Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/03/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1001 PM MST THU FEB 28 2013
.UPDATE...
&&
.SHORT TERM...SWIFT NORTH-NORTHWEST FLOW ALOFT IN PLACE. A WEAK
UPPER AIR PERTURBATION IN THIS FLOW CURRENTLY PASSING OVER COLORADO.
DISTURBANCE WAS GENERATING ONLY WEAK MID/UPPER LEVEL QG ASCENT.
CLOUD COVER AND LIGHT SNOWFALL IN THE NORTHERN MOUNTAINS PRINCIPALLY
THE PRODUCT OF OROGRAPHICS...I.E. NORTHERLY UPSLOPE FLOW. 1 TO 3
INCH SNOW ACCUMULATIONS STILL LOOKS GOOD FOR THE NORTHERN MTNS
OVERNIGHT. 25-40KTS NWLY WINDS ON THE MTN TOPS AND HIGH PASSES ALSO
PRODUCING AREAS OF BLOWING/DRIFTING SNOW. LIKELY WE/LL SEE THIS
CONTINUE IN THESE HIGH TERRAIN AREAS REST OF TONIGHT AS WINDS ALOFT
ASSUME MORE OF A NORTHERLY COMPONENT. EAST OF THE MOUNTAINS...SNOW
CHANCES PRETTY MUCH OVER...EXCEPT PERHAPS ALONG THE PALMER DIVIDE IN
ELBERT AND NORTHERN LINCOLN COUNTIES...OUT ACROSS ERN PORTIONS OFF
ADAMS AND ARAPAHOE COUNTIES AND SOUTHERN WASHINGTON OVER THE NEXT 2-
4 HRS. NO ACCUMULATION AND ANY SNOWFALL WILL BE QUITE LIGHT AS SUB-
CLOUD LAYER IS QUITE DRY. COUNTING ON CLEARING UP ALONG THE WYOMING
BORDER AFTER MIDNIGHT...WITH PARTIAL CLEARING ALONG THE FRONT RANGE
BEFORE MORNING LIGHT.
.AVIATION...VFR CONDITIONS TO CONTINUE IN THE DENVER METRO AREA
NEXT 24 HOURS. SNOW CHANCES ALMOST NIL REST OF TONIGHT. SOUTH-
SOUTHEAST WINDS OF 5-12KTS IN THE DENVER METRO AREA MAY GO
NORTHWESTERLY 5-10KTS FOR A TIME AROUND MIDNIGHT WITH OUTFLOW FROM
THE LAST OF THE SNOW SHOWERS ON THE HIGH FOOTHILLS. SKIES SHOULD
PARTIALLY CLEAR OVER THE METRO AREA DURING THE PRE-DAWN HOURS.
&&
.PREV DISCUSSION... /ISSUED 349 PM MST THU FEB 28 2013/
SHORT TERM...MOISTURE CONTINUES TO INCREASE ACROSS MOUNTAINS AS
DISTURBANCE BEGINS TO MOVE INTO WESTERN COLORADO. MODERATE
NORTHWEST FLOW ALOFT PROVIDING DECENT OROGRAPHICS WITH OROGRAPHICS
AROUND 6 C/KM. MOUNTAIN WEB CAMS SHOWING SNOW SHOWERS BECOMING
MORE WIDESPREAD...MAINLY ALONG CONTINENTAL DIVIDE OF SUMMIT AND
GRAND COUNTIES AS WELL AS PARK AND GORE RANGES OF WESTERN JACKSON
COUNTY. SO FAR... ACCUMULATIONS MINIMAL BASED ON LATEST SNOTEL
DATA. WINDS HAVE BEEN GUSTY OVER THE HIGHER MOUNTAINS AND ALONG
FOOTHILLS AS WELL AS ACROSS SOUTH PARK. DISTURBANCE TO MOVE ACROSS
MOUNTAINS AND PLAINS THROUGH THE EVENING. LATEST RAP AND NAM QG
VERTICAL VELOCITY PROGS STILL INDICATING ASCENT TO BE MINIMAL...SO
MOUNTAIN SNOWFALL TO BE MAINLY OROGRAPHICALLY DRIVEN WITH SOME
HELP WITH INSTABILITY. ACCUMULATIONS OF 1 TO 4 INCHES STILL
LOOKING ON TRACK THOUGH SOME LOCATIONS ALONG THE FAVORED WEST AND
NORTHWEST ASPECTS COULD RECEIVE A COUPLE EXTRA INCHES. NORTHWEST
FLOW TO PROVIDE DOWNSLOPE IN AND NEAR FOOTHILLS SO SNOW SHOWERS
THERE WILL BE LIMITED. BUT THERE WILL BE SOME WIND GUSTS TO 50 MPH
DUE TO THE DOWNSLOPE. ACROSS PLAINS... SOUTHEAST WINDS DEVELOPED
IN THE DENVER AREA DUE TO WEAK ANTICYCLONE OVER SOUTHERN WELD
COUNTY. LATEST MODELS SHOWING THIS ANTICYCLONE SHIFTING EAST OF
THE DENVER AREA DURING THE EVENING AS DOWNSLOPE OFF FOOTHILLS
BEGINS TO DOMINATE FRONT RANGE. STILL THINKING THIS DOWNSLOPE FLOW
WILL LIMIT SNOW CHANCES ALONG URBAN CORRIDOR. MODELS STILL SHOWING
BEST CHANCE FOR SHOWERS TO BE EAST AND SOUTH OF DENVER...PAINTING
SOME LIGHT QPF AND SNOW ACCUMULATIONS. WILL UP THE POPS TO THE
CHANCE CATEGORY IN THIS AREA...KEEPING REST OF THE POPS AS IS.
LATEST CROSS SECTIONS INDICATE A GRADUAL DECREASE IN MOISTURE
AFTER MIDNIGHT. STILL GOOD OROGRAPHICS FOR CONTINUED MOUNTAIN SNOW
SHOWERS. CLOUD COVER AND WIND TO HELP MODERATE OVERNIGHT
TEMPERATURES. ON FRIDAY...FLOW ALOFT BECOMES A BIT MORE NORTHERLY
AS TROUGH MOVES INTO CENTRAL PLAINS. MOISTURE OVER MOUNTAINS
CONTINUES TO DRY OUT. OROGRAPHICS STILL FAVORABLE FOR MOUNTAIN
SNOW SHOWERS...THOUGH INCREASING STABILITY AND LACK OF LIFT WILL
LIMIT COVERAGE. PERHAPS ANOTHER INCH OR SO OF ACCUMULATION. ACROSS
PLAINS...SOME MID AND HIGH LEVEL CLOUDS TO PREVAIL. AIRMASS TO
WARM SLIGHTLY...SHOULD ALLOW TEMPERATURES TO WARM INTO THE 40S
ACROSS THE PLAINS...THOUGH SNOW COVER COULD KEEP TEMPERATURES IN
THE 30S. WINDS TO BE A BIT GUSTY ACROSS HIGHER RIDGES AND FAR
EASTERN PLAINS.
LONG TERM...THE CWA WILL BE UNDER FAIRLY STRONG NORTHERLY FLOW
ALOFT BY FRIDAY EVENING AS A VERY FAST MOVING SHORT WAVE TROUGH
WHICH CLIPS THE HIGH PLAINS STATES EARLY FRIDAY MOVES OUT OF THE
AREA. THE 12Z NAM INDICATES A SECOND BUT VERY MINOR DISTURBANCE IN
THE NORTHERLY FLOW WHICH PROVIDES ADDITIONAL BUT SCANT MOISTURE TO
THE HIGH COUNTRY ALONG WITH ANOTHER PUSH OF STRONG NORTHWEST WINDS
ACROSS THE NORTHEAST PLAINS LATE FRIDAY INTO EARLY SATURDAY. DRY
DOWNSLOPE LOOKS TO BE THE RULE ONCE AGAIN WITH NO POPS EXPECTEDAT
LOWER ELEVATIONS. IN THE HIGH COUNTRY...CROSS SECTIONS CONTINUE TO
SHOW SHALLOW MOISTURE BEING HELD AGAINST THE DIVIDE WITH
OROGRAPHICS DOING THE ONLY LIFTING FOR ANY SNOW SHOWERS. GFS-QG
FIELDS INDICATE NEUTRAL TO SLIGHT DOWNWARD MOTION FRIDAY EVE
THROUGH LATE SATURDAY AND SEE NO REASON TO BUMP THE POPS OVER THE
ISOLD SNOW SHOWERS CURRENTLY IN THE ZFP. BY MIDDAY/EVE SATURDAY
THE AMPLIFIED RIDGE OF HIGH PRESSURE WITH AN AXIS LOCATED OVER THE
EASTERN EDGE OF THE GREAT BASIN IS ALREADY WEAKENING OUT AHEAD OF
THE NEXT DISTURBANCE EXPECTED FOR THE NORTHERN COLO EARLY SUNDAY.
AS THE WEAKENING RIDGE MOVES OUT OVER THE CENTRAL US...TIGHT
PACKING IN THE MID/UPPER LEVEL HEIGHT FIELDS PROVIDES FOR SOME
BRIEF BUT STRONG WESTERLY FLOW ACROSS THE STATE ON SUNDAY.
SANGSTER HIGH WIND MODEL INDICATES POTENTIAL HIGH WIND CRITERIA
BEING MET FOR THE SUNDAY AFT/EVE. WILL BUMP UP WIND GRIDS FOR THIS
NOTIFICATION AND SHD BE WATCHED IN LATER RUNS. AFTER THIS
INFLECTION POINT IN THE FLOW ALOFT...LATEST GFS/CMC TRAJECTORY
WITH THIS NEXT FAST MOVING WAVE TAKES UPPER LOW OVER WESTERN MT
SOUTHEASTWARD OVER THE BLACK HILLS REGION OF SD AND INTO EAST CENT
NE BY MONDAY NIGHT. THIS WILL DO MUCH LIKE THE PREVIOUS WAVES
GIVING A BRIEF SHOT OF LIGHT SNOW TO THE NORTHERN AND CENT MTNS
WHILE PRODUCING DRY NORTHWEST DOWNSLOPE FLOW EAST OF THE DIVIDE.
ECM IS SLOWER WITH THE FEATURE BUT DRYER AND MORE NORTHERLY.
HOWEVER...HAVE ADJUSTED POP GRIDS AROUND THIS SUNDAY INTO EARLY
MONDAY TIME FRAME FOR THE MTN LOCATIONS FOR A LONGER PERIOD OF
LIGHT SNOW ASSOC WITH TROUGH.
LOOKING TOWARD THE TUESDAY THROUGH THURSDAY PERIOD...A WARM
STABLE RIDGE OF HIGH PRESSURE WILL CONTINUE TO DEVELOP OVER THE
WESTERN US WHILE MAXIMIZING IN THE TUESDAY EVENING TO EARLY
WEDNESDAY TIMEFRAME. WILL EXPECT TUE TO REMAIN COOL AND BREEZY IN
THE MORNING POST TROUGH THEN GOOD WARMING INTO TUESDAY AFTN AND THE
DAYS AHEAD. THIS RIDGE WILL LIKELY TAKE DAYTIME HIGHS WELL ABOVE
SEASONAL NORMALS AT LOWER ELEVATIONS FOR BOTH WED AND THURS AS
WARMER SOUTHWESTERLY FLOW ALOFT PREVAILS BOTH DAYS IN ADVANCE OF THE
NEXT LARGER AND COLDER WAVE BEYOND THURSDAY.
AVIATION...WEAK ANTICYCLONE NORTH OF DENVER...WITH SOUTHEAST
WINDS AT KDEN WHILE DOWNSLOPE WESTERLIES PREVAILING AT KBJC AND
KAPA. ANTICYCLONE EXPECTED TO MOVE SOUTHEAST OF DENVER DURING THE
EVENING...WITH WINDS SHIFTING TO THE NORTHWEST AT KDEN. CEILINGS
TO LOWER DURING THE EVENING...SHOULD REMAIN ABOVE 10000 FEET WITH
VFR CONDITIONS PREVAILING. SLIGHT CHANCE OF SNOW SHOWERS THIS
EVENING AS DISTURBANCE MOVES ACROSS. STILL THINKING THE BEST
CHANCE FOR SHOWERS WILL BE SOUTHEAST OF DENVER AS THE DOWNSLOPE
WIND SHOULD LIMIT THE SHOWERS. IF A SHOWER DOES OCCUR...IT SHOULD
BE LIGHT AND BRIEF WITH LITTLE OR NO ACCUMULATION. CEILINGS OF
AROUND 6000 FEET AGL COULD ACCOMPANY THE SHOWERS. FOR NOW WILL
LEAVE OUT OF THE TAFS. AFTER MIDNIGHT... WINDS TO SHIFT TO SOUTH
SOUTHWEST AS DRAINAGE DEVELOPS. SOUTHERLY WINDS TO PREVAIL THROUGH
THE DAY FRIDAY WITH SPEEDS LESS THAN 8 KTS. VFR TO CONTINUE.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BAKER
LONG TERM....FREDIN
AVIATION...BAKER
AREA FORECAST DISCUSSION
NWS ALBANY NY
1245 AM EST FRI MAR 1 2013
.SYNOPSIS...
LOW PRESSURE WILL CONTINUE TO MOVE VERY SLOWLY OVER NEW YORK AND NEW
ENGLAND OVERNIGHT INTO FRIDAY. THE UPPER LOW WILL BRING CLOUDY
CONDITIONS AND NUISANCE LIGHT RAIN OR SNOW SHOWERS INTO THE WEEKEND.
TEMPERATURES WILL RUN SLIGHTLY ABOVE NORMAL THROUGH THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 1245 AM EST...RADAR INDICATED THAT LIGHT PRECIPITATION HAS
FLARED UP IN THE HUDSON VALLEY...IN THE CAPITAL DISTRICT AND POINTS
NORTHWARD. LOOKS TO BE TIED INTO THE TERRAIN...BUT IRONICALLY AT
THIS TIME...LESS GOING ON ACROSS THE HIGHER TERRAIN THAN IN THE
MOHAWK VALLEY. MIGHT BE A FORM OF MOHAWK HUDSON CONVERGENCE SINCE
THE WIND HAS WEST IN THE MOHAWK VALLEY...NW AT KALB AND MORE
NORTHERLY AT KGFL. WHILE CERTAINLY NOT A PURE CASE...THERE IS
CLEARLY SOME SORT OF ENHANCEMENT IN OUR AREA.
THE LATEST NAM AND HRRR ACTUALLY INDICATED THIS ENHANCEMENT TO
HAPPEN. FOLLOWING IT CUE...AS THE CENTER OF THE UPPER AIR LOW LIFTS
A LITTLE NORTHEAST...SOMEWHAT DRIER SHOULD MOVE IN FROM THE SOUTH...
LIMITING ADDITIONAL SHOWERS BY PROBABLY UNTIL AFTER DAWN.
FOR THIS UPDATED...INCREASED POPS TO LIKELY ACROSS THE CAPITAL
DISTRICT FOR A FEW HOURS OVERNIGHT...SCATTERED MOST OTHER
PLACES...EXCEPT ISOLATED MID HUDSON VALLEY AND LOWER LITCHFIELD.
STILL WARM ENOUGH IN THE LOWEST LEVELS FOR THIS TO BE RAIN...AT
LEAST IN THE VALLEYS. THE FREEZING LAYER LOOKS TO BE AROUND 1500
FEET...MAYBE DROPPING A LITTLE BY DAWN. RAIN SHOWERS COULD CERTAINLY
MIX WITH WET SNOW FLAKES BY DAWN WITH NO ACCUMULATIONS EXPECTED.
HIGHER TERRAIN SURROUNDING THE CAPITAL REGION COULD RECEIVE UP TO AN
INCH OF PRECIPITATION.
DID NOT TINKER WITH OVERNIGHT LOWS...THEY LOOK IN THE BALL PARK.
WITH CLOUDS AND A LIGHT BREEZE IN PLACE...TEMPS WILL DROP
TONIGHT...BUT WILL NOT FREE FALL TOO MUCH. MIN TEMPS WILL RANGE FROM
NEAR 20 IN THE ADIRONDACKS TO NEAR 30 IN THE CAPITAL REGION/MID
HUDSON VALLEY.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY/...
FRIDAY...A REDUNDANT FORECAST WILL BE OCCURRING WITH THE STACKED
LOW...AS IT SLOWLY RETROGRADES EASTWARD OVER ERN NY AND NEW
ENGLAND. ANOTHER SPOKE OF VORTICITY ROTATING AROUND THE CUTOFF IN
THE CYCLONIC FLOW MAY FOCUS ISOLD-SCT RAIN AND SNOW SHOWERS AGAIN.
CHC AND LIKELY POPS WERE USED NORTH AND WEST OF THE CAPITAL
REGION. THE BEST CHC FOR SNOW SHOWERS WILL BE AT ELEVATIONS
GREATER THAN 1500 FT. LIGHT ACCUMULATIONS OF A COATING TO A HALF
AN INCH WILL BE POSSIBLE. ISOLD-SCT LIGHT RAIN SHOWERS WILL BE
POSSIBLE ELSEWHERE. THE MID HUDSON VALLEY...AND NW CT WILL LIKELY
REMAIN DRY. MAX TEMPS CLOSER TO A BLEND OF THE GFSMOS AND NAMMOS
GUIDANCE WERE USED WITH HIGHS IN THE U30S TO L40S IN THE
VALLEYS...AND GENERALLY U20S TO M30S OVER THE MTNS.
FRI NIGHT...THE CUTOFF LOW STARTS TO BECOME STRETCHED AND
ELONGATED OVER THE NORTHEAST. THE NAM/GFS HAS ANOTHER LOBE OF
VORTICITY MOVING ACROSS THE REGION TAPPING INTO SOME LOW OR MID
LEVEL MOISTURE. A SLIGHT TO LOW CHC OF SNOW SHOWERS IS LIKELY
AGAIN FROM THE CAPITAL REGION NORTH AND WEST. AGAIN...LIGHT SNOW
ACCUMS ARE POSSIBLE OF A COATING TO LESS THAN AN INCH. LOWS ARE
EXPECTED TO BE IN THE LOWER TO M20S WITH SOME TEENS OVER THE SRN
DACKS.
SAT-SUN...THE CUTOFF UPPER LOW CONTINUES TO PLAGUE NY AND NEW
ENGLAND WITH CLOUDS...AND A LOW RISK OF RAIN AND SNOW SHOWERS. THE
NAM/CANADIAN GUIDANCE INDICATES MORE THAN THE GFS THAT A STRONG
VORT MAX ROTATING AROUND THE CUTOFF UPPER LOW HIGH CHANCES OF
RAIN/SNOW SHOWERS LATE SAT INTO SAT NIGHT/SUNDAY MORNING. THE
COLUMN WILL DEFINITELY BE COLD ENOUGH FOR MORE SNOW THAN RAIN. THE
MOISTURE IS LIMITED UTILIZED BY THE CYCLONIC VORTICITY ADVECTION.
WE USED NO POPS OR SLIGHT CHC POPS IN THE HUDSON RIVER VALLEY ON
SAT...AND HIGH CHC OR LIKELY POPS OVER THE WRN DACKS...NRN
CATSKILLS...SRN GREENS AND BERKS. SAT NIGHT INTO SUNDAY...POPS
WERE INCREASED INTO THE CHC CATEGORY NORTH OF THE MID HUDSON
VALLEY. IT IS POSSIBLE MOST OF THE DAYS COULD BE DRY DUE TO SOME
DRYING INDICATE IN THE COLUMN BASED ON THE SOUNDINGS. TEMPS LOOK
SEASONABLE...AND A SHADE ABOVE NORMAL FOR THE FIRST WEEKEND OF
MARCH.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE PATTERN DURING THE FIST PART OF THE PERIOD WILL FEATURE A
CONTINUATION OF A CYCLONIC FLOW REGIME CIRCULATING AROUND A CUT-OFF
UPPER LEVEL LOW OVER THE CANADIAN MARITIMES. THIS WILL RESULT IN A
NORTHERLY FLOW WITH A CHANCE OF SNOW SHOWERS IN THE MOUNTAINS...WITH
A SLIGHT CHANCE OF RAIN OR SNOW SHOWERS IN THE VALLEYS. PRECIP TYPE
IN VALLEY LOCATIONS WILL BE DIURNALLY DEPENDENT. OVERALL THIS
PATTERN SHOULD REMAIN OVER THE AREA THROUGH TUESDAY WITH
TEMPERATURES NEAR NORMAL.
THEN FOR THE MID WEEK PERIOD...ATTENTION WILL SHIFT TO A POSSIBLE
DEVELOPING STORM SYSTEM EMERGING OUT OF THE ROCKIES AND SOUTHERN
PLAINS...WHICH IS GENERALLY FORECAST TO TRACK ACROSS THE CAROLINAS
LATE TUESDAY INTO WEDNESDAY. AT THIS TIME MOST SOURCES OF MODEL
GUIDANCE DEPICT THIS SYSTEM TRACKING WELL SOUTH OF OUR AREA...BUT
THERE IS A DECENT AMOUNT OF SPREAD AS WELL. SO WHILE THE PROBABILITY
THIS STORM IMPACTS OUR AREA IS LOW...IT IS NOT ZERO AND WE WILL NEED
TO WATCH HOW THIS SYSTEM EVOLVES.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
COMBINATION OF THE INFLUENCE FROM THE UPPER LOW NEARBY AND AN
OCCASIONAL WAVE PROVIDING A PERIOD OF LIGHT RAIN AND/OR SHOWER...WE
WILL KEEP AT LEAST MVFR CIGS IN THE TAFS AT THIS TIME. EXCEPTION
WOULD BE KPSF WHERE IFR CONDITION SHOULD PREVAIL THROUGH THE
REMAINDER OF THE OVERNIGHT PERIOD. PER THE ENHANCED IR
IMAGERY...SEEMS KPOU MIGHT CLEAR OUT TO ALLOW FOR QUICK VIS
REDUCTION TO IFR AND WE WILL PLACE THIS IN THE TAF.
DURING THE DAYLIGHT HOURS...WEST-NORTHWEST WINDS WILL INCREASE TO
LESS THAN 10 KTS WHICH SHOULD ASSIST WITH VISIBILITY IMPROVEMENTS
BUT THE CIGS SHOULD REMAIN INSIDE THE MVFR THRESHOLDS. MAIN
QUESTION WILL BE SHOWER COVERAGE AS WE WILL CONTINUE WITH THE VCSH
AT THIS TIME.
TONIGHT...LOW LEVEL MOISTURE REMAINS HIGH SO WE CAN ONCE AGAIN SEEN
CONDITIONS DROP INTO THE LOW MVFR OR INTO THE IFR CONDITIONS TOWARD
MIDNIGHT.
OUTLOOK...
FRI NT-MON...VFR/MVFR. SLIGHT CHC/CHC -SHSN/-SHRA.
TUE...VFR. NO SIG WX.
&&
.HYDROLOGY...
WIDESPREAD HYDRO PROBLEMS ARE NOT EXPECTED THE NEXT 5 DAYS. FLOWS
CONTINUE TO LOWER IN THE HOUSATONIC BASIN INCLUDING THE STILL
RIVER AT BROOKFIELD...WHERE IT CONTINUES TO FALL FROM THE ALERT
STAGE DUE TO THE RAIN AND SNOW MELT YESTERDAY.
ANY PRECIPITATION OVER THE NEXT FIVE DAYS WILL BE LIGHT WITH A
FEW HUNDREDTHS TO A COUPLE TENTHS OF AN INCH. THE MOUNTAINS WILL
HAVE MOSTLY SNOW. THE VALLEY LOCATIONS COULD HAVE LIGHT RAIN OR
SNOW WITH LITTLE OR NO ACCUMULATIONS.
OVERALL...MAIN STEM RIVERS SHOULD GENERALLY RECEDE INTO EARLY NEXT
WEEK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS/HWJIV
NEAR TERM...FRUGIS/HWJIV
SHORT TERM...WASULA
LONG TERM...JPV
AVIATION...BGM
HYDROLOGY...HWJIV/WASULA
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
918 PM EST SAT MAR 2 2013
.SYNOPSIS...
A PERSISTENT AREA OF LOW PRESSURE SOUTHEAST OF NEWFOUNDLAND WILL
DEVELOP WESTWARD TO NOVA SCOTIA THIS WEEKEND AND THEN TURN
SOUTHEASTWARD OUT TO SEA MONDAY. LOW PRESSURE DEVELOPING OVER THE
OHIO VALLEY TUESDAY SHOULD MOVE TO THE VIRGINIA...NORTH CAROLINA
BORDER WEDNESDAY. THEREAFTER...THERE IS TRACK UNCERTAINTY...BUT
THIS STRONG STORM SHOULD MOVE SLOWLY OUT TO SEA ON THURSDAY.
HIGH PRESSURE WILL FOLLOW FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A PERSISTENT UPPER-LEVEL TROUGH WILL CONTINUE TO CONTROL OUR
WEATHER. HI-RES RAP SHOWS THE MID-LEVEL CLOSED LOW ACROSS
NORTHEAST NEW JERSEY AND PER RADAR REFLECTIVITIES THAT WOULD MAKE
SENSE. WE ARE SEEING SOMEWHAT GREATER DBZ SIGNATURES JUST WEST OF
LONG ISLAND, RIGHT UNDER THE LOBE OF MID-LEVEL VORTICITY. ANY
PRECIPITATION WILL BE RATHER LIGHT, THEREFORE CONTINUED WITH
FLURRIES/SPRINKLES OUTSIDE OF NORTHERN NEW JERSEY AND THE POCONOS.
LOCALIZED ACCUMULATIONS WILL BE ON THE ORDER OF A TENTH OR TWO ACROSS
THESE AREAS AS THE LOW-LEVELS ARE RATHER DRY. WHILE THE OVERALL
MOISTURE IS NOT ALL THAT DEEP, ENOUGH IS PRESENT IN COMBINATION
WITH QUITE COLD AIR ALOFT /-25C TO -30C AT 500 MB/ TO MAINTAIN
LOTS OF CLOUDS.
THE WINDS WHILE THEY MAY TEND TO BE LIGHTER THROUGH THE EVENING,
THEY MAY START TO INCREASE SOME TOWARD DAYBREAK AS THE PRESSURE
GRADIENT TIGHTENS SOME. AS FOR LOW TEMPERATURES, WE MAINLY USED AN
EVEN NAM/GFS BLEND WITH SOME MINOR ADJUSTMENTS THEREAFTER. WE
INCORPORATED SOME OF THE LAMP/LAV GUIDANCE INTO THE HOURLY
TEMPERATURE GRIDS THROUGH THE EVENING TO HELP CAPTURE SOME OF THE
TRENDS THAT OCCURRED THUS FAR THIS AFTERNOON.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
THE WEST OR SOUTHWEST PORTION OF A CLOSED LOW WITHIN A LARGER
UPPER-LEVEL TROUGH SHOULD SWING ACROSS OUR AREA. THIS IS ASSOCIATED
WITH A RATHER STRONG MID LEVEL SHORT WAVE/VORTICITY MAXIMUM. AS THIS
FEATURE STARTS TO SHIFT TO OUR EAST DURING THE AFTERNOON, THE
VORTICITY IS FORECAST TO BECOME MORE CHANNELIZED AS SOME WEAK
RIDGING TRIES TO APPROACH THE OHIO VALLEY. ANOTHER STRONGER SHORT
WAVE THOUGH MAY DIVE SOUTHEASTWARD INTO THE UPPER OHIO VALLEY DURING
THE AFTERNOON, WHICH WILL TEND TO HOLD THE ENTIRE UPPER-LEVEL
TROUGH IN THE EAST.
AS THIS UPPER-LEVEL TROUGH OR CLOSED LOW SHIFTS EASTWARD DURING THE
AFTERNOON, THE CORE OF THE MID LEVEL COLD POCKET /NEAR -30C/ WILL
ALSO SHIFT OFFSHORE. THE FORECAST SOUNDINGS OVERALL SHOW THE REGION
HITTING THE CONVECTIVE TEMPERATURES ONCE AGAIN. AS A RESULT, WE WILL
PROBABLY HAVE A REPEAT OF SATURDAY`S SKY COVER WITH ANY BREAKS
FILLING IN THROUGH THE MORNING. THE GFS IS NOT AS ROBUST WITH THIS
IDEA /HIGHER CONVECTIVE TEMPERATURES/ COMPARED TO THE NAM AND SOME
OTHER GUIDANCE, HOWEVER GIVEN THE FORECAST THERMAL PROFILES AND
MOISTURE IN THE LOWER LEVELS, WE WILL CONTINUE WITH A GOOD AMOUNT OF
CLOUDS FOR MUCH OF THE DAY. AS THE UPPER-LEVEL SYSTEM SHIFTS
EASTWARD, THE PRESSURE GRADIENT IS FORECAST TO TIGHTEN UP SOME.
GIVEN THE MUCH COLDER AIR ALOFT COMBINED WITH SOME WARMING WITHIN
THE BOUNDARY LAYER SHOULD RESULT IN DEEPENING VERTICAL MIXING.
THIS SHOULD RESULT IN BRISK CONDITIONS DEVELOPING THROUGH THE MORNING
AND INTO THE AFTERNOON.
WHILE WE COULD HAVE SOME FLURRIES AROUND, THE MAIN SHORT WAVE
GRADUALLY SHIFTING TO OUR EAST WITH A LESSENING OF THE PVA SHOULD
LIMIT THIS. THEREFORE ATTM, WE CONFINED THE FLURRIES TO THE HIGHER
ELEVATIONS OF THE FAR NORTHWEST ZONES.
AS FOR TEMPERATURES, WE GENERALLY TOOK A MOS BLEND WHICH IS A BIT
COLDER THAN CONTINUITY. THIS IS A RESULT OF THE RATHER COLD AIR
ALOFT REMAINING IN PLACE AND THE IDEA THAT THE CLOUD COVER WILL HELP
TO SLOW THE WARMING OF THE BOUNDARY LAYER SOME.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
**POTENT STORM SHOULD CONTINUE TO BE MONITORED FOR OUR AREA
WEDNESDAY INTO THURSDAY**
NORTHWEST SURFACE FLOW DOMINATES MOST OF THIS PERIOD WITH CONTINUING
POTENTIAL FOR A 24 HOUR STRONG COASTAL STORM DURING THE MIDDLE OF
NEXT WEEK.
500 MB: RELATIVE TO NORMAL...BLOCKING CONTINUES IN NORTHEAST CANADA
WHILE ONE SUBSTANTIAL TROUGH IN THE SE USA EXITS OUT TO SEA TO START
THE PERIOD. A STRENGTHENING SHORT WAVE MOVING SOUTHEASTWARD FROM THE
NORTHERN ROCKIES SUNDAY NIGHT ARRIVES IN NORTH CAROLINA...VIRGINIA
BY WEDNESDAY EVENING AS A LARGE -1 TO -2 SD DEEP CYCLONIC CIRCULATION
SYSTEM. THEN IT HEADS EAST OR NORTHEAST FROM THERE WHILE RIDGING
BUILDS ALONG THE EAST COAST FRIDAY...IN THE WAKE OF WHATEVER OCCURS
DURING MIDWEEK. 00Z/2 GEFS RMOP /RELATIVE MEASURE OF PREDICTABILITY/
PLACES CONSIDERABLE CONFIDENT PREDICTABILITY ON THE POSITION OF
THE UPPER AIR PATTERN WEDNESDAY EVENING FROM DELMARVA SOUTHWARD
AND ALSO ACROSS NORTHEAST CANADA...BUT...HAS MUCH MORE SPREAD IN
THE DETAILS OF THE PATTERN FROM NEW JERSEY AND PENNSYLVANIA
NORTHWARD. THAT SPREAD INFUSES THE FORECAST WITH LOWER THAN
AVERAGE CONFIDENCE FOR A DAY4-5 FORECAST IN OUR AREA INCLUDING
WIND/TEMPERATURE AND PRECIPITATION. IT IS WORTHY OF MONITORING FOR
POTENTIAL IMPACT BUT BEING AWARE THAT THE BULK OF THIS
STORM...WHATEVER MAGNITUDE COULD MISS US JUST TO OUR SOUTH.
CALENDAR DAY AVERAGE TEMPERATURES: A BIT BELOW NORMAL MONDAY...NEAR
NORMAL TUESDAY...AND THEN JUST A BIT ABOVE NORMAL WEDNESDAY THROUGH
SATURDAY WITH CHANCE OF 5 DEGREES ABOVE NORMAL NEXT FRIDAY AND
SATURDAY.
THE DAILIES...
STATISTICAL GRIDDED BASIS: 12Z/2 BLENDED NCEP MOS GUIDANCE THROUGH
12Z TUE EXCEPT AS NOTED. THEREAFTER...FOR TUE AND TUE NIGHT MAINLY
12Z/2 GFS MEX MELDED WITH THE 12Z NAM AND 09Z SREF FOR THE FIRST
12 HOURS OF THIS 24 HOUR PERIOD. THEN FOR WED AND BEYOND... 15Z/2
HPC GUIDANCE...AT TIMES MODIFIED BY THE 12Z/2 GFS OPERATIONAL MEX
GUIDANCE.
SUNDAY NIGHT THROUGH MONDAY... VARIABLE CLOUDINESS...WITH THE MORE
PERSISTENT CLOUD COVER OVER THE HIGHER TERRAIN OF THE NORTHWEST
WHERE THERE MIGHT BE A FEW FLURRIES. NORTHWEST WIND GUST 15 TO 30
MPH.
MONDAY NIGHT THROUGH TUESDAY...PARTLY CLOUDY...AND AGAIN THE CLOUDINESS
PREDOMINANT OVER THE NORTHWEST HIGHER TERRAIN. NORTHWEST WIND STILL
GUSTY 15-25 MPH MONDAY EVENING THEN DIMINISHING AND BECOMING LIGHT
ON TUESDAY. ON TUESDAY..THE 12Z GFS MEX MOS TEMPS LOOK A LITTLE
WARM WHEN COMPARED TO THE 00Z/2 ECMWF AND 08Z/2 PHI MAX TEMP FCST
AS WELL AS COMPARED TO THE COLDER 12Z/2 NAM 2M TEMPS. RAN A 50 50
COMPROMISE WITH THE 08Z/2 KPHI FCST AND COOLED THIS MOS GUIDANCE
BY SEVERAL DEGREES.
WEDNESDAY...A POSSIBLE STRONG NOREASTER WITH ATTENDANT PRECIPITATION
TYPE/AMOUNT HIGHLY UNCERTAIN...IF ANY...WHICH ULTIMATELY INFLUENCES
THE MAX/MIN TEMPERATURES AND OF COURSE WIND SPEED UNCERTAIN. NO
MATTER ITS A CLOUDY PERIOD WITH PRECIPITATION LIKELY OVER DE/E MD
AND S NJ. NORTHEAST WIND WITH A WIDE RANGE OF GUST SPEEDS...AND
STRONGER ON THE COAST. WE`LL START WITH 20 TO 30 MPH INLAND AND
POSSIBLE 40 + ALONG THE COAST...ESPECIALLY DELAWARE. 12Z/2GGEM IS
MUCH MORE ABUNDANT THAN THE GFS. AM AWARE THE 12Z GFS MOS GUIDANCE
IS MUCH WARMER THAN HPC BUT FOR NOW...IF WE`RE THINKING A CLOUDY
DAY WITH POSSIBLE PCPN...WE REMAIN WITH THE COLDER HPC GUIDANCE-
ALSO SUPPORTED BY THE FAIRLY COLD GFS BL TEMP. WE ARE ALSO AWARE
OF THE STRONG WIND OF THE 12Z ECMWF.
THURSDAY...THE DEPARTING STRONG COASTAL STORM IS ON THE WANE AND
CONDITIONS ARE IMPROVING...ESPECIALLY LATE IN THE DAY. NORTH WIND
GUSTY 20 TO 30 MPH....STRONGER ALONG THE COAST. 12Z/2 GGEM IS
STORMY. FOR NOW THE 12Z GGEM WAS NOT A BIG PART OF THIS FCST...EXCEPT
AS ANOTHER MEMBER OF POSSIBLE SCENARIOS. 12Z/2 GFS MOS IS MUCH
WARMER THAN THE HPC GUIDANCE...FOR NOW REMAINED WITH THE COOLER
HPC GUIDANCE UNTIL WE KNOW CLEARING OCCURS AND ANY PCPN HAS MOVED
OUT TO SEA.
FRIDAY AND SATURDAY...LOOKS TO BE THE NICEST WEATHER OF THIS FORECAST
PERIOD...MOSTLY CLEAR SKIES AND WARMING DAYTIME TEMPERATURES.
GUSTS PROBABLY UNDER 20 MPH. LOWERED THE 14Z/2 HPC GUIDANCE DEWPOINTS
MUCH CLOSER TO THE DRIER 12/2 MEXMOS...PER EXPECTED CONTINENTAL
NNW SFC FLOW.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...OVERALL, VFR CEILINGS. THERE SHOULD BE SOME FLURRIES
AROUND, MAINLY THIS EVENING. NORTHWEST WINDS NEAR 10 KNOTS.
SUNDAY...VFR CEILINGS. NORTHWEST WINDS 10-15 KNOTS WITH GUSTS TO
20-25 KNOTS.
OUTLOOK...
SUN NIGHT AND MON...VFR OCNL CIGS AOA 4000 FT EXCEPT MVFR CIGS
POSSIBLE IN THE POCONOS WHERE A FEW FLURRIES MAY OCCUR. NORTHWEST
WIND OCNLY GUST 20-30 KNOTS. HIGH CONFIDENCE.
MONDAY NIGHT...MAINLY VFR WITH A LIKELIHOOD FOR CLEARING OF THE
CLOUDS AOA 4000 FT. NW WIND GUST 15-250 KTS IN THE EVENING DIMINISHING
LATE. HIGH CONFIDENCE.
TUE...MAINLY VFR. SCT-BKN GENERALLY AOA 4000 FT. LIGHT MAINLY NORTH
WIND. HIGH CONFIDENCE.
WED...SUB-VFR POSSIBLE...EXCEPT PROBABLE DE/E MD. LOW PRESSURE
WILL MOVE FROM THE OHIO VLY TO THE THE VCNTY KORF WEDNESDAY
EVENING. AFTER THAT A LOT OF UNCERTAINTY STILL EXISTS AS TO ITS
TRACK, STRENGTH AND IMPACTS ON OUR AREA. LESS THAN AVERAGE
CONFIDENCE. NE WIND SHOULD GENERALLY GUST 20-30 KTS DURING THE DAY
AND EVENING WITH HIGHER GUSTS ALONG THE COAST.
THU...ANY SUB VFR CONDITIONS EARLY...IMPROVES TO VFR BY DAYS END.
N WIND G 20-30 KTS DURING THE DAY. CONFIDENCE AVERAGE.
&&
.MARINE...
AN UPPER-LEVEL TROUGH WILL BE MAINTAINED ACROSS THE EAST THROUGH
SUNDAY. THIS WILL CONTINUE A NORTHWESTERLY FLOW ACROSS THE WATERS.
THE AIR ALOFT IS QUITE COLD HOWEVER IT APPEARS THAT THE BOUNDARY
LAYER IS JUST MILD ENOUGH TO REDUCE THE VERTICAL MIXING. IN
ADDITION, THE WINDS NOT TO FAR ABOVE THE SURFACE ARE NOT ALL THAT
STRONG, THEREFORE GUSTS SHOULD ONLY TOP OUT AT 20 KNOTS. AS A
COMPACT CLOSED LOW REMAINS NEARBY, THE PRESSURE GRADIENT IS FORECAST
TO START TIGHTENING UP SOME TOWARD DAYBREAK. THIS MAY ALLOW SOME
UPTICK IN THE WINDS, WHICH SHOULD CONTINUE DURING SUNDAY. THE
FORECAST SOUNDINGS SUGGEST THAT THE VERTICAL MIXING IS THERE HOWEVER
THE FLOW WITHIN IT IS MARGINAL FOR ADVISORY LEVEL GUSTS /SOMEWHAT
BETTER SOUTH THAN NORTH/. SINCE IT LOOKS MARGINAL, WE WILL HOLD OFF
ON ISSUING A SMALL CRAFT ADVISORY. SEAS ARE FORECAST TO BE 3 FEET OR
LESS.
OUTLOOK...
AN SCA HEADLINE WILL BE NEEDED FOR MONDAY AND MONDAY EVENING AND
PROBABLY STARTING SOONER.. SUNDAY NIGHT.
SCA OCCASIONAL NW WIND GUSTS 25-30 KT SUN NIGHT THROUGH MONDAY
EVENING...ESPECIALLY ATLANTIC COASTAL WATERS WHERE ISOLATED GUST
35 KT POSSIBLE MONDAY EVENING. FOR NOW CAPPED THE GRIDDED GUSTS AT
32 KNOTS.
TUESDAY...NO HEADLINE ANTICIPATED.
WEDNESDAY/THURSDAY...A STRONG GALE ANTICIPATED FOR A PORTION OF THE
WATERS...ESPECIALLY S NJ AND DE WATERS WITH POSSIBLE STORM FORCE
GUSTS AROUND 50 KNOTS OFF DELAWARE..DEPENDENT IN LARGE PART ON THE
TRACK. SEAS 10 TO 15 FEET APPEAR PROBABLE WEDNESDAY NIGHT AND
THURSDAY... ESPECIALLY IN THE ATLANTIC WATERS OFF DELAWARE.
DIMINISHING WIND AND VERY SLOWLY SUBSIDING NE SWELL IN THE
ATLANTIC WATERS THURSDAY AFTERNOON.
&&
.TIDES/COASTAL FLOODING...
GFS ESTOFS /EXTRATROPICAL SURGE AND TIDE OPERATIONAL FORECAST SYSTEM/
SINCE AT LEAST YESTERDAYS 12Z/1 CYCLE HAS BEEN ADVERTISING A 2-3
FT SURGE FOR THE THURSDAY MORNING MARCH 7 HIGH TIDE...ESPECIALLY
ATLANTIC CITY SOUTHWARD. SEAS SHOULD BE 10 FEET OR HIGHER AT THAT
TIME.
THIS PATTERN DEVELOPS A COASTAL FLOOD RISK. FOR STARTERS AN ADVISORY
SITUATION /MINOR CF/ IS FORESEEN FROM ATLANTIC CITY SOUTHWARD WITH
SOME POTENTIAL FOR A SIGNIFICANT COASTAL FLOOD WARNING EVENT FOR
THE THURSDAY MORNING ATLANTIC WATERS HIGH TIDE CYCLE.
THIS TIDE IS NOT ASTRONOMICALLY UNUSUALLY HIGH.
YET A SURGE OF 2.5 FEET WOULD REACH THE THRESHOLD OF MDT COASTAL
FLOODING.
THE BASIS FOR THE SURGE IS PRIMARILY THE PERSISTENT 24 HOUR
ONSHORE FLOW WITH A PROBABLE NE GALE LATER WED INTO EARLY
THURSDAY.
SUBSEQUENT TRACK AND INTENSITY WILL BETTER INFORM WHETHER THIS IS
JUST A MINOR EVENT WITH THE BRUNT PASSING SOUTH OF OUR AREA...OR A
MORE IMPORTANT COASTAL FLOOD THREAT.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DRAG
NEAR TERM...GORSE/HEAVENER
SHORT TERM...GORSE
LONG TERM...DRAG
AVIATION...DRAG/GORSE/HEAVENER
MARINE...DRAG/GORSE
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
905 PM CST SAT MAR 2 2013
.DISCUSSION...
821 PM CST
MADE SOME MINOR ADJUSTMENTS TO FORECAST/GRIDS. WEAK LAKE EFFECT
SNOW BAND HAS DRIFTED WEST TO THE ILLINOIS SHORE SO HAVE ADDED
SOME SMALL POPS FOR LIGHT SNOW SHOWERS. LATEST SHORT TERM
GUIDANCE FROM HRRR AND RAP WOULD SUGGEST WEAK CONVERGENCE ZONE
WILL REMAIN DOWN CENTER-WEST SIDE OF LAKE OVERNIGHT. MAIN BAND
WILL BE COMING INTO NORTHWEST INDIANA BUT AS THE BAND
MEANDERS...SOME LIGHT SNOW COULD FALL ALONG THE ILLINOIS SHORE AT
TIMES. BUFKIT INDICATES MARGINAL TEMPERATURES BUT SHALLOW CLOUD
DEPTH...SO AM NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION...
PERHAPS A FEW TENTHS OF AN INCH IN NORTHWEST IN.
THE OTHER CONCERN IS TEMPERATURES. WITH CLEAR SKIES AWAY FROM THE
LAKE...LIGHT WINDS AND FRESH SNOWPACK...TEMPS COULD GET INTO THE
SINGLE DIGITS ACROSS THE NORTH SUBURBS WHERE SNOW COVER IS
DEEPEST. ALREADY SEEING SINGLE DIGITS AND LOW TEENS IN SRN WI AT
THIS HOUR.
ALLSOPP
//PREV DISCUSSION...
332 PM CST
MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LINGERING LAKE EFFECT
SNOW SHOWERS ACROSS NORTHWEST INDIANA TONIGHT INTO EARLY SUNDAY
MORNING...BUT OF MORE IMPORTANCE ARE THE INCREASED PROBABILITIES
FOR A SIGNIFICANT SNOW ACCUMULATION FOR A GOOD PORTION OF THE CWA
MONDAY NIGHT INTO TUESDAY NIGHT.
LATEST RADAR IMAGERY DEPICTING PERSISTENT LAKE EFFECT SNOW SHOWERS
FOR AREAS ACROSS NORTHEAST ILLINOIS AND NORTHWEST
INDIANA...PRIMARILY EAST OF INTERSTATE 57 LATE THIS AFTERNOON. A
MORE BROAD AREA OF LIGHT SNOW HAD DEVELOPED WITH A BETTER BAND
NOTED PUSHING SOUTH INTO LAKE/PORTER COUNTIES EARLIER TODAY.
VISIBILITY AND ISOLATED SLIPPERY CONDITIONS HAVE BEEN A CONCERN
BUT A SAVING GRACE HAS BEEN THE RELATIVELY WARMER CONDITIONS AT
AROUND FREEZING. THIS HAS ALLOWED FOR MOST OF THE MAJOR HIGHWAYS
TO REMAIN ONLY WET...PER TRAFFIC CAMS ACROSS NORTHWEST INDIANA.
ALTHOUGH IN THE NEAR TERM...HAVE NOTICED A DIMINISHING TREND WITH
THE OVERALL DEVELOPMENT AS WELL AS THE STRONGER MORE DEFINED BAND
IN INDIANA. THIS IS IN RESPONSE TO THE LOSS OF THE CONVERGENCE
ALONG THE SOUTHERN END OF THE LAKE AS WELL AS SOME MODERATING
THERMODYNAMIC CONDITIONS ACROSS THE ENTIRE LAKE. DONT FEEL AS IF
OUR CWA IS COMPLETELY THROUGH WITH OBSERVING SOME LAKE EFFECT SNOW
TONIGHT INTO SUNDAY MORNING DESPITE BOUNDARY LAYER FLOW SHIFTING
MORE NORTH/NORTHWEST THIS EVENING. COLDER AIR CURRENTLY WORKING
ITS WAY SOUTH DOWN THE LAKE WILL CONTINUE TONIGHT REINFORCING
DELTA TS OVER THE LENGTH OF THE LAKE. THIS COINCIDING WITH A LONG
FETCH AS WELL AS SHORT RANGE GUIDANCE INDICATING THAT BETTER LOW
LEVEL FORCING/CONVERGENCE WILL RETURN BACK TO THE CWA AFTER THE
9PM TIME FRAME TONIGHT...DO EXPECT REDEVELOPMENT OF SNOW SHOWERS
BUT PRIMARILY FOR LAKE AND PORTER COUNTIES IN INDIANA. SO HAVE
INCREASED POPS TONIGHT ACROSS THESE AREAS AND HAVE INCLUDED
ADDITIONAL SNOW ACCUMULATION OF A COUPLE OF INCHES...WHICH SEEMS
PROBABLE WITH COLDER TEMPS EXPECTED TONIGHT. THE REMAINDER OF THE
CWA WILL OBSERVE QUIET AND MOSTLY CLEAR SKIES TONIGHT...OUTSIDE OF
A FEW PASSING HIGH LEVEL CLOUDS. ALSO DO EXPECT A CHILLY NIGHT
WITH LOW TEMPS IN THE TEENS EXPECTED ACROSS MOST OF THE
CWA...OUTSIDE OF LAKE EFFECT CLOUD COVER IN NORTHWEST INDIANA.
FAIRLY SIMILAR CONDITIONS ARE EXPECTED ACROSS THE LAKE SUNDAY
MORNING...WITH LAKE EFFECT SNOW STILL AFFECTING PRIMARILY PORTER
COUNTY. DONT EXPECT MUCH IN TERMS OF ACCUMULATION AS BETTER
DEVELOPMENT SHOULD BE JUST EAST OF PORTER COUNTY...WITH BOUNDARY
LAYER FLOW CONTINUING TO SHIFT AND CONDITIONS OVER THE LAKE
BECOMING LESS FAVORABLE. SKIES WILL BE CLEARING FOR ALL OF THE CWA
ON SUNDAY AS VORT MAX SLIDES SOUTHEAST OF THE AREA AND RISING
HEIGHTS ALOFT USHER IN A SURFACE RIDGE. WITH A WARM MARCH SUN AND
A MODERATING TEMP PROFILE...RELATIVELY PLEASANT CONDITIONS IN THE
LOW TO MID 30S WILL BE OBSERVED. ALTHOUGH...DO EXPECT THIS TO BE
RATHER BRIEF AS FOCUS THEN SHIFTS TOWARDS THE APPROACHING SYSTEM
FOR THE START OF THE WEEK.
AS WAS MENTIONED ABOVE...AM GETTING A LITTLE MORE CONCERNED AT THE
POSSIBILITY FOR A SIGNIFICANT SNOWFALL ACROSS A PORTION OF THE CWA
MONDAY NIGHT INTO TUESDAY NIGHT. THE SYSTEM WHICH WE HAVE
CONTINUED TO MONITOR OVER THE LAST SEVERAL DAYS HAS STARTED TO
BECOME MORE CONSISTENT AMONG VARIOUS MODEL GUIDANCE. DESPITE THE
FACT THAT THERE ARE STILL SOME TIMING AND EXACT PLACEMENT
ISSUES...CONSENSUS IS GROWING FOR A STRONG SYSTEM TO AFFECT
NORTHERN ILLINOIS AND NORTHWEST INDIANA. A STRONG UPPER LEVEL
SYSTEM IS STILL FORECAST TO SLIDE ACROSS THE NORTHERN PLAINS BY
MONDAY...THEN QUICKLY DIG SOUTHEAST TOWARDS THE MID MISSISSIPPI
VALLEY MONDAY NIGHT INTO TUESDAY. WAA OUT AHEAD OF THIS SYSTEM
WILL SLOWLY BRING PRECIP ACROSS PRIMARILY THE SOUTHWEST PORTIONS
OF THE CWA DURING THE DAY ON MONDAY. WITH SLIGHT WARMING...A MIX
OF LIGHT RAIN OR SNOW WILL BE POSSIBLE FOR AREAS ACROSS THE
SOUTHERN CWA...BUT WITH LIGHT SNOW EXPECTED FURTHER NORTHWEST.
ALTHOUGH...REALLY NOT ANTICIPATING MUCH IN TERMS OF ANY
ACCUMULATION THROUGH MOST OF MONDAY WITH RELATIVELY WARMER TEMPS
IN PLACE. ITS NOT UNTIL LATE MONDAY NIGHT INTO TUESDAY THAT MORE
WIDESPREAD DEVELOPMENT WILL SHIFT EAST ACROSS THE CWA. DO EXPECT
ALL SNOW FOR THIS INITIAL TIME FRAME WITH LARGE SCALE LIFT RAPIDLY
COOLING THE TEMP PROFILE ACROSS THE AREA. LARGE SCALE FORCING
INCREASES...AND REALLY GETS GOING ON TUESDAY AS THIS UPPER LEVEL
LOW SHIFTS SOUTHEAST AND THE CWA LIKELY OBSERVES PERIODS OF
PERSISTENT WAA...WITH LIKELY AREAS OF DEFORMATION TO PIVOT ACROSS
THE CWA. ABUNDANT MOISTURE WILL BE PRESENT AND IS SEEN WITH THE
QPF THAT MODEL GUIDANCE IS DEVELOPING...WHICH SEEMS LIKE A VALID
SOLUTION GIVEN THE STRENGTH OF THIS DYNAMIC SYSTEM. WIDESPREAD
SNOW ACCUMULATION IS APPEARING MORE PROBABLE ACROSS THE ENTIRE CWA
TUESDAY INTO TUESDAY NIGHT AND AT THIS TIME...MORE SIGNIFICANT
SNOWFALL POSSIBLY IN EXCESS OF 6 INCHES IS PROBABLE FOR AREAS
SOUTH OF INTERSTATE 80. THIS SYSTEM WILL DEFINITELY NEED TO BE
MONITORED WITH SUCCESSIVE FORECASTS AS GUIDANCE COULD CONTINUE TO
VARY. NONETHELESS...IT IS APPEARING THAT THE REGION AND A PORTION
OF OUR AREA IN NORTHEAST ILLINOIS AND NORTHWEST INDIANA COULD
OBSERVE A SIGNIFICANT SNOW ACCUMULATION WITH WIDESPREAD IMPACTS
LATE MONDAY NIGHT INTO TUESDAY NIGHT. GIVEN THE TIME RANGE OF THE
EVENT AND POSSIBLE RANGE OF SOLUTIONS...HAVE HELD OFF ON ANY
HEADLINES BUT WILL CONTINUE TO MONITOR THIS POTENTIAL.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* NONE.
MDB
//DISCUSSION...UPDATED 03Z...
LAKE EFFECT CLOUDS NOW PUSHING JUST EAST OF ORD/MDW BUT CONTINUE
AT GYY. WILL CONTINUE WITH HIGH END MVFR CIGS AT GYY INTO THE
EARLY OVERNIGHT HOURS WHICH MAY NEED FURTHER TWEAKING. WEAK RADAR
RETURNS HAD EXPANDED WESTWARD BUT WEB CAMS AND SURFACE OBS DO NOT
INDICATE MORE THAN FLURRIES. WILL KEEP GYY DRY THOUGH FLURRIES OR
BRIEF LIGHT SNOW ARE POSSIBLE AS LONG AS THE CLOUDS HANG ON.
MDB
FROM 00Z...
HIGH PRESSURE STRETCHED ACROSS THE MISSISSIPPI RIVER VALLEY WILL
DRIFT EASTWARD THROUGH THE TAF PERIOD BRINGING DIMINISHING WINDS
AND VFR CONDITIONS. LAKE EFFECT SNOW SHOWERS ARE CONTINUING ACROSS
NW INDIANA EAST OF GYY AND WILL LIKELY CONTINUE THROUGH MUCH OF
THE NIGHT. THERE IS SOME POTENTIAL THAT GYY DOES GET SKIRTED BY
SOME SNOW SHOWERS LATER THIS EVENING OR OVERNIGHT AS LAKE EFFECT
TRIES TO BECOME SOMEWHAT BETTER ORGANIZED BUT CONFIDENCE IS TOO
LOW TO INCLUDE ANY MENTION IN THE TAF AT THIS TIME. MAY ULTIMATELY
NEED TO RE-INTRODUCE BKN SKY COVERAGE WHICH COULD BE HIGH END
MVFR BUT AT THIS POINT AM THINKING THE CIGS/SNOW SHOWERS WILL
REMAIN JUST TO THE EAST. OTHERWISE...WINDS WILL DIMINISH THROUGH
THE EVENING WITH SOME SCATTERED LAKE CLOUDS SKIRTING THE ILLINOIS
SHORELINE. WINDS WILL REMAIN NORTHERLY IN THE 6 TO PERHAPS 10 KT
RANGE SUNDAY THEN SHIFT NORTHEASTERLY LATE IN THE DAY AS THE HIGH
CRESTS THE AREA. SOME SPOTTY MID AND HIGH CLOUD COVER IS ALL THAT
IS EXPECTED SUNDAY.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* NONE.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...INCREASING SNOW AND MVFR CHANCES MONDAY NIGHT.
TUESDAY...SNOW AND IFR LIKELY.
WEDNESDAY...LINGERING LIGHT SNOW/MVFR BECOMING VFR.
THURSDAY AND FRIDAY...VFR.
MDB
&&
.MARINE...
400 PM CST
NORTH WINDS WILL CONTINUE TO GRADUALLY DIMINISH TO A MODERATE
BREEZE TONIGHT AND SUNDAY AS A RIDGE OF HIGH PRESSURE EXTENDING
FROM HUDSON BAY TO THE SOUTHERN PLAINS MOVES SLOWLY EASTWARD...
REACHING LAKE SUPERIOR...EASTERN WISCONSIN AND ILLINOIS...AND
THE LOWER OHIO VALLEY BY SUNDAY NIGHT. LIGHT BREEZES WILL
INCREASE TO MODERATE NORTHEAST AND EAST BREEZES DURING MONDAY
AND MONDAY NIGHT AS LOW PRESSURE MOVES EAST ACROSS THE CENTRAL
PLAINS TO THE LOWER OHIO VALLEY. AS THE LOW CONTINUES MOVING
OFF TO THE EAST MONDAY NIGHT THROUGH WEDNESDAY WINDS ON LAKE MI
WILL BACK TO OUT OF THE NORTHEAST AND NORTH WHILE FRESHENING TO
STRONG BREEZES. DURING WEDNESDAY AND WEDNESDAY ANOTHER RIDGE OF
HIGH PRESSURE WILL BE MOVING EAST TO ONTARIO... THE UPPER GREAT
LAKES...AND THE MID AND LOWER MS VALLEY ALLOWING WINDS TO
GRADUALLY SLACKEN TO A LIGHT BREEZE AGAIN.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 10 PM SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM
SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
830 PM CST SAT MAR 2 2013
.DISCUSSION...
821 PM CST
MADE SOME MINOR ADJUSTMENTS TO FORECAST/GRIDS. WEAK LAKE EFFECT
SNOW BAND HAS DRIFTED WEST TO THE ILLINOIS SHORE SO HAVE ADDED
SOME SMALL POPS FOR LIGHT SNOW SHOWERS. LATEST SHORT TERM
GUIDANCE FROM HRRR AND RAP WOULD SUGGEST WEAK CONVERGENCE ZONE
WILL REMAIN DOWN CENTER-WEST SIDE OF LAKE OVERNIGHT. MAIN BAND
WILL BE COMING INTO NORTHWEST INDIANA BUT AS THE BAND
MEANDERS...SOME LIGHT SNOW COULD FALL ALONG THE ILLINOIS SHORE AT
TIMES. BUFKIT INDICATES MARGINAL TEMPERATURES BUT SHALLOW CLOUD
DEPTH...SO AM NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION...
PERHAPS A FEW TENTHS OF AN INCH IN NORTHWEST IN.
THE OTHER CONCERN IS TEMPERATURES. WITH CLEAR SKIES AWAY FROM THE
LAKE...LIGHT WINDS AND FRESH SNOWPACK...TEMPS COULD GET INTO THE
SINGLE DIGITS ACROSS THE NORTH SUBURBS WHERE SNOW COVER IS
DEEPEST. ALREADY SEEING SINGLE DIGITS AND LOW TEENS IN SRN WI AT
THIS HOUR.
ALLSOPP
&&
.PREV DISCUSSION...
332 PM CST
MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LINGERING LAKE EFFECT
SNOW SHOWERS ACROSS NORTHWEST INDIANA TONIGHT INTO EARLY SUNDAY
MORNING...BUT OF MORE IMPORTANCE ARE THE INCREASED PROBABILITIES
FOR A SIGNIFICANT SNOW ACCUMULATION FOR A GOOD PORTION OF THE CWA
MONDAY NIGHT INTO TUESDAY NIGHT.
LATEST RADAR IMAGERY DEPICTING PERSISTENT LAKE EFFECT SNOW SHOWERS
FOR AREAS ACROSS NORTHEAST ILLINOIS AND NORTHWEST
INDIANA...PRIMARILY EAST OF INTERSTATE 57 LATE THIS AFTERNOON. A
MORE BROAD AREA OF LIGHT SNOW HAD DEVELOPED WITH A BETTER BAND
NOTED PUSHING SOUTH INTO LAKE/PORTER COUNTIES EARLIER TODAY.
VISIBILITY AND ISOLATED SLIPPERY CONDITIONS HAVE BEEN A CONCERN
BUT A SAVING GRACE HAS BEEN THE RELATIVELY WARMER CONDITIONS AT
AROUND FREEZING. THIS HAS ALLOWED FOR MOST OF THE MAJOR HIGHWAYS
TO REMAIN ONLY WET...PER TRAFFIC CAMS ACROSS NORTHWEST INDIANA.
ALTHOUGH IN THE NEAR TERM...HAVE NOTICED A DIMINISHING TREND WITH
THE OVERALL DEVELOPMENT AS WELL AS THE STRONGER MORE DEFINED BAND
IN INDIANA. THIS IS IN RESPONSE TO THE LOSS OF THE CONVERGENCE
ALONG THE SOUTHERN END OF THE LAKE AS WELL AS SOME MODERATING
THERMODYNAMIC CONDITIONS ACROSS THE ENTIRE LAKE. DONT FEEL AS IF
OUR CWA IS COMPLETELY THROUGH WITH OBSERVING SOME LAKE EFFECT SNOW
TONIGHT INTO SUNDAY MORNING DESPITE BOUNDARY LAYER FLOW SHIFTING
MORE NORTH/NORTHWEST THIS EVENING. COLDER AIR CURRENTLY WORKING
ITS WAY SOUTH DOWN THE LAKE WILL CONTINUE TONIGHT REINFORCING
DELTA TS OVER THE LENGTH OF THE LAKE. THIS COINCIDING WITH A LONG
FETCH AS WELL AS SHORT RANGE GUIDANCE INDICATING THAT BETTER LOW
LEVEL FORCING/CONVERGENCE WILL RETURN BACK TO THE CWA AFTER THE
9PM TIME FRAME TONIGHT...DO EXPECT REDEVELOPMENT OF SNOW SHOWERS
BUT PRIMARILY FOR LAKE AND PORTER COUNTIES IN INDIANA. SO HAVE
INCREASED POPS TONIGHT ACROSS THESE AREAS AND HAVE INCLUDED
ADDITIONAL SNOW ACCUMULATION OF A COUPLE OF INCHES...WHICH SEEMS
PROBABLE WITH COLDER TEMPS EXPECTED TONIGHT. THE REMAINDER OF THE
CWA WILL OBSERVE QUIET AND MOSTLY CLEAR SKIES TONIGHT...OUTSIDE OF
A FEW PASSING HIGH LEVEL CLOUDS. ALSO DO EXPECT A CHILLY NIGHT
WITH LOW TEMPS IN THE TEENS EXPECTED ACROSS MOST OF THE
CWA...OUTSIDE OF LAKE EFFECT CLOUD COVER IN NORTHWEST INDIANA.
FAIRLY SIMILAR CONDITIONS ARE EXPECTED ACROSS THE LAKE SUNDAY
MORNING...WITH LAKE EFFECT SNOW STILL AFFECTING PRIMARILY PORTER
COUNTY. DONT EXPECT MUCH IN TERMS OF ACCUMULATION AS BETTER
DEVELOPMENT SHOULD BE JUST EAST OF PORTER COUNTY...WITH BOUNDARY
LAYER FLOW CONTINUING TO SHIFT AND CONDITIONS OVER THE LAKE
BECOMING LESS FAVORABLE. SKIES WILL BE CLEARING FOR ALL OF THE CWA
ON SUNDAY AS VORT MAX SLIDES SOUTHEAST OF THE AREA AND RISING
HEIGHTS ALOFT USHER IN A SURFACE RIDGE. WITH A WARM MARCH SUN AND
A MODERATING TEMP PROFILE...RELATIVELY PLEASANT CONDITIONS IN THE
LOW TO MID 30S WILL BE OBSERVED. ALTHOUGH...DO EXPECT THIS TO BE
RATHER BRIEF AS FOCUS THEN SHIFTS TOWARDS THE APPROACHING SYSTEM
FOR THE START OF THE WEEK.
AS WAS MENTIONED ABOVE...AM GETTING A LITTLE MORE CONCERNED AT THE
POSSIBILITY FOR A SIGNIFICANT SNOWFALL ACROSS A PORTION OF THE CWA
MONDAY NIGHT INTO TUESDAY NIGHT. THE SYSTEM WHICH WE HAVE
CONTINUED TO MONITOR OVER THE LAST SEVERAL DAYS HAS STARTED TO
BECOME MORE CONSISTENT AMONG VARIOUS MODEL GUIDANCE. DESPITE THE
FACT THAT THERE ARE STILL SOME TIMING AND EXACT PLACEMENT
ISSUES...CONSENSUS IS GROWING FOR A STRONG SYSTEM TO AFFECT
NORTHERN ILLINOIS AND NORTHWEST INDIANA. A STRONG UPPER LEVEL
SYSTEM IS STILL FORECAST TO SLIDE ACROSS THE NORTHERN PLAINS BY
MONDAY...THEN QUICKLY DIG SOUTHEAST TOWARDS THE MID MISSISSIPPI
VALLEY MONDAY NIGHT INTO TUESDAY. WAA OUT AHEAD OF THIS SYSTEM
WILL SLOWLY BRING PRECIP ACROSS PRIMARILY THE SOUTHWEST PORTIONS
OF THE CWA DURING THE DAY ON MONDAY. WITH SLIGHT WARMING...A MIX
OF LIGHT RAIN OR SNOW WILL BE POSSIBLE FOR AREAS ACROSS THE
SOUTHERN CWA...BUT WITH LIGHT SNOW EXPECTED FURTHER NORTHWEST.
ALTHOUGH...REALLY NOT ANTICIPATING MUCH IN TERMS OF ANY
ACCUMULATION THROUGH MOST OF MONDAY WITH RELATIVELY WARMER TEMPS
IN PLACE. ITS NOT UNTIL LATE MONDAY NIGHT INTO TUESDAY THAT MORE
WIDESPREAD DEVELOPMENT WILL SHIFT EAST ACROSS THE CWA. DO EXPECT
ALL SNOW FOR THIS INITIAL TIME FRAME WITH LARGE SCALE LIFT RAPIDLY
COOLING THE TEMP PROFILE ACROSS THE AREA. LARGE SCALE FORCING
INCREASES...AND REALLY GETS GOING ON TUESDAY AS THIS UPPER LEVEL
LOW SHIFTS SOUTHEAST AND THE CWA LIKELY OBSERVES PERIODS OF
PERSISTENT WAA...WITH LIKELY AREAS OF DEFORMATION TO PIVOT ACROSS
THE CWA. ABUNDANT MOISTURE WILL BE PRESENT AND IS SEEN WITH THE
QPF THAT MODEL GUIDANCE IS DEVELOPING...WHICH SEEMS LIKE A VALID
SOLUTION GIVEN THE STRENGTH OF THIS DYNAMIC SYSTEM. WIDESPREAD
SNOW ACCUMULATION IS APPEARING MORE PROBABLE ACROSS THE ENTIRE CWA
TUESDAY INTO TUESDAY NIGHT AND AT THIS TIME...MORE SIGNIFICANT
SNOWFALL POSSIBLY IN EXCESS OF 6 INCHES IS PROBABLE FOR AREAS
SOUTH OF INTERSTATE 80. THIS SYSTEM WILL DEFINITELY NEED TO BE
MONITORED WITH SUCCESSIVE FORECASTS AS GUIDANCE COULD CONTINUE TO
VARY. NONETHELESS...IT IS APPEARING THAT THE REGION AND A PORTION
OF OUR AREA IN NORTHEAST ILLINOIS AND NORTHWEST INDIANA COULD
OBSERVE A SIGNIFICANT SNOW ACCUMULATION WITH WIDESPREAD IMPACTS
LATE MONDAY NIGHT INTO TUESDAY NIGHT. GIVEN THE TIME RANGE OF THE
EVENT AND POSSIBLE RANGE OF SOLUTIONS...HAVE HELD OFF ON ANY
HEADLINES BUT WILL CONTINUE TO MONITOR THIS POTENTIAL.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* NONE.
MDB
//DISCUSSION...UPDATED 00Z...
HIGH PRESSURE STRETCHED ACROSS THE MISSISSIPPI RIVER VALLEY WILL
DRIFT EASTWARD THROUGH THE TAF PERIOD BRINGING DIMINISHING WINDS
AND VFR CONDITIONS. LAKE EFFECT SNOW SHOWERS ARE CONTINUING ACROSS
NW INDIANA EAST OF GYY AND WILL LIKELY CONTINUE THROUGH MUCH OF
THE NIGHT. THERE IS SOME POTENTIAL THAT GYY DOES GET SKIRTED BY
SOME SNOW SHOWERS LATER THIS EVENING OR OVERNIGHT AS LAKE EFFECT
TRIES TO BECOME SOMEWHAT BETTER ORGANIZED BUT CONFIDENCE IS TOO
LOW TO INCLUDE ANY MENTION IN THE TAF AT THIS TIME. MAY ULTIMATELY
NEED TO RE-INTRODUCE BKN SKY COVERAGE WHICH COULD BE HIGH END
MVFR BUT AT THIS POINT AM THINKING THE CIGS/SNOW SHOWERS WILL
REMAIN JUST TO THE EAST. OTHERWISE...WINDS WILL DIMINISH THROUGH
THE EVENING WITH SOME SCATTERED LAKE CLOUDS SKIRTING THE ILLINOIS
SHORELINE. WINDS WILL REMAIN NORTHERLY IN THE 6 TO PERHAPS 10 KT
RANGE SUNDAY THEN SHIFT NORTHEASTERLY LATE IN THE DAY AS THE HIGH
CRESTS THE AREA. SOME SPOTTY MID AND HIGH CLOUD COVER IS ALL THAT
IS EXPECTED SUNDAY.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* NONE.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...INCREASING SNOW AND MVFR CHANCES MONDAY NIGHT.
TUESDAY...SNOW AND IFR LIKELY.
WEDNESDAY...LINGERING LIGHT SNOW/MVFR BECOMING VFR.
THURSDAY AND FRIDAY...VFR.
MDB
&&
.MARINE...
400 PM CST
NORTH WINDS WILL CONTINUE TO GRADUALLY DIMINISH TO A MODERATE
BREEZE TONIGHT AND SUNDAY AS A RIDGE OF HIGH PRESSURE EXTENDING
FROM HUDSON BAY TO THE SOUTHERN PLAINS MOVES SLOWLY EASTWARD...
REACHING LAKE SUPERIOR...EASTERN WISCONSIN AND ILLINOIS...AND
THE LOWER OHIO VALLEY BY SUNDAY NIGHT. LIGHT BREEZES WILL
INCREASE TO MODERATE NORTHEAST AND EAST BREEZES DURING MONDAY
AND MONDAY NIGHT AS LOW PRESSURE MOVES EAST ACROSS THE CENTRAL
PLAINS TO THE LOWER OHIO VALLEY. AS THE LOW CONTINUES MOVING
OFF TO THE EAST MONDAY NIGHT THROUGH WEDNESDAY WINDS ON LAKE MI
WILL BACK TO OUT OF THE NORTHEAST AND NORTH WHILE FRESHENING TO
STRONG BREEZES. DURING WEDNESDAY AND WEDNESDAY ANOTHER RIDGE OF
HIGH PRESSURE WILL BE MOVING EAST TO ONTARIO... THE UPPER GREAT
LAKES...AND THE MID AND LOWER MS VALLEY ALLOWING WINDS TO
GRADUALLY SLACKEN TO A LIGHT BREEZE AGAIN.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 10 PM SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM
SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
223 PM CST FRI MAR 1 2013
.DISCUSSION...
919 AM CST
UPDATED THE GRIDS FOR THIS MORNING...MAINLY TO ACCOUNT FOR ONGOING
LAKE EFFECT SNOW SHOWERS.
LATEST RADAR IMAGERY DEPICTING SOME LIGHT RETURNS ACROSS ALL OF
NORTHERN ILLINOIS WITH AN ISOLATED AREA OF FAIRLY DECENT
RETURNS...PRIMARILY ACROSS SOUTHEAST COOK COUNTY AND NORTHWEST
LAKE COUNTY IN INDIANA. UNDER THE LIGHTER RETURNS LIGHT SNOW
CONTINUES WITH VIS STAYING CONFINED TO ONLY THE 3-6 MILE
RANGE...WITH VIS LIKELY AT OR UNDER 1 MILE UNDER THE STRONGER
RETURNS. THESE SNOW SHOWERS ARE IN RESPONSE TO PERSISTENT
NORTH/NORTHEAST FLOW OFF OF A MODERATELY UNSTABLE LAKE...AS WELL
AS WEAK LARGE SCALE LIFT. LATEST SURFACE ANALYSIS INDICATING A
SURFACE TROUGH SITUATED ACROSS THE SOUTHERN HALF OF THE
LAKE...EXTENDING BACK NORTHWEST FROM A WEAK SURFACE LOW OVER
IN/KY. THIS HAS RESULTED IN AN AREA OF BETTER CONVERGENCE THIS
MORNING...WHICH HAS THEN PROVIDED THIS ISOLATED AREA OF STRONGER
SNOW SHOWERS. LATEST SHORT TERM GUIDANCE IS INDICATING THIS TROUGH
TO SLOWLY EXIT/DAMPEN WITH ALL SURFACE WINDS BECOMING MORE
NORTHERLY...AND LOSS OF BETTER CONVERGENCE. SO DO EXPECT THIS
ISOLATED AREA OF STRONGER SNOW SHOWERS TO PERSIST OVER THE NEXT
COUPLE OF HOURS...ONCE AGAIN PRIMARILY AFFECTING ONLY SOUTHEAST
COOK AND NORTHWEST LAKE COUNTY IN INDIANA. UNDER THESE STRONGER
RETURNS IT WOULD NOT BE OUT OF THE QUESTION FOR SOME ADDITIONAL
ACCUMULATIONS...WITH 1 TO 3 INCHES NOT OF THE REALM OF
POSSIBILITY THROUGH MID DAY. LIGHT SNOW SHOWERS ARE THEN EXPECTED
TO CONTINUE INTO THE AFTERNOON...BUT WITH ONLY LIGHT ACCUMULATIONS
ANTICIPATED.
RODRIGUEZ
//PREV DISCUSSION...
330 AM CST
FORECAST CONCERNS ARE LAKE EFFECT SNOW SHOWER POTENTIAL THE NEXT FEW
DAYS...COLD TEMPERATURES OVER THE WEEKEND...AND A POSSIBLE SNOW
PRODUCING SYSTEM EARLY NEXT WEEK.
SHORT TERM...TODAY THROUGH SUNDAY NIGHT...
SLIGHTLY COLDER AIR MASS WILL SETTLE OVER THE REGION TODAY ON
CONTINUED NORTHERLY FLOW...WITH A LARGE AREA OF HIGH PRESSURE
BUILDING IN FROM THE NORTH. THIS SHOULD KEEP HIGHS A FEW DEGREES
COOLER THAN YESTERDAY. LAKE EFFECT SET UP IS QUITE MARGINAL
THERMODYNAMICALLY...BUT COMPENSATING SOMEWHAT WILL BE GOOD
CONVERGENCE AND FETCH WITH NORTH-NORTHEAST LOW LEVEL FLOW. THE
CONVERGENCE AND EVEN SOME ENHANCED LIFT IS BEST ALIGNED OVER
ILLINOIS AND PORTION OF NW INDIANA LAKEFRONT THROUGH MID/LATE
MORNING...SO BUMPED UP POPS SOME FROM PREVIOUS FORECAST. COULD SEE
SOME VERY LIGHT ACCUMULATIONS. OUTSIDE OF LAKE EFFECT...THERE MAY BE
SOME FLURRIES INLAND. ALTHOUGH STRATUS CAN CLEAR OUT QUICKER THIS
TIME OF YEAR DUE TO HIGHER SUN ANGLE...THINK THE NAM IS BEING WAY
TOO AGGRESSIVE WITH CLEARING TREND FROM NORTH. USED RAP GUIDANCE FOR
NEAR TERM SKY FORECAST. MOST OF CWA SHOULD SEE OVC THROUGH DAYLIGHT
HOURS.
THE SAME GENERAL IDEA OF DECENT CONVERGENCE BUT VERY MARGINAL
THERMODYNAMICS AND INVERSION HEIGHTS CONTINUES THROUGH SATURDAY WITH
THE LAKE EFFECT. WILL CONTINUE TO CARRY CHANCE POPS...THOUGH THEY
WILL SLIDE INTO NW INDIANA ON SATURDAY AS NORTHERLY FLOW BECOMES
JUST WEST OF DUE NORTH. SKIES SHOULD START TO CLEAR BY DAYBREAK OVER
THE NW CWA...SO TEMPERATURES SHOULD DROP PRETTY WELL THERE GIVEN
THE GOOD RADIATION COOLING...PROBABLY INTO THE MID TEENS.
OUTSIDE OF LAKE EFFECT CONCERNS...THE ONLY FOCUS OVER THE WEEKEND
WAS TEMPERATURES WITH HIGH PRESSURE BUILDING OVERHEAD. FOR HIGHS
ON SATURDAY...SUSPECT THAT THE MARCH SUN WILL GO TO WORK ON THE
SNOW COVER...ESPECIALLY FOR AREAS THAT DIDNT SEE MUCH THIS WEEK.
FOR MARCH 1-15...WITH 850 TEMPS AROUND -10C AS IS PROGGED ON
SATURDAY...MEDIAN HIGH AT ORD IS 34 DEGREES. WENT JUST UNDER THAT
IN NORTHERN CWA/ESPECIALLY IN THE NORTHEAST WHERE SNOW PACK IS
DEEPEST...YIELDING HIGHS AROUND 30. TO THE SOUTH OF I-80...SUSPECT
WE`LL SEE SOME MID TO EVEN UPPER 30S AS SUN EATS AWAY AT MEAGER
SNOW COVER.
THEN SUNDAY NIGHT...THERE IS A STRONG SIGNAL FOR GOOD RADIATIONAL
COOLING...ESPECIALLY ON THE ECMWF...WHICH MAY BE A BIT TOO
AGGRESSIVE WITH ITS ZERO TO SLIGHTLY BELOW ZERO NUMBERS FOR NORTH
CENTRAL IL. BASICALLY CONTINUED IDEA OF PREVIOUS FORECAST WITH
POTENTIAL FOR SINGLE DIGIT LOWS WEST OF FOX RIVER. ON SUNDAY...THE
COLD START MAY KEEP TEMPS IN CHECK SOMEWHAT...BUT MARCH SUN ANGLE
AND LONGER DAYLIGHT HOURS EXPECTED TO COMPENSATE...IN ADDITION TO
SLIGHTLY WARMER TEMPS ALOFT. MEDIAN ORD HIGHS FOR DAYS WITH 850
TEMPS AS PROGGED ON SUNDAY IN -6 TO -8 RANGE IS 38. DIDNT GO THIS
MILD DUE TO COLD START AND SNOW COVER OVER NORTHERN CWA...BUT
BUMPED UP TEMPS A FEW DEGREES FROM PREVIOUS. IF SNOW COVER CAN BE
ELIMINATED ON SATURDAY OVER SOUTH...WOULDNT BE SURPRISED IF SOME
LOCATIONS TAG 40 DEGREES...BUT FOR NOW WENT WITH UPPER 30S IN
CENTRAL IL. INCREASING CLOUD COVER SHOULD RESULT IN LOWS SEVERAL
DEGREES WARMER SUNDAY NIGHT THAN SATURDAY NIGHT.
