Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 11/21/12
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
830 PM EST TUE NOV 20 2012
.UPDATE (TONIGHT AND WEDNESDAY)...
01Z WATER VAPOR AND H4 RAP ANALYSIS SHOW AN AMPLIFIED NORTHERN
STREAM FLOW ACROSS THE CONUS. JET ENERGY ARRIVES OVER THE PACIFIC
NORTHWEST BEFORE RIDGING OVER THE INTER-MOUNTAIN WEST AND PLAINS
STATES. THE FLOW THEN DIVES BACK TO THE SOUTHEAST INTO LONGWAVE
TROUGHING COVERING THE EASTERN THIRD OF THE CONUS. IMPRESSIVE
SHORTWAVE CAN BE SEEN MOVING DOWN THE BACKSIDE OF THIS LARGER TROUGH
WITH AN AXIS NOW CURRENTLY MOVING THROUGH THE SOUTHERN MS VALLEY
TOWARD THE NORTHEAST GULF COAST. 21/00Z KTBW SOUNDING SHOWS A
GENERALLY DRY PROFILE WITH A PW VALUE OF ONLY AROUND 0.8". WE HAVE
SEEN SOME DECENT SYNOPTIC COOLING IN THE MID-LEVELS DURING THE PAST
24 HOURS WITH THE APPROACH OF THE SHORTWAVE FEATURE MENTIONED ABOVE.
AT THE SURFACE...A GENERAL NORTHERLY FLOW IS OBSERVED WITHIN THE
GRADIENT BETWEEN AN ELONGATED AREA OF LOW PRESSURE OVER THE WESTERN
ATLANTIC...AND CONTINENTAL HIGH PRESSURE THROUGH THE MID-SECTION OF
THE COUNTRY. SEASONABLY COOL TEMPERATURES IN PLACE LATE THIS EVENING
WITH UPPER 50S TO LOWER 60S COMMON.
THE SHORTWAVE ENERGY APPROACHING THE REGION IS ACTUALLY A FAIRLY
POTENT FEATURE. FORECAST HEIGHT FALLS AND SYNOPTIC/QG FORCING
ASSOCIATED WITH ITS APPROACH AND PASSAGE WOULD AT FIRST GLANCE
SUGGEST THE NEED FOR AT LEAST SOME SHOWERS IN THE FORECAST.
HOWEVER...THE COLUMN APPEARS SIMPLY TOO DRY TO SUPPORT MUCH MORE
THAN POTENTIALLY A FEW ISOLATED SPRINKLES...AND MAINLY NORTH OF
TAMPA BAY UP TOWARD THE BIG BEND REGION. IT IS OVER THESE FAR
NORTHERN COUNTIES WHERE THE BEST DEEP LAYER QG FORCING WILL PASS.
HAVE ACTUALLY SEEN A FEW SPRINKLES UP TOWARD THE FL
PANHANDLE/SOUTHERN GA THIS EVENING ASSOCIATED WITH THIS
FORCING...BUT SO FAR HAVE NOT SEEN ANYTHING WITH VISIBILITIES LESS
THAN 10SM. BASED ON PRESENT TRENDS WILL ADD A 10% POP FOR BRIEF
SPRINKLES OVERNIGHT UP TOWARD LEVY COUNTY...HOWEVER THESE WILL BE OF
VERY LOW TO NO IMPACT WITH RESPECT TO OUTDOOR ACTIVITIES. WOULD BE
VERY SURPRISED IF ANY MEASURABLE PRECIP IS OBSERVED. FURTHER SOUTH
TOWARD THE TAMPA BAY AREA ONLY EXPECTING SOME INCREASE IN
CLOUDS...AND BASICALLY NO OVERNIGHT IMPACT DOWN TOWARD PUNTA
GORDA/FT MYERS.
WEDNESDAY...SHORTWAVE ENERGY AND A WEAK SURFACE BOUNDARY WILL SWING
ACROSS THE AREA. MAY STILL SEE A FEW ISOLATED SPRINKLES AROUND
DURING THE MORNING TO THE NORTH OF TAMPA BAY...BUT NWP GUIDANCE ALL
SHOWING THE BEST SYNOPTIC LIFT PASSING TO OUR EAST BY AFTERNOON.
DEEP LAYER DRY AIR WILL QUICKLY ADVECT OVER REGION BEHIND THIS
SHORTWAVE FOR THE END OF THE WEEK. MORE DETAILS ON THE THANKSGIVING
HOLIDAY IN THE PREVIOUS DISCUSSION BELOW.
&&
.PREVIOUS DISCUSSION (WEDNESDAY NIGHT - THURSDAY)...
UPPER AND SURFACE RIDGING WILL BUILD IN OVER THE EASTERN U.S. WITH
PLEASANT DRY COOL WEATHER EXPECTED UNDER MOSTLY CLEAR SKIES. A
TIGHTENING GRADIENT BETWEEN DEEPENING LOW PRESSURE OVER THE ATLANTIC
AND THE HIGH WILL SUPPORT BREEZY CONDITIONS ACROSS THE REGION.
TEMPERATURES WILL RUN A FEW DEGREES BELOW NORMAL TONIGHT AND
WEDNESDAY...THEN SOME 3 TO 5 DEGREE BELOW NORMAL DURING WEDNESDAY
NIGHT AND THURSDAY AS THE COOLER DRIER AIR MOVES INTO THE REGION.
DAYTIME HIGHS ON WEDNESDAY WILL CLIMB TO LOWER 70S NORTH...AND LOWER
TO MID 70 CENTRAL AND SOUTH THEN AROUND 70 NORTH...AND LOWER 70S
CENTRAL AND SOUTH ON THANKSGIVING DAY. OVERNIGHT LOWS IN THE UPPER
40S TO LOWER 50S NORTH AND LOWER TO MID 50S CENTRAL AND SOUTH
TONIGHT WILL FALL TO AROUND 40 ACROSS THE NORTH...AND MID TO UPPER
40S CENTRAL AND SOUTH WEDNESDAY NIGHT INTO THANKSGIVING MORNING.
&&
.AVIATION...
A DEEPENING REINFORCING TROUGH WILL PASS THE AREA OVERNIGHT BRINGING
IN SOME MID AND HIGH CLOUDS THAT WILL PASS SOUTHWARD DOWN THE
PENINSULA TONIGHT AND TOMORROW MORNING.
&&
.MARINE...
A NORTH TO NORTHEAST WIND FLOW AROUND 15 KNOTS WITH SEAS OF 2 TO 4
FEET WILL PERSIST OVER THE GULF WATERS THROUGH EARLY WEDNESDAY
MORNING. WIND AND SEAS WILL LIKELY INCREASE INTO THE EXERCISE
CAUTION RANGE (15 TO 20 KNOTS) WEDNESDAY AFTERNOON THROUGH
THANKSGIVING DAY IN THE WAKE OF A COLD FRONT. LIGHTER WIND AND SEAS
WILL RETURN TO THE WATERS FRIDAY THROUGH EARLY SATURDAY AS HIGH
PRESSURE BUILDS IN OVER THE NORTHERN GULF. WIND AND SEAS WILL AGAIN
INCREASE TOWARD EXERCISE CAUTION VALUES LATE SATURDAY INTO SUNDAY AS
YET ANOTHER COLD FRONT SWEEPS SOUTH THROUGH THE WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 56 75 52 73 / 0 0 0 0
FMY 57 76 53 74 / 0 0 0 0
GIF 54 73 50 73 / 10 0 0 0
SRQ 56 75 53 74 / 0 0 0 0
BKV 50 74 41 72 / 0 0 0 0
SPG 59 73 59 72 / 0 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE...MROCZKA
PREVIOUS DISCUSSION...MCMICHAEL
AVIATION...PAXTON
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
922 PM CST TUE NOV 20 2012
.DISCUSSION...
922 PM CST
HAVE EXPANDED THE DENSE FOG ADVISORY TO INCLUDE THE REMAINDER OF
THE FORECAST AREA...INCLUDING ALL OF CHICAGO...AS OBSERVATIONAL
GUIDANCE CONTINUES TO FALL IN LINE WITH THE IDEAL SYNOPTIC AND
MESOSCALE PATTERNS FOR DENSE FOG.
NOT MUCH TO ADD FROM PREVIOUS REASONING IN DISCUSSIONS BELOW. THE
00Z DVN SOUNDING REVEALED A CLASSIC FOG SOUNDING GOING INTO THE
EVENING. THE AREA OF PERSISTENT DENSE FOG CENTERED ON THE
MISSISSIPPI RIVER CONTINUES TO EXPAND EASTWARD...LINING UP WITH
THE SURFACE RIDGE AXIS PERFECTLY. OFF OF LAKE MICHIGAN INTO
NORTHWEST IN/SOUTHWEST MI...DENSE FOG HAS DEVELOPED/EXPANDED
INLAND DUE LIKELY TO SLIGHTLY HIGHER MOISTURE...ALTHOUGH IT SEEMS
PATCHY TO AREAS AT TIMES BASED ON WEBCAMS AND REPORTS. AS FOR
IN-BETWEEN THESE TWO PRONOUNCED AREAS...THE ATMOSPHERE SHOULD
CONTINUE TO SATURATE AND FORECAST SOUNDINGS INDICATE DENSE FOG
FOR MUCH OF THE OVERNIGHT AND INTO WEDNESDAY MORNING. SOME CONCERN
THIS FOG COULD LAST ALL THE WAY TO NOON. NO MATTER WHAT...THIS
WILL HAVE IMPACTS ON ANY EARLY TO MID MORNING HOLIDAY TRAVELERS.
IN ADDITION...HAVE FURTHER STIFLED THE TYPICAL DIURNAL TEMPERATURE
INCREASE WEDNESDAY MORNING...AND LOWERED HIGH TEMPERATURES BY 2-3
DEGREES. THESE MAY END UP NEEDING TO BE LOWERED MORE...AS THE LATE
NOVEMBER LOW SUN ANGLE WILL HAVE SOME DIFFICULTY ERODING THIS FOG.
MTF
&&
.PREV DISCUSSION...
628 PM CST
HAVE SPED UP THE START TIME OF THE DENSE FOG IN THE FORECAST...AND
WITH FURTHER INCREASED CONFIDENCE ON THE AREA TO MOST LIKELY BE
IMPACTED...HAVE GONE AHEAD AND ISSUED A DENSE FOG ADVISORY FOR
NORTH CENTRAL ILLINOIS AND FAR WESTERN AND NORTHERN AREAS OF THE
CHICAGO METROPOLITAN AREA. THIS MAY VERY WELL NEED TO BE EXPANDED
IN TWO TO THREE HOURS.
WINDS HAVE BECOME CALM OR LIGHT AND VARIABLE ACROSS THE ENTIRE
AREA EARLY THIS EVENING AS THE RIDGE AXIS HAS EXPANDED INTO
NORTHERN IL. DEW POINTS REMAIN ANOMALOUSLY HIGH WITH MID 40S...AND
TEMPERATURE DROPS AT A HANDFUL OF SITES HAVE BEEN AROUND OR EVEN
HIGHER THAN 10F SINCE 4 PM. THIS HAS RESULTED IN T/TD SPREADS OF
LESS THAN 5F ALREADY ACROSS NORTH CENTRAL IL. IN ADDITION..THE
AREAS OF FOG THAT PERSISTED THROUGH TODAY IN EASTERN IA/FAR
SOUTHWEST WI THAT WERE MENTIONED IN THE PRIOR DISCUSSION HAVE ONLY
BLOSSOMED SINCE SUNDOWN. VISIBILITY OBSERVATIONS IN THESE AREAS
ARE ALMOST ALL AT ONE QUARTER MILE OR LESS. SO WITH THE RIDGE AXIS
ONLY FURTHER TRANSITIONING OVER THE AREA THROUGH LATE
EVENING...WOULD EXPECT VISIBILITY TO DROP AND ESPECIALLY RAPID IN
THOSE AREAS WHERE THE PERSISTING FOG EXPANDS IN /WESTERN WINNEBAGO
AND OGLE COUNTIES BY 830 PM/. THE HRRR FORECAST VISIBILITY AGREES
WITH THIS IDEA OF EASTWARD EXPANSION THROUGH LATE EVENING AND
OVERNIGHT.
AS FOR AREAS TO THE EAST...INCLUDING MUCH OF
CHICAGOLAND...WIDESPREAD 3-6 SM VISIBILITIES EXIST. THESE
VISIBILITIES AND WEBCAMS HAVE INDICATED VERY GRADUAL VISIBILITY
REDUCTION SINCE SUNDOWN. LINGERING CLOUDS AND ASSOCIATED MOIST
LAYER AROUND 3K FT ARE LIKELY IMPAIRING FULL RADIATIONAL COOLING
SOMEWHAT...BUT DO FULLY EXPECT THESE AREAS TO COOL MORE QUICKLY
AND DENSE FOG AT LEAST IN PLACES TO DEVELOP. AREAS NEAR THE LAKE
MAY ACTUALLY BECOME MORE FAVORED TO SEE THE FOG MORE QUICKLY DUE
TO A LIGHT BUT MOIST ONSHORE COMPONENT.
IMPROVEMENT IN THE FOG ON WEDNESDAY MORNING MAY BE EXTREMELY
SLOW...WITH SOME AREAS OF FOG LASTING INTO THE EARLY AFTERNOON
GIVEN WHAT OCCURRED UPSTREAM IN EASTERN IOWA TODAY AND JUST THE
CLIMATOLOGY OF THIS TIME OF YEAR. WILL FURTHER ASSESS THIS WITH
00Z GUIDANCE.
MTF
//PREV DISCUSSION...
256 PM CST
TONIGHT THROUGH WEDNESDAY...
GREATEST CONCERN FOR TONIGHT RESIDES WITH THE EXPECTED DEVELOPMENT
OF FOG...TRANSITIONING INTO AREAS OF DENSE FOG OVERNIGHT. THE
OTHER CONCERN IS THAT ONE OF THE BUSIEST TRAVEL DAYS OF THE YEAR
WILL HAVE A SLOW START GIVEN THE EXPECTED DEVELOPMENT OF FOG.
LOOKING UPSTREAM ACROSS EASTERN IOWA FOG HAS LINGERED INTO THIS
AFTERNOON...WITH A FEW LOCATIONS STILL SEEING VSBYS DOWN AROUND 1 TO
2 MILES. THIS AFTN HAS SEEN ALMOST NO MIXING WITH LGT WINDS
GENERALLY LESS THAN 5 MPH...AND DEW POINTS HOLDING UP IN THE MID 40S
FOR MANY LOCATIONS OF NORTHERN IL/NORTHWEST IN. HIGH PRESSURE WILL
REMAIN OVERHEAD TONIGHT...WHICH WILL AID IN DECENT RADIATIONAL
COOLING SHORTLY AFTER SUNSET. THIS ALL POINTS TOWARDS A REPEAT NIGHT
OF AREAS OF FOG AND POTENTIALLY AREAS OF DENSE FOG. OVERNIGHT LOWS
WILL COOL INTO THE LOW 40S...WITH THE EXCEPTION OF AREAS ADJACENT TO
LAKE MICHIGAN WHERE TEMPS MAY HOLD IN THE MID 40S.
ONCE THE FOG DOES DEVELOP IT WILL MOST LIKELY LINGER INTO WED
MORNING...POSSIBLY THROUGH MIDDAY. GIVEN THE SCENARIO OF WHAT HAS
TRANSPIRED ACROSS EASTERN IOWA...COULD SEE THE DENSE FOG LIFT BY
MID-MORNING THEN PATCHY FOG THROUGH NOON. THIS WILL RESULT IN
TEMPERATURES BEING SLOW TO WARM...THUS HAVE SLOWED THE RATE OF CLIMB
UNTIL MIDDAY. THROUGHOUT THE MORNING HOURS TEMPS WILL REMAIN IN THE
LOW/MID 40S...THEN BY MIDDAY AND IMPROVING VSBYS OR BURNING OFF
FOG...TEMPS WILL BEGIN TO CLIMB RAPIDLY INTO THE UPR 50S AND
POSSIBLY 60 DEG IN A FEW LOCATIONS. OTHERWISE SKIES WILL BECOME
MOSTLY CLEAR IN THE AFTERNOON HOURS.
CONFIDENCE...HIGH.
CONFIDENCE ON AREAS OF DENSE FOG...MEDIUM/HIGH.
THANKSGIVING...
500MB RIDGE REMAINS OVERHEAD...WITH A POTENT THERMAL RIDGE AT 850MB
OF 10 TO 12 DEG C. A FEW ENSEMBLE MEMBERS SUGGEST THAT 850MB TEMPS
COULD BE SLIGHTLY WARMER TO 14 DEG C. THE BETTER PRESSURE GRADIENT
REMAINS DISPLACED TO THE NORTHWEST OF THE REGION...WHICH IS THE AREA
THAT WILL SEE THE STRONGEST WARM AIR ADVECTION. EITHER WAY...IT
APPEARS THANKSGIVING WILL END UP BEING A RATHER WARM DAY WITH TEMPS
LIKELY TO REACH THE LOW 60S. PLUMES CONTINUE TO INDICATE A HIGH
CONFIDENCE THAT TEMPS WILL EASILY PUSH TO 60 DEGREES BY NOON. THE
LARGEST CAVEAT COULD BE THAT INCREASED MOISTURE APPEARS TO BE
PROGGED TO POOL ALONG THE BOUNDARY INTO THE MID-MISSISSIPPI
VALLEY...WHICH COULD PUSH CLOUDS OVERHEAD BY LATE MORNING. THIS
MAINLY WILL AFFECT THE WESTERN HALF OF THE CWFA. IN ADDITION HAVE
OVERSPREAD A SLIGHT CHC OF PRECIP BY MIDDAY ALONG AND NORTH OF A LA
SALLE TO CRYSTAL LAKE LINE. THEN ADDITIONAL MOISTURE CONTINUES TO
POUR INTO THE CWFA BY MID-AFTERNOON/EVENING...SO HAVE MAINTAINED
MENTION OF SLT CHC OF RA.
CONFIDENCE IN TEMPS...HIGH.
CONFIDENCE IN PRECIP...LOW.
FRIDAY THROUGH MONDAY...
ENSEMBLES THROUGH THE EXTENDED PERIODS CONTINUE TO SHOW MINIMAL
SPREAD IN ENVELOPE OF SOLUTIONS...LEADING TO THE INCREASED
CONFIDENCE THAT A PATTERN CHANGE IS UPON US. FRIDAY WILL KICK OFF
THE EXTENDED WITH A TASTE OF COLDER AIR...HOWEVER WHAT APPEARS TO BE
TAKING SHAPE FOR MID/LATE NEXT WEEK WILL BE MUCH MORE SIGNIFICANT AS
THE CALENDAR APPROACHES THE FIRST OF DECEMBER.
GUIDANCE CONTINUES TO PROG FRONTAL PASSAGE FOR THE FIRST HALF OF
FRI...POSSIBLY PRIOR TO DAYBREAK. VERY TIGHT PRESSURE GRADIENT IS
ALSO POISED TO ARRIVE BEHIND THE FRONTAL PASSAGE FRI...RESULTING IN
BREEZY CONDITIONS. WITH COOLER AIR STEADILY ADVECTING IN FROM THE
NORTHWEST AS A RESULT OF AN 850MB THERMAL TROUGH OF -10 TO -14 DEG
C...MAX TEMPS FRI COULD BE ACHIEVED PRIOR TO MID-MORNING. THEN IT
APPEARS FALLING TEMPS WILL OCCUR EARLY IN THE AFTERNOON. AT THIS
TIME IT APPEARS A DRY WEDGE WILL OCCUR FRI...SHIFTING ANY MOISTURE
EAST OF THE CWFA. THEN THE TRANSITION TOWARDS LAKE EFFECT PRECIP
DEVELOPS FRI AFTERNOON THROUGH SATURDAY EVENING...WHICH FORTUNATELY
WITH A STRONG WEST/NORTHWEST FLOW THIS PRECIP WILL BE DISPLACED
DOWNSTREAM ACROSS LOWER MICHIGAN AND PERHAPS PORTIONS OF NORTHWEST
INDIANA.
SAT/SUN WILL SEE ANTI-CYCLONIC FLOW PUSH BACK OVERHEAD WITH DRY
WEATHER EXPECTED THROUGH THE WEEKEND INTO EARLY MON. 500MB TROUGH
PIVOTS EAST WITH A RELATIVELY FLAT OR SEMI-ZONAL FLOW SUN/MON. SAT
HIGH TEMPS WILL STRUGGLE TO WARM INTO THE MID/UPR 30S. SUN/MON WILL
BEGIN TO WARM MARGINALLY INTO THE LOW 40S. THIS ALL APPEARS TO BE
TEMPORARY AS THE DEVELOPMENT OF A BLOCKING PATTERN BEGINS TO TAKE
SHAPE OVER ALASKA AND THE NORTH ATLANTIC...WHICH WILL ULTIMATELY
ALLOW MUCH COLDER AIR TO ARRIVE INTO CENTRAL CANADA MID/LATE NEXT
WEEK FROM SIBERIA.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* LIGHT AND VARIABLE WINDS TONIGHT...BECOMING SOUTH/SOUTHWEST
WEDNESDAY.
* IFR FOG/VIS LIKELY IN THE NEAR TERM...WITH LIFR FOG/VIS LIKELY
OVERNIGHT THROUGH WEDNESDAY MORNING.
RODRIGUEZ
//DISCUSSION...UPDATED 00Z...
MAIN CONCERN THIS FORECAST PERIOD IS IN THE NEAR TERM AND
OVERNIGHT WITH FOG/LOW VIS TO AFFECT ALL OF THE TERMINALS. AS
CLOUD COVER CONTINUES TO EXIT THE AREA...COOLER CONDITIONS IN A
RATHER MOIST ENVIRONMENT AND LIGHT WINDS ARE HELPING FOG TO
QUICKLY DEVELOP EARLY THIS EVENING. THERE IS CURRENTLY VIS OF
3-5SM ACROSS MOST OF THE TERMINALS WITH MDW CURRENTLY SHOWING VIS
OF AROUND 2SM. EXPECT THIS 3-5SM TO BE THE PREVAILING CONDITIONS
OVER THE NEXT COUPLE OF HOURS BEFORE CONDITIONS CONTINUE TO
DETERIORATE TONIGHT. VIS OF 1-2SM WILL THEN BE EXPECTED BEFORE AN
EXPANDING AREA OF MORE DENSE FOG...CURRENTLY ACROSS WESTERN
ILLINOIS...EXPANDS FURTHER TO THE EAST. THIS EXPANDING FOG WILL
THEN LIKELY BRING VIS OF LESS THAN 1SM...WITH THESE CONDITIONS
EXPECTED TO REMAIN THROUGH THE MORNING HOURS ON WEDNESDAY.
CONFIDENCE IS GROWING OF THIS LOWER VIS BUT WITH SOME UNCERTAINTY
REMAINING AS TO THE OVERALL TIMING...AS I HAVE CONTINUED TO PUSH
UP THE TIMING OF THE MORE DENSE FOG WITH LATEST TRENDS.
UNCERTAINTY ALSO REMAINS AS TO THE OVERALL DURATION INTO WEDNESDAY
MORNING...BUT WITH SOME IMPROVEMENT EXPECTED BY MID TO LATE
MORNING BEFORE ANY REMAINING FOG DISSIPATES BY MID DAY.
RODRIGUEZ
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION.
* HIGH CONFIDENCE WITH FOG/VIS TRENDS IN THE NEAR TERM.
* MEDIUM HIGH CONFIDENCE WITH FOG/VIS TRENDS OVERNIGHT...AS WELL
WITH TIMING OF LOWEST VIS TONIGHT.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...GUSTY SOUTHERLY WINDS AND CHANCE OF SHRA...OTHERWISE
VFR.
FRIDAY...MVFR POSSIBLY EARLY...GUSTY NW WINDS...OTHERWISE VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...SLIGHT CHANCE SHRA...OTHERWISE VFR.
RODRIGUEZ
&&
.MARINE...
228 PM CST
A VERY WEAK GRADIENT IS IN PLACE ACROSS THE WESTERN GREAT LAKES
REGION THIS AFTERNOON RESULTING IN LIGHT AND VARIABLE WINDS ACROSS
LAKE MICHIGAN. AREAS OF FOG ARE EXPECTED ACROSS PORTIONS OF THE LAKE
TONIGHT INTO EARLY WEDNESDAY. WINDS SHOULD GRADUALLY MOVE TOWARDS A
SOUTHERLY DIRECTION OVERNIGHT AS LOW PRESSURE MOVES ACROSS THE
CANADIAN PRAIRIES AND OVER HUDSON BAY. THE GRADIENT TIGHTENS
PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE WHERE WINDS WILL
INCREASE TO AROUND 30 KT BY WEDNESDAY EVENING. WEDNESDAY NIGHT INTO
THURSDAY...ANOTHER AREA OF LOW PRESSURE DEVELOPS OVER THE NORTHERN
PLAINS AND MOVES EAST TOWARDS LAKE SUPERIOR BY THURSDAY EVENING.
WINDS IN ADVANCE OF THIS SYSTEM WILL CONTINUE AROUND 30 KT THROUGH
THE DAY THURSDAY. AFTER A COLD FRONT SWEEPS ACROSS THE LAKE THURSDAY
NIGHT...STRONG COLD ADVECTION WILL ALLOW NORTHWEST WINDS TO INCREASE
TO GALES OF 35 TO 40 KT FRIDAY. RIDGING SHOULD MOVE ACROSS THE LAKE
EARLY IN THE WEEKEND ALLOWING WINDS TO DIMINISH...BUT BEYOND
SATURDAY...MODELS CONTINUE TO HAVE SIGNIFICANT DIFFERENCES LEADING
TO VERY LOW CONFIDENCE IN THE FORECAST LATE THIS WEEKEND INTO EARLY
NEXT WEEK. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ019-ILZ020-ILZ021-ILZ032 UNTIL 10 AM
WEDNESDAY.
DENSE FOG ADVISORY...ILZ013-ILZ014-ILZ022-ILZ023-ILZ033-ILZ039
UNTIL 10 AM WEDNESDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 10
AM WEDNESDAY.
LM...DENSE FOG ADVISORY...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-
LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-
LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 AM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
858 PM CST TUE NOV 20 2012
.DISCUSSION...
628 PM CST
HAVE SPED UP THE START TIME OF THE DENSE FOG IN THE FORECAST...AND
WITH FURTHER INCREASED CONFIDENCE ON THE AREA TO MOST LIKELY BE
IMPACTED...HAVE GONE AHEAD AND ISSUED A DENSE FOG ADVISORY FOR
NORTH CENTRAL ILLINOIS AND FAR WESTERN AND NORTHERN AREAS OF THE
CHICAGO METROPOLITAN AREA. THIS MAY VERY WELL NEED TO BE EXPANDED
IN TWO TO THREE HOURS.
WINDS HAVE BECOME CALM OR LIGHT AND VARIABLE ACROSS THE ENTIRE
AREA EARLY THIS EVENING AS THE RIDGE AXIS HAS EXPANDED INTO
NORTHERN IL. DEW POINTS REMAIN ANOMALOUSLY HIGH WITH MID 40S...AND
TEMPERATURE DROPS AT A HANDFUL OF SITES HAVE BEEN AROUND OR EVEN
HIGHER THAN 10F SINCE 4 PM. THIS HAS RESULTED IN T/TD SPREADS OF
LESS THAN 5F ALREADY ACROSS NORTH CENTRAL IL. IN ADDITION..THE
AREAS OF FOG THAT PERSISTED THROUGH TODAY IN EASTERN IA/FAR
SOUTHWEST WI THAT WERE MENTIONED IN THE PRIOR DISCUSSION HAVE ONLY
BLOSSOMED SINCE SUNDOWN. VISIBILITY OBSERVATIONS IN THESE AREAS
ARE ALMOST ALL AT ONE QUARTER MILE OR LESS. SO WITH THE RIDGE AXIS
ONLY FURTHER TRANSITIONING OVER THE AREA THROUGH LATE
EVENING...WOULD EXPECT VISIBILITY TO DROP AND ESPECIALLY RAPID IN
THOSE AREAS WHERE THE PERSISTING FOG EXPANDS IN /WESTERN WINNEBAGO
AND OGLE COUNTIES BY 830 PM/. THE HRRR FORECAST VISIBILITY AGREES
WITH THIS IDEA OF EASTWARD EXPANSION THROUGH LATE EVENING AND
OVERNIGHT.
AS FOR AREAS TO THE EAST...INCLUDING MUCH OF
CHICAGOLAND...WIDESPREAD 3-6 SM VISIBILITIES EXIST. THESE
VISIBILITIES AND WEBCAMS HAVE INDICATED VERY GRADUAL VISIBILITY
REDUCTION SINCE SUNDOWN. LINGERING CLOUDS AND ASSOCIATED MOIST
LAYER AROUND 3K FT ARE LIKELY IMPAIRING FULL RADIATIONAL COOLING
SOMEWHAT...BUT DO FULLY EXPECT THESE AREAS TO COOL MORE QUICKLY
AND DENSE FOG AT LEAST IN PLACES TO DEVELOP. AREAS NEAR THE LAKE
MAY ACTUALLY BECOME MORE FAVORED TO SEE THE FOG MORE QUICKLY DUE
TO A LIGHT BUT MOIST ONSHORE COMPONENT.
IMPROVEMENT IN THE FOG ON WEDNESDAY MORNING MAY BE EXTREMELY
SLOW...WITH SOME AREAS OF FOG LASTING INTO THE EARLY AFTERNOON
GIVEN WHAT OCCURRED UPSTREAM IN EASTERN IOWA TODAY AND JUST THE
CLIMATOLOGY OF THIS TIME OF YEAR. WILL FURTHER ASSESS THIS WITH
00Z GUIDANCE.
MTF
//PREV DISCUSSION...
256 PM CST
TONIGHT THROUGH WEDNESDAY...
GREATEST CONCERN FOR TONIGHT RESIDES WITH THE EXPECTED DEVELOPMENT
OF FOG...TRANSITIONING INTO AREAS OF DENSE FOG OVERNIGHT. THE
OTHER CONCERN IS THAT ONE OF THE BUSIEST TRAVEL DAYS OF THE YEAR
WILL HAVE A SLOW START GIVEN THE EXPECTED DEVELOPMENT OF FOG.
LOOKING UPSTREAM ACROSS EASTERN IOWA FOG HAS LINGERED INTO THIS
AFTERNOON...WITH A FEW LOCATIONS STILL SEEING VSBYS DOWN AROUND 1 TO
2 MILES. THIS AFTN HAS SEEN ALMOST NO MIXING WITH LGT WINDS
GENERALLY LESS THAN 5 MPH...AND DEW POINTS HOLDING UP IN THE MID 40S
FOR MANY LOCATIONS OF NORTHERN IL/NORTHWEST IN. HIGH PRESSURE WILL
REMAIN OVERHEAD TONIGHT...WHICH WILL AID IN DECENT RADIATIONAL
COOLING SHORTLY AFTER SUNSET. THIS ALL POINTS TOWARDS A REPEAT NIGHT
OF AREAS OF FOG AND POTENTIALLY AREAS OF DENSE FOG. OVERNIGHT LOWS
WILL COOL INTO THE LOW 40S...WITH THE EXCEPTION OF AREAS ADJACENT TO
LAKE MICHIGAN WHERE TEMPS MAY HOLD IN THE MID 40S.
ONCE THE FOG DOES DEVELOP IT WILL MOST LIKELY LINGER INTO WED
MORNING...POSSIBLY THROUGH MIDDAY. GIVEN THE SCENARIO OF WHAT HAS
TRANSPIRED ACROSS EASTERN IOWA...COULD SEE THE DENSE FOG LIFT BY
MID-MORNING THEN PATCHY FOG THROUGH NOON. THIS WILL RESULT IN
TEMPERATURES BEING SLOW TO WARM...THUS HAVE SLOWED THE RATE OF CLIMB
UNTIL MIDDAY. THROUGHOUT THE MORNING HOURS TEMPS WILL REMAIN IN THE
LOW/MID 40S...THEN BY MIDDAY AND IMPROVING VSBYS OR BURNING OFF
FOG...TEMPS WILL BEGIN TO CLIMB RAPIDLY INTO THE UPR 50S AND
POSSIBLY 60 DEG IN A FEW LOCATIONS. OTHERWISE SKIES WILL BECOME
MOSTLY CLEAR IN THE AFTERNOON HOURS.
CONFIDENCE...HIGH.
CONFIDENCE ON AREAS OF DENSE FOG...MEDIUM/HIGH.
THANKSGIVING...
500MB RIDGE REMAINS OVERHEAD...WITH A POTENT THERMAL RIDGE AT 850MB
OF 10 TO 12 DEG C. A FEW ENSEMBLE MEMBERS SUGGEST THAT 850MB TEMPS
COULD BE SLIGHTLY WARMER TO 14 DEG C. THE BETTER PRESSURE GRADIENT
REMAINS DISPLACED TO THE NORTHWEST OF THE REGION...WHICH IS THE AREA
THAT WILL SEE THE STRONGEST WARM AIR ADVECTION. EITHER WAY...IT
APPEARS THANKSGIVING WILL END UP BEING A RATHER WARM DAY WITH TEMPS
LIKELY TO REACH THE LOW 60S. PLUMES CONTINUE TO INDICATE A HIGH
CONFIDENCE THAT TEMPS WILL EASILY PUSH TO 60 DEGREES BY NOON. THE
LARGEST CAVEAT COULD BE THAT INCREASED MOISTURE APPEARS TO BE
PROGGED TO POOL ALONG THE BOUNDARY INTO THE MID-MISSISSIPPI
VALLEY...WHICH COULD PUSH CLOUDS OVERHEAD BY LATE MORNING. THIS
MAINLY WILL AFFECT THE WESTERN HALF OF THE CWFA. IN ADDITION HAVE
OVERSPREAD A SLIGHT CHC OF PRECIP BY MIDDAY ALONG AND NORTH OF A LA
SALLE TO CRYSTAL LAKE LINE. THEN ADDITIONAL MOISTURE CONTINUES TO
POUR INTO THE CWFA BY MID-AFTERNOON/EVENING...SO HAVE MAINTAINED
MENTION OF SLT CHC OF RA.
CONFIDENCE IN TEMPS...HIGH.
CONFIDENCE IN PRECIP...LOW.
FRIDAY THROUGH MONDAY...
ENSEMBLES THROUGH THE EXTENDED PERIODS CONTINUE TO SHOW MINIMAL
SPREAD IN ENVELOPE OF SOLUTIONS...LEADING TO THE INCREASED
CONFIDENCE THAT A PATTERN CHANGE IS UPON US. FRIDAY WILL KICK OFF
THE EXTENDED WITH A TASTE OF COLDER AIR...HOWEVER WHAT APPEARS TO BE
TAKING SHAPE FOR MID/LATE NEXT WEEK WILL BE MUCH MORE SIGNIFICANT AS
THE CALENDAR APPROACHES THE FIRST OF DECEMBER.
GUIDANCE CONTINUES TO PROG FRONTAL PASSAGE FOR THE FIRST HALF OF
FRI...POSSIBLY PRIOR TO DAYBREAK. VERY TIGHT PRESSURE GRADIENT IS
ALSO POISED TO ARRIVE BEHIND THE FRONTAL PASSAGE FRI...RESULTING IN
BREEZY CONDITIONS. WITH COOLER AIR STEADILY ADVECTING IN FROM THE
NORTHWEST AS A RESULT OF AN 850MB THERMAL TROUGH OF -10 TO -14 DEG
C...MAX TEMPS FRI COULD BE ACHIEVED PRIOR TO MID-MORNING. THEN IT
APPEARS FALLING TEMPS WILL OCCUR EARLY IN THE AFTERNOON. AT THIS
TIME IT APPEARS A DRY WEDGE WILL OCCUR FRI...SHIFTING ANY MOISTURE
EAST OF THE CWFA. THEN THE TRANSITION TOWARDS LAKE EFFECT PRECIP
DEVELOPS FRI AFTERNOON THROUGH SATURDAY EVENING...WHICH FORTUNATELY
WITH A STRONG WEST/NORTHWEST FLOW THIS PRECIP WILL BE DISPLACED
DOWNSTREAM ACROSS LOWER MICHIGAN AND PERHAPS PORTIONS OF NORTHWEST
INDIANA.
SAT/SUN WILL SEE ANTI-CYCLONIC FLOW PUSH BACK OVERHEAD WITH DRY
WEATHER EXPECTED THROUGH THE WEEKEND INTO EARLY MON. 500MB TROUGH
PIVOTS EAST WITH A RELATIVELY FLAT OR SEMI-ZONAL FLOW SUN/MON. SAT
HIGH TEMPS WILL STRUGGLE TO WARM INTO THE MID/UPR 30S. SUN/MON WILL
BEGIN TO WARM MARGINALLY INTO THE LOW 40S. THIS ALL APPEARS TO BE
TEMPORARY AS THE DEVELOPMENT OF A BLOCKING PATTERN BEGINS TO TAKE
SHAPE OVER ALASKA AND THE NORTH ATLANTIC...WHICH WILL ULTIMATELY
ALLOW MUCH COLDER AIR TO ARRIVE INTO CENTRAL CANADA MID/LATE NEXT
WEEK FROM SIBERIA.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* LIGHT AND VARIABLE WINDS TONIGHT...BECOMING SOUTH/SOUTHWEST
WEDNESDAY.
* IFR FOG/VIS LIKELY IN THE NEAR TERM...WITH LIFR FOG/VIS LIKELY
OVERNIGHT THROUGH WEDNESDAY MORNING.
RODRIGUEZ
//DISCUSSION...UPDATED 00Z...
MAIN CONCERN THIS FORECAST PERIOD IS IN THE NEAR TERM AND
OVERNIGHT WITH FOG/LOW VIS TO AFFECT ALL OF THE TERMINALS. AS
CLOUD COVER CONTINUES TO EXIT THE AREA...COOLER CONDITIONS IN A
RATHER MOIST ENVIRONMENT AND LIGHT WINDS ARE HELPING FOG TO
QUICKLY DEVELOP EARLY THIS EVENING. THERE IS CURRENTLY VIS OF
3-5SM ACROSS MOST OF THE TERMINALS WITH MDW CURRENTLY SHOWING VIS
OF AROUND 2SM. EXPECT THIS 3-5SM TO BE THE PREVAILING CONDITIONS
OVER THE NEXT COUPLE OF HOURS BEFORE CONDITIONS CONTINUE TO
DETERIORATE TONIGHT. VIS OF 1-2SM WILL THEN BE EXPECTED BEFORE AN
EXPANDING AREA OF MORE DENSE FOG...CURRENTLY ACROSS WESTERN
ILLINOIS...EXPANDS FURTHER TO THE EAST. THIS EXPANDING FOG WILL
THEN LIKELY BRING VIS OF LESS THAN 1SM...WITH THESE CONDITIONS
EXPECTED TO REMAIN THROUGH THE MORNING HOURS ON WEDNESDAY.
CONFIDENCE IS GROWING OF THIS LOWER VIS BUT WITH SOME UNCERTAINTY
REMAINING AS TO THE OVERALL TIMING...AS I HAVE CONTINUED TO PUSH
UP THE TIMING OF THE MORE DENSE FOG WITH LATEST TRENDS.
UNCERTAINTY ALSO REMAINS AS TO THE OVERALL DURATION INTO WEDNESDAY
MORNING...BUT WITH SOME IMPROVEMENT EXPECTED BY MID TO LATE
MORNING BEFORE ANY REMAINING FOG DISSIPATES BY MID DAY.
RODRIGUEZ
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION.
* HIGH CONFIDENCE WITH FOG/VIS TRENDS IN THE NEAR TERM.
* MEDIUM HIGH CONFIDENCE WITH FOG/VIS TRENDS OVERNIGHT...AS WELL
WITH TIMING OF LOWEST VIS TONIGHT.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...GUSTY SOUTHERLY WINDS AND CHANCE OF SHRA...OTHERWISE
VFR.
FRIDAY...MVFR POSSIBLY EARLY...GUSTY NW WINDS...OTHERWISE VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...SLIGHT CHANCE SHRA...OTHERWISE VFR.
RODRIGUEZ
&&
.MARINE...
228 PM CST
A VERY WEAK GRADIENT IS IN PLACE ACROSS THE WESTERN GREAT LAKES
REGION THIS AFTERNOON RESULTING IN LIGHT AND VARIABLE WINDS ACROSS
LAKE MICHIGAN. AREAS OF FOG ARE EXPECTED ACROSS PORTIONS OF THE LAKE
TONIGHT INTO EARLY WEDNESDAY. WINDS SHOULD GRADUALLY MOVE TOWARDS A
SOUTHERLY DIRECTION OVERNIGHT AS LOW PRESSURE MOVES ACROSS THE
CANADIAN PRAIRIES AND OVER HUDSON BAY. THE GRADIENT TIGHTENS
PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE WHERE WINDS WILL
INCREASE TO AROUND 30 KT BY WEDNESDAY EVENING. WEDNESDAY NIGHT INTO
THURSDAY...ANOTHER AREA OF LOW PRESSURE DEVELOPS OVER THE NORTHERN
PLAINS AND MOVES EAST TOWARDS LAKE SUPERIOR BY THURSDAY EVENING.
WINDS IN ADVANCE OF THIS SYSTEM WILL CONTINUE AROUND 30 KT THROUGH
THE DAY THURSDAY. AFTER A COLD FRONT SWEEPS ACROSS THE LAKE THURSDAY
NIGHT...STRONG COLD ADVECTION WILL ALLOW NORTHWEST WINDS TO INCREASE
TO GALES OF 35 TO 40 KT FRIDAY. RIDGING SHOULD MOVE ACROSS THE LAKE
EARLY IN THE WEEKEND ALLOWING WINDS TO DIMINISH...BUT BEYOND
SATURDAY...MODELS CONTINUE TO HAVE SIGNIFICANT DIFFERENCES LEADING
TO VERY LOW CONFIDENCE IN THE FORECAST LATE THIS WEEKEND INTO EARLY
NEXT WEEK. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ019-ILZ020-ILZ021-ILZ032 UNTIL 10 AM
WEDNESDAY.
DENSE FOG ADVISORY...ILZ013-ILZ014-ILZ022-ILZ023-ILZ033-ILZ039
UNTIL 10 AM WEDNESDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 10
AM WEDNESDAY.
LM...DENSE FOG ADVISORY...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-
LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-
LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 AM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
629 PM CST TUE NOV 20 2012
.DISCUSSION...
628 PM CST
HAVE SPED UP THE START TIME OF THE DENSE FOG IN THE FORECAST...AND
WITH FURTHER INCREASED CONFIDENCE ON THE AREA TO MOST LIKELY BE
IMPACTED...HAVE GONE AHEAD AND ISSUED A DENSE FOG ADVISORY FOR
NORTH CENTRAL ILLINOIS AND FAR WESTERN AND NORTHERN AREAS OF THE
CHICAGO METROPOLITAN AREA. THIS MAY VERY WELL NEED TO BE EXPANDED
IN TWO TO THREE HOURS.
WINDS HAVE BECOME CALM OR LIGHT AND VARIABLE ACROSS THE ENTIRE
AREA EARLY THIS EVENING AS THE RIDGE AXIS HAS EXPANDED INTO
NORTHERN IL. DEW POINTS REMAIN ANOMALOUSLY HIGH WITH MID 40S...AND
TEMPERATURE DROPS AT A HANDFUL OF SITES HAVE BEEN AROUND OR EVEN
HIGHER THAN 10F SINCE 4 PM. THIS HAS RESULTED IN T/TD SPREADS OF
LESS THAN 5F ALREADY ACROSS NORTH CENTRAL IL. IN ADDITION..THE
AREAS OF FOG THAT PERSISTED THROUGH TODAY IN EASTERN IA/FAR
SOUTHWEST WI THAT WERE MENTIONED IN THE PRIOR DISCUSSION HAVE ONLY
BLOSSOMED SINCE SUNDOWN. VISIBILITY OBSERVATIONS IN THESE AREAS
ARE ALMOST ALL AT ONE QUARTER MILE OR LESS. SO WITH THE RIDGE AXIS
ONLY FURTHER TRANSITIONING OVER THE AREA THROUGH LATE
EVENING...WOULD EXPECT VISIBILITY TO DROP AND ESPECIALLY RAPID IN
THOSE AREAS WHERE THE PERSISTING FOG EXPANDS IN /WESTERN WINNEBAGO
AND OGLE COUNTIES BY 830 PM/. THE HRRR FORECAST VISIBILITY AGREES
WITH THIS IDEA OF EASTWARD EXPANSION THROUGH LATE EVENING AND
OVERNIGHT.
AS FOR AREAS TO THE EAST...INCLUDING MUCH OF
CHICAGOLAND...WIDESPREAD 3-6 SM VISIBILITIES EXIST. THESE
VISIBILITIES AND WEBCAMS HAVE INDICATED VERY GRADUAL VISIBILITY
REDUCTION SINCE SUNDOWN. LINGERING CLOUDS AND ASSOCIATED MOIST
LAYER AROUND 3K FT ARE LIKELY IMPAIRING FULL RADIATIONAL COOLING
SOMEWHAT...BUT DO FULLY EXPECT THESE AREAS TO COOL MORE QUICKLY
AND DENSE FOG AT LEAST IN PLACES TO DEVELOP. AREAS NEAR THE LAKE
MAY ACTUALLY BECOME MORE FAVORED TO SEE THE FOG MORE QUICKLY DUE
TO A LIGHT BUT MOIST ONSHORE COMPONENT.
IMPROVEMENT IN THE FOG ON WEDNESDAY MORNING MAY BE EXTREMELY
SLOW...WITH SOME AREAS OF FOG LASTING INTO THE EARLY AFTERNOON
GIVEN WHAT OCCURRED UPSTREAM IN EASTERN IOWA TODAY AND JUST THE
CLIMATOLOGY OF THIS TIME OF YEAR. WILL FURTHER ASSESS THIS WITH
00Z GUIDANCE.
MTF
&&
.PREV DISCUSSION...
256 PM CST
TONIGHT THROUGH WEDNESDAY...
GREATEST CONCERN FOR TONIGHT RESIDES WITH THE EXPECTED DEVELOPMENT
OF FOG...TRANSITIONING INTO AREAS OF DENSE FOG OVERNIGHT. THE
OTHER CONCERN IS THAT ONE OF THE BUSIEST TRAVEL DAYS OF THE YEAR
WILL HAVE A SLOW START GIVEN THE EXPECTED DEVELOPMENT OF FOG.
LOOKING UPSTREAM ACROSS EASTERN IOWA FOG HAS LINGERED INTO THIS
AFTERNOON...WITH A FEW LOCATIONS STILL SEEING VSBYS DOWN AROUND 1 TO
2 MILES. THIS AFTN HAS SEEN ALMOST NO MIXING WITH LGT WINDS
GENERALLY LESS THAN 5 MPH...AND DEW POINTS HOLDING UP IN THE MID 40S
FOR MANY LOCATIONS OF NORTHERN IL/NORTHWEST IN. HIGH PRESSURE WILL
REMAIN OVERHEAD TONIGHT...WHICH WILL AID IN DECENT RADIATIONAL
COOLING SHORTLY AFTER SUNSET. THIS ALL POINTS TOWARDS A REPEAT NIGHT
OF AREAS OF FOG AND POTENTIALLY AREAS OF DENSE FOG. OVERNIGHT LOWS
WILL COOL INTO THE LOW 40S...WITH THE EXCEPTION OF AREAS ADJACENT TO
LAKE MICHIGAN WHERE TEMPS MAY HOLD IN THE MID 40S.
