Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/26/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
835 PM MDT MON MAR 25 2013
.UPDATE...
&&
.SHORT TERM...NO CHANGES PLANNED TO ONGOING FORECAST. AIRMASS DRY
AND STABLE TONIGHT. THERE WILL BE SOME INCREASING HIGH CLOUDS FROM
THE WEST LATE TONIGHT AND SOME INCREASING GUSTY WINDS AS CROSS
MOUNTAIN FLOW INCREASES.
.AVIATION...NO ISSUES THIS EVENING WITH SOUTHERLY DRAINAGE WINDS
TONIGHT AND CLEAR SKIES. SOME CIRRUS INCREASING AFTER MIDNIGHT.
VFR TO CONTINUE.
&&
.PREV DISCUSSION... /ISSUED 308 PM MDT MON MAR 25 2013/
SHORT TERM...RIDGE BUILDING OVER WESTERN COLORADO WITH NORTHWEST
FLOW ACROSS CFWA. AIRMASS DRIER WITH WARM AIR ADVECTION OVER AREA.
WEB CAMS ACROSS MOUNTAINS HAVE SHOWN LINGERING SNOW SHOWERS HAVE
DISSIPATED. LATEST RAP CONTINUES TO INDICATE SOME LIGHT PRECIP
OVER PARK AND SUMMIT COUNTIES THROUGH 03Z. THIS SEEMS OVERDONE
GIVEN LATEST TRENDS. RIDGE WILL CONTINUE TO BUILD ACROSS COLORADO
TONIGHT WITH INCREASING HIGH LEVEL MOISTURE. TEMPERATURES TO BE A
FEW DEGREES WARMER THAN THIS MORNING`S READINGS. LATEST SYNTHETIC
SATELLITE LOOPS SHOWING SOME DEVELOPMENT OF A WAVE CLOUD ALONG
FOOTHILLS AFTER MIDNIGHT. WILL ADD A BIT MORE CLOUD TO THE GRIDS.
ON TUESDAY...FLOW ALOFT BECOMES A BIT MORE WESTERLY DURING THE
MORNING AS UPPER LEVEL DISTURBANCE MOVES INTO THE NORTHERN GREAT
BASIN. CROSS SECTIONS SHOW MOISTURE INCREASING ACROSS MOUNTAINS
ALONG WITH SOME INCREASE IN MID LEVEL QG ASCENT. LATEST MODELS
BEGIN BRINGING SOME LIGHT QPF AND SNOW ACCUMULATIONS TO THE
MOUNTAINS BY THE AFTERNOON. WILL INCLUDE SOME LOW POPS AFTER 15Z
ACROSS ZONE 31 AND WESTERN EDGE OF ZONE 34 IN SUMMIT COUNTY.
DURING THE AFTERNOON...MOISTURE AND INSTABILITY CONTINUES TO
INCREASE OVER THE MOUNTAINS. LATEST QG VERTICAL VELOCITY PROGS
SHOWS THE GREATEST LIFT OVER WESTERN UTAH. STILL SUFFICIENT LIFT
ALONG WITH LAPSE RATES AROUND 7 C/KG ENOUGH FOR A GOOD CHANCE OF
SNOW SHOWERS OVER THE HIGH COUNTRY. WILL KEEP ACCUMULATIONS LIGHT.
ALSO A CHANCE FOR RAIN AND SNOW SHOWERS ACROSS NORTH AND MIDDLE
PARKS. DOWNSLOPE FLOW ACROSS FOOTHILLS AND SOUTH PARK WILL HINDER
PRECIP CHANCES AND WILL CONTINUE THE SLIGHT CHANCE THERE. AS FOR
PLAINS...SOME INCREASE IN MID AND HIGH LEVEL MOISTURE THROUGH THE
DAY. LATEST GFS INDICATING SOME SHOWERS COULD MOVE ONTO URBAN
CORRIDOR LATE AFTERNOON...OTHER MODELS KEEP THINGS DRY. WILL
EXCLUDE THE SHOWERS AT THIS TIME. TEMPERATURE AND THICKNESS PROGS
SHOW HIGHS MODERATING SLIGHTLY...BUT CLOUDS AND SNOW COVER WILL
KEEP TEMPERATURES BELOW SEASONAL NORMALS.
LONG TERM...WEST-NORTHWESTERLY FLOW ALOFT IS PROGGED TUESDAY NIGHT
FOR THE CWA ALONG WITH A WEAK UPPER TROUGH TO MOVE ACROSS. AFTER
THAT...UPPER RIDGING IS OVER COLORADO WITH WEAKER ZONAL FLOW OVER
THE CWA WEDNESDAY THROUGH THURSDAY NIGHT. THERE IS WEAK UPWARD
VERTICAL VELOCITY PROGGED TUESDAY NIGHT...THEN BENIGN SYNOPTIC
SCALE ENERGY IS PROGGED THROUGH THURSDAY NIGHT. THERE IS A BIT OF
UPSLOPE PROGGED IN THE BOUNDARY LAYER FLOW FOR THE PLAINS AND
FOOTHILLS TUESDAY NIGHT INTO WEDNESDAY. AFTER THAT FAIRLY WEAK
NORMAL DIURNAL PATTERNS ARE PROGGED. FOR MOISTURE...THERE IS
PRETTY DECENT ALPINE MOISTURE TUESDAY NIGHT WITH THE WEAK TROUGH.
THERE IS SOME IN THE MID AND UPPER LEVELS OVER ALL OF THE CWA
WEDNESDAY THROUGH THURSDAY NIGHT. THE QPF FIELDS HAVE LIMITED
MEASURABLE PRECIPITATION MAINLY OVER THE MOUNTAINS TUESDAY NIGHT.
THERE IS A TINY BIT INDICATED ON WEDNESDAY INTO WEDNESDAY
EVENING. THERE IS ACTUALLY A BIT OF CAPE OVER THE MOUNTAINS
..FOOTHILLS AND WESTERN PLAINS WEDNESDAY AFTERNOON. VALUES ARE UP
TO 250 J/KG. WILL LEAVE IN OR GO WITH 30-60% POPS IN THE MOUNTAINS
ON TUESDAYNIGHT INTO WEDNESDAY...HIGHER POPS TUESDAY NIGHT.
THERE IS MOISTURE...A BIT OF OROGRAPHIC HELP...SOME SYNOPTIC SCALE
ENERGY AND FAIRLY STEEP LAPSE RATES. WEDNESDAY NIGHT AND THURSDAY
LOOK DRY. FOR TEMPERATURES...WEDNESDAY`S HIGHS ARE 1-4 C WARMER
THAN TUESDAY`S. THURSDAY`S HIGHS ARE 1-4 C WARMER THAN
WEDNESDAY`S. WILL CONTINUE THE TREND OF LOWER READINGS OVERALL AND
SEE WHAT THE SNOW FIELD OVER THE PLAINS DOES. FOR THE LATER
DAYS...FRIDAY THROUGH MONDAY...MODELS KEEP AN UPPER RIDGE AXIS
JUST WEST OF COLORADO FRIDAY AND SATURDAY. THE FLOW ALOFT IS WEST
OR NORTHWESTERLY AND PRETTY WEAK THOSE TWO DAYS. ON SUNDAY...THE
UPPER RIDGE AXIS IS PROGGED TO PUSH EASTWARD ACROSS COLORADO. BOTH
THE ECMWF AND GFS SHOW A CLOSED LOW OVER THE GREAT BASIN/DESERT
SOUTHWEST UNITED STATES BY MONDAY AFTERNOON. THERE IS QUITE A BIT
OF MOISTURE AROUND FRIDAY AND SATURDAY...THEN AGAIN MONDAY.
TEMPERATURES LOOK PRETTY MILD ALL FOUR DAYS.
AVIATION...LIGHT SOUTHEAST WINDS CURRENTLY ACROSS AREA AIRPORTS.
LATEST RAP AND HRRR CONTINUE TO SHOW LIGHT SOUTHEASTERLIES
CONTINUING INTO THE EVENING...THEN BECOMING SOUTHWEST AROUND 03Z
AS DRAINAGE FLOW DEVELOPS. SOME INCREASE IN HIGH LEVEL MOISTURE
AFTER MIDNIGHT WITH POTENTIAL FOR WAVE CLOUD DEVELOPING ALONG
FOOTHILLS BETWEEN 09Z AND 15Z. CEILINGS TO REMAIN ABOVE 12000
FEET AGL. VFR TO PREVAIL. ON TUESDAY...LIGHT SOUTHWEST WINDS TO
SHIFT TO THE SOUTHEAST AROUND 18Z WITH INCREASING MID AND HIGH
LEVEL CLOUDS. NO PRECIP EXPECTED WITH VFR CONTINUING. CEILINGS
AROUND 10000 FEET AGL EXPECTED THROUGH THE AFTERNOON.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...ENTREKIN
LONG TERM....RJK
AVIATION...ENTREKIN
AREA FORECAST DISCUSSION...CORRECTED
NWS DENVER/BOULDER CO
237 PM MDT SUN MAR 24 2013
...CORRECTED SPELLING ERRORS...
.SHORT TERM...A DISTURBANCE IN NW FLOW ALOFT WILL MOVE ACROSS THE
AREA THIS EVENING AS A BNDRY BRIEFLY ENHANCES UPSLOPE FLOW ALONG
THE FRONT RANGE. LAPSE RATES IN AND NR THE FOOTHILLS WILL BE
AROUND 8 C/KM. THUS WOULD EXPECT SNOW SHOWER ACTIVITY THRU THE
EARLY EVENING HOURS. BOTH THE RAP AND HRRR ARE SHOWING AMOUNTS IN
THE FOOTHILLS WEST AND SOUTHWEST OF DENVER UP TO 4 INCHES WITH UP
TO 2 INCHES IN THE WRN SUBURBS. FURTHER EAST AMOUNTS ARE IN AN
INCH OR LESS. ANOTHER AREA OF SNOW MAY RESIDE NR THE WY-CO BORDER
IN NR WELD COUNTY WHERE AN INCH OR TWO MAY FALL. IN THE MTNS WILL
CONTINUE TO SEE SOME OROGRAPHIC -SHSN WITH A FEW INCHES POSSIBLE
AS WELL. BY MIDNIGHT MOST ACTIVITY SHOULD END ALTHOUGH RAP SHOWS
SHOW LIGHT ACTIVITY NR THE WY BORDER.
ON MON DRIER AIR WILL BE OVER THE AREA IN NW FLOW ALOFT HOWEVER
SOME LINGERING MOISTURE IN THE MTNS MAY ALLOW FOR A SLIGHT CHC OF
-SHSN. AS FOR TEMPS WITH SFC HIGH PRES STILL OVER THE AREA AND
LINGERING SNOWPACK WILL KEEP HIGHS MAINLY IN THE UPPER 20S TO
LOWER 30S ACROSS NERN CO.
.LONG TERM...NORTHWESTERLY FLOW ALOFT IS TO DOMINATE THE FORECAST
AREA MONDAY NIGHT THROUGH TUESDAY...THEN UPPER RIDGING GETS OVER
THE STATE AND THE FLOW ALOFT IS ZONAL. THE SYNOPTIC SCALE ENERGY
PROGGED OVER THE CWA IS BENIGN ACCORDING TO THE Q-G VERTICAL
VELOCITY FIELDS MONDAY NIGHT THROUGH WEDNESDAY NIGHT. THE LOW
LEVEL WIND AND PRESSURE FIELDS SHOW NORMAL DIURNAL TRENDS
CONCERNING THE BOUNDARY LAYER WINDS MONDAY NIGHT THROUGH WEDNESDAY
NIGHT. MODELS HAVE LIMITED MOISTURE AROUND MONDAY NIGHT. ON
TUESDAY...MOISTURE INCREASES OVER THE MOUNTAINS AND IN THE MID AND
UPPER LEVELS OF THE PLAINS...ESPECIALLY ON THE GFS. THIS CONTINUE
INTO WEDNESDAY...BEFORE DRYING OUT SOMEWHAT WEDNESDAY NIGHT. THE QPF
FIELDS HAVE MINIMAL MEASURABLE PRECIPITATION NOTED...MOSTLY OVER THE
MOUNTAINS...TUESDAY AFTERNOON...THEN AGAIN WEDNESDAY INTO WEDNESDAY
EVENING. WILL GO WITH 20-40% POPS IN THE MOUNTAINS TUESDAY AFTERNOON
THROUGH WEDNESDAY EVENING. FOR TEMPERATURES... TUESDAY`S HIGHS ARE
ABOUT 6 C WARMER THAN MONDAY`S HIGHS. WEDENSDAY`S HIGHS ARE 1-3 C
WARMER THAN TUESDAY`S. FOR THE LATER DAYS...THURSDAY THROUGH
SUNDAY...NOW THE MODELS KEEP UPPER RIDGING OVER COLORADO ALL FOUR
DAYS. THE UPPER CLOSED LOW STAYS WELL WEST OF THE THE STATE THROUGH
SUNDAY ON THESE LATEST RUNS.
&&
.AVIATION...WILL STILL SEE A CHC OF SNOW SHOWERS THU 02Z WITH
ACCUMULATIONS AT DIA AN INCH OR LESS. AFER 02Z SNOW CHANCES SHOULD
DIMINISH WITH ONLY A FEW FLURRIES POSSIBLE. CEILINGS AND
VISIBILITIES MAY STILL DROP DOWN TO MVFR LVLS DUE TO SNOW THRU
02Z. AFTER 02Z WILL KEEP CEILINGS AROUND 6000 FT THRU 07Z. WINDS
SHOULD BE NNE THRU THE EARLY EVENING BUT THEN BECOME LIGHT SSWLY
AFTER 03Z THRU MON MORNING. ON MON EXPECT VFR CONDITIONS WITH
LIGHT SSE WINDS BY AFTN.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....RJK
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
931 AM MDT SUN MAR 24 2013
.UPDATE...
&&
.SHORT TERM...A DISTURBANCE IN NW FLOW ALOFT WILL MOVE ACROSS THE
AREA THIS AFTN INTO THE EARLY EVENING HOURS AS A BNDRY MOVES INTO
NERN CO ENHANCING UPSLOPE FLOW ALONG THE FRONT RANGE. LATEST DATA
DOES SHOW SOME MID LVL QG ASCENT THIS AFTN INTO THE EARLY EVENING
HOURS WITH LAPSE RATES IN AND NR THE FOOTHILLS AROUND 9 C/KM.
LATEST RAP SOUNDINGS BECOME MOIST ADIABATIC AS WELL. THUS WOULD
EXPECT SNOW SHOWER ACTIVITY TO INCREASE THIS AFTN AND CONTINUE
THRU THE EARLY EVENING HOURS. BOTH THE RAP AND HRRR ARE SHOWING
SOME DECENT SNOW AMOUNTS IN THE FOOTHILLS WEST AND SOUTHWEST OF
DENVER WITH AMOUNTS OF 4 TO 8 INCHES WITH UP TO 4 INCHES IN THE
WRN SUBURBS. FURTHER EAST AMOUNTS ARE IN THE 1 TO 2 INCH RANGE.
HAVE BUMPED UP SNOW AMOUNTS SOME BUT NOT QUITE AS HIGH AS THE RAP
IS SHOWING.
.AVIATION...WINDS SHOULD GRADUALLY BECOME MORE NNE BY 18Z AND
CONTINUE THRU THE EARLY EVENING HOURS. BEST CHC OF SNOW LOOKS TO
BE IN THE 23Z-03Z TIMEFRAME WHEN UP TO AN INCH OF SNOW MAY OCCUR
AT DIA. AT THIS TIME IT APPEARS HEAVIER AMOUNTS WILL STAY TO THE
WEST AND SW OF DIA WITH BJC AND APA SEEING UP TO 3 INCHES POSSIBLY.
CEILINGS AND VISIBILITIES MAY DROP DOWN TO IFR BETWEEN 23Z AND
03Z WITH SOME LIFR AT BJC AND APA. SNOW THREAT SHOULD GRADUALLY
DECREASE AROUND 03Z AT DIA AND BJC BUT MAY LINGER THROUGH 05Z AT
APA.
&&
.PREV DISCUSSION... /ISSUED 344 AM MDT SUN MAR 24 2013/
SHORT TERM...NORTHWEST FLOW ALOFT WILL BE OVER THE STATE TODAY
AS AN UPPER LOW SPINS OVER THE GREAT PLAINS. A DISTURBANCE MOVING
AROUND THIS LOW WILL PASS OVERHEAD TODAY TO INCREASE CHANCES FOR
SNOW AGAIN TODAY. A SLIGHT SURGE FROM THE NORTH TURNING WINDS
UPSLOPE OVER THE PLAINS...ALONG WITH SLIGHT INSTABILITY IN THE
AIRMASS TODAY AND JUST ENOUGH MOISTURE WILL AID IN THE LIKELY
CHANCES FOR SNOW ACCUMULATION. THE MOUNTAINS ARE ALREADY SEEING
LIGHT SNOW EARLY THIS MORNING IN THE FAVORED NORTHWEST FLOW...THEN
SNOWFALL RATES WILL BE INCREASING THROUGH THE DAY AS THE
DISTURBANCE PASSES. A TOTAL OF 2 TO 5 INCHES WILL LIKELY FALL
THROUGH THE DAY AND INTO THE NIGHT...WITH THE HIGHER AMOUNTS FOUND
NORTH OF I-70 ALONG WEST FACING SLOPES. AS FOR THE PLAINS...THE
SURGE FROM THE NORTH IS EXPECTED LATE THIS MORNING. THIS WILL AID
IN GETTING SHOWERS TO BEGIN MORNING BY EARLY AFTERNOON. THERE MAY
BE A BIT OF DOWNSLOPING TO FIGHT WITH NORTHWEST FLOW
ALOFT...HOWEVER WITH THE INSTABILITY AND THE COMPLEXITIES THAT
ALWAYS SHOW WITH NORTHWEST FLOW...SHOULD SEE LIGHT SNOW OVER MOST
OF THE PLAINS WITH SLIGHTLY HIGHER AMOUNTS OVER THE URBAN CORRIDOR
DOWN TO THE PALMER DIVIDE. TOTAL SNOWFALL AMOUNTS ARE EXPECTED TO
BE QUITE LIGHT COMPARED TO WHAT WE JUST EXPERIENCED...GENERALLY
BELOW 2 INCHES.
TEMPERATURES WILL REMAIN COLDER THAN NORMAL BY AROUND 30 DEGREES
TODAY. READINGS IN THE 20S AGAIN FOR THE PLAINS AND IN THE TEENS
FOR THE MOUNTAINS. MINIMUM TEMPERATURES WILL BE COLD AGAIN AS WELL
WITH SINGLE DIGIT TO BELOW ZERO READINGS. LIGHT WINDS WILL
PREVAIL.
LONG TERM...SUBSIDENCE WILL INCREASE ACROSS THE FORECAST AREA
MONDAY WITH DRIER AIR TAKING HOLD. THERE IS STILL A LITTLE
MOISTURE IN/NEAR THE MOUNTAINS LINGERING INTO MONDAY MORNING...AND
A BIT OF SHALLOW INSTABILITY IN THE MOUNTAINS DURING THE
AFTERNOON...SO WILL KEEP SOME LOW POPS FOR THAT. OTHERWISE LOOK
FOR SOME SUNSHINE TO RETURN. HOWEVER...TEMPERATURES WILL REMAIN
MUCH BELOW NORMAL AND WILL HAVE A HARD TIME EVEN APPROACHING THE
FREEZING MARK. LOWS MONDAY NIGHT SHOULD DROP INTO THE SINGLE
DIGITS AGAIN ON THE PLAINS WITH MOSTLY CLEAR SKIES...WITH BELOW
ZERO READINGS IN THE HIGH COUNTRY.
BY TUESDAY...FLOW ALOFT BECOME MORE WESTERLY WHICH WILL BEGIN A
SLOW WARMING TREND. IT WILL TAKE A FEW DAYS TO MELT THE SNOW
COVER...SO THE GOING CONSERVATIVE TEMPERATURE FORECAST THROUGH MID
WEEK IS GOOD ESPECIALLY CONSIDERING THE LOW LEVEL EASTERLY FLOW
WITH COLD HIGH PRESSURE RESIDING OVER THE CENTRAL PLAINS.
MEANWHILE...THE CURRENT UPPER LOW SPINNING IN THE EASTERN PACIFIC
GETS CAUGHT UP IN THE WESTERLY FLOW AND GRADUALLY SHEARS OUT.
HOWEVER...THERE IS ENOUGH MOISTURE TO WARRANT SOMEWHAT HIGHER POPS
IN THE MOUNTAINS BEGINNING TUESDAY AND CONTINUING INTO WEDNESDAY.
THE CHANCE FOR ANY PRECIPITATION SPILLING ONTO THE PLAINS IS QUITE
LOW GIVEN THE WESTERLY FLOW ALOFT SO HAVE KEPT THE LOWER
ELEVATIONS DRY FOR NOW.
BY THURSDAY...SOME AMPLIFICATION OF THE UPPER RIDGE IS EXPECTED SO
THAT SHOULD BE A MAINLY DRY DAY. THERE IS CONSIDERABLE UNCERTAINTY
WITH REGARD TO EVOLUTION OF THE WEATHER PATTERN LATE IN THE WEEK
INTO NEXT WEEKEND. THERE IS POTENTIAL FOR A DECENT SURGE AT SOME
POINT SO IT SEEMS PRUDENT TO MENTION COOLER TEMPERATURES AND A
SLIGHT CHANCE OF SHOWERS BY THE WEEKEND.
AVIATION...WITH MOSTLY CLEAR SKIES EARLY THIS MORNING...THERE
WILL STILL BE A POSSIBILITY OF PATCHY FOG AT THE AIRPORTS UNTIL A
COUPLE HOURS AFTER SUNRISE. HOWEVER DRIER DEWPOINTS MOVING IN MAY
HELP KEEP IT FROM FORMING. WILL KEEP THE VCFG IN THE TAFS AT THIS
POINT AND MONITOR OBSERVATIONS...WEBCAMS AND SATELLITE. A PUSH
FROM THE NORTH TODAY WILL HELP TURN SURFACE WINDS SLIGHTLY UPSLOPE
BY NOON. WITH NORTHWEST FLOW ALOFT...SLIGHT INSTABILITY AND ENOUGH
MOISTURE AROUND...MAY SEE LIGHT SNOW SHOWERS AS EARLY AS 22Z WITH
A SHOWERS LIKELY TURNING TO MORE WIDESPREAD SNOW THROUGH 03Z. IFR
CONDITION EXPECTED UNDER THE SNOW WHERE IT DEVELOPS. WILL
CONTINUE TO MONITOR THE DEVELOPMENT OF THIS DISTURBANCE.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BARJENBRUCH
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1002 PM CDT MON MAR 25 2013
.DISCUSSION...
819 PM CDT
LAKE EFFECT SNOW SHOWERS CONTINUE TO STREAM ONSHORE ACROSS
SOUTHEAST COOK...LAKE...AND PORTER COUNTIES. LATEST RADAR TRENDS
AND OBS SHOW SOME BETTER ORGANIZATION WHICH IS SUPPORTED BY NEAR
TERM RAP SOUNDINGS THAT SHOW INVERSION HEIGHTS RISING CLOSER TO
7000 FT. 00Z GREEN BAY RAOB SHOWS AN INVERSION AROUND 6800 FT
WITH AN H85 TEMP AT -11C WITH LAKE WATER TEMP ROUGHLY AROUND +3C
YIELDING A 14C DIFFERENCE. LOW LEVEL WINDS HAVE BEGUN TO TURN MORE
NORTHWESTERLY...AT LEAST SLIGHTLY...OVER THE LAST FEW HOURS WHICH
SUPPORTS A GRADUAL EASTWARD SHIFT IN THE MORE FOCUSED ACTIVITY AND
BETTER RETURNS HAVE BEEN OCCURRING OVER PORTER COUNTY. OVERALL THE
GOING FORECAST REFLECTS THE ABOVE SO WILL ONLY MAKE MINOR TWEAKS
FOR NOW. STILL EXPECT THAT A FEW INCHES OF ACCUMULATION IS
POSSIBLE THROUGH THE OVERNIGHT ACROSS PORTER COUNTY BUT COVERAGE
OF ACCUMS MAY BE SOMEWHAT ISOLATED WITH MORE WIDESPREAD LIGHTER
AMOUNTS POSSIBLE GIVEN THE TRANSIENT NATURE OF THE BANDS.
ELSEWHERE...FLURRIES CONTINUE WITH NORTH-NORTHWEST WINDS EASING.
HAVE ADJUSTED TEMP TRENDS TO SUPPORT A SLOWER FALL INTO THE
OVERNIGHT.
MDB
//PREV DISCUSSION...
318 PM CDT
MAIN CONCERNS THIS FORECAST CYCLE ARE INITIALLY LAKE EFFECT SNOW
SHOWER TRENDS INTO TUESDAY...AND THEN TIMING OF NEXT COLD FRONT OVER
THE WEEKEND AND ASSOCIATED CHALLENGES OF TEMPS.
BROAD UPPER TROUGH DOMINATES THE EASTERN CONUS THIS AFTERNOON WITH
CLOSED LOW WHICH BROUGHT HEAVY SNOW TO THE MIDWEST ON SUNDAY/SUNDAY
NIGHT NOW PROPAGATING ACROSS THE MID-ATLANTIC REGION. SURFACE LOW
PRESSURE CONTINUES TO FILL OVER THE APPALACHIANS AS COASTAL LOW
DEEPENS OFF THE JERSEY SHORE...WITH BROAD AREA OF COOL CYCLONIC LOW
LEVEL FLOW TRAILING ACROSS THE GREAT LAKES AND MISSISSIPPI VALLEY
REGION. THIS HAS PRODUCED PERSISTENT FLURRIES/LIGHT SNOW SHOWERS
WITH STEEP LOW LEVEL LAPSE RATES...AS WELL AS LAKE EFFECT SNOW
SHOWERS WHICH HAVE GRADUALLY BECOME BETTER ORGANIZED THIS AFTERNOON.
LIGHT SNOW SHOWERS HAVE GENERALLY BEEN DECREASING ACROSS AREAS AWAY
FROM THE LAKE THIS AFTERNOON WITH WEAK SYNOPTIC SUBSIDENCE/HEIGHT
RISES IN THE WAKE OF THE SHEARED MID-LEVEL VORT DRIFTING SOUTH AWAY
FROM OUR AREA...THOUGH FORECAST SOUNDINGS SUPPORT CONTINUED STRATOCU
LINGERING TONIGHT WHICH WILL PROBABLY STILL PRODUCE SOME SCATTERED
INCONSEQUENTIAL FLURRIES AT TIMES. GUIDANCE DOES INDICATE A WEAK MID
LEVEL SHORT WAVE WILL APPROACH FROM THE NORTH/NORTHWEST LATE TONIGHT
AND WILL CROSS THE AREA TUESDAY MORNING...WHICH ALTHOUGH NO
SIGNIFICANT QPF IS INDICATED WILL LIKELY CONTINUE TO SUPPORT SOME
FLURRIES INTO TUESDAY MORNING. AS FOR THE LAKE EFFECT...BOUNDARY
LAYER WINDS ARE STARTING TO BACK FROM NORTHEAST TO MORE NORTHERLY...
AND WERE HELPING FOCUS CONVERGENCE FOR A NORTH-SOUTH LAKE-PARALLEL
BAND TO BECOME EVIDENT IN REGIONAL RADAR IMAGERY. WINDS CONTINUE TO
BACK GRADUALLY TO MORE NORTHWEST THROUGH TUESDAY MORNING WHICH
SHOULD ALLOW THIS BAND TO SHIFT ACROSS NORTHWEST INDIANA AND
EVENTUALLY EAST OF PORTER COUNTY AND OUT OF OUR CWA TUESDAY
AFTERNOON. THERMODYNAMIC PROFILES REMAIN FAIRLY MARGINAL FOR STRONG
LAKE EFFECT...WITH DELTA T VALUES GRADUALLY APPROACHING +14 OR SO
AND WITH EQUILIBRIUM LEVELS 6000-7000 FT. THUS WHILE ACCUMULATIONS
ARE NOT EXPECTED TO BE GREAT...WEAK LES EVENT IS EXPECTED TO PERSIST
AND HAVE BUMPED UP POPS ESPECIALLY OVER NORTHWEST INDIANA
TONIGHT/EARLY TUES. WITH LIGHT SNOW AND TEMPS ABOVE FREEZING NOT
MUCH ACCUMULATING ATTM...THOUGH ACCUMULATIONS OF AN INCH OR TWO ARE
LIKELY OVERNIGHT WITH SLIGHTLY COOLER TEMPS AND MORE ORGANIZED BAND.
BEYOND TUESDAY...UPPER FLOW REMAINS NORTHWEST WHILE HEIGHTS
GRADUALLY INCREASE AS EASTERN TROUGH SLOWLY MOVES AWAY. WEAK SURFACE
HIGH PRESSURE RIDGE MOVES INTO THE AREA BY LATE WEDNESDAY AND
THURSDAY WHICH WILL PROVIDE DRY WEATHER WITH SLOWLY MODERATING
TEMPS...LIKELY REACHING THE MID 40S BY THURSDAY.
GUIDANCE IS IN GOOD AGREEMENT IN DEPICTING AN UPPER TROUGH DROPPING
OUT OF CANADA AND AMPLIFYING ACROSS THE UPPER MIDWEST THIS WEEKEND.
SURFACE LOW PRESSURE INITIALLY DEVELOPS TO OUR NORTH/NORTHWEST ON
SATURDAY...WHICH ALLOWS OUR LOW LEVEL FLOW TO BECOME SOUTHERLY AS
THE SURFACE RIDGE DRIFTS AWAY TO THE EAST. WARMING COMMENCES... WITH
GUIDANCE INDICATING UPPER 40S/LOW 50S BY THE WEEKEND. MODELS REMAIN
A BIT CONFLICTED IN THE LONGER TERM WITH HOW QUICKLY THE COLD FRONT
ASSOCIATED WITH THE UPPER MIDWEST/LAKE LOW MOVES THROUGH HOWEVER.
THE GFS...WHILE CONSISTENT WITH ITSELF IS QUICKEST AND MOVES THE
FRONT THROUGH SATURDAY NIGHT...WHILE THE ECMWF BRINGS IT THROUGH
DURING THE DAY SUNDAY. THIS HAS SIGNIFICANT IMPLICATIONS ON TEMPS
ESPECIALLY SUNDAY...WITH ANOTHER DAY OF 50 DEGREE WARMTH ON SUNDAY
WITH THE SLOWER ECMWF SOLUTION. HAVE LEANED IN FAVOR OF THE USUALLY
CONSISTENT PERFORMING ECMWF...WITH 50S ACROSS THE SOUTHEAST 2/3 OR
SO OF THE CWA SUNDAY WITH NEAR 50 NORTHWEST CLOSER TO APPROACHING
FRONT. IN EITHER CASE...IT APPEARS THAT OUR THERMAL PROFILES WILL BE
WARM ENOUGH TO RESULT IN FRONTAL/PRE-FRONTAL PRECIP FALLING IN THE
FORM OF RAIN SATURDAY NIGHT INTO SUNDAY...PERHAPS MIXING WITH WET
SNOW BEFORE ENDING BEHIND THE FRONT SUNDAY NIGHT. EARLY NEXT WEEK
SHOWS EVEN BIGGER DIFFERENCES IN EVOLUTION OF PATTERN WITH THE GFS
REBUILDING WARMTH QUICKLY...WHILE THE ECMWF INDICATES MORE OF A COOL
DOWN BACK TO SUB-NORMAL TEMPS BEHIND THE FRONT MONDAY. 12Z EC NOT AS
COLD AS THE 00Z RUN...THOUGH HAVE AGAIN SHADED AWAY FROM THE 50S AS
PRODUCED BY THE GFS. WILL PULL FOR THE WARMER GFS SOLUTION HOWEVER!
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* VARIABLE MVFR/VFR CIGS WITH PERIODIC LIGHT SNOW OR FLURRIES.
BMD
//DISCUSSION...UPDATED 00Z...
PATTERN DOES NOT CHANGE MUCH THROUGH THE FORECAST PERIOD WHICH IS
EXPECTED TO BE DOMINATED BY BREEZY NORTHERLY FLOW...VARIABLE
MVFR/VFR CIGS AND PERIODIC FLURRIES. DEEP AREA OF LOW PRESSURE OFF
THE MID ATLANTIC COAST THIS EVENING WILL KEEP BROAD CYCLONIC FLOW
WITH NORTH/NORTHWEST WINDS AND A COLD AIRMASS IN PLACE OVER NORTHERN
ILLINOIS AND NORTHWEST INDIANA. HIGH PRESSURE OVER THE CENTRAL
PLAINS WILL GRADUALLY BUILD EAST THROUGH THE PERIOD...ALLOWING WINDS
TO CONTINUE TO BACK SLIGHTLY TO THE NORTHWEST AND UNDERGO A GRADUAL
WEAKENING TREND. EXPECT STRATUS TO LINGER THROUGH THE FORECAST
PERIOD...WITH LIKELY DIURNALLY DRIVEN BASES THAT SHOULD DROP SOLIDLY
BACK INTO MVFR CATEGORY OVERNIGHT...THEN LIFT BACK TO HIGH END MVFR
OR LOWER VFR DURING THE DAY TUESDAY. LAKE EFFECT SNOW WILL LIKELY
CONTINUE THROUGH THE NIGHT BUT SHOULD GRADUALLY CONTINUE TO SHIFT
EAST AS WINDS BACK TO THE NORTHWEST. MORE WIDESPREAD FLURRIES AND
LIGHT SNOW ARE ALSO EXPECTED TO BE LARGELY DIURNALLY DRIVEN...WITH
LOW LEVEL LAPSE RATES INCREASING DURING THE DAY. AN UPPER LEVEL
DISTURBANCE DROPPING SOUTH ACROSS THE AREA LATE TUESDAY
MORNING/EARLY AFTERNOON MAY ALSO HELP THE SNOW POTENTIAL BUT OVERALL
FORCING WITH THIS WAVE IS WEAK AND THERE IS NO REINFORCING COLD AIR
NOTED. OVERALL EXPECT SNOW TO BE LIGHT ENOUGH THAT IT WILL NOT
IMPACT VSBY OR ACCUMULATE.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* MEDIUM CONFIDENCE IN CIG TRENDS...LOW CONFIDENCE IN MFVR
OVERNIGHT.
* MEDIUM TO HIGH CONFIDENCE IN WIND SPEEDS...HIGH CONFIDENCE IN
DIRECTION.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...MVFR IMPROVING TO VFR.
THURSDAY...VFR.
FRIDAY...VFR.
SATURDAY...VFR.
SUNDAY...CHANCE OF RAIN/MFVR.
BMD
&&
.MARINE...
225 PM CDT
STRONG LOW PRESSURE OFF THE MID ATLANTIC COAST WILL MOVE EAST OUT
INTO THE ATLANTIC OCEAN WITH HIGH PRESSURE OVER THE PLAINS BUILDING
EAST INTO THE MISSISSIPPI VALLEY AND WESTERN GREAT LAKES. STRONG
NORTHERLY FETCH WILL KEEP WAVES UP FOR THE NEARSHORE THROUGH TUESDAY
OR TUESDAY NIGHT. FAIRLY LIGHT WINDS ARE EXPECTED WEDNESDAY THROUGH
FRIDAY AS HIGH PRESSURE SETS UP CAMP OVER THE REGION BEFORE SCOOTING
EAST OVER THE WEEKEND ALLOWING FOR SOUTHERLY WINDS TO DEVELOP.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 7 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
822 PM CDT MON MAR 25 2013
.DISCUSSION...
819 PM CDT
LAKE EFFECT SNOW SHOWERS CONTINUE TO STREAM ONSHORE ACROSS
SOUTHEAST COOK...LAKE...AND PORTER COUNTIES. LATEST RADAR TRENDS
AND OBS SHOW SOME BETTER ORGANIZATION WHICH IS SUPPORTED BY NEAR
TERM RAP SOUNDINGS THAT SHOW INVERSION HEIGHTS RISING CLOSER TO
7000 FT. 00Z GREEN BAY RAOB SHOWS AN INVERSION AROUND 6800 FT
WITH AN H85 TEMP AT -11C WITH LAKE WATER TEMP ROUGHLY AROUND +3C
YIELDING A 14C DIFFERENCE. LOW LEVEL WINDS HAVE BEGUN TO TURN MORE
NORTHWESTERLY...AT LEAST SLIGHTLY...OVER THE LAST FEW HOURS WHICH
SUPPORTS A GRADUAL EASTWARD SHIFT IN THE MORE FOCUSED ACTIVITY AND
BETTER RETURNS HAVE BEEN OCCURRING OVER PORTER COUNTY. OVERALL THE
GOING FORECAST REFLECTS THE ABOVE SO WILL ONLY MAKE MINOR TWEAKS
FOR NOW. STILL EXPECT THAT A FEW INCHES OF ACCUMULATION IS
POSSIBLE THROUGH THE OVERNIGHT ACROSS PORTER COUNTY BUT COVERAGE
OF ACCUMS MAY BE SOMEWHAT ISOLATED WITH MORE WIDESPREAD LIGHTER
AMOUNTS POSSIBLE GIVEN THE TRANSIENT NATURE OF THE BANDS.
ELSEWHERE...FLURRIES CONTINUE WITH NORTH-NORTHWEST WINDS EASING.
HAVE ADJUSTED TEMP TRENDS TO SUPPORT A SLOWER FALL INTO THE
OVERNIGHT.
MDB
&&
.PREV DISCUSSION...
318 PM CDT
MAIN CONCERNS THIS FORECAST CYCLE ARE INITIALLY LAKE EFFECT SNOW
SHOWER TRENDS INTO TUESDAY...AND THEN TIMING OF NEXT COLD FRONT OVER
THE WEEKEND AND ASSOCIATED CHALLENGES OF TEMPS.
BROAD UPPER TROUGH DOMINATES THE EASTERN CONUS THIS AFTERNOON WITH
CLOSED LOW WHICH BROUGHT HEAVY SNOW TO THE MIDWEST ON SUNDAY/SUNDAY
NIGHT NOW PROPAGATING ACROSS THE MID-ATLANTIC REGION. SURFACE LOW
PRESSURE CONTINUES TO FILL OVER THE APPALACHIANS AS COASTAL LOW
DEEPENS OFF THE JERSEY SHORE...WITH BROAD AREA OF COOL CYCLONIC LOW
LEVEL FLOW TRAILING ACROSS THE GREAT LAKES AND MISSISSIPPI VALLEY
REGION. THIS HAS PRODUCED PERSISTENT FLURRIES/LIGHT SNOW SHOWERS
WITH STEEP LOW LEVEL LAPSE RATES...AS WELL AS LAKE EFFECT SNOW
SHOWERS WHICH HAVE GRADUALLY BECOME BETTER ORGANIZED THIS AFTERNOON.
LIGHT SNOW SHOWERS HAVE GENERALLY BEEN DECREASING ACROSS AREAS AWAY
FROM THE LAKE THIS AFTERNOON WITH WEAK SYNOPTIC SUBSIDENCE/HEIGHT
RISES IN THE WAKE OF THE SHEARED MID-LEVEL VORT DRIFTING SOUTH AWAY
FROM OUR AREA...THOUGH FORECAST SOUNDINGS SUPPORT CONTINUED STRATOCU
LINGERING TONIGHT WHICH WILL PROBABLY STILL PRODUCE SOME SCATTERED
INCONSEQUENTIAL FLURRIES AT TIMES. GUIDANCE DOES INDICATE A WEAK MID
LEVEL SHORT WAVE WILL APPROACH FROM THE NORTH/NORTHWEST LATE TONIGHT
AND WILL CROSS THE AREA TUESDAY MORNING...WHICH ALTHOUGH NO
SIGNIFICANT QPF IS INDICATED WILL LIKELY CONTINUE TO SUPPORT SOME
FLURRIES INTO TUESDAY MORNING. AS FOR THE LAKE EFFECT...BOUNDARY
LAYER WINDS ARE STARTING TO BACK FROM NORTHEAST TO MORE NORTHERLY...
AND WERE HELPING FOCUS CONVERGENCE FOR A NORTH-SOUTH LAKE-PARALLEL
BAND TO BECOME EVIDENT IN REGIONAL RADAR IMAGERY. WINDS CONTINUE TO
BACK GRADUALLY TO MORE NORTHWEST THROUGH TUESDAY MORNING WHICH
SHOULD ALLOW THIS BAND TO SHIFT ACROSS NORTHWEST INDIANA AND
EVENTUALLY EAST OF PORTER COUNTY AND OUT OF OUR CWA TUESDAY
AFTERNOON. THERMODYNAMIC PROFILES REMAIN FAIRLY MARGINAL FOR STRONG
LAKE EFFECT...WITH DELTA T VALUES GRADUALLY APPROACHING +14 OR SO
AND WITH EQUILIBRIUM LEVELS 6000-7000 FT. THUS WHILE ACCUMULATIONS
ARE NOT EXPECTED TO BE GREAT...WEAK LES EVENT IS EXPECTED TO PERSIST
AND HAVE BUMPED UP POPS ESPECIALLY OVER NORTHWEST INDIANA
TONIGHT/EARLY TUES. WITH LIGHT SNOW AND TEMPS ABOVE FREEZING NOT
MUCH ACCUMULATING ATTM...THOUGH ACCUMULATIONS OF AN INCH OR TWO ARE
LIKELY OVERNIGHT WITH SLIGHTLY COOLER TEMPS AND MORE ORGANIZED BAND.
BEYOND TUESDAY...UPPER FLOW REMAINS NORTHWEST WHILE HEIGHTS
GRADUALLY INCREASE AS EASTERN TROUGH SLOWLY MOVES AWAY. WEAK SURFACE
HIGH PRESSURE RIDGE MOVES INTO THE AREA BY LATE WEDNESDAY AND
THURSDAY WHICH WILL PROVIDE DRY WEATHER WITH SLOWLY MODERATING
TEMPS...LIKELY REACHING THE MID 40S BY THURSDAY.
GUIDANCE IS IN GOOD AGREEMENT IN DEPICTING AN UPPER TROUGH DROPPING
OUT OF CANADA AND AMPLIFYING ACROSS THE UPPER MIDWEST THIS WEEKEND.
SURFACE LOW PRESSURE INITIALLY DEVELOPS TO OUR NORTH/NORTHWEST ON
SATURDAY...WHICH ALLOWS OUR LOW LEVEL FLOW TO BECOME SOUTHERLY AS
THE SURFACE RIDGE DRIFTS AWAY TO THE EAST. WARMING COMMENCES... WITH
GUIDANCE INDICATING UPPER 40S/LOW 50S BY THE WEEKEND. MODELS REMAIN
A BIT CONFLICTED IN THE LONGER TERM WITH HOW QUICKLY THE COLD FRONT
ASSOCIATED WITH THE UPPER MIDWEST/LAKE LOW MOVES THROUGH HOWEVER.
THE GFS...WHILE CONSISTENT WITH ITSELF IS QUICKEST AND MOVES THE
FRONT THROUGH SATURDAY NIGHT...WHILE THE ECMWF BRINGS IT THROUGH
DURING THE DAY SUNDAY. THIS HAS SIGNIFICANT IMPLICATIONS ON TEMPS
ESPECIALLY SUNDAY...WITH ANOTHER DAY OF 50 DEGREE WARMTH ON SUNDAY
WITH THE SLOWER ECMWF SOLUTION. HAVE LEANED IN FAVOR OF THE USUALLY
CONSISTENT PERFORMING ECMWF...WITH 50S ACROSS THE SOUTHEAST 2/3 OR
SO OF THE CWA SUNDAY WITH NEAR 50 NORTHWEST CLOSER TO APPROACHING
FRONT. IN EITHER CASE...IT APPEARS THAT OUR THERMAL PROFILES WILL BE
WARM ENOUGH TO RESULT IN FRONTAL/PRE-FRONTAL PRECIP FALLING IN THE
FORM OF RAIN SATURDAY NIGHT INTO SUNDAY...PERHAPS MIXING WITH WET
SNOW BEFORE ENDING BEHIND THE FRONT SUNDAY NIGHT. EARLY NEXT WEEK
SHOWS EVEN BIGGER DIFFERENCES IN EVOLUTION OF PATTERN WITH THE GFS
REBUILDING WARMTH QUICKLY...WHILE THE ECMWF INDICATES MORE OF A COOL
DOWN BACK TO SUB-NORMAL TEMPS BEHIND THE FRONT MONDAY. 12Z EC NOT AS
COLD AS THE 00Z RUN...THOUGH HAVE AGAIN SHADED AWAY FROM THE 50S AS
PRODUCED BY THE GFS. WILL PULL FOR THE WARMER GFS SOLUTION HOWEVER!
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* VARIABLE MVFR/VFR CIGS WITH PERIODIC LIGHT SNOW OR FLURRIES.
BMD
//DISCUSSION...UPDATED 00Z...
PATTERN DOES NOT CHANGE MUCH THROUGH THE FORECAST PERIOD WHICH IS
EXPECTED TO BE DOMINATED BY BREEZY NORTHERLY FLOW...VARIABLE
MVFR/VFR CIGS AND PERIODIC FLURRIES. DEEP AREA OF LOW PRESSURE OFF
THE MID ATLANTIC COAST THIS EVENING WILL KEEP BROAD CYCLONIC FLOW
WITH NORTH/NORTHWEST WINDS AND A COLD AIRMASS IN PLACE OVER NORTHERN
ILLINOIS AND NORTHWEST INDIANA. HIGH PRESSURE OVER THE CENTRAL
PLAINS WILL GRADUALLY BUILD EAST THROUGH THE PERIOD...ALLOWING WINDS
TO CONTINUE TO BACK SLIGHTLY TO THE NORTHWEST AND UNDERGO A GRADUAL
WEAKENING TREND. EXPECT STRATUS TO LINGER THROUGH THE FORECAST
PERIOD...WITH LIKELY DIURNALLY DRIVEN BASES THAT SHOULD DROP SOLIDLY
BACK INTO MVFR CATEGORY OVERNIGHT...THEN LIFT BACK TO HIGH END MVFR
OR LOWER VFR DURING THE DAY TUESDAY. LAKE EFFECT SNOW WILL LIKELY
CONTINUE THROUGH THE NIGHT BUT SHOULD GRADUALLY CONTINUE TO SHIFT
EAST AS WINDS BACK TO THE NORTHWEST. MORE WIDESPREAD FLURRIES AND
LIGHT SNOW ARE ALSO EXPECTED TO BE LARGELY DIURNALLY DRIVEN...WITH
LOW LEVEL LAPSE RATES INCREASING DURING THE DAY. AN UPPER LEVEL
DISTURBANCE DROPPING SOUTH ACROSS THE AREA LATE TUESDAY
MORNING/EARLY AFTERNOON MAY ALSO HELP THE SNOW POTENTIAL BUT OVERALL
FORCING WITH THIS WAVE IS WEAK AND THERE IS NO REINFORCING COLD AIR
NOTED. OVERALL EXPECT SNOW TO BE LIGHT ENOUGH THAT IT WILL NOT
IMPACT VSBY OR ACCUMULATE.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* MEDIUM TO HIGH CONFIDENCE IN CIG TRENDS.
* MEDIUM TO HIGH CONFIDENCE IN WIND SPEEDS...HIGH CONFIDENCE IN
DIRECTION.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...MVFR IMPROVING TO VFR.
THURSDAY...VFR.
FRIDAY...VFR.
SATURDAY...VFR.
SUNDAY...CHANCE OF RAIN/MFVR.
BMD
&&
.MARINE...
225 PM CDT
STRONG LOW PRESSURE OFF THE MID ATLANTIC COAST WILL MOVE EAST OUT
INTO THE ATLANTIC OCEAN WITH HIGH PRESSURE OVER THE PLAINS BUILDING
EAST INTO THE MISSISSIPPI VALLEY AND WESTERN GREAT LAKES. STRONG
NORTHERLY FETCH WILL KEEP WAVES UP FOR THE NEARSHORE THROUGH TUESDAY
OR TUESDAY NIGHT. FAIRLY LIGHT WINDS ARE EXPECTED WEDNESDAY THROUGH
FRIDAY AS HIGH PRESSURE SETS UP CAMP OVER THE REGION BEFORE SCOOTING
EAST OVER THE WEEKEND ALLOWING FOR SOUTHERLY WINDS TO DEVELOP.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 7 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
520 PM CDT SUN MAR 24 2013
.DISCUSSION...
305 PM CDT
SHORT TERM...SNOW STORM MOVING THROUGH THE MIDWEST TONIGHT INTO
MONDAY...
WINTER STORM WARNING/WINTER WEATHER ADVISORY HEADLINES CONTINUE
UNCHANGED. BUMPED SNOW AMOUNTS IN WARNING AREA SLIGHTLY...WITH
LOCALIZED 7-8 INCH NOT OUT OF THE QUESTION THERE.
MID-AFTERNOON FINDS SURFACE LOW PRESSURE OVER THE LOWER OHIO VALLEY
REGION...AND WELL-DEFINED CLOSED LOW ACROSS SOUTHEAST MISSOURI IN
GOES WATER VAPOR IMAGERY. NICE 4-5 MB PRESSURE RISE/FALL COUPLET
ASSOCIATED WITH THE SURFACE LOW...INDICATING SOME DEEPENING STILL
OCCURRING. CLASSIC COMMA SHAPE TO RADAR PRESENTATION IN REGIONAL
MOSAIC...WITH DEFORMATION BAND EXTENDING FROM CENTRAL MISSOURI
ACROSS CENTRAL IL AT 230 PM. PLENTY OF 3/4SM TO 1/4SM VISIBILITY
REPORTS IN MODERATE/HEAVY SNOW WITHIN THIS BAND PER METARS...WITH
HEAVIEST SNOW POISED TO AFFECT WFO CHICAGO WINTER STORM WARNING AREA
VERY SHORTLY. SEVERAL 6-8 INCH SNOWFALL REPORTS HAVE BEEN RECEIVED
FROM UPSTREAM AREAS IN MO/WESTERN IL. A FEW CLOUD-GROUND LIGHTNING
STRIKES CONTINUE TO BE NOTED AHEAD OF THE UPPER LOW...AS NEARBY AS
NORTH OF DECATUR WITHIN THE PAST 30 MINUTES.
OVERALL...LITTLE CHANGE TO FORECAST FROM EARLIER MORNING UPDATE.
SOME TWEAKS MADE WERE TO ADJUST QPF/SNOWFALL AMOUNTS ACROSS THE
ADVISORY/WARNING AREA...BASED ON SEVERAL RECENT MODEL RUNS DEPICTING
UPWARDS OF 0.50 INCHES OF LIQUID EQUIVALENT ACROSS THE SOUTHERN
PORTIONS OF OUR SOUTHERN TIER OF COUNTIES THROUGH THIS EVENING. HAVE
ALSO ADDED A MENTION OF ISOLATED THUNDER ACROSS THIS SAME AREA
THROUGH THE REMAINDER OF THE AFTERNOON HOURS...WITH MODEL DEPICTIONS
OF STEEP MID/UPPER LEVEL LAPSE RATES AND WEAK ELEVATED CAPE AS WELL
AS GRADIENT OF NEGATIVE SATURATED EPV ACROSS THE AREA INTO EARLY
EVENING. HAVE ENDED UP ADDING ABOUT AN INCH OVERALL TO OUR FAR SOUTH
AREA...WHILE DECREASING AMOUNTS FARTHER NORTH AND TRYING TO SHARPEN
UP THE GRADIENT FROM NOT MUCH SNOW TO SIGNIFICANT SNOW SOUTH OF
INTERSTATE 80 CORRIDOR. HEAVIEST SNOW EXPECTED TO OCCUR FROM THE
REMAINDER OF THE AFTERNOON HOURS INTO EARLY EVENING...BEFORE
TAPERING OFF TO LIGHT SNOW BY LATE EVENING/OVERNIGHT.
PERHAPS THE HARDEST PART OF FORECAST IS WITH THE LAKE EFFECT SNOW
POTENTIAL ACROSS NORTHEAST IL/NORTHWEST IND LATER TONIGHT AND
MONDAY. STRONG NORTHEAST WINDS WILL CONTINUE TO PROVIDE MOISTURE
CONVERGENCE AND FLUX OFF OF THE LAKE DURING THE PERIOD...THOUGH
FORECAST SOUNDINGS CONTINUE TO SHOW GENERALLY MARGINAL THERMODYNAMIC
PARAMETERS FOR STRONGER LAKE EFFECT SNOW. DELTA T VALUES GRADUALLY
INCREASE TO ONLY 13/14 DEG C THROUGH MONDAY AFTERNOON...WITH
INVERSION HEIGHTS SLOWLY RISING TO NEAR 7000 FT AGL LATE TONIGHT AND
MONDAY. THIS SHOULD SUPPORT INITIALLY WEAK MULTI-BAND LES INTO
EASTERN WI/NORTHEAST IL...THOUGH ACCUMULATION IS NOT EXPECTED TO BE
OF MUCH SIGNIFICANCE GIVEN WEAK THERMAL PROFILES.
AWAY FROM THE LAKE...STEEP LOW LEVEL LAPSE RATES IN BROAD AREA OF
COOL CYCLONIC FLOW WEST OF DEPARTING STORM WILL LIKELY SUPPORT
SCATTERED FLURRIES AND LIGHT SNOW SHOWERS MONDAY...BUT AGAIN WITH
LITTLE/NO ORGANIZED ACCUMULATION EXPECTED.
BLEND OF MOS TEMPS GENERALLY ACCEPTED TONIGHT/MONDAY...THOUGH WENT A
LITTLE ABOVE GUIDANCE IN A FEW SPOTS TONIGHT WITH PERSISTENT CLOUD
COVER.
RATZER
MEDIUM/LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY...
MONDAY NIGHT THROUGH TUESDAY...LAKE EFFECT SNOW SHOWERS WILL BE THE
MAIN CONCERN THROUGH TUESDAY. THE UPPER LOW WILL BE STEADILY MOVING
EASTWARD INTO THE ATLANTIC BUT A BROAD TROUGH/CYCLONIC FLOW WILL
EXPAND WELL TO THE WEST OF THE MAIN SYSTEM LEAVING THE LOCAL AREA
UNDER A NORTHWEST UPPER FLOW. WEAK UPPER RIDGING WILL BE IN PLACE
OVER THE FAR WESTERN U.S. BUT THIS LOOKS TO BE INTERRUPTED BY ENERGY
TRANSLATING THROUGH IT FROM THE EASTERN PACIFIC. HIGH PRESSURE WILL
BE SPRAWLED ACROSS THE MID SECTION OF NORTH AMERICA WHICH WILL KEEP
NORTHERLY LOW LEVEL FLOW IN PLACE LOCALLY. THIS WILL KEEP AIR
MARGINALLY COLD ENOUGH FOR LAKE EFFECT TO REMAIN IN PLACE MONDAY
NIGHT AND TUESDAY. LAKE TO H85 DELTA T/S GENERALLY RANGE FROM 11 TO
13C DURING THE PERIOD WITH INVERSION HEIGHTS HOVERING AROUND 5000 FT
WITH FLUCTUATIONS ABOVE AND BELOW THAT AT TIMES. THE FETCH REMAINS
FAVORABLE FOR ANY SNOW SHOWERS TO AFFECT FAR EASTERN COOK/WILL AND
LAKE INDIANA AND WESTERN PORTER MONDAY EVENING WITH A SLOW SHIFT
EASTWARD INTO THE OVERNIGHT HOURS. LATE MONDAY EVENING/MONDAY NIGHT
MAY BE THE PEAK TIME FOR LAKE EFFECT SNOW SHOWERS AS INVERSION
HEIGHTS ARE EXPECTED TO RISE TO 6000 OR POSSIBLY NEAR 7000 FT WITH
DELTA T/S AROUND 12C. WILL CARRY HIGHEST CHANCE POPS FOR THIS PERIOD
WITH LAKE COUNTY INDIANA AND PORTER COUNTY THE FOCUS AREAS. ASSUMING
SNOW SHOWERS DO BECOME SOMEWHAT ORGANIZED...SOME LIGHT ACCUMULATION
IS POSSIBLE...PROBABLY ON THE ORDER OF AN INCH OR MAYBE 2 BUT DO NOT
HAVE THE GREATEST CONFIDENCE IN AMOUNTS. WINDS GAIN ENOUGH OF A
WESTERLY COMPONENT TO GRADUALLY SHIFT THE FOCUS EASTWARD THROUGH THE
DAY ON TUESDAY. LAKE PARAMETERS BECOME LESS FAVORABLE THOUGH STILL
MARGINALLY SUPPORTIVE FOR ACTIVITY TUESDAY BUT SURFACE TEMPS WILL
WARM ABOVE FREEZING SO ACCUMULATION WILL BE TOUGH TO COME BY. AT
THIS POINT THE FOCUS WILL LIKELY BE ACROSS PORTER
COUNTY...ESPECIALLY EAST BUT WILL ONLY CARRY MID CHANCE POPS FOR
NOW. IT DOES APPEAR THAT WINDS WILL TURN NORTHWESTERLY ENOUGH TO
THEN PUSH ANY SNOW SHOWERS EAST OF PORTER COUNTY TUESDAY EVENING.
BEYOND THE LAKE EFFECT AREAS...A MIX OF SUN AND CLOUDS IS EXPECTED
TUESDAY WITH SOME EVIDENCE OF A WEAK SHORTWAVE DROPPING ACROSS THE
AREA. HIGHS WILL CONTINUE TO BE CHILLY IN THE UPPER 30S...BUT IF
ENOUGH SUNSHINE CAN PEAK THROUGH A FEW SPOTS COULD SEE 40...MAINLY
IN THE WEST.
WEDNESDAY THROUGH SUNDAY...THE OVERALL PATTERN REALLY WON/T CHANGE
MUCH ACROSS THE MIDWEST WITH NORTHWESTERLY FLOW CONTINUING ALOFT.
RIDGING WILL BUILD ACROSS THE ROCKIES THROUGH LATE WEEK WHICH WILL
HELP PUSH WARMER AIR ALOFT EASTWARD RESULTING IN MODERATING TEMPS
ACROSS THE LOCAL AREA. H85 TEMPS WARM TO AROUND -4C BY LATE THURSDAY
BUT SURFACE HIGH PRESSURE WILL BE RIGHT OVERHEAD. LAKE BREEZE
DEVELOPMENT APPEARS LIKELY WEDNESDAY...AND ESPECIALLY THURSDAY SO
AREAS NEAR THE LAKE WILL BE HELD INTO THE UPPER 30S TO AROUND 40 FOR
HIGH WEDNESDAY AND THURSDAY WHILE THE REST OF THE AREA WARMS TO
AROUND 40 WEDNESDAY AND INTO THE MID 40S...IF NOT A LITTLE
HIGHER...THURSDAY. AREAS WITH THE GREATEST SNOW COVER FROM
TODAY/TONIGHT WILL LIKELY BE ON THE LOWER END OF THOSE RANGES BUT
THIS WILL BECOME MORE CLEAR ONCE EXTENT/AMOUNT OF SNOW COVER IS
KNOWN IN THE MORNING. AT THIS POINT...THE TRACK OF ANY SHORTWAVES
LOOKS TO REMAIN SOUTHWEST OF THE AREA SO DRY WEATHER IS EXPECTED.
RIDGING CONTINUES TO EXPAND EASTWARD THROUGH SATURDAY BRINGING
FURTHER BUT STILL MODEST WARM ADVECTION INTO THE AREA ALOFT SO THE
WARMING TREND WILL LIKELY CONTINUE. H85 TEMPS WILL BE CLOSE TO -2C
SATURDAY AND A SOUTHWESTERLY WIND WILL HAVE SET UP BEHIND HIGH
PRESSURE DEPARTING TO THE SOUTHEAST. THIS MAY PUSH TEMPS AT LEAST
CLOSE TO IF NOT ABOVE NORMAL. A CUTOFF UPPER LOW WILL BE IN PLACE
OFF THE CALIFORNIA COAST BY THIS TIME WITH ANOTHER TROUGH OVER
ALASKA. SHORTWAVE ENERGY LOOKS TO EJECT FROM THE ALASKA TROUGH AND
TRACK SOUTHEAST THROUGH THE CONTINUED NORTHWESTERLY UPPER FLOW AND
AFFECT THE AREA SATURDAY NIGHT OR SUNDAY WITH THE ECMWF AND GFS
ACTUALLY IN VERY GOOD AGREEMENT WITH THIS. DETAILS OF THIS MAY
CHANGE BUT A SYSTEM SUCH AS THIS MAKES SENSE GIVEN THE MORE ACTIVE
FLOW OVER THE PACIFIC AND THE EASTWARD ADVANCEMENT OF THE UPPER
RIDGE PUSHING THE STORM TRACK FURTHER NORTH AND EAST. WILL CARRY
CHANCE POPS FOR SATURDAY NIGHT AND SUNDAY FOR NOW.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* SNOW DEVELOPING OVER NORTHEASTERN IL THIS EVENING AND POTENTIAL
IMPACTS DUE TO VSBY/ACCUMULATIONS.
* GUSTY NORTHEAST WINDS AROUND 30 KT GRADUALLY BACKING TO NORTH.
* LAKE EFFECT SNOW SHOWERS DEVELOPING THIS EVENING AND OVERNIGHT.
BMD/IZZI
//DISCUSSION...UPDATED 22Z...
CLOSELY WATCHING DEVELOPING AREA OF SNOW OVER NORTH CENTRAL
ILLINOIS...WITH SIGNS OF THIS BAND ATTEMPTING TO DEVELOP EASTWARD
TOWARD CHICAGO IN SOME OF THE HIGHER RADAR ELEVATION ANGLES. AN
ACARS SOUNDING OUT OF MDW AT 2106Z INDICATED ABOUT A 4500FT DEEP
LAYER OF SUBSATURATED AIR FROM 045-090...BUT AIR WASNT ESPECIALLY
DRY SO CONTINUED VIRGA INTO THIS LAYER COULD RESULT IN A RATHER
QUICK SATURATION AND EASTWARD DEVELOPMENT OF THE SNOW BAND. THE
DEVELOPING BAND OF SNOW APPEARS TO BE LIFTING NORTH AND
DEVELOPMENT COULD STILL BE NORTH OF ORD BY THE TIME IT FILLS
IN...THOUGH SOME INCREASE IN ECHOS ALOFT ALSO NOTED OVER WILL
COUNTY. PLAN TO PUSH THE TIMING OF THE TEMPO UP ABOUT AN HOUR AND
THE PREVAILING FLURRIES UP A HALF HOUR...BUT OTHERWISE WILL RIDE
WITH GOING FORECAST FOR NOW AND CLOSELY MONITOR RADAR/OBSERVATION
TRENDS THE NEXT COUPLE HOURS.
IZZI
UPDATED 20Z...
EARLIER BAND OF SNOW MENTIONED OVER NORTH CENTRAL ILLINOIS FELL
APART QUICKER THAN ORIGINALLY ANTICIPATED RESULTING IN SNOW BEING
PUSHED BACK SEVERAL HOURS THIS AFTERNOON IN THE TAFS. ANOTHER
BAND OF SNOW LIFTING NORTH INTO THE I-80 CORRIDOR WILL LIKELY
SUFFER A SIMILAR FATE AS IT PUSHES INTO DRY AIR AND OVERALL
FORCING DIMINISHES. LATEST RAP/HRRR HOURLY GUIDANCE STILL TRY TO
BRING SOME PRECIP INTO THE CHICAGO TERMINALS EARLY THIS
EVENING...WITH HRRR STILL HINTING AT LAKE ENHANCEMENT.
PREVIOUS 18Z DISCUSSION...
TRICKY FORECAST THIS AFTERNOON DEALING WITH WHAT WILL LIKELY BE A
SHARP CUTOFF OF HEAVY SNOW ACCUMULATIONS WHICH ARE EXPECTED TO BE
SOUTH OF INTERSTATE 80 TO A DUSTING OR LESS ACROSS FAR NORTHERN
ILLINOIS. AFTERNOON RADAR IMAGERY SHOWS AN BATCH OF MODERATE SNOW
MOVING INTO NORTH CENTRAL ILLINOIS ON ITS WAY TOWARDS THE CHICAGO
TERMINALS 20-21Z. THIS AREA IS PRODUCING SNOW DROPPING VSBY TO
LESS THAN A MILE CURRENTLY...HOWEVER EXPECT THIS TO STRUGGLE TO
HOLD TOGETHER AS IT LIFTS INTO DRIER AIR AND AS OVERALL FORCING
DIMINISHES OVER NORTHERN ILLINOIS. LATEST SHORT TERM HOURLY
GUIDANCE AS WELL AS NAM AND SEVERAL HI-RES WRF RUNS ARE ALL IN
GOOD AGREEMENT KEEPING HEAVIEST QPF AXIS ALONG AND SOUTH OF
INTERSTATE 80. MANY OF THESE MODELS KEEP ORD/MDW DRY ALTOGETHER
WHILE OTHERS BRING UP A FEW HUNDREDTHS OF LIQUID EQUIVALENT
PRECIP. GIVEN RADAR TRENDS CANT RULE OUT A LIGHT DUSTING OF SNOW
AT THE TERMINALS THIS AFTERNOON...NOR A BRIEF DROP TO IFR
VSBY...HOWEVER THINK THIS TO BE UNLIKELY AS OF TAF ISSUANCE.
BREEZY NORTHWESTERLY WINDS WILL CONTINUE THROUGH THE REST OF THE
DAY INTO TONIGHT...LIKELY PICKING UP TO AROUND 30 KT THIS
AFTERNOON AND TAPERING SLIGHTLY LATE IN THE EVENING.
FOCUS WILL BE ON LAKE ENHANCED OR LAKE EFFECT SNOW THIS EVENING.
WIND TURNS TO NNE AROUND 00Z THIS EVENING WITH SHALLOW LAKE INDUCED
INSTABILITY POTENTIALLY ENHANCING OR DEVELOPING NEW SHOWERS.
EQUILIBRIUM LEVELS ARE MEAGER INITIALLY...BUT GRADUALLY DEEPEN TO
AROUND 070 BY 10Z AS THE WINDS VERY SLOWLY CONTINUE TO BACK TO THE
NORTH. CAN SEE THE LAKE EFFECT SIGNATURE IN SOME OF THE RAW GUIDANCE
OUTPUT INCLUDING THE GFS/ECMWF AND GEM...BUT PINNING DOWN THE
DETAILS IS HARD SINCE NONE OF THE HIGHER RES GUIDANCE SEEMS TO HINT
AT IT...EXCEPT FOR THE HRRR. THERE IS POTENTIAL FOR SOME LIGHT
ACCUMULATIONS AND IF A BAND DOES GET GOING COULDNT RULE OUT A QUICK
INCH IN SOME PLACES...BUT THINK THAT GIVEN THE MARGINAL THERMAL
CONDITIONS THIS MAY AMOUNT TO LITTLE MORE THAN VERY LIGHT SNOW OR
FLURRIES.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN SNOW THIS EVENING
* LOW CONFIDENCE IN TIMING/IMPACTS OF LAKE EFFECT SNOW THIS EVENING.
* MMEDIUM CONFIDENCE IN CIG TRENDS.
* HIGH CONFIDENCE IN WIND TRENDS.
IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY...MVFR CIGS LIKELY. CHANCE OF LAKE EFFECT SNOW SHOWERS.
TUESDAY...MVFR CIGS.
WEDNESDAY...VFR.
THURSDAY AND FRIDAY...VFR.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...MVFR CIGS LIKELY. CHANCE OF LAKE EFFECT SNOW
SHOWERS.
TUESDAY...MVFR CIGS.
WEDNESDAY THROUGH SATURDAY...VFR.
TRS
&&
.MARINE...
153 PM CDT
THE MAIN WEATHER CONCERNS THROUGH THE PERIOD CONTINUE TO FOCUS ON
THE SIGNIFICANT STORM SYSTEM AFFECTING THE LAKE TONIGHT THROUGH
MONDAY. WINDS HAVE BEGAN INCREASING UP TO 25 TO 30 KT OUT OF THE
EAST-NORTHEAST ALREADY IN RESPONSE TO AN AREA OF DEEPENING LOW
PRESSURE MOVING EAST-NORTHEASTWARD ACROSS WESTERN KENTUCKY EARLY
THIS AFTERNOON. THIS LOW WILL CONTINUE ACROSS THE OHIO VALLEY
TONIGHT...THEN MERGE WITH A NEW LOW MOVING UP THE CENTRAL ATLANTIC
COAST LATER MONDAY. IT APPEARS THE WINDS WILL CONTINUE TO INCREASE
OVER THE NEXT SEVERAL HOURS...WITH GALES OF 35 TO 40 KT BECOMING
LIKELY BY LATE AFTERNOON ACROSS THE FAR SOUTHERN END OF LAKE
MICHIGAN. LATE TONIGHT AND INTO MONDAY THE FLOW WILL TURN MORE
NORTHERLY AS THE LOW MOVES ACROSS THE OHIO VALLEY. IT APPEARS SOME
GALES COULD PERSIST INTO THE EARLY MORNING HOURS...BEFORE EASING
SLIGHTLY TO 30 KT. I UPGRADED THE SMALL CRAFT ADVISORY TO A GALE
WARNING FOR THE ILLINOIS AND INDIANA SHORES...AND I INCLUDED THE
OPEN WATERS OF FAR SOUTHERN LAKE MICHIGAN FOR LATE THIS AFTERNOON
THROUGH MONDAY MORNING.
THE LONG NORTHERLY FETCH WILL RESULT IN SOME VERY HIGH WAVES ACROSS
THE SOUTHERN END OF THE LAKE...INCLUDING THE NEAR SHORE WATERS.
THESE LARGE WAVES WILL LIKELY PROLONG HAZARDOUS CONDITIONS FOR SMALL
CRAFT FOR BOTH THE ILLINOIS AND THE INDIANA NEAR SHORE WATERS BEYOND
THE GALE PERIOD. HOWEVER...CONDITIONS WILL BEGIN TO IMPROVE BY MID
WEEK AS A SURFACE RIDGE OF HIGH PRESSURE APPROACHES THE WESTERN
LAKES. THIS WILL LIKELY RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS INTO THE END OF THE WEEK.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ033-ILZ039 UNTIL 7 AM MONDAY.
WINTER WEATHER ADVISORY...ILZ023-ILZ032 UNTIL 7 AM MONDAY.
IN...WINTER WEATHER ADVISORY...INZ010-INZ011 UNTIL 7 AM MONDAY.
WINTER STORM WARNING...INZ019 UNTIL 7 AM MONDAY.
LM...GALE WARNING...LMZ080-LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ876-LMZ878 UNTIL 10 AM MONDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...10 AM MONDAY TO 7 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
307 PM CDT SUN MAR 24 2013
.DISCUSSION...
305 PM CDT
SHORT TERM...SNOW STORM MOVING THROUGH THE MIDWEST TONIGHT INTO
MONDAY...
WINTER STORM WARNING/WINTER WEATHER ADVISORY HEADLINES CONTINUE
UNCHANGED. BUMPED SNOW AMOUNTS IN WARNING AREA SLIGHTLY...WITH
LOCALIZED 7-8 INCH NOT OUT OF THE QUESTION THERE.
MID-AFTERNOON FINDS SURFACE LOW PRESSURE OVER THE LOWER OHIO VALLEY
REGION...AND WELL-DEFINED CLOSED LOW ACROSS SOUTHEAST MISSOURI IN
GOES WATER VAPOR IMAGERY. NICE 4-5 MB PRESSURE RISE/FALL COUPLET
ASSOCIATED WITH THE SURFACE LOW...INDICATING SOME DEEPENING STILL
OCCURRING. CLASSIC COMMA SHAPE TO RADAR PRESENTATION IN REGIONAL
MOSAIC...WITH DEFORMATION BAND EXTENDING FROM CENTRAL MISSOURI
ACROSS CENTRAL IL AT 230 PM. PLENTY OF 3/4SM TO 1/4SM VISIBILITY
REPORTS IN MODERATE/HEAVY SNOW WITHIN THIS BAND PER METARS...WITH
HEAVIEST SNOW POISED TO AFFECT WFO CHICAGO WINTER STORM WARNING AREA
VERY SHORTLY. SEVERAL 6-8 INCH SNOWFALL REPORTS HAVE BEEN RECEIVED
FROM UPSTREAM AREAS IN MO/WESTERN IL. A FEW CLOUD-GROUND LIGHTNING
STRIKES CONTINUE TO BE NOTED AHEAD OF THE UPPER LOW...AS NEARBY AS
NORTH OF DECATUR WITHIN THE PAST 30 MINUTES.
OVERALL...LITTLE CHANGE TO FORECAST FROM EARLIER MORNING UPDATE.
SOME TWEAKS MADE WERE TO ADJUST QPF/SNOWFALL AMOUNTS ACROSS THE
ADVISORY/WARNING AREA...BASED ON SEVERAL RECENT MODEL RUNS DEPICTING
UPWARDS OF 0.50 INCHES OF LIQUID EQUIVALENT ACROSS THE SOUTHERN
PORTIONS OF OUR SOUTHERN TIER OF COUNTIES THROUGH THIS EVENING. HAVE
ALSO ADDED A MENTION OF ISOLATED THUNDER ACROSS THIS SAME AREA
THROUGH THE REMAINDER OF THE AFTERNOON HOURS...WITH MODEL DEPICTIONS
OF STEEP MID/UPPER LEVEL LAPSE RATES AND WEAK ELEVATED CAPE AS WELL
AS GRADIENT OF NEGATIVE SATURATED EPV ACROSS THE AREA INTO EARLY
EVENING. HAVE ENDED UP ADDING ABOUT AN INCH OVERALL TO OUR FAR SOUTH
AREA...WHILE DECREASING AMOUNTS FARTHER NORTH AND TRYING TO SHARPEN
UP THE GRADIENT FROM NOT MUCH SNOW TO SIGNIFICANT SNOW SOUTH OF
INTERSTATE 80 CORRIDOR. HEAVIEST SNOW EXPECTED TO OCCUR FROM THE
REMAINDER OF THE AFTERNOON HOURS INTO EARLY EVENING...BEFORE
TAPERING OFF TO LIGHT SNOW BY LATE EVENING/OVERNIGHT.
PERHAPS THE HARDEST PART OF FORECAST IS WITH THE LAKE EFFECT SNOW
POTENTIAL ACROSS NORTHEAST IL/NORTHWEST IND LATER TONIGHT AND
MONDAY. STRONG NORTHEAST WINDS WILL CONTINUE TO PROVIDE MOISTURE
CONVERGENCE AND FLUX OFF OF THE LAKE DURING THE PERIOD...THOUGH
FORECAST SOUNDINGS CONTINUE TO SHOW GENERALLY MARGINAL THERMODYNAMIC
PARAMETERS FOR STRONGER LAKE EFFECT SNOW. DELTA T VALUES GRADUALLY
INCREASE TO ONLY 13/14 DEG C THROUGH MONDAY AFTERNOON...WITH
INVERSION HEIGHTS SLOWLY RISING TO NEAR 7000 FT AGL LATE TONIGHT AND
MONDAY. THIS SHOULD SUPPORT INITIALLY WEAK MULTI-BAND LES INTO
EASTERN WI/NORTHEAST IL...THOUGH ACCUMULATION IS NOT EXPECTED TO BE
OF MUCH SIGNIFICANCE GIVEN WEAK THERMAL PROFILES.
AWAY FROM THE LAKE...STEEP LOW LEVEL LAPSE RATES IN BROAD AREA OF
COOL CYCLONIC FLOW WEST OF DEPARTING STORM WILL LIKELY SUPPORT
SCATTERED FLURRIES AND LIGHT SNOW SHOWERS MONDAY...BUT AGAIN WITH
LITTLE/NO ORGANIZED ACCUMULATION EXPECTED.
BLEND OF MOS TEMPS GENERALLY ACCEPTED TONIGHT/MONDAY...THOUGH WENT A
LITTLE ABOVE GUIDANCE IN A FEW SPOTS TONIGHT WITH PERSISTENT CLOUD
COVER.
RATZER
MEDIUM/LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY...
MONDAY NIGHT THROUGH TUESDAY...LAKE EFFECT SNOW SHOWERS WILL BE THE
MAIN CONCERN THROUGH TUESDAY. THE UPPER LOW WILL BE STEADILY MOVING
EASTWARD INTO THE ATLANTIC BUT A BROAD TROUGH/CYCLONIC FLOW WILL
EXPAND WELL TO THE WEST OF THE MAIN SYSTEM LEAVING THE LOCAL AREA
UNDER A NORTHWEST UPPER FLOW. WEAK UPPER RIDGING WILL BE IN PLACE
OVER THE FAR WESTERN U.S. BUT THIS LOOKS TO BE INTERRUPTED BY ENERGY
TRANSLATING THROUGH IT FROM THE EASTERN PACIFIC. HIGH PRESSURE WILL
BE SPRAWLED ACROSS THE MID SECTION OF NORTH AMERICA WHICH WILL KEEP
NORTHERLY LOW LEVEL FLOW IN PLACE LOCALLY. THIS WILL KEEP AIR
MARGINALLY COLD ENOUGH FOR LAKE EFFECT TO REMAIN IN PLACE MONDAY
NIGHT AND TUESDAY. LAKE TO H85 DELTA T/S GENERALLY RANGE FROM 11 TO
13C DURING THE PERIOD WITH INVERSION HEIGHTS HOVERING AROUND 5000 FT
WITH FLUCTUATIONS ABOVE AND BELOW THAT AT TIMES. THE FETCH REMAINS
FAVORABLE FOR ANY SNOW SHOWERS TO AFFECT FAR EASTERN COOK/WILL AND
LAKE INDIANA AND WESTERN PORTER MONDAY EVENING WITH A SLOW SHIFT
EASTWARD INTO THE OVERNIGHT HOURS. LATE MONDAY EVENING/MONDAY NIGHT
MAY BE THE PEAK TIME FOR LAKE EFFECT SNOW SHOWERS AS INVERSION
HEIGHTS ARE EXPECTED TO RISE TO 6000 OR POSSIBLY NEAR 7000 FT WITH
DELTA T/S AROUND 12C. WILL CARRY HIGHEST CHANCE POPS FOR THIS PERIOD
WITH LAKE COUNTY INDIANA AND PORTER COUNTY THE FOCUS AREAS. ASSUMING
SNOW SHOWERS DO BECOME SOMEWHAT ORGANIZED...SOME LIGHT ACCUMULATION
IS POSSIBLE...PROBABLY ON THE ORDER OF AN INCH OR MAYBE 2 BUT DO NOT
HAVE THE GREATEST CONFIDENCE IN AMOUNTS. WINDS GAIN ENOUGH OF A
WESTERLY COMPONENT TO GRADUALLY SHIFT THE FOCUS EASTWARD THROUGH THE
DAY ON TUESDAY. LAKE PARAMETERS BECOME LESS FAVORABLE THOUGH STILL
MARGINALLY SUPPORTIVE FOR ACTIVITY TUESDAY BUT SURFACE TEMPS WILL
WARM ABOVE FREEZING SO ACCUMULATION WILL BE TOUGH TO COME BY. AT
THIS POINT THE FOCUS WILL LIKELY BE ACROSS PORTER
COUNTY...ESPECIALLY EAST BUT WILL ONLY CARRY MID CHANCE POPS FOR
NOW. IT DOES APPEAR THAT WINDS WILL TURN NORTHWESTERLY ENOUGH TO
THEN PUSH ANY SNOW SHOWERS EAST OF PORTER COUNTY TUESDAY EVENING.
BEYOND THE LAKE EFFECT AREAS...A MIX OF SUN AND CLOUDS IS EXPECTED
TUESDAY WITH SOME EVIDENCE OF A WEAK SHORTWAVE DROPPING ACROSS THE
AREA. HIGHS WILL CONTINUE TO BE CHILLY IN THE UPPER 30S...BUT IF
ENOUGH SUNSHINE CAN PEAK THROUGH A FEW SPOTS COULD SEE 40...MAINLY
IN THE WEST.
WEDNESDAY THROUGH SUNDAY...THE OVERALL PATTERN REALLY WON/T CHANGE
MUCH ACROSS THE MIDWEST WITH NORTHWESTERLY FLOW CONTINUING ALOFT.
RIDGING WILL BUILD ACROSS THE ROCKIES THROUGH LATE WEEK WHICH WILL
HELP PUSH WARMER AIR ALOFT EASTWARD RESULTING IN MODERATING TEMPS
ACROSS THE LOCAL AREA. H85 TEMPS WARM TO AROUND -4C BY LATE THURSDAY
BUT SURFACE HIGH PRESSURE WILL BE RIGHT OVERHEAD. LAKE BREEZE
DEVELOPMENT APPEARS LIKELY WEDNESDAY...AND ESPECIALLY THURSDAY SO
AREAS NEAR THE LAKE WILL BE HELD INTO THE UPPER 30S TO AROUND 40 FOR
HIGH WEDNESDAY AND THURSDAY WHILE THE REST OF THE AREA WARMS TO
AROUND 40 WEDNESDAY AND INTO THE MID 40S...IF NOT A LITTLE
HIGHER...THURSDAY. AREAS WITH THE GREATEST SNOW COVER FROM
TODAY/TONIGHT WILL LIKELY BE ON THE LOWER END OF THOSE RANGES BUT
THIS WILL BECOME MORE CLEAR ONCE EXTENT/AMOUNT OF SNOW COVER IS
KNOWN IN THE MORNING. AT THIS POINT...THE TRACK OF ANY SHORTWAVES
LOOKS TO REMAIN SOUTHWEST OF THE AREA SO DRY WEATHER IS EXPECTED.
RIDGING CONTINUES TO EXPAND EASTWARD THROUGH SATURDAY BRINGING
FURTHER BUT STILL MODEST WARM ADVECTION INTO THE AREA ALOFT SO THE
WARMING TREND WILL LIKELY CONTINUE. H85 TEMPS WILL BE CLOSE TO -2C
SATURDAY AND A SOUTHWESTERLY WIND WILL HAVE SET UP BEHIND HIGH
PRESSURE DEPARTING TO THE SOUTHEAST. THIS MAY PUSH TEMPS AT LEAST
CLOSE TO IF NOT ABOVE NORMAL. A CUTOFF UPPER LOW WILL BE IN PLACE
OFF THE CALIFORNIA COAST BY THIS TIME WITH ANOTHER TROUGH OVER
ALASKA. SHORTWAVE ENERGY LOOKS TO EJECT FROM THE ALASKA TROUGH AND
TRACK SOUTHEAST THROUGH THE CONTINUED NORTHWESTERLY UPPER FLOW AND
AFFECT THE AREA SATURDAY NIGHT OR SUNDAY WITH THE ECMWF AND GFS
ACTUALLY IN VERY GOOD AGREEMENT WITH THIS. DETAILS OF THIS MAY
CHANGE BUT A SYSTEM SUCH AS THIS MAKES SENSE GIVEN THE MORE ACTIVE
FLOW OVER THE PACIFIC AND THE EASTWARD ADVANCEMENT OF THE UPPER
RIDGE PUSHING THE STORM TRACK FURTHER NORTH AND EAST. WILL CARRY
CHANCE POPS FOR SATURDAY NIGHT AND SUNDAY FOR NOW.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* SNOW OVERSPREADING NORTHEASTERN ILLINOIS THIS AFTERNOON...AND
POTENTIAL IMPACTS DUE TO VSBY/ACCUMULATIONS.
* GUSTY NORTHEAST WINDS AROUND 30 KT GRADUALLY BACKING TO NORTH.
* LAKE EFFECT SNOW SHOWERS DEVELOPING THIS EVENING AND OVERNIGHT.
BMD
//DISCUSSION...UPDATED 20Z...
EARLIER BAND OF SNOW MENTIONED OVER NORTH CENTRAL ILLINOIS FELL
APART QUICKER THAN ORIGINALLY ANTICIPATED RESULTING IN SNOW BEING
PUSHED BACK SEVERAL HOURS THIS AFTERNOON IN THE TAFS. ANOTHER
BAND OF SNOW LIFTING NORTH INTO THE I-80 CORRIDOR WILL LIKELY
SUFFER A SIMILAR FATE AS IT PUSHES INTO DRY AIR AND OVERALL
FORCING DIMINISHES. LATEST RAP/HRRR HOURLY GUIDANCE STILL TRY TO
BRING SOME PRECIP INTO THE CHICAGO TERMINALS EARLY THIS
EVENING...WITH HRRR STILL HINTING AT LAKE ENHANCEMENT.
PREVIOUS 18Z DISCUSSION...
TRICKY FORECAST THIS AFTERNOON DEALING WITH WHAT WILL LIKELY BE A
SHARP CUTOFF OF HEAVY SNOW ACCUMULATIONS WHICH ARE EXPECTED TO BE
SOUTH OF INTERSTATE 80 TO A DUSTING OR LESS ACROSS FAR NORTHERN
ILLINOIS. AFTERNOON RADAR IMAGERY SHOWS AN BATCH OF MODERATE SNOW
MOVING INTO NORTH CENTRAL ILLINOIS ON ITS WAY TOWARDS THE CHICAGO
TERMINALS 20-21Z. THIS AREA IS PRODUCING SNOW DROPPING VSBY TO
LESS THAN A MILE CURRENTLY...HOWEVER EXPECT THIS TO STRUGGLE TO
HOLD TOGETHER AS IT LIFTS INTO DRIER AIR AND AS OVERALL FORCING
DIMINISHES OVER NORTHERN ILLINOIS. LATEST SHORT TERM HOURLY
GUIDANCE AS WELL AS NAM AND SEVERAL HI-RES WRF RUNS ARE ALL IN
GOOD AGREEMENT KEEPING HEAVIEST QPF AXIS ALONG AND SOUTH OF
INTERSTATE 80. MANY OF THESE MODELS KEEP ORD/MDW DRY ALTOGETHER
WHILE OTHERS BRING UP A FEW HUNDREDTHS OF LIQUID EQUIVALENT
PRECIP. GIVEN RADAR TRENDS CANT RULE OUT A LIGHT DUSTING OF SNOW
AT THE TERMINALS THIS AFTERNOON...NOR A BRIEF DROP TO IFR
VSBY...HOWEVER THINK THIS TO BE UNLIKELY AS OF TAF ISSUANCE.
BREEZY NORTHWESTERLY WINDS WILL CONTINUE THROUGH THE REST OF THE
DAY INTO TONIGHT...LIKELY PICKING UP TO AROUND 30 KT THIS
AFTERNOON AND TAPERING SLIGHTLY LATE IN THE EVENING.
FOCUS WILL BE ON LAKE ENHANCED OR LAKE EFFECT SNOW THIS EVENING.
WIND TURNS TO NNE AROUND 00Z THIS EVENING WITH SHALLOW LAKE INDUCED
INSTABILITY POTENTIALLY ENHANCING OR DEVELOPING NEW SHOWERS.
EQUILIBRIUM LEVELS ARE MEAGER INITIALLY...BUT GRADUALLY DEEPEN TO
AROUND 070 BY 10Z AS THE WINDS VERY SLOWLY CONTINUE TO BACK TO THE
NORTH. CAN SEE THE LAKE EFFECT SIGNATURE IN SOME OF THE RAW GUIDANCE
OUTPUT INCLUDING THE GFS/ECMWF AND GEM...BUT PINNING DOWN THE
DETAILS IS HARD SINCE NONE OF THE HIGHER RES GUIDANCE SEEMS TO HINT
AT IT...EXCEPT FOR THE HRRR. THERE IS POTENTIAL FOR SOME LIGHT
ACCUMULATIONS AND IF A BAND DOES GET GOING COULDNT RULE OUT A QUICK
INCH IN SOME PLACES...BUT THINK THAT GIVEN THE MARGINAL THERMAL
CONDITIONS THIS MAY AMOUNT TO LITTLE MORE THAN VERY LIGHT SNOW OR
FLURRIES.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* DECREASING CONFIDENCE THAT SNOW WILL IMPACT THE TERMINALS
RESULTING IN REDUCED VSBY OR ANY ACCUMULATION.
* LOW CONFIDENCE IN TIMING/IMPACTS OF LAKE EFFECT SNOW THIS EVENING.
* HIGH CONFIDENCE IN CIG TRENDS.
* HIGH CONFIDENCE IN WIND TRENDS.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY...MVFR CIGS LIKELY. CHANCE OF LAKE EFFECT SNOW SHOWERS.
TUESDAY...MVFR CIGS.
WEDNESDAY...VFR.
THURSDAY AND FRIDAY...VFR.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...MVFR CIGS LIKELY. CHANCE OF LAKE EFFECT SNOW
SHOWERS.
TUESDAY...MVFR CIGS.
WEDNESDAY THROUGH SATURDAY...VFR.
TRS
&&
.MARINE...
153 PM CDT
THE MAIN WEATHER CONCERNS THROUGH THE PERIOD CONTINUE TO FOCUS ON
THE SIGNIFICANT STORM SYSTEM AFFECTING THE LAKE TONIGHT THROUGH
MONDAY. WINDS HAVE BEGAN INCREASING UP TO 25 TO 30 KT OUT OF THE
EAST-NORTHEAST ALREADY IN RESPONSE TO AN AREA OF DEEPENING LOW
PRESSURE MOVING EAST-NORTHEASTWARD ACROSS WESTERN KENTUCKY EARLY
THIS AFTERNOON. THIS LOW WILL CONTINUE ACROSS THE OHIO VALLEY
TONIGHT...THEN MERGE WITH A NEW LOW MOVING UP THE CENTRAL ATLANTIC
COAST LATER MONDAY. IT APPEARS THE WINDS WILL CONTINUE TO INCREASE
OVER THE NEXT SEVERAL HOURS...WITH GALES OF 35 TO 40 KT BECOMING
LIKELY BY LATE AFTERNOON ACROSS THE FAR SOUTHERN END OF LAKE
MICHIGAN. LATE TONIGHT AND INTO MONDAY THE FLOW WILL TURN MORE
NORTHERLY AS THE LOW MOVES ACROSS THE OHIO VALLEY. IT APPEARS SOME
GALES COULD PERSIST INTO THE EARLY MORNING HOURS...BEFORE EASING
SLIGHTLY TO 30 KT. I UPGRADED THE SMALL CRAFT ADVISORY TO A GALE
WARNING FOR THE ILLINOIS AND INDIANA SHORES...AND I INCLUDED THE
OPEN WATERS OF FAR SOUTHERN LAKE MICHIGAN FOR LATE THIS AFTERNOON
THROUGH MONDAY MORNING.
THE LONG NORTHERLY FETCH WILL RESULT IN SOME VERY HIGH WAVES ACROSS
THE SOUTHERN END OF THE LAKE...INCLUDING THE NEAR SHORE WATERS.
THESE LARGE WAVES WILL LIKELY PROLONG HAZARDOUS CONDITIONS FOR SMALL
CRAFT FOR BOTH THE ILLINOIS AND THE INDIANA NEAR SHORE WATERS BEYOND
THE GALE PERIOD. HOWEVER...CONDITIONS WILL BEGIN TO IMPROVE BY MID
WEEK AS A SURFACE RIDGE OF HIGH PRESSURE APPROACHES THE WESTERN
LAKES. THIS WILL LIKELY RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS INTO THE END OF THE WEEK.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ033-ILZ039 UNTIL 7 AM MONDAY.
WINTER WEATHER ADVISORY...ILZ023-ILZ032 UNTIL 7 AM MONDAY.
IN...WINTER WEATHER ADVISORY...INZ010-INZ011 UNTIL 7 AM MONDAY.
WINTER STORM WARNING...INZ019 UNTIL 7 AM MONDAY.
LM...GALE WARNING...LMZ080-LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ876-LMZ878 UNTIL 10 AM MONDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 5 PM SUNDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...10 AM MONDAY TO 7 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
247 PM CDT SUN MAR 24 2013
.DISCUSSION...
1027 AM CDT
FOR MORNING UPDATE...
HAVE MADE A FEW TWEAKS TO GOING FORECAST...LARGELY TO LOWER POPS AND
QPF/SNOWFALL AMOUNTS A BIT ACROSS THE NORTHERN THIRD/HALF OF THE
CWA...AND TO ADD DETAIL OF LULL IN PRECIP DURING THE MORNING ACROSS
THE SOUTHEAST. WARNING/ADVISORY HEADLINES WILL CONTINUE AS IS...
WITH HIGH-RES GUIDANCE STILL IN GOOD AGREEMENT IN DEPICTING THE
POTENTIAL FOR ACCUMULATING SNOW ACROSS THE SOUTHERN COUPLE OF TIERS
OF CWA COUNTIES LATER THIS AFTERNOON/EARLY EVENING.
MORNING UPPER AIR/WATER VAPOR DATA DEPICT STRONG/COMPACT CLOSED
UPPER LOW OVER SOUTHERN MO/NORTHERN ARKANSAS...WITH SURFACE LOW
ALONG THE MISSISSIPPI RIVER SOUTH OF KPAH. A WEAKER LEAD SHORT WAVE
WAS LIFTING NORTHEAST ACROSS IL/IN/WI...WITH AN ATTENDANT REGION OF
MAINLY LIGHT SNOW/FLURRIES...WHILE THE MAIN SHOW OF MODERATE-HEAVY
SNOW AND THUNDERSNOW WAS LOCATED CLOSER TO THE UPPER LOW ACROSS
MO/WESTERN IL. AREA BETWEEN ADVANCING PRECIP FROM UPPER LOW AND
WEAKER LEAD VORT HAD SHOWN A DECREASE IN PRECIP COVERAGE PER
REGIONAL RADAR MOSAIC...SO HAVE ADJUSTED POPS DOWNWARD ACROSS
SOUTHERN COUNTIES WHERE LITTLE/NO ACCUMULATING PRECIP IS EXPECTED
UNTIL MIDDAY AND BEYOND.
GUIDANCE CONTINUES TO DEEPEN UPPER LOW/SURFACE LOW AS IT MOVES EAST
ACROSS THE LOWER OHIO VALLEY THIS AFTERNOON/EARLY THIS EVENING...
WITH TRENDS IN GUIDANCE CONTINUING TO FOCUS PRECIP ALONG FAR
SOUTHERN CWA AND AREAS DOWNSTATE...WHILE DECREASING QPF ACROSS OUR
NORTHERN COUNTIES. THUS HAVE ADJUSTED POPS/QPF DOWN ACROSS THE NORTH
WHILE MAINTAINING THEM SOUTH...AND HAVE EVEN BUMPED THINGS UP A
LITTLE RIGHT ALONG THE LOT/ILX BORDER AREA BASED ON MODEL CONSENSUS
THERE LATER THIS AFTERNOON/EVENING. HAVE ALSO TWEAKED SHORT TERM SKY
COVER A BIT TO ALLOW FOR THE COUPLE BREAKS OF SUN NOTED OUT THE
OFFICE WINDOW THIS MORNING.
RATZER
//PREV DISCUSSION...
329 AM CDT
SHORT TERM...TODAY THROUGH TUESDAY...
THE FORECAST CONCERNS REMAIN ON THE LATE SEASON WINTER STORM
BRINGING AT LEAST MINOR ACCUMULATING SNOW TO A FAIRLY LARGE PART OF
THE FORECAST AREA. WHILE THE MOST SIGNIFICANT ACCUMULATIONS AND
IMPACTS WILL BE DOWNSTATE IL AND IN...SNOWFALL AMOUNTS OF NEAR OR
IN EXCESS OF SIX INCHES ARE EXPECTED SOUTH OF U.S. HIGHWAY 24 IN
THE SOUTHERNMOST CWA COUNTIES. WAS ON THE FENCE WITH A WARNING OR
JUST A HIGHER END ADVISORY...BUT OPTED WARNING WITH CONFIDENCE
INCREASING IN WHERE THE SNOWFALL GRADIENT WILL BE...AS WELL AS FOR
COLLABORATION PURPOSES.
THE EARLY MORNING WATER VAPOR AND INFRARED SATELLITE LOOPS DEPICT
THE BROAD COLD CORE UPPER LOW OVER THE CENTRAL U.S. WITH THE
STRONG DEVELOPING EMBEDDED UPPER LOW QUICKLY ADVANCING ENE OVER
THE OZARKS. THIS IS ON THE LEADING EDGE OF A WELL-DEFINED UPPER
JET. IN ADVANCE OF THIS LOW IS A WEAK SHORTWAVE MOVING NORTHEAST
OVER THE FORECAST AREA EARLY THIS MORNING...HELPING TO BRING
SUBTLE ISENTROPIC ASCENT AND MOISTENING. OVERALL THE FORCING WITH
THIS IS NOT GREAT AND THE MOIST UPGLIDE BECOMES USED MORE SO BY
THE MAIN LOW TO THE SOUTHWEST...SO THE OVERALL PRECIP AREA WITH
THIS IS ANTICIPATED TO DECREASE IN COVERAGE AFTER DAYBREAK. THE
HRRR AND OTHER HIGH RESOLUTION MODELS AGREE WITH SUCH A TREND. ANY
SNOW THROUGH THE MORNING WITH THIS LOOKS TO MAINLY BE LIGHT...AND
THERE COULD BE A LITTLE HELP FROM SEEDER FEEDER PROCESSES AS THERE
ARE PATCHES OF STRATOCU ALREADY IN PLACE. THIS MAINLY ONLY LIGHT
SNOW THROUGH THE MORNING IS WHY THE HEADLINE START TIME REMAINS AT
1 PM.
THE UPPER LOW WILL CLEARLY SWING TO A NEGATIVE TILT THIS
AFTERNOON WITH A CLASSIC SYNOPTIC LOOK IN THE MODELS FOR HEAVY
SNOW ACROSS CENTRAL IL INTO PARTS OF IN...WITH INGREDIENTS OF DEEP
SATURATED ASCENT AND IMPRESSIVE STEEP ELEVATED LAPSE RATES. THE
TREND FROM 24 HOURS AGO HAS BEEN SOUTH WITH THE GUIDANCE IN ALL
THESE ELEMENTS...AND THAT HAS RESULTED IN A TIGHTENING OF THEIR
OUTPUT GRADIENT IN QPF AND SNOWFALL ACROSS THE SOUTHERN FORECAST
AREA...WHICH WAS FOR THE MOST PART ANTICIPATED. SNOWFALL AMOUNTS
FOR NORTH OF I-80 LOOK TO BE FAIRLY LIGHT AND MAYBE EVEN NOTHING
AT ALL...WHILE SOUTH OF I-80 THE SNOWFALL AMOUNTS ARE EXPECTED TO
INCREASE AND THEN RAPIDLY SOUTH OF HIGHWAY 24. EXPECT THAT
SNOWFALL WILL INCREASE IN INTENSITY ACROSS THE AREA BY EARLY
AFTERNOON IN THE SOUTH AND LATE AFTERNOON IN THE CENTRAL CWA AS
MORE SUBSTANTIAL HEIGHT FALLS AND ASSOCIATED ASCENT ENVELOP THE
AREA.