LONG TERM...MONDAY THROUGH THURSDAY
MAIN FOCUS IS ON VERY ENERGETIC CLIPPER SYSTEM EARLY NEXT WEEK.
THERE HAVE BEEN FAIRLY SIGNIFICANT RUN TO RUN CHANGES WITH THE
TIMING AND TRACK OF THE STRONG UPPER LOW AND SURFACE REFLECTION.
WOULD EXPECT THIS TO CONTINUE UNTIL UPPER WAVE MAKES LANDFALL IN
PACIFIC NORTHWEST SATURDAY NIGHT ALLOWING FOR SAMPLING BY RAOB
NETWORK. AS IT STANDS RIGHT NOW...00Z GUIDANCE HAS SHIFTED BACK
NORTH...WHICH WOULD PUT MOST OF CWA IN LINE FOR A POTENTIALLY
ACCUMULATING SNOW. COULD SEE THE START OF SOME WAA SNOWS AHEAD OF
SYSTEM ON MONDAY...SO BLENDED POPS WERE MAINTAINED.
HOWEVER...BIGGEST CHANGE WAS TO GREATLY INCREASE POPS ABOVE
ALLBLEND MONDAY NIGHT AND TUESDAY IN LINE WITH A SLOWER
PROGRESSION OF THE UPPER LOW AND ATTENDANT SURFACE LOW FAVORED BY
THE 00Z ECMWF...CANADIAN...GEFS AND HPC. GFS APPEARS MUCH TOO FAST
IN CLEARING THE SYSTEM OFF TO THE EAST. FOR NOW...BUMPED UP POPS
TO MID RANGE CHANCE GIVEN UNCERTAINTY.
AS CURRENTLY MODELED...THE UPPER LOW WITH THIS SYSTEM LOOKS QUITE
STRONG...WITH A TIGHT BAROCLINIC ZONE ALONG/AHEAD OF ITS TRACK. THUS
THERE COULD BE A NICE SWATH OF SNOW PUT DOWN SOMEWHERE OVER/NEAR THE
REGION. ON THE NEGATIVE SIDE...TEMPERATURES AS IS USUALLY THE CASE
IN MARCH WOULD BE NEAR FREEZING...SO THE SNOW WOULD HAVE TO COME
DOWN HARD TO ACCUMULATE EFFICIENTLY. LOTS OF TIME TO MONITOR THIS
SYSTEM.
FOR THE REST OF THE EXTENDED AND BEYOND...AFTER A FAIRLY COOL DAY ON
WEDNESDAY BEHIND THE EARLY WEEK SYSTEM...THERE COULD BE BRIEF WARM UP
TO NORMAL TO ABOVE NORMAL AS THE PATTERN TRANSITIONS FROM AN EASTERN
TROUGH/WESTERN RIDGE (POSITIVE PNA) CONFIGURATION TO A WESTERN
TROUGH/EASTERN RIDGE (NEGATIVE PNA) PATTERN. WITH RIDGING FIRST
AMPLIFYING INTO CENTER OF CONUS...WE COULD SEE A FEW DAYS OF
TEMPERATURES AT LEAST BACK INTO THE 40S.
HOWEVER...THE LONG RANGE ENSEMBLES LOOKING BEYOND THIS 7 DAY
FORECAST PERIOD ARE HOLDING ONTO THE IDEA OF MAINTAINING HIGH
LATITUDE BLOCKING/NEGATIVE NAO AND NEGATIVE AO THROUGH MID MARCH.
IN ADDITION...RIDGING MAY AMPLIFY OVER OR NEAR ALASKA WHICH ALLOWS
FRESH COLD AIR TO INFILTRATE CANADA AND THE NORTHERN CONUS. BOTTOM
LINE IS ANY WARM UP COULD BE QUICKLY FOLLOWED BY A RETURN TO THE
COLDER THAN NORMAL PATTERN. NO MARCH 2012 PATTERN IS SEEN IN THE
EXTENDED FOR ANYONE HOPING FOR AN EARLY SUMMER AGAIN.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LOW MVFR CIGS IN THE 1000-1500 FT RANGE THIS AFTERNOON.
* LAKE EFFECT SNOW SHOWERS POSSIBLE AGAIN TONIGHT...LOWER MVFR VIS
POSSIBLE.
KJB
//DISCUSSION...UPDATED 18Z...
THE LAKE EFFECT SNOW SHOWER ACTIVITY CONTINUES TO ABATE ACROSS THE
TERMINALS EARLY THIS AFTERNOON AS THE LOWER LEVEL CONVERGENCE WEAKENS
IN RESPONSE TO AN INVERTED SURFACE TROUGH MOVING ONSHORE ACROSS
NORTHEASTERN ILLINOIS. WINDS ARE BECOMING NORTH-NORTHEASTERLY IN
THE WAKE OF THIS SURFACE TROUGH...AND I EXPECT ALL OF THE EASTERN
TERMINALS TO BE 010-020 BY OR SHORTLY AFTER 18 UTC. ANY ADDITIONAL
SNOW SHOWER ACTIVITY THIS AFTERNOON LOOKS TO BE VERY LIGHT...WITH
MINIMAL IMPACTS TO THE VISIBILITY EXPECTED.
THE SURFACE FLOW WILL REMAIN OUT OF THE NORTH NORTHEAST INTO
SATURDAY AS A SURFACE RIDGE OF HIGH PRESSURE CONTINUES TO BUILD
EASTWARD ACROSS THE REGION. SOME ADDITIONAL LAKE EFFECT SNOW
SHOWER ACTIVITY IS POSSIBLY TONIGHT ACROSS THE EASTERN TERMINALS
AS THE LAKESHORE CONVERGENCE INCREASES IN RESPONSE TO A LAND BREEZE.
HOWEVER...THE OVERALL THERMODYNAMIC SETUP IS SLOWLY BECOMING
SLIGHTLY LESS FAVORABLE FOR LAKE EFFECT SNOW. THUS ONLY SOME MVFR
VIS IS CURRENTLY EXPECTED...WITH A SMALL POSSIBILITY OF A SHORT
PERIOD OF LOWER VIS NOT OUT OF THE QUESTION TONIGHT.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* LOW TO MEDIUM CONFIDENCE ON ADDITIONAL LAKE EFFECT SNOW SHOWERS TONIGHT.
* HIGH CONFIDENCE IN LOW MVFR CIGS THROUGH THE AFTERNOON.
KJB
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...MVFR CIGS POSSIBLE EARLY.
SUNDAY...VFR.
MONDAY...CHANCE OF LIGHT SNOW IN THE AFTERNOON. MVFR POSSIBLE
LATE.
MONDAY NIGHT INTO TUESDAY...GOOD CHANCE OF SNOW. IFR PROBABLE.
WEDNESDAY...MVFR CIGS POSSIBLE.
THURSDAY...VFR EXPECTED.
IZZI
&&
.MARINE...
222 PM CST
NORTH WINDS WILL CONTINUE TO GRADUALLY DIMINISH TONIGHT THROUGH
SUNDAY AS A LOW IN THE NORTH ATLANTIC EAST OF THE CANADIAN
MARITIMES CONTINUES TO MOVE FURTHER OUT TO SEA. THIS ALLOWS A
RIDGE OF HIGH PRESSURE TO GRADUALLY SHIFT EASTWARD FROM THE
PLAINS...BUT THE RIDGE WILL NOT REACH LAKE MI UNTIL LATER
SATURDAY AND SATURDAY EVENING RESULTING IN PERIOD OF LIGHT
VARIABLE WINDS BEFORE BECOMING EAST AND SOUTHEAST BY MONDAY
MORNING AS THE RIDGE CONTINUES ITS SLOW DRIFT TO THE EAST INTO
THE CENTRAL GREAT LAKES AND A LOW MOVES FROM THE ROCKIES OVER THE
HIGH PLAINS TO THE CENTRAL PLAINS. THE SOUTHEAST AND EAST WINDS
WILL BE INCREASING TO MODERATE BREEZES BY MONDAY AS THE LOW
CONTINUES EAST TO THE LOWER OH VALLEY REGION.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 AM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 9 AM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
147 PM CST FRI MAR 1 2013
.DISCUSSION...
919 AM CST
UPDATED THE GRIDS FOR THIS MORNING...MAINLY TO ACCOUNT FOR ONGOING
LAKE EFFECT SNOW SHOWERS.
LATEST RADAR IMAGERY DEPICTING SOME LIGHT RETURNS ACROSS ALL OF
NORTHERN ILLINOIS WITH AN ISOLATED AREA OF FAIRLY DECENT
RETURNS...PRIMARILY ACROSS SOUTHEAST COOK COUNTY AND NORTHWEST
LAKE COUNTY IN INDIANA. UNDER THE LIGHTER RETURNS LIGHT SNOW
CONTINUES WITH VIS STAYING CONFINED TO ONLY THE 3-6 MILE
RANGE...WITH VIS LIKELY AT OR UNDER 1 MILE UNDER THE STRONGER
RETURNS. THESE SNOW SHOWERS ARE IN RESPONSE TO PERSISTENT
NORTH/NORTHEAST FLOW OFF OF A MODERATELY UNSTABLE LAKE...AS WELL
AS WEAK LARGE SCALE LIFT. LATEST SURFACE ANALYSIS INDICATING A
SURFACE TROUGH SITUATED ACROSS THE SOUTHERN HALF OF THE
LAKE...EXTENDING BACK NORTHWEST FROM A WEAK SURFACE LOW OVER
IN/KY. THIS HAS RESULTED IN AN AREA OF BETTER CONVERGENCE THIS
MORNING...WHICH HAS THEN PROVIDED THIS ISOLATED AREA OF STRONGER
SNOW SHOWERS. LATEST SHORT TERM GUIDANCE IS INDICATING THIS TROUGH
TO SLOWLY EXIT/DAMPEN WITH ALL SURFACE WINDS BECOMING MORE
NORTHERLY...AND LOSS OF BETTER CONVERGENCE. SO DO EXPECT THIS
ISOLATED AREA OF STRONGER SNOW SHOWERS TO PERSIST OVER THE NEXT
COUPLE OF HOURS...ONCE AGAIN PRIMARILY AFFECTING ONLY SOUTHEAST
COOK AND NORTHWEST LAKE COUNTY IN INDIANA. UNDER THESE STRONGER
RETURNS IT WOULD NOT BE OUT OF THE QUESTION FOR SOME ADDITIONAL
ACCUMULATIONS...WITH 1 TO 3 INCHES NOT OF THE REALM OF
POSSIBILITY THROUGH MID DAY. LIGHT SNOW SHOWERS ARE THEN EXPECTED
TO CONTINUE INTO THE AFTERNOON...BUT WITH ONLY LIGHT ACCUMULATIONS
ANTICIPATED.
RODRIGUEZ
//PREV DISCUSSION...
330 AM CST
FORECAST CONCERNS ARE LAKE EFFECT SNOW SHOWER POTENTIAL THE NEXT FEW
DAYS...COLD TEMPERATURES OVER THE WEEKEND...AND A POSSIBLE SNOW
PRODUCING SYSTEM EARLY NEXT WEEK.
SHORT TERM...TODAY THROUGH SUNDAY NIGHT...
SLIGHTLY COLDER AIR MASS WILL SETTLE OVER THE REGION TODAY ON
CONTINUED NORTHERLY FLOW...WITH A LARGE AREA OF HIGH PRESSURE
BUILDING IN FROM THE NORTH. THIS SHOULD KEEP HIGHS A FEW DEGREES
COOLER THAN YESTERDAY. LAKE EFFECT SET UP IS QUITE MARGINAL
THERMODYNAMICALLY...BUT COMPENSATING SOMEWHAT WILL BE GOOD
CONVERGENCE AND FETCH WITH NORTH-NORTHEAST LOW LEVEL FLOW. THE
CONVERGENCE AND EVEN SOME ENHANCED LIFT IS BEST ALIGNED OVER
ILLINOIS AND PORTION OF NW INDIANA LAKEFRONT THROUGH MID/LATE
MORNING...SO BUMPED UP POPS SOME FROM PREVIOUS FORECAST. COULD SEE
SOME VERY LIGHT ACCUMULATIONS. OUTSIDE OF LAKE EFFECT...THERE MAY BE
SOME FLURRIES INLAND. ALTHOUGH STRATUS CAN CLEAR OUT QUICKER THIS
TIME OF YEAR DUE TO HIGHER SUN ANGLE...THINK THE NAM IS BEING WAY
TOO AGGRESSIVE WITH CLEARING TREND FROM NORTH. USED RAP GUIDANCE FOR
NEAR TERM SKY FORECAST. MOST OF CWA SHOULD SEE OVC THROUGH DAYLIGHT
HOURS.
THE SAME GENERAL IDEA OF DECENT CONVERGENCE BUT VERY MARGINAL
THERMODYNAMICS AND INVERSION HEIGHTS CONTINUES THROUGH SATURDAY WITH
THE LAKE EFFECT. WILL CONTINUE TO CARRY CHANCE POPS...THOUGH THEY
WILL SLIDE INTO NW INDIANA ON SATURDAY AS NORTHERLY FLOW BECOMES
JUST WEST OF DUE NORTH. SKIES SHOULD START TO CLEAR BY DAYBREAK OVER
THE NW CWA...SO TEMPERATURES SHOULD DROP PRETTY WELL THERE GIVEN
THE GOOD RADIATION COOLING...PROBABLY INTO THE MID TEENS.
OUTSIDE OF LAKE EFFECT CONCERNS...THE ONLY FOCUS OVER THE WEEKEND
WAS TEMPERATURES WITH HIGH PRESSURE BUILDING OVERHEAD. FOR HIGHS
ON SATURDAY...SUSPECT THAT THE MARCH SUN WILL GO TO WORK ON THE
SNOW COVER...ESPECIALLY FOR AREAS THAT DIDNT SEE MUCH THIS WEEK.
FOR MARCH 1-15...WITH 850 TEMPS AROUND -10C AS IS PROGGED ON
SATURDAY...MEDIAN HIGH AT ORD IS 34 DEGREES. WENT JUST UNDER THAT
IN NORTHERN CWA/ESPECIALLY IN THE NORTHEAST WHERE SNOW PACK IS
DEEPEST...YIELDING HIGHS AROUND 30. TO THE SOUTH OF I-80...SUSPECT
WE`LL SEE SOME MID TO EVEN UPPER 30S AS SUN EATS AWAY AT MEAGER
SNOW COVER.
THEN SUNDAY NIGHT...THERE IS A STRONG SIGNAL FOR GOOD RADIATIONAL
COOLING...ESPECIALLY ON THE ECMWF...WHICH MAY BE A BIT TOO
AGGRESSIVE WITH ITS ZERO TO SLIGHTLY BELOW ZERO NUMBERS FOR NORTH
CENTRAL IL. BASICALLY CONTINUED IDEA OF PREVIOUS FORECAST WITH
POTENTIAL FOR SINGLE DIGIT LOWS WEST OF FOX RIVER. ON SUNDAY...THE
COLD START MAY KEEP TEMPS IN CHECK SOMEWHAT...BUT MARCH SUN ANGLE
AND LONGER DAYLIGHT HOURS EXPECTED TO COMPENSATE...IN ADDITION TO
SLIGHTLY WARMER TEMPS ALOFT. MEDIAN ORD HIGHS FOR DAYS WITH 850
TEMPS AS PROGGED ON SUNDAY IN -6 TO -8 RANGE IS 38. DIDNT GO THIS
MILD DUE TO COLD START AND SNOW COVER OVER NORTHERN CWA...BUT
BUMPED UP TEMPS A FEW DEGREES FROM PREVIOUS. IF SNOW COVER CAN BE
ELIMINATED ON SATURDAY OVER SOUTH...WOULDNT BE SURPRISED IF SOME
LOCATIONS TAG 40 DEGREES...BUT FOR NOW WENT WITH UPPER 30S IN
CENTRAL IL. INCREASING CLOUD COVER SHOULD RESULT IN LOWS SEVERAL
DEGREES WARMER SUNDAY NIGHT THAN SATURDAY NIGHT.
LONG TERM...MONDAY THROUGH THURSDAY
MAIN FOCUS IS ON VERY ENERGETIC CLIPPER SYSTEM EARLY NEXT WEEK.
THERE HAVE BEEN FAIRLY SIGNIFICANT RUN TO RUN CHANGES WITH THE
TIMING AND TRACK OF THE STRONG UPPER LOW AND SURFACE REFLECTION.
WOULD EXPECT THIS TO CONTINUE UNTIL UPPER WAVE MAKES LANDFALL IN
PACIFIC NORTHWEST SATURDAY NIGHT ALLOWING FOR SAMPLING BY RAOB
NETWORK. AS IT STANDS RIGHT NOW...00Z GUIDANCE HAS SHIFTED BACK
NORTH...WHICH WOULD PUT MOST OF CWA IN LINE FOR A POTENTIALLY
ACCUMULATING SNOW. COULD SEE THE START OF SOME WAA SNOWS AHEAD OF
SYSTEM ON MONDAY...SO BLENDED POPS WERE MAINTAINED.
HOWEVER...BIGGEST CHANGE WAS TO GREATLY INCREASE POPS ABOVE
ALLBLEND MONDAY NIGHT AND TUESDAY IN LINE WITH A SLOWER
PROGRESSION OF THE UPPER LOW AND ATTENDANT SURFACE LOW FAVORED BY
THE 00Z ECMWF...CANADIAN...GEFS AND HPC. GFS APPEARS MUCH TOO FAST
IN CLEARING THE SYSTEM OFF TO THE EAST. FOR NOW...BUMPED UP POPS
TO MID RANGE CHANCE GIVEN UNCERTAINTY.
AS CURRENTLY MODELED...THE UPPER LOW WITH THIS SYSTEM LOOKS QUITE
STRONG...WITH A TIGHT BAROCLINIC ZONE ALONG/AHEAD OF ITS TRACK. THUS
THERE COULD BE A NICE SWATH OF SNOW PUT DOWN SOMEWHERE OVER/NEAR THE
REGION. ON THE NEGATIVE SIDE...TEMPERATURES AS IS USUALLY THE CASE
IN MARCH WOULD BE NEAR FREEZING...SO THE SNOW WOULD HAVE TO COME
DOWN HARD TO ACCUMULATE EFFICIENTLY. LOTS OF TIME TO MONITOR THIS
SYSTEM.
FOR THE REST OF THE EXTENDED AND BEYOND...AFTER A FAIRLY COOL DAY ON
WEDNESDAY BEHIND THE EARLY WEEK SYSTEM...THERE COULD BE BRIEF WARM UP
TO NORMAL TO ABOVE NORMAL AS THE PATTERN TRANSITIONS FROM AN EASTERN
TROUGH/WESTERN RIDGE (POSITIVE PNA) CONFIGURATION TO A WESTERN
TROUGH/EASTERN RIDGE (NEGATIVE PNA) PATTERN. WITH RIDGING FIRST
AMPLIFYING INTO CENTER OF CONUS...WE COULD SEE A FEW DAYS OF
TEMPERATURES AT LEAST BACK INTO THE 40S.
HOWEVER...THE LONG RANGE ENSEMBLES LOOKING BEYOND THIS 7 DAY
FORECAST PERIOD ARE HOLDING ONTO THE IDEA OF MAINTAINING HIGH
LATITUDE BLOCKING/NEGATIVE NAO AND NEGATIVE AO THROUGH MID MARCH.
IN ADDITION...RIDGING MAY AMPLIFY OVER OR NEAR ALASKA WHICH ALLOWS
FRESH COLD AIR TO INFILTRATE CANADA AND THE NORTHERN CONUS. BOTTOM
LINE IS ANY WARM UP COULD BE QUICKLY FOLLOWED BY A RETURN TO THE
COLDER THAN NORMAL PATTERN. NO MARCH 2012 PATTERN IS SEEN IN THE
EXTENDED FOR ANYONE HOPING FOR AN EARLY SUMMER AGAIN.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LOW MVFR CIGS IN THE 1000-1500 FT RANGE THIS AFTERNOON.
* LAKE EFFECT SNOW SHOWERS POSSIBLE AGAIN TONIGHT...LOWER MVFR VIS
POSSIBLE.
KJB
//DISCUSSION...UPDATED 18Z...
THE LAKE EFFECT SNOW SHOWER ACTIVITY CONTINUES TO ABATE ACROSS THE
TERMINALS EARLY THIS AFTERNOON AS THE LOWER LEVEL CONVERGENCE WEAKENS
IN RESPONSE TO AN INVERTED SURFACE TROUGH MOVING ONSHORE ACROSS
NORTHEASTERN ILLINOIS. WINDS ARE BECOMING NORTH-NORTHEASTERLY IN
THE WAKE OF THIS SURFACE TROUGH...AND I EXPECT ALL OF THE EASTERN
TERMINALS TO BE 010-020 BY OR SHORTLY AFTER 18 UTC. ANY ADDITIONAL
SNOW SHOWER ACTIVITY THIS AFTERNOON LOOKS TO BE VERY LIGHT...WITH
MINIMAL IMPACTS TO THE VISIBILITY EXPECTED.
THE SURFACE FLOW WILL REMAIN OUT OF THE NORTH NORTHEAST INTO
SATURDAY AS A SURFACE RIDGE OF HIGH PRESSURE CONTINUES TO BUILD
EASTWARD ACROSS THE REGION. SOME ADDITIONAL LAKE EFFECT SNOW
SHOWER ACTIVITY IS POSSIBLY TONIGHT ACROSS THE EASTERN TERMINALS
AS THE LAKESHORE CONVERGENCE INCREASES IN RESPONSE TO A LAND BREEZE.
HOWEVER...THE OVERALL THERMODYNAMIC SETUP IS SLOWLY BECOMING
SLIGHTLY LESS FAVORABLE FOR LAKE EFFECT SNOW. THUS ONLY SOME MVFR
VIS IS CURRENTLY EXPECTED...WITH A SMALL POSSIBILITY OF A SHORT
PERIOD OF LOWER VIS NOT OUT OF THE QUESTION TONIGHT.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* LOW TO MEDIUM CONFIDENCE ON ADDITIONAL LAKE EFFECT SNOW SHOWERS TONIGHT.
* HIGH CONFIDENCE IN LOW MVFR CIGS THROUGH THE AFTERNOON.
KJB
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...MVFR CIGS POSSIBLE EARLY.
SUNDAY...VFR.
MONDAY...CHANCE OF LIGHT SNOW IN THE AFTERNOON. MVFR POSSIBLE
LATE.
MONDAY NIGHT INTO TUESDAY...GOOD CHANCE OF SNOW. IFR PROBABLE.
WEDNESDAY...MVFR CIGS POSSIBLE.
THURSDAY...VFR EXPECTED.
IZZI
&&
.MARINE...
222 AM CST
MODERATELY STRONG NORTH WINDS LIKELY TO CONTINUE THROUGH SATURDAY
WITH OCCASIONAL GALE FORCE GUSTS A POSSIBILITY...ESPECIALLY LATER
THIS AFTERNOON INTO THE EVENING...BUT GENERALLY THINK ANY GALES
WILL BE INFREQUENT ENOUGH TO KEEP OUT OF THE FORECAST. WINDS WILL
BEGIN TO DIMINISHING LATER SATURDAY INTO SUNDAY AS RIDGE AXIS
APPROACHES AND THEN MOVES ACROSS THE LAKE SUNDAY NIGHT. ANOTHER
SYSTEM WILL PASS TO THE SOUTHWEST OF THE LAKE EARLY/MIDDLE PART OF
NEXT WEEK WITH WINDS FRESHENING UP A BIT...BUT SYSTEM SHOULD BE
WEAK ENOUGH AND FAR ENOUGH AWAY TO NOT CAUSE ANY MAJOR
WINDS/WAVES.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 AM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 9 AM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1146 AM CST FRI MAR 1 2013
.DISCUSSION...
919 AM CST
UPDATED THE GRIDS FOR THIS MORNING...MAINLY TO ACCOUNT FOR ONGOING
LAKE EFFECT SNOW SHOWERS.
LATEST RADAR IMAGERY DEPICTING SOME LIGHT RETURNS ACROSS ALL OF
NORTHERN ILLINOIS WITH AN ISOLATED AREA OF FAIRLY DECENT
RETURNS...PRIMARILY ACROSS SOUTHEAST COOK COUNTY AND NORTHWEST
LAKE COUNTY IN INDIANA. UNDER THE LIGHTER RETURNS LIGHT SNOW
CONTINUES WITH VIS STAYING CONFINED TO ONLY THE 3-6 MILE
RANGE...WITH VIS LIKELY AT OR UNDER 1 MILE UNDER THE STRONGER
RETURNS. THESE SNOW SHOWERS ARE IN RESPONSE TO PERSISTENT
NORTH/NORTHEAST FLOW OFF OF A MODERATELY UNSTABLE LAKE...AS WELL
AS WEAK LARGE SCALE LIFT. LATEST SURFACE ANALYSIS INDICATING A
SURFACE TROUGH SITUATED ACROSS THE SOUTHERN HALF OF THE
LAKE...EXTENDING BACK NORTHWEST FROM A WEAK SURFACE LOW OVER
IN/KY. THIS HAS RESULTED IN AN AREA OF BETTER CONVERGENCE THIS
MORNING...WHICH HAS THEN PROVIDED THIS ISOLATED AREA OF STRONGER
SNOW SHOWERS. LATEST SHORT TERM GUIDANCE IS INDICATING THIS TROUGH
TO SLOWLY EXIT/DAMPEN WITH ALL SURFACE WINDS BECOMING MORE
NORTHERLY...AND LOSS OF BETTER CONVERGENCE. SO DO EXPECT THIS
ISOLATED AREA OF STRONGER SNOW SHOWERS TO PERSIST OVER THE NEXT
COUPLE OF HOURS...ONCE AGAIN PRIMARILY AFFECTING ONLY SOUTHEAST
COOK AND NORTHWEST LAKE COUNTY IN INDIANA. UNDER THESE STRONGER
RETURNS IT WOULD NOT BE OUT OF THE QUESTION FOR SOME ADDITIONAL
ACCUMULATIONS...WITH 1 TO 3 INCHES NOT OF THE REALM OF
POSSIBILITY THROUGH MID DAY. LIGHT SNOW SHOWERS ARE THEN EXPECTED
TO CONTINUE INTO THE AFTERNOON...BUT WITH ONLY LIGHT ACCUMULATIONS
ANTICIPATED.
RODRIGUEZ
//PREV DISCUSSION...
330 AM CST
FORECAST CONCERNS ARE LAKE EFFECT SNOW SHOWER POTENTIAL THE NEXT FEW
DAYS...COLD TEMPERATURES OVER THE WEEKEND...AND A POSSIBLE SNOW
PRODUCING SYSTEM EARLY NEXT WEEK.
SHORT TERM...TODAY THROUGH SUNDAY NIGHT...
SLIGHTLY COLDER AIR MASS WILL SETTLE OVER THE REGION TODAY ON
CONTINUED NORTHERLY FLOW...WITH A LARGE AREA OF HIGH PRESSURE
BUILDING IN FROM THE NORTH. THIS SHOULD KEEP HIGHS A FEW DEGREES
COOLER THAN YESTERDAY. LAKE EFFECT SET UP IS QUITE MARGINAL
THERMODYNAMICALLY...BUT COMPENSATING SOMEWHAT WILL BE GOOD
CONVERGENCE AND FETCH WITH NORTH-NORTHEAST LOW LEVEL FLOW. THE
CONVERGENCE AND EVEN SOME ENHANCED LIFT IS BEST ALIGNED OVER
ILLINOIS AND PORTION OF NW INDIANA LAKEFRONT THROUGH MID/LATE
MORNING...SO BUMPED UP POPS SOME FROM PREVIOUS FORECAST. COULD SEE
SOME VERY LIGHT ACCUMULATIONS. OUTSIDE OF LAKE EFFECT...THERE MAY BE
SOME FLURRIES INLAND. ALTHOUGH STRATUS CAN CLEAR OUT QUICKER THIS
TIME OF YEAR DUE TO HIGHER SUN ANGLE...THINK THE NAM IS BEING WAY
TOO AGGRESSIVE WITH CLEARING TREND FROM NORTH. USED RAP GUIDANCE FOR
NEAR TERM SKY FORECAST. MOST OF CWA SHOULD SEE OVC THROUGH DAYLIGHT
HOURS.
THE SAME GENERAL IDEA OF DECENT CONVERGENCE BUT VERY MARGINAL
THERMODYNAMICS AND INVERSION HEIGHTS CONTINUES THROUGH SATURDAY WITH
THE LAKE EFFECT. WILL CONTINUE TO CARRY CHANCE POPS...THOUGH THEY
WILL SLIDE INTO NW INDIANA ON SATURDAY AS NORTHERLY FLOW BECOMES
JUST WEST OF DUE NORTH. SKIES SHOULD START TO CLEAR BY DAYBREAK OVER
THE NW CWA...SO TEMPERATURES SHOULD DROP PRETTY WELL THERE GIVEN
THE GOOD RADIATION COOLING...PROBABLY INTO THE MID TEENS.
OUTSIDE OF LAKE EFFECT CONCERNS...THE ONLY FOCUS OVER THE WEEKEND
WAS TEMPERATURES WITH HIGH PRESSURE BUILDING OVERHEAD. FOR HIGHS
ON SATURDAY...SUSPECT THAT THE MARCH SUN WILL GO TO WORK ON THE
SNOW COVER...ESPECIALLY FOR AREAS THAT DIDNT SEE MUCH THIS WEEK.
FOR MARCH 1-15...WITH 850 TEMPS AROUND -10C AS IS PROGGED ON
SATURDAY...MEDIAN HIGH AT ORD IS 34 DEGREES. WENT JUST UNDER THAT
IN NORTHERN CWA/ESPECIALLY IN THE NORTHEAST WHERE SNOW PACK IS
DEEPEST...YIELDING HIGHS AROUND 30. TO THE SOUTH OF I-80...SUSPECT
WE`LL SEE SOME MID TO EVEN UPPER 30S AS SUN EATS AWAY AT MEAGER
SNOW COVER.
THEN SUNDAY NIGHT...THERE IS A STRONG SIGNAL FOR GOOD RADIATIONAL
COOLING...ESPECIALLY ON THE ECMWF...WHICH MAY BE A BIT TOO
AGGRESSIVE WITH ITS ZERO TO SLIGHTLY BELOW ZERO NUMBERS FOR NORTH
CENTRAL IL. BASICALLY CONTINUED IDEA OF PREVIOUS FORECAST WITH
POTENTIAL FOR SINGLE DIGIT LOWS WEST OF FOX RIVER. ON SUNDAY...THE
COLD START MAY KEEP TEMPS IN CHECK SOMEWHAT...BUT MARCH SUN ANGLE
AND LONGER DAYLIGHT HOURS EXPECTED TO COMPENSATE...IN ADDITION TO
SLIGHTLY WARMER TEMPS ALOFT. MEDIAN ORD HIGHS FOR DAYS WITH 850
TEMPS AS PROGGED ON SUNDAY IN -6 TO -8 RANGE IS 38. DIDNT GO THIS
MILD DUE TO COLD START AND SNOW COVER OVER NORTHERN CWA...BUT
BUMPED UP TEMPS A FEW DEGREES FROM PREVIOUS. IF SNOW COVER CAN BE
ELIMINATED ON SATURDAY OVER SOUTH...WOULDNT BE SURPRISED IF SOME
LOCATIONS TAG 40 DEGREES...BUT FOR NOW WENT WITH UPPER 30S IN
CENTRAL IL. INCREASING CLOUD COVER SHOULD RESULT IN LOWS SEVERAL
DEGREES WARMER SUNDAY NIGHT THAN SATURDAY NIGHT.
LONG TERM...MONDAY THROUGH THURSDAY
MAIN FOCUS IS ON VERY ENERGETIC CLIPPER SYSTEM EARLY NEXT WEEK.
THERE HAVE BEEN FAIRLY SIGNIFICANT RUN TO RUN CHANGES WITH THE
TIMING AND TRACK OF THE STRONG UPPER LOW AND SURFACE REFLECTION.
WOULD EXPECT THIS TO CONTINUE UNTIL UPPER WAVE MAKES LANDFALL IN
PACIFIC NORTHWEST SATURDAY NIGHT ALLOWING FOR SAMPLING BY RAOB
NETWORK. AS IT STANDS RIGHT NOW...00Z GUIDANCE HAS SHIFTED BACK
NORTH...WHICH WOULD PUT MOST OF CWA IN LINE FOR A POTENTIALLY
ACCUMULATING SNOW. COULD SEE THE START OF SOME WAA SNOWS AHEAD OF
SYSTEM ON MONDAY...SO BLENDED POPS WERE MAINTAINED.
HOWEVER...BIGGEST CHANGE WAS TO GREATLY INCREASE POPS ABOVE
ALLBLEND MONDAY NIGHT AND TUESDAY IN LINE WITH A SLOWER
PROGRESSION OF THE UPPER LOW AND ATTENDANT SURFACE LOW FAVORED BY
THE 00Z ECMWF...CANADIAN...GEFS AND HPC. GFS APPEARS MUCH TOO FAST
IN CLEARING THE SYSTEM OFF TO THE EAST. FOR NOW...BUMPED UP POPS
TO MID RANGE CHANCE GIVEN UNCERTAINTY.
AS CURRENTLY MODELED...THE UPPER LOW WITH THIS SYSTEM LOOKS QUITE
STRONG...WITH A TIGHT BAROCLINIC ZONE ALONG/AHEAD OF ITS TRACK. THUS
THERE COULD BE A NICE SWATH OF SNOW PUT DOWN SOMEWHERE OVER/NEAR THE
REGION. ON THE NEGATIVE SIDE...TEMPERATURES AS IS USUALLY THE CASE
IN MARCH WOULD BE NEAR FREEZING...SO THE SNOW WOULD HAVE TO COME
DOWN HARD TO ACCUMULATE EFFICIENTLY. LOTS OF TIME TO MONITOR THIS
SYSTEM.
FOR THE REST OF THE EXTENDED AND BEYOND...AFTER A FAIRLY COOL DAY ON
WEDNESDAY BEHIND THE EARLY WEEK SYSTEM...THERE COULD BE BRIEF WARM UP
TO NORMAL TO ABOVE NORMAL AS THE PATTERN TRANSITIONS FROM AN EASTERN
TROUGH/WESTERN RIDGE (POSITIVE PNA) CONFIGURATION TO A WESTERN
TROUGH/EASTERN RIDGE (NEGATIVE PNA) PATTERN. WITH RIDGING FIRST
AMPLIFYING INTO CENTER OF CONUS...WE COULD SEE A FEW DAYS OF
TEMPERATURES AT LEAST BACK INTO THE 40S.
HOWEVER...THE LONG RANGE ENSEMBLES LOOKING BEYOND THIS 7 DAY
FORECAST PERIOD ARE HOLDING ONTO THE IDEA OF MAINTAINING HIGH
LATITUDE BLOCKING/NEGATIVE NAO AND NEGATIVE AO THROUGH MID MARCH.
IN ADDITION...RIDGING MAY AMPLIFY OVER OR NEAR ALASKA WHICH ALLOWS
FRESH COLD AIR TO INFILTRATE CANADA AND THE NORTHERN CONUS. BOTTOM
LINE IS ANY WARM UP COULD BE QUICKLY FOLLOWED BY A RETURN TO THE
COLDER THAN NORMAL PATTERN. NO MARCH 2012 PATTERN IS SEEN IN THE
EXTENDED FOR ANYONE HOPING FOR AN EARLY SUMMER AGAIN.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* WINDS BECOMING NORTH-NORTHEAST EARLY THIS AFTERNOON.
* MVFR CIGS.
* LAKE EFFECT SNOW SHOWERS POSSIBLE AGAIN TONIGHT...LOWER MVFR VIS
POSSIBLE.
KJB
//DISCUSSION...UPDATED 18Z...
THE LAKE EFFECT SNOW SHOWER ACTIVITY CONTINUES TO ABATE ACROSS THE
TERMINALS EARLY THIS AFTERNOON AS THE LOWER LEVEL CONVERGENCE WEAKENS
IN RESPONSE TO AN INVERTED SURFACE TROUGH MOVING ONSHORE ACROSS
NORTHEASTERN ILLINOIS. WINDS ARE BECOMING NORTH-NORTHEASTERLY IN
THE WAKE OF THIS SURFACE TROUGH...AND I EXPECT ALL OF THE EASTERN
TERMINALS TO BE 010-020 BY OR SHORTLY AFTER 18 UTC. ANY ADDITIONAL
SNOW SHOWER ACTIVITY THIS AFTERNOON LOOKS TO BE VERY LIGHT...WITH
MINIMAL IMPACTS TO THE VISIBILITY EXPECTED.
THE SURFACE FLOW WILL REMAIN OUT OF THE NORTH NORTHEAST INTO
SATURDAY AS A SURFACE RIDGE OF HIGH PRESSURE CONTINUES TO BUILD
EASTWARD ACROSS THE REGION. SOME ADDITIONAL LAKE EFFECT SNOW
SHOWER ACTIVITY IS POSSIBLY TONIGHT ACROSS THE EASTERN TERMINALS
AS THE LAKESHORE CONVERGENCE INCREASES IN RESPONSE TO A LAND BREEZE.
HOWEVER...THE OVERALL THERMODYNAMIC SETUP IS SLOWLY BECOMING
SLIGHTLY LESS FAVORABLE FOR LAKE EFFECT SNOW. THUS ONLY SOME MVFR
VIS IS CURRENTLY EXPECTED...WITH A SMALL POSSIBILITY OF A SHORT
PERIOD OF LOWER VIS NOT OUT OF THE QUESTION TONIGHT.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM TO HIGH CONFIDENCE ON NORTH-NORTHEAST WINDS THROUGH THIS AFTERNOON.
* LOW TO MEDIUM CONFIDENCE ON ADDITIONAL LAKE EFFECT SNOW SHOWERS TONIGHT.
KJB
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...MVFR CIGS POSSIBLE EARLY.
SUNDAY...VFR.
MONDAY...CHANCE OF LIGHT SNOW IN THE AFTERNOON. MVFR POSSIBLE
LATE.
MONDAY NIGHT INTO TUESDAY...GOOD CHANCE OF SNOW. IFR PROBABLE.
WEDNESDAY...MVFR CIGS POSSIBLE.
THURSDAY...VFR EXPECTED.
IZZI
&&
.MARINE...
222 AM CST
MODERATELY STRONG NORTH WINDS LIKELY TO CONTINUE THROUGH SATURDAY
WITH OCCASIONAL GALE FORCE GUSTS A POSSIBILITY...ESPECIALLY LATER
THIS AFTERNOON INTO THE EVENING...BUT GENERALLY THINK ANY GALES
WILL BE INFREQUENT ENOUGH TO KEEP OUT OF THE FORECAST. WINDS WILL
BEGIN TO DIMINISHING LATER SATURDAY INTO SUNDAY AS RIDGE AXIS
APPROACHES AND THEN MOVES ACROSS THE LAKE SUNDAY NIGHT. ANOTHER
SYSTEM WILL PASS TO THE SOUTHWEST OF THE LAKE EARLY/MIDDLE PART OF
NEXT WEEK WITH WINDS FRESHENING UP A BIT...BUT SYSTEM SHOULD BE
WEAK ENOUGH AND FAR ENOUGH AWAY TO NOT CAUSE ANY MAJOR
WINDS/WAVES.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 AM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 9 AM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
951 AM CST FRI MAR 1 2013
.DISCUSSION...
919 AM CST
UPDATED THE GRIDS FOR THIS MORNING...MAINLY TO ACCOUNT FOR ONGOING
LAKE EFFECT SNOW SHOWERS.
LATEST RADAR IMAGERY DEPICTING SOME LIGHT RETURNS ACROSS ALL OF
NORTHERN ILLINOIS WITH AN ISOLATED AREA OF FAIRLY DECENT
RETURNS...PRIMARILY ACROSS SOUTHEAST COOK COUNTY AND NORTHWEST
LAKE COUNTY IN INDIANA. UNDER THE LIGHTER RETURNS LIGHT SNOW
CONTINUES WITH VIS STAYING CONFINED TO ONLY THE 3-6 MILE
RANGE...WITH VIS LIKELY AT OR UNDER 1 MILE UNDER THE STRONGER
RETURNS. THESE SNOW SHOWERS ARE IN RESPONSE TO PERSISTENT
NORTH/NORTHEAST FLOW OFF OF A MODERATELY UNSTABLE LAKE...AS WELL
AS WEAK LARGE SCALE LIFT. LATEST SURFACE ANALYSIS INDICATING A
SURFACE TROUGH SITUATED ACROSS THE SOUTHERN HALF OF THE
LAKE...EXTENDING BACK NORTHWEST FROM A WEAK SURFACE LOW OVER
IN/KY. THIS HAS RESULTED IN AN AREA OF BETTER CONVERGENCE THIS
MORNING...WHICH HAS THEN PROVIDED THIS ISOLATED AREA OF STRONGER
SNOW SHOWERS. LATEST SHORT TERM GUIDANCE IS INDICATING THIS TROUGH
TO SLOWLY EXIT/DAMPEN WITH ALL SURFACE WINDS BECOMING MORE
NORTHERLY...AND LOSS OF BETTER CONVERGENCE. SO DO EXPECT THIS
ISOLATED AREA OF STRONGER SNOW SHOWERS TO PERSIST OVER THE NEXT
COUPLE OF HOURS...ONCE AGAIN PRIMARILY AFFECTING ONLY SOUTHEAST
COOK AND NORTHWEST LAKE COUNTY IN INDIANA. UNDER THESE STRONGER
RETURNS IT WOULD NOT BE OUT OF THE QUESTION FOR SOME ADDITIONAL
ACCUMULATIONS...WITH 1 TO 3 INCHES NOT OF THE REALM OF
POSSIBILITY THROUGH MID DAY. LIGHT SNOW SHOWERS ARE THEN EXPECTED
TO CONTINUE INTO THE AFTERNOON...BUT WITH ONLY LIGHT ACCUMULATIONS
ANTICIPATED.
RODRIGUEZ
//PREV DISCUSSION...
330 AM CST
FORECAST CONCERNS ARE LAKE EFFECT SNOW SHOWER POTENTIAL THE NEXT FEW
DAYS...COLD TEMPERATURES OVER THE WEEKEND...AND A POSSIBLE SNOW
PRODUCING SYSTEM EARLY NEXT WEEK.
SHORT TERM...TODAY THROUGH SUNDAY NIGHT...
SLIGHTLY COLDER AIR MASS WILL SETTLE OVER THE REGION TODAY ON
CONTINUED NORTHERLY FLOW...WITH A LARGE AREA OF HIGH PRESSURE
BUILDING IN FROM THE NORTH. THIS SHOULD KEEP HIGHS A FEW DEGREES
COOLER THAN YESTERDAY. LAKE EFFECT SET UP IS QUITE MARGINAL
THERMODYNAMICALLY...BUT COMPENSATING SOMEWHAT WILL BE GOOD
CONVERGENCE AND FETCH WITH NORTH-NORTHEAST LOW LEVEL FLOW. THE
CONVERGENCE AND EVEN SOME ENHANCED LIFT IS BEST ALIGNED OVER
ILLINOIS AND PORTION OF NW INDIANA LAKEFRONT THROUGH MID/LATE
MORNING...SO BUMPED UP POPS SOME FROM PREVIOUS FORECAST. COULD SEE
SOME VERY LIGHT ACCUMULATIONS. OUTSIDE OF LAKE EFFECT...THERE MAY BE
SOME FLURRIES INLAND. ALTHOUGH STRATUS CAN CLEAR OUT QUICKER THIS
TIME OF YEAR DUE TO HIGHER SUN ANGLE...THINK THE NAM IS BEING WAY
TOO AGGRESSIVE WITH CLEARING TREND FROM NORTH. USED RAP GUIDANCE FOR
NEAR TERM SKY FORECAST. MOST OF CWA SHOULD SEE OVC THROUGH DAYLIGHT
HOURS.
THE SAME GENERAL IDEA OF DECENT CONVERGENCE BUT VERY MARGINAL
THERMODYNAMICS AND INVERSION HEIGHTS CONTINUES THROUGH SATURDAY WITH
THE LAKE EFFECT. WILL CONTINUE TO CARRY CHANCE POPS...THOUGH THEY
WILL SLIDE INTO NW INDIANA ON SATURDAY AS NORTHERLY FLOW BECOMES
JUST WEST OF DUE NORTH. SKIES SHOULD START TO CLEAR BY DAYBREAK OVER
THE NW CWA...SO TEMPERATURES SHOULD DROP PRETTY WELL THERE GIVEN
THE GOOD RADIATION COOLING...PROBABLY INTO THE MID TEENS.
OUTSIDE OF LAKE EFFECT CONCERNS...THE ONLY FOCUS OVER THE WEEKEND
WAS TEMPERATURES WITH HIGH PRESSURE BUILDING OVERHEAD. FOR HIGHS
ON SATURDAY...SUSPECT THAT THE MARCH SUN WILL GO TO WORK ON THE
SNOW COVER...ESPECIALLY FOR AREAS THAT DIDNT SEE MUCH THIS WEEK.
FOR MARCH 1-15...WITH 850 TEMPS AROUND -10C AS IS PROGGED ON
SATURDAY...MEDIAN HIGH AT ORD IS 34 DEGREES. WENT JUST UNDER THAT
IN NORTHERN CWA/ESPECIALLY IN THE NORTHEAST WHERE SNOW PACK IS
DEEPEST...YIELDING HIGHS AROUND 30. TO THE SOUTH OF I-80...SUSPECT
WE`LL SEE SOME MID TO EVEN UPPER 30S AS SUN EATS AWAY AT MEAGER
SNOW COVER.
THEN SUNDAY NIGHT...THERE IS A STRONG SIGNAL FOR GOOD RADIATIONAL
COOLING...ESPECIALLY ON THE ECMWF...WHICH MAY BE A BIT TOO
AGGRESSIVE WITH ITS ZERO TO SLIGHTLY BELOW ZERO NUMBERS FOR NORTH
CENTRAL IL. BASICALLY CONTINUED IDEA OF PREVIOUS FORECAST WITH
POTENTIAL FOR SINGLE DIGIT LOWS WEST OF FOX RIVER. ON SUNDAY...THE
COLD START MAY KEEP TEMPS IN CHECK SOMEWHAT...BUT MARCH SUN ANGLE
AND LONGER DAYLIGHT HOURS EXPECTED TO COMPENSATE...IN ADDITION TO
SLIGHTLY WARMER TEMPS ALOFT. MEDIAN ORD HIGHS FOR DAYS WITH 850
TEMPS AS PROGGED ON SUNDAY IN -6 TO -8 RANGE IS 38. DIDNT GO THIS
MILD DUE TO COLD START AND SNOW COVER OVER NORTHERN CWA...BUT
BUMPED UP TEMPS A FEW DEGREES FROM PREVIOUS. IF SNOW COVER CAN BE
ELIMINATED ON SATURDAY OVER SOUTH...WOULDNT BE SURPRISED IF SOME
LOCATIONS TAG 40 DEGREES...BUT FOR NOW WENT WITH UPPER 30S IN
CENTRAL IL. INCREASING CLOUD COVER SHOULD RESULT IN LOWS SEVERAL
DEGREES WARMER SUNDAY NIGHT THAN SATURDAY NIGHT.
LONG TERM...MONDAY THROUGH THURSDAY
MAIN FOCUS IS ON VERY ENERGETIC CLIPPER SYSTEM EARLY NEXT WEEK.
THERE HAVE BEEN FAIRLY SIGNIFICANT RUN TO RUN CHANGES WITH THE
TIMING AND TRACK OF THE STRONG UPPER LOW AND SURFACE REFLECTION.
WOULD EXPECT THIS TO CONTINUE UNTIL UPPER WAVE MAKES LANDFALL IN
PACIFIC NORTHWEST SATURDAY NIGHT ALLOWING FOR SAMPLING BY RAOB
NETWORK. AS IT STANDS RIGHT NOW...00Z GUIDANCE HAS SHIFTED BACK
NORTH...WHICH WOULD PUT MOST OF CWA IN LINE FOR A POTENTIALLY
ACCUMULATING SNOW. COULD SEE THE START OF SOME WAA SNOWS AHEAD OF
SYSTEM ON MONDAY...SO BLENDED POPS WERE MAINTAINED.
HOWEVER...BIGGEST CHANGE WAS TO GREATLY INCREASE POPS ABOVE
ALLBLEND MONDAY NIGHT AND TUESDAY IN LINE WITH A SLOWER
PROGRESSION OF THE UPPER LOW AND ATTENDANT SURFACE LOW FAVORED BY
THE 00Z ECMWF...CANADIAN...GEFS AND HPC. GFS APPEARS MUCH TOO FAST
IN CLEARING THE SYSTEM OFF TO THE EAST. FOR NOW...BUMPED UP POPS
TO MID RANGE CHANCE GIVEN UNCERTAINTY.
AS CURRENTLY MODELED...THE UPPER LOW WITH THIS SYSTEM LOOKS QUITE
STRONG...WITH A TIGHT BAROCLINIC ZONE ALONG/AHEAD OF ITS TRACK. THUS
THERE COULD BE A NICE SWATH OF SNOW PUT DOWN SOMEWHERE OVER/NEAR THE
REGION. ON THE NEGATIVE SIDE...TEMPERATURES AS IS USUALLY THE CASE
IN MARCH WOULD BE NEAR FREEZING...SO THE SNOW WOULD HAVE TO COME
DOWN HARD TO ACCUMULATE EFFICIENTLY. LOTS OF TIME TO MONITOR THIS
SYSTEM.
FOR THE REST OF THE EXTENDED AND BEYOND...AFTER A FAIRLY COOL DAY ON
WEDNESDAY BEHIND THE EARLY WEEK SYSTEM...THERE COULD BE BRIEF WARM UP
TO NORMAL TO ABOVE NORMAL AS THE PATTERN TRANSITIONS FROM AN EASTERN
TROUGH/WESTERN RIDGE (POSITIVE PNA) CONFIGURATION TO A WESTERN
TROUGH/EASTERN RIDGE (NEGATIVE PNA) PATTERN. WITH RIDGING FIRST
AMPLIFYING INTO CENTER OF CONUS...WE COULD SEE A FEW DAYS OF
TEMPERATURES AT LEAST BACK INTO THE 40S.
HOWEVER...THE LONG RANGE ENSEMBLES LOOKING BEYOND THIS 7 DAY
FORECAST PERIOD ARE HOLDING ONTO THE IDEA OF MAINTAINING HIGH
LATITUDE BLOCKING/NEGATIVE NAO AND NEGATIVE AO THROUGH MID MARCH.
IN ADDITION...RIDGING MAY AMPLIFY OVER OR NEAR ALASKA WHICH ALLOWS
FRESH COLD AIR TO INFILTRATE CANADA AND THE NORTHERN CONUS. BOTTOM
LINE IS ANY WARM UP COULD BE QUICKLY FOLLOWED BY A RETURN TO THE
COLDER THAN NORMAL PATTERN. NO MARCH 2012 PATTERN IS SEEN IN THE
EXTENDED FOR ANYONE HOPING FOR AN EARLY SUMMER AGAIN.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* SCT LAKE EFFECT SHSN...VIS BRIEFLY DROPPING DOWN IN THE 2 TO 3
SM RANGE IN THE HEAVIER SHOWERS...ESPECIALLY THIS MORNING. SNOW
SHOWERS AND FLURRIES MAY CONTINUE THIS AFTERNOON BUT WILL BE LESS
ROBUST THAN THE CURRENT ACTIVITY.
* NNW WINDS TO TRANSITION TO N-NE BY EARLY AFTERNOON
KB
//DISCUSSION...UPDATED 12Z...
EXTENSIVE HIGH END MVFR/LOW END VFR STRATUS DECK BLANKETS THE
REGION WITH SOME POCKETS OF FLURRIES LIKELY TO TO PERSIST THRU
TODAY. LAKE EFFECT FLURRIES AND SCATTERED SNOW SHOWERS WILL
CONTINUE AT LEAST THROUGH THE EARLY AFTERNOON INTO CHGO AREA...AND
POSSIBLY INTO THIS EVENING. SMALL THREAT OF SOME BRIEF VSBY
REDUCTIONS IN -SHSN THIS MORNING...BUT PROBABLY NOT BELOW 3SM WITH
CIGS LIKELY TO BE GENERALLY AT OR ABOVE 1500FT. LAND BREEZE
INFLUENCE TO WIND DIRECTION SHOULD RESULT IN WINDS BEING WEST OF
DUE NORTH WINDS EARLY THIS MORNING AT CHGO AREA TERMINALS WITH
TRANSITION TO MORE NE WINDS EXPECTED LATER THIS MORNING.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE IN SHSN WITH BRIEF PERIODS OF 2 TO 3 SM VIS.
* HIGH CONFIDENCE IN WIND SHIFT TO N-NE...BUT LOW CONFIDENCE IN
EXACT TIMING
* MEDIUM/HIGH CONFIDENCE IN CIGS FORECAST THROUGH THE PERIOD
KB
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...MVFR CIGS POSSIBLE EARLY.
SUNDAY...VFR.
MONDAY...CHANCE OF LIGHT SNOW IN THE AFTERNOON. MVFR POSSIBLE
LATE.
MONDAY NIGHT INTO TUESDAY...GOOD CHANCE OF SNOW. IFR PROBABLE.
WEDNESDAY...MVFR CIGS POSSIBLE.
THURSDAY...VFR EXPECTED.
IZZI
&&
.MARINE...
222 AM CST
MODERATELY STRONG NORTH WINDS LIKELY TO CONTINUE THROUGH SATURDAY
WITH OCCASIONAL GALE FORCE GUSTS A POSSIBILITY...ESPECIALLY LATER
THIS AFTERNOON INTO THE EVENING...BUT GENERALLY THINK ANY GALES
WILL BE INFREQUENT ENOUGH TO KEEP OUT OF THE FORECAST. WINDS WILL
BEGIN TO DIMINISHING LATER SATURDAY INTO SUNDAY AS RIDGE AXIS
APPROACHES AND THEN MOVES ACROSS THE LAKE SUNDAY NIGHT. ANOTHER
SYSTEM WILL PASS TO THE SOUTHWEST OF THE LAKE EARLY/MIDDLE PART OF
NEXT WEEK WITH WINDS FRESHENING UP A BIT...BUT SYSTEM SHOULD BE
WEAK ENOUGH AND FAR ENOUGH AWAY TO NOT CAUSE ANY MAJOR
WINDS/WAVES.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 AM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 9 AM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
935 AM CST FRI MAR 1 2013
.DISCUSSION...
919 AM CST
UPDATED THE GRIDS FOR THIS MORNING...MAINLY TO ACCOUNT FOR ONGOING
LAKE EFFECT SNOW SHOWERS.
LATEST RADAR IMAGERY DEPICTING SOME LIGHT RETURNS ACROSS ALL OF
NORTHERN ILLINOIS WITH AN ISOLATED AREA OF FAIRLY DECENT
RETURNS...PRIMARILY ACROSS SOUTHEAST COOK COUNTY AND NORTHWEST
LAKE COUNTY IN INDIANA. UNDER THE LIGHTER RETURNS LIGHT SNOW
CONTINUES WITH VIS STAYING CONFINED TO ONLY THE 3-6 MILE
RANGE...WITH VIS LIKELY AT OR UNDER 1 MILE UNDER THE STRONGER
RETURNS. THESE SNOW SHOWERS ARE IN RESPONSE TO PERSISTENT
NORTH/NORTHEAST FLOW OFF OF A MODERATELY UNSTABLE LAKE...AS WELL
AS WEAK LARGE SCALE LIFT. LATEST SURFACE ANALYSIS INDICATING A
SURFACE TROUGH SITUATED ACROSS THE SOUTHERN HALF OF THE
LAKE...EXTENDING BACK NORTHWEST FROM A WEAK SURFACE LOW OVER
IN/KY. THIS HAS RESULTED IN AN AREA OF BETTER CONVERGENCE THIS
MORNING...WHICH HAS THEN PROVIDED THIS ISOLATED AREA OF STRONGER
SNOW SHOWERS. LATEST SHORT TERM GUIDANCE IS INDICATING THIS TROUGH
TO SLOWLY EXIT/DAMPEN WITH ALL SURFACE WINDS BECOMING MORE
NORTHERLY...AND LOSS OF BETTER CONVERGENCE. SO DO EXPECT THIS
ISOLATED AREA OF STRONGER SNOW SHOWERS TO PERSIST OVER THE NEXT
COUPLE OF HOURS...ONCE AGAIN PRIMARILY AFFECTING ONLY SOUTHEAST
COOK AND NORTHWEST LAKE COUNTY IN INDIANA. UNDER THESE STRONGER
RETURNS IT WOULD NOT BE OUT OF THE QUESTION FOR SOME ADDITIONAL
ACCUMULATIONS...WITH 1 TO 3 INCHES NOT OF THE REALM OF
POSSIBILITY THROUGH MID DAY. LIGHT SNOW SHOWERS ARE THEN EXPECTED
TO CONTINUE INTO THE AFTERNOON...BUT WITH ONLY LIGHT ACCUMULATIONS
ANTICIPATED.
RODRIGUEZ
&&
.PREV DISCUSSION...
330 AM CST
FORECAST CONCERNS ARE LAKE EFFECT SNOW SHOWER POTENTIAL THE NEXT FEW
DAYS...COLD TEMPERATURES OVER THE WEEKEND...AND A POSSIBLE SNOW
PRODUCING SYSTEM EARLY NEXT WEEK.
SHORT TERM...TODAY THROUGH SUNDAY NIGHT...
SLIGHTLY COLDER AIR MASS WILL SETTLE OVER THE REGION TODAY ON
CONTINUED NORTHERLY FLOW...WITH A LARGE AREA OF HIGH PRESSURE
BUILDING IN FROM THE NORTH. THIS SHOULD KEEP HIGHS A FEW DEGREES
COOLER THAN YESTERDAY. LAKE EFFECT SET UP IS QUITE MARGINAL
THERMODYNAMICALLY...BUT COMPENSATING SOMEWHAT WILL BE GOOD
CONVERGENCE AND FETCH WITH NORTH-NORTHEAST LOW LEVEL FLOW. THE
CONVERGENCE AND EVEN SOME ENHANCED LIFT IS BEST ALIGNED OVER
ILLINOIS AND PORTION OF NW INDIANA LAKEFRONT THROUGH MID/LATE
MORNING...SO BUMPED UP POPS SOME FROM PREVIOUS FORECAST. COULD SEE
SOME VERY LIGHT ACCUMULATIONS. OUTSIDE OF LAKE EFFECT...THERE MAY BE
SOME FLURRIES INLAND. ALTHOUGH STRATUS CAN CLEAR OUT QUICKER THIS
TIME OF YEAR DUE TO HIGHER SUN ANGLE...THINK THE NAM IS BEING WAY
TOO AGGRESSIVE WITH CLEARING TREND FROM NORTH. USED RAP GUIDANCE FOR
NEAR TERM SKY FORECAST. MOST OF CWA SHOULD SEE OVC THROUGH DAYLIGHT
HOURS.
THE SAME GENERAL IDEA OF DECENT CONVERGENCE BUT VERY MARGINAL
THERMODYNAMICS AND INVERSION HEIGHTS CONTINUES THROUGH SATURDAY WITH
THE LAKE EFFECT. WILL CONTINUE TO CARRY CHANCE POPS...THOUGH THEY
WILL SLIDE INTO NW INDIANA ON SATURDAY AS NORTHERLY FLOW BECOMES
JUST WEST OF DUE NORTH. SKIES SHOULD START TO CLEAR BY DAYBREAK OVER
THE NW CWA...SO TEMPERATURES SHOULD DROP PRETTY WELL THERE GIVEN
THE GOOD RADIATION COOLING...PROBABLY INTO THE MID TEENS.
OUTSIDE OF LAKE EFFECT CONCERNS...THE ONLY FOCUS OVER THE WEEKEND
WAS TEMPERATURES WITH HIGH PRESSURE BUILDING OVERHEAD. FOR HIGHS
ON SATURDAY...SUSPECT THAT THE MARCH SUN WILL GO TO WORK ON THE
SNOW COVER...ESPECIALLY FOR AREAS THAT DIDNT SEE MUCH THIS WEEK.
FOR MARCH 1-15...WITH 850 TEMPS AROUND -10C AS IS PROGGED ON
SATURDAY...MEDIAN HIGH AT ORD IS 34 DEGREES. WENT JUST UNDER THAT
IN NORTHERN CWA/ESPECIALLY IN THE NORTHEAST WHERE SNOW PACK IS
DEEPEST...YIELDING HIGHS AROUND 30. TO THE SOUTH OF I-80...SUSPECT
WE`LL SEE SOME MID TO EVEN UPPER 30S AS SUN EATS AWAY AT MEAGER
SNOW COVER.
THEN SUNDAY NIGHT...THERE IS A STRONG SIGNAL FOR GOOD RADIATIONAL
COOLING...ESPECIALLY ON THE ECMWF...WHICH MAY BE A BIT TOO
AGGRESSIVE WITH ITS ZERO TO SLIGHTLY BELOW ZERO NUMBERS FOR NORTH
CENTRAL IL. BASICALLY CONTINUED IDEA OF PREVIOUS FORECAST WITH
POTENTIAL FOR SINGLE DIGIT LOWS WEST OF FOX RIVER. ON SUNDAY...THE
COLD START MAY KEEP TEMPS IN CHECK SOMEWHAT...BUT MARCH SUN ANGLE
AND LONGER DAYLIGHT HOURS EXPECTED TO COMPENSATE...IN ADDITION TO
SLIGHTLY WARMER TEMPS ALOFT. MEDIAN ORD HIGHS FOR DAYS WITH 850
TEMPS AS PROGGED ON SUNDAY IN -6 TO -8 RANGE IS 38. DIDNT GO THIS
MILD DUE TO COLD START AND SNOW COVER OVER NORTHERN CWA...BUT
BUMPED UP TEMPS A FEW DEGREES FROM PREVIOUS. IF SNOW COVER CAN BE
ELIMINATED ON SATURDAY OVER SOUTH...WOULDNT BE SURPRISED IF SOME
LOCATIONS TAG 40 DEGREES...BUT FOR NOW WENT WITH UPPER 30S IN
CENTRAL IL. INCREASING CLOUD COVER SHOULD RESULT IN LOWS SEVERAL
DEGREES WARMER SUNDAY NIGHT THAN SATURDAY NIGHT.
LONG TERM...MONDAY THROUGH THURSDAY
MAIN FOCUS IS ON VERY ENERGETIC CLIPPER SYSTEM EARLY NEXT WEEK.
THERE HAVE BEEN FAIRLY SIGNIFICANT RUN TO RUN CHANGES WITH THE
TIMING AND TRACK OF THE STRONG UPPER LOW AND SURFACE REFLECTION.
WOULD EXPECT THIS TO CONTINUE UNTIL UPPER WAVE MAKES LANDFALL IN
PACIFIC NORTHWEST SATURDAY NIGHT ALLOWING FOR SAMPLING BY RAOB
NETWORK. AS IT STANDS RIGHT NOW...00Z GUIDANCE HAS SHIFTED BACK
NORTH...WHICH WOULD PUT MOST OF CWA IN LINE FOR A POTENTIALLY
ACCUMULATING SNOW. COULD SEE THE START OF SOME WAA SNOWS AHEAD OF
SYSTEM ON MONDAY...SO BLENDED POPS WERE MAINTAINED.
HOWEVER...BIGGEST CHANGE WAS TO GREATLY INCREASE POPS ABOVE
ALLBLEND MONDAY NIGHT AND TUESDAY IN LINE WITH A SLOWER
PROGRESSION OF THE UPPER LOW AND ATTENDANT SURFACE LOW FAVORED BY
THE 00Z ECMWF...CANADIAN...GEFS AND HPC. GFS APPEARS MUCH TOO FAST
IN CLEARING THE SYSTEM OFF TO THE EAST. FOR NOW...BUMPED UP POPS
TO MID RANGE CHANCE GIVEN UNCERTAINTY.
AS CURRENTLY MODELED...THE UPPER LOW WITH THIS SYSTEM LOOKS QUITE
STRONG...WITH A TIGHT BAROCLINIC ZONE ALONG/AHEAD OF ITS TRACK. THUS
THERE COULD BE A NICE SWATH OF SNOW PUT DOWN SOMEWHERE OVER/NEAR THE
REGION. ON THE NEGATIVE SIDE...TEMPERATURES AS IS USUALLY THE CASE
IN MARCH WOULD BE NEAR FREEZING...SO THE SNOW WOULD HAVE TO COME
DOWN HARD TO ACCUMULATE EFFICIENTLY. LOTS OF TIME TO MONITOR THIS
SYSTEM.
FOR THE REST OF THE EXTENDED AND BEYOND...AFTER A FAIRLY COOL DAY ON
WEDNESDAY BEHIND THE EARLY WEEK SYSTEM...THERE COULD BE BRIEF WARM UP
TO NORMAL TO ABOVE NORMAL AS THE PATTERN TRANSITIONS FROM AN EASTERN
TROUGH/WESTERN RIDGE (POSITIVE PNA) CONFIGURATION TO A WESTERN
TROUGH/EASTERN RIDGE (NEGATIVE PNA) PATTERN. WITH RIDGING FIRST
AMPLIFYING INTO CENTER OF CONUS...WE COULD SEE A FEW DAYS OF
TEMPERATURES AT LEAST BACK INTO THE 40S.
HOWEVER...THE LONG RANGE ENSEMBLES LOOKING BEYOND THIS 7 DAY
FORECAST PERIOD ARE HOLDING ONTO THE IDEA OF MAINTAINING HIGH
LATITUDE BLOCKING/NEGATIVE NAO AND NEGATIVE AO THROUGH MID MARCH.
IN ADDITION...RIDGING MAY AMPLIFY OVER OR NEAR ALASKA WHICH ALLOWS
FRESH COLD AIR TO INFILTRATE CANADA AND THE NORTHERN CONUS. BOTTOM
LINE IS ANY WARM UP COULD BE QUICKLY FOLLOWED BY A RETURN TO THE
COLDER THAN NORMAL PATTERN. NO MARCH 2012 PATTERN IS SEEN IN THE
EXTENDED FOR ANYONE HOPING FOR AN EARLY SUMMER AGAIN.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* FLURRIES WITH SCT LAKE EFFECT SHSN...VIS BRIEFLY DROPPING DOWN IN
THE 2 TO 3 SM RANGE IN THE HEAVIER SHOWERS...ESPECIALLY THIS
MORNING.
* NNW WINDS TO TRANSITION TO N-NE BY LATE MORNING/EARLY AFTERNOON
IZZI/KB
//DISCUSSION...UPDATED 12Z...
EXTENSIVE HIGH END MVFR/LOW END VFR STRATUS DECK BLANKETS THE
REGION WITH SOME POCKETS OF FLURRIES LIKELY TO TO PERSIST THRU
TODAY. LAKE EFFECT FLURRIES AND SCATTERED SNOW SHOWERS WILL
CONTINUE AT LEAST THROUGH THE EARLY AFTERNOON INTO CHGO AREA...AND
POSSIBLY INTO THIS EVENING. SMALL THREAT OF SOME BRIEF VSBY
REDUCTIONS IN -SHSN THIS MORNING...BUT PROBABLY NOT BELOW 3SM WITH
CIGS LIKELY TO BE GENERALLY AT OR ABOVE 1500FT. LAND BREEZE
INFLUENCE TO WIND DIRECTION SHOULD RESULT IN WINDS BEING WEST OF
DUE NORTH WINDS EARLY THIS MORNING AT CHGO AREA TERMINALS WITH
TRANSITION TO MORE NE WINDS EXPECTED LATER THIS MORNING.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN SHSN WITH BRIEF PERIODS OF 2 TO 3 SM VIS.
* HIGH CONFIDENCE IN WIND SHIFT TO N-NE...BUT LOW CONFIDENCE IN
EXACT TIMING
* MEDIUM/HIGH CONFIDENCE IN CIGS FORECAST THROUGH THE PERIOD
IZZI/KB
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...MVFR CIGS POSSIBLE EARLY.
SUNDAY...VFR.
MONDAY...CHANCE OF LIGHT SNOW IN THE AFTERNOON. MVFR POSSIBLE
LATE.
MONDAY NIGHT INTO TUESDAY...GOOD CHANCE OF SNOW. IFR PROBABLE.
WEDNESDAY...MVFR CIGS POSSIBLE.
THURSDAY...VFR EXPECTED.
IZZI
&&
.MARINE...
222 AM CST
MODERATELY STRONG NORTH WINDS LIKELY TO CONTINUE THROUGH SATURDAY
WITH OCCASIONAL GALE FORCE GUSTS A POSSIBILITY...ESPECIALLY LATER
THIS AFTERNOON INTO THE EVENING...BUT GENERALLY THINK ANY GALES
WILL BE INFREQUENT ENOUGH TO KEEP OUT OF THE FORECAST. WINDS WILL
BEGIN TO DIMINISHING LATER SATURDAY INTO SUNDAY AS RIDGE AXIS
APPROACHES AND THEN MOVES ACROSS THE LAKE SUNDAY NIGHT. ANOTHER
SYSTEM WILL PASS TO THE SOUTHWEST OF THE LAKE EARLY/MIDDLE PART OF
NEXT WEEK WITH WINDS FRESHENING UP A BIT...BUT SYSTEM SHOULD BE
WEAK ENOUGH AND FAR ENOUGH AWAY TO NOT CAUSE ANY MAJOR
WINDS/WAVES.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 AM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 9 AM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
810 AM CST FRI MAR 1 2013
.DISCUSSION...
330 AM CST
FORECAST CONCERNS ARE LAKE EFFECT SNOW SHOWER POTENTIAL THE NEXT FEW
DAYS...COLD TEMPERATURES OVER THE WEEKEND...AND A POSSIBLE SNOW
PRODUCING SYSTEM EARLY NEXT WEEK.
SHORT TERM...TODAY THROUGH SUNDAY NIGHT...
SLIGHTLY COLDER AIR MASS WILL SETTLE OVER THE REGION TODAY ON
CONTINUED NORTHERLY FLOW...WITH A LARGE AREA OF HIGH PRESSURE
BUILDING IN FROM THE NORTH. THIS SHOULD KEEP HIGHS A FEW DEGREES
COOLER THAN YESTERDAY. LAKE EFFECT SET UP IS QUITE MARGINAL
THERMODYNAMICALLY...BUT COMPENSATING SOMEWHAT WILL BE GOOD
CONVERGENCE AND FETCH WITH NORTH-NORTHEAST LOW LEVEL FLOW. THE
CONVERGENCE AND EVEN SOME ENHANCED LIFT IS BEST ALIGNED OVER
ILLINOIS AND PORTION OF NW INDIANA LAKEFRONT THROUGH MID/LATE
MORNING...SO BUMPED UP POPS SOME FROM PREVIOUS FORECAST. COULD SEE
SOME VERY LIGHT ACCUMULATIONS. OUTSIDE OF LAKE EFFECT...THERE MAY BE
SOME FLURRIES INLAND. ALTHOUGH STRATUS CAN CLEAR OUT QUICKER THIS
TIME OF YEAR DUE TO HIGHER SUN ANGLE...THINK THE NAM IS BEING WAY
TOO AGGRESSIVE WITH CLEARING TREND FROM NORTH. USED RAP GUIDANCE FOR
NEAR TERM SKY FORECAST. MOST OF CWA SHOULD SEE OVC THROUGH DAYLIGHT
HOURS.
THE SAME GENERAL IDEA OF DECENT CONVERGENCE BUT VERY MARGINAL
THERMODYNAMICS AND INVERSION HEIGHTS CONTINUES THROUGH SATURDAY WITH
THE LAKE EFFECT. WILL CONTINUE TO CARRY CHANCE POPS...THOUGH THEY
WILL SLIDE INTO NW INDIANA ON SATURDAY AS NORTHERLY FLOW BECOMES
JUST WEST OF DUE NORTH. SKIES SHOULD START TO CLEAR BY DAYBREAK OVER
THE NW CWA...SO TEMPERATURES SHOULD DROP PRETTY WELL THERE GIVEN
THE GOOD RADIATION COOLING...PROBABLY INTO THE MID TEENS.
OUTSIDE OF LAKE EFFECT CONCERNS...THE ONLY FOCUS OVER THE WEEKEND
WAS TEMPERATURES WITH HIGH PRESSURE BUILDING OVERHEAD. FOR HIGHS
ON SATURDAY...SUSPECT THAT THE MARCH SUN WILL GO TO WORK ON THE
SNOW COVER...ESPECIALLY FOR AREAS THAT DIDNT SEE MUCH THIS WEEK.
FOR MARCH 1-15...WITH 850 TEMPS AROUND -10C AS IS PROGGED ON
SATURDAY...MEDIAN HIGH AT ORD IS 34 DEGREES. WENT JUST UNDER THAT
IN NORTHERN CWA/ESPECIALLY IN THE NORTHEAST WHERE SNOW PACK IS
DEEPEST...YIELDING HIGHS AROUND 30. TO THE SOUTH OF I-80...SUSPECT
WE`LL SEE SOME MID TO EVEN UPPER 30S AS SUN EATS AWAY AT MEAGER
SNOW COVER.
THEN SUNDAY NIGHT...THERE IS A STRONG SIGNAL FOR GOOD RADIATIONAL
COOLING...ESPECIALLY ON THE ECMWF...WHICH MAY BE A BIT TOO
AGGRESSIVE WITH ITS ZERO TO SLIGHTLY BELOW ZERO NUMBERS FOR NORTH
CENTRAL IL. BASICALLY CONTINUED IDEA OF PREVIOUS FORECAST WITH
POTENTIAL FOR SINGLE DIGIT LOWS WEST OF FOX RIVER. ON SUNDAY...THE
COLD START MAY KEEP TEMPS IN CHECK SOMEWHAT...BUT MARCH SUN ANGLE
AND LONGER DAYLIGHT HOURS EXPECTED TO COMPENSATE...IN ADDITION TO
SLIGHTLY WARMER TEMPS ALOFT. MEDIAN ORD HIGHS FOR DAYS WITH 850
TEMPS AS PROGGED ON SUNDAY IN -6 TO -8 RANGE IS 38. DIDNT GO THIS
MILD DUE TO COLD START AND SNOW COVER OVER NORTHERN CWA...BUT
BUMPED UP TEMPS A FEW DEGREES FROM PREVIOUS. IF SNOW COVER CAN BE
ELIMINATED ON SATURDAY OVER SOUTH...WOULDNT BE SURPRISED IF SOME
LOCATIONS TAG 40 DEGREES...BUT FOR NOW WENT WITH UPPER 30S IN
CENTRAL IL. INCREASING CLOUD COVER SHOULD RESULT IN LOWS SEVERAL
DEGREES WARMER SUNDAY NIGHT THAN SATURDAY NIGHT.
LONG TERM...MONDAY THROUGH THURSDAY
MAIN FOCUS IS ON VERY ENERGETIC CLIPPER SYSTEM EARLY NEXT WEEK.
THERE HAVE BEEN FAIRLY SIGNIFICANT RUN TO RUN CHANGES WITH THE
TIMING AND TRACK OF THE STRONG UPPER LOW AND SURFACE REFLECTION.
WOULD EXPECT THIS TO CONTINUE UNTIL UPPER WAVE MAKES LANDFALL IN
PACIFIC NORTHWEST SATURDAY NIGHT ALLOWING FOR SAMPLING BY RAOB
NETWORK. AS IT STANDS RIGHT NOW...00Z GUIDANCE HAS SHIFTED BACK
NORTH...WHICH WOULD PUT MOST OF CWA IN LINE FOR A POTENTIALLY
ACCUMULATING SNOW. COULD SEE THE START OF SOME WAA SNOWS AHEAD OF
SYSTEM ON MONDAY...SO BLENDED POPS WERE MAINTAINED.
HOWEVER...BIGGEST CHANGE WAS TO GREATLY INCREASE POPS ABOVE
ALLBLEND MONDAY NIGHT AND TUESDAY IN LINE WITH A SLOWER
PROGRESSION OF THE UPPER LOW AND ATTENDANT SURFACE LOW FAVORED BY
THE 00Z ECMWF...CANADIAN...GEFS AND HPC. GFS APPEARS MUCH TOO FAST
IN CLEARING THE SYSTEM OFF TO THE EAST. FOR NOW...BUMPED UP POPS
TO MID RANGE CHANCE GIVEN UNCERTAINTY.
AS CURRENTLY MODELED...THE UPPER LOW WITH THIS SYSTEM LOOKS QUITE
STRONG...WITH A TIGHT BAROCLINIC ZONE ALONG/AHEAD OF ITS TRACK. THUS
THERE COULD BE A NICE SWATH OF SNOW PUT DOWN SOMEWHERE OVER/NEAR THE
REGION. ON THE NEGATIVE SIDE...TEMPERATURES AS IS USUALLY THE CASE
IN MARCH WOULD BE NEAR FREEZING...SO THE SNOW WOULD HAVE TO COME
DOWN HARD TO ACCUMULATE EFFICIENTLY. LOTS OF TIME TO MONITOR THIS
SYSTEM.
FOR THE REST OF THE EXTENDED AND BEYOND...AFTER A FAIRLY COOL DAY ON
WEDNESDAY BEHIND THE EARLY WEEK SYSTEM...THERE COULD BE BRIEF WARM UP
TO NORMAL TO ABOVE NORMAL AS THE PATTERN TRANSITIONS FROM AN EASTERN
TROUGH/WESTERN RIDGE (POSITIVE PNA) CONFIGURATION TO A WESTERN
TROUGH/EASTERN RIDGE (NEGATIVE PNA) PATTERN. WITH RIDGING FIRST
AMPLIFYING INTO CENTER OF CONUS...WE COULD SEE A FEW DAYS OF
TEMPERATURES AT LEAST BACK INTO THE 40S.
HOWEVER...THE LONG RANGE ENSEMBLES LOOKING BEYOND THIS 7 DAY
FORECAST PERIOD ARE HOLDING ONTO THE IDEA OF MAINTAINING HIGH
LATITUDE BLOCKING/NEGATIVE NAO AND NEGATIVE AO THROUGH MID MARCH.
IN ADDITION...RIDGING MAY AMPLIFY OVER OR NEAR ALASKA WHICH ALLOWS
FRESH COLD AIR TO INFILTRATE CANADA AND THE NORTHERN CONUS. BOTTOM
LINE IS ANY WARM UP COULD BE QUICKLY FOLLOWED BY A RETURN TO THE
COLDER THAN NORMAL PATTERN. NO MARCH 2012 PATTERN IS SEEN IN THE
EXTENDED FOR ANYONE HOPING FOR AN EARLY SUMMER AGAIN.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* FLURRIES WITH SCT LAKE EFFECT SHSN...VIS BRIEFLY DROPPING DOWN IN
THE 2 TO 3 SM RANGE IN THE HEAVIER SHOWERS...ESPECIALLY THIS
MORNING.