ONCE THE FOG DOES DEVELOP IT WILL MOST LIKELY LINGER INTO WED
MORNING...POSSIBLY THROUGH MIDDAY. GIVEN THE SCENARIO OF WHAT HAS
TRANSPIRED ACROSS EASTERN IOWA...COULD SEE THE DENSE FOG LIFT BY
MID-MORNING THEN PATCHY FOG THROUGH NOON. THIS WILL RESULT IN
TEMPERATURES BEING SLOW TO WARM...THUS HAVE SLOWED THE RATE OF CLIMB
UNTIL MIDDAY. THROUGHOUT THE MORNING HOURS TEMPS WILL REMAIN IN THE
LOW/MID 40S...THEN BY MIDDAY AND IMPROVING VSBYS OR BURNING OFF
FOG...TEMPS WILL BEGIN TO CLIMB RAPIDLY INTO THE UPR 50S AND
POSSIBLY 60 DEG IN A FEW LOCATIONS. OTHERWISE SKIES WILL BECOME
MOSTLY CLEAR IN THE AFTERNOON HOURS.
CONFIDENCE...HIGH.
CONFIDENCE ON AREAS OF DENSE FOG...MEDIUM/HIGH.
THANKSGIVING...
500MB RIDGE REMAINS OVERHEAD...WITH A POTENT THERMAL RIDGE AT 850MB
OF 10 TO 12 DEG C. A FEW ENSEMBLE MEMBERS SUGGEST THAT 850MB TEMPS
COULD BE SLIGHTLY WARMER TO 14 DEG C. THE BETTER PRESSURE GRADIENT
REMAINS DISPLACED TO THE NORTHWEST OF THE REGION...WHICH IS THE AREA
THAT WILL SEE THE STRONGEST WARM AIR ADVECTION. EITHER WAY...IT
APPEARS THANKSGIVING WILL END UP BEING A RATHER WARM DAY WITH TEMPS
LIKELY TO REACH THE LOW 60S. PLUMES CONTINUE TO INDICATE A HIGH
CONFIDENCE THAT TEMPS WILL EASILY PUSH TO 60 DEGREES BY NOON. THE
LARGEST CAVEAT COULD BE THAT INCREASED MOISTURE APPEARS TO BE
PROGGED TO POOL ALONG THE BOUNDARY INTO THE MID-MISSISSIPPI
VALLEY...WHICH COULD PUSH CLOUDS OVERHEAD BY LATE MORNING. THIS
MAINLY WILL AFFECT THE WESTERN HALF OF THE CWFA. IN ADDITION HAVE
OVERSPREAD A SLIGHT CHC OF PRECIP BY MIDDAY ALONG AND NORTH OF A LA
SALLE TO CRYSTAL LAKE LINE. THEN ADDITIONAL MOISTURE CONTINUES TO
POUR INTO THE CWFA BY MID-AFTERNOON/EVENING...SO HAVE MAINTAINED
MENTION OF SLT CHC OF RA.
CONFIDENCE IN TEMPS...HIGH.
CONFIDENCE IN PRECIP...LOW.
FRIDAY THROUGH MONDAY...
ENSEMBLES THROUGH THE EXTENDED PERIODS CONTINUE TO SHOW MINIMAL
SPREAD IN ENVELOPE OF SOLUTIONS...LEADING TO THE INCREASED
CONFIDENCE THAT A PATTERN CHANGE IS UPON US. FRIDAY WILL KICK OFF
THE EXTENDED WITH A TASTE OF COLDER AIR...HOWEVER WHAT APPEARS TO BE
TAKING SHAPE FOR MID/LATE NEXT WEEK WILL BE MUCH MORE SIGNIFICANT AS
THE CALENDAR APPROACHES THE FIRST OF DECEMBER.
GUIDANCE CONTINUES TO PROG FRONTAL PASSAGE FOR THE FIRST HALF OF
FRI...POSSIBLY PRIOR TO DAYBREAK. VERY TIGHT PRESSURE GRADIENT IS
ALSO POISED TO ARRIVE BEHIND THE FRONTAL PASSAGE FRI...RESULTING IN
BREEZY CONDITIONS. WITH COOLER AIR STEADILY ADVECTING IN FROM THE
NORTHWEST AS A RESULT OF AN 850MB THERMAL TROUGH OF -10 TO -14 DEG
C...MAX TEMPS FRI COULD BE ACHIEVED PRIOR TO MID-MORNING. THEN IT
APPEARS FALLING TEMPS WILL OCCUR EARLY IN THE AFTERNOON. AT THIS
TIME IT APPEARS A DRY WEDGE WILL OCCUR FRI...SHIFTING ANY MOISTURE
EAST OF THE CWFA. THEN THE TRANSITION TOWARDS LAKE EFFECT PRECIP
DEVELOPS FRI AFTERNOON THROUGH SATURDAY EVENING...WHICH FORTUNATELY
WITH A STRONG WEST/NORTHWEST FLOW THIS PRECIP WILL BE DISPLACED
DOWNSTREAM ACROSS LOWER MICHIGAN AND PERHAPS PORTIONS OF NORTHWEST
INDIANA.
SAT/SUN WILL SEE ANTI-CYCLONIC FLOW PUSH BACK OVERHEAD WITH DRY
WEATHER EXPECTED THROUGH THE WEEKEND INTO EARLY MON. 500MB TROUGH
PIVOTS EAST WITH A RELATIVELY FLAT OR SEMI-ZONAL FLOW SUN/MON. SAT
HIGH TEMPS WILL STRUGGLE TO WARM INTO THE MID/UPR 30S. SUN/MON WILL
BEGIN TO WARM MARGINALLY INTO THE LOW 40S. THIS ALL APPEARS TO BE
TEMPORARY AS THE DEVELOPMENT OF A BLOCKING PATTERN BEGINS TO TAKE
SHAPE OVER ALASKA AND THE NORTH ATLANTIC...WHICH WILL ULTIMATELY
ALLOW MUCH COLDER AIR TO ARRIVE INTO CENTRAL CANADA MID/LATE NEXT
WEEK FROM SIBERIA.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* LIGHT AND VARIABLE WINDS TONIGHT...BECOMING SOUTH/SOUTHWEST
WEDNESDAY.
* MVFR FOG LIKELY IN THE NEAR TERM...WITH IFR AND LIFR FOG
BECOMING LIKELY LATER THIS EVENING AND OVERNIGHT.
RODRIGUEZ
//DISCUSSION...UPDATED 00Z...
MAIN CONCERN THIS FORECAST PERIOD IS IN THE NEAR TERM AND
OVERNIGHT WITH FOG/LOW VIS TO AFFECT ALL OF THE TERMINALS. AS
CLOUD COVER CONTINUES TO EXIT THE AREA...COOLER CONDITIONS IN A
RATHER MOIST ENVIRONMENT AND LIGHT WINDS ARE HELPING FOG TO
QUICKLY DEVELOP EARLY THIS EVENING. THERE IS CURRENTLY VIS OF
3-5SM ACROSS MOST OF THE TERMINALS WITH MDW CURRENTLY SHOWING VIS
OF AROUND 2SM. EXPECT THIS 3-5SM TO BE THE PREVAILING CONDITIONS
OVER THE NEXT COUPLE OF HOURS BEFORE CONDITIONS CONTINUE TO
DETERIORATE TONIGHT. VIS OF 1-2SM WILL THEN BE EXPECTED BEFORE AN
EXPANDING AREA OF MORE DENSE FOG...CURRENTLY ACROSS WESTERN
ILLINOIS...EXPANDS FURTHER TO THE EAST. THIS EXPANDING FOG WILL
THEN LIKELY BRING VIS OF LESS THAN 1SM...WITH THESE CONDITIONS
EXPECTED TO REMAIN THROUGH THE MORNING HOURS ON WEDNESDAY.
CONFIDENCE IS GROWING OF THIS LOWER VIS BUT WITH SOME UNCERTAINTY
REMAINING AS TO THE OVERALL TIMING...AS I HAVE CONTINUED TO PUSH
UP THE TIMING OF THE MORE DENSE FOG WITH LATEST TRENDS.
UNCERTAINTY ALSO REMAINS AS TO THE OVERALL DURATION INTO WEDNESDAY
MORNING...BUT WITH SOME IMPROVEMENT EXPECTED BY MID TO LATE
MORNING BEFORE ANY REMAINING FOG DISSIPATES BY MID DAY.
RODRIGUEZ
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION.
* HIGH CONFIDENCE WITH FOG/VIS TRENDS IN THE NEAR TERM WITH MEDIUM
CONFIDENCE WITH FOG/VIS TRENDS LATER THIS EVENING AND
OVERNIGHT...AND WITH LOW MEDIUM CONFIDENCE OF EXACT TIMING OF
LOWEST VIS TONIGHT.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...GUSTY SOUTHERLY WINDS AND CHANCE OF SHRA...OTHERWISE
VFR.
FRIDAY...MVFR POSSIBLY EARLY...GUSTY NW WINDS...OTHERWISE VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...SLIGHT CHANCE SHRA...OTHERWISE VFR.
RODRIGUEZ
&&
.MARINE...
228 PM CST
A VERY WEAK GRADIENT IS IN PLACE ACROSS THE WESTERN GREAT LAKES
REGION THIS AFTERNOON RESULTING IN LIGHT AND VARIABLE WINDS ACROSS
LAKE MICHIGAN. AREAS OF FOG ARE EXPECTED ACROSS PORTIONS OF THE LAKE
TONIGHT INTO EARLY WEDNESDAY. WINDS SHOULD GRADUALLY MOVE TOWARDS A
SOUTHERLY DIRECTION OVERNIGHT AS LOW PRESSURE MOVES ACROSS THE
CANADIAN PRAIRIES AND OVER HUDSON BAY. THE GRADIENT TIGHTENS
PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE WHERE WINDS WILL
INCREASE TO AROUND 30 KT BY WEDNESDAY EVENING. WEDNESDAY NIGHT INTO
THURSDAY...ANOTHER AREA OF LOW PRESSURE DEVELOPS OVER THE NORTHERN
PLAINS AND MOVES EAST TOWARDS LAKE SUPERIOR BY THURSDAY EVENING.
WINDS IN ADVANCE OF THIS SYSTEM WILL CONTINUE AROUND 30 KT THROUGH
THE DAY THURSDAY. AFTER A COLD FRONT SWEEPS ACROSS THE LAKE THURSDAY
NIGHT...STRONG COLD ADVECTION WILL ALLOW NORTHWEST WINDS TO INCREASE
TO GALES OF 35 TO 40 KT FRIDAY. RIDGING SHOULD MOVE ACROSS THE LAKE
EARLY IN THE WEEKEND ALLOWING WINDS TO DIMINISH...BUT BEYOND
SATURDAY...MODELS CONTINUE TO HAVE SIGNIFICANT DIFFERENCES LEADING
TO VERY LOW CONFIDENCE IN THE FORECAST LATE THIS WEEKEND INTO EARLY
NEXT WEEK. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ019-ILZ020-ILZ021-ILZ032 UNTIL 10 AM
WEDNESDAY.
IN...NONE.
LM...DENSE FOG ADVISORY...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-
LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-
LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 AM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
605 PM CST TUE NOV 20 2012
.DISCUSSION...
ISSUED 605 PM CST TUE NOV 20 2012
CLOUDS WILL CONTINUE TO SLOWLY CLEAR FROM NORTHWEST TO SOUTHEAST
THIS EVENING...WITH MOSTLY CLEAR SKIES EXPECTED ACROSS THE
BOARD AFTER MIDNIGHT. WITH CLEAR SKIES AND NEARLY CALM WINDS
BENEATH A SURFACE RIDGE AXIS...EXCELLENT RADIATIONAL COOLING
CONDITIONS WILL ALLOW SURFACE-BASED SATURATION TO OCCUR OVERNIGHT.
00Z/6PM IR SATELLITE IMAGERY SHOWS A PERSISTENT AREA OF DENSE FOG
ALONG THE MISSISSIPPI RIVER BEGINNING TO SLOWLY SPREAD EASTWARD.
20Z HRRR HAS AN EXCELLENT HANDLE ON THE FOG AREA...AND SHOWS IT
EXPANDING FURTHER EASTWARD INTO THE ILLINOIS RIVER VALLEY BETWEEN
03Z/9PM AND 06Z/12AM...THEN FURTHER EAST TO THE I-55 CORRIDOR
AFTER MIDNIGHT. HAVE THEREFORE ISSUED A DENSE FOG ADVISORY FOR ALL
LOCATIONS ALONG AND WEST OF A BLOOMINGTON-NORMAL TO TAYLORVILLE
LINE TONIGHT INTO WEDNESDAY MORNING. AM EXPECTING VISBYS TO DROP
TO LESS THAN 1/4 MILE AT TIMES...IMPACTING THE EARLY MORNING
COMMUTE. FURTHER EAST...FORECAST SOUNDINGS SHOW SLIGHTLY DRIER AIR
AT LOW-LEVELS...SUGGESTING FOG WITH VISBYS GENERALLY IN THE 1 TO 3
MILE RANGE TOWARD DAWN. UPDATED ZONE FORECAST HAS ALREADY BEEN
ISSUED.
BARNES
&&
.AVIATION...
ISSUED 542 PM CST TUE NOV 20 2012
MAIN AVIATION CONCERN WITH THE 00Z TAFS WILL BE THE POTENTIAL FOR
DENSE FOG TONIGHT. CURRENT VISBYS AT THE CENTRAL ILLINOIS
TERMINALS ARE UNRESTRICTED...HOWEVER A PERSISTENT AREA OF DENSE
FOG ALONG THE MISSISSIPPI RIVER IS BEGINNING TO SLOWLY EXPAND
EASTWARD. FORECAST SOUNDINGS SUGGEST THE COLUMN IS A BIT DRIER
THAN LAST NIGHT...HOWEVER WITH CLEARING SKIES AND NEARLY CALM
WINDS BENEATH SURFACE HIGH PRESSURE...RADIATIONAL COOLING WILL
LEAD TO SURFACE-BASED SATURATION. 20Z HRRR HAS AN EXCELLENT HANDLE
ON THE CURRENT FOG AREA...AND IT SHOWS THE FOG EXPANDING EASTWARD
INTO THE ILLINOIS RIVER VALLEY BETWEEN 03Z AND 06Z...THEN FURTHER
EAST TO THE I-55 CORRIDOR OVERNIGHT. HAVE REDUCED VISBYS TO 1/4SM
AT ALL TERMINALS EXCEPT KCMI BETWEEN 09Z AND 14Z. SLIGHTLY DRIER
LOW-LEVEL ENVIRONMENT WILL LIKELY PREVENT DENSE FOG FURTHER
EAST...SO HAVE ONLY TAKEN VISBYS DOWN TO 1SM AT KCMI. ONCE THE FOG
DISSIPATES...MOSTLY CLEAR SKIES AND LIGHT WINDS WILL PREVAIL
AFTER 15Z WED.
BARNES
&&
.PREV DISCUSSION...
ISSUED 307 PM CST TUE NOV 20 2012
MAIN CONCERNS THIS FORECAST PACKAGE INVOLVE PCPN CHANCES FOR
THURSDAY AND THURSDAY NIGHT WITH MILD TEMPS...AND CHC PCPN FOR
MONDAY THROUGH TUESDAY...ALONG WITH COOLER TEMPS THROUGH THE
EXTENDED PERIOD. MODELS REMAIN RELATIVELY SIMILAR IN THE SHORT
TERM BUT DIFFER SLIGHTLY WITH THE TIMING AND INTENSITY OF THE
SHORT WAVE COMING THROUGH THE AREA THUR AND THUR NIGHT...ALONG
WITH AMOUNT OF PCPN EXPECTED WITH THE FRONT. BELIEVE A BLEND OF
THE MODELS LOOKS BEST IN THE SHORT TERM. MODELS IN THE EXTENDED
PERIOD ALSO LOOK SIMILAR WITH DIFFERENCES BETWEEN THE ECMWF AND
THE GFS BEING WITH THE LOCATION AND STRENGTH OF A SFC LOW MOVING
NORTHEAST OUT OF THE SOUTHERN PLAINS EARLY NEXT WEEK.
SHORT TERM...TONIGHT THROUGH FRIDAY
HIGH PRSS WILL DRIFT ACROSS THE AREA TONIGHT...BRINGING VERY LIGHT
WINDS. DEWPOINTS HAVE INCREASED DURING THE DAY AND WITH AN
INVERSION EXPECTED TO SETUP THIS EVENING...DENSE FOG SEEMS
POSSIBLE. HOWEVER...MOST OF CWA HAS HAD LOTS OF SUNSHINE THIS
AFTERNOON AND BELIEVE THE SUN HAS BEEN ABLE TO BURN OFF SOME OF
THE LOW LEVEL MOISTURE. MODELS DIFFER ON WHAT RESULTING DEWPOINTS
WILL BE IN THE MORNING AS TEMPS FALL. BECAUSE OF SUNSHINE THIS
AFTERNOON AM NOT CONVINCED THAT DENSE FOG WILL OCCUR...BUT DO
THINK THERE WILL BE FOG OVERNIGHT. SO WILL HAVE AREAS OF FOG IN
THE FORECAST FOR OVERNIGHT AND MORNING HOURS TILL ABOUT 15Z. COULD
BE SOME ISOLATED/LOCALIZED AREAS WHERE FOG BECOMES DENSE...BUT NOT
ASSURED ENOUGH TO ADD TO FORECAST. WILL LET EVENING SHIFT EVALUATE.
AS HIGH PRSS MOVES TO THE SOUTHEAST TOMORROW...AM EXPECTING DRY
AND WARM WEATHER TOMORROW AND THURSDAY. THEN A FRONT WILL MOVE
INTO THE AREA LATE THURSDAY AND INTO THURSDAY NIGHT. BELIEVE
MOISTURE WILL STILL BE LIMITED BUT ENOUGH THAT PCPN CHANCES WILL
HAVE TO BE INCREASED FOR THURSDAY NIGHT. NAM IS DRY THROUGH THE
PERIOD...WHILE GFS HAS LOTS OF PCPN. SO WILL LIMITED POPS TO JUST
UNDER LIKELY GIVEN DIFFERENCES AND LIMIT MOISTURE EXPECTED. CLOUDS
AND PCPN MAY LINGER IN SOUTHEAST FRIDAY SO HAVE INCLUDED SLIGHT
CHC IN SOUTHEAST FOR FRI...MAINLY IN THE MORNING.
TEMPS WILL REMAIN ABOVE NORMAL FOR TWO MORE DAY AHEAD OF THE FRONT
BUT THEN FALL BEHIND THE FRONT. TEMPS FRIDAY EXPECTED TO BE IN THE
40S WITH AROUND 50 IN THE SOUTHEAST. THESE TEMPS WILL BE SLIGHTLY
BELOW NORMAL.
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY
COOLER HIGH PRSS WILL BUILD INTO THE REGION FOR THE WEEKEND AND
TEMPS WILL BE COOLER THAN NORMAL THROUGH THE EXTENDED PERIOD.
ANOTHER FRONTAL SYSTEM WILL MOVE INTO THE AREA FOR BEGINNING OF
NEXT WEEK BUT MODELS DIFFER ON TIMING/POSITION/STRENGTH OF THE
FRONT/SYSTEM. HOWEVER...MODELS DO HAVE SOME PCPN FORECAST FOR MON
THROUGH TUE. SO REAL QUESTION WOULD BE PRECIP TYPE THROUGH THAT
TIME FRAME. BASED ON TRACK OF THE LOW PRSS AREA...MOST PCPN SHOULD
REMAIN ACROSS THE SOUTHERN TWO THIRDS OF THE CWA. WITH TEMPS
FALLING TO BELOW FREEZING AT NIGHT...WILL HAVE PCPN TYPE OF
RAIN OR SNOW AND THEN ALL SNOW OVER PARTS OF THE AREA. THIS COULD
CHANGE IF FURTHER NORTH TRACK FROM ECMWF FORECAST HOLDS TRUE
THROUGH REST OF THE WEEK. LOTS OF TIME TO WATCH AND SEE.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM CST WEDNESDAY FOR ILZ027>031-
036>038-040>043-047>053.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
542 PM CST TUE NOV 20 2012
.DISCUSSION...
ISSUED 307 PM CST TUE NOV 20 2012
MAIN CONCERNS THIS FORECAST PACKAGE INVOLVE PCPN CHANCES FOR
THURSDAY AND THURSDAY NIGHT WITH MILD TEMPS...AND CHC PCPN FOR
MONDAY THROUGH TUESDAY...ALONG WITH COOLER TEMPS THROUGH THE
EXTENDED PERIOD. MODELS REMAIN RELATIVELY SIMILAR IN THE SHORT
TERM BUT DIFFER SLIGHTLY WITH THE TIMING AND INTENSITY OF THE
SHORT WAVE COMING THROUGH THE AREA THUR AND THUR NIGHT...ALONG
WITH AMOUNT OF PCPN EXPECTED WITH THE FRONT. BELIEVE A BLEND OF
THE MODELS LOOKS BEST IN THE SHORT TERM. MODELS IN THE EXTENDED
PERIOD ALSO LOOK SIMILAR WITH DIFFERENCES BETWEEN THE ECMWF AND
THE GFS BEING WITH THE LOCATION AND STRENGTH OF A SFC LOW MOVING
NORTHEAST OUT OF THE SOUTHERN PLAINS EARLY NEXT WEEK.
SHORT TERM...TONIGHT THROUGH FRIDAY
HIGH PRSS WILL DRIFT ACROSS THE AREA TONIGHT...BRINGING VERY LIGHT
WINDS. DEWPOINTS HAVE INCREASED DURING THE DAY AND WITH AN
INVERSION EXPECTED TO SETUP THIS EVENING...DENSE FOG SEEMS
POSSIBLE. HOWEVER...MOST OF CWA HAS HAD LOTS OF SUNSHINE THIS
AFTERNOON AND BELIEVE THE SUN HAS BEEN ABLE TO BURN OFF SOME OF
THE LOW LEVEL MOISTURE. MODELS DIFFER ON WHAT RESULTING DEWPOINTS
WILL BE IN THE MORNING AS TEMPS FALL. BECAUSE OF SUNSHINE THIS
AFTERNOON AM NOT CONVINCED THAT DENSE FOG WILL OCCUR...BUT DO
THINK THERE WILL BE FOG OVERNIGHT. SO WILL HAVE AREAS OF FOG IN
THE FORECAST FOR OVERNIGHT AND MORNING HOURS TILL ABOUT 15Z. COULD
BE SOME ISOLATED/LOCALIZED AREAS WHERE FOG BECOMES DENSE...BUT NOT
ASSURED ENOUGH TO ADD TO FORECAST. WILL LET EVENING SHIFT EVALUATE.
AS HIGH PRSS MOVES TO THE SOUTHEAST TOMORROW...AM EXPECTING DRY
AND WARM WEATHER TOMORROW AND THURSDAY. THEN A FRONT WILL MOVE
INTO THE AREA LATE THURSDAY AND INTO THURSDAY NIGHT. BELIEVE
MOISTURE WILL STILL BE LIMITED BUT ENOUGH THAT PCPN CHANCES WILL
HAVE TO BE INCREASED FOR THURSDAY NIGHT. NAM IS DRY THROUGH THE
PERIOD...WHILE GFS HAS LOTS OF PCPN. SO WILL LIMITED POPS TO JUST
UNDER LIKELY GIVEN DIFFERENCES AND LIMIT MOISTURE EXPECTED. CLOUDS
AND PCPN MAY LINGER IN SOUTHEAST FRIDAY SO HAVE INCLUDED SLIGHT
CHC IN SOUTHEAST FOR FRI...MAINLY IN THE MORNING.
TEMPS WILL REMAIN ABOVE NORMAL FOR TWO MORE DAY AHEAD OF THE FRONT
BUT THEN FALL BEHIND THE FRONT. TEMPS FRIDAY EXPECTED TO BE IN THE
40S WITH AROUND 50 IN THE SOUTHEAST. THESE TEMPS WILL BE SLIGHTLY
BELOW NORMAL.
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY
COOLER HIGH PRSS WILL BUILD INTO THE REGION FOR THE WEEKEND AND
TEMPS WILL BE COOLER THAN NORMAL THROUGH THE EXTENDED PERIOD.
ANOTHER FRONTAL SYSTEM WILL MOVE INTO THE AREA FOR BEGINNING OF
NEXT WEEK BUT MODELS DIFFER ON TIMING/POSITION/STRENGTH OF THE
FRONT/SYSTEM. HOWEVER...MODELS DO HAVE SOME PCPN FORECAST FOR MON
THROUGH TUE. SO REAL QUESTION WOULD BE PRECIP TYPE THROUGH THAT
TIME FRAME. BASED ON TRACK OF THE LOW PRSS AREA...MOST PCPN SHOULD
REMAIN ACROSS THE SOUTHERN TWO THIRDS OF THE CWA. WITH TEMPS
FALLING TO BELOW FREEZING AT NIGHT...WILL HAVE PCPN TYPE OF
RAIN OR SNOW AND THEN ALL SNOW OVER PARTS OF THE AREA. THIS COULD
CHANGE IF FURTHER NORTH TRACK FROM ECMWF FORECAST HOLDS TRUE
THROUGH REST OF THE WEEK. LOTS OF TIME TO WATCH AND SEE.
&&
.AVIATION...
ISSUED 542 PM CST TUE NOV 20 2012
MAIN AVIATION CONCERN WITH THE 00Z TAFS WILL BE THE POTENTIAL FOR
DENSE FOG TONIGHT. CURRENT VISBYS AT THE CENTRAL ILLINOIS
TERMINALS ARE UNRESTRICTED...HOWEVER A PERSISTENT AREA OF DENSE
FOG ALONG THE MISSISSIPPI RIVER IS BEGINNING TO SLOWLY EXPAND
EASTWARD. FORECAST SOUNDINGS SUGGEST THE COLUMN IS A BIT DRIER
THAN LAST NIGHT...HOWEVER WITH CLEARING SKIES AND NEARLY CALM
WINDS BENEATH SURFACE HIGH PRESSURE...RADIATIONAL COOLING WILL
LEAD TO SURFACE-BASED SATURATION. 20Z HRRR HAS AN EXCELLENT HANDLE
ON THE CURRENT FOG AREA...AND IT SHOWS THE FOG EXPANDING EASTWARD
INTO THE ILLINOIS RIVER VALLEY BETWEEN 03Z AND 06Z...THEN FURTHER
EAST TO THE I-55 CORRIDOR OVERNIGHT. HAVE REDUCED VISBYS TO 1/4SM
AT ALL TERMINALS EXCEPT KCMI BETWEEN 09Z AND 14Z. SLIGHTLY DRIER
LOW-LEVEL ENVIRONMENT WILL LIKELY PREVENT DENSE FOG FURTHER
EAST...SO HAVE ONLY TAKEN VISBYS DOWN TO 1SM AT KCMI. ONCE THE FOG
DISSIPATES...MOSTLY CLEAR SKIES AND LIGHT WINDS WILL PREVAIL
AFTER 15Z WED.
BARNES
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1034 AM CST MON NOV 19 2012
.DISCUSSION...
ISSUED 1035 AM CST MON NOV 19 2012
UPDATED THE FORECAST TODAY TO INCREASE CHANCES OF SHOWERS OVER THE
IL RIVER VALLEY INTO MIDDAY TO 50% AND ALSO TO INCREASE CLOUD
COVER ACROSS AREA TODAY. GENERALLY A MOSTLY CLOUDY DAY WITH CHANCE
OF SHOWERS WEST OF I-55 INTO EARLY AFTERNOON. HIGHS IN THE UPPER 50S
OVER CENTRAL IL AND AROUND 60F SE OF I-70. SOUTH WINDS 5 TO 15 MPH.
1034 MB HIGH PRESSURE OVER NEW ENGLAND WAS STILL RIDGING SW INTO
THE MID/LOWER MS VALLEY WHILE A COLD FRONT WAS FROM NW MN INTO SE
NEBRASKA. RADAR MOSAIC SHOWS A SMALL BAND OF MAINLY LIGHT RAIN
SHOWERS OVER WESTERN IL INTO EASTERN MO AND FAR SE IA LIFTING NE
TOWARD THE IL RIVER LATE THIS MORNING. THESE LIGHT SHOWERS
ASSOCIATED WITH A WEAK UPPER LEVEL DISTURBANCE EMBEDDED IN AN
UPPER LEVEL TROF OVER THE MIDWEST. THIS FEATURE SHOULD EXIT
CENTRAL/NORTHERN IL DURING THE AFTERNOON WITH LIGHT SHOWERS
DIMINISHING OVER THE IL RIVER VALLEY. TEMPS CURRENTLY RANGE FROM
45 TO 55F AND CLOUDS WILL LIMIT WARMING WITH HIGHS IN THE UPPER
50S CENTRAL IL AND NEAR 60F IN SE IL.
07
&&
.AVIATION...
ISSUED 559 AM CST MON NOV 19 2012
PREDOMINANTLY VFR CONDITIONS EXPECTED ACROSS THE CENTRAL ILLINOIS
TERMINALS THROUGH THE 12Z TAF VALID TIME. HOWEVER...THE GRADUAL
PASSAGE OF AN UPPER LEVEL DISTURBANCE WILL CAUSE CIGS TO
THICKEN/LOWER WITH TIME. SOME OF THE MODEL GUIDANCE SUGGESTS MVFR
CIGS WILL DEVELOP BY LATE TONIGHT...BUT THIS IS NOT A UNANIMOUS
AGREEMENT. SOME VERY LIGHT RAIN/SPRINKLES ARE POSSIBLE AS THE
DISTURBANCE STARTS TO PUSH THROUGH...BUT DO NOT EXPECT MUCH IN THE
WAY OF MEASURABLE RAINFALL AT ANY ONE TERMINAL. FOR NOW...HAVE
LIMITED VCSH MENTION TO KPIA/KSPI WHERE THE POTENTIAL RAINFALL
WILL ARRIVE FIRST...WITH A DRYING TREND EXPECTED AS THE PATCHY
RAIN MOVES FURTHER EAST. SOUTHERLY WIND AOB 10 KTS ARE EXPECTED
FOR MOST OF THE PERIOD...BUT THE PASSAGE OF A SURFACE TROF LATER
TONIGHT WILL HAVE WINDS SHIFTING TO THE NORTHWEST.
BAK
&&
.PREV DISCUSSION...
ISSUED 256 AM CST MON NOV 19 2012
OVERALL...NOT A LOT OF CHANGES IN THE FORECAST. MAIN ISSUES ARE
TWO PERIODS OF POTENTIAL PRECIP...AND UNSEASONABLY WARM
TEMPERATURES. PREDOMINANTLY ZONAL FLOW THROUGH THE FORECAST...WITH
A COUPLE OF WAVES ALTERING THE FLOW BRIEFLY. UPPER LOW MOVING JUST
OFF THE SERN ATLANTIC COAST...AND ANOTHER WAVE PUSHING SOME
SHOWERS OVER THE MISSISSIPPI RIVER VALLEY. FIRST ISSUE WILL BE THE
PROGRESSION OF THE SHOWERS INTO ILLINOIS TODAY. OTHER THAN
THAT...WARM TEMPS THROUGH THE FIRST HALF OF THE WEEK PUSHING THE
MAXES OVER GUIDANCE. NOT A LOT OF DISSENSION BETWEEN THE
MODELS...JUST WITH THE MOS. PUSHING FORECAST MORE TOWARDS RAW
SOLUTIONS AS A RESULT. NEXT SHOT AT SHOWERY PRECIP ON TRACK FOR
THANKSGIVING DAY.
SHORT TERM...TODAY AND TONIGHT...
SHOWERS MOVING INTO THE MISS RIVER VALLEY THIS MORNING. A BIT OF
CONFLICT IN HIGH RES MODELS AS TO WHETHER OR NOT IT WILL MAKE IT
INTO CENTRAL IL. HRRR SAYS YES...WITH A SECOND ROUND APPROACHING
FROM THE SW FOR A SECONDARY ENHANCEMENT MID MORNING. 4KM WRF IS A
BIT MORE CONSERVATIVE...NAM AND ECMWF ARE DRY. AS A RESULT...AND
AT LEAST TO COVER FOR SPRINKLES THROUGH THE MORNING WITH
REMNANTS...SLIGHT POPS DOMINATE THE WESTERN THIRD OF THE CWA. WILL
HAVE TO MONITOR CLOSELY...BUT SO FAR THE SOLUTION SEEMS PLENTY AS
THE COVERAGE OF THE SHOWERS IS REDUCING ON RADAR. SHORT LIVED
PRECIP NOT ENOUGH TO COUNTER THE WARM UP THAT CONTINUES TODAY AS
SOUTHERLY WINDS GET A BIT MORE ESTABLISHED THIS AFTERNOON. MILD
TEMPS CONTINUE INTO THE OVERNIGHT YET AGAIN.
LONG TERM...TUESDAY THROUGH SUNDAY...
HIGH PRESSURE RIDGE SLOWLY DRIFTS EASTWARD...OR AT LEAST BECOMES
FAR MORE DIFFUSE FROM THE MIDWEST TO THE SOUTHERN PLAINS...AND
THE CLOSED UPPER LOW KICKS OUT OF THE SE. THE WARMING TREND
CONTINUES THROUGH MID WEEK...BRINGING TEMPS UP A DEGREE OR SO EACH DAY.
850MB TEMPS AT 6-7C WILL HAVE THE POTENTIAL TO TRANSLATE INTO
UPPER 50S/LOWER 60S. GUIDANCE HAS NOT COMPLETELY LATCHED ONTO THE
WARMING TREND...THOUGH THE MODEL FIELDS CLEARLY SHOW THE THERMAL
RIDGE IN THE WESTERN CONUS DEEPENING AND SLOWLY CREEPING INTO THE
MIDWEST. HAVE BUMPED MAX TEMPS A FEW DEGREES AHEAD OF ALLBLEND FOR
MON- WED...AND A BIT ON THURSDAY. THURSDAY MAY BE COMPLICATED BY
AN APPROACHING STORM SYSTEM AND ASSOCIATED CLOUD COVER...BUT
SYSTEM STILL HAS A BIT OF UNCERTAINTY AS FAR AS MID AND LOW LEVEL
MOISTURE FIELDS. ALLBLEND PUSHING POPS TO CHANCE CAT.
HJS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
559 AM CST MON NOV 19 2012
.DISCUSSION...
ISSUED 256 AM CST MON NOV 19 2012
OVERALL...NOT A LOT OF CHANGES IN THE FORECAST. MAIN ISSUES ARE
TWO PERIODS OF POTENTIAL PRECIP...AND UNSEASONABLY WARM
TEMPERATURES. PREDOMINANTLY ZONAL FLOW THROUGH THE FORECAST...WITH
A COUPLE OF WAVES ALTERING THE FLOW BRIEFLY. UPPER LOW MOVING JUST
OFF THE SERN ATLANTIC COAST...AND ANOTHER WAVE PUSHING SOME
SHOWERS OVER THE MISSISSIPPI RIVER VALLEY. FIRST ISSUE WILL BE THE
PROGRESSION OF THE SHOWERS INTO ILLINOIS TODAY. OTHER THAN
THAT...WARM TEMPS THROUGH THE FIRST HALF OF THE WEEK PUSHING THE
MAXES OVER GUIDANCE. NOT A LOT OF DISSENSION BETWEEN THE
MODELS...JUST WITH THE MOS. PUSHING FORECAST MORE TOWARDS RAW
SOLUTIONS AS A RESULT. NEXT SHOT AT SHOWERY PRECIP ON TRACK FOR
THANKSGIVING DAY.
SHORT TERM...TODAY AND TONIGHT...
SHOWERS MOVING INTO THE MISS RIVER VALLEY THIS MORNING. A BIT OF
CONFLICT IN HIGH RES MODELS AS TO WHETHER OR NOT IT WILL MAKE IT
INTO CENTRAL IL. HRRR SAYS YES...WITH A SECOND ROUND APPROACHING
FROM THE SW FOR A SECONDARY ENHANCEMENT MID MORNING. 4KM WRF IS A
BIT MORE CONSERVATIVE...NAM AND ECMWF ARE DRY. AS A RESULT...AND
AT LEAST TO COVER FOR SPRINKLES THROUGH THE MORNING WITH
REMNANTS...SLIGHT POPS DOMINATE THE WESTERN THIRD OF THE CWA. WILL
HAVE TO MONITOR CLOSELY...BUT SO FAR THE SOLUTION SEEMS PLENTY AS
THE COVERAGE OF THE SHOWERS IS REDUCING ON RADAR. SHORT LIVED
PRECIP NOT ENOUGH TO COUNTER THE WARM UP THAT CONTINUES TODAY AS
SOUTHERLY WINDS GET A BIT MORE ESTABLISHED THIS AFTERNOON. MILD
TEMPS CONTINUE INTO THE OVERNIGHT YET AGAIN.
LONG TERM...TUESDAY THROUGH SUNDAY...
HIGH PRESSURE RIDGE SLOWLY DRIFTS EASTWARD...OR AT LEAST BECOMES
FAR MORE DIFFUSE FROM THE MIDWEST TO THE SOUTHERN PLAINS...AND
THE CLOSED UPPER LOW KICKS OUT OF THE SE. THE WARMING TREND
CONTINUES THROUGH MID WEEK...BRINGING TEMPS UP A DEGREE OR SO EACH DAY.
850MB TEMPS AT 6-7C WILL HAVE THE POTENTIAL TO TRANSLATE INTO
UPPER 50S/LOWER 60S. GUIDANCE HAS NOT COMPLETELY LATCHED ONTO THE
WARMING TREND...THOUGH THE MODEL FIELDS CLEARLY SHOW THE THERMAL
RIDGE IN THE WESTERN CONUS DEEPENING AND SLOWLY CREEPING INTO THE
MIDWEST. HAVE BUMPED MAX TEMPS A FEW DEGREES AHEAD OF ALLBLEND FOR
MON- WED...AND A BIT ON THURSDAY. THURSDAY MAY BE COMPLICATED BY
AN APPROACHING STORM SYSTEM AND ASSOCIATED CLOUD COVER...BUT
SYSTEM STILL HAS A BIT OF UNCERTAINTY AS FAR AS MID AND LOW LEVEL
MOISTURE FIELDS. ALLBLEND PUSHING POPS TO CHANCE CAT.
HJS
&&
.AVIATION...
ISSUED 559 AM CST MON NOV 19 2012
PREDOMINANTLY VFR CONDITIONS EXPECTED ACROSS THE CENTRAL ILLINOIS
TERMINALS THROUGH THE 12Z TAF VALID TIME. HOWEVER...THE GRADUAL
PASSAGE OF AN UPPER LEVEL DISTURBANCE WILL CAUSE CIGS TO
THICKEN/LOWER WITH TIME. SOME OF THE MODEL GUIDANCE SUGGESTS MVFR
CIGS WILL DEVELOP BY LATE TONIGHT...BUT THIS IS NOT A UNANIMOUS
AGREEMENT. SOME VERY LIGHT RAIN/SPRINKLES ARE POSSIBLE AS THE
DISTURBANCE STARTS TO PUSH THROUGH...BUT DO NOT EXPECT MUCH IN THE
WAY OF MEASURABLE RAINFALL AT ANY ONE TERMINAL. FOR NOW...HAVE
LIMITED VCSH MENTION TO KPIA/KSPI WHERE THE POTENTIAL RAINFALL
WILL ARRIVE FIRST...WITH A DRYING TREND EXPECTED AS THE PATCHY
RAIN MOVES FURTHER EAST. SOUTHERLY WIND AOB 10 KTS ARE EXPECTED
FOR MOST OF THE PERIOD...BUT THE PASSAGE OF A SURFACE TROF LATER
TONIGHT WILL HAVE WINDS SHIFTING TO THE NORTHWEST.
BAK
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
327 AM CST MON NOV 19 2012
.DISCUSSION...
ISSUED 256 AM CST MON NOV 19 2012
OVERALL...NOT A LOT OF CHANGES IN THE FORECAST. MAIN ISSUES ARE
TWO PERIODS OF POTENTIAL PRECIP...AND UNSEASONABLY WARM
TEMPERATURES. PREDOMINANTLY ZONAL FLOW THROUGH THE FORECAST...WITH
A COUPLE OF WAVES ALTERING THE FLOW BRIEFLY. UPPER LOW MOVING JUST
OFF THE SERN ATLANTIC COAST...AND ANOTHER WAVE PUSHING SOME
SHOWERS OVER THE MISSISSIPPI RIVER VALLEY. FIRST ISSUE WILL BE THE
PROGRESSION OF THE SHOWERS INTO ILLINOIS TODAY. OTHER THAN
THAT...WARM TEMPS THROUGH THE FIRST HALF OF THE WEEK PUSHING THE
MAXES OVER GUIDANCE. NOT A LOT OF DISSENSION BETWEEN THE
MODELS...JUST WITH THE MOS. PUSHING FORECAST MORE TOWARDS RAW
SOLUTIONS AS A RESULT. NEXT SHOT AT SHOWERY PRECIP ON TRACK FOR
THANKSGIVING DAY.
SHORT TERM...TODAY AND TONIGHT...
SHOWERS MOVING INTO THE MISS RIVER VALLEY THIS MORNING. A BIT OF
CONFLICT IN HIGH RES MODELS AS TO WHETHER OR NOT IT WILL MAKE IT
INTO CENTRAL IL. HRRR SAYS YES...WITH A SECOND ROUND APPROACHING
FROM THE SW FOR A SECONDARY ENHANCEMENT MID MORNING. 4KM WRF IS A
BIT MORE CONSERVATIVE...NAM AND ECMWF ARE DRY. AS A RESULT...AND
AT LEAST TO COVER FOR SPRINKLES THROUGH THE MORNING WITH
REMNANTS...SLIGHT POPS DOMINATE THE WESTERN THIRD OF THE CWA. WILL
HAVE TO MONITOR CLOSELY...BUT SO FAR THE SOLUTION SEEMS PLENTY AS
THE COVERAGE OF THE SHOWERS IS REDUCING ON RADAR. SHORT LIVED
PRECIP NOT ENOUGH TO COUNTER THE WARM UP THAT CONTINUES TODAY AS
SOUTHERLY WINDS GET A BIT MORE ESTABLISHED THIS AFTERNOON. MILD
TEMPS CONTINUE INTO THE OVERNIGHT YET AGAIN.
LONG TERM...TUESDAY THROUGH SUNDAY...
HIGH PRESSURE RIDGE SLOWLY DRIFTS EASTWARD...OR AT LEAST BECOMES
FAR MORE DIFFUSE FROM THE MIDWEST TO THE SOUTHERN PLAINS...AND
THE CLOSED UPPER LOW KICKS OUT OF THE SE. THE WARMING TREND
CONTINUES THROUGH MID WEEK...BRINGING TEMPS UP A DEGREE OR SO EACH DAY.
850MB TEMPS AT 6-7C WILL HAVE THE POTENTIAL TO TRANSLATE INTO
UPPER 50S/LOWER 60S. GUIDANCE HAS NOT COMPLETELY LATCHED ONTO THE
WARMING TREND...THOUGH THE MODEL FIELDS CLEARLY SHOW THE THERMAL
RIDGE IN THE WESTERN CONUS DEEPENING AND SLOWLY CREEPING INTO THE
MIDWEST. HAVE BUMPED MAX TEMPS A FEW DEGREES AHEAD OF ALLBLEND FOR
MON- WED...AND A BIT ON THURSDAY. THURSDAY MAY BE COMPLICATED BY
AN APPROACHING STORM SYSTEM AND ASSOCIATED CLOUD COVER...BUT
SYSTEM STILL HAS A BIT OF UNCERTAINTY AS FAR AS MID AND LOW LEVEL
MOISTURE FIELDS. ALLBLEND PUSHING POPS TO CHANCE CAT.
HJS
&&
.AVIATION...
ISSUED 1143 PM CST SUN NOV 18 2012...FOR THE 06Z TAFS
VFR CONDITIONS ARE EXPECTED OVER THE NEXT 24 HOURS...WITH CLOUD
HEIGHTS GRADUALLY LOWERING WITH TIME BUT REMAINING ABOVE 3K FT
THROUGH 06Z TOMORROW NIGHT. AN UPPER LEVEL SHORTWAVE ARRIVING
LATER MONDAY AFTERNOON AND MON EVE WILL COINCIDE WITH INCREASING
LOWER LEVEL MOISTURE. HOWEVER...LITTLE IN THE WAY OF PRECIP IS
EXPECTED AS MID AND UPPER LEVEL MOISTURE DEPART EASTWARD AT THAT
SAME TIME. SPRINKLES MAY DEVELOP LATER MON AFTN/MON EVE...BUT
CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE A MENTION OF RAIN AT THIS
POINT.
WINDS WILL BE LIGHT SOUTHEAST THE REST OF THE NIGHT...THEN
INCREASE TO 10-13KT OUT OF THE SOUTH ON MONDAY...IN RESPONSE TO
A TIGHTENING PRESSURE GRADIENT.
NO REDUCTIONS TO VISIBILITY ARE EXPECTED OVER THE NEXT 24 HOURS.
SHIMON
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
741 PM CST TUE NOV 20 2012
.UPDATE...
VIS/FOG SATELLITE IMAGERY SHOWS LOW STRATUS AND FOG HAS ENTERED
FORECAST AREA FROM THE EAST WITH OBS INDICATING VISIBILITIES QUICKLY
DROPPING TO NEAR ZERO ONCE IT BEGINS. HAVE ONLY INCLUDED TWO TIERS
OF ERN COUNTIES FOR A START EXPECTING WESTWARD PROGRESSION TO
EVENTAULLY CEASE WHERE IT ENCOUNTERS DRIER AIRMASS. LATEST RAP
1000-950MB RH DROPS QUICKLY TO AROUND 50 PERCENT ALONG THE I35
CORRIDOR.
&&
.SHORT TERM /TONIGHT/...
SFC HIGH CENTERED FROM SRN IA SOUTHWESTWARD TO SLIDE EAST SOUTHEAST
TONIGHT...WITH SOUTHERLY FLOW AND WAA KICKING IN ALOFT. MOSTLY CLEAR
SKIES EXPECTED TONIGHT WITH THE EXCEPTION OF THE FAR EAST...WHERE
LOW STRATUS/FOG THAT IS CURRENTLY ACROSS SOUTHEASTERN IOWA EXPECTED
TO BUILD BACK WEST/NORTHWARD THIS EVENING. THEREFORE LOW CLOUDS/FOG
POSSIBLE FROM WATERLOO TO MARSHALLTOWN TO OTTUMWA OVERNIGHT...BASED
ON THE HRRR OUTPUT FOR LOW CLOUDS. AS SFC RIDGE AXIS PUSHES THROUGH
THE AREA AND WAA/SOUTHERLY FLOW INCREASES EXPECT MIN TEMPS TO START
LEVELING OFF/POSSIBLY WARMING TOWARD SUNRISE.
.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL SHIFT OFF TO THE SOUTHEAST ON WEDNESDAY AS A
BROAD AREA OF HIGH PRESSURE MOVES INTO THE DAKOTAS. THIS WILL
INCREASE THE SOUTHERLY FLOW INTO IOWA AS THE THERMAL RIDGE LEANS
INTO THE STATE. THESE CONDITIONS ALONG WITH VERY DRY AIR WILL BE
CONDUCIVE TO GOOD WARMING. AN INVERSION NEAR 900 MB APPEARS TO BE A
LIMITING FACTOR FROM ACHIEVING RECORD HIGH TEMPERATURES IN THE LOWER
70S HOWEVER EVEN IF THE INVERSION HOLDS...SUPER ADIABATIC LAPSE NEAR
SURFACE SHOULD PUSH READINGS INTO THE MID TO UPPER 60S. THE THERMAL
RIDGE STRENGTHENS WEDNESDAY NIGHT WITH SOUTHERLY WINDS CONTINUING.
