Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/20/13
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 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 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 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
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 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
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
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...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 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 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 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
800 PM EDT TUE MAR 19 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 415 PM EDT TUE MAR 19 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP CLOSED LO
CENTERED OVER ERN LK SUP DOWNSTREAM OF RDG ALONG THE W COAST. DEEP
CYC NW FLOW OF COLD AIR ARND THE SFC LO NEAR WAWA ONTARIO IS
DOMINATING THE CWA...CAUSING LES OVER MAINLY THE WRN ZNS EARLY THIS
AFTN AS -16C H85 TEMPS SHOWN AT INL AT 12Z MOVE OVER THE LAKE. WITH
SHARPENING PRES GRADIENT BTWN PRES RISE CENTER OVER NRN MN AND PRES
FALLS OVER SE ONTARIO TO THE E OF THE SFC LO...THE NW WINDS ARE
STRENGTHENING...WITH WIND GUSTS UP TO 40 MPH REPORTED CAUSING
EXTENSIVE BLSN. THE SN HAS TAPERED OFF OVER THE FAR W AND SCENTRAL
WITH THE ADVECTION OF DRIER AIR OBSVD IN MN AT 12Z/WELL DEPICTED ON
THE 12Z MPX RAOB AND DOWNSLOPE FLOW INTO THE SCENTRAL. PUBLIC
REPORTS INDICATE AS MUCH AS 18 INCHES OF SN HAS FALLEN OVER THE HIER
TERRAIN OF THE W. FARTHER UPSTREAM...ANOTHER SHRTWV IS DIGGING SEWD
THRU LK WINNIPEG.
MAIN FCST CONCERNS THRU WED REMAIN LES/WIND TRENDS AND GOING
HEADLINES AS CLOSED LO DRIFTS ONLY SLOWLY TO THE ENE THRU SE CANADA.
LATE TODAY/TNGT...OVERALL DEEP CYC NW FLOW ARND SLOWLY DEPARTING LO
IS PROGGED TO LINGER AND CAUSE PERSISTENT LES IN THE NW WIND SN
BELTS. THE LES INTENSITY OVER THE FAR W...ESPECIALLY WHERE THE FETCH
ACRS THE OPEN WATER IS SHORTER NEAR IWD...HAS DIMINISHED AS DRIER
AIR IN MN SLID EWD. THIS DRY AIR WL IMPACT MAINLY THE AREAS NEAR THE
WI BORDER. SO THE SCENTRAL SHOULD REMAIN DRY WITH DOWNSLOPING DRIER
FLOW. BUT LATER TNGT...SHRTWV NOW NEAR LK WINNIPEG IS FCST TO DIG
SEWD...CAUSING THE LLVL FLOW TO VEER A BIT AND BRING BACK A RETURN
OF DEEPER MSTR OVER THE ENTIRE CWA ON THE CYC SIDE OF ITS TRACK.
THESE TRENDS SHOULD CAUSE LES TO PICK UP AGAIN AT IWD FOLLOWING A
BREAK THIS EVNG. IN THE NW WIND SN BELTS E OF MQT...THE ARRIVAL OF
COLDER AIR WL LIKELY ENHANCE THE INTENSITY OF THE LES THRU THE NGT
WITH FVRBL WNW LLVL FLOW SHIFTING NW. ANOTHER FACTOR FAVORING HEAVY
SN IS FVRBL ALIGNMENT OF FCST UVV MAX WITHIN THE DGZ EVEN IF STRONG
WINDS THAT CAUSE A BREAK UP OF THE DENDRITES ACT TO REDUCE THE
SN/WATER RATIOS A BIT. BUT THESE STRONG WINDS WL CAUSE EXTENSIVE
BLSN/REDUCED VSBY ESPECIALLY NEAR LK SUP...EVEN WHEN THE LES IS NOT
FALLING HEAVILY.
WED...AS THE CLOSED LO SLOWLY DRIFTS TO THE E...CYC NW FLOW IS
PROGGED TO VEER SLOWLY TO THE NNW. WITH THE ARRIVAL OF SOMEWHAT
WARMER ATLANTIC AIR FM THE NE ARND INTENSE LO PER THE 12Z GFS AND
ESPECIALLY THE NAM...DEEP MSTR IS FCST TO LINGER. ALTHOUGH THE
WARMING WITH H85 TEMPS PROGGED TO RISE TOWARD -10C OVER FAR ERN LK
SUP MIGHT TEND TO REDUCE LES INTENSITY...THE ARRIVAL OF SOME LARGER
SCALE QVECTOR CNVGC/MAINTENANCE OF DEEPER MSTR ASSOCIATED SOME
ISENTROPIC ASCENT WL RETAIN A LK ENHANCED COMPONENT. ALTHOUGH THE
BEST CHC FOR CONTINUED DRY WX WL BE OVER THE SCENTRL...FCST SDNGS
INDICATE THE MSTR WL BE DEEP ENUF TO SUPPORT AT LEAST SCT -SHSN.
SOME OF THE GUIDANCE SUGGESTS SOME DRIER AIR MAY ARRIVE OVER THE W
ON WED AFTN... BUT SLOW MOTION OF THE CLOSED LO TO THE E FAVORS THE
MODELS THAT SHOW A SLOWER EWD PROGRESSION OF THIS DRYING.
GOING HEADLINES LOOK TO BE IN GOOD SHAPE AS LONG DURATION EVENT WL
ADD TO SN ACCUMS THAT HAVE ALREADY HIT WARNING TOTALS IN MOST AREAS
WHERE THESE HEADLINES HAVE BEEN IN EFFECT. EXPECT STORM TOTAL SN TO
REACH 24 INCHES OR MORE OVER THE HIER TERRAIN OF THE W.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 415 PM EDT TUE MAR 19 2013
LOOK FOR A SLOW AND STEADY RISE IN TEMPERATURES THROUGH THE PERIOD
AS WE SLOWLY LOSE THE INFLUENCE OF THE NEARBY 500MB TROUGH.
THE ELONGATED 500MB TROUGH WILL EXTEND FROM JUST NE OF MAINE TO
LOWER MI...AND SOUTHERN UPPER PORTIONS OF UPPER MI AT 00Z
THURSDAY...WITH A SIZABLE RIDGE STRETCHING ACROSS WYOMING AND THE
WESTERN DAKOTAS UP THROUGH SASKATCHEWAN.
WHILE THE 500MB RIDGE WILL PUSH INTO WESTERN UPPER MI/LAKE SUPERIOR
FRIDAY...IT WILL TAKE UNTIL FRIDAY NIGHT UNTIL THE NEARLY STEADY
STATE LOW OVER THE EAST PUSHES OFFSHORE. THE 19/00Z RUNS OF THE
ECMWF AND CANADIAN HOLD ONTO THE TROUGH ACROSS EASTERN UPPER MI A
BIT LONGER THAN THE GFS /BY ROUGHLY 6HRS/. THE SFC TROUGH WILL
LIKELY LINGER ACROSS EASTERN MICHIGAN THROUGH 12Z FRIDAY. THE RESULT
WILL BE CONTINUED LAKE EFFECT SNOW SHOWERS FOR NORTHERLY-NNW WIND
FAVORED LOCATIONS NEAR LAKE SUPERIOR. 850MB TEMPS WILL MODERATE FROM
THE -12 TO -15C AT 00Z THURSDAY TO AROUND -8C BY DAYBREAK FRIDAY.
EXPECT QUICKLY DIMINISHING LAKE EFFECT SNOW SHOWERS AFTER THURSDAY
AFTERNOON...WITH LOWERING INVERSION HEIGHTS
500MB RIDGING WILL BE THE RULE FRIDAY NIGHT THROUGH AT LEAST
SATURDAY NIGHT.
LOOK FOR A CLUSTERED AREA OF LOW PRESSURE CENTERED NEAR MONTANA AT
00Z SATURDAY WILL DIVIDE FRIDAY NIGHT...WITH THE NORTHERN LOW
SPINNING IN PLACE...AND THE SOUTHERN EXTENT OF THE TROUGH DIVING
ACROSS TEXAS AND OKLAHOMA BY LATE SATURDAY AFTERNOON/SATURDAY NIGHT.
THE 00Z RUNS OF THE GFS AND ECMWF WERE FAIRLY CONSISTENT WITH THE
TRACK OF THE SOUTHERN TROUGH...MOVING IT OVER KENTUCKY AND WEST
VIRGINIA BY DAYBREAK MONDAY...WITH THE RIDGE WEAKENING BUT STILL
REMAINING OVER LAKE SUPERIOR AND UPPER MICHIGAN THROUGH AT LEAST
SUNDAY NIGHT. THE 12Z GFS CAME IN WITH THE 500MB LOW SHIFTED APPROX
250MI TO THE NORTHWEST OF THE 00Z RUN TRACK...WHICH WOULD BRING IT
ACROSS LOWER MI AT 00Z TUESDAY. THIS WOULD RESULT IN STRONGER WINDS
FOR CENTRAL AND EASTERN AREAS...AS WELL AS UPSLOPE LES NORTH CENTRAL
WITH SYNOPTIC SNOW HUGGING THE EASTERN COUNTIES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 752 PM EDT TUE MAR 19 2013
WITH A COLD CYCLONIC NW FLOW CONTINUING AROUND LOW PRES DEPARTING
SLOWLY THROUGH SE ONTARIO THIS FCST PERIOD...EXPECT SHSN TO IMPACT CMX/
IWD...WITH IFR/LIFR CONDITIONS PREDOMINATING. THE WORST CONDITIONS
TO VLIFR ARE MOST LIKELY AT THE MORE EXPOSED CMX LOCATION THROUGH
THIS EVNG WITH DEEPER MOISTURE AND STRONGER WINDS.
A TEMPORARY PERIOD OF VFR CONDITIONS AT IWD WITH DRIER AIR MOVING
ESE FROM MN IS EXPECTED TO GIVE WAY TO HEAVIER AND MORE PERSISTENT
LES LATER THIS EVENING AS WINDS VEER NW. AT SAW...DOWNSLOPING NW
WINDS SHOULD RESULT IN MAINLY MVFR CONDITIONS THRU THE FCST PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 415 PM EDT TUE MAR 19 2013
EXPECT NW GALES/HEAVY FREEZING SPRAY TO LINGER THRU AT LEAST WED
MORNING AS DEEP LO PRES OVER SE ONTARIO EDGES SLOWLY TO THE E AND A
COLD...GUSTY NW WIND CONTINUES. WINDS/FREEZING SPRAY ARE LIKELY TO
DIMINISH OVER THE W WED AFTERNOON FARTHER FROM THE SLOWLY RETREATING
LO.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY FOR
MIZ001>004-009-084.
WINTER STORM WARNING UNTIL 8 AM EDT THURSDAY FOR MIZ006-007-085.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 8 PM EDT /7 PM CDT/ WEDNESDAY
FOR LSZ162-240>245-248>251-263>267.
GALE WARNING UNTIL 2 PM EDT /1 PM CDT/ WEDNESDAY FOR LSZ162-
243>245-249>251-263>267.
GALE WARNING UNTIL 6 AM EDT WEDNESDAY FOR LSZ248.
GALE WARNING UNTIL 11 PM EDT THIS EVENING FOR LSZ246-247.
GALE WARNING UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR
LSZ240>242.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...JLB
MARINE...KC
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 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 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 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 HASTINGS NE
647 PM CDT TUE MAR 19 2013
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 357 PM CDT TUE MAR 19 2013
MORNING UPPER AIR ANALYSIS INDICATES LONGWAVE TROUGHING OVER THE
EASTERN-HALF OF THE CONUS WITH RIDGING OVER THE WEST.
NORTHWESTERLY MID AND UPPER LEVEL FLOW PERSISTS OVER THE CENTRAL
PLAINS AS A RESULT. TROPOSPHERIC FLOW OVER OUR AREA MAXES OUT AT
AROUND 120KTS PER 12Z SOUNDING DATA FROM KOAX AND KLBF. WATER
VAPOR IMAGERY ALSO INDICATES A SUBTLE MID LEVEL PERTURBATION OVER
EASTERN MONTANA...MOVING TO THE SOUTHEAST. AT THE SURFACE A TROUGH
IS NOTED EXTENDING FROM WESTERN IOWA INTO SOUTHEASTERN NEBRASKA
AND KANSAS...WITH A COLD FRONT ALSO NOTED OVER THE DAKOTAS. THE
LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE NORTHWEST AS
A RESULT.
PROXIMITY SOUNDINGS FROM ACROSS CWA...PER RAP ANALYSIS AND LAPS
DATA...SUGGEST VERY STEEP LOW TO MID LEVEL LAPSE RATES ARE IN
PLACE...WITH NEARLY DRY ADIABATIC LAPSE RATES NOTED FROM THE
SURFACE TO BETWEEN 750MB AND 700MB ACROSS MUCH OF OUR AREA. AS A
RESULT...MODEST SBCAPE VALUES ON THE ORDER OF 100-200J/KG ARE IN
PLACE ACROSS MUCH OF THE CWA. AN EXPANDING CU FIELD AS BEEN NOTED
ON SATELLITE IMAGERY ACROSS MUCH OF NEBRASKA AS A RESULT...WITH
KUEX AND KLNX SUGGESTING ELEVATED PRECIPITATION HAS RESULTED. SOME
OF THIS PRECIPITATION IS MAKING IT TO THE SURFACE IN THE FORM OF
RAIN AND GRAUPEL...BOTH OF WHICH WAS OBSERVED AT THE OFFICE
BETWEEN 19Z AND 20Z. IN ADDITION...A COUPLE OF CG STRIKES HAVE
BEEN DETECTED FROM HALL COUNTY INTO BUFFALO COUNTY WITH SOME OF
THE MORE INTENSE CELLS. WITH ANY OMEGA STILL REMAINING WELL
NORTHWEST OF OUR AREA OVER THE NORTHERN HIGH PLAINS...IN THE
VICINITY OF THE AFOREMENTIONED MID LEVEL PERTURBATION...IT APPEARS
THE CURRENT ACTIVITY IS BEING PROMOTED BY DIABATIC HEATING ALONE.
SO...THIS ACTIVITY SHOULD CONTINUE THROUGH 22Z OR 23Z BEFORE THE
LOSS OF DIABATIC HEATING IS REALIZED LATER THIS EVENING. WENT
AHEAD WITH ISOLATED RAIN AND SNOW SHOWERS...ALONG WITH OCCASIONAL
LIGHTNING...IN THE FORECAST THROUGH 00Z.
THE SAME PROXIMITY SOUNDINGS FROM ACROSS THE CWA ALSO INDICATE
VERY DRY LOWER TROPOSPHERIC AIR IN PLACE ACROSS THE AREA...THUS
RESULTING IN DEEP INVERTED-V SOUNDINGS ACROSS THE ENTIRE CWA.
GIVEN THE ABUNDANT VIRGA NOTED HERE AT THE OFFICE...ALONG WITH THE
UPDRAFT STRENGTH NOTED FROM KUEX THROUGH THE PAST HOUR...FELT IT
PRUDENT TO INTRODUCE BRIEF WIND GUSTS TO AROUND 50 MPH IN THE HWO
THROUGH THIS EVENING.
THE MID LEVEL PERTURBATION...CURRENTLY OVER THE NORTHERN HIGH
PLAINS...IS EXPECTED TO SWEEP OVER OUR AREA TONIGHT. ANY OMEGA IN
ASSOCIATION WITH THIS FEATURE IS EXPECTED TO REMAIN WEAK AND WITH
NO OTHER SIGNIFICANT SOURCE OF LIFT DURING THE SHORT TERM
FORECAST PERIOD...DRY CONDITIONS ARE FORECAST TONIGHT INTO
TOMORROW.
THE PASSAGE OF THE MID LEVEL PERTURBATION WILL ALSO HELP PUSH THE
LOW LEVEL BAROCLINIC ZONE...CURRENTLY OVER THE DAKOTAS...ACROSS
OUR AREA TONIGHT. THIS WILL IN TURN ALLOW A COOLER AIRMASS INTO
OUR REGION THUS RESULTING IN SOMEWHAT COOLER WEDNESDAY MORNING
LOWS WHEN COMPARED TO TUESDAY MORNING. OVERNIGHT LOWS IN THE TEENS
AND 20S ARE CURRENTLY FORECAST FOR TONIGHT AS A RESULT. THE
SURFACE RIDGE IS THEN EXPECTED TO PUSH OFF TO OUR EAST DURING THE
DAY WEDNESDAY...WITH LOW LEVEL RETURN FLOW AND RESULTANT WARM AIR
ADVECTION ALLOWING WEDNESDAY AFTERNOON HIGHS TO CLIMB INTO THE 40S
AND LOWER 50S FOR MOST LOCATIONS ACROSS THE AREA.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 357 PM CDT TUE MAR 19 2013
WEDNESDAY NIGHT THROUGH TUESDAY. PRIMARY FORECAST CONCERN REVOLVES
AROUND A MESSY PATTERN WITH MULTIPLE PRECIPITATION CHANCES
DURING THE LATE WORK WEEK/WEEKEND TIME FRAME.