THE LATE AFTERNOON AND EVENING PERIOD IS WHERE MOST OF THE
ACCUMULATION IS ANTICIPATED...NOT ONLY FOR THE HEADLINE AREA BUT
ALSO IN THE MINOR ACCUMULATIONS NORTH OF THERE. ACROSS THE WARNING
AREA...THE ELEVATED THERMAL GRADIENT IS FORECAST TO TIGHTEN AT
THIS TIME IN THE GFS AND EC SOLUTIONS...WITH FRONTOGENETIC FORCING
INDICATED ON CROSS SECTIONS. MIXING RATIOS ON THE ISENTROPIC
LAYERS ARE AROUND 3 G/KG...AND REALIZING A PERIOD OF MORE MODEST
RATES LOOK LIKELY. SEVERAL OF THE CONVECTIVE ALLOWING GUIDANCE
MODELS DO BRING 35 PLUS DBZ EITHER NEAR OR INTO THIS AREA DURING
THIS PERIOD. WHILE IT DOES NOT LAST LONG...IT LOOKS LIKE THAT
SHOULD ENHANCE LOCAL TOTALS. THOUGH IT COULD BE JUST SOUTH OF THE
FORECAST AREA...ALWAYS A POTENTIAL PROBLEM IN THIS PORTION OF SUCH
A STRONGLY FORCED SYSTEM.
BY LATE TONIGHT...THE STRONGEST FORCING AND DEEPEST MOISTURE BEGIN
TO SLIDE EAST. EXPECT A GRADUAL TAPERING FROM SNOW TO SCATTERED
SNOW SHOWERS. NEAR LAKE MI...EVEN AS EARLY AS THIS
EVENING...THERE MAY BE SOME ENHANCEMENT...THOUGH IT IS
ANTICIPATED TO NOT BE ANYTHING OVERLY STRONG DUE TO LIMITED EL
HEIGHTS AND CONVERGENCE. LATER INTO THE NIGHT AND DURING MONDAY
MORNING THE FOCUS IS ANTICIPATED TO IMPROVE AS ARE THE 850MB TO
LAKE SURFACE TEMP DIFFERENCE /AROUND 12C/. SO HAVE BOOSTED POPS
FOR LAKE EFFECT SNOW SHOWERS OR FLURRIES IN CHICAGO DURING THE
MONDAY MORNING PERIOD AND THEN TRANSITIONING INTO NORTHWEST IN AS
THE SYNOPTIC FLOW BACKS SLIGHTLY WITH THE DEPARTING LOW. AMOUNTS
LOOK TO BE LIGHT AT THIS TIME...BUT THE OCCASIONAL LIGHT SNOW OR
FLURRIES MAY LAST OVER A LONG PERIOD EVEN INTO MONDAY NIGHT AND
TUE FOR NORTHWEST IN.
MTF
LONG TERM...WEDNESDAY THROUGH SUNDAY...
A LARGE RIDGE OF HIGH PRESSURE WILL BE OVER THE GREAT LAKES AND
OHIO VALLEY WEDNESDAY AND WILL SLOWLY MOVE EAST THURSDAY AND FRIDAY.
PROGRESSIVE NORTHWEST FLOW REMAINS ALOFT HOWEVER AND THERE ARE
VARIOUS WEAK WAVES PROGGED TO PASS ACROSS THE PLAINS AND INTO THE
OHIO VALLEY FROM MID WEEK INTO THE WEEKEND WITH SOME OF THESE LIKELY
REMAINING SOUTH OF THE AREA OR PERHAPS JUST CLIPPING THE SOUTHERN
CWA. FAIRLY LOW CONFIDENCE REGARDING ANY OF THESE WAVES AS WELL AS
THERE TIMING/LOCATION AND HAVE CONTINUED WITH A DRY FORECAST THROUGH
THE PERIOD.
TEMPERATURES BEGIN A SLOW WARMING TOWARD THE END OF THE WEEK ON THE
BACK SIDE OF THE HIGH. THOUGH THERE ARE SOME COMPLICATING FACTORS.
FIRST IS HOW MUCH SNOW FALLS AND HOW FAST IT MELTS. LATE MARCH
SUNSHINE HAS EASILY BOOSTED TEMPS INTO THE LOWER/MID 40S OVER BARE
GROUND AND THIS IS LIKELY THE STARTING RANGE...ASSUMING SUNSHINE.
BUT WITH THE WEAK GRADIENT AND LIGHT WINDS...EXPECT A LAKE BREEZE
WEDNESDAY...THURSDAY AND PROBABLY FRIDAY...ASSUMING A LACK OF
CLOUDS/PRECIP. AND THESE LAKE BREEZES WILL PROBABLY FORM FAIRLY
EARLY IN THE AFTERNOON...LIMITING HOW MUCH TIME LAKE SHORE AREAS
HAVE TO WARM UP BEFORE FLOW TURNS OF THE VERY CHILLY LAKE. HAVE
STARTED THE TREND FOR COOLER TEMPS NEAR THE LAKE BUT AS THESE TIME
PERIODS APPROACH...ADDITIONAL DETAILS CAN BE ADDED. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* SNOW OVERSPREADING NORTHEASTERN ILLINOIS THIS AFTERNOON...AND
POTENTIAL IMPACTS DUE TO VSBY/ACCUMULATIONS.
* GUSTY NORTHEAST WINDS AROUND 30 KT GRADUALLY BACKING TO NORTH.
* LAKE EFFECT SNOW SHOWERS DEVELOPING THIS EVENING AND OVERNIGHT.
BMD
//DISCUSSION...UPDATED 20Z...
EARLIER BAND OF SNOW MENTIONED OVER NORTH CENTRAL ILLINOIS FELL
APART QUICKER THAN ORIGINALLY ANTICIPATED RESULTING IN SNOW BEING
PUSHED BACK SEVERAL HOURS THIS AFTERNOON IN THE TAFS. ANOTHER
BAND OF SNOW LIFTING NORTH INTO THE I-80 CORRIDOR WILL LIKELY
SUFFER A SIMILAR FATE AS IT PUSHES INTO DRY AIR AND OVERALL
FORCING DIMINISHES. LATEST RAP/HRRR HOURLY GUIDANCE STILL TRY TO
BRING SOME PRECIP INTO THE CHICAGO TERMINALS EARLY THIS
EVENING...WITH HRRR STILL HINTING AT LAKE ENHANCEMENT.
PREVIOUS 18Z DISCUSSION...
TRICKY FORECAST THIS AFTERNOON DEALING WITH WHAT WILL LIKELY BE A
SHARP CUTOFF OF HEAVY SNOW ACCUMULATIONS WHICH ARE EXPECTED TO BE
SOUTH OF INTERSTATE 80 TO A DUSTING OR LESS ACROSS FAR NORTHERN
ILLINOIS. AFTERNOON RADAR IMAGERY SHOWS AN BATCH OF MODERATE SNOW
MOVING INTO NORTH CENTRAL ILLINOIS ON ITS WAY TOWARDS THE CHICAGO
TERMINALS 20-21Z. THIS AREA IS PRODUCING SNOW DROPPING VSBY TO
LESS THAN A MILE CURRENTLY...HOWEVER EXPECT THIS TO STRUGGLE TO
HOLD TOGETHER AS IT LIFTS INTO DRIER AIR AND AS OVERALL FORCING
DIMINISHES OVER NORTHERN ILLINOIS. LATEST SHORT TERM HOURLY
GUIDANCE AS WELL AS NAM AND SEVERAL HI-RES WRF RUNS ARE ALL IN
GOOD AGREEMENT KEEPING HEAVIEST QPF AXIS ALONG AND SOUTH OF
INTERSTATE 80. MANY OF THESE MODELS KEEP ORD/MDW DRY ALTOGETHER
WHILE OTHERS BRING UP A FEW HUNDREDTHS OF LIQUID EQUIVALENT
PRECIP. GIVEN RADAR TRENDS CANT RULE OUT A LIGHT DUSTING OF SNOW
AT THE TERMINALS THIS AFTERNOON...NOR A BRIEF DROP TO IFR
VSBY...HOWEVER THINK THIS TO BE UNLIKELY AS OF TAF ISSUANCE.
BREEZY NORTHWESTERLY WINDS WILL CONTINUE THROUGH THE REST OF THE
DAY INTO TONIGHT...LIKELY PICKING UP TO AROUND 30 KT THIS
AFTERNOON AND TAPERING SLIGHTLY LATE IN THE EVENING.
FOCUS WILL BE ON LAKE ENHANCED OR LAKE EFFECT SNOW THIS EVENING.
WIND TURNS TO NNE AROUND 00Z THIS EVENING WITH SHALLOW LAKE INDUCED
INSTABILITY POTENTIALLY ENHANCING OR DEVELOPING NEW SHOWERS.
EQUILIBRIUM LEVELS ARE MEAGER INITIALLY...BUT GRADUALLY DEEPEN TO
AROUND 070 BY 10Z AS THE WINDS VERY SLOWLY CONTINUE TO BACK TO THE
NORTH. CAN SEE THE LAKE EFFECT SIGNATURE IN SOME OF THE RAW GUIDANCE
OUTPUT INCLUDING THE GFS/ECMWF AND GEM...BUT PINNING DOWN THE
DETAILS IS HARD SINCE NONE OF THE HIGHER RES GUIDANCE SEEMS TO HINT
AT IT...EXCEPT FOR THE HRRR. THERE IS POTENTIAL FOR SOME LIGHT
ACCUMULATIONS AND IF A BAND DOES GET GOING COULDNT RULE OUT A QUICK
INCH IN SOME PLACES...BUT THINK THAT GIVEN THE MARGINAL THERMAL
CONDITIONS THIS MAY AMOUNT TO LITTLE MORE THAN VERY LIGHT SNOW OR
FLURRIES.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* DECREASING CONFIDENCE THAT SNOW WILL IMPACT THE TERMINALS
RESULTING IN REDUCED VSBY OR ANY ACCUMULATION.
* LOW CONFIDENCE IN TIMING/IMPACTS OF LAKE EFFECT SNOW THIS EVENING.
* HIGH CONFIDENCE IN CIG TRENDS.
* HIGH CONFIDENCE IN WIND TRENDS.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY...MVFR CIGS LIKELY. CHANCE OF LAKE EFFECT SNOW SHOWERS.
TUESDAY...MVFR CIGS.
WEDNESDAY...VFR.
THURSDAY AND FRIDAY...VFR.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...MVFR CIGS LIKELY. CHANCE OF LAKE EFFECT SNOW
SHOWERS.
TUESDAY...MVFR CIGS.
WEDNESDAY THROUGH SATURDAY...VFR.
TRS
&&
.MARINE...
153 PM CDT
THE MAIN WEATHER CONCERNS THROUGH THE PERIOD CONTINUE TO FOCUS ON
THE SIGNIFICANT STORM SYSTEM AFFECTING THE LAKE TONIGHT THROUGH
MONDAY. WINDS HAVE BEGAN INCREASING UP TO 25 TO 30 KT OUT OF THE
EAST-NORTHEAST ALREADY IN RESPONSE TO AN AREA OF DEEPENING LOW
PRESSURE MOVING EAST-NORTHEASTWARD ACROSS WESTERN KENTUCKY EARLY
THIS AFTERNOON. THIS LOW WILL CONTINUE ACROSS THE OHIO VALLEY
TONIGHT...THEN MERGE WITH A NEW LOW MOVING UP THE CENTRAL ATLANTIC
COAST LATER MONDAY. IT APPEARS THE WINDS WILL CONTINUE TO INCREASE
OVER THE NEXT SEVERAL HOURS...WITH GALES OF 35 TO 40 KT BECOMING
LIKELY BY LATE AFTERNOON ACROSS THE FAR SOUTHERN END OF LAKE
MICHIGAN. LATE TONIGHT AND INTO MONDAY THE FLOW WILL TURN MORE
NORTHERLY AS THE LOW MOVES ACROSS THE OHIO VALLEY. IT APPEARS SOME
GALES COULD PERSIST INTO THE EARLY MORNING HOURS...BEFORE EASING
SLIGHTLY TO 30 KT. I UPGRADED THE SMALL CRAFT ADVISORY TO A GALE
WARNING FOR THE ILLINOIS AND INDIANA SHORES...AND I INCLUDED THE
OPEN WATERS OF FAR SOUTHERN LAKE MICHIGAN FOR LATE THIS AFTERNOON
THROUGH MONDAY MORNING.
THE LONG NORTHERLY FETCH WILL RESULT IN SOME VERY HIGH WAVES ACROSS
THE SOUTHERN END OF THE LAKE...INCLUDING THE NEAR SHORE WATERS.
THESE LARGE WAVES WILL LIKELY PROLONG HAZARDOUS CONDITIONS FOR SMALL
CRAFT FOR BOTH THE ILLINOIS AND THE INDIANA NEAR SHORE WATERS BEYOND
THE GALE PERIOD. HOWEVER...CONDITIONS WILL BEGIN TO IMPROVE BY MID
WEEK AS A SURFACE RIDGE OF HIGH PRESSURE APPROACHES THE WESTERN
LAKES. THIS WILL LIKELY RESULT IN A PERIOD OF LIGHT AND VARIABLE
WINDS INTO THE END OF THE WEEK.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ033-ILZ039 UNTIL 7 AM MONDAY.
WINTER WEATHER ADVISORY...ILZ023-ILZ032 UNTIL 7 AM MONDAY.
IN...WINTER WEATHER ADVISORY...INZ010-INZ011 UNTIL 7 AM MONDAY.
WINTER STORM WARNING...INZ019 UNTIL 7 AM MONDAY.
LM...GALE WARNING...LMZ080-LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ876-LMZ878 UNTIL 4 AM MONDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 5 PM SUNDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...4 AM MONDAY TO 7 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1148 PM CDT SAT MAR 23 2013
.DISCUSSION...
ISSUED 907 PM CDT SAT MAR 23 2013
WHILE THINGS WILL BE MOSTLY QUIET FOR THE NEXT SEVERAL HOURS
ACROSS CENTRAL AND SOUTHEAST ILLINOIS...A SIGNIFICANT EARLY SPRING
STORM IS STILL ON TRACK TO IMPACT THE AREA STARTING LATE TONIGHT
AND THROUGHOUT SUNDAY.
IT IS APPARENT THROUGH SURFACE OBS/SATELLITE LOOPS/00Z KILX
SOUNDING THAT THE LOCAL AIRMASS IS STILL PRETTY DRY AND WILL NEED
TO UNDERGO QUITE A BIT OF MOISTENING FOR SIGNIFICANT PRECIPITATION
TO OCCUR. A DRY NORTHEASTERLY FLOW FROM 800 MB TO THE SURFACE
SHOULD ALSO HELP TO LIMIT THE PRECIPITATION THREAT FOR A TIME. IN
ADDITION...THE UPPER LOW DRIVING THE STORM HAS ONLY RECENTLY
STOPPED DIGGING ACROSS THE SOUTHERN PLAINS...PER WATER VAPOR
LOOPS...AND IT WILL STILL TAKE SOME TIME TO GET HERE.
THE BULK OF THE FORECAST MODELS SUGGEST INCREASING WAA/ISENTROPIC
LIFT THROUGH THE NIGHT WILL HELP TO PROVIDE TOP DOWN MOISTENING...
ALLOWING MOST AREAS TO SEE LIGHT PRECIPITATION BY DAYBREAK SUNDAY.
HOWEVER...THE LATEST RUNS OF THE SHORT RANGE/HIGH RESOLUTION HRRR
AND RAP MODELS SUGGEST MUCH OF THE PRECIPITATION FALLING THROUGH
THE NIGHT WILL SIMPLY MOISTEN THE DRY AIR AND PRODUCE FAIRLY
MINIMAL PRECIPITATION AT THE SURFACE. THE HEAVIER SNOWFALL IS
STILL NOT EXPECTED TO ARRIVE UNTIL VERY LATE SUNDAY MORNING AND
THROUGH THE AFTERNOON.
THE LOW LEVEL THERMAL PROFILE IN THE 00Z KILX AND FORECAST
SOUNDINGS SUGGEST ENOUGH LOW LEVEL WARM AIR IN PLACE FOR THE
PRECIP TO START AS RAIN IN MANY AREAS. THE EVAPORATIVE COOLING DUE
TO THE DRY AIR/CONTINUED DRY LOW LEVEL FLOW SHOULD QUICKLY CHANGE
THE PRECIP OVER TO SNOW.
MOST OF FORECAST IS IN PRETTY GOOD SHAPE. HOWEVER...PLAN TO BACK
OFF ON POPS/PCPN AMOUNT A BIT TONIGHT BASED ON THE FACTORS
MENTIONED ABOVE. WILL NOT MAKE ANY HEADLINE ADJUSTMENTS AT THIS
TIME.
BAK
&&
.AVIATION...
ISSUED 1148 PM CDT SAT MAR 23 2013
PRECIPITATION BEGINNING TO BREAK OUT ACROSS CENTRAL ILLINOIS...
AND THIS TREND SHOULD SEE CONDITIONS DEGRADING TO IFR
OVERNIGHT/EARLY SUNDAY AS A STRONG STORM SYSTEM SPREADS SNOW INTO
THE REGION FROM THE SOUTHWEST. THERE WILL BE TWO HEAVIER WAVES OF
SNOWFALL...THE FIRST SHOULD OCCUR A FEW HOURS EITHER SIDE OF
SUNRISE SUNDAY...WITH THE SECOND OCCURRING SUNDAY AFTERNOON. WHILE
THERE MAY BE A BREAK LATER SUNDAY MORNING WHERE CONDITIONS BRIEFLY
IMPROVE ABOVE IFR...BUT CONFIDENCE IN THE DETAILS IS NOT HIGH.
NORTHEAST WINDS WILL PREVAIL THROUGH THE PERIOD AS THE TERMINALS
LIE TO THE NORTH/WEST OF THE MAIN STORM TRACK. EXPECT WINDS TO
BECOME QUITE GUSTY AT TIMES DURING THE DAY SUNDAY WHICH IS LIKELY
TO COINCIDE WITH THE HEAVIEST SNOWFALL AND RESULT IN THE LOWEST
VISIBILITIES.
BAK
&&
.PREV DISCUSSION...
ISSUED 255 PM CDT SAT MAR 23 2013
SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
THREAT FOR HEAVY WET SNOW OVER PORTIONS OF CENTRAL...EAST CENTRAL
AND SOUTHEAST ILLINOIS CONTINUES FOR SUNDAY THROUGH SUNDAY NIGHT.
MAJOR SPRING SNOW EVENT STARTING TO TAKE SHAPE OVER THE SOUTHERN
ROCKIES THIS AFTERNOON WITH PRECIP ALREADY BLOSSOMING WEST OF THE
MISSOURI RIVER IN THE MID LEVEL WARM ADVECTION/ISENTROPIC LIFT
REGION. AS THE AREA OF ENHANCED LIFT SHIFTS ENE INTO THE MIDWEST
LATER THIS EVENING...WE SHOULD SEE SOME RAIN AND SNOW DEVELOP TO
THE WEST OF THE MISSISSIPPI RIVER AND SPREAD EAST INTO WEST CENTRAL
ILLINOIS LATER THIS EVENING AND THEN SLOWLY TO THE EAST BY SUNDAY
MORNING. NAM-WRF CONTINUING TO DEPICT TWO SIGNIFICANT AREAS OF
LIFT WITH THIS STORM. THE INITIAL BAND OF LIFT/ISENT ASCENT PUSHES
ACRS THE AREA IN THE 06Z-15Z TIME FRAME...WITH A LULL IN THE MORE
INTENSE SNOWFALL AND THEN PICK UP AGAIN WITH THE SECOND AND MORE
CONCENTRATED AREA OF FORCING ASSOCIATED WITH THE CLOSED 500 MB LOW.
CROSS SECTIONS THROUGH THE HEART OF OUR CWA SHOWING THESE TWO DISTINCT
AREAS OF LIFT WELL WITH BOTH ASSOCIATED WITH DEEP MOISTURE AND
CONCENTRATED OMEGA IN THE FAVORED DENDRITIC ZONE. AS THE DEFORMATION
ZONE TRACKS ACRS THE REGION TOMORROW AFTERNOON AND EVENING ASSOCIATED
WITH THE MORE POTENT FORCING...THERE ARE A FEW AREAS OF NEGATIVE
EPV SHOWING UP ON THE CROSS SECTIONS JUST NORTH OF STL ENE TO JUST
SOUTH OF ROUTE 36 OVER CENTRAL IL. FORECAST SOUNDINGS ALSO SHOWING
A SMALL AREA OF MOST UNSTABLE CAPES IN THAT CORRIDOR AS WELL SUGGESTING
A CONTINUING THREAT FOR ISOLATED CONVECTION ASSOCIATED WITH THE HEAVIER
BURSTS OF SNOW. TROWAL SIGNATURE SHOWING UP ON THE 305K PRESSURE SURFACE
AS WELL SUNDAY EVENING WHICH WILL PROLONG THE SNOW EVENT ACROSS THE
EAST WITH ADDITIONAL ACCUMULATIONS POSSIBLE. NOT MUCH OF A THREAT FOR
BLOWING SNOW SUNDAY WITH SFC TEMPS AT OR ABOVE FREEZING...BUT THAT MAY
BE A DIFFERENT STORY SUNDAY NIGHT AS GUSTY NORTH TO NORTHWEST WINDS
AND COLDER TEMPERATURES BRING ABOUT AT LEAST A THREAT FOR SOME BLOWING
SNOW...ESP ACROSS THE NORTH AND EASTERN COUNTIES.
AS A RESULT...HAVE UPGRADED THE WATCH TO A WARNING FOR ALL AREAS EXCPT
ALONG AND NW OF THE ILLINOIS RIVER. HAD INITIALLY THOUGHT OF GOING
WITH AN ADVISORY FOR OUR SOUTHEAST COUNTIES...BUT BASED ON THE TRACK
OF THE CLOSED 850 AND 500 MB LOWS ON THE NAM-WRF AND SREF...THOUGHT
THE THREAT FOR ISOLD THUNDER SNOW...JUST NORTH OF THE RAIN-SNOW LINE...
WOULD BE ENHANCED. SO BUMPED UP THE SNOW NUMBERS IN SE IL WITH AMOUNTS
IN THE 5 TO 7 INCH RANGE. CARRIED THE WARNING INTO MONDAY MORNING ACRS
EAST CENTRAL IL BASED ON THE SLOWER TREND SHOWING UP ON MODELS THE PAST
FEW RUNS.
CYCLONIC FLOW IN THE WAKE OF THE DEPARTING STORM ON MONDAY AND MONDAY
NIGHT WILL YIELD SCATTERED SNOW SHOWERS OR FLURRIES ALONG WITH A
CONTINUATION OF THE UNSEASONABLY COLD TEMPERATURES FOR THE THIRD WEEK
OF MARCH.
LONG TERM...TUESDAY THROUGH SATURDAY...
THE CHILLY WEATHER WILL CONTINUE INTO TUESDAY AS THE UPPER LOW
SHIFTS TO THE EAST COAST...WITH 850 MB TEMPS LINGERING AROUND -10C.
HOWEVER...THE SECOND HALF OF THE WEEK WILL FEATURE SOME GRADUALLY
MODERATING AIR AS RIDGING SLOWLY BUILDS OVER THE WESTERN HALF OF THE
NATION. HIGHS CLOSER TO NORMAL FOR THIS TIME OF YEAR... I.E. 50S...
EXPECTED BY FRIDAY AND SATURDAY.
AFTER A SURFACE HIGH PRESSURE RIDGE SLOWLY MOVES THROUGH THE MIDWEST
WEDNESDAY AND WEDNESDAY NIGHT...NEXT FOCUS REMAINS WITH A SHORTWAVE
PASSING THROUGH LATE WEEK. LATEST ECMWF IS QUITE BULLISH WITH THE
PRECIP FRIDAY AND FRIDAY NIGHT...WHEREAS THE GFS IS ABOUT 12-18
HOURS FASTER WITH THIS. HAVE CONCENTRATED THE PRECIP CHANCES IN THE
GRIDS IN THE FRIDAY NIGHT TIME FRAME...ALTHOUGH CONFIDENCE IS NOT
ESPECIALLY HIGH AT THE MOMENT.
SHORT TERM...SMITH
LONG TERM....GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 1 AM CDT MONDAY FOR ILZ037-040>042-
047>054-061-066-071.
WINTER STORM WARNING FROM 4 AM SUNDAY TO 7 AM CDT MONDAY FOR
ILZ038-043>046-055>057-062-063-067-068-072-073.
WINTER WEATHER ADVISORY UNTIL 1 AM CDT MONDAY FOR ILZ027>029-036.
WINTER WEATHER ADVISORY FROM 4 AM SUNDAY TO 7 AM CDT MONDAY FOR
ILZ030-031.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
337 PM EDT SUN MAR 24 2013
.SHORT TERM...
TONIGHT...MONDAY...MONDAY NIGHT...
LATEST WATER VAPOR IMAGERY SHOWING POTENT UPPER TROUGH AND
ASSOCIATED VORT MAX PUSHING ACROSS MISSOURI THIS AFTERNOON. LOW-MID
LEVEL ASCENT AHEAD OF THIS FEATURE IS RESULTING IN A LARGE SWATH OF
HEAVY SNOW OVER EASTERN MO AND WEST CENTRAL IL. RADAR IMAGERY
DEPICTING CONVECTIVE ELEMENTS EMBEDDED WITHIN THIS SNOW BAND WHICH
MAY ACT TO HINDER MOISTURE TRANSPORT NORTHWARD INTO OUR AREA AS THIS
SYSTEM CONTINUES TO MOVE E/NE THIS EVENING. 12Z RAOBS CONFIRMING
LATEST RAP ANALYSIS SHOWING STRONG UPPER JET TRAVERSING THROUGH THE
BASE OF THIS TROUGH...ASSOCIATED UPPER LEVEL DIVERGENCE EXPECTED TO
AID IN THE CONTINUATION OF HEAVY SNOW BAND AS IT MOVES INTO
CENTRAL/NORTHERN INDIANA TONIGHT. MODELS IN DECENT AGREEMENT IN NE
TRACK OF SFC LOW...BRINGING IT INTO NORTHERN KY BY 00Z MON AND UP
INTO SW OH BY 12Z MON...PLACING OUR SOUTHERN CWA IN FAVORABLE AREA
FOR FOR HEAVY SNOW. KEY COMPONENT IN THE EVOLUTION OF THIS SYSTEM
THAT WILL ACT TO LIMIT SNOW ACCUMULATIONS IS THE EASTWARD
PROGRESSION OF UPPER JET DYNAMICS AND THE RESULTING COASTAL TRANSFER
OF ENERGY. THIS WILL RAPIDLY DISSIPATE OH VALLEY SFC LOW MONDAY IN
FAVOR OF INTENSIFICATION OF COASTAL LOW AS CLOSED UPPER LOW
CONTINUES ON EASTWARD TRACK AND BECOMES NEARLY VERTICALLY STACKED
WITH SFC LOW OVER OH VALLEY 09-12Z MON. THAT SAID...THERE STILL
EXISTS A 12 HOUR WINDOW...00Z-12Z MON...OF FAVORABLE CONDITIONS FOR
ACCUMULATING SNOW AS ALL MODELS IN GOOD AGREEMENT WITH PRODUCING 6-8
INCHES OVER THE FAR SOUTHERN PORTION OF THE CWA AS 80-100M 500MB HT
FALLS WILL REACH UP INTO THE SOUTHERN CWA AS UPPER LOW TRACKS
THROUGH KY OVERNIGHT. AND WHILE MODELS VARY ON DEGREE OF DEEP
MOISTURE AVAILABLE...AMPLE LOW LEVEL MOISTURE ALONG WITH BETTER
ALIGNMENT OF OMEGA AND DGZ THAN PREVIOUS RUNS WILL ALSO FAVOR A GOOD
SHOT AT HVY SNOW FOR AT LEAST A BRIEF PERIOD OF TIME OVERNIGHT
ACROSS THE SOUTHERN TIER OF THE FCST AREA. WILL THEREFORE CONTINUE
WITH WARNING/ADV AREAS AND KEEP NORTHERN TIER WITHOUT HEADLINES AS
DISTINCT CUTOFF IN SNOW EXPECTED NORTH OF US6. IN THE WAKE OF THIS
SYSTEM FLOW WILL GRADUALLY BACK FROM NE TO N/NW LATE IN THE DAY
MONDAY AND BRING CHANCE FOR LES INTO OUR EXTREME NW CWA. DESPITE
UNIFORM NORTHERLY FLOW DOWN THE LONG AXIS OF LAKE MICHIGAN...LACK OF
COLD AIR WILL YIELD MARGINAL/SUB MARGINAL DELTA T AND THEREFORE
HINDER ACCUMULATIONS.
&&
.LONG TERM...
TUESDAY THROUGH SUNDAY...INCREASED SNOW CHANCES TUESDAY AND TUESDAY
NIGHT OVER AREAS DOWNSTREAM OF LAKE MICHIGAN AS VERY COLD AIR
CONTINUES TO SPREAD SOUTH OVER THE WESTERN GREAT LAKES REGION. DELTA
T VALUES RATHER MODEST AT 12C TO 14C...BUT A LONG LAKE AXIS FETCH
WITH LIKELY PRECONDITIONING FROM LAKE SUPERIOR SHOULD ALLOW FOR SOME
ORGANIZATION OF SNOW SHOWERS OVER THE LAKE. RAISED SNOWFALL AMOUNTS
TUESDAY...HOWEVER...DAYTIME HEATING SHOULD LIMIT SNOW ACCUMULATIONS.
INVERSIONS HEIGHTS SHOULD FALL LATE TUESDAY NIGHT...BRINGING AN END
TO THE SNOW SHOWERS. HIGH AND LOW FCST TEMPERATURES ARE CHALLENGING
EARLY IN THE PERIOD GIVEN LOCATIONS AND AMOUNTS OF LINGERING SNOW
COVER AND A GRADUALLY MODIFYING AIRMASS. ANTICIPATED SOME SNOW COVER
SHOULD BE REMAINING OVER THE SOUTHERN THIRD OF THE AREA...SO HAVE
MADE SOME TEMPERATURE MODIFICATIONS TO THESE AREAS. OTHERWISE...
TEMPERATURES SHOULD STILL STRUGGLE TO GET BACK TO NORMAL. PREFERRED
THE COLDER GFS MEAN MOS TEMPERATURES THAT SEEM TO TAKE INTO ACCOUNT
A CHILLY MODIFYING AIRMASS. THE ECMWF IS EVEN COLDER THAN THE
GFS...WITH 850 MB TEMPS STAYING BELOW 0C EXCEPT FOR LATE SUNDAY.
&&
.AVIATION... / 18Z TAFS/
INITIAL WAVE HAS DEPARTED EAST OF OUR AREA WHICH WILL KEEP
CONDITIONS DRY THROUGH THE REMAINDER OF THE AFTERNOON. THE ONLY
EXCEPTION IS AT KFWA WHERE A FEW HEAVIER SNOW SHOWERS MAY MOVE
THROUGH OVER THE NEXT FEW HOURS. AFTER THAT...THE MAIN WAVE WILL
REACH THE AREA DURING THE EVENING HOURS WITH THE HEAVIEST SNOWFALL
ARRIVING BETWEEN 10PM AND MIDNIGHT. HEAVIEST SNOWFALL ANTICIPATED
AT KFWA...CLOSER TO THE SURFACE LOW...WHILE KSBN WILL BE ON THE
NORTHERN FRINGE OF THE PRECIPITATION SHIELD. ANTICIPATE SNOWFALL
TO TAPER OFF FROM NORTHWEST TO SOUTHEAST DURING THE MORNING HOURS
AS THE LOW PRESSURE SYSTEM DEPARTS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 10 AM EDT /9 AM CDT/ MONDAY FOR
INZ008-009-012>018.
WINTER STORM WARNING UNTIL 10 AM EDT MONDAY FOR INZ020-022>027-
032>034.
MI...NONE.
OH...WINTER WEATHER ADVISORY UNTIL 2 PM EDT MONDAY FOR OHZ004-005-015-
016.
WINTER STORM WARNING UNTIL 2 PM EDT MONDAY FOR OHZ024-025.
LM...SMALL CRAFT ADVISORY UNTIL 5 AM EDT TUESDAY FOR LMZ043-046.
&&
$$
SHORT TERM...JAL
LONG TERM...SKIPPER
AVIATION...JAL
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
251 PM EDT SUN MAR 24 2013
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 322 AM EDT SUN MAR 24 2013
A STRENGTHENING LOW PRESSURE SYSTEM WILL LIFT NORTHEAST ACROSS
EASTERN KENTUCKY TODAY AND THIS EVENING BEFORE MOVING INTO SOUTHERN
OHIO OVERNIGHT. THIS SYSTEM IS EXPECTED TO BRING SIGNIFICANT WET
SNOW ACCUMULATION TO CENTRAL INDIANA ESPECIALLY CONSIDERING IT IS
LATE MARCH. SNOW ACCUMULATION WILL BE HEAVIEST LATE THIS AFTERNOON
AND TONIGHT. SCATTERED SNOW SHOWERS WILL LINGER BEFORE HIGH PRESSURE
GRADUALLY BUILDS IN FROM THE PLAINS BRINGING DRY WEATHER AND
GRADUALLY WARMING TEMPERATURES THROUGH LATE WEEK. BY
SATURDAY...HIGHS COULD BE NEAR NORMAL MOSTLY IN THE 50S WITH RAIN
SHOWER CHANCES IN SOUTHERLY FLOW ON THE BACK SIDE OF HIGH PRESSURE.
&&
.NEAR TERM /REST OF TODAY AND TONIGHT/...
ISSUED AT 1026 AM EDT SUN MAR 24 2013
AT 10 AM LOW PRESSURE OF JUST UNDER 1000 MB WAS CENTERED NEAR THE
MISSOURI BOOT HEEL. RADAR SHOWS MOST SNOWFALL HAS ENDED MOMENTARILY
ACROSS CENTRAL INDIANA WITH MODERATE TO HEAVY SNOW ACROSS WESTERN
AND SOUTHERN ILLINOIS AND RAIN SOUTH OF THERE. SLEET HAS ALSO BEEN
REPORTED WITHIN THE PAST COUPLE HOURS. TEMPERATURES IN THE AREA
RANGE FROM THE UPPER 20S IN THE NORTHEAST TO THE MIDDLE 30S ACROSS
THE SOUTH.
FOR THE UPDATE LEANED HEAVILY ON HRRR FOR TIMING OF RETURN OF
PRECIP BUT SPED UP BY A COUPLE HOURS BASED ON COMPARISON WITH
CURRENT RADAR ECHOES. WITH TRACK OF 6Z NAM JUMPING NORTH AND RAP
OVERDOING WARM INTRUSION COMPARED TO OBSERVATIONS USED SREFS AND
GFS FORECAST SOUNDINGS FOR PRECIP TYPE. ADDED SOME TIMING TO THE
POPS FOR THE REST OF THE DAY TO INDICATE A LULL IN ACTIVITY DURING
THE MORNING WITH POPS RAPIDLY INCREASING FROM THE WEST IN THE 11
AM TO NOON TIME FRAME AND OVERSPREADING THE AREA FROM THERE.
FORECAST SOUNDINGS INDICATE SOME POTENTIAL FOR SLEET TO MIX IN AS
FAR NORTH AS THE I-70 CORRIDOR SO ADDED A CHANCE FOR SLEET THERE
THROUGH MUCH OF THE AFTERNOON. MAINTAINED A MIX OF RAIN AND SNOW
IN THE SOUTH WITH THE AFOREMENTIONED SLEET POTENTIAL. SOUNDINGS
INDICATE A CHANGEOVER TO ALL SNOW BY AROUND 22-23Z. SOME CONCERN
THAT MIX OF RAIN AND SLEET WITH THE SNOW COULD DROP SNOWFALL
ACCUMULATION IN THE SOUTH DURING THE TODAY PERIOD BY A DECENT
AMOUNT...BUT THIS IS COUNTERACTED BY SIGNIFICANT SNOWFALL RATES
UPSTREAM IN SOUTHWESTERN AND CENTRAL ILLINOIS OF 1-3 INCHES PER
HOUR AND THUS MAKING NO APPRECIABLE CHANGES TO SNOWFALL AMOUNTS AT
THIS TIME. WITH OBSERVATIONS OF A FEW LIGHTNING STRIKES UPSTREAM
AND SYSTEM ONLY PROGGED TO STRENGTHEN AS IT ARRIVES ADDED A
SLIGHT CHANCE FOR THUNDER SOUTH OF INTERSTATE 70 AS WELL.
PREVIOUS DISCUSSION FOLLOWS...
MAIN CHALLENGE TODAY WILL BE PRECIPITATION TIMING AND TYPE
ALONG WITH SNOW AMOUNTS AS MODELS ARE NOW COMING TOGETHER NICELY
IN HANDLING THE STRENGTH AND LOCATION OF LOW PRESSURE SYSTEM THAT
IS PROGGED TO LIFT NORTHEAST FROM THE SOUTHERN STATES TO EAST
CENTRAL KENTUCKY BY 00Z MONDAY. STRONG UPPER LOW MOVING TO NEAR THE
CONFLUENCE OF THE OHIO AND MISSISSIPPI RIVERS ALONG WITH A VIGOROUS
140 PLUS KNOT JET ACROSS THE TENNESSEE VALLEY WILL RESULT IN THE
AFOREMENTIONED SURFACE LOW DEEPENING TO LESS THAN 995 MILLIBARS BY
EVENING AND RESULT IN MODERATE TO HEAVY SNOW BY LATE AFTERNOON.
WITH MODELS TRENDING A LITTLE BIT FURTHER SOUTH THAN PREVIOUS
RUNS...HEAVIEST SNOW TODAY SHOULD BE ALONG AND SOUTH OF INTERSTATE
70 AND TO THE NORTH OF THE MIXED AREA. THIS AREA WILL ALSO BE NEAR
ELONGATED 850 MILLIBAR FRONTOGENESIS AND INSTABILITY ALOFT THAT
COULD AID IN SNOW AMOUNTS...ALTHOUGH SNOW RATIOS WILL BE ON THE LOW
SIDE UNTIL LATE IN THE DAY WHEN THE COLUMN COOLS FURTHER AS THE LOW
MOVES INTO SOUTHERN OHIO. AT THIS POINT...STRONG DYNAMICS INCLUDING
QVECTOR CONVERGENCE FROM 850-500 MILLIBARS ALONG WITH
FRONTOGENETICAL FORCING...DIFFLUENT FLOW ALOFT AND INSTABILITY
ALOFT SHOULD RESULT IN MODERATE TO HEAVY SNOW WITH BANDING PRODUCING
THE HIGHEST AMOUNTS.
SNOWFALL AMOUNTS WILL CONTINUE TO BE TRICKY...WITH THE GROUND AND
SURFACE TEMPERATURES STARTING OFF ABOVE FREEZING WHICH SHOULD LOWER
SNOW AMOUNTS FROM WHAT EARLIER MODEL RUNS HAD...UPWARDS OF 12 INCHES
IN THE HEAVIEST SNOW BAND. BUFKIT SUGGESTS THIS SCENARIO ALONG WITH
DECENT COMPACTION OF THE SNOW. ALSO...EXACT AREA OF PROLONGED
BANDING STILL UP IN THE AIR...HOWEVER A WIDESPREAD 6 INCH STORM
TOTAL SNOW AMOUNT LOOKS GOOD THROUGH MONDAY MORNING WITH 10 INCH
AMOUNTS AND LOCALLY HIGHER NEAR THE DEFORMATION ZONE WHICH SHOULD BE
FAIRLY CLOSE TO EITHER SIDE OF THE INTERSTATE 70 CORRIDOR AND A BIT
FURTHER NORTH OF THE LATE AFTERNOON HEAVY SNOW. WITH MODEL LOW
TRACKS AND RESULTANT SNOWFALL ACCUMULATION A LITTLE FURTHER
SOUTH...WILL UPGRADE THE SOUTHERNMOST TIER TO A WINTER STORM WARNING
AND KEEP THE WARNING GOING ELSEWHERE THROUGH NOON EDT MONDAY.
POPS WILL INCREASE TO OCCASIONAL FROM SOUTHWEST TO NORTHEAST TODAY
WITH MOST OR ALL OF CENTRAL INDIANA SEEING PRECIPITATION BY 18Z.
POPS WILL ONLY DROP SLIGHTLY TO LIKELY TOWARD MORNING.
COULD ALSO SEE SOME BLOWING SNOW TODAY AS BUFKIT SUGGESTS GUSTS TO
30 MPH OR MORE.
WITH THICK CLOUDS AROUND TODAY ALONG WITH EVAPORATIVE
COOLING...COLDER NAM MOS AND ALLBLEND TEMPERATURES IN THE
LOWER 30S NORTH TO THE MID 30S SOUTH LOOK GOOD.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 322 AM EDT SUN MAR 24 2013
MODELS AGREE THAT THROUGH THEIR QPF FIELDS THAT THE SNOW WILL BE
WINDING DOWN ON MONDAY WITH ONLY LINGERING SMALL SNOW SHOWER CHANCES
THROUGH TUESDAY. FINALLY...COULD SEE SOME CLEARING AND THE COLDEST
TEMPERATURES OF THE WEEK TUESDAY NIGHT WITH THE SNOW PACK SERVING TO
MAXIMIZE RADIATIONAL HEAT LOSS TO SPACE.
AFTERNOON TEMPERATURES WILL BE WELL BELOW NORMAL WITH THE
SNOW...NORTHWEST WINDS AND CLOUD COVER.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 251 PM EDT SUN MAR 24 2013
AFTER THE BUSY WEATHER EXPECTED OVER THE NEXT 24 HOURS...THE
EXTENDED PERIOD LOOKS MUCH QUIETER. OHIO VALLEY WILL STILL BE IN
COLD CYCLONIC FLOW IN THE WAKE OF THE STRONG STORM...BUT HIGH
PRESSURE WILL BE BUILDING IN WITH DRY WEATHER FOR MUCH OF THE
SECOND HALF OF THE WEEK. UPPER FLOW PATTERN WILL GRADUALLY
TRANSITION TO NORTHWEST FLOW ALOFT WITH TEMPS GRADUALLY WARMING
THROUGH THE END OF THE WEEK. A WEAK DISTURBANCE ALOFT WILL PASS
THROUGH THE LOWER OHIO VALLEY FRIDAY AND FRIDAY NIGHT WITH A SMALL
CHANCE FOR RAIN SHOWERS. A MUCH BETTER CHANCE FOR RAIN TO COME
SUNDAY AS A COLD FRONT MOVES ACROSS THE REGION.
UNDERCUT LOW TEMPS FROM MOS GUIDANCE BOTH TUESDAY/WEDNESDAY NIGHTS
WITH LIKELIHOOD OF RESIDUAL SNOW COVER. HIGHS WILL GRADUALLY WARM
BACK INTO THE 50S BY THE WEEKEND AND ALLBLEND CAPTURED THIS IDEA
WELL.
&&
.AVIATION /DISCUSSION FOR 241800Z TAF ISSUANCE/...
ISSUED AT 126 PM EDT SUN MAR 24 2013
CONDITIONS WILL RAPIDLY DETERIORATE LATE THIS AFTERNOON TO VLIFR
WITHIN HEAVY SNOW. IFR AND LOWER CONDITIONS WILL PERSIST INTO
MONDAY AFTERNOON.
CENTRAL INDIANA REMAINS WITHIN A DRY SLOT IN THE WAKE OF THE
MORNING SNOW. THE CALM BEFORE THE STORM IF YOU WILL AS HEAVY
PRECIP MOVING EAST ACROSS ILLINOIS AHEAD OF A DEEPENING LOW
PRESSURE. LOW LEVEL THERMAL ANALYSIS STILL SHOWING A WARM PUNCH
ALOFT MOVING ACROSS THE SOUTHERN HALF OF THE FORECAST AREA OVER
THE NEXT 3-4 HOURS BEFORE 850MB TEMPS CRASH. THIS IS LIKELY TO
ENABLE A PERIOD OF MIXING WITH RAIN...SLEET AND SNOW AT KBMG
BEGINNING AROUND OR SHORTLY AFTER 20Z. MAY EVEN SEE A BIT OF SLEET
MIX AT KIND IN THE 20-21Z TIME PERIOD. ANY MIXING WILL BE SHORT-
LIVED HOWEVER AS EVAPORATIVE COOLING TAKES PLACE THROUGH THE
BOUNDARY LAYER...WITH PRECIP CHANGING TO ALL SNOW AT BOTH KIND AND
KBMG AFTER 21Z.
SNOW WILL BECOME HEAVY BY EARLY EVENING AT ALL TERMINALS AS AXIS
OF DEEPEST FORCING WITH A STRONG WELL DEVELOPED TROWAL SETS UP IN
THE VICINITY OF THE I-70 CORRIDOR. CONSIDERING REPORTS TO THE WEST
OVER MISSOURI AND ILLINOIS AND THE ANTICIPATION THAT THE LOW
STRENGTHENS FURTHER AS IT MOVES INTO THE REGION THIS EVENING...
EXPECT A 3-6 HOUR PERIOD OF VERY HEAVY SNOWFALL WITH VISIBILITIES
AT OR UNDER 1/4SM. CONVECTIVE POTENTIAL AS WELL THROUGH THE
EVENING...ENHANCING SNOWFALL RATES WITHIN ANY THUNDERSNOW. HAVE
LEFT OUT ANY CB MENTION AT THIS TIME...BUT GREATEST POTENTIAL FOR
THUNDERSNOW WILL BE WITHIN THE HEAVIEST SNOWFALL DURING THE
EVENING.
HEAVIEST SNOW WILL SHIFT NORTH OF I-70 BEFORE SLIDING BACK TO THE
SOUTH/EAST IN THE 06-12Z TIME PERIOD. WHILE 1/4SM HEAVY SNOW MAY
CONTINUE THROUGH THIS TIME...FORCING ALOFT IS GRADUALLY WEAKENING
WITH THE STORM SHIFTING TO THE EAST. WILL CARRY 1/2SM AND MODERATE
SNOW THROUGH THE PERIOD AND LET LATER SHIFTS DETERMINE ADDITIONAL
CHANGES AS CONDITIONS EVOLVE OVERNIGHT. SNOW WILL DIMINISH IN
COVERAGE AND INTENSITY FROM NORTHWEST TO SOUTHEAST THROUGH EARLY
MONDAY AFTERNOON...BUT REMAIN ACROSS THE REGION THROUGHOUT THE
DAY. MAINTAIN IFR CONDITIONS THROUGH 18Z MONDAY. NORTHEAST WINDS
THIS AFTERNOON WILL BACK TO NORTHERLY THIS EVENING...THEN N/NW LATE
TONIGHT INTO MONDAY. GUSTS AT 25 TO 30KTS ARE POSSIBLE THROUGHOUT
THE PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL NOON EDT MONDAY FOR INZ021-028>031-
035>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...MK
NEAR TERM...CP
SHORT TERM...MK
LONG TERM....RYAN
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
126 PM EDT SUN MAR 24 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 322 AM EDT SUN MAR 24 2013
A STRENGTHENING LOW PRESSURE SYSTEM WILL LIFT NORTHEAST ACROSS
EASTERN KENTUCKY TODAY AND THIS EVENING BEFORE MOVING INTO SOUTHERN
OHIO OVERNIGHT. THIS SYSTEM IS EXPECTED TO BRING SIGNIFICANT WET
SNOW ACCUMULATION TO CENTRAL INDIANA ESPECIALLY CONSIDERING IT IS
LATE MARCH. SNOW ACCUMULATION WILL BE HEAVIEST LATE THIS AFTERNOON
AND TONIGHT. SCATTERED SNOW SHOWERS WILL LINGER BEFORE HIGH PRESSURE
GRADUALLY BUILDS IN FROM THE PLAINS BRINGING DRY WEATHER AND
GRADUALLY WARMING TEMPERATURES THROUGH LATE WEEK. BY
SATURDAY...HIGHS COULD BE NEAR NORMAL MOSTLY IN THE 50S WITH RAIN
SHOWER CHANCES IN SOUTHERLY FLOW ON THE BACK SIDE OF HIGH PRESSURE.
&&
.NEAR TERM /REST OF TODAY AND TONIGHT/...
ISSUED AT 1026 AM EDT SUN MAR 24 2013
AT 10 AM LOW PRESSURE OF JUST UNDER 1000 MB WAS CENTERED NEAR THE
MISSOURI BOOT HEEL. RADAR SHOWS MOST SNOWFALL HAS ENDED MOMENTARILY
ACROSS CENTRAL INDIANA WITH MODERATE TO HEAVY SNOW ACROSS WESTERN
AND SOUTHERN ILLINOIS AND RAIN SOUTH OF THERE. SLEET HAS ALSO BEEN
REPORTED WITHIN THE PAST COUPLE HOURS. TEMPERATURES IN THE AREA
RANGE FROM THE UPPER 20S IN THE NORTHEAST TO THE MIDDLE 30S ACROSS
THE SOUTH.
FOR THE UPDATE LEANED HEAVILY ON HRRR FOR TIMING OF RETURN OF
PRECIP BUT SPED UP BY A COUPLE HOURS BASED ON COMPARISON WITH
CURRENT RADAR ECHOES. WITH TRACK OF 6Z NAM JUMPING NORTH AND RAP
OVERDOING WARM INTRUSION COMPARED TO OBSERVATIONS USED SREFS AND
GFS FORECAST SOUNDINGS FOR PRECIP TYPE. ADDED SOME TIMING TO THE
POPS FOR THE REST OF THE DAY TO INDICATE A LULL IN ACTIVITY DURING
THE MORNING WITH POPS RAPIDLY INCREASING FROM THE WEST IN THE 11
AM TO NOON TIME FRAME AND OVERSPREADING THE AREA FROM THERE.
FORECAST SOUNDINGS INDICATE SOME POTENTIAL FOR SLEET TO MIX IN AS
FAR NORTH AS THE I-70 CORRIDOR SO ADDED A CHANCE FOR SLEET THERE
THROUGH MUCH OF THE AFTERNOON. MAINTAINED A MIX OF RAIN AND SNOW
IN THE SOUTH WITH THE AFOREMENTIONED SLEET POTENTIAL. SOUNDINGS
INDICATE A CHANGEOVER TO ALL SNOW BY AROUND 22-23Z. SOME CONCERN
THAT MIX OF RAIN AND SLEET WITH THE SNOW COULD DROP SNOWFALL
ACCUMULATION IN THE SOUTH DURING THE TODAY PERIOD BY A DECENT
AMOUNT...BUT THIS IS COUNTERACTED BY SIGNIFICANT SNOWFALL RATES
UPSTREAM IN SOUTHWESTERN AND CENTRAL ILLINOIS OF 1-3 INCHES PER
HOUR AND THUS MAKING NO APPRECIABLE CHANGES TO SNOWFALL AMOUNTS AT
THIS TIME. WITH OBSERVATIONS OF A FEW LIGHTNING STRIKES UPSTREAM
AND SYSTEM ONLY PROGGED TO STRENGTHEN AS IT ARRIVES ADDED A
SLIGHT CHANCE FOR THUNDER SOUTH OF INTERSTATE 70 AS WELL.
PREVIOUS DISCUSSION FOLLOWS...
MAIN CHALLENGE TODAY WILL BE PRECIPITATION TIMING AND TYPE
ALONG WITH SNOW AMOUNTS AS MODELS ARE NOW COMING TOGETHER NICELY
IN HANDLING THE STRENGTH AND LOCATION OF LOW PRESSURE SYSTEM THAT
IS PROGGED TO LIFT NORTHEAST FROM THE SOUTHERN STATES TO EAST
CENTRAL KENTUCKY BY 00Z MONDAY. STRONG UPPER LOW MOVING TO NEAR THE
CONFLUENCE OF THE OHIO AND MISSISSIPPI RIVERS ALONG WITH A VIGOROUS
140 PLUS KNOT JET ACROSS THE TENNESSEE VALLEY WILL RESULT IN THE
AFOREMENTIONED SURFACE LOW DEEPENING TO LESS THAN 995 MILLIBARS BY
EVENING AND RESULT IN MODERATE TO HEAVY SNOW BY LATE AFTERNOON.
WITH MODELS TRENDING A LITTLE BIT FURTHER SOUTH THAN PREVIOUS
RUNS...HEAVIEST SNOW TODAY SHOULD BE ALONG AND SOUTH OF INTERSTATE
70 AND TO THE NORTH OF THE MIXED AREA. THIS AREA WILL ALSO BE NEAR
ELONGATED 850 MILLIBAR FRONTOGENESIS AND INSTABILITY ALOFT THAT
COULD AID IN SNOW AMOUNTS...ALTHOUGH SNOW RATIOS WILL BE ON THE LOW
SIDE UNTIL LATE IN THE DAY WHEN THE COLUMN COOLS FURTHER AS THE LOW
MOVES INTO SOUTHERN OHIO. AT THIS POINT...STRONG DYNAMICS INCLUDING
QVECTOR CONVERGENCE FROM 850-500 MILLIBARS ALONG WITH
FRONTOGENETICAL FORCING...DIFFLUENT FLOW ALOFT AND INSTABILITY
ALOFT SHOULD RESULT IN MODERATE TO HEAVY SNOW WITH BANDING PRODUCING
THE HIGHEST AMOUNTS.
SNOWFALL AMOUNTS WILL CONTINUE TO BE TRICKY...WITH THE GROUND AND
SURFACE TEMPERATURES STARTING OFF ABOVE FREEZING WHICH SHOULD LOWER
SNOW AMOUNTS FROM WHAT EARLIER MODEL RUNS HAD...UPWARDS OF 12 INCHES
IN THE HEAVIEST SNOW BAND. BUFKIT SUGGESTS THIS SCENARIO ALONG WITH
DECENT COMPACTION OF THE SNOW. ALSO...EXACT AREA OF PROLONGED
BANDING STILL UP IN THE AIR...HOWEVER A WIDESPREAD 6 INCH STORM
TOTAL SNOW AMOUNT LOOKS GOOD THROUGH MONDAY MORNING WITH 10 INCH
AMOUNTS AND LOCALLY HIGHER NEAR THE DEFORMATION ZONE WHICH SHOULD BE
FAIRLY CLOSE TO EITHER SIDE OF THE INTERSTATE 70 CORRIDOR AND A BIT
FURTHER NORTH OF THE LATE AFTERNOON HEAVY SNOW. WITH MODEL LOW
TRACKS AND RESULTANT SNOWFALL ACCUMULATION A LITTLE FURTHER
SOUTH...WILL UPGRADE THE SOUTHERNMOST TIER TO A WINTER STORM WARNING
AND KEEP THE WARNING GOING ELSEWHERE THROUGH NOON EDT MONDAY.
POPS WILL INCREASE TO OCCASIONAL FROM SOUTHWEST TO NORTHEAST TODAY
WITH MOST OR ALL OF CENTRAL INDIANA SEEING PRECIPITATION BY 18Z.
POPS WILL ONLY DROP SLIGHTLY TO LIKELY TOWARD MORNING.
COULD ALSO SEE SOME BLOWING SNOW TODAY AS BUFKIT SUGGESTS GUSTS TO
30 MPH OR MORE.
WITH THICK CLOUDS AROUND TODAY ALONG WITH EVAPORATIVE
COOLING...COLDER NAM MOS AND ALLBLEND TEMPERATURES IN THE
LOWER 30S NORTH TO THE MID 30S SOUTH LOOK GOOD.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 322 AM EDT SUN MAR 24 2013
MODELS AGREE THAT THROUGH THEIR QPF FIELDS THAT THE SNOW WILL BE
WINDING DOWN ON MONDAY WITH ONLY LINGERING SMALL SNOW SHOWER CHANCES
THROUGH TUESDAY. FINALLY...COULD SEE SOME CLEARING AND THE COLDEST
TEMPERATURES OF THE WEEK TUESDAY NIGHT WITH THE SNOW PACK SERVING TO
MAXIMIZE RADIATIONAL HEAT LOSS TO SPACE.
AFTERNOON TEMPERATURES WILL BE WELL BELOW NORMAL WITH THE
SNOW...NORTHWEST WINDS AND CLOUD COVER.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
ISSUED AT 355 AM EDT SUN MAR 24 2013
THE LONG TERM PERIOD WILL START OUT WITH HIGH PRESSURE AT THE
SURFACE AND RIDGING ALOFT. AS A RESULT...DRY CONDITIONS WILL
PREVAIL INTO FRIDAY. HOWEVER...LATEST REGIONAL INITIALIZATION
STILL WANTS TO BRING SLIGHT CHANCES FOR PRECIP INTO CENTRAL
INDIANA ON FRIDAY AND SATURDAY DUE TO A VERY SUBTLE WAVE IN THE
UPPER FLOW. AT THIS TIME...HAVE NOT SEEN ENOUGH CONSISTENCY IN
MODELS TO DIVERT FROM THAT FORECAST...SO WILL KEEP THE POPS WITH
LATEST INITIALIZATION. A SLIGHT WARMING TREND THROUGH THE EXTENDED
PERIOD WOULD KEEP ANY PRECIP THAT FALLS IN THE FORM OF RAIN.
&&
.AVIATION /DISCUSSION FOR 241800Z TAF ISSUANCE/...
ISSUED AT 126 PM EDT SUN MAR 24 2013
CONDITIONS WILL RAPIDLY DETERIORATE LATE THIS AFTERNOON TO VLIFR
WITHIN HEAVY SNOW. IFR AND LOWER CONDITIONS WILL PERSIST INTO
MONDAY AFTERNOON.
CENTRAL INDIANA REMAINS WITHIN A DRY SLOT IN THE WAKE OF THE
MORNING SNOW. THE CALM BEFORE THE STORM IF YOU WILL AS HEAVY
PRECIP MOVING EAST ACROSS ILLINOIS AHEAD OF A DEEPENING LOW
PRESSURE. LOW LEVEL THERMAL ANALYSIS STILL SHOWING A WARM PUNCH
ALOFT MOVING ACROSS THE SOUTHERN HALF OF THE FORECAST AREA OVER
THE NEXT 3-4 HOURS BEFORE 850MB TEMPS CRASH. THIS IS LIKELY TO
ENABLE A PERIOD OF MIXING WITH RAIN...SLEET AND SNOW AT KBMG
BEGINNING AROUND OR SHORTLY AFTER 20Z. MAY EVEN SEE A BIT OF SLEET
MIX AT KIND IN THE 20-21Z TIME PERIOD. ANY MIXING WILL BE SHORT-
LIVED HOWEVER AS EVAPORATIVE COOLING TAKES PLACE THROUGH THE
BOUNDARY LAYER...WITH PRECIP CHANGING TO ALL SNOW AT BOTH KIND AND
KBMG AFTER 21Z.
SNOW WILL BECOME HEAVY BY EARLY EVENING AT ALL TERMINALS AS AXIS
OF DEEPEST FORCING WITH A STRONG WELL DEVELOPED TROWAL SETS UP IN
THE VICINITY OF THE I-70 CORRIDOR. CONSIDERING REPORTS TO THE WEST
OVER MISSOURI AND ILLINOIS AND THE ANTICIPATION THAT THE LOW
STRENGTHENS FURTHER AS IT MOVES INTO THE REGION THIS EVENING...
EXPECT A 3-6 HOUR PERIOD OF VERY HEAVY SNOWFALL WITH VISIBILITIES
AT OR UNDER 1/4SM. CONVECTIVE POTENTIAL AS WELL THROUGH THE
EVENING...ENHANCING SNOWFALL RATES WITHIN ANY THUNDERSNOW. HAVE
LEFT OUT ANY CB MENTION AT THIS TIME...BUT GREATEST POTENTIAL FOR
THUNDERSNOW WILL BE WITHIN THE HEAVIEST SNOWFALL DURING THE
EVENING.
HEAVIEST SNOW WILL SHIFT NORTH OF I-70 BEFORE SLIDING BACK TO THE
SOUTH/EAST IN THE 06-12Z TIME PERIOD. WHILE 1/4SM HEAVY SNOW MAY
CONTINUE THROUGH THIS TIME...FORCING ALOFT IS GRADUALLY WEAKENING
WITH THE STORM SHIFTING TO THE EAST. WILL CARRY 1/2SM AND MODERATE
SNOW THROUGH THE PERIOD AND LET LATER SHIFTS DETERMINE ADDITIONAL
CHANGES AS CONDITIONS EVOLVE OVERNIGHT. SNOW WILL DIMINISH IN
COVERAGE AND INTENSITY FROM NORTHWEST TO SOUTHEAST THROUGH EARLY
MONDAY AFTERNOON...BUT REMAIN ACROSS THE REGION THROUGHOUT THE
DAY. MAINTAIN IFR CONDITIONS THROUGH 18Z MONDAY. NORTHEAST WINDS
THIS AFTERNOON WILL BACK TO NORTHERLY THIS EVENING...THEN N/NW LATE
TONIGHT INTO MONDAY. GUSTS AT 25 TO 30KTS ARE POSSIBLE THROUGHOUT
THE PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL NOON EDT MONDAY FOR INZ021-028>031-
035>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...MK
NEAR TERM...CP
SHORT TERM...MK
LONG TERM....TDUD
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1036 AM EDT SUN MAR 24 2013
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 322 AM EDT SUN MAR 24 2013
A STRENGTHENING LOW PRESSURE SYSTEM WILL LIFT NORTHEAST ACROSS
EASTERN KENTUCKY TODAY AND THIS EVENING BEFORE MOVING INTO SOUTHERN
OHIO OVERNIGHT. THIS SYSTEM IS EXPECTED TO BRING SIGNIFICANT WET
SNOW ACCUMULATION TO CENTRAL INDIANA ESPECIALLY CONSIDERING IT IS
LATE MARCH. SNOW ACCUMULATION WILL BE HEAVIEST LATE THIS AFTERNOON
AND TONIGHT. SCATTERED SNOW SHOWERS WILL LINGER BEFORE HIGH PRESSURE
GRADUALLY BUILDS IN FROM THE PLAINS BRINGING DRY WEATHER AND
GRADUALLY WARMING TEMPERATURES THROUGH LATE WEEK. BY
SATURDAY...HIGHS COULD BE NEAR NORMAL MOSTLY IN THE 50S WITH RAIN
SHOWER CHANCES IN SOUTHERLY FLOW ON THE BACK SIDE OF HIGH PRESSURE.
&&
.NEAR TERM /REST OF TODAY AND TONIGHT/...
ISSUED AT 1026 AM EDT SUN MAR 24 2013
AT 10 AM LOW PRESSURE OF JUST UNDER 1000 MB WAS CENTERED NEAR THE
MISSOURI BOOT HEEL. RADAR SHOWS MOST SNOWFALL HAS ENDED MOMENTARILY
ACROSS CENTRAL INDIANA WITH MODERATE TO HEAVY SNOW ACROSS WESTERN
AND SOUTHERN ILLINOIS AND RAIN SOUTH OF THERE. SLEET HAS ALSO BEEN
REPORTED WITHIN THE PAST COUPLE HOURS. TEMPERATURES IN THE AREA
RANGE FROM THE UPPER 20S IN THE NORTHEAST TO THE MIDDLE 30S ACROSS
THE SOUTH.
FOR THE UPDATE LEANED HEAVILY ON HRRR FOR TIMING OF RETURN OF
PRECIP BUT SPED UP BY A COUPLE HOURS BASED ON COMPARISON WITH
CURRENT RADAR ECHOES. WITH TRACK OF 6Z NAM JUMPING NORTH AND RAP
OVERDOING WARM INTRUSION COMPARED TO OBSERVATIONS USED SREFS AND
GFS FORECAST SOUNDINGS FOR PRECIP TYPE. ADDED SOME TIMING TO THE
POPS FOR THE REST OF THE DAY TO INDICATE A LULL IN ACTIVITY DURING
THE MORNING WITH POPS RAPIDLY INCREASING FROM THE WEST IN THE 11
AM TO NOON TIME FRAME AND OVERSPREADING THE AREA FROM THERE.
FORECAST SOUNDINGS INDICATE SOME POTENTIAL FOR SLEET TO MIX IN AS
FAR NORTH AS THE I-70 CORRIDOR SO ADDED A CHANCE FOR SLEET THERE
THROUGH MUCH OF THE AFTERNOON. MAINTAINED A MIX OF RAIN AND SNOW
IN THE SOUTH WITH THE AFOREMENTIONED SLEET POTENTIAL. SOUNDINGS
INDICATE A CHANGEOVER TO ALL SNOW BY AROUND 22-23Z. SOME CONCERN
THAT MIX OF RAIN AND SLEET WITH THE SNOW COULD DROP SNOWFALL
ACCUMULATION IN THE SOUTH DURING THE TODAY PERIOD BY A DECENT
AMOUNT...BUT THIS IS COUNTERACTED BY SIGNIFICANT SNOWFALL RATES
UPSTREAM IN SOUTHWESTERN AND CENTRAL ILLINOIS OF 1-3 INCHES PER
HOUR AND THUS MAKING NO APPRECIABLE CHANGES TO SNOWFALL AMOUNTS AT
THIS TIME. WITH OBSERVATIONS OF A FEW LIGHTNING STRIKES UPSTREAM
AND SYSTEM ONLY PROGGED TO STRENGTHEN AS IT ARRIVES ADDED A
SLIGHT CHANCE FOR THUNDER SOUTH OF INTERSTATE 70 AS WELL.
PREVIOUS DISCUSSION FOLLOWS...
MAIN CHALLENGE TODAY WILL BE PRECIPITATION TIMING AND TYPE
ALONG WITH SNOW AMOUNTS AS MODELS ARE NOW COMING TOGETHER NICELY
IN HANDLING THE STRENGTH AND LOCATION OF LOW PRESSURE SYSTEM THAT
IS PROGGED TO LIFT NORTHEAST FROM THE SOUTHERN STATES TO EAST
CENTRAL KENTUCKY BY 00Z MONDAY. STRONG UPPER LOW MOVING TO NEAR THE
CONFLUENCE OF THE OHIO AND MISSISSIPPI RIVERS ALONG WITH A VIGOROUS
140 PLUS KNOT JET ACROSS THE TENNESSEE VALLEY WILL RESULT IN THE
AFOREMENTIONED SURFACE LOW DEEPENING TO LESS THAN 995 MILLIBARS BY
EVENING AND RESULT IN MODERATE TO HEAVY SNOW BY LATE AFTERNOON.
WITH MODELS TRENDING A LITTLE BIT FURTHER SOUTH THAN PREVIOUS
RUNS...HEAVIEST SNOW TODAY SHOULD BE ALONG AND SOUTH OF INTERSTATE
70 AND TO THE NORTH OF THE MIXED AREA. THIS AREA WILL ALSO BE NEAR
ELONGATED 850 MILLIBAR FRONTOGENESIS AND INSTABILITY ALOFT THAT
COULD AID IN SNOW AMOUNTS...ALTHOUGH SNOW RATIOS WILL BE ON THE LOW
SIDE UNTIL LATE IN THE DAY WHEN THE COLUMN COOLS FURTHER AS THE LOW
MOVES INTO SOUTHERN OHIO. AT THIS POINT...STRONG DYNAMICS INCLUDING
QVECTOR CONVERGENCE FROM 850-500 MILLIBARS ALONG WITH
FRONTOGENTICAL FORCING...DIFFLUENT FLOW ALOFT AND INSTABILITY
ALOFT SHOULD RESULT IN MODERATE TO HEAVY SNOW WITH BANDING PRODUCING
THE HIGHEST AMOUNTS.
SNOWFALL AMOUNTS WILL CONTINUE TO BE TRICKY...WITH THE GROUND AND
SURFACE TEMPERATURES STARTING OFF ABOVE FREEZING WHICH SHOULD LOWER
SNOW AMOUNTS FROM WHAT EARLIER MODEL RUNS HAD...UPWARDS OF 12 INCHES
IN THE HEAVIEST SNOW BAND. BUFKIT SUGGESTS THIS SCENARIO ALONG WITH
DECENT COMPACTION OF THE SNOW. ALSO...EXACT AREA OF PROLONGED
BANDING STILL UP IN THE AIR...HOWEVER A WIDESPREAD 6 INCH STORM
TOTAL SNOW AMOUNT LOOKS GOOD THROUGH MONDAY MORNING WITH 10 INCH
AMOUNTS AND LOCALLY HIGHER NEAR THE DEFORMATION ZONE WHICH SHOULD BE
FAIRLY CLOSE TO EITHER SIDE OF THE INTERSTATE 70 CORRIDOR AND A BIT
FURTHER NORTH OF THE LATE AFTERNOON HEAVY SNOW. WITH MODEL LOW
TRACKS AND RESULTANT SNOWFALL ACCUMULATION A LITTLE FURTHER
SOUTH...WILL UPGRADE THE SOUTHERNMOST TIER TO A WINTER STORM WARNING
AND KEEP THE WARNING GOING ELSEWHERE THROUGH NOON EDT MONDAY.
POPS WILL INCREASE TO OCCASIONAL FROM SOUTHWEST TO NORTHEAST TODAY
WITH MOST OR ALL OF CENTRAL INDIANA SEEING PRECIPITATION BY 18Z.
POPS WILL ONLY DROP SLIGHTLY TO LIKELY TOWARD MORNING.
COULD ALSO SEE SOME BLOWING SNOW TODAY AS BUFKIT SUGGESTS GUSTS TO
30 MPH OR MORE.
WITH THICK CLOUDS AROUND TODAY ALONG WITH EVAPORATIVE
COOLING...COLDER NAM MOS AND ALLBLEND TEMPERATURES IN THE
LOWER 30S NORTH TO THE MID 30S SOUTH LOOK GOOD.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 322 AM EDT SUN MAR 24 2013
MODELS AGREE THAT THROUGH THEIR QPF FIELDS THAT THE SNOW WILL BE
WINDING DOWN ON MONDAY WITH ONLY LINGERING SMALL SNOW SHOWER CHANCES
THROUGH TUESDAY. FINALLY...COULD SEE SOME CLEARING AND THE COLDEST
TEMPERATURES OF THE WEEK TUESDAY NIGHT WITH THE SNOW PACK SERVING TO
MAXIMIZE RADIATIONAL HEAT LOSS TO SPACE.
AFTERNOON TEMPERATURES WILL BE WELL BELOW NORMAL WITH THE
SNOW...NORTHWEST WINDS AND CLOUD COVER.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
ISSUED AT 355 AM EDT SUN MAR 24 2013
THE LONG TERM PERIOD WILL START OUT WITH HIGH PRESSURE AT THE
SURFACE AND RIDGING ALOFT. AS A RESULT...DRY CONDITIONS WILL
PREVAIL INTO FRIDAY. HOWEVER...LATEST REGIONAL INITIALIZATION
STILL WANTS TO BRING SLIGHT CHANCES FOR PRECIP INTO CENTRAL
INDIANA ON FRIDAY AND SATURDAY DUE TO A VERY SUBTLE WAVE IN THE
UPPER FLOW. AT THIS TIME...HAVE NOT SEEN ENOUGH CONSISTENCY IN
MODELS TO DIVERT FROM THAT FORECAST...SO WILL KEEP THE POPS WITH
LATEST INITIALIZATION. A SLIGHT WARMING TREND THROUGH THE EXTENDED
PERIOD WOULD KEEP ANY PRECIP THAT FALLS IN THE FORM OF RAIN.
&&
.AVIATION /DISCUSSION FOR THE 241500Z TAF UPDATE/...
ISSUED AT 1021 AM EDT SUN MAR 24 2013
INITIAL BURST OF SNOW HAS MADE IT THROUGH THE REGION AND IS NOW TO
THE EAST OF ALL TERMINALS AS OF 14Z. HAVE SEEN POCKETS OF MVFR WITH
POCKETS OF IFR CONDITIONS IN THE WAKE OF THE EARLY MORNING SNOW. ALL
EYES ARE QUICKLY TURNING TO ROUND 2 OF THE STORM...WITH HEAVY SNOW
MAKING ITS WAY EAST ACROSS MISSOURI AND INTO WESTERN ILLINOIS. RAPID
REFRESH HAS A NICE HANDLE ON THE PRECIP SHIELD BUT APPEARS TO BE
RUNNING A FEW HOURS SLOWER THAN WHAT IS CURRENTLY ONGOING.
HAVE MADE SOME ADJUSTMENTS AS A RESULT IN TIMING THE ONSET OF THE
PRECIP RETURN...LIKELY TO BEGIN IMPACTING ALL TERMINALS BETWEEN
17-20Z. MOST CURRENT LOW LEVEL THERMAL ANALYSIS IS NOW SUGGESTING
POTENTIAL FOR A PERIOD ON THE ORDER OF AN HOUR OR TWO WHERE SLEET
MAY MANAGE TO MIX WITH SNOW AT KIND...AND RAIN/SLEET MIXING WITH
SNOW AT KBMG AS THE AXIS OF WARMER AIR ALOFT PASSES THROUGH. AT KHUF
AND KLAF...EXPECT PRECIP AS ALL SNOW THIS AFTERNOON. AFTER
20-21Z...PRECIP SHOULD SWITCH BACK TO ALL SNOW AT KBMG AND KIND AS
COLDER AIR ADVECTS INTO THE REGION. SNOW IS LIKELY TO BECOME HEAVY
BY LATE AFTERNOON BASED ON OBS BACK TO OUR WEST. MAY ACTUALLY BE A
TOUCH CONSERVATIVE WITH RESPECT TO VISIBILITIES/CEILINGS AS
POTENTIAL WITHIN HEAVIER BANDS BY THIS EVENING FOR 1/4SM. WILL
ADDRESS IN GREATER DETAIL FOR THE 18Z FORECAST.
12Z DISCUSSION FOLLOWS.
SNOW WILL AFFECT TAF SITES IN 2 WAVES...BUT TRYING TO TIME THAT
BREAK IN THE SNOW IS POSING TO BE A CHALLENGE. SO FAR...THE TREND
HAS BEEN FOR CONDITIONS TO ABRUPTLY DROP TO IFR CATEGORY WITH THE
ONSET OF PRECIP. THERE WAS A BRIEF PERIOD OF RAIN/SNOW MIX AT KIND AT
INITIAL ONSET...BUT IT QUICKLY TRANSITIONED TO SNOW. EXPECT SNOW
FROM THIS POINT ON AT ALL TAF SITES. THE FIRST WAVE OF SNOW HAS
ALREADY ENDED AT KHUF...BUT SHOULD RESUME ONCE AGAIN BY LATE
MORNING. THE SAME TREND SHOULD OCCUR AT REMAINING TAF SITES WITHIN
THE NEXT HOUR OR 2 AND THEN RESUME AGAIN BY EARLY AFTERNOON AT
THOSE SITES AS WELL. SO...IMPROVED CONDITIONS TO MVFR CATEGORY DURING
THAT BRIEF WINDOW OF DRY CONDITIONS AT ALL TAF SITES...AND THEN
EXPECT THEM TO DETERIORATE QUICKLY TO IFR ONCE AGAIN WITH THE NEXT
WAVE OF SNOW. SNOW WILL IMPACT TAFS THROUGH THE REMAINDER OF TAF
PERIOD WITH IFR/LIFR BEING THE PREVAILING FLIGHT CATEGORY DURING
SECOND WAVE OF SNOW.
WINDS WILL STRENGTHEN WITHIN THE NEXT FEW HOURS OUT OF THE
NORTHEAST WITH SUSTAINED SPEEDS OF 12 TO 15 KTS AND GUSTS UP TO
28 KTS. WINDS WILL REMAIN STRONG THROUGH TONIGHT BUT BECOME
NORTHWESTERLY AFTER MIDNIGHT. DUE TO THE HEAVY/WET NATURE OF THE
SNOW...DO NOT EXPECT BLOWING SNOW TO BE AN IMPACT.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL NOON EDT MONDAY FOR INZ021-028>031-
035>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...MK
NEAR TERM...CP
SHORT TERM...MK
LONG TERM....TDUD
AVIATION...TDUD/RYAN
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1252 PM CDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 923 AM CD /ISSUED 927 AM CDT SUN MAR 24 2013/
T SUN MAR 24 2013
A QUICK UPDATE SENT TO ADJUST PAST FALLEN SNOW TOTALS FROM
OVERNIGHT...WHICH NOW ARE CERTAIN TO HAVE BEEN 1 TO 3 INCHES FROM
EAST CENTRAL IOWA THROUGH WEST CENTRAL ILLINOIS. AFTER A MINOR
LULL IN SNOW EARLY THIS MORNING...WE ARE NOW SEEING A PUSH OF
RENEWED LIFT WHICH LOOKS TO AFFECT THE SOUTHERN 1/3 THIS MORNING.
THIS IS ALREADY CREATING HEAVY SNOW RATES IN OUR FAR SOUTH. SINCE
1/4 MILE HEAVY SNOW IS INTENSE ENOUGH NOT TO CARE ABOUT MARGINAL
TEMPERATURES VS LIGHT SNOW...OUR AMOUNT NEED TO BE RAISED. I AM
NOW GOING FOR DAYTIME ACCUMS OF 2 TO 4 INCHES IN THE SOUTH
1/3...WHICH WOULD TAKE EVENT TOTALS THROUGH 7 PM TONIGHT INTO THE
4 TO 7 RANGE. WHILE HIGH END ADVISORY AMOUNTS...THE REPORTED
AFFECTS IN THE SOUTH STILL SHOW WET ROADS...WITH SOME SLUSH...THUS
NO PLANS TO CHANGE HEADLINES ARE CONSIDERED AT THIS TIME.
FARTHER NORTH...MARGINAL TEMPS AND LIGHTER SNOWS SHOULD KEEP OUR
GOING FORECAST IN GOOD TRACK FOR NOW.
ERVIN
&&
.SYNOPSIS...
ISSUED AT 322 AM CDT SUN MAR 24 2013
06Z SFC ANALYSIS HAS THE LOW IN NORTHERN MISSISSIPPI WITH AN
INVERTED TROF INTO MISSOURI. ANOTHER TROF RAN FROM EASTERN MINNESOTA
INTO EASTERN IOWA. DEW POINTS WERE IN THE TEENS AND 20S OVER THE
GREAT LAKES AND MID MISSISSIPPI VALLEY WITH 30S AND HIGHER FROM THE
OHIO VALLEY ON SOUTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 322 AM CDT SUN MAR 24 2013
OVERALL AN INTERESTING SYSTEM. THE TRENDS OF BRINGING THE SYSTEM
NORTH HAVE ENDED UP BEING INCORRECT WITH THE MAIN LOW PASSING WELL
SOUTH OF THE AREA.
SATELLITE/RADAR SHOWS A BREAK IN THE SNOW ACROSS NORTHERN MISSOURI
BUT RAP TRENDS AND RECENT WATER VAPOR TRENDS INDICATE THIS BREAK IN
THE SNOW IS FILLING. THE WAA TOOL INDICATES THE BETTER SNOW WILL BE
ACROSS THE SOUTH IN THE HEADLINE AREA. HOWEVER...TEMPERATURES AT OR
JUST BELOW FREEZING IS ALLOWING SOME MELTING TO OCCUR WITH
ACCUMULATIONS BEING ON ELEVATED SURFACES. PAVEMENT TEMPERATURES ARE
AT OR ABOVE FREEZING SO MELTING IS OCCURRING THERE AS WELL.
SO...WILL CONTINUE WITH THE CURRENT HEADLINES AS IS. THE HWY 20
CORRIDOR HAS NOT YET SEEN ANY SNOW BUT THAT SHOULD CHANGE THIS
MORNING AS THE NEXT ROUND OF FORCING MOVES INTO THE AREA. INDIRECT
SOLAR INSOLATION WILL HELP PUSH TEMPERATURES ABOVE FREEZING DURING
THE DAY SO ADDITIONAL MELTING AND COMPACTION WILL OCCUR.
THE FURTHER SOUTH PASSAGE OF THE SYSTEM AND WARM TEMPERATURES WILL
HELP SUPPRESS OVERALL SNOWFALL AMOUNTS. IN THE ADVISORY AREA THE
EXTREME SOUTH PART OF THE CWFA SHOULD SEE 3-4 INCHES BY EVENING WITH
1-2 BY THE TIME ONE REACHES THE I-80 CORRIDOR. NORTH OF HWY 30
AMOUNTS SHOULD BE APPROACHING AN INCH.
TONIGHT...LIGHT SNOW WILL CONTINUE WITH IT ENDING ACROSS THE
NORTHERN THIRD OF THE CWFA AFTER MIDNIGHT. SOUTH OF A KOTM TO KGBG
LINE AMOUNTS AROUND OR JUST OVER AN INCH ARE EXPECTED WITH NOT QUITE
AN INCH AROUND THE I-80 CORRIDOR. NORTH OF HWY 30 A DUSTING TO ONE
HALF INCH IS EXPECTED. ..08..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 322 AM CDT SUN MAR 24 2013
LIGHT SNOW TO EXIT FAR SOUTHERN COUNTIES MON AM WITH PASSAGE
OF ELONGATED WEST-EAST UPPER TROUGH ON BACKSIDE OF OHIO VLY
SHORTWAVE. FEW FLURRIES MAY LINGER ACROSS ENTIRE AREA MON
WITH CYCLONIC FLOW AND COLD ADVECTION. 925 MB TEMPS AROUND
-5C SUPPORTS HIGHS MAINLY IN THE MIDDLE 30S. MON NGT... WITH
CONTINUED COLD ADVECTION AND CYCLONIC FLOW EXPECT PARTLY TO
MOSTLY CLOUDY SKIES AND THUS STAYED NEAR OR JUST ABOVE WARM
SIDE OF GUIDANCE ON LOWS. HOWEVER... AS CLOUDS GO SO GO THE
LOW TEMPS AND WILL NEED TO WATCH FOR POSSIBLY MORE CLEARING
AND COLDER LOWS WITH SOME SUGGESTION OF WEAK MID/UPPER LEVEL
RIDGING IN WAKE OF UPPER TROUGH.
TUE-TUE NGT... CYCLONIC FLOW TO KEEP AT LEAST PARTLY CLOUDY
SKIES TUE ESPECIALLY EASTERN 1/3-1/2... WITH ONLY SLIGHT
MODERATION ON TEMPS BY 1-3 DEGS FROM THOSE OF MON. CANT RULE
OUT FEW FLURRIES OR EVEN BRIEF SNOW SHOWER FAR EAST WITH
ENOUGH HEATING AS MODELS DEPICT WEAK ENERGY ROTATING DOWN
THROUGH WI AND NORTHERN IL TUE PM. PARTLY CLOUDY TO MOSTLY
CLEAR SKIES EXPECTED TUE NGT WITH SFC RIDGE AXIS BUILDING IN.
LOWS MAINLY UPPER TEENS TO LOWER 20S... BUT IF WINDS SHOULD
GO LIGHT FOR ANY LENGTH OF TIME THEN COULD SEE MINS AS COLD AS
AROUND 14-17 DEGS ESPECIALLY WEST/SOUTHWEST SECTIONS BEING IN
CLOSE PROXIMITY TO RIDGE AXIS.
WED-SAT... OVERALL MODERATING TEMPS LOOK TO BE IN STORE DURING
THE PERIOD... WITH TEMPS EDGING NEAR NORMAL TOWARD THE
END OF PERIOD AS THE PERSISTENT BLOCKING PATTERN OVER NORTH
AMERICA RESPONSIBLE FOR LOCKING IN THE COLD AIR IS SHOWN
TO BREAK DOWN. WITH THIS WARMING TREND WILL ALSO COME AT LEAST
SOME THREAT OF MAINLY LIGHT PRECIPITATION OVER THE LATTER HALF OF
THE WEEK BEING IN FAIRLY CLOSE PROXIMITY TO MID LEVEL BAROCLINIC
ZONE AND SUBJECT TO WEAK IMPULSES PROPAGATING DOWN IN NORTHWEST
FLOW ALOFT. CONSENSUS MODEL INTRODUCED SEVERAL PERIODS OF SLIGHT
CHC POPS FROM WED NGT THROUGH FRI... BUT GIVEN THE WEAK AND
VARYING SIGNAL FROM THE MODELS IT WAS COLLABORATED WITH
SURROUNDING OFFICES TO LOWER PRECIPITATION CHANCES BELOW MENTION
THROUGH FRI AND AWAIT FOR SOME BETTER CONSISTENCY. THE SIGNAL IS
STRONGER AND MORE CONSISTENT BY NEXT WEEKEND AND HAVE THEREFORE
LEFT IN PRECIPITATION CHCS BY SAT NGT. BEYOND THE SCOPE OF THE
EXTENDED... THE PATTERN REMAINS QUITE ACTIVE WITH THE MEDIUM RANGE
MODELS POINTING TO ANOTHER STORM SYSTEM POSSIBLY IMPACTING THE
AREA TOWARD THE MIDDLE PORTION OF THE FIRST WEEK OF APRIL WITH THE
POTENTIAL FOR AT LEAST MODERATE PRECIPITATION AMOUNTS WITH MAINLY
RAIN AND POSSIBLY SOME SNOW SUGGESTED. 05
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1248 PM CDT SUN MAR 24 2013
A SLOW MOVING STORM SYSTEM WILL BRING PERSISTENT LIGHT TO MODERATE
SNOW TO EASTERN IOWA AND ILLINOIS THROUGH LATE TONIGHT...THEN
FLURRIES THROUGH MONDAY. THIS WILL RESULT IN PERSISTENT MVFR/IFR
CONDITIONS TODAY THROUGH TONIGHT...WITH CIGS OF 1000 TO 2000 FT
COMMON...AND VISIBILITIES BETWEEN 1 AND 5 MILES COMMON. A PERIOD
OF 1/2 MILE VIS IN MODERATE SNOW IS EXPECTED TO AFFECT MLI AND BRL
OCCASIONALLY THROUGH 22Z TODAY. DURING THIS PERIOD...CIGS MAY ALSO
LOWER TO 500 FT AT TIMES. OVERNIGHT...GENERALLY 3 TO 6 MILE
VISIBILITIES ARE EXPECTED IN LIGHT SNOW AND FOG.
ERVIN
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR
IAZ087>089-098-099.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ025-
026-034-035.
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MOZ009-
010.
&&
$$
UPDATE...ERVIN
SHORT TERM...08
LONG TERM...05
AVIATION...ERVIN
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
927 AM CDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 923 AM CDT SUN MAR 24 2013
A QUICK UPDATE SENT TO ADJUST PAST FALLEN SNOW TOTALS FROM
OVERNIGHT...WHICH NOW ARE CERTAIN TO HAVE BEEN 1 TO 3 INCHES FROM
EAST CENTRAL IOWA THROUGH WEST CENTRAL ILLINOIS. AFTER A MINOR
LULL IN SNOW EARLY THIS MORNING...WE ARE NOW SEEING A PUSH OF
RENEWED LIFT WHICH LOOKS TO AFFECT THE SOUTHERN 1/3 THIS MORNING.
THIS IS ALREADY CREATING HEAVY SNOW RATES IN OUR FAR SOUTH. SINCE
1/4 MILE HEAVY SNOW IS INTENSE ENOUGH NOT TO CARE ABOUT MARGINAL
TEMPERATURES VS LIGHT SNOW...OUR AMOUNT NEED TO BE RAISED. I AM
NOW GOING FOR DAYTIME ACCUMS OF 2 TO 4 INCHES IN THE SOUTH
1/3...WHICH WOULD TAKE EVENT TOTALS THROUGH 7 PM TONIGHT INTO THE
4 TO 7 RANGE. WHILE HIGH END ADVISORY AMOUNTS...THE REPORTED
AFFECTS IN THE SOUTH STILL SHOW WET ROADS...WITH SOME SLUSH...THUS
NO PLANS TO CHANGE HEADLINES ARE CONSIDERED AT THIS TIME.
FARTHER NORTH...MARGINAL TEMPS AND LIGHTER SNOWS SHOULD KEEP OUR
GOING FORECAST IN GOOD TRACK FOR NOW.
ERVIN
&&
.SYNOPSIS...
ISSUED AT 322 AM CDT SUN MAR 24 2013
06Z SFC ANALYSIS HAS THE LOW IN NORTHERN MISSISSIPPI WITH AN
INVERTED TROF INTO MISSOURI. ANOTHER TROF RAN FROM EASTERN MINNESOTA
INTO EASTERN IOWA. DEW POINTS WERE IN THE TEENS AND 20S OVER THE
GREAT LAKES AND MID MISSISSIPPI VALLEY WITH 30S AND HIGHER FROM THE
OHIO VALLEY ON SOUTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 322 AM CDT SUN MAR 24 2013
OVERALL AN INTERESTING SYSTEM. THE TRENDS OF BRINGING THE SYSTEM
NORTH HAVE ENDED UP BEING INCORRECT WITH THE MAIN LOW PASSING WELL
SOUTH OF THE AREA.
SATELLITE/RADAR SHOWS A BREAK IN THE SNOW ACROSS NORTHERN MISSOURI
BUT RAP TRENDS AND RECENT WATER VAPOR TRENDS INDICATE THIS BREAK IN
THE SNOW IS FILLING. THE WAA TOOL INDICATES THE BETTER SNOW WILL BE
ACROSS THE SOUTH IN THE HEADLINE AREA. HOWEVER...TEMPERATURES AT OR
JUST BELOW FREEZING IS ALLOWING SOME MELTING TO OCCUR WITH
ACCUMULATIONS BEING ON ELEVATED SURFACES. PAVEMENT TEMPERATURES ARE
AT OR ABOVE FREEZING SO MELTING IS OCCURRING THERE AS WELL.
SO...WILL CONTINUE WITH THE CURRENT HEADLINES AS IS. THE HWY 20
CORRIDOR HAS NOT YET SEEN ANY SNOW BUT THAT SHOULD CHANGE THIS
MORNING AS THE NEXT ROUND OF FORCING MOVES INTO THE AREA. INDIRECT
SOLAR INSOLATION WILL HELP PUSH TEMPERATURES ABOVE FREEZING DURING
THE DAY SO ADDITIONAL MELTING AND COMPACTION WILL OCCUR.
THE FURTHER SOUTH PASSAGE OF THE SYSTEM AND WARM TEMPERATURES WILL
HELP SUPPRESS OVERALL SNOWFALL AMOUNTS. IN THE ADVISORY AREA THE
EXTREME SOUTH PART OF THE CWFA SHOULD SEE 3-4 INCHES BY EVENING WITH
1-2 BY THE TIME ONE REACHES THE I-80 CORRIDOR. NORTH OF HWY 30
AMOUNTS SHOULD BE APPROACHING AN INCH.
TONIGHT...LIGHT SNOW WILL CONTINUE WITH IT ENDING ACROSS THE
NORTHERN THIRD OF THE CWFA AFTER MIDNIGHT. SOUTH OF A KOTM TO KGBG
LINE AMOUNTS AROUND OR JUST OVER AN INCH ARE EXPECTED WITH NOT QUITE
AN INCH AROUND THE I-80 CORRIDOR. NORTH OF HWY 30 A DUSTING TO ONE
HALF INCH IS EXPECTED. ..08..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 322 AM CDT SUN MAR 24 2013
LIGHT SNOW TO EXIT FAR SOUTHERN COUNTIES MON AM WITH PASSAGE
OF ELONGATED WEST-EAST UPPER TROUGH ON BACKSIDE OF OHIO VLY
SHORTWAVE. FEW FLURRIES MAY LINGER ACROSS ENTIRE AREA MON
WITH CYCLONIC FLOW AND COLD ADVECTION. 925 MB TEMPS AROUND
-5C SUPPORTS HIGHS MAINLY IN THE MIDDLE 30S. MON NGT... WITH
CONTINUED COLD ADVECTION AND CYCLONIC FLOW EXPECT PARTLY TO
MOSTLY CLOUDY SKIES AND THUS STAYED NEAR OR JUST ABOVE WARM
SIDE OF GUIDANCE ON LOWS. HOWEVER... AS CLOUDS GO SO GO THE
LOW TEMPS AND WILL NEED TO WATCH FOR POSSIBLY MORE CLEARING
AND COLDER LOWS WITH SOME SUGGESTION OF WEAK MID/UPPER LEVEL
RIDGING IN WAKE OF UPPER TROUGH.
TUE-TUE NGT... CYCLONIC FLOW TO KEEP AT LEAST PARTLY CLOUDY
SKIES TUE ESPECIALLY EASTERN 1/3-1/2... WITH ONLY SLIGHT
MODERATION ON TEMPS BY 1-3 DEGS FROM THOSE OF MON. CANT RULE
OUT FEW FLURRIES OR EVEN BRIEF SNOW SHOWER FAR EAST WITH
ENOUGH HEATING AS MODELS DEPICT WEAK ENERGY ROTATING DOWN
THROUGH WI AND NORTHERN IL TUE PM. PARTLY CLOUDY TO MOSTLY
CLEAR SKIES EXPECTED TUE NGT WITH SFC RIDGE AXIS BUILDING IN.
LOWS MAINLY UPPER TEENS TO LOWER 20S... BUT IF WINDS SHOULD
GO LIGHT FOR ANY LENGTH OF TIME THEN COULD SEE MINS AS COLD AS
AROUND 14-17 DEGS ESPECIALLY WEST/SOUTHWEST SECTIONS BEING IN
CLOSE PROXIMITY TO RIDGE AXIS.
WED-SAT... OVERALL MODERATING TEMPS LOOK TO BE IN STORE DURING
THE PERIOD... WITH TEMPS EDGING NEAR NORMAL TOWARD THE
END OF PERIOD AS THE PERSISTENT BLOCKING PATTERN OVER NORTH
AMERICA RESPONSIBLE FOR LOCKING IN THE COLD AIR IS SHOWN
TO BREAK DOWN. WITH THIS WARMING TREND WILL ALSO COME AT LEAST
SOME THREAT OF MAINLY LIGHT PRECIPITATION OVER THE LATTER HALF OF
THE WEEK BEING IN FAIRLY CLOSE PROXIMITY TO MID LEVEL BAROCLINIC
ZONE AND SUBJECT TO WEAK IMPULSES PROPAGATING DOWN IN NORTHWEST
FLOW ALOFT. CONSENSUS MODEL INTRODUCED SEVERAL PERIODS OF SLIGHT
CHC POPS FROM WED NGT THROUGH FRI... BUT GIVEN THE WEAK AND
VARYING SIGNAL FROM THE MODELS IT WAS COLLABORATED WITH
SURROUNDING OFFICES TO LOWER PRECIPITATION CHANCES BELOW MENTION
THROUGH FRI AND AWAIT FOR SOME BETTER CONSISTENCY. THE SIGNAL IS
STRONGER AND MORE CONSISTENT BY NEXT WEEKEND AND HAVE THEREFORE
LEFT IN PRECIPITATION CHCS BY SAT NGT. BEYOND THE SCOPE OF THE
EXTENDED... THE PATTERN REMAINS QUITE ACTIVE WITH THE MEDIUM RANGE
MODELS POINTING TO ANOTHER STORM SYSTEM POSSIBLY IMPACTING THE
AREA TOWARD THE MIDDLE PORTION OF THE FIRST WEEK OF APRIL WITH THE
POTENTIAL FOR AT LEAST MODERATE PRECIPITATION AMOUNTS WITH MAINLY
RAIN AND POSSIBLY SOME SNOW SUGGESTED. 05
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 632 AM CDT SUN MAR 24 2013
IFR/MVFR CONDITIONS WILL CONTINUE THROUGH 00Z/25 WITH LIFR
CONDITIONS MOST PROBABLE AT KBRL AS THE STORM SYSTEM MOVES INTO
THE OHIO VALLEY. AFT 00Z/25 IFR/MVFR CONDITIONS WILL SLOWLY
IMPROVE TO MVFR AS SNOW INTENSITIES GRADUALLY DECREASE. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR
IAZ087>089-098-099.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ025-
026-034-035.
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MOZ009-
010.
&&
$$
UPDATE...ERVIN
SHORT TERM...08
LONG TERM...05
AVIATION...08
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
636 AM CDT SUN MAR 24 2013
.SYNOPSIS...
ISSUED AT 322 AM CDT SUN MAR 24 2013
06Z SFC ANALYSIS HAS THE LOW IN NORTHERN MISSISSIPPI WITH AN
INVERTED TROF INTO MISSOURI. ANOTHER TROF RAN FROM EASTERN MINNESOTA
INTO EASTERN IOWA. DEW POINTS WERE IN THE TEENS AND 20S OVER THE
GREAT LAKES AND MID MISSISSIPPI VALLEY WITH 30S AND HIGHER FROM THE
OHIO VALLEY ON SOUTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 322 AM CDT SUN MAR 24 2013
OVERALL AN INTERESTING SYSTEM. THE TRENDS OF BRINGING THE SYSTEM
NORTH HAVE ENDED UP BEING INCORRECT WITH THE MAIN LOW PASSING WELL
SOUTH OF THE AREA.
SATELLITE/RADAR SHOWS A BREAK IN THE SNOW ACROSS NORTHERN MISSOURI
BUT RAP TRENDS AND RECENT WATER VAPOR TRENDS INDICATE THIS BREAK IN
THE SNOW IS FILLING. THE WAA TOOL INDICATES THE BETTER SNOW WILL BE
ACROSS THE SOUTH IN THE HEADLINE AREA. HOWEVER...TEMPERATURES AT OR
JUST BELOW FREEZING IS ALLOWING SOME MELTING TO OCCUR WITH
ACCUMULATIONS BEING ON ELEVATED SURFACES. PAVEMENT TEMPERATURES ARE
AT OR ABOVE FREEZING SO MELTING IS OCCURRING THERE AS WELL.
SO...WILL CONTINUE WITH THE CURRENT HEADLINES AS IS. THE HWY 20
CORRIDOR HAS NOT YET SEEN ANY SNOW BUT THAT SHOULD CHANGE THIS
MORNING AS THE NEXT ROUND OF FORCING MOVES INTO THE AREA. INDIRECT
SOLAR INSOLATION WILL HELP PUSH TEMPERATURES ABOVE FREEZING DURING
THE DAY SO ADDITIONAL MELTING AND COMPACTION WILL OCCUR.
THE FURTHER SOUTH PASSAGE OF THE SYSTEM AND WARM TEMPERATURES WILL
HELP SUPPRESS OVERALL SNOWFALL AMOUNTS. IN THE ADVISORY AREA THE
EXTREME SOUTH PART OF THE CWFA SHOULD SEE 3-4 INCHES BY EVENING WITH
1-2 BY THE TIME ONE REACHES THE I-80 CORRIDOR. NORTH OF HWY 30
AMOUNTS SHOULD BE APPROACHING AN INCH.
