly flow behind the front will shadow out
most of Central and Eastern Washington overnight but snow showers
will redevelop over the Central Panhandle Mountains, Blues, and
possibly the Camas Prairie. This could also make travel difficult
over Lookout Pass overnight and Sunday morning. A cool and
unstable air mass behind the front will promote additional showers
Sunday afternoon...but the high sun angle will make afternoon
accumulations difficult and confined to brief periods under heavy
showers.
With the strong cold front passage 850mb winds will increase to
30-40 knots behind the front overnight. Soundings show a shallow
stable layer which should keep gusts mostly in the 20-30 mph
range. Although local gusts to 40 mph are possible. As mixing
increases on Sunday wind gusts for most valleys will increase to
35-45 mph however pressure gradients will be subsiding which
should keep most locations below advisory level winds. The
northern valleys will be more sheltered from the west winds. JW
Sunday night through Tuesday...The combination of an exiting
upper level trough moving east of the divide and high pressure
building in the eastern Pacific will keep a cool northwest flow
over the Pacific Northwest Sunday night through late Monday. A
series of weak disturbances in the northwest flow will keep some
mention of precipitation across the the eastern zones. The ridge
will track east and through the region Monday night and
Tuesday ahead of the next upstream weather system and result in a
drying trend.
Sunday night and Monday...The upper level flow will become
northwest Sunday night and Monday. The combination of a conditionally
unstable air mass...some weak short wave disturbances and orographic
flow into the Idaho Panhandle favors showers across the eastern
zones. The one ingredient that is lacking is a good moisture
source...which gets cut off from the main flow. In reality this
will just make showers a little more scattered and keep precipitation
amounts on the light side. Snow levels will be such that all
precipitation will be as snow or possibly a rain/snow mix in the
lower mountain valleys. Gusty southwest to west winds will remain
through the evening but are expected to decrease over night. Winds
will increase slightly on Monday but should be 5-10 mph less than
Sunday. Temperatures will remain on the cool side of normal.
Monday night and Tuesday...There are some timing differences in
the models through this period of the forecast and chose to lean
towards a solution that is just slightly faster than the ECMWF.
As the ridge ambles eastward the region will see a drying trend
overnight and early Tuesday. Clearing skies will result in a return
to chilly morning temperatures with lows on the a few degrees
below normal. By Tuesday afternoon the upper flow will back to
south-southwest and allow Pacific moisture to surge back into the
region. The southwest zones will have a chance to get some light
precipitation as warm front approaches. But this will just be the
early stages as the brunt of the moisture is expected Tuesday
night and Wednesday. /Tobin
Tuesday night through Thursday night: A vigorous shortwave trough
of low pressure will swing through the region around mid week.
This shortwave, moving southeast out of the Gulf of Alaska, will
scoop up a closed low pressure system between 140-150W Longitude
and 30-40N Latitude on Monday. The proximity of this closed low to
the sub-tropics will result in flux of very moist air toward the
Inland Northwest. A warm front will push in across the region from
the southwest on Tuesday night. This will result in widespread
stratiform type precip as the region remains in the warm sector of
the weather system through Wednesday. A strong cold front will
move into the Cascades around early Wednesday afternoon and then
spread eastward across the region through the day. Lift along the
cold front will likely enhance precip amounts, but should begin to
dry things out behind the front from west to east. Winds will also
be on the increase with strong cold air advection resulting in a
tightening of surface pressure gradients across the region.
Precipitation...
*Type: Temps at 850 mbs will start at around +3 to +5 Celsius
across southern WA to 0 to -1 Celsius further north along the
Canadian border. These temps will only increase with the warm
front through Tuesday night into Wednesday. This will result in
rising snow levels and valley rain and mountain snowfall. Wet
bulb affects will act to cool the lower portion of the atmosphere
a bit for Tuesday night. So there is still a bit of uncertainty
with snow level at this time, and we may start out as snow or a
rain/snow mix across the northern valleys.
*Amounts: Expect mainly light precip accumulations with the warm
front. Precip intensity will likely increase with the cold front
on Wednesday. Mid level lapse rates will likely become a bit more
unstable as the upper level trough approaches with cold front
passage. As a result, we should see more moderate precip rates
with the cold front. Post frontal showers will continue across the ID
Panhandle Wednesday night into Thursday with snow levels dropping
down to valley floors.
Winds...
We will see some gusty winds possible with the passage of the cold
front on Wednesday and Wednesday night. Best potential for strongest
winds will be in the afternoon and evening hours on Wednesday. We
should remain breezy through Wednesday night before pressure
gradients weaken substantially on Thursday.
Forecast Confidence...
Confidence is moderate at this time. There is relatively good
agreement with the models; however, there are still some subtle
differences. The NAM and SREF is considerably faster than the GFS
and ECMWF, so these solutions were largely ignored with the timing
of this system. /SVH
Friday through Saturday night...A difference in the extended
forecast as models are now less impressed with the upper level
ridge nosing into the Inland Northwest. A Gulf of Alaska low
pressure now looks to keep the ridge suppressed and offshore.
Shortwaves rotating around the low in northwest or west-northwest
flow will keep chances for precipitation going for the Cascades
and the rising terrain of northern Washington and the Idaho
panhandle. The previous forecast had this trend already, and this
was only adjusted slightly. Temperatures look to be right around
seasonal normals for both Friday and Saturday. ty
&&
.AVIATION...
18Z TAFS: Showers will be on the increase today with the best
coverage between 21z-04z. A few of the stronger cells may contain
some small hail or grauple along with brief heavy downpours. Windy
conditions will accompany the passage of the cold front between
21z-01z and post frontal gusts will likely persist through the
night. Gusts of 30kts or more will be possible at Pullman through
the night with gusts of 22-27kt common at KGEG, KSFF, KMWH and
KEAT.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 32 45 28 47 29 49 / 70 30 10 20 10 10
Coeur d`Alene 31 44 27 46 28 48 / 90 40 20 40 30 10
Pullman 30 43 28 46 30 50 / 70 30 20 20 10 20
Lewiston 36 50 33 53 34 57 / 40 30 10 10 10 10
Colville 32 48 29 51 28 55 / 50 30 10 20 10 10
Sandpoint 32 42 29 41 28 45 / 90 50 20 40 40 10
Kellogg 29 39 27 39 27 48 / 100 80 50 50 50 10
Moses Lake 36 52 32 56 31 56 / 20 10 0 0 10 30
Wenatchee 35 51 33 53 33 53 / 20 0 10 10 10 40
Omak 30 50 28 53 27 55 / 10 10 10 10 10 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
920 PM CDT SUN MAR 17 2013
.SHORT TERM...TONIGHT INTO TOMORROW
920 PM CDT SUN MAR 17 2013
NO CHANGES FORTHCOMING WITH THE LOCAL HEADLINES AS CONDITIONS
STILL LOOK LIKE THEY WILL RAPIDLY DETERIORATE OVERNIGHT. THE BAND
OF SNOW THAT WILL MOVE THROUGH THE REGION IS CURRENTLY OVER SIOUX
FALLS SOUTH DAKOTA AND IS PRODUCING A BRIEF PERIOD OF MODERATE TO
HEAVY SNOW WITH VISIBILITY DROPPING TO A HALF MILE OR LESS. 17.23Z
HRRR FORECAST REFLECTIVITY SHOWS THE INITIAL LIGHT SNOW DEVELOPING
ACROSS SOUTHEAST MINNESOTA/NORTHEAST IOWA BETWEEN MIDNIGHT AND 3
AM AND THE HEAVIEST BAND MOVING IN AROUND 4 AM OR LATER. THE MAIN
INITIAL QUESTION IS WITH HOW MUCH SNOW WILL BE ABLE TO DROP OUT OF
THIS BRIEF BAND. DUE TO THE STRONG LOW LEVEL FRONTOGENESIS...EXPECT
THAT THE SNOWFALL RATES WILL BE RATHER INTENSE AT AN INCH OR TWO
INCHES PER HOUR. BUT WITH THE BAND PROGRESSING EASTWARD
QUICKLY...THESE INTENSE SNOWFALL RATES WILL BE BRIEF AND NOT GIVE
A LOT OF TIME FOR THE SNOW TO ACCUMULATE. 17.23Z RAP COBB OUTPUT
STILL PUTS DOWN A SOLID 1 TO 2 INCHES OF SNOW ACROSS THE ADVISORY
AREA WITH HIGH AMOUNTS THE FURTHER NORTH YOU GO. EXPECT TO SEE
SOME HIGHER LOCAL ACCUMULATIONS AS WELL WHERE THE STRONGEST PART OF
THE SNOW BAND ROLLS THROUGH. SO...WILL NOT MAKE ANY CHANGES TO THE
SNOW TOTALS AT THIS POINT.
WILL NOT BE UPGRADING TO A BLIZZARD WARNING FOR THE WIND PRONE
AREAS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA AS THERE REMAINS
SOME UNCERTAINTY WITH THE POTENTIAL FOR A BRIEF PERIOD OF FREEZING
DRIZZLE AFTER THE SNOW FALLS AND BEFORE THE LOW LEVEL COLD FRONT
COMPLETELY MAKES IT THROUGH. 17.23Z RAP BUFKIT SOUNDINGS STILL
SHOW THIS BRIEF PERIOD WHERE THE COLUMN LOSES ICE WITH THE
SATURATED LAYER WARMER THAN -6C AND THERE STILL BEING SOME LOW
LEVEL LIFT THERE. IF THIS FREEZING DRIZZLE DOES OCCUR...IT WILL
HELP TO WEIGH DOWN THE FRESH SNOW AND SUPPRESS IT FROM BLOWING TOO
MUCH. ALSO...SNOW AMOUNTS IN THE 1 TO 2 INCH RANGE WILL LIMIT THE
POTENTIAL FOR BLOWING SNOW/POTENTIAL BLIZZARD CONDITIONS DESPITE
THE WINDS BEING GUSTY IN THE 30-35MPH RANGE.
.LONG TERM...WEDNESDAY THROUGH SUNDAY
235 PM CDT SUN MAR 17 2013
THE MAJORITY OF THE EXTENDED PERIOD LOOKS TO BE RATHER QUIET. HIGH
PRESSURE BUILDS IN BEHIND THE EARLY WEEK STORM SYSTEM AND REMAINS
OVER THE UPPER MIDWEST THROUGH THE END OF THE WORK WEEK. LATEST
12Z MODELS SUGGESTING MAYBE THE POSSIBILITY OF SOME LIGHT
PRECIPITATION FOR NEXT WEEKEND...BUT WITH THE UPCOMING STORM
SYSTEM...HAVE NOT INVESTIGATED THIS AND WILL LET THE MODEL
CONSENSUS GRIDS RIDE.
&&
.AVIATION...TONIGHT AND MONDAY
644 PM CDT SUN MAR 17 2013
CONDITIONS WILL DETERIORATE LATE TONIGHT TOWARD DAYBREAK MONDAY
MORNING AS THE NEXT SYSTEM MOVES INTO THE REGION. EXPECT THAT SNOW
WILL BEGIN TO FALL AT RST AROUND 8-10Z AND LSE AROUND 10-12Z WITH
FLIGHT CONDITIONS DROPPING TO IFR FROM VFR WITHIN 15-30 MINUTES OF
THE SNOW BEGINNING. THE HEAVIEST SNOW BAND WILL MOVE THROUGH
SHORTLY AFTER THE SNOW BEGINS TO FALL AND LIKELY WILL HAVE A BRIEF
PERIOD WHERE VISIBILITY DROPS DOWN TO 1/2SM BEFORE IMPROVING AS
THE BAND PASSES THROUGH. CONDITIONS WILL STAY IFR OR MVFR THROUGH
THE REST OF THE DAY AS THE COLD FRONT COMES THROUGH IN THE LATE
MORNING/EARLY AFTERNOON. WINDS WILL QUICKLY PICK UP IN INTENSITY
AND SHOULD CAUSE SOME BLOWING AND DRIFTING OF SNOW THAT WILL
CONTINUE TO REDUCE VISIBILITY BELOW 6SM. SUSTAINED WEST WINDS OF
18-22KTS WILL BE ACCOMPANIED BY GUSTS OF UP TO 30-35KTS INTO THE
EVENING HOURS ON MONDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
235 PM CDT SUN MAR 17 2013
WI...WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO 1 AM CDT TUESDAY FOR
WIZ017-029-032>034-041-042-053.
WINTER WEATHER ADVISORY FROM 7 AM MONDAY TO 1 AM CDT TUESDAY FOR
WIZ043-044.
MN...WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO 1 AM CDT TUESDAY FOR
MNZ079-086>088-094>096.
IA...WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO 1 AM CDT TUESDAY FOR
IAZ008>010-018-019.
&&
$$
SHORT TERM...HALBACH
LONG TERM...04
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
707 PM CDT SUN MAR 17 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...SUNDAY NIGHT AND MONDAY
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
CENTERED ACROSS THE CENTRAL GREAT LAKES EARLY THIS AFTERNOON. LIGHT
EAST FLOW OFF LAKE MICHIGAN IS PUSHING CLOUDS AND FLURRIES INTO THE
SHORELINE AREAS...BUT TOO MUCH DRY AIR IN PLACE TO REACH THE FOX
VALLEY. THE NEXT STORM SYSTEM IS EMERGING INTO THE NORTHERN PLAINS
AND LOOKS FAIRLY IMPRESSIVE ON SATELLITE IMAGERY. AS THIS CYCLONE
MOVES ACROSS THE AREA TOMORROW...SNOW AMOUNTS AND HEADLINES ARE THE
MAIN FORECAST CONCERNS.
TONIGHT...HIGH PRESSURE WILL SLIDE TO NEW ENGLAND AS THE NEXT STORM
SYSTEM MOVES EAST ACROSS THE PLAINS. MID AND HIGH CLOUDS WILL BE ON
THE INCREASE THROUGH THE NIGHT...AS THE LOW LEVEL PRESSURE GRADIENT
TIGHTENS. AS A RESULT OF MORE CLOUDS AND WIND...TEMPS WILL BE
SIGNIFICANTLY WARMER THAN LAST NIGHT AND MAINLY IN THE TEENS. THE
12Z MODEL SUITE SHOWS A SIMILAR TIMING OF THE ARRIVAL OF THE PRECIP
COMPARED TO WHAT THE PREVIOUS SHIFT SHOWED IN THE FORECAST.
THEREFORE...WILL ONLY SHOW SMALL CHANCES SNEAKING INTO CENTRAL
WISCONSIN BETWEEN 09-12Z.
MONDAY...THE STRONG SHORTWAVE WILL SWING AROUND THE NORTHERN
MISSISSIPPI VALLEY AND BECOME NEGATIVELY TILTED AS IT REACHES
CENTRAL WISCONSIN BY 00Z TUESDAY. SURFACE LOW PRESSURE WILL SHIFT
EAST FROM NORTHERN MINNESOTA TO NORTHERN WISCONSIN DURING THIS SAME
TIME. AS THE PREVIOUS SHIFT MENTIONED...THE SHORTWAVE WILL BRING
STRONG DYNAMICS AND MIXING RATIOS OF ABOUT 3 G/KG...WHICH WILL BE
SUFFICIENT TO PRODUCE SNOWFALL RATES OF AROUND A HALF INCH TO UP TO
ONE INCH PER HOUR (FOR BRIEF PERIODS OF TIME). THE BAND OF SNOW
SHOULD BE PROGRESSIVE...HOWEVER...AND LAST FOR AROUND 6 HOURS OR
SO. IN ADDITION...THE DENDRITIC GROWTH ZONE IS PRETTY HIGH AND NOT
THAT THICK....AND SURFACE TEMPS WILL BE APPROACHING 32 DEGREES OVER
NE WISCONSIN. THEREFORE...EXPECT LOWER SNOWFALL RATIOS THAT WHAT
THE MODELS INDICATE (13-15 TO 1) AND MORE LIKE 10-13:1. WITH
WIDESPREAD QPF AROUND 0.25-0.35...THIS WOULD PUT SNOWFALL AMOUNTS
AROUND 2-4 INCHES FOR MOST LOCATIONS (HIGHER OVER CENTRAL
WISCONSIN). BECAUSE OF FAIRLY BEEFY SNOWFALL RATES DESPITE SOME
AREAS BEING MARGINAL FOR ADVISORY CRITERIA SNOW...WILL ISSUE A
WINTER WEATHER ADVISORY FOR AREAS EXCEPT THE SOUTHERN FOX VALLEY AND
CENTRAL LAKE MICHIGAN SHORELINE. WEST WINDS KICK UP LATE MONDAY
AFTERNOON AND INTO MONDAY EVENING...SO WILL EXTEND THE ADVISORY
THROUGH MID EVENING OR SO TO COVER BLOWING AND DRIFTING CONCERNS.
.LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY
PERIOD WILL BE DOMINATED BY BROAD TROF OVER THE CENTRAL US...WITH
WESTERLIES LYING OVER SOUTHERN HALF OF THE U.S. LOOK FOR PROGRESSIVE
PACIFIC SYSTEMS DIVING THRU THE PLAINS INTO SOUTHEAST U.S...LEAVING
NE WI DRY FOR THE MOST PART...WITH TEMPERATURES RUNNING WELL BELOW
NORMAL.
INITIALLY...UPPER LOW TO MOVE ACROSS THE NORTHERN GREAT LAKES MON
NIGHT. WRAP-AROUND MOISTURE AND CYCLONIC FLOW EXPECTED TO BRING
LIGHT SNOW ACROSS NE WI THRU AT LEAST THE FIRST HALF OF MONDAY NIGHT.
STRONG CAA AND GUSTY WEST WINDS EXPECTED MON NIGHT INTO TUE.
THOUGH WITH CLOUDS AND WINDS...BUMPED MIN TEMPS UP SLIGHTLY FROM
EARLIER SHIFT.
QUESTION THROUGH THE TUE THROUGH WED PERIOD...IS WAVES ROTATING
AROUND THE UPPER LOW AND CHANCE FOR LIGHT PCPN WITH EACH SYSTEM.
DID NOT MAKE CHANGE TO TUE FLURRY FORECAST...THOUGH POTENTIAL
EXIST FOR LIGHT SNOW ON WED...WITH TROF DROPPING SOUTH THROUGH
STATE.
LAKE EFFECT POSSIBLE TUE INTO THU WITH INCOMING COLD AIR MASS AND
MOISTURE CIRCULATING AROUND LOW...THOUGH WITH A W-NW WIND...THE
BETTER ACCUMULATION VALUES ARE EXPECTED TO STAY NORTH OF THE MI/WI
BORDER WITH A TENTH OR TWO OVER NW VILAS COUNTY POSSIBLE.
SOME WEAKENING OF THE BLOCKY PATTERN AT END OF MODEL RUN...THOUGH
NO GREAT WARM-UP IN SIGHT. SPRING POSTPONED FOR AT LEAST ANOTHER
WEEK. DROPPED MAX/MINS TO BELOW GUIDANCE VALUES AS CLIMO EXERTING
TOO MUCH INFLUENCE.
&&
.AVIATION...VFR CONDITIONS EXPECTED TONIGHT WITH JUST MIDDLE AND
HIGH CLOUDS ARRIVING FROM THE WEST. CIGS AND VSBYS WILL ABRUPTLY
LOWER FROM WEST TO EAST MONDAY AS AN AREA OF SNOW MOVES IN AHEAD
OF A FRONTAL SYSTEM. MODERATE SNOW SHOULD FALL FOR AROUND 3 TO 5
HOURS IN MOST PLACES. THERE MAY BE ENOUGH WIND FOR SOME BLOWING
AND DRIFTING SNOW.
RDM
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 7 AM TO 10 PM CDT MONDAY FOR WIZ005-
010-018-019-030-031-035>037-045.
WINTER WEATHER ADVISORY FROM 10 AM TO 10 PM CDT MONDAY FOR
WIZ011>013-020>022-038-039-073-074.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
236 PM CDT SAT MAR 16 2013
.SHORT TERM...TONIGHT AND SUNDAY.
THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW THIS
MORNINGS LIGHT SNOW DIMINISHING AS IT MOVES SOUTH OVER SOUTHERN
WISCONSIN. AFTER A BRIEF MOMENT OF CLEARING...WEST WINDS HAVE
BROUGHT IN ADDITIONAL CLOUD COVER ACROSS MUCH OF NORTHERN WISCONSIN
AND THE UPPER PENINSULA. LOOKING UPSTREAM...A STRONG SHORTWAVE IS
DIVING TO THE SOUTH ALONG THE MANITOBA/ONTARIO BORDER. SNOW SHOWERS
FROM THIS WAVE ARE MAKING IT TO THE NORTHERN MANITOBA BORDER EARLY
THIS AFTERNOON. SNOW SHOWER POTENTIAL FROM THIS WAVE AND
TEMPERATURES ARE THE MAIN FORECAST CONCERNS.
TONIGHT...A STRONG SHORTWAVE WILL SWING SE ACROSS THE SOUTHERN HALF
OF ONTARIO AND LAKE SUPERIOR THIS EVENING. TAIL END OF VORT WILL
BRUSH NORTH-CENTRAL TO NORTHEAST WISCONSIN WITH A FEW HOURS OF
MODERATE MID-LEVEL FORCING. THOUGH THE SHORT RANGE MODELS SUGGEST
PRECIP WOULD BE POSSIBLE AS FAR SOUTH AS THE U.P. BORDER...AREA OF
FORCING AND PRECIP UPSTREAM SUGGEST PRECIP COULD REACH A LITTLE
FARTHER SOUTH INTO WISCONSIN...SO WILL KEEP A SMALL POP OVER THE NE
1/3RD OF THE AREA...WHICH BACKS OFF CHANCES A WEE BIT FROM THE
PREVIOUS FORECAST. NOT EXPECTING MUST ACCUMS HOWEVER. BEHIND THE
SHORTWAVE...WINDS TURN TO THE NORTHWEST AND WILL ADVECT IN ARCTIC
AIR INTO THE REGION. THIS WOULD BE GOOD FOR LAKE EFFECT CHANCES
EXCEPT THAT VERY DRY AIR WILL ALSO ARRIVE AS WELL. SO WILL KEEP
COVERAGE SCT WITH LITTLE ACCUMS. AS HIGH PRESSURE BUILDS IN
LATE...WINDS WILL FALL OFF AND SKIES WILL CLEAR. THIS WILL PROMOTE
TUMBLING TEMPS. LIKE WHAT THE PREVIOUS SHIFT PUT IN FOR MIN TEMPS
AND HAVE ONLY MADE A FEW MINOR CHANGES.
SUNDAY...SURFACE PRESSURE CENTERED ACROSS THE REGION INITIALLY WILL
MOVE TO THE EASTERN GREAT LAKES BY LATE IN THE AFTERNOON. AS WINDS
TURN TO THE EAST AROUND THE HIGH...SHOULD SEE MID LAKE EFFECT BAND
OR BANDS PUSH ONSHORE DURING THE LATE MORNING HOURS. SOME OF THE
REMNANT CLOUDS MAY SPREAD ACROSS INTO CENTRAL WISCONSIN DURING THE
AFTERNOON. SO IN THE END...WILL SEE A MOSTLY SUNNY TO PARTLY CLOUDY
DAY WITH HIGHS A COUPLE DEGREES COOLER THAN TODAY.
.LONG TERM...MAIN FORECAST CONCERNS WILL BE SNOW AMOUNTS LATE
SUNDAY NIGHT INTO MONDAY NIGHT...LAKE EFFECT POTENTIAL...AND
TEMPS. STILL NO SIGNS OF A SPRING-TIME WARM UP AS PERSISTENT
BLOCKING PATTERN REMAINS SITUATED ACROSS EASTERN CANADA AND THE
WESTERN ATLANTIC.
SUNDAY NIGHT WILL START OFF QUIET AS HIGH PRESSURE PUSHES INTO THE
EASTERN GREAT LAKES. THE DEPARTING HIGH WILL ALLOW A SURFACE LOW
PRESSURE TO ORGANIZE AND MOVE INTO THE WESTERN GREAT LAKES...AS A
POTENT SHORTWAVE AND UPPER TROF ALSO PUSH TOWARD THE AREA. FARTHER
SOUTH...A WEAKER SURFACE LOW AND SHORTWAVE WILL BE PUSHING ACROSS
THE OHIO VALLEY. MODELS ARE NOT IN COMPLETE AGREEMENT ON HOW
THESE TWO WILL PHASE OR NOT PHASE...BUT MODELS HAVE BEEN FAIRLY
CONSISTENT FOR THE PAST COUPLE OF RUNS HOLDING OFF ANY POSSIBLE
PHASING UNTIL IT IS EAST OF WISCONSIN. THE SOUTHERN STREAM
SYSTEM STILL LOOKS TO STAY TOO FAR SOUTH TO BRING ANY PRECIP TO
THE AREA SUNDAY AFTERNOON AND EVENING...SO WILL NEED TO WAIT FOR
THE NORTHERN STREAM SYSTEM FOR ANY ACCUMULATING SNOW. CLOUDS WILL
BE INCREASING THROUGH THE NIGHT AS THE NORTHERN SYSTEM APPROACHES.
TEMPS COULD FALL QUICKLY DURING THE EVENING AS SKIES WILL START
OFF PARTLY CLOUDY OR MOSTLY CLEAR...SO LOOK FOR EVENING LOWS WITH
TEMPS SLOWLY RISING OVERNIGHT AS CLOUDS THICKEN AND SNOW
APPROACHES.
SNOW WILL OVERSPREAD THE AREA FROM WEST TO EAST VERY LATE SUNDAY
NIGHT AND MONDAY MORNING AS THE LOW PRESSURE SYSTEM AND POTENT
SHORTWAVE PUSH INTO THE WESTERN GREAT LAKES. MODELS IN DECENT
AGREEMENT WITH THE TRACK...TAKING THE SURFACE LOW TOWARD WESTERN
LAKE SUPERIOR. GEM SEEMS TO REMAIN AN OUTLIER WITH A MUCH SLOWER
SOLUTION. SOME UNCERTAINTY REMAINS ON HOW MUCH (IF ANY) MOISTURE
FROM THE SOUTHERN STREAM WILL GET PULLED INTO THE NORTHERN
SYSTEM...WHICH WILL FACTOR IN TO THE SNOW TOTALS. THIS LOOKS TO BE
A FAIRLY QUICK HITTING SYSTEM WITH THE BEST SNOWS OCCURRING IN A
12 HOUR WINDOW AS BEST Q-G FORCING...LIFT FROM THE LEFT FRONT QUAD
OF AN UPPER JET...AND SURFACE FRONT CROSS THE AREA. STILL LOOKING
FOR A WIDESPREAD 2-5 INCH SNOW THROUGH 06Z TUESDAY...WITH A FEW
HIGHER TOTALS POSSIBLE...ESPECIALLY OVER CENTRAL AND NORTHERN WI.
WILL CONTINUE TO HOLD OFF ON ANY HEADLINE AS QUESTIONS REMAIN ON
HOW MUCH MOISTURE THERE WILL BE...PLUS THE MAJORITY OF THE SNOW
WILL FALL DURING THE DAY WITH TEMPS IN THE UPPER 20S AND LOWER 30S
AND THE MID MARCH SUN WILL HELP WARM THE GROUND...SO DAYTIME
ACCUMULATIONS ON THE ROADS MAY BE LIMITED...ESPECIALLY OVER THE
EAST.
SNOW WILL DIMINISH QUICKLY AS THE BEST DYNAMICS PUSH NORTH/EAST OF
THE AREA MONDAY NIGHT. CYCLONIC FLOW COULD KEEP SOME LIGHT SNOW OR
FLURRIES ACROSS NORTHERN WI OVERNIGHT...BUT WINDS LOOK TOO
WESTERLY TO GET ANY SUBSTANTIAL LAKE EFFECT ACTIVITY INTO NORTH-
CENTRAL WI. AN ADDITIONAL INCH IS POSSIBLE ACROSS THE NORTH. WEST
WINDS WILL KICK UP BEHIND THE SURFACE FRONT...WHICH WILL PRODUCE
SOME BLOWING AND DRIFTING SNOW. STRONG COLD AIR ADVECTION WILL
BEGIN MONDAY NIGHT AND CONTINUE INTO TUESDAY. MODELS HINT AT
ANOTHER SHORTWAVE ROTATING THROUGH THE AREA ON TUESDAY...WITH
CYCLONIC FLOW IN PLACE ALONG WITH LINGERING MOISTURE. WILL ADD
SOME FLURRY MENTION COVER FOR NOW. GUSTY NE WINDS WILL COMBINE
WITH TEMPS ONLY IN THE 20S TO PRODUCE A BLUSTERY/COOL DAY. WINDS
BEGIN TO TURN MORE TO THE NW TUESDAY AFTERNOON...THEN REMAIN NW
INTO THURSDAY MORNING. DELTA T VALUES WILL HOVER IN THE MID TEENS
TO PRODUCE A LONG DURATION LAKE EFFECT SNOW EVENT. HIGHEST
ACCUMULATIONS WILL REMAIN IN UPPER MICHIGAN...BUT DO EXPECT AT
LEAST SOME ACCUMULATION IN THE FAVORED LAKE EFFECT AREAS OF NORTH-
CENTRAL WI.
CYCLONIC FLOW AROUND THE LOW WHICH BY LATE IN THE WEEK WILL ONLY
MOVE INTO THE EASTERN GREAT LAKES WILL KEEP COOL CONDITIONS ACROSS
THE REGION UNDER PARTLY CLOUDY SKIES. MODELS HAVE THE SYSTEM AT
THE END OF THE WEEK WELL SOUTH OF THE REGION...SO WILL CONTINUE
WITH A DRY FORECAST.
&&
.AVIATION...PLENTY OF MVFR CIGS OVER NORTHERN WISCONSIN TODAY WILL
IMPROVE TO LOW END VFR BY MID TO LATE AFTERNOON. A STRONG UPPER
LEVEL DISTURBANCE WILL MOVE ACROSS THE LAKE SUPERIOR REGION THIS
EVENING. POTENTIAL IS THERE FOR SNOW SHOWERS TO MOVE ACROSS
NORTHERN WISCONSIN AHEAD OF THIS FEATURE. PROBABILITY IS TOO LOW TO
INCLUDE IN THE RHI TAF AT THIS TIME...BUT POTENTIAL FOR A BRIEF
PERIOD OF MVFR OR IFR VSBYS IN LIGHT SNOW IS THERE THIS EVENING.
SKIES TO CLEAR AFTER MIDNIGHT WHEN HIGH PRESSURE BUILDS INTO THE
REGION.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/BERSCH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1128 PM MDT SUN MAR 17 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 258 PM MDT SUN MAR 17 2013
...STRONG WINDS AND HIGH FIRE DANGER THE MAIN CONCERN FOR THE I-25
CORRIDOR AND ADJACENT PLAINS...
UPPER TROF CURRENTLY MOVING ACROSS THE AREA WITH NICE DRYING ON THE
BACK SIDE MOVING ACROSS THE SOUTHEAST MOUNTAINS. SOUTHWEST WINDS
HAVE BEGUN TO INCREASE ALONG THE I-25 CORRIDOR...WITH THE SOUTHERN
I-25 CORRIDOR SEEING THE STRONGEST GUSTS THUS FAR...WITH I-25 AT
BUTTE CREEK PICKING UP A GUST TO AROUND 54 MPH SHORTLY AFTER 18Z.
THIS WAS ABOUT THE TIME A WAVE OF THUNDERSTORMS MOVED OFF THE
MOUNTAINS IN THAT AREA. THESE THUNDERSTORMS HAVE SINCE PUSHED OFF
INTO THE FAR SOUTHEAST PLAINS...AND WEATHER SPOTTERS IN THE AREA
HAVE REPORTED SOME BRIEF PEA SIZE HAIL WITH THE STRONGER CELLS. SO
FAR...WIND GUSTS HAVE STAYED UNDER 50 MPH. THIS MAY BE DUE TO THE
FACT THAT SURFACE DEW POINTS ARE STILL FAIRLY HIGH...EVEN BEHIND THE
SFC TROF AXIS...AND WITH LESS OF A T/TD SPREAD...ACCELERATION FROM
DOWNDRAFTS HASN/T BEEN STRONG ENOUGH TO GOOSE WIND SPEEDS ABOVE HIGH
WIND CRITERIA. WILL CONTINUE TO MONITOR THOUGH AS THESE CELLS
CONTINUE TO PROGRESS EASTWARD THROUGH THE AFTERNOON.
MEANWHILE...SFC DEW POINTS HAVE BEGUN TO DROP OFF INTO THE TEENS
ALONG THE I-25 CORRIDOR...AND TEMPERATURES HAVE WARMED INTO THE
LOWER TO MID 60S ACROSS THE SOUTHERN I-25 CORRIDOR. STILL WAITING
FOR THE HUMIDITIES TO DROP BELOW 15 PERCENT...THOUGH FCS AND RED
CREEK RAWS ARE AT 16% AS OF 2 PM. LOCAL 4KM WRF STILL SHOWS DEW
POINTS DROPPING INTO THE LOWER TEENS ALONG THE I-25 CORRIDOR BY
22Z...AND SPREADING EASTWARD INTO THE FAR EASTERN COUNTIES BY 00Z.
SINCE LINE OF CONVECTION THUS FAR WASN/T ENOUGH TO GOOSE UP WINDS
ABOVE HIGH WIND CRITERIA...ONE WINDOW HAS CLOSED. HOWEVER...ANOTHER
SHOT FOR SOME SPOTTY HIGH WIND CRITERIA OPENS AGAIN AROUND 00Z AS
STRONGER WINDS ALOFT BEHIND THE FRONT SPREAD INTO THE I-25
CORRIDOR. BOTH WRF...AND HRRR SHOW WIND GUSTS UP TO 40-45 KTS.
LOCAL 4KM WRF HAS TRENDED DOWN WITH THESE GUSTS THOUGH AS COMPARED
TO THE EARLIER 00Z RUN. SO ALTHOUGH I CAN/T ENTIRELY RULE OUT A
SPOTTY HIGH WIND CRITERIA GUST ALONG THE I-25 CORRIDOR THROUGH EARLY
EVENING...IF IT DOES OCCUR...THINK IT WILL BE TOO SPOTTY/BRIEF TO WARRANT
ANY HIGH WIND HIGHLIGHTS. NAM12 MODELS HINT AT A WEAK MTN TOP
STABLE LAYER DEVELOPING BY 03Z...BUT 18Z NAM HAS DONE AWAY WITH THIS
FEATURE. BY 06Z...WINDS QUICKLY ATTAIN QUITE A BIT OF FORWARD
SHEAR...WHICH SHOULD CUT OFF ANY MTN WAVE POTENTIAL. BOTTOM
LINE...PARAMETERS APPEAR TO NOT BE IN PLACE LONG ENOUGH TO JUSTIFY A
HIGH WIND WARNING AT THIS POINT. WITHOUT A CRITICAL LAYER IN
PLACE...A WAVE INDUCED ONE WOULD HAVE TO OCCUR TO BRING STRONG WINDS
DOWN...AND THIS SEEMS LESS AND LESS LIKELY...THOUGH NOT ENTIRELY
IMPOSSIBLE.
MEANWHILE...OROGRAPHIC SNOW SHOWERS WILL CONTINUE ALONG THE
CONTINENTAL DIVIDE...THOUGH SHOULD BE DECREASING RAPIDLY IN COVERAGE
OVERNIGHT. ANOTHER 1 TO 2 INCHES WILL BE POSSIBLE OVERNIGHT WITH
SOME POOR VISIBILITIES AT TIMES IN WIND DRIVEN SNOW. HAVE BEEN
MONITORING WEB CAMS...AND SO FAR VISIBILITY HASN/T BEEN IMPACTED
THAT MUCH TO WARRANT AN ADVISORY. IN FACT...CDOT WEB CAMS OVER WOLF
CREEK AND FREMONT PASSES SHOW THE ROADS HAVE MELTED OUT IN THE PAST
COUPLE HOURS. MOST HAZARDOUS CONDITIONS WILL LIKELY CONTINUE ACROSS
MONARCH PASS WHERE ROAD SFC WILL STAY SNOW COVERED.
FOR TOMORROW...WINDS WILL INCREASE AGAIN ALONG THE I-25 CORRIDOR AND
WITH DEEP DRY AIR OVER THE REGION...SFC DEW POINTS WILL FALL INTO
THE SINGLE DIGITS AND EVEN BELOW ZERO. ALTHOUGH WINDS ARE NOT
EXPECTED TO BE A STRONG AS THEY WERE TODAY...WE COULD BE LOOKING AT
BRIEF CRITICAL FIRE WEATHER CONDITIONS ACROSS
PUEBLO...CROWLEY...OTERO...AND PERHAPS PORTIONS OF LAS ANIMAS COUNTIES
IN THE AFTERNOON. FOR NOW...NOT GETTING A LONG ENOUGH DURATION (3
HRS OR MORE) OF HUMIDITY BELOW 15 PERCENT...SO WILL HOLD OFF ON ANY
FIRE WEATHER HIGHLIGHTS. BUT THIS MAY NEED TO BE REVISITED WITH
FUTURE MODEL RUNS. TEMPERATURES SHOULD BE A LITTLE COOLER
TOMORROW...BUT WITH THE WIND THEY SHOULD STILL WARM INTO THE 50S
ACROSS THE PLAINS...WITH 30S AND 40S ACROSS THE HIGH COUNTRY. -KT
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 258 PM MDT SUN MAR 17 2013
...COOLER AND MORE UNSETTLED WEATHER FOR MID WEEK AND BEYOND...
MONDAY NIGHT-TUESDAY NIGHT...MODERATING WESTERLY FLOW PROGGED
ACROSS THE REGION WITH FLAT RIDGING BUILDING ACROSS THE GREAT BASIN
AND INTO THE ROCKIES. WILL CONTINUE TO SEE SOME LIGHT SNOW SHOWERS
ACROSS THE CENTRAL MTS MONDAY EVENING WITH SHOWERS ENDING THROUGH
THE LATE EVENING AND OVERNIGHT HOURS WITH DEVELOPING WAA. WITH THE
DECREASING FLOW ALOFT AND DECOUPLED WINDS ACROSS THE PLAINS...HAVE
LOWERED OVERNIGHT LOWS A TAD...ESPECIALLY ACROSS VALLEY LOCALES.
SOME MODEL DIFFERENCES CONTINUE TO BE INDICATED FOR TUESDAY
AFTERNOON AND EVENING AS THE LATEST ECMWF CONTINUES TO INDICATE
STRONGER SOUTHERN STREAM ENERGY TRANSLATING ACROSS THE DESERT SW
AND NORTHERN NEW MEXICO AND PRINTS OUT SOME LIGHT QFP ACROSS THE
SOUTHERN MTS TUESDAY AFTERNOON AND EVENING. THE GFS IS A LITTLE
FURTHER SOUTH WITH THIS SYSTEM AND ITS ASSOCIATED QPF. AT ANY
RATE...HAVE FOLLOWED CLOSER TO THE GFS SOLUTION WITH LATEST WPC
(FORMERLY HPC) GUIDANCE TRENDING AWAY FROM A DISTINCT SOUTHERN
STREAM SHORTWAVE AT THIS TIME...AND HAVE STARTED TO TRIM BACK THE
SLIGHT POPS ACROSS THE HIGHER TERRAIN OF THE CONTDVD FOR TUESDAY
AFTERNOON AND EVENING. AS FOR TEMPERATURES...WITH WEAK UPSLOPE FLOW
PROGGED ACROSS THE EASTERN PLAINS...HAVE TRIMMED BACK HIGHS A TAD AS
WELL THOUGH SHOULD STILL BE NEAR SEASONAL AVERAGES.
WEDNESDAY-FRIDAY...COOLER AND MORE UNSETTLED WEATHER REMAINS IN THE
OFFING...THOUGH MODELS HAVE TRENDED SLOWER AND FURTHER NORTH WITH
THE BROAD UPPER TROUGH CARVING OUT ACROSS THE WEST COAST ON
WEDNESDAY WHICH THEN CONTINUES TO TRANSLATE OUT ACROSS THE NORTHERN
GREAT BASIN AND THE NORTHERN ROCKIES THROUGH FRIDAY. THIS FURTHER
NORTH TREND WOULD KEEP THE BULK OF THE PRECIPITATION ACROSS THE
CENTRAL MTS THROUGH NORTHEASTERN COLORADO AND NORTHWESTERN KANSAS
WITH MORE DOWNSLOPE FLOW IN PLACE ACROSS SOUTHEAST COLORADO. AT ANY
RATE...MOISTURE INCREASES ACROSS THE CONTDVD WEDNESDAY WITH SHOWERS
DEVELOPING THROUGH MORNING AND INCREASING IN COVERAGE AND SPREADING
EAST THROUGH THE AFTERNOON AND EVENING. SHOWERS TO CONTINUE ACROSS
THE HIGHER TERRAIN WEDNESDAY NIGHT AND THURSDAY AS BROAD TROUGH
CONTINUES TO MOVE EAST...AND MAY NEED SOME HIGHLIGHTS THROUGH THIS
PERIOD...MAINLY FOR THE CENTRAL MTS. BEST CHANCES OF RAIN AND SNOW
SHOWERS ACROSS THE EASTERN COLORADO LOOKS TO BE THURSDAY AFTERNOON
AND NIGHT AS AN ASSOCIATED COLD FRONT BACKS ACROSS THE PLAINS.
SHOWERS TO PERSIST ACROSS MAINLY THE HIGHER TERRAIN ON FRIDAY WITH
COOL NORTHWEST FLOW AND POSSIBLE TRAILING ENERGY TRANSLATING ACROSS
THE GREAT BASIN. HIGHS ON FRIDAY LOOK TO BE WELL BELOW SEASONAL
LEVELS WITH THE COLD AIRMASS IN PLACE.
SATURDAY-SUNDAY...LOW CONFIDENCE FORECAST CONTINUES INTO THE WEEKEND
AS THE LATEST EC CONTINUES TO INDICATE COOL NORTHWEST FLOW WITH
SEVERAL EMBEDDED SHORTWAVES TRANSLATING THROUGH THE FLOW...WHERE AS
THE GFS HAS SHORT WAVE RIDGING BUILDING ACROSS THE GREAT BASIN AND
INTO THE ROCKIES. WITH THAT SAID...HAVE STAYED WITH MODEL CONSENSUS
WHICH KEEPS ISOLATED POPS ACROSS THE HIGHER TERRAIN ALONG WITH A
SLOW WARMUP TO SEASONAL TEMPERATURES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1125 PM MDT SUN MAR 17 2013
EXPECTING VFR CONDITIONS AT KCOS...KPUB AND KALS TONIGHT AND
MONDAY. WESTERLY WINDS WILL INCREASE FOR THE AFTERNOON HOURS AT
THE THREE TAF SITES...WITH GUSTS OF 25 TO 35 KTS LIKELY.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KT
LONG TERM...MW
AVIATION...28
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
421 AM EDT MON MAR 18 2013
...STRONG TO SEVERE STORMS EXPECTED TODAY AND TONIGHT...
.SHORT TERM /TODAY THROUGH TUESDAY/...
PRIMARY CONCERN THROUGH THE SHORT TERM IS CONVECTION EXPECTED TODAY
THROUGH EARLY TUESDAY ACCOMPANYING FRONTAL PASSAGE. MODELS IN FAIRLY
GOOD AGREEMENT WITH INCREASING PRECIP COVERAGE ACROSS THE AREA
THROUGH THIS AFTERNOON...AHEAD OF THE BOUNDARY...THEN PUSHING THE
FRONT THROUGH THE AREA BY TUESDAY MORNING.
HI RES SHORT TERM MODELS SHOWING TWO WAVES OF PRECIP THROUGH TUESDAY
MORNING...AND PRECIP TODAY WILL BE MORE CONVECTIVE IN NATURE THAN
HAD BEEN EXPECTED OVER THE LAST SEVERAL DAYS. HRRR AND LOCAL WRF
BRING PRECIP INTO THE AREA BY LATE MORNING...AND SPREAD IT EASTWARD
THROUGH THE AFTERNOON. THIS ACTIVITY AND ASSOCIATED CLOUD COVER WILL
IMPACT THE DESTABILIZATION OF THE ATMOSPHERE...BUT EVEN SO...MODELS
STILL SUGGEST ML CAPE OF 700 TO 900 J/KG THROUGH THE AFTERNOON
ACROSS NORTH AND CENTRAL GEORGIA...AND 900-1100 J/KG INTO THE
OVERNIGHT HOURS ACROSS PORTIONS OF CENTRAL AND SOUTH GEORGIA. HAVE
CONTINUED WITH ISOLATED THUNDER MENTION THROUGH THE MORNING
HOURS...AND THEN PREDOMINATE THUNDERSTORMS THROUGH THE EVENING.
MODELS CONTINUE TO ADVERTISE WEDGE IN PLACE THROUGH THE DAY...WHICH
WILL SUPPORT A MORE STABILIZED ENVIRONMENT ACROSS NORTHEAST GEORGIA.
THAT BEING SAID...THE PERIPHERY OF THE WEDGE WILL SUPPORT LOCALIZED
ENHANCED SRH AND THE DEVELOPMENT OF STRONG TO SEVERE STORMS. THIS
INCREASED LOW-LEVEL SHEAR COULD SUPPORT ISOLATED TORNADOES. PRIMARY
CONCERNS ACROSS THE AREA WILL BE DAMAGING WINDS AND LARGE
HAIL...ESPECIALLY IN ORGANIZED BANDS OF CONVECTION. ROTATION IS
POSSIBLE WITHIN STRONGER UPDRAFTS IN ORGANIZED STORMS.
SEVERE POTENTIAL DOES DIMINISH SOMEWHAT IN THE OVERNIGHT HOURS...AND
SOME MODELS ARE SUGGESTING A LESS ORGANIZED BAND OF ACTIVITY
ACCOMPANYING THE FRONT THROUGH THE AREA OVERNIGHT INTO TUESDAY
MORNING. WITH SOME UNCERTAINTY ON TIMING AND STRENGTH OF THE
ACTIVITY...HAVE GENERALLY GONE WITH SLIGHTLY LESS THAN CATEGORICAL
POPS AND SCATTERED THUNDERSTORMS FOCUSED ALONG THE BOUNDARY
OVERNIGHT. PRECIP CHANCES SHOULD DROP OFF QUICKLY BEHIND THE
FRONT...SO HAVE LIMITED POPS AND TS MENTION FOLLOWING THE FROPA.
FRONT IS EXPECTED TO PUSH THROUGH THE CWA BY TUESDAY
AFTERNOON...WITH A DRIER AND COOLER AIR MASS IN PLACE AS A RESULT.
THIS AIR MASS WILL REMAIN IN PLACE INTO THE EXTENDED FORECAST
PERIODS.
31
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
EXTENDED PERIOD BEGINS WITH THE DEVELOPMENT OF A LONGWAVE EAST
COAST TROUGH WHICH WILL ALLOW FOR TEMPS DROPPING SOME 10 DEGREES
BELOW NORMAL INITIALLY WITH ADDITIONAL SHOTS OF COOL TO COLD AIR
THROUGH WEEKS END. WILL SEE STRONG IMPULSE PUSH THROUGH THE
TENNESSEE VALLEY EARLY WEDNESDAY WITH MAIN FORCING REMAINING JUST
NORTH OF THE GEORGIA MOUNTAINS. MID LEVEL MOISTURE AND LIFT
SUPPORT SLIGHT CHANCE POPS BUT WITH DEWPOINTS REMAINING IN THE
20S...WILL KEEP POPS IN THE SILENT 10 RANGE FOR NOW. THIS WILL
BEAR WATCHING CLOSELY HOWEVER AS IF PRECIP COULD BE
REALIZED...COLD TEMPS ALOFT AND WET BULB EFFECTS LOOK TO EASILY
SUPPORT WINTRY PRECIP FOR THE NORTHERN TIER.
NEST SYSTEM WILL TAKE SHAPE FRIDAY OVER THE SOUTHERN PLAINS AS
SOUTHERN STREAM OF THE JET GETS ACTIVE AND DEVELOPS LOW PRESSURE
OVER EAST TEXAS. FAVORABLE LARGE SCALE ISENTROPIC ASCENT PROFILE
FOR THE GULF COAST INCLUDING THE LOCAL AREA THROUGH FRIDAY. WILL
HAVE TO MONITOR ONSET CLOSELY FOR THIS SYSTEM AS COLD AIR REMAINS
TRAPPED IN THE MOUNTAINS INITIALLY WHICH COULD LEAD TO ADDITIONAL
WINTRY WX CONCERNS. WARM BELT SHOULD CONTINUE TO LIFT NORTH AS
PRECIP BECOMES MORE ENTRENCHED OVER THE AREA WITH ALL RAIN
EXPECTED FOR THE REMAINDER OF THE TENURE OF THIS STORM SYSTEM.
SIGNIFICANT DIFFERENCES AMONG THE ECMWF AND GFS BY THIS TIME
PERIOD WITH EURO CLEARING IT OUT A BIT FASTER BUT BRINGING IN NEXT
SYSTEM MUCH FURTHER SOUTH THAN GFS. MOST CONFIDENCE IS FOR LATE
FRI AND EARLY SAT AND INCREASED POPS TO HIGH END CHANCE THIS FAR
OUT BUT FORECAST WILL LIKELY REQUIRE SIGNIFICANT TWEAKS WITH
SUBSEQUENT ISSUANCES.
DEESE
&&
.AVIATION...
06Z UPDATE...
MVFR CIGS DEVELOPING ACROSS MUCH OF THE AREA THIS MORNING...WITH
IFR ACROSS PORTIONS OF CENTRAL GA. -SHRA EXPECTED TO MOVE IN MID-
MORNING...WITH TS AND LOW VFR CIGS EXPECTED GENERALLY AFTER 18Z.
EXPECT TWO WAVES OF PRECIP...WITH THE FIRST THIS AFTERNOON WITH A
HIGHER TS POTENTIAL...AND THE SECOND OVERNIGHT WITH THE FRONTAL
PASSAGE...WITH LOWER TS CHANCES. SSE WINDS EXPECTED THROUGH
MORNING...THEN A SWITCH SW AND EVENTUALLY TO THE WEST WITH SPEEDS
OF 8-11KT.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS...EXCEPT HIGH CONFIDENCE ON WINDS.
31
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 65 50 65 37 / 90 90 10 5
ATLANTA 69 49 62 39 / 90 90 10 5
BLAIRSVILLE 59 43 55 32 / 90 90 10 10
CARTERSVILLE 68 48 62 36 / 90 90 10 10
COLUMBUS 72 56 68 42 / 80 60 10 10
GAINESVILLE 62 48 62 37 / 90 90 10 5
MACON 70 55 69 40 / 80 60 20 10
ROME 69 46 62 35 / 90 90 10 10
PEACHTREE CITY 69 51 64 36 / 80 80 10 10
VIDALIA 75 62 71 44 / 60 50 30 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...31
LONG TERM....DEESE
AVIATION...31
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
246 AM EDT MON MAR 18 2013
.PREV DISCUSSION... /ISSUED 1005 PM EDT SUN MAR 17 2013/
UPDATE...
HAVE MADE SEVERAL MINOR TWEAKS TO GRIDS THIS EVENING. UPDATED TEMP
AND DEWPOINT TRENDS OF COURSE. MADE CHANGES TO SKY GRIDS AS WELL
TO INCREASE SKY COVER OVERNIGHT. REDUCED POPS UP NORTH AND
ADJUSTED POPS IN SOUTHERN ZONES TO MATCH MORE OF WHAT THE HRRR AND
OUR LOCAL WRF WERE REFLECTING FOR THE LIGHT RAIN MOVING TOWARD
SOUTH CAROLINA THIS EVENING. FOR TOMORROW...MADE SOME MINOR
ADJUSTMENTS TO HOURLY TEMPS AND DEWPOINTS TO REFLECT THE LOCATION
OF THE WEDGE FRONT IN NORTHEAST GEORGIA. KEPT THUNDER TRENDS
PRETTY MUCH THE SAME BUT DID INCREASE POPS EARLY IN THE DAY TO
ACCOUNT FOR HI-RES MODEL TRENDS...ALL WANTING TO BRING SHOWERS
INTO NORTHWEST GEORGIA AROUND 12Z. SPC SREF DOES BRING SBCAPE
250-500 J/KG BEFORE 18Z SO FEEL THAT KEEPING SLIGHT CHANCE THUNDER
IN THE MORNING IS THE PRUDENT COURSE OF ACTION.
TDP
PREV DISCUSSION... /ISSUED 758 PM EDT SUN MAR 17 2013/
PREV DISCUSSION... /ISSUED 333 PM EDT SUN MAR 17 2013/
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
CURRENT SATELLITE LOOP SHOWS INCREASED MID AND HIGH CLOUDS OVER THE
AREA WITH SHORTWAVE MOVING NE OUT OF THE GULF INTO SOUTH GA. THIS
WAVE MAY BRING SOME SHOWERS TO THE CSG AND MCN AREAS BUT THE
BIGGEST CONCERN IN THE SHORT TERM IS THE FRONTAL PASSAGE EXPECTED
MONDAY AFTERNOON INTO TUESDAY MORNING. THE CLOSED LOW PRESSURE
CENTER OVER MONTANA AND WYOMING WILL MOVE EAST AND DEEPEN OVER THE
NEXT 24-48 HOURS. THIS LOW CENTER BEGINS TO DEVELOP A FAIRLY
ORGANIZED COLD FRONT OVER NIGHT WITH THE TAIL END OF IT SWEEPING
THROUGH NORTH AND CENTRAL GA MONDAY NIGHT INTO TUESDAY MORNING.
EXPECT PRE-FRONTAL ACTIVITY MONDAY INTO MONDAY NIGHT...SO WILL
CONTINUE WITH CHANCE POPS ACROSS A LARGE PORTION OF THE AREA...AND
LIKELY POPS ACROSS NORTHWEST GEORGIA. THESE POPS WILL INCREASE
THROUGH THE DAY AS FRONT APPROACHES...AND CONTINUE TO INCREASE
THROUGH THE OVERNIGHT HOURS AS THE FRONT PUSHES THROUGH THE STATE.
SPC HAS MOST ALL OF NORTH GA AND A GOOD PORTION OF EASTERN GA
OUTLOOKED IN A SLIGHT RISK FOR MONDAY AND MONDAY NIGHT. MODELS
SUGGESTING SBCAPE...MUCAPE AND MLCAPE WILL BE NEAR IN THE 900-1100 J/KG
RANGE BY MONDAY AFTERNOON...AND GIVEN THE ENVIRONMENT...EXPECT
SURFACE BASED STORMS TO REALLY TAP INTO THE UNSTABLE ATMOSPHERE.
THE BEST LAPSE RATES ALSO PEAK AROUND 18Z MON TO 00Z TUE. STRONG
TO SEVERE STORMS CAN BE EXPECTED...AND PRIMARY CONCERN REMAINS TO
BE DAMAGING WINDS...THOUGH SOME ROTATION IS POSSIBLE WITHIN
STRONGER UPDRAFTS. MODELS SUGGESTING WEDGE IN PLACE ACROSS
NORTHEAST GEORGIA...WHICH WILL ACT TO STABILIZE THE WEDGED
AREA...BUT THE BOUNDARY ALONG THE PERIPHERY OF THE WEDGE WILL BE A
CATALYST FOR ENHANCED STORMS TO DEVELOP.
01
LONG TERM /TUESDAY THROUGH SUNDAY/...
COLD FRONT AND ASSOCIATED PRECIP WILL EXIT THE SW CWFA EARLY ON
TUESDAY. DRY AND COOLER THAN NORMAL TEMPS ARE EXPECTED TUESDAY
THROUGH WEDNESDAY NIGHT. A WARM FRONT OVER THE NORTHERN GULF OF
MEXICO WILL START MOVING NORTH TOWARDS THE COAST BY THE END OF THE
WEEK. CLOUDS AND PRECIP WILL INCREASE ACROSS THE REGION THURSDAY
INTO SATURDAY AS SEVERAL WAVES OF LOW PRESSURE MOVE EAST ALONG THE
BOUNDARY AS IT NEARS THE COAST. THE LAST HALF OF THE WEEKEND LOOKS
DRY AT THIS TIME.
NLISTEMAA
&&
.AVIATION...
06Z UPDATE...
MVFR CIGS DEVELOPING ACROSS MUCH OF THE AREA THIS MORNING...WITH
IFR ACROSS PORTIONS OF CENTRAL GA. -SHRA EXPECTED TO MOVE IN MID-
MORNING...WITH TS AND LOW VFR CIGS EXPECTED GENERALLY AFTER 18Z.
EXPECT TWO WAVES OF PRECIP...WITH THE FIRST THIS AFTERNOON WITH A
HIGHER TS POTENTIAL...AND THE SECOND OVERNIGHT WITH THE FRONTAL
PASSAGE...WITH LOWER TS CHANCES. SSE WINDS EXPECTED THROUGH
MORNING...THEN A SWITCH SW AND EVENTUALLY TO THE WEST WITH SPEEDS
OF 8-11KT.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS...EXCEPT HIGH CONFIDENCE ON WINDS.
31
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 65 50 65 37 / 90 90 10 5
ATLANTA 69 49 62 39 / 90 90 10 5
BLAIRSVILLE 59 43 55 32 / 90 90 10 10
CARTERSVILLE 68 48 62 36 / 90 90 10 10
COLUMBUS 72 56 68 42 / 80 60 10 10
GAINESVILLE 62 48 62 37 / 90 90 10 5
MACON 70 55 69 40 / 80 60 20 10
ROME 69 46 62 35 / 90 90 10 10
PEACHTREE CITY 69 51 64 36 / 80 80 10 10
VIDALIA 75 62 71 44 / 60 50 30 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...31
LONG TERM....DEESE
AVIATION...31
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
421 AM CDT MON MAR 18 2013
.DISCUSSION...
406 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH A
WINTRY MIX OF PRECIP ONGOING...AND THEN CONTINUING THROUGH THE
REMAINDER OF THE DAY WITH SNOW LIKELY ACROSS THE NORTHERN THIRD OF
THE CWA WHILE A RAIN/SNOW MIX FURTHER SOUTH TOWARDS THE I80
CORRIDOR...AND THEN ALL RAIN ACROSS THE SOUTHERN TIER OF COUNTIES.
LATEST RADAR IMAGERY IS DEPICTING AN AREA OF PRECIPITATION
SPREADING NORTH ACROSS PARTS OF NORTHEAST ILLINOIS AND NORTHWEST
INDIANA AS AN MID LEVEL WAVE TRACKS NORTHEAST ACROSS THE REGION.
LATEST REPORTS CONTINUE TO SUPPORT A WINTRY MIX THAT HAS BEEN
ANTICIPATED WITH SNOW OR SLEET FALLING ON THE NORTHERN FRINGE OF
THIS PRECIP SHIELD FROM STREATOR IN ILLINOIS EAST TO RENSSELAER IN
INDIANA...WHILE A RAIN SNOW MIX HAD BEEN REPORTED JUST SOUTH OF
THIS LINE. OVER THE NEXT COUPLE OF HOURS THIS TREND WILL LIKELY
CONTINUE AS THIS WINTRY MIX MOVES NORTH TOWARD THE CHICAGO METRO
AREA. ALTHOUGH WEAK...LATEST RAP ANALYSIS IS SHOWING SOME WAA
AIDING IN THIS DEVELOPMENT AND EXPECT THIS WEAK WAA TO FURTHER AID
THIS MORNING UNTIL MORE LARGE SCALE SUPPORT ARRIVES FROM THE WEST.
EXPECT SNOW OR SLEET WITH ONLY MINOR ACCUMULATIONS INITIALLY EARLY
THIS MORNING ALONG AND NORTH OF INTERSTATE 80...JUST SOUTH OF THE
INTERSTATE 80 CORRIDOR A RAIN SNOW MIX WILL BE LIKELY CONTINUE.
SURFACE TEMPS THIS MORNING HAVE BEEN SLOWLY FALLING WITH CURRENT
TEMPS AT OR JUST BELOW FREEZING ACROSS MUCH OF THE CWA. IN THOSE
AREAS WHERE LIGHT RAIN DOES OCCUR...THESE SURFACE TEMPERATURES
WILL SUPPORT THE POTENTIAL FOR BRIDGES AND ELEVATED ROADWAYS TO
ACCUMULATE A THIN LAYER OF ICING. ALTHOUGH THIS WINTRY MIX HAD
BEEN FALLING OVER THE LAST COUPLE OF HOURS...REPORTS HAD NOT
INDICATED ANY WIDESPREAD SLIPPERY CONDITIONS BUT WITH ROADS
REMAINING ONLY WET AT THAT TIME. WOULD SUSPECT THAT SLIPPERY
CONDITIONS ARE CURRENTLY DEVELOPING AND COULD POSSIBLY CONTINUE TO
DEVELOP OVER THE NEXT COUPLE OF HOURS. OF GREATEST CONCERN AT THIS
TIME FOR THESE SLIPPERY CONDITIONS WOULD BE THE I80 CORRIDOR WHERE
CURRENTLY THE STRONGEST RETURNS ON RADAR ARE LOCATED AS WELL AS
WITH SURFACE TEMPS JUST BELOW FREEZING. HAVE REISSUED AN SPS AT
THIS TIME FOR THOSE AREAS...WHILE NOT ISSUING ANY OTHER HEADLINES
AT THIS TIME. FORCING FOR THIS CURRENT PRECIP ACROSS THE CWA
SHOULD EXIT OVER THE NEXT COUPLE OF HOURS...WITH LATEST SHORT TERM
GUIDANCE SHOWING A DIMINISHING TREND WITHIN THE OVERALL EXTENT OF
THIS PRECIP. RESIDENCE TIME FOR ANY FURTHER LINGERING PRECIP IN
THESE AREAS SHOULD BE LIMITED THIS MORNING...AS THIS PRECIP AXIS
SLOWLY LIFTS NORTH. ALTHOUGH A DIMINISHING TREND HERE IN THE NEAR
TERM IS LIKELY...ONCE AGAIN STILL ANTICIPATE A NORTHWARD PUSH OF
THIS PRECIP.
LARGE SCALE FORCING FOR ASCENT WILL INCREASE THROUGH MID MORNING
AS THE CURRENT UPPER LEVEL TROUGH JUST TO THE WEST PUSHES EAST.
THIS IS ALREADY BEGINNING TO OCCUR OVER AREAS IN EASTERN IOWA
WHERE LIGHT RETURNS ARE BEGINNING TO SHOW UP ON RADAR. EXPECT
FURTHER DEVELOPMENT THROUGH MID TO LATE MORNING WITH A MIXED BAG
OF PRECIPITATION STILL LIKELY. ALTHOUGH...LATEST GUIDANCE IS
SHOWING THAT COLDER AIR WILL BE IN PLACE FURTHER SOUTH ACROSS THE
CWA THAN PREVIOUSLY ANTICIPATED WITH THE NUDGE OF WARMER AIR ALOFT
NOT AS PRONOUNCED FOR THIS MORNING OR MOST OF THE DAY...WITH
LATEST AMDAR SOUNDINGS SUPPORTED THESE THERMAL PROFILES. WITH THAT
IN MIND...HAVE SNOW OR SLEET POSSIBLE THROUGH MID MORNING FOR THE
NORTHERN HALF OF THE CWA ACROSS NORTH CENTRAL AND NORTHEAST
ILLINOIS WITH MORE LIQUID TYPE PRECIP EXPECTED FURTHER SOUTH.
SURFACE TEMPS WILL BE RISING THROUGH MID MORNING WITH ANY FURTHER
THREAT OF FREEZING RAIN IN THE CURRENT LOCATIONS BECOMING LESS
LIKELY. AS THIS UPPER LEVEL TROUGH SWINGS ACROSS THIS SNOW/SLEET
AND THEN SNOW THROUGH MID DAY AND EARLY AFTERNOON...DO THINK THERE
WILL BE SOME MINOR ACCUMULATIONS FOR AREAS ALONG AND NORTH OF THE
INTERSTATE 88 CORRIDOR INCLUDING THE WEST/NORTHWEST/NORTHERN
SUBURBS OF CHICAGO. ONE TO TWO INCHES WILL BE POSSIBLE NEAR THE
WISCONSIN BORDER WITH THREE INCHES AN OUTSIDE POSSIBILITY FOR
ISOLATED LOCATIONS...AND AROUND AN INCH FURTHER SOUTH. A TREND
TOWARDS MORE DRIZZLE WILL BE POSSIBLE BY MID AFTERNOON BUT AS THIS
OCCURS...MUCH COLDER AIR WILL BE SWEEPING THROUGH THE CWA. THIS
COULD HELP FOR FURTHER CRYSTALS TO DEVELOP AND HELP LIGHT SNOW TO
LINGER AROUND INTO THE AFTERNOON AND EARLY EVENING BUT WITH LITTLE
OR NO ADDITIONAL ACCUMULATION LIKELY. COLDER TEMPS STILL ON PAR
FOR THIS WEEK...STARTING OFF TONIGHT WITH LOW TO MID TEENS
POSSIBLE ACROSS MUCH OF THE CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* TIMING/TYPE OF PRECIPITATION THROUGH THE MORNING.
* MVFR/IFR CONDITIONS DEVELOPING THEN CONTINUING THROUGH THE
MORNING.
* GUSTY EAST WINDS NEAR 20 KT THROUGH AROUND
DAYBREAK...DIMINISHING AND BECOMING WEST-SOUTHWEST MIDDAY AND
INCREASING TO 20-30 KT BY THIS EVENING.
MDB
//DISCUSSION...UPDATED 09Z...
TRICKY PRECIP FORECAST CONTINUES THIS MORNING. BAND OF LIGHT
PRECIP CONTINUES TO MARCH NORTHWARD TOWARDS THE TERMINALS AND HAS
REACHED GYY AND WILL BE REACHING THE REMAINING TERMINALS IN THE
NEXT 1-2 HOURS. BASED ON SURFACE OBS SLEET SEEMS TO BE A DOMINANT
PRECIP TYPE BUT SUSPECT THAT SNOW IS MIXED IN AS WELL. HAVE SEEN
LITTLE IN THE WAY OF VSBY REDUCTION SUPPORTING THE LIGHT
INTENSITY. CIGS ARE ALSO LOWERING TO MVFR RATHER QUICKLY SO HAVE
ADJUSTED DOWNWARD CIG TREND TIMING SLIGHTLY. BASED ON LATEST TRENDS
AM EXPECTING THAT LIGHT PRECIP WILL CONTINUE ON AND OFF THROUGH
THE MORNING AS THERE HAS BEEN SOME REDEVELOPMENT ON THE SOUTHERN
PORTION OF THE APPROACHING BAND. AN EASTWARD MOVING BAND ACROSS
CENTRAL IOWA LOOKS TO ARRIVE LATE THIS MORNING AND MAY NOT EXIT
THE TERMINALS UNTIL EARLY AFTERNOON. WILL FURTHER EVALUATE BUT MAY
NEED TO INCLUDE STEADIER PRECIP UNTIL AROUND 20Z VS. THE CURRENT
-DZSN FROM 18-21. STILL APPEARS THAT MDW/GYY WILL HAVE THE BEST
CHANCE FOR SOME LIQUID PRECIP MIXED IN THROUGH THE MORNING AS NOSE
OF WARMER AIR PUSHES IN...WHERE ORD/DPA/RFD LOOK TO REMAIN MORE
SNOW/SLEET BUT IT MAY BE CLOSE AT ORD/DPA. WILL CONTINUE TO
MONITOR TRENDS AND ADJUST P-TYPE AS NEEDED.
MDB
FROM 06Z...
LOW PRESSURE OVER THE CENTRAL DAKOTAS WILL CONTINUE EASTWARD TO
LAKE SUPERIOR TODAY WHILE ANOTHER LOW NEAR THE MISSOURI BOOTHEEL
MOVES UP THE OHIO RIVER VALLEY. PRECIPITATION CONTINUES TO LIFT
NORTHWARD ACROSS CENTRAL ILLINOIS THOUGH THE BULK OF THIS IS
MOVING MORE TOWARDS THE NORTHEAST ACROSS CENTRAL INDIANA BUT
ADDITIONAL PRECIPITATION IS MOVING EASTWARD ACROSS CENTRAL IOWA.
PRECIPITATION WILL WORK INTO THE TERMINALS STARTING A FEW HOURS
FROM NOW. A MIX OF PRECIP TYPES IS EXPECTED AS WARMER AIR NOSES IN
ALOFT AND SURFACE TEMPS INITIALLY HOVER AROUND OR JUST BELOW
FREEZING BEFORE WARMING TOWARD MIDDAY. NORTHERN AREAS INCLUDING
ORD/RFD/DPA LOOK TO SEE PRIMARILY SNOW BUT SOME SLEET IS POSSIBLE
TOO AS WARM AIR APPROACHES ALOFT. SOUTHERN AREAS INCLUDING MDW/GYY
LOOK TO HAVE MORE OF A MIX OF RAIN AND SNOW WITH FREEZING RAIN
POSSIBLE THROUGH MID MORNING...AT LEAST AT TIMES...BEFORE SURFACE
TEMPS WARM ABOVE FREEZING. THE BULK OF THE PRECIPITATION IS
EXPECTED TO FALL PRIOR TO 18-20Z WHEN MID LEVEL MOISTURE AND
FORCING DIMINISHES...BUT SOME DRIZZLE MAY LINGER THROUGH EARLY
AFTERNOON. SOME SLUSHY ACCUMULATION IS POSSIBLE...ESPECIALLY
TOWARD RFD WHERE TEMPS WILL BE COLDEST OVERALL AND THIS WOULD
MAINLY ACCUMULATE DURING THE MORNING.
EAST-SOUTHEAST WINDS WILL CONTINUE WITH GUSTS TO AROUND 20 KT AT
TIMES THROUGH DAYBREAK BUT SPEEDS SHOULD EASE UP MID/LATE MORNING
BEFORE WINDS SHIFT TO THE SOUTHWEST THEN WEST THIS AFTERNOON. A
STRONG PUSH OF COLDER AIR WILL PUSH TEMPS BACK BELOW FREEZING LATE
IN THE DAY/THIS EVENING WITH STEEP LAPSE RATES SUPPORTING SOME
RENEWED SNOW FLURRY/SNOW SHOWER DEVELOPMENT BY EVENING WHICH MAY
CONTINUE OVERNIGHT AS WELL. WIND SPEEDS WILL ALSO PICK UP AS WINDS
SHIFT LATE IN THE DAY WITH GUSTS INCREASING TO AROUND 30 IF NOT 35
KTS FOR THE EVENING AND OVERNIGHT.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM CONFIDENCE IN TIMING/TRENDS AND TYPE OF PRECIP.
* MEDIUM CONFIDENCE IN PERIOD OF PREVAILING IFR CIG/VIS DURING
MORNING/MIDDAY.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY THROUGH SATURDAY...MAINLY VFR. GUSTY WEST WINDS TUE.
RATZER
&&
.MARINE...
323 AM CDT
LOW PRESSURE CONTINUES TO MOVE EAST ACROSS THE EASTERN DAKOTAS AND
WILL REACH EASTERN LAKE SUPERIOR TUESDAY MORNING. ANOTHER LOW IS
ALSO MOVING UP THE OHIO RIVER VALLEY AND WILL MERGE WITH THE MAIN
LOW TUESDAY. EAST TO SOUTHEAST WINDS CONTINUE ACROSS LAKE MICHIGAN
THIS MORNING WITH THE STRONGEST SPEEDS ACROSS THE CENTRAL SECTION OF
THE LAKE. THE PRESSURE GRADIENT WILL WEAKEN THROUGH THE MORNING
ALLOWING SPEEDS TO EASE UP WITH WINDS THEN SHIFTING TO THE WEST AND
SOUTHWEST THROUGH THE AFTERNOON. THE WEAKENING WINDS AND SHIFT IN
DIRECTION SHOULD HELP TO KNOCK WAVES DOWN SO WILL PLAN ON LETTING
THE SMALL CRAFT ADVISORY FOR THE ILLINOIS NEARSHORE WATERS EXPIRE AT
18Z. WEST WINDS WILL RAMP UP TO 35-40 KT GALES ACROSS THE SOUTHERN
TWO-THIRDS OF THE LAKE THIS EVENING WITH THE FAR NORTHERN SECTION
LIKELY BEING HELD TO AROUND 30 KT THANKS TO THE NEARBY PASSAGE OF
THE SURFACE LOW TONIGHT. HAVE UPGRADED THE GALE WATCH TO A GALE
WARNING FOR THE OPEN WATERS. ISSUED A GALE WATCH FOR THE ILLINOIS
NEARSHORE WATERS AS WELL AS THE INDIANA WATERS FROM CALUMET HARBOR
TO GARY...WITH SOME UNCERTAINTY ON WHETHER GALE FORCE WILL BE ABLE
TO BE REACHED GIVEN THE OFFSHORE WIND COMPONENT. HOWEVER...DID
UPGRADE AREAS FROM GARY EAST TO A GALE WARNING GIVEN THEIR BETTER
ONSHORE EXPOSURE. OTHERWISE...TEMPERATURES WILL FALL AS MUCH COLDER
AIR BUILDS IN WHICH WILL SET THE STAGE FOR FREEZING SPRAY. THE LOW
WILL BE SLOW TO DEPART TO THE EAST WHILE HIGH PRESSURE SPREADS INTO
THE NORTHERN PLAINS INTO TUESDAY NIGHT. THIS WILL KEEP WINDS STRONG
INTO TUESDAY EVENING BUT SPEEDS LOOK TO FALL JUST BELOW GALE FORCE
TUESDAY EVENING OR TUESDAY NIGHT...BUT SOME GALE FORCE GUSTS MAY
CONTINUE EVEN THROUGH WEDNESDAY. WILL KEEP 30 KT IN THE FORECAST FOR
THIS TIME FRAME FOR NOW THOUGH. THE PRESSURE GRADIENT WILL GRADUALLY
WEAKEN THROUGH THURSDAY AS THE LOW FILLS TO THE EAST AND THE HIGH
BROADENS TO THE WEST. NORTHEASTERLY LOW LEVEL FLOW LOOKS TO SET UP
NEXT WEEKEND WITH THE MAIN TRACK OF LOW PRESSURE SYSTEMS POSITIONED
SOUTH OF THE LAKE.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
GALE WATCH...LMZ740-LMZ741-LMZ742-LMZ743...10 PM MONDAY TO 9 PM
TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
407 AM CDT MON MAR 18 2013
.DISCUSSION...
406 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH A
WINTRY MIX OF PRECIP ONGOING...AND THEN CONTINUING THROUGH THE
REMAINDER OF THE DAY WITH SNOW LIKELY ACROSS THE NORTHERN THIRD OF
THE CWA WHILE A RAIN/SNOW MIX FURTHER SOUTH TOWARDS THE I80
CORRIDOR...AND THEN ALL RAIN ACROSS THE SOUTHERN TIER OF COUNTIES.