* NNW WINDS TO TRANSITION TO N-NE BY LATE MORNING/EARLY AFTERNOON
IZZI/KB
//DISCUSSION...UPDATED 12Z...
EXTENSIVE HIGH END MVFR/LOW END VFR STRATUS DECK BLANKETS THE
REGION WITH SOME POCKETS OF FLURRIES LIKELY TO TO PERSIST THRU
TODAY. LAKE EFFECT FLURRIES AND SCATTERED SNOW SHOWERS WILL
CONTINUE AT LEAST THROUGH THE EARLY AFTERNOON INTO CHGO AREA...AND
POSSIBLY INTO THIS EVENING. SMALL THREAT OF SOME BRIEF VSBY
REDUCTIONS IN -SHSN THIS MORNING...BUT PROBABLY NOT BELOW 3SM WITH
CIGS LIKELY TO BE GENERALLY AT OR ABOVE 1500FT. LAND BREEZE
INFLUENCE TO WIND DIRECTION SHOULD RESULT IN WINDS BEING WEST OF
DUE NORTH WINDS EARLY THIS MORNING AT CHGO AREA TERMINALS WITH
TRANSITION TO MORE NE WINDS EXPECTED LATER THIS MORNING.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN SHSN WITH BRIEF PERIODS OF 2 TO 3 SM VIS.
* HIGH CONFIDENCE IN WIND SHIFT TO N-NE...BUT LOW CONFIDENCE IN
EXACT TIMING
* MEDIUM/HIGH CONFIDENCE IN CIGS FORECAST THROUGH THE PERIOD
IZZI/KB
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...MVFR CIGS POSSIBLE EARLY.
SUNDAY...VFR.
MONDAY...CHANCE OF LIGHT SNOW IN THE AFTERNOON. MVFR POSSIBLE
LATE.
MONDAY NIGHT INTO TUESDAY...GOOD CHANCE OF SNOW. IFR PROBABLE.
WEDNESDAY...MVFR CIGS POSSIBLE.
THURSDAY...VFR EXPECTED.
IZZI
&&
.MARINE...
222 AM CST
MODERATELY STRONG NORTH WINDS LIKELY TO CONTINUE THROUGH SATURDAY
WITH OCCASIONAL GALE FORCE GUSTS A POSSIBILITY...ESPECIALLY LATER
THIS AFTERNOON INTO THE EVENING...BUT GENERALLY THINK ANY GALES
WILL BE INFREQUENT ENOUGH TO KEEP OUT OF THE FORECAST. WINDS WILL
BEGIN TO DIMINISHING LATER SATURDAY INTO SUNDAY AS RIDGE AXIS
APPROACHES AND THEN MOVES ACROSS THE LAKE SUNDAY NIGHT. ANOTHER
SYSTEM WILL PASS TO THE SOUTHWEST OF THE LAKE EARLY/MIDDLE PART OF
NEXT WEEK WITH WINDS FRESHENING UP A BIT...BUT SYSTEM SHOULD BE
WEAK ENOUGH AND FAR ENOUGH AWAY TO NOT CAUSE ANY MAJOR
WINDS/WAVES.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 AM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 9 AM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
507 AM CST FRI MAR 1 2013
.DISCUSSION...
330 AM CST
FORECAST CONCERNS ARE LAKE EFFECT SNOW SHOWER POTENTIAL THE NEXT FEW
DAYS...COLD TEMPERATURES OVER THE WEEKEND...AND A POSSIBLE SNOW
PRODUCING SYSTEM EARLY NEXT WEEK.
SHORT TERM...TODAY THROUGH SUNDAY NIGHT...
SLIGHTLY COLDER AIR MASS WILL SETTLE OVER THE REGION TODAY ON
CONTINUED NORTHERLY FLOW...WITH A LARGE AREA OF HIGH PRESSURE
BUILDING IN FROM THE NORTH. THIS SHOULD KEEP HIGHS A FEW DEGREES
COOLER THAN YESTERDAY. LAKE EFFECT SET UP IS QUITE MARGINAL
THERMODYNAMICALLY...BUT COMPENSATING SOMEWHAT WILL BE GOOD
CONVERGENCE AND FETCH WITH NORTH-NORTHEAST LOW LEVEL FLOW. THE
CONVERGENCE AND EVEN SOME ENHANCED LIFT IS BEST ALIGNED OVER
ILLINOIS AND PORTION OF NW INDIANA LAKEFRONT THROUGH MID/LATE
MORNING...SO BUMPED UP POPS SOME FROM PREVIOUS FORECAST. COULD SEE
SOME VERY LIGHT ACCUMULATIONS. OUTSIDE OF LAKE EFFECT...THERE MAY BE
SOME FLURRIES INLAND. ALTHOUGH STRATUS CAN CLEAR OUT QUICKER THIS
TIME OF YEAR DUE TO HIGHER SUN ANGLE...THINK THE NAM IS BEING WAY
TOO AGGRESSIVE WITH CLEARING TREND FROM NORTH. USED RAP GUIDANCE FOR
NEAR TERM SKY FORECAST. MOST OF CWA SHOULD SEE OVC THROUGH DAYLIGHT
HOURS.
THE SAME GENERAL IDEA OF DECENT CONVERGENCE BUT VERY MARGINAL
THERMODYNAMICS AND INVERSION HEIGHTS CONTINUES THROUGH SATURDAY WITH
THE LAKE EFFECT. WILL CONTINUE TO CARRY CHANCE POPS...THOUGH THEY
WILL SLIDE INTO NW INDIANA ON SATURDAY AS NORTHERLY FLOW BECOMES
JUST WEST OF DUE NORTH. SKIES SHOULD START TO CLEAR BY DAYBREAK OVER
THE NW CWA...SO TEMPERATURES SHOULD DROP PRETTY WELL THERE GIVEN
THE GOOD RADIATION COOLING...PROBABLY INTO THE MID TEENS.
OUTSIDE OF LAKE EFFECT CONCERNS...THE ONLY FOCUS OVER THE WEEKEND
WAS TEMPERATURES WITH HIGH PRESSURE BUILDING OVERHEAD. FOR HIGHS
ON SATURDAY...SUSPECT THAT THE MARCH SUN WILL GO TO WORK ON THE
SNOW COVER...ESPECIALLY FOR AREAS THAT DIDNT SEE MUCH THIS WEEK.
FOR MARCH 1-15...WITH 850 TEMPS AROUND -10C AS IS PROGGED ON
SATURDAY...MEDIAN HIGH AT ORD IS 34 DEGREES. WENT JUST UNDER THAT
IN NORTHERN CWA/ESPECIALLY IN THE NORTHEAST WHERE SNOW PACK IS
DEEPEST...YIELDING HIGHS AROUND 30. TO THE SOUTH OF I-80...SUSPECT
WE`LL SEE SOME MID TO EVEN UPPER 30S AS SUN EATS AWAY AT MEAGER
SNOW COVER.
THEN SUNDAY NIGHT...THERE IS A STRONG SIGNAL FOR GOOD RADIATIONAL
COOLING...ESPECIALLY ON THE ECMWF...WHICH MAY BE A BIT TOO
AGGRESSIVE WITH ITS ZERO TO SLIGHTLY BELOW ZERO NUMBERS FOR NORTH
CENTRAL IL. BASICALLY CONTINUED IDEA OF PREVIOUS FORECAST WITH
POTENTIAL FOR SINGLE DIGIT LOWS WEST OF FOX RIVER. ON SUNDAY...THE
COLD START MAY KEEP TEMPS IN CHECK SOMEWHAT...BUT MARCH SUN ANGLE
AND LONGER DAYLIGHT HOURS EXPECTED TO COMPENSATE...IN ADDITION TO
SLIGHTLY WARMER TEMPS ALOFT. MEDIAN ORD HIGHS FOR DAYS WITH 850
TEMPS AS PROGGED ON SUNDAY IN -6 TO -8 RANGE IS 38. DIDNT GO THIS
MILD DUE TO COLD START AND SNOW COVER OVER NORTHERN CWA...BUT
BUMPED UP TEMPS A FEW DEGREES FROM PREVIOUS. IF SNOW COVER CAN BE
ELIMINATED ON SATURDAY OVER SOUTH...WOULDNT BE SURPRISED IF SOME
LOCATIONS TAG 40 DEGREES...BUT FOR NOW WENT WITH UPPER 30S IN
CENTRAL IL. INCREASING CLOUD COVER SHOULD RESULT IN LOWS SEVERAL
DEGREES WARMER SUNDAY NIGHT THAN SATURDAY NIGHT.
LONG TERM...MONDAY THROUGH THURSDAY
MAIN FOCUS IS ON VERY ENERGETIC CLIPPER SYSTEM EARLY NEXT WEEK.
THERE HAVE BEEN FAIRLY SIGNIFICANT RUN TO RUN CHANGES WITH THE
TIMING AND TRACK OF THE STRONG UPPER LOW AND SURFACE REFLECTION.
WOULD EXPECT THIS TO CONTINUE UNTIL UPPER WAVE MAKES LANDFALL IN
PACIFIC NORTHWEST SATURDAY NIGHT ALLOWING FOR SAMPLING BY RAOB
NETWORK. AS IT STANDS RIGHT NOW...00Z GUIDANCE HAS SHIFTED BACK
NORTH...WHICH WOULD PUT MOST OF CWA IN LINE FOR A POTENTIALLY
ACCUMULATING SNOW. COULD SEE THE START OF SOME WAA SNOWS AHEAD OF
SYSTEM ON MONDAY...SO BLENDED POPS WERE MAINTAINED.
HOWEVER...BIGGEST CHANGE WAS TO GREATLY INCREASE POPS ABOVE
ALLBLEND MONDAY NIGHT AND TUESDAY IN LINE WITH A SLOWER
PROGRESSION OF THE UPPER LOW AND ATTENDANT SURFACE LOW FAVORED BY
THE 00Z ECMWF...CANADIAN...GEFS AND HPC. GFS APPEARS MUCH TOO FAST
IN CLEARING THE SYSTEM OFF TO THE EAST. FOR NOW...BUMPED UP POPS
TO MID RANGE CHANCE GIVEN UNCERTAINTY.
AS CURRENTLY MODELED...THE UPPER LOW WITH THIS SYSTEM LOOKS QUITE
STRONG...WITH A TIGHT BAROCLINIC ZONE ALONG/AHEAD OF ITS TRACK. THUS
THERE COULD BE A NICE SWATH OF SNOW PUT DOWN SOMEWHERE OVER/NEAR THE
REGION. ON THE NEGATIVE SIDE...TEMPERATURES AS IS USUALLY THE CASE
IN MARCH WOULD BE NEAR FREEZING...SO THE SNOW WOULD HAVE TO COME
DOWN HARD TO ACCUMULATE EFFICIENTLY. LOTS OF TIME TO MONITOR THIS
SYSTEM.
FOR THE REST OF THE EXTENDED AND BEYOND...AFTER A FAIRLY COOL DAY ON
WEDNESDAY BEHIND THE EARLY WEEK SYSTEM...THERE COULD BE BRIEF WARM UP
TO NORMAL TO ABOVE NORMAL AS THE PATTERN TRANSITIONS FROM AN EASTERN
TROUGH/WESTERN RIDGE (POSITIVE PNA) CONFIGURATION TO A WESTERN
TROUGH/EASTERN RIDGE (NEGATIVE PNA) PATTERN. WITH RIDGING FIRST
AMPLIFYING INTO CENTER OF CONUS...WE COULD SEE A FEW DAYS OF
TEMPERATURES AT LEAST BACK INTO THE 40S.
HOWEVER...THE LONG RANGE ENSEMBLES LOOKING BEYOND THIS 7 DAY
FORECAST PERIOD ARE HOLDING ONTO THE IDEA OF MAINTAINING HIGH
LATITUDE BLOCKING/NEGATIVE NAO AND NEGATIVE AO THROUGH MID MARCH.
IN ADDITION...RIDGING MAY AMPLIFY OVER OR NEAR ALASKA WHICH ALLOWS
FRESH COLD AIR TO INFILTRATE CANADA AND THE NORTHERN CONUS. BOTTOM
LINE IS ANY WARM UP COULD BE QUICKLY FOLLOWED BY A RETURN TO THE
COLDER THAN NORMAL PATTERN. NO MARCH 2012 PATTERN IS SEEN IN THE
EXTENDED FOR ANYONE HOPING FOR AN EARLY SUMMER AGAIN.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* FLURRIES AND POSSIBLY SCT -SHSN...ESPECIALLY THRU EARLY FRI
AFTERNOON
* NNW WINDS TO TRANSITION TO NE FRIDAY MORNING
IZZI
//DISCUSSION...UPDATED 12Z...
EXTENSIVE HIGH END MVFR/LOW END VFR STRATUS DECK BLANKETS THE
REGION WITH SOME POCKETS OF FLURRIES LIKELY TO TO PERSIST THRU
TODAY. LAKE EFFECT FLURRIES AND SCATTERED SNOW SHOWERS WILL
CONTINUE AT LEAST THROUGH THE EARLY AFTERNOON INTO CHGO AREA...AND
POSSIBLY INTO THIS EVENING. SMALL THREAT OF SOME BRIEF VSBY
REDUCTIONS IN -SHSN THIS MORNING...BUT PROBABLY NOT BELOW 3SM WITH
CIGS LIKELY TO BE GENERALLY AT OR ABOVE 1500FT. LAND BREEZE
INFLUENCE TO WIND DIRECTION SHOULD RESULT IN WINDS BEING WEST OF
DUE NORTH WINDS EARLY THIS MORNING AT CHGO AREA TERMINALS WITH
TRANSITION TO MORE NE WINDS EXPECTED LATER THIS MORNING.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* LOW/MEDIUM CONFIDENCE IN -SHSN POTENTIAL
* HIGH CONFIDENCE IN WIND SHIFT TO NE...BUT LOW CONFIDENCE IN
TIMING
* MEDIUM/HIGH CONFIDENCE IN CIGS FORECAST THROUGH THE PERIOD
IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...MVFR CIGS POSSIBLE EARLY.
SUNDAY...VFR.
MONDAY...CHANCE OF LIGHT SNOW IN THE AFTERNOON. MVFR POSSIBLE
LATE.
MONDAY NIGHT INTO TUESDAY...GOOD CHANCE OF SNOW. IFR PROBABLE.
WEDNESDAY...MVFR CIGS POSSIBLE.
THURSDAY...VFR EXPECTED.
IZZI
&&
.MARINE...
222 AM CST
MODERATELY STRONG NORTH WINDS LIKELY TO CONTINUE THROUGH SATURDAY
WITH OCCASIONAL GALE FORCE GUSTS A POSSIBILITY...ESPECIALLY LATER
THIS AFTERNOON INTO THE EVENING...BUT GENERALLY THINK ANY GALES
WILL BE INFREQUENT ENOUGH TO KEEP OUT OF THE FORECAST. WINDS WILL
BEGIN TO DIMINISHING LATER SATURDAY INTO SUNDAY AS RIDGE AXIS
APPROACHES AND THEN MOVES ACROSS THE LAKE SUNDAY NIGHT. ANOTHER
SYSTEM WILL PASS TO THE SOUTHWEST OF THE LAKE EARLY/MIDDLE PART OF
NEXT WEEK WITH WINDS FRESHENING UP A BIT...BUT SYSTEM SHOULD BE
WEAK ENOUGH AND FAR ENOUGH AWAY TO NOT CAUSE ANY MAJOR
WINDS/WAVES.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 AM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 9 AM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
330 AM CST FRI MAR 1 2013
.DISCUSSION...
330 AM CST
FORECAST CONCERNS ARE LAKE EFFECT SNOW SHOWER POTENTIAL THE NEXT FEW
DAYS...COLD TEMPERATURES OVER THE WEEKEND...AND A POSSIBLE SNOW
PRODUCING SYSTEM EARLY NEXT WEEK.
SHORT TERM...TODAY THROUGH SUNDAY NIGHT...
SLIGHTLY COLDER AIR MASS WILL SETTLE OVER THE REGION TODAY ON
CONTINUED NORTHERLY FLOW...WITH A LARGE AREA OF HIGH PRESSURE
BUILDING IN FROM THE NORTH. THIS SHOULD KEEP HIGHS A FEW DEGREES
COOLER THAN YESTERDAY. LAKE EFFECT SET UP IS QUITE MARGINAL
THERMODYNAMICALLY...BUT COMPENSATING SOMEWHAT WILL BE GOOD
CONVERGENCE AND FETCH WITH NORTH-NORTHEAST LOW LEVEL FLOW. THE
CONVERGENCE AND EVEN SOME ENHANCED LIFT IS BEST ALIGNED OVER
ILLINOIS AND PORTION OF NW INDIANA LAKEFRONT THROUGH MID/LATE
MORNING...SO BUMPED UP POPS SOME FROM PREVIOUS FORECAST. COULD SEE
SOME VERY LIGHT ACCUMULATIONS. OUTSIDE OF LAKE EFFECT...THERE MAY BE
SOME FLURRIES INLAND. ALTHOUGH STRATUS CAN CLEAR OUT QUICKER THIS
TIME OF YEAR DUE TO HIGHER SUN ANGLE...THINK THE NAM IS BEING WAY
TOO AGGRESSIVE WITH CLEARING TREND FROM NORTH. USED RAP GUIDANCE FOR
NEAR TERM SKY FORECAST. MOST OF CWA SHOULD SEE OVC THROUGH DAYLIGHT
HOURS.
THE SAME GENERAL IDEA OF DECENT CONVERGENCE BUT VERY MARGINAL
THERMODYNAMICS AND INVERSION HEIGHTS CONTINUES THROUGH SATURDAY WITH
THE LAKE EFFECT. WILL CONTINUE TO CARRY CHANCE POPS...THOUGH THEY
WILL SLIDE INTO NW INDIANA ON SATURDAY AS NORTHERLY FLOW BECOMES
JUST WEST OF DUE NORTH. SKIES SHOULD START TO CLEAR BY DAYBREAK OVER
THE NW CWA...SO TEMPERATURES SHOULD DROP PRETTY WELL THERE GIVEN
THE GOOD RADIATION COOLING...PROBABLY INTO THE MID TEENS.
OUTSIDE OF LAKE EFFECT CONCERNS...THE ONLY FOCUS OVER THE WEEKEND
WAS TEMPERATURES WITH HIGH PRESSURE BUILDING OVERHEAD. FOR HIGHS
ON SATURDAY...SUSPECT THAT THE MARCH SUN WILL GO TO WORK ON THE
SNOW COVER...ESPECIALLY FOR AREAS THAT DIDNT SEE MUCH THIS WEEK.
FOR MARCH 1-15...WITH 850 TEMPS AROUND -10C AS IS PROGGED ON
SATURDAY...MEDIAN HIGH AT ORD IS 34 DEGREES. WENT JUST UNDER THAT
IN NORTHERN CWA/ESPECIALLY IN THE NORTHEAST WHERE SNOW PACK IS
DEEPEST...YIELDING HIGHS AROUND 30. TO THE SOUTH OF I-80...SUSPECT
WE`LL SEE SOME MID TO EVEN UPPER 30S AS SUN EATS AWAY AT MEAGER
SNOW COVER.
THEN SUNDAY NIGHT...THERE IS A STRONG SIGNAL FOR GOOD RADIATIONAL
COOLING...ESPECIALLY ON THE ECMWF...WHICH MAY BE A BIT TOO
AGGRESSIVE WITH ITS ZERO TO SLIGHTLY BELOW ZERO NUMBERS FOR NORTH
CENTRAL IL. BASICALLY CONTINUED IDEA OF PREVIOUS FORECAST WITH
POTENTIAL FOR SINGLE DIGIT LOWS WEST OF FOX RIVER. ON SUNDAY...THE
COLD START MAY KEEP TEMPS IN CHECK SOMEWHAT...BUT MARCH SUN ANGLE
AND LONGER DAYLIGHT HOURS EXPECTED TO COMPENSATE...IN ADDITION TO
SLIGHTLY WARMER TEMPS ALOFT. MEDIAN ORD HIGHS FOR DAYS WITH 850
TEMPS AS PROGGED ON SUNDAY IN -6 TO -8 RANGE IS 38. DIDNT GO THIS
MILD DUE TO COLD START AND SNOW COVER OVER NORTHERN CWA...BUT
BUMPED UP TEMPS A FEW DEGREES FROM PREVIOUS. IF SNOW COVER CAN BE
ELIMINATED ON SATURDAY OVER SOUTH...WOULDNT BE SURPRISED IF SOME
LOCATIONS TAG 40 DEGREES...BUT FOR NOW WENT WITH UPPER 30S IN
CENTRAL IL. INCREASING CLOUD COVER SHOULD RESULT IN LOWS SEVERAL
DEGREES WARMER SUNDAY NIGHT THAN SATURDAY NIGHT.
LONG TERM...MONDAY THROUGH THURSDAY
MAIN FOCUS IS ON VERY ENERGETIC CLIPPER SYSTEM EARLY NEXT WEEK.
THERE HAVE BEEN FAIRLY SIGNIFICANT RUN TO RUN CHANGES WITH THE
TIMING AND TRACK OF THE STRONG UPPER LOW AND SURFACE REFLECTION.
WOULD EXPECT THIS TO CONTINUE UNTIL UPPER WAVE MAKES LANDFALL IN
PACIFIC NORTHWEST SATURDAY NIGHT ALLOWING FOR SAMPLING BY RAOB
NETWORK. AS IT STANDS RIGHT NOW...00Z GUIDANCE HAS SHIFTED BACK
NORTH...WHICH WOULD PUT MOST OF CWA IN LINE FOR A POTENTIALLY
ACCUMULATING SNOW. COULD SEE THE START OF SOME WAA SNOWS AHEAD OF
SYSTEM ON MONDAY...SO BLENDED POPS WERE MAINTAINED.
HOWEVER...BIGGEST CHANGE WAS TO GREATLY INCREASE POPS ABOVE
ALLBLEND MONDAY NIGHT AND TUESDAY IN LINE WITH A SLOWER
PROGRESSION OF THE UPPER LOW AND ATTENDANT SURFACE LOW FAVORED BY
THE 00Z ECMWF...CANADIAN...GEFS AND HPC. GFS APPEARS MUCH TOO FAST
IN CLEARING THE SYSTEM OFF TO THE EAST. FOR NOW...BUMPED UP POPS
TO MID RANGE CHANCE GIVEN UNCERTAINTY.
AS CURRENTLY MODELED...THE UPPER LOW WITH THIS SYSTEM LOOKS QUITE
STRONG...WITH A TIGHT BAROCLINIC ZONE ALONG/AHEAD OF ITS TRACK. THUS
THERE COULD BE A NICE SWATH OF SNOW PUT DOWN SOMEWHERE OVER/NEAR THE
REGION. ON THE NEGATIVE SIDE...TEMPERATURES AS IS USUALLY THE CASE
IN MARCH WOULD BE NEAR FREEZING...SO THE SNOW WOULD HAVE TO COME
DOWN HARD TO ACCUMULATE EFFICIENTLY. LOTS OF TIME TO MONITOR THIS
SYSTEM.
FOR THE REST OF THE EXTENDED AND BEYOND...AFTER A FAIRLY COOL DAY ON
WEDNESDAY BEHIND THE EARLY WEEK SYSTEM...THERE COULD BE BRIEF WARM UP
TO NORMAL TO ABOVE NORMAL AS THE PATTERN TRANSITIONS FROM AN EASTERN
TROUGH/WESTERN RIDGE (POSITIVE PNA) CONFIGURATION TO A WESTERN
TROUGH/EASTERN RIDGE (NEGATIVE PNA) PATTERN. WITH RIDGING FIRST
AMPLIFYING INTO CENTER OF CONUS...WE COULD SEE A FEW DAYS OF
TEMPERATURES AT LEAST BACK INTO THE 40S.
HOWEVER...THE LONG RANGE ENSEMBLES LOOKING BEYOND THIS 7 DAY
FORECAST PERIOD ARE HOLDING ONTO THE IDEA OF MAINTAINING HIGH
LATITUDE BLOCKING/NEGATIVE NAO AND NEGATIVE AO THROUGH MID MARCH.
IN ADDITION...RIDGING MAY AMPLIFY OVER OR NEAR ALASKA WHICH ALLOWS
FRESH COLD AIR TO INFILTRATE CANADA AND THE NORTHERN CONUS. BOTTOM
LINE IS ANY WARM UP COULD BE QUICKLY FOLLOWED BY A RETURN TO THE
COLDER THAN NORMAL PATTERN. NO MARCH 2012 PATTERN IS SEEN IN THE
EXTENDED FOR ANYONE HOPING FOR AN EARLY SUMMER AGAIN.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* OCCASIONAL FLURRIES AND POSSIBLY SCT -SHSN...ESPECIALLY THRU
EARLY FRI AFTERNOON
* NNW WINDS TO TRANSITION TO NE FRIDAY MORNING
IZZI
//DISCUSSION...UPDATED 06Z...
EXTENSIVE HIGH END MVFR/LOW END VFR STRATUS DECK BLANKETS THE
REGION WITH SOME POCKETS OF FLURRIES/VERY LIGHT SNOW SHOWERS
LIKELY TO TO PERSIST THRU THE TAF CYCLE. LAKE EFFECT SNOW SHOWERS
WILL HAVE A TENDENCY TO BACK WEST INTO NE IL FRIDAY MORNING AND
COULD BRING SOME TEMPO VSBY RESTRICTIONS TO MVFR AND POSSIBLY
BRIEFLY IFR IN -SN TO ORD/MDW FRI MORNING/EARLY AFTERNOON. LAND
BREEZE INFLUENCE TO WIND DIRECTION SHOULD RESULT IN WEST OF DUE
NORTH WINDS INTO EARLY FRIDAY MORNING AT CHGO AREA TERMINALS WITH
TRANSITION TO MORE NE WINDS EXPECTED AT SOME POINT FRIDAY MORNING.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* LOW/MEDIUM CONFIDENCE IN -SHSN POTENTIAL
* HIGH CONFIDENCE IN WIND SHIFT TO NE...BUT LOW CONFIDENCE IN
TIMING
* MEDIUM/HIGH CONFIDENCE IN CIGS FORECAST THROUGH THE PERIOD
IZZI
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY AND SUNDAY...VFR.
MONDAY AND TUESDAY...CHANCE FOR SNOW AND MVFR.
WEDNESDAY...VFR.
MDB
&&
.MARINE...
222 AM CST
MODERATELY STRONG NORTH WINDS LIKELY TO CONTINUE THROUGH SATURDAY
WITH OCCASIONAL GALE FORCE GUSTS A POSSIBILITY...ESPECIALLY LATER
THIS AFTERNOON INTO THE EVENING...BUT GENERALLY THINK ANY GALES
WILL BE INFREQUENT ENOUGH TO KEEP OUT OF THE FORECAST. WINDS WILL
BEGIN TO DIMINISHING LATER SATURDAY INTO SUNDAY AS RIDGE AXIS
APPROACHES AND THEN MOVES ACROSS THE LAKE SUNDAY NIGHT. ANOTHER
SYSTEM WILL PASS TO THE SOUTHWEST OF THE LAKE EARLY/MIDDLE PART OF
NEXT WEEK WITH WINDS FRESHENING UP A BIT...BUT SYSTEM SHOULD BE
WEAK ENOUGH AND FAR ENOUGH AWAY TO NOT CAUSE ANY MAJOR
WINDS/WAVES.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
531 PM EST FRI MAR 1 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 257 PM EST FRI MAR 1 2013
ONE LAST DISTURBANCE SLIDING AROUND THE PERIPHERY OF THE LARGE UPPER
LOW TO THE NORTHEAST WILL PUSH THROUGH THE REGION EARLY THIS
EVENING...WITH CONTINUED POTENTIAL FOR LIGHT SNOW SHOWERS OR
FLURRIES IN PORTIONS OF THE SOUTHERN FORECAST AREA. HIGH PRESSURE AT
THE SURFACE WILL RETURN DRY WEATHER TO THE AREA THROUGH THE WEEKEND.
ANOTHER DISTURBANCE IN NORTHWEST FLOW ALOFT MAY PUSH THROUGH THE
AREA EARLY NEXT WEEK...MONDAY NIGHT THROUGH TUESDAY NIGHT WITH
ADDITIONAL PRECIPITATION CHANCES ASSOCIATED WITH IT. HIGH
PRESSURE...DRY WEATHER AND WARMER TEMPERATURES ARE IN STORE FOR THE
END OF NEXT WEEK.
&&
.NEAR TERM /TONIGHT/...
ISSUED AT 257 PM EST FRI MAR 1 2013
PER LATEST RADAR MOSAIC TRENDS AND MOST RECENT HRRR RUN DEPICT SNOW
SHOWERS/FLURRIES AND EVEN SOME DRIZZLE ACROSS THE SOUTH WILL BE A
LITTLE SLOWER IN EXITING THE FORECAST AREA. LEFT IN LOW CHANCES FOR
PRECIP ACROSS THE SOUTH FOR THIS EVENING...THEN WENT DRY FOR THE
OVERNIGHT. BASED ON PERSISTENCE AND THE FACT THAT CLOUDS AND EVEN TO
SOME EXTENT SOME PRECIPITATION WILL HANG AROUND A WHILE
LONGER...BUMPED UP OVERNIGHT LOWS ABOUT 5 DEGREES ABOVE MOS WHICH
YIELDS LOWS IN THE MID TO UPPER 20S.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
ISSUED AT 257 PM EST FRI MAR 1 2013
IT/S LOOKING LIKE A DRY WEEKEND. SURFACE HIGH PRESSURE WILL BUILD
OVER THE AREA AND REMAIN THE DOMINANT WEATHER FIXTURE FOR THE
WEEKEND. MOSTLY CLOUDY SKIES APPEAR TO LINGER OVER CENTRAL INDIANA
FOR THE FIRST HALF OF THE WEEKEND BUT THE COLUMN FINALLY BEGINS TO
DRY OUT BY SUNDAY...ALLOWING MOSTLY SUNNY TO PARTLY CLOUDY SKIES TO
RETURN TO THE AREA. NORTHERLY FLOW WILL KEEP TEMPERATURE BELOW
NORMAL THROUGH THE WEEKEND. NEXT SYSTEM TO IMPACT THE REGION COME
SOMETIME MONDAY OR MONDAY NIGHT. THERE A STARK DIFFERENCE WITH
RESPECT TO TIMING...WITH THE GFS BEING QUITE A FAST AND PROGRESSIVE
OUTLIER...SO LEANED TOWARD THE REST OF THE SLOWER GUIDANCE AND ONLY
INTRODUCED LOW CHANCE POPS LATE IN THE DAY MONDAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ISSUED AT 257 PM EST FRI MAR 1 2013
THE EXTENDED PERIOD WILL START OUT RATHER ACTIVE AS A SURFACE LOW
FROM THE SOUTHERN PLAINS EVENTUALLY MERGES WITH AN UPPER LEVEL LOW
COMING OUT OF THE NORTHERN PLAINS ON TUESDAY. THE SURFACE LOW WILL
REACH CENTRAL INDIANA FIRST THOUGH BRINGING RAIN AND SNOW CHANCES ON
MONDAY. THE GFS AND EURO CONTINUE TO DIFFER ON TRACK OF UPPER LEVEL
LOW WITH THE GFS DIGGING IT FURTHER INTO THE TENNESSEE VALLEY WHILE
STRENGTHENING IT. MEANWHILE...THE EURO TAKES IT ACROSS CENTRAL
INDIANA AND NOT AS TIGHTLY WRAPPED. FOR NOW...WILL STICK WITH
INITIALIZATION WHICH SEEMS TO BE FAVORING THE GFS A TAD BY
INDICATING LIKELY POPS ACROSS THE SOUTHEAST PORTIONS OF CENTRAL
INDIANA ON TUESDAY.
PRECIP WILL DIMINISH FROM WEST TO EAST ON TUESDAY NIGHT/WEDNESDAY
MORNING WITH ALL PRECIP OUT OF THE AREA BY WEDNESDAY AFTERNOON.
THAT/S WHEN A LARGE RIDGE WILL MOVE INTO CENTRAL INDIANA BRINGING
DRY WEATHER FOR THE REMAINDER OF THE LONG TERM PERIOD. TEMPS WILL
BE SLIGHTLY BELOW NORMAL AT FIRST...BUT WARM UP BY THE END OF THE
EXTENDED PERIOD. INITIALIZATION NUMBERS LOOK REASONABLE...SO WILL
NOT DEVIATE.
&&
.AVIATION /DISCUSSION FOR THE 020000Z TAFS/...
ISSUED AT 531 PM EST FRI MAR 1 2013
WEAK SURFACE TROUGH CURRENTLY PUSHING SOUTH THROUGH THE SOUTHERN
SECTIONS OF THE FORECAST AREA. AREAS OF IFR CEILINGS/VISIBILITIES IN
LIGHT SNOW/DRIZZLE ASSOCIATED WITH THIS FEATURE..SO EXPECTING THESE
CONDITIONS TO AFFECT KHUF/KBMG THROUGH ABOUT 020200Z.
OTHERWISE...LARGE AREA OF MVFR CEILINGS AROUND 020 ACROSS THE OHIO
VALLEY EXPECTED TO LINGER TONIGHT UNDER AN INVERSION BELOW 035-040.
SURFACE WINDS GENERALLY UNDER 10 KTS AT THE TAF SITES THROUGH
021200Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SMF
NEAR TERM...SMF
SHORT TERM...SMF
LONG TERM....TDUD
AVIATION...JAS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
325 PM EST FRI MAR 1 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 257 PM EST FRI MAR 1 2013
ONE LAST DISTURBANCE SLIDING AROUND THE PERIPHERY OF THE LARGE UPPER
LOW TO THE NORTHEAST WILL PUSH THROUGH THE REGION EARLY THIS
EVENING...WITH CONTINUED POTENTIAL FOR LIGHT SNOW SHOWERS OR
FLURRIES IN PORTIONS OF THE SOUTHERN FORECAST AREA. HIGH PRESSURE AT
THE SURFACE WILL RETURN DRY WEATHER TO THE AREA THROUGH THE WEEKEND.
ANOTHER DISTURBANCE IN NORTHWEST FLOW ALOFT MAY PUSH THROUGH THE
AREA EARLY NEXT WEEK...MONDAY NIGHT THROUGH TUESDAY NIGHT WITH
ADDITIONAL PRECIPITATION CHANCES ASSOCIATED WITH IT. HIGH
PRESSURE...DRY WEATHER AND WARMER TEMPERATURES ARE IN STORE FOR THE
END OF NEXT WEEK.
&&
.NEAR TERM /TONIGHT/...
ISSUED AT 257 PM EST FRI MAR 1 2013
PER LATEST RADAR MOSAIC TRENDS AND MOST RECENT HRRR RUN DEPICT SNOW
SHOWERS/FLURRIES AND EVEN SOME DRIZZLE ACROSS THE SOUTH WILL BE A
LITTLE SLOWER IN EXITING THE FORECAST AREA. LEFT IN LOW CHANCES FOR
PRECIP ACROSS THE SOUTH FOR THIS EVENING...THEN WENT DRY FOR THE
OVERNIGHT. BASED ON PERSISTENCE AND THE FACT THAT CLOUDS AND EVEN TO
SOME EXTENT SOME PRECIPITATION WILL HANG AROUND A WHILE
LONGER...BUMPED UP OVERNIGHT LOWS ABOUT 5 DEGREES ABOVE MOS WHICH
YIELDS LOWS IN THE MID TO UPPER 20S.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
ISSUED AT 257 PM EST FRI MAR 1 2013
IT/S LOOKING LIKE A DRY WEEKEND. SURFACE HIGH PRESSURE WILL BUILD
OVER THE AREA AND REMAIN THE DOMINANT WEATHER FIXTURE FOR THE
WEEKEND. MOSTLY CLOUDY SKIES APPEAR TO LINGER OVER CENTRAL INDIANA
FOR THE FIRST HALF OF THE WEEKEND BUT THE COLUMN FINALLY BEGINS TO
DRY OUT BY SUNDAY...ALLOWING MOSTLY SUNNY TO PARTLY CLOUDY SKIES TO
RETURN TO THE AREA. NORTHERLY FLOW WILL KEEP TEMPERATURE BELOW
NORMAL THROUGH THE WEEKEND. NEXT SYSTEM TO IMPACT THE REGION COME
SOMETIME MONDAY OR MONDAY NIGHT. THERE A STARK DIFFERENCE WITH
RESPECT TO TIMING...WITH THE GFS BEING QUITE A FAST AND PROGRESSIVE
OUTLIER...SO LEANED TOWARD THE REST OF THE SLOWER GUIDANCE AND ONLY
INTRODUCED LOW CHANCE POPS LATE IN THE DAY MONDAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ISSUED AT 257 PM EST FRI MAR 1 2013
THE EXTENDED PERIOD WILL START OUT RATHER ACTIVE AS A SURFACE LOW
FROM THE SOUTHERN PLAINS EVENTUALLY MERGES WITH AN UPPER LEVEL LOW
COMING OUT OF THE NORTHERN PLAINS ON TUESDAY. THE SURFACE LOW WILL
REACH CENTRAL INDIANA FIRST THOUGH BRINGING RAIN AND SNOW CHANCES ON
MONDAY. THE GFS AND EURO CONTINUE TO DIFFER ON TRACK OF UPPER LEVEL
LOW WITH THE GFS DIGGING IT FURTHER INTO THE TENNESSEE VALLEY WHILE
STRENGTHENING IT. MEANWHILE...THE EURO TAKES IT ACROSS CENTRAL
INDIANA AND NOT AS TIGHTLY WRAPPED. FOR NOW...WILL STICK WITH
INITIALIZATION WHICH SEEMS TO BE FAVORING THE GFS A TAD BY
INDICATING LIKELY POPS ACROSS THE SOUTHEAST PORTIONS OF CENTRAL
INDIANA ON TUESDAY.
PRECIP WILL DIMINISH FROM WEST TO EAST ON TUESDAY NIGHT/WEDNESDAY
MORNING WITH ALL PRECIP OUT OF THE AREA BY WEDNESDAY AFTERNOON.
THAT/S WHEN A LARGE RIDGE WILL MOVE INTO CENTRAL INDIANA BRINGING
DRY WEATHER FOR THE REMAINDER OF THE LONG TERM PERIOD. TEMPS WILL
BE SLIGHTLY BELOW NORMAL AT FIRST...BUT WARM UP BY THE END OF THE
EXTENDED PERIOD. INITIALIZATION NUMBERS LOOK REASONABLE...SO WILL
NOT DEVIATE.
&&
.AVIATION /DISCUSSION FOR THE 012100Z TAF UPDATE/...
ISSUED AT 325 PM EST FRI MAR 1 2013
NO SIGNIFICANT CHANGES MADE TO KIND TAF. SOME LIGHT SNOW AND DRIZZLE
WILL CONTINUE AT KIND FOR PERHAPS A COUPLE MORE HOURS...BUT NOT
EXPECTING ANY ADDITIONAL VISIBILITY RESTRICTIONS. CEILINGS SHOULD
GRADUALLY LIFT TO AT OR ABOVE BKN020 BY 23Z OR SO.
PREVIOUS DISCUSSION FOLLOWS...
BRIEF IFR CONDITIONS AT A FEW ISOLATED TAF SITES IS EXPECTED TO
IMPROVE TO MVFR THIS AFTERNOON FOR THE REST OF THE TAF PERIOD.
BROAD CYCLONIC FLOW IS EXPECTED TO PERSIST THE NEXT 24 HOURS AS
STRONG RIDGING ALOFT REMAINS TO THE WEST AND A DEEP TROUGH REMAINS
OVER THE EASTERN UNITED STATES. TIME HEIGHT SECTIONS CONTINUE TO
SHOW SATURATED LOWER LEVELS THROUGH SATURDAY...WITH CCL GENERALLY
LESS THAN 3000 FT. THUS MVFR CIGS ARE EXPECTED THROUGH MUCH OF THE
PERIOD WITH NORTH WINDS OF 5 TO 10 MPH.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SMF
NEAR TERM...SMF
SHORT TERM...SMF
LONG TERM....TDUD
AVIATION...JP/50
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
259 PM EST FRI MAR 1 2013
.UPDATE...
THE SYNOPSIS...NEAR TERM...SHORT TERM AND LONG TERM SECTIONS HAVE
BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 257 PM EST FRI MAR 1 2013
ONE LAST DISTURBANCE SLIDING AROUND THE PERIPHERY OF THE LARGE UPPER
LOW TO THE NORTHEAST WILL PUSH THROUGH THE REGION EARLY THIS
EVENING...WITH CONTINUED POTENTIAL FOR LIGHT SNOW SHOWERS OR
FLURRIES IN PORTIONS OF THE SOUTHERN FORECAST AREA. HIGH PRESSURE AT
THE SURFACE WILL RETURN DRY WEATHER TO THE AREA THROUGH THE WEEKEND.
ANOTHER DISTURBANCE IN NORTHWEST FLOW ALOFT MAY PUSH THROUGH THE
AREA EARLY NEXT WEEK...MONDAY NIGHT THROUGH TUESDAY NIGHT WITH
ADDITIONAL PRECIPITATION CHANCES ASSOCIATED WITH IT. HIGH
PRESSURE...DRY WEATHER AND WARMER TEMPERATURES ARE IN STORE FOR THE
END OF NEXT WEEK.
&&
.NEAR TERM /TONIGHT/...
ISSUED AT 257 PM EST FRI MAR 1 2013
PER LATEST RADAR MOSAIC TRENDS AND MOST RECENT HRRR RUN DEPICT SNOW
SHOWERS/FLURRIES AND EVEN SOME DRIZZLE ACROSS THE SOUTH WILL BE A
LITTLE SLOWER IN EXITING THE FORECAST AREA. LEFT IN LOW CHANCES FOR
PRECIP ACROSS THE SOUTH FOR THIS EVENING...THEN WENT DRY FOR THE
OVERNIGHT. BASED ON PERSISTENCE AND THE FACT THAT CLOUDS AND EVEN TO
SOME EXTENT SOME PRECIPITATION WILL HANG AROUND A WHILE
LONGER...BUMPED UP OVERNIGHT LOWS ABOUT 5 DEGREES ABOVE MOS WHICH
YIELDS LOWS IN THE MID TO UPPER 20S.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
ISSUED AT 257 PM EST FRI MAR 1 2013
IT/S LOOKING LIKE A DRY WEEKEND. SURFACE HIGH PRESSURE WILL BUILD
OVER THE AREA AND REMAIN THE DOMINANT WEATHER FIXTURE FOR THE
WEEKEND. MOSTLY CLOUDY SKIES APPEAR TO LINGER OVER CENTRAL INDIANA
FOR THE FIRST HALF OF THE WEEKEND BUT THE COLUMN FINALLY BEGINS TO
DRY OUT BY SUNDAY...ALLOWING MOSTLY SUNNY TO PARTLY CLOUDY SKIES TO
RETURN TO THE AREA. NORTHERLY FLOW WILL KEEP TEMPERATURE BELOW
NORMAL THROUGH THE WEEKEND. NEXT SYSTEM TO IMPACT THE REGION COME
SOMETIME MONDAY OR MONDAY NIGHT. THERE A STARK DIFFERENCE WITH
RESPECT TO TIMING...WITH THE GFS BEING QUITE A FAST AND PROGRESSIVE
OUTLIER...SO LEANED TOWARD THE REST OF THE SLOWER GUIDANCE AND ONLY
INTRODUCED LOW CHANCE POPS LATE IN THE DAY MONDAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ISSUED AT 257 PM EST FRI MAR 1 2013
THE EXTENDED PERIOD WILL START OUT RATHER ACTIVE AS A SURFACE LOW
FROM THE SOUTHERN PLAINS EVENTUALLY MERGES WITH AN UPPER LEVEL LOW
COMING OUT OF THE NORTHERN PLAINS ON TUESDAY. THE SURFACE LOW WILL
REACH CENTRAL INDIANA FIRST THOUGH BRINGING RAIN AND SNOW CHANCES ON
MONDAY. THE GFS AND EURO CONTINUE TO DIFFER ON TRACK OF UPPER LEVEL
LOW WITH THE GFS DIGGING IT FURTHER INTO THE TENNESSEE VALLEY WHILE
STRENGTHENING IT. MEANWHILE...THE EURO TAKES IT ACROSS CENTRAL
INDIANA AND NOT AS TIGHTLY WRAPPED. FOR NOW...WILL STICK WITH
INITIALIZATION WHICH SEEMS TO BE FAVORING THE GFS A TAD BY
INDICATING LIKELY POPS ACROSS THE SOUTHEAST PORTIONS OF CENTRAL
INDIANA ON TUESDAY.
PRECIP WILL DIMINISH FROM WEST TO EAST ON TUESDAY NIGHT/WEDNESDAY
MORNING WITH ALL PRECIP OUT OF THE AREA BY WEDNESDAY AFTERNOON.
THAT/S WHEN A LARGE RIDGE WILL MOVE INTO CENTRAL INDIANA BRINGING
DRY WEATHER FOR THE REMAINDER OF THE LONG TERM PERIOD. TEMPS WILL
BE SLIGHTLY BELOW NORMAL AT FIRST...BUT WARM UP BY THE END OF THE
EXTENDED PERIOD. INITIALIZATION NUMBERS LOOK REASONABLE...SO WILL
NOT DEVIATE.
&&
.AVIATION /DISCUSSION FOR THE 011800Z TAFS/...
ISSUED AT 1118 AM EST FRI MAR 1 2013
BRIEF IFR CONDITIONS AT A FEW ISOLATED TAF SITES IS EXPECTED TO
IMPROVE TO MVFR THIS AFTERNOON FOR THE REST OF THE TAF PERIOD.
BROAD CYCLONIC FLOW IS EXPECTED TO PERSIST THE NEXT 24 HOURS AS
STRONG RIDGING ALOFT REMAINS TO THE WEST AND A DEEP TROUGH REMAINS
OVER THE EASTERN UNITED STATES. TIME HEIGHT SECTIONS CONTINUE TO
SHOW SATURATED LOWER LEVELS THROUGH SATURDAY...WITH CCL GENERALLY
LESS THAN 3000 FT. THUS MVFR CIGS ARE EXPECTED THROUGH MUCH OF THE
PERIOD WITH NORTH WINDS OF 5 TO 10 MPH.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SMF
NEAR TERM...SMF
SHORT TERM...SMF
LONG TERM....TDUD
AVIATION...JP
AREA FORECAST DISCUSSION...CORRECTED
NWS NORTHERN INDIANA
100 PM EST FRI MAR 1 2013
.AVIATION... /18 UTC TAFS/
SLIGHT IMPROVEMENT WRT FLIGHT CONDS THIS AFTN WITH INCRSD
MIXING/DEPTH OF BLYR. ANTICIPATE CONTD ALBEIT SLIGHT ERORSIVE
DOWNWARD VERTICAL MOTION TO MAINTAIN PRIMARILY VFR CONDS OVERNIGHT.
SLIGHT INCR IN MSTR PER BACKING WIND FLOW ACRS LK MI ON SAT MAY
AFFORD HIR END MVFR CIGS ACRS NRN IN WITH SCT FLURRIES/SPCLY INVOF
KSBN.
&&
.PREV DISCUSSION... /ISSUED 444 AM EST FRI MAR 1 2013/
SHORT TERM...TODAY THROUGH SATURDAY NIGHT
RELATIVELY QUIET PERIOD IN STORE FOR THE UPCOMING WEEKEND WITH MAIN
SHORT TERM FOCUS ON LINGERING LIGHT PRECIP THIS MORNING...AND
TEMPERATURE TRENDS.
WATER VAPOR IMAGERY/07Z RAP ANALYSIS SUGGEST WEAK UPPER VORT MAX
DROPPING SOUTHWARD ACROSS NORTHERN INDIANA THIS MORNING. HAVE NOTED
SOME UPSWING OVER PAST HOUR ACROSS CENTRAL/SOUTHERN SECTIONS OF
FORECAST AREA OF SOME -FZDZ PER RADAR/SFC OBSERVATIONS BUT FZDZ IS
EXPECTED TO REMAIN LIGHT ENOUGH TO PREVENT SIGNIFICANT IMPACTS THIS
MORNING. WITH AXIS OF WEAK DPVA SHIFTING ACROSS SOUTHERN/CENTRAL
AREAS WILL CONFINE EARLY MORNING FZDZ MENTION TO THESE LOCATIONS
WITH MAINLY DRY CONDITIONS ACROSS THE NORTH WERE LOW LEVEL DRY AIR
ADVECTION HAS BECOME MORE PRONOUNCED IN THE WAKE OF ASSOCIATED WEAK
INVERTED SFC TROUGH FEATURE. MARINE OBS SUGGEST SOME AUGMENTATION TO
SYNOPTIC CONVERGENCE ASSOCIATED WITH THIS TROUGH WITH WEAK LAKE
INDUCED THERMAL TROUGHING. THIS MAY ACT TO PERPETUATE SOME FLURRIES
ACROSS EXTREME NORTHWEST SECTIONS OF THE FORECAST AREA
TODAY...ALTHOUGH INCREASINGLY DRY LOW LEVEL AIR MASS SHOULD LIMIT
FLURRY/LIGHT SNOW SHOWER ACTIVITY. LIMITED DIURNAL MOVEMENT IN
TEMPERATURES EXPECTED AGAIN TODAY WITH RELATIVELY WEAK THERMAL
ADVECTION AND PERSISTENCE OF LOW CLOUD DECK.
FOR TONIGHT INTO SATURDAY...LONGWAVE RIDING ACROSS WESTERN CONUS
WILL BEGIN TO SHIFT EASTWARD AS WEAK UPPER PV ANOMALY ACROSS
NORTHERN PLAINS ADVANCES INTO THE WESTERN GREAT LAKES REGION. UPPER
FORCING/DYNAMICS LOOK TO BE QUITE WEAK WITH THIS SHORT WAVE HOWEVER
AS PV ANOMALY BECOMES AFFECTED BY MID/UPPER LEVEL DEFORMATION FLOW
ACROSS GREAT LAKES REGION. PASSAGE OF THIS FEATURE MAY MARK A SUBTLE
UPSWING IN WEAK LAKE RESPONSE IN THE FORM OF SCT FLURRIES/LIGHT SNOW
SHOWERS SATURDAY/SATURDAY NIGHT. LAKE EFFECT PARAMETERS QUITE MEAGER
HOWEVER WITH VERY DRY MID LEVEL AIR IN PLACE...AND MARGINAL LAKE/850
HPA DELTA TEMPS. DESPITE SOME WEAK REINFORCING LOW LEVEL CAA WITH
AFOREMENTIONED NORTHERN PLAINS SHORT WAVE SATURDAY...HIGH TEMPS
SHOULD BE SIMILAR TO THAT OF FRIDAY WITH THE POSSIBILITY OF A BIT
MORE INSOLATION OFFSETTING SLIGHTLY COOLER LOW LEVEL THERMAL
PROFILES.
&&
LONG TERM...
SUNDAY THROUGH THURSDAY...THE MAIN CHALLENGE THIS PERIOD IS THE
TIMING AND TRACK OF A SHORT WAVE THAT WILL TOP THE UPSTREAM RIDGE
AND MOVE INTO THE MIDWEST NEXT WEEK. THE ECMWF APPEARS TO HAVE
INITIALIZED THIS SYSTEM REASONABLY WELL AND HAS ALSO SHOWN SOME RUN
TO RUN CONSISTENCY. FOR THIS PACKAGE...BLENDED SEVERAL MODELS
INCLUDING THE ECMWF OPERATIONAL RUN...EC ENSEMBLE MEAN...AND GFS
OPERATIONAL RUN WITH ENSEMBLE MEMBERS. GIVEN THE HIGH LATITUDE
STRONG POSITIVE ANOMALY...CONCERN THAT THESE MODELS MAY BE TOO FAST
WITH THIS SYSTEM. THE ECMWF HAS TRENDED SLIGHTLY SLOWER WITH THIS
SYSTEM WITH AN ARRIVAL TIME OF TUESDAY/TUESDAY NIGHT. HAVE TRENDED
THE SNOW CHANCES HIGHER THESE PERIODS...BUT KEPT IN CHANCE CATEGORY
DUE TO A LARGE GFS ENSEMBLE SPREAD AND LARGE NORMALIZED STANDARD
DEVIATIONS AMONG ECMWF ENSEMBLE MEMBERS. A WEAK LAKE RESPONSE IS
EXPECTED AFTER THIS SYSTEM PASSES...BUT DELTA T VALUES SHOULD REMAIN
LESS THAN 10. OTHERWISE...KEPT TEMPERATURES COLD THROUGH WEDNESDAY.
TEMPS SHOULD RISE ABOVE NORMAL THURSDAY AS AN UPPER LEVEL RIDGE
BUILDS OVER THE REGION. GFS MEAN ENSEMBLE MEX MOS TEMPS APPEAR ON
TRACK.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST SUNDAY FOR LMZ043-046.
&&
$$
SHORT TERM...MARSILI
LONG TERM...SKIPPER
AVIATION...MURPHY
CORRECTED ISSUANCE TIME
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
6100 PM EST FRI MAR 1 2013
.AVIATION... /18 UTC TAFS/
SLIGHT IMPROVEMENT WRT FLIGHT CONDS THIS AFTN WITH INCRSD
MIXING/DEPTH OF BLYR. ANTICIPATE CONTD ALBEIT SLIGHT ERORSIVE
DOWNWARD VERTICAL MOTION TO MAINTAIN PRIMARILY VFR CONDS OVERNIGHT.
SLIGHT INCR IN MSTR PER BACKING WIND FLOW ACRS LK MI ON SAT MAY
AFFORD HIR END MVFR CIGS ACRS NRN IN WITH SCT FLURRIES/SPCLY INVOF
KSBN.
&&
.PREV DISCUSSION... /ISSUED 444 AM EST FRI MAR 1 2013/
SHORT TERM...TODAY THROUGH SATURDAY NIGHT
RELATIVELY QUIET PERIOD IN STORE FOR THE UPCOMING WEEKEND WITH MAIN
SHORT TERM FOCUS ON LINGERING LIGHT PRECIP THIS MORNING...AND
TEMPERATURE TRENDS.
WATER VAPOR IMAGERY/07Z RAP ANALYSIS SUGGEST WEAK UPPER VORT MAX
DROPPING SOUTHWARD ACROSS NORTHERN INDIANA THIS MORNING. HAVE NOTED
SOME UPSWING OVER PAST HOUR ACROSS CENTRAL/SOUTHERN SECTIONS OF
FORECAST AREA OF SOME -FZDZ PER RADAR/SFC OBSERVATIONS BUT FZDZ IS
EXPECTED TO REMAIN LIGHT ENOUGH TO PREVENT SIGNIFICANT IMPACTS THIS
MORNING. WITH AXIS OF WEAK DPVA SHIFTING ACROSS SOUTHERN/CENTRAL
AREAS WILL CONFINE EARLY MORNING FZDZ MENTION TO THESE LOCATIONS
WITH MAINLY DRY CONDITIONS ACROSS THE NORTH WERE LOW LEVEL DRY AIR
ADVECTION HAS BECOME MORE PRONOUNCED IN THE WAKE OF ASSOCIATED WEAK
INVERTED SFC TROUGH FEATURE. MARINE OBS SUGGEST SOME AUGMENTATION TO
SYNOPTIC CONVERGENCE ASSOCIATED WITH THIS TROUGH WITH WEAK LAKE
INDUCED THERMAL TROUGHING. THIS MAY ACT TO PERPETUATE SOME FLURRIES
ACROSS EXTREME NORTHWEST SECTIONS OF THE FORECAST AREA
TODAY...ALTHOUGH INCREASINGLY DRY LOW LEVEL AIR MASS SHOULD LIMIT
FLURRY/LIGHT SNOW SHOWER ACTIVITY. LIMITED DIURNAL MOVEMENT IN
TEMPERATURES EXPECTED AGAIN TODAY WITH RELATIVELY WEAK THERMAL
ADVECTION AND PERSISTENCE OF LOW CLOUD DECK.
FOR TONIGHT INTO SATURDAY...LONGWAVE RIDING ACROSS WESTERN CONUS
WILL BEGIN TO SHIFT EASTWARD AS WEAK UPPER PV ANOMALY ACROSS
NORTHERN PLAINS ADVANCES INTO THE WESTERN GREAT LAKES REGION. UPPER
FORCING/DYNAMICS LOOK TO BE QUITE WEAK WITH THIS SHORT WAVE HOWEVER
AS PV ANOMALY BECOMES AFFECTED BY MID/UPPER LEVEL DEFORMATION FLOW
ACROSS GREAT LAKES REGION. PASSAGE OF THIS FEATURE MAY MARK A SUBTLE
UPSWING IN WEAK LAKE RESPONSE IN THE FORM OF SCT FLURRIES/LIGHT SNOW
SHOWERS SATURDAY/SATURDAY NIGHT. LAKE EFFECT PARAMETERS QUITE MEAGER
HOWEVER WITH VERY DRY MID LEVEL AIR IN PLACE...AND MARGINAL LAKE/850
HPA DELTA TEMPS. DESPITE SOME WEAK REINFORCING LOW LEVEL CAA WITH
AFOREMENTIONED NORTHERN PLAINS SHORT WAVE SATURDAY...HIGH TEMPS
SHOULD BE SIMILAR TO THAT OF FRIDAY WITH THE POSSIBILITY OF A BIT
MORE INSOLATION OFFSETTING SLIGHTLY COOLER LOW LEVEL THERMAL
PROFILES.
&&
LONG TERM...
SUNDAY THROUGH THURSDAY...THE MAIN CHALLENGE THIS PERIOD IS THE
TIMING AND TRACK OF A SHORT WAVE THAT WILL TOP THE UPSTREAM RIDGE
AND MOVE INTO THE MIDWEST NEXT WEEK. THE ECMWF APPEARS TO HAVE
INITIALIZED THIS SYSTEM REASONABLY WELL AND HAS ALSO SHOWN SOME RUN
TO RUN CONSISTENCY. FOR THIS PACKAGE...BLENDED SEVERAL MODELS
INCLUDING THE ECMWF OPERATIONAL RUN...EC ENSEMBLE MEAN...AND GFS
OPERATIONAL RUN WITH ENSEMBLE MEMBERS. GIVEN THE HIGH LATITUDE
STRONG POSITIVE ANOMALY...CONCERN THAT THESE MODELS MAY BE TOO FAST
WITH THIS SYSTEM. THE ECMWF HAS TRENDED SLIGHTLY SLOWER WITH THIS
SYSTEM WITH AN ARRIVAL TIME OF TUESDAY/TUESDAY NIGHT. HAVE TRENDED
THE SNOW CHANCES HIGHER THESE PERIODS...BUT KEPT IN CHANCE CATEGORY
DUE TO A LARGE GFS ENSEMBLE SPREAD AND LARGE NORMALIZED STANDARD
DEVIATIONS AMONG ECMWF ENSEMBLE MEMBERS. A WEAK LAKE RESPONSE IS
EXPECTED AFTER THIS SYSTEM PASSES...BUT DELTA T VALUES SHOULD REMAIN
LESS THAN 10. OTHERWISE...KEPT TEMPERATURES COLD THROUGH WEDNESDAY.
TEMPS SHOULD RISE ABOVE NORMAL THURSDAY AS AN UPPER LEVEL RIDGE
BUILDS OVER THE REGION. GFS MEAN ENSEMBLE MEX MOS TEMPS APPEAR ON
TRACK.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST SUNDAY FOR LMZ043-046.
&&
$$
SHORT TERM...MARSILI
LONG TERM...SKIPPER
AVIATION...MURPHY
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
648 AM EST FRI MAR 1 2013
.AVIATION...
12Z TAFS...SHEARED VORTICITY MAXIMUM ACROSS NORTHERN INDIANA WILL
CONTINUE TO TRACK SOUTHWARD EARLY THIS MORNING. INVERTED SFC
TROUGH EXTENDING FROM SOUTHWEST LOWER MICHIGAN TO NEAR KFWA WILL
CONTINUE TO SAG SOUTH AS THIS VORT MAX PROGRESSES SOUTHWARD...AND
THUS EXPECTING AN END TO PATCHY DRIZZLE/FLURRIES AT KFWA BY THE
13Z-14Z TIMEFRAME. OTHERWISE...BRIEF IMPROVEMENTS TO VFR CIGS
POSSIBLE EARLY THIS MORNING...BUT WOULD SUSPECT ENOUGH LINGERING
MOISTURE MAY GIVE RISE TO DIURNALLY ENHANCED MVFR CIGS AGAIN LATE
MORNING INTO THIS AFTERNOON. WINDS HAVE VEERED MORE NORTHEAST
EARLY THIS MORNING IN ASSOCIATION WITH THE INVERTED TROUGH...AND
SHOULD BACK MORE NORTHERLY BY MID MORNING AS THE TROUGH SHIFTS
SOUTHWARD.
&&
.PREV DISCUSSION... /ISSUED 444 AM EST FRI MAR 1 2013/
SHORT TERM...TODAY THROUGH SATURDAY NIGHT
RELATIVELY QUIET PERIOD IN STORE FOR THE UPCOMING WEEKEND WITH MAIN
SHORT TERM FOCUS ON LINGERING LIGHT PRECIP THIS MORNING...AND
TEMPERATURE TRENDS.
WATER VAPOR IMAGERY/07Z RAP ANALYSIS SUGGEST WEAK UPPER VORT MAX
DROPPING SOUTHWARD ACROSS NORTHERN INDIANA THIS MORNING. HAVE NOTED
SOME UPSWING OVER PAST HOUR ACROSS CENTRAL/SOUTHERN SECTIONS OF
FORECAST AREA OF SOME -FZDZ PER RADAR/SFC OBSERVATIONS BUT FZDZ IS
EXPECTED TO REMAIN LIGHT ENOUGH TO PREVENT SIGNIFICANT IMPACTS THIS
MORNING. WITH AXIS OF WEAK DPVA SHIFTING ACROSS SOUTHERN/CENTRAL
AREAS WILL CONFINE EARLY MORNING FZDZ MENTION TO THESE LOCATIONS
WITH MAINLY DRY CONDITIONS ACROSS THE NORTH WERE LOW LEVEL DRY AIR
ADVECTION HAS BECOME MORE PRONOUNCED IN THE WAKE OF ASSOCIATED WEAK
INVERTED SFC TROUGH FEATURE. MARINE OBS SUGGEST SOME AUGMENTATION TO
SYNOPTIC CONVERGENCE ASSOCIATED WITH THIS TROUGH WITH WEAK LAKE
INDUCED THERMAL TROUGHING. THIS MAY ACT TO PERPETUATE SOME FLURRIES
ACROSS EXTREME NORTHWEST SECTIONS OF THE FORECAST AREA
TODAY...ALTHOUGH INCREASINGLY DRY LOW LEVEL AIR MASS SHOULD LIMIT
FLURRY/LIGHT SNOW SHOWER ACTIVITY. LIMITED DIURNAL MOVEMENT IN
TEMPERATURES EXPECTED AGAIN TODAY WITH RELATIVELY WEAK THERMAL
ADVECTION AND PERSISTENCE OF LOW CLOUD DECK.
FOR TONIGHT INTO SATURDAY...LONGWAVE RIDING ACROSS WESTERN CONUS
WILL BEGIN TO SHIFT EASTWARD AS WEAK UPPER PV ANOMALY ACROSS
NORTHERN PLAINS ADVANCES INTO THE WESTERN GREAT LAKES REGION. UPPER
FORCING/DYNAMICS LOOK TO BE QUITE WEAK WITH THIS SHORT WAVE HOWEVER
AS PV ANOMALY BECOMES AFFECTED BY MID/UPPER LEVEL DEFORMATION FLOW
ACROSS GREAT LAKES REGION. PASSAGE OF THIS FEATURE MAY MARK A SUBTLE
UPSWING IN WEAK LAKE RESPONSE IN THE FORM OF SCT FLURRIES/LIGHT SNOW
SHOWERS SATURDAY/SATURDAY NIGHT. LAKE EFFECT PARAMETERS QUITE MEAGER
HOWEVER WITH VERY DRY MID LEVEL AIR IN PLACE...AND MARGINAL LAKE/850
HPA DELTA TEMPS. DESPITE SOME WEAK REINFORCING LOW LEVEL CAA WITH
AFOREMENTIONED NORTHERN PLAINS SHORT WAVE SATURDAY...HIGH TEMPS
SHOULD BE SIMILAR TO THAT OF FRIDAY WITH THE POSSIBILITY OF A BIT
MORE INSOLATION OFFSETTING SLIGHTLY COOLER LOW LEVEL THERMAL
PROFILES.
&&
LONG TERM...
SUNDAY THROUGH THURSDAY...THE MAIN CHALLENGE THIS PERIOD IS THE
TIMING AND TRACK OF A SHORT WAVE THAT WILL TOP THE UPSTREAM RIDGE
AND MOVE INTO THE MIDWEST NEXT WEEK. THE ECMWF APPEARS TO HAVE
INITIALIZED THIS SYSTEM REASONABLY WELL AND HAS ALSO SHOWN SOME RUN
TO RUN CONSISTENCY. FOR THIS PACKAGE...BLENDED SEVERAL MODELS
INCLUDING THE ECMWF OPERATIONAL RUN...EC ENSEMBLE MEAN...AND GFS
OPERATIONAL RUN WITH ENSEMBLE MEMBERS. GIVEN THE HIGH LATITUDE
STRONG POSITIVE ANOMALY...CONCERN THAT THESE MODELS MAY BE TOO FAST
WITH THIS SYSTEM. THE ECMWF HAS TRENDED SLIGHTLY SLOWER WITH THIS
SYSTEM WITH AN ARRIVAL TIME OF TUESDAY/TUESDAY NIGHT. HAVE TRENDED
THE SNOW CHANCES HIGHER THESE PERIODS...BUT KEPT IN CHANCE CATEGORY
DUE TO A LARGE GFS ENSEMBLE SPREAD AND LARGE NORMALIZED STANDARD
DEVIATIONS AMONG ECMWF ENSEMBLE MEMBERS. A WEAK LAKE RESPONSE IS
EXPECTED AFTER THIS SYSTEM PASSES...BUT DELTA T VALUES SHOULD REMAIN
LESS THAN 10. OTHERWISE...KEPT TEMPERATURES COLD THROUGH WEDNESDAY.
TEMPS SHOULD RISE ABOVE NORMAL THURSDAY AS AN UPPER LEVEL RIDGE
BUILDS OVER THE REGION. GFS MEAN ENSEMBLE MEX MOS TEMPS APPEAR ON
TRACK.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST SUNDAY FOR LMZ043-046.
&&
$$
SHORT TERM...MARSILI
LONG TERM...SKIPPER
AVIATION...MARSILI
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
444 AM EST FRI MAR 1 2013
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
RELATIVELY QUIET PERIOD IN STORE FOR THE UPCOMING WEEKEND WITH MAIN
SHORT TERM FOCUS ON LINGERING LIGHT PRECIP THIS MORNING...AND
TEMPERATURE TRENDS.
WATER VAPOR IMAGERY/07Z RAP ANALYSIS SUGGEST WEAK UPPER VORT MAX
DROPPING SOUTHWARD ACROSS NORTHERN INDIANA THIS MORNING. HAVE NOTED
SOME UPSWING OVER PAST HOUR ACROSS CENTRAL/SOUTHERN SECTIONS OF
FORECAST AREA OF SOME -FZDZ PER RADAR/SFC OBSERVATIONS BUT FZDZ IS
EXPECTED TO REMAIN LIGHT ENOUGH TO PREVENT SIGNIFICANT IMPACTS THIS
MORNING. WITH AXIS OF WEAK DPVA SHIFTING ACROSS SOUTHERN/CENTRAL
AREAS WILL CONFINE EARLY MORNING FZDZ MENTION TO THESE LOCATIONS
WITH MAINLY DRY CONDITIONS ACROSS THE NORTH WERE LOW LEVEL DRY AIR
ADVECTION HAS BECOME MORE PRONOUNCED IN THE WAKE OF ASSOCIATED WEAK
INVERTED SFC TROUGH FEATURE. MARINE OBS SUGGEST SOME AUGMENTATION TO
SYNOPTIC CONVERGENCE ASSOCIATED WITH THIS TROUGH WITH WEAK LAKE
INDUCED THERMAL TROUGHING. THIS MAY ACT TO PERPETUATE SOME FLURRIES
ACROSS EXTREME NORTHWEST SECTIONS OF THE FORECAST AREA
TODAY...ALTHOUGH INCREASINGLY DRY LOW LEVEL AIR MASS SHOULD LIMIT
FLURRY/LIGHT SNOW SHOWER ACTIVITY. LIMITED DIURNAL MOVEMENT IN
TEMPERATURES EXPECTED AGAIN TODAY WITH RELATIVELY WEAK THERMAL
ADVECTION AND PERSISTENCE OF LOW CLOUD DECK.
FOR TONIGHT INTO SATURDAY...LONGWAVE RIDING ACROSS WESTERN CONUS
WILL BEGIN TO SHIFT EASTWARD AS WEAK UPPER PV ANOMALY ACROSS
NORTHERN PLAINS ADVANCES INTO THE WESTERN GREAT LAKES REGION. UPPER
FORCING/DYNAMICS LOOK TO BE QUITE WEAK WITH THIS SHORT WAVE HOWEVER
AS PV ANOMALY BECOMES AFFECTED BY MID/UPPER LEVEL DEFORMATION FLOW
ACROSS GREAT LAKES REGION. PASSAGE OF THIS FEATURE MAY MARK A SUBTLE
UPSWING IN WEAK LAKE RESPONSE IN THE FORM OF SCT FLURRIES/LIGHT SNOW
SHOWERS SATURDAY/SATURDAY NIGHT. LAKE EFFECT PARAMETERS QUITE MEAGER
HOWEVER WITH VERY DRY MID LEVEL AIR IN PLACE...AND MARGINAL LAKE/850
HPA DELTA TEMPS. DESPITE SOME WEAK REINFORCING LOW LEVEL CAA WITH
AFOREMENTIONED NORTHERN PLAINS SHORT WAVE SATURDAY...HIGH TEMPS
SHOULD BE SIMILAR TO THAT OF FRIDAY WITH THE POSSIBILITY OF A BIT
MORE INSOLATION OFFSETTING SLIGHTLY COOLER LOW LEVEL THERMAL
PROFILES.
&&
.LONG TERM...
SUNDAY THROUGH THURSDAY...THE MAIN CHALLENGE THIS PERIOD IS THE
TIMING AND TRACK OF A SHORT WAVE THAT WILL TOP THE UPSTREAM RIDGE
AND MOVE INTO THE MIDWEST NEXT WEEK. THE ECMWF APPEARS TO HAVE
INITIALIZED THIS SYSTEM REASONABLY WELL AND HAS ALSO SHOWN SOME RUN
TO RUN CONSISTENCY. FOR THIS PACKAGE...BLENDED SEVERAL MODELS
INCLUDING THE ECMWF OPERATIONAL RUN...EC ENSEMBLE MEAN...AND GFS
OPERATIONAL RUN WITH ENSEMBLE MEMBERS. GIVEN THE HIGH LATITUDE
STRONG POSITIVE ANOMALY...CONCERN THAT THESE MODELS MAY BE TOO FAST
WITH THIS SYSTEM. THE ECMWF HAS TRENDED SLIGHTLY SLOWER WITH THIS
SYSTEM WITH AN ARRIVAL TIME OF TUESDAY/TUESDAY NIGHT. HAVE TRENDED
THE SNOW CHANCES HIGHER THESE PERIODS...BUT KEPT IN CHANCE CATEGORY
DUE TO A LARGE GFS ENSEMBLE SPREAD AND LARGE NORMALIZED STANDARD
DEVIATIONS AMONG ECMWF ENSEMBLE MEMBERS. A WEAK LAKE RESPONSE IS
EXPECTED AFTER THIS SYSTEM PASSES...BUT DELTA T VALUES SHOULD REMAIN
LESS THAN 10. OTHERWISE...KEPT TEMPERATURES COLD THROUGH WEDNESDAY.
TEMPS SHOULD RISE ABOVE NORMAL THURSDAY AS AN UPPER LEVEL RIDGE
BUILDS OVER THE REGION. GFS MEAN ENSEMBLE MEX MOS TEMPS APPEAR ON
TRACK.
&&
.AVIATION...
06Z TAFS...A WEAK UPPER LEVEL SHORT WAVE ACROSS CENTRAL LOWER
MICHIGAN WILL CONTINUE TO GET SHEARED AS IT REACHES NORTHERN
INDIANA OVERNIGHT. THIS WEAKENING FORCING COMBINED WITH THE ONSET
OF DRY AIR ADVECTION SHOULD RESULT IN REDUCED INTENSITY OF DZ/FZDZ
OVERNIGHT. A FEW FLURRIES STILL POSSIBLE IN VICINITY OF UPPER VORT
MAX...BUT NOT EXPECTING SIGNIFICANT VSBY RESTRICTIONS. TRAPPED LOW
LEVEL MOISTURE SHOULD RESULT IN CONTINUED MVFR CIGS
OVERNIGHT...WITH IMPROVEMENT TO HIGHER END MVFR EXPECTED BY LATE
MORNING. DIURNAL TENDENCIES SHOULD RESULT IN TREND TO VFR LOW
CLOUDS BY MID AFTERNOON.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST SUNDAY FOR LMZ043-046.
&&
$$
SHORT TERM...MARSILI
LONG TERM...SKIPPER
AVIATION...MARSILI
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1254 PM EST FRI MAR 01 2013
...Updated Aviation Discussion...
.Forecast Update...
Issued at 1150 AM EST Fri Mar 1 2013
Did a quick update to adjust temps/POPs to current observations.
Also increased POPs after 21Z and through the evening hours to
likely as latest RAP model indicates some enhanced light to moderate
bands of precip developing by late afternoon or early evening.
Temps should be warm enough for an initial rain/snow mix changing
over to all snow this evening. With temps still above freezing,
think that impacts for the evening rush hour will be minimal but
will continue to monitor.
&&
.Short Term (Now - Saturday)...
Issued at 300 AM EST Fri Mar 1 2013
Broad upper trough is over the Midwest, with a quasi-stationary
center over southern Illinois. This feature is allowing some light
snow to fall over western Kentucky and southwest Indiana. Some
deeper moisture moving into south central Kentucky should still
allow additional snows to develop across the rest of that region
through daybreak. However, this snow looks light, as only a few
sites are reporting more than a trace of precip. Model soundings
indicate that the top of the saturated is right around -10C, so
there is not much room for prime dendritic growth. Thus not
expecting more than a light dusting the rest of the morning. Will
monitor webcams and radar through the day to see if any special
products need to be issued.
Later this afternoon, the upper low center should have drifted into
south central Kentucky. This shift should change the focus for
precip more to the south as well, with a sharp gradient in
precipitation from north to south across the forecast area.
Temperatures should warm into the upper 30s for most locations,
which would bring more of a light rain/snow mix and no further
accumulations. It should be noted that guidance tries to bring
temperatures into the 40s today, but continue to undercut that
guidance due to cloud cover and precipitation.
Tonight the upper low wobbles south into eastern Tennessee, which
should continue to drag the best precip chances southward. We should
switch back to all snow by sunset, bringing another light dusting
across the southern half of the forecast area, a half inch or less.
Will keep only a slight chance for further snow during the day
Saturday across the KY/TN border, as the upper low center weakens
and accelerates eastward. A strengthening north wind and continued
cloud cover will bring temperatures likely a couple of degrees
cooler than today, making for a raw Saturday.
.Long Term (Saturday Night through Thursday)...
Issued at 320 AM EST Fri Mar 01 2013
The beginning of the long term period will feature a broad trough
across the eastern CONUS, with an expansive ridge across the Rocky
Mountains. The flow will flatten and become more progressive by
early next week, as a strong shortwave drops through the Northern
Plains and into the Ohio Valley. In the wake of the disturbance, an
upper ridge will build in for the end of the long term period.
Surface high pressure will slip into the Ohio Valley during the day
on Sunday, which may finally allow for a few peaks of sunshine and
an end to the gloomy weather pattern we`ve been stuck in! However,
this high will quickly slide east by early Monday as the next system
takes aim on the region.
Quite a bit of uncertainty still exists for the strong system set to
impact the region Monday night into Tuesday. Guidance is really
struggling with the placement of the synoptic wave, which has large
implications on surface features and thermodynamic profiles.
Interestingly, the NAO index has been largely overforecasted
(forecasted to be much more negative than it actually is) by MRF
ensemble guidance the past several days. This could have
implications on the track of this approaching wave, as the
persistent east coast trough may break down a bit quicker than
guidance has advertised, which would suggest a more northern track
and less snow potential.
To break down the guidance, it looks as if the 01/00Z GFS is the
furthest south with the synoptic wave. Oddly enough though, it has
warmer low-level thermal profiles than the 01/00Z ECMWF. The 01/00Z
ECMWF is much more bullish in the strength of the shortwave trough,
so despite it`s more northern track, it wraps cooler air into the
system which keeps surface temperatures cooler. The 01/00Z GEM has
a similar track to the 01/00Z ECMWF, but is warmer with its thermal
profiles. Have decided to trend a bit warmer with this forecast
package, favoring the 01/00Z GEM northern track and warmer
profiles. There will most likely be some flakes mixed in,
especially across southern Indiana and north central Kentucky, but
at this point am not all too impressed with significant accumulation
chances. Obviously, still plenty of time to iron out the specific
details, so stay tuned to upcoming forecasts as things could
certainly change.
Otherwise, the shortwave quickly passes through the region, with
upper level ridging building into the Ohio Valley in its wake on
Wednesday. For you spring lovers (me included!), it looks like
things will finally warm up by the end of next week to near normal
values, with highs approaching 50 degrees on Thursday.
&&
.Aviation (18Z TAF Issuance)...
Issued at 1250 PM EST Fri Mar 1 2013
An upper level trough slowly sagging south through the area will
continue to provide light precip throughout the TAF period. For the
rest of this afternoon, expect light on and off -RASN. By late this
afternoon/early evening, short range high res models indicate an
increase in banded precip activity. While this might be -RASN at
onset, it is expected to transition to all snow this evening with
light brief accumulations possible. With sfc temps remaining above
freezing this evening, don`t expect it to cause slick spots on
runways but do expect reduced vsbys/cigs to IFR conditions.
Although most of the widespread snow shower activity should decline
after 3-4Z, flight conditions will likely stay in the IFR cat due to
cigs through much of the night. A sfc trough is expected to move
south through the area tonight shifting winds from NW to N and
causing flight conditions to improve to MVFR. This looks to happen
around 9Z at SDF/LEX and 13Z at BWG respectively.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........AMS
Short Term.......RJS
Long Term........KD
Aviation.........AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1150 AM EST FRI MAR 01 2013
.Forecast Update...
Issued at 1150 AM EST Fri Mar 1 2013
Did a quick update to adjust temps/POPs to current observations.
Also increased POPs after 21Z and through the evening hours to
likely as latest RAP model indicates some enhanced light to moderate
bands of precip developing by late afternoon or early evening.
Temps should be warm enough for an initial rain/snow mix changing
over to all snow this evening. With temps still above freezing,
think that impacts for the evening rush hour will be minimal but
will continue to monitor.
&&
.Short Term (Now - Saturday)...