TONIGHT...LIGHT SNOW WILL CONTINUE WITH IT ENDING ACROSS THE
NORTHERN THIRD OF THE CWFA AFTER MIDNIGHT. SOUTH OF A KOTM TO KGBG
LINE AMOUNTS AROUND OR JUST OVER AN INCH ARE EXPECTED WITH NOT QUITE
AN INCH AROUND THE I-80 CORRIDOR. NORTH OF HWY 30 A DUSTING TO ONE
HALF INCH IS EXPECTED. ..08..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 322 AM CDT SUN MAR 24 2013
LIGHT SNOW TO EXIT FAR SOUTHERN COUNTIES MON AM WITH PASSAGE
OF ELONGATED WEST-EAST UPPER TROUGH ON BACKSIDE OF OHIO VLY
SHORTWAVE. FEW FLURRIES MAY LINGER ACROSS ENTIRE AREA MON
WITH CYCLONIC FLOW AND COLD ADVECTION. 925 MB TEMPS AROUND
-5C SUPPORTS HIGHS MAINLY IN THE MIDDLE 30S. MON NGT... WITH
CONTINUED COLD ADVECTION AND CYCLONIC FLOW EXPECT PARTLY TO
MOSTLY CLOUDY SKIES AND THUS STAYED NEAR OR JUST ABOVE WARM
SIDE OF GUIDANCE ON LOWS. HOWEVER... AS CLOUDS GO SO GO THE
LOW TEMPS AND WILL NEED TO WATCH FOR POSSIBLY MORE CLEARING
AND COLDER LOWS WITH SOME SUGGESTION OF WEAK MID/UPPER LEVEL
RIDGING IN WAKE OF UPPER TROUGH.
TUE-TUE NGT... CYCLONIC FLOW TO KEEP AT LEAST PARTLY CLOUDY
SKIES TUE ESPECIALLY EASTERN 1/3-1/2... WITH ONLY SLIGHT
MODERATION ON TEMPS BY 1-3 DEGS FROM THOSE OF MON. CANT RULE
OUT FEW FLURRIES OR EVEN BRIEF SNOW SHOWER FAR EAST WITH
ENOUGH HEATING AS MODELS DEPICT WEAK ENERGY ROTATING DOWN
THROUGH WI AND NORTHERN IL TUE PM. PARTLY CLOUDY TO MOSTLY
CLEAR SKIES EXPECTED TUE NGT WITH SFC RIDGE AXIS BUILDING IN.
LOWS MAINLY UPPER TEENS TO LOWER 20S... BUT IF WINDS SHOULD
GO LIGHT FOR ANY LENGTH OF TIME THEN COULD SEE MINS AS COLD AS
AROUND 14-17 DEGS ESPECIALLY WEST/SOUTHWEST SECTIONS BEING IN
CLOSE PROXIMITY TO RIDGE AXIS.
WED-SAT... OVERALL MODERATING TEMPS LOOK TO BE IN STORE DURING
THE PERIOD... WITH TEMPS EDGING NEAR NORMAL TOWARD THE
END OF PERIOD AS THE PERSISTENT BLOCKING PATTERN OVER NORTH
AMERICA RESPONSIBLE FOR LOCKING IN THE COLD AIR IS SHOWN
TO BREAK DOWN. WITH THIS WARMING TREND WILL ALSO COME AT LEAST
SOME THREAT OF MAINLY LIGHT PRECIPITATION OVER THE LATTER HALF OF
THE WEEK BEING IN FAIRLY CLOSE PROXIMITY TO MID LEVEL BAROCLINIC
ZONE AND SUBJECT TO WEAK IMPULSES PROPAGATING DOWN IN NORTHWEST
FLOW ALOFT. CONSENSUS MODEL INTRODUCED SEVERAL PERIODS OF SLIGHT
CHC POPS FROM WED NGT THROUGH FRI... BUT GIVEN THE WEAK AND
VARYING SIGNAL FROM THE MODELS IT WAS COLLABORATED WITH
SURROUNDING OFFICES TO LOWER PRECIPITATION CHANCES BELOW MENTION
THROUGH FRI AND AWAIT FOR SOME BETTER CONSISTENCY. THE SIGNAL IS
STRONGER AND MORE CONSISTENT BY NEXT WEEKEND AND HAVE THEREFORE
LEFT IN PRECIPITATION CHCS BY SAT NGT. BEYOND THE SCOPE OF THE
EXTENDED... THE PATTERN REMAINS QUITE ACTIVE WITH THE MEDIUM RANGE
MODELS POINTING TO ANOTHER STORM SYSTEM POSSIBLY IMPACTING THE
AREA TOWARD THE MIDDLE PORTION OF THE FIRST WEEK OF APRIL WITH THE
POTENTIAL FOR AT LEAST MODERATE PRECIPITATION AMOUNTS WITH MAINLY
RAIN AND POSSIBLY SOME SNOW SUGGESTED. 05
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 632 AM CDT SUN MAR 24 2013
IFR/MVFR CONDITIONS WILL CONTINUE THROUGH 00Z/25 WITH LIFR
CONDITIONS MOST PROBABLE AT KBRL AS THE STORM SYSTEM MOVES INTO
THE OHIO VALLEY. AFT 00Z/25 IFR/MVFR CONDITIONS WILL SLOWLY
IMPROVE TO MVFR AS SNOW INTENSITIES GRADUALLY DECREASE. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR
IAZ087>089-098-099.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ025-
026-034-035.
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MOZ009-
010.
&&
$$
SHORT TERM...08
LONG TERM...05
AVIATION...08
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
348 AM CDT SUN MAR 24 2013
.SYNOPSIS...
ISSUED AT 322 AM CDT SUN MAR 24 2013
06Z SFC ANALYSIS HAS THE LOW IN NORTHERN MISSISSIPPI WITH AN
INVERTED TROF INTO MISSOURI. ANOTHER TROF RAN FROM EASTERN MINNESOTA
INTO EASTERN IOWA. DEW POINTS WERE IN THE TEENS AND 20S OVER THE
GREAT LAKES AND MID MISSISSIPPI VALLEY WITH 30S AND HIGHER FROM THE
OHIO VALLEY ON SOUTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 322 AM CDT SUN MAR 24 2013
OVERALL AN INTERESTING SYSTEM. THE TRENDS OF BRINGING THE SYSTEM
NORTH HAVE ENDED UP BEING INCORRECT WITH THE MAIN LOW PASSING WELL
SOUTH OF THE AREA.
SATELLITE/RADAR SHOWS A BREAK IN THE SNOW ACROSS NORTHERN MISSOURI
BUT RAP TRENDS AND RECENT WATER VAPOR TRENDS INDICATE THIS BREAK IN
THE SNOW IS FILLING. THE WAA TOOL INDICATES THE BETTER SNOW WILL BE
ACROSS THE SOUTH IN THE HEADLINE AREA. HOWEVER...TEMPERATURES AT OR
JUST BELOW FREEZING IS ALLOWING SOME MELTING TO OCCUR WITH
ACCUMULATIONS BEING ON ELEVATED SURFACES. PAVEMENT TEMPERATURES ARE
AT OR ABOVE FREEZING SO MELTING IS OCCURRING THERE AS WELL.
SO...WILL CONTINUE WITH THE CURRENT HEADLINES AS IS. THE HWY 20
CORRIDOR HAS NOT YET SEEN ANY SNOW BUT THAT SHOULD CHANGE THIS
MORNING AS THE NEXT ROUND OF FORCING MOVES INTO THE AREA. INDIRECT
SOLAR INSOLATION WILL HELP PUSH TEMPERATURES ABOVE FREEZING DURING
THE DAY SO ADDITIONAL MELTING AND COMPACTION WILL OCCUR.
THE FURTHER SOUTH PASSAGE OF THE SYSTEM AND WARM TEMPERATURES WILL
HELP SUPPRESS OVERALL SNOWFALL AMOUNTS. IN THE ADVISORY AREA THE
EXTREME SOUTH PART OF THE CWFA SHOULD SEE 3-4 INCHES BY EVENING WITH
1-2 BY THE TIME ONE REACHES THE I-80 CORRIDOR. NORTH OF HWY 30
AMOUNTS SHOULD BE APPROACHING AN INCH.
TONIGHT...LIGHT SNOW WILL CONTINUE WITH IT ENDING ACROSS THE
NORTHERN THIRD OF THE CWFA AFTER MIDNIGHT. SOUTH OF A KOTM TO KGBG
LINE AMOUNTS AROUND OR JUST OVER AN INCH ARE EXPECTED WITH NOT QUITE
AN INCH AROUND THE I-80 CORRIDOR. NORTH OF HWY 30 A DUSTING TO ONE
HALF INCH IS EXPECTED. ..08..
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 322 AM CDT SUN MAR 24 2013
LIGHT SNOW TO EXIT FAR SOUTHERN COUNTIES MON AM WITH PASSAGE
OF ELONGATED WEST-EAST UPPER TROUGH ON BACKSIDE OF OHIO VLY
SHORTWAVE. FEW FLURRIES MAY LINGER ACROSS ENTIRE AREA MON
WITH CYCLONIC FLOW AND COLD ADVECTION. 925 MB TEMPS AROUND
-5C SUPPORTS HIGHS MAINLY IN THE MIDDLE 30S. MON NGT... WITH
CONTINUED COLD ADVECTION AND CYCLONIC FLOW EXPECT PARTLY TO
MOSTLY CLOUDY SKIES AND THUS STAYED NEAR OR JUST ABOVE WARM
SIDE OF GUIDANCE ON LOWS. HOWEVER... AS CLOUDS GO SO GO THE
LOW TEMPS AND WILL NEED TO WATCH FOR POSSIBLY MORE CLEARING
AND COLDER LOWS WITH SOME SUGGESTION OF WEAK MID/UPPER LEVEL
RIDGING IN WAKE OF UPPER TROUGH.
TUE-TUE NGT... CYCLONIC FLOW TO KEEP AT LEAST PARTLY CLOUDY
SKIES TUE ESPECIALLY EASTERN 1/3-1/2... WITH ONLY SLIGHT
MODERATION ON TEMPS BY 1-3 DEGS FROM THOSE OF MON. CANT RULE
OUT FEW FLURRIES OR EVEN BRIEF SNOW SHOWER FAR EAST WITH
ENOUGH HEATING AS MODELS DEPICT WEAK ENERGY ROTATING DOWN
THROUGH WI AND NORTHERN IL TUE PM. PARTLY CLOUDY TO MOSTLY
CLEAR SKIES EXPECTED TUE NGT WITH SFC RIDGE AXIS BUILDING IN.
LOWS MAINLY UPPER TEENS TO LOWER 20S... BUT IF WINDS SHOULD
GO LIGHT FOR ANY LENGTH OF TIME THEN COULD SEE MINS AS COLD AS
AROUND 14-17 DEGS ESPECIALLY WEST/SOUTHWEST SECTIONS BEING IN
CLOSE PROXIMITY TO RIDGE AXIS.
WED-SAT... OVERALL MODERATING TEMPS LOOK TO BE IN STORE DURING
THE PERIOD... WITH TEMPS EDGING NEAR NORMAL TOWARD THE
END OF PERIOD AS THE PERSISTENT BLOCKING PATTERN OVER NORTH
AMERICA RESPONSIBLE FOR LOCKING IN THE COLD AIR IS SHOWN
TO BREAK DOWN. WITH THIS WARMING TREND WILL ALSO COME AT LEAST
SOME THREAT OF MAINLY LIGHT PRECIPITATION OVER THE LATTER HALF OF
THE WEEK BEING IN FAIRLY CLOSE PROXIMITY TO MID LEVEL BAROCLINIC
ZONE AND SUBJECT TO WEAK IMPULSES PROPAGATING DOWN IN NORTHWEST
FLOW ALOFT. CONSENSUS MODEL INTRODUCED SEVERAL PERIODS OF SLIGHT
CHC POPS FROM WED NGT THROUGH FRI... BUT GIVEN THE WEAK AND
VARYING SIGNAL FROM THE MODELS IT WAS COLLABORATED WITH
SURROUNDING OFFICES TO LOWER PRECIPITATION CHANCES BELOW MENTION
THROUGH FRI AND AWAIT FOR SOME BETTER CONSISTENCY. THE SIGNAL IS
STRONGER AND MORE CONSISTENT BY NEXT WEEKEND AND HAVE THEREFORE
LEFT IN PRECIPITATION CHCS BY SAT NGT. BEYOND THE SCOPE OF THE
EXTENDED... THE PATTERN REMAINS QUITE ACTIVE WITH THE MEDIUM RANGE
MODELS POINTING TO ANOTHER STORM SYSTEM POSSIBLY IMPACTING THE
AREA TOWARD THE MIDDLE PORTION OF THE FIRST WEEK OF APRIL WITH THE
POTENTIAL FOR AT LEAST MODERATE PRECIPITATION AMOUNTS WITH MAINLY
RAIN AND POSSIBLY SOME SNOW SUGGESTED. 05
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 322 AM CDT SUN MAR 24 2013
MVFR TO IFR CONDITIONS WILL PERSIST ACROSS EASTERN IOWA AND NORTHERN
ILLINOIS THROUGH 00Z/25. BRIEF PERIODS OF LIFR WILL ALSO BE
POSSIBLE...ESPECIALLY AT KBRL. AFT 00Z/25 CONDITIONS SHOULD SLOWLY
IMPROVE TO MVFR. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR
IAZ087>089-098-099.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ025-
026-034-035.
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MOZ009-
010.
&&
$$
SHORT TERM...08
LONG TERM...05
AVIATION...08
AREA FORECAST DISCUSSION...UPDATED
NWS DES MOINES IA
1151 PM CDT SAT MAR 23 2013
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TONIGHT/...
SYSTEM CONTINUES TO DIG SOUTHWARD THROUGH THE FRONT RANGE THIS
AFTERNOON WITH WIDESPREAD SNOWFALL ACROSS THE PLAINS. RECENTLY...
PRECIPITATION HAS BEEN EXPANDING FROM EASTERN KANSAS INTO WESTERN
MISSOURI IN WARM ADVECTION AIR OF THE SYSTEM. SOME MID TO HIGH
CLOUDINESS HAS SPREAD ACRS IOWA ALTHOUGH LOW LEVEL DRY AIR CONTINUES
TO MOVE IN FROM THE NORTHEAST. RECENT MODEL OUTPUT FROM THE 12Z GFS
PLUS THE HOURLY UPDATES FROM THE RAP CONTINUE TO INDICATE LATER
ONSET FOR MUCH OF THE FORECAST AREAS TONIGHT. THE NAM HAS BEEN MOST
AGGRESSIVE IN SPREADING SNOW INTO THE STATE THIS EVENING BUT SEEMS
TO BE THE ODD MODEL OUT AT THIS POINT WITH 18Z RUN BACKING OFF THE
MORE PROGRESSIVE 12Z RUN. HAVE GENERALLY STALLED THE ONSET OF
PRECIPITATION ACRS CENTRAL IOWA UNTIL LATER EVENING AND ACROSS THE
NORTH UNTIL WELL AFTER MIDNIGHT. NEWEST 18Z RAP WOULD NOT EVEN
BRING SNOW INTO DES MOINES UNTIL NEARLY 12Z ON SUNDAY AND REMAINS
DRY NORTH OF HIGHWAY 30.
ALL MODELS ALSO HAVE A BAND OF SNOW ACROSS NORTHWEST IOWA TONIGHT IN
A BAND OF WEAKER FORCING AHEAD OF UPPER CUTOFF CURRENTLY IN THE
DAKOTAS. ALREADY SOME LIGHT SNOW REPORTED IN SIOUX CITY AND HAVE
MAINTAINED THE POPS IN THE FAR WEST AND NORTHWEST FOR THIS AXIS OF
PRECIPITATION OVERNIGHT. ADVISORY WILL REMAIN INTACT FOR CURRENTLY
LOCATIONS ALTHOUGH HEAVIEST SNOWFALL APPEARS TO BE PRIMARILY IN THE
FAR SOUTHEAST OVERNIGHT WHERE AROUND 2 TO POSSIBLY 3 INCHES IS
EXPECTED. DES MOINES METRO MAY SEE AN INCH OR SO WITH LIGHT AMOUNTS
TOWARD THE NORTH.
.LONG TERM /SUNDAY THROUGH SATURDAY/...
MAIN FORECAST CONCERN WILL BE WITH PRECIPITATION CHANCES FOR
SUNDAY AND MONDAY. EXPECT WIDESPREAD SNOW TO BE ONGOING AT
BEGINNING OF PERIOD...ESPECIALLY ACROSS THE SOUTH AS LOW PRESSURE
SYSTEM PUSHES EAST ACROSS MISSOURI. SOUNDINGS AND CROSS SECTIONS
INDICATE GOOD SATURATION AND FORCING...ESPECIALLY ACROSS THE
SOUTH. FORCING BECOMES MUCH WEAKER FURTHER NORTH AWAY FROM THE
LOW...BUT ENOUGH TO RESULT IN AT LEAST LIGHT SNOWFALL THROUGHOUT
THE DAY MONDAY. BEST FORCING WILL BE EARLY...BEFORE 18Z AND EXPECT
TO SEE BEST SNOWFALL RATES THEN. BEST FORCING IS ABOVE THE
DENDRITIC LAYER...AND DO NOT ANTICIPATE SNOWFALL RATIOS TO BE MUCH
HIGHER THAN 10/1. DRY AIR WILL BEGIN TO PUSH BACK IN BEHIND SYSTEM
OVERNIGHT MONDAY...WITH PRECIPITATION ENDING ACROSS THE NE.
HOWEVER...GOOD VORT MAX PUSHING AROUND LOW WILL KEEP LINGERING
SNOW CHANCES ACROSS THE SW...BUT AGAIN WITH WEAKER FORCING ONLY
LIGHT SNOW EXPECTED. LINGERING LOW LEVEL SATURATION WILL ALLOW FOR
LINGERING LIGHT SNOW AND FLURRIES THROUGH MONDAY WITH COLD SURFACE
TEMPERATURES. SYSTEM WILL CONTINUE TO PULL EAST...AND MAY SEE
ADDITIONAL LINGERING FLURRIES THROUGH TUESDAY. TOTAL ACCUMULATIONS
ARE SIMILAR TO GOING WITH HIGHER TOTALS ACROSS THE SOUTH. WINDS WILL
BE STRONG BEHIND LOW...BUT WILL GENERALLY STAY BELOW 30MPH AND
WILL LEAD TO SOME IMPACTS...MOSTLY WITH ROADS AND REDUCED
VISIBILITIES....BUT DO NOT ANTICIPATE SIGNIFICANT IMPACTS WITH
SNOWFALL. GIVEN DURATION OF SNOWFALL...ADVISORY SEEMS WARRANTED
AND WILL LEAVE AS IS. HOWEVER...MAY NEED TO BE EXTENDED IN TIME
ACROSS THE SOUTH FOR LINGER SNOWFALL INTO MONDAY NIGHT...BUT WILL
LEAVE FOR FUTURE UPDATES AS MODELS CONTINUE TO VARY ON PLACEMENT
OF LOW.
TEMPERATURES WILL BEGIN TO WARM BY MID WEEK WITH SOUTHERLY SURFACE
FLOW AND INCREASING WAA. MODELS BRING ANOTHER LOW PRESSURE SYSTEM
ACROSS CANADA...WITH TRAILING FRONTAL BOUNDARY ACROSS MIDWEST.
THIS WILL BE FOCUS FOR PRECIPITATION CHANCES THROUGH THE WEEKEND.
HOWEVER...WITH WARMER TEMPERATURES PRECIPITATION LIKELY RAIN.
STILL SOME UNCERTAINTY IN TIMING AND LOCATION OF RAIN...AND HAVE
LEFT SLIGHT CHANCES FOR NOW.
&&
.AVIATION...24/06Z
SNOW HAS BEEN SLOW TO SPREAD NORTHWARD...BUT CONTINUES TO AFFECT
KDSM/KOTM AT THIS TIME. UPSTREAM RADAR AND SFC OBS INDICATE A 2 TO 3
HR GAP IN THE SNOW APPROACHING FROM THE SW...AND HAVE ATTEMPTED TO
TIME THIS GAP AT KDSM/KOTM WITH SNOW SPREADING INTO THE REMAINING
TERMINALS WITH THE SECOND BATCH MORE TOWARD 12Z. HOWEVER...THE
TIMING OF ONSET AT ALL TERMINALS REMAINS SOMEWHAT UNCERTAIN AND
AMENDMENTS WILL PROBABLY BE NECESSARY. IN THE MORE MODERATE
SNOWFALL...MAINLY AT KDSM/KOTM...IFR AND LOWER CONDITIONS WILL BE
MORE LIKELY WITH MVFR MORE LIKELY FURTHER NORTH. CONDITIONS WILL NOT
IMPROVE SUBSTANTIALLY ON SUNDAY...AND WILL PROBABLY DETERIORATE
AGAIN WITH BR DEVELOPMENT AFTER DARK ON SUNDAY NIGHT.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 PM CDT
SUNDAY FOR ADAIR-ADAMS-APPANOOSE-CASS-CLARKE-DAVIS-DECATUR-LUCAS-
MADISON-MAHASKA-MARION-MONROE-RINGGOLD-TAYLOR-UNION-WAPELLO-
WARREN-WAYNE.
&&
$$
SHORT TERM...COGIL
LONG TERM...AWB
AVIATION...LEE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
952 PM EDT MON MAR 25 2013
.UPDATE...
ISSUED AT 952 PM EDT MON MAR 25 2013
BASED ON LOCAL 00Z RAOBS...WHICH SHOW INVERTED V T/TD PROFILES
THRU ABOUT H85 CONSISTENT WITH INCRSG SOLAR ANGLE/DAYTIME HEATING...
LOWERED POPS/REMOVED FZDZ THRU ABOUT 06Z. STILL LOOKING FOR
COMBINATION OF ARRIVAL OF DEEPER MSTR/SHRTWV FM THE NE ALONG WITH
SOME ACCOMPANYING DEEP LYR QVECTOR CNVGC IN THE PRESENCE OF
NOCTURNAL COOLING AND PERSISTENT CYC LLVL NNE FLOW TO GENERATE SOME
-SHSN OVERNGT IN SPITE OF MARGINAL H85 TEMPS FOR LES. SINCE FCST
PROFILES FM MOST GUIDANCE STILL SHOW BULK OF UVV FOCUSED IN THE
LLVLS/UPSLOPE FORCING AND BLO THE DGZ...RETAINED MENTION OF FZDZ.
BUT DID CUT BACK TO PATCHY BASED ON SOMEWHAT HIER SFC DEWPT
DEPRESSIONS/DRIER LLVL AIR.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 356 PM EDT MON MAR 25 2013
...CHALLENGING FORECAST IN STORE THIS AFTERNOON THROUGH TUESDAY...
BROAD CYCLONIC FLOW IS PROGGED TO LINGER OVER MUCH OF THE GREAT
LAKES REGION THIS AFTERNOON THROUGH MUCH OF THE DAY TUESDAY AS A LOW
PRESSURE SYSTEM SLOWLY SHIFTS FROM THE OHIO VALLEY THIS
NORTHEASTWARD TOWARD THE NEW ENGLAND AREA. RADAR IS SHOWING SEVERAL
RETURNS NEAR LAKE SUPERIOR. SURFACE OBSERVATIONS AND WEBCAMS
INDICATE THAT THIS PRECIPITATION IS A MIX OF LIGHT FREEZING RAIN AS
WELL AS LIGHT SNOW SHOWERS. THE MAIN ISSUE FOR THE DAY INTO THE
NIGHT WILL BE PRECIPITATION TYPE AS SOUNDINGS SHOW ONLY MARGINAL
SUPPORT FOR SNOW DEVELOPMENT WITH THE TOP OF THE MOIST LAYER
REACHING AROUND -10C THROUGH MID MORNING. RUC AND NAM SOUNDING
INDICATE SLIGHTLY COOLER AIR...AROUND 12C...MOVING IN NEAR THE TOP
OF THE MOIST LAYER DURING THE AFTERNOON HOURS. THIS MAY TRANSITION
THE FZDZ OVER TO MORE OF A LIGHT SNOW AND FZDZ MIX OR TRANSITION
OVER TO ALL SNOW. AROUND 00Z SOUNDINGS WARM SLIGHTLY ALOFT AHEAD OF
THE NEXT 500MB TROUGH ROTATING INTO THE AREA. THIS WILL ALLOW THE
PRECIPITATION TO TRANSITION BACK TO A -FZDZ/-SHSN MIX...WHICH WILL
LAST THROUGH MID AFTERNOON BEFORE SLOWLY TAPERING OFF. CONFIDENCE
LEVEL IN ANY ONE TYPE OF PRECIPITATION IS LOW AS TEMPS ALOFT ARE
HUGGING THE -12C ISOTHERM WHICH IS WHERE ICE IS INTRODUCED INTO THE
CLOUD...THEREFORE HAVE KEPT A MIX OF FZDZ AND -SHSN IN THE FORECAST.
DELTA T VALUES ARE EXPECTED TO BE AROUND -12 TO -14 ALONG WITH MOIST
LOW LEVEL PROFILES WHICH WILL CONTINUE TO SUPPORT LAKE EFFECT
PRECIPITATION...WHICH MAY BE ENHANCED FURTHER OVERNIGHT AS THE
TROUGH PASSES DIRECTLY OVERHEAD. THERE IS ALSO AN UPSLOPE COMPONENT
WHICH MAY HELP FOCUS THE PRECIPITATION OVER THE HIGHER
TERRAIN...ESPECIALLY IN NORTH CENTRAL LOCATIONS AS WELL AS OVER THE
KEWEENAW.
TUESDAY...LAKE EFFECT SHSN AND FZDZ WILL LIKELY LINGER THROUGH THE
MID TO LATE MORNING HOURS BEFORE THE 500MB TROUGH SHIFTS TO THE
SOUTH OF THE UPPER PENINSULA. THIS WILL ALLOW SURFACE TO 850 DELTA T
VALUES TO BE AROUND -8C TO -9C...EFFECTIVELY REDUCING THE LAKE
EFFECT PRECIPITATION. SCATTERED FZDZ MAY LINGER OVER THE HIGH
TERRAIN IN CENTRAL UPPER MI AS A SIGNIFICANT AMOUNT OF LOW LEVEL
MOISTURE REMAINS IN PLACE AND UPSLOPE NORTH TO NORTH-NORTHWEST FLOW
CONTINUES TO MOVE FROM LAKE SUPERIOR INLAND.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 356 PM EDT MON MAR 25 2013
UPPER TROUGH THAT HAS BEEN INFLUENCING THE AREA OVER THE LAST
SEVERAL DAYS WILL BEGIN TO SHIFT EAST TUESDAY NIGHT INTO
WEDNESDAY...ALLOWING A WEAK UPPER RIDGE AND SURFACE HIGH PRESSURE TO
MOVE IN WEDNESDAY NIGHT AND REMAIN THROUGH FRIDAY.
LINGERING MOISTURE UNDER THE CYCLONIC FLOW FROM THE UPPER AND
SURFACE LOW OF THE NEW ENGLAND STATES WILL CONTINUE TO BRING THE
POTENTIAL FOR CLOUDS AND PRECIPITATION FOR TUESDAY NIGHT AND
WEDNESDAY. THIS WILL BE ESPECIALLY TRUE FOR LOCATIONS FAVORED BY
NORTH TO NORTHWEST WINDS. MODELS ARE FAIRLY PERSISTENT ON THE LOWER
LEVEL MOISTURE...925-850MB...BEING PRESENT FOR TUESDAY NIGHT INTO
WEDNESDAY MORNING WHILE A SURFACE TROUGH DROPS SOUTH ACROSS EASTERN
LAKE SUPERIOR. BEST CHANCES FOR PRECIPITATION LOOK TO BE ON TUESDAY
NIGHT INTO WEDNESDAY MORNING...BEFORE THE DEEPER MOISTURE DEPARTS
AND SUBSIDENCE FROM THE APPROACHING HIGH BEGINS TO INFLUENCE THE
CLOUD THICKNESS. WILL CONTINUE TO MENTION SLIGHT CHANCE AND A FEW
LOCALIZED CHANCE POPS FOR THE FAVORED NORTH-NORTHWEST LOCATIONS.
TYPE LOOKS TO BE A CONCERN AGAIN ON TUESDAY NIGHT INTO
WEDNESDAY...WITH CLOUD TOP TEMPERATURES BARELY RISING ABOVE -10C. AS
HAS BEEN THE CASE OVER THE LAST COUPLE OF DAYS...THE LIGHTER SHOWERS
WILL LIKELY BE FZDZ AND IF ANY STRONGER SHOWERS OCCUR THERE COULD BE
SNOW ASSOCIATED WITH IT. WILL LIMIT THE SNOW MENTION THOUGH...AS
CLOUD TOPS APPEAR TO BE A COUPLE DEGREES WARMER THAN THE LAST COUPLE
OF DAYS.
WEDNESDAY NIGHT INTO THURSDAY WILL BE THE TRANSITION PERIOD...AS THE
HIGH PRESSURE RIDGE MOVES OVER THE AREA FROM THE UPPER MISSISSIPPI
VALLEY AND THE RESIDUAL MOISTURE BECOMES FORCED BELOW 925MB. THIS
DOES LEAD TO SOME CONCERN FOR LOW CLOUDS BECOMING TRAPPED OVER THE
AREA ON WEDNESDAY NIGHT. SFC TO 925MB DELTA-T VALUES ARE ONLY AROUND
8-9C...SO LAKE INFLUENCE WILL BE BE LIMITED. BUT IF CLOUDS ARE STILL
PRESENT FROM WEDNESDAY...THE INCREASING SUBSIDENCE INVERSION AND
LACK OF MIXING DURING THE OVERNIGHT HOURS WILL TRY TO KEEP THEM IN
PLACE. THUS...WILL TRY TO HOLD ONTO MORE OF A PARTLY/MOSTLY CLOUDY
SKY FOR WEDNESDAY NIGHT AND THEN HAVE DAYTIME MIXING TRY TO REDUCE
CLOUDS SOMEWHAT ON THURSDAY. ONE THING TO WATCH ON THURSDAY WILL BE
THE INCREASING SFC-925MB LAPSE RATES IF BREAKS DO OCCUR. THIS COULD
LEAD TO DIURNAL CU REDEVELOPING OVER INTERIOR WEST LOCATIONS WHERE
LAPSE RATES APPROACH 9C/KM. WITH PLENTY OF DRY AIR...THURSDAY NIGHT
INTO FRIDAY SHOULD BE DRY AND PARTLY/MOSTLY CLEAR EVEN THOUGH A
SHORTWAVE MOVES ACROSS THE AREA IN THE NORTHWEST FLOW.
EXPECT GRADUAL WARMING TEMPERATURES THROUGH THE WEEK...ESPECIALLY
FOR THURSDAY AND FRIDAY WITH THE LATE MARCH SUNSHINE. WEDNESDAY
SHOULD SEE HIGHS IN THE MID-UPPER 30S AND THEN UPPER 30S THROUGH MID
40S FOR THURSDAY AND FRIDAY. 00Z ECMWF AND MOST OF IT/S ENSEMBLE
MEMBERS HAVE KSAW REACHING THE LOW 40S ON FRIDAY AND SATURDAY.
THUS...IT IS LOOKING LIKE OUR OFFICE WILL END UP REACHING 40 DEGREES
AND KEEP THIS MARCH FROM BEING THE FIRST MARCH ON RECORD WHERE WE
DIDN/T REACH 40 DEGREES.
CHANGES LOOK TO ARRIVE FOR THIS WEEKEND...AS A STRONG SHORTWAVE
DIVES SOUTHEAST THROUGH CENTRAL CANADA AND INTO THE UPPER GREAT
LAKES FOR LATE SATURDAY INTO SUNDAY. MODELS ARE FAIRLY CONSISTENT
ON THIS IDEA...WHICH INCREASES CONFIDENCE INTO THE FIRST PART OF
NEXT WEEK. AT THIS TIME...LOOKS LIKE ASSOCIATED COLD FRONT WILL
MOVE THROUGH ON SATURDAY AFTERNOON/NIGHT. BASED OFF THICKNESS AND
THERMAL PROFILES...LOOKS LIKE A MIX OF RAIN/SNOW AS THE FRONT MOVES
THROUGH. WITH THE DRY HIGH IN PLACE...QPF AMOUNTS LOOK TO BE
LIMITED AT THIS POINT WITH THE INITIAL FRONT. THEN BEHIND THE FRONT
ON SUNDAY...MAIN SHORTWAVE MOVES THROUGH AND COLDER 850MB TEMPS
SURGE SOUTHEAST AND REACH -12C/ECMWF OR -10C/GFS BY MONDAY MORNING.
WITH THE NORTHWEST FLOW GENERATED BY THE HIGH OVER THE NORTHERN
PLAINS...WOULD SOME LAKE EFFECT SNOW SHOWERS IN THE NORTHWEST
WIND FAVORED LOCATIONS FOR MONDAY. WILL TREND POPS UP SLIGHTLY FROM
A GENERAL MODEL CONSENSUS FOR THAT TIME FRAME NEAR LAKE SUPERIOR.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 722 PM EDT MON MAR 25 2013
ALTHOUGH CMX MAY SEE SOME IMPROVEMENT TO MVFR CONDITIONS EARLY IN
THE FCST PERIOD WITH A WEAKER UPSLOPE WIND COMPONENT...UPSLOPE CYC
NNE FLOW AND THE ARRIVAL OF A DISTURBANCE/SOMEWHAT DEEPER MSTR BY
LATE THIS EVNG SHOULD RESULT IN PREDOMINANT MVFR CONDITIONS THRU TUE
MRNG. IF THERE IS SOME HEAVIER SHSN/FZDZ...CONDITIONS MIGHT EVEN
DROP TO IFR AT TIMES...ESPECIALLY AT IWD/SAW WHERE THE NNE FLOW
PRESENTS A SHARPER UPSLOPE WIND COMPONENT. PASSAGE OF DISTURBANCE
AND DIURNAL HEATING ON TUE AFTN SHOULD ALLOW SOME IMPROVEMENT TO HI
END MVFR/LO END VFR CONDITIONS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 356 PM EDT MON MAR 25 2013
HIGH PRESSURE IN PLACE OVER THE NORTHERN PLAINS AND LOW PRESSURE
SHIFTING EASTWARD FROM THE OHIO VALLEY TO EASTER SEABOARD WILL LEAD
TO A TIGHT PRESSURE GRADIENT OVER LAKE SUPERIOR THROUGH TUESDAY.
THIS WILL RESULT IN NORTHERLY TO NORTHWESTERLY WINDS 15 TO 25 KNOTS.
BEYOND TUESDAY AFTERNOON...HIGH PRESSURE WILL BUILD INTO THE UPPER
GREAT LAKES REGION KEEPING WINDS GENERALLY BELOW 20 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KC
SHORT TERM...KEC
LONG TERM...SRF
AVIATION...KC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
723 PM EDT MON MAR 25 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 356 PM EDT MON MAR 25 2013
...CHALLENGING FORECAST IN STORE THIS AFTERNOON THROUGH TUESDAY...
BROAD CYCLONIC FLOW IS PROGGED TO LINGER OVER MUCH OF THE GREAT
LAKES REGION THIS AFTERNOON THROUGH MUCH OF THE DAY TUESDAY AS A LOW
PRESSURE SYSTEM SLOWLY SHIFTS FROM THE OHIO VALLEY THIS
NORTHEASTWARD TOWARD THE NEW ENGLAND AREA. RADAR IS SHOWING SEVERAL
RETURNS NEAR LAKE SUPERIOR. SURFACE OBSERVATIONS AND WEBCAMS
INDICATE THAT THIS PRECIPITATION IS A MIX OF LIGHT FREEZING RAIN AS
WELL AS LIGHT SNOW SHOWERS. THE MAIN ISSUE FOR THE DAY INTO THE
NIGHT WILL BE PRECIPITATION TYPE AS SOUNDINGS SHOW ONLY MARGINAL
SUPPORT FOR SNOW DEVELOPMENT WITH THE TOP OF THE MOIST LAYER
REACHING AROUND -10C THROUGH MID MORNING. RUC AND NAM SOUNDING
INDICATE SLIGHTLY COOLER AIR...AROUND 12C...MOVING IN NEAR THE TOP
OF THE MOIST LAYER DURING THE AFTERNOON HOURS. THIS MAY TRANSITION
THE FZDZ OVER TO MORE OF A LIGHT SNOW AND FZDZ MIX OR TRANSITION
OVER TO ALL SNOW. AROUND 00Z SOUNDINGS WARM SLIGHTLY ALOFT AHEAD OF
THE NEXT 500MB TROUGH ROTATING INTO THE AREA. THIS WILL ALLOW THE
PRECIPITATION TO TRANSITION BACK TO A -FZDZ/-SHSN MIX...WHICH WILL
LAST THROUGH MID AFTERNOON BEFORE SLOWLY TAPERING OFF. CONFIDENCE
LEVEL IN ANY ONE TYPE OF PRECIPITATION IS LOW AS TEMPS ALOFT ARE
HUGGING THE -12C ISOTHERM WHICH IS WHERE ICE IS INTRODUCED INTO THE
CLOUD...THEREFORE HAVE KEPT A MIX OF FZDZ AND -SHSN IN THE FORECAST.
DELTA T VALUES ARE EXPECTED TO BE AROUND -12 TO -14 ALONG WITH MOIST
LOW LEVEL PROFILES WHICH WILL CONTINUE TO SUPPORT LAKE EFFECT
PRECIPITATION...WHICH MAY BE ENHANCED FURTHER OVERNIGHT AS THE
TROUGH PASSES DIRECTLY OVERHEAD. THERE IS ALSO AN UPSLOPE COMPONENT
WHICH MAY HELP FOCUS THE PRECIPITATION OVER THE HIGHER
TERRAIN...ESPECIALLY IN NORTH CENTRAL LOCATIONS AS WELL AS OVER THE
KEWEENAW.
TUESDAY...LAKE EFFECT SHSN AND FZDZ WILL LIKELY LINGER THROUGH THE
MID TO LATE MORNING HOURS BEFORE THE 500MB TROUGH SHIFTS TO THE
SOUTH OF THE UPPER PENINSULA. THIS WILL ALLOW SURFACE TO 850 DELTA T
VALUES TO BE AROUND -8C TO -9C...EFFECTIVELY REDUCING THE LAKE
EFFECT PRECIPITATION. SCATTERED FZDZ MAY LINGER OVER THE HIGH
TERRAIN IN CENTRAL UPPER MI AS A SIGNIFICANT AMOUNT OF LOW LEVEL
MOISTURE REMAINS IN PLACE AND UPSLOPE NORTH TO NORTH-NORTHWEST FLOW
CONTINUES TO MOVE FROM LAKE SUPERIOR INLAND.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 356 PM EDT MON MAR 25 2013
UPPER TROUGH THAT HAS BEEN INFLUENCING THE AREA OVER THE LAST
SEVERAL DAYS WILL BEGIN TO SHIFT EAST TUESDAY NIGHT INTO
WEDNESDAY...ALLOWING A WEAK UPPER RIDGE AND SURFACE HIGH PRESSURE TO
MOVE IN WEDNESDAY NIGHT AND REMAIN THROUGH FRIDAY.
LINGERING MOISTURE UNDER THE CYCLONIC FLOW FROM THE UPPER AND
SURFACE LOW OF THE NEW ENGLAND STATES WILL CONTINUE TO BRING THE
POTENTIAL FOR CLOUDS AND PRECIPITATION FOR TUESDAY NIGHT AND
WEDNESDAY. THIS WILL BE ESPECIALLY TRUE FOR LOCATIONS FAVORED BY
NORTH TO NORTHWEST WINDS. MODELS ARE FAIRLY PERSISTENT ON THE LOWER
LEVEL MOISTURE...925-850MB...BEING PRESENT FOR TUESDAY NIGHT INTO
WEDNESDAY MORNING WHILE A SURFACE TROUGH DROPS SOUTH ACROSS EASTERN
LAKE SUPERIOR. BEST CHANCES FOR PRECIPITATION LOOK TO BE ON TUESDAY
NIGHT INTO WEDNESDAY MORNING...BEFORE THE DEEPER MOISTURE DEPARTS
AND SUBSIDENCE FROM THE APPROACHING HIGH BEGINS TO INFLUENCE THE
CLOUD THICKNESS. WILL CONTINUE TO MENTION SLIGHT CHANCE AND A FEW
LOCALIZED CHANCE POPS FOR THE FAVORED NORTH-NORTHWEST LOCATIONS.
TYPE LOOKS TO BE A CONCERN AGAIN ON TUESDAY NIGHT INTO
WEDNESDAY...WITH CLOUD TOP TEMPERATURES BARELY RISING ABOVE -10C. AS
HAS BEEN THE CASE OVER THE LAST COUPLE OF DAYS...THE LIGHTER SHOWERS
WILL LIKELY BE FZDZ AND IF ANY STRONGER SHOWERS OCCUR THERE COULD BE
SNOW ASSOCIATED WITH IT. WILL LIMIT THE SNOW MENTION THOUGH...AS
CLOUD TOPS APPEAR TO BE A COUPLE DEGREES WARMER THAN THE LAST COUPLE
OF DAYS.
WEDNESDAY NIGHT INTO THURSDAY WILL BE THE TRANSITION PERIOD...AS THE
HIGH PRESSURE RIDGE MOVES OVER THE AREA FROM THE UPPER MISSISSIPPI
VALLEY AND THE RESIDUAL MOISTURE BECOMES FORCED BELOW 925MB. THIS
DOES LEAD TO SOME CONCERN FOR LOW CLOUDS BECOMING TRAPPED OVER THE
AREA ON WEDNESDAY NIGHT. SFC TO 925MB DELTA-T VALUES ARE ONLY AROUND
8-9C...SO LAKE INFLUENCE WILL BE BE LIMITED. BUT IF CLOUDS ARE STILL
PRESENT FROM WEDNESDAY...THE INCREASING SUBSIDENCE INVERSION AND
LACK OF MIXING DURING THE OVERNIGHT HOURS WILL TRY TO KEEP THEM IN
PLACE. THUS...WILL TRY TO HOLD ONTO MORE OF A PARTLY/MOSTLY CLOUDY
SKY FOR WEDNESDAY NIGHT AND THEN HAVE DAYTIME MIXING TRY TO REDUCE
CLOUDS SOMEWHAT ON THURSDAY. ONE THING TO WATCH ON THURSDAY WILL BE
THE INCREASING SFC-925MB LAPSE RATES IF BREAKS DO OCCUR. THIS COULD
LEAD TO DIURNAL CU REDEVELOPING OVER INTERIOR WEST LOCATIONS WHERE
LAPSE RATES APPROACH 9C/KM. WITH PLENTY OF DRY AIR...THURSDAY NIGHT
INTO FRIDAY SHOULD BE DRY AND PARTLY/MOSTLY CLEAR EVEN THOUGH A
SHORTWAVE MOVES ACROSS THE AREA IN THE NORTHWEST FLOW.
EXPECT GRADUAL WARMING TEMPERATURES THROUGH THE WEEK...ESPECIALLY
FOR THURSDAY AND FRIDAY WITH THE LATE MARCH SUNSHINE. WEDNESDAY
SHOULD SEE HIGHS IN THE MID-UPPER 30S AND THEN UPPER 30S THROUGH MID
40S FOR THURSDAY AND FRIDAY. 00Z ECMWF AND MOST OF IT/S ENSEMBLE
MEMBERS HAVE KSAW REACHING THE LOW 40S ON FRIDAY AND SATURDAY.
THUS...IT IS LOOKING LIKE OUR OFFICE WILL END UP REACHING 40 DEGREES
AND KEEP THIS MARCH FROM BEING THE FIRST MARCH ON RECORD WHERE WE
DIDN/T REACH 40 DEGREES.
CHANGES LOOK TO ARRIVE FOR THIS WEEKEND...AS A STRONG SHORTWAVE
DIVES SOUTHEAST THROUGH CENTRAL CANADA AND INTO THE UPPER GREAT
LAKES FOR LATE SATURDAY INTO SUNDAY. MODELS ARE FAIRLY CONSISTENT
ON THIS IDEA...WHICH INCREASES CONFIDENCE INTO THE FIRST PART OF
NEXT WEEK. AT THIS TIME...LOOKS LIKE ASSOCIATED COLD FRONT WILL
MOVE THROUGH ON SATURDAY AFTERNOON/NIGHT. BASED OFF THICKNESS AND
THERMAL PROFILES...LOOKS LIKE A MIX OF RAIN/SNOW AS THE FRONT MOVES
THROUGH. WITH THE DRY HIGH IN PLACE...QPF AMOUNTS LOOK TO BE
LIMITED AT THIS POINT WITH THE INITIAL FRONT. THEN BEHIND THE FRONT
ON SUNDAY...MAIN SHORTWAVE MOVES THROUGH AND COLDER 850MB TEMPS
SURGE SOUTHEAST AND REACH -12C/ECMWF OR -10C/GFS BY MONDAY MORNING.
WITH THE NORTHWEST FLOW GENERATED BY THE HIGH OVER THE NORTHERN
PLAINS...WOULD SOME LAKE EFFECT SNOW SHOWERS IN THE NORTHWEST
WIND FAVORED LOCATIONS FOR MONDAY. WILL TREND POPS UP SLIGHTLY FROM
A GENERAL MODEL CONSENSUS FOR THAT TIME FRAME NEAR LAKE SUPERIOR.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 722 PM EDT MON MAR 25 2013
ALTHOUGH CMX MAY SEE SOME IMPROVEMENT TO MVFR CONDITIONS EARLY IN
THE FCST PERIOD WITH A WEAKER UPSLOPE WIND COMPONENT...UPSLOPE CYC
NNE FLOW AND THE ARRIVAL OF A DISTURBANCE/SOMEWHAT DEEPER MSTR BY
LATE THIS EVNG SHOULD RESULT IN PREDOMINANT MVFR CONDITIONS THRU TUE
MRNG. IF THERE IS SOME HEAVIER SHSN/FZDZ...CONDITIONS MIGHT EVEN
DROP TO IFR AT TIMES...ESPECIALLY AT IWD/SAW WHERE THE NNE FLOW
PRESENTS A SHARPER UPSLOPE WIND COMPONENT. PASSAGE OF DISTURBANCE
AND DIURNAL HEATING ON TUE AFTN SHOULD ALLOW SOME IMPROVEMENT TO HI
END MVFR/LO END VFR CONDITIONS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 356 PM EDT MON MAR 25 2013
HIGH PRESSURE IN PLACE OVER THE NORTHERN PLAINS AND LOW PRESSURE
SHIFTING EASTWARD FROM THE OHIO VALLEY TO EASTER SEABOARD WILL LEAD
TO A TIGHT PRESSURE GRADIENT OVER LAKE SUPERIOR THROUGH TUESDAY.
THIS WILL RESULT IN NORTHERLY TO NORTHWESTERLY WINDS 15 TO 25 KNOTS.
BEYOND TUESDAY AFTERNOON...HIGH PRESSURE WILL BUILD INTO THE UPPER
GREAT LAKES REGION KEEPING WINDS GENERALLY BELOW 20 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KEC
LONG TERM...SRF
AVIATION...KC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
149 PM EDT SUN MAR 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 502 AM EDT SUN MAR 24 2013
WV IMAGERY AND RUC ANALYSIS INDICATED PERSISTENT HIGH LATITUDE
MID/UPPER LEVEL RIDGING FROM SCANDINAVIA INTO NORTHERN CANADA
RESULTING IN LOWER HEIGHTS AND COLDER AIR TO THE SOUTH ACROSS SRN
CANADA AND THE NRN CONUS. A WEAK RIDGE EXTENDED ACROSS THE WRN
GREAT LAKES BTWN MID LEVEL LOWS OVER THE DAKOTAS AND CANADIAN
MARATIMES. AT THE SFC...WEAK NE FLOW PREVAILED BETWEEN HIGH PRES
OVER SASK INTO NRN MANITOBA AND LOW PRES OVER THE LOWER MS VALLEY.
IR SATELLITE LOOP SHOWED AN EXTENSIVE AREA OF CLOUDS ACROSS THE
REGION WITH A RELATIVELY SMALL CLEAR AREA NE OF LAKE SUPERIOR.
WITH GENERALLY WEAK ONSHORE WINDS INTO NRN UPPER MI
OVERNIGHT...RADAR INDICATED NO PCPN. HOWEVER...AS WINDS INCREASE OUT
OF THE NORTHEAST AND 850 MB TEMPS REMAIN NER -11C...EXPECT SOME
LIGHT SNOW MAY STILL DEVELOP OVER THE WEST AND N CNTRL LOCATIONS
WHERE UPSLOPE FLOW PREVAILS. SINCE TEMPS IN THE MOIST LAYER REMAINED
BORDERLINE TO SUPPORT ICE CRYSTALS...A MIX OF -SN/FLURRIES/-FZDZ MAY
BE POSSIBLE. MODELS SUGGEST THAT THE DRY AIR TO THE NORTHEAST WILL
SPREAD ACROSS LAKE SUPERIOR INTO UPPER MI THIS AFTERNOON. THIS
SHOULD BRING AN END TO ANY PCPN THAT DEVELOPS EARLY TODAY. SOME
CLEARING MAY ALSO SPREAD FROM EAST INTO CNTRL UPPER MI BY LATE THIS
AFTERNOON WHICH SHOULD HELP BOOST TEMPS INTO THE LOWER TO MID 30S.
THE MODELS WERE CONSISTENT IN BRINGING ANOTHER BATCH OF 925-700 MB
MOISTURE INTO THE AREA FROM THE NORTHEAST TONIGHT. THIS WILL BRING
INCREASING CHANCES FOR LIGHT LAKE EFFECT SNOW...ESPECIALLY AFT
06Z...TO AREAS FAVORED BY UPSLOPE NNE FLOW IN N CNTRL AND WRN UPPER
MI. SINCE DEEPER MOISTURE TO AROUND -12C IS LIKELY...-FZDZ CHANCES
WILL BE REDUCED. THE CLOUDS WILL ALSO KEEP TEMPS FROM FALLING OFF
TOO MUCH WITH MIN READINGS AGAIN ABOVE NORMAL....IN THE LOW TO MID
20S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 443 AM EDT SUN MAR 24 2013
OUR STEADY NORTHERLY FLOW OFF LAKE SUPERIOR WILL CONTINUE THROUGH
WEDNESDAY...WITH LIGHT PRECIPITATION POSSIBLE NEARLY EVERY DAY NEAR
LAKE SUPERIOR. LOOK FOR TEMPERATURES TO SLOWLY INCREASE EACH
DAY...WITH SOUTH CENTRAL AREAS NEARING 40 DEGREES FOR A HIGH ON
THURSDAY...AND REMAINING IN THE UPPER 30S AND LOW 40S TO WRAP UP THE
WORK WEEK AND START THE UPCOMING WEEKEND.
THE NEXT GOOD SURGE OF PRECIPITATION WILL BE MONDAY THROUGH TUESDAY
MORNING...AS THE MID ATLANTIC LOW ROTATES MOISTURE BACK TOWARD THE
UPPER GREAT LAKES REGION. STILL IT WILL BE SET UP AOB ABOUT
800MB...WITH THE DGZ HOVERING AT THE TOP OF THIS MOISTURE LAYER TO
AROUND 600MB. WHILE THE MOST PRISTINE SNOW CRYSTALS WILL NOT BE
EXPECTED...850MB TEMPS HOVERING BETWEEN -10 AND -12C. SNOW AMOUNTS
AROUND A HALF INCH EVERY 6 HOURS WILL BE POSSIBLE MONDAY THROUGH
TUESDAY MORNING...HIGHEST OVER THE ELEVATED TERRAIN OF MARQUETTE
COUNTY...AND ACROSS WESTERN GOGEBIC AND ONTONAGON COUNTIES.
THE 500MB TROUGH WILL LIKELY REMAIN ENTRENCHED ACROSS CENTRAL AND
EASTERN UPPER MICHIGAN THROUGH TUESDAY NIGHT INTO WEDNESDAY. AT THAT
POINT NW FLOW LOOKS TO TAKE OVER ALOFT...WITH A SERIES OF WEAKER
WAVES SLIDING NEAR THE UPPER GREAT LAKES. WHILE WE DO HAVE SLIGHT
CHANCE POPS MENTIONED FOR DAY 5/FRIDAY INTO DAY 6/SATURDAY...THE
CONFIDENCE IS VERY LOW. THE ECMWF KEEP LOW PRESSURE STUCK UP NEAR
JAMES BAY AND HUDSON BAY ON FRIDAY...WITH HIGH PRESSURE STRETCHING
FROM SOUTH CENTRAL CANADA THROUGH THE UPPER GREAT LAKES. A WEAK COLD
FRONT MAY CROSS THURSDAY NIGHT INTO FRIDAY. THE 00Z MODEL RUNS LOOK
LESS THAN IMPRESSIVE WITH THE CHANCE FOR MEASURABLE PRECIP THROUGH
THE END OF THE FORECAST PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 146 PM EDT SUN MAR 24 2013
UPSLOPE PRECIPITATION...A MIX OF -FZDZ AND -SHSN ASSOCIATED WITH
LINGERING LOW-MID LEVEL MOISTURE WILL CONTINUE THROUGH AROUND 21Z AT
KIWD AND KSAW. POCKET OF DRY AIR SEEN DIVING SOUTHWESTWARD ACROSS
LAKE SUPERIOR WILL DIMINISH THE MORE EXTENSIVE CLOUD COVER AND
PRECIP FOR A BRIEF PERIOD AT ALL THREE SITES...HOWEVER
SCATTERED-BROKEN MVFR-VFR DECK IS EXPECTED TO REMAIN IN PLACE FOR
THE MOST PART AS LAKE EFFECT CLOUDS DEVELOP IN ITS WAKE.
ADDITIONALLY...HIGH-MID LEVEL CLOUDS FROM THE PASSING SYSTEM TO THE
SOUTH ARE EXPANDING OVER UPPER MICHIGAN. OVERNIGHT PRECIPITATION
WILL START UP AGAIN...MAINLY IN THE FORM OF SNOW...AT ALL THREE
SITES. THIS WILL LAST THROUGH THE AFTERNOON HOURS ON MONDAY.
CONDITIONS ARE NOT EXPECTED TO DROP BELOW MVFR.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 502 AM EDT SUN MAR 24 2013
HIGH PRESSURE OVER CENTRAL CANADA WILL KEEP A RIDGE OVER THE UPPER
GREAT LAKES REGION TODAY. BUT AS A LOW PRESSURE SYSTEM
DEPARTS THE CENTRAL PLAINS AND MOVES THROUGH THE OHIO RIVER VALLEY
THROUGH MONDAY NIGHT...THE RIDGE WILL WEAKEN AND SHIFT WEST. THIS
WILL LEAD TO PERSISTENT NORTHERLY FLOW ACROSS THE AREA...ALTHOUGH
THE WINDS SHOULD BE AT OR BELOW 25 KNOTS. AS THE LOW SHIFTS OFF
THE ATLANTIC SEABOARD ON TUESDAY...HIGH PRESSURE WILL BEGIN TO SHIFT
BACK TO THE EAST AND COVER THE UPPER GREAT LAKES FROM TUESDAY NIGHT
THROUGH THE REST OF THE WORK WEEK. THIS WILL KEEP THE NORTHERLY
WINDS BELOW 15KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...MCD
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
744 AM EDT SUN MAR 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 502 AM EDT SUN MAR 24 2013
WV IMAGERY AND RUC ANALYSIS INDICATED PERSISTENT HIGH LATITUDE
MID/UPPER LEVEL RIDGING FROM SCANDINAVIA INTO NORTHERN CANADA
RESULTING IN LOWER HEIGHTS AND COLDER AIR TO THE SOUTH ACROSS SRN
CANADA AND THE NRN CONUS. A WEAK RIDGE EXTENDED ACROSS THE WRN
GREAT LAKES BTWN MID LEVEL LOWS OVER THE DAKOTAS AND CANADIAN
MARATIMES. AT THE SFC...WEAK NE FLOW PREVAILED BETWEEN HIGH PRES
OVER SASK INTO NRN MANITOBA AND LOW PRES OVER THE LOWER MS VALLEY.
IR SATELLITE LOOP SHOWED AN EXTENSIVE AREA OF CLOUDS ACROSS THE
REGION WITH A RELATIVELY SMALL CLEAR AREA NE OF LAKE SUPERIOR.
WITH GENERALLY WEAK ONSHORE WINDS INTO NRN UPPER MI
OVERNIGHT...RADAR INDICATED NO PCPN. HOWEVER...AS WINDS INCREASE OUT
OF THE NORTHEAST AND 850 MB TEMPS REMAIN NER -11C...EXPECT SOME
LIGHT SNOW MAY STILL DEVELOP OVER THE WEST AND N CNTRL LOCATIONS
WHERE UPSLOPE FLOW PREVAILS. SINCE TEMPS IN THE MOIST LAYER REMAINED
BORDERLINE TO SUPPORT ICE CRYSTALS...A MIX OF -SN/FLURRIES/-FZDZ MAY
BE POSSIBLE. MODELS SUGGEST THAT THE DRY AIR TO THE NORTHEAST WILL
SPREAD ACROSS LAKE SUPERIOR INTO UPPER MI THIS AFTERNOON. THIS
SHOULD BRING AN END TO ANY PCPN THAT DEVELOPS EARLY TODAY. SOME
CLEARING MAY ALSO SPREAD FROM EAST INTO CNTRL UPPER MI BY LATE THIS
AFTERNOON WHICH SHOULD HELP BOOST TEMPS INTO THE LOWER TO MID 30S.
THE MODELS WERE CONSISTENT IN BRINGING ANOTHER BATCH OF 925-700 MB
MOISTURE INTO THE AREA FROM THE NORTHEAST TONIGHT. THIS WILL BRING
INCREASING CHANCES FOR LIGHT LAKE EFFECT SNOW...ESPECIALLY AFT
06Z...TO AREAS FAVORED BY UPSLOPE NNE FLOW IN N CNTRL AND WRN UPPER
MI. SINCE DEEPER MOISTURE TO AROUND -12C IS LIKELY...-FZDZ CHANCES
WILL BE REDUCED. THE CLOUDS WILL ALSO KEEP TEMPS FROM FALLING OFF
TOO MUCH WITH MIN READINGS AGAIN ABOVE NORMAL....IN THE LOW TO MID
20S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 443 AM EDT SUN MAR 24 2013
OUR STEADY NORTHERLY FLOW OFF LAKE SUPERIOR WILL CONTINUE THROUGH
WEDNESDAY...WITH LIGHT PRECIPITATION POSSIBLE NEARLY EVERY DAY NEAR
LAKE SUPERIOR. LOOK FOR TEMPERATURES TO SLOWLY INCREASE EACH
DAY...WITH SOUTH CENTRAL AREAS NEARING 40 DEGREES FOR A HIGH ON
THURSDAY...AND REMAINING IN THE UPPER 30S AND LOW 40S TO WRAP UP THE
WORK WEEK AND START THE UPCOMING WEEKEND.
THE NEXT GOOD SURGE OF PRECIPITATION WILL BE MONDAY THROUGH TUESDAY
MORNING...AS THE MID ATLANTIC LOW ROTATES MOISTURE BACK TOWARD THE
UPPER GREAT LAKES REGION. STILL IT WILL BE SET UP AOB ABOUT
800MB...WITH THE DGZ HOVERING AT THE TOP OF THIS MOISTURE LAYER TO
AROUND 600MB. WHILE THE MOST PRISTINE SNOW CRYSTALS WILL NOT BE
EXPECTED...850MB TEMPS HOVERING BETWEEN -10 AND -12C. SNOW AMOUNTS
AROUND A HALF INCH EVERY 6 HOURS WILL BE POSSIBLE MONDAY THROUGH
TUESDAY MORNING...HIGHEST OVER THE ELEVATED TERRAIN OF MARQUETTE
COUNTY...AND ACROSS WESTERN GOGEBIC AND ONTONAGON COUNTIES.
THE 500MB TROUGH WILL LIKELY REMAIN ENTRENCHED ACROSS CENTRAL AND
EASTERN UPPER MICHIGAN THROUGH TUESDAY NIGHT INTO WEDNESDAY. AT THAT
POINT NW FLOW LOOKS TO TAKE OVER ALOFT...WITH A SERIES OF WEAKER
WAVES SLIDING NEAR THE UPPER GREAT LAKES. WHILE WE DO HAVE SLIGHT
CHANCE POPS MENTIONED FOR DAY 5/FRIDAY INTO DAY 6/SATURDAY...THE
CONFIDENCE IS VERY LOW. THE ECMWF KEEP LOW PRESSURE STUCK UP NEAR
JAMES BAY AND HUDSON BAY ON FRIDAY...WITH HIGH PRESSURE STRETCHING
FROM SOUTH CENTRAL CANADA THROUGH THE UPPER GREAT LAKES. A WEAK COLD
FRONT MAY CROSS THURSDAY NIGHT INTO FRIDAY. THE 00Z MODEL RUNS LOOK
LESS THAN IMPRESSIVE WITH THE CHANCE FOR MEASURABLE PRECIP THROUGH
THE END OF THE FORECAST PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 743 AM EDT SUN MAR 24 2013
MVFR CONDITIONS THIS MORNING WITH SOME OCNL FLURRIES OR FREEZING
DRIZZLE WHERE UPSLOPE NNE FLOW PREVAILS AT CMX/SAW. CLOUDS AND ANY
PCPN IS EXPECTED TO END THIS AFTERNOON AS DRIER AIR
BUILDS INTO THE AREA AS STRONGER AND DEEPER NE FLOW SPREADS ACROSS
THE AREA. SITES MAY IMPROVE TO VFR BY LATE SUN AFTN OR SUN EVENING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 502 AM EDT SUN MAR 24 2013
HIGH PRESSURE OVER CENTRAL CANADA WILL KEEP A RIDGE OVER THE UPPER
GREAT LAKES REGION TODAY. BUT AS A LOW PRESSURE SYSTEM
DEPARTS THE CENTRAL PLAINS AND MOVES THROUGH THE OHIO RIVER VALLEY
THROUGH MONDAY NIGHT...THE RIDGE WILL WEAKEN AND SHIFT WEST. THIS
WILL LEAD TO PERSISTENT NORTHERLY FLOW ACROSS THE AREA...ALTHOUGH
THE WINDS SHOULD BE AT OR BELOW 25 KNOTS. AS THE LOW SHIFTS OFF
THE ATLANTIC SEABOARD ON TUESDAY...HIGH PRESSURE WILL BEGIN TO SHIFT
BACK TO THE EAST AND COVER THE UPPER GREAT LAKES FROM TUESDAY NIGHT
THROUGH THE REST OF THE WORK WEEK. THIS WILL KEEP THE NORTHERLY
WINDS BELOW 15KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
503 AM EDT SUN MAR 24 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 502 AM EDT SUN MAR 24 2013
WV IMAGERY AND RUC ANALYSIS INDICATED PERSISTENT HIGH LATITUDE
MID/UPPER LEVEL RIDGING FROM SCANDINAVIA INTO NORTHERN CANADA
RESULTING IN LOWER HEIGHTS AND COLDER AIR TO THE SOUTH ACROSS SRN
CANADA AND THE NRN CONUS. A WEAK RIDGE EXTENDED ACROSS THE WRN
GREAT LAKES BTWN MID LEVEL LOWS OVER THE DAKOTAS AND CANADIAN
MARATIMES. AT THE SFC...WEAK NE FLOW PREVAILED BETWEEN HIGH PRES
OVER SASK INTO NRN MANITOBA AND LOW PRES OVER THE LOWER MS VALLEY.
IR SATELLITE LOOP SHOWED AN EXTENSIVE AREA OF CLOUDS ACROSS THE
REGION WITH A RELATIVELY SMALL CLEAR AREA NE OF LAKE SUPERIOR.
WITH GENERALLY WEAK ONSHORE WINDS INTO NRN UPPER MI
OVERNIGHT...RADAR INDICATED NO PCPN. HOWEVER...AS WINDS INCREASE OUT
OF THE NORTHEAST AND 850 MB TEMPS REMAIN NER -11C...EXPECT SOME
LIGHT SNOW MAY STILL DEVELOP OVER THE WEST AND N CNTRL LOCATIONS
WHERE UPSLOPE FLOW PREVAILS. SINCE TEMPS IN THE MOIST LAYER REMAINED
BORDERLINE TO SUPPORT ICE CRYSTALS...A MIX OF -SN/FLURRIES/-FZDZ MAY
BE POSSIBLE. MODELS SUGGEST THAT THE DRY AIR TO THE NORTHEAST WILL
SPREAD ACROSS LAKE SUPERIOR INTO UPPER MI THIS AFTERNOON. THIS
SHOULD BRING AN END TO ANY PCPN THAT DEVELOPS EARLY TODAY. SOME
CLEARING MAY ALSO SPREAD FROM EAST INTO CNTRL UPPER MI BY LATE THIS
AFTERNOON WHICH SHOULD HELP BOOST TEMPS INTO THE LOWER TO MID 30S.
THE MODELS WERE CONSISTENT IN BRINGING ANOTHER BATCH OF 925-700 MB
MOISTURE INTO THE AREA FROM THE NORTHEAST TONIGHT. THIS WILL BRING
INCREASING CHANCES FOR LIGHT LAKE EFFECT SNOW...ESPECIALLY AFT
06Z...TO AREAS FAVORED BY UPSLOPE NNE FLOW IN N CNTRL AND WRN UPPER
MI. SINCE DEEPER MOISTURE TO AROUND -12C IS LIKELY...-FZDZ CHANCES
WILL BE REDUCED. THE CLOUDS WILL ALSO KEEP TEMPS FROM FALLING OFF
TOO MUCH WITH MIN READINGS AGAIN ABOVE NORMAL....IN THE LOW TO MID
20S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 443 AM EDT SUN MAR 24 2013
OUR STEADY NORTHERLY FLOW OFF LAKE SUPERIOR WILL CONTINUE THROUGH
WEDNESDAY...WITH LIGHT PRECIPITATION POSSIBLE NEARLY EVERY DAY NEAR
LAKE SUPERIOR. LOOK FOR TEMPERATURES TO SLOWLY INCREASE EACH
DAY...WITH SOUTH CENTRAL AREAS NEARING 40 DEGREES FOR A HIGH ON
THURSDAY...AND REMAINING IN THE UPPER 30S AND LOW 40S TO WRAP UP THE
WORK WEEK AND START THE UPCOMING WEEKEND.
THE NEXT GOOD SURGE OF PRECIPITATION WILL BE MONDAY THROUGH TUESDAY
MORNING...AS THE MID ATLANTIC LOW ROTATES MOISTURE BACK TOWARD THE
UPPER GREAT LAKES REGION. STILL IT WILL BE SET UP AOB ABOUT
800MB...WITH THE DGZ HOVERING AT THE TOP OF THIS MOISTURE LAYER TO
AROUND 600MB. WHILE THE MOST PRISTINE SNOW CRYSTALS WILL NOT BE
EXPECTED...850MB TEMPS HOVERING BETWEEN -10 AND -12C. SNOW AMOUNTS
AROUND A HALF INCH EVERY 6 HOURS WILL BE POSSIBLE MONDAY THROUGH
TUESDAY MORNING...HIGHEST OVER THE ELEVATED TERRAIN OF MARQUETTE
COUNTY...AND ACROSS WESTERN GOGEBIC AND ONTONAGON COUNTIES.
THE 500MB TROUGH WILL LIKELY REMAIN ENTRENCHED ACROSS CENTRAL AND
EASTERN UPPER MICHIGAN THROUGH TUESDAY NIGHT INTO WEDNESDAY. AT THAT
POINT NW FLOW LOOKS TO TAKE OVER ALOFT...WITH A SERIES OF WEAKER
WAVES SLIDING NEAR THE UPPER GREAT LAKES. WHILE WE DO HAVE SLIGHT
CHANCE POPS MENTIONED FOR DAY 5/FRIDAY INTO DAY 6/SATURDAY...THE
CONFIDENCE IS VERY LOW. THE ECMWF KEEP LOW PRESSURE STUCK UP NEAR
JAMES BAY AND HUDSON BAY ON FRIDAY...WITH HIGH PRESSURE STRETCHING
FROM SOUTH CENTRAL CANADA THROUGH THE UPPER GREAT LAKES. A WEAK COLD
FRONT MAY CROSS THURSDAY NIGHT INTO FRIDAY. THE 00Z MODEL RUNS LOOK
LESS THAN IMPRESSIVE WITH THE CHANCE FOR MEASURABLE PRECIP THROUGH
THE END OF THE FORECAST PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 133 AM EDT SUN MAR 24 2013
MVFR CONDITIONS SHOULD GENERALLY PREVAIL THROUGHOUT THE NIGHT AND
INTO SUNDAY MORNING WITH NORTH TO NORTHEAST FLOW ACROSS THE REGION.
LATEST SATELLITE IMAGERY SUGGESTS SOME BREAKS IN THE CLOUDS NEAR CMX
AND IWD WHICH MAY KEEP BRIEF PERIODS OF VFR FOR THE NEXT HOUR OR
SO...BUT IN GENERAL CONDITIONS SHOULD REMAIN MVFR. THE UPSLOPE FLOW
COMBINED WITH THE LOW LEVEL MOISTURE THAT HAS BEEN IN PLACE FOR THE
LAST SEVERAL DAYS SHOULD ALLOW FOR SOME FREEZING DRIZZLE TO DEVELOP
OVERNIGHT...ESPECIALLY AT SAW WHERE N-NE FLOW IS HIGHLY FAVORABLE
FOR UPSLOPE FREEZING DRIZZLE. SOME SLIGHT IMPROVEMENT LATER IN THE
DAY ON SUNDAY AS DRIER AIR BUILDS INTO THE AREA AS STRONGER AND
DEEPER NE FLOW SPREADS ACROSS THE AREA. SITES MAY IMPROVE TO VFR BY
LATE SUN AFTN OR SUN EVENING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 502 AM EDT SUN MAR 24 2013
HIGH PRESSURE OVER CENTRAL CANADA WILL KEEP A RIDGE OVER THE UPPER
GREAT LAKES REGION TODAY. BUT AS A LOW PRESSURE SYSTEM
DEPARTS THE CENTRAL PLAINS AND MOVES THROUGH THE OHIO RIVER VALLEY
THROUGH MONDAY NIGHT...THE RIDGE WILL WEAKEN AND SHIFT WEST. THIS
WILL LEAD TO PERSISTENT NORTHERLY FLOW ACROSS THE AREA...ALTHOUGH
THE WINDS SHOULD BE AT OR BELOW 25 KNOTS. AS THE LOW SHIFTS OFF
THE ATLANTIC SEABOARD ON TUESDAY...HIGH PRESSURE WILL BEGIN TO SHIFT
BACK TO THE EAST AND COVER THE UPPER GREAT LAKES FROM TUESDAY NIGHT
THROUGH THE REST OF THE WORK WEEK. THIS WILL KEEP THE NORTHERLY
WINDS BELOW 15KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...MRD
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
443 AM EDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 858 PM EDT SAT MAR 23 2013
NO MAJOR CHANGES TO THE GOING FORECAST. OVERNIGHT SHIFT WILL NEED TO
WATCH FOR HEAVIER FREEZING DRIZZLE IN THE UPSLOPE AREAS OF NORTH
CENTRAL UPPER MICHIGAN. THE 18Z NAM AND 21Z RAP BOTH SUGGEST A
PERIOD OF MODERATE UPWARD MOTION AS THE UPSLOPE FLOW INCREASES WHEN
THE PBL WINDS BECOME N-NE. BOTH OF THESE MODELS SHOW A SATURATED
LAYER BETWEEN -6 AND -12C WHICH WOULD INDICATE THAT MOSTLY
SUPERCOOLED WATER WITH VERY LITTLE ICE NUCLEATION. IN FACT...THIS IS
WHAT HAS BEEN SEEN AT THE OFFICE THIS EVENING AND HAS ALLOWED FOR A
GLAZE ON ELEVATED SURFACES. HAVE OPTED TO ISSUE TO SPECIAL WEATHER
STATEMENT TO ACCOUNT FOR POTENTIAL SLIPPERY ROADS OVERNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 353 PM EDT SAT MAR 23 2013
DON/T EXPECT THE WEATHER TO BE MUCH DIFFERENT THAN THE LAST DAY OR
TWO. THIS OVERALL QUIET PATTERN IS DUE TO THE STRONG NEGATIVE NAO
BLOCKING PATTERN PUSHING THE JET STREAM FARTHER SOUTH AND KEEPING
THE STORM TRACK WELL TO THE SOUTH OF THE AREA. THE MAIN SYSTEM TO
BE AFFECTING LOCATIONS WELL TO THE SOUTH OF OUR CWA WILL MOVE FROM
CENTRAL PLAINS THIS AFTERNOON TO THE OHIO RIVER VALLEY ON SUNDAY.
WHILE THIS SYSTEM TRACKS TO THE SOUTH...NORTHEASTERLY FLOW ALOFT
WILL KEEP THE COLDER 850MB TEMPS...AROUND -11C OR 4-6
DEGREES BELOW NORMAL...OVER THE AREA DURING THE SHORT TERM PERIOD.
THE MOISTURE OVER THE AREA IS FAIRLY SHALLOW...AROUND
975-900MB...FOR TONIGHT AND SUNDAY MORNING BEFORE A POCKET OF DRIER
AIR ARRIVES ON SUNDAY AFTERNOON FROM THE NORTHEAST. SKIES MAY
SCATTER OUT A LITTLE BIT BASED OFF SOME OF THE GAPS OVER
LAKE SUPERIOR AND WITH THE LOSS OF DIURNAL HEATING...BUT WITH
CLOUDS MAKING THEIR WAY SOUTH OVER THE NORTHERN LAKE AND MODELS
SHOWING DECENT MOISTURE PRESENT...WOULD EXPECT CLOUDS TO QUICKLY
FILL BACK IN TONIGHT. THUS...EXPECT MOSTLY CLOUDY CONDITIONS TO
AFFECT THE AREA TONIGHT INTO SUNDAY MORNING...BUT AS THE DRIER AIR
WORKS IN FROM THE NORTHEAST ON SUNDAY...A DECREASING CLOUD TREND IS
EXPECTED THROUGH THE LATER AFTERNOON HOURS OVER THE NORTHEAST
HALF OF THE CWA.
AS FOR PRECIPITATION...WOULD EXPECT IT TO BE SIMILAR TO THE LAST TWO
DAYS WHERE IT PEAKS UP DURING THE OVERNIGHT HOURS DUE TO REDUCED
MIXING. THIS IS ESPECIALLY TRUE IN THE NORTHEAST WIND FAVORED
LOCATIONS DUE TO WINDS VEERING FROM A MORE VARIABLE NORTHERLY
DIRECTION LATE THIS AFTERNOON TO A PERSISTENT NORTHEAST DIRECTION
TONIGHT WITH THE WEAKENING HIGH PRESSURE RIDGE AND LOW EXITING THE
CENTRAL PLAINS. BUMPED UP POPS TO CHANCES OVER THE HIGHER TERRAIN OF
THE NORTH CENTRAL LATE TONIGHT BASED ON ALL OF THE HIGHER RESOLUTION
MODELS PICKING UP ON THE UPSLOPE FORCING AND INCREASED 950-925MB
OMEGA. WITH THE DRIER AIR LIKELY ARRIVING ON LATE
SUNDAY MORNING...WOULD EXPECT IT TO COME TO AN END FAIRLY QUICKLY ON
SUNDAY AFTERNOON. SINCE CLOUD IS STILL LOCATED IN THE BORDERLINE
ICE CRYSTAL REGION...WILL CONTINUE TO MENTION FREEZING DRIZZLE
ALONG WITH THE SNOW TONIGHT INTO SUNDAY MORNING. FINALLY...DID ADD A
FEW FLURRIES OVER THE INTERIOR WEST DUE TO DIURNAL HEATING
INCREASING THE LOW LEVEL LAPSE RATES AND POTENTIALLY LEADING TO SOME
LIGHT FLURRIES TOWARDS THE AFTERNOON WITH THE LINGER MOISTURE.
LOWS TONIGHT WILL DEPEND ON CLOUD COVER AND THINK THE COOLEST
LOCATIONS WILL BE OVER THE EASTERN CWA. LAST NIGHT...WHERE IT
CLEARED OUT OVER THE EAST...LOCATIONS FELL INTO THE SINGLE DIGITS
ABOVE ZERO. HAVE FOLLOWED THAT IDEA FOR SPINCICH LAKE...BUT BANKED
ON MORE CLOUDS OVER THE REST OF THE AREA AND WENT WITH UPPER TEENS
OR LOWER 20S. HIGHS ON SUNDAY SHOULDN/T BE MUCH DIFFERENT THAN
TODAY AND WILL CONTINUE TO MENTION LOW TO MID 30S.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 443 AM EDT SUN MAR 24 2013
OUR STEADY NORTHERLY FLOW OFF LAKE SUPERIOR WILL CONTINUE THROUGH
WEDNESDAY...WITH LIGHT PRECIPITATION POSSIBLE NEARLY EVERY DAY NEAR
LAKE SUPERIOR. LOOK FOR TEMPERATURES TO SLOWLY INCREASE EACH
DAY...WITH SOUTH CENTRAL AREAS NEARING 40 DEGREES FOR A HIGH ON
THURSDAY...AND REMAINING IN THE UPPER 30S AND LOW 40S TO WRAP UP THE
WORK WEEK AND START THE UPCOMING WEEKEND.
THE NEXT GOOD SURGE OF PRECIPITATION WILL BE MONDAY THROUGH TUESDAY
MORNING...AS THE MID ATLANTIC LOW ROTATES MOISTURE BACK TOWARD THE
UPPER GREAT LAKES REGION. STILL IT WILL BE SET UP AOB ABOUT
800MB...WITH THE DGZ HOVERING AT THE TOP OF THIS MOISTURE LAYER TO
AROUND 600MB. WHILE THE MOST PRISTINE SNOW CRYSTALS WILL NOT BE
EXPECTED...850MB TEMPS HOVERING BETWEEN -10 AND -12C. SNOW AMOUNTS
AROUND A HALF INCH EVERY 6 HOURS WILL BE POSSIBLE MONDAY THROUGH
TUESDAY MORNING...HIGHEST OVER THE ELEVATED TERRAIN OF MARQUETTE
COUNTY...AND ACROSS WESTERN GOGEBIC AND ONTONAGON COUNTIES.
THE 500MB TROUGH WILL LIKELY REMAIN ENTRENCHED ACROSS CENTRAL AND
EASTERN UPPER MICHIGAN THROUGH TUESDAY NIGHT INTO WEDNESDAY. AT THAT
POINT NW FLOW LOOKS TO TAKE OVER ALOFT...WITH A SERIES OF WEAKER
WAVES SLIDING NEAR THE UPPER GREAT LAKES. WHILE WE DO HAVE SLIGHT
CHANCE POPS MENTIONED FOR DAY 5/FRIDAY INTO DAY 6/SATURDAY...THE
CONFIDENCE IS VERY LOW. THE ECMWF KEEP LOW PRESSURE STUCK UP NEAR
JAMES BAY AND HUDSON BAY ON FRIDAY...WITH HIGH PRESSURE STRETCHING
FROM SOUTH CENTRAL CANADA THROUGH THE UPPER GREAT LAKES. A WEAK COLD
FRONT MAY CROSS THURSDAY NIGHT INTO FRIDAY. THE 00Z MODEL RUNS LOOK
LESS THAN IMPRESSIVE WITH THE CHANCE FOR MEASURABLE PRECIP THROUGH
THE END OF THE FORECAST PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 133 AM EDT SUN MAR 24 2013
MVFR CONDITIONS SHOULD GENERALLY PREVAIL THROUGHOUT THE NIGHT AND
INTO SUNDAY MORNING WITH NORTH TO NORTHEAST FLOW ACROSS THE REGION.
LATEST SATELLITE IMAGERY SUGGESTS SOME BREAKS IN THE CLOUDS NEAR CMX
AND IWD WHICH MAY KEEP BRIEF PERIODS OF VFR FOR THE NEXT HOUR OR
SO...BUT IN GENERAL CONDITIONS SHOULD REMAIN MVFR. THE UPSLOPE FLOW
COMBINED WITH THE LOW LEVEL MOISTURE THAT HAS BEEN IN PLACE FOR THE
LAST SEVERAL DAYS SHOULD ALLOW FOR SOME FREEZING DRIZZLE TO DEVELOP
OVERNIGHT...ESPECIALLY AT SAW WHERE N-NE FLOW IS HIGHLY FAVORABLE
FOR UPSLOPE FREEZING DRIZZLE. SOME SLIGHT IMPROVEMENT LATER IN THE
DAY ON SUNDAY AS DRIER AIR BUILDS INTO THE AREA AS STRONGER AND
DEEPER NE FLOW SPREADS ACROSS THE AREA. SITES MAY IMPROVE TO VFR BY
LATE SUN AFTN OR SUN EVENING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 353 PM EDT SAT MAR 23 2013
A HIGH PRESSURE OVER CENTRAL CANADA WILL KEEP A RIDGE OVER THE
UPPER GREAT LAKES REGION INTO SUNDAY MONRING. BUT AS A LOW PRESSURE
SYSTEM DEPARTS THE CENTRAL PLAINS AND MOVES THROUGH THE OHIO RIVER
VALLEY THROUGH MONDAY NIGHT...THE RIDGE WILL WEAKEN AND SHIFT WEST.
THIS WILL LEAD TO PERSISTENT NORTHERLY FLOW ACROSS THE
AREA...ALTHOUGH THE WINDS SHOULD BE LESS THAN 25 KNOTS. AS THE
LOW SHIFTS OFF THE ATLANTIC SEABOARD ON TUESDAY...HIGH PRESSURE
WILL BEGIN TO SHIFT BACK TO THE EAST AND COVER THE UPPER GREAT
LAKES FROM TUESDAY NIGHT THROUGH THE REST OF THE WORK WEEK. THIS
WILL KEEP THE NORTHERLY WINDS BELOW 15KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...MRD
SHORT TERM...SRF
LONG TERM...KF
AVIATION...MRD
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
134 AM EDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 858 PM EDT SAT MAR 23 2013
NO MAJOR CHANGES TO THE GOING FORECAST. OVERNIGHT SHIFT WILL NEED TO
WATCH FOR HEAVIER FREEZING DRIZZLE IN THE UPSLOPE AREAS OF NORTH
CENTRAL UPPER MICHIGAN. THE 18Z NAM AND 21Z RAP BOTH SUGGEST A
PERIOD OF MODERATE UPWARD MOTION AS THE UPSLOPE FLOW INCREASES WHEN
THE PBL WINDS BECOME N-NE. BOTH OF THESE MODELS SHOW A SATURATED
LAYER BETWEEN -6 AND -12C WHICH WOULD INDICATE THAT MOSTLY
SUPERCOOLED WATER WITH VERY LITTLE ICE NUCLEATION. IN FACT...THIS IS
WHAT HAS BEEN SEEN AT THE OFFICE THIS EVENING AND HAS ALLOWED FOR A
GLAZE ON ELEVATED SURFACES. HAVE OPTED TO ISSUE TO SPECIAL WEATHER
STATEMENT TO ACCOUNT FOR POTENTIAL SLIPPERY ROADS OVERNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 353 PM EDT SAT MAR 23 2013
DON/T EXPECT THE WEATHER TO BE MUCH DIFFERENT THAN THE LAST DAY OR
TWO. THIS OVERALL QUIET PATTERN IS DUE TO THE STRONG NEGATIVE NAO
BLOCKING PATTERN PUSHING THE JET STREAM FARTHER SOUTH AND KEEPING
THE STORM TRACK WELL TO THE SOUTH OF THE AREA. THE MAIN SYSTEM TO
BE AFFECTING LOCATIONS WELL TO THE SOUTH OF OUR CWA WILL MOVE FROM
CENTRAL PLAINS THIS AFTERNOON TO THE OHIO RIVER VALLEY ON SUNDAY.
WHILE THIS SYSTEM TRACKS TO THE SOUTH...NORTHEASTERLY FLOW ALOFT
WILL KEEP THE COLDER 850MB TEMPS...AROUND -11C OR 4-6
DEGREES BELOW NORMAL...OVER THE AREA DURING THE SHORT TERM PERIOD.
THE MOISTURE OVER THE AREA IS FAIRLY SHALLOW...AROUND
975-900MB...FOR TONIGHT AND SUNDAY MORNING BEFORE A POCKET OF DRIER
AIR ARRIVES ON SUNDAY AFTERNOON FROM THE NORTHEAST. SKIES MAY
SCATTER OUT A LITTLE BIT BASED OFF SOME OF THE GAPS OVER
LAKE SUPERIOR AND WITH THE LOSS OF DIURNAL HEATING...BUT WITH
CLOUDS MAKING THEIR WAY SOUTH OVER THE NORTHERN LAKE AND MODELS
SHOWING DECENT MOISTURE PRESENT...WOULD EXPECT CLOUDS TO QUICKLY
FILL BACK IN TONIGHT. THUS...EXPECT MOSTLY CLOUDY CONDITIONS TO
AFFECT THE AREA TONIGHT INTO SUNDAY MORNING...BUT AS THE DRIER AIR
WORKS IN FROM THE NORTHEAST ON SUNDAY...A DECREASING CLOUD TREND IS
EXPECTED THROUGH THE LATER AFTERNOON HOURS OVER THE NORTHEAST
HALF OF THE CWA.
AS FOR PRECIPITATION...WOULD EXPECT IT TO BE SIMILAR TO THE LAST TWO
DAYS WHERE IT PEAKS UP DURING THE OVERNIGHT HOURS DUE TO REDUCED
MIXING. THIS IS ESPECIALLY TRUE IN THE NORTHEAST WIND FAVORED
LOCATIONS DUE TO WINDS VEERING FROM A MORE VARIABLE NORTHERLY
DIRECTION LATE THIS AFTERNOON TO A PERSISTENT NORTHEAST DIRECTION
TONIGHT WITH THE WEAKENING HIGH PRESSURE RIDGE AND LOW EXITING THE
CENTRAL PLAINS. BUMPED UP POPS TO CHANCES OVER THE HIGHER TERRAIN OF
THE NORTH CENTRAL LATE TONIGHT BASED ON ALL OF THE HIGHER RESOLUTION
MODELS PICKING UP ON THE UPSLOPE FORCING AND INCREASED 950-925MB
OMEGA. WITH THE DRIER AIR LIKELY ARRIVING ON LATE
SUNDAY MORNING...WOULD EXPECT IT TO COME TO AN END FAIRLY QUICKLY ON
SUNDAY AFTERNOON. SINCE CLOUD IS STILL LOCATED IN THE BORDERLINE
ICE CRYSTAL REGION...WILL CONTINUE TO MENTION FREEZING DRIZZLE
ALONG WITH THE SNOW TONIGHT INTO SUNDAY MORNING. FINALLY...DID ADD A
FEW FLURRIES OVER THE INTERIOR WEST DUE TO DIURNAL HEATING
INCREASING THE LOW LEVEL LAPSE RATES AND POTENTIALLY LEADING TO SOME
LIGHT FLURRIES TOWARDS THE AFTERNOON WITH THE LINGER MOISTURE.
LOWS TONIGHT WILL DEPEND ON CLOUD COVER AND THINK THE COOLEST
LOCATIONS WILL BE OVER THE EASTERN CWA. LAST NIGHT...WHERE IT
CLEARED OUT OVER THE EAST...LOCATIONS FELL INTO THE SINGLE DIGITS
ABOVE ZERO. HAVE FOLLOWED THAT IDEA FOR SPINCICH LAKE...BUT BANKED
ON MORE CLOUDS OVER THE REST OF THE AREA AND WENT WITH UPPER TEENS
OR LOWER 20S. HIGHS ON SUNDAY SHOULDN/T BE MUCH DIFFERENT THAN
TODAY AND WILL CONTINUE TO MENTION LOW TO MID 30S.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 353 PM EDT SAT MAR 23 2013
SUN NIGHT AND MON...AS A MID-LEVEL AND SFC LOW MOVES THROUGH THE
OHIO VALLEY REACHING THE MID-ATLANTIC COAST MONDAY
AFTERNOON...MODELS SUGGEST INCREASING 850-700 MB MOISTURE WILL BE
DRAWN TOWARD UPPER MICHIGAN FROM THE NORTHEAST. THE INCREASED
MOISTURE COMBINED WITH NNE FLOW AND 850 MB TEMPS REMAINING IN THE
-10C TO -11C RANGE WILL BE ENOUGH TO SUPPORT AT LEAST SCT SNOW
SHOWERS INTO THE WEST AND N CNTRL PORTIONS OF THE CWA. ANY LOCAL
SNOWFALL ACCUMULATIONS FM THESE SHOWERS SHOULD REMAIN LIGHT...AROUND
A HALF INCH OR LESS PER 12 HRS.
TUE...MOISTURE TO NEAR 800 MB IN THE MORNING AND 850 MB TEMPS
LINGERING IN THE -10 TO -12C RANGE...SHOULD STILL RESULT IN
SCT/ISOLD -SHSN WEST AND N CNTRL COUNTIES IN THE MORNING WITH NRLY
FLOW. EXPECT THE PCPN TO DIMINISH DURING THE AFTERNOON ESPECIALLY
NCNTRL WHERE SIGNIFICANT 850-700 MB DRYING IS EXPECTED...PER
GFS/ECMWF MOISTURE FCST.
WED AND THU...WITH WEAK MID LEVEL AND SFC RIDGING EXPECTED AND
DRYING/SUBSIDENCE NOTED ON MODEL SNDGS...LOOK FOR DRY CONDITIONS
WITH GREATER SUNSHINE AS HIGH TEMPS SLOWLY MODERATE INTO THE MID TO
UPPER 30S BY THU.
FRI AND SAT...THE 12Z GFS...ECMWF AND GEM-NH HAVE ALL TRENDED
FARTHER SOUTH WITH COMPACT MID LEVEL LOW APPROACHING FM SOUTH
CENTRAL CANADA AND MOVING ACROSS THE NRN PORTION OF LAKE SUPERIOR
FRI AFTERNOON INTO SATURDAY. GIVEN THE WEAK TO MODERATE Q-VECT CONV
SPREADING INTO THE AREA ALONG THE ASSOCIATED COLD FRONT HAVE DECIDED
TO INTRODUCE SLIGHT CHC POPS FOR FRIDAY INTO SATURDAY. WEAK CAA
BEHIND THE FRONT COULD ALSO CONTRIBUTE TO LIGHT SCT LAKE EFFECT SNOW
SHOWERS FRIDAY NIGHT INTO SATURDAY ACROSS THE NRN TIER AND ERN
COUNTIES IN NW FLOW. ONLY SLIGHT CHC POPS WARRANTED AT THIS TIME AS
THIS IS THE FIRST MODEL RUN TO SHOW THE FARTHER SOUTH TRACK WITH
CANADIAN MID-LVL LOW. IF MODELS CONTINUE TO TREND FARTHER SOUTH WITH
THIS SYSTEM...THEN POPS EVENTUALLY WILL NEED TO INCREASED FOR LATE
NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 133 AM EDT SUN MAR 24 2013
MVFR CONDITIONS SHOULD GENERALLY PREVAIL THROUGHOUT THE NIGHT AND
INTO SUNDAY MORNING WITH NORTH TO NORTHEAST FLOW ACROSS THE REGION.
LATEST SATELLITE IMAGERY SUGGESTS SOME BREAKS IN THE CLOUDS NEAR CMX
AND IWD WHICH MAY KEEP BRIEF PERIODS OF VFR FOR THE NEXT HOUR OR
SO...BUT IN GENERAL CONDITIONS SHOULD REMAIN MVFR. THE UPSLOPE FLOW
COMBINED WITH THE LOW LEVEL MOISTURE THAT HAS BEEN IN PLACE FOR THE
LAST SEVERAL DAYS SHOULD ALLOW FOR SOME FREEZING DRIZZLE TO DEVELOP
OVERNIGHT...ESPECIALLY AT SAW WHERE N-NE FLOW IS HIGHLY FAVORABLE
FOR UPSLOPE FREEZING DRIZZLE. SOME SLIGHT IMPROVEMENT LATER IN THE
DAY ON SUNDAY AS DRIER AIR BUILDS INTO THE AREA AS STRONGER AND
DEEPER NE FLOW SPREADS ACROSS THE AREA. SITES MAY IMPROVE TO VFR BY
LATE SUN AFTN OR SUN EVENING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 353 PM EDT SAT MAR 23 2013
A HIGH PRESSURE OVER CENTRAL CANADA WILL KEEP A RIDGE OVER THE
UPPER GREAT LAKES REGION INTO SUNDAY MONRING. BUT AS A LOW PRESSURE
SYSTEM DEPARTS THE CENTRAL PLAINS AND MOVES THROUGH THE OHIO RIVER
VALLEY THROUGH MONDAY NIGHT...THE RIDGE WILL WEAKEN AND SHIFT WEST.
THIS WILL LEAD TO PERSISTENT NORTHERLY FLOW ACROSS THE
AREA...ALTHOUGH THE WINDS SHOULD BE LESS THAN 25 KNOTS. AS THE
LOW SHIFTS OFF THE ATLANTIC SEABOARD ON TUESDAY...HIGH PRESSURE
WILL BEGIN TO SHIFT BACK TO THE EAST AND COVER THE UPPER GREAT
LAKES FROM TUESDAY NIGHT THROUGH THE REST OF THE WORK WEEK. THIS
WILL KEEP THE NORTHERLY WINDS BELOW 15KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...MRD
SHORT TERM...SRF
LONG TERM...VOSS
AVIATION...MRD
MARINE...SRF
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1217 PM CDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 1030 AM CDT SUN MAR 24 2013
FORECAST LOOKS TO BE ON TRACK WITH MAJOR WINTER STORM IMPACTING
THE AREA TODAY INTO THIS EVENING. SOME PARTS OF CENTRAL MISSOURI
ARE ALREADY REPORTING 7+ INCHES OF SNOW ON THE GROUND...WITH MANY
REPORTS OF HEAVY SNOW AND THUNDERSNOW ALL ALONG THE I-70 CORRIDOR
IN MISSOURI. THERE HAVE ALSO BEEN MORE REPORTS OF SLEET THAN
EARLIER ANTICIPATED IN THE WARM ADVECTION PRECIP STILL ONGOING
ACROSS PARTS OF SOUTHWEST/SOUTH CENTRAL ILLINOIS. HAVE UPDATED THE
FORECAST TO ADD IN SOME SLEET IN THESE AREAS...AND A SMALL PART OF
SOUTHEAST MISSOURI. OTHERWISE...LITTLE CHANGE TO THE GOING
FORECAST AT THIS TIME.
CARNEY
&&
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 336 AM CDT SUN MAR 24 2013
PRIMARY FCST ISSUE FOR TODAY IS THE ONGOING WINTER STORM. WAA PCPN
WHICH DVLPD ACROSS THE AREA LAST NIGHT BRIEFLY CHANGED OVER TO A
RAIN/SNOW MIX AND EVEN SWITCHED OVER TO PURE SNOW IN SOME
LOCATIONS BEFORE ENDING. THERE WILL BE A BRIEF BREAK EARLY THIS
MORNING BETWEEN THE DEPARTING WAA PCPN AND THE HEAVIER SNOW
ASSOCIATED WITH THE DEFORMATION ZONE WHICH HAS ALREADY DVLPD IN
ERN KS AND WRN MO. MODELS ARE IN GENERALLY GOOD AGREEMENT THIS
MORNING WITH THE TRACK OF THE LOW PRESSURE SYSTEM...ESPECIALLY THE
ECMWF WHICH HAS BEEN FAIRLY CONSISTENT WITH THE TRACK OF THE H85
LOW ALTHOUGH THE 24/00Z RUN IS SOMEWHAT SLOWER THAN THE 23/00Z RUN
BETWEEN 12Z AND 18Z. THE TRACK OF THE H85 CIRCULATION CENTER FROM
NEAR KSGF/KUMN TO NEAR KFAM/KMDH IS VERY FAVORABLE FOR HEAVY SNOW
ACROSS THE CENTRAL PART OF THE CWA BASED ON LOCAL CLIMATOLOGY
PLOTS.
THERE ARE TWO ASPECTS OF THIS EVENT THAT REALLY CAUGHT MY
ATTENTION. FIRST...BUFKIT CROSS SECTIONS FROM A COUPLE OF MODELS
/INCLUDING THE RAP AND SREF/ SHOW VERY STRONG LIFT FOCUSED THROUGH
A RESPECTABLY DEEP DENDRITIC GROWTH ZONE WHICH IS OCCASIONALLY
SUPERSATURATED WITH RESPECT TO ICE. THIS IS ESPECIALLY TRUE
BETWEEN 15Z AND 00Z. SECOND...NO MATTER HOW YOU SLICE THE
ATMOSPHERE...THERE ARE INDICATIONS OF MODEST INSTABILITY /AT LEAST
FOR A WINTER EVENT/ ACROSS PARTS OF MO/IL TODAY. FCSTS OF H7-H5
LAPSE RATES EXCEED 7 DEG C/KM ACROSS THE SRN HALF OF THE CWA ON
THE RAP/WRF/SREF/NAM/GFS/UKMET AND EVEN THE ECMWF FCST EXCEEDS 6.5
DEG C/KM. BUFKIT SOUNDINGS ALSO SHOW UP TO 50 J/KG OF ELEVATED
CAPE AT TIMES. TAKEN TOGETHER...THESE TWO ITEMS SUGGEST THAT THERE
WILL BE PERIODS OF EFFICIENT SNOWFALL PRODUCTION WITHIN THE
DEFORMATION ZONE ALONG WITH OCCASIONAL CONVECTIVE ELEMENTS WHICH
WILL LOCALLY ENHANCE SNOWFALL RATES. IN TERMS OF SNOWFALL
AMOUNTS...IT STILL LOOKS LIKE A SOLID 6-8 INCHES OF SNOW ACROSS
THE WINTER STORM WARNING AREA WITH HIGHER AMOUNTS POSSIBLE.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 24 2013
(TONIGHT - MONDAY NIGHT)
MODELS HAVE ALL COME INTO A HARMONIOUS CONFLUENCE OF SOLUTIONS WITH
THE 00Z RUNS...WITH THE AGREED UPON TRACK MOST SIMILAR TO THE ECMWF
24HRS AGO...WITH THE GFS/NAM MORE SLY...AND THE GEM MORE NLY...AND
PLACES THIS STORM IN ABOUT THE MOST PERFECT SPOT TO MAXIMIZE SNOW
TOTALS ACROSS THE I-70 CORRIDOR WITH AN ELONGATED H850 LO TRACKING
THRU SRN MO AND SRN IL. ANOTHER TREND...THIS ONE TEMPORAL...HAS
BEEN TO SLOW DOWN THE EWD TRANSLATION OF THE STORM BY ABOUT 6HRS...