STILL EXPECTING THE START OF THE LONG TERM PERIOD TO BE DRY...WITH
MODELS IN GOOD AGREEMENT SHOWING NORTHWESTERLY FLOW SET UP IN THE
UPPER LEVELS ACROSS THE REGION WEDNESDAY EVENING INTO THE
OVERNIGHT HOURS...WITH AN ELONGATED LOW PRESSURE SYSTEM SPREAD
FROM THE NORTHEASTERN CONUS THROUGH THE GREAT LAKES...AND
SHORTWAVE RIDGING OVER THE ROCKIES AHEAD OF ANOTHER TROUGH ALONG
THE WEST COAST. AT THE SURFACE...THE CWA SITS BETWEEN A RIDGE OF
HIGH PRESSURE ALONG/JUST EAST OF THE MISSOURI RIVER...AND LOW
PRESSURE EXTENDING FROM THE NORTHERN ROCKIES DOWN INTO SERN
COLORADO...BRINGING SOUTHEASTERLY WINDS TO THE AREA.
AS WE GET INTO EARLY THURSDAY MORNING...STILL SEEING THE MAIN
MID/UPPER LEVEL TROUGH/LOW PRESSURE SYSTEM IN PLACE TO THE
WEST...WITH THE FIRST OF A COUPLE OF DISTURBANCES EJECTED OUT
AHEAD OF IT BEGINNING TO AFFECT THE REGION. MAIN CHANGE WITH THE
MODELS HAS BEEN WITH MORE AGREEMENT BACKING OFF THE COVERAGE OF
PRECIPITATION ACROSS THE CWA...THERE IS PLENTY OF DRIER AIR TO
OVERCOME...AND BETTER CHANCES LOOK TO BE ACROSS EASTERN PORTIONS
OF THE CWA DURING THE DAY ON THURSDAY AS THE MID LEVEL TROUGH AXIS
SWINGS THROUGH AND FRONTOGENETICAL LIFT INCREASES. REALLY TAPERED
BACK POPS...ESP ACROSS THE WRN THIRD OF THE CWA...IT IS POSSIBLE
AFTER 12Z THURSDAY SOME WESTERN LOCATIONS MAY NOT SEE MUCH OF
ANYTHING. DIDNT WANT TO COMPLETELY PULL POPS YET...WANT TO SEE
SOME CONSISTENCY WITH THIS TREND FIRST. DECIDED TO HOLD ON TO THE
MIXED PRECIPITATION ACROSS THE SWRN CWA DURING THE EARLY/MID
MORNING HOURS ON THURSDAY...BUT CONFIDENCE IS NOT HIGH IN IT
OCCURRING. IF PRECIPITATION OCCURS AT ALL IN THAT PART OF THE
CWA...CANT COMPLETELY RULE OUT A BRIEF PERIOD OF MORE OF A
MIX...BUT NOT EXPECTING IT TO AMOUNT TO MUCH.
BUMPED UP HIGH TEMPERATURES ON THURSDAY ONCE AGAIN WITH MODELS
TRENDING TOWARD THE POTENTIAL FOR DRIER CONDITIONS DURING THE
AFTERNOON HOURS...SWRN LOCATIONS COULD REACH INTO THE LOWER/MID
40S. THINK THE NORTHEAST HALF WILL STRUGGLE WITH PRECIP/MORE CLOUD
COVER LINGERING LONGER INTO THE DAY.
SHOULD SEE A LULL IN THE ACTIVITY LATER IN THE DAY THURSDAY AND
INTO THURSDAY EVENING...BUT IT WILL BE A BRIEF BREAK WITH THE
NEXT DISTURBANCE TAKING AIM ON THE REGION. MODELS SHOWING THE MAIN
TROUGH OVER THE NORTHWESTERN CONUS/NRN ROCKIES TRYING TO EVOLVE
INTO A CLOSED CIRCULATION AS ANOTHER 110+KT UPPER LEVEL JET STREAK
DIGS INTO THE WEST COAST. ANOTHER SHORTWAVE DISTURBANCE EJECTED
OUT FROM THIS SYSTEM LOOKS TO BRING ANOTHER CHANCE FOR
PRECIPITATION TO THE CWA. THERE CONTINUE TO BE SOME SLIGHT
DIFFERENCES...BUT MODELS HAVE TRENDED TOWARD MORE AGREEMENT
SHOWING THE TIMING COMING DURING THURSDAY NIGHT INTO THE FIRST
HALF OF THE DAY ON FRIDAY. THINKING THE PRIMARY PRECIPITATION TYPE
FOR MOST WILL BE SNOW...BUT CANT RULE OUT MORE OF A RA/SN
MIX...MAINLY ACROSS THE SOUTHERN CWA. LIKE THURSDAY...TRENDED BACK
POPS ON FRIDAY...THE BETTER CHANCES COME DURING THE 00-12Z FRIDAY
TIME FRAME...WITH VERY LITTLE IN THE WAY OF POPS DURING THE
AFTERNOON HOURS. BECAUSE OF THIS...ALSO BUMPED UP HIGHS ON
FRIDAY...WITH MID 30S IN THE NORTHEAST TO LOWER/MID 40S IN THE
SOUTHWEST.
FRIDAY AFTERNOON AND INTO THE OVERNIGHT HOURS WILL BRING ANOTHER
LULL IN THE ACTIVITY...BEFORE FOCUS QUICKLY TURNS TO A STRONGER
SYSTEM WHICH WILL BRING THE POTENTIAL FOR MORE WIDESPREAD
ACCUMULATING SNOWFALL TO THE REGION. BY EARLY SATURDAY
MORNING...MODELS HAVE STARTED TO COME INTO BETTER AGREEMENT
SHOWING THE DEVELOPMENT OF A LOW PRESSURE SYSTEM OVER THE BORDER
OF MONTANA/CANADA...WHILE A PIECE OF ENERGY SWINGING FURTHER SOUTH
INTO THE ROCKIES DOES THE SAME...AND ITS THIS SOUTHERN ONE WHICH
WILL AFFECT OUR CWA. LIFT WILL BEGIN TO INCREASE ACROSS THE CWA
OUT AHEAD OF THIS SYSTEM LATE FRIDAY NIGHT...ALREADY BRINGING
PRECIPITATION CHANCES TO MAINLY THE WESTERN HALF OF THE CWA.
THROUGH THE DAYTIME HOURS ON SATURDAY THIS UPPER LEVEL LOW WILL
CONTINUE TO PUSH EAST...BRINGING INCREASING PRECIPITATION
CHANCES...AND BY 00Z LOOKS TO BE OVER CENTRAL/ERN PORTIONS OF
COLORADO. THERE ARE SOME TIMING DIFFERENCES...THE ECMWF/GFS ARE IN
PRETTY GOOD AGREEMENT...WITH THE GEM A TOUCH SLOWER. WHAT HAPPENS
THEN THROUGH THE OVERNIGHT HOURS SATURDAY NIGHT AND THEN INTO
SUNDAY IS GOING TO DEPEND ULTIMATELY ON THE PATH/TIMING OF THIS
UPPER LEVEL LOW. THE TIMING/PATH DIFFERENCES BETWEEN THE MODELS
CONTINUE...BUT THEY ALL BRING MORE WIDESPREAD SNOWFALL
ACCUMULATION. THIS IS ESPECIALLY TRUE WITH THE GEM...WHICH IS THE
SLOWEST AND MOST WOUND UP SYSTEM COMPARED TO THE ECMWF/GFS...BUT
ITS PATH IS SOMEWHAT IN BETWEEN THE TWO...TAKING IT MORE THROUGH
CENTRAL KS. THERE ARE PLENTY OF THINGS TO WORK OUT IN THE COMING
DAYS...AND EXPECT MODEL CHANGES...BUT THOSE WITH WEEKEND PLANS
NEED TO KEEP AN EYE ON THIS SYSTEM. AS FAR AS TEMPERATURES
GO...EXPECTING HIGHS TO STRUGGLE TO GET OUT OF THE MID 30S BOTH
SATURDAY AND SUNDAY.
LOOKING AHEAD TO MONDAY AND TUESDAY...KEPT THE FORECAST DRY...BUT
THE MESSY UPPER LEVEL PATTERN REMAINS. MODELS KEEP THE REGION
UNDER THE INFLUENCE OF A BROAD TROUGH...WITH PIECES OF
ENERGY/LOW PRESSURE SYSTEMS ROTATING AROUND EACH OTHER. IN THIS
PATTERN...CERTAINLY WOULNDT BE SEEING MUCH/IF ANY WARM UP...WITH
HIGHS REMAINING IN THE 30S /AVERAGE FOR THIS TIME OF YEAR IS THE
LOWER 50S/...AND ITS NOT OUT OF THE REALM OF POSSIBILITY THAT SOME
OF THIS ENERGY COULD BRING ANOTHER CHANCE FOR PRECIPITATION...ESP
TUESDAY. BUT AT THIS POINT...WITH THERE ALREADY ENOUGH UNCERTAINTY
THROUGH THE WEEKEND...WASNT CONFIDENT ENOUGH TO GO WITH ANY POPS
FOR DAY 7.
&&
.AVIATION...(FOR THE 00Z TAF THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 647 PM CDT TUE MAR 19 2013
VFR CONDITIONS ARE EXPECTED AT KGRI FOR THE NEXT 24 HOURS. SKIES
WILL CONTINUE TO CLEAR ACROSS THE TERMINAL THIS EVENING...WITH MID
LEVEL CLOUDS DISSIPATING AND CLEAR SKIES PREVAILING BY 20/10Z.
NORTHWESTERLY WINDS WILL CONTINUE TO DIMINISH AROUND
SUNSET...SLOWLY SHIFTING FROM THE NORTHWEST THIS EVENING TO THE
SOUTHEAST BY LATE TOMORROW AFTERNOON...IN RESPONSE TO AN AREA OF
SURFACE HIGH PRESSURE SHIFTING EAST INTO THE MISSOURI RIVER VALLEY
TOMORROW AFTERNOON.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...BRYANT
LONG TERM...ADO
AVIATION...ROSSI
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 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 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 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
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 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 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
1042 PM CDT TUE MAR 19 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A VERTICALLY
STACKED LOW PRESSURE SYSTEM STALLED OVER FAR EASTERN LAKE SUPERIOR
THIS AFTERNOON. CLEARING SKIES ARE GRADUALLY OCCURRING FROM SW TO
NE ACROSS THE STATE AND HAS NOW REACHED FROM ABOUT RHINELANDER TO
MANITOWOC. STILL GETTING AN OCCASIONAL LIGHT SNOW OR FLURRY REPORT
OVER N-C WISCONSIN...AND VSBYS ARE ALSO OCCASIONALLY FALLING TO
AROUND 4SM DUE TO BLOWING SNOW. WIND GUSTS HAVE BEHAVED THEMSELVES
SO FAR THIS AFTERNOON...AS PEAK GUSTS WITHIN THE FORECAST AREA HAVE
REMAINED BELOW 35 KTS. SHEBOYGAN SEEMS TO BE THE LONE SPOT WHERE
GUSTS HAVE REACHED GREATER THAN 40 MPH. AS THE UPPER LOW REMAINS
STATIONARY TONIGHT AND DROPS SOUTH TOMORROW...SNOW CHANCES AND CLOUD
COVER ARE THE MAIN FORECAST CONCERNS.
TONIGHT...UPPER LEVEL LOW PRESSURE TO SIT AND SPIN OVER EASTERN LAKE
SUPERIOR TONIGHT. INCOMING LOW LEVEL DRYING FROM THE SW HAS
POTENTIAL TO REACH THE U.P. BORDER WHERE WNW WINDS SHOULD KEEP
CLOUDS ALONG AND NORTH OF THE BORDER THROUGH THE EVENING. AS A
RESULT...WENT MUCH MORE OPTIMISTIC WITH CLOUD COVER THIS EVENING
WITH MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS ACROSS THE MAJORITY OF
THE FORECAST AREA EXPECT FOR NEAR THE BORDER. AFTER MIDNIGHT...MID
AND UPPER MOISTURE PIVOT AROUND THE UPPER LOW AND BACK SOUTH ACROSS
NORTHERN WISCONSIN. THINK CLOUDS WILL INCREASE ONCE AGAIN WITH SNOW
SHOWERS RETURNING TO NORTH-CENTRAL WISCONSIN. NOT EXPECTING MUCH
MORE THAN A HALF INCH ACCUM THOUGH. COLD ADVECTION WILL OCCUR
THROUGH THE NIGHT AND LOWS UPSTREAM WERE IN THE SINGLE DIGITS ABOVE
ZERO OVER EASTERN MINNESOTA. THAT SOUNDS ABOUT RIGHT FOR LOWS
TONIGHT...SINCE BL WINDS LOOK TO BE TOO STRONG FOR DECOUPLING. SO
RAISED LOWS A DEGREE OR TWO.
WEDNESDAY...MOISTURE WILL CONTINUE TO SURGE SOUTH ACROSS CENTRAL AND
SOUTHERN WISCONSIN WEDNESDAY MORNING. WITH STEEPENING LOW LEVEL
LAPSE RATES...SKIES SHOULD CLOUD UP PRETTY QUICKLY BY MID TO LATE
MORNING. LIGHT SNOW SHOWERS AND FLURRIES SHOULD BE SPREADING FROM
NORTH TO SOUTH FROM LATE MORNING THROUGH THE AFTERNOON HOURS...WHEN
THE SHORTWAVE THAT CREATED THE SNOW YESTERDAY...ROTATES AROUND THE
BACKSIDE OF THE UPPER LOW AND DROPS SOUTH ACROSS THE STATE. LOW
LEVEL WINDS DO VEER TO THE NW TOMORROW AFTERNOON WHICH WILL BE
BETTER FOR LAKE ENHANCEMENT. SO WILL GIVE POPS A BOOST TOMORROW
EVERYWHERE. POTENTIAL WILL BE THERE FOR A HALF TO AN INCH OF NEW
SNOW ACROSS THE AREA.
.LONG TERM...
SOME HINTS THAT CURRENT COLD PATTERN MAY WANE TOWARDS END OF MODEL
RUN AS BLOCKY PATTERN BREAKS DOWN...THOUGH BEFORE THAT DRY WITH
BELOW NORMAL TEMPERATURES CONTINUE.
WED NIGHT THROUGH THU...INFLUENCE OF UPPER LOW OVER THE EASTERN
LAKES TO LESSEN WITH RIDGE MOVING IN. THOUGH WITH CYCLONIC FLOW
HAVE STAYED WITH HIGHER CLOUD COVER ON WED NIGHT...PARTLY CLOUDY
BY THU. WINDS EXPECTED TO BE LIGHTER BUT NOT DECOUPLE
TOTALLY...ESPECIALLY EAST. WITH THESE THOUGHTS...RAISED TEMPS A
BIT WITH COLDEST SPOT EXPECTED OVER CENTRAL WHERE WINDS WILL BE LIGHTEST.
WITH WINDS SHIFTING NORTH AFTER PASSAGE OF SHORT WAVE EXPECT LAKE
EFFECT SHOWERS TO CONTINUE...THOUGH AS RIDGE BUILDS IN INVERSION
HEIGHTS LOWER AND DRIER AIR WORKS IN. HAVE TRENDED DOWN ON
POPS...ESPECIALLY AFTER MIDNIGHT WED NIGHT.
THU NIGHT ONWARD...AIR MASS TRENDING TO MODERATE WITH
TIME...THOUGH NO APPEARANCE OF ANY SIG WAA. WILL SLOWLY BRING
TEMPS UP...THOUGH STILL HAVE HIGHS SOME 5 TO 10 DEGREES BELOW
NORMS. PACIFIC SYSTEM TO DROP SE INTO SOUTHERN PLAINS...THEN LIFT
OUT INTO THE OHIO VALLEY MONDAY TIMEFRAME. SOME DIFFERENCES IN
THE MODELS WITH GFS STRONGER AND FURTHER NORTH BRINGING QPF NORTH
INTO THE REGION. HAVE DOWN PLAYED THAT SCENARIO IN GRIDS...AS GFS
LACK CONSISTENCY IN LATTER PERIODS. HAVE TRENDED TOWARDS ECENS.