Issued at 300 AM EST Fri Mar 1 2013
Broad upper trough is over the Midwest, with a quasi-stationary
center over southern Illinois. This feature is allowing some light
snow to fall over western Kentucky and southwest Indiana. Some
deeper moisture moving into south central Kentucky should still
allow additional snows to develop across the rest of that region
through daybreak. However, this snow looks light, as only a few
sites are reporting more than a trace of precip. Model soundings
indicate that the top of the saturated is right around -10C, so
there is not much room for prime dendritic growth. Thus not
expecting more than a light dusting the rest of the morning. Will
monitor webcams and radar through the day to see if any special
products need to be issued.
Later this afternoon, the upper low center should have drifted into
south central Kentucky. This shift should change the focus for
precip more to the south as well, with a sharp gradient in
precipitation from north to south across the forecast area.
Temperatures should warm into the upper 30s for most locations,
which would bring more of a light rain/snow mix and no further
accumulations. It should be noted that guidance tries to bring
temperatures into the 40s today, but continue to undercut that
guidance due to cloud cover and precipitation.
Tonight the upper low wobbles south into eastern Tennessee, which
should continue to drag the best precip chances southward. We should
switch back to all snow by sunset, bringing another light dusting
across the southern half of the forecast area, a half inch or less.
Will keep only a slight chance for further snow during the day
Saturday across the KY/TN border, as the upper low center weakens
and accelerates eastward. A strengthening north wind and continued
cloud cover will bring temperatures likely a couple of degrees
cooler than today, making for a raw Saturday.
.Long Term (Saturday Night through Thursday)...
Issued at 320 AM EST Fri Mar 01 2013
The beginning of the long term period will feature a broad trough
across the eastern CONUS, with an expansive ridge across the Rocky
Mountains. The flow will flatten and become more progressive by
early next week, as a strong shortwave drops through the Northern
Plains and into the Ohio Valley. In the wake of the disturbance, an
upper ridge will build in for the end of the long term period.
Surface high pressure will slip into the Ohio Valley during the day
on Sunday, which may finally allow for a few peaks of sunshine and
an end to the gloomy weather pattern we`ve been stuck in! However,
this high will quickly slide east by early Monday as the next system
takes aim on the region.
Quite a bit of uncertainty still exists for the strong system set to
impact the region Monday night into Tuesday. Guidance is really
struggling with the placement of the synoptic wave, which has large
implications on surface features and thermodynamic profiles.
Interestingly, the NAO index has been largely overforecasted
(forecasted to be much more negative than it actually is) by MRF
ensemble guidance the past several days. This could have
implications on the track of this approaching wave, as the
persistent east coast trough may break down a bit quicker than
guidance has advertised, which would suggest a more northern track
and less snow potential.
To break down the guidance, it looks as if the 01/00Z GFS is the
furthest south with the synoptic wave. Oddly enough though, it has
warmer low-level thermal profiles than the 01/00Z ECMWF. The 01/00Z
ECMWF is much more bullish in the strength of the shortwave trough,
so despite it`s more northern track, it wraps cooler air into the
system which keeps surface temperatures cooler. The 01/00Z GEM has
a similar track to the 01/00Z ECMWF, but is warmer with its thermal
profiles. Have decided to trend a bit warmer with this forecast
package, favoring the 01/00Z GEM northern track and warmer
profiles. There will most likely be some flakes mixed in,
especially across southern Indiana and north central Kentucky, but
at this point am not all too impressed with significant accumulation
chances. Obviously, still plenty of time to iron out the specific
details, so stay tuned to upcoming forecasts as things could
certainly change.
Otherwise, the shortwave quickly passes through the region, with
upper level ridging building into the Ohio Valley in its wake on
Wednesday. For you spring lovers (me included!), it looks like
things will finally warm up by the end of next week to near normal
values, with highs approaching 50 degrees on Thursday.
&&
.Aviation (12Z TAF Issuance)...
Issued at 610 AM EST Fri Mar 1 2013
Upper level low has drifted into western Kentucky early this
morning, and this low will continue drifting east through the day.
An east-west oriented band of mid/upper level clouds has developed
ahead of this feature across central Kentucky, and these clouds will
help to bring heavier snows just in between the TAF sites this
morning. Should continue to see high end IFR/low end MVFR cigs most
of the day, as the presence of the upper low should prevent
clearing. Cigs may raise a little by mid/late afternoon before
returning again to current levels this evening. The chance for snow
showers overnight should be limited to KBWG, as the upper low veers
southeast into eastern Tennessee.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........AMS
Short Term.......RJS
Long Term........KD
Aviation.........RJS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
616 PM EST SAT MAR 2 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 400 PM EST SAT MAR 2 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OVER THE WRN CONUS AND
AND TROUGHING OVER THE EAST...RESULTING IN NW MID/UPPER LEVEL FLOW
FROM WRN CANADA THROUGH THE PLAINS INTO THE LOWER MS VALLEY. AT THE
SFC...A RIDGE EXTENDED FROM HUDSON BAY AN NW ONTARIO THROUGH WRN
LAKE SUPERIOR. DAYTIME MIXING AND LOW LEVEL DRYING UPSTREAM
(DEWPOINT DEPRESSIONS AOA 30F) HAS SUBSTANTIALLY REDUCED THE
COVERAGE/INTENSITY OF LES INTO N CNTRL UPPER MI THIS AFTERNOON.
TONIGHT...A WEAK SHORTWAVE TROUGH TO NEAR INL WILL DIVE SE
REINFORCING THE MID LEVEL TROUGH OVER THE NRN GREAT LAKES.
HOWEVER..THE SFC RIDGE EXTENDING SOUTH FROM THE HUDSON BAY HIGH WILL
CONTINUE TO BE THE DOMINANT FEATURE OVER THE AREA. INVERSION HEIGHTS
BETWEEN 2K TO 3K FT AND THE VERY DRY AIR UPSTREAM NORTH OF LAKE
SUPERIOR...WILL HELP SUPPRESS LAKE EFFECT SNOW CHANCES/INTENSITY
DESPITE TEMPS FCST NEAR -14C AT THE BASE OF THE INVERSION.
AS LAND BREEZES DEVELOP TONIGHT...INCREASING LOW LEVEL CONVERGENCE
SHOULD STRENGTHEN LES WITH SCT -SHSN INTO NORTH CENTRAL UPPER MI FROM
MARQUETTE TO MUNISING. ANY SNOWFALL AMOUNTS...HOWEVER SHOULD BE
LIGHT AMOUNTS OF A HALF INCH OR LESS. LAKE CLOUDS ARE EXPECTED TO
LIMIT TEMP FALL OVER CNTRL AND EAST PORTIONS OF THE CWA...BUT WITH
LIGHT/CALM WINDS AND SOME CLEARING INLAND WEST...TEMPS SHOULD DROP
INTO THE SINGLE DIGITS BLO ZERO...WITH SOME LOCALLY COLDER TEMPS
POSSIBLE.
SUNDAY...SIMILAR TO TODAY...EXPECT THAT LES IN THE MORNING MAINLY
INTO N CNTRL UPPER MI WILL DIMINISH IN THE AFTERNOON WITH THE SFC
RIDGE REMAINING OVER THE REGION. EXPECT MAX TEMPERATURES TO CLIMB
INTO THE MID AND UPPER 20S AS THE ARCTIC AIRMASS SLOWLY MODIFIES.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 400 PM EST SAT MAR 2 2013
TROUGH THAT HAS BEEN STUCK OVER THE GREAT LAKES THROUGH MOST OF THIS
PAST WEEK LOOKS TO FINALLY EASE BY MID-LATE WEEK. A MORE SIGNIFICANT
SHORTWAVE TROUGH DIGS INTO THE MEAN TROUGH MONDAY THROUGH WEDNESDAY.
BASED ON TRACK OF SHORTWAVE AND H85-H5 Q-VECTOR CONVERGENCE...MOST
OF THE SNOW FROM THAT SYSTEM WILL IMPACT MOST OF MINNESOTA THROUGH
WISCONSIN AND INTO LOWER MICHIGAN. EVEN THOUGH SFC-H85 LOWS REMAIN
WELL TO SOUTH OF UPR MICHIGAN...NORTHEAST WINDS BTWN THE LOWS AND
HIGH PRESSURE OVER HUDSON BAY AND ENOUGH LOW-LEVEL MOISTURE THROUGH
H9 ALONG WITH COLD ENOUGH TEMPS AT TOP OF INVERSION SHOULD SUPPORT
LIGHT LK EFFECT THROUGH WEDNESDAY BEFORE WINDS BECOME LIGHT AND
VARIABLE. SIMILAR TO WHAT WE HAVE SEEN LATELY THE SNOW WILL BE
AROUND BUT NOT ACCUMULATE MUCH AS INVERSION HEIGHTS REMAINING
BLO 3KFT LIMIT LK EFFECT INTENSITY AND MARGINALLY COLD AIR LIMITS
FLUXES OFF THE LAKES. INCREASING MOISTURE THROWN TO NORTH OF EARLY
WEEK LOW PRESSURE SYSTEM MAY HELP ENHANCE THE SNOW SLIGHTLY MONDAY
NIGHT AND TUESDAY IN AREAS FAVORED BY NORTHEAST WINDS. PERHAPS SOME
LIGHT SNOW ACCUMULATIONS OF A FEW INCHES MAY OCCUR DURING THAT TIME.
TEMPERATURES THROUGH WEDNESDAY WILL BE GRADUALLY WARMING...BUT STILL
ONLY INTO LOWER 30S. TRICKY FORECAST NIGHTTIME LOWS SUNDAY NIGHT AS
AREAS AWAY FROM THE CLOUDS AND SNOW SHOWERS NEAR LK SUPERIOR MAY
EASILY DROP BLO ZERO. MORE CLOUDS ON MONDAY NIGHT AND TUESDAY NIGHT
SHOULD RESULT IN READINGS STAYING MOSTLY IN THE TEENS ABOVE ZERO.
HIGH PRESSURE MOVING INTO THE AREA WEDNESDAY NIGHT WILL BEGIN TO
TURN WINDS TO THE SOUTH AND WILL FINALLY END LIGHT LK EFFECT BY
THURSDAY. BY FRIDAY...UPPER LEVEL TROUGH DEVELOPS FROM WESTERN
CONUS THROUGH NORTHERN PLAINS WHILE RIDGING MOVES ACROSS GREAT LAKES
IN WAKE OF THE EARLY WEEK SYSTEM. EXPECT LOW PRESSURE TO FORM ON
LEADING EDGE OF TROUGH OVER THE PLAINS...THOUGH THE STORM SHOULD NOT
BE TOO STRONG AS LOW-LEVEL TEMPERATURE CONTRAST PRECEEDING THE
SYSTEM IS MINIMAL. GFS AND ECMWF THEN SHOW TROUGH SPLITTING BY
FRIDAY WITH SOUTHERN STREAM PORTION CLOSING OFF OVER SOUTHWEST
CONUS WHILE NORTHERN BRANCH SHORTWAVE MOVES EAST ACROSS SOUTH
CENTRAL CANADA. NORTHERN TROUGH MOVING EAST WILL DRAG THE WEAKER LOW
PRESSURE SYSTEM AND ASSOCIATED COLD FRONT ACROSS GREAT LAKES LATER
ON FRIDAY. GFS REMAINS QUICKER WITH THIS COLD FROPA COMPARED TO
ECMWF AND GEM-NH. COULD BE SOME PRECIPITATION WITH THE SYSTEM...BUT
SINCE THE H85 LOW IS OPENING UP AND BECOMING MORE PROGRESSIVE...AND
MOVING THROUGH QUICKLY...DO NOT EXPECT SIGNIFICANT PRECIPITATION.
HAVING SMALL CHANCE POPS IN THERE FOR THURSDAY NIGHT THROUGH FRIDAY
NIGHT SEEM JUSTIFIED DURING THIS TIME FRAME.
AFTER THE PERSISTENT TROUGHING KEEPS TEMPS ON THE COOLER SIDE OF
AVERAGE TO START THE WEEK...EXPECT WARMER READINGS THURSDAY INTO
FRIDAY WITH SOUTH-SOUTHWEST WINDS BTWN THE HIGH PRESSURE AND THE LOW
PRESSURE SYSTEM TO THE WEST. BASED ON 925-900MB TEMPS...SHOULD SEE
HIGHS ON THURSDAY REACH THE 30S WITH JUST A SMALL DROP IN READINGS
ON THURSDAY NIGHT IN WARM AIR ADVECTION AHEAD OF THE COLD FRONT.
TEMPERATURES ON FRIDAY PROBABLY REACH WELL INTO THE 30S. IF NOT FOR
A MOSTLY CLOUDY SKY...COULD EVEN SEE A FEW LOW-MID 40S WHERE MIXING
IS STRONGER. DID TWEAK TEMPS UPWARD NEAR LK SUPERIOR WITH DOWNSLOPE
WINDS FCST. TIGHTER PRESSURE GRADIENT WILL LEAD TO BREEZY CONDITIONS
THURSDAY NIGHT AND FRIDAY. TURNING BLUSTERY FOR SATURDAY FOLLOWING
THE COLD FRONT PASSAGE. TEMPS WILL NOT DROP TOO MUCH THOUGH...MAINLY
STAYING IN THE LOW-MID 30S...WHICH IS NEAR NORMAL FOR EARLY MARCH.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 616 PM EST SAT MAR 2 2013
DIFFICULT FORECAST CONTINUES WITH OFF AND ON AGAIN LAKE EFFECT
CLOUDS WITH NORTHERLY UPSLOPE DIRECTION CONTINUING. EACH
DAY...DIURNAL HEATING HAS MIXED OUT THE MVFR DECK WITH SOME DRIER
AIR. PERSISTENCE WITH THIS THEME WILL CONTINUE AT SAW AND CMX. VFR
CONDITIONS THIS EVENING WILL BE REPLACED WITH THE MVFR CLOUDS LATE
TONIGHT AND THIS WILL LAST INTO SUN AFTERNOON BEFORE HEATING AND
MIXING AGAIN MIXES THIS LOW DECK BACK OUT. VFR CONDITIONS WILL
CONTINUE AT IWD THROUGH THE PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 400 PM EST SAT MAR 2 2013
WINDS LESS THAN 20 KTS THROUGH MONDAY...THEN EXPECT NORTHEAST WINDS
TO INCREASE TO 30 KTS OVER WESTERN SECTIONS BY MONDAY NIGHT AS LOW
PRESSURE SYSTEM MOVES BY TO THE SOUTH OVER THE NORTHERN MISSISSIPPI
RIVER VALLEY. WINDS 20-30 KTS CONTINUE OVER MOST OF LK SUPERIOR
THROUGH TUESDAY BEFORE SETTLING DOWN TO LESS 20 KTS BY WEDNESDAY.
WINDS INCREASE TO 25 KTS FROM THE SOUTH THURSDAY NIGHT AND FRIDAY
AHEAD OF COLD FRONT. NO GALES ARE EXPECTED THIS WEEK...THOUGH COULD
SEE GALE GUSTS OVER WESTERN LK SUPERIOR MONDAY NIGHT CLOSER TO
MINNESOTA SHORELINE DUE TO COASTAL CONVERGENCE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...07
MARINE...JLA
AREA FORECAST DISCUSSION
NWS DULUTH MN
1116 AM CST FRI MAR 1 2013
.UPDATE...CLOUDS AND FLURRIES/SNOW SHOWERS CONTINUED ACROSS THE
HEAD OF THE LAKES AND ACROSS THE SOUTH SHORE OF LAKE SUPERIOR.
WILL LIKELY BE SOME FLURRIES/SNOW SHOWERS LINGERING INTO THE
AFTERNOON BUT CLOUDS WILL SLOWLY DECREASE THROUGHOUT THE DAY.
STILL A FAIR AMOUNT OF SUNSHINE IN THE NORTH. OTHERWISE ZONES AND
GRIDS IN GOOD SHAPE FOR THE AFTERNOON WITH LITTLE CHANGE.
&&
.PREV DISCUSSION... /ISSUED 610 AM CST FRI MAR 1 2013/
UPDATE...HAVE ADDED A MENTION OF FLURRIES TO THE HEAD OF LAKE
SUPERIOR INCLUDING THE TWIN PORTS FOR EARLY THIS MORNING. REST OF
THE FORECAST UNCHANGED.
PREV DISCUSSION... /ISSUED 544 AM CST FRI MAR 1 2013/
AVIATION...12Z TAFS
MVFR CEILINGS REMAINED FROM ABOUT KTWM INTO THE KBRD AREA...AND
COVERED ALL AREAS TO THE SOUTHEAST INCLUDING NORTHWEST WISCONSIN.
EAST NORTHEAST WINDS WILL CONTINUE TO GENERATE CLOUDS
TODAY AROUND LAKE SUPERIOR...ALTHOUGH WE DO THINK THEY WILL DISSIPATE
SOME FROM THE NORTH. DRIER AIR IS FORECAST TO MOVE OVER LAKE
SUPERIOR...AND THAT SHOULD HELP DISSIPATE SOME OF THE
CLOUDS...PARTICULARLY OVER KDLH. THE CEILINGS AT KBRD SHOULD ALSO
DIMINISH THROUGH THE DAY. THE RAP DOES SUGGEST MORE MVFR CEILINGS
MAY DEVELOP THIS AFTERNOON...SO WE INCLUDED A TEMPO GROUP AT
KBRD/KHIB. SOME FLURRIES WILL ALSO OCCUR UNDER SOME OF THESE
CLOUDS.
PREV DISCUSSION... /ISSUED 244 AM CST FRI MAR 1 2013/
SHORT TERM...LITTLE CHANGE TO THE PRESSURE PATTERN FROM 24 HOURS
AGO. THE TROF REMAINS STUCK NEAR THE RED RIVER VALLEY WITH THE
RIDGE AXIS TO THE W AND THE LARGE SFC LOW NOW OFF THE E
COAST...BUT CIRCULATION OVER THE FA REMAINS THE SAME. THE
DIFFERENCE IS CLOUD COVER WITH CI AND A FEW MID CLOUDS OVER THE MN
FA AND LOW CLOUDS OVER NW WI TO NEAR THE TWIN PORTS. THE SFC TROF
WILL EVENTUALLY BREAK DOWN TODAY AS THE SFC RIDGE MOVES E AND OVER
THE FA BY 00Z SATURDAY. WILL TAKE AWHILE FOR THE CLOUDS TO ERODE
AS THE RIDGE SLOWLY MOVES OVERHEAD. EVEN WITH THE NE FLOW
CONTINUING OVER LAKE SUPERIOR...AIR MASS IS TOO DRY FOR ANY LES TO
FORM AND HAVE REMOVED THE MENTION OF FLURRIES.
THE SFC RIDGE AXIS REMAINS NEARLY STATIONARY OVER THE FA THROUGH
SATURDAY. WITH A NLY FLOW ALOFT AND 850MB TEMPS AROUND -12C...MIN
TEMPS TONIGHT WILL DROP BELOW ZERO OVER THE NORTHERN HALF OF THE FA.
PLENTY OF SUN ON SATURDAY WILL NOT BE ENOUGH TO COUNTERACT THE COLD
AIR ALOFT AND MAX TEMPS WILL BE IN THE 20S WITH SOME SPOTS REACHING
30F.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
SEVERAL CONCERNS EXIST THROUGH THE PERIOD...NAMELY CHANCES FOR LAKE
EFFECT SNOW AND THE TRACK OF A STRONGER LOW PRESSURE SYSTEM THAT
COULD IMPACT THE NORTHLAND AS EARLY AS SUNDAY NIGHT...BUT MORE SO
MONDAY INTO MONDAY NIGHT.
THE MODELS ARE NOT IN REAL GOOD AGREEMENT THROUGH THE EXTENDED
PERIOD...WITH BOTH RUN TO RUN AND MODEL TO MODEL VARIABILITY.
EARLY IN THE PERIOD AN UPPER LEVEL TROUGH WILL EXTEND OVER LAKE
SUPERIOR INTO MICHIGAN...WITH THE STRONGER SHORTWAVE OVER THE
NORTHWEST CONUS/BC AREA. LOW LEVEL FLOW WILL BECOME SOUTHEAST
SATURDAY NIGHT...AND AN AREA OF LOW LEVEL WAA WILL APPROACH THE CWA
FROM THE WEST. THERE WILL BE A CHANCE FOR LIGHT SNOW WITH THE WAA
SATURDAY NIGHT OVER MUCH OF THE CWA...BUT AMOUNTS WILL BE LIGHT. WE
ADDED/INCREASED POPS ALONG THE NORTH SHORE SATURDAY NIGHT INTO
SUNDAY DUE TO A LONG FETCH WITH MARGINAL DELTA-T/S. THE AIR MASS DOES
NOT LOOK AS DRY AS EARLIER RUNS...AND GIVEN LONG FETCH AND SOME
SYNOPTIC LIFT...SOME LES CAN`T BE RULED OUT.
EMPHASIS SHIFTS TO THE APPROACHING STORM FOR SUNDAY NIGHT INTO
TUESDAY. THERE HAS BEEN A GENERAL SHIFT NORTH WITH THE EXPECTED
TRACK OF THE SYSTEM. THE GEM/NAM ARE QUITE A BIT FARTHER
NORTH...WITH THE GFS NOW THE MOST SOUTHERLY. HOWEVER...SEVERAL OF
THE GFS ENSEMBLE MEMBERS DO SHOW THE LOW/PRECIP QUITE A BIT FURTHER
NORTH THAN THE OPERATIONAL RUN. PICKING ONE PARTICULAR SOLUTION AT
THIS TIME IS JUST TOO DIFFICULT. WE DID INCREASE POPS SUNDAY NIGHT
INTO MONDAY...MAINLY ACROSS OUR SOUTHERN CWA.
THERE WILL BE A CHANCE FOR SOME LAKE EFFECT SNOW FROM ABOUT SILVER
BAY TO THE TWIN PORTS...AND ALONG THE SOUTH SHORE SUNDAY NIGHT INTO
TUESDAY. 850MB TEMPS WILL REMAIN FROM -10C TO -12C...WITH A PRETTY
GOOD FETCH. MOISTURE WILL BE AN ISSUE DEPENDING ON THE TRACK OF THE
LOW.
HOPEFULLY WE`LL SEE BETTER AGREEMENT WITH THE MODEL RUNS TODAY AND
INTO THE WEEKEND...AND WE CAN ADJUST THE FORECAST FROM THERE.
&&
.POINT TEMPS/POPS...
DLH 26 2 28 13 / 10 0 10 30
INL 23 -9 30 10 / 0 0 20 30
BRD 29 4 30 16 / 0 0 20 20
HYR 27 -1 28 0 / 0 0 10 10
ASX 25 6 28 5 / 0 0 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...DAP
LONG TERM....GROCHOCINSKI
AREA FORECAST DISCUSSION
NWS DULUTH MN
610 AM CST FRI MAR 1 2013
.UPDATE...HAVE ADDED A MENTION OF FLURRIES TO THE HEAD OF LAKE
SUPERIOR INCLUDING THE TWIN PORTS FOR EARLY THIS MORNING. REST OF
THE FORECAST UNCHANGED.
&&
.PREV DISCUSSION... /ISSUED 544 AM CST FRI MAR 1 2013/
AVIATION...12Z TAFS
MVFR CEILINGS REMAINED FROM ABOUT KTWM INTO THE KBRD AREA...AND
COVERED ALL AREAS TO THE SOUTHEAST INCLUDING NORTHWEST WISCONSIN.
EAST NORTHEAST WINDS WILL CONTINUE TO GENERATE CLOUDS
TODAY AROUND LAKE SUPERIOR...ALTHOUGH WE DO THINK THEY WILL DISSIPATE
SOME FROM THE NORTH. DRIER AIR IS FORECAST TO MOVE OVER LAKE
SUPERIOR...AND THAT SHOULD HELP DISSIPATE SOME OF THE
CLOUDS...PARTICULARLY OVER KDLH. THE CEILINGS AT KBRD SHOULD ALSO
DIMINISH THROUGH THE DAY. THE RAP DOES SUGGEST MORE MVFR CEILINGS
MAY DEVELOP THIS AFTERNOON...SO WE INCLUDED A TEMPO GROUP AT
KBRD/KHIB. SOME FLURRIES WILL ALSO OCCUR UNDER SOME OF THESE
CLOUDS.
PREV DISCUSSION... /ISSUED 244 AM CST FRI MAR 1 2013/
SHORT TERM...LITTLE CHANGE TO THE PRESSURE PATTERN FROM 24 HOURS
AGO. THE TROF REMAINS STUCK NEAR THE RED RIVER VALLEY WITH THE
RIDGE AXIS TO THE W AND THE LARGE SFC LOW NOW OFF THE E
COAST...BUT CIRCULATION OVER THE FA REMAINS THE SAME. THE
DIFFERENCE IS CLOUD COVER WITH CI AND A FEW MID CLOUDS OVER THE MN
FA AND LOW CLOUDS OVER NW WI TO NEAR THE TWIN PORTS. THE SFC TROF
WILL EVENTUALLY BREAK DOWN TODAY AS THE SFC RIDGE MOVES E AND OVER
THE FA BY 00Z SATURDAY. WILL TAKE AWHILE FOR THE CLOUDS TO ERODE
AS THE RIDGE SLOWLY MOVES OVERHEAD. EVEN WITH THE NE FLOW
CONTINUING OVER LAKE SUPERIOR...AIR MASS IS TOO DRY FOR ANY LES TO
FORM AND HAVE REMOVED THE MENTION OF FLURRIES.
THE SFC RIDGE AXIS REMAINS NEARLY STATIONARY OVER THE FA THROUGH
SATURDAY. WITH A NLY FLOW ALOFT AND 850MB TEMPS AROUND -12C...MIN
TEMPS TONIGHT WILL DROP BELOW ZERO OVER THE NORTHERN HALF OF THE FA.
PLENTY OF SUN ON SATURDAY WILL NOT BE ENOUGH TO COUNTERACT THE COLD
AIR ALOFT AND MAX TEMPS WILL BE IN THE 20S WITH SOME SPOTS REACHING
30F.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
SEVERAL CONCERNS EXIST THROUGH THE PERIOD...NAMELY CHANCES FOR LAKE
EFFECT SNOW AND THE TRACK OF A STRONGER LOW PRESSURE SYSTEM THAT
COULD IMPACT THE NORTHLAND AS EARLY AS SUNDAY NIGHT...BUT MORE SO
MONDAY INTO MONDAY NIGHT.
THE MODELS ARE NOT IN REAL GOOD AGREEMENT THROUGH THE EXTENDED
PERIOD...WITH BOTH RUN TO RUN AND MODEL TO MODEL VARIABILITY.
EARLY IN THE PERIOD AN UPPER LEVEL TROUGH WILL EXTEND OVER LAKE
SUPERIOR INTO MICHIGAN...WITH THE STRONGER SHORTWAVE OVER THE
NORTHWEST CONUS/BC AREA. LOW LEVEL FLOW WILL BECOME SOUTHEAST
SATURDAY NIGHT...AND AN AREA OF LOW LEVEL WAA WILL APPROACH THE CWA
FROM THE WEST. THERE WILL BE A CHANCE FOR LIGHT SNOW WITH THE WAA
SATURDAY NIGHT OVER MUCH OF THE CWA...BUT AMOUNTS WILL BE LIGHT. WE
ADDED/INCREASED POPS ALONG THE NORTH SHORE SATURDAY NIGHT INTO
SUNDAY DUE TO A LONG FETCH WITH MARGINAL DELTA-T/S. THE AIR MASS DOES
NOT LOOK AS DRY AS EARLIER RUNS...AND GIVEN LONG FETCH AND SOME
SYNOPTIC LIFT...SOME LES CAN`T BE RULED OUT.
EMPHASIS SHIFTS TO THE APPROACHING STORM FOR SUNDAY NIGHT INTO
TUESDAY. THERE HAS BEEN A GENERAL SHIFT NORTH WITH THE EXPECTED
TRACK OF THE SYSTEM. THE GEM/NAM ARE QUITE A BIT FARTHER
NORTH...WITH THE GFS NOW THE MOST SOUTHERLY. HOWEVER...SEVERAL OF
THE GFS ENSEMBLE MEMBERS DO SHOW THE LOW/PRECIP QUITE A BIT FURTHER
NORTH THAN THE OPERATIONAL RUN. PICKING ONE PARTICULAR SOLUTION AT
THIS TIME IS JUST TOO DIFFICULT. WE DID INCREASE POPS SUNDAY NIGHT
INTO MONDAY...MAINLY ACROSS OUR SOUTHERN CWA.
THERE WILL BE A CHANCE FOR SOME LAKE EFFECT SNOW FROM ABOUT SILVER
BAY TO THE TWIN PORTS...AND ALONG THE SOUTH SHORE SUNDAY NIGHT INTO
TUESDAY. 850MB TEMPS WILL REMAIN FROM -10C TO -12C...WITH A PRETTY
GOOD FETCH. MOISTURE WILL BE AN ISSUE DEPENDING ON THE TRACK OF THE
LOW.
HOPEFULLY WE`LL SEE BETTER AGREEMENT WITH THE MODEL RUNS TODAY AND
INTO THE WEEKEND...AND WE CAN ADJUST THE FORECAST FROM THERE.
&&
.POINT TEMPS/POPS...
DLH 25 2 28 13 / 10 0 0 30
INL 24 -9 30 10 / 0 0 0 30
BRD 29 4 29 16 / 0 0 0 20
HYR 28 -1 29 0 / 0 0 0 10
ASX 26 6 28 5 / 0 0 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...GSF
AREA FORECAST DISCUSSION
NWS DULUTH MN
544 AM CST FRI MAR 1 2013
.AVIATION...12Z TAFS
MVFR CEILINGS REMAINED FROM ABOUT KTWM INTO THE KBRD AREA...AND
COVERED ALL AREAS TO THE SOUTHEAST INCLUDING NORTHWEST WISCONSIN.
EAST NORTHEAST WINDS WILL CONTINUE TO GENERATE CLOUDS
TODAY AROUND LAKE SUPERIOR...ALTHOUGH WE DO THINK THEY WILL DISSIPATE
SOME FROM THE NORTH. DRIER AIR IS FORECAST TO MOVE OVER LAKE
SUPERIOR...AND THAT SHOULD HELP DISSIPATE SOME OF THE
CLOUDS...PARTICULARLY OVER KDLH. THE CEILINGS AT KBRD SHOULD ALSO
DIMINISH THROUGH THE DAY. THE RAP DOES SUGGEST MORE MVFR CEILINGS
MAY DEVELOP THIS AFTERNOON...SO WE INCLUDED A TEMPO GROUP AT
KBRD/KHIB. SOME FLURRIES WILL ALSO OCCUR UNDER SOME OF THESE
CLOUDS.
&&
.PREV DISCUSSION... /ISSUED 244 AM CST FRI MAR 1 2013/
SHORT TERM...LITTLE CHANGE TO THE PRESSURE PATTERN FROM 24 HOURS
AGO. THE TROF REMAINS STUCK NEAR THE RED RIVER VALLEY WITH THE
RIDGE AXIS TO THE W AND THE LARGE SFC LOW NOW OFF THE E
COAST...BUT CIRCULATION OVER THE FA REMAINS THE SAME. THE
DIFFERENCE IS CLOUD COVER WITH CI AND A FEW MID CLOUDS OVER THE MN
FA AND LOW CLOUDS OVER NW WI TO NEAR THE TWIN PORTS. THE SFC TROF
WILL EVENTUALLY BREAK DOWN TODAY AS THE SFC RIDGE MOVES E AND OVER
THE FA BY 00Z SATURDAY. WILL TAKE AWHILE FOR THE CLOUDS TO ERODE
AS THE RIDGE SLOWLY MOVES OVERHEAD. EVEN WITH THE NE FLOW
CONTINUING OVER LAKE SUPERIOR...AIR MASS IS TOO DRY FOR ANY LES TO
FORM AND HAVE REMOVED THE MENTION OF FLURRIES.
THE SFC RIDGE AXIS REMAINS NEARLY STATIONARY OVER THE FA THROUGH
SATURDAY. WITH A NLY FLOW ALOFT AND 850MB TEMPS AROUND -12C...MIN
TEMPS TONIGHT WILL DROP BELOW ZERO OVER THE NORTHERN HALF OF THE FA.
PLENTY OF SUN ON SATURDAY WILL NOT BE ENOUGH TO COUNTERACT THE COLD
AIR ALOFT AND MAX TEMPS WILL BE IN THE 20S WITH SOME SPOTS REACHING
30F.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
SEVERAL CONCERNS EXIST THROUGH THE PERIOD...NAMELY CHANCES FOR LAKE
EFFECT SNOW AND THE TRACK OF A STRONGER LOW PRESSURE SYSTEM THAT
COULD IMPACT THE NORTHLAND AS EARLY AS SUNDAY NIGHT...BUT MORE SO
MONDAY INTO MONDAY NIGHT.
THE MODELS ARE NOT IN REAL GOOD AGREEMENT THROUGH THE EXTENDED
PERIOD...WITH BOTH RUN TO RUN AND MODEL TO MODEL VARIABILITY.
EARLY IN THE PERIOD AN UPPER LEVEL TROUGH WILL EXTEND OVER LAKE
SUPERIOR INTO MICHIGAN...WITH THE STRONGER SHORTWAVE OVER THE
NORTHWEST CONUS/BC AREA. LOW LEVEL FLOW WILL BECOME SOUTHEAST
SATURDAY NIGHT...AND AN AREA OF LOW LEVEL WAA WILL APPROACH THE CWA
FROM THE WEST. THERE WILL BE A CHANCE FOR LIGHT SNOW WITH THE WAA
SATURDAY NIGHT OVER MUCH OF THE CWA...BUT AMOUNTS WILL BE LIGHT. WE
ADDED/INCREASED POPS ALONG THE NORTH SHORE SATURDAY NIGHT INTO
SUNDAY DUE TO A LONG FETCH WITH MARGINAL DELTA-T/S. THE AIR MASS DOES
NOT LOOK AS DRY AS EARLIER RUNS...AND GIVEN LONG FETCH AND SOME
SYNOPTIC LIFT...SOME LES CAN`T BE RULED OUT.
EMPHASIS SHIFTS TO THE APPROACHING STORM FOR SUNDAY NIGHT INTO
TUESDAY. THERE HAS BEEN A GENERAL SHIFT NORTH WITH THE EXPECTED
TRACK OF THE SYSTEM. THE GEM/NAM ARE QUITE A BIT FARTHER
NORTH...WITH THE GFS NOW THE MOST SOUTHERLY. HOWEVER...SEVERAL OF
THE GFS ENSEMBLE MEMBERS DO SHOW THE LOW/PRECIP QUITE A BIT FURTHER
NORTH THAN THE OPERATIONAL RUN. PICKING ONE PARTICULAR SOLUTION AT
THIS TIME IS JUST TOO DIFFICULT. WE DID INCREASE POPS SUNDAY NIGHT
INTO MONDAY...MAINLY ACROSS OUR SOUTHERN CWA.
THERE WILL BE A CHANCE FOR SOME LAKE EFFECT SNOW FROM ABOUT SILVER
BAY TO THE TWIN PORTS...AND ALONG THE SOUTH SHORE SUNDAY NIGHT INTO
TUESDAY. 850MB TEMPS WILL REMAIN FROM -10C TO -12C...WITH A PRETTY
GOOD FETCH. MOISTURE WILL BE AN ISSUE DEPENDING ON THE TRACK OF THE
LOW.
HOPEFULLY WE`LL SEE BETTER AGREEMENT WITH THE MODEL RUNS TODAY AND
INTO THE WEEKEND...AND WE CAN ADJUST THE FORECAST FROM THERE.
&&
.POINT TEMPS/POPS...
DLH 25 2 28 13 / 0 0 0 30
INL 24 -9 30 10 / 0 0 0 30
BRD 29 4 29 16 / 0 0 0 20
HYR 28 -1 29 0 / 0 0 0 10
ASX 26 6 28 5 / 0 0 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...GSF
LONG TERM....MELDE
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS BISMARCK ND
839 PM CST SAT MAR 2 2013
.DISCUSSION...CURRENT SURFACE ANALYSIS SHOWS A STATIONARY FRONT
STRETCHED OUT FROM EASTERN MONTANA INTO SOUTHWEST NORTH DAKOTA.
PLACES LIKE BEACH...DICKINSON...AND HETTINGER...ARE IN THE WARM
SECTOR WHILE TO THE NORTH AND EAST...IT IS COOLER AND NEARLY
SATURATED AS TEMPS/DEW POINTS ARE APPROACHING EACH OTHER. PATCHY FOG IS
DEVELOPING AND HAVE ADDED THIS TO THE GRIDS FOR THE OVERNIGHT
PERIOD...MAINLY ALONG AND EAST OF THE MISSOURI RIVER BASIN.
THE LATEST RAP MODEL SPREADS SOME LIGHT PRECIPITATION INTO CENTRAL
NORTH DAKOTA BETWEEN 09Z-12Z SUNDAY. THE 00Z NAM HOLDS OFF UNTIL
15Z TO 18Z SUNDAY. REGIONAL RADAR SHOWS INCREASING REFLECTIVITYS
OVER CENTRAL MONTANA. NO GROUND TRUTH SEEN YET...BUT THE NAM SEEMS
TO HAVE THIS AREA TARGETED OVERNIGHT AND PUSHES IT TO THE WESTERN
BORDER BY 15Z SUNDAY. WILL LEAVE THE CURRENT FORECAST AS IS WHICH
MENTIONS A SLIGHT CHANCE AFTER MIDNIGHT.
&&
.AVIATION...VFR CIGS/VSBYS WILL CONTINUE THROUGH 11Z SUNDAY...THEN
DETERIORATING TO MVFR/IFR BETWEEN 11Z AND 15Z. A WINTRY MIX OF
LIGHT FREEZING RAIN IS ANTICIPATED AT KISN SUNDAY MORNING THROUGH
EARLY AFTERNOON BEFORE CHANGING OVER TO SNOW. LIGHT FREEZING RAIN
IS FORECAST TO CHANGEOVER TO RAIN AT KDIK SUNDAY MORNING. SNOW
WILL DOMINATE KMOT/KBIS AND INTO KJMS SUNDAY. SNOW INTENSITY WILL
INCREASE MID TO LATE AFTERNOON THROUGH SUNDAY NIGHT WITH LIFR
CIGS/VSBYS EXPECTED AT ALL AERODROMES.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM NOON SUNDAY TO 6 AM CST TUESDAY FOR
NDZ001>005-009>013-017>023-025-034>037-046>048-050-051.
WINTER WEATHER ADVISORY FROM NOON CST /11 AM MST/ SUNDAY TO 6 AM
CST /5 AM MST/ TUESDAY FOR NDZ031>033-041-042-045.
&&
$$
DISCUSSION/AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
326 AM CST FRI MAR 1 2013
.SHORT TERM...TODAY THROUGH SATURDAY...
THE MAIN CHALLENGE FOR THE SHORT TERM IS THE EVOLUTION OF THE
STRATUS ACROSS NORTHWEST AND CENTRAL NORTH DAKOTA TODAY...WITH
MILD TEMPERATURES HIGHLIGHTING THE SOUTHWEST AND SOUTH CENTRAL ON
SATURDAY.
AS HAS BEEN THE CASE IN MOST STRATUS EVENTS THIS WINTER...THE RAP
AND HRRR HAVE THE BEST HANDLE ON THE ONGOING STRATUS ACROSS
NORTHWEST AND CENTRAL NORTH DAKOTA THIS MORNING. GIVEN LITTLE
MIXING...WILL FOLLOW CLOSELY TO THE LATEST RAP RUNS WHICH SLOWLY
ERODE THE STRATUS...YET MAINTAIN ITS PRESENCE ACROSS CENTRAL
NORTH DAKOTA THROUGH MUCH OF THE DAY. MAINTAINED THE MENTION OF
ISOLATED FLURRIES UNDER THE STRATUS THROUGH THE MORNING...WITH
PATCHY FOG ALSO POSSIBLE THIS MORNING FOR ALL AREAS WITH STRATUS
BUILD DOWN OR VIA RADIATIONAL EFFECTS ACROSS THE CLOUD FREE
SOUTHWEST. IN REGARDS TO TEMPERATURES FOR TODAY...PREFERRED THE
BIAS CORRECTED 00 UTC ECMWF/GEM AND BIAS CORRECTED RAP WHICH HAVE
SHOWN SUPERIOR SHORT TERM TEMPERATURE VERIFICATION AND CAPTURE THE
IMPACTS OF BARE GROUND...WITH HIGHS IN THE UPPER 40S FAR
SOUTHWEST. UNDER THE STRATUS OVER THE DEEPER SNOW PACKS OF THE
NORTH CENTRAL AND JAMES RIVER VALLEY...HIGHS WILL GENERALLY RANGE
IN THE LOWER TO MID 20S.
FOR TONIGHT...A RATHER MILD OVERNIGHT IS EXPECTED SOUTHWEST WITH
LOWS ONLY DROPPING INTO THE LOWER 30S WITH THE ONSET OF RETURN FLOW.
AGAIN...THE IMPACTS OF THE SNOWPACK WILL BE NOTED FROM THE TURTLE
MOUNTAINS THROUGH THE JAMES RIVER VALLEY WITH LOWS NEAR 10 WITH A
LATER COMMENCEMENT OF RETURN FLOW TONIGHT. GIVEN THE POSSIBILITY
OF NON-DIURNAL TEMPERATURE TRENDS FOR TONIGHT...FOLLOWED THE
CONSENSUS OF THE 00 UTC DETERMINISTIC MODELS WHICH SHOULD CAPTURE
THIS PATTERN.
ONCE AGAIN...THE SUPERIOR PERFORMING BIAS CORRECTED 00 UTC
ECMWF/GEM WERE FAVORED FOR TEMPERATURES ON SATURDAY...WITH HIGHS
IN THE UPPER 50S POSSIBLE FOR THE BARE GROUND OF THE FAR SOUTHWEST
WITH GOOD MIXING AND SUNSHINE IN THE WAKE OF A SURFACE WARM FRONT
THAT WILL APPROACH THE HIGHWAY 83 CORRIDOR BY 18 UTC. WITH STRATUS
EXPECTED TO BE TRAPPED UNDER THE WARM FRONTAL INVERSION ACROSS
CENTRAL NORTH DAKOTA THROUGH MUCH OF THE DAY...HIGHS WILL ONLY
RECOVER TO THE UPPER 20S FROM THE TURTLE MOUNTAINS THROUGH THE
JAMES RIVER VALLEY. FOR THE SOUTH CENTRAL...HIGHS IN THE LOWER TO
UPPER 40S ARE EXPECTED AND ARE DEPENDENT ON HOW MUCH SUNSHINE IS
RECEIVED.
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...
THE MAIN FEATURE IN THE LONG TERM PERIOD WILL BE A STORM SYSTEM
MOVING ACROSS THE NORTHERN ROCKIES AND INTO THE PLAINS SUNDAY
THROUGH MONDAY NIGHT.
LOOKING AT THE DETERMINISTIC MODELS...THERE HAS BEEN A COMPLETE FLIP
FLOP BETWEEN THE GFS/ECMWF. THE GFS IS NOW THE OUTLIER WITH A
FARTHER SOUTH TRACK WITH THE SYSTEM WITH MORE DRY AIR TO THE NORTH.
THIS LIMITS PRECIPITATION TO THE WEST AND SOUTH CENTRAL. THE ECMWF
IS MORE IN LINE WITH THE GEM...SPREADING PRECIPITATION ACROSS ALL OF
WESTERN AND CENTRAL NORTH DAKOTA...WITH A QPF MAXIMA OVER NORTH
CENTRAL INTO EASTERN NORTH DAKOTA. THE GEM IS THE MOST CONSISTENT OF
THE THREE SPREADING A GOOD AMOUNT OF PRECIPITATION ACROSS ALL OF
WESTERN AND CENTRAL NORTH DAKOTA.
AS WE BEGIN THE LONG TERM PERIOD SATURDAY NIGHT...THE UPPER LEVEL
TROUGH IS JUST MOVING ONTO THE NORTHWEST U.S. SOUTHERN BRITISH
COLUMBIA COAST...WITH UPPER LEVEL RIDGING FROM THE NORTHERN ROCKIES
INTO THE NORTHERN PLAINS. DURING THE NIGHT THE UPPER LOW MOVES ON
SHORE AND INTO THE NORTHERN ROCKIES...RESULTING IN SURFACE LOW
PRESSURE DEVELOPING IN THE LEE OF THE NORTHERN ROCKIES. THIS SHOULD
ALLOW FOR A MILD OVERNIGHT WITH AN INCREASING SOUTHEAST SURFACE FLOW
AND AN INFLUX OF MOISTURE INTO THE NORTHERN PLAINS. OVERNIGHT LOWS
MAY REMAIN ABOVE FREEZING ACROSS THE SOUTHWEST...TRANSITIONING TO
THE TEENS OVER THE NORTHEAST CWA.
THE ECMWF IS THE MOST AGGRESSIVE IN SPREADING PRECIPITATION INTO THE
LOCAL AREA ON SUNDAY...BUT BY SUNDAY AFTERNOON ALL DETERMINISTIC
MODELS BRING PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA.
THE MAIN DIFFERENCE IS THE THERMAL PROFILES WITH THE ECMWF BEING
MUCH WARMER AND KEEPING PRECIPITATION MAINLY RAIN EXCEPT FOR THE
NORTHERN TIER COUNTIES. WITH A COLDER EAST TO NORTHEAST FLOW THE GFS
DEPICTS TEMPERATURES CONDUCIVE TO SNOW FOR ALL BUT THE FAR
SOUTHWEST. BUT WITH THE DRIER EAST FLOW...IS NOT AS AGGRESSIVE IN
SPREADING PRECIPITATION INTO EASTERN PORTIONS OF THE CWA. THESE
DIFFERENCES WILL BE A BIG FACTOR IN RESULTING HIGH TEMPERATURES ON
SUNDAY AND CONSIDERING THE DIFFERENCES...WILL STICK WITH A MODEL
BLEND.
SUNDAY NIGHT AND MONDAY WILL BE THE KEY PERIODS FOR SNOWFALL
POTENTIAL. IT APPEARS AT THIS TIME...AT LEAST A PORTION OF THE CWA
WILL RECEIVE SIGNIFICANT SNOWFALL DUE TO THE DYNAMICS OF THE UPPER
LEVEL SYSTEM AND THE RESULTING FRONTOGENETIC FORCING WITH A STRONG
THERMAL PROFILE SETTING UP. THE MAIN QUESTION IS WILL IT BE FROM THE
NORTH CENTRAL INTO EASTERN NORTH DAKOTA PER THE ECMWF...THE
SOUTHWEST QUARTER PER THE GFS...OR A BROAD SOLUTION COVERING THE
ENTIRE CWA.
TWO MAIN FACTORS ARE IN PLAY HERE FOR POSSIBLE HIGHLIGHTS. FIRST THE
MODEL DIFFERENCES AND SECOND THE TIMING OF THE EVENT. WITH THE
INCONSISTENCIES BETWEEN THE GFS/ECMWF...FEEL A LITTLE MORE TIME
WOULD BE A GOOD DECISION BEFORE THE ISSUANCE OF ANY HIGHLIGHTS. IT
LOOKS LIKE THE STRONGEST FORCING AND THIS GREATEST SNOW POTENTIAL
WILL NOT BEGIN UNTIL SUNDAY NIGHT. THIS WOULD EVEN BE ON THE FAR END
FOR A WATCH IF ISSUED THIS MORNING. THEREFORE WILL HOLD OFF ON ANY
HIGHLIGHTS AT THIS TIME.
PRECIPITATION ENDS MONDAY NIGHT AND MAINLY DRY CONDITIONS ARE
EXPECTED TUESDAY AND WEDNESDAY. THERE ARE ALSO BIG DIFFERENCES
BETWEEN THE GFS/ECMWF WITH THE NEXT SYSTEM ON THURSDAY. WILL UTILIZE
A BLEND HERE.
&&
.AVIATION...
LOW PRESSURE OVER MONTANA AND HIGH PRESSURE OVER
ONTARIO IS PRODUCING AN AREA OF LOW LEVEL CONVERGENCE ACROSS WESTERN
AND CENTRAL NORTH DAKOTA WITH IFR CEILINGS AT KBIS AND KMOT AND MVFR
CEILINGS AT KISN. MAINLY CLEAR SKIES AT KDIK AND KJMS. WITH A WEAK
SURFACE FLOW...EXPECT MVFR-IFR CONDITIONS TO PERSIST THROUGH THE
MORNING ISN...KDIK...KMOT AND KBIS. WITH MOISTURE DISSIPATING BY
THIS AFTERNOON AS SOUTHERLY FLOW INCREASES. THEN MAINLY VFR
CONDITIONS EXPECTED TONIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...AYD
LONG TERM/AVIATION...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
109 AM CST FRI MAR 1 2013
.DISCUSSION...
NO SIGNIFICANT CHANGES WERE REQUIRED WITH THIS FORECAST UPDATE AS
THE INHERITED FORECAST FOR THE REMAINDER OF THE NIGHT IS WELL ON
TRACK...AND WAS BLENDED TO THE 07 UTC OBSERVED TRENDS.
AS HAS BEEN THE CASE...THE LATEST RUNS OF THE RAP AND HRRR HAVE A
GOOD HANDLE ON THE STRATUS FIELD ACROSS MUCH OF NORTHWEST AND
CENTRAL NORTH DAKOTA. GIVEN THE LACK OF MIXING...FOLLOWED CLOSELY
TO THE LATEST RAP RUNS FOR CLOUD COVER TONIGHT THROUGH THE DAY ON
FRIDAY...WHICH HOLDS THE STRATUS ACROSS THE CENTRAL INTO THE
AFTERNOON. DO EXPECT THE CURRENT STRATUS FIELD TO CONTINUE TO
BUILD DOWN THROUGH THE NIGHT TONIGHT...WITH PATCHY FOG POSSIBLE
FOR MOST AREAS. THE MOST WIDESPREAD AND DENSE FOG IS LIKELY TO BE
ACROSS THE NORTHWEST WITH A WEAK UPSLOPE FLOW COMPONENT.
&&
.AVIATION...
HE MAIN IMPACTS TO AVIATION IS THE THREAT OF MVFR/IFR CIGS AND
VSBYS IN FOG FOR THE 06Z TAF ISSUANCE. CURRENTLY THERE IS A WEAK
SURFACE TROUGH OVER THE WESTERN DAKOTAS THAT EXTENDS NORTHWESTWARD
INTO SOUTHWESTERN SASKATCHEWAN AND NORTHERN ALBERTA. THIS TROUGH
DEFINES THE WESTERN EDGE OF A LARGE HIGH PRESSURE SYSTEM...WITH A
SWATH OF IFR/MVFR/VFR CLOUDS EXTENDING ALONG THIS BOUNDARY FROM
NORTHERN SASKATCHEWAN THROUGH CENTRAL ND TO EASTERN SD. THE MODELS
INDICATE THIS SURFACE TROUGH REMAINING NEARLY STATIONARY OVERNIGHT.
EXPECTING MVFR/IFR CIGS AT KISN/KMOT/KBIS WITH SOME MVFR VSBYS IN
LIGHT FOG. EXPECT MVFR/IFR CIGS TO EVENTUALLY EXPAND EASTWARD INTO
KJMS...AND EXPAND SOUTHWARD/SOUTHWESTWARD INTO KDIK. TIMING OF FOG
FORMATION IS PROBLEMATIC BUT HAVE DECREASED VSBYS GRADUALLY AFT
AROUND 08Z/09Z.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
AVIATION...JV
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
629 PM EST SAT MAR 2 2013
.SYNOPSIS...
A STAGNANT UPPER LEVEL LOW PRESSURE AREA OVER THE NORTHEASTERN
STATES WILL MOVE TO THE EAST OVER THE NEXT TWO DAYS. WEAK HIGH
PRESSURE WILL MOVE IN FOR LATE MONDAY AND EARLY TUESDAY. LOW
PRESSURE WILL DEVELOP IN THE HIGH PLAINS SUNDAY AND MONDAY AND
TAKE A TRACK THROUGH THE OHIO VALLEY AND MID-ATLANTIC STATES
TUESDAY NIGHT AND WEDNESDAY. THIS STORM WILL PROBABLY PASS TO THE
SOUTH OF THE STATE...BUT IT COULD BRING SOME SNOW OR RAIN TO
SOUTHERN PENNSYLVANIA IN THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A WELL-DEFINED PLUME OF DEEPER MOISTURE WAS ROTATING SWD AROUND
THE BACK SIDE OF THE VERY SLOW MOVING UPPER LOW /CENTERED NEAR
KNYC THIS EVENING/. COVERAGE AND INTENSITY OF SNOW SHOWERS HAS
BEEN INCREASING OVER THE PAST FEW HOURS...AND HAVE INCREASED POPS
ACCORDINGLY BY ABOUT 30 PERCENT ACROSS THE NRN AND WESTERN
MTNS...WHERE MANY LOCATIONS WILL SEE A FRESH COATING TO ONE INCH
OF SNOW. THIS TREND IS IN LINE WITH THE 20Z HRRR AND EARLIER
12/18Z 4 AND 12KM VERSIONS OF THE NAM.
SOME OF THE RIDGE TOPS /ESPECIALLY ACROSS THE LAURELS/ COULD SEE
UP TO 2 INCHES OF POWDERY SNOW.
MAINLY FLURRIES ARE EXPECTED ACROSS THE SCENT AND SERN
ZONES...WHILE A FEW SNOW SHOWERS WITH 2SM VSBYS COULD SPILL OFF
THE ALLEGHENIES AND MAKE IT TO THE CENTRAL MTNS AND MIDDLE SUSQ
VALLEY...GIVING A DUSTING IN SOME AREAS.
THE DISTRIBUTION OF THE LIGHT SNOW WILL LIKELY PERSIST THROUGH THE
LATE NIGHT HOURS.
OVERNIGHT LOW TEMPS WILL VARY FROM THE MID TEENS ACROSS THE
NW...TO THE MID 20S IN THE SE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
MORE OF THE SAME EXPECTED FOR SUNDAY AS UPPER LOW DEPARTS ONLY
SLOWLY TO THE NORTHEAST. CLOUDS AND SLIGHTLY COOLER THAN NORMAL
MAXES WILL PREVAIL AGAIN ON SUNDAY. CONTINUING BREEZY NW WIND AND
SMALL CHANCES FOR SNOW SHOWERS AND FLURRIES...TAPERING TO NIL PAST
THE RIDGE AND VALLEY REGION.
HIGHS WILL BE WITHIN A DEGREE OR TWO OF SATURDAY AFTERNOON
READINGS RANGING FROM THE MID 20S NORTHWEST TO AROUND 40
SOUTHEAST. PERHAPS JUST A TOUCH COOLER IN THE NW WHERE 8H TEMPS GO
DOWN ONE OR TWO DEGS C.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
PERSISTENT UPPER TROF OVER THE NORTHEASTERN UNITED STATES WILL GET
A QUICK REINFORCING SHOT OF COOLER AIR ON MONDAY BEFORE IT EXITS
TO THE NORTHEAST. LOWS SUN NIGHT WILL BE SLIGHTLY COOLER THAN THE
NIGHT BEFORE...WITH HIGHS MON JUST A FEW DEGREES HIGHER THAN SUNDAY.
TUESDAY A WEAK SFC RIDGE WILL BE IN PLACE OVER CENTRAL
PA...BRINGING QUIET WEATHER ALONG WITH WARMER TEMPERATURES.
VIGOROUS UPPER TROF WILL BE SLIDING ACROSS CENTRAL PLAINS
TUES...AND FCST TO DIVE SEWD TOWARD THE CAROLINAS...SPINNING UP A
SFC LOW OVER N CAROLINA/VIRGINA ON WED. HIGH LATITUDE BLOCKING AND
EASTWARD PROPAGATION OF SHORTWAVE ENERGY SHOULD KEEP CENTER OF
MAIN LOW TO OUR SOUTH...SLIPPING OFF THE COAST S OF DELMARVA.
SYSTEM WILL HAVE SOME PHASING ISSUES...WITH SECONDARY WEAKER SFC
LOW EDGING TOWARD W PA FROM OHIO VALLEY...BUT IMPACT TO EAST COAST
WILL BE CENTERED AROUND WED-WED NIGHT. MODELS STILL HAVE SOME
DIFFERENCES...BUT GENERALLY MORE IN LINE THAN PREVIOUS RUNS...WITH
A SOUTHERN TRACK BRINGING HEAVY SNOW TO THE VIRGINIA`S APPEARING
MOST LIKELY AT THIS TIME...WITH CONSENSUS AMONG 12Z MODELS TAKING
THE BULK OF QPF WELL SOUTH OF THE MASON DIXON LINE. AS
USUAL...EXPECT MODELS TO WAVER OVER THE NEXT SEVERAL DAYS...BUT
THE POTENTIAL EXISTS FOR SOME ACCUMULATING SNOW OR RAIN LATE
TUESDAY INTO WEDNESDAY NIGHT...BUT ALL OF THE MOST IMPORTANT
DETAILS REMAIN UNCLEAR AT THIS EARLY TIME.
BEHIND THIS SYSTEM FOR LATE WEEK INTO THE WEEKEND...MINIMAL COLD
AIR TO BE SEEN AS FLOW BECOMES WESTERLY. BY FRI...HIGHS SHOULD BE
IN THE 40S AREAWIDE...AND SEVERAL DEGREES HIGHER ON SAT WITH A
PLEASANT SPRING DAY IN STORE.
&&
.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
NW FLOW REGIME WILL REMAIN ENTRENCHED ACROSS CENTRAL PA FOR THE
NEXT 36 HOURS. ANY BREAKS IN THE CLOUDS WILL CLOSE UP THIS EVENING
AND CIGS WILL LOWER AGAIN...WITH MVFR-OCNL IFR CONDITIONS IN
PLACE ACROSS WESTERN HIGHER TERRAIN AS UPSLOPE FLOW KEEPS LOW
CLOUDS AND SCATTERED SNOW SHOWERS REMAIN LOCKED IN. CENTRAL
TERMINALS SUCH AS ALTOONA AND STATE COLLEGE WILL REMAIN IN THE
2-4KFT RANGE FOR CEILINGS. EXPECT THEM TO BE VFR MOST OF THE TIME
DURING THE REST OF THE EVE AND AGAIN SUN AFTN...BUT A FEW
FLURRIES AND 2KFT CIGS COULD DRIFT IN FM THE NW - ESP TONIGHT.
MDT/LNS WILL STAY VFR. WINDS WILL REMAIN GUSTY OUT OF THE
NORTHWEST.
OUTLOOK...
MON-TUE AM...SCATTERED SNOW SHOWERS WITH INTERMITTENT CIG/VSBY
REDUCTIONS N AND W. VFR SE.
TUE PM-WED...STORM WITH A TRACK THRU MID ATLC STATES WILL BRING
THE POSS OF LOWERED CIGS/VSBYS TO THE AREA - ESP THE SRN HALF OF
THE AREA.
WED PM-THU...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...LAMBERT
SHORT TERM...DANGELO
LONG TERM...RXR
AVIATION...DANGELO/GARTNER
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
326 PM CST FRI MAR 1 2013
.SHORT TERM...
TONIGHT AND SATURDAY...FORECAST CONFIDENCE IS MEDIUM
BAND OF LIGHT SNOW SHOWERS HAS WEAKENED TO FLURRIES FROM NEAR
MADISON TO FOND DU LAC...AND SHOULD CONTINUE TO WEAKEN THROUGH
SUNSET...AS DRIER AIR WORKS INTO THE AREA. ANY FLURRIES SHOULD
DISSIPATE ACROSS MOST OF THE REST OF THE AREA SHOULD DISSIPATE BY
EVENING AS WELL...EXCEPT FOR LIGHT LAKE EFFECT SNOW SHOWERS/FLURRIES
NEAR THE SHORELINE EAST AND SOUTHEAST OF MILWAUKEE.
MARGINAL DELTA T VALUES OF 12 TO 14 DEGREES CELSIUS...FAVORABLE
NORTH NORTHEAST FETCH...AND MODEST LOW LEVEL CONVERGENCE MOVING
TOWARD THIS AREA THIS EVENING MAY BRING THIS BAND ONSHORE. HRRR AND
LOCAL WRF 4KM MODELS TRY TO DO THIS...THEN TRY TO SHIFT IT BACK
OFFSHORE AFTER 06Z SATURDAY. LEFT SCATTERED POPS FOR LIGHT SNOW
SHOWERS SOUTH OF MILWAUKEE NEAR THE LAKE TONIGHT. A FEW TENTHS OF AN
INCH COULD FALL IF THESE BANDS MAKE IT ONSHORE. LOW LEVEL FLOW
BECOMES MORE NORTHERLY SATURDAY...WHICH SHOULD KEEP THIS BAND
OFFSHORE. LEFT FLURRIES IN THE FAR SOUTHEAST...WITH LOW LEVEL
MOISTURE LINGERING WITHIN DENDRITE ZONE.
CLOUDS SHOULD GRADUALLY MIX OUT FROM NORTHWEST TO SOUTHEAST ACROSS
THE AREA TONIGHT...AND FINALLY MIX OUT IN THE FAR SOUTHEAST COUNTIES
BY SATURDAY AFTERNOON AS LAKE EFFECT CLOUDS MOVE OFF TO THE
SOUTHEAST. TEMPERATURES WILL BE BELOW SEASONAL NORMALS TONIGHT AND
SATURDAY...WITH 10 TO 15 INLAND WITH AT LEAST PARTIAL CLEARING...AND
UPPER TEENS WITH MORE CLOUDS IN THE FAR SOUTHEAST COUNTIES NEAR THE
LAKE. HIGHS IN THE MID TO UPPER 20S SEEM REASONABLE FOR SATURDAY.
SATURDAY NIGHT THROUGH TUESDAY...FORECAST CONFIDENCE MEDIUM
SFC HIGH PRESSURE TO SETTLE OVER THE REGION SAT NT AND SUN. A
SHORTWAVE TROUGH WILL TRACK DUE SOUTH FROM CANADA TO LOWER MI FOR
THIS TIME PERIOD BUT AIRMASS REMAINS DRY. MID TO HIGH CLOUDS WILL
BE INCREASING LATE SAT NT INTO SUNDAY WITH WARM ADVECTION ALOFT
AND RIDGING. RIDGING IS IN RESPONSE TO A STRONG SHORTWAVE TROUGH
OVER MT THAT WILL MOVE TO THE MIDDLE MS RIVER VALLEY ON TUE AND TO
THE EAST COAST FOR WED. RUN TO RUN MODEL CONSISTENCY IS
STRUGGLING WITH THE EXACT TRACK OF THE STRONG SHORTWAVE
TROUGH. HOWEVER...LATEST MODELS HAVE FAIRLY GOOD AGREEMENT MINUS THE
OUTLIER OF THE NAM. WILL STILL ACCOUNT FOR THE LACK OF RUN TO RUN
CONSISTENCY HOWEVER AND FORECAST SMALL CHANCES OF LIGHT SNOW
BEGINNING LATE SUN NT OVER SOUTH CENTRAL WI AND THEN SPREADING
EAST WITH CHANCES OF LIGHT SNOW THROUGH TUE NT. EXPECT THE MAIN
AXIS OF SNOW TO REMAIN MOSTLY ACROSS IA AND IL WITH BEST CHANCES
FOR THE NRN PORTION OF THE SNOW TO AFFECT SRN WI ON TUE.
WENT WITH FAIRLY COLD TEMPS SAT NT AND SUN NT DUE TO GOOD
RADIATIONAL COOLING WITHIN A POLAR HIGH. THE CLOUDS WILL ARRIVE TOO
LATE ON SAT NT FOR MUCH EFFECT AND ONLY PTLY CLOUDY CONDITIONS
ARE FORECAST FOR SUN NT. 925 MB TEMPS SUGGEST HIGHS WILL BE AROUND
30F FOR SUN-TUE.
.LONG TERM...
WEDNESDAY THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM
RIDGING ALOFT IS EXPECTED FOR WED INTO THU AS A LONGWAVE POLAR
TROUGH MOVES INTO THE WRN USA. AT THE SFC...POLAR HIGH PRESSURE
WILL PREVAIL DURING THIS TIME BUT IT MAY MOVE EAST BY THU
AFTERNOON ALLOWING SLY WINDS TO DEVELOP WITH MILDER TEMPS. BELOW
NORMAL TEMPS ARE EXPECTED BEFOREHAND. A SHORTWAVE TROUGH AND LOW
PRESSURE AREA WILL THEN MOVE NEWD THROUGH THE NRN PLAINS AND MN
FOR THU AND THU NT WITH SLIGHT CHANCES OF LIGHT SNOW OVER SRN WI
DUE TO WARM ADVECTION. SLY WINDS WILL CONTINUE ON FRI AS THE LOW
TRACKS ENEWD ACROSS ONTARIO CANADA. THUS MILD HIGH TEMPS IN THE
40S ARE EXPECTED.
&&
.AVIATION/00Z TAFS/...
FOR MADISON AND WAUKESHA TAF SITES...EXPECT FLURRIES TO LINGER UNTIL
AROUND 00Z SATURDAY. VFR VISIBILITIES ARE EXPECTED...WITH CEILINGS
REMAINING BELOW FUEL ALTERNATE THRESHOLDS LATE THIS AFTERNOON AND
PERHAPS THROUGH EARLY THIS EVENING...BEFORE DRIER AIR MIXES OUT THE
CEILINGS LATER THIS EVENING INTO EARLY SATURDAY. GUSTY NORTH
NORTHEAST WINDS LATE THIS AFTERNOON WILL DIMINISH THIS
EVENING...WITH MODEST NORTH WINDS THROUGH SATURDAY.
FOR MILWAUKEE AND KENOSHA TAF SITES...EXPECT LIGHT LAKE EFFECT SNOW
SHOWERS/FLURRIES TO LINGER THROUGH MOST OF TONIGHT...BUT DIMINISH IN
AREAL COVERAGE. A FEW TENTHS OF AN INCH OF ACCUMULATION ARE POSSIBLE
WITH ANY PERSISTENT LIGHT SNOW BANDS...MAINLY AT KENOSHA. MAINLY VFR
VISIBILITIES EXPECTED.
CEILINGS REMAIN BELOW FUEL ALTERNATES THROUGH MOST OF
TONIGHT...BEFORE MIXING OUT BY MID TO LATE SATURDAY MORNING WITH
DRIER AIR MOVING INTO THE AREA. GUSTY NORTH WINDS LATE THIS
AFTERNOON WILL REMAIN SOMEWHAT GUSTY TONIGHT INTO EARLY
SATURDAY...REMAINING NORTHERLY ON SATURDAY.
&&
.MARINE...
SMALL CRAFT ADVISORY HAS BEEN EXTENDED UNTIL 09Z SUNDAY ACROSS THE
NEARSHORE WATERS OF LAKE MICHIGAN. TIGHT PRESSURE GRADIENT WILL
REMAIN ACROSS THIS AREA INTO SATURDAY MORNING...BEFORE GRADUALLY
RELAXING DURING THE AFTERNOON. GUSTY NORTH WINDS OF 15 TO 25 KNOTS
WITH GUSTS TO AROUND 30 KNOTS ARE EXPECTED THROUGH TONIGHT...THEN
SLOWLY DECREASE ON SATURDAY.
HIGH WAVES OF 6 TO 9 FEET THIS EVENING WILL GRADUALLY SUBSIDE
THROUGH SATURDAY NIGHT...AS WINDS REMAIN NORTH BEFORE BACKING
NORTHWEST.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 3 AM CST SUNDAY FOR LMZ643>646.
&&
$$
TONIGHT/SATURDAY AND AVIATION/MARINE...WOOD
SATURDAY NIGHT THROUGH FRIDAY...GEHRING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1130 AM CST FRI MAR 1 2013
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
308 AM CST FRI MAR 1 2013
POTENTIAL FOR ACCUMULATING SNOW SUNDAY NIGHT AND HEADING INTO THE
LONG TERM PERIOD.
CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER THE WESTERN U.S. INTO ALBERTA AND GENERAL BROAD
TROUGHING OVER THE EAST HALF OF THE U.S.. THE FORECAST AREA SITS IN
A NON-DESCRIPT FLOW WITHIN THIS BROAD TROUGH...DUE TO THE MAIN JET
FLOW CONFINED OVER THE WESTERN DAKOTAS...AND AN UPPER LOW STUCK OVER
NEW ENGLAND. THIS NON-DESCRIPT FLOW HAS RESULTED IN THE VERY SLOW
SURFACE PATTERN PROGRESSION...WITH THE AREA STILL UNDER CYCLONIC
FLOW AROUND LOW PRESSURE IN NEW ENGLAND. A TROUGH EXTENDING WEST
FROM THE LOW EXTENDS WEST NEAR I-80 TO DES MOINES...THEN TO THE
NORTHWEST TO FARGO. SLOWLY DRIER AIR IS ADVECTING SOUTHWARD INTO THE
CYCLONIC CIRCULATION FROM HIGH PRESSURE OVER HUDSON BAY...RESULTING
IN CLEARING OVER NORTHERN LAKE SUPERIOR INTO THE NORTHERN 2/3 OF
MINNESOTA. HOWEVER...THE 00Z MPX AND GRB SOUNDINGS STILL SHOW A 50MB
SATURATED LAYER STUCK AROUND A COLD FRONTAL INVERSION SITTING AT
825MB. THUS...STRATUS STILL COVERS THE AREA. THIS STRATUS COMBINED
WITH A 5-10 KT NORTHEAST WIND HAS KEPT TEMPERATURES MAINLY IN THE
20S...DESPITE 850MB TEMPS AROUND -11C OR 1 STANDARD DEVIATION BELOW
NORMAL PER 00Z RAOBS.
SHORT TERM HIGHLIGHTS / CONCERNS:
1. WHEN WILL IT CLEAR
THIS IS A TWO PART ISSUE. FIRST AND MORE IMPORTANTLY IS THE GENERAL
STRATUS DECK IN PLACE. 01.00Z NAM WAS SURPRISINGLY TOO AGGRESSIVE
WITH CLEARING...SUGGESTING BASED ON 850MB AND 900MB RH FIELDS THAT
LOCATIONS NORTH OF I-90 WOULD BE CLEAR RIGHT NOW. LATEST RAP 850MB
AND 900MB RH GUIDANCE SEEMS TO HAVE A BETTER HANDLE ON THE LOW
CLOUDS...GRADUALLY CLEARING LOCATIONS NORTH OF I-90 NORTH TO SOUTH
THROUGH 21Z. A COMBINATION OF DAYTIME MIXING AND A STRONGER SURGE OF
DRY AIR FROM NORTHERN ONTARIO APPEARS TO BE AIDING IN THIS CLEARING.
SOUTH OF I-90...THE LOW CLOUDS MAY NOT DISSIPATE UNTIL SOMETIME
DURING THE EVENING. THE SECOND PART OF THE CLEARING ISSUE IS IN THE
UPPER LEVELS WHERE SCT-BKN CIRROSTRATUS EXISTS OVER THE AREA. THE
NON-DESCRIPT UPPER LEVEL FLOW WOULD SUGGEST CLEARING OF THE CIRRUS
WILL BE PROBLEMATIC. NAM/RAP 500-400MB RH FIELD CONFIRM THIS AS WELL
WITH MUCH OF THE AREA DOMINATED BY SCT-BKN CIRROSTRATUS THROUGH THE
DAY TODAY...ESPECIALLY OVER THE WESTERN HALF. IT LOOKS LIKE WE
FINALLY CAN CLEAR THESE HIGH CLOUDS OUT TONIGHT INTO SATURDAY
MORNING AS THE UPPER RIDGE OVER THE WESTERN U.S. BEGINS PROGRESSING
EAST.
2. TEMPERATURES TODAY THROUGH SATURDAY NIGHT
THE STRONGER NOW EARLY MARCH SUN CAN DEFINITELY WARM TEMPERATURES
UP...EVEN UNDER AN ENVIRONMENT OF COLD 850MB TEMPS...LIKE THOSE
TODAY AROUND -11C. HOWEVER...WITH ONLY PARTIAL CLEARING OVERALL
NORTH OF I-90...IT LOOKS TOUGH TO GET TEMPERATURES TO OR ABOVE
FREEZING. NAM 2 METER AND MET GUIDANCE LOOKS A BIT TOO OPTIMISTIC...
GIVEN THE FACT THAT IT HAS CLEARING MUCH EARLIER THAN WHAT WILL
OCCUR. HAVE LEANED MORE TOWARDS MAV/ECMWF/GEM GUIDANCE AS A RESULT.
RELATIVELY COOL CONDITIONS TODAY COMBINED WITH CLEARING TONIGHT AND
WINDS CALMING WITH HIGH PRESSURE BUILDING IN SETS THE STAGE FOR A
DECENT RADIATIONAL COOLING NIGHT. THUS...STAYED TOWARD THE COOL END
OF GUIDANCE. MUCH MORE SUN ON SATURDAY WITH SIMILAR 850MB TEMPS WILL
YIELD JUST A SLIGHTLY WARMER DAY. THE SURFACE HIGH PRESSURE RIDGE IS
PROGGED TO REMAIN NEARBY SATURDAY NIGHT...WHICH AGAIN PUTS A GOOD
RADIATIONAL COOLING NIGHT IN FOCUS. HOWEVER...MID AND HIGH CLOUDS
LOOK TO INCREASE COMING THROUGH THE UPPER RIDGE BUILDING TOWARDS US.
THUS...WE SHOULD NOT GET AS COOL AS TONIGHT. STILL...TIMING OF THE
CLOUDS IS EVERYTHING AND TYPICAL COLD SPOTS IN WISCONSIN COULD STILL
END UP PLUMMETING. THUS...FOR THE TYPICAL COLD SPOTS LEANED MORE
TOWARDS THE COLDER SIDE OF GUIDANCE FOR THEM.
3. POTENTIAL FOR WARM ADVECTION PRECIPITATION SUNDAY/SUNDAY NIGHT
MODELS ARE PROGGING THAT A POTENT UPPER TROUGH...CURRENTLY PRESENT
NEAR 45 N / 150W WELL SOUTH OF THE GULF OF ALASKA...WILL CRASH
THROUGH THE UPPER RIDGING BUILDING TOWARDS THE FORECAST AREA DURING
THE WEEKEND. BY 12Z SUNDAY...GOOD MODEL AGREEMENT EXISTS THAT THIS
POTENT UPPER TROUGH...PERHAPS IN THE FORM OF A CLOSED LOW...SHOULD
BE OVER WASHINGTON STATE. THERE STILL REMAINS SOME DISAGREEMENT ON
THE TRACK OF THE POTENT UPPER TROUGH AFTERWARDS...BUT THERE DOES
APPEAR TO BE A CONVERGING SOLUTION. BY 12Z MONDAY...THE TROUGH
SHOULD EXIST SOMEWHERE BETWEEN ENTERING WESTERN SOUTH DAKOTA
/SLOWER 01.00Z ECMWF/ TO SOUTHEAST SOUTH DAKOTA /FASTER 01.00Z NAM/.
THE SPEED FACTOR APPEARS TO BE RELATED TO HOW POTENT A SHORTWAVE IS
DROPPING THROUGH MICHIGAN ON SUNDAY...THE MORE POTENT THE SLOWER THE
UPPER TROUGH COMING ACROSS THE NORTHERN ROCKIES WILL BE. THIS
FORECAST IS GOING TO TAKE A CONSENSUS APPROACH TO THE 01.00Z
GUIDANCE...GIVEN THE CONVERGING TREND BUT AT THE SAME TIME ALLOWS
FOR A LITTLE CONTINUITY.
DETAILS...AS THE POTENT TROUGH DIGS INTO THE NORTHERN ROCKIES ON
SUNDAY...LOW PRESSURE DEEPENS DOWNSTREAM OVER SOUTH DAKOTA AND
NEBRASKA. IN TURN...WARM ADVECTION INTENSIFIES...DEVELOPING A MASS
OF MID CLOUDS FROM THE DAKOTAS INTO THE FORECAST AREA. THE 00Z
GFS/UKMET/CANADIAN ALL DEVELOP SOME LIGHT PRECIP WEST OF THE
MISSISSIPPI RIVER BETWEEN 18-00Z...BUT UNSURE IF THIS IS GOING TO
REACH THE GROUND AS REFLECTED BY THE 00Z ECMWF. INCLUDED JUST A 20
PERCENT CHANCE OVER SOUTHEAST MN FOR NOW. CHANCES INCREASE
EVERYWHERE SUNDAY NIGHT...ESPECIALLY WEST OF THE MISSISSIPPI
RIVER...ASSOCIATED WITH THE TROUGH PUSHING EAST AND MORE IMPORTANTLY
THE LOW TO MID-LEVEL FRONTOGENESIS ZONE STRENGTHENING. INCREASED
CHANCES TOWARD 60 LATE IN THE NIGHT WEST OF HWY 52.
ANOTHER CONCERN TO WATCH IS A POTENTIAL WARM LAYER ACCOMPANYING THIS
SYSTEM. THE FASTEST 01.00Z NAM WOULD SUGGEST THAT THE PRECIPITATION
SUNDAY AFTERNOON OR EVENING WOULD START AS SLEET SAY IN THE AUSTIN
AREA. HOWEVER...SINCE A COMPROMISE APPROACH WAS FOLLOWED...ANY MIXED
PRECIPITATION TYPE TRANSITION ZONE SHOULD STAY OFF TO THE WEST.
.LONG TERM...MONDAY THROUGH THURSDAY NIGHT
308 AM CST FRI MAR 1 2013
MAIN CONCERN/FOCUS OF THE LONG TERM PERIOD REMAINS ON THE POTENT
UPPER TROUGH IN SOUTH DAKOTA EARLY MONDAY. THE 01.00Z
ECMWF/UKMET/CANADIAN AND GFS ENSEMBLES ARE ALL IN GOOD AGREEMENT
THAT THIS TROUGH WILL CLOSE OFF AND BE IN/NEAR WESTERN IOWA BY 12Z
TUESDAY. NOTE THAT THE 01.00Z GFS ALSO CLOSES IT OFF...BUT IS MUCH
MORE PROGRESSIVE...DOWN IN SOUTHERN MISSOURI AT 12Z TUESDAY. GIVEN
THE PREDOMINANCE OF SLOWER SOLUTIONS...DISCOUNTED THE GFS. THESE
SLOWER SOLUTIONS MEAN THAT A LOW TO MID-LEVEL FRONTOGENESIS BAND
WILL GET STUCK. WHEREVER THIS OCCURS THERE COULD END UP BEING SOME
DECENT SNOW ACCUMULATIONS. RIGHT NOW IT APPEARS THE BAND WOULD SET
UP FROM NORTH DAKOTA INTO SOUTHEAST MN AND INTO EASTERN IOWA. RAISED
PRECIPITATION CHANCES IN THIS AREA 20 PERCENT FROM THE PREVIOUS
FORECAST...AND MAY NEED TO BE RAISED MORE IF TRENDS CONTINUE.