LATEST RADAR IMAGERY IS DEPICTING AN AREA OF PRECIPITATION
SPREADING NORTH ACROSS PARTS OF NORTHEAST ILLINOIS AND NORTHWEST
INDIANA AS AN MID LEVEL WAVE TRACKS NORTHEAST ACROSS THE REGION.
LATEST REPORTS CONTINUE TO SUPPORT A WINTRY MIX THAT HAS BEEN
ANTICIPATED WITH SNOW OR SLEET FALLING ON THE NORTHERN FRINGE OF
THIS PRECIP SHIELD FROM STREATOR IN ILLINOIS EAST TO RENSSELAER IN
INDIANA...WHILE A RAIN SNOW MIX HAD BEEN REPORTED JUST SOUTH OF
THIS LINE. OVER THE NEXT COUPLE OF HOURS THIS TREND WILL LIKELY
CONTINUE AS THIS WINTRY MIX MOVES NORTH TOWARD THE CHICAGO METRO
AREA. ALTHOUGH WEAK...LATEST RAP ANALYSIS IS SHOWING SOME WAA
AIDING IN THIS DEVELOPMENT AND EXPECT THIS WEAK WAA TO FURTHER AID
THIS MORNING UNTIL MORE LARGE SCALE SUPPORT ARRIVES FROM THE WEST.
EXPECT SNOW OR SLEET WITH ONLY MINOR ACCUMULATIONS INITIALLY EARLY
THIS MORNING ALONG AND NORTH OF INTERSTATE 80...JUST SOUTH OF THE
INTERSTATE 80 CORRIDOR A RAIN SNOW MIX WILL BE LIKELY CONTINUE.
SURFACE TEMPS THIS MORNING HAVE BEEN SLOWLY FALLING WITH CURRENT
TEMPS AT OR JUST BELOW FREEZING ACROSS MUCH OF THE CWA. IN THOSE
AREAS WHERE LIGHT RAIN DOES OCCUR...THESE SURFACE TEMPERATURES
WILL SUPPORT THE POTENTIAL FOR BRIDGES AND ELEVATED ROADWAYS TO
ACCUMULATE A THIN LAYER OF ICING. ALTHOUGH THIS WINTRY MIX HAD
BEEN FALLING OVER THE LAST COUPLE OF HOURS...REPORTS HAD NOT
INDICATED ANY WIDESPREAD SLIPPERY CONDITIONS BUT WITH ROADS
REMAINING ONLY WET AT THAT TIME. WOULD SUSPECT THAT SLIPPERY
CONDITIONS ARE CURRENTLY DEVELOPING AND COULD POSSIBLY CONTINUE TO
DEVELOP OVER THE NEXT COUPLE OF HOURS. OF GREATEST CONCERN AT THIS
TIME FOR THESE SLIPPERY CONDITIONS WOULD BE THE I80 CORRIDOR WHERE
CURRENTLY THE STRONGEST RETURNS ON RADAR ARE LOCATED AS WELL AS
WITH SURFACE TEMPS JUST BELOW FREEZING. HAVE REISSUED AN SPS AT
THIS TIME FOR THOSE AREAS...WHILE NOT ISSUING ANY OTHER HEADLINES
AT THIS TIME. FORCING FOR THIS CURRENT PRECIP ACROSS THE CWA
SHOULD EXIT OVER THE NEXT COUPLE OF HOURS...WITH LATEST SHORT TERM
GUIDANCE SHOWING A DIMINISHING TREND WITHIN THE OVERALL EXTENT OF
THIS PRECIP. RESIDENCE TIME FOR ANY FURTHER LINGERING PRECIP IN
THESE AREAS SHOULD BE LIMITED THIS MORNING...AS THIS PRECIP AXIS
SLOWLY LIFTS NORTH. ALTHOUGH A DIMINISHING TREND HERE IN THE NEAR
TERM IS LIKELY...ONCE AGAIN STILL ANTICIPATE A NORTHWARD PUSH OF
THIS PRECIP.
LARGE SCALE FORCING FOR ASCENT WILL INCREASE THROUGH MID MORNING
AS THE CURRENT UPPER LEVEL TROUGH JUST TO THE WEST PUSHES EAST.
THIS IS ALREADY BEGINNING TO OCCUR OVER AREAS IN EASTERN IOWA
WHERE LIGHT RETURNS ARE BEGINNING TO SHOW UP ON RADAR. EXPECT
FURTHER DEVELOPMENT THROUGH MID TO LATE MORNING WITH A MIXED BAG
OF PRECIPITATION STILL LIKELY. ALTHOUGH...LATEST GUIDANCE IS
SHOWING THAT COLDER AIR WILL BE IN PLACE FURTHER SOUTH ACROSS THE
CWA THAN PREVIOUSLY ANTICIPATED WITH THE NUDGE OF WARMER AIR ALOFT
NOT AS PRONOUNCED FOR THIS MORNING OR MOST OF THE DAY...WITH
LATEST AMDAR SOUNDINGS SUPPORTED THESE THERMAL PROFILES. WITH THAT
IN MIND...HAVE SNOW OR SLEET POSSIBLE THROUGH MID MORNING FOR THE
NORTHERN HALF OF THE CWA ACROSS NORTH CENTRAL AND NORTHEAST
ILLINOIS WITH MORE LIQUID TYPE PRECIP EXPECTED FURTHER SOUTH.
SURFACE TEMPS WILL BE RISING THROUGH MID MORNING WITH ANY FURTHER
THREAT OF FREEZING RAIN IN THE CURRENT LOCATIONS BECOMING LESS
LIKELY. AS THIS UPPER LEVEL TROUGH SWINGS ACROSS THIS SNOW/SLEET
AND THEN SNOW THROUGH MID DAY AND EARLY AFTERNOON...DO THINK THERE
WILL BE SOME MINOR ACCUMULATIONS FOR AREAS ALONG AND NORTH OF THE
INTERSTATE 88 CORRIDOR INCLUDING THE WEST/NORTHWEST/NORTHERN
SUBURBS OF CHICAGO. ONE TO TWO INCHES WILL BE POSSIBLE NEAR THE
WISCONSIN BORDER WITH THREE INCHES AN OUTSIDE POSSIBILITY FOR
ISOLATED LOCATIONS...AND AROUND AN INCH FURTHER SOUTH. A TREND
TOWARDS MORE DRIZZLE WILL BE POSSIBLE BY MID AFTERNOON BUT AS THIS
OCCURS...MUCH COLDER AIR WILL BE SWEEPING THROUGH THE CWA. THIS
COULD HELP FOR FURTHER CRYSTALS TO DEVELOP AND HELP LIGHT SNOW TO
LINGER AROUND INTO THE AFTERNOON AND EARLY EVENING BUT WITH LITTLE
OR NO ADDITIONAL ACCUMULATION LIKELY. COLDER TEMPS STILL ON PAR
FOR THIS WEEK...STARTING OFF TONIGHT WITH LOW TO MID TEENS
POSSIBLE ACROSS MUCH OF THE CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* TIMING/TYPE OF PRECIPITATION EARLY THIS MORNING...MIXED PRECIP
LIKELY...ESPECIALLY MDW.
* MVFR/IFR CONDITIONS DEVELOPING DURING THE MORNING.
* GUSTY EAST WINDS NEAR 20 KT THROUGH AROUND
DAYBREAK...DIMINISHING AND BECOMING WEST-SOUTHWEST MIDDAY AND
INCREASING TO 20-30 KT BY THIS EVENING.
MDB
//DISCUSSION...UPDATED 06Z...
LOW PRESSURE OVER THE CENTRAL DAKOTAS WILL CONTINUE EASTWARD TO
LAKE SUPERIOR TODAY WHILE ANOTHER LOW NEAR THE MISSOURI BOOTHEEL
MOVES UP THE OHIO RIVER VALLEY. PRECIPITATION CONTINUES TO LIFT
NORTHWARD ACROSS CENTRAL ILLINOIS THOUGH THE BULK OF THIS IS
MOVING MORE TOWARDS THE NORTHEAST ACROSS CENTRAL INDIANA BUT
ADDITIONAL PRECIPITATION IS MOVING EASTWARD ACROSS CENTRAL IOWA.
PRECIPITATION WILL WORK INTO THE TERMINALS STARTING A FEW HOURS
FROM NOW. A MIX OF PRECIP TYPES IS EXPECTED AS WARMER AIR NOSES IN
ALOFT AND SURFACE TEMPS INITIALLY HOVER AROUND OR JUST BELOW
FREEZING BEFORE WARMING TOWARD MIDDAY. NORTHERN AREAS INCLUDING
ORD/RFD/DPA LOOK TO SEE PRIMARILY SNOW BUT SOME SLEET IS POSSIBLE
TOO AS WARM AIR APPROACHES ALOFT. SOUTHERN AREAS INCLUDING MDW/GYY
LOOK TO HAVE MORE OF A MIX OF RAIN AND SNOW WITH FREEZING RAIN
POSSIBLE THROUGH MID MORNING...AT LEAST AT TIMES...BEFORE SURFACE
TEMPS WARM ABOVE FREEZING. THE BULK OF THE PRECIPITATION IS
EXPECTED TO FALL PRIOR TO 18-20Z WHEN MID LEVEL MOISTURE AND
FORCING DIMINISHES...BUT SOME DRIZZLE MAY LINGER THROUGH EARLY
AFTERNOON. SOME SLUSHY ACCUMULATION IS POSSIBLE...ESPECIALLY
TOWARD RFD WHERE TEMPS WILL BE COLDEST OVERALL AND THIS WOULD
MAINLY ACCUMULATE DURING THE MORNING.
EAST-SOUTHEAST WINDS WILL CONTINUE WITH GUSTS TO AROUND 20 KT AT
TIMES THROUGH DAYBREAK BUT SPEEDS SHOULD EASE UP MID/LATE MORNING
BEFORE WINDS SHIFT TO THE SOUTHWEST THEN WEST THIS AFTERNOON. A
STRONG PUSH OF COLDER AIR WILL PUSH TEMPS BACK BELOW FREEZING LATE
IN THE DAY/THIS EVENING WITH STEEP LAPSE RATES SUPPORTING SOME
RENEWED SNOW FLURRY/SNOW SHOWER DEVELOPMENT BY EVENING WHICH MAY
CONTINUE OVERNIGHT AS WELL. WIND SPEEDS WILL ALSO PICK UP AS WINDS
SHIFT LATE IN THE DAY WITH GUSTS INCREASING TO AROUND 30 IF NOT 35
KTS FOR THE EVENING AND OVERNIGHT.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE IN TIMING/TRENDS AND TYPE OF PRECIP.
* MEDIUM CONFIDENCE IN PERIOD OF PREVAILING IFR CIG/VIS DURING
MONDAY MORNING/MIDDAY.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY THROUGH SATURDAY...MAINLY VFR. GUSTY WEST WINDS TUE.
RATZER
&&
.MARINE...
323 AM CDT
LOW PRESSURE CONTINUES TO MOVE EAST ACROSS THE EASTERN DAKOTAS AND
WILL REACH EASTERN LAKE SUPERIOR TUESDAY MORNING. ANOTHER LOW IS
ALSO MOVING UP THE OHIO RIVER VALLEY AND WILL MERGE WITH THE MAIN
LOW TUESDAY. EAST TO SOUTHEAST WINDS CONTINUE ACROSS LAKE MICHIGAN
THIS MORNING WITH THE STRONGEST SPEEDS ACROSS THE CENTRAL SECTION OF
THE LAKE. THE PRESSURE GRADIENT WILL WEAKEN THROUGH THE MORNING
ALLOWING SPEEDS TO EASE UP WITH WINDS THEN SHIFTING TO THE WEST AND
SOUTHWEST THROUGH THE AFTERNOON. THE WEAKENING WINDS AND SHIFT IN
DIRECTION SHOULD HELP TO KNOCK WAVES DOWN SO WILL PLAN ON LETTING
THE SMALL CRAFT ADVISORY FOR THE ILLINOIS NEARSHORE WATERS EXPIRE AT
18Z. WEST WINDS WILL RAMP UP TO 35-40 KT GALES ACROSS THE SOUTHERN
TWO-THIRDS OF THE LAKE THIS EVENING WITH THE FAR NORTHERN SECTION
LIKELY BEING HELD TO AROUND 30 KT THANKS TO THE NEARBY PASSAGE OF
THE SURFACE LOW TONIGHT. HAVE UPGRADED THE GALE WATCH TO A GALE
WARNING FOR THE OPEN WATERS. ISSUED A GALE WATCH FOR THE ILLINOIS
NEARSHORE WATERS AS WELL AS THE INDIANA WATERS FROM CALUMET HARBOR
TO GARY...WITH SOME UNCERTAINTY ON WHETHER GALE FORCE WILL BE ABLE
TO BE REACHED GIVEN THE OFFSHORE WIND COMPONENT. HOWEVER...DID
UPGRADE AREAS FROM GARY EAST TO A GALE WARNING GIVEN THEIR BETTER
ONSHORE EXPOSURE. OTHERWISE...TEMPERATURES WILL FALL AS MUCH COLDER
AIR BUILDS IN WHICH WILL SET THE STAGE FOR FREEZING SPRAY. THE LOW
WILL BE SLOW TO DEPART TO THE EAST WHILE HIGH PRESSURE SPREADS INTO
THE NORTHERN PLAINS INTO TUESDAY NIGHT. THIS WILL KEEP WINDS STRONG
INTO TUESDAY EVENING BUT SPEEDS LOOK TO FALL JUST BELOW GALE FORCE
TUESDAY EVENING OR TUESDAY NIGHT...BUT SOME GALE FORCE GUSTS MAY
CONTINUE EVEN THROUGH WEDNESDAY. WILL KEEP 30 KT IN THE FORECAST FOR
THIS TIME FRAME FOR NOW THOUGH. THE PRESSURE GRADIENT WILL GRADUALLY
WEAKEN THROUGH THURSDAY AS THE LOW FILLS TO THE EAST AND THE HIGH
BROADENS TO THE WEST. NORTHEASTERLY LOW LEVEL FLOW LOOKS TO SET UP
NEXT WEEKEND WITH THE MAIN TRACK OF LOW PRESSURE SYSTEMS POSITIONED
SOUTH OF THE LAKE.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
GALE WATCH...LMZ740-LMZ741-LMZ742-LMZ743...10 PM MONDAY TO 9 PM
TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
324 AM CDT MON MAR 18 2013
.DISCUSSION...
838 PM CDT
UPDATE FOR REST OF TONIGHT...MINIMAL TWEAKING OF GRIDS DONE
OTHERWISE NO CHANGE TO FORECAST. BESIDES 21Z SREF AN RAP RUNS...
WHICH SUPPORT GOING FORECAST...NO NEW MODEL OUTPUT YET TO SEE IF
ANY SIGNIFICANT DEVIATIONS FROM EARLIER RUNS SO NO CHANGES MADE
AT THIS TIME.
TRS
//PREV DISCUSSION...
315 PM CDT
THE FORECAST CHALLENGES REMAIN FIRST ON THE LIKELIHOOD FOR SOME
LIGHT WINTRY PRECIP IN PLACES TONIGHT AND THEN LIGHT SNOW
ACCUMULATIONS ACROSS FAR NORTHERN ILLINOIS ON MONDAY...FOLLOWED BY
WHAT WILL BECOME THE BIG STORY AND THAT IS WELL BELOW NORMAL
TEMPERATURES FROM TUESDAY THROUGH THE END OF THE WORKWEEK.
SYNOPSIS...THE POLAR VORTEX OVER HUDSON BAY DURING MUCH OF LAST
WEEK HAS SHIFTED EAST...TEMPORARILY...ALLOWING FOR A FASTER PACED
DISTURBED FLOW TO HAVE EVOLVED INTO THE MIDDLE OF THE COUNTRY
TODAY. ONE SHORT WAVE IMPULSE OVER THE OZARKS THIS AFTERNOON IS
MOVING NORTHEAST SPREADING A VEIL OF HIGH CLOUDS ACROSS PART OF
THE AREA. THIS WILL BE THE SYSTEM TO BRING LIGHT PRECIP LATER
TONIGHT AS IT CONTINUES ALONG ITS TRACK. FURTHER WEST...A WELL-
DEFINED UPPER LEVEL JET IS MOVING EAST ACROSS THE WESTERN CONUS
AND USHERING A PRONOUNCED UPPER WAVE ACROSS EASTERN WY THIS
AFTERNOON. THIS WILL BE THE MONDAY MORNING INTO EARLY AFTERNOON
PRECIP MAKER AND BRING A POWERFUL COLD FRONT THROUGH MONDAY
EVE. THIS SYSTEM WILL CATCH UP WITH ITS PREDECESSOR ALLOWING
PHASING AND AN OVERALL IMPRESSIVE SYSTEM DEEPENING AND ORGANIZATION
OVER THE GREAT LAKES MONDAY NIGHT INTO TUESDAY. A MASSIVE
ANOMALOUSLY DEEP CLOSED UPPER LOW WILL BE THE RESULT. WITH FURTHER
BLOCKING UPSTREAM OVER THE NORTH ATLANTIC...THIS WILL MOVE LITTLE
THUS SUSTAINING NORTHWEST FLOW OVER THE REGION WITH REGULAR
REINFORCING SHOTS OF REALLY COLD AIR BY MARCH STANDARDS.
TONIGHT...MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THE SHORT
WAVE OVER MO MOVING NORTHEAST AND BRINGING WITH IT THE ONGOING
WARM MOIST ADVECTION ALOFT THAT HAS PRODUCED PRECIP DOWNSTATE
TODAY. MODEL DIFFERENCES REMAIN IN PRECIP TYPE WHICH CAN BE
EXPECTED WITH HOW CLOSE TO 0C A GOOD PART OF THE FORECAST THERMAL
PROFILES ARE. VARIOUS WRF AND ARW MODELS INDICATE PRECIP SHOULD
SLOWLY SPREAD NORTHWARD THROUGH CENTRAL IL THIS EVE AND FORECAST
ISENTROPIC SURFACES AND ELEVATED MOISTURE CONVERGENCE FROM BOTH
THE RAP AND NAM AGREE WITH THIS DEPICTION. SOME FLURRIES/DRIZZLE
AHEAD OF THE MAIN PRECIP AREA ARE POSSIBLE AS THE ATMOSPHERE
SATURATES.
THERE ARE SEVERAL CULPRITS FOR THE PRECIP TYPE QUESTIONS. FOR
ONE...BECAUSE THE AREA IS GRAZED BY THE LEAD SHORT WAVE AND ITS
DEEPER SATURATION...THERE IS UNCERTAINTY ON WHETHER ICE CRYSTALS
ARE INTRODUCED. SECOND...THERE IS A SEVERAL THOUSAND FT DEEP
LAYER AROUND 0C FORECAST ACROSS A LARGE PART OF THE AREA AS PRECIP
SPREADS IN. AND FINALLY...SURFACE TEMPERATURES ARE LIKELY TO HOLD
STEADY THROUGH LATE EVE AND OVERNIGHT...AND MAY EVEN INCH UP IN
THE FAR SOUTH DEPENDING ON PRECIP STRENGTH...WHICH PRIMARILY LOOKS
LIGHT.
WHILE THERE MAY BE LIGHT SNOW IN THE ONSET SOUTH OF I-80 THIS EVE
AS THE WARM NOSE IS MARGINAL...IT APPEARS THAT BY OVERNIGHT THIS
LAYER WILL BE DEEP ENOUGH TO SUPPORT FULL MELTING. THE MOISTURE
TRANSPORT NOSE FROM THE SHORT WAVE POINTS INTO THE SOUTHEAST
FORECAST AREA...AND DO HAVE AROUND ONE TENTH OF AN INCH OF QPF.
SURFACE TEMPERATURES LOOK TO BE JUST ABOVE FREEZING THERE...BUT
WILL NEED TO BE WATCHED CLOSELY. FURTHER TO THE NORTH...TOWARD
I-80 AND EVEN SOMEWHAT NORTH FROM THERE...QPF LOOKS TO BE LIGHT
OVERNIGHT...BUT PROFILES DO SUPPORT LIGHT FREEZING RAIN OR SLEET
DEPENDING ON WHICH MODEL. THIS DOES INCLUDE FOR DOWNTOWN CHICAGO.
TOWARD FAR NORTHERN IL...THE PROFILES BECOME COOL ENOUGH THAT THE
TYPE SHOULD BE SLEET OR SNOW...BUT AGAIN PRIOR TO DAYBREAK THIS
LOOKS TO BE LIGHT.
AS THE MAIN UPPER WAVE APPROACHES MONDAY MORNING...GUIDANCE
AGREES ON THIS BEING THE STRONGEST PERIOD OF OMEGA/QG FORCING FOR
THE NORTHERN AREA. BECAUSE OF THIS FORCING AND THE ALREADY VERY
MARGINAL PROFILES FOR ANYTHING BUT SNOW THAT FAR NORTH...PRECIP
TYPE LOOKS TO TRANSITION TO A WET SNOW. THE HIGHER RATES SHOULD BE
TO THE NORTH OF THE CWA BUT ENOUGH SUPPORT WITH 31F-33F SURFACE
TEMPERATURES TO SUPPORT UP TO A COUPLE INCHES OF SNOW NEAR THE WI
BORDER. THE BEST TIMING FOR CHICAGO LOOKS TO BE FROM MID TO LATE
MORNING INTO EARLY AFTERNOON...WITH A DUSTING SOUTH TO ONE TO TWO
INCHES IN THE NORTH. STRONG DRYING IN THE MID-LEVELS IS FORECAST
TO FLOOD OVER THE AREA DURING THE AFTERNOON...CUTTING OFF MOST OF
THE FORCING FOR PRECIP. THIS WILL ALLOW TEMPERATURES TO MODERATE
ACROSS MUCH OF THE AREA BEFORE THE INCOMING PLUNGE...AND ITS
POSSIBLE MID 40S ARE REACHED SOUTH OF I-80 DEPENDING ON DEGREE OF
SCATTERING.
BY EARLY MONDAY EVE THE SYSTEMS COLD FRONT WILL BE SWEEPING ACROSS
NORTH CENTRAL IL. THE TEMPERATURE DROP LOOKS TO BE SHARP FOR THE
FIRST COUPLE HOURS AFTER THE FRONT AND HAVE TRIED TO MASSAGE SOME
OF THAT INTO THE HOURLY FORECAST GRIDS GIVEN THE HIGH CONFIDENCE
ALREADY. WITH THE MIXED BOUNDARY LAYER AND STRONG ISALLOBARIC
COMPONENT FORECAST...WINDS LOOK TO BE GUSTING TO 30 AND MAYBE EVEN
40 MPH /ESPECIALLY RIGHT AFTER FROPA/. THE CIPS ANALOG GUIDANCE
DOES HAVE A MAJORITY OF ITS MATCHES FAVORING GUSTS THAT HIGH IN
THE REGION. WIND CHILLS ARE EXPECTED TO FREE FALL INTO THE SINGLE
DIGITS BY MID EVE...AND THEN BELOW ZERO IN NORTHERN AREAS
OVERNIGHT. AS THE UPPER LOW MOVES ACROSS WI...ITS SOUTHERN FLANK
OF MID-LEVEL COLD AIR ADVECTION AND WRAPAROUND LOW-LEVEL MOISTURE
MAY BE ENOUGH TO SUPPORT FLURRIES OR EVEN SHOW SHOWERS. WHILE THIS
WILL BE LIGHT GIVEN LIMITED OVERALL FORCING...WITH THE GUSTY WINDS
AND THE LOWERING WATER CONTENT OF THE SNOW...THERE MAY BE SOME
MARKEDLY REDUCED VISIBILITIES IF AND WHERE SOME OF THIS SNOW
IS ABLE MATERIALIZE ACROSS FAR NORTHERN IL MONDAY EVE.
FOR TUESDAY AND BEYOND...THE COLD AIR ADVECTION CONTINUES TO
REINFORCE ITSELF WITH MULTIPLE COLD FRONTS AND MASSIVE CYCLONIC
FLOW. THIS FLOW WILL KEEP THE POTENTIAL FOR AT LEAST
STRATOCU...ALONG WITH THE CHANCE FOR SNOW SHOWERS.
HOWEVER...TEMPERATURES WERE THE FOCUS...AND THEY LOOK TO BE
REMARKABLY LOW FOR THE LATTER HALF OF MARCH. 850MB TEMPERATURES
ARE FORECAST TO DROP TO AROUND -15C TUE MORNING AND THEN AGAIN WED
MORNING. THE SURFACE WIND COMPONENT REMAINS ELEVATED THROUGH
WED...BUT STILL NIGHTTIME TEMPERATURES WILL FALL INTO THE TEENS
AREA WIDE THANKS TO THE COLD AIR ADVECTION. HIGHS WILL NOT REBOUND
MUCH...AND IN SOME PLACES WILL REMAIN BELOW 30F ON WEDNESDAY. IN
FACT...THE LOW MAXIMUM TEMPERATURE RECORD FOR WED IN ROCKFORD OF
ONLY 22F LOOKS TO BE POTENTIALLY IN JEOPARDY. THE SURFACE
HIGH BUILDS IN LATER THU THROUGH THE EARLY PART OF THE WEEKEND.
WITH THE BLOCKED FLOW...THE COLD AIR MASS HAS NO WHERE TO GO BUT
REINFORCE ITSELF FROM THE NORTH. AND ON THAT NOTE...BACKWARDS
TRAJECTORIES FROM THE GFS FOR WED INDICATE PARCELS ORIGINATING FROM
60 DEGREES NORTH LATITUDE /THE BORDER OF THE NORTHERN AND
SOUTHERN CANADIAN PROVINCES/. ALSO CONSIDERING THE EXTENT OF THE
SNOW COVER TO OUR NORTHWEST...WHICH WILL EXPAND TONIGHT INTO
MONDAY...LITTLE AIR MASS MODIFICATION IS ABLE TO OCCUR.
QUITE FASCINATING FOR LATE MARCH!
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* TIMING/TYPE OF PRECIPITATION EARLY THIS MORNING...MIXED PRECIP
LIKELY...ESPECIALLY MDW.
* MVFR/IFR CONDITIONS DEVELOPING DURING THE MORNING.
* GUSTY EAST WINDS NEAR 20 KT THROUGH AROUND
DAYBREAK...DIMINISHING AND BECOMING WEST-SOUTHWEST MIDDAY AND
INCREASING TO 20-30 KT BY THIS EVENING.
MDB
//DISCUSSION...UPDATED 06Z...
LOW PRESSURE OVER THE CENTRAL DAKOTAS WILL CONTINUE EASTWARD TO
LAKE SUPERIOR TODAY WHILE ANOTHER LOW NEAR THE MISSOURI BOOTHEEL
MOVES UP THE OHIO RIVER VALLEY. PRECIPITATION CONTINUES TO LIFT
NORTHWARD ACROSS CENTRAL ILLINOIS THOUGH THE BULK OF THIS IS
MOVING MORE TOWARDS THE NORTHEAST ACROSS CENTRAL INDIANA BUT
ADDITIONAL PRECIPITATION IS MOVING EASTWARD ACROSS CENTRAL IOWA.
PRECIPITATION WILL WORK INTO THE TERMINALS STARTING A FEW HOURS
FROM NOW. A MIX OF PRECIP TYPES IS EXPECTED AS WARMER AIR NOSES IN
ALOFT AND SURFACE TEMPS INITIALLY HOVER AROUND OR JUST BELOW
FREEZING BEFORE WARMING TOWARD MIDDAY. NORTHERN AREAS INCLUDING
ORD/RFD/DPA LOOK TO SEE PRIMARILY SNOW BUT SOME SLEET IS POSSIBLE
TOO AS WARM AIR APPROACHES ALOFT. SOUTHERN AREAS INCLUDING MDW/GYY
LOOK TO HAVE MORE OF A MIX OF RAIN AND SNOW WITH FREEZING RAIN
POSSIBLE THROUGH MID MORNING...AT LEAST AT TIMES...BEFORE SURFACE
TEMPS WARM ABOVE FREEZING. THE BULK OF THE PRECIPITATION IS
EXPECTED TO FALL PRIOR TO 18-20Z WHEN MID LEVEL MOISTURE AND
FORCING DIMINISHES...BUT SOME DRIZZLE MAY LINGER THROUGH EARLY
AFTERNOON. SOME SLUSHY ACCUMULATION IS POSSIBLE...ESPECIALLY
TOWARD RFD WHERE TEMPS WILL BE COLDEST OVERALL AND THIS WOULD
MAINLY ACCUMULATE DURING THE MORNING.
EAST-SOUTHEAST WINDS WILL CONTINUE WITH GUSTS TO AROUND 20 KT AT
TIMES THROUGH DAYBREAK BUT SPEEDS SHOULD EASE UP MID/LATE MORNING
BEFORE WINDS SHIFT TO THE SOUTHWEST THEN WEST THIS AFTERNOON. A
STRONG PUSH OF COLDER AIR WILL PUSH TEMPS BACK BELOW FREEZING LATE
IN THE DAY/THIS EVENING WITH STEEP LAPSE RATES SUPPORTING SOME
RENEWED SNOW FLURRY/SNOW SHOWER DEVELOPMENT BY EVENING WHICH MAY
CONTINUE OVERNIGHT AS WELL. WIND SPEEDS WILL ALSO PICK UP AS WINDS
SHIFT LATE IN THE DAY WITH GUSTS INCREASING TO AROUND 30 IF NOT 35
KTS FOR THE EVENING AND OVERNIGHT.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE IN TIMING/TRENDS AND TYPE OF PRECIP.
* MEDIUM CONFIDENCE IN PERIOD OF PREVAILING IFR CIG/VIS DURING
MONDAY MORNING/MIDDAY.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY THROUGH SATURDAY...MAINLY VFR. GUSTY WEST WINDS TUE.
RATZER
&&
.MARINE...
323 AM CDT
LOW PRESSURE CONTINUES TO MOVE EAST ACROSS THE EASTERN DAKOTAS AND
WILL REACH EASTERN LAKE SUPERIOR TUESDAY MORNING. ANOTHER LOW IS
ALSO MOVING UP THE OHIO RIVER VALLEY AND WILL MERGE WITH THE MAIN
LOW TUESDAY. EAST TO SOUTHEAST WINDS CONTINUE ACROSS LAKE MICHIGAN
THIS MORNING WITH THE STRONGEST SPEEDS ACROSS THE CENTRAL SECTION OF
THE LAKE. THE PRESSURE GRADIENT WILL WEAKEN THROUGH THE MORNING
ALLOWING SPEEDS TO EASE UP WITH WINDS THEN SHIFTING TO THE WEST AND
SOUTHWEST THROUGH THE AFTERNOON. THE WEAKENING WINDS AND SHIFT IN
DIRECTION SHOULD HELP TO KNOCK WAVES DOWN SO WILL PLAN ON LETTING
THE SMALL CRAFT ADVISORY FOR THE ILLINOIS NEARSHORE WATERS EXPIRE AT
18Z. WEST WINDS WILL RAMP UP TO 35-40 KT GALES ACROSS THE SOUTHERN
TWO-THIRDS OF THE LAKE THIS EVENING WITH THE FAR NORTHERN SECTION
LIKELY BEING HELD TO AROUND 30 KT THANKS TO THE NEARBY PASSAGE OF
THE SURFACE LOW TONIGHT. HAVE UPGRADED THE GALE WATCH TO A GALE
WARNING FOR THE OPEN WATERS. ISSUED A GALE WATCH FOR THE ILLINOIS
NEARSHORE WATERS AS WELL AS THE INDIANA WATERS FROM CALUMET HARBOR
TO GARY...WITH SOME UNCERTAINTY ON WHETHER GALE FORCE WILL BE ABLE
TO BE REACHED GIVEN THE OFFSHORE WIND COMPONENT. HOWEVER...DID
UPGRADE AREAS FROM GARY EAST TO A GALE WARNING GIVEN THEIR BETTER
ONSHORE EXPOSURE. OTHERWISE...TEMPERATURES WILL FALL AS MUCH COLDER
AIR BUILDS IN WHICH WILL SET THE STAGE FOR FREEZING SPRAY. THE LOW
WILL BE SLOW TO DEPART TO THE EAST WHILE HIGH PRESSURE SPREADS INTO
THE NORTHERN PLAINS INTO TUESDAY NIGHT. THIS WILL KEEP WINDS STRONG
INTO TUESDAY EVENING BUT SPEEDS LOOK TO FALL JUST BELOW GALE FORCE
TUESDAY EVENING OR TUESDAY NIGHT...BUT SOME GALE FORCE GUSTS MAY
CONTINUE EVEN THROUGH WEDNESDAY. WILL KEEP 30 KT IN THE FORECAST FOR
THIS TIME FRAME FOR NOW THOUGH. THE PRESSURE GRADIENT WILL GRADUALLY
WEAKEN THROUGH THURSDAY AS THE LOW FILLS TO THE EAST AND THE HIGH
BROADENS TO THE WEST. NORTHEASTERLY LOW LEVEL FLOW LOOKS TO SET UP
NEXT WEEKEND WITH THE MAIN TRACK OF LOW PRESSURE SYSTEMS POSITIONED
SOUTH OF THE LAKE.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
GALE WATCH...LMZ740-LMZ741-LMZ742-LMZ743...10 PM MONDAY TO 9 PM
TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
105 AM CDT MON MAR 18 2013
.DISCUSSION...
838 PM CDT
UPDATE FOR REST OF TONIGHT...MINIMAL TWEAKING OF GRIDS DONE
OTHERWISE NO CHANGE TO FORECAST. BESIDES 21Z SREF AN RAP RUNS...
WHICH SUPPORT GOING FORECAST...NO NEW MODEL OUTPUT YET TO SEE IF
ANY SIGNIFICANT DEVIATIONS FROM EARLIER RUNS SO NO CHANGES MADE
AT THIS TIME.
TRS
//PREV DISCUSSION...
315 PM CDT
THE FORECAST CHALLENGES REMAIN FIRST ON THE LIKELIHOOD FOR SOME
LIGHT WINTRY PRECIP IN PLACES TONIGHT AND THEN LIGHT SNOW
ACCUMULATIONS ACROSS FAR NORTHERN ILLINOIS ON MONDAY...FOLLOWED BY
WHAT WILL BECOME THE BIG STORY AND THAT IS WELL BELOW NORMAL
TEMPERATURES FROM TUESDAY THROUGH THE END OF THE WORKWEEK.
SYNOPSIS...THE POLAR VORTEX OVER HUDSON BAY DURING MUCH OF LAST
WEEK HAS SHIFTED EAST...TEMPORARILY...ALLOWING FOR A FASTER PACED
DISTURBED FLOW TO HAVE EVOLVED INTO THE MIDDLE OF THE COUNTRY
TODAY. ONE SHORT WAVE IMPULSE OVER THE OZARKS THIS AFTERNOON IS
MOVING NORTHEAST SPREADING A VEIL OF HIGH CLOUDS ACROSS PART OF
THE AREA. THIS WILL BE THE SYSTEM TO BRING LIGHT PRECIP LATER
TONIGHT AS IT CONTINUES ALONG ITS TRACK. FURTHER WEST...A WELL-
DEFINED UPPER LEVEL JET IS MOVING EAST ACROSS THE WESTERN CONUS
AND USHERING A PRONOUNCED UPPER WAVE ACROSS EASTERN WY THIS
AFTERNOON. THIS WILL BE THE MONDAY MORNING INTO EARLY AFTERNOON
PRECIP MAKER AND BRING A POWERFUL COLD FRONT THROUGH MONDAY
EVE. THIS SYSTEM WILL CATCH UP WITH ITS PREDECESSOR ALLOWING
PHASING AND AN OVERALL IMPRESSIVE SYSTEM DEEPENING AND ORGANIZATION
OVER THE GREAT LAKES MONDAY NIGHT INTO TUESDAY. A MASSIVE
ANOMALOUSLY DEEP CLOSED UPPER LOW WILL BE THE RESULT. WITH FURTHER
BLOCKING UPSTREAM OVER THE NORTH ATLANTIC...THIS WILL MOVE LITTLE
THUS SUSTAINING NORTHWEST FLOW OVER THE REGION WITH REGULAR
REINFORCING SHOTS OF REALLY COLD AIR BY MARCH STANDARDS.
TONIGHT...MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THE SHORT
WAVE OVER MO MOVING NORTHEAST AND BRINGING WITH IT THE ONGOING
WARM MOIST ADVECTION ALOFT THAT HAS PRODUCED PRECIP DOWNSTATE
TODAY. MODEL DIFFERENCES REMAIN IN PRECIP TYPE WHICH CAN BE
EXPECTED WITH HOW CLOSE TO 0C A GOOD PART OF THE FORECAST THERMAL
PROFILES ARE. VARIOUS WRF AND ARW MODELS INDICATE PRECIP SHOULD
SLOWLY SPREAD NORTHWARD THROUGH CENTRAL IL THIS EVE AND FORECAST
ISENTROPIC SURFACES AND ELEVATED MOISTURE CONVERGENCE FROM BOTH
THE RAP AND NAM AGREE WITH THIS DEPICTION. SOME FLURRIES/DRIZZLE
AHEAD OF THE MAIN PRECIP AREA ARE POSSIBLE AS THE ATMOSPHERE
SATURATES.
THERE ARE SEVERAL CULPRITS FOR THE PRECIP TYPE QUESTIONS. FOR
ONE...BECAUSE THE AREA IS GRAZED BY THE LEAD SHORT WAVE AND ITS
DEEPER SATURATION...THERE IS UNCERTAINTY ON WHETHER ICE CRYSTALS
ARE INTRODUCED. SECOND...THERE IS A SEVERAL THOUSAND FT DEEP
LAYER AROUND 0C FORECAST ACROSS A LARGE PART OF THE AREA AS PRECIP
SPREADS IN. AND FINALLY...SURFACE TEMPERATURES ARE LIKELY TO HOLD
STEADY THROUGH LATE EVE AND OVERNIGHT...AND MAY EVEN INCH UP IN
THE FAR SOUTH DEPENDING ON PRECIP STRENGTH...WHICH PRIMARILY LOOKS
LIGHT.
WHILE THERE MAY BE LIGHT SNOW IN THE ONSET SOUTH OF I-80 THIS EVE
AS THE WARM NOSE IS MARGINAL...IT APPEARS THAT BY OVERNIGHT THIS
LAYER WILL BE DEEP ENOUGH TO SUPPORT FULL MELTING. THE MOISTURE
TRANSPORT NOSE FROM THE SHORT WAVE POINTS INTO THE SOUTHEAST
FORECAST AREA...AND DO HAVE AROUND ONE TENTH OF AN INCH OF QPF.
SURFACE TEMPERATURES LOOK TO BE JUST ABOVE FREEZING THERE...BUT
WILL NEED TO BE WATCHED CLOSELY. FURTHER TO THE NORTH...TOWARD
I-80 AND EVEN SOMEWHAT NORTH FROM THERE...QPF LOOKS TO BE LIGHT
OVERNIGHT...BUT PROFILES DO SUPPORT LIGHT FREEZING RAIN OR SLEET
DEPENDING ON WHICH MODEL. THIS DOES INCLUDE FOR DOWNTOWN CHICAGO.
TOWARD FAR NORTHERN IL...THE PROFILES BECOME COOL ENOUGH THAT THE
TYPE SHOULD BE SLEET OR SNOW...BUT AGAIN PRIOR TO DAYBREAK THIS
LOOKS TO BE LIGHT.
AS THE MAIN UPPER WAVE APPROACHES MONDAY MORNING...GUIDANCE
AGREES ON THIS BEING THE STRONGEST PERIOD OF OMEGA/QG FORCING FOR
THE NORTHERN AREA. BECAUSE OF THIS FORCING AND THE ALREADY VERY
MARGINAL PROFILES FOR ANYTHING BUT SNOW THAT FAR NORTH...PRECIP
TYPE LOOKS TO TRANSITION TO A WET SNOW. THE HIGHER RATES SHOULD BE
TO THE NORTH OF THE CWA BUT ENOUGH SUPPORT WITH 31F-33F SURFACE
TEMPERATURES TO SUPPORT UP TO A COUPLE INCHES OF SNOW NEAR THE WI
BORDER. THE BEST TIMING FOR CHICAGO LOOKS TO BE FROM MID TO LATE
MORNING INTO EARLY AFTERNOON...WITH A DUSTING SOUTH TO ONE TO TWO
INCHES IN THE NORTH. STRONG DRYING IN THE MID-LEVELS IS FORECAST
TO FLOOD OVER THE AREA DURING THE AFTERNOON...CUTTING OFF MOST OF
THE FORCING FOR PRECIP. THIS WILL ALLOW TEMPERATURES TO MODERATE
ACROSS MUCH OF THE AREA BEFORE THE INCOMING PLUNGE...AND ITS
POSSIBLE MID 40S ARE REACHED SOUTH OF I-80 DEPENDING ON DEGREE OF
SCATTERING.
BY EARLY MONDAY EVE THE SYSTEMS COLD FRONT WILL BE SWEEPING ACROSS
NORTH CENTRAL IL. THE TEMPERATURE DROP LOOKS TO BE SHARP FOR THE
FIRST COUPLE HOURS AFTER THE FRONT AND HAVE TRIED TO MASSAGE SOME
OF THAT INTO THE HOURLY FORECAST GRIDS GIVEN THE HIGH CONFIDENCE
ALREADY. WITH THE MIXED BOUNDARY LAYER AND STRONG ISALLOBARIC
COMPONENT FORECAST...WINDS LOOK TO BE GUSTING TO 30 AND MAYBE EVEN
40 MPH /ESPECIALLY RIGHT AFTER FROPA/. THE CIPS ANALOG GUIDANCE
DOES HAVE A MAJORITY OF ITS MATCHES FAVORING GUSTS THAT HIGH IN
THE REGION. WIND CHILLS ARE EXPECTED TO FREE FALL INTO THE SINGLE
DIGITS BY MID EVE...AND THEN BELOW ZERO IN NORTHERN AREAS
OVERNIGHT. AS THE UPPER LOW MOVES ACROSS WI...ITS SOUTHERN FLANK
OF MID-LEVEL COLD AIR ADVECTION AND WRAPAROUND LOW-LEVEL MOISTURE
MAY BE ENOUGH TO SUPPORT FLURRIES OR EVEN SHOW SHOWERS. WHILE THIS
WILL BE LIGHT GIVEN LIMITED OVERALL FORCING...WITH THE GUSTY WINDS
AND THE LOWERING WATER CONTENT OF THE SNOW...THERE MAY BE SOME
MARKEDLY REDUCED VISIBILITIES IF AND WHERE SOME OF THIS SNOW
IS ABLE MATERIALIZE ACROSS FAR NORTHERN IL MONDAY EVE.
FOR TUESDAY AND BEYOND...THE COLD AIR ADVECTION CONTINUES TO
REINFORCE ITSELF WITH MULTIPLE COLD FRONTS AND MASSIVE CYCLONIC
FLOW. THIS FLOW WILL KEEP THE POTENTIAL FOR AT LEAST
STRATOCU...ALONG WITH THE CHANCE FOR SNOW SHOWERS.
HOWEVER...TEMPERATURES WERE THE FOCUS...AND THEY LOOK TO BE
REMARKABLY LOW FOR THE LATTER HALF OF MARCH. 850MB TEMPERATURES
ARE FORECAST TO DROP TO AROUND -15C TUE MORNING AND THEN AGAIN WED
MORNING. THE SURFACE WIND COMPONENT REMAINS ELEVATED THROUGH
WED...BUT STILL NIGHTTIME TEMPERATURES WILL FALL INTO THE TEENS
AREA WIDE THANKS TO THE COLD AIR ADVECTION. HIGHS WILL NOT REBOUND
MUCH...AND IN SOME PLACES WILL REMAIN BELOW 30F ON WEDNESDAY. IN
FACT...THE LOW MAXIMUM TEMPERATURE RECORD FOR WED IN ROCKFORD OF
ONLY 22F LOOKS TO BE POTENTIALLY IN JEOPARDY. THE SURFACE
HIGH BUILDS IN LATER THU THROUGH THE EARLY PART OF THE WEEKEND.
WITH THE BLOCKED FLOW...THE COLD AIR MASS HAS NO WHERE TO GO BUT
REINFORCE ITSELF FROM THE NORTH. AND ON THAT NOTE...BACKWARDS
TRAJECTORIES FROM THE GFS FOR WED INDICATE PARCELS ORIGINATING FROM
60 DEGREES NORTH LATITUDE /THE BORDER OF THE NORTHERN AND
SOUTHERN CANADIAN PROVINCES/. ALSO CONSIDERING THE EXTENT OF THE
SNOW COVER TO OUR NORTHWEST...WHICH WILL EXPAND TONIGHT INTO
MONDAY...LITTLE AIR MASS MODIFICATION IS ABLE TO OCCUR.
QUITE FASCINATING FOR LATE MARCH!
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* TIMING/TYPE OF PRECIPITATION EARLY THIS MORNING...MIXED PRECIP
LIKELY...ESPECIALLY MDW.
* MVFR/IFR CONDITIONS DEVELOPING DURING THE MORNING.
* GUSTY EAST WINDS NEAR 20 KT THROUGH AROUND
DAYBREAK...DIMINISHING AND BECOMING WEST-SOUTHWEST MIDDAY AND
INCREASING TO 20-30 KT BY THIS EVENING.
MDB
//DISCUSSION...UPDATED 06Z...
LOW PRESSURE OVER THE CENTRAL DAKOTAS WILL CONTINUE EASTWARD TO
LAKE SUPERIOR TODAY WHILE ANOTHER LOW NEAR THE MISSOURI BOOTHEEL
MOVES UP THE OHIO RIVER VALLEY. PRECIPITATION CONTINUES TO LIFT
NORTHWARD ACROSS CENTRAL ILLINOIS THOUGH THE BULK OF THIS IS
MOVING MORE TOWARDS THE NORTHEAST ACROSS CENTRAL INDIANA BUT
ADDITIONAL PRECIPITATION IS MOVING EASTWARD ACROSS CENTRAL IOWA.
PRECIPITATION WILL WORK INTO THE TERMINALS STARTING A FEW HOURS
FROM NOW. A MIX OF PRECIP TYPES IS EXPECTED AS WARMER AIR NOSES IN
ALOFT AND SURFACE TEMPS INITIALLY HOVER AROUND OR JUST BELOW
FREEZING BEFORE WARMING TOWARD MIDDAY. NORTHERN AREAS INCLUDING
ORD/RFD/DPA LOOK TO SEE PRIMARILY SNOW BUT SOME SLEET IS POSSIBLE
TOO AS WARM AIR APPROACHES ALOFT. SOUTHERN AREAS INCLUDING MDW/GYY
LOOK TO HAVE MORE OF A MIX OF RAIN AND SNOW WITH FREEZING RAIN
POSSIBLE THROUGH MID MORNING...AT LEAST AT TIMES...BEFORE SURFACE
TEMPS WARM ABOVE FREEZING. THE BULK OF THE PRECIPITATION IS
EXPECTED TO FALL PRIOR TO 18-20Z WHEN MID LEVEL MOISTURE AND
FORCING DIMINISHES...BUT SOME DRIZZLE MAY LINGER THROUGH EARLY
AFTERNOON. SOME SLUSHY ACCUMULATION IS POSSIBLE...ESPECIALLY
TOWARD RFD WHERE TEMPS WILL BE COLDEST OVERALL AND THIS WOULD
MAINLY ACCUMULATE DURING THE MORNING.
EAST-SOUTHEAST WINDS WILL CONTINUE WITH GUSTS TO AROUND 20 KT AT
TIMES THROUGH DAYBREAK BUT SPEEDS SHOULD EASE UP MID/LATE MORNING
BEFORE WINDS SHIFT TO THE SOUTHWEST THEN WEST THIS AFTERNOON. A
STRONG PUSH OF COLDER AIR WILL PUSH TEMPS BACK BELOW FREEZING LATE
IN THE DAY/THIS EVENING WITH STEEP LAPSE RATES SUPPORTING SOME
RENEWED SNOW FLURRY/SNOW SHOWER DEVELOPMENT BY EVENING WHICH MAY
CONTINUE OVERNIGHT AS WELL. WIND SPEEDS WILL ALSO PICK UP AS WINDS
SHIFT LATE IN THE DAY WITH GUSTS INCREASING TO AROUND 30 IF NOT 35
KTS FOR THE EVENING AND OVERNIGHT.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE IN TIMING/TRENDS AND TYPE OF PRECIP.
* MEDIUM CONFIDENCE IN PERIOD OF PREVAILING IFR CIG/VIS DURING
MONDAY MORNING/MIDDAY.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY THROUGH SATURDAY...MAINLY VFR. GUSTY WEST WINDS TUE.
RATZER
&&
.MARINE...
233 PM CDT
MAIN CONCERN FOR THE MARINE FORECAST WILL BE PERIOD OF GALES
POSSIBLE MONDAY EVENING THROUGH LATE TUESDAY. TODAY...HIGH PRESSURE
IS CENTERED OVER THE GREAT LAKES REGION PROVIDING DIMINISHING
EAST/NORTHEAST FLOW ACROSS LAKE MICHIGAN. TWO AREAS OF LOW PRESSURE
ARE TAKING SHAPE...ONE ACROSS THE NORTHERN ROCKIES AND THE SECOND
OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THE NORTHERN LOW
IS EXPECTED TO MOVE EAST INTO MINNESOTA TONIGHT WITH WINDS OVER THE
LAKE BECOMING SOUTHEAST AND INCREASING INTO THE 20 TO 25 KT POSSIBLY
30 KT RANGE. THE GRADIENT AHEAD OF THE LOW THEN QUICKLY DIMINISHES
MONDAY AS THE LOW MOVES INTO WISCONSIN AND BROAD TROUGHING TAKES
PLACES ACROSS LAKE MICHIGAN BETWEEN THE NORTHERN LOW...AND THE
SOUTHERN LOW AS IT MOVES INTO THE SOUTHERN APPALACHIANS. THIS SHOULD
ALLOW WINDS TO DIMINISH FOR A SHORT PERIOD DURING THE DAY MONDAY
BEFORE WINDS TURN SOUTHWEST...THEN WEST AND QUICKLY INCREASE AGAIN
AS THE NORTHERN LOW MOVES EAST OF LAKE MICHIGAN. WITH THE GRADIENT
QUICKLY STRENGTHENS AND STRONG HEIGHT RISES MOVING IN BEHIND THE
DEPARTING LOW...GALES ARE EXPECTED ACROSS PORTIONS OF LAKE MICHIGAN.
CURRENTLY...THE BEST CHANCES FOR GALES APPEAR ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE LAKE...WITH THE GRADIENT SLIGHTLY WEAKER
ACROSS FAR NORTHERN LAKE MICHIGAN CLOSER TO THE LOW TRACK. WILL
ISSUE A GALE WATCH FOR THESE AREAS MONDAY EVENING THROUGH TUESDAY
EVENING. WINDS REMAIN ELEVATED AROUND 30 KT THROUGH THE DAY
WEDNESDAY BEFORE GRADUALLY TAPERING LATE IN THE WEEK.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
GALE WATCH...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WATCH...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
554 AM EDT MON MAR 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 551 AM EDT MON MAR 18 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A VIGOROUS LOOKING
SHORTWAVE TROF MOVING ACROSS THE NRN PLAINS TOWARD THE UPPER
MISSISSIPPI VALLEY. BAND OF SNOW HAS BEEN SLOWLY ORGANIZING DURING
THE NIGHT ACROSS MN AHEAD OF FEATURE. FRONTAL BOUNDARY DRAPPED
ACROSS THE OHIO/TENNESSEE VALLEYS IS EFFECTIVELY PREVENTING A GOOD
SURGE OF MOISTURE N TO THE UPPER LAKES AHEAD OF WAVE. PER 00Z
RAOBS...PRECIPITABLE WATER VALUES UPWARDS OF 1 INCH ARE SOUTH OF
THE BOUNDARY WHILE VALUES ARE ONE-QUARTER TO ONE-HALF INCH OVER THE
NRN PLAINS...JUST A LITTLE ABOVE NORMAL FOR THIS TIME OF YEAR. THIS
WILL WORK TO KEEP SNOW ACCUMULATIONS IN CHECK DESPITE VIGOROUS
DYNAMICS ASSOCIATED WITH SHORTWAVE BECOMING INCREASINGLY NEGATIVELY
TILTED AS IT MOVES ACROSS THE WRN GREAT LAKES LATE THIS
AFTN/TONIGHT.
OVERALL...FCST FOR TODAY/TONIGHT WAS IN GOOD SHAPE...SO NO MAJOR
ADJUSTMENTS WERE MADE. SLOWED TIMING OF SNOW JUST A BIT BASED ON
OVERNIGHT RADAR TRENDS AND MODEL TRENDS. MODEL CONSENSUS PCPN
AMOUNTS ARE ROUGHLY 0.2 TO 0.4 INCHES. WITH SNOW RATIOS LIKELY
AROUND 15 TO 1...ADVY FOR GENERAL SNOWFALL OF 3 TO 6 INCHES LOOKS ON
TRACK. MOST LOCATIONS WILL PROBABLY BE IN THE 3-4 INCH RANGE...AND
THE SNOW MAY FALL AT DECENT RATE FOR A WHILE.
SNOW WILL DIMINISH TO PATCHY -SN W TO E TONIGHT AS BAND OF SNOW TIED
TO STRONG FORCING AHEAD OF SHORTWAVE DEPARTS. ATTENTION OVERNIGHT
THEN TURNS TO THE W WHERE STRONG NW WINDS WILL DEVELOP IN THE WAKE
OF SFC LOW MOVING ACROSS LAKE SUPERIOR. WHILE THERE IS SOME
UNCERTAINTY IN TIMING THE ARRIVAL OF THE STRONG NW WINDS...WHICH
WILL ARRIVE OVER GOGEBIC/ONTONAGON COUNTIES BEFORE THE
KEWEENAW...DEEP MOISTURE/CONVERGENT CYCLONIC FLOW AND A DEEP DGZ
SUGGEST VERY HVY LAKE ENHANCED SNOW WILL LIKELY DEVELOP FROM KIWD N
THRU THE KEWEENAW BY DAYBREAK. COULD EASILY SEE SNOWFALL RATES OF
1-3IN/HR INTO TUE MORNING ACROSS THE HIGHER TERRAIN OF THE W. BLSN
WILL ALSO BECOME AN INCREASING HAZARD AS NW WINDS WILL GUST OVER
30MPH TO AS HIGH AS 40MPH...ESPECIALLY IN OPEN AREAS NEAR LAKE
SUPERIOR. WHITE-OUTS WILL BE A GOOD POSSIBILITY DUE TO COMBINATION
OF HVY SNOW/BLSN.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 551 AM EDT MON MAR 18 2013
MODELS AGREE THAT STRONG SHORTWAVE MOVING THROUGH THE REGION TODAY
HELPS TO ESTABLISH LOW-MID LEVEL TROUGHING THROUGH THE WEEK. ONCE
SFC-H85 LOWS PUSH EAST OF LK SUPERIOR...EXPECT COLD AIR TO POUR
ACROSS THE ENTIRE GREAT LAKES REGION. SINCE THE TROUGH IS NEARLY
STATIONARY A LOT OF MOISTURE THROUGH H7 PERSISTS ACROSS THE REGION
THROUGH AT LEAST WEDNESDAY. ENOUGH COLD AIR IN BLYR TO SUPPORT AT
LEAST MODERATE LK EFFECT SNOWS THROUGH MIDWEEK BEFORE CONDITIONS
BECOME MORE MARGINAL BY LATE WEEK AS MOISTURE ABOVE H9 DIMINISHES
AND LOW-LEVEL FLOW BECOMES NOT AS CYCLONIC. PROLONGED PERIOD OF
MODERATE LK EFFECT SNOWS EXPECTED WITH POTENTIAL HEAVY LK EFFECT AT
TIMES THROUGH WEDNESDAY GIVEN DEEP MOISTURE IN PLACE...STRONGEST
LOW-LEVEL CONVERGENCE AND GREATEST INSTABILITY WITH DELTA T/S OVER
15C AND LAKE EQL TOWARD 10KFT. SOUNDINGS ALSO SHOW MAJORITY OF LAKE
CONVECTIVE LAYER WITHIN THE DGZ WHICH HELPS BOOST SLR/S OVER 20:1.
OTHER FACTOR TUESDAY/TUESDAY NIGHT AND INTO WEDNESDAY MORNING WILL
BE STRONG WINDS WITH OVER 30 KTS LOCATED WITHIN THE BLYR. GUSTS OVER
35KT/40 MPH SEEM POSSIBLE IN THE MOST VIGOROUS LK EFFECT CONVECTION.
BLOWING SNOW WILL INCREASE BY LATER TUESDAY AFTN IN AREAS FAVORED BY
NW WINDS AND THIS HAZARD WILL CONTINUE THROUGH MUCH OF WEDNESDAY.
A COUPLE MAIN ISSUES TO SORT OUT AND THESE ARE NOT TRIVIAL AS THEY
IMPACTED HEADLINE DECISIONS THIS MORNING. MAIN ISSUE THROUGH TUESDAY
IS THERE APPEARS TO BE A BREAK BTWN THE SYNOPTIC SNOW THAT MOVES
THROUGH THIS AFTN/TONIGHT AND INCREASING LK ENHANCED SNOW OVER EAST
ON TUESDAY AFTN. LOCAL WRF AND REGIONAL GEM AGRESSIVE IN DEVELOPING
SFC TROUGH OVER EASTERN CWA ON TUESDAY MORNING TO THE SOUTH OF
PRIMARY SFC LOW OVER EASTERN LK SUPERIOR. COARSER GFS HINTS AT THIS
IDEA AS WELL. WINDS AHEAD OF TROUGH BACK SW SO THAT LK EFFECT ISSUES
PROBABLY WILL NOT DEVELOP OVER THE FAR EAST UNTIL AFTER 18Z ON
TUESDAY. ONCE TROUGH SHIFTS THROUGH...LK EFFECT COULD BECOME QUITE
INTENSE JUST IN WAKE OF TROUGH AS CONVERGENCE RAMPS UP AND COLD AIR
ARRIVES LEADING TO QUICKLY INCREASING OVER-WATER INSTABILITY. GIVEN
CERTAIN BLSN HAZARD ALONG WITH HEAVIER LK ENHANCED SNOWFALL...A
WARNING MAY EVENTUALLY BE NEEDED. SINCE THERE WILL BE ENOUGH OF A
GAP BTWN THE SYNOPTIC SNOW AND HEAVIER LK ENHANCED SNOW LATER
TUESDAY DECIDED IN FAVOR OF WINTER STORM WATCH FOR EASTERN CWA NEAR
LK SUPERIOR 12Z TUESDAY THROUGH 12Z THURSDAY. DID NOT GET TOO
SPECIFIC WITH TIMING SINCE SOME MODELS DO SHOW QUICKER ONSET OF LK
ENHANCED SNOW THAN GEM-REGIONAL AND LOCAL-WRF...ESPECIALLY IN THE
MUNISING AND GRAND MARAIS AREAS. WESTERN TIER OF CWA IS MORE CLEAR
CUT. MAIN ISSUE OVER THE WEST IS HOW LONG TO RUN THE WARNING. KEPT
IT PRETTY SIMPLE AT THIS POINT AND KEPT WARNING IN PLACE UNTIL WINDS
IN BLYR BEGIN TO DECREASE BLO 25 KTS AND WHEN DEEPER MOISTURE STARTS
TO CUT OUT. ON BOTH ACCOUNTS IT APPEARS SUITABLE CUTOFF WAS DAYBREAK
ON THURSDAY MORNING. MORE LK EFFECT CONTINUES ON THURSDAY...BUT
SHOULD BE BEGINNING TO SHOW DIMINISHING TREND COMPARED TO MORE
FAVORABLE SETUP IN PLACE TUESDAY AND WEDNESDAY.
LK EFFECT DIMINISHES FURTHER INTO FRIDAY BUT PROBABLY WILL NOT GO
AWAY COMPLETELY AS LIGHT WIND PERSISTS OFF LK SUPERIOR. THOUGH H85
TEMPS ARE WARMING...COOL ENOUGH BENEATH LOWERING INVERSION TO HAVE
SOME LGT SNOW SHOWERS/FLURRIES. NO SIGNIFICANT WX INTO THE WEEKEND
BUT NOT ALL THAT WARM EITHER AS GENERAL TROUGHING CONTINUES. SINCE
MOST OF FOCUS WAS ON SNOW/BLSN AND HEADLINES...USED MODEL CONSENSUS
FOR THE FORECAST BEYOND THURSDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 112 AM EDT MON MAR 18 2013
WITH SFC HIGH PRES IN CONTROL...DRY LOW-LEVELS WILL MAINTAIN VFR
CONDITIONS OVERNIGHT. A TIGHTENING PRES GRADIENT AND NOCTURNAL
INVERSION WILL LEAD TO LLWS OVER THE WEST AT IWD. INCREASING MOISTURE
AHEAD OF AN APPROACHING FRONTAL SYSTEM ALONG WITH UPSLOPE SE FLOW
BRINGING MOISTURE FROM LAKE MICHIGAN MAY BRING MVFR CIGS INTO SAW
DURING THE MORNING BUT CONFIDENCE IS ONLY MODERATE. THE ONSET OF
LIGHT SNOW SHOULD BRING BOTH MVFR CIGS/VSBY INTO IWD BY EARLY AFTN
AND INTO KCMX/SAW BY MID TO LATE AFTN. AS THE SNOW INTENSITY
INCREASES...EXPECT MAINLY IFR CONDITIONS BY EVENING. WITH THE PASSAGE
OF A TROUGH AXIS DURING THE EVENING...WINDS WILL VEER FROM SE TO W.
CONDITIONS MAY BRIEFLY IMPROVE OVER THE WEST BEFORE LAKE ENHANCED
SNOW INCREASES.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 551 AM EDT MON MAR 18 2013
AS LOW PRES OVER THE EASTERN DAKOTAS MOVES E...TIGHT PRES GRADIENT
AHEAD OF THE LOW WILL BRING SE WINDS UP TO 30KT TODAY. GALES WILL
LIKELY OCCUR TOWARD MID LAKE PORTIONS OF NCNTRL AND ERN LAKE
SUPERIOR...IN PARTICULAR FROM AROUND WHITEFISH PT NW TOWARD PASSAGE
ISLAND. AFTER THE LOW EXITS TO THE E...NORTHWEST GALES WILL DEVELOP
FROM W TO E LATE TONIGHT/TUE. THE GALES WILL THEN CONTINUE INTO WED
OVER THE E HALF OF THE LAKE. WINDS WILL SLOWLY DIMINISH TO UNDER 25KT
FROM W TO E WED NIGHT/THU. THE COMBINATION OF COLD AIR/STRONG
WINDS/HIGH WAVES WILL LEAD TO PERIODS OF HVY FREEZING SPRAY TUE THRU
WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING FROM 2 PM THIS AFTERNOON TO 8 PM EDT
WEDNESDAY FOR MIZ001-003-004-084.
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 5 AM EDT
TUESDAY FOR MIZ006-007-014-085.
WINTER STORM WATCH FROM TUESDAY MORNING THROUGH THURSDAY MORNING
FOR MIZ006-007-085.
WINTER STORM WARNING FROM 10 AM EDT /9 AM CDT/ THIS MORNING TO 8
PM EDT /7 PM CDT/ WEDNESDAY FOR MIZ002-009.
WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 2 AM EDT
TUESDAY FOR MIZ005-013.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 1 AM CDT TUESDAY FOR
MIZ010>012.
LAKE SUPERIOR...
GALE WARNING UNTIL 2 PM EDT WEDNESDAY FOR LSZ264-266-267.
GALE WARNING FROM 2 PM TUESDAY TO 2 PM EDT WEDNESDAY FOR
LSZ243>251-265.
GALE WARNING FROM 8 AM EDT /7 AM CDT/ TUESDAY TO 2 PM EDT /1 PM
CDT/ WEDNESDAY FOR LSZ162-240>242-263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...JLB
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
348 AM CDT MON MAR 18 2013
.SHORT TERM (TODAY-TONIGHT)...
EXTENT OF BLIZZARD CONDITIONS WILL BE THE MAIN CHALLENGE. THE
STORM IS UNFOLDING PRETTY MUCH AS PLANNED WITH THE SURFACE LOW
JUST SOUTHWEST OF FARGO AS OF 08Z.
WARM AIR ADVECTION SNOWFALL AHEAD OF THIS SYSTEM WILL LIKELY HAVE
DROPPED 3 TO 6 INCHES OF SNOW ACROSS MOST AREAS BY SUNRISE.
ANOTHER 2-4 INCHES ARE EXPECTED ACROSS THE NE FA WITHIN THE MID-
LEVEL DEFORMATION ZONE...AND ANOTHER INCH OR TWO ELSEWHERE. TOTAL
SNOWFALL OF 6 TO 10 INCHES ACROSS THE NE FA...AND 4 TO 8 INCHES
ELSEWHERE IS STILL REASONABLE.
THE 00Z GEM AND ECMWF ARE SLIGHTLY SOUTH OF THE 00Z GFS AND NAM
WITH THE TRACK OF THE SURFACE LOW. THE 07Z RAP IS CLOSE TO THE
GFS/NAM TRACK...WHILE THE 06Z NAM HAS TRENDED SLIGHTLY SOUTH. THE
DISCREPANCY IS NOT HUGE...BUT COULD MEAN THE DIFFERENCE BETWEEN
WINTER STORM OR BLIZZARD CONDITIONS ACROSS THE NORTHERN RED RIVER
VALLEY. AS THIS SYSTEM PROPAGATES TO THE EAST/NORTHEAST...STRONG
LOW-LEVEL COLD AIR ADVECTION AND 40 KNOT 925MB WINDS WILL MOVE
INTO THE SOUTHERN FA...BASICALLY WHERE THE CURRENT BLIZZARD
WARNING IS ALREADY IN EFFECT...SO THIS IS GOOD. THE MAIN CHALLENGE
WILL BE LATER THIS MORNING INTO THE AFTERNOON HOURS. THE NORTHERN
SOLUTION...SUCH AS THE 07Z RAP BRINGS AN AREA OF LOW-LEVEL COLD
AIR ADVECTION ACROSS THE NORTHERN FA AROUND 18Z...AND INCREASES
925MB WINDS TO AROUND 40 KNOTS. THE SOUTHERN SOLUTION IS WEAKER
WITH THE COLD AIR ADVECTION...WITH 925MB WINDS AROUND 35 KNOTS.
THIS WILL LIKELY BE THE DIFFERENCE BETWEEN WINTER STORM AND
BLIZZARD CONDITIONS. 08Z SURFACE ANALYSIS WOULD ARGUE FOR THE
SOUTHERN SOLUTION GIVEN STRONGEST PRESSURE FALLS INTO THE BEMIDJI
AREA. FOR THIS REASON WILL MAKE NO CHANGES TO THE HEADLINES...BUT
WILL MONITOR INCOMING OBSERVATIONS AND MODEL GUIDANCE AS AN
UPGRADE TO A BLIZZARD WARNING ACROSS THE NORTHERN RED RIVER VALLEY
IS NOT OUT OF THE QUESTION.
.LONG TERM (TUESDAY-SUNDAY NIGHT)...
AFTER THE LAST OF THE CURRENT WINTER STORM MOVES OUT OF THE REGION
LATER TONIGHT...TUESDAY TROUGH THE WORK WEEK AND INTO NEXT WEEKEND
WILL BE QUIET WEATHER-WISE. NORTHWEST FLOW ALOFT ON TUESDAY WILL
BECOME WEAK AND ILL-DEFINED BY THURSDAY AS INTERMOUNTAIN RIDGE
WEAKENS AND MOVES INTO THE CENTRAL PLAINS. AT THE SURFACE...HIGH
PRESSURE WILL DOMINATE THE NORTHERN PLAINS FOR MUCH OF THE WEEK.
BEST CHANCE FOR PERSISTENT CLOUD COVER WILL BE ACROSS NORTHWEST MN
WITH MORE SUN THAN CLOUDS ALONG AND WEST OF THE VALLEY. THERE IS A
SLIGHT CHANCE FOR SNOW SHOWERS FRIDAY AND FRIDAY NIGHT ACROSS THE
WEST IN RESPONSE TO MID-LEVEL WARM ADVECTION. OTHERWISE...EXPECT DRY
CONDITIONS. TEMPERATURES WILL REMAIN WELL BELOW MID-MARCH NORMALS
THROUGH THURSDAY...THEN SLOWLY INCREASING EACH DAY FRIDAY INTO THE
WEEKEND WITH THE APPROACHING RIDGE. CURRENT FORECAST SHOWS DAYTIME
HIGHS APPROACHING THE FREEZING MARK SATURDAY INTO SUNDAY.
&&
.AVIATION...
MVFR/IFR CEILINGS TO PERSIST MOST OF THE DAY AS LIGHT TO MODERATE
SNOW SLOWLY MOVES FROM WEST TO EAST. GUSTY SOUTHEAST WIND WILL
ABRUPTLY SHIFT TO THE NORTHWEST AS SURFACE LOW CURRENTLY NEAR KFAR
EJECTS TO THE NORTH AND EAST THROUGH THE MORNING. GUSTS TO 35 KTS
ARE POSSIBLE IN NORTHWEST FLOW...CREATING CONSIDERABLE BLOWING/
DRIFTING SNOW AND VISIBILITIES DOWN TO ONE HALF MILE OR LESS AT ALL
TAF SITES. MULTIPLE AMENDMENTS ARE POSSIBLE...BUT CONDITIONS SHOULD
VERY SLOWLY IMPROVE THIS EVENING AND OVERNIGHT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...BLIZZARD WARNING UNTIL 7 PM CDT THIS EVENING FOR NDZ028-038-039-
049-052-053.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR NDZ006>008-
014>016-024-026-027-029-030-054.
MN...BLIZZARD WARNING UNTIL 7 PM CDT THIS EVENING FOR MNZ003-029-030-
040.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR MNZ001-002-
004>009-013>017-022>024-027-028-031-032.
&&
$$
TG/ROGERS
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1236 AM CDT MON MAR 18 2013
.UPDATE...
ISSUED AT 1005 PM CDT SUN MAR 17 2013
ADJUSTED POPS THIS EVENING AND OVERNIGHT TO ACCOUNT FOR FASTER
MOVEMENT EAST OF MAIN PRE-FRONTAL PRECIPITATION BAND...AND ALSO TO
ADD IN SOME AREAS OF ISOLATED-SCATTERED SNOW SHOWERS ACROSS THE
SOUTHWEST PARTS OF THE CWA LATER TONIGHT AS THE MOISTURE CONTINUES TO
WRAP AROUND THE SOUTH SIDE OF THE LOW. WITH THE FASTER MOVEMENT...
ALSO DECREASED SOME SNOWFALL AMOUNTS FOR THE OVERNIGHT...THOUGH STILL
LOOKING AT AREAS OF 1-2 INCHES THROUGH THE ADVISORY AREA. GIVEN THE
POTENTIAL FOR ADDITIONAL SNOW SHOWERS WITH THE VERY STRONG WINDS ON
MONDAY...OPTED TO LEAVE GOING HEADLINES AS IS FOR NOW...BUT MIDNIGHT
SHIFT WILL LIKELY HAVE TO REEVALUATE AFTER GETTING A BETTER LOOK AT
THIS SNOW SHOWER POTENTIAL ON INCOMING MODEL RUNS.
UPDATE ISSUED AT 825 PM CDT SUN MAR 17 2013
COMPLEX SITUATION TONIGHT...WITH A NARROW BAND OF PRE-FRONTAL
PRECIPITATION MOVING SLOWLY EAST ACROSS SOUTHEAST SD EARLY THIS
EVENING. WEB CAMS INDICATE SOME SLUSHY ACCUMULATIONS WITHIN THE
HEAVIER AREAS OF PRECIPITATION NORTH OF I-90 WHERE SURFACE TEMPS ARE
BELOW FREEZING...WHILE AREAS SOUTH ARE SEEING LITTLE ACCUMULATION AS
OF YET. OVERALL NOT MUCH CHANGE TO GOING FORECAST...THOUGH DID SLOW
UP EASTWARD PROGRESSION OF THE SNOW BAND A BIT...WHICH ALSO RESULTED
IN DELAYING START OF ADVISORY EAST OF HIGHWAY 60 UNTIL MIDNIGHT.
WITH THE HEAVIER BAND IN EAST CENTRAL SD THIS EVENING HAVE BUMPED UP
SNOW AMOUNTS THERE SLIGHTLY...WHILE NOTCHING DOWN A LITTLE IN OUR
SOUTHEAST AREAS WHERE LITTLE SNOW IS EXPECTED THIS EVENING. STILL
GENERALLY LOOKING AT 1-3 INCHES ACROSS THE EXISTING WINTER WEATHER
ADVISORY AREA THOUGH...SO NO CHANGES TO AREA COVERED BY HEADLINES AT
THIS TIME. UPDATED GRIDS/PFM HAVE BEEN SENT...AND WILL GET A NEW ZFP
OUT SHORTLY.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 351 PM CDT SUN MAR 17 2013
STRONG FORCING PUSHING OUT INTO THE SOUTHWESTERN PORTIONS OF THE
RUSHMORE STATE AND NEBRASKA PANHANDLE. VERY STEEP LAPSE RATES IN
PLACE EVIDENCED BY A FEW LIGHTNING STRIKES ACROSS WESTERN AND NORTH
CENTRAL NEBRASKA DURING THE EARLY AND MID AFTERNOON. AHEAD OF THIS
WAVE AND DEVELOPING LOW PRESSURE...STRONG SOUTHERLY WINDS IN
PLACE...WITH ADVISORY LEVEL WINDS AT TIMES AROUND THE LOWER BRULE
AREA. THESE WINDS SHOULD EASE A BIT GOING INTO THE EARLY EVENING...
WHILE THE MAIN GRADIENT LIFTS NORTH AND EAST WITH THE MAIN CYCLONE
CENTER HEADING TOWARD EXTREME NORTHEAST SOUTH DAKOTA BY LATE EVENING.
SEVERAL BANDS OF SHOWERS IN PROCESS OF DEVELOPING ACROSS THE STATE.
HI RES MODELS...INCLUDING RAP AND SREF...HAVE TRENDED QUICKER WITH
THE PRECIP...WITH MUCH OF THE BAND EAST OF I29 BY 07-08Z...WITH
EXCEPTION OF AREA ACROSS NORTHERN CWA CLOSER TO THE MID LEVEL
CIRCULATION. NATURE OF A VERY TRANSIENT BAND WILL BE LIMITING FACTOR
ON AMOUNTS...AS WILL THE TEMPERATURES ALOFT WHICH FIGURE UP JUST A
BIT TOO WARM FOR ANY SNOW IN THE FAR SOUTHWEST...AND WILL KEEP A MIX
IN THE WORKS FROM JAMES THROUGH LOWER MISSOURI VALLEY. ONLY THE
COOLER AND SLIGHTLY DRIER AIRMASS TO THE EAST...ALONG WITH THE
DYNAMIC COOLING RESULTING FROM CONVECTIVE NATURE TO PRECIPITATION
AND SHARP LIFT FORCING WILL FORCE PRECIPITATION OVER TO SNOWFALL.