CANADIAN HIGH PRESSURE TO DOMINATE AT THE SURFACE WITH WINDS
SHIFTING NE SAT INTO TUE. HAVE BROUGHT CLOUDS UP SLIGHTLY IN THE
EAST WITH FLOW OFF LAKE...THOUGH WITH LIMITED INSTABILITY WILL
STAY DRY.
&&
.AVIATION...2000 TO 3000 FT CIGS AND A FEW SNOW FLURRIES NEAR THE
MICHIGAN BORDER WILL TRY TO MOVE SOUTH A LITTLE BUT MOST PLACES
WILL BE CLEAR TONIGHT. COLD AIR ALOFT WILL GENERATE MVFR CIGS AND
SNOW SHOWERS WEDNESDAY AS AN UPPER LEVEL LOW MOVES SOUTH TOWARDS
THE REGION.
RDM
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
719 PM CDT TUE MAR 19 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A VERTICALLY
STACKED LOW PRESSURE SYSTEM STALLED OVER FAR EASTERN LAKE SUPERIOR
THIS AFTERNOON. CLEARING SKIES ARE GRADUALLY OCCURRING FROM SW TO
NE ACROSS THE STATE AND HAS NOW REACHED FROM ABOUT RHINELANDER TO
MANITOWOC. STILL GETTING AN OCCASIONAL LIGHT SNOW OR FLURRY REPORT
OVER N-C WISCONSIN...AND VSBYS ARE ALSO OCCASIONALLY FALLING TO
AROUND 4SM DUE TO BLOWING SNOW. WIND GUSTS HAVE BEHAVED THEMSELVES
SO FAR THIS AFTERNOON...AS PEAK GUSTS WITHIN THE FORECAST AREA HAVE
REMAINED BELOW 35 KTS. SHEBOYGAN SEEMS TO BE THE LONE SPOT WHERE
GUSTS HAVE REACHED GREATER THAN 40 MPH. AS THE UPPER LOW REMAINS
STATIONARY TONIGHT AND DROPS SOUTH TOMORROW...SNOW CHANCES AND CLOUD
COVER ARE THE MAIN FORECAST CONCERNS.
TONIGHT...UPPER LEVEL LOW PRESSURE TO SIT AND SPIN OVER EASTERN LAKE
SUPERIOR TONIGHT. INCOMING LOW LEVEL DRYING FROM THE SW HAS
POTENTIAL TO REACH THE U.P. BORDER WHERE WNW WINDS SHOULD KEEP
CLOUDS ALONG AND NORTH OF THE BORDER THROUGH THE EVENING. AS A
RESULT...WENT MUCH MORE OPTIMISTIC WITH CLOUD COVER THIS EVENING
WITH MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS ACROSS THE MAJORITY OF
THE FORECAST AREA EXPECT FOR NEAR THE BORDER. AFTER MIDNIGHT...MID
AND UPPER MOISTURE PIVOT AROUND THE UPPER LOW AND BACK SOUTH ACROSS
NORTHERN WISCONSIN. THINK CLOUDS WILL INCREASE ONCE AGAIN WITH SNOW
SHOWERS RETURNING TO NORTH-CENTRAL WISCONSIN. NOT EXPECTING MUCH
MORE THAN A HALF INCH ACCUM THOUGH. COLD ADVECTION WILL OCCUR
THROUGH THE NIGHT AND LOWS UPSTREAM WERE IN THE SINGLE DIGITS ABOVE
ZERO OVER EASTERN MINNESOTA. THAT SOUNDS ABOUT RIGHT FOR LOWS
TONIGHT...SINCE BL WINDS LOOK TO BE TOO STRONG FOR DECOUPLING. SO
RAISED LOWS A DEGREE OR TWO.
WEDNESDAY...MOISTURE WILL CONTINUE TO SURGE SOUTH ACROSS CENTRAL AND
SOUTHERN WISCONSIN WEDNESDAY MORNING. WITH STEEPENING LOW LEVEL
LAPSE RATES...SKIES SHOULD CLOUD UP PRETTY QUICKLY BY MID TO LATE
MORNING. LIGHT SNOW SHOWERS AND FLURRIES SHOULD BE SPREADING FROM
NORTH TO SOUTH FROM LATE MORNING THROUGH THE AFTERNOON HOURS...WHEN
THE SHORTWAVE THAT CREATED THE SNOW YESTERDAY...ROTATES AROUND THE
BACKSIDE OF THE UPPER LOW AND DROPS SOUTH ACROSS THE STATE. LOW
LEVEL WINDS DO VEER TO THE NW TOMORROW AFTERNOON WHICH WILL BE
BETTER FOR LAKE ENHANCEMENT. SO WILL GIVE POPS A BOOST TOMORROW
EVERYWHERE. POTENTIAL WILL BE THERE FOR A HALF TO AN INCH OF NEW
SNOW ACROSS THE AREA.
.LONG TERM...
SOME HINTS THAT CURRENT COLD PATTERN MAY WANE TOWARDS END OF MODEL
RUN AS BLOCKY PATTERN BREAKS DOWN...THOUGH BEFORE THAT DRY WITH
BELOW NORMAL TEMPERATURES CONTINUE.
WED NIGHT THROUGH THU...INFLUENCE OF UPPER LOW OVER THE EASTERN
LAKES TO LESSEN WITH RIDGE MOVING IN. THOUGH WITH CYCLONIC FLOW
HAVE STAYED WITH HIGHER CLOUD COVER ON WED NIGHT...PARTLY CLOUDY
BY THU. WINDS EXPECTED TO BE LIGHTER BUT NOT DECOUPLE
TOTALLY...ESPECIALLY EAST. WITH THESE THOUGHTS...RAISED TEMPS A
BIT WITH COLDEST SPOT EXPECTED OVER CENTRAL WHERE WINDS WILL BE LIGHTEST.
WITH WINDS SHIFTING NORTH AFTER PASSAGE OF SHORT WAVE EXPECT LAKE
EFFECT SHOWERS TO CONTINUE...THOUGH AS RIDGE BUILDS IN INVERSION
HEIGHTS LOWER AND DRIER AIR WORKS IN. HAVE TRENDED DOWN ON
POPS...ESPECIALLY AFTER MIDNIGHT WED NIGHT.
THU NIGHT ONWARD...AIR MASS TRENDING TO MODERATE WITH
TIME...THOUGH NO APPEARANCE OF ANY SIG WAA. WILL SLOWLY BRING
TEMPS UP...THOUGH STILL HAVE HIGHS SOME 5 TO 10 DEGREES BELOW
NORMS. PACIFIC SYSTEM TO DROP SE INTO SOUTHERN PLAINS...THEN LIFT
OUT INTO THE OHIO VALLEY MONDAY TIMEFRAME. SOME DIFFERENCES IN
THE MODELS WITH GFS STRONGER AND FURTHER NORTH BRINGING QPF NORTH
INTO THE REGION. HAVE DOWN PLAYED THAT SCENARIO IN GRIDS...AS GFS
LACK CONSISTENCY IN LATTER PERIODS. HAVE TRENDED TOWARDS ECENS.
CANADIAN HIGH PRESSURE TO DOMINATE AT THE SURFACE WITH WINDS
SHIFTING NE SAT INTO TUE. HAVE BROUGHT CLOUDS UP SLIGHTLY IN THE
EAST WITH FLOW OFF LAKE...THOUGH WITH LIMITED INSTABILITY WILL
STAY DRY.
&&
.AVIATION...VFR CIGS NEAR THE MICHIGAN BORDER BUT OTHERWISE MOSTLY
CLEAR TONIGHT. COLD AIR ALOFT WILL GENERATE MVFR CIGS AND SNOW
SHOWERS AT TIMES WEDNESDAY.
RDM
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
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
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 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 DENVER/BOULDER CO
322 AM MDT WED MAR 20 2013
.SHORT TERM...THE FLOW ALOFT WILL BECOME MORE WLY TODAY AND
TONIGHT AS MOISTURE GRADUALLY INCREASES IN THE MTNS BY LATER THIS
AFTN AND EVENING. THERE IS VERY LITTLE MID LVL ASCENT WITH LAPSE
RATES ON AVERAGE AROUND 6 C/KM. SHOULD SEE SNOW INCREASE IN ZN 31
LATE THIS AFTN AND ACROSS THE REST OF THE MTNS THIS EVENING.
AMOUNTS THRU 12Z THU LOOK TO BE BLO ADVISORY CRITERIA EXCEPT
POSSIBLY IN ZN 31.
OVER NERN CO SURFACE HIGH PRES WILL MOVE INTO THE CNTRL US AS SFC
LOW PRES DEVELOPS OVER ERN CO BY AFTN. THUS WILL SEE INCREASING
SOUTH WINDS OVER THE PLAINS BY AFTN. ALTHOUGH THERE WILL BY AN
INCREASE IN MID AND HIGH CLOUDS AT THIS TIME IT LOOKS DRY THRU THE
AFTN HOURS. HIGHS THIS AFTN WILL RISE INTO THE UPPER 50S TO LOWER
60S OVER NERN CO EXCEPT POSSIBLE OVER THE FAR NERN CORNER WHERE
READINGS WILL BE SLIGHTLY LOWER. FOR TONIGHT MAY SEE A SLIGHT CHC
OF SHOWERS NR THE WY-NE BORDER SO WILL KEEP IN LOW POPHE TREND WOULD BE TO
S IN THESE AREAS.
.LONG TERM...FOR THURSDAY...THERE WILL BE A FAST MOVING EMBEDDED
WAVE IN THE NORTHWEST FLOW PATTERN. THIS WAVE WILL BENEFIT THE
MOUNTAINS THE MOST WITH DECENT OROGRAPHIC FLOW AND STEEPENING
LAPSE RATES BY THURSDAY AFTERNOON. THERE WILL STILL BE A CHANCE OF
SHOWERS OVER THE NORTHEAST PLAINS...BUT DOWNSLOPE NORTHWEST WINDS
WILL LIMIT SHOWER POTENTIAL OVER THE FRONT RANGE. BEST CHANCE WILL
LIKELY BE FURTHER EAST AWAY FROM THE MOUNTAINS. SUBSIDENCE QUICKLY
MOVES IN BEHIND THE WAVE THURSDAY EVENING WITH PRECIP ENDING AND
CLEARING SKIES AND DECREASING WINDS. STILL SOME SNOW SHOWERS IN
THE MOUNTAINS THURSDAY EVENING BEFORE LAPSE RATES STABILIZE AND
MOISTURE BECOMES QUITE SHALLOW.
ATTENTION THEN SHIFTS TOWARDS STRONGER STORM SYSTEM WHICH IS
EXPECTED TO DEVELOP OVER THE NORTHERN GREAT BASIN ON FRIDAY BEFORE
MOVING ACROSS COLORADO ON SATURDAY. YET AGAIN...LONG RANGE MODELS
HAVE TRENDED BACK AWAY FROM THE CLOSED LOW SOLUTION TO A MORE
PROGRESSIVE AND FASTER OPEN WAVE. THE GFS IS NOW THE FASTEST
WHILE THE CANADIAN IS SLOWEST WHILE STILL HOLDING ON TO A CLOSED
LOW NEAR THE 4 CORNERS BY MIDDAY SATURDAY. MOST OF THE GFS
ENSEMBLE MEMBERS SUPPORT THE FASTER MOVING SOLUTION. REGARDLESS OF
EXACT TRACK THERE STILL IS CERTAINLY THE POTENTIAL FOR IMPACT
WINTER WEATHER ON SATURDAY IN THE REGION. NOT MUCH CHANGE TO
ONGOING FORECAST BASED ON MODEL INCONSISTENCIES.
FOR SUNDAY AND MONDAY...MAINLY DRY SUNDAY BUT ANOTHER WEAKER
CLOSED LOW FEATURE OVER THE NORTHERN ROCKIES SLIDES A PIECE OF
ENERGY INTO COLORADO LATE SUNDAY AND MONDAY FOR ANOTHER CHANCE OF
SNOW OVER MUCH OF THE STATE. TEMPERATURES WILL BE BELOW NORMAL FOR
MUCH OF THIS EXTENDED PERIOD.
&&
.AVIATION...WINDS HAVE BECOME LIGHT SLY EARLY THIS MORNING. BOTH
THE HRRR AND RAP SHOW WINDS BECOMING MORE ELY BY MIDDAY. BY LATE
AFTN THERE ARE SOME INDICATIONS THE STRONGER WLY FLOW ALOFT WILL
MIX DOWN TO THE SFC AS A BNDRY COMES OFF THE FOOTHILLS WITH WINDS
BECOMING WLY IN THE 23Z-00Z TIMEFRAME AND CONTINUING THRU THE
EARLY EVENING HOURS. BY MID EVENING WINDS SHOULD BECOME MORE SSW
AND CONTINUE OVERNIGHT. VFR CONDITIONS WILL BE IN PLACE THRU THE
PERIOD WITH ONLY SOME MID AND HIGH LVL CLOUD COVER THIS AFTN AND
TONIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....ENTREKIN
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
146 AM EDT WED MAR 20 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 415 PM EDT TUE MAR 19 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP CLOSED LO
CENTERED OVER ERN LK SUP DOWNSTREAM OF RDG ALONG THE W COAST. DEEP
CYC NW FLOW OF COLD AIR ARND THE SFC LO NEAR WAWA ONTARIO IS
DOMINATING THE CWA...CAUSING LES OVER MAINLY THE WRN ZNS EARLY THIS
AFTN AS -16C H85 TEMPS SHOWN AT INL AT 12Z MOVE OVER THE LAKE. WITH
SHARPENING PRES GRADIENT BTWN PRES RISE CENTER OVER NRN MN AND PRES
FALLS OVER SE ONTARIO TO THE E OF THE SFC LO...THE NW WINDS ARE
STRENGTHENING...WITH WIND GUSTS UP TO 40 MPH REPORTED CAUSING
EXTENSIVE BLSN. THE SN HAS TAPERED OFF OVER THE FAR W AND SCENTRAL
WITH THE ADVECTION OF DRIER AIR OBSVD IN MN AT 12Z/WELL DEPICTED ON
THE 12Z MPX RAOB AND DOWNSLOPE FLOW INTO THE SCENTRAL. PUBLIC
REPORTS INDICATE AS MUCH AS 18 INCHES OF SN HAS FALLEN OVER THE HIER
TERRAIN OF THE W. FARTHER UPSTREAM...ANOTHER SHRTWV IS DIGGING SEWD
THRU LK WINNIPEG.
MAIN FCST CONCERNS THRU WED REMAIN LES/WIND TRENDS AND GOING
HEADLINES AS CLOSED LO DRIFTS ONLY SLOWLY TO THE ENE THRU SE CANADA.
LATE TODAY/TNGT...OVERALL DEEP CYC NW FLOW ARND SLOWLY DEPARTING LO
IS PROGGED TO LINGER AND CAUSE PERSISTENT LES IN THE NW WIND SN
BELTS. THE LES INTENSITY OVER THE FAR W...ESPECIALLY WHERE THE FETCH
ACRS THE OPEN WATER IS SHORTER NEAR IWD...HAS DIMINISHED AS DRIER
AIR IN MN SLID EWD. THIS DRY AIR WL IMPACT MAINLY THE AREAS NEAR THE
WI BORDER. SO THE SCENTRAL SHOULD REMAIN DRY WITH DOWNSLOPING DRIER
FLOW. BUT LATER TNGT...SHRTWV NOW NEAR LK WINNIPEG IS FCST TO DIG
SEWD...CAUSING THE LLVL FLOW TO VEER A BIT AND BRING BACK A RETURN
OF DEEPER MSTR OVER THE ENTIRE CWA ON THE CYC SIDE OF ITS TRACK.
THESE TRENDS SHOULD CAUSE LES TO PICK UP AGAIN AT IWD FOLLOWING A
BREAK THIS EVNG. IN THE NW WIND SN BELTS E OF MQT...THE ARRIVAL OF
COLDER AIR WL LIKELY ENHANCE THE INTENSITY OF THE LES THRU THE NGT
WITH FVRBL WNW LLVL FLOW SHIFTING NW. ANOTHER FACTOR FAVORING HEAVY
SN IS FVRBL ALIGNMENT OF FCST UVV MAX WITHIN THE DGZ EVEN IF STRONG
WINDS THAT CAUSE A BREAK UP OF THE DENDRITES ACT TO REDUCE THE
SN/WATER RATIOS A BIT. BUT THESE STRONG WINDS WL CAUSE EXTENSIVE
BLSN/REDUCED VSBY ESPECIALLY NEAR LK SUP...EVEN WHEN THE LES IS NOT
FALLING HEAVILY.