A LONGWAVE TROUGH IS FORECAST TO TRY TO ENTER THE WEST COAST TUESDAY
NIGHT...WHICH MODELS HAVE SHOWN FOR AWHILE. THIS TROUGH WILL HELP
BUILD AND PUSH RIDGING EASTWARD...CAUSING THE UPPER LOW OVER WESTERN
IOWA TO SHIFT SOUTHEAST...AND PUSH THE LOW TO MID-LEVEL
FRONTOGENESIS CIRCULATION EASTWARD. THUS...THE SNOW MAY END UP
OVERSPREADING MUCH OF THE AREA ON TUESDAY AND ADDED 20-40 PERCENT
CHANCES AS A RESULT. EVEN ADDED A 20 PERCENT CHANCE OVER THE
SOUTHEAST 1/3 TUESDAY NIGHT.
WHEN ALL IS SAID AND DONE FROM THE SUNDAY NIGHT THROUGH TUESDAY
PERIOD...WE COULD BE LOOKING AT EITHER A LONG DURATION ADVISORY
EVENT OR EVEN WARNING IF THE 01.00Z CANADIAN ENDS UP RIGHT.
DEFINITELY NEED MODELS TO COME TO BETTER AGREEMENT AND MORE
DETAILS WORKED OUT BEFORE SPECULATING ON SNOWFALL AMOUNTS. 01.06Z
NAM CONTINUES TO SHOW AN AGGRESSIVE QPF SCENARIO SIMILAR TO THE
CANADIAN...ALONG WITH SPREADING PRECIPITATION FARTHER EAST. QUICK
LOOK AT THE 01.00Z ECMWF ENSEMBLE MEAN ALSO APPEARS TO BE IN-LINE
WITH THE NAM/CANADIAN IN TERMS OF 500MB HEIGHT AND MSLP. AS
MENTIONED...PLENTY OF DETAILS TO WORK OUT.
QUIET WEATHER ROUNDS OUT THE REST OF THE WEEK WITH MODELS IN GOOD
AGREEMENT SHIFTING THE UPPER RIDGE INTO THE FORECAST AREA. THIS
SHOULD BRING TEMPERATURES BACK UP TO NEAR OR POSSIBLY EVEN ABOVE
NORMAL BY THURSDAY. IF THE 01.00Z GFS IS CORRECT...WE COULD EVEN BE
LOOKING AT A RAIN/SNOW MIX THURSDAY NIGHT AS IT EJECTS OUT A
SHORTWAVE FROM THE WESTERN TROUGH THROUGH/NEARBY THE FORECAST AREA.
&&
.AVIATION...THROUGH 18Z SATURDAY
1130 AM CST FRI MAR 1 2013
HIGH PRESSURE WILL GRADUALLY PUSH INTO THE AREA FROM THE NORTHWEST THROUGH
THE PERIOD. THE MVFR/VFR STRATUS DECK WILL SLOWLY RISE THROUGH THE AFTERNOON
HOURS AND EVENTUALLY CLEAR OUT THIS EVENING. EXPECT THE LOWEST
CEILINGS TO RANGE FROM 025-035K KFEET THROUGH 00Z...WITH CLEAR
SKIES EXPECTED AFTER 06Z-08Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
308 AM CST FRI MAR 1 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
537 AM CST FRI MAR 1 2013
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
308 AM CST FRI MAR 1 2013
POTENTIAL FOR ACCUMULATING SNOW SUNDAY NIGHT AND HEADING INTO THE
LONG TERM PERIOD.
CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER THE WESTERN U.S. INTO ALBERTA AND GENERAL BROAD
TROUGHING OVER THE EAST HALF OF THE U.S.. THE FORECAST AREA SITS IN
A NON-DESCRIPT FLOW WITHIN THIS BROAD TROUGH...DUE TO THE MAIN JET
FLOW CONFINED OVER THE WESTERN DAKOTAS...AND AN UPPER LOW STUCK OVER
NEW ENGLAND. THIS NON-DESCRIPT FLOW HAS RESULTED IN THE VERY SLOW
SURFACE PATTERN PROGRESSION...WITH THE AREA STILL UNDER CYCLONIC
FLOW AROUND LOW PRESSURE IN NEW ENGLAND. A TROUGH EXTENDING WEST
FROM THE LOW EXTENDS WEST NEAR I-80 TO DES MOINES...THEN TO THE
NORTHWEST TO FARGO. SLOWLY DRIER AIR IS ADVECTING SOUTHWARD INTO THE
CYCLONIC CIRCULATION FROM HIGH PRESSURE OVER HUDSON BAY...RESULTING
IN CLEARING OVER NORTHERN LAKE SUPERIOR INTO THE NORTHERN 2/3 OF
MINNESOTA. HOWEVER...THE 00Z MPX AND GRB SOUNDINGS STILL SHOW A 50MB
SATURATED LAYER STUCK AROUND A COLD FRONTAL INVERSION SITTING AT
825MB. THUS...STRATUS STILL COVERS THE AREA. THIS STRATUS COMBINED
WITH A 5-10 KT NORTHEAST WIND HAS KEPT TEMPERATURES MAINLY IN THE
20S...DESPITE 850MB TEMPS AROUND -11C OR 1 STANDARD DEVIATION BELOW
NORMAL PER 00Z RAOBS.
SHORT TERM HIGHLIGHTS / CONCERNS:
1. WHEN WILL IT CLEAR
THIS IS A TWO PART ISSUE. FIRST AND MORE IMPORTANTLY IS THE GENERAL
STRATUS DECK IN PLACE. 01.00Z NAM WAS SURPRISINGLY TOO AGGRESSIVE
WITH CLEARING...SUGGESTING BASED ON 850MB AND 900MB RH FIELDS THAT
LOCATIONS NORTH OF I-90 WOULD BE CLEAR RIGHT NOW. LATEST RAP 850MB
AND 900MB RH GUIDANCE SEEMS TO HAVE A BETTER HANDLE ON THE LOW
CLOUDS...GRADUALLY CLEARING LOCATIONS NORTH OF I-90 NORTH TO SOUTH
THROUGH 21Z. A COMBINATION OF DAYTIME MIXING AND A STRONGER SURGE OF
DRY AIR FROM NORTHERN ONTARIO APPEARS TO BE AIDING IN THIS CLEARING.
SOUTH OF I-90...THE LOW CLOUDS MAY NOT DISSIPATE UNTIL SOMETIME
DURING THE EVENING. THE SECOND PART OF THE CLEARING ISSUE IS IN THE
UPPER LEVELS WHERE SCT-BKN CIRROSTRATUS EXISTS OVER THE AREA. THE
NON-DESCRIPT UPPER LEVEL FLOW WOULD SUGGEST CLEARING OF THE CIRRUS
WILL BE PROBLEMATIC. NAM/RAP 500-400MB RH FIELD CONFIRM THIS AS WELL
WITH MUCH OF THE AREA DOMINATED BY SCT-BKN CIRROSTRATUS THROUGH THE
DAY TODAY...ESPECIALLY OVER THE WESTERN HALF. IT LOOKS LIKE WE
FINALLY CAN CLEAR THESE HIGH CLOUDS OUT TONIGHT INTO SATURDAY
MORNING AS THE UPPER RIDGE OVER THE WESTERN U.S. BEGINS PROGRESSING
EAST.
2. TEMPERATURES TODAY THROUGH SATURDAY NIGHT
THE STRONGER NOW EARLY MARCH SUN CAN DEFINITELY WARM TEMPERATURES
UP...EVEN UNDER AN ENVIRONMENT OF COLD 850MB TEMPS...LIKE THOSE
TODAY AROUND -11C. HOWEVER...WITH ONLY PARTIAL CLEARING OVERALL
NORTH OF I-90...IT LOOKS TOUGH TO GET TEMPERATURES TO OR ABOVE
FREEZING. NAM 2 METER AND MET GUIDANCE LOOKS A BIT TOO OPTIMISTIC...
GIVEN THE FACT THAT IT HAS CLEARING MUCH EARLIER THAN WHAT WILL
OCCUR. HAVE LEANED MORE TOWARDS MAV/ECMWF/GEM GUIDANCE AS A RESULT.
RELATIVELY COOL CONDITIONS TODAY COMBINED WITH CLEARING TONIGHT AND
WINDS CALMING WITH HIGH PRESSURE BUILDING IN SETS THE STAGE FOR A
DECENT RADIATIONAL COOLING NIGHT. THUS...STAYED TOWARD THE COOL END
OF GUIDANCE. MUCH MORE SUN ON SATURDAY WITH SIMILAR 850MB TEMPS WILL
YIELD JUST A SLIGHTLY WARMER DAY. THE SURFACE HIGH PRESSURE RIDGE IS
PROGGED TO REMAIN NEARBY SATURDAY NIGHT...WHICH AGAIN PUTS A GOOD
RADIATIONAL COOLING NIGHT IN FOCUS. HOWEVER...MID AND HIGH CLOUDS
LOOK TO INCREASE COMING THROUGH THE UPPER RIDGE BUILDING TOWARDS US.
THUS...WE SHOULD NOT GET AS COOL AS TONIGHT. STILL...TIMING OF THE
CLOUDS IS EVERYTHING AND TYPICAL COLD SPOTS IN WISCONSIN COULD STILL
END UP PLUMMETING. THUS...FOR THE TYPICAL COLD SPOTS LEANED MORE
TOWARDS THE COLDER SIDE OF GUIDANCE FOR THEM.
3. POTENTIAL FOR WARM ADVECTION PRECIPITATION SUNDAY/SUNDAY NIGHT
MODELS ARE PROGGING THAT A POTENT UPPER TROUGH...CURRENTLY PRESENT
NEAR 45 N / 150W WELL SOUTH OF THE GULF OF ALASKA...WILL CRASH
THROUGH THE UPPER RIDGING BUILDING TOWARDS THE FORECAST AREA DURING
THE WEEKEND. BY 12Z SUNDAY...GOOD MODEL AGREEMENT EXISTS THAT THIS
POTENT UPPER TROUGH...PERHAPS IN THE FORM OF A CLOSED LOW...SHOULD
BE OVER WASHINGTON STATE. THERE STILL REMAINS SOME DISAGREEMENT ON
THE TRACK OF THE POTENT UPPER TROUGH AFTERWARDS...BUT THERE DOES
APPEAR TO BE A CONVERGING SOLUTION. BY 12Z MONDAY...THE TROUGH
SHOULD EXIST SOMEWHERE BETWEEN ENTERING WESTERN SOUTH DAKOTA
/SLOWER 01.00Z ECMWF/ TO SOUTHEAST SOUTH DAKOTA /FASTER 01.00Z NAM/.
THE SPEED FACTOR APPEARS TO BE RELATED TO HOW POTENT A SHORTWAVE IS
DROPPING THROUGH MICHIGAN ON SUNDAY...THE MORE POTENT THE SLOWER THE
UPPER TROUGH COMING ACROSS THE NORTHERN ROCKIES WILL BE. THIS
FORECAST IS GOING TO TAKE A CONSENSUS APPROACH TO THE 01.00Z
GUIDANCE...GIVEN THE CONVERGING TREND BUT AT THE SAME TIME ALLOWS
FOR A LITTLE CONTINUITY.
DETAILS...AS THE POTENT TROUGH DIGS INTO THE NORTHERN ROCKIES ON
SUNDAY...LOW PRESSURE DEEPENS DOWNSTREAM OVER SOUTH DAKOTA AND
NEBRASKA. IN TURN...WARM ADVECTION INTENSIFIES...DEVELOPING A MASS
OF MID CLOUDS FROM THE DAKOTAS INTO THE FORECAST AREA. THE 00Z
GFS/UKMET/CANADIAN ALL DEVELOP SOME LIGHT PRECIP WEST OF THE
MISSISSIPPI RIVER BETWEEN 18-00Z...BUT UNSURE IF THIS IS GOING TO
REACH THE GROUND AS REFLECTED BY THE 00Z ECMWF. INCLUDED JUST A 20
PERCENT CHANCE OVER SOUTHEAST MN FOR NOW. CHANCES INCREASE
EVERYWHERE SUNDAY NIGHT...ESPECIALLY WEST OF THE MISSISSIPPI
RIVER...ASSOCIATED WITH THE TROUGH PUSHING EAST AND MORE IMPORTANTLY
THE LOW TO MID-LEVEL FRONTOGENESIS ZONE STRENGTHENING. INCREASED
CHANCES TOWARD 60 LATE IN THE NIGHT WEST OF HWY 52.
ANOTHER CONCERN TO WATCH IS A POTENTIAL WARM LAYER ACCOMPANYING THIS
SYSTEM. THE FASTEST 01.00Z NAM WOULD SUGGEST THAT THE PRECIPITATION
SUNDAY AFTERNOON OR EVENING WOULD START AS SLEET SAY IN THE AUSTIN
AREA. HOWEVER...SINCE A COMPROMISE APPROACH WAS FOLLOWED...ANY MIXED
PRECIPITATION TYPE TRANSITION ZONE SHOULD STAY OFF TO THE WEST.
.LONG TERM...MONDAY THROUGH THURSDAY NIGHT
308 AM CST FRI MAR 1 2013
MAIN CONCERN/FOCUS OF THE LONG TERM PERIOD REMAINS ON THE POTENT
UPPER TROUGH IN SOUTH DAKOTA EARLY MONDAY. THE 01.00Z
ECMWF/UKMET/CANADIAN AND GFS ENSEMBLES ARE ALL IN GOOD AGREEMENT
THAT THIS TROUGH WILL CLOSE OFF AND BE IN/NEAR WESTERN IOWA BY 12Z
TUESDAY. NOTE THAT THE 01.00Z GFS ALSO CLOSES IT OFF...BUT IS MUCH
MORE PROGRESSIVE...DOWN IN SOUTHERN MISSOURI AT 12Z TUESDAY. GIVEN
THE PREDOMINANCE OF SLOWER SOLUTIONS...DISCOUNTED THE GFS. THESE
SLOWER SOLUTIONS MEAN THAT A LOW TO MID-LEVEL FRONTOGENESIS BAND
WILL GET STUCK. WHEREVER THIS OCCURS THERE COULD END UP BEING SOME
DECENT SNOW ACCUMULATIONS. RIGHT NOW IT APPEARS THE BAND WOULD SET
UP FROM NORTH DAKOTA INTO SOUTHEAST MN AND INTO EASTERN IOWA. RAISED
PRECIPITATION CHANCES IN THIS AREA 20 PERCENT FROM THE PREVIOUS
FORECAST...AND MAY NEED TO BE RAISED MORE IF TRENDS CONTINUE.
A LONGWAVE TROUGH IS FORECAST TO TRY TO ENTER THE WEST COAST TUESDAY
NIGHT...WHICH MODELS HAVE SHOWN FOR AWHILE. THIS TROUGH WILL HELP
BUILD AND PUSH RIDGING EASTWARD...CAUSING THE UPPER LOW OVER WESTERN
IOWA TO SHIFT SOUTHEAST...AND PUSH THE LOW TO MID-LEVEL
FRONTOGENESIS CIRCULATION EASTWARD. THUS...THE SNOW MAY END UP
OVERSPREADING MUCH OF THE AREA ON TUESDAY AND ADDED 20-40 PERCENT
CHANCES AS A RESULT. EVEN ADDED A 20 PERCENT CHANCE OVER THE
SOUTHEAST 1/3 TUESDAY NIGHT.
WHEN ALL IS SAID AND DONE FROM THE SUNDAY NIGHT THROUGH TUESDAY
PERIOD...WE COULD BE LOOKING AT EITHER A LONG DURATION ADVISORY
EVENT OR EVEN WARNING IF THE 01.00Z CANADIAN ENDS UP RIGHT.
DEFINITELY NEED MODELS TO COME TO BETTER AGREEMENT AND MORE
DETAILS WORKED OUT BEFORE SPECULATING ON SNOWFALL AMOUNTS. 01.06Z
NAM CONTINUES TO SHOW AN AGGRESSIVE QPF SCENARIO SIMILAR TO THE
CANADIAN...ALONG WITH SPREADING PRECIPITATION FARTHER EAST. QUICK
LOOK AT THE 01.00Z ECMWF ENSEMBLE MEAN ALSO APPEARS TO BE IN-LINE
WITH THE NAM/CANADIAN IN TERMS OF 500MB HEIGHT AND MSLP. AS
MENTIONED...PLENTY OF DETAILS TO WORK OUT.
QUIET WEATHER ROUNDS OUT THE REST OF THE WEEK WITH MODELS IN GOOD
AGREEMENT SHIFTING THE UPPER RIDGE INTO THE FORECAST AREA. THIS
SHOULD BRING TEMPERATURES BACK UP TO NEAR OR POSSIBLY EVEN ABOVE
NORMAL BY THURSDAY. IF THE 01.00Z GFS IS CORRECT...WE COULD EVEN BE
LOOKING AT A RAIN/SNOW MIX THURSDAY NIGHT AS IT EJECTS OUT A
SHORTWAVE FROM THE WESTERN TROUGH THROUGH/NEARBY THE FORECAST AREA.
&&
.AVIATION...TODAY AND TONIGHT
537 AM CST FRI MAR 1 2013
STRATUS WILL PRODUCE MAINLY MVFR CONDITIONS AT THE TAF SITES INTO
EARLY THIS AFTERNOON WITH CLOUDS BASES AROUND 3000 FT AT KLSE AND
2500 FT AT KRST. WEAK HIGH PRESSURE IS EXPECTED TO GRADUALLY BUILD
IN THIS AFTERNOON WITH THE STRATUS BECOMING BROKEN TO SCATTERED.
WILL HAVE TO KEEP A CLOSE WATCH ON CLOUD TRENDS TODAY WITH
GUIDANCE NOT HANDLING THIS STRATUS LAYER VERY WELL THIS MORNING.
VFR CONDITIONS ARE EXPECTED THIS EVENING INTO THE OVERNIGHT HOURS
WITH SKIES BECOMING MOSTLY CLEAR. PLAN ON NORTH/NORTHEAST WINDS AT
5 TO 10 KTS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
308 AM CST FRI MAR 1 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
308 AM CST FRI MAR 1 2013
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
308 AM CST FRI MAR 1 2013
POTENTIAL FOR ACCUMULATING SNOW SUNDAY NIGHT AND HEADING INTO THE
LONG TERM PERIOD.
CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER THE WESTERN U.S. INTO ALBERTA AND GENERAL BROAD
TROUGHING OVER THE EAST HALF OF THE U.S.. THE FORECAST AREA SITS IN
A NON-DESCRIPT FLOW WITHIN THIS BROAD TROUGH...DUE TO THE MAIN JET
FLOW CONFINED OVER THE WESTERN DAKOTAS...AND AN UPPER LOW STUCK OVER
NEW ENGLAND. THIS NON-DESCRIPT FLOW HAS RESULTED IN THE VERY SLOW
SURFACE PATTERN PROGRESSION...WITH THE AREA STILL UNDER CYCLONIC
FLOW AROUND LOW PRESSURE IN NEW ENGLAND. A TROUGH EXTENDING WEST
FROM THE LOW EXTENDS WEST NEAR I-80 TO DES MOINES...THEN TO THE
NORTHWEST TO FARGO. SLOWLY DRIER AIR IS ADVECTING SOUTHWARD INTO THE
CYCLONIC CIRCULATION FROM HIGH PRESSURE OVER HUDSON BAY...RESULTING
IN CLEARING OVER NORTHERN LAKE SUPERIOR INTO THE NORTHERN 2/3 OF
MINNESOTA. HOWEVER...THE 00Z MPX AND GRB SOUNDINGS STILL SHOW A 50MB
SATURATED LAYER STUCK AROUND A COLD FRONTAL INVERSION SITTING AT
825MB. THUS...STRATUS STILL COVERS THE AREA. THIS STRATUS COMBINED
WITH A 5-10 KT NORTHEAST WIND HAS KEPT TEMPERATURES MAINLY IN THE
20S...DESPITE 850MB TEMPS AROUND -11C OR 1 STANDARD DEVIATION BELOW
NORMAL PER 00Z RAOBS.
SHORT TERM HIGHLIGHTS / CONCERNS:
1. WHEN WILL IT CLEAR
THIS IS A TWO PART ISSUE. FIRST AND MORE IMPORTANTLY IS THE GENERAL
STRATUS DECK IN PLACE. 01.00Z NAM WAS SURPRISINGLY TOO AGGRESSIVE
WITH CLEARING...SUGGESTING BASED ON 850MB AND 900MB RH FIELDS THAT
LOCATIONS NORTH OF I-90 WOULD BE CLEAR RIGHT NOW. LATEST RAP 850MB
AND 900MB RH GUIDANCE SEEMS TO HAVE A BETTER HANDLE ON THE LOW
CLOUDS...GRADUALLY CLEARING LOCATIONS NORTH OF I-90 NORTH TO SOUTH
THROUGH 21Z. A COMBINATION OF DAYTIME MIXING AND A STRONGER SURGE OF
DRY AIR FROM NORTHERN ONTARIO APPEARS TO BE AIDING IN THIS CLEARING.
SOUTH OF I-90...THE LOW CLOUDS MAY NOT DISSIPATE UNTIL SOMETIME
DURING THE EVENING. THE SECOND PART OF THE CLEARING ISSUE IS IN THE
UPPER LEVELS WHERE SCT-BKN CIRROSTRATUS EXISTS OVER THE AREA. THE
NON-DESCRIPT UPPER LEVEL FLOW WOULD SUGGEST CLEARING OF THE CIRRUS
WILL BE PROBLEMATIC. NAM/RAP 500-400MB RH FIELD CONFIRM THIS AS WELL
WITH MUCH OF THE AREA DOMINATED BY SCT-BKN CIRROSTRATUS THROUGH THE
DAY TODAY...ESPECIALLY OVER THE WESTERN HALF. IT LOOKS LIKE WE
FINALLY CAN CLEAR THESE HIGH CLOUDS OUT TONIGHT INTO SATURDAY
MORNING AS THE UPPER RIDGE OVER THE WESTERN U.S. BEGINS PROGRESSING
EAST.
2. TEMPERATURES TODAY THROUGH SATURDAY NIGHT
THE STRONGER NOW EARLY MARCH SUN CAN DEFINITELY WARM TEMPERATURES
UP...EVEN UNDER AN ENVIRONMENT OF COLD 850MB TEMPS...LIKE THOSE
TODAY AROUND -11C. HOWEVER...WITH ONLY PARTIAL CLEARING OVERALL
NORTH OF I-90...IT LOOKS TOUGH TO GET TEMPERATURES TO OR ABOVE
FREEZING. NAM 2 METER AND MET GUIDANCE LOOKS A BIT TOO OPTIMISTIC...
GIVEN THE FACT THAT IT HAS CLEARING MUCH EARLIER THAN WHAT WILL
OCCUR. HAVE LEANED MORE TOWARDS MAV/ECMWF/GEM GUIDANCE AS A RESULT.
RELATIVELY COOL CONDITIONS TODAY COMBINED WITH CLEARING TONIGHT AND
WINDS CALMING WITH HIGH PRESSURE BUILDING IN SETS THE STAGE FOR A
DECENT RADIATIONAL COOLING NIGHT. THUS...STAYED TOWARD THE COOL END
OF GUIDANCE. MUCH MORE SUN ON SATURDAY WITH SIMILAR 850MB TEMPS WILL
YIELD JUST A SLIGHTLY WARMER DAY. THE SURFACE HIGH PRESSURE RIDGE IS
PROGGED TO REMAIN NEARBY SATURDAY NIGHT...WHICH AGAIN PUTS A GOOD
RADIATIONAL COOLING NIGHT IN FOCUS. HOWEVER...MID AND HIGH CLOUDS
LOOK TO INCREASE COMING THROUGH THE UPPER RIDGE BUILDING TOWARDS US.
THUS...WE SHOULD NOT GET AS COOL AS TONIGHT. STILL...TIMING OF THE
CLOUDS IS EVERYTHING AND TYPICAL COLD SPOTS IN WISCONSIN COULD STILL
END UP PLUMMETING. THUS...FOR THE TYPICAL COLD SPOTS LEANED MORE
TOWARDS THE COLDER SIDE OF GUIDANCE FOR THEM.
3. POTENTIAL FOR WARM ADVECTION PRECIPITATION SUNDAY/SUNDAY NIGHT
MODELS ARE PROGGING THAT A POTENT UPPER TROUGH...CURRENTLY PRESENT
NEAR 45 N / 150W WELL SOUTH OF THE GULF OF ALASKA...WILL CRASH
THROUGH THE UPPER RIDGING BUILDING TOWARDS THE FORECAST AREA DURING
THE WEEKEND. BY 12Z SUNDAY...GOOD MODEL AGREEMENT EXISTS THAT THIS
POTENT UPPER TROUGH...PERHAPS IN THE FORM OF A CLOSED LOW...SHOULD
BE OVER WASHINGTON STATE. THERE STILL REMAINS SOME DISAGREEMENT ON
THE TRACK OF THE POTENT UPPER TROUGH AFTERWARDS...BUT THERE DOES
APPEAR TO BE A CONVERGING SOLUTION. BY 12Z MONDAY...THE TROUGH
SHOULD EXIST SOMEWHERE BETWEEN ENTERING WESTERN SOUTH DAKOTA
/SLOWER 01.00Z ECMWF/ TO SOUTHEAST SOUTH DAKOTA /FASTER 01.00Z NAM/.
THE SPEED FACTOR APPEARS TO BE RELATED TO HOW POTENT A SHORTWAVE IS
DROPPING THROUGH MICHIGAN ON SUNDAY...THE MORE POTENT THE SLOWER THE
UPPER TROUGH COMING ACROSS THE NORTHERN ROCKIES WILL BE. THIS
FORECAST IS GOING TO TAKE A CONSENSUS APPROACH TO THE 01.00Z
GUIDANCE...GIVEN THE CONVERGING TREND BUT AT THE SAME TIME ALLOWS
FOR A LITTLE CONTINUITY.
DETAILS...AS THE POTENT TROUGH DIGS INTO THE NORTHERN ROCKIES ON
SUNDAY...LOW PRESSURE DEEPENS DOWNSTREAM OVER SOUTH DAKOTA AND
NEBRASKA. IN TURN...WARM ADVECTION INTENSIFIES...DEVELOPING A MASS
OF MID CLOUDS FROM THE DAKOTAS INTO THE FORECAST AREA. THE 00Z
GFS/UKMET/CANADIAN ALL DEVELOP SOME LIGHT PRECIP WEST OF THE
MISSISSIPPI RIVER BETWEEN 18-00Z...BUT UNSURE IF THIS IS GOING TO
REACH THE GROUND AS REFLECTED BY THE 00Z ECMWF. INCLUDED JUST A 20
PERCENT CHANCE OVER SOUTHEAST MN FOR NOW. CHANCES INCREASE
EVERYWHERE SUNDAY NIGHT...ESPECIALLY WEST OF THE MISSISSIPPI
RIVER...ASSOCIATED WITH THE TROUGH PUSHING EAST AND MORE IMPORTANTLY
THE LOW TO MID-LEVEL FRONTOGENESIS ZONE STRENGTHENING. INCREASED
CHANCES TOWARD 60 LATE IN THE NIGHT WEST OF HWY 52.
ANOTHER CONCERN TO WATCH IS A POTENTIAL WARM LAYER ACCOMPANYING THIS
SYSTEM. THE FASTEST 01.00Z NAM WOULD SUGGEST THAT THE PRECIPITATION
SUNDAY AFTERNOON OR EVENING WOULD START AS SLEET SAY IN THE AUSTIN
AREA. HOWEVER...SINCE A COMPROMISE APPROACH WAS FOLLOWED...ANY MIXED
PRECIPITATION TYPE TRANSITION ZONE SHOULD STAY OFF TO THE WEST.
.LONG TERM...MONDAY THROUGH THURSDAY NIGHT
308 AM CST FRI MAR 1 2013
MAIN CONCERN/FOCUS OF THE LONG TERM PERIOD REMAINS ON THE POTENT
UPPER TROUGH IN SOUTH DAKOTA EARLY MONDAY. THE 01.00Z
ECMWF/UKMET/CANADIAN AND GFS ENSEMBLES ARE ALL IN GOOD AGREEMENT
THAT THIS TROUGH WILL CLOSE OFF AND BE IN/NEAR WESTERN IOWA BY 12Z
TUESDAY. NOTE THAT THE 01.00Z GFS ALSO CLOSES IT OFF...BUT IS MUCH
MORE PROGRESSIVE...DOWN IN SOUTHERN MISSOURI AT 12Z TUESDAY. GIVEN
THE PREDOMINANCE OF SLOWER SOLUTIONS...DISCOUNTED THE GFS. THESE
SLOWER SOLUTIONS MEAN THAT A LOW TO MID-LEVEL FRONTOGENESIS BAND
WILL GET STUCK. WHEREVER THIS OCCURS THERE COULD END UP BEING SOME
DECENT SNOW ACCUMULATIONS. RIGHT NOW IT APPEARS THE BAND WOULD SET
UP FROM NORTH DAKOTA INTO SOUTHEAST MN AND INTO EASTERN IOWA. RAISED
PRECIPITATION CHANCES IN THIS AREA 20 PERCENT FROM THE PREVIOUS
FORECAST...AND MAY NEED TO BE RAISED MORE IF TRENDS CONTINUE.
A LONGWAVE TROUGH IS FORECAST TO TRY TO ENTER THE WEST COAST TUESDAY
NIGHT...WHICH MODELS HAVE SHOWN FOR AWHILE. THIS TROUGH WILL HELP
BUILD AND PUSH RIDGING EASTWARD...CAUSING THE UPPER LOW OVER WESTERN
IOWA TO SHIFT SOUTHEAST...AND PUSH THE LOW TO MID-LEVEL
FRONTOGENESIS CIRCULATION EASTWARD. THUS...THE SNOW MAY END UP
OVERSPREADING MUCH OF THE AREA ON TUESDAY AND ADDED 20-40 PERCENT
CHANCES AS A RESULT. EVEN ADDED A 20 PERCENT CHANCE OVER THE
SOUTHEAST 1/3 TUESDAY NIGHT.
WHEN ALL IS SAID AND DONE FROM THE SUNDAY NIGHT THROUGH TUESDAY
PERIOD...WE COULD BE LOOKING AT EITHER A LONG DURATION ADVISORY
EVENT OR EVEN WARNING IF THE 01.00Z CANADIAN ENDS UP RIGHT.
DEFINITELY NEED MODELS TO COME TO BETTER AGREEMENT AND MORE
DETAILS WORKED OUT BEFORE SPECULATING ON SNOWFALL AMOUNTS. 01.06Z
NAM CONTINUES TO SHOW AN AGGRESSIVE QPF SCENARIO SIMILAR TO THE
CANADIAN...ALONG WITH SPREADING PRECIPITATION FARTHER EAST. QUICK
LOOK AT THE 01.00Z ECMWF ENSEMBLE MEAN ALSO APPEARS TO BE IN-LINE
WITH THE NAM/CANADIAN IN TERMS OF 500MB HEIGHT AND MSLP. AS
MENTIONED...PLENTY OF DETAILS TO WORK OUT.
QUIET WEATHER ROUNDS OUT THE REST OF THE WEEK WITH MODELS IN GOOD
AGREEMENT SHIFTING THE UPPER RIDGE INTO THE FORECAST AREA. THIS
SHOULD BRING TEMPERATURES BACK UP TO NEAR OR POSSIBLY EVEN ABOVE
NORMAL BY THURSDAY. IF THE 01.00Z GFS IS CORRECT...WE COULD EVEN BE
LOOKING AT A RAIN/SNOW MIX THURSDAY NIGHT AS IT EJECTS OUT A
SHORTWAVE FROM THE WESTERN TROUGH THROUGH/NEARBY THE FORECAST AREA.
&&
.AVIATION...
1035 PM CST THU FEB 28 2013
LATEST FOG/STRATUS SATELLITE TRENDS ALONG WITH RAP RH FIELDS/BUFKIT
SOUNDINGS FAVOR HOLDING THE MVFR CIGS ACROSS KRST/KLSE EVEN LONGER
NOW...PERHAPS FOR MOST OF THE DAYTIME HOURS. NAM BUFKIT SOUNDINGS
SUGGEST THAT MIXING COULD START UP BY MID/LATE MORNING...HELPING TO
ELEVATE THE CIGS...ALTHOUGH NOT NECESSARILY SCATTERING THIS LOW DECK
OUT UNTIL LATER IN THE AFTERNOON. CONFIDENCE REMAINS SHAKY WHEN THIS
WILL OCCUR...BUT WILL CONTINUE TO PUSH TIMING BACK...TOWARD THESE
LATEST TRENDS. HIGH CLOUDS WILL LIKELY BE FILTERING BACK ACROSS THE
REGION EVEN AS THE LOW CLOUDS IF/WHEN VACATE TO THE
SOUTH...ASSOCIATED WITH A WEAK UPPER LEVEL DISTURBANCE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
308 AM CST FRI MAR 1 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1035 PM CST THU FEB 28 2013
.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT
315 PM CST THU FEB 28 2013
AT 3 PM...CLOUDS CONTINUE TO PIVOT AROUND A LOW PRESSURE SYSTEM
CENTERED OVER SOUTHEAST ONTARIO. HOWEVER SOME DRIER AIR FILTERING
INTO NORTHERN MINNESOTA...UPPER MICHIGAN...AND NORTHERN WISCONSIN
IS CAUSING SOME BREAKS TO DEVELOP IN THE MVFR DECK. BUFKIT SOUNDINGS
SUGGEST THAT THE CLOUDS WILL LINGER ACROSS THE FORECAST AREA
TONIGHT...AND THEN GRADUALLY BREAK UP FROM NORTHEAST TO SOUTHWEST
ON FRIDAY. AT THE SAME TIME...SOME MID AND HIGH CLOUDS WILL BE
MOVING INTO THE AREA FROM THE WEST AS A WEAKENING SHORT WAVE
/CURRENTLY OVER THE DAKOTAS/ MOVES EAST TOWARD THE FORECAST AREA.
WITH SKIES EXPECTED TO REMAIN CLOUDY TONIGHT...ONCE AGAIN WENT
HIGHER THAN THE MAV AND MET MOS TEMPERATURES. A 50-50 BLEND
OF LAST NIGHT/S MINIMUM TEMPERATURES AND THE BIAS CORRECTED
CONSALL...RAISED THE MINIMUM TEMPERATURES INTO THE MID AND
UPPER TEENS ACROSS NORTH-CENTRAL WISCONSIN...AND LOWER AND MID 20S
ACROSS THE REMAINDER OF THE FORECAST AREA. THIS SEEMS MUCH MORE
REALISTIC THAN THE MOS.
ALSO FOR TONIGHT...A WEAK 850-700 MB WILL MOVE SOUTH THROUGH
THE AREA TONIGHT. IN ADDITION...THERE IS SOME WEAK 275 ISENTROPIC
LIFT. SOUNDINGS SUGGEST THAT THE OMEGA ASSOCIATED WITH THIS
FEATURE WILL BE CO-LOCATED WITH THE LOW LEVEL MOISTURE. AS A
RESULT...KEPT SCATTERED FLURRIES IN THE FORECAST.
ON SATURDAY NIGHT...THE MODELS SHOW THAT A WEAKENING TROUGH WILL
MOVE INTO THE UPPER LEVEL RIDGE. WEAK TO MODERATE 280K ISENTROPIC
LIFT DEVELOPS AHEAD OF THIS TROUGH. THE 28.00Z NAM/WRF CONTINUES
TO SHOW SOME LIGHT PRECIPITATION ASSOCIATED WITH THIS SYSTEM.
THE ECMWF GENERATES SOME FLURRIES WITH THIS SYSTEM. MEANWHILE THE
GEM AND OPERATIONAL GFS KEEPS THE AREA DRY. LOOKING AT THE 12 GFS
MEMBERS...ONLY 3 OF THEM GENERATE ANY MEASURABLE PRECIPITATION.
THE MAIN DIFFERENCE BETWEEN THE GFS AND NAM IN THE BUFKIT
SOUNDINGS IS HOW THEY HANDLE THE DRY AIR BELOW 5K FEET. THE
NAM/WRF SATURATES THIS LAYER. MEANWHILE THE GFS SHOWS THAT THIS
LAYER WILL REMAIN VERY DRY. WITH UNCERTAINTIES IN THE LOW LEVEL
MOISTURE...JUST OPTED TO GO WITH FLURRIES AT THIS TIME.
.LONG TERM...SUNDAY THROUGH THURSDAY
315 PM CST THU FEB 28 2013
FROM LATE SUNDAY NIGHT INTO TUESDAY...THE MAIN FORECAST CONCERN IS
THE TRACK OF A LOW PRESSURE SYSTEM MOVING THROUGH THE REGION. BOTH
THE GFS AND ECMWF HAVE SHIFTED THE TRACK OF THIS LOW EVEN FURTHER
SOUTH OF ITS TRACK AT 28.00Z AND 28.06Z. WITH THIS TRACK...IT
WOULD ONLY AFFECT SOUTHEAST MINNESOTA AND NORTHEAST IOWA. MEANWHILE
THE GEM KEEPS THE SYSTEM TRACKING TO OUR NORTH. WITH THIS
TRACK...IT CONTINUES TO PRODUCE PRECIPITATION ACROSS THE ENTIRE
AREA. WITH THE MODELS STILL TRYING TO SORT OUT THINGS...OPTED TO
STAY WILL ALL BLEND FOR NOW.
BEYOND THIS TIME PERIOD...IT CONTINUES TO LOOK LIKE A 500 MB RIDGE
WILL DEVELOP ACROSS THE CENTRAL UNITED STATES. AS STATED
YESTERDAY...THIS IS ACTUALLY SUPPORTED BY MADDEN JULIAN
OSCILLATIONS FOR PHASES 6 AND 7. WHILE THERE IS AGREEMENT THAT
THIS RIDGE WILL BE BUILDING ACROSS THE AREA...THERE IS STILL SOME
UNCERTAINTY ON HOW WARM WE WILL GET.
&&
.AVIATION...
1035 PM CST THU FEB 28 2013
LATEST FOG/STRATUS SATELLITE TRENDS ALONG WITH RAP RH FIELDS/BUFKIT
SOUNDINGS FAVOR HOLDING THE MVFR CIGS ACROSS KRST/KLSE EVEN LONGER
NOW...PERHAPS FOR MOST OF THE DAYTIME HOURS. NAM BUFKIT SOUNDINGS
SUGGEST THAT MIXING COULD START UP BY MID/LATE MORNING...HELPING TO
ELEVATE THE CIGS...ALTHOUGH NOT NECESSARILY SCATTERING THIS LOW DECK
OUT UNTIL LATER IN THE AFTERNOON. CONFIDENCE REMAINS SHAKY WHEN THIS
WILL OCCUR...BUT WILL CONTINUE TO PUSH TIMING BACK...TOWARD THESE
LATEST TRENDS. HIGH CLOUDS WILL LIKELY BE FILTERING BACK ACROSS THE
REGION EVEN AS THE LOW CLOUDS IF/WHEN VACATE TO THE
SOUTH...ASSOCIATED WITH A WEAK UPPER LEVEL DISTURBANCE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
228 PM CST THU FEB 28 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM....BOYNE
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
409 AM EST SUN MAR 3 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT AND REMAIN
THROUGH EARLY THIS WEEK. LOW PRESSURE AND ITS TRAILING COLD FRONT
WILL IMPACT THE AREA TUESDAY NIGHT INTO EARLY WEDNESDAY...FOLLOWED
AGAIN BY HIGH PRESSURE THROUGH LATE WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
THE REGION WILL REMAIN UNDER THE INFLUENCE OF A DEEP LONGWAVE
TROUGH TODAY. THE TROUGH IS FORECAST TO GRADUALLY PUSH OFFSHORE AS
THE DAY PROGRESSES ALLOWING MID-LEVEL HEIGHTS TO STEADILY RISE IN
ITS WAKE. ALTHOUGH THE MID-LEVEL THERMAL ADVECTION PATTERN WILL
BECOME NEUTRAL TO SLIGHTLY POSITIVE LATER TODAY...H8 TEMPERATURES
OF -6 TO -7C WILL STILL KEEP HIGH TEMPERATURES ABOUT 10-15 DEGREES
BELOW NORMAL FOR EARLY MARCH. LOW-LEVEL THICKNESSES SCHEMES
SUPPORT HIGHS IN THE LOWER 50S WHICH LOOK REASONABLE PER MODEL
BUFR SOUNDINGS.
STEEP MID-LEVEL LAPSE RATES NEARING 6 C/KM COUPLED WITH SOME
LINGERING MID-LEVEL MOISTURE WILL LIKELY SUPPORT THE FORMATION OF
SOME SORT OF SHALLOW CUMULUS FIELD ONCE THE NOCTURNAL INVERSION
BURNS OFF. HOWEVER...IT IS UNCLEAR HOW EXTENSIVE THIS CLOUD DECK
WILL BECOME. BUFKIT CLOUD TOOLS SUGGEST A RATHER THICK 6 KFT CLOUD
LAYER WILL FORM...WHILE OTHER DATA SUCH AS THE WRF AND GEM
SIMULATED SATELLITE PRODUCTS SUPPORT CONSIDERABLY LESS CLOUD
COVER. CONSIDERING THE H9-H7 FLOW DOES NOT BECOME TRULY DOWNSLOPE
DOMINATED UNTIL MID-LATE AFTERNOON...SUSPECT THERE WILL BE ENOUGH
CLOUDS TO SUPPORT A PARTLY CLOUDY SKY CHARACTER...HOWEVER SKIES
RANGING ANYWHERE FROM CLOUDY TO COMPLETELY SUNNY ARE DISTINCT
POSSIBILITIES.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
TONIGHT...SURFACE HIGH PRESSURE WILL BUILD IN FROM THE WEST
TONIGHT AS WEAK UPPER RIDGING OVER THE SOUTHERN PLAINS NUDGES
EAST. THERE LOOKS TO BE ENOUGH OF A RESIDUAL PRESSURE GRADIENT
ALONG THE EASTERN FLANKS OF THE SURFACE HIGH TO PREVENT FULL
BOUNDARY LAYER DECOUPLING AFTER SUNSET...EXCEPT OVER INTERIOR
SOUTHEAST GEORGIA WHERE DECOUPLING APPEARS MORE LIKELY. LOWS WILL
RANGE FROM THE UPPER 20S INLAND TO THE MID 30S AT THE BEACHES WITH
A FEW MID 20S LIKELY IN SOME SHELTERED AREAS OF FAR INTERIOR
SOUTHEAST GEORGIA.
MONDAY...SURFACE HIGH PRESSURE AND SHORTWAVE RIDGING ALOFT WILL
QUICKLY FOLLOW IN THE WAKE OF THE DEPARTING UPPER TROUGH EARLY IN
THE DAY. MODEL FORECAST SOUNDINGS INDICATE DEEP LAYER DRY AIR DURING
THE DAYTIME HOURS WITHIN A PREDOMINANT WEST/NORTHWEST FLOW. HIGH
LEVEL CLOUDS COULD THEN SHIFT INTO THE AREA OVERNIGHT DOWNSTREAM OF
A DEVELOPING LOW IN THE LOWER MISSISSIPPI/TENNESSEE VALLEYS. RISING
HEIGHTS ALOFT AND MOSTLY CLEAR TO PARTLY CLOUDY SKIES WILL SUPPORT
MODERATING TEMPERATURES...WITH HIGHS REACHING THE UPPER 50S TO LOWER
60S AWAY FROM THE LOCALLY COOLER COASTLINE. LOW LEVEL FLOW WILL BACK
TO THE SOUTHWEST OVERNIGHT...AND WITH EVIDENCE OF SOME HIGHER LEVEL
CLOUDS PROVIDING INSULATING EFFECTS AFTER MIDNIGHT...EXPECT LOW
TEMPERATURES TO BE NEARLY 10 DEGREES WARMER THAN THE PREVIOUS NIGHT.
LOWS WILL THUS RANGE FROM THE UPPER 30S INLAND TO THE LOWER 40S NEAR
THE BEACHES.
TUESDAY...A POTENT SHORTWAVE TROUGH WILL DESCEND FROM THE NORTHERN
PLAINS STATES INTO THE MID MISSISSIPPI VALLEY THROUGH THE AFTERNOON
HOURS...PROVIDING SIGNIFICANT ENERGY TO ORGANIZE AND INTENSIFY A
SURFACE LOW SYSTEM OVER THE TENNESSEE VALLEY BY SUNSET. THE UPPER
TROUGH WILL DEVELOP INTO A CUT OFF LOW OVERNIGHT...AT THE SAME TIME
THAT THE SURFACE SYSTEM BECOMES MORE COMPLEX AND TRACKS DUE
EASTWARD THROUGH THE CAROLINAS AND MID ATLANTIC STATES BY DAYBREAK
WEDNESDAY. THE FORECAST AREA WILL BE LOCATED WITHIN THE WARM
SECTOR OF THE SYSTEM DURING THE DAYTIME HOURS TUESDAY...WITH
SOUTHERLY FLOW SUPPORTING TEMPERATURES RISING INTO THE UPPER 60S
NORTHWEST ZONES TO THE LOWER 70S SOUTH OF THE SAVANNAH RIVER. WITH
THE FORECAST AREA INITIALLY LOCATED SOUTH OF THE WARM FRONT AND
WEST OF THE APPROACHING COLD FRONT...EXPECT RAIN TO BE SLOW TO
PUSH INTO THE REGION THROUGH THE AFTERNOON HOURS. RAIN CHANCES
WILL THEN INCREASE SIGNIFICANTLY AFTER SUNSET ONCE THE FRONT AND
UPPER LOW PASS OVER THE SOUTHEAST AND MID ATLANTIC STATES. GIVEN
DECENT MODEL AGREEMENT IN POTENTIAL AND COVERAGE OF RAIN...HAVE
INCREASED POPS INTO THE LIKELY RANGE FOR MUCH OF THE FORECAST AREA
FROM AROUND MIDNIGHT TO DAYBREAK WEDNESDAY MORNING. THICK
INSULATING CLOUD COVER...ALONG WITH SOUTHERLY FLOW VEERING TO THE
WEST...WILL KEEP LOW TEMPERATURES TUESDAY NIGHT RATHER MILD IN THE
UPPER 40S TO LOWER 50S.
WEDNESDAY...THE STACKED AND INTENSIFYING LOW SYSTEM WILL LIFT
EAST/NORTHEAST DURING THE MORNING HOURS...WHILE THE TRAILING COLD
FRONT RAPIDLY MOVES OFFSHORE. RAIN CHANCES WILL BE DECREASING FROM
WEST TO EAST INTO THE EARLY AFTERNOON...AND WITH THE SURFACE LOW
DISPLACED NORTH OF THE FORECAST AREA BY DAYBREAK...WRAP AROUND
MOISTURE DOES NOT APPEAR TO BE A CONCERN AT THIS TIME. HIGH
TEMPERATURES WILL BE COOLER IN THE UPPER 50S TO LOWER 60S BEHIND
THE DEPARTING COLD FRONT...HOWEVER MODERATE TO STRONG
OFFSHORE/DOWNSLOPE FLOW AND LINGERING CLOUD COVER WILL MITIGATE
MORE SIGNIFICANT COOLING POTENTIAL. A GREATLY TIGHTENED PRESSURE
GRADIENT ON THE BACKSIDE OF THE SURFACE LOW...AS WELL AS COLD
ADVECTION ENHANCING MIXING INTO A 30 TO 40 KT LOW LEVEL
JET...SUGGESTS BREEZY TO GUSTY WEST WINDS DURING THE AFTERNOON
HOURS.
LAKE WINDS...WINDS WILL APPROACH ADVISORY CRITERIA TUESDAY
AFTERNOON AS A 40 KT LOW LEVEL JET PASSES OVER THE REGION.
HOWEVER...MIXING WILL BE LIMITED WITHIN A WARM ADVECTION REGIME
OVER THE COOLER LAKE WATERS. A BETTER CHANCE FOR LAKE WIND
ADVISORY THRESHOLDS TO BE MET IS ON WEDNESDAY...AS A SIGNIFICANTLY
TIGHTENED PRESSURE GRADIENT AND STRONG COLD ADVECTION ENHANCES
MIXING AND SUPPORTS 20 TO 25 KT WINDS OVER THE LAKE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS THE POTENT LOW SYSTEM RAPIDLY TRACKS INTO THE ATLANTIC THROUGH
THE LATE WEEK PERIOD...SURFACE HIGH PRESSURE AND UPPER LEVEL
RIDGING WILL FOLLOW IN ITS WAKE. EXPECT DRY CONDITIONS TO THUS
PREVAIL THURSDAY THROUGH THE WEEKEND. RISING HEIGHTS ALOFT WILL
SUPPORT A GRADUAL WARMING TREND THROUGH THE PERIOD...WITH
TEMPERATURES PEAKING IN THE LOW TO MID 60S THURSDAY AND
FRIDAY...THEN POSSIBLY THE LOW 70S SATURDAY AND SUNDAY. LOW
TEMPERATURES WILL ALSO MODERATE INTO THE UPPER 30S TO LOWER 40S BY
LATE PERIOD.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
VFR.
EXTENDED AVIATION OUTLOOK...LOW TO MODERATE CHANCE OF REDUCED
CEILINGS/VISIBILITIES AT TIMES LATE TUESDAY INTO WEDNESDAY. WINDY
CONDITIONS WILL ALSO IMPACT THE TERMINALS TUESDAY AFTERNOON
THROUGH THURSDAY.
&&
.MARINE...
THIS MORNING...WINDS REMAIN QUITE RISKY AT BUOY 41008 WHICH IS A
BIT HIGHER THAN THE LATEST RAP RUN. WILL EXTEND THE SMALL CRAFT
ADVISORY FOR BOTH GEORGIA LEGS UNTIL 8 AM.
TODAY...WINDS WILL SLOWLY SUBSIDE ACROSS THE MARINE AREA TODAY AS
COLD AIR ADVECTION STEADILY WANES. ONCE THE MORNING SURGE
CEASES...EXPECT WINDS TO SETTLE INTO THE 10-15 KT RANGE...EXCEPT
15-20 KT OVER THE GEORGIA OFFSHORE WATERS. SEAS WILL RANGE FROM
2-3 FT NEARSHORE WATERS AND 3-4 FT OFFSHORE WATERS
TONIGHT...ANOTHER SURGE LOOKS LIKELY OVER THE WATERS TONIGHT AS
THE PRESSURE GRADIENT TIGHTENS A BIT AHEAD OF HIGH PRESSURE
NUDGING IN FROM THE WEST. SHOULD SEE AT LEAST FREQUENT GUSTS TO 25
KT OCCUR OVER THE WARMER WATERS ACROSS THE EASTERN PORTIONS FOR
THE GEORGIA OFFSHORE LEG...SO A SMALL CRAFT ADVISORY WILL LIKELY
BE NEEDED THERE. IT LOOKS A BIT MORE MARGINAL OVER THE NEARSHORE
WATERS SO WILL NOT HOIST AN ADVISORY JUST YET. SEAS WILL RANGE
FROM 2-4 FT NEARSHORE WATERS...4-6 FT OFFSHORE WATERS.
MONDAY...COLD ADVECTION WILL DIMINISH BY MID MORNING...AND ANY
SMALL CRAFT ADVISORIES SHOULD BE ALLOWED TO EXPIRE AT THAT TIME.
SOUTHERLY FLOW WILL THEN REMAIN BELOW ADVISORY THRESHOLDS FOR THE
REMAINDER OF THE DAY...AS HIGH PRESSURE BUILDS IN FROM FLORIDA AND
SETTLES OVER THE MARINE ZONES.
TUESDAY THROUGH THURSDAY...CONDITIONS WILL DETERIORATE AGAIN BY
LATER TUESDAY...AS ATLANTIC HIGH PRESSURE SHIFTS FARTHER AWAY FROM
THE MARINE ZONES AHEAD OF AN INTENSIFYING LOW PRESSURE SYSTEM
MOVING INTO THE TENNESSEE VALLEY. THE POTENT LOW SYSTEM WILL
INTENSIFY AS IT SHIFTS INTO THE CAROLINAS LATE TUESDAY/EARLY
WEDNESDAY AND THEN OFF THE MID ATLANTIC COAST WEDNESDAY
NIGHT/THURSDAY. A TRAILING COLD FRONT WILL SWEEP THROUGH THE
MARINE ZONES LATE TUESDAY NIGHT INTO EARLY WEDNESDAY. SMALL CRAFT
ADVISORY CRITERIA WILL BE REACHED BOTH AHEAD OF THE FRONT AND IN
ITS WAKE DURING THE MID WEEK PERIOD...WHILE THERE IS ALSO A GOOD
POTENTIAL FOR GALE CONDITIONS TO BE REACHED. WILL CONTINUE TO
MENTION THIS POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EST EARLY THIS MORNING FOR
AMZ354-374.
&&
$$
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1208 AM EST SUN MAR 3 2013
.SYNOPSIS...
A TROUGH OF LOW PRESSURE WILL PUSH EAST OF THE REGION OVERNIGHT
AND WILL BE FOLLOWED BY HIGH PRESSURE INTO EARLY IN THE UPCOMING
WEEK. A LOW PRESSURE SYSTEM AND ITS TRAILING COLD FRONT WILL
IMPACT THE AREA TUESDAY NIGHT INTO EARLY WEDNESDAY...FOLLOWED
AGAIN BY HIGH PRESSURE THROUGH LATE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A LINGERING BATCH OF STRATOCUMULUS PERSISTS FROM THE CENTRAL
MIDLANDS INTO THE PEE DEE AND EXTENDING SOUTH INTO INTERIOR PARTS
OF SOUTHEAST SOUTH CAROLINA. RUC RH FIELDS SUGGEST THESE CLOUDS
WILL LINGER A BIT LONGER AS THEY SLOWLY PUSH EAST. THESE CLOUDS ARE
THINNING WITH TIME...SO STILL ANTICIPATE A DECENT AMOUNT OF
CLEARING TO OCCUR ACROSS THE NORTHERN ZONES PRIOR TO DAYBREAK.
ELSEWHERE...MOSTLY CLEAR SKIES WILL CONTINUE. OTHER THAN ADJUSTING
SKY COVER A BIT PER GOING TRENDS...NO MAJOR CHANGES WERE NEEDED TO
THE REMAINDER OF THE FORECAST.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
SUNDAY...ONE LAST SHORT WAVE WILL MOVE THROUGH THE LONG WAVE TROUGH
IN THE EST DURING MIDDAY AND THE AFTERNOON...KEEPING THE COOL AIR
MASS IN PLACE ACROSS THE LOW COUNTRY AND COASTAL EMPIRE. BUT WITH
CONSIDERABLE DRYING OF THE TROPOSPHERE AND PWATS NO MORE THAN 1/4 TO
1/3 INCH...THIS WILL RESULT IN NO MORE THAN SCATTERED TO PERHAPS
OCCASIONAL BROKEN STRATOCUMULUS CLOUDS AROUND 5K FEET. THE FORECAST
AREA WILL BE SITUATED IN A REGIME CAUGHT BETWEEN THE FAR EXTENSION
OF CYCLONIC CIRCULATION AROUND A DEEP RETROGRADING LOW OFF THE SE
CANADIAN MARITIMES...AND HIGH PRESSURE CENTERED IN THE NW GULF. THIS
WILL KEEP SOME PACKING TO THE PRESSURE GRADIENT TO ALLOW FOR NW
WINDS OF 10-20 MPH. COLD ADVECTION WILL DROP OFF BY LATE
MORNING...AND WITH MORE INSOLATION THAN WE EXPERIENCED TODAY WE
WON/T BE QUITE AS COOL. WE STAYED CLOSE TO THE 1000-850 MB THICKNESS
FORECAST...WHICH SUPPORTS 50-53 FOR HIGHS OR ABOUT 10-15F BELOW
CLIMATOLOGICAL NORMS.
SUNDAY NIGHT...THE EASTERN TROUGH LIFTS OUT ALOFT...WHILE AT THE
SURFACE THE INTENSE LOW WILL HEAD TOWARD COASTAL MAINE. THIS
CONTINUES TO BLOCK THE PROGRESSION OF THE GULF OF MEXICO HIGH
PRESSURE SYSTEM...AND PREVENTS TOTAL DECOUPLING UNTIL MAYBE VERY
LATE ACROSS OUR FAR SW ZONES. AS OUR GEOSTROPHIC WIND FIELDS DECLINE
TO NO LOWER THAN 10 OR 15 KT...IT LOOKS LIKE ANOTHER ADVECTIVE
FREEZE. FOR THAT REASON WE/LL SHOW MIN TEMPS OF 27-32 INLAND FROM
US-17...WITH MIDDLE 30S CLOSER TO THE COAST. THE CAVEAT BEING THAT
IF WINDS DO FULLY DECOUPLE THAT THE INLAND SECTIONS COULD BE A TAD
COLDER GIVEN CLEAR TO MOSTLY CLEAR SKIES.
MONDAY...RIDGING DEVELOPS ALOFT AND BRINGS WITH IT THE SURFACE
HIGH...WHOSE AXIS SLIPS INTO THE ATLANTIC BY LATE IN THE DAY. OTHER
THAN AN INCREASE IN JET STREAM CIRRUS COURTESY OF A 100 KT OR
GREATER SOUTHERN JET...SKIES WILL BE FAIRLY SUNNY. 850 MB TEMPS WILL
RISE TO BETWEEN 3C NORTH AND 6C SOUTH...WHILE LOW LEVEL THICKNESS
VALUES CLIMB A SOLID 25-30 METERS FROM THE PREVIOUS 24 HOURS. WE/LL
GAIN ABOUT 4-8 DEGREES ON OUR MAX TEMPS...BUT AGAIN WELL BELOW
TYPICAL EARLY MARCH THRESHOLDS.
TUESDAY...THE PROGRESSIVE PATTERN ALOFT WILL SEE THE TRANSITION FROM
RIDGING OVERHEAD IN THE MORNING BEING FORCED EAST IN THE
AFTERNOON...AS A POTENT SHORT WAVE /FOUND OFF THE PACIFIC NW
COASTLINE LATE SATURDAY/ DROPS INTO THE MID MS VALLEY. AS THIS
OCCURS...IT ALLOWS FOR BETTER ORGANIZATION TO A 1006 MB SURFACE LOW
THAT TREKS EAST AND NE INTO THE OH/TN VALLEYS. ASSOCIATED WITH THIS
FEATURE IS AN EAST-WEST ORIENTED WARM FRONT THAT WILL STRETCH ACROSS
NC...AND A NE-SW ALIGNED COLD FRONT THAT WILL REMAIN WEST OF THE
APPALACHIANS UNTIL IT CROSSES THE SOUTHERN BRANCH OF THAT CHAIN LATE
IN THE DAY. WHILE WE DO EXPERIENCE A STEADY CLIMB IN MOISTURE...THE
BEST LOW LEVEL FORCING AND DYNAMICS ALOFT REMAIN OFF TO THE WEST AND
NW. WE/LL TRIM BACK POPS INTO THE SLIGHT CHANCE RANGE FOR THE
AFTERNOON ALONG THE NW TIER OF COUNTIES. 850 MB TEMPS WILL RISE
ANOTHER 2-3C...ALONG WITH LOW LEVEL THICKNESS STRETCHING ANOTHER
20-30 METERS. COMBINED WITH A WARMING SW SYNOPTIC FLOW...WARM
ADVECTION WILL PUSH TEMPS UP TO AT LEAST 65-70 AWAY FROM THE COOLER
COASTAL COMMUNITIES. MEANWHILE...THERE IS A TIGHTENING OF THE
PRESSURE GRADIENT DURING THE AFTERNOON BETWEEN HIGH PRESSURE OFF THE
FL EAST COAST AND THE UPSTREAM LOW PRESSURE SYSTEM. THIS WILL
PRODUCE SW BREEZES OF A SOLID 15-25 MPH WITH HIGHER GUSTS.
LAKE WINDS...WE/LL BE CLOSE TO LAKE ADVISORY CRITERIA ON LAKE
MOULTRIE IN THE AFTERNOON AS A STEADILY TIGHTER GRADIENT WILL TAKE
HOLD. BUT SINCE THE LAKE TEMPS WILL ONLY BE IN THE LOWER 50S...THE
BEST MIXING WILL BE LIMITED TO THE SHORELINE LOCATIONS.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS MORE INTENSE ENERGY ALOFT FLOWS INTO THE UPPER TROUGH...THE
FEATURE WILL LIKELY DEVELOP INTO A CUT OFF LOW...FURTHER
SUPPORTING THE DEEPENING OF THE SURFACE LOW AS IT PASSES DIRECTLY
OVER THE CAROLINAS TUESDAY NIGHT. THE ASSOCIATED COLD FRONT WILL
SWING THROUGH THE REGION DURING THE MORNING HOURS ON
WEDNESDAY...AND LIKELY BE QUICKLY OFFSHORE BY WEDNESDAY AFTERNOON.
THUS EXPECT THE BEST RAIN CHANCES TO OCCUR TUESDAY NIGHT INTO
EARLY WEDNESDAY MORNING...WITH PRECIPITATION ENDING FROM SOUTHWEST
TO NORTHEAST WEDNESDAY AFTERNOON FOLLOWING THE DEPARTING LOW
SYSTEM AND COLD FRONT. THICK CLOUD COVER AND WARM SOUTHERLY FLOW
AHEAD OF THE FRONT WILL KEEP LOW TEMPERATURES IN THE 40 DEGREE
RANGE TUESDAY NIGHT. TEMPERATURES ON WEDNESDAY WILL ONLY BE A FEW
DEGREES COOLER THAN THE PREVIOUS DAY DESPITE FRONTAL PASSAGE..WITH
HIGH TEMPERATURES COOLING JUST A FEW DEGREES. AS THE POTENT LOW
SYSTEM RAPIDLY TRACKS INTO THE ATLANTIC THROUGH THE LATE WEEK
PERIOD...SURFACE HIGH PRESSURE AND UPPER LEVEL RIDGING WILL FOLLOW
IN ITS WAKE. EXPECT DRY CONDITIONS TO THUS PREVAIL THURSDAY
THROUGH SATURDAY...WITH TEMPERATURES PEAKING IN THE LOW TO MID 60S
DURING THE AFTERNOON HOURS AND FALLING INTO THE UPPER 30S INLAND
TO LOWER 40S COASTLINE EACH NIGHT.
LAKE WINDS...A TIGHT PRESSURE GRADIENT ASSOCIATED WITH DEEP LOW
PRESSURE THAT MOVES FROM THE CENTRAL APPALACHIANS TO THE MID
ATLANTIC REGION...AND PERIODIC COLD ADVECTION IN WAKE OF A COLD
FRONT WILL IMPACT LAKE MOULTRIE. AS A RESULT..A LAKE WIND ADVISORY
APPEARS HIGHLY LIKELY DURING THE MIDDLE OF THE WEEK.
&&
.AVIATION /05Z SUNDAY THROUGH THURSDAY/...
VFR.
EXTENDED AVIATION OUTLOOK...LOW TO MODERATE CHANCE OF LOWERED
CEILINGS/VISIBILITIES AT TIMES LATE TUESDAY INTO WEDNESDAY. WINDY
CONDITIONS WILL ALSO IMPACT THE TERMINALS TUESDAY AFTERNOON
THROUGH THURSDAY.
&&
.MARINE...
OVERNIGHT...W/NW WINDS 15-25 KT/SMALL CRAFT ADVISORIES WILL
CONTINUE ACROSS GA WATERS. ACROSS SC WATERS...CAPPED WINDS AT 20
KT WITHIN THE COLD ADVECTION PATTERN OVERNIGHT. SEAS WILL RANGE
FROM 2-4 FT WITHIN NEARSHORE WATERS TO 4-5 FT BEYOND 20 NM.
SUNDAY...ANY ONGOING SCA/S AT THE START OF THE DAY WILL QUICKLY COME
DOWN AS COLD ADVECTION WANES. OTHERWISE THERE IS STILL A GOOD 2-3 MB
SPREAD OF ISOBARS ACROSS THE WATERS...WHICH WILL KEEP NW WINDS UP IN
THE RANGE OF 13-18 KT AND GUSTY THROUGH THE BULK OF THE DAY. SEAS
WILL BE HELD TO MAINLY 2-3 FT WITHIN 20 NM OF THE COST AND 3-5 FT
FURTHER OUT DUE TO THE OFFSHORE FETCH.
SUNDAY NIGHT...ANOTHER SURGE OF COLD ADVECTION WILL TRIGGER THE
DEVELOPMENT OF SCA CONDITIONS YET AGAIN. WHILE IT IS MOST LIKELY
ACROSS AMZ374...THE NEAR SHORE LEGS COULD ALSO EXPERIENCE MARGINAL
SCA/S.
MONDAY...MORNING COLD ADVECTION DROPS OFF BY AROUND 15Z...AND THE
SCA FLAGS WILL COME DOWN OVER THE ATLANTIC COASTAL WATERS.
CONDITIONS WILL THEN QUIET DOWN FOR THE AFTERNOON...AS HIGH PRESSURE
BUILDS IN FROM FLORIDA AND SETTLES ATOP THE AREA.
TUESDAY THROUGH THURSDAY...CONDITIONS WILL DETERIORATE AGAIN BY
LATER TUESDAY AS ATLANTIC HIGH PRESSURE GIVES TO AN UPSTREAM LOW
PRESSURE SYSTEM THAT MOVES INTO THE TN VALLEY. THAT LOW WILL THEN
SLOWLY INTENSIFY AS IT PASSES EAST OF THE MOUNTAINS TUESDAY
NIGHT...INTO NC ON WEDNESDAY...AND OFF THE MID ATLANTIC COAST
WEDNESDAY NIGHT/THURSDAY. A COLD FRONT TRAILING FROM THAT LOW WILL
SWEEP THROUGH THE MARINE COMMUNITY LATE TUESDAY NIGHT OR EARLY
WEDNESDAY. WE/LL MOST LIKELY HAVE THE NEED FOR AT LEAST SCA/S BOTH
PRE-FRONT AND POST-FRONT DURING THE MID WEEK PERIOD...BUT THERE IS
ALSO A FAIRLY DECENT SHOT OF GALE CONDITIONS DEVELOPING. WE/LL
CONTINUE TO MAINTAIN MENTION IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR
AMZ354-374.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1127 PM CST SAT MAR 2 2013
.DISCUSSION...
821 PM CST
MADE SOME MINOR ADJUSTMENTS TO FORECAST/GRIDS. WEAK LAKE EFFECT
SNOW BAND HAS DRIFTED WEST TO THE ILLINOIS SHORE SO HAVE ADDED
SOME SMALL POPS FOR LIGHT SNOW SHOWERS. LATEST SHORT TERM
GUIDANCE FROM HRRR AND RAP WOULD SUGGEST WEAK CONVERGENCE ZONE
WILL REMAIN DOWN CENTER-WEST SIDE OF LAKE OVERNIGHT. MAIN BAND
WILL BE COMING INTO NORTHWEST INDIANA BUT AS THE BAND
MEANDERS...SOME LIGHT SNOW COULD FALL ALONG THE ILLINOIS SHORE AT
TIMES. BUFKIT INDICATES MARGINAL TEMPERATURES BUT SHALLOW CLOUD
DEPTH...SO AM NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION...
PERHAPS A FEW TENTHS OF AN INCH IN NORTHWEST IN.
THE OTHER CONCERN IS TEMPERATURES. WITH CLEAR SKIES AWAY FROM THE
LAKE...LIGHT WINDS AND FRESH SNOWPACK...TEMPS COULD GET INTO THE
SINGLE DIGITS ACROSS THE NORTH SUBURBS WHERE SNOW COVER IS
DEEPEST. ALREADY SEEING SINGLE DIGITS AND LOW TEENS IN SRN WI AT
THIS HOUR.
ALLSOPP
//PREV DISCUSSION...
332 PM CST
MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LINGERING LAKE EFFECT
SNOW SHOWERS ACROSS NORTHWEST INDIANA TONIGHT INTO EARLY SUNDAY
MORNING...BUT OF MORE IMPORTANCE ARE THE INCREASED PROBABILITIES
FOR A SIGNIFICANT SNOW ACCUMULATION FOR A GOOD PORTION OF THE CWA
MONDAY NIGHT INTO TUESDAY NIGHT.
LATEST RADAR IMAGERY DEPICTING PERSISTENT LAKE EFFECT SNOW SHOWERS
FOR AREAS ACROSS NORTHEAST ILLINOIS AND NORTHWEST
INDIANA...PRIMARILY EAST OF INTERSTATE 57 LATE THIS AFTERNOON. A
MORE BROAD AREA OF LIGHT SNOW HAD DEVELOPED WITH A BETTER BAND
NOTED PUSHING SOUTH INTO LAKE/PORTER COUNTIES EARLIER TODAY.
VISIBILITY AND ISOLATED SLIPPERY CONDITIONS HAVE BEEN A CONCERN
BUT A SAVING GRACE HAS BEEN THE RELATIVELY WARMER CONDITIONS AT
AROUND FREEZING. THIS HAS ALLOWED FOR MOST OF THE MAJOR HIGHWAYS
TO REMAIN ONLY WET...PER TRAFFIC CAMS ACROSS NORTHWEST INDIANA.
ALTHOUGH IN THE NEAR TERM...HAVE NOTICED A DIMINISHING TREND WITH
THE OVERALL DEVELOPMENT AS WELL AS THE STRONGER MORE DEFINED BAND
IN INDIANA. THIS IS IN RESPONSE TO THE LOSS OF THE CONVERGENCE
ALONG THE SOUTHERN END OF THE LAKE AS WELL AS SOME MODERATING
THERMODYNAMIC CONDITIONS ACROSS THE ENTIRE LAKE. DONT FEEL AS IF
OUR CWA IS COMPLETELY THROUGH WITH OBSERVING SOME LAKE EFFECT SNOW
TONIGHT INTO SUNDAY MORNING DESPITE BOUNDARY LAYER FLOW SHIFTING
MORE NORTH/NORTHWEST THIS EVENING. COLDER AIR CURRENTLY WORKING
ITS WAY SOUTH DOWN THE LAKE WILL CONTINUE TONIGHT REINFORCING
DELTA TS OVER THE LENGTH OF THE LAKE. THIS COINCIDING WITH A LONG
FETCH AS WELL AS SHORT RANGE GUIDANCE INDICATING THAT BETTER LOW
LEVEL FORCING/CONVERGENCE WILL RETURN BACK TO THE CWA AFTER THE
9PM TIME FRAME TONIGHT...DO EXPECT REDEVELOPMENT OF SNOW SHOWERS
BUT PRIMARILY FOR LAKE AND PORTER COUNTIES IN INDIANA. SO HAVE
INCREASED POPS TONIGHT ACROSS THESE AREAS AND HAVE INCLUDED
ADDITIONAL SNOW ACCUMULATION OF A COUPLE OF INCHES...WHICH SEEMS
PROBABLE WITH COLDER TEMPS EXPECTED TONIGHT. THE REMAINDER OF THE
CWA WILL OBSERVE QUIET AND MOSTLY CLEAR SKIES TONIGHT...OUTSIDE OF
A FEW PASSING HIGH LEVEL CLOUDS. ALSO DO EXPECT A CHILLY NIGHT
WITH LOW TEMPS IN THE TEENS EXPECTED ACROSS MOST OF THE
CWA...OUTSIDE OF LAKE EFFECT CLOUD COVER IN NORTHWEST INDIANA.
FAIRLY SIMILAR CONDITIONS ARE EXPECTED ACROSS THE LAKE SUNDAY
MORNING...WITH LAKE EFFECT SNOW STILL AFFECTING PRIMARILY PORTER
COUNTY. DONT EXPECT MUCH IN TERMS OF ACCUMULATION AS BETTER
DEVELOPMENT SHOULD BE JUST EAST OF PORTER COUNTY...WITH BOUNDARY
LAYER FLOW CONTINUING TO SHIFT AND CONDITIONS OVER THE LAKE
BECOMING LESS FAVORABLE. SKIES WILL BE CLEARING FOR ALL OF THE CWA
ON SUNDAY AS VORT MAX SLIDES SOUTHEAST OF THE AREA AND RISING
HEIGHTS ALOFT USHER IN A SURFACE RIDGE. WITH A WARM MARCH SUN AND
A MODERATING TEMP PROFILE...RELATIVELY PLEASANT CONDITIONS IN THE
LOW TO MID 30S WILL BE OBSERVED. ALTHOUGH...DO EXPECT THIS TO BE
RATHER BRIEF AS FOCUS THEN SHIFTS TOWARDS THE APPROACHING SYSTEM
FOR THE START OF THE WEEK.
AS WAS MENTIONED ABOVE...AM GETTING A LITTLE MORE CONCERNED AT THE
POSSIBILITY FOR A SIGNIFICANT SNOWFALL ACROSS A PORTION OF THE CWA
MONDAY NIGHT INTO TUESDAY NIGHT. THE SYSTEM WHICH WE HAVE
CONTINUED TO MONITOR OVER THE LAST SEVERAL DAYS HAS STARTED TO
BECOME MORE CONSISTENT AMONG VARIOUS MODEL GUIDANCE. DESPITE THE
FACT THAT THERE ARE STILL SOME TIMING AND EXACT PLACEMENT
ISSUES...CONSENSUS IS GROWING FOR A STRONG SYSTEM TO AFFECT
NORTHERN ILLINOIS AND NORTHWEST INDIANA. A STRONG UPPER LEVEL
SYSTEM IS STILL FORECAST TO SLIDE ACROSS THE NORTHERN PLAINS BY
MONDAY...THEN QUICKLY DIG SOUTHEAST TOWARDS THE MID MISSISSIPPI
VALLEY MONDAY NIGHT INTO TUESDAY. WAA OUT AHEAD OF THIS SYSTEM
WILL SLOWLY BRING PRECIP ACROSS PRIMARILY THE SOUTHWEST PORTIONS
OF THE CWA DURING THE DAY ON MONDAY. WITH SLIGHT WARMING...A MIX
OF LIGHT RAIN OR SNOW WILL BE POSSIBLE FOR AREAS ACROSS THE
SOUTHERN CWA...BUT WITH LIGHT SNOW EXPECTED FURTHER NORTHWEST.
ALTHOUGH...REALLY NOT ANTICIPATING MUCH IN TERMS OF ANY
ACCUMULATION THROUGH MOST OF MONDAY WITH RELATIVELY WARMER TEMPS
IN PLACE. ITS NOT UNTIL LATE MONDAY NIGHT INTO TUESDAY THAT MORE
WIDESPREAD DEVELOPMENT WILL SHIFT EAST ACROSS THE CWA. DO EXPECT
ALL SNOW FOR THIS INITIAL TIME FRAME WITH LARGE SCALE LIFT RAPIDLY
COOLING THE TEMP PROFILE ACROSS THE AREA. LARGE SCALE FORCING
INCREASES...AND REALLY GETS GOING ON TUESDAY AS THIS UPPER LEVEL
LOW SHIFTS SOUTHEAST AND THE CWA LIKELY OBSERVES PERIODS OF
PERSISTENT WAA...WITH LIKELY AREAS OF DEFORMATION TO PIVOT ACROSS
THE CWA. ABUNDANT MOISTURE WILL BE PRESENT AND IS SEEN WITH THE
QPF THAT MODEL GUIDANCE IS DEVELOPING...WHICH SEEMS LIKE A VALID
SOLUTION GIVEN THE STRENGTH OF THIS DYNAMIC SYSTEM. WIDESPREAD
SNOW ACCUMULATION IS APPEARING MORE PROBABLE ACROSS THE ENTIRE CWA
TUESDAY INTO TUESDAY NIGHT AND AT THIS TIME...MORE SIGNIFICANT
SNOWFALL POSSIBLY IN EXCESS OF 6 INCHES IS PROBABLE FOR AREAS
SOUTH OF INTERSTATE 80. THIS SYSTEM WILL DEFINITELY NEED TO BE
MONITORED WITH SUCCESSIVE FORECASTS AS GUIDANCE COULD CONTINUE TO
VARY. NONETHELESS...IT IS APPEARING THAT THE REGION AND A PORTION
OF OUR AREA IN NORTHEAST ILLINOIS AND NORTHWEST INDIANA COULD
OBSERVE A SIGNIFICANT SNOW ACCUMULATION WITH WIDESPREAD IMPACTS
LATE MONDAY NIGHT INTO TUESDAY NIGHT. GIVEN THE TIME RANGE OF THE
EVENT AND POSSIBLE RANGE OF SOLUTIONS...HAVE HELD OFF ON ANY
HEADLINES BUT WILL CONTINUE TO MONITOR THIS POTENTIAL.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* NONE
BMD
//DISCUSSION...UPDATED 06Z...
QUIET VFR PERIOD EXPECTED THROUGH MONDAY NIGHT. A RIDGE AXIS LIES
JUST WEST OF THE MISSISSIPPI RIVER TONIGHT AND WILL SLOWLY
TRANSITION EAST AND WILL MOVE ACROSS THE CHICAGO AREA SUNDAY
EVENING. AS THIS OCCURS...LIGHT NORTHERLY WIND WILL PREVAIL WITH
MOSTLY CLEAR SKIES. THERE ARE SOME LAKE EFFECT CLOUDS AT THE
SOUTHERN END OF LAKE MICHIGAN BUT SHOULD STAY EAST OF GYY. ONCE THE
RIDGE AXIS SLIDES OVERHEAD...EXPECT WINDS TO BEGIN TO TREND TO
SOUTHEASTERLY SUNDAY NIGHT INTO EARLY MONDAY AS LOW PRESSURE TAKES
SHAPE OVER THE CENTRAL PLAINS. THERE MAY ALSO BE AN INCREASE IN MID
AND HIGH LEVEL CLOUDINESS TOWARDS THE END OF THE TAF PERIOD.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...INCREASING SNOW AND MVFR CHANCES MONDAY NIGHT.
TUESDAY...SNOW AND IFR LIKELY.
WEDNESDAY...LINGERING LIGHT SNOW/MVFR BECOMING VFR.
THURSDAY AND FRIDAY...VFR.
MDB
&&
.MARINE...
400 PM CST
NORTH WINDS WILL CONTINUE TO GRADUALLY DIMINISH TO A MODERATE
BREEZE TONIGHT AND SUNDAY AS A RIDGE OF HIGH PRESSURE EXTENDING
FROM HUDSON BAY TO THE SOUTHERN PLAINS MOVES SLOWLY EASTWARD...
REACHING LAKE SUPERIOR...EASTERN WISCONSIN AND ILLINOIS...AND
THE LOWER OHIO VALLEY BY SUNDAY NIGHT. LIGHT BREEZES WILL
INCREASE TO MODERATE NORTHEAST AND EAST BREEZES DURING MONDAY
AND MONDAY NIGHT AS LOW PRESSURE MOVES EAST ACROSS THE CENTRAL
PLAINS TO THE LOWER OHIO VALLEY. AS THE LOW CONTINUES MOVING
OFF TO THE EAST MONDAY NIGHT THROUGH WEDNESDAY WINDS ON LAKE MI
WILL BACK TO OUT OF THE NORTHEAST AND NORTH WHILE FRESHENING TO
STRONG BREEZES. DURING WEDNESDAY AND WEDNESDAY ANOTHER RIDGE OF
HIGH PRESSURE WILL BE MOVING EAST TO ONTARIO... THE UPPER GREAT
LAKES...AND THE MID AND LOWER MS VALLEY ALLOWING WINDS TO
GRADUALLY SLACKEN TO A LIGHT BREEZE AGAIN.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 10 PM SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM
SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1252 AM EST SUN MAR 3 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 400 PM EST SAT MAR 2 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OVER THE WRN CONUS AND
AND TROUGHING OVER THE EAST...RESULTING IN NW MID/UPPER LEVEL FLOW
FROM WRN CANADA THROUGH THE PLAINS INTO THE LOWER MS VALLEY. AT THE
SFC...A RIDGE EXTENDED FROM HUDSON BAY AN NW ONTARIO THROUGH WRN
LAKE SUPERIOR. DAYTIME MIXING AND LOW LEVEL DRYING UPSTREAM
(DEWPOINT DEPRESSIONS AOA 30F) HAS SUBSTANTIALLY REDUCED THE
COVERAGE/INTENSITY OF LES INTO N CNTRL UPPER MI THIS AFTERNOON.