LOWS WILL BE WELL INTO THE 40S AT MOST LOCATIONS. THURSDAY WILL HAVE
A WARM START WITH A COLD FRONT EXPECTED TO PASS THROUGH CENTRAL IOWA
DURING THE AFTERNOON. AN SHORT WAVE WILL LIFT UP THROUGH THE
SOUTHWEST FLOW AHEAD OF THE BOUNDARY AND WILL BRING THE CHANCE FOR A
FEW SHOWERS OVER THE FAR SOUTHEAST. THE NMM AND ARW BASED MODELS ARE
FARTHER SOUTHEAST WITH THIS SYSTEM THOUGH THE ECMWF AND GFS AFFECT
IOWA MORE. GENERALLY ANY PRECIPITATION WILL BE LIGHT. THIS SYSTEM
COULD BRING AN INCREASE IN CLOUDS AND MAY LIMIT TEMPERATURES A BIT.
CENTRAL AND SOUTHEAST IOWA SHOULD REACH THE 60S BEFORE THE COLD
FRONT PASSES THROUGH. STRONGER COLD ADVECTION NEAR 850 MB WILL
ENHANCE MIXING BEHIND THE FRONTAL BOUNDARY WITH INCREASING
SUBSIDENCE AIDING MOMENTUM TRANSFER OF WINDS TO THE SURFACE. MIXED
LAYER WINDS OF 25 TO 35 KTS SHOULD PUSH SUSTAINED WINDS TO NEAR WIND
ADVISORY CRITERIA MAINLY OVER THE NORTH AND WEST.
ANOTHER SURGE OF COLD ADVECTION WILL DROP SOUTH THURSDAY NIGHT.
FRIDAY WILL BE BLUSTERY AND COLD WITH BREEZY NORTHWEST WINDS. HIGHS
WILL GENERALLY BE IN THE LOW TO MID 30S. HIGH PRESSURE MOVES ACROSS
FRIDAY NIGHT. CURRENTLY HAVE LOWS A FEW DEGREES ABOVE MOS GUIDANCE
FOR POTENTIAL MID TO HIGH LEVEL CLOUDS WITH INCREASING THETA-E
ADVECTION THROUGH THOSE LEVELS. MINOR MODERATION SATURDAY INTO
SUNDAY. A STRONGER COLD FRONT IS DUE TO ARRIVE MONDAY AND LEAD TO A
COLD START TO NEXT WEEK. THE EXTENDED WILL BE MOSTLY DRY WITH THE
POTENTIAL FOR VERY LIGHT RAIN OR SNOW EARLY NEXT WEEK.
&&
.AVIATION...21/00Z
ALTHOUGH TAF SITES ARE CURRENTLY MOSTLY CLEAR/VFR...LIFR CONDITIONS
ARE PRESENTLY OVER MUCH OF ERN IA AT 2330Z AND ARE EXPECTED TO
ADVANCE WESTWARD INTO KALO AND KOTM THIS EVENING. 20Z HRRR IS
DEPICTING REALITY QUITE WELL AND DEVELOPS LOW STRATUS AND FOG INTO
THESE LOCATIONS AROUND 02Z-03Z AND PERSISTING INTO EARLY WED
MORNING. KEPT IT OUT OF KMCW FOR THE TIME BEING WITH A CURRENT
TEMP/DEWPOINT SPREAD OF 13F...BUT TRENDS WILL HAVE TO BE WATCHED.
CONDITIONS WILL LIKELY EITHER BE VFR OR LIFR WITH LITTLE IN
BETWEEN. REGARDLESS EXPECT VFR RETURNING TO ALL SITES BY 15-16Z WED
AS SLY WINDS CONTINUE TO GRADUALLY INCREASE WITH MIXING.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY UNTIL 900 AM
BUTLER-BREMER-GRUNDY-BLACK HAWK-MARSHALL-TAMA-JASPER-POWESHIEK-
MARION-MAHASKA-MONROE-WAPELLO-APPANOOSE-DAVIS
&&
$$
SHORT TERM...MJB
LONG TERM...DONAVON
AVIATION...SMALL
AREA FORECAST DISCUSSION
NWS DES MOINES IA
536 PM CST TUE NOV 20 2012
.SHORT TERM /TONIGHT/...
SFC HIGH CENTERED FROM SRN IA SOUTHWESTWARD TO SLIDE EAST SOUTHEAST
TONIGHT...WITH SOUTHERLY FLOW AND WAA KICKING IN ALOFT. MOSTLY CLEAR
SKIES EXPECTED TONIGHT WITH THE EXCEPTION OF THE FAR EAST...WHERE
LOW STRATUS/FOG THAT IS CURRENTLY ACROSS SOUTHEASTERN IOWA EXPECTED
TO BUILD BACK WEST/NORTHWARD THIS EVENING. THEREFORE LOW CLOUDS/FOG
POSSIBLE FROM WATERLOO TO MARSHALLTOWN TO OTTUMWA OVERNIGHT...BASED
ON THE HRRR OUTPUT FOR LOW CLOUDS. AS SFC RIDGE AXIS PUSHES THROUGH
THE AREA AND WAA/SOUTHERLY FLOW INCREASES EXPECT MIN TEMPS TO START
LEVELING OFF/POSSIBLY WARMING TOWARD SUNRISE.
.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL SHIFT OFF TO THE SOUTHEAST ON WEDNESDAY AS A
BROAD AREA OF HIGH PRESSURE MOVES INTO THE DAKOTAS. THIS WILL
INCREASE THE SOUTHERLY FLOW INTO IOWA AS THE THERMAL RIDGE LEANS
INTO THE STATE. THESE CONDITIONS ALONG WITH VERY DRY AIR WILL BE
CONDUCIVE TO GOOD WARMING. AN INVERSION NEAR 900 MB APPEARS TO BE A
LIMITING FACTOR FROM ACHIEVING RECORD HIGH TEMPERATURES IN THE LOWER
70S HOWEVER EVEN IF THE INVERSION HOLDS...SUPER ADIABATIC LAPSE NEAR
SURFACE SHOULD PUSH READINGS INTO THE MID TO UPPER 60S. THE THERMAL
RIDGE STRENGTHENS WEDNESDAY NIGHT WITH SOUTHERLY WINDS CONTINUING.
LOWS WILL BE WELL INTO THE 40S AT MOST LOCATIONS. THURSDAY WILL HAVE
A WARM START WITH A COLD FRONT EXPECTED TO PASS THROUGH CENTRAL IOWA
DURING THE AFTERNOON. AN SHORT WAVE WILL LIFT UP THROUGH THE
SOUTHWEST FLOW AHEAD OF THE BOUNDARY AND WILL BRING THE CHANCE FOR A
FEW SHOWERS OVER THE FAR SOUTHEAST. THE NMM AND ARW BASED MODELS ARE
FARTHER SOUTHEAST WITH THIS SYSTEM THOUGH THE ECMWF AND GFS AFFECT
IOWA MORE. GENERALLY ANY PRECIPITATION WILL BE LIGHT. THIS SYSTEM
COULD BRING AN INCREASE IN CLOUDS AND MAY LIMIT TEMPERATURES A BIT.
CENTRAL AND SOUTHEAST IOWA SHOULD REACH THE 60S BEFORE THE COLD
FRONT PASSES THROUGH. STRONGER COLD ADVECTION NEAR 850 MB WILL
ENHANCE MIXING BEHIND THE FRONTAL BOUNDARY WITH INCREASING
SUBSIDENCE AIDING MOMENTUM TRANSFER OF WINDS TO THE SURFACE. MIXED
LAYER WINDS OF 25 TO 35 KTS SHOULD PUSH SUSTAINED WINDS TO NEAR WIND
ADVISORY CRITERIA MAINLY OVER THE NORTH AND WEST.
ANOTHER SURGE OF COLD ADVECTION WILL DROP SOUTH THURSDAY NIGHT.
FRIDAY WILL BE BLUSTERY AND COLD WITH BREEZY NORTHWEST WINDS. HIGHS
WILL GENERALLY BE IN THE LOW TO MID 30S. HIGH PRESSURE MOVES ACROSS
FRIDAY NIGHT. CURRENTLY HAVE LOWS A FEW DEGREES ABOVE MOS GUIDANCE
FOR POTENTIAL MID TO HIGH LEVEL CLOUDS WITH INCREASING THETA-E
ADVECTION THROUGH THOSE LEVELS. MINOR MODERATION SATURDAY INTO
SUNDAY. A STRONGER COLD FRONT IS DUE TO ARRIVE MONDAY AND LEAD TO A
COLD START TO NEXT WEEK. THE EXTENDED WILL BE MOSTLY DRY WITH THE
POTENTIAL FOR VERY LIGHT RAIN OR SNOW EARLY NEXT WEEK.
&&
.AVIATION...21/00Z
ALTHOUGH TAF SITES ARE CURRENTLY MOSTLY CLEAR/VFR...LIFR CONDITIONS
ARE PRESENTLY OVER MUCH OF ERN IA AT 2330Z AND ARE EXPECTED TO
ADVANCE WESTWARD INTO KALO AND KOTM THIS EVENING. 20Z HRRR IS
DEPICTING REALITY QUITE WELL AND DEVELOPS LOW STRATUS AND FOG INTO
THESE LOCATIONS AROUND 02Z-03Z AND PERSISTING INTO EARLY WED
MORNING. KEPT IT OUT OF KMCW FOR THE TIME BEING WITH A CURRENT
TEMP/DEWPOINT SPREAD OF 13F...BUT TRENDS WILL HAVE TO BE WATCHED.
CONDITIONS WILL LIKELY EITHER BE VFR OR LIFR WITH LITTLE IN
BETWEEN. REGARDLESS EXPECT VFR RETURNING TO ALL SITES BY 15-16Z WED
AS SLY WINDS CONTINUE TO GRADUALLY INCREASE WITH MIXING.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...MJB
LONG TERM...DONAVON
AVIATION...SMALL
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
315 PM CST MON NOV 19 2012
.SYNOPSIS...
12Z UA ANALYSIS HAS SEVERAL WEAK TROFS FROM THE WESTERN GREAT LAKES
INTO THE ROCKIES. AT 850MB A MOISTURE PLUME EXTENDED FROM THE BAY OF
CAMPECHE UP INTO CENTRAL IOWA. RADAR TRENDS THROUGH EARLY AFTERNOON
SHOW A CONTINUED DECREASE OF THE PRECIPITATION AS THE OVERALL FORCING
WEAKENS. AT THE SAME TIME...LOW CLOUDS HAD DEVELOPED ON THE EASTERN
EDGE OF THE CLEARING AND WERE NOW OVER THE MID MISSISSIPPI VALLEY.
18Z SFC ANALYSIS HAS A VERY WEAK LOW ALONG THE OK/TX BORDER EAST OF
KAMA WITH A TROF EXTENDING NORTH FROM THE LOW INTO NORTHERN
MINNESOTA. A WEAK COLD FRONT RAN FROM NORTHWEST MINNESOTA INTO SOUTH
DAKOTA. DEW POINTS WERE IN THE 40S AND 50S IN A BROAD MOISTURE PLUME
FROM TEXAS INTO IOWA WITH 30S ACROSS THE REMAINDER OF THE MIDWEST
AND PLAINS.
&&
.SHORT TERM...TONIGHT AND TUESDAY...
THE ONLY EXPLANATION FOR THE RAPID DEVELOPMENT OF THE LOW CLOUDS
ACROSS THE CWFA SINCE LATE MORNING IS CONVERGENT FLOW AHEAD OF THE
TROF. THIS CONVERGENCE CONTINUES THIS AFTERNOON SO THE CLOUDS ARE
EXPECTED TO REMAIN ACROSS THE AREA. RADAR TRENDS SUGGEST THE
POTENTIAL FOR SOME SPRINKLES/VERY LIGHT SHRA TO CONTINUE INTO THE
LATE AFTERNOON HOURS AS WELL IN THE EASTERN CWFA.
GOING ON THE ASSUMPTION THAT THE RAP TRENDS ARE CORRECT...THE
OVERALL CONVERGENCE IS PROGGED TO WEAKEN THIS EVENING WHICH SHOULD
ALLOW THE CLOUDS TO PARTIALLY BREAK UP IN THE WESTERN CWFA. IN THE
EASTERN CWFA LINGERING SPRINKLES ARE POSSIBLE EARLY THIS EVENING.
THE RAP TRENDS AFTER MIDNIGHT ARE DISTURBING. THE CONVERGENT FLOW IS
PROGGED TO INCREASE AGAIN AND THE RAP IS INDICATING THAT A WEAK LOW
WILL MOVE ALONG THE TROF INTO THE CWFA PRIOR TO SUNRISE. WITH
PLENTIFUL LOW LEVEL MOISTURE IN PLACE THE CLOUDS ARE EXPECTED TO
RE-DEVELOP OR FOG/STRATUS WILL DEVELOP IN THE CLEAR AREAS. THUS WILL
ADD AREAS OF FOG IN THE WESTERN CWFA AND PATCHY FOG EAST WHERE THE
CLOUDS ARE EXPECTED TO LINGER LONGER.
I CANNOT RULE OUT THE POSSIBILITY OF A HEADLINE FOR THE FOG LATE
TONIGHT INTO TUESDAY MORNING. HOW THE CLOUDS AND POTENTIAL FOG
DEVELOP/EVOLVE LATE TONIGHT WILL BE THE KEY. IF ONE HAD TO ASSIGN A
PROBABILITY IT IS CURRENTLY 1 IN 5 OR 1 IN 4 REGARDING A HEADLINE.
ASSUMING THAT LOW CLOUDS/FOG DEVELOP LATE TONIGHT THEY WILL CONTINUE
INTO TUESDAY MORNING. THE FOG SHOULD LIFT BY LATE MORNING WITH THE
CLOUDS EXPECTED TO CLEAR OUT DURING THE AFTERNOON. THE RATE OF
CLEARING ON TUESDAY IS A CONCERN GIVEN THE WEAK SUN. IT IS ENTIRELY
POSSIBLE THAT THE CLOUDS MAY NOT CLEAR OUT UNTIL CLOSE TO SUNSET
TUESDAY. IF THAT OCCURS...THE CURRENT MAX TEMPERATURES FOR TUESDAY
ARE TOO WARM. ..08..
.LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...
TUESDAY NIGHT AND WEDNESDAY...BOTH SFC AND UPPER RIDGING STILL ON
TRACK TO GET PRESSED ACRS THE REGION THIS PERIOD AS WELL AS
UNSEASONABLY MILD TEMPS. LIGHT WINDS AND CLEAR OUT OF CLOUDS WILL
MAKE FOR A COOLER NIGHT TUE NIGHT WITH LOWS WELL DOWN IN THE 30S.
DEPENDING ON TUE AFTERNOON CLOUD CLEAR OUT...THE LATER THE CLEARING
TREND AND THUS REDUCING THE SFC MIX OUT DRYING...TUE NIGHT MAY BE AN
IDEAL RADIATIONAL FOG SET UP ESPECIALLY ALONG AND EAST OF THE MS RVR.
WILL HOLD OFF MENTION FOR NOW BUT FOLLOWING SHIFTS WILL HAVE TO
ASSESS THIS POTENTIAL. AS FOR WED...TEMPORARY OMEGA BLOCK OVER
STRENGTHENING WARMING LLVL RETURN FLOW STILL APPEAR ON TAP. EXTENT OF
AVERAGED LLVL THERMAL DRAW BY THE MAJORITY OF THE NEW 12Z RUN MODELS
AND MIXING UP INTO BASE ON BUILDING WARM WEDGE ALOFT SUPPORTS
WIDESPREAD HIGHS IN THE UPPER 50S IN THE FAR NORTHEAST...TO THE MID
60S IN THE SOUTHWEST. UNSEASONABLY MILD WED NIGHT AND IF SOUTHERLY
SFC WINDS CAN MAINTAIN AT 5-10 KTS...MANY AREAL TEMPS WILL BE HELD UP
FROM DIPPING BELOW THE MID-UPPER 40S. BUT MAY PLAY IT COOLER IN CASE
OF ANY SFC WIND DECREASE EVEN IF TEMPORARY.
THURSDAY AND FRIDAY... INCOMING PACIFIC NW WAVE ENERGY/DEVELOPING
CYCLONE ACRS THE NORTHERN PLAINS AND ASSOCIATED SFC FRONT PROJECTED
BY LATER RUNS TO SWEEP THROUGH THE DVN CWA THU EVENING. ACTUAL FROPA
OCCURRING ACRS THE MS RVR FROM THE WEST PROGGED BY ENSEMBLE MEAN NOW
LOOKS TO OCCUR AROUND OR JUST AFTER 00Z FRI...THUS THE BULK OF THU
THE DVN CWA TO BE IN BREEZY PRE-FRONTAL WARM SECTOR. STOUT INVERSION
ALOFT AND INCREASE IN LOW-TO-MID LEVEL MOISTURE/CLOUDS COULD BE THE
LIMITING FACTOR AND PREVENT A RECORD MILD THANKSGIVING. IF IT WERE
NOT FOR THOSE FACTORS...SOME AREAS WOULD HIT 70 OR HIGHER. BUT
WILL WITH A MORE CONSERVATIVE LOW TO MID 60S. STRENGTH OF LLVL FRONT
ITSELF AND MID-UPPER LOW ROLLING ACRS THE UPPER MS RVR VALLEY SHOULD
BE ENOUGH TO DEVELOP SOME SHOWERS JUST AHEAD OF THE FRONT THU
AFTERNOON AND EVENING EVEN TAKING INTO ACCOUNT SOMEWHAT LIMITED
MOISTURE RETURN INTO THE FROPA PROCESS. BUT IF LATER RUNS TREND
WETTER...SOME MODERATE SHOWERS AN POSSIBLY EVEN A THUNDERSTORM MAY BE
POSSIBLE THU AFTERNOON/EVENING. IT ALL DEPENDS ON ANY BUILD UP OF
INSTABILITY IF IT CAN AS THU PROGRESSES. DEPENDING ON THE FRONTAL
TIMING...LATE NIGHT SWITCH OVER TO LLVL COLD CONVEYOR COULD PLUNGE
MUCH OF THE NORTHWEST HALF OF THE LOCAL FCST AREA INTO THE LOW TO MID
30S. FRIDAY STILL ON TRACK TO BE A MUCH COLDER BLUSTERY DAY IN
SUBSIDING DRY SLOT OFF GRT LKS CYCLONE...WITH HIGHS HAVING TROUBLE
GETTING OUT OF THE UPPER 30S TO LOWER 40S AS NORTHWEST WINDS GUST
OVER 30 MPH. WRAP AROUND SNOW FLURRIES/SHOWERS MAY NOT BE ALL THAT
FAR AWAY FROM THE LOCAL AREA ACRS SOUTHERN WI. IF SFC WINDS DECOUPLE
UNDER CLEAR SKIES FRI NIGHT...LOWS COULD DIP INTO THE LOWER 20S TO
EVEN UPPER TEENS IN SOME LOCATIONS BY EARLY SAT MORNING.
SATURDAY THROUGH NEXT MONDAY...LATEST RUN OF THE MEDIUM RANGE
SOLUTIONS AND ENSEMBLES SUGGEST A QUICK RETURN TO PROGRESSIVE
WESTERLIES/ FLATTENED FLOW PATTERN ACRS MUCH OF THE CONUS...THUS DRY
AND THERMALLY MODERATING WX INTO SUNDAY AND SUNDAY NIGHT. HIGHS BY
SUNDAY BACK INTO THE MID 40S TO NEAR 50 WITH SOME RETURN FLOW MIXING
AND INSOLATION. AS FOR EARLY TO MID NEXT WEEK...NORTHERN HEMISPHERIC
TELECONNECTIONS SUGGEST ENOUGH WAVE ENERGY/UPPER JET INFLUX DIGGING
INTO THE WEST FOR AN EVENTUAL L/W TROF COMPLEX ACRS THE SOUTHWESTERN
ROCKIES AND GRT BSN. MANY COMPLEX PHASING ISSUES TO BE RESOLVED THAT
FAR OUT...BUT THE GENERAL SIGNAL OF A LOADED SOUTHWEST FLOW PATTERN
ACRS THE WESTERN TO MID CONUS WITH COLD AIR TRYING TO DUMP DOWN THE
PLAINS AND UPPER MIDWEST WHILE A WARM MOIST CONVEYOR STREAMS UP
NORTHWARD TO THE LEE OF THE L/W TROF...COULD MAKE FOR A VERY
INTERESTING MID TO LATE WEEK PERIOD. STAY TUNED. ..12..
&&
.AVIATION...
MVFR CIGS ARE EXPECTED TO PERSIST THROUGH 00Z/20 AND POSSIBLY BEYOND
BEFORE LIFTING TO VFR. THE RAP MODEL TRENDS SHOW CONVERGENCE BECOMING
STRONGER AFT 06Z/20 WITH PLENTIFUL MOISTURE IN PLACE. THUS THERE IS
NOW A REAL CONCERN OF IFR/LIFR CONDITIONS DEVELOPING AFT 06Z/20 WITH
THE POTENTIAL FOR VLIFR CONDITIONS. THIS POSSIBILITY IS CURRENTLY NOT
IN THE TAFS THAT WERE ISSUED AT 18Z/19. THE 18Z TAFS WILL BE AMENDED
TO SHOW MVFR CONDITIONS DEVELOPING AFT 06Z/20 WITH POTENTIAL MARGINAL
IFR. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
08/12
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1149 AM CST MON NOV 19 2012
.UPDATE...
BASED ON CURRENT RADAR AND RAP TRENDS THE FCST HAS BEEN ADJUSTED
SLIGHTLY TO REFLECT WHAT IS CURRENTLY HAPPENING. THE BULK OF THE
PRECIPITATION IS EXITING THE CWFA BUT LINGERING SHRA AND POSSIBLE
SPRINKLES REMAIN. MOST OF THIS LINGERING PRECIPITATION SHOULD END
EARLY THIS AFTERNOON.
MORE CLOUDS DEVELOPED MID TO LATE MORNING ACROSS IOWA AT THE START
OF THE CLEARING. THIS CLOUD DEVELOPMENT APPEARS TO BE RELATED TO
SOME INCREASED LIFT AND STEEP MID LEVEL LAPSE RATES. AS SUCH
CLOUDS MAY LINGER A LITTLE LONGER THAN EXPECTED. TEMPERATURES HAVE
BEEN ADJUSTED SOMEWHAT TO REFLECT CLOUDS STICKING AROUND A LITTLE
LONGER THAN PREVIOUSLY THOUGHT. ..08..
&&
.AVIATION...
VFR WX IS EXPECTED THROUGH 06Z/20 AS SHRA DEPART THE AREA. AFT
06Z/20 GUIDANCE IS DEVELOPING IFR/LIFR CONDITIONS. HOWEVER...THE
AMOUNT OF MOISTURE IN THE LOWEST LEVELS OF THE MODELS AT THAT TIME
IS SUSPECT. PRIOR TO SUNRISE TODAY THERE WERE ONLY SPOTTY MVFR/IFR
CONDITIONS IN THE PLAINS. THE 18Z TAFS WERE WRITTEN TO REFLECT
POSSIBLE MVFR CONDITIONS DEVELOPING AFT 06Z/20 WITH 6SM. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
851 AM CST MON NOV 19 2012
.UPDATE...
A QUICK REVIEW OF 12Z UA DATA AND RAP TRENDS INDICATE THE
PRECIPITATION WILL BE SHUTTING DOWN RATHER QUICKLY DURING THE
MORNING HOURS DUE TO DRY AIR AND WEAKENING FORCING.
RAP TRENDS ON THE 305K SFC DEPICT REASONABLY WELL WHAT IS
CURRENTLY GOING ON. THESE TRENDS INDICATE DECREASING PRECIP
CHANCES ACROSS THE NORTHERN CWFA WITH BETTER CHANCES OVER THE
SOUTHEAST HALF DUE TO WEAKER BUT RELATIVELY STRONGER. THE BACK
EDGE OF THE PRECIPITATION SEEMS TO BE REASONABLY TIED TO THE 10MB
CONDENSATION PRESSURE DEFICIT ON THE 305K SFC. USING THIS AND THE
OVERALL FORCING SUGGESTS MOST PRECIPITATION SHOULD END BY MID DAY
WITH PERHAPS A FEW SPRINKLES/ISOLD SHRA IN THE FAR EAST EARLY THIS
AFTERNOON.
CLOUDS WILL CONTINUE TO DECREASE AS WELL DURING THE LATE MORNING
AND AFTERNOON FROM WEST TO EAST. THIS DECREASE WILL LIKELY AFFECT
TEMPERATURES AS WELL WITH THE WESTERN THIRD OF THE CWFA
POTENTIALLY WARMER THAN FCST. ..08..
&&
.PREV DISCUSSION... /ISSUED 541 AM CST MON NOV 19 2012/
UPDATE...
RADAR TRENDS HAVE SHOWN A STEADY WEAKENING OF THE RAIN BAND AS IT
WORKS ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. HAVE
RAISED POPS FOR THE EARLY MORNING HOURS...AS THE AREAS THAT ARE
RAINING ARE ACTUALLY PRODUCING SEVERAL HUNDREDTHS OF RAINFALL.
STILL NOT MUCH...BUT NOTICEABLE. THE BACK EDGE OF THE CLOUD COVER
IS ALSO STEADILY MARCHING EAST. THE TIMING OF THIS IS
CONSIDERABLY FASTER THAN PREVIOUSLY FORECAST...AND HAVE ADJUSTED
SKY COVER IN THE FORECAST TO ACCOUNT FOR AN AFTERNOON CLEARING
TREND. LE
AVIATION...
CURRENT RAIN BAND HAS VFR CIGS AND VSBYS...AND WILL GRADUALLY WORK
ACROSS THE TERMINALS THIS MORNING. A TRAILING RAIN AREA NOW IN
MISSOURI TO MOVE NORTHEAST AND CAUSE PRECIPITATION CHANCES TO
LINGER FOR KBRL INTO THE EARLY AFTERNOON HOURS. THIS PRECIPITATION
IS AHEAD OF A COLD FRONT THAT IS EXPECTED TO MOVE ACROSS THE
TERMINALS TONIGHT...GENERALLY BETWEEN LATE EVENING AND EARLY
TUESDAY MORNING. WINDS AHEAD OF THE FRONT TO BE SOUTH...GENERALLY
BETWEEN 5 AND 10 KTS. AS THE FRONT MOVES THROUGH THEY WILL GO
LIGHT AND VARIABLE FOR A WHILE BEFORE TURNING NORTHWEST...STILL 5
TO 10 KTS. SOME MODELS IMPLYING SOME MVFR CIGS TO ACCOMPANY THE
FRONT ITSELF...BUT NO LOW CLOUD FORMATION HAS APPEARED WHERE THEY
IMPLY IT SHOULD ALREADY BE FORMING AND HAVE LEFT OUT OF FORECAST. WILL
BE WATCHING FOR THIS POTENTIAL WITH LATER FORECASTS. LE
PREV DISCUSSION... /ISSUED 303 AM CST MON NOV 19 2012/
SYNOPSIS...
A BAND OF LIGHT RAIN IS MOVING ACROSS THE FORECAST AREA THIS
MORNING...FOLLOWED BY ANOTHER MASS OF RAIN IN WESTERN MISSOURI.
ALL THIS IS BEING DRIVEN BY A SHORTWAVE MOVING ACROSS THE
MIDWEST...WITH VORT MAXES OVER WESTERN IOWA...AND ANOTHER OVER
EASTERN KANSAS. THESE ARE MOVING ACROSS A NARROW PLUME OF GULF
MOISTURE EXTENDING FROM WEST TEXAS UP INTO WESTERN IOWA AS OF THE
00Z ANALYSIS LAST NIGHT. AT THE SURFACE...THERE IS A SURFACE LOW
OVER EASTERN SOUTH DAKOTA...WITH A TROUGH AXIS/WEAK COLD FRONT
EXTENDING SOUTH ACROSS NEBRASKA AND INTO KANSAS.
SHORT TERM...
THE SHORTWAVE WILL CONTINUE TO MOVE ACROSS THE AREA
TODAY...BRINGING THE CURRENT BAND ACROSS THE FORECAST AREA...
MAINLY THIS MORNING. RADAR RETURNS ARE RELATIVELY WEAK AND CIELING
HEIGHTS HAVE REMAINED MOSTLY ABOVE 5KFT. ALSO...AS THE BAND HAS
MOVED ACROSS LOCATIONS ONLY SOME HAVE REPORTED ANY PRECIPITATION...
AND NOT MORE THAN A FEW HUNDRETHS OF AN INCH OF RAIN AT ANY ONE
LOCATION. THUS...HAVE KEPT POPS IN THE CHANCE CATEGORY FOR
THIS MORNING. AS THIS WAVE CONTINUES EAST IT MOVES OUT OF THE
PLUME OF MOISTURE...EVEN THOUGH IT WILL DRAG SOME OF IT ALONG TO
CONTINUE SOME PRECIPITATION CHANCES. IN FACT...BY THE TIME THE
WAVE GETS TO THE EASTERN CWA THIS AFTERNOON HAVE LOWERED POPS TO
SLIGHT CHANCES. BY THIS EVENING WE SHOULD BE MAINLY DRY. CLOUD
COVER IS GOING TO KEEP TEMPERATURES FROM GETTING AS WARM AS WE DID
ON SUNDAY...BUT WE WILL HAVE HAD A WARMER START AND THE CONTINUED
WARM AIR ADVECTION AHEAD OF THE COLD FRONT. THUS...HAVE HIGH TEMPS
IN THE MID TO UPPER 50S. TONIGHT THE COLD FRONT ITSELF MOVES
THROUGH...BRINGING COLDER AIR TO THE REGION. EXPECT SOME LOWER
CLOUDS TO ACCOMPANY THE FRONT...BUT THE WESTERN HALF TO CLEAR OUT
ENOUGH FOR MIN TEMPS IN THE MID 30S...BUT STAYING IN THE 40S IN
THE EAST UNDER THE CLOUD COVER. LE
LONG TERM...TUESDAY THROUGH SUNDAY...
MILD TEMPERATURES THROUGH THANKSGIVING THEN COLDER.
TUESDAY THROUGH THANKSGIVING DAY...ABOVE NORMAL TEMPERATURES AS
RIDGE ALOFT BUILDS INTO THE CENTER OF THE COUNTRY. THIS WILL BE
AHEAD OF A STRONG STORM SYSTEM THAT WILL MOVE INTO THE NORTHERN
PLAINS BY THANKSGIVING DAY. HIGHS ARE EXPECTED TO BE IN THE 60S THIS
PERIOD WITH THE POTENTIAL FOR 70 IN OUR SOUTHERN CWA ON WEDNESDAY.
ECM/GFS/GEM STARTING TO INCREASE THE POTENTIAL FOR SHOWERS ON
THANKSGIVING AHEAD OF STRONG COLD FRONT. FOR NOW WILL HAVE SMALL
POPS ACROSS THE CWA AND IF MODELS ARE CONSISTENT WITH THIS SIGNAL
THEN POPS MAY NEED TO BE RAISED.
THURSDAY NIGHT THROUGH SATURDAY NIGHT...COLDER WEATHER RETURNS AS A
DEEPENING UPPER LEVEL LOW TRACKS FROM THE NORTHERN PLAINS TO THE
NORTHERN GREAT LAKES. 850 MB TEMPS DROP TO -12C IN THE CWA FRIDAY
INTO FRIDAY NIGHT. ANY SNOW SHOWERS ASSOCIATED WITH THIS STORM SYSTEM
SHOULD REMAIN NORTH OF THE DVN CWA. HIGHS WILL BE IN THE 40S WITH
LOWS IN THE 20S THIS PERIOD.
SUNDAY INTO EARLY NEXT WEEK...TEMPERATURES MODERATE AHEAD OF A MUCH
STRONGER TROUGH AND ARCTIC COLD FRONT THAT WILL BE ARRIVING INTO THE
DVN CWA ABOUT NOVEMBER 28.
HAASE
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
326 AM CST MON NOV 19 2012
.SHORT TERM /TODAY/...
LIGHT SHOWERS THAT TRAVERSED THE AREA OVERNIGHT ARE ABOUT TO CLEAR
OUT TO THE EAST AND SHOULD BE OVER IN OUR CWA BEFORE 12Z. WILL
HANDLE THESE WITH A PRE FIRST PERIOD AND GO DRY TODAY.
OTHERWISE...SATELLITE IMAGERY INDICATES THAT THE CLOUDS OVERHEAD
WILL CLEAR MORE QUICKLY AND THOROUGHLY THAN IS INDICATED BY MOST
SHORT RANGE MODELS. HAVE THUS ACCELERATED CLEARING SKIES THIS
MORNING AND INCREASED FORECAST HIGH TEMPERATURES BY A COUPLE OF
DEGREES. DESPITE THE RELATIVELY LIGHT SOUTHERLY FLOW WE SHOULD WARM
UP PRETTY NICELY...ESPECIALLY GIVEN THAT 09Z TEMPERATURES ARE IN THE
MID 40S TO LOWER 50S ACROSS THE AREA...AND MAY STILL BE A LITTLE TOO
COOL TODAY BUT AT THE HIGH END OF OR ABOVE MOS GUIDANCE WILL NOT GET
TOO AGGRESSIVE WITH THE WARMING.
.LONG TERM /TONIGHT THROUGH SUNDAY/...
WARM PATTERN WILL CONTINUE WITH DRY CONDITIONS TUE AND WED. LITTLE
CHANGE IN THE THINKING OF THE PAST FEW DAYS WITH H8 TEMPS STILL
EXPECTED TO GET INTO THE +11 TO +14 RANGE ON WED. GIVEN CURRENT
FORECAST HIGHS FOR WED IN THE UPPER 60S TO LOW 70S...HAVE HEADLINED
THE NEAR RECORD HIGHS FOR WED. THU CONTINUES TO BE TRICKY WITH THE
APPROACHING COLD FRONT AND SOME MOISTURE PUSHING IN AHEAD OF IT.
MODELS HAVE BEEN CONSISTENT WITH THE CLOUD COVER AND EVEN SOME
SHOWERS ACROSS THE SOUTHEAST. TAKING THAT INTO ACCOUNT HAVE TEMPS
LAID OUT IN ACCORDANCE WITH THE ECMWF DEPICTION WITH WARMER TEMPS
RELATIVE TO SURROUNDING IN A BAND FROM THE SOUTHWEST INTO THE NORTH
CENTRAL. FIRST COLD FRONT WILL PUSH THROUGH LATE THU AND THU NIGHT.
GEM AND ECMWF BOTH DEPICT A GOOD SECONDARY COLD FRONT PUSHING SOUTH
ACROSS THE STATE ON FRI. THE GFS MISSED THIS FEATURE. FOR THAT
REASON WILL MAKE ADJUSTMENTS DOWN ON TEMPS FOR FRI...FRI NIGHT...AND
SAT. RETURN TO WARMER WEATHER HEADING INTO SUN AND MON...BUT DON`T
THINK IT WILL LAST ALL THAT LONG THIS TIME. HIGH LAT BLOCKING IS
BEGINNING TO TAKE PLACE IN THE KARA SEA AREA AND IS LIKELY TO BRIDGE
WITH THE EASTERN PACIFIC RIDGE...ALLOWING FOR DEVELOPMENT OF MORE
CROSS POLAR FLOW AND COLDER TEMPS FOR MUCH OF CONUS.
&&
.AVIATION...19/06Z
SHOWER ACTIVITY WILL CONTINUE TO PRESS EAST NORTHEAST OVERNIGHT AND
LOOKS TO END AT DSM BY 07Z AT THE LATEST. ALO/OTM WILL BE AFFECTED
BY THE SHOWERS PAST 08Z AND NOT ANTICIPATING MUCH AFTER 12Z MONDAY
MORNING. THE LATEST HRRR HAS SHOWERS ENDING BY 11Z.
OTHERWISE...EXPECT VFR CONDITIONS THROUGHOUT THE FORECAST WITH A
WIND SHIFT TO THE WEST NORTHWEST LATE MONDAY AFTERNOON INTO THE
EVENING AS A WEAK TROUGH MOVES THROUGH THE STATE.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...JUNGBLUTH
LONG TERM...MS NOV 12
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1143 PM CST SUN NOV 18 2012
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TONIGHT/...
SOUTH FLOW WILL CONTINUE AT THE SURFACE TONIGHT OVER IOWA AS A SHORT
WAVE TROUGH CURRENTLY ALONG THE EASTERN COLORADO AND NEW MEXICO
BORDERS LIFTS RAPIDLY INTO IOWA. A BAND OF UPWARD MOTION AHEAD OF
THE SHORT WAVE WILL QUICKLY DEVELOP CLOUD COVER AND A BAND OF LIGHT
SHOWERS THIS EVENING. LOW TO MID LEVEL MOISTURE WILL TAP INTO THE
SYSTEM AS WELL...BUT IT APPEARS TO BE A LITTLE LATE TO PRODUCE MUCH
IN THE WAY OF PRECIPITATION...ESPECIALLY IN THE NORTH AND WEST OF
I-35. FORECAST SOUNDINGS INDICATE INSTABILITY WILL BE SLIM TO
NONE...SO ONLY LIGHT SHOWERS ARE EXPECTED. LOOKING AT A NUMBER OF
HIGH-RESOLUTION MODEL SOLUTIONS...IT APPEARS THAT SOUTHEAST PORTIONS
OF THE FORECAST AREA HAVE THE HIGHEST LIKELIHOOD OF SEEING THE
SHOWERS...SO THE HIGHEST POPS ARE LOCATED THERE BEFORE THE FORCING
ALOFT BEGINS TO EXIT TO THE EAST TOWARD MORNING. DUE TO THE SOUTH
FLOW...CLOUD COVER AND INCREASING MOISTURE...OVERNIGHT LOWS SHOULD
BE UNIFORMLY WARMER THAN LAST NIGHT.
.LONG TERM /MONDAY THROUGH SUNDAY/...
LITTLE CHANGES THROUGHOUT THE EXTENDED WITH DRY CONDITIONS EXPECTED
THROUGHOUT THE ENTIRE FORECAST PERIOD...WITH THE EXCEPTION OF ANY
LIGHT LINGERING PRECIP INITIALLY MONDAY MORNING ACROSS THE EXTREME
EASTERN CWA. OTHERWISE UPPER RIDGING STILL EXPECTED TO BUILD INTO
THE AREA WITH H85 TEMPS CLIMBING INTO THE TEENS CELSIUS WEDNESDAY
IN SOUTHERLY FLOW THROUGHOUT THE LOW LEVELS. STILL ANTICIPATE
TEMPERATURES WELL ABOVE AVERAGE FOR WED...WITH UPPER RIDGE
FLATTENING INTO THE THANKSGIVING DAY AND A BIT OF A COOL DOWN. WEAK
SHORTWAVE TROUGH DIVE SOUTHEAST INTO MINNESOTA AND THE GREAT LAKES
REGION BY FRIDAY...BRINGING A BACK DOOR COLD FRONT INTO THE CWA WITH
ANY ASSOCIATED PRECIPITATION REMAINING NORTH AND EAST OF THE CWA.
FLOW REMAINS LESS AMPLIFIED INTO THE WEEKEND AND NEXT WEEK...BUT A
WEAK RIDGE EXPECTED TO BUILD BACK INTO THE REGION FOR SUNDAY WITH
TEMPS ALOFT APPROACHING +10C OR HIGHER AGAIN. THEREFORE EXPECT
ANOTHER WARMER DAY FOR SUNDAY...WITH THE UPPER LEVELS TRANSITIONING
TO MORE OF A WEST COAST TROUGH INTO NEXT WEEK SUGGESTING A TREND
TOWARD A MORE ACTIVE PATTERN JUST BEYOND THE CURRENT FORECAST
PERIOD.
&&
.AVIATION...19/06Z
SHOWER ACTIVITY WILL CONTINUE TO PRESS EAST NORTHEAST OVERNIGHT AND
LOOKS TO END AT DSM BY 07Z AT THE LATEST. ALO/OTM WILL BE AFFECTED
BY THE SHOWERS PAST 08Z AND NOT ANTICIPATING MUCH AFTER 12Z MONDAY
MORNING. THE LATEST HRRR HAS SHOWERS ENDING BY 11Z.
OTHERWISE...EXPECT VFR CONDITIONS THROUGHOUT THE FORECAST WITH A
WIND SHIFT TO THE WEST NORTHWEST LATE MONDAY AFTERNOON INTO THE
EVENING AS A WEAK TROUGH MOVES THROUGH THE STATE.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...JUNGBLUTH
LONG TERM...BEERENDS
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1019 AM MST MON NOV 19 2012
.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 225 AM MST MON NOV 19 2012
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW WESTERLY ZONAL FLOW IN
PLACE ACROSS THE US...WITH SEVERAL LOW AMPLITUDE SHORTWAVE TROUGHS
EMBEDDED WITHIN MEAN FLOW. NEAREST SHORTWAVE TROUGH CURRENTLY
EXTENDS ACROSS EASTERN KS...WITH SUBSIDENCE IN PLACE BEHIND THIS
FEATURE OVER WESTERN KS. A SURFACE TROUGH AXIS CURRENTLY EXTENDS FROM
THE DAKOTAS AND ACROSS WESTERN KS...JUST EAST OF THE CWA BORDER.
OVERALL PATTERN WILL REMAIN QUIET THROUGH THE SHORT TERM...WITH MAIN
STORM TRACK WELL NORTH OF THE CWA AND WEAK SOUTHERN TRACK FAVORING
AREAS SOUTH AND EAST OF OUR CWA. PROGRESSIVE ZONAL PATTERN
TRANSITIONING TO SHORTWAVE RIDGING BY TUE...AND A RETURN TO W-SW FLOW
BY WED NIGHT AS THIS RIDGE SHIFTS EAST AND A SHORT WAVE TROUGH MOVES
WITHIN THE VICINITY OF THE CWA. THERE IS GOOD LARGE SCALE ASCENT
ACROSS CENTRAL KS WITH THIS FEATURE...CLOSE TO OUR EASTERN CWA BORDER.
HOWEVER...MOISTURE PROFILES ARE VERY DRY ESPECIALLY THROUGH ABOUT
600MB. I DECIDED TO KEEP FORECAST DRY FOR NOW IN OUR EASTERN CWA
WITH A FEW SPRINKLES POSSIBLE AT MOST.
UNSEASONABLY WARM TEMPERATURES IN THE UPPER 60S/LOW 70S ARE EXPECTED
THE NEXT THREE DAYS...WITH THE WARMEST ON WED AS LEE TROUGH
STRENGTHENS ALONG KS/CO BORDER. WITH INCREASED AFTERNOON MIXING...WE
SHOULD SEE VERY LOW RH VALUES WED AFTERNOON. CURRENT TROUGH POSITION
KEEPS THE STRONGEST WINDS OVER THE EASTERN CWA WHERE HIGHER RH
VALUES SHOULD BE...SO IT STILL LOOKS LIKE WE WONT NEED A RFW. THIS
WILL PROBABLY NEED TO BE WATCHED SINCE IT COULD BE CLOSE.
.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 225 AM MST MON NOV 19 2012
THURSDAY THROUGH SUNDAY...NORTHERN STREAM SYSTEM WILL PUSH A COLD
FRONT THROUGH EARLY ON THANKSGIVING DAY. WINDS MAY NEED TO BE A
LITTLE STRONGER THAT WHAT THE CRH_INIT GAVE ME ON THURSDAY BUT
APPEAR IN THE BALL PARK. THIS WILL BE SOMETHING THAT UPCOMING SHIFTS
WILL NEED TO WATCH. THERE WILL BE COME COOL DOWN ON THURSDAY WITH
THE COOLEST TEMPERATURES TO ARRIVE ON FRIDAY. AFTER THAT...
TEMPERATURES WILL MODERATE UNTIL LATE SUNDAY WHEN THE NEXT COLD
FRONT WILL ARRIVE. MAIN STORM TRACK/LIFT/MOISTURE REMAIN WELL NORTH
OF THE AREA SO THE DRY FORECAST LOOKS FINE AS DOES ALL THE INIT
GRIDS THAT I WAS GIVEN.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1014 AM MST MON NOV 19 2012
VFR CONDITIONS EXPECTED AT BOTH KGLD AND KMCK THROUGH THE TAF
PERIOD. WINDS WILL BE LIGHT AS HIGH PRESSURE SETTLES INTO THE
REGION BEHIND A WEAK COLD FRONT. A FEW HIGH CLOUDS WILL SPILL
ACROSS THE ROCKIES AND INTO THE PLAINS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BULLER
AVIATION...024
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
919 AM CST MON NOV 19 2012
...UPDATED FORECAST FOR LOCALLY DENSE FOG THIS MORNING...
.UPDATE...
ISSUED AT 918 AM CST MON NOV 19 2012
HAVE UPDATED THE FORECAST TO INCLUDE SOME LOCALLY DENSE FOG IN
THE AREA AROUND PRATT, COLDWATER AND ASHLAND FOR A FEW HOURS THIS
MORNING. TEMPERATURE/DEWPOINT SPREADS HAVE NARROWED CLOSELY IN THAT
AREA EARLY THIS MORNING. THE FOG SHOULD BURN OFF BY AROUND 10 AM
TO 11 AM AS RUC MODEL SOUNDINGS FOR THAT AREA SHOW THE LOW LEVEL
INVERSION AND BOUNDARY LAYER SATURATION DISSIPATING FAIRLY QUICKLY
THIS MORNING.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 212 AM CST MON NOV 19 2012
THE GOING FORECAST SEEMS TO BE ON TRACK, IN LINE WITH CURRENT SHORT
TERM MODELS, AND WELL WITHIN TOLERANCE OF SURROUNDING ISC GRIDS.
TODAY WILL START OFF WITH A WEAK SURFACE TROUGH ORIENTED FROM NORTH-
NORTHEAST TO SOUTH-SOUTHWEST FROM NEAR WAKEENEY TO HUGOTON. WINDS
EAST OF THE TROUGH WILL BE SOUTH TO SOUTHWEST AT 7 TO 10 MPH THIS
MORNING, AND WEST OF THE TROUGH WILL BE FROM THE WEST TO
NORTHWEST AT SIMILAR SPEEDS. THE TROUGH SHOULD WORK EAST LATE
THIS MORNING, AND SHIFT WINDS TO THE NORTH BEHIND THE TROUGH
PASSAGE. AN EXITING SHORT WAVE ALOFT WILL BRING NORTHWEST FLOW
INITIALLY, BUT SHIFT TO MORE OF A ZONAL FLOW THIS AFTERNOON. A
FEW CIRRUS CLOUDS MAY STREAM ACROSS IN THE ZONAL FLOW, BUT ARE
EXPECTED TO BE THIN CLOUDS AND NOT HAVE MUCH INFLUENCE ON THE
SOLAR HEATING. MAXIMUM TEMPERATURES TODAY WILL BE CLOSE TO
YESTERDAY OR A BIT WARMER, RANGING FROM NEAR 70F DEGREES ALONG THE
OKLAHOMA BORDER TO THE UPPER 60S NORTH OF I-70 INTERSTATE.
TONIGHT, AN UPPER LEVEL RIDGE WILL BUILD IN FROM THE WEST, AND BRING
CLEAR SKIES TO SOUTHWESTERN KANSAS. WINDS WILL BE LIGHT AND FROM
THE NORTH. SOME COLD AIR WILL FILTER IN AT LOWER LEVELS, PRODUCING
MINIMUM TEMPERATURES IN THE LOWER 30S NORTHWEST OF A HAYS TO JOHNSON
CITY LINE, RANGING TO MINIMUMS AROUND 40F DEGREES IN THE MEDICINE LODGE
AREA. AS FOR MODEL GUIDANCE, THE GFS MOS IS WARMER, AND THE NAM
MODEL COOLER. I LEANED CLOSER TO THE COOLER NAM MODEL GUIDANCE,
AS IT HAS BEEN CLOSER TO REALITY LATELY THAN THE GFS MODEL HAS BEEN.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 351 AM CST MON NOV 19 2012
UPPER-LEVEL RIDGING WILL BE SITUATED ACROSS THE HIGH PLAINS ON
TUESDAY, WITH WEAK SURFACE LEE TROUGHING ACROSS THE NORTHERN PLAINS.