WED...AS THE CLOSED LO SLOWLY DRIFTS TO THE E...CYC NW FLOW IS
PROGGED TO VEER SLOWLY TO THE NNW. WITH THE ARRIVAL OF SOMEWHAT
WARMER ATLANTIC AIR FM THE NE ARND INTENSE LO PER THE 12Z GFS AND
ESPECIALLY THE NAM...DEEP MSTR IS FCST TO LINGER. ALTHOUGH THE
WARMING WITH H85 TEMPS PROGGED TO RISE TOWARD -10C OVER FAR ERN LK
SUP MIGHT TEND TO REDUCE LES INTENSITY...THE ARRIVAL OF SOME LARGER
SCALE QVECTOR CNVGC/MAINTENANCE OF DEEPER MSTR ASSOCIATED SOME
ISENTROPIC ASCENT WL RETAIN A LK ENHANCED COMPONENT. ALTHOUGH THE
BEST CHC FOR CONTINUED DRY WX WL BE OVER THE SCENTRL...FCST SDNGS
INDICATE THE MSTR WL BE DEEP ENUF TO SUPPORT AT LEAST SCT -SHSN.
SOME OF THE GUIDANCE SUGGESTS SOME DRIER AIR MAY ARRIVE OVER THE W
ON WED AFTN... BUT SLOW MOTION OF THE CLOSED LO TO THE E FAVORS THE
MODELS THAT SHOW A SLOWER EWD PROGRESSION OF THIS DRYING.
GOING HEADLINES LOOK TO BE IN GOOD SHAPE AS LONG DURATION EVENT WL
ADD TO SN ACCUMS THAT HAVE ALREADY HIT WARNING TOTALS IN MOST AREAS
WHERE THESE HEADLINES HAVE BEEN IN EFFECT. EXPECT STORM TOTAL SN TO
REACH 24 INCHES OR MORE OVER THE HIER TERRAIN OF THE W.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 415 PM EDT TUE MAR 19 2013
LOOK FOR A SLOW AND STEADY RISE IN TEMPERATURES THROUGH THE PERIOD
AS WE SLOWLY LOSE THE INFLUENCE OF THE NEARBY 500MB TROUGH.
THE ELONGATED 500MB TROUGH WILL EXTEND FROM JUST NE OF MAINE TO
LOWER MI...AND SOUTHERN UPPER PORTIONS OF UPPER MI AT 00Z
THURSDAY...WITH A SIZABLE RIDGE STRETCHING ACROSS WYOMING AND THE
WESTERN DAKOTAS UP THROUGH SASKATCHEWAN.
WHILE THE 500MB RIDGE WILL PUSH INTO WESTERN UPPER MI/LAKE SUPERIOR
FRIDAY...IT WILL TAKE UNTIL FRIDAY NIGHT UNTIL THE NEARLY STEADY
STATE LOW OVER THE EAST PUSHES OFFSHORE. THE 19/00Z RUNS OF THE
ECMWF AND CANADIAN HOLD ONTO THE TROUGH ACROSS EASTERN UPPER MI A
BIT LONGER THAN THE GFS /BY ROUGHLY 6HRS/. THE SFC TROUGH WILL
LIKELY LINGER ACROSS EASTERN MICHIGAN THROUGH 12Z FRIDAY. THE RESULT
WILL BE CONTINUED LAKE EFFECT SNOW SHOWERS FOR NORTHERLY-NNW WIND
FAVORED LOCATIONS NEAR LAKE SUPERIOR. 850MB TEMPS WILL MODERATE FROM
THE -12 TO -15C AT 00Z THURSDAY TO AROUND -8C BY DAYBREAK FRIDAY.
EXPECT QUICKLY DIMINISHING LAKE EFFECT SNOW SHOWERS AFTER THURSDAY
AFTERNOON...WITH LOWERING INVERSION HEIGHTS
500MB RIDGING WILL BE THE RULE FRIDAY NIGHT THROUGH AT LEAST
SATURDAY NIGHT.
LOOK FOR A CLUSTERED AREA OF LOW PRESSURE CENTERED NEAR MONTANA AT
00Z SATURDAY WILL DIVIDE FRIDAY NIGHT...WITH THE NORTHERN LOW
SPINNING IN PLACE...AND THE SOUTHERN EXTENT OF THE TROUGH DIVING
ACROSS TEXAS AND OKLAHOMA BY LATE SATURDAY AFTERNOON/SATURDAY NIGHT.
THE 00Z RUNS OF THE GFS AND ECMWF WERE FAIRLY CONSISTENT WITH THE
TRACK OF THE SOUTHERN TROUGH...MOVING IT OVER KENTUCKY AND WEST
VIRGINIA BY DAYBREAK MONDAY...WITH THE RIDGE WEAKENING BUT STILL
REMAINING OVER LAKE SUPERIOR AND UPPER MICHIGAN THROUGH AT LEAST
SUNDAY NIGHT. THE 12Z GFS CAME IN WITH THE 500MB LOW SHIFTED APPROX
250MI TO THE NORTHWEST OF THE 00Z RUN TRACK...WHICH WOULD BRING IT
ACROSS LOWER MI AT 00Z TUESDAY. THIS WOULD RESULT IN STRONGER WINDS
FOR CENTRAL AND EASTERN AREAS...AS WELL AS UPSLOPE LES NORTH CENTRAL
WITH SYNOPTIC SNOW HUGGING THE EASTERN COUNTIES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 140 AM EDT WED MAR 20 2013
WITH A COLD CYCLONIC NW FLOW CONTINUING AROUND LOW PRES DEPARTING
SLOWLY THROUGH NORTHERN ONTARIO THIS FCST PERIOD...EXPECT SHSN TO
IMPACT CMX/IWD...WITH IFR/LIFR CONDITIONS PREDOMINATING. THE WORST
CONDITIONS TO VLIFR ARE MOST LIKELY AT THE MORE EXPOSED CMX LOCATION
WITH DEEPER MOISTURE AND STRONGER WINDS. AT SAW...DOWNSLOPING NW
WINDS SHOULD RESULT IN MAINLY MVFR CONDITIONS THRU THE FCST PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 415 PM EDT TUE MAR 19 2013
EXPECT NW GALES/HEAVY FREEZING SPRAY TO LINGER THRU AT LEAST WED
MORNING AS DEEP LO PRES OVER SE ONTARIO EDGES SLOWLY TO THE E AND A
COLD...GUSTY NW WIND CONTINUES. WINDS/FREEZING SPRAY ARE LIKELY TO
DIMINISH OVER THE W WED AFTERNOON FARTHER FROM THE SLOWLY RETREATING
LO.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR
MIZ001>004-009-084.
WINTER STORM WARNING UNTIL 8 AM EDT THURSDAY FOR MIZ006-007-085.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 8 PM EDT /7 PM CDT/ THIS
EVENING FOR LSZ162-240>245-248>251-263>267.
GALE WARNING UNTIL 2 PM EDT /1 PM CDT/ THIS AFTERNOON FOR LSZ162-
243>245-249>251-263>267.
GALE WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR LSZ248.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...JLB
MARINE...KC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1226 AM CDT WED MAR 20 2013
.UPDATE...
ISSUED AT 1226 AM CDT WED MAR 20 2013
FCST TEMPS WERE RUNNING A LITTLE TOO COOL AGAINST THE OBSERVED
TEMP CURVES. SO CURRENT OBS WERE MERGED WITH GFS LAMP TEMPS TO
GET THE FCST BACK ON TRACK THE NEXT 3-6 HRS.
SATL SHOWS THE BATCH OF MID-LEVEL CIGS WILL BE OUT OF THE FCST
AREA BY 07Z. THEN JUST SCT MID CLOUDS. FCST HAS THIS GENERAL TREND
SO NO CHANGES NEEDED.
&&
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 357 PM CDT TUE MAR 19 2013
MORNING UPPER AIR ANALYSIS INDICATES LONGWAVE TROUGHING OVER THE
EASTERN-HALF OF THE CONUS WITH RIDGING OVER THE WEST.
NORTHWESTERLY MID AND UPPER LEVEL FLOW PERSISTS OVER THE CENTRAL
PLAINS AS A RESULT. TROPOSPHERIC FLOW OVER OUR AREA MAXES OUT AT
AROUND 120KTS PER 12Z SOUNDING DATA FROM KOAX AND KLBF. WATER
VAPOR IMAGERY ALSO INDICATES A SUBTLE MID LEVEL PERTURBATION OVER
EASTERN MONTANA...MOVING TO THE SOUTHEAST. AT THE SURFACE A TROUGH
IS NOTED EXTENDING FROM WESTERN IOWA INTO SOUTHEASTERN NEBRASKA
AND KANSAS...WITH A COLD FRONT ALSO NOTED OVER THE DAKOTAS. THE
LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE NORTHWEST AS
A RESULT.
PROXIMITY SOUNDINGS FROM ACROSS CWA...PER RAP ANALYSIS AND LAPS
DATA...SUGGEST VERY STEEP LOW TO MID LEVEL LAPSE RATES ARE IN
PLACE...WITH NEARLY DRY ADIABATIC LAPSE RATES NOTED FROM THE
SURFACE TO BETWEEN 750MB AND 700MB ACROSS MUCH OF OUR AREA. AS A
RESULT...MODEST SBCAPE VALUES ON THE ORDER OF 100-200J/KG ARE IN
PLACE ACROSS MUCH OF THE CWA. AN EXPANDING CU FIELD AS BEEN NOTED
ON SATELLITE IMAGERY ACROSS MUCH OF NEBRASKA AS A RESULT...WITH
KUEX AND KLNX SUGGESTING ELEVATED PRECIPITATION HAS RESULTED. SOME
OF THIS PRECIPITATION IS MAKING IT TO THE SURFACE IN THE FORM OF
RAIN AND GRAUPEL...BOTH OF WHICH WAS OBSERVED AT THE OFFICE
BETWEEN 19Z AND 20Z. IN ADDITION...A COUPLE OF CG STRIKES HAVE
BEEN DETECTED FROM HALL COUNTY INTO BUFFALO COUNTY WITH SOME OF
THE MORE INTENSE CELLS. WITH ANY OMEGA STILL REMAINING WELL
NORTHWEST OF OUR AREA OVER THE NORTHERN HIGH PLAINS...IN THE
VICINITY OF THE AFOREMENTIONED MID LEVEL PERTURBATION...IT APPEARS
THE CURRENT ACTIVITY IS BEING PROMOTED BY DIABATIC HEATING ALONE.
SO...THIS ACTIVITY SHOULD CONTINUE THROUGH 22Z OR 23Z BEFORE THE
LOSS OF DIABATIC HEATING IS REALIZED LATER THIS EVENING. WENT
AHEAD WITH ISOLATED RAIN AND SNOW SHOWERS...ALONG WITH OCCASIONAL
LIGHTNING...IN THE FORECAST THROUGH 00Z.
THE SAME PROXIMITY SOUNDINGS FROM ACROSS THE CWA ALSO INDICATE
VERY DRY LOWER TROPOSPHERIC AIR IN PLACE ACROSS THE AREA...THUS
RESULTING IN DEEP INVERTED-V SOUNDINGS ACROSS THE ENTIRE CWA.
GIVEN THE ABUNDANT VIRGA NOTED HERE AT THE OFFICE...ALONG WITH THE
UPDRAFT STRENGTH NOTED FROM KUEX THROUGH THE PAST HOUR...FELT IT
PRUDENT TO INTRODUCE BRIEF WIND GUSTS TO AROUND 50 MPH IN THE HWO
THROUGH THIS EVENING.
THE MID LEVEL PERTURBATION...CURRENTLY OVER THE NORTHERN HIGH
PLAINS...IS EXPECTED TO SWEEP OVER OUR AREA TONIGHT. ANY OMEGA IN
ASSOCIATION WITH THIS FEATURE IS EXPECTED TO REMAIN WEAK AND WITH
NO OTHER SIGNIFICANT SOURCE OF LIFT DURING THE SHORT TERM
FORECAST PERIOD...DRY CONDITIONS ARE FORECAST TONIGHT INTO
TOMORROW.
THE PASSAGE OF THE MID LEVEL PERTURBATION WILL ALSO HELP PUSH THE
LOW LEVEL BAROCLINIC ZONE...CURRENTLY OVER THE DAKOTAS...ACROSS
OUR AREA TONIGHT. THIS WILL IN TURN ALLOW A COOLER AIRMASS INTO
OUR REGION THUS RESULTING IN SOMEWHAT COOLER WEDNESDAY MORNING
LOWS WHEN COMPARED TO TUESDAY MORNING. OVERNIGHT LOWS IN THE TEENS
AND 20S ARE CURRENTLY FORECAST FOR TONIGHT AS A RESULT. THE
SURFACE RIDGE IS THEN EXPECTED TO PUSH OFF TO OUR EAST DURING THE
DAY WEDNESDAY...WITH LOW LEVEL RETURN FLOW AND RESULTANT WARM AIR
ADVECTION ALLOWING WEDNESDAY AFTERNOON HIGHS TO CLIMB INTO THE 40S
AND LOWER 50S FOR MOST LOCATIONS ACROSS THE AREA.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 357 PM CDT TUE MAR 19 2013
WEDNESDAY NIGHT THROUGH TUESDAY. PRIMARY FORECAST CONCERN REVOLVES
AROUND A MESSY PATTERN WITH MULTIPLE PRECIPITATION CHANCES
DURING THE LATE WORK WEEK/WEEKEND TIME FRAME.
STILL EXPECTING THE START OF THE LONG TERM PERIOD TO BE DRY...WITH
MODELS IN GOOD AGREEMENT SHOWING NORTHWESTERLY FLOW SET UP IN THE
UPPER LEVELS ACROSS THE REGION WEDNESDAY EVENING INTO THE
OVERNIGHT HOURS...WITH AN ELONGATED LOW PRESSURE SYSTEM SPREAD
FROM THE NORTHEASTERN CONUS THROUGH THE GREAT LAKES...AND
SHORTWAVE RIDGING OVER THE ROCKIES AHEAD OF ANOTHER TROUGH ALONG
THE WEST COAST. AT THE SURFACE...THE CWA SITS BETWEEN A RIDGE OF
HIGH PRESSURE ALONG/JUST EAST OF THE MISSOURI RIVER...AND LOW
PRESSURE EXTENDING FROM THE NORTHERN ROCKIES DOWN INTO SERN
COLORADO...BRINGING SOUTHEASTERLY WINDS TO THE AREA.
AS WE GET INTO EARLY THURSDAY MORNING...STILL SEEING THE MAIN
MID/UPPER LEVEL TROUGH/LOW PRESSURE SYSTEM IN PLACE TO THE
WEST...WITH THE FIRST OF A COUPLE OF DISTURBANCES EJECTED OUT
AHEAD OF IT BEGINNING TO AFFECT THE REGION. MAIN CHANGE WITH THE
MODELS HAS BEEN WITH MORE AGREEMENT BACKING OFF THE COVERAGE OF
PRECIPITATION ACROSS THE CWA...THERE IS PLENTY OF DRIER AIR TO
OVERCOME...AND BETTER CHANCES LOOK TO BE ACROSS EASTERN PORTIONS
OF THE CWA DURING THE DAY ON THURSDAY AS THE MID LEVEL TROUGH AXIS
SWINGS THROUGH AND FRONTOGENETICAL LIFT INCREASES. REALLY TAPERED
BACK POPS...ESP ACROSS THE WRN THIRD OF THE CWA...IT IS POSSIBLE
AFTER 12Z THURSDAY SOME WESTERN LOCATIONS MAY NOT SEE MUCH OF
ANYTHING. DIDNT WANT TO COMPLETELY PULL POPS YET...WANT TO SEE
SOME CONSISTENCY WITH THIS TREND FIRST. DECIDED TO HOLD ON TO THE
MIXED PRECIPITATION ACROSS THE SWRN CWA DURING THE EARLY/MID
MORNING HOURS ON THURSDAY...BUT CONFIDENCE IS NOT HIGH IN IT
OCCURRING. IF PRECIPITATION OCCURS AT ALL IN THAT PART OF THE
CWA...CANT COMPLETELY RULE OUT A BRIEF PERIOD OF MORE OF A
MIX...BUT NOT EXPECTING IT TO AMOUNT TO MUCH.
BUMPED UP HIGH TEMPERATURES ON THURSDAY ONCE AGAIN WITH MODELS
TRENDING TOWARD THE POTENTIAL FOR DRIER CONDITIONS DURING THE
AFTERNOON HOURS...SWRN LOCATIONS COULD REACH INTO THE LOWER/MID
40S. THINK THE NORTHEAST HALF WILL STRUGGLE WITH PRECIP/MORE CLOUD
COVER LINGERING LONGER INTO THE DAY.