TONIGHT...A WEAK SHORTWAVE TROUGH TO NEAR INL WILL DIVE SE
REINFORCING THE MID LEVEL TROUGH OVER THE NRN GREAT LAKES.
HOWEVER..THE SFC RIDGE EXTENDING SOUTH FROM THE HUDSON BAY HIGH WILL
CONTINUE TO BE THE DOMINANT FEATURE OVER THE AREA. INVERSION HEIGHTS
BETWEEN 2K TO 3K FT AND THE VERY DRY AIR UPSTREAM NORTH OF LAKE
SUPERIOR...WILL HELP SUPPRESS LAKE EFFECT SNOW CHANCES/INTENSITY
DESPITE TEMPS FCST NEAR -14C AT THE BASE OF THE INVERSION.
AS LAND BREEZES DEVELOP TONIGHT...INCREASING LOW LEVEL CONVERGENCE
SHOULD STRENGTHEN LES WITH SCT -SHSN INTO NORTH CENTRAL UPPER MI FROM
MARQUETTE TO MUNISING. ANY SNOWFALL AMOUNTS...HOWEVER SHOULD BE
LIGHT AMOUNTS OF A HALF INCH OR LESS. LAKE CLOUDS ARE EXPECTED TO
LIMIT TEMP FALL OVER CNTRL AND EAST PORTIONS OF THE CWA...BUT WITH
LIGHT/CALM WINDS AND SOME CLEARING INLAND WEST...TEMPS SHOULD DROP
INTO THE SINGLE DIGITS BLO ZERO...WITH SOME LOCALLY COLDER TEMPS
POSSIBLE.
SUNDAY...SIMILAR TO TODAY...EXPECT THAT LES IN THE MORNING MAINLY
INTO N CNTRL UPPER MI WILL DIMINISH IN THE AFTERNOON WITH THE SFC
RIDGE REMAINING OVER THE REGION. EXPECT MAX TEMPERATURES TO CLIMB
INTO THE MID AND UPPER 20S AS THE ARCTIC AIRMASS SLOWLY MODIFIES.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 400 PM EST SAT MAR 2 2013
TROUGH THAT HAS BEEN STUCK OVER THE GREAT LAKES THROUGH MOST OF THIS
PAST WEEK LOOKS TO FINALLY EASE BY MID-LATE WEEK. A MORE SIGNIFICANT
SHORTWAVE TROUGH DIGS INTO THE MEAN TROUGH MONDAY THROUGH WEDNESDAY.
BASED ON TRACK OF SHORTWAVE AND H85-H5 Q-VECTOR CONVERGENCE...MOST
OF THE SNOW FROM THAT SYSTEM WILL IMPACT MOST OF MINNESOTA THROUGH
WISCONSIN AND INTO LOWER MICHIGAN. EVEN THOUGH SFC-H85 LOWS REMAIN
WELL TO SOUTH OF UPR MICHIGAN...NORTHEAST WINDS BTWN THE LOWS AND
HIGH PRESSURE OVER HUDSON BAY AND ENOUGH LOW-LEVEL MOISTURE THROUGH
H9 ALONG WITH COLD ENOUGH TEMPS AT TOP OF INVERSION SHOULD SUPPORT
LIGHT LK EFFECT THROUGH WEDNESDAY BEFORE WINDS BECOME LIGHT AND
VARIABLE. SIMILAR TO WHAT WE HAVE SEEN LATELY THE SNOW WILL BE
AROUND BUT NOT ACCUMULATE MUCH AS INVERSION HEIGHTS REMAINING
BLO 3KFT LIMIT LK EFFECT INTENSITY AND MARGINALLY COLD AIR LIMITS
FLUXES OFF THE LAKES. INCREASING MOISTURE THROWN TO NORTH OF EARLY
WEEK LOW PRESSURE SYSTEM MAY HELP ENHANCE THE SNOW SLIGHTLY MONDAY
NIGHT AND TUESDAY IN AREAS FAVORED BY NORTHEAST WINDS. PERHAPS SOME
LIGHT SNOW ACCUMULATIONS OF A FEW INCHES MAY OCCUR DURING THAT TIME.
TEMPERATURES THROUGH WEDNESDAY WILL BE GRADUALLY WARMING...BUT STILL
ONLY INTO LOWER 30S. TRICKY FORECAST NIGHTTIME LOWS SUNDAY NIGHT AS
AREAS AWAY FROM THE CLOUDS AND SNOW SHOWERS NEAR LK SUPERIOR MAY
EASILY DROP BLO ZERO. MORE CLOUDS ON MONDAY NIGHT AND TUESDAY NIGHT
SHOULD RESULT IN READINGS STAYING MOSTLY IN THE TEENS ABOVE ZERO.
HIGH PRESSURE MOVING INTO THE AREA WEDNESDAY NIGHT WILL BEGIN TO
TURN WINDS TO THE SOUTH AND WILL FINALLY END LIGHT LK EFFECT BY
THURSDAY. BY FRIDAY...UPPER LEVEL TROUGH DEVELOPS FROM WESTERN
CONUS THROUGH NORTHERN PLAINS WHILE RIDGING MOVES ACROSS GREAT LAKES
IN WAKE OF THE EARLY WEEK SYSTEM. EXPECT LOW PRESSURE TO FORM ON
LEADING EDGE OF TROUGH OVER THE PLAINS...THOUGH THE STORM SHOULD NOT
BE TOO STRONG AS LOW-LEVEL TEMPERATURE CONTRAST PRECEEDING THE
SYSTEM IS MINIMAL. GFS AND ECMWF THEN SHOW TROUGH SPLITTING BY
FRIDAY WITH SOUTHERN STREAM PORTION CLOSING OFF OVER SOUTHWEST
CONUS WHILE NORTHERN BRANCH SHORTWAVE MOVES EAST ACROSS SOUTH
CENTRAL CANADA. NORTHERN TROUGH MOVING EAST WILL DRAG THE WEAKER LOW
PRESSURE SYSTEM AND ASSOCIATED COLD FRONT ACROSS GREAT LAKES LATER
ON FRIDAY. GFS REMAINS QUICKER WITH THIS COLD FROPA COMPARED TO
ECMWF AND GEM-NH. COULD BE SOME PRECIPITATION WITH THE SYSTEM...BUT
SINCE THE H85 LOW IS OPENING UP AND BECOMING MORE PROGRESSIVE...AND
MOVING THROUGH QUICKLY...DO NOT EXPECT SIGNIFICANT PRECIPITATION.
HAVING SMALL CHANCE POPS IN THERE FOR THURSDAY NIGHT THROUGH FRIDAY
NIGHT SEEM JUSTIFIED DURING THIS TIME FRAME.
AFTER THE PERSISTENT TROUGHING KEEPS TEMPS ON THE COOLER SIDE OF
AVERAGE TO START THE WEEK...EXPECT WARMER READINGS THURSDAY INTO
FRIDAY WITH SOUTH-SOUTHWEST WINDS BTWN THE HIGH PRESSURE AND THE LOW
PRESSURE SYSTEM TO THE WEST. BASED ON 925-900MB TEMPS...SHOULD SEE
HIGHS ON THURSDAY REACH THE 30S WITH JUST A SMALL DROP IN READINGS
ON THURSDAY NIGHT IN WARM AIR ADVECTION AHEAD OF THE COLD FRONT.
TEMPERATURES ON FRIDAY PROBABLY REACH WELL INTO THE 30S. IF NOT FOR
A MOSTLY CLOUDY SKY...COULD EVEN SEE A FEW LOW-MID 40S WHERE MIXING
IS STRONGER. DID TWEAK TEMPS UPWARD NEAR LK SUPERIOR WITH DOWNSLOPE
WINDS FCST. TIGHTER PRESSURE GRADIENT WILL LEAD TO BREEZY CONDITIONS
THURSDAY NIGHT AND FRIDAY. TURNING BLUSTERY FOR SATURDAY FOLLOWING
THE COLD FRONT PASSAGE. TEMPS WILL NOT DROP TOO MUCH THOUGH...MAINLY
STAYING IN THE LOW-MID 30S...WHICH IS NEAR NORMAL FOR EARLY MARCH.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1250 AM EST SUN MAR 3 2013
DIFFICULT FORECAST CONTINUES WITH OFF AND ON AGAIN LAKE EFFECT
CLOUDS WITH NORTHERLY UPSLOPE DIRECTION CONTINUING. EACH
DAY...DIURNAL HEATING HAS MIXED OUT THE MVFR DECK WITH SOME DRIER
AIR. PERSISTENCE WITH THIS THEME WILL CONTINUE AT SAW AND CMX. VFR
CONDITIONS OVERNIGHT WILL BE REPLACED WITH THE MVFR CLOUDS
LATE TONIGHT AND THIS WILL LAST INTO SUN AFTERNOON BEFORE HEATING
AND MIXING AGAIN MIXES THIS LOW DECK BACK OUT. VFR CONDITIONS WILL
CONTINUE AT IWD THROUGH THE PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 400 PM EST SAT MAR 2 2013
WINDS LESS THAN 20 KTS THROUGH MONDAY...THEN EXPECT NORTHEAST WINDS
TO INCREASE TO 30 KTS OVER WESTERN SECTIONS BY MONDAY NIGHT AS LOW
PRESSURE SYSTEM MOVES BY TO THE SOUTH OVER THE NORTHERN MISSISSIPPI
RIVER VALLEY. WINDS 20-30 KTS CONTINUE OVER MOST OF LK SUPERIOR
THROUGH TUESDAY BEFORE SETTLING DOWN TO LESS 20 KTS BY WEDNESDAY.
WINDS INCREASE TO 25 KTS FROM THE SOUTH THURSDAY NIGHT AND FRIDAY
AHEAD OF COLD FRONT. NO GALES ARE EXPECTED THIS WEEK...THOUGH COULD
SEE GALE GUSTS OVER WESTERN LK SUPERIOR MONDAY NIGHT CLOSER TO
MINNESOTA SHORELINE DUE TO COASTAL CONVERGENCE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...07
MARINE...JLA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
344 AM CST SUN MAR 3 2013
.SHORT TERM...TODAY THROUGH MONDAY NIGHT...
THE HIGHLIGHTS OF THE SHORT TERM ARE A SIGNIFICANT WINTER STORM
TODAY THROUGH MONDAY NIGHT AND DENSE FOG NORTH CENTRAL THIS MORNING.
DID EXTEND THE ONGOING DENSE FOG ADVISORY FOR THE TURTLE MOUNTAINS
AREA AND THE FAR UPPER JAMES RIVER VALLEY THROUGH 15 UTC AS THE
LATEST RUNS OF THE HRRR SUGGEST THE DENSE FOG WILL CONTINUE PAST
12 UTC. THIS SEEMS PLAUSIBLE GIVEN THE MOIST LOW LEVELS AHEAD OF
THE STORM AND WEAK MIXING THIS MORNING.
IN REGARDS TO THE WINTER STORM...THE 00 UTC DETERMINISTIC SUITE IS
IN GOOD AGREEMENT...AND USED A BLEND OF THE GFS/ECMWF/GEM/SREF FOR
ALL FIELDS THROUGH MONDAY NIGHT...WITH THE NAM EXCLUDED AS IT IS A
NORTHERLY OUTLIER WITH THE UPPER LEVEL LOW. LOW LEVEL ISENTROPIC
LIFT AND COUPLING OF FRONTOGENETIC AND UPPER LEVEL FORCING INCREASE
THROUGH LATE SUNDAY MORNING AND THE AFTERNOON. THUS...EXPECT TO
SEE A SLOW INCREASE IN PRECIPITATION THROUGH SUNDAY MORNING AND
INTO THE AFTERNOON. PRECIPITATION IS EXPECTED TO BEGIN AS ALL RAIN
ACROSS THE SOUTHWEST WITH ABOVE FREEZING TEMPERATURES THROUGH
APPROXIMATELY 800 MB. THE PREFERRED ZONE OF MIXED PHASE
PRECIPITATION FROM WILLISTON THROUGH BISMARCK AND WISHEK LATE
THIS MORNING AND EARLY AFTERNOON WILL SHIFT SOUTHWEST THROUGH THE
LATE AFTERNOON AND EARLY EVENING AS DYNAMIC COOLING AIDES IN
ERODING THE WARM LAYER ALOFT. THE AREA OF GREATEST CONCERN FOR
ICE ACCUMULATIONS...UP TO A TENTH OF AN INCH...IS FROM WATFORD
CITY THROUGH HEBRON AND FORT YATES WHERE THE WINDOW OF A WARM
LAYER NEAR +3 C RESIDES ABOVE SUB FREEZING SURFACE TEMPERATURES
THE LONGEST.
CONTINUED COUPLING OF LOW LEVEL AND UPPER LEVEL CIRCULATIONS
CONTINUE SUNDAY EVENING AND INTO MONDAY MORNING...WITH STRONG
OMEGA IN THE DENDRITIC GROWTH ZONE. A TEMPORARY LULL IN THE STORM
IS EXPECTED LATE SUNDAY NIGHT INTO MONDAY MORNING ACROSS THE
SOUTHWEST AND SOUTH CENTRAL AS A DRY SLOT WORKS INTO THE
AREA...WHICH WILL ACT AS A LIMITING FACTOR FOR HIGHER SNOWFALL
ACCUMULATIONS. SNOW ASSOCIATED WITH THE TROWAL CONTINUES MONDAY
AFTERNOON...WITH INTENSITIES DECREASING INTO MONDAY NIGHT. COLD
AIR ADVECTION ON THE BACKSIDE OF THE SYSTEM ON MONDAY SUPPORTS
MOMENTUM TRANSPORT WITH GUSTS OF 30-35 KTS POSSIBLE WEST OF
HIGHWAY 83. WILL HAVE TO MONITOR THIS AS BLIZZARD CONDITIONS COULD
BE APPROACHED. SEE THE WSW FOR SNOWFALL ACCUMULATION DETAILS...BUT
IN GENERAL...THE GREATEST SNOWFALL AMOUNTS OF 12 TO 15 INCHES ARE
FORECAST FOR THE FAR NORTHWEST AND NORTH CENTRAL...DECREASING TO 6
TO 8 INCHES SOUTH CENTRAL WITH 3 TO 5 OR LESS FOR THE SOUTHWEST.
.LONG TERM...TUESDAY THROUGH SATURDAY NIGHT...
NO SIGNIFICANT HIGHLIGHTS IN THE EXTENDED PERIOD.
FOLLOWING THE WINTER STORM SUNDAY THROUGH MONDAY NIGHT...EXPECT A
COOL DAY TUESDAY WITH HIGHS OF 15 TO 20 ALONG AND EAST OF THE
MISSOURI RIVER AND 20 TO 30 SOUTHWEST. AFTER THAT...AN UPPER LEVEL
RIDGE WILL BUILD EAST ACROSS THE NORTHERN PLAINS. MILD AND DRY
WEATHER WILL RETURN TO THE FORECAST AREA WEDNESDAY.
TEMPERATURES WILL BE NEAR OR SLIGHTLY WARMER THAN NORMAL...WITH
AFTERNOON HIGHS GENERALLY IN THE 20S AND 30S WEDNESDAY.
MEANWHILE A LONGWAVE TROUGH MOVES INTO THE WEST COAST WEDNESDAY AND
EXPANDS EASTWARD...RESULTING IN SOUTHWEST FLOW ALOFT OVER THE
NORTHERN PLAINS WITH SOME UPPER LEVEL ENERGY IMPULSES REACHING NORTH
DAKOTA ON THURSDAY. AT THE SAME TIME A SURFACE COLD FRONT MOVES
SOUTHWARD THROUGH THE STATE THURSDAY. THUS A CHANCE OF LIGHT SNOW
FOR THURSDAY AND THURSDAY NIGHT WITH LOWS THURSDAY NIGHT FROM 10 TO
20 DEGREES.
THE MEDIUM RANGE MODELS INDICATE THE LONGWAVE TROUGH CUTTING OFF
OVER THE SOUTHERN ROCKIES AND DESERT SOUTHWEST. THIS WOULD BRING A
PERIOD OF DRY WEATHER FOR NORTH DAKOTA FOR FRIDAY AND SATURDAY.
HOWEVER...WILL HAVE TO WATCH IN LATER MODEL RUNS TO SEE HOW THE
MODELS HANDLE THE CUTOFF SYSTEM. FOR NOW WILL KEEP THE FORECAST DRY
FOR FRIDAY AND SATURDAY WITH A WARMING TREND WITH HIGHS SATURDAY
MAINLY IN THE 30S AND 40S.
&&
.AVIATION...
A SURFACE LOW WAS OVER SOUTHERN ALBERTA AND A TROUGH EXTENDED FROM
THE LOW ACROSS EASTERN MONTANA TO ANOTHER LOW OVER EASTERN WYOMING
TO NORTHWESTERN SOUTH DAKOTA. VFR CIGS AND VSBYS MAINLY ALONG AND
SOUTH/WEST OF THE MISSOURI RIVER AT KDIK/KHEI/KISN/KBIS IN THE WARM
SECTOR WITH TEMPERATURES IN THE UPPER 20S TO 30S. EAST OF THE
MISSOURI IN THE COLDER SURFACE AIR WITH TEMPERATURES IN THE TEENS TO
LOWER 20S AT KMOT/KDVL IFR/LIFR CIGS AND VSBYS HAD DEVELOPED.
RUGBY/ROLLA/HARVEY ALSO LIFR...AND EXPECT KJMS TO BECOME IFR BEFORE
12Z.
AS THE STORM SYSTEM CONTINUES TO DEVELOP AND APPROACH NORTH
DAKOTA...CIGS WILL LOWER AT TAF SITES. A LIGHT WINTRY MIX WILL
BEGIN TO IMPACT KISN/KBIS/KMOT AFTER 12Z...WITH LIGHT RAIN FOR
KDIK/KHEI. PRECIPITATION WILL SPREAD EAST INTO KMOT AFTER 15Z AND
KJMS AFTER 18Z. A GRADUAL TRANSITION FROM A LIGHT WINTRY MIX/RAIN
TO MAINLY SNOW AND LOWERED VISIBILITIES TO IFR/LIFR WILL BE SEEN
AFTER 18Z FOR KBIS/KISN/KMOT/KJMS...WITH KDIK TRANSITIONING TO ALL
SNOW BETWEEN 21Z AND 00Z.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM NOON TODAY TO 6 AM CST TUESDAY FOR
NDZ001>005-009>013-017>023-025-034>037-046>048-050-051.
WINTER WEATHER ADVISORY FROM NOON CST /11 AM MST/ TODAY TO 6 AM
CST /5 AM MST/ TUESDAY FOR NDZ031>033-041-042-045.
DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR NDZ004-005-
012-013-022-023-025.
&&
$$
SHORT TERM...AYD
LONG TERM/AVIATION...JV
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
420 AM EST SUN MAR 3 2013
.SYNOPSIS...
STUBBORN UPPER LEVEL LOW CONTINUES TO BRING UPSLOPE SNOW SHOWERS
INTO SUNDAY. HIGH PRESSURE CROSSES MONDAY. ANOTHER LOW PRESSURE
SYSTEM CROSSES TUESDAY THROUGH WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
BROAD UPPER TROUGH CONTINUES TO SPIN OVER THE NORTHEAST CONUS...WITH
ANOTHER DISTURBANCE ROTATING AROUND ITS BACKSIDE FROM NW TO SE TODAY.
12Z THIS MORNING AFOREMENTIONED UPPER LOW OVER NORTHEAST CENTERED
ROUGHLY OVER THE NYC AREA BUT WILL FINALLY BEGIN A SLOW EXODUS TO
THE EAST...PROGGED TO BE JUST SOUTH OF CAPE COD MASS BY 00Z SUN. AS
IT DOES SO...ONE FINAL S/W TROUGH WILL QUICKLY DROP SSE-WARD WITH
AXIS OVER WESTERN OHIO BY 18Z AND NEAR THE OHIO RIVER BY 00Z SUN.
LATEST NAM 03.00 RUN IN FACT ATTEMPTS TO BRIEFLY CLOSE THIS 500MB
LOW OFF BY THIS TIME. LARGE SCALE ASCENT PUSHES INTO THE WESTERN
ZONES BY 12Z AND IS MAXIMIZED OVER THE SOUTHERN ZONES AROUND 18Z. IN
ADDITION...A DECENT AREA OF POTENTIAL VORT ADVECTION PUSHES ACROSS
THE AREA AS WELL BTWN 18Z SAT AND 00Z SUN. AS WITH
YESTERDAY...AMOUNT OF LLVL MOISTURE IS SOMEWHAT IN QUESTION PER NAM
SOUNDINGS. RUC SOUNDINGS HOWEVER INDICATE A DEEPER SATURATED LLVL AS
IT DID YESTERDAY. WITH THIS IN MIND...EXPECT A DAY FAIRLY SIMILAR TO
YESTERDAY WITH OFF/ON FLURRIES AND SNOW SHOWERS. AS SUCH...WILL KEEP
AT LEAST SLIGHT CHANCE POPS GOING FOR THE AREA FOR MUCH OF THE
DAY...WITH THE USUAL HIGHER CHANCE POPS IN THE EASTERN HIGH COUNTRY.
ALSO LOWERED MAX TEMPS A BIT. DEPENDING ON MODEL OF CHOICE...925MB
TEMPS IDENTICAL OR A BIT COOLER THIS AFTERNOON VERSUS YESTERDAY AND
WITH THE EXPECTED CLOUD COVER AND FLURRIES AND/OR LIGHT SNOW
AROUND...TEMPS SHOULD BE ABOUT IDENTICAL TO YESTERDAY/S READINGS.
BY 00Z SUN TROUGH AXIS/POSSIBLE CUT OFF LOW NEAR THE OHIO RIVER WITH
THE LARGE SCALE FORCING FOR ASCENT EAST OF IT BUT EXITING THE
AREA...WHICH SHOULD EFFECTIVELY END PRECIP CHANCES FOR LOWLAND
LOCATIONS. TRAPPED LLVL MOISTURE IN THE USUAL FAVORED UPSLOPE AREAS
OF THE NORTHEAST MOUNTAINS SHOULD SEE AN INCREASE IN SNOWFALL
ACTIVITY DURING THE EVENING HOURS AS TROUGH WITH ASSOC LIFT MAKES
ITS WAY THROUGH. 850MB WIND TRAJECTORY OFF LAKE ERIE NOT THE BEST
BUT PRESENT NONETHELESS OFF THE WESTERN TIP. ANTICIPATE A GENERAL
INCH TO TWO INCHES FOR THIS AREA WITH LESSER AMOUNTS IN THE
VALLEYS...WITH THE SNOWFALL TAPERING OFF BY THE END OF THE PERIOD.
ACROSS THE LOWLANDS CLOUDS INTO THE OVERNIGHT HOURS WILL GIVE WAY TO
SOME PARTIAL CLEARING IN THE LATE HOURS TOWARDS DAWN. GIVEN THE
RELATIVELY LOW MAX TEMPS TODAY WITH LIGHT WINDS AND DEWPTS INTO THE
UPPER TEENS...LOWLAND MINS SHOULD HAVE NO TROUBLE FALLING TO AROUND
THE 20 DEGREE MARK BY DAWN MONDAY.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
COULD STILL BE A FEW LINGERING UPSLOPE SNOW SHOWERS OR FLURRIES
ACROSS MOUNTAIN ZONES LATE SUNDAY NIGHT...BUT FOR THE MOST
PART...ANY LINGERING PRECIPITATION WILL TAPER OFF AS ATMOSPHERE
CONTINUES TO DRY OUT AS SURFACE HIGH BUILDS INTO THE REGION
TEMPORARILY. AS IT DOES SO...WILL SEE A GRADUAL CLEARING OF SKY
COVER SUNDAY NIGHT INTO EARLY MONDAY...AND WITH THE SURFACE HIGH
OVERHEAD...WILL SEE A NIGHT OF GOOD RADIATIONAL COOLING...DEPENDING
ON THE AMOUNT OF CLEARING THAT IS ABLE TO TAKE PLACE. WITH 850MB
TEMPS SUNDAY NIGHT/EARLY MONDAY DIPPING TO AROUND -13C...EXPECT MANY
MOUNTAINOUS LOCATIONS TO DIP INTO THE SINGLE DIGITS TO LOWER
TEENS...WITH TEENS TO LOWER 20S ACROSS THE LOWLANDS.
SHORTWAVE RIDGING WILL THEN GRADUALLY BUILD ACROSS THE AREA FOR
MONDAY INTO TUESDAY OUT AHEAD OF THE NEXT LOW PRESSURE
SYSTEM...WHICH WILL PUSH A WARM FRONTAL BOUNDARY INTO THE CWA IN THE
MONDAY NIGHT THROUGH TUESDAY TIME FRAME. EXPECT A GRADUAL WARM UP IN
TEMPERATURES AS COMPARED TO RECENT DAYS ON MONDAY AND TUESDAY...WITH
PRECIPITATION GRADUALLY SPREADING INTO THE CWA BY EARLY TUESDAY.
DEPENDING ON THE TIMING AND EXACT TRACK OF THE LOW...COULD SEE
PRECIPITATION START OFF AS A WINTRY MIX ACROSS LOWLANDS...BEFORE
CHANGING TO RAIN AS THE DAY PROGRESSES. HIGHER ELEVATIONS WILL STAY
PREDOMINATELY SNOW OR A MIX THROUGHOUT THE DAY. IN ADDITION...MODELS
INDICATING SOME WEAK INSTABILITY ACROSS EXTREME SOUTHERN ZONES...AND
AS A RESULT...ELECTED TO ADD IN A SLIGHT CHANCE OF THUNDER INTO THE
FORECAST FOR TUESDAY AFTERNOON...MAINLY IN SW VA ZONES. STILL A FEW
ISSUES WITH TIMING AND EXACT TRACK WITH THIS SYSTEM HOWEVER...AS IS
TO BE EXPECTED. THEREFORE...STILL A BIT OF AN ISSUE CONCERNING
PRECIPITATION TYPE EARLY IN THE PERIOD...COULD BE EITHER RAIN OR
SNOW...OR EVEN SLEET AT TIMES. FOR NOW...RAN JUST A RAIN/SNOW MIX OR
SNOW SCENARIO DUE TO THE UNCERTAINTY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
THE MARCH LION WILL BE ROAMING OUR AREA EARLY IN THE EXTENDED. THE
AMERICAN MODELS CONTINUE TO BE A BIT FASTER WITH THE CLOSED 500 MB
LOW MOVING EAST...OUT OF THE MID MISSISSIPPI VALLEY OR LOWER OHIO
VALLEY ON TUESDAY EVENING...COMPARED TO THE ECMWF. BUT THE 12Z
ECMWF SEEMS TO BE CATCHING UP.
ALL THE MODELS CONTINUE TO AGREE...THE 500 MB LOW PASSES TO OUR
SOUTH...PROBABLY OVER THE SMOKY MOUNTAINS AROUND 12 WEDNESDAY...
THEN NEAR THE NC OUTER BANKS AT 00Z THURSDAY. PICTURING THIS SYSTEM
TO BE STRONG ENOUGH TO BACK THE 700 MB FLOW AND THROW THE DEEPER
MOISTURE W/NW AS THE COLUMN COOLS LATE TUESDAY NIGHT AND EARLY
WEDNESDAY MORNING. AS A RESULT...FORECASTING THE POSSIBILITY OF
HEAVY WET SNOW OVER THE MOUNTAINOUS COUNTIES...ESPECIALLY WV
MOUNTAIN COUNTIES. HAVE INTRODUCED A HAZARD IN OUR HAZARDOUS
WEATHER POTENTIAL...FOR HEAVY WET SNOW...WATCH/WARNING STUFF FOR THE
WV MOUNTAIN COUNTIES...INCLUDING THE BKW/EKN VCNTY. EVEN...THE
LOWLAND COUNTIES COULD HAVE SOME LESSER ACCUMULATIONS WITH SOME
ADVISORIES.
WILL LEAVE HIGHER POPS LONGER THAN GUIDANCE AND PREVIOUS FORECAST
FOR WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING...BUT A STRONG POP
GRADIENT OVER THE OHIO VALLEY COUNTIES.
THE MARCH ENVIRONMENT FINALLY SETTLES DOWN FOR THURSDAY INTO
SATURDAY. A WEAK FEATURE MAY SAG DOWN FROM THE NORTH ON SATURDAY
AFTERNOON AND NIGHT.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
PREDOMINANTLY MVFR CIGS PREVAIL IN THE CONTINUED W TO NW FLOW OF
COLD AIR...WITH OCCASIONAL LOW VFR CIGS OVERNIGHT. IFR CIGS
EXPECTED TO BECOME MORE PREVALENT LATE OVERNIGHT THROUGH DAWN
SUNDAY. VSBY RESTRICTIONS IN SCATTERED SNOW SHOWERS WILL TEND TO
BECOME MORE CONFINED TO THE MOUNTAINS OVERNIGHT WITH MVFR
INTERSPERSED WITH BRIEF IFR IN A HEAVIER SNOW SHOWER.
SUNDAY WILL BRING MODEST IMPROVEMENT WITH STRATOCU CIGS GETTING TO
VFR BY AFTERNOON FOR LOWLAND LOCATIONS...WITH EASTERN MOUNTAIN
LOCATIONS REMAINING MVFR. EXPECT SNOW SHOWERS IN THE MOUNTAINS TO
WIND DOWN SOMEWHAT BY MIDDAY BUT PICK UP ONCE AGAIN BY AND AFTER
00Z MON.
LIGHT W TO NW SFC FLOW WITH LIGHT TO MODERATE NW FLOW ALOFT CONTINUES
THROUGH THE PERIOD.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z MONDAY...
FORECAST CONFIDENCE...MEDIUM.
ALTERNATE SCENARIOS: TIMING OF SNOW AND ASSOCIATED RESTRICTIONS MAY
VARY. TIMING OF CEILING CATEGORY CHANGES MAY ALSO VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE SUN 03/03/13
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
CRW CONSISTENCY H H H H M H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY M M M M M M L L M H H H
EKN CONSISTENCY M M M L L L L L L L L L
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY L L L L L L L L L L H H
AFTER 06Z MONDAY...
IFR VISIBILITIES AND CEILINGS POSSIBLE IN RAIN/SNOW TUESDAY THROUGH
WEDNESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/50
NEAR TERM...50
SHORT TERM...ARJ
LONG TERM...KTB
AVIATION...50
AREA FORECAST DISCUSSION
NWS PORTLAND OR
910 PM PST SAT MAR 2 2013
.SYNOPSIS...A SHARP COLD FRONT HAS MOVED ACROSS THE INTERSTATE 5
CORRIDOR AND IS NOW MOVING INTO THE CASCADES THIS EVENING. THIS FRONT
IS PRODUCING SOME RAIN...BUT THE MORE NOTABLE EFFECT IS A SHARP DROP
IN TEMPERATURE AND LOWERING SNOW LEVELS. SHOWERS WILL DECREASE LATER
TONIGHT AND EARLY SUNDAY...WITH JUST SOME ISOLATED SHOWERS IN THE
HIGHER TERRAIN BY SUNDAY AFTERNOON. OTHERWISE MOST AREAS WILL BEGIN
TO DRY OUT AS COOL HIGH PRESSURE BUILDS IN FOR SUNDAY NIGHT AND
MONDAY. BROAD LOW PRESSURE FROM THE GULF OF ALASKA IS EXPECTED TO CUT
OFF FROM THE MAIN FLOW AND LINGER NEAR THE OREGON COAST...RESULTING
IN UNSETTLED WEATHER FOR THE MIDWEEK PERIOD.
&&
.SHORT TERM...TODAY THROUGH TUESDAY...A SHARP COLD FRONT BY WEST
COAST STANDARDS IS MOVING ACROSS THE WASHINGTON AND OREGON THIS
EVENING. AS THE FRONT MOVED THROUGH THE PORTLAND METRO IT WAS
ACCOMPANIED BY THE TEXTBOOK SHARP WIND SHIFT FROM SOUTH AHEAD OF THE
FRONT TO NORTHWEST BEHIND THE FRONT. TEMPS/DEWPOINTS TUMBLED ABOUT 5
DEGREES ALMOST IMMEDIATELY WITH THE PASSAGE OF THE FRONT. ANYWHERE
EAST OF THE ROCKIES THIS WOULD NOT BE CONSIDERED TOO SIGNIFICANT...
BUT HERE ON THE WEST COAST IT IS NOT TOO COMMON TO SEE THIS TYPE OF
TEXTBOOK COLD FRONT. THE FREEZING LEVEL HAS FALLEN FROM 9000 FT THIS
MORNING TO 2000-3000 FT BEHIND THE FRONT...ABERNATHY MTN RAWS AT 2000
FT ELEVATION IN NW COWLITZ COUNTY WAS 33 DEGREES AS OF 8 PM. IT IS
LIKELY SNOW IS BEGINNING TO MIX WITH RAIN IN SCATTERED SHOWERS ABOVE
1500-2000 FT IN THE COAST RANGE.
WHAT THE COLD FRONT HAD IN TEMPERATURE AND DEWPOINT GRADIENT...IT DID
NOT HAVE IN IMPRESSIVE MOISTURE. THE UPPER DYNAMICS ASSOCIATED WITH
THIS SYSTEM WERE QUITE DISORGANIZED AS THE FRONT CAME IN. BASICALLY
THE FRONT ONLY HAD SURFACE MOISTURE AND LIFT TO WORK WITH...SO MOST
LOCATIONS STRUGGLED TO PICK UP MORE THAN 0.10 INCH. SOME SPOTS IN THE
EAST METRO...INCLUDING OUR OFFICE IN PARKROSE... HAD A LITTLE MORE
WITH A QUICK 0.20 INCH IN THE BUCKET SINCE 4 PM. WITH SHOWERS
DECREASING QUICKLY IN THE COLDER AIR IT APPEARS ANY SNOW
ACCUMULATIONS ABOVE 1500-2000 FT SHOULD BE LIGHT AND SPOTTY. THE BEST
CHANCE FOR A COUPLE INCHES WILL BE ABOVE 3000 FT.
UPPER DYNAMICS ARE ALREADY STARTING TO FOCUS EAST OF THE CASCADES AS
AN UPPER LOW PUSHES SOUTHEAST FROM BRITISH COLUMBIA INTO THE ROCKIES.
MEANWHILE LATEST RAP ANALYSIS SHOWS 700 MB TEMPS ALREADY WARMING WEST
OF 127-128W...CAPPING OFF ANY WEAK INSTABILITY OFFSHORE. IT IS QUITE
LIKELY SHOWERS WILL END FOR MOST BY SUNRISE SUNDAY...WITH THE BEST
CHANCE FOR LINGERING CLOUDS AND SHOWERS IN THE NORTH AND IN THE
HIGHER TERRAIN OF OUR FORECAST AREA.
HIGH PRESSURE BUILDS IN LATER SUNDAY FOR A MAINLY CLEAR AND CHILLY
NIGHT. THE EXCEPTION WILL BE SOME PATCHY VALLEY FOG IN THE TYPICAL
FOG PRONE AREAS. TEMPERATURES MAY FALL BELOW FREEZING IN MOST
OUTLYING VALLEYS...POSSIBLY FLIRTING WITH 32F EVEN AT KPDX. OFFSHORE
FLOW LIKELY MAKES MONDAY A MOSTLY SUNNY AND SEASONABLE DAY.
AN UPPER LOW CURRENTLY TRAVERSING THE ALEUTIANS IS PROGGED TO MOVE
ACROSS THE GULF OF ALASKA AND SETTLE AS A CUTOFF LOW SOMEWHERE OFF
THE OREGON OR NORTHERN CALIFORNIA COAST MONDAY NIGHT AND TUESDAY. AS
WITH MOST CUTOFF LOWS THERE IS A LOT OF UNCERTAINTY IN THE PACE AND
TRACK OF THIS SYSTEM AND ITS ASSOCIATED FRONT. 00Z NAM CONTINUES TO
BE THE FASTEST MODEL SPREADING RAIN ONSHORE MON NIGHT...WHILE THE
GFS/ECMWF/GEM CONSENSUS IS ABOUT 6-12 HOURS SLOWER. DEPENDING ON THE
TIMING...THERE IS AN OUTSIDE CHANCE OF SOME SNOW/ICE ISSUES IN THE
HOOD RIVER VALLEY DUE TO COLD AIR LEFT BEHIND BY OUR CURRENT SYSTEM.
THE LAST COUPLE NAM BUFR SOUNDINGS HAVE SUGGESTED SNOW AT LEAST FOR
THE UPPER HOOD RIVER VALLEY TUE MORNING. WILL NEED TO WATCH THIS...
OTHERWISE JUST EXPECT AN INCREASING CHANCE OF RAIN AND MOUNTAIN SNOW
TUESDAY. WEAGLE
.LONG TERM...TUESDAY EVENING THROUGH SATURDAY...AN UPPER LEVEL
CLOSED LOW IS PROGGED TO APPROACH THE OR COAST ON TUE...PUSHING AN
OCCLUDED FRONT THROUGH THE REGION DURING THE DAY TUE. EXPECT STEADY
RAIN WITH THE FRONT...THEN A TRANSITION TO SHOWERY WEATHER TUE NIGHT
AND WED AS THE LOW PUSHES SLOWLY INLAND. THE ATMOSPHERE WILL BE
FAIRLY UNSTABLE...AND A COLD AIRMASS ASSOCIATED WITH THE LOW MAY
ALLOW HEAVIER SHOWERS TO FALL AS SNOW DOWN INTO THE FOOTHILLS AND
COAST RANGE...BUT LITTLE SIGNIFICANT IMPACT IS EXPECTED. DUE TO THE
INSTABILITY WE DECIDED TO ADD A SLIGHT CHANCE OF THUNDER TO THE COAST
AND ADJACENT WATERS TUE AFTERNOON THRU WEDNESDAY. SHOWER
ACTIVITY SHOULD TAPER OFF WED NIGHT INTO THU AS THE LOW PUSHES EAST
INTO THE GREAT BASIN. DRIER WEATHER IS EXPECTED TO DEVELOP FOR THE
END OF THE WEEK AND INTO THE WEEKEND AS A PERIOD OF SHORTWAVE
RIDGING BUILDS INTO THE PAC NW. PYLE/BROWN/WEAGLE
&&
.AVIATION...COLD FRONT HAS CLEARED THE NORTH INTERIOR AND PUSHED
INTO THE CASCADES. THE FRONT SLOPES BACK TO THE SOUTHWEST...THUS
IT SHOULD BE ENTERING THE SOUTH VALLEY SOON. MOSTLY VFR CONDITIONS
EXIST WITH A FEW POCKETS OF MVFR. EXPECT CLOUDS TO BREAK UP SOME
OVERNIGHT. SEEMS REASONABLE THAT STRATUS OR FOG IS
POSSIBLE...THOUGH FEEL MVFR STRATUS HAS A BETTER CHANCE GIVEN THE
POST FRONTAL UNSTABLE AIR MASS. NOT MUCH IN THE WAY OF SHOWER
ACTIVITY OFFSHORE...THOUGH CANNOT RULE OUT A FEW FOR THE NORTHERN
TIER. ANY LOW CLOUD THAT FORMS DOES NOT LOOK LIKE IT WILL LAST
BEYOND THE MORNING.
KPDX AND APPROACHES...VFR CONDITIONS HAVE RETURNED TO THE
TERMINAL...WITH THE BULK OF THE PRECIPITATION CONFINED TO EAST
APPROACHES. WITH CLEARING SKIES OVERNIGHT AND WINDS EASING...HAVE
THE POTENTIAL OF FORMING STRATUS AFTER 10Z. CURRENT GUIDANCE
SUGGESTS MVFR...TOUGH TO SAY HOW LOW AT THIS POINT. ROCKEY/KMD
&&
.MARINE...COLD FRONT HAS PUSHED ONSHORE. STRONGEST GRADIENT LIES
ALONG THE NORTHERN WATERS THIS EVENING...THUS W TO NW WINDS
GUSTING AROUND 25 KT EASING TOWARDS MIDNIGHT. SEAS NOT CHANGING
MUCH...GENERALLY 9 TO 11 FT. ENP GUIDANCE IS RUNNING A TOUCH
HIGH.
HIGH PRESSURE BUILDS IN SUNDAY...AND PUSHES INLAND SUN NIGHT. THIS
WILL ALLOW OFFSHORE FLOW TO DEVELOP AHEAD OF THE NEXT SYSTEM
DROPPING SOUTH FROM THE GULF OF ALASKA EARLY IN THE WEEK. AS IT
APPROACHES...EXPECT SEAS TO RISE BACK INTO THE LOWER TEENS LATE
MONDAY OR EARLY TUESDAY...WHILE WIND GUSTS MAY APPROACH NEAR GALE
FORCE LATER MON INTO MON EVENING. THE LOW THEN MOVES OVER THE
WATERS RESULTING IN LIGHTER WINDS...THOUGH A SHOWERY AND UNSTABLE
AIRMASS WILL RESULT IN ERRATIC GUSTY WINDS AT TIMES. KMD
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL MIDNIGHT PST TONIGHT FOR
COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR
OUT 60 NM.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 PM PST SUNDAY
FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR
OUT 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 7 AM PST
SUNDAY.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 5 PM TO
11 PM PST SUNDAY.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1048 PM EST SAT MAR 2 2013
.SYNOPSIS...
A STAGNANT UPPER LEVEL LOW PRESSURE AREA OVER THE NORTHEASTERN
STATES WILL MOVE TO THE EAST OVER THE NEXT TWO DAYS. WEAK HIGH
PRESSURE WILL MOVE IN FOR LATE MONDAY AND EARLY TUESDAY. LOW
PRESSURE WILL DEVELOP IN THE HIGH PLAINS SUNDAY AND MONDAY AND
TAKE A TRACK THROUGH THE OHIO VALLEY AND MID-ATLANTIC STATES
TUESDAY NIGHT AND WEDNESDAY. THIS STORM WILL PROBABLY PASS TO THE
SOUTH OF THE STATE...BUT IT COULD BRING SOME SNOW OR RAIN TO
SOUTHERN PENNSYLVANIA IN THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
VERY MINOR CHANGES MADE TO THE OVERNIGHT PERIOD. REFER TO THE LONG
TERM PERIOD FOR SOME UPWARD MODIFICATIONS TO POPS AND SNOW POTENTIAL
FOR THE MIDWEEK PERIOD.
A WELL-DEFINED PLUME OF DEEPER MOISTURE WAS ROTATING SWD /ALOGN WITH
MORE ILL-DEFINED SPOKES OF UPPER ENERGY AROUND THE BACK SIDE OF THE
VERY SLOW MOVING UPPER LOW /CENTERED NEAR KNYC LATE THIS EVENING/.
SNOW SHOWERS WILL BE FREQUENT ACROSS THE NRN AND WESTERN
MTNS...WHERE MANY LOCATIONS WILL SEE AN ADDITIONAL FRESH COATING TO
ONE INCH OF SNOW OVERNIGHT. THIS TREND IS IN LINE WITH
THE 20Z HRRR AND EARLIER 12/18Z 4 AND 12KM VERSIONS OF THE NAM.
SOME OF THE RIDGE TOPS /ESPECIALLY ACROSS THE LAURELS/ COULD SEE
UP TO 2 INCHES OF POWDERY SNOW.
MAINLY FLURRIES ARE EXPECTED ACROSS THE SCENT AND SERN
ZONES...WHILE A FEW SNOW SHOWERS WITH 2SM VSBYS COULD SPILL OFF
THE ALLEGHENIES AND MAKE IT TO THE CENTRAL MTNS AND MIDDLE SUSQ
VALLEY...GIVING A DUSTING IN SOME AREAS.
OVERNIGHT LOW TEMPS WILL VARY FROM THE MID TEENS ACROSS THE NW...TO
THE MID 20S IN THE SE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
MORE OF THE SAME EXPECTED FOR SUNDAY AS UPPER LOW DEPARTS ONLY
SLOWLY TO THE NORTHEAST. CLOUDS AND SLIGHTLY COOLER THAN NORMAL
MAXES WILL PREVAIL AGAIN ON SUNDAY. CONTINUING BREEZY NW WIND AND
SMALL CHANCES FOR SNOW SHOWERS AND FLURRIES...TAPERING TO NIL PAST
THE RIDGE AND VALLEY REGION.
HIGHS WILL BE WITHIN A DEGREE OR TWO OF SATURDAY AFTERNOON
READINGS RANGING FROM THE MID 20S NORTHWEST TO AROUND 40
SOUTHEAST. PERHAPS JUST A TOUCH COOLER IN THE NW WHERE 8H TEMPS GO
DOWN ONE OR TWO DEGS C.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
03Z SUNDAY UPDATE...
MODELS AND ENSEMBLES ARE COMING INTO BETTER AGREEMENT ON THE TRACK
OF THE MIDWEEK STORM HEADED OUR WAY FROM THE MID MISS VALLEY.
GRANTED...THERE/S STILL QUITE A BIT OF UNCERTAINTY...SINCE THE U.S.
MODELS...15Z AND 21Z SREF...ALONG WITH THE 06Z THROUGH 18Z GEFS HAVE
ALL TRENDED NORTH BY 50-100 NM WITH THE AXIS OF HEAVIEST QPF. THE
LATEST NAEFS AND EC ARE STILL ON THE SOUTHERN ENVELOPE OF SOLUTIONS
IN TRACKING THE SFC LOW NEAR OR JUST TO THE NORTH OF THE NC/WVA
LINE. THE NAEFS IS A TAD FURTHER NORTH...WHILE THE EC/S APPROX 530
DAM CLOSED LOW CENTER IS TAKEN ACROSS TENN AND NC. ALTHOUGH OUR
SOUTHERN COUNTIES ARE UNDER THE GUN FOR SOME POTENTIALLY HEAVY
SNOW...THE BIGGEST SIGNAL FOR AT LEAST SOME LIGHT SNOW ACROSS MUCH
OF CENTRAL /AND PERHAPS EVEN NCENT/ PENN IS THE BROAD AREA OF
ANOMALOUS EASTERLY LOW TO MID LEVEL FLOW BETWEEN THIS DEEP LOW...AND
THE OMEGA BLOCK ACROSS SERN CANADA.
THE MAIN THING TO EMPHASIZE AT THIS EARLY POINT IN TIME...IS THE
HIGH CONFIDENCE/POTENTIAL FOR A HIGH IMPACT STORM WITH HEAVY SNOW
SOMEWHERE ACROSS THE CENTRAL APPALACHIANS TO THE MID ATLANTIC
PIEDMONT...WITH OBVIOUSLY LESS CONFIDENCE IN THE STORM TRACK.
MODIFIED GRIDDED DATA TO INDICATE LIKELY POPS...WITH UP TO SEVERAL
INCHES OF STORM TOTAL SNOWFALL ACROSS THE SOUTHERN HALF OF PENN LATE
TUESDAY THROUGH WEDNESDAY.
PREVIOUS AFTERNOON DISCUSSION FOLLOWS...
PERSISTENT UPPER TROF OVER THE NORTHEASTERN UNITED STATES WILL GET
A QUICK REINFORCING SHOT OF COOLER AIR ON MONDAY BEFORE IT EXITS
TO THE NORTHEAST. LOWS SUN NIGHT WILL BE SLIGHTLY COOLER THAN THE
NIGHT BEFORE...WITH HIGHS MON JUST A FEW DEGREES HIGHER THAN SUNDAY.
TUESDAY A WEAK SFC RIDGE WILL BE IN PLACE OVER CENTRAL
PA...BRINGING QUIET WEATHER ALONG WITH WARMER TEMPERATURES.
VIGOROUS UPPER TROF WILL BE SLIDING ACROSS CENTRAL PLAINS
TUES...AND FCST TO DIVE SEWD TOWARD THE CAROLINAS...SPINNING UP A
SFC LOW OVER N CAROLINA/VIRGINA ON WED. HIGH LATITUDE BLOCKING AND
EASTWARD PROPAGATION OF SHORTWAVE ENERGY SHOULD KEEP CENTER OF
MAIN LOW TO OUR SOUTH...SLIPPING OFF THE COAST S OF DELMARVA.
SYSTEM WILL HAVE SOME PHASING ISSUES...WITH SECONDARY WEAKER SFC
LOW EDGING TOWARD W PA FROM OHIO VALLEY...BUT IMPACT TO EAST COAST
WILL BE CENTERED AROUND WED-WED NIGHT. MODELS STILL HAVE SOME
DIFFERENCES...BUT GENERALLY MORE IN LINE THAN PREVIOUS RUNS...WITH
A SOUTHERN TRACK BRINGING HEAVY SNOW TO THE VIRGINIA`S APPEARING
MOST LIKELY AT THIS TIME...WITH CONSENSUS AMONG 12Z MODELS TAKING
THE BULK OF QPF WELL SOUTH OF THE MASON DIXON LINE. AS
USUAL...EXPECT MODELS TO WAVER OVER THE NEXT SEVERAL DAYS...BUT
THE POTENTIAL EXISTS FOR SOME ACCUMULATING SNOW OR RAIN LATE
TUESDAY INTO WEDNESDAY NIGHT...BUT ALL OF THE MOST IMPORTANT
DETAILS REMAIN UNCLEAR AT THIS EARLY TIME.
BEHIND THIS SYSTEM FOR LATE WEEK INTO THE WEEKEND...MINIMAL COLD
AIR TO BE SEEN AS FLOW BECOMES WESTERLY. BY FRI...HIGHS SHOULD BE
IN THE 40S AREA-WIDE...AND SEVERAL DEGREES HIGHER ON SAT WITH A
PLEASANT SPRING DAY IN STORE.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
NW FLOW REGIME WILL REMAIN ENTRENCHED ACROSS CENTRAL PA FOR THE
NEXT 36 HOURS. ANY BREAKS IN THE CLOUDS WILL CLOSE UP THIS EVENING
AND CIGS WILL LOWER AGAIN...WITH MVFR-OCNL IFR CONDITIONS IN
PLACE ACROSS WESTERN HIGHER TERRAIN AS UPSLOPE FLOW KEEPS LOW
CLOUDS AND SCATTERED SNOW SHOWERS REMAIN LOCKED IN. CENTRAL
TERMINALS SUCH AS ALTOONA AND STATE COLLEGE WILL REMAIN IN THE
2-4KFT RANGE FOR CEILINGS. EXPECT THEM TO BE VFR MOST OF THE TIME
DURING THE REST OF THE EVE AND AGAIN SUN AFTN...BUT A FEW
FLURRIES AND 2KFT CIGS COULD DRIFT IN FM THE NW - ESP TONIGHT.
MDT/LNS WILL STAY VFR. WINDS WILL REMAIN GUSTY OUT OF THE
NORTHWEST.
OUTLOOK...
MON-TUE AM...SCATTERED SNOW SHOWERS WITH INTERMITTENT CIG/VSBY
REDUCTIONS N AND W. VFR SE.
TUE PM-WED...STORM WITH A TRACK THRU MID ATLC STATES WILL BRING
THE POSS OF LOWERED CIGS/VSBYS TO THE AREA - ESP THE SRN HALF OF
THE AREA.
WED PM-THU...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...LAMBERT
SHORT TERM...DANGELO
LONG TERM...LAMBERT/RXR
AVIATION...DANGELO/GARTNER
AREA FORECAST DISCUSSION
NWS SPOKANE WA
958 PM PST Sat Mar 2 2013
.SYNOPSIS...After the warm and mostly dry conditions today, a
strong storm system will bring the threat of rain, mountain snow,
and gusty winds tonight and Sunday. Monday should be seasonal and
dry, then a slow moving low pressure system will bring a return to
unsettled weather conditions Tuesday through Thursday.
&&
.DISCUSSION...
Some forecast changes have been made through Sunday. An upper
level trough passing through the region tonight will send a strong
cold front through the area. The main impact from this front will
be breezy to windy conditions overnight into Sunday as well as
light to moderate snow accumulations in the mountains.
The NAM and ECMWF model has the best handle on the current
situation with the GFS model ignored due to poor handling of
relative humidity through the atmospheric column this evening (wet
bias). A mid level front stretching from the Blues and Camas
Prairie to the Central Panhandle Mountains will exit the area this
evening with the surface cold front quickly following overnight.
Areas of light rain and high mountain snow will continue through
the evening in these areas with the mid level front over the area.
Meanwhile the surface cold front went through Wenatchee at 7 PM
and satellite and surface observations show a strong rain shadow
east of the Cascades with 850mb winds out of the west-southwest at
30 knots. With this being a fast moving front tonight and strong
downslope flow this rain shadow may extend into most of Eastern
Washington as well as the Lewiston area with the latest HRRR and
00z NAM keeping most of the precipitation north and east of the
Columbia Basin. Also the best instability aloft will be passing
north of these areas through British Columbia...northern
Washington...and the north Idaho Panhandle under the coldest pool
of 500mb temps of -33 to -35C. With a more substantial rain shadow
expected precipitation chances were lowered for most of Central
and Eastern Washington tonight. Behind the front a very
pronounced dry slot on water vapor imagery will be aimed directly
at central and southern Washington extending into the Camas
Prairie and Central Panhandle Mountains. This will greatly limit
the degree of snow showers Sunday morning in these areas and thus
precipitation chances and snow accumulations were lowered. Could
see a bit more snow shower activity over the North Idaho Panhandle
and northeast Washington Mountains Sunday morning under the cold
pool aloft.
With strong cold advection behind the cold front and 850mb winds
of 25-35 knots breezy to windy conditions will develop overnight
into Sunday and the wind forecast looks on track. With 850mb temps
falling to near -5C Sunday morning mountain low temperatures were
adjusted downward with other minor changes elsewhere. JW
&&
.AVIATION...
06Z TAFS: Winds will increase with gusts in the 20-35 mph range
overnight into Sunday afternoon along and behind a strong cold front
passage. Brief rain is possible with the front passage tonight at
KGEG/KSFF/KCOE/KPUW/KLWS. Behind the front significant drying will
lead to clearing skies at the TAF sites in the 08-15z time frame
from west to east. Then under the cold air associated with the
trough will see an increase in cumulus clouds as the atmosphere
destabilizes during the day on Sunday. Shower chances will increase
Sunday afternoon, especially in the Eastern Washington and North
Idaho Mountains. A few may still fall around the KGEG-KCOE-KPUW
region but the risk is slight. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 31 41 26 42 30 46 / 50 40 0 0 0 20
Coeur d`Alene 32 39 26 42 29 47 / 80 60 10 0 0 20
Pullman 32 41 29 44 30 50 / 70 40 0 0 0 10
Lewiston 40 48 32 50 34 56 / 50 20 10 0 0 10
Colville 31 43 26 49 28 50 / 50 30 0 0 0 40
Sandpoint 32 38 29 41 29 44 / 100 70 20 0 0 20
Kellogg 34 36 29 42 28 46 / 100 100 50 0 0 20
Moses Lake 36 54 26 47 31 49 / 10 0 0 0 0 40
Wenatchee 35 52 29 46 32 48 / 10 0 0 0 10 40
Omak 33 47 22 43 26 45 / 20 0 0 0 10 40
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
817 PM PST Sat Mar 2 2013
.SYNOPSIS...After the warm and mostly dry conditions today, a
strong storm system will bring the threat of rain, mountain snow,
and gusty winds tonight and Sunday. Monday should be seasonal and
dry, then a slow moving low pressure system will bring a return to
unsettled weather conditions Tuesday through Thursday.
&&
.DISCUSSION...
Some forecast changes have been made through Sunday. An upper
level trough passing through the region tonight will send a strong
cold front through the area. The main impact from this front will
be breezy to windy conditions overnight into Sunday as well as
light to moderate snow accumulations in the mountains.
The NAM and ECMWF model has the best handle on the current
situation with the GFS model ignored due to poor handling of
relative humidity through the atmospheric column this evening (wet
bias). A mid level front stretching from the Blues and Camas
Prairie to the Central Panhandle Mountains will exit the area this
evening with the surface cold front quickly following overnight.
Areas of light rain and high mountain snow will continue through
the evening in these areas with the mid level front over the area.
Meanwhile the surface cold front went through Wenatchee at 7 PM
and satellite and surface observations show a strong rain shadow
east of the Cascades with 850mb winds out of the west-southwest at
30 knots. With this being a fast moving front tonight and strong
downslope flow this rain shadow may extend into most of Eastern
Washington as well as the Lewiston area with the latest HRRR and
00z NAM keeping most of the precipitation north and east of the
Columbia Basin. Also the best instability aloft will be passing
north of these areas through British Columbia...northern
Washington...and the north Idaho Panhandle under the coldest pool
of 500mb temps of -33 to -35C. With a more substantial rain shadow
expected precipitation chances were lowered for most of Central
and Eastern Washington tonight. Behind the front a very
pronounced dry slot on water vapor imagery will be aimed directly
at central and southern Washington extending into the Camas
Prairie and Central Panhandle Mountains. This will greatly limit
the degree of snow showers Sunday morning in these areas and thus
precipitation chances and snow accumulations were lowered. Could
see a bit more snow shower activity over the North Idaho Panhandle
and northeast Washington Mountains Sunday morning under the cold
pool aloft.
With strong cold advection behind the cold front and 850mb winds
of 25-35 knots breezy to windy conditions will develop overnight
into Sunday and the wind forecast looks on track. With 850mb temps
falling to near -5C Sunday morning mountain low temperatures were
adjusted downward with other minor changes elsewhere. JW
&&
.AVIATION...
00Z TAFS: Cold front passes with increasing precip this evening,
before chances start to wind down from the west late tonight into
Sunday morning. Expect mainly rain around TAF sites, though some
snow may mix in overnight into Sunday morning closer to the ID
panhandle. Predominantly VFR at TAF sites; brief MVFR cigs
possible within steadier precipitation. Breezy conditions late
tonight with the frontal and vort max passage, then again Sunday
afternoon in the unstable, mixed atmosphere. Shower chances linger
in the instability Sunday afternoon, especially near the mountains.
A few may still fall around the KGEG-KCOE-KPUW region but the
risk is slight. /J. Cote`
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 31 41 26 42 30 46 / 50 40 0 0 0 20
Coeur d`Alene 32 39 26 42 29 47 / 80 60 10 0 0 20
Pullman 32 41 29 44 30 50 / 70 40 0 0 0 10
Lewiston 40 48 32 50 34 56 / 50 20 10 0 0 10
Colville 31 43 26 49 28 50 / 50 30 0 0 0 40
Sandpoint 32 38 29 41 29 44 / 100 70 20 0 0 20
Kellogg 34 36 29 42 28 46 / 100 100 50 0 0 20
Moses Lake 36 54 26 47 31 49 / 10 0 0 0 0 40
Wenatchee 35 52 29 46 32 48 / 10 0 0 0 10 40
Omak 33 47 22 43 26 45 / 20 0 0 0 10 40
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
325 AM CST SUN MAR 3 2013
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
325 AM CST SUN MAR 3 2013
MAIN FOCUS IS ON THE LONG PERIOD OF ACCUMULATING SNOW LATE TONIGHT
THROUGH TUESDAY
CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT
ANALYSIS SHOWED A POTENT SHORTWAVE TROUGH OVER SOUTHERN BRITISH
COLUMBIA INTO WASHINGTON STATE...RIDGING FROM BAJA CALIFORNIA INTO
SOUTHERN SASKATCHEWAN...AND A SHORTWAVE TROUGH DROPPING INTO EASTERN
WISCONSIN. PLENTIFUL UPPER LEVEL MOISTURE WAS STREAMING NORTH OUT OF
THE TROPICAL EAST PACIFIC AND THROUGH THE TOP OF THE UPPER RIDGE...
MANIFESTING ITSELF AS CIRRUS CLOUD COVER OVER THE DAKOTAS INTO
WESTERN MINNESOTA. EAST OF THIS CIRRUS...AN ALTOSTRATUS DECK WAS
PRESENT ACROSS MUCH OF MINNESOTA AND IOWA. THIS DECK IS A RESULT OF
RELATIVELY HIGHER MOISTURE OVER THE DAKOTAS GETTING ISENTROPICALLY
LIFTED. 00Z SOUNDING DATA SHOWED PRECIPITABLE WATER OF 0.16 INCHES
AT MPX...OR 66 PERCENT OF NORMAL...COMPARED TO 0.4 INCHES AT BIS AND
ABR OR 175 PERCENT OF NORMAL. BIG 850MB TEMPERATURE DIFFERENCE
TOO...WITH MPX AT -8C COMPARED TO AROUND 3C AT BIS AND ABR. DESPITE
THE PRESENCE OF THE ALTOSTRATUS DECK AND SOME LIGHT RETURNS ON
REGIONAL RADAR...NOTHING HAS REACHED THE SURFACE DUE TO DRIER LOW
LEVEL AIR SEEN ON THAT 00Z MPX SOUNDING. DRY AIR SEEN ON THE 00Z GRB
SOUNDING HAS ALSO PREVENTED MUCH FOR CLOUDS WITH THE SHORTWAVE
DROPPING THROUGH EASTERN WISCONSIN. AT THE SURFACE...A RIDGE OF HIGH
PRESSURE ENCOMPASSED MUCH OF THE WESTERN GREAT LAKES WHILE LOW
PRESSURE WAS DEEPENING IN SOUTHERN ALBERTA. LASTLY...REGARDING THAT
POTENT SHORTWAVE TROUGH...00Z RAOB DATA SHOWED SOME PRETTY
IMPRESSIVE 500MB HEIGHT FALLS...AROUND 100 METERS IN 12 HOURS.
ALL MODELS CONTINUE TO INDICATE THAT THE LONG PERIOD OF SNOW WILL
OCCUR FROM THE NORTHERN PLAINS SOUTHEAST INTO PORTIONS OF THE
FORECAST AREA. THREE DISTINCT FORCING MECHANISMS ARE GOING TO GOVERN
THIS SNOW...WITH THE LAST TWO ITEMS MODULATING THE INTENSITY AND
PLACEMENT...
1. A LOW TO MID LEVEL FRONTOGENESIS ZONE...WHICH CAN ALREADY BE SEEN
IN THE 00Z SOUNDING DATA NOTED BY THE SHARP DIFFERENCE IN 850MB
TEMPS BETWEEN MPX AND ABR.
2. A HARD TO SEE SHORTWAVE ON WATER VAPOR CURRENTLY IN SOUTHERN
IDAHO PROGGED TO MOVE WEST TO EAST THROUGH THE FORECAST AREA ON
MONDAY
3. THE POTENT UPPER TROUGH WHICH DROPS SOUTHEAST OUT OF THE NORTHERN
PLAINS ON MONDAY AND INTO THE MID-MISSISSIPPI VALLEY BY LATE TUESDAY
OVERALL...MODELS AGREE REALLY WELL TONIGHT INTO MONDAY IN THE
HANDLING OF THE FRONTOGENESIS ZONE AND SHORTWAVE MOVING THROUGH.
BETWEEN 00-06Z TONIGHT...SOUTH WINDS REALLY PICK UP ON THE 285-290K
SURFACES IN SOUTHWEST MINNESOTA AHEAD OF THE APPROACHING
SHORTWAVE...HELPING TO INCREASE THE INTENSITY OF THE FRONTOGENESIS
ZONE. COMBINED WITH PACIFIC MOISTURE ALREADY PRESENT IN THE
DAKOTAS...SNOW SHOULD EASILY BREAK OUT. AS THE SHORTWAVE PRESSES
EAST TOWARDS THE AREA AFTER 06Z...THE FRONTOGENESIS ZONE SHIFTS EAST
WITH IT...IMPACTING LOCATIONS WEST OF THE MISSISSIPPI RIVER. HIGHER
HORIZONTAL RESOLUTION QPF DATA FROM THE 03.00Z NAM...HIRES-ARW/NMM
AND REGIONAL CANADIAN SUGGEST ANYWHERE FROM 0.25-0.30...HIGHEST IN
THE AUSTIN/CHARLES CITY AREA. EVEN HIGHER AMOUNTS LOOK POSSIBLE TO
THE NORTHWEST. SOUNDINGS DEPICT ONLY A 75MB LAYER OF DENDRITIC
GROWTH...WAY UP AROUND 600MB...WITH LIFT THROUGHOUT A LOT OF THE
COLUMN. THUS...THINKING SNOW TO WATER RATIOS SHOULD STAY AROUND 10
TO 1...YIELDING UPWARDS OF 2-3 INCHES BY 12Z. THE FRONTOGENESIS ZONE
CONTINUES TO PUSH EAST DURING THE DAY MONDAY BY THE SHORTWAVE...
EVENTUALLY STALLING OUT OVER THE SOUTHWEST 2/3 OF THE FORECAST AREA
FOR THE AFTERNOON. THE HEAVIEST PRECIPITATION LOOKS TO OCCUR IN THE
MORNING WITH ENHANCEMENT FROM THE SHORTWAVE BEFORE THE SHORTWAVE
LIFTS OFF. COULD SEE UPWARDS OF 0.25 INCH DURING THE MORNING IN
SOUTHEAST MN INTO PORTIONS OF NORTHEAST IOWA...EQUATING TO ANOTHER
2-3 INCHES OF SNOW. THUS...FOR THE 06-18Z MONDAY PERIOD...TOTALS OF
4-5 INCHES SEEM EASILY POSSIBLE ALONG/WEST OF A LINE FROM ROCHESTER
MN TO OELWEIN IA. FARTHER EAST...WITH PRECIPITATION TAKING LONGER TO
SPREAD IN...MUCH LIGHTER AMOUNTS ARE ANTICIPATED...ESPECIALLY IN THE
DRIER AIR NORTHEAST OF I-94.
MONDAY NIGHT AND TUESDAY IS A LITTLE MORE PROBLEMATIC BECAUSE MODELS
HAVE STRUGGLED WITH THE POTENT UPPER TROUGH. EVEN TODAY...THERE ARE
QUESTIONS ON HOW MUCH EASTERLY MOVEMENT THE CORE OF THE UPPER TROUGH
WILL HAVE AS IT COMES OUT OF THE DAKOTAS. THE 03.00Z/06Z NAM REMAIN
THE FARTHEST EAST...TRACKING ACROSS CENTRAL/EASTERN IOWA TUESDAY
MORNING. ON THE OTHER END OF THE SPECTRUM IS THE 03.00Z UKMET...
DROPPING INTO NORTHEAST KANSAS AT THE SAME TIME. THE 03.00Z
GFS/CANADIAN/ECMWF ARE IN THE MIDDLE...TRACKING ACROSS FAR WESTERN
IOWA INTO NORTHWEST MISSOURI. OVERALL...THERE HAS BEEN A SHIFT EAST
WITH THE TRACK OVER THE PAST FEW MODEL RUNS...PUTTING MORE OF THE
FORECAST AREA INTO PRECIPITATION. AS SUCH...HAVE INCREASED AND
EXPANDED PRECIPITATION CHANCES FARTHER EAST. THE SETUP FOR MONDAY
NIGHT AND TUESDAY LOOKS MORE IMPRESSIVE DUE TO STRONGER DPVA FORCING
THE UPPER TROUGH. A NICE TROWAL SHOULD DEVELOP AS WELL ON THE
NORTHEAST SIDE OF THE UPPER TROUGH. ON TOP OF THIS...THE UPPER LOW
BRINGS IN COLDER AIR...POTENTIALLY RESULTING IN A DEEPER DENDRITIC
GROWTH ZONE. IN ANY EVENT...THE COLDER WILL CAUSE SNOW RATIOS TO
INCREASE. FOR BOTH QPF AND SNOW RATIOS...TOOK A MODEL CONSENSUS...
WHICH YIELDS ABOUT 6 TO 8 INCHES OF SNOWFALL SOUTHWEST OF I-94 OVER
THE MONDAY NIGHT AND TUESDAY PERIOD. THESE COULD EASILY BE HIGHER...
AS WELL AS EITHER SHIFTED EAST OR WEST DEPENDING ON THE EXACT UPPER
LOW TRACK.
REGARDING HAZARDS...WITH THE SHIFT EAST IN THE MONDAY NIGHT/TUESDAY
PERIOD...AN EXPANSION OF THE WATCH IS REQUIRED TO INCLUDE FROM
BUFFALO COUNTY SOUTHEAST TO GRANT COUNTY WI. CONVERTING THE EXISTING
WATCH TO WARNING OR ADVISORY ELSEWHERE IS VERY DIFFICULT AT THIS
TIME. ALTHOUGH MODELS AGREE WELL ON THE TONIGHT/MONDAY PERIOD...AT
MOST IT APPEARS A 12 HOUR PERIOD OF 3-5 INCHES WITH A 24 HOUR TOTAL
OF UP TO 6 INCHES...ALL BELOW WARNING CRITERIA. IMPACT WISE...THE
MORNING COMMUTE ACROSS SOUTHEAST MN AND NORTHEAST IOWA
DEFINITELY WILL BE AFFECTED...BUT THE SNOWFALL RATE RIGHT NOW DOES
NOT LOOK HIGH ENOUGH TO JUSTIFY A WARNING. OVER THE COURSE OF THE
ENTIRE PERIOD THROUGH TUESDAY...LOCATIONS ACROSS SOUTHEAST MINNESOTA
INTO NORTHEAST IOWA COULD PICK UP UPWARDS OF 10-15 INCHES...BUT THIS
IS OVER A 42 HOUR TIMEFRAME...WHICH MEANS SOME MELTING/SETTLING WILL
OCCUR. IN ADDITION...THE MONDAY NIGHT/TUESDAY PERIOD HAS GOT A LOT
OF UNCERTAINTY WITH THE UPPER TROUGH TRACK. THUS...AFTER
COLLABORATION WITH MPX...DMX AND DVN...HAVE LEFT THE WATCH INTACT
FOR NOW. CONVERSIONS TO WARNINGS AND/OR ADVISORIES WILL LIKELY TAKE
PLACE DURING THE DAY.
PRECIPITATION LOOKS TO TAIL OFF PRETTY QUICK TUESDAY NIGHT AS THE
UPPER TROUGH HEADS OFF TO THE MID-ATLANTIC REGION. DID PUT A 20
PERCENT CHANCE IN FOR THE EVENING ACROSS MUCH OF THE AREA WITH
SUGGESTIONS THE COLD CONVEYOR BELT MAY STILL BE AFFECTING US.
.LONG TERM...WEDNESDAY THROUGH SATURDAY NIGHT
325 AM CST SUN MAR 3 2013
AFTER AN ACTIVE SHORT TERM PERIOD...THE LONG TERM LOOKS MAINLY QUIET
WITH A PATTERN SHIFT STILL PROGGED TO OCCUR. A DEEP TROUGH IS
PROGGED TO MOVE INTO THE WESTERN U.S. WEDNESDAY INTO THURSDAY...
CAUSING RIDGING TO SHIFT EAST AND BUILD DOWNSTREAM TOWARDS THE
FORECAST AREA. SUBSIDENCE UNDER THE UPPER RIDGE COMBINED WITH HIGH
PRESSURE COMING THROUGH AT THE SURFACE WILL YIELD DRY AND LIKELY
MOSTLY SUNNY DAYS. 850MB TEMPS WARM AS WELL...ALLOWING HIGHS TO
CLIMB BACK TO NORMAL LEVELS BY THURSDAY.
FOR THURSDAY NIGHT AND HEADING INTO THE WEEKEND...THE WESTERN TROUGH
LOOKS TO SPLIT INTO TWO...WITH THE BULK OF IT CLOSING OFF INTO AN
UPPER LOW IN THE DESERT SOUTHWEST. THE NORTHERN STREAM PORTION OF
THIS TROUGH IS FORECAST TO HEAD UP INTO NORTHERN ONTARIO ON
FRIDAY...BRINGING A WEAKENING COLD FRONT THROUGH THE AREA. FOLLOWED
THE CONSENSUS WHICH HAD A 20 PERCENT CHANCE UP IN NORTHERN WISCONSIN
FOR FRIDAY. 20 PERCENT CHANCES ARE ALSO IN THE FORECAST FOR FRIDAY
NIGHT EVERYWHERE...ASSOCIATED WITH POSSIBLE WEAK FRONTOGENESIS IN
THE WAKE OF THE FRONTAL PASSAGE. DRIER WEATHER FOLLOWS FOR
SATURDAY...THOUGH THE LATEST 03.00Z ECMWF TRIES TO MAINTAIN THE
FRONTOGENESIS AND LIGHT PRECIPITATION. THUS...LATER FORECASTS MAY
NEED TO ADD SOME CHANCES IN FOR SATURDAY. TEMPERATURES BOTH FRIDAY
AND SATURDAY SHOULD END UP AT OR ABOVE NORMAL...EVEN WITH THE
PASSAGE OF THE WEAK COLD FRONT SINCE PACIFIC AIR IS FLOWING IN
BEHIND IT.
&&
.AVIATION...
1100 PM CST SAT MAR 2 2013
MID LEVEL CLOUDS WILL SHIFT WEST TO EAST ACROSS THE REGION
TONIGHT...MOSTLY 6-8 KFT...ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE.
NO -SN IS EXPECTED. LIGHT WIND FIELD AS A SFC HIGH MOVES ACROSS THE
UPPER MISSISSIPPI RIVER VALLEY. SOME BR FORMED IN THIS RIDGE LAST
NIGHT...BUT THE CLOUDS AND SIZABLE T/TD SHOULD KEEP THOSE CHANCES AT
BAY. WINDS WILL BECOME SOUTHEASTERLY ON SUNDAY AS THE HIGH MOVES
TOWARD THE EASTERN GREAT LAKES. OVERALL...VFR CONDITIONS ARE
EXPECTED TONIGHT/SUNDAY.
A WINTER STORM WILL IMPACT THE REGION STARTING LATE SUNDAY
NIGHT...PERSISTING INTO TUE. A PROLONGED PERIOD OF VSBY RESTRICTING
-SN IS LOOKING PROBABLE...WITH THE POSSIBILITY OF SIGNIFICANT
ACCUMULATIONS - ESPECIALLY KRST. MVFR CIGS WILL PROBABLY HOLD OFF
UNTIL AFTER 12Z MON. ITS A STORM TO BE WATCHED AS IT WILL IMPACT
AVIATION INTERESTS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
325 AM CST SUN MAR 3 2013
WI...WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR WIZ032-033-041-053>055-061.
MN...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR MNZ079-086-087-094-095.
WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR MNZ088-096.
IA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR IAZ008-009-018-019.
WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR IAZ010-011-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
719 AM EST SUN MAR 3 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT AND REMAIN
THROUGH EARLY THIS WEEK. LOW PRESSURE AND ITS TRAILING COLD FRONT
WILL IMPACT THE AREA TUESDAY NIGHT INTO EARLY WEDNESDAY...FOLLOWED
AGAIN BY HIGH PRESSURE THROUGH LATE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE REGION WILL REMAIN UNDER THE INFLUENCE OF A DEEP LONGWAVE
TROUGH TODAY. THE TROUGH IS FORECAST TO GRADUALLY PUSH OFFSHORE AS
THE DAY PROGRESSES ALLOWING MID-LEVEL HEIGHTS TO STEADILY RISE IN
ITS WAKE. ALTHOUGH THE MID-LEVEL THERMAL ADVECTION PATTERN WILL
BECOME NEUTRAL TO SLIGHTLY POSITIVE LATER TODAY...H8 TEMPERATURES
OF -6 TO -7C WILL STILL KEEP HIGH TEMPERATURES ABOUT 10-15 DEGREES
BELOW NORMAL FOR EARLY MARCH. LOW-LEVEL THICKNESSES SCHEMES
SUPPORT HIGHS IN THE LOWER 50S WHICH LOOK REASONABLE PER MODEL
BUFR SOUNDINGS.
STEEP MID-LEVEL LAPSE RATES NEARING 6 C/KM COUPLED WITH SOME
LINGERING MID-LEVEL MOISTURE WILL LIKELY SUPPORT THE FORMATION OF
SOME SORT OF SHALLOW CUMULUS FIELD ONCE THE NOCTURNAL INVERSION
BURNS OFF. HOWEVER...IT IS UNCLEAR HOW EXTENSIVE THIS CLOUD DECK
WILL BECOME. BUFKIT CLOUD TOOLS SUGGEST A RATHER THICK 6 KFT CLOUD
LAYER WILL FORM...WHILE OTHER DATA SUCH AS THE WRF AND GEM
SIMULATED SATELLITE PRODUCTS SUPPORT CONSIDERABLY LESS CLOUD
COVER. CONSIDERING THE H9-H7 FLOW DOES NOT BECOME TRULY DOWNSLOPE
DOMINATED UNTIL MID-LATE AFTERNOON...SUSPECT THERE WILL BE ENOUGH
CLOUDS TO SUPPORT A PARTLY CLOUDY SKY CHARACTER...HOWEVER SKIES
RANGING ANYWHERE FROM CLOUDY TO COMPLETELY SUNNY ARE DISTINCT
POSSIBILITIES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
TONIGHT...SURFACE HIGH PRESSURE WILL BUILD IN FROM THE WEST
TONIGHT AS WEAK UPPER RIDGING OVER THE SOUTHERN PLAINS NUDGES
EAST. THERE LOOKS TO BE ENOUGH OF A RESIDUAL PRESSURE GRADIENT
ALONG THE EASTERN FLANKS OF THE SURFACE HIGH TO PREVENT FULL
BOUNDARY LAYER DECOUPLING AFTER SUNSET...EXCEPT OVER INTERIOR
SOUTHEAST GEORGIA WHERE DECOUPLING APPEARS MORE LIKELY. LOWS WILL
RANGE FROM THE UPPER 20S INLAND TO THE MID 30S AT THE BEACHES WITH
A FEW MID 20S LIKELY IN SOME SHELTERED AREAS OF FAR INTERIOR
SOUTHEAST GEORGIA.
MONDAY...SURFACE HIGH PRESSURE AND SHORTWAVE RIDGING ALOFT WILL
QUICKLY FOLLOW IN THE WAKE OF THE DEPARTING UPPER TROUGH EARLY IN
THE DAY. MODEL FORECAST SOUNDINGS INDICATE DEEP LAYER DRY AIR DURING
THE DAYTIME HOURS WITHIN A PREDOMINANT WEST/NORTHWEST FLOW. HIGH
LEVEL CLOUDS COULD THEN SHIFT INTO THE AREA OVERNIGHT DOWNSTREAM OF
A DEVELOPING LOW IN THE LOWER MISSISSIPPI/TENNESSEE VALLEYS. RISING
HEIGHTS ALOFT AND MOSTLY CLEAR TO PARTLY CLOUDY SKIES WILL SUPPORT
MODERATING TEMPERATURES...WITH HIGHS REACHING THE UPPER 50S TO LOWER
60S AWAY FROM THE LOCALLY COOLER COASTLINE. LOW LEVEL FLOW WILL BACK
TO THE SOUTHWEST OVERNIGHT...AND WITH EVIDENCE OF SOME HIGHER LEVEL
CLOUDS PROVIDING INSULATING EFFECTS AFTER MIDNIGHT...EXPECT LOW
TEMPERATURES TO BE NEARLY 10 DEGREES WARMER THAN THE PREVIOUS NIGHT.