TEMPERATURES SHOULD REACH INTO THE UPPER 60S TO LOWER 70S.
BY WEDNESDAY, A WEAK SHORTWAVE TROUGH WILL BE EJECTING FROM BAJA
CALIFORNIA INTO THE TEXAS BIG BEND. A STRONGER SHORTWAVE TROUGH WILL
MOVE ONSHORE INTO THE NORTHWESTERN UNITED STATES. LEE TROUGHING WILL
INTENSITY IN RESPONSE TO MID-LEVEL SOUTHWESTERLY FLOW ACROSS THE
ROCKIES. HIGH TEMPERATURES OUGHT TO REACH INTO THE LOWER TO EVEN
MIDDLE 70S. VERY MILD TEMPERATURES CAN BE EXPECTED WEDNESDAY NIGHT
AS LOW-LEVEL MOISTURE INCREASES FROM THE GULF OF MEXICO (DEWPOINTS
IN THE LOWER TO MID 40S) AND WINDS REMAIN AT LEAST 10 KTS.
TEMPERATURES MAY NOT FALL BELOW THE LOWER 50S FROM DODGE CITY
EASTWARD TO MEDICINE LODGE.
BY THURSDAY, THE SOUTHERN STREAM SYSTEM WILL BE MOVING ACROSS THE
SOUTHERN PLAINS WHILE THE STRONGER NORTHERN STREAM SHORTWAVE TROUGH
PROGRESSES ACROSS THE NORTHERN PLAINS. A COLD FRONT ASSOCIATED WITH
THE NORTHERN SYSTEM WILL BE PASSING THROUGH SOUTHWEST KANSAS DURING
THE LATE MORNING AND EARLY AFTERNOON. CONTINUED RETURN FLOW FROM
THE GULF OF MEXICO AHEAD OF THE FRONT WILL LEAD TO DEWPOINTS IN THE
LOWER 50S IN SOUTH CENTRAL KANSAS BY AFTERNOON. SURFACE BASED CAPE
VALUES MAY APPROACH 500 J/KG BY AFTERNOON GIVEN HIGH TEMPERATURES IN
THE LOWER 70S. A FEW NON-SEVERE THUNDERSTORMS MAY DEVELOP. THE EXACT
PLACEMENT OF THE STORMS WILL DEPEND ON THE SPEED OF THE FRONT. THE
BEST CHANCE OF STORMS WILL BE FROM MEDICINE LODGE EASTWARD.
TEMPERATURES WILL BE FAIRLY MILD EVEN BEHIND THE FRONT AS THE MUCH
COOLER AIR WILL BE TRAILING WELL BEHIND THE WIND SHIFT.
COOLER AIR WILL MOVE INTO WESTERN KANSAS BY THURSDAY NIGHT AND
FRIDAY BEHIND THE FRONT. TEMPERATURES WILL LIKELY DROP INTO THE
40S BY MIDNIGHT, WHICH WOULD PRECLUDE DODGE CITY FROM HAVING
A RECORD HIGH MINIMUM TEMPERATURE FOR THURSDAY THE 22ND. THE RECORD
VALUE IS 46 DEGREES SET IN 1885. HIGHS FRIDAY WILL BE COOLER IN THE
MID TO UPPER 50S. HIGHS SHOULD RECOVER INTO THE 60S BY SATURDAY AS
LEE TROUGHING DEVELOPS ACROSS THE HIGH PLAINS IN RESPONSE TO WESTERLY
FLOW ACROSS THE ROCKIES.
BIG DIFFERENCES START TO APPEAR IN THE MODELS BY SUNDAY NOVEMBER
25TH INTO THE 27TH. THE ECMWF AND GEM DEVELOP AN UPPER-LEVEL RIDGE
TO THE WEST OF ALASKA AND A TROUGH FROM SOUTHWESTERN CANADA INTO THE
NORTHWESTERN UNITED STATES. THE AMPLITUDE OF THIS RIDGE-TROUGH
COMBINATION IS THE KEY TO THE FORECAST. MORE AMPLIFICATION WOULD MEAN
THAT ARCTIC HIGH PRESSURE WOULD SLIDE SOUTHEASTWARD INTO THE
NORTHERN AND CENTRAL PLAINS BY THE 26TH OR 27TH. IF THE PATTERN IS
LESS AMPLIFIED, THEN TEMPERATURES WOULD STAY CLOSER TO CLIMATOLOGY.
THE ECMWF HAS BEEN OSCILLATING BACK AND FORTH BETWEEN A MORE
AMPLIFIED AND LESS AMPLIFIED PATTERN, SO CONFIDENCE IN THE ARRIVAL
OF ARCTIC AIR AND PRECIPITATION CHANCES ARE VERY LOW.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 554 AM CST MON NOV 19 2012
A WEAK COLD FRONT WAS PASSING ACROSS SOUTHWEST KANSAS THIS MORNING.
WINDS WILL GRADUALLY SHIFT FROM THE WEST TO THE NORTH THROUGH 00Z,
WITH SPEEDS 10 KTS OR LESS. IN THE ABSENCE OF LOW LEVEL MOISTURE, VFR
CONDITIONS WILL PERSIST.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 69 36 68 40 / 0 0 0 0
GCK 69 33 68 38 / 0 0 0 0
EHA 68 35 68 38 / 0 0 0 0
LBL 69 32 69 39 / 0 0 0 0
HYS 68 32 69 41 / 0 0 0 0
P28 69 41 72 42 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GERARD
SHORT TERM...BURKE
LONG TERM...FINCH
AVIATION...FINCH
AREA FORECAST DISCUSSION
NWS GOODLAND KS
413 AM MST MON NOV 19 2012
.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 225 AM MST MON NOV 19 2012
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW WESTERLY ZONAL FLOW IN
PLACE ACROSS THE US...WITH SEVERAL LOW AMPLITUDE SHORTWAVE TROUGHS
EMBEDDED WITHIN MEAN FLOW. NEAREST SHORTWAVE TROUGH CURRENTLY
EXTENDS ACROSS EASTERN KS...WITH SUBSIDENCE IN PLACE BEHIND THIS
FEATURE OVER WESTERN KS. A SURFACE TROUGH AXIS CURRENTLY EXTENDS FROM
THE DAKOTAS AND ACROSS WESTERN KS...JUST EAST OF THE CWA BORDER.
OVERALL PATTERN WILL REMAIN QUIET THROUGH THE SHORT TERM...WITH MAIN
STORM TRACK WELL NORTH OF THE CWA AND WEAK SOUTHERN TRACK FAVORING
AREAS SOUTH AND EAST OF OUR CWA. PROGRESSIVE ZONAL PATTERN
TRANSITIONING TO SHORTWAVE RIDGING BY TUE...AND A RETURN TO W-SW FLOW
BY WED NIGHT AS THIS RIDGE SHIFTS EAST AND A SHORT WAVE TROUGH MOVES
WITHIN THE VICINITY OF THE CWA. THERE IS GOOD LARGE SCALE ASCENT
ACROSS CENTRAL KS WITH THIS FEATURE...CLOSE TO OUR EASTERN CWA BORDER.
HOWEVER...MOISTURE PROFILES ARE VERY DRY ESPECIALLY THROUGH ABOUT
600MB. I DECIDED TO KEEP FORECAST DRY FOR NOW IN OUR EASTERN CWA
WITH A FEW SPRINKLES POSSIBLE AT MOST.
UNSEASONABLY WARM TEMPERATURES IN THE UPPER 60S/LOW 70S ARE EXPECTED
THE NEXT THREE DAYS...WITH THE WARMEST ON WED AS LEE TROUGH
STRENGTHENS ALONG KS/CO BORDER. WITH INCREASED AFTERNOON MIXING...WE
SHOULD SEE VERY LOW RH VALUES WED AFTERNOON. CURRENT TROUGH POSITION
KEEPS THE STRONGEST WINDS OVER THE EASTERN CWA WHERE HIGHER RH
VALUES SHOULD BE...SO IT STILL LOOKS LIKE WE WONT NEED A RFW. THIS
WILL PROBABLY NEED TO BE WATCHED SINCE IT COULD BE CLOSE.
.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 225 AM MST MON NOV 19 2012
THURSDAY THROUGH SUNDAY...NORTHERN STREAM SYSTEM WILL PUSH A COLD
FRONT THROUGH EARLY ON THANKSGIVING DAY. WINDS MAY NEED TO BE A
LITTLE STRONGER THAT WHAT THE CRH_INIT GAVE ME ON THURSDAY BUT
APPEAR IN THE BALL PARK. THIS WILL BE SOMETHING THAT UPCOMING SHIFTS
WILL NEED TO WATCH. THERE WILL BE COME COOL DOWN ON THURSDAY WITH
THE COOLEST TEMPERATURES TO ARRIVE ON FRIDAY. AFTER THAT...
TEMPERATURES WILL MODERATE UNTIL LATE SUNDAY WHEN THE NEXT COLD
FRONT WILL ARRIVE. MAIN STORM TRACK/LIFT/MOISTURE REMAIN WELL NORTH
OF THE AREA SO THE DRY FORECAST LOOKS FINE AS DOES ALL THE INIT
GRIDS THAT I WAS GIVEN.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 413 AM MST MON NOV 19 2012
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD WITH ONLY PASSING
HIGH CLOUDS. WINDS WILL SHIFT FROM THE WEST TO THE NORTHWEST AS A
SURFACE TROUGH SHIFTS EAST...REMAINING BELOW 12KT THROUGH THE
PERIOD. WINDS WILL BECOME LIGHT AND VARIABLE AROUND SUNSET AS
DAYTIME MIXING ENDS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BULLER
AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
225 AM MST MON NOV 19 2012
.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 225 AM MST MON NOV 19 2012
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW WESTERLY ZONAL FLOW IN
PLACE ACROSS THE US...WITH SEVERAL LOW AMPLITUDE SHORTWAVE TROUGHS
EMBEDDED WITHIN MEAN FLOW. NEAREST SHORTWAVE TROUGH CURRENTLY
EXTENDS ACROSS EASTERN KS...WITH SUBSIDENCE IN PLACE BEHIND THIS
FEATURE OVER WESTERN KS. A SURFACE TROUGH AXIS CURRENTLY EXTENDS FROM
THE DAKOTAS AND ACROSS WESTERN KS...JUST EAST OF THE CWA BORDER.
OVERALL PATTERN WILL REMAIN QUIET THROUGH THE SHORT TERM...WITH MAIN
STORM TRACK WELL NORTH OF THE CWA AND WEAK SOUTHERN TRACK FAVORING
AREAS SOUTH AND EAST OF OUR CWA. PROGRESSIVE ZONAL PATTERN
TRANSITIONING TO SHORTWAVE RIDGING BY TUE...AND A RETURN TO W-SW FLOW
BY WED NIGHT AS THIS RIDGE SHIFTS EAST AND A SHORT WAVE TROUGH MOVES
WITHIN THE VICINITY OF THE CWA. THERE IS GOOD LARGE SCALE ASCENT
ACROSS CENTRAL KS WITH THIS FEATURE...CLOSE TO OUR EASTERN CWA BORDER.
HOWEVER...MOISTURE PROFILES ARE VERY DRY ESPECIALLY THROUGH ABOUT
600MB. I DECIDED TO KEEP FORECAST DRY FOR NOW IN OUR EASTERN CWA
WITH A FEW SPRINKLES POSSIBLE AT MOST.
UNSEASONABLY WARM TEMPERATURES IN THE UPPER 60S/LOW 70S ARE EXPECTED
THE NEXT THREE DAYS...WITH THE WARMEST ON WED AS LEE TROUGH
STRENGTHENS ALONG KS/CO BORDER. WITH INCREASED AFTERNOON MIXING...WE
SHOULD SEE VERY LOW RH VALUES WED AFTERNOON. CURRENT TROUGH POSITION
KEEPS THE STRONGEST WINDS OVER THE EASTERN CWA WHERE HIGHER RH
VALUES SHOULD BE...SO IT STILL LOOKS LIKE WE WONT NEED A RFW. THIS
WILL PROBABLY NEED TO BE WATCHED SINCE IT COULD BE CLOSE.
.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 225 AM MST MON NOV 19 2012
THURSDAY THROUGH SUNDAY...NORTHERN STREAM SYSTEM WILL PUSH A COLD
FRONT THROUGH EARLY ON THANKSGIVING DAY. WINDS MAY NEED TO BE A
LITTLE STRONGER THAT WHAT THE CRH_INIT GAVE ME ON THURSDAY BUT
APPEAR IN THE BALL PARK. THIS WILL BE SOMETHING THAT UPCOMING SHIFTS
WILL NEED TO WATCH. THERE WILL BE COME COOL DOWN ON THURSDAY WITH
THE COOLEST TEMPERATURES TO ARRIVE ON FRIDAY. AFTER THAT...
TEMPERATURES WILL MODERATE UNTIL LATE SUNDAY WHEN THE NEXT COLD
FRONT WILL ARRIVE. MAIN STORM TRACK/LIFT/MOISTURE REMAIN WELL NORTH
OF THE AREA SO THE DRY FORECAST LOOKS FINE AS DOES ALL THE INIT
GRIDS THAT I WAS GIVEN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1000 PM MST SUN NOV 18 2012
VFR THROUGH THE PERIOD AT KGLD AND KMCK. SFC TROUGH TO MOVE
THROUGH WITH LIGHT W/NW WINDS BEHIND IT UNDER SCATTERED MID LEVEL
CLOUDINESS. FOR MONDAY N/NW WINDS 10KTS OR SO AT BOTH SITES BY
LATE MORNING AS TROUGH MOVES THROUGH. SOME HIGH LEVEL CLOUDS MOVE
IN DURING THE AFTERNOON.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BULLER
AVIATION...99
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
822 AM EST MON NOV 19 2012
.SYNOPSIS...
ABOVE NORMAL TEMPERATURES ARE THE THEME THIS HOLIDAY WORK WEEK.
WEATHER WILL NOT BE OBSTACLE FOR THOSE TRAVELING BEFORE...DUE TO THE
ONLY SYSTEM THROUGH THANKSGIVING BEING ONE WHICH WILL PRODUCE
SPRINKLES AT BEST TUESDAY INTO EARLY WEDNESDAY. A STRONG FRONT
CROSSES FRIDAY NIGHT INTO SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AREA OF STRATOCU EAST OF THE MOUNTAINS IS SLOWLY CREEPING INTO THE DUJ
VICINITY AND IT HAS REACHED GARRETT COUNTY. UPDATED SKY GRIDS TO
REFLECT THESE TRENDS AND ALLOW THEM TO BURN OFF AROUND 15Z BASED
ON LLVL RH PROGS FROM THE HRRR AND NAM12. CIRRUS ADVANCING IN FROM
THE WEST WILL HINDER SUNSHINE A LITTLE...BUT WITH H8 TEMPS 1C
WARMER THAN YDY...STILL FEEL CONFIDENT THAT MAXT WILL MIRROR
SUNDAY`S VALUES.
TWEAKED HOURLY TEMPS TONIGHT TO REFLECT FASTER DROP OFF AFTER
SUNSET.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
THE MAIN FEATURE OF THE SHORT TERM PERIOD WILL BE THE AMPLIFIED
FLOW ALOFT AS THE AFOREMENTIONED SHORTWAVE TROUGH DEEPENS WITH
PROGRESSION ACROSS THE GREAT LAKES. THAT DISTURBANCE IS NOT
PROGGED TO TAP A DEEP MOISTURE SOURCE AND MEASURABLE PRECIPITATION
CHANCES ARE SMALL WITH ITS CROSSING LATER ON TUESDAY AND EARLY WEDNESDAY.
CURRENT EXPECTATIONS ARE THAT SUFFICIENT MID LEVEL MOISTURE WILL
ACCOMPANY THE SYSTEM FOR SOME SPRINKLES TO MAR THE LATE AFTN AND
AFTER DARK WEATHER PICTURE. HAVE INTRODUCED A SLIGHT SHOWER CHANCE
FOR THAT TIME PERIOD...BUT AGAIN...THINK DRIER AIR IN THE LOW
LEVELS WL INHIBIT MEASURABLE RAIN.
THEREAFTER...THE MODEL FORECAST IS FOR SHORTWAVE...BUT STILL
FAIRLY AMPLIFIED...RIDGING TO BUILD FOR WEDNESDAY AND THURSDAY.
DRY...AND WARMER WEATHER IS THUS FORECAST FOR THE HOLIDAY...WITH
TEMPS APPROXIMATELY 10 DEGREES ABOVE THE AVERAGES.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
THE GFS AND ECMWF MODEL FORECAST IS OF ANOTHER DEEP TROUGH
DIGGING ACROSS THE GREAT LAKES BY LATE WEEK. HENCE...THE POST-
THANKSGIVING PROGNOSIS IS OF INCREASED PRECIP CHANCES AND MORE
SEASONABLE TEMPERATURES.
&&
.AVIATION /13Z MONDAY THROUGH FRIDAY/...
MVFR/IFR VIS RESTRICTIONS WILL LIFT BY 14Z OWING TO VFR WEATHER.
MID AND HIGH CLOUDS WILL BE THE THEME TODAY WITH LIGHT WINDS. DUJ
COULD SEE A PERIOD OF BKN025 THROUGH 15Z AS STRATOCU TRIES TO
ADVECT IN FROM THE EAST.
.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
PREVALENT VFR WITH ONLY MORNING FOG POSING POTENTIAL RESTRICTIONS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...98
NEAR TERM...98
SHORT TERM...15
AVIATION...98/34
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1137 AM CST MON NOV 19 2012
.SHORT TERM...
ISSUED AT 314 AM CST MON NOV 19 2012
(TODAY)
MAIN CONCERN TODAY WILL BE PRECIPITATION CHANCES. THIN BAND OF
-SHRA EXTENDING FROM SERN IA INTO CNTRL MO HAS BEEN SHOWING SOME
DECREASE IN INTENSITY IN THE LAST HALF HOUR. SURFACE OBS HAS SHOWN
NO MORE THAN A BRIEF PERIOD OF TRACE -RA WITH CEILINGS REMAIN ABOVE
6000FT AGL. THIS LINE IS BEING FORCED BY A THIN AREA OF LOW LEVEL
MOISTURE CONVERGENCE UNDER A SUBTLE SHORTWAVE TROUGH. THE RAP IS
SHOWING THIS FORCING WEAKENING THE NEXT FEW HOURS AS IT MOVES
NORTHEAST...SO WILL SHOW SCT POPS DIMINISHING TO ISOLD OVER NERN
MO/W CNTRL IL BETWEEN 12-15Z. A MORE SUBSTANTIAL AREA OF -RA IS
CURRENTLY ENTERING SWRN MO AHEAD OF SHORTWAVE NOW OVER THE CENTRAL
PLAINS. RAP/GFS/WRF MODELS ARE SHOWING THIS WAVE DAMPENING OUT
TODAY AS A STRONGER SHORTWAVE BEGINS TO DIG SOUTHEASTWARD OUT OF
THE NORTHERN PLAINS. NET EFFECT WILL BE THAT LOW-MID LEVEL FORCING
FOR THIS SECOND AREA OF RAIN WILL DIMINISH THROUGH THE DAY AS IT
MOVES NORTHEAST INTO THE CWA. TIME CROSS SECTIONS FROM THE VARIOUS
MODELS ARE SHOWING A NOTABLE LAYER OF DRY AIR REMAINING AT AND
BELOW 850MB OVER THE SOUTHERN AND EASTERN PART OF THE CWA. THE
DIMINISHING FORCING AND DRY AIR CALL FOR MAINLY CHANCE POPS OVER
CNTRL/NERN MO AND W CNTRL IL WITH JUST SLIGHT CHANCES ELSEWHERE.
EXPECT MOSTLY CLOUDY/CLOUDY SKIES OVER MOST OF THE CWA TODAY...SO
WILL GO WITH A BLEND OR LEAN TOWARD THE COOLER NAM MOS TO
TEMPERATURES TODAY.
BRITT
&&
.LONG TERM...
ISSUED AT 314 AM CST MON NOV 19 2012
(TONIGHT THROUGH SUNDAY)
A SHORTWAVE WILL DROP SEWD THROUGH THE REGION TGT AND TUE SENDING A
WEAK COLD FRONT THROUGH OUR FORECAST AREA LATE TGT AND TUE MRNG.
ALTHOUGH MOST OF THE PRECIPITATION WILL SHIFT E OF THE AREA BY THIS
EVNG...IT APPEARS THAT THERE MAY STILL BE SOME SPRINKLES ACROSS
MAINLY SERN MO AND IL WITH WEAK LOW LEVEL WAA AHEAD OF THE FRONT
AND LINGERING LOW-MID LEVEL MOISTURE. SHOULD SEE GRADUAL CLEARING
FROM NW TO SE LATE TGT AND TUE AS THE LOW LEVEL MOISTURE GETS
SHUNTED TO THE SE WITH WEAK CAA ON TUE BEHIND THE COLD FRONT/850
MB TROUGH. TEMPERATURES WILL STILL BE ABOVE NORMAL ON TUE. COOLER
LOW TEMPERATURES CAN BE EXPECTED TUE NGT DUE TO A CLEAR SKY AND
LIGHT SFC WIND WITH A RELATIVELY WEAK SFC RIDGE OVER OUR AREA. AN
UPPER LEVEL RIDGE OVER MO...ALONG WITH FULL SUNSHINE AND SFC WINDS
BECOMING SLY WILL LEAD TO UNSEASONABLY WARM CONDITIONS FOR NERN
AND CNTRL MO ON WED. THESE WARM CONDITIONS WILL CONTINUE WED NGT
AND THANKSGIVING DAY DUE TO INCREASING S-SWLY LOW LEVEL WINDS.
ALTHOUGH THE ECMWF AND GFS MODELS STILL HAVE DIFFERENCES FOR THU
AND FRI THERE SOLUTIONS HAVE BECOME MORE SIMILAR THAN THEY WERE
THE PAST COUPLE OF DAYS. IT APPEARS THAT THE GFS HAS SOME FEEDBACK
PROBLEMS WED NGT AND THU AND IS LIKELY BRINGING PRECIPITATION
INTO OUR AREA A LITTLE TOO EARLY ON THU. PREFER THE ECMWF MODEL
WHICH HAS MOST OF THE PRECIPITATION THU NGT AS AN UPPER LEVEL LOW
MOVES SEWD THROUGH THE NRN PLAINS SENDING A STRONG COLD FRONT
SEWD THROUGH OUR AREA THU NGT. THE GFS IS NOW COLDER THAN THE
ECMWF MODEL THU NGT INTO FRI MRNG AND BRINGS THE ZERO DEGREE C
850 MB ISOTHERM SEWD TO STL BY 12Z FRI. THE ECMWF MODEL THOUGH IS
A LITTLE SLOWER AND DEEPER WITH THE UPPER LEVEL LOW MOVING THROUGH
THE NRN PORTION OF THE GREAT LAKES REGION ON FRI AND BRINGS
COLDER AIR INTO OUR REGION FRI AFTN THAN THE GFS. WILL TREND
COLDER WITH TEMPERATURES FRI AND FRI NGT ALTHOUGH NOT AS COLD AS
THE ECMWF MODEL WOULD IMPLY. A WARMING TREND WILL BEGIN ON SAT OR
SAT NGT ALTHOUGH WILL TRY TO FOLLOW THE SLOWER WARMING OF THE
ECMWF MODEL. NEXT CHANCE OF PRECIPITATION SHOULD HOLD OFF TIL SUN
NGT AS A STORM SYSTEM TAKES SHAPE OVER THE SRN PLAINS.
GKS
&&
.AVIATION...
ISSUED AT 1127 AM CST MON NOV 19 2012
DRY LOW LEVEL AIR HAS TAKEN ITS TOLL ON BATCH OF RAIN SHOWERS THAT
MOVED IN FROM CENTRAL MISSOURI THIS MORNING. ONLY ISOLATED
SHOWERS OR SPRINKLES REMAIN AND RADAR TRENDS CONFIRM THAT EVEN
THIS CONTINUES TO DIMINISH AS IT PROGRESSES INTO ILLINOIS. CLOUD
BASE GENERALLY VFR...OTHER THAN A SWATH OF MVFR FROM NORTHEAST
MISSOURI TO WEST CENTRAL ILLINOIS. CLOUD COVER SLOWLY MOVING
EAST...WITH CLEARING LINE ALREADY IN CENTRAL MISSOURI. BELIEVE
CLOUD COVER WILL HOLD TOUGH ACROSS EASTERN MISSOURI AND ILLINOIS
TONIGHT WITH MODEL GUIDANCE SHOWING LOWERING OF CEILING HEIGHTS
INTO MVFR CATEGORY. NOT READY TO COMPLETE BITE OFF ON THIS GIVEN
SIGNIFICANT TEMPERATURE/DEWPOINT SPREADS OF +20 ALONG AND EAST OF
THE MISSISSIPPI RIVER. SHOULD SEE IMPROVEMENT TOMORROW AND
CLEARING AS WIND SHIFTS TO THE NORTHWEST WITH FROPA.
SPECIFICS FOR KSTL...
VFR CONDITIONS PREVAIL AS DRY LOW LEVELS HAVE PROHIBITED RAINFALL.
TREND IS FOR CEILING TO GRADUALLY LOWER THIS EVENING AS LOW LEVEL
MOISTURE CONTINUES TO MOVE INTO THE AREA FROM THE SOUTH. NOT SURE
THAT WE WILL SEE MVFR CEILINGS AS MODEL GUIDANCE SUGGESTS.
CLEARING EXPECTED ON TUESDAY MORNING AS WIND SHIFTS TO THE
NORTHWEST BEHIND A COLD FRONT.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
525 AM CST MON NOV 19 2012
.SHORT TERM...
ISSUED AT 314 AM CST MON NOV 19 2012
(TODAY)
MAIN CONCERN TODAY WILL BE PRECIPITATION CHANCES. THIN BAND OF
-SHRA EXTENDING FROM SERN IA INTO CNTRL MO HAS BEEN SHOWING SOME
DECREASE IN INTENSITY IN THE LAST HALF HOUR. SURFACE OBS HAS SHOWN
NO MORE THAN A BRIEF PERIOD OF TRACE -RA WITH CEILINGS REMAIN ABOVE
6000FT AGL. THIS LINE IS BEING FORCED BY A THIN AREA OF LOW LEVEL
MOISTURE CONVERGENCE UNDER A SUBTLE SHORTWAVE TROUGH. THE RAP IS
SHOWING THIS FORCING WEAKENING THE NEXT FEW HOURS AS IT MOVES
NORTHEAST...SO WILL SHOW SCT POPS DIMINISHING TO ISOLD OVER NERN
MO/W CNTRL IL BETWEEN 12-15Z. A MORE SUBSTANTIAL AREA OF -RA IS
CURRENTLY ENTERING SWRN MO AHEAD OF SHORTWAVE NOW OVER THE CENTRAL
PLAINS. RAP/GFS/WRF MODELS ARE SHOWING THIS WAVE DAMPENING OUT
TODAY AS A STRONGER SHORTWAVE BEGINS TO DIG SOUTHEASTWARD OUT OF
THE NORTHERN PLAINS. NET EFFECT WILL BE THAT LOW-MID LEVEL FORCING
FOR THIS SECOND AREA OF RAIN WILL DIMINISH THROUGH THE DAY AS IT
MOVES NORTHEAST INTO THE CWA. TIME CROSS SECTIONS FROM THE VARIOUS
MODELS ARE SHOWING A NOTABLE LAYER OF DRY AIR REMAINING AT AND
BELOW 850MB OVER THE SOUTHERN AND EASTERN PART OF THE CWA. THE
DIMINISHING FORCING AND DRY AIR CALL FOR MAINLY CHANCE POPS OVER
CNTRL/NERN MO AND W CNTRL IL WITH JUST SLIGHT CHANCES ELSEWHERE.
EXPECT MOSTLY CLOUDY/CLOUDY SKIES OVER MOST OF THE CWA TODAY...SO
WILL GO WITH A BLEND OR LEAN TOWARD THE COOLER NAM MOS TO
TEMPERATURES TODAY.
BRITT
&&
.LONG TERM...
ISSUED AT 314 AM CST MON NOV 19 2012
(TONIGHT THROUGH SUNDAY)
A SHORTWAVE WILL DROP SEWD THROUGH THE REGION TGT AND TUE SENDING A
WEAK COLD FRONT THROUGH OUR FORECAST AREA LATE TGT AND TUE MRNG.
ALTHOUGH MOST OF THE PRECIPITATION WILL SHIFT E OF THE AREA BY THIS
EVNG...IT APPEARS THAT THERE MAY STILL BE SOME SPRINKLES ACROSS
MAINLY SERN MO AND IL WITH WEAK LOW LEVEL WAA AHEAD OF THE FRONT
AND LINGERING LOW-MID LEVEL MOISTURE. SHOULD SEE GRADUAL CLEARING
FROM NW TO SE LATE TGT AND TUE AS THE LOW LEVEL MOISTURE GETS
SHUNTED TO THE SE WITH WEAK CAA ON TUE BEHIND THE COLD FRONT/850
MB TROUGH. TEMPERATURES WILL STILL BE ABOVE NORMAL ON TUE. COOLER
LOW TEMPERATURES CAN BE EXPECTED TUE NGT DUE TO A CLEAR SKY AND
LIGHT SFC WIND WITH A RELATIVELY WEAK SFC RIDGE OVER OUR AREA. AN
UPPER LEVEL RIDGE OVER MO...ALONG WITH FULL SUNSHINE AND SFC WINDS
BECOMING SLY WILL LEAD TO UNSEASONABLY WARM CONDITIONS FOR NERN
AND CNTRL MO ON WED. THESE WARM CONDITIONS WILL CONTINUE WED NGT
AND THANKSGIVING DAY DUE TO INCREASING S-SWLY LOW LEVEL WINDS.
ALTHOUGH THE ECMWF AND GFS MODELS STILL HAVE DIFFERENCES FOR THU
AND FRI THERE SOLUTIONS HAVE BECOME MORE SIMILAR THAN THEY WERE
THE PAST COUPLE OF DAYS. IT APPEARS THAT THE GFS HAS SOME FEEDBACK
PROBLEMS WED NGT AND THU AND IS LIKELY BRINGING PRECIPITATION
INTO OUR AREA A LITTLE TOO EARLY ON THU. PREFER THE ECMWF MODEL
WHICH HAS MOST OF THE PRECIPITATION THU NGT AS AN UPPER LEVEL LOW
MOVES SEWD THROUGH THE NRN PLAINS SENDING A STRONG COLD FRONT
SEWD THROUGH OUR AREA THU NGT. THE GFS IS NOW COLDER THAN THE
ECMWF MODEL THU NGT INTO FRI MRNG AND BRINGS THE ZERO DEGREE C
850 MB ISOTHERM SEWD TO STL BY 12Z FRI. THE ECMWF MODEL THOUGH IS
A LITTLE SLOWER AND DEEPER WITH THE UPPER LEVEL LOW MOVING THROUGH
THE NRN PORTION OF THE GREAT LAKES REGION ON FRI AND BRINGS
COLDER AIR INTO OUR REGION FRI AFTN THAN THE GFS. WILL TREND
COLDER WITH TEMPERATURES FRI AND FRI NGT ALTHOUGH NOT AS COLD AS
THE ECMWF MODEL WOULD IMPLY. A WARMING TREND WILL BEGIN ON SAT OR
SAT NGT ALTHOUGH WILL TRY TO FOLLOW THE SLOWER WARMING OF THE
ECMWF MODEL. NEXT CHANCE OF PRECIPITATION SHOULD HOLD OFF TIL SUN
NGT AS A STORM SYSTEM TAKES SHAPE OVER THE SRN PLAINS.
GKS
&&
.AVIATION...
ISSUED AT 524 AM CST MON NOV 19 2012
AREA OF RAIN OVER MO WILL CONTINUE TO MOVE NORTHEAST THE NEXT FEW
HOURS...BUT IS EXPECTED TO GRADUALLY DECREASE IN AREAL COVERAGE.
THERE ARE A FEW LOCATIONS WITH MVFR CIGS WITHIN THE AREA OF RAIN
OVER SWRN MO...BUT MOST LOCATIONS ARE REPORTING VFR SO WILL GO
WITH A FEW HOURS OF VFR -RA AT KCOU AND KUIN THIS MORNING. THE
AREAL EXTENT OF THE RAIN IS EXPECTED TO DIMINISH ENOUGH TO NOT
INCLUDE IN THE STL METRO TAF SITES. MID LEVEL CIGS ARE EXPECTED TO
SLOWLY FALL DURING THE DAY...BUT THE CLEARING LINE WILL MOVE INTO
KCOU OVERNIGHT AND AT KUIN AND STL METRO TAF SITES AFTER 12Z
TUESDAY. THERE MAY BE AREAS OF FOG DEVELOP AFTER 09Z TONIGHT AS
WINDS BECOME LIGHT AHEAD OF AN APPROACHING COLD FRONT.
SPECIFICS FOR KSTL...WHILE THERE IS A SLIGHT CHANCE FOR THE -RA
OVER CENTRAL MO TO MAKE IT INTO THE TERMINAL LATER THIS MORNING/
AFTERNOON...I DO NOT THINK THE CHANCE IS HIGH ENOUGH TO INCLUDE IN
THE TAF AT THIS POINT. OTHERWISE...EXPECT MAINLY DRY AND VFR
CONDITIONS THROUGH THE PERIOD.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1111 PM CST Sun Nov 18 2012
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
Tonight - Monday:
The main challenges through this period are the timing/onset of
precipitation and the duration into the Monday period. Water vapor
imagery was showing the weak upper level disturbance moving out of
the Southern Rockies and into the Plains. Radar and visible/IR
imagery show what also may be a weak baroclinic zone across south
central to eastern Nebraska with a few light returns showing up on
radar. The GFS does indicate a slightly tighter theta-e gradient
aloft through this area. The radar returns are consistent with the
latest HRRR run, albeit a few hours delayed, which develops
precipitation in this area this afternoon. Precipitation should
increase in coverage across the eastern half of Kansas this evening
as the support from the upper wave moves into the region. Think that
the timing of precipitation in our western zones will be in the 2-3Z
window and persist for 4-6 hours as the whole area moves into our
eastern zones. It still looks like coverage will be in the 50% range
and precipitation totals will be less than a quarter inch for those
that do pick up rain. Precipitation still looks to be coming to end
by mid day Monday. There could potentially be a few sprinkles Monday
afternoon as another weak wave will be tracking into the area. But
models are in good agreement moving any QPF away from the area
during the afternoon so the chances of precipitation look too small
to mention at this time.
High temperatures on Monday will be restrained a bit in our eastern
zones as cloud cover will be exiting the area preventing a warm up
like our western zones are expected to see. Overall, highs will
range from the low to mid 60s in our west to the middle 50s in our
east.
Tuesday - Tuesday Night:
Quiet weather with above normal temperatures are expected this
period. High temperatures should climb into the 60s across the area
but may be inhibited by weak flow and limited mixing. Overnight lows
should be mild for this time of year with lows generally in the low
to mid 40s. With light winds overnight, some of our typical low
lying/ drainage areas may fall into the 30s.
CDB
Wednesday - Sunday:
Model consensus is a continuation of near to above average
temperatures during this period with little in the way of
precipitation. Travel day on Wednesday looks outstanding with
temperatures nearing the 70 degree mark possible in the far western
CWA.
Most of the focus is on Thursday/Thanksgiving. An upper level ridge
will exit the region on Wednesday as another impulse within the
southern stream lifts northeast from the Southern Rockies on
Thanksgiving. Despite a lack of low level moisture there is
increasing support from the GFS and ECMWF that sufficient mid level
Pacific moisture will be available for scattered light showers as a
weak cold front drops southeast through MO Thursday night. Have
nudged Thursday night pops up to chance category for the far
southern counties.
A large vortex over the Gulf of Alaska is expected to eject a
significant piece of energy eastward at the start of the period. The
resulting shortwave trough will dig/deepen southeast through the
Upper MS Valley and Great Lakes Thursday night/Friday. Any weather
with this feature will track to the north but a secondary cold front
will pass through on Friday and reinforce an intrusion of colder
air. Have gone along with model consensus on temperatures but the
trend is towards more cooling and can envision later forecasts
tweaking Friday`s temperatures downward some more.
Zonal flow through the mid levels and warm air advection in the
boundary layer will return for the dry weekend.
MJ
&&
.AVIATION...
As the upper disturbance moves through overnight, I expect the area
of precipitation over southeast Kansas to spread northeast. Out of
the three TAF sights, precipitation chances will be greatest at MKC,
less at MCI, and low enough not to mention at STJ. Still looks like
precipitation will end prior to sunrise. Expect VFR conditions to
prevail even in the light rain.
Bailey
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1056 PM CST SUN NOV 18 2012
.AVIATION...06Z KGRI TAF. VFR CONDITIONS WILL CONTINUE AT THE
TERMINAL FOR THE NEXT 24 HOURS. EXPECT WINDS TO BECOME LIGHT AND
VARIABLE OVERNIGHT AS A SURFACE TROUGH TO THE WEST NUDGES
EASTWARD. AS THIS TROUGH SHIFTS FURTHER EAST DURING THE DAY ON
MONDAY...WINDS WILL EVENTUALLY BECOME WEST TO NORTHWESTERLY AFT
ABOUT 19/13Z. OTHER THAN THIS WIND SHIFT...CLEAR SKIES AND NO
VISIBILITY OBSTRUCTIONS ARE EXPECTED.
&&
.PREV DISCUSSION... /ISSUED 305 PM CST SUN NOV 18 2012/
SHORT TERM...THROUGH MONDAY AFTERNOON. OVERALL THE BENIGN WEATHER
PATTERN OF LATE CONTINUES THROUGH THE NEXT 24 HOURS...WITH THE
MAIN FAIRLY MINOR ISSUE CONSISTING OF THE POSSIBILITY OF SPRINKLES
ACROSS SOUTHEAST ZONES LATE THIS AFTERNOON INTO THIS EVENING.
20Z OBJECTIVE SURFACE ANALYSIS PLACES A GENERALLY NORTH-SOUTH
TROUGH AXIS RUNNING FROM WESTERN SD THROUGH THE NEB PANHANDLE AND
DOWN ALONG THE KS/CO BORDER...TRAILING SOUTH FROM A 1005MB LOW AT
THE WY/MT/SD INTERSECTION. MEANWHILE...AN EXPANSIVE RIDGE AXIS
CONTINUES TO DOMINATE MUCH OF THE EASTERN CONUS. THE CWA LIES
ALONG THE INTERFACE BETWEEN THESE TWO FEATURES...WITH A MODEST
PRESSURE GRADIENT AND DIURNAL MIXING GENERALLY INTO THE 900-875MB
RANGE DRIVING SOUTHERLY SUSTAINED BREEZES TYPICALLY 13-23 MPH WITH
GUSTS MAINLY 20-25 MPH. VISIBLE SATELLITE CONFIRMS A RATHER
HEALTHY COVERAGE OF MID-HIGH CLOUDS STREAMING
OVERHEAD...ESPECIALLY ACROSS THE SOUTHEAST 2/3 OF THE CWA. RADAR
EVEN SUGGESTS A FEW SPRINKLES MAY HAVE ALREADY FALLEN THIS
AFTERNOON ACROSS PARTS OF NUCKOLLS/THAYER/FILLMORE COUNTIES. THESE
CLOUDS SEEM TO BE HAVING A VARYING EFFECT ON TEMPS THIS
AFTERNOON...WITH BOTH KS ZONES AND NORTHERN ZONES IN NEB VERY MUCH
ON TRACK TO NEAR FORECAST HIGHS IN THE LOW-MID 60S...WHILE CENTRAL
AREAS INCLUDING THE TRI-CITIES MAY FALL A BIT SHORT AND STRUGGLE
TO REACH 60. THE CLOUDS HAVE LIKELY ALSO REDUCED MIXING SOMEWHAT
AND HELD DOWN WIND SPEEDS SLIGHTLY. WATER VAPOR IMAGERY AND SHORT
TERM MODEL DATA DEPICTS BROAD QUASI-ZONAL/SLIGHTLY SOUTHWESTERLY
FLOW ACROSS THE CENTRAL/WESTERN CONUS...WITH A PAIR OF FAIRLY
VIGOROUS SHORTWAVE TROUGHS TRANSLATING THROUGH THE NORTHERN
ROCKIES AND OFF THE PACIFIC NORTHWEST COAST. CLOSER TO HOME...A
MORE SUBTLE LOW AMPLITUDE MID LEVEL WAVE IS CURRENTLY LIFTING OUT
OF CO/WY...INTO NEB/KS...WITH THE MID-HIGH CLOUDS STREAMING OUT
AHEAD OF THIS WAVE LARGELY ASSOCIATED WITH A MODEST 70+KT 300MB
JET STREAK.
LATE THIS AFTERNOON INTO THIS EVENING...THIS LOW AMPLITUDE MID
LEVEL WAVE WILL CONTINUE TRACKING ACROSS THE HEART OF THE CENTRAL
PLAINS...WITH THE ONGOING BATCH OF MID-HIGH CLOUDS GRADUALLY
CLEARING THE CWA FROM WEST-EAST AND PAVING THE WAY FOR A CLEAR
OVERNIGHT. PRIOR TO THIS HOWEVER...THE MOISTURE-STARVED
DISTURBANCE WILL CONTINUE TO PROMOTE MODEST THETA-E ADVECTION
EVIDENT IN THE 850-700MB LAYER MAINLY OVER THE EASTERN HALVES OF
NEB/KS. DESPITE PLENTIFUL DRY AIR ESPECIALLY BELOW 700MB...WILL
MAINTAIN A CHANCE OF SPRINKLES THROUGH 10 PM FOR LOCATIONS
GENERALLY EAST OF A LINE FROM YORK-NELSON-OSBORNE...WITH
ESSENTIALLY ZERO RISK OF PRECIP ACROSS THE REMAINDER OF THE CWA.
DESPITE VARIOUS MODELS SUCH AS THE NAM/ECMWF/GFS KEEPING ALL QPF
EAST OF THE CWA INTO THIS EVENING...THE WEAK RADAR RETURNS ALREADY
OBSERVED WITHIN THE FAR SOUTHEAST CWA THIS AFTERNOON ALONG WITH
THE 1KM REFLECTIVITY PROGS FROM THE LATEST HRRR MAKE ME UNWILLING
TO COMPLETELY IGNORE SPRINKLE POTENTIAL...ALTHOUGH AGREE WITH
PREVIOUS FORECASTER THAT ANYTHING MEASURABLE SHOULD FOCUS WELL
EAST/SOUTHEAST OF THE LOCAL AREA. AS MENTIONED...THE OVERNIGHT
WILL FEATURE CLEAR SKIES...WHILE AT THE SURFACE...A WEAK TROUGH
WILL MOVE EASTWARD ACROSS MAINLY THE WESTERN 1/2 OF THE
CWA...TURNING LIGHT BREEZES NORTHWESTERLY IN ITS WAKE. TEMPS
OVERNIGHT COULD BE A BIT TRICKY...AS THE NORTHWEST COMPONENT
BEHIND THE SURFACE TROUGH COULD ACT TO HOLD THINGS UP...WHILE JUST
AHEAD OF THE TROUGH THE COMBINATION OF NEAR-CALM TO LIGHT
SOUTHERLY BREEZES AND CLEAR SKIES SHOULD PROMOTE AN EFFICIENT
DROP. FEEL THAT A BLEND OF 12Z MET/MAV GUIDANCE IS PROBABLY THE
BEST COMPROMISE...AND THUS WILL LOWER MOST OF THE CWA 2-3 DEGREES
FROM PREVIOUS FORECAST...BUT STILL KEEPING ALL BUT A FEW NORTHWEST
COUNTIES ABOVE FREEZING AND IN THE 33-37 RANGE. ALTHOUGH SUPPOSE
SOME HAZE OR LIGHT FOG IS NOT OUT OF THE QUESTION AROUND SUNRISE
ESPECIALLY ALONG THE TROUGH AXIS...AM NOT EXPECTING FOG TO BE
WORTHY OF A FORMAL MENTION IN THE FORECAST.
FOR THE MONDAY DAYTIME PERIOD...TRANQUIL...MOISTURE-STARVED QUASI-
ZONAL FLOW WILL CONTINUE ALOFT OVER THE CENTRAL PLAINS...AS THE
SHORTWAVE CURRENTLY AFFECTING THE AREA MOVES WELL OFF EAST TOWARD
THE GREAT LAKES...WHILE THE SOUTHERN FRINGES OF ANOTHER MID LEVEL
WAVE CENTERED OVER THE CANADIAN BORDER BRUSHES INTO WESTERN NEB
DURING THE AFTERNOON. WHILE THE MAJORITY OF THE DAY SHOULD REMAIN
QUITE SUNNY WITH ONLY A FEW PASSING SPLOTCHES OF HIGH CIRRUS...THE
MID-LATE AFTERNOON HOURS COULD FEATURE A BIT GREATER INCOMING
CIRRUS COVERAGE MAINLY OVER NORTHWEST ZONES ASSOCIATED WITH THE
APPROACHING SHORTWAVE TROUGH. AT THE SURFACE...THE TROUGH AXIS
ESSENTIALLY BISECTING THE AREA AT SUNRISE WILL CONTINUE PUSHING
SOUTHEAST THROUGH THE DAY. IN ITS WAKE...FAIRLY LIGHT BREEZES OF
ONLY AROUND 10 MPH FROM THE NORTH-NORTHWEST WILL PREVAIL. THESE
LIGHT WINDS WILL MAKE FOR PLEASANT CONDITIONS THANKS TO THE NEXT
IN A LONG STRETCH OF SEASONABLY WARM DAYS. MADE VERY LITTLE
CHANGE TO HIGH TEMPS...AND IF ANYTHING NUDGED SOME PLACES UP
ANOTHER DEGREE...AIMING FOR LOW 60S NORTHEAST...MID 60S CENTRAL
INCLUDING TRI-CITIES...AND UPPER 60S KS ZONES. THE OVERALL BIGGEST
CHANGE TO THE MONDAY GRIDS WAS TO DEWPOINTS...WHICH WERE LOWERED
4-7 DEGREES...WITH VALUES ONLY EXPECTED TO AVERAGE IN THE LOW-MID
30S IN MOST AREAS. EVEN SO...RELATIVE HUMIDITY VALUES SHOULD STILL
DROP NO LOWER THAN THE UPPER 20S...KEEPING FIRE DANGER QUITE LOW
THANKS TO THE LIGHT WINDS.
LONG TERM...STARTING 00Z TUESDAY. GUIDANCE FROM THE
OPERATIONAL GFS...GEFS-MEAN AND EC ALL CONTINUE TO SUGGEST MID
AND UPPER LEVEL JET ENERGY WILL REMAIN TO THE NORTH OF THE CENTRAL
PLAINS THROUGH THE LONG TERM FORECAST PERIOD. A MID LEVEL SHORT
WAVE IS EXPECTED TO PUSH ACROSS SOUTHERN CANADA AND THE NORTHERN
PLAINS DURING THE DAY THURSDAY...ALONG WITH A WEAK MID LEVEL
PERTURBATION WHICH IS EXPECTED PUSH ACROSS THE SOUTHERN PLAINS
ALSO ON THURSDAY. ALTHOUGH THESE MID LEVEL DISTURBANCES WILL
REMAIN NORTH AND SOUTH OF OUR REGION...AN ASSOCIATED LOW LEVEL
BAROCLINIC ZONE IS EXPECTED TO PUSH ACROSS OUR AREA DURING THE DAY
THURSDAY. THE OPERATIONAL GFS AND EC BOTH CONTINUE TO SUGGEST LOW
LEVEL CONVERGENCE AND RESULTANT FORCING WILL REMAIN WEAK ALONG
THIS BAROCLINIC ZONE. ALTHOUGH THERE COULD BE AN INCREASE IN MID
TO HIGH LEVEL CLOUDS AS THE MID LEVEL PERTURBATION PUSHES ACROSS
THE SOUTHERN PLAINS...AN OVERALL LACK IN KINEMATIC FORCING SHOULD
KEEP OUR AREA DRY THROUGHOUT THE LONG TERM FORECAST PERIOD.