AMOUNTS SOMEWHAT DIFFICULT TO PIN DOWN GIVEN THE CONVECTIVE
NATURE...WITH AMOUNTS EXPECTED TO REFLECT THE AREAL AVERAGE...
GREATEST ACROSS PARTS OF NORTHWEST IOWA INTO SOUTHWEST MINNESOTA.
DEBATE FOR THE DAY WAS WHAT IT MIGHT TAKE TO GET BLIZZARD CONDITIONS
GIVEN THE CERTAINTY OF STRONG WINDS ON LATE SUNDAY NIGHT AND THROUGH
THE DAY MONDAY. CERTAINLY NONE OF THE REMAINING SNOW COVER WILL
CONTRIBUTE DIRECTLY...AND REALLY ONLY HAVE AROUND A TWO INCH BAND
ACROSS THE NORTHERN TIER ALONG HIGHWAY 14. STRONGEST WINDS WITH
GUSTS UPWARD OF 45 MPH AT TIMES WILL BE FROM EAST CENTRAL SOUTH
DAKOTA THROUGH SOUTHWEST MINNESOTA...SPEEDS TAPERING OFF SLIGHTLY TO
THE SOUTHWEST...BUT BALANCED SOMEWHAT BY A DEEPER MIXING PROFILE.
NOT EXPECTING A GREAT DEAL OF ADDITIONAL SNOW BY MONDAY...WITH ONLY
THE STEEP LOW LEVEL LAPSE RATES IN REACH OF FAVORABLE ICE GROWTH
RANGE SUGGESTING BANDED SHALLOW SNOW SQUALLS... SO CONTRIBUTIONS
HERE WILL BE FAIRLY MINIMAL. WHERE WE GET A COUPLE OF INCHES OVER
EXISTING SNOW/ICE COVER...WILL BE VERY CAPABLE OF SOME DECENT
LOFTING. WHERE NO SNOW COVER CURRENTLY EXISTS...WILL BE MUCH MORE
DIFFICULT TO OBTAIN ANY TRUE BLIZZARD CONDITIONS...BUT DID ADD IN A
COUPLE MORE COUNTIES TOWARD THE SOUTH IN SOUTHWEST MINNESOTA TOWARD
WHERE SOME HEAVIER SNOWFALL MAY OCCUR. FARTHER SOUTH AND WEST...
NOT EXPECTING ANY WHITEOUT CONDITIONS TO BE WIDESPREAD...BUT THAT IS
NOT SAYING THERE WOULD BE ANY WHITEOUT CONDITIONS...JUST NOT
WIDESPREAD OR LONG LASTING. CAUTION IS NEEDED...EVEN THROUGH THE
ADVISORY AREA. DID NOT POST BLIZZARD WARNING RIGHT OFF TO START...
AS STRONGER WINDS WILL COME IN LATER TONIGHT/EARLY MONDAY IN THE
WARNING AREA...SO PRECEDED WITH A WINTER WEATHER ADVISORY UP TO 09Z
IN THE BLIZZARD AREA FOR THE COMBINATION OF SNOWFALL AND SOME LESSER
POTENTIAL BLOWING SNOW WITH THE PRE-FRONTAL SOUTH/SOUTHWEST WINDS.
PROBABLY NOT A GREAT DEAL OF ROOM FOR RECOVERY IN TEMPS ON MONDAY
WITH STRONG SURGE OF COLDER AIR WRAPPING IN BEHIND SYSTEM. ONLY THE
MORE MIXED MISSOURI VALLEY WHERE LESS SNOW IS EXPECTED SHOULD SEE
ANY LESS THAN MINIMAL RECOVERY IN TEMPS.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 351 PM CDT SUN MAR 17 2013
THE SYSTEM PULLS OUT OF THE REGION ON MONDAY NIGHT...WITH GUSTY
NORTHWESTERLY WINDS DYING THROUGH THE EVENING AS A SURFACE RIDGE
SLIDES SOUTHWARD INTO THE NORTHERN PLAINS CAUSING THE GRADIENT TO
SLACKEN. TEMPERATURES ARE TRICKY THAT NIGHT...DEPENDENT ON HOW
QUICKLY THE WINDS DIE/WHERE NEW FALLEN SNOW IS IN PLACE/AND HOW MUCH
CLEARING IS REALIZED OVERNIGHT. MODEL RH TIME SECTIONS POINT TOWARD
LOWER CLOUDS CLEARING FROM WEST TO EAST DURING THE EVENING...THOUGH
MID/HIGH CLOUDS INCREASING IN THE WEST LATER AT NIGHT. AT THIS
POINT...WENT WITH LOWS AROUND ZERO ALONG HIGHWAY 14 TO THE LOWER
TEENS THROUGH THE MISSOURI RIVER CORRIDOR.
ANOTHER WEAK SHORTWAVE WILL TRACK ACROSS THE AREA ON TUESDAY...AND
MAY BE JUST ENOUGH MOISTURE AROUND TO KICK OFF A FEW FLURRIES IN OUR
EAST. TEMPERATURES WILL STILL BE MUCH BELOW NORMAL FOR THIS TIME OF
YEAR WITH HIGHS GENERALLY IN THE 20S NORTH TO 30S SOUTH. FARTHER
INTO THE EXTENDED...A BROAD UPPER LEVEL LOW OVER THE EASTERN
PORTIONS OF THE COUNTRY WILL KEEP OUR AREA IN A NORTHWESTERLY UPPER
LEVEL FLOW FOR WEDNESDAY AND EARLY THURSDAY BEFORE THE NEXT
SHORTWAVE BEGINS TO ENCROACH ON THE AREA IN THE LATE THURSDAY TO
FRIDAY TIME FRAME. MODELS CONTINUE TO DIFFER ON HOW THEY HANDLE THIS
SYSTEM...WITH BOTH THE ECMWF AND GEM KEEPING IT FARTHER TO THE
SOUTH..AND THE GFS PERSISTING WITH A MORE NORTHERLY SOLUTION. SOME
CONSENSUS...WEIGHED MORE HEAVILY TO THE MORE SOUTHERLY SOLUTION
WOULD BRING A CHANCE OF LIGHT SNOW TO OUR SOUTHWEST DURING THIS TIME
FRAME. MODELS KEEP MUCH BELOW NORMAL THERMAL PROFILES IN PLACE
ACROSS THE REGION THROUGH NEXT WEEKEND...WITH HIGHS GENERALLY 20S AND
30S...AND LOWS SINGLE DIGITS AND TEENS EARLY ON...TO TEENS AND 20S
LATE IN THE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1228 AM CDT MON MAR 18 2013
SHORT TERM ISSUES INCLUDE A NORTH TO SOUTH ORIENTATED BAND OF
PRECIPITATION MOVING EASTWARD ACROSS SOUTHWEST MN AND NORTHWEST
IA. AT THIS POINT...THE PRECIPITATION IS MAINLY A SLEET AND SNOW
MIX...AND WILL EXIT THE FORECAST AREA BETWEEN NOW AND 08Z MONDAY.
THERE WILL BE AREAS OF IFR CEILINGS ALONG AND EAST OF I 29 THROUGH
ABOUT 10Z MONDAY...THEN REPLACED BY PRIMARILY MVFR CONDITIONS. AS
MONDAY PROGRESSES...THE FORECAST AREA WILL LIKELY EXPERIENCE
STRONG MIXING WHICH WILL ELEVATE THE CUMULUS LEVEL TO LOW END VFR
OR UPPER END MVFR. THE BEST CHANCES FOR WRAP AROUND SNOW SHOWERS
ON MONDAY WHICH WOULD GREATLY REDUCE VISIBILITIES AT TIMES INTO
THE LIFR TO IFR RANGE...WILL BE ALONG AND EAST OF A BROOKINGS SD
TO LUVERNE MN LINE. AT THIS TIME...DECIDED TO TAKE THE OPTIMISTIC
ROUTE CONCERNING SNOW SHOWER ACTIVITY ON MONDAY FOR THE
KHON...KFSD AND KSUX TAF SITES...THINKING THAT THE ACTIVITY WILL
STAY MOSTLY TO THE EAST OF THESE LOCATIONS. AND FINALLY...WINDS
WILL SHIFT TO THE NORTHWEST AND WEST/NORTHWEST BETWEEN NOW AND 12Z
MONDAY. THEY WILL BE QUITE STRONG...WITH SUSTAINED WINDS
FREQUENTLY AT LEAST 25 KNOTS AND GUSTINESS OF 35 TO 40 KNOTS
THROUGH 21Z TO 22Z MONDAY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR SDZ038-
054>056-062-067.
WIND ADVISORY FROM 4 AM EARLY THIS MORNING TO 7 PM CDT THIS
EVENING FOR SDZ050-052-053-057>061-063>066-068>071.
WINTER WEATHER ADVISORY UNTIL 4 AM CDT EARLY THIS MORNING FOR
SDZ039-040.
BLIZZARD WARNING FROM 4 AM EARLY THIS MORNING TO 7 PM CDT THIS
EVENING FOR SDZ039-040.
MN...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MNZ089-
090-097-098.
WINTER WEATHER ADVISORY UNTIL 4 AM CDT EARLY THIS MORNING FOR
MNZ071-072-080-081.
BLIZZARD WARNING FROM 4 AM EARLY THIS MORNING TO 7 PM CDT THIS
EVENING FOR MNZ071-072-080-081.
IA...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR
IAZ001>003-012>014-020>022-032.
WIND ADVISORY FROM 4 AM EARLY THIS MORNING TO 7 PM CDT THIS
EVENING FOR IAZ031.
NE...WIND ADVISORY FROM 4 AM EARLY THIS MORNING TO 7 PM CDT THIS
EVENING FOR NEZ013-014.
&&
$$
UPDATE...JH
SHORT TERM...CHAPMAN
LONG TERM...JM
AVIATION...MJF
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
307 AM CDT MON MAR 18 2013
.MESOSCALE UPDATE...
BULK OF CONVECTION STILL DOWN ALONG THE MISSISSIPPI RIVER AND IN
FAR WESTERN KENTUCKY AT 08Z. EXPECT LEADING LINE OF SHOWERS AND
ISOLATED THUNDERSTORMS CURRENTLY FROM PARIS TO NEAR JACKSON TO
CONTINUE EASTWARD AND INTO NORTHWEST MIDDLE TENNESSEE WITH
RENEGADE ISOLATED SHOWERS/STORM OUT AHEAD OF THIS FEATURE. LOOKING
OVER SHORT RANGE GUIDANCE THINK STORMS WILL REMAIN BELOW SEVERE
LIMITS IN MIDDLE TENNESSEE THROUGH 12Z BUT FROM 15Z THROUGH THE
AFTERNOON CONVECTION DOES INTENSIFY SOUTH AND EAST OF NASHVILLE.
BOYD
&&
.PREV DISCUSSION... /ISSUED 108 AM CDT MON MAR 18 2013/
MESOSCALE UPDATE...
WARM FRONT DRAPED FROM WEST TO EAST ACROSS WEST AND MIDDLE
TENNESSEE AT 1 AM CDT. FRONT PROGGED TO LIFT NORTHWARD IN THE
OVERNIGHT HOURS PLACING MID STATE IN WARM SECTOR FOR SEVERAL
HOURS.
SREF SHOWING BROAD UPPER TROUGH DOWN THROUGH THE SOUTHERN PLAINS
WITH AXIS THROUGH OKLAHOMA INTO NORTH TEXAS AT 06Z. CONVECTION
OVER ARKANSAS HAS BEEN SLOW TO FIRE BUT RUC NOW SHOWING RATHER
STRONG UPPER DIFFLUENCE THAT AREA AND WITH APPROACHING UPPER
TROUGH AXIS THINK IT IS JUST A MATTER OF TIME. ACTIVITY SHOULD
SHIFT NORTHEAST AND INTO WESTERN TENNESSEE BETWEEN 06Z AND 09Z AND
INTO WESTERN MIDDLE TENNESSEE AFTER 09Z.
BOYD
PREV DISCUSSION... /ISSUED 833 PM CDT SUN MAR 17 2013/
UPDATE...STATIONARY FRONT WAS STILL STRETCHED ACROSS SOUTHERN AND
EASTERN MIDDLE TENNESSEE THIS EVENING...LOCATED NEAR COLUMBIA AND
CROSSVILLE. STILL LOOKS LIKE FRONT WILL LIFT BACK TO THE NORTH AS
THE NIGHT ROLLS ON AND BE NORTH OF THE KY-TN LINE BY 12Z. RAIN
CHANCES WILL INCREASE CONSIDERABLY OVER WESTERN SECTIONS BY THE
09Z-12Z PERIOD, IN WARM/MOIST TONGUE AHEAD OF APPROACHING COLD
FRONT.
COOL AIR POOLED NORTH OF STATIONARY FRONT PRODUCING TEMPS COOLER
THAN REFLECTED IN EARLIER MIN TEMP FORECAST FOR TONIGHT. THUS,
WILL UPDATE PRODUCTS TO REFLECT THIS. NEVERTHELESS, STILL EXPECT
TEMPS TO WARM FROM THE SOUTH LATER TONIGHT AS WARM FRONT LIFTS
NORTH.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
108 AM CDT MON MAR 18 2013
.MESOSCALE UPDATE...
WARM FRONT DRAPED FROM WEST TO EAST ACROSS WEST AND MIDDLE
TENNESSEE AT 1 AM CDT. FRONT PROGGED TO LIFT NORTHWARD IN THE
OVERNIGHT HOURS PLACING MID STATE IN WARM SECTOR FOR SEVERAL
HOURS.
SREF SHOWING BROAD UPPER TROUGH DOWN THROUGH THE SOUTHERN PLAINS
WITH AXIS THROUGH OKLAHOMA INTO NORTH TEXAS AT 06Z. CONVECTION
OVER ARKANSAS HAS BEEN SLOW TO FIRE BUT RUC NOW SHOWING RATHER
STRONG UPPER DIFFLUENCE THAT AREA AND WITH APPROACHING UPPER
TROUGH AXIS THINK IT IS JUST A MATTER OF TIME. ACTIVITY SHOULD
SHIFT NORTHEAST AND INTO WESTERN TENNESSEE BETWEEN 06Z AND 09Z AND
INTO WESTERN MIDDLE TENNESSEE AFTER 09Z.
BOYD
&&
.PREV DISCUSSION... /ISSUED 833 PM CDT SUN MAR 17 2013/
UPDATE...STATIONARY FRONT WAS STILL STRETCHED ACROSS SOUTHERN AND
EASTERN MIDDLE TENNESSEE THIS EVENING...LOCATED NEAR COLUMBIA AND
CROSSVILLE. STILL LOOKS LIKE FRONT WILL LIFT BACK TO THE NORTH AS
THE NIGHT ROLLS ON AND BE NORTH OF THE KY-TN LINE BY 12Z. RAIN
CHANCES WILL INCREASE CONSIDERABLY OVER WESTERN SECTIONS BY THE
09Z-12Z PERIOD, IN WARM/MOIST TONGUE AHEAD OF APPROACHING COLD
FRONT.
COOL AIR POOLED NORTH OF STATIONARY FRONT PRODUCING TEMPS COOLER
THAN REFLECTED IN EARLIER MIN TEMP FORECAST FOR TONIGHT. THUS,
WILL UPDATE PRODUCTS TO REFLECT THIS. NEVERTHELESS, STILL EXPECT
TEMPS TO WARM FROM THE SOUTH LATER TONIGHT AS WARM FRONT LIFTS
NORTH.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
149 AM EDT MON MAR 18 2013
.SYNOPSIS...
COLD AIR DAMMING WAS IN CONTROL OF THE AREA WITH A STATIONARY
FRONT TO THE SOUTH...AND WILL REMAIN IN PLACE THROUGH MOST OF THE
DAY MONDAY...UNTIL A COLD FRONT APPROACHES FROM THE WEST LATE IN
THE DAY. THE FRONT WILL TRY TO PUSH BACK EAST...BUT THE WARM AIR
WILL LIKELY ONLY WORK ITS WAY BACK INTO FAR SOUTHWEST VIRGINIA AND
PARTS OF SOUTHEAST WEST VIRGINIA BY LATE MONDAY. WINDY CONDITIONS
SPREAD INTO THE REGION BEHIND THE COLD FRONT TUESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 1050 PM EDT SUNDAY...
TRANSITION ZONE BETWEEN RAIN AND SNOW COVERS WAS ACROSS VIRGINIA
THIS EVENING AS SHOWN BY THE 00Z SOUNDINGS. RNK HAD A WARM NOSE OF
+4 DEG C AROUND 800 MB WITH A LAYER NEARLY 5000 FEET DEEP ABOVE
FREEZING AND JUST A SMALL LAYER BELOW ZERO. IAD`S SOUNDING WAS
ALL BELOW FREEZING FROM JUST ABOVE THE SURFACE. RAP FORECAST
TEMPERATURE PROFILES WERE CLOSEST TO WHAT WAS OBSERVED AT
00Z...ALONG SURFACE TEMPERATURES THAT WERE MORE REASONABLE IN THE
WEDGE. USING THE COOLER SURFACE TEMPERATURES AND WARMER
TEMPERATURES ALOFT...ADDED MORE POCKETS OF FREEZING RAIN IN ALONG
THE BLUE RIDGE AND IN GREENBRIER COUNTY. EVEN WITH THE CHANGES IN
PRECIPITATION TYPE...LITTLE ADJUSTMENT WAS NEEDED TO OVERALL SNOW
AND SLEET ACCUMULATION. NO CHANGES FOR THE WINTER WEATHER ADVISORY
AT THIS TIME. MOST OF THE QPF COMES IN BEFORE 06Z/2AM.
AS OF 410 PM EDT SUNDAY...
WENT COLDER THAN GUIDANCE FOR HIGHS ON MONDAY...WHICH WILL HAPPEN
VERY LATE IN THE DAY MOST PLACES. WITH WEDGE LIKELY ONLY BREAKING
IN FAR SW AND WESTERN RIDGES...AND POSSIBLE ALSO IN NC PIEDMONT
AND PARTS OF SOUTHSIDE VA...MANY LOCATIONS WILL SEE NEARLY STEADY
TEMPS MONDAY. SHOWERS WILL BE MOVING IN FROM THE WEST LATE IN THE
DAY...WHICH WILL PROVIDE MIXING TO HELP BREAK BREAK THE
WEDGE...AND DECIDED THAT TIMING OF ANY CONVECTIVE POTENTIAL LOOKS
LATE ENOUGH TO NOT MENTION UNTIL EVENING TIME FRAME. THE TRICKY
PART OF MONDAY`S FORECAST IS PERHAPS FASTER TIMING OF ARRIVAL OF
SHOWERS IN THE WEST...AND FASTER BREAKING WEDGE FOR PERHAPS MUCH
WARMER TEMPERATURES AROUND THE SOUTHERN PERIPHERY.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 400 PM EDT SUNDAY...
SURFACE FRONT PROGGED TO BE ON OUR DOORSTEP 8PM MONDAY. THIS FRONT
WILL SWEEP ACROSS THE AREA FROM WEST TO EAST DURING THE OVERNIGHT.
ANTICIPATING NEAR CATEGORICAL THREAT FOR RAIN JUST PRIOR TOO THE
FRONTAL PASSAGE WITH RAPID DECREASE IN PRECIP THREAT AFTER FROPA.
MODELS SUGGEST A QUARTER TO ABOUT A HALF INCH OF RAIN TO BE
ASSOCIATED WITH THE FRONTAL PASSAGE...TEMPERATURES WARM ENOUGH
THAT IT SHOULD BE ALL LIQUID...EXCEPT FOR SOME OF THE HIGHEST
ELEVATIONS WHERE PRECIP MAY CHANGE OVER TO BRIEF PERIOD OF SNOW B4
ENDING.
BY DAYBREAK TUESDAY...FRONT WILL BE EAST OF THE FORECAST AREA WITH
DOWNSLOPE WESTERLIES RESULTING IN CLEARING SKIES ALONG AND EAST OF
THE BLUE RIDGE. LINGERING LOW LEVEL MOISTURE IN THE MTNS MAY
RESULT IN A FLURRY OR TWO THERE.
THE UPPER AIR PATTERN DOES NOT CHANGE MUCH THROUGH MID WEEK WITH
RIDGE IN THE WESTERN CONUS AND TROF IN THE EAST. THIS SUPPORTS
COLDER THAN NORMAL TEMPERATURES ACROSS OUR AREA. NORTHWEST FLOW
TUESDAY WILL PERSIST RIGHT ON INTO WEDNESDAY WITH 85H TEMPS BLOW
FREEZING. FOR THE MOST PART...THE FLOW IS DRY. THERE IS AN UPPER
LEVEL DISTURBANCE WHICH IS PROGGED TO COME THROUGH DURING THE DAY
WEDNESDAY. THIS FEATURE MAY BRING SNOW SHOWERS AND FLURRIES...BUT
MORE IMPORTANTLY A REINFORCING SHOT OF COLD AIR THAT WILL SEND
TEMPERATURES WELL BELOW NORMAL WEDNESDAY NIGHT INTO THURSDAY AS
85H TEMPERATURES TEST M14 DEG C.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 400 PM EDT SUNDAY...
A BLOCKY HEMISPHERIC CIRCULATION IS ADVERTISED BY THE LONG RANGE
MODELS THROUGH NEXT WEEKEND...MARKED BY THREE STRONG POSITIVE HEIGHT
ANOMALIES. THE FIRST IS THROUGH THE BERING SEA WHILE THE SECOND AND
THIRD MERGE BETWEEN THE NORTH POLE AND THE DAVIS STRAIT.
TELECONNECTIONS FROM EACH AREA SUPPORT RIDGING JUST OFF THE WEST
COAST WITH BROAD TROUGHING FROM THE CENTRAL CONUS EASTWARD. THIS
VERY NEGATIVE AO PATTERN SUPPORTS BELOW NORMAL TEMPERATURES EAST OF
THE ROCKIES WITH THE POLAR FRONT ALONG THE GULF COAST.
WEATHER CHALLENGE DURING THIS TIME FRAME IS WHETHER ANY SORT OF
CYCLOGENESIS CAN TAKE PLACE ALONG THIS POLAR FRONT WHICH WILL BE
SITUATED SOUTH OF OUR FCST AREA...AND IF SO CAN ANY OF THIS ENERGY
GAIN ANY LATITUDE PER STRONG WESTERLIES WITHIN THE COLD TROUGH WHICH
WILL BE DIRECTLY OVERHEAD DURING THE PERIOD. FORECAST
SPREAD/UNCERTAINTY AND RUN-RUN CONTINUITY INCREASES SIGNIFICANTLY
HEADING INTO NEXT WEEKEND. RECENT ECMWF/ECMWF ENSEMBLES IN
PARTICULAR HAVE OFFERED MORE SUPPRESSED SOLUTIONS THAN RECENT
GFS/GEFS. THE GFS RUNS INSTEAD OFFER A DEEPER SERN US/MID-ATLC
COASTAL STORM. ENSEMBLES ARE MIXED/IN THE MIDDLE BUT OVERALL FAVOR
A SOLUTION WITH EMPHASIS OVER THE SRN/SERN US...THAT SOME SORT OF
SYSTEM WILL GET GENERATED. SINCE THERE IS NO SOLID CONSENSUS ON
HOW FAR NORTH THIS SYSTEM WILL TRACK...WILL ADVERTISE CHC POPS FOR
THE ENTIRE CWA...WITH FOCUS ON THE SUNDAY TIME FRAME...DAY 7. AS
LUCK WOULD HAVE IT...WINTER ISN`T OVER...SO PTYPE CHALLENGE WILL
ALSO COME INTO PLAY IF THE SYSTEM SPREADS ANY MOISTURE THIS FAR
NORTH.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 140 AM EDT MONDAY...
FLYING CONDITIONS WILL REMAIN POOR THROUGH THIS PERIOD..AS COLD
AIR DAMMING KEEPS LOW CIGS AND AT TIMES VSBYS AROUND OVER MOST OF
THE FORECAST AREA. MAY SEE SOME IMPROVEMENT TO MVFR AT BLF/LWB
LATE THIS MORNING BEFORE MORE RAIN MOVES IN DURING THE AFTN.
COLD ENOUGH TEMPS AT THE SFC MAY LEAD TO SOME FZDZ AT BCB...WHILE
LWB WILL SEE A PERIOD OF LIGHT SNOW/SLEET FOR A COUPLE HOURS THIS
MORNING. MAINLY SEEING PRECIP TAPERING TO DRIZZLE...BUT COULD BE
SOME LIGHT SNOW MIXED IN AT LYH EARLY AS WELL.
THERE APPEARS TO BE SOME HINT OF LOW LVL WIND SHEAR AND MODELS
AGREE THAT BLF WILL BE A PERIOD OF THIS AROUND 10Z TO 15Z TODAY.
MAY SEE A BETTER SETUP FOR THIS TOWARD THE END OF THIS TAF PERIOD
BEFORE THE WEDGE BREAKS AND AHEAD OF THE FRONT...BUT GIVEN THE
NATURE OF THE FORECAST WITH RAIN...LEFT IT OUT FOR NOW.
THE WEDGE IS EXPECTED TO LAST THROUGH MONDAY BEFORE THE FRONTAL
BOUNDARY FINALLY KICKS IT OUT AND BEGINS TO IMPROVE CONDITIONS.
TUESDAY THROUGH FRIDAY WILL BE MUCH IMPROVED ACROSS THE REGION. SOME
UPSLOPE SNOW SHOWERS ARE POSSIBLE AT BLF WEDNESDAY AFTERNOON AND
EVENING. THE WINDS WILL PICK UP DRAMATICALLY ON TUESDAY AND
WEDNESDAY ACROSS THE WEST...EXPECT 25-30KT GUSTS AT TIMES FOR
BLF/BCB/LWB/ROA. DESPITE THE WINDS VFR CONDITIONS ARE EXPECTED FOR
THE VAST MAJORITY OF THE REMAINING TAF PERIOD.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR VAZ018>020-023-024-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 2 PM EDT
MONDAY FOR WVZ045.
&&
$$
SYNOPSIS...SK
NEAR TERM...AMS/SK
SHORT TERM...PM
LONG TERM...PM
AVIATION...CF/WP
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1143 PM CDT SUN MAR 17 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...SUNDAY NIGHT AND MONDAY
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
CENTERED ACROSS THE CENTRAL GREAT LAKES EARLY THIS AFTERNOON. LIGHT
EAST FLOW OFF LAKE MICHIGAN IS PUSHING CLOUDS AND FLURRIES INTO THE
SHORELINE AREAS...BUT TOO MUCH DRY AIR IN PLACE TO REACH THE FOX
VALLEY. THE NEXT STORM SYSTEM IS EMERGING INTO THE NORTHERN PLAINS
AND LOOKS FAIRLY IMPRESSIVE ON SATELLITE IMAGERY. AS THIS CYCLONE
MOVES ACROSS THE AREA TOMORROW...SNOW AMOUNTS AND HEADLINES ARE THE
MAIN FORECAST CONCERNS.
TONIGHT...HIGH PRESSURE WILL SLIDE TO NEW ENGLAND AS THE NEXT STORM
SYSTEM MOVES EAST ACROSS THE PLAINS. MID AND HIGH CLOUDS WILL BE ON
THE INCREASE THROUGH THE NIGHT...AS THE LOW LEVEL PRESSURE GRADIENT
TIGHTENS. AS A RESULT OF MORE CLOUDS AND WIND...TEMPS WILL BE
SIGNIFICANTLY WARMER THAN LAST NIGHT AND MAINLY IN THE TEENS. THE
12Z MODEL SUITE SHOWS A SIMILAR TIMING OF THE ARRIVAL OF THE PRECIP
COMPARED TO WHAT THE PREVIOUS SHIFT SHOWED IN THE FORECAST.
THEREFORE...WILL ONLY SHOW SMALL CHANCES SNEAKING INTO CENTRAL
WISCONSIN BETWEEN 09-12Z.
MONDAY...THE STRONG SHORTWAVE WILL SWING AROUND THE NORTHERN
MISSISSIPPI VALLEY AND BECOME NEGATIVELY TILTED AS IT REACHES
CENTRAL WISCONSIN BY 00Z TUESDAY. SURFACE LOW PRESSURE WILL SHIFT
EAST FROM NORTHERN MINNESOTA TO NORTHERN WISCONSIN DURING THIS SAME
TIME. AS THE PREVIOUS SHIFT MENTIONED...THE SHORTWAVE WILL BRING
STRONG DYNAMICS AND MIXING RATIOS OF ABOUT 3 G/KG...WHICH WILL BE
SUFFICIENT TO PRODUCE SNOWFALL RATES OF AROUND A HALF INCH TO UP TO
ONE INCH PER HOUR (FOR BRIEF PERIODS OF TIME). THE BAND OF SNOW
SHOULD BE PROGRESSIVE...HOWEVER...AND LAST FOR AROUND 6 HOURS OR
SO. IN ADDITION...THE DENDRITIC GROWTH ZONE IS PRETTY HIGH AND NOT
THAT THICK....AND SURFACE TEMPS WILL BE APPROACHING 32 DEGREES OVER
NE WISCONSIN. THEREFORE...EXPECT LOWER SNOWFALL RATIOS THAT WHAT
THE MODELS INDICATE (13-15 TO 1) AND MORE LIKE 10-13:1. WITH
WIDESPREAD QPF AROUND 0.25-0.35...THIS WOULD PUT SNOWFALL AMOUNTS
AROUND 2-4 INCHES FOR MOST LOCATIONS (HIGHER OVER CENTRAL
WISCONSIN). BECAUSE OF FAIRLY BEEFY SNOWFALL RATES DESPITE SOME
AREAS BEING MARGINAL FOR ADVISORY CRITERIA SNOW...WILL ISSUE A
WINTER WEATHER ADVISORY FOR AREAS EXCEPT THE SOUTHERN FOX VALLEY AND
CENTRAL LAKE MICHIGAN SHORELINE. WEST WINDS KICK UP LATE MONDAY
AFTERNOON AND INTO MONDAY EVENING...SO WILL EXTEND THE ADVISORY
THROUGH MID EVENING OR SO TO COVER BLOWING AND DRIFTING CONCERNS.
.LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY
PERIOD WILL BE DOMINATED BY BROAD TROF OVER THE CENTRAL US...WITH
WESTERLIES LYING OVER SOUTHERN HALF OF THE U.S. LOOK FOR PROGRESSIVE
PACIFIC SYSTEMS DIVING THRU THE PLAINS INTO SOUTHEAST U.S...LEAVING
NE WI DRY FOR THE MOST PART...WITH TEMPERATURES RUNNING WELL BELOW
NORMAL.
INITIALLY...UPPER LOW TO MOVE ACROSS THE NORTHERN GREAT LAKES MON
NIGHT. WRAP-AROUND MOISTURE AND CYCLONIC FLOW EXPECTED TO BRING
LIGHT SNOW ACROSS NE WI THRU AT LEAST THE FIRST HALF OF MONDAY NIGHT.
STRONG CAA AND GUSTY WEST WINDS EXPECTED MON NIGHT INTO TUE.
THOUGH WITH CLOUDS AND WINDS...BUMPED MIN TEMPS UP SLIGHTLY FROM
EARLIER SHIFT.
QUESTION THROUGH THE TUE THROUGH WED PERIOD...IS WAVES ROTATING
AROUND THE UPPER LOW AND CHANCE FOR LIGHT PCPN WITH EACH SYSTEM.
DID NOT MAKE CHANGE TO TUE FLURRY FORECAST...THOUGH POTENTIAL
EXIST FOR LIGHT SNOW ON WED...WITH TROF DROPPING SOUTH THROUGH
STATE.
LAKE EFFECT POSSIBLE TUE INTO THU WITH INCOMING COLD AIR MASS AND
MOISTURE CIRCULATING AROUND LOW...THOUGH WITH A W-NW WIND...THE
BETTER ACCUMULATION VALUES ARE EXPECTED TO STAY NORTH OF THE MI/WI
BORDER WITH A TENTH OR TWO OVER NW VILAS COUNTY POSSIBLE.
SOME WEAKENING OF THE BLOCKY PATTERN AT END OF MODEL RUN...THOUGH
NO GREAT WARM-UP IN SIGHT. SPRING POSTPONED FOR AT LEAST ANOTHER
WEEK. DROPPED MAX/MINS TO BELOW GUIDANCE VALUES AS CLIMO EXERTING
TOO MUCH INFLUENCE.
&&
.AVIATION...VFR CONDITIONS EXPECTED THROUGH THE NIGHT BUT IFR CIGS
AND VSBYS WILL ARRIVE FROM WEST TO EAST MONDAY AS AN AREA OF SNOW
ARRIVES AHEAD OF A LOW PRESSURE SYSTEM MOVING ACROSS NORTHERN
MINNESOTA. A 3 TO 5 HOUR PERIOD OF STEADY SNOW IS EXPECTED IN MOST
PLACES. THE SNOW WILL DIMINISH TO SNOW SHOWERS MONDAY EVENING
THOUGH GUSTY WESTERLY SURFACE WINDS MAY PRODUCER BLOWING AND
DRIFTING SNOW.
RDM
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 7 AM TO 10 PM CDT MONDAY FOR WIZ005-
010-018-019-030-031-035>037-045.
WINTER WEATHER ADVISORY FROM 10 AM TO 10 PM CDT MONDAY FOR
WIZ011>013-020>022-038-039-073-074.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1138 PM CDT SUN MAR 17 2013
.SHORT TERM...TONIGHT INTO TOMORROW
920 PM CDT SUN MAR 17 2013
NO CHANGES FORTHCOMING WITH THE LOCAL HEADLINES AS CONDITIONS
STILL LOOK LIKE THEY WILL RAPIDLY DETERIORATE OVERNIGHT. THE BAND
OF SNOW THAT WILL MOVE THROUGH THE REGION IS CURRENTLY OVER SIOUX
FALLS SOUTH DAKOTA AND IS PRODUCING A BRIEF PERIOD OF MODERATE TO
HEAVY SNOW WITH VISIBILITY DROPPING TO A HALF MILE OR LESS. 17.23Z
HRRR FORECAST REFLECTIVITY SHOWS THE INITIAL LIGHT SNOW DEVELOPING
ACROSS SOUTHEAST MINNESOTA/NORTHEAST IOWA BETWEEN MIDNIGHT AND 3
AM AND THE HEAVIEST BAND MOVING IN AROUND 4 AM OR LATER. THE MAIN
INITIAL QUESTION IS WITH HOW MUCH SNOW WILL BE ABLE TO DROP OUT OF
THIS BRIEF BAND. DUE TO THE STRONG LOW LEVEL FRONTOGENESIS...EXPECT
THAT THE SNOWFALL RATES WILL BE RATHER INTENSE AT AN INCH OR TWO
INCHES PER HOUR. BUT WITH THE BAND PROGRESSING EASTWARD
QUICKLY...THESE INTENSE SNOWFALL RATES WILL BE BRIEF AND NOT GIVE
A LOT OF TIME FOR THE SNOW TO ACCUMULATE. 17.23Z RAP COBB OUTPUT
STILL PUTS DOWN A SOLID 1 TO 2 INCHES OF SNOW ACROSS THE ADVISORY
AREA WITH HIGH AMOUNTS THE FURTHER NORTH YOU GO. EXPECT TO SEE
SOME HIGHER LOCAL ACCUMULATIONS AS WELL WHERE THE STRONGEST PART OF
THE SNOW BAND ROLLS THROUGH. SO...WILL NOT MAKE ANY CHANGES TO THE
SNOW TOTALS AT THIS POINT.
WILL NOT BE UPGRADING TO A BLIZZARD WARNING FOR THE WIND PRONE
AREAS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA AS THERE REMAINS
SOME UNCERTAINTY WITH THE POTENTIAL FOR A BRIEF PERIOD OF FREEZING
DRIZZLE AFTER THE SNOW FALLS AND BEFORE THE LOW LEVEL COLD FRONT
COMPLETELY MAKES IT THROUGH. 17.23Z RAP BUFKIT SOUNDINGS STILL
SHOW THIS BRIEF PERIOD WHERE THE COLUMN LOSES ICE WITH THE
SATURATED LAYER WARMER THAN -6C AND THERE STILL BEING SOME LOW
LEVEL LIFT THERE. IF THIS FREEZING DRIZZLE DOES OCCUR...IT WILL
HELP TO WEIGH DOWN THE FRESH SNOW AND SUPPRESS IT FROM BLOWING TOO
MUCH. ALSO...SNOW AMOUNTS IN THE 1 TO 2 INCH RANGE WILL LIMIT THE
POTENTIAL FOR BLOWING SNOW/POTENTIAL BLIZZARD CONDITIONS DESPITE
THE WINDS BEING GUSTY IN THE 30-35MPH RANGE.
.LONG TERM...WEDNESDAY THROUGH SUNDAY
235 PM CDT SUN MAR 17 2013
THE MAJORITY OF THE EXTENDED PERIOD LOOKS TO BE RATHER QUIET. HIGH
PRESSURE BUILDS IN BEHIND THE EARLY WEEK STORM SYSTEM AND REMAINS
OVER THE UPPER MIDWEST THROUGH THE END OF THE WORK WEEK. LATEST
12Z MODELS SUGGESTING MAYBE THE POSSIBILITY OF SOME LIGHT
PRECIPITATION FOR NEXT WEEKEND...BUT WITH THE UPCOMING STORM
SYSTEM...HAVE NOT INVESTIGATED THIS AND WILL LET THE MODEL
CONSENSUS GRIDS RIDE.
&&
.AVIATION...THROUGH 06Z TUESDAY
1138 PM CDT SUN MAR 17 2013
FOCUS CONTINUES TO BE WITH THE DETERIORATING CONDITIONS THAT WILL
COME IN THIS MORNING AND THROUGH THE DAY. THE LEADING EDGE OF THE
SNOW BAND IS MAKING ITS WAY EAST ACROSS WESTERN MINNESOTA AND
APPEARS TO BE REACHING RST AROUND 10Z AND LSE AROUND 13Z. SOME
DRIZZLE IS FORMING ACROSS CENTRAL IOWA AND MAY MOVE INTO THE TAF
SITES AHEAD OF THE MAIN SNOW BAND...WHICH COULD BE AN ISSUE WITH
TEMPERATURES AT OR BELOW FREEZING. HAVE NOT MADE MANY CHANGES TO
THE GOING TAFS...BUT DID CHANGE THE 1/2SM SNOW TO A TEMPO GROUP
SINCE CONDITIONS WILL LIKELY BE VARYING AS THIS MAIN SNOW BAND
COMES IN. EXPECT THIS BRIEF PERIOD OF HEAVY SNOW TO CONTINUE AS
LIGHT SNOW UNTIL THE COLD FRONT SWINGS THROUGH IN THE LATE
MORNING/EARLY AFTERNOON. SOME FLURRIES WILL PERSIST...BUT WINDS
WILL BE THE MAIN CONCERN GOING INTO THE AFTERNOON AND EVENING
HOURS. SUSTAINED WINDS WILL SHIFT AROUND TO THE WEST AT ABOUT 20
TO 25 KTS WITH GUSTS UP TO 35 KTS...PARTICULARLY AT RST. THIS WILL
LIKELY CAUSE SOME BLOWING AND DRIFTING SNOW WHICH WILL CAUSE
VISIBILITIES TO REMAIN DOWN THROUGH THE AFTERNOON. CEILINGS WILL
GRADUALLY IMPROVE AS DRIER LOW LEVEL AIR COMES INTO THE REGION.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
235 PM CDT SUN MAR 17 2013
WI...WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO 1 AM CDT TUESDAY FOR
WIZ017-029-032>034-041-042-053.
WINTER WEATHER ADVISORY FROM 7 AM MONDAY TO 1 AM CDT TUESDAY FOR
WIZ043-044.
MN...WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO 1 AM CDT TUESDAY FOR
MNZ079-086>088-094>096.
IA...WINTER WEATHER ADVISORY FROM 4 AM MONDAY TO 1 AM CDT TUESDAY FOR
IAZ008>010-018-019.
&&
$$
SHORT TERM...HALBACH
LONG TERM...04
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
920 AM EDT MON MAR 18 2013
.DISCUSSION...
CURRENT...RADAR MOSAIC LOOP WAS SHOWING AREAS OF LIGHT RAIN
WEAKENING AS THEY MOVED QUICKLY FROM WEST TO EAST ACROSS AREAS NORTH
OF ORLANDO AND FROM OSCEOLA COUNTY INTO SAINT LUCIE COUNTY. FLORIDA
EAST COAST BUOY OBSERVATIONS WERE INDICATING THAT THE SURFACE RIDGE
AXIS WAS LYING ACROSS THE SOUTHERN END OF CENTRAL FLORIDA. THE
SOUTHERN WIND FLOW WAS FEEDING GULF AND CARIBBEAN MOISTURE NORTHWARD
ACROSS SOUTH FLORIDA AND INTO CENTRAL FLORIDA. THE LATEST RUC UPPER
AIR ANALYSIS WAS SHOWING THE CORE OF A 110 KNOT JET STREAM OVERTOP
OF CENTRAL FLORIDA AND VORT MAXES OVER NORTHERN AND SOUTHERN FLORIDA
WHICH WERE SUPPLYING ENOUGH LARGE SCALE ASCENT TO KEEP SKIES MOSTLY
CLOUDY AND TO PRODUCE LIGHT RAIN.
MORNING/AFTERNOON UPDATE...SCATTERED SHOWERS WITH AN ISOLATED
THUNDERSTORM STILL A GOOD FORECAST FOR THE AFTERNOON AND EARLY
EVENING. HIGHER CHANCES FOR SHOWERS AND AN ISOLATED RUMBLE OR TWO OF
THUNDER WILL BE OVER THE SOUTHERN AREAS WHERE DEEPER MOISTURE WAS
LOCATED AND INCREASING LARGE SCALE ASCENT WITH THE APPROACH OF THE
RIGHT REAR QUADRANT OF THE UPPER LEVEL JET. AFTER A BRIEF BREAK IN
MID AND HIGH CLOUDINESS THIS MORNING SKIES SHOULD BECOME MOSTLY
CLOUDY AGAIN THIS AFTERNOON AS THE CIRRUS FROM A MESOSCALE COMPLEX
IN THE EASTERN GULF OF MEXICO MOVES OVERHEAD. ANY BREAKS IN THE
CLOUDINESS WILL ALLOW FOR A QUICK WARM UP SO THE MID 80S OVER THE
SOUTHERN INTERIOR STILL LOOKS A GOOD CALL FOR MAX TEMPERATURES.
&&
.AVIATION...VFR. ISOLATED SHOWERS ON THE RADAR PRESENTATION SUPPORTS
GOING WITH VCSH THIS AFTERNOON AND EVENING.
&&
.MARINE...THE NOAA AND SCRIPPS BUOYS WERE RECORDING SOUTH SOUTHWEST
WINDS 10 TO 15 KNOTS AND 2 TO 3 FOOT COMBINED SEAS. AS NOTED BY THE
MID SHIFT SHORT TERM FORECASTER...THE WAVE WATCH MODEL WAS HAVING
SOME TROUBLE IN DISCERNING WHICH PERIOD TO USE AS IT WAS SHOWING THE
LONGER WAVE PERIODS IN ITS FORECAST WHILE THE BUOYS ARE RECORDING A
MIX OF BOTH THE LONG AND SHORTER WAVE PERIODS.
RIDGE AXIS OVER THE SOUTHERN COASTAL WATERS WILL RESULT IN CONTINUED
LIGHT TO MODERATE SOUTHERLY FLOW OF 10 TO 15 KNOTS. IF THERE IS A
LONG ENOUGH BREAK IN THE CLOUDINESS A SEA BREEZE COULD FORM BUT THE
PREVAILING SOUTH TO SOUTHWEST SYNOPTIC SCALE FLOW WILL HINDER THE
SEA BREEZE/S INLAND PUSH AND CONFINED IT TO THE COASTAL AREA AND
JUST OFF THE BEACHES.
SOME CHANCE FOR LATE AFTERNOON OR EARLY EVENING OFFSHORE MOVING TS
IF POTENTIAL INSTABILITY IS REALIZED.
&&
.FIRE WEATHER...TUE-FRI...LIGHTNING STORMS A POSSIBILITY TUE-WED
AFTERNOON. RH CONCERNS A POSSIBILITY THU WITH GRADUALLY IMPROVING
CONDITIONS ON FRI AS MOISTURE SLOWLY RETURNS AHEAD OF THE NEXT
APPROACHING LOW PRESSURE SYSTEM TOWARDS THE WEEKEND.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...WIMMER
IMPACT WX/LONG TERM...HAGEMEYER
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
1040 AM EDT MON MAR 18 2013
.UPDATE...
14Z SURFACE ANALYSIS SHOWERS A COLD AIR WEDGE ACROSS THE NORTHEAST
CWFA THIS MORNING. WINDS CONTINUE TO SWITCH AROUND TO THE N/NE UNDER
THE WEDGE...REINFORCING THE COOLER AIR. NOT CONFIDENT ON HOW FAR THE
WEDGE WILL BUILD WESTWARD...WILL HAVE TO CONTINUE TO MONITOR THE
OBS. SINCE THE AIRMASS IS MORE STABLE ACROSS THAT PART OF THE
STATE...HAVE CHANCED THE PTYPE TO STRATIFORM AND ADDED PATCHY
DRIZZLE FOR A FEW MORE HOURS THIS MORNING. HOWEVER...AS THE HEAVIER
PRECIP GETS NEARER...IT STILL WON`T BE SURFACE BASED...BUT SHOULD
BECOME MORE CONVECTIVE WITH A SLIGHT CHANCE OF THUNDER.
FURTHER SOUTH...DO THINK MORE SURFACE INSTABILITY WILL BE PRESENT.
ALREADY ON THE VISIBLE SATELLITE IMAGERY CAN SEE A FEW BREAKS IN THE
THIN STRATUS DECK. THOSE AREAS ABLE TO BREAK OUT WILL SEE THE
HIGHEST INSTABILITY. IN ADDITION...60 DEGREE DEWPOINTS ARE BEGINNING
TO CREEP IN ACROSS SOUTHERN AREAS. LARGE SCALE FORCING WILL REMAIN
WELL TO THE NORTH...BUT SRH MAY BE ENHANCED JUST ALONG THE WEDGE
FRONT. LARGE HAIL AND DAMAGING WIND GUSTS WILL BE THE PRIMARY MODES
OF SEVERE WEATHER THIS AFTERNOON...BUT ISOLD TORNADOES ARE POSSIBLE
WHERE THE LOW LEVEL SHEAR IS ENHANCED. EVEN IF AREAS IN THE SOUTH
ARE ABLE TO COMPLETELY CLEAR OUT...DO THINK CLOUDS WILL FILL BACK IN
AS WIDESPREAD AREA OF PRECIP APPROACHES FROM THE NW. THIS SHOULD
HELP LIMIT THE COVERAGE OF SEVERE STORMS. POTENTIAL FOR SEVERE
WEATHER SHOULD BE BETWEEN 2PM AND 10PM AHEAD OF THE ACTUAL FRONT.
HIGH RESOLUTION MODELS SHOW TWO DISTINCT WAVES OF PRECIP. THE FIRST
WAVE IS IN THE AFTERNOON...AND THE SECOND WAVE IS OVERNIGHT WITH THE
FROPA. AGAIN...SINCE WIDESPREAD FORCING REMAINS WELL TO THE
NORTH...THINK CONVECTION WILL BEGIN TO WEAKEN WITH THE LOSS OF
HEATING. THUNDERSTORMS WILL CONTINUE POSSIBLE OVERNIGHT...BUT SEVERE
WEATHER CHANCES SHOULD LESSEN WITH THE LOSS OF SURFACE INSTABILITY.
NLISTEMAA
&&
.PREV DISCUSSION... /ISSUED 735 AM EDT MON MAR 18 2013/
PREV DISCUSSION... /ISSUED 421 AM EDT MON MAR 18 2013/
.STRONG TO SEVERE STORMS EXPECTED TODAY AND TONIGHT...
SHORT TERM /TODAY THROUGH TUESDAY/...
PRIMARY CONCERN THROUGH THE SHORT TERM IS CONVECTION EXPECTED TODAY
THROUGH EARLY TUESDAY ACCOMPANYING FRONTAL PASSAGE. MODELS IN FAIRLY
GOOD AGREEMENT WITH INCREASING PRECIP COVERAGE ACROSS THE AREA
THROUGH THIS AFTERNOON...AHEAD OF THE BOUNDARY...THEN PUSHING THE
FRONT THROUGH THE AREA BY TUESDAY MORNING.
HI RES SHORT TERM MODELS SHOWING TWO WAVES OF PRECIP THROUGH TUESDAY
MORNING...AND PRECIP TODAY WILL BE MORE CONVECTIVE IN NATURE THAN
HAD BEEN EXPECTED OVER THE LAST SEVERAL DAYS. HRRR AND LOCAL WRF
BRING PRECIP INTO THE AREA BY LATE MORNING...AND SPREAD IT EASTWARD
THROUGH THE AFTERNOON. THIS ACTIVITY AND ASSOCIATED CLOUD COVER WILL
IMPACT THE DESTABILIZATION OF THE ATMOSPHERE...BUT EVEN SO...MODELS
STILL SUGGEST ML CAPE OF 700 TO 900 J/KG THROUGH THE AFTERNOON
ACROSS NORTH AND CENTRAL GEORGIA...AND 900-1100 J/KG INTO THE
OVERNIGHT HOURS ACROSS PORTIONS OF CENTRAL AND SOUTH GEORGIA. HAVE
CONTINUED WITH ISOLATED THUNDER MENTION THROUGH THE MORNING
HOURS...AND THEN PREDOMINATE THUNDERSTORMS THROUGH THE EVENING.
MODELS CONTINUE TO ADVERTISE WEDGE IN PLACE THROUGH THE DAY...WHICH
WILL SUPPORT A MORE STABILIZED ENVIRONMENT ACROSS NORTHEAST GEORGIA.
THAT BEING SAID...THE PERIPHERY OF THE WEDGE WILL SUPPORT LOCALIZED
ENHANCED SRH AND THE DEVELOPMENT OF STRONG TO SEVERE STORMS. THIS
INCREASED LOW-LEVEL SHEAR COULD SUPPORT ISOLATED TORNADOES. PRIMARY
CONCERNS ACROSS THE AREA WILL BE DAMAGING WINDS AND LARGE
HAIL...ESPECIALLY IN ORGANIZED BANDS OF CONVECTION. ROTATION IS
POSSIBLE WITHIN STRONGER UPDRAFTS IN ORGANIZED STORMS.
SEVERE POTENTIAL DOES DIMINISH SOMEWHAT IN THE OVERNIGHT HOURS...AND
SOME MODELS ARE SUGGESTING A LESS ORGANIZED BAND OF ACTIVITY
ACCOMPANYING THE FRONT THROUGH THE AREA OVERNIGHT INTO TUESDAY
MORNING. WITH SOME UNCERTAINTY ON TIMING AND STRENGTH OF THE
ACTIVITY...HAVE GENERALLY GONE WITH SLIGHTLY LESS THAN CATEGORICAL
POPS AND SCATTERED THUNDERSTORMS FOCUSED ALONG THE BOUNDARY
OVERNIGHT. PRECIP CHANCES SHOULD DROP OFF QUICKLY BEHIND THE
FRONT...SO HAVE LIMITED POPS AND TS MENTION FOLLOWING THE FROPA.
FRONT IS EXPECTED TO PUSH THROUGH THE CWA BY TUESDAY
AFTERNOON...WITH A DRIER AND COOLER AIR MASS IN PLACE AS A RESULT.
THIS AIR MASS WILL REMAIN IN PLACE INTO THE EXTENDED FORECAST
PERIODS.
31
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
EXTENDED PERIOD BEGINS WITH THE DEVELOPMENT OF A LONGWAVE EAST
COAST TROUGH WHICH WILL ALLOW FOR TEMPS DROPPING SOME 10 DEGREES
BELOW NORMAL INITIALLY WITH ADDITIONAL SHOTS OF COOL TO COLD AIR
THROUGH WEEKS END. WILL SEE STRONG IMPULSE PUSH THROUGH THE
TENNESSEE VALLEY EARLY WEDNESDAY WITH MAIN FORCING REMAINING JUST
NORTH OF THE GEORGIA MOUNTAINS. MID LEVEL MOISTURE AND LIFT
SUPPORT SLIGHT CHANCE POPS BUT WITH DEWPOINTS REMAINING IN THE
20S...WILL KEEP POPS IN THE SILENT 10 RANGE FOR NOW. THIS WILL
BEAR WATCHING CLOSELY HOWEVER AS IF PRECIP COULD BE
REALIZED...COLD TEMPS ALOFT AND WET BULB EFFECTS LOOK TO EASILY
SUPPORT WINTRY PRECIP FOR THE NORTHERN TIER.
NEST SYSTEM WILL TAKE SHAPE FRIDAY OVER THE SOUTHERN PLAINS AS
SOUTHERN STREAM OF THE JET GETS ACTIVE AND DEVELOPS LOW PRESSURE
OVER EAST TEXAS. FAVORABLE LARGE SCALE ISENTROPIC ASCENT PROFILE
FOR THE GULF COAST INCLUDING THE LOCAL AREA THROUGH FRIDAY. WILL
HAVE TO MONITOR ONSET CLOSELY FOR THIS SYSTEM AS COLD AIR REMAINS
TRAPPED IN THE MOUNTAINS INITIALLY WHICH COULD LEAD TO ADDITIONAL
WINTRY WX CONCERNS. WARM BELT SHOULD CONTINUE TO LIFT NORTH AS
PRECIP BECOMES MORE ENTRENCHED OVER THE AREA WITH ALL RAIN
EXPECTED FOR THE REMAINDER OF THE TENURE OF THIS STORM SYSTEM.
SIGNIFICANT DIFFERENCES AMONG THE ECMWF AND GFS BY THIS TIME
PERIOD WITH EURO CLEARING IT OUT A BIT FASTER BUT BRINGING IN NEXT
SYSTEM MUCH FURTHER SOUTH THAN GFS. MOST CONFIDENCE IS FOR LATE
FRI AND EARLY SAT AND INCREASED POPS TO HIGH END CHANCE THIS FAR
OUT BUT FORECAST WILL LIKELY REQUIRE SIGNIFICANT TWEAKS WITH
SUBSEQUENT ISSUANCES.
DEESE
AVIATION...
12Z UPDATE...
HIGH IFR/LOW MVFR CIGS ACROSS THE AREA THIS MORNING WILL BECOME
GENERALLY MVFR BY LATE MORNING AND VFR BY AFTERNOON DUE TO MIXING
FROM PRECIP ACTIVITY. ALTHOUGH SHOWERS ARE DEVELOPING THIS
MORNING...EXPECT FIRST WAVE OF PRECIP TO BE LATE MORNING THROUGH
AFTERNOON AND ACCOMPANIED BY GREATEST THUNDERSTORM THREAT. THE
SECOND WAVE WILL BE OVERNIGHT WITH THE FRONTAL PASSAGE...WITH
LOWER TS CHANCES. SSE WINDS THIS MORNING WILL BECOME SSW AT 8-11KT BY
THIS AFTERNOON. WITH FRONTAL PASSAGE EXPECT WINDS TO SHIFT TO THE
WEST AT 9-11KT AND WILL BE WNW AT 12-15 G20-23KT TUESDAY. QUICKLY
CLEARING CONDITIONS ARE EXPECTED AFTER 10-12Z TUESDAY.
//ATL CONFIDENCE...12Z UPDATE...
HIGH CONFIDENCE ON WINDS.
LOW TO MEDIUM CONFIDENCE ON TIMING OF TS THIS AFTERNOON.
MEDIUM CONFIDENCE ON ALL OTHER ELEMENTS.
31
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 62 48 67 36 / 90 90 40 5
ATLANTA 68 47 64 39 / 90 90 30 5
BLAIRSVILLE 58 42 57 31 / 90 80 20 5
CARTERSVILLE 68 45 63 33 / 90 80 20 5
COLUMBUS 74 54 68 41 / 90 80 40 5
GAINESVILLE 60 45 63 37 / 90 90 30 5
MACON 72 54 70 38 / 90 80 50 5
ROME 70 44 64 33 / 90 80 20 10
PEACHTREE CITY 70 49 65 32 / 90 80 30 5
VIDALIA 77 60 74 45 / 90 90 40 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
735 AM EDT MON MAR 18 2013
.PREV DISCUSSION... /ISSUED 421 AM EDT MON MAR 18 2013/
..STRONG TO SEVERE STORMS EXPECTED TODAY AND TONIGHT...
SHORT TERM /TODAY THROUGH TUESDAY/...
PRIMARY CONCERN THROUGH THE SHORT TERM IS CONVECTION EXPECTED TODAY
THROUGH EARLY TUESDAY ACCOMPANYING FRONTAL PASSAGE. MODELS IN FAIRLY
GOOD AGREEMENT WITH INCREASING PRECIP COVERAGE ACROSS THE AREA
THROUGH THIS AFTERNOON...AHEAD OF THE BOUNDARY...THEN PUSHING THE
FRONT THROUGH THE AREA BY TUESDAY MORNING.
HI RES SHORT TERM MODELS SHOWING TWO WAVES OF PRECIP THROUGH TUESDAY
MORNING...AND PRECIP TODAY WILL BE MORE CONVECTIVE IN NATURE THAN
HAD BEEN EXPECTED OVER THE LAST SEVERAL DAYS. HRRR AND LOCAL WRF
BRING PRECIP INTO THE AREA BY LATE MORNING...AND SPREAD IT EASTWARD
THROUGH THE AFTERNOON. THIS ACTIVITY AND ASSOCIATED CLOUD COVER WILL
IMPACT THE DESTABILIZATION OF THE ATMOSPHERE...BUT EVEN SO...MODELS
STILL SUGGEST ML CAPE OF 700 TO 900 J/KG THROUGH THE AFTERNOON
ACROSS NORTH AND CENTRAL GEORGIA...AND 900-1100 J/KG INTO THE
OVERNIGHT HOURS ACROSS PORTIONS OF CENTRAL AND SOUTH GEORGIA. HAVE
CONTINUED WITH ISOLATED THUNDER MENTION THROUGH THE MORNING
HOURS...AND THEN PREDOMINATE THUNDERSTORMS THROUGH THE EVENING.
MODELS CONTINUE TO ADVERTISE WEDGE IN PLACE THROUGH THE DAY...WHICH
WILL SUPPORT A MORE STABILIZED ENVIRONMENT ACROSS NORTHEAST GEORGIA.
THAT BEING SAID...THE PERIPHERY OF THE WEDGE WILL SUPPORT LOCALIZED
ENHANCED SRH AND THE DEVELOPMENT OF STRONG TO SEVERE STORMS. THIS
INCREASED LOW-LEVEL SHEAR COULD SUPPORT ISOLATED TORNADOES. PRIMARY
CONCERNS ACROSS THE AREA WILL BE DAMAGING WINDS AND LARGE
HAIL...ESPECIALLY IN ORGANIZED BANDS OF CONVECTION. ROTATION IS
POSSIBLE WITHIN STRONGER UPDRAFTS IN ORGANIZED STORMS.
SEVERE POTENTIAL DOES DIMINISH SOMEWHAT IN THE OVERNIGHT HOURS...AND
SOME MODELS ARE SUGGESTING A LESS ORGANIZED BAND OF ACTIVITY
ACCOMPANYING THE FRONT THROUGH THE AREA OVERNIGHT INTO TUESDAY
MORNING. WITH SOME UNCERTAINTY ON TIMING AND STRENGTH OF THE
ACTIVITY...HAVE GENERALLY GONE WITH SLIGHTLY LESS THAN CATEGORICAL
POPS AND SCATTERED THUNDERSTORMS FOCUSED ALONG THE BOUNDARY
OVERNIGHT. PRECIP CHANCES SHOULD DROP OFF QUICKLY BEHIND THE
FRONT...SO HAVE LIMITED POPS AND TS MENTION FOLLOWING THE FROPA.
FRONT IS EXPECTED TO PUSH THROUGH THE CWA BY TUESDAY
AFTERNOON...WITH A DRIER AND COOLER AIR MASS IN PLACE AS A RESULT.
THIS AIR MASS WILL REMAIN IN PLACE INTO THE EXTENDED FORECAST
PERIODS.
31
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
EXTENDED PERIOD BEGINS WITH THE DEVELOPMENT OF A LONGWAVE EAST
COAST TROUGH WHICH WILL ALLOW FOR TEMPS DROPPING SOME 10 DEGREES
BELOW NORMAL INITIALLY WITH ADDITIONAL SHOTS OF COOL TO COLD AIR
THROUGH WEEKS END. WILL SEE STRONG IMPULSE PUSH THROUGH THE
TENNESSEE VALLEY EARLY WEDNESDAY WITH MAIN FORCING REMAINING JUST
NORTH OF THE GEORGIA MOUNTAINS. MID LEVEL MOISTURE AND LIFT
SUPPORT SLIGHT CHANCE POPS BUT WITH DEWPOINTS REMAINING IN THE
20S...WILL KEEP POPS IN THE SILENT 10 RANGE FOR NOW. THIS WILL
BEAR WATCHING CLOSELY HOWEVER AS IF PRECIP COULD BE
REALIZED...COLD TEMPS ALOFT AND WET BULB EFFECTS LOOK TO EASILY
SUPPORT WINTRY PRECIP FOR THE NORTHERN TIER.
NEST SYSTEM WILL TAKE SHAPE FRIDAY OVER THE SOUTHERN PLAINS AS
SOUTHERN STREAM OF THE JET GETS ACTIVE AND DEVELOPS LOW PRESSURE
OVER EAST TEXAS. FAVORABLE LARGE SCALE ISENTROPIC ASCENT PROFILE
FOR THE GULF COAST INCLUDING THE LOCAL AREA THROUGH FRIDAY. WILL
HAVE TO MONITOR ONSET CLOSELY FOR THIS SYSTEM AS COLD AIR REMAINS
TRAPPED IN THE MOUNTAINS INITIALLY WHICH COULD LEAD TO ADDITIONAL
WINTRY WX CONCERNS. WARM BELT SHOULD CONTINUE TO LIFT NORTH AS
PRECIP BECOMES MORE ENTRENCHED OVER THE AREA WITH ALL RAIN
EXPECTED FOR THE REMAINDER OF THE TENURE OF THIS STORM SYSTEM.
SIGNIFICANT DIFFERENCES AMONG THE ECMWF AND GFS BY THIS TIME
PERIOD WITH EURO CLEARING IT OUT A BIT FASTER BUT BRINGING IN NEXT
SYSTEM MUCH FURTHER SOUTH THAN GFS. MOST CONFIDENCE IS FOR LATE
FRI AND EARLY SAT AND INCREASED POPS TO HIGH END CHANCE THIS FAR
OUT BUT FORECAST WILL LIKELY REQUIRE SIGNIFICANT TWEAKS WITH
SUBSEQUENT ISSUANCES.
DEESE
&&
.AVIATION...
12Z UPDATE...
HIGH IFR/LOW MVFR CIGS ACROSS THE AREA THIS MORNING WILL BECOME
GENERALLY MVFR BY LATE MORNING AND VFR BY AFTERNOON DUE TO MIXING
FROM PRECIP ACTIVITY. ALTHOUGH SHOWERS ARE DEVELOPING THIS
MORNING...EXPECT FIRST WAVE OF PRECIP TO BE LATE MORNING THROUGH
AFTERNOON AND ACCOMPANIED BY GREATEST THUNDERSTORM THREAT. THE
SECOND WAVE WILL BE OVERNIGHT WITH THE FRONTAL PASSAGE...WITH
LOWER TS CHANCES. SSE WINDS THIS MORNING WILL BECOME SSW AT 8-11KT BY
THIS AFTERNOON. WITH FRONTAL PASSAGE EXPECT WINDS TO SHIFT TO THE
WEST AT 9-11KT AND WILL BE WNW AT 12-15 G20-23KT TUESDAY. QUICKLY
CLEARING CONDITIONS ARE EXPECTED AFTER 10-12Z TUESDAY.
//ATL CONFIDENCE...12Z UPDATE...
HIGH CONFIDENCE ON WINDS.
LOW TO MEDIUM CONFIDENCE ON TIMING OF TS THIS AFTERNOON.
MEDIUM CONFIDENCE ON ALL OTHER ELEMENTS.
31
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 62 48 67 36 / 90 90 40 5
ATLANTA 68 47 64 39 / 90 90 30 5
BLAIRSVILLE 58 42 57 31 / 90 80 20 5
CARTERSVILLE 68 45 63 33 / 90 80 20 5
COLUMBUS 74 54 68 41 / 90 80 40 5
GAINESVILLE 60 45 63 37 / 90 90 30 5
MACON 72 54 70 38 / 90 80 50 5
ROME 70 44 64 33 / 90 80 20 10
PEACHTREE CITY 70 49 65 32 / 90 80 30 5
VIDALIA 77 60 74 45 / 90 90 40 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...31
LONG TERM....DEESE
AVIATION...31
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
1057 AM CDT MON MAR 18 2013
.DISCUSSION...
1055 AM CDT
CONTINUING TO MONITOR OBSERVATIONAL AND SHORT TERM GUIDANCE AS
LATE SEASON LIGHT WINTRY PRECIP EVENT CONTINUES. WE HAVE HOWEVER
LET THE ADVISORY END AT 11 AM AS INITIALLY PLANNED...DUE MAINLY
TO THE THREAT OF APPRECIABLE FREEZING PRECIPITATION HAVING ENDED.
ONE SHORT WAVE IMPULSE IS CURRENTLY PROGRESSING NORTHEAST OVER
LAKE MI AND WAS RESPONSIBLE FOR OUR EARLY MORNING LIGHT
ACCUMULATIONS. THE PRIMARY UPPER WAVE IS APPROACHING QUICKLY ACROSS
IA AND IS VERY WELL-DEFINED ON THE WATER VAPOR CHANNEL. WEAK WARM
AND MOIST ADVECTION ALOFT CONTINUES ACROSS THE SOUTHERN AND
EASTERN AREA...BUT A GOOD PART OF THE MOISTURE TRANSPORT WAS AND
CONTINUES TO BE ROBBED BY OHIO VALLEY/LOWER MISSISSIPPI VALLEY
CONVECTION. STILL GETTING SPOTTER REPORTS AND PUBLIC REPORTS
THROUGH THE NSSL MPING APPLICATION OF LIGHT FREEZING PRECIPITATION
ACROSS CHICAGO...AND RECENT AMDAR SOUNDINGS DO SUPPORT A LIGHT MIX.
WITH CONTINUED LIGHT ARCED RADAR ECHOES OF AN ISENTROPIC ASCENT
NATURE SHOWING UP ACROSS CHICAGO INTO NORTHWEST INDIANA...WILL
CONTINUE THE MENTION FOR LIGHT FREEZING PRECIP/SLEET IN THE
FORECAST FOR THOSE AREAS INTO EARLY AFTERNOON. WITH THE LIGHT
RATES AND TEMPERATURES HAVING INCHED UP TO THE 30 TO 32
MARK...EXPECTING ANY ICE ACCUMULATION TO BE LIGHT.
AS THE UPPER WAVE PROGRESSES IN...ELEVATED STEEP LAPSE RATES IN
TANDEM WITH DEEPER MOISTURE SUPPORT THE POTENTIAL FOR MODEST
SNOW/SNOW SHOWERS MOVING ACROSS NORTHERN IL...ESPECIALLY ALONG AND
NORTH OF I-88. THIS POTENTIAL IS VERIFIED WITH NUMEROUS EASTERN IA
LOCATIONS HAVING REPORTED VISIBILITY UNDER 1SM. HIGH RES
REFLECTIVITY PRODUCING MODELS SHOW CONTINUED ENHANCEMENT AS THIS
AREA PROGRESSES EAST ACROSS NORTHERN IL THROUGH EARLY TO MID
AFTERNOON WHICH MAKES SENSE WITH THE AFOREMENTIONED FORCING.
SCATTERED HEAVY RATES ARE POSSIBLE AT TIMES...ESPECIALLY IN THE WI
BORDER COUNTIES. DO NOT WANT TO DOWNPLAY TEMPORARY IMPACTS TO
TRAVEL ESPECIALLY WITH BURSTS OF HEAVIER RATES...BUT WILL MENTION
THAT IN AN SPS AS OPPOSED TO EXTENDING THE ADVISORY AS ADDITIONAL
SNOWFALL ACCUMULATIONS LOOK TO BE ON THE ORDER OF ONE TO MAYBE TWO
INCHES AT MOST AND THE FREEZING PRECIP THREAT ENDING FROM WEST TO
EAST.
MTF
&&
.PREV DISCUSSION...
529 AM CDT
A WINTER ADVISORY HAS BEEN ISSUED FOR A PORTION OF NORTHERN
ILLINOIS AND NORTHWEST INDIANA THROUGH 11 AM...WITH SLEET AND
FREEZING RAIN THE MAIN CONCERNS.
LATEST RADAR IMAGERY CONTINUES TO SHOW PRECIP SHIELD BLOSSOMING
EARLY THIS MORNING AS LARGE SCALE FORCING INCREASES ACROSS THE
AREA. THIS FORCING COINCIDING WITH A THERMAL PROFILE SUPPORTIVE OF
A WINTRY MIX...HAS RESULTED IN WIDESPREAD SLEET AND FREEZING RAIN
BEING REPORTED. AT THE OFFICE HERE IN ROMEOVILLE...MORE SLEET
ACCUMULATION HAS BEEN NOTICED OVER THE LAST HOUR. THIS SLEET
ACCUMULATION AS WELL AS THE FURTHER BLOSSOMING OF THE PRECIP
SHIELD IS WHAT HAS PROMPTED THE ADVISORY. ALTHOUGH ANY SNOW/SLEET
ACCUMULATION WILL REMAIN RATHER MINOR AROUND AN INCH...ITS ONCE
AGAIN THE SLEET ACCUMULATION COINCIDING WITH LIGHT FREEZING RAIN
WHICH IS THE MAIN CONCERN...CONCERNS OF SLIPPERY CONDITIONS FOR
THE MORNING COMMUTE. STILL EXPECT FURTHER SNOW ACCUMULATION LATER
THIS MORNING INTO THE AFTERNOON...BUT WITH SNOW THE LIKELY PRECIP
TYPE.
RODRIGUEZ
//PREV DISCUSSION...
406 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH A
WINTRY MIX OF PRECIP ONGOING...AND THEN CONTINUING THROUGH THE
REMAINDER OF THE DAY WITH SNOW LIKELY ACROSS THE NORTHERN THIRD OF
THE CWA WHILE A RAIN/SNOW MIX FURTHER SOUTH TOWARDS THE I80
CORRIDOR...AND THEN ALL RAIN ACROSS THE SOUTHERN TIER OF COUNTIES.
LATEST RADAR IMAGERY IS DEPICTING AN AREA OF PRECIPITATION
SPREADING NORTH ACROSS PARTS OF NORTHEAST ILLINOIS AND NORTHWEST
INDIANA AS AN MID LEVEL WAVE TRACKS NORTHEAST ACROSS THE REGION.
LATEST REPORTS CONTINUE TO SUPPORT A WINTRY MIX THAT HAS BEEN
ANTICIPATED WITH SNOW OR SLEET FALLING ON THE NORTHERN FRINGE OF
THIS PRECIP SHIELD FROM STREATOR IN ILLINOIS EAST TO RENSSELAER IN
INDIANA...WHILE A RAIN SNOW MIX HAD BEEN REPORTED JUST SOUTH OF
THIS LINE. OVER THE NEXT COUPLE OF HOURS THIS TREND WILL LIKELY
CONTINUE AS THIS WINTRY MIX MOVES NORTH TOWARD THE CHICAGO METRO
AREA. ALTHOUGH WEAK...LATEST RAP ANALYSIS IS SHOWING SOME WAA
AIDING IN THIS DEVELOPMENT AND EXPECT THIS WEAK WAA TO FURTHER AID
THIS MORNING UNTIL MORE LARGE SCALE SUPPORT ARRIVES FROM THE WEST.
EXPECT SNOW OR SLEET WITH ONLY MINOR ACCUMULATIONS INITIALLY EARLY
THIS MORNING ALONG AND NORTH OF INTERSTATE 80...JUST SOUTH OF THE
INTERSTATE 80 CORRIDOR A RAIN SNOW MIX WILL BE LIKELY CONTINUE.
SURFACE TEMPS THIS MORNING HAVE BEEN SLOWLY FALLING WITH CURRENT
TEMPS AT OR JUST BELOW FREEZING ACROSS MUCH OF THE CWA. IN THOSE
AREAS WHERE LIGHT RAIN DOES OCCUR...THESE SURFACE TEMPERATURES
WILL SUPPORT THE POTENTIAL FOR BRIDGES AND ELEVATED ROADWAYS TO
ACCUMULATE A THIN LAYER OF ICING. ALTHOUGH THIS WINTRY MIX HAD
BEEN FALLING OVER THE LAST COUPLE OF HOURS...REPORTS HAD NOT
INDICATED ANY WIDESPREAD SLIPPERY CONDITIONS BUT WITH ROADS
REMAINING ONLY WET AT THAT TIME. WOULD SUSPECT THAT SLIPPERY
CONDITIONS ARE CURRENTLY DEVELOPING AND COULD POSSIBLY CONTINUE TO
DEVELOP OVER THE NEXT COUPLE OF HOURS. OF GREATEST CONCERN AT THIS
TIME FOR THESE SLIPPERY CONDITIONS WOULD BE THE I80 CORRIDOR WHERE
CURRENTLY THE STRONGEST RETURNS ON RADAR ARE LOCATED AS WELL AS
WITH SURFACE TEMPS JUST BELOW FREEZING. HAVE REISSUED AN SPS AT
THIS TIME FOR THOSE AREAS...WHILE NOT ISSUING ANY OTHER HEADLINES
AT THIS TIME. FORCING FOR THIS CURRENT PRECIP ACROSS THE CWA
SHOULD EXIT OVER THE NEXT COUPLE OF HOURS...WITH LATEST SHORT TERM
GUIDANCE SHOWING A DIMINISHING TREND WITHIN THE OVERALL EXTENT OF
THIS PRECIP. RESIDENCE TIME FOR ANY FURTHER LINGERING PRECIP IN
THESE AREAS SHOULD BE LIMITED THIS MORNING...AS THIS PRECIP AXIS
SLOWLY LIFTS NORTH. ALTHOUGH A DIMINISHING TREND HERE IN THE NEAR
TERM IS LIKELY...ONCE AGAIN STILL ANTICIPATE A NORTHWARD PUSH OF
THIS PRECIP.