SHOULD SEE A LULL IN THE ACTIVITY LATER IN THE DAY THURSDAY AND
INTO THURSDAY EVENING...BUT IT WILL BE A BRIEF BREAK WITH THE
NEXT DISTURBANCE TAKING AIM ON THE REGION. MODELS SHOWING THE MAIN
TROUGH OVER THE NORTHWESTERN CONUS/NRN ROCKIES TRYING TO EVOLVE
INTO A CLOSED CIRCULATION AS ANOTHER 110+KT UPPER LEVEL JET STREAK
DIGS INTO THE WEST COAST. ANOTHER SHORTWAVE DISTURBANCE EJECTED
OUT FROM THIS SYSTEM LOOKS TO BRING ANOTHER CHANCE FOR
PRECIPITATION TO THE CWA. THERE CONTINUE TO BE SOME SLIGHT
DIFFERENCES...BUT MODELS HAVE TRENDED TOWARD MORE AGREEMENT
SHOWING THE TIMING COMING DURING THURSDAY NIGHT INTO THE FIRST
HALF OF THE DAY ON FRIDAY. THINKING THE PRIMARY PRECIPITATION TYPE
FOR MOST WILL BE SNOW...BUT CANT RULE OUT MORE OF A RA/SN
MIX...MAINLY ACROSS THE SOUTHERN CWA. LIKE THURSDAY...TRENDED BACK
POPS ON FRIDAY...THE BETTER CHANCES COME DURING THE 00-12Z FRIDAY
TIME FRAME...WITH VERY LITTLE IN THE WAY OF POPS DURING THE
AFTERNOON HOURS. BECAUSE OF THIS...ALSO BUMPED UP HIGHS ON
FRIDAY...WITH MID 30S IN THE NORTHEAST TO LOWER/MID 40S IN THE
SOUTHWEST.
FRIDAY AFTERNOON AND INTO THE OVERNIGHT HOURS WILL BRING ANOTHER
LULL IN THE ACTIVITY...BEFORE FOCUS QUICKLY TURNS TO A STRONGER
SYSTEM WHICH WILL BRING THE POTENTIAL FOR MORE WIDESPREAD
ACCUMULATING SNOWFALL TO THE REGION. BY EARLY SATURDAY
MORNING...MODELS HAVE STARTED TO COME INTO BETTER AGREEMENT
SHOWING THE DEVELOPMENT OF A LOW PRESSURE SYSTEM OVER THE BORDER
OF MONTANA/CANADA...WHILE A PIECE OF ENERGY SWINGING FURTHER SOUTH
INTO THE ROCKIES DOES THE SAME...AND ITS THIS SOUTHERN ONE WHICH
WILL AFFECT OUR CWA. LIFT WILL BEGIN TO INCREASE ACROSS THE CWA
OUT AHEAD OF THIS SYSTEM LATE FRIDAY NIGHT...ALREADY BRINGING
PRECIPITATION CHANCES TO MAINLY THE WESTERN HALF OF THE CWA.
THROUGH THE DAYTIME HOURS ON SATURDAY THIS UPPER LEVEL LOW WILL
CONTINUE TO PUSH EAST...BRINGING INCREASING PRECIPITATION
CHANCES...AND BY 00Z LOOKS TO BE OVER CENTRAL/ERN PORTIONS OF
COLORADO. THERE ARE SOME TIMING DIFFERENCES...THE ECMWF/GFS ARE IN
PRETTY GOOD AGREEMENT...WITH THE GEM A TOUCH SLOWER. WHAT HAPPENS
THEN THROUGH THE OVERNIGHT HOURS SATURDAY NIGHT AND THEN INTO
SUNDAY IS GOING TO DEPEND ULTIMATELY ON THE PATH/TIMING OF THIS
UPPER LEVEL LOW. THE TIMING/PATH DIFFERENCES BETWEEN THE MODELS
CONTINUE...BUT THEY ALL BRING MORE WIDESPREAD SNOWFALL
ACCUMULATION. THIS IS ESPECIALLY TRUE WITH THE GEM...WHICH IS THE
SLOWEST AND MOST WOUND UP SYSTEM COMPARED TO THE ECMWF/GFS...BUT
ITS PATH IS SOMEWHAT IN BETWEEN THE TWO...TAKING IT MORE THROUGH
CENTRAL KS. THERE ARE PLENTY OF THINGS TO WORK OUT IN THE COMING
DAYS...AND EXPECT MODEL CHANGES...BUT THOSE WITH WEEKEND PLANS
NEED TO KEEP AN EYE ON THIS SYSTEM. AS FAR AS TEMPERATURES
GO...EXPECTING HIGHS TO STRUGGLE TO GET OUT OF THE MID 30S BOTH
SATURDAY AND SUNDAY.
LOOKING AHEAD TO MONDAY AND TUESDAY...KEPT THE FORECAST DRY...BUT
THE MESSY UPPER LEVEL PATTERN REMAINS. MODELS KEEP THE REGION
UNDER THE INFLUENCE OF A BROAD TROUGH...WITH PIECES OF
ENERGY/LOW PRESSURE SYSTEMS ROTATING AROUND EACH OTHER. IN THIS
PATTERN...CERTAINLY WOULNDT BE SEEING MUCH/IF ANY WARM UP...WITH
HIGHS REMAINING IN THE 30S /AVERAGE FOR THIS TIME OF YEAR IS THE
LOWER 50S/...AND ITS NOT OUT OF THE REALM OF POSSIBILITY THAT SOME
OF THIS ENERGY COULD BRING ANOTHER CHANCE FOR PRECIPITATION...ESP
TUESDAY. BUT AT THIS POINT...WITH THERE ALREADY ENOUGH UNCERTAINTY
THROUGH THE WEEKEND...WASNT CONFIDENT ENOUGH TO GO WITH ANY POPS
FOR DAY 7.
&&
.AVIATION...(FOR THE 06Z TAF THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1226 AM CDT WED MAR 20 2013
REST OF TNGT: VFR. A BATCH OF MID-LEVEL CIGS HAS DROPPED S OF THE
TERMINAL AND JUST A FEW-SCT 7-9K FT CLOUDS WILL DRIFT THRU. WINDS
WILL REMAIN NNE BELOW 10 KTS AND GRADUALLY DIMINISHING. AFTER 10Z
WINDS WILL BECOME LGT AND VARIABLE AS HIGH PRES SLIDES THRU.
WED: VFR WITH JUST A COUPLE SKIFFS OF 25K FT CIRRUS. LGT AND
VARIABLE WINDS ORGANIZE FROM THE NW BELOW 10 KTS BEFORE
DIMINISHING AGAIN 21Z-03Z.
WED EVE: VFR MID-LEVEL CIGS INVADE WITH WINDS DEVELOPING FROM THE
ESE AT 10-15 KTS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...BRYANT
LONG TERM...ADO
AVIATION...HALBLAUB
YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
909 AM EDT WED MAR 20 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM WELL TO OUR NORTH WILL TRACK INTO THE CANADIAN
MARITIMES TODAY, WITH A COLD FRONT CROSSING OUR REGION LATE TODAY
AND INTO TONIGHT. MEANWHILE, ANOTHER LOW PRESSURE SYSTEM WILL EMERGE
OFF THE SOUTHEASTERN SEABOARD TONIGHT AND INTENSIFY AS IT TRACKS
WELL OFF THE MID ATLANTIC COAST THROUGH THURSDAY. HIGH PRESSURE IS
THEN FORECAST TO INFLUENCE OUR REGION FRIDAY THROUGH SUNDAY. FOR
EARLY NEXT WEEK, A COASTAL LOW MAY AFFECT THE AREA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BASED ON THE 12Z SOUNDING FULL SUN MACROS, WE BUMPED UP MAX
TEMPERATURES SLIGHTLY. BASED ON THE LATEST HRRR AND ONGOING
ECHOES, WE FILLED IN THE GAP OF FLURRIES IN THE POCONOS.
OTHERWISE, THE REST OF THE FORECAST REMAINS CLOSE AND NO OTHER BIG
CHANGES WERE MADE.
AFTER A SUNNY BRISK START WITH WESTERLY WINDS GUSTING 25 TO 30 MPH
THROUGH MID AFTERNOON...SKIES CLOUD UP RAPIDLY BETWEEN 6 AND 10000
FT VERY LATE IN THE AFTN (5PM IN RESPONSE TO FGEN AHEAD OF OUR
FORMING COLD FRONT). WINDS BELOW 950 MB TURN SSW AND INCREASE ALONG
THE DELMARVA WITH MOISTURE ADVECTION BY EVENING.
TEMPS/WINDS ARE 50 50 BLENDED 00Z/20 NAM/GFS MOS GUIDANCE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
YOU`VE SEEN THE FAR TOO ROBUST NAM QPF FROM THE 06Z CYCLE...
NEVERTHELESS THE MODEL IS CUING FOR WHAT I THINK SHOULD BE 2 NICE
SNOW SHOWER BANDS. THE FIRST MAY BE TOO WARM TO SUPPORT MUCH SNOW
ACCUM PRIOR TO 05Z EXPECT MAYBE CHESTER COUNTY. THE LATTER TWD 10Z
MAY BE MORE PRODUCTIVE NEAR THE S OR CENTRAL NJ COAST.
COULD BE AN INTERESTING HOUR OR TWO DURING THE NIGHT IN AN AXIS
FROM KPHL TO KNEL OR SLIGHTLY FURTHER SOUTH. AXIS OF HIGH TT AND KI
(MID 50S AND MID 20S RESPECTIVELY) REFLECTS FGEN MOISTENING A FAIRLY
STEEP LOW LVL LAPSE RATE THAT SHOULD PRODUCE TWO NE-SW BANDS OF LIGHT
TO MDT SNOW SHOWERS. WHILE THE INITIAL SNOWFALL SHOULD MELT ON CONTACT...I
DO THINK THERE WILL BE AN ACCUMULATION. ITS SNOW SHOWERS...SO
WHERE THE BANDS ARE MOST PRODUCTIVE IS NOT EASY TO BE SURE OF BUT
THINK THAT MANY OF US FROM SE PA INTO NJ AND POSSIBLY N DE WILL
AWAKE THURSDAY MORNING TO A FRESH COVER OF SNOW WITH POTENTIAL FOR
ROAD TREATMENTS. TWO DAYS AGO...THIS LOOKED TO BE BEST FIT FOR THE
HIGHER TERRAIN OF E PA BUT TRENDS HAVE BEEN SEWD AND SO...IT APPEARS
TO ME THAT CENTRAL OR SNJ IS A BEST FIT FOR VARIABLE AMOUNTS OF
1/2 TO 1 INCH SNOW ON GRASS...POTENTIAL EXISTING FOR 2 INCH AMTS IN A
COUPLE OF LOCATIONS. PAVEMENT LESS BUT PAVEMENT CAN BECOME SLIPPERY
FM THIS LATER ON IF THE READ ON THE CONVECTIVE NATURE IS CORRECT.
FCST TEMPERATURES/WINDS WERE A STRAIGHT 50 50 BLEND OF THE 00Z/20
NCEP MOS.
FOR THIS TO BE A FAILED FCST LOOK FOR THE FUTURE 12Z/20 NAM AND GFS
TO QUIT GENERATING PCPN FOR THIS COMING NIGHT. IF THE MODELED
AMOUNTS ARE JUST .01 OR .03 THEN ITS NOT GOING TO BE MUCH IF
ANYTHING AT ALL. BUT...IF THE MODEL AMTS CONTINUE TO ADVERTISE A
12 HOUR TOTAL OF .1 OR GREATER...THEN WE ARE IN BUSINESS.
FOR THOSE WHO LOOK AT OTHER MODELS...MYSELF..I EXPERIENCE MORE
SUCCESS USING THE NCEP MODELS IN QPF GENERATION FOR CONVECTIVE
TYPE EVENTS.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
TO START THE LONG TERM, A WEAK LOW IS PROGGED TO BE NEAR THE MID
ATLANTIC REGION, WITH MID-LEVEL TROUGHING BACK OVER THE
APPALACHIANS. THIS WEAK LOW IS FORECAST TO MERGE WITH A MUCH
STRONGER AREA OF LOW PRESSURE THAT WILL BE ADVANCING NORTHEASTWARD
WELL OFF THE MID ATLANTIC COAST DURING THURSDAY. OVERALL MOISTURE
AND LIFT ASSOCIATED WITH THE WEAK LOW NEAR THE MID ATLANTIC THURSDAY
MORNING ARE NOT OVERLY IMPRESSIVE, BUT WE DID RETAIN SLIGHT CHANCE
POPS FOR LIGHT RAIN/SNOW ACROSS MUCH OF THE REGION FOR A TIME.
RELATIVELY QUIET WEATHER IS THEN EXPECTED FROM FRIDAY THROUGH SUNDAY
AS HIGH PRESSURE FROM CENTRAL CANADA INFLUENCES OUR REGION. A RATHER
COOL NORTHWEST FLOW ALOFT WITH A MID-LEVEL LOW REMAINING PRESENT TO
OUR NORTH THROUGH THIS TIMEFRAME WILL KEEP CONDITIONS ON THE COOL
SIDE WITH TEMPERATURES RUNNING BELOW MID TO LATE MARCH AVERAGES.
GOING INTO EARLY NEXT WEEK, THE GFS AND ECMWF BOTH SHOW DEVELOPING
LOW PRESSURE IN THE OHIO VALLEY. A SECONDARY COASTAL LOW IS ALSO
FORECAST TO EMERGE OFF THE SOUTHEASTERN SEABOARD SUNDAY AFTERNOON
AND SUBSEQUENTLY TRACK NORTHEAST NEAR THE MID ATLANTIC COAST SUNDAY
NIGHT INTO MONDAY BEFORE MOVING OUT TO SEA MONDAY NIGHT. DIFFERENCES
REMAIN AT THIS EXTENDED TIMEFRAME REGARDING THE TRACK AND INTENSITY
OF THESE LOW PRESSURE SYSTEMS, WITH THE GFS GENERALLY SHOWING
STRONGER SURFACE LOWS. THERMAL FIELDS ALSO DIFFER BETWEEN THE
MODELS, AND THIS LOOKS TO BE ANOTHER MIXED RAIN/SNOW EVENT, WITH THE
GREATEST CHANCES FOR MORE IN THE WAY OF FROZEN PRECIPITATION BEING
ACROSS OUR NORTHWEST ZONES. OVERALL, THIS WILL BE THE NEXT
POTENTIALLY SIGNIFICANT SYSTEM ON THE HORIZON TO WATCH, AND OVER THE
NEXT FEW DAYS, THE DETAILS OF PRECIP TYPE AS WELL AS TIMING CAN BE
IRONED OUT AS THE MODELS COME TO CLOSER AGREEMENT.
&&
.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
AFTER 12Z...VFR WITH W GUSTS TO NEAR 25 KT. WINDS BACK LATE IN
THE DAY AND DIMINISH WITH VFR CIGS FORMING BETWEEN 6000 AND 10000
FT NEAR 21Z.
TONIGHT...CIGS LOWER TO 5000 FT MOST TAF LOCATIONS WITH A PERIOD
OF MVFR OR IFR CONDS PROBABLE FOR KILG/KPHL/KPNE/KTTN/KACY/KMIV
IN SNOW SHOWERS. BEST WINDOW OF OPPORTUNITY APPEARS TO BE AFTER
05Z.
LIGHT WINDS BECOMING N 10-15 KTS BY MORNING.
OUTLOOK...
THURSDAY...POSSIBLE MVFR AND LEFTOVER LIGHT SNOW SHOWERS DURING
THE MORNING, WITH IMPROVEMENT TO VFR FROM WEST TO EAST DURING THE
AFTERNOON.
FRIDAY THROUGH SATURDAY...MAINLY VFR CONDITIONS.
SUNDAY...MAINLY VFR. CONDITIONS MAY BEGIN TO LOWER SUNDAY NIGHT WITH
POSSIBLE RAIN/SNOW.
&&
.MARINE...
CONVERTED GALE TO SCA CONDS TODAY. COULD HAVE ISOLATED GALE GUST
DURING MIDDAY BUT ITS NOT WORTH A GALE WARNING... JUST APPEARS TOO
DIFFICULT TO ACHIEVE MULTIPLE HOUR GALE GUSTS TODAY AT ANY ONE
LOCATION.
TONIGHT...NO HEADLINE ANTICIPATED. WINDS EAST OF DE AND AND S NJ
BECOME SSW G 20 KTS FOR A TIME WHILE ELSEWHERE WINDS SHOULD BECOME
LIGHT. THEN ALL AREAS SHIFT TO THE N BY 8AM THURSDAY WITH G TO 20
KTS.
THERE IS A SMALL CHANCE FOR G 25 KTS OFF THE DE WATERS NEAR 12Z
THU.
OUTLOOK...