LITTLE CHANGE IN THE LOW LEVEL AIRMASS TUESDAY THROUGH THURSDAY WILL
PRESENT SIMILAR TEMPERATURES EACH DAY...WITH HIGHS GENERALLY IN THE
60S AND LOWS IN THE 30S AND 40S...WHICH IS WELL ABOVE NORMAL FOR
THIS TIME OF YEAR. WEAK LOW LEVEL COLD AIR ADVECTION POST FROPA
BEGINNING THURSDAY NIGHT WILL THEN PRESENT SOMEWHAT COOLER WEATHER
TO FINISH OUT THE WEEK...WITH HIGHS GENERALLY IN THE 50S AND LOWS IN
THE 30S...STILL ABOVE NORMAL FOR THIS TIME OF YEAR.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM...BRYANT
AVIATION...ROSSI
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
613 PM EST TUE NOV 20 2012
.SYNOPSIS...
A WEAKENING COLD FRONT OVER NORTHWEST OHIO WILL DISSIPATE AS IT
MOVES ACROSS THE LOCAL AREA TONIGHT. HIGH PRESSURE WILL RETURN
FOR WEDNESDAY AND THE THANKSGIVING HOLIDAY. A STRONGER COLD FRONT
IS EXPECTED TO ARRIVE ON FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
RADAR CONTINUES TO SHOW SOME WEAK RETURNS WITH A LEGITIMATE SHOWER
OVER RICHLAND COUNTY. A FEW SHOWERS HAVE COME AND GONE THE PAST
HOUR OR SO. WILL GO WITH A 20 POP OVER MUCH OF THE AREA THROUGH
00Z OR SO TO COVER ANY NEW DEVELOPMENT. LATEST HRRR INDICATES THAT
THIS IS A REASONABLE SCENARIO. WHAT IS LEFT OF THE COLD FRONT HAS
MOVED INTO NW OH AND SHOULD BE COMPLETELY GONE BY LATE EVENING.
HAVE SEEN SOME BREAKS IN THE CLOUDS RECENTLY BUT THINK THE FLAVOR
OF THE NIGHT WILL BE MOSTLY CLOUDY AS STRATO CU BEHIND THE FRONT
MOVES INTO THE AREA. GUIDANCE TEMPS LOOK REASONABLE.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY NIGHT/...
WE SHOULD SEE A DECREASE IN THE CLOUDS TOMORROW WITH PARTLY
CLOUDY TO MOSTLY SUNNY SKIES BY LATE AFTERNOON. TEMPS WILL BE A
DEGREE OR TWO WARMER THAN TODAY GIVEN THE SUNSHINE. EVEN WARMER
READINGS ARE EXPECTED FOR THANKSGIVING AS THE RIDGE AXIS WILL BE
JUST EAST OF THE AREA. ABUNDANT SUNSHINE IS ALSO EXPECTED. THE
MODELS CONTINUE TO BE IN DECENT AGREEMENT WITH THE COLD FRONTAL
PASSAGE ON FRIDAY. THE FRONT SHOULD BE INTO NW PA BY EARLY
AFTERNOON. ALL OF THE NEW GUIDANCE IS SHOWING A LINE OF SHOWERS
ALONG THE FRONT AND HAVE BUMPED POPS UP SLIGHTLY. EXPECT THAT
LATER SHIFTS MAY EVENTUALLY NEED TO GO WITH LIKELY OR HIGHER
WORDING. GOOD COLD AIR ADVECTION IS EXPECTED BEHIND THE FRONT WITH
850 MB TEMPS DIPPING TO AROUND NEG 10 BY 12Z SAT. WILL NEED TO HANG
ON TO SOME LAKE EFFECT PRECIP FRIDAY NIGHT OVER MOST OF THE AREA.
HAVE USED A BLEND OF GUIDANCE TEMPS DURING THE PERIOD.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
A DECENT LAKE EFFECT SHSN EVENT STILL LOOKS IN ORDER FOR SAT INTO
SAT NIGHT TAPERING TO MAINLY FLURRIES BY SUN MORNING AS RIDGE OF
HIGH PRESSURE MOVES OVERHEAD. THE RIDGE SHOULD BRIEFLY STOP THE
PRECIP THEN ANOTHER SYSTEM IS EXPECTED TO APPROACH THE AREA WITH
MOISTURE ARRIVING MONDAY. THE MODELS DIFFER GREATLY BY TUE SO WILL
CONTINUE A SMALL CHANCE FOR RAIN OR SNOW INTO TUE THUS LEANING MORE
TOWARD THE ECMWF AS THE GFS LOOKS TO BE TRENDING MORE THAT WAY TOO.
&&
.AVIATION /22Z TUESDAY THROUGH SUNDAY/...
VFR WILL CONTINUE FOR THE EVENING PUSH WITH MID LEVEL DECK. COULD
SEE A FEW SPRINKLES TONIGHT WITH WEAKENING FRONT/TROUGH...BUT
LITTLE MORE. EXPECT SOME PATCHY MVFR FOG TO DEVELOP AT SOME TAF
SITES LATE TONIGHT. WINDS WILL STAY LIGHT AND VARIABLE. CLOUDS
WILL GRADUALLY SCATTER OUT FROM THE WEST LATE WEDNESDAY AS HIGH
PRESSURE BUILDS OVER THE AREA.
OUTLOOK...NON-VFR SHOULD OCCUR FRIDAY INTO SATURDAY NIGHT. SHRA
WILL DEVELOP FRIDAY WITH A STRONG COLD FRONT. RAIN WILL CHANGE TO
SNOW LATE FRIDAY NIGHT AND LINGER INTO SATURDAY NIGHT FOR THE
SNOWBELT. VFR SHOULD RETURN TO MOST SITES SUNDAY.
&&
.MARINE...
A RIDGE ACROSS THE LAKE WILL SHIFT SOUTHEAST LATE WEDNESDAY AND THAT
WILL ALLOW A SOUTHWEST FLOW TO DEVELOP. THE SOUTHWEST FLOW WILL
CONTINUE TO INCREASE THROUGH THURSDAY NIGHT BUT WITH THE LAKE AND
850 MB TEMPERATURE DIFFERENCE NEAR 0C...STABLE...IT WILL BE TOUGH
FOR THOSE STRONGER WINDS TO GET TO THE LAKE SURFACE. A SMALL CRAFT
ADVISORY MAY BE NEEDED BY LATE THURSDAY NIGHT WITH WINDS OF 15 TO 25
KNOTS. GOING WITH THE SLOWER GFS/ECMWF SOLUTIONS WHICH HAS THE COLD
FRONTAL PASSAGE AND A LITTLE STRONGER WINDS FOR LATE FRIDAY. IT IS
POSSIBLE THAT WINDS COULD BE CLOSE TO GALE FORCE MAINLY ON THE EAST
END OF THE LAKE FRIDAY AFTERNOON. AT THIS TIME IT LOOKS VERY
MARGINAL AND BRIEF...THIS WILL HAVE TO BE MONITORED. THE WATER LEVEL
WILL ALSO HAVE TO BE WATCHED ON THE WEST END OF THE LAKE FRIDAY AND
FRIDAY NIGHT. NONE THE LESS A SMALL CRAFT ADVISORY WILL LIKELY BE
NEED FROM LATE THURSDAY NIGHT THROUGH EARLY SATURDAY NIGHT. LATE
SATURDAY NIGHT AND ON SUNDAY THE WINDS SHIFT TO THE SOUTHWEST AS A
RIDGE MOVES EAST OF THE LAKE. ANOTHER FRONT OR TROF WILL MOVE ACROSS
THE LAKE LATE SUNDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...KUBINA
SHORT TERM...KUBINA
LONG TERM...ADAMS
AVIATION...DJB
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
800 AM EST MON NOV 19 2012
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE OVER THE EASTERN UNITED STATES WILL
KEEP THE REGION FAIR AND DRY FOR MOST OF THIS WEEK. IN GENERAL...
SUNNY DAYS AND COOL NIGHTS ARE EXPECTED WITH SOME PATCHY FOG. MUCH
COLDER WEATHER IS EXPECTED BY NEXT WEEKEND AS A POOL OF COLD
CANADIAN AIR SPILLS ACROSS THE GREAT LAKES AND ACROSS THE
NORTHEASTERN UNITED STATES.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
UPDATE DONE TO COVER EXPANDING AREA OF LOWER CLDS. STILL EXPECT
THESE CLDS TO BREAK UP BY LATE MORNING.
EARLIER DISCUSSION BELOW.
LOW CLOUDS HAVE EXPANDED TO COVER MOST OF THE LAUREL HIGHLANDS AND
PORTIONS OF THE SOUTH CENTRAL MOUNTAINS THIS MORNING. PATCHY LOW
CLOUDS HAVE ALSO PROPOGATED INTO PARTS OF THE CENTRAL AND NORTHERN
MOUNTAINS AS WELL. THE EASTERLY FLOW AROUND THE CANADIAN MARITIME
STRONG SFC RIDGE CENTER AND LOW PRESSURE ORGANIZING ALONG THE
SOUTHEAST ATLANTIC COAST IS SHUNTING ENOUGH LOW LEVEL MOISTURE
WESTWARD AND UP AGAINST THE HIGHER TERRAIN OF SOUTH CENTRAL AND
CENTRAL PA IN THE PRESENCE OF WEAK VERTICAL MIXING TO PRODUCE THE
LOW CLOUDS. TEMPS UNDER THE STRATUS MODERATE TO THE LOWER TO
MIDDLE 30S...WHILE AREAS AWAY FROM THE STRATUS ARE IN THE UPPER
20S. PATCHY FOG IS ALSO PREVALENT IN THE CLEAR AREAS...WITH VSBYS
BETWEEN 3 AND 5 MILES THIS MORNING.
STRATO CU CLOUDS SHOULD PERSIST ACROSS THE CENT MTNS AND LAURELS
THROUGH LATE MORNING THE EASTERLY UPSLOPE FLOW OF LLVL MARINE AIR
CONTINUES. EARLY MORNING FOG WILL DECREASE BY MID MORNING...WHILE
THE STRATUS LARGELY DISSIPATES BY LATE MORNING. PARTLY TO MOSTLY
SUNNY SKIES WILL DEVELOP BY THE LATE MORNING NEAR AND TO THE EAST
OF A LINE FROM KIPT TO KSEG AND KMDT. HOWEVER...NAM12 OUTLIER
SOLUTION SHOWS STRATUS PERSISTING OVER THE LOWER SUSQ THROUGH THIS
AFTERNOON...WHILE LCL 3KM HRRR SHOWS DISSIPATING AFT 15Z. TEMPS
WILL HAVE TO BE WATCHED CLOSELY AS MORE EXPANSIVE AND PERSISTENT
LOW CLOUDS COULD HOLD DOWN MAXES ACROSS CENTRAL AND SOUTHWEST
PORTIONS OF CENTRAL PA.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM TUESDAY/...
EXPECT MORE OF THE SAME TONIGHT INTO TUESDAY MORNING WITH AT LEAST
A COMPONENT OF RETURN/UPSLOPE FLOW ACTING TO PRODUCE AREAS OF LOW
CLOUDS WITH TIES TO THE LAUREL HIGHLANDS AND SOUTH CENTRAL
MOUNTAINS. SFC RIDGE AXIS REMAINS ANCHORED OVER EASTERN THIRD OF
PENNSYLVANIA TONIGHT AND TUESDAY...AND IT APPEARS THE EASTERLY
ATLANTIC FETCH WILL BECOME MORE NE TO SW ORIENTED BY 12Z TUE...
SO EXTENT OF STRATUS IS EXPECTED TO BE FAR LESS ON TUESDAY MORNING
THAN THIS MORNING...BUT WITH THE TYPICAL RIVER VALLEY FOG THAT
ACCOMPANIES STABLE STRATIFICATION OVER CENTRAL AND EASTERN PA.
MINS TONIGHT SHOULD RANGE FROM THE MID TO UPPER 20S ACROSS THE
NORTH TO THE LOWER 30S OVER THE SOUTHEAST. GENERALLY STAYED A FEW
TICKS ABOVE MOS...WHICH MAY BE UNDERDOING THE EXTENT OF FOG AND
LOW CLOUDS EARLY TUESDAY MORNING. HIGHS SHOULD MODERATE TO THE 50S
EVERYWHERE TUESDAY AFTERNOON.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
EXPECT A DIGGING TROUGH TO MOVE THROUGH EARLY WEDNESDAY. THIS
WILL BRING SOME SLIGHT CLOUDINESS AND THE RETURN FLOW OF MOISTURE
AROUND THE RIDGE MAY ADVECT ENOUGH MOISTURE NORTHWARD UP THE SPINE
OF THE APPALACHIANS TO PRODUCE A LIGHT SHOWER OVER PARTS OF THE
REGION TUESDAY NIGHT. HOWEVER ANY DOWNSLOPING SHOULD REDUCE THIS
MOISTURE AND ANY PRECIPITATION REMAINS A LOW PROBABILITY. HAVE
CONTINUED TO REDUCE POPS ACCORDINGLY. EXPECT MILD AND DRY WEATHER
WITH WARMER THAN NORMAL TEMPERATURES THROUGH THE WORK WEEK...WITH
MAX TEMPERATURES 5 TO 10 DEGREES WARMER THAN NORMAL.
THE NEXT CHANCE FOR MEASURABLE PRECIPITATION WILL BE LATE THIS
COMING WEEK AS A DEEP TROUGH MOVES IN FROM THE NORTHWEST. THE
MODELS CONTINUE TO BRING DEEP COLD AIR IN BEHIND THE FRONT...WITH
-7C 850MB TEMPS POSSIBLE NEXT SATURDAY NIGHT. EXPECT TEMPERATURES
NEXT WEEKEND TO BE BELOW NORMAL...WITH RAIN SHOWERS POSSIBLE OUT
AHEAD OF THE FRONT...FOLLOWED BY A RIBBON OF MIXED
PRECIPITATION...AND SNOW SHOWERS BEHIND. THERE IS TO MUCH
VARIABILITY TO GIVE A GOOD QUANTIFICATION OF SNOW AMOUNTS.
HOWEVER...CURRENTLY ANY ACCUMULATIONS SEEM TO BE LIGHT. THE EC
CONTINUES TO SLOWS THE SYSTEM DOWN...ABOUT 12 HRS SLOWER THAN THE
GFS. HOWEVER BOTH MODELS HAVE A SIMILAR ORIENTATION..THOUGH THE EC
HAS A DEEPER LOW THAT IS FURTHER SOUTH.
&&
.AVIATION /13Z MONDAY THROUGH FRIDAY/...
ADJUSTED 12Z TAFS FOR EXPANDING AREA OF LOWER CLDS. STILL
EXPECT THESE CLDS TO BREAK UP BY LATE MORNING.
OTHERWISE...HIGH PRESSURE ACROSS EASTERN CANADA AND THE NEW
ENGLAND STATES WILL REMAIN NEARLY STATIONY FOR THE NEXT FEW
DAYS...BRINGING MAINLY CLEAR SKIES TO THE AREA.
OUTLOOK...
WED...PATCHY AM VALLEY FOG POSSIBLE ACROSS THE ALLEGHENIES.
THU-FRI...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...DANGELO/MARTIN
SHORT TERM...DEVOIR/LAMBERT
LONG TERM...DEVOIR/CERU
AVIATION...FITZGERALD/MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
647 AM EST MON NOV 19 2012
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE OVER THE EASTERN UNITED STATES WILL
KEEP THE REGION FAIR AND DRY FOR MOST OF THIS WEEK. IN GENERAL...
SUNNY DAYS AND COOL NIGHTS ARE EXPECTED WITH SOME PATCHY FOG. MUCH
COLDER WEATHER IS EXPECTED BY NEXT WEEKEND AS A POOL OF COLD
CANADIAN AIR SPILLS ACROSS THE GREAT LAKES AND ACROSS THE
NORTHEASTERN UNITED STATES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATE DONE TO COVER EXPANDING AREA OF LOWER CLDS. STILL EXPECT
THESE CLDS TO BREAK UP BY LATE MORNING.
EARLIER DISCUSSION BELOW.
LOW CLOUDS HAVE EXPANDED TO COVER MOST OF THE LAUREL HIGHLANDS AND
PORTIONS OF THE SOUTH CENTRAL MOUNTAINS THIS MORNING. PATCHY LOW
CLOUDS HAVE ALSO PROPOGATED INTO PARTS OF THE CENTRAL AND NORTHERN
MOUNTAINS AS WELL. THE EASTERLY FLOW AROUND THE CANADIAN MARITIME
STRONG SFC RIDGE CENTER AND LOW PRESSURE ORGANIZING ALONG THE
SOUTHEAST ATLANTIC COAST IS SHUNTING ENOUGH LOW LEVEL MOISTURE
WESTWARD AND UP AGAINST THE HIGHER TERRAIN OF SOUTH CENTRAL AND
CENTRAL PA IN THE PRESENCE OF WEAK VERTICAL MIXING TO PRODUCE THE
LOW CLOUDS. TEMPS UNDER THE STRATUS MODERATE TO THE LOWER TO
MIDDLE 30S...WHILE AREAS AWAY FROM THE STRATUS ARE IN THE UPPER
20S. PATCHY FOG IS ALSO PREVALENT IN THE CLEAR AREAS...WITH VSBYS
BETWEEN 3 AND 5 MILES THIS MORNING.
STRATO CU CLOUDS SHOULD PERSIST ACROSS THE CENT MTNS AND LAURELS
THROUGH LATE MORNING THE EASTERLY UPSLOPE FLOW OF LLVL MARINE AIR
CONTINUES. EARLY MORNING FOG WILL DECREASE BY MID MORNING...WHILE
THE STRATUS LARGELY DISSIPATES BY LATE MORNING. PARTLY TO MOSTLY
SUNNY SKIES WILL DEVELOP BY THE LATE MORNING NEAR AND TO THE EAST
OF A LINE FROM KIPT TO KSEG AND KMDT. HOWEVER...NAM12 OUTLIER
SOLUTION SHOWS STRATUS PERSISTING OVER THE LOWER SUSQ THROUGH THIS
AFTERNOON...WHILE LCL 3KM HRRR SHOWS DISSIPATING AFT 15Z. TEMPS
WILL HAVE TO BE WATCHED CLOSELY AS MORE EXPANSIVE AND PERSISTENT
LOW CLOUDS COULD HOLD DOWN MAXES ACROSS CENTRAL AND SOUTHWEST
PORTIONS OF CENTRAL PA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
EXPECT MORE OF THE SAME TONIGHT INTO TUESDAY MORNING WITH AT LEAST
A COMPONENT OF RETURN/UPSLOPE FLOW ACTING TO PRODUCE AREAS OF LOW
CLOUDS WITH TIES TO THE LAUREL HIGHLANDS AND SOUTH CENTRAL
MOUNTAINS. SFC RIDGE AXIS REMAINS ANCHORED OVER EASTERN THIRD OF
PENNSYLVANIA TONIGHT AND TUESDAY...AND IT APPEARS THE EASTERLY
ATLANTIC FETCH WILL BECOME MORE NE TO SW ORIENTED BY 12Z TUE...
SO EXTENT OF STRATUS IS EXPECTED TO BE FAR LESS ON TUESDAY MORNING
THAN THIS MORNING...BUT WITH THE TYPICAL RIVER VALLEY FOG THAT
ACCOMPANIES STABLE STRATIFICATION OVER CENTRAL AND EASTERN PA.
MINS TONIGHT SHOULD RANGE FROM THE MID TO UPPER 20S ACROSS THE
NORTH TO THE LOWER 30S OVER THE SOUTHEAST. GENERALLY STAYED A FEW
TICKS ABOVE MOS...WHICH MAY BE UNDERDOING THE EXTENT OF FOG AND
LOW CLOUDS EARLY TUESDAY MORNING. HIGHS SHOULD MODERATE TO THE 50S
EVERYWHERE TUESDAY AFTERNOON.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
EXPECT A DIGGING TROUGH TO MOVE THROUGH EARLY WEDNESDAY. THIS
WILL BRING SOME SLIGHT CLOUDINESS AND THE RETURN FLOW OF MOISTURE
AROUND THE RIDGE MAY ADVECT ENOUGH MOISTURE NORTHWARD UP THE SPINE
OF THE APPALACHIANS TO PRODUCE A LIGHT SHOWER OVER PARTS OF THE
REGION TUESDAY NIGHT. HOWEVER ANY DOWNSLOPING SHOULD REDUCE THIS
MOISTURE AND ANY PRECIPITATION REMAINS A LOW PROBABILITY. HAVE
CONTINUED TO REDUCE POPS ACCORDINGLY. EXPECT MILD AND DRY WEATHER
WITH WARMER THAN NORMAL TEMPERATURES THROUGH THE WORK WEEK...WITH
MAX TEMPERATURES 5 TO 10 DEGREES WARMER THAN NORMAL.
THE NEXT CHANCE FOR MEASURABLE PRECIPITATION WILL BE LATE THIS
COMING WEEK AS A DEEP TROUGH MOVES IN FROM THE NORTHWEST. THE
MODELS CONTINUE TO BRING DEEP COLD AIR IN BEHIND THE FRONT...WITH
-7C 850MB TEMPS POSSIBLE NEXT SATURDAY NIGHT. EXPECT TEMPERATURES
NEXT WEEKEND TO BE BELOW NORMAL...WITH RAIN SHOWERS POSSIBLE OUT
AHEAD OF THE FRONT...FOLLOWED BY A RIBBON OF MIXED
PRECIPITATION...AND SNOW SHOWERS BEHIND. THERE IS TO MUCH
VARIABILITY TO GIVE A GOOD QUANTIFICATION OF SNOW AMOUNTS.
HOWEVER...CURRENTLY ANY ACCUMULATIONS SEEM TO BE LIGHT. THE EC
CONTINUES TO SLOWS THE SYSTEM DOWN...ABOUT 12 HRS SLOWER THAN THE
GFS. HOWEVER BOTH MODELS HAVE A SIMILAR ORIENTATION..THOUGH THE EC
HAS A DEEPER LOW THAT IS FURTHER SOUTH.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
ADJUSTED 12Z TAFS FOR EXPANDING AREA OF LOWER CLDS. STILL
EXPECT THESE CLDS TO BREAK UP BY LATE MORNING.
OTHERWISE...HIGH PRESSURE ACROSS EASTERN CANADA AND THE NEW
ENGLAND STATES WILL REMAIN NEARLY STATIONY FOR THE NEXT FEW
DAYS...BRINGING MAINLY CLEAR SKIES TO THE AREA.
OUTLOOK...
WED...PATCHY AM VALLEY FOG POSSIBLE ACROSS THE ALLEGHENIES.
THU-FRI...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...DEVOIR/LAMBERT/MARTIN
SHORT TERM...DEVOIR/LAMBERT
LONG TERM...DEVOIR/CERU
AVIATION...FITZGERALD/MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
437 AM EST MON NOV 19 2012
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE OVER THE EASTERN UNITED STATES WILL
KEEP THE REGION FAIR AND DRY FOR MOST OF THIS WEEK. IN GENERAL...
SUNNY DAYS AND COOL NIGHTS ARE EXPECTED WITH SOME PATCHY FOG. MUCH
COLDER WEATHER IS EXPECTED BY NEXT WEEKEND AS A POOL OF COLD
CANADIAN AIR SPILLS ACROSS THE GREAT LAKES AND ACROSS THE
NORTHEASTERN UNITED STATES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW CLOUDS HAVE EXPANDED TO COVER MOST OF THE LAUREL HIGHLANDS AND
PORTIONS OF THE SOUTH CENTRAL MOUNTAINS THIS MORNING. PATCHY LOW
CLOUDS HAVE ALSO PROPOGATED INTO PARTS OF THE CENTRAL AND NORTHERN
MOUNTAINS AS WELL. THE EASTERLY FLOW AROUND THE CANADIAN MARITIME
STRONG SFC RIDGE CENTER AND LOW PRESSURE ORGANIZING ALONG THE
SOUTHEAST ATLANTIC COAST IS SHUNTING ENOUGH LOW LEVEL MOISTURE
WESTWARD AND UP AGAINST THE HIGHER TERRAIN OF SOUTH CENTRAL AND
CENTRAL PA IN THE PRESENCE OF WEAK VERTICAL MIXING TO PRODUCE THE
LOW CLOUDS. TEMPS UNDER THE STRATUS MODERATE TO THE LOWER TO
MIDDLE 30S...WHILE AREAS AWAY FROM THE STRATUS ARE IN THE UPPER
20S. PATCHY FOG IS ALSO PREVALENT IN THE CLEAR AREAS...WITH VSBYS
BETWEEN 3 AND 5 MILES THIS MORNING.
STRATO CU CLOUDS SHOULD PERSIST ACROSS THE CENT MTNS AND LAURELS
THROUGH LATE MORNING THE EASTERLY UPSLOPE FLOW OF LLVL MARINE AIR
CONTINUES. EARLY MORNING FOG WILL DECREASE BY MID MORNING...WHILE
THE STRATUS LARGELY DISSIPATES BY LATE MORNING. PARTLY TO MOSTLY
SUNNY SKIES WILL DEVELOP BY THE LATE MORNING NEAR AND TO THE EAST
OF A LINE FROM KIPT TO KSEG AND KMDT. HOWEVER...NAM12 OUTLIER
SOLUTION SHOWS STRATUS PERSISTING OVER THE LOWER SUSQ THROUGH THIS
AFTERNOON...WHILE LCL 3KM HRRR SHOWS DISSIPATING AFT 15Z. TEMPS
WILL HAVE TO BE WATCHED CLOSELY AS MORE EXPANSIVE AND PERSISTENT
LOW CLOUDS COULD HOLD DOWN MAXES ACROSS CENTRAL AND SOUTHWEST
PORTIONS OF CENTRAL PA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
EXPECT MORE OF THE SAME TONIGHT INTO TUESDAY MORNING WITH AT LEAST
A COMPONENT OF RETURN/UPSLOPE FLOW ACTING TO PRODUCE AREAS OF LOW
CLOUDS WITH TIES TO THE LAUREL HIGHLANDS AND SOUTH CENTRAL
MOUNTAINS. SFC RIDGE AXIS REMAINS ANCHORED OVER EASTERN THIRD OF
PENNSYLVANIA TONIGHT AND TUESDAY...AND IT APPEARS THE EASTERLY
ATLANTIC FETCH WILL BECOME MORE NE TO SW ORIENTED BY 12Z TUE...
SO EXTENT OF STRATUS IS EXPECTED TO BE FAR LESS ON TUESDAY MORNING
THAN THIS MORNING...BUT WITH THE TYPICAL RIVER VALLEY FOG THAT
ACCOMPANIES STABLE STRATIFICATION OVER CENTRAL AND EASTERN PA.
MINS TONIGHT SHOULD RANGE FROM THE MID TO UPPER 20S ACROSS THE
NORTH TO THE LOWER 30S OVER THE SOUTHEAST. GENERALLY STAYED A FEW
TICKS ABOVE MOS...WHICH MAY BE UNDERDOING THE EXTENT OF FOG AND
LOW CLOUDS EARLY TUESDAY MORNING. HIGHS SHOULD MODERATE TO THE 50S
EVERYWHERE TUESDAY AFTERNOON.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
EXPECT A DIGGING TROUGH TO MOVE THROUGH EARLY WEDNESDAY. THIS
WILL BRING SOME SLIGHT CLOUDINESS AND THE RETURN FLOW OF MOISTURE
AROUND THE RIDGE MAY ADVECT ENOUGH MOISTURE NORTHWARD UP THE SPINE
OF THE APPALACHIANS TO PRODUCE A LIGHT SHOWER OVER PARTS OF THE
REGION TUESDAY NIGHT. HOWEVER ANY DOWNSLOPING SHOULD REDUCE THIS
MOISTURE AND ANY PRECIPITATION REMAINS A LOW PROBABILITY. HAVE
CONTINUED TO REDUCE POPS ACCORDINGLY. EXPECT MILD AND DRY WEATHER
WITH WARMER THAN NORMAL TEMPERATURES THROUGH THE WORK WEEK...WITH
MAX TEMPERATURES 5 TO 10 DEGREES WARMER THAN NORMAL.
THE NEXT CHANCE FOR MEASURABLE PRECIPITATION WILL BE LATE THIS
COMING WEEK AS A DEEP TROUGH MOVES IN FROM THE NORTHWEST. THE
MODELS CONTINUE TO BRING DEEP COLD AIR IN BEHIND THE FRONT...WITH
-7C 850MB TEMPS POSSIBLE NEXT SATURDAY NIGHT. EXPECT TEMPERATURES
NEXT WEEKEND TO BE BELOW NORMAL...WITH RAIN SHOWERS POSSIBLE OUT
AHEAD OF THE FRONT...FOLLOWED BY A RIBBON OF MIXED
PRECIPITATION...AND SNOW SHOWERS BEHIND. THERE IS TO MUCH
VARIABILITY TO GIVE A GOOD QUANTIFICATION OF SNOW AMOUNTS.
HOWEVER...CURRENTLY ANY ACCUMULATIONS SEEM TO BE LIGHT. THE EC
CONTINUES TO SLOWS THE SYSTEM DOWN...ABOUT 12 HRS SLOWER THAN THE
GFS. HOWEVER BOTH MODELS HAVE A SIMILAR ORIENTATION..THOUGH THE EC
HAS A DEEPER LOW THAT IS FURTHER SOUTH.
&&
.AVIATION /10Z MONDAY THROUGH FRIDAY/...
SOME LOWER CIGS OVER SOUTHERN PA...STILL CLEAR TO THE NORTH.
LOW CLDS MAY MOVE A LITTLE FURTHER NORTH...BEFORE BURNING OFF
BETWEEN 14 AND 15Z.
OTHERWISE...HIGH PRESSURE ACROSS EASTERN CANADA AND THE NEW
ENGLAND STATES WILL REMAIN NEARLY STATIONY FOR THE NEXT FEW
DAYS...BRINGING MAINLY CLEAR SKIES TO THE AREA.
OUTLOOK...
WED...PATCHY AM VALLEY FOG POSSIBLE ACROSS THE ALLEGHENIES.
THU-FRI...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...DEVOIR/LAMBERT
SHORT TERM...DEVOIR/LAMBERT
LONG TERM...DEVOIR/CERU
AVIATION...FITZGERALD/MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
403 AM EST MON NOV 19 2012
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE OVER THE EASTERN UNITED STATES WILL
KEEP THE REGION FAIR AND DRY FOR MOST OF THIS WEEK. IN GENERAL...
SUNNY DAYS AND COOL NIGHTS ARE EXPECTED WITH SOME PATCHY FOG. MUCH
COLDER WEATHER IS EXPECTED BY NEXT WEEKEND AS A POOL OF COLD
CANADIAN AIR SPILLS ACROSS THE GREAT LAKES AND ACROSS THE
NORTHEASTERN UNITED STATES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW CLOUDS HAVE EXPANDED TO COVER MOST OF THE LAUREL HIGHLANDS AND
PORTIONS OF THE SOUTH CENTRAL MOUNTAINS THIS MORNING. PATCHY LOW
CLOUDS HAVE ALSO PROPOGATED INTO PARTS OF THE CENTRAL AND NORTHERN
MOUNTAINS AS WELL. THE EASTERLY FLOW AROUND THE CANADIAN MARITIME
STRONG SFC RIDGE CENTER AND LOW PRESSURE ORGANIZING ALONG THE
SOUTHEAST ATLANTIC COAST IS SHUNTING ENOUGH LOW LEVEL MOISTURE
WESTWARD AND UP AGAINST THE HIGHER TERRAIN OF SOUTH CENTRAL AND
CENTRAL PA IN THE PRESENCE OF WEAK VERTICAL MIXING TO PRODUCE THE
LOW CLOUDS. TEMPS UNDER THE STRATUS MODERATE TO THE LOWER TO
MIDDLE 30S...WHILE AREAS AWAY FROM THE STRATUS ARE IN THE UPPER
20S. PATCHY FOG IS ALSO PREVALENT IN THE CLEAR AREAS...WITH VSBYS
BETWEEN 3 AND 5 MILES THIS MORNING.
STRATO CU CLOUDS SHOULD PERSIST ACROSS THE CENT MTNS AND LAURELS
THROUGH LATE MORNING THE EASTERLY UPSLOPE FLOW OF LLVL MARINE AIR
CONTINUES. EARLY MORNING FOG WILL DECREASE BY MID MORNING...WHILE
THE STRATUS LARGELY DISSIPATES BY LATE MORNING. PARTLY TO MOSTLY
SUNNY SKIES WILL DEVELOP BY THE LATE MORNING NEAR AND TO THE EAST
OF A LINE FROM KIPT TO KSEG AND KMDT. HOWEVER...NAM12 OUTLIER
SOLUTION SHOWS STRATUS PERSISTING OVER THE LOWER SUSQ THROUGH THIS
AFTERNOON...WHILE LCL 3KM HRRR SHOWS DISSIPATING AFT 15Z. TEMPS
WILL HAVE TO BE WATCHED CLOSELY AS MORE EXPANSIVE AND PERSISTENT
LOW CLOUDS COULD HOLD DOWN MAXES ACROSS CENTRAL AND SOUTHWEST
PORTIONS OF CENTRAL PA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
EXPECT MORE OF THE SAME TONIGHT INTO TUESDAY MORNING WITH AT LEAST
A COMPONENT OF RETURN/UPSLOPE FLOW ACTING TO PRODUCE AREAS OF LOW
CLOUDS WITH TIES TO THE LAUREL HIGHLANDS AND SOUTH CENTRAL
MOUNTAINS. SFC RIDGE AXIS REMAINS ANCHORED OVER EASTERN THIRD OF
PENNSYLVANIA TONIGHT AND TUESDAY...AND IT APPEARS THE EASTERLY
ATLANTIC FETCH WILL BECOME MORE NE TO SW ORIENTED BY 12Z TUE...
SO EXTENT OF STRATUS IS EXPECTED TO BE FAR LESS ON TUESDAY MORNING
THAN THIS MORNING...BUT WITH THE TYPICAL RIVER VALLEY FOG THAT
ACCOMPANIES STABLE STRATIFICATION OVER CENTRAL AND EASTERN PA.
MINS TONIGHT SHOULD RANGE FROM THE MID TO UPPER 20S ACROSS THE
NORTH TO THE LOWER 30S OVER THE SOUTHEAST. GENERALLY STAYED A FEW
TICKS ABOVE MOS...WHICH MAY BE UNDERDOING THE EXTENT OF FOG AND
LOW CLOUDS EARLY TUESDAY MORNING. HIGHS SHOULD MODERATE TO THE 50S
EVERYWHERE TUESDAY AFTERNOON.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
EXPECT A DIGGING TROUGH TO MOVE THROUGH EARLY WEDNESDAY. THIS
WILL BRING SOME SLIGHT CLOUDINESS AND THE RETURN FLOW OF MOISTURE
AROUND THE RIDGE MAY ADVECT ENOUGH MOISTURE NORTHWARD UP THE SPINE
OF THE APPALACHIANS TO PRODUCE A LIGHT SHOWER OVER PARTS OF THE
REGION TUESDAY NIGHT. HOWEVER ANY DOWNSLOPING SHOULD REDUCE THIS
MOISTURE AND ANY PRECIPITATION REMAINS A LOW PROBABILITY. HAVE
CONTINUED TO REDUCE POPS ACCORDINGLY. EXPECT MILD AND DRY WEATHER
WITH WARMER THAN NORMAL TEMPERATURES THROUGH THE WORK WEEK...WITH
MAX TEMPERATURES 5 TO 10 DEGREES WARMER THAN NORMAL.
THE NEXT CHANCE FOR MEASURABLE PRECIPITATION WILL BE LATE THIS
COMING WEEK AS A DEEP TROUGH MOVES IN FROM THE NORTHWEST. THE
MODELS CONTINUE TO BRING DEEP COLD AIR IN BEHIND THE FRONT...WITH
-7C 850MB TEMPS POSSIBLE NEXT SATURDAY NIGHT. EXPECT TEMPERATURES
NEXT WEEKEND TO BE BELOW NORMAL...WITH RAIN SHOWERS POSSIBLE OUT
AHEAD OF THE FRONT...FOLLOWED BY A RIBBON OF MIXED
PRECIPITATION...AND SNOW SHOWERS BEHIND. THERE IS TO MUCH
VARIABILITY TO GIVE A GOOD QUANTIFICATION OF SNOW AMOUNTS.
HOWEVER...CURRENTLY ANY ACCUMULATIONS SEEM TO BE LIGHT. THE EC
CONTINUES TO SLOWS THE SYSTEM DOWN...ABOUT 12 HRS SLOWER THAN THE
GFS. HOWEVER BOTH MODELS HAVE A SIMILAR ORIENTATION..THOUGH THE EC
HAS A DEEPER LOW THAT IS FURTHER SOUTH.
&&
.AVIATION /09Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE PROVIDING SKIES AND LGT WINDS ACROSS MOST OF CENTRAL
PA LATE THIS EVENING.
HOWEVER...SATL LOOP SHOWS AN AREA OF STRATOCU EXPANDING WESTWARD
ACROSS SOUTHERN PA...THE RESULT OF AN EASTERLY FLOW OF RELATIVELY
MOIST AIR FROM THE ATLANTIC. LATEST NARRE/SREF DATA BOTH INDICATE
MOISTURE FROM THIS EASTERLY FLOW WILL BANK AGAINST THE ALLEGHENY
MTNS OVERNIGHT...CREATING THE LIKELIHOOD OF EITHER IFR CIGS OR FOG
OVR PORTIONS OF THE LAUREL HIGHLANDS AND SC MTNS. BOTH JST AND AOO
COULD POTENTIALLY SEE IFR CONDS EARLY MON AM...MAINLY BTWN 08Z-
14Z.
ADDED LOWER CIGS AT LNS...ALREADY IN THAT AREA.
ELSEWHERE ACROSS CENTRAL PA...PATCHY VALLEY FOG IS LIKELY AFTER
MIDNIGHT...BUT ESP BTWN 09Z-14Z. HOWEVER...CURRENT DWPT DEPRESSIONS
AND CONDITIONAL CLIMATOLOGY SUGGEST PREDOMINATE VSBYS AT
BFD...IPT...UNV...MDT AND LNS WILL REMAIN ABV 3SM.
ANY VALLEY FOG /OR LOW CIGS ACROSS THE LAURELS/ SHOULD LIFT BY
LATE MORNING...TYPICALLY 14Z-15Z THIS TIME OF YEAR. BY AFTN...THE
ENTIRE REGION SHOULD BE UNDER VFR CONDS AND LIGHT WINDS.
OUTLOOK...
TUE...PATCHY AM VALLEY FOG POSSIBLE ACROSS THE ALLEGHENIES.
WED-FRI...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...DEVOIR/LAMBERT
SHORT TERM...DEVOIR/LAMBERT
LONG TERM...DEVOIR/CERU
AVIATION...FITZGERALD/MARTIN
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1149 PM CST SUN NOV 18 2012
.DISCUSSION...
SEE THE 12Z AVIATION DISCUSSION BELOW.
&&
.AVIATION...
PATCHY MVFR CIGS HAVE DEVELOPED AT KSOA AND KSJT IN THE PAST HOUR
BUT REMAIN TRANSIENT FOR THE MOST PART AS THE DEVELOPING LOW LEVEL
JET WORKS TO MIX THE BOUNDARY LAYER. I DO EXPECT THE CURRENT
STRATUS OVER THE CWA TO DISSIPATE WITH TIME AS IT ADVECTS NORTH.
ADDITIONAL LOW CIGS ARE EXPECTED TO DEVELOP LATER TONIGHT AND
SPREAD NORTH INTO THE MORNING HOURS. WE MAY SEE SOME BRIEF IFR
CIGS AROUND OR AFTER 12Z BUT I THINK THE PREVAILING CIG TYPE WILL
BE MVFR. CIGS WILL ERODE BY LATE MORNING...GIVING WAY TO VFR
CONDITIONS THROUGH THE REMAINDER OF THE TAF PERIOD. LIGHT SOUTH
WINDS TONIGHT WILL INCREASE TO 10-12 KTS ON MONDAY WITH OCCASIONAL
GUSTS NEAR 20 KTS AROUND MIDDAY.
JOHNSON
&&
.PREV DISCUSSION... /ISSUED 1018 PM CST SUN NOV 18 2012/
UPDATE...
THE LATEST MODEL AND RADAR DATA INDICATE THE POTENTIAL FOR SHOWERS
HAS ENDED ACROSS WEST CENTRAL TEXAS FOR THE REMAINDER OF TONIGHT.
THE LATEST WSR-88D DATA INDICATE SHOWERS HAVE ENDED ACROSS WEST
CENTRAL TEXAS. PLUS...THE LATEST RUC SHOWS LITTLE IF ANY CHANCE
FOR CONTINUED SHOWERS TONIGHT. THUS...I HAVE REDUCED POPS GRIDS
FOR THE REMAINDER OF TONIGHT TO 10 PERCENT...AND I REMOVED ALL
WEATHER FROM THE TONIGHT WEATHER GRIDS. IN ADDITION...I ADJUSTED
SKY GRIDS FOR THE REMAINDER OF TONIGHT BASED ON SATELLITE IMAGERY
AND MODELS DATA. RECENT PRODUCT UPDATES REFLECT THESE CHANGES.
OTHERWISE...NO OTHER CHANGES TO THE FORECAST.
HUBER
PREV DISCUSSION... /ISSUED 537 PM CST SUN NOV 18 2012/
DISCUSSION...
SEE THE 00Z AVIATION DISCUSSION BELOW.
AVIATION...
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH AT LEAST 06Z
TONIGHT WITH LOW CLOUDS DEVELOPING AROUND 08-09Z AND PERSISTING
INTO THE LATE MORNING TO EARLY AFTERNOON HOURS. AS USUAL...THE NAM
IS THE MOST PESSIMISTIC MODEL REGARDING CEILING HEIGHTS /SHOWING
IFR/. BASED ON THE NAM/S BIAS OF BEING TO AGGRESSIVE WITH CIGS...
I RAISED THE FORECAST CATEGORIES TO LOW END MVFR EVERYWHERE
EXCLUDING KSOA /WHERE IFR CIGS WERE MAINTAINED/. LOW CLOUDS WILL
HANG ON THE LONGEST AT KBBD/KJCT AS VEERING LOW LEVEL DRIES OUT
KSJT/KSOA BY LATE MORNING. AT THIS TIME...IT LOOKS LIKE KABI MAY
AVOID LOW CIGS AGAIN TONIGHT. WINDS WILL BE PREDOMINANTLY FROM THE
SOUTH AT 12 KTS OR LESS...ALTHOUGH A FEW GUSTS NEAR 20 KTS WILL BE
POSSIBLE MONDAY AFTERNOON.
JOHNSON
PREV DISCUSSION... /ISSUED 404 PM CST SUN NOV 18 2012/
SHORT TERM...
FOR THE MOST PART I MADE ONLY MINOR CHANGES TO THE FORECAST. AS I
MENTIONED IN THE UPDATE EARLIER I INCREASED THE AFTERNOON HIGH
TEMPERATURES AS CLOUD COVER ARRIVED LATER THAN WE THOUGHT IT
WOULD. THIS CLOUD COVER WILL HAVE A TWO FOLD EFFECT ON THE
TEMPERATURES. AFTERNOON HIGHS ARE EXPECTED TO BE MILD AND THE
OVERNIGHT LOWS WILL ONLY DROP TO NEAR 50 DEGREES WHICH IS ABOUT 10
DEGREES ABOVE NORMAL.
PRECIPITATION CHANCES END TONIGHT AS THE SHORTWAVE TROUGH EXITS
WEST CENTRAL TEXAS. WITH THE DEPARTURE OF THE SHORTWAVE AN UPPER
LEVEL ZONAL PATTERN EMERGES AND DOMINATES THE FORECAST AREA. AS
THE CLOUDS BEGIN TO CLEAR TOMORROW MORNING...THE AFTERNOON HIGHS
ARE EXPECTED TO BE NEAR 70 DEGREES AREA WIDE.
18
LONG TERM...
GFS AND EC MODELS ARE IN GOOD AGREEMENT...WITH AN UPPER SHORTWAVE
MOVING EAST ACROSS WEST CENTRAL TEXAS...WEDNESDAY NIGHT AND
THURSDAY. A WEAK COLD FRONT FRIDAY THEN MOVES THROUGH FRIDAY.
ISOLATED SHOWERS AND PERHAPS AN ISOLATED THUNDERSTORM POSSIBLE
DURING THIS PERIOD. WITH ONLY WEAK INSTABILITY HOWEVER...GFS HAS
MUCAPES OF 100 TO 300 J/KG FRIDAY AND NONE EARLIER ON THURSDAY...
AND LIMITED MID LEVEL LAPSE RATES OF 6.5 TO 7.5 C/KM...NOT
EXPECTING MUCH THUNDER. RAINFALL AMOUNTS EXPECTED TO BE LIGHT
THURSDAY AND THURSDAY NIGHT...BUT MAY SEE HEAVIER AMOUNTS AS COLD
FRONT MOVES THROUGH SOUTHERN SECTIONS FRIDAY...MAINLY CONCHO
VALLEY AND SOUTHWARD.
GFS AND EC MODELS DIFFER THIS WEEKEND. GFS BRINGS IN AN BROAD
UPPER TROUGH WHILE THE EC HAS A BROAD WEAK RIDGING. WHILE THE GFS
PRECIPITATION ALGORITHM SOME RAIN...WILL HOLD ON MENTIONING
RAINFALL CHANCES WITH MODEL DIFFERENCES AND NORMAL LOWER CONFIDENCE
IN THE LONG TERM.
04
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 51 70 49 73 50 / 10 5 10 5 0
SAN ANGELO 50 72 51 73 50 / 10 5 10 5 5
JUNCTION 53 70 52 75 51 / 10 5 10 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
25
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1018 PM CST SUN NOV 18 2012
.UPDATE...
THE LATEST MODEL AND RADAR DATA INDICATE THE POTENTIAL FOR SHOWERS
HAS ENDED ACROSS WEST CENTRAL TEXAS FOR THE REMAINDER OF TONIGHT. THE
LATEST WSR-88D DATA INDICATE SHOWERS HAVE ENDED ACROSS WEST CENTRAL
TEXAS. PLUS...THE LATEST RUC SHOWS LITTLE IF ANY CHANCE FOR
CONTINUED SHOWERS TONIGHT. THUS...I HAVE REDUCED POPS GRIDS FOR THE
REMAINDER OF TONIGHT TO 10 PERCENT...AND I REMOVED ALL WEATHER
FROM THE TONIGHT WEATHER GRIDS. IN ADDITION...I ADJUSTED SKY GRIDS
FOR THE REMAINDER OF TONIGHT BASED ON SATELLITE IMAGERY AND MODELS
DATA. RECENT PRODUCT UPDATES REFLECT THESE CHANGES. OTHERWISE...NO
OTHER CHANGES TO THE FORECAST.
HUBER
&&
.PREV DISCUSSION... /ISSUED 537 PM CST SUN NOV 18 2012/
DISCUSSION...