LARGE SCALE FORCING FOR ASCENT WILL INCREASE THROUGH MID MORNING
AS THE CURRENT UPPER LEVEL TROUGH JUST TO THE WEST PUSHES EAST.
THIS IS ALREADY BEGINNING TO OCCUR OVER AREAS IN EASTERN IOWA
WHERE LIGHT RETURNS ARE BEGINNING TO SHOW UP ON RADAR. EXPECT
FURTHER DEVELOPMENT THROUGH MID TO LATE MORNING WITH A MIXED BAG
OF PRECIPITATION STILL LIKELY. ALTHOUGH...LATEST GUIDANCE IS
SHOWING THAT COLDER AIR WILL BE IN PLACE FURTHER SOUTH ACROSS THE
CWA THAN PREVIOUSLY ANTICIPATED WITH THE NUDGE OF WARMER AIR ALOFT
NOT AS PRONOUNCED FOR THIS MORNING OR MOST OF THE DAY...WITH
LATEST AMDAR SOUNDINGS SUPPORTED THESE THERMAL PROFILES. WITH THAT
IN MIND...HAVE SNOW OR SLEET POSSIBLE THROUGH MID MORNING FOR THE
NORTHERN HALF OF THE CWA ACROSS NORTH CENTRAL AND NORTHEAST
ILLINOIS WITH MORE LIQUID TYPE PRECIP EXPECTED FURTHER SOUTH.
SURFACE TEMPS WILL BE RISING THROUGH MID MORNING WITH ANY FURTHER
THREAT OF FREEZING RAIN IN THE CURRENT LOCATIONS BECOMING LESS
LIKELY. AS THIS UPPER LEVEL TROUGH SWINGS ACROSS THIS SNOW/SLEET
AND THEN SNOW THROUGH MID DAY AND EARLY AFTERNOON...DO THINK THERE
WILL BE SOME MINOR ACCUMULATIONS FOR AREAS ALONG AND NORTH OF THE
INTERSTATE 88 CORRIDOR INCLUDING THE WEST/NORTHWEST/NORTHERN
SUBURBS OF CHICAGO. ONE TO TWO INCHES WILL BE POSSIBLE NEAR THE
WISCONSIN BORDER WITH THREE INCHES AN OUTSIDE POSSIBILITY FOR
ISOLATED LOCATIONS...AND AROUND AN INCH FURTHER SOUTH. A TREND
TOWARDS MORE DRIZZLE WILL BE POSSIBLE BY MID AFTERNOON BUT AS THIS
OCCURS...MUCH COLDER AIR WILL BE SWEEPING THROUGH THE CWA. THIS
COULD HELP FOR FURTHER CRYSTALS TO DEVELOP AND HELP LIGHT SNOW TO
LINGER AROUND INTO THE AFTERNOON AND EARLY EVENING BUT WITH LITTLE
OR NO ADDITIONAL ACCUMULATION LIKELY. COLDER TEMPS STILL ON PAR
FOR THIS WEEK...STARTING OFF TONIGHT WITH LOW TO MID TEENS
POSSIBLE ACROSS MUCH OF THE CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* DURATION OF MIXED PRECIP AND TIMING OF TYPE CHANGES.
* VSBY LESS THAN 3SM AS SURFACE CONDITIONS SATURATE WITH ONGOING
LIGHT PRECIPITATION.
* IFR CIGS...WITH IMPROVEMENT TO MVFR LATE THIS AFTERNOON.
* EAST WINDS EASING IN SPEED AND TURNING CLOCKWISE TO BECOME
SOUTHWEST THIS AFTERNOON...FURTHER SHIFT TO WEST LATE AFTERNOON
WITH GUSTS INCREASING TO 30-35 KT THIS EVENING.
* ADDITIONAL SNOW SHOWERS POSSIBLE THIS EVENING.
BMD
//DISCUSSION...UPDATED 12Z...
BAND OF MIXED PRECIP CONTINUE TO LIFT NORTHWARD ACROSS THE
TERMINALS AND HAS BEEN EXPANDING ON ITS SOUTHERN FLANK. HAVE RUN
THE GAMUT OF PRECIP TYPES LAST FEW HOURS BUT EXPECT THAT MDW/GYY
WILL CONTINUE TO HAVE THE BEST CHANCE FOR LIQUID PRECIP /RAIN OR
FREEZING RAIN/ TO MIX IN FOR THE NEXT FEW HOURS WHILE ORD/DPA LOOK
TO REMAIN A COMBINATION OF SNOW AND SLEET...THOUGH CANNOT
COMPLETELY RULE OUT SOME LIQUID FALLING AT THESE SITES FOR A SHORT
TIME. THE WARMER PUNCH CAUSING THE MIXED PRECIP WILL SHIFT EASTWARD
THROUGH LATE MORNING WHICH SHOULD ALLOW MAINLY SNOW TO TAKE
OVER...BUT SURFACE TEMPS WILL BE WARMING...ESPECIALLY SOUTH...SO
SOME RAIN/SNOW COULD OCCUR THROUGH MIDDAY. RFD IS EXPECTED TO
REMAIN MAINLY SNOW THOUGH SOME PELLETS COULD MIX IN. A
TROUGH/FRONT WILL APPROACH FROM THE WEST THIS AFTERNOON AND A BAND
OF SNOW CURRENTLY ACROSS CENTRAL IOWA WILL CROSS THE TERMINALS
TOWARD MIDDAY. THIS MAY START TO MOVE MORE TO THE NORTHEAST SO GYY
MAY SEE THE LEAST IMPACT IN TERMS OF VSBY REDUCTION IN LIGHT SNOW
AS THIS OCCURS. OTHERWISE WILL WORK A PERIOD OF LOWER VSBY ACROSS
THE TERMINALS TO ACCOUNT FOR THIS BAND. RFD SHOULD SEE THE
GREATEST ACCUMULATION WITH AN INCH OR TWO OF SNOW POSSIBLE BY MID
AFTERNOON. ORD/DPA MAY SEE A FEW TENTHS OF SLEET/SNOW ACCUM THIS
MORNING...WITH A FEW MORE TENTHS POSSIBLE WITH THE SECOND BAND
INTO EARLY AFTERNOON...BUT TEMPS ABOVE FREEZING MAY PRECLUDE THIS.
ONCE THE BAND PASSES WINDS WILL TURN WESTERLY AND THEN BECOME VERY
GUSTY LATE THIS AFTERNOON/EARLY THIS EVENING...WITH GUSTS OF 30-35
KT EXPECTED. THIS SHOULD ALSO HELP TO BRING IFR CIGS UP TO MVFR
LATE THIS AFTERNOON BUT IT IS NOT CLEAR HOW MUCH IMPROVEMENT WILL
OCCUR PRIOR TO SUNSET. COLDER AIR WILL BE SPREADING IN SO THERE
MAY BE RE-DEVELOPMENT OF SNOW SHOWERS THIS EVENING...WHICH IF THEY
CAN DEVELOP...COULD BRING SHORT PERIODS OF REDUCED VSBY.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* LOW CONFIDENCE ON SFC TEMPS AND WHEN FZ COMPONENT OF -RA/DZ WILL
END.
* HIGH CONFIDENCE IN IFR CIGS.
* HIGH CONFIDENCE IN WIND TRENDS.
* LOW CONFIDENCE IN ADDITIONAL SNOW SHOWERS DEVELOPING THIS
EVENING.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH SUNDAY...MAINLY VFR...GUSTY WEST WINDS
TUESDAY NIGHT AND WEDNESDAY.
MDB
&&
.MARINE...
323 AM CDT
LOW PRESSURE CONTINUES TO MOVE EAST ACROSS THE EASTERN DAKOTAS AND
WILL REACH EASTERN LAKE SUPERIOR TUESDAY MORNING. ANOTHER LOW IS
ALSO MOVING UP THE OHIO RIVER VALLEY AND WILL MERGE WITH THE MAIN
LOW TUESDAY. EAST TO SOUTHEAST WINDS CONTINUE ACROSS LAKE MICHIGAN
THIS MORNING WITH THE STRONGEST SPEEDS ACROSS THE CENTRAL SECTION OF
THE LAKE. THE PRESSURE GRADIENT WILL WEAKEN THROUGH THE MORNING
ALLOWING SPEEDS TO EASE UP WITH WINDS THEN SHIFTING TO THE WEST AND
SOUTHWEST THROUGH THE AFTERNOON. THE WEAKENING WINDS AND SHIFT IN
DIRECTION SHOULD HELP TO KNOCK WAVES DOWN SO WILL PLAN ON LETTING
THE SMALL CRAFT ADVISORY FOR THE ILLINOIS NEARSHORE WATERS EXPIRE AT
18Z. WEST WINDS WILL RAMP UP TO 35-40 KT GALES ACROSS THE SOUTHERN
TWO-THIRDS OF THE LAKE THIS EVENING WITH THE FAR NORTHERN SECTION
LIKELY BEING HELD TO AROUND 30 KT THANKS TO THE NEARBY PASSAGE OF
THE SURFACE LOW TONIGHT. HAVE UPGRADED THE GALE WATCH TO A GALE
WARNING FOR THE OPEN WATERS. ISSUED A GALE WATCH FOR THE ILLINOIS
NEARSHORE WATERS AS WELL AS THE INDIANA WATERS FROM CALUMET HARBOR
TO GARY...WITH SOME UNCERTAINTY ON WHETHER GALE FORCE WILL BE ABLE
TO BE REACHED GIVEN THE OFFSHORE WIND COMPONENT. HOWEVER...DID
UPGRADE AREAS FROM GARY EAST TO A GALE WARNING GIVEN THEIR BETTER
ONSHORE EXPOSURE. OTHERWISE...TEMPERATURES WILL FALL AS MUCH COLDER
AIR BUILDS IN WHICH WILL SET THE STAGE FOR FREEZING SPRAY. THE LOW
WILL BE SLOW TO DEPART TO THE EAST WHILE HIGH PRESSURE SPREADS INTO
THE NORTHERN PLAINS INTO TUESDAY NIGHT. THIS WILL KEEP WINDS STRONG
INTO TUESDAY EVENING BUT SPEEDS LOOK TO FALL JUST BELOW GALE FORCE
TUESDAY EVENING OR TUESDAY NIGHT...BUT SOME GALE FORCE GUSTS MAY
CONTINUE EVEN THROUGH WEDNESDAY. WILL KEEP 30 KT IN THE FORECAST FOR
THIS TIME FRAME FOR NOW THOUGH. THE PRESSURE GRADIENT WILL GRADUALLY
WEAKEN THROUGH THURSDAY AS THE LOW FILLS TO THE EAST AND THE HIGH
BROADENS TO THE WEST. NORTHEASTERLY LOW LEVEL FLOW LOOKS TO SET UP
NEXT WEEKEND WITH THE MAIN TRACK OF LOW PRESSURE SYSTEMS POSITIONED
SOUTH OF THE LAKE.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
ILZ022 UNTIL 11 AM MONDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002 UNTIL 11 AM MONDAY.
LM...GALE WARNING...LMZ080-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ872-LMZ874-LMZ876-
LMZ878...10 PM MONDAY TO 9 PM TUESDAY.
GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1048 AM CDT MON MAR 18 2013
.DISCUSSION...
529 AM CDT
A WINTER ADVISORY HAS BEEN ISSUED FOR A PORTION OF NORTHERN
ILLINOIS AND NORTHWEST INDIANA THROUGH 11 AM...WITH SLEET AND
FREEZING RAIN THE MAIN CONCERNS.
LATEST RADAR IMAGERY CONTINUES TO SHOW PRECIP SHIELD BLOSSOMING
EARLY THIS MORNING AS LARGE SCALE FORCING INCREASES ACROSS THE
AREA. THIS FORCING COINCIDING WITH A THERMAL PROFILE SUPPORTIVE OF
A WINTRY MIX...HAS RESULTED IN WIDESPREAD SLEET AND FREEZING RAIN
BEING REPORTED. AT THE OFFICE HERE IN ROMEOVILLE...MORE SLEET
ACCUMULATION HAS BEEN NOTICED OVER THE LAST HOUR. THIS SLEET
ACCUMULATION AS WELL AS THE FURTHER BLOSSOMING OF THE PRECIP
SHIELD IS WHAT HAS PROMPTED THE ADVISORY. ALTHOUGH ANY SNOW/SLEET
ACCUMULATION WILL REMAIN RATHER MINOR AROUND AN INCH...ITS ONCE
AGAIN THE SLEET ACCUMULATION COINCIDING WITH LIGHT FREEZING RAIN
WHICH IS THE MAIN CONCERN...CONCERNS OF SLIPPERY CONDITIONS FOR
THE MORNING COMMUTE. STILL EXPECT FURTHER SNOW ACCUMULATION LATER
THIS MORNING INTO THE AFTERNOON...BUT WITH SNOW THE LIKELY PRECIP
TYPE.
RODRIGUEZ
//PREV DISCUSSION...
406 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH A
WINTRY MIX OF PRECIP ONGOING...AND THEN CONTINUING THROUGH THE
REMAINDER OF THE DAY WITH SNOW LIKELY ACROSS THE NORTHERN THIRD OF
THE CWA WHILE A RAIN/SNOW MIX FURTHER SOUTH TOWARDS THE I80
CORRIDOR...AND THEN ALL RAIN ACROSS THE SOUTHERN TIER OF COUNTIES.
LATEST RADAR IMAGERY IS DEPICTING AN AREA OF PRECIPITATION
SPREADING NORTH ACROSS PARTS OF NORTHEAST ILLINOIS AND NORTHWEST
INDIANA AS AN MID LEVEL WAVE TRACKS NORTHEAST ACROSS THE REGION.
LATEST REPORTS CONTINUE TO SUPPORT A WINTRY MIX THAT HAS BEEN
ANTICIPATED WITH SNOW OR SLEET FALLING ON THE NORTHERN FRINGE OF
THIS PRECIP SHIELD FROM STREATOR IN ILLINOIS EAST TO RENSSELAER IN
INDIANA...WHILE A RAIN SNOW MIX HAD BEEN REPORTED JUST SOUTH OF
THIS LINE. OVER THE NEXT COUPLE OF HOURS THIS TREND WILL LIKELY
CONTINUE AS THIS WINTRY MIX MOVES NORTH TOWARD THE CHICAGO METRO
AREA. ALTHOUGH WEAK...LATEST RAP ANALYSIS IS SHOWING SOME WAA
AIDING IN THIS DEVELOPMENT AND EXPECT THIS WEAK WAA TO FURTHER AID
THIS MORNING UNTIL MORE LARGE SCALE SUPPORT ARRIVES FROM THE WEST.
EXPECT SNOW OR SLEET WITH ONLY MINOR ACCUMULATIONS INITIALLY EARLY
THIS MORNING ALONG AND NORTH OF INTERSTATE 80...JUST SOUTH OF THE
INTERSTATE 80 CORRIDOR A RAIN SNOW MIX WILL BE LIKELY CONTINUE.
SURFACE TEMPS THIS MORNING HAVE BEEN SLOWLY FALLING WITH CURRENT
TEMPS AT OR JUST BELOW FREEZING ACROSS MUCH OF THE CWA. IN THOSE
AREAS WHERE LIGHT RAIN DOES OCCUR...THESE SURFACE TEMPERATURES
WILL SUPPORT THE POTENTIAL FOR BRIDGES AND ELEVATED ROADWAYS TO
ACCUMULATE A THIN LAYER OF ICING. ALTHOUGH THIS WINTRY MIX HAD
BEEN FALLING OVER THE LAST COUPLE OF HOURS...REPORTS HAD NOT
INDICATED ANY WIDESPREAD SLIPPERY CONDITIONS BUT WITH ROADS
REMAINING ONLY WET AT THAT TIME. WOULD SUSPECT THAT SLIPPERY
CONDITIONS ARE CURRENTLY DEVELOPING AND COULD POSSIBLY CONTINUE TO
DEVELOP OVER THE NEXT COUPLE OF HOURS. OF GREATEST CONCERN AT THIS
TIME FOR THESE SLIPPERY CONDITIONS WOULD BE THE I80 CORRIDOR WHERE
CURRENTLY THE STRONGEST RETURNS ON RADAR ARE LOCATED AS WELL AS
WITH SURFACE TEMPS JUST BELOW FREEZING. HAVE REISSUED AN SPS AT
THIS TIME FOR THOSE AREAS...WHILE NOT ISSUING ANY OTHER HEADLINES
AT THIS TIME. FORCING FOR THIS CURRENT PRECIP ACROSS THE CWA
SHOULD EXIT OVER THE NEXT COUPLE OF HOURS...WITH LATEST SHORT TERM
GUIDANCE SHOWING A DIMINISHING TREND WITHIN THE OVERALL EXTENT OF
THIS PRECIP. RESIDENCE TIME FOR ANY FURTHER LINGERING PRECIP IN
THESE AREAS SHOULD BE LIMITED THIS MORNING...AS THIS PRECIP AXIS
SLOWLY LIFTS NORTH. ALTHOUGH A DIMINISHING TREND HERE IN THE NEAR
TERM IS LIKELY...ONCE AGAIN STILL ANTICIPATE A NORTHWARD PUSH OF
THIS PRECIP.
LARGE SCALE FORCING FOR ASCENT WILL INCREASE THROUGH MID MORNING
AS THE CURRENT UPPER LEVEL TROUGH JUST TO THE WEST PUSHES EAST.
THIS IS ALREADY BEGINNING TO OCCUR OVER AREAS IN EASTERN IOWA
WHERE LIGHT RETURNS ARE BEGINNING TO SHOW UP ON RADAR. EXPECT
FURTHER DEVELOPMENT THROUGH MID TO LATE MORNING WITH A MIXED BAG
OF PRECIPITATION STILL LIKELY. ALTHOUGH...LATEST GUIDANCE IS
SHOWING THAT COLDER AIR WILL BE IN PLACE FURTHER SOUTH ACROSS THE
CWA THAN PREVIOUSLY ANTICIPATED WITH THE NUDGE OF WARMER AIR ALOFT
NOT AS PRONOUNCED FOR THIS MORNING OR MOST OF THE DAY...WITH
LATEST AMDAR SOUNDINGS SUPPORTED THESE THERMAL PROFILES. WITH THAT
IN MIND...HAVE SNOW OR SLEET POSSIBLE THROUGH MID MORNING FOR THE
NORTHERN HALF OF THE CWA ACROSS NORTH CENTRAL AND NORTHEAST
ILLINOIS WITH MORE LIQUID TYPE PRECIP EXPECTED FURTHER SOUTH.
SURFACE TEMPS WILL BE RISING THROUGH MID MORNING WITH ANY FURTHER
THREAT OF FREEZING RAIN IN THE CURRENT LOCATIONS BECOMING LESS
LIKELY. AS THIS UPPER LEVEL TROUGH SWINGS ACROSS THIS SNOW/SLEET
AND THEN SNOW THROUGH MID DAY AND EARLY AFTERNOON...DO THINK THERE
WILL BE SOME MINOR ACCUMULATIONS FOR AREAS ALONG AND NORTH OF THE
INTERSTATE 88 CORRIDOR INCLUDING THE WEST/NORTHWEST/NORTHERN
SUBURBS OF CHICAGO. ONE TO TWO INCHES WILL BE POSSIBLE NEAR THE
WISCONSIN BORDER WITH THREE INCHES AN OUTSIDE POSSIBILITY FOR
ISOLATED LOCATIONS...AND AROUND AN INCH FURTHER SOUTH. A TREND
TOWARDS MORE DRIZZLE WILL BE POSSIBLE BY MID AFTERNOON BUT AS THIS
OCCURS...MUCH COLDER AIR WILL BE SWEEPING THROUGH THE CWA. THIS
COULD HELP FOR FURTHER CRYSTALS TO DEVELOP AND HELP LIGHT SNOW TO
LINGER AROUND INTO THE AFTERNOON AND EARLY EVENING BUT WITH LITTLE
OR NO ADDITIONAL ACCUMULATION LIKELY. COLDER TEMPS STILL ON PAR
FOR THIS WEEK...STARTING OFF TONIGHT WITH LOW TO MID TEENS
POSSIBLE ACROSS MUCH OF THE CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* DURATION OF MIXED PRECIP AND TIMING OF TYPE CHANGES.
* VSBY LESS THAN 3SM AS SURFACE CONDITIONS SATURATE WITH ONGOING
LIGHT PRECIPITATION.
* IFR CIGS...WITH IMPROVEMENT TO MVFR LATE THIS AFTERNOON.
* EAST WINDS EASING IN SPEED AND TURNING CLOCKWISE TO BECOME
SOUTHWEST THIS AFTERNOON...FURTHER SHIFT TO WEST LATE AFTERNOON
WITH GUSTS INCREASING TO 30-35 KT THIS EVENING.
* ADDITIONAL SNOW SHOWERS POSSIBLE THIS EVENING.
BMD
//DISCUSSION...UPDATED 12Z...
BAND OF MIXED PRECIP CONTINUE TO LIFT NORTHWARD ACROSS THE
TERMINALS AND HAS BEEN EXPANDING ON ITS SOUTHERN FLANK. HAVE RUN
THE GAMUT OF PRECIP TYPES LAST FEW HOURS BUT EXPECT THAT MDW/GYY
WILL CONTINUE TO HAVE THE BEST CHANCE FOR LIQUID PRECIP /RAIN OR
FREEZING RAIN/ TO MIX IN FOR THE NEXT FEW HOURS WHILE ORD/DPA LOOK
TO REMAIN A COMBINATION OF SNOW AND SLEET...THOUGH CANNOT
COMPLETELY RULE OUT SOME LIQUID FALLING AT THESE SITES FOR A SHORT
TIME. THE WARMER PUNCH CAUSING THE MIXED PRECIP WILL SHIFT EASTWARD
THROUGH LATE MORNING WHICH SHOULD ALLOW MAINLY SNOW TO TAKE
OVER...BUT SURFACE TEMPS WILL BE WARMING...ESPECIALLY SOUTH...SO
SOME RAIN/SNOW COULD OCCUR THROUGH MIDDAY. RFD IS EXPECTED TO
REMAIN MAINLY SNOW THOUGH SOME PELLETS COULD MIX IN. A
TROUGH/FRONT WILL APPROACH FROM THE WEST THIS AFTERNOON AND A BAND
OF SNOW CURRENTLY ACROSS CENTRAL IOWA WILL CROSS THE TERMINALS
TOWARD MIDDAY. THIS MAY START TO MOVE MORE TO THE NORTHEAST SO GYY
MAY SEE THE LEAST IMPACT IN TERMS OF VSBY REDUCTION IN LIGHT SNOW
AS THIS OCCURS. OTHERWISE WILL WORK A PERIOD OF LOWER VSBY ACROSS
THE TERMINALS TO ACCOUNT FOR THIS BAND. RFD SHOULD SEE THE
GREATEST ACCUMULATION WITH AN INCH OR TWO OF SNOW POSSIBLE BY MID
AFTERNOON. ORD/DPA MAY SEE A FEW TENTHS OF SLEET/SNOW ACCUM THIS
MORNING...WITH A FEW MORE TENTHS POSSIBLE WITH THE SECOND BAND
INTO EARLY AFTERNOON...BUT TEMPS ABOVE FREEZING MAY PRECLUDE THIS.
ONCE THE BAND PASSES WINDS WILL TURN WESTERLY AND THEN BECOME VERY
GUSTY LATE THIS AFTERNOON/EARLY THIS EVENING...WITH GUSTS OF 30-35
KT EXPECTED. THIS SHOULD ALSO HELP TO BRING IFR CIGS UP TO MVFR
LATE THIS AFTERNOON BUT IT IS NOT CLEAR HOW MUCH IMPROVEMENT WILL
OCCUR PRIOR TO SUNSET. COLDER AIR WILL BE SPREADING IN SO THERE
MAY BE RE-DEVELOPMENT OF SNOW SHOWERS THIS EVENING...WHICH IF THEY
CAN DEVELOP...COULD BRING SHORT PERIODS OF REDUCED VSBY.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* LOW CONFIDENCE ON SFC TEMPS AND WHEN FZ COMPONENT OF -RA/DZ WILL
END.
* HIGH CONFIDENCE IN IFR CIGS.
* HIGH CONFIDENCE IN WIND TRENDS.
* LOW CONFIDENCE IN ADDITIONAL SNOW SHOWERS DEVELOPING THIS
EVENING.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH SUNDAY...MAINLY VFR...GUSTY WEST WINDS
TUESDAY NIGHT AND WEDNESDAY.
MDB
&&
.MARINE...
323 AM CDT
LOW PRESSURE CONTINUES TO MOVE EAST ACROSS THE EASTERN DAKOTAS AND
WILL REACH EASTERN LAKE SUPERIOR TUESDAY MORNING. ANOTHER LOW IS
ALSO MOVING UP THE OHIO RIVER VALLEY AND WILL MERGE WITH THE MAIN
LOW TUESDAY. EAST TO SOUTHEAST WINDS CONTINUE ACROSS LAKE MICHIGAN
THIS MORNING WITH THE STRONGEST SPEEDS ACROSS THE CENTRAL SECTION OF
THE LAKE. THE PRESSURE GRADIENT WILL WEAKEN THROUGH THE MORNING
ALLOWING SPEEDS TO EASE UP WITH WINDS THEN SHIFTING TO THE WEST AND
SOUTHWEST THROUGH THE AFTERNOON. THE WEAKENING WINDS AND SHIFT IN
DIRECTION SHOULD HELP TO KNOCK WAVES DOWN SO WILL PLAN ON LETTING
THE SMALL CRAFT ADVISORY FOR THE ILLINOIS NEARSHORE WATERS EXPIRE AT
18Z. WEST WINDS WILL RAMP UP TO 35-40 KT GALES ACROSS THE SOUTHERN
TWO-THIRDS OF THE LAKE THIS EVENING WITH THE FAR NORTHERN SECTION
LIKELY BEING HELD TO AROUND 30 KT THANKS TO THE NEARBY PASSAGE OF
THE SURFACE LOW TONIGHT. HAVE UPGRADED THE GALE WATCH TO A GALE
WARNING FOR THE OPEN WATERS. ISSUED A GALE WATCH FOR THE ILLINOIS
NEARSHORE WATERS AS WELL AS THE INDIANA WATERS FROM CALUMET HARBOR
TO GARY...WITH SOME UNCERTAINTY ON WHETHER GALE FORCE WILL BE ABLE
TO BE REACHED GIVEN THE OFFSHORE WIND COMPONENT. HOWEVER...DID
UPGRADE AREAS FROM GARY EAST TO A GALE WARNING GIVEN THEIR BETTER
ONSHORE EXPOSURE. OTHERWISE...TEMPERATURES WILL FALL AS MUCH COLDER
AIR BUILDS IN WHICH WILL SET THE STAGE FOR FREEZING SPRAY. THE LOW
WILL BE SLOW TO DEPART TO THE EAST WHILE HIGH PRESSURE SPREADS INTO
THE NORTHERN PLAINS INTO TUESDAY NIGHT. THIS WILL KEEP WINDS STRONG
INTO TUESDAY EVENING BUT SPEEDS LOOK TO FALL JUST BELOW GALE FORCE
TUESDAY EVENING OR TUESDAY NIGHT...BUT SOME GALE FORCE GUSTS MAY
CONTINUE EVEN THROUGH WEDNESDAY. WILL KEEP 30 KT IN THE FORECAST FOR
THIS TIME FRAME FOR NOW THOUGH. THE PRESSURE GRADIENT WILL GRADUALLY
WEAKEN THROUGH THURSDAY AS THE LOW FILLS TO THE EAST AND THE HIGH
BROADENS TO THE WEST. NORTHEASTERLY LOW LEVEL FLOW LOOKS TO SET UP
NEXT WEEKEND WITH THE MAIN TRACK OF LOW PRESSURE SYSTEMS POSITIONED
SOUTH OF THE LAKE.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
ILZ022 UNTIL 11 AM MONDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002 UNTIL 11 AM MONDAY.
LM...GALE WARNING...LMZ080-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ872-LMZ874-LMZ876-
LMZ878...10 PM MONDAY TO 9 PM TUESDAY.
GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
911 AM CDT MON MAR 18 2013
.DISCUSSION...
529 AM CDT
A WINTER ADVISORY HAS BEEN ISSUED FOR A PORTION OF NORTHERN
ILLINOIS AND NORTHWEST INDIANA THROUGH 11 AM...WITH SLEET AND
FREEZING RAIN THE MAIN CONCERNS.
LATEST RADAR IMAGERY CONTINUES TO SHOW PRECIP SHIELD BLOSSOMING
EARLY THIS MORNING AS LARGE SCALE FORCING INCREASES ACROSS THE
AREA. THIS FORCING COINCIDING WITH A THERMAL PROFILE SUPPORTIVE OF
A WINTRY MIX...HAS RESULTED IN WIDESPREAD SLEET AND FREEZING RAIN
BEING REPORTED. AT THE OFFICE HERE IN ROMEOVILLE...MORE SLEET
ACCUMULATION HAS BEEN NOTICED OVER THE LAST HOUR. THIS SLEET
ACCUMULATION AS WELL AS THE FURTHER BLOSSOMING OF THE PRECIP
SHIELD IS WHAT HAS PROMPTED THE ADVISORY. ALTHOUGH ANY SNOW/SLEET
ACCUMULATION WILL REMAIN RATHER MINOR AROUND AN INCH...ITS ONCE
AGAIN THE SLEET ACCUMULATION COINCIDING WITH LIGHT FREEZING RAIN
WHICH IS THE MAIN CONCERN...CONCERNS OF SLIPPERY CONDITIONS FOR
THE MORNING COMMUTE. STILL EXPECT FURTHER SNOW ACCUMULATION LATER
THIS MORNING INTO THE AFTERNOON...BUT WITH SNOW THE LIKELY PRECIP
TYPE.
RODRIGUEZ
//PREV DISCUSSION...
406 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH A
WINTRY MIX OF PRECIP ONGOING...AND THEN CONTINUING THROUGH THE
REMAINDER OF THE DAY WITH SNOW LIKELY ACROSS THE NORTHERN THIRD OF
THE CWA WHILE A RAIN/SNOW MIX FURTHER SOUTH TOWARDS THE I80
CORRIDOR...AND THEN ALL RAIN ACROSS THE SOUTHERN TIER OF COUNTIES.
LATEST RADAR IMAGERY IS DEPICTING AN AREA OF PRECIPITATION
SPREADING NORTH ACROSS PARTS OF NORTHEAST ILLINOIS AND NORTHWEST
INDIANA AS AN MID LEVEL WAVE TRACKS NORTHEAST ACROSS THE REGION.
LATEST REPORTS CONTINUE TO SUPPORT A WINTRY MIX THAT HAS BEEN
ANTICIPATED WITH SNOW OR SLEET FALLING ON THE NORTHERN FRINGE OF
THIS PRECIP SHIELD FROM STREATOR IN ILLINOIS EAST TO RENSSELAER IN
INDIANA...WHILE A RAIN SNOW MIX HAD BEEN REPORTED JUST SOUTH OF
THIS LINE. OVER THE NEXT COUPLE OF HOURS THIS TREND WILL LIKELY
CONTINUE AS THIS WINTRY MIX MOVES NORTH TOWARD THE CHICAGO METRO
AREA. ALTHOUGH WEAK...LATEST RAP ANALYSIS IS SHOWING SOME WAA
AIDING IN THIS DEVELOPMENT AND EXPECT THIS WEAK WAA TO FURTHER AID
THIS MORNING UNTIL MORE LARGE SCALE SUPPORT ARRIVES FROM THE WEST.
EXPECT SNOW OR SLEET WITH ONLY MINOR ACCUMULATIONS INITIALLY EARLY
THIS MORNING ALONG AND NORTH OF INTERSTATE 80...JUST SOUTH OF THE
INTERSTATE 80 CORRIDOR A RAIN SNOW MIX WILL BE LIKELY CONTINUE.
SURFACE TEMPS THIS MORNING HAVE BEEN SLOWLY FALLING WITH CURRENT
TEMPS AT OR JUST BELOW FREEZING ACROSS MUCH OF THE CWA. IN THOSE
AREAS WHERE LIGHT RAIN DOES OCCUR...THESE SURFACE TEMPERATURES
WILL SUPPORT THE POTENTIAL FOR BRIDGES AND ELEVATED ROADWAYS TO
ACCUMULATE A THIN LAYER OF ICING. ALTHOUGH THIS WINTRY MIX HAD
BEEN FALLING OVER THE LAST COUPLE OF HOURS...REPORTS HAD NOT
INDICATED ANY WIDESPREAD SLIPPERY CONDITIONS BUT WITH ROADS
REMAINING ONLY WET AT THAT TIME. WOULD SUSPECT THAT SLIPPERY
CONDITIONS ARE CURRENTLY DEVELOPING AND COULD POSSIBLY CONTINUE TO
DEVELOP OVER THE NEXT COUPLE OF HOURS. OF GREATEST CONCERN AT THIS
TIME FOR THESE SLIPPERY CONDITIONS WOULD BE THE I80 CORRIDOR WHERE
CURRENTLY THE STRONGEST RETURNS ON RADAR ARE LOCATED AS WELL AS
WITH SURFACE TEMPS JUST BELOW FREEZING. HAVE REISSUED AN SPS AT
THIS TIME FOR THOSE AREAS...WHILE NOT ISSUING ANY OTHER HEADLINES
AT THIS TIME. FORCING FOR THIS CURRENT PRECIP ACROSS THE CWA
SHOULD EXIT OVER THE NEXT COUPLE OF HOURS...WITH LATEST SHORT TERM
GUIDANCE SHOWING A DIMINISHING TREND WITHIN THE OVERALL EXTENT OF
THIS PRECIP. RESIDENCE TIME FOR ANY FURTHER LINGERING PRECIP IN
THESE AREAS SHOULD BE LIMITED THIS MORNING...AS THIS PRECIP AXIS
SLOWLY LIFTS NORTH. ALTHOUGH A DIMINISHING TREND HERE IN THE NEAR
TERM IS LIKELY...ONCE AGAIN STILL ANTICIPATE A NORTHWARD PUSH OF
THIS PRECIP.
LARGE SCALE FORCING FOR ASCENT WILL INCREASE THROUGH MID MORNING
AS THE CURRENT UPPER LEVEL TROUGH JUST TO THE WEST PUSHES EAST.
THIS IS ALREADY BEGINNING TO OCCUR OVER AREAS IN EASTERN IOWA
WHERE LIGHT RETURNS ARE BEGINNING TO SHOW UP ON RADAR. EXPECT
FURTHER DEVELOPMENT THROUGH MID TO LATE MORNING WITH A MIXED BAG
OF PRECIPITATION STILL LIKELY. ALTHOUGH...LATEST GUIDANCE IS
SHOWING THAT COLDER AIR WILL BE IN PLACE FURTHER SOUTH ACROSS THE
CWA THAN PREVIOUSLY ANTICIPATED WITH THE NUDGE OF WARMER AIR ALOFT
NOT AS PRONOUNCED FOR THIS MORNING OR MOST OF THE DAY...WITH
LATEST AMDAR SOUNDINGS SUPPORTED THESE THERMAL PROFILES. WITH THAT
IN MIND...HAVE SNOW OR SLEET POSSIBLE THROUGH MID MORNING FOR THE
NORTHERN HALF OF THE CWA ACROSS NORTH CENTRAL AND NORTHEAST
ILLINOIS WITH MORE LIQUID TYPE PRECIP EXPECTED FURTHER SOUTH.
SURFACE TEMPS WILL BE RISING THROUGH MID MORNING WITH ANY FURTHER
THREAT OF FREEZING RAIN IN THE CURRENT LOCATIONS BECOMING LESS
LIKELY. AS THIS UPPER LEVEL TROUGH SWINGS ACROSS THIS SNOW/SLEET
AND THEN SNOW THROUGH MID DAY AND EARLY AFTERNOON...DO THINK THERE
WILL BE SOME MINOR ACCUMULATIONS FOR AREAS ALONG AND NORTH OF THE
INTERSTATE 88 CORRIDOR INCLUDING THE WEST/NORTHWEST/NORTHERN
SUBURBS OF CHICAGO. ONE TO TWO INCHES WILL BE POSSIBLE NEAR THE
WISCONSIN BORDER WITH THREE INCHES AN OUTSIDE POSSIBILITY FOR
ISOLATED LOCATIONS...AND AROUND AN INCH FURTHER SOUTH. A TREND
TOWARDS MORE DRIZZLE WILL BE POSSIBLE BY MID AFTERNOON BUT AS THIS
OCCURS...MUCH COLDER AIR WILL BE SWEEPING THROUGH THE CWA. THIS
COULD HELP FOR FURTHER CRYSTALS TO DEVELOP AND HELP LIGHT SNOW TO
LINGER AROUND INTO THE AFTERNOON AND EARLY EVENING BUT WITH LITTLE
OR NO ADDITIONAL ACCUMULATION LIKELY. COLDER TEMPS STILL ON PAR
FOR THIS WEEK...STARTING OFF TONIGHT WITH LOW TO MID TEENS
POSSIBLE ACROSS MUCH OF THE CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* DURATION OF MIXED PRECIP AND TIMING OF TYPE CHANGES.
* MVFR CIGS LOWERING TO IFR...THEN EXPECTED TO IMPROVE TO MVFR
LATE THIS AFTERNOON.
* EAST WINDS EASING IN SPEED AND BECOMING SOUTHWEST THIS
AFTERNOON...FURTHER SHIFT TO WEST LATE AFTERNOON WITH GUSTS
INCREASING TO 30-35 KT THIS EVENING.
* ADDITIONAL SNOW SHOWERS POSSIBLE THIS EVENING.
BMD
//DISCUSSION...UPDATED 12Z...
BAND OF MIXED PRECIP CONTINUE TO LIFT NORTHWARD ACROSS THE
TERMINALS AND HAS BEEN EXPANDING ON ITS SOUTHERN FLANK. HAVE RUN
THE GAMUT OF PRECIP TYPES LAST FEW HOURS BUT EXPECT THAT MDW/GYY
WILL CONTINUE TO HAVE THE BEST CHANCE FOR LIQUID PRECIP /RAIN OR
FREEZING RAIN/ TO MIX IN FOR THE NEXT FEW HOURS WHILE ORD/DPA LOOK
TO REMAIN A COMBINATION OF SNOW AND SLEET...THOUGH CANNOT
COMPLETELY RULE OUT SOME LIQUID FALLING AT THESE SITES FOR A SHORT
TIME. THE WARMER PUNCH CAUSING THE MIXED PRECIP WILL SHIFT EASTWARD
THROUGH LATE MORNING WHICH SHOULD ALLOW MAINLY SNOW TO TAKE
OVER...BUT SURFACE TEMPS WILL BE WARMING...ESPECIALLY SOUTH...SO
SOME RAIN/SNOW COULD OCCUR THROUGH MIDDAY. RFD IS EXPECTED TO
REMAIN MAINLY SNOW THOUGH SOME PELLETS COULD MIX IN. A
TROUGH/FRONT WILL APPROACH FROM THE WEST THIS AFTERNOON AND A BAND
OF SNOW CURRENTLY ACROSS CENTRAL IOWA WILL CROSS THE TERMINALS
TOWARD MIDDAY. THIS MAY START TO MOVE MORE TO THE NORTHEAST SO GYY
MAY SEE THE LEAST IMPACT IN TERMS OF VSBY REDUCTION IN LIGHT SNOW
AS THIS OCCURS. OTHERWISE WILL WORK A PERIOD OF LOWER VSBY ACROSS
THE TERMINALS TO ACCOUNT FOR THIS BAND. RFD SHOULD SEE THE
GREATEST ACCUMULATION WITH AN INCH OR TWO OF SNOW POSSIBLE BY MID
AFTERNOON. ORD/DPA MAY SEE A FEW TENTHS OF SLEET/SNOW ACCUM THIS
MORNING...WITH A FEW MORE TENTHS POSSIBLE WITH THE SECOND BAND
INTO EARLY AFTERNOON...BUT TEMPS ABOVE FREEZING MAY PRECLUDE THIS.
ONCE THE BAND PASSES WINDS WILL TURN WESTERLY AND THEN BECOME VERY
GUSTY LATE THIS AFTERNOON/EARLY THIS EVENING...WITH GUSTS OF 30-35
KT EXPECTED. THIS SHOULD ALSO HELP TO BRING IFR CIGS UP TO MVFR
LATE THIS AFTERNOON BUT IT IS NOT CLEAR HOW MUCH IMPROVEMENT WILL
OCCUR PRIOR TO SUNSET. COLDER AIR WILL BE SPREADING IN SO THERE
MAY BE RE-DEVELOPMENT OF SNOW SHOWERS THIS EVENING...WHICH IF THEY
CAN DEVELOP...COULD BRING SHORT PERIODS OF REDUCED VSBY.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN PRECIP TRANSITIONING TO DRIZZLE...LOW
CONFIDENCE ON SFC TEMPS AND WHEN FZ COMPONENT WILL END.
* HIGH CONFIDENCE IN CIGS LOWERING TO IFR...MEDIUM CONFIDENCE
IN TIMING OF ARRIVAL.
* HIGH CONFIDENCE IN WIND TRENDS.
* MEDIUM CONFIDENCE IN ADDITIONAL SNOW SHOWERS DEVELOPING THIS
EVENING.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH SUNDAY...MAINLY VFR...GUSTY WEST WINDS
TUESDAY NIGHT AND WEDNESDAY.
MDB
&&
.MARINE...
323 AM CDT
LOW PRESSURE CONTINUES TO MOVE EAST ACROSS THE EASTERN DAKOTAS AND
WILL REACH EASTERN LAKE SUPERIOR TUESDAY MORNING. ANOTHER LOW IS
ALSO MOVING UP THE OHIO RIVER VALLEY AND WILL MERGE WITH THE MAIN
LOW TUESDAY. EAST TO SOUTHEAST WINDS CONTINUE ACROSS LAKE MICHIGAN
THIS MORNING WITH THE STRONGEST SPEEDS ACROSS THE CENTRAL SECTION OF
THE LAKE. THE PRESSURE GRADIENT WILL WEAKEN THROUGH THE MORNING
ALLOWING SPEEDS TO EASE UP WITH WINDS THEN SHIFTING TO THE WEST AND
SOUTHWEST THROUGH THE AFTERNOON. THE WEAKENING WINDS AND SHIFT IN
DIRECTION SHOULD HELP TO KNOCK WAVES DOWN SO WILL PLAN ON LETTING
THE SMALL CRAFT ADVISORY FOR THE ILLINOIS NEARSHORE WATERS EXPIRE AT
18Z. WEST WINDS WILL RAMP UP TO 35-40 KT GALES ACROSS THE SOUTHERN
TWO-THIRDS OF THE LAKE THIS EVENING WITH THE FAR NORTHERN SECTION
LIKELY BEING HELD TO AROUND 30 KT THANKS TO THE NEARBY PASSAGE OF
THE SURFACE LOW TONIGHT. HAVE UPGRADED THE GALE WATCH TO A GALE
WARNING FOR THE OPEN WATERS. ISSUED A GALE WATCH FOR THE ILLINOIS
NEARSHORE WATERS AS WELL AS THE INDIANA WATERS FROM CALUMET HARBOR
TO GARY...WITH SOME UNCERTAINTY ON WHETHER GALE FORCE WILL BE ABLE
TO BE REACHED GIVEN THE OFFSHORE WIND COMPONENT. HOWEVER...DID
UPGRADE AREAS FROM GARY EAST TO A GALE WARNING GIVEN THEIR BETTER
ONSHORE EXPOSURE. OTHERWISE...TEMPERATURES WILL FALL AS MUCH COLDER
AIR BUILDS IN WHICH WILL SET THE STAGE FOR FREEZING SPRAY. THE LOW
WILL BE SLOW TO DEPART TO THE EAST WHILE HIGH PRESSURE SPREADS INTO
THE NORTHERN PLAINS INTO TUESDAY NIGHT. THIS WILL KEEP WINDS STRONG
INTO TUESDAY EVENING BUT SPEEDS LOOK TO FALL JUST BELOW GALE FORCE
TUESDAY EVENING OR TUESDAY NIGHT...BUT SOME GALE FORCE GUSTS MAY
CONTINUE EVEN THROUGH WEDNESDAY. WILL KEEP 30 KT IN THE FORECAST FOR
THIS TIME FRAME FOR NOW THOUGH. THE PRESSURE GRADIENT WILL GRADUALLY
WEAKEN THROUGH THURSDAY AS THE LOW FILLS TO THE EAST AND THE HIGH
BROADENS TO THE WEST. NORTHEASTERLY LOW LEVEL FLOW LOOKS TO SET UP
NEXT WEEKEND WITH THE MAIN TRACK OF LOW PRESSURE SYSTEMS POSITIONED
SOUTH OF THE LAKE.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
ILZ022 UNTIL 11 AM MONDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002 UNTIL 11 AM MONDAY.
LM...GALE WARNING...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
GALE WATCH...LMZ740-LMZ741-LMZ742-LMZ743...10 PM MONDAY TO 9 PM
TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
650 AM CDT MON MAR 18 2013
.DISCUSSION...
529 AM CDT
A WINTER ADVISORY HAS BEEN ISSUED FOR A PORTION OF NORTHERN
ILLINOIS AND NORTHWEST INDIANA THROUGH 11 AM...WITH SLEET AND
FREEZING RAIN THE MAIN CONCERNS.
LATEST RADAR IMAGERY CONTINUES TO SHOW PRECIP SHIELD BLOSSOMING
EARLY THIS MORNING AS LARGE SCALE FORCING INCREASES ACROSS THE
AREA. THIS FORCING COINCIDING WITH A THERMAL PROFILE SUPPORTIVE OF
A WINTRY MIX...HAS RESULTED IN WIDESPREAD SLEET AND FREEZING RAIN
BEING REPORTED. AT THE OFFICE HERE IN ROMEOVILLE...MORE SLEET
ACCUMULATION HAS BEEN NOTICED OVER THE LAST HOUR. THIS SLEET
ACCUMULATION AS WELL AS THE FURTHER BLOSSOMING OF THE PRECIP
SHIELD IS WHAT HAS PROMPTED THE ADVISORY. ALTHOUGH ANY SNOW/SLEET
ACCUMULATION WILL REMAIN RATHER MINOR AROUND AN INCH...ITS ONCE
AGAIN THE SLEET ACCUMULATION COINCIDING WITH LIGHT FREEZING RAIN
WHICH IS THE MAIN CONCERN...CONCERNS OF SLIPPERY CONDITIONS FOR
THE MORNING COMMUTE. STILL EXPECT FURTHER SNOW ACCUMULATION LATER
THIS MORNING INTO THE AFTERNOON...BUT WITH SNOW THE LIKELY PRECIP
TYPE.
RODRIGUEZ
//PREV DISCUSSION...
406 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH A
WINTRY MIX OF PRECIP ONGOING...AND THEN CONTINUING THROUGH THE
REMAINDER OF THE DAY WITH SNOW LIKELY ACROSS THE NORTHERN THIRD OF
THE CWA WHILE A RAIN/SNOW MIX FURTHER SOUTH TOWARDS THE I80
CORRIDOR...AND THEN ALL RAIN ACROSS THE SOUTHERN TIER OF COUNTIES.
LATEST RADAR IMAGERY IS DEPICTING AN AREA OF PRECIPITATION
SPREADING NORTH ACROSS PARTS OF NORTHEAST ILLINOIS AND NORTHWEST
INDIANA AS AN MID LEVEL WAVE TRACKS NORTHEAST ACROSS THE REGION.
LATEST REPORTS CONTINUE TO SUPPORT A WINTRY MIX THAT HAS BEEN
ANTICIPATED WITH SNOW OR SLEET FALLING ON THE NORTHERN FRINGE OF
THIS PRECIP SHIELD FROM STREATOR IN ILLINOIS EAST TO RENSSELAER IN
INDIANA...WHILE A RAIN SNOW MIX HAD BEEN REPORTED JUST SOUTH OF
THIS LINE. OVER THE NEXT COUPLE OF HOURS THIS TREND WILL LIKELY
CONTINUE AS THIS WINTRY MIX MOVES NORTH TOWARD THE CHICAGO METRO
AREA. ALTHOUGH WEAK...LATEST RAP ANALYSIS IS SHOWING SOME WAA
AIDING IN THIS DEVELOPMENT AND EXPECT THIS WEAK WAA TO FURTHER AID
THIS MORNING UNTIL MORE LARGE SCALE SUPPORT ARRIVES FROM THE WEST.
EXPECT SNOW OR SLEET WITH ONLY MINOR ACCUMULATIONS INITIALLY EARLY
THIS MORNING ALONG AND NORTH OF INTERSTATE 80...JUST SOUTH OF THE
INTERSTATE 80 CORRIDOR A RAIN SNOW MIX WILL BE LIKELY CONTINUE.
SURFACE TEMPS THIS MORNING HAVE BEEN SLOWLY FALLING WITH CURRENT
TEMPS AT OR JUST BELOW FREEZING ACROSS MUCH OF THE CWA. IN THOSE
AREAS WHERE LIGHT RAIN DOES OCCUR...THESE SURFACE TEMPERATURES
WILL SUPPORT THE POTENTIAL FOR BRIDGES AND ELEVATED ROADWAYS TO
ACCUMULATE A THIN LAYER OF ICING. ALTHOUGH THIS WINTRY MIX HAD
BEEN FALLING OVER THE LAST COUPLE OF HOURS...REPORTS HAD NOT
INDICATED ANY WIDESPREAD SLIPPERY CONDITIONS BUT WITH ROADS
REMAINING ONLY WET AT THAT TIME. WOULD SUSPECT THAT SLIPPERY
CONDITIONS ARE CURRENTLY DEVELOPING AND COULD POSSIBLY CONTINUE TO
DEVELOP OVER THE NEXT COUPLE OF HOURS. OF GREATEST CONCERN AT THIS
TIME FOR THESE SLIPPERY CONDITIONS WOULD BE THE I80 CORRIDOR WHERE
CURRENTLY THE STRONGEST RETURNS ON RADAR ARE LOCATED AS WELL AS
WITH SURFACE TEMPS JUST BELOW FREEZING. HAVE REISSUED AN SPS AT
THIS TIME FOR THOSE AREAS...WHILE NOT ISSUING ANY OTHER HEADLINES
AT THIS TIME. FORCING FOR THIS CURRENT PRECIP ACROSS THE CWA
SHOULD EXIT OVER THE NEXT COUPLE OF HOURS...WITH LATEST SHORT TERM
GUIDANCE SHOWING A DIMINISHING TREND WITHIN THE OVERALL EXTENT OF
THIS PRECIP. RESIDENCE TIME FOR ANY FURTHER LINGERING PRECIP IN
THESE AREAS SHOULD BE LIMITED THIS MORNING...AS THIS PRECIP AXIS
SLOWLY LIFTS NORTH. ALTHOUGH A DIMINISHING TREND HERE IN THE NEAR
TERM IS LIKELY...ONCE AGAIN STILL ANTICIPATE A NORTHWARD PUSH OF
THIS PRECIP.
LARGE SCALE FORCING FOR ASCENT WILL INCREASE THROUGH MID MORNING
AS THE CURRENT UPPER LEVEL TROUGH JUST TO THE WEST PUSHES EAST.
THIS IS ALREADY BEGINNING TO OCCUR OVER AREAS IN EASTERN IOWA
WHERE LIGHT RETURNS ARE BEGINNING TO SHOW UP ON RADAR. EXPECT
FURTHER DEVELOPMENT THROUGH MID TO LATE MORNING WITH A MIXED BAG
OF PRECIPITATION STILL LIKELY. ALTHOUGH...LATEST GUIDANCE IS
SHOWING THAT COLDER AIR WILL BE IN PLACE FURTHER SOUTH ACROSS THE
CWA THAN PREVIOUSLY ANTICIPATED WITH THE NUDGE OF WARMER AIR ALOFT
NOT AS PRONOUNCED FOR THIS MORNING OR MOST OF THE DAY...WITH
LATEST AMDAR SOUNDINGS SUPPORTED THESE THERMAL PROFILES. WITH THAT
IN MIND...HAVE SNOW OR SLEET POSSIBLE THROUGH MID MORNING FOR THE
NORTHERN HALF OF THE CWA ACROSS NORTH CENTRAL AND NORTHEAST
ILLINOIS WITH MORE LIQUID TYPE PRECIP EXPECTED FURTHER SOUTH.
SURFACE TEMPS WILL BE RISING THROUGH MID MORNING WITH ANY FURTHER
THREAT OF FREEZING RAIN IN THE CURRENT LOCATIONS BECOMING LESS
LIKELY. AS THIS UPPER LEVEL TROUGH SWINGS ACROSS THIS SNOW/SLEET
AND THEN SNOW THROUGH MID DAY AND EARLY AFTERNOON...DO THINK THERE
WILL BE SOME MINOR ACCUMULATIONS FOR AREAS ALONG AND NORTH OF THE
INTERSTATE 88 CORRIDOR INCLUDING THE WEST/NORTHWEST/NORTHERN
SUBURBS OF CHICAGO. ONE TO TWO INCHES WILL BE POSSIBLE NEAR THE
WISCONSIN BORDER WITH THREE INCHES AN OUTSIDE POSSIBILITY FOR
ISOLATED LOCATIONS...AND AROUND AN INCH FURTHER SOUTH. A TREND
TOWARDS MORE DRIZZLE WILL BE POSSIBLE BY MID AFTERNOON BUT AS THIS
OCCURS...MUCH COLDER AIR WILL BE SWEEPING THROUGH THE CWA. THIS
COULD HELP FOR FURTHER CRYSTALS TO DEVELOP AND HELP LIGHT SNOW TO
LINGER AROUND INTO THE AFTERNOON AND EARLY EVENING BUT WITH LITTLE
OR NO ADDITIONAL ACCUMULATION LIKELY. COLDER TEMPS STILL ON PAR
FOR THIS WEEK...STARTING OFF TONIGHT WITH LOW TO MID TEENS
POSSIBLE ACROSS MUCH OF THE CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* DURATION OF MIXED PRECIP AND TIMING OF TYPE CHANGES.
* MVFR CIGS LOWERING TO IFR...THEN EXPECTED TO IMPROVE TO MVFR
LATE THIS AFTERNOON.
* EAST WINDS EASING IN SPEED AND BECOMING SOUTHWEST THIS
AFTERNOON...FURTHER SHIFT TO WEST LATE AFTERNOON WITH GUSTS
INCREASING TO 30-35 KT THIS EVENING.
* ADDITIONAL SNOW SHOWERS POSSIBLE THIS EVENING.
MDB
//DISCUSSION...UPDATED 12Z...
BAND OF MIXED PRECIP CONTINUE TO LIFT NORTHWARD ACROSS THE
TERMINALS AND HAS BEEN EXPANDING ON ITS SOUTHERN FLANK. HAVE RUN
THE GAMUT OF PRECIP TYPES LAST FEW HOURS BUT EXPECT THAT MDW/GYY
WILL CONTINUE TO HAVE THE BEST CHANCE FOR LIQUID PRECIP /RAIN OR
FREEZING RAIN/ TO MIX IN FOR THE NEXT FEW HOURS WHILE ORD/DPA LOOK
TO REMAIN A COMBINATION OF SNOW AND SLEET...THOUGH CANNOT
COMPLETELY RULE OUT SOME LIQUID FALLING AT THESE SITES FOR A SHORT
TIME. THE WARMER PUNCH CAUSING THE MIXED PRECIP WILL SHIFT EASTWARD
THROUGH LATE MORNING WHICH SHOULD ALLOW MAINLY SNOW TO TAKE
OVER...BUT SURFACE TEMPS WILL BE WARMING...ESPECIALLY SOUTH...SO
SOME RAIN/SNOW COULD OCCUR THROUGH MIDDAY. RFD IS EXPECTED TO
REMAIN MAINLY SNOW THOUGH SOME PELLETS COULD MIX IN. A
TROUGH/FRONT WILL APPROACH FROM THE WEST THIS AFTERNOON AND A BAND
OF SNOW CURRENTLY ACROSS CENTRAL IOWA WILL CROSS THE TERMINALS
TOWARD MIDDAY. THIS MAY START TO MOVE MORE TO THE NORTHEAST SO GYY
MAY SEE THE LEAST IMPACT IN TERMS OF VSBY REDUCTION IN LIGHT SNOW
AS THIS OCCURS. OTHERWISE WILL WORK A PERIOD OF LOWER VSBY ACROSS
THE TERMINALS TO ACCOUNT FOR THIS BAND. RFD SHOULD SEE THE
GREATEST ACCUMULATION WITH AN INCH OR TWO OF SNOW POSSIBLE BY MID
AFTERNOON. ORD/DPA MAY SEE A FEW TENTHS OF SLEET/SNOW ACCUM THIS
MORNING...WITH A FEW MORE TENTHS POSSIBLE WITH THE SECOND BAND
INTO EARLY AFTERNOON...BUT TEMPS ABOVE FREEZING MAY PRECLUDE THIS.
ONCE THE BAND PASSES WINDS WILL TURN WESTERLY AND THEN BECOME VERY
GUSTY LATE THIS AFTERNOON/EARLY THIS EVENING...WITH GUSTS OF 30-35
KT EXPECTED. THIS SHOULD ALSO HELP TO BRING IFR CIGS UP TO MVFR
LATE THIS AFTERNOON BUT IT IS NOT CLEAR HOW MUCH IMPROVEMENT WILL
OCCUR PRIOR TO SUNSET. COLDER AIR WILL BE SPREADING IN SO THERE
MAY BE RE-DEVELOPMENT OF SNOW SHOWERS THIS EVENING...WHICH IF THEY
CAN DEVELOP...COULD BRING SHORT PERIODS OF REDUCED VSBY.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM CONFIDENCE IN MAINLY SLEET/SNOW CHANGING TO SNOW MID
MORNING AT ORD...WITH MAINLY RAIN/SNOW/SLEET AT MDW CHANGING TO
SNOW. MEDIUM CONFIDENCE IN A PERIOD OF STEADIER SNOW ARRIVING
CLOSER TO MIDDAY.
* HIGH CONFIDENCE IN CIGS LOWERING TO IFR...LOW-MEDIUM CONFIDENCE
IN TIMING OF ARRIVAL AND TIMING OF IMPROVEMENT.
* HIGH CONFIDENCE IN WIND TRENDS.
* MEDIUM CONFIDENCE IN ADDITIONAL SNOW SHOWERS DEVELOPING THIS
EVENING.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH SUNDAY...MAINLY VFR...GUSTY WEST WINDS
TUESDAY NIGHT AND WEDNESDAY.
MDB
&&
.MARINE...
323 AM CDT
LOW PRESSURE CONTINUES TO MOVE EAST ACROSS THE EASTERN DAKOTAS AND
WILL REACH EASTERN LAKE SUPERIOR TUESDAY MORNING. ANOTHER LOW IS
ALSO MOVING UP THE OHIO RIVER VALLEY AND WILL MERGE WITH THE MAIN
LOW TUESDAY. EAST TO SOUTHEAST WINDS CONTINUE ACROSS LAKE MICHIGAN
THIS MORNING WITH THE STRONGEST SPEEDS ACROSS THE CENTRAL SECTION OF
THE LAKE. THE PRESSURE GRADIENT WILL WEAKEN THROUGH THE MORNING
ALLOWING SPEEDS TO EASE UP WITH WINDS THEN SHIFTING TO THE WEST AND
SOUTHWEST THROUGH THE AFTERNOON. THE WEAKENING WINDS AND SHIFT IN
DIRECTION SHOULD HELP TO KNOCK WAVES DOWN SO WILL PLAN ON LETTING
THE SMALL CRAFT ADVISORY FOR THE ILLINOIS NEARSHORE WATERS EXPIRE AT
18Z. WEST WINDS WILL RAMP UP TO 35-40 KT GALES ACROSS THE SOUTHERN
TWO-THIRDS OF THE LAKE THIS EVENING WITH THE FAR NORTHERN SECTION
LIKELY BEING HELD TO AROUND 30 KT THANKS TO THE NEARBY PASSAGE OF
THE SURFACE LOW TONIGHT. HAVE UPGRADED THE GALE WATCH TO A GALE
WARNING FOR THE OPEN WATERS. ISSUED A GALE WATCH FOR THE ILLINOIS
NEARSHORE WATERS AS WELL AS THE INDIANA WATERS FROM CALUMET HARBOR
TO GARY...WITH SOME UNCERTAINTY ON WHETHER GALE FORCE WILL BE ABLE
TO BE REACHED GIVEN THE OFFSHORE WIND COMPONENT. HOWEVER...DID
UPGRADE AREAS FROM GARY EAST TO A GALE WARNING GIVEN THEIR BETTER
ONSHORE EXPOSURE. OTHERWISE...TEMPERATURES WILL FALL AS MUCH COLDER
AIR BUILDS IN WHICH WILL SET THE STAGE FOR FREEZING SPRAY. THE LOW
WILL BE SLOW TO DEPART TO THE EAST WHILE HIGH PRESSURE SPREADS INTO
THE NORTHERN PLAINS INTO TUESDAY NIGHT. THIS WILL KEEP WINDS STRONG
INTO TUESDAY EVENING BUT SPEEDS LOOK TO FALL JUST BELOW GALE FORCE
TUESDAY EVENING OR TUESDAY NIGHT...BUT SOME GALE FORCE GUSTS MAY
CONTINUE EVEN THROUGH WEDNESDAY. WILL KEEP 30 KT IN THE FORECAST FOR
THIS TIME FRAME FOR NOW THOUGH. THE PRESSURE GRADIENT WILL GRADUALLY
WEAKEN THROUGH THURSDAY AS THE LOW FILLS TO THE EAST AND THE HIGH
BROADENS TO THE WEST. NORTHEASTERLY LOW LEVEL FLOW LOOKS TO SET UP
NEXT WEEKEND WITH THE MAIN TRACK OF LOW PRESSURE SYSTEMS POSITIONED
SOUTH OF THE LAKE.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
ILZ022 UNTIL 11 AM MONDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002 UNTIL 11 AM MONDAY.
LM...GALE WARNING...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
GALE WATCH...LMZ740-LMZ741-LMZ742-LMZ743...10 PM MONDAY TO 9 PM
TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
538 AM CDT MON MAR 18 2013
.DISCUSSION...
529 AM CDT
A WINTER ADVISORY HAS BEEN ISSUED FOR A PORTION OF NORTHERN
ILLINOIS AND NORTHWEST INDIANA THROUGH 11 AM...WITH SLEET AND
FREEZING RAIN THE MAIN CONCERNS.
LATEST RADAR IMAGERY CONTINUES TO SHOW PRECIP SHIELD BLOSSOMING
EARLY THIS MORNING AS LARGE SCALE FORCING INCREASES ACROSS THE
AREA. THIS FORCING COINCIDING WITH A THERMAL PROFILE SUPPORTIVE OF
A WINTRY MIX...HAS RESULTED IN WIDESPREAD SLEET AND FREEZING RAIN
BEING REPORTED. AT THE OFFICE HERE IN ROMEOVILLE...MORE SLEET
ACCUMULATION HAS BEEN NOTICED OVER THE LAST HOUR. THIS SLEET
ACCUMULATION AS WELL AS THE FURTHER BLOSSOMING OF THE PRECIP
SHIELD IS WHAT HAS PROMPTED THE ADVISORY. ALTHOUGH ANY SNOW/SLEET
ACCUMULATION WILL REMAIN RATHER MINOR AROUND AN INCH...ITS ONCE
AGAIN THE SLEET ACCUMULATION COINCIDING WITH LIGHT FREEZING RAIN
WHICH IS THE MAIN CONCERN...CONCERNS OF SLIPPERY CONDITIONS FOR
THE MORNING COMMUTE. STILL EXPECT FURTHER SNOW ACCUMULATION LATER
THIS MORNING INTO THE AFTERNOON...BUT WITH SNOW THE LIKELY PRECIP
TYPE.
RODRIGUEZ
&&
.PREV DISCUSSION...
406 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH A
WINTRY MIX OF PRECIP ONGOING...AND THEN CONTINUING THROUGH THE
REMAINDER OF THE DAY WITH SNOW LIKELY ACROSS THE NORTHERN THIRD OF
THE CWA WHILE A RAIN/SNOW MIX FURTHER SOUTH TOWARDS THE I80
CORRIDOR...AND THEN ALL RAIN ACROSS THE SOUTHERN TIER OF COUNTIES.
LATEST RADAR IMAGERY IS DEPICTING AN AREA OF PRECIPITATION
SPREADING NORTH ACROSS PARTS OF NORTHEAST ILLINOIS AND NORTHWEST
INDIANA AS AN MID LEVEL WAVE TRACKS NORTHEAST ACROSS THE REGION.
LATEST REPORTS CONTINUE TO SUPPORT A WINTRY MIX THAT HAS BEEN
ANTICIPATED WITH SNOW OR SLEET FALLING ON THE NORTHERN FRINGE OF
THIS PRECIP SHIELD FROM STREATOR IN ILLINOIS EAST TO RENSSELAER IN
INDIANA...WHILE A RAIN SNOW MIX HAD BEEN REPORTED JUST SOUTH OF
THIS LINE. OVER THE NEXT COUPLE OF HOURS THIS TREND WILL LIKELY
CONTINUE AS THIS WINTRY MIX MOVES NORTH TOWARD THE CHICAGO METRO
AREA. ALTHOUGH WEAK...LATEST RAP ANALYSIS IS SHOWING SOME WAA
AIDING IN THIS DEVELOPMENT AND EXPECT THIS WEAK WAA TO FURTHER AID
THIS MORNING UNTIL MORE LARGE SCALE SUPPORT ARRIVES FROM THE WEST.
EXPECT SNOW OR SLEET WITH ONLY MINOR ACCUMULATIONS INITIALLY EARLY
THIS MORNING ALONG AND NORTH OF INTERSTATE 80...JUST SOUTH OF THE
INTERSTATE 80 CORRIDOR A RAIN SNOW MIX WILL BE LIKELY CONTINUE.
SURFACE TEMPS THIS MORNING HAVE BEEN SLOWLY FALLING WITH CURRENT
TEMPS AT OR JUST BELOW FREEZING ACROSS MUCH OF THE CWA. IN THOSE
AREAS WHERE LIGHT RAIN DOES OCCUR...THESE SURFACE TEMPERATURES
WILL SUPPORT THE POTENTIAL FOR BRIDGES AND ELEVATED ROADWAYS TO
ACCUMULATE A THIN LAYER OF ICING. ALTHOUGH THIS WINTRY MIX HAD
BEEN FALLING OVER THE LAST COUPLE OF HOURS...REPORTS HAD NOT
INDICATED ANY WIDESPREAD SLIPPERY CONDITIONS BUT WITH ROADS
REMAINING ONLY WET AT THAT TIME. WOULD SUSPECT THAT SLIPPERY
CONDITIONS ARE CURRENTLY DEVELOPING AND COULD POSSIBLY CONTINUE TO
DEVELOP OVER THE NEXT COUPLE OF HOURS. OF GREATEST CONCERN AT THIS
TIME FOR THESE SLIPPERY CONDITIONS WOULD BE THE I80 CORRIDOR WHERE
CURRENTLY THE STRONGEST RETURNS ON RADAR ARE LOCATED AS WELL AS
WITH SURFACE TEMPS JUST BELOW FREEZING. HAVE REISSUED AN SPS AT
THIS TIME FOR THOSE AREAS...WHILE NOT ISSUING ANY OTHER HEADLINES
AT THIS TIME. FORCING FOR THIS CURRENT PRECIP ACROSS THE CWA
SHOULD EXIT OVER THE NEXT COUPLE OF HOURS...WITH LATEST SHORT TERM
GUIDANCE SHOWING A DIMINISHING TREND WITHIN THE OVERALL EXTENT OF
THIS PRECIP. RESIDENCE TIME FOR ANY FURTHER LINGERING PRECIP IN
THESE AREAS SHOULD BE LIMITED THIS MORNING...AS THIS PRECIP AXIS
SLOWLY LIFTS NORTH. ALTHOUGH A DIMINISHING TREND HERE IN THE NEAR
TERM IS LIKELY...ONCE AGAIN STILL ANTICIPATE A NORTHWARD PUSH OF
THIS PRECIP.
LARGE SCALE FORCING FOR ASCENT WILL INCREASE THROUGH MID MORNING
AS THE CURRENT UPPER LEVEL TROUGH JUST TO THE WEST PUSHES EAST.
THIS IS ALREADY BEGINNING TO OCCUR OVER AREAS IN EASTERN IOWA
WHERE LIGHT RETURNS ARE BEGINNING TO SHOW UP ON RADAR. EXPECT
FURTHER DEVELOPMENT THROUGH MID TO LATE MORNING WITH A MIXED BAG
OF PRECIPITATION STILL LIKELY. ALTHOUGH...LATEST GUIDANCE IS
SHOWING THAT COLDER AIR WILL BE IN PLACE FURTHER SOUTH ACROSS THE
CWA THAN PREVIOUSLY ANTICIPATED WITH THE NUDGE OF WARMER AIR ALOFT
NOT AS PRONOUNCED FOR THIS MORNING OR MOST OF THE DAY...WITH
LATEST AMDAR SOUNDINGS SUPPORTED THESE THERMAL PROFILES. WITH THAT
IN MIND...HAVE SNOW OR SLEET POSSIBLE THROUGH MID MORNING FOR THE
NORTHERN HALF OF THE CWA ACROSS NORTH CENTRAL AND NORTHEAST
ILLINOIS WITH MORE LIQUID TYPE PRECIP EXPECTED FURTHER SOUTH.
SURFACE TEMPS WILL BE RISING THROUGH MID MORNING WITH ANY FURTHER
THREAT OF FREEZING RAIN IN THE CURRENT LOCATIONS BECOMING LESS
LIKELY. AS THIS UPPER LEVEL TROUGH SWINGS ACROSS THIS SNOW/SLEET
AND THEN SNOW THROUGH MID DAY AND EARLY AFTERNOON...DO THINK THERE
WILL BE SOME MINOR ACCUMULATIONS FOR AREAS ALONG AND NORTH OF THE
INTERSTATE 88 CORRIDOR INCLUDING THE WEST/NORTHWEST/NORTHERN
SUBURBS OF CHICAGO. ONE TO TWO INCHES WILL BE POSSIBLE NEAR THE
WISCONSIN BORDER WITH THREE INCHES AN OUTSIDE POSSIBILITY FOR
ISOLATED LOCATIONS...AND AROUND AN INCH FURTHER SOUTH. A TREND
TOWARDS MORE DRIZZLE WILL BE POSSIBLE BY MID AFTERNOON BUT AS THIS
OCCURS...MUCH COLDER AIR WILL BE SWEEPING THROUGH THE CWA. THIS
COULD HELP FOR FURTHER CRYSTALS TO DEVELOP AND HELP LIGHT SNOW TO
LINGER AROUND INTO THE AFTERNOON AND EARLY EVENING BUT WITH LITTLE
OR NO ADDITIONAL ACCUMULATION LIKELY. COLDER TEMPS STILL ON PAR
FOR THIS WEEK...STARTING OFF TONIGHT WITH LOW TO MID TEENS
POSSIBLE ACROSS MUCH OF THE CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* TIMING/TYPE OF PRECIPITATION THROUGH THE MORNING.
* MVFR/IFR CONDITIONS DEVELOPING THEN CONTINUING THROUGH THE
MORNING.
* GUSTY EAST WINDS NEAR 20 KT THROUGH AROUND
DAYBREAK...DIMINISHING AND BECOMING WEST-SOUTHWEST MIDDAY AND
INCREASING TO 20-30 KT BY THIS EVENING.
MDB
//DISCUSSION...UPDATED 09Z...
TRICKY PRECIP FORECAST CONTINUES THIS MORNING. BAND OF LIGHT
PRECIP CONTINUES TO MARCH NORTHWARD TOWARDS THE TERMINALS AND HAS
REACHED GYY AND WILL BE REACHING THE REMAINING TERMINALS IN THE
NEXT 1-2 HOURS. BASED ON SURFACE OBS SLEET SEEMS TO BE A DOMINANT
PRECIP TYPE BUT SUSPECT THAT SNOW IS MIXED IN AS WELL. HAVE SEEN
LITTLE IN THE WAY OF VSBY REDUCTION SUPPORTING THE LIGHT
INTENSITY. CIGS ARE ALSO LOWERING TO MVFR RATHER QUICKLY SO HAVE
ADJUSTED DOWNWARD CIG TREND TIMING SLIGHTLY. BASED ON LATEST TRENDS
AM EXPECTING THAT LIGHT PRECIP WILL CONTINUE ON AND OFF THROUGH
THE MORNING AS THERE HAS BEEN SOME REDEVELOPMENT ON THE SOUTHERN
PORTION OF THE APPROACHING BAND. AN EASTWARD MOVING BAND ACROSS
CENTRAL IOWA LOOKS TO ARRIVE LATE THIS MORNING AND MAY NOT EXIT
THE TERMINALS UNTIL EARLY AFTERNOON. WILL FURTHER EVALUATE BUT MAY
NEED TO INCLUDE STEADIER PRECIP UNTIL AROUND 20Z VS. THE CURRENT
-DZSN FROM 18-21. STILL APPEARS THAT MDW/GYY WILL HAVE THE BEST
CHANCE FOR SOME LIQUID PRECIP MIXED IN THROUGH THE MORNING AS NOSE
OF WARMER AIR PUSHES IN...WHERE ORD/DPA/RFD LOOK TO REMAIN MORE
SNOW/SLEET BUT IT MAY BE CLOSE AT ORD/DPA. WILL CONTINUE TO
MONITOR TRENDS AND ADJUST P-TYPE AS NEEDED.
MDB
FROM 06Z...
LOW PRESSURE OVER THE CENTRAL DAKOTAS WILL CONTINUE EASTWARD TO
LAKE SUPERIOR TODAY WHILE ANOTHER LOW NEAR THE MISSOURI BOOTHEEL
MOVES UP THE OHIO RIVER VALLEY. PRECIPITATION CONTINUES TO LIFT
NORTHWARD ACROSS CENTRAL ILLINOIS THOUGH THE BULK OF THIS IS
MOVING MORE TOWARDS THE NORTHEAST ACROSS CENTRAL INDIANA BUT
ADDITIONAL PRECIPITATION IS MOVING EASTWARD ACROSS CENTRAL IOWA.