SCA CONDITIONS MAY BE POSSIBLE FOR A TIME ON THURSDAY WITH GUSTY
WEST TO NORTHWEST WINDS AS AN INTENSIFYING LOW PRESSURE SYSTEM MOVES
WELL OFF THE MID ATLANTIC COAST. FROM FRIDAY AND INTO THE WEEKEND,
CONDITIONS ARE EXPECTED TO BE BELOW SCA CRITERIA AS HIGH PRESSURE
INFLUENCES THE REGION. EARLY NEXT WEEK, A COASTAL LOW MAY AFFECT
THE AREA WATERS.
&&
.FIRE WEATHER...
WE CONTACTED NJ FORESTRY AND NON 10 HR FUELS REMAIN TOO WET FOR THE
RAPID SPREAD OF WILDFIRES.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ430-
431-450>455.
&&
$$
SYNOPSIS...KLINE
NEAR TERM...DRAG/GIGI
SHORT TERM...DRAG
LONG TERM...KLINE
AVIATION...DRAG/KLINE
MARINE...DRAG/KLINE
FIRE WEATHER...GIGI
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1029 AM MDT WED MAR 20 2013
.UPDATE...
&&
.SHORT TERM...CURRENT FORECASTS LOOK ON TRACK AT THIS TIME.
MOISTURE TO SPREAD ACROSS MOUNTAINS THIS AFTERNOON ALONG WITH SOME
MID LEVEL ASCENT. WITH LAPSE RATES AROUND 6 C/KM...SHOULD SEE SOME
SNOW SHOWERS DEVELOP...BEST CHANCE FOR SHOWERS LATE THIS AFTERNOON
OVER ZONE 31 AND THE REST OF THE MOUNTAINS TONIGHT WHEN THE LATEST
RAP SHOWS THE BEST ASCENT MOVING OVERHEAD. FAVORED OROGRAPHICS IN
WESTERLY FLOW...THOUGH SNOW AMOUNTS STILL APPEAR LESS THAN
ADVISORY FOR ZONE 31 TONIGHT. ACROSS PLAINS...SOUTHERLY WINDS AND
A BIT OF WARM AIR ADVECTION SHOULD DRIVE TEMPERATURES CLOSE TO 60
DEGREES. BUT LATEST WRF SYNTHETIC SATELLITE IMAGERY INDICATING
SOME INCREASE IN MID AND HIGH LEVEL MOISTURE WHICH COULD HINDER
WARMUP. MAY NEED TO SHAVE A FEW DEGREES OFF THE MAX TEMP GRIDS BUT
WILL WAIT TO SEE WHAT DEVELOPS. PERHAPS A FEW SHOWERS THIS EVENING
ALONG THE WYOMING AND NEBRASKA BORDERS AS SOME MID LEVEL ASCENT
MOVES ACROSS WYOMING.
.AVIATION...WEAK CONVERGENCE ZONE HAS DEVELOPED FROM NORTHEAST OF
DIA TO NORTHERN ELBERT COUNTY...WITH WEAK WEST TO NORTHWEST WINDS
AT KDEN...SOUTHWEST AT KAPA AND NORTHWEST AT KBJC. WINDS APPEARS
THIS ZONE IS SLOWLY SHIFTING EAST...WOULD EXPECT WINDS AT KDEN TO
BECOME A BIT MORE NORTHERLY BY 18Z...THEN NORTHEAST TO EAST DURING
THE AFTERNOON. WILL TREND KAPA MORE SOUTHWEST THROUGH THE
AFTERNOON...KEEPING LIGHT NORTHWEST WINDS AT KBJC. REST OF TAF
TRENDS SEEM ON TRACK. LATEST RAP STILL INDICATING SOME SORT OF A
WESTERLY BOUNDARY MOVING ACROSS THE DENVER AREA BETWEEN 21Z AND
00Z. THIS STILL SEEMS REASONABLE AS SOME MIXING COULD
OCCUR BUT WILL LOWER SPEEDS A BIT.
&&
.PREV DISCUSSION... /ISSUED 322 AM MDT WED MAR 20 2013/
SHORT TERM...THE FLOW ALOFT WILL BECOME MORE WLY TODAY AND
TONIGHT AS MOISTURE GRADUALLY INCREASES IN THE MTNS BY LATER THIS
AFTN AND EVENING. THERE IS VERY LITTLE MID LVL ASCENT WITH LAPSE
RATES ON AVERAGE AROUND 6 C/KM. SHOULD SEE SNOW INCREASE IN ZN 31
LATE THIS AFTN AND ACROSS THE REST OF THE MTNS THIS EVENING.
AMOUNTS THRU 12Z THU LOOK TO BE BLO ADVISORY CRITERIA EXCEPT
POSSIBLY IN ZN 31.
OVER NERN CO SURFACE HIGH PRES WILL MOVE INTO THE CNTRL US AS SFC
LOW PRES DEVELOPS OVER ERN CO BY AFTN. THUS WILL SEE INCREASING
SOUTH WINDS OVER THE PLAINS BY AFTN. ALTHOUGH THERE WILL BY AN
INCREASE IN MID AND HIGH CLOUDS AT THIS TIME IT LOOKS DRY THRU THE
AFTN HOURS. HIGHS THIS AFTN WILL RISE INTO THE UPPER 50S TO LOWER
60S OVER NERN CO EXCEPT POSSIBLE OVER THE FAR NERN CORNER WHERE
READINGS WILL BE SLIGHTLY LOWER. FOR TONIGHT MAY SEE A SLIGHT CHC
OF SHOWERS NR THE WY-NE BORDER SO WILL KEEP IN LOW POPHE TREND WOULD BE TO
S IN THESE AREAS.
LONG TERM...FOR THURSDAY...THERE WILL BE A FAST MOVING EMBEDDED
WAVE IN THE NORTHWEST FLOW PATTERN. THIS WAVE WILL BENEFIT THE
MOUNTAINS THE MOST WITH DECENT OROGRAPHIC FLOW AND STEEPENING
LAPSE RATES BY THURSDAY AFTERNOON. THERE WILL STILL BE A CHANCE OF
SHOWERS OVER THE NORTHEAST PLAINS...BUT DOWNSLOPE NORTHWEST WINDS
WILL LIMIT SHOWER POTENTIAL OVER THE FRONT RANGE. BEST CHANCE WILL
LIKELY BE FURTHER EAST AWAY FROM THE MOUNTAINS. SUBSIDENCE QUICKLY
MOVES IN BEHIND THE WAVE THURSDAY EVENING WITH PRECIP ENDING AND
CLEARING SKIES AND DECREASING WINDS. STILL SOME SNOW SHOWERS IN
THE MOUNTAINS THURSDAY EVENING BEFORE LAPSE RATES STABILIZE AND
MOISTURE BECOMES QUITE SHALLOW.
ATTENTION THEN SHIFTS TOWARDS STRONGER STORM SYSTEM WHICH IS
EXPECTED TO DEVELOP OVER THE NORTHERN GREAT BASIN ON FRIDAY BEFORE
MOVING ACROSS COLORADO ON SATURDAY. YET AGAIN...LONG RANGE MODELS
HAVE TRENDED BACK AWAY FROM THE CLOSED LOW SOLUTION TO A MORE
PROGRESSIVE AND FASTER OPEN WAVE. THE GFS IS NOW THE FASTEST
WHILE THE CANADIAN IS SLOWEST WHILE STILL HOLDING ON TO A CLOSED
LOW NEAR THE 4 CORNERS BY MIDDAY SATURDAY. MOST OF THE GFS
ENSEMBLE MEMBERS SUPPORT THE FASTER MOVING SOLUTION. REGARDLESS OF
EXACT TRACK THERE STILL IS CERTAINLY THE POTENTIAL FOR IMPACT
WINTER WEATHER ON SATURDAY IN THE REGION. NOT MUCH CHANGE TO
ONGOING FORECAST BASED ON MODEL INCONSISTENCIES.
FOR SUNDAY AND MONDAY...MAINLY DRY SUNDAY BUT ANOTHER WEAKER
CLOSED LOW FEATURE OVER THE NORTHERN ROCKIES SLIDES A PIECE OF
ENERGY INTO COLORADO LATE SUNDAY AND MONDAY FOR ANOTHER CHANCE OF
SNOW OVER MUCH OF THE STATE. TEMPERATURES WILL BE BELOW NORMAL FOR
MUCH OF THIS EXTENDED PERIOD.
AVIATION...WINDS HAVE BECOME LIGHT SLY EARLY THIS MORNING. BOTH
THE HRRR AND RAP SHOW WINDS BECOMING MORE ELY BY MIDDAY. BY LATE
AFTN THERE ARE SOME INDICATIONS THE STRONGER WLY FLOW ALOFT WILL
MIX DOWN TO THE SFC AS A BNDRY COMES OFF THE FOOTHILLS WITH WINDS
BECOMING WLY IN THE 23Z-00Z TIMEFRAME AND CONTINUING THRU THE
EARLY EVENING HOURS. BY MID EVENING WINDS SHOULD BECOME MORE SSW
AND CONTINUE OVERNIGHT. VFR CONDITIONS WILL BE IN PLACE THRU THE
PERIOD WITH ONLY SOME MID AND HIGH LVL CLOUD COVER THIS AFTN AND
TONIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....ENTREKIN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
340 PM EDT WED MAR 20 2013
.SHORT TERM (TONIGHT-FRIDAY)...
FOR THE REST OF THIS AFTERNOON...SHOWERS WITH A FEW THUNDERSTORMS
SHOULD BE MOVING OVER THE AREA AS THE CONVECTION IN THE GULF KICKS
OUT WITH THE NEXT UPPER DISTURBANCE. THE WEAK SURFACE LOW OVER THE
PENINSULA SHOULD ALSO CONTINUE TO LIFT E/NE TO OVER THE ATLANTIC
AND DRAG A COLD FRONT THROUGH THE AREA. THE SHOWERS AND
THUNDERSTORMS SHOULD CLEAR QUICKLY OUT OF THE AREA AROUND
00Z...BUT HAVE KEPT 20 PERCENT CHANCES IN THROUGH 06Z AS ITS
DEPENDENT ON HOW STRONG A PUSH THE NEXT BAND OF ENERGY HAS ONCE IT
INTERACTS WITH THE CONVECTION THAT HAS BEEN STREAMING CLOUDS AND
SOME STRATIFORM RAIN ACROSS THE AREA THROUGH THE DAY. WILL BE
PUTTING A PRE-FIRST PERIOD INTO THE ZONES TO SHOW THE CONTINUING
LATE AFTERNOON EXPECTED HIGH RAIN CHANCES. WINDS QUICKLY SHIFT
AROUND TO THE SE FOR FRIDAY ALLOWING FOR SOME MOISTURE RETURN AS
HIGH PRESSURE CONTINUES TO RIDGE ACROSS THE AREA. WITH THE
MOISTURE RETURN HAVE ADDED AN AFTERNOON 20 PERCENT RAIN CHANCE.
TEMPERATURES TONIGHT WILL BE IN THE LOWER 40S NORTH...AND IN THE
UPPER 40S TO MID 50S ELSEWHERE. THURSDAY HIGHS WILL BE IN THE MID
60S NORTH AND COASTAL TO THE MID 70S SOUTH. THURSDAY NIGHT WILL
FALL INTO THE MID 30S NORTH TO THE LOWER 40S TO LOWER 50S CENTRAL
AND SOUTH. AND HIGHS FRIDAY WILL BE WARMING TO THE LOWER 70S NORTH
TO THE LOWER 80S SOUTH.
.LONG TERM (FRIDAY NIGHT-TUESDAY)...
THE LONG TERM PERIOD BEGINS FRIDAY NIGHT WITH SURFACE HIGH
PRESSURE OFF THE EAST COAST OF FLORIDA SLIDING FARTHER EAST.
MEANWHILE A REMNANT FRONTAL BOUNDARY WILL MOVE BACK NORTH THROUGH
FLORIDA AND THE EASTERN GULF AS A WARM FRONT BRINGS WINDS BACK
AROUND TO THE SOUTH. A SHORTWAVE PASSING ALONG THE NORTHERN GULF
COAST SATURDAY AND SATURDAY NIGHT WILL TAKE ADVANTAGE OF THE
SURFACE BOUNDARY AND MOIST SOUTHERLY LOW LEVEL WINDS TO FUEL
SHOWERS AND THUNDERSTORMS OVER THE NORTHERN HALF OF THE AREA.
BEFORE RAIN CHANCES GET AN OPPORTUNITY TO SUBSIDE...A COLD FRONT
ASSOCIATED WITH MID LEVEL TROUGHING WILL MOVE ACROSS THE AREA
SUNDAY AND SUNDAY NIGHT WITH ANOTHER WAVE OF CHANCE POPS MOVING
ACROSS THE ENTIRE AREA. THE FRONT WILL STALL OVER SOUTH FLORIDA
WITH SLIGHT CHANCE (20 PERCENT) POPS LINGERING OVER SOUTHERN AND
CENTRAL FLORIDA THROUGH THE EARLY PART OF THE WEEK.
TEMPERATURES WILL GET A CHANCE TO WARM UP TO SEVERAL DEGREES ABOVE
NORMAL THIS WEEKEND AHEAD OF THE COLD FRONT. MIN TEMPS WILL COOL
OFF SOMEWHAT MONDAY NIGHT WITH LOWS IN THE MID TO UPPER 40S ALONG
THE NATURE COAST...MID 50S OVER CENTRAL FLORIDA...AND AROUND 60
OVER SOUTHWEST FLORIDA.
OVERALL...ECMWF IS A TOUCH FASTER THAN GFS THROUGH THE ENTIRE LONG
TERM PERIOD ESPECIALLY WITH THE COLD FRONT LATE THIS WEEKEND. FOR
THE POPS AND TEMPERATURES...WEIGHTED THIS FORECAST PACKAGE MORE
TOWARDS GFS...BUT BLENDED IN THE ECMWF AS WELL TO STAY ON THE SAFE
SIDE.
&&
.AVIATION...
TIMING OF RAIN AND STORMS CONTINUES TO BE A HUGE PROBLEM AS
MODELS ARE STRUGGLING MIGHTILY WITH THE DETAILS OF TODAY`S
FORECAST. TIMING OF MORE SIGNIFICANT PRECIP AND TSTMS ON THE 18Z
TAFS WAS BASED PARTLY ON RADAR TRENDS THE HOUR BEFORE...BUT SINCE
THEN...STORMS HAVE WEAKENED AND DECREASED IN COVERAGE ACROSS THE
NEARSHORE WATERS. MORE AND MORE...IT APPEARS THE MAIN PRECIP/TSTM
EVENT TODAY IS GOING OCCUR WITH THE LAST MAIN S/WV WHICH IS
CURRENTLY GENERATING A SQUALL LINE SOUTH OF MOB. THIS LINE IS
RACING ESE ACROSS THE GULF. WHAT IS LEFT OF THE LINE WILL IMPACT W
AND SW FL ROUGHLY BETWEEN 22 AND 2Z WHICH IS THE TIME FRAME THE
LATEST RAP IS HINTING AT AS WELL. BASED ON THIS WILL BE UPDATING
THE TAFS TO MOVE BACK PRECIP TIMING MORE IN LINE WITH THIS
THINKING. AFTER MVFR CONDITIONS ASSOC W/ THE SHRA AND TSTMS MOVES
OUT OF THE AREA... EXPECT IMPROVING CONDITIONS OVERNIGHT WITH VFR
CONDITIONS DEVELOPING AS COOL AND DRY AIR MOVES INTO THE REGION
BEHIND A COLD FRONT.
&&
.MARINE...
WINDS AND SEAS ARE EXPECTED TO INCREASE TO SCA CONDITIONS ACROSS
THE NORTHERN AND CENTRAL OFFSHORE WATERS BEHIND THE FRONT THIS
EVENING AS HIGH PRESSURE BEGINS TO BUILD INTO THE AREA. HIGH
PRESSURE THEN REMAINS ACROSS THE WATERS THROUGH SATURDAY NIGHT
WITH WINDS DIMINISHING BY MID THURSDAY MORNING. THE NEXT COLD
FRONT WILL THEN PUSH INTO THE AREA FOR SUNDAY WITH WINDS AND SEAS
INCREASING AGAIN JUST AHEAD OF THE FRONT.
&&
.FIRE WEATHER...