SEE THE 00Z AVIATION DISCUSSION BELOW.
AVIATION...
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH AT LEAST 06Z
TONIGHT WITH LOW CLOUDS DEVELOPING AROUND 08-09Z AND PERSISTING
INTO THE LATE MORNING TO EARLY AFTERNOON HOURS. AS USUAL...THE NAM
IS THE MOST PESSIMISTIC MODEL REGARDING CEILING HEIGHTS /SHOWING
IFR/. BASED ON THE NAM/S BIAS OF BEING TO AGGRESSIVE WITH CIGS...
I RAISED THE FORECAST CATEGORIES TO LOW END MVFR EVERYWHERE
EXCLUDING KSOA /WHERE IFR CIGS WERE MAINTAINED/. LOW CLOUDS WILL
HANG ON THE LONGEST AT KBBD/KJCT AS VEERING LOW LEVEL DRIES OUT
KSJT/KSOA BY LATE MORNING. AT THIS TIME...IT LOOKS LIKE KABI MAY
AVOID LOW CIGS AGAIN TONIGHT. WINDS WILL BE PREDOMINANTLY FROM THE
SOUTH AT 12 KTS OR LESS...ALTHOUGH A FEW GUSTS NEAR 20 KTS WILL BE
POSSIBLE MONDAY AFTERNOON.
JOHNSON
PREV DISCUSSION... /ISSUED 404 PM CST SUN NOV 18 2012/
SHORT TERM...
FOR THE MOST PART I MADE ONLY MINOR CHANGES TO THE FORECAST. AS I
MENTIONED IN THE UPDATE EARLIER I INCREASED THE AFTERNOON HIGH
TEMPERATURES AS CLOUD COVER ARRIVED LATER THAN WE THOUGHT IT
WOULD. THIS CLOUD COVER WILL HAVE A TWO FOLD EFFECT ON THE
TEMPERATURES. AFTERNOON HIGHS ARE EXPECTED TO BE MILD AND THE
OVERNIGHT LOWS WILL ONLY DROP TO NEAR 50 DEGREES WHICH IS ABOUT 10
DEGREES ABOVE NORMAL.
PRECIPITATION CHANCES END TONIGHT AS THE SHORTWAVE TROUGH EXITS
WEST CENTRAL TEXAS. WITH THE DEPARTURE OF THE SHORTWAVE AN UPPER
LEVEL ZONAL PATTERN EMERGES AND DOMINATES THE FORECAST AREA. AS
THE CLOUDS BEGIN TO CLEAR TOMORROW MORNING...THE AFTERNOON HIGHS
ARE EXPECTED TO BE NEAR 70 DEGREES AREA WIDE.
18
LONG TERM...
GFS AND EC MODELS ARE IN GOOD AGREEMENT...WITH AN UPPER SHORTWAVE
MOVING EAST ACROSS WEST CENTRAL TEXAS...WEDNESDAY NIGHT AND
THURSDAY. A WEAK COLD FRONT FRIDAY THEN MOVES THROUGH FRIDAY.
ISOLATED SHOWERS AND PERHAPS AN ISOLATED THUNDERSTORM POSSIBLE
DURING THIS PERIOD. WITH ONLY WEAK INSTABILITY HOWEVER...GFS HAS
MUCAPES OF 100 TO 300 J/KG FRIDAY AND NONE EARLIER ON THURSDAY...
AND LIMITED MID LEVEL LAPSE RATES OF 6.5 TO 7.5 C/KM...NOT
EXPECTING MUCH THUNDER. RAINFALL AMOUNTS EXPECTED TO BE LIGHT
THURSDAY AND THURSDAY NIGHT...BUT MAY SEE HEAVIER AMOUNTS AS COLD
FRONT MOVES THROUGH SOUTHERN SECTIONS FRIDAY...MAINLY CONCHO
VALLEY AND SOUTHWARD.
GFS AND EC MODELS DIFFER THIS WEEKEND. GFS BRINGS IN AN BROAD
UPPER TROUGH WHILE THE EC HAS A BROAD WEAK RIDGING. WHILE THE GFS
PRECIPITATION ALGORITHM SOME RAIN...WILL HOLD ON MENTIONING
RAINFALL CHANCES WITH MODEL DIFFERENCES AND NORMAL LOWER CONFIDENCE
IN THE LONG TERM.
04
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 51 70 49 73 50 / 10 5 10 5 0
SAN ANGELO 50 72 51 73 50 / 10 5 10 5 5
JUNCTION 53 70 52 75 51 / 10 5 10 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
HUBER
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1048 AM PST Mon Nov 19 2012
.SYNOPSIS...
Expect a progressive and wet weather pattern with periods of mountain
snow and valley rain this week. Higher snow levels through the middle
of the work week will combine with the heaviest expected
precipitation in this forecast cycle to produce rises on the area
small streams or creeks...especially for North Idaho and the
Cascades. Windy conditions will develop over portions of the Inland
Northwest on Monday.
&&
.DISCUSSION...
Updated much of today`s forecast to reflect the current
radar/satellite/observation trends. Rain shadow is keeping much of
the western Basin dry but HRRR and NAM suggest that a ripple in
the southwesterly flow could offset the shadow for a few hours
of rain this afternoon. Same goes for the L-C valley remaining
mostly dry. Elsewhere rain and mountain snow will continue through
today and then taper off northwest to southeast overnight. The
southeast areas (e.g. southern Palouse, southern Panhandle) will
probably not see an end to the rain as the pseudo-cold front will
stall out over that area tonight.
Also adjusted many of the high temperatures upward for today.
Already into the lower 60s in the lower Columbia Basin and lower
50s into the upper basin.
On the wind front, we decided to downgrade the High Wind Warning
over the Palouse and Pomeroy areas to a Wind Advisory. The winds
aloft certainly support a warning, but mixing that wind down to
the surface is very difficult in this situation of warm advection
and rain-cooled air. Gusts to 40 mph will be fairly common but
damaging winds should remain in the upper elevations, so left the
warning in place for the Blue Mountains.
&&
.AVIATION...
18Z TAFs: Strong warm front will bring periods of -RA/RA to most of
the sites at least through 00z Tue. The exceptions will be in the
lee of the Cascades, KEAT and KWMH, as well as KLWS due to
downslope wind influence. The remaining sites which will see the
precipitation will generally experience VFR cigs...however during
heavier spurts of rain...brief MVFR cigs will be psbl. The threat
was not great enough to list as a prevailing condition. Much of
the precipitation threat will wane during the evening. A weak cold
front will sweep through the area overnight and will likely bring
another batch of rain and lower cigs to most of the sites.
Confidence is fair as most of the MOS data was hinting at MVFR
cigs and psbly IFR ones developing aft 09z or so. The other
concern through the day will be winds. Strong winds of 40-50 kts
will remain poised about 1k above the ground. Whether these can
mix down is the big question. Typically warm fronts accompanied by
widespread precipitation do not allow the atmosphere to fully mix
and this is the way we will trend the forecast. Even so breezy
conditions with sustained speeds of 15-22kts are expected at most
sites with gusts in the 28-35kt range. Winds will decrease before
midnight. fx
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 47 42 46 39 44 32 / 100 100 80 80 80 40
Coeur d`Alene 47 41 46 38 44 33 / 100 100 90 90 80 40
Pullman 50 42 50 40 44 34 / 100 100 90 80 80 30
Lewiston 57 46 55 43 51 38 / 20 100 80 60 70 20
Colville 46 39 47 39 43 33 / 100 80 80 90 80 40
Sandpoint 44 38 45 37 43 34 / 100 100 100 100 100 70
Kellogg 43 40 44 37 41 33 / 100 100 100 100 100 60
Moses Lake 56 42 49 38 47 33 / 30 40 50 40 50 10
Wenatchee 56 40 47 38 44 35 / 70 30 60 50 50 20
Omak 48 40 45 36 42 31 / 100 50 60 60 60 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Flood Watch through late Tuesday night for Central Panhandle
Mountains-Coeur d`Alene Area-Idaho Palouse-Northern
Panhandle.
Winter Storm Warning until 4 PM PST this afternoon for Central
Panhandle Mountains-Northern Panhandle.
Wind Advisory until 10 PM PST this evening for Coeur d`Alene
Area-Idaho Palouse-Lewis and Southern Nez Perce Counties-
Lewiston Area.
WA...Flood Watch through late Tuesday night for Northeast Mountains-
Okanogan Highlands-Spokane Area-Washington Palouse.
Winter Storm Warning until 4 PM PST this afternoon for Northeast
Mountains-Okanogan Highlands.
High Wind Warning until 10 PM PST this evening for Northeast
Blue Mountains.
Wind Advisory until 10 PM PST this evening for Lower Garfield
and Asotin Counties-Moses Lake Area-Spokane Area-Upper
Columbia Basin-Washington Palouse.
Flood Watch through late tonight for East Slopes Northern
Cascades.
Winter Storm Warning until 10 PM PST this evening for East
Slopes Northern Cascades.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
530 PM CST TUE NOV 20 2012
.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT
301 PM CST TUE NOV 20 2012
MAIN FORECAST CONCERN IS ON CLOUDS/FOG POTENTIAL
TONIGHT...TEMPERATURES THROUGH THE PERIOD AND RAIN CHANCES FOR
THANKSGIVING DAY.
VISIBLE SATELLITE IMAGERY AT 18Z SHOWS AN AREA OF FOG ALONG THE
MISSISSIPPI RIVER AND ACROSS SOUTHWEST WISCONSIN AND EASTERN IOWA.
THIS AREA HAS BEEN SHRINKING OVER THE PAST SEVERAL HOURS AND EXPECT
IT TO DISSIPATE BY EVENING. OTHERWISE SKIES WERE CLEAR AROUND THE AREA.
20.12Z MODELS CONTINUE TO BE IN GOOD AGREEMENT THROUGH THE PERIOD.
NAM IS THE FASTEST SOLUTION IN REGARD TO THE FRONTAL MOVEMENT ON
THANKSGIVING DAY AND WENT MORE WITH A MODEL CONSENSUS WITH ITS
MOVEMENT ACROSS THE FORECAST AREA.
IN THE NEAR TERM...PROBLEM IS ON FOG AND LOW CLOUD POTENTIAL AGAIN
TONIGHT. RAP BUFKIT SOUNDINGS SHOW MOISTURE BEING TRAPPED UNDER THE
STRENGTHENING INVERSION TONIGHT...BUT NAM WANTS TO SCOUR THINGS OUT
WITH DRIER AIR FILTERING IN FROM THE WEST. HOWEVER...FEEL RAP MAYBE
MORE ACCURATE AS GRADIENT LOOKS TO BE QUITE WEAK UNTIL LATER TONIGHT
WHEN THE WINDS PICK UP ACROSS THE WEST. FEEL WIDESPREAD FOG IS AGAIN
LIKELY...MAINLY IN AREAS ALONG AND EAST OF THE MISSISSIPPI RIVER.
ATTENTION THEN TURNS TO BUILDING UPPER RIDGE ACROSS THE AREA
WEDNESDAY. 925MB TEMPERATURES WILL WARM INTO THE LOWER TO MIDDLE
TEENS CELSIUS BY AFTERNOON AND THUS EXPECT VERY WARM TEMPERATURES.
MIXING POTENTIAL LOOKS TO BE BETWEEN 925MB AND 950MB AND USING THE
MIX DOWN TOOL RESULTS IN A 10 DEGREE DIFFERENCE BETWEEN MIXING TO
925MB AND 950MB. THE CAVEAT WILL BE LINGERING CLOUDS AND FOG
EXPECTED INTO THE MID MORNING HOURS THAT MAY PREVENT FULL WARMING.
NONE THE LESS FORECAST IS BASED ON CLOUDS/FOG DISSIPATING BY MID
MORNING AND COMBINED WITH A MILD START WILL STILL MAKE IT INTO THE
MID 50S ACROSS THE NORTH TO THE MID 60S IN THE CENTRAL AND SOUTH.
ANOTHER MILD NIGHT IS EXPECTED WEDNESDAY NIGHT WITH SOUTHERLY LOW
LEVEL FLOW CONTINUING AHEAD OF AN APPROACHING COLD FRONT. THE COLD
FRONT WILL REMAIN WEST OF THE AREA THROUGH THE OVERNIGHT HOURS.
ANOTHER MILD DAY IS EXPECTED THANKSGIVING DAY AS THE FRONTAL PASSAGE
LOOKS LIKE IT WILL OCCUR DURING THE AFTERNOON HOURS. AS MENTIONED
PREVIOUSLY...NAM IS THE FASTEST SOLUTION AND USED A MODEL CONSENSUS.
IN EITHER CASE...THE COLDER AIR LAGS BEHIND AND WILL NOT ARRIVE
UNTIL THURSDAY NIGHT. GFS CONTINUES TO BE THE ONLY MODEL THAT
GENERATES SHOWERS OVER SOUTHWEST WISCONSIN...WITH THE GEM AND ECMWF
KEEPING THE RAIN JUST SOUTH OF THE AREA. WILL CONTINUE LOWER END
PROBABILITIES ACROSS FAR SOUTHWEST WISCONSIN.
STRONG COLD ADVECTION EXPECTED BEHIND THE FRONT THURSDAY NIGHT ALONG
WITH A TIGHTENING PRESSURE GRADIENT. STRATUS LOOKS TO ADVECT
SOUTHWARD AS THE NIGHT WEARS ON...ESPECIALLY ACROSS THE NORTHERN
HALF OF THE FORECAST AREA. THESE CLOUDS WILL THEN CONTINUE INTO
FRIDAY. PRESSURE GRADIENT RATHER TIGHT FRIDAY AND LOOKS LIKE A
BLUSTERY AND COLD DAY WITH TEMPERATURES ONLY CLIMBING A FEW DEGREES
FROM THE MORNING LOWS. BETTER CHANCES FOR LIGHT SHOW/RAIN WILL BE
ACROSS THE NORTH AND WILL CONTINUE THE LOWER END PROBABILITIES IN
THESE AREAS. HIGH PRESSURE THEN BUILDS EASTWARD FROM THE PLAINS
FRIDAY NIGHT AND WITH CLEAR SKIES EXPECTED...LOWS WILL BE IN THE
TEENS TO LOWER 20S.
.LONG TERM...
301 PM CST TUE NOV 20 2012
MEDIUM RANGE MODELS DO SHOW SOME DIFFERENCES IN THIS TIME FRAME.
20.12Z ECMWF HAS BACKED OFF ON A NEGATIVELY TILTED TROUGH DEVELOPING
EARLY NEXT WEEK AND NOW HAS MAINLY A ZONAL FLOW REGIME. GFS AND
ECMWF DO DIFFER WITH SOME SUBTLE WAVES EXPECTED TO TRANSLATE THROUGH
THE FLOW FROM SUNDAY THROUGH TUESDAY. SURFACE HIGH PRESSURE WILL
DOMINATE THE PATTERN SATURDAY...BUT AFTER THAT CONFIDENCE IS RATHER
LOW IN ANY ONE SOLUTION AND THUS HAVE WENT WITH THE MODEL CONSENSUS.
TEMPERATURES LOOK TO REMAIN BELOW NORMAL THROUGH THE PERIOD...WITH
HIGHS MAINLY IN THE 30S WITH LOWS IN THE TEENS AND 20S.
&&
.AVIATION...TONIGHT AND WEDNESDAY
530 PM CST TUE NOV 20 2012
THINKING HAS NOT CHANGED MUCH SINCE NOON. A VERY PROBLEMATIC PERIOD
TONIGHT/EARLY WED WITH ABUNDANT LOW LEVEL MOISTURE TRAPPED UNDER A
RATHER STRONG INVERSION NEAR 925 MB. LIGHT WINDS/LIMITED MIXING THIS
TIME OF YEAR HAVE RESULTED IN PERSISTENT IFR/LIFR FOG/CIGS 10-30
MILES EITHER SIDE OF THE MS RIVER...ALREADY EXPANDING EAST/WEST AS
OF 23Z. RADIATIONAL COOLING/LIGHT WINDS UNDER THE INVERSION WILL
ALLOW THE FOG TO CONTINUE THICKENING/SPREADING THIS EVENING...
KEEPING THE KLSE AREA IN IFR/LIFR CONDITIONS TONIGHT INTO WED
MORNING. SFC PRESSURE GRADIENT TIGHTENS TONIGHT AND INTO WED...
ALLOWING FOR BOUNDARY LAYER MIXING UNDER THE INVERSION. THIS
EXPECTED TO RESULT IN MORE MVFR VSBYS IN HZ/BR AND SCT LOW STRATUS
AT HIGHER ELEVATION SITES WEST OF THE MS RIVER...LIKE KRST. GRADIENT
CONTINUES TO TIGHTEN WED WITH WARMER/DRIER AIR ADVECTING/MIXING IN
FROM THE SOUTHWEST. GIVEN THE TIME OF YEAR... IFR/MVFR VSBYS AND
SOME IFR CIGS LIKELY TO PERSIST THRU MUCH OF WED MORNING ALONG/EAST
OF THE MS RIVER...BEFORE CONDITIONS IMPROVE WITH DEEPER MIXING/
EROSION OF THE INVERSION FOR THE MID-DAY/AFTERNOON HOURS.
&&
.CLIMATE...
200 AM CST SUN NOV 18 2012
RECORD HIGH TEMPERATURES FOR WEDNESDAY/21ST AND THURSDAY/22ND. COOP
SITES ARE 7 AM-7 AM HIGHS...THUS 22ND HIGHS ARE 21.12Z TO 22.12Z.
LA CROSSE AND ROCHESTER ARE THE ONLY NON-COOP SITES.
FORECAST HIGH TEMPERATURES SUGGEST SOME OF THE RECORDS BELOW MAY
BE TIED OR BROKEN.
LOCATION WEDNESDAY/21ST THURSDAY/22ND
LA CROSSE WI 72/1990 59/1963
SPARTA WI 65/1990 70/1990
MEDFORD WI 59/1913 65/1990
LANCASTER WI 66/2003 66/1898
MAUSTON WI 67/2003 66/1990
ROCHESTER MN 69/1990 65/1913
AUSTIN MN 70/1990 58/1966
WINONA DAM 5A MN 60/2003 60/2001
WABASHA MN 61/1908 59/1908
CHARLES CITY IA 71/1990 62/1966
OELWEIN IA 71/1990 62/1966
DECORAH IA 71/1990 62/1908
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
301 PM CST TUE NOV 20 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RABERDING
LONG TERM...RABERDING
AVIATION.....RRS
CLIMATE......JONES/DB/AJ/BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
250 PM CST MON NOV 19 2012
.SHORT TERM...
250 PM CST MON NOV 19 2012
MAIN FORECAST CONCERN IS ON SKY CONDITIONS TONIGHT AND THEN
TEMPERATURES THROUGH THE REMAINDER OF THE PERIOD.
18Z WATER VAPOR IMAGERY SHOWS A SHORTWAVE OVER NORTHERN
ILLINOIS/EASTERN IOWA...WHILE ANOTHER SHORTWAVE WAS LOCATED OVER
NORTH DAKOTA. THIS LEAD SHORTWAVE IS SPREADING THE SCATTERED
SHOWERS INTO EASTERN WISCONSIN. MEANWHILE...VISIBLE SATELLITE
IMAGERY SHOWS BACK EDGE OF CLOUDS EXTENDING FROM NEAR THE TWIN
CITIES TO CHARLES CITY IOWA AND MOVING STEADILY EASTWARD.
19.12Z MODELS IN GOOD AGREEMENT THROUGH THE PERIOD WITH THE OVERALL
PATTERN. STILL SOME TIMING DIFFERENCES WITH FRONT THE MOVES THROUGH
THE AREA THANKSGIVING DAY...BUT LOOK TO HAVE MINIMAL IMPACT ON THE
SENSIBLE WEATHER.
IN THE NEAR TERM...LEAD SHORTWAVE WILL PUSH NORTHEAST AWAY FROM THE
AREA THIS EVENING...WITH CLEARING SKIES IN ITS WAKE ACROSS MAINLY
THE WESTERN COUNTIES. HOWEVER...SECOND WAVE DROPPING FROM THE
NORTHERN PLAINS WILL PUSH A COLD FRONT TOWARDS THE AREA THIS
EVENING. 19.12Z NAM/19.16Z RAP BUFKIT SOUNDINGS INDICATING THE
DEVELOPMENT OF STRATUS ACROSS THE AREA TONIGHT...THIS ALSO IN LINE
WITH INCREASING PROBABILITIES IN THE 19.09Z SREF. THUS AFTER SOME
CLEARING EARLY THIS EVENING IN THE WEST...EXPECT STRATUS TO DEVELOP
THROUGH THE OVERNIGHT HOURS BEFORE DRIER AIR ADVECTS INTO THE AREA
AFTER 09Z-12Z. DID INCREASE SKY COVER TONIGHT FROM PREVIOUS FORECAST.
STRATUS WILL BREAK UP TUESDAY MORNING..WITH ATTENTION THEN TURNING
TO UPPER RIDGE BUILDING IN AND ITS AFFECT ON TEMPERATURES. 925MB
TEMPERATURES CLIMB FROM 7 TO 9 DEGREES ON TUESDAY...TO 10 TO 13
DEGREES ON WEDNESDAY. WITH PLENTY OF SUNSHINE EXPECTED ALONG WITH
MIXING TO BETWEEN 925MB-950MB...EXPECT TEMPERATURES TO WARM TO WELL
ABOVE GUIDANCE VALUES. 850MB TEMPERATURE ANOMALIES ARE NEARLY 2
STANDARD DEVIATIONS ABOVE NORMAL ON WEDNESDAY AND THUS EXPECT
TEMPERATURES NEAR RECORDS IN SOME LOCATIONS (SEE CLIMATE SECTION
BELOW FOR A LIST OF RECORDS). WITH A CONTINUED SOUTHERLY FLOW
WEDNESDAY NIGHT...MILD TEMPERATURES WILL CONTINUE WITH LOWS ONLY IN
THE 40S.
ON THURSDAY...RIDGE BREAKS DOWN AS SHORTWAVE ROTATES ACROSS THE
PLAINS PUSHING A COLD FRONT ACROSS THE AREA THROUGH THE DAY. STILL
SOME SLIGHT TIMING DIFFERENCES BETWEEN THE MODELS...BUT THE COLDER
AIR LOOKS TO LAG BEHIND THE FRONT...NOT ARRIVING UNTIL THURSDAY
NIGHT. A PLUME OF LOW LEVEL MOISTURE AHEAD OF IT STREAMING INTO
SOUTHWEST AND CENTRAL WISCONSIN. 19.12Z GFS IS SHOWING 100 TO 150
J/KG OF MOST UNSTABLE CAPE WITH THE MOISTURE PLUME AND DOES GENERATE
SOME SHOWERS. DID KEEP THE LOWER END PROBABILITIES WITH THIS FEATURE
ACROSS MAINLY THE SOUTHEASTERN HALF OF THE FORECAST AREA.
BY THURSDAY NIGHT FRONT WILL BE EAST OF THE AREA..WITH THE UPPER
LEVEL TROUGH SWINGING THROUGH NORTHERN WISCONSIN. DID ADD LOWER END
PRECIPITATION CHANCES TO THE FAR NORTH FOR A CHANCE OF RAIN/SNOW.
.LONG TERM...
250 PM CST MON NOV 19 2012
SYSTEM DEPARTS ON FRIDAY...WITH CYCLONIC FLOW ACROSS THE AREA.
TEMPERATURES WILL BE BELOW NORMAL WITH HIGHS MAINLY IN THE 30S. MAIN
PRECIPITATION CHANCE WILL BE ACROSS THE FAR NORTH.
OTHERWISE...REMAINDER OF THE PERIOD WILL BE DOMINATED BY SEASONAL TO
BELOW NORMAL TEMPERATURES. BEST CHANCE FOR ANY PRECIPITATION LOOKS BE
ON MONDAY...BUT MODELS SHOWING SOME DIFFERENCES WITH A DEVELOPING
TROUGH ACROSS THE CENTRAL CONUS. 19.12Z ECMWF SHOWS THIS FEATURE
WITH CYCLOGENESIS OCCURRING...WHILE THE GFS KEEPS FLOW MORE ZONAL. IF
THE ECMWF DOES VERIFY WILL HAVE TO WATCH THIS SYSTEM FOR PERIODS
BEYOND MONDAY.
&&
.AVIATION...THROUGH 18Z TUESDAY
1156 AM CST MON NOV 19 2012
CURRENTLY WATCHING A MID-LEVEL TROUGH AND WEAK SURFACE COLD FRONT
MOVING THROUGH THE REGION. MOST OF THE SCATTERED RAIN SHOWER
ACTIVITY TIED TO THIS MID-LEVEL TROUGH AND FRONT WAS NOW OVER
CENTRAL AND EASTERN WI WITH MID-CLOUD LINGERING ACROSS THE REST OF
THE AREA. SIGNAL IS SHOWING UP TONIGHT FOR STRATUS/FOG POTENTIAL
GIVEN WEAK PRESSURE GRADIENT/LIGHT WINDS AND FAIRLY MOIST LOWER
BOUNDARY LAYER FROM TODAYS SCATTERED RAINFALL. HAVE INCLUDED IFR
STRATUS AT KLSE FROM 06-09Z. NOT AS CONFIDENT AT KRST THOUGH WHERE
LIGHT NORTHWEST WINDS AFTER 06Z AND LACK OF RAINFALL/DRIER LOWER
BOUNDARY LAYER MAY PREVENT WIDESPREAD DEVELOPMENT. THIS WILL HAVE
TO BE MONITORED CLOSELY. LOOKING FOR IMPROVING/VFR CONDITIONS BY
LATE TUESDAY MORNING AS DRIER AIR SPREADS INTO THE AREA.
&&
.CLIMATE...
200 AM CST SUN NOV 18 2012
RECORD HIGH TEMPERATURES FOR WEDNESDAY/21ST AND THURSDAY/22ND. COOP
SITES ARE 6AM-6AM HIGHS...THUS 22ND HIGHS ARE 21.12Z TO 22.12Z. LA
CROSSE AND ROCHESTER ARE ONLY NON-COOP SITES.
FORECAST HIGH TEMPERATURES SUGGEST SOME OF THE RECORDS BELOW MAY
BE TIED OR BROKEN.
LOCATION WEDNESDAY/21ST THURSDAY/22ND
LA CROSSE WI 72/1990 59/1963
SPARTA WI 65/1990 70/1990
MEDFORD WI 59/1913 65/1990
LANCASTER WI 66/2003 66/1898
MAUSTON WI 67/2003 66/1990
ROCHESTER MN 69/1990 65/1913
AUSTIN MN 70/1990 58/1966
WINONA DAM 5A MN 60/2003 60/2001
WABASHA MN 61/1908 59/1908
CHARLES CITY IA 71/1990 62/1966
OELWEIN IA 71/1990 62/1966
DECORAH IA 71/1990 62/1908
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
250 PM CST MON NOV 19 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RABERDING
LONG TERM...RABERDING
AVIATION...DAS
CLIMATE......JONES/DB/AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1156 AM CST MON NOV 19 2012
.SHORT TERM...THROUGH WEDNESDAY NIGHT
200 AM CST MON NOV 19 2012
MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES TODAY AND HOW
WARM WE WILL GET ON WEDNESDAY.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A DEEP TROUGH JUST OFF BRITISH COLUMBIA...THEN A
WEST-SOUTHWEST FLOW FROM CALIFORNIA INTO THE WESTERN GREAT LAKES
REGION. WITHIN THIS FLOW...A WEAK SHORTWAVE TROUGH STRETCHED FROM
WESTERN IOWA INTO CENTRAL KANSAS. AHEAD OF THIS SHORTWAVE TROUGH...A
PLUME OF PRECIPITABLE WATER VALUES OF 0.75 INCHES OR SO CAN BE SEEN
ON GOES DERIVED IMAGERY...STREAMING NORTH FROM OKLAHOMA INTO NORTH
CENTRAL IOWA. PROFILER AND VWP DATA SHOWED 850MB WINDS OF 30-40 KT
WITHIN THIS PLUME OF MOISTURE...HELPING TO ADVECT IT NORTHEAST
TOWARDS THE FORECAST AREA. THE COMBINATION OF THIS MOISTURE
TRANSPORT AND WEAK DPVA AHEAD OF THE SHORTWAVE TROUGH HAS BEEN
SUPPORTING A BAND OF SHOWERS JUST EAST OF I-35 IN IOWA. IN
ADDITION TO THE ADVECTION OF MOISTURE...THE WINDS AS WELL AS
CLOUDS ARE HELPING TO KEEP TEMPERATURES UP IN THE 40S AND EVEN
AROUND 50 AT SOME LOCATIONS. LAST ITEM OF NOTE WAS ANOTHER WEAK
SHORTWAVE TROUGH OVER EASTERN MONTANA. DRIER AIR PRESENT OVER THE
NORTHERN PLAINS...AS SEEN ON THE 00Z BIS AND GGW SOUNDINGS...HAS
KEPT ANY CLOUD COVER TO SCATTERED HIGH BASED ALTOSTRATUS AND
CIRRUS WITH THIS SHORTWAVE TROUGH.
TODAY AND TONIGHT...THE SHORTWAVE TROUGH JUST OFF TO OUR SOUTHWEST
IS PROGGED TO LIFT NORTHEAST AND MOVE THROUGH MUCH OF THE FORECAST
AREA BY 21Z TODAY. MEANWHILE...THAT NEXT SHORTWAVE TROUGH OVER
MONTANA LOOKS TO DROP DOWN INTO THE FORECAST AREA AFTER 06Z TONIGHT
IN THE WAKE OF THE FIRST TROUGH. MOST OF THE FOCUS IS ON THE
SHORTWAVE TROUGH TODAY AS IT HAS THE MOST MOISTURE TO WORK WITH.
PRECIPITABLE WATER FORECASTS SHOW THE AREA OF MOISTURE IN CENTRAL
IOWA SPREADING NORTHEAST THROUGH THE FORECAST AREA...THEN SLOWLY
SHIFTING EAST THIS AFTERNOON THROUGH TONIGHT AS THE SHORTWAVE TROUGH
EXITS THE FORECAST AREA. SEEING THAT THE WEAK DPVA AND ISENTROPIC
LIFT HAS BEEN ABLE TO PRODUCE THE BAND OF SHOWERS NEAR I-35 IN
IOWA...FEEL CONFIDENT THAT SHOWERS WILL AFFECT THE FORECAST AREA
TODAY. HRRR RUNS SINCE 19.01Z HAVE HAD A GOOD HANDLE ON THE SHOWERS
AND THUS THE FORECAST PRECIPITATION CHANCES ARE CLOSE TO IT. THERE
MAY NOT BE MUCH RAIN...GIVEN WEAK FORCING...BUT RAIN NONETHELESS.
BEST CHANCES ARE THIS MORNING OVER THE EASTERN TWO THIRDS OF THE
AREA. SKIES LOOK TO STAY CLOUDY THROUGH MUCH OF THE DAY TODAY...
WITH PERHAPS SOME CLEARING COMING IN WESTERN SECTIONS DURING THE
AFTERNOON AS SUBSIDENCE ALONG WITH DRIER AIR FROM THE DAKOTAS
BEGIN TO ADVECT IN. A BETTER CLEARING TREND IS EXPECTED TONIGHT...
ESPECIALLY AFTER MIDNIGHT...ONCE THAT NEXT SHORTWAVE TROUGH MOVES
IN. APPEARS TO BE SOME PRETTY STRONG SUBSIDENCE AND DRYING IN THE
WAKE OF THAT SHORTWAVE TROUGH. ALTHOUGH THERE WILL BE PLENTY OF
CLOUDS AROUND TODAY...ADVECTION AND LIMITED INSOLATION SHOULD BE
ENOUGH FOR ALL LOCATIONS TO CLIMB INTO THE 50S. WESTERN SECTIONS
COULD EVEN REACH THE UPPER 50S GIVEN THAT THEY HAVE POTENTIAL FOR
SOME SUN. COMBINATION OF CLEARING TONIGHT AND A WEAK PRESSURE
GRADIENT SHOULD ALLOW TEMPERATURES TO FALL INTO THE 30S...
ESPECIALLY IN WESTERN SECTIONS WHERE CLEARING IS MOST LIKELY TO
OCCUR.
TUESDAY THROUGH WEDNESDAY NIGHT...THE DEEP UPPER TROUGH OFF THE
BRITISH COLUMBIA IS FORECAST BY ALL MODELS TO MOVE ACROSS THE
PACIFIC NORTHWEST AND NORTHERN U.S. ROCKIES DURING THIS PERIOD...AS
A FAIRLY POTENT SHORTWAVE TROUGH...RESULTING IN THE FORMATION OF A
LOW PRESSURE SYSTEM DOWNSTREAM IN THE NORTHERN PLAINS. AS THIS
TROUGH MOVES ACROSS...STRONG UPPER RIDGING DEVELOPS DOWNSTREAM INTO
THE FORECAST AREA BY 12Z WEDNESDAY. WITH THIS RIDGING COMES A PLUME
OF DOWNSLOPED WARM AIR OFF THE ROCKIES. INITIALLY 850MB TEMPS ARE ON
THE RELATIVELY COOL SIDE ON TUESDAY...ONLY 4-6C OR SO AT 18Z...
CAUSED BY THAT SHORTWAVE DROPPING INTO THE AREA TONIGHT. STILL...
PLENTY OF SUN THANKS TO STRONG SUBSIDENCE AND DRYING IN THE WAKE OF
THE SHORTWAVE SHOULD ALLOW FOR GOOD MIXING...WITH HIGHS CLIMBING
INTO THE UPPER 40S TO MIDDLE 50S. WINDS WILL BE LIGHT TOO WITH A
SURFACE HIGH PRESSURE RIDGE CROSSING. COULD SEE A DECENT TEMPERATURE
DROP TUESDAY EVENING WITH FAVORABLE RADIATIONAL COOLING CONDITIONS
IN PLACE...ESPECIALLY ACROSS WISCONSIN WHERE THE RIDGE LINGERS
LONGEST. THE SOUTHERLY WINDS THEN PICK UP AFTER MIDNIGHT AND
ESPECIALLY FOR WEDNESDAY INTO WEDNESDAY NIGHT AS THE PRESSURE
GRADIENT TIGHTENS. 850MB TEMPS RESPOND BY WARMING TO AT LEAST 9-12C
PER MODEL CONSENSUS...OR CLOSE TO 2 STANDARD DEVIATIONS ABOVE
NORMAL. 925MB TEMPS ARE SIMILAR TO THOSE AT 850MB. SUBSIDENCE AND
DRY AIR ASSOCIATED WITH THE UPPER RIDGE WILL ALLOW FOR SUNNY
SKIES...SO CONDITIONS ARE FAVORABLE FOR MIXING. BIGGEST QUESTION
MARK IS CAN WE MIX TO 925MB. 00Z GFS/NAM SOUNDINGS SAY THE BEST WE
CAN DO IN OUR AREA IS 950MB...WHILE FARTHER WEST SAY IN SOUTH
CENTRAL AND SOUTHWEST MINNESOTA...MIXING ENDS UP BEING TO 925-900MB.
THE CAUSE FOR THE DIFFERENCE IN MIXING IS DUE TO HOW COLD WE GET
TUESDAY NIGHT. THINK THE NAM IS TOO COLD...PLUS THE WINDS PICKING UP
AFTER MIDNIGHT ESPECIALLY IN SOUTHEAST MINNESOTA MAY EVEN CAUSE
TEMPERATURES TO CLIMB. THE GFS LOOKS A LITTLE MORE REPRESENTATIVE
AND THUS IS A LITTLE WARMER THAN THE NAM FOR HIGHS. FOR NOW HAVE
LEFT THE PREVIOUS FORECAST HIGHS ALONE...THOUGH IT IS POSSIBLE THEY
NEED TO BE LOWERED. IN ANY EVENT...WEDNESDAY NIGHT LOOKS MILD
WITH THE AREA IN THE WARM SECTOR AND A PERSISTENT SOUTHERLY BREEZE
HELPING TO HOLD TEMPERATURES UP. STAYED TOWARDS THE WARM SIDE OF
GUIDANCE FOR LOWS.
.LONG TERM...THANKSGIVING THROUGH SUNDAY NIGHT
200 AM CST MON NOV 19 2012
MAIN HEADLINE HERE IS THE DRAMATIC TEMPERATURE FALL POSSIBLE
BETWEEN THANKSGIVING AND FRIDAY.
19.00Z ECMWF/CANADIAN/UKMET/GFS AND GFS ENSEMBLES ARE IN MUCH BETTER
AGREEMENT THAN YESTERDAY. ALL MODELS NOW HAVE THAT POTENT TROUGH
DIGGING INTO OUR REGION FOR THURSDAY NIGHT INTO FRIDAY...BRINGING
WITH IT A PORTION OF COLD CANADIAN AIR THAT HAS BEEN BUILDING UP IN
THE YUKON TERRITORY. THE POTENT TROUGH IS VERY PROGRESSIVE...DUE TO
NEW TROUGHING DEVELOPING OVER THE PACIFIC NORTHWEST BY THE END OF
THE WEEKEND...PUSHING UPPER RIDGING TOWARDS THE AREA. NOTE THAT THE
19.00Z GUIDANCE SUGGESTS THIS UPPER RIDGING IS FLATTER...THUS THE
WARM UP IS NOT AS INTENSE AS WHAT THE 18.12Z ECMWF SUGGESTED. PLENTY
OF TIME FOR THIS CHANGE ONE WAY OR THE OTHER OVER THE NEXT FEW
DAYS...THOUGH.
THE BIGGEST ISSUE WITH THE UPPER TROUGH ENTERING THE AREA EARLY IN
THE PERIOD IS TIMING OF THE MAIN COLD FRONT WITH IT...WITH THE
UKMET/GFS FASTER THAN THE CANADIAN/ECMWF. AT 00Z FRIDAY...THE FORMER
HAS THE FRONT THROUGH THE AREA WHILE THE LATTER HAS THE FRONT COMING
INTO WESTERN SECTIONS OF THE AREA. THIS HAS SIGNIFICANT IMPLICATIONS
ON TEMPERATURES FOR THANKSGIVING DAY...GIVEN THAT READINGS WILL
START OFF MUCH WARMER THAN THOSE ON TUESDAY NIGHT...THUS ALLOWING
FOR BETTER MIXING POTENTIAL. PLUS...925MB TEMPS MAY NOT COOL MUCH
UNTIL LATE IN THE DAY. FOR NOW HAVE STAYED CLOSE TO THE PREVIOUS
FORECAST FOR HIGHS UNTIL THE FRONTAL TIMING CAN BE IRONED OUT.
ONE OTHER ISSUE FOR THANKSGIVING DAY IS THAT THE GFS/CANADIAN
PRODUCE QPF OVER THE SOUTHEAST HALF OF THE FORECAST AREA. THIS QPF
IS RELATED TO A SUBTROPICAL SHORTWAVE EJECTING OUT OF AN UPPER LOW
CROSSING NORTHERN MEXICO ON WEDNESDAY. EVERY MODEL SUGGESTS A PLUME
OF HIGHER MOISTURE STREAMING UP INTO THE FORECAST AREA ON
THANKSGIVING...AHEAD OF THE WARM FRONT...NOTED BY 850MB DEWPOINTS
CLIMBING TO 4C OR SO. NEW 19.00Z ECMWF NOW PRODUCES QPF TOO BY
BRINGING THAT SHORTWAVE UP...THOUGH LIGHTER AND OUTSIDE FOR THE
FORECAST AREA. WITH GOOD AGREEMENT ON THE SHORTWAVE COMING UP
THROUGH THE MOISTURE STREAM...KEPT THE CONSENSUS APPROACH ADDITION
OF 20 PERCENT CHANCES FOR THE SOUTHEAST HALF ON THANKSGIVING.
AFTER THE MAIN FRONTAL PASSAGE...ATTENTION TURNS TO WINDS AND
TEMPERATURES AS COLD AIR FILTERS IN. IT APPEARS THE COLDEST AIR
WAITS UNTIL FRIDAY...ASSOCIATED WITH A SECONDARY COLD FRONTAL
PASSAGE. FOR EXAMPLE...850MB TEMPS AT 06Z FRIDAY ARE GENERALLY IN
THE RANGE OF -3C WEST TO 1C EAST. BY 18Z FRIDAY...EVERYONE IS SEEING
850MB TEMPS BETWEEN -10 AND -13C. THUS...TEMPERATURES PROBABLY ARE
NOT GOING TO RISE MUCH ABOVE MORNING LOWS...AND IF ANYTHING POSSIBLY
FALL. GOOD MIXING SETUP TOO GIVING COLD ADVECTION DURING THE DAYTIME
AND UNIDIRECTIONAL LOW LEVEL WINDS. SUSTAINED 15-20 KT WINDS LOOK
REASONABLE WITH GUSTS OF 30-35 KT AT LEAST WEST OF THE MISSISSIPPI
RIVER.
THINGS CALM DOWN FOR FRIDAY NIGHT AND THE WEEKEND AS A RIDGE OF HIGH
PRESSURE CROSSES THE AREA AND BEGINS A WARM UP.
&&
.AVIATION...THROUGH 18Z TUESDAY
1156 AM CST MON NOV 19 2012
CURRENTLY WATCHING A MID-LEVEL TROUGH AND WEAK SURFACE COLD FRONT
MOVING THROUGH THE REGION. MOST OF THE SCATTERED RAIN SHOWER
ACTIVITY TIED TO THIS MID-LEVEL TROUGH AND FRONT WAS NOW OVER
CENTRAL AND EASTERN WI WITH MID-CLOUD LINGERING ACROSS THE REST OF
THE AREA. SIGNAL IS SHOWING UP TONIGHT FOR STRATUS/FOG POTENTIAL
GIVEN WEAK PRESSURE GRADIENT/LIGHT WINDS AND FAIRLY MOIST LOWER
BOUNDARY LAYER FROM TODAYS SCATTERED RAINFALL. HAVE INCLUDED IFR
STRATUS AT KLSE FROM 06-09Z. NOT AS CONFIDENT AT KRST THOUGH WHERE
LIGHT NORTHWEST WINDS AFTER 06Z AND LACK OF RAINFALL/DRIER LOWER
BOUNDARY LAYER MAY PREVENT WIDESPREAD DEVELOPMENT. THIS WILL HAVE
TO BE MONITORED CLOSELY. LOOKING FOR IMPROVING/VFR CONDITIONS BY
LATE TUESDAY MORNING AS DRIER AIR SPREADS INTO THE AREA.
&&
.CLIMATE...
200 AM CST SUN NOV 18 2012
RECORD HIGH TEMPERATURES FOR WEDNESDAY/21ST AND THURSDAY/22ND. COOP
SITES ARE 6AM-6AM HIGHS...THUS 22ND HIGHS ARE 21.12Z TO 22.12Z. LA
CROSSE AND ROCHESTER ARE ONLY NON-COOP SITES.
FORECAST HIGH TEMPERATURES SUGGEST SOME OF THE RECORDS BELOW MAY
BE TIED OR BROKEN.
LOCATION WEDNESDAY/21ST THURSDAY/22ND
LA CROSSE WI 72/1990 59/1963
SPARTA WI 65/1990 70/1990
MEDFORD WI 59/1913 65/1990
LANCASTER WI 66/2003 66/1898
MAUSTON WI 67/2003 66/1990
ROCHESTER MN 69/1990 65/1913
AUSTIN MN 70/1990 58/1966
WINONA DAM 5A MN 60/2003 60/2001
WABASHA MN 61/1908 59/1908
CHARLES CITY IA 71/1990 62/1966
OELWEIN IA 71/1990 62/1966
DECORAH IA 71/1990 62/1908
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
200 AM CST MON NOV 19 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...DAS
CLIMATE......JONES/DB/AJ
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1025 AM CST MON NOV 19 2012
.UPDATE...MAIN CONCERNS TODAY ARE WX/POPS AND TEMPERATURES. S/W
TROUGH IS EVIDENT IN THE WV LOOP PUSHING THROUGH NORTHERN KS. VIS
SAT SHOWING OVERCAST SKIES WITH A FEW BREAKS...PRETTY RAGGED CLOUD
ELEMENTS. SFC MAP IS SHOWING CLOUD BASES AROUND 100 HFT...WITH
ONLY LONE ROCK IN S WI WITH A REPORT OF PRECIP...WITH A TRACE.
KMKX RADAR AND MOSAIC SHOWING LIGHT RETURNS ACROSS PORTIONS OF THE
WEST HALF OF CENTRAL AND SOUTHERN WI...THAT ARE GENERALLY AROUND
15-20 DBZ WITH HIGHER VALUES IN THE MID 20S TO 30S IN THE FAR NW
OF THE CWA AND OUTSIDE THE CWA. UPSTREAM AND SOUTH IN WESTERN
IL...RADAR RETURNS ARE STRONGER...AND ARE LIKELY WHAT COULD BE THE
BEST CHANCE FOR MEASURABLE PRECIP LATER TODAY.
WITH THE HIGH CLOUD BASES AND DRY AIR IN PLACE...THE LATTER VERY
NOTICEABLE FROM 850 HPA ISODROSOTHERM ANALYSES AND BUFKIT MODEL
SOUNDINGS...MOST OF THE RETURNS ARE LIKELY ASSOCIATED WITH VIRGA
INSTEAD OF PRECIP. 12 UTC DVN SOUNDING PROVIDES FURTHER EVIDENCE OF
THE DRY AIR IN PLACE...WITH DRY AIR/LOW RH IN PLACE FROM 700 HPA ON
DOWN AND PWAT OF .39 INCHES.
850-300 HPA MEAN FLOW IS OUT OF THE SOUTHWEST...WITH THE CURRENT
TRACK OF PRECIP UPSTREAM APPEARING TO BE HEADING FOR SOUTH OF
MADISON AND MORE TOWARDS THE SE OF THE CWA. LATEST HI-RES MODEL
REFLECTIVITY FIELDS...LOCAL WRF AND HRRR...ALTHOUGH MATCH WELL WITH
REFLECTIVITY UPSTREAM...NOT SO MUCH WITH WHATS OCCURRING IN THE
CWA. HRRR DEPICTS SHOWERY AND VERY LIGHT PRECIP BEGINNING THIS
AFTERNOON WITH A BREAK OCCURRING NOW UNTIL THEN...AFTER 21 UTC. THIS
COINCIDES WELL WITH CURRENT THINKING...AFTER LOOKING AT THE LATEST
RADAR TRENDS AND MODEL SOUNDINGS. THUS LOWERED POPS THIS AFTERNOON
TILL 21 UTC...WITH THE MAIN ISSUE WHETHER TO GO WITH DRIZZLE MENTION
WITH A SLIGHT CHANCE OF MEASURABLE PRECIP AT THE MOMENT.
HIGHS WERE LEFT AS IS. WILL BE TRICKY...IF SOME SUN CAN BREAK
THROUGH/HOLES APPEAR. NOT MUCH CONFIDENCE AT THE MOMENT. SO LEFT AS
IS AND WILL WAIT A BIT MORE TO ASSESS SKY AND TEMP TRENDS.
&&
.AVIATION/18Z TAFS/...MAY SEE A SHOWER OR SPRINKLE THROUGH THE
REMAINDER OF THE DAY...BUT OTHERWISE WILL JUST BE BKN TO OVC MID
AND HIGH LEVEL CLOUDS. WILL SEE AN INCREASE IN LOW LEVEL MOISTURE
LATE AFTERNOON AND EVENING...SO SOME MVFR CIGS POSSIBLE FOR A TIME
AFTER 00Z. WILL CONSIDER ADDING INTO NEXT TAF PACKAGE. COULD BE A
FEW SHOWERS/SPRINKLES TONIGHT TOO...OR MAYBE DRIZZLE. SOUNDINGS
GET PRETTY SATURATED IN THE LOWEST LEVELS AFTER MIDNIGHT...SO MAY
SEE SOME LOWER VSBYS AS WELL. WILL AT LEAST MAINTAIN MVFR VSBYS
IN TAFS AND CONSIDER GOING LOWER.