MEANING THE DEF ZONE PCPN FROM IT WILL LINGER WELL INTO THIS EVENING
FOR THE IL COUNTIES AND AREAS JUST W OF THE MS RIVER AND PERHAPS
EARLY OVERNIGHT FOR PARTS OF SWRN-SRN IL. SNOWFALL TOTALS HAVE BEEN
BUMPED UP AS A RESULT OF THE SLOWER EXIT...WITH AN ADDITIONAL 2-3"
FOR MUCH OF THE IL COUNTIES AND AROUND AN INCH MORE FOR THE REST.
HAVE EXPANDED THE REACH OF THE WARNING BACK TO THE W A BIT MORE. BY
THE TIME IT IS ALL SAID AND DONE...THE PALM SUNDAY SNOWSTORM OF 2013
IS EXPECTED TO BE ONE OF THOSE ONCE-IN-A-GENERATION TYPE STORMS FOR
OCCURRING SO LATE IN THE YEAR AND BEING SO POTENT.
THIS POTENT STORM SYSTEM WILL BE EXITING JUST AS ANOTHER...WEAKER...
SYSTEM MOVES IN. THIS SYSTEM IS THE OLD MONTANA LO THAT IS EXPECTED
TO OPEN UP LATER TODAY AND GET SUCKED IN THE UNDERTOW OF TODAY AND
THIS EVENING/S STORM SYSTEM...BECOMING SHEARED BY THE TIME IT
REACHES OUR AREA LATER TONIGHT AND CONTINUING INTO MONDAY...BUT WITH
ENOUGH TO KEEP EITHER THE LIGHT SNOW OR SNOW SHOWERS GOING THRU LATE
MONDAY. SNOW ACCUMS LOOK TO BE AROUND AN ADDITIONAL INCH FOR MOST
AREAS...BUT OVER THE COURSE OF ANOTHER 12HRS OR SO. DEPENDING ON
HOW THIS ALL WORKS OUT...THE NATURE OF SHSN MAY SEE LOCALIZED HIGHER
AMOUNTS POSSIBLE. THE PERSISTENT LO CLOUDS SHOULD HANG IN TOUGH
THRU MONDAY AND WITH NW LO LEVEL WINDS AND LOTS OF FRESH SNOW
PACK...WHAT INSOLATION DOES MAKE IT THRU WILL GET MOSTLY BOUNCED
BACK...AND SO LOOK FOR MINIMAL TEMP RISES THIS DAY AS WELL...AND MOS
SEEMS TO HIGH ONCE AGAIN. UNDERCUT THE COLDER MET MOS NUMBERS BY A
COUPLE DEGS.
PERSISTENT CYCLONIC FLOW AND CLOUDS CONTINUE INTO MONDAY NIGHT AND
HAVE KEPT MENTION OF FLURRIES.
(TUESDAY - SATURDAY)
NW UPPER LEVEL FLOW WILL THEN CONTINUE FOR THE REMAINDER OF THE WEEK
CONTINUING THE BELOW AVERAGE TEMP REGIME AND ROUNDING OUT OUR RATHER
COLD MARCH. AN INVERTED TROF FOR THURSDAY AND THEN A CDFNT FOR
FRIDAY LOOK TO GIVE US SOME PCPN CHCS BY LATE IN THE WEEK...BUT
UNLIKE THE START OF THE WEEK...THESE PCPN CHCS SHOULD BE IN THE FORM
OF LIQUID.
TES
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1213 PM CDT SUN MAR 24 2013
DEFORMATION BAND OF SNOW WILL CONTINUE TO INTENSIFY THIS AFTERNOON
ALONG THE I-70 CORRIDOR AS THE UPPER LEVEL SYSTEM BEGINS TO PIVOT.
EVENTUALLY HEAVIEST SNOW WILL BEGIN TO WORK ITS WAY EAST...BY THIS
EVENING. IFR CONDITIONS TO CONTINUE WITH NORTH TO NORTHWEST WIND.
GRADUAL IMPROVEMENT OF CONDITIONS ANTICIPATED FROM WEST TO EAST
LATE TONIGHT AND TOMORROW MORNING...ALTHOUGH LIGHT SNOW AND
FLURRIES WILL PROBABLY CONTINUE AS UPPER LEVEL TROF REMAINS OVERHEAD.
SPECIFICS FOR KSTL...
IFR CONDITIONS WILL CONTINUE WITH PERIODS OF HEAVY SNOW THROUGH
THIS AFTERNOON. DEFORMATION BAND WILL SLOWLY MOVE EAST OF THE AREA
THIS EVENING WITH SNOW TAPERING OFF...VISIBILITY IMPROVING. LIGHT
SNOW AND FLURRIES ANTICIPATED TO REMAIN ACROSS THE AREA THROUGH
MONDAY MORNING THOUGH AS UPPER LEVEL TROF AXIS REMAINS OVER THE
AREA. NORTH WIND WILL BECOME NORTHWEST AND GUSTY THIS AFTERNOON AS
SURFACE LOW PULLS EAST OF THE AREA.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CRAWFORD
MO-IRON MO-MADISON MO-REYNOLDS MO-ST. FRANCOIS MO-STE.
GENEVIEVE MO-WASHINGTON MO.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR JEFFERSON MO-
LINCOLN MO-PIKE MO-ST. CHARLES MO-ST. LOUIS CITY MO-ST.
LOUIS MO.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR AUDRAIN MO-
BOONE MO-CALLAWAY MO-COLE MO-FRANKLIN MO-GASCONADE MO-KNOX
MO-LEWIS MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-
OSAGE MO-RALLS MO-SHELBY MO-WARREN MO.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR RANDOLPH
IL.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR ADAMS IL-
BOND IL-BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-
JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1036 AM CDT SUN MAR 24 2013
...MAJOR WINTER STORM WITH HEAVY SNOW IMPACTING THE AREA...
.UPDATE...
ISSUED AT 1030 AM CDT SUN MAR 24 2013
FORECAST LOOKS TO BE ON TRACK WITH MAJOR WINTER STORM IMPACTING
THE AREA TODAY INTO THIS EVENING. SOME PARTS OF CENTRAL MISSOURI
ARE ALREADY REPORTING 7+ INCHES OF SNOW ON THE GROUND...WITH MANY
REPORTS OF HEAVY SNOW AND THUNDERSNOW ALL ALONG THE I-70 CORRIDOR
IN MISSOURI. THERE HAVE ALSO BEEN MORE REPORTS OF SLEET THAN
EARLIER ANTICIPATED IN THE WARM ADVECTION PRECIP STILL ONGOING
ACROSS PARTS OF SOUTHWEST/SOUTH CENTRAL ILLINOIS. HAVE UPDATED THE
FORECAST TO ADD IN SOME SLEET IN THESE AREAS...AND A SMALL PART OF
SOUTHEAST MISSOURI. OTHERWISE...LITTLE CHANGE TO THE GOING
FORECAST AT THIS TIME.
CARNEY
&&
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 336 AM CDT SUN MAR 24 2013
PRIMARY FCST ISSUE FOR TODAY IS THE ONGOING WINTER STORM. WAA PCPN
WHICH DVLPD ACROSS THE AREA LAST NIGHT BRIEFLY CHANGED OVER TO A
RAIN/SNOW MIX AND EVEN SWITCHED OVER TO PURE SNOW IN SOME
LOCATIONS BEFORE ENDING. THERE WILL BE A BRIEF BREAK EARLY THIS
MORNING BETWEEN THE DEPARTING WAA PCPN AND THE HEAVIER SNOW
ASSOCIATED WITH THE DEFORMATION ZONE WHICH HAS ALREADY DVLPD IN
ERN KS AND WRN MO. MODELS ARE IN GENERALLY GOOD AGREEMENT THIS
MORNING WITH THE TRACK OF THE LOW PRESSURE SYSTEM...ESPECIALLY THE
ECMWF WHICH HAS BEEN FAIRLY CONSISTENT WITH THE TRACK OF THE H85
LOW ALTHOUGH THE 24/00Z RUN IS SOMEWHAT SLOWER THAN THE 23/00Z RUN
BETWEEN 12Z AND 18Z. THE TRACK OF THE H85 CIRCULATION CENTER FROM
NEAR KSGF/KUMN TO NEAR KFAM/KMDH IS VERY FAVORABLE FOR HEAVY SNOW
ACROSS THE CENTRAL PART OF THE CWA BASED ON LOCAL CLIMATOLOGY
PLOTS.
THERE ARE TWO ASPECTS OF THIS EVENT THAT REALLY CAUGHT MY
ATTENTION. FIRST...BUFKIT CROSS SECTIONS FROM A COUPLE OF MODELS
/INCLUDING THE RAP AND SREF/ SHOW VERY STRONG LIFT FOCUSED THROUGH
A RESPECTABLY DEEP DENDRITIC GROWTH ZONE WHICH IS OCCASIONALLY
SUPERSATURATED WITH RESPECT TO ICE. THIS IS ESPECIALLY TRUE
BETWEEN 15Z AND 00Z. SECOND...NO MATTER HOW YOU SLICE THE
ATMOSPHERE...THERE ARE INDICATIONS OF MODEST INSTABILITY /AT LEAST
FOR A WINTER EVENT/ ACROSS PARTS OF MO/IL TODAY. FCSTS OF H7-H5
LAPSE RATES EXCEED 7 DEG C/KM ACROSS THE SRN HALF OF THE CWA ON
THE RAP/WRF/SREF/NAM/GFS/UKMET AND EVEN THE ECMWF FCST EXCEEDS 6.5
DEG C/KM. BUFKIT SOUNDINGS ALSO SHOW UP TO 50 J/KG OF ELEVATED
CAPE AT TIMES. TAKEN TOGETHER...THESE TWO ITEMS SUGGEST THAT THERE
WILL BE PERIODS OF EFFICIENT SNOWFALL PRODUCTION WITHIN THE
DEFORMATION ZONE ALONG WITH OCCASIONAL CONVECTIVE ELEMENTS WHICH
WILL LOCALLY ENHANCE SNOWFALL RATES. IN TERMS OF SNOWFALL
AMOUNTS...IT STILL LOOKS LIKE A SOLID 6-8 INCHES OF SNOW ACROSS
THE WINTER STORM WARNING AREA WITH HIGHER AMOUNTS POSSIBLE.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 24 2013
(TONIGHT - MONDAY NIGHT)
MODELS HAVE ALL COME INTO A HARMONIOUS CONFLUENCE OF SOLUTIONS WITH
THE 00Z RUNS...WITH THE AGREED UPON TRACK MOST SIMILAR TO THE ECMWF
24HRS AGO...WITH THE GFS/NAM MORE SLY...AND THE GEM MORE NLY...AND
PLACES THIS STORM IN ABOUT THE MOST PERFECT SPOT TO MAXIMIZE SNOW
TOTALS ACROSS THE I-70 CORRIDOR WITH AN ELONGATED H850 LO TRACKING
THRU SRN MO AND SRN IL. ANOTHER TREND...THIS ONE TEMPORAL...HAS
BEEN TO SLOW DOWN THE EWD TRANSLATION OF THE STORM BY ABOUT 6HRS...
MEANING THE DEF ZONE PCPN FROM IT WILL LINGER WELL INTO THIS EVENING
FOR THE IL COUNTIES AND AREAS JUST W OF THE MS RIVER AND PERHAPS
EARLY OVERNIGHT FOR PARTS OF SWRN-SRN IL. SNOWFALL TOTALS HAVE BEEN
BUMPED UP AS A RESULT OF THE SLOWER EXIT...WITH AN ADDITIONAL 2-3"
FOR MUCH OF THE IL COUNTIES AND AROUND AN INCH MORE FOR THE REST.
HAVE EXPANDED THE REACH OF THE WARNING BACK TO THE W A BIT MORE. BY
THE TIME IT IS ALL SAID AND DONE...THE PALM SUNDAY SNOWSTORM OF 2013
IS EXPECTED TO BE ONE OF THOSE ONCE-IN-A-GENERATION TYPE STORMS FOR
OCCURRING SO LATE IN THE YEAR AND BEING SO POTENT.
THIS POTENT STORM SYSTEM WILL BE EXITING JUST AS ANOTHER...WEAKER...
SYSTEM MOVES IN. THIS SYSTEM IS THE OLD MONTANA LO THAT IS EXPECTED
TO OPEN UP LATER TODAY AND GET SUCKED IN THE UNDERTOW OF TODAY AND
THIS EVENING/S STORM SYSTEM...BECOMING SHEARED BY THE TIME IT
REACHES OUR AREA LATER TONIGHT AND CONTINUING INTO MONDAY...BUT WITH
ENOUGH TO KEEP EITHER THE LIGHT SNOW OR SNOW SHOWERS GOING THRU LATE
MONDAY. SNOW ACCUMS LOOK TO BE AROUND AN ADDITIONAL INCH FOR MOST
AREAS...BUT OVER THE COURSE OF ANOTHER 12HRS OR SO. DEPENDING ON
HOW THIS ALL WORKS OUT...THE NATURE OF SHSN MAY SEE LOCALIZED HIGHER
AMOUNTS POSSIBLE. THE PERSISTENT LO CLOUDS SHOULD HANG IN TOUGH
THRU MONDAY AND WITH NW LO LEVEL WINDS AND LOTS OF FRESH SNOW
PACK...WHAT INSOLATION DOES MAKE IT THRU WILL GET MOSTLY BOUNCED
BACK...AND SO LOOK FOR MINIMAL TEMP RISES THIS DAY AS WELL...AND MOS
SEEMS TO HIGH ONCE AGAIN. UNDERCUT THE COLDER MET MOS NUMBERS BY A
COUPLE DEGS.
PERSISTENT CYCLONIC FLOW AND CLOUDS CONTINUE INTO MONDAY NIGHT AND
HAVE KEPT MENTION OF FLURRIES.
(TUESDAY - SATURDAY)
NW UPPER LEVEL FLOW WILL THEN CONTINUE FOR THE REMAINDER OF THE WEEK
CONTINUING THE BELOW AVERAGE TEMP REGIME AND ROUNDING OUT OUR RATHER
COLD MARCH. AN INVERTED TROF FOR THURSDAY AND THEN A CDFNT FOR
FRIDAY LOOK TO GIVE US SOME PCPN CHCS BY LATE IN THE WEEK...BUT
UNLIKE THE START OF THE WEEK...THESE PCPN CHCS SHOULD BE IN THE FORM
OF LIQUID.
TES
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 834 AM CDT SUN MAR 24 2013
SNOW...HEAVY AT TIMES...WILL CONTINUE AS THE DEFORMATION ZONE
PIVOTS OVER THE REGION TODAY AND TONIGHT. IFR CONDITIONS EXPECTED
THROUGH THE PERIOD.
UPDATE...SEVERAL LIGHTNING STRIKES NOTED IN THE INITIAL BAND HAS
RESULTED IN REPORTS OF THUNDERSNOW AND SNOWFALL RATES APPROACHING
3 INCHES PER HOUR. HAVE UPDATED TAFS TO INCLUDE THESE CONDITIONS
AT KCOU...AND METRO STL TERMINALS.
SPECIFICS FOR KSTL...
EXPECT VERY HEAVY SNOWFALL TODAY WITH CONDITIONS DROPPING AT OR
BELOW AIRPORT MINIMUMS. CONDITIONS TO SLOWLY IMPROVE...BUT REMAIN
IFR THIS EVENING AS DEFORMATION BAND OF SNOW PIVOTS AND SLOWLY
MOVES EAST.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CRAWFORD
MO-IRON MO-MADISON MO-REYNOLDS MO-ST. FRANCOIS MO-STE.
GENEVIEVE MO-WASHINGTON MO.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR JEFFERSON MO-
LINCOLN MO-PIKE MO-ST. CHARLES MO-ST. LOUIS CITY MO-ST.
LOUIS MO.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR AUDRAIN MO-
BOONE MO-CALLAWAY MO-COLE MO-FRANKLIN MO-GASCONADE MO-KNOX
MO-LEWIS MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-
OSAGE MO-RALLS MO-SHELBY MO-WARREN MO.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR RANDOLPH
IL.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR ADAMS IL-
BOND IL-BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-
JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
843 AM CDT SUN MAR 24 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 336 AM CDT SUN MAR 24 2013
PRIMARY FCST ISSUE FOR TODAY IS THE ONGOING WINTER STORM. WAA PCPN
WHICH DVLPD ACROSS THE AREA LAST NIGHT BRIEFLY CHANGED OVER TO A
RAIN/SNOW MIX AND EVEN SWITCHED OVER TO PURE SNOW IN SOME
LOCATIONS BEFORE ENDING. THERE WILL BE A BRIEF BREAK EARLY THIS
MORNING BETWEEN THE DEPARTING WAA PCPN AND THE HEAVIER SNOW
ASSOCIATED WITH THE DEFORMATION ZONE WHICH HAS ALREADY DVLPD IN
ERN KS AND WRN MO. MODELS ARE IN GENERALLY GOOD AGREEMENT THIS
MORNING WITH THE TRACK OF THE LOW PRESSURE SYSTEM...ESPECIALLY THE
ECMWF WHICH HAS BEEN FAIRLY CONSISTENT WITH THE TRACK OF THE H85
LOW ALTHOUGH THE 24/00Z RUN IS SOMEWHAT SLOWER THAN THE 23/00Z RUN
BETWEEN 12Z AND 18Z. THE TRACK OF THE H85 CIRCULATION CENTER FROM
NEAR KSGF/KUMN TO NEAR KFAM/KMDH IS VERY FAVORABLE FOR HEAVY SNOW
ACROSS THE CENTRAL PART OF THE CWA BASED ON LOCAL CLIMATOLOGY
PLOTS.
THERE ARE TWO ASPECTS OF THIS EVENT THAT REALLY CAUGHT MY
ATTENTION. FIRST...BUFKIT CROSS SECTIONS FROM A COUPLE OF MODELS
/INCLUDING THE RAP AND SREF/ SHOW VERY STRONG LIFT FOCUSED THROUGH
A RESPECTABLY DEEP DENDRITIC GROWTH ZONE WHICH IS OCCASIONALLY
SUPERSATURATED WITH RESPECT TO ICE. THIS IS ESPECIALLY TRUE
BETWEEN 15Z AND 00Z. SECOND...NO MATTER HOW YOU SLICE THE
ATMOSPHERE...THERE ARE INDICATIONS OF MODEST INSTABILITY /AT LEAST
FOR A WINTER EVENT/ ACROSS PARTS OF MO/IL TODAY. FCSTS OF H7-H5
LAPSE RATES EXCEED 7 DEG C/KM ACROSS THE SRN HALF OF THE CWA ON
THE RAP/WRF/SREF/NAM/GFS/UKMET AND EVEN THE ECMWF FCST EXCEEDS 6.5
DEG C/KM. BUFKIT SOUNDINGS ALSO SHOW UP TO 50 J/KG OF ELEVATED
CAPE AT TIMES. TAKEN TOGETHER...THESE TWO ITEMS SUGGEST THAT THERE
WILL BE PERIODS OF EFFICIENT SNOWFALL PRODUCTION WITHIN THE
DEFORMATION ZONE ALONG WITH OCCASIONAL CONVECTIVE ELEMENTS WHICH
WILL LOCALLY ENHANCE SNOWFALL RATES. IN TERMS OF SNOWFALL
AMOUNTS...IT STILL LOOKS LIKE A SOLID 6-8 INCHES OF SNOW ACROSS
THE WINTER STORM WARNING AREA WITH HIGHER AMOUNTS POSSIBLE.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 24 2013
(TONIGHT - MONDAY NIGHT)
MODELS HAVE ALL COME INTO A HARMONIOUS CONFLUENCE OF SOLUTIONS WITH
THE 00Z RUNS...WITH THE AGREED UPON TRACK MOST SIMILAR TO THE ECMWF
24HRS AGO...WITH THE GFS/NAM MORE SLY...AND THE GEM MORE NLY...AND
PLACES THIS STORM IN ABOUT THE MOST PERFECT SPOT TO MAXIMIZE SNOW
TOTALS ACROSS THE I-70 CORRIDOR WITH AN ELONGATED H850 LO TRACKING
THRU SRN MO AND SRN IL. ANOTHER TREND...THIS ONE TEMPORAL...HAS
BEEN TO SLOW DOWN THE EWD TRANSLATION OF THE STORM BY ABOUT 6HRS...
MEANING THE DEF ZONE PCPN FROM IT WILL LINGER WELL INTO THIS EVENING
FOR THE IL COUNTIES AND AREAS JUST W OF THE MS RIVER AND PERHAPS
EARLY OVERNIGHT FOR PARTS OF SWRN-SRN IL. SNOWFALL TOTALS HAVE BEEN
BUMPED UP AS A RESULT OF THE SLOWER EXIT...WITH AN ADDITIONAL 2-3"
FOR MUCH OF THE IL COUNTIES AND AROUND AN INCH MORE FOR THE REST.
HAVE EXPANDED THE REACH OF THE WARNING BACK TO THE W A BIT MORE. BY
THE TIME IT IS ALL SAID AND DONE...THE PALM SUNDAY SNOWSTORM OF 2013
IS EXPECTED TO BE ONE OF THOSE ONCE-IN-A-GENERATION TYPE STORMS FOR
OCCURRING SO LATE IN THE YEAR AND BEING SO POTENT.
THIS POTENT STORM SYSTEM WILL BE EXITING JUST AS ANOTHER...WEAKER...
SYSTEM MOVES IN. THIS SYSTEM IS THE OLD MONTANA LO THAT IS EXPECTED
TO OPEN UP LATER TODAY AND GET SUCKED IN THE UNDERTOW OF TODAY AND
THIS EVENING/S STORM SYSTEM...BECOMING SHEARED BY THE TIME IT
REACHES OUR AREA LATER TONIGHT AND CONTINUING INTO MONDAY...BUT WITH
ENOUGH TO KEEP EITHER THE LIGHT SNOW OR SNOW SHOWERS GOING THRU LATE
MONDAY. SNOW ACCUMS LOOK TO BE AROUND AN ADDITIONAL INCH FOR MOST
AREAS...BUT OVER THE COURSE OF ANOTHER 12HRS OR SO. DEPENDING ON
HOW THIS ALL WORKS OUT...THE NATURE OF SHSN MAY SEE LOCALIZED HIGHER
AMOUNTS POSSIBLE. THE PERSISTENT LO CLOUDS SHOULD HANG IN TOUGH
THRU MONDAY AND WITH NW LO LEVEL WINDS AND LOTS OF FRESH SNOW
PACK...WHAT INSOLATION DOES MAKE IT THRU WILL GET MOSTLY BOUNCED
BACK...AND SO LOOK FOR MINIMAL TEMP RISES THIS DAY AS WELL...AND MOS
SEEMS TO HIGH ONCE AGAIN. UNDERCUT THE COLDER MET MOS NUMBERS BY A
COUPLE DEGS.
PERSISTENT CYCLONIC FLOW AND CLOUDS CONTINUE INTO MONDAY NIGHT AND
HAVE KEPT MENTION OF FLURRIES.
(TUESDAY - SATURDAY)
NW UPPER LEVEL FLOW WILL THEN CONTINUE FOR THE REMAINDER OF THE WEEK
CONTINUING THE BELOW AVERAGE TEMP REGIME AND ROUNDING OUT OUR RATHER
COLD MARCH. AN INVERTED TROF FOR THURSDAY AND THEN A CDFNT FOR
FRIDAY LOOK TO GIVE US SOME PCPN CHCS BY LATE IN THE WEEK...BUT
UNLIKE THE START OF THE WEEK...THESE PCPN CHCS SHOULD BE IN THE FORM
OF LIQUID.
TES
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 834 AM CDT SUN MAR 24 2013
SNOW...HEAVY AT TIMES...WILL CONTINUE AS THE DEFORMATION ZONE
PIVOTS OVER THE REGION TODAY AND TONIGHT. IFR CONDITIONS EXPECTED
THROUGH THE PERIOD.
UPDATE...SEVERAL LIGHTNING STRIKES NOTED IN THE INITIAL BAND HAS
RESULTED IN REPORTS OF THUNDERSNOW AND SNOWFALL RATES APPROACHING
3 INCHES PER HOUR. HAVE UPDATED TAFS TO INCLUDE THESE CONDITIONS
AT KCOU...AND METRO STL TERMINALS.
SPECIFICS FOR KSTL...
EXPECT VERY HEAVY SNOWFALL TODAY WITH CONDITIONS DROPPING AT OR
BELOW AIRPORT MINIMUMS. CONDITIONS TO SLOWLY IMPROVE...BUT REMAIN
IFR THIS EVENING AS DEFORMATION BAND OF SNOW PIVOTS AND SLOWLY
MOVES EAST.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CRAWFORD
MO-IRON MO-MADISON MO-REYNOLDS MO-ST. FRANCOIS MO-STE.
GENEVIEVE MO-WASHINGTON MO.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR JEFFERSON MO-
LINCOLN MO-PIKE MO-ST. CHARLES MO-ST. LOUIS CITY MO-ST.
LOUIS MO.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR AUDRAIN MO-
BOONE MO-CALLAWAY MO-COLE MO-FRANKLIN MO-GASCONADE MO-KNOX
MO-LEWIS MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-
OSAGE MO-RALLS MO-SHELBY MO-WARREN MO.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR RANDOLPH
IL.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR ADAMS IL-
BOND IL-BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-
JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
646 AM CDT SUN MAR 24 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 336 AM CDT SUN MAR 24 2013
PRIMARY FCST ISSUE FOR TODAY IS THE ONGOING WINTER STORM. WAA PCPN
WHICH DVLPD ACROSS THE AREA LAST NIGHT BRIEFLY CHANGED OVER TO A
RAIN/SNOW MIX AND EVEN SWITCHED OVER TO PURE SNOW IN SOME
LOCATIONS BEFORE ENDING. THERE WILL BE A BRIEF BREAK EARLY THIS
MORNING BETWEEN THE DEPARTING WAA PCPN AND THE HEAVIER SNOW
ASSOCIATED WITH THE DEFORMATION ZONE WHICH HAS ALREADY DVLPD IN
ERN KS AND WRN MO. MODELS ARE IN GENERALLY GOOD AGREEMENT THIS
MORNING WITH THE TRACK OF THE LOW PRESSURE SYSTEM...ESPECIALLY THE
ECMWF WHICH HAS BEEN FAIRLY CONSISTENT WITH THE TRACK OF THE H85
LOW ALTHOUGH THE 24/00Z RUN IS SOMEWHAT SLOWER THAN THE 23/00Z RUN
BETWEEN 12Z AND 18Z. THE TRACK OF THE H85 CIRCULATION CENTER FROM
NEAR KSGF/KUMN TO NEAR KFAM/KMDH IS VERY FAVORABLE FOR HEAVY SNOW
ACROSS THE CENTRAL PART OF THE CWA BASED ON LOCAL CLIMATOLOGY
PLOTS.
THERE ARE TWO ASPECTS OF THIS EVENT THAT REALLY CAUGHT MY
ATTENTION. FIRST...BUFKIT CROSS SECTIONS FROM A COUPLE OF MODELS
/INCLUDING THE RAP AND SREF/ SHOW VERY STRONG LIFT FOCUSED THROUGH
A RESPECTABLY DEEP DENDRITIC GROWTH ZONE WHICH IS OCCASIONALLY
SUPERSATURATED WITH RESPECT TO ICE. THIS IS ESPECIALLY TRUE
BETWEEN 15Z AND 00Z. SECOND...NO MATTER HOW YOU SLICE THE
ATMOSPHERE...THERE ARE INDICATIONS OF MODEST INSTABILITY /AT LEAST
FOR A WINTER EVENT/ ACROSS PARTS OF MO/IL TODAY. FCSTS OF H7-H5
LAPSE RATES EXCEED 7 DEG C/KM ACROSS THE SRN HALF OF THE CWA ON
THE RAP/WRF/SREF/NAM/GFS/UKMET AND EVEN THE ECMWF FCST EXCEEDS 6.5
DEG C/KM. BUFKIT SOUNDINGS ALSO SHOW UP TO 50 J/KG OF ELEVATED
CAPE AT TIMES. TAKEN TOGETHER...THESE TWO ITEMS SUGGEST THAT THERE
WILL BE PERIODS OF EFFICIENT SNOWFALL PRODUCTION WITHIN THE
DEFORMATION ZONE ALONG WITH OCCASIONAL CONVECTIVE ELEMENTS WHICH
WILL LOCALLY ENHANCE SNOWFALL RATES. IN TERMS OF SNOWFALL
AMOUNTS...IT STILL LOOKS LIKE A SOLID 6-8 INCHES OF SNOW ACROSS
THE WINTER STORM WARNING AREA WITH HIGHER AMOUNTS POSSIBLE.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 24 2013
(TONIGHT - MONDAY NIGHT)
MODELS HAVE ALL COME INTO A HARMONIOUS CONFLUENCE OF SOLUTIONS WITH
THE 00Z RUNS...WITH THE AGREED UPON TRACK MOST SIMILAR TO THE ECMWF
24HRS AGO...WITH THE GFS/NAM MORE SLY...AND THE GEM MORE NLY...AND
PLACES THIS STORM IN ABOUT THE MOST PERFECT SPOT TO MAXIMIZE SNOW
TOTALS ACROSS THE I-70 CORRIDOR WITH AN ELONGATED H850 LO TRACKING
THRU SRN MO AND SRN IL. ANOTHER TREND...THIS ONE TEMPORAL...HAS
BEEN TO SLOW DOWN THE EWD TRANSLATION OF THE STORM BY ABOUT 6HRS...
MEANING THE DEF ZONE PCPN FROM IT WILL LINGER WELL INTO THIS EVENING
FOR THE IL COUNTIES AND AREAS JUST W OF THE MS RIVER AND PERHAPS
EARLY OVERNIGHT FOR PARTS OF SWRN-SRN IL. SNOWFALL TOTALS HAVE BEEN
BUMPED UP AS A RESULT OF THE SLOWER EXIT...WITH AN ADDITIONAL 2-3"
FOR MUCH OF THE IL COUNTIES AND AROUND AN INCH MORE FOR THE REST.
HAVE EXPANDED THE REACH OF THE WARNING BACK TO THE W A BIT MORE. BY
THE TIME IT IS ALL SAID AND DONE...THE PALM SUNDAY SNOWSTORM OF 2013
IS EXPECTED TO BE ONE OF THOSE ONCE-IN-A-GENERATION TYPE STORMS FOR
OCCURRING SO LATE IN THE YEAR AND BEING SO POTENT.
THIS POTENT STORM SYSTEM WILL BE EXITING JUST AS ANOTHER...WEAKER...
SYSTEM MOVES IN. THIS SYSTEM IS THE OLD MONTANA LO THAT IS EXPECTED
TO OPEN UP LATER TODAY AND GET SUCKED IN THE UNDERTOW OF TODAY AND
THIS EVENING/S STORM SYSTEM...BECOMING SHEARED BY THE TIME IT
REACHES OUR AREA LATER TONIGHT AND CONTINUING INTO MONDAY...BUT WITH
ENOUGH TO KEEP EITHER THE LIGHT SNOW OR SNOW SHOWERS GOING THRU LATE
MONDAY. SNOW ACCUMS LOOK TO BE AROUND AN ADDITIONAL INCH FOR MOST
AREAS...BUT OVER THE COURSE OF ANOTHER 12HRS OR SO. DEPENDING ON
HOW THIS ALL WORKS OUT...THE NATURE OF SHSN MAY SEE LOCALIZED HIGHER
AMOUNTS POSSIBLE. THE PERSISTENT LO CLOUDS SHOULD HANG IN TOUGH
THRU MONDAY AND WITH NW LO LEVEL WINDS AND LOTS OF FRESH SNOW
PACK...WHAT INSOLATION DOES MAKE IT THRU WILL GET MOSTLY BOUNCED
BACK...AND SO LOOK FOR MINIMAL TEMP RISES THIS DAY AS WELL...AND MOS
SEEMS TO HIGH ONCE AGAIN. UNDERCUT THE COLDER MET MOS NUMBERS BY A
COUPLE DEGS.
PERSISTENT CYCLONIC FLOW AND CLOUDS CONTINUE INTO MONDAY NIGHT AND
HAVE KEPT MENTION OF FLURRIES.
(TUESDAY - SATURDAY)
NW UPPER LEVEL FLOW WILL THEN CONTINUE FOR THE REMAINDER OF THE WEEK
CONTINUING THE BELOW AVERAGE TEMP REGIME AND ROUNDING OUT OUR RATHER
COLD MARCH. AN INVERTED TROF FOR THURSDAY AND THEN A CDFNT FOR
FRIDAY LOOK TO GIVE US SOME PCPN CHCS BY LATE IN THE WEEK...BUT
UNLIKE THE START OF THE WEEK...THESE PCPN CHCS SHOULD BE IN THE FORM
OF LIQUID.
TES
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 629 AM CDT SUN MAR 24 2013
A LATE SEASON WINTER STORM WILL BRING SEVERAL HOURS OF HEAVY SNOW
TO THE TERMINALS TODAY...PRIMARILY BETWEEN 15Z AND 21Z. VSBYS MAY
FALL BELOW ONE-QUARTER MILE AT TIMES. SNOW INTENSITY WILL DECREASE
TONIGHT HOWEVER SNOWFALL WILL CONTINUE TO ACCUMULATE. TOTAL
ACCUMULATIONS OF 6-10 INCHES ARE EXPECTED WITH LOCALLY HIGHER
AMOUNTS POSSIBLE. BUFKIT SOUNDINGS SHOW THAT IFR CIGS WILL
PROBABLY PERSIST THROUGH MOST OF THE TAF PD ALTHOUGH THERE MAY BE
BRIEF WINDOWS WHERE CIGS RISE TO MVFR. ISOLATED THUNDERSTORMS HAVE
ALSO BEEN OCCURRING ALONG AND SOUTH OF INTERSTATE 70. AIRPORT
STAFF SHOULD EXPECT RAPIDLY ACCUMULATING SNOWFALL IF AREAS OF
THUNDERSNOW MOVE DIRECTLY OVER A TAF SITE. SUSTAINED WIND SPEEDS
WILL APPROACH 20 KTS WITH GUSTS TO NEAR 30 KTS AT TIMES TODAY
BEFORE WIND SPEEDS DECREASE LATE TONIGHT.
SPECIFICS FOR KSTL...A PD OF HEAVY SNOW IS EXPECTED TO LAST FOR
SEVERAL HOURS AT KSTL TODAY. VSBYS MAY FALL BELOW ONE-QUARTER MILE
AT TIMES. SNOW INTENSITY WILL DECREASE TONIGHT HOWEVER SNOWFALL
WILL CONTINUE TO ACCUMULATE. TOTAL ACCUMULATIONS OF 6-10 INCHES
ARE EXPECTED WITH LOCALLY HIGHER AMOUNTS POSSIBLE. BUFKIT
SOUNDINGS SHOW THAT IFR CIGS WILL PROBABLY PERSIST THROUGH MOST OF
THE TAF PD ALTHOUGH THERE MAY BE BRIEF WINDOWS WHERE CIGS RISE TO
MVFR. ISOLATED THUNDERSTORMS HAVE ALSO BEEN OCCURRING WITH THIS
STORM SYSTEM...THEREFORE AIRPORT STAFF SHOULD EXPECT RAPIDLY
ACCUMULATING SNOWFALL IF AREAS OF THUNDERSNOW MOVE DIRECTLY OVER
KSTL. SUSTAINED WIND SPEEDS WILL APPROACH 20 KTS WITH GUSTS TO
NEAR 30 KTS AT TIMES TODAY BEFORE WIND SPEEDS DECREASE LATE
TONIGHT.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CRAWFORD
MO-IRON MO-MADISON MO-REYNOLDS MO-ST. FRANCOIS MO-STE.
GENEVIEVE MO-WASHINGTON MO.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR JEFFERSON MO-
LINCOLN MO-PIKE MO-ST. CHARLES MO-ST. LOUIS CITY MO-ST.
LOUIS MO.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR AUDRAIN MO-
BOONE MO-CALLAWAY MO-COLE MO-FRANKLIN MO-GASCONADE MO-KNOX
MO-LEWIS MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-
OSAGE MO-RALLS MO-SHELBY MO-WARREN MO.
IL...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR RANDOLPH
IL.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR ADAMS IL-
BOND IL-BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-
JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
436 AM CDT SUN MAR 24 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 336 AM CDT SUN MAR 24 2013
PRIMARY FCST ISSUE FOR TODAY IS THE ONGOING WINTER STORM. WAA PCPN
WHICH DVLPD ACROSS THE AREA LAST NIGHT BRIEFLY CHANGED OVER TO A
RAIN/SNOW MIX AND EVEN SWITCHED OVER TO PURE SNOW IN SOME
LOCATIONS BEFORE ENDING. THERE WILL BE A BRIEF BREAK EARLY THIS
MORNING BETWEEN THE DEPARTING WAA PCPN AND THE HEAVIER SNOW
ASSOCIATED WITH THE DEFORMATION ZONE WHICH HAS ALREADY DVLPD IN
ERN KS AND WRN MO. MODELS ARE IN GENERALLY GOOD AGREEMENT THIS
MORNING WITH THE TRACK OF THE LOW PRESSURE SYSTEM...ESPECIALLY THE
ECMWF WHICH HAS BEEN FAIRLY CONSISTENT WITH THE TRACK OF THE H85
LOW ALTHOUGH THE 24/00Z RUN IS SOMEWHAT SLOWER THAN THE 23/00Z RUN
BETWEEN 12Z AND 18Z. THE TRACK OF THE H85 CIRCULATION CENTER FROM
NEAR KSGF/KUMN TO NEAR KFAM/KMDH IS VERY FAVORABLE FOR HEAVY SNOW
ACROSS THE CENTRAL PART OF THE CWA BASED ON LOCAL CLIMATOLOGY
PLOTS.
THERE ARE TWO ASPECTS OF THIS EVENT THAT REALLY CAUGHT MY
ATTENTION. FIRST...BUFKIT CROSS SECTIONS FROM A COUPLE OF MODELS
/INCLUDING THE RAP AND SREF/ SHOW VERY STRONG LIFT FOCUSED THROUGH
A RESPECTABLY DEEP DENDRITIC GROWTH ZONE WHICH IS OCCASIONALLY
SUPERSATURATED WITH RESPECT TO ICE. THIS IS ESPECIALLY TRUE
BETWEEN 15Z AND 00Z. SECOND...NO MATTER HOW YOU SLICE THE
ATMOSPHERE...THERE ARE INDICATIONS OF MODEST INSTABILITY /AT LEAST
FOR A WINTER EVENT/ ACROSS PARTS OF MO/IL TODAY. FCSTS OF H7-H5
LAPSE RATES EXCEED 7 DEG C/KM ACROSS THE SRN HALF OF THE CWA ON
THE RAP/WRF/SREF/NAM/GFS/UKMET AND EVEN THE ECMWF FCST EXCEEDS 6.5
DEG C/KM. BUFKIT SOUNDINGS ALSO SHOW UP TO 50 J/KG OF ELEVATED
CAPE AT TIMES. TAKEN TOGETHER...THESE TWO ITEMS SUGGEST THAT THERE
WILL BE PERIODS OF EFFICIENT SNOWFALL PRODUCTION WITHIN THE
DEFORMATION ZONE ALONG WITH OCCASIONAL CONVECTIVE ELEMENTS WHICH
WILL LOCALLY ENHANCE SNOWFALL RATES. IN TERMS OF SNOWFALL
AMOUNTS...IT STILL LOOKS LIKE A SOLID 6-8 INCHES OF SNOW ACROSS
THE WINTER STORM WARNING AREA WITH HIGHER AMOUNTS POSSIBLE.
KANOFSKY
&&
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 335 AM CDT SUN MAR 24 2013
(TONIGHT - MONDAY NIGHT)
MODELS HAVE ALL COME INTO A HARMONIOUS CONFLUENCE OF SOLUTIONS WITH
THE 00Z RUNS...WITH THE AGREED UPON TRACK MOST SIMILAR TO THE ECMWF
24HRS AGO...WITH THE GFS/NAM MORE SLY...AND THE GEM MORE NLY...AND
PLACES THIS STORM IN ABOUT THE MOST PERFECT SPOT TO MAXIMIZE SNOW
TOTALS ACROSS THE I-70 CORRIDOR WITH AN ELONGATED H850 LO TRACKING
THRU SRN MO AND SRN IL. ANOTHER TREND...THIS ONE TEMPORAL...HAS
BEEN TO SLOW DOWN THE EWD TRANSLATION OF THE STORM BY ABOUT 6HRS...
MEANING THE DEF ZONE PCPN FROM IT WILL LINGER WELL INTO THIS EVENING
FOR THE IL COUNTIES AND AREAS JUST W OF THE MS RIVER AND PERHAPS
EARLY OVERNIGHT FOR PARTS OF SWRN-SRN IL. SNOWFALL TOTALS HAVE BEEN
BUMPED UP AS A RESULT OF THE SLOWER EXIT...WITH AN ADDITIONAL 2-3"
FOR MUCH OF THE IL COUNTIES AND AROUND AN INCH MORE FOR THE REST.
HAVE EXPANDED THE REACH OF THE WARNING BACK TO THE W A BIT MORE. BY
THE TIME IT IS ALL SAID AND DONE...THE PALM SUNDAY SNOWSTORM OF 2013
IS EXPECTED TO BE ONE OF THOSE ONCE-IN-A-GENERATION TYPE STORMS FOR
OCCURRING SO LATE IN THE YEAR AND BEING SO POTENT.
THIS POTENT STORM SYSTEM WILL BE EXITING JUST AS ANOTHER...WEAKER...
SYSTEM MOVES IN. THIS SYSTEM IS THE OLD MONTANA LO THAT IS EXPECTED
TO OPEN UP LATER TODAY AND GET SUCKED IN THE UNDERTOW OF TODAY AND
THIS EVENING/S STORM SYSTEM...BECOMING SHEARED BY THE TIME IT
REACHES OUR AREA LATER TONIGHT AND CONTINUING INTO MONDAY...BUT WITH
ENOUGH TO KEEP EITHER THE LIGHT SNOW OR SNOW SHOWERS GOING THRU LATE
MONDAY. SNOW ACCUMS LOOK TO BE AROUND AN ADDITIONAL INCH FOR MOST
AREAS...BUT OVER THE COURSE OF ANOTHER 12HRS OR SO. DEPENDING ON
HOW THIS ALL WORKS OUT...THE NATURE OF SHSN MAY SEE LOCALIZED HIGHER
AMOUNTS POSSIBLE. THE PERSISTENT LO CLOUDS SHOULD HANG IN TOUGH
THRU MONDAY AND WITH NW LO LEVEL WINDS AND LOTS OF FRESH SNOW
PACK...WHAT INSOLATION DOES MAKE IT THRU WILL GET MOSTLY BOUNCED
BACK...AND SO LOOK FOR MINIMAL TEMP RISES THIS DAY AS WELL...AND MOS
SEEMS TO HIGH ONCE AGAIN. UNDERCUT THE COLDER MET MOS NUMBERS BY A
COUPLE DEGS.
PERSISTENT CYCLONIC FLOW AND CLOUDS CONTINUE INTO MONDAY NIGHT AND
HAVE KEPT MENTION OF FLURRIES.
(TUESDAY - SATURDAY)
NW UPPER LEVEL FLOW WILL THEN CONTINUE FOR THE REMAINDER OF THE WEEK
CONTINUING THE BELOW AVERAGE TEMP REGIME AND ROUNDING OUT OUR RATHER
COLD MARCH. AN INVERTED TROF FOR THURSDAY AND THEN A CDFNT FOR
FRIDAY LOOK TO GIVE US SOME PCPN CHCS BY LATE IN THE WEEK...BUT
UNLIKE THE START OF THE WEEK...THESE PCPN CHCS SHOULD BE IN THE FORM
OF LIQUID.
TES
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1043 PM CDT SAT MAR 23 2013
SCATTERED SHOWERS AND AREAS OF RAIN CONTINUE TO MOVE THROUGH THE
TAF SITES THIS EVENING AHEAD OF AN APPROACHING UPPER LEVEL
DISTURBANCE IN THE PLAINS. THE CLOUD CEILINGS WILL GRADUALLY LOWER
INTO THE MVFR CATEGORY BY 06Z SUN AS THE LOW LEVELS OF THE
ATMOSPHERE SATURATE. AS COLDER AIR FILTERS SEWD INTO THE REGION
LATE TGT THE RAIN WILL CHANGE OVER TO SNOW IN UIN AND COU AROUND
06-07Z SUN AND IN THE ST LOUIS METRO AREA AROUND 08-10Z SUN WITH
CEILINGS AND VSBYS LOWERING INTO THE IFR OR LIFR CATEGORY. THERE
MAY BE A BRIEF LULL IN THE SNOW EARLY SUN MRNG...BUT THEN THE SNOW
SHOULD BECOME HEAVY LATE SUN MRNG AND EARLY SUN AFTN AS THE
DEEPENING UPPER LEVEL AND ASSOCIATED SFC LOW PASS S-SE OF THE TAF
SITES. THE SNOW SHOULD TAPER OFF FROM W TO E LATE SUN AFTN AND
SUN EVNG AS THE STORM SYSTEM BEGINS TO PULL E-SE OF OUR AREA WITH
GRADUALLY IMPROVING VSBYS. E-NELY SFC WINDS WILL GRADUALLY BACK AROUND
TO A NLY DIRECTION SUN MRNG...AND THEN TO A NWLY DIRECTION SUN
AFTN. THE SFC WIND SPEEDS WILL INCREASE LATE TGT AND SUN MRNG
ALONG WITH BECOMING GUSTY AS THE SFC LOW DEVELOPS AND DEEPENS SE
OF THE TAF SITES.
SPECIFICS FOR KSTL...PERIODS OF RAIN WILL CONTINUE WITH A
GRADUALLY LOWERING CLOUD CEILING INTO THE MVFR CATEGORY BY 06Z
SUN. THE RAIN WILL CHANGE OVER TO SNOW BETWEEN 08-10Z SUN WITH
CIGS AND VSBYS LOWERING INTO THE IFR OR EVEN LIFR CATEGORY. THERE
MAY BE A BRIEF LULL IN THE PRECIPITATION AROUND 12Z SUN...BUT THEN
RAMP UP LATE SUN MRNG AND CONTINUING EARLY SUN AFTN WITH HEAVY
SNOW AT TIMES. THE SNOW SHOULD GRADUALLY TAPER OFF LATE SUN AFTN
AND THROUGH SUN NGT WITH SLOWLY IMPROVING CEILINGS AND VSBYS. NELY
SFC WIND WILL INCREASE THROUGH THE LATE NGT HOURS AND ON SUN
ALONG WITH BECOMING GUSTY. THE NELY SFC WIND WILL BACK AROUND TO A
NLY DIRECTION SUN MRNG AND A NWLY DIRECTION SUN AFTN. RELATIVELY
STRONG AND GUSTY NWLY SFC WINDS WILL CONTINUE SUN NGT WITH BLOWING
SNOW POSSIBLY REDUCING VSBYS.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM CDT THIS
EVENING FOR CRAWFORD MO-IRON MO-MADISON MO-REYNOLDS MO-ST.
FRANCOIS MO-STE. GENEVIEVE MO-WASHINGTON MO.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR JEFFERSON MO-
LINCOLN MO-PIKE MO-ST. CHARLES MO-ST. LOUIS CITY MO-ST.
LOUIS MO.
WINTER STORM WARNING UNTIL 7 PM CDT THIS EVENING FOR AUDRAIN MO-
BOONE MO-CALLAWAY MO-COLE MO-FRANKLIN MO-GASCONADE MO-KNOX
MO-LEWIS MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-
OSAGE MO-RALLS MO-SHELBY MO-WARREN MO.
IL...WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM CDT THIS
EVENING FOR RANDOLPH IL.
WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR ADAMS IL-
BOND IL-BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-
JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-
MONTGOMERY IL-PIKE IL-ST. CLAIR IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS BILLINGS MT
759 PM MDT MON MAR 25 2013
.SHORT TERM...VALID FOR TUE AND WED...
ONLY MINOR CHANGES WERE MADE TO THE OVERNIGHT FORECAST. IT WILL BE
RELATIVELY QUIET...EVEN AS A MODEST SHORT WAVE TROUGH AND BATCH OF
500-300 HPA Q-VECTOR FORCING MOVES INTO SOUTH CENTRAL MT IN THE 06
TO 12 UTC TIME FRAME. WE HAVE SOME POPS IN THE MOUNTAINS THANKS TO
THAT WAVE...BUT A VERY DRY LOWER-ELEVATION AIR MASS SHOULD PREVENT
ANY SHOWERS OUTSIDE OF THE HIGH COUNTRY. TEMPERATURES IN THAT VERY
DRY AIR MASS ARE THE MAIN CHALLENGE OVERNIGHT. RADIATIONAL COOLING
POTENTIAL IS LARGE WITH THE DRY AIR AND RELATIVELY WEAK BACKGROUND
FLOW. HOWEVER...UNLIKE LAST NIGHT...WE WILL NOT HAVE ENHANCED LOW-
LEVEL SUBSIDENCE BENEATH A SURFACE RIDGE...SO GUIDANCE SHOULD DO A
BETTER JOB OF MODELING LOWS. ON THAT NOTE...THE 18 UTC MULTI-MODEL
CONSENSUS SUPPORTED ACTUALLY RAISING LOWS SOME IN SOUTH CENTRAL MT
WHERE FLOW AND CLOUDS WILL BOTH INCREASE WITH THE APPROACH OF THAT
SHORT WAVE. NOTE THAT THE LAST FEW RAP RUNS SUGGEST OVERNIGHT LOWS
COULD BE SEVERAL DEGREES F WARMER THAN ADVERTISED IN SPOTS SUCH AS
BILLINGS. GIVEN THE DRY AIR...WE DID NOT LEAN ON THAT IDEA THOUGH.
OTHERWISE...WE LEFT PATCHY FOG IN THE FORECAST AFTER 06 UTC ACROSS
SOUTHEASTERN MT. WE SERIOUSLY CONSIDERED REMOVING ITS MENTION FROM
MILES CITY /LEAVING IT ONLY FOR BAKER AND EKALAKA/ BECAUSE NEITHER
MOS- OR BUFKIT-BASED OUTPUT SUPPORTS ITS FORMATION THERE. WE NOTED
SOME SNOWMELT SOUTHEAST OF MILES CITY ON VISIBLE SATELLITE IMAGERY
THIS AFTERNOON THOUGH...AND SOUTHEAST FLOW WOULD TAKE ANY MOISTURE
INTO MILES CITY...SO WE LEFT IT IN THE FORECAST THERE TOO. SCHULTZ
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
NO CHANGES TO THE EXTENDED FORECAST WITH A VERY QUIET WEATHER
PATTERN EVOLVING. MODELS REMAIN IN PRETTY GOOD AGREEMENT INTO THE
WEEKEND. RIDGING ON THURSDAY BEGINS TO BREAK DOWN FRIDAY WITH
CYCLONIC FLOW DEVELOPING ALOFT. A SHEARED VORTICITY REGION BUCKLES
INTO THE AREA FROM CANADA BRINGING A WEAK COLD FRONT INTO THE
AREA. THIS SHOULD BE ENOUGH FOR AT LEAST A FEW AREAS OF
PRECIPITATION FRIDAY INTO SATURDAY ACROSS THE LOWER ELEVATIONS.
BLOCKING PATTERN FORMS TO THE WEST OF THE AREA SUNDAY INTO MONDAY
WHICH SHOULD KEEP SYSTEMS TO THE NORTH AND SOUTH OF THE
AREA...WITH TEMPERATURES HOLDING NEAR TO ABOVE AVERAGE. CHAMBERS
&&
.AVIATION...
VFR CONDITIONS EXPECTED MOST AREAS TONIGHT. CLOUDS AND A FEW HIGH
ELEVATION SNOW SHOWERS WILL MOVE INTO THE WESTERN MOUNTAINS
BEFORE 12 UTC WITH OCCASIONAL MOUNTAIN OBSCURATION THROUGH TUESDAY
MORNING. PATCHY FOG IS POSSIBLE EAST OF A MILES CITY TO BROADUS
LINE IN THE EARLY MORNING HOURS WITH IFR OR LOWER CONDITIONS
POSSIBLE...ESPECIALLY AT BAKER. SCHULTZ/CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
TUE WED THU FRI SAT SUN MON
-----------------------------------------------------------
BIL 022/050 027/055 031/058 032/059 035/055 032/059 034/060
00/B 00/B 01/B 11/B 23/W 10/B 01/B
LVM 022/047 025/053 029/056 030/059 032/054 032/058 031/057
11/B 11/B 12/W 22/W 23/W 11/B 11/B
HDN 019/051 024/056 029/060 031/062 034/055 030/059 032/061
00/B 00/U 00/B 11/B 23/W 10/B 00/B
MLS 014/047 021/053 026/058 030/057 032/051 028/054 030/058
00/U 00/U 00/B 11/B 12/W 11/B 10/B
4BQ 012/047 021/053 027/057 030/059 032/053 028/056 030/059
00/U 00/U 00/B 01/B 13/W 11/B 10/B
BHK 009/040 016/045 019/049 024/049 027/045 024/048 026/051
00/U 00/U 00/B 11/B 12/W 11/B 11/B
SHR 012/045 022/050 028/055 029/055 031/052 029/055 031/057
00/B 00/U 00/B 11/B 23/W 11/B 10/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
619 PM CDT MON MAR 25 2013
.AVIATION...00Z TAFS FOR KOMA...KLNK AND KOFK. TRICKY FORECAST
TONIGHT AS MOST MODELS ALLOW CLOUDS TO SCATTER OUT THROUGH THE
NIGHT...BUT RAP KEEPS CLOUDS IN MUCH LONGER. WILL HOLD ONTO VFR
CLOUDS THROUGH ABOUT 06-08Z AS WEAK CYCLONIC FLOW REMAINS...BUT
THEN WILL FOLLOW MOST MODELS AND SCATTER THINGS OUT BEYOND THEN.
COULD THEN SEE SOME PATCHY MVFR FOG OVERNIGHT. NORTHWEST WINDS
INITIALLY AT 12 TO 15 KNOTS THROUGH ABOUT 01Z...THEN WINDS
DIMINISHING SIGNIFICANTLY TO LESS THAN 8 KNOTS...AND EVENTUALLY
BECOMING LIGHT AND VARIABLE OVERNIGHT.
&&
.PREV DISCUSSION... /ISSUED 256 PM CDT MON MAR 25 2013/
SHORT TERM...TONIGHT THROUGH TUESDAY.
PRIMARY FORECAST CONCERN IS CLOUD COVER...WHICH WILL HAVE A BIG
AFFECT ON TEMPERATURES.
TROUGH AT 500 MB WILL CONTINUE TO MOVE SOUTHEAST AWAY FROM THE
REGION OVERNIGHT...WHILE A RIDGE OF HIGH PRESSURE AT THE SURFACE
BUILDS INTO THE AREA LATER TONIGHT. NORTHWEST WINDS SHOULD
DIMINISH TONIGHT AS THE PRESSURE GRADIENT WEAKENS. ALSO EXPECT
CLOUDS TO DECREASE...ESPECIALLY AFTER MIDNIGHT. MODELS ARE NOT IN
GOOD AGREEMENT IN REGARDS TO CLEARING OUT LOW CLOUDS...BUT OVERALL
TREND SHOULD BE FOR DRYING ABOVE 900 MB. SOME PATCHY FOG APPEARS
POSSIBLE AFTER THE CLOUDS MOVE OUT AND WINDS DROP OFF. LOWS SHOULD
DROP INTO THE TEENS MOST AREAS.
ON TUESDAY...WINDS WILL GRADUALLY BECOME SOUTHERLY AS THE HIGH MOVES
INTO CENTRAL IOWA AND CENTRAL MISSOURI BY LATE AFTERNOON. EXPECT
HIGHS ONLY IN THE MID TO UPPER 30S...DUE TO SHALLOW MIXING. HIGH
LEVEL CLOUDINESS SHOULD INCREASE DURING THE AFTERNOON.
LONG TERM...TUESDAY NIGHT THROUGH MONDAY.
WARMING TREND STILL ON TAP FOR THE REGION DURING THIS TIME FRAME.
GENERALLY DRY CONDITIONS UNTIL AROUND SATURDAY WHEN ANOTHER COLD
FRONT IS EXPECTED TO MOVE THROUGH. MODELS VARY SOME ON TIMING WITH
EURO A BIT SLOWER THAN THE GFS SO ADJUSTMENTS ARE POSSIBLE IN
LATER FORECASTS. WARMER TEMPERATURES LOOK TO BE IN PLACE FOR THIS
FRONTAL PASSAGE SO RAIN MORE LIKELY THAN SNOW THIS TIME AROUND.
TEMPERATURES AT THE END OF THE PERIOD ON MONDAY MAY ALSO BE
PROBLEMATIC AS GFS IS CONSIDERABLY WARMER THAN THE EURO WHICH
PULLS DOWN A MUCH STRONGER AREA OF HIGH PRESSURE AND COLDER
TEMPERATURES.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION...CORRECTED
NWS HASTINGS NE
101 PM CDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 101 PM CDT SUN MAR 24 2013
TEMPS/DWPTS IN GOOD SHAPE. MADE SOME MINOR ADJUSTMENTS TO CLOUDS.
VIS SATL SHOWS WIDESPREAD STRATOCU DEVELOPING BETWEEN LBF-TIF AND
HEADING FOR LXN. LNX 88D AND A CALL FROM LBF INDICATES FLURRIES.
SO FLURRIES HAVE RETURNED TO THE FCST FOR THIS AFTN. STRATOCU ARE
STRUGGLING TO FORM OVER MUCH OF THE FCST AREA. SO HIGHEST
CONFIDENCE IS W OF HWY 183. FCST SKY COVER THIS AFTN MAY NEED TO BE
LOWERED E OF HWY 183.
UPDATE ISSUED AT 932 CDT SUN MAR 24 2013
CYCLOGENESIS IS UNDERWAY OVER THE MID MS VALLEY. A SHRTWV RIDGE IS
OVER THE FCST AREA IN ITS WAKE AND HAS RESULTED IN CLEARING. 12Z
SOUNDINGS SHOW EXTENSIVE MSTR ALL THE WAY BACK TO MT/ND. SO EXPECT
DIURNAL STRATOCU TO DEVELOP AROUND MIDDAY.
THE BACK EDGE OF THE CIRRUS CANOPY WITH THE MID MS VALLEY LOW WAS
EXITING OUR ERN COUNTIES ALONG HWY 81. THESE AREAS WILL BECOME SUNNY
BY 11 AM.
VIS SATELLITE ALSO SHOW SOME MID-HIGH CLOUDS OVER WY AND NRN CO.
THESE CLOUDS WILL ALSO DIVE SE INTO THE FCST AREA. SO OVERALL EXPECT
A SUNNY MRNG TO TURN P/CLOUDY THIS AFTN.
DID MAKE SOME SUBSTANTIAL ADJUSTMENTS TO SKY FCST FORENOON TO ACCT
FOR CLEARING. WILL CONT TO MONITOR TEMP CURVES.
IT/S COLD! THE CAMBRIDGE CO-OP OBSERVER HAD A LOW TEMP OF 9F. AN
NDOR MESONET SITE IN ARAPAHOE ALSO REPORTED 9F. WIND CHILLS ARE
MOSTLY IN THE SINGLE DIGITS ACROSS THE FCST AREA.
OVERALL A BLUSTERY COLD DAY. 06Z NAM/11Z RAP BUFKIT TIME SECTIONS
SUGGEST PEAK WINDS AVAILABLE FOR MIXING ARE 30-33 KTS. SO NW WINDS
WILL GUST 25-35 MPH...THO LESS FREQUENTLY IN THE 30-35 MPH RANGE.
OTHER THAN SHORT-TERM SKY ALL OTHER FCST ELEMENTS LOOK GOOD.
ANALOGS: LOOKING BACK AT THE FCST ANALOG YEARS FROM 10 DAYS AGO...
THEY HAD A GREAT SIGNAL FOR THIS CURRENT STRETCH OF UNSEASONABLY
COLD MARCH WX. THOSE INCLUDED 1951 52 57 58 62 AND 2006.
UPDATE ISSUED AT 543 AM CDT SUN MAR 24 2013
UPDATED THE FORECAST FOR TODAY TO MAKE MINOR ADJUSTMENTS TO HOURLY
TEMPERATURES...WINDS...AND DEWPOINTS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 509 AM CDT SUN MAR 24 2013
THE MAIN CHALLENGE WILL BE DETERMINING CHANCES FOR FLURRIES/SNOW
SHOWERS TODAY AND TONIGHT.
UPPER LEVEL JET STREAM HAS MADE A DIVE WELL SOUTH OF THE AREA WITH A
RATHER LARGE LONGWAVE TROUGH OVER THE CENTRAL UNITED STATES. THIS
SHOULD ENSURE THAT WE REMAIN WELL BELOW NORMAL TODAY. AT
MID-LEVELS...A SOMEWHAT COMPLEX SCENARIO IS TAKING PLACE. A SET OF
DUMBBELL CLOSED LOWS OCCUPY THE AFOREMENTIONED LONGWAVE
TROUGH...WITH ONE OF THE LOWS TRACKING TO THE EAST ACROSS
SOUTHEASTERN KANSAS. THE SECOND LOW IS LOCATED OVER NORTH DAKOTA.
FOR TODAY...WE SHOULD BE IN AN AREA BETWEEN THE TWO CLOSED
LOW...WITH SOME SHORTWAVE RIDGING. THIS SHOULD KEEP FLURRIES/SNOW
SHOWERS OUT OF THE AREA DURING THE DAY TODAY...AND PERHAPS ALLOW A
PEAK OR TWO AT SOME SUN. WITH 850 MB TEMPERATURES RATHER SIMILAR TO
SATURDAY...AND WITH THE BIT OF CHANCE AT A PEAK OR TWO OF LATE MARCH
SUN...I HAVE BUMPED UP TEMPERATURES A BIT FOR TODAY.
THE APPROACHING CLOSED LOW IS EXPECTED TO FILL TODAY AS IT HEADS
SOUTH. THE LEFTOVER LOBE OF ENERGY WILL ARRIVE THIS EVENING AND
COULD SPAWN MORE FLURRIES/SNOW SHOWERS...WITH BETTER CHANCES TO THE
EAST/NORTHEAST...WITH THE BEST LARGE SCALE TO THE EAST/NORTHEAST. I
WENT WITH SIMILAR LOW TEMPERATURES TONIGHT COMPARED TO THE PREVIOUS
FORECAST WITH ONLY MINOR ADJUSTMENTS. BUMPED UP WIND SPEEDS JUST A
BIT WITH INCREASING LOW-LEVEL LAPSE RATES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 509 AM CDT SUN MAR 24 2013
THIS 6-DAY PERIOD WILL BE HIGHLIGHTED BY WHAT CURRENTLY APPEARS TO
BE A FEW LOW-END CHANCES FOR GENERALLY LIGHT MEASURABLE PRECIP...BUT
MORE IMPORTANTLY TO MANY FOLKS...A LEGITIMATE WARMING TREND BACK
INTO THE 40S AND AT LEAST 50S.
CERTAINLY MONDAY THROUGH TUESDAY THE AREA WILL STILL BE MIRED IN THE
MUCH-BELOW NORMAL COLD AIR. STARTING OFF SUNRISE MONDAY
MORNING...00Z/06Z MODELS SUCH AS THE NAM/GFS/ECMWF ARE IN GOOD
AGREEMENT DEPICTING AN ELONGATED MID LEVEL TROUGH EXTENDING FROM
NORTHWEST-SOUTHEAST ACROSS THE CENTRAL PLAINS...WHICH THEN GRADUALLY
DEPARTS TO THE SOUTHEAST DURING THE DAY...FEEDING INTO THE ENTRANCE
REGION OF A STOUT UPPER LEVEL JET STREAK ACROSS THE SOUTHEAST CONUS.
AT THE SURFACE MONDAY...ALTHOUGH A GRADUAL DECREASE IN WIND SPEEDS
WILL OCCUR DURING THE DAY...THE COMBINATION OF DEEP MIXING AND A
STILL TIGHTENED PRESSURE GRADIENT WILL RESULT IN FAIRLY BREEZY
CONDITIONS WITH SUSTAINED NORTHWEST WINDS AT LEAST 20 MPH GUSTING
25-30 MPH. THESE WINDS WILL RESULT IN ANOTHER VERY COLD DAY FOR LATE
MARCH...WITH WIND CHILL READINGS DURING THE AFTERNOON STRUGGLING TO
REACH THE LOW 20S. ACTUAL AIR TEMPERATURES WILL BE VERY SIMILAR TO
THOSE OF TODAY...WITH LOW TO POSSIBLY MID 30S CWA-WIDE.
PRECIPITATION-WISE...AS NOTED BY THE PAST SEVERAL FORECAST
SHIFTS...THIS IS A FAIRLY CLASSIC SETUP FOR AT LEAST A SLIGHT CHANCE
OF FLURRIES...AS FORCING FROM THE OVERHEAD ELONGATED SHORTWAVE
COMBINES WITH FAVORABLE DENDRITIC TEMPERATURES AROUND -11C IN A LOW
STRATUS LAYER TO SQUEEZE OUT SOME FLAKES. AS NOTED BY PREVIOUS DAY
SHIFT...PARTS OF THE EASTERN CWA COULD EVEN SEE SOME VERY LIGHT
MEASURABLE SNOW OF MAYBE A TENTH OF AN INCH OR TWO...AS SUGGESTED BY
LIGHT QPF EVIDENT IN VARIOUS MODEL FIELDS. AS A RESULT...MAINTAINED
A FLURRY CHANCE IN THE WEST THROUGH THE DAY...BUT ACTUALLY BEEFED UP
ROUGHLY THE NORTHEAST 1/2 OF THE CWA TO A 20 TO 30 PERCENT CHANCE OF
MEASURABLE LIGHT SNOW. THIS SHOULDN/T BE ANY KIND OF IMPACTFUL
SNOW...BUT FELT IT WAS WORTHY OF A SMALL POP AS SOME AREAS COULD SEE
A BIT MORE THAN FLURRIES. BY SUNSET MONDAY NIGHT...THE
AFOREMENTIONED MID LEVEL WAVE WILL BE JUST DEPARTING THE SOUTHERN
END OF THE CWA...AND ALTHOUGH SOME DEGREE OF LOW STRATUS COULD
LINGER THROUGH THE NIGHT...FEEL THE RISK OF LINGERING FLURRIES/LIGHT
SNOW IS LOW ENOUGH BY THEN TO END THE MENTION. TEMP-WISE...ITS VERY
POSSIBLE THAT MONDAY NIGHT COULD IN FACT BE THE COLDEST NIGHT FOR
THE NEXT SEVERAL MONTHS...AS A SURFACE RIDGE AXIS SETTLES IN AND
BREEZES BECOME VERY LIGHT BY SUNRISE. ALTHOUGH LINGERING CLOUDS
COULD WORK AGAINST A MAJOR DROP-OFF...WILL STILL CALL FOR MOST OF
THE CWA SETTLING DOWN TO AT LEAST 14-18 DEGREES. DESPITE THE LIGHT
WINDS...AM NOT OVERLY CONCERNED ABOUT IMPACTFUL FOG DEVELOPMENT...SO
WILL CONTINUE TO OMIT FROM THE FORECAST.
TUESDAY/TUESDAY NIGHT...CONFIDENCE IS RATHER HIGH IN A PRECIP-FREE
24 HOURS...ALTHOUGH WILL ACKNOWLEDGE THAT THE ECMWF CONTINUES TO
SPIT OUT SOME VERY LIGHT QPF NEAR THE SOUTHWEST EDGE OF THE CWA LATE
TUES NIGHT...LIKELY IN RESPONSE TO A MODEST BELT OF LOW-MID LEVEL
THETA-E ADVECTION AS A VERY SUBTLE MID LEVEL SHORTWAVE TROUGH
RIPPLES THROUGH WEST-NORTHWEST FLOW ALOFT. THE THINKING FOR NOW IS
THAT FAIRLY DRY LOW LEVELS WILL WORK AGAINST PRECIP
DEVELOPING...ESPECIALLY OF THE MEASURABLE VARIETY. HOWEVER...IT WILL
BEAR WATCHING AS TEMPERATURE PROFILES WOULD SUGGEST A LOW-END RISK
OF LIGHT FREEZING RAIN IF SOMETHING WERE TO MOVE IN. FOR NOW WILL
LEAVE TUES NIGHT PRECIP FREE THOUGH. BACKING UP TO THE TUESDAY
DAYTIME HOURS...DEVELOPING SOUTHERLY BREEZES SHOULD MARK THE
BEGINNING STAGES OF A NICE WARM-UP...AND NUDGED UP HIGH TEMPS A BIT
GETTING NEARLY ALL AREAS INTO THE LOW OR MID 40S.
WEDNESDAY/WEDNESDAY NIGHT...HAVE MAINTAINED A DRY
FORECAST...ALTHOUGH ITS NOT NECESSARILY A GUARANTEE TO STAY THAT WAY
AS BOTH THE ECMWF/GFS CONTINUE TO BRING A SERIES OF WEAK SHORTWAVES
THROUGH THE PERSISTENT WEST-NORTHWEST FLOW...WHICH COULD SATURATE
THE MID LEVELS JUST ENOUGH TO PRODUCE SOME SPRINKLES OR LIGHT RAIN.
AGAIN...CONFIDENCE JUST ISN/T HIGH ENOUGH TO GO THERE YET.
TEMP-WISE...THE WARM-UP CONTINUES WITH ALL NEBRASKA ZONES AIMED WELL
INTO THE MID-UPPER 40S AND EVEN SOME 50S NEAR/SOUTH OF THE STATE
LINE.
THURSDAY/THURSDAY NIGHT...BROAD WEST-NORTHWEST FLOW JUST KEEPS ON
PERSISTING OVER THE CENTRAL PLAINS...WITH EVEN A HINT OF HEIGHT
RISES AS A RIDGE BUILDS EASTWARD A BIT FROM THE ROCKIES. ALTHOUGH
ODDS ARE REASONABLY HIGH THAT THIS 24 HOURS WILL REMAIN
DRY...ESPECIALLY THE DAYTIME...WILL CONTINUE TO HANG ONTO A SLIGHT
CHANCE OF RAIN THURSDAY NIGHT FROM THE PREVIOUS FORECAST...ALTHOUGH
THIS CHANCE MAY VERY WELL BE DROPPED IN THE COMING DAYS. CONTINUED
MODIFICATION OF THE LOW LEVEL TEMPERATURE FIELDS RAISES CONFIDENCE
IN WIDESPREAD 50S FOR THURSDAY...WHICH WOULD MARK THE FIRST TIME IN
9-13 DAYS THAT MOST OF THE CWA HAS CRACKED 50.
FRIDAY/FRIDAY NIGHT...THE CWA-WIDE SLIGHT CHANCES OF RAIN SHOWERS
WERE MAINTAINED FROM THE PREVIOUS FORECAST...BUT AGAIN ITS BY NO
MEANS LOOKING LIKE A WIDESPREAD MEASURABLE RAIN RISK. THAT BEING
SAID...GRADUAL MOISTENING OF THE LOW LEVELS EVIDENT AT 850 MILLIBARS
COULD ACTUALLY GENERATE SOME WEAK INSTABILITY BY THIS TIME...AND
THUS ITS NOT COMPLETELY OUT OF THE QUESTION THAT A FEW WEAK
THUNDERSTORMS COULD MATERIALIZE ON A HIT AN MISS BASIS. WILL HOLD
OFF ON ANY THUNDER MENTION FOR NOW STILL BEING 5+ DAYS OUT...BUT
SOMETHING TO KEEP AN EYE ON. FOR NOW...WILL KEEP HIGH TEMPS FRIDAY
SIMILAR TO THURS WITH MID-UPPER 50S...BUT THE MEX GUIDANCE WOULD
SUGGEST IT COULD BE A BIT WARMER THAN THIS.
FINALLY FOR SATURDAY DAYTIME...CHANCES FOR RAIN SHOWERS CURRENTLY
APPEAR A BIT BETTER THAN PREVIOUS DAYS...AND THUS WILL GO WITH SOME
30 POPS BUT STILL KEEPING CHANCES FAIRLY LOW AT THIS TIME RANGE.
ESPECIALLY THE ECMWF SUGGESTS THAT A MODEST SHORTWAVE TROUGH COULD
DROP IN FROM THE NORTHWEST...AND PUSH A WEAK COLD FRONT THROUGH THE
REGION...PROVIDING A BIT MORE FORCING. AGAIN WILL HOLD OFF ON THE
INTRODUCTION OF THUNDERSTORMS AND JUST GO WITH SHOWER WORDING...BUT
THIS WILL BEAR WATCHING AS WEAK INSTABILITY COULD CERTAINLY BE IN
PLACE BY THEN. WILL AIM HIGH TEMPS IN THE 50S AGAIN...BUT DEPENDING
ON HOW TRENDS PLAY OUT WOULD NOT BE SURPRISED TO SEE SOME AREAS
CRACK 60.
&&
.AVIATION...(FOR THE 18Z TAF THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1258 PM CDT SUN MAR 24 2013
THIS AFTN: VFR WITH NW WINDS GUSTING TO 30 KTS AT TIMES. SCT
STRATOCU WILL CONTINUE TO FORM AND COULD RESULT IN A VFR CIG AFTER
21Z.
TNGT: VFR CIGS PROBABLY DEGRADE TO MVFR WITH SCT FLURRIES.
CONFIDENCE IS BELOW AVERAGE AND MVFR MAY NOT PREVAIL MUCH OF THE
TIME. WHILE THERE ARE MVFR CIGS UPSTREAM...THEY DEVELOPED WITH
DAYTIME HEATING AND ARE EXPECTED TO PARTIALLY DISSIPATE AFTER
SUNSET. INDICATED SOME LOWERING OF NW WINDS AND AN END TO THE
GUSTINESS...BUT WINDS COULD BE HIGHER THAN FCST IF THE WINDIER MET
MOS ENDS UP CORRECT.
MON THRU 18Z: MVFR CIGS MAY CONTINUE WITH OCCASIONAL FLURRIES.
AFTER 15Z NW WINDS GUST TO 25 KTS.
CIG CONFIDENCE: HIGH THRU 02Z THEN LOW UNTIL 18Z
VSBY CONFIDENCE: HIGH THRU 02Z THEN AVERAGE. LOW PROB 4SM SHSN
WIND CONFIDENCE: HIGH THRU 02Z THEN AVERAGE TNGT
WX CONFIDENCE: HIGH
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...HEINLEIN
LONG TERM...PFANNKUCH
AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1258 PM CDT SUN MAR 24 2013
.UPDATE...
ISSUED AT 1258 PM CDT SUN MAR 24 2013
TEMPS/DWPTS IN GOOD SHAPE. MADE SOME MINOR ADJUSTMENTS TO CLOUDS.
VIS SATL SHOWS WIDESPREAD STRATOCU DEVELOPING BETWEEN LBF-TIF AND
HEADING FOR LXN. LNX 88D AND A CALL FROM LBF INDICATES FLURRIES.
SO FLURRIES HAVE RETURNED TO THE FCST FOR THIS AFTN. STRATOCU ARE
STRUGGLING TO FORM OVER MUCH OF THE FCST AREA. SO HIGHEST
CONFIDENCE IS W OF HWY 183. FCST SKY COVER THIS AFTER MAY NEED TO
BE LOWERED E OF HWY 183.
UPDATE ISSUED AT 932 CDT SUN MAR 24 2013
CYCLOGENESIS IS UNDERWAY OVER THE MID MS VALLEY. A SHRTWV RIDGE IS
OVER THE FCST AREA IN ITS WAKE AND HAS RESULTED IN CLEARING. 12Z
SOUNDINGS SHOW EXTENSIVE MSTR ALL THE WAY BACK TO MT/ND. SO EXPECT
DIURNAL STRATOCU TO DEVELOP AROUND MIDDAY.
THE BACK EDGE OF THE CIRRUS CANOPY WITH THE MID MS VALLEY LOW WAS
EXITING OUR ERN COUNTIES ALONG HWY 81. THESE AREAS WILL BECOME SUNNY
BY 11 AM.
VIS SATELLITE ALSO SHOW SOME MID-HIGH CLOUDS OVER WY AND NRN CO.
THESE CLOUDS WILL ALSO DIVE SE INTO THE FCST AREA. SO OVERALL EXPECT
A SUNNY MRNG TO TURN P/CLOUDY THIS AFTN.
DID MAKE SOME SUBSTANTIAL ADJUSTMENTS TO SKY FCST FORENOON TO ACCT
FOR CLEARING. WILL CONT TO MONITOR TEMP CURVES.
IT/S COLD! THE CAMBRIDGE CO-OP OBSERVER HAD A LOW TEMP OF 9F. AN
NDOR MESONET SITE IN ARAPAHOE ALSO REPORTED 9F. WIND CHILLS ARE
MOSTLY IN THE SINGLE DIGITS ACROSS THE FCST AREA.
OVERALL A BLUSTERY COLD DAY. 06Z NAM/11Z RAP BUFKIT TIME SECTIONS
SUGGEST PEAK WINDS AVAILABLE FOR MIXING ARE 30-33 KTS. SO NW WINDS
WILL GUST 25-35 MPH...THO LESS FREQUENTLY IN THE 30-35 MPH RANGE.
OTHER THAN SHORT-TERM SKY ALL OTHER FCST ELEMENTS LOOK GOOD.
ANALOGS: LOOKING BACK AT THE FCST ANALOG YEARS FROM 10 DAYS AGO...
THEY HAD A GREAT SIGNAL FOR THIS CURRENT STRETCH OF UNSEASONABLY
COLD MARCH WX. THOSE INCLUDED 1951 52 57 58 62 AND 2006.
UPDATE ISSUED AT 543 AM CDT SUN MAR 24 2013
UPDATED THE FORECAST FOR TODAY TO MAKE MINOR ADJUSTMENTS TO HOURLY
TEMPERATURES...WINDS...AND DEWPOINTS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 509 AM CDT SUN MAR 24 2013
THE MAIN CHALLENGE WILL BE DETERMINING CHANCES FOR FLURRIES/SNOW
SHOWERS TODAY AND TONIGHT.
UPPER LEVEL JET STREAM HAS MADE A DIVE WELL SOUTH OF THE AREA WITH A
RATHER LARGE LONGWAVE TROUGH OVER THE CENTRAL UNITED STATES. THIS
SHOULD ENSURE THAT WE REMAIN WELL BELOW NORMAL TODAY. AT
MID-LEVELS...A SOMEWHAT COMPLEX SCENARIO IS TAKING PLACE. A SET OF
DUMBBELL CLOSED LOWS OCCUPY THE AFOREMENTIONED LONGWAVE
TROUGH...WITH ONE OF THE LOWS TRACKING TO THE EAST ACROSS
SOUTHEASTERN KANSAS. THE SECOND LOW IS LOCATED OVER NORTH DAKOTA.
FOR TODAY...WE SHOULD BE IN AN AREA BETWEEN THE TWO CLOSED
LOW...WITH SOME SHORTWAVE RIDGING. THIS SHOULD KEEP FLURRIES/SNOW
SHOWERS OUT OF THE AREA DURING THE DAY TODAY...AND PERHAPS ALLOW A
PEAK OR TWO AT SOME SUN. WITH 850 MB TEMPERATURES RATHER SIMILAR TO
SATURDAY...AND WITH THE BIT OF CHANCE AT A PEAK OR TWO OF LATE MARCH
SUN...I HAVE BUMPED UP TEMPERATURES A BIT FOR TODAY.
THE APPROACHING CLOSED LOW IS EXPECTED TO FILL TODAY AS IT HEADS
SOUTH. THE LEFTOVER LOBE OF ENERGY WILL ARRIVE THIS EVENING AND
COULD SPAWN MORE FLURRIES/SNOW SHOWERS...WITH BETTER CHANCES TO THE
EAST/NORTHEAST...WITH THE BEST LARGE SCALE TO THE EAST/NORTHEAST. I
WENT WITH SIMILAR LOW TEMPERATURES TONIGHT COMPARED TO THE PREVIOUS
FORECAST WITH ONLY MINOR ADJUSTMENTS. BUMPED UP WIND SPEEDS JUST A
BIT WITH INCREASING LOW-LEVEL LAPSE RATES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 509 AM CDT SUN MAR 24 2013
THIS 6-DAY PERIOD WILL BE HIGHLIGHTED BY WHAT CURRENTLY APPEARS TO
BE A FEW LOW-END CHANCES FOR GENERALLY LIGHT MEASURABLE PRECIP...BUT
MORE IMPORTANTLY TO MANY FOLKS...A LEGITIMATE WARMING TREND BACK
INTO THE 40S AND AT LEAST 50S.
CERTAINLY MONDAY THROUGH TUESDAY THE AREA WILL STILL BE MIRED IN THE
MUCH-BELOW NORMAL COLD AIR. STARTING OFF SUNRISE MONDAY
MORNING...00Z/06Z MODELS SUCH AS THE NAM/GFS/ECMWF ARE IN GOOD
AGREEMENT DEPICTING AN ELONGATED MID LEVEL TROUGH EXTENDING FROM
NORTHWEST-SOUTHEAST ACROSS THE CENTRAL PLAINS...WHICH THEN GRADUALLY
DEPARTS TO THE SOUTHEAST DURING THE DAY...FEEDING INTO THE ENTRANCE
REGION OF A STOUT UPPER LEVEL JET STREAK ACROSS THE SOUTHEAST CONUS.
AT THE SURFACE MONDAY...ALTHOUGH A GRADUAL DECREASE IN WIND SPEEDS
WILL OCCUR DURING THE DAY...THE COMBINATION OF DEEP MIXING AND A
STILL TIGHTENED PRESSURE GRADIENT WILL RESULT IN FAIRLY BREEZY
CONDITIONS WITH SUSTAINED NORTHWEST WINDS AT LEAST 20 MPH GUSTING
25-30 MPH. THESE WINDS WILL RESULT IN ANOTHER VERY COLD DAY FOR LATE
MARCH...WITH WIND CHILL READINGS DURING THE AFTERNOON STRUGGLING TO
REACH THE LOW 20S. ACTUAL AIR TEMPERATURES WILL BE VERY SIMILAR TO
THOSE OF TODAY...WITH LOW TO POSSIBLY MID 30S CWA-WIDE.
PRECIPITATION-WISE...AS NOTED BY THE PAST SEVERAL FORECAST
SHIFTS...THIS IS A FAIRLY CLASSIC SETUP FOR AT LEAST A SLIGHT CHANCE
OF FLURRIES...AS FORCING FROM THE OVERHEAD ELONGATED SHORTWAVE
COMBINES WITH FAVORABLE DENDRITIC TEMPERATURES AROUND -11C IN A LOW
STRATUS LAYER TO SQUEEZE OUT SOME FLAKES. AS NOTED BY PREVIOUS DAY
SHIFT...PARTS OF THE EASTERN CWA COULD EVEN SEE SOME VERY LIGHT
MEASURABLE SNOW OF MAYBE A TENTH OF AN INCH OR TWO...AS SUGGESTED BY
LIGHT QPF EVIDENT IN VARIOUS MODEL FIELDS. AS A RESULT...MAINTAINED
A FLURRY CHANCE IN THE WEST THROUGH THE DAY...BUT ACTUALLY BEEFED UP
ROUGHLY THE NORTHEAST 1/2 OF THE CWA TO A 20 TO 30 PERCENT CHANCE OF
MEASURABLE LIGHT SNOW. THIS SHOULDN/T BE ANY KIND OF IMPACTFUL
SNOW...BUT FELT IT WAS WORTHY OF A SMALL POP AS SOME AREAS COULD SEE
A BIT MORE THAN FLURRIES. BY SUNSET MONDAY NIGHT...THE
AFOREMENTIONED MID LEVEL WAVE WILL BE JUST DEPARTING THE SOUTHERN
END OF THE CWA...AND ALTHOUGH SOME DEGREE OF LOW STRATUS COULD
LINGER THROUGH THE NIGHT...FEEL THE RISK OF LINGERING FLURRIES/LIGHT
SNOW IS LOW ENOUGH BY THEN TO END THE MENTION. TEMP-WISE...ITS VERY
POSSIBLE THAT MONDAY NIGHT COULD IN FACT BE THE COLDEST NIGHT FOR
THE NEXT SEVERAL MONTHS...AS A SURFACE RIDGE AXIS SETTLES IN AND
BREEZES BECOME VERY LIGHT BY SUNRISE. ALTHOUGH LINGERING CLOUDS
COULD WORK AGAINST A MAJOR DROP-OFF...WILL STILL CALL FOR MOST OF
THE CWA SETTLING DOWN TO AT LEAST 14-18 DEGREES. DESPITE THE LIGHT
WINDS...AM NOT OVERLY CONCERNED ABOUT IMPACTFUL FOG DEVELOPMENT...SO
WILL CONTINUE TO OMIT FROM THE FORECAST.
TUESDAY/TUESDAY NIGHT...CONFIDENCE IS RATHER HIGH IN A PRECIP-FREE
24 HOURS...ALTHOUGH WILL ACKNOWLEDGE THAT THE ECMWF CONTINUES TO
SPIT OUT SOME VERY LIGHT QPF NEAR THE SOUTHWEST EDGE OF THE CWA LATE
TUES NIGHT...LIKELY IN RESPONSE TO A MODEST BELT OF LOW-MID LEVEL
THETA-E ADVECTION AS A VERY SUBTLE MID LEVEL SHORTWAVE TROUGH
RIPPLES THROUGH WEST-NORTHWEST FLOW ALOFT. THE THINKING FOR NOW IS
THAT FAIRLY DRY LOW LEVELS WILL WORK AGAINST PRECIP
DEVELOPING...ESPECIALLY OF THE MEASURABLE VARIETY. HOWEVER...IT WILL
BEAR WATCHING AS TEMPERATURE PROFILES WOULD SUGGEST A LOW-END RISK
OF LIGHT FREEZING RAIN IF SOMETHING WERE TO MOVE IN. FOR NOW WILL
LEAVE TUES NIGHT PRECIP FREE THOUGH. BACKING UP TO THE TUESDAY
DAYTIME HOURS...DEVELOPING SOUTHERLY BREEZES SHOULD MARK THE
BEGINNING STAGES OF A NICE WARM-UP...AND NUDGED UP HIGH TEMPS A BIT
GETTING NEARLY ALL AREAS INTO THE LOW OR MID 40S.
WEDNESDAY/WEDNESDAY NIGHT...HAVE MAINTAINED A DRY
FORECAST...ALTHOUGH ITS NOT NECESSARILY A GUARANTEE TO STAY THAT WAY
AS BOTH THE ECMWF/GFS CONTINUE TO BRING A SERIES OF WEAK SHORTWAVES
THROUGH THE PERSISTENT WEST-NORTHWEST FLOW...WHICH COULD SATURATE
THE MID LEVELS JUST ENOUGH TO PRODUCE SOME SPRINKLES OR LIGHT RAIN.
AGAIN...CONFIDENCE JUST ISN/T HIGH ENOUGH TO GO THERE YET.
TEMP-WISE...THE WARM-UP CONTINUES WITH ALL NEBRASKA ZONES AIMED WELL
INTO THE MID-UPPER 40S AND EVEN SOME 50S NEAR/SOUTH OF THE STATE
LINE.
THURSDAY/THURSDAY NIGHT...BROAD WEST-NORTHWEST FLOW JUST KEEPS ON
PERSISTING OVER THE CENTRAL PLAINS...WITH EVEN A HINT OF HEIGHT
RISES AS A RIDGE BUILDS EASTWARD A BIT FROM THE ROCKIES. ALTHOUGH
ODDS ARE REASONABLY HIGH THAT THIS 24 HOURS WILL REMAIN
DRY...ESPECIALLY THE DAYTIME...WILL CONTINUE TO HANG ONTO A SLIGHT
CHANCE OF RAIN THURSDAY NIGHT FROM THE PREVIOUS FORECAST...ALTHOUGH
THIS CHANCE MAY VERY WELL BE DROPPED IN THE COMING DAYS. CONTINUED
MODIFICATION OF THE LOW LEVEL TEMPERATURE FIELDS RAISES CONFIDENCE
IN WIDESPREAD 50S FOR THURSDAY...WHICH WOULD MARK THE FIRST TIME IN
9-13 DAYS THAT MOST OF THE CWA HAS CRACKED 50.
FRIDAY/FRIDAY NIGHT...THE CWA-WIDE SLIGHT CHANCES OF RAIN SHOWERS
WERE MAINTAINED FROM THE PREVIOUS FORECAST...BUT AGAIN ITS BY NO
MEANS LOOKING LIKE A WIDESPREAD MEASURABLE RAIN RISK. THAT BEING
SAID...GRADUAL MOISTENING OF THE LOW LEVELS EVIDENT AT 850 MILLIBARS
COULD ACTUALLY GENERATE SOME WEAK INSTABILITY BY THIS TIME...AND
THUS ITS NOT COMPLETELY OUT OF THE QUESTION THAT A FEW WEAK
THUNDERSTORMS COULD MATERIALIZE ON A HIT AN MISS BASIS. WILL HOLD
OFF ON ANY THUNDER MENTION FOR NOW STILL BEING 5+ DAYS OUT...BUT
SOMETHING TO KEEP AN EYE ON. FOR NOW...WILL KEEP HIGH TEMPS FRIDAY
SIMILAR TO THURS WITH MID-UPPER 50S...BUT THE MEX GUIDANCE WOULD
SUGGEST IT COULD BE A BIT WARMER THAN THIS.
FINALLY FOR SATURDAY DAYTIME...CHANCES FOR RAIN SHOWERS CURRENTLY
APPEAR A BIT BETTER THAN PREVIOUS DAYS...AND THUS WILL GO WITH SOME
30 POPS BUT STILL KEEPING CHANCES FAIRLY LOW AT THIS TIME RANGE.
ESPECIALLY THE ECMWF SUGGESTS THAT A MODEST SHORTWAVE TROUGH COULD
DROP IN FROM THE NORTHWEST...AND PUSH A WEAK COLD FRONT THROUGH THE
REGION...PROVIDING A BIT MORE FORCING. AGAIN WILL HOLD OFF ON THE
INTRODUCTION OF THUNDERSTORMS AND JUST GO WITH SHOWER WORDING...BUT
THIS WILL BEAR WATCHING AS WEAK INSTABILITY COULD CERTAINLY BE IN
PLACE BY THEN. WILL AIM HIGH TEMPS IN THE 50S AGAIN...BUT DEPENDING
ON HOW TRENDS PLAY OUT WOULD NOT BE SURPRISED TO SEE SOME AREAS
CRACK 60.
&&
.AVIATION...(FOR THE 18Z TAF THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1258 PM CDT SUN MAR 24 2013
THIS AFTN: VFR WITH NW WINDS GUSTING TO 30 KTS AT TIMES. SCT
STRATOCU WILL CONTINUE TO FORM AND COULD RESULT IN A VFR CIG AFTER
21Z.
TNGT: VFR CIGS PROBABLY DEGRADE TO MVFR WITH SCT FLURRIES.
CONFIDENCE IS BELOW AVERAGE AND MVFR MAY NOT PREVAIL MUCH OF THE
TIME. WHILE THERE ARE MVFR CIGS UPSTREAM...THEY DEVELOPED WITH
DAYTIME HEATING AND ARE EXPECTED TO PARTIALLY DISSIPATE AFTER
SUNSET. INDICATED SOME LOWERING OF NW WINDS AND AN END TO THE
GUSTINESS...BUT WINDS COULD BE HIGHER THAN FCST IF THE WINDIER MET
MOS ENDS UP CORRECT.
MON THRU 18Z: MVFR CIGS MAY CONTINUE WITH OCCASIONAL FLURRIES.
AFTER 15Z NW WINDS GUST TO 25 KTS.
CIG CONFIDENCE: HIGH THRU 02Z THEN LOW UNTIL 18Z
VSBY CONFIDENCE: HIGH THRU 02Z THEN AVERAGE. LOW PROB 4SM SHSN
WIND CONFIDENCE: HIGH THRU 02Z THEN AVERAGE TNGT
WX CONFIDENCE: HIGH
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...HEINLEIN
LONG TERM...PFANNKUCH
AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
932 AM CDT SUN MAR 24 2013
...A COLD AND SUNNY START WITH WIND CHILLS PUSHING ZERO AT MID-
MRNG THEN NW WINDS INCREASE AND BECOME GUSTY AFTER 11 AM...
.UPDATE...
ISSUED AT 932 CDT SUN MAR 24 2013
CYCLOGENESIS IS UNDERWAY OVER THE MID MS VALLEY. A SHRTWV RIDGE IS
OVER THE FCST AREA IN ITS WAKE AND HAS RESULTED IN CLEARING. 12Z
SOUNDINGS SHOW EXTENSIVE MSTR ALL THE WAY BACK TO MT/ND. SO EXPECT
DIURNAL STRATOCU TO DEVELOP AROUND MIDDAY.
THE BACK EDGE OF THE CIRRUS CANOPY WITH THE MID MS VALLEY LOW WAS
EXITING OUR ERN COUNTIES ALONG HWY 81. THESE AREAS WILL BECOME SUNNY
BY 11 AM.
VIS SATELLITE ALSO SHOW SOME MID-HIGH CLOUDS OVER WY AND NRN CO.
THESE CLOUDS WILL ALSO DIVE SE INTO THE FCST AREA. SO OVERALL EXPECT
A SUNNY MRNG TO TURN P/CLOUDY THIS AFTN.
DID MAKE SOME SUBSTANTIAL ADJUSTMENTS TO SKY FCST FORENOON TO ACCT
FOR CLEARING. WILL CONT TO MONITOR TEMP CURVES.
IT/S COLD! THE CAMBRIDGE CO-OP OBSERVER HAD A LOW TEMP OF 9F. AN
NDOR MESONET SITE IN ARAPAHOE ALSO REPORTED 9F. WIND CHILLS ARE
MOSTLY IN THE SINGLE DIGITS ACROSS THE FCST AREA.
OVERALL A BLUSTERY COLD DAY. 06Z NAM/11Z RAP BUFKIT TIME SECTIONS
SUGGEST PEAK WINDS AVAILABLE FOR MIXING ARE 30-33 KTS. SO NW WINDS
WILL GUST 25-35 MPH...THO LESS FREQUENTLY IN THE 30-35 MPH RANGE.
OTHER THAN SHORT-TERM SKY ALL OTHER FCST ELEMENTS LOOK GOOD.
ANALOGS: LOOKING BACK AT THE FCST ANALOG YEARS FROM 10 DAYS AGO...
THEY HAD A GREAT SIGNAL FOR THIS CURRENT STRETCH OF UNSEASONABLY
COLD MARCH WX. THOSE INCLUDED 1951 52 57 58 62 AND 2006.
UPDATE ISSUED AT 543 AM CDT SUN MAR 24 2013
UPDATED THE FORECAST FOR TODAY TO MAKE MINOR ADJUSTMENTS TO HOURLY
TEMPERATURES...WINDS...AND DEWPOINTS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 509 AM CDT SUN MAR 24 2013
THE MAIN CHALLENGE WILL BE DETERMINING CHANCES FOR FLURRIES/SNOW
SHOWERS TODAY AND TONIGHT.
UPPER LEVEL JET STREAM HAS MADE A DIVE WELL SOUTH OF THE AREA WITH A
RATHER LARGE LONGWAVE TROUGH OVER THE CENTRAL UNITED STATES. THIS
SHOULD ENSURE THAT WE REMAIN WELL BELOW NORMAL TODAY. AT
MID-LEVELS...A SOMEWHAT COMPLEX SCENARIO IS TAKING PLACE. A SET OF
DUMBBELL CLOSED LOWS OCCUPY THE AFOREMENTIONED LONGWAVE
TROUGH...WITH ONE OF THE LOWS TRACKING TO THE EAST ACROSS
SOUTHEASTERN KANSAS. THE SECOND LOW IS LOCATED OVER NORTH DAKOTA.
FOR TODAY...WE SHOULD BE IN AN AREA BETWEEN THE TWO CLOSED
LOW...WITH SOME SHORTWAVE RIDGING. THIS SHOULD KEEP FLURRIES/SNOW
SHOWERS OUT OF THE AREA DURING THE DAY TODAY...AND PERHAPS ALLOW A
PEAK OR TWO AT SOME SUN. WITH 850 MB TEMPERATURES RATHER SIMILAR TO
SATURDAY...AND WITH THE BIT OF CHANCE AT A PEAK OR TWO OF LATE MARCH
SUN...I HAVE BUMPED UP TEMPERATURES A BIT FOR TODAY.
THE APPROACHING CLOSED LOW IS EXPECTED TO FILL TODAY AS IT HEADS
SOUTH. THE LEFTOVER LOBE OF ENERGY WILL ARRIVE THIS EVENING AND
COULD SPAWN MORE FLURRIES/SNOW SHOWERS...WITH BETTER CHANCES TO THE
EAST/NORTHEAST...WITH THE BEST LARGE SCALE TO THE EAST/NORTHEAST. I
WENT WITH SIMILAR LOW TEMPERATURES TONIGHT COMPARED TO THE PREVIOUS
FORECAST WITH ONLY MINOR ADJUSTMENTS. BUMPED UP WIND SPEEDS JUST A
BIT WITH INCREASING LOW-LEVEL LAPSE RATES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 509 AM CDT SUN MAR 24 2013
THIS 6-DAY PERIOD WILL BE HIGHLIGHTED BY WHAT CURRENTLY APPEARS TO
BE A FEW LOW-END CHANCES FOR GENERALLY LIGHT MEASURABLE PRECIP...BUT
MORE IMPORTANTLY TO MANY FOLKS...A LEGITIMATE WARMING TREND BACK
INTO THE 40S AND AT LEAST 50S.