COOLER AND DRIER AIR WILL BE MOVING INTO THE AREA BEHIND THE FRONT
TONIGHT ALLOWING FOR SEVERAL HOURS OF CRITICAL HUMIDITIES THURSDAY
AFTERNOON. WINDS SHOULD BE LIGHT AND ERCS LOW ENOUGH TO PREVENT
ANY NEED FOR A RFW OR RFD. MOISTURE WILL BE RETURNING FRIDAY...BUT
A FEW HOURS OF CRITICAL HUMIDITIES WILL STILL BE POSSIBLE. WILL
CONTINUE TO MONITOR ERC VALUES BUT WINDS SHOULD BE LIGHT AGAIN.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 50 67 48 75 / 20 0 0 20
FMY 56 74 52 81 / 20 0 0 20
GIF 50 71 48 78 / 20 0 0 20
SRQ 54 67 48 75 / 20 0 0 20
BKV 41 67 34 77 / 20 0 0 20
SPG 57 66 55 74 / 20 0 0 20
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 10 AM EDT
THURSDAY FOR ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60
NM-TARPON SPRINGS TO SUWANNEE RIVER OUT 20 TO 60 NM.
&&
$$
SHORT TERM/MARINE/FIRE WEATHER...24/COLSON
LONG TERM/AVIATION...88/GITTINGER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
224 PM MDT WED MAR 20 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 224 PM MDT WED MAR 20 2013
19Z WATER VAPOR IMAGERY RUC ANALYSIS INDICATED SHORT WAVE RIDGE
ACROSS NORTHERN PLAINS WITH STRONG TROUGH OVER THE PAC NW. AT THE
SFC...TROUGH WAS DEEPENING OVER EASTERN COLORADO WITH STRONG
SOUTH WINDS DEVELOPING ACROSS MUCH OF THE AREA. THICK CIRRUS HAS
SLOWED WARMING DOWN CONSIDERABLY BUT THINK TEMPS WILL EVENTUALLY
CLIMB INTO LOWER/MID 50S AS WINDS AID IN DEEP LAYER MIXING.
TONIGHT...WEAK SHORT WAVE TROUGH WILL UNDERCUT H5 RIDGE TONIGHT AS
STRONG WAA DEVELOPS TO THE NORTH OF DEVELOPING WARM FRONT ACROSS
NORTHERN CWA. HAVE SOME CONCERNS THAT LIGHT PRECIP MAY CLIP THE
NORTHEASTERN CWA IN AREA OF DEEP WAA...BUT VERTICAL PROFILES APPEAR
TO STABLE TO PRODUCE PRECIPITATION RATES NEEDED TO SATURATE SUB
CLOUD LAYER. PROBABILISTIC DATA SEEMS TO SUPPORT ANY PRECIP THREAT
REMAINING NORTH OF AREA AS WELL SO PLAN ON CONTINUING DRY FORECAST.
WILL HAVE TO WATCH UPSTREAM PRECIP POTENTIAL CLOSELY THOUGH AS WARM
LAYER AOB 3C THROUGH MUCH OF THE NIGHT WHICH WOULD REMOVE ANY ICE
FROM SOUNDING INITIALLY ALLOWING FOR RA/FZRA/IP TO FORM IF PRECIP
WERE TO OCCUR. AS MENTIONED BEFORE THIS REMAINS A VERY LOW
PROBABILITY AT THIS TIME AND IF PRECIP WERE TO OCCUR WET BULB
PROCESSES WOULD COOL WARM LAYER QUICKLY RESULTING IN A FAIRLY SHORT
DURATION.
TOMORROW...A FEW AREAS OF MORNING FOG EXPECTED AS WINDS SHIFT TO THE
EAST IN RESPONSE TO NEXT...MORE SIGNIFICANT SHORT WAVE TROUGH MOVING
INTO THE NORTHERN ROCKIES. THINK WEATHER ACROSS CWA WILL BE FAIRLY
QUIET THROUGH MUCH OF THE DAY...ALTHOUGH PRECIP THREAT WILL BEGIN TO
INCREASE IN THE AFTERNOON AS LARGE SCALE FORCING FOR ASCENT
INCREASES AND CAA ALOFT HELPS DESTABILIZE THINGS. DO NOT THINK
STABILITY PROFILES SUPPORT A THUNDER THREAT ATTM AND PLAN ON KEEPING
PRECIP TYPE AS RAIN THROUGH THE DAY.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 224 PM MDT WED MAR 20 2013
FIRST 500 MB SHORT WAVE WILL MOVE ACROSS THE HIGH PLAINS THURSDAY
NIGHT...THOUGH BEST ENERGY IS PROGGED TO BE NORTH OF THE FORECAST
AREA. INVERTED SURFACE TROUGH WILL PROVIDE LOW LEVEL CONVERGENCE
FROM GOODLAND TO MCCOOK. HOWEVER...MODEL SOUNDINGS SHOW THAT THE
AIR MASS WILL BE SLOW TO SATURATE BELOW 700 MB...ESPECIALLY OVER
THE EASTERN PART OF THE FORECAST AREA. LAYER Q VECTOR CONVERGENCE
IS ALSO NOT PARTICULARLY IMPRESSIVE...THOUGH LOW LEVEL
FRONTOGENESIS IS A LITTLE BETTER FROM 00Z-06Z. BOTTOM LINE ON THIS
FIRST WAVE...WILL CARRY POPS THROUGH 06Z WITH DECREASING CHANCES
AFTERWARDS. MOST PRECIPITATION WILL BE IN THE FORM OF RAIN...THOUGH
COLD AIR WILL EVENTUALLY ADVECT OVER THE AREA AFTER 06Z. AGAIN...THOUGH
...BEST DYNAMICS WILL BE EAST OF THE AREA BY THAT TIME...SO DO
NOT EXPECT MUCH SNOW ACCUMULATION.
THE FIRST SYSTEM WILL MOVE EAST FRIDAY...BUT THE NEXT MORE VIGOROUS
WAVE WILL MOVE OVER EASTERN COLORADO BY FRIDAY AFTERNOON. THIS
SYSTEM IS PROGGED TO HAVE EXCELLENT GEOSTROPHIC PARAMETERS THROUGH
SATURDAY TO PRODUCE WIDESPREAD PRECIPITATION. THE BEST WINDOW FOR
PRECIPITATION WILL OCCUR FROM 09Z SATURDAY THROUGH 03Z SUNDAY. BY
12Z SATURDAY...COLD AIR ADVECTION WILL BE OVER THE ENTIRE AREA...SO
EXPECT PRECIPITATION TYPE TO BE ALL SNOW SATURDAY. PROJECTED SNOW
TOTALS RANGE FROM TWO INCHES SOUTH TO SEVEN INCHES NORTH. THESE
PROJECTIONS ARE IN LINE WITH WINTER SEASON ANALOGS AND WPC ESTIMATES.
MODELS AND OTHER EXTERNAL GUIDANCE HAVE SHOWN DECENT RUN-TO-RUN
CONSISTENCY WITH THIS SYSTEM. NORTH WINDS AT 20 TO 30 KNOTS WILL
DEVELOP SATURDAY PRODUCING AREAS OF BLOWING SNOW.
THE SYSTEM WILL MOVE EAST SUNDAY...BUT WILL KEEP SOME LOW POPS OVER
THE EASTERN THIRD. YET ANOTHER SHORT WAVE TROUGH WILL MOVE OVER THE
HIGH PLAINS SUNDAY NIGHT AND MONDAY BRINGING ANOTHER CHANCE OF
PRECIPITATION. FOR TUESDAY AND WEDNESDAY...MODELS DIVERGE. FOR NOW...
WILL KEEP THE FORECAST DRY.
TEMPERATURES WILL BE SIGNIFICANTLY BELOW NORMAL FRIDAY THROUGH
MONDAY GIVEN ABUNDANT CLOUD COVER...SNOW...AND THE AMOUNT OF COLD
AIR WITH THE SYSTEM. MODELS SHOW WARMING TUESDAY AND WEDNESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1142 AM MDT WED MAR 20 2013
SOUTHERLY WINDS WILL INCREASE TO THE 16-22KT RANGE THROUGH THE
AFTERNOON HOURS FIRST AT GLD AND THEN GRADUALLY EXPANDING TO THE
EAST IMPACTING MCK TO SOME DEGREES AROUND 20Z. WEAK DISTURBANCE
WILL MOVE OVER THE MCK AREA DURING THE EVENING HOURS...BUT
CONFIDENCE IN PRECIPITATION DEVELOPING TOO LOW AT THIS POINT TO
INCLUDE IN TERMINAL BUT GIVEN WARM +3C ALOFT THERE IS POTENTIAL
FOR RA/FZRA SHOULD PRECIP DEVELOP. OTHERWISE WITH WINDS SHIFTING
TO THE EAST AND LOW LEVEL ASCENT LINGERING THROUGH THE MORNING
HOURS...POTENTIAL DOES EXIST FOR MORNING STRATUS AND FOG ALTHOUGH
CURRENT CONFIDENCE LEVELS ARE LOW SO HAVE ONLY INCLUDED MINOR
FLIGHT CATEGORY REDUCTIONS WHERE CONFIDENCE IS HIGHEST.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...MENTZER
AVIATION...JRM
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
259 PM EDT WED MAR 20 2013
.SYNOPSIS...
A WEAK FRONT WILL MOVE THROUGH EASTERN NORTH CAROLINA TONIGHT. HIGH
PRESSURE WILL BUILD IN THURSDAY NIGHT. A SERIES OF WEAK LOW
PRESSURES WILL MOVE THROUGH THE AREA THROUGH THE WEEKEND. A STRONG
SYSTEM WILL MOVE INTO LATE SUNDAY. HIGH PRESSURE WILL BILD IN MONDAY
NIGHT AND REMAIN THROUGH MIDWEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 245 PM WED...UPPER TROUGH OVER THE PLAINS STATES WILL DEEPEN
AND STRONG SHORT WAVE WILL BRING THE BASE OF THE TROUGH THROUGH
NORTH CAROLINA TONIGHT. MODELS IN GOOD AGREEMENT ON TIMING OF THE
FRONT THROUGH THE AREA...ALTHOUGH RUC IS A LITTLE SLOWER. ALSO SOME
DIFFERENCES IN PTYPE...ECMWF PTYPE FIELD IS CALLING IT FROZEN.
HOWEVER FORECAST SOUNDINGS ALL HAVE ABOVE FREEZING NEAR THE
SURFACE...AND HAVE GONE WITH TEMPERATURES IN THE MID TO UPPER 30S
ACROSS THE AREA TONIGHT. PWS A LESS THAN HALF AN INCH AND SOUNDINGS
DONT COMPLETELY SATURATE. SO WILL KEEP ONLY A SLIGHT CHANCE OF
LIQUID SHOWERS TONIGHT WITH LITTLE TO NO QPF.
&&
.SHORT TERM /THURSDAY/...
AS OF 250 PM WED...SHOWERS WILL MOVE OUT DURING THE MORNING HOURS AS
UPPER LEVEL ENERGY SWINGS THROUGH. 8H TEMPERATURES QUITE COOL FOR
THIS TIME OF YEAR...AND WITH ANOTHER PIECE OF ENERGY SWINGING OVER
THE AREA KEEPING THINGS MIXED UP...TEMPERATURES WILL HAVE A HARD
TIME CLIMBING OUT OF THE MIDDLE 40S DURING THE DAY. LOW PRESSURE
WILL DEEPEN AS IT MOVES OFF THE COAST WITH BREEZES REACHING 15 TO 20
MPH.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
AS OF 240 PM WEDNESDAY...COLD CANADIAN HIGH PRESSURE WILL BUILD OVER
THE AREA WITH BELOW FREEZING TEMPS OVER MUCH OF THE AREA LATE THU
NIGHT INTO EARLY FRI MORN AS WINDS DECOUPLE ESPECIALLY AWAY FROM
THE COAST. THERE IS EVEN THE POSSIBILITY THAT WINDS WILL BECOME
LIGHT ALONG THE OBX WITH A FROST OR FREEZING TEMPERATURES. SINCE
THE SPRING GROWING SEASON HAS ALREADY BEGUN FOR THE OBX...AND
BEGAN TODAY FOR CARTERET AND ONSLOW COUNTIES HAVE ISSUED A FREEZE
WATCH FOR LATE THU NIGHT INTO EARLY FRI MORN FOR THESE AREAS.
UPPER ENERGY WILL MOVE INTO THE FOUR CORNERS REGION WITH
DEVELOPMENT OF A SURFACE LOW LATE FRIDAY. LOW PRESSURE WILL
DEEPEN AS IT MOVES EAST INTO THE MID MISSISSIPPI VALLEY BY EARLY
SUNDAY. ANOTHER SURFACE LOW WILL DEVELOP OVER THE NORTH CENTRAL
GULF OF MEXICO. THIS LOW WILL MOVE UP THE CAROLINA COAST DEEPENING
AS IT MOVES AWAY FROM THE REGION LATE MONDAY. ECMWF NOT AS STRONG
WITH THE DEEPENING AS THE GFS.
WILL CONT WITH LOW POPS FOR THE SOUTHERN COUNTIES FRIDAY
NIGHT/SATURDAY AHEAD OF AN UPR LVL IMPL THEN HIGH CHANCE POPS FOR
SUNDAY AND SUNDAY NIGHT AS THE LOW MOVES UP THE COAST WITH GOOD
LOW LEVEL MOISTURE ADVECTION SPLY ON SUNDAY. MODELS CONT TO SHOW SOME
INSTABILITY NEAR THE COAST ON SUNDAY SO WILL KEEP A SLIGHT CHANCE
OF TSTMS AS WELL.
COOLER THAN NORMAL TEMPS EXPECTED IN THE LONG TERM WITH LOWER 500
MB HEIGHTS CONTINUING. COLDEST TEMPS EXPECTED ON THU NIGHT FRI
MORN FROM THE MID 20S WELL INLAND TO THE LOWER AND MID 30S OBX.
FOR THE REMNDR OF THE LONG TERM PERIOD HIGHS WILL BE IN THE 50S
AND LOWS FROM THE MID 30S INLAND TO THE LWR 40S ON THE COAST.
&&
.AVIATION /18Z WEDNESDAY NIGHT THROUGH SUNDAY/...
SHORT TERM /THROUGH THURSDAY AFTERNOON/...
AS OF 125 PM WED...VFR CONDITIONS EXPECTED THROUGH THE TAF
PERIOD. SOME MID/HIGH CLOUDS ARE STREAMING INTO EASTERN NC FROM
THE SOUTHWEST AHEAD OF A DEVELOPING LOW PRESSURE SYSTEM PROGGED TO
MOVE WELL OFFSHORE. ANTICIPATE CLOUD COVER TO CONTINUE THROUGH
MUCH OF THIS AFTERNOON/EVENING. BRIEF CLEARING IS ANTICIPATED AS
THE SYSTEM MOVES FURTHER OUT TO SEA. HOWEVER..SOME MID LEVEL
CLOUDS ASSOCIATED WITH AN UPPER LEVEL TROUGH WILL PIVOT ACROSS THE
AREA TOMORROW EARLY MORNING. PRECIPITATION WITH THIS SYSTEM SEEMS
MINIMAL AT THIS TIME. WINDS WILL BE VARIABLE THROUGH THE
OVERNIGHT. HOWEVER...AS THE UPPER LEVEL TROUGH MIGRATES OVERHEAD
AND THE STRONG LOW PRESSURE SYSTEM CONTINUES TO MOVE OUT TO
SEA...GUSTY NW WINDS WILL DEVELOP.
LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 240 PM WEDNESDAY...SHOULD SEE GENERALLY VFR CONDITIONS
THURSDAY AND FRIDAY AS COOL CANADIAN HIGH PRESSURE DOMINATES.
MOISTURE RETURNS DURING THE WEEKEND AS LOW PRESSURE MOVES UP THE
NC COAST. EXPECT SUB VFR CONDS IN SHOWERS...ESPECIALLY ON SUNDAY.
&&
.MARINE...
SHORT TERM /THROUGH THURSDAY/...
AS OF 255 PM WED...NORTHEAST WIND OVER THE WATESR THIS AFTERNOON
RUNNING 10 TO 15 KNOTS WITH SEAS 2 TO 3 FEET. AN UPPER LEVEL TROUGH
WILL MOVE THROUGH THE AREA TONIGHT...PUSHING A COLD FRONT THROUGH
THE WATERS AROUND SUNRISE. WINDS AHEAD OF THE FRONT WILL TURN FROM
NORTHEAST TO SOUTHEAST AND THEN SOUTHWEST...THEN BECOME NORTHWEST
AGAIN BEHIND THE FRONT. AS LOW PRESSURE MOVES OFF SHORE IT WILL
START TO DEEPEN...TIGHTENING GRADIENT OVER THE NC COASTAL WATESR
DURING THE AFTERNOON. WIND AND SEAS WILL REACH SCA CRITERIA DURING
THE LATE AFTERNOON HOURS.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
AS OF 240 PM THURSDAY...NORTHWEST WINDS BEHIND SHORTWAVE SHOULD
CONTINUE IN THE 20 TO 25 KNOT RANGE ACROSS THE NRN AND CNTRL
COASTAL WATERS THROUGH ABOUT 06Z WITH SEAS BUILDING INTO THE 4-7
FT RANGE. SCA HAS BEEN ISSUED FOR THIS AREA. WEAK HIGH PRES WILL
RESULT IN THE WINDS AT 15 KNOTS OR LESS AND SEAS AT 4 FEET OR LESS
FRIDAY AND SATURDAY. LOW PRESSURE THEN MOVES UP THE COAST WITH E
TO NE WINDS INCREASING SUNDAY THEN GUSTY WEST WINDS FOLLOW ON THE
BACKSIDE OF THE LOW ON MONDAY. SEAS ARE EXPECTED TO BE IN THE 4-7
FOOT RANGE FOR SUNDAY AND MONDAY.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...FREEZE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING
FOR NCZ095-098-103-104.