PRECIPITATION WILL WORK INTO THE TERMINALS STARTING A FEW HOURS
FROM NOW. A MIX OF PRECIP TYPES IS EXPECTED AS WARMER AIR NOSES IN
ALOFT AND SURFACE TEMPS INITIALLY HOVER AROUND OR JUST BELOW
FREEZING BEFORE WARMING TOWARD MIDDAY. NORTHERN AREAS INCLUDING
ORD/RFD/DPA LOOK TO SEE PRIMARILY SNOW BUT SOME SLEET IS POSSIBLE
TOO AS WARM AIR APPROACHES ALOFT. SOUTHERN AREAS INCLUDING MDW/GYY
LOOK TO HAVE MORE OF A MIX OF RAIN AND SNOW WITH FREEZING RAIN
POSSIBLE THROUGH MID MORNING...AT LEAST AT TIMES...BEFORE SURFACE
TEMPS WARM ABOVE FREEZING. THE BULK OF THE PRECIPITATION IS
EXPECTED TO FALL PRIOR TO 18-20Z WHEN MID LEVEL MOISTURE AND
FORCING DIMINISHES...BUT SOME DRIZZLE MAY LINGER THROUGH EARLY
AFTERNOON. SOME SLUSHY ACCUMULATION IS POSSIBLE...ESPECIALLY
TOWARD RFD WHERE TEMPS WILL BE COLDEST OVERALL AND THIS WOULD
MAINLY ACCUMULATE DURING THE MORNING.
EAST-SOUTHEAST WINDS WILL CONTINUE WITH GUSTS TO AROUND 20 KT AT
TIMES THROUGH DAYBREAK BUT SPEEDS SHOULD EASE UP MID/LATE MORNING
BEFORE WINDS SHIFT TO THE SOUTHWEST THEN WEST THIS AFTERNOON. A
STRONG PUSH OF COLDER AIR WILL PUSH TEMPS BACK BELOW FREEZING LATE
IN THE DAY/THIS EVENING WITH STEEP LAPSE RATES SUPPORTING SOME
RENEWED SNOW FLURRY/SNOW SHOWER DEVELOPMENT BY EVENING WHICH MAY
CONTINUE OVERNIGHT AS WELL. WIND SPEEDS WILL ALSO PICK UP AS WINDS
SHIFT LATE IN THE DAY WITH GUSTS INCREASING TO AROUND 30 IF NOT 35
KTS FOR THE EVENING AND OVERNIGHT.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM CONFIDENCE IN TIMING/TRENDS AND TYPE OF PRECIP.
* MEDIUM CONFIDENCE IN PERIOD OF PREVAILING IFR CIG/VIS DURING
MORNING/MIDDAY.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY THROUGH SATURDAY...MAINLY VFR. GUSTY WEST WINDS TUE.
RATZER
&&
.MARINE...
323 AM CDT
LOW PRESSURE CONTINUES TO MOVE EAST ACROSS THE EASTERN DAKOTAS AND
WILL REACH EASTERN LAKE SUPERIOR TUESDAY MORNING. ANOTHER LOW IS
ALSO MOVING UP THE OHIO RIVER VALLEY AND WILL MERGE WITH THE MAIN
LOW TUESDAY. EAST TO SOUTHEAST WINDS CONTINUE ACROSS LAKE MICHIGAN
THIS MORNING WITH THE STRONGEST SPEEDS ACROSS THE CENTRAL SECTION OF
THE LAKE. THE PRESSURE GRADIENT WILL WEAKEN THROUGH THE MORNING
ALLOWING SPEEDS TO EASE UP WITH WINDS THEN SHIFTING TO THE WEST AND
SOUTHWEST THROUGH THE AFTERNOON. THE WEAKENING WINDS AND SHIFT IN
DIRECTION SHOULD HELP TO KNOCK WAVES DOWN SO WILL PLAN ON LETTING
THE SMALL CRAFT ADVISORY FOR THE ILLINOIS NEARSHORE WATERS EXPIRE AT
18Z. WEST WINDS WILL RAMP UP TO 35-40 KT GALES ACROSS THE SOUTHERN
TWO-THIRDS OF THE LAKE THIS EVENING WITH THE FAR NORTHERN SECTION
LIKELY BEING HELD TO AROUND 30 KT THANKS TO THE NEARBY PASSAGE OF
THE SURFACE LOW TONIGHT. HAVE UPGRADED THE GALE WATCH TO A GALE
WARNING FOR THE OPEN WATERS. ISSUED A GALE WATCH FOR THE ILLINOIS
NEARSHORE WATERS AS WELL AS THE INDIANA WATERS FROM CALUMET HARBOR
TO GARY...WITH SOME UNCERTAINTY ON WHETHER GALE FORCE WILL BE ABLE
TO BE REACHED GIVEN THE OFFSHORE WIND COMPONENT. HOWEVER...DID
UPGRADE AREAS FROM GARY EAST TO A GALE WARNING GIVEN THEIR BETTER
ONSHORE EXPOSURE. OTHERWISE...TEMPERATURES WILL FALL AS MUCH COLDER
AIR BUILDS IN WHICH WILL SET THE STAGE FOR FREEZING SPRAY. THE LOW
WILL BE SLOW TO DEPART TO THE EAST WHILE HIGH PRESSURE SPREADS INTO
THE NORTHERN PLAINS INTO TUESDAY NIGHT. THIS WILL KEEP WINDS STRONG
INTO TUESDAY EVENING BUT SPEEDS LOOK TO FALL JUST BELOW GALE FORCE
TUESDAY EVENING OR TUESDAY NIGHT...BUT SOME GALE FORCE GUSTS MAY
CONTINUE EVEN THROUGH WEDNESDAY. WILL KEEP 30 KT IN THE FORECAST FOR
THIS TIME FRAME FOR NOW THOUGH. THE PRESSURE GRADIENT WILL GRADUALLY
WEAKEN THROUGH THURSDAY AS THE LOW FILLS TO THE EAST AND THE HIGH
BROADENS TO THE WEST. NORTHEASTERLY LOW LEVEL FLOW LOOKS TO SET UP
NEXT WEEKEND WITH THE MAIN TRACK OF LOW PRESSURE SYSTEMS POSITIONED
SOUTH OF THE LAKE.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-
ILZ022 UNTIL 11 AM MONDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002 UNTIL 11 AM MONDAY.
LM...GALE WARNING...LMZ080-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ872-LMZ874-LMZ876-LMZ878...10 PM MONDAY TO 9 PM
TUESDAY.
GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
GALE WATCH...LMZ740-LMZ741-LMZ742-LMZ743...10 PM MONDAY TO 9 PM
TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
549 AM CDT MON MAR 18 2013
.DISCUSSION...
AS ALWAYS THERE IS ROOM FOR IMPROVEMENTS WHICH IS WHY WE DO LIKE
TO UPDATE THE FORECAST...BUT NOW THIS WHOLE WEEK IS A REAL HEAD
SCRATCHER INSIDE OF A MODEL RUN. EVEN THE DAY AHEAD IS GETTING OFF
TRACK WITH SOME OF THE AVAILABLE GUIDANCE. OBSERVATION IS ALWAYS A
GOOD STARTING PLACE WITH THE I-30 CORRIDOR RANGING IN THE 50S AND
MID TO UPPER 60S ELSEWHERE. THIS STATIONARY FRONT STRETCHES JUST
SOUTH OF I-30 IN NE TX AND THEN LIFTS NORTH OF I-30 AT TXK AND
THEN BACK TO THE SOUTH OF I-30 INTO LITTLE ROCK. WE ARE NOT GOING
TO SEE MUCH MOVEMENT HERE OVER THE NEXT FEW HOURS...BUT NAM
GUIDANCE PICKS UP SFC WINDS AS THE FRONT STARTS BACK TO THE SOUTH
OVER NE TX LATE THIS MORNING INTO THE EARLY AFTERNOON...GETTING
INTO SHV BY 21Z AND THE REMAINDER OF THE CWA NEARLY BY 00Z...MAYBE
A BIT FAST ON THAT LAST SEGMENT.
OTHERWISE...THE MID LEVEL CAP HAS BEEN TOO MUCH FOR ANYTHING OTHER
THAN A FEW SHALLOW LIGHT SHOWERS. THE WATER VAPOR SHOWS A SHORT
WAVE KNOCKING ON OUR DOOR OVER OK/N TX AND NNE SFC GUSTS ARE
SPREADING ACROSS THE RED RIVER THERE IN IT/S WAKE. THE SFC
GRADIENT IS WEAK...BUT THE SHORT WAVE IS GOING TO HELP THE SFC
BOUNDARY GET MOVING AS NAM GUIDANCE SUGGESTS. THE DISTURBANCE
SHOULD HELP TO WEAKEN THE CAP AND THE EXPECTATION IS FOR SCATTERED
DEVELOPMENT BOTH PRE AND POST FRONTAL...LATE THIS MORNING AND
DURING MUCH OF THE AFTERNOON. WE HAVE GONE FROM A SLIGHT RISK TO
GENERAL FOR THE DAY WITH THE MORNING TIME FRAME GENERALLY A TOUGH
TIME TO GET ANYTHING GOING ANYWAY. OUR RADAR HAS BEEN MOSTLY QUIET
AS THE LOW LEVEL JET HAS JUST BEEN STRONGER RIGHT BENEATH THE CAP
AND NOT STRONG ENOUGH IN THE LOWEST LEVELS. OVERNIGHT...WE HAVE NOT
SEEN ENOUGH ENERGY RIDING OVER THE STATIONARY FRONT AND WE APPEAR
TO NEED DAYTIME HEATING TO MAKE A LAST DITCH EFFORT AT DEVELOPMENT
OVER THE CWA LATER THIS MORNING. TIMING IS EVERYTHING IN THIS
BUSINESS AND HURRY UP AND WAIT IS ALL TOO OFTEN THE REALITY. AT
ANY RATE...THE SFC HIGH PRESSURE GRADIENT IS NOT VERY STRONG EVEN
WELL BEHIND THE FRONT WITH THE GFS AT 12Z LOOKING AT 1015 MB OVER
SW KN WITH OBS SHOWING 1012 STILL IN NW KN. THE NAM IS EVEN
STRONGER WITH 1017MB AT 12Z. THE RAP INITIALIZES BEST RIGHT NOW
AND DOES END UP LOOKING MUCH THE NAM AND GFS BY LATER THIS
AFTERNOON AS FAR AS SFC PRESSURES INCREASING IN OUR CWA.
THE MID WEEK PERIOD IS COMPARABLE TO WHAT WE HAVE HAD OUT...BUT
HAS TRENDED DRIER LONGER THROUGH MIDWEEK WITH THE NEXT EVENT
LIKELY TO BE OVERRUNNING AND A MUCH BETTER RAIN MAKER FOR THE AREA
AS A WHOLE LATE IN THE WORK WEEK. THE ECMWF IS PREFERED AND TAKES
OVER WHERE GFS LEAVES OFF DURING MID WEEK. THE MEX GUIDANCE HAD
60S...BUT HAS GONE 180 OUT AND IS NOW LOOKING AT 80S FOR TEMPS
INTO SATURDAY WITH EURO MORE OF A STATUS QUO APPROACH AND WHILE
THERE MAY BE SOME CHANGES TO THE LONGER TERM AS WELL...WE WILL
HOLD OFF ANOTHER MODEL RUN OR TWO TO SEE IF WE CAN GET SOME KIND
OF AGREEMENT. /24/
&&
.AVIATION...
EXPECT MVFR TO OCCASIONAL IFR CEILINGS/VISIBILITIES FOR A START TO
THE TERMINALS FOR THE 18/12 UTC ISSUANCE. COMPLEX WEATHER PATTERN
OVER THE FOUR STATE REGION THIS MORNING. A SURFACE LOW TO THE WEST
WITH A NEARLY STATIONARY BOUNDARY REACHING EAST INTO SOUTHWEST
ARKANSAS. SOUTHERLY WINDS AFFECTING THE TERMINAL SITES THIS
MORNING...BUT WITH THE PASSAGE OF AN UPPER DISTURBANCE LATER DURING
THE DAY...EXPECTING THE SURFACE LOW TO SINK SOUTHEAST WITH A COLD
FRONT SPREADING INTO THE AREA...PROVIDING A SMALL CHANCE OF
SHOWERS...WITH MORE ISOLATED THUNDERSTORMS. IN WAKE OF THE FRONTAL
PASSAGE THE WINDS WILL BECOME WEST AND THEN NORTHWEST FROM NORTHWEST
TO SOUTHEAST OVER THE FOUR STATE REGION DURING THE DAY. THE COLD
FRONT SHOULD APPROACH A KELD TO KSHV AND KLFK LINE NEAR 18/19 UTC
AND THEN OUT OF THE AREA BY 19/00 UTC TUESDAY. DRY AIR WILL SPREAD
SOUTHWARD...WITH CEILINGS DISSIPATING. SURFACE WIND SOUTH TO
SOUTHWEST 6 TO 12 KNOTS PRIOR TO FRONTAL PASSAGE...THEN GRADUALLY
BECOMING WEST AND NORTHWEST 8 TO 14 KNOTS. AFTER 19/00 UTC THE WINDS
WILL BE MORE NORTHERLY AROUND 4 TO 8 KNOTS. /06/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 76 47 70 48 71 / 20 10 10 30 20
MLU 77 47 68 45 69 / 30 10 10 20 20
DEQ 64 36 67 38 68 / 30 10 10 20 10
TXK 69 43 67 43 68 / 20 10 10 20 10
ELD 74 41 67 41 69 / 30 10 10 20 10
TYR 73 45 69 50 70 / 20 10 10 30 10
GGG 75 46 68 47 71 / 20 10 10 30 10
LFK 80 49 74 51 74 / 20 10 10 30 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
24/06
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
733 AM EDT MON MAR 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 551 AM EDT MON MAR 18 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A VIGOROUS LOOKING
SHORTWAVE TROF MOVING ACROSS THE NRN PLAINS TOWARD THE UPPER
MISSISSIPPI VALLEY. BAND OF SNOW HAS BEEN SLOWLY ORGANIZING DURING
THE NIGHT ACROSS MN AHEAD OF FEATURE. FRONTAL BOUNDARY DRAPPED
ACROSS THE OHIO/TENNESSEE VALLEYS IS EFFECTIVELY PREVENTING A GOOD
SURGE OF MOISTURE N TO THE UPPER LAKES AHEAD OF WAVE. PER 00Z
RAOBS...PRECIPITABLE WATER VALUES UPWARDS OF 1 INCH ARE SOUTH OF
THE BOUNDARY WHILE VALUES ARE ONE-QUARTER TO ONE-HALF INCH OVER THE
NRN PLAINS...JUST A LITTLE ABOVE NORMAL FOR THIS TIME OF YEAR. THIS
WILL WORK TO KEEP SNOW ACCUMULATIONS IN CHECK DESPITE VIGOROUS
DYNAMICS ASSOCIATED WITH SHORTWAVE BECOMING INCREASINGLY NEGATIVELY
TILTED AS IT MOVES ACROSS THE WRN GREAT LAKES LATE THIS
AFTN/TONIGHT.
OVERALL...FCST FOR TODAY/TONIGHT WAS IN GOOD SHAPE...SO NO MAJOR
ADJUSTMENTS WERE MADE. SLOWED TIMING OF SNOW JUST A BIT BASED ON
OVERNIGHT RADAR TRENDS AND MODEL TRENDS. MODEL CONSENSUS PCPN
AMOUNTS ARE ROUGHLY 0.2 TO 0.4 INCHES. WITH SNOW RATIOS LIKELY
AROUND 15 TO 1...ADVY FOR GENERAL SNOWFALL OF 3 TO 6 INCHES LOOKS ON
TRACK. MOST LOCATIONS WILL PROBABLY BE IN THE 3-4 INCH RANGE...AND
THE SNOW MAY FALL AT DECENT RATE FOR A WHILE.
SNOW WILL DIMINISH TO PATCHY -SN W TO E TONIGHT AS BAND OF SNOW TIED
TO STRONG FORCING AHEAD OF SHORTWAVE DEPARTS. ATTENTION OVERNIGHT
THEN TURNS TO THE W WHERE STRONG NW WINDS WILL DEVELOP IN THE WAKE
OF SFC LOW MOVING ACROSS LAKE SUPERIOR. WHILE THERE IS SOME
UNCERTAINTY IN TIMING THE ARRIVAL OF THE STRONG NW WINDS...WHICH
WILL ARRIVE OVER GOGEBIC/ONTONAGON COUNTIES BEFORE THE
KEWEENAW...DEEP MOISTURE/CONVERGENT CYCLONIC FLOW AND A DEEP DGZ
SUGGEST VERY HVY LAKE ENHANCED SNOW WILL LIKELY DEVELOP FROM KIWD N
THRU THE KEWEENAW BY DAYBREAK. COULD EASILY SEE SNOWFALL RATES OF
1-3IN/HR INTO TUE MORNING ACROSS THE HIGHER TERRAIN OF THE W. BLSN
WILL ALSO BECOME AN INCREASING HAZARD AS NW WINDS WILL GUST OVER
30MPH TO AS HIGH AS 40MPH...ESPECIALLY IN OPEN AREAS NEAR LAKE
SUPERIOR. WHITE-OUTS WILL BE A GOOD POSSIBILITY DUE TO COMBINATION
OF HVY SNOW/BLSN.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 551 AM EDT MON MAR 18 2013
MODELS AGREE THAT STRONG SHORTWAVE MOVING THROUGH THE REGION TODAY
HELPS TO ESTABLISH LOW-MID LEVEL TROUGHING THROUGH THE WEEK. ONCE
SFC-H85 LOWS PUSH EAST OF LK SUPERIOR...EXPECT COLD AIR TO POUR
ACROSS THE ENTIRE GREAT LAKES REGION. SINCE THE TROUGH IS NEARLY
STATIONARY A LOT OF MOISTURE THROUGH H7 PERSISTS ACROSS THE REGION
THROUGH AT LEAST WEDNESDAY. ENOUGH COLD AIR IN BLYR TO SUPPORT AT
LEAST MODERATE LK EFFECT SNOWS THROUGH MIDWEEK BEFORE CONDITIONS
BECOME MORE MARGINAL BY LATE WEEK AS MOISTURE ABOVE H9 DIMINISHES
AND LOW-LEVEL FLOW BECOMES NOT AS CYCLONIC. PROLONGED PERIOD OF
MODERATE LK EFFECT SNOWS EXPECTED WITH POTENTIAL HEAVY LK EFFECT AT
TIMES THROUGH WEDNESDAY GIVEN DEEP MOISTURE IN PLACE...STRONGEST
LOW-LEVEL CONVERGENCE AND GREATEST INSTABILITY WITH DELTA T/S OVER
15C AND LAKE EQL TOWARD 10KFT. SOUNDINGS ALSO SHOW MAJORITY OF LAKE
CONVECTIVE LAYER WITHIN THE DGZ WHICH HELPS BOOST SLR/S OVER 20:1.
OTHER FACTOR TUESDAY/TUESDAY NIGHT AND INTO WEDNESDAY MORNING WILL
BE STRONG WINDS WITH OVER 30 KTS LOCATED WITHIN THE BLYR. GUSTS OVER
35KT/40 MPH SEEM POSSIBLE IN THE MOST VIGOROUS LK EFFECT CONVECTION.
BLOWING SNOW WILL INCREASE BY LATER TUESDAY AFTN IN AREAS FAVORED BY
NW WINDS AND THIS HAZARD WILL CONTINUE THROUGH MUCH OF WEDNESDAY.
A COUPLE MAIN ISSUES TO SORT OUT AND THESE ARE NOT TRIVIAL AS THEY
IMPACTED HEADLINE DECISIONS THIS MORNING. MAIN ISSUE THROUGH TUESDAY
IS THERE APPEARS TO BE A BREAK BTWN THE SYNOPTIC SNOW THAT MOVES
THROUGH THIS AFTN/TONIGHT AND INCREASING LK ENHANCED SNOW OVER EAST
ON TUESDAY AFTN. LOCAL WRF AND REGIONAL GEM AGRESSIVE IN DEVELOPING
SFC TROUGH OVER EASTERN CWA ON TUESDAY MORNING TO THE SOUTH OF
PRIMARY SFC LOW OVER EASTERN LK SUPERIOR. COARSER GFS HINTS AT THIS
IDEA AS WELL. WINDS AHEAD OF TROUGH BACK SW SO THAT LK EFFECT ISSUES
PROBABLY WILL NOT DEVELOP OVER THE FAR EAST UNTIL AFTER 18Z ON
TUESDAY. ONCE TROUGH SHIFTS THROUGH...LK EFFECT COULD BECOME QUITE
INTENSE JUST IN WAKE OF TROUGH AS CONVERGENCE RAMPS UP AND COLD AIR
ARRIVES LEADING TO QUICKLY INCREASING OVER-WATER INSTABILITY. GIVEN
CERTAIN BLSN HAZARD ALONG WITH HEAVIER LK ENHANCED SNOWFALL...A
WARNING MAY EVENTUALLY BE NEEDED. SINCE THERE WILL BE ENOUGH OF A
GAP BTWN THE SYNOPTIC SNOW AND HEAVIER LK ENHANCED SNOW LATER
TUESDAY DECIDED IN FAVOR OF WINTER STORM WATCH FOR EASTERN CWA NEAR
LK SUPERIOR 12Z TUESDAY THROUGH 12Z THURSDAY. DID NOT GET TOO
SPECIFIC WITH TIMING SINCE SOME MODELS DO SHOW QUICKER ONSET OF LK
ENHANCED SNOW THAN GEM-REGIONAL AND LOCAL-WRF...ESPECIALLY IN THE
MUNISING AND GRAND MARAIS AREAS. WESTERN TIER OF CWA IS MORE CLEAR
CUT. MAIN ISSUE OVER THE WEST IS HOW LONG TO RUN THE WARNING. KEPT
IT PRETTY SIMPLE AT THIS POINT AND KEPT WARNING IN PLACE UNTIL WINDS
IN BLYR BEGIN TO DECREASE BLO 25 KTS AND WHEN DEEPER MOISTURE STARTS
TO CUT OUT. ON BOTH ACCOUNTS IT APPEARS SUITABLE CUTOFF WAS DAYBREAK
ON THURSDAY MORNING. MORE LK EFFECT CONTINUES ON THURSDAY...BUT
SHOULD BE BEGINNING TO SHOW DIMINISHING TREND COMPARED TO MORE
FAVORABLE SETUP IN PLACE TUESDAY AND WEDNESDAY.
LK EFFECT DIMINISHES FURTHER INTO FRIDAY BUT PROBABLY WILL NOT GO
AWAY COMPLETELY AS LIGHT WIND PERSISTS OFF LK SUPERIOR. THOUGH H85
TEMPS ARE WARMING...COOL ENOUGH BENEATH LOWERING INVERSION TO HAVE
SOME LGT SNOW SHOWERS/FLURRIES. NO SIGNIFICANT WX INTO THE WEEKEND
BUT NOT ALL THAT WARM EITHER AS GENERAL TROUGHING CONTINUES. SINCE
MOST OF FOCUS WAS ON SNOW/BLSN AND HEADLINES...USED MODEL CONSENSUS
FOR THE FORECAST BEYOND THURSDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 732 AM EDT MON MAR 18 2013
LOW PRES APPROACHING FROM THE W WILL PUSH A BAND OF SNOW ACROSS
UPPER MI TODAY. WITHIN AN HR OR TWO OF THE ONSET OF SNOW...EXPECT
CONDITIONS TO FALL TO IFR. SNOW SHOULD BEGIN AT KIWD MID TO LATE
MORNING...AT KCMX EARLY THIS AFTN AND AT KSAW MID TO LATE AFTN.
PRIOR TO THE ARRIVAL OF THE SNOW...UPSLOPE SSE WINDS OFF LAKE
MICHIGAN WILL LIKELY RESULT IN LOW MVFR CIGS DEVELOPING AT KSAW
AROUND MID MORNING. SNOW SHOULD DIMINISH FOR A WHILE TONIGHT AND MAY
ALLOW CONDITIONS TO IMPROVE TO MVFR. THAT`S MOST LIKELY TO HAPPEN AT
KSAW. LATE TONIGHT...STRONG NW WINDS BEHIND THE LOW WILL BRING
MDT/HVY LAKE ENHANCED SNOW TO KIWD/KCMX WITH CONDITIONS LIKELY
FALLING TO LIFR.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 551 AM EDT MON MAR 18 2013
AS LOW PRES OVER THE EASTERN DAKOTAS MOVES E...TIGHT PRES GRADIENT
AHEAD OF THE LOW WILL BRING SE WINDS UP TO 30KT TODAY. GALES WILL
LIKELY OCCUR TOWARD MID LAKE PORTIONS OF NCNTRL AND ERN LAKE
SUPERIOR...IN PARTICULAR FROM AROUND WHITEFISH PT NW TOWARD PASSAGE
ISLAND. AFTER THE LOW EXITS TO THE E...NORTHWEST GALES WILL DEVELOP
FROM W TO E LATE TONIGHT/TUE. THE GALES WILL THEN CONTINUE INTO WED
OVER THE E HALF OF THE LAKE. WINDS WILL SLOWLY DIMINISH TO UNDER 25KT
FROM W TO E WED NIGHT/THU. THE COMBINATION OF COLD AIR/STRONG
WINDS/HIGH WAVES WILL LEAD TO PERIODS OF HVY FREEZING SPRAY TUE THRU
WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING FROM 2 PM THIS AFTERNOON TO 8 PM EDT
WEDNESDAY FOR MIZ001-003-004-084.
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 5 AM EDT
TUESDAY FOR MIZ006-007-014-085.
WINTER STORM WATCH FROM TUESDAY MORNING THROUGH THURSDAY MORNING
FOR MIZ006-007-085.
WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY FOR
MIZ002-009.
WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 2 AM EDT
TUESDAY FOR MIZ005-013.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 1 AM CDT TUESDAY FOR
MIZ010>012.
LAKE SUPERIOR...
GALE WARNING UNTIL 2 PM EDT WEDNESDAY FOR LSZ264-266-267.
GALE WARNING FROM 2 PM TUESDAY TO 2 PM EDT WEDNESDAY FOR
LSZ243>251-265.
GALE WARNING FROM 8 AM EDT /7 AM CDT/ TUESDAY TO 2 PM EDT /1 PM
CDT/ WEDNESDAY FOR LSZ162-240>242-263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
709 AM CDT MON MAR 18 2013
.UPDATE...
12Z AVIATION DISCUSSION ADDED BELOW.
&&
.DISCUSSION...
.PREV DISCUSSION...
/ISSUED 351 AM CDT MON MAR 18 2013/
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT.
AT 3 AM...THE INITIAL NARROW BAND OF MDT-HVY SNOW WAS ALIGNED FROM
ABOUT ST CLOUD TO FAIRMONT. VISIBILITIES HAVE FALLEN TO 1/4 MILE
IN SPOTS WITH RAPID ACCUMULATIONS OF SNOW. ACROSS WRN MN...FREEZING
DRIZZLE AND EVEN RAIN HAS BEEN REPORTED AS THE MID LEVEL DRY SLOT
CUTS OFF MOISTURE IN THE DGZ. COLD FRONT WAS LOCATED ESSENTIALLY AT
THE MN/SD BORDER WITH VERY STRONG WINDS BEING REPORTED ACROSS THE
DAKOTAS. ABERDEEN REPORTED A WIND GUST OF 58 MPH OVERNIGHT. DESPITE
THE TROUBLING TREND OF LIQUID PRECIPITATION FALLING ON THE SNOW
WHICH WAS NECESSARY FOR THE BLIZZARD TODAY...THE RAIN HAS BEEN QUITE
LIGHT. AS WINDS BEGIN TO GUST AROUND 50 MPH LATER THIS MORNING...THE
TOP CRUST OF SNOW WILL BE PENETRATED EASILY. FURTHERMORE...ADDITIONAL
SNOW SHOWERS THIS AFTERNOON WILL BRING INSURANCE FOR THE BLIZZARD
AS HIGH MOISTURE CONTENT IN THE DGZ EXTENDS FROM THE SFC TO TO
7KFT.
IN THE NEXT FEW HOURS...THE COLD FRONT WILL BEGIN TO CATCH UP TO
THE INITIAL SNOW BAND AND HELP IT EXPAND/INTENSIFY OVER ERN MN
AND WRN WI BY MID MORNING. HOPWRF AMONG OTHER HI-RES MODELS THAT
ARE NAILING THE CURRENT PLACEMENT OF THIS BAND INDICATE THIS
SCENARIO QUITE WELL WITH 1/4-1/3 INCH QPF...HEAVIEST OVER WI.
USING ABOUT A 13:1 RATIO WILL YIELD 3 TO 5 INCHES OF SNOW. AS THE
FRONT CLEARS...THE HEAVY SNOW WILL END BUT WINDS WILL CRANK UP AS
STRONG CAA STEEPENS LOW LEVEL LAPSE RATES. FORECAST SOUNDINGS
STILL SHOW 40+ KTS AT THE TOP OF THE BOUNDARY LAYER THIS AFTERNOON
OVER ERN/CNTRL MN AND 35 KTS OVER WRN WI. ALTHOUGH SUCH GUSTS MAY
OCCUR SPORADICALLY...MORE FREQUENT GUSTS OF ABOUT 5 KTS LESS ARE
EXPECTED. UPGRADED THE WINTER WEATHER ADVY OVER ERN MN TO A WINTER
STORM WARNING /EXCEPT FOR CHISAGO CO/. THIS IS WHERE 3 OR 4 INCHES
WILL COINCIDE WITH 40 MPH WIND GUSTS. LIGHTER GUSTS AND TOPOGRAPHY
ACROSS WRN WI WILL CUT DOWN ON SOME OF THE BLOWING POTENTIAL.
THUS...KEPT THE ADVISORY IN PLACE FOR THOSE LOCATIONS.
KEPT LIKELY POPS INTO THE EARLY EVENING OVER CNTRL/ERN MN AND WRN
WI FOR SNOW SHOWERS...BUT NOT ANTICIPATING MORE THAN AN INCH
FOLLOWING THE FRONT. SOME CLEARING EXPECTED LATER TONIGHT...BUT
WINDS WILL REMAIN GUSTY AND TEMPERATURES WILL PLUMMET INTO THE
SINGLE DIGITS BELOW ACROSS WRN MN AND SINGLE DIGITS ABOVE EAST.
WIND CHILLS WILL APPROACH ADVISORY CRITERIA OVERNIGHT...REACHING
AS LOW AS 25 BELOW OVER PARTS OF THE AREA.
A WEAK DISTURBANCE WILL ROTATE AROUND THE CYCLONIC FLOW AND INTO
THE UPPER MIDWEST TUESDAY. IT MAY SPARK OFF ANOTHER FEW SNOW
SHOWERS WITH STEEP LAPSE RATES EXTENDING INTO THE DGZ. A SECOND
DISTURBANCE WILL ROTATE AROUND WEDNESDAY. MORE SNOW SHOWERS COULD
OCCUR OVER ERN MN/WRN WI. FELT IT WAS PRUDENT TO ADD SCHC POP TO
ACCOUNT FOR THE POSSIBILITY FOR THESE PERIODS. HIGHS TUESDAY AND
WEDNESDAY WILL REMAIN IN THE TEENS TO LOW 20S...OR 20 TO 30
DEGREES BELOW AVERAGE.
WEDNESDAY NIGHT WILL BE COLD...THE QUESTION IS HOW COLD. RIDGE
AXIS WILL SLIDE INTO WRN MN OVERNIGHT WITH LIGHT WINDS EXPECTED.
AFTER SEEING WHAT HAPPENED SUNDAY MORNING WITH TEENS AND 20S BELOW
ACROSS NRN MN...THIS ATMOSPHERE SHARES VERY FEW CHARACTERISTICS OF
A TYPICAL MID/LATE MARCH COLD SPELL. CERTAINLY COULD SEE TEENS
BELOW ZERO IN AREAS WITH LIGHT/VARIABLE WINDS.
LONG TERM...THURSDAY THROUGH SUNDAY.
THE LONG TERM LOOKS COLD. LARGE HIGH PRESSURE WILL SPRAWL OVER
VIRTUALLY ALL OF CANADA WITH LIGHT E/NE FLOW PERSISTING THROUGH
THE WEEKEND FOR THE REGION. THE STORM TRACK WILL SLIDE WELL TO
THE SOUTH AND A PROLONGED PERIOD OF BENIGN WX IS EXPECTED.
TEMPERATURES ARE ALMOST CERTAINLY TOO WARM HEADING INTO THE
WEEKEND...AND FUTURE SHIFTS WILL LIKELY ADJUST TEMPS DOWNWARD WITH
TIME. MOS ARE FAVORING TOO MUCH OF CLIMATOLOGY BEYOND DAY 4.
BORGHOFF
&&
.AVIATION.../12Z TAF ISSUANCE/
SNOW OVER THE TWIN CITIES NOW AND WILL MOVE INTO THE EAU AREA
AROUND 13Z. COLD FRONT NEAR A STC TO ULM LINE AND WILL CLEAR OUT
BAND OF SNOW AS IT MOVES EAST. WHAT IS WORRISOME THOUGH IS THE
FACT THAT BETWEEN THE SNOW AND COLD FRONT DZ/FZDZ HAS BEEN
PREVALENT OVERNIGHT...SO ADDED A COUPLE HOUR TEMPO GROUP TO MSP TO
ACCOUNT FOR THAT. NOT EXPECTING FZDZ OVER WI AS COLD FRONT SHOULD
CATCH UP TO THE SNOW BAND BY THE TIME IT GETS OVER THERE...KEEPING
EVERYTHING ALL SNOW. HRRR HAS HAD A GOOD HANDEL ON SNOW ALL
NIGHT...SO USED IT TO TIME SNOW AND WIND SHIFT ACROSS THE AREA. AS
FOR THOSE WINDS...ALREADY GUSTING TO OVER 30 KTS IN WRN MN...WITH
EVEN A COUPLE OF 40+ KTS SEEN. THESE WINDS WILL WORK EAST ACROSS
THE AREA WITH THE FRONT. BASED ON RAP/NAM BUFKIT SOUNDINGS...
GUSTS TO OR ABOVE 30 KTS SHOULD END BY 3Z AT AXN...BUT CONTINUE TO
AROUND 6Z ACROSS WI. IN ADDITION...EXPECT CONVECTIVE SNOW SHOWERS
TO DEVELOP BY THE AFTERNOON...ESPECIALLY ACROSS CENTRAL MN...WHICH
SHOULD HELP FURTHER REDUCE ANY VSBYS ALREADY BEING REDUCED BY
BLSN. MAY SEE SOME VFR CIGS SNEAK INTO WRN MN THIS MORNING...BUT
DEEP MIXING WILL QUICKLY FILL IN THE CLOUDS...WITH IFR/MVFR CIGS
EXPECTED TO DOMINATE INTO THE EVENING...WITH IMPROVEMENTS TO VFR
WORKING FROM WEST TO EAST AFTER SUNSET.
KMSP...BACK EDGE OF SNOW ALREADY WORKING INTO THE WESTERN
METRO...WITH COLD FRONT ANOTHER 30 MILES OR SO BEHIND THAT. IN
BETWEEN...FZDZ REPORTS HAVE BECOME COMMON...SO WILL HAVE TO WATCH
FOR THAT FOR A COUPLE OF HOURS THIS MORNING BEFORE COLD FRONT
COMES THROUGH AT ABOUT 17Z. WITH THE WIND SHIFT TO BETWEEN 260 AND
290 BEHIND THE FRONT...WILL HAVE TO SWAP RUNWAY OPERATIONS DURING
THE LATE MORNING. CONFIDENCE IN VIS FORECAST LOW FOR THE
AFTERNOON. DO THINK BLOWING/DRIFTING SNOW WILL BE AN ISSUE...JUST
DO NOT KNOW IF IT WILL LEAD TO THE PROLONGED IFR VSBYS CURRENTLY
INDICATED IN TAF. NAM/RAP SOUNDINGS WOULD SAY STRONGEST WINDS WILL
BE SEEN BETWEEN 00Z AND 04Z TONIGHT...WITH GUSTS FINALLY BACKING
OFF AFTER 6Z...THOUGH WINDS SHOULD HAVE NO PROBLEM GUSTING TO
BETWEEN 20 AND 30 KTS AGAIN ON TUESDAY.
/OUTLOOK FOR KMSP/
TUE...VFR WITH MVFR CIGS POSSIBLE LATE. WINDS WNW AT 20G30KTS.
WED...VFR WITH MVFR CIGS POSSIBLE AFTERNOON. WINDS NW AT 15G25KTS.
THU...VFR. WINDS NE AT 5 TO 10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...BLIZZARD WARNING UNTIL 1 AM CDT TUESDAY FOR BLUE EARTH-BROWN-
CARVER-CHIPPEWA-DOUGLAS-FARIBAULT-FREEBORN-KANDIYOHI-LAC
QUI PARLE-LE SUEUR-MARTIN-MCLEOD-MEEKER-NICOLLET-POPE-
REDWOOD-RENVILLE-RICE-SCOTT-SIBLEY-STEARNS-STEELE-STEVENS-
SWIFT-TODD-WASECA-WATONWAN-WRIGHT-YELLOW MEDICINE.
WINTER STORM WARNING UNTIL 1 AM CDT TUESDAY FOR ANOKA-BENTON-
DAKOTA-GOODHUE-HENNEPIN-ISANTI-KANABEC-MILLE LACS-MORRISON-
RAMSEY-SHERBURNE-WASHINGTON.
WINTER WEATHER ADVISORY UNTIL 1 AM CDT TUESDAY FOR CHISAGO.
WI...WINTER WEATHER ADVISORY UNTIL 1 AM CDT TUESDAY FOR BARRON-
CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX.
&&
$$
BORGHOFF/MPG
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1055 AM EDT MON MAR 18 2013
.SYNOPSIS...
A COLD FRONT STALLED JUST SOUTH OF THE AREA WILL LIFT NORTH OF THE
AREA LATE TODAY...AS LOW PRESSURE MOVES THROUGH THE GREAT LAKES. THE
LOW WILL PUSH A COLD FRONT THROUGH THE REGION TUESDAY. HIGH PRESSURE
WILL BUILD OVER THE REGION ON WEDNESDAY AND THURSDAY. A SERIES OF
LOW PRESSURE AREAS ARE FORECAST TO MOVE OFF OF THE SOUTHEAST FRIDAY
INTO THE WEEKEND.
&&
.NEAR TERM /TODAY/...
AS OF 1000 AM MONDAY...UPDATED FOR WEDGE CONDITIONS LINGERING LONGER
INTO THIS AFTN. WEAK WAVE OF LOW PRES OFFSHORE OF HAT IS REINFORCING
WEDGE OVER AREA WITH WIDESPREAD LOW CLOUDS AND THREAT OF PATCHY
-RA/-DZ LINGERING INTO AFTN. LATEST NAM12 AND HRRR SOME BREAKS OVER
SRN SECTIONS LATE AFTN INTO EVENING WITH FRONT FINALLY LIFTING INTO
AREA. LOWERED MAX TEMPS AROUND 5 DEGS...MID 50S N TO AROUND 60 S.
/PREVIOUS DISCUSSION/
AS OF 715 AM MON...LATEST SFC ANALYSIS SHOWS COLD FRONT STALLED
JUST SOUTH OF THE NC/SC BORDER WITH SFC HIGH PRESSURE TO THE NORTH
EXTENDING OVER THE AREA. THIS SETUP IS RESULTING IN A WEDGE TYPE
CONDITIONS OVER EASTERN NC WITH MOIST E/NE FLOW...PATCHY LIGHT
RAIN/DRIZZLE AND WIDESPREAD STRATUS. NO SIG CHANGES NEEDED OTHER
THAN TO TWEAK GRIDS BASED ON LATEST TRENDS. STALLED FRONT WILL
LIFT NORTHWARD TODAY AS A WARM FRONT....AS SFC LOW PRESSURE MOVES
INTO THE GREAT LAKES. HIGH TEMPS WILL BE TRICKY AGAIN TODAY...AND
WILL DEPEND ON HOW QUICKLY THE WARM FRONT LIFTS THROUGH THE CWA.
WENT COOLER THAN GUIDANCE WITH HIGHS IN THE MID TO UPPER 50S IN
THE NORTHERN AREAS...AND LOW TO MID 60S SOUTH WHERE EXPECT MORE
SUNSHINE AND SLY FLOW. WEDGE COULD HOLD IN THE NW CWA WHICH WOULD
KEEP TEMPS SEVERAL DEGREES COOLER. CONTINUED 20-40 POPS THIS
MORNING INTO EARLY AFTERNOON WITH -RA/DZ...BEST CHANCES IN THE
NORTHERN CWA WITH BEST LIFT/MOISTURE...MAINLY ALONG AND N OF HWY
264. ISOLATED TO WIDELY SCT CHANCE OF SHOWERS THIS AFTERNOON AS
FRONT LIFTS NORTHWARD.
&&
.SHORT TERM /TONIGHT/...
AS OF 310 AM MON...BETTER CHANCE OF SHOWERS EXPECTED TONIGHT AHEAD
OF APPROACHING COLD FRONT. FORECAST SOUNDINGS CONTINUE TO SHOW
DECENT INSTABILITY AND SHEAR...SO WILL CONTINUE TO MENTION
ISOLATED TSTMS. AN ISOLATED STRONG STORM WILL BE POSSIBLE...MAINLY
BTWN 03-09Z. INCREASED POPS TO LIKELY OVERNIGHT BASED ON LATEST
GUIDANCE AND NSSL WRF. MILD OVERNIGHT LOWS IN THE 50S WITH CLOUDY
SKIES.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
AS OF 3 AM MONDAY...WITH FRONTAL BOUNDARY WORKING ITS WAY THROUGH
THE REGION DURING TUESDAY MORNING...WILL HANG ON TO HIGH CHANCE
POPS UNTIL AROUND MIDDAY TUESDAY BEFORE FRONT MOVES OFFSHORE IN
THE 15Z-18Z TIME FRAME. WEAK HIGH PRESSURE WILL THEN BUILD ACROSS
THE REGION TUESDAY NIGHT INTO WEDNESDAY. ANOTHER REINFORCING
CANADIAN COLD FRONT WILL DROP QUICKLY THROUGH THE AREA WEDNESDAY
NIGHT. GFS/ECMWF SHOW SOME LIGHT QPF WITH THIS FRONT AND WILL
CARRY A SLIGHT CHC OF LIGHT RAIN AS BOUNDARY LAYER TEMPS WILL BE
TOO WARM FOR ANY WINTRY PRECIPITATION. THE CANADIAN HIGH WILL
BUILD SOUTH BEHIND THE FRONT THURSDAY. DIFFERENCES CONTINUE IN THE
HANDLING OF THE UPPER-LEVEL ENERGY FROM THE GFS AND ECMWF FOR
THURSDAY NIGHT INTO THE WEEKEND. THE ECMWF SHOWS A MORE ZONAL
UPPER LEVEL FLOW WITH EMBEDDED STRONG SHORTWAVES AND A MORE ACTIVE
SOUTHERN STREAM WHICH WOULD INCREASE LOW-LEVEL MOISTURE FROM THE
GULF INTO THE CAROLINAS WITH A BETTER PRECIPITATION THREAT FROM
FRIDAY THROUGH THE WEEKEND. THE GFS KEEPS A PIECE OF THE SURFACE
RIDGE OVER OUR REGION LONGER WHILE AT 500 MB SHOWS THE UPPER LOW
CLOSING OFF BY LATER IN THE WEEKEND. THIS DELAYS ANY PRECIPITATION
INTO OUR REGION UNTIL LATE FRIDAY NIGHT OR SATURDAY. GIVEN THE
UNCERTAINTY...HAVE CONTINUED THE TREND FROM PREVIOUS FORECASTS BY
KEEPING SMALL POPS IN THE FORECAST FROM LATE THURSDAY NIGHT INTO
THE WEEKEND. WITH A VORTEX SPINNING OVER THE UPPER GREAT LAKES
AND STRONG NEGATIVE H5 HEIGHT ANOMALIES OVER MUCH OF THE EAST FOR
THE NEXT 6 TO 8 DAYS...WOULD EXPECT TEMPERATURES TO CONTINUE BELOW
NORMAL THROUGH THE EXTENDED PERIOD.
&&
.AVIATION /11Z MONDAY THROUGH FRIDAY/...
SHORT TERM /THROUGH TONIGHT/...
AS OF 715 AM MON...PREDOMINATE IFR CEILINGS CONTINUE ACROSS THE
TERMINALS WITH MOIST E/NE FLOW THIS MORNING. MEDIUM TO HIGH
CONFIDENCE THAT CEILINGS WILL CONTINUE AT IFR INTO THIS
AFTERNOON. WITH WEDGE IN PLACE IFR CIGS WILL LIKELY PERSIST INTO
EARLY THIS AFTERNOON...BASED ON FORECAST SOUNDINGS/GUIDANCE AND
SREF PROBS. LIGHT RAIN/DRIZZLE WILL BE POSSIBLE THROUGH MID
MORNING...MAINLY FOR PGV. STALLED FRONT TO THE SOUTH WILL LIFT
NORTH THROUGH THE AREA AS A WARM FRONT TODAY...WITH WINDS BECOMING
SOUTHERLY AND WITH CEILINGS LIKELY LIFTING TO VFR/MVFR. COLD FRONT
WILL APPROACH THE TERMINALS TONIGHT WITH CONDITIONS LIKELY
RETURNING TO SUB-VFR WITH SCT SHOWERS AND ISOLATED TSTMS...ANOTHER
ROUND OF IFR WILL BE POSSIBLE.
LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 305 AM MONDAY...EXPECT MVFR OR POSSIBLE IFR CONDITIONS TO
PREVAIL FOR THE FIRST HALF OF TUESDAY AS RAINFALL OCCURS AHEAD OF
COLD FRONT WHICH MOVES OFFSHORE EARLY TUESDAY AFTERNOON. VFR
CONDITIONS SHOULD PREVAIL WEDNESDAY AND THURSDAY. THERE WILL BE
SMALL RAINFALL CHANCES FRIDAY AND SOME BRIEF MVFR CONDITIONS MAY
OCCUR.
&&
.MARINE...
SHORT TERM /THROUGH TONIGHT/...
AS OF 1000 AM MONDAY...UPDATED FOR N-NE WINDS HOLDING INTO EARLY
AFTN WITH WEAK LOW PRES OFF HAT. WINDS WILL GRADUALLY DIMINISH AS
WAVES WEAKENS AND MOVES N-NE THIS AFTN...AND SRN WATERS WILL SEE
WINDS SHIFT TO SE-S LATE AFTN INTO EVENING AS FRONT GRADUALLY LIFTS
N. ALLOWED SCA TO EXPIRE AT 1000 AM FOR PAMLICO SOUND...BUT WILL
CONTINUE INTO LATE AFTN FOR NRN WATERS WITH SEAS STILL AROUND 6 FT.
/PREVIOUS DISCUSSION/
AS OF 715 AM MON...LATEST OBS SHOW NE WINDS 15-20KT WITH GUSTS TO
25KT...AND SEAS 4-7FT NORTH OF OCRACOKE...AND 3-5FT SOUTH. STALLED
FRONT TO THE SOUTH WILL LIFT NORTH THROUGH THE WATERS TODAY AS A
WARM FRONT. NE/E FLOW WILL DIMINISH LATE THIS MORNING AND EARLY
AFTERNOON...BECOMING SOUTHERLY THIS AFTERNOON AND EVENING. ONLY
CHANGE TO ONGOING HEADLINES WAS TO EXTEND SCA FOR PAMLICO SOUND
THROUGH 15Z THIS MORNING BASED ON LATEST OBS. WILL CONTINUE SCA
FOR CENTRAL AND NORTHERN WATERS FOR SEAS 4-7FT THROUGH LATE THIS
AFTERNOON/EARLY EVENING. S/SW FLOW WILL INCREASE TO 10-20KT
TONIGHT AHEAD OF APPROACHING COLD FRONT...THIS WILL RESULT IN SEAS
AGAIN BUILDING TO 6FT ON THE OUTER WATERS MAINLY SOUTH OF OREGON
INLET. ANOTHER SCA MAY BE NEEDED FOR WATERS AFTER 06Z TONIGHT.
LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 305 AM MONDAY...WITH COLD FRONT MOVING OFFSHORE EARLY
TUESDAY AFTERNOON...EXPECT A DECENT CAA SURGE WITH NW WINDS LIKELY
GUSTING TO AROUND 20 KNOTS AND SEAS BUILDING TO MINIMAL SMALL
CRAFT LEVELS OF 4 TO 6 FEET PER LATEST WAVEWATCH. THESE WINDS
SHOULD SUBSIDE AS WEAK HIGH PRESSURE BUILDS OVER THE AREA ON
WEDNESDAY...BUT KICK UP AGAIN TO THE 15 TO 20 KNOT RANGE BEHIND A
REINFORCING SHOT OF CANADIAN AIR ON WEDNESDAY NIGHT. WINDS AND
SEAS SHOULD SUBSIDE AGAIN BY LATE THURSDAY WITH AN OFFSHORE FLOW
LEADING TO SEAS OF 3 TO 5 FEET AND WINDS 15 KNOTS OR LESS FRIDAY
AND SATURDAY.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR AMZ150-
152-154.
SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR AMZ135.
&&
$$
SYNOPSIS...JBM/CQD
NEAR TERM...CQD/JBM
SHORT TERM...CQD
LONG TERM...CTC
AVIATION...CQD/CTC
MARINE...CQD/CTC/JBM
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1017 AM CDT MON MAR 18 2013
.DISCUSSION...
SOME BREAKS TRYING TO WORK INTO THE WEST AND SOUTHWEST FA BUT
OVERALL THINK IT WILL STAY MOSTLY CLOUDY IN THESE AREAS TODAY.
COULD BE SOME BLOWING SNOW STREAMERS TOO SO AM HESITANT TO BRING
ANY CLEARING IN TOO QUICKLY. HAVE RECEIVED A FEW REPORTS OF
FREEZING PCPN NEAR THE SFC LOW BUT TEMPS ARE DROPPING SO QUICKLY
WILL HOLD OFF ON ADDING ANY TO THE FORECAST. WIND SPEEDS HAVE
INCREASED ACROSS THE NORTHERN VALLEY FINALLY AND THIS IS CAUSING
WHITEOUT CONDITIONS UP AND DOWN THE VALLEY. ACTUAL VSBYS IN TOWN
ARE NOT AS BAD AND SOME ASOS/AWOS SENSORS ARE NOT REPRESENTATIVE
OF WHAT IT IS LIKE IN OPEN COUNTRY. REPORTS FROM KFAR DOWN THRU
KFFM ARE BELOW A QUARTER MILE IN OPEN COUNTRY. WITH WIND SPEEDS
STAYING UP TODAY NO PLANS TO CHANGE CURRENT HEADLINES THIS
MORNING. WILL HAVE TO KEEP ANY EYE ON THE WESTERN FRINGE AS THIS
AREA WILL SEE IMPROVING CONDITIONS WELL BEFORE THEY REACH THE RED
RIVER VALLEY.
&&
.AVIATION...
WITH SN AND BLSN CONDITIONS WILL CONTINUE TO BE VERY POOR THROUGH
THE REST OF THE DAY. VIS WILL BE DOWN TO 1/4SM AT TIMES FOR
KDVL...KGFK...AND KFAR WITH SLIGHTLY BETTER CONDITIONS AT THE
EASTERN TAF SITES. VIS AND CEILING SHOULD IMPROVE TO MVFR CONDITIONS
SHORTLY BEFORE 00Z THIS EVENING FOR THE WESTERN TAF SITES AND AFTER
00Z IN THE EAST. VFR CONDITIONS WILL HOLD OFF UNTIL LATE IN THE
PERIOD.
&&
.PREV DISCUSSION... /ISSUED 624 AM CDT MON MAR 18 2013/
DISCUSSION...
EXPANDED THE BLIZZARD WARNING TO INCLUDE ALL AREAS ALONG AND WEST
OF THE RED RIVER VALLEY. STRONG WINDS ACROSS THE SOUTHERN FA ARE
CREATING BLIZZARD CONDITIONS. FURTHER TO THE NORTH...WINDS ARE
INCREASING FROM COOPERSTOWN TO CANDO...WITH CURRENT SPEEDS AND/OR
GUSTS 30-35 KNOTS AND VSBY 1/4SM TO 1/2SM. GUIDANCE IS UNDER DOING
WIND SPEEDS...AND ALL MODELS INDICATE 925MB WIND SPEEDS INCREASING
THROUGH THE MORNING HOURS. THIS MEANS THAT MOST AREAS SHOULD HAVE
FREQUENT GUSTS TO AT LEAST 35 MPH. THERE IS A LOT OF FLUFFY SNOW
ACROSS THE NORTHERN FA AND IT SHOULD NOT TAKE MUCH FOR VERY LOW
VSBY IN BLOWING SNOW. PLUS...THE NORTHERN FA WILL HAVE -SN INTO
THE EARLY AFTERNOON HOURS THAT WILL ADD TO LOWERING VSBY.
PREV DISCUSSION... /ISSUED 348 AM CDT MON MAR 18 2013/
SHORT TERM (TODAY-TONIGHT)...
EXTENT OF BLIZZARD CONDITIONS WILL BE THE MAIN CHALLENGE. THE
STORM IS UNFOLDING PRETTY MUCH AS PLANNED WITH THE SURFACE LOW
JUST SOUTHWEST OF FARGO AS OF 08Z.
WARM AIR ADVECTION SNOWFALL AHEAD OF THIS SYSTEM WILL LIKELY HAVE
DROPPED 3 TO 6 INCHES OF SNOW ACROSS MOST AREAS BY SUNRISE.
ANOTHER 2-4 INCHES ARE EXPECTED ACROSS THE NE FA WITHIN THE MID-
LEVEL DEFORMATION ZONE...AND ANOTHER INCH OR TWO ELSEWHERE. TOTAL
SNOWFALL OF 6 TO 10 INCHES ACROSS THE NE FA...AND 4 TO 8 INCHES
ELSEWHERE IS STILL REASONABLE.
THE 00Z GEM AND ECMWF ARE SLIGHTLY SOUTH OF THE 00Z GFS AND NAM
WITH THE TRACK OF THE SURFACE LOW. THE 07Z RAP IS CLOSE TO THE
GFS/NAM TRACK...WHILE THE 06Z NAM HAS TRENDED SLIGHTLY SOUTH. THE
DISCREPANCY IS NOT HUGE...BUT COULD MEAN THE DIFFERENCE BETWEEN
WINTER STORM OR BLIZZARD CONDITIONS ACROSS THE NORTHERN RED RIVER
VALLEY. AS THIS SYSTEM PROPAGATES TO THE EAST/NORTHEAST...STRONG
LOW-LEVEL COLD AIR ADVECTION AND 40 KNOT 925MB WINDS WILL MOVE
INTO THE SOUTHERN FA...BASICALLY WHERE THE CURRENT BLIZZARD
WARNING IS ALREADY IN EFFECT...SO THIS IS GOOD. THE MAIN CHALLENGE
WILL BE LATER THIS MORNING INTO THE AFTERNOON HOURS. THE NORTHERN
SOLUTION...SUCH AS THE 07Z RAP BRINGS AN AREA OF LOW-LEVEL COLD
AIR ADVECTION ACROSS THE NORTHERN FA AROUND 18Z...AND INCREASES
925MB WINDS TO AROUND 40 KNOTS. THE SOUTHERN SOLUTION IS WEAKER
WITH THE COLD AIR ADVECTION...WITH 925MB WINDS AROUND 35 KNOTS.
THIS WILL LIKELY BE THE DIFFERENCE BETWEEN WINTER STORM AND
BLIZZARD CONDITIONS. 08Z SURFACE ANALYSIS WOULD ARGUE FOR THE
SOUTHERN SOLUTION GIVEN STRONGEST PRESSURE FALLS INTO THE BEMIDJI
AREA. FOR THIS REASON WILL MAKE NO CHANGES TO THE HEADLINES...BUT
WILL MONITOR INCOMING OBSERVATIONS AND MODEL GUIDANCE AS AN
UPGRADE TO A BLIZZARD WARNING ACROSS THE NORTHERN RED RIVER VALLEY
IS NOT OUT OF THE QUESTION.
LONG TERM (TUESDAY-SUNDAY NIGHT)...
AFTER THE LAST OF THE CURRENT WINTER STORM MOVES OUT OF THE REGION
LATER TONIGHT...TUESDAY TROUGH THE WORK WEEK AND INTO NEXT WEEKEND
WILL BE QUIET WEATHER-WISE. NORTHWEST FLOW ALOFT ON TUESDAY WILL
BECOME WEAK AND ILL-DEFINED BY THURSDAY AS INTERMOUNTAIN RIDGE
WEAKENS AND MOVES INTO THE CENTRAL PLAINS. AT THE SURFACE...HIGH
PRESSURE WILL DOMINATE THE NORTHERN PLAINS FOR MUCH OF THE WEEK.
BEST CHANCE FOR PERSISTENT CLOUD COVER WILL BE ACROSS NORTHWEST MN
WITH MORE SUN THAN CLOUDS ALONG AND WEST OF THE VALLEY. THERE IS A
SLIGHT CHANCE FOR SNOW SHOWERS FRIDAY AND FRIDAY NIGHT ACROSS THE
WEST IN RESPONSE TO MID-LEVEL WARM ADVECTION. OTHERWISE...EXPECT DRY
CONDITIONS. TEMPERATURES WILL REMAIN WELL BELOW MID-MARCH NORMALS
THROUGH THURSDAY...THEN SLOWLY INCREASING EACH DAY FRIDAY INTO THE
WEEKEND WITH THE APPROACHING RIDGE. CURRENT FORECAST SHOWS DAYTIME
HIGHS APPROACHING THE FREEZING MARK SATURDAY INTO SUNDAY.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...BLIZZARD WARNING UNTIL 7 PM CDT THIS EVENING FOR NDZ006>008-
014>016-024-026>030-038-039-049-052>054.
MN...BLIZZARD WARNING UNTIL 7 PM CDT THIS EVENING FOR MNZ001>004-007-
029-030-040.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR MNZ005-006-
008-009-013>017-022>024-027-028-031-032.
&&
$$
GODON/JR/JK
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
624 AM CDT MON MAR 18 2013
.DISCUSSION...
EXPANDED THE BLIZZARD WARNING TO INCLUDE ALL AREAS ALONG AND WEST
OF THE RED RIVER VALLEY. STRONG WINDS ACROSS THE SOUTHERN FA ARE
CREATING BLIZZARD CONDITIONS. FURTHER TO THE NORTH...WINDS ARE
INCREASING FROM COOPERSTOWN TO CANDO...WITH CURRENT SPEEDS AND/OR
GUSTS 30-35 KNOTS AND VSBY 1/4SM TO 1/2SM. GUIDANCE IS UNDER DOING
WIND SPEEDS...AND ALL MODELS INDICATE 925MB WIND SPEEDS INCREASING
THROUGH THE MORNING HOURS. THIS MEANS THAT MOST AREAS SHOULD HAVE
FREQUENT GUSTS TO AT LEAST 35 MPH. THERE IS A LOT OF FLUFFY SNOW
ACROSS THE NORTHERN FA AND IT SHOULD NOT TAKE MUCH FOR VERY LOW
VSBY IN BLOWING SNOW. PLUS...THE NORTHERN FA WILL HAVE -SN INTO
THE EARLY AFTERNOON HOURS THAT WILL ADD TO LOWERING VSBY.
&&
.AVIATION...
MVFR/IFR CEILINGS TO PERSIST MOST OF THE DAY AS LIGHT TO MODERATE
SNOW SLOWLY MOVES FROM WEST TO EAST. GUSTY SOUTHEAST WIND WILL
ABRUPTLY SHIFT TO THE NORTHWEST AS SURFACE LOW CURRENTLY NEAR KFAR
EJECTS TO THE NORTH AND EAST THROUGH THE MORNING. GUSTS TO 35 KTS
ARE POSSIBLE IN NORTHWEST FLOW...CREATING CONSIDERABLE BLOWING/
DRIFTING SNOW AND VISIBILITIES DOWN TO ONE HALF MILE OR LESS AT ALL
TAF SITES. MULTIPLE AMENDMENTS ARE POSSIBLE...BUT CONDITIONS SHOULD
VERY SLOWLY IMPROVE THIS EVENING AND OVERNIGHT.
&&
.PREV DISCUSSION... /ISSUED 348 AM CDT MON MAR 18 2013/
SHORT TERM (TODAY-TONIGHT)...
EXTENT OF BLIZZARD CONDITIONS WILL BE THE MAIN CHALLENGE. THE
STORM IS UNFOLDING PRETTY MUCH AS PLANNED WITH THE SURFACE LOW
JUST SOUTHWEST OF FARGO AS OF 08Z.
WARM AIR ADVECTION SNOWFALL AHEAD OF THIS SYSTEM WILL LIKELY HAVE
DROPPED 3 TO 6 INCHES OF SNOW ACROSS MOST AREAS BY SUNRISE.
ANOTHER 2-4 INCHES ARE EXPECTED ACROSS THE NE FA WITHIN THE MID-
LEVEL DEFORMATION ZONE...AND ANOTHER INCH OR TWO ELSEWHERE. TOTAL
SNOWFALL OF 6 TO 10 INCHES ACROSS THE NE FA...AND 4 TO 8 INCHES
ELSEWHERE IS STILL REASONABLE.
THE 00Z GEM AND ECMWF ARE SLIGHTLY SOUTH OF THE 00Z GFS AND NAM
WITH THE TRACK OF THE SURFACE LOW. THE 07Z RAP IS CLOSE TO THE
GFS/NAM TRACK...WHILE THE 06Z NAM HAS TRENDED SLIGHTLY SOUTH. THE
DISCREPANCY IS NOT HUGE...BUT COULD MEAN THE DIFFERENCE BETWEEN
WINTER STORM OR BLIZZARD CONDITIONS ACROSS THE NORTHERN RED RIVER
VALLEY. AS THIS SYSTEM PROPAGATES TO THE EAST/NORTHEAST...STRONG
LOW-LEVEL COLD AIR ADVECTION AND 40 KNOT 925MB WINDS WILL MOVE
INTO THE SOUTHERN FA...BASICALLY WHERE THE CURRENT BLIZZARD
WARNING IS ALREADY IN EFFECT...SO THIS IS GOOD. THE MAIN CHALLENGE
WILL BE LATER THIS MORNING INTO THE AFTERNOON HOURS. THE NORTHERN
SOLUTION...SUCH AS THE 07Z RAP BRINGS AN AREA OF LOW-LEVEL COLD
AIR ADVECTION ACROSS THE NORTHERN FA AROUND 18Z...AND INCREASES
925MB WINDS TO AROUND 40 KNOTS. THE SOUTHERN SOLUTION IS WEAKER
WITH THE COLD AIR ADVECTION...WITH 925MB WINDS AROUND 35 KNOTS.
THIS WILL LIKELY BE THE DIFFERENCE BETWEEN WINTER STORM AND
BLIZZARD CONDITIONS. 08Z SURFACE ANALYSIS WOULD ARGUE FOR THE
SOUTHERN SOLUTION GIVEN STRONGEST PRESSURE FALLS INTO THE BEMIDJI
AREA. FOR THIS REASON WILL MAKE NO CHANGES TO THE HEADLINES...BUT
WILL MONITOR INCOMING OBSERVATIONS AND MODEL GUIDANCE AS AN
UPGRADE TO A BLIZZARD WARNING ACROSS THE NORTHERN RED RIVER VALLEY
IS NOT OUT OF THE QUESTION.
LONG TERM (TUESDAY-SUNDAY NIGHT)...
AFTER THE LAST OF THE CURRENT WINTER STORM MOVES OUT OF THE REGION
LATER TONIGHT...TUESDAY TROUGH THE WORK WEEK AND INTO NEXT WEEKEND
WILL BE QUIET WEATHER-WISE. NORTHWEST FLOW ALOFT ON TUESDAY WILL
BECOME WEAK AND ILL-DEFINED BY THURSDAY AS INTERMOUNTAIN RIDGE
WEAKENS AND MOVES INTO THE CENTRAL PLAINS. AT THE SURFACE...HIGH
PRESSURE WILL DOMINATE THE NORTHERN PLAINS FOR MUCH OF THE WEEK.
BEST CHANCE FOR PERSISTENT CLOUD COVER WILL BE ACROSS NORTHWEST MN
WITH MORE SUN THAN CLOUDS ALONG AND WEST OF THE VALLEY. THERE IS A
SLIGHT CHANCE FOR SNOW SHOWERS FRIDAY AND FRIDAY NIGHT ACROSS THE
WEST IN RESPONSE TO MID-LEVEL WARM ADVECTION. OTHERWISE...EXPECT DRY
CONDITIONS. TEMPERATURES WILL REMAIN WELL BELOW MID-MARCH NORMALS
THROUGH THURSDAY...THEN SLOWLY INCREASING EACH DAY FRIDAY INTO THE
WEEKEND WITH THE APPROACHING RIDGE. CURRENT FORECAST SHOWS DAYTIME
HIGHS APPROACHING THE FREEZING MARK SATURDAY INTO SUNDAY.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...BLIZZARD WARNING UNTIL 7 PM CDT THIS EVENING FOR NDZ006>008-
014>016-024-026>030-038-039-049-052>054.
MN...BLIZZARD WARNING UNTIL 7 PM CDT THIS EVENING FOR MNZ001>004-007-
029-030-040.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR MNZ005-006-
008-009-013>017-022>024-027-028-031-032.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1031 AM EDT MON MAR 18 2013
.SYNOPSIS...
WEDGE OF HIGH PRESSURE WILL REMAIN IN PLACE THROUGH THIS EVENING.
WARM FRONT TO THE SOUTH FINALLY SLIDES NORTHEAST TONIGHT WHILE THE
COLD FRONT FOLLOWS CLOSELY BEHIND OVERNIGHT. HIGH PRESSURE WILL
MOVE IN BY TUESDAY AFTERNOON...WITH AN UPPER DISTURBANCE EXPECTED
TO AFFECT THE MOUNTAINS WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM EDT MONDAY...
12Z RNK SOUNDING SHOWED A 1.5 DEGREE C WARM NOSE ABV THE SFC...BUT
NO SNOW CRYSTAL GROWTH ZONE. WITH 14Z SFC TEMPS STILL BELOW
FREEZING ACROSS MANY MOUNTAIN LOCATIONS...LIGHT FREEZING DRIZZLE
IS STILL POSSIBLE THROUGH THE EARLY AFTERNOON...SO WINTER WEATHER
ADVISORY WILL CONTINUE. SFC WEDGE WILL PERSIST INTO THE
AFTERNOON...SO LOWERED HIGH TEMPS BY A FEW DEGREES
THE EXCEPTION WAS IN THE FAR WEST...WHERE CLEARING HAS TAKEN PLACE
ACROSS PORTIONS OF THE MOUNTAIN EMPIRE REGION. A FEW RUMBLES OF
THUNDER ARE NOT OUT OF THE QUESTION IN THIS REGION WHICH WILL
DESTABILIZE THIS AFTERNOON.
OTHERWISE...FOLLOWED THE 12Z RAP WITH TIMING OF PRECIP THIS
AFTERNOON.
THE FRONT MOVES IN TONIGHT AND WILL BE SEEING BEST THREAT OF RAIN
IN THE MTNS WITH MODELS SHOWING SOME JUMP IN THE HIGHER QPF ACROSS
THE PIEDMONT LEAVING THE MIDDLE PORTION OF THE CWA WITH LESS.
ALTHOUGH THIS IS A POSSIBILITY THINK POPS IN THE LIKELY TO
CATEGORICAL RANGE IS BEST. KEPT ISOLATED THUNDER IN THE FAR WEST
THIS EVENING OUTSIDE THE WEDGE.
THE COLDER AIR WILL BE SWINGING IN BEHIND THE FRONT LATE IN THE
HIGHER MOUNTAINS WITH SNOW SHOWERS POSSIBLE ON THE WRN SLOPES. DRY
SLOT ARRIVING WILL DRY THINGS OUT FAST BY DAWN EAST OF THE MTNS. LOW
RANGE FROM THE UPPER 20S HIGHER ELEVATIONS IN THE WEST WITH MOST
AREAS IN THE 30S...WHILE THE FAR EAST STAY STEADY IN THE LOWER
40S...WITH WEDGE HOLDING UNTIL COLD FROPA. TEMPS ACTUALLY MAY WARM
IN THE SMALL WINDOW BETWEEN WEDGE BREAKING AND FROPA AS COLDER AIR
WILL BE DELAYED.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
AS OF 415 AM EDT MONDAY...
A COLD FRONT WILL BE EXITING THE EASTERN PORTION OF THE BLACKSBURG
FORECAST AREA AROUND DAYBREAK TUESDAY...WITH ANY LINGERING SHOWERS
OVER EASTERN PIEDMONT COUNTIES TO END BY MID MORNING...FOLLOWED BY
CLEARING SKIES AS DOWNSLOPING INCREASES EAST OF THE BLUE RIDGE.
GOOD INSOLATION AND COMPRESSIONAL WARMING SHOULD OFFSET CONTRIBUTION
OF COLD ADVECTION ACROSS THE PIEDMONT THROUGH MUCH OF THE DAY...
SUPPORTING TEMPERATURES REACHING THE LOWER TO MID 60S. FURTHER
WEST...UPSLOPING CLOUDS AND ARRIVAL OF DEEPER COLDER AIR SHOULD
LIMIT DAYTIME HIGHS TO THE 30S ACROSS THE HIGHEST WEST FACING FLANKS
OF THE APPALACHIANS.
THE UPPER AIR PATTERN DOES NOT CHANGE MUCH THROUGH MID WEEK WITH
RIDGE IN THE WESTERN CONUS AND TROF IN THE EAST. THIS SUPPORTS A
TREND BACK TOWARD COLDER THAN NORMAL TEMPERATURES ACROSS OUR AREA.
NORTHWEST FLOW WILL PERSIST RIGHT ON INTO WEDNESDAY WITH 85H TEMPS
BLOW FREEZING. FOR THE MOST PART...THE FLOW IS DRY. THERE IS AN
UPPER LEVEL DISTURBANCE WHICH IS PROGGED TO COME THROUGH DURING THE
DAY WEDNESDAY. THIS FEATURE MAY BRING SNOW SHOWERS AND
FLURRIES...BUT MORE IMPORTANTLY A REINFORCING SHOT OF COLD AIR THAT
WILL SEND TEMPERATURES WELL BELOW NORMAL WEDNESDAY NIGHT INTO
THURSDAY AS 85H TEMPERATURES TEST M14 DEG C.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 400 PM EDT SUNDAY...
A BLOCKY HEMISPHERIC CIRCULATION IS ADVERTISED BY THE LONG RANGE
MODELS THROUGH NEXT WEEKEND...MARKED BY THREE STRONG POSITIVE HEIGHT
ANOMALIES. THE FIRST IS THROUGH THE BERING SEA WHILE THE SECOND AND
THIRD MERGE BETWEEN THE NORTH POLE AND THE DAVIS STRAIT.
TELECONNECTIONS FROM EACH AREA SUPPORT RIDGING JUST OFF THE WEST
COAST WITH BROAD TROUGHING FROM THE CENTRAL CONUS EASTWARD. THIS
VERY NEGATIVE AO PATTERN SUPPORTS BELOW NORMAL TEMPERATURES EAST OF
THE ROCKIES WITH THE POLAR FRONT ALONG THE GULF COAST.
WEATHER CHALLENGE DURING THIS TIME FRAME IS WHETHER ANY SORT OF
CYCLOGENESIS CAN TAKE PLACE ALONG THIS POLAR FRONT WHICH WILL BE
SITUATED SOUTH OF OUR FCST AREA...AND IF SO CAN ANY OF THIS ENERGY
GAIN ANY LATITUDE PER STRONG WESTERLIES WITHIN THE COLD TROUGH WHICH
WILL BE DIRECTLY OVERHEAD DURING THE PERIOD. FORECAST
SPREAD/UNCERTAINTY AND RUN-RUN CONTINUITY INCREASES SIGNIFICANTLY
HEADING INTO NEXT WEEKEND. RECENT ECMWF/ECMWF ENSEMBLES IN
PARTICULAR HAVE OFFERED MORE SUPPRESSED SOLUTIONS THAN RECENT
GFS/GEFS. THE GFS RUNS INSTEAD OFFER A DEEPER SERN US/MID-ATLC
COASTAL STORM. ENSEMBLES ARE MIXED/IN THE MIDDLE BUT OVERALL FAVOR
A SOLUTION WITH EMPHASIS OVER THE SRN/SERN US...THAT SOME SORT OF
SYSTEM WILL GET GENERATED. SINCE THERE IS NO SOLID CONSENSUS ON
HOW FAR NORTH THIS SYSTEM WILL TRACK...WILL ADVERTISE CHC POPS FOR
THE ENTIRE CWA...WITH FOCUS ON THE SUNDAY TIME FRAME...DAY 7. AS
LUCK WOULD HAVE IT...WINTER ISN`T OVER...SO PTYPE CHALLENGE WILL
ALSO COME INTO PLAY IF THE SYSTEM SPREADS ANY MOISTURE THIS FAR
NORTH.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
AS OF 740 AM EDT MONDAY...
NOT TOO MUCH CHANGE TO THE PREVIOUS TERMINALS ISSED AT 06Z. NOT
GOING TO BE A GOOD DAY TO FLY WITH CIGS STAYING IFR OR WORSE.
EXCEPTION MAY BE SOME BREAKS AT BLF AS THEY MAY SCOUR OUT THE
WEDGE SOME THIS AFTERNOON. NOT FAR FROM BLF IS CLEAR SKIES ABOUT
10 NM WEST OF THE AIRPORT...SO WILL BE CLOSE. CANNOT RULE OUT THEN
SCATTERING OUT FOR A A PERIOD OF TIME THIS AFTERNOON.
GOING THROUGH TONIGHT THE FRONT PASSES THE BLF-LWB-BCB AREA
BETWEEN 06Z-09Z AND EAST OF DAN/LYH BY 11Z. THE WEDGE BREAKS WHERE
CIGS WILL RISE TO MVFR AS THE FRONT MOVES ACROSS.
TUESDAY THROUGH FRIDAY WILL BE MUCH IMPROVED ACROSS THE REGION. SOME
UPSLOPE SNOW SHOWERS ARE POSSIBLE AT BLF WEDNESDAY AFTERNOON AND
EVENING. THE WINDS WILL PICK UP DRAMATICALLY ON TUESDAY AND
WEDNESDAY ACROSS THE WEST...EXPECT 25-30KT GUSTS AT TIMES FOR
BLF/BCB/LWB/ROA. DESPITE THE WINDS VFR CONDITIONS ARE EXPECTED FOR
THE VAST MAJORITY OF THE REMAINING TAF PERIOD.
&&
.FIRE WEATHER...
AS OF 455 AM EDT MONDAY...