LOWS WILL THUS RANGE FROM THE UPPER 30S INLAND TO THE LOWER 40S NEAR
THE BEACHES.
TUESDAY...A POTENT SHORTWAVE TROUGH WILL DESCEND FROM THE NORTHERN
PLAINS STATES INTO THE MID MISSISSIPPI VALLEY THROUGH THE AFTERNOON
HOURS...PROVIDING SIGNIFICANT ENERGY TO ORGANIZE AND INTENSIFY A
SURFACE LOW SYSTEM OVER THE TENNESSEE VALLEY BY SUNSET. THE UPPER
TROUGH WILL DEVELOP INTO A CUT OFF LOW OVERNIGHT...AT THE SAME TIME
THAT THE SURFACE SYSTEM BECOMES MORE COMPLEX AND TRACKS DUE
EASTWARD THROUGH THE CAROLINAS AND MID ATLANTIC STATES BY DAYBREAK
WEDNESDAY. THE FORECAST AREA WILL BE LOCATED WITHIN THE WARM
SECTOR OF THE SYSTEM DURING THE DAYTIME HOURS TUESDAY...WITH
SOUTHERLY FLOW SUPPORTING TEMPERATURES RISING INTO THE UPPER 60S
NORTHWEST ZONES TO THE LOWER 70S SOUTH OF THE SAVANNAH RIVER. WITH
THE FORECAST AREA INITIALLY LOCATED SOUTH OF THE WARM FRONT AND
WEST OF THE APPROACHING COLD FRONT...EXPECT RAIN TO BE SLOW TO
PUSH INTO THE REGION THROUGH THE AFTERNOON HOURS. RAIN CHANCES
WILL THEN INCREASE SIGNIFICANTLY AFTER SUNSET ONCE THE FRONT AND
UPPER LOW PASS OVER THE SOUTHEAST AND MID ATLANTIC STATES. GIVEN
DECENT MODEL AGREEMENT IN POTENTIAL AND COVERAGE OF RAIN...HAVE
INCREASED POPS INTO THE LIKELY RANGE FOR MUCH OF THE FORECAST AREA
FROM AROUND MIDNIGHT TO DAYBREAK WEDNESDAY MORNING. THICK
INSULATING CLOUD COVER...ALONG WITH SOUTHERLY FLOW VEERING TO THE
WEST...WILL KEEP LOW TEMPERATURES TUESDAY NIGHT RATHER MILD IN THE
UPPER 40S TO LOWER 50S.
WEDNESDAY...THE STACKED AND INTENSIFYING LOW SYSTEM WILL LIFT
EAST/NORTHEAST DURING THE MORNING HOURS...WHILE THE TRAILING COLD
FRONT RAPIDLY MOVES OFFSHORE. RAIN CHANCES WILL BE DECREASING FROM
WEST TO EAST INTO THE EARLY AFTERNOON...AND WITH THE SURFACE LOW
DISPLACED NORTH OF THE FORECAST AREA BY DAYBREAK...WRAP AROUND
MOISTURE DOES NOT APPEAR TO BE A CONCERN AT THIS TIME. HIGH
TEMPERATURES WILL BE COOLER IN THE UPPER 50S TO LOWER 60S BEHIND
THE DEPARTING COLD FRONT...HOWEVER MODERATE TO STRONG
OFFSHORE/DOWNSLOPE FLOW AND LINGERING CLOUD COVER WILL MITIGATE
MORE SIGNIFICANT COOLING POTENTIAL. A GREATLY TIGHTENED PRESSURE
GRADIENT ON THE BACKSIDE OF THE SURFACE LOW...AS WELL AS COLD
ADVECTION ENHANCING MIXING INTO A 30 TO 40 KT LOW LEVEL
JET...SUGGESTS BREEZY TO GUSTY WEST WINDS DURING THE AFTERNOON
HOURS.
LAKE WINDS...WINDS WILL APPROACH ADVISORY CRITERIA TUESDAY
AFTERNOON AS A 40 KT LOW LEVEL JET PASSES OVER THE REGION.
HOWEVER...MIXING WILL BE LIMITED WITHIN A WARM ADVECTION REGIME
OVER THE COOLER LAKE WATERS. A BETTER CHANCE FOR LAKE WIND
ADVISORY THRESHOLDS TO BE MET IS ON WEDNESDAY...AS A SIGNIFICANTLY
TIGHTENED PRESSURE GRADIENT AND STRONG COLD ADVECTION ENHANCES
MIXING AND SUPPORTS 20 TO 25 KT WINDS OVER THE LAKE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS THE POTENT LOW SYSTEM RAPIDLY TRACKS INTO THE ATLANTIC THROUGH
THE LATE WEEK PERIOD...SURFACE HIGH PRESSURE AND UPPER LEVEL
RIDGING WILL FOLLOW IN ITS WAKE. EXPECT DRY CONDITIONS TO THUS
PREVAIL THURSDAY THROUGH THE WEEKEND. RISING HEIGHTS ALOFT WILL
SUPPORT A GRADUAL WARMING TREND THROUGH THE PERIOD...WITH
TEMPERATURES PEAKING IN THE LOW TO MID 60S THURSDAY AND
FRIDAY...THEN POSSIBLY THE LOW 70S SATURDAY AND SUNDAY. LOW
TEMPERATURES WILL ALSO MODERATE INTO THE UPPER 30S TO LOWER 40S BY
LATE PERIOD.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
VFR.
EXTENDED AVIATION OUTLOOK...LOW TO MODERATE CHANCE OF REDUCED
CEILINGS/VISIBILITIES AT TIMES LATE TUESDAY INTO WEDNESDAY. WINDY
CONDITIONS WILL ALSO IMPACT THE TERMINALS TUESDAY AFTERNOON
THROUGH THURSDAY.
&&
.MARINE...
THIS MORNING...WINDS REMAIN QUITE RISKY AT BUOY 41008 WHICH IS A
BIT HIGHER THAN THE LATEST RAP RUN. WILL EXTEND THE SMALL CRAFT
ADVISORY FOR BOTH GEORGIA LEGS UNTIL 11 AM.
TODAY...WINDS WILL SLOWLY SUBSIDE ACROSS THE MARINE AREA TODAY AS
COLD AIR ADVECTION STEADILY WANES. ONCE THE MORNING SURGE
CEASES...EXPECT WINDS TO SETTLE INTO THE 10-15 KT RANGE...EXCEPT
15-20 KT OVER THE GEORGIA OFFSHORE WATERS. SEAS WILL RANGE FROM
2-3 FT NEARSHORE WATERS AND 3-4 FT OFFSHORE WATERS
TONIGHT...ANOTHER SURGE LOOKS LIKELY OVER THE WATERS TONIGHT AS
THE PRESSURE GRADIENT TIGHTENS A BIT AHEAD OF HIGH PRESSURE
NUDGING IN FROM THE WEST. SHOULD SEE AT LEAST FREQUENT GUSTS TO 25
KT OCCUR OVER THE WARMER WATERS ACROSS THE EASTERN PORTIONS FOR
THE GEORGIA OFFSHORE LEG...SO A SMALL CRAFT ADVISORY WILL LIKELY
BE NEEDED THERE. IT LOOKS A BIT MORE MARGINAL OVER THE NEARSHORE
WATERS SO WILL NOT HOIST AN ADVISORY JUST YET. SEAS WILL RANGE
FROM 2-4 FT NEARSHORE WATERS...4-6 FT OFFSHORE WATERS.
MONDAY...COLD ADVECTION WILL DIMINISH BY MID MORNING...AND ANY
SMALL CRAFT ADVISORIES SHOULD BE ALLOWED TO EXPIRE AT THAT TIME.
SOUTHERLY FLOW WILL THEN REMAIN BELOW ADVISORY THRESHOLDS FOR THE
REMAINDER OF THE DAY...AS HIGH PRESSURE BUILDS IN FROM FLORIDA AND
SETTLES OVER THE MARINE ZONES.
TUESDAY THROUGH THURSDAY...CONDITIONS WILL DETERIORATE AGAIN BY
LATER TUESDAY...AS ATLANTIC HIGH PRESSURE SHIFTS FARTHER AWAY FROM
THE MARINE ZONES AHEAD OF AN INTENSIFYING LOW PRESSURE SYSTEM
MOVING INTO THE TENNESSEE VALLEY. THE POTENT LOW SYSTEM WILL
INTENSIFY AS IT SHIFTS INTO THE CAROLINAS LATE TUESDAY/EARLY
WEDNESDAY AND THEN OFF THE MID ATLANTIC COAST WEDNESDAY
NIGHT/THURSDAY. A TRAILING COLD FRONT WILL SWEEP THROUGH THE
MARINE ZONES LATE TUESDAY NIGHT INTO EARLY WEDNESDAY. SMALL CRAFT
ADVISORY CRITERIA WILL BE REACHED BOTH AHEAD OF THE FRONT AND IN
ITS WAKE DURING THE MID WEEK PERIOD...WHILE THERE IS ALSO A GOOD
POTENTIAL FOR GALE CONDITIONS TO BE REACHED. WILL CONTINUE TO
MENTION THIS POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR AMZ354-
374.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
615 AM EST SUN MAR 3 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT AND REMAIN
THROUGH EARLY THIS WEEK. LOW PRESSURE AND ITS TRAILING COLD FRONT
WILL IMPACT THE AREA TUESDAY NIGHT INTO EARLY WEDNESDAY...FOLLOWED
AGAIN BY HIGH PRESSURE THROUGH LATE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE REGION WILL REMAIN UNDER THE INFLUENCE OF A DEEP LONGWAVE
TROUGH TODAY. THE TROUGH IS FORECAST TO GRADUALLY PUSH OFFSHORE AS
THE DAY PROGRESSES ALLOWING MID-LEVEL HEIGHTS TO STEADILY RISE IN
ITS WAKE. ALTHOUGH THE MID-LEVEL THERMAL ADVECTION PATTERN WILL
BECOME NEUTRAL TO SLIGHTLY POSITIVE LATER TODAY...H8 TEMPERATURES
OF -6 TO -7C WILL STILL KEEP HIGH TEMPERATURES ABOUT 10-15 DEGREES
BELOW NORMAL FOR EARLY MARCH. LOW-LEVEL THICKNESSES SCHEMES
SUPPORT HIGHS IN THE LOWER 50S WHICH LOOK REASONABLE PER MODEL
BUFR SOUNDINGS.
STEEP MID-LEVEL LAPSE RATES NEARING 6 C/KM COUPLED WITH SOME
LINGERING MID-LEVEL MOISTURE WILL LIKELY SUPPORT THE FORMATION OF
SOME SORT OF SHALLOW CUMULUS FIELD ONCE THE NOCTURNAL INVERSION
BURNS OFF. HOWEVER...IT IS UNCLEAR HOW EXTENSIVE THIS CLOUD DECK
WILL BECOME. BUFKIT CLOUD TOOLS SUGGEST A RATHER THICK 6 KFT CLOUD
LAYER WILL FORM...WHILE OTHER DATA SUCH AS THE WRF AND GEM
SIMULATED SATELLITE PRODUCTS SUPPORT CONSIDERABLY LESS CLOUD
COVER. CONSIDERING THE H9-H7 FLOW DOES NOT BECOME TRULY DOWNSLOPE
DOMINATED UNTIL MID-LATE AFTERNOON...SUSPECT THERE WILL BE ENOUGH
CLOUDS TO SUPPORT A PARTLY CLOUDY SKY CHARACTER...HOWEVER SKIES
RANGING ANYWHERE FROM CLOUDY TO COMPLETELY SUNNY ARE DISTINCT
POSSIBILITIES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
TONIGHT...SURFACE HIGH PRESSURE WILL BUILD IN FROM THE WEST
TONIGHT AS WEAK UPPER RIDGING OVER THE SOUTHERN PLAINS NUDGES
EAST. THERE LOOKS TO BE ENOUGH OF A RESIDUAL PRESSURE GRADIENT
ALONG THE EASTERN FLANKS OF THE SURFACE HIGH TO PREVENT FULL
BOUNDARY LAYER DECOUPLING AFTER SUNSET...EXCEPT OVER INTERIOR
SOUTHEAST GEORGIA WHERE DECOUPLING APPEARS MORE LIKELY. LOWS WILL
RANGE FROM THE UPPER 20S INLAND TO THE MID 30S AT THE BEACHES WITH
A FEW MID 20S LIKELY IN SOME SHELTERED AREAS OF FAR INTERIOR
SOUTHEAST GEORGIA.
MONDAY...SURFACE HIGH PRESSURE AND SHORTWAVE RIDGING ALOFT WILL
QUICKLY FOLLOW IN THE WAKE OF THE DEPARTING UPPER TROUGH EARLY IN
THE DAY. MODEL FORECAST SOUNDINGS INDICATE DEEP LAYER DRY AIR DURING
THE DAYTIME HOURS WITHIN A PREDOMINANT WEST/NORTHWEST FLOW. HIGH
LEVEL CLOUDS COULD THEN SHIFT INTO THE AREA OVERNIGHT DOWNSTREAM OF
A DEVELOPING LOW IN THE LOWER MISSISSIPPI/TENNESSEE VALLEYS. RISING
HEIGHTS ALOFT AND MOSTLY CLEAR TO PARTLY CLOUDY SKIES WILL SUPPORT
MODERATING TEMPERATURES...WITH HIGHS REACHING THE UPPER 50S TO LOWER
60S AWAY FROM THE LOCALLY COOLER COASTLINE. LOW LEVEL FLOW WILL BACK
TO THE SOUTHWEST OVERNIGHT...AND WITH EVIDENCE OF SOME HIGHER LEVEL
CLOUDS PROVIDING INSULATING EFFECTS AFTER MIDNIGHT...EXPECT LOW
TEMPERATURES TO BE NEARLY 10 DEGREES WARMER THAN THE PREVIOUS NIGHT.
LOWS WILL THUS RANGE FROM THE UPPER 30S INLAND TO THE LOWER 40S NEAR
THE BEACHES.
TUESDAY...A POTENT SHORTWAVE TROUGH WILL DESCEND FROM THE NORTHERN
PLAINS STATES INTO THE MID MISSISSIPPI VALLEY THROUGH THE AFTERNOON
HOURS...PROVIDING SIGNIFICANT ENERGY TO ORGANIZE AND INTENSIFY A
SURFACE LOW SYSTEM OVER THE TENNESSEE VALLEY BY SUNSET. THE UPPER
TROUGH WILL DEVELOP INTO A CUT OFF LOW OVERNIGHT...AT THE SAME TIME
THAT THE SURFACE SYSTEM BECOMES MORE COMPLEX AND TRACKS DUE
EASTWARD THROUGH THE CAROLINAS AND MID ATLANTIC STATES BY DAYBREAK
WEDNESDAY. THE FORECAST AREA WILL BE LOCATED WITHIN THE WARM
SECTOR OF THE SYSTEM DURING THE DAYTIME HOURS TUESDAY...WITH
SOUTHERLY FLOW SUPPORTING TEMPERATURES RISING INTO THE UPPER 60S
NORTHWEST ZONES TO THE LOWER 70S SOUTH OF THE SAVANNAH RIVER. WITH
THE FORECAST AREA INITIALLY LOCATED SOUTH OF THE WARM FRONT AND
WEST OF THE APPROACHING COLD FRONT...EXPECT RAIN TO BE SLOW TO
PUSH INTO THE REGION THROUGH THE AFTERNOON HOURS. RAIN CHANCES
WILL THEN INCREASE SIGNIFICANTLY AFTER SUNSET ONCE THE FRONT AND
UPPER LOW PASS OVER THE SOUTHEAST AND MID ATLANTIC STATES. GIVEN
DECENT MODEL AGREEMENT IN POTENTIAL AND COVERAGE OF RAIN...HAVE
INCREASED POPS INTO THE LIKELY RANGE FOR MUCH OF THE FORECAST AREA
FROM AROUND MIDNIGHT TO DAYBREAK WEDNESDAY MORNING. THICK
INSULATING CLOUD COVER...ALONG WITH SOUTHERLY FLOW VEERING TO THE
WEST...WILL KEEP LOW TEMPERATURES TUESDAY NIGHT RATHER MILD IN THE
UPPER 40S TO LOWER 50S.
WEDNESDAY...THE STACKED AND INTENSIFYING LOW SYSTEM WILL LIFT
EAST/NORTHEAST DURING THE MORNING HOURS...WHILE THE TRAILING COLD
FRONT RAPIDLY MOVES OFFSHORE. RAIN CHANCES WILL BE DECREASING FROM
WEST TO EAST INTO THE EARLY AFTERNOON...AND WITH THE SURFACE LOW
DISPLACED NORTH OF THE FORECAST AREA BY DAYBREAK...WRAP AROUND
MOISTURE DOES NOT APPEAR TO BE A CONCERN AT THIS TIME. HIGH
TEMPERATURES WILL BE COOLER IN THE UPPER 50S TO LOWER 60S BEHIND
THE DEPARTING COLD FRONT...HOWEVER MODERATE TO STRONG
OFFSHORE/DOWNSLOPE FLOW AND LINGERING CLOUD COVER WILL MITIGATE
MORE SIGNIFICANT COOLING POTENTIAL. A GREATLY TIGHTENED PRESSURE
GRADIENT ON THE BACKSIDE OF THE SURFACE LOW...AS WELL AS COLD
ADVECTION ENHANCING MIXING INTO A 30 TO 40 KT LOW LEVEL
JET...SUGGESTS BREEZY TO GUSTY WEST WINDS DURING THE AFTERNOON
HOURS.
LAKE WINDS...WINDS WILL APPROACH ADVISORY CRITERIA TUESDAY
AFTERNOON AS A 40 KT LOW LEVEL JET PASSES OVER THE REGION.
HOWEVER...MIXING WILL BE LIMITED WITHIN A WARM ADVECTION REGIME
OVER THE COOLER LAKE WATERS. A BETTER CHANCE FOR LAKE WIND
ADVISORY THRESHOLDS TO BE MET IS ON WEDNESDAY...AS A SIGNIFICANTLY
TIGHTENED PRESSURE GRADIENT AND STRONG COLD ADVECTION ENHANCES
MIXING AND SUPPORTS 20 TO 25 KT WINDS OVER THE LAKE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS THE POTENT LOW SYSTEM RAPIDLY TRACKS INTO THE ATLANTIC THROUGH
THE LATE WEEK PERIOD...SURFACE HIGH PRESSURE AND UPPER LEVEL
RIDGING WILL FOLLOW IN ITS WAKE. EXPECT DRY CONDITIONS TO THUS
PREVAIL THURSDAY THROUGH THE WEEKEND. RISING HEIGHTS ALOFT WILL
SUPPORT A GRADUAL WARMING TREND THROUGH THE PERIOD...WITH
TEMPERATURES PEAKING IN THE LOW TO MID 60S THURSDAY AND
FRIDAY...THEN POSSIBLY THE LOW 70S SATURDAY AND SUNDAY. LOW
TEMPERATURES WILL ALSO MODERATE INTO THE UPPER 30S TO LOWER 40S BY
LATE PERIOD.
&&
.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
VFR.
EXTENDED AVIATION OUTLOOK...LOW TO MODERATE CHANCE OF REDUCED
CEILINGS/VISIBILITIES AT TIMES LATE TUESDAY INTO WEDNESDAY. WINDY
CONDITIONS WILL ALSO IMPACT THE TERMINALS TUESDAY AFTERNOON
THROUGH THURSDAY.
&&
.MARINE...
THIS MORNING...WINDS REMAIN QUITE RISKY AT BUOY 41008 WHICH IS A
BIT HIGHER THAN THE LATEST RAP RUN. WILL EXTEND THE SMALL CRAFT
ADVISORY FOR BOTH GEORGIA LEGS UNTIL 8 AM.
TODAY...WINDS WILL SLOWLY SUBSIDE ACROSS THE MARINE AREA TODAY AS
COLD AIR ADVECTION STEADILY WANES. ONCE THE MORNING SURGE
CEASES...EXPECT WINDS TO SETTLE INTO THE 10-15 KT RANGE...EXCEPT
15-20 KT OVER THE GEORGIA OFFSHORE WATERS. SEAS WILL RANGE FROM
2-3 FT NEARSHORE WATERS AND 3-4 FT OFFSHORE WATERS
TONIGHT...ANOTHER SURGE LOOKS LIKELY OVER THE WATERS TONIGHT AS
THE PRESSURE GRADIENT TIGHTENS A BIT AHEAD OF HIGH PRESSURE
NUDGING IN FROM THE WEST. SHOULD SEE AT LEAST FREQUENT GUSTS TO 25
KT OCCUR OVER THE WARMER WATERS ACROSS THE EASTERN PORTIONS FOR
THE GEORGIA OFFSHORE LEG...SO A SMALL CRAFT ADVISORY WILL LIKELY
BE NEEDED THERE. IT LOOKS A BIT MORE MARGINAL OVER THE NEARSHORE
WATERS SO WILL NOT HOIST AN ADVISORY JUST YET. SEAS WILL RANGE
FROM 2-4 FT NEARSHORE WATERS...4-6 FT OFFSHORE WATERS.
MONDAY...COLD ADVECTION WILL DIMINISH BY MID MORNING...AND ANY
SMALL CRAFT ADVISORIES SHOULD BE ALLOWED TO EXPIRE AT THAT TIME.
SOUTHERLY FLOW WILL THEN REMAIN BELOW ADVISORY THRESHOLDS FOR THE
REMAINDER OF THE DAY...AS HIGH PRESSURE BUILDS IN FROM FLORIDA AND
SETTLES OVER THE MARINE ZONES.
TUESDAY THROUGH THURSDAY...CONDITIONS WILL DETERIORATE AGAIN BY
LATER TUESDAY...AS ATLANTIC HIGH PRESSURE SHIFTS FARTHER AWAY FROM
THE MARINE ZONES AHEAD OF AN INTENSIFYING LOW PRESSURE SYSTEM
MOVING INTO THE TENNESSEE VALLEY. THE POTENT LOW SYSTEM WILL
INTENSIFY AS IT SHIFTS INTO THE CAROLINAS LATE TUESDAY/EARLY
WEDNESDAY AND THEN OFF THE MID ATLANTIC COAST WEDNESDAY
NIGHT/THURSDAY. A TRAILING COLD FRONT WILL SWEEP THROUGH THE
MARINE ZONES LATE TUESDAY NIGHT INTO EARLY WEDNESDAY. SMALL CRAFT
ADVISORY CRITERIA WILL BE REACHED BOTH AHEAD OF THE FRONT AND IN
ITS WAKE DURING THE MID WEEK PERIOD...WHILE THERE IS ALSO A GOOD
POTENTIAL FOR GALE CONDITIONS TO BE REACHED. WILL CONTINUE TO
MENTION THIS POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EST THIS MORNING FOR AMZ354-
374.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
701 AM EST SUN MAR 3 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 511 AM EST SUN MAR 3 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OVER THE WRN CONUS AND
AND TROUGHING OVER THE EAST...RESULTING IN NW MID/UPPER LEVEL FLOW
FROM WRN CANADA THROUGH THE PLAINS INTO THE LOWER MS VALLEY. AT THE
SFC...A RIDGE EXTENDED FROM HUDSON BAY AND NW ONTARIO THROUGH WRN
LAKE SUPERIOR. IN PAST FEW HOURS...COMBINATION OF SUBTLE TROUGHING
AND LOW-LVL CONVERGENCE OVER ERN LAKE SUPERIOR ALONG WITH THE INFLUX
OF SLIGHTLY MORE MOIST AIR AT LOW-LVLS FROM NE OF LAKE SUPERIOR AND
WEAK Q-VECT CONV HAS LEAD TO THE FORMATION OF LAKE CLOUDS AND LIGHT
-SHSN/FLURRIES FROM MARQUETTE EASTWARD AS NOTED ON IR SATELLITE AND
MQT RADAR LOOPS. CLEAR SKIES AND LIGHT WINDS UNDER SFC RDG AXIS HAVE
ALLOWED TEMPS TO DROP WELL BLO ZERO AT MANY LOCATIONS EARLY THIS
MORNING. LOWEST READINGS THUS FAR HAVE BEEN -9F AT KIWD...-4F AT
KCMX AND -2F AT NWS MQT. LAND O LAKES JUST SOUTH OF WATERSMEET HAS
PLUMMETED TO -13F.
TODAY...SIMILAR TO YESTERDAY...EXPECT CLOUDS AND ASSOC LES TO
GENERALLY DISSIPATE BY LATE MORNING/EARLY AFTERNOON AS LOW-LVL
CONVERGENCE WEAKENS AND Q-VECT DIVERGENCE SPREADS IN FROM THE WEST
WITH ADVANCING MID-LVL RDG. EXPECT MAX TEMPERATURES AGAIN SIMILAR TO
YESTERDAY WITH HIGHS RANGING FROM THE LOWER 20S NORTH CENTRAL AND
EAST TO THE MID TO UPPER 20S ELSEWHERE.
NOT AS CONFIDENT ON DEVELOPMENT OF LAKE EFFECT CLOUDS TONIGHT AS
MODEL FCST SNDGS SHOW SUBSIDENCE INVERSION CRASHING TOWARD SFC WITH
STRONG AMPLIFIED RDG MOVING OVER THE AREA. THIS IS ALSO WELL
DEPICTED ON SNDGS WITH STRONG MID-LVL DRYING AND Q-VECT DIV. LOW-LVL
WINDS ARE ALSO GENERALLY MORE DIFLUENT...ALTHOUGH THERE IS STILL
SOME SUBTLE TROFFING AND WEAKLY CONVERGENT NNE FLOW FROM EASTERN
LAKE SUPERIOR INTO NCNTRL COUNTIES...ESPECIALLY ERN MQT AND WRN
ALGER. HAVE TRIMMED BACK POPS SOME FROM PREV FCST DUE TO
AFOREMENTIONED NEGATIVE FACTORS FOR LES...BUT WILL KEEP SOME SLIGHT
CHC POPS OVER ERN MQT/WRN ALGER IN CASE SOME LIGHT LES/FLURRIES CAN
BE INITIATED THERE DUE TO WEAK LOW-LVL CONVERGENCE. EXPECT SOME
SUB-ZERO LOW TEMPS AGAIN OVER THE FAR WRN INTERIOR UNDER CLEAR SKIES
AND LIGHT WINDS OF SFC RDG AXIS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 511 AM EST SUN MAR 3 2013
SOME LIGHT LINGERING LES WILL CONTINUE ON MON IN NE LOW LEVEL FLOW
AS SFC AND UPPER LEVEL RIDGING MOVES IN. GIVEN MARGINAL TEMPS FOR
LES AND OVERALL CONDITIONS THAT WILL BE DETRIMENTAL TO LES...ONLY
SLIGHT CHANCE POPS WILL BE MAINTAINED ON MON.
CONDITIONS BECOME MORE FAVORABLE FOR LES TUE INTO WED AS AN UPPER
TROUGH MOVES OVER THE REGION...BRINGING COLDER INVERSION TEMP TEMPS
AROUND -13C AT 900MB...BETTER MOISTURE AND CYCLONIC FLOW. LOW LEVEL
WINDS WILL CONTINUE TO BE OUT OF THE NE-N...SO THE MOST FAVORED
AREAS WILL BE OVER THE HIGHER TERRAIN OF N CENTRAL UPPER MI. COULD
SEE A FEW INCHES OF ACCUMULATION...BUT NOT EXPECTED TOO LARGE OF
AMOUNTS GIVEN MORE MARGINAL INVERSION TOP TEMPS.
THERE ARE TIMING DIFFERENCES BETWEEN MODELS...BUT THEY DO AGREE ON
THE GENERAL IDEA OF BRINGING A SFC HIGH FOLLOWED BY UPPER RIDGING ON
OR AROUND THU. A SERIES OF SHORTWAVE TROUGHS ARE FORECAST TO MOVE
NEARBY FRI AND SAT...BUT NOT SIGNIFICANT PRECIP IS EXPECTED AT THIS
TIME AND CONFIDENCE IS LOWER GIVEN LIMITATION OF NWP WITH THESE
FEATURES THAT FAR OUT.
TAKING A QUICK LOOK AT SFC TEMPS THROUGH THE LONG TERM /SINCE THERE
IS LITTLE ELSE TO TALK ABOUT/...HIGHS MON ARE FORECAST TO BY AROUND
30...AND SHOULD THEN DROP A FEW DEGREES FOR TUE BEFORE SIMILAR TEMPS
COME BACK ON WED. THU SHOULD SEE HIGHS AOA FREEZING IN MOST
LOCATIONS...WITH EVEN WARMER HIGHS IN THE MID TO UPPER 30S ON FRI
AND SAT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 653 AM EST SUN MAR 3 2013
EXPECT VFR CONDITIONS AT THE TAF SITES WITH THE EXCEPTION OF SOME
MVFR LAKE CLOUDS/FLURRIES AT KSAW THIS MORNING. MID-UPPER LEVEL RIDGE
BUILDING OVER THE REGION AND ASSOC DRYING WILL BE MORE PROHIBITIVE
FOR LAKE CLOUDS AND FLURRIES TO FORM TONIGHT DESPITE WEAK NNE FLOW...SO
HAVE DECIDED TO MAINTAIN VFR CONDITIONS THROUGH TONIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 511 AM EST SUN MAR 3 2013
WINDS LESS THAN 20 KTS THROUGH MONDAY...THEN EXPECT NORTHEAST WINDS
TO INCREASE TO 30 KTS OVER WEST AND NORTH CENTRAL SECTIONS BY MONDAY
NIGHT AS LOW PRESSURE SYSTEM MOVES BY TO THE SOUTH OVER THE NORTHERN
MISSISSIPPI RIVER VALLEY. WINDS 20-30 KTS CONTINUE OVER MOST OF LK
SUPERIOR THROUGH TUESDAY BEFORE SETTLING DOWN TO LESS 20 KTS BY
WEDNESDAY. WEAK PRES GRADIENT OVER AREA WILL MAINTAIN FAIRLY LIGHT
WINDS OF 20 KT OR LESS THROUGH THE REST OF THE WEEK.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
513 AM EST SUN MAR 3 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 511 AM EST SUN MAR 3 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OVER THE WRN CONUS AND
AND TROUGHING OVER THE EAST...RESULTING IN NW MID/UPPER LEVEL FLOW
FROM WRN CANADA THROUGH THE PLAINS INTO THE LOWER MS VALLEY. AT THE
SFC...A RIDGE EXTENDED FROM HUDSON BAY AND NW ONTARIO THROUGH WRN
LAKE SUPERIOR. IN PAST FEW HOURS...COMBINATION OF SUBTLE TROUGHING
AND LOW-LVL CONVERGENCE OVER ERN LAKE SUPERIOR ALONG WITH THE INFLUX
OF SLIGHTLY MORE MOIST AIR AT LOW-LVLS FROM NE OF LAKE SUPERIOR AND
WEAK Q-VECT CONV HAS LEAD TO THE FORMATION OF LAKE CLOUDS AND LIGHT
-SHSN/FLURRIES FROM MARQUETTE EASTWARD AS NOTED ON IR SATELLITE AND
MQT RADAR LOOPS. CLEAR SKIES AND LIGHT WINDS UNDER SFC RDG AXIS HAVE
ALLOWED TEMPS TO DROP WELL BLO ZERO AT MANY LOCATIONS EARLY THIS
MORNING. LOWEST READINGS THUS FAR HAVE BEEN -9F AT KIWD...-4F AT
KCMX AND -2F AT NWS MQT. LAND O LAKES JUST SOUTH OF WATERSMEET HAS
PLUMMETED TO -13F.
TODAY...SIMILAR TO YESTERDAY...EXPECT CLOUDS AND ASSOC LES TO
GENERALLY DISSIPATE BY LATE MORNING/EARLY AFTERNOON AS LOW-LVL
CONVERGENCE WEAKENS AND Q-VECT DIVERGENCE SPREADS IN FROM THE WEST
WITH ADVANCING MID-LVL RDG. EXPECT MAX TEMPERATURES AGAIN SIMILAR TO
YESTERDAY WITH HIGHS RANGING FROM THE LOWER 20S NORTH CENTRAL AND
EAST TO THE MID TO UPPER 20S ELSEWHERE.
NOT AS CONFIDENT ON DEVELOPMENT OF LAKE EFFECT CLOUDS TONIGHT AS
MODEL FCST SNDGS SHOW SUBSIDENCE INVERSION CRASHING TOWARD SFC WITH
STRONG AMPLIFIED RDG MOVING OVER THE AREA. THIS IS ALSO WELL
DEPICTED ON SNDGS WITH STRONG MID-LVL DRYING AND Q-VECT DIV. LOW-LVL
WINDS ARE ALSO GENERALLY MORE DIFLUENT...ALTHOUGH THERE IS STILL
SOME SUBTLE TROFFING AND WEAKLY CONVERGENT NNE FLOW FROM EASTERN
LAKE SUPERIOR INTO NCNTRL COUNTIES...ESPECIALLY ERN MQT AND WRN
ALGER. HAVE TRIMMED BACK POPS SOME FROM PREV FCST DUE TO
AFOREMENTIONED NEGATIVE FACTORS FOR LES...BUT WILL KEEP SOME SLIGHT
CHC POPS OVER ERN MQT/WRN ALGER IN CASE SOME LIGHT LES/FLURRIES CAN
BE INITIATED THERE DUE TO WEAK LOW-LVL CONVERGENCE. EXPECT SOME
SUB-ZERO LOW TEMPS AGAIN OVER THE FAR WRN INTERIOR UNDER CLEAR SKIES
AND LIGHT WINDS OF SFC RDG AXIS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 511 AM EST SUN MAR 3 2013
SOME LIGHT LINGERING LES WILL CONTINUE ON MON IN NE LOW LEVEL FLOW
AS SFC AND UPPER LEVEL RIDGING MOVES IN. GIVEN MARGINAL TEMPS FOR
LES AND OVERALL CONDITIONS THAT WILL BE DETRIMENTAL TO LES...ONLY
SLIGHT CHANCE POPS WILL BE MAINTAINED ON MON.
CONDITIONS BECOME MORE FAVORABLE FOR LES TUE INTO WED AS AN UPPER
TROUGH MOVES OVER THE REGION...BRINGING COLDER INVERSION TEMP TEMPS
AROUND -13C AT 900MB...BETTER MOISTURE AND CYCLONIC FLOW. LOW LEVEL
WINDS WILL CONTINUE TO BE OUT OF THE NE-N...SO THE MOST FAVORED
AREAS WILL BE OVER THE HIGHER TERRAIN OF N CENTRAL UPPER MI. COULD
SEE A FEW INCHES OF ACCUMULATION...BUT NOT EXPECTED TOO LARGE OF
AMOUNTS GIVEN MORE MARGINAL INVERSION TOP TEMPS.
THERE ARE TIMING DIFFERENCES BETWEEN MODELS...BUT THEY DO AGREE ON
THE GENERAL IDEA OF BRINGING A SFC HIGH FOLLOWED BY UPPER RIDGING ON
OR AROUND THU. A SERIES OF SHORTWAVE TROUGHS ARE FORECAST TO MOVE
NEARBY FRI AND SAT...BUT NOT SIGNIFICANT PRECIP IS EXPECTED AT THIS
TIME AND CONFIDENCE IS LOWER GIVEN LIMITATION OF NWP WITH THESE
FEATURES THAT FAR OUT.
TAKING A QUICK LOOK AT SFC TEMPS THROUGH THE LONG TERM /SINCE THERE
IS LITTLE ELSE TO TALK ABOUT/...HIGHS MON ARE FORECAST TO BY AROUND
30...AND SHOULD THEN DROP A FEW DEGREES FOR TUE BEFORE SIMILAR TEMPS
COME BACK ON WED. THU SHOULD SEE HIGHS AOA FREEZING IN MOST
LOCATIONS...WITH EVEN WARMER HIGHS IN THE MID TO UPPER 30S ON FRI
AND SAT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1250 AM EST SUN MAR 3 2013
DIFFICULT FORECAST CONTINUES WITH OFF AND ON AGAIN LAKE EFFECT
CLOUDS WITH NORTHERLY UPSLOPE DIRECTION CONTINUING. EACH
DAY...DIURNAL HEATING HAS MIXED OUT THE MVFR DECK WITH SOME DRIER
AIR. PERSISTENCE WITH THIS THEME WILL CONTINUE AT SAW AND CMX. VFR
CONDITIONS OVERNIGHT WILL BE REPLACED WITH THE MVFR CLOUDS
LATE TONIGHT AND THIS WILL LAST INTO SUN AFTERNOON BEFORE HEATING
AND MIXING AGAIN MIXES THIS LOW DECK BACK OUT. VFR CONDITIONS WILL
CONTINUE AT IWD THROUGH THE PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 511 AM EST SUN MAR 3 2013
WINDS LESS THAN 20 KTS THROUGH MONDAY...THEN EXPECT NORTHEAST WINDS
TO INCREASE TO 30 KTS OVER WEST AND NORTH CENTRAL SECTIONS BY MONDAY
NIGHT AS LOW PRESSURE SYSTEM MOVES BY TO THE SOUTH OVER THE NORTHERN
MISSISSIPPI RIVER VALLEY. WINDS 20-30 KTS CONTINUE OVER MOST OF LK
SUPERIOR THROUGH TUESDAY BEFORE SETTLING DOWN TO LESS 20 KTS BY
WEDNESDAY. WEAK PRES GRADIENT OVER AREA WILL MAINTAIN FAIRLY LIGHT
WINDS OF 20 KT OR LESS THROUGH THE REST OF THE WEEK.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...07
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
516 AM EST SUN MAR 3 2013
.SYNOPSIS...
STUBBORN UPPER LEVEL LOW CONTINUES TO BRING SNOW SHOWERS THROUGH
TONIGHT. HIGH PRESSURE CROSSES MONDAY. ANOTHER LOW PRESSURE
SYSTEM CROSSES TUESDAY THROUGH WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
BROAD UPPER TROUGH CONTINUES TO SPIN OVER THE NORTHEAST CONUS...WITH
ANOTHER DISTURBANCE ROTATING AROUND ITS BACKSIDE FROM NW TO SE TODAY.
12Z THIS MORNING AFOREMENTIONED UPPER LOW OVER NORTHEAST CENTERED
ROUGHLY OVER THE NYC AREA BUT WILL FINALLY BEGIN A SLOW EXODUS TO
THE EAST...PROGGED TO BE JUST SOUTH OF CAPE COD MASS BY 00Z SUN. AS
IT DOES SO...ONE FINAL S/W TROUGH WILL QUICKLY DROP SSE-WARD WITH
AXIS OVER WESTERN OHIO BY 18Z AND NEAR THE OHIO RIVER BY 00Z SUN.
LATEST NAM 03.00 RUN IN FACT ATTEMPTS TO BRIEFLY CLOSE THIS 500MB
LOW OFF BY THIS TIME. LARGE SCALE ASCENT PUSHES INTO THE WESTERN
ZONES BY 12Z AND IS MAXIMIZED OVER THE SOUTHERN ZONES AROUND 18Z. IN
ADDITION...A DECENT AREA OF POTENTIAL VORT ADVECTION PUSHES ACROSS
THE AREA AS WELL BTWN 18Z SAT AND 00Z SUN. AS WITH
YESTERDAY...AMOUNT OF LLVL MOISTURE IS SOMEWHAT IN QUESTION PER NAM
SOUNDINGS. RUC SOUNDINGS HOWEVER INDICATE A DEEPER SATURATED LLVL AS
IT DID YESTERDAY. WITH THIS IN MIND...EXPECT A DAY FAIRLY SIMILAR TO
YESTERDAY WITH OFF/ON FLURRIES AND SNOW SHOWERS. AS SUCH...WILL KEEP
AT LEAST SLIGHT CHANCE POPS GOING FOR THE AREA FOR MUCH OF THE
DAY...WITH THE USUAL HIGHER CHANCE POPS IN THE EASTERN HIGH COUNTRY.
ALSO LOWERED MAX TEMPS A BIT. DEPENDING ON MODEL OF CHOICE...925MB
TEMPS IDENTICAL OR A BIT COOLER THIS AFTERNOON VERSUS YESTERDAY AND
WITH THE EXPECTED CLOUD COVER AND FLURRIES AND/OR LIGHT SNOW
AROUND...TEMPS SHOULD BE ABOUT IDENTICAL TO YESTERDAY/S READINGS.
BY 00Z SUN TROUGH AXIS/POSSIBLE CUT OFF LOW NEAR THE OHIO RIVER WITH
THE LARGE SCALE FORCING FOR ASCENT EAST OF IT BUT EXITING THE
AREA...WHICH SHOULD EFFECTIVELY END PRECIP CHANCES FOR LOWLAND
LOCATIONS. TRAPPED LLVL MOISTURE IN THE USUAL FAVORED UPSLOPE AREAS
OF THE NORTHEAST MOUNTAINS SHOULD SEE AN INCREASE IN SNOWFALL
ACTIVITY DURING THE EVENING HOURS AS TROUGH WITH ASSOC LIFT MAKES
ITS WAY THROUGH. 850MB WIND TRAJECTORY OFF LAKE ERIE NOT THE BEST
BUT PRESENT NONETHELESS OFF THE WESTERN TIP. ANTICIPATE A GENERAL
INCH TO TWO INCHES FOR THIS AREA WITH LESSER AMOUNTS IN THE
VALLEYS...WITH THE SNOWFALL TAPERING OFF BY THE END OF THE PERIOD.
ACROSS THE LOWLANDS CLOUDS INTO THE OVERNIGHT HOURS WILL GIVE WAY TO
SOME PARTIAL CLEARING IN THE LATE HOURS TOWARDS DAWN. GIVEN THE
RELATIVELY LOW MAX TEMPS TODAY WITH LIGHT WINDS AND DEWPTS INTO THE
UPPER TEENS...LOWLAND MINS SHOULD HAVE NO TROUBLE FALLING TO AROUND
THE 20 DEGREE MARK BY DAWN MONDAY.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
HIGH PRESSURE PROVIDES WEAK PRESSURE GRADIENT AND WEAK OR CALM
FLOW MONDAY AND MONDAY NIGHT. DRY AND COLDER AIR ALOFT UNDER
NORTHWEST FLOW WILL PROVIDE SUBSIDENCE AND DRY WEATHER...AND
PROBABLY MOSTLY CLEAR SKIES THROUGH MONDAY EVENING.
HIGH LEVEL CLOUDS WILL INCREASE LATER MONDAY NIGHT...AHEAD OF A
SOUTHERN STREAM LOW PRESSURE SYSTEM. DIFFERENCES ARE NOTICEABLE
AMONG SYNOPTIC MODELS...WITH THE LOW CENTER LOCATION AND TRAJECTORY
BY 12Z TUESDAY...FROM EXTREME SOUTHWEST KY TO CENTRAL OH.
THEREFORE...CONFIDENCE IS LOW AT THIS TIME.
DESPITE OF DIFFERENT TRAJECTORY SOLUTIONS...ALL MODELS INJECT
WARM AND MOIST AIR ADVECTION UNDER SOUTHWESTERLY FLOW ON TUESDAY...TO
PRODUCE LIQUID PCPN AHEAD AND ALONG A WARM FRONT PASSAGE. ALL
MODELS ARE IN AGREEMENT WITH A WARM NOSE FROM H850 TO H900
SUGGESTING LIQUID PCPN ON TUESDAY. HOWEVER...AS THE LOW CONTINUES
ITS EAST NORTHEAST TRAJECTORY...WRAP AROUND COLDER AIR WILL BRING
THE MINUS 5C TEMPERATURE LINE ACROSS THE OUR CWA DURING THE
PREDAWN HOURS WEDNESDAY MORNING. THE NAM IS THE FASTER WITH THIS
FEATURE OVERHEAD BY 03Z WEDNESDAY. IT STILL UNCERTAIN WHETHER A
DRY SLOT WILL REDUCE PCPN BEHIND THE RAIN BATCH ASSOCIATED WITH
THE WARM FRONT...BEFORE THE REAL COLDER AIR MOVES IN AND CHANGES
WINTRY PCPN FROM MIX TO ALL SNOW BY WEDNESDAY MORNING 12-15Z.
HPC WWD SNOW ACCUMULATIONS GUIDANCE LOOKS TOO GENEROUS WITH 8-10
INCHES OF SNOW ACROSS NORTHEAST MOUNTAINS ENDING BY 12Z WEDNESDAY.
NOT EVEN THE SREF SUPPORT THIS PCPN TYPE CHANGING TO ALL SNOW BY
THIS TIME. BELIEVE...THE RAIN TO SNOW TRANSITION WILL OCCUR EARLY
WEDNESDAY MORNING...AND THE HEAVIEST SNOW AMOUNTS THROUGH THE
AFTERNOON AND EVENING HOURS. THEREFORE...KEPT MENTIONED OF
SIGNIFICANT HEAVY WET SNOW IN HWO AND SYN PRODUCTS FROM PREVIOUS
FORECAST PACKAGE.
A BLEND BETWEEN MAV AND MET GUIDANCE RESEMBLES PREVIOUS
TEMPERATURES THROUGH THE PERIOD. THEREFORE...MADE MINOR TWEAKS
HERE AND THERE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
THE MARCH LION WILL BE ROAMING OUR AREA EARLY IN THE EXTENDED. THE
AMERICAN MODELS CONTINUE TO BE A BIT FASTER WITH THE CLOSED 500 MB
LOW MOVING EAST...OUT OF THE MID MISSISSIPPI VALLEY OR LOWER OHIO
VALLEY ON TUESDAY EVENING...COMPARED TO THE ECMWF. BUT THE 12Z
ECMWF SEEMS TO BE CATCHING UP.
ALL THE MODELS CONTINUE TO AGREE...THE 500 MB LOW PASSES TO OUR
SOUTH...PROBABLY OVER THE SMOKY MOUNTAINS AROUND 12 WEDNESDAY...
THEN NEAR THE NC OUTER BANKS AT 00Z THURSDAY. PICTURING THIS SYSTEM
TO BE STRONG ENOUGH TO BACK THE 700 MB FLOW AND THROW THE DEEPER
MOISTURE W/NW AS THE COLUMN COOLS LATE TUESDAY NIGHT AND EARLY
WEDNESDAY MORNING. AS A RESULT...FORECASTING THE POSSIBILITY OF
HEAVY WET SNOW OVER THE MOUNTAINOUS COUNTIES...ESPECIALLY WV
MOUNTAIN COUNTIES. HAVE INTRODUCED A HAZARD IN OUR HAZARDOUS
WEATHER POTENTIAL...FOR HEAVY WET SNOW...WATCH/WARNING STUFF FOR THE
WV MOUNTAIN COUNTIES...INCLUDING THE BKW/EKN VCNTY. EVEN...THE
LOWLAND COUNTIES COULD HAVE SOME LESSER ACCUMULATIONS WITH SOME
ADVISORIES.
WILL LEAVE HIGHER POPS LONGER THAN GUIDANCE AND PREVIOUS FORECAST
FOR WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING...BUT A STRONG POP
GRADIENT OVER THE OHIO VALLEY COUNTIES.
THE MARCH ENVIRONMENT FINALLY SETTLES DOWN FOR THURSDAY INTO
SATURDAY. A WEAK FEATURE MAY SAG DOWN FROM THE NORTH ON SATURDAY
AFTERNOON AND NIGHT.
&&
.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
PREDOMINANTLY MVFR CIGS PREVAIL IN THE CONTINUED W TO NW FLOW OF
COLD AIR...WITH OCCASIONAL LOW VFR CIGS OVERNIGHT. IFR CIGS
EXPECTED TO BECOME MORE PREVALENT LATE OVERNIGHT THROUGH DAWN
SUNDAY. VSBY RESTRICTIONS IN SCATTERED SNOW SHOWERS WILL TEND TO
BECOME MORE CONFINED TO THE MOUNTAINS OVERNIGHT WITH MVFR
INTERSPERSED WITH BRIEF IFR IN A HEAVIER SNOW SHOWER.
SUNDAY WILL BRING MODEST IMPROVEMENT WITH STRATOCU CIGS GETTING TO
VFR BY AFTERNOON FOR LOWLAND LOCATIONS...WITH EASTERN MOUNTAIN
LOCATIONS REMAINING MVFR. EXPECT SNOW SHOWERS IN THE MOUNTAINS TO
WIND DOWN SOMEWHAT BY MIDDAY BUT PICK UP ONCE AGAIN BY AND AFTER
00Z MON.
LIGHT W TO NW SFC FLOW WITH LIGHT TO MODERATE NW FLOW ALOFT CONTINUES
THROUGH THE PERIOD.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY...
FORECAST CONFIDENCE...MEDIUM.
ALTERNATE SCENARIOS: TIMING OF SNOW AND ASSOCIATED RESTRICTIONS MAY
VARY. TIMING OF CEILING CATEGORY CHANGES MAY ALSO VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE SUN 03/03/13
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
CRW CONSISTENCY H H H H M H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY M M M M M M L L M H H H
EKN CONSISTENCY M M M L L L L L L L L L
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY L L L L L L L L L L H H
AFTER 12Z MONDAY...
IFR VISIBILITIES AND CEILINGS POSSIBLE IN RAIN/SNOW TUESDAY THROUGH
WEDNESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/50
NEAR TERM...50
SHORT TERM...ARJ
LONG TERM...KTB
AVIATION...50
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
530 AM CST SUN MAR 3 2013
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
325 AM CST SUN MAR 3 2013
MAIN FOCUS IS ON THE LONG PERIOD OF ACCUMULATING SNOW LATE TONIGHT
THROUGH TUESDAY
CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT
ANALYSIS SHOWED A POTENT SHORTWAVE TROUGH OVER SOUTHERN BRITISH
COLUMBIA INTO WASHINGTON STATE...RIDGING FROM BAJA CALIFORNIA INTO
SOUTHERN SASKATCHEWAN...AND A SHORTWAVE TROUGH DROPPING INTO EASTERN
WISCONSIN. PLENTIFUL UPPER LEVEL MOISTURE WAS STREAMING NORTH OUT OF
THE TROPICAL EAST PACIFIC AND THROUGH THE TOP OF THE UPPER RIDGE...
MANIFESTING ITSELF AS CIRRUS CLOUD COVER OVER THE DAKOTAS INTO
WESTERN MINNESOTA. EAST OF THIS CIRRUS...AN ALTOSTRATUS DECK WAS
PRESENT ACROSS MUCH OF MINNESOTA AND IOWA. THIS DECK IS A RESULT OF
RELATIVELY HIGHER MOISTURE OVER THE DAKOTAS GETTING ISENTROPICALLY
LIFTED. 00Z SOUNDING DATA SHOWED PRECIPITABLE WATER OF 0.16 INCHES
AT MPX...OR 66 PERCENT OF NORMAL...COMPARED TO 0.4 INCHES AT BIS AND
ABR OR 175 PERCENT OF NORMAL. BIG 850MB TEMPERATURE DIFFERENCE
TOO...WITH MPX AT -8C COMPARED TO AROUND 3C AT BIS AND ABR. DESPITE
THE PRESENCE OF THE ALTOSTRATUS DECK AND SOME LIGHT RETURNS ON
REGIONAL RADAR...NOTHING HAS REACHED THE SURFACE DUE TO DRIER LOW
LEVEL AIR SEEN ON THAT 00Z MPX SOUNDING. DRY AIR SEEN ON THE 00Z GRB
SOUNDING HAS ALSO PREVENTED MUCH FOR CLOUDS WITH THE SHORTWAVE
DROPPING THROUGH EASTERN WISCONSIN. AT THE SURFACE...A RIDGE OF HIGH
PRESSURE ENCOMPASSED MUCH OF THE WESTERN GREAT LAKES WHILE LOW
PRESSURE WAS DEEPENING IN SOUTHERN ALBERTA. LASTLY...REGARDING THAT
POTENT SHORTWAVE TROUGH...00Z RAOB DATA SHOWED SOME PRETTY
IMPRESSIVE 500MB HEIGHT FALLS...AROUND 100 METERS IN 12 HOURS.
ALL MODELS CONTINUE TO INDICATE THAT THE LONG PERIOD OF SNOW WILL
OCCUR FROM THE NORTHERN PLAINS SOUTHEAST INTO PORTIONS OF THE
FORECAST AREA. THREE DISTINCT FORCING MECHANISMS ARE GOING TO GOVERN
THIS SNOW...WITH THE LAST TWO ITEMS MODULATING THE INTENSITY AND
PLACEMENT...
1. A LOW TO MID LEVEL FRONTOGENESIS ZONE...WHICH CAN ALREADY BE SEEN
IN THE 00Z SOUNDING DATA NOTED BY THE SHARP DIFFERENCE IN 850MB
TEMPS BETWEEN MPX AND ABR.
2. A HARD TO SEE SHORTWAVE ON WATER VAPOR CURRENTLY IN SOUTHERN
IDAHO PROGGED TO MOVE WEST TO EAST THROUGH THE FORECAST AREA ON
MONDAY
3. THE POTENT UPPER TROUGH WHICH DROPS SOUTHEAST OUT OF THE NORTHERN
PLAINS ON MONDAY AND INTO THE MID-MISSISSIPPI VALLEY BY LATE TUESDAY
OVERALL...MODELS AGREE REALLY WELL TONIGHT INTO MONDAY IN THE
HANDLING OF THE FRONTOGENESIS ZONE AND SHORTWAVE MOVING THROUGH.
BETWEEN 00-06Z TONIGHT...SOUTH WINDS REALLY PICK UP ON THE 285-290K
SURFACES IN SOUTHWEST MINNESOTA AHEAD OF THE APPROACHING
SHORTWAVE...HELPING TO INCREASE THE INTENSITY OF THE FRONTOGENESIS
ZONE. COMBINED WITH PACIFIC MOISTURE ALREADY PRESENT IN THE
DAKOTAS...SNOW SHOULD EASILY BREAK OUT. AS THE SHORTWAVE PRESSES
EAST TOWARDS THE AREA AFTER 06Z...THE FRONTOGENESIS ZONE SHIFTS EAST
WITH IT...IMPACTING LOCATIONS WEST OF THE MISSISSIPPI RIVER. HIGHER
HORIZONTAL RESOLUTION QPF DATA FROM THE 03.00Z NAM...HIRES-ARW/NMM
AND REGIONAL CANADIAN SUGGEST ANYWHERE FROM 0.25-0.30...HIGHEST IN
THE AUSTIN/CHARLES CITY AREA. EVEN HIGHER AMOUNTS LOOK POSSIBLE TO
THE NORTHWEST. SOUNDINGS DEPICT ONLY A 75MB LAYER OF DENDRITIC
GROWTH...WAY UP AROUND 600MB...WITH LIFT THROUGHOUT A LOT OF THE
COLUMN. THUS...THINKING SNOW TO WATER RATIOS SHOULD STAY AROUND 10
TO 1...YIELDING UPWARDS OF 2-3 INCHES BY 12Z. THE FRONTOGENESIS ZONE
CONTINUES TO PUSH EAST DURING THE DAY MONDAY BY THE SHORTWAVE...
EVENTUALLY STALLING OUT OVER THE SOUTHWEST 2/3 OF THE FORECAST AREA
FOR THE AFTERNOON. THE HEAVIEST PRECIPITATION LOOKS TO OCCUR IN THE
MORNING WITH ENHANCEMENT FROM THE SHORTWAVE BEFORE THE SHORTWAVE
LIFTS OFF. COULD SEE UPWARDS OF 0.25 INCH DURING THE MORNING IN
SOUTHEAST MN INTO PORTIONS OF NORTHEAST IOWA...EQUATING TO ANOTHER
2-3 INCHES OF SNOW. THUS...FOR THE 06-18Z MONDAY PERIOD...TOTALS OF
4-5 INCHES SEEM EASILY POSSIBLE ALONG/WEST OF A LINE FROM ROCHESTER
MN TO OELWEIN IA. FARTHER EAST...WITH PRECIPITATION TAKING LONGER TO
SPREAD IN...MUCH LIGHTER AMOUNTS ARE ANTICIPATED...ESPECIALLY IN THE
DRIER AIR NORTHEAST OF I-94.
MONDAY NIGHT AND TUESDAY IS A LITTLE MORE PROBLEMATIC BECAUSE MODELS
HAVE STRUGGLED WITH THE POTENT UPPER TROUGH. EVEN TODAY...THERE ARE
QUESTIONS ON HOW MUCH EASTERLY MOVEMENT THE CORE OF THE UPPER TROUGH
WILL HAVE AS IT COMES OUT OF THE DAKOTAS. THE 03.00Z/06Z NAM REMAIN
THE FARTHEST EAST...TRACKING ACROSS CENTRAL/EASTERN IOWA TUESDAY
MORNING. ON THE OTHER END OF THE SPECTRUM IS THE 03.00Z UKMET...
DROPPING INTO NORTHEAST KANSAS AT THE SAME TIME. THE 03.00Z
GFS/CANADIAN/ECMWF ARE IN THE MIDDLE...TRACKING ACROSS FAR WESTERN
IOWA INTO NORTHWEST MISSOURI. OVERALL...THERE HAS BEEN A SHIFT EAST
WITH THE TRACK OVER THE PAST FEW MODEL RUNS...PUTTING MORE OF THE
FORECAST AREA INTO PRECIPITATION. AS SUCH...HAVE INCREASED AND
EXPANDED PRECIPITATION CHANCES FARTHER EAST. THE SETUP FOR MONDAY
NIGHT AND TUESDAY LOOKS MORE IMPRESSIVE DUE TO STRONGER DPVA FORCING
THE UPPER TROUGH. A NICE TROWAL SHOULD DEVELOP AS WELL ON THE
NORTHEAST SIDE OF THE UPPER TROUGH. ON TOP OF THIS...THE UPPER LOW
BRINGS IN COLDER AIR...POTENTIALLY RESULTING IN A DEEPER DENDRITIC
GROWTH ZONE. IN ANY EVENT...THE COLDER WILL CAUSE SNOW RATIOS TO
INCREASE. FOR BOTH QPF AND SNOW RATIOS...TOOK A MODEL CONSENSUS...
WHICH YIELDS ABOUT 6 TO 8 INCHES OF SNOWFALL SOUTHWEST OF I-94 OVER
THE MONDAY NIGHT AND TUESDAY PERIOD. THESE COULD EASILY BE HIGHER...
AS WELL AS EITHER SHIFTED EAST OR WEST DEPENDING ON THE EXACT UPPER
LOW TRACK.
REGARDING HAZARDS...WITH THE SHIFT EAST IN THE MONDAY NIGHT/TUESDAY
PERIOD...AN EXPANSION OF THE WATCH IS REQUIRED TO INCLUDE FROM
BUFFALO COUNTY SOUTHEAST TO GRANT COUNTY WI. CONVERTING THE EXISTING
WATCH TO WARNING OR ADVISORY ELSEWHERE IS VERY DIFFICULT AT THIS
TIME. ALTHOUGH MODELS AGREE WELL ON THE TONIGHT/MONDAY PERIOD...AT
MOST IT APPEARS A 12 HOUR PERIOD OF 3-5 INCHES WITH A 24 HOUR TOTAL
OF UP TO 6 INCHES...ALL BELOW WARNING CRITERIA. IMPACT WISE...THE
MORNING COMMUTE ACROSS SOUTHEAST MN AND NORTHEAST IOWA
DEFINITELY WILL BE AFFECTED...BUT THE SNOWFALL RATE RIGHT NOW DOES
NOT LOOK HIGH ENOUGH TO JUSTIFY A WARNING. OVER THE COURSE OF THE
ENTIRE PERIOD THROUGH TUESDAY...LOCATIONS ACROSS SOUTHEAST MINNESOTA
INTO NORTHEAST IOWA COULD PICK UP UPWARDS OF 10-15 INCHES...BUT THIS
IS OVER A 42 HOUR TIMEFRAME...WHICH MEANS SOME MELTING/SETTLING WILL
OCCUR. IN ADDITION...THE MONDAY NIGHT/TUESDAY PERIOD HAS GOT A LOT
OF UNCERTAINTY WITH THE UPPER TROUGH TRACK. THUS...AFTER
COLLABORATION WITH MPX...DMX AND DVN...HAVE LEFT THE WATCH INTACT
FOR NOW. CONVERSIONS TO WARNINGS AND/OR ADVISORIES WILL LIKELY TAKE
PLACE DURING THE DAY.
PRECIPITATION LOOKS TO TAIL OFF PRETTY QUICK TUESDAY NIGHT AS THE
UPPER TROUGH HEADS OFF TO THE MID-ATLANTIC REGION. DID PUT A 20
PERCENT CHANCE IN FOR THE EVENING ACROSS MUCH OF THE AREA WITH
SUGGESTIONS THE COLD CONVEYOR BELT MAY STILL BE AFFECTING US.
.LONG TERM...WEDNESDAY THROUGH SATURDAY NIGHT
325 AM CST SUN MAR 3 2013
AFTER AN ACTIVE SHORT TERM PERIOD...THE LONG TERM LOOKS MAINLY QUIET
WITH A PATTERN SHIFT STILL PROGGED TO OCCUR. A DEEP TROUGH IS
PROGGED TO MOVE INTO THE WESTERN U.S. WEDNESDAY INTO THURSDAY...
CAUSING RIDGING TO SHIFT EAST AND BUILD DOWNSTREAM TOWARDS THE
FORECAST AREA. SUBSIDENCE UNDER THE UPPER RIDGE COMBINED WITH HIGH
PRESSURE COMING THROUGH AT THE SURFACE WILL YIELD DRY AND LIKELY
MOSTLY SUNNY DAYS. 850MB TEMPS WARM AS WELL...ALLOWING HIGHS TO
CLIMB BACK TO NORMAL LEVELS BY THURSDAY.
FOR THURSDAY NIGHT AND HEADING INTO THE WEEKEND...THE WESTERN TROUGH
LOOKS TO SPLIT INTO TWO...WITH THE BULK OF IT CLOSING OFF INTO AN
UPPER LOW IN THE DESERT SOUTHWEST. THE NORTHERN STREAM PORTION OF
THIS TROUGH IS FORECAST TO HEAD UP INTO NORTHERN ONTARIO ON
FRIDAY...BRINGING A WEAKENING COLD FRONT THROUGH THE AREA. FOLLOWED
THE CONSENSUS WHICH HAD A 20 PERCENT CHANCE UP IN NORTHERN WISCONSIN
FOR FRIDAY. 20 PERCENT CHANCES ARE ALSO IN THE FORECAST FOR FRIDAY
NIGHT EVERYWHERE...ASSOCIATED WITH POSSIBLE WEAK FRONTOGENESIS IN
THE WAKE OF THE FRONTAL PASSAGE. DRIER WEATHER FOLLOWS FOR
SATURDAY...THOUGH THE LATEST 03.00Z ECMWF TRIES TO MAINTAIN THE
FRONTOGENESIS AND LIGHT PRECIPITATION. THUS...LATER FORECASTS MAY
NEED TO ADD SOME CHANCES IN FOR SATURDAY. TEMPERATURES BOTH FRIDAY
AND SATURDAY SHOULD END UP AT OR ABOVE NORMAL...EVEN WITH THE
PASSAGE OF THE WEAK COLD FRONT SINCE PACIFIC AIR IS FLOWING IN
BEHIND IT.
&&
.AVIATION...TODAY AND TONIGHT
530 AM CST SUN MAR 3 2013
BROKEN ALTOSTRATUS WILL MOVE ACROSS THE TAF SITES TODAY WITH CLOUD
BASES IN THE 6 TO 10 KFT RANGE. CEILINGS ARE EXPECTED TO LOWER
TONIGHT AS A STRONG LOW PRESSURE SYSTEM APPROACHES FROM THE
NORTHERN PLAINS. PLAN ON CEILINGS LOWERING TO 2500 FT AT KRST
AROUND 5 Z AT KRST AND AROUND 11Z AT KLSE. LIGHT SNOW WILL DEVELOP
AT KRST IN THE 10 TO 12Z TIMEFRAME WITH CEILINGS LOWERING TO 2SM
AND CEILINGS FALLING TO 700 FT. THE SNOW WILL SPREAD EAST AND
IMPACT KLSE AFTER 12Z MONDAY. A LONG PERIOD OF SNOW WILL OCCUR AT
THE TAF SITES MONDAY INTO TUESDAY WITH PERIODS OF IFR/LIFR
CONDITIONS EXPECTED. PLAN ON WINDS INCREASING OUT OF THE SOUTHEAST
LATE TONIGHT INTO MONDAY MORNING AS THE LOW DRAWS CLOSER. SOME
BLOWING SNOW COULD IMPACT KRST DURING THE DAY ON MONDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
325 AM CST SUN MAR 3 2013
WI...WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR WIZ032-033-041-053>055-061.
MN...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR MNZ079-086-087-094-095.
WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR MNZ088-096.
IA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR IAZ008-009-018-019.
WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
FOR IAZ010-011-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
433 AM MST SUN MAR 3 2013
.AVIATION...12Z TAFS
LOOK FOR LOWERING CLOUD BASES TODAY AS A COLD FRONT APPROACHES THE
AREA FROM THE NORTHWEST. LOW END MVFR LOOKS LIKELY AT KRWL THIS
AFTERNOON WITH LATEST HRRR MODEL EVEN FORECASTING THE CHANCE FOR
IFR CONDITIONS. FOR NOW...CONTINUED 1500 FOOT CEILINGS AT KRWL.
MORNING SHIFT WILL NEED TO MONITOR TRENDS FOR THE 18Z TAFS.
OTHERWISE...VFR EXPECTED WITH GUSRY WEST WINDS.
CLAYCOMB
&&
.PREV DISCUSSION... /ISSUED 321 AM MST SUN MAR 3 2013/
SHORT TERM...TODAY THROUGH TUESDAY...THE PRIMARY FORECAST CONCERN
IN THE SHORT TERM IS THE PACIFIC STORM SYSTEM AND ASSOCIATED COLD
FRONT FORECAST TO PUSH ACROSS WYOMING LATER TODAY AND TONIGHT.
THIS SYSTEM IS NOT EXPECTED TO PRODUCE MUCH PRECIPITATION FOR THE
LOWER ELEVATIONS OF SOUTHEAST WYOMING AND WESTERN NEBRASKA...BUT
WINDS WILL BE THE MAIN CONCERN THROUGH MONDAY. WEST TO SOUTHWEST
WINDS HAVE INCREASED EARLY THIS MORNING WITH THE ARLINGTON AREA
REPORTING GUSTS BETWEEN 50 TO 55 MPH...AND GUSTS BETWEEN 30 TO 40
MPH ELSEWHERE. WINDS NOT AS STRONG COMPARED TO WHAT WAS EXPECTED
24 HOURS AGO...BUT WILL KEEP THE HIGH WIND WARNING GOING FOR THE
WIND PRONE ZONES THROUGH TODAY. BASED ON 00Z MODELS...LOOKS LIKE
THE GRADIENT WILL DECREASE TONIGHT INSTEAD OF MONDAY MORNING...SO
THE WARNING MAY NEED TO BE CANCELLED EARLY. OTHERWISE...WESTERLY
WINDS WILL INCREASE OVER THE REST OF THE FORECAST AREA THIS
AFTERNOON DUE TO GOOD BOUNDARY LAYER MIXING. EXPECT WINDS TO STAY
BELOW HIGH WIND CRITERIA TODAY.
THE STRONG COLD FRONT WILL PUSH INTO SOUTHERN WYOMING TODAY.
ALTHOUGH DOWNSLOPE WINDS WILL RESULT IN MAINLY DRY WEATHER EAST OF
THE LARAMIE RANGE...MODELS SHOW GOOD UPSLOPE FLOW AND LLVL LIFT
ACROSS THE SIERRA MADRE RANGE AND SNOWY RANGE TODAY AND TONIGHT.
ISSUED A WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW
BEGINNING NOON TODAY THROUGH NOON MONDAY FOR THESE AREAS. EXPECT 6
TO 12 INCHES OF SNOW WITH MOST OF THE SNOW FALLING THIS AFTERNOON
THROUGH LATE THIS EVENING. ALTHOUGH 6 TO 8 INCH AMOUNTS ARE
EXPECTED TO BE WIDESPREAD...CAN NOT RULE OUT LOCALLY HIGHER
ACCUMULATIONS DUE TO LLVL INSTABILITY.
FOR MONDAY...UPPER LEVEL TROUGH WILL PUSH INTO THE WESTERN DAKOTAS
AS THE COLD FRONT SWINGS THROUGH THE REST OF THE FORECAST AREA
INTO COLORADO AND KANSAS. MUCH COLDER TEMPERATURES ARE EXPECTED ON
MONDAY WITH HIGHS IN THE 20S AND 30S ACROSS SOUTHEAST
WYOMING...AND AROUND 40 ACROSS WESTERN NEBRASKA EARLY IN THE
MORNING. THE MAIN CONCERN WILL BE STRONG WEST TO NORTHWEST WINDS.
GFS MOS SHOWS WINDS OVER 40 KNOTS SUSTAINED ACROSS WESTERN
NEBRASKA MONDAY AFTERNOON AFTER THE FRONT PUSHES ACROSS THE AREA.
HOWEVER...DID NOT ISSUE A HIGH WIND WATCH FOR WESTERN NEBRASKA
SINCE CONFIDENCE IS NOT THAT HIGH FOR WIND GUSTS OVER 58 MPH.
ALTHOUGH THERE IS A STRONG LLVL PRESSURE GRADIENT AND MODELS SHOW
WINDS AROUND 45 KNOTS AT 700 MB...THE SURFACE FRONT PUSHES ACROSS
THE AREA TOO EARLY AS THE RIGHT EXIT REGION OF THE JET DOES NOT
ENTER THE AREA UNTIL LATE MONDAY NIGHT. MODEL OMEGA SHOWS PEAK
SUBSIDENCE AND DOWNSLOPE AFTER 00Z TUESDAY ACROSS WESTERN NEBRASKA
WITH LITTLE SUBSIDENCE BEFORE 00Z. AT THIS TIME...A WIND ADVISORY
LOOKS MORE LIKELY FOR GUSTS AROUND 50 MPH. OTHERWISE...ANY LIGHT
SNOW SHOWERS OR FLURRIES WILL DISSIPATE MONDAY NIGHT ALONG WITH
SLOWLY DIMINISHING WINDS. THIS WILL LEAD TO COLD OVERNIGHT LOWS IN
THE SINGLE DIGITS AND TEENS DUE TO A VERY DRY AIRMASS OVER THE
FORECAST AREA. A SLOW WARMING TREND WILL BEGIN ON TUESDAY WITH
HIGH TEMPERATURES RETURNING TO THE 30S (WEST) AND 40S (EAST).
LONG TERM...TUESDAY NIGHT THROUGH SUNDAY
FORECAST CHALLENGE IN THE LONG TERM DEAL WITH PRECIP CHANCES NEXT
WEEKEND.
UPPER RIDGE LOOKS TO PASS OVER THE CWFA TUESDAY EVENING WITH
WARMING 700MB TEMPERATURES. GFS SHOWING +2C 700MB TEMPERATURES
INTO THE SOUTHERN NEBRASKA PANHANDLE WITH THE 0C LINE COVERING
MUCH OF SOUTHEAST WYOMING. LOOK FOR TEMPERATURES TO WARM BACK INTO
THE 60S ACROSS THE PANHANDLE WITH MID 40S WEST OF THE LARAMIE RANGE.
THESE WARM TEMPERATURES STAY WITH US THROUGH MUCH OF THE WEEK AS
700MB TEMPERATURES STAY FROM 0 TO +2C. ADDITIONALLY...WE ARE
LOOKING AT WINDY CONDITIONS AND DOWN SLOPING WESTERLY TO
SOUTHWESTERLY WINDS THAT WILL ADD TO THE WARM TEMPERATURES THROUGH
THURSDAY. LOOK FOR DAILY HIGHS SIMILAR TO WEDNESDAY WITH 60S IN
THE PANHANDLE AND 40S WEST OF THE LARAMIE RANGE.
THE WEATHER BEGINS TO CHANGE THURSDAY NIGHT INTO FRIDAY.
INITIALLY...FRONTAL PLACEMENT ON THE GFS AND ECMWF PRETTY
CONSISTENT...SHOWING A FRONT OVER NORTHWEST WYOMING...EXTENDING
SOUTHWEST INTO NEVADA. GFS CLOSES OFF AN UPPER LOW OVER SOUTHERN
NEVADA DURING THE DAY FRIDAY...WHILE THE ECMWF IS A LITTLE
SLOWER. GFS SHOWS A 1033MB SURFACE HIGH OVER EASTERN NORTH DAKOTA
PUSHING A BACKDOOR FRONTAL BOUNDARY INTO WESTERN SOUTH DAKOTA.
SHOULD BE SEEING SIGNIFICANT UPSLOPING DEVELOPING OVER THE
PANHANDLE AND EAST SLOPES OF THE LARAMIE RANGE DURING THIS TIME FRAME.
THE GFS TAKES THE UPPER LOW AND KEEPS IT SOUTH ACROSS ARIZONA AND
NEW MEXICO FOR SATURDAY. THE ECMWF ON THE OTHER HAND...EJECTS THE
LOW NORTHEASTWARD INTO WESTERN COLORADO WITH A SIGNIFICANT PRECIP
SHIELD DEVELOPING OVER MUCH OF THE CHEYENNE CWFA. SHOULD THE ECMWF
SOLUTION COME TRUE...WE ARE LOOKING AT A SIGNIFICANT WINTER
WEATHER EVENT AS QPFS ARE WELL OVER AN INCH. SHOULD THE GFS
SOLUTION COME TRUE...WE MAY MISS OUT ON PRECIP ALTOGETHER AS IT
PLACES ALL THE QPF OVER COLORADO.
WENT AHEAD AND INCREASED POPS TO SLIGHT CHANCE FOR MOST AREAS WITH
CHANCE POPS IN THE SNOWY AND SIERRA MADRE RANGES. HOPEFULLY OVER
THE NEXT COUPLE MODEL RUNS...WE CAN GET A LITTLE MORE CONSISTENCY
BETWEEN THE GFS AND ECMWF. ONE OTHER NOTE THOUGH...THE ECMWF HAS
BEEN SHOWING THIS NOW THE PAST 3-4 MODEL RUNS...SO WE WILL NEED TO
KEEP AN EYE ON THIS STORM DEVELOPING.
&&
FIRE WEATHER...STRONG WINDS ARE EXPECTED OVER MOST OF SOUTHEAST
WYOMING AND WESTERN NEBRASKA TODAY AND MONDAY AS A STRONG COLD
FRONT PUSHES ACROSS THE REGION. THESE WINDS WILL BECOME MORE
WIDESPREAD ON MONDAY AFTER THE FRONT PUSHES ACROSS THE AREA.
DOWNSLOPE WINDS WILL RESULT IN A DRY BOUNDARY LAYER WITH MINIMUM
HUMIDITIES LOWERING INTO THE 20S BY MONDAY AND TUESDAY AFTERNOON.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...HIGH WIND WARNING UNTIL NOON MONDAY FOR WYZ106-WYZ110-WYZ116-
WYZ117.
WINTER WEATHER ADVISORY FROM NOON SUNDAY TO NOON MONDAY FOR
WYZ112-WYZ114.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...TJT
LONG TERM/AVIATION...CLAYCOMB
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
359 PM EST SUN MAR 3 2013
.SYNOPSIS...
LOW PRESSURE MOVING WEST ONTO NOVA SCOTIA THIS EVENING WILL TURN
SOUTHEAST OUT TO SEA...TO THE SOUTH OF NOVA SCOTIA LATE MONDAY.
LOW PRESSURE OVER KENTUCKY TUESDAY WILL SLOWLY INTENSIFY AS IT
REDEVELOPS OVER SOUTHEAST VIRGINIA OR NORTHEAST NORTH CAROLINA
WEDNESDAY. IT THEREAFTER HEADS SLOWLY EAST OR NORTHEAST OUT TO
SEA ON THURSDAY, WITH HIGH PRESSURE BUILDING INTO THE MID ATLANTIC
STATES FRIDAY AND SATURDAY. A WEAK COLD FRONT MAY CROSS THE REGION
LATE SATURDAY OR SUNDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A 19Z SURFACE ANALYSIS PLACED LOW PRESSURE NEAR NOVA SCOTIA. A
NARROW AREA OF HIGH PRESSURE WAS FROM THE LOWER MISSISSIPPI VALLEY
TO THE WESTERN GREAT LAKES. LOW PRESSURE WAS NEAR THE WESTERN
DAKOTAS. AN UPPER AIR ANALYSIS PLACED A CLOSED LOW NEAR SOUTHERN NEW
ENGLAND, WITH A LARGE TROUGH IN THE EASTERN U.S. A RIDGE WAS ACROSS
THE PLAINS, THEN A STRONG TROUGH WAS JUST INLAND FROM THE PACIFIC
NORTHWEST. A FOCUSED AREA OF 850 MB WAA WAS IN THE CENTRAL AND
SOUTHERN PLAINS. A STRONG 250 MB JET WAS FROM THE MIDWEST TO THE
NORTHEASTERN GULF OF MEXICO THEN OFF THE EAST COAST.
THE PERSISTENT UPPER-LEVEL TROUGH ACROSS THE EASTERN U.S. WILL BE
ENHANCED SOME TONIGHT AS A STRONG SHORT WAVE DIVES SOUTHEASTWARD
DOWN THE WESTERN SIDE. AS THIS FEATURE SLIDES MOSTLY TO OUR SOUTH
LATE TONIGHT, THE CLOSED LOW AND ASSOCIATED SURFACE LOW NEAR NOVA
SCOTIA IS FORECAST TO RETROGRADE SOME. THIS IS ALREADY OCCURRING AS
WATER VAPOR IMAGERY SUGGESTS, WHICH IS A RESULT OF A BLOCKING
PATTERN. PRIOR TO THIS THOUGH, OUR SENSIBLE WEATHER IS DRIVEN BY AN
AIRMASS THAT IS QUITE COLD ESPECIALLY ALOFT WITH 500 MB TEMPERATURES
NEAR -27C. THIS RESULTED IN A WEALTH OF STRATOCUMULUS ACROSS THE
AREA, HOWEVER SOME DRYING HAS BEEN EVIDENT WITH DEW POINTS DROPPING
SOME AND ALSO SOME HOLES OPENING UP ACROSS NEW JERSEY. THE FORECAST
SOUNDINGS SUGGEST THAT WHILE SOME ADDITIONAL THINNING COULD OCCUR
THROUGH TONIGHT, A MORE PRONOUNCED LOW-LEVEL INVERSION LOWERS SOME.
WHILE SOME ADDITIONAL DRYING TENDS TO OCCUR, WHATEVER MOISTURE IS
LEFT WOULD TEND TO GET TRAPPED UNDER THIS. THE NAM IS MORE ROBUST
WITH THIS SCENARIO, HOWEVER GIVEN THE PATTERN WE ARE IN, THE CLOUDS
PROBABLY WILL THIN OUT SOME MORE FOR A TIME. WE TRIED TO LEAN IN
THIS DIRECTION ESPECIALLY THE FARTHER EAST AND SOUTH ONE GOES ACROSS
THE CWA.