CERTAINLY MONDAY THROUGH TUESDAY THE AREA WILL STILL BE MIRED IN THE
MUCH-BELOW NORMAL COLD AIR. STARTING OFF SUNRISE MONDAY
MORNING...00Z/06Z MODELS SUCH AS THE NAM/GFS/ECMWF ARE IN GOOD
AGREEMENT DEPICTING AN ELONGATED MID LEVEL TROUGH EXTENDING FROM
NORTHWEST-SOUTHEAST ACROSS THE CENTRAL PLAINS...WHICH THEN GRADUALLY
DEPARTS TO THE SOUTHEAST DURING THE DAY...FEEDING INTO THE ENTRANCE
REGION OF A STOUT UPPER LEVEL JET STREAK ACROSS THE SOUTHEAST CONUS.
AT THE SURFACE MONDAY...ALTHOUGH A GRADUAL DECREASE IN WIND SPEEDS
WILL OCCUR DURING THE DAY...THE COMBINATION OF DEEP MIXING AND A
STILL TIGHTENED PRESSURE GRADIENT WILL RESULT IN FAIRLY BREEZY
CONDITIONS WITH SUSTAINED NORTHWEST WINDS AT LEAST 20 MPH GUSTING
25-30 MPH. THESE WINDS WILL RESULT IN ANOTHER VERY COLD DAY FOR LATE
MARCH...WITH WIND CHILL READINGS DURING THE AFTERNOON STRUGGLING TO
REACH THE LOW 20S. ACTUAL AIR TEMPERATURES WILL BE VERY SIMILAR TO
THOSE OF TODAY...WITH LOW TO POSSIBLY MID 30S CWA-WIDE.
PRECIPITATION-WISE...AS NOTED BY THE PAST SEVERAL FORECAST
SHIFTS...THIS IS A FAIRLY CLASSIC SETUP FOR AT LEAST A SLIGHT CHANCE
OF FLURRIES...AS FORCING FROM THE OVERHEAD ELONGATED SHORTWAVE
COMBINES WITH FAVORABLE DENDRITIC TEMPERATURES AROUND -11C IN A LOW
STRATUS LAYER TO SQUEEZE OUT SOME FLAKES. AS NOTED BY PREVIOUS DAY
SHIFT...PARTS OF THE EASTERN CWA COULD EVEN SEE SOME VERY LIGHT
MEASURABLE SNOW OF MAYBE A TENTH OF AN INCH OR TWO...AS SUGGESTED BY
LIGHT QPF EVIDENT IN VARIOUS MODEL FIELDS. AS A RESULT...MAINTAINED
A FLURRY CHANCE IN THE WEST THROUGH THE DAY...BUT ACTUALLY BEEFED UP
ROUGHLY THE NORTHEAST 1/2 OF THE CWA TO A 20 TO 30 PERCENT CHANCE OF
MEASURABLE LIGHT SNOW. THIS SHOULDN/T BE ANY KIND OF IMPACTFUL
SNOW...BUT FELT IT WAS WORTHY OF A SMALL POP AS SOME AREAS COULD SEE
A BIT MORE THAN FLURRIES. BY SUNSET MONDAY NIGHT...THE
AFOREMENTIONED MID LEVEL WAVE WILL BE JUST DEPARTING THE SOUTHERN
END OF THE CWA...AND ALTHOUGH SOME DEGREE OF LOW STRATUS COULD
LINGER THROUGH THE NIGHT...FEEL THE RISK OF LINGERING FLURRIES/LIGHT
SNOW IS LOW ENOUGH BY THEN TO END THE MENTION. TEMP-WISE...ITS VERY
POSSIBLE THAT MONDAY NIGHT COULD IN FACT BE THE COLDEST NIGHT FOR
THE NEXT SEVERAL MONTHS...AS A SURFACE RIDGE AXIS SETTLES IN AND
BREEZES BECOME VERY LIGHT BY SUNRISE. ALTHOUGH LINGERING CLOUDS
COULD WORK AGAINST A MAJOR DROP-OFF...WILL STILL CALL FOR MOST OF
THE CWA SETTLING DOWN TO AT LEAST 14-18 DEGREES. DESPITE THE LIGHT
WINDS...AM NOT OVERLY CONCERNED ABOUT IMPACTFUL FOG DEVELOPMENT...SO
WILL CONTINUE TO OMIT FROM THE FORECAST.
TUESDAY/TUESDAY NIGHT...CONFIDENCE IS RATHER HIGH IN A PRECIP-FREE
24 HOURS...ALTHOUGH WILL ACKNOWLEDGE THAT THE ECMWF CONTINUES TO
SPIT OUT SOME VERY LIGHT QPF NEAR THE SOUTHWEST EDGE OF THE CWA LATE
TUES NIGHT...LIKELY IN RESPONSE TO A MODEST BELT OF LOW-MID LEVEL
THETA-E ADVECTION AS A VERY SUBTLE MID LEVEL SHORTWAVE TROUGH
RIPPLES THROUGH WEST-NORTHWEST FLOW ALOFT. THE THINKING FOR NOW IS
THAT FAIRLY DRY LOW LEVELS WILL WORK AGAINST PRECIP
DEVELOPING...ESPECIALLY OF THE MEASURABLE VARIETY. HOWEVER...IT WILL
BEAR WATCHING AS TEMPERATURE PROFILES WOULD SUGGEST A LOW-END RISK
OF LIGHT FREEZING RAIN IF SOMETHING WERE TO MOVE IN. FOR NOW WILL
LEAVE TUES NIGHT PRECIP FREE THOUGH. BACKING UP TO THE TUESDAY
DAYTIME HOURS...DEVELOPING SOUTHERLY BREEZES SHOULD MARK THE
BEGINNING STAGES OF A NICE WARM-UP...AND NUDGED UP HIGH TEMPS A BIT
GETTING NEARLY ALL AREAS INTO THE LOW OR MID 40S.
WEDNESDAY/WEDNESDAY NIGHT...HAVE MAINTAINED A DRY
FORECAST...ALTHOUGH ITS NOT NECESSARILY A GUARANTEE TO STAY THAT WAY
AS BOTH THE ECMWF/GFS CONTINUE TO BRING A SERIES OF WEAK SHORTWAVES
THROUGH THE PERSISTENT WEST-NORTHWEST FLOW...WHICH COULD SATURATE
THE MID LEVELS JUST ENOUGH TO PRODUCE SOME SPRINKLES OR LIGHT RAIN.
AGAIN...CONFIDENCE JUST ISN/T HIGH ENOUGH TO GO THERE YET.
TEMP-WISE...THE WARM-UP CONTINUES WITH ALL NEBRASKA ZONES AIMED WELL
INTO THE MID-UPPER 40S AND EVEN SOME 50S NEAR/SOUTH OF THE STATE
LINE.
THURSDAY/THURSDAY NIGHT...BROAD WEST-NORTHWEST FLOW JUST KEEPS ON
PERSISTING OVER THE CENTRAL PLAINS...WITH EVEN A HINT OF HEIGHT
RISES AS A RIDGE BUILDS EASTWARD A BIT FROM THE ROCKIES. ALTHOUGH
ODDS ARE REASONABLY HIGH THAT THIS 24 HOURS WILL REMAIN
DRY...ESPECIALLY THE DAYTIME...WILL CONTINUE TO HANG ONTO A SLIGHT
CHANCE OF RAIN THURSDAY NIGHT FROM THE PREVIOUS FORECAST...ALTHOUGH
THIS CHANCE MAY VERY WELL BE DROPPED IN THE COMING DAYS. CONTINUED
MODIFICATION OF THE LOW LEVEL TEMPERATURE FIELDS RAISES CONFIDENCE
IN WIDESPREAD 50S FOR THURSDAY...WHICH WOULD MARK THE FIRST TIME IN
9-13 DAYS THAT MOST OF THE CWA HAS CRACKED 50.
FRIDAY/FRIDAY NIGHT...THE CWA-WIDE SLIGHT CHANCES OF RAIN SHOWERS
WERE MAINTAINED FROM THE PREVIOUS FORECAST...BUT AGAIN ITS BY NO
MEANS LOOKING LIKE A WIDESPREAD MEASURABLE RAIN RISK. THAT BEING
SAID...GRADUAL MOISTENING OF THE LOW LEVELS EVIDENT AT 850 MILLIBARS
COULD ACTUALLY GENERATE SOME WEAK INSTABILITY BY THIS TIME...AND
THUS ITS NOT COMPLETELY OUT OF THE QUESTION THAT A FEW WEAK
THUNDERSTORMS COULD MATERIALIZE ON A HIT AN MISS BASIS. WILL HOLD
OFF ON ANY THUNDER MENTION FOR NOW STILL BEING 5+ DAYS OUT...BUT
SOMETHING TO KEEP AN EYE ON. FOR NOW...WILL KEEP HIGH TEMPS FRIDAY
SIMILAR TO THURS WITH MID-UPPER 50S...BUT THE MEX GUIDANCE WOULD
SUGGEST IT COULD BE A BIT WARMER THAN THIS.
FINALLY FOR SATURDAY DAYTIME...CHANCES FOR RAIN SHOWERS CURRENTLY
APPEAR A BIT BETTER THAN PREVIOUS DAYS...AND THUS WILL GO WITH SOME
30 POPS BUT STILL KEEPING CHANCES FAIRLY LOW AT THIS TIME RANGE.
ESPECIALLY THE ECMWF SUGGESTS THAT A MODEST SHORTWAVE TROUGH COULD
DROP IN FROM THE NORTHWEST...AND PUSH A WEAK COLD FRONT THROUGH THE
REGION...PROVIDING A BIT MORE FORCING. AGAIN WILL HOLD OFF ON THE
INTRODUCTION OF THUNDERSTORMS AND JUST GO WITH SHOWER WORDING...BUT
THIS WILL BEAR WATCHING AS WEAK INSTABILITY COULD CERTAINLY BE IN
PLACE BY THEN. WILL AIM HIGH TEMPS IN THE 50S AGAIN...BUT DEPENDING
ON HOW TRENDS PLAY OUT WOULD NOT BE SURPRISED TO SEE SOME AREAS
CRACK 60.
&&
.AVIATION...(FOR THE 12Z TAF THROUGH 12Z MONDAY MORNING)
ISSUED AT 543 AM CDT SUN MAR 24 2013
CEILINGS SHOULD REMAIN VFR FOR THE FORECAST FOR THE MOST PART.
AN INCREASE OF LOW-LEVEL LAPSE RATES WILL INCREASE WIND SPEEDS AND GUSTS
FOR TODAY. COULD GET SOME FLURRIES TONIGHT...BUT CHANCES ARE LOW ENOUGH
NOT TO INCLUDE IN THE FORECAST FOR NOW...AND INCLUDED A LOW-LEVEL
SCATTERED LAYER...WHICH WOULD BECOME BROKEN IF FLURRIES DEVELOP.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HALBLAUB
SHORT TERM...HEINLEIN
LONG TERM...PFANNKUCH
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
157 AM EDT SUN MAR 24 2013
.SYNOPSIS...
A COLD MOIST NORTHWEST FLOW...WILL KEEP SCATTERED SNOW SHOWERS
AND FLURRIES ACROSS MUCH OF THE AREA...INTO EARLY SUNDAY.
THEREAFTER...HIGH PRESSURE WILL BRIEFLY BUILD IN...TO BRING DRY
WEATHER MOST OF SUNDAY AND SUNDAY NIGHT. ON MONDAY...A COMPLEX
STORM SYSTEM IS EXPECTED TO ORGANIZE...ALONG THE MID-ATLANTIC
COAST. THIS SYSTEM HAS THE POTENTIAL...TO BRING SNOW TO PORTIONS
OF THE REGION...WITH THE GREATEST LIKELIHOOD OF ACCUMULATING
SNOWFALL...OVER NORTHEAST PENNSYLVANIA.
&&
.NEAR TERM /THROUGH TODAY/...
1 AM UPDATE...
FCST IN GREAT SHAPE...NO SIGNIFICANT CHANGES NEEDED AT THE PRESENT
TIME. LIGHT LAKE EFFECT SNOWS CONTINUING THIS HR ACROSS PORTIONS
OF CENTRAL NY. ACTIVITY WILL CONTINUE THROUGH THE EARLY MORNING
HRS BEFORE DISSIPATING BY MID TO LATE MORNING. SUNDAY SHAPING UP
TO BE A DECENT DAY WITH SOME CLEARING SKIES EXPECTED DURING THE
EARLY AFTERNOON BEFORE CLOUDS AGAIN MOVE IN TONIGHT. FOCUS STILL
REMAINS ON STORM SYSTEM THAT WILL BE IMPACTING SOUTHERN PORTIONS
OF THE FCST AREA EARLY MON MORNING. MORE DETAILS WITH THE 4 AM
UPDATE.
1010 PM UPDATE...
TEMPS WERE RAISED ABOUT A DEGREE OVERNIGHT DUE TO LAKE ENHANCED
CLOUDS AND FLURRIES STREAMING ACROSS INTERIOR FA. PULLED BACK ON
THE POPS OVER NORTHERN FA EARLY, CONFINING MOST OF THE ACTIVITY TO
SE OF THE FINGER LAKES. BASED ON RAP AND WRFARW WIND PROFILES,
TREND THE SNOW SHOWERS BACK NORTHWARD AS THE ACTIVITY WANES LATE
OVERNIGHT.
750 PM UPDATE...
OPTED TO INCREASE POPS TONIGHT AS LES HAS BLOSSOMED AFTER SUNSET.
HOWEVER SAW NO REASON TO INCREASE SNOW AMOUNTS DUE TO VERY LIGHT
SNOWFALL AND LACK OF SNOW GROWTH. EXTENDED FLURRY ACTIVITY TO THE
SOUTH INTO THE WYOMING VALLEY OF PA.
TEMPS/WINDS IN EXCELLENT SHAPE.
325 PM UPDATE... MULTI-BAND LES REMAINS ACRS PTNS OF CNY LATE THIS
AFTN...ALTHOUGH INTENSITY/ORGANIZATION HAS BEEN COMPROMISED BY
BOTH DECREASING MOISTURE SUPPLY...AND DIURNAL HEATING/BLYR INSTAB.
ALTHOUGH TERRESTRIAL STABILITY WILL INCREASE AGN THIS
EVE...MOISTURE SUPPLY WILL REMAIN FAIRLY SHALLOW...SO MAINLY JUST
FLRYS AND SCTD -SHSN ARE ANTICIPATED OVERNIGHT INTO EARLY
SUN...WITH LITTLE TO NO ADDTNL ACCUMS.
MUCH OF THE DAY SUN SHOULD BE PCPN-FREE...WITH BREAKS OF SUNSHINE
BY AFTN...AS A SFC RIDGE NOSES DOWN FROM ERN CANADA. HIGH TEMPS
WILL REMAIN CHILLY...DESPITE SOME SUN...WITH THE AMS ONLY
SUPPORTING READINGS IN THE UPR 30S TO LWR 40S.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
345 PM UPDATE... THE MAIN SYSTEM OF INTEREST REMAINS THE WV
TRACKING EWD FROM THE OH/TN VLYS TWDS THE MID-ATL COAST LTR SUN
NGT THROUGH MON. NWP CONSENSUS CONTS TO SUGGEST AN UNPHASED SYSTEM
(SEPARATE NRN AND SRN STREAMS) TIL QUITE LATE IN THE EVENT (MON
NGT INTO TUE)...ONCE THE SYSTEM IS ALREADY OFF THE ERN SEABOARD.
ALSO...THE PERSISTENCE OF AN UPR-LVL VORTEX NEAR THE CANADIAN
MARITIMES (CONFLUENT FLOW UNDERNEATH IT)...SHOULD MEAN A FAIRLY
QUICK EXIT TO THE E...ONCE THE CYCLONE REACHES THE MD/VA COASTAL
WATERS.
BOTTOM LN...A QUICK SHOT OF LIFT AND MOISTURE ADVECTION DURG THE
DAY MON...WILL LIKELY BRING A SHORT-LIVED PD OF SNOW. OWING TO
THE PRESENCE OF THE MARITIME UPR LOW MENTIONED ABV...IT APPEARS
THERE IS ONLY SO FAR N THE PCPN SHIELD WILL BE ABLE TO GO...AND
CURRENT MODEL CONSENSUS PAINTS THIS "LINE IN THE SAND" NEAR THE
PA/NY BORDER. POP/QPF/SNOW GRIDS WERE ONLY TWEAKED SLIGHTLY FROM
PERSISTENCE...WITH LIKELY POPS MAINLY CONFINED TO NE PA/SULLIVAN
CNTY...WHERE 1-4" OF SNOW COULD POTENTIALLY FALL. FARTHER N ACRS
CNY...LTL OR NO SNOWFALL SEEMS LIKE THE MOST LIKELY OUTCOME ATTM.
WE`LL CONTINUE TO HIGHLIGHT THIS SYSTEM FOR OUR SRN ZNS IN THE
HWO.
BY TUE...WITH THE COASTAL CYCLONE WELL TO OUR E...A WEAK N TO NW
FLOW WILL RESUME...WITH MORE FLRYS/-SHSN IN THE VICINITY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LTL CHG FROM PREV FCST WITH THE RGN REMAINING UNDER NW FLOW (AFTER
THE DEPARTURE OF THE EARLY WEEK MID ATLC CST STORM)...AND GNRL
UPR LVL TROFFINESS. HPC DATA WAS UTILIZED AS THE BASELINE FCST...BUT
WE ADJUSTED SOME MID-WEEK CLD/POP GRIDS TO INDICATE LOW CHC POPS FOR
-SHSN IN THIS NW FLOW PTRN ACRS CNTRL NY. A VERY GRADUAL MODIFICATION
OF THE COLD TEMPS BY LATE IN THE WORK WEEK.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
NORTHWEST FLOW WILL CONTINUE THROUGH EARLY AFTERNOON BRINGING LAKE
MOISTURE ACROSS THE AREA WITH STRATO CU PERSISTING. IN GENERAL THE
STRATO CU WILL REMAIN LOW VFR BUT BETWEEN 09Z-13Z FLURRIES AND
MVFR CIGS WILL BE POSSIBLE AT ALL TAF SITES BUT KELM/KAVP. THIS
AFTERNOON AS THE FLOW BECOMES N/NE LOW CLOUDS WILL SCATTER OUT AS
CI OVERSPREADS THE REGION. THIS EVENING MID/HIGH CLOUDS WILL
THICKEN OVER THE AREA AS A STORM SYSTEM APPROACHES FROM THE
SOUTH.
N/NW WINDS AROUND 10 KNOTS BECOMING LIGHT AND VARIABLE THIS EVENING.
.OUTLOOK...
MON/MON NGT...MVFR CNTRL NY IN -SHSN...IFR/MVFR NE PA IN SNOW.
TUE/WED/THU/FRI...PATCHY MVFR IN -SHSN MAINLY CNTRL NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJP/MLJ
NEAR TERM...CMG/MLJ
SHORT TERM...MLJ
LONG TERM...
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
104 AM EDT SUN MAR 24 2013
.SYNOPSIS...
A COLD MOIST NORTHWEST FLOW...WILL KEEP SCATTERED SNOW SHOWERS
AND FLURRIES ACROSS MUCH OF THE AREA...INTO EARLY SUNDAY.
THEREAFTER...HIGH PRESSURE WILL BRIEFLY BUILD IN...TO BRING DRY
WEATHER MOST OF SUNDAY AND SUNDAY NIGHT. ON MONDAY...A COMPLEX
STORM SYSTEM IS EXPECTED TO ORGANIZE...ALONG THE MID-ATLANTIC
COAST. THIS SYSTEM HAS THE POTENTIAL...TO BRING SNOW TO PORTIONS
OF THE REGION...WITH THE GREATEST LIKELIHOOD OF ACCUMULATING
SNOWFALL...OVER NORTHEAST PENNSYLVANIA.
&&
.NEAR TERM /THROUGH TODAY/...
1 AM UPDATE...
FCST IN GREAT SHAPE...NO SIGNIFICANT CHANGES NEEDED AT THE PRESENT
TIME. LIGHT LAKE EFFECT SNOWS CONTINUING THIS HR ACROSS PORTIONS
OF CENTRAL NY. ACTIVITY WILL CONTINUE THROUGH THE EARLY MORNING
HRS BEFORE DISSIPATING BY MID TO LATE MORNING. SUNDAY SHAPING UP
TO BE A DECENT DAY WITH SOME CLEARING SKIES EXPECTED DURING THE
EARLY AFTERNOON BEFORE CLOUDS AGAIN MOVE IN TONIGHT. FOCUS STILL
REMAINS ON STORM SYSTEM THAT WILL BE IMPACTING SOUTHERN PORTIONS
OF THE FCST AREA EARLY MON MORNING. MORE DETAILS WITH THE 4 AM
UPDATE.
1010 PM UPDATE...
TEMPS WERE RAISED ABOUT A DEGREE OVERNIGHT DUE TO LAKE ENHANCED
CLOUDS AND FLURRIES STREAMING ACROSS INTERIOR FA. PULLED BACK ON
THE POPS OVER NORTHERN FA EARLY, CONFINING MOST OF THE ACTIVITY TO
SE OF THE FINGER LAKES. BASED ON RAP AND WRFARW WIND PROFILES,
TREND THE SNOW SHOWERS BACK NORTHWARD AS THE ACTIVITY WANES LATE
OVERNIGHT.
750 PM UPDATE...
OPTED TO INCREASE POPS TONIGHT AS LES HAS BLOSSOMED AFTER SUNSET.
HOWEVER SAW NO REASON TO INCREASE SNOW AMOUNTS DUE TO VERY LIGHT
SNOWFALL AND LACK OF SNOW GROWTH. EXTENDED FLURRY ACTIVITY TO THE
SOUTH INTO THE WYOMING VALLEY OF PA.
TEMPS/WINDS IN EXCELLENT SHAPE.
325 PM UPDATE... MULTI-BAND LES REMAINS ACRS PTNS OF CNY LATE THIS
AFTN...ALTHOUGH INTENSITY/ORGANIZATION HAS BEEN COMPROMISED BY
BOTH DECREASING MOISTURE SUPPLY...AND DIURNAL HEATING/BLYR INSTAB.
ALTHOUGH TERRESTRIAL STABILITY WILL INCREASE AGN THIS
EVE...MOISTURE SUPPLY WILL REMAIN FAIRLY SHALLOW...SO MAINLY JUST
FLRYS AND SCTD -SHSN ARE ANTICIPATED OVERNIGHT INTO EARLY
SUN...WITH LITTLE TO NO ADDTNL ACCUMS.
MUCH OF THE DAY SUN SHOULD BE PCPN-FREE...WITH BREAKS OF SUNSHINE
BY AFTN...AS A SFC RIDGE NOSES DOWN FROM ERN CANADA. HIGH TEMPS
WILL REMAIN CHILLY...DESPITE SOME SUN...WITH THE AMS ONLY
SUPPORTING READINGS IN THE UPR 30S TO LWR 40S.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
345 PM UPDATE... THE MAIN SYSTEM OF INTEREST REMAINS THE WV
TRACKING EWD FROM THE OH/TN VLYS TWDS THE MID-ATL COAST LTR SUN
NGT THROUGH MON. NWP CONSENSUS CONTS TO SUGGEST AN UNPHASED SYSTEM
(SEPARATE NRN AND SRN STREAMS) TIL QUITE LATE IN THE EVENT (MON
NGT INTO TUE)...ONCE THE SYSTEM IS ALREADY OFF THE ERN SEABOARD.
ALSO...THE PERSISTENCE OF AN UPR-LVL VORTEX NEAR THE CANADIAN
MARITIMES (CONFLUENT FLOW UNDERNEATH IT)...SHOULD MEAN A FAIRLY
QUICK EXIT TO THE E...ONCE THE CYCLONE REACHES THE MD/VA COASTAL
WATERS.
BOTTOM LN...A QUICK SHOT OF LIFT AND MOISTURE ADVECTION DURG THE
DAY MON...WILL LIKELY BRING A SHORT-LIVED PD OF SNOW. OWING TO
THE PRESENCE OF THE MARITIME UPR LOW MENTIONED ABV...IT APPEARS
THERE IS ONLY SO FAR N THE PCPN SHIELD WILL BE ABLE TO GO...AND
CURRENT MODEL CONSENSUS PAINTS THIS "LINE IN THE SAND" NEAR THE
PA/NY BORDER. POP/QPF/SNOW GRIDS WERE ONLY TWEAKED SLIGHTLY FROM
PERSISTENCE...WITH LIKELY POPS MAINLY CONFINED TO NE PA/SULLIVAN
CNTY...WHERE 1-4" OF SNOW COULD POTENTIALLY FALL. FARTHER N ACRS
CNY...LTL OR NO SNOWFALL SEEMS LIKE THE MOST LIKELY OUTCOME ATTM.
WE`LL CONTINUE TO HIGHLIGHT THIS SYSTEM FOR OUR SRN ZNS IN THE
HWO.
BY TUE...WITH THE COASTAL CYCLONE WELL TO OUR E...A WEAK N TO NW
FLOW WILL RESUME...WITH MORE FLRYS/-SHSN IN THE VICINITY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LTL CHG FROM PREV FCST WITH THE RGN REMAINING UNDER NW FLOW (AFTER
THE DEPARTURE OF THE EARLY WEEK MID ATLC CST STORM)...AND GNRL
UPR LVL TROFFINESS. HPC DATA WAS UTILIZED AS THE BASELINE FCST...BUT
WE ADJUSTED SOME MID-WEEK CLD/POP GRIDS TO INDICATE LOW CHC POPS FOR
-SHSN IN THIS NW FLOW PTRN ACRS CNTRL NY. A VERY GRADUAL MODIFICATION
OF THE COLD TEMPS BY LATE IN THE WORK WEEK.
&&
.AVIATION /05Z SUNDAY THROUGH THURSDAY/...
NW FLOW WILL CONT THRU THE PD BRINGING LAKE MOISTURE INTO THE
REGION. THIS WILL RESULT IN OCNL LGT SNOW SHWRS...ALONG WITH NGT
TIME MVFR CIGS. DAYLIGHT HRS WILL BRING BETTER MIXING AND LL DRY
AIR SO CIGS WILL RETURN TO VFR LVLS. FLOW WILL SUPPORT NW
WINDS...BCMG GUSTY DURING THE DAYLIGHT HRS.
.OUTLOOK...
SUN NGT...PATCHY MVFR CNTRL NY.
MON/MON NGT...MVFR CNTRL NY IN -SHSN...IFR/MVFR NE PA IN SNOW.
TUE/WED/THU/FRI...PATCHY MVFR IN -SHSN MAINLY CNTRL NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJP/MLJ
NEAR TERM...CMG/MLJ
SHORT TERM...MLJ
LONG TERM...
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS RALEIGH NC
323 PM EDT SUN MAR 24 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER THE MISSISSIPPI RIVER VALLEY WILL MOVE
NORTHEAST INTO THE OHIO VALLEY TONIGHT. A SECOND AREA OF LOW
PRESSURE WILL DEVELOP NEAR CAPE FEAR THIS AFTERNOON AND MOVE SLOWLY
UP THE COAST TO NEAR NEW JERSEY BY MONDAY AFTERNOON. A COOL
NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
AS OF 300 PM SUNDAY...
THROUGH TONIGHT:
THE SURFACE LOW THAT DEVELOPED OVER THE SOUTHERN MISSISSIPPI RIVER
VALLEY OVERNIGHT HAS SPLIT INTO TWO SEPARATE LOWS...WITH ONE
DEEPENING AS IT MOVES NORTHEAST ALONG THE WEST SIDE OF THE
APPALACHIANS...AND THE SECOND MOVING OFF THE SE ATLANTIC COAST. AS
THE LOW CONTINUES TO MOVE OFF AND ALONG THE ATLANTIC COAST...UPPER
LEVEL WINDS SHOULD BRIEFLY BACK AROUND TO MORE SOUTHEASTERLY BEFORE
THE PARENT LOW OVER THE OHIO RIVER VALLEY MOVES EAST THROUGH THE MID
ATLANTIC. THE HRRR AND THE HIRES WRF-ARW CONVECTION ALLOWING
MODELS...WHICH ARE CAPTURING THE CURRENT REFLECTIVITIES BEST...
INDICATE AN AREA OF SHOWERS DEVELOPING AHEAD OF THE COLD FRONT
TONIGHT. AS SUCH...CONTINUE GRADUALLY DECREASING PRECIP CHANCES
ACROSS THE SOUTH AND EAST THIS AFTERNOON AND FROM WEST TO EAST
ACROSS THE AREA BEHIND THE FRONT OVERNIGHT. HPC GUIDANCE RAINFALL
AMOUNTS APPEAR TO BE A BIT OVERDONE. THUS HAVE GONE MORE TOWARD THE
TREND OF THE HRRR...GIVEN THE DRY SLOT MOVING INTO THE WEST AND THE
FORECAST REFLECTIVITIES FROM THE CONVECTION ALLOWING MODELS. WITH
THE HYBRID COLD AIR DAMMING EVENT LINGERING INTO TONIGHT...WILL SEE
NEAR STEADY TEMPS SLOWLY FALL AFTER SUNSET INTO THE LOW 30S NORTH TO
MID 30S SOUTH AND EAST BY DAYBREAK. THERE IS STILL SOME CONCERN THAT
THE BOUNDARY LAYER MAY COOL ENOUGH TO REACH FREEZING MONDAY MORNING
IN THE TRIAD AREA WHICH COULD RESULT IN SOME BLACK ICE. CONFIDENCE
IN THIS OCCURRING IS STILL LOW AT THIS TIME GIVEN THAT BOUNDARY
LAYER WINDS SHOULD STAY UP AROUND 5 KTS OR SO OVERNIGHT...WHICH WILL
LIMIT SURFACE COOLING AND MAY DRY THINGS OUT ENOUGH TO MITIGATE ANY
BLACK ICE FORMATION. ALSO...IT APPEARS THAT SKIES SHOULD REMAIN
CLOUDY THROUGH DAYBREAK...LIMITING RADIATIONAL COOLING.
MONDAY AND MONDAY NIGHT:
EXPECT THE LOW ALONG THE ATLANTIC COAST TO MERGE WITH THE INLAND LOW
MOVING EAST ACROSS THE MID ATLANTIC ON MONDAY...WITH LINGERING
CHANCES FOR SOME LIGHT RAINFALL/SPRINKLES ACROSS THE NORTH...MAINLY
IN THE AFTERNOON. WITH WINDS BACKING BEHIND THE FRONT AND COLDER AIR
ADVECTING INTO CENTRAL NC...EXPECT HIGH TEMPS IN THE MID TO UPPER
40S NORTH TO MID 50S ACROSS THE SOUTH. WINDS WILL BE STRONG AND
GUSTY OUT OF THE WNW ON MONDAY AND INTO MONDAY NIGHT...EXPECTING
SUSTAINED AT 15-20 KTS...GUSTING TO AROUND 30 KTS. MONDAY NIGHT LOWS
IN THE LOW TO MID 30S...WITH SOME OF THE OUTLYING AREAS POTENTIALLY
DIPPING INTO THE UPPER 20S.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 315 PM SUNDAY...
THE PATTERN ALOFT WILL CHANGE LITTLE - ANOTHER MID-UPPER
LOW...ANOTHER DAY. THIS ONE...CENTERED OVER THE NORTHERN PLAINS THIS
AFTERNOON...WILL SHEAR EASTWARD ACROSS THE SOUTHERN APPALACHIANS AND
NC DURING THE DAY TUE - ON A FAVORABLE TRACK FOR A LITTLE LIGHT
PRECIPITATION FOR CENTRAL NC. DESPITE THE FAVORABLE TRACK AND
ASSOCIATED DYNAMICS...PROJECTED THERMODYNAMICS...AS CHARACTERIZED BY
MID LEVEL (H85-5) LAPSE RATES OF ONLY AROUND 5.5 C/KM...HAVE TRENDED
MUCH WEAKER. NONETHELESS...RELATIVELY DEEP MIXED PHASE SATURATION
BETWEEN 5 AND 15 THOUSAND FT AMIDST POCKETS OF WEAK INSTABILITY ON
THE ORDER OF AROUND 100 OR SO J/KG...SHOULD SUPPORT THE DEVELOPMENT
OF DIURNALLY-ENHANCED SCATTERED SHOWERS...OR SPRINKLES OWING TO A
DRY ADIABATIC...4 THOUSAND FT SUB-CLOUD LAYER. WILL ACCORDINGLY
RETAIN THE SLIGHT TO LOW CHANCE PROBABILITY OF A FEW HUNDREDTHS OF
AN INCH LIQUID...WITH THE LOWEST CHANCES ACROSS THE SOUTHERN
PIEDMONT WHERE THE DEPTH OF THE MOISTURE IS FORECAST TO BE
SHALLOWER/WARMER. IF PRECIPITATION WERE TO OCCUR BEFORE 10-11
AM...WHICH IS UNLIKELY GIVEN THE ABSENCE OF DIURNALLY-DRIVEN WEAK
INSTABILITY BEFORE THAT TIME...THERE WOULD BE THE POTENTIAL FOR A
LITTLE SNOW MIXED WITH THE RAIN OVER THE WESTERN PIEDMONT.
REGARDLESS...NO IMPACT WOULD OCCUR GIVEN THE MARCH SUN ANGLE...AND
TEMPERATURES "WARMING" INTO THE MIDDLE 40S NORTH TO LOWER 50S
SOUTH...BENEATH A CLOUDY OR MOSTLY SO SKY. CLEARING AND COLD TUE
NIGHT...WITH LOWS IN THE UPPER 20S TO LOWER 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 255 PM SUNDAY...
NORTHWEST FLOW AND SLOWLY RISING HEIGHTS ALOFT...AS THE EASTERN
CONUS TROUGH GRADUALLY RELAXES...WILL RULE THROUGH THE MEDIUM RANGE.
BOTH CLIMATOLOGY AND NWP GUIDANCE SUGGEST THIS PERIOD WILL
CONSEQUENTLY BE DRY...AND COOLER THAN AVERAGE...THOUGH TRENDING BACK
INTO THE 60S SUN. THE CHILLIEST TEMPERATURES WILL BE THU AND FRI
NIGHTS AS THE SURFACE RIDGE DRIFTS OVERHEAD...WITH COOLEST READINGS
IN THE MID-UPPER 20S OVER THE WESTERN PIEDMONT FRI MORNING. IT STILL
APPEARS THE GULF OF MEXICO WILL BE BRIEFLY OPEN AHEAD OF A S/W
TROUGH AMPLIFYING THROUGH THE GREAT LAKES THIS WEEKEND...BUT
TIMING...AND DEGREE OF MOISTURE EAST OF THE MOUNTAINS AMIDST DEEP
LAYER WNW FLOW...REMAINS UNCERTAIN. AS SUCH...THE FORECAST WILL
BE KEPT DRY DURING THE WEEKEND.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 222 PM SUNDAY...
24 HOUR TAF PERIOD:
HIGH CONFIDENCE THAT LOW END MVFR TO IFR CIGS AND VISBYS WILL
CONTINUE INTO THE OVERNIGHT HOURS AS RAIN CONTINUES TO FALL. SHOULD
SEE A BREAK IN THE RAINFALL FROM SW TO NW LATE THIS AFTERNOON...
HOWEVER THERE WILL BE LITTLE...IF ANY...IMPROVEMENT IN AVIATION
CONDITIONS DURING THIS TIME. ANOTHER ROUND OF RAINFALL...THIS TIME
MORE SHOWERY IN NATURE...WILL MOVE THROUGH FROM WEST TO EAST AHEAD
OF A COLD FRONT OVERNIGHT. AS THE FRONT MOVES THROUGH IT WILL SCOUR
OUT THE LOW CLOUDS AND CEILINGS YIELDING IMPROVING AVIATION
CONDITIONS AFTER DAYBREAK. WILL SEE A DECREASE IN WINDS OVERNIGHT AS
THE THEY BACK FROM NE TO NW. THEREAFTER...LOW END VFR CONDITIONS
SHOULD PREVAIL THROUGH THE END OF THE TAF PERIOD...WITH THE MAIN
CONCERN LATE MONDAY MORNING TO EARLY MONDAY AFTERNOON BEING STRONG
GUSTY WINDS...MAINLY OUT OF THE WEST/NORTHWEST.
LOOKING AHEAD:
CONDITIONS THROUGH TUESDAY WEDNESDAY WILL BE SOMEWHAT UNSETTLED AND
THE CHANCE FOR A RAIN OR SNOW SHOWER ACROSS THE NORTH ON MONDAY AND
TUESDAY WITH A DECREASE IN CIGS CANNOT BE COMPLETELY RULED OUT.
OTHERWISE...EXPECT MAINLY BROKEN TO OVERCAST VFR CONDITIONS THROUGH
WEDNESDAY...WITH DECREASING CLOUDS THEREAFTER.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...KC
SHORT TERM...MWS
LONG TERM...MWS
AVIATION...KC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
303 PM EDT SUN MAR 24 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER THE MISSISSIPPI RIVER VALLEY WILL MOVE
NORTHEAST INTO THE OHIO VALLEY TONIGHT. A SECOND AREA OF LOW
PRESSURE WILL DEVELOP NEAR CAPE FEAR THIS AFTERNOON AND MOVE SLOWLY
UP THE COAST TO NEAR NEW JERSEY BY MONDAY AFTERNOON. A COOL
NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
AS OF 300 PM SUNDAY...
THROUGH TONIGHT:
THE SURFACE LOW THAT DEVELOPED OVER THE SOUTHERN MISSISSIPPI RIVER
VALLEY OVERNIGHT HAS SPLIT INTO TWO SEPARATE LOWS...WITH ONE
DEEPENING AS IT MOVES NORTHEAST ALONG THE WEST SIDE OF THE
APPALACHIANS...AND THE SECOND MOVING OFF THE SE ATLANTIC COAST. AS
THE LOW CONTINUES TO MOVE OFF AND ALONG THE ATLANTIC COAST...UPPER
LEVEL WINDS SHOULD BRIEFLY BACK AROUND TO MORE SOUTHEASTERLY BEFORE
THE PARENT LOW OVER THE OHIO RIVER VALLEY MOVES EAST THROUGH THE MID
ATLANTIC. THE HRRR AND THE HIRES WRF-ARW CONVECTION ALLOWING
MODELS...WHICH ARE CAPTURING THE CURRENT REFLECTIVITIES BEST...
INDICATE AN AREA OF SHOWERS DEVELOPING AHEAD OF THE COLD FRONT
TONIGHT. AS SUCH...CONTINUE GRADUALLY DECREASING PRECIP CHANCES
ACROSS THE SOUTH AND EAST THIS AFTERNOON AND FROM WEST TO EAST
ACROSS THE AREA BEHIND THE FRONT OVERNIGHT. HPC GUIDANCE RAINFALL
AMOUNTS APPEAR TO BE A BIT OVERDONE. THUS HAVE GONE MORE TOWARD THE
TREND OF THE HRRR...GIVEN THE DRY SLOT MOVING INTO THE WEST AND THE
FORECAST REFLECTIVITIES FROM THE CONVECTION ALLOWING MODELS. WITH
THE HYBRID COLD AIR DAMMING EVENT LINGERING INTO TONIGHT...WILL SEE
NEAR STEADY TEMPS SLOWLY FALL AFTER SUNSET INTO THE LOW 30S NORTH TO
MID 30S SOUTH AND EAST BY DAYBREAK. THERE IS STILL SOME CONCERN THAT
THE BOUNDARY LAYER MAY COOL ENOUGH TO REACH FREEZING MONDAY MORNING
IN THE TRIAD AREA WHICH COULD RESULT IN SOME BLACK ICE. CONFIDENCE
IN THIS OCCURRING IS STILL LOW AT THIS TIME GIVEN THAT BOUNDARY
LAYER WINDS SHOULD STAY UP AROUND 5 KTS OR SO OVERNIGHT...WHICH WILL
LIMIT SURFACE COOLING AND MAY DRY THINGS OUT ENOUGH TO MITIGATE ANY
BLACK ICE FORMATION. ALSO...IT APPEARS THAT SKIES SHOULD REMAIN
CLOUDY THROUGH DAYBREAK...LIMITING RADIATIONAL COOLING.
MONDAY AND MONDAY NIGHT:
EXPECT THE LOW ALONG THE ATLANTIC COAST TO MERGE WITH THE INLAND LOW
MOVING EAST ACROSS THE MID ATLANTIC ON MONDAY...WITH LINGERING
CHANCES FOR SOME LIGHT RAINFALL/SPRINKLES ACROSS THE NORTH...MAINLY
IN THE AFTERNOON. WITH WINDS BACKING BEHIND THE FRONT AND COLDER AIR
ADVECTING INTO CENTRAL NC...EXPECT HIGH TEMPS IN THE MID TO UPPER
40S NORTH TO MID 50S ACROSS THE SOUTH. WINDS WILL BE STRONG AND
GUSTY OUT OF THE WNW ON MONDAY AND INTO MONDAY NIGHT...EXPECTING
SUSTAINED AT 15-20 KTS...GUSTING TO AROUND 30 KTS. MONDAY NIGHT LOWS
IN THE LOW TO MID 30S...WITH SOME OF THE OUTLYING AREAS POTENTIALLY
DIPPING INTO THE UPPER 20S.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 315 AM SUNDAY...
THE AFOREMENTIONED STRONG MID/UPPER LEVEL PV ANOMALY WILL MOVE
THROUGH THE CAROLINAS ON A MORE SOUTHERN TRACK THAN THE INITIAL
UPPER LOW PASSAGE THE DAY BEFORE(MONDAY). THIS MORE SOUTHERN TRACK
WILL RESULT IN BETTER CHANCES OF SEEING SOME MEASURABLE PRECIP
ACROSS CENTRAL NC ON TUESDAY. NAM/GFS BUFR BUFKIT SOUNDINGS SHOW A
DECENT SIZE DENDRITIC GROWTH ZONE THAT IS ABOUT 75MB DEEP ACROSS THE
NORTHERN HALF OF THE FORECAST AREA THROUGH MIDDAY TUESDAY(~18Z).
IF THE PRECIP STARTS EARLY ENOUGH IN THE MORNING...NORTHERN PORTIONS
OF THE FORECAST AREA COULD DEFINITELY SEE A QUICK PASSING SNOW
SHOWER...WITH IT BECOMING INCREASING MIXED WITH RAIN LATER INTO THE
DAY AS TEMPERATURES IN THE SHALLOW ABOVE FREEZING LAYER
ONCE AGAIN WARM INTO THE MID-UPPER 40S...TO LOWER 50S SOUTH.
NO ACCUMULATIONS ARE EXPECTED.
CLOUDS WILL FINALLY CLEAR OUT TUESDAY NIGHT WITH PRESSURE GRADIENT
RELAXING AS WELL. LOWS IN THE UPPER 20S TO LOWER 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 255 PM SUNDAY...
NORTHWEST FLOW AND SLOWLY RISING HEIGHTS ALOFT...AS THE EASTERN
CONUS TROUGH GRADUALLY RELAXES...WILL RULE THROUGH THE MEDIUM RANGE.
BOTH CLIMATOLOGY AND NWP GUIDANCE SUGGEST THIS PERIOD WILL
CONSEQUENTLY BE DRY...AND COOLER THAN AVERAGE...THOUGH TRENDING BACK
INTO THE 60S SUN. THE CHILLIEST TEMPERATURES WILL BE THU AND FRI
NIGHTS AS THE SURFACE RIDGE DRIFTS OVERHEAD...WITH COOLEST READINGS
IN THE MID-UPPER 20S OVER THE WESTERN PIEDMONT FRI MORNING. IT STILL
APPEARS THE GULF OF MEXICO WILL BE BRIEFLY OPEN AHEAD OF A S/W
TROUGH AMPLIFYING THROUGH THE GREAT LAKES THIS WEEKEND...BUT
TIMING...AND DEGREE OF MOISTURE EAST OF THE MOUNTAINS AMIDST DEEP
LAYER WNW FLOW...REMAINS UNCERTAIN. AS SUCH...THE FORECAST WILL
BE KEPT DRY DURING THE WEEKEND.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 222 PM SUNDAY...
24 HOUR TAF PERIOD:
HIGH CONFIDENCE THAT LOW END MVFR TO IFR CIGS AND VISBYS WILL
CONTINUE INTO THE OVERNIGHT HOURS AS RAIN CONTINUES TO FALL. SHOULD
SEE A BREAK IN THE RAINFALL FROM SW TO NW LATE THIS AFTERNOON...
HOWEVER THERE WILL BE LITTLE...IF ANY...IMPROVEMENT IN AVIATION
CONDITIONS DURING THIS TIME. ANOTHER ROUND OF RAINFALL...THIS TIME
MORE SHOWERY IN NATURE...WILL MOVE THROUGH FROM WEST TO EAST AHEAD
OF A COLD FRONT OVERNIGHT. AS THE FRONT MOVES THROUGH IT WILL SCOUR
OUT THE LOW CLOUDS AND CEILINGS YIELDING IMPROVING AVIATION
CONDITIONS AFTER DAYBREAK. WILL SEE A DECREASE IN WINDS OVERNIGHT AS
THE THEY BACK FROM NE TO NW. THEREAFTER...LOW END VFR CONDITIONS
SHOULD PREVAIL THROUGH THE END OF THE TAF PERIOD...WITH THE MAIN
CONCERN LATE MONDAY MORNING TO EARLY MONDAY AFTERNOON BEING STRONG
GUSTY WINDS...MAINLY OUT OF THE WEST/NORTHWEST.
LOOKING AHEAD:
CONDITIONS THROUGH TUESDAY WEDNESDAY WILL BE SOMEWHAT UNSETTLED AND
THE CHANCE FOR A RAIN OR SNOW SHOWER ACROSS THE NORTH ON MONDAY AND
TUESDAY WITH A DECREASE IN CIGS CANNOT BE COMPLETELY RULED OUT.
OTHERWISE...EXPECT MAINLY BROKEN TO OVERCAST VFR CONDITIONS THROUGH
WEDNESDAY...WITH DECREASING CLOUDS THEREAFTER.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...KC
SHORT TERM...CBL
LONG TERM...MWS
AVIATION...KC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
258 PM EDT SUN MAR 24 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER THE MISSISSIPPI RIVER VALLEY WILL MOVE
NORTHEAST INTO THE OHIO VALLEY TONIGHT. A SECOND AREA OF LOW
PRESSURE WILL DEVELOP NEAR CAPE FEAR THIS AFTERNOON AND MOVE SLOWLY
UP THE COAST TO NEAR NEW JERSEY BY MONDAY AFTERNOON. A COOL
NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1100 AM SUNDAY...
TODAY:
THE SURFACE LOW THAT DEVELOPED OVER THE SOUTHERN MISSISSIPPI RIVER
VALLEY OVERNIGHT WILL CONTINUE TO SPLIT INTO TWO SEPARATE LOWS AS IT
MOVES NORTH AND EAST THIS MORNING. THE WESTERN MOST LOW WILL DEEPEN
AS IT MOVES NORTHEAST ALONG THE WEST SIDE OF THE APPALACHIANS...
WHILE THE SECOND WILL INTENSIFY OFF THE SE ATLANTIC COAST AND
MIGRATE NE ALONG IT. ALTHOUGH SOME LIGHT TO MODERATE RAIN HAS MOVED
INTO CENTRAL NC THIS MORNING...THE STRONGEST CONVECTION AND HEAVIEST
RAINFALL HAS REMAINED SOUTH OF THE AREA. 12Z UPPER AIR ANALYSES SHOW
THE H85 LOW ALREADY SPLITTING...WITH SOME INDICATION OF THE
SECONDARY LOW AT 700 MB. CENTRAL NC IS UNDER THE RIGHT REAR QUADRANT
OF THE 150+ KT UPPER LEVEL JET...WITH A SECOND JET...WITH WINDS JUST
UNDER 150 KTS...TO THE SOUTHEAST. WHILE SURFACE WINDS ARE MAINLY ENE
TO NE ACROSS THE AREA...UPPER LEVEL WINDS ARE SOUTH AND SW. AS THE
LOW MOVES OFF THE ATLANTIC COAST UPPER LEVEL WINDS SHOULD BRIEFLY
BACK AROUND TO MORE SOUTHEASTERLY BEFORE THE LOW...INITIALLY TO THE
WEST OF THE APPALACHIANS...MOVES EAST THROUGH THE MID ATLANTIC. THE
10Z HRRR AND THE 00Z HIRES WRF-ARW CONVECTION ALLOWING MODELS...
WHICH ARE CAPTURING THE CURRENT REFLECTIVITIES BEST...INDICATE AN
AREA OF LIGHT RAINFALL FILLING IN BEHIND THE BREAK...MAINLY ACROSS
THE NORTH AND NORTHWEST WITH SOME SHOWERS POSSIBLE THROUGH TONIGHT.
AS SUCH...CONTINUE WITH 100 PERCENT CHANCE FOR RAIN INTO THE
AFTERNOON WITH CHANCES GRADUALLY DECREASING ACROSS THE WEST AND
SOUTH THIS AFT/EVE. WHILE RAINFALL AMOUNTS ARE NOT ENTIRELY
CERTAIN...HPC GUIDANCE APPEARS TO BE A BIT OVERDONE. GIVEN THE DRY
SLOT MOVING INTO THE WEST AND THE FORECAST REFLECTIVITIES FROM THE
CONVECTION ALLOWING MODELS...WILL HAVE RAINFALL AMOUNTS LESS THAN
GUIDANCE...WITH HIGHEST TOTALS ACROSS THE NORTH. -KC
WITH THE HYBRID COLD AIR DAMMING EVENT TODAY AND TONIGHT...
TEMPERATURES WILL FEATURE VERY LITTLE DIURNAL RANGE...ESPECIALLY IN
THE HEART OF THE DAMMING REGION. HIGHS SHOULD RANGE IN THE UPPER 30S
IN THE NW PIEDMONT TO THE MID 40S IN THE SOUTHERN COASTAL PLAIN.
TEMPERATURES TONIGHT WILL FEATURE ONLY A MODEST DROP OFF WITH LOWS
TONIGHT WILL RANGING FROM THE LOWER/MID 30S ACROSS THE NORTHWEST TO
UPPER 30S SOUTHEAST. -BLAES
TONIGHT:
THE LAST BATCH OF SHOWERS...POSSIBLY INCLUDING SOME SHALLOW
CONVECTION WILL SWING EAST AND NORTHEAST THROUGH CENTRAL NC BETWEEN
02-08Z. WITH ANY LINGERING PRECIPITATION HUGGING THE VA BORDER OR
PERHAPS SOME PATCHY DRIZZLE. THERE IS SOME CONCERN THAT THE BOUNDARY
LAYER MAY COOL ENOUGH TO REACH FREEZING ON MONDAY MORNING IN THE
TRIAD AREA WHICH COULD RESULT IN SOME BLACK ICE. WHILE THE NEAR
SURFACE FLOW IS BECOMING SOUTHWEST/WEST AND DRYING...IT APPEARS THAT
SKIES SHOULD REMAIN CLOUDY THROUGH DAYBREAK LIMITING RADIATIONAL
COOLING. SUBSEQUENT SHIFTS WILL NEED TO MONITOR THE POTENTIAL FOR
SOME CLEARING AND A SUDDEN DROP IN SURFACE TEMPS AT DAYBREAK
ALTHOUGH THIS APPEARS UNLIKELY AS TURBULENT MIXING WILL LIKELY BE
ONGOING AND LIMIT SFC COOLING. -BLAES
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 315 AM SUNDAY...
MONDAY AND MONDAY NIGHT:
THE INLAND SFC LOW(OVER THE TN/OH VALLEY)ASSOCIATED WITH THE MILLER
B STORM SYSTEM WILL QUICKLY GIVE WAY TO THE RAPIDLY INTENSIFYING
SECONDARY LOW LIFTING NORTHWARD UP THE MID ATLC COAST MONDAY
MORNING. AS THE SYSTEM GAINS NORTHERN LATITUDE...THE RESULTANT
WEST-NWLY LOW-LEVEL FLOW WILL ADVECT COLDER-DRIER AIR INTO THE
AREA...SCOURING OUT THE RESIDUAL DAMMING AIRMASS LEADING TO PARTIAL
OR SHORT-LIVED CLEARING THROUGH THE FIRST HALF OF THE DAY ON MONDAY
BEFORE THE ARRIVAL OF THE UPPER LOW DYNAMICS BRINGS RENEW MID/UPPER
LEVEL LIFT MONDAY AFTERNOON. MOISTURE WILL BE LIMITED HOWEVER AND
WILL LIKELY SUPPORT ONLY SPRINKLES...AND QUITE POSSIBLY A WET FLAKE
OR TWO ACROSS NORTHERN PORTIONS OF THE FORECAST AREA MONDAY
AFTERNOON. HIGHS IN THE MID TO UPPER 40S NORTH TO LOWER 50S SOUTH
WITH BLUSTERY WESTERLY WINDS OF 20 MPH...GUSTING TO 30 MPH AT TIMES.
EXPECT A BRIEF LULL ACROSS CENTRAL NC IN THE WAKE OF THE UPPER LOW
EXITING OFF THE DELMARVA COAST MONDAY EVENING...BEFORE THE ARRIVAL
OF A STRONG MID/UPPER LEVEL PV ANOMALY INTO THE SOUTHERN APPALACHIANS
BY DAYBREAK TUESDAY. ANY PRECIP SHOULD HOLD OFF UNTIL DAYBREAK
TUESDAY SO WILL KEEP FORECAST DRY WHILE HOLDING ON TO AMPLE CLOUD
COVER. LOWS IN THE UPPER 20 TO LOWER 30S.
TUESDAY AND TUESDAY NIGHT:
THE AFOREMENTIONED STRONG MID/UPPER LEVEL PV ANOMALY WILL MOVE
THROUGH THE CAROLINAS ON A MORE SOUTHERN TRACK THAN THE INITIAL
UPPER LOW PASSAGE THE DAY BEFORE(MONDAY). THIS MORE SOUTHERN TRACK
WILL RESULT IN BETTER CHANCES OF SEEING SOME MEASURABLE PRECIP
ACROSS CENTRAL NC ON TUESDAY. NAM/GFS BUFR BUFKIT SOUNDINGS SHOW A
DECENT SIZE DENDRITIC GROWTH ZONE THAT IS ABOUT 75MB DEEP ACROSS THE
NORTHERN HALF OF THE FORECAST AREA THROUGH MIDDAY TUESDAY(~18Z).
IF THE PRECIP STARTS EARLY ENOUGH IN THE MORNING...NORTHERN PORTIONS
OF THE FORECAST AREA COULD DEFINITELY SEE A QUICK PASSING SNOW
SHOWER...WITH IT BECOMING INCREASING MIXED WITH RAIN LATER INTO THE
DAY AS TEMPERATURES IN THE SHALLOW ABOVE FREEZING LAYER
ONCE AGAIN WARM INTO THE MID-UPPER 40S...TO LOWER 50S SOUTH.
NO ACCUMULATIONS ARE EXPECTED.
CLOUDS WILL FINALLY CLEAR OUT TUESDAY NIGHT WITH PRESSURE GRADIENT
RELAXING AS WELL. LOWS IN THE UPPER 20S TO LOWER 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 255 PM SUNDAY...
NORTHWEST FLOW AND SLOWLY RISING HEIGHTS ALOFT...AS THE EASTERN
CONUS TROUGH GRADUALLY RELAXES...WILL RULE THROUGH THE MEDIUM RANGE.
BOTH CLIMATOLOGY AND NWP GUIDANCE SUGGEST THIS PERIOD WILL
CONSEQUENTLY BE DRY...AND COOLER THAN AVERAGE...THOUGH TRENDING BACK
INTO THE 60S SUN. THE CHILLIEST TEMPERATURES WILL BE THU AND FRI
NIGHTS AS THE SURFACE RIDGE DRIFTS OVERHEAD...WITH COOLEST READINGS
IN THE MID-UPPER 20S OVER THE WESTERN PIEDMONT FRI MORNING. IT STILL
APPEARS THE GULF OF MEXICO WILL BE BRIEFLY OPEN AHEAD OF A S/W
TROUGH AMPLIFYING THROUGH THE GREAT LAKES THIS WEEKEND...BUT
TIMING...AND DEGREE OF MOISTURE EAST OF THE MOUNTAINS AMIDST DEEP
LAYER WNW FLOW...REMAINS UNCERTAIN. AS SUCH...THE FORECAST WILL
BE KEPT DRY DURING THE WEEKEND.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 222 PM SUNDAY...
24 HOUR TAF PERIOD:
HIGH CONFIDENCE THAT LOW END MVFR TO IFR CIGS AND VISBYS WILL
CONTINUE INTO THE OVERNIGHT HOURS AS RAIN CONTINUES TO FALL. SHOULD
SEE A BREAK IN THE RAINFALL FROM SW TO NW LATE THIS AFTERNOON...
HOWEVER THERE WILL BE LITTLE...IF ANY...IMPROVEMENT IN AVIATION
CONDITIONS DURING THIS TIME. ANOTHER ROUND OF RAINFALL...THIS TIME
MORE SHOWERY IN NATURE...WILL MOVE THROUGH FROM WEST TO EAST AHEAD
OF A COLD FRONT OVERNIGHT. AS THE FRONT MOVES THROUGH IT WILL SCOUR
OUT THE LOW CLOUDS AND CEILINGS YIELDING IMPROVING AVIATION
CONDITIONS AFTER DAYBREAK. WILL SEE A DECREASE IN WINDS OVERNIGHT AS
THE THEY BACK FROM NE TO NW. THEREAFTER...LOW END VFR CONDITIONS
SHOULD PREVAIL THROUGH THE END OF THE TAF PERIOD...WITH THE MAIN
CONCERN LATE MONDAY MORNING TO EARLY MONDAY AFTERNOON BEING STRONG
GUSTY WINDS...MAINLY OUT OF THE WEST/NORTHWEST.
LOOKING AHEAD:
CONDITIONS THROUGH TUESDAY WEDNESDAY WILL BE SOMEWHAT UNSETTLED AND
THE CHANCE FOR A RAIN OR SNOW SHOWER ACROSS THE NORTH ON MONDAY AND
TUESDAY WITH A DECREASE IN CIGS CANNOT BE COMPLETELY RULED OUT.
OTHERWISE...EXPECT MAINLY BROKEN TO OVERCAST VFR CONDITIONS THROUGH
WEDNESDAY...WITH DECREASING CLOUDS THEREAFTER.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...KC/BLAES
SHORT TERM...CBL
LONG TERM...MWS
AVIATION...KC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
223 PM EDT SUN MAR 24 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER THE MISSISSIPPI RIVER VALLEY WILL MOVE
NORTHEAST INTO THE OHIO VALLEY TONIGHT. A SECOND AREA OF LOW
PRESSURE WILL DEVELOP NEAR CAPE FEAR THIS AFTERNOON AND MOVE SLOWLY
UP THE COAST TO NEAR NEW JERSEY BY MONDAY AFTERNOON. A COOL
NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1100 AM SUNDAY...
TODAY:
THE SURFACE LOW THAT DEVELOPED OVER THE SOUTHERN MISSISSIPPI RIVER
VALLEY OVERNIGHT WILL CONTINUE TO SPLIT INTO TWO SEPARATE LOWS AS IT
MOVES NORTH AND EAST THIS MORNING. THE WESTERN MOST LOW WILL DEEPEN
AS IT MOVES NORTHEAST ALONG THE WEST SIDE OF THE APPALACHIANS...
WHILE THE SECOND WILL INTENSIFY OFF THE SE ATLANTIC COAST AND
MIGRATE NE ALONG IT. ALTHOUGH SOME LIGHT TO MODERATE RAIN HAS MOVED
INTO CENTRAL NC THIS MORNING...THE STRONGEST CONVECTION AND HEAVIEST
RAINFALL HAS REMAINED SOUTH OF THE AREA. 12Z UPPER AIR ANALYSES SHOW
THE H85 LOW ALREADY SPLITTING...WITH SOME INDICATION OF THE
SECONDARY LOW AT 700 MB. CENTRAL NC IS UNDER THE RIGHT REAR QUADRANT
OF THE 150+ KT UPPER LEVEL JET...WITH A SECOND JET...WITH WINDS JUST
UNDER 150 KTS...TO THE SOUTHEAST. WHILE SURFACE WINDS ARE MAINLY ENE
TO NE ACROSS THE AREA...UPPER LEVEL WINDS ARE SOUTH AND SW. AS THE
LOW MOVES OFF THE ATLANTIC COAST UPPER LEVEL WINDS SHOULD BRIEFLY
BACK AROUND TO MORE SOUTHEASTERLY BEFORE THE LOW...INITIALLY TO THE
WEST OF THE APPALACHIANS...MOVES EAST THROUGH THE MID ATLANTIC. THE
10Z HRRR AND THE 00Z HIRES WRF-ARW CONVECTION ALLOWING MODELS...
WHICH ARE CAPTURING THE CURRENT REFLECTIVITIES BEST...INDICATE AN
AREA OF LIGHT RAINFALL FILLING IN BEHIND THE BREAK...MAINLY ACROSS
THE NORTH AND NORTHWEST WITH SOME SHOWERS POSSIBLE THROUGH TONIGHT.
AS SUCH...CONTINUE WITH 100 PERCENT CHANCE FOR RAIN INTO THE
AFTERNOON WITH CHANCES GRADUALLY DECREASING ACROSS THE WEST AND
SOUTH THIS AFT/EVE. WHILE RAINFALL AMOUNTS ARE NOT ENTIRELY
CERTAIN...HPC GUIDANCE APPEARS TO BE A BIT OVERDONE. GIVEN THE DRY
SLOT MOVING INTO THE WEST AND THE FORECAST REFLECTIVITIES FROM THE
CONVECTION ALLOWING MODELS...WILL HAVE RAINFALL AMOUNTS LESS THAN
GUIDANCE...WITH HIGHEST TOTALS ACROSS THE NORTH. -KC
WITH THE HYBRID COLD AIR DAMMING EVENT TODAY AND TONIGHT...
TEMPERATURES WILL FEATURE VERY LITTLE DIURNAL RANGE...ESPECIALLY IN
THE HEART OF THE DAMMING REGION. HIGHS SHOULD RANGE IN THE UPPER 30S
IN THE NW PIEDMONT TO THE MID 40S IN THE SOUTHERN COASTAL PLAIN.
TEMPERATURES TONIGHT WILL FEATURE ONLY A MODEST DROP OFF WITH LOWS
TONIGHT WILL RANGING FROM THE LOWER/MID 30S ACROSS THE NORTHWEST TO
UPPER 30S SOUTHEAST. -BLAES
TONIGHT:
THE LAST BATCH OF SHOWERS...POSSIBLY INCLUDING SOME SHALLOW
CONVECTION WILL SWING EAST AND NORTHEAST THROUGH CENTRAL NC BETWEEN
02-08Z. WITH ANY LINGERING PRECIPITATION HUGGING THE VA BORDER OR
PERHAPS SOME PATCHY DRIZZLE. THERE IS SOME CONCERN THAT THE BOUNDARY
LAYER MAY COOL ENOUGH TO REACH FREEZING ON MONDAY MORNING IN THE
TRIAD AREA WHICH COULD RESULT IN SOME BLACK ICE. WHILE THE NEAR
SURFACE FLOW IS BECOMING SOUTHWEST/WEST AND DRYING...IT APPEARS THAT
SKIES SHOULD REMAIN CLOUDY THROUGH DAYBREAK LIMITING RADIATIONAL
COOLING. SUBSEQUENT SHIFTS WILL NEED TO MONITOR THE POTENTIAL FOR
SOME CLEARING AND A SUDDEN DROP IN SURFACE TEMPS AT DAYBREAK
ALTHOUGH THIS APPEARS UNLIKELY AS TURBULENT MIXING WILL LIKELY BE
ONGOING AND LIMIT SFC COOLING. -BLAES
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 315 AM SUNDAY...
MONDAY AND MONDAY NIGHT:
THE INLAND SFC LOW(OVER THE TN/OH VALLEY)ASSOCIATED WITH THE MILLER
B STORM SYSTEM WILL QUICKLY GIVE WAY TO THE RAPIDLY INTENSIFYING
SECONDARY LOW LIFTING NORTHWARD UP THE MID ATLC COAST MONDAY
MORNING. AS THE SYSTEM GAINS NORTHERN LATITUDE...THE RESULTANT
WEST-NWLY LOW-LEVEL FLOW WILL ADVECT COLDER-DRIER AIR INTO THE
AREA...SCOURING OUT THE RESIDUAL DAMMING AIRMASS LEADING TO PARTIAL
OR SHORT-LIVED CLEARING THROUGH THE FIRST HALF OF THE DAY ON MONDAY
BEFORE THE ARRIVAL OF THE UPPER LOW DYNAMICS BRINGS RENEW MID/UPPER
LEVEL LIFT MONDAY AFTERNOON. MOISTURE WILL BE LIMITED HOWEVER AND
WILL LIKELY SUPPORT ONLY SPRINKLES...AND QUITE POSSIBLY A WET FLAKE
OR TWO ACROSS NORTHERN PORTIONS OF THE FORECAST AREA MONDAY
AFTERNOON. HIGHS IN THE MID TO UPPER 40S NORTH TO LOWER 50S SOUTH
WITH BLUSTERY WESTERLY WINDS OF 20 MPH...GUSTING TO 30 MPH AT TIMES.
EXPECT A BRIEF LULL ACROSS CENTRAL NC IN THE WAKE OF THE UPPER LOW
EXITING OFF THE DELMARVA COAST MONDAY EVENING...BEFORE THE ARRIVAL
OF A STRONG MID/UPPER LEVEL PV ANOMALY INTO THE SOUTHERN APPALACHIANS
BY DAYBREAK TUESDAY. ANY PRECIP SHOULD HOLD OFF UNTIL DAYBREAK
TUESDAY SO WILL KEEP FORECAST DRY WHILE HOLDING ON TO AMPLE CLOUD
COVER. LOWS IN THE UPPER 20 TO LOWER 30S.
TUESDAY AND TUESDAY NIGHT:
THE AFOREMENTIONED STRONG MID/UPPER LEVEL PV ANOMALY WILL MOVE
THROUGH THE CAROLINAS ON A MORE SOUTHERN TRACK THAN THE INITIAL
UPPER LOW PASSAGE THE DAY BEFORE(MONDAY). THIS MORE SOUTHERN TRACK
WILL RESULT IN BETTER CHANCES OF SEEING SOME MEASURABLE PRECIP
ACROSS CENTRAL NC ON TUESDAY. NAM/GFS BUFR BUFKIT SOUNDINGS SHOW A
DECENT SIZE DENDRITIC GROWTH ZONE THAT IS ABOUT 75MB DEEP ACROSS THE
NORTHERN HALF OF THE FORECAST AREA THROUGH MIDDAY TUESDAY(~18Z).
IF THE PRECIP STARTS EARLY ENOUGH IN THE MORNING...NORTHERN PORTIONS
OF THE FORECAST AREA COULD DEFINITELY SEE A QUICK PASSING SNOW
SHOWER...WITH IT BECOMING INCREASING MIXED WITH RAIN LATER INTO THE
DAY AS TEMPERATURES IN THE SHALLOW ABOVE FREEZING LAYER
ONCE AGAIN WARM INTO THE MID-UPPER 40S...TO LOWER 50S SOUTH.
NO ACCUMULATIONS ARE EXPECTED.
CLOUDS WILL FINALLY CLEAR OUT TUESDAY NIGHT WITH PRESSURE GRADIENT
RELAXING AS WELL. LOWS IN THE UPPER 20S TO LOWER 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 315 AM SUNDAY...
WITH THE HIGH-LATITUDE BLOCK REMAINING IN PLACE...TEMPERATURES WILL
BE VERY SLOW TO MODERATE UNDERNEATH THE NEGATIVE HEIGHT ANOMALIES
ANCHORED ALONG THE EASTERN CONUS/WESTERN ATLANTIC. THUS...COOL-BELOW
NORMAL TEMPERATURES WILL CONTINUE THROUGH THE END OF THE WORK
WEEK...WITH AT OR BELOW FREEZING MINS EACH NIGHT. AS HEIGHTS BEGIN
TO INCREASE ALOFT AND THE CANADIAN SFC HIGH SHIFTS EAST OF THE
AREA...DAYTIME TEMPERATURES WILL LOOK TO FINALLY REBOUND INTO THE
LOWER 60S.
DISTURBANCES IN THE NW FLOW ALOFT ON THE BACK-SIDE OF THE UPPER
TROUGH OVER THE WESTERN ATLANTIC COULD BRING EPISODIC CLOUDINESS
BUT IT SHOULD REMAIN DRY THROUGH THE PERIOD.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 222 PM SUNDAY...
24 HOUR TAF PERIOD:
HIGH CONFIDENCE THAT LOW END MVFR TO IFR CIGS AND VISBYS WILL
CONTINUE INTO THE OVERNIGHT HOURS AS RAIN CONTINUES TO FALL. SHOULD
SEE A BREAK IN THE RAINFALL FROM SW TO NW LATE THIS AFTERNOON...
HOWEVER THERE WILL BE LITTLE...IF ANY...IMPROVEMENT IN AVIATION
CONDITIONS DURING THIS TIME. ANOTHER ROUND OF RAINFALL...THIS TIME
MORE SHOWERY IN NATURE...WILL MOVE THROUGH FROM WEST TO EAST AHEAD
OF A COLD FRONT OVERNIGHT. AS THE FRONT MOVES THROUGH IT WILL SCOUR
OUT THE LOW CLOUDS AND CEILINGS YIELDING IMPROVING AVIATION
CONDITIONS AFTER DAYBREAK. WILL SEE A DECREASE IN WINDS OVERNIGHT AS
THE THEY BACK FROM NE TO NW. THEREAFTER...LOW END VFR CONDITIONS
SHOULD PREVAIL THROUGH THE END OF THE TAF PERIOD...WITH THE MAIN
CONCERN LATE MONDAY MORNING TO EARLY MONDAY AFTERNOON BEING STRONG
GUSTY WINDS...MAINLY OUT OF THE WEST/NORTHWEST.
LOOKING AHEAD:
CONDITIONS THROUGH TUESDAY WEDNESDAY WILL BE SOMEWHAT UNSETTLED AND
THE CHANCE FOR A RAIN OR SNOW SHOWER ACROSS THE NORTH ON MONDAY AND
TUESDAY WITH A DECREASE IN CIGS CANNOT BE COMPLETELY RULED OUT.
OTHERWISE...EXPECT MAINLY BROKEN TO OVERCAST VFR CONDITIONS THROUGH
WEDNESDAY...WITH DECREASING CLOUDS THEREAFTER.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...KC/BLAES
SHORT TERM...CBL
LONG TERM...CBL
AVIATION...KC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1100 AM EDT SUN MAR 24 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER THE MISSISSIPPI RIVER VALLEY WILL MOVE
NORTHEAST INTO THE OHIO VALLEY TONIGHT. A SECOND AREA OF LOW
PRESSURE WILL DEVELOP NEAR CAPE FEAR THIS AFTERNOON AND MOVE SLOWLY
UP THE COAST TO NEAR NEW JERSEY BY MONDAY AFTERNOON. A COOL
NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1100 AM SUNDAY...
TODAY:
THE SURFACE LOW THAT DEVELOPED OVER THE SOUTHERN MISSISSIPPI RIVER
VALLEY OVERNIGHT WILL CONTINUE TO SPLIT INTO TWO SEPARATE LOWS AS IT
MOVES NORTH AND EAST THIS MORNING. THE WESTERN MOST LOW WILL DEEPEN
AS IT MOVES NORTHEAST ALONG THE WEST SIDE OF THE APPALACHIANS...
WHILE THE SECOND WILL INTENSIFY OFF THE SE ATLANTIC COAST AND
MIGRATE NE ALONG IT. ALTHOUGH SOME LIGHT TO MODERATE RAIN HAS MOVED
INTO CENTRAL NC THIS MORNING...THE STRONGEST CONVECTION AND HEAVIEST
RAINFALL HAS REMAINED SOUTH OF THE AREA. 12Z UPPER AIR ANALYSES SHOW
THE H85 LOW ALREADY SPLITTING...WITH SOME INDICATION OF THE
SECONDARY LOW AT 700 MB. CENTRAL NC IS UNDER THE RIGHT REAR QUADRANT
OF THE 150+ KT UPPER LEVEL JET...WITH A SECOND JET...WITH WINDS JUST
UNDER 150 KTS...TO THE SOUTHEAST. WHILE SURFACE WINDS ARE MAINLY ENE
TO NE ACROSS THE AREA...UPPER LEVEL WINDS ARE SOUTH AND SW. AS THE
LOW MOVES OFF THE ATLANTIC COAST UPPER LEVEL WINDS SHOULD BRIEFLY
BACK AROUND TO MORE SOUTHEASTERLY BEFORE THE LOW...INITIALLY TO THE
WEST OF THE APPALACHIANS...MOVES EAST THROUGH THE MID ATLANTIC. THE
10Z HRRR AND THE 00Z HIRES WRF-ARW CONVECTION ALLOWING MODELS...
WHICH ARE CAPTURING THE CURRENT REFLECTIVITIES BEST...INDICATE AN
AREA OF LIGHT RAINFALL FILLING IN BEHIND THE BREAK...MAINLY ACROSS
THE NORTH AND NORTHWEST WITH SOME SHOWERS POSSIBLE THROUGH TONIGHT.
AS SUCH...CONTINUE WITH 100 PERCENT CHANCE FOR RAIN INTO THE
AFTERNOON WITH CHANCES GRADUALLY DECREASING ACROSS THE WEST AND
SOUTH THIS AFT/EVE. WHILE RAINFALL AMOUNTS ARE NOT ENTIRELY
CERTAIN...HPC GUIDANCE APPEARS TO BE A BIT OVERDONE. GIVEN THE DRY
SLOT MOVING INTO THE WEST AND THE FORECAST REFLECTIVITIES FROM THE
CONVECTION ALLOWING MODELS...WILL HAVE RAINFALL AMOUNTS LESS THAN
GUIDANCE...WITH HIGHEST TOTALS ACROSS THE NORTH. -KC
WITH THE HYBRID COLD AIR DAMMING EVENT TODAY AND TONIGHT...
TEMPERATURES WILL FEATURE VERY LITTLE DIURNAL RANGE...ESPECIALLY IN
THE HEART OF THE DAMMING REGION. HIGHS SHOULD RANGE IN THE UPPER 30S
IN THE NW PIEDMONT TO THE MID 40S IN THE SOUTHERN COASTAL PLAIN.
TEMPERATURES TONIGHT WILL FEATURE ONLY A MODEST DROP OFF WITH LOWS
TONIGHT WILL RANGING FROM THE LOWER/MID 30S ACROSS THE NORTHWEST TO
UPPER 30S SOUTHEAST. -BLAES
TONIGHT:
THE LAST BATCH OF SHOWERS...POSSIBLY INCLUDING SOME SHALLOW
CONVECTION WILL SWING EAST AND NORTHEAST THROUGH CENTRAL NC BETWEEN
02-08Z. WITH ANY LINGERING PRECIPITATION HUGGING THE VA BORDER OR
PERHAPS SOME PATCHY DRIZZLE. THERE IS SOME CONCERN THAT THE BOUNDARY
LAYER MAY COOL ENOUGH TO REACH FREEZING ON MONDAY MORNING IN THE
TRIAD AREA WHICH COULD RESULT IN SOME BLACK ICE. WHILE THE NEAR
SURFACE FLOW IS BECOMING SOUTHWEST/WEST AND DRYING...IT APPEARS THAT
SKIES SHOULD REMAIN CLOUDY THROUGH DAYBREAK LIMITING RADIATIONAL
COOLING. SUBSEQUENT SHIFTS WILL NEED TO MONITOR THE POTENTIAL FOR
SOME CLEARING AND A SUDDEN DROP IN SURFACE TEMPS AT DAYBREAK
ALTHOUGH THIS APPEARS UNLIKELY AS TURBULENT MIXING WILL LIKELY BE
ONGOING AND LIMIT SFC COOLING. -BLAES
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 315 AM SUNDAY...
MONDAY AND MONDAY NIGHT:
THE INLAND SFC LOW(OVER THE TN/OH VALLEY)ASSOCIATED WITH THE MILLER
B STORM SYSTEM WILL QUICKLY GIVE WAY TO THE RAPIDLY INTENSIFYING
SECONDARY LOW LIFTING NORTHWARD UP THE MID ATLC COAST MONDAY
MORNING. AS THE SYSTEM GAINS NORTHERN LATITUDE...THE RESULTANT
WEST-NWLY LOW-LEVEL FLOW WILL ADVECT COLDER-DRIER AIR INTO THE
AREA...SCOURING OUT THE RESIDUAL DAMMING AIRMASS LEADING TO PARTIAL
OR SHORT-LIVED CLEARING THROUGH THE FIRST HALF OF THE DAY ON MONDAY
BEFORE THE ARRIVAL OF THE UPPER LOW DYNAMICS BRINGS RENEW MID/UPPER
LEVEL LIFT MONDAY AFTERNOON. MOISTURE WILL BE LIMITED HOWEVER AND
WILL LIKELY SUPPORT ONLY SPRINKLES...AND QUITE POSSIBLY A WET FLAKE
OR TWO ACROSS NORTHERN PORTIONS OF THE FORECAST AREA MONDAY
AFTERNOON. HIGHS IN THE MID TO UPPER 40S NORTH TO LOWER 50S SOUTH
WITH BLUSTERY WESTERLY WINDS OF 20 MPH...GUSTING TO 30 MPH AT TIMES.
EXPECT A BRIEF LULL ACROSS CENTRAL NC IN THE WAKE OF THE UPPER LOW
EXITING OFF THE DELMARVA COAST MONDAY EVENING...BEFORE THE ARRIVAL
OF A STRONG MID/UPPER LEVEL PV ANOMALY INTO THE SOUTHERN APPALACHIANS
BY DAYBREAK TUESDAY. ANY PRECIP SHOULD HOLD OFF UNTIL DAYBREAK
TUESDAY SO WILL KEEP FORECAST DRY WHILE HOLDING ON TO AMPLE CLOUD
COVER. LOWS IN THE UPPER 20 TO LOWER 30S.
TUESDAY AND TUESDAY NIGHT:
THE AFOREMENTIONED STRONG MID/UPPER LEVEL PV ANOMALY WILL MOVE
THROUGH THE CAROLINAS ON A MORE SOUTHERN TRACK THAN THE INITIAL
UPPER LOW PASSAGE THE DAY BEFORE(MONDAY). THIS MORE SOUTHERN TRACK
WILL RESULT IN BETTER CHANCES OF SEEING SOME MEASURABLE PRECIP
ACROSS CENTRAL NC ON TUESDAY. NAM/GFS BUFR BUFKIT SOUNDINGS SHOW A
DECENT SIZE DENDRITIC GROWTH ZONE THAT IS ABOUT 75MB DEEP ACROSS THE
NORTHERN HALF OF THE FORECAST AREA THROUGH MIDDAY TUESDAY(~18Z).
IF THE PRECIP STARTS EARLY ENOUGH IN THE MORNING...NORTHERN PORTIONS
OF THE FORECAST AREA COULD DEFINITELY SEE A QUICK PASSING SNOW
SHOWER...WITH IT BECOMING INCREASING MIXED WITH RAIN LATER INTO THE
DAY AS TEMPERATURES IN THE SHALLOW ABOVE FREEZING LAYER
ONCE AGAIN WARM INTO THE MID-UPPER 40S...TO LOWER 50S SOUTH.
NO ACCUMULATIONS ARE EXPECTED.
CLOUDS WILL FINALLY CLEAR OUT TUESDAY NIGHT WITH PRESSURE GRADIENT
RELAXING AS WELL. LOWS IN THE UPPER 20S TO LOWER 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 315 AM SUNDAY...
WITH THE HIGH-LATITUDE BLOCK REMAINING IN PLACE...TEMPERATURES WILL
BE VERY SLOW TO MODERATE UNDERNEATH THE NEGATIVE HEIGHT ANOMALIES
ANCHORED ALONG THE EASTERN CONUS/WESTERN ATLANTIC. THUS...COOL-BELOW
NORMAL TEMPERATURES WILL CONTINUE THROUGH THE END OF THE WORK
WEEK...WITH AT OR BELOW FREEZING MINS EACH NIGHT. AS HEIGHTS BEGIN
TO INCREASE ALOFT AND THE CANADIAN SFC HIGH SHIFTS EAST OF THE
AREA...DAYTIME TEMPERATURES WILL LOOK TO FINALLY REBOUND INTO THE
LOWER 60S.
DISTURBANCES IN THE NW FLOW ALOFT ON THE BACK-SIDE OF THE UPPER
TROUGH OVER THE WESTERN ATLANTIC COULD BRING EPISODIC CLOUDINESS
BUT IT SHOULD REMAIN DRY THROUGH THE PERIOD.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AS OF 745 AM SUNDAY...
HIGH CONFIDENCE CONTINUES THAT LOW END MVFR/IFR CONDITIONS WILL
OVERSPREAD CENTRAL NC THIS MORNING AND PERSIST FOR MOST OF THE
AFTERNOON AND EVENING HOURS. A LARGE SHIELD OF RAIN WILL CONTINUE TO
OVERSPREAD THE REGION FROM THE SOUTHWEST THIS MORNING. RAIN SHOULD
START AT KRDU WITHIN THE HOUR AND BY 13Z AT KRWI. AFTER THE INITIAL
SURGE...THE WIDESPREAD RAIN WILL EVOLVE TO MORE SHOWER CONDITIONS
WITH LOW END MVFR/IFR CEILINGS AND MVFR VISIBILITIES DURING THE
AFTERNOON. A COLD FRONT WILL MOVE EAST ACROSS CENTRAL NC WELL AFTER
MIDNIGHT TOWARD MONDAY MORNING AND BEGIN ERODING THE LINGERING LOW
CLOUDS AND CEILINGS WILL BEGIN TO RISE TOWARD DAYBREAK..
LOW END MVFR/IFR CONDITIONS ARE EXPECTED TO IMPROVE ON MONDAY
MORNING...ESPECIALLY AFTER DAYBREAK. BUT THE REGION WILL BE IN AN
UNSETTLED PATTERN THAT WILL SUPPORT PERIODS OF SCT-BKN CUMULUS OR
STRATUS WITH MAINLY VFR CEILINGS ON MONDAY THROUGH WEDNESDAY. A RAIN
OR SNOW SHOWER IS POSSIBLE ON MONDAY OR TUESDAY...ESPECIALLY DURING
THE AFTERNOON ACROSS THE NORTH. FAIR WEATHER WITH VFR CONDITIONS ARE
ANTICIPATED ON THURSDAY. -BLAES
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...KC/BLAES
SHORT TERM...CBL
LONG TERM...CBL
AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1059 AM EDT SUN MAR 24 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM OVER THE MISSISSIPPI RIVER VALLEY WILL MOVE
NORTHEAST INTO THE OHIO VALLEY TONIGHT. A SECOND AREA OF LOW
PRESSURE WILL DEVELOP NEAR CAPE FEAR THIS AFTERNOON AND MOVE SLOWLY
UP THE COAST TO NEAR NEW JERSEY BY MONDAY AFTERNOON. A COOL
NORTHWEST FLOW WILL CONTINUE ACROSS THE REGION FOR MONDAY THROUGH
WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1058 AM SUNDAY...
TODAY:
THE SURFACE LOW THAT DEVELOPED OVER THE SOUTHERN MISSISSIPPI RIVER
VALLEY OVERNIGHT WILL CONTINUE TO SPLIT INTO TWO SEPARATE LOWS AS IT
MOVES NORTH AND EAST THIS MORNING. THE WESTERN MOST LOW WILL DEEPEN
AS IT MOVES NORTHEAST ALONG THE WEST SIDE OF THE APPALACHIANS...
WHILE THE SECOND WILL INTENSIFY OFF THE SE ATLANTIC COAST AND
MIGRATE NE ALONG IT. ALTHOUGH SOME LIGHT TO MODERATE RAIN HAS MOVED
INTO CENTRAL NC THIS MORNING...THE STRONGEST CONVECTION AND HEAVIEST
RAINFALL HAS REMAINED SOUTH OF THE AREA. 12Z UPPER AIR ANALYSES SHOW
THE H85 LOW ALREADY SPLITTING...WITH SOME INDICATION OF THE
SECONDARY LOW AT 700 MB. CENTRAL NC IS UNDER THE RIGHT REAR QUADRANT
OF THE 150+ KT UPPER LEVEL JET...WITH ANOTHER JET...WITH A SECOND
JET...WITH WINDS JUST UNDER 150 KTS...TO THE SOUTHEAST. WHILE
SURFACE WINDS ARE MAINLY ENE TO NE ACROSS THE AREA...UPPER LEVEL
WINDS ARE SOUTH AND SW. AS THE LOW MOVES OFF THE ATLANTIC COAST
UPPER LEVEL WINDS SHOULD BRIEFLY BACK AROUND TO MORE SOUTHEASTERLY
BEFORE THE LOW...INITIALLY TO THE WEST OF THE APPALACHIANS...MOVES
EAST THROUGH THE MID ATLANTIC. THE 10Z HRRR AND THE 00Z HIRES
WRF-ARW CONVECTION ALLOWING MODELS...WHICH ARE CAPTURING THE CURRENT
REFLECTIVITIES BEST...INDICATE AN AREA OF LIGHT RAINFALL FILLING IN
BEHIND THE BREAK...MAINLY ACROSS THE NORTH AND NORTHWEST WITH SOME
SHOWERS POSSIBLE THROUGH TONIGHT. AS SUCH...CONTINUE WITH 100
PERCENT CHANCE FOR RAIN INTO THE AFTERNOON WITH CHANCES GRADUALLY
DECREASING ACROSS THE WEST AND SOUTH THIS AFT/EVE. WHILE RAINFALL
AMOUNTS ARE NOT ENTIRELY CERTAIN...HPC GUIDANCE APPEARS TO BE A BIT
OVERDONE. GIVEN THE DRY SLOT MOVING INTO THE WEST AND THE FORECAST
REFLECTIVITIES FROM THE CONVECTION ALLOWING MODELS...WILL HAVE
RAINFALL AMOUNTS LESS THAN GUIDANCE...WITH HIGHEST TOTALS ACROSS THE
NORTH. -KC
WITH THE HYBRID COLD AIR DAMMING EVENT TODAY AND TONIGHT...
TEMPERATURES WILL FEATURE VERY LITTLE DIURNAL RANGE...ESPECIALLY IN
THE HEART OF THE DAMMING REGION. HIGHS SHOULD RANGE IN THE UPPER 30S
IN THE NW PIEDMONT TO THE MID 40S IN THE SOUTHERN COASTAL PLAIN.
TEMPERATURES TONIGHT WILL FEATURE ONLY A MODEST DROP OFF WITH LOWS
TONIGHT WILL RANGING FROM THE LOWER/MID 30S ACROSS THE NORTHWEST TO
UPPER 30S SOUTHEAST. -BLAES
TONIGHT:
THE LAST BATCH OF SHOWERS...POSSIBLY INCLUDING SOME SHALLOW
CONVECTION WILL SWING EAST AND NORTHEAST THROUGH CENTRAL NC BETWEEN
02-08Z. WITH ANY LINGERING PRECIPITATION HUGGING THE VA BORDER OR
PERHAPS SOME PATCHY DRIZZLE. THERE IS SOME CONCERN THAT THE BOUNDARY
LAYER MAY COOL ENOUGH TO REACH FREEZING ON MONDAY MORNING IN THE
TRIAD AREA WHICH COULD RESULT IN SOME BLACK ICE. WHILE THE NEAR
SURFACE FLOW IS BECOMING SOUTHWEST/WEST AND DRYING...IT APPEARS THAT
SKIES SHOULD REMAIN CLOUDY THROUGH DAYBREAK LIMITING RADIATIONAL
COOLING. SUBSEQUENT SHIFTS WILL NEED TO MONITOR THE POTENTIAL FOR
SOME CLEARING AND A SUDDEN DROP IN SURFACE TEMPS AT DAYBREAK
ALTHOUGH THIS APPEARS UNLIKELY AS TURBULENT MIXING WILL LIKELY BE
ONGOING AND LIMIT SFC COOLING. -BLAES
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 315 AM SUNDAY...
MONDAY AND MONDAY NIGHT:
THE INLAND SFC LOW(OVER THE TN/OH VALLEY)ASSOCIATED WITH THE MILLER
B STORM SYSTEM WILL QUICKLY GIVE WAY TO THE RAPIDLY INTENSIFYING
SECONDARY LOW LIFTING NORTHWARD UP THE MID ATLC COAST MONDAY
MORNING. AS THE SYSTEM GAINS NORTHERN LATITUDE...THE RESULTANT
WEST-NWLY LOW-LEVEL FLOW WILL ADVECT COLDER-DRIER AIR INTO THE
AREA...SCOURING OUT THE RESIDUAL DAMMING AIRMASS LEADING TO PARTIAL
OR SHORT-LIVED CLEARING THROUGH THE FIRST HALF OF THE DAY ON MONDAY
BEFORE THE ARRIVAL OF THE UPPER LOW DYNAMICS BRINGS RENEW MID/UPPER
LEVEL LIFT MONDAY AFTERNOON. MOISTURE WILL BE LIMITED HOWEVER AND
WILL LIKELY SUPPORT ONLY SPRINKLES...AND QUITE POSSIBLY A WET FLAKE
OR TWO ACROSS NORTHERN PORTIONS OF THE FORECAST AREA MONDAY
AFTERNOON. HIGHS IN THE MID TO UPPER 40S NORTH TO LOWER 50S SOUTH
WITH BLUSTERY WESTERLY WINDS OF 20 MPH...GUSTING TO 30 MPH AT TIMES.
EXPECT A BRIEF LULL ACROSS CENTRAL NC IN THE WAKE OF THE UPPER LOW
EXITING OFF THE DELMARVA COAST MONDAY EVENING...BEFORE THE ARRIVAL
OF A STRONG MID/UPPER LEVEL PV ANOMALY INTO THE SOUTHERN APPALACHIANS
BY DAYBREAK TUESDAY. ANY PRECIP SHOULD HOLD OFF UNTIL DAYBREAK
TUESDAY SO WILL KEEP FORECAST DRY WHILE HOLDING ON TO AMPLE CLOUD
COVER. LOWS IN THE UPPER 20 TO LOWER 30S.
TUESDAY AND TUESDAY NIGHT:
THE AFOREMENTIONED STRONG MID/UPPER LEVEL PV ANOMALY WILL MOVE
THROUGH THE CAROLINAS ON A MORE SOUTHERN TRACK THAN THE INITIAL
UPPER LOW PASSAGE THE DAY BEFORE(MONDAY). THIS MORE SOUTHERN TRACK
WILL RESULT IN BETTER CHANCES OF SEEING SOME MEASURABLE PRECIP
ACROSS CENTRAL NC ON TUESDAY. NAM/GFS BUFR BUFKIT SOUNDINGS SHOW A
DECENT SIZE DENDRITIC GROWTH ZONE THAT IS ABOUT 75MB DEEP ACROSS THE
NORTHERN HALF OF THE FORECAST AREA THROUGH MIDDAY TUESDAY(~18Z).
IF THE PRECIP STARTS EARLY ENOUGH IN THE MORNING...NORTHERN PORTIONS
OF THE FORECAST AREA COULD DEFINITELY SEE A QUICK PASSING SNOW
SHOWER...WITH IT BECOMING INCREASING MIXED WITH RAIN LATER INTO THE
DAY AS TEMPERATURES IN THE SHALLOW ABOVE FREEZING LAYER
ONCE AGAIN WARM INTO THE MID-UPPER 40S...TO LOWER 50S SOUTH.
NO ACCUMULATIONS ARE EXPECTED.
CLOUDS WILL FINALLY CLEAR OUT TUESDAY NIGHT WITH PRESSURE GRADIENT
RELAXING AS WELL. LOWS IN THE UPPER 20S TO LOWER 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 315 AM SUNDAY...
WITH THE HIGH-LATITUDE BLOCK REMAINING IN PLACE...TEMPERATURES WILL
BE VERY SLOW TO MODERATE UNDERNEATH THE NEGATIVE HEIGHT ANOMALIES
ANCHORED ALONG THE EASTERN CONUS/WESTERN ATLANTIC. THUS...COOL-BELOW
NORMAL TEMPERATURES WILL CONTINUE THROUGH THE END OF THE WORK
WEEK...WITH AT OR BELOW FREEZING MINS EACH NIGHT. AS HEIGHTS BEGIN
TO INCREASE ALOFT AND THE CANADIAN SFC HIGH SHIFTS EAST OF THE
AREA...DAYTIME TEMPERATURES WILL LOOK TO FINALLY REBOUND INTO THE
LOWER 60S.
DISTURBANCES IN THE NW FLOW ALOFT ON THE BACK-SIDE OF THE UPPER
TROUGH OVER THE WESTERN ATLANTIC COULD BRING EPISODIC CLOUDINESS
BUT IT SHOULD REMAIN DRY THROUGH THE PERIOD.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AS OF 745 AM SUNDAY...
HIGH CONFIDENCE CONTINUES THAT LOW END MVFR/IFR CONDITIONS WILL
OVERSPREAD CENTRAL NC THIS MORNING AND PERSIST FOR MOST OF THE
AFTERNOON AND EVENING HOURS. A LARGE SHIELD OF RAIN WILL CONTINUE TO
OVERSPREAD THE REGION FROM THE SOUTHWEST THIS MORNING. RAIN SHOULD
START AT KRDU WITHIN THE HOUR AND BY 13Z AT KRWI. AFTER THE INITIAL
SURGE...THE WIDESPREAD RAIN WILL EVOLVE TO MORE SHOWER CONDITIONS
WITH LOW END MVFR/IFR CEILINGS AND MVFR VISIBILITIES DURING THE
AFTERNOON. A COLD FRONT WILL MOVE EAST ACROSS CENTRAL NC WELL AFTER
MIDNIGHT TOWARD MONDAY MORNING AND BEGIN ERODING THE LINGERING LOW
CLOUDS AND CEILINGS WILL BEGIN TO RISE TOWARD DAYBREAK..
LOW END MVFR/IFR CONDITIONS ARE EXPECTED TO IMPROVE ON MONDAY
MORNING...ESPECIALLY AFTER DAYBREAK. BUT THE REGION WILL BE IN AN
UNSETTLED PATTERN THAT WILL SUPPORT PERIODS OF SCT-BKN CUMULUS OR
STRATUS WITH MAINLY VFR CEILINGS ON MONDAY THROUGH WEDNESDAY. A RAIN
OR SNOW SHOWER IS POSSIBLE ON MONDAY OR TUESDAY...ESPECIALLY DURING
THE AFTERNOON ACROSS THE NORTH. FAIR WEATHER WITH VFR CONDITIONS ARE
ANTICIPATED ON THURSDAY. -BLAES
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...KC/BLAES
SHORT TERM...CBL
LONG TERM...CBL
AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
640 PM EDT SUN MAR 24 2013
.SYNOPSIS...
LOW PRESSURE OVER KENTUCKY WILL MOVE ACROSS SOUTHERN OHIO
OVERNIGHT. THE LOW WILL WEAKEN ON MONDAY AS A NEW LOW DEEPENS
RAPIDLY OFF THE MID ATLANTIC COAST. THIS DEEP LOW WILL EXTEND A
TROUGH WEST ACROSS THE GREAT LAKES REGION INTO WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
UPDATE ALREADY OUT. GIVEN DRY NE FLOW...CURRENT OBS AND LATEST
RADAR HAVE SLOWED DOWN THE ONSET OF THE SNOW A COUPLE OF HOURS
MOST AREAS. CURRENT RADAR RETURNS OVER THE LOCAL AREA ARE JUST
CLOUDS AND VIRGA. THE SNOW SHOULD REACH THE SOUTHERN END OF THE
AREA AFTER 00Z AND KMFD AROUND 03Z. IT WILL BE AFTER MIDNIGHT
BEFORE ANYTHING MORE THAN FLURRIES FALLS IN THE CLEVELAND AREA.
ORIGINAL...GUIDANCE CONVERGING ON A SOLUTION BRINGING THE SURFACE LOW FROM
WESTERN KENTUCKY INTO SOUTHERN OHIO OVERNIGHT. WEAK WAVE
INCREASING RETURN ON THE RADAR ACROSS CENTRAL AND SOUTHERN OHIO
THROUGH THE AFTERNOON. MUCH OF THIS ACROSS THE NORTHWEST AND NORTH
CENTRAL COUNTIES HAS BEEN VIRGA ALTHOUGH THERE ARE POCKETS OF
LIGHT SNOW AS WELL. FOLLOWING THE HRRR THIS PRECIP WILL CONTINUE
TO SPREAD INTO THE AREA BUT THEN WEAKEN AND DISSIPATE EARLY
EVENING. WILL HAVE CHANCE POPS IN PLACE TO COVER THE SNOW WITH
THIS ADVANCE WAVE. OTHERWISE MAIN PRECIP ASSOCIATED WITH THE STORM
SYSTEM NOW MOVING INTO/THRU SRN INDIANA AND ILLINOIS.
AGAIN...FOLLOWING HRRR EXPECT THIS TO MOVE INTO OUR AREA FROM THE
SSW BETWEEN 00-03Z. SNOW WILL CONTINUE TO MOVE INTO THE AREA FROM
THE SOUTH WITH MODERATE SNOW LIKELY COVERING THE SOUTHERN TIER OF
COUNTIES FROM 05Z-10Z. EXPECTING 4-6 INCHES ACROSS THE SOUTHERN
TIER WITH 3-5 FURTHER NORTH IN THE ADVISORY.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/...
ADVISORY/WARNING WILL BE ON GOING AT 12Z WITH SNOW LIKELY OCCURRING
ACROSS MUCH OF THE AREA. EXPECTING ANOTHER COUPLE INCHES ACROSS
THE SOUTH/SOUTHEAST COUNTIES THAT WILL BRING STORM TOTALS IN THE
WARNING AREA TO 5 TO 7...POSSIBLY A FEW 8`S WITH 3 TO 5...POSSIBLY
6 IN THE ADVISORY AREA BY NOON. THROUGH THE AFTERNOON MOISTURE AND
LIFT WILL BE WEAKENING AS THE ENERGY OF THE SYSTEM TRANSLATES TO
THE EAST COAST AND THE OHIO SURFACE LOW FILLS. MONDAY NIGHT
THROUGH TUESDAY NIGHT WILL CONTINUE WITH LOW CHANCE POPS IN A
GENERALLY MOIST NORTHERLY CYCLONIC FLOW...STILL INFLUENCED BY THE
EXITING SURFACE LOW WELL OFF THE EAST COAST. MID WEEK HIGH
PRESSURE WILL TRY TO BUILD IN AS THE LOW GETS HALF WAY TO EUROPE.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A FEW LINGERING SNOW SHOWERS IN THE SNOWBELT ON THURSDAY WITH 850 MB
TEMPS ONLY MINUS 8C. MODELS IN REASONABLE AGREEMENT MOVING HIGH
PRESSURE OVER THE AREA DURING THE DAY ON FRIDAY. HIGH PRESSURE WILL
REMAIN OVER THE AREA WELL INTO THE WEEKEND. MODELS MOVE NEXT
SYSTEM THROUGH ON SUNDAY...LEANED TOWARD THE SLOWER GFS SLOWER.