STRONG AND GUSTY WINDS FROM THE WEST WILL OVERSPREAD THE ENTIRE
REGION FOLLOWING THE PASSAGE OF A COLD ON TUESDAY. EAST OF THE
BLUE RIDGE...RELATIVE HUMIDITIES ARE EXPECTED TO FALL TO AROUND 20
PERCENT BY AFTERNOON...AND COUPLED WITH THE EXPECTED GUSTY
WINDS...MAY RESULT IN AN ELEVATED FIRE DANGER THREAT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR
VAZ018>020-023-024-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR
WVZ045.
&&
$$
SYNOPSIS...WP
NEAR TERM...PH
SHORT TERM...PM/WERT
LONG TERM...PM
AVIATION...CF/WP
FIRE WEATHER...WERT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
715 AM CDT MON MAR 18 2013
.SHORT TERM...UPDATED
715 AM CDT MON MAR 18 2013
QUICK UPDATE TO FORECAST TO EXPAND WINTER WEATHER ADVISORY FOR THE
REST OF THE FORECAST AREA. EXPECTING 2 TO 3 INCHES FOR THE
ADDITIONAL NORTHEAST IA/SOUTHWEST WI COUNTIES. BLOWING WILL BE AN
ISSUE BY LATE AFTERNOON...ESPECIALLY ACROSS THE OPEN SPACES OF
NORTHEAST IOWA AND AREA RIDGE-TOPS. SEE PREVIOUS SHORT TERM FORECAST
DISCUSSION FOR THE WHAT/S AND WHY/S OF TODAY/S STORM SYSTEM.
.LONG TERM...THURSDAY THROUGH SUNDAY
309 AM CDT MON MAR 18 2013
THE LONG TERM PERIOD LOOKS TO BE FAIRLY QUIET AS WEAK HIGH PRESSURE
PREVAILS. ALSO LOOKS LIKE A SLOW MODERATION IN TEMPERATURES BUT
STILL REMAINING BELOW NORMAL.
&&
.AVIATION...
630 AM CDT SUN MAR 17 2013
A COLD FRONT WILL SWEEP WEST-EAST ACROSS THE REGION TODAY...WITH A
BAND OF SN RIDING OUT AHEAD OF IT. SNOW WILL BE ON KRST BY 12Z...AND
BETWEEN 13-14Z FOR KLSE. THERE WILL BE 1-2SM REDUCTIONS IN THE
SN...AND SNOWFALL RATES OF UP TO 1 INCH/HOUR WILL BE POSSIBLE FOR A
SHORT PERIOD. THE BAND WILL MOVE ACROSS EACH SITE IN ABOUT 3
HOURS...BUT COULD BRING A QUICK 2 TO 3 INCHES. MEANWHILE...THERE IS
AN AREA OF -SN THAT CONTINUES TO DEVELOP OVER EASTERN IOWA...MOVING
NORTHEAST. VSBYS ARE MVFR WITH THIS SNOW...BUT SOME HINTS IN THE
MESO MODELS THAT THIS WILL INTENSIFY BY MID MORNING. UNSURE WHETHER
THIS WILL HAVE A CHANCE TO IMPACT KLSE...WITH CURRENT TRAJECTORIES
SUGGESTING IT COULD STAY JUST EAST. IFR TO LIFR CIGS WILL BE THE
RULE INTO TONIGHT. IT SHOULD BE NOTED THAT BUFKIT SOUNDINGS CONTINUE
TO HINT AT A FREEZING DRIZZLE POTENTIAL BEHIND THE MAIN SNOW BAND.
LATEST SFC OBS POST THE CURRENT BAND INDICATE THAT THIS MIGHT BE
TRUE. WILL ADD A MENTION AT KRST. ALSO LATEST HRRR AND NAM12 MESO
MODELS HINT AT A SECOND BAND DEVELOPING IN THE WAKE OF THIS FIRST
BAND. WILL TRY AND TREND THIS POTENTIAL INTO KLSE...NOT SURE THERE
WOULD BE A BIG ENOUGH BREAK BETWEEN THE TWO AT KRST TO REFINE
TIMING.
WINDS WILL INCREASE SHARPLY BEHIND THE FRONT...BY 17Z FOR KRST AND
20Z AT KLSE. GUSTS UP TO 35 KTS ARE LIKELY FOR KRST. THE WIND
WILL MAKE BLSN A FACTOR...AND THERE SHOULD BE SOME REDUCTIONS IN
VSBYS AT KRST AS A RESULT...PERHAPS PERSISTING INTO THE EVENING. AT
KLSE...HARDER FOR BLSN TO HAVE AS BIG AN IMPACT GIVEN
LOCATION/TERRAIN...BUT SOME VSBY RESTRICTIONS CAN/T BE RULED OUT.
WINDS WILL STAY UP ALL NIGHT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
712 AM CDT MON MAR 18 2013
WI...WINTER WEATHER ADVISORY UNTIL 1 AM CDT TUESDAY FOR WIZ017-029-
032>034-041>044-053>055-061.
MN...WINTER WEATHER ADVISORY UNTIL 1 AM CDT TUESDAY FOR MNZ079-
086>088-094>096.
IA...WINTER WEATHER ADVISORY UNTIL 1 AM CDT TUESDAY FOR IAZ008>011-
018-019-029-030.
&&
$$
SHORT TERM...RIECK
LONG TERM....DAS
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
630 AM CDT MON MAR 18 2013
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
309 AM CDT MON MAR 18 2013
MAIN CONCERN IS STRONG COLD FRONT/ASSOCIATED SNOWFALL PUSHING
THROUGH THE AREA TODAY. BLOWING SNOW A CONCERN FOR PORTIONS OF THE
AREA THIS AFTERNOON.
AT 3 AM...WATER VAPOR IMAGERY SHOWS A VIGOROUS MID-LEVEL TROUGH
EXTENDING FROM SOUTHEAST SASKATCHEWAN CANADA THROUGH THE WESTERN
DAKOTAS INTO THE PANHANDLE OF NEBRASKA. AT THE SURFACE...A 999MB LOW
WAS LOCATED EAST OF BISMARK ND WITH A COLD FRONT EXTENDING SOUTH
THROUGH EASTERN SD/NEBRASKA. RADAR MOSAIC HAS A BAND OF LIGHT TO
MODERATE SNOW AHEAD OF THE LOW AND COLD FRONT EXTENDING FROM
NORTHEAST MN THROUGH WESTERN IA. AHEAD OF THIS MAIN BAND OF
SNOW...THERE WAS AN AREA OF MIXED RAIN/SNOW OVER CENTRAL IA MOVING
NORTHEAST TOWARD THE AREA.
FORECAST LOOKS ON TRACK FOR THIS COLD FRONT AND BAND OF SNOW TO
TRACK ACROSS THE AREA THIS MORNING WITH THE BULK OF ACCUMULATING
SNOW EXITING THE AREA BY AFTERNOON. THROUGH THE AFTERNOON INTO THE
EVENING...SCATTERED SNOW SHOWERS EXPECTED TO LINGER. IN
ADDITION...SOME LIGHT DRIZZLE/FREEZING DRIZZLE MAY BE SEEN ON
OCCASION AS LOSS OF ICE OCCURS IN THE CLOUDS. STILL LOOKING AT
SNOWFALL TOTALS IN THE 2 TO 5 INCH RANGE ACROSS THE AREA WITH
HIGHEST AMOUNTS EXPECTED NORTH OF THE I-90 CORRIDOR. HEIGHTENED
CONCERN WILL BE THIS AFTERNOON BEHIND THE FRONT AS GUSTY
WEST/NORTHWEST WINDS OVERSPREAD THE AREA. WIND SPEEDS EXPECTED TO
INCREASE INTO THE 20-25 MPH RANGE WITH GUSTS IN THE 30-40 MPH ACROSS
THE OPEN WIND-PRONE AREAS OF SOUTHEAST MN/NORTHEAST IA. HELD OFF ON
WINTER STORM WARNING ACROSS THAT AREA FOR NOW BASED ON THE
POSSIBILITY OF SOME FREEZING DRIZZLE/DRIZZLE MIXING IN WITH THE SNOW
AND THEREFORE PUTTING MORE LIQUID CONTENT INTO THE SNOW...AND
THEREBY POSSIBLY LIMITING BLOWING SNOW. BASED ON ALL THIS...HAVE
DECIDED TO STICK WITH CURRENT WINTER WEATHER ADVISORY HEADLINE VALID
UNTIL 1 AM TUESDAY GIVEN THE SNOW AMOUNTS AND AREAS OF BLOWING SNOW.
FOR TUESDAY THROUGH WEDNESDAY NIGHT...COLDER NORTHWEST FLOW ALOFT
WITH EMBEDDED SHORTWAVE TROUGH WILL PREVAIL. THIS WILL YIELD
PERIODIC FLURRIES ACROSS THE AREA. OTHERWISE...TEMPERATURES TUESDAY
AND WEDNESDAY WILL RUN WELL BELOW NORMAL WITH HIGHS TUESDAY IN THE
20S AND IN THE UPPER TEENS/LOWER 20S ON WEDNESDAY. OVERNIGHT LOWS
TUESDAY NIGHT/WEDNESDAY NIGHT EXPECTED TO BE IN THE SINGLE DIGITS
ABOVE ZERO.
.LONG TERM...THURSDAY THROUGH SUNDAY
309 AM CDT MON MAR 18 2013
THE LONG TERM PERIOD LOOKS TO BE FAIRLY QUIET AS WEAK HIGH PRESSURE
PREVAILS. ALSO LOOKS LIKE A SLOW MODERATION IN TEMPERATURES BUT
STILL REMAINING BELOW NORMAL.
&&
.AVIATION...
630 AM CDT SUN MAR 17 2013
A COLD FRONT WILL SWEEP WEST-EAST ACROSS THE REGION TODAY...WITH A
BAND OF SN RIDING OUT AHEAD OF IT. SNOW WILL BE ON KRST BY 12Z...AND
BETWEEN 13-14Z FOR KLSE. THERE WILL BE 1-2SM REDUCTIONS IN THE
SN...AND SNOWFALL RATES OF UP TO 1 INCH/HOUR WILL BE POSSIBLE FOR A
SHORT PERIOD. THE BAND WILL MOVE ACROSS EACH SITE IN ABOUT 3
HOURS...BUT COULD BRING A QUICK 2 TO 3 INCHES. MEANWHILE...THERE IS
AN AREA OF -SN THAT CONTINUES TO DEVELOP OVER EASTERN IOWA...MOVING
NORTHEAST. VSBYS ARE MVFR WITH THIS SNOW...BUT SOME HINTS IN THE
MESO MODELS THAT THIS WILL INTENSIFY BY MID MORNING. UNSURE WHETHER
THIS WILL HAVE A CHANCE TO IMPACT KLSE...WITH CURRENT TRAJECTORIES
SUGGESTING IT COULD STAY JUST EAST. IFR TO LIFR CIGS WILL BE THE
RULE INTO TONIGHT. IT SHOULD BE NOTED THAT BUFKIT SOUNDINGS CONTINUE
TO HINT AT A FREEZING DRIZZLE POTENTIAL BEHIND THE MAIN SNOW BAND.
LATEST SFC OBS POST THE CURRENT BAND INDICATE THAT THIS MIGHT BE
TRUE. WILL ADD A MENTION AT KRST. ALSO LATEST HRRR AND NAM12 MESO
MODELS HINT AT A SECOND BAND DEVELOPING IN THE WAKE OF THIS FIRST
BAND. WILL TRY AND TREND THIS POTENTIAL INTO KLSE...NOT SURE THERE
WOULD BE A BIG ENOUGH BREAK BETWEEN THE TWO AT KRST TO REFINE
TIMING.
WINDS WILL INCREASE SHARPLY BEHIND THE FRONT...BY 17Z FOR KRST AND
20Z AT KLSE. GUSTS UP TO 35 KTS ARE LIKELY FOR KRST. THE WIND
WILL MAKE BLSN A FACTOR...AND THERE SHOULD BE SOME REDUCTIONS IN
VSBYS AT KRST AS A RESULT...PERHAPS PERSISTING INTO THE EVENING. AT
KLSE...HARDER FOR BLSN TO HAVE AS BIG AN IMPACT GIVEN
LOCATION/TERRAIN...BUT SOME VSBY RESTRICTIONS CAN/T BE RULED OUT.
WINDS WILL STAY UP ALL NIGHT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
309 AM CDT MON MAR 18 2013
WI...WINTER WEATHER ADVISORY UNTIL 1 AM CDT TUESDAY FOR
WIZ017-029-032>034-041-042-053.
WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 1 AM CDT
TUESDAY FOR WIZ043-044.
MN...WINTER WEATHER ADVISORY UNTIL 1 AM CDT TUESDAY FOR MNZ079-
086>088-094>096.
IA...WINTER WEATHER ADVISORY UNTIL 1 AM CDT TUESDAY FOR IAZ008>010-
018-019.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
343 PM MDT MON MAR 18 2013
.SHORT TERM...WEB CAMS CONTINUE TO SHOW AREAS OF LIGHT SNOW ALONG
THE CONTINENTAL DIVIDE OF SUMMIT AND GRAND COUNTIES...MAINLY WEST
AND NORTH FACING SLOPES. SOME SNOW ALSO OCCURRING OVER THE PARK
AND GORE RANGES OF WESTERN JACKSON COUNTY. THE SNOW HAS BEEN
SHOWING SOME SIGNS OF DECREASING. IN ADDITION...GUSTY WINDS WERE
OCCURRING ALONG THE FOOTHILLS AND ACROSS THE PLAINS WITH SOME
GUSTS AROUND 40 MPH. FOR TONIGHT...STRONG NORTHWEST FLOW ALOFT TO
CONTINUE. MODEL CROSS SECTIONS SHOW DRIER AIR MOVING INTO THE
MOUNTAINS THIS EVENING...SHOULD SEE SNOW CONTINUE TO DECREASE AND
COME TO AN END BY MIDNIGHT. MODELS CONTINUE TO INDICATE THE
DEVELOPMENT OF A STABLE LAYER NEAR MOUNTAIN TOP OVERNIGHT WHICH
WILL HELP WITH THE DEVELOPMENT OF A MOUNTAIN WAVE. THUS...WINDS TO
INCREASE IN AND NEAR FOOTHILLS AFTER MIDNIGHT. LATEST RAP CROSS
SECTIONS SHOWING CROSS MOUNTAIN FLOW INCREASING TO AROUND 50 KTS
AT MOUNTAIN TOP. SOME GUSTS AROUND 60 MPH A POSSIBILITY IN THE
WINDY LOCATIONS. ACROSS PLAINS...WINDS TO DECREASE DURING THE
EVENING ONCE THE AIRMASS STABILIZES. ON TUESDAY...A WEAKER
NORTHWEST FLOW ALOFT WILL BE OVER THE REGION. WINDS SHOULD
DECREASE THOUGH WILL BE A BIT GUSTY AT TIMES ACROSS THE RIDGES AND
ALONG THE FOOTHILLS. MIXING WILL ALSO ALLOW GUSTY WINDS TO OCCUR
NEAR THE WYOMING AND NEBRASKA BORDERS DURING THE AFTERNOON.
AIRMASS TO BE DRIER AND SLIGHTLY WARMER WITH ANY MOISTURE ABOVE
MOUNTAIN TOP. TEMPERATURES SHOULD WARM INTO THE 50S ACROSS THE
PLAINS. SOME AREAS MAY BE SLIGHTLY COOLER DUE TO LESS WIND.
.LONG TERM...UPPER LEVEL RIDGE WILL BUILD EASTWARD ACROSS THE
CENTRAL ROCKIES TUESDAY NIGHT AND WEDNESDAY WITH DRY CONDITIONS.
HOWEVER...BY LATE WEDNESDAY...ENOUGH MOISTURE AND INSTABILITY
SHOULD BE ENOUGH TO PRODUCE SHOWERS IN THE MOUNTAINS. THE MAIN
SHOT OF Q-G LIFT AND MOISTURE INCREASE IS STILL SLATED TO HOLD OFF
UNTIL THURSDAY INTO THURSDAY EVENING. AT THIS TIME...THE
COMBINATION OF LIFT AND INSTABILITY SHOULD PRODUCE NUMEROUS
SHOWERS IN THE HIGH COUNTRY WITH LIGHT TO MODERATE SNOW
ACCUMULATIONS. ON THE PLAINS...RAIN SHOWERS ARE EXPECTED TO
DEVELOP BY THURSDAY AFTERNOON AND SPREAD EAST ACROSS THE PLAINS IN
THE EVENING WITH THE BEST LIFT. TEMPERATURES TURN COLD ENOUGH TO
HELP CHANGE RAIN SHOWERS OVER TO SNOW SHOWERS...BUT ANY
ACCUMULATION ON THE PLAINS MAY BE LIMITED OR NIL IF THE COLD AIR
LAGS SLIGHTLY BEHIND THE BETTER PRECIPITION AS CURRENTLY INDICATED
BY MOST MODEL RUNS.
BY FRIDAY INTO SATURDAY...COLD AIR BECOMES MORE FIRMLY ENTRENCHED
ACROSS THE FORECAST AREA. MODELS HAVE SEEM TO COME AROUND TO A
FAIRLY UNIFORM SOLUTION BRINGING ANOTHER UPPER LEVEL DISTURBANCE
AROUND THE BASE OF THE TROUGH FOR FRIDAY NIGHT INTO SATURDAY.
HOWEVER...JUST 24 HOURS AGO WE WERE LOOKING AT A DRY FORECAST FOR
THAT TIME FRAME SO CONFIDENCE ON ANY TIMING HAS TO BE QUITE LOW.
ANOTHER DISTURBANCE IS LIKELY LATE IN THE WEEKEND OR EARLY NEXT
WEEK. THE MAIN POINT OF THIS FORECAST WILL BE TO HAVE AN EXTENDED
PERIOD OF COOLER AND UNSETTLED WEATHER. THERE WILL BE A THREAT OF
ACCUMULATING SNOWFALL WITH ANY OF THE DISTURBANCES THAT MOVE
THROUGH.
&&
.AVIATION...WINDS HAVE BEEN MORE WESTERLY AT KDEN AND KBJC WITH
NORTHWESTERLY AT KAPA. LATEST RAP AND HRRR CONTINUE TO INDICATE
NORTHWEST WINDS ACROSS THE AREA AIRPORTS THROUGH 01Z...STILL
EXPECTING WINDS TO BECOME A BIT MORE NORTHWEST AS MIXING
CONTINUES WITH SOME GUSTS AROUND 35 KTS. WINDS TO WEAKEN AFTER 01Z
AND BECOMING SOUTHERLY BY 03Z AS DRAINAGE PATTERN DEVELOPS. WINDS
TO BE MORE WESTERLY AT BJC DUE TO THE LOCAL DOWNSLOPE WITH
OCCASIONAL GUSTS TO 30 KTS POSSIBLE. ON TUESDAY...WINDS TO SHIFT
TO THE NORTHWEST BY 15Z WITH SPEEDS LESS THAN 10 KTS. WINDS COULD
BECOME NORTHEAST OR EAST AT DEN DURING THE AFTERNOON AS MODELS
SHOW WEAK SURFACE HIGH DEVELOPING IN THE DENVER AREA. VFR TO
CONTINUE.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....BARJENBRUCH
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1023 AM MDT MON MAR 18 2013
.UPDATE...
&&
.SHORT TERM...WEB CAMS AND RADAR ACROSS MOUNTAINS SHOWING SNOW
ALONG CONTINENTAL DIVIDE OF SUMMIT AND GRAND COUNTIES WITH MOST OF
THE SNOW ON WEST AND NORTHWEST FACING SLOPES. WEB CAMS SUGGESTING
SOME SNOW ALONG THE GORE AND PARK RANGES OF WESTERN JACKSON
COUNTY. MOST MOUNTAIN AREAS TO CONTINUE TO SEE OROGRAPHIC SNOW
INTO THE EVENING...WILL NEED TO BOOST POPS AND ACCUMULATION IN
THE FAVORED AREAS. NO ADVISORIES AT THIS TIME. GUSTY WINDS
CURRENTLY SPREADING ACROSS FOOTHILLS AND ADJACENT PLAINS AS MIXING
CONTINUES. OVERALL...CURRENT WIND GRIDS SEEM ON REASONABLE...MAY
NEED TO ADJUST TIMING AND INCREASE SPEEDS A FEW LOCATIONS. FIRE
DANGER TO BE ELEVATED THIS AFTERNOON DUE TO THE GUSTY WINDS AND
LOW HUMIDITY. STILL THINKING HUMIDITY SHOULD REMAIN ABOVE CRITICAL
THRESHOLDS...THOUGH MAY GET CLOSE ACROSS THE PALMER DIVIDE AND FAR
EASTERN PLAINS. WILL HOLD OFF ON HOISTING ANY RED FLAG WARNINGS.
LATEST RAP SHOWING THE DEVELOPMENT OF SOME PRECIP FAR NORTHEAST
PLAINS THIS EVENING. THIS AREA DOES APPEAR TO BE IN THE FAVORED
UPWARD MOTION PORTION OF THE APPROACHING JET. FOR NOW WILL HOLD
OFF ON INCLUDING IN THE GRIDS...WILL CONTINUE TO MONITOR.
POTENTIAL FOR MOUNTAIN WAVE TONIGHT AS STABLE LAYER DEVELOPS NEAR
MOUNTAIN TOP. WINDS TO INCREASE ACROSS MOUNTAINS AND FOOTHILLS
OVERNIGHT...SHOULD REMAIN BELOW HIGH WIND CRITERIA. COULD ALSO BE
A BIT GUSTY NEAR THE BASE OF THE FOOTHILLS AS WELL.
.AVIATION...WESTERLY WINDS SPREADING ACROSS AREA AIRPORTS AT THIS
TIME...THOUGH A BIT OF AN EDDY CURRENTLY AT APA WITH LIGHT
SOUTHEAST WINDS THERE. SHOULD SEE WINDS SHIFT TO THE NORTHWEST BY
18Z AS MIXING CONTINUES. CURRENT TAF TRENDS STILL SEEM ON TRACK
AND WILL CONTINUE FOR THE UPCOMING ISSUANCE.
&&
.PREV DISCUSSION... /ISSUED 337 AM MDT MON MAR 18 2013/
SHORT TERM...STRONG NORTHWEST FLOW ALOFT WILL PREVAIL TODAY WITH A
120 KNOT JET PASSING OVER THE STATE. SATELLITE SHOWING SOME MOISTURE
EMBEDDED IN THE NORTHWEST FLOW ALOFT OVER NORTHERN UTAH AND SOUTHERN
IDAHO. THIS WILL MOVE OVER THE MOUNTAINS OF NORTH CENTRAL COLORADO
TODAY. THIS MOISTURE COMBINED WITH THE NORTHWEST FLOW WILL PRODUCE
AREAS OF OROGRAPHIC SNOW. FAVORED WEST TO NORTHWEST FACING SLOPE MAY
SEE UP TO 3 INCHES TODAY. PROTECTED AREA WILL SEE LITTLE OR NO SNOW.
WINDS WILL INCREASE THIS MORNING ONCE THE AIRMASS WARMS UP AND MIXES
SOME OF THE WINDS ALOFT DOWN. THE WIND SPEEDS WILL LIKELY BE A
LITTLE LESS THAN YESTERDAY. THE WINDS COMBINED WITH LOW RELATIVE
HUMIDITY WILL INCREASE THE FIRE DANGER AGAIN TODAY. EXPECT RELATIVE
HUMIDITIES TO STAY ABOVE 15 PERCENT FOR MOST OF THE DAY...SO WILL
NOT ISSUE A RED FLAG WARNING.
COOLER AIR HAS PUSHED INTO THE STATE OVERNIGHT. THIS WILL RESULT IN
COOLER TEMPERATURES TODAY. HIGHS WILL RANGE FROM THE UPPER 40S TO
LOWER 50S ACROSS NORTHEAST COLORADO.
FOR TONIGHT...DRIER AIR WILL MOVE OVER THE MOUNTAINS AND BRING THE
SNOW TO AN END. WINDS IN AND NEAR THE FOOTHILLS WILL INCREASE
OVERNIGHT AS A MOUNTAIN WAVE DEVELOPS. MODELS SHOWING A STABLE LAYER
NEAR MOUNTAIN TOP...WHICH AIDS IN THE DEVELOPMENT OF A MOUNTAIN
WAVE. THE WINDY LOCATIONS IN AND NEAR THE FOOTHILLS WILL SEE GUSTS
TO 60 MPH OVERNIGHT. OVER THE PLAINS...WINDS WILL BECOME LIGHT
AROUND SUNSET AS THE AIRMASS STABILIZES.
LONG TERM...DRY NW FLOW ALOFT WILL BE OVER THE AREA ON TUE. WINDS
SHOULD DECREASE BUT WILL REMAIN GUSTY AT TIMES IN THE MTNS...NRN
FOOTHILLS AND OVER THE PLAINS NR THE WY-NE BORDER. HIGHS ON TUE
SHOULD BE NR SEASONAL NORMALS. FOR WED THE FLOW ALOFT WILL BECOME
MORE ZONAL WITH THE MTNS SEEING SOME INCREASE IN MOISTURE BY AFTN
SO WILL KEEP A CHC OF -SHSN IN THE FCST. WINDS WILL INCREASE IN
THE MTNS AND FOOTHILLS HOWEVER AT THIS TIME SPEEDS LOOK TO BE BLO
HIGHLIGHT CRITERIA. OVER NERN CO IT WILL BE DRY WITH AFTN HIGHS
IN THE 55 TO 60 DEGREE RANGE.
ON THU A FAST MOVING UPPER LEVEL TROUGH WILL APPROACH FM THE NW
AND AFFECT THE AREA MAINLY FROM THU AFTN INTO THU NIGHT. SHOULD
SEE A BETTER CHC OF SNOW IN THE MTNS DUE TO BETTER LAPSE RATES
ALONG WITH SOME MID LVL QG ASCENT. OVER NERN CO SFC LOW PRES WILL
EXTEND FM SERN WY INTO SERN CO THRU THE AFTN WITH THE MODELS STILL
SHOWING AN INVERTED SFC TROUGH ALONG THE FRONT RANGE. NORMALLY
THIS TYPE OF SET UP WOULD KEEP THE BEST CHC OF PCPN OVER THE
PLAINS WITH LESS ACTIVITY IN AND NR THE FOOTHILLS. HOWEVER WITH
DECENT LAPSE RATES AND MID LVL QG ASCENT COULD STILL SEE SOME
SHOWER ACTIVITY WEST OF THE INVERTED SFC TROUGH SO WILL KEEP IN
CHC POPS IN ALL AREAS. PCPN TYPE WILL BE TRICKY HOWEVER IT DOES
APPEAR BY THU EVENING TEMPS WILL BECOME COLD ENOUGH FOR SNOW OVER
NERN CO BEFORE PCPN GRADUALLY ENDS AFTER MIDNIGHT.
FOR FRI AND SAT THE LATEST GFS HAS A RADICALLY DIFFERENT SOLUTION
AS COMPARED TO THE LAST TWO NIGHTS. IT NOW SHOWS A STG UPPER LEVEL
TROUGH DEVELOPING OVER THE AREA WITH AN UPPER LEVEL LOW OVER SRN
COLORADO BY 12Z SAT WITH RATHER STG UPSLOPE FLOW FROM FRI NIGHT
THRU MIDDAY SAT WITH THE POTENTIAL FOR SOME DECENT SNOWFALL
ESPECIALLY ALONG THE FRONT RANGE URBAN CORRIDOR INTO THE
FOOTHILLS. MEANWHILE THE ECMWF SHOWS A SIMILAR SOLUTION ALTHOUGH
IT HAS MORE OF AN OPEN TROUGH AND DOES NOT CLOSE OFF AN UPPER
LEVEL LOW LIKE THE GFS SHOWS. AT THIS POINT IT APPEARS MOST OF FRI
WILL BE DRY WITH PCPN HOLDING OFF UNTIL FRI EVENING IF THE
CURRENT SOLUTIONS ARE CORRECT. FOR NOW WILL INCLUDE SOME LOW POPS
FOR FRI NIGHT INTO SAT ACROSS NERN CO AND HAVE CHC POPS IN THE
MTNS UNTIL THERE IS SOME CONTINUITY BETWEEN MODEL RUNS. AS FOR
TEMPS WILL KEEP HIGHS IN THE UPPER 30S TO LOWER 40S BOTH FRI AND
SAT ACROSS NERN CO.
BY SUN BOTH THE ECMWF AND GFS AGREE FOR NOW THAT THE UPPER LEVEL
TROUGH WILL MOVE SE OF THE AREA WITH DRIER AIR SPREADING ACROSS IN
NWLY FLOW ALOFT. THUS WILL ONLY MENTION SOME LOW POPS IN THE MTNS
AND KEEP IT DRY ELSEWHERE. WILL KEEP HIGHS IN THE 40S FOR SUN
ACROSS NERN CO.
AVIATION...NORTHWEST WINDS WILL PREVAIL THROUGH THE DAY WITH GUSTS
TO 35 KNOTS POSSIBLE AT THE DENVER AIRPORTS. WINDS WILL BRIEFLY TURN
WEST OR SOUTHWESTERLY AT TIMES THIS MORNING. THE GUSTY WINDS WILL
DECREASE AFTER 00Z AND BECOME DRAINAGE AROUND 03Z. EXPECT SCATTERED
CUMULUS CLOUDS TO FORM THIS AFTERNOON AT AROUND 9000
FEET...OTHERWISE MOSTLY CLEAR SKIES WILL PREVAIL.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....RPK
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS MIAMI FL
110 PM EDT MON MAR 18 2013
.UPDATE...
QUICK UPDATE TO BUMP UP POPS FOR THE GULF COAST THIS AFTERNOON. AN
MCS IS HOLDING TOGETHER ACROSS THE EASTERN GULF AND WILL MAKE ITS
WAY TOWARDS THE GULF COAST LATER THIS AFTERNOON. SPC ADDED THE
GULF COAST IN A 5 PERCENT PROBABILITY FOR DAMAGING WINDS AS THE
STORMS COME IN TOWARDS PEAK HEATING. UPDATED THE HWO TO ACCOUNT
FOR THE POSSIBILITY OF A COUPLE STRONG STORMS. HOWEVER...THE HRRR
SHOWS THE CONVECTION WEAKENING AS IT GETS AWAY FROM THE LOOP
CURRENT...WITH MAINLY STRATIFORM RAIN AND EMBEDDED THUNDERSTORMS.
THE HRRR SCENARIO IS WHAT TYPICALLY HAPPENS...ESPECIALLY SINCE
THE SHELF WATERS ARE STILL COOL OFF THE COAST.
&&
.PREV DISCUSSION... /ISSUED 934 AM EDT MON MAR 18 2013/
UPDATE...
ISOLATED SHOWERS WERE STREAMING FROM WEST TO EAST ACROSS THE
REGION THIS MORNING AHEAD OF A SHORTWAVE. THERE HAVE EVEN BEEN A
FEW LIGHTNING STRIKES JUST NORTH OF LAKE OKEECHOBEE. THE 12Z
SOUNDING SHOWED AN INVERSION JUST ABOVE 800MB...AND THIS SHOULD
PREVENT THUNDERSTORMS ACROSS THE SOUTHEASTERN THIRD OF THE REGION.
THE 12Z TBW SOUNDING WAS MORE UNSTABLE...AND THE LAPSE RATES IN
THE MID LEVELS WERE PRETTY STEEP. 500MB TEMPS WERE -13C ON THE MFL
SOUNDING AND -14C ON THE TBW SOUNDING. THE UPPER LEVEL JET WILL BE
LOCATED OVER CENTRAL FLORIDA...WITH UPPER LEVEL DIVERGENCE NEAR
THE LAKE. SO ADDED THUNDERSTORM WORDING TO THE LAKE REGION AND
THE GULF COAST FOR TODAY. THERE IS ALSO A LARGE AREA OF
THUNDERSTORMS OVER THE EASTERN GULF ASSOCIATED WITH A SHORTWAVE.
HIGH RES MODELS INDICATE THAT THESE STORMS WILL FOLLOW THE LOOP
CURRENT TO THE SOUTHEAST...BUT A FEW COULD MAKE IT INTO THE
OFFSHORE GULF WATERS.
THE UPPER LEVEL JET WILL SLOWLY SLIDE SOUTH TONIGHT...WITH SOUTH
FLORIDA IN THE RIGHT ENTRANCE REGION. GLOBAL MODELS AND HIGH RES
MODELS INDICATE AN AREA OF CONVECTION MOVING FROM THE NORTH AND
NORTHWEST TONIGHT...AND ACROSS SOUTH FLORIDA OVERNIGHT. BUMPED UP
POPS SIGNIFICANTLY TO ACCOUNT FOR THIS...TO 40 PERCENT ACROSS THE
REGION. ALSO INCLUDED SLIGHT CHANCE OF THUNDERSTORMS AS WELL.
PREV DISCUSSION... /ISSUED 720 AM EDT MON MAR 18 2013/
AVIATION...
VFR WILL GENERALLY BE THE RULE TODAY, WITH SOME MVFR POSSIBLE AS
ISOLATED SHOWERS MOVE ACROSS PORTIONS OF SOUTH FLORIDA TODAY. THERE
IS A WEAK BOUNDARY STALLED OVER CENTRAL FLORIDA. THESE SHOWERS
WILL MOVE TO THE NORTHEAST, THUS KEPT VCSH IN THE TAF FOR KPBI.
THEY SHOULD REMAIN ISOLATED AND QUICK MOVING THROUGH THE DAY.
GIVEN THIS, HAVE NOT ADDED ANY TEMPO GROUPS OR PREVAILING
CONDITIONS HIGHER THAN THE VCSH. ALSO, WHILE NONE IS EXPECTED OR
FORECAST AT THIS TIME, THERE COULD BE ISOLATED LIGHTENING STRIKES
IN THE NORTHERN PORTIONS OF SOUTH FLORIDA.
GIVEN THE ADDED MOISTURE FROM TODAY, FOG MAY BE POSSIBLE IN THE
INTERIOR PORTION OF SOUTH FLORIDA. IF IT DOES FORM, WHICH WILL
DEPEND ON SKIES CLEARING ENOUGH TO ALLOW SOME COOLING, IT COULD
ENCROACH ON TAF SITES SUCH AS KAPF AND KTMB. BUT, CONFIDENCE IS
VERY LOW AT THIS POINT, SO AGAIN, HAVE NOT MENTIONED THEM IN THE
TAFS FOR TONIGHT AS YET. 13/SI
PREV DISCUSSION... /ISSUED 444 AM EDT MON MAR 18 2013/
DISCUSSION...
SCATTERED SHOWERS CONTINUE TO PASS ACROSS THE CENTRAL FLORIDA
PENINSULA THIS MORNING. THESE SHOWERS ARE PRIMARILY DRIVEN BY A WEAK
MID LEVEL SHORTWAVE TRAVERSING THROUGH CENTRAL FLORIDA. A FEW OF
THESE SHOWERS COULD AFFECT THE SOUTH FLORIDA AREA THROUGH THE DAY
ESPECIALLY ACROSS THE SOUTHWEST FLORIDA COAST AS THIS SHORTWAVE
INTERACTS WITH A SLIGHTLY DEEPER MOISTURE FIELD. THIS DEEPER
MOISTURE AXIS WILL LINGER ACROSS THE AREA INTO TUESDAY KEEPING
SLIGHT CHANCES FOR SHOWERS AREA WIDE.
BY LATE TUESDAY INTO EARLY WEDNESDAY A COLD FRONT WILL BEGIN TO
SLOWLY PUSH INTO THE AREA KEEPING CHANCES FOR SHOWERS THROUGH
WEDNESDAY. CURRENTLY BELIEVE THERE COULD BE A FEW THUNDERSTORMS
TUESDAY AFTERNOON WITH THE FRONT IN THE AREA AND POSSIBLE SEA BREEZE
INTERACTIONS. THIS FRONT SHOULD STALL ACROSS THE EXTREME SOUTHERN
PART OF THE AREA AND SHOULD ACT AS A FOCUS FOR THUNDERSTORM
POTENTIAL AGAIN WEDNESDAY AFTERNOON. IN ADDITION TO THIS THE
THERMODYNAMIC PARAMETERS FOR TUESDAY AND WEDNESDAY LOOK DECENT FOR
THUNDERSTORM DEVELOPMENT AS WELL WITH SBCAPE VALUES EACH AFTERNOON
AROUND 1000-1500 J/KG AND LIFTED INDICES IN THE -5 TO -6C RANGE. BY
THURSDAY HIGH PRESSURE TO THE NORTH BEGINS TO BRIEFLY BUILD INTO THE
FLORIDA PENINSULA PUSHING WHATS LEFT OF THE FRONT FURTHER SOUTH.
THE FRONT IS THEN EXPECTED TO BEGIN A PUSH BACK TO THE NORTH AS A
WARM FRONT AS AN AREA OF LOW PRESSURE ACROSS TEXAS BEGINS TO DEEPEN.
THIS WILL BRING A RETURN OF SHOWER AND POSSIBLY THUNDERSTORM CHANCES
ACROSS THE AREA FRIDAY AFTERNOON ALTHOUGH BETTER THUNDERSTORM
CHANCES SHOULD BE ACROSS THE GULF COASTAL AREAS DUE TO BETTER
PROXIMITY OF THE FRONT. THIS SAME AREA OF LOW PRESSURE WILL SURGE TO
THE NORTHEAST AND ACROSS THE LOWER MISSISSIPPI VALLEY OVER THE
WEEKEND AND SWING ANOTHER COLD FRONT ACROSS SOUTH FLORIDA BY SUNDAY.
A FEW SHOWERS ASSOCIATED WITH THE FRONT MAY LINGER INTO EARLY
NEXT WEEK BUT AFTER THAT...A MORE PROLONGED DRYING TREND LOOKS TO BE
IN STORE FOR SOUTH FLORIDA HEADING INTO THE LAST PART OF THE MONTH.
MARINE...
SOUTHEAST WINDS AT 10-15 KNOTS ACROSS THE AREA WATERS WILL SLOWLY
VEER MORE TO THE SOUTH AND THEN SOUTHWEST BY TUESDAY AHEAD OF AN
APPROACHING COLD FRONT. SEAS WILL BE IN THE 1-3 FOOT RANGE ACROSS
THE ATLANTIC THROUGH MIDWEEK BEFORE INCREASING SLIGHTLY IN THE
WAKE OF THE COLD FRONT.
FIRE WEATHER...
DEEPER MOISTURE WILL BEGIN TO WORK ITS WAY INTO THE SOUTH FLORIDA
PENINSULA AHEAD OF AN APPROACHING FRONTAL BOUNDARY. THIS WILL KEEP
RELATIVE HUMIDITY VALUES WELL ABOVE CRITICAL THRESHOLDS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 69 85 69 81 / 40 20 40 40
FORT LAUDERDALE 71 84 69 82 / 40 20 40 40
MIAMI 70 85 70 83 / 40 20 40 40
NAPLES 65 84 66 80 / 40 20 30 40
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...84/AK
AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
147 PM EDT MON MAR 18 2013
.PREV DISCUSSION... /ISSUED 1040 AM EDT MON MAR 18 2013/
UPDATE...
14Z SURFACE ANALYSIS SHOWERS A COLD AIR WEDGE ACROSS THE NORTHEAST
CWFA THIS MORNING. WINDS CONTINUE TO SWITCH AROUND TO THE N/NE UNDER
THE WEDGE...REINFORCING THE COOLER AIR. NOT CONFIDENT ON HOW FAR THE
WEDGE WILL BUILD WESTWARD...WILL HAVE TO CONTINUE TO MONITOR THE
OBS. SINCE THE AIRMASS IS MORE STABLE ACROSS THAT PART OF THE
STATE...HAVE CHANCED THE PTYPE TO STRATIFORM AND ADDED PATCHY
DRIZZLE FOR A FEW MORE HOURS THIS MORNING. HOWEVER...AS THE HEAVIER
PRECIP GETS NEARER...IT STILL WON`T BE SURFACE BASED...BUT SHOULD
BECOME MORE CONVECTIVE WITH A SLIGHT CHANCE OF THUNDER.
FURTHER SOUTH...DO THINK MORE SURFACE INSTABILITY WILL BE PRESENT.
ALREADY ON THE VISIBLE SATELLITE IMAGERY CAN SEE A FEW BREAKS IN THE
THIN STRATUS DECK. THOSE AREAS ABLE TO BREAK OUT WILL SEE THE
HIGHEST INSTABILITY. IN ADDITION...60 DEGREE DEWPOINTS ARE BEGINNING
TO CREEP IN ACROSS SOUTHERN AREAS. LARGE SCALE FORCING WILL REMAIN
WELL TO THE NORTH...BUT SRH MAY BE ENHANCED JUST ALONG THE WEDGE
FRONT. LARGE HAIL AND DAMAGING WIND GUSTS WILL BE THE PRIMARY MODES
OF SEVERE WEATHER THIS AFTERNOON...BUT ISOLD TORNADOES ARE POSSIBLE
WHERE THE LOW LEVEL SHEAR IS ENHANCED. EVEN IF AREAS IN THE SOUTH
ARE ABLE TO COMPLETELY CLEAR OUT...DO THINK CLOUDS WILL FILL BACK IN
AS WIDESPREAD AREA OF PRECIP APPROACHES FROM THE NW. THIS SHOULD
HELP LIMIT THE COVERAGE OF SEVERE STORMS. POTENTIAL FOR SEVERE
WEATHER SHOULD BE BETWEEN 2PM AND 10PM AHEAD OF THE ACTUAL FRONT.
HIGH RESOLUTION MODELS SHOW TWO DISTINCT WAVES OF PRECIP. THE FIRST
WAVE IS IN THE AFTERNOON...AND THE SECOND WAVE IS OVERNIGHT WITH THE
FROPA. AGAIN...SINCE WIDESPREAD FORCING REMAINS WELL TO THE
NORTH...THINK CONVECTION WILL BEGIN TO WEAKEN WITH THE LOSS OF
HEATING. THUNDERSTORMS WILL CONTINUE POSSIBLE OVERNIGHT...BUT SEVERE
WEATHER CHANCES SHOULD LESSEN WITH THE LOSS OF SURFACE INSTABILITY.
NLISTEMAA
PREV DISCUSSION... /ISSUED 735 AM EDT MON MAR 18 2013/
PREV DISCUSSION... /ISSUED 421 AM EDT MON MAR 18 2013/
STRONG TO SEVERE STORMS EXPECTED TODAY AND TONIGHT...
SHORT TERM /TODAY THROUGH TUESDAY/...
PRIMARY CONCERN THROUGH THE SHORT TERM IS CONVECTION EXPECTED TODAY
THROUGH EARLY TUESDAY ACCOMPANYING FRONTAL PASSAGE. MODELS IN FAIRLY
GOOD AGREEMENT WITH INCREASING PRECIP COVERAGE ACROSS THE AREA
THROUGH THIS AFTERNOON...AHEAD OF THE BOUNDARY...THEN PUSHING THE
FRONT THROUGH THE AREA BY TUESDAY MORNING.
HI RES SHORT TERM MODELS SHOWING TWO WAVES OF PRECIP THROUGH TUESDAY
MORNING...AND PRECIP TODAY WILL BE MORE CONVECTIVE IN NATURE THAN
HAD BEEN EXPECTED OVER THE LAST SEVERAL DAYS. HRRR AND LOCAL WRF
BRING PRECIP INTO THE AREA BY LATE MORNING...AND SPREAD IT EASTWARD
THROUGH THE AFTERNOON. THIS ACTIVITY AND ASSOCIATED CLOUD COVER WILL
IMPACT THE DESTABILIZATION OF THE ATMOSPHERE...BUT EVEN SO...MODELS
STILL SUGGEST ML CAPE OF 700 TO 900 J/KG THROUGH THE AFTERNOON
ACROSS NORTH AND CENTRAL GEORGIA...AND 900-1100 J/KG INTO THE
OVERNIGHT HOURS ACROSS PORTIONS OF CENTRAL AND SOUTH GEORGIA. HAVE
CONTINUED WITH ISOLATED THUNDER MENTION THROUGH THE MORNING
HOURS...AND THEN PREDOMINATE THUNDERSTORMS THROUGH THE EVENING.
MODELS CONTINUE TO ADVERTISE WEDGE IN PLACE THROUGH THE DAY...WHICH
WILL SUPPORT A MORE STABILIZED ENVIRONMENT ACROSS NORTHEAST GEORGIA.
THAT BEING SAID...THE PERIPHERY OF THE WEDGE WILL SUPPORT LOCALIZED
ENHANCED SRH AND THE DEVELOPMENT OF STRONG TO SEVERE STORMS. THIS
INCREASED LOW-LEVEL SHEAR COULD SUPPORT ISOLATED TORNADOES. PRIMARY
CONCERNS ACROSS THE AREA WILL BE DAMAGING WINDS AND LARGE
HAIL...ESPECIALLY IN ORGANIZED BANDS OF CONVECTION. ROTATION IS
POSSIBLE WITHIN STRONGER UPDRAFTS IN ORGANIZED STORMS.
SEVERE POTENTIAL DOES DIMINISH SOMEWHAT IN THE OVERNIGHT HOURS...AND
SOME MODELS ARE SUGGESTING A LESS ORGANIZED BAND OF ACTIVITY
ACCOMPANYING THE FRONT THROUGH THE AREA OVERNIGHT INTO TUESDAY
MORNING. WITH SOME UNCERTAINTY ON TIMING AND STRENGTH OF THE
ACTIVITY...HAVE GENERALLY GONE WITH SLIGHTLY LESS THAN CATEGORICAL
POPS AND SCATTERED THUNDERSTORMS FOCUSED ALONG THE BOUNDARY
OVERNIGHT. PRECIP CHANCES SHOULD DROP OFF QUICKLY BEHIND THE
FRONT...SO HAVE LIMITED POPS AND TS MENTION FOLLOWING THE FROPA.
FRONT IS EXPECTED TO PUSH THROUGH THE CWA BY TUESDAY
AFTERNOON...WITH A DRIER AND COOLER AIR MASS IN PLACE AS A RESULT.
THIS AIR MASS WILL REMAIN IN PLACE INTO THE EXTENDED FORECAST
PERIODS.
31
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
EXTENDED PERIOD BEGINS WITH THE DEVELOPMENT OF A LONGWAVE EAST
COAST TROUGH WHICH WILL ALLOW FOR TEMPS DROPPING SOME 10 DEGREES
BELOW NORMAL INITIALLY WITH ADDITIONAL SHOTS OF COOL TO COLD AIR
THROUGH WEEKS END. WILL SEE STRONG IMPULSE PUSH THROUGH THE
TENNESSEE VALLEY EARLY WEDNESDAY WITH MAIN FORCING REMAINING JUST
NORTH OF THE GEORGIA MOUNTAINS. MID LEVEL MOISTURE AND LIFT
SUPPORT SLIGHT CHANCE POPS BUT WITH DEWPOINTS REMAINING IN THE
20S...WILL KEEP POPS IN THE SILENT 10 RANGE FOR NOW. THIS WILL
BEAR WATCHING CLOSELY HOWEVER AS IF PRECIP COULD BE
REALIZED...COLD TEMPS ALOFT AND WET BULB EFFECTS LOOK TO EASILY
SUPPORT WINTRY PRECIP FOR THE NORTHERN TIER.
NEST SYSTEM WILL TAKE SHAPE FRIDAY OVER THE SOUTHERN PLAINS AS
SOUTHERN STREAM OF THE JET GETS ACTIVE AND DEVELOPS LOW PRESSURE
OVER EAST TEXAS. FAVORABLE LARGE SCALE ISENTROPIC ASCENT PROFILE
FOR THE GULF COAST INCLUDING THE LOCAL AREA THROUGH FRIDAY. WILL
HAVE TO MONITOR ONSET CLOSELY FOR THIS SYSTEM AS COLD AIR REMAINS
TRAPPED IN THE MOUNTAINS INITIALLY WHICH COULD LEAD TO ADDITIONAL
WINTRY WX CONCERNS. WARM BELT SHOULD CONTINUE TO LIFT NORTH AS
PRECIP BECOMES MORE ENTRENCHED OVER THE AREA WITH ALL RAIN
EXPECTED FOR THE REMAINDER OF THE TENURE OF THIS STORM SYSTEM.
SIGNIFICANT DIFFERENCES AMONG THE ECMWF AND GFS BY THIS TIME
PERIOD WITH EURO CLEARING IT OUT A BIT FASTER BUT BRINGING IN NEXT
SYSTEM MUCH FURTHER SOUTH THAN GFS. MOST CONFIDENCE IS FOR LATE
FRI AND EARLY SAT AND INCREASED POPS TO HIGH END CHANCE THIS FAR
OUT BUT FORECAST WILL LIKELY REQUIRE SIGNIFICANT TWEAKS WITH
SUBSEQUENT ISSUANCES.
DEESE
&&
.AVIATION...
18Z UPDATE...
COLD FRONT CURRENTLY ACROSS NORTHERN AL AND CENTRAL MS. SHOWERS
AND THUNDERSTORMS WILL CONTINUE TO DEVELOP AHEAD OF THE BOUNDARY
AND IMPACT THE TERMINAL SITES THIS AFT/EVE. STORMS SHOULD IMPACT
THE NORTHERN TERMINAL SITES BETWEEN 20Z AND 00Z. FOR THE SOUTHERN
SITES...BETWEEN 21Z AND 01Z. THERE WILL BE A BRIEF BREAK IN THE
PRECIS DURING THE EVENING...BUT WIDESPREAD SHOWERS AND ISOLD TSRA
ARE POSSIBLE ALONG WITH THE FROPA OVERNIGHT.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM CONFIDENCE ALL ELEMENTS.
NLISTEMAA
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 62 48 67 36 / 90 90 40 5
ATLANTA 68 47 64 39 / 90 90 30 5
BLAIRSVILLE 58 42 57 31 / 90 70 20 5
CARTERSVILLE 68 45 63 33 / 80 80 20 5
COLUMBUS 74 54 68 41 / 90 60 40 5
GAINESVILLE 60 45 63 37 / 90 90 30 5
MACON 72 54 70 38 / 80 80 50 5
ROME 70 44 64 33 / 70 70 20 10
PEACHTREE CITY 70 49 65 32 / 90 80 30 5
VIDALIA 77 60 74 45 / 60 90 40 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
505 PM CDT MON MAR 18 2013
.DISCUSSION...
345 PM CDT
WHILE THE TRUE VERNAL EQUINOX ARRIVES WEDNESDAY...AND WE ARE THREE
WEEKS INTO METEOROLOGICAL WINTER...THE MAIN WEATHER HEADLINE THIS
WEEK WILL BE HOW UNSPRING-LIKE THE TEMPERATURES WILL BE. THIS
PRESENTS THE MAIN FORECAST CHALLENGE...ALONG WITH ANY SMALL
CHANCES FOR SNOW SHOWERS.
SYNOPSIS AND LATE THIS AFTERNOON...THE POTENT UPPER LEVEL LOW IS
MOVING EAST ACROSS MN THIS AFTERNOON...WITH THE MID-LEVEL JET AND
A VORT LOBE OF THE SYSTEM RUSHING EASTWARD OVER NORTHERN IL.
ENHANCEMENT ON THE LEADING EDGE OF THESE STEEPER MID-LEVEL LAPSE
RATES AND CONVERGENCE IS SEEN IN SNOW SHOWERS TRAVERSING NORTHEAST
ILLINOIS AS OF 3 PM. SPOTTIER HEAVIER SNOWFALL RATES WILL BE SEEN
IN THIS ACTIVITY AS IT DEPARTS. THE SURFACE ARCTIC FRONT OF THIS
SYSTEM IS CROSSING THE MISSISSIPPI RIVER AND WILL MOVE THROUGH THE
ENTIRE CWA BETWEEN 5 AND 9 PM. THIS WILL TURN THE SYNOPTIC PATTERN
TO ONE OF NORTHWEST FLOW AND COLD WHICH WILL CONTINUE TO REINFORCE
ITSELF THROUGH THE WEEK AS THE UPPER AND SURFACE LOWS EXPAND AND
SLOW ACROSS THE CENTRAL AND EASTERN GREAT LAKES. NUMEROUS SHORT
WAVE IMPULSES ARE EXPECTED TO RIDE AROUND THIS FEATURE WITH
MINIMAL CAUSES FOR SNOW...BUT EACH DRIVING COLD SURGES BACK INTO
THE AREA.
TONIGHT...SHORT TERM GUIDANCE IS IN GOOD AGREEMENT ON THE TIMING
OF THE ARCTIC FRONT THIS EVENING...ALONG WITH AGREEING THAT THE
STEEPENING OF THE LOW-LEVEL LAPSE RATES WILL LIKELY PRODUCE
SURFACE-BASED INSTABILITY. FORECAST SOUNDINGS FROM THE RAP YIELD
AROUND 50 J/KG OF MLCAPE ALONG AND IMMEDIATELY BEHIND THE FRONT.
THE SATURATED DEPTH AT THE TOP OF THIS MIXED LAYER IS QUITE
SHALLOW BUT MOST CONVECTIVE-ALLOWING ARW AND WRF GUIDANCE DO
CONTINUE TO PRODUCE A SPATTERING OF HIGHER REFLECTIVITY INDICATIVE
OF SNOW SHOWERS. WILL CARRY FLURRIES WITH A MENTION OF ISOLATED TO
SCATTERED SNOW SHOWERS.
THE FRONT WILL BRING BOTH STRONG HEIGHT AND PRESSURE RISES WHICH
ARE LINED UP WELL WITH A UNIDIRECTIONAL WIND COLUMN IN THE LOW-
LEVELS. THE TOP OF THE MIXED LAYER ON THE LATEST RAP GUIDANCE AS
WELL AS LOCAL ARW DOES YIELD 40 MPH GUSTS THIS EVENING. HAVE
INCLUDED SUCH GUSTS IMMEDIATELY BEHIND THE FRONT AND WOULD NOT BE
SURPRISED IF SOME PLACES IN THE SOUTHWEST FORECAST AREA COME IN A
BIT HIGHER. IF SNOW SHOWERS DO DEVELOP...SOME NOTABLE REDUCTIONS
IN VISIBILITY MAY BE SEEN DUE TO THE COMBINATION OF WINDS AND
SNOWFALL. WITH TEMPERATURES FALLING QUICKLY...WIND CHILLS IN THE
NORTHWEST FORECAST AREA LOOK TO ALREADY BE IN THE SINGLE DIGITS
BY 9 PM THIS EVENING. THIS DEGREE OF COLD AIR WILL SWEEP OVER THE
ENTIRE FORECAST AREA WITH EARLY MORNING TEMPERATURES IN THE MID
TEENS TOWARD ROCKFORD TO AROUND 20 EAST. THESE ARE ABOUT 10 TO 15
DEGREES BELOW NORMAL.
TUESDAY AND TUESDAY NIGHT...UPPER LEVEL HEIGHTS WILL NOT RISE ANY
ON TUE WITH CYCLONIC FLOW IN COMPLETE CONTROL. HOWEVER...MOST
SHORT WAVE ENERGY IS LIKELY TO REMAIN TO THE NORTH AND EAST...SO
IT IS POSSIBLE TO SEE A LITTLE SCATTERING IN SOUTHERN AREAS. WITH
THE FIRST COLD POCKET OF AIR SHIFTING SLIGHTLY EAST OF THE
AREA...TEMPERATURES SHOULD MAKE IT BACK CLOSE TO TODAYS HIGHS.
WIND CHILLS WILL REMAIN IN THE MID TEENS TO MID 20S HOWEVER. A
SECOND COLD FRONT PUSHES THROUGH TOMORROW NIGHT ASSOCIATED WITH A
SHORT WAVE ROTATING AROUND THE PARENT LOW. THIS APPEARS STARVED
FOR DEEP MOISTURE BUT THE COLD AIR WILL BRING LOW TEMPERATURES
EVEN COOLER TUE NIGHT AND WIND CHILLS BELOW ZERO FOR WED MORNING.
WEDNESDAY AND THURSDAY...DUE TO SUCCESSIVE COLD FRONTS AND LIKELY
BROKEN TO OVERCAST STRATOCU GIVEN FORECAST SOUNDINGS FOR
WED...THIS SHOULD BE THE DAY WITH THE COLDEST HIGH TEMPERATURE. IN
FACT...THE HIGH TEMPERATURE FORECAST /22/ REMAINS A TIED RECORD
LOW MAXIMUM FOR ROCKFORD ON MARCH 20TH. BACKWARD PARCEL
TRAJECTORIES FROM THE GFS IN THIS TIME INDICATE THE AIR MASS
SOURCE REGION TO BE THE NORTHERN PROVINCES OF CANADA...NOT A
TYPICAL SOURCE REGION FOR LATE MARCH FOR THIS AREA. DEPENDING ON
CLOUD COVER WED NIGHT AND THE AMOUNT WINDS EASE...LOWS MAY ALSO
APPROACH RECORD LEVELS AS THE NEXT COLD POCKET OF AIR MOVES OVER
THE AREA /850MB TEMPS OF -15C TO -17C/. THIS NEXT COLD SURGE
ACTUALLY REORIENTS THE LOW-LEVEL WINDS TO MORE NORTHERLY AND THUS
LOOKS TO PRESENT AT LEAST THE POTENTIAL FOR LAKE EFFECT SNOW TO
SHIFT TOWARD NORTHWEST INDIANA WED NIGHT INTO THU. HAVE UPPED
CHANCES THERE AND CERTAINLY ACCUMULATING SNOW OF A FEW INCHES OR
MORE COULD BE REALIZED IF A FOCUSED AREA DEVELOPS...WHICH SUCH
DETAILS BEING DIFFICULT TO DETERMINE AT THIS FORECAST DISTANCE.
THURSDAY WILL BEGIN TO SEE MARGINAL MODIFICATION IN TEMPERATURES.
BEYOND...WITH THE ACTIVE SHORT TERM NOT OVERLY MUCH TIME SPENT ON
THIS FORECAST PERIOD. THE PATTERN LOOKS TO REMAIN BLOCKED OVER THE
WEEKEND...WITH CONFIDENCE INCREASING SOMEWHAT THAT THE MAIN STORM
TRACK WILL BE TO THE SOUTH OF THE AREA AND GENERAL HIGH PRESSURE
IN THE REGION. HIGH TEMPERATURES LOOK TO BE 5 TO 10 DEGREES BELOW
NORMAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* CIGS GRADUALLY LIFTING FROM LOW-END MVFR EARLY THIS EVENING.
* WEST WINDS VERY QUICKLY RAMPING UP WITH GUSTS TO 30 KTS BY EARLY
EVENING.
* ISOLATED SNOW SHOWERS BY MID-EVENING...THOUGH OF SHORT DURATION
AND FAIRLY LOW PROBABILITY OF DIRECTLY IMPACTING ANY PARTICULAR
TERMINAL.
RATZER
//DISCUSSION...UPDATED 18Z...
RADAR IMAGERY AND AREA OBSERVATIONS SHOW MIXED PRECIPITATION ACROSS
MUCH OF NORTHERN ILLINOIS...IN THE FORM OF LIGHT SNOW...RAIN...AND
DRIZZLE. A POCKET OF SLIGHTLY WARMER AIR ALOFT LIES BETWEEN ORD/MDW
EARLY THIS AFTERNOON WITH SN ON THE COLD SIDE (ORD) AND RAIN ON THE
WARM SIDE (MDW). EXPECT THIS LINE TO SHIFT EAST THROUGH THE EVENING
WITH SNOW BECOMING MORE PREVALENT FOR THE AREA TERMINALS. BASED ON
EXTRAPOLATION OF CURRENT RADAR TRENDS AND MOVEMENT OF UPPER LEVEL
TROUGH...EXPECT PRECIP TO TAPER FOR RFD AROUND 20Z...AND THE CHICAGO
TERMINALS AROUND 21Z. WITH THE LOSS OF DEEP MOISTURE BEHIND THE
UPPER WAVE...EXPECT PRECIP TO TAPER TO DRIZZLE WITH PERHAPS A FEW
FLURRIES MIXED IN AT TIMES. THIS COINCIDES WITH THE PASSAGE OF
A COLD FRONT WHICH WILL SWING WINDS TO WESTERLY. DRIER AIR AND
STEEPENING LOW LEVEL LAPSE RATES SHOULD LEAD TO SOME IMPROVEMENT IN
CIGS AND HELP DIMINISH THE MISTY CONDITIONS....BUT ALSO LOOKING AT
SOME POTENTIAL FOR A FEW WEAK INSTABILITY SNOW SHOWERS TO DEVELOP.
CONFIDENCE ON THE COVERAGE AND IMPACTS IS LOW AT THIS TIME...SO WILL
JUST MAINTAIN MENTION OF P6SM -SHSN THIS EVENING. THE OTHER CONCERN
FOR THE EARLY EVENING WILL BE WINDS SHARPLY INCREASING. AS
MENTIONED...INCREASING LOW LEVEL LAPSE RATES WILL TAP INTO STRONGER
WINDS ALOFT...COMBINED WITH AN AREA OF STRONG PRESSURE RISES TO PUSH
ACROSS THE AREA...EXPECT WINDS TO VERY QUICKLY INCREASE AND SHOULD
TOP OUT WITH GUSTS INTO THE LOW 30 KT RANGE AND LASTING THROUGH THE
OVERNIGHT HOURS.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* MEDIUM TO HIGH CONFIDENCE IN CIG TRENDS...MEDIUM CONFIDENCE IN
TIMING.
* HIGH CONFIDENCE IN WINDS.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH SUNDAY...MAINLY VFR...GUSTY WEST WINDS
TUESDAY NIGHT AND WEDNESDAY.
MDB
&&
.MARINE...
222 PM CDT
LOW PRESSURE SPINNING SLOWLY THROUGH THE NORTHERN GREAT LAKES
TONIGHT THROUGH MIDWEEK WILL PUSH AN UNNECESSARILY COLD COLD FRONT
ACROSS LAKE MICHIGAN THIS EVENING. WINDS WILL TURN SOUTHWEST AND
THEN WEST BEHIND THE FRONT AND INCREASE STEADILY THROUGH THE
EVENING.
HAVE ELECTED TO CONTINUE THE GALE WARNING FOR THE SOUTHERN
TWO THIRDS OF THE LAKE AND ALSO TO MOVE UP THE START TIME FOR THE
MIDDLE THIRD SO THAT IT MATCHES THE ORIGINAL START TIME FOR THE
SOUTHERN THIRD. STILL THINK THE NORTHERN THIRD WILL BE CLOSE ENOUGH
TO THE LOW ITSELF TO SEE WEAKER WINDS AND GUSTS...THOUGH LOCAL AREAS
COULD RECEIVE PERIODIC GALE FORCE GUSTS. UNUSUAL FOR MARCH...THERE
IS ALSO A POSSIBILITY OF FREEZING SPRAY WITH THE COLD AND GUSTY
WINDS BEHIND THE FRONT TONIGHT AND TOMORROW.
WINDS WILL TURN NORTHWEST BY WEDNESDAY AND DIMINISH SOMEWHAT...BUT
COLD AIR WILL REMAIN IN PLACE THROUGH THE WEEK.
LENNING
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...10 PM
MONDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
356 PM CDT MON MAR 18 2013
.DISCUSSION...
345 PM CDT
WHILE THE TRUE VERNAL EQUINOX ARRIVES WEDNESDAY...AND WE ARE THREE
WEEKS INTO METEOROLOGICAL WINTER...THE MAIN WEATHER HEADLINE THIS
WEEK WILL BE HOW UNSPRING-LIKE THE TEMPERATURES WILL BE. THIS
PRESENTS THE MAIN FORECAST CHALLENGE...ALONG WITH ANY SMALL
CHANCES FOR SNOW SHOWERS.
SYNOPSIS AND LATE THIS AFTERNOON...THE POTENT UPPER LEVEL LOW IS
MOVING EAST ACROSS MN THIS AFTERNOON...WITH THE MID-LEVEL JET AND
A VORT LOBE OF THE SYSTEM RUSHING EASTWARD OVER NORTHERN IL.
ENHANCEMENT ON THE LEADING EDGE OF THESE STEEPER MID-LEVEL LAPSE
RATES AND CONVERGENCE IS SEEN IN SNOW SHOWERS TRAVERSING NORTHEAST
ILLINOIS AS OF 3 PM. SPOTTIER HEAVIER SNOWFALL RATES WILL BE SEEN
IN THIS ACTIVITY AS IT DEPARTS. THE SURFACE ARCTIC FRONT OF THIS
SYSTEM IS CROSSING THE MISSISSIPPI RIVER AND WILL MOVE THROUGH THE
ENTIRE CWA BETWEEN 5 AND 9 PM. THIS WILL TURN THE SYNOPTIC PATTERN
TO ONE OF NORTHWEST FLOW AND COLD WHICH WILL CONTINUE TO REINFORCE
ITSELF THROUGH THE WEEK AS THE UPPER AND SURFACE LOWS EXPAND AND
SLOW ACROSS THE CENTRAL AND EASTERN GREAT LAKES. NUMEROUS SHORT
WAVE IMPULSES ARE EXPECTED TO RIDE AROUND THIS FEATURE WITH
MINIMAL CAUSES FOR SNOW...BUT EACH DRIVING COLD SURGES BACK INTO
THE AREA.
TONIGHT...SHORT TERM GUIDANCE IS IN GOOD AGREEMENT ON THE TIMING
OF THE ARCTIC FRONT THIS EVENING...ALONG WITH AGREEING THAT THE
STEEPENING OF THE LOW-LEVEL LAPSE RATES WILL LIKELY PRODUCE
SURFACE-BASED INSTABILITY. FORECAST SOUNDINGS FROM THE RAP YIELD
AROUND 50 J/KG OF MLCAPE ALONG AND IMMEDIATELY BEHIND THE FRONT.
THE SATURATED DEPTH AT THE TOP OF THIS MIXED LAYER IS QUITE
SHALLOW BUT MOST CONVECTIVE-ALLOWING ARW AND WRF GUIDANCE DO
CONTINUE TO PRODUCE A SPATTERING OF HIGHER REFLECTIVITY INDICATIVE
OF SNOW SHOWERS. WILL CARRY FLURRIES WITH A MENTION OF ISOLATED TO
SCATTERED SNOW SHOWERS.
THE FRONT WILL BRING BOTH STRONG HEIGHT AND PRESSURE RISES WHICH
ARE LINED UP WELL WITH A UNIDIRECTIONAL WIND COLUMN IN THE LOW-
LEVELS. THE TOP OF THE MIXED LAYER ON THE LATEST RAP GUIDANCE AS
WELL AS LOCAL ARW DOES YIELD 40 MPH GUSTS THIS EVENING. HAVE
INCLUDED SUCH GUSTS IMMEDIATELY BEHIND THE FRONT AND WOULD NOT BE
SURPRISED IF SOME PLACES IN THE SOUTHWEST FORECAST AREA COME IN A
BIT HIGHER. IF SNOW SHOWERS DO DEVELOP...SOME NOTABLE REDUCTIONS
IN VISIBILITY MAY BE SEEN DUE TO THE COMBINATION OF WINDS AND
SNOWFALL. WITH TEMPERATURES FALLING QUICKLY...WIND CHILLS IN THE
NORTHWEST FORECAST AREA LOOK TO ALREADY BE IN THE SINGLE DIGITS
BY 9 PM THIS EVENING. THIS DEGREE OF COLD AIR WILL SWEEP OVER THE
ENTIRE FORECAST AREA WITH EARLY MORNING TEMPERATURES IN THE MID
TEENS TOWARD ROCKFORD TO AROUND 20 EAST. THESE ARE ABOUT 10 TO 15
DEGREES BELOW NORMAL.
TUESDAY AND TUESDAY NIGHT...UPPER LEVEL HEIGHTS WILL NOT RISE ANY
ON TUE WITH CYCLONIC FLOW IN COMPLETE CONTROL. HOWEVER...MOST
SHORT WAVE ENERGY IS LIKELY TO REMAIN TO THE NORTH AND EAST...SO
IT IS POSSIBLE TO SEE A LITTLE SCATTERING IN SOUTHERN AREAS. WITH
THE FIRST COLD POCKET OF AIR SHIFTING SLIGHTLY EAST OF THE
AREA...TEMPERATURES SHOULD MAKE IT BACK CLOSE TO TODAYS HIGHS.
WIND CHILLS WILL REMAIN IN THE MID TEENS TO MID 20S HOWEVER. A
SECOND COLD FRONT PUSHES THROUGH TOMORROW NIGHT ASSOCIATED WITH A
SHORT WAVE ROTATING AROUND THE PARENT LOW. THIS APPEARS STARVED
FOR DEEP MOISTURE BUT THE COLD AIR WILL BRING LOW TEMPERATURES
EVEN COOLER TUE NIGHT AND WIND CHILLS BELOW ZERO FOR WED MORNING.
WEDNESDAY AND THURSDAY...DUE TO SUCCESSIVE COLD FRONTS AND LIKELY
BROKEN TO OVERCAST STRATOCU GIVEN FORECAST SOUNDINGS FOR
WED...THIS SHOULD BE THE DAY WITH THE COLDEST HIGH TEMPERATURE. IN
FACT...THE HIGH TEMPERATURE FORECAST /22/ REMAINS A TIED RECORD
LOW MAXIMUM FOR ROCKFORD ON MARCH 20TH. BACKWARD PARCEL
TRAJECTORIES FROM THE GFS IN THIS TIME INDICATE THE AIR MASS
SOURCE REGION TO BE THE NORTHERN PROVINCES OF CANADA...NOT A
TYPICAL SOURCE REGION FOR LATE MARCH FOR THIS AREA. DEPENDING ON
CLOUD COVER WED NIGHT AND THE AMOUNT WINDS EASE...LOWS MAY ALSO
APPROACH RECORD LEVELS AS THE NEXT COLD POCKET OF AIR MOVES OVER
THE AREA /850MB TEMPS OF -15C TO -17C/. THIS NEXT COLD SURGE
ACTUALLY REORIENTS THE LOW-LEVEL WINDS TO MORE NORTHERLY AND THUS
LOOKS TO PRESENT AT LEAST THE POTENTIAL FOR LAKE EFFECT SNOW TO
SHIFT TOWARD NORTHWEST INDIANA WED NIGHT INTO THU. HAVE UPPED
CHANCES THERE AND CERTAINLY ACCUMULATING SNOW OF A FEW INCHES OR
MORE COULD BE REALIZED IF A FOCUSED AREA DEVELOPS...WHICH SUCH
DETAILS BEING DIFFICULT TO DETERMINE AT THIS FORECAST DISTANCE.
THURSDAY WILL BEGIN TO SEE MARGINAL MODIFICATION IN TEMPERATURES.
BEYOND...WITH THE ACTIVE SHORT TERM NOT OVERLY MUCH TIME SPENT ON
THIS FORECAST PERIOD. THE PATTERN LOOKS TO REMAIN BLOCKED OVER THE
WEEKEND...WITH CONFIDENCE INCREASING SOMEWHAT THAT THE MAIN STORM
TRACK WILL BE TO THE SOUTH OF THE AREA AND GENERAL HIGH PRESSURE
IN THE REGION. HIGH TEMPERATURES LOOK TO BE 5 TO 10 DEGREES BELOW
NORMAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* IFR CIGS LIFTING TO MVFR LATE AFTERNOON OR EARLY EVENING.
* MIXED PRECIPITATION/MISTY CONDITIONS WITH VSBY BOUNCING
AROUND...UNDER 2SM AT TIMES...AND 4-5SM AT TIMES...IMPROVING
LATE THIS AFTERNOON.
* WINDS VERY QUICKLY RAMPING UP WITH GUSTS TO 30 KTS LATE
AFTERNOON/EARLY EVENING.
BMD
//DISCUSSION...UPDATED 18Z...
RADAR IMAGERY AND AREA OBSERVATIONS SHOW MIXED PRECIPITATION ACROSS
MUCH OF NORTHERN ILLINOIS...IN THE FORM OF LIGHT SNOW...RAIN...AND
DRIZZLE. A POCKET OF SLIGHTLY WARMER AIR ALOFT LIES BETWEEN ORD/MDW
EARLY THIS AFTERNOON WITH SN ON THE COLD SIDE (ORD) AND RAIN ON THE
WARM SIDE (MDW). EXPECT THIS LINE TO SHIFT EAST THROUGH THE EVENING
WITH SNOW BECOMING MORE PREVALENT FOR THE AREA TERMINALS. BASED ON
EXTRAPOLATION OF CURRENT RADAR TRENDS AND MOVEMENT OF UPPER LEVEL
TROUGH...EXPECT PRECIP TO TAPER FOR RFD AROUND 20Z...AND THE CHICAGO
TERMINALS AROUND 21Z. WITH THE LOSS OF DEEP MOISTURE BEHIND THE
UPPER WAVE...EXPECT PRECIP TO TAPER TO DRIZZLE WITH PERHAPS A FEW
FLURRIES MIXED IN AT TIMES. THIS COINCIDES WITH THE PASSAGE OF
A COLD FRONT WHICH WILL SWING WINDS TO WESTERLY. DRIER AIR AND
STEEPENING LOW LEVEL LAPSE RATES SHOULD LEAD TO SOME IMPROVEMENT IN
CIGS AND HELP DIMINISH THE MISTY CONDITIONS....BUT ALSO LOOKING AT
SOME POTENTIAL FOR A FEW WEAK INSTABILITY SNOW SHOWERS TO DEVELOP.
CONFIDENCE ON THE COVERAGE AND IMPACTS IS LOW AT THIS TIME...SO WILL
JUST MAINTAIN MENTION OF P6SM -SHSN THIS EVENING. THE OTHER CONCERN
FOR THE EARLY EVENING WILL BE WINDS SHARPLY INCREASING. AS
MENTIONED...INCREASING LOW LEVEL LAPSE RATES WILL TAP INTO STRONGER
WINDS ALOFT...COMBINED WITH AN AREA OF STRONG PRESSURE RISES TO PUSH
ACROSS THE AREA...EXPECT WINDS TO VERY QUICKLY INCREASE AND SHOULD
TOP OUT WITH GUSTS INTO THE LOW 30 KT RANGE AND LASTING THROUGH THE
OVERNIGHT HOURS.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM TO HIGH CONFIDENCE IN CIG TRENDS...MEDIUM CONFIDENCE IN
TIMING.
* MEDIUM CONFIDENCE IN PRECIP TYPE/TIMING.
* LOW TO MEDIUM CONFIDENCE IN VSBY TRENDS.
* MEDIUM TO HIGH CONFIDENCE IN WINDS.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH SUNDAY...MAINLY VFR...GUSTY WEST WINDS
TUESDAY NIGHT AND WEDNESDAY.
MDB
&&
.MARINE...