MODEL SOUNDINGS AND TIME HEIGHTS SHOW THAT DRIER AIR WILL BE SLOW
TO MOVE IN TOMORROW...SO COULD HOLD ONTO SOME LOWER CIGS THROUGH
AT LEAST THE MORNING...MAYBE EVEN THE AFTERNOON IN THE EAST.
&&
.PREV DISCUSSION... /ISSUED 330 AM CST MON NOV 19 2012/
TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM TO HIGH
COOLEST CLOUD TOPS OVER CENTRAL IOWA INTO NRN MO ON IR SATELLITE
LOOPS IN REGION OF BEST LIFT AHEAD OF SHORT WAVE OVER ERN
NEB/KS...THAT MODELS WEAKEN ALONG WITH THE 250 MB JET-LET DRIVING
THIS VORT AS IT LIFTS TO THE NORTHEAST. PLENTY OF SCATTERED LIGHT
RETURNS OVER SW WI AND WRN IL ON REGIONAL RADARS...BUT MAINLY TIED
TO ISENTROPIC LIFT AT/ABOVE 700 MB WITH NO SURFACE REPORTS UNDER
7K TO 10K FT CEILINGS. INITIAL ISENTROPIC LIFT ONLY SATURATES
COLUMN DOWN TO AROUND 700 MB...WITH DRY AIR HOLDING IN BELOW INTO
THE EARLY AFTERNOON PER MODEL FORECAST SOUNDINGS AND TIGHT 850 MB
DEW POINT GRADIENT ON MODELS OVER CENTRAL WI AT 18Z.
LOCATIONS CURRENTLY REPORTING PRECIPITATION AT THE SURFACE FARTHER
TO THE SOUTHWEST IN LINE WITH NARROW CHANNEL OF DEEPER MOISTURE
AND STRONGER 700 MB OMEGA WITH BETTER LAYER Q-VECTOR CONVERGENCE
AHEAD OF DEVELOPING BROAD MID LEVEL TROUGH THAT CROSSES SOUTHERN
WI TODAY INTO THIS EVENING....WITH BEST LIFT EAST OF THE STATE
AROUND 06Z TUE ON EASTERN FLANK OF BROAD MID-LEVEL TROUGH.
THUS MOST OF SOUTHERN WI CLOUDY BUT DRY THROUGH THE
MORNING...EXCEPT IN THE FAR WEST WHICH RAPID UPDATE/HI RES MODELS
CLIP WITH CURRENT BAND OF SHOWERS IN EASTERN IOWA WHERE BETTER
LAYER FRONTOGENETIC FORCING LIFTS THROUGH FROM SOUTHWEST TO
NORTHWEST THIS MORNING INTO EARLY THIS AFTERNOON.
WILL TIME GENERALLY ISOLATED LIGHT RAIN SHOWERS/SCATTERED
SPRINKLES WITH LAYER Q-VECTOR CONVERGENCE AND 700 MB OMEGA. WILL
ALSO CARRY ISOLATED SPRINKLES AFTER MIDNIGHT IN THE FAR EAST WITH
WEAK FORCING AHEAD OF SURFACE TROUGH.
WENT WITH A CONSENSUS BLEND FOR TEMPERATURES WHICH LEAN TOWARD
PREVIOUS FORECAST...AND BETWEEN MAV/MET NUMBERS. CLOUDS AND
EVENTUAL LIGHT PRECIPITATION WILL PREVENT REACHING WARM MET
NUMBERS...BUT RELATIVELY WARM START TO THE DAY SHOULD ALLOW
SURFACE TEMPERATURES TO REACH THE MID 50S.
TUESDAY THROUGH WEDNESDAY NIGHT...FORECAST CONFIDENCE IS HIGH.
SHORT TERM MODELS SHOWING 500MB SHORTWAVE TROUGH SLIDING
SOUTHEAST ACROSS THE AREA MAINLY TUESDAY MORNING...WITH THE NAM
SLOWER AND BRINGING IT THROUGH IN THE AFTERNOON. WEAK SURFACE COLD
FRONT MOVES EAST THROUGH THE AREA TUESDAY MORNING. AREA FORECAST
SOUNDINGS SHOWING SOME MOISTURE IN THE LOWER LEVELS DURING THE
MORNING...MORE SO ON THE GFS THAN THE NAM. BOTH HAD THE MID TO
UPPER LEVELS DRY.
GIVEN THE WEAK UPWARD VERTICAL MOTION FIELDS IN THE AREA WITH
THESE FEATURES...WILL KEEP FORECAST DRY TUESDAY. HIGHS WILL REMAIN
MILD...INTO THE MID 50S PER NAM 925MB TEMPERATURES AND EXPECTED
MIXING TO THAT LEVEL.
500MB RIDGE AXIS THEN SLIDES SOUTHEAST ACROSS THE REGION TUESDAY
NIGHT AND WEDNESDAY...THEN TO THE SOUTHEAST WEDNESDAY NIGHT.
SURFACE HIGH PRESSURE SLOWLY SLIDES SOUTHEAST DURING THIS TIME AS
WELL...WITH SOUTH WINDS GRADUALLY INCREASING. PATCHY FOG IS
EXPECTED TUESDAY NIGHT...WITH LIGHT WINDS AND CLEAR SKIES WITH
RADIATIONAL COOLING.
WARM AIR ADVECTION KICKS IN TUESDAY NIGHT AND WEDNESDAY...WHICH
SHOULD BRING 925MB TEMPERATURES INTO THE 8 TO 11 DEGREE CELSIUS
RANGE PER NAM. SHOULD SEE HIGHS REACH THE UPPER 50S TO LOWER
60S...DEPENDING ON IF MIXING REACHES THE 925MB LEVEL. LOWS IN THE
30S TUESDAY NIGHT SHOULD WARM INTO THE LOWER TO MID 40S WEDNESDAY
NIGHT.
THANKSGIVING DAY THROUGH SUNDAY...FORECAST CONFIDENCE IS MEDIUM.
GFS/ECMWF SHOWING SOME DIFFERENCES WITH FEATURES DURING THIS
PERIOD. THE GFS AND ECMWF BOTH NOW HAVE MORE QPF ACROSS THE AREA
IN THE AFTERNOON THANKSGIVING DAY...AS A STRONG COLD FRONT MOVES
TOWARD THE AREA. THE FRONT MOVES THROUGH THE AREA THURSDAY
EVENING...AND EXITS LATER IN THE NIGHT.
A STRONG SHORTWAVE TROUGH AT 500MB THEN MOVES THROUGH THE
AREA...ABOUT 6 HOURS QUICKER ON THE GFS THAN THE ECMWF. SECONDARY
SHORTWAVE THEN MOVES SOUTHEAST THROUGH THE AREA FRIDAY ON BOTH
MODELS. ECMWF KEEPS 500MB CYCLONIC FLOW IN THE AREA FRIDAY NIGHT
INTO EARLY SATURDAY...WITH THE GFS ALREADY OUT OF THE REGION.
AREA FORECAST SOUNDINGS FROM THE GFS SHOW MODEST MOISTURE IN THE
AIR COLUMN...WITH WEAK TO MODEST UPWARD VERTICAL MOTION. FOR
NOW...WILL ADD SLIGHT CHANCE POPS FOR LIGHT RAIN SHOWERS
THANKSGIVING DAY...LINGERING IN THE FAR SOUTHEAST THURSDAY NIGHT.
MILD TEMPERATURES WILL CONTINUE THANKSGIVING DAY...BEFORE STRONG
COLD AIR ADVECTION BEHIND THE FRONT KICKS IN THURSDAY NIGHT AND
FRIDAY FROM BOTH THE GFS AND ECMWF. THIS SHOULD BRING COOLER
TEMPERATURES TO THE AREA.
THE GFS CONTINUES TO BE QUICKER WITH FEATURES THAN THE ECMWF
SATURDAY INTO SUNDAY. THE GFS HAS WARM AIR ADVECTION DEVELOPING
SATURDAY INTO SUNDAY...WITH THE ECMWF HOLDING OFF UNTIL SATURDAY
NIGHT AND SUNDAY. KEPT THIS PERIOD DRY...WITH LACK OF DEEP
MOISTURE IN GFS FORECAST SOUNDINGS ACROSS THE AREA. COOL
TEMPERATURES SHOULD CONTINUE DURING THIS TIME.
AVIATION/12Z TAFS/...EXPECT VFR CIGS AND VSBYS FOR MOST OF THE
PERIOD...WITH BIGGEST QUESTION HOW HARD TO HIT PRECIPITATION.
INITIALLY...BEST CHANCE TO SEE PRECIP WILL BE AT KMSN AROUND MID-
MORNING IF CURRENT BAND OF SHOWERS IN EASTERN IOWA HOLDS TOGETHER.
MOST OF THE RAPID UPDATE MODELS KILL THIS PRECIP OFF...WITH WIDELY
SCATTERED LIGHT SHOWERS/SPRINKLES AHEAD OF MID-LEVEL TROUGH THIS
AFTERNOON AND EVENING. WILL KEEP VICINITY SHOWERS FOR MOST LIKELY
PERIODS...WITH VFR CIGS AND VSBYS. MAV GUIDANCE WANTS TO LOWER
CIGS TO MVFR BEHIND THE SURFACE TROUGH...WITH NAM INDICATING SOME
POTENTIAL FOR MVFR VSBYS IN FOG. WILL LEAVE OUT FOR NOW AND AWAIT
UPSTREAM INDICATORS.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...ET/DDV
TODAY/TONIGHT AND AVIATION/MARINE...REM
TUESDAY THROUGH SUNDAY...WOOD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
550 AM CST MON NOV 19 2012
.SHORT TERM...THROUGH WEDNESDAY NIGHT
200 AM CST MON NOV 19 2012
MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES TODAY AND HOW
WARM WE WILL GET ON WEDNESDAY.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A DEEP TROUGH JUST OFF BRITISH COLUMBIA...THEN A
WEST-SOUTHWEST FLOW FROM CALIFORNIA INTO THE WESTERN GREAT LAKES
REGION. WITHIN THIS FLOW...A WEAK SHORTWAVE TROUGH STRETCHED FROM
WESTERN IOWA INTO CENTRAL KANSAS. AHEAD OF THIS SHORTWAVE TROUGH...A
PLUME OF PRECIPITABLE WATER VALUES OF 0.75 INCHES OR SO CAN BE SEEN
ON GOES DERIVED IMAGERY...STREAMING NORTH FROM OKLAHOMA INTO NORTH
CENTRAL IOWA. PROFILER AND VWP DATA SHOWED 850MB WINDS OF 30-40 KT
WITHIN THIS PLUME OF MOISTURE...HELPING TO ADVECT IT NORTHEAST
TOWARDS THE FORECAST AREA. THE COMBINATION OF THIS MOISTURE
TRANSPORT AND WEAK DPVA AHEAD OF THE SHORTWAVE TROUGH HAS BEEN
SUPPORTING A BAND OF SHOWERS JUST EAST OF I-35 IN IOWA. IN
ADDITION TO THE ADVECTION OF MOISTURE...THE WINDS AS WELL AS
CLOUDS ARE HELPING TO KEEP TEMPERATURES UP IN THE 40S AND EVEN
AROUND 50 AT SOME LOCATIONS. LAST ITEM OF NOTE WAS ANOTHER WEAK
SHORTWAVE TROUGH OVER EASTERN MONTANA. DRIER AIR PRESENT OVER THE
NORTHERN PLAINS...AS SEEN ON THE 00Z BIS AND GGW SOUNDINGS...HAS
KEPT ANY CLOUD COVER TO SCATTERED HIGH BASED ALTOSTRATUS AND
CIRRUS WITH THIS SHORTWAVE TROUGH.
TODAY AND TONIGHT...THE SHORTWAVE TROUGH JUST OFF TO OUR SOUTHWEST
IS PROGGED TO LIFT NORTHEAST AND MOVE THROUGH MUCH OF THE FORECAST
AREA BY 21Z TODAY. MEANWHILE...THAT NEXT SHORTWAVE TROUGH OVER
MONTANA LOOKS TO DROP DOWN INTO THE FORECAST AREA AFTER 06Z TONIGHT
IN THE WAKE OF THE FIRST TROUGH. MOST OF THE FOCUS IS ON THE
SHORTWAVE TROUGH TODAY AS IT HAS THE MOST MOISTURE TO WORK WITH.
PRECIPITABLE WATER FORECASTS SHOW THE AREA OF MOISTURE IN CENTRAL
IOWA SPREADING NORTHEAST THROUGH THE FORECAST AREA...THEN SLOWLY
SHIFTING EAST THIS AFTERNOON THROUGH TONIGHT AS THE SHORTWAVE TROUGH
EXITS THE FORECAST AREA. SEEING THAT THE WEAK DPVA AND ISENTROPIC
LIFT HAS BEEN ABLE TO PRODUCE THE BAND OF SHOWERS NEAR I-35 IN
IOWA...FEEL CONFIDENT THAT SHOWERS WILL AFFECT THE FORECAST AREA
TODAY. HRRR RUNS SINCE 19.01Z HAVE HAD A GOOD HANDLE ON THE SHOWERS
AND THUS THE FORECAST PRECIPITATION CHANCES ARE CLOSE TO IT. THERE
MAY NOT BE MUCH RAIN...GIVEN WEAK FORCING...BUT RAIN NONETHELESS.
BEST CHANCES ARE THIS MORNING OVER THE EASTERN TWO THIRDS OF THE
AREA. SKIES LOOK TO STAY CLOUDY THROUGH MUCH OF THE DAY TODAY...
WITH PERHAPS SOME CLEARING COMING IN WESTERN SECTIONS DURING THE
AFTERNOON AS SUBSIDENCE ALONG WITH DRIER AIR FROM THE DAKOTAS
BEGIN TO ADVECT IN. A BETTER CLEARING TREND IS EXPECTED TONIGHT...
ESPECIALLY AFTER MIDNIGHT...ONCE THAT NEXT SHORTWAVE TROUGH MOVES
IN. APPEARS TO BE SOME PRETTY STRONG SUBSIDENCE AND DRYING IN THE
WAKE OF THAT SHORTWAVE TROUGH. ALTHOUGH THERE WILL BE PLENTY OF
CLOUDS AROUND TODAY...ADVECTION AND LIMITED INSOLATION SHOULD BE
ENOUGH FOR ALL LOCATIONS TO CLIMB INTO THE 50S. WESTERN SECTIONS
COULD EVEN REACH THE UPPER 50S GIVEN THAT THEY HAVE POTENTIAL FOR
SOME SUN. COMBINATION OF CLEARING TONIGHT AND A WEAK PRESSURE
GRADIENT SHOULD ALLOW TEMPERATURES TO FALL INTO THE 30S...
ESPECIALLY IN WESTERN SECTIONS WHERE CLEARING IS MOST LIKELY TO
OCCUR.
TUESDAY THROUGH WEDNESDAY NIGHT...THE DEEP UPPER TROUGH OFF THE
BRITISH COLUMBIA IS FORECAST BY ALL MODELS TO MOVE ACROSS THE
PACIFIC NORTHWEST AND NORTHERN U.S. ROCKIES DURING THIS PERIOD...AS
A FAIRLY POTENT SHORTWAVE TROUGH...RESULTING IN THE FORMATION OF A
LOW PRESSURE SYSTEM DOWNSTREAM IN THE NORTHERN PLAINS. AS THIS
TROUGH MOVES ACROSS...STRONG UPPER RIDGING DEVELOPS DOWNSTREAM INTO
THE FORECAST AREA BY 12Z WEDNESDAY. WITH THIS RIDGING COMES A PLUME
OF DOWNSLOPED WARM AIR OFF THE ROCKIES. INITIALLY 850MB TEMPS ARE ON
THE RELATIVELY COOL SIDE ON TUESDAY...ONLY 4-6C OR SO AT 18Z...
CAUSED BY THAT SHORTWAVE DROPPING INTO THE AREA TONIGHT. STILL...
PLENTY OF SUN THANKS TO STRONG SUBSIDENCE AND DRYING IN THE WAKE OF
THE SHORTWAVE SHOULD ALLOW FOR GOOD MIXING...WITH HIGHS CLIMBING
INTO THE UPPER 40S TO MIDDLE 50S. WINDS WILL BE LIGHT TOO WITH A
SURFACE HIGH PRESSURE RIDGE CROSSING. COULD SEE A DECENT TEMPERATURE
DROP TUESDAY EVENING WITH FAVORABLE RADIATIONAL COOLING CONDITIONS
IN PLACE...ESPECIALLY ACROSS WISCONSIN WHERE THE RIDGE LINGERS
LONGEST. THE SOUTHERLY WINDS THEN PICK UP AFTER MIDNIGHT AND
ESPECIALLY FOR WEDNESDAY INTO WEDNESDAY NIGHT AS THE PRESSURE
GRADIENT TIGHTENS. 850MB TEMPS RESPOND BY WARMING TO AT LEAST 9-12C
PER MODEL CONSENSUS...OR CLOSE TO 2 STANDARD DEVIATIONS ABOVE
NORMAL. 925MB TEMPS ARE SIMILAR TO THOSE AT 850MB. SUBSIDENCE AND
DRY AIR ASSOCIATED WITH THE UPPER RIDGE WILL ALLOW FOR SUNNY
SKIES...SO CONDITIONS ARE FAVORABLE FOR MIXING. BIGGEST QUESTION
MARK IS CAN WE MIX TO 925MB. 00Z GFS/NAM SOUNDINGS SAY THE BEST WE
CAN DO IN OUR AREA IS 950MB...WHILE FARTHER WEST SAY IN SOUTH
CENTRAL AND SOUTHWEST MINNESOTA...MIXING ENDS UP BEING TO 925-900MB.
THE CAUSE FOR THE DIFFERENCE IN MIXING IS DUE TO HOW COLD WE GET
TUESDAY NIGHT. THINK THE NAM IS TOO COLD...PLUS THE WINDS PICKING UP
AFTER MIDNIGHT ESPECIALLY IN SOUTHEAST MINNESOTA MAY EVEN CAUSE
TEMPERATURES TO CLIMB. THE GFS LOOKS A LITTLE MORE REPRESENTATIVE
AND THUS IS A LITTLE WARMER THAN THE NAM FOR HIGHS. FOR NOW HAVE
LEFT THE PREVIOUS FORECAST HIGHS ALONE...THOUGH IT IS POSSIBLE THEY
NEED TO BE LOWERED. IN ANY EVENT...WEDNESDAY NIGHT LOOKS MILD
WITH THE AREA IN THE WARM SECTOR AND A PERSISTENT SOUTHERLY BREEZE
HELPING TO HOLD TEMPERATURES UP. STAYED TOWARDS THE WARM SIDE OF
GUIDANCE FOR LOWS.
.LONG TERM...THANKSGIVING THROUGH SUNDAY NIGHT
200 AM CST MON NOV 19 2012
MAIN HEADLINE HERE IS THE DRAMATIC TEMPERATURE FALL POSSIBLE
BETWEEN THANKSGIVING AND FRIDAY.
19.00Z ECMWF/CANADIAN/UKMET/GFS AND GFS ENSEMBLES ARE IN MUCH BETTER
AGREEMENT THAN YESTERDAY. ALL MODELS NOW HAVE THAT POTENT TROUGH
DIGGING INTO OUR REGION FOR THURSDAY NIGHT INTO FRIDAY...BRINGING
WITH IT A PORTION OF COLD CANADIAN AIR THAT HAS BEEN BUILDING UP IN
THE YUKON TERRITORY. THE POTENT TROUGH IS VERY PROGRESSIVE...DUE TO
NEW TROUGHING DEVELOPING OVER THE PACIFIC NORTHWEST BY THE END OF
THE WEEKEND...PUSHING UPPER RIDGING TOWARDS THE AREA. NOTE THAT THE
19.00Z GUIDANCE SUGGESTS THIS UPPER RIDGING IS FLATTER...THUS THE
WARM UP IS NOT AS INTENSE AS WHAT THE 18.12Z ECMWF SUGGESTED. PLENTY
OF TIME FOR THIS CHANGE ONE WAY OR THE OTHER OVER THE NEXT FEW
DAYS...THOUGH.
THE BIGGEST ISSUE WITH THE UPPER TROUGH ENTERING THE AREA EARLY IN
THE PERIOD IS TIMING OF THE MAIN COLD FRONT WITH IT...WITH THE
UKMET/GFS FASTER THAN THE CANADIAN/ECMWF. AT 00Z FRIDAY...THE FORMER
HAS THE FRONT THROUGH THE AREA WHILE THE LATTER HAS THE FRONT COMING
INTO WESTERN SECTIONS OF THE AREA. THIS HAS SIGNIFICANT IMPLICATIONS
ON TEMPERATURES FOR THANKSGIVING DAY...GIVEN THAT READINGS WILL
START OFF MUCH WARMER THAN THOSE ON TUESDAY NIGHT...THUS ALLOWING
FOR BETTER MIXING POTENTIAL. PLUS...925MB TEMPS MAY NOT COOL MUCH
UNTIL LATE IN THE DAY. FOR NOW HAVE STAYED CLOSE TO THE PREVIOUS
FORECAST FOR HIGHS UNTIL THE FRONTAL TIMING CAN BE IRONED OUT.
ONE OTHER ISSUE FOR THANKSGIVING DAY IS THAT THE GFS/CANADIAN
PRODUCE QPF OVER THE SOUTHEAST HALF OF THE FORECAST AREA. THIS QPF
IS RELATED TO A SUBTROPICAL SHORTWAVE EJECTING OUT OF AN UPPER LOW
CROSSING NORTHERN MEXICO ON WEDNESDAY. EVERY MODEL SUGGESTS A PLUME
OF HIGHER MOISTURE STREAMING UP INTO THE FORECAST AREA ON
THANKSGIVING...AHEAD OF THE WARM FRONT...NOTED BY 850MB DEWPOINTS
CLIMBING TO 4C OR SO. NEW 19.00Z ECMWF NOW PRODUCES QPF TOO BY
BRINGING THAT SHORTWAVE UP...THOUGH LIGHTER AND OUTSIDE FOR THE
FORECAST AREA. WITH GOOD AGREEMENT ON THE SHORTWAVE COMING UP
THROUGH THE MOISTURE STREAM...KEPT THE CONSENSUS APPROACH ADDITION
OF 20 PERCENT CHANCES FOR THE SOUTHEAST HALF ON THANKSGIVING.
AFTER THE MAIN FRONTAL PASSAGE...ATTENTION TURNS TO WINDS AND
TEMPERATURES AS COLD AIR FILTERS IN. IT APPEARS THE COLDEST AIR
WAITS UNTIL FRIDAY...ASSOCIATED WITH A SECONDARY COLD FRONTAL
PASSAGE. FOR EXAMPLE...850MB TEMPS AT 06Z FRIDAY ARE GENERALLY IN
THE RANGE OF -3C WEST TO 1C EAST. BY 18Z FRIDAY...EVERYONE IS SEEING
850MB TEMPS BETWEEN -10 AND -13C. THUS...TEMPERATURES PROBABLY ARE
NOT GOING TO RISE MUCH ABOVE MORNING LOWS...AND IF ANYTHING POSSIBLY
FALL. GOOD MIXING SETUP TOO GIVING COLD ADVECTION DURING THE DAYTIME
AND UNIDIRECTIONAL LOW LEVEL WINDS. SUSTAINED 15-20 KT WINDS LOOK
REASONABLE WITH GUSTS OF 30-35 KT AT LEAST WEST OF THE MISSISSIPPI
RIVER.
THINGS CALM DOWN FOR FRIDAY NIGHT AND THE WEEKEND AS A RIDGE OF HIGH
PRESSURE CROSSES THE AREA AND BEGINS A WARM UP.
&&
.AVIATION...TODAY AND TONIGHT
545 AM CST MON NOV 19 2012
WATER VAPOR IMAGERY SHOWING A SHORT WAVE MOVING THROUGH NORTHEAST
IOWA. THIS SYSTEM WILL PRODUCE SHOWERS IN THE KLSE AREA THROUGH
19.15Z. IN ITS WAKE...EXPECT CEILINGS TO REMAIN AROUND 5K FEET FOR
THE REMAINDER OF THIS MORNING.
FOR THIS AFTERNOON AND TONIGHT...THE MAIN CONCERN WILL BE THE
CLOUD COVER. THE INFRARED SATELLITE SHOWS SOME CLEARING IN THE
WAKE OF THIS SHORTWAVE. IF IT CONTINUES ON CURRENT SPEED...THE
CLEARING WOULD REACH KRST AROUND 19.18Z AND KLSE AROUND 19.21Z.
WITH ALL OF DETERMINISTIC MODELS INSISTENT THAT THE CLOUDS WILL
REMAIN ACROSS THE AREA THROUGH THE NIGHT...DECIDED TO COMPROMISE A
BIT AND HAVE THE CLEARING TAKE PLACE AT KRST AROUND 20.00Z AND AT
KLSE AROUND 20.03Z.
FOR LATE TONIGHT...THE MODELS SHOW THAT A COLD FRONT WILL MOVE
THROUGH THE AREA. THIS FRONT WILL SHIFT THE WINDS FROM THE SOUTH
TO WEST. IN ADDITION...THE MODELS ARE INSISTENT THAT THERE WILL BE
MVFR CEILINGS IN ITS WAKE. THE MODELS SEEM TO BE OVERDOING THESE
CLOUDS...BECAUSE THERE ARE NO LOW CLOUDS ANYWHERE ACROSS THE
DAKOTAS. DUE TO THIS...JUST WENT WITH A SCATTERED DECK OF CLOUDS.
&&
.CLIMATE...
200 AM CST SUN NOV 18 2012
RECORD HIGH TEMPERATURES FOR WEDNESDAY/21ST AND THURSDAY/22ND. COOP
SITES ARE 6AM-6AM HIGHS...THUS 22ND HIGHS ARE 21.12Z TO 22.12Z. LA
CROSSE AND ROCHESTER ARE ONLY NON-COOP SITES.
FORECAST HIGH TEMPERATURES SUGGEST SOME OF THE RECORDS BELOW MAY
BE TIED OR BROKEN.
LOCATION WEDNESDAY/21ST THURSDAY/22ND
LA CROSSE WI 72/1990 59/1963
SPARTA WI 65/1990 70/1990
MEDFORD WI 59/1913 65/1990
LANCASTER WI 66/2003 66/1898
MAUSTON WI 67/2003 66/1990
ROCHESTER MN 69/1990 65/1913
AUSTIN MN 70/1990 58/1966
WINONA DAM 5A MN 60/2003 60/2001
WABASHA MN 61/1908 59/1908
CHARLES CITY IA 71/1990 62/1966
OELWEIN IA 71/1990 62/1966
DECORAH IA 71/1990 62/1908
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
200 AM CST MON NOV 19 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
CLIMATE......JONES/DB/AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
200 AM CST MON NOV 19 2012
.SHORT TERM...THROUGH WEDNESDAY NIGHT
200 AM CST MON NOV 19 2012
MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES TODAY AND HOW
WARM WE WILL GET ON WEDNESDAY.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A DEEP TROUGH JUST OFF BRITISH COLUMBIA...THEN A
WEST-SOUTHWEST FLOW FROM CALIFORNIA INTO THE WESTERN GREAT LAKES
REGION. WITHIN THIS FLOW...A WEAK SHORTWAVE TROUGH STRETCHED FROM
WESTERN IOWA INTO CENTRAL KANSAS. AHEAD OF THIS SHORTWAVE TROUGH...A
PLUME OF PRECIPITABLE WATER VALUES OF 0.75 INCHES OR SO CAN BE SEEN
ON GOES DERIVED IMAGERY...STREAMING NORTH FROM OKLAHOMA INTO NORTH
CENTRAL IOWA. PROFILER AND VWP DATA SHOWED 850MB WINDS OF 30-40 KT
WITHIN THIS PLUME OF MOISTURE...HELPING TO ADVECT IT NORTHEAST
TOWARDS THE FORECAST AREA. THE COMBINATION OF THIS MOISTURE
TRANSPORT AND WEAK DPVA AHEAD OF THE SHORTWAVE TROUGH HAS BEEN
SUPPORTING A BAND OF SHOWERS JUST EAST OF I-35 IN IOWA. IN
ADDITION TO THE ADVECTION OF MOISTURE...THE WINDS AS WELL AS
CLOUDS ARE HELPING TO KEEP TEMPERATURES UP IN THE 40S AND EVEN
AROUND 50 AT SOME LOCATIONS. LAST ITEM OF NOTE WAS ANOTHER WEAK
SHORTWAVE TROUGH OVER EASTERN MONTANA. DRIER AIR PRESENT OVER THE
NORTHERN PLAINS...AS SEEN ON THE 00Z BIS AND GGW SOUNDINGS...HAS
KEPT ANY CLOUD COVER TO SCATTERED HIGH BASED ALTOSTRATUS AND
CIRRUS WITH THIS SHORTWAVE TROUGH.
TODAY AND TONIGHT...THE SHORTWAVE TROUGH JUST OFF TO OUR SOUTHWEST
IS PROGGED TO LIFT NORTHEAST AND MOVE THROUGH MUCH OF THE FORECAST
AREA BY 21Z TODAY. MEANWHILE...THAT NEXT SHORTWAVE TROUGH OVER
MONTANA LOOKS TO DROP DOWN INTO THE FORECAST AREA AFTER 06Z TONIGHT
IN THE WAKE OF THE FIRST TROUGH. MOST OF THE FOCUS IS ON THE
SHORTWAVE TROUGH TODAY AS IT HAS THE MOST MOISTURE TO WORK WITH.
PRECIPITABLE WATER FORECASTS SHOW THE AREA OF MOISTURE IN CENTRAL
IOWA SPREADING NORTHEAST THROUGH THE FORECAST AREA...THEN SLOWLY
SHIFTING EAST THIS AFTERNOON THROUGH TONIGHT AS THE SHORTWAVE TROUGH
EXITS THE FORECAST AREA. SEEING THAT THE WEAK DPVA AND ISENTROPIC
LIFT HAS BEEN ABLE TO PRODUCE THE BAND OF SHOWERS NEAR I-35 IN
IOWA...FEEL CONFIDENT THAT SHOWERS WILL AFFECT THE FORECAST AREA
TODAY. HRRR RUNS SINCE 19.01Z HAVE HAD A GOOD HANDLE ON THE SHOWERS
AND THUS THE FORECAST PRECIPITATION CHANCES ARE CLOSE TO IT. THERE
MAY NOT BE MUCH RAIN...GIVEN WEAK FORCING...BUT RAIN NONETHELESS.
BEST CHANCES ARE THIS MORNING OVER THE EASTERN TWO THIRDS OF THE
AREA. SKIES LOOK TO STAY CLOUDY THROUGH MUCH OF THE DAY TODAY...
WITH PERHAPS SOME CLEARING COMING IN WESTERN SECTIONS DURING THE
AFTERNOON AS SUBSIDENCE ALONG WITH DRIER AIR FROM THE DAKOTAS
BEGIN TO ADVECT IN. A BETTER CLEARING TREND IS EXPECTED TONIGHT...
ESPECIALLY AFTER MIDNIGHT...ONCE THAT NEXT SHORTWAVE TROUGH MOVES
IN. APPEARS TO BE SOME PRETTY STRONG SUBSIDENCE AND DRYING IN THE
WAKE OF THAT SHORTWAVE TROUGH. ALTHOUGH THERE WILL BE PLENTY OF
CLOUDS AROUND TODAY...ADVECTION AND LIMITED INSOLATION SHOULD BE
ENOUGH FOR ALL LOCATIONS TO CLIMB INTO THE 50S. WESTERN SECTIONS
COULD EVEN REACH THE UPPER 50S GIVEN THAT THEY HAVE POTENTIAL FOR
SOME SUN. COMBINATION OF CLEARING TONIGHT AND A WEAK PRESSURE
GRADIENT SHOULD ALLOW TEMPERATURES TO FALL INTO THE 30S...
ESPECIALLY IN WESTERN SECTIONS WHERE CLEARING IS MOST LIKELY TO
OCCUR.
TUESDAY THROUGH WEDNESDAY NIGHT...THE DEEP UPPER TROUGH OFF THE
BRITISH COLUMBIA IS FORECAST BY ALL MODELS TO MOVE ACROSS THE
PACIFIC NORTHWEST AND NORTHERN U.S. ROCKIES DURING THIS PERIOD...AS
A FAIRLY POTENT SHORTWAVE TROUGH...RESULTING IN THE FORMATION OF A
LOW PRESSURE SYSTEM DOWNSTREAM IN THE NORTHERN PLAINS. AS THIS
TROUGH MOVES ACROSS...STRONG UPPER RIDGING DEVELOPS DOWNSTREAM INTO
THE FORECAST AREA BY 12Z WEDNESDAY. WITH THIS RIDGING COMES A PLUME
OF DOWNSLOPED WARM AIR OFF THE ROCKIES. INITIALLY 850MB TEMPS ARE ON
THE RELATIVELY COOL SIDE ON TUESDAY...ONLY 4-6C OR SO AT 18Z...
CAUSED BY THAT SHORTWAVE DROPPING INTO THE AREA TONIGHT. STILL...
PLENTY OF SUN THANKS TO STRONG SUBSIDENCE AND DRYING IN THE WAKE OF
THE SHORTWAVE SHOULD ALLOW FOR GOOD MIXING...WITH HIGHS CLIMBING
INTO THE UPPER 40S TO MIDDLE 50S. WINDS WILL BE LIGHT TOO WITH A
SURFACE HIGH PRESSURE RIDGE CROSSING. COULD SEE A DECENT TEMPERATURE
DROP TUESDAY EVENING WITH FAVORABLE RADIATIONAL COOLING CONDITIONS
IN PLACE...ESPECIALLY ACROSS WISCONSIN WHERE THE RIDGE LINGERS
LONGEST. THE SOUTHERLY WINDS THEN PICK UP AFTER MIDNIGHT AND
ESPECIALLY FOR WEDNESDAY INTO WEDNESDAY NIGHT AS THE PRESSURE
GRADIENT TIGHTENS. 850MB TEMPS RESPOND BY WARMING TO AT LEAST 9-12C
PER MODEL CONSENSUS...OR CLOSE TO 2 STANDARD DEVIATIONS ABOVE
NORMAL. 925MB TEMPS ARE SIMILAR TO THOSE AT 850MB. SUBSIDENCE AND
DRY AIR ASSOCIATED WITH THE UPPER RIDGE WILL ALLOW FOR SUNNY
SKIES...SO CONDITIONS ARE FAVORABLE FOR MIXING. BIGGEST QUESTION
MARK IS CAN WE MIX TO 925MB. 00Z GFS/NAM SOUNDINGS SAY THE BEST WE
CAN DO IN OUR AREA IS 950MB...WHILE FARTHER WEST SAY IN SOUTH
CENTRAL AND SOUTHWEST MINNESOTA...MIXING ENDS UP BEING TO 925-900MB.
THE CAUSE FOR THE DIFFERENCE IN MIXING IS DUE TO HOW COLD WE GET
TUESDAY NIGHT. THINK THE NAM IS TOO COLD...PLUS THE WINDS PICKING UP
AFTER MIDNIGHT ESPECIALLY IN SOUTHEAST MINNESOTA MAY EVEN CAUSE
TEMPERATURES TO CLIMB. THE GFS LOOKS A LITTLE MORE REPRESENTATIVE
AND THUS IS A LITTLE WARMER THAN THE NAM FOR HIGHS. FOR NOW HAVE
LEFT THE PREVIOUS FORECAST HIGHS ALONE...THOUGH IT IS POSSIBLE THEY
NEED TO BE LOWERED. IN ANY EVENT...WEDNESDAY NIGHT LOOKS MILD
WITH THE AREA IN THE WARM SECTOR AND A PERSISTENT SOUTHERLY BREEZE
HELPING TO HOLD TEMPERATURES UP. STAYED TOWARDS THE WARM SIDE OF
GUIDANCE FOR LOWS.
.LONG TERM...THANKSGIVING THROUGH SUNDAY NIGHT
200 AM CST MON NOV 19 2012
MAIN HEADLINE HERE IS THE DRAMATIC TEMPERATURE FALL POSSIBLE
BETWEEN THANKSGIVING AND FRIDAY.
19.00Z ECMWF/CANADIAN/UKMET/GFS AND GFS ENSEMBLES ARE IN MUCH BETTER
AGREEMENT THAN YESTERDAY. ALL MODELS NOW HAVE THAT POTENT TROUGH
DIGGING INTO OUR REGION FOR THURSDAY NIGHT INTO FRIDAY...BRINGING
WITH IT A PORTION OF COLD CANADIAN AIR THAT HAS BEEN BUILDING UP IN
THE YUKON TERRITORY. THE POTENT TROUGH IS VERY PROGRESSIVE...DUE TO
NEW TROUGHING DEVELOPING OVER THE PACIFIC NORTHWEST BY THE END OF
THE WEEKEND...PUSHING UPPER RIDGING TOWARDS THE AREA. NOTE THAT THE
19.00Z GUIDANCE SUGGESTS THIS UPPER RIDGING IS FLATTER...THUS THE
WARM UP IS NOT AS INTENSE AS WHAT THE 18.12Z ECMWF SUGGESTED. PLENTY
OF TIME FOR THIS CHANGE ONE WAY OR THE OTHER OVER THE NEXT FEW
DAYS...THOUGH.
THE BIGGEST ISSUE WITH THE UPPER TROUGH ENTERING THE AREA EARLY IN
THE PERIOD IS TIMING OF THE MAIN COLD FRONT WITH IT...WITH THE
UKMET/GFS FASTER THAN THE CANADIAN/ECMWF. AT 00Z FRIDAY...THE FORMER
HAS THE FRONT THROUGH THE AREA WHILE THE LATTER HAS THE FRONT COMING
INTO WESTERN SECTIONS OF THE AREA. THIS HAS SIGNIFICANT IMPLICATIONS
ON TEMPERATURES FOR THANKSGIVING DAY...GIVEN THAT READINGS WILL
START OFF MUCH WARMER THAN THOSE ON TUESDAY NIGHT...THUS ALLOWING
FOR BETTER MIXING POTENTIAL. PLUS...925MB TEMPS MAY NOT COOL MUCH
UNTIL LATE IN THE DAY. FOR NOW HAVE STAYED CLOSE TO THE PREVIOUS
FORECAST FOR HIGHS UNTIL THE FRONTAL TIMING CAN BE IRONED OUT.
ONE OTHER ISSUE FOR THANKSGIVING DAY IS THAT THE GFS/CANADIAN
PRODUCE QPF OVER THE SOUTHEAST HALF OF THE FORECAST AREA. THIS QPF
IS RELATED TO A SUBTROPICAL SHORTWAVE EJECTING OUT OF AN UPPER LOW
CROSSING NORTHERN MEXICO ON WEDNESDAY. EVERY MODEL SUGGESTS A PLUME
OF HIGHER MOISTURE STREAMING UP INTO THE FORECAST AREA ON
THANKSGIVING...AHEAD OF THE WARM FRONT...NOTED BY 850MB DEWPOINTS
CLIMBING TO 4C OR SO. NEW 19.00Z ECMWF NOW PRODUCES QPF TOO BY
BRINGING THAT SHORTWAVE UP...THOUGH LIGHTER AND OUTSIDE FOR THE
FORECAST AREA. WITH GOOD AGREEMENT ON THE SHORTWAVE COMING UP
THROUGH THE MOISTURE STREAM...KEPT THE CONSENSUS APPROACH ADDITION
OF 20 PERCENT CHANCES FOR THE SOUTHEAST HALF ON THANKSGIVING.
AFTER THE MAIN FRONTAL PASSAGE...ATTENTION TURNS TO WINDS AND
TEMPERATURES AS COLD AIR FILTERS IN. IT APPEARS THE COLDEST AIR
WAITS UNTIL FRIDAY...ASSOCIATED WITH A SECONDARY COLD FRONTAL
PASSAGE. FOR EXAMPLE...850MB TEMPS AT 06Z FRIDAY ARE GENERALLY IN
THE RANGE OF -3C WEST TO 1C EAST. BY 18Z FRIDAY...EVERYONE IS SEEING
850MB TEMPS BETWEEN -10 AND -13C. THUS...TEMPERATURES PROBABLY ARE
NOT GOING TO RISE MUCH ABOVE MORNING LOWS...AND IF ANYTHING POSSIBLY
FALL. GOOD MIXING SETUP TOO GIVING COLD ADVECTION DURING THE DAYTIME
AND UNIDIRECTIONAL LOW LEVEL WINDS. SUSTAINED 15-20 KT WINDS LOOK
REASONABLE WITH GUSTS OF 30-35 KT AT LEAST WEST OF THE MISSISSIPPI
RIVER.
THINGS CALM DOWN FOR FRIDAY NIGHT AND THE WEEKEND AS A RIDGE OF HIGH
PRESSURE CROSSES THE AREA AND BEGINS A WARM UP.
&&
.AVIATION...
1105 PM CST SUN NOV 18 2012
AN UPPER LEVEL SHORTWAVE TROUGH WILL DRIVE NORTHEAST ACROSS THE
REGION TONIGHT. CLOUDS WERE INCREASING AND LOWERING AHEAD OF THE
SHORTWAVE...WHILE 88-D RADAR RETURNS POINTING TO SOME LIGHT SHOWERS
ADVANCING NORTHEAST FROM SOUTHWEST IA. VSBYS WERE GENERALLY P6SM
WITH THE SHOWERS...WITH ONLY T/0.01 AMOUNTS. HRRR DOING A GOOD JOB
CAPTURING THE PCPN...AND WILL REFINE TIMING AT KLSE USING IT.
ALSO...WILL ADD VCSH FOR A SHORT PERIOD AT KRST BASED ON RADAR
TRENDS AND THE HRRR. MEANWHILE...MODELS CONTINUE TO SUGGEST THE
POTENTIAL FOR A FURTHER LOWERING OF CLOUD BASES MONDAY AFTERNOON AS
MOISTURE CONTINUES TO RIDE NORTHWARD AHEAD OF THE SHORTWAVE/S SFC
COLD FRONT. MVFR CAN/T BE RULED OUT FOR A FEW HOURS...BUT CONFIDENCE
NOT HIGH ENOUGH TO INCLUDE IN THE FORECAST AT THIS TIME. THE FRONT
WILL MOVE IN MONDAY NIGHT...LIKELY PASSING KRST NEAR 04Z TUE
AND AFTER 06Z AT KLSE.
&&
.CLIMATE...
200 AM CST SUN NOV 18 2012
RECORD HIGH TEMPERATURES FOR WEDNESDAY/21ST AND THURSDAY/22ND. COOP
SITES ARE 6AM-6AM HIGHS...THUS 22ND HIGHS ARE 21.12Z TO 22.12Z. LA
CROSSE AND ROCHESTER ARE ONLY NON-COOP SITES.
FORECAST HIGH TEMPERATURES SUGGEST SOME OF THE RECORDS BELOW MAY
BE TIED OR BROKEN.
LOCATION WEDNESDAY/21ST THURSDAY/22ND
LA CROSSE WI 72/1990 59/1963
SPARTA WI 65/1990 70/1990
MEDFORD WI 59/1913 65/1990
LANCASTER WI 66/2003 66/1898
MAUSTON WI 67/2003 66/1990
ROCHESTER MN 69/1990 65/1913
AUSTIN MN 70/1990 58/1966
WINONA DAM 5A MN 60/2003 60/2001
WABASHA MN 61/1908 59/1908
CHARLES CITY IA 71/1990 62/1966
OELWEIN IA 71/1990 62/1966
DECORAH IA 71/1990 62/1908
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
200 AM CST MON NOV 19 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
CLIMATE......JONES/DB/AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1105 PM CST SUN NOV 18 2012
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
332 PM CST SUN NOV 18 2012
THE MAIN WEATHER CHALLENGES FOR THIS FORECAST WERE A LIGHT
SCATTERED RAIN SHOWER DAY FOR MONDAY FOLLOWED BY POSSIBLY NEAR
RECORD WARMTH ON WEDNESDAY.
GOES WATER VAPOR IMAGERY SHOWING A WEAK DARKENING SIGNAL
ASSOCIATED WITH A SHORTWAVE TROUGH OVER NRN MN SHIFTING SLOWLY
NORTHEAST. IN COMBINATION WITH WEAK ISENTROPIC LIFT THIS HAS
PROVIDED SOME 7KFT CLOUD COVER OVER WRN WI. THIS ALL AHEAD OF
SHORTWAVE RIDGING IN AN INCREASING MID-HIGHER LEVEL MOIST
SOUTHWEST FLOW WITH ROOTS TO THE TROPICS. NEXT SHORTWAVE TROUGH
HEADING TOWARD THE AREA IS CLEAR IN THE GOES WATER VAPOR TOO IN
NERN NM...WITH A TROPOPAUSE FOLD DOWN TO ABOUT 350 MB...NOT TOO
IMPRESSIVE. 18.12Z RAOB SOUNDINGS SHOWING A VERY DRY AIR MASS
BELOW 15KFT TO THE SOUTHWEST...WITH SOME SMALL INCREASES UPSTREAM
IN TOPEKA KS AND NORMAN OK. STILL...NOT A VERY MOIST AIR MASS IN
THE RETURN FLOW FROM THE GULF IN THE LOWEST LEVELS.
SHORTWAVE TROUGH OVER NERN MN WILL CONTINUE NORTHEAST..AND
ARRIVES IN THE AREA LATE TONIGHT. THICK CLOUDS MOVING IN AND
SOUTHERLY WINDS WILL KEEP OVERNIGHT LOWS ABOVE NORMAL HIGH
TEMPERATURES FOR THIS TIME OF YEAR. 18.06Z AND 18.12Z HI-RES WRF
RUNS ARE SUGGESTING THE MID-LEVEL CLOUDS WILL HANG AROUND IN THE
EVENING BEFORE SHIFTING NORTHEAST BUT OVERALL AN INCREASE IN CLOUD
IS FORECAST OVERNIGHT. SOUTHERLY FLOW CONTINUES WITH WEAK
ISENTROPIC LIFT AND ONLY 1 TO 2 UB/S UPWARD VERTICAL MOTION ALOFT
FROM 500-300MB QG DIAGNOSTICS WITH CONSENSUS 18.12Z GUIDANCE RUNS.
HI-RES WRF MODELS SUGGESTING SOME REFLECTIVITY TO BE AROUND BY
12Z MONDAY MOVING IN FROM THE SOUTH BUT STRUGGLES CONTINUE WITH
DRY LOWER LEVELS AND PRECIPITATION MAKING IT TO THE GROUND. STILL
THINK SOME VERY LIGHT SHOWERS OR SPRINKLES WILL BE AROUND FOR
MONDAY WITH CLOUDS AND MILD TEMPERATURES. FORECAST CHANGES WERE
MINOR FOR THIS WEATHER PERIOD BUT DID SLOW THE TIMING OF ONSET AND
MOVED THE WEATHER EAST MONDAY LATER AFTERNOON.
SHORTWAVE TO SHIFT EAST OVERNIGHT MONDAY NIGHT IN COMBINATION WITH
NORTHERN STREAM TROUGH...AND SUBSIDENCE KICKS IN TUESDAY THROUGH
WEDNESDAY FOR CLEAR WEATHER.