MARINE...SMALL CRAFT ADVISORY FROM 1 PM THURSDAY TO 2 AM EDT FRIDAY FOR
AMZ150-152-154.
&&
$$
SYNOPSIS...CGG
NEAR TERM...CGG
SHORT TERM...CGG
LONG TERM...JAC
AVIATION...JAC/LEP
MARINE...CGG/JAC
...CORRECT TYPO IN THE AVIATION FORECAST DISCUSSION.
.SHORT TERM...TONIGHT AND THURSDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A BROAD AND
ELONGATED UPPER LEVEL LOW PRESSURE SYSTEM SPINNING FROM THE CENTRAL
GREAT LAKES TO NEW ENGLAND EARLY THIS AFTERNOON. CLOUDS HAVE BEEN
SPREADING SOUTH ACROSS THE UPPER PENINSULA AND NORTHERN WISCONSIN SO
FAR TODAY...AS A RESULT OF SHORTWAVE LOBES ROTATING AROUND THE
PARENT VORTEX...AND ALSO STEEPENING LOW LEVEL LAPSE RATES. THESE
CONDITIONS ALSO PROMOTE CONDITIONS FOR SIGNIFICANT LAKE EFFECT
SNOWS...WHICH ARE OCCURRING WITHIN THE SNOW BELTS OF THE WESTERN
UPPER PENINSULA. IN FACT...IRONWOOD HAS OSCILLATED BETWEEN 1/2SM
AND 3/4SM FOR MUCH OF THE DAY. LAKE EFFECT POTENTIAL IS THE MAIN
FORECAST CONCERN OVER THE NEXT 24 HOURS AS WIND TRAJECTORIES BECOME
MORE FAVORABLE FOR N-C WISCONSIN.
TONIGHT...SHORTWAVE TROUGH WILL DIVE SOUTH ACROSS CENTRAL AND
SOUTHERN WISCONSIN THIS EVENING...ON THE WESTERN FLANK OF THE UPPER
LOW. NOT SOLD THAT PRECIP WILL TURN OFF AT SUNSET...THOUGH DIURNAL
INSTABILITY WILL BE LOST. WILL KEEP LIGHT SNOW SHOWERS AND FLURRIES
GOING FOR A GOOD CHUNK OF THE EVENING. BEHIND THE SHORTWAVE...LOW
LEVEL WINDS TURN TO THE NNW. WIND TRAJECTORIES LOOK REALLY GOOD FOR
A SOLID LAKE EFFECT EVENT FOR N-C WISCONSIN. THERMAL PROFILES ARE
ALSO IN THE OPTIMAL DENDRITIC GROWTH ZONE THROUGH THE NIGHT...AND
THERE IS SUFFICIENT MOISTURE IN THE 850-700MB LAYER AS WELL. ON THE
MINUS SIDE...SUBSIDENCE WILL BE INCREASING THROUGH THE NIGHT AND
LAKE INDUCED CAPE WILL GRADUALLY DIMINISH. THE LOCAL LAKE EFFECT
PARAMETER DOES SHOW A SLIGHT DIMINISHING TREND TONIGHT...BUT NOT
THAT SIGNIFICANT. A LIMITING FACTOR MAY BE THE 15 KT BL WINDS...IN
WHICH THE NORTHERN PART OF VILAS COUNTY GETS ADVISORY CRITERIA
SNOW...AND THE SOUTHERN HALF DOES NOT. SO THINK WILL GO WITHOUT AN
ADVISORY AND ISSUE AN SPS FOR THE COUNTY TONIGHT...AND WILL
HIGHLIGHT THAT SEVERAL INCHES OF SNOW ARE POSSIBLE ACROSS THE
NORTHERN PART OF THE COUNTY. PARTIAL CLEARING SHOULD OCCUR OUTSIDE
THE LAKE EFFECT BELT DURING THE OVERNIGHT HOURS...BUT DO NOT THINK
WILL SEE DECOUPLING. AS A RESULT...LOW TEMPS WILL BE COMPARABLE TO
LAST NIGHTS LOWS.
THURSDAY...LAKE EFFECT SNOW SHOWERS WILL CONTINUE OVER N-C WISCONSIN
THROUGH EARLY AFTERNOON...BUT SHOULD DIMINISH AS DRY AIR INVADES
FROM THE NORTH. ELSEWHERE...AFTER A MOSTLY CLEAR TO PARTLY CLOUDY
START TO THE DAY...CLOUDS SHOULD BE INCREASING BY LATE MORNING OR
EARLY AFTERNOON AS WILL STILL HAVE PLENTY OF LOW LEVEL MOISTURE AND
STEEP LOW LEVEL LAPSE RATES AROUND. INCREASED CLOUD COVER...BUT
KEPT THE SNOW CHANCES CONFINED TO THE SNOW BELT. HIGHS SEVERAL
DEGREES WARMER THAN TODAY WITH HIGHS MAINLY IN THE MID TO UPPER 20S.
.LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY...MAIN FCST
CONCERN IS TEMPERATURES.
A LARGE UPPER LEVEL LOW WILL RESIDE OVER EASTERN CANADA AND THE
EASTERN GREAT LAKES REGION EARLY IN THE PERIOD...BUT WILL SHIFT
EAST BY FRI/SAT...ALLOWING WEAK RIDGING TO DEVELOP OVER WI. A
LARGE CANADIAN SFC HIGH WILL RIDGE INTO THE WESTERN GREAT LAKES
DURING THIS PERIOD...BRINGING DRY...BUT CONTINUED COOL CONDITIONS.
WITH LOW-LEVEL WINDS TURNING NNE-NE...CONSIDERED THE POSSIBILITY
OF SOME LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES IN EASTERN WI...
BUT WINDS ARE VERY LIGHT ON FRIDAY NIGHT...AND MOISTURE AND
INSTABILITY ARE NOT VERY FAVORABLE ON SATURDAY...SO KEPT A DRY
FCST INTACT.
THE UPPER PATTERN WILL TRANSITION BACK TO A BROAD UPPER TROF LATE
IN THE WEEKEND...AND CONTINUING THROUGH THE MIDDLE OF NEXT WEEK.
THE ONLY SIGNIFICANT STORM OF THE WEEK IS A LOW PRESSURE SYSTEM
WHICH MOVES THROUGH THE SOUTHERN PLAINS ON SATURDAY...THEN LIFTS
NE THROUGH THE TENNESSEE VALLEY AND INTO THE MID-ATLANTIC STATES
BY MONDAY. THIS STORM SHOULD PASS FAR ENOUGH SOUTH AND EAST OF THE
REGION TO PREVENT ANY SIGNIFICANT PCPN DEVELOPMENT OVER C/NE WI.
HOWEVER...LOW-LEVEL CYCLONIC FLOW AND THE PRESENCE OF THE BROAD
UPPER TROF COULD BRING SCT LIGHT SNOW SHOWERS OR FLURRIES AT
TIMES. FOR NOW...WILL MAINLY BE CARRYING SLIGHT CHC POPS FROM THE
LATE WEEKEND THROUGH MIDWEEK.
H8 TEMPS WILL NOT VARY MUCH OVER THE PERIOD...WITH MOST OF THE
MEDIUM RANGE MODELS FORECASTING -8 TO -12 C. THIS SHOULD CONTINUE
THE TREND OF BELOW NORMAL TEMPERATURES FOR THE NEXT WEEK...WITH
LOWS IN THE TEENS AND LOWER 20S...AND HIGHS IN THE 30S.
&&
.AVIATION...BKN TO OVC MVFR DECK TO DEVELOP ACROSS MUCH OF CENTRAL
AND NORTH-CENTRAL WISCONSIN EARLY THIS AFTERNOON. SKY CONDITIONS TO
TURN BKN AND OVC OVER NE WISCONSIN AS WELL...BUT ONLY SLIGHTLY
HIGHER THAN MVFR. BEST CHANCE OF SNOW SHOWERS TO OCCUR MID
AFTERNOON TO EARLY THIS EVENING...AND SOME POTENTIAL THAT VSBYS
COULD DROP TO IFR IN THE SNOW SHOWERS. NNW WINDS TO KEEP LAKE
EFFECT SNOW SHOWERS WITHIN THE SNOW BELTS OF N-C WISCONSIN TONIGHT
WHERE A FEW INCHES OF ACCUMULATION IS POSSIBLE. SKIES TO PARTIALLY
CLEAR EVERYWHERE ELSE. CLOUDS WILL THEN REDEVELOP BY LATE TOMORROW
MORNING ACROSS THE REGION.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/KIECKBUSCH
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
233 PM CDT WED MAR 20 2013
.SHORT TERM...TONIGHT AND THURSDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A BROAD AND
ELONGATED UPPER LEVEL LOW PRESSURE SYSTEM SPINNING FROM THE CENTRAL
GREAT LAKES TO NEW ENGLAND EARLY THIS AFTERNOON. CLOUDS HAVE BEEN
SPREADING SOUTH ACROSS THE UPPER PENINSULA AND NORTHERN WISCONSIN SO
FAR TODAY...AS A RESULT OF SHORTWAVE LOBES ROTATING AROUND THE
PARENT VORTEX...AND ALSO STEEPENING LOW LEVEL LAPSE RATES. THESE
CONDITIONS ALSO PROMOTE CONDITIONS FOR SIGNIFICANT LAKE EFFECT
SNOWS...WHICH ARE OCCURRING WITHIN THE SNOW BELTS OF THE WESTERN
UPPER PENINSULA. IN FACT...IRONWOOD HAS OSCILLATED BETWEEN 1/2SM
AND 3/4SM FOR MUCH OF THE DAY. LAKE EFFECT POTENTIAL IS THE MAIN
FORECAST CONCERN OVER THE NEXT 24 HOURS AS WIND TRAJECTORIES BECOME
MORE FAVORABLE FOR N-C WISCONSIN.
TONIGHT...SHORTWAVE TROUGH WILL DIVE SOUTH ACROSS CENTRAL AND
SOUTHERN WISCONSIN THIS EVENING...ON THE WESTERN FLANK OF THE UPPER
LOW. NOT SOLD THAT PRECIP WILL TURN OFF AT SUNSET...THOUGH DIURNAL
INSTABILITY WILL BE LOST. WILL KEEP LIGHT SNOW SHOWERS AND FLURRIES
GOING FOR A GOOD CHUNK OF THE EVENING. BEHIND THE SHORTWAVE...LOW
LEVEL WINDS TURN TO THE NNW. WIND TRAJECTORIES LOOK REALLY GOOD FOR
A SOLID LAKE EFFECT EVENT FOR N-C WISCONSIN. THERMAL PROFILES ARE
ALSO IN THE OPTIMAL DENDRITIC GROWTH ZONE THROUGH THE NIGHT...AND
THERE IS SUFFICIENT MOISTURE IN THE 850-700MB LAYER AS WELL. ON THE
MINUS SIDE...SUBSIDENCE WILL BE INCREASING THROUGH THE NIGHT AND
LAKE INDUCED CAPE WILL GRADUALLY DIMINISH. THE LOCAL LAKE EFFECT
PARAMETER DOES SHOW A SLIGHT DIMINISHING TREND TONIGHT...BUT NOT
THAT SIGNIFICANT. A LIMITING FACTOR MAY BE THE 15 KT BL WINDS...IN
WHICH THE NORTHERN PART OF VILAS COUNTY GETS ADVISORY CRITERIA
SNOW...AND THE SOUTHERN HALF DOES NOT. SO THINK WILL GO WITHOUT AN
ADVISORY AND ISSUE AN SPS FOR THE COUNTY TONIGHT...AND WILL
HIGHLIGHT THAT SEVERAL INCHES OF SNOW ARE POSSIBLE ACROSS THE
NORTHERN PART OF THE COUNTY. PARTIAL CLEARING SHOULD OCCUR OUTSIDE
THE LAKE EFFECT BELT DURING THE OVERNIGHT HOURS...BUT DO NOT THINK
WILL SEE DECOUPLING. AS A RESULT...LOW TEMPS WILL BE COMPARABLE TO
LAST NIGHTS LOWS.
THURSDAY...LAKE EFFECT SNOW SHOWERS WILL CONTINUE OVER N-C WISCONSIN
THROUGH EARLY AFTERNOON...BUT SHOULD DIMINISH AS DRY AIR INVADES
FROM THE NORTH. ELSEWHERE...AFTER A MOSTLY CLEAR TO PARTLY CLOUDY
START TO THE DAY...CLOUDS SHOULD BE INCREASING BY LATE MORNING OR
EARLY AFTERNOON AS WILL STILL HAVE PLENTY OF LOW LEVEL MOISTURE AND
STEEP LOW LEVEL LAPSE RATES AROUND. INCREASED CLOUD COVER...BUT
KEPT THE SNOW CHANCES CONFINED TO THE SNOW BELT. HIGHS SEVERAL
DEGREES WARMER THAN TODAY WITH HIGHS MAINLY IN THE MID TO UPPER 20S.
.LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY...MAIN FCST
CONCERN IS TEMPERATURES.
A LARGE UPPER LEVEL LOW WILL RESIDE OVER EASTERN CANADA AND THE
EASTERN GREAT LAKES REGION EARLY IN THE PERIOD...BUT WILL SHIFT
EAST BY FRI/SAT...ALLOWING WEAK RIDGING TO DEVELOP OVER WI. A
LARGE CANADIAN SFC HIGH WILL RIDGE INTO THE WESTERN GREAT LAKES
DURING THIS PERIOD...BRINGING DRY...BUT CONTINUED COOL CONDITIONS.
WITH LOW-LEVEL WINDS TURNING NNE-NE...CONSIDERED THE POSSIBILITY
OF SOME LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES IN EASTERN WI...
BUT WINDS ARE VERY LIGHT ON FRIDAY NIGHT...AND MOISTURE AND
INSTABILITY ARE NOT VERY FAVORABLE ON SATURDAY...SO KEPT A DRY
FCST INTACT.
THE UPPER PATTERN WILL TRANSITION BACK TO A BROAD UPPER TROF LATE
IN THE WEEKEND...AND CONTINUING THROUGH THE MIDDLE OF NEXT WEEK.
THE ONLY SIGNIFICANT STORM OF THE WEEK IS A LOW PRESSURE SYSTEM
WHICH MOVES THROUGH THE SOUTHERN PLAINS ON SATURDAY...THEN LIFTS
NE THROUGH THE TENNESSEE VALLEY AND INTO THE MID-ATLANTIC STATES
BY MONDAY. THIS STORM SHOULD PASS FAR ENOUGH SOUTH AND EAST OF THE
REGION TO PREVENT ANY SIGNIFICANT PCPN DEVELOPMENT OVER C/NE WI.
HOWEVER...LOW-LEVEL CYCLONIC FLOW AND THE PRESENCE OF THE BROAD
UPPER TROF COULD BRING SCT LIGHT SNOW SHOWERS OR FLURRIES AT
TIMES. FOR NOW...WILL MAINLY BE CARRYING SLIGHT CHC POPS FROM THE
LATE WEEKEND THROUGH MIDWEEK.
H8 TEMPS WILL NOT VARY MUCH OVER THE PERIOD...WITH MOST OF THE
MEDIUM RANGE MODELS FORECASTING -8 TO -12 C. THIS SHOULD CONTINUE
THE TREND OF BELOW NORMAL TEMPERATURES FOR THE NEXT WEEK...WITH
LOWS IN THE TEENS AND LOWER 20S...AND HIGHS IN THE 30S.
&&
.AVIATION...M000 TO 3000 FT CIGS AND A FEW SNOW FLURRIES NEAR THE
MICHIGAN BORDER WILL TRY TO MOVE SOUTH A LITTLE BUT MOST PLACES
WILL BE CLEAR TONIGHT. COLD AIR ALOFT WILL GENERATE MVFR CIGS AND
SNOW SHOWERS WEDNESDAY AS AN UPPER LEVEL LOW MOVES SOUTH TOWARDS
THE REGION.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/KIECKBUSCH