222 PM CDT
LOW PRESSURE SPINNING SLOWLY THROUGH THE NORTHERN GREAT LAKES
TONIGHT THROUGH MIDWEEK WILL PUSH AN UNNECESSARILY COLD COLD FRONT
ACROSS LAKE MICHIGAN THIS EVENING. WINDS WILL TURN SOUTHWEST AND
THEN WEST BEHIND THE FRONT AND INCREASE STEADILY THROUGH THE
EVENING.
HAVE ELECTED TO CONTINUE THE GALE WARNING FOR THE SOUTHERN
TWO THIRDS OF THE LAKE AND ALSO TO MOVE UP THE START TIME FOR THE
MIDDLE THIRD SO THAT IT MATCHES THE ORIGINAL START TIME FOR THE
SOUTHERN THIRD. STILL THINK THE NORTHERN THIRD WILL BE CLOSE ENOUGH
TO THE LOW ITSELF TO SEE WEAKER WINDS AND GUSTS...THOUGH LOCAL AREAS
COULD RECEIVE PERIODIC GALE FORCE GUSTS. UNUSUAL FOR MARCH...THERE
IS ALSO A POSSIBILITY OF FREEZING SPRAY WITH THE COLD AND GUSTY
WINDS BEHIND THE FRONT TONIGHT AND TOMORROW.
WINDS WILL TURN NORTHWEST BY WEDNESDAY AND DIMINISH SOMEWHAT...BUT
COLD AIR WILL REMAIN IN PLACE THROUGH THE WEEK.
LENNING
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...10 PM
MONDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
304 PM CDT MON MAR 18 2013
.DISCUSSION...
1055 AM CDT
CONTINUING TO MONITOR OBSERVATIONAL AND SHORT TERM GUIDANCE AS
LATE SEASON LIGHT WINTRY PRECIP EVENT CONTINUES. WE HAVE HOWEVER
LET THE ADVISORY END AT 11 AM AS INITIALLY PLANNED...DUE MAINLY
TO THE THREAT OF APPRECIABLE FREEZING PRECIPITATION HAVING ENDED.
ONE SHORT WAVE IMPULSE IS CURRENTLY PROGRESSING NORTHEAST OVER
LAKE MI AND WAS RESPONSIBLE FOR OUR EARLY MORNING LIGHT
ACCUMULATIONS. THE PRIMARY UPPER WAVE IS APPROACHING QUICKLY ACROSS
IA AND IS VERY WELL-DEFINED ON THE WATER VAPOR CHANNEL. WEAK WARM
AND MOIST ADVECTION ALOFT CONTINUES ACROSS THE SOUTHERN AND
EASTERN AREA...BUT A GOOD PART OF THE MOISTURE TRANSPORT WAS AND
CONTINUES TO BE ROBBED BY OHIO VALLEY/LOWER MISSISSIPPI VALLEY
CONVECTION. STILL GETTING SPOTTER REPORTS AND PUBLIC REPORTS
THROUGH THE NSSL MPING APPLICATION OF LIGHT FREEZING PRECIPITATION
ACROSS CHICAGO...AND RECENT AMDAR SOUNDINGS DO SUPPORT A LIGHT MIX.
WITH CONTINUED LIGHT ARCED RADAR ECHOES OF AN ISENTROPIC ASCENT
NATURE SHOWING UP ACROSS CHICAGO INTO NORTHWEST INDIANA...WILL
CONTINUE THE MENTION FOR LIGHT FREEZING PRECIP/SLEET IN THE
FORECAST FOR THOSE AREAS INTO EARLY AFTERNOON. WITH THE LIGHT
RATES AND TEMPERATURES HAVING INCHED UP TO THE 30 TO 32
MARK...EXPECTING ANY ICE ACCUMULATION TO BE LIGHT.
AS THE UPPER WAVE PROGRESSES IN...ELEVATED STEEP LAPSE RATES IN
TANDEM WITH DEEPER MOISTURE SUPPORT THE POTENTIAL FOR MODEST
SNOW/SNOW SHOWERS MOVING ACROSS NORTHERN IL...ESPECIALLY ALONG AND
NORTH OF I-88. THIS POTENTIAL IS VERIFIED WITH NUMEROUS EASTERN IA
LOCATIONS HAVING REPORTED VISIBILITY UNDER 1SM. HIGH RES
REFLECTIVITY PRODUCING MODELS SHOW CONTINUED ENHANCEMENT AS THIS
AREA PROGRESSES EAST ACROSS NORTHERN IL THROUGH EARLY TO MID
AFTERNOON WHICH MAKES SENSE WITH THE AFOREMENTIONED FORCING.
SCATTERED HEAVY RATES ARE POSSIBLE AT TIMES...ESPECIALLY IN THE WI
BORDER COUNTIES. DO NOT WANT TO DOWNPLAY TEMPORARY IMPACTS TO
TRAVEL ESPECIALLY WITH BURSTS OF HEAVIER RATES...BUT WILL MENTION
THAT IN AN SPS AS OPPOSED TO EXTENDING THE ADVISORY AS ADDITIONAL
SNOWFALL ACCUMULATIONS LOOK TO BE ON THE ORDER OF ONE TO MAYBE TWO
INCHES AT MOST AND THE FREEZING PRECIP THREAT ENDING FROM WEST TO
EAST.
MTF
//PREV DISCUSSION...
529 AM CDT
A WINTER ADVISORY HAS BEEN ISSUED FOR A PORTION OF NORTHERN
ILLINOIS AND NORTHWEST INDIANA THROUGH 11 AM...WITH SLEET AND
FREEZING RAIN THE MAIN CONCERNS.
LATEST RADAR IMAGERY CONTINUES TO SHOW PRECIP SHIELD BLOSSOMING
EARLY THIS MORNING AS LARGE SCALE FORCING INCREASES ACROSS THE
AREA. THIS FORCING COINCIDING WITH A THERMAL PROFILE SUPPORTIVE OF
A WINTRY MIX...HAS RESULTED IN WIDESPREAD SLEET AND FREEZING RAIN
BEING REPORTED. AT THE OFFICE HERE IN ROMEOVILLE...MORE SLEET
ACCUMULATION HAS BEEN NOTICED OVER THE LAST HOUR. THIS SLEET
ACCUMULATION AS WELL AS THE FURTHER BLOSSOMING OF THE PRECIP
SHIELD IS WHAT HAS PROMPTED THE ADVISORY. ALTHOUGH ANY SNOW/SLEET
ACCUMULATION WILL REMAIN RATHER MINOR AROUND AN INCH...ITS ONCE
AGAIN THE SLEET ACCUMULATION COINCIDING WITH LIGHT FREEZING RAIN
WHICH IS THE MAIN CONCERN...CONCERNS OF SLIPPERY CONDITIONS FOR
THE MORNING COMMUTE. STILL EXPECT FURTHER SNOW ACCUMULATION LATER
THIS MORNING INTO THE AFTERNOON...BUT WITH SNOW THE LIKELY PRECIP
TYPE.
RODRIGUEZ
//PREV DISCUSSION...
406 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH A
WINTRY MIX OF PRECIP ONGOING...AND THEN CONTINUING THROUGH THE
REMAINDER OF THE DAY WITH SNOW LIKELY ACROSS THE NORTHERN THIRD OF
THE CWA WHILE A RAIN/SNOW MIX FURTHER SOUTH TOWARDS THE I80
CORRIDOR...AND THEN ALL RAIN ACROSS THE SOUTHERN TIER OF COUNTIES.
LATEST RADAR IMAGERY IS DEPICTING AN AREA OF PRECIPITATION
SPREADING NORTH ACROSS PARTS OF NORTHEAST ILLINOIS AND NORTHWEST
INDIANA AS AN MID LEVEL WAVE TRACKS NORTHEAST ACROSS THE REGION.
LATEST REPORTS CONTINUE TO SUPPORT A WINTRY MIX THAT HAS BEEN
ANTICIPATED WITH SNOW OR SLEET FALLING ON THE NORTHERN FRINGE OF
THIS PRECIP SHIELD FROM STREATOR IN ILLINOIS EAST TO RENSSELAER IN
INDIANA...WHILE A RAIN SNOW MIX HAD BEEN REPORTED JUST SOUTH OF
THIS LINE. OVER THE NEXT COUPLE OF HOURS THIS TREND WILL LIKELY
CONTINUE AS THIS WINTRY MIX MOVES NORTH TOWARD THE CHICAGO METRO
AREA. ALTHOUGH WEAK...LATEST RAP ANALYSIS IS SHOWING SOME WAA
AIDING IN THIS DEVELOPMENT AND EXPECT THIS WEAK WAA TO FURTHER AID
THIS MORNING UNTIL MORE LARGE SCALE SUPPORT ARRIVES FROM THE WEST.
EXPECT SNOW OR SLEET WITH ONLY MINOR ACCUMULATIONS INITIALLY EARLY
THIS MORNING ALONG AND NORTH OF INTERSTATE 80...JUST SOUTH OF THE
INTERSTATE 80 CORRIDOR A RAIN SNOW MIX WILL BE LIKELY CONTINUE.
SURFACE TEMPS THIS MORNING HAVE BEEN SLOWLY FALLING WITH CURRENT
TEMPS AT OR JUST BELOW FREEZING ACROSS MUCH OF THE CWA. IN THOSE
AREAS WHERE LIGHT RAIN DOES OCCUR...THESE SURFACE TEMPERATURES
WILL SUPPORT THE POTENTIAL FOR BRIDGES AND ELEVATED ROADWAYS TO
ACCUMULATE A THIN LAYER OF ICING. ALTHOUGH THIS WINTRY MIX HAD
BEEN FALLING OVER THE LAST COUPLE OF HOURS...REPORTS HAD NOT
INDICATED ANY WIDESPREAD SLIPPERY CONDITIONS BUT WITH ROADS
REMAINING ONLY WET AT THAT TIME. WOULD SUSPECT THAT SLIPPERY
CONDITIONS ARE CURRENTLY DEVELOPING AND COULD POSSIBLY CONTINUE TO
DEVELOP OVER THE NEXT COUPLE OF HOURS. OF GREATEST CONCERN AT THIS
TIME FOR THESE SLIPPERY CONDITIONS WOULD BE THE I80 CORRIDOR WHERE
CURRENTLY THE STRONGEST RETURNS ON RADAR ARE LOCATED AS WELL AS
WITH SURFACE TEMPS JUST BELOW FREEZING. HAVE REISSUED AN SPS AT
THIS TIME FOR THOSE AREAS...WHILE NOT ISSUING ANY OTHER HEADLINES
AT THIS TIME. FORCING FOR THIS CURRENT PRECIP ACROSS THE CWA
SHOULD EXIT OVER THE NEXT COUPLE OF HOURS...WITH LATEST SHORT TERM
GUIDANCE SHOWING A DIMINISHING TREND WITHIN THE OVERALL EXTENT OF
THIS PRECIP. RESIDENCE TIME FOR ANY FURTHER LINGERING PRECIP IN
THESE AREAS SHOULD BE LIMITED THIS MORNING...AS THIS PRECIP AXIS
SLOWLY LIFTS NORTH. ALTHOUGH A DIMINISHING TREND HERE IN THE NEAR
TERM IS LIKELY...ONCE AGAIN STILL ANTICIPATE A NORTHWARD PUSH OF
THIS PRECIP.
LARGE SCALE FORCING FOR ASCENT WILL INCREASE THROUGH MID MORNING
AS THE CURRENT UPPER LEVEL TROUGH JUST TO THE WEST PUSHES EAST.
THIS IS ALREADY BEGINNING TO OCCUR OVER AREAS IN EASTERN IOWA
WHERE LIGHT RETURNS ARE BEGINNING TO SHOW UP ON RADAR. EXPECT
FURTHER DEVELOPMENT THROUGH MID TO LATE MORNING WITH A MIXED BAG
OF PRECIPITATION STILL LIKELY. ALTHOUGH...LATEST GUIDANCE IS
SHOWING THAT COLDER AIR WILL BE IN PLACE FURTHER SOUTH ACROSS THE
CWA THAN PREVIOUSLY ANTICIPATED WITH THE NUDGE OF WARMER AIR ALOFT
NOT AS PRONOUNCED FOR THIS MORNING OR MOST OF THE DAY...WITH
LATEST AMDAR SOUNDINGS SUPPORTED THESE THERMAL PROFILES. WITH THAT
IN MIND...HAVE SNOW OR SLEET POSSIBLE THROUGH MID MORNING FOR THE
NORTHERN HALF OF THE CWA ACROSS NORTH CENTRAL AND NORTHEAST
ILLINOIS WITH MORE LIQUID TYPE PRECIP EXPECTED FURTHER SOUTH.
SURFACE TEMPS WILL BE RISING THROUGH MID MORNING WITH ANY FURTHER
THREAT OF FREEZING RAIN IN THE CURRENT LOCATIONS BECOMING LESS
LIKELY. AS THIS UPPER LEVEL TROUGH SWINGS ACROSS THIS SNOW/SLEET
AND THEN SNOW THROUGH MID DAY AND EARLY AFTERNOON...DO THINK THERE
WILL BE SOME MINOR ACCUMULATIONS FOR AREAS ALONG AND NORTH OF THE
INTERSTATE 88 CORRIDOR INCLUDING THE WEST/NORTHWEST/NORTHERN
SUBURBS OF CHICAGO. ONE TO TWO INCHES WILL BE POSSIBLE NEAR THE
WISCONSIN BORDER WITH THREE INCHES AN OUTSIDE POSSIBILITY FOR
ISOLATED LOCATIONS...AND AROUND AN INCH FURTHER SOUTH. A TREND
TOWARDS MORE DRIZZLE WILL BE POSSIBLE BY MID AFTERNOON BUT AS THIS
OCCURS...MUCH COLDER AIR WILL BE SWEEPING THROUGH THE CWA. THIS
COULD HELP FOR FURTHER CRYSTALS TO DEVELOP AND HELP LIGHT SNOW TO
LINGER AROUND INTO THE AFTERNOON AND EARLY EVENING BUT WITH LITTLE
OR NO ADDITIONAL ACCUMULATION LIKELY. COLDER TEMPS STILL ON PAR
FOR THIS WEEK...STARTING OFF TONIGHT WITH LOW TO MID TEENS
POSSIBLE ACROSS MUCH OF THE CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* IFR CIGS LIFTING TO MVFR LATE AFTERNOON OR EARLY EVENING.
* MIXED PRECIPITATION/MISTY CONDITIONS WITH VSBY BOUNCING
AROUND...UNDER 2SM AT TIMES...AND 4-5SM AT TIMES...IMPROVING
LATE THIS AFTERNOON.
* WINDS VERY QUICKLY RAMPING UP WITH GUSTS TO 30 KTS LATE
AFTERNOON/EARLY EVENING.
BMD
//DISCUSSION...UPDATED 18Z...
RADAR IMAGERY AND AREA OBSERVATIONS SHOW MIXED PRECIPITATION ACROSS
MUCH OF NORTHERN ILLINOIS...IN THE FORM OF LIGHT SNOW...RAIN...AND
DRIZZLE. A POCKET OF SLIGHTLY WARMER AIR ALOFT LIES BETWEEN ORD/MDW
EARLY THIS AFTERNOON WITH SN ON THE COLD SIDE (ORD) AND RAIN ON THE
WARM SIDE (MDW). EXPECT THIS LINE TO SHIFT EAST THROUGH THE EVENING
WITH SNOW BECOMING MORE PREVALENT FOR THE AREA TERMINALS. BASED ON
EXTRAPOLATION OF CURRENT RADAR TRENDS AND MOVEMENT OF UPPER LEVEL
TROUGH...EXPECT PRECIP TO TAPER FOR RFD AROUND 20Z...AND THE CHICAGO
TERMINALS AROUND 21Z. WITH THE LOSS OF DEEP MOISTURE BEHIND THE
UPPER WAVE...EXPECT PRECIP TO TAPER TO DRIZZLE WITH PERHAPS A FEW
FLURRIES MIXED IN AT TIMES. THIS COINCIDES WITH THE PASSAGE OF
A COLD FRONT WHICH WILL SWING WINDS TO WESTERLY. DRIER AIR AND
STEEPENING LOW LEVEL LAPSE RATES SHOULD LEAD TO SOME IMPROVEMENT IN
CIGS AND HELP DIMINISH THE MISTY CONDITIONS....BUT ALSO LOOKING AT
SOME POTENTIAL FOR A FEW WEAK INSTABILITY SNOW SHOWERS TO DEVELOP.
CONFIDENCE ON THE COVERAGE AND IMPACTS IS LOW AT THIS TIME...SO WILL
JUST MAINTAIN MENTION OF P6SM -SHSN THIS EVENING. THE OTHER CONCERN
FOR THE EARLY EVENING WILL BE WINDS SHARPLY INCREASING. AS
MENTIONED...INCREASING LOW LEVEL LAPSE RATES WILL TAP INTO STRONGER
WINDS ALOFT...COMBINED WITH AN AREA OF STRONG PRESSURE RISES TO PUSH
ACROSS THE AREA...EXPECT WINDS TO VERY QUICKLY INCREASE AND SHOULD
TOP OUT WITH GUSTS INTO THE LOW 30 KT RANGE AND LASTING THROUGH THE
OVERNIGHT HOURS.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM TO HIGH CONFIDENCE IN CIG TRENDS...MEDIUM CONFIDENCE IN
TIMING.
* MEDIUM CONFIDENCE IN PRECIP TYPE/TIMING.
* LOW TO MEDIUM CONFIDENCE IN VSBY TRENDS.
* MEDIUM TO HIGH CONFIDENCE IN WINDS.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH SUNDAY...MAINLY VFR...GUSTY WEST WINDS
TUESDAY NIGHT AND WEDNESDAY.
MDB
&&
.MARINE...
222 PM CDT
LOW PRESSURE SPINNING SLOWLY THROUGH THE NORTHERN GREAT LAKES
TONIGHT THROUGH MIDWEEK WILL PUSH AN UNNECESSARILY COLD COLD FRONT
ACROSS LAKE MICHIGAN THIS EVENING. WINDS WILL TURN SOUTHWEST AND
THEN WEST BEHIND THE FRONT AND INCREASE STEADILY THROUGH THE
EVENING.
HAVE ELECTED TO CONTINUE THE GALE WARNING FOR THE SOUTHERN
TWO THIRDS OF THE LAKE AND ALSO TO MOVE UP THE START TIME FOR THE
MIDDLE THIRD SO THAT IT MATCHES THE ORIGINAL START TIME FOR THE
SOUTHERN THIRD. STILL THINK THE NORTHERN THIRD WILL BE CLOSE ENOUGH
TO THE LOW ITSELF TO SEE WEAKER WINDS AND GUSTS...THOUGH LOCAL AREAS
COULD RECEIVE PERIODIC GALE FORCE GUSTS. UNUSUAL FOR MARCH...THERE
IS ALSO A POSSIBILITY OF FREEZING SPRAY WITH THE COLD AND GUSTY
WINDS BEHIND THE FRONT TONIGHT AND TOMORROW.
WINDS WILL TURN NORTHWEST BY WEDNESDAY AND DIMINISH SOMEWHAT...BUT
COLD AIR WILL REMAIN IN PLACE THROUGH THE WEEK.
LENNING
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...10 PM
MONDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
300 PM CDT MON MAR 18 2013
.DISCUSSION...
ISSUED 300 PM CDT MON MAR 18 2013
SHORT TERM...TODAY THROUGH THURSDAY NIGHT
PATCHY DRIZZLE NE OF LINCOLN THIS AFTERNOON SHOULD END BY SUNSET
SO GOING WITH A DRY FORECAST TONIGHT AS 1002 MB LOW PRESSURE OVER NE
INDIANA PULLS AWAY FROM CENTRAL IL. CLEARING OF LOW CLOUDS WORKING
EASTWARD TOWARD WEST CENTRAL IL AT MID AFTERNOON TO NEAR QUINCY
AND EXPECT THESE LOW CLOUDS TO DECREASE FROM WEST TO EAST DURING
THE EVENING. THOUGH STRONG UPPER LEVEL TROF TO SPREAD MORE LOW
CLOUDS FROM IA ACROSS AREAS FROM I-74 NORTH...BUT DECREASE THERE
AS WELL DURING OVERNIGHT. COLDER LOWS RANGE FROM AROUND 20F NORTH
OF I-72 TO THE MID 20S IN SE IL. MOSTLY SUNNY SKIES OVERALL TUE
THOUGH SOME INCREASING CLOUDS IN THE AFTERNOON ESPECIALLY SW AREAS
FROM WEAK CLIPPER RACING ACROSS THE MO VALLEY AND KEEPING THE
BRUNT OF ITS LIGHT PRECIPITATION SW OF CENTRAL IL. HAVE CHANCE OF
FLURRIES OVER SOUTHERN AREAS OVERNIGHT TUE NIGHT INTO WED MORNING.
EVEN COLDER AIRMASS ARRIVES WED AND WED NIGHT BEHIND THIS WEAK
CLIPPER WITH HIGHS WED IN THE UPPER 20S AND LOWER 30S CENTRAL IL
AND 33-38F IN SE IL. LOWS WED NIGHT IN THE MID TO UPPER TEENS AND
MORE TYPICAL OF JANUARY TEMPS. DRY WEATHER EXPECTED WED NIGHT
THROUGH THU NIGHT ALONG WITH BELOW NORMAL TEMPS CONTINUE WITH
HIGHS THU IN THE 30S.
LONG TERM...FRIDAY THROUGH MONDAY
12Z EXTENDED RANGE MODELS CONTINUE TO DIFFER WITH TRACK OF WEATHER
SYSTEMS AND CORRELATING QPF FIELDS THIS WEEKEND. GFS STILL APPEARS
TOO AGGRESSIVE WITH STRONGER AND QUICKER WITH DEVELOPING UPPER
LEVEL LOW INTO TN SUNDAY AFTERNOON AND TOO FAR NORTH WITH QPF INTO
CENTRAL IL. PREFER THE FURTHER SOUTH TRACK OF THE ECWMF...GEM AND
DGEX MODELS SO LOWERED THE ALLBLEND POPS THIS WEEKEND TO EITHER
DRY OR SLIGHT CHANCE AT BEST. MODELS ARE IN AGREEMENT IN KEEPING
BELOW NORMAL TEMPS DESPITE A SLOW MODERATE OF THE POLAR AIRMASS.
HIGHS REACH THE LOW TO MID 40S AND SHOULD BE AT LEAST 10 DEGREES
MILDER IN THE LOW TO MID 50S. CPC`S 8-14 DAY OUTLOOK FOR MAR
26-APR 1 CONTINUES 40-50% BELOW NORMAL TEMPERATURES AND PRECIPITATION.
07
&&
.AVIATION...
ISSUED 1258 PM CDT MON MAR 18 2013
MOST LOCATIONS IN CENTRAL AND EASTERN ILLINOIS WERE REPORTING
IFR...WITH A FEW LINGERING LIFR...CEILINGS. LOW PRESSURE IN
CENTRAL IND LIFTING TO THE NNE HAS RESULTED IN A BRISK WEST WIND
IN MOST LOCATIONS AS WELL. MOST OF THE PRECIPITATION HAS DEPARTED
THE REGION...WITH THE EXCEPTION OF LINGERING LIGHT RAIN SHOWERS
ALONG AND NORTH OF I-74. WILL KEEP THESE GOING IN THE TAFS FOR
KPIA AND KBMI EARLY THIS AFTERNOON.
THE MAIN CONCERN FROM MID-AFTERNOON AND BEYOND IS THE SKY
CONDITION AND WHEN ANY CLEARING MAY APPROACH. THE LATEST IR
SATELLITE LOOP AND SURFACE OBS INDICATED THAT CLEARING IN WESTERN
MO WAS MOVING ESE AROUND 30 MPH OR SO. THIS WOULD EXTRAPOLATE INTO
CENTRAL IL CLOSE TO 00Z...WHICH MATCHES FAIRLY WELL WITH THE
LATEST HRRR MODEL.
TAF SITES FROM KPIA-KBMI-KCMI MAY NOT CLEAR AS QUICK BECAUSE THEY
COULD END UP BEING ON THE SOUTHERN EDGE OF THE LOW CLOUD SHIELD
WITH THE SHORTWAVE TROUGH SWINGING THROUGH THE WESTERN GREAT LAKES
REGION. FOR NOW WILL KEEP AT LEAST MVFR CONDITIONS IN PLACE FOR
THESE AREAS THROUGH THE EVENING (TIL 05-06Z) AND GRADUALLY CLEAR
THE SKY OVERNIGHT.
AN INCREASING PRESSURE GRADIENT AHEAD OF THE CLEARING/SURFACE
BOUNDARY IN WESTERN MO WILL ALSO RESULT IN GUSTY WINDS FROM THE
WEST THIS AFTERNOON INTO EARLY THIS EVENING.
MILLER
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
223 PM CDT MON MAR 18 2013
.DISCUSSION...
1055 AM CDT
CONTINUING TO MONITOR OBSERVATIONAL AND SHORT TERM GUIDANCE AS
LATE SEASON LIGHT WINTRY PRECIP EVENT CONTINUES. WE HAVE HOWEVER
LET THE ADVISORY END AT 11 AM AS INITIALLY PLANNED...DUE MAINLY
TO THE THREAT OF APPRECIABLE FREEZING PRECIPITATION HAVING ENDED.
ONE SHORT WAVE IMPULSE IS CURRENTLY PROGRESSING NORTHEAST OVER
LAKE MI AND WAS RESPONSIBLE FOR OUR EARLY MORNING LIGHT
ACCUMULATIONS. THE PRIMARY UPPER WAVE IS APPROACHING QUICKLY ACROSS
IA AND IS VERY WELL-DEFINED ON THE WATER VAPOR CHANNEL. WEAK WARM
AND MOIST ADVECTION ALOFT CONTINUES ACROSS THE SOUTHERN AND
EASTERN AREA...BUT A GOOD PART OF THE MOISTURE TRANSPORT WAS AND
CONTINUES TO BE ROBBED BY OHIO VALLEY/LOWER MISSISSIPPI VALLEY
CONVECTION. STILL GETTING SPOTTER REPORTS AND PUBLIC REPORTS
THROUGH THE NSSL MPING APPLICATION OF LIGHT FREEZING PRECIPITATION
ACROSS CHICAGO...AND RECENT AMDAR SOUNDINGS DO SUPPORT A LIGHT MIX.
WITH CONTINUED LIGHT ARCED RADAR ECHOES OF AN ISENTROPIC ASCENT
NATURE SHOWING UP ACROSS CHICAGO INTO NORTHWEST INDIANA...WILL
CONTINUE THE MENTION FOR LIGHT FREEZING PRECIP/SLEET IN THE
FORECAST FOR THOSE AREAS INTO EARLY AFTERNOON. WITH THE LIGHT
RATES AND TEMPERATURES HAVING INCHED UP TO THE 30 TO 32
MARK...EXPECTING ANY ICE ACCUMULATION TO BE LIGHT.
AS THE UPPER WAVE PROGRESSES IN...ELEVATED STEEP LAPSE RATES IN
TANDEM WITH DEEPER MOISTURE SUPPORT THE POTENTIAL FOR MODEST
SNOW/SNOW SHOWERS MOVING ACROSS NORTHERN IL...ESPECIALLY ALONG AND
NORTH OF I-88. THIS POTENTIAL IS VERIFIED WITH NUMEROUS EASTERN IA
LOCATIONS HAVING REPORTED VISIBILITY UNDER 1SM. HIGH RES
REFLECTIVITY PRODUCING MODELS SHOW CONTINUED ENHANCEMENT AS THIS
AREA PROGRESSES EAST ACROSS NORTHERN IL THROUGH EARLY TO MID
AFTERNOON WHICH MAKES SENSE WITH THE AFOREMENTIONED FORCING.
SCATTERED HEAVY RATES ARE POSSIBLE AT TIMES...ESPECIALLY IN THE WI
BORDER COUNTIES. DO NOT WANT TO DOWNPLAY TEMPORARY IMPACTS TO
TRAVEL ESPECIALLY WITH BURSTS OF HEAVIER RATES...BUT WILL MENTION
THAT IN AN SPS AS OPPOSED TO EXTENDING THE ADVISORY AS ADDITIONAL
SNOWFALL ACCUMULATIONS LOOK TO BE ON THE ORDER OF ONE TO MAYBE TWO
INCHES AT MOST AND THE FREEZING PRECIP THREAT ENDING FROM WEST TO
EAST.
MTF
//PREV DISCUSSION...
529 AM CDT
A WINTER ADVISORY HAS BEEN ISSUED FOR A PORTION OF NORTHERN
ILLINOIS AND NORTHWEST INDIANA THROUGH 11 AM...WITH SLEET AND
FREEZING RAIN THE MAIN CONCERNS.
LATEST RADAR IMAGERY CONTINUES TO SHOW PRECIP SHIELD BLOSSOMING
EARLY THIS MORNING AS LARGE SCALE FORCING INCREASES ACROSS THE
AREA. THIS FORCING COINCIDING WITH A THERMAL PROFILE SUPPORTIVE OF
A WINTRY MIX...HAS RESULTED IN WIDESPREAD SLEET AND FREEZING RAIN
BEING REPORTED. AT THE OFFICE HERE IN ROMEOVILLE...MORE SLEET
ACCUMULATION HAS BEEN NOTICED OVER THE LAST HOUR. THIS SLEET
ACCUMULATION AS WELL AS THE FURTHER BLOSSOMING OF THE PRECIP
SHIELD IS WHAT HAS PROMPTED THE ADVISORY. ALTHOUGH ANY SNOW/SLEET
ACCUMULATION WILL REMAIN RATHER MINOR AROUND AN INCH...ITS ONCE
AGAIN THE SLEET ACCUMULATION COINCIDING WITH LIGHT FREEZING RAIN
WHICH IS THE MAIN CONCERN...CONCERNS OF SLIPPERY CONDITIONS FOR
THE MORNING COMMUTE. STILL EXPECT FURTHER SNOW ACCUMULATION LATER
THIS MORNING INTO THE AFTERNOON...BUT WITH SNOW THE LIKELY PRECIP
TYPE.
RODRIGUEZ
//PREV DISCUSSION...
406 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH A
WINTRY MIX OF PRECIP ONGOING...AND THEN CONTINUING THROUGH THE
REMAINDER OF THE DAY WITH SNOW LIKELY ACROSS THE NORTHERN THIRD OF
THE CWA WHILE A RAIN/SNOW MIX FURTHER SOUTH TOWARDS THE I80
CORRIDOR...AND THEN ALL RAIN ACROSS THE SOUTHERN TIER OF COUNTIES.
LATEST RADAR IMAGERY IS DEPICTING AN AREA OF PRECIPITATION
SPREADING NORTH ACROSS PARTS OF NORTHEAST ILLINOIS AND NORTHWEST
INDIANA AS AN MID LEVEL WAVE TRACKS NORTHEAST ACROSS THE REGION.
LATEST REPORTS CONTINUE TO SUPPORT A WINTRY MIX THAT HAS BEEN
ANTICIPATED WITH SNOW OR SLEET FALLING ON THE NORTHERN FRINGE OF
THIS PRECIP SHIELD FROM STREATOR IN ILLINOIS EAST TO RENSSELAER IN
INDIANA...WHILE A RAIN SNOW MIX HAD BEEN REPORTED JUST SOUTH OF
THIS LINE. OVER THE NEXT COUPLE OF HOURS THIS TREND WILL LIKELY
CONTINUE AS THIS WINTRY MIX MOVES NORTH TOWARD THE CHICAGO METRO
AREA. ALTHOUGH WEAK...LATEST RAP ANALYSIS IS SHOWING SOME WAA
AIDING IN THIS DEVELOPMENT AND EXPECT THIS WEAK WAA TO FURTHER AID
THIS MORNING UNTIL MORE LARGE SCALE SUPPORT ARRIVES FROM THE WEST.
EXPECT SNOW OR SLEET WITH ONLY MINOR ACCUMULATIONS INITIALLY EARLY
THIS MORNING ALONG AND NORTH OF INTERSTATE 80...JUST SOUTH OF THE
INTERSTATE 80 CORRIDOR A RAIN SNOW MIX WILL BE LIKELY CONTINUE.
SURFACE TEMPS THIS MORNING HAVE BEEN SLOWLY FALLING WITH CURRENT
TEMPS AT OR JUST BELOW FREEZING ACROSS MUCH OF THE CWA. IN THOSE
AREAS WHERE LIGHT RAIN DOES OCCUR...THESE SURFACE TEMPERATURES
WILL SUPPORT THE POTENTIAL FOR BRIDGES AND ELEVATED ROADWAYS TO
ACCUMULATE A THIN LAYER OF ICING. ALTHOUGH THIS WINTRY MIX HAD
BEEN FALLING OVER THE LAST COUPLE OF HOURS...REPORTS HAD NOT
INDICATED ANY WIDESPREAD SLIPPERY CONDITIONS BUT WITH ROADS
REMAINING ONLY WET AT THAT TIME. WOULD SUSPECT THAT SLIPPERY
CONDITIONS ARE CURRENTLY DEVELOPING AND COULD POSSIBLY CONTINUE TO
DEVELOP OVER THE NEXT COUPLE OF HOURS. OF GREATEST CONCERN AT THIS
TIME FOR THESE SLIPPERY CONDITIONS WOULD BE THE I80 CORRIDOR WHERE
CURRENTLY THE STRONGEST RETURNS ON RADAR ARE LOCATED AS WELL AS
WITH SURFACE TEMPS JUST BELOW FREEZING. HAVE REISSUED AN SPS AT
THIS TIME FOR THOSE AREAS...WHILE NOT ISSUING ANY OTHER HEADLINES
AT THIS TIME. FORCING FOR THIS CURRENT PRECIP ACROSS THE CWA
SHOULD EXIT OVER THE NEXT COUPLE OF HOURS...WITH LATEST SHORT TERM
GUIDANCE SHOWING A DIMINISHING TREND WITHIN THE OVERALL EXTENT OF
THIS PRECIP. RESIDENCE TIME FOR ANY FURTHER LINGERING PRECIP IN
THESE AREAS SHOULD BE LIMITED THIS MORNING...AS THIS PRECIP AXIS
SLOWLY LIFTS NORTH. ALTHOUGH A DIMINISHING TREND HERE IN THE NEAR
TERM IS LIKELY...ONCE AGAIN STILL ANTICIPATE A NORTHWARD PUSH OF
THIS PRECIP.
LARGE SCALE FORCING FOR ASCENT WILL INCREASE THROUGH MID MORNING
AS THE CURRENT UPPER LEVEL TROUGH JUST TO THE WEST PUSHES EAST.
THIS IS ALREADY BEGINNING TO OCCUR OVER AREAS IN EASTERN IOWA
WHERE LIGHT RETURNS ARE BEGINNING TO SHOW UP ON RADAR. EXPECT
FURTHER DEVELOPMENT THROUGH MID TO LATE MORNING WITH A MIXED BAG
OF PRECIPITATION STILL LIKELY. ALTHOUGH...LATEST GUIDANCE IS
SHOWING THAT COLDER AIR WILL BE IN PLACE FURTHER SOUTH ACROSS THE
CWA THAN PREVIOUSLY ANTICIPATED WITH THE NUDGE OF WARMER AIR ALOFT
NOT AS PRONOUNCED FOR THIS MORNING OR MOST OF THE DAY...WITH
LATEST AMDAR SOUNDINGS SUPPORTED THESE THERMAL PROFILES. WITH THAT
IN MIND...HAVE SNOW OR SLEET POSSIBLE THROUGH MID MORNING FOR THE
NORTHERN HALF OF THE CWA ACROSS NORTH CENTRAL AND NORTHEAST
ILLINOIS WITH MORE LIQUID TYPE PRECIP EXPECTED FURTHER SOUTH.
SURFACE TEMPS WILL BE RISING THROUGH MID MORNING WITH ANY FURTHER
THREAT OF FREEZING RAIN IN THE CURRENT LOCATIONS BECOMING LESS
LIKELY. AS THIS UPPER LEVEL TROUGH SWINGS ACROSS THIS SNOW/SLEET
AND THEN SNOW THROUGH MID DAY AND EARLY AFTERNOON...DO THINK THERE
WILL BE SOME MINOR ACCUMULATIONS FOR AREAS ALONG AND NORTH OF THE
INTERSTATE 88 CORRIDOR INCLUDING THE WEST/NORTHWEST/NORTHERN
SUBURBS OF CHICAGO. ONE TO TWO INCHES WILL BE POSSIBLE NEAR THE
WISCONSIN BORDER WITH THREE INCHES AN OUTSIDE POSSIBILITY FOR
ISOLATED LOCATIONS...AND AROUND AN INCH FURTHER SOUTH. A TREND
TOWARDS MORE DRIZZLE WILL BE POSSIBLE BY MID AFTERNOON BUT AS THIS
OCCURS...MUCH COLDER AIR WILL BE SWEEPING THROUGH THE CWA. THIS
COULD HELP FOR FURTHER CRYSTALS TO DEVELOP AND HELP LIGHT SNOW TO
LINGER AROUND INTO THE AFTERNOON AND EARLY EVENING BUT WITH LITTLE
OR NO ADDITIONAL ACCUMULATION LIKELY. COLDER TEMPS STILL ON PAR
FOR THIS WEEK...STARTING OFF TONIGHT WITH LOW TO MID TEENS
POSSIBLE ACROSS MUCH OF THE CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* IFR CIGS LIFTING TO MVFR LATE AFTERNOON OR EARLY EVENING.
* MIXED PRECIPITATION/MISTY CONDITIONS WITH VSBY BOUNCING
AROUND...UNDER 2SM AT TIMES...AND 4-5SM AT TIMES.
* WINDS TURNING CLOCKWISE TO WESTERLY...THEN VERY QUICKLY RAMPING
UP WITH GUSTS TO 30 KTS LATE AFTERNOON/EARLY EVENING.
BMD
//DISCUSSION...UPDATED 18Z...
RADAR IMAGERY AND AREA OBSERVATIONS SHOW MIXED PRECIPITATION ACROSS
MUCH OF NORTHERN ILLINOIS...IN THE FORM OF LIGHT SNOW...RAIN...AND
DRIZZLE. A POCKET OF SLIGHTLY WARMER AIR ALOFT LIES BETWEEN ORD/MDW
EARLY THIS AFTERNOON WITH SN ON THE COLD SIDE (ORD) AND RAIN ON THE
WARM SIDE (MDW). EXPECT THIS LINE TO SHIFT EAST THROUGH THE EVENING
WITH SNOW BECOMING MORE PREVALENT FOR THE AREA TERMINALS. BASED ON
EXTRAPOLATION OF CURRENT RADAR TRENDS AND MOVEMENT OF UPPER LEVEL
TROUGH...EXPECT PRECIP TO TAPER FOR RFD AROUND 20Z...AND THE CHICAGO
TERMINALS AROUND 21Z. WITH THE LOSS OF DEEP MOISTURE BEHIND THE
UPPER WAVE...EXPECT PRECIP TO TAPER TO DRIZZLE WITH PERHAPS A FEW
FLURRIES MIXED IN AT TIMES. THIS COINCIDES WITH THE PASSAGE OF
A COLD FRONT WHICH WILL SWING WINDS TO WESTERLY. DRIER AIR AND
STEEPENING LOW LEVEL LAPSE RATES SHOULD LEAD TO SOME IMPROVEMENT IN
CIGS AND HELP DIMINISH THE MISTY CONDITIONS....BUT ALSO LOOKING AT
SOME POTENTIAL FOR A FEW WEAK INSTABILITY SNOW SHOWERS TO DEVELOP.
CONFIDENCE ON THE COVERAGE AND IMPACTS IS LOW AT THIS TIME...SO WILL
JUST MAINTAIN MENTION OF P6SM -SHSN THIS EVENING. THE OTHER CONCERN
FOR THE EARLY EVENING WILL BE WINDS SHARPLY INCREASING. AS
MENTIONED...INCREASING LOW LEVEL LAPSE RATES WILL TAP INTO STRONGER
WINDS ALOFT...COMBINED WITH AN AREA OF STRONG PRESSURE RISES TO PUSH
ACROSS THE AREA...EXPECT WINDS TO VERY QUICKLY INCREASE AND SHOULD
TOP OUT WITH GUSTS INTO THE LOW 30 KT RANGE AND LASTING THROUGH THE
OVERNIGHT HOURS.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM TO HIGH CONFIDENCE IN CIG TRENDS...MEDIUM CONFIDENCE IN
TIMING.
* MEDIUM CONFIDENCE IN PRECIP TYPE/TIMING.
* LOW TO MEDIUM CONFIDENCE IN VSBY TRENDS.
* MEDIUM TO HIGH CONFIDENCE IN WINDS.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH SUNDAY...MAINLY VFR...GUSTY WEST WINDS
TUESDAY NIGHT AND WEDNESDAY.
MDB
&&
.MARINE...
222 PM CDT
LOW PRESSURE SPINNING SLOWLY THROUGH THE NORTHERN GREAT LAKES
TONIGHT THROUGH MIDWEEK WILL PUSH AN UNNECESSARILY COLD COLD FRONT
ACROSS LAKE MICHIGAN THIS EVENING. WINDS WILL TURN SOUTHWEST AND
THEN WEST BEHIND THE FRONT AND INCREASE STEADILY THROUGH THE
EVENING.
HAVE ELECTED TO CONTINUE THE GALE WARNING FOR THE SOUTHERN
TWO THIRDS OF THE LAKE AND ALSO TO MOVE UP THE START TIME FOR THE
MIDDLE THIRD SO THAT IT MATCHES THE ORIGINAL START TIME FOR THE
SOUTHERN THIRD. STILL THINK THE NORTHERN THIRD WILL BE CLOSE ENOUGH
TO THE LOW ITSELF TO SEE WEAKER WINDS AND GUSTS...THOUGH LOCAL AREAS
COULD RECEIVE PERIODIC GALE FORCE GUSTS. UNUSUAL FOR MARCH...THERE
IS ALSO A POSSIBILITY OF FREEZING SPRAY WITH THE COLD AND GUSTY
WINDS BEHIND THE FRONT TONIGHT AND TOMORROW.
WINDS WILL TURN NORTHWEST BY WEDNESDAY AND DIMINISH SOMEWHAT...BUT
COLD AIR WILL REMAIN IN PLACE THROUGH THE WEEK.
LENNING
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...10 PM
MONDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1258 PM CDT MON MAR 18 2013
.DISCUSSION...
ISSUED 1057 AM CDT MON MAR 18 2013
WILL MAKE MINOR ADJUSTMENTS TO THE FORECAST TO KNOCK HIGH TEMPS
DOWN A FEW DEGREES AND CLEAN UP THE WORDING IN NORTHERN AREAS
REGARDING THE END OF THE FREEZING RAIN THREAT THIS MORNING.
ACCORDING TO THE RADAR A MAJORITY OF THE PRECIPITATION HAS MOVED
OUT OF THE FORECAST AREA AS OF 1045 AM...WITH SOME LIGHT
RAIN...MIXED IN SPOTS WITH LIGHT SNOW IN WEST CENTRAL IL. TEMPS
HAVE CLIMBED JUST ABOVE FREEZING TO BRING AN END TO THE FREEZING
RAIN THREAT...SO THE ADVISORY WAS ALLOWED TO EXPIRE. WILL KEEP THE
LOW CHANCES FOR LIGHT RAIN IN THE FORECAST FOR EARLY
AFTERNOON...MIXED WITH SNOW IN THE NORTHERN COUNTIES...ALONG WITH
CLOUDS AND GRADUALLY RISING TEMPS.
THE MAIN COLD FRONT...WHICH EXTENDED FROM A LOW IN NORTHERN MN
THROUGH CENTRAL IA TO NW MISSOURI IS STILL EXPECTED TO MOVE INTO
THE REGION THIS EVENING WITH A CLEARING SKY IN MOST AREAS. THE
CLOUDS MAY LINGER A BIT LONGER AROUND AND NORTH OF THE I-74
CORRIDOR EARLY TONIGHT.
&&
.AVIATION...
ISSUED 1258 PM CDT MON MAR 18 2013
MOST LOCATIONS IN CENTRAL AND EASTERN ILLINOIS WERE REPORTING
IFR...WITH A FEW LINGERING LIFR...CEILINGS. LOW PRESSURE IN
CENTRAL IND LIFTING TO THE NNE HAS RESULTED IN A BRISK WEST WIND
IN MOST LOCATIONS AS WELL. MOST OF THE PRECIPITATION HAS DEPARTED
THE REGION...WITH THE EXCEPTION OF LINGERING LIGHT RAIN SHOWERS
ALONG AND NORTH OF I-74. WILL KEEP THESE GOING IN THE TAFS FOR
KPIA AND KBMI EARLY THIS AFTERNOON.
THE MAIN CONCERN FROM MID-AFTERNOON AND BEYOND IS THE SKY
CONDITION AND WHEN ANY CLEARING MAY APPROACH. THE LATEST IR
SATELLITE LOOP AND SURFACE OBS INDICATED THAT CLEARING IN WESTERN
MO WAS MOVING ESE AROUND 30 MPH OR SO. THIS WOULD EXTRAPOLATE INTO
CENTRAL IL CLOSE TO 00Z...WHICH MATCHES FAIRLY WELL WITH THE
LATEST HRRR MODEL.
TAF SITES FROM KPIA-KBMI-KCMI MAY NOT CLEAR AS QUICK BECAUSE THEY
COULD END UP BEING ON THE SOUTHERN EDGE OF THE LOW CLOUD SHIELD
WITH THE SHORTWAVE TROUGH SWINGING THROUGH THE WESTERN GREAT LAKES
REGION. FOR NOW WILL KEEP AT LEAST MVFR CONDITIONS IN PLACE FOR
THESE AREAS THROUGH THE EVENING (TIL 05-06Z) AND GRADUALLY CLEAR
THE SKY OVERNIGHT.
AN INCREASING PRESSURE GRADIENT AHEAD OF THE CLEARING/SURFACE
BOUNDARY IN WESTERN MO WILL ALSO RESULT IN GUSTY WINDS FROM THE
WEST THIS AFTERNOON INTO EARLY THIS EVENING.
MILLER
&&
.PREV DISCUSSION...
ISSUED 242 AM CDT MON MAR 18 2013
SHORT TERM...TODAY THROUGH WEDNESDAY
LOW PRESSURE CURRENTLY OVER WESTERN KENTUCKY WILL LIFT
NORTHEASTWARD INTO INDIANA THIS MORNING...IN RESPONSE TO AN
APPROACHING SHORT-WAVE TROUGH. MOST OF THE PRECIPITATION
ASSOCIATED WITH THIS FEATURE WILL SHIFT FURTHER EAST INTO THE OHIO
RIVER VALLEY AFTER 12Z...HOWEVER SCATTERED VERY LIGHT SHOWERS WILL
PERSIST ACROSS MUCH OF CENTRAL ILLINOIS THROUGH MIDDAY. FORECAST
SOUNDINGS SUGGEST A COMPLETE LOSS OF ICE CRYSTALS...SO ANY
LINGERING PRECIP WILL BE IN LIQUID FORM. WITH SURFACE TEMPS
HOVERING AT OR JUST BELOW THE FREEZING MARK...COULD SEE SOME VERY
LIGHT FREEZING RAIN/DRIZZLE ALONG AND NORTH OF A CANTON TO
BLOOMINGTON-NORMAL LINE FOR A FEW HOURS THIS MORNING. SINCE PRECIP
IS EXPECTED TO BE VERY LIGHT AND TEMPS BORDERLINE...AM NOT
ANTICIPATING ANY PROBLEMS WITH ICING. ONCE LOW LIFTS FURTHER
NORTHEAST...PRECIP WILL END FROM WEST TO EAST ACROSS THE AREA BY
EARLY AFTERNOON. HIGH TEMPERATURES WILL MAINLY BE IN THE
40S...WITH READINGS AROUND 50 DEGREES ACROSS THE FAR SE KILX CWA.
ONCE UPPER SHORT-WAVE PASSES TO THE EAST...SYNOPTIC SUBSIDENCE IN
ITS WAKE WILL LEAD TO CLEARING SKIES TONIGHT. BRISK WESTERLY WINDS
WILL TRANSPORT COLDER AIR INTO THE REGION AS WELL...ALLOWING
OVERNIGHT LOWS TO DROP INTO THE 20S. MOSTLY SUNNY AND COLD
CONDITIONS WILL BE THE RULE TUESDAY MORNING...WITH TEMPS ONLY
RECOVERING TO THE UPPER 30S AND LOWER 40S BY AFTERNOON. 00Z MAR 18
MODELS CONTINUE TO ADVERTISE A FAST-MOVING WAVE DIVING
SOUTHEASTWARD OUT OF THE NORTHERN ROCKIES ON TUESDAY. WHILE MODEL
CONSENSUS GENERALLY KEEPS THIS FEATURE JUST OFF TO THE W/SW OF
CENTRAL ILLINOIS...THINK IT WILL PASS CLOSE ENOUGH TO BRING
INCREASING CLOUDS AND PERHAPS SOME VERY LIGHT PRECIP ACROSS THE
FAR S/SW CWA TUESDAY AFTERNOON AND NIGHT. HAVE INCLUDED A CHANCE
FOR SPRINKLES AROUND JACKSONVILLE LATE TUESDAY AFTERNOON...THEN A
CHANCE FOR SNOW FLURRIES ALONG AND SOUTH OF A JACKSONVILLE...TO
EFFINGHAM...TO ROBINSON LINE TUESDAY NIGHT. ANY MEASURABLE PRECIP
WILL LIKELY REMAIN FURTHER SOUTHWEST ACROSS THE OZARKS INTO THE
TENNESSEE RIVER VALLEY.
DEEP UPPER LOW CENTERED OVER THE GREAT LAKES WILL DIG SOUTHWARD
ON WEDNESDAY...PUSHING A CHUNK OF VERY COLD AIR INTO THE MIDWEST
BEHIND TUESDAY NIGHTS DEPARTING SHORT-WAVE. 850MB TEMPS ARE PROGGED
TO DROP INTO THE -13 TO -16C RANGE...SUPPORTING HIGHS ONLY IN THE
30S. SOME LOCATIONS ACROSS THE NORTHERN CWA MAY REMAIN IN THE
UPPER 20S...THANKS TO STRONG CAA. WITH CLEAR SKIES EXPECTED...THE
COLDEST NIGHT OF THE FORECAST PACKAGE WILL BE WEDNESDAY
NIGHT...WHEN LOWS DROP INTO THE TEENS ACROSS THE BOARD.
LONG TERM...THURSDAY THROUGH SUNDAY
CHILLY EARLY SPRING WEATHER WILL PERSIST THROUGHOUT THE ENTIRE
EXTENDED...THANKS TO A PERSISTENT NORTHWESTERLY FLOW EXPECTED TO
CONTINUE INTO NEXT WEEK. WHILE UPPER HEIGHTS WILL RISE
SOMEWHAT...TEMPS WILL ONLY MODERATE BACK INTO THE 40S FRIDAY
THROUGH SUNDAY. CONSIDERABLE MODEL DISCREPANCY EXISTS CONCERNING
POTENTIAL FOR PRECIP LATE IN THE WEEKEND...WITH THE GFS SHOWING A
CLOSED 500MB LOW TRACKING INTO THE OHIO RIVER VALLEY BY SUNDAY
EVENING. THIS SOLUTION COULD POSSIBLY BRING SNOW TO CENTRAL
ILLINOIS SATURDAY NIGHT INTO SUNDAY. HOWEVER...THE GFS IS THE LONE
OUTLIER SHOWING THIS HIGHLY AMPLIFIED SOLUTION...WITH BOTH THE GEM
AND ECMWF INDICATING WEAKER UPPER SYSTEMS MUCH FURTHER SOUTH
ACROSS THE GULF COAST. HAVE THEREFORE OPTED TO REJECT THE GFS IN
FAVOR OF THE COOL/DRY MODEL CONSENSUS THROUGH THE WEEKEND.
BARNES
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1251 PM CDT MON MAR 18 2013
.DISCUSSION...
1055 AM CDT
CONTINUING TO MONITOR OBSERVATIONAL AND SHORT TERM GUIDANCE AS
LATE SEASON LIGHT WINTRY PRECIP EVENT CONTINUES. WE HAVE HOWEVER
LET THE ADVISORY END AT 11 AM AS INITIALLY PLANNED...DUE MAINLY
TO THE THREAT OF APPRECIABLE FREEZING PRECIPITATION HAVING ENDED.
ONE SHORT WAVE IMPULSE IS CURRENTLY PROGRESSING NORTHEAST OVER
LAKE MI AND WAS RESPONSIBLE FOR OUR EARLY MORNING LIGHT
ACCUMULATIONS. THE PRIMARY UPPER WAVE IS APPROACHING QUICKLY ACROSS
IA AND IS VERY WELL-DEFINED ON THE WATER VAPOR CHANNEL. WEAK WARM
AND MOIST ADVECTION ALOFT CONTINUES ACROSS THE SOUTHERN AND
EASTERN AREA...BUT A GOOD PART OF THE MOISTURE TRANSPORT WAS AND
CONTINUES TO BE ROBBED BY OHIO VALLEY/LOWER MISSISSIPPI VALLEY
CONVECTION. STILL GETTING SPOTTER REPORTS AND PUBLIC REPORTS
THROUGH THE NSSL MPING APPLICATION OF LIGHT FREEZING PRECIPITATION
ACROSS CHICAGO...AND RECENT AMDAR SOUNDINGS DO SUPPORT A LIGHT MIX.
WITH CONTINUED LIGHT ARCED RADAR ECHOES OF AN ISENTROPIC ASCENT
NATURE SHOWING UP ACROSS CHICAGO INTO NORTHWEST INDIANA...WILL
CONTINUE THE MENTION FOR LIGHT FREEZING PRECIP/SLEET IN THE
FORECAST FOR THOSE AREAS INTO EARLY AFTERNOON. WITH THE LIGHT
RATES AND TEMPERATURES HAVING INCHED UP TO THE 30 TO 32
MARK...EXPECTING ANY ICE ACCUMULATION TO BE LIGHT.
AS THE UPPER WAVE PROGRESSES IN...ELEVATED STEEP LAPSE RATES IN
TANDEM WITH DEEPER MOISTURE SUPPORT THE POTENTIAL FOR MODEST
SNOW/SNOW SHOWERS MOVING ACROSS NORTHERN IL...ESPECIALLY ALONG AND
NORTH OF I-88. THIS POTENTIAL IS VERIFIED WITH NUMEROUS EASTERN IA
LOCATIONS HAVING REPORTED VISIBILITY UNDER 1SM. HIGH RES
REFLECTIVITY PRODUCING MODELS SHOW CONTINUED ENHANCEMENT AS THIS
AREA PROGRESSES EAST ACROSS NORTHERN IL THROUGH EARLY TO MID
AFTERNOON WHICH MAKES SENSE WITH THE AFOREMENTIONED FORCING.
SCATTERED HEAVY RATES ARE POSSIBLE AT TIMES...ESPECIALLY IN THE WI
BORDER COUNTIES. DO NOT WANT TO DOWNPLAY TEMPORARY IMPACTS TO
TRAVEL ESPECIALLY WITH BURSTS OF HEAVIER RATES...BUT WILL MENTION
THAT IN AN SPS AS OPPOSED TO EXTENDING THE ADVISORY AS ADDITIONAL
SNOWFALL ACCUMULATIONS LOOK TO BE ON THE ORDER OF ONE TO MAYBE TWO
INCHES AT MOST AND THE FREEZING PRECIP THREAT ENDING FROM WEST TO
EAST.
MTF
//PREV DISCUSSION...
529 AM CDT
A WINTER ADVISORY HAS BEEN ISSUED FOR A PORTION OF NORTHERN
ILLINOIS AND NORTHWEST INDIANA THROUGH 11 AM...WITH SLEET AND
FREEZING RAIN THE MAIN CONCERNS.
LATEST RADAR IMAGERY CONTINUES TO SHOW PRECIP SHIELD BLOSSOMING
EARLY THIS MORNING AS LARGE SCALE FORCING INCREASES ACROSS THE
AREA. THIS FORCING COINCIDING WITH A THERMAL PROFILE SUPPORTIVE OF
A WINTRY MIX...HAS RESULTED IN WIDESPREAD SLEET AND FREEZING RAIN
BEING REPORTED. AT THE OFFICE HERE IN ROMEOVILLE...MORE SLEET
ACCUMULATION HAS BEEN NOTICED OVER THE LAST HOUR. THIS SLEET
ACCUMULATION AS WELL AS THE FURTHER BLOSSOMING OF THE PRECIP
SHIELD IS WHAT HAS PROMPTED THE ADVISORY. ALTHOUGH ANY SNOW/SLEET
ACCUMULATION WILL REMAIN RATHER MINOR AROUND AN INCH...ITS ONCE
AGAIN THE SLEET ACCUMULATION COINCIDING WITH LIGHT FREEZING RAIN
WHICH IS THE MAIN CONCERN...CONCERNS OF SLIPPERY CONDITIONS FOR
THE MORNING COMMUTE. STILL EXPECT FURTHER SNOW ACCUMULATION LATER
THIS MORNING INTO THE AFTERNOON...BUT WITH SNOW THE LIKELY PRECIP
TYPE.
RODRIGUEZ
//PREV DISCUSSION...
406 AM CDT
MAIN FORECAST CHALLENGES/CONCERNS ARE IN THE NEAR TERM WITH A
WINTRY MIX OF PRECIP ONGOING...AND THEN CONTINUING THROUGH THE
REMAINDER OF THE DAY WITH SNOW LIKELY ACROSS THE NORTHERN THIRD OF
THE CWA WHILE A RAIN/SNOW MIX FURTHER SOUTH TOWARDS THE I80
CORRIDOR...AND THEN ALL RAIN ACROSS THE SOUTHERN TIER OF COUNTIES.
LATEST RADAR IMAGERY IS DEPICTING AN AREA OF PRECIPITATION
SPREADING NORTH ACROSS PARTS OF NORTHEAST ILLINOIS AND NORTHWEST
INDIANA AS AN MID LEVEL WAVE TRACKS NORTHEAST ACROSS THE REGION.
LATEST REPORTS CONTINUE TO SUPPORT A WINTRY MIX THAT HAS BEEN
ANTICIPATED WITH SNOW OR SLEET FALLING ON THE NORTHERN FRINGE OF
THIS PRECIP SHIELD FROM STREATOR IN ILLINOIS EAST TO RENSSELAER IN
INDIANA...WHILE A RAIN SNOW MIX HAD BEEN REPORTED JUST SOUTH OF
THIS LINE. OVER THE NEXT COUPLE OF HOURS THIS TREND WILL LIKELY
CONTINUE AS THIS WINTRY MIX MOVES NORTH TOWARD THE CHICAGO METRO
AREA. ALTHOUGH WEAK...LATEST RAP ANALYSIS IS SHOWING SOME WAA
AIDING IN THIS DEVELOPMENT AND EXPECT THIS WEAK WAA TO FURTHER AID
THIS MORNING UNTIL MORE LARGE SCALE SUPPORT ARRIVES FROM THE WEST.
EXPECT SNOW OR SLEET WITH ONLY MINOR ACCUMULATIONS INITIALLY EARLY
THIS MORNING ALONG AND NORTH OF INTERSTATE 80...JUST SOUTH OF THE
INTERSTATE 80 CORRIDOR A RAIN SNOW MIX WILL BE LIKELY CONTINUE.
SURFACE TEMPS THIS MORNING HAVE BEEN SLOWLY FALLING WITH CURRENT
TEMPS AT OR JUST BELOW FREEZING ACROSS MUCH OF THE CWA. IN THOSE
AREAS WHERE LIGHT RAIN DOES OCCUR...THESE SURFACE TEMPERATURES
WILL SUPPORT THE POTENTIAL FOR BRIDGES AND ELEVATED ROADWAYS TO
ACCUMULATE A THIN LAYER OF ICING. ALTHOUGH THIS WINTRY MIX HAD
BEEN FALLING OVER THE LAST COUPLE OF HOURS...REPORTS HAD NOT
INDICATED ANY WIDESPREAD SLIPPERY CONDITIONS BUT WITH ROADS
REMAINING ONLY WET AT THAT TIME. WOULD SUSPECT THAT SLIPPERY
CONDITIONS ARE CURRENTLY DEVELOPING AND COULD POSSIBLY CONTINUE TO
DEVELOP OVER THE NEXT COUPLE OF HOURS. OF GREATEST CONCERN AT THIS
TIME FOR THESE SLIPPERY CONDITIONS WOULD BE THE I80 CORRIDOR WHERE
CURRENTLY THE STRONGEST RETURNS ON RADAR ARE LOCATED AS WELL AS
WITH SURFACE TEMPS JUST BELOW FREEZING. HAVE REISSUED AN SPS AT
THIS TIME FOR THOSE AREAS...WHILE NOT ISSUING ANY OTHER HEADLINES
AT THIS TIME. FORCING FOR THIS CURRENT PRECIP ACROSS THE CWA
SHOULD EXIT OVER THE NEXT COUPLE OF HOURS...WITH LATEST SHORT TERM
GUIDANCE SHOWING A DIMINISHING TREND WITHIN THE OVERALL EXTENT OF
THIS PRECIP. RESIDENCE TIME FOR ANY FURTHER LINGERING PRECIP IN
THESE AREAS SHOULD BE LIMITED THIS MORNING...AS THIS PRECIP AXIS
SLOWLY LIFTS NORTH. ALTHOUGH A DIMINISHING TREND HERE IN THE NEAR
TERM IS LIKELY...ONCE AGAIN STILL ANTICIPATE A NORTHWARD PUSH OF
THIS PRECIP.
LARGE SCALE FORCING FOR ASCENT WILL INCREASE THROUGH MID MORNING
AS THE CURRENT UPPER LEVEL TROUGH JUST TO THE WEST PUSHES EAST.
THIS IS ALREADY BEGINNING TO OCCUR OVER AREAS IN EASTERN IOWA
WHERE LIGHT RETURNS ARE BEGINNING TO SHOW UP ON RADAR. EXPECT
FURTHER DEVELOPMENT THROUGH MID TO LATE MORNING WITH A MIXED BAG
OF PRECIPITATION STILL LIKELY. ALTHOUGH...LATEST GUIDANCE IS
SHOWING THAT COLDER AIR WILL BE IN PLACE FURTHER SOUTH ACROSS THE
CWA THAN PREVIOUSLY ANTICIPATED WITH THE NUDGE OF WARMER AIR ALOFT
NOT AS PRONOUNCED FOR THIS MORNING OR MOST OF THE DAY...WITH
LATEST AMDAR SOUNDINGS SUPPORTED THESE THERMAL PROFILES. WITH THAT
IN MIND...HAVE SNOW OR SLEET POSSIBLE THROUGH MID MORNING FOR THE
NORTHERN HALF OF THE CWA ACROSS NORTH CENTRAL AND NORTHEAST
ILLINOIS WITH MORE LIQUID TYPE PRECIP EXPECTED FURTHER SOUTH.
SURFACE TEMPS WILL BE RISING THROUGH MID MORNING WITH ANY FURTHER
THREAT OF FREEZING RAIN IN THE CURRENT LOCATIONS BECOMING LESS
LIKELY. AS THIS UPPER LEVEL TROUGH SWINGS ACROSS THIS SNOW/SLEET
AND THEN SNOW THROUGH MID DAY AND EARLY AFTERNOON...DO THINK THERE
WILL BE SOME MINOR ACCUMULATIONS FOR AREAS ALONG AND NORTH OF THE
INTERSTATE 88 CORRIDOR INCLUDING THE WEST/NORTHWEST/NORTHERN
SUBURBS OF CHICAGO. ONE TO TWO INCHES WILL BE POSSIBLE NEAR THE
WISCONSIN BORDER WITH THREE INCHES AN OUTSIDE POSSIBILITY FOR
ISOLATED LOCATIONS...AND AROUND AN INCH FURTHER SOUTH. A TREND
TOWARDS MORE DRIZZLE WILL BE POSSIBLE BY MID AFTERNOON BUT AS THIS
OCCURS...MUCH COLDER AIR WILL BE SWEEPING THROUGH THE CWA. THIS
COULD HELP FOR FURTHER CRYSTALS TO DEVELOP AND HELP LIGHT SNOW TO
LINGER AROUND INTO THE AFTERNOON AND EARLY EVENING BUT WITH LITTLE
OR NO ADDITIONAL ACCUMULATION LIKELY. COLDER TEMPS STILL ON PAR
FOR THIS WEEK...STARTING OFF TONIGHT WITH LOW TO MID TEENS
POSSIBLE ACROSS MUCH OF THE CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* IFR CIGS LIFTING TO MVFR LATE AFTERNOON OR EARLY EVENING.
* MIXED PRECIPITATION/MISTY CONDITIONS WITH VSBY BOUNCING
AROUND...UNDER 2SM AT TIMES...AND 4-5SM AT TIMES.
* WINDS TURNING CLOCKWISE TO WESTERLY...THEN VERY QUICKLY RAMPING
UP WITH GUSTS TO 30 KTS LATE AFTERNOON/EARLY EVENING.
BMD
//DISCUSSION...UPDATED 18Z...
RADAR IMAGERY AND AREA OBSERVATIONS SHOW MIXED PRECIPITATION ACROSS
MUCH OF NORTHERN ILLINOIS...IN THE FORM OF LIGHT SNOW...RAIN...AND
DRIZZLE. A POCKET OF SLIGHTLY WARMER AIR ALOFT LIES BETWEEN ORD/MDW
EARLY THIS AFTERNOON WITH SN ON THE COLD SIDE (ORD) AND RAIN ON THE
WARM SIDE (MDW). EXPECT THIS LINE TO SHIFT EAST THROUGH THE EVENING
WITH SNOW BECOMING MORE PREVALENT FOR THE AREA TERMINALS. BASED ON
EXTRAPOLATION OF CURRENT RADAR TRENDS AND MOVEMENT OF UPPER LEVEL
TROUGH...EXPECT PRECIP TO TAPER FOR RFD AROUND 20Z...AND THE CHICAGO
TERMINALS AROUND 21Z. WITH THE LOSS OF DEEP MOISTURE BEHIND THE
UPPER WAVE...EXPECT PRECIP TO TAPER TO DRIZZLE WITH PERHAPS A FEW
FLURRIES MIXED IN AT TIMES. THIS COINCIDES WITH THE PASSAGE OF
A COLD FRONT WHICH WILL SWING WINDS TO WESTERLY. DRIER AIR AND
STEEPENING LOW LEVEL LAPSE RATES SHOULD LEAD TO SOME IMPROVEMENT IN
CIGS AND HELP DIMINISH THE MISTY CONDITIONS....BUT ALSO LOOKING AT
SOME POTENTIAL FOR A FEW WEAK INSTABILITY SNOW SHOWERS TO DEVELOP.
CONFIDENCE ON THE COVERAGE AND IMPACTS IS LOW AT THIS TIME...SO WILL
JUST MAINTAIN MENTION OF P6SM -SHSN THIS EVENING. THE OTHER CONCERN
FOR THE EARLY EVENING WILL BE WINDS SHARPLY INCREASING. AS
MENTIONED...INCREASING LOW LEVEL LAPSE RATES WILL TAP INTO STRONGER
WINDS ALOFT...COMBINED WITH AN AREA OF STRONG PRESSURE RISES TO PUSH
ACROSS THE AREA...EXPECT WINDS TO VERY QUICKLY INCREASE AND SHOULD
TOP OUT WITH GUSTS INTO THE LOW 30 KT RANGE AND LASTING THROUGH THE
OVERNIGHT HOURS.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM TO HIGH CONFIDENCE IN CIG TRENDS...MEDIUM CONFIDENCE IN
TIMING.
* MEDIUM CONFIDENCE IN PRECIP TYPE/TIMING.
* LOW TO MEDIUM CONFIDENCE IN VSBY TRENDS.
* MEDIUM TO HIGH CONFIDENCE IN WINDS.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH SUNDAY...MAINLY VFR...GUSTY WEST WINDS
TUESDAY NIGHT AND WEDNESDAY.
MDB
&&
.MARINE...
323 AM CDT
LOW PRESSURE CONTINUES TO MOVE EAST ACROSS THE EASTERN DAKOTAS AND
WILL REACH EASTERN LAKE SUPERIOR TUESDAY MORNING. ANOTHER LOW IS
ALSO MOVING UP THE OHIO RIVER VALLEY AND WILL MERGE WITH THE MAIN
LOW TUESDAY. EAST TO SOUTHEAST WINDS CONTINUE ACROSS LAKE MICHIGAN
THIS MORNING WITH THE STRONGEST SPEEDS ACROSS THE CENTRAL SECTION OF
THE LAKE. THE PRESSURE GRADIENT WILL WEAKEN THROUGH THE MORNING
ALLOWING SPEEDS TO EASE UP WITH WINDS THEN SHIFTING TO THE WEST AND
SOUTHWEST THROUGH THE AFTERNOON. THE WEAKENING WINDS AND SHIFT IN
DIRECTION SHOULD HELP TO KNOCK WAVES DOWN SO WILL PLAN ON LETTING
THE SMALL CRAFT ADVISORY FOR THE ILLINOIS NEARSHORE WATERS EXPIRE AT
18Z. WEST WINDS WILL RAMP UP TO 35-40 KT GALES ACROSS THE SOUTHERN
TWO-THIRDS OF THE LAKE THIS EVENING WITH THE FAR NORTHERN SECTION
LIKELY BEING HELD TO AROUND 30 KT THANKS TO THE NEARBY PASSAGE OF
THE SURFACE LOW TONIGHT. HAVE UPGRADED THE GALE WATCH TO A GALE
WARNING FOR THE OPEN WATERS. ISSUED A GALE WATCH FOR THE ILLINOIS
NEARSHORE WATERS AS WELL AS THE INDIANA WATERS FROM CALUMET HARBOR
TO GARY...WITH SOME UNCERTAINTY ON WHETHER GALE FORCE WILL BE ABLE
TO BE REACHED GIVEN THE OFFSHORE WIND COMPONENT. HOWEVER...DID
UPGRADE AREAS FROM GARY EAST TO A GALE WARNING GIVEN THEIR BETTER
ONSHORE EXPOSURE. OTHERWISE...TEMPERATURES WILL FALL AS MUCH COLDER
AIR BUILDS IN WHICH WILL SET THE STAGE FOR FREEZING SPRAY. THE LOW
WILL BE SLOW TO DEPART TO THE EAST WHILE HIGH PRESSURE SPREADS INTO
THE NORTHERN PLAINS INTO TUESDAY NIGHT. THIS WILL KEEP WINDS STRONG
INTO TUESDAY EVENING BUT SPEEDS LOOK TO FALL JUST BELOW GALE FORCE
TUESDAY EVENING OR TUESDAY NIGHT...BUT SOME GALE FORCE GUSTS MAY
CONTINUE EVEN THROUGH WEDNESDAY. WILL KEEP 30 KT IN THE FORECAST FOR
THIS TIME FRAME FOR NOW THOUGH. THE PRESSURE GRADIENT WILL GRADUALLY
WEAKEN THROUGH THURSDAY AS THE LOW FILLS TO THE EAST AND THE HIGH
BROADENS TO THE WEST. NORTHEASTERLY LOW LEVEL FLOW LOOKS TO SET UP
NEXT WEEKEND WITH THE MAIN TRACK OF LOW PRESSURE SYSTEMS POSITIONED
SOUTH OF THE LAKE.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 1 PM MONDAY.
GALE WARNING...LMZ080-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ872-LMZ874-LMZ876-
LMZ878...10 PM MONDAY TO 9 PM TUESDAY.
GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870...3 AM
TUESDAY TO 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1106 AM CDT MON MAR 18 2013
.DISCUSSION...
COLD FRONT MAKING STEADY PROGRESS ACROSS THE REGION THIS
MORNING...AND IS NOW ROUGHLY ALONG A LINE FROM WACO TX...TO
GILMER...TO CAMDEN AR. CONVECTION ALONG THE FRONT HAS BEEN DECENT
ACROSS SE OK/SW AR...BUT HAD STRUGGLED FARTHER S. KSHV 12Z
SOUNDING SHOWS A SUBSTANTIAL CAP...AND THIS IS LIKELY THE REGION
THAT WE HAVEN`T SEEN MORE THUNDERSTORM ACTIVITY. FOR THE
UPDATE...HAVE MADE A FEW ADJUSTMENTS TO POPS/WX BASED ON RADAR
TRENDS. HAVE UPDATED THE FRONTAL POSITION VIA HOURLY TEMPS/DEW
POINTS...AND HAVE ACCORDINGLY LOWERED MAX TEMPS N OF THE FRONT
AND RAISED THEM S OF THE FRONT BASED ON CURRENT OBS AND CLOUD
COVER. /12/
&&
.AVIATION...
COLD FRONT AS OF 15Z WAS LOCATED NEAR A PBF...TXK...CPT LINE AS
AFTER HAVING STALLED OUT LAST NIGHT...WAS FINALLY BEGINNING TO MARCH
SOUTH AND EAST. CONVECTION HAS TRIED TO GET GOING ALONG THE BOUNDARY
NEAR THE I-30 CORRIDOR OF NE TX INTO SW AR BUT LOOKS VERY
DISORGANIZED ATTM. PLENTY OF INSTABILITY IN PRESENT TO THE SOUTH OF
THE BOUNDARY BUT A STRONG CAPPING INVERSION WILL LIKELY KEEP THE
STORMS ELEVATED...AT LEAST FOR THE REMAINDER OF THE MORNING WITH
SMALL HAIL THE GREATEST THREAT.
CEILINGS FOR THE MOST PART THIS MORNING HAVE AND REMAIN MVFR
CATEGORY RANGING NEAR 1KFT TO NEAR 2KFT. CEILINGS WILL LIKELY REMAIN
MVFR FOR A FEW MORE HOURS AHEAD OF THE FRONTAL BOUNDARY AND MAY THIN
AND/OR LIFT JUST ABOVE 3KFT DURING THE AFTERNOON. CURRENTLY SEEING
IFR CEILINGS BELOW 1KFT IN THE POST FRONTAL AIRMASS ACROSS NC TEXAS
ATTM AND THUS WILL NEED TO WATCH FOR THESE CONDITIONS FILLING IN
BEHIND THE FRONT THIS AFTERNOON. ADDITIONAL CONVECTION WILL LIKELY
ONLY EFFECT THE SHV/TXK/ELD/MLU TERMINALS UNLESS SOMETHING CHANGES
CLOSER TO TAF TIME...WILL ONLY MAKE MENTION IN THESE TERMINALS NEW
FCST PACKAGE AT 18Z. /13/
&&
.PREV DISCUSSION... /ISSUED 549 AM CDT MON MAR 18 2013/
DISCUSSION...