SHOULD WARM INTO THE 40S ALLOWING FOR RAIN.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
LOW PRESSURE SOUTHEAST OF ST LOUIS WILL TRACK ACROSS SOUTHERN OHIO
OVERNIGHT. THIS WILL BE A SYNOPTIC SITUATION WHERE THE FURTHER
SOUTH...CLOSER TO THE LOW...THE MORE SNOW. OVERNIGHT EXPECT AROUND
2-4 INCHES CLOSE TO THE LAKESHORE WHILE 6+ INCHES ACROSS CENTRAL
OHIO. WIDESPREAD IFR/LIFR IN THE HEAVIER SNOW.
CONDITIONS WILL GRADUALLY IMPROVE FROM THE WEST MONDAY MORNING AS
LOW SHIFTS EAST OF THE AREA.
NORTHEAST WINDS GUSTING INTO THE MID 20S WILL CONTINUE INTO MONDAY.
.OUTLOOK...NON VFR IN SHSN CONTINUING INTO WEDNESDAY.
&&
.MARINE...
LOW PRESSURE OVER KENTUCKY WILL MOVE ACROSS SOUTHERN OHIO TONIGHT.
AS IT DOES WINDS WIND INCREASE TO 20 TO 25 KNOTS ACROSS ENTIRE LAKE.
WINDS TURN TO THE NORTHWEST AS THE LOW MOVES OFF THE MID ATLANTIC
COAST MONDAY AFTERNOON. CONDITIONS DROP BELOW SMALL CRAFT ADVISORY
CRITERIA TUESDAY AS GRADIENT WEAKENS. HIGH PRESSURE FINALLY BUILDS
OVER THE LAKE ON FRIDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...WINTER STORM WARNING UNTIL NOON EDT MONDAY FOR OHZ036>038-047.
WINTER WEATHER ADVISORY UNTIL NOON EDT MONDAY FOR OHZ017>022-
027>033.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT TUESDAY FOR LEZ142>149.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK/KUBINA
SHORT TERM...TK
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
336 PM EDT SUN MAR 24 2013
.SYNOPSIS...
LOW PRESSURE OVER KENTUCKY WILL MOVE ACROSS SOUTHERN OHIO
OVERNIGHT. THE LOW WILL WEAKEN ON MONDAY AS A NEW LOW DEEPENS
RAPIDLY OFF THE MID ATLANTIC COAST. THIS DEEP LOW WILL EXTEND A
TROUGH WEST ACROSS THE GREAT LAKES REGION INTO WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
GUIDANCE CONVERGING ON A SOLUTION BRINGING THE SURFACE LOW FROM
WESTERN KENTUCKY INTO SOUTHERN OHIO OVERNIGHT. WEAK WAVE
INCREASING RETURN ON THE RADAR ACROSS CENTRAL AND SOUTHERN OHIO
THROUGH THE AFTERNOON. MUCH OF THIS ACROSS THE NORTHWEST AND NORTH
CENTRAL COUNTIES HAS BEEN VIRGA ALTHOUGH THERE ARE POCKETS OF LIGHT
SNOW AS WELL. FOLLOWING THE HRRR THIS PRECIP WILL CONTINUE TO
SPREAD INTO THE AREA BUT THEN WEAKEN AND DISSIPATE EARLY EVENING.
WILL HAVE CHANCE POPS IN PLACE TO COVER THE SNOW WITH THIS ADVANCE
WAVE. OTHERWISE MAIN PRECIP ASSOCIATED WITH THE STORM SYSTEM NOW
MOVING INTO/THRU SRN INDIANA AND ILLINOIS. AGAIN...FOLLOWING HRRR
EXPECT THIS TO MOVE INTO OUR AREA FROM THE SSW BETWEEN 00-03Z. SNOW
WILL CONTINUE TO MOVE INTO THE AREA FROM THE SOUTH WITH MODERATE
SNOW LIKELY COVERING THE SOUTHERN TIER OF COUNTIES FROM 05Z-10Z.
EXPECTING 4-6 INCHES ACROSS THE SOUTHERN TIER WITH 3-5 FURTHER
NORTH IN THE ADVISORY.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/...
ADVISORY/WARNING WILL BE ON GOING AT 12Z WITH SNOW LIKELY OCCURRING
ACROSS MUCH OF THE AREA. EXPECTING ANOTHER COUPLE INCHES ACROSS
THE SOUTH/SOUTHEAST COUNTIES THAT WILL BRING STORM TOTALS IN THE
WARNING AREA TO 5 TO 7...POSSIBLY A FEW 8`S WITH 3 TO 5...POSSIBLY
6 IN THE ADVISORY AREA BY NOON. THROUGH THE AFTERNOON MOISTURE AND
LIFT WILL BE WEAKENING AS THE ENERGY OF THE SYSTEM TRANSLATES TO
THE EAST COAST AND THE OHIO SURFACE LOW FILLS. MONDAY NIGHT
THROUGH TUESDAY NIGHT WILL CONTINUE WITH LOW CHANCE POPS IN A
GENERALLY MOIST NORTHERLY CYCLONIC FLOW...STILL INFLUENCED BY THE
EXITING SURFACE LOW WELL OFF THE EAST COAST. MID WEEK HIGH
PRESSURE WILL TRY TO BUILD IN AS THE LOW GETS HALF WAY TO EUROPE.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A FEW LINGERING SNOW SHOWERS IN THE SNOWBELT ON THURSDAY WITH 850 MB
TEMPS ONLY MINUS 8C. MODELS IN REASONABLE AGREEMENT MOVING HIGH
PRESSURE OVER THE AREA DURING THE DAY ON FRIDAY. HIGH PRESSURE WILL
REMAIN OVER THE AREA WELL INTO THE WEEKEND. MODELS MOVE NEXT
SYSTEM THROUGH ON SUNDAY...LEANED TOWARD THE SLOWER GFS SLOWER.
SHOULD WARM INTO THE 40S ALLOWING FOR RAIN.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
LOW PRESSURE SOUTHEAST OF ST LOUIS WILL TRACK ACROSS SOUTHERN OHIO
OVERNIGHT. THIS WILL BE A SYNOPTIC SITUATION WHERE THE FURTHER
SOUTH...CLOSER TO THE LOW...THE MORE SNOW. OVERNIGHT EXPECT AROUND
2-4 INCHES CLOSE TO THE LAKESHORE WHILE 6+ INCHES ACROSS CENTRAL
OHIO. WIDESPREAD IFR/LIFR IN THE HEAVIER SNOW.
CONDITIONS WILL GRADUALLY IMPROVE FROM THE WEST MONDAY MORNING AS
LOW SHIFTS EAST OF THE AREA.
NORTHEAST WINDS GUSTING INTO THE MID 20S WILL CONTINUE INTO MONDAY.
.OUTLOOK...NON VFR IN SHSN CONTINUING INTO WEDNESDAY.
&&
.MARINE...
LOW PRESSURE OVER KENTUCKY WILL MOVE ACROSS SOUTHERN OHIO TONIGHT.
AS IT DOES WINDS WIND INCREASE TO 20 TO 25 KNOTS ACROSS ENTIRE LAKE.
WINDS TURN TO THE NORTHWEST AS THE LOW MOVES OFF THE MID ATLANTIC
COAST MONDAY AFTERNOON. CONDITIONS DROP BELOW SMALL CRAFT ADVISORY
CRITERIA TUESDAY AS GRADIENT WEAKENS. HIGH PRESSURE FINALLY BUILDS
OVER THE LAKE ON FRIDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...WINTER STORM WARNING UNTIL NOON EDT MONDAY FOR OHZ036>038-047.
WINTER WEATHER ADVISORY UNTIL NOON EDT MONDAY FOR OHZ017>022-
027>033.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT TUESDAY FOR LEZ142>149.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
144 PM EDT SUN MAR 24 2013
.SYNOPSIS...
BELOW NORMAL TEMPERATURES THROUGH NEXT WEEK. WINTER STORM AFFECTS
THE AREA TODAY THROUGH LATE MONDAY...BRINGING MAINLY RAIN SUNDAY...
CHANGING TO ALL SNOW MONDAY NIGHT. UPSLOPE SNOW EVENT FOLLOWS.
&&
.NEAR TERM /THROUGH TONIGHT/...
630 AM UPDATE...FRESHENED UP GRIDS A BIT...BUT NO SIGNIFICANT
CHANGES.
PREVIOUS DISCUSSION...
WHAT A COMPLEX SYSTEM. ON THE POSITIVE SIDE...MODELS AGREE VERY WELL
ON THE MASS AND QPF FIELDS OF THE SYSTEM AFFECTING US THIS PERIOD.
PARENT SURFACE LOW LIFTS NORTHEAST INTO SOUTHERN OHIO AHEAD OF A
DEVELOPING STRONG UPPER LOW OVER THE MID MISSISSIPPI VALLEY...THEN
REDEVELOPS LATER TONIGHT JUST OFF THE MID ATLANTIC COAST AS THE
APPROACHING UPPER SYSTEM TAPS INTO THE GULF STREAM WATERS. LOOKS LIKE
ONE SLUG OF QPF THIS AFTERNOON WITH A LEAD SHORT WAVE AND ANOTHER
TONIGHT WITH THE UPPER LOW ITSELF. HOWEVER...THE THERMAL FIELDS WITH
THE SYSTEM DO NOT AGREE WELL...AND THIS IS CRITICAL TO THE TYPE OF
PRECIP IN A QPF REGIME OF BETWEEN HALF AN INCH AND AN INCH.
NORMALLY...I REPEAT NORMALLY...WITH THE TRACK OF THE PARENT SURFACE
LOW WE WOULD EXPECT A BRIEF PERIOD OF WINTRY MIX TO RAIN IN THE
LOWLANDS AS THE TYPICAL WARM WEDGE IN LOW LEVEL SOUTHEASTERLY FLOW
SURGES AHEAD OF THE LOW. WE WOULD KEEP A WINTRY TYPE PRECIP REGIME
IN THE NORTHERN MOUNTAINS WITH THE TYPICAL UPSLOPE AND COLD AIR
DAMMING. WE WOULD THEN SEE A TRANSITION BACK TO SNOW LATER TONIGHT
AS COLDER AIR WORKS IN ALOFT.
HOWEVER...THE TRACK OF THE UPPER SYSTEM IS EAST RIGHT ACROSS OUR
AREA. THIS PREVENTS THE WARM WEDGE FROM GETTING TOO FAR NORTH THIS
AFTERNOON AS THE HEAVIER PRECIP ARRIVES. THE NAM AND RUC ARE THE
WARM OUTLIER FOR THE WARM WEDGE...WHILE THE GFS AND EURO ARE COLDER.
THIS COLDER SCENARIO APPEARS TO BE DUE TO STRONG UPPER DYNAMICS AND
WET BULBING WHIT THE PRECIP. EVEN THE SREF SHOWS THIS.
AM GOING WITH THE COOLER SCENARIO. YES...THE MAV/LAMP TEMP GUIDANCE
CURIOUSLY SHOW HIGHS IN THE 40S FOR MUCH OF THE LOWLANDS TODAY...BUT
THIS IS DISCOUNTED BY THE GUIDANCE NOT SEEMING TO ACCOUNT FOR WET
BULB COOLING. SO WILL ACTUALLY USE THE COOLER NAM SURFACE TEMPS BUT
THE GFS/EURO AND SREF COOLER TEMPS ALOFT.
ALL THIS PANS OUT TO TEMPS TODAY REMAINING IN THE 30S ACROSS THE
MOST OF THE LOWLANDS...WHILE BELOW FREEZING TEMPS OCCUR IN THE
NORTHERN MOUNTAINS. THIS WILL BE COLD ENOUGH FOR ALL SNOW NORTHERN
MOUNTAINS...SNOW WITH MIXED RAIN AND SLEET ACROSS THE FAR
NORTH...AND BRIEF WINTRY MIX TO RAIN ELSEWHERE. WITH THE AMOUNT OF
QPF...COULD BE HEAVY WET SNOW ACROSS THE FAR NORTH. THUS...ISSUED A
WINTER WEATHER ADVISORY FOR THE AREA LATER THIS AFTERNOON AND
ESPECIALLY TONIGHT WITH THE SECOND QPF SLUG. WINTER STORM WARNING
REMAINS IN EFFECT FOR THE NORTHERN MOUNTAINS.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
LOW PRESSURE SYSTEM EXITS TO THE EAST...ONLY TO HAVE CYCLONIC FLOW
REINFORCED BY A SECONDARY TROUGH SWINGING THROUGH THE TENNESSEE
VALLEY INTO THE MID ATLANTIC. IN THE LOWER LEVELS...FLOW WILL TURN
AROUND TO THE NORTHWEST THAT WILL EVENTUALLY TAP INTO SOME GREAT
LAKES MOISTURE. COLD POOL ALOFT WILL SETTLE INTO THE AREA...AND WILL
NOT RELINQUISH ITS GRIP ALL THE WAY INTO MID WEEK...WITH 850MB
TEMPERATURES VARYING FROM -7C TO -10C. IN THE END...THIS RESULTS IN
POPS FOR THE BULK OF THE SHORT TERM FORECAST ENHANCED BY THE
AFOREMENTIONED SECONDARY TROUGH AXIS MONDAY EVENING INTO
TUESDAY...AND THEN THE CONVECTIVE NATURE OF THE NORTHWEST FLOW INTO
WEDNESDAY.
UNDERCUT THE GUIDANCE FOR THE DAYTIME MAXIMUM TEMPERATURES GIVEN THE
CLOUD COVER...PRECIPITATION...NORTHWESTERLY FLOW...AND COLD POOL
ALOFT. WITH THAT BEING SAID...GIVEN THE TIME OF YEAR...BEST CHANCE
FOR SNOW ACCUMULATIONS WILL BE DURING THE OVERNIGHT HOURS. HAVE
DAYTIME TEMPERATURES CLIMBING ABOVE FREEZING IN MOST
CASES...ALTHOUGH THE MOUNTAINS WILL HOVER AROUND FREEZING OR STAY
BELOW IN THE CASE OF THE HIGHER ELEVATIONS OF THE NORTHEAST
MOUNTAINS. SO...EXPECT SOME MELTING DURING THE DAY...WITH SUN ANGLE
AND LONGER DAYS THAN NIGHTS ALSO CONTRIBUTING TO THIS EQUATION.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
USED THE ECMWF ENSEMBLE MEAN THROUGH THE PERIOD. SOME UPSLOPE SNOW
SHOWERS REMAIN A POSSIBILITY TUESDAY NIGHT INTO EARLY THURSDAY. HIGH
PRESSURE THEN BUILDS IN FOR THURSDAY NIGHT AND FRIDAY. A LOW
CONFIDENCE SYSTEM THEN SLIDES SOUTH OF THE AREA FRIDAY NIGHT AND
SATURDAY...CAUSING SOME SMALL POPS OVER OUR FORECAST AREA.
&&
.AVIATION /17Z SUNDAY THROUGH THURSDAY/...
AN APPROACHING LOW PRESSURE SYSTEM IS PUSHING MOISTURE ACROSS THE
REGION. WARM AIR HAS SURGED UP THE WESTERN SLOPES OF THE MOUNTAINS.
THIS WILL CAUSE RAIN WEST OF THE SPINE...AND SNOW TO THE EAST.
CEILINGS WILL GRADUALLY COLLAPSE AS THE RAIN MOVES IN...ALTHOUGH A
SOUTHEAST DOWNSLOPE WIND ALONG THE WESTERN SLOPES WILL PROVIDE A
SMALL AREA OF HIGHER CEILINGS. COLDER AIR WILL WRAP AROUND THE LOW
AND MOVE IN TONIGHT...CHANGING THE RAIN TO SNOW AND CREATING A LOW
STRATUS DECK. SNOW SHOWERS CAN BE EXPECTED ON MONDAY WITH THE
STRATUS DECK CONTINUING.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY...
FORECAST CONFIDENCE...MEDIUM.
ALTERNATE SCENARIOS: CEILINGS WITH THIS SYSTEM COULD VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY L L L L L L L L L M M M
HTS CONSISTENCY M H H H H H H H H M H H
BKW CONSISTENCY M M M M M M M M M M M M
EKN CONSISTENCY L L M M M M M M L L M M
PKB CONSISTENCY H H M M M L M M M M M M
CKB CONSISTENCY H H M M M M M M M M M M
AFTER 18Z MONDAY...
IFR CONDITIONS POSSIBLE IN SNOW SHOWERS MONDAY AFTERNOON AND TUESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER WEATHER ADVISORY UNTIL 11 AM EDT MONDAY FOR WVZ010-011-
020-031-032-039-040.
WINTER STORM WARNING UNTIL 2 PM EDT TUESDAY FOR WVZ038-046-047.
OH...WINTER WEATHER ADVISORY UNTIL 11 AM EDT MONDAY FOR OHZ066-067-
075-076-084.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JMV/26
NEAR TERM...JMV
SHORT TERM...26
LONG TERM...RPY
AVIATION...RPY
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
639 AM EDT SUN MAR 24 2013
.SYNOPSIS...
BELOW NORMAL TEMPERATURES THROUGH NEXT WEEK. WINTER STORM AFFECTS
THE AREA SUNDAY AND LATE MONDAY...BRINGING MAINLY RAIN SUNDAY...
CHANGING TO ALL SNOW MONDAY NIGHT. UPSLOPE SNOW EVENT FOLLOWS.
&&
.NEAR TERM /THROUGH TONIGHT/...
630 AM UPDATE...FRESHENED UP GRIDS A BIT...BUT NO SIGNIFICANT
CHANGES.
PREVIOUS DISCUSSION...
WHAT A COMPLEX SYSTEM. ON THE POSITIVE SIDE...MODELS AGREE VERY WELL
ON THE MASS AND QPF FIELDS OF THE SYSTEM AFFECTING US THIS PERIOD.
PARENT SURFACE LOW LIFTS NORTHEAST INTO SOUTHERN OHIO AHEAD OF A
DEVELOPING STRONG UPPER LOW OVER THE MID MISSISSIPPI VALLEY...THEN
REDEVELOPS LATER TONIGHT JUST OFF THE MID ATLANTIC COAST AS THE
APPROACHING UPPER SYSTEM TAPS INTO THE GULF STREAM WATERS. LOOKS LIKE
ONE SLUG OF QPF THIS AFTERNOON WITH A LEAD SHORT WAVE AND ANOTHER
TONIGHT WITH THE UPPER LOW ITSELF. HOWEVER...THE THERMAL FIELDS WITH
THE SYSTEM DO NOT AGREE WELL...AND THIS IS CRITICAL TO THE TYPE OF
PRECIP IN A QPF REGIME OF BETWEEN HALF AN INCH AND AN INCH.
NORMALLY...I REPEAT NORMALLY...WITH THE TRACK OF THE PARENT SURFACE
LOW WE WOULD EXPECT A BRIEF PERIOD OF WINTRY MIX TO RAIN IN THE
LOWLANDS AS THE TYPICAL WARM WEDGE IN LOW LEVEL SOUTHEASTERLY FLOW
SURGES AHEAD OF THE LOW. WE WOULD KEEP A WINTRY TYPE PRECIP REGIME
IN THE NORTHERN MOUNTAINS WITH THE TYPICAL UPSLOPE AND COLD AIR
DAMMING. WE WOULD THEN SEE A TRANSITION BACK TO SNOW LATER TONIGHT
AS COLDER AIR WORKS IN ALOFT.
HOWEVER...THE TRACK OF THE UPPER SYSTEM IS EAST RIGHT ACROSS OUR
AREA. THIS PREVENTS THE WARM WEDGE FROM GETTING TOO FAR NORTH THIS
AFTERNOON AS THE HEAVIER PRECIP ARRIVES. THE NAM AND RUC ARE THE
WARM OUTLIER FOR THE WARM WEDGE...WHILE THE GFS AND EURO ARE COLDER.
THIS COLDER SCENARIO APPEARS TO BE DUE TO STRONG UPPER DYNAMICS AND
WET BULBING WHIT THE PRECIP. EVEN THE SREF SHOWS THIS.
AM GOING WITH THE COOLER SCENARIO. YES...THE MAV/LAMP TEMP GUIDANCE
CURIOUSLY SHOW HIGHS IN THE 40S FOR MUCH OF THE LOWLANDS TODAY...BUT
THIS IS DISCOUNTED BY THE GUIDANCE NOT SEEMING TO ACCOUNT FOR WET
BULB COOLING. SO WILL ACTUALLY USE THE COOLER NAM SURFACE TEMPS BUT
THE GFS/EURO AND SREF COOLER TEMPS ALOFT.
ALL THIS PANS OUT TO TEMPS TODAY REMAINING IN THE 30S ACROSS THE
MOST OF THE LOWLANDS...WHILE BELOW FREEZING TEMPS OCCUR IN THE
NORTHERN MOUNTAINS. THIS WILL BE COLD ENOUGH FOR ALL SNOW NORTHERN
MOUNTAINS...SNOW WITH MIXED RAIN AND SLEET ACROSS THE FAR
NORTH...AND BRIEF WINTRY MIX TO RAIN ELSEWHERE. WITH THE AMOUNT OF
QPF...COULD BE HEAVY WET SNOW ACROSS THE FAR NORTH. THUS...ISSUED A
WINTER WEATHER ADVISORY FOR THE AREA LATER THIS AFTERNOON AND
ESPECIALLY TONIGHT WITH THE SECOND QPF SLUG. WINTER STORM WARNING
REMAINS IN EFFECT FOR THE NORTHERN MOUNTAINS.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
LOW PRESSURE SYSTEM EXITS TO THE EAST...ONLY TO HAVE CYCLONIC FLOW
REINFORCED BY A SECONDARY TROUGH SWINGING THROUGH THE TENNESSEE
VALLEY INTO THE MID ATLANTIC. IN THE LOWER LEVELS...FLOW WILL TURN
AROUND TO THE NORTHWEST THAT WILL EVENTUALLY TAP INTO SOME GREAT
LAKES MOISTURE. COLD POOL ALOFT WILL SETTLE INTO THE AREA...AND WILL
NOT RELINQUISH ITS GRIP ALL THE WAY INTO MID WEEK...WITH 850MB
TEMPERATURES VARYING FROM -7C TO -10C. IN THE END...THIS RESULTS IN
POPS FOR THE BULK OF THE SHORT TERM FORECAST ENHANCED BY THE
AFOREMENTIONED SECONDARY TROUGH AXIS MONDAY EVENING INTO
TUESDAY...AND THEN THE CONVECTIVE NATURE OF THE NORTHWEST FLOW INTO
WEDNESDAY.
UNDERCUT THE GUIDANCE FOR THE DAYTIME MAXIMUM TEMPERATURES GIVEN THE
CLOUD COVER...PRECIPITATION...NORTHWESTERLY FLOW...AND COLD POOL
ALOFT. WITH THAT BEING SAID...GIVEN THE TIME OF YEAR...BEST CHANCE
FOR SNOW ACCUMULATIONS WILL BE DURING THE OVERNIGHT HOURS. HAVE
DAYTIME TEMPERATURES CLIMBING ABOVE FREEZING IN MOST
CASES...ALTHOUGH THE MOUNTAINS WILL HOVER AROUND FREEZING OR STAY
BELOW IN THE CASE OF THE HIGHER ELEVATIONS OF THE NORTHEAST
MOUNTAINS. SO...EXPECT SOME MELTING DURING THE DAY...WITH SUN ANGLE
AND LONGER DAYS THAN NIGHTS ALSO CONTRIBUTING TO THIS EQUATION.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
USED THE ECMWF ENSEMBLE MEAN THROUGH THE PERIOD. SOME UPSLOPE SNOW
SHOWERS REMAIN A POSSIBILITY TUESDAY NIGHT INTO EARLY THURSDAY. HIGH
PRESSURE THEN BUILDS IN FOR THURSDAY NIGHT AND FRIDAY. A LOW
CONFIDENCE SYSTEM THEN SLIDES SOUTH OF THE AREA FRIDAY NIGHT AND
SATURDAY...CAUSING SOME SMALL POPS OVER OUR FORECAST AREA.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
12Z SUNDAY THRU 12Z MONDAY...
VFR THRU 12Z WITH INCREASE IN MID/HI CLDS OVERNIGHT.
CIGS WITH ASSOC PRECIP WILL BE RAPIDLY PUSHING NORTHEASTWARD ACROSS
THE AREA...WITH MUCH OF THE AREA FALLING THROUGH MVFR CIGS AND INTO
IFR CIGS AFTER PRECIP BEGINS. A MIX OF RA/SN FOR KHTS-KCRW-KBKW 15
TO 18Z WITH SOME IFR VSBY WHERE PCPN STAYS MAINLY SN. A SWITCH TO RA
IN AFTN CENTRAL AND SOUTHERN LOW LANDS WITH PERHAPS SOME IMPROVEMENT
IN CIGS INTO MVFR. AS PCPN PUSHES N...IFR CONDITIONS IN MAINLY SN
DEVELOP AFTER 18Z FOR N TAF SITES...ESPECIALLY NORTHERN AND CENTRAL
MOUNTAINS.
AFTER 00Z...MAINLY IFR. WINTRY PRECIP CONTINUES NORTHERN AND
CENTRAL MOUNTAINS...WHILE MIXED PRECIP CHANGES TO SNOW BY 06Z
ELSEWHERE.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY...
FORECAST CONFIDENCE...MED TO HIGH.
ALTERNATE SCENARIOS: TIMING OF SUB-VFR CIGS AND ONSET OF PRECIP MAY
VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18
CRW CONSISTENCY H H H H M M L M M M M M
HTS CONSISTENCY H H H H H H L M M M H L
BKW CONSISTENCY H H H L M M M M M M M M
EKN CONSISTENCY H H H H H H L L L L M M
PKB CONSISTENCY H H H H H H H H H M M M
CKB CONSISTENCY H H H H H H H H L L M M
AFTER 12Z MONDAY...
IFR CONDITIONS POSSIBLE IN SNOW SHOWERS MONDAY AND TUESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 11 AM EDT
MONDAY FOR WVZ010-011-020-031-032-039-040.
WINTER STORM WARNING FROM NOON TODAY TO 2 PM EDT TUESDAY FOR
WVZ038-046-047.
OH...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 11 AM EDT
MONDAY FOR OHZ066-067-075-076-084.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JMV/26
NEAR TERM...JMV
SHORT TERM...26
LONG TERM...RPY
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
512 AM EDT SUN MAR 24 2013
.SYNOPSIS...
BELOW NORMAL TEMPERATURES THROUGH NEXT WEEK. WINTER STORM AFFECTS
THE AREA SUNDAY AND LATE MONDAY...BRINGING MAINLY RAIN SUNDAY...
CHANGING TO ALL SNOW MONDAY NIGHT. UPSLOPE SNOW EVENT FOLLOWS.
&&
.NEAR TERM /THROUGH TONIGHT/...
WHAT A COMPLEX SYSTEM. ON THE POSITIVE SIDE...MODELS AGREE VERY WELL
ON THE MASS AND QPF FIELDS OF THE SYSTEM AFFECTING US THIS PERIOD.
PARENT SURFACE LOW LIFTS NORTHEAST INTO SOUTHERN OHIO AHEAD OF A
DEVELOPING STRONG UPPER LOW OVER THE MID MISSISSIPPI VALLEY...THEN
REDEVELOPS LATER TONIGHT JUST OFF THE MID ATLANTIC COAST AS THE
APPROACHING UPPER SYSTEM TAPS INTO THE GULF STREAM WATERS. LOOKS LIKE
ONE SLUG OF QPF THIS AFTERNOON WITH A LEAD SHORT WAVE AND ANOTHER
TONIGHT WITH THE UPPER LOW ITSELF. HOWEVER...THE THERMAL FIELDS WITH
THE SYSTEM DO NOT AGREE WELL...AND THIS IS CRITICAL TO THE TYPE OF
PRECIP IN A QPF REGIME OF BETWEEN HALF AN INCH AND AN INCH.
NORMALLY...I REPEAT NORMALLY...WITH THE TRACK OF THE PARENT SURFACE
LOW WE WOULD EXPECT A BRIEF PERIOD OF WINTRY MIX TO RAIN IN THE
LOWLANDS AS THE TYPICAL WARM WEDGE IN LOW LEVEL SOUTHEASTERLY FLOW
SURGES AHEAD OF THE LOW. WE WOULD KEEP A WINTRY TYPE PRECIP REGIME
IN THE NORTHERN MOUNTAINS WITH THE TYPICAL UPSLOPE AND COLD AIR
DAMMING. WE WOULD THEN SEE A TRANSITION BACK TO SNOW LATER TONIGHT
AS COLDER AIR WORKS IN ALOFT.
HOWEVER...THE TRACK OF THE UPPER SYSTEM IS EAST RIGHT ACROSS OUR
AREA. THIS PREVENTS THE WARM WEDGE FROM GETTING TOO FAR NORTH THIS
AFTERNOON AS THE HEAVIER PRECIP ARRIVES. THE NAM AND RUC ARE THE
WARM OUTLIER FOR THE WARM WEDGE...WHILE THE GFS AND EURO ARE COLDER.
THIS COLDER SCENARIO APPEARS TO BE DUE TO STRONG UPPER DYNAMICS AND
WET BULBING WHIT THE PRECIP. EVEN THE SREF SHOWS THIS.
AM GOING WITH THE COOLER SCENARIO. YES...THE MAV/LAMP TEMP GUIDANCE
CURIOUSLY SHOW HIGHS IN THE 40S FOR MUCH OF THE LOWLANDS TODAY...BUT
THIS IS DISCOUNTED BY THE GUIDANCE NOT SEEMING TO ACCOUNT FOR WET
BULB COOLING. SO WILL ACTUALLY USE THE COOLER NAM SURFACE TEMPS BUT
THE GFS/EURO AND SREF COOLER TEMPS ALOFT.
ALL THIS PANS OUT TO TEMPS TODAY REMAINING IN THE 30S ACROSS THE
MOST OF THE LOWLANDS...WHILE BELOW FREEZING TEMPS OCCUR IN THE
NORTHERN MOUNTAINS. THIS WILL BE COLD ENOUGH FOR ALL SNOW NORTHERN
MOUNTAINS...SNOW WITH MIXED RAIN AND SLEET ACROSS THE FAR
NORTH...AND BRIEF WINTRY MIX TO RAIN ELSEWHERE. WITH THE AMOUNT OF
QPF...COULD BE HEAVY WET SNOW ACROSS THE FAR NORTH. THUS...ISSUED A
WINTER WEATHER ADVISORY FOR THE AREA LATER THIS AFTERNOON AND
ESPECIALLY TONIGHT WITH THE SECOND QPF SLUG. WINTER STORM WARNING
REMAINS IN EFFECT FOR THE NORTHERN MOUNTAINS.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
LOW PRESSURE SYSTEM EXITS TO THE EAST...ONLY TO HAVE CYCLONIC FLOW
REINFORCED BY A SECONDARY TROUGH SWINGING THROUGH THE TENNESSEE
VALLEY INTO THE MID ATLANTIC. IN THE LOWER LEVELS...FLOW WILL TURN
AROUND TO THE NORTHWEST THAT WILL EVENTUALLY TAP INTO SOME GREAT
LAKES MOISTURE. COLD POOL ALOFT WILL SETTLE INTO THE AREA...AND WILL
NOT RELINQUISH ITS GRIP ALL THE WAY INTO MID WEEK...WITH 850MB
TEMPERATURES VARYING FROM -7C TO -10C. IN THE END...THIS RESULTS IN
POPS FOR THE BULK OF THE SHORT TERM FORECAST ENHANCED BY THE
AFOREMENTIONED SECONDARY TROUGH AXIS MONDAY EVENING INTO
TUESDAY...AND THEN THE CONVECTIVE NATURE OF THE NORTHWEST FLOW INTO
WEDNESDAY.
UNDERCUT THE GUIDANCE FOR THE DAYTIME MAXIMUM TEMPERATURES GIVEN THE
CLOUD COVER...PRECIPITATION...NORTHWESTERLY FLOW...AND COLD POOL
ALOFT. WITH THAT BEING SAID...GIVEN THE TIME OF YEAR...BEST CHANCE
FOR SNOW ACCUMULATIONS WILL BE DURING THE OVERNIGHT HOURS. HAVE
DAYTIME TEMPERATURES CLIMBING ABOVE FREEZING IN MOST
CASES...ALTHOUGH THE MOUNTAINS WILL HOVER AROUND FREEZING OR STAY
BELOW IN THE CASE OF THE HIGHER ELEVATIONS OF THE NORTHEAST
MOUNTAINS. SO...EXPECT SOME MELTING DURING THE DAY...WITH SUN ANGLE
AND LONGER DAYS THAN NIGHTS ALSO CONTRIBUTING TO THIS EQUATION.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
USED THE ECMWF ENSEMBLE MEAN THROUGH THE PERIOD. SOME UPSLOPE SNOW
SHOWERS REMAIN A POSSIBILITY TUESDAY NIGHT INTO EARLY THURSDAY. HIGH
PRESSURE THEN BUILDS IN FOR THURSDAY NIGHT AND FRIDAY. A LOW
CONFIDENCE SYSTEM THEN SLIDES SOUTH OF THE AREA FRIDAY NIGHT AND
SATURDAY...CAUSING SOME SMALL POPS OVER OUR FORECAST AREA.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
06Z SUNDAY THRU 06Z MONDAY...
VFR THRU 12Z WITH INCREASE IN MID/HI CLDS OVERNIGHT.
AFTER 12Z CIGS WITH ASSOC PRECIP WILL BE RAPIDLY PUSHING
NORTHEASTWARD ACROSS THE AREA...WITH MUCH OF THE AREA FALLING
THROUGH MVFR CIGS AND INTO IFR CIGS AFTER PRECIP BEGINS. A MIX OF
RA/SN FOR KHTS-KCRW-KBKW 15 TO 18Z WITH SOME IFR VSBY WHERE PCPN
STAYS MAINLY SN. A SWITCH TO RA IN AFTN CENTRAL AND SOUTHERN LOW
LANDS WITH PERHAPS SOME IMPROVEMENT IN CIGS INTO MVFR. AS PCPN
PUSHES N...IFR CONDITIONS IN MAINLY SN DEVELOP AFTER 18Z FOR N TAF
SITES...ESPECIALLY NORTHERN AND CENTRAL MOUNTAINS.
AFTER 00Z...IFR TO MVFR. WINTRY PRECIP CONTINUES NORTHERN AND
CENTRAL MOUNTAINS...WHILE MIXED PRECIP CHANGES TO SNOW BY 06Z
ELSEWHERE.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z MONDAY...
FORECAST CONFIDENCE...MED TO HIGH.
ALTERNATE SCENARIOS: TIMING OF SUB-VFR CIGS AND ONSET OF PRECIP MAY
VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE SUN 03/24/13
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15
CRW CONSISTENCY H H H H H H H M M H H H
HTS CONSISTENCY H H H H H H H H H M H H
BKW CONSISTENCY H H H H H H L M M M M M
EKN CONSISTENCY H H H H H H H H H H L L
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 06Z MONDAY...
IFR CONDITIONS POSSIBLE IN RAIN AND WINTRY MIX INTO SUNDAY NIGHT
AND THEN MAINLY SNOW EARLY MONDAY MORNING THROUGH MONDAY NIGHT.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 11 AM EDT
MONDAY FOR WVZ010-011-020-031-032-039-040.
WINTER STORM WARNING FROM NOON TODAY TO 2 PM EDT TUESDAY FOR
WVZ038-046-047.
OH...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 11 AM EDT
MONDAY FOR OHZ066-067-075-076-084.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JMV/26
NEAR TERM...JMV
SHORT TERM...26
LONG TERM...RPY
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1051 PM CDT MON MAR 25 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 242 PM CDT MON MAR 25 2013
SURFACE RIDGE OVER THE HIGH PLAINS WILL SHIFT EASTWARD ACROSS THE
REGION TONIGHT. SUBSIDENCE WILL CONTINUE TO INCREASE...WHICH WILL
ALLOW THE STRATUS BLANKETING MUCH OF THE FORECAST AREA THIS
AFTERNOON TO SHIFT EASTWARD AND GRADUALLY ERODE OVERNIGHT. THE
BREEZY NORTH NORTHWEST WINDS WILL ALSO DECREASE QUICKLY WITH
SUNSET...BECOMING LIGHT AND VARIABLE LATE TONIGHT. WITH CLEARING
SKIES AND LIGHT WINDS...TEMPERATURES WILL BE QUITE COLD
OVERNIGHT...AND WILL LIKELY APPROACH ZERO IN OUR EXTREME NORTH WITH
THE LOW TEENS IN THE SOUTH. COULD SEE SOME PATCHY FOG DEVELOP LATE
TONIGHT...MAINLY ALONG AND WEST OF I-29 WHERE THE LIGHT WINDS AND
CLEARING WILL BE MOST PRONOUNCED.
LIGHT AND VARIABLE WINDS TUESDAY WILL GRADUALLY TURN SOUTHEASTERLY
ACROSS THE FORECAST AREA...BECOMING SOMEWHAT BREEZY IN SOUTH CENTRAL
SOUTH DAKOTA BY AFTERNOON. SKIES WILL BE MOSTLY SUNNY AND
TEMPERATURES WILL MODERATE QUITE A BIT. MUCH OF THE FORECAST AREA
WILL BE NEAR OR ABOVE FREEZING...WITH HIGHS EVEN REACHING THE LOW
40S IN SOUTH CENTRAL.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 242 PM CDT MON MAR 25 2013
EXTENDED PERIOD QUIET FOR THE MOST PART WITH UPPER RIDGE SLOWLY
AMPLIFYING ACROSS THE ROCKIES THROUGH THE WEEK. CONSEQUENTLY...THE
H85 TEMPERATURES SLOWLY RISE TO ABOVE 0C ACROSS THE ENTIRE CWA BY
00Z SATURDAY. HOWEVER...WILL NOT SEE FULL POTENTIAL OF THESE WARMER
TEMPERATURES AS LOW LEVEL FLOW REMAINS WEAK AND OUT OF THE
EAST-SOUTHEAST...WHICH IS NOT GOOD FOR MIXING. NEVERTHELESS
TEMPERATURES WILL STILL WARM AND FEEL MORE AND MORE SPRING-LIKE
THROUGH THE WEEK.
FRIDAY NIGHT INTO SATURDAY...SOUTHERLY SFC WINDS FINALLY INCREASE
IN RESPONSE TO DEVELOPING LOW LEVEL JET AHEAD OF AN APPROACHING
SURFACE TROUGH. THIS TROUGH IS A REFLECTION OF ELONGATED SHORT
WAVE ROUNDING BASE OF MAIN UPPER LOW OVER NORTHERN CANADA. WITH
WINDS INCREASING AND H85 TEMPS CLIMBING TO +4 TO 8C ACROSS THE
CWA...SATURDAY LOOKS TO BE THE WARMEST DAY OF THE FORECAST ATTM.
WILL ALSO SEE A CHANCE FOR SOME RAIN WITH THIS TROUGH PASSAGE ON
SATURDAY. SOME FAIRLY GOOD MOISTURE RETURN ON THE 12Z GFS
/RELATIVE TO THIS YEAR OF COURSE/ SHOWING UP ALONG AND JUST AHEAD
OF THE TROUGH IN SOUTH CENTRAL AROUND AND INCLUDING KSUX BY
SATURDAY 18Z WITH NEAR 50F SFC DEWPOINTS AND A COUPLE HUNDRED J/KG
OF SBCAPE EXTENDING NORTH INTO THE AREA. WILL NEED TO MONITOR
FUTURE RUNS FOR CONSISTENCY AND POSSIBLY ADD A MENTION OF THUNDER
FOR THE SOUTH-CENTRAL CWA...AROUND KSUX FOR SATURDAY.
12Z GFS AND 00Z ECMWF SHOWING SOME BIG DIFFERENCES IN STRENGTH AND
PLACEMENT OF BACK DOOR COLD FRONT FOR THE LATTER PORTION OF THE
WEEKEND AND INTO NEXT MONDAY. THE DIFFERENCES MAINLY STEM FROM THE
UPPER LOW SINKING SOUTH /ECMWF/ OR SOUTHEAST /GFS/. HENCE THE 00Z
ECMWF IS MUCH COLDER FOR TEMPERATURES MONDAY. HOWEVER...ECMWF HAS
BEEN VERY INCONSISTENT RUN-TO-RUN WITH THIS COLD AIR AND NEW 12Z
ECMWF SHOWING A BIT WARMER TEMPERATURES NOW...SO WILL NOT MAKE ANY
BIG ADJUSTMENTS TO FORECAST ATTM.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1042 PM CDT MON MAR 25 2013
DESPITE NAM GUIDANCE SUGGESTING FAIRLY SUBSTANTIAL FOG THREAT FOR
KHON...HAVE KEPT MENTION OUT OF FORECAST WITH BOTH HRRR AND RAP
CONTINUING TO SUGGEST RADIATIONAL FOG WOULD REMAIN ACROSS
NORTHEAST PORTIONS OF SOUTH DAKOTA. WITH SCATTERED CLOUDS ACROSS
THE AREA...RADIATIONAL COOLING WILL BE RETARDED...THUS LIMITING
FOG POTENTIAL. LIGHT WINDS AND MOSTLY CLEAR SKIES WILL PREVAIL ON
TUESDAY WITH LIGHT EASTERLY FLOW DEVELOPING TUESDAY EVENING.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...AEB
AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
635 PM CDT MON MAR 25 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 242 PM CDT MON MAR 25 2013
SURFACE RIDGE OVER THE HIGH PLAINS WILL SHIFT EASTWARD ACROSS THE
REGION TONIGHT. SUBSIDENCE WILL CONTINUE TO INCREASE...WHICH WILL
ALLOW THE STRATUS BLANKETING MUCH OF THE FORECAST AREA THIS
AFTERNOON TO SHIFT EASTWARD AND GRADUALLY ERODE OVERNIGHT. THE
BREEZY NORTH NORTHWEST WINDS WILL ALSO DECREASE QUICKLY WITH
SUNSET...BECOMING LIGHT AND VARIABLE LATE TONIGHT. WITH CLEARING
SKIES AND LIGHT WINDS...TEMPERATURES WILL BE QUITE COLD
OVERNIGHT...AND WILL LIKELY APPROACH ZERO IN OUR EXTREME NORTH WITH
THE LOW TEENS IN THE SOUTH. COULD SEE SOME PATCHY FOG DEVELOP LATE
TONIGHT...MAINLY ALONG AND WEST OF I-29 WHERE THE LIGHT WINDS AND
CLEARING WILL BE MOST PRONOUNCED.
LIGHT AND VARIABLE WINDS TUESDAY WILL GRADUALLY TURN SOUTHEASTERLY
ACROSS THE FORECAST AREA...BECOMING SOMEWHAT BREEZY IN SOUTH CENTRAL
SOUTH DAKOTA BY AFTERNOON. SKIES WILL BE MOSTLY SUNNY AND
TEMPERATURES WILL MODERATE QUITE A BIT. MUCH OF THE FORECAST AREA
WILL BE NEAR OR ABOVE FREEZING...WITH HIGHS EVEN REACHING THE LOW
40S IN SOUTH CENTRAL.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 242 PM CDT MON MAR 25 2013
EXTENDED PERIOD QUIET FOR THE MOST PART WITH UPPER RIDGE SLOWLY
AMPLIFYING ACROSS THE ROCKIES THROUGH THE WEEK. CONSEQUENTLY...THE
H85 TEMPERATURES SLOWLY RISE TO ABOVE 0C ACROSS THE ENTIRE CWA BY
00Z SATURDAY. HOWEVER...WILL NOT SEE FULL POTENTIAL OF THESE WARMER
TEMPERATURES AS LOW LEVEL FLOW REMAINS WEAK AND OUT OF THE
EAST-SOUTHEAST...WHICH IS NOT GOOD FOR MIXING. NEVERTHELESS
TEMPERATURES WILL STILL WARM AND FEEL MORE AND MORE SPRING-LIKE
THROUGH THE WEEK.
FRIDAY NIGHT INTO SATURDAY...SOUTHERLY SFC WINDS FINALLY INCREASE
IN RESPONSE TO DEVELOPING LOW LEVEL JET AHEAD OF AN APPROACHING
SURFACE TROUGH. THIS TROUGH IS A REFLECTION OF ELONGATED SHORT
WAVE ROUNDING BASE OF MAIN UPPER LOW OVER NORTHERN CANADA. WITH
WINDS INCREASING AND H85 TEMPS CLIMBING TO +4 TO 8C ACROSS THE
CWA...SATURDAY LOOKS TO BE THE WARMEST DAY OF THE FORECAST ATTM.
WILL ALSO SEE A CHANCE FOR SOME RAIN WITH THIS TROUGH PASSAGE ON
SATURDAY. SOME FAIRLY GOOD MOISTURE RETURN ON THE 12Z GFS
/RELATIVE TO THIS YEAR OF COURSE/ SHOWING UP ALONG AND JUST AHEAD
OF THE TROUGH IN SOUTH CENTRAL AROUND AND INCLUDING KSUX BY
SATURDAY 18Z WITH NEAR 50F SFC DEWPOINTS AND A COUPLE HUNDRED J/KG
OF SBCAPE EXTENDING NORTH INTO THE AREA. WILL NEED TO MONITOR
FUTURE RUNS FOR CONSISTENCY AND POSSIBLY ADD A MENTION OF THUNDER
FOR THE SOUTH-CENTRAL CWA...AROUND KSUX FOR SATURDAY.
12Z GFS AND 00Z ECMWF SHOWING SOME BIG DIFFERENCES IN STRENGTH AND
PLACEMENT OF BACK DOOR COLD FRONT FOR THE LATTER PORTION OF THE
WEEKEND AND INTO NEXT MONDAY. THE DIFFERENCES MAINLY STEM FROM THE
UPPER LOW SINKING SOUTH /ECMWF/ OR SOUTHEAST /GFS/. HENCE THE 00Z
ECMWF IS MUCH COLDER FOR TEMPERATURES MONDAY. HOWEVER...ECMWF HAS
BEEN VERY INCONSISTENT RUN-TO-RUN WITH THIS COLD AIR AND NEW 12Z
ECMWF SHOWING A BIT WARMER TEMPERATURES NOW...SO WILL NOT MAKE ANY
BIG ADJUSTMENTS TO FORECAST ATTM.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 629 PM CDT MON MAR 25 2013
VFR STRATUS ACROSS THE AREA WILL GRADUALLY MELT AWAY THIS EVENING
LEADING TO CLEAR SKIES. WITH LIGHT WINDS ACROSS THE AREA...WILL
HAVE GREAT RADIATIVE CONDITIONS AND THE POTENTIAL EXISTS FOR
RADIATIVE FOG DEVELOPING. BOTH THE RAP AND THE HRRR SUGGEST BEST
POTENTIAL WILL BE ACROSS THE NORTHERN CWA ALONG THE HIGHWAY 14
CORRIDOR. HAVE KEPT FOG MENTION IN KHON TAF...THOUGH MODELS WOULD
SUGGEST FOG WOULD MAINLY BE FOCUSED JUST TO THE EAST.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...AEB
AVIATION...
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
1002 AM EDT SUN MAR 24 2013
.DISCUSSION...INITIAL ROUND OF SHOWERS HAS MOVED THROUGH MOST OF THE
FORECAST AREA THIS MORNING. DRY SLOT NOW MOVING IN WILL REQUIRE
LOWERING RAIN CHANCES FOR AT LEAST A FEW HOURS. LATEST RUC MODEL
SPREADS MORE SHOWERS OUR WAY BEFORE HEAVIER SHOWERS AND ISOLATED
THUNDERSTORMS OCCUR WITH THE FRONTAL BOUNDARY BY MID TO LATE
AFTERNOON. FREEZING LEVEL QUITE LOW ALREADY FOR LATE MARCH AND WILL
LOWER EVEN MORE AS COLDER AIR APPROACHES THIS AFTERNOON AND EVENING.
SEVERE THREAT SHOULD BE MAINLY LARGE HAIL WITH STRONGEST STORMS THAT
DEVELOP.
WINTRY WEATHER PARTS OF FORECAST LOOK ON TRACK FOR NOW. SYNOPTIC
SCALE FORCING IS GONE AFTER MONDAY MORNING...LEAVING A PROLONGED
PERIOD OF NW FLOW WITH UPSLOPE LOW LEVEL FORCING. MOISTURE LOOKS
DEEP AND LAPSE RATES ARE QUITE STEEP ON MONDAY AFTERNOON...WITH EVEN
MORE INSTABILITY (CAPES OF AROUND 100 J/KG) NOTED FOR TUESDAY
DAYTIME. OUTSIDE OF THE WATCH AREA...THINK BANDS OF SNOW SHOWERS
WILL PROVIDE A HIT OR MISS PATTERN OF LIGHT SNOW ACCUMULATIONS...AND
GENERALLY MEETING ADVISORY CRITERIA OR LESS. WILL DEFER ANY CHANGES
BEYOND TODAY TO THE AFTERNOON PACKAGE.
UPDATED GRIDS AND PRODUCTS BY AROUND 11 AM EDT.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 61 36 43 32 44 / 100 50 20 10 30
KNOXVILLE AIRPORT, TN 57 36 42 31 42 / 100 60 40 40 30
OAK RIDGE, TN 57 36 42 32 41 / 100 60 40 40 30
TRI CITIES AIRPORT, TN 52 32 38 31 39 / 100 80 60 70 40
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR THE FOLLOWING ZONES: BLOUNT SMOKY MOUNTAINS...COCKE
SMOKY MOUNTAINS...JOHNSON...SEVIER SMOKY MOUNTAINS...
SOUTHEAST CARTER...SOUTHEAST GREENE...UNICOI.
VA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON
FOR THE FOLLOWING ZONES: LEE...RUSSELL...SCOTT...
WASHINGTON...WISE.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1146 PM CDT SAT MAR 23 2013
.UPDATE...ADDED AVIATION SECTION FOR 06 TAF`S.
&&
.AVIATION...BNA/CKV/CSV...TRICKY WX SITUATION SHAPING UP DURING
THE NEXT 18 HRS OR SO AS MOISTURE GRADUALLY SPREADS ACROSS
MIDDLE TENNESSEE AHEAD OF A STRONG LOW PRESSURE SYSTEM. EXPECTING
MAINLY LIGHT RAIN WITH LOW CIGS DEVELOPING OVERNIGHT AS THE
SURFACE LOW RACES NEWD TOWARD MIDDLE TENNESSEE. FORECAST LOW TRACK
ACTUALLY BISECTS THE MID STATE ON SUNDAY WHILE DRAGGING A COLD
FRONT ACROSS THE AREA DURING THE AFTERNOON. DEEPEST MOISTURE
APPEARS TO PULL OUT AHEAD OF THE FRONT, BUT, GIVEN THE ENHANCED
FORCING BY THE LOW ITSELF, THERE MAY BE ENOUGH LEFTOVER LOW-LEVEL
MOISTURE TO KICK OFF A LINE OF CONVECTION ALONG THE FRONT ITSELF.
ALSO LOOK FOR WINDS TO INCREASE DRAMATICALLY DURING THE AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 929 PM CDT SAT MAR 23 2013/
MESOSCALE UPDATE...
AT 915PM...RADAR INDICATED AREAS OF MODERATE RAIN ENTERING
SOUTHERN MIDDLE TN. 00Z SOUNDING ANALYSIS DOES SHOW A CONSIDERABLE
INVERSION AT THE 800 MB LEVEL WITH STEEP LAPSE RATES ABOVE THE
INVERSION. SHORT TERM MODELS VARY ON DEPICTING HOW TONIGHTS
ACTIVITY WILL EVOLVE.
THE NAM IS DEFINITELY THE MOST AGGRESSIVE WITH THUNDER
POSSIBILITIES...DEPICTING STRONG LOW TO MID LEVEL OMEGA FIELDS
DRAPED FROM WESTERN KY THROUGH NORTHEAST AL. THIS IN CONJUNTION
WITH AN INTENSIFYING LLJ OF 45-50 KTS OVER NORTHERN AL. STRONG
SPEED CONVERGENCE AT THE 850 MB LEVEL OVER SOUTH CENTRAL TN
APPEARS TO BE THE METHOD OF FORCING THAT COULD PRODUCE SOME STRONG
THUNDERSTORMS OVERNIGHT FOR AREAS IN THE SOUTHERN THIRD OF THE
CWA. SMALL HAIL AND SOME STRONG WINDS WOULD BE THE MAIN THREATS.
OTHER HI RESOLUTION MODELS...WHILE STILL BRINGING WIDESPREAD RAIN
THROUGH MIDDLE TN BY 08Z...ARE LESS ROBUST ON THE FORCING. WHILE
THE SFC LOW PASSES ACROSS CENTRAL AL...AND THE LLJ DOES
INTENSIFY...RUC/HRRR DEPICTS WEAKER
INSTABILITY...CONVERGENCE...AND BULK SHEAR. THUS RESULTING IN A
WIDESPREAD...AND HEAVY AT TIMES...RAIN EVENT.
IF STRONG STORMS WERE TO DEVELOP FOR MIDDLE TN...STILL BELIEVE THE
THREAT WOULD BE IN THE SOUTHERNMOST COUNTIES...BUT FOR NOW...FEEL
THE MODERATE TO HEAVY RAIN SCENARIO WITH SOME THUNDER POSSIBLE
WILL STILL BE VALID.
PREV DISCUSSION... /ISSUED 649 PM CDT SAT MAR 23 2013/
UPDATE...ADDED AVIATION SECTION FOR 00Z TAF`S.
AVIATION...BNA/CKV/CSV...CONDITIONS SLOWLY DETERIORATING ACROSS
MIDDLE TENNESSEE THIS EVENING AS A SURFACE LOW APPROACHES FROM
THE SW. LOOK FOR LIGHT RAIN DURING THE EVENING WITH CIGS
EVENTUALLY LOWERING BELOW 3 KFT. WINDS WILL REMAIN LIGHT
OVERNIGHT, EVEN AS SHOWERS INCREASE IN INTENSITY AND CIGS DROP TO
IFR. RUC SOUNDINGS SHOWING NO SURFACED-BASED OR ELEVATED
INSTABILITY, SO WILL LEAVE TS OUT OF THE TAF`S. EXPECT WINDS TO
SHIFT AROUND TO THE SW ON SUNDAY AND INCREASE DRAMATICALLY AS THE
LOW BISECTS THE MID STATE.
PREV DISCUSSION... /ISSUED 242 PM CDT SAT MAR 23 2013/
DISCUSSION...
SHOWERS AND A FEW THUNDERSTORMS HAVE SPREAD AS FAR EAST AS NORTH
MISSISSIPPI AND INTO THE FAR SOUTHWEST CORNER OF TENNESSEE AROUND
MEMPHIS. GULF COAST SYSTEM WILL WORK ALONG COAST TONIGHT WITH
INVERTED TROUGH EXTENDING UP INTO TENNESSEE THROUGH THE OVERNIGHT
AS LOW LIFTS NORTHWARD LATE NIGHT INTO NORTH ALABAMA BY 12Z
SUNDAY. IT LOOKS LIKE A PRETTY GOOD ROUND OF RAIN LIFTING NORTH
THROUGH ALABAMA AND INTO MIDDLE TENNESSEE AFTER MIDNIGHT. I EXPECT
TO HEAR A LITTLE THUNDER WITH GOOD DOWNPOURS WITH THIS IN THE LATE
NIGHT HOURS AS IT MOVES THROUGH THE AREA. SURFACE LOW LIFTS UP
INTO MIDDLE TENNESSEE DURING THE DAY SUNDAY SO AM EXPECTING MORE
RAIN WITH A FEW THUNDERSTORMS DURING THE DAY ON SUNDAY. SURFACE
LOW LIFTS OUT TO THE NORTHEAST AND INTO EASTERN KENTUCKY BY
MIDNIGHT SUNDAY NIGHT WHILE UNDERGOING CYCLOGENSIS WITH PRECIP
HANGING BACK OVER MIDDLE TENNESSEE AS A MIX OF RAIN AND SNOW
SUNDAY NIGHT AS TEMPS FALL INTO THE LOWER 30S MOST AREAS. ON
MONDAY PRECIP STILL LINGERING IN THE FORM OF A MIX OVER SOUTHWESTERLY
AREAS AND LIGHT SNOW NORTHEAST HALF WITH HIGHS MOSTLY IN THE UPPER
30S. MONDAY NIGHT LOOKS HAVE THE BEST CHANCE FOR SEEING A LITTLE
ACCUMULATION HERE IN THE MID STATE. I THINK WE COULD BE LOOKING AT
AN INCH IN FENTRESS AND CUMBERLAND COUNTIES WEST TOWARD PUTNAM
COUNTY AS RESIDUAL MOISTURE GETS SQUEEZED OUT WITH A LITTLE HELP
FROM OROGRAPHY. LOOKS LIKE TEMPS WILL BE BELOW NORMAL AT LEAST
THROUGH NEXT FRIDAY WITH HIGHS ON SATURDAY IN THE 60S WHICH IS
JUST ABOUT NORMAL FOR THIS TIME OF THE YEAR.
CLIMATE...TEMPS ARE AVERAGING NEARLY 4 DEGREES BELOW NORMAL SO FAR THIS
MARCH. WHAT A CONTRAST WITH MARCH OF 2012 WHICH WAS THE WARMEST MARCH
ON RECORD. RAINFALL HAS TOTALED 3.20 INCHES WHICH IS CLOSE TO NORMAL
THROUGH THE THIRD WEEK OF MARCH.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
ROSE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
221 PM CDT SUN MAR 24 2013
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
221 PM CDT SUN MAR 24 2013
SNOW COMES TO AN END THIS EVENING WITH DRY AND BELOW NORMAL
TEMPERATURES EXPECTED FOR THE EARLY HALF OF THE WEEK.
CURRENTLY...LIGHT SNOW IS FALLING ACROSS PORTIONS OF THE REGION AS
A PAIR OF CLOSED MID LEVEL LOWS TRACK NEAR THE REGION. THE MORE
POTENT OF THESE LOWS IS MOVING INTO SOUTHERN ILLINOIS WHILE THE
OTHER LOW HAS STALLED OUT ACROSS THE DAKOTAS. A COUPLE BANDS OF
SNOW DEVELOPED ACROSS THE REGION THIS AFTERNOON WHERE THE LIFT
FROM THE TROUGH WAS STRONG ENOUGH TO SATURATE THROUGH THE COLUMN.
AS THE LIFT WEAKENS TONIGHT AND DRY MID LEVEL AIR ADVECTS IN FROM
THE NORTH...EXPECT THAT THE SNOW WILL QUICKLY COME TO AN END FROM
NORTH TO SOUTH. THE 24.16Z HRRR KEEPS THIS SNOW ACROSS PORTIONS OF
NORTHEAST IOWA AND SOUTHEAST MINNESOTA THROUGH 5Z...WHICH APPEARS
TO BE REASONABLE GIVEN RECENT TRENDS. OVERALL IMPACT OF THIS SNOW
HAS BEEN ON THE LOW SIDE WITH ROAD TEMPERATURES IN THE 40 TO 50F
RANGE THIS AFTERNOON WITH MUCH OF THE SNOW MELTING ON CONTACT
WITH THE ROADS. HOWEVER...AS THE SUN AND TEMPERATURES DROP
TONIGHT...SOME OF THE WET ROADS COULD HAVE SOME ICY PATCHES FORM
IF THEY DO NOT DRY OFF FIRST. CLOUD COVER WILL REMAIN OVERCAST
THROUGH THE NIGHT AS LOW AND HIGH LEVEL MOISTURE CONTENT REMAINS
FAIRLY HIGH.
WITH THE DRY NORTHWEST FLOW IN PLACE THROUGH MID WEEK FROM THE
SURFACE THROUGH THE UPPER PORTIONS OF THE ATMOSPHERE...THE MAIN
FORECAST CHALLENGES WILL BE WITH CLOUD COVER AND TEMPERATURES. HOW
THE TEMPERATURES PAN OUT WILL DIRECTLY TIE INTO HOW MUCH CLOUD
COVER THERE IS. BASED ON 24.12Z NAM/GFS RH FIELDS AND
SOUNDINGS...IT APPEARS THAT THE CLOUDS SHOULD LINGER THROUGH
TUESDAY BEFORE A RIDGE OF HIGH PRESSURE MOVES IN FROM THE WEST
TUESDAY NIGHT. THERE COULD BE A FEW BREAKS IN THE CLOUDS ON
TUESDAY...BUT OVERALL BELIEVE THAT THE SKIES WILL MAINLY BE CLOUDY
UNTIL THE RIDGE GETS IN. 850MB TEMPERATURES DO DROP SLIGHTLY OVER
THE NEXT COUPLE DAYS...FROM -10C TO -12C...BUT THEN START TO
REBOUND GOING INTO WEDNESDAY AS THE RIDGE AXIS APPROACHES FROM THE
WEST. BASED ON THE GRADUALLY THINNING CLOUD COVER...HAVE GONE
WITH A SIMILAR GRADUAL INCREASE IN TEMPERATURES.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
221 PM CDT SUN MAR 24 2013
THIS WARMING TREND WILL CONTINUE THROUGH THE REST OF THE WEEK AS
THE LONG WAVE UPPER LEVEL TROUGH OVER THE EASTERN HALF OF THE US
PROGRESSES EASTWARD AND UPPER LEVEL RIDGING TRIES TO DEVELOP
ACROSS THE CENTRAL US. WARMER LOW LEVEL AIR WILL ADVECT INTO THE
REGION FROM THE SOUTHWEST WITH 850MB TEMPERATURES REACHING +2C BY
SATURDAY AHEAD OF THE NEXT SYSTEM TO IMPACT THE REGION. THIS NEXT
SYSTEM THAT THE 24.12Z GFS/ECMWF BRING INTO THE REGION ON
SATURDAY/SATURDAY NIGHT IS CURRENTLY OFF THE WEST COAST OF ALASKA
AND APPEARS TO STALL OUT OVER THE PACIFIC NW AROUND MID WEEK.
THERMAL PROFILES FROM BOTH THE 24.12Z GFS/ECMWF SUGGEST THAT THE
PRECIPITATION WILL REACH THE GROUND AS RAIN DUE TO A DEEP WARM
LAYER FROM THE SURFACE UP TO 800MB. WITH FORECAST HIGH
TEMPERATURES OF AROUND 50F FRIDAY INTO SUNDAY AND A PERIOD OF RAIN
COMING THROUGH...WILL HAVE TO WATCH FOR SOME POTENTIAL FLOODING ON
AREA RIVERS SHOULD THIS FORECAST CONTINUE TO TREND THIS WAY.
&&
.AVIATION...THROUGH 18Z MONDAY
1247 PM CDT SUN MAR 24 2013
BANDS OF LIGHT SNOW ARE CURRENTLY ROTATING THROUGH THE REGION AND
WILL PRODUCE MVFR TO IFR CONDITIONS AT KRST/KLSE INTO THE
AFTERNOON. VISIBILITIES HAVE BOUNCED AROUND BETWEEN 5 AND
2SM...AND AS SATURATION WINS OUT AGAINST THE DRIER AIR IN THE LOW
LEVELS...WILL GO AHEAD AND FAVOR THE LOWER END OF PROBABILITIES
THIS AFTERNOON. THE LOWER CEILINGS ARE LAGGING SLIGHTLY...BUT IFR
CEILINGS SHOULD REACH KRST IN A FEW HOURS. CURRENT THINKING IS
THAT KLSE SHOULD REMAIN WITH LOW-END MVFR CEILINGS. LATEST MESO
MODELS SHOW THE BANDS OF LIGHT SNOW LASTING INTO THE EARLY EVENING
HOURS...BEFORE PRECIPITATION WANES AND MOVES SOUTH/EAST. CLOUDS
WILL PERSIST THROUGH THE REMAINDER OF THE PERIOD...AND SHOULD
GENERALLY BE IN THE 1500 TO 2500 FT RANGE ONCE THE SNOW ENDS. THERE
COULD BE SOME LIFTING/IMPROVEMENT IN THE MORNING HOURS
MONDAY...BUT CONFIDENCE IN THIS MESSY CYCLONIC FLOW IS LOW...SO
HAVE REMAINED ON THE PESSIMISTIC SIDE OF MODEL GUIDANCE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
221 PM CDT SUN MAR 24 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION.....ZT
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1146 AM CDT SUN MAR 24 2013
.UPDATE...
WATER VAPOR IMAGERY AND 500MB RUC ANALYSIS ARE SHOWING A SHORTWAVE
MOVING NORTHEAST ACROSS WISCONSIN THIS MORNING. THIS AREA IS ALSO
BENEATH UPPER LEVEL DIVERGENCE DUE TO THE LOCATION OF THE UPPER JET.
PERIODS OF LIGHT SNOW DEVELOPED ACROSS MUCH OF SOUTHERN WI DURING
THE MORNING.
A BAND OF HIGHER REFLECTIVITY SET UP OVER THE CENTRAL PART OF THE
FORECAST AREA FROM MADISON THROUGH WATERTOWN AND NOW JUNEAU INTO
OZAUKEE COUNTY. THIS AREA SEEMS TO BE COINCIDENT WITH WEAK 700-600MB
WARM AIR ADVECTION AND FRONTOGENESIS. OTHER OBSERVATION SITES AND
RADAR SHOW LIGHT SNOW ACROSS OTHER PARTS OF THE FORECAST AREA LATE
THIS MORNING. VISIBILITIES WITHIN THE AREAS OF HIGHER REFLECTIVITY
ARE DOWN TO A HALF MILE. THE BANDS ARE MOVING SLOWLY...SO LOCATIONS
UNDER A BAND COULD SEE AN INCH ACCUMULATION WITHIN AN HOUR. THERE IS
NO SNOW FALLING IN SOUTHERN MILWAUKEE COUNTY AND RACINE AND KENOSHA
COUNTIES AT THIS TIME...AND NOT SURE IF/WHEN IT WILL FILL IN.
THE SHORTWAVE WILL CONTINUE OFF TO THE NORTHEAST AND THE MAIN UPPER
LOW OVER MISSOURI WILL MOVE EAST TODAY. THE PRECIPITATION ON THE
NORTH SIDE OF THAT UPPER LOW AND WITHIN THE INVERTED SURFACE TROUGH
SHOULD CLIP SOUTHWEST AND SOUTH CENTRAL WI DURING THE AFTERNOON.
MUCH LESS CONFIDENCE ON THE PRECIP MAKING IT INTO SOUTHEAST WI.
OVERALL...EXPECTING THE SNOW TO GRADUALLY DIMINISH OVER THE FORECAST
AREA THIS AFTERNOON GIVEN THE LOSS OF THE BETTER UPPER DYNAMICS.
FORECAST MODELS SUGGEST AN AREA OF 700-600MB WARM AIR ADVECTION AND
FRONTOGENESIS SITTING OVER THE CENTRAL FORECAST AREA THROUGH THE
AFTERNOON SO THERE MAY BE A BAND OF HEAVIER SNOW THAT PERSISTS.
THEN THERE IS THE LAKE EFFECT COMPONENT OF THE SNOW. RECENT AMDAR
AIRCRAFT SOUNDINGS FROM MITCHELL MILWAUKEE AIRPORT SHOW 850MB TEMP
OF -7 TO -8C WHICH WOULD GIVE A LAKE-850MB TEMP DIFFERENCE OF 9 TO
10C...WHICH IS MARGINAL FOR LAKE EFFECT SNOW PRODUCTION. EXPECT THE
LAKE TO CONTRIBUTE VERY LIGHT SNOW TO EASTERN PORTIONS OF THE
FORECAST AREA. SOUTHEAST WI WILL HAVE A BETTER CHANCE OF SEEING THIS
SNOW LATER THIS EVENING AS THE WINDS SHIFT TO THE NORTH.
&&
.AVIATION/18Z TAFS/...
SLOW-MOVING AREAS OF HEAVIER SNOW APPARENT ON RADAR IMAGERY COULD
PRODUCE A QUICK INCH OF SNOW IN AN HOUR. VISIBILITIES DOWN TO A HALF
MILE HAVE BEEN REPORTED WITHIN THESE BANDS. PERIODS OF LIGHT SNOW IS
EXPECTED TO PERSIST ACROSS ALL OF SOUTHERN WI THROUGH THE AFTERNOON
AND DIMINISH BY EARLY EVENING. MVFR CEILINGS WILL PREVAIL...ALTHOUGH
CIGS COULD DIP TO IFR IN THE HEAVIER SNOW BANDS.
THE SURFACE TO 5000 FT FLOW INCREASES TONIGHT AND SWITCHES FROM EAST
TO NORTHEAST. INSTABILITY OVER THE LAKE WILL HELP PRODUCE LAKE
EFFECT SNOW SHOWERS NEAR LAKE MICHIGAN AS THE SYSTEM SNOW SLOWLY
DIMINISHES. ACCUMULATIONS TONIGHT SHOULD BE SPOTTY AND LESS THAN 1
INCH.
&&
.MARINE...
SHORT TERM MODELS ARE SHOWING HIGHER WINDS DEVELOPING OVER SOUTHERN
LAKE MICHIGAN LATE THIS AFTERNOON THROUGH MUCH OF TONIGHT. UPGRADED
TO A GALE WARNING FOR THE SOUTHERN MARINE ZONE FROM WIND POINT TO
WINTHROP HARBOR FROM 22Z THROUGH 09Z TONIGHT. WILL NEED TO RAMP DOWN
TO A SMALL CRAFT ADVISORY AGAIN AFTER THAT EXPIRES.
A SMALL CRAFT ADVISORY IS IN EFFECT ELSEWHERE THROUGH MONDAY NIGHT
DUE TO BRISK NORTHEAST WINDS AND HIGH WAVES. THE BRISK WINDS WILL BE
PRODUCED BY STRONG LOW PRESSURE SLOWLY MOVING ALONG THE OHIO RIVER
VALLEY.
&&
.PREV DISCUSSION... /ISSUED 331 AM CDT SUN MAR 24 2013/
SHORT TERM...
TODAY AND TONIGHT-FORECAST CONFIDENCE MEDIUM.
AN INITIAL 500MB SHORTWAVE WILL MOVE NORTHEAST THROUGH SOUTHERN
WISCONSIN TODAY. MODELS SHOW AN ASSOCIATED BULLS-EYE OF UPPER LEVEL
DIFLUENCE AT JET STREAM LEVEL. SATELLITE PICTURES REFLECT THESE
FEATURES WITH COOLER AND HIGHER CLOUD TOPS. WEAK ISENTROPIC LIFT IS
ALSO FORECAST WITH THIS SHORT WAVE IN THE 10 TO 20 THSD FT LAYER
WHERE IT SATURATES IN THE -12 TO -18C RANGE. CORRESPONDINGLY...RADAR
SHOWS LIGHT SNOW TRYING TO INCH IT/S WAY NORTHEAST INTO SOUTHERN
WI...BUT NOT MUCH REACHING THE GROUND DUE TO DRY NORTHEAST LOW-LEVEL
FLOW. BLEND OF MODELS SUGGESTS SOUTHWEST HALF OF MY COUNTY WARNING
AREA HAS BEST CHANCES FOR SOME LIGHT SNOW TODAY...WITH ACCUMS LESS
THAN 1 INCH. NORTHEAST PART OF MY COUNTY WARNING AREA WILL BE LAST
TO SEE ANY SNOW. MAX TEMPS TODAY IN THE LOWER TO MID 30S...SO ACCUMS
ON ROAD SURFACES SHOULD BE MINIMAL.
FOR TONIGHT LOW-LEVEL FLOW SWITCHES FROM EAST TO NORTHEAST AS THE
UPPER LOW AND SURFACE LOW SWING EAST-NORTHEAST UP THE OHIO RIVER
VALLEY. NOT MUCH IN THE WAY OF SHORT-WAVE ENERGY FOR SOUTHERN
WISCONSIN TONIGHT. ALSO...MODELS CONTINUE TO SHOW MID-LEVEL DRYING
AND NO ISENTROPIC LIFT...SO CHANCES OF GENERAL LIGHT SNOW DROP OFF
TONIGHT. HOWEVER...MODELS DO SHOW A MORE FAVORABLE NORTHEAST FETCH
OVER LAKE MICHIGAN INTO SOUTHEASTERN WISCONSIN. DELTA-T VALUES ARE
ON ORDER OF 10 TO 12 SUGGESTING SOME LAKE-EFFECT SHOWERS WILL
DEVELOP. BUFKIT SOUNDINGS DO DEEPEN THE NEAR SATURATED LOW-LEVEL AIR
NEAR LAKE MICHIGAN TONIGHT...UP TO 6 TO 7 THSD FT AT MILWAUKEE BY
END OF NIGHT. WILL KEEP MENTION OF CHANCE OF SNOW SHOWERS NEAR LAKE
MICHIGAN TONIGHT.
MONDAY-FORECAST CONFIDENCE HIGH
LOW OVER OHIO FILLS RAPIDLY AS COASTAL SECONDARY CYCLOGENESIS
TAKES OVER IN THE MIDDLE ATLANTIC REGION. FLOW REGION THROUGH DEEP
LAYER TRANSITIONS FROM NORTHEAST TO NORTHERLY...AND 500 MB HEIGHTS
RISE ABOUT 50 METERS OVER SOUTHERN WISCONSIN. 850 MB TEMPS AROUND
-10C RESULT IN LAKE DELTA T OF ABOUT 13C. RAN THROUGH LAKE SNOW
CHECKLIST AND IT INDICATES A MINOR EVENT...PERHAPS AN INCH. HAVE
SCATTERED SNOW SHOWERS NEAR THE SHORE BUT THIS MAY NEED TO BE
BUMPED UP LATER.
TUESDAY-FORECAST CONFIDENCE HIGH
FLOW REGIME TURNS FROM NORTHERLY TO NORTHWEST...WITH LITTLE CHANGE
IN AIRMASS. STILL RUNNING ABOUT 10 DEGREES BELOW NORMAL FOR LATE
MARCH WITH CONSENSUS 925 MB TEMPS ONLY RISING ABOUT 1C FROM
MONDAY TO ABOUT -4 OR -5C. NOT IMPOSSIBLE FOR CONVECTIVE SNOW
SHOWERS BENEATH UPPER TROUGH BUT THE MODELS BATTING
AVERAGE...ESPECIALLY THE GFS...NOT TOO GOOD AND SEEMS TO OVERDO
THESE SITUATIONS.
LONG TERM...
WEDNESDAY AND THURSDAY-FORECAST CONFIDENCE MEDIUM
RATHER QUIET PATTER WITH NORTHWEST FLOW ALOFT AND POLAR HIGH
COVERING THE GREAT LAKES AREA. HEIGHTS GRADUALLY RISE ABOUT 30 OR
40 METERS EACH DAY AND GRADUAL MODERATION OF AIR MASS CONTINUES.
CONSENSUS 925 TEMPS RISE TO ABOUT -3C ON WEDNESDAY AND GET TO
ABOUT 0C ON THURSDAY. NOT QUITE READY TO DANCE IN THE STREETS BUT
UPPER 30S TO LOWER 40S SOUNDS PRETTY GOOD EVEN IF STILL 5 TO 10
DEGREES BELOW NORMAL.
FRIDAY AND SATURDAY-FORECAST CONFIDENCE MEDIUM
MODELS DO NOT PROVIDE MUCH CONFIDENCE IN TIMING OF ANY MINOR
EVENTS IN NORTHWEST FLOW. GEM HAS DECENT SHORTWAVE ON FRIDAY BUT
GFS AND ECMWF SHOW PERSISTENT SURFACE HIGH.
GFS AND ECMWF STARTING TO COME INTO BETTER AGREEMENT WITH SYSTEM
SATURDAY OVER MN/IA AREA AND MAY NEED TO ADD POPS SATURDAY NIGHT
IN LATER FORECASTS. FOR NOW LOOKS LIKE CONTINUED MODERATING TREND
WITH 925 MB TEMPS IN THE 0 TO +2C RANGE...WITH HIGHS RISING INTO
THE MIDDLE 40S. SO WE HAVE A SHOT AT NEAR NORMAL HIGHS BY THE END
OF MARCH.
OF NOTE IS THAT MADISON HAS JUST ONE DAY THIS MONTH WITH HIGH
TEMPERATURES REACHING NORMAL. IN JULY OF 2009 MADISON TIED THE
AVERAGE HIGH 3 TIMES BUT NEVER HAD AN ABOVE AVERAGE HIGH. IT IS
VERY UNUSUAL TO SEE A MONTH GO BY WHERE YOU DO NOT HAVE ABOVE
AVERAGE HIGH TEMPERATURES AT LEAST ONCE. IT WILL BE A CLOSE CALL
WITH UPPER 40S ON SUNDAY THE 31ST.
AVIATION/12Z TAFS/...
STRATUS DECK OFF OF LAKE MICHIGAN WILL KEEP CEILINGS IN THE MVFR
RANGE TODAY AND TONIGHT ACROSS SOUTHERN WISCONSIN. SYSTEM SNOW
SHOULD DROP VISIBILITIES TO 3 TO 5 MILES IN SPOTS. NOT EXPECTING IFR
CONDS DUE TO DRY LOW-LEVEL AIR 5 TO 10 THSD FEET AGL.
LIGHT WET SNOW IS EXPECTED TO SPREAD INTO SOUTHERN WISCONSIN SUNDAY
MORNING AND THEN TAPER OFF SUNDAY EVENING. THE BEST CHANCE FOR SNOW
WILL BE ALONG I-94 AND SOUTH SO THIS INCLUDES ALL THE TAF SITES.
HIGHEST ACCUMULATIONS OF 1 INCH OR LESS WILL LIKELY BE SOUTH AND
WEST OF THE TAF SITES...ESPECIALLY TOWARD THE WI/IA/IL BORDER.
THE SURFACE TO 5000 FT FLOW INCREASES TONIGHT AND SWITCHES FROM EAST
TO NORTHEAST. INSTABILITY OVER THE LAKE WILL HELP PRODUCE LAKE
EFFECT SNOW SHOWERS NEAR LAKE MICHIGAN AS THE SYSTEM SNOW SLOWLY
DIMINISHES. ACCUMULATIONS TONIGHT SHOULD BE SPOTTY AND LESS THAN 1
INCH.
MARINE...
A SMALL CRAFT ADVISORY IS IN EFFECT THIS MORNING THROUGH MONDAY
NIGHT DUE TO BRISK NORTHEAST WINDS AND HIGH WAVES. THE BRISK WINDS
WILL BE PRODUCED BY STRONG LOW PRESSURE SLOWLY MOVING ALONG THE
OHIO RIVER VALLEY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM CDT THIS AFTERNOON FOR LMZ646.
GALE WARNING FROM 5 PM THIS AFTERNOON TO 4 AM CDT MONDAY FOR
LMZ646.
SMALL CRAFT ADVISORY UNTIL 10 PM CDT MONDAY FOR LMZ643>645.
&&
$$
UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...KAPELA
MONDAY THROUGH SATURDAY...CRAVEN
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1142 PM CDT SAT MAR 23 2013
.SHORT TERM...TONIGHT THROUGH TUESDAY
321 PM CDT SAT MAR 23 2013
THE MAIN FOCUS THROUGH EARLY NEXT WEEK IS WITH THE SNOW THAT WILL
MOVE IN OVERNIGHT AND END SUNDAY NIGHT.
BROAD MID LEVEL TROUGHING IN PLACE ACROSS THE EASTERN ROCKIES AND
WESTERN PLAINS WITH A NUMBER OF TROUGHS EMBEDDED WITHIN THIS FLOW.
THE FIRST MID LEVEL SHORT WAVE TROUGH HAS PROPAGATED ACROSS IOWA
AND SOUTHERN MINNESOTA AND HAS BROUGHT AN INCREASE IN HIGH LEVEL
CLOUD COVER WITH IT. THERE IS TOO MUCH DRY LOW LEVEL AIR IN PLACE
RIGHT NOW FOR THIS FEATURE TO PRODUCE ANY PRECIPITATION...SO THE
FOCUS THEN GOES TO THE NEXT...MORE VIGOROUS CLOSED MID LEVEL LOW
THAT CURRENTLY IS IN EASTERN COLORADO AND SITS AT THE BASE OF THE
LONG WAVE TROUGH. THIS FEATURE WILL TAKE A DUE EAST TRACK ACROSS
THE MID MISSISSIPPI VALLEY REGION TONIGHT INTO TOMORROW. THIS
TROUGH WILL PROVIDE THE MAIN LIFTING MECHANISM FOR THE NEXT PERIOD
OF SNOW THAT WILL MOVE IN OVERNIGHT AND LAST THROUGH MUCH OF THE
DAY. AT THE SURFACE...BROAD RIDGING EXTENDS ACROSS CENTRAL CANADA
WITH A LOW ANALYZED OVER NEW MEXICO. IN BETWEEN THESE TWO
FEATURES...IT IS MAINLY JUST A WEST TO EAST PRESSURE GRADIENT WITH
AN INVERTED TROUGH EXTENDING NORTH OUT OF THE LOW ACROSS EASTERN
COLORADO. THE 23.12Z SUITE OF MODEL GUIDANCE ALL APPEAR TO HAVE
INITIALIZED WELL...THOUGH THE 23.12Z TO 23.18Z RAP IS WAY OFF ON
THE SNOW DEPTH WHICH CREATES WAY TOO WARM OF TEMPERATURES IN THE
AREAS WHERE THERE IT THINKS THERE IS NO SNOW PACK.
AS THE CLOSED MID LEVEL LOW TRACKS TO THE EAST TONIGHT...THE
INVERTED SURFACE TROUGH WILL BECOME A LITTLE MORE AMPLIFIED AND
BECOME THE MAIN LOW LEVEL CONVERGENCE FEATURE THAT THE SNOW WILL
BECOME FOCUSED AROUND. THE DEEPER LIFT WILL COME IN AHEAD OF THE
TROUGH WITH MUCH OF THE HIGHEST OMEGA SHOWING UP IN THE 600-500MB
RANGE. WITH THE OVERALL LIFT NOT BEING VERY DEEP...THE CONCERN IS
WITH A DRY LAYER BETWEEN 800-600MB THAT THIS LIFT WILL HAVE TO
OVERCOME...PARTICULARLY THE FARTHER NORTH AND EAST YOU GET FROM
THE CORE OF THE SYSTEM. THE 23.12Z NAM/GFS BUFKIT SOUNDINGS DO
SHOW A DECENT SIZED DENDRITIC GROWTH ZONE THAT IS ABOUT 150MB DEEP
FOR MUCH OF THE EVENT...BUT THE LIFT IS ONLY IN THAT SECTION OF
THE SOUNDING FOR A BRIEF PERIOD. ANY DENDRITES THAT FALL THROUGH
THE DRY LAYER WILL LIKELY SHRINK AS THEY MAKE IT THROUGH ON THEIR
WAY DOWN THE GROUND. OVERALL...FAIRLY CONFIDENT THAT AREAS ALONG
AND WEST OF THE MISSISSIPPI RIVER WILL SEE A LIGHT ACCUMULATING
SNOW FROM LATE TONIGHT THROUGH MUCH OF THE DAY. GENERALLY HAVE
ABOUT 1 TO 2 INCHES RUNNING ACROSS NORTHEAST IOWA AND A PORTION OF
SOUTHEAST MINNESOTA WITH LESSER AMOUNTS ALONG AND NORTHEAST OF THE
MISSISSIPPI RIVER. AS THE NORTHERLY LOW TO MID LEVEL FLOW KICKS IN
SUNDAY NIGHT...THE 800-600MB WEDGE OF DRY AIR GETS PULLED BACK
DOWN TO THE SOUTH AND SHOULD BRING AN END TO THE SNOW FAIRLY
QUICKLY IN THE EVENING.
BEYOND THIS...WE STAY IN LOW LEVEL CYCLONIC FLOW WITH WEAK RIDGING
ALOFT IN THE WAKE OF THE TROUGH. MAY STILL SEE SOME FLURRIES ON
MONDAY DUE TO SOME WEAK LOW LEVEL LIFT DUE TO THE CYCLONIC FLOW
WITH THE SATURATED PORTION OF THE LOW LEVEL PROFILE BEING COLD
ENOUGH WHERE ICE WILL BE PRESENT. OTHERWISE THE CHALLENGES WILL BE
WITH TEMPERATURES AND CLOUD COVER WITH SOME CLEARING POSSIBLE
GOING INTO TUESDAY.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
321 PM CDT SAT MAR 23 2013
THE GOOD NEWS IN THE LONG TERM PERIOD IS THAT IT APPEARS THE MID LEVEL
TROUGH STARTS TO BREAK DOWN AND PUSH TO THE EAST WITH GRADUAL MID
LEVEL RIDGING DEVELOPING ACROSS THE WESTERN HALF OF THE US. WHILE
THE UPPER MISSISSIPPI RIVER VALLEY IS STILL IN GENERAL NORTHWEST
FLOW ALOFT...THE LOW LEVEL FLOW BECOMES MORE SOUTHWESTERLY WITH
850MB TEMPERATURES SLOWLY INCREASING FROM -10C TUESDAY NIGHT TO
AROUND 0C BY FRIDAY. PRECIPITATION WISE...THERE IS SOME SUGGESTION
THAT THE VORT MAX CURRENTLY OVER THE WESTERN PART OF HUDSON BAY
EVENTUALLY GETS CAUGHT IN THE NORTHWEST FLOW ALOFT AND PULLS IT
DOWN INTO THE UPPER GREAT LAKES BY FRIDAY NIGHT. WITH MUCH OF THE
FORCING FROM THIS SYSTEM LIKELY STAYING TO THE NORTHEAST...HAVE
KEPT THE FORECAST DRY FROM MID WEEK INTO SATURDAY.
&&
.AVIATION...THROUGH 06Z MONDAY
1141 PM CDT SAT MAR 23 2013
A TROUGH OF LOW PRESSURE EXTENDING NORTH-SOUTH THROUGH KLSE IS
FORECAST TO INTENSIFY THIS MORNING...NEAR 12Z...AS A WAVE IN THE
UPPER LEVELS OF THE TROPOSPHERE APPROACHES IT. THIS WILL
EVENTUALLY PRODUCE SNOW...ONCE DRIER AIR IN THE LOWER LEVELS IS
OVERWHELMED. CURRENT THINKING REMAINS THE SAME THAT KRST HAS THE
BETTER CHANCE OF SEEING THIS SNOW...ALONG THE TRACK OF THAT
WAVE...WITH VISIBILITIES DROPPING TO MVFR BY 12Z AND IFR SHORTLY
THEREAFTER. CEILINGS SHOULD FALL AT LEAST TO MVFR. SINCE THE
FORCING LOOKS WEAK AND THE LOW LEVEL FLOW IS A DRIER NORTHEAST
DIRECTION...DID NOT INTRODUCE ANY IFR CEILINGS. KLSE IS EITHER ON
OR TO THE EAST SIDE OF THE TROUGH...SO THE EAST TO NORTHEAST FLOW
OF DRY AIR AT BOTH THE LOWER AND MID LEVELS OF THE TROPOSPHERE
WILL HAVE MORE OF AN INFLUENCE. AS SUCH...KEPT CEILINGS VFR FOR
NOW AND MAINTAINED ONLY AN MVFR PERIOD OF VISIBILITY BETWEEN
15-21Z. IT APPEARS THAT THE SNOW SHOULD END AT BOTH TAF SITES BY
00Z AS THE TROUGH SWINGS SOUTHWEST. UNSURE EXACTLY HOW CEILINGS
WILL PLAY OUT ONCE THE SNOW ENDS. FOR NOW HELD THEM MAINLY
STEADY...VFR AT KLSE AND MVFR AT KRST. HOWEVER...IT IS POSSIBLE
SOME CLEARING MAY TRY TO WORK IN DEPENDING ON HOW MUCH DAYTIME
MIXING AND DRYING OCCURS DURING THE AFTERNOON OVER NORTHERN
WISCONSIN. PARTIAL CLEARING WOULD BE MORE LIKELY AT KLSE BEING
CLOSER TO THE SOURCE REGION OF DRIER AIR.
TOTAL SNOWFALL AMOUNTS AGAIN LOOK LIGHT...MAINLY AN INCH OR
LESS...AND PERHAPS ONLY A TRACE AT KLSE. WITH MOST OF THE SNOW
FALLING DURING THE DAY...A LOT OF IT IS LIKELY TO MELT TOO WITH
THE HIGH SUN ANGLE NOW.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
321 PM CDT SAT MAR 23 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1243 AM CDT TUE MAR 26 2013
.DISCUSSION...
819 PM CDT
LAKE EFFECT SNOW SHOWERS CONTINUE TO STREAM ONSHORE ACROSS
SOUTHEAST COOK...LAKE...AND PORTER COUNTIES. LATEST RADAR TRENDS
AND OBS SHOW SOME BETTER ORGANIZATION WHICH IS SUPPORTED BY NEAR
TERM RAP SOUNDINGS THAT SHOW INVERSION HEIGHTS RISING CLOSER TO
7000 FT. 00Z GREEN BAY RAOB SHOWS AN INVERSION AROUND 6800 FT
WITH AN H85 TEMP AT -11C WITH LAKE WATER TEMP ROUGHLY AROUND +3C
YIELDING A 14C DIFFERENCE. LOW LEVEL WINDS HAVE BEGUN TO TURN MORE
NORTHWESTERLY...AT LEAST SLIGHTLY...OVER THE LAST FEW HOURS WHICH
SUPPORTS A GRADUAL EASTWARD SHIFT IN THE MORE FOCUSED ACTIVITY AND
BETTER RETURNS HAVE BEEN OCCURRING OVER PORTER COUNTY. OVERALL THE
GOING FORECAST REFLECTS THE ABOVE SO WILL ONLY MAKE MINOR TWEAKS
FOR NOW. STILL EXPECT THAT A FEW INCHES OF ACCUMULATION IS
POSSIBLE THROUGH THE OVERNIGHT ACROSS PORTER COUNTY BUT COVERAGE
OF ACCUMS MAY BE SOMEWHAT ISOLATED WITH MORE WIDESPREAD LIGHTER
AMOUNTS POSSIBLE GIVEN THE TRANSIENT NATURE OF THE BANDS.
ELSEWHERE...FLURRIES CONTINUE WITH NORTH-NORTHWEST WINDS EASING.
HAVE ADJUSTED TEMP TRENDS TO SUPPORT A SLOWER FALL INTO THE
OVERNIGHT.
MDB
//PREV DISCUSSION...
318 PM CDT
MAIN CONCERNS THIS FORECAST CYCLE ARE INITIALLY LAKE EFFECT SNOW
SHOWER TRENDS INTO TUESDAY...AND THEN TIMING OF NEXT COLD FRONT OVER
THE WEEKEND AND ASSOCIATED CHALLENGES OF TEMPS.
BROAD UPPER TROUGH DOMINATES THE EASTERN CONUS THIS AFTERNOON WITH
CLOSED LOW WHICH BROUGHT HEAVY SNOW TO THE MIDWEST ON SUNDAY/SUNDAY
NIGHT NOW PROPAGATING ACROSS THE MID-ATLANTIC REGION. SURFACE LOW
PRESSURE CONTINUES TO FILL OVER THE APPALACHIANS AS COASTAL LOW
DEEPENS OFF THE JERSEY SHORE...WITH BROAD AREA OF COOL CYCLONIC LOW
LEVEL FLOW TRAILING ACROSS THE GREAT LAKES AND MISSISSIPPI VALLEY
REGION. THIS HAS PRODUCED PERSISTENT FLURRIES/LIGHT SNOW SHOWERS
WITH STEEP LOW LEVEL LAPSE RATES...AS WELL AS LAKE EFFECT SNOW
SHOWERS WHICH HAVE GRADUALLY BECOME BETTER ORGANIZED THIS AFTERNOON.
LIGHT SNOW SHOWERS HAVE GENERALLY BEEN DECREASING ACROSS AREAS AWAY
FROM THE LAKE THIS AFTERNOON WITH WEAK SYNOPTIC SUBSIDENCE/HEIGHT
RISES IN THE WAKE OF THE SHEARED MID-LEVEL VORT DRIFTING SOUTH AWAY
FROM OUR AREA...THOUGH FORECAST SOUNDINGS SUPPORT CONTINUED STRATOCU
LINGERING TONIGHT WHICH WILL PROBABLY STILL PRODUCE SOME SCATTERED
INCONSEQUENTIAL FLURRIES AT TIMES. GUIDANCE DOES INDICATE A WEAK MID
LEVEL SHORT WAVE WILL APPROACH FROM THE NORTH/NORTHWEST LATE TONIGHT
AND WILL CROSS THE AREA TUESDAY MORNING...WHICH ALTHOUGH NO
SIGNIFICANT QPF IS INDICATED WILL LIKELY CONTINUE TO SUPPORT SOME
FLURRIES INTO TUESDAY MORNING. AS FOR THE LAKE EFFECT...BOUNDARY
LAYER WINDS ARE STARTING TO BACK FROM NORTHEAST TO MORE NORTHERLY...
AND WERE HELPING FOCUS CONVERGENCE FOR A NORTH-SOUTH LAKE-PARALLEL
BAND TO BECOME EVIDENT IN REGIONAL RADAR IMAGERY. WINDS CONTINUE TO
BACK GRADUALLY TO MORE NORTHWEST THROUGH TUESDAY MORNING WHICH
SHOULD ALLOW THIS BAND TO SHIFT ACROSS NORTHWEST INDIANA AND
EVENTUALLY EAST OF PORTER COUNTY AND OUT OF OUR CWA TUESDAY
AFTERNOON. THERMODYNAMIC PROFILES REMAIN FAIRLY MARGINAL FOR STRONG
LAKE EFFECT...WITH DELTA T VALUES GRADUALLY APPROACHING +14 OR SO
AND WITH EQUILIBRIUM LEVELS 6000-7000 FT. THUS WHILE ACCUMULATIONS
ARE NOT EXPECTED TO BE GREAT...WEAK LES EVENT IS EXPECTED TO PERSIST
AND HAVE BUMPED UP POPS ESPECIALLY OVER NORTHWEST INDIANA
TONIGHT/EARLY TUES. WITH LIGHT SNOW AND TEMPS ABOVE FREEZING NOT
MUCH ACCUMULATING ATTM...THOUGH ACCUMULATIONS OF AN INCH OR TWO ARE
LIKELY OVERNIGHT WITH SLIGHTLY COOLER TEMPS AND MORE ORGANIZED BAND.
BEYOND TUESDAY...UPPER FLOW REMAINS NORTHWEST WHILE HEIGHTS
GRADUALLY INCREASE AS EASTERN TROUGH SLOWLY MOVES AWAY. WEAK SURFACE
HIGH PRESSURE RIDGE MOVES INTO THE AREA BY LATE WEDNESDAY AND
THURSDAY WHICH WILL PROVIDE DRY WEATHER WITH SLOWLY MODERATING
TEMPS...LIKELY REACHING THE MID 40S BY THURSDAY.
GUIDANCE IS IN GOOD AGREEMENT IN DEPICTING AN UPPER TROUGH DROPPING
OUT OF CANADA AND AMPLIFYING ACROSS THE UPPER MIDWEST THIS WEEKEND.
SURFACE LOW PRESSURE INITIALLY DEVELOPS TO OUR NORTH/NORTHWEST ON
SATURDAY...WHICH ALLOWS OUR LOW LEVEL FLOW TO BECOME SOUTHERLY AS
THE SURFACE RIDGE DRIFTS AWAY TO THE EAST. WARMING COMMENCES... WITH
GUIDANCE INDICATING UPPER 40S/LOW 50S BY THE WEEKEND. MODELS REMAIN
A BIT CONFLICTED IN THE LONGER TERM WITH HOW QUICKLY THE COLD FRONT
ASSOCIATED WITH THE UPPER MIDWEST/LAKE LOW MOVES THROUGH HOWEVER.
THE GFS...WHILE CONSISTENT WITH ITSELF IS QUICKEST AND MOVES THE
FRONT THROUGH SATURDAY NIGHT...WHILE THE ECMWF BRINGS IT THROUGH
DURING THE DAY SUNDAY. THIS HAS SIGNIFICANT IMPLICATIONS ON TEMPS
ESPECIALLY SUNDAY...WITH ANOTHER DAY OF 50 DEGREE WARMTH ON SUNDAY
WITH THE SLOWER ECMWF SOLUTION. HAVE LEANED IN FAVOR OF THE USUALLY
CONSISTENT PERFORMING ECMWF...WITH 50S ACROSS THE SOUTHEAST 2/3 OR
SO OF THE CWA SUNDAY WITH NEAR 50 NORTHWEST CLOSER TO APPROACHING
FRONT. IN EITHER CASE...IT APPEARS THAT OUR THERMAL PROFILES WILL BE
WARM ENOUGH TO RESULT IN FRONTAL/PRE-FRONTAL PRECIP FALLING IN THE
FORM OF RAIN SATURDAY NIGHT INTO SUNDAY...PERHAPS MIXING WITH WET
SNOW BEFORE ENDING BEHIND THE FRONT SUNDAY NIGHT. EARLY NEXT WEEK
SHOWS EVEN BIGGER DIFFERENCES IN EVOLUTION OF PATTERN WITH THE GFS
REBUILDING WARMTH QUICKLY...WHILE THE ECMWF INDICATES MORE OF A COOL
DOWN BACK TO SUB-NORMAL TEMPS BEHIND THE FRONT MONDAY. 12Z EC NOT AS
COLD AS THE 00Z RUN...THOUGH HAVE AGAIN SHADED AWAY FROM THE 50S AS
PRODUCED BY THE GFS. WILL PULL FOR THE WARMER GFS SOLUTION HOWEVER!
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
*NONE.
TRS
//DISCUSSION...UPDATED 06Z...
LIGHT LAKE EFFECT SNOW SHOWERS CONTINUE JUST E OF THE IL SHORE OUT
TO MID-LAKE AND INTO FAR NORTHWEST IN. OFFSHORE OF THE IL. FLOW IN
LOWER LEVELS AND THROUGH THE DEPTH OF THE LAKE EFFECT CLOUDS IS TO
REMAIN BASICALLY OUT OF THE DUE NORTH DURING THE FIRST PART OF THE
OVERNIGHT BEFORE THEY BACK A BIT AND SHIFT TO LAKE EFFECT SNOW
SHOWERS FURTHER EAST ACROSS NORTHWEST IN AND TO FAR SOUTHWEST
LOWER MI AND NORTH CENTRAL IN DURING THE PREDAWN AND TUESDAY
MORNING.