THE CYCLONIC FLOW AND LINGERING PVA HAS PRODUCED SOME FLURRIES,
ALTHOUGH THIS APPEARS TO BE MORE FOCUSED ACROSS THE FAR NORTHWEST
ZONES NOW. THEREFORE, WE WILL CONTINUE WITH SOME FLURRIES THERE
THROUGH THE NIGHT. INTERESTINGLY ENOUGH SOME OF THE HIGH RESOLUTION
GUIDANCE, SUCH AS THE HRRR AND SPC WRF, SUGGEST SOME FLURRIES OR A
NARROW STREAMER OR TWO OF SNOW SHOWERS ARRIVES MAINLY DURING THE
COURSE OF THIS EVENING. THESE ARE TOUGH TO FORECAST AND WHILE WE
CANNOT RULE IT OUT GIVEN THE SHORT WAVE ENERGY, WE LEFT IT OUT ATTM
DUE TO LOW CONFIDENCE.
A TIGHTENED PRESSURE GRADIENT REMAINS, HOWEVER IT APPEARS THAT THE
VERTICAL MIXING HAS PEAKED. WE WILL STILL HAVE BRISK CONDITIONS FOR
MOST LOCALES INTO THIS EVENING AS SOME GUSTS REACH TO NEAR 25 MPH.
THIS VERTICAL MIXING LOOKS TO GENERALLY DECOUPLE FOR MANY LOCALES
THIS EVENING BEFORE AN UPTICK MAY OCCUR AGAIN. AS THE AFOREMENTIONED
SHORT WAVE AMPLIFIES THE MAIN TROUGH FOR A TIME TONIGHT, THE
PRESSURE GRADIENT IS FORECAST TO TIGHTEN SOME MORE OVERNIGHT. THE
FORECAST SOUNDINGS SUGGEST THAT THE MIXING STARTS TO INCREASE ONCE
AGAIN LATE TONIGHT, THEREFORE THE SURFACE WINDS MAY START TO
RESPOND. THEREFORE, WE TRIED TO DEPICT THIS IN THE GRIDDED DATABASE.
AS FOR LOW TEMPERATURES, WE GENERALLY USED A MOS BLEND WITH JUST
SOME MINOR ADJUSTMENTS. IT WILL BE A RATHER COLD NIGHT, HOWEVER IF
THE WIND PICKS UP AGAIN /OR HOLDS UP ENOUGH/ THEN THIS MAY KEEP THE
AIR TEMPERATURES A BIT HIGHER.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
A BLOCKING PATTERN IS MAINTAINED WITH A CLOSED LOW TENDING TO DRIFT
SOUTHWESTWARD SOME FROM NOVA SCOTIA. A SIGNIFICANT SHORT WAVE THAT
ROTATES UNDERNEATH THIS MAIN UPPER-LEVEL TROUGH LOOKS TO PULL THE
MAIN PORTION OF THE TROUGH TO OUR EAST BY THE END OF THE DAY. AS
THIS OCCURS, OUR REGION REMAINS WITHIN A CYCLONIC FLOW REGIME WITH
EMBEDDED SHORT WAVES STILL MOVING OVERHEAD WITH THE STRONG
NORTHWESTERLY FLOW. THESE SHORT WAVES ARE FORECAST TO BECOME MORE
CHANNELIZED THROUGH THE DAY.
THE FORECAST SOUNDINGS OVERALL SHOW SOMEWHAT DRIER AIR IN PLACE,
WHICH WOULD SUGGEST LESS IN THE WAY OF CLOUDS. SINCE THE CORE OF THE
UPPER-LEVEL TROUGH IS FORECAST TO BE SHIFTING TO OUR EAST, WE WILL
PROBABLY LOSE SOME OF THE THERMAL DIFFERENTIAL FROM THE SURFACE TO
ALOFT. IF THIS IS THE CASE, THE CLOUDS MAY NOT FILL IN AS MUCH.
GIVEN THE CLOSE PROXIMITY OF THE MAIN UPPER-LEVEL TROUGH AND
CYCLONIC FLOW PRESENT, WE STILL CARRIED A FAIR AMOUNT OF CLOUDS. THE
GREATEST IS ACROSS THE NORTHWEST ZONES GIVEN THE COLD FLOW OFF THE
LAKES. WE ALSO CARRIED FLURRIES IN THE POCONOS WITH THIS NORTHWEST
FLOW AND SOME GUIDANCE SUGGESTING SOME LAKE ONTARIO ACTIVITY MAKES
IT INTO NORTHEAST PENNSYLVANIA. THE 850 MB TEMPERATURES ARE FORECAST
TO MODERATE THROUGH THE DAY, SO THIS MAY ALSO KEEP THE CLOUD COVER A
BIT LESS.
AS THE ENTIRE CLOSED LOW RETROGRADES SOME, THE PRESSURE GRADIENT,
ASSOCIATED WITH THE SURFACE LOW TO OUR NORTHEAST AND THEN HIGH
PRESSURE IN THE OHIO VALLEY, WILL TIGHTEN. THE FORECAST SOUNDINGS
INDICATE STRONGER FLOW ABOVE THE SURFACE AND THE LOW-LEVEL LAPSE
RATES STEEPENING. THIS LEADS TO DEEPER VERTICAL MIXING AS WE GO
THROUGH THE MORNING AND AFTERNOON. AS A RESULT, WE ARE ANTICIPATING
A BREEZY TO WINDY DAY /PEAK GUSTS NEAR 30 MPH/.
AS FOR TEMPERATURES, WE WENT WITH AN EVEN NAM/GFS BLEND. THE AIRMASS
IS STILL CHILLY DESPITE IT STARTING TO MODERATE ALOFT, THEREFORE WE
LEANED A BIT MORE TOWARD THE COOLER GUIDANCE FOR MANY LOCALES.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
**SUBSTANTIAL LONG DURATION NOREASTER FOR AT LEAST THE SOUTHERN
PORTION OF OUR AREA WEDNESDAY INTO THURSDAY**
DEFERRED ON WATCHES AT THIS TIME SINCE WE`RE FORECAST FOR PERIODS
6-8...72 TO 96 HOURS IN ADVANCE.
THOSE WITH CONCERNS FOR S NJ...DE AND E MD SHORE AND FAR SE PA
WEDNESDAY INTO THURSDAY SHOULD MONITOR LATER STATEMENTS...WATCHES
AND POSSIBLE WARNINGS FOR THE FOLLOWING HAZARDS BEGINNING TOMORROW
MORNING:
COASTAL FLOOD...MODERATE OR MAJOR COASTAL FLOOD THREAT FOR THE S
NJ AND ESPECIALLY DELAWARE ATLANTIC COAST. PLEASE SEE TIDE SECTION
FOR MORE DETAILS.
WIND...POTENTIAL HIGH WIND EVENT /60 MPH GUSTS/ FOR COASTAL SOUTHERN
NEW JERSEY AND ESPECIALLY COASTAL DELAWARE WITH WIND ADVISORY
POTENTIAL FOR THE REMAINDER OF SOUTHERN AND CENTRAL DELAWARE...E
MD AND INTERIOR SOUTH THIRD OF NJ POSSIBLY THROUGH PHILADELPHIA
AND SE PA.
SNOW...ESPECIALLY ELEVATIONS. THE BOUNDARY LAYER TEMPERATURE
GOVERNS RAIN/SNOW.
RIGHT NOW THE LOWEST 50 MB ABOVE 0C LAYER IS THE DIFFICULTY ON
CONFIDENTLY FORECASTING A MAJOR WET SNOW. IT IS ANTICIPATED THAT
THERE WILL BE A PERIOD OF HEAVY WET SNOW THAT WILL ACCUMULATE
SEVERAL SLOPPY INCHES IN PARTS OF OUR AREA...ESPECIALLY NORTHERN
DELAWARE AND ADJACENT NE MD AND POSSIBLY SE PA. 06Z-12Z/3 GFS
DENDRITE GROWTH LOOKS TO BE SUBSTANTIAL FOR 12 HOURS WEDNESDAY
OVER E MD AND DE. HOWEVER... ITS FAR TOO EARLY TO BE CONFIDENT ON
AMOUNTS... TIMING AND AREAL COVERAGE. IF THIS RAIN CHANGING TO
HEAVY WET SNOW DOES OCCUR...AND IT LASTS FOR 6 HOURS OR MORE WITH
THE SURFACE TEMP 33F...WE WOULD HAVE A CHANCE FOR POWER OUTAGES
DUE TO WET SNOW ACCRETION ON TREES AND WIRES. AGAIN FAR TOO EARLY.
FOR NOW OUR SNOW GRIDS ARE VERY CONSERVATIVE DUE TO THE SFC TEMPS.
HYDRO...NO CONCERNS EXCEPT FOR PERIODS OF NUISANCE POOR DRAINAGE
FLOODING...PROVIDED THE AXIS OF 1 TO 3 INCHES OF RAIN DOES NOT
CREEP NORTH OF WILMINGTON.
OVERALL PATTERN THIS FORECAST PERIOD: BLOCKING PATTERN IN NORTHEAST
CANADA SLOWLY ERODES BY THE END OF THE WEEK. THE PRIMARY SHORTWAVE
IS ALREADY CLOSING OFF OVER THE DAKOTAS MONDAY EVENING ARRIVING OVER
NORTHEAST NORTH CAROLINA OR SOUTHEAST VIRGINIA WEDNESDAY. IT THEN
HEADS SLOWLY EAST OUT TO SEA AND WEAKENS BY FRIDAY AS RIDGING DEVELOPS
ALONG THE EAST COAST. WEAK TROUGHING REPLACES THE PREVIOUS BLOCK
OVER NORTHEAST CANADA BY SUNDAY WHILE A NEW LARGE SCALE CLOSED LOW
DRIFTS EAST INTO THE SOUTHERN AND CENTRAL PLAINS.
CALENDAR DAY AVERAGE TEMPS: NEAR OR A BIT BELOW NORMAL TUESDAY AND
WEDNESDAY THEN SLOWLY WARMING ABOVE NORMAL SO THAT BY FRIDAY...
SATURDAY AND SUNDAY TEMPS MAY BE AVERAGING ALMOST 5 DEGREES ABOVE
NORMAL.
THE DAILIES BELOW...
STATISTICAL GUIDANCE GOVERNING THIS FORECAST WAS A BLEND OF THE
12Z/3 GFS/NAM MOS THROUGH TUE NIGHT...THEN THE GFS MEX MOS WED
THROUGH THURSDAY WITH SOME COLDER 2M TEMP BLENDING. FOR THURSDAY NIGHT
AND BEYOND...RELIED SOLELY ON 15Z/3 HPC GUIDANCE UNLESS OTHERWISE
NOTED. HAVE NOT SPENT MUCH TIME ADJUSTING THE HPC FORECAST FOR THE
PERIOD THURSDAY NIGHT THROUGH SUNDAY WITH ANY ADJUSTMENTS FOCUSED
IN THE TUE NIGHT-THU AFTERNOON TIME FRAME...ESPECIALLY SINCE THE
12Z ECMWF OP HIGH RES RUN DID NOT ARRIVE IN TIME FOR DIRECT
INCLUSION INTO THE FORECAST.
THE DAILIES BELOW...
MONDAY NIGHT AND TUESDAY...FAIR SEASONABLY COOL WEATHER WITH
DIMINISHING NW WIND GUSTS OF 20-25 MPH MONDAY EVENING BECOMING LIGHT
NORTH OR NORTHEAST TUESDAY AFTERNOON.
TUESDAY NIGHT...INCREASING AND THICKENING CLOUDS. CHANCE OF SNOW OR
PRECIPITATION LATE. CONSERVATIVE FORECAST WITH BLENDED 12Z/3 NCEP
MOS GUIDANCE. WE DID NOTE THE UKMET DROPPING .04 DOWN INTO NE NJ
SEPARATELY FROM THE ONCOMING MID ATLANTIC CLOSED LOW BUT DID NOT
PLAY THIS UP. IN ANY CASE...A COVERING OF SNOW IS POSSIBLE BY
DAYBREAK WEDNESDAY BUT DIDNT PLAY THIS UP DUE TO ONSET OF PCPN
TIMING ISSUE AND PTYPE/SFC TEMP. PLEASE MONITOR LATER FORECASTS.
IT COULD BE A SLIPPERY START TO WEDNESDAY IN SE PA AND NE MD.
WEDNESDAY...STORMY OVER THE SRN PART OF THE AREA. PLAYED THIS
MOSTLY AS RAIN DUE TO THE ABOVE FREEZING BOUNDARY LAYER BUT IT
COULD BE A CLOSE CALL IN PARTS OF MD WESTERN DELAWARE AND SE PA.
LONG WAYS TO GO...SO WE CAN TRY TO IRON OUT EXPECTATIONS AS WE
DRAW CLOSER TO THE EVENT. 12Z/3 NCEP GUIDANCE POPS WERE TRIMMED
IN NE PA AND NNJ RESPECTING THE SOUTHWARD ECMWF/UKMET CAMP. COULD
BE A SHARP CUTOFF ON THE NRN EDGE GOING FROM NO PCPN TO OVER HALF
AN INCH IN 50 MILES. ALSO CONCERNED ABOUT 60 MPH WIND GUSTS IN DE
AND FAR SE NJ.
SO...A MULTI HAZARD DAY. WIND...COASTAL FLOODING...POSSIBLY SNOW
AND POOR DRAINAGE FLOODING...MOSTLY DE/MD/S NJ AND FAR SE PA.
PLEASE NOTE THE FORECAST WORDING IN SOME OF THE ZONES IS LESS THAN
DETERMINISTICALLY IDEAL BUT WHERE ITS COMPLEX...ALSO STATES WHERE
THERE IS GREATER UNCERTAINTY AS TO THE PTYPE.
THURSDAY...SLOW CLEARING FM WEST TO EAST...TIMING OF THIS PROCESS
UNCERTAIN AT THIS TIME. WINDY NORTHERLY FLOW WITH GUSTS 25 TO 35
MPH.
THURSDAY NIGHT-SUNDAY...GENERALLY FAIR WEATHER EXPECTED WITH
GUSTY NORTH NORTHWEST WINDS OF 20 TO 25 MPH THROUGH FRIDAY
BECOMING LIGHT SATURDAY. HPC GUIDANCE FOLLOWED CLOSELY.
&&
.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
REST OF THIS AFTERNOON...VFR CEILINGS, WITH THE MAIN BASES
BETWEEN 4,000 AND 6,000 FEET. THERE IS AN AREA OF SOME DRIER AIR
WORKING SOUTHWARD ACROSS NEW JERSEY AND FAR EASTERN PENNSYLVANIA,
AND THIS SHOULD THIN OUT THE CLOUDS ESPECIALLY AT MANY OF THE
TERMINALS. NORTHWEST WINDS 10-15 KNOTS WITH LOCAL GUSTS TO NEAR 20
KNOTS.
TONIGHT...VFR. THE CEILINGS THINNING OUT SHOULD FILL BACK IN,
ESPECIALLY NORTH AND WEST OF THE KPHL METRO AREA. NORTHWEST
WINDS AROUND 10 KNOTS, HOWEVER SOME GUSTS MAY OCCUR AGAIN ESPECIALLY
LATE.
MONDAY...VFR. NORTHWEST WINDS 15-20 WITH GUSTS TO AROUND 25 KNOTS.
OUTLOOK...
MON NIGHT...VFR EXCEPT POSSIBLE MVFR CIGS VCNTY KMPO CLEARING LATE.
NW WIND GUST 15-25 KTS TO BEGIN THE EVENING...THEN DIMINISHING.
HIGH CONFIDENCE.
TUESDAY...VFR. LIGHT NORTH WIND BECOMING NORTHEAST. HIGH CONFIDENCE.
TUESDAY NIGHT...CONDS MAY LOWER TO MVFR IF PRECIPITATION DEVELOPS
LATE. INCREASING NE WIND LATE. BELOW AVERAGE CONFIDENCE ON DETAILS.
WED...MVFR OR IFR CONDS IN RAIN OCCASIONALLY CHANGING TO SNOW...ESPECIALLY
KPHL SOUTH. NE WIND SHOULD GENERALLY GUST 25-35 KTS DURING THE DAY
AND EVENING WITH HIGHER GUSTS TO 45 KNOTS ALONG THE COAST. AVERAGE
CONFIDENCE.
THU...ANY SUB VFR CONDITIONS EARLY...IMPROVING TO VFR. NNW WIND G
25-35 KTS DURING THE DAY. AVERAGE CONFIDENCE.
FRI...VFR. NNW WIND G20-25 KTS DURING THE DAY. HIGH CONFIDENCE.
&&
.MARINE...
A TIGHT ENOUGH PRESSURE COMBINED WITH A COLD AIRMASS IS MAINTAINING
ENOUGH VERTICAL MIXING. THE NORTHWEST FLOW IS ALIGNED ENOUGH TO
FUNNEL DOWN THE LENGTH OF DELAWARE BAY. THIS HAS RESULTED IN GUSTS
TO AROUND 25 KNOTS ESPECIALLY AROUND THE BAY MOUTH. THE FORECAST
SOUNDINGS INDICATE THAT THE FLOW INCREASES SOME THROUGH THE NIGHT,
WITH THE LOW-LEVEL LAPSE RATES STEEPENING. AS THIS OCCURS, THE
MIXING SHOULD DEEPEN A BIT MORE ACROSS ALL OF OUR WATERS. AS A
RESULT, THE SMALL CRAFT ADVISORY IS IN EFFECT THROUGH TONIGHT. THE
STRONG NORTHWEST FLOW AND CHILLY AIRMASS IS EXPECTED TO MAINTAIN
DEEPER MIXING MONDAY AS WELL, THUS THE PREVIOUSLY ISSUED ADVISORY
REMAINS IN EFFECT THROUGH THE DAY MONDAY. SEAS 2-4 FEET SHOULD
INCREASE A LITTLE MORE DUE TO THE UPTICK IN THE WINDS, HOWEVER GIVEN
THE OFFSHORE FLOW, THE HIGHEST SEAS SHOULD BE FARTHER OFFSHORE AND
IN LOWER DELAWARE BAY AND THROUGH THE BAY MOUTH.
OUTLOOK...
SCA WAS EXTENDED TIL ABOUT MIDNIGHT MONDAY NIGHT FOR LEFTOVER NW
FLOW GUSTS TO 25 OR 30 KT. SOME OF THE GUIDANCE SUGGESTS SCT 35 KT
GUSTS NJ AND DE BAY ENTRANCE MONDAY EVENING.
TUESDAY...NO HEADLINE ANTICIPATED AS WINDS DIMINISH AND BECOMING
LIGHT NORTH. NE WINDS INCREASE LATE TUE NIGHT.
WEDNESDAY INTO THURSDAY...AT A MINIMUM A GALE WARNING. A GOOD CHANCE
WE`LL NEED A STORM WARNING...ESPECIALLY VCNTY CAPE MAY SOUTHWARD.
SEAS TO AT LEAST 15 FEET OFF THE SNJ AND DE COAST WITH POSSIBLE 20
FT AT THE 44009 BUOY.
PRIMARY THREAT FOR STRONGEST WIND APPEARS TO BE CENTERED WEDNESDAY
EVENING WITHIN SEVERAL HOURS OF 7 PM.
FRIDAY...ATLC WATERS AN SCA FOR LEFTOVER NE SWELL OF 5 TO 8 FEET AND
13 SECONDS. DE WATERS MIGHT NEED AN SCA FOR WIND GUSTS.
&&
.TIDES/COASTAL FLOODING...
EXPECTING A WATCH WILL BE NEEDED FOR MULTIPLE TIDE CYCLES ALONG
THE ATLC COAST WED AFTERNOON AND THURSDAY MORNING HIGH TIDES...
ESPECIALLY ATLANTIC CITY SOUTH. EVEN THE TIDAL DELAWARE WILL
PROBABLY NEED AN ADVISORY FOR THE WED EVENING AND THURSDAY
DAYBREAK HIGH TIDE CYCLES.
SURGE OF NEARLY 4 FEET IS EXPECTED WITH THE PRIMARY DANGER PERIOD
THE EARLY THURSDAY MORNING HIGH TIDE CYCLE ALONG THE ATLANTIC
COAST...ESPECIALLY DELAWARE. SEAS OF 15 FEET ARE PROBABLY POUNDING
THE DELAWARE COAST WITH WIND GUSTS TO AT LEAST 50 MPH WEDNESDAY
NIGHT. HOWEVER...SINCE THE MODELS ARE TRENDING A BIT FASTER... ITS
YET POSSIBLE THE THE WEDNESDAY AFTERNOON STORM TIDE WILL EQUAL THAT
OF THURSDAY MORNING.
SURGE AT LOW AND HIGH TIDE WEDNESDAY NIGHT ON THE ATLANTIC WATERS
NEAR OR AROUND 4 FEET...WHICH COMBINED WITH POSSIBLE HEAVY
RAINFALL...COULD MEAN TIDAL INUNDATION FLOODING OF ABOUT 3 HOURS
EITHER SIDE OF THE THE HIGH TIDE.
A SURGE OF 3.6 FEET WEDNESDAY AFTERNOON AND 2.5 FEET THURSDAY
MORNING WOULD REACH THE THRESHOLD OF MDT COASTAL FLOODING WHICH
SEEMS ALMOST A CERTAINTY IN DELAWARE. ADD A FOOT FOR MAJOR WHICH IS
A LOWER RISK BUT QUITE POSSIBLE AND ALREADY MODELED BY A RATHER
STRONG 12Z GFS CYCLE. IF FUTURE MODEL RUNS ARE WEAKER...THEN THE
SURGE AND CONSEQUENT POTENTIAL FOR A MAJOR COASTAL FLOOD EVENT
WOULD BE LESS.
ALL OF THIS IS IMPORTANT...PARTLY BECAUSE OF OF THE DAMAGE
INCURRED WITH SANDY THIS PAST OCTOBER BUT ALSO SINCE SOME OF MODEL
GUIDANCE IS OUTLOOKING ABOUT THE 3RD OR 4TH HIGHEST STORM TIDE ON
RECORD FOR LEWES. THAT VALUE IS NOT A DONE DEAL BUT ITS IN THE MIX
OF POSSIBILITIES.
HERE ARE THE TIMES OF HIGH TIDE AND THE FORECAST ASTRONOMICAL TIDE
HEIGHTS FOR SELECTED POINTS ALONG THE COAST. THE FORECAST
ASTRONOMICAL TIDE HEIGHT PLUS THE ACTUAL STORM SURGE WILL EQUAL THE
ACTUAL WATER LEVEL AT THE TIME OF HIGH TIDE.
ALL HEIGHTS ARE IN MEAN LOWER LOW WATER (MLLW).
WEDNESDAY THURSDAY
REHOBOTH BEACH DE 3.2 FT AT 250 PM 4.2 FT AT 335 AM
LEWES DE 3.6 FT AT 355 PM 4.6 FT AT 434 AM
CAPE MAY NJ (OCEANFRONT) 3.8 FT AT 319 PM 5.0 FT AT 354 AM
ATLANTIC CITY NJ 3.4 FT AT 245 PM 4.5 FT AT 320 AM
SEASIDE HEIGHTS NJ (OCEANFRONT) 4.0 FT AT 228 PM 4.7 FT AT 301 AM
SANDY HOOK NJ 4.3 FT AT 258 PM 5.1 FT AT 331 AM
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST TUESDAY FOR ANZ450>455.
SMALL CRAFT ADVISORY UNTIL 1 AM EST TUESDAY FOR ANZ430-431.
&&
$$
SYNOPSIS...DRAG 357
NEAR TERM...GORSE 357
SHORT TERM...GORSE 357
LONG TERM...DRAG 357
AVIATION...DRAG/GORSE 357
MARINE...DRAG/GORSE 357
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
351 PM EST SUN MAR 3 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 350 PM EST SUN MAR 3 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A VIGOROUS SHORTWAVE TROUGH
OVER NRN MONTANA...A MID/UPPER LEVEL RIDGE OVER THE PLAINS AND NE
CANADA AND TROUGHING OVER NRN MANTIOBA AND THE SE CONUS LEAVING A
COL OVER THE NRN GREAT LAKES. AT THE SFC...A RIDGE EXTENDED FROM NW
ONTARIO THROUGH WRN UPPER MI INTO WI AND IL. SIMILAR TO
YESTERDAY...LES AND CLOUDS HAVE DIMINISHED DURING THE AFTERNOON AS
DAYTIME MIXING AND VERY DRY AIS UPSTREAM HELPS ERODE THE
CLOUD BANDS.
TONIGHT AND MON...ALSO SIMILAR TO PREVIOUS FEW NIGHTS...EXPECT SOME LES
TO REDEVLOP OVERNIGHT AS UPSTREAM MIXING/DRYING SUBSIDES AND LAND
BREEZES DEVELOP. HOWEVER...HIGH RES MODELS SUGGEST THAT LOW LEVEL
CONV WILL BE WEAKER THAN LAST NIGHT WITH MAINLY DIFLUENT ACYC FLOW
OVER THE THE WEST HALF OF LAKE SUPERIOR. WEAK UPSLOPE FLOW INTO N
CNTRL UPPER MI SHOULD HELP PRODUCE AT LEAST SOME FLURRIES EVEN WITH
INVERSION HEIGHTS AT OR BELOW 2K-3K FT. WITH LOW CONFIDENCE IN EVEN
ANY LIGHT MEASURABLE LES...FCST RETAINED PREV MENTION OF SLIGHT
CHANCE POPS. FAVORABLE RADIATIONAL COOLING CONDITIONS INLAND SHOULD
WILL ALLOW TEMPS TO DROP TO LOWER END OF GUIDANCE WITH READINGS IN
THE 0 TO 10 BELOW ZERO RANGE.
AS ACYC WINDS BACK TO THE ENE...EXPECT REMAINING LES/FLURRIES TO END
BY MIDDAY MON. TEMPS SHOULD REBOUND TO READINGS CLOSER TO SEASONAL
AVERAGES NEAR 30...PER FCST SOUNDINGS LOW LEVEL TEMP PROFILE.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 350 PM EST SUN MAR 3 2013
FOCUS INITIALY IS ON SHORTWAVE TROUGH DIGGING SOUTHEAST ACROSS
NORTHERN PLAINS. CONVERGENCE AND MOISTURE ADVECTION ALONG AND
NORTH OF SFC/H85/H7 LOWS AND DIVERGENCE ALOFT FROM H25 JET STREAK
SHOULD BE SUPPORTING SWATH OF MODERATE TO HEAVY SNOW FROM EASTERN
NORTH DAKOTA THROUGH MOST OF MINNESOTA AND INTO SOUTHERN WISCONSIN.
H85-H7 FRONTOGENESIS AND H85 MOISTURE STAY FAR ENOUGH TO SOUTH TO
KEEP NORTHERN EDGE OF SNOW SHIELD OUT OF CWA MONDAY NIGHT. H7-H6
FRONTOGENESIS AND INCREASING 1000-700MB MOISTURE PROBABLY WILL ALLOW
SYSTEM SNOW TO CLIP FAR WEST TUESDAY. KIWD WOULD SEE BEST CHANCE OF
SEEING THIS SYSTEM SNOW. FARTHER NORTH...EXPECT INCREASING LIGHT
SNOW MAINLY DUE TO WINDS BECOMING MORE NORTHEAST AND WITH INCREASING
925-850MB MOISTURE. THE ADDITIONAL MOISTURE ALONG WITH FLOW OFF LK
SUPERIOR AND MINOR COOLING AT TOP OF INVERSION TO AROUND -12C WILL
BE SUFFICIENT TO RESULT IN LAKE ENHANCED SNOW. GIVEN THE PERSISTENT
LIGHT LK EFFECT SEEN OFF AND ON OVER NCNTRL UPR MICHIGAN SINCE
THURSDAY WITH QUITE MARGINAL CONDITIONS IN TERMS OF INVERSION
HEIGHT/TEMPS...PRETTY CONFIDENT SNOW WILL OCCUR TUESDAY/TUESDAY
NIGHT/WEDNESDAY MORNING. TOTAL SNOW ACCUMULATIONS WILL BE LIMITED
GIVEN ABSENCE OF LARGER SCALE FORCING AND WITH MAJORITY OF LIFT
OCCURRING AT TEMPS WARMER THAN -10C LEADING TO SLR/S LESS THAN 10:1.
EVEN SO...SOME HIGHER TERRAIN AREAS OVER FAR WESTERN UPR MICHIGAN
AND IN NCNTRL UPR MICHIGAN MAY END UP WITH A FEW INCHES OF SNOW BY
LATER WEDNESDAY.
H925 TEMPS AROUND -10C WITH WEAK NORTHERLY WINDS AND SUFFICIENT
MOISTURE BLO INVERSION WILL RESULT IN LIGHT LK EFFECT PERSISTING
THROUGH LATE WEDNESDAY. SINCE SFC-H925MB WINDS DO NOT BECOME MORE
SOUTHERLY UNTIL THURSDAY MORNING...LIGHT LK EFFECT/FLURRIES PROBABLY
WILL LINGER ALONG PORTIONS OF LK SUPERIOR SHORE WEDNESDAY NIGHT. BY
TIME WINDS DO BECOME MORE SOUTHERLY...TEMPS ARE FURTHER WARMING...SO
DO NOT EXPECT ANY LK EFFECT OFF LK MICHIGAN. COULD BE ENHANCEMENT TO
CLOUDS THOUGH WHICH WOULD TEMPER WARMING ON THURSDAY FOR THE EAST.
H5 RIDGE BUILDS FROM CNTRL CONUS ACROSS GREAT LAKES THURSDAY INTO
FRIDAY. BY LATER FRIDAY...TROUGH OVER WESTERN CONUS SPLITS LEAVING
SEPARATE SOUTHERN STREAM TROUGH OVER SOUTHWEST CONUS AND NORTHERN
STREAM TROUGH PUSHING ACROSS SCNTRL CANADA. SFC-H85 TROUGHING FORMS
IN RESPONSE OVER THE NORTEHRN PLAINS WHICH INCREASES SOUTHERLY
WINDS OVER UPR LAKES THURSDAY NIGHT INTO FRIDAY. WINDS MAY BECOME
BREEZY WITH GUSTS OVER 20 MPH...BUT LACK OF STRONGER PRESSURE
GRADIENT WILL KEEP REAL STRONG WINDS FROM OCCURRING.
GFS INDICATES STRONGER NORTHERN STREAM DYNAMICS HEAD EAST QUICKLY ON
FRIDAY WHILE OUTRUNNING THE SFC TROUGH...SO THE TROUGH REALLY LOSES
ITS PUNCH AS IT MOVES ACROSS THE AREA. ECMWF FAIRLY SIMILAR WITH
OVERALL IDEA. SHOULD NOTE THAT THE GEM-NH A BIT STRONGER/FARTHER
SOUTH WITH NORTHERN STREAM WAVE SO IT GENERATES MORE QPF IN WARM AIR
ADVECTION AHEAD OF THE WAVE ON FRIDAY. GFS TRYING TO GENERATE SOME
LGT DRIZZLE LIKE PRECIP ON FRIDAY WITH LOW-LEVEL MOISTURE BENEATH
DRIER AIR IN MID LEVELS. THINK THAT LACK OF DEEPER MOISTURE INTO THE
SYSTEM SUGGESTS THAT NOT MUCH PRECIPITATION WILL OCCUR ON FRIDAY.
WILL NOT ALTER SLIGHT CHANCE POPS FROM CONSENSUS OF MODELS. SOME
INDICATION THAT AS WARMING KICKS IN ABOVE H9 AHEAD OF THE
TROUGH...LOW-LEVEL MOISTURE MAY REMAIN TRAPPED BENEATH THE INVERSION
OVER MUCH OF CWA RIGHT THROUGH FRIDAY. MAIN IMPACT WILL BE ON TEMPS
THURSDAY THROUGH FRIDAY. DUE TO STRICT TEMPERATURE ADVECTION WOULD
THINK MANY AREAS THURSDAY AND FRIDAY WILL STILL BE ABLE TO CRACK THE
FREEZING MARK.
MODELS NOT AS COLD IN WAKE OF FRONT NEXT WEEKEND AS THEY HAVE SHOWED
LAST COUPLE DAYS. ULTIMATELY MAY END UP BEING DRY NEXT WEEKEND /JUST
HAVE SLIGHT CHANCES IN THERE/ WITH TEMPERATURES SIMILAR TO LATE THIS
WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1251 PM EST SUN MAR 3 2013
EXPECT INCREASED DAYTIME MIXING AND DRY ADVECTION TO AGAIN RESULT IN
CLEARING AT SAW...WITH VFR CONDITIONS BY MID TO LATE AFTERNOON.
OTHERWISE...VFR CONDITIONS WILL PREAVIL THROUGH THE FCST PERIOD WITH
A SURFACE RIDGE DOMINATING THE WEATHER IN THE NORTHERN GREAT LAKES.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 350 PM EST SUN MAR 3 2013
STRONGEST WINDS THIS WEEK OCCUR MONDAY AFTERNOON THROUGH TUESDAY
OVER FAR WESTERN LAKE SUPERIOR AS LOW PRESSURE SYSTEM MOVES BY JUST
TO THE SOUTH. EAST-NORTHEAST WINDS TO 30 KTS GOOD BET. MAY BE GALE
GUSTS TOWARD THE HEAD OF LK SUPERIOR AND ALONG THE MINNESOTA SHORE
MONDAY NIGHT INTO TUESDAY MORNING DUE TO COASTAL CONVERGENCE. NORTH
WINDS TO 25 KTS CONTINUE THROUGH TUESDAY NIGHT. DUE TO THE GUSTY
WINDS AND COLDER TEMPERATURES...FREEZING SPRAY WILL BE AROUND AT
TIMES THROUGH WEDNESDAY MORNING. WINDS DIMINISH TO LESS THAN 20 KTS
LATER WEDNESDAY AND THURSDAY AS HIGH PRESSURE CROSSES THE REGION.
SOUTH WINDS TO 25 KTS POSSIBLE THURSDAY NIGHT INTO FRIDAY OUT AHEAD
OF LOW PRESSURE TROUGH. TROUGH MOVES THROUGH FRIDAY NIGHT BUT
WEST-NORTHWEST WINDS IN WAKE OF TROUGH SHOULD STAY BLO 20 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...JLB
MARINE...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1252 PM EST SUN MAR 3 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 511 AM EST SUN MAR 3 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OVER THE WRN CONUS AND
AND TROUGHING OVER THE EAST...RESULTING IN NW MID/UPPER LEVEL FLOW
FROM WRN CANADA THROUGH THE PLAINS INTO THE LOWER MS VALLEY. AT THE
SFC...A RIDGE EXTENDED FROM HUDSON BAY AND NW ONTARIO THROUGH WRN
LAKE SUPERIOR. IN PAST FEW HOURS...COMBINATION OF SUBTLE TROUGHING
AND LOW-LVL CONVERGENCE OVER ERN LAKE SUPERIOR ALONG WITH THE INFLUX
OF SLIGHTLY MORE MOIST AIR AT LOW-LVLS FROM NE OF LAKE SUPERIOR AND
WEAK Q-VECT CONV HAS LEAD TO THE FORMATION OF LAKE CLOUDS AND LIGHT
-SHSN/FLURRIES FROM MARQUETTE EASTWARD AS NOTED ON IR SATELLITE AND
MQT RADAR LOOPS. CLEAR SKIES AND LIGHT WINDS UNDER SFC RDG AXIS HAVE
ALLOWED TEMPS TO DROP WELL BLO ZERO AT MANY LOCATIONS EARLY THIS
MORNING. LOWEST READINGS THUS FAR HAVE BEEN -9F AT KIWD...-4F AT
KCMX AND -2F AT NWS MQT. LAND O LAKES JUST SOUTH OF WATERSMEET HAS
PLUMMETED TO -13F.
TODAY...SIMILAR TO YESTERDAY...EXPECT CLOUDS AND ASSOC LES TO
GENERALLY DISSIPATE BY LATE MORNING/EARLY AFTERNOON AS LOW-LVL
CONVERGENCE WEAKENS AND Q-VECT DIVERGENCE SPREADS IN FROM THE WEST
WITH ADVANCING MID-LVL RDG. EXPECT MAX TEMPERATURES AGAIN SIMILAR TO
YESTERDAY WITH HIGHS RANGING FROM THE LOWER 20S NORTH CENTRAL AND
EAST TO THE MID TO UPPER 20S ELSEWHERE.
NOT AS CONFIDENT ON DEVELOPMENT OF LAKE EFFECT CLOUDS TONIGHT AS
MODEL FCST SNDGS SHOW SUBSIDENCE INVERSION CRASHING TOWARD SFC WITH
STRONG AMPLIFIED RDG MOVING OVER THE AREA. THIS IS ALSO WELL
DEPICTED ON SNDGS WITH STRONG MID-LVL DRYING AND Q-VECT DIV. LOW-LVL
WINDS ARE ALSO GENERALLY MORE DIFLUENT...ALTHOUGH THERE IS STILL
SOME SUBTLE TROFFING AND WEAKLY CONVERGENT NNE FLOW FROM EASTERN
LAKE SUPERIOR INTO NCNTRL COUNTIES...ESPECIALLY ERN MQT AND WRN
ALGER. HAVE TRIMMED BACK POPS SOME FROM PREV FCST DUE TO
AFOREMENTIONED NEGATIVE FACTORS FOR LES...BUT WILL KEEP SOME SLIGHT
CHC POPS OVER ERN MQT/WRN ALGER IN CASE SOME LIGHT LES/FLURRIES CAN
BE INITIATED THERE DUE TO WEAK LOW-LVL CONVERGENCE. EXPECT SOME
SUB-ZERO LOW TEMPS AGAIN OVER THE FAR WRN INTERIOR UNDER CLEAR SKIES
AND LIGHT WINDS OF SFC RDG AXIS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 511 AM EST SUN MAR 3 2013
SOME LIGHT LINGERING LES WILL CONTINUE ON MON IN NE LOW LEVEL FLOW
AS SFC AND UPPER LEVEL RIDGING MOVES IN. GIVEN MARGINAL TEMPS FOR
LES AND OVERALL CONDITIONS THAT WILL BE DETRIMENTAL TO LES...ONLY
SLIGHT CHANCE POPS WILL BE MAINTAINED ON MON.
CONDITIONS BECOME MORE FAVORABLE FOR LES TUE INTO WED AS AN UPPER
TROUGH MOVES OVER THE REGION...BRINGING COLDER INVERSION TEMP TEMPS
AROUND -13C AT 900MB...BETTER MOISTURE AND CYCLONIC FLOW. LOW LEVEL
WINDS WILL CONTINUE TO BE OUT OF THE NE-N...SO THE MOST FAVORED
AREAS WILL BE OVER THE HIGHER TERRAIN OF N CENTRAL UPPER MI. COULD
SEE A FEW INCHES OF ACCUMULATION...BUT NOT EXPECTED TOO LARGE OF
AMOUNTS GIVEN MORE MARGINAL INVERSION TOP TEMPS.
THERE ARE TIMING DIFFERENCES BETWEEN MODELS...BUT THEY DO AGREE ON
THE GENERAL IDEA OF BRINGING A SFC HIGH FOLLOWED BY UPPER RIDGING ON
OR AROUND THU. A SERIES OF SHORTWAVE TROUGHS ARE FORECAST TO MOVE
NEARBY FRI AND SAT...BUT NOT SIGNIFICANT PRECIP IS EXPECTED AT THIS
TIME AND CONFIDENCE IS LOWER GIVEN LIMITATION OF NWP WITH THESE
FEATURES THAT FAR OUT.
TAKING A QUICK LOOK AT SFC TEMPS THROUGH THE LONG TERM /SINCE THERE
IS LITTLE ELSE TO TALK ABOUT/...HIGHS MON ARE FORECAST TO BY AROUND
30...AND SHOULD THEN DROP A FEW DEGREES FOR TUE BEFORE SIMILAR TEMPS
COME BACK ON WED. THU SHOULD SEE HIGHS AOA FREEZING IN MOST
LOCATIONS...WITH EVEN WARMER HIGHS IN THE MID TO UPPER 30S ON FRI
AND SAT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1251 PM EST SUN MAR 3 2013
EXPECT INCREASED DAYTIME MIXING AND DRY ADVECTION TO AGAIN RESULT IN
CLEARING AT SAW...WITH VFR CONDITIONS BY MID TO LATE AFTERNOON.
OTHERWISE...VFR CONDITIONS WILL PREAVIL THROUGH THE FCST PERIOD WITH
A SURFACE RIDGE DOMINATING THE WEATHER IN THE NORTHERN GREAT LAKES.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 511 AM EST SUN MAR 3 2013
WINDS LESS THAN 20 KTS THROUGH MONDAY...THEN EXPECT NORTHEAST WINDS
TO INCREASE TO 30 KTS OVER WEST AND NORTH CENTRAL SECTIONS BY MONDAY
NIGHT AS LOW PRESSURE SYSTEM MOVES BY TO THE SOUTH OVER THE NORTHERN
MISSISSIPPI RIVER VALLEY. WINDS 20-30 KTS CONTINUE OVER MOST OF LK
SUPERIOR THROUGH TUESDAY BEFORE SETTLING DOWN TO LESS 20 KTS BY
WEDNESDAY. WEAK PRES GRADIENT OVER AREA WILL MAINTAIN FAIRLY LIGHT
WINDS OF 20 KT OR LESS THROUGH THE REST OF THE WEEK.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...JLB
MARINE...VOSS
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1037 AM CST SUN MAR 3 2013
.DISCUSSION...
16 UTC WATER VAPOR LOOP SHOWS A STRONG UPPER LOW MOVING ALONG THE
NORTHWEST MT/CANADIAN BORDER WHILE ITS SURFACE LOW IS TAKING SHAPE
IN THE LEE OF THE NORTHERN ROCKIES. REGIONAL RADARS SHOW A BAND OF
WEAK ECHOES FROM BRANDON MB TO VALLEY CITY WITH SOME EMBEDDED
HIGHER REFLECTIVITY AROUND 20 DB. SURFACE OBSERVATIONS BENEATH THE
STRONGEST ECHOES NOT REPORTING SNOW...BUT DEVILS LAKE WEBCAMS DO
SHOW SOME FLURRY ACTIVITY. THINK THIS AREA IS IN RESPONSE TO THE
LEADING EDGE OF MID-LEVEL MOISTURE AND SOME WEAK ISENTROPIC LIFT.
ADDED A NARROW BAND OF 20 POPS WEST OF A LINE FROM LANGDON TO
VALLEY CITY FOR A STRAY TENTH OF ACCUMULATION. OTHERWISE...INCLUDED
FLURRY MENTION ALONG AND WEST OF THE VALLEY THROUGH THE EARLY
AFTERNOON. WILL ALSO MENTION PATCHY FOG THROUGH THE REST OF THE
MORNING ACROSS THE DEVILS LAKE BASIN WITH REDUCTIONS IN VISIBILITY
DOWN TO 1 SM.
QUITE THE GRADIENT IN MOISTURE ACROSS THE NORTHERN PLAINS TODAY
COMPARING THE 12 UTC BIS/INL RABOS. SURFACE DEW POINT TEMPERATURES
RANGE FROM THE UPPER 20S TO LOWER 30S ACROSS THE CENTRAL DAKOTAS
TO THE SINGLE DIGITS ABOVE/BELOW ZERO ACROSS THE MN ARROWHEAD. IT
WILL TAKE SOME TIME FOR THE LOW-MID LEVELS TO SATURATE AND THIS IS
REFLECTED IN LATEST RAP/SREF MODEL RUNS WHICH SHOW MAJORITY OF
SNOW HOLDING OFF UNTIL AFTER 21 TO 00 UTC LATE THIS AFTERNOON AND
EVENING. WILL MAKE MINIMAL POP/WX CHANGES AT THIS TIME WITH MOST
SNOW MOVING INTO EASTERN ND AFTER 00 UTC AND PERHAPS NOT INTO THE
VALLEY UNTIL THE MIDNIGHT HOUR OR LATER. WILL NEED TO MAKE A
DECISION ON THE REMAINING WINTER STORM WATCH THIS AFTERNOON...BUT
FOR NOW WILL WAIT FOR THE FULL SUITE OF 12 UTC GUIDANCE AND NOT
MAKE ANY HEADLINE CHANGES.
&&
.AVIATION...
LIFR/IFR CONDITIONS AFFECTING KDVL TRANSITION TO MVFR OVER KGFK...
AND VFR FOR THE REMAINDER OF THE TAF SITES. RAP GUIDANCE SUGGESTS
NOT MUCH CHANGE WITH THESE CONDITIONS THROUGH THE REMAINDER OF THE
DAY...EXCEPT SLIGHTLY IMPROVING CONDITIONS. LATER TONIGHT...EXPECT
LOWERING CONDITIONS WITH THE APPROACH OF THE WINTER STORM.
&&
.PREV DISCUSSION... /ISSUED 332 AM CST SUN MAR 3 2013/
SHORT TERM...
FOR THIS UPCOMING STORM SYSTEM 00Z GFS CAME IN WITH A MORE NRN
SOLN MORE SIMILAR TO ECMWF/NAM AND 00Z GEM CAME WITH A MORE
SIMILAR SOLN AS WELL. THUS CONFIDENCE IN HEAVIEST SNOW AREA IS
HIGHER. 500 MB WAVE MOVING THRU SRN-CNTRL BRITISH COLUMBIA ATTM
WITH QUITE COLD AIR ALOFT WITH SYSTEM AS NOTED BY LIGHTENING
STRIKES IN SOUTHERN B.C. ALSO GOOD MOISTURE PLUME AHD OF UPPER LOW
FROM OFF THE SRN CALIFORNIA COAST INTO MONTANA. MODELS LESS
DISAGREEMENT TONIGHT WITH GENERAL IDEA IS TAKING UPPER LOW TOWARD
GLACIER PARK 00Z MON THEN INTO EITHER SOUTH CENTRAL ND OR CENTRAL
SD BY 00Z TUES. 00Z ECMWF IS CLOSER TO 00Z NAM IN BEING FARTHER
NORTH WHILE 00Z GFS/GEM IS STILL A BIT FARTHER SOUTH. SFC LOW
TRACK WOULD HAVE IT FROM NCNTRL MT INTO SOUTHWEST ND THEN INTO
NORTH CENTRAL SD BY 00Z TUE THEN TOWARD SIOUX FALLS BY 06Z TUES.
GFS/ECMWF HAS VERY STRONG UPPER LEVEL SUPPORT WITH THIS SYSTEM
WITH GOOD JET DYNAMICS AND STRONG 500-300 MB DIV Q AND QUITE
STRONG 850-700 QG FORCING OVER MOST OF ND INTO MN WITH THIS
FEATURE. USING ISENTROPIC 285K SURFACE SHOWS A GOOD 24 HR PERIOD
OF 3-3.5 G/KG MOISTURE AND LIFT INTO ERN ND AND WRN MN WITH THIS
SYSTEM. MODEL QPF FCSTS SHOWS PERHAPS THE HIGHEST QPF MOVING INTO
PARTS OF CNTRL-SE ND 00Z-06Z MON PERIOD THEN LIFTING NORTH INTO
THE NRN VALLEY 06Z-18Z MON PERIOD. ALL MODELS SHOW A WIDESPREAD 8
TO 12 INCH AMOUNT OF SNOW OVER ALL OF NRN INTO ERN ND INTO NW-
WCNTRL MN WITH ISENTROPIC LIFT CHARTS INDICATING BEST CHC OF FOOT
AMOUNTS OR A TAD MORE ECNTRL ND INTO DVL BASIN.
BASED ON HIGHER CONFIDENCE OF EVENT WILL GO WITH WINTER STORM
WARNINGS FOR 00Z MON-12Z TUE FOR ALL OF ERN ND INTO FAR WRN MN
(HCO-FSE-DTL-ADC WEST). WILL KEEP OR EXPAND WINTER STORM WATCHES A
BIT INTO PARK RAPIDS-BEMIDJI-ROSEAU AREAS AS MANY MODELS SHOW THEM
GETTING 6-8. START TIME OF SNOW THERE PAST 06Z MON SO HAVE TIME TO
UPGRADE IF NEED BE. COORD WITH WFO DLH.
WIND WITH SYSTEM WILL NOT BE A HUGE ISSUE...WILL HAVE A SOUTHEAST
OR EAST WIND 10 TO 20 KTS AHD OF SYSTEM THEN TURN NORTH TUESDAY.
COULD BE SOME GUSTS HIGHER. RATE OF SNOWFALL THOUGH AT TIMES LATER
TONIGHT INTO MONDAY MORNING COULD BE QUITE HVY SO CONTINUED
MENTION OF +SN IN GRIDDS IN MUCH OF ERN ND.
SYSTEM WILL EXIT TUESDAY MORNING.
LONG TERM...WEDNESDAY THROUGH SATURDAY
IN WAKE OF DEPARTING STORM CWFA UNDER HIGH PRESSURE SURFACE AND
ALOFT AT THE START OF THE LONG TERM. LIGHT SFC WINDS EARLY EXPECTED
TO BEGIN INCREASING AS NEXT SYSTEM FORECAST TO BE DEVELOPING IN
WYOMING OR MONTANA. CURRENT MODEL SUITE SHOWS THE TRANSITION TO
SOUTHWEST FLOW ALOFT COMPLETE BY THURSDAY.
MODELS HAVE CONTINUED TO VACILLATE BETWEEN SPLIT FLOW AND MORE
CONSOLIDATED FLOW. 18Z DGEX/00Z GFS SEEMS A BIT BULLISH WITH
STRENGTH OF LEAD SHORTWAVE. ALLBLENDS SHOW LOW POPS FOR THURSDAY
WITH GEM-HEMI SUPPORTING THIS. ECMWF NOT SO DISSIMILAR BUT HAS
PRECIP NORTH OF BORDER. DIFFERENCES ON FRIDAY ARISE AS GFS AND
GEMI-HEMI HAVE SHORTWAVE ENERGY AND LIGHT QPF LINGERING OVER
NORTHEAST FA FRIDAY. ECMWF HAS A SMATTERING OF LOW END QPF AS
WELL...SO CONSENSUS SUPPORTS THIS.
SURFACE HIGH PRESSURE BUILDS IN WITH DRYING COLUMN FOR THE END OF
THIS PERIOD.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM CST TUESDAY
FOR NDZ006>008-014>016-024-026>030-038-039-049-052>054.
MN...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM CST TUESDAY
FOR MNZ001>004-007-013>015-022-027>031-040.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE MONDAY NIGHT
FOR MNZ005-008-009-016-017-023-024-032.
&&
$$
ROGERS/TG/RIDDLE
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
355 PM EST SUN MAR 3 2013
.SYNOPSIS...
A SLOW MOVING UPPER LOW OVER THE NORTHEASTERN STATES WILL EXIT OFF
THE NEW ENGLAND COAST BY LATE MONDAY ALLOWING WEAK HIGH PRESSURE
TO BUILD ACROSS THE LOCAL AREA. LOW PRESSURE WILL DEVELOP IN THE
HIGH PLAINS SUNDAY AND MONDAY AND TAKE A TRACK THROUGH THE OHIO
VALLEY AND MID-ATLANTIC STATES TUESDAY NIGHT AND WEDNESDAY. THIS
STORM WILL PROBABLY PASS TO THE SOUTH OF THE STATE...BUT WILL MOST
LIKELY BRING SNOW INTO SOUTHERN PENNSYLVANIA IN THE MIDDLE OF THE
WEEK.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
FORECAST STRONGLY CONTINUOUS...AND FLURRIES OR LIGHT SNOW EXPECTED
FOR THE ENTIRE NIGHT. RECENT HRRR AND RUC/RAP HAVE BEEN INDICATING
THAT WE COULD GET SOME ENHANCED LLVL OMEGA THIS EVENING AS AN
UPPER LEVEL LOW FILLS AND PASSES N-S THRU OH. WILL KEEP POPS HIGH
THEN PLAY A GRADUAL DECREASE IN POPS/SNOW INTENSITY AND AMOUNTS
AFTER MIDNIGHT. BUT THE FLOW DOES NOT CHANGE DIRECTION AND THE
PRES GRADIENT STAYS TIGHT. SHOULD BE BREEZY WITH 10MPH+ WINDS ALL
NIGHT. THE FLUFFINESS OF THE SNOW IN THIS DRY AIR MASS AND COLD
CLOUD TEMPS RESULTED IN SLR/S IN THE 30:1 RANGE SUN MORNING.
THEREFORE...ACCUMS OF A DUSTING TO AN INCH PROBABLE OVER THE NWRN
HALF OF THE AREA...WITH 1-3 IN THE FAR NRN TIER AND IN THE
LAURELS. TEMPS ALREADY BELOW NORMALS...BUT CLOUD COVER WILL HELP
TO KEEP THEM GOING TOO FAR BELOW NORMAL MINS BY MON MORNING.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
SFC HIGH PRESSURE RIDGE TO THE WEST INCHES CLOSER AND 5H HEIGHTS
RISE GREATLY OVER THE GREAT LAKES AND OH VALLEY AND SOMEWHAT HERE
AS WELL. LLVL PRES GRADIENT STAYS TIGHT DURING THE DAY AND MIXING
DEEPER THAN SUNDAY SHOULD ENHANCE THE WINDS IN THE AFTN. THE CLOUD
DECK WILL BECOME MORE-DIFFUSE THROUGH THE MORNING AND CLEARING
POSSIBLE ACROSS THE SOUTH AND EAST-CENTRAL COS IN THE AFTN. NW
FLOW STILL DOMINATES MUCH OF THE DAY...BUT RELAXES AND BECOMES
SLIGHTLY ANTI-CYCLONIC LATER IN THE DAY. THIS ALSO POINTS TO A
SUBSIDENCE OF THE SHSN...BUT THEY WILL LIKELY HOLD ON LONGEST IN
THE NRN TIER. CLOUDS WILL LINGER EVEN LONGER...PERHAPS STAYING
NEAR 100PCT THRU THE EVENING HRS. WILL CONTINUE TO MENTION LIGHT
ACCUMS AND LIKELY POPS IN THE MTNS IN THE MORNING...BUT TAPER THEM
OFF LATER. DUE TO THE POSSIBILITY OF SUN IN THE SRN TIER AND ESP
THE SE...TEMPS SHOULD GET A LITTLE MILDER - BUT STILL BELOW NORMAL
ON MONDAY AFTN.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
REX BLOCK FROM THE CANADIAN MARITIMES SOUTH TO THE NEW ENGLAND COAST
WILL TEMPORARILY BREAK DOWN AS A VIGOROUS CHUNK OF UPPER ENERGY
DIVES SOUTHEAST ACROSS THE ROCKIES AND CARVES OUT A POTENT UPPER LOW
CENTER...WHICH TRACKS EAST FROM THE MID MISS VALLEY TO THE MID
ATLANTIC COAST BY LATE WEDNESDAY NIGHT.
FOR MONDAY NIGHT AND TUESDAY...THE PERSISTENT/COLD NWRLY FLOW WILL
RELAX AND AT LEAST PARTIAL CLEARING WILL OCCUR AS A RIDGE OF HIGH
PRESSURE AT THE SFC AND ALOFT SLIDES EAST ACROSS THE COMMONWEALTH.
U.S. MODELS AND ENSEMBLES HOPEFULLY CAN HANDLE THE UPCOMING CRITICAL
/HOME COURT/ WEATHER FOR THE MID-WEEK PERIOD BETTER THAN THE
ADMIRABLE RECORD OF THE /VISITING TEAM/ MODELS.../EC AND UKMET/.
THE 00Z THROUGH 12Z SREF AND GEFS...ALONG WITH THE OPERATIONAL
NAM/GFS AND UKMET HAVE BEEN IN FAIRLY GOOD AGREEMENT AND CLUSTERED
FURTHER NORTH WITH THE SFC/UPR LOW TRACK AND RESULTANT NORTHERN EDGE
OF THE SHIELD OF HEAVY SNOW...COMPARED TO THE EC/UKMET WHICH BARELY
BRUSHES EXTREME SOUTHERN PA AND THE LAURELS WITH A FEW TO SVRL
INCHES OF SNOW LATE TUESDAY THROUGH WEDNESDAY.
THE FOCUS FOR OUR WEATHER...AND SOMEWHAT HIGH DEGREE OF CONFIDENCE
FOR THE SOUTHERN 1-2 LAYERS OF COUNTIES GETTING INTO THE NORTHERN
EDGE OF MDT TO HVY SNOW ACTION...RESTS ON THE VERIFICATION/PLACEMENT
OF THE CONSISTENT AND HIGHLY ANOMALOUS /-3 TO -4 SIGMA/ EASTERLY
925-850 MB FLOW THAT/S BEEN CONSISTENTLY SHOWN AND AIMED INTO
SOUTHERN PENN AND POINTS SOUTH THE PAST FEW ENSEMBLE AND U.S.
OPERATIONAL MODEL RUNS.
THE PASSAGE OF THE LEFT EXIT REGION OF A HIGHLY CYCLONIC AND STRONG
120+ KT 300 MB JET...AND ASSOCIATED/PERSISTENT 850-700 MB FGEN
FORCING ACROSS SRN PA SUPPORTS THE LIKELIHOOD OF AN EXTENDED...18-24
HR PERIOD OF ENHANCED SNOWFALL NEAR AND TO THE SOUTH OF ROUTE 22 IN
SCENT PENN.
ACROSS THE CENTRAL THIRD OF THE STATE...EXPECT LIGHTER SNOW OF A FEW
TO SEVERAL INCHES UP TO AROUND THE I-80 CORRIDOR.
THE LATEST ENSEMBLE GUIDANCE /06-12Z GEFS AND 03-15Z SREF/ CONTINUE
TO BE THE HIGH-END...NORTHERN OUTLIERS DISPLAYING A MEAN LIQUID
EQUIVALENT 24 HR QPF OF 0.5 OF AN INCH NEAR AND JUST TO THE SOUTH OF
I-80...WHILE EARLIER RUNS LEADING UP TO AND INCLUDING THE 12Z GEFS
DEPICTED THE 24 HR 1-INCH CONTOUR BRUSHING THE MASON DIXON LINE OF
SCENT AND SERN PA.
THE FRESH IN...15Z RUN OF THE SREF HAS TRENDED EVEN FARTHER NORTH
WITH THE MODERATE TO HEAVY QPF /AND POTENTIALLY VERY SNOWFALL/ AND
NOW PLACES THE 1 INCH QPF CONTOUR AS FAR NORTH AND WEST AS KUNV AND
KJST...EAST TO KLNS. THIS IS SUPPORTED BY A SLIGHT NORTHERN SHIFT
AND STRENGTHENING TO THE 850 EASTERLY JET...WHICH IS NOW SHOWN TO BE
A WHOPPING -5 TO -6 SIGMA ACROSS SERN PA AT 18Z WED. WON`T BUY INTO
THESE MUCH HIGHER AMOUNTS NORTH OF THE PENN TURNPIKE JUST YET...AND
WOULD RATHER TAKE THE MORE PRUDENT AND CONSERVATIVE ROUTE
CONSIDERING THE LARGE...AND PERSISTENT DISAGREEMENT BY THE 00Z-12Z
EURO MODELS WITH THEIR MORE SOUTHERN TRACK.
THE FEATURE THAT SEEMS TO BE ONE OF THE MOST CONSISTENT ON THE SREF
AND GEFS /SUPPORTING MODERATE TO HEAVY SNOW SPREADING ACROSS THE SRN
THIRD TO HALF OF PENN/ HAS BEEN THE TRACK OF THE 250 MB LOW CENTER
RIGHT OVER KCMH AND KMGW LATE TUESDAY NIGHT AND WED MORNING...WHICH
PLACES CENTRAL AND SOUTHERN PENN UNDER AN EXTREMELY DIFFLUENT UPPER
FLOW AND MAINTAINS A DEEP EAST TO NE FLOW LATE TUESDAY NIGHT THROUGH
MUCH OF WED.
THE MAIN CONCERN USING THE ENSEMBLE QPF MEAN /AND AMOUNTS TWD THE
NRN EDGE OF THE PRECIP SHIELD/ IS THE LIKELY CONTAMINATION/SKEWING
BY A FEW OF THE EXCESSIVELY HIGH END MEMBERS THAT SHOW OVER 2.0
INCHES OF LEQ FOR CENTRAL AND SOUTHERN PENN.
USING A /MEDIAN/ VALUE...OR MEAN BY REMOVING A FEW OF THE VERY HIGH
AND LOW END MEMBERS TRIMS SOME OF THE EXCESS FAT /SNOWFALL/ FROM THE
NRN EDGE. THIS IS NOT TO SAY THAT THESE FRINGE ENSEMBLE MEMBERS
DON/T PROVIDE VALUABLE INSIGHT INTO THE POTENTIAL MAGNITUDE OF THE
STORM. RATHER...ON THE WHOLE...THEY BROAD-BRUSH HIGHER AMOUNTS TOO
FAR TO THE NORTH.
THE LATEST HWOCTP INDICATES THE GENERAL EXPECTED SNOWFALL FROM NORTH
TO SOUTH ACROSS THE STATE...AND OUR GRIDDED STORM TOTAL SNOWFALL IS
CONSERVATIVELY PLACED A FAIR AMOUNT BELOW THE OPERATIONAL
GFS/NAM/SREF AND GEFS MEAN. INITIAL ESTIMATES OF STORM TOTAL
SNOWFALL VARY FROM JUST A FEW INCHES NEAR AND TO THE NE OF KIPT...TO
BETWEEN 8-11 INCHES ACROSS THE SOUTHERN TIER COUNTIES /WITH A
GENERAL 3-6 INCHES NEAR AND JUST TO THE SOUTH OF A SEG-KUNV-KFIG
LINE.
AGAIN...ALL EYES WILL BE ON THE TRENDS OF THE LATER RUNS...ESP THE
SOUTHERN OUTLIERS - EC AND UKMET.
A CHILLY AND RATHER GUSTY NORTHERLY FLOW WITH ISOLATED TO SCATTERED
MTN SNOW SHOWERS FOLLOWS FOR THURSDAY...BEFORE HEIGHTS RISE AND
DAYTIME TEMPS MODERATE TO NEAR NORMAL BY FRIDAY AND SATURDAY. A FAST
MOVING AND RELATIVELY FLAT/WEAK NRN STREAM SHORTWAVE WILL TRACK
ACROSS THE GREAT LAKES AND NRN PENN SATURDAY INTO SATURDAY
NIGHT...POSSIBLY ACCOMPANIED BY A FEW SHOWERS OF RAIN AND WET SNOW
UP NORTH. SOUTHERN PORTIONS OF PENN SHOULD STAY MAINLY DRY THROUGH
THE WEEKEND...AFTER THE POTENTIAL HIGH IMPACT/HEAVY SNOW EVENT OF
LATE TUESDAY INTO EARLY THURSDAY.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
PERSISTENCE FORECAST REMAINS THE PHRASE FOR THE FCST PERIOD.
CLIMO NW FLOW PATTERN YIELDS GENERALLY MVFR/IFR CIGS IN THE
BFD/JST AND MVFR IN AOO/UNV. DRYING ON DOWNSLOPE IMPROVES
CONDITIONS EVEN MORE IN IPT/MDT/LNS. PRES GRADIENT KEEPING WINDS
IN THE 10-15KT RANGE WITH OCCASIONAL GUSTS INTO THE 20S ALMOST
EVERYWHERE. THE GRADIENT DOES NOT SLACKEN THROUGH THE NIGHT NOR ON
MONDAY. WILL KEEP WINDS PERSISTENT AS WELL. THINGS TO PICK OUT AS
POTENTIAL ENHANCEMENTS TO THIS FORECAST ARE A SLIGHT INCREASE IN
UPSLOPE FLOW AND UPLIFT IN THE WRN MTS THIS EVENING. THIS HAS
RESULTED IN A FEW HOUR PERIOD OF WORSE FCST CONDITIONS FOR THOSE
LOCATIONS - BUT EVEN THAT NEVER DROPS ANY SITE TO LIFR. SOME IFR
VSBYS ARE LIKELY THE WORST OF THE THINGS TO DEAL WITH TONIGHT.
CIGS WILL PROBABLY HOLD ABOVE FL010 ALL NIGHT...EXCEPT PERHAPS AT
JST...BUT PROB SO LOW THAT I HAVE NOT INCLUDED IT WITH THIS PKG.
MONDAY BRINGS SIGNIFICANT IMPROVEMENT TO CLOUDS AND VSBYS. SFC
RIDGE TO THE WEST INCHES CLOSER AND WE LOSE THE CYCLONIC LLVL
FLOW...AS IT BECOMES MORE-NEUTRAL. LAKE MOISTURE STILL DRAWN DOWN
FROM THE N WILL KEEP THE CLOUDS OVER THE NRN TIER...BUT SERN
TERMINALS WILL CLEAR OUT BY THE LATE AFTN...AND EVEN JST MIGHT
SCT-OUT. HIGH PRES AXIS MAKES IT OVERHEAD TUES AM...AND LITTLE
CLOUD AND ONLY LIGHT WIND IN STORE.
OUTLOOK...
TUE...CLOUDS INCREASE W-E LATE.
TUE NIGHT-WED NIGHT...SIG RESTRICTIONS POSS S IN S+
THU...MVFR N...VFR ELSEWHERE.
FRI...NSW.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...LAMBERT
AVIATION...DANGELO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
239 PM EST SUN MAR 3 2013
.SYNOPSIS...
A SLOW MOVING UPPER LOW OVER THE NORTHEASTERN STATES WILL EXIT OFF
THE NEW ENGLAND COAST BY LATE MONDAY ALLOWING WEAK HIGH PRESSURE
TO BUILD ACROSS THE LOCAL AREA. LOW PRESSURE WILL DEVELOP IN THE
HIGH PLAINS SUNDAY AND MONDAY AND TAKE A TRACK THROUGH THE OHIO
VALLEY AND MID-ATLANTIC STATES TUESDAY NIGHT AND WEDNESDAY. THIS
STORM WILL PROBABLY PASS TO THE SOUTH OF THE STATE...BUT WILL MOST
LIKELY BRING SNOW INTO SOUTHERN PENNSYLVANIA IN THE MIDDLE OF THE
WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
FORECAST STRONGLY CONTINUOUS...AND FLURRIES OR LIGHT SNOW EXPECTED
FOR THE ENTIRE NIGHT. RECENT HRRR AND RUC/RAP HAVE BEEN INDICATING
THAT WE COULD GET SOME ENHANCED LLVL OMEGA THIS EVENING AS AN
UPPER LEVEL LOW FILLS AND PASSES N-S THRU OH. WILL KEEP POPS HIGH
THEN PLAY A GRADUAL DECREASE IN POPS/SNOW INTENSITY AND AMOUNTS
AFTER MIDNIGHT. BUT THE FLOW DOES NOT CHANGE DIRECTION AND THE
PRES GRADIENT STAYS TIGHT. SHOULD BE BREEZY WITH 10MPH+ WINDS ALL
NIGHT. THE FLUFFINESS OF THE SNOW IN THIS DRY AIR MASS AND COLD
CLOUD TEMPS RESULTED IN SLR/S IN THE 30:1 RANGE SUN MORNING.
THEREFORE...ACCUMS OF A DUSTING TO AN INCH PROBABLE OVER THE NWRN
HALF OF THE AREA...WITH 1-3 IN THE FAR NRN TIER AND IN THE
LAURELS. TEMPS ALREADY BELOW NORMALS...BUT CLOUD COVER WILL HELP
TO KEEP THEM GOING TOO FAR BELOW NORMAL MINS BY MON MORNING.
&&
.SHORT TERM /MONDAY/...
SFC HIGH PRESSURE RIDGE TO THE WEST INCHES CLOSER AND 5H HEIGHTS
RISE GREATLY OVER THE GREAT LAKES AND OH VALLEY AND SOMEWHAT HERE
AS WELL. LLVL PRES GRADIENT STAYS TIGHT DURING THE DAY AND MIXING
DEEPER THAN SUNDAY SHOULD ENHANCE THE WINDS IN THE AFTN. THE CLOUD
DECK WILL BECOME MORE-DIFFUSE THROUGH THE MORNING AND CLEARING
POSSIBLE ACROSS THE SOUTH AND EAST-CENTRAL COS IN THE AFTN. NW
FLOW STILL DOMINATES MUCH OF THE DAY...BUT RELAXES AND BECOMES
SLIGHTLY ANTI-CYCLONIC LATER IN THE DAY. THIS ALSO POINTS TO A
SUBSIDENCE OF THE SHSN...BUT THEY WILL LIKELY HOLD ON LONGEST IN
THE NRN TIER. CLOUDS WILL LINGER EVEN LONGER...PERHAPS STAYING
NEAR 100PCT THRU THE EVENING HRS. WILL CONTINUE TO MENTION LIGHT
ACCUMS AND LIKELY POPS IN THE MTNS IN THE MORNING...BUT TAPER THEM
OFF LATER. DUE TO THE POSSIBILITY OF SUN IN THE SRN TIER AND ESP
THE SE...TEMPS SHOULD GET A LITTLE MILDER - BUT STILL BELOW NORMAL
ON MONDAY AFTN.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
09Z UPDATE...
THE MAIN FOCUS OF THIS EXTENDED PERIOD CONTINUES TO BE MODEL
HANDLING OF MIDWEEK STORM SYSTEM...WHICH HAS THE POTENTIAL TO
BRING ACCUMULATING SNOWFALL TO CENTRAL AND SOUTHERN PA.
WITHOUT BEING TOO REACTIVE TO THE LATEST RUNS AND ENSEMBLES... IT
IS CLEAR THAT THE NAM/SREF/GFS/GEM ARE IN A DIFFERENT CAMP THAN
THE ECMWF...AS THE FORMER HAS TRENDED FARTHER NORTH OVER THE PAST
24 TO 36 HOURS WHILE THE EURO CONTINUES TO MIRROR PREVIOUS (2 DAY
OLD) RUNS OF THE GFS KEEPING MOST QPF SOUTH OF THE MASON/DIXON.
THINK THE OVERALL MESSAGE IS THAT THE AMERICAN AND CANADIAN MODELS
ARE KEEPING THE PRIMARY LOW STRONGER WITH DELAYED COASTAL PHASING...
PERHAPS QUITE SIMILAR TO THE LAST UNPHASED MILLER-B SYSTEM WE SAW
LAST FRIDAY. GFS EVEN INTRODUCES A DRY SLOT INTO WV WITH 850 TEMPS
ABOVE ZERO NOSING TOWARDS THE LAUREL HIGHLANDS EARLY WEDNESDAY AS
A RESULT OF THE DELAYED 2NDARY DEVELOPMENT. OF COURSE...3 DAYS OUT
THESE DETAILS WILL CHANGE...BUT IT`S WORTH ATTEMPTING TO DIAGNOSE
WHY OUR MODELS ARE SHIFTING QPF NORTHWARD WHILE THE PREVAILING
DOWNSTREAM BLOCK REMAINS IN PLACE...AND THE ECMWF FOR NOW ISN`T
SHOWING THE SAME TREND.
WITH THE ABOVE IN MIND...TWEAKED POPS...QPF AND SNOWFALL TOWARD
THE SREF AND GFS SOLUTIONS...BUT USED ONLY 50% OF THE GFS QPF AT
THIS TIME FOR THE SOUTHERN THIRD OF CENTRAL PA. SHOULD THE TREND
CONTINUE...IT IS POSSIBLE THAT CENTRAL PA BECOMES THE SWEET SPOT
BETWEEN THE DECAYING PRIMARY AND 2NDARY COASTAL DEVELOPMENT. AT
THIS TIME HOWEVER...STILL EXPECT THE GREATEST PROBABILITY OF HEAVY
SNOW OVER NORTHERN VIRGINIA AND MARYLAND...WHICH IS THE CONSENSUS
SOLUTION AT THIS TIME.
PREVIOUS DISCUSSION...
MODELS AND ENSEMBLES ARE COMING INTO BETTER AGREEMENT ON THE TRACK
OF THE MIDWEEK STORM HEADED OUR WAY FROM THE MID MISS VALLEY.
GRANTED...THERE/S STILL QUITE A BIT OF UNCERTAINTY...SINCE THE U.S.
MODELS...15Z AND 21Z SREF...ALONG WITH THE 06Z THROUGH 18Z GEFS HAVE
ALL TRENDED NORTH BY 50-100 NM WITH THE AXIS OF HEAVIEST QPF. THE
LATEST NAEFS AND EC ARE STILL ON THE SOUTHERN ENVELOPE OF SOLUTIONS
IN TRACKING THE SFC LOW NEAR OR JUST TO THE NORTH OF THE NC/WVA
LINE. THE NAEFS IS A TAD FURTHER NORTH...WHILE THE EC/S APPROX 530
DAM CLOSED LOW CENTER IS TAKEN ACROSS TENN AND NC. ALTHOUGH OUR
SOUTHERN COUNTIES ARE UNDER THE GUN FOR SOME POTENTIALLY HEAVY
SNOW...THE BIGGEST SIGNAL FOR AT LEAST SOME LIGHT SNOW ACROSS MUCH
OF CENTRAL /AND PERHAPS EVEN NCENT/ PENN IS THE BROAD AREA OF
ANOMALOUS EASTERLY LOW TO MID LEVEL FLOW BETWEEN THIS DEEP LOW...AND
THE OMEGA BLOCK ACROSS SERN CANADA.
THE MAIN THING TO EMPHASIZE AT THIS EARLY POINT IN TIME...IS THE
HIGH CONFIDENCE/POTENTIAL FOR A HIGH IMPACT STORM WITH HEAVY SNOW
SOMEWHERE ACROSS THE CENTRAL APPALACHIANS TO THE MID ATLANTIC
PIEDMONT...WITH OBVIOUSLY LESS CONFIDENCE IN THE STORM TRACK.
MODIFIED GRIDDED DATA TO INDICATE LIKELY POPS...WITH UP TO SEVERAL
INCHES OF STORM TOTAL SNOWFALL ACROSS THE SOUTHERN HALF OF PENN LATE
TUESDAY THROUGH WEDNESDAY.
PREVIOUS AFTERNOON DISCUSSION FOLLOWS...
PERSISTENT UPPER TROF OVER THE NORTHEASTERN UNITED STATES WILL GET
A QUICK REINFORCING SHOT OF COOLER AIR ON MONDAY BEFORE IT EXITS
TO THE NORTHEAST. LOWS SUN NIGHT WILL BE SLIGHTLY COOLER THAN THE
NIGHT BEFORE...WITH HIGHS MON JUST A FEW DEGREES HIGHER THAN SUNDAY.
TUESDAY A WEAK SFC RIDGE WILL BE IN PLACE OVER CENTRAL
PA...BRINGING QUIET WEATHER ALONG WITH WARMER TEMPERATURES.
VIGOROUS UPPER TROF WILL BE SLIDING ACROSS CENTRAL PLAINS
TUES...AND FCST TO DIVE SEWD TOWARD THE CAROLINAS...SPINNING UP A
SFC LOW OVER N CAROLINA/VIRGINA ON WED. HIGH LATITUDE BLOCKING AND
EASTWARD PROPAGATION OF SHORTWAVE ENERGY SHOULD KEEP CENTER OF
MAIN LOW TO OUR SOUTH...SLIPPING OFF THE COAST S OF DELMARVA.
SYSTEM WILL HAVE SOME PHASING ISSUES...WITH SECONDARY WEAKER SFC
LOW EDGING TOWARD W PA FROM OHIO VALLEY...BUT IMPACT TO EAST COAST
WILL BE CENTERED AROUND WED-WED NIGHT. MODELS STILL HAVE SOME
DIFFERENCES...BUT GENERALLY MORE IN LINE THAN PREVIOUS RUNS...WITH
A SOUTHERN TRACK BRINGING HEAVY SNOW TO THE VIRGINIA`S APPEARING
MOST LIKELY AT THIS TIME...WITH CONSENSUS AMONG 12Z MODELS TAKING
THE BULK OF QPF WELL SOUTH OF THE MASON DIXON LINE. AS
USUAL...EXPECT MODELS TO WAVER OVER THE NEXT SEVERAL DAYS...BUT
THE POTENTIAL EXISTS FOR SOME ACCUMULATING SNOW OR RAIN LATE
TUESDAY INTO WEDNESDAY NIGHT...BUT ALL OF THE MOST IMPORTANT
DETAILS REMAIN UNCLEAR AT THIS EARLY TIME.
BEHIND THIS SYSTEM FOR LATE WEEK INTO THE WEEKEND...MINIMAL COLD
AIR TO BE SEEN AS FLOW BECOMES WESTERLY. BY FRI...HIGHS SHOULD BE
IN THE 40S AREA-WIDE...AND SEVERAL DEGREES HIGHER ON SAT WITH A
PLEASANT SPRING DAY IN STORE.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
PERSISTENCE FORECAST REMAINS THE PHRASE FOR THE FCST PERIOD.
CLIMO NW FLOW PATTERN YIELDS GENERALLY MVFR/IFR CIGS IN THE
BFD/JST AND MVFR IN AOO/UNV. DRYING ON DOWNSLOPE IMPROVES
CONDITIONS EVEN MORE IN IPT/MDT/LNS. PRES GRADIENT KEEPING WINDS
IN THE 10-15KT RANGE WITH OCCASIONAL GUSTS INTO THE 20S ALMOST
EVERYWHERE. THE GRADIENT DOES NOT SLACKEN THROUGH THE NIGHT NOR ON
MONDAY. WILL KEEP WINDS PERSISTENT AS WELL. THINGS TO PICK OUT AS
POTENTIAL ENHANCEMENTS TO THIS FORECAST ARE A SLIGHT INCREASE IN
UPSLOPE FLOW AND UPLIFT IN THE WRN MTS THIS EVENING. THIS HAS
RESULTED IN A FEW HOUR PERIOD OF WORSE FCST CONDITIONS FOR THOSE
LOCATIONS - BUT EVEN THAT NEVER DROPS ANY SITE TO LIFR. SOME IFR
VSBYS ARE LIKELY THE WORST OF THE THINGS TO DEAL WITH TONIGHT.
CIGS WILL PROBABLY HOLD ABOVE FL010 ALL NIGHT...EXCEPT PERHAPS AT
JST...BUT PROB SO LOW THAT I HAVE NOT INCLUDED IT WITH THIS PKG.
MONDAY BRINGS SIGNIFICANT IMPROVEMENT TO CLOUDS AND VSBYS. SFC
RIDGE TO THE WEST INCHES CLOSER AND WE LOSE THE CYCLONIC LLVL
FLOW...AS IT BECOMES MORE-NEUTRAL. LAKE MOISTURE STILL DRAWN DOWN
FROM THE N WILL KEEP THE CLOUDS OVER THE NRN TIER...BUT SERN
TERMINALS WILL CLEAR OUT BY THE LATE AFTN...AND EVEN JST MIGHT
SCT-OUT. HIGH PRES AXIS MAKES IT OVERHEAD TUES AM...AND LITTLE
CLOUD AND ONLY LIGHT WIND IN STORE.
OUTLOOK...
TUE...CLOUDS INCREASE W-E LATE.
TUE NIGHT-WED NIGHT...SIG RESTRICTIONS POSS S IN S+
THU...MVFR N...VFR ELSEWHERE.
FRI...NSW.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...DEVOIR/LAMBERT/RXR
AVIATION...DANGELO
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