AS ALWAYS THERE IS ROOM FOR IMPROVEMENTS WHICH IS WHY WE DO LIKE
TO UPDATE THE FORECAST...BUT NOW THIS WHOLE WEEK IS A REAL HEAD
SCRATCHER INSIDE OF A MODEL RUN. EVEN THE DAY AHEAD IS GETTING OFF
TRACK WITH SOME OF THE AVAILABLE GUIDANCE. OBSERVATION IS ALWAYS A
GOOD STARTING PLACE WITH THE I-30 CORRIDOR RANGING IN THE 50S AND
MID TO UPPER 60S ELSEWHERE. THIS STATIONARY FRONT STRETCHES JUST
SOUTH OF I-30 IN NE TX AND THEN LIFTS NORTH OF I-30 AT TXK AND
THEN BACK TO THE SOUTH OF I-30 INTO LITTLE ROCK. WE ARE NOT GOING
TO SEE MUCH MOVEMENT HERE OVER THE NEXT FEW HOURS...BUT NAM
GUIDANCE PICKS UP SFC WINDS AS THE FRONT STARTS BACK TO THE SOUTH
OVER NE TX LATE THIS MORNING INTO THE EARLY AFTERNOON...GETTING
INTO SHV BY 21Z AND THE REMAINDER OF THE CWA NEARLY BY 00Z...MAYBE
A BIT FAST ON THAT LAST SEGMENT.
OTHERWISE...THE MID LEVEL CAP HAS BEEN TOO MUCH FOR ANYTHING OTHER
THAN A FEW SHALLOW LIGHT SHOWERS. THE WATER VAPOR SHOWS A SHORT
WAVE KNOCKING ON OUR DOOR OVER OK/N TX AND NNE SFC GUSTS ARE
SPREADING ACROSS THE RED RIVER THERE IN IT/S WAKE. THE SFC
GRADIENT IS WEAK...BUT THE SHORT WAVE IS GOING TO HELP THE SFC
BOUNDARY GET MOVING AS NAM GUIDANCE SUGGESTS. THE DISTURBANCE
SHOULD HELP TO WEAKEN THE CAP AND THE EXPECTATION IS FOR SCATTERED
DEVELOPMENT BOTH PRE AND POST FRONTAL...LATE THIS MORNING AND
DURING MUCH OF THE AFTERNOON. WE HAVE GONE FROM A SLIGHT RISK TO
GENERAL FOR THE DAY WITH THE MORNING TIME FRAME GENERALLY A TOUGH
TIME TO GET ANYTHING GOING ANYWAY. OUR RADAR HAS BEEN MOSTLY QUIET
AS THE LOW LEVEL JET HAS JUST BEEN STRONGER RIGHT BENEATH THE CAP
AND NOT STRONG ENOUGH IN THE LOWEST LEVELS. OVERNIGHT...WE HAVE NOT
SEEN ENOUGH ENERGY RIDING OVER THE STATIONARY FRONT AND WE APPEAR
TO NEED DAYTIME HEATING TO MAKE A LAST DITCH EFFORT AT DEVELOPMENT
OVER THE CWA LATER THIS MORNING. TIMING IS EVERYTHING IN THIS
BUSINESS AND HURRY UP AND WAIT IS ALL TOO OFTEN THE REALITY. AT
ANY RATE...THE SFC HIGH PRESSURE GRADIENT IS NOT VERY STRONG EVEN
WELL BEHIND THE FRONT WITH THE GFS AT 12Z LOOKING AT 1015 MB OVER
SW KN WITH OBS SHOWING 1012 STILL IN NW KN. THE NAM IS EVEN
STRONGER WITH 1017MB AT 12Z. THE RAP INITIALIZES BEST RIGHT NOW
AND DOES END UP LOOKING MUCH THE NAM AND GFS BY LATER THIS
AFTERNOON AS FAR AS SFC PRESSURES INCREASING IN OUR CWA.
THE MID WEEK PERIOD IS COMPARABLE TO WHAT WE HAVE HAD OUT...BUT
HAS TRENDED DRIER LONGER THROUGH MIDWEEK WITH THE NEXT EVENT
LIKELY TO BE OVERRUNNING AND A MUCH BETTER RAIN MAKER FOR THE AREA
AS A WHOLE LATE IN THE WORK WEEK. THE ECMWF IS PREFERRED AND TAKES
OVER WHERE GFS LEAVES OFF DURING MID WEEK. THE MEX GUIDANCE HAD
60S...BUT HAS GONE 180 OUT AND IS NOW LOOKING AT 80S FOR TEMPS
INTO SATURDAY WITH EURO MORE OF A STATUS QUO APPROACH AND WHILE
THERE MAY BE SOME CHANGES TO THE LONGER TERM AS WELL...WE WILL
HOLD OFF ANOTHER MODEL RUN OR TWO TO SEE IF WE CAN GET SOME KIND
OF AGREEMENT. /24/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 76 47 70 48 71 / 30 10 10 30 20
MLU 79 47 68 45 69 / 40 10 10 20 20
DEQ 61 36 67 38 68 / 20 10 10 20 10
TXK 64 43 67 43 68 / 30 10 10 20 10
ELD 72 41 67 41 69 / 40 10 10 20 10
TYR 72 45 69 50 70 / 20 10 10 30 10
GGG 75 46 68 47 71 / 20 10 10 30 10
LFK 82 49 74 51 74 / 10 10 10 30 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
12/13
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
430 PM EDT MON MAR 18 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 429 PM EDT MON MAR 18 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW NEG-TILT TROUGH/VIGOROUS
SHORTWAVE OVER ERN IA/SW WI POISED TO LIFT ENE INTO THE GREAT LAKES
AREA TONIGHT. AREA OF SNOW ASSOC WITH THIS FEATURE STRETCHES FROM
WRN LAKE SUPERIOR/SW UPR MI INTO WI AND NRN LAKE MI. FRONTAL
BOUNDARY OVER THE OHIO/TENNESSEE VALLEYS HAS EFFECTIVELY ROBBED THE
BETTER SURGE OF GULF MOISTURE N TO THE UPPER LAKES AHEAD OF WAVE.
PER 12Z RAOBS...PRECIPITABLE WATER VALUES UPWARDS OF 1 INCH ARE
SOUTH OF THE BOUNDARY WHILE VALUES ARE ONE-QUARTER TO ONE-HALF INCH
OVER THE NRN PLAINS...JUST A LITTLE ABOVE NORMAL FOR THIS TIME OF
YEAR. THE ROBBING OF MOISTURE BY THIS SRN WAVE/FRONT WILL WORK TO
KEEP SNOW ACCUMULATIONS IN CHECK DESPITE VIGOROUS DYNAMICS
ASSOCIATED WITH INCREASINGLY NEG-TILT UPR MS VALLEY SHORTWAVE.
MODEL CONSENSUS PCPN AMOUNTS INTO THIS EVENING ARE ROUGHLY 0.2 TO
0.25 INCHES. WITH SNOW RATIOS LIKELY AROUND 15 TO 1...ADVY FOR
GENERAL SNOWFALL OF 3 TO 4 INCHES STILL LOOKS ON TRACK AS THE SNOW
MAY FALL AT HEAVY AT TIMES FOR A WHILE INTO THE EVENING HRS.
SYNOPTIC SNOW WILL DIMINISH TO PATCHY -SN W TO E TONIGHT AS AREA OF
SNOW TIED TO STRONG FORCING AHEAD OF SHORTWAVE DEPARTS. ATTENTION
LATE TONIGHT THEN TURNS TO THE WRN COUNTIES WHERE STRONG NW WINDS
WILL DEVELOP IN THE WAKE OF SFC LOW MOVING ACROSS ERN LAKE SUPERIOR.
THE STRONG NW WINDS WILL ARRIVE OVER GOGEBIC/ONTONAGON COUNTIES
BEFORE REACHING THE KEWEENAW TUE MORNING. DEEP MOISTURE/CONVERGENT
CYCLONIC WNW FLOW...THE ADVECTION OF INCREASINGLY COLDER 8H TEMPS
ACROSS WRN LAKE SUPERIOR AND A DEEP DGZ SUGGEST VERY HVY LAKE
ENHANCED SNOW WILL LIKELY DEVELOP FROM KIWD N THRU THE KEWEENAW BY
DAYBREAK. COULD EASILY SEE SNOWFALL RATES OF 1-3IN/HR INTO TUESDAY
ACROSS THE HIGHER TERRAIN OF THE W. BLSN WILL ALSO BECOME AN
INCREASING HAZARD AS NW WINDS WILL GUST OVER 30MPH TO AS HIGH AS
40MPH...ESPECIALLY IN OPEN AREAS NEAR LAKE SUPERIOR. WHITE-OUTS WILL
BE A GOOD POSSIBILITY DUE TO COMBINATION OF HVY SNOW/BLSN INTO TUESDAY.
ERN COUNTIES WILL NOT GET INTO THE LAKE ENHANCED SNOW UNTIL WINDS
SHIFT FROM WEST TO NORTHWEST BEHIND COLD FROPA. AS 8H TEMPS SLOWLY
FALL TO AROUND -12 TO -13C OVER ERN LAKE SUPERIOR BY 00Z
WED...EXPECT LAKE ENHANCED SNOW TO GET GOING OVER ERN ALGER...NRN
SCHOOLCRAFT AND LUCE COUNTIES IN CYCLONIC WNW FLOW. ALTHOUGH BEST
MODEL OMEGA INITIALLY MAY STAY BLO DGZ RESULTING IN LOWER SNOW WATER
RATIOS...BELIEVE SNOW ACCUMS WILL INCREASE LATER IN THE DAY ON TUE
AND ESPECIALLY LATE TUE NIGHT AND WED AS COLDER 8H TEMPS CONTINUES TO
SEEP ACROSS ERN LAKE SUPERIOR AND LOW-LVL CONVERGENCE INCREASES WITH
FLOW VEERING NW. NW WINDS INCREASING TO 25-30 MPH...ESPECIALLY ALONG
THE LAKE SUPERIOR SHORE WILL ALSO ADD TO BLOWING SNOW AND LOWER
VSBYS TUE AFTERNOON INTO WEDNESDAY.
AS A RESULT OF CONDITIONS BECOMING INCREASINGLY MORE FAVORABLE FOR
ENHANCED SNOW AND BLOWING SNOW TUE AFTERNOON THROUGH WED
NIGHT...HAVE DECIDED TO UPGRADE WINTER STORM WATCH TO WINTER STORM
WARNING FOR ALGER...LUCE AND NRN SCHOOLCRAFT COUNTIES FOR LATE TUE
MORNING THROUGH WED NIGHT.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 429 PM EDT MON MAR 18 2013
ACTIVE LAKE EFFECT PERIOD FOR NORTHWESTERLY SNOW BELTS WILL CONTINUE
TUESDAY NIGHT INTO EARLY THURSDAY. AS UPPER LOW CLOSES OFF JUST EAST
OF THE AREA AND CYCLONIC FLOW COMBINES WITH H85 TEMPS IN THE -16 TO
-18 RANGE MODERATE TO HEAVY LAKE EFFECT SNOWS WILL CONTINUE. WINDS
WILL CONTINUE TO GUST OVER 35 MPH ESPECIALLY NEAR THE LAKESHORE
THROUGH THE DAY WEDNESDAY INTO WEDNESDAY NIGHT. WILL MAINTAIN THE
LONG DURATION WINTER STORM WARNING ACROSS THE WEST AND KEWEENAW
THROUGH THE DAY WEDNESDAY AND THE EAST INTO THURSDAY MORNING. LAKE
EFFECT SNOW TOTALS IN THE 12 TO 18 INCH RANGE SEEM LIKELY THROUGH
THE TUESDAY TO THURSDAY PERIOD.
LOW LEVEL WINDS BEGIN TO BECOME MORE NORTHERLY ON THURSDAY AS LAKE
EFFECT CONDITIONS BEGIN TO BECOME LESS FAVORABLE. AS MILDER AIR
WRAPS AROUND THE SLOWLY RETROGRADING UPPER LOW EXPECT 85H TEMPS TO
WARM INTO THE -8 TO -10 RANGE AS INVERSION LOWERS. THIS SHOULD
EFFECTIVELY END THE LAKE EFFECT BY LATE THURSDAY INTO EARLY FRIDAY.
OVERALL TREND INTO THE UPCOMING WEEKEND SHOULD FAVOR GENERALLY
TRANQUIL WEATHER WITH TEMPERATURES WITHIN A FEW DEGREES OF NORMAL.
MODELS OFFER SOME MINOR VARIATIONS WITH UPPER LOW DEPARTING THE
AREA AND UPPER PATTERN TRANSITIONING TO A MORE ZONAL FLOW WITH THE
MAIN STORM TRACK SOUTH OF THE AREA...FOR NOW WILL MAINTAIN A
CONSENSUS BLEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 201 PM EDT MON MAR 18 2013
LOW PRES APPROACHING FROM THE W WILL PUSH A BAND OF SNOW ACROSS
UPPER MI THIS AFTERNOON AND EVENING. SNOW SHOULD BEGIN AT KIWD BY
19Z...AT KCMX BY 20Z AND AT KSAW AROUND 21Z AND EXPECT CONDITIONS TO
LOWER QUICKLY TO IFR AT THOSE TIMES. SNOW SHOULD DIMINISH FOR A
WHILE TONIGHT AND MAY ALLOW CONDITIONS TO IMPROVE TO MVFR. THAT`S
MOST LIKELY TO HAPPEN AT KSAW. LATE TONIGHT...STRONG NW WINDS BEHIND
THE LOW WILL BRING MDT/HVY LAKE ENHANCED SNOW TO KIWD/KCMX WITH
CONDITIONS LIKELY FALLING TO LIFR.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 429 PM EDT MON MAR 18 2013
TIGHT PRES GRADIENT AHEAD OF THE LOW OVER NW MN WILL CONTINUE SE WINDS
UP TO 30KT TODAY. GALES WILL LIKELY OCCUR TOWARD MID LAKE PORTIONS
OF NCNTRL AND ERN LAKE SUPERIOR...IN PARTICULAR FROM AROUND
WHITEFISH PT NW TOWARD PASSAGE ISLAND. AFTER THE LOW EXITS TO THE
E...NORTHWEST GALES WILL DEVELOP FROM W TO E LATE TONIGHT/TUE. THE
GALES WILL THEN CONTINUE INTO WED OVER THE E HALF OF THE LAKE. WINDS
WILL SLOWLY DIMINISH TO UNDER 25KT FROM W TO E WED NIGHT/THU. THE
COMBINATION OF COLD AIR/STRONG WINDS/HIGH WAVES WILL LEAD TO PERIODS
OF HVY FREEZING SPRAY TUE THRU WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY FOR
MIZ001>004-009-084.
WINTER WEATHER ADVISORY UNTIL 5 AM EDT TUESDAY FOR MIZ006-007-
014-085.
WINTER STORM WARNING FROM 11 AM TUESDAY TO 8 AM EDT THURSDAY FOR
MIZ006-007-085.
WINTER WEATHER ADVISORY UNTIL 2 AM EDT /1 AM CDT/ TUESDAY FOR
MIZ005-010>013.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 2 PM TUESDAY TO 8 PM EDT
THURSDAY FOR LSZ243>245-248>251-264>267.
GALE WARNING UNTIL 2 PM EDT WEDNESDAY FOR LSZ264-266-267.
GALE WARNING FROM 2 PM TUESDAY TO 2 PM EDT WEDNESDAY FOR
LSZ243>251-265.
HEAVY FREEZING SPRAY WARNING FROM 5 AM EDT /4 AM CDT/ TUESDAY TO
8 AM EDT /7 AM CDT/ THURSDAY FOR LSZ162-240>242-263.
GALE WARNING FROM 8 AM EDT /7 AM CDT/ TUESDAY TO 2 PM EDT /1 PM
CDT/ WEDNESDAY FOR LSZ162-240>242-263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...MZ
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
201 PM EDT MON MAR 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 551 AM EDT MON MAR 18 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A VIGOROUS LOOKING
SHORTWAVE TROF MOVING ACROSS THE NRN PLAINS TOWARD THE UPPER
MISSISSIPPI VALLEY. BAND OF SNOW HAS BEEN SLOWLY ORGANIZING DURING
THE NIGHT ACROSS MN AHEAD OF FEATURE. FRONTAL BOUNDARY DRAPPED
ACROSS THE OHIO/TENNESSEE VALLEYS IS EFFECTIVELY PREVENTING A GOOD
SURGE OF MOISTURE N TO THE UPPER LAKES AHEAD OF WAVE. PER 00Z
RAOBS...PRECIPITABLE WATER VALUES UPWARDS OF 1 INCH ARE SOUTH OF
THE BOUNDARY WHILE VALUES ARE ONE-QUARTER TO ONE-HALF INCH OVER THE
NRN PLAINS...JUST A LITTLE ABOVE NORMAL FOR THIS TIME OF YEAR. THIS
WILL WORK TO KEEP SNOW ACCUMULATIONS IN CHECK DESPITE VIGOROUS
DYNAMICS ASSOCIATED WITH SHORTWAVE BECOMING INCREASINGLY NEGATIVELY
TILTED AS IT MOVES ACROSS THE WRN GREAT LAKES LATE THIS
AFTN/TONIGHT.
OVERALL...FCST FOR TODAY/TONIGHT WAS IN GOOD SHAPE...SO NO MAJOR
ADJUSTMENTS WERE MADE. SLOWED TIMING OF SNOW JUST A BIT BASED ON
OVERNIGHT RADAR TRENDS AND MODEL TRENDS. MODEL CONSENSUS PCPN
AMOUNTS ARE ROUGHLY 0.2 TO 0.4 INCHES. WITH SNOW RATIOS LIKELY
AROUND 15 TO 1...ADVY FOR GENERAL SNOWFALL OF 3 TO 6 INCHES LOOKS ON
TRACK. MOST LOCATIONS WILL PROBABLY BE IN THE 3-4 INCH RANGE...AND
THE SNOW MAY FALL AT DECENT RATE FOR A WHILE.
SNOW WILL DIMINISH TO PATCHY -SN W TO E TONIGHT AS BAND OF SNOW TIED
TO STRONG FORCING AHEAD OF SHORTWAVE DEPARTS. ATTENTION OVERNIGHT
THEN TURNS TO THE W WHERE STRONG NW WINDS WILL DEVELOP IN THE WAKE
OF SFC LOW MOVING ACROSS LAKE SUPERIOR. WHILE THERE IS SOME
UNCERTAINTY IN TIMING THE ARRIVAL OF THE STRONG NW WINDS...WHICH
WILL ARRIVE OVER GOGEBIC/ONTONAGON COUNTIES BEFORE THE
KEWEENAW...DEEP MOISTURE/CONVERGENT CYCLONIC FLOW AND A DEEP DGZ
SUGGEST VERY HVY LAKE ENHANCED SNOW WILL LIKELY DEVELOP FROM KIWD N
THRU THE KEWEENAW BY DAYBREAK. COULD EASILY SEE SNOWFALL RATES OF
1-3IN/HR INTO TUE MORNING ACROSS THE HIGHER TERRAIN OF THE W. BLSN
WILL ALSO BECOME AN INCREASING HAZARD AS NW WINDS WILL GUST OVER
30MPH TO AS HIGH AS 40MPH...ESPECIALLY IN OPEN AREAS NEAR LAKE
SUPERIOR. WHITE-OUTS WILL BE A GOOD POSSIBILITY DUE TO COMBINATION
OF HVY SNOW/BLSN.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 551 AM EDT MON MAR 18 2013
MODELS AGREE THAT STRONG SHORTWAVE MOVING THROUGH THE REGION TODAY
HELPS TO ESTABLISH LOW-MID LEVEL TROUGHING THROUGH THE WEEK. ONCE
SFC-H85 LOWS PUSH EAST OF LK SUPERIOR...EXPECT COLD AIR TO POUR
ACROSS THE ENTIRE GREAT LAKES REGION. SINCE THE TROUGH IS NEARLY
STATIONARY A LOT OF MOISTURE THROUGH H7 PERSISTS ACROSS THE REGION
THROUGH AT LEAST WEDNESDAY. ENOUGH COLD AIR IN BLYR TO SUPPORT AT
LEAST MODERATE LK EFFECT SNOWS THROUGH MIDWEEK BEFORE CONDITIONS
BECOME MORE MARGINAL BY LATE WEEK AS MOISTURE ABOVE H9 DIMINISHES
AND LOW-LEVEL FLOW BECOMES NOT AS CYCLONIC. PROLONGED PERIOD OF
MODERATE LK EFFECT SNOWS EXPECTED WITH POTENTIAL HEAVY LK EFFECT AT
TIMES THROUGH WEDNESDAY GIVEN DEEP MOISTURE IN PLACE...STRONGEST
LOW-LEVEL CONVERGENCE AND GREATEST INSTABILITY WITH DELTA T/S OVER
15C AND LAKE EQL TOWARD 10KFT. SOUNDINGS ALSO SHOW MAJORITY OF LAKE
CONVECTIVE LAYER WITHIN THE DGZ WHICH HELPS BOOST SLR/S OVER 20:1.
OTHER FACTOR TUESDAY/TUESDAY NIGHT AND INTO WEDNESDAY MORNING WILL
BE STRONG WINDS WITH OVER 30 KTS LOCATED WITHIN THE BLYR. GUSTS OVER
35KT/40 MPH SEEM POSSIBLE IN THE MOST VIGOROUS LK EFFECT CONVECTION.
BLOWING SNOW WILL INCREASE BY LATER TUESDAY AFTN IN AREAS FAVORED BY
NW WINDS AND THIS HAZARD WILL CONTINUE THROUGH MUCH OF WEDNESDAY.
A COUPLE MAIN ISSUES TO SORT OUT AND THESE ARE NOT TRIVIAL AS THEY
IMPACTED HEADLINE DECISIONS THIS MORNING. MAIN ISSUE THROUGH TUESDAY
IS THERE APPEARS TO BE A BREAK BTWN THE SYNOPTIC SNOW THAT MOVES
THROUGH THIS AFTN/TONIGHT AND INCREASING LK ENHANCED SNOW OVER EAST
ON TUESDAY AFTN. LOCAL WRF AND REGIONAL GEM AGRESSIVE IN DEVELOPING
SFC TROUGH OVER EASTERN CWA ON TUESDAY MORNING TO THE SOUTH OF
PRIMARY SFC LOW OVER EASTERN LK SUPERIOR. COARSER GFS HINTS AT THIS
IDEA AS WELL. WINDS AHEAD OF TROUGH BACK SW SO THAT LK EFFECT ISSUES
PROBABLY WILL NOT DEVELOP OVER THE FAR EAST UNTIL AFTER 18Z ON
TUESDAY. ONCE TROUGH SHIFTS THROUGH...LK EFFECT COULD BECOME QUITE
INTENSE JUST IN WAKE OF TROUGH AS CONVERGENCE RAMPS UP AND COLD AIR
ARRIVES LEADING TO QUICKLY INCREASING OVER-WATER INSTABILITY. GIVEN
CERTAIN BLSN HAZARD ALONG WITH HEAVIER LK ENHANCED SNOWFALL...A
WARNING MAY EVENTUALLY BE NEEDED. SINCE THERE WILL BE ENOUGH OF A
GAP BTWN THE SYNOPTIC SNOW AND HEAVIER LK ENHANCED SNOW LATER
TUESDAY DECIDED IN FAVOR OF WINTER STORM WATCH FOR EASTERN CWA NEAR
LK SUPERIOR 12Z TUESDAY THROUGH 12Z THURSDAY. DID NOT GET TOO
SPECIFIC WITH TIMING SINCE SOME MODELS DO SHOW QUICKER ONSET OF LK
ENHANCED SNOW THAN GEM-REGIONAL AND LOCAL-WRF...ESPECIALLY IN THE
MUNISING AND GRAND MARAIS AREAS. WESTERN TIER OF CWA IS MORE CLEAR
CUT. MAIN ISSUE OVER THE WEST IS HOW LONG TO RUN THE WARNING. KEPT
IT PRETTY SIMPLE AT THIS POINT AND KEPT WARNING IN PLACE UNTIL WINDS
IN BLYR BEGIN TO DECREASE BLO 25 KTS AND WHEN DEEPER MOISTURE STARTS
TO CUT OUT. ON BOTH ACCOUNTS IT APPEARS SUITABLE CUTOFF WAS DAYBREAK
ON THURSDAY MORNING. MORE LK EFFECT CONTINUES ON THURSDAY...BUT
SHOULD BE BEGINNING TO SHOW DIMINISHING TREND COMPARED TO MORE
FAVORABLE SETUP IN PLACE TUESDAY AND WEDNESDAY.
LK EFFECT DIMINISHES FURTHER INTO FRIDAY BUT PROBABLY WILL NOT GO
AWAY COMPLETELY AS LIGHT WIND PERSISTS OFF LK SUPERIOR. THOUGH H85
TEMPS ARE WARMING...COOL ENOUGH BENEATH LOWERING INVERSION TO HAVE
SOME LGT SNOW SHOWERS/FLURRIES. NO SIGNIFICANT WX INTO THE WEEKEND
BUT NOT ALL THAT WARM EITHER AS GENERAL TROUGHING CONTINUES. SINCE
MOST OF FOCUS WAS ON SNOW/BLSN AND HEADLINES...USED MODEL CONSENSUS
FOR THE FORECAST BEYOND THURSDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 201 PM EDT MON MAR 18 2013
LOW PRES APPROACHING FROM THE W WILL PUSH A BAND OF SNOW ACROSS
UPPER MI THIS AFTERNOON AND EVENING. SNOW SHOULD BEGIN AT KIWD BY
19Z...AT KCMX BY 20Z AND AT KSAW AROUND 21Z AND EXPECT CONDITIONS TO
LOWER QUICKLY TO IFR AT THOSE TIMES. SNOW SHOULD DIMINISH FOR A
WHILE TONIGHT AND MAY ALLOW CONDITIONS TO IMPROVE TO MVFR. THAT`S
MOST LIKELY TO HAPPEN AT KSAW. LATE TONIGHT...STRONG NW WINDS BEHIND
THE LOW WILL BRING MDT/HVY LAKE ENHANCED SNOW TO KIWD/KCMX WITH
CONDITIONS LIKELY FALLING TO LIFR.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 551 AM EDT MON MAR 18 2013
AS LOW PRES OVER THE EASTERN DAKOTAS MOVES E...TIGHT PRES GRADIENT
AHEAD OF THE LOW WILL BRING SE WINDS UP TO 30KT TODAY. GALES WILL
LIKELY OCCUR TOWARD MID LAKE PORTIONS OF NCNTRL AND ERN LAKE
SUPERIOR...IN PARTICULAR FROM AROUND WHITEFISH PT NW TOWARD PASSAGE
ISLAND. AFTER THE LOW EXITS TO THE E...NORTHWEST GALES WILL DEVELOP
FROM W TO E LATE TONIGHT/TUE. THE GALES WILL THEN CONTINUE INTO WED
OVER THE E HALF OF THE LAKE. WINDS WILL SLOWLY DIMINISH TO UNDER 25KT
FROM W TO E WED NIGHT/THU. THE COMBINATION OF COLD AIR/STRONG
WINDS/HIGH WAVES WILL LEAD TO PERIODS OF HVY FREEZING SPRAY TUE THRU
WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY FOR
MIZ001>004-009-084.
WINTER WEATHER ADVISORY UNTIL 5 AM EDT TUESDAY FOR MIZ006-007-
014-085.
WINTER STORM WATCH FROM TUESDAY MORNING THROUGH THURSDAY MORNING
FOR MIZ006-007-085.
WINTER WEATHER ADVISORY UNTIL 2 AM EDT TUESDAY FOR MIZ005-013.
WINTER WEATHER ADVISORY UNTIL 1 AM CDT TUESDAY FOR MIZ010>012.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 2 PM TUESDAY TO 8 PM EDT
THURSDAY FOR LSZ243>245-248>251-264>267.
GALE WARNING UNTIL 2 PM EDT WEDNESDAY FOR LSZ264-266-267.
GALE WARNING FROM 2 PM TUESDAY TO 2 PM EDT WEDNESDAY FOR
LSZ243>251-265.
HEAVY FREEZING SPRAY WARNING FROM 5 AM EDT /4 AM CDT/ TUESDAY TO
8 AM EDT /7 AM CDT/ THURSDAY FOR LSZ162-240>242-263.
GALE WARNING FROM 8 AM EDT /7 AM CDT/ TUESDAY TO 2 PM EDT /1 PM
CDT/ WEDNESDAY FOR LSZ162-240>242-263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
517 PM EDT MON MAR 18 2013
.SYNOPSIS...
A STRONG COLD FRONT WILL SWEEP ACROSS THE REGION TONIGHT...USHERING
IN DRY AIR FOR TUESDAY THROUGH THURSDAY. EXPECT UNSETTLED WEATHER TO
RETURN TO THE SOUTHEAST STATES THIS WEEKEND AND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
AS OF 445 PM...THE MAIN ALTERATION TO THE FORECAST WAS TO EXPAND
POPS EAST ACROSS THE CWFA MUCH QUICKER THAN PREVIOUSLY FORECAST...AS
NUMEROUS SHOWERS NOW EXTEND AS FAR EAST AS I-77. THERE IS ALSO A
DECENT AMOUNT OF ELEVATED INSTABILITY ACROSS THE WESTERN ZONES...AS
EVIDENCED BY MUCAPE APPROACHING 500 J/KG PER SPC MESOANALYSIS. THIS
IS RESULTING IN SCATTERED TO NUMEROUS TS ACROSS THE WESTERN HALF OF
THE AREA. THEREFORE...WE HAVE BEEFED UP THE TS MENTION FOR ALL AREAS
IN THE FORECAST SUITE FOR THE REMAINDER OF THE AFTERNOON/EVENING. WE
ARE SEEING PLENTY OF DISCRETE CELLS ACROSS THE TENN VALLEY... SOME
WITH MINI-SUPERCELL STRUCTURES. HOWEVER...THE WEDGE BOUNDARY HAS NOT
MADE MUCH NORTHWARD PROGRESS ACROSS THE CAROLINAS/NORTH GEORGIA OVER
THE LAST FEW HOURS. WE WILL HAVE TO CLOSELY MONITOR THE PROGRESS OF
THIS BOUNDARY WITH TIME...AS ANY PROGRESSION INTO OUR SOUTHERN ZONES
WILL POSE AN INCREASED CONCERN FOR SEVERE WEATHER. EVEN A TORNADO IS
POSSIBLE WITH ANY MINI-SUPERCELLS INTERACTING WITH THE BOUNDARY. THE
SECOND AREA OF CONCERN WILL BE WITH THE QLCS APPROACHING THE
SOUTHWEST MTNS...WHERE THERE APPEARS TO BE A BIT MORE IN THE WAY OF
BOUNDARY LAYER ROOTED INSTABILITY. EVERYWHERE ELSE...SEVERE WEATHER
CONCERNS SHOULD BE LIMITED TO PERHAPS AN ISOLATED HAIL THREAT.
AS OF 230 PM ...THE WEDGE CONTINUES TO HOLD FIRM WITH LOWS CLOUDS
AND AREAS OF MAINLY DRIZZLE EAST OF THE MOUNTAINS. RADAR IS SHOWING
SHOWERS BECOMING MORE WIDESPREAD OVER THE MOUNTAINS...AND A FEW
THUNDERSTORMS MAY ALSO HOLD TOGETHER TO AFFECT FAR WESTERN NC AND
THE THE TN BORDER COUNTIES BY 4 PM. THIS IS ALL HANDLED WELL IN THE
GRIDS AT THE MOMENT. TEMPS REMAIN QUITE COOL WITH LOW TO MID 40S
WIDESPREAD...EXCEPT SOME LOW TO MID 50S ON THE FRINGES OF THE WEDGE
IN THE FAR W AND S.
MODELS INDICATE THAT THE WEDGE WILL HOLD TOUGH AT LEAST THROUGH 06Z
AND REALLY NOT WASH OUT UNTIL AFTER THE PASSAGE OF A COLD FRONT
BEGINNING AROUND MIDNIGHT IN THE MOUNTAINS...AND LATE TONIGHT IN THE
FAR EASTERN COUNTIES. MESO MODELS LIKE THE HRRR AND OUR LOCAL WRF
INDICATE THAT THE MAIN AREA OF SHOWERS ASSOCIATED WITH A PASSING
UPPER WAVE WILL AFFECT THE AREA FROM MID AFTERNOON INTO EARLY
EVENING AND THEN SHIFT TO THE EAST OF THE AREA. ANOTHER BAND OF
SHOWERS IS THEN FORECAST TO ACCOMPANY THE COLD FRONT...BUT MAY BE
MORE SCATTERED EAST OF THE MOUNTAINS. SBCAPES REMAIN QUITE LOW OR
NON-EXISTENT DUE TO THE WEDGE...BUT MUCAPES APPEAR SUFFICIENT FOR
SOME ELEVATED THUNDER ALONG THE SOUTHERN AND WESTERN BOUNDARIES OF
THE WEDGE MODIFIED AIR. TEMPERATURES OVERNIGHT WILL REMAIN GENERALLY
STEADY OR EVEN SLOWLY RISE AS WEDGE SLOWLY ERODES. USED A BLEND OF 3
HOURLY MOS NUMBERS TO TRY AND CAPTURE THE TEMP TREND.
DEEP LAYER DRYING IS FORECAST TO OCCUR ON TUE BEHIND THE COLD FRONT
AS THE UPPER FLOW BECOMES ZONAL BEHIND THE DEPARTING UPPER WAVE AND
SURFACE HIGH PRESSURE RIDGES EAST. DOWNSLOPE FLOW ON TUE WILL
COUNTER COLD ADVECTION TO A LARGE EXTENT...AND WITH PLENTY OF
SUNSHINE TEMPS ARE FORECAST TO CLIMB WELL INTO THE 60S OUTSIDE THE
MOUNTAINS...WITH 50S IN THE MOUNTAIN VALLEYS. USED MOS BLEND TO
GENERATE TEMPS.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
AS OF 250 PM MONDAY...MODELS CONTINUE TO SHOW A CHANNELED SHORT WAVE
ROTATING AROUND A LARGE UPR LVL VORTEX OVR THE GREAT LAKES/SRN
QUEBEC LATE WED AND WED NITE. THE GUIDANCE ALSO HAS A WEAKER SHORT
WAVE MOVING ALONG THE GULF COAST DURING THIS TIME. AT THE SFC...
THESE WAVES LEAD TO A DOUBLE-BARRELED LOW PRESSURE SYSTEM...ONE NRN
STREAM CLIPPER AND A SRN STREAM FAST MOVING GULF COAST LOW. SOME OF
THE GUIDANCE IS NOW DEVELOPING LIGHT PRECIP WITH THE SRN STREAM LOW.
HOWEVER...THE LOW LEVELS REMAIN QUITE DRY...SO EXPECT NO MORE THAN
MOSTLY CLOUDY SKIES FROM MAINLY MID AND HIGH LEVEL CLOUDS. MDLS
STILL SHOWING THE NRN STREAM CLIPPER PRODUCING LIGHT PRECIP ACROSS
MAINLY THE TN BORDER COUNTIES OF THE NC MTNS. TEMPS AND THICKNESSES
HAVE COME IN QUITE COLDER WITH THESE SYSTEMS. THEREFORE...IT APPEARS
THAT ANY PRECIP ACROSS THE MTNS WILL BE MAINLY SNOW SHOWERS...
POSSIBLY MIXED WITH RAIN AT ONSET. GUIDANCE BLEND OF QPF SUGGESTING
UP TO AN INCH OF SNOW POSSIBLE ACROSS THE USUAL AREAS OF THE NRN
MTNS. IF SOMETHING WAS TO FALL OUTSIDE OF THE MTNS...IT WOULD BE
SPRINKLES OR FLURRIES. SUSTAINED WINDS HAVE COME IN LOWER ON THE
LATEST GUIDANCE FOR WED...BUT IT SHOULD STILL BE BREEZY WITH GUSTY
WINDS.
LOWS TUE NITE 5 TO 10 DEGREES BELOW NORMAL ACROSS THE MTNS AND A FEW
DEGREES BELOW NORMAL ELSEWHERE. THE 20TH IS THE FIRST DAY OF SPRING
WHICH IS THE START OF THE FROST/FREEZE PROGRAM OUTSIDE OF THE MTNS
FOR OUR CWFA. I DO HAVE SOME AREAS AROUND FREEZING. HOWEVER...WILL
HOLD OFF ON A FREEZE WATCH AS THERE WILL BE QUITE A BIT OF MID AND
HIGH CLOUDS THAT SHUD KEEP TEMPS FROM FALLING DRAMATICALLY. HIGHS
WED AROUND 5 DEGREES BELOW NORMAL
SKIES CLEAR OUTSIDE OF THE MTNS LATE WED NITE AND OVER THE MTNS THU.
LOWS AROUND 10 DEGREES BELOW NORMAL. SHUD THIS TREND CONTINUE...THEN
A FREEZE WARNING WOULD BE NEEDED FOR MUCH OF THE CWFA OUTSIDE OF THE
MTNS. LOOKS TO BE A BREEZY AND POSSIBLY WINDY DAY THU WITH GUSTY
WINDS AGAIN. HIGHS WILL BE 10 TO 15 DEGREES BELOW NORMAL WITH THE
COLD AIR MASS MOVING IN.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 220 PM TUESDAY...DIFFERENCES SEEN IN THE MEDIUM RANGE MODELS
IN TIMING AND LOCATION OF LOW DEVELOPMENT. THIS PERIOD BEGINS AT 00Z
FRIDAY AND AT THAT TIME THE GFS AND ECMWF AGREE ON LOCATION OF UPPER
LOW OVER QUEBEC AND THE DEPARTING WEAK SURFACE HIGH OVER THE
CAROLINAS. FAIRLY GOOD INFLOW FROM THE GULF ON FRIDAY AHEAD OF THE
LOW OVER EAST TEXAS. ALTHOUGH THERE IS SOME GENERAL AGREEMENT ON
LOWS CROSSING THE SOUTHEAST STATES...THE CANADIAN IS CLOSER TO THE
ECMWF AND THE GFS CREATES A VASTLY DIFFERENT SOLUTION ON THE LOW
DEVELOPMENT OVER TENNESSEE SATURDAY NIGHT INTO SUNDAY. THE GFS SETS
UP A BETTER COLD AIR WEDGE SATURDAY INTO SATURDAY
NIGHT...HOWEVER...THE CENTER OF THE HIGH WILL BE FAR NORTH IN
CANADA. THE GFS DEVELOPS A DEEP LOW NEAR MEMPHIS LATE SATURDAY AND
TRACKS IT EAST CROSSING THE NC MTNS LATE SUNDAY. KEEPING A DIURNAL
PRECIP TRANSITION FOR THE MTNS AND NC FOOTHILLS WITH NIGHT TIME SNOW
AND DAYTIME RAIN AS SOUNDINGS TRENDING TOWARD EITHER RAIN OR SNOW.
BOTH GFS AND ECMWF DEVELOP AND COASTAL LOW TO START THE NEW WEEK
WITH THE FIRST LOW GIVING ITS ENERGY TO THE NEW LOW ON THE NC COAST
AND THIS MOVES EAST OVER THE ATLANTIC. DRYING TO OCCUR AT THE END OF
THE CURRENT SEVEN DAY WITH HIGH PRESSURE CROSSING THE PLAINS.
DAYTIME HIGHS THROUGH THIS MEDIUM RANGE AT LEAST TEN DEGREES BELOW
NORMAL AND NIGHT TIME LOWS 2 TO 5 DEGREES BELOW NORMAL DUE TO THE
CLOUD COVER.
&&
.AVIATION /21Z MONDAY THROUGH SATURDAY/...
AT KCLT...COLD AIR WEDGE HAS LOCKED INTO THE AREA WITH CIGS HOLDING
STEADY AROUND 005OVC. AREAS OF DRIZZLE/FOG CAUSING SOME VSBY
RESTRICTIONS AS WELL. CURRENT INDICATIONS ARE THAT THERE WILL BE
LITTLE CHANGE IN THE OVERALL CONDITIONS UNTIL AFTER A COLD FRONT
MOVES THROUGH LATE TONIGHT WHICH WILL SHIFT WINDS TO THE NW. EXPECT
A WAVE OF SHOWERS TO AFFECT THE AIRFIELD THIS EVENING CAUSING VSBY
RESTRICTIONS...WITH FOG KEEPING VSBYS LOW AFTERWARD UNTIL LATE
TONIGHT. EXPECT RAPID CLEARING AFTER 12Z ON TUE.
ELSEWHERE...THE REST OF THE REGION IS SHARING IN THE COLD AIR
DAMMING CONDITIONS. THIS MEANS GENERALLY IFR TO LIFR CIGS THROUGH
MOST OF TONIGHT. A WAVE OF SHOWERS WILL MOVE ACROSS THE AREA THIS
AFTERNOON INTO THIS EVENING RESTRICTING VSBYS. FOG WILL CONTINUE TO
THE RESTRICT VSBYS UNTIL AFTER A COLD FORNT MOVES THROUGH LATE
TONIGHT. EXPECT CLEARING EARLY TUE MORNING. THE ONLY AIRFIELD WHERE
THUNDER IS MENTIONED IS AT KAND AS WEDGE BOUNDARY WILL BE CLOSEST
THERE.
OUTLOOK...GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH THURSDAY.
CONFIDENCE TABLE...
21-03Z 03-09Z 09-15Z 15-21Z
KCLT MED 71% MED 72% LOW 50% HIGH 100%
KGSP MED 70% MED 73% MED 60% HIGH 100%
KAVL MED 77% MED 70% MED 70% HIGH 100%
KHKY MED 76% MED 72% MED 69% HIGH 100%
KGMU MED 70% MED 73% MED 60% HIGH 100%
KAND MED 61% MED 66% MED 62% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.FIRE WEATHER...
A WARM...DRY AND WINDY AIR MASS WILL MOVE IN TUE BEHIND A DEPARTING
COLD FRONT. MINIMUM RH VALUES WILL BE LESS THAN 25 PERCENT ACROSS
MUCH OF THE AREA WITH GUSTY WINDS DEVELOPING. ALTHOUGH FUEL MOISTURE
IS RELATIVELY HIGH AND PRECIP MOVES ACROSS THE AREA TONIGHT...NC
FOREST SERVICE IS CONCERNED ABOUT THE DRYING AND DEVELOPING WINDS.
THEREFORE...A FIRE DANGER STATEMENT WILL BE ISSUED FOR TUE. SC LAND
MANAGERS ARE NOT AS CONCERNED FOR THE UPSTATE AND NE GA FUEL
MOISTURE WAS NEAR 20 PERCENT MON AFTERNOON. THEREFORE...NO STATEMENT
FOR SC OR GA. BREEZY AND GUSTY CONDITIONS RETURN WED AFTERNOON WITH
ANOTHER DAY OF VERY LOW RH VALUES. FIRE DANGER STATEMENTS MAY BE
NEEDED THEN AS WELL.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...JDL/LG
SHORT TERM...RWH
LONG TERM...DEO
AVIATION...LG
FIRE WEATHER...
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
311 PM EDT MON MAR 18 2013
.SYNOPSIS...
A STRONG COLD FRONT WILL SWEEP ACROSS THE REGION TONIGHT...USHERING
IN DRY AIR FOR TUESDAY THROUGH THURSDAY. EXPECT UNSETTLED WEATHER TO
RETURN TO THE SOUTHEAST STATES THIS WEEKEND AND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
AS OF 230 PM ...THE WEDGE CONTINUES TO HOLD FIRM WITH LOWS CLOUDS
AND AREAS OF MAINLY DRIZZLE EAST OF THE MOUNTAINS. RADAR IS SHOWING
SHOWERS BECOMING MORE WIDESPREAD OVER THE MOUNTAINS...AND A FEW
THUNDERSTORMS MAY ALSO HOLD TOGETHER TO AFFECT FAR WESTERN NC AND
THE THE TN BORDER COUNTIES BY 4 PM. THIS IS ALL HANDLED WELL IN THE
GRIDS AT THE MOMENT. TEMPS REMAIN QUITE COOL WITH LOW TO MID 40S
WIDESPREAD...EXCEPT SOME LOW TO MID 50S ON THE FRINGES OF THE WEDGE
IN THE FAR W AND S.
MODELS INDICATE THAT THE WEDGE WILL HOLD TOUGH AT LEAST THROUGH 06Z
AND REALLY NOT WASH OUT UNTIL AFTER THE PASSAGE OF A COLD FRONT
BEGINNING AROUND MIDNIGHT IN THE MOUNTAINS...AND LATE TONIGHT IN THE
FAR EASTERN COUNTIES. MESO MODELS LIKE THE HRRR AND OUR LOCAL WRF
INDICATE THAT THE MAIN AREA OF SHOWERS ASSOCIATED WITH A PASSING
UPPER WAVE WILL AFFECT THE AREA FROM MID AFTERNOON INTO EARLY
EVENING AND THEN SHIFT TO THE EAST OF THE AREA. ANOTHER BAND OF
SHOWERS IS THEN FORECAST TO ACCOMPANY THE COLD FRONT...BUT MAY BE
MORE SCATTERED EAST OF THE MOUNTAINS. SBCAPES REMAIN QUITE LOW OR
NON-EXISTANT DUE TO THE WEDGE...BUT MUCAPES APPEAR SUFFICIENT FOR
SOME ELEVATED THUNDER ALONG THE SOUTHERN AND WESTERN BOUNDARIES OF
THE WEDGE MODIFIED AIR. TEMPERATURES OVERNIGHT WILL REMAIN GENERALLY
STEADY OR EVEN SLOWLY RISE AS WEDGE SLOWLY ERODES. USED A BLEND OF 3
HOURLY MOS NUMBERS TO TRY AND CAPTURE THE TEMP TREND.
DEEP LAYER DRYING IS FORECAST TO OCCUR ON TUE BEHIND THE COLD FRONT
AS THE UPPER FLOW BECOMES ZONAL BEHIND THE DEPARTING UPPER WAVE AND
SURFACE HIGH PRESSURE RIDGES EAST. DOWNSLOPE FLOW ON TUE WILL
COUNTER COLD ADVECTION TO A LARGE EXTENT...AND WITH PLENTY OF
SUNSHINE TEMPS ARE FORECAST TO CLIMB WELL INTO THE 60S OUTSIDE THE
MOUNTAINS...WITH 50S IN THE MOUNTAIN VALLEYS. USED MOS BLEND TO
GENERATE TEMPS.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
AS OF 250 PM MONDAY...MODELS CONTINUE TO SHOW A CHANNELED SHORT WAVE
ROTATING AROUND A LARGE UPR LVL VORTEX OVR THE GREAT LAKES/SRN
QUEBEC LATE WED AND WED NITE. THE GUIDANCE ALSO HAS A WEAKER SHORT
WAVE MOVING ALONG THE GULF COAST DURING THIS TIME. AT THE SFC...
THESE WAVES LEAD TO A DOUBLE-BARRELED LOW PRESSURE SYSTEM...ONE NRN
STREAM CLIPPER AND A SRN STREAM FAST MOVING GULF COAST LOW. SOME OF
THE GUIDANCE IS NOW DEVELOPING LIGHT PRECIP WITH THE SRN STREAM LOW.
HOWEVER...THE LOW LEVELS REMAIN QUITE DRY...SO EXPECT NO MORE THAN
MOSTLY CLOUDY SKIES FROM MAINLY MID AND HIGH LEVEL CLOUDS. MDLS
STILL SHOWING THE NRN STREAM CLIPPER PRODUCING LIGHT PRECIP ACROSS
MAINLY THE TN BORDER COUNTIES OF THE NC MTNS. TEMPS AND THICKNESSES
HAVE COME IN QUITE COLDER WITH THESE SYSTEMS. THEREFORE...IT APPEARS
THAT ANY PRECIP ACROSS THE MTNS WILL BE MAINLY SNOW SHOWERS...
POSSIBLY MIXED WITH RAIN AT ONSET. GUIDANCE BLEND OF QPF SUGGESTING
UP TO AN INCH OF SNOW POSSIBLE ACROSS THE USUAL AREAS OF THE NRN
MTNS. IF SOMETHING WAS TO FALL OUTSIDE OF THE MTNS...IT WOULD BE
SPRINKLES OR FLURRIES. SUSTAINED WINDS HAVE COME IN LOWER ON THE
LATEST GUIDANCE FOR WED...BUT IT SHOULD STILL BE BREEZY WITH GUSTY
WINDS.
LOWS TUE NITE 5 TO 10 DEGREES BELOW NORMAL ACROSS THE MTNS AND A FEW
DEGREES BELOW NORMAL ELSEWHERE. THE 20TH IS THE FIRST DAY OF SPRING
WHICH IS THE START OF THE FROST/FREEZE PROGRAM OUTSIDE OF THE MTNS
FOR OUR CWFA. I DO HAVE SOME AREAS AROUND FREEZING. HOWEVER...WILL
HOLD OFF ON A FREEZE WATCH AS THERE WILL BE QUITE A BIT OF MID AND
HIGH CLOUDS THAT SHUD KEEP TEMPS FROM FALLING DRAMATICALLY. HIGHS
WED AROUND 5 DEGREES BELOW NORMAL
SKIES CLEAR OUTSIDE OF THE MTNS LATE WED NITE AND OVER THE MTNS THU.
LOWS AROUND 10 DEGREES BELOW NORMAL. SHUD THIS TREND CONTINUE...THEN
A FREEZE WARNING WOULD BE NEEDED FOR MUCH OF THE CWFA OUTSIDE OF THE
MTNS. LOOKS TO BE A BREEZY AND POSSIBLY WINDY DAY THU WITH GUSTY
WINDS AGAIN. HIGHS WILL BE 10 TO 15 DEGREES BELOW NORMAL WITH THE
COLD AIR MASS MOVING IN.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 220 PM TUESDAY...DIFFERENCES SEEN IN THE MEDIUM RANGE MODELS
IN TIMING AND LOCATION OF LOW DEVELOPMENT. THIS PERIOD BEGINS AT 00Z
FRIDAY AND AT THAT TIME THE GFS AND ECMWF AGREE ON LOCATION OF UPPER
LOW OVER QUEBEC AND THE DEPARTING WEAK SURFACE HIGH OVER THE
CAROLINAS. FAIRLY GOOD INFLOW FROM THE GULF ON FRIDAY AHEAD OF THE
LOW OVER EAST TEXAS. ALTHOUGH THERE IS SOME GENERAL AGREEMENT ON
LOWS CROSSING THE SOUTHEAST STATES...THE CANADIAN IS CLOSER TO THE
ECMWF AND THE GFS CREATES A VASTLY DIFFERENT SOLUTION ON THE LOW
DEVELOPMENT OVER TENNESSEE SATURDAY NIGHT INTO SUNDAY. THE GFS SETS
UP A BETTER COLD AIR WEDGE SATURDAY INTO SATURDAY
NIGHT...HOWEVER...THE CENTER OF THE HIGH WILL BE FAR NORTH IN
CANADA. THE GFS DEVELOPS A DEEP LOW NEAR MEMPHIS LATE SATURDAY AND
TRACKS IT EAST CROSSING THE NC MTNS LATE SUNDAY. KEEPING A DIURNAL
PRECIP TRANSITION FOR THE MTNS AND NC FOOTHILLS WITH NIGHT TIME SNOW
AND DAYTIME RAIN AS SOUNDINGS TRENDING TOWARD EITHER RAIN OR SNOW.
BOTH GFS AND ECMWF DEVELOP AND COASTAL LOW TO START THE NEW WEEK
WITH THE FIRST LOW GIVING ITS ENERGY TO THE NEW LOW ON THE NC COAST
AND THIS MOVES EAST OVER THE ATLANTIC. DRYING TO OCCUR AT THE END OF
THE CURRENT SEVEN DAY WITH HIGH PRESSURE CROSSING THE PLAINS.
DAYTIME HIGHS THROUGH THIS MEDIUM RANGE AT LEAST TEN DEGREES BELOW
NORMAL AND NIGHT TIME LOWS 2 TO 5 DEGREES BELOW NORMAL DUE TO THE
CLOUD COVER.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
AT KCLT...COLD AIR WEDGE HAS LOCKED INTO THE AREA WITH CIGS HOLDING
STEADY AROUND 005OVC. AREAS OF DRIZZLE/FOG CAUSING SOME VSBY
RESTRICTIONS AS WELL. CURRENT INDICATIONS ARE THAT THERE WILL BE
LITTLE CHANGE IN THE OVERALL CONDITIONS UNTIL AFTER A COLD FRONT
MOVES THROUGH LATE TONIGHT WHICH WILL SHIFT WINDS TO THE NW. EXPECT
A WAVE OF SHOWERS TO AFFECT THE AIRFIELD THIS EVENING CAUSING VSBY
RESTRICTIONS...WITH FOG KEEPING VSBYS LOW AFTERWARD UNTIL LATE
TONIGHT. EXPECT RAPID CLEARING AFTER 12Z ON TUE.
ELSEWHERE...THE REST OF THE REGION IS SHARING IN THE COLD AIR
DAMMING CONDITIONS. THIS MEANS GENERALLY IFR TO LIFR CIGS THROUGH
MOST OF TONIGHT. A WAVE OF SHOWERS WILL MOVE ACROSS THE AREA THIS
AFTERNOON INTO THIS EVENING RESTRICTING VSBYS. FOG WILL CONTINUE TO
THE RESTRICT VSBYS UNTIL AFTER A COLD FORNT MOVES THROUGH LATE
TONIGHT. EXPECT CLEARING EARLY TUE MORNING. THE ONLY AIRFIELD WHERE
THUNDER IS MENTIONED IS AT KAND AS WEDGE BOUNDARY WILL BE CLOSEST
THERE.
OUTLOOK...GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH THURSDAY.
CONFIDENCE TABLE...
19-01Z 01-07Z 07-13Z 13-19Z
KCLT MED 75% MED 74% MED 70% HIGH 84%
KGSP MED 74% MED 75% MED 61% HIGH 94%
KAVL HIGH 83% MED 71% MED 68% HIGH 100%
KHKY HIGH 84% MED 74% MED 69% HIGH 92%
KGMU MED 77% MED 72% MED 64% HIGH 94%
KAND MED 75% MED 77% MED 65% HIGH 94%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.FIRE WEATHER...
A WARM...DRY AND WINDY AIR MASS WILL MOVE IN TUE BEHIND A DEPARTING
COLD FRONT. MINIMUM RH VALUES WILL BE LESS THAN 25 PERCENT ACROSS
MUCH OF THE AREA WITH GUSTY WINDS DEVELOPING. ALTHOUGH FUEL MOISTURE
IS RELATIVELY HIGH AND PRECIP MOVES ACROSS THE AREA TONIGHT...NC
FOREST SERVICE IS CONCERNED ABOUT THE DRYING AND DEVELOPING WINDS.
THEREFORE...A FIRE DANGER STATEMENT WILL BE ISSUED FOR TUE. SC LAND
MANAGERS ARE NOT AS CONCERNED FOR THE UPSTATE AND NE GA FUEL
MOISTURE WAS NEAR 20 PERCENT MON AFTERNOON. THEREFORE...NO STATEMENT
FOR SC OR GA. BREEZY AND GUSTY CONDITIONS RETURN WED AFTERNOON WITH
ANOTHER DAY OF VERY LOW RH VALUES. FIRE DANGER STATEMENTS MAY BE
NEEDED THEN AS WELL.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...LG
SHORT TERM...RWH
LONG TERM...DEO
AVIATION...LG
FIRE WEATHER...RWH
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
202 PM EDT MON MAR 18 2013
.SYNOPSIS...
WEDGE OF HIGH PRESSURE WILL REMAIN IN PLACE THROUGH THIS EVENING.
WARM FRONT TO THE SOUTH FINALLY SLIDES NORTHEAST TONIGHT WHILE THE
COLD FRONT FOLLOWS CLOSELY BEHIND OVERNIGHT. HIGH PRESSURE WILL
MOVE IN BY TUESDAY AFTERNOON...WITH AN UPPER DISTURBANCE EXPECTED
TO AFFECT THE MOUNTAINS WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM EDT MONDAY...
12Z RNK SOUNDING SHOWED A 1.5 DEGREE C WARM NOSE ABV THE SFC...BUT
NO SNOW CRYSTAL GROWTH ZONE. WITH 14Z SFC TEMPS STILL BELOW
FREEZING ACROSS MANY MOUNTAIN LOCATIONS...LIGHT FREEZING DRIZZLE
IS STILL POSSIBLE THROUGH THE EARLY AFTERNOON...SO WINTER WEATHER
ADVISORY WILL CONTINUE. SFC WEDGE WILL PERSIST INTO THE
AFTERNOON...SO LOWERED HIGH TEMPS BY A FEW DEGREES
THE EXCEPTION WAS IN THE FAR WEST...WHERE CLEARING HAS TAKEN PLACE
ACROSS PORTIONS OF THE MOUNTAIN EMPIRE REGION. A FEW RUMBLES OF
THUNDER ARE NOT OUT OF THE QUESTION IN THIS REGION WHICH WILL
DESTABILIZE THIS AFTERNOON.
OTHERWISE...FOLLOWED THE 12Z RAP WITH TIMING OF PRECIP THIS
AFTERNOON.
THE FRONT MOVES IN TONIGHT AND WILL BE SEEING BEST THREAT OF RAIN
IN THE MTNS WITH MODELS SHOWING SOME JUMP IN THE HIGHER QPF ACROSS
THE PIEDMONT LEAVING THE MIDDLE PORTION OF THE CWA WITH LESS.
ALTHOUGH THIS IS A POSSIBILITY THINK POPS IN THE LIKELY TO
CATEGORICAL RANGE IS BEST. KEPT ISOLATED THUNDER IN THE FAR WEST
THIS EVENING OUTSIDE THE WEDGE.
THE COLDER AIR WILL BE SWINGING IN BEHIND THE FRONT LATE IN THE
HIGHER MOUNTAINS WITH SNOW SHOWERS POSSIBLE ON THE WRN SLOPES. DRY
SLOT ARRIVING WILL DRY THINGS OUT FAST BY DAWN EAST OF THE MTNS. LOW
RANGE FROM THE UPPER 20S HIGHER ELEVATIONS IN THE WEST WITH MOST
AREAS IN THE 30S...WHILE THE FAR EAST STAY STEADY IN THE LOWER
40S...WITH WEDGE HOLDING UNTIL COLD FROPA. TEMPS ACTUALLY MAY WARM
IN THE SMALL WINDOW BETWEEN WEDGE BREAKING AND FROPA AS COLDER AIR
WILL BE DELAYED.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
AS OF 415 AM EDT MONDAY...
A COLD FRONT WILL BE EXITING THE EASTERN PORTION OF THE BLACKSBURG
FORECAST AREA AROUND DAYBREAK TUESDAY...WITH ANY LINGERING SHOWERS
OVER EASTERN PIEDMONT COUNTIES TO END BY MID MORNING...FOLLOWED BY
CLEARING SKIES AS DOWNSLOPING INCREASES EAST OF THE BLUE RIDGE.
GOOD INSOLATION AND COMPRESSIONAL WARMING SHOULD OFFSET CONTRIBUTION
OF COLD ADVECTION ACROSS THE PIEDMONT THROUGH MUCH OF THE DAY...
SUPPORTING TEMPERATURES REACHING THE LOWER TO MID 60S. FURTHER
WEST...UPSLOPING CLOUDS AND ARRIVAL OF DEEPER COLDER AIR SHOULD
LIMIT DAYTIME HIGHS TO THE 30S ACROSS THE HIGHEST WEST FACING FLANKS
OF THE APPALACHIANS.
THE UPPER AIR PATTERN DOES NOT CHANGE MUCH THROUGH MID WEEK WITH
RIDGE IN THE WESTERN CONUS AND TROF IN THE EAST. THIS SUPPORTS A
TREND BACK TOWARD COLDER THAN NORMAL TEMPERATURES ACROSS OUR AREA.
NORTHWEST FLOW WILL PERSIST RIGHT ON INTO WEDNESDAY WITH 85H TEMPS
BLOW FREEZING. FOR THE MOST PART...THE FLOW IS DRY. THERE IS AN
UPPER LEVEL DISTURBANCE WHICH IS PROGGED TO COME THROUGH DURING THE
DAY WEDNESDAY. THIS FEATURE MAY BRING SNOW SHOWERS AND
FLURRIES...BUT MORE IMPORTANTLY A REINFORCING SHOT OF COLD AIR THAT
WILL SEND TEMPERATURES WELL BELOW NORMAL WEDNESDAY NIGHT INTO
THURSDAY AS 85H TEMPERATURES TEST M14 DEG C.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 400 PM EDT SUNDAY...
A BLOCKY HEMISPHERIC CIRCULATION IS ADVERTISED BY THE LONG RANGE
MODELS THROUGH NEXT WEEKEND...MARKED BY THREE STRONG POSITIVE HEIGHT
ANOMALIES. THE FIRST IS THROUGH THE BERING SEA WHILE THE SECOND AND
THIRD MERGE BETWEEN THE NORTH POLE AND THE DAVIS STRAIT.
TELECONNECTIONS FROM EACH AREA SUPPORT RIDGING JUST OFF THE WEST
COAST WITH BROAD TROUGHING FROM THE CENTRAL CONUS EASTWARD. THIS
VERY NEGATIVE AO PATTERN SUPPORTS BELOW NORMAL TEMPERATURES EAST OF
THE ROCKIES WITH THE POLAR FRONT ALONG THE GULF COAST.
WEATHER CHALLENGE DURING THIS TIME FRAME IS WHETHER ANY SORT OF
CYCLOGENESIS CAN TAKE PLACE ALONG THIS POLAR FRONT WHICH WILL BE
SITUATED SOUTH OF OUR FCST AREA...AND IF SO CAN ANY OF THIS ENERGY
GAIN ANY LATITUDE PER STRONG WESTERLIES WITHIN THE COLD TROUGH WHICH
WILL BE DIRECTLY OVERHEAD DURING THE PERIOD. FORECAST
SPREAD/UNCERTAINTY AND RUN-RUN CONTINUITY INCREASES SIGNIFICANTLY
HEADING INTO NEXT WEEKEND. RECENT ECMWF/ECMWF ENSEMBLES IN
PARTICULAR HAVE OFFERED MORE SUPPRESSED SOLUTIONS THAN RECENT
GFS/GEFS. THE GFS RUNS INSTEAD OFFER A DEEPER SERN US/MID-ATLC
COASTAL STORM. ENSEMBLES ARE MIXED/IN THE MIDDLE BUT OVERALL FAVOR
A SOLUTION WITH EMPHASIS OVER THE SRN/SERN US...THAT SOME SORT OF
SYSTEM WILL GET GENERATED. SINCE THERE IS NO SOLID CONSENSUS ON
HOW FAR NORTH THIS SYSTEM WILL TRACK...WILL ADVERTISE CHC POPS FOR
THE ENTIRE CWA...WITH FOCUS ON THE SUNDAY TIME FRAME...DAY 7. AS
LUCK WOULD HAVE IT...WINTER ISN`T OVER...SO PTYPE CHALLENGE WILL
ALSO COME INTO PLAY IF THE SYSTEM SPREADS ANY MOISTURE THIS FAR
NORTH.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AS OF 200 PM EDT MONDAY...
VERY POOR FLYING CONDITIONS WILL CONTINUE THROUGH THIS AFTERNOON
INTO EARLY TONIGHT. IFR/LIFR CEILINGS FROM STRATUS SHOULD PREVAIL
FOR ALL TAF SITES FOR THE REST OF TODAY...AS HIGH PRESSURE REMAINS
WEDGED AGAINST THE EASTERN SIDE OF THE BLUE RIDGE MOUNTAINS. A
COLD FRONT FROM THE OHIO RIVER VALLEY WILL BRING RAIN LATER THIS
EVENING...WHICH WILL EVENTUALLY ACT TO BREAK UP THE WEDGE TONIGHT.
DURING THIS FRONTAL PASSAGE...THERE IS HIGH CONFIDENCE THAT
SIGNIFICANT WIND SHEAR WILL BE PRESENT AT ALL TAF SITES...WITH
WINDS REACHING 40-45KT AT 2000 FEET. THE HIGHEST AMOUNTS OF WIND
SHEAR APPEAR IN THE MODEL SOUNDINGS FOR BLF AND LWB. AS THE WEDGE
GRADUALLY BREAKS FROM WEST TO EAST AFTER MIDNIGHT...THE LOW
STRATUS DECK SHOULD LIFT AND GIVE WAY TO VFR CONDITIONS BY
TUESDAY MORNING. CONFIDENCE IN THE TIMING OF WHEN THE CLOUDS WILL
BREAK REMAINS SOMEWHAT LOW. WINDS SHOULD INCREASE FROM THE WEST
WITH 20-30KT GUSTS AFTER DAYBREAK.
A BROAD UPPER LEVEL TROUGH WILL HOVER OVER THE NORTHEAST THROUGH
THE REST OF THIS WEEK. WITHIN THE FRINGE OF THIS TROUGH...A SMALL
CLIPPER COULD BRING UPSLOPE SNOW SHOWERS FOR BLF AND LWB DURING
WEDNESDAY AFTERNOON AND EVENING...BUT THE PIEDMONT WILL REMAIN
DRY. VFR CONDITIONS SHOULD PREVAIL AS WINDS TURN TO THE NORTHWEST
BUT REMAIN FAIRLY GUSTY DURING WEDNESDAY...WHICH SHOULD SUBSIDE BY
THURSDAY AS HIGH PRESSURE ARRIVES. THE MODELS DEPICT A DEVELOPING
LOW PRESSURE SYSTEM PASSING OVER THE SOUTHEAST BY FRIDAY AND
SATURDAY. IT IS TO EARLY TO TELL IF THE PRECIPITATION ASSOCIATED
WITH THIS SYSTEM WILL MAKE ANY IMPACT...AS THE MODELS ARE NOT IN
AGREEMENT ON IF IT COULD MISS THE AREA AND STAY TO THE SOUTH.
&&
.FIRE WEATHER...
AS OF 455 AM EDT MONDAY...
STRONG AND GUSTY WINDS FROM THE WEST WILL OVERSPREAD THE ENTIRE
REGION FOLLOWING THE PASSAGE OF A COLD ON TUESDAY. EAST OF THE
BLUE RIDGE...RELATIVE HUMIDITIES ARE EXPECTED TO FALL TO AROUND 20
PERCENT BY AFTERNOON...AND COUPLED WITH THE EXPECTED GUSTY
WINDS...MAY RESULT IN AN ELEVATED FIRE DANGER THREAT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR
VAZ018>020-023-024-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR
WVZ045.
&&
$$
SYNOPSIS...WP
NEAR TERM...PH
SHORT TERM...PM/WERT
LONG TERM...PM
AVIATION...PW
FIRE WEATHER...WERT
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
247 PM CDT MON MAR 18 2013
.SHORT TERM...
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A STRONG
SHORTWAVE MOVING ACROSS THE NORTHERN MISSISSIPPI VALLEY EARLY THIS
AFTERNOON. AHEAD OF THIS TROUGH...A SHORTWAVE IMPULSE LIFTED
NORTH OVER SOUTHEAST WISCONSIN THIS MORNING AND ACROSS NORTHEAST
WISCONSIN THIS AFTERNOON. THIS IMPULSE HAS GENERATED WIDESPREAD
1/4SM TO 1/2SM ACROSS THE FOX VALLEY AND LAKESHORE. THE MAIN BAND
OF SNOW RIGHT AHEAD OF THE MAIN SHORTWAVE IS MOVING ACROSS CENTRAL
WISCONSIN WHERE MODERATE TO HEAVY SNOW IS ALSO OCCURRING. JUST
LEARNED ABOUT HWY 13 FROM WISCONSIN RAPIDS TO THE DELLS THAT TRAVEL
BECOMING NOT ADVISED. THOUGHT ABOUT EXPANDING THE ADVISORY ACROSS
THE REST OF THE AREA...BUT WEBCAMS FROM OSHKOSH SHOW LITTLE IN THE
WAY OF ACCUMULATIONS ON THEIR ROADWAYS. ROAD TEMPERATURES ARE A
COUPLE DEGREES WARMER THERE THAN FARTHER NORTH AND WEST...WHICH
COULD EXPLAIN PART OF THE ACCUMULATION DIFFERENCES. WITH THE BACK
EDGE OF THE HEAVIER SNOW NOT TOO FAR AWAY FROM THE SOUTHERN FOX
VALLEY...WILL KEEP THEM OUT OF THE ADVISORY. ROADS ARE BECOMING
SNOW COVERED IF NOT ALREADY SNOW COVERED FARTHER NORTH...SO WILL LET
THE ADVISORY GO AS PLANNED. WILL BUMP UP ACCUMS A BIT OVER NE
WISCONSIN. THE EVENING CREW MAY BE ABLE TO CANCEL THE ADVISORY
EARLY IF THE STRENGTHENING WINDS THIS EVENING DO NOT CREATE BLOWING
AND DRIFTING SNOW OF ANY SIGNIFICANCE.
TONIGHT...SHORTWAVE TROUGH WILL SWING NE ACROSS NORTHEAST WISCONSIN
THIS EVENING...AS ITS PARENT TROUGH CLOSES OFF OVER THE UPPER
PENINSULA AND LAKE SUPERIOR. THE LATEST HRRR SUGGESTS MOST OF THE
SYNOPTIC SNOW WILL HAVE PEELED OUT BY THE START OF THE
PERIOD...EXCEPT OVER NORTH-CENTRAL WISCONSIN WHERE DEEP MOISTURE
WILL HANG IN PLACE. WHERE THE UPPER AND MID-LEVEL MOISTURE DOES
DEPART...SNOW WILL DIMINISH TO FLURRIES OR PATCHY LIGHT FREEZING
DRIZZLE. WILL KEEP FZDZ WORDING AS CHANCE SINCE OBS UPSTREAM SEEM
WIDELY SCT...BUT POTENTIAL WILL BE THERE FOR A FEW HOURS.
WRAP-AROUND SNOW THEN TO RETURN LATE IN THE EVENING AND OVERNIGHT.
PLENTY OF LOW VSBYS IN SNOW SHOWERS OVER SOUTHERN MINNESOTA AND
EASTERN SD...SO DO NOT FEEL COMFORTABLE GOING JUST FLURRIES THOUGH
ACCUMS SHOULD ONLY BE A TENTH TO A HALF INCH. MEANWHILE...ARCTIC AIR
WILL BE PUNCHING ACROSS CENTRAL AND SOUTHERN WISCONSIN DURING THE
EVENING...AND INTO NORTHEAST WISCONSIN OVERNIGHT. AS THIS COLDER
AIR ARRIVES...WEST WEST WILL BE STRENGTHENING AND BECOME QUITE
GUSTY. THE BEST PRESSURE RISES WILL SPLIT THE AREA TO THE NORTH AND
SOUTH...BUT SOME GUSTS COULD STILL REACH 35 MPH. UPSTREAM OFFICES
CANCELLED THEIR BLIZZARD WARNINGS EARLY SINCE VSBYS WERE NOT LOW
ENOUGH...SUGGESTING BLOWING AND DRIFTING MAY NOT HAVE BEEN AS BIG A
FACTOR AS PREVIOUSLY THOUGHT. EARLY INDICATIONS OF SNOWFALL RATIOS
SO FAR TODAY ARE AROUND 10-12 TO 1...SO SNOW MAY BE TOO WET TO RESTRICT
VSBYS DUE TO BLOWING. WILL KEEP THE END TIME OF THE ADVISORY AT
03Z.
MONDAY...THE UPPER LOW WILL SHIFT A LITTLE NE OVER LAKE SUPERIOR
TOMORROW...TAKING SOME OF THE DEEPER MOISTURE WITH IT. SHOULD STILL
BE ENOUGH MOISTURE AND CYCLONIC FLOW ALOFT FOR OCCASIONAL SNOW
SHOWERS AND FLURRIES DURING THE MORNING...THEN BECOMING CONFINED TO
N-C WISCONSIN DURING THE AFTERNOON. WEST TO NORTHWEST WINDS WILL
REMAIN GUSTY...AND AN ISOLATED GUST UP TO 40 MPH WILL BE POSSIBLE IN
THE OPEN AREAS. TEMPS MAINLY IN THE MIDDLE 20S.
.LONG TERM...
LITTLE CHANGE IN THE OVERALL...COLD...PATTERN FOR THE REGION
THROUGH THIS PERIOD. BROAD UPPER TROF OVER EASTERN TWO THIRDS OF
U.S. UPPER LOW TO SPIN OVER EASTERN LAKES INTO FRI...WHILE
MAIN STORM TRACK AND MOISTURE REMAINS TO OUR SOUTH. AT THE SURFACE
CANADIAN HIGH PRESSURE TO REMAIN OVER THE REGION.
TUE NIGHT INTO THU...
MAIN ISSUES LAKE EFFECT CHANCES AND CHANCE FOR SNOW SHOWERS ON
WED. PIECES OF ENERGY WILL CIRCULATE AROUND THE LOW THIS
PERIOD...BRINGING THREAT OF SNOW SHOWERS...FLURRIES. BEST CHANCE
TO BE ON WED AS UPPER TROF DROPS SOUTH OVER THE STATE.
HAVE TRIED TO ADD DEFINITION TO LAKE EFFECT CHANCES...WITH HIGHEST
CHANCES LATE TUE NIGHT INTO WEDNESDAY NIGHT AS HAVE SOME SYNOPTIC
LIFT AND MOISTURE. BY THE TIME THE WINDS BECOME MORE FAVORABLE
LATER WED NIGHT AND THU...SOUNDINGS SHOW LOWERING INVERSION
HEIGHTS AND DRYING WORKING IN.
THU NIGHT ONWARD...
EXTENDED MODELS STILL HAVING ISSUES LATER PERIODS...BRINGING LIGHT
QPF INTO THE REGION. STILL EXPECT ANY PACIFIC SYSTEM TO DIVE SE
AND PASS TOO FAR TO OUR SOUTH TO BRING ORGANIZED PCPN TO NE WI.
WITH HIGH PRESSURE AT SURFACE THROUGH PERIOD AND LIMITED MOISTURE
HAVE STAYED WITH DRY FORECAST. LLVL WINDS SHIFT TO NE FOR BRIEF
PERIOD SAT...WITH THOUGHTS OF LES OFF LAKE MICHIGAN. THOUGH AGAIN MOISTURE
AND INSTABILITY LIMITED. BELOW NORMAL TEMPERATURES EXPECTED TO
CONTINUE INTO THE LAST WEEK OF MARCH. HAVE AGAIN DROPPED FEW
DEGREES OFF GUIDANCE TEMPS FOR LATTER PERIODS.
&&
.AVIATION...
AREA OF MVFR CIGS IN NERN IA SHOULD OVERSPREAD THE REGION TDA.
THEN EXPECT SHARP DROP INTO IFR OR LIFR CATEGORY AS THE MAIN SNOW
BAND MOVES THROUGH.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 10 PM CDT THIS EVENING FOR WIZ005-
010>013-018>022-030-031-035>039-045-073-074.
&&
$$
MPC/TE