PAIR OF UPPER LOW OVER NEW ENGLAND TO MERGE AS THEY CONTINUE TO
THE EAST ALONG AND OFF THE CANADIAN MARITIMES TODAY WHILE AN UPPER
RIDGE OVER WESTERN NOAM WEAKENS AND BROADENS AS IT MOVES TO THE
NORTHERN AND CENTRAL ROCKIES AND THE 4 CORNERS. A SHORT WAVE
ROTATING WEST SOUTHWEST AC ROS THE SOUTHERN QUEBEC- ONTARIO BORDER
HAS ALREADY STARTED TO TURN TO THE SOUTH IN SATELLITE LOOPS AND
WILL CROSS OVER THEN CENTRAL AND EASTERN GREAT LAKES. MODELS
INDICATE A MID/UPPER SHORT WAVE DROPPING SOUTH OVER THE UPPER
MIDWEST LATE OVERNIGHT AND TUESDAY MORNING WITH A MODERATELY
STRONG VORT MAX CURRENTLY OVER SOUTHERN MN MOVING SOUTHEAST ACROSS
NORTHEAST IA TO CENTRAL IL BY MIDDAY. WHILE LOW LEVELS HAVE
MOISTURE TRAPPED BENEATH AN INVERSION UP AROUND 5K FT IT IS VERY
DRY IN THE MID AND UPPER LEVELS SO ANY UVV RESULTING FROM POSITIVE
VORTICITY ADVECTION ACROSS THE AREA WILL NOT HAVE MOISTURE TO WORK
WITH.
NORTHWEST WINDS WILL BE LESS THAN DURING THE DAY MONDAY AS THE
PRESSURE GRADIENT SLOWLY DECREASES OVER THE AREA AS THE HIGH
PRESSURE RIDGE TO THE WEST GRADUALLY APPROACHES THE AREA.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE ALL FORECAST ELEMENTS.
TRS
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...MVFR IMPROVING TO VFR.
THURSDAY...VFR.
FRIDAY...VFR.
SATURDAY...VFR.
SUNDAY...CHANCE OF RAIN/MVFR.
BMD
&&
.MARINE...
225 PM CDT
STRONG LOW PRESSURE OFF THE MID ATLANTIC COAST WILL MOVE EAST OUT
INTO THE ATLANTIC OCEAN WITH HIGH PRESSURE OVER THE PLAINS BUILDING
EAST INTO THE MISSISSIPPI VALLEY AND WESTERN GREAT LAKES. STRONG
NORTHERLY FETCH WILL KEEP WAVES UP FOR THE NEARSHORE THROUGH TUESDAY
OR TUESDAY NIGHT. FAIRLY LIGHT WINDS ARE EXPECTED WEDNESDAY THROUGH
FRIDAY AS HIGH PRESSURE SETS UP CAMP OVER THE REGION BEFORE SCOOTING
EAST OVER THE WEEKEND ALLOWING FOR SOUTHERLY WINDS TO DEVELOP.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 7 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
513 AM EDT TUE MAR 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 513 AM EDT TUE MAR 26 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A PERSISTENT BLOCKING RIDGE
FROM NRN CANADA INTO HUDSON BAY AND A TROUGH FROM THE CANADIAN
MARITIMES INTO NRN NEW ENGLAND RESULTING IN WEAK NE FLOW THROUGH THE
NRN GRREAT LAKES. AT THE SFC...NRLY FLOW PREVAILED ACROSS LAKE
SUPERIOR BETWEEN A TROUGH INTO THE ERN LAKES AND A RIDGE OVER THE
PLAINS. IR LOOP SHOWED THE BACK EDGE OF THE CLOUDS AND DEEPER
MOISTURE ADVANCING WESTWARD TOWARD THE E SIDE OF LAKE SUPERIOR.
RADAR INDICATED SCT SHSN INTO CNTRL UPPER MI WITH MORE CELLULAR THAN
BANDED PATTERN MORE TYPICAL OF LES. EVEN THOUGH 850 MB TEMPS TO NEAR
-10C ONLY PROVIDED MARGINAL OVER LAKE INSTABILITY...A WEAK SHORTWAVE
TROUGH AND ASSOCIATED 700-300 MB QVECTOR CONV HAS SUPPORTED SHSN
DEVELOPMENT. SNOW/WATER RATIO HAS INCREASED AND -FZDZ POTENTIAL
DIMINISHED WITH MOISTURE THROUGH THE DGZ.
TODAY...AS THE FORCING WITH THE SHRTWV SLIDES OFF TO THE SOUTHEAST
AND THE DEEPER MOISTURE DEPARTS...EXPECT THE SHSN TO QUICKLY
DIMINISH BY LATE MORNING. SO...ADDITIONAL SNOWFALL AMOUNTS OF ONLY A
HALF INCH OR LESS ARE EXPECTED. THERE MAY STILL BE A PERIOD WHERE
SOME -FZDZ IS POSSIBLE AS THE MOIST LAYER FALLS AT OR BELOW THE -10C
LEVEL. WITH DAYTIME HEATING AND GREATER MIXING...THERE MAY EVEN BE A
PERIOD OF SOME CLEARING INTO THE E HALF OF UPPER MI.
OTHERWISE...HIGH TEMPS WILL REMAIN BELOW NORMAL...IN THE LOWER TO
MID 30S.
TONIGHT...ANOTHER BATCH OF 925-850 MB MOISTURE IS EXPECTED TO MOVE
IN FROM THE NORTHEAST BRINGING THE POTENTIAL FOR ANOTHER ROUND OF
LAKE ENHANCED PCPN. SINCE TEMPS NEAR TO THE TOP OF THE MOIST LAYER
AT 850 MB ARE A BIT HIGHER...ONLY TO AROUND -8C...THERE MAY BE A
BETTER CHANCE FOR -FZDZ WITH ANY PCPN THAT DEVELOPS. WITH ONLY A
MODEST NRLY UPSLOPE WIND COMPONENT IN THE 20 TO 25 KNOT RANGE...ONLY
SLIGHT OR LOWER END CHANCE POPS WERE MENTIONED.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 410 AM EDT TUE MAR 26 2013
LINGERING LOW LEVEL MOISTURE ROTATING IN FROM THE NORTH WILL BE
SLOWLY DIMINISHING WITH MUCH OF THE REMAINING FREEZING DRIZZLE AND
LIGHT SNOW SHOWERS/FLURRIES ENDING FOR THE MOST PART ON WEDNESDAY.
MOISTURE WILL BE TRAPPED BELOW 800MB WEDNESDAY MORNING AND FALL
AROUND OR BELOW 900MB BY WEDNESDAY EVENING...UNDER THE STRENGTHENING
INVERSION. WHILE THE MODELS DO SPIT OUT AROUND 0.01IN OR LESS
WEDNESDAY NIGHT AND THURSDAY...SIGNIFICANT PRECIP IS NOT ANTICIPATED.
THE STEADILY WARMING AFTERNOON HIGH TEMPERATURES WILL CONTINUE AS
THE 500MB HIGH OVER HUDSON BAY ON TUESDAY SINKS INTO ONTARIO AND
COMBINES WITH THE RIDGE ALREADY SET UP ACROSS THE WESTERN HALF OF
THE UNITED STATES. 850MB TEMPS AROUND -11C WEDNESDAY MORNING WILL
WARM TO -6C BY 12Z THURSDAY ON CONTINUED NORTHERLY WINDS...AND
REMAIN NEARLY STEADY THROUGH FRIDAY AFTERNOON.
A WEAK SHORTWAVE WILL SWING IN ON THE NORTHWESTERLY FLOW ALOFT
THURSDAY NIGHT INTO EARLY FRIDAY...WITH LITTLE INFLUENCE ON OUR
WEATHER. THE WRAPPED UP 500MB LOW ENCOMPASSING MUCH OF CENTRAL
CANADA FROM MID WEEK ON WILL DIG A TROUGH ACROSS THE NORTHERN PLAINS
FRIDAY NIGHT INTO SATURDAY...AND EXTEND TO THE UPPER GREAT LAKES
FROM SATURDAY THROUGH AT LEAST MONDAY. TIMING AND STRENGTH OF THE
ASSOCIATED COLD FRONT IS STILL IN QUESTION...BUT IT LOOKS LIKE IT
SHOULD BE OVER FAR WESTERN LAKE SUPERIOR SATURDAY AFTERNOON...AND
SLOWLY TRANSITION ACROSS CENTRAL AND EASTERN LAKE SUPERIOR SATURDAY
NIGHT...AS THE SFC LOW DRIFTS OVER CENTRAL ONTARIO.
WHILE THE GFS IS MORE PROGRESSIVE WITH THE FRONT...AND BUILDS COLD
HIGH PRESSURE BACK INTO WESTERN AND CENTRAL LAKE SUPERIOR ON
SUNDAY...THE ECMWF HOLDS ONTO THE SFC TROUGH A BIT LONGER. THE
DIFFERENCE SHOWS UP WELL ON THE 850MB CHART...WITH TEMPS OF -14C AT
18Z SUNDAY OFF THE GFS...WHILE THE ECMWF STILL HAS READINGS AROUND
-4C...AND KEEPS ANY COOLER READINGS BELOW -10C TO LATE SUNDAY NIGHT
AND BEYOND. THE 500MB TROUGH SHOULD PUSH EAST INTO THE LOWER GREAT
LAKES AND EASTERN ONTARIO ON MONDAY...WITH NORTHWESTERLY FLOW
REMAINING ALOFT THROUGH AT LEAST TUESDAY. ON A SIDE NOTE...THE
00Z/26 RUN OF THE ECMWF SIGNIFICANTLY INTENSIFIED THE SOUTHERN EDGE
OF THE TROUGH ROTTING THROUGH THE AREA SUNDAY NIGHT. THIS WOULD
RESULT IN A BETTER CHANCE OF PRECIPITATION...AND MUCH STRONGER
WINDS. AT 12Z MONDAY THE 12Z/25 RUN HAD WINDS OF UP TO 25KTS AT
850MB. THE LATEST RUN...WITH A SECONDARY DEEPENING SFC LOW CROSSING
CENTRAL AND EASTERN UPPER MICHIGAN SUNDAY NIGHT ALLOWS FOR A 45-60KT
850MB LLJ TO CROSS AT 12Z MONDAY. WILL BE INTERESTING IF THE 12Z RUN
LATER TODAY KEEPS UP THIS TREND...BUT FOR NOW WILL KEEP IT OUT OF
THE ONGOING FORECAST...WITH NO GALES OVER THE LAKE EXPECTED QUITE
YET.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 143 AM EDT TUE MAR 26 2013
ALTHOUGH SOME NEAR SFC DRY AIR HAS SLOWED THE PROCESS A BIT...EXPECT
CONDITIONS AT ALL 3 SITES TO TREND TOWARD MVFR AS A DISTURBANCE/
MOISTER AIR ARRIVES EARLY THIS MRNG IN THE PRESENCE OF UPSLOPE CYC
NLY FLOW. THE SOMEWHAT LOWER CONDITIONS ALONG WITH THE THREAT OF
SOME -SHSN/-FZDZ ARE MOST LIKELY AT IWD/SAW...WHERE THE LLVL FLOW
PRESENTS A GREATER UPSLOPE WIND COMPONENT. PASSAGE OF DISTURBANCE
AND DIURNAL HEATING ON TUE AFTN SHOULD ALLOW SOME IMPROVEMENT TO HI
END MVFR/LO END VFR CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 513 AM EDT TUE MAR 26 2013
HIGH PRESSURE OVER THE PLAINS WILL ONLY SLOWLY BUILD TO THE EAST
TODAY INTO WEDNESDAY KEEPING NORTHERLY WINDS IN THE 15 TO 25 KNOT
RANGE OVER THE EAST HALF OF THE LAKE AND IN THE 10 TO 15 KNOT RANGE
OVER THE WEST. AS THE HIGH BUILDS INTO THE WESTERN GREAT LAKES FROM
WED NIGHT INTO FRIDAY WINDS WILL BE RELATIVELY LIGHT...GENERALLY
BELOW 20 KNOTS. AS THE RIDGE SHIFTS TO THE EAST OF THE AREA
SATURDAY...LIGHT TO MODERATE S TO SW WINDS WILL DEVELOP.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...KC
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
413 AM EDT TUE MAR 26 2013
.UPDATE...
ISSUED AT 952 PM EDT MON MAR 25 2013
BASED ON LOCAL 00Z RAOBS...WHICH SHOW INVERTED V T/TD PROFILES
THRU ABOUT H85 CONSISTENT WITH INCRSG SOLAR ANGLE/DAYTIME HEATING...
LOWERED POPS/REMOVED FZDZ THRU ABOUT 06Z. STILL LOOKING FOR
COMBINATION OF ARRIVAL OF DEEPER MSTR/SHRTWV FM THE NE ALONG WITH
SOME ACCOMPANYING DEEP LYR QVECTOR CNVGC IN THE PRESENCE OF
NOCTURNAL COOLING AND PERSISTENT CYC LLVL NNE FLOW TO GENERATE SOME
-SHSN OVERNGT IN SPITE OF MARGINAL H85 TEMPS FOR LES. SINCE FCST
PROFILES FM MOST GUIDANCE STILL SHOW BULK OF UVV FOCUSED IN THE
LLVLS/UPSLOPE FORCING AND BLO THE DGZ...RETAINED MENTION OF FZDZ.
BUT DID CUT BACK TO PATCHY BASED ON SOMEWHAT HIER SFC DEWPT
DEPRESSIONS/DRIER LLVL AIR.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 356 PM EDT MON MAR 25 2013
...CHALLENGING FORECAST IN STORE THIS AFTERNOON THROUGH TUESDAY...
BROAD CYCLONIC FLOW IS PROGGED TO LINGER OVER MUCH OF THE GREAT
LAKES REGION THIS AFTERNOON THROUGH MUCH OF THE DAY TUESDAY AS A LOW
PRESSURE SYSTEM SLOWLY SHIFTS FROM THE OHIO VALLEY THIS
NORTHEASTWARD TOWARD THE NEW ENGLAND AREA. RADAR IS SHOWING SEVERAL
RETURNS NEAR LAKE SUPERIOR. SURFACE OBSERVATIONS AND WEBCAMS
INDICATE THAT THIS PRECIPITATION IS A MIX OF LIGHT FREEZING RAIN AS
WELL AS LIGHT SNOW SHOWERS. THE MAIN ISSUE FOR THE DAY INTO THE
NIGHT WILL BE PRECIPITATION TYPE AS SOUNDINGS SHOW ONLY MARGINAL
SUPPORT FOR SNOW DEVELOPMENT WITH THE TOP OF THE MOIST LAYER
REACHING AROUND -10C THROUGH MID MORNING. RUC AND NAM SOUNDING
INDICATE SLIGHTLY COOLER AIR...AROUND 12C...MOVING IN NEAR THE TOP
OF THE MOIST LAYER DURING THE AFTERNOON HOURS. THIS MAY TRANSITION
THE FZDZ OVER TO MORE OF A LIGHT SNOW AND FZDZ MIX OR TRANSITION
OVER TO ALL SNOW. AROUND 00Z SOUNDINGS WARM SLIGHTLY ALOFT AHEAD OF
THE NEXT 500MB TROUGH ROTATING INTO THE AREA. THIS WILL ALLOW THE
PRECIPITATION TO TRANSITION BACK TO A -FZDZ/-SHSN MIX...WHICH WILL
LAST THROUGH MID AFTERNOON BEFORE SLOWLY TAPERING OFF. CONFIDENCE
LEVEL IN ANY ONE TYPE OF PRECIPITATION IS LOW AS TEMPS ALOFT ARE
HUGGING THE -12C ISOTHERM WHICH IS WHERE ICE IS INTRODUCED INTO THE
CLOUD...THEREFORE HAVE KEPT A MIX OF FZDZ AND -SHSN IN THE FORECAST.
DELTA T VALUES ARE EXPECTED TO BE AROUND -12 TO -14 ALONG WITH MOIST
LOW LEVEL PROFILES WHICH WILL CONTINUE TO SUPPORT LAKE EFFECT
PRECIPITATION...WHICH MAY BE ENHANCED FURTHER OVERNIGHT AS THE
TROUGH PASSES DIRECTLY OVERHEAD. THERE IS ALSO AN UPSLOPE COMPONENT
WHICH MAY HELP FOCUS THE PRECIPITATION OVER THE HIGHER
TERRAIN...ESPECIALLY IN NORTH CENTRAL LOCATIONS AS WELL AS OVER THE
KEWEENAW.
TUESDAY...LAKE EFFECT SHSN AND FZDZ WILL LIKELY LINGER THROUGH THE
MID TO LATE MORNING HOURS BEFORE THE 500MB TROUGH SHIFTS TO THE
SOUTH OF THE UPPER PENINSULA. THIS WILL ALLOW SURFACE TO 850 DELTA T
VALUES TO BE AROUND -8C TO -9C...EFFECTIVELY REDUCING THE LAKE
EFFECT PRECIPITATION. SCATTERED FZDZ MAY LINGER OVER THE HIGH
TERRAIN IN CENTRAL UPPER MI AS A SIGNIFICANT AMOUNT OF LOW LEVEL
MOISTURE REMAINS IN PLACE AND UPSLOPE NORTH TO NORTH-NORTHWEST FLOW
CONTINUES TO MOVE FROM LAKE SUPERIOR INLAND.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 410 AM EDT TUE MAR 26 2013
LINGERING LOW LEVEL MOISTURE ROTATING IN FROM THE NORTH WILL BE
SLOWLY DIMINISHING WITH MUCH OF THE REMAINING FREEZING DRIZZLE AND
LIGHT SNOW SHOWERS/FLURRIES ENDING FOR THE MOST PART ON WEDNESDAY.
MOISTURE WILL BE TRAPPED BELOW 800MB WEDNESDAY MORNING AND FALL
AROUND OR BELOW 900MB BY WEDNESDAY EVENING...UNDER THE STRENGTHENING
INVERSION. WHILE THE MODELS DO SPIT OUT AROUND 0.01IN OR LESS
WEDNESDAY NIGHT AND THURSDAY...SIGNIFICANT PRECIP IS NOT ANTICIPATED.
THE STEADILY WARMING AFTERNOON HIGH TEMPERATURES WILL CONTINUE AS
THE 500MB HIGH OVER HUDSON BAY ON TUESDAY SINKS INTO ONTARIO AND
COMBINES WITH THE RIDGE ALREADY SET UP ACROSS THE WESTERN HALF OF
THE UNITED STATES. 850MB TEMPS AROUND -11C WEDNESDAY MORNING WILL
WARM TO -6C BY 12Z THURSDAY ON CONTINUED NORTHERLY WINDS...AND
REMAIN NEARLY STEADY THROUGH FRIDAY AFTERNOON.
A WEAK SHORTWAVE WILL SWING IN ON THE NORTHWESTERLY FLOW ALOFT
THURSDAY NIGHT INTO EARLY FRIDAY...WITH LITTLE INFLUENCE ON OUR
WEATHER. THE WRAPPED UP 500MB LOW ENCOMPASSING MUCH OF CENTRAL
CANADA FROM MID WEEK ON WILL DIG A TROUGH ACROSS THE NORTHERN PLAINS
FRIDAY NIGHT INTO SATURDAY...AND EXTEND TO THE UPPER GREAT LAKES
FROM SATURDAY THROUGH AT LEAST MONDAY. TIMING AND STRENGTH OF THE
ASSOCIATED COLD FRONT IS STILL IN QUESTION...BUT IT LOOKS LIKE IT
SHOULD BE OVER FAR WESTERN LAKE SUPERIOR SATURDAY AFTERNOON...AND
SLOWLY TRANSITION ACROSS CENTRAL AND EASTERN LAKE SUPERIOR SATURDAY
NIGHT...AS THE SFC LOW DRIFTS OVER CENTRAL ONTARIO.
WHILE THE GFS IS MORE PROGRESSIVE WITH THE FRONT...AND BUILDS COLD
HIGH PRESSURE BACK INTO WESTERN AND CENTRAL LAKE SUPERIOR ON
SUNDAY...THE ECMWF HOLDS ONTO THE SFC TROUGH A BIT LONGER. THE
DIFFERENCE SHOWS UP WELL ON THE 850MB CHART...WITH TEMPS OF -14C AT
18Z SUNDAY OFF THE GFS...WHILE THE ECMWF STILL HAS READINGS AROUND
-4C...AND KEEPS ANY COOLER READINGS BELOW -10C TO LATE SUNDAY NIGHT
AND BEYOND. THE 500MB TROUGH SHOULD PUSH EAST INTO THE LOWER GREAT
LAKES AND EASTERN ONTARIO ON MONDAY...WITH NORTHWESTERLY FLOW
REMAINING ALOFT THROUGH AT LEAST TUESDAY. ON A SIDE NOTE...THE
00Z/26 RUN OF THE ECMWF SIGNIFICANTLY INTENSIFIED THE SOUTHERN EDGE
OF THE TROUGH ROTTING THROUGH THE AREA SUNDAY NIGHT. THIS WOULD
RESULT IN A BETTER CHANCE OF PRECIPITATION...AND MUCH STRONGER
WINDS. AT 12Z MONDAY THE 12Z/25 RUN HAD WINDS OF UP TO 25KTS AT
850MB. THE LATEST RUN...WITH A SECONDARY DEEPENING SFC LOW CROSSING
CENTRAL AND EASTERN UPPER MICHIGAN SUNDAY NIGHT ALLOWS FOR A 45-60KT
850MB LLJ TO CROSS AT 12Z MONDAY. WILL BE INTERESTING IF THE 12Z RUN
LATER TODAY KEEPS UP THIS TREND...BUT FOR NOW WILL KEEP IT OUT OF
THE ONGOING FORECAST...WITH NO GALES OVER THE LAKE EXPECTED QUITE
YET.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 143 AM EDT TUE MAR 26 2013
ALTHOUGH SOME NEAR SFC DRY AIR HAS SLOWED THE PROCESS A BIT...EXPECT
CONDITIONS AT ALL 3 SITES TO TREND TOWARD MVFR AS A DISTURBANCE/
MOISTER AIR ARRIVES EARLY THIS MRNG IN THE PRESENCE OF UPSLOPE CYC
NLY FLOW. THE SOMEWHAT LOWER CONDITIONS ALONG WITH THE THREAT OF
SOME -SHSN/-FZDZ ARE MOST LIKELY AT IWD/SAW...WHERE THE LLVL FLOW
PRESENTS A GREATER UPSLOPE WIND COMPONENT. PASSAGE OF DISTURBANCE
AND DIURNAL HEATING ON TUE AFTN SHOULD ALLOW SOME IMPROVEMENT TO HI
END MVFR/LO END VFR CONDITIONS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 356 PM EDT MON MAR 25 2013
HIGH PRESSURE IN PLACE OVER THE NORTHERN PLAINS AND LOW PRESSURE
SHIFTING EASTWARD FROM THE OHIO VALLEY TO EASTER SEABOARD WILL LEAD
TO A TIGHT PRESSURE GRADIENT OVER LAKE SUPERIOR THROUGH TUESDAY.
THIS WILL RESULT IN NORTHERLY TO NORTHWESTERLY WINDS 15 TO 25 KNOTS.
BEYOND TUESDAY AFTERNOON...HIGH PRESSURE WILL BUILD INTO THE UPPER
GREAT LAKES REGION KEEPING WINDS GENERALLY BELOW 20 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KC
SHORT TERM...KEC
LONG TERM...KF
AVIATION...KC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
143 AM EDT TUE MAR 26 2013
.UPDATE...
ISSUED AT 952 PM EDT MON MAR 25 2013
BASED ON LOCAL 00Z RAOBS...WHICH SHOW INVERTED V T/TD PROFILES
THRU ABOUT H85 CONSISTENT WITH INCRSG SOLAR ANGLE/DAYTIME HEATING...
LOWERED POPS/REMOVED FZDZ THRU ABOUT 06Z. STILL LOOKING FOR
COMBINATION OF ARRIVAL OF DEEPER MSTR/SHRTWV FM THE NE ALONG WITH
SOME ACCOMPANYING DEEP LYR QVECTOR CNVGC IN THE PRESENCE OF
NOCTURNAL COOLING AND PERSISTENT CYC LLVL NNE FLOW TO GENERATE SOME
-SHSN OVERNGT IN SPITE OF MARGINAL H85 TEMPS FOR LES. SINCE FCST
PROFILES FM MOST GUIDANCE STILL SHOW BULK OF UVV FOCUSED IN THE
LLVLS/UPSLOPE FORCING AND BLO THE DGZ...RETAINED MENTION OF FZDZ.
BUT DID CUT BACK TO PATCHY BASED ON SOMEWHAT HIER SFC DEWPT
DEPRESSIONS/DRIER LLVL AIR.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 356 PM EDT MON MAR 25 2013
...CHALLENGING FORECAST IN STORE THIS AFTERNOON THROUGH TUESDAY...
BROAD CYCLONIC FLOW IS PROGGED TO LINGER OVER MUCH OF THE GREAT
LAKES REGION THIS AFTERNOON THROUGH MUCH OF THE DAY TUESDAY AS A LOW
PRESSURE SYSTEM SLOWLY SHIFTS FROM THE OHIO VALLEY THIS
NORTHEASTWARD TOWARD THE NEW ENGLAND AREA. RADAR IS SHOWING SEVERAL
RETURNS NEAR LAKE SUPERIOR. SURFACE OBSERVATIONS AND WEBCAMS
INDICATE THAT THIS PRECIPITATION IS A MIX OF LIGHT FREEZING RAIN AS
WELL AS LIGHT SNOW SHOWERS. THE MAIN ISSUE FOR THE DAY INTO THE
NIGHT WILL BE PRECIPITATION TYPE AS SOUNDINGS SHOW ONLY MARGINAL
SUPPORT FOR SNOW DEVELOPMENT WITH THE TOP OF THE MOIST LAYER
REACHING AROUND -10C THROUGH MID MORNING. RUC AND NAM SOUNDING
INDICATE SLIGHTLY COOLER AIR...AROUND 12C...MOVING IN NEAR THE TOP
OF THE MOIST LAYER DURING THE AFTERNOON HOURS. THIS MAY TRANSITION
THE FZDZ OVER TO MORE OF A LIGHT SNOW AND FZDZ MIX OR TRANSITION
OVER TO ALL SNOW. AROUND 00Z SOUNDINGS WARM SLIGHTLY ALOFT AHEAD OF
THE NEXT 500MB TROUGH ROTATING INTO THE AREA. THIS WILL ALLOW THE
PRECIPITATION TO TRANSITION BACK TO A -FZDZ/-SHSN MIX...WHICH WILL
LAST THROUGH MID AFTERNOON BEFORE SLOWLY TAPERING OFF. CONFIDENCE
LEVEL IN ANY ONE TYPE OF PRECIPITATION IS LOW AS TEMPS ALOFT ARE
HUGGING THE -12C ISOTHERM WHICH IS WHERE ICE IS INTRODUCED INTO THE
CLOUD...THEREFORE HAVE KEPT A MIX OF FZDZ AND -SHSN IN THE FORECAST.
DELTA T VALUES ARE EXPECTED TO BE AROUND -12 TO -14 ALONG WITH MOIST
LOW LEVEL PROFILES WHICH WILL CONTINUE TO SUPPORT LAKE EFFECT
PRECIPITATION...WHICH MAY BE ENHANCED FURTHER OVERNIGHT AS THE
TROUGH PASSES DIRECTLY OVERHEAD. THERE IS ALSO AN UPSLOPE COMPONENT
WHICH MAY HELP FOCUS THE PRECIPITATION OVER THE HIGHER
TERRAIN...ESPECIALLY IN NORTH CENTRAL LOCATIONS AS WELL AS OVER THE
KEWEENAW.
TUESDAY...LAKE EFFECT SHSN AND FZDZ WILL LIKELY LINGER THROUGH THE
MID TO LATE MORNING HOURS BEFORE THE 500MB TROUGH SHIFTS TO THE
SOUTH OF THE UPPER PENINSULA. THIS WILL ALLOW SURFACE TO 850 DELTA T
VALUES TO BE AROUND -8C TO -9C...EFFECTIVELY REDUCING THE LAKE
EFFECT PRECIPITATION. SCATTERED FZDZ MAY LINGER OVER THE HIGH
TERRAIN IN CENTRAL UPPER MI AS A SIGNIFICANT AMOUNT OF LOW LEVEL
MOISTURE REMAINS IN PLACE AND UPSLOPE NORTH TO NORTH-NORTHWEST FLOW
CONTINUES TO MOVE FROM LAKE SUPERIOR INLAND.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 356 PM EDT MON MAR 25 2013
UPPER TROUGH THAT HAS BEEN INFLUENCING THE AREA OVER THE LAST
SEVERAL DAYS WILL BEGIN TO SHIFT EAST TUESDAY NIGHT INTO
WEDNESDAY...ALLOWING A WEAK UPPER RIDGE AND SURFACE HIGH PRESSURE TO
MOVE IN WEDNESDAY NIGHT AND REMAIN THROUGH FRIDAY.
LINGERING MOISTURE UNDER THE CYCLONIC FLOW FROM THE UPPER AND
SURFACE LOW OF THE NEW ENGLAND STATES WILL CONTINUE TO BRING THE
POTENTIAL FOR CLOUDS AND PRECIPITATION FOR TUESDAY NIGHT AND
WEDNESDAY. THIS WILL BE ESPECIALLY TRUE FOR LOCATIONS FAVORED BY
NORTH TO NORTHWEST WINDS. MODELS ARE FAIRLY PERSISTENT ON THE LOWER
LEVEL MOISTURE...925-850MB...BEING PRESENT FOR TUESDAY NIGHT INTO
WEDNESDAY MORNING WHILE A SURFACE TROUGH DROPS SOUTH ACROSS EASTERN
LAKE SUPERIOR. BEST CHANCES FOR PRECIPITATION LOOK TO BE ON TUESDAY
NIGHT INTO WEDNESDAY MORNING...BEFORE THE DEEPER MOISTURE DEPARTS
AND SUBSIDENCE FROM THE APPROACHING HIGH BEGINS TO INFLUENCE THE
CLOUD THICKNESS. WILL CONTINUE TO MENTION SLIGHT CHANCE AND A FEW
LOCALIZED CHANCE POPS FOR THE FAVORED NORTH-NORTHWEST LOCATIONS.
TYPE LOOKS TO BE A CONCERN AGAIN ON TUESDAY NIGHT INTO
WEDNESDAY...WITH CLOUD TOP TEMPERATURES BARELY RISING ABOVE -10C. AS
HAS BEEN THE CASE OVER THE LAST COUPLE OF DAYS...THE LIGHTER SHOWERS
WILL LIKELY BE FZDZ AND IF ANY STRONGER SHOWERS OCCUR THERE COULD BE
SNOW ASSOCIATED WITH IT. WILL LIMIT THE SNOW MENTION THOUGH...AS
CLOUD TOPS APPEAR TO BE A COUPLE DEGREES WARMER THAN THE LAST COUPLE
OF DAYS.
WEDNESDAY NIGHT INTO THURSDAY WILL BE THE TRANSITION PERIOD...AS THE
HIGH PRESSURE RIDGE MOVES OVER THE AREA FROM THE UPPER MISSISSIPPI
VALLEY AND THE RESIDUAL MOISTURE BECOMES FORCED BELOW 925MB. THIS
DOES LEAD TO SOME CONCERN FOR LOW CLOUDS BECOMING TRAPPED OVER THE
AREA ON WEDNESDAY NIGHT. SFC TO 925MB DELTA-T VALUES ARE ONLY AROUND
8-9C...SO LAKE INFLUENCE WILL BE BE LIMITED. BUT IF CLOUDS ARE STILL
PRESENT FROM WEDNESDAY...THE INCREASING SUBSIDENCE INVERSION AND
LACK OF MIXING DURING THE OVERNIGHT HOURS WILL TRY TO KEEP THEM IN
PLACE. THUS...WILL TRY TO HOLD ONTO MORE OF A PARTLY/MOSTLY CLOUDY
SKY FOR WEDNESDAY NIGHT AND THEN HAVE DAYTIME MIXING TRY TO REDUCE
CLOUDS SOMEWHAT ON THURSDAY. ONE THING TO WATCH ON THURSDAY WILL BE
THE INCREASING SFC-925MB LAPSE RATES IF BREAKS DO OCCUR. THIS COULD
LEAD TO DIURNAL CU REDEVELOPING OVER INTERIOR WEST LOCATIONS WHERE
LAPSE RATES APPROACH 9C/KM. WITH PLENTY OF DRY AIR...THURSDAY NIGHT
INTO FRIDAY SHOULD BE DRY AND PARTLY/MOSTLY CLEAR EVEN THOUGH A
SHORTWAVE MOVES ACROSS THE AREA IN THE NORTHWEST FLOW.
EXPECT GRADUAL WARMING TEMPERATURES THROUGH THE WEEK...ESPECIALLY
FOR THURSDAY AND FRIDAY WITH THE LATE MARCH SUNSHINE. WEDNESDAY
SHOULD SEE HIGHS IN THE MID-UPPER 30S AND THEN UPPER 30S THROUGH MID
40S FOR THURSDAY AND FRIDAY. 00Z ECMWF AND MOST OF IT/S ENSEMBLE
MEMBERS HAVE KSAW REACHING THE LOW 40S ON FRIDAY AND SATURDAY.
THUS...IT IS LOOKING LIKE OUR OFFICE WILL END UP REACHING 40 DEGREES
AND KEEP THIS MARCH FROM BEING THE FIRST MARCH ON RECORD WHERE WE
DIDN/T REACH 40 DEGREES.
CHANGES LOOK TO ARRIVE FOR THIS WEEKEND...AS A STRONG SHORTWAVE
DIVES SOUTHEAST THROUGH CENTRAL CANADA AND INTO THE UPPER GREAT
LAKES FOR LATE SATURDAY INTO SUNDAY. MODELS ARE FAIRLY CONSISTENT
ON THIS IDEA...WHICH INCREASES CONFIDENCE INTO THE FIRST PART OF
NEXT WEEK. AT THIS TIME...LOOKS LIKE ASSOCIATED COLD FRONT WILL
MOVE THROUGH ON SATURDAY AFTERNOON/NIGHT. BASED OFF THICKNESS AND
THERMAL PROFILES...LOOKS LIKE A MIX OF RAIN/SNOW AS THE FRONT MOVES
THROUGH. WITH THE DRY HIGH IN PLACE...QPF AMOUNTS LOOK TO BE
LIMITED AT THIS POINT WITH THE INITIAL FRONT. THEN BEHIND THE FRONT
ON SUNDAY...MAIN SHORTWAVE MOVES THROUGH AND COLDER 850MB TEMPS
SURGE SOUTHEAST AND REACH -12C/ECMWF OR -10C/GFS BY MONDAY MORNING.
WITH THE NORTHWEST FLOW GENERATED BY THE HIGH OVER THE NORTHERN
PLAINS...WOULD SOME LAKE EFFECT SNOW SHOWERS IN THE NORTHWEST
WIND FAVORED LOCATIONS FOR MONDAY. WILL TREND POPS UP SLIGHTLY FROM
A GENERAL MODEL CONSENSUS FOR THAT TIME FRAME NEAR LAKE SUPERIOR.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 143 AM EDT TUE MAR 26 2013
ALTHOUGH SOME NEAR SFC DRY AIR HAS SLOWED THE PROCESS A BIT...EXPECT
CONDITIONS AT ALL 3 SITES TO TREND TOWARD MVFR AS A DISTURBANCE/
MOISTER AIR ARRIVES EARLY THIS MRNG IN THE PRESENCE OF UPSLOPE CYC
NLY FLOW. THE SOMEWHAT LOWER CONDITIONS ALONG WITH THE THREAT OF
SOME -SHSN/-FZDZ ARE MOST LIKELY AT IWD/SAW...WHERE THE LLVL FLOW
PRESENTS A GREATER UPSLOPE WIND COMPONENT. PASSAGE OF DISTURBANCE
AND DIURNAL HEATING ON TUE AFTN SHOULD ALLOW SOME IMPROVEMENT TO HI
END MVFR/LO END VFR CONDITIONS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 356 PM EDT MON MAR 25 2013
HIGH PRESSURE IN PLACE OVER THE NORTHERN PLAINS AND LOW PRESSURE
SHIFTING EASTWARD FROM THE OHIO VALLEY TO EASTER SEABOARD WILL LEAD
TO A TIGHT PRESSURE GRADIENT OVER LAKE SUPERIOR THROUGH TUESDAY.
THIS WILL RESULT IN NORTHERLY TO NORTHWESTERLY WINDS 15 TO 25 KNOTS.
BEYOND TUESDAY AFTERNOON...HIGH PRESSURE WILL BUILD INTO THE UPPER
GREAT LAKES REGION KEEPING WINDS GENERALLY BELOW 20 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KC
SHORT TERM...KEC
LONG TERM...SRF
AVIATION...KC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS TAUNTON MA
739 AM EDT TUE MAR 26 2013
.SYNOPSIS...
A DISTANT OCEAN STORM WILL MOVE FURTHER AWAY FROM THE REGION TODAY.
UPPER LEVEL LOW BACKING IN FROM THE WEST WILL BRING CLOUDS AND
SCATTERED RAIN/SNOW SHOWERS LATE WEDNESDAY AND THURSDAY. THE REST OF
THIS WEEK SHOULD BE DRY WITH TEMPERATURES CLOSE TO OR A LITTLE BELOW
NORMAL.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
7 AM UPDATE...
BULK OF SNOW/SLEET ASSOCIATED WITH THE MAIN LOW PRES WELL OFFSHORE
HAS MOVED AWAY FROM CAPE/ISLANDS IN THE LAST FEW HOURS. JUST A FEW
INTERIOR SNOW SHOWERS MOVING THROUGH THE REGION THIS MORNING INVOF
OF THE CONNECTICUT VALLEY. IT APPEARS THAT WITH UPPER LVL LOW
STILL GRADUALLY MOVING THROUGH SRN NEW ENGLAND EXPECT IT TO TAKE
SOME TIME FOR CLOUDS TO BREAK UP SAVE FOR EAST COASTAL LOCATIONS
TODAY. HAVE ADJUSTED TOWARD THE LATEST RAP WHICH SHOWS THIS TREND
WELL. OTHERWISE...HAVE UPDATED TEMPS/DWPTS AS WELL AS POPS AND WX
TO BETTER MATCH CURRENT TRENDS.
PREVIOUS DISCUSSION...
SCATTERED OCEAN EFFECT RAIN/SNOW SHOWERS ALONG WITH SOME SLEET
PELLETS ACROSS SOUTHEAST MA/RHODE ISLAND WILL BE WINDING DOWN EARLY
THIS MORNING. LITTLE IF ANY ACCUMULATIONS ARE ANTICIPATED.
OTHERWISE...GENERALLY A DRY DAY IS EXPECTED BUT WITH THE UPPER LEVEL
LOW LOCATED ACROSS NORTHERN NEW ENGLAND A SPOT SHOWER OR TWO WILL
REMAIN POSSIBLE INTO THE AFTERNOON. AREAL COVERAGE/DURATION OF
ANYTHING THAT DEVELOPS SHOULD BE QUITE LIMITED...SO WILL JUST COVER
IT WITH SLIGHT CHANCE POPS.
AN ABUNDANCE OF CLOUDS THIS MORNING SHOULD GIVE WAY TO SOME PARTIAL
SUNSHINE LATER THIS MORNING AND AFTERNOON...BUT STILL EXPECT AT
LEAST SCATTERED CUMULUS CLOUDS. HIGHS SHOULD RANGE FROM THE LOWER
TO MIDDLE 40S ACROSS THE HIGHER TERRAIN...TO THE UPPER 40S ACROSS
PORTIONS OF THE COASTAL PLAIN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
TONIGHT...
MOST OF THE DIURNAL CLOUDS SHOULD DISSIPATE ALONG WITH DIMINISHING
WINDS. THIS SHOULD ALLOW LOW TEMPS TO FALL INTO THE 20S...TO THE
LOWER 30S WITH DRY WEATHER EXPECTED.
WEDNESDAY... A PIECE OF UPPER LEVEL ENERGY WILL DROP SOUTH FROM
NORTHERN NEW ENGLAND. THIS WILL ALLOW FOR CLOUDS TO INCREASE FROM
THE NORTH THROUGH THE DAY ON WED. A FEW SPOT SHOWERS WILL ALSO BE
POSSIBLE...BUT THE VAST MAJORITY OF THE DAY WILL BE DRY IN A GIVEN
LOCATION. THEREFORE...JUST INCLUDED SLIGHT CHANCE POPS FOR NOW.
HIGH TEMPS WILL RANGE FROM THE MIDDLE 40S ACROSS THE HIGHER TERRAIN
AND FROM THE UPPER 40S TO AROUND 50 ON THE COASTAL PLAIN.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
OVERVIEW AND MODEL PREFERENCES...
26/00Z GUIDANCE IS IN FAIRLY GOOD AGREEMENT REGARDING THE
CONTINUATION OF STRONGLY BLOCKING PATTERN OVER WRN ATLANTIC AND
ERN CONUS. GIVEN THE BLOCKING...THE UPPER LVL LOW PRES ASSOCIATED
WITH THE SNOW/RAIN SHOWERS EARLY THIS MORNING WILL TAKE IT/S TIME
MOVING FURTHER OFFSHORE THROUGH THE WEEK. WITH MODELS IN DECENT
AGREEMENT THROUGH MUCH OF THIS WORK WEEK...WILL CONTINUE WITH THE
GFS/ECMWF BLEND SUPPORTED BY PREVIOUS LONG RANGE FORECASTERS. THE
ONLY CAVEAT HERE WILL THE POTENTIAL FOR A STRONGER LOW PRES AND
COLD FRONTAL SYSTEM FOR EARLY NEXT WEEK. AT THIS TIME...GIVEN THE
BLOCKED UPPER LVL FLOW...IT APPEARS THAT THE GFS MAY BE SHOWING
ITS TYPICAL FAST BIAS WITH THIS SYSTEM...SO WILL LEAN CLOSER TO
THE ECMWF TIMING...WHICH SUGGESTS PRECIPITATION IS MOST LIKELY
DURING THE DAY MON INTO MON NIGHT RATHER THAN SUN NIGHT INTO MON.
DETAILS...
WED NIGHT INTO THU NIGHT...
SLOW MOVING UPPER LVL LOW PRES WILL BE CONTINUING TO GRADUALLY
SHIFT TO THE E WITH TIME DURING THIS PERIOD. GIVEN THE MOISTURE
ASSOCIATED WITH THIS LOW...COMBINED WITH H5 TEMPERATURES DIPPING
TO SUB -30C...EXPECT MOSTLY UNSETTLED CONDITIONS TO CONTINUE WITH
A FAIR AMOUNT OF CLOUDS AND EVEN AN ISOLATED SHOWER OR TWO
POSSIBLE WED NIGHT INTO EARLY THU.
THU MID DAY INTO THU NIGHT...A STRONG SHORTWAVE WILL BE ROTATING
SW FROM THE MARITIMES. WHILE THIS WAVE WILL ACT AS THE KICKER TO
MOVE THE CUTOFF OFFSHORE...IT/S ASSOCIATED WITH A SFC COLD FRONT
WHICH WILL SWEEP FROM N TO S ACROSS THE REGION...ENHANCING LIFT
AND WORKING ON AVAILABLE MOISTURE. THEREFORE...WILL BE INCREASING
POPS DURING THIS PERIOD. P-TYPE WILL BE RELATED TO BOTH TIME OF
DAY AND PRECIPITATION INTENSITY. DURING THE DAY...HIGHER CHANCE
FOR RAIN UNLESS PRECIP RATES ARE HIGH ENOUGH TO FORCE A WETBULB
WITH DWPTS BELOW FREEZING SUPPORTING SOME SLEET/SNOW. ANY
LINGERING SHOWERS OVERNIGHT MAY BECOME MOSTLY SNOW/SLEET AS TEMPS
COOL. IN ANY CASE...QPF VALUES ARE EXPECTED TO BE BELOW 0.25
INCHES. TEMPERATURES GENERALLY JUST BELOW NORMAL THROUGH THE
PERIOD.
FRI INTO SUN...
MODEL GUIDANCE CONTINUES TO SUGGEST /WITH SUPPORT FROM CPC/ THAT
THE MID ATLANTIC /AND ERN CONUS/ BLOCKING PATTERN BEGINS TO BREAK
DOWN TOWARD THE BEGINNING OF APRIL. INITIALLY HIGH PRES WILL BE
BUILDING OVER THE REGION FROM THE W...WITH MOSTLY DRY CONDITIONS
AND H85 TEMPS RANGING FROM -2C TO ABOUT -5C WHICH WOULD YIELD
TEMPS CLOSE...TO POSSIBLY EVEN SLIGHTLY ABOVE NORMAL FOR LATE
MARCH AND EARLY APRIL. GUIDANCE DOES TRY TO PUSH ONE LAST
SHORTWAVE ASSOCIATED WITH THE CUTOFF THROUGH ON FRI...BUT IT WILL
BE A BALANCE AS TO WHETHER OR NOT DRY SUBSIDENCE CAN WIN OUT. FOR
NOW...WILL KEEP THE FORECAST MOSTLY DRY.
EARLY NEXT WEEK...
AT THIS TIME...IT STILL APPEARS THAT A STRONG WAVE AND ASSOCIATED
LOW PRES WILL PASS NW OF THE REGION DRAGGING A STRONG COLD FRONT
THROUGH THE REGION. USING THE ECMWF TIMING SUPPORTS PRECIPITATION
ONSET EARLY IN THE DAY MON...AND CONTINUING INTO EARLY MON NIGHT
FOLLOWED BY SOME COLDER TEMPERATURES THROUGH MID WEEK. WILL NEED
TO WATCH THIS...AS THERE DOES EXIST AT LEAST THE POTENTIAL FOR
SOME OCCASIONALLY HEAVY RAINFALL ASSOCIATED FRONTAL PASSAGE.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...HIGH CONFIDENCE THROUGH WEDNESDAY AFTERNOON.
MOSTLY VFR AT TAF SITES THIS MORNING SAVE FOR SOME ISOLATED MVFR
CIGS AND VSBYS ASSOCIATED WITH WEAK SNOW SHOWERS JUST E OF THE CT
VALLEY. THESE WILL REMAIN ISOLATED THROUGH THE MORNING.
OTHERWISE...MAINLY VFR CIGS IN SCATTERED TO BROKEN CUMULUS CLOUDS
THROUGH WED. BRIEF PERIODS OF MVFR CIGS ARE STILL POSSIBLE THROUGH
WED ALONG WITH A SPOT SHOWER OR TWO...BUT VFR CONDITIONS SHOULD
DOMINATE.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
WEDNESDAY NIGHT-THURSDAY...GENERALLY VFR. POTENTIAL FOR MVFR IN
SCATTERED SHOWERS. MODERATE CONFIDENCE.
FRIDAY AND SATURDAY...VFR. HIGH CONFIDENCE.
&&
.MARINE...
HIGH CONFIDENCE THROUGH WEDNESDAY AFTERNOON.
TODAY...NORTHERLY WINDS WILL CONTINUE TO SLOWLY DIMINISH TODAY AS
OCEAN STORM MOVES NORTHEAST AND FURTHER AWAY FROM THE REGION. WILL
CONTINUE GALE WARNINGS JUST FOR THE WATERS SOUTHEAST OF NANTUCKET
UNTIL 7 AM THIS MORNING. OTHERWISE...NORTHERLY WIND GUSTS WILL
SLOWLY DIMINISH BUT STILL REMAIN AT SCA THRESHOLDS INTO THE
AFTERNOON ACROSS THE OUTER-WATERS. SEAS WILL ONLY SLOWLY DIMINISH
LATER THIS MORNING AND AFTERNOON...REMAINING ABOVE SCA THRESHOLDS
ACROSS THE OUTER-WATERS THROUGH THE AFTERNOON.
TONIGHT AND WEDNESDAY...LEFT OVER NORTHEAST SWELL WILL RESULT IN SCA
SEAS LINGERING ACROSS THE EASTERN OUTER-WATERS INTO EARLY WED
MORNING. AFTER THAT TIME...WINDS/SEAS SHOULD BE BELOW SCA
THRESHOLDS OVER ALL OUR WATERS.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
WED NIGHT INTO THU NIGHT...MODERATE CONFIDENCE.
WINDS AND SEAS GRADUALLY INCREASE LATE WED NIGHT INTO THE DAY THU.
SEAS REACHING 5-7 FT OVER THE OUTER WATERS WITH WIND GUSTS AROUND
25 KT OVER ALL WATERS. SMALL CRAFT ADVISORIES LIKELY...BUT
CONDITIONS BEGIN TO SUBSIDE THU NIGHT.
FRI AND SAT...HIGH CONFIDENCE.
WINDS AND SEAS GENERALLY REMAIN BELOW SMALL CRAFT THRESHOLDS
THROUGH THE PERIOD AS HIGH PRES BUILDS OVER THE WATERS.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR
ANZ231>235-237.
SMALL CRAFT ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR ANZ250-254-
255.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ251.
SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ256.
&&
$$
SYNOPSIS...FRANK/DOODY
NEAR TERM...FRANK/DOODY
SHORT TERM...FRANK
LONG TERM...DOODY
AVIATION...FRANK/DOODY
MARINE...FRANK/DOODY
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1050 AM CDT TUE MAR 26 2013
.DISCUSSION...
ISSUED 1049 AM CDT TUE MAR 26 2013
MADE SOME MINOR ADJUSTMENTS TO THE FORECAST FOR SKY COVER AND
TWEAKED TEMPERATURES A BIT FOR THIS AFTERNOON. THE LATEST VISIBLE
SATELLITE SHOWING A CLEAR SKY ALONG AND WEST OF THE IL RIVER..WITH
PARTLY SUNNY CONDITIONS BETWEEN I-55 AND I-57 AND CLOUDY
CONDITIONS IN THE EAST AND SOUTHEAST. THE MODELS HAVE DONE A POOR
JOB OF FORECASTING THE LOW LEVEL MOISTURE FIELDS AND CLOUDS...WITH
THE EXCEPTION OF THE HRRR WHICH NAILED THE CLEARING TRENDS.
SATELLITE AND THE HRRR BOTH INDICATE THAT CLOUDS WILL ADVECT/FILL
BACK IN ACROSS WEST CENTRAL AND CENTRAL IL THIS AFTERNOON.
TEMPERATURES WILL BE TRICKY DUE TO SKY COVER FLUCTUATIONS AND SNOW
COVER...WHICH IS RAPIDLY DECREASING IN SOME AREAS DUE TO COMPACTION
...THE SUNSHINE AND CURRENT READINGS IN THE MID 30S. WILL
GENERALLY STICK TO A 35-40 RANGE FOR MOST AREAS THIS AFTERNOON.
WILL KEEP SCATTERED FLURRIES GOING FOR THE REST OF THE MORNING
INTO EARLY AFTERNOON IN EASTERN IL. NO RECENT REPORTS OF FLURRIES
HAVE BEEN RECEIVED...BUT RADAR INDICATED PATCHES EAST OF A CMI-
MTO-ROBINSON LINE.
MILLER
&&
.AVIATION...
ISSUED 655 AM CDT TUE MAR 26 2013
VFR CONDITIONS ARE EXPECTED TO CONTINUE ACROSS THE CENTRAL IL
TERMINAL AIRPORTS THROUGH 12Z/7 AM WED. BROKEN TO OVERCAST
CEILINGS OF 3.5-6K FT TO OCCUR INTO THIS EVENING...AND THEN SCATTERED
OUT FROM NW TO SE OVERNIGHT. FLURRIES SHOULD STAY NE OF I-74 TODAY
AND INTO INDIANA. CLEARING LINE WORKING ITS WAY SE INTO FAR NW IL
EARLY THIS MORNING...BUT EXPECT LOW CLOUDS TO FILL BACK IN LATER
THIS MORNING AND AFTERNOON BEFORE DECREASING AGAIN DURING TONIGHT.
NW WINDS 8-13 KTS TODAY TO DIMINISH TO 4-8 KTS THIS EVENING AND
LIGHT OVERNIGHT AS 1031 MB HIGH PRESSURE RIDGE OVER THE GREAT
PLAINS TO DRIFT EAST INTO THE MS VALLEY BY DAWN WED.
07
&&
.PREV DISCUSSION...
ISSUED 245 AM CDT TUE MAR 26 2013
SHORT TERM...TODAY THROUGH WEDNESDAY
MAIN TROF AXIS HAS SHIFTED SOUTH OF THE CWA WITH LINGERING
FLURRIES EXITING THE SE CWA EARLY THIS MORNING. PLENTY OF STRATOCU
OVERHEAD AND UPSTREAM AND WITH CYCLONIC LOW LEVEL FLOW CONTINUING
TODAY MOSTLY CLOUDY SKIES EXPECTED. SOME CLEARING NOTED ON IR SAT
IMAGERY OVER NRN IA/SRN MN SO SOME BREAKS FOR SUN CERTAINLY
POSSIBLE. LITTLE AIRMASS CHANGE FROM YESTERDAY AND HAVE HIGHS IN
THE MID/UPPER 30S. AN ELONGATED HIGH PRESSURE RIDGE WILL SHIFT EAST INTO
THE MISSISSIPPI VALLEY TONIGHT. IF SUBSIDENCE IS STRONG
ENOUGH TO PROVIDE SOME CLEARING LOW 20S OR EVEN SOME UPPER TEENS
LOWS POSSIBLE WITH SNOW COVER IN PLACE...HOWEVER FEEL CLOUDS MAY
HANG TOUGH WITH BETTER SUBSIDENCE TO OUR WEST SO WENT MORE
CONSERVATIVE LOW/MID 20S LOWS. BOTH NAM/GFS FORECAST SOUNDINGS
STILL SHOW MOISTURE TRAPPED BELOW A STRONG SUBSIDENCE INVERSION
UNDER THE IN-BUILDING RIDGE ON WEDNESDAY. SO WILL BE PESSIMISTIC
WITH CLEARING TRENDS THOUGH STRONGER LATE MARCH SUN COULD BREAK UP
THE CLOUDS FOR MORE OF A PARTLY SUNNY AFTERNOON. A GRADUAL WARMING
TREND WILL BEGIN AND MOST AREAS SHOULD SEE HIGHS IN THE LOWER 40S.
LONG TERM...THURSDAY THROUGH MONDAY
THE SURFACE RIDGE WILL BE THE DOMINANT FEATURE THROUGH THE END OF
THE WEEK AS IT GRADUALLY SHIFTS EAST INTO THE GREAT LAKES. SLOWLY
RISING HEIGHTS ALONG WITH SNOW MELT/MORE BARE GROUND WILL ALLOW
READINGS TO CLIMB A FEW DEGREES BOTH THU AND FRI. A DEVELOPING MID
LEVEL BAROCLINIC ZONE AND SFC WARM FRONT OVER THE MISSOURI
VALLEY...SHOULD KEEP ANY RAIN AND MOST OF THE CLOUD COVER WELL TO
OUR SOUTHWEST. BY SATURDAY THE HIGH SHIFTS EAST INTO THE
APPALACHIANS ALLOWING SOUTHERLY LLVL FLOW TO BRING EVEN WARMER AIR
INTO THE AREA WITH HIGHS EXPECTED INTO THE 50S. AN UPPER LEVEL
TROF MOVING INTO THE NORTHERN PLAINS WILL HELP DRIVE A COLD FRONT
INTO THE MIDWEST SATURDAY. 00Z GUIDANCE HAS SPED UP THE TIMING OF
THIS SYSTEM BY A SEVERAL HOURS...BUT MOST RAIN SHOULD BE ALONG AND
BEHIND THE FRONT. THUS HIGHEST RAIN CHANCES WILL BE SATURDAY NIGHT
AND SUNDAY MORNING. WITH LIMITED GULF MOISTURE ENTRAINED INTO THE
SYSTEM LIGHT AMOUNTS ARE EXPECTED. THE EXTENT OF THE COOL DOWN
BEHIND THIS FRONT IS IN QUESTION AS THE LONGER RANGE MODELS DIFFER
IN HOW FAR SOUTH THE SOUTHERN EXTENSION OF THE POLAR VORTEX DIGS
TOWARDS THE GREAT LAKES. MORE AGGRESSIVE GFS FAVORS A RETURN TO
WELL BELOW NORMAL TEMPS...WHILE THE ECMWF PUSHES THE BRUNT OF THE
COLD AIR OFF TO OUR NORTHEAST. FOR NOW WILL KEEP A BLENDED
FORECAST WITH TEMPS A FEW DEGREES BELOW NORMAL FOR THE BEGINNING
OF NEXT WEEK.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1017 AM EDT TUE MAR 26 2013
.UPDATE...
THE 12Z DTX SOUNDING SHOWED RATHER STEEP LAPSE RATES IN THE
900-700MB LAYER. BY AFTERNOON...DIURNAL HEATING WILL ONLY STEEPEN
THE LOW LEVEL LAPSE RATES. THE REGIONAL WATER VAPOR LOOP SHOWS A
WEAK MID LEVEL CIRCULATION OVER THE WESTERN GREAT LAKES. THIS
FEATURE WILL SPREAD SOME LARGE SCALE ASCENT ACROSS SE MI THROUGH
EARLY AFTERNOON. THE COMBINATION OF THE WEAK LARCE SCALE LIFT AND
INCREASING DIURNAL INSTABILITY WITHIN A REGION OF AMPLE MID LEVEL
MOISTURE OVER LOWER MI SHOULD SUPPORT FAIRLY GOOD COVERAGE OF
SHOWERS ACROSS A GOOD PORTION OF THE FORECAST AREA THIS AFTERNOON.
THIS WILL BE SUPPORTIVE OF A SLIGHT INCREASE IN POPS THIS
AFTERNOON. THE MORNING DTX SOUNDING ALSO SUGGESTED THAT AFTERNOON
MIXING WILL BOOST TEMPS INTO THE LOWER 40S. THIS LOOKS REASONABLE
GIVEN THERE HAVE BEEN SOME BREAKS IN THE CLOUDS AND GIVEN 10 AM
TEMPS ARE ALREADY IN THE MID-UPPER 30S. THIS SLIGHT UPWARD
ADJUSTMENT TO THE TEMPS /WHICH THE RAP SOUNDINGS SEEM TO HAVE A
BETTER HANDLE ON/ WOULD SUGGEST THAT THE DEPTH OF WARM AIR IN THE
BOUNDARY LAYER WOULD BE SUPPORTIVE OF MAINLY RAIN FOR AFTERNOON
PRECIP TYPE. GIVEN THE CONVECTIVE POTENTIAL...A CHANGE OVER TO
BRIEFLY HEAVY/WET SNOW WOULD STILL BE POSSIBLE. THUS WILL UPDATE
THE FORECAST TO INCREASE AFTERNOON TEMPS AND ADD A MIX OF
RAIN/SNOW TO THE PRECIP TYPE.
&&
.AVIATION...ISSUED 708 AM EDT TUE MAR 26 2013
//DISCUSSION...
A BROKEN HIGH VFR CEILING DURING THE MORNING WILL CARRY SOME SNOW
FLURRIES BEFORE FILLING IN AND FALLING UNDER 5000 FEET DURING THE
AFTERNOON. DAYTIME SURFACE HEATING UNDER THE COOL AIR MASS SUPPLIED
BY PERSISTENT NORTHWEST WIND WILL RESULT IN THE LOWER CLOUD COVER
AND POSSIBLY SCATTERED COVERAGE OF HEAVIER SNOW SHOWERS THROUGH
EARLY EVENING. AFTER THAT, THERE IS CAUTIOUS OPTIMISM THAT DRY AIR
FROM NORTHERN ONTARIO WILL HELP WITH A MODEST CLEARING TREND BY
MIDNIGHT THROUGH SUNRISE WEDNESDAY.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN CEILING BELOW 5000 FEET DURING THE AFTERNOON
AND EVENING.
&&
.PREV DISCUSSION...ISSUED 331 AM EDT TUE MAR 26 2013
SHORT TERM... TODAY AND TONIGHT
RADAR COMPOSITES INDICATE RESPECTABLE COVERAGE OF FLURRIES AND
CLUSTERS OF SNOW SHOWERS OVER LOWER MICHIGAN DURING THE EARLY
MORNING. THE 00Z SOUNDINGS FROM APX AND DTX INDICATE THIS LIGHT
ACTIVITY IS PRIMARILY A RESULT OF BROAD CYCLONIC LOW LEVEL FLOW
WORKING ON STEEP LAPSE RATES OF 7-8 C/KM BELOW 750 MB. CLUSTERS OF
SNOW SHOWERS SLIGHTLY ABOVE A FLURRY EMANATING FROM OVER LAKE HURON
ARE GETTING A BOOST FROM THE RELATIVELY WARM WATER BUT ARE JUST AN
EXTENSION OF ACTIVITY FROM UPSTREAM OVER NORTHERN ONTARIO RATHER
THAN LEGITIMATE LAKE EFFECT. SATELLITE IMAGERY ALSO INDICATES MID
LEVEL CIRCULATION WITHIN THE WEAK UPPER LEVEL TROUGH OVER THE
NORTHERN GREAT LAKES. THIS FEATURE WILL ADD SOME MID LEVEL COOLING
TO THE RATHER SUBSIDENT LOOKING 00Z APX SOUNDING AS THE TROUGH
SETTLES SOUTHWARD OVER LOWER MICHIGAN DURING THE DAY. ADD TO THAT A
COMPONENT OF DIURNAL SURFACE WARMING AND WE CAN EXPECT ONGOING
ACTIVITY TO CONTINUE IF NOT GROW IN COVERAGE BY LATE MORNING THROUGH
THE AFTERNOON. MODEL SOUNDINGS INDICATE THE ABOVE FREEZING LAYER
DEEPENING FROM THE SURFACE TO JUST ABOUT 800 FEET BY MID AFTERNOON
WHICH IS SHALLOW ENOUGH TO ALLOW SNOWFLAKES TO REACH THE SURFACE
WHERE THEY WILL MELT ON CONTACT WITH THE GROUND AS MAX TEMPS MAKE A
RUN TOWARD 40. GIVEN THE EXPECTATION OF ONLY TRACE AMOUNTS OF SNOW
AT ANY ONE LOCATION, THE INHERITED GENEROUS SCATTERED POP FORECAST
LOOKS FINE AND WILL BE CONTINUED IN THIS PACKAGE.
LEFTOVER DIURNALLY ENHANCED SNOW SHOWERS OR FLURRIES WILL LAST INTO
THE EVENING BUT WILL THEN GIVE WAY TO A CHALLENGING CLOUD FORECAST
FOR THE REST OF THE NIGHT. A SIZEABLE SLUG OF DRY AIR OVER WESTERN
QUEBEC/NE ONTARIO AT PRESS TIME WILL LIKELY HAVE A NEGATIVE
INFLUENCE ON THE POTENTIAL FOR STRATOCU MAINTENANCE OVER THE GREAT
LAKES LATER TONIGHT. THIS DRY AIR WILL WORK AGAINST CONTINUED BROAD
CYCLONIC FLOW THROUGH THE LOW LEVELS WITH ENOUGH COLD AIR BELOW 850
MB FOR SOME SIPHONING OF MOISTURE FROM THE LAKES. LOW LEVEL RH
FIELDS IN THE 00Z MODELS EXHIBIT THE USUAL HIGH BIAS IN MOISTURE
CONTENT WHICH MAKES IT A TOUGH CALL ON WHICH PROCESS WILL WIN OUT.
THE FORECAST WILL REFLECT CAUTIOUS OPTIMISM BY CUTTING CLOUD COVER
BELOW MODEL DEPICTIONS BUT STILL MAINTAIN SOME COVERAGE THROUGH
SUNRISE WEDNESDAY.
LONG TERM...WEDNESDAY THROUGH MONDAY
PV ANOMALY ASSOCIATED WITH THE NEWFOUNDLAND UPPER LOW IS STILL
PROGGED BY THE 00Z GUIDANCE TO ROTATE SOUTHWARD ACROSS THE EASTERN
GREAT LAKES LATE ON WEDNESDAY, BRINGING A GLANCING BLOW OF SHALLOW
FORCING FOR ASCENT TO SOUTHEAST MICHIGAN. ULTIMATELY MADE THE
DECISION TO REINTRODUCE POPS FOR LATE WEDNESDAY NIGHT OWING
PRIMARILY TO THE RESPECTABLE MOISTURE CONTENT THAT WILL BE
ASSOCIATED WITH THIS WAVE. 00Z NAM PLANVIEWS DEPICT OF 2 G/KG OF H20
AT H7 AND 3 G/KG AT H85. WHILE NOT PARTICULARLY IMPRESSIVE, THIS
WILL BE SUFFICIENT TO MAINTAIN SATURATION THROUGH ABOUT THE LOWEST
10KFT AND WILL ALSO PROVIDE A BRIEF WINDOW FOR ACTIVATION OF THE
DENDRITE GROWTH LAYER...AT LEAST THE LOWER REACHES OF IT. AS A
RESULT, POPS TAPERING FROM HIGH CHANCE IN THE EASTERN THUMB TO LOW
CHC ACROSS THE CENTRAL/SW CWA ARE NOW IN PLACE ALONG WITH
CATEGORICAL MENTION OF FLURRIES FOR ROUGHLY THE SAME AREA.
A STRONG SURGE OF PACIFIC JET ENERGY WILL DRIVE THE EVOLUTION OF THE
LARGE SCALE NOAM PATTERN FOR THE REMAINDER OF THE LONG TERM PERIOD.
WHAT THIS WILL MEAN LOCALLY IS THAT THE NEXT TWO DAYS WILL BE
CHARACTERIZED BY DECREASING INFLUENCE OF LARGE SCALE MOIST CYCLONIC
FLOW AND THUS INCREASED POTENTIAL TO SEE SOME SUN AND WARMING OF
TEMPERATURES BEGINNING ACROSS THE WEST ON THURSDAY. AS THE UPPER AIR
PATTERN IS PUSHED ALONG BY THE PAC JET, HIGH LATITUDE SHORTWAVE
RIDGING WILL DEAMPLIFY AND PROPAGATE ACROSS THE GREAT LAKES
THURS/FRI RESULTING IN A PATTERN OF RISING HEIGHTS AND A REBOUNDING
THERMAL FIELD. AREAS THAT SEE SUN ON THURSDAY, MOST LIKELY ACROSS
THE FAR WEST/SOUTHWEST WILL SEE TEMPERATURES JUMP INTO THE MID 40S,
WHILE THE REMAINDER OF SEMI WILL HAVE TO WAIT UNTIL FRIDAY WHEN MOST
OF THE AREA WILL SEE MID/UPPER 40S. ANOTHER ROUND OF SHORTWAVE
RIDGING LEADING A RENEWED SURGE OF DRY NW FLOW WILL KEEP THE AREA
DRY THROUGH AT LEAST THE FIRST HALF OF THE WEEKEND AND WILL FORCE
FURTHER WARMTH TO LIFT INTO THE STATE ALLOWING HIGHS TO CLIMB TO
AROUND 50.
THE APPROACH OF THE AFOREMENTIONED PAC JET SURGE WILL BE FELT
STRONGLY SUNDAY INTO MONDAY, FIRST WITH A PERIOD OF RAIN SHOWERS
ASSOCIATED WITH THE INITIAL ROUND OF HEIGHT FALLS ON SUNDAY AND THEN
WITH THE PASSAGE OF A VIGOROUS UPPER TROUGH AS THE JET DIVES OUT OF
NW FLOW ALOFT. MONDAY WILL THEN POTENTIALLY REPRESENT A TRANSITION
DAY THAT WILL SEE THE RETURN OF BELOW NORMAL TEMPERATURES/SNOW
CHANCES. SOLID RUN-TO-RUN CONTINUITY OF THE ECMWF ALONG WITH THE
HIGH AMPLITUDE NATURE OF THE TROUGH AND GRADUAL TREND TOWARD A MORE
VIGOROUS EVOLUTION ALL LEND HIGHER THAN NORMAL CONFIDENCE IN THE
GENERAL ASPECT OF A RETURN TO COOLER WEATHER EARLY NEXT WEEK.
MULTIPLE CYCLES OF THE GFS PROVIDING RESPECTABLE CONTINUITY LATE
THIS WEEKEND INTO EARLY NEXT WEEK PROVIDE AN ADDITIONAL BOOST IN
CONFIDENCE.
MARINE...
LAKE HURON AND LOWER MICHIGAN WILL REMAIN BETWEEN HIGH PRESSURE OVER
THE PLAINS AND LOW PRESSURE OFF THE NEW ENGLAND COAST THROUGH THE
MIDDLE PART OF THE WEEK. THIS WILL MAINTAIN A PERSISTENT NORTHWEST
WIND IN THE 10 TO 15 KNOT RANGE WITH GUSTS TO 20 KNOTS. THE WIND
FIELD WILL VARY IN STRENGTH DURING THIS TIME BUT OVERALL WILL FORCE
WAVES IN EXCESS OF 4 FEET OVER THE SOUTH HALF OF LAKE HURON AT LEAST
THROUGH WEDNESDAY NIGHT. HIGH PRESSURE WILL THEN BE ABLE TO MAKE
SOME EASTWARD PROGRESS INTO THE GREAT LAKES THURSDAY WHICH WILL HELP
IMPROVE MARINE CONDITIONS HEADING INTO THE WEEKEND.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
SANILAC...UNTIL 6 AM THURSDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......SC
AVIATION.....BT
SHORT TERM...BT
LONG TERM....JVC
MARINE.......BT
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
741 AM EDT TUE MAR 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 513 AM EDT TUE MAR 26 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A PERSISTENT BLOCKING RIDGE
FROM NRN CANADA INTO HUDSON BAY AND A TROUGH FROM THE CANADIAN
MARITIMES INTO NRN NEW ENGLAND RESULTING IN WEAK NE FLOW THROUGH THE
NRN GRREAT LAKES. AT THE SFC...NRLY FLOW PREVAILED ACROSS LAKE
SUPERIOR BETWEEN A TROUGH INTO THE ERN LAKES AND A RIDGE OVER THE
PLAINS. IR LOOP SHOWED THE BACK EDGE OF THE CLOUDS AND DEEPER
MOISTURE ADVANCING WESTWARD TOWARD THE E SIDE OF LAKE SUPERIOR.
RADAR INDICATED SCT SHSN INTO CNTRL UPPER MI WITH MORE CELLULAR THAN
BANDED PATTERN MORE TYPICAL OF LES. EVEN THOUGH 850 MB TEMPS TO NEAR
-10C ONLY PROVIDED MARGINAL OVER LAKE INSTABILITY...A WEAK SHORTWAVE
TROUGH AND ASSOCIATED 700-300 MB QVECTOR CONV HAS SUPPORTED SHSN
DEVELOPMENT. SNOW/WATER RATIO HAS INCREASED AND -FZDZ POTENTIAL
DIMINISHED WITH MOISTURE THROUGH THE DGZ.
TODAY...AS THE FORCING WITH THE SHRTWV SLIDES OFF TO THE SOUTHEAST
AND THE DEEPER MOISTURE DEPARTS...EXPECT THE SHSN TO QUICKLY
DIMINISH BY LATE MORNING. SO...ADDITIONAL SNOWFALL AMOUNTS OF ONLY A
HALF INCH OR LESS ARE EXPECTED. THERE MAY STILL BE A PERIOD WHERE
SOME -FZDZ IS POSSIBLE AS THE MOIST LAYER FALLS AT OR BELOW THE -10C
LEVEL. WITH DAYTIME HEATING AND GREATER MIXING...THERE MAY EVEN BE A
PERIOD OF SOME CLEARING INTO THE E HALF OF UPPER MI.
OTHERWISE...HIGH TEMPS WILL REMAIN BELOW NORMAL...IN THE LOWER TO
MID 30S.
TONIGHT...ANOTHER BATCH OF 925-850 MB MOISTURE IS EXPECTED TO MOVE
IN FROM THE NORTHEAST BRINGING THE POTENTIAL FOR ANOTHER ROUND OF
LAKE ENHANCED PCPN. SINCE TEMPS NEAR TO THE TOP OF THE MOIST LAYER
AT 850 MB ARE A BIT HIGHER...ONLY TO AROUND -8C...THERE MAY BE A
BETTER CHANCE FOR -FZDZ WITH ANY PCPN THAT DEVELOPS. WITH ONLY A
MODEST NRLY UPSLOPE WIND COMPONENT IN THE 20 TO 25 KNOT RANGE...ONLY
SLIGHT OR LOWER END CHANCE POPS WERE MENTIONED.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 410 AM EDT TUE MAR 26 2013
LINGERING LOW LEVEL MOISTURE ROTATING IN FROM THE NORTH WILL BE
SLOWLY DIMINISHING WITH MUCH OF THE REMAINING FREEZING DRIZZLE AND
LIGHT SNOW SHOWERS/FLURRIES ENDING FOR THE MOST PART ON WEDNESDAY.
MOISTURE WILL BE TRAPPED BELOW 800MB WEDNESDAY MORNING AND FALL
AROUND OR BELOW 900MB BY WEDNESDAY EVENING...UNDER THE STRENGTHENING
INVERSION. WHILE THE MODELS DO SPIT OUT AROUND 0.01IN OR LESS
WEDNESDAY NIGHT AND THURSDAY...SIGNIFICANT PRECIP IS NOT ANTICIPATED.
THE STEADILY WARMING AFTERNOON HIGH TEMPERATURES WILL CONTINUE AS
THE 500MB HIGH OVER HUDSON BAY ON TUESDAY SINKS INTO ONTARIO AND
COMBINES WITH THE RIDGE ALREADY SET UP ACROSS THE WESTERN HALF OF
THE UNITED STATES. 850MB TEMPS AROUND -11C WEDNESDAY MORNING WILL
WARM TO -6C BY 12Z THURSDAY ON CONTINUED NORTHERLY WINDS...AND
REMAIN NEARLY STEADY THROUGH FRIDAY AFTERNOON.
A WEAK SHORTWAVE WILL SWING IN ON THE NORTHWESTERLY FLOW ALOFT
THURSDAY NIGHT INTO EARLY FRIDAY...WITH LITTLE INFLUENCE ON OUR
WEATHER. THE WRAPPED UP 500MB LOW ENCOMPASSING MUCH OF CENTRAL
CANADA FROM MID WEEK ON WILL DIG A TROUGH ACROSS THE NORTHERN PLAINS
FRIDAY NIGHT INTO SATURDAY...AND EXTEND TO THE UPPER GREAT LAKES
FROM SATURDAY THROUGH AT LEAST MONDAY. TIMING AND STRENGTH OF THE
ASSOCIATED COLD FRONT IS STILL IN QUESTION...BUT IT LOOKS LIKE IT
SHOULD BE OVER FAR WESTERN LAKE SUPERIOR SATURDAY AFTERNOON...AND
SLOWLY TRANSITION ACROSS CENTRAL AND EASTERN LAKE SUPERIOR SATURDAY
NIGHT...AS THE SFC LOW DRIFTS OVER CENTRAL ONTARIO.
WHILE THE GFS IS MORE PROGRESSIVE WITH THE FRONT...AND BUILDS COLD
HIGH PRESSURE BACK INTO WESTERN AND CENTRAL LAKE SUPERIOR ON
SUNDAY...THE ECMWF HOLDS ONTO THE SFC TROUGH A BIT LONGER. THE
DIFFERENCE SHOWS UP WELL ON THE 850MB CHART...WITH TEMPS OF -14C AT
18Z SUNDAY OFF THE GFS...WHILE THE ECMWF STILL HAS READINGS AROUND
-4C...AND KEEPS ANY COOLER READINGS BELOW -10C TO LATE SUNDAY NIGHT
AND BEYOND. THE 500MB TROUGH SHOULD PUSH EAST INTO THE LOWER GREAT
LAKES AND EASTERN ONTARIO ON MONDAY...WITH NORTHWESTERLY FLOW
REMAINING ALOFT THROUGH AT LEAST TUESDAY. ON A SIDE NOTE...THE
00Z/26 RUN OF THE ECMWF SIGNIFICANTLY INTENSIFIED THE SOUTHERN EDGE
OF THE TROUGH ROTTING THROUGH THE AREA SUNDAY NIGHT. THIS WOULD
RESULT IN A BETTER CHANCE OF PRECIPITATION...AND MUCH STRONGER
WINDS. AT 12Z MONDAY THE 12Z/25 RUN HAD WINDS OF UP TO 25KTS AT
850MB. THE LATEST RUN...WITH A SECONDARY DEEPENING SFC LOW CROSSING
CENTRAL AND EASTERN UPPER MICHIGAN SUNDAY NIGHT ALLOWS FOR A 45-60KT
850MB LLJ TO CROSS AT 12Z MONDAY. WILL BE INTERESTING IF THE 12Z RUN
LATER TODAY KEEPS UP THIS TREND...BUT FOR NOW WILL KEEP IT OUT OF
THE ONGOING FORECAST...WITH NO GALES OVER THE LAKE EXPECTED QUITE
YET.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 739 AM EDT TUE MAR 26 2013
WHILE VFR CONDITIONS PREVAIL AT CMX/IWD...MVFR WILL PERSIST AT KSAW
UNTIL LATE THIS MORNING AS DRIER AIR MOVES IN FROM THE NORTHEAST.
SOME -FZDZ MAY ALSO BE POSSIBLE AS THE DEEPER MOISTURE DEPARTS THIS
MORNING. WITH INCREASED MIXING/DRYING INTO THE AFTERNOON CONDITIONS
SHOULD IMPROVE TO VFR. HOWEVER...WITH THE LOSS OF DAYTIME
HEATING/MIXING AND WITH ADDITIONAL LOW LEVEL MOISTURE MOVING IN FROM
THE NORTHEAST AND WEAK UPSLOPE FLOW...MVFR CIGS ARE EXPECTED AGAIN
TONIGHT AT ALL TAF SITES.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 513 AM EDT TUE MAR 26 2013
HIGH PRESSURE OVER THE PLAINS WILL ONLY SLOWLY BUILD TO THE EAST
TODAY INTO WEDNESDAY KEEPING NORTHERLY WINDS IN THE 15 TO 25 KNOT
RANGE OVER THE EAST HALF OF THE LAKE AND IN THE 10 TO 15 KNOT RANGE
OVER THE WEST. AS THE HIGH BUILDS INTO THE WESTERN GREAT LAKES FROM
WED NIGHT INTO FRIDAY WINDS WILL BE RELATIVELY LIGHT...GENERALLY
BELOW 20 KNOTS. AS THE RIDGE SHIFTS TO THE EAST OF THE AREA
SATURDAY...LIGHT TO MODERATE S TO SW WINDS WILL DEVELOP.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
915 AM EDT TUE MAR 26 2013
.SYNOPSIS...
LOW PRESSURE OFF THE NEW ENGLAND COAST WILL MOVE NORTHEAST TODAY
WHILE AN UPPER LEVEL DISTURBANCE MOVES ACROSS NORTH CAROLINA FROM
THE WEST THIS AFTERNOON AND EVENING. STRONG HIGH PRESSURE WILL BUILD
INTO THE AREA FROM THE WEST THROUGH FRIDAY. THE HIGH WILL BE OVER
THE AREA SATURDAY AND MOVE OFF OF THE COAST SUNDAY. A COLD FRONT
WILL APPROACH THE REGION MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 905 AM TUESDAY...ANOTHER CHILLY DAY IN STORE WITH MAX TEMPS
IN THE UPPER 40S TO LOWER 50S. LATEST RAP MODEL...ALONG WITH THE
EMC AND SPC 4 KM WRF MODELS AND NAM12 SHOW A FEW LIGHT SHOWERS OR
SPRINKLES WILL BE POSSIBLE OVER EASTERN NORTH CAROLINA THIS
AFTERNOON WITH STRONG H5 SHORTWAVE LINGERING JUST TO THE SOUTH OF
THE REGION. THE BEST CHANCE OF ANY MEASUREABLE PRECIP WILL BE IN
THE NORTHEAST AREAS BETWEEN THE SOUNDS. NO OTHER MAJOR CHANGES TO
THE FORECAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
AS OF 330 AM TUESDAY...SCT-BKN SCU WITH PSBL ISOLD SHOWERS WILL
LINGER INTO EARLY EVENING...THEN DECREASING CLOUDS EXPECTED WITH
LOSS OF HEATING. SECONDARY CAA SURGE FOLLOWING SHRT WV EXPECTED TO
PRODUCE ENOUGH WIND TO PRECLUDE DECOUPLING OVERNIGHT...BUT CONTINUED
SLIGHT COOLING OF AIR MASS WILL SUPPORT MIN TEMPS IN LOW-MID 30S
INLAND WITH UPR 30S OBX. NW HALF OF ONSLOW COUNTY...WHERE GROWING
SEASON IS IN EFFECT...COULD SEE LOWS AROUND 32...BUT WILL LET DAY
SHIFT TAKE A LOOK AT PSBL NEED FOR FREEZE WARNING THERE.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 3 AM TUE...A SLOW WARMING TREND IS IN STORE FOR THE EXTENDED
PERIOD DUE TO A STEADILY CHANGING SURFACE PATTERN. THE LARGE
CYCLONIC FLOW AROUND THE DEEP LOW FAR TO THE NORTHEAST WILL SLOWLY
BE REPLACED BY A SURFACE RIDGE BUILDING IN FROM THE WEST. THE HIGH
WILL BE CENTERED OVER THE AREA FRIDAY AND SATURDAY. THE HIGH WILL
MOVE OFF THE SOUTHEAST COAST SUNDAY. THE NEXT FRONT WILL APPROACH
FROM THE NORTHWEST MONDAY. HIGH TEMPS WEDNESDAY WILL BE IN THE
LOWER 50S...WARMING TO THE MID/UPPER 60S BY EARLY NEXT WEEK. ONLY
PRECIP IN THE FORECAST WILL BE A CHANCE OF SHOWERS SUNDAY NIGHT
AND MONDAY ASSOCIATED WITH THE APROACHING FRONT.
NOTE: GROWING SEASON WILL BEGIN ON WEDNESDAY FOR REST OF FORECAST
AREA...AND FREEZE WATCH/WARNING MAY BE NEEDED FOR INLAND SECTIONS
WED NIGHT/THU MORNING.
&&
.AVIATION /13Z TUESDAY THROUGH SATURDAY/...
SHORT TERM /THROUGH 12Z WEDNESDAY/...
AS OF 700 AM TUESDAY...VFR CONDITIONS EXPECTED THROUGH TAF PERIOD.
PTCHY SCU WILL AFFECT MAINLY KISO NEXT FEW HOURS...MOSTLY CLEAR
ELSEWHRE...THEN PERIOD OF BKN SCU CIGS AFTN INTO EVENING WITH SHRT
WV MOVING ACROSS...CLEARING OVERNIGHT. W-NW WINDS WITH GUSTS TO
AROUND 20 KT DURING THE DAY.
LONG TERM /WED THRU SAT/
AS OF 3 AM TUE...VFR WITH MOSTLY CLEAR SKIES AND A LIGHT NORTHWEST
FLOW THROUGH THE PERIOD.
&&
.MARINE...
SHORT TERM /THROUGH TONIGHT/...
AS OF 915 AM TUESDAY...GUSTY WNW WINDS CONTINUE ON THE COASTAL
WATERS AND SOUNDS WITH SEAS AS HIGH AS 7 FEET. NO CHANGES TO THE
ADVISORIES AT THIS TIME...BUT AS PORTIONS OF THE ADVISORY AREA
EXPIRE DURING THE LATE MORNING...WILL RE-EVALUATE THE ADVISORY.
LONG TERM /WED THRU SAT/
AS OF 3 AM TUE...LATEST RUN OF THE GFS AND ECMWF SHOWS THEM IN
GOOD AGREEMENT. USED A CONSENSUS BLEND FOR THE FORECAST. NORTHWEST
FLOW WILL CONTINUE OVER THE AREA. CYCLONIC FLOW AROUND DEEP LOW
FAR TO THE NORTHEAST WILL GRADUALLY GIVE WAY TO A SURFACE RIDGE
BUILDING IN FROM THE WEST THROUGH THE WEEKEND. WINDS AND SEAS
WILL SLOWLY SUBSIDE AS A RESULT.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR AMZ135-
156-158.
SMALL CRAFT ADVISORY UNTIL 2 PM EDT WEDNESDAY FOR AMZ150-152-
154.
&&
$$
SYNOPSIS...JBM
NEAR TERM...CTC
SHORT TERM...JBM
LONG TERM...HSA
AVIATION...JBM/HSA
MARINE...CTC/HSA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
633 AM EDT TUE MAR 26 2013
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL CONTINUE TO SEND PIECES OF JET ENERGY
ACROSS THE REGION THROUGH THURSDAY. HIGH PRESSURE WILL BUILD INTO
THE AREA FOR FRIDAY INTO SATURDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CURRENT FORECAST STILL LOOKS REASONABLE. HAVE ONLY MADE MINOR
TWEAKS TO TEMPERATURES TO REFLECT CURRENT CONDITIONS.
PREVIOUS DISCUSSION...
WARM ADVECTION IS OCCURRING AT 8H THIS MORNING ON NORTHERLY WINDS.
THIS MAKES IT DIFFICULT FOR THE LAKES TO CONTRIBUTE VERY MUCH
MOISTURE TO DEPOSIT ON NORTHERN OHIO. HOWEVER THERE MAY BE SOME
MIDDLE LEVEL FLURRIES OR MAYBE EVEN SOME SPRINKLES AS WE WARM INTO
THE MIDDLE TO UPPER 30S THIS AFTERNOON.
BY AFTERNOON INTO THE EVENING IT APPEARS THERE WILL BE ANOTHER
PIECE OF JET ENERGY MOVING THROUGH THE UPPER LEVEL TROUGH. THIS
SHOULD HELP TO INCREASE THE LIFT ACROSS THE REGION WITH AN
INCREASE IN LIGHT SNOW ANTICIPATED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
AS THE WAVE PASSES LATE TONIGHT INTO WEDNESDAY MORNING WE SHOULD
SEE SLIGHTLY COOLER AIR FLOW ACROSS LAKE ERIE. THIS MAY BE JUST
ENOUGH TO GET SOME LAKE EFFECT SNOW SHOWERS GOING...ESPECIALLY
WEDNESDAY EVENING INTO THURSDAY. ACCUMULATIONS WILL BE LIGHT BUT
MAY END UP BEING AN INCH OR 2 IN A FEW LOCATIONS TONIGHT AND
UP TO 3 INCHES IN THE SNOWBELT WEDNESDAY NIGHT. SINCE THE SUN
ANGLE HAS INCREASED IT WILL BE DIFFICULT SO SEE ANY SIGNIFICANT
ACCUMULATIONS DURING THE DAY.
DIURNAL TEMPERATURES WILL NOT VARY ALL THAT MUCH THROUGH THURSDAY
WITH HIGHS GENERALLY IN THE 30S AND LOWS FROM THE MID 20S TO LOWER
30S. HIGHS MAY GET BACK INTO THE 40S FOR MOST OF THE FORECAST AREA
ON FRIDAY.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HIGH PRESSURE WILL LINGER OVER THE OHIO VALLEY ON SATURDAY BEFORE
MOVING TO THE EAST COAST SATURDAY NIGHT. THE HIGH WILL BRING
SEASONAL TEMPERATURES AND DRY CONDITIONS FOR SATURDAY. TEMPERATURES
ON SUNDAY WILL BE SLIGHTLY WARMER THAN SATURDAY AS SOUTHERLY TO
SOUTHWESTERLY FLOW KICKS IN AHEAD OF AN APPROACHING COLD FRONT. THE
COLD FRONT WILL MOVE INTO THE AREA FROM THE NORTHWEST ON SUNDAY
AFTERNOON...WITH A DECENT CHANCE OF RAIN AHEAD AND ALONG THE FRONT.
PRECIPITATION WILL CONTINUE WELL INTO MONDAY AS A MOIST UPPER LEVEL
TROF LINGERS OVER THE AREA. SURFACE HIGH PRESSURE WILL MOVE INTO THE
AREA FROM THE WEST AGAIN ON TUESDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
HAD GOOD IMPROVEMENT FOR AVIATION THE PAST FEW HOURS WITH THE
IFR/MVFR EXITING WITH SOME DRYING COMING IN FROM THE NORTH. SO
QUESTION WILL BE WILL NON-VFR CONDITIONS RE-DEVELOP
OVERNIGHT/TOWARD MORNING. LATEST HRRR GUIDANCE IN PARTICULAR SHOW
THE NON VFR CEILINGS RETURNING TO THE EASTERN HALF OF THE AREA.
WITH LAMP GUIDANCE STILL SUGGESTING SOME IFR...HAVE INCLUDED THAT
IN A TEMPO FOR MFD/CAK. MAY GET SOME MVFR VBSY TO DEVELOP
TOO...VERY LOW LEVEL MOISTURE STICKS AROUND WITH ALL OF THE SNOW
ON THE GROUND. OVERALL A LOW CONFIDENCE FORECAST IN WHAT WILL
DEVELOP OVERNIGHT.
FOR TUESDAY ANOTHER TROUGH IN A SERIES WILL MOVE ACROSS NRN OH/NW
PA. THIS WILL BRING AN INCREASE IN SNOW SHOWER ACTIVITY...MOST
NOTABLY FOR THE EASTERN HALF OF THE AREA...BUT TOL/FDY MAY ALSO
SEE SOME LIGHT SNOW. THIS ARRIVES FOR THE AFTERNOON/EARLY EVENING.
.OUTLOOK...NON VFR IN -SHSN CONTINUING INTO THURSDAY.
&&
.MARINE...
HAVE ALLOWED THE SMALL CRAFT ADVISORY TO END. A COUPLE OF TROUGHS
WILL BRUSH THE LAKE...ONE THIS AFTERNOON AND THE OTHER ON WEDNESDAY
WITH SCATTERED SNOW SHOWERS. TODAY THE NORTHWEST WINDS WILL BECOME
MORE WNW AND FOR THE MOST PART STAY THAT WAY THROUGH THURSDAY WHEN
HIGH PRESSURE FINALLY BEGINS TO BUILD OVER THE REGION. WINDS COME UP
SOME ON WEDNESDAY...BUT THIS SHOULD STAY UNDER SMALL CRAFT ADV. HIGH
PRESSURE AND LIGHT/VARIABLE WINDS FOR FRIDAY AND SATURDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MULLEN
NEAR TERM...MULLEN
SHORT TERM...MULLEN
LONG TERM...YEAGER
AVIATION...OUDEMAN
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
359 AM EDT TUE MAR 26 2013
.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL CONTINUE TO SEND PIECES OF JET ENERGY
ACROSS THE REGION THROUGH THURSDAY. HIGH PRESSURE WILL BUILD INTO
THE AREA FOR FRIDAY INTO SATURDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WARM ADVECTION IS OCCURRING AT 8H THIS MORNING ON NORTHERLY WINDS.
THIS MAKES IT DIFFICULT FOR THE LAKES TO CONTRIBUTE VERY MUCH
MOISTURE TO DEPOSIT ON NORTHERN OHIO. HOWEVER THERE MAY BE SOME
MIDDLE LEVEL FLURRIES OR MAYBE EVEN SOME SPRINKLES AS WE WARM INTO
THE MIDDLE TO UPPER 30S THIS AFTERNOON.
BY AFTERNOON INTO THE EVENING IT APPEARS THERE WILL BE ANOTHER
PIECE OF JET ENERGY MOVING THROUGH THE UPPER LEVEL TROUGH. THIS
SHOULD HELP TO INCREASE THE LIFT ACROSS THE REGION WITH AN
INCREASE IN LIGHT SNOW ANTICIPATED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
AS THE WAVE PASSES LATE TONIGHT INTO WEDNESDAY MORNING WE SHOULD
SEE SLIGHTLY COOLER AIR FLOW ACROSS LAKE ERIE. THIS MAY BE JUST
ENOUGH TO GET SOME LAKE EFFECT SNOW SHOWERS GOING...ESPECIALLY
WEDNESDAY EVENING INTO THURSDAY. ACCUMULATIONS WILL BE LIGHT BUT
MAY END UP BEING AN INCH OR 2 IN A FEW LOCATIONS TONIGHT AND
UP TO 3 INCHES IN THE SNOWBELT WEDNESDAY NIGHT. SINCE THE SUN
ANGLE HAS INCREASED IT WILL BE DIFFICULT SO SEE ANY SIGNIFICANT
ACCUMULATIONS DURING THE DAY.
DIURNAL TEMPERATURES WILL NOT VARY ALL THAT MUCH THROUGH THURSDAY
WITH HIGHS GENERALLY IN THE 30S AND LOWS FROM THE MID 20S TO LOWER
30S. HIGHS MAY GET BACK INTO THE 40S FOR MOST OF THE FORECAST AREA
ON FRIDAY.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HIGH PRESSURE WILL LINGER OVER THE OHIO VALLEY ON SATURDAY BEFORE
MOVING TO THE EAST COAST SATURDAY NIGHT. THE HIGH WILL BRING
SEASONAL TEMPERATURES AND DRY CONDITIONS FOR SATURDAY. TEMPERATURES
ON SUNDAY WILL BE SLIGHTLY WARMER THAN SATURDAY AS SOUTHERLY TO
SOUTHWESTERLY FLOW KICKS IN AHEAD OF AN APPROACHING COLD FRONT. THE
COLD FRONT WILL MOVE INTO THE AREA FROM THE NORTHWEST ON SUNDAY
AFTERNOON...WITH A DECENT CHANCE OF RAIN AHEAD AND ALONG THE FRONT.
PRECIPITATION WILL CONTINUE WELL INTO MONDAY AS A MOIST UPPER LEVEL
TROF LINGERS OVER THE AREA. SURFACE HIGH PRESSURE WILL MOVE INTO THE
AREA FROM THE WEST AGAIN ON TUESDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
HAVE HAD GOOD IMPROVEMENT FOR AVIATION THE PAST FEW HOURS WITH
THE IFR/MVFR EXITING WITH SOME DRYING COMING IN FROM THE NORTH. SO
QUESTION WILL BE WILL NON-VFR CONDITIONS RE-DEVELOP
OVERNIGHT/TOWARD MORNING. LATEST HRRR GUIDANCE IN PARTICULAR SHOW
THE NON VFR CEILINGS RETURNING TO THE EASTERN HALF OF THE AREA.
WITH LAMP GUIDANCE STILL SUGGESTING SOME IFR...HAVE INCLUDED THAT
IN A TEMPO FOR MFD/CAK. MAY GET SOME MVFR VBSY TO DEVELOP
TOO...VERY LOW LEVEL MOISTURE STICKS AROUND WITH ALL OF THE SNOW
ON THE GROUND. OVERALL A LOW CONFIDENCE FORECAST IN WHAT WILL
DEVELOP OVERNIGHT.
FOR TUESDAY ANOTHER TROUGH IN A SERIES WILL MOVE ACROSS NRN OH/NW
PA. THIS WILL BRING AN INCREASE IN SNOW SHOWER ACTIVITY...MOST
NOTABLY FOR THE EASTERN HALF OF THE AREA...BUT TOL/FDY MAY ALSO
SEE SOME LIGHT SNOW. THIS ARRIVES FOR THE AFTERNOON/EARLY EVENING.
.OUTLOOK...NON VFR IN -SHSN CONTINUING INTO THURSDAY.
&&
.MARINE...
HAVE ALLOWED THE SMALL CRAFT ADVISORY TO END. A COUPLE OF TROUGHS
WILL BRUSH THE LAKE...ONE THIS AFTERNOON AND THE OTHER ON WEDNESDAY
WITH SCATTERED SNOW SHOWERS. TODAY THE NORTHWEST WINDS WILL BECOME
MORE WNW AND FOR THE MOST PART STAY THAT WAY THROUGH THURSDAY WHEN
HIGH PRESSURE FINALLY BEGINS TO BUILD OVER THE REGION. WINDS COME UP
SOME ON WEDNESDAY...BUT THIS SHOULD STAY UNDER SMALL CRAFT ADV. HIGH
PRESSURE AND LIGHT/VARIABLE WINDS FOR FRIDAY AND SATURDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT EARLY THIS MORNING FOR
LEZ142>149.
&&
$$
SYNOPSIS...MULLEN
NEAR TERM...MULLEN
SHORT TERM...MULLEN
LONG TERM...YEAGER
AVIATION...OUDEMAN
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
145 AM EDT TUE MAR 26 2013
.SYNOPSIS...
THE LOW THAT WAS OVER WESTERN PENNSYLVANIA WAS WEAKENING AND THE LOW
OFF THE MID ATLANTIC COAST WAS BECOMING PREDOMINATE. AN UPPER
LEVEL TROUGH WILL LINGER ACROSS THE EASTERN GREAT LAKES THROUGH
MID WEEK. HIGH PRESSURE WILL BUILD IN BY THE END OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
FLURRIES WITH AN OCCASIONAL HEAVIER SNOW SHOWER WILL CONTINUE
ACROSS PORTIONS OF THE AREA THROUGH THE REMAINDER OF THE NIGHT.
THE BETTER CHANCES OF SEEING LIGHT SNOW WILL BE ACROSS THE WESTERN
COUNTY WARNING AREA...INCLUDING THE CENTRAL HIGHLANDS. STILL CANT
COMPLETELY RULE OUT SOME PATCHY FREEZING DRIZZLE BUT BELIEVE
CHANCES ARE TOO LOW TO MENTION.
PREVIOUS DISCUSSION...
THE SNOW WAS ON THE DECREASE AS THE SURFACE LOW OVER WESTERN PA
WAS WEAKENING. GOING WITH LIGHT SNOW OR SNOW SHOWERS TRANSITIONING
TO FLURRIES. LITTLE ADDITIONAL SNOW ACCUMULATION. A LITTLE CONCERN
ABOUT SOME DRIZZLE OR FREEZING DRIZZLE MIXING IN AS SOME DRYING
OCCURS ALOFT. AT THIS TIME IT SEEMS LIKE IT SHOULD BE MAINLY SNOW
OR FLURRIES. ADJUSTED THE LOWS UP A LITTLE BECAUSE OF MOSTLY
CLOUDY SKIES.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
LONGWAVE TROUGH WILL SET UP OVER THE AREA FOR NEXT SEVERAL DAYS
SETTING UP A SITUATION OF ON AGAIN...OFF AGAIN INTERMITTENT SNOW
SHOWERS THROUGH THURSDAY AS SERIES OF SURFACE TROUGHS SWING ACROSS
THE AREA. MODELS INDICATE FIRST TROUGH SHOULD SWING ACROSS THE AREA
TOMORROW AFTERNOON. WENT WITH LIKELY POPS...BUT LOW ACCUMULATIONS.
THE 850 MB TEMPS DIP TO MINUS 10 C TUESDAY SO WILL ALSO HAVE SOME
LAKE ENHANCED SNOW. WITH WINDS SHIFTING FROM NW TO W AND BACK AGAIN
EXPECT MOST OF THE LIGHT SNOW WILL BE CONFINED ACROSS EASTERN HALF
OF THE FORECAST AREA. EXPECT TEMPERATURES TO REMAIN BELOW NORMAL
THROUGH THE PERIOD WITH HIGHS IN THE 30S AND LOWS IN THE 20S.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
THE LONG TERM BEGINS ON FRIDAY WITH MODELS IS GENERAL AGREEMENT
SHOWING A BROAD SURFACE HIGH ACROSS THE OHIO VALLEY AND GREAT LAKES
AND WEAK LOW PRESSURE IN THE SOUTHERN PLAINS. ALOFT...NORTHWEST
FLOW WILL BE ACROSS THE AREA. SATURDAY MODELS CONTINUE TO SHOW HIGH
PRESSURE ACROSS THE OHIO VALLEY HOWEVER BY EVENING THE HIGH WILL
HAVE MOVED EAST. SUNDAY MODELS SHOW THE HIGH WELL OFF THE EAST
COAST WITH AND LOW PRESSURE MOVING THROUGH CENTRAL CANADA. THIS LOW
WILL HAVE A COLD FRONT EXTENDING SOUTH THROUGH THE WESTERN LAKES
THAT WILL DROP ACROSS THE OHIO VALLEY SUNDAY NIGHT. WOULD EXPECT A
DECENT CHANCE OF SHOWERS AHEAD OF THE FRONT ACROSS THE AREA SO WILL
HAVE CHANCE POPS SUNDAY AND SUNDAY EVENING. WILL CONTINUE WITH
CHANCE POPS MONDAY WITH AN UPPER TROF AND ASSOCIATED MOISTURE
DROPPING SOUTH ACROSS THE AREA. TEMPS LOWER THAN NORMAL AT FIRST
BUT TEMPS LOOK TO BE MODERATING TO NEAR NORMAL SATURDAY AND SUNDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
HAVE HAD GOOD IMPROVEMENT FOR AVIATION THE PAST FEW HOURS WITH THE
IFR/MVFR EXITING WITH SOME DRYING COMING IN FROM THE NORTH. SO
QUESTION WILL BE WILL NON-VFR CONDITIONS RE-DEVELOP OVERNIGHT/TOWARD
MORNING. LATEST HRRR GUIDANCE IN PARTICULAR SHOW THE NON VFR
CEILINGS RETURNING TO THE EASTERN HALF OF THE AREA. WITH LAMP GUIDANCE
STILL SUGGESTING SOME IFR...HAVE INCLUDED THAT IN A TEMPO FOR
MFD/CAK. MAY GET SOME MVFR VBSY TO DEVELOP TOO...VERY LOW LEVEL
MOISTURE STICKS AROUND WITH ALL OF THE SNOW ON THE GROUND. OVERALL
A LOW CONFIDENCE FORECAST IN WHAT WILL DEVELOP OVERNIGHT.
FOR TUESDAY ANOTHER TROUGH IN A SERIES WILL MOVE ACROSS NRN OH/NW
PA. THIS WILL BRING AN INCREASE IN SNOW SHOWER ACTIVITY...MOST
NOTABLY FOR THE EASTERN HALF OF THE AREA...BUT TOL/FDY MAY ALSO
SEE SOME LIGHT SNOW. THIS ARRIVES FOR THE AFTERNOON/EARLY EVENING.
.OUTLOOK...NON VFR IN -SHSN CONTINUING INTO THURSDAY.
&&
.MARINE...
THE NORTHEAST WIND WILL BACK TO NORTHWEST AND GRADUALLY DIMINISH
TONIGHT AS LOW PRESSURE MOVES OFF THE EAST COAST. THE SMALL CRAFT
ADVISORY IS TO EXPIRE AT 4 AM AND THAT MAY WORK OUT. THERE WILL BE A
SLIGHTLY LULL IN THE NORTHWEST WIND ON TUESDAY...THEN THE NORTHWEST
WIND MAY PICK BACK UP JUST ENOUGH ON WEDNESDAY INTO THURSDAY AS A
COUPLE OF TROUGHS SWING ACROSS THE EASTERN GREAT LAKES TO REQUIRE
ANOTHER SMALL CRAFT ADVISORY ON THE EAST HALF OF THE LAKE. HIGH
PRESSURE WILL BUILD OVER THE LAKE BY THE WEEKEND.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT EARLY THIS MORNING FOR
LEZ142>149.
&&
$$
SYNOPSIS...DJB
NEAR TERM...KIELTYKA/MULLEN
SHORT TERM...DJB
LONG TERM...TK
AVIATION...OUDEMAN
MARINE...KOSARIK
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
439 AM CDT TUE MAR 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 439 AM CDT TUE MAR 26 2013
PATCHES OF STRATUS DRIFTING SOUTHWARD THROUGH THE CENTRAL PORTIONS
OF THE CWA AT THIS TIME. WILL CARRY SOME OF THIS ALONG I-29 CORRIDOR
INTO THE EARLY MORNING HOURS...BUT EXPECT THAT IT WILL GRADUALLY
DIMINISH AFTER 15Z AS SUGGESTED BY LOW LEVEL RH FIELDS ON LATEST
RAP. THEREAFTER SHOULD SEE FAIR AMOUNT OF SUN TODAY...THOUGH SOME
LINGERING LOW LEVEL MOISTURE COULD LEAD TO SCATTERED AFTERNOON
CU. LIMITED MIXING WITHIN SURFACE RIDGE AXIS WILL KEEP TEMPS QUITE
COOL AGAIN...WITH EXPECTED HIGHS FROM UPPER 20S NORTHEAST TO UPPER
30S FAR SOUTHWEST.
ANY CU SHOULD DIMINISH THIS EVENING...AND EXPECT CENTRAL/EASTERN
PARTS OF THE CWA TO REMAIN CLEAR/PARTLY CLOUDY THROUGH THE NIGHT.
DIFFERENT STORY ACROSS THE WEST HOWEVER...AS BOTH NAM/GFS INDICATE
DEVELOPMENT OF WIDESPREAD STRATUS AND/OR FOG WEST OF THE MISSOURI
RIVER IN UPSLOPE EASTERLY FLOW TOWARD 06Z...THEN EXPANDING INTO OUR
FAR WEST AFTER 09Z. WEAK LIFT IN/JUST ABOVE THE STRATUS LAYER ALSO
INDICATED IN WEAK WARM ADVECTION. UNFORTUNATELY NO SIGN OF MID LEVEL
MOISTURE TO SEED THE STRATUS WITH ICE...AND TEMPS WITHIN THE STRATUS
LAYER TOO WARM FOR ICE INTRODUCTION/INSTA-FLURRIES ON ITS OWN AS WE
SAW WITH THE STRATOCU MONDAY AFTERNOON/EVENING. THUS ANY LIGHT PRECIP
WOULD BE IN FORM OF FREEZING DRIZZLE AND HAVE ADDED THIS ALONG WITH
AREAS OF FOG TO FAR WESTERN AREAS AROUND CHAMBERLAIN LATE TONIGHT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 439 AM CDT TUE MAR 26 2013
ANY STRATUS/FOG/FREEZING DRIZZLE IN THE FAR WEST EXPECTED TO CONTINUE
INTO WEDNESDAY MORNING...POSSIBLY EXPANDING INTO AREAS JUST WEST OF
THE JAMES RIVER/HURON/MITCHELL BEFORE SUBTLE LIFT DIMINISHES AND
WEAK HEATING/MIXING START TO ERODE THE STRATUS. LOW LEVEL MOISTURE
LINGERS HOWEVER...DRIFTING EAST AHEAD OF WEAK INVERTED TROUGH AXIS
WEDNESDAY INTO WEDNESDAY NIGHT. COULD THEN BE LOOKING AT FAIR AMOUNT
OF CLOUDS LATER WEDNESDAY NIGHT THROUGH THURSDAY...WHICH WOULD HOLD
TEMPS DOWN FROM FULL POTENTIAL THURSDAY GIVEN 925MB TEMPERATURES
FINALLY WARMING ABOVE ZERO. STILL EXPECT SLIGHTLY WARMER TEMPERATURES
THURSDAY...WITH HIGHS THURSDAY IN THE UPPER 30S AND 40S. MODELS STILL
TRY TO PRODUCE PATCHY LIGHT QPF THROUGH THIS PERIOD...HOWEVER GIVEN
UNCERTAINTY IN STRATUS PERSISTENCE/EXPANSION...OPTED TO NOT INCLUDE
ANY MENTION OF FOG OR DRIZZLE/FREEZING DRIZZLE AT THIS POINT. WILL BE
SOMETHING FOR FUTURE SHIFTS TO EXAMINE MORE CLOSELY THOUGH.
GREATER WARMUP EXPECTED LATE THIS WEEK...AHEAD OF UPPER WAVE AND
ASSOCIATED COLD FRONT. AS IS TYPICAL IN TRANSITIONAL PATTERNS...
MODELS HAVING TOUGH TIME AGREEING ON TIMING OF BOUNDARIES/ASSOCIATED
DEGREE OF WARMING/COOLING. GENERAL CONSENSUS SHOWS FRIDAY SHOULD BE
OUR FIRST GOOD CHANCE OF SEEING NEAR NORMAL TEMPERATURES...AND WITH
SLIGHTLY BETTER MIXING AHEAD OF INCOMING WAVE...WILL STICK WITH HIGHS
FROM THE UPPER 40S NORTHEAST TO UPPER 50S SOUTHWEST. HIGHS SATURDAY
COULD BE A BIT MORE DEPENDENT ON TIMING OF THE FRONT...WHICH HAS
TRENDED A BIT FASTER THAN WAS SEEN LAST NIGHT. GIVEN UNCERTAINTY IN
TIMING AT THIS RANGE...WILL STAY FAIRLY CLOSE TO MODEL CONSENSUS...
WHICH STILL PUTS MOST AREAS A FEW DEGREES ABOVE LATE MARCH NORMALS.
WITH FASTER TREND IN FRONTAL TIMING FROM 24 HOURS AGO...BETTER PRECIP
CHANCES WILL ADJUST ACCORDINGLY. LOOKING AT A SLIGHT CHANCE ACROSS
THE WEST/NORTH FRIDAY NIGHT...WITH BETTER CHANCE ACROSS THE SOUTHEAST
HALF OF THE CWA SATURDAY. WITH MOIST SOUTHERLY FLOW AHEAD OF BOUNDARY
FRIDAY NIGHT...TEMPERATURES SHOULD REMAIN WARM ENOUGH THAT ANY PRECIP
WOULD REMAIN LIQUID...WITH RAIN SHOWERS CONTINUING INTO SATURDAY AND
SATURDAY EVENING. MORE UNCERTAINTY IN SPEED OF COOLING LATER SATURDAY
NIGHT...BOTH SURFACE AND ALOFT...SO WILL INTRODUCE RAIN/SNOW MIX FOR
PARTS OF NORTHWEST IOWA THEN...ALTHOUGH GOOD CHANCE THAT ANY PRECIP
WOULD BE SOUTHEAST OF THE AREA BEFORE TEMPERATURES COOL ENOUGH FOR
CHANGEOVER.
SUNDAY IS DAY OF GREATEST TEMPERATURE UNCERTAINTY...AS GFS PUSHES
COLD AIR THROUGH MORE QUICKLY...WHILE ECMWF HOLDS ONTO WARMER AIR
UNTIL SECONDARY TROUGH ROTATES AROUND ONTARIO/HUDSON BAY UPPER LOW
SUNDAY NIGHT. THIS LEADING TO 20+ DEGREE DIFFERENCES BETWEEN HIGH
TEMPERATURES FORECAST BY THESE MODELS ON SUNDAY...WITH 26/00Z ECMWF
IN THE 50S-LOWER 60S FOR EASTER SUNDAY...AND CORRESPONDING GFS IN
THE 30S-LOWER 40S. 00Z CANADIAN MORE SUPPORTIVE OF SLOWER COOLING AND
THUS WILL HEDGE TOWARD THE WARMER SIDE OF CONSENSUS AVERAGE...BUT
STILL BACK TO A SHADE BELOW NORMAL...ESPECIALLY ACROSS THE NORTH.
ALTHOUGH ECMWF TIMING FOR COOLDOWN LAGS THE GFS...TEMPERATURES FOR
MONDAY HAVE TRENDED TOWARD THE COLDER SOLUTION AND WILL LIKEWISE
TREND COOLER WITH HIGHS FOR MONDAY. STILL GOING A GOOD 5-10 DEGREES
ABOVE WHAT RAW ECMWF/GFS MODEL GUIDANCE SUGGESTS FOR NOW THOUGH...
ALLOWING FOR A FEW MORE DAYS OF WAVERING ON TIMING BEFORE MODELS
REALLY LOCK ONTO PREFERRED SOLUTION.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1042 PM CDT MON MAR 25 2013
DESPITE NAM GUIDANCE SUGGESTING FAIRLY SUBSTANTIAL FOG THREAT FOR
KHON...HAVE KEPT MENTION OUT OF FORECAST WITH BOTH HRRR AND RAP
CONTINUING TO SUGGEST RADIATIONAL FOG WOULD REMAIN ACROSS
NORTHEAST PORTIONS OF SOUTH DAKOTA. WITH SCATTERED CLOUDS ACROSS
THE AREA...RADIATIONAL COOLING WILL BE RETARDED...THUS LIMITING
FOG POTENTIAL. LIGHT WINDS AND MOSTLY CLEAR SKIES WILL PREVAIL ON
TUESDAY WITH LIGHT EASTERLY FLOW DEVELOPING TUESDAY EVENING.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...JH
LONG TERM...JH
AVIATION...
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
606 AM CDT TUE MAR 26 2013
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
323 AM CDT TUE MAR 26 2013
MAIN FORECAST CONCERNS THIS PACKAGE...CLOUD AND TEMPERATURE TRENDS
THROUGH THE PERIOD.
06Z DATA ANALYSIS HAD AN AREA OF LOW PRESSURE CENTERED OFF THE MID
ATLANTIC COAST WITH ITS BROAD CIRCULATION AS FAR NORTHWEST AS ONT/
MN/IA/WI. A RIDGE OF HIGH PRESSURE EXTENDED FROM MAN TO TX. LOWER
LEVEL MOISTURE WRAPPING AROUND THE BROAD LOW CIRCULATION REMAINED
OVER WI AND EASTERN MN/IA. TEMPERATURES UNDER THE CLOUDS WERE MOSTLY
IN THE MID 20S-LOW 30S WHILE FURTHER WEST CLOSER TO THE SFC RIDGE
AXIS MOST TEMPERATURES WERE IN THE SINGLE DIGITS AND TEENS.
26.00Z MODELS INITIALIZED WELL AND OFFER SIMILAR SOLUTIONS FOR TODAY
THRU THU NIGHT AS HGTS SLOWLY RISE AND THE LOW/MID LEVELS GRADUALLY
WARM. DPROG/DT OF 500MB HGTS AT 26.00Z SHOWED THE MODEL RUNS OF
24.00Z AND 25.00Z VERIFIED QUITE WELL ACROSS NOAM/EASTERN PAC
CONSIDERING ALL THE SMALLER WAVES/RIPPLES IN THE RATHER ACTIVE FLOW
PATTERN. TREND FAVORS A CONSENSUS OF THE EARLIER RUNS WITH MOST OF
THE FEATURES. TIGHTER CONSENSUS FOR TODAY THRU WED NIGHT FOR
LONGWAVE TROUGHING TO REMAIN OVER THE EASTERN CONUS...CONFLUENT
NORTHWEST FLOW TO REMAIN OVER THE UPPER MIDWEST AND WEAK RIDGING TO
BUILD INTO SOUTH-CENTRAL CAN. CONSISTENCY REMAINS AS GOOD AS CAN BE
EXPECTED BY THU/THU NIGHT...ESPECIALLY WITH THE SHORTWAVE DETAILS
IN RATHER BROAD NORTHWEST FLOW FROM SOUTHWEST CAN TO THE SOUTHEAST
U.S. COAST AS THE EASTERN CONUS TROUGH BEGINS TO EXIT OFF THE COAST.
CHECK OF OBS VS. MODEL DATA AT 06Z SHOW ALL TO BE GOOD WITH THE SFC
MASS FIELDS OVER CENTRAL NOAM. DETERMINISTIC MODELS GENERALLY
STRUGGLING WITH THE CLOUDS/MOISTURE NEAR 850MB ACROSS MN/IA/WI...
MOST TEND TO BE TOO FAR WEST WITH THE MOISTURE/CLOUDS OVER MN/IA.
HOWEVER ALL DO GIVE INDICATIONS OF THE HOLES SEEN IN THE CLOUD DECKS
EARLY THIS MORNING. SREF MEAN ACTUALLY LOOKS TO HAVE A DECENT HANDLE
ON THE 850MB MOISTURE/CLOUDS AT 06Z. PER WV IMAGERY...MODELS ALL
APPEAR RESPECTABLE WITH THE SHORTWAVE DETAILS OVER NOAM/EASTERN
PAC. NO ONE MODEL FAVORITE AND WITH A TREND TOWARD A TIGHTER...
COMPROMISE CONSENSUS THRU WED NIGHT...FAVORED A MODEL/ENSEMBLE
BLEND. SHORT TERM FCST CONFIDENCE AVERAGE TO GOOD THIS CYCLE.
IN THE SHORT TERM...MOISTURE AND CLOUDS NEAR 850MB WILL BE
PROBLEMATIC TODAY INTO WED. AXIS OF MOISTURE/CLOUDS FROM NORTH OF
LK SUPERIOR SOUTHWARD ACROSS WI/MI ROTATES SLOWLY SOUTH-SOUTHWEST
ON THE WESTERN EDGE OF THE BROAD EASTERN CONUS CIRCULATION. 850MB
GRADIENT WEAKENS OVER THE AREA TODAY...SO THIS MOISTURE/CLOUDS LOOK
STUCK OVER THE AREA AT LEAST TODAY. INCREASED/HELD MORE CLOUD COVER
OVER THE AREA TODAY...ESPECIALLY ALONG/EAST OF THE MS RIVER. THIS
MOISTURE REMAINS OVER THE AREA TONIGHT...BUT BECOMES SHALLOWER
UNDER A SUBSIDENCE INVERSION AS THE SFC-850MB AXIS IN THE PLAINS
MOVES EAST INTO MN/IA. BY TONIGHT/WED 850MB TEMPS START TO WARM AS
WELL. WITH NO INFLUX OF NEW MOISTURE...WILL REMAIN OPTIMISTIC FOR
CLOUDS TO DECREASE TONIGHT. WINDS LIGHTER TONIGHT AS THE SFC RIDGE
AXIS MOVES INTO MN/IA...FOR A COLDER NIGHT MOST AREAS WITHOUT THE
CLOUD BLANKET.
925-850MB TEMPS SLOWLY WARM WED/THU WITH MORE SUNSHINE/MIXING AS
THE SFC RIDGE AXIS DRIFTS OVER THE AREA AND THE PATTERN SLOWLY
PROGRESSES. MORE SUNSHINE AND GRADUAL AIRMASS MODIFICATION LOOK TO
ADD ABOUT A CATEGORY TO THE HIGHS BOTH WED AND THU.
PRECIP CHANCE REMAIN ABOUT NIL TODAY THRU THU NIGHT WITH A STRONG
CONSENSUS FOR A DRY 825-500MB AIRMASS OVER THE REGION AND THE
SHORTWAVES IN THE NORTHWEST FLOW WEAKENING AS THE DROP INTO THE
CONFLUENT MID LEVEL FLOW OVER THE UPPER MIDWEST.
FAVORING THE MODEL/ENSEMBLE CONSENSUS...USED A BLEND OF THE
NUMERICAL GUIDANCE HIGHS/LOWS FOR TODAY THRU THU NIGHT. WILL HAVE TO
WATCH LOWS TONIGHT IF SKIES CLEAR QUICKLY THIS EVENING AND WINDS
BECOME LIGHT/VARIABLE. LOWS IN SOME OF THE SHELTERED/NORMALLY
COLDER VALLEYS COULD DROP INTO THE SINGLE DIGITS OVER THE
PERSISTENT SNOW COVER.
.LONG TERM...FRIDAY THROUGH MONDAY
323 AM CDT TUE MAR 26 2013
26.00Z MEDIUM RANGE MODELS IN GOOD AGREEMENT FOR DRY/QUIET/WARMING
WEATHER TO CONTINUE FRI. THIS AS HGTS SLOWLY RISE...THE SFC RIDGE
AXIS DRIFTING EAST OF THE AREA AND LOW LEVEL WARM ADVECTION
INCREASING OVER MN/IA/WI. HIGHS FRI LOOKING TO TACK ON ANOTHER
CATEGORY OR TWO OVER THOSE OF THU AS 925MB TEMPS CLIMB ABOVE 0C
ACROSS THE AREA.
CONSISTENCY REMAINS GOOD FOR A STRONGER NORTHWEST FLOW SHORTWAVE
AND TROUGH TO APPROACH SAT...PUSHING A MDT COLD FRONT SOUTHEAST
ACROSS THE UPPER MIDWEST. MOISTURE/LIFT INCREASE AHEAD OF/WITH THIS
FRONT/TROUGH...WITH PW VALUES IN THE 0.5 TO 0.75 INCH RANGE BY SAT
AFTERNOON. MODEST/MOIST ADIABATIC LAPSE RATES INDICATED ABOVE 800MB
AS WELL...FOR MORE EASILY VERTICALLY MOVED PARCELS. COLUMN WARM
ENOUGH FOR ANY PRECIP AS RAIN SAT/SAT EVENING. WITH AREA AHEAD OF
THE FRONT ON SAT AND CONTINUED LOW LEVEL WARM ADVECTION...HIGHS IN
THE UPPER 40S-LOW 50S APPEAR REASONABLE.
CONFIDENCE DROPS FOR SAT NIGHT THRU MON AS MODELS DIFFER ON THE
DETAILS WITH THE CANADIAN AIRMASS INTRUSION BEHIND THE COLD FRONT
STARTING SAT NIGHT. GFS WITH A RAPID INFLUX OF COLDER AIR ALREADY BY
SUN MORNING...ECMWF/UKMET WOULD BRING THE COLDER AIR IN BEHIND A
SECONDARY COLD FRONT SUN NIGHT WHILE GEM A GLANCING BLOW AT BEST.
ECMWF OFFERS THE BETTER RUN-TO-RUN CONSISTENCY WITH ITS 25.00Z AND
25.12Z RUNS FOR THIS TIME PERIOD...WHICH GIVES THE AREA A COOLER DAY
SUNDAY...BUT STILL NEAR NORMAL. WITH THE MIXED TEMP/COLD AIR SIGNALS
BEHIND THE FIRST FRONT...WILL LEAVE PRECIP CHANCES FOR LATE SAT
NIGHT/SUN MORNING AS -RA OR -SN FOR MUCH OF THE AREA. FAVORING
THE MODEL/ENSEMBLE CONSENSUS IN THE DAY 6/7 TIME-FRAME...SMALL -RA
AND/ OR -SN CHANCES SUN-MON IN COLDER CYCLONIC FLOW LOOK REASONABLE
FOR NOW. MODEL/ENSEMBLE CONSENSUS OF THE HIGHS/LOWS FOR FRI-MON LOOK
GOOD AS WELL UNTIL A CLEARER/PREFERRED MODEL SIGNAL IS SEEN.
&&
.AVIATION...TODAY AND TONIGHT
606 AM CDT TUE MAR 26 2013
LARGE AREA OF VFR CLOUDS COVERS MUCH OF WISCONSIN AND THE EASTERN
SECTIONS OF MINNESOTA EARLY THIS MORNING. ONE OF THE LAST PATCHES
OF CLEARING IS OVER KLSE BUT SATELLITE IMAGES SHOW THE CLOUDS
WILL BE PUSHING BACK OVER KLSE AROUND 12Z AND PLAN TO START THEM
WITH A BROKEN VFR CEILING. WITH ALL THE CLOUDS UPSTREAM...EXPECT
THE VFR CEILINGS TO REMAIN IN PLACE UNTIL THE HIGH PRESSURE RIDGE
FROM THE WEST CAN BUILD OVER THE AREA. THE 26.06Z NAM AND 26.09Z
RAP INDICATE THE RIDGE COMING IN LATE THIS AFTERNOON INTO THE
EVENING. THE RAP BUFKIT SOUNDINGS SEEM TO HAVE A BETTER HANDLE ON
THE MOISTURE WITH THE CLOUDS AND SUGGESTS KRST SHOULD SCATTER OUT
LATE THIS AFTERNOON WITH THE CLOUDS BREAKING UP AT KLSE THIS
EVENING. ONCE THE CLOUDS BREAK UP...EXPECTING CLEAR SKIES TO
PREVAIL THROUGH THE OVERNIGHT HOURS WITH THE HIGH CONTINUING TO
BUILD INTO THE REGION.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
323 AM CDT TUE MAR 26 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...04
AREA FORECAST DISCUSSION
NWS LINCOLN IL
251 PM CDT TUE MAR 26 2013
.DISCUSSION...
ISSUED 240 PM CDT TUE MAR 26 2013
SHORT TERM...TONIGHT THROUGH FRIDAY
TEMPERATURES OVER THE SNOW COVERED AREAS OF CENTRAL IL THE MAIN
FORECAST CHALLENGE THE NEXT SEVERAL DAYS.
RATHER QUIET WEATHER PATTERN FOR OUR AREA AS NORTHWEST FLOW DOMINATES
WITH ONLY MINOR UPPER LEVEL SHORTWAVES EXPECTED TO PASS CLOSE TO THE
REGION. SURFACE RIDGE AXIS...CURRENTLY TO OUR WEST...WILL SHIFT OVER
THE MIDWEST ON WEDNESDAY AND EDGE TO OUR EAST BY LATE THURSDAY INTO
FRIDAY. MODELS SUGGEST A BIT MORE SIGNIFICANT WAVE TO DROP SOUTHEAST
ALONG A TIGHT BAROCLINIC ZONE TO OUR SOUTHWEST LATE WED NIGHT INTO
THURSDAY...BRINGING AN INCREASE IN CLOUDS AND THREAT FOR RAIN OVER
PARTS OF MO INTO SOUTHERN IL. AIR MASS IN OUR REGION APPEARS TO BE
TOO DRY TO SUPPORT PRECIP WITH THIS PARTICULAR DISTURBANCE BASED ON
SOUNDINGS OVER OUR SOUTH AND SOUTHWEST...SO WILL KEEP LATE WED AND
THURSDAY DRY.
NEXT UPPER LEVEL SHORTWAVE TRACKING EVEN FURTHER TO OUR SOUTHWEST
ON FRIDAY WITH PRECIP FROM THAT SYSTEM OCCURRING OVER PARTS OF
SOUTHERN MISSOURI AND THE SOUTHERN TIP OF IL DURING THE DAY...WHILE
FURTHER NORTH IN OUR AREA...SURFACE HIGH PRESSURE WILL SLOWLY PUSH
AWAY FROM THE STATE.
TRENDING CLOSER TO THE COOLER TEMP GUID (USUALLY THE MET GUID) FOR
DAYTIME HIGHS...EXCEPT FOR THE SOUTHEAST...AND A MAVMET BLEND AT
NIGHT LOOKS REASONABLE DURING THIS PERIOD.
LONG TERM...SATURDAY THROUGH TUESDAY
FLAT W-NW FLOW PATTERN FORECAST TO UNDERGO SOME SIGNIFICANT CHANGES
EARLY NEXT WEEK AS A SERIES OF SHORTWAVES EXPECTED TO CARVE OUT
ANOTHER STRONG UPPER LEVEL TROF OVER THE GREAT LAKES BRINGING A
SHOT OF COLD AIR BACK INTO OUR AREA.
JUST AHEAD OF THE TROF LATE SATURDAY INTO SUNDAY...RAIN CHANCES
WILL START TO INCREASE AHEAD OF THE APPROACHING COLD FRONT. MILD
TEMPS SHOULD HOLD ON SATURDAY AND A PART OF SUNDAY AHEAD OF THE
FRONT...HOWEVER...ONCE THE FRONT SWEEPS THROUGH THE AREA LATER
SUNDAY INTO SUNDAY NIGHT...MUCH COLDER WEATHER TO SETTLE IN FOR
EARLY NEXT WEEK AS CANADIAN HIGH PRESSURE SHIFTS SOUTHEAST INTO
THE MIDWEST. WITH THE COLD AIR IN PLACE...MODELS INDICATING A
SOUTHERN STREAM WAVE PUSHING ACROSS CALIFORNIA SUNDAY NIGHT WILL
SHIFT EAST INTO THE CENTRAL PLAINS TUESDAY AND BEGIN SPREADING
PRECIP BACK NORTH AND EAST INTO THE COLD AIR MASS. JUST HOW FAR
NORTH AND EAST THE PRECIP GETS IS BEING HANDLED DIFFERENTLY BY
MEDIUM RANGE MODELS WITH THE GFS APPEARING TO BE TOO AGGRESSIVE IN
BRINGING THE PRECIP NORTH INTO A MORE CONFLUENT FLOW ALOFT...
WHILE THE ECMWF WAS MORE CONSERVATIVE IN TIMING AND NORTHWARD
EXTENT TUE/TUESDAY NIGHT. AT THIS POINT...THE ECMWF LOOKS MORE
REASONABLE WITH HOW IT IS HANDLING THE SOUTHERN STREAM SYSTEM
IN THE AMPLIFIED FLOW PATTERN...SO WILL KEEP TUESDAY DRY AT THIS
TIME.
TEMPERATURES START OUT CLOSE TO OR JUST BELOW NORMAL SATURDAY AND
SUNDAY...BEFORE A RETURN TO SOME RATHER CHILLY TEMPERATURES AGAIN
EARLY NEXT WEEK.
SMITH
&&
.AVIATION...
ISSUED 104 PM CDT TUE MAR 26 2013
MAIN TAF CONCERN WILL BE THE RETURN OF CLOUDS TO CENTRAL AND
EASTERN IL THIS AFTERNOON...AND THEN THE TIMING ON THE DISSIPATION
OF CLOUDS TONIGHT.
THE HRRR MODEL HAS DONE A GOOD JOB WITH DEPICTING THE RETURN OF
CLOUDS TO NW AND WEST CENTRAL IL EARLY THIS AFTERNOON. SATELLITE
LOOPS SHOW THAT THE LEADING EDGE OF THESE CLOUDS IS ROTATING DOWN
FROM NORTHERN IL TOWARD THE I-74 CORRIDOR AT 17Z. THE CEILINGS ARE
EXPECTED TO BE ON THE LOWER END OF VFR...AND HAVE DECIDED TO DROP
THEM INTO THE MVFR CATEGORY AT PIA AND BMI BY THIS EVENING. THE
CLOUDS WILL GRADUALLY SPREAD TOWARD THE I-72 CORRIDOR LATER THIS
AFTERNOON.
THE CONCERN THEN SHIFTS TO THE DISSIPATION OF THE CLOUDS. THE NAM
KEEPS CEILINGS GOING FOR THE NEXT 24-36 HOURS...WHILE THE GFS
SCATTERS THE LOWER CLOUDS OUT BEFORE 06Z TONIGHT. THE NAM SEEMS TO
BE HOLDING ON TO THE LOW LEVEL MOISTURE WAY TOO LONG...WHILE THE
GFS MAY BE A BIT QUICK. WITH THE SHORTWAVE ENERGY ROTATING THROUGH
THE GREAT LAKES DURING THE EVENING INTO EARLY TONIGHT WILL KEEP
THE BROKEN CLOUDS GOING UNTIL A FEW HOURS BEFORE DAYBREAK.
THE NEXT SHORTWAVE WILL BE APPROACHING FROM THE NORTHERN PLAINS VERY
CLOSE TO DAYBREAK AND MOVING THROUGH DURING THE MORNING WITH
MAINLY HIGH CLOUDS..BUT INCREASING LOW LEVEL SUBSIDENCE WHICH
SHOULD RESULT IN SCATTERED LOW LEVEL CLOUDS AND NO PRECIPITATION.
MILLER
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
102 PM CDT TUE MAR 26 2013
.DISCUSSION...
ISSUED 1049 AM CDT TUE MAR 26 2013
MADE SOME MINOR ADJUSTMENTS TO THE FORECAST FOR SKY COVER AND
TWEAKED TEMPERATURES A BIT FOR THIS AFTERNOON. THE LATEST VISIBLE
SATELLITE SHOWING A CLEAR SKY ALONG AND WEST OF THE IL RIVER..WITH
PARTLY SUNNY CONDITIONS BETWEEN I-55 AND I-57 AND CLOUDY
CONDITIONS IN THE EAST AND SOUTHEAST. THE MODELS HAVE DONE A POOR
JOB OF FORECASTING THE LOW LEVEL MOISTURE FIELDS AND CLOUDS...WITH
THE EXCEPTION OF THE HRRR WHICH NAILED THE CLEARING TRENDS.
SATELLITE AND THE HRRR BOTH INDICATE THAT CLOUDS WILL ADVECT/FILL
BACK IN ACROSS WEST CENTRAL AND CENTRAL IL THIS AFTERNOON.
&&
.AVIATION...
ISSUED 104 PM CDT TUE MAR 26 2013
MAIN TAF CONCERN WILL BE THE RETURN OF CLOUDS TO CENTRAL AND
EASTERN IL THIS AFTERNOON...AND THEN THE TIMING ON THE DISSIPATION
OF CLOUDS TONIGHT.
THE HRRR MODEL HAS DONE A GOOD JOB WITH DEPICTING THE RETURN OF
CLOUDS TO NW AND WEST CENTRAL IL EARLY THIS AFTERNOON. SATELLITE
LOOPS SHOW THAT THE LEADING EDGE OF THESE CLOUDS IS ROTATING DOWN
FROM NORTHERN IL TOWARD THE I-74 CORRIDOR AT 17Z. THE CEILINGS ARE
EXPECTED TO BE ON THE LOWER END OF VFR...AND HAVE DECIDED TO DROP
THEM INTO THE MVFR CATEGORY AT PIA AND BMI BY THIS EVENING. THE
CLOUDS WILL GRADUALLY SPREAD TOWARD THE I-72 CORRIDOR LATER THIS
AFTERNOON.
THE CONCERN THEN SHIFTS TO THE DISSIPATION OF THE CLOUDS. THE NAM
KEEPS CEILINGS GOING FOR THE NEXT 24-36 HOURS...WHILE THE GFS
SCATTERS THE LOWER CLOUDS OUT BEFORE 06Z TONIGHT. THE NAM SEEMS TO
BE HOLDING ON TO THE LOW LEVEL MOISTURE WAY TOO LONG...WHILE THE
GFS MAY BE A BIT QUICK. WITH THE SHORTWAVE ENERGY ROTATING THROUGH
THE GREAT LAKES DURING THE EVENING INTO EARLY TONIGHT WILL KEEP
THE BROKEN CLOUDS GOING UNTIL A FEW HOURS BEFORE DAYBREAK.
THE NEXT SHORTWAVE WILL BE APPROACHING FROM THE NORTHERN PLAINS VERY
CLOSE TO DAYBREAK AND MOVING THROUGH DURING THE MORNING WITH
MAINLY HIGH CLOUDS..BUT INCREASING LOW LEVEL SUBSIDENCE WHICH
SHOULD RESULT IN SCATTERED LOW LEVEL CLOUDS AND NO PRECIPITATION.
MILLER
&&
.PREV DISCUSSION...
ISSUED 245 AM CDT TUE MAR 26 2013
SHORT TERM...TODAY THROUGH WEDNESDAY
MAIN TROF AXIS HAS SHIFTED SOUTH OF THE CWA WITH LINGERING
FLURRIES EXITING THE SE CWA EARLY THIS MORNING. PLENTY OF STRATOCU
OVERHEAD AND UPSTREAM AND WITH CYCLONIC LOW LEVEL FLOW CONTINUING
TODAY MOSTLY CLOUDY SKIES EXPECTED. SOME CLEARING NOTED ON IR SAT
IMAGERY OVER NRN IA/SRN MN SO SOME BREAKS FOR SUN CERTAINLY
POSSIBLE. LITTLE AIRMASS CHANGE FROM YESTERDAY AND HAVE HIGHS IN
THE MID/UPPER 30S. AN ELONGATED HIGH PRESSURE RIDGE WILL SHIFT EAST INTO
THE MISSISSIPPI VALLEY TONIGHT. IF SUBSIDENCE IS STRONG
ENOUGH TO PROVIDE SOME CLEARING LOW 20S OR EVEN SOME UPPER TEENS
LOWS POSSIBLE WITH SNOW COVER IN PLACE...HOWEVER FEEL CLOUDS MAY
HANG TOUGH WITH BETTER SUBSIDENCE TO OUR WEST SO WENT MORE
CONSERVATIVE LOW/MID 20S LOWS. BOTH NAM/GFS FORECAST SOUNDINGS
STILL SHOW MOISTURE TRAPPED BELOW A STRONG SUBSIDENCE INVERSION
UNDER THE IN-BUILDING RIDGE ON WEDNESDAY. SO WILL BE PESSIMISTIC
WITH CLEARING TRENDS THOUGH STRONGER LATE MARCH SUN COULD BREAK UP
THE CLOUDS FOR MORE OF A PARTLY SUNNY AFTERNOON. A GRADUAL WARMING
TREND WILL BEGIN AND MOST AREAS SHOULD SEE HIGHS IN THE LOWER 40S.
LONG TERM...THURSDAY THROUGH MONDAY
THE SURFACE RIDGE WILL BE THE DOMINANT FEATURE THROUGH THE END OF
THE WEEK AS IT GRADUALLY SHIFTS EAST INTO THE GREAT LAKES. SLOWLY
RISING HEIGHTS ALONG WITH SNOW MELT/MORE BARE GROUND WILL ALLOW
READINGS TO CLIMB A FEW DEGREES BOTH THU AND FRI. A DEVELOPING MID
LEVEL BAROCLINIC ZONE AND SFC WARM FRONT OVER THE MISSOURI
VALLEY...SHOULD KEEP ANY RAIN AND MOST OF THE CLOUD COVER WELL TO
OUR SOUTHWEST. BY SATURDAY THE HIGH SHIFTS EAST INTO THE
APPALACHIANS ALLOWING SOUTHERLY LLVL FLOW TO BRING EVEN WARMER AIR
INTO THE AREA WITH HIGHS EXPECTED INTO THE 50S. AN UPPER LEVEL
TROF MOVING INTO THE NORTHERN PLAINS WILL HELP DRIVE A COLD FRONT
INTO THE MIDWEST SATURDAY. 00Z GUIDANCE HAS SPED UP THE TIMING OF
THIS SYSTEM BY A SEVERAL HOURS...BUT MOST RAIN SHOULD BE ALONG AND
BEHIND THE FRONT. THUS HIGHEST RAIN CHANCES WILL BE SATURDAY NIGHT
AND SUNDAY MORNING. WITH LIMITED GULF MOISTURE ENTRAINED INTO THE
SYSTEM LIGHT AMOUNTS ARE EXPECTED. THE EXTENT OF THE COOL DOWN
BEHIND THIS FRONT IS IN QUESTION AS THE LONGER RANGE MODELS DIFFER
IN HOW FAR SOUTH THE SOUTHERN EXTENSION OF THE POLAR VORTEX DIGS
TOWARDS THE GREAT LAKES. MORE AGGRESSIVE GFS FAVORS A RETURN TO
WELL BELOW NORMAL TEMPS...WHILE THE ECMWF PUSHES THE BRUNT OF THE
COLD AIR OFF TO OUR NORTHEAST. FOR NOW WILL KEEP A BLENDED
FORECAST WITH TEMPS A FEW DEGREES BELOW NORMAL FOR THE BEGINNING
OF NEXT WEEK.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
410 PM EDT TUE MAR 26 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 324 PM EDT TUE MAR 26 2013
SCATTERED FLURRIES AND ISOLATED SNOW SHOWERS SHOULD GIVE
WAY TO DRY CONDITIONS LATER TONIGHT AS AN UPPER RIDGE OF HIGH
PRESSURE MOVES INTO CENTRAL INDIANA. CLOUDS MAY LINGER A BIT LONGER
INTO WEDNESDAY MORNING BUT THEN SHOULD SEE SLOWLY INCREASING
TEMPERATURES AND DECREASING SKY COVER THROUGH THE REMAINDER OF THE
WORK WEEK. SATURDAY NIGHT CHANCES FOR RAIN ARRIVE AS LOW PRESSURE
MOVES THROUGH THE AREA BY SUNDAY NIGHT. TEMPERATURES MAX OUT IN THE
MIDDLE 50S ON SUNDAY BUT THEN DROP AGAIN FOR NEXT WEEK.
&&
.NEAR TERM /THIS EVENING AND TONIGHT/...
ISSUED AT 324 PM EDT TUE MAR 26 2013
RADAR SHOWS SCATTERED WEAK ECHOES ACROSS CENTRAL INDIANA. MOST OF
THESE ARE PRODUCING ONLY FLURRIES...BUT THERE IS A WEAK WAVE MOVING
THROUGH AND SATELLITE IS SHOWING CONVECTIVE ENHANCEMENT TO THE
CLOUDS. WITH THIS IN MIND WILL GO WITH A 20 POP FOR THE REMAINDER OF
THE AFTERNOON FOR MUCH OF THE AREA AND MENTION ISOLATED SNOW SHOWERS
WITH SCATTERED FLURRIES. FOR TONIGHT HELD ONTO SLIGHT CHANCE POPS IN
THE NORTHEAST WITH FLURRIES ELSEWHERE THROUGH 6Z TO COVER LIGHT
ECHOES SHOWING UP IN HRRR DUE TO THE AFOREMENTIONED WEAK WAVE. AFTER
6Z WEATHER SHOULD BE DRY AS HIGH PRESSURE AND UPPER RIDGING START TO
BUILD IN.
INCREASED SKY COVER FROM CONSENSUS TO ACCOUNT FOR THE CYCLONIC
FLOW...LEAVING MOSTLY CLOUDY SKIES IN PLACE FOR MOST OF THE NIGHT.
THIS SHOULD KEEP TEMPERATURES FROM BOTTOMING OUT AND THUS A GUIDANCE
BLEND FOR LOW TEMPERATURES IN THE MIDDLE 20S LOOKED GOOD.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
ISSUED AT 324 PM EDT TUE MAR 26 2013
THE SHORT TERM LOOKS LIKE QUIET WEATHER IS IN STORE AS HIGH PRESSURE
BUILDS OVER THE AREA AND TEMPERATURES SLOWLY BEGIN TO WARM. SHOULD
SEE SKY COVER CLEARING DURING THE DAY ON WEDNESDAY AND LEAVE MOSTLY
CLEAR SKIES IN PLACE FOR WEDNESDAY NIGHT. WHILE THE MAV REBOUNDS
TEMPERATURES QUICKLY THINK THIS WILL BE TEMPERED BY SNOW COVER AND
THUS WENT NEAR RAW MODEL NUMBERS OF THE COOLER NAM. WENT WITH COOLER
CONSENSUS NUMBERS WHICH WERE COOLER THAN EITHER GUIDANCE FOR
WEDNESDAY NIGHT WITH THE MOSTLY CLEAR SKY COVER AND STILL SOME SNOW
PACK ESPECIALLY IN THE NORTH. AS FAR AS WARMING IS CONCERNED...BY
FRIDAY SHOULD SEE HIGHS IN THE UPPER 40S TO LOWER 50S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 245 PM EDT TUE MAR 26 2013
NICE WARMUP IN TEMPS FROM RECENT LEVELS CULMINATES OVER THE
WEEKEND AS MUCH OF THE FORECAST AREA LIKELY TO WARM IN THE 50S.
SATURDAY IN PARTICULAR WILL BE A NICE DAY WITH DRY CONDITIONS AS
HIGH PRESSURE SHIFTS OFF TO THE EAST. MODEL CONSENSUS REMAINS
CONSISTENT WITH TRACKING A COLD FRONT THROUGH THE REGION FOR THE
SECOND HALF OF THE WEEKEND...WITH RAIN LIKELY FROM LATE SATURDAY
THROUGH SUNDAY. IN THE WAKE OF THE FRONT TEMPERATURES WILL ONCE
AGAIN TURN COLDER TO BEGIN THE MONTH OF APRIL AS MODEL GUIDANCE
INDICATING THE POLAR VORTEX DIVING SOUTH INTO THE GREAT LAKES ONCE
AGAIN. THIS WILL ONCE AGAIN REESTABLISH A NORTHWEST FLOW ALOFT AS
THE POLAR VORTEX MOVES INTO NEW ENGLAND BY THE END OF THE PERIOD.
UNDERCUT ALLBLEND TEMPS FOR MONDAY AND TUESDAY AS THE SHOT OF
COLDER AIR IN THE WAKE OF THE PASSAGE OF THE FRONT LIKELY KEEPS
HIGHS IN THE 40S BOTH DAYS.
&&
.AVIATION /DISCUSSION FOR THE 26/21Z TAF UPDATE/...
ISSUED AT 410 PM EDT TUE MAR 26 2013
NO SIGNIFICANT CHANGES NECESSARY. PREVIOUS DISCUSSION FOLLOWS.
ISSUED AT 100 PM EDT TUE MAR 26 2013
BRIEF PERIODS OF MVFR CONDITIONS POSSIBLE THIS AFTERNOON WITHIN
LIGHT SNOW SHOWERS...OTHERWISE VFR EXPECTED THROUGH THE PERIOD.
WEAK RIDGING ALOFT PASSING THROUGH THE OHIO VALLEY EARLY THIS
AFTERNOON...ALLOWING FOR SOME BREAKS IN THE CLOUDS TO DEVELOP.
HAVE SEEN A GRADUAL INCREASE IN COVERAGE TO FLURRIES AND EVEN A
FEW SNOW SHOWERS OVER NORTHERN INDIANA...INFLUENCED BY NORTHWEST
FLOW IN THE LOW LEVELS COMING OFF OF LAKE MICHIGAN...AND THE
APPROACH OF ANOTHER WAVE ALOFT. BOTH OF THESE FEATURES COMBINED
WITH A PERIOD OF STEEPENING LAPSE RATES AND SUBTLE INSTABILITY IS
LIKELY TO CONTRIBUTE SCATTERED FLURRIES/SNOW SHOWERS THROUGH THE
AFTERNOON. WITH UNCERTAINTY TO COVERAGE AT THIS POINT...WILL JUST
CARRY A VCSH MENTION INTO THE EARLY EVENING AT ALL BUT KHUF.
NORTHWEST WINDS AT 10-15KTS WILL CONTINUE.
THE UPPER WAVE WILL MOVE TO THE SOUTHEAST OF THE TERMINALS THIS
EVENING WITH ANY LINGERING FLURRIES ENDING. WHILE IT DOES APPEAR
CLOUDS WILL SCATTER SOMEWHAT LATE TONIGHT AS HIGH PRESSURE NOSES
IN...REGION REMAINS IN A LARGELY CYCLONIC FLOW ALOFT AND WILL KEEP
CLOUDS AROUND INTO WEDNESDAY. W/NW WINDS WILL LIGHTEN UNDER 10KTS
OVERNIGHT AND SHOULD STAY THAT WAY INTO WEDNESDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...CP
NEAR TERM...CP
SHORT TERM...CP
LONG TERM....RYAN
AVIATION...RYAN/NIELD
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
326 PM EDT TUE MAR 26 2013
.UPDATE...
THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 324 PM EDT TUE MAR 26 2013
SCATTERED FLURRIES AND ISOLATED SNOW SHOWERS SHOULD GIVE
WAY TO DRY CONDITIONS LATER TONIGHT AS AN UPPER RIDGE OF HIGH
PRESSURE MOVES INTO CENTRAL INDIANA. CLOUDS MAY LINGER A BIT LONGER
INTO WEDNESDAY MORNING BUT THEN SHOULD SEE SLOWLY INCREASING
TEMPERATURES AND DECREASING SKY COVER THROUGH THE REMAINDER OF THE
WORK WEEK. SATURDAY NIGHT CHANCES FOR RAIN ARRIVE AS LOW PRESSURE
MOVES THROUGH THE AREA BY SUNDAY NIGHT. TEMPERATURES MAX OUT IN THE
MIDDLE 50S ON SUNDAY BUT THEN DROP AGAIN FOR NEXT WEEK.
&&
.NEAR TERM /THIS EVENING AND TONIGHT/...
ISSUED AT 324 PM EDT TUE MAR 26 2013
RADAR SHOWS SCATTERED WEAK ECHOES ACROSS CENTRAL INDIANA. MOST OF
THESE ARE PRODUCING ONLY FLURRIES...BUT THERE IS A WEAK WAVE MOVING
THROUGH AND SATELLITE IS SHOWING CONVECTIVE ENHANCEMENT TO THE
CLOUDS. WITH THIS IN MIND WILL GO WITH A 20 POP FOR THE REMAINDER OF
THE AFTERNOON FOR MUCH OF THE AREA AND MENTION ISOLATED SNOW SHOWERS
WITH SCATTERED FLURRIES. FOR TONIGHT HELD ONTO SLIGHT CHANCE POPS IN
THE NORTHEAST WITH FLURRIES ELSEWHERE THROUGH 6Z TO COVER LIGHT
ECHOES SHOWING UP IN HRRR DUE TO THE AFOREMENTIONED WEAK WAVE. AFTER
6Z WEATHER SHOULD BE DRY AS HIGH PRESSURE AND UPPER RIDGING START TO
BUILD IN.
INCREASED SKY COVER FROM CONSENSUS TO ACCOUNT FOR THE CYCLONIC
FLOW...LEAVING MOSTLY CLOUDY SKIES IN PLACE FOR MOST OF THE NIGHT.
THIS SHOULD KEEP TEMPERATURES FROM BOTTOMING OUT AND THUS A GUIDANCE
BLEND FOR LOW TEMPERATURES IN THE MIDDLE 20S LOOKED GOOD.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
ISSUED AT 324 PM EDT TUE MAR 26 2013
THE SHORT TERM LOOKS LIKE QUIET WEATHER IS IN STORE AS HIGH PRESSURE
BUILDS OVER THE AREA AND TEMPERATURES SLOWLY BEGIN TO WARM. SHOULD
SEE SKY COVER CLEARING DURING THE DAY ON WEDNESDAY AND LEAVE MOSTLY
CLEAR SKIES IN PLACE FOR WEDNESDAY NIGHT. WHILE THE MAV REBOUNDS
TEMPERATURES QUICKLY THINK THIS WILL BE TEMPERED BY SNOW COVER AND
THUS WENT NEAR RAW MODEL NUMBERS OF THE COOLER NAM. WENT WITH COOLER
CONSENSUS NUMBERS WHICH WERE COOLER THAN EITHER GUIDANCE FOR
WEDNESDAY NIGHT WITH THE MOSTLY CLEAR SKY COVER AND STILL SOME SNOW
PACK ESPECIALLY IN THE NORTH. AS FAR AS WARMING IS CONCERNED...BY
FRIDAY SHOULD SEE HIGHS IN THE UPPER 40S TO LOWER 50S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 245 PM EDT TUE MAR 26 2013
NICE WARMUP IN TEMPS FROM RECENT LEVELS CULMINATES OVER THE
WEEKEND AS MUCH OF THE FORECAST AREA LIKELY TO WARM IN THE 50S.
SATURDAY IN PARTICULAR WILL BE A NICE DAY WITH DRY CONDITIONS AS
HIGH PRESSURE SHIFTS OFF TO THE EAST. MODEL CONSENSUS REMAINS
CONSISTENT WITH TRACKING A COLD FRONT THROUGH THE REGION FOR THE
SECOND HALF OF THE WEEKEND...WITH RAIN LIKELY FROM LATE SATURDAY
THROUGH SUNDAY. IN THE WAKE OF THE FRONT TEMPERATURES WILL ONCE
AGAIN TURN COLDER TO BEGIN THE MONTH OF APRIL AS MODEL GUIDANCE
INDICATING THE POLAR VORTEX DIVING SOUTH INTO THE GREAT LAKES ONCE
AGAIN. THIS WILL ONCE AGAIN REESTABLISH A NORTHWEST FLOW ALOFT AS
THE POLAR VORTEX MOVES INTO NEW ENGLAND BY THE END OF THE PERIOD.
UNDERCUT ALLBLEND TEMPS FOR MONDAY AND TUESDAY AS THE SHOT OF
COLDER AIR IN THE WAKE OF THE PASSAGE OF THE FRONT LIKELY KEEPS
HIGHS IN THE 40S BOTH DAYS.
&&
.AVIATION /DISCUSSION FOR 261800Z TAF ISSUANCE/...
ISSUED AT 100 PM EDT TUE MAR 26 2013
BRIEF PERIODS OF MVFR CONDITIONS POSSIBLE THIS AFTERNOON WITHIN
LIGHT SNOW SHOWERS...OTHERWISE VFR EXPECTED THROUGH THE PERIOD.
WEAK RIDGING ALOFT PASSING THROUGH THE OHIO VALLEY EARLY THIS
AFTERNOON...ALLOWING FOR SOME BREAKS IN THE CLOUDS TO DEVELOP.
HAVE SEEN A GRADUAL INCREASE IN COVERAGE TO FLURRIES AND EVEN A
FEW SNOW SHOWERS OVER NORTHERN INDIANA...INFLUENCED BY NORTHWEST
FLOW IN THE LOW LEVELS COMING OFF OF LAKE MICHIGAN...AND THE
APPROACH OF ANOTHER WAVE ALOFT. BOTH OF THESE FEATURES COMBINED
WITH A PERIOD OF STEEPENING LAPSE RATES AND SUBTLE INSTABILITY IS
LIKELY TO CONTRIBUTE SCATTERED FLURRIES/SNOW SHOWERS THROUGH THE
AFTERNOON. WITH UNCERTAINTY TO COVERAGE AT THIS POINT...WILL JUST
CARRY A VCSH MENTION INTO THE EARLY EVENING AT ALL BUT KHUF.
NORTHWEST WINDS AT 10-15KTS WILL CONTINUE.
THE UPPER WAVE WILL MOVE TO THE SOUTHEAST OF THE TERMINALS THIS
EVENING WITH ANY LINGERING FLURRIES ENDING. WHILE IT DOES APPEAR
CLOUDS WILL SCATTER SOMEWHAT LATE TONIGHT AS HIGH PRESSURE NOSES
IN...REGION REMAINS IN A LARGELY CYCLONIC FLOW ALOFT AND WILL KEEP
CLOUDS AROUND INTO WEDNESDAY. W/NW WINDS WILL LIGHTEN UNDER 10KTS
OVERNIGHT AND SHOULD STAY THAT WAY INTO WEDNESDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CP
NEAR TERM...CP
SHORT TERM...CP
LONG TERM....RYAN
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1154 AM MDT TUE MAR 26 2013
.UPDATE...
ISSUED AT 1143 AM MDT TUE MAR 26 2013
COMPLETED AN UPDATE EARLIER. SWITCH IN WIND DIRECTION FROM
YESTERDAY HAS MADE A BIG DIFFERENCE. WITH THE SOUTH WINDS THE
SOUTHEAST FRINGE OF THE AREA THAT HAS LITTLE TO NO SNOW IS WARMING
UP QUICKLY. THE MESOSCALE MODELS ARE CATCHING THIS. HOWEVER...THEY...WITH
THE EXCEPTION OF THE NAM12...ARE EXTENDING THIS WARMING WELL INTO
THE DEEPER SNOWFIELD. NAM IS KEEPING THE MAIN WARMING CONFINED TO
OUR EXTREME SOUTH WHICH IS NOT FAR ENOUGH NORTH IN COMPARISON TO
THE CURRENT OBSERVATIONS.
CONSIDERING THE POSITION AND DEEPENING NATURE OF THE SURFACE LOW
OVER SOUTHEAST COLORADO...BELIEVE AT THIS TIME THAT THE FURTHER
NORTH SOLUTIONS ARE TOO FAR NORTH. SO WILL USE THE MESOSCALE
MODELS TO WARM THIS SOUTHEAST FRINGE AND TEMPER THE WARMING
FURTHER NORTH. VERY LOW CONFIDENCE IN HOW THIS IS GOING TO WORK
OUT. THE HRRR AND NAM ARE CATCHING THE WIND FIELD THE BEST AND
ADJUSTED ACCORDING TO THEM.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY NIGHT)
ISSUED AT 231 AM MDT TUE MAR 26 2013
MAIN FORECAST CONCERN IN THE SHORT TERM PERIOD IS ON TEMPERATURES.
TEMPERATURES WILL WARM THROUGH THE WEEK WITH WEAK RIDGING ALOFT
OVER THE ROCKY MOUNTAIN AND INTERMOUNTAIN WEST AND GENERALLY SOUTH
WINDS AT THE SURFACE OVER THE CENTRAL HIGH PLAINS REGION.
THE COLD HIGH PRESSURE AREA IN PLACE OVER THE REGION WILL MOVE TO
THE EAST TODAY. WINDS BECOME MORE SOUTHERLY AHEAD OF A WEAK
SURFACE TROUGH THAT DEVELOPS ALONG THE FRONT RANGE FROM WYOMING TO
NEW MEXICO IN RESPONSE TO A COUPLE OF SHORT WAVE TROUGHS MOVING
THROUGH APEX OF THE UPPER RIDGE AND EAST OF THE ROCKIES TONIGHT
AND ACROSS THE FORECAST AREA BY MID DAY ON WEDNESDAY. CLOUDS WILL
INCREASE WITH FLURRIES POSSIBLE OVERNIGHT AS THE TROUGH MOVES
ACROSS THE FORECAST AREA.
THE RIDGE REAMPLIFIES WEDNESDAY NIGHT THROUGH THURSDAY NIGHT WITH
DRY CONDITIONS AND TEMPERATURES THAT WILL CONTINUE TO WARM.
SNOWCOVER IS EXPECTED TO SUPPRESS DAYTIME WARMING AND HAVE KEPT
MAINLY THE NORTHWEST PORTION OF THE FORECAST AREA COOLER DURING
THE DAY.
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 102 AM MDT TUE MAR 26 2013
MODELS SHOW A RATHER UNSETTLED LONG TERM PERIOD. THE CENTRAL
PLAINS WILL BE UNDER NORTHWEST FLOW ALOFT TO START THE
PERIOD...FOLLOWED BY BRIEF SHORTWAVE RIDGING AROUND SUNDAY AHEAD
OF A SOUTHERN STREAM DISTURBANCE WHICH WILL APPROACH EARLY NEXT
WEEK. WHILE UNDER NORTHWEST FLOW...A SERIES OF WEAK SHORTWAVE
TROUGHS WILL PROVIDE WEAK FORCING FOR SLIGHT/LOW CHANCES OF
SHOWERS AND PERHAPS AN ISOLATED THUNDERSTORM WITH WEAK SURFACE
BASED INSTABILITY FORECAST FRIDAY AND SATURDAY AFTERNOON/EVENINGS.
DRY WEATHER WILL ACCOMPANY THE RIDGE ON SUNDAY. HOWEVER...BEST
CHANCES FOR PRECIPITATION WILL BE WITH THE SYSTEM EARLY NEXT
WEEK. PRECIPITATION TYPE MAY BE PROBLEMATIC AS MODELS SHOW A
SHALLOW COLD AIR MASS ARRIVING ON MONDAY...WITH FREEZING/FROZEN
PRECIPITATION POSSIBLE. TEMPERATURES MAY BE MUCH COLDER THAN
CURRENTLY FORECAST IN THE MONDAY AND TUESDAY PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1143 AM MDT TUE MAR 26 2013
COMPLICATED SET OF TAFS. WINDS BEING AFFECTED BY THE SNOWFIELD.
IN ADVANCE OF A FAST MOVING SYSTEM...WINDS WILL SHIFT FROM SOUTH
TO NORTH DURING THE NIGHT. MOISTURE AHEAD OF THIS SYSTEM APPEARS
TO BE LACKING. HOWEVER...MODELS SHOWING A RATHER STRONG RIGHT REAR
QUADRANT OF THE JET AND STRONG PV ANOMALY...MAINLY TOWARD THE
SOUTH. SO AT THIS TIME...PUT IN FLURRIES AT KGLD WITHOUT ANY
RESTRICTIONS AND VFR CEILINGS. WITH A LIGHT EASTERLY WINDS
FIELD...THERE WILL BE THE POSSIBILITY OF FOG AT KMCK. CONDITIONS
IMPROVE BY 15Z.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...BULLER
SHORT TERM...LOCKHART
LONG TERM...024
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
112 PM EDT TUE MAR 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 513 AM EDT TUE MAR 26 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A PERSISTENT BLOCKING RIDGE
FROM NRN CANADA INTO HUDSON BAY AND A TROUGH FROM THE CANADIAN
MARITIMES INTO NRN NEW ENGLAND RESULTING IN WEAK NE FLOW THROUGH THE
NRN GRREAT LAKES. AT THE SFC...NRLY FLOW PREVAILED ACROSS LAKE
SUPERIOR BETWEEN A TROUGH INTO THE ERN LAKES AND A RIDGE OVER THE
PLAINS. IR LOOP SHOWED THE BACK EDGE OF THE CLOUDS AND DEEPER
MOISTURE ADVANCING WESTWARD TOWARD THE E SIDE OF LAKE SUPERIOR.
RADAR INDICATED SCT SHSN INTO CNTRL UPPER MI WITH MORE CELLULAR THAN
BANDED PATTERN MORE TYPICAL OF LES. EVEN THOUGH 850 MB TEMPS TO NEAR
-10C ONLY PROVIDED MARGINAL OVER LAKE INSTABILITY...A WEAK SHORTWAVE
TROUGH AND ASSOCIATED 700-300 MB QVECTOR CONV HAS SUPPORTED SHSN
DEVELOPMENT. SNOW/WATER RATIO HAS INCREASED AND -FZDZ POTENTIAL
DIMINISHED WITH MOISTURE THROUGH THE DGZ.
TODAY...AS THE FORCING WITH THE SHRTWV SLIDES OFF TO THE SOUTHEAST
AND THE DEEPER MOISTURE DEPARTS...EXPECT THE SHSN TO QUICKLY
DIMINISH BY LATE MORNING. SO...ADDITIONAL SNOWFALL AMOUNTS OF ONLY A
HALF INCH OR LESS ARE EXPECTED. THERE MAY STILL BE A PERIOD WHERE
SOME -FZDZ IS POSSIBLE AS THE MOIST LAYER FALLS AT OR BELOW THE -10C
LEVEL. WITH DAYTIME HEATING AND GREATER MIXING...THERE MAY EVEN BE A
PERIOD OF SOME CLEARING INTO THE E HALF OF UPPER MI.
OTHERWISE...HIGH TEMPS WILL REMAIN BELOW NORMAL...IN THE LOWER TO
MID 30S.
TONIGHT...ANOTHER BATCH OF 925-850 MB MOISTURE IS EXPECTED TO MOVE
IN FROM THE NORTHEAST BRINGING THE POTENTIAL FOR ANOTHER ROUND OF
LAKE ENHANCED PCPN. SINCE TEMPS NEAR TO THE TOP OF THE MOIST LAYER
AT 850 MB ARE A BIT HIGHER...ONLY TO AROUND -8C...THERE MAY BE A
BETTER CHANCE FOR -FZDZ WITH ANY PCPN THAT DEVELOPS. WITH ONLY A
MODEST NRLY UPSLOPE WIND COMPONENT IN THE 20 TO 25 KNOT RANGE...ONLY
SLIGHT OR LOWER END CHANCE POPS WERE MENTIONED.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 410 AM EDT TUE MAR 26 2013
LINGERING LOW LEVEL MOISTURE ROTATING IN FROM THE NORTH WILL BE
SLOWLY DIMINISHING WITH MUCH OF THE REMAINING FREEZING DRIZZLE AND
LIGHT SNOW SHOWERS/FLURRIES ENDING FOR THE MOST PART ON WEDNESDAY.
MOISTURE WILL BE TRAPPED BELOW 800MB WEDNESDAY MORNING AND FALL
AROUND OR BELOW 900MB BY WEDNESDAY EVENING...UNDER THE STRENGTHENING
INVERSION. WHILE THE MODELS DO SPIT OUT AROUND 0.01IN OR LESS
WEDNESDAY NIGHT AND THURSDAY...SIGNIFICANT PRECIP IS NOT ANTICIPATED.
THE STEADILY WARMING AFTERNOON HIGH TEMPERATURES WILL CONTINUE AS
THE 500MB HIGH OVER HUDSON BAY ON TUESDAY SINKS INTO ONTARIO AND
COMBINES WITH THE RIDGE ALREADY SET UP ACROSS THE WESTERN HALF OF
THE UNITED STATES. 850MB TEMPS AROUND -11C WEDNESDAY MORNING WILL
WARM TO -6C BY 12Z THURSDAY ON CONTINUED NORTHERLY WINDS...AND
REMAIN NEARLY STEADY THROUGH FRIDAY AFTERNOON.
A WEAK SHORTWAVE WILL SWING IN ON THE NORTHWESTERLY FLOW ALOFT
THURSDAY NIGHT INTO EARLY FRIDAY...WITH LITTLE INFLUENCE ON OUR
WEATHER. THE WRAPPED UP 500MB LOW ENCOMPASSING MUCH OF CENTRAL
CANADA FROM MID WEEK ON WILL DIG A TROUGH ACROSS THE NORTHERN PLAINS
FRIDAY NIGHT INTO SATURDAY...AND EXTEND TO THE UPPER GREAT LAKES
FROM SATURDAY THROUGH AT LEAST MONDAY. TIMING AND STRENGTH OF THE
ASSOCIATED COLD FRONT IS STILL IN QUESTION...BUT IT LOOKS LIKE IT
SHOULD BE OVER FAR WESTERN LAKE SUPERIOR SATURDAY AFTERNOON...AND
SLOWLY TRANSITION ACROSS CENTRAL AND EASTERN LAKE SUPERIOR SATURDAY
NIGHT...AS THE SFC LOW DRIFTS OVER CENTRAL ONTARIO.
WHILE THE GFS IS MORE PROGRESSIVE WITH THE FRONT...AND BUILDS COLD
HIGH PRESSURE BACK INTO WESTERN AND CENTRAL LAKE SUPERIOR ON
SUNDAY...THE ECMWF HOLDS ONTO THE SFC TROUGH A BIT LONGER. THE
DIFFERENCE SHOWS UP WELL ON THE 850MB CHART...WITH TEMPS OF -14C AT
18Z SUNDAY OFF THE GFS...WHILE THE ECMWF STILL HAS READINGS AROUND
-4C...AND KEEPS ANY COOLER READINGS BELOW -10C TO LATE SUNDAY NIGHT
AND BEYOND. THE 500MB TROUGH SHOULD PUSH EAST INTO THE LOWER GREAT
LAKES AND EASTERN ONTARIO ON MONDAY...WITH NORTHWESTERLY FLOW
REMAINING ALOFT THROUGH AT LEAST TUESDAY. ON A SIDE NOTE...THE
00Z/26 RUN OF THE ECMWF SIGNIFICANTLY INTENSIFIED THE SOUTHERN EDGE
OF THE TROUGH ROTTING THROUGH THE AREA SUNDAY NIGHT. THIS WOULD
RESULT IN A BETTER CHANCE OF PRECIPITATION...AND MUCH STRONGER
WINDS. AT 12Z MONDAY THE 12Z/25 RUN HAD WINDS OF UP TO 25KTS AT
850MB. THE LATEST RUN...WITH A SECONDARY DEEPENING SFC LOW CROSSING
CENTRAL AND EASTERN UPPER MICHIGAN SUNDAY NIGHT ALLOWS FOR A 45-60KT
850MB LLJ TO CROSS AT 12Z MONDAY. WILL BE INTERESTING IF THE 12Z RUN
LATER TODAY KEEPS UP THIS TREND...BUT FOR NOW WILL KEEP IT OUT OF
THE ONGOING FORECAST...WITH NO GALES OVER THE LAKE EXPECTED QUITE
YET.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 111 PM EDT TUE MAR 26 2013
VFR CONDITIONS WILL CONTINUE PREVAIL AT ALL SITES THIS AFTERNOON.
UNTIL THE DRIER AIR GETS IN AT SAW...MVFR CIGS WILL BE IN EARLY THIS
AFTERNOON. WITH THE LOSS OF DAYTIME HEATING/MIXING AND WITH
ADDITIONAL LOW LEVEL MOISTURE MOVING IN FROM THE NORTHEAST AND WEAK
UPSLOPE FLOW...MVFR CIGS ARE EXPECTED AGAIN TONIGHT INTO WED
MORNING. THERE COULD ALSO BE SOME UPSLOPE FLURRIES AND FREEZING
DRIZZLE AT IWD AND SAW OVERNIGHT TONIGHT INTO WED MORNING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 513 AM EDT TUE MAR 26 2013
HIGH PRESSURE OVER THE PLAINS WILL ONLY SLOWLY BUILD TO THE EAST
TODAY INTO WEDNESDAY KEEPING NORTHERLY WINDS IN THE 15 TO 25 KNOT
RANGE OVER THE EAST HALF OF THE LAKE AND IN THE 10 TO 15 KNOT RANGE
OVER THE WEST. AS THE HIGH BUILDS INTO THE WESTERN GREAT LAKES FROM
WED NIGHT INTO FRIDAY WINDS WILL BE RELATIVELY LIGHT...GENERALLY
BELOW 20 KNOTS. AS THE RIDGE SHIFTS TO THE EAST OF THE AREA
SATURDAY...LIGHT TO MODERATE S TO SW WINDS WILL DEVELOP.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1250 PM EDT TUE MAR 26 2013
.AVIATION...
//DISCUSSION...
THE RADAR AND SATELLITE COMPOSITE HAS BEEN SHOWING CONVECTIVE
INSTABILITY ON THE INCREASE. EXPECT THE COVERAGE OF RAIN SHOWERS
WILL INCREASE THROUGH THE AFTERNOON AS A RESULT. SOME OF THE HIGHER
INTENSITY SHOWERS WILL BE CAPABLE OF PRODUCING A BRIEF BURST OF
SNOW. WHILE RESIDUAL LOW LEVEL MOISTURE THIS MORNING LED TO SOME
POCKETS OF MVFR STRATO CU...CLOUD BASES WILL SLOWLY RISE THROUGH THE
AFTERNOON WITH CONTINUED DAYTIME HEATING. CLOUDS WILL DECREASE IN
COVERAGE DURING THE EVENING AS DAYTIME INSTABILITY IS LOST.
OBSERVATIONAL DATA ACROSS ONTARIO /NORTHEAST OF LAKE HURON/ SUGGEST
CONDITIONS ARE MUCH DRIER THAN CURRENT MODEL SOLUTIONS INDICATE.
THIS SUPPORTS HOLDING ANY CEILING ABOVE 6K FT THIS EVENING THROUGH
DAYBREAK WED.
FOR DTW...OCCASIONAL CLOUD BASES BETWEEN 3K AND 5K FT CAN BE
EXPECTED THIS AFTERNOON...ESPECIALLY DURING ANY CONVECTIVE SHOWERS.
THE DEGREE OF DRY AIR NOW OBSERVED UPSTREAM IS SUGGESTIVE OF A GOOD
CHANCE THAT CIGS WILL REMAIN CLEAR BELOW 5K FT TONIGHT INTO EARLY
WED MORNING.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN CEILING BELOW 5000 FEET THIS AFTERNOON AND
EVENING.
&&
.PREV DISCUSSION...ISSUED 1017 AM EDT TUE MAR 26 2013
UPDATE...
THE 12Z DTX SOUNDING SHOWED RATHER STEEP LAPSE RATES IN THE
900-700MB LAYER. BY AFTERNOON...DIURNAL HEATING WILL ONLY STEEPEN
THE LOW LEVEL LAPSE RATES. THE REGIONAL WATER VAPOR LOOP SHOWS A
WEAK MID LEVEL CIRCULATION OVER THE WESTERN GREAT LAKES. THIS
FEATURE WILL SPREAD SOME LARGE SCALE ASCENT ACROSS SE MI THROUGH
EARLY AFTERNOON. THE COMBINATION OF THE WEAK LARCE SCALE LIFT AND
INCREASING DIURNAL INSTABILITY WITHIN A REGION OF AMPLE MID LEVEL
MOISTURE OVER LOWER MI SHOULD SUPPORT FAIRLY GOOD COVERAGE OF
SHOWERS ACROSS A GOOD PORTION OF THE FORECAST AREA THIS AFTERNOON.
THIS WILL BE SUPPORTIVE OF A SLIGHT INCREASE IN POPS THIS
AFTERNOON. THE MORNING DTX SOUNDING ALSO SUGGESTED THAT AFTERNOON
MIXING WILL BOOST TEMPS INTO THE LOWER 40S. THIS LOOKS REASONABLE
GIVEN THERE HAVE BEEN SOME BREAKS IN THE CLOUDS AND GIVEN 10 AM
TEMPS ARE ALREADY IN THE MID-UPPER 30S. THIS SLIGHT UPWARD
ADJUSTMENT TO THE TEMPS /WHICH THE RAP SOUNDINGS SEEM TO HAVE A
BETTER HANDLE ON/ WOULD SUGGEST THAT THE DEPTH OF WARM AIR IN THE
BOUNDARY LAYER WOULD BE SUPPORTIVE OF MAINLY RAIN FOR AFTERNOON
PRECIP TYPE. GIVEN THE CONVECTIVE POTENTIAL...A CHANGE OVER TO
BRIEFLY HEAVY/WET SNOW WOULD STILL BE POSSIBLE. THUS WILL UPDATE
THE FORECAST TO INCREASE AFTERNOON TEMPS AND ADD A MIX OF
RAIN/SNOW TO THE PRECIP TYPE.
PREV DISCUSSION...ISSUED 331 AM EDT TUE MAR 26 2013
SHORT TERM... TODAY AND TONIGHT
RADAR COMPOSITES INDICATE RESPECTABLE COVERAGE OF FLURRIES AND
CLUSTERS OF SNOW SHOWERS OVER LOWER MICHIGAN DURING THE EARLY
MORNING. THE 00Z SOUNDINGS FROM APX AND DTX INDICATE THIS LIGHT
ACTIVITY IS PRIMARILY A RESULT OF BROAD CYCLONIC LOW LEVEL FLOW
WORKING ON STEEP LAPSE RATES OF 7-8 C/KM BELOW 750 MB. CLUSTERS OF
SNOW SHOWERS SLIGHTLY ABOVE A FLURRY EMANATING FROM OVER LAKE HURON
ARE GETTING A BOOST FROM THE RELATIVELY WARM WATER BUT ARE JUST AN
EXTENSION OF ACTIVITY FROM UPSTREAM OVER NORTHERN ONTARIO RATHER
THAN LEGITIMATE LAKE EFFECT. SATELLITE IMAGERY ALSO INDICATES MID
LEVEL CIRCULATION WITHIN THE WEAK UPPER LEVEL TROUGH OVER THE
NORTHERN GREAT LAKES. THIS FEATURE WILL ADD SOME MID LEVEL COOLING
TO THE RATHER SUBSIDENT LOOKING 00Z APX SOUNDING AS THE TROUGH
SETTLES SOUTHWARD OVER LOWER MICHIGAN DURING THE DAY. ADD TO THAT A
COMPONENT OF DIURNAL SURFACE WARMING AND WE CAN EXPECT ONGOING
ACTIVITY TO CONTINUE IF NOT GROW IN COVERAGE BY LATE MORNING THROUGH
THE AFTERNOON. MODEL SOUNDINGS INDICATE THE ABOVE FREEZING LAYER
DEEPENING FROM THE SURFACE TO JUST ABOUT 800 FEET BY MID AFTERNOON
WHICH IS SHALLOW ENOUGH TO ALLOW SNOWFLAKES TO REACH THE SURFACE
WHERE THEY WILL MELT ON CONTACT WITH THE GROUND AS MAX TEMPS MAKE A
RUN TOWARD 40. GIVEN THE EXPECTATION OF ONLY TRACE AMOUNTS OF SNOW
AT ANY ONE LOCATION, THE INHERITED GENEROUS SCATTERED POP FORECAST
LOOKS FINE AND WILL BE CONTINUED IN THIS PACKAGE.
LEFTOVER DIURNALLY ENHANCED SNOW SHOWERS OR FLURRIES WILL LAST INTO
THE EVENING BUT WILL THEN GIVE WAY TO A CHALLENGING CLOUD FORECAST
FOR THE REST OF THE NIGHT. A SIZEABLE SLUG OF DRY AIR OVER WESTERN
QUEBEC/NE ONTARIO AT PRESS TIME WILL LIKELY HAVE A NEGATIVE
INFLUENCE ON THE POTENTIAL FOR STRATOCU MAINTENANCE OVER THE GREAT
LAKES LATER TONIGHT. THIS DRY AIR WILL WORK AGAINST CONTINUED BROAD
CYCLONIC FLOW THROUGH THE LOW LEVELS WITH ENOUGH COLD AIR BELOW 850
MB FOR SOME SIPHONING OF MOISTURE FROM THE LAKES. LOW LEVEL RH
FIELDS IN THE 00Z MODELS EXHIBIT THE USUAL HIGH BIAS IN MOISTURE
CONTENT WHICH MAKES IT A TOUGH CALL ON WHICH PROCESS WILL WIN OUT.
THE FORECAST WILL REFLECT CAUTIOUS OPTIMISM BY CUTTING CLOUD COVER
BELOW MODEL DEPICTIONS BUT STILL MAINTAIN SOME COVERAGE THROUGH
SUNRISE WEDNESDAY.
LONG TERM...WEDNESDAY THROUGH MONDAY
PV ANOMALY ASSOCIATED WITH THE NEWFOUNDLAND UPPER LOW IS STILL
PROGGED BY THE 00Z GUIDANCE TO ROTATE SOUTHWARD ACROSS THE EASTERN
GREAT LAKES LATE ON WEDNESDAY, BRINGING A GLANCING BLOW OF SHALLOW
FORCING FOR ASCENT TO SOUTHEAST MICHIGAN. ULTIMATELY MADE THE
DECISION TO REINTRODUCE POPS FOR LATE WEDNESDAY NIGHT OWING
PRIMARILY TO THE RESPECTABLE MOISTURE CONTENT THAT WILL BE
ASSOCIATED WITH THIS WAVE. 00Z NAM PLANVIEWS DEPICT OF 2 G/KG OF H20
AT H7 AND 3 G/KG AT H85. WHILE NOT PARTICULARLY IMPRESSIVE, THIS
WILL BE SUFFICIENT TO MAINTAIN SATURATION THROUGH ABOUT THE LOWEST
10KFT AND WILL ALSO PROVIDE A BRIEF WINDOW FOR ACTIVATION OF THE
DENDRITE GROWTH LAYER...AT LEAST THE LOWER REACHES OF IT. AS A
RESULT, POPS TAPERING FROM HIGH CHANCE IN THE EASTERN THUMB TO LOW
CHC ACROSS THE CENTRAL/SW CWA ARE NOW IN PLACE ALONG WITH
CATEGORICAL MENTION OF FLURRIES FOR ROUGHLY THE SAME AREA.
A STRONG SURGE OF PACIFIC JET ENERGY WILL DRIVE THE EVOLUTION OF THE
LARGE SCALE NOAM PATTERN FOR THE REMAINDER OF THE LONG TERM PERIOD.
WHAT THIS WILL MEAN LOCALLY IS THAT THE NEXT TWO DAYS WILL BE
CHARACTERIZED BY DECREASING INFLUENCE OF LARGE SCALE MOIST CYCLONIC
FLOW AND THUS INCREASED POTENTIAL TO SEE SOME SUN AND WARMING OF
TEMPERATURES BEGINNING ACROSS THE WEST ON THURSDAY. AS THE UPPER AIR
PATTERN IS PUSHED ALONG BY THE PAC JET, HIGH LATITUDE SHORTWAVE
RIDGING WILL DEAMPLIFY AND PROPAGATE ACROSS THE GREAT LAKES
THURS/FRI RESULTING IN A PATTERN OF RISING HEIGHTS AND A REBOUNDING
THERMAL FIELD. AREAS THAT SEE SUN ON THURSDAY, MOST LIKELY ACROSS
THE FAR WEST/SOUTHWEST WILL SEE TEMPERATURES JUMP INTO THE MID 40S,
WHILE THE REMAINDER OF SEMI WILL HAVE TO WAIT UNTIL FRIDAY WHEN MOST
OF THE AREA WILL SEE MID/UPPER 40S. ANOTHER ROUND OF SHORTWAVE
RIDGING LEADING A RENEWED SURGE OF DRY NW FLOW WILL KEEP THE AREA
DRY THROUGH AT LEAST THE FIRST HALF OF THE WEEKEND AND WILL FORCE
FURTHER WARMTH TO LIFT INTO THE STATE ALLOWING HIGHS TO CLIMB TO
AROUND 50.
THE APPROACH OF THE AFOREMENTIONED PAC JET SURGE WILL BE FELT
STRONGLY SUNDAY INTO MONDAY, FIRST WITH A PERIOD OF RAIN SHOWERS
ASSOCIATED WITH THE INITIAL ROUND OF HEIGHT FALLS ON SUNDAY AND THEN
WITH THE PASSAGE OF A VIGOROUS UPPER TROUGH AS THE JET DIVES OUT OF
NW FLOW ALOFT. MONDAY WILL THEN POTENTIALLY REPRESENT A TRANSITION
DAY THAT WILL SEE THE RETURN OF BELOW NORMAL TEMPERATURES/SNOW
CHANCES. SOLID RUN-TO-RUN CONTINUITY OF THE ECMWF ALONG WITH THE
HIGH AMPLITUDE NATURE OF THE TROUGH AND GRADUAL TREND TOWARD A MORE
VIGOROUS EVOLUTION ALL LEND HIGHER THAN NORMAL CONFIDENCE IN THE
GENERAL ASPECT OF A RETURN TO COOLER WEATHER EARLY NEXT WEEK.
MULTIPLE CYCLES OF THE GFS PROVIDING RESPECTABLE CONTINUITY LATE
THIS WEEKEND INTO EARLY NEXT WEEK PROVIDE AN ADDITIONAL BOOST IN
CONFIDENCE.
MARINE...
LAKE HURON AND LOWER MICHIGAN WILL REMAIN BETWEEN HIGH PRESSURE OVER
THE PLAINS AND LOW PRESSURE OFF THE NEW ENGLAND COAST THROUGH THE
MIDDLE PART OF THE WEEK. THIS WILL MAINTAIN A PERSISTENT NORTHWEST
WIND IN THE 10 TO 15 KNOT RANGE WITH GUSTS TO 20 KNOTS. THE WIND
FIELD WILL VARY IN STRENGTH DURING THIS TIME BUT OVERALL WILL FORCE
WAVES IN EXCESS OF 4 FEET OVER THE SOUTH HALF OF LAKE HURON AT LEAST
THROUGH WEDNESDAY NIGHT. HIGH PRESSURE WILL THEN BE ABLE TO MAKE
SOME EASTWARD PROGRESS INTO THE GREAT LAKES THURSDAY WHICH WILL HELP
IMPROVE MARINE CONDITIONS HEADING INTO THE WEEKEND.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
SANILAC...UNTIL 6 AM THURSDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....SC
UPDATE.......SC
SHORT TERM...BT
LONG TERM....JVC
MARINE.......BT
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
106 PM EDT TUE MAR 26 2013
.SYNOPSIS...
LOW PRESSURE OFF THE NEW ENGLAND COAST WILL MOVE NORTHEAST TODAY
WHILE AN UPPER LEVEL DISTURBANCE MOVES ACROSS NORTH CAROLINA FROM
THE WEST THIS AFTERNOON AND EVENING. STRONG HIGH PRESSURE WILL BUILD
INTO THE AREA FROM THE WEST THROUGH FRIDAY. THE HIGH WILL BE OVER
THE AREA SATURDAY AND MOVE OFF OF THE COAST SUNDAY. A COLD FRONT
WILL APPROACH THE REGION MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1 PM TUESDAY...LATEST VSBY SATELLITE IMAGERY SHOWING
WIDESPREAD STRATOCUMULUS ACROSS THE REGION. NAM12 HAS BACKED OFF
THE LIGHT PRECIP FOR THE AFTERNOON...BUT THE RAP AND LATEST 4 KM
WRF MODELS STILL CONTINUE TO SHOW SPOTTY LIGHT SPRINKLES AND
SHOWERS AND HAVE A SLIGHT CHC POP OVER MOST AREAS THROUGH 00Z.
AMOUNTS WILL BE VERY LIGHT WHERE MEASURABLE...AT PERHAPS A
HUNDREDTH OR TWO. WITH THE CLOUDY SKIES...MAX TEMPERATURES WILL NOT
GO UP MUCH MORE THAN CURRENT LEVELS IN THE UPPER 40S TO AROUND 50.
OTHER THAN THE POPS...NO MAJOR CHANGES TO FORECAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
AS OF 330 AM TUESDAY...SCT-BKN SCU WITH PSBL ISOLD SHOWERS WILL
LINGER INTO EARLY EVENING...THEN DECREASING CLOUDS EXPECTED WITH
LOSS OF HEATING. SECONDARY CAA SURGE FOLLOWING SHRT WV EXPECTED TO
PRODUCE ENOUGH WIND TO PRECLUDE DECOUPLING OVERNIGHT...BUT CONTINUED
SLIGHT COOLING OF AIR MASS WILL SUPPORT MIN TEMPS IN LOW-MID 30S
INLAND WITH UPR 30S OBX. NW HALF OF ONSLOW COUNTY...WHERE GROWING
SEASON IS IN EFFECT...COULD SEE LOWS AROUND 32...BUT WILL LET DAY
SHIFT TAKE A LOOK AT PSBL NEED FOR FREEZE WARNING THERE.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 3 AM TUE...A SLOW WARMING TREND IS IN STORE FOR THE EXTENDED
PERIOD DUE TO A STEADILY CHANGING SURFACE PATTERN. THE LARGE
CYCLONIC FLOW AROUND THE DEEP LOW FAR TO THE NORTHEAST WILL SLOWLY
BE REPLACED BY A SURFACE RIDGE BUILDING IN FROM THE WEST. THE HIGH
WILL BE CENTERED OVER THE AREA FRIDAY AND SATURDAY. THE HIGH WILL
MOVE OFF THE SOUTHEAST COAST SUNDAY. THE NEXT FRONT WILL APPROACH
FROM THE NORTHWEST MONDAY. HIGH TEMPS WEDNESDAY WILL BE IN THE
LOWER 50S...WARMING TO THE MID/UPPER 60S BY EARLY NEXT WEEK. ONLY
PRECIP IN THE FORECAST WILL BE A CHANCE OF SHOWERS SUNDAY NIGHT
AND MONDAY ASSOCIATED WITH THE APROACHING FRONT.
NOTE: GROWING SEASON WILL BEGIN ON WEDNESDAY FOR REST OF FORECAST
AREA...AND FREEZE WATCH/WARNING MAY BE NEEDED FOR INLAND SECTIONS
WED NIGHT/THU MORNING.
&&
.AVIATION /17Z TUESDAY THROUGH SATURDAY/...
SHORT TERM /THROUGH 12Z WEDNESDAY/...
AS OF 1 PM TUESDAY...WIDESPREAD 5000-6000 FT STRATOCUMULUS WILL
CONTINUE THROUGH LATE AFTERNOON BUT SHOULD DISSIPATE WITH LOSS OF
HEATING TONIGHT. VFR CONDITIONS TO CONTINUE.
LONG TERM /WED THRU SAT/
AS OF 3 AM TUE...VFR WITH MOSTLY CLEAR SKIES AND A LIGHT NORTHWEST
FLOW THROUGH THE PERIOD.
&&
.MARINE...
SHORT TERM /THROUGH TONIGHT/...
AS OF 1 PM TUESDAY...SMALL CRAFT ADVISORIES HAVE EXPIRED OVER THE
PAMLICO SOUND AND TWO SOUTHERN LEGS. THEY WILL REMAIN IN EFFECT
FOR THE NEXT HOUR OR SO SLOWLY...BUT WITH THE BUOY 13 MILES EAST
OF OREGON INLET STILL HOVERING AROUND 6 FEET...MAY EXTEND THE SCA
SHORTLY.
LONG TERM /WED THRU SAT/
AS OF 3 AM TUE...LATEST RUN OF THE GFS AND ECMWF SHOWS THEM IN
GOOD AGREEMENT. USED A CONSENSUS BLEND FOR THE FORECAST. NORTHWEST
FLOW WILL CONTINUE OVER THE AREA. CYCLONIC FLOW AROUND DEEP LOW
FAR TO THE NORTHEAST WILL GRADUALLY GIVE WAY TO A SURFACE RIDGE
BUILDING IN FROM THE WEST THROUGH THE WEEKEND. WINDS AND SEAS
WILL SLOWLY SUBSIDE AS A RESULT.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EDT WEDNESDAY FOR AMZ150-152-
154.
&&
$$
SYNOPSIS...JBM
NEAR TERM...CTC
SHORT TERM...JBM
LONG TERM...HSA
AVIATION...CTC/HSA
MARINE...CTC/HSA
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SYNOPSIS...
ISSUED AT 229 PM CDT TUE MAR 26 2013
QUIET WEATHER WITH MODERATING TEMPERATURES THE REST OF THE WORK
WEEK...SOME LIGHT PRECIPTIATION THIS WEEKEND...THEN PROBABLY
COLDER AGAIN NEXT WEEK.
THE BLOCKING ACRS THE CONUS WL EASE DURING THE PERIOD...WITH LOW
AMPLITUDE WNWLY UPR FLOW BECOMING RE-ESTABLISHED. BUT THE FLOW AT
HIGHER LATITUDES WL REMAIN BLOCKY. THE BREAK DOWN OF THE MIDDLE
LATITUDE BLOCKING WL ALLOW W TO E PROGRESSION OF WX SYSTEMS TO
RESUME...AND TEMPERATURES TO MODERATE BACK TO NEAR OR EVEN A
LITTLE ABOVE SEASONAL NORMALS. BUT IT WL BE TOUGH TO GET ANY
PROLONGED SIGNIFICANT WARMING AS LONG AS HIGH LATITUDES ARE
BLOCKED...AND ANOTHER SHOT OF CHILLY CANADIAN AIR IS LIKELY TO
OVERSPREAD THE AREA EARLY NEXT WK. THE PATTERN LOOKS UNFAVORABLE
FOR SIG PCPN.
&&
.SHORT TERM...TONIGHT AND WEDNESDAY
ISSUED AT 229 PM CDT TUE MAR 26 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW SHORTWAVE
ACTIVITY PROGRESSING SOUTH ACROSS MUCH OF CENTRAL AND SOUTHERN
WISCONSIN. DEEP CYCLONIC FLOW AND COLD TEMPS ALOFT HAVE MAINTAINED
A WIDESPREAD VFR CLOUD DECK FROM NORTHERN ILLINOIS/INDIANA TO
WESTERN ONTARIO. FLURRY ACTIVITY MOVED OUT OF THE AREA FOR THE MOST
PART BY LATE IN THE MORNING...BUT DIURNAL INSTABILITY GENERATED SCT
SNOW SHOWERS EARLY THIS AFTERNOON ACROSS MUCH OF THE AREA. THINK
MUCH OF THE SNOW SHOWERS WILL DISSIPATE WITH LOSS OF HEATING LATE
THIS AFTERNOON OR EARLY THIS EVENING...BUT WILL KEEP A MENTION OF FLURRIES
GOING THROUGH 01Z. DRIER AIR IS MOVING SE OVER EASTERN UPPER
MICHIGAN AND LAKE SUPERIOR...AND IS APPROACHING NORTHERN LAKE
MICHIGAN EARLY THIS AFTERNOON. BESIDES THE SNOW SHOWERS...CLOUD
TRENDS ARE THE MAIN FORECAST CONCERN.
TONIGHT...THE SHORTWAVE TROUGH WILL MOVE SOUTHEAST OVER THE
SOUTH-CENTRAL GREAT LAKES TOWARDS THE OHIO VALLEY. CHALLENGING
CLOUD FORECAST TONIGHT...WHICH WILL IMPACT TEMPS. MID-LEVEL HEIGHT
RISES WILL ONLY BE MODEST THIS EVENING...SO NOT ANTICIPATING A FAST
CLEARING TREND. ADVECTION OF DRIER AIR FROM THE NORTHEAST AND ALSO
FROM HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CAUSE THE MID-LEVEL
MOISTURE RIBBON TO BECOME STRETCHED ACROSS NORTHEAST WISCONSIN
TONIGHT. AS A RESULT...THINK CLOUDS SHOULD THIN AS HOLES DEVELOP
THROUGH THE NIGHT. CLOUDS TO HANG A BIT LONGER OVER N-C WISCONSIN
WHERE FLOW REMAINS OFF LAKE SUPERIOR. IN THE END...MOSTLY CLOUDY
THIS EVENING TO BECOME PARTLY CLOUDY OVERNIGHT. IF SKY CLEARS OUT
QUICKER...TEMPS WILL FALL LOWER THAN CURRENTLY PLANNED. WILL GO
WITH LOWS IN THE MID TEENS OVER THE COLD SPOT OF CENTRAL
WISCONSIN...TO THE MID 20S NEAR LAKE MICHIGAN.
WEDNESDAY...WILL STILL HAVE CYCLONIC FLOW THROUGH THE COLUMN
TOMORROW...ALONG WITH AMPLE LOW LEVEL MOISTURE. AS LOW LEVEL LAPSE
RATES STEEPEN WITH MORE IN THE WAY OF SUNSHINE...SHOULD SEE
LINGERING CLOUD COVER BECOME ENHANCED THROUGH DIURNAL TEMPS RISES BY LATE
MORNING TO EARLY AFTERNOON. TEMPS ALOFT WILL BE SIMILAR TO
TODAY...BUT SHOULD SEE MORE SUNSHINE...SO WILL GO WITH TEMPS MAYBE A
DEGREE WARMER THAN TODAY.
.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY
ISSUED AT 229 PM CDT TUE MAR 26 2013
QUIET FOR THE REST OF THE WORK WEEK AS HIGH PRESSURE RIDGING SWD
FM CANADA CONTROLS THE WX ACRS THE AREA. MODERATION OF THE AIR
MASS SHOULD YIELD A LITTLE WARMING EACH DAY...ESP ONCE LOW-LEVELS
DRY OUT A BIT MORE AND THERE ARE FEWER CLDS.
STILL LOOKS LIKE THERE IS A CHC FOR PCPN WITH SHRTWV CROSSING THE
AREA THIS WEEKEND. LATER SAT AND SAT NGT SEEM TO BE MOST FAVORED
TIME PERIOD. BUT WITH LIMITED MOISTURE AND MODEST FORCING AT
BEST...PCPN AMNTS WL BE LIGHT AND SOME AREAS MAY MISS OUT ON THE
PCPN COMPLETELY.
UPR VORTEX DIGGING ESE THROUGH THE LAKE SUPERIOR RGN COULD BRING
ANOTHER BATCH OF LGT PCPN LATE IN THE WEEKEND OR EARLY NEXT WK.
BUT IT/S MAIN INFLUENCE WL BE TO USHER ANOTHER COLD AIR MASS INTO
THE AREA.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1231 PM CDT TUE MAR 26 2013
SCT FLURRY ACTIVITY WILL DIMINISH THIS AFTERNOON WHEN AN
UPPER LEVEL DISTURBANCE DEPARTS TO THE SOUTHEAST. MID-LEVEL CLOUD
DECK WILL HANG AROUND LONGER...AND TIMING OF THE ARRIVAL OF CLEARING
IS NOT CLEAR-CUT. DRIER AIR IS WORKING INTO THE REGION FROM THE
NORTHEAST...AND INCREASING SUBSIDENCE BEHIND THE UPPER LEVEL
DISTURBANCE POINTS TOWARDS A SLOW CLEARING TAKING PLACE THIS EVENING
INTO THE OVERNIGHT HOURS. LOW LEVEL FLOW WILL REMAIN OFF LAKE
SUPERIOR...SO ANTICIPATE CLOUDS HANGING AROUND THROUGH THE REST OF
THE TAF PERIOD OVER FAR N-C WISCONSIN. DESPITE THE CLOUD
COVER...MAINLY VFR CONDITIONS THROUGH LATE MORNING TOMORROW.
DIURNAL CU TO BUILD MIDDAY TOMORROW DUE TO STEEP LOW LEVEL LAPSE
RATES.
&&
.HYDROLOGY...
ISSUED AT 229 PM CDT TUE MAR 26 2013
CONDITIONS FOR A FAST SNOWMELT NOT ON THE RADAR FOR
MOST OF THE WORK WEEK...WITH CONTINUED DRY WEATHER AND COOL
TEMPERATURES PERSISTING. HOWEVER...THERE STILL WILL BE A GRADUAL
EROSION OF THE SNOWPACK WITH TEMPERATURES CLIMBING ABOVE THE
FREEZING MARK EACH DAY. RUNOFF POTENTIAL FROM SNOW MELT INCREASES
FOR NEXT WEEKEND WITH FORECAST TEMPERATURES CLIMBING TO THE LOWER
TO MIDDLE 40S ON FRIDAY/SATURDAY/SUNDAY. OVERNIGHT LOW TEMPERATURES
SATURDAY NIGHT ONLY FALL TO THE FREEZING MARK OVER EAST CENTRAL
WISCONSIN AHEAD OF A WEAK COOL FRONT TO KEEP THE SNOWMELT
PARTIALLY GOING. WITH THIS SCENARIO...THE MAIN AFFECTS OF RUNOFF
COULD PRODUCE SOME PONDING OF WATER...AND A RISE IN THE RIVERS
OVER CENTRAL AND EAST CENTRAL WISCONSIN LATE NEXT WEEKEND. RAIN
OR MIXED PCPN MAY ALSO OCCUR THIS WEEKEND WITH THE FRONT...BUT
PCPN AMOUNTS LOOK LIKE THEY WILL BE FAIRLY LIGHT AT THIS TIME.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS.......SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......SKOWRONSKI
AVIATION.......MPC
HYDROLOGY......MPC