RIDGE BUILDING AND WARMING KICKS IN TUESDAY NIGHT AND WEDNESDAY
WITH A WARM FRONT AND WARM TONGUE MOVING IN OFF THE HIGH PLAINS
WEDNESDAY. THE 18.12Z NAM....ECMWF AND 18.09Z SREF MEAN 850MB
TEMPERATURES SHOWING VERY NEAR 2 STANDARD DEVIATIONS ABOVE NORMAL
OVER THE AREA FOR WEDNESDAY. THIS WOULD SUGGEST WE ARE GETTING
NEAR RECORD WARMTH. MODEL GUIDANCE CONSENSUS IS ALSO VERY DRY
THROUGH THE COLUMN SUGGESTING FULL SUN IS LIKELY. WITH THE LOW-
LEVEL PRESSURE GRADIENT IN PLACE...VERTICAL MIXING WILL BE
ENHANCED AS WELL. THE CONSENSUS 925MB TEMPERATURES ARE ABOUT 12C
BY LATE AFTERNOON...SLIGHTLY WARMER IN THE WEST. WITH TODAYS HIGHS
55-60F TODAY UNDER 7-8C AT 925MB...BELIEVE UPPER 60S TO 70F IS NOT
OUT OF THE QUESTION WITH 12C AT 925MB WEDNESDAY. HAVE AGAIN INCREASED
HIGHS TO ABOVE ALL MODEL GUIDANCE VALUES AND CLOSER TO RECORDS.
HOWEVER...RECORD HIGHS ARE QUITE WARM WEDNESDAY FROM A 1990 PRE-
FRONTAL DAY THAT WAS VERY SIMILAR TO THIS YEAR /SEE CLIMATE SECTION
BELOW/. HAVE MID-60S NOW IN THE FORECAST...COOLER IN CENTRAL WI.
MOS HIGHS HAVE BEEN IGNORED FOR WEDNESDAY.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
332 PM CST SUN NOV 18 2012
THIS PERIOD WILL BE DRY IT APPEARS AND CHARACTERIZED BY A RETURN
TO NORMAL TEMPERATURES AS A COLD FRONT MOVES THROUGH LATER
THURSDAY. THIS TIMING IS IN PRETTY GOOD AGREEMENT AMONG THE LATEST
MODEL GUIDANCE. THE 18.12Z ECMWF IS NOW STRONGER WITH THIS SHORTWAVE
TROUGH AND HAS A POOL OF -15C AT 850MB MOVING SWIFTLY ACROSS THE
AREA FRIDAY. IF THIS SOLUTION VERIFIES...A COLDER AND WINDIER
BLACK FRIDAY IS IN STORE THAN IS CURRENTLY FORECAST. COLD WOULD
LAST INTO SATURDAY BEFORE LARGER SCALE RIDGING AND WARMING ENSUES
INTO NEXT WEEK. SIGNALS IN THE LONGER RANGE SUGGESTING A LONGER
WAVE TROUGH MOVING INTO THE WEST AND AN ABOVE NORMAL WARM PERIOD
INTO EARLY NEXT WEEK ACROSS THE CENTRAL U.S. /HIGHS IN THE 50S/.
&&
.AVIATION...
1105 PM CST SUN NOV 18 2012
AN UPPER LEVEL SHORTWAVE TROUGH WILL DRIVE NORTHEAST ACROSS THE
REGION TONIGHT. CLOUDS WERE INCREASING AND LOWERING AHEAD OF THE
SHORTWAVE...WHILE 88-D RADAR RETURNS POINTING TO SOME LIGHT SHOWERS
ADVANCING NORTHEAST FROM SOUTHWEST IA. VSBYS WERE GENERALLY P6SM
WITH THE SHOWERS...WITH ONLY T/0.01 AMOUNTS. HRRR DOING A GOOD JOB
CAPTURING THE PCPN...AND WILL REFINE TIMING AT KLSE USING IT.
ALSO...WILL ADD VCSH FOR A SHORT PERIOD AT KRST BASED ON RADAR
TRENDS AND THE HRRR. MEANWHILE...MODELS CONTINUE TO SUGGEST THE
POTENTIAL FOR A FURTHER LOWERING OF CLOUD BASES MONDAY AFTERNOON AS
MOISTURE CONTINUES TO RIDE NORTHWARD AHEAD OF THE SHORTWAVE/S SFC
COLD FRONT. MVFR CAN/T BE RULED OUT FOR A FEW HOURS...BUT CONFIDENCE
NOT HIGH ENOUGH TO INCLUDE IN THE FORECAST AT THIS TIME. THE FRONT
WILL MOVE IN MONDAY NIGHT...LIKELY PASSING KRST NEAR 04Z TUE
AND AFTER 06Z AT KLSE.
&&
.CLIMATE...
332 PM CST SUN NOV 18 2012
RECORD HIGH TEMPERATURES FOR WEDNESDAY/21ST AND THURSDAY/22ND. COOP
SITES ARE 6AM-6AM HIGHS...THUS 22ND HIGHS ARE 21.12Z TO 22.12Z. LA
CROSSE AND ROCHESTER ARE ONLY NON-COOP SITES.
LOCATION WEDNESDAY/21ST THURSDAY/22ND
LA CROSSE WI 72/1990 59/1963
SPARTA WI 65/1990 70/1990
MEDFORD WI 59/1913 65/1990
LANCASTER WI 66/2003 66/1898
MAUSTON WI 67/2003 66/1990
ROCHESTER MN 69/1990 65/1913
AUSTIN MN 70/1990 58/1966
WINONA DAM 5A MN 60/2003 60/2001
WABASHA MN 61/1908 59/1908
CHARLES CITY IA 71/1990 62/1966
OELWEIN IA 71/1990 62/1966
DECORAH IA 71/1990 62/1908
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
332 PM CST SUN NOV 18 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM....BAUMGARDT
AVIATION.....RIECK
CLIMATE......JONES/DB
AREA FORECAST DISCUSSION
NWS NEW YORK NY
347 AM EST WED NOV 21 2012
.SYNOPSIS...
HIGH PRESSURE ALONG THE EASTERN SEABOARD WILL REMAIN IN CONTROL OF
OUR WEATHER INTO FRIDAY. A COLD FRONT WILL MOVE ACROSS THE AREA
LATE FRIDAY NIGHT FOLLOWED BY HIGH PRESSURE BUILDING IN FROM THE
WEST THIS WEEKEND INTO EARLY NEXT WEEK. A COMPLEX STORM SYSTEM
APPROACHES THE AREA ON TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CIRRUS FROM UPPER SHORTWAVE IS PROGRESSING EAST. HAVE FOLLOWED
LATEST RAP TIME-LAGGED ENSEMBLE FOR CLOUD GRIDS WHICH IS VERY
CLOSE TO OBSERVED TREND. THIS RESULTS IN A SUNNY OR BECOMING SUNNY
NORTH AND EAST FCST.
TEMPS TODAY ARE CLOSE TO GFS MOS. WHILE MAVS HAVE BEEN TOO WARM OF
LATE AND BIAS CORRECTED GRIDDED GFS MOS IS 3 DEGREES
COOLER...BELIEVE NEARLY FULL SUN WILL ALLOW THE 50 TO 55 FCST TO
VERIFY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
HIGH PRESSURE PERSISTS. THUS...CONTINUED WITH A PERSISTENCE FCST.
STRATUS DECK FROM GULF OF MAINE CLIPS SE CT AND LONG ISLAND
OVERNIGHT AS SEEN IN GFS LOW LEVEL RH FIELDS.
THANKSGIVING FINDS LIGHT NE WINDS AND MOSTLY SUNNY SKIES - A FINE
DAY FOR A PARADE...TRAVEL AND GIVING THANKS.
TEMPS ARE FCST JUST A TAD ABOVE NORMAL AND CLOSE TO GFS MOS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE NAM IS A FAST OUTLIER WITH THE COLD FRONT FRIDAY AND FRIDAY
NIGHT...SO DISCARDED ITS GENERAL SOLUTION. USED A GFS/ECMWF/CMC-
GLOBAL BLEND THURSDAY NIGHT-MONDAY. THE GFS QUITE LIKELY...GIVEN
ITS KNOWN BIAS TO ERODE HIGHS OVER THE CANADIAN MARITIMES/NORTH
ATLANTIC TO QUICKLY...A BIT FAR N/W AND TOO FAST WITH THE SYSTEM
APPROACHING BY TUESDAY...SO LEANED TOWARDS TO THE ECMWF THERE
AFTER...NOTING SUPPORT FROM THE CMC-GLOBAL THROUGH 144 HOURS.
A DEEP LAYERED RIDGE CROSSES THE AREA THURSDAY NIGHT...GIVING WAY
TO AN APPROACHING FULL LATITUDE TROUGH FRIDAY AND FRIDAY NIGHT. THIS
TROUGH THEN CROSSES THE AREA SATURDAY AND SATURDAY NIGHT.
IN TERMS OF SENSIBLE WEATHER...THURSDAY NIGHT SHOULD BE DRY DUE TO
SUBSIDENCE UNDER THE RIDGE. HAVE SLIGHT CHANCE POPS IN FAR WESTERN
ZONES FRIDAY (CHANCE FAR W ORANGE) FRIDAY AFTERNOON...THEN CHANCE
POPS FOR ALL BUT FAR SW ZONES FRIDAY NIGHT WITH THE PASSAGE OF THE
SURFACE COLD FRONT. ALL GUIDANCE SUGGESTS THAT PRECIPITATION COULD
HAVE TROUBLE GETTING INTO NYC METRO FRIDAY NIGHT...SO ONLY SLIGHT
CHANCE POPS THERE. SLIGHT CHANCE POPS WEST/CHANCE POPS EVERYWHERE
SATURDAY DUE TO INSTABILITY AND LINGERING POST-FRONTAL SHOWERS.
APPEARS SHOULD HAVE ENOUGH LOW LEVEL COLD AIR WORK IN LATE FRIDAY
NIGHT THAT NW ZONES COULD SEE A -SHRA/-SHSN MIX AND POSSIBLE
CHANGE TO ALL SNOW SHOWERS SATURDAY MORNING. EXPECT SUFFICIENT
BOUNDARY LAYER WARMING THAT SHOULD SEE ONLY -SHRA IN THE
AFTERNOON. EXPECT GUSTY NW WINDS IN RESPONSE TO STRONG LOW LEVEL
COLD ADVECTION SATURDAY. SHOULD SEE SUFFICIENT DRYING BY SATURDAY
NIGHT WITH CONTINUING GUSTY NW WINDS TO GO WITH A DRY FORECAST
THEN.
NW FLOW ALOFT SUNDAY AND SUNDAY NIGHT GIVES WAY TO RIDGING
BUILDING IN MONDAY...WITH DRY CONDITIONS ACROSS THE REGION.
THE RIDGE SLIDES TO THE EAST MONDAY NIGHT. SW FLOW ALOFT ON
TUESDAY AHEAD OF A FULL LATITUDE TROUGH BUILDING INTO THE GREAT
LAKES AND MID- SOUTH. A SURFACE LOW SHOULD TRACK TO THE EASTERN
GREAT LAKES BY TUESDAY NIGHT. WITH ITS ASSOCIATED WARM FRONT
LIKELY STAYING TO OUR S MONDAY NIGHT AND TUESDAY...WENT WITH
STRATIFORM PRECIPITATION IN RESPONSE TO OVER RUNNING WITH SLIGHT
CHANCE POPS MONDAY NIGHT AND CHANCE POPS TUESDAY. FOR NOW HAVE A
WINTRY MIX CHANGING TO RAIN ACROSS NORTHERN INTERIOR ZONES...AND
JUST RAIN OVER SOUTHERN ZONES MONDAY NIGHT AND TUESDAY.
FOR TEMPERATURES THURSDAY NIGHT AND FRIDAY...USED A BLEND OF MAV/MET
GUIDANCE...MIXING IN NAM 2-METER TEMPERATURES AND MIXING DOWN FROM
950 HPA FOR HIGHS TUESDAY...WITH TEMPERATURES SLIGHTLY ABOVE
NORMAL IN BOTH PERIODS.
FROM FRIDAY NIGHT THROUGH TUESDAY USED A BLEND OF MEX/MEX ENSEMBLE
MEAN/HPC GUIDANCE...WEIGHING MORE AND MORE TOWARDS ECE GUIDANCE
TOWARDS THE END OF THE PERIOD. EXCEPT FOR NEAR NORMAL LOWS FRIDAY
NIGHT...EXPECT BELOW NORMAL TEMPERATURES IN THIS TIME FRAME.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
HIGH PRES WILL BUILD SWD OVER THE REGION THRU THANKSGIVING.
LGT NE WINDS THRU THE TAF PERIOD. SPEEDS AROUND 10KT DURING THE
DAYTIME HRS.
MAINLY VFR TODAY WITH MID AND HIGH CLOUDS. LOW POTENTIAL FOR CIGS
AROUND 3K FT TO DEVELOP KISP-KGON AFT 16-18Z. MVFR STRATUS LIKELY TO
DEVELOP TNGT. THIS SHOULD OVERSPREAD THE AREA FROM THE E. MVFR HAS
BEEN INCLUDED IN THE TAFS. POTENTIAL EXISTS FOR THIS STRATUS TO
REMAIN OFFSHORE...BUT THE PROB IS HIGHER THAT IT WILL IMPACT THE
AREA TERMINALS ATTM.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP://WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KJFK FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KLGA FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
.OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY...
.THURSDAY...MVFR IN THE MRNG. VFR IN THE AFTN. NE FLOW AROUND 10KT.
.THURSDAY NIGHT-FRIDAY...VFR.
.FRIDAY NIGHT...COLD FROPA...ACCOMPANIED BY SCT SHOWERS WITH
POSSIBLE BRIEF MVFR CONDS. NW WINDS G25-30KT BEHIND FROPA.
.SATURDAY...SOME SNOW FLURRIES POSSIBLE NW OF CITY TERMINALS. NW
WINDS G25-30KT.
.SUNDAY...GUSTY NW WINDS G15-20KT.
&&
.MARINE...
PERSISTENT NE FLOW CONTINUES THROUGH EARLY FRIDAY BETWEEN INLAND
HIGH PRESSURE AND A DISTANT OCEAN LOW. WINDS REMAIN BELOW SCA
LEVELS...BUT OCEAN SEAS WILL REMAIN IN THE 5-7 FT RANGE VIA SE
SWELL FROM THE OFFSHORE LOW.
THE HIGH SHOULD EVENTUALLY GIVE WAY TO A COLD FRONT FRIDAY NIGHT.
WINDS WILL INCREASE BEHIND THIS FRONT...AND SHOULD BE AT THEIR
STRONGEST SAT AFTERNOON AND SAT NIGHT. IN FACT...GUSTS COULD
APPROACH GALE FORCE DURING THIS TIME AS MUCH COLDER AIR RUSHES IN.
WINDS ABATE SOMEWHAT SUNDAY...BUT WILL REMAIN GUSTY AS HIGH PRESSURE
BUILDS WELL TO THE SOUTH.
SEAS WILL REMAIN RATHER ROUGH ON THE OCEAN WATERS THURSDAY INTO
FRIDAY DUE TO EASTERLY SWELL.
LINGERING SE SWELLS SHOULD KEEP SEAS AT SCA LEVEL FRIDAY
NIGHT...WITH SUB-SCA CONDITIONS ELSEWHERE. GALE FORCE GUSTS LIKELY
ON ALL WATERS SATURDAY...DUE TO STRONG LOW LEVEL COLD ADVECTION.
THESE GUSTS COULD LINGER INTO EARLY SUNDAY. AT LEAST SCA
CONDITIONS EXPECTED ON SUNDAY.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION EXPECTED THROUGH MONDAY.
&&
.EQUIPMENT...
THE KOKX WSR-88D IS OUT OF SERVICE DUE TO A MAJOR NON STORM
RELATED MECHANICAL FAILURE. THE RADAR IS EXPECTED TO RETURN TO
SERVICE BY THE FIRST WEEK OF DECEMBER.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 AM EST FRIDAY
FOR ANZ350-353-355.
&&
$$
SYNOPSIS...TONGUE/MALOIT
NEAR TERM...TONGUE
SHORT TERM...TONGUE
LONG TERM...MALOIT
AVIATION...12
MARINE...TONGUE/MALOIT
HYDROLOGY...TONGUE/MALOIT
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
353 AM CST WED NOV 21 2012
.DISCUSSION...
922 PM CST
HAVE EXPANDED THE DENSE FOG ADVISORY TO INCLUDE THE REMAINDER OF
THE FORECAST AREA...INCLUDING ALL OF CHICAGO...AS OBSERVATIONAL
GUIDANCE CONTINUES TO FALL IN LINE WITH THE IDEAL SYNOPTIC AND
MESOSCALE PATTERNS FOR DENSE FOG.
NOT MUCH TO ADD FROM PREVIOUS REASONING IN DISCUSSIONS BELOW. THE
00Z DVN SOUNDING REVEALED A CLASSIC FOG SOUNDING GOING INTO THE
EVENING. THE AREA OF PERSISTENT DENSE FOG CENTERED ON THE
MISSISSIPPI RIVER CONTINUES TO EXPAND EASTWARD...LINING UP WITH
THE SURFACE RIDGE AXIS PERFECTLY. OFF OF LAKE MICHIGAN INTO
NORTHWEST IN/SOUTHWEST MI...DENSE FOG HAS DEVELOPED/EXPANDED
INLAND DUE LIKELY TO SLIGHTLY HIGHER MOISTURE...ALTHOUGH IT SEEMS
PATCHY TO AREAS AT TIMES BASED ON WEBCAMS AND REPORTS. AS FOR
IN-BETWEEN THESE TWO PRONOUNCED AREAS...THE ATMOSPHERE SHOULD
CONTINUE TO SATURATE AND FORECAST SOUNDINGS INDICATE DENSE FOG
FOR MUCH OF THE OVERNIGHT AND INTO WEDNESDAY MORNING. SOME CONCERN
THIS FOG COULD LAST ALL THE WAY TO NOON. NO MATTER WHAT...THIS
WILL HAVE IMPACTS ON ANY EARLY TO MID MORNING HOLIDAY TRAVELERS.
IN ADDITION...HAVE FURTHER STIFLED THE TYPICAL DIURNAL TEMPERATURE
INCREASE WEDNESDAY MORNING...AND LOWERED HIGH TEMPERATURES BY 2-3
DEGREES. THESE MAY END UP NEEDING TO BE LOWERED MORE...AS THE LATE
NOVEMBER LOW SUN ANGLE WILL HAVE SOME DIFFICULTY ERODING THIS FOG.
MTF
//PREV DISCUSSION...
628 PM CST
HAVE SPED UP THE START TIME OF THE DENSE FOG IN THE FORECAST...AND
WITH FURTHER INCREASED CONFIDENCE ON THE AREA TO MOST LIKELY BE
IMPACTED...HAVE GONE AHEAD AND ISSUED A DENSE FOG ADVISORY FOR
NORTH CENTRAL ILLINOIS AND FAR WESTERN AND NORTHERN AREAS OF THE
CHICAGO METROPOLITAN AREA. THIS MAY VERY WELL NEED TO BE EXPANDED
IN TWO TO THREE HOURS.
WINDS HAVE BECOME CALM OR LIGHT AND VARIABLE ACROSS THE ENTIRE
AREA EARLY THIS EVENING AS THE RIDGE AXIS HAS EXPANDED INTO
NORTHERN IL. DEW POINTS REMAIN ANOMALOUSLY HIGH WITH MID 40S...AND
TEMPERATURE DROPS AT A HANDFUL OF SITES HAVE BEEN AROUND OR EVEN
HIGHER THAN 10F SINCE 4 PM. THIS HAS RESULTED IN T/TD SPREADS OF
LESS THAN 5F ALREADY ACROSS NORTH CENTRAL IL. IN ADDITION..THE
AREAS OF FOG THAT PERSISTED THROUGH TODAY IN EASTERN IA/FAR
SOUTHWEST WI THAT WERE MENTIONED IN THE PRIOR DISCUSSION HAVE ONLY
BLOSSOMED SINCE SUNDOWN. VISIBILITY OBSERVATIONS IN THESE AREAS
ARE ALMOST ALL AT ONE QUARTER MILE OR LESS. SO WITH THE RIDGE AXIS
ONLY FURTHER TRANSITIONING OVER THE AREA THROUGH LATE
EVENING...WOULD EXPECT VISIBILITY TO DROP AND ESPECIALLY RAPID IN
THOSE AREAS WHERE THE PERSISTING FOG EXPANDS IN /WESTERN WINNEBAGO
AND OGLE COUNTIES BY 830 PM/. THE HRRR FORECAST VISIBILITY AGREES
WITH THIS IDEA OF EASTWARD EXPANSION THROUGH LATE EVENING AND
OVERNIGHT.
AS FOR AREAS TO THE EAST...INCLUDING MUCH OF
CHICAGOLAND...WIDESPREAD 3-6 SM VISIBILITIES EXIST. THESE
VISIBILITIES AND WEBCAMS HAVE INDICATED VERY GRADUAL VISIBILITY
REDUCTION SINCE SUNDOWN. LINGERING CLOUDS AND ASSOCIATED MOIST
LAYER AROUND 3K FT ARE LIKELY IMPAIRING FULL RADIATIONAL COOLING
SOMEWHAT...BUT DO FULLY EXPECT THESE AREAS TO COOL MORE QUICKLY
AND DENSE FOG AT LEAST IN PLACES TO DEVELOP. AREAS NEAR THE LAKE
MAY ACTUALLY BECOME MORE FAVORED TO SEE THE FOG MORE QUICKLY DUE
TO A LIGHT BUT MOIST ONSHORE COMPONENT.
IMPROVEMENT IN THE FOG ON WEDNESDAY MORNING MAY BE EXTREMELY
SLOW...WITH SOME AREAS OF FOG LASTING INTO THE EARLY AFTERNOON
GIVEN WHAT OCCURRED UPSTREAM IN EASTERN IOWA TODAY AND JUST THE
CLIMATOLOGY OF THIS TIME OF YEAR. WILL FURTHER ASSESS THIS WITH
00Z GUIDANCE.
MTF
//PREV DISCUSSION...
256 PM CST
TONIGHT THROUGH WEDNESDAY...
GREATEST CONCERN FOR TONIGHT RESIDES WITH THE EXPECTED DEVELOPMENT
OF FOG...TRANSITIONING INTO AREAS OF DENSE FOG OVERNIGHT. THE
OTHER CONCERN IS THAT ONE OF THE BUSIEST TRAVEL DAYS OF THE YEAR
WILL HAVE A SLOW START GIVEN THE EXPECTED DEVELOPMENT OF FOG.
LOOKING UPSTREAM ACROSS EASTERN IOWA FOG HAS LINGERED INTO THIS
AFTERNOON...WITH A FEW LOCATIONS STILL SEEING VSBYS DOWN AROUND 1 TO
2 MILES. THIS AFTN HAS SEEN ALMOST NO MIXING WITH LGT WINDS
GENERALLY LESS THAN 5 MPH...AND DEW POINTS HOLDING UP IN THE MID 40S
FOR MANY LOCATIONS OF NORTHERN IL/NORTHWEST IN. HIGH PRESSURE WILL
REMAIN OVERHEAD TONIGHT...WHICH WILL AID IN DECENT RADIATIONAL
COOLING SHORTLY AFTER SUNSET. THIS ALL POINTS TOWARDS A REPEAT NIGHT
OF AREAS OF FOG AND POTENTIALLY AREAS OF DENSE FOG. OVERNIGHT LOWS
WILL COOL INTO THE LOW 40S...WITH THE EXCEPTION OF AREAS ADJACENT TO
LAKE MICHIGAN WHERE TEMPS MAY HOLD IN THE MID 40S.
ONCE THE FOG DOES DEVELOP IT WILL MOST LIKELY LINGER INTO WED
MORNING...POSSIBLY THROUGH MIDDAY. GIVEN THE SCENARIO OF WHAT HAS
TRANSPIRED ACROSS EASTERN IOWA...COULD SEE THE DENSE FOG LIFT BY
MID-MORNING THEN PATCHY FOG THROUGH NOON. THIS WILL RESULT IN
TEMPERATURES BEING SLOW TO WARM...THUS HAVE SLOWED THE RATE OF CLIMB
UNTIL MIDDAY. THROUGHOUT THE MORNING HOURS TEMPS WILL REMAIN IN THE
LOW/MID 40S...THEN BY MIDDAY AND IMPROVING VSBYS OR BURNING OFF
FOG...TEMPS WILL BEGIN TO CLIMB RAPIDLY INTO THE UPR 50S AND
POSSIBLY 60 DEG IN A FEW LOCATIONS. OTHERWISE SKIES WILL BECOME
MOSTLY CLEAR IN THE AFTERNOON HOURS.
CONFIDENCE...HIGH.
CONFIDENCE ON AREAS OF DENSE FOG...MEDIUM/HIGH.
THANKSGIVING...
500MB RIDGE REMAINS OVERHEAD...WITH A POTENT THERMAL RIDGE AT 850MB
OF 10 TO 12 DEG C. A FEW ENSEMBLE MEMBERS SUGGEST THAT 850MB TEMPS
COULD BE SLIGHTLY WARMER TO 14 DEG C. THE BETTER PRESSURE GRADIENT
REMAINS DISPLACED TO THE NORTHWEST OF THE REGION...WHICH IS THE AREA
THAT WILL SEE THE STRONGEST WARM AIR ADVECTION. EITHER WAY...IT
APPEARS THANKSGIVING WILL END UP BEING A RATHER WARM DAY WITH TEMPS
LIKELY TO REACH THE LOW 60S. PLUMES CONTINUE TO INDICATE A HIGH
CONFIDENCE THAT TEMPS WILL EASILY PUSH TO 60 DEGREES BY NOON. THE
LARGEST CAVEAT COULD BE THAT INCREASED MOISTURE APPEARS TO BE
PROGGED TO POOL ALONG THE BOUNDARY INTO THE MID-MISSISSIPPI
VALLEY...WHICH COULD PUSH CLOUDS OVERHEAD BY LATE MORNING. THIS
MAINLY WILL AFFECT THE WESTERN HALF OF THE CWFA. IN ADDITION HAVE
OVERSPREAD A SLIGHT CHC OF PRECIP BY MIDDAY ALONG AND NORTH OF A LA
SALLE TO CRYSTAL LAKE LINE. THEN ADDITIONAL MOISTURE CONTINUES TO
POUR INTO THE CWFA BY MID-AFTERNOON/EVENING...SO HAVE MAINTAINED
MENTION OF SLT CHC OF RA.
CONFIDENCE IN TEMPS...HIGH.
CONFIDENCE IN PRECIP...LOW.
FRIDAY THROUGH MONDAY...
ENSEMBLES THROUGH THE EXTENDED PERIODS CONTINUE TO SHOW MINIMAL
SPREAD IN ENVELOPE OF SOLUTIONS...LEADING TO THE INCREASED
CONFIDENCE THAT A PATTERN CHANGE IS UPON US. FRIDAY WILL KICK OFF
THE EXTENDED WITH A TASTE OF COLDER AIR...HOWEVER WHAT APPEARS TO BE
TAKING SHAPE FOR MID/LATE NEXT WEEK WILL BE MUCH MORE SIGNIFICANT AS
THE CALENDAR APPROACHES THE FIRST OF DECEMBER.
GUIDANCE CONTINUES TO PROG FRONTAL PASSAGE FOR THE FIRST HALF OF
FRI...POSSIBLY PRIOR TO DAYBREAK. VERY TIGHT PRESSURE GRADIENT IS
ALSO POISED TO ARRIVE BEHIND THE FRONTAL PASSAGE FRI...RESULTING IN
BREEZY CONDITIONS. WITH COOLER AIR STEADILY ADVECTING IN FROM THE
NORTHWEST AS A RESULT OF AN 850MB THERMAL TROUGH OF -10 TO -14 DEG
C...MAX TEMPS FRI COULD BE ACHIEVED PRIOR TO MID-MORNING. THEN IT
APPEARS FALLING TEMPS WILL OCCUR EARLY IN THE AFTERNOON. AT THIS
TIME IT APPEARS A DRY WEDGE WILL OCCUR FRI...SHIFTING ANY MOISTURE
EAST OF THE CWFA. THEN THE TRANSITION TOWARDS LAKE EFFECT PRECIP
DEVELOPS FRI AFTERNOON THROUGH SATURDAY EVENING...WHICH FORTUNATELY
WITH A STRONG WEST/NORTHWEST FLOW THIS PRECIP WILL BE DISPLACED
DOWNSTREAM ACROSS LOWER MICHIGAN AND PERHAPS PORTIONS OF NORTHWEST
INDIANA.
SAT/SUN WILL SEE ANTI-CYCLONIC FLOW PUSH BACK OVERHEAD WITH DRY
WEATHER EXPECTED THROUGH THE WEEKEND INTO EARLY MON. 500MB TROUGH
PIVOTS EAST WITH A RELATIVELY FLAT OR SEMI-ZONAL FLOW SUN/MON. SAT
HIGH TEMPS WILL STRUGGLE TO WARM INTO THE MID/UPR 30S. SUN/MON WILL
BEGIN TO WARM MARGINALLY INTO THE LOW 40S. THIS ALL APPEARS TO BE
TEMPORARY AS THE DEVELOPMENT OF A BLOCKING PATTERN BEGINS TO TAKE
SHAPE OVER ALASKA AND THE NORTH ATLANTIC...WHICH WILL ULTIMATELY
ALLOW MUCH COLDER AIR TO ARRIVE INTO CENTRAL CANADA MID/LATE NEXT
WEEK FROM SIBERIA.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* DENSE FOG THROUGH THE MORNING...IMPROVING TO MVFR VSBY BY NOON.
* REDUCED VERTICAL VISIBILITIES OF 100 FT THROUGH MID MORNING
BECOMING 100 FT CIGS THROUGH NOON.
JEE
//DISCUSSION...UPDATED 09Z...
DENSE FOG HAS FINALLY ARRIVED AT ORD AND MDW LEADING TO SLIGHTLY
GREATER CONFIDENCE ABOUT THIS MORNINGS FORECAST. FOG HAS BECOME
THICKER VERTICALLY WHICH SHOULD MAKE IT HARDER TO MIX OUT IN THE
MORNING. WINDS STILL LOOK LIKE THEY WILL BE SLOW TO COME UP AND
THERE IS THE POSSIBILITY THAT AS THEY COME UP DENSE FOG COULD BE
ADVECTED INTO THE EASTERN TERMINALS THROUGH MID MORNING OR PERHAPS
LATER. GOING TO STAY WITH 06Z TAF TIMING AS FAR AS HOW QUICKLY
VSBY AND CIGS IMPROVE. ONE EXCEPTION IS AT RFD WHERE TIMING WAS
PUSHED AN HOUR BACK DUE TO THE THICKNESS OF THE FOG AND HOW LARGE
OF AN AREA IS COVERED BY DENSE FOG IN CENTRAL IL.
PREVIOUS DISCUSSION...06Z...
BROAD HIGH PRESSURE HAS SETTLED OVER THE REGION WITH WEAK TO CALM
WINDS. CLEAR SKIES HAVE ALLOWED FOR EFFICIENT RADIATIONAL COOLING
AND DENSE FOG DEVELOPMENT. MONITORING TWO AREAS OF DENSE FOG. THE
FIRST IS WEST OF A JVL TO RFD TO PIA LINE. THE SECOND IS EAST OF A
GYY TO IKK LINE. AT ITS CURRENT SPEED...THE WESTERN REGION OF
DENSE FOG WILL MOVE OVER ORD AND MDW BY 17Z. STATIONS UPSTREAM
HAVE SUDDENLY DROPPED FROM 2 SM TO 1/4 SM OR LESS AS THE AREA OF
DENSE FOG MOVES OVERHEAD. THINKING ORD AND MDW WILL NOT DROP TO
LESS THAN 1/4 SM. AS VSBY SETTLES IN ALSO EXPECTING VERTICAL
VISIBILITIES TO BE REDUCED TO 100 FT OR LESS.
SOUTHWEST FLOW WILL SLOWLY INCREASE TOMORROW MORNING...SLOWER THAN
PREVIOUSLY INDICATED. AS SUCH MOVED TIME OF MVFR VSBY IMPROVEMENT
BACK TO NOON. THE FOG WILL NOT DISSIPATE OR IMPROVE UNTIL BOUNDARY
LAYER MIXING GETS GOING. AS FOG MIXES OUT...EXPECTING IT TO RISE
RESULTING IN A PERIOD OF BKN001 CIGS MID WEDNESDAY MORNING THROUGH
ABOUT NOON. EXPECTING TO RETURN TO VFR BY MID WEDNESDAY AFTERNOON.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* HIGH CONFIDENCE IN CIG VALUES.
* MEDIUM-HIGH CONFIDENCE IN VSBY...1/4SM LIKELY...M1/4SM PSBL.
* MEDIUM-HIGH CONFIDENCE OF TIMING OF VSBY/CIG IMPROVEMENT.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...GUSTY SOUTHERLY WINDS AND CHANCE OF SHRA...OTHERWISE
VFR.
FRIDAY...MVFR POSSIBLY EARLY...GUSTY NW WINDS...OTHERWISE VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...SLIGHT CHANCE SHRA...OTHERWISE VFR.
RODRIGUEZ
&&
.MARINE...
343 AM CST
HIGH PRESSURE IS STRETCHED ACROSS THE MIDWEST THIS MORNING WITH
LIGHT SOUTHWEST WINDS ACROSS THE LAKE. THE HIGH WILL DRIFT EAST
TODAY WHILE THE NEXT LOW PRESSURE SYSTEM MOVES INTO THE NORTHERN
PLAINS. AS SUCH THE PRESSURE GRADIENT OVERHEAD WILL TIGHTEN WITH
WINDS BECOMING SOUTH AND INCREASING TO 30 KT. THE LOW PASSES TO THE
NORTH TOMORROW AND ITS COLD FRONT SLIDES THROUGH THURSDAY NIGHT.
FOR THE NEARSHORE WATERS...GOING WITH A SMALL CRAFT ADVISORY
BEGINNING THURSDAY MORNING FOR WINDS 20 TO 30 KT. GUIDANCE
INDICATES WINDS WILL DIMINISH TO BELOW 25 KT THURSDAY NIGHT AS THE
COLD FRONT MOVES THROUGH. WAVES WILL ALSO DIMINISH WITH THE FRONTAL
PASSAGE AND WESTERLY WIND SHIFT SO ENDED THE SMALL CRAFT THURSDAY
EVENING. HOWEVER EXPECTING WINDS TO INCREASE BACK TO AT LEAST 20
TO 30 KT AGAIN FRIDAY MORNING. SOME GUIDANCE MEMBERS INDICATE
GALES TO 35 KT MAY BE POSSIBLE...BUT THINKING TO 30 KT IS THE
BETTER BET RIGHT NOW. AS SUCH EXPECTING ANOTHER SMALL CRAFT
ADVISORY FOR FRIDAY MORNING THROUGH SATURDAY AFTERNOON/EVENING
DEPENDING HOW LONG IT TAKES THE WAVES TO SUBSIDE.
FOR THE OPEN WATERS...OCCASIONAL GALES ARE POSSIBLE OVER THE
NORTHERN HALF OF THE LAKE THURSDAY AS STRONG WARM AIR ADVECTION WILL
BE IN FULL SWING. THINKING THE AIR DIRECTLY ABOVE THE LAKE WILL BE
STABLE ENOUGH THAT A GALE HEADLINE WILL NOT BE NEEDED...HOWEVER A
FEW GALE GUSTS MAY REACH THE SURFACE. THE BETTER BET FOR GALES IS
BEHIND THE COLD FRONT BEGINNING THURSDAY NIGHT. GALES WILL BE
STRONGEST OVER THE NORTHERN HALF OF THE LAKE CLOSER TO THE LOW.
EXPECTING GALES TO DIMINISH QUICKLY FRIDAY NIGHT AS HIGH PRESSURE
APPROACHES FROM THE WEST. WINDS WILL BECOME WEAK WITH HIGH PRESSURE
OVER THE REGION SATURDAY NIGHT. ANOTHER LOW PRESSURE SYSTEM WITH
SOUTHWEST WINDS IS EXPECTED TO PASS NORTH OF THE AREA ON
SUNDAY...BUT GUIDANCE DIFFERS ON HOW STRONG THE LOW WILL DEEPEN AND
ITS PATH SO WENT WITH 15 TO 20 KT SOUTHWEST WINDS FOR NOW.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-
ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 10 AM WEDNESDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 10
AM WEDNESDAY.
LM...DENSE FOG ADVISORY...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-
LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-
LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 AM WEDNESDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...9 AM THURSDAY TO 9 PM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
335 AM CST WED NOV 21 2012
.DISCUSSION...
ISSUED 315 AM CST WED NOV 21 2012
WEAK...BUT EXPANSIVE HIGH PRESSURE STRETCHING FROM THE SOUTHERN
PLAINS INTO THE NERN CONUS. LIGHT TO NON EXISTENT WINDS AND A POOL
OF LLVL MOISTURE BOTH LED TO A STUBBORN FOG BANK AND STRATUS DECK
PERSISTING THROUGHOUT MUCH OF THE DAY YESTERDAY IN IA. THIS
MORNING...THE FOG HAS SPREAD INTO ILLINOIS AND REDUCED
VISIBILITIES FOR THE MAJORITY OF THE STATE. AREAS IN THE SE ARE
RADIATING OUT RATHER EFFECTIVELY IN MOST LOCATIONS AND SOME VIS
ARE BEGINNING TO DROP AS WELL...IF NOT INTO DENSE FOG CAT. FIRST
ISSUE FOR THE FORECAST IS THE HANDLING OF THE FOG THIS
MORNING. ON THE OTHER SIDE OF THAT...THE FORECAST REMAINS THE
SAME...WITH CHANCE POPS ACCOMPANYING A SYSTEM PUSHING A FRONT
THROUGH THE MIDWEST ON THURSDAY...AND TEMPS ON THE BACKSIDE OF
THAT FRONT AS THE WARM AIR IS PUSHED BACK OUT OF THE MIDWEST.
ANOTHER SYSTEM COMING TOGETHER FOR THE FIRST PART OF THE WORK WEEK
AFTER THE HOLIDAY...WITH THE BETTER CHANCES FOR RAIN IN THE REGION
TO THE SOUTH ALONG THE OHIO RIVER VALLEY.
SHORT TERM...TODAY AND TONIGHT...
FOG IS A RATHER DIFFICULT FORECAST AS MODELS WERE NOT PICKING UP
ON THE STRATUS/FOG LAST NIGHT. A FORECAST OF PERSISTENCE WOULD
KEEP THE FOG AND CLOUDS OVER THE FA AT LEAST THROUGH MIDDAY. HAVE
EXPANDED AND EXTENDED THE DENSE FOG ADVISORY AS THE FORECAST
SOUNDINGS ARE NOT SHOWING MUCH IN THE WAY OF POTENTIAL FOR MIX OUT
UNTIL LATER IN THE DAY. TEMPERATURES GOING TO BE NEGATIVELY
IMPACTED FOR THE DAY AS THE LACK OF SUNSHINE AND MIXING GOING TO
PRECLUDE THE CHANCES TO GET UP INTO THE LOWER 60S. EXCEPTION WILL
BE ON THE EDGES OF THE STRATUS...TO THE EAST AND TO THE
SOUTH...WHERE SOME SUNSHINE MIGHT LAST MORE THAN A COUPLE HOURS
AND BOOST TEMPS A BIT HIGHER. IF THERES SUN...MIGHT GET INTO THE
UPPER 50S/LOWER 60S. WHERE THERES PERSISTENT CLOUDS AND
FOG...TEMPS WILL LIKELY STRUGGLE TO GET TO THE LOWER 50S.
LONG TERM...THURSDAY THROUGH TUESDAY...
LIGHT SOUTHERLY FLOW KICKS UP A NOTCH OR TWO TOMORROW...ASSISTING
IN WARMING THE REGION BACK UP AHEAD OF THE APPROACHING FRONT.
CLOUDS ALONG AND AHEAD OF THE FRONT WILL COUNTER THE LLVL
WAA...BUT MOS IS STILL PUSHING THE MAX TEMPS INTO THE LOW 60S.
FROPA IN THE OVERNIGHT HOURS WILL BRING THE BEST CHANCES FOR
WIDESPREAD PRECIP THU NIGHT. FRIDAY WILL START TO SEE COOLER
TEMPS...WITH DAYTIME HIGHS LOWER THAN THE PREVIOUS FEW NIGHTS
LOWS. FRIDAY WILL BE SOMEWHAT CHILLY WITH TEMPS IN THE 40S...BUT
SATURDAY WILL BE SIGNIFICANTLY COOLER WITH MAX TEMPS IN THE 30S AS
850 TEMPS DROP FROM ROUGHLY 10C ON WED AFTERNOON...TO -8C TO -10C
ON FRI NIGHT. TEMPS HAVE A CHANCE TO MODERATE SOMEWHAT FOR SUN AND
MON AS THE FLOW BECOMES QUASI ZONAL UNTIL ANOTHER SHOT OF
REINFORCING COLD AIR DROPS IN BEHIND A FRONT ON MON/MON NIGHT.
PRECIP ACCOMPANIES THE FRONT MON/MON NIGHT... AND BACK TO COOLER
TEMPS ON TUES.
HJS
&&
.AVIATION...
ISSUED 1124 PM CST TUE NOV 20 2012
PERSISTENT CLOUD COVER HAS BEEN SLOW TO CLEAR ACROSS EAST-CENTRAL
ILLINOIS THIS EVENING...HOWEVER SATELLITE LOOPS SUGGEST SKIES WILL
BE MOSTLY CLEAR AT ALL TERMINALS BY 06Z. MAIN AVIATION CONCERN
OVERNIGHT WILL BE THE DEVELOPMENT OF DENSE FOG. CURRENT
OBS/SATELLITE SHOW FOG DEVELOPING/EXPANDING EASTWARD ACROSS THE
ILLINOIS RIVER VALLEY TOWARD THE I-55 CORRIDOR. HRRR HAS HAD AN
EXCELLENT HANDLE ON THE FOG...AND SHOWS IT CONTINUING TO SPREAD
EASTWARD OVERNIGHT. STILL SOME UNCERTAINTY WHETHER DENSE FOG CAN
DEVELOP AS FAR EAST AS KCMI...SO HAVE ONLY REDUCED VISBYS THERE TO
AROUND 1SM AFTER 09Z. ELSEWHERE...HAVE BROUGHT VISBYS DOWN TO
1/4SM THROUGH 14Z. AFTER THAT...FOG WILL SLOWLY DISSIPATE
WEDNESDAY MORNING...WITH UNRESTRICTED VISBYS RETURNING AFTER 16Z.
AS HIGH PRESSURE AXIS SLIDES OFF TO THE EAST...WINDS WILL BECOME
S/SW AT 5 TO 10 KT WEDNESDAY AFTERNOON. 00Z NAM FORECAST SOUNDINGS
INDICATE THE POTENTIAL FOR MORE FOG WEDNESDAY NIGHT...HOWEVER
THINK SOUTHERLY FLOW ON THE BACK SIDE OF THE DEPARTING HIGH WILL
BE STRONG ENOUGH TO KEEP THE ATMOSPHERE SUFFICIENTLY MIXED.
BARNES
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR ILZ027>031-036>038-
040>057-061.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1131 PM CST TUE NOV 20 2012
.DISCUSSION...
922 PM CST
HAVE EXPANDED THE DENSE FOG ADVISORY TO INCLUDE THE REMAINDER OF
THE FORECAST AREA...INCLUDING ALL OF CHICAGO...AS OBSERVATIONAL
GUIDANCE CONTINUES TO FALL IN LINE WITH THE IDEAL SYNOPTIC AND
MESOSCALE PATTERNS FOR DENSE FOG.
NOT MUCH TO ADD FROM PREVIOUS REASONING IN DISCUSSIONS BELOW. THE
00Z DVN SOUNDING REVEALED A CLASSIC FOG SOUNDING GOING INTO THE
EVENING. THE AREA OF PERSISTENT DENSE FOG CENTERED ON THE
MISSISSIPPI RIVER CONTINUES TO EXPAND EASTWARD...LINING UP WITH
THE SURFACE RIDGE AXIS PERFECTLY. OFF OF LAKE MICHIGAN INTO
NORTHWEST IN/SOUTHWEST MI...DENSE FOG HAS DEVELOPED/EXPANDED
INLAND DUE LIKELY TO SLIGHTLY HIGHER MOISTURE...ALTHOUGH IT SEEMS
PATCHY TO AREAS AT TIMES BASED ON WEBCAMS AND REPORTS. AS FOR
IN-BETWEEN THESE TWO PRONOUNCED AREAS...THE ATMOSPHERE SHOULD
CONTINUE TO SATURATE AND FORECAST SOUNDINGS INDICATE DENSE FOG
FOR MUCH OF THE OVERNIGHT AND INTO WEDNESDAY MORNING. SOME CONCERN
THIS FOG COULD LAST ALL THE WAY TO NOON. NO MATTER WHAT...THIS
WILL HAVE IMPACTS ON ANY EARLY TO MID MORNING HOLIDAY TRAVELERS.
IN ADDITION...HAVE FURTHER STIFLED THE TYPICAL DIURNAL TEMPERATURE
INCREASE WEDNESDAY MORNING...AND LOWERED HIGH TEMPERATURES BY 2-3
DEGREES. THESE MAY END UP NEEDING TO BE LOWERED MORE...AS THE LATE
NOVEMBER LOW SUN ANGLE WILL HAVE SOME DIFFICULTY ERODING THIS FOG.
MTF
//PREV DISCUSSION...
628 PM CST
HAVE SPED UP THE START TIME OF THE DENSE FOG IN THE FORECAST...AND
WITH FURTHER INCREASED CONFIDENCE ON THE AREA TO MOST LIKELY BE
IMPACTED...HAVE GONE AHEAD AND ISSUED A DENSE FOG ADVISORY FOR
NORTH CENTRAL ILLINOIS AND FAR WESTERN AND NORTHERN AREAS OF THE
CHICAGO METROPOLITAN AREA. THIS MAY VERY WELL NEED TO BE EXPANDED
IN TWO TO THREE HOURS.
WINDS HAVE BECOME CALM OR LIGHT AND VARIABLE ACROSS THE ENTIRE
AREA EARLY THIS EVENING AS THE RIDGE AXIS HAS EXPANDED INTO
NORTHERN IL. DEW POINTS REMAIN ANOMALOUSLY HIGH WITH MID 40S...AND
TEMPERATURE DROPS AT A HANDFUL OF SITES HAVE BEEN AROUND OR EVEN
HIGHER THAN 10F SINCE 4 PM. THIS HAS RESULTED IN T/TD SPREADS OF
LESS THAN 5F ALREADY ACROSS NORTH CENTRAL IL. IN ADDITION..THE
AREAS OF FOG THAT PERSISTED THROUGH TODAY IN EASTERN IA/FAR
SOUTHWEST WI THAT WERE MENTIONED IN THE PRIOR DISCUSSION HAVE ONLY
BLOSSOMED SINCE SUNDOWN. VISIBILITY OBSERVATIONS IN THESE AREAS
ARE ALMOST ALL AT ONE QUARTER MILE OR LESS. SO WITH THE RIDGE AXIS
ONLY FURTHER TRANSITIONING OVER THE AREA THROUGH LATE
EVENING...WOULD EXPECT VISIBILITY TO DROP AND ESPECIALLY RAPID IN
THOSE AREAS WHERE THE PERSISTING FOG EXPANDS IN /WESTERN WINNEBAGO
AND OGLE COUNTIES BY 830 PM/. THE HRRR FORECAST VISIBILITY AGREES
WITH THIS IDEA OF EASTWARD EXPANSION THROUGH LATE EVENING AND
OVERNIGHT.
AS FOR AREAS TO THE EAST...INCLUDING MUCH OF
CHICAGOLAND...WIDESPREAD 3-6 SM VISIBILITIES EXIST. THESE
VISIBILITIES AND WEBCAMS HAVE INDICATED VERY GRADUAL VISIBILITY
REDUCTION SINCE SUNDOWN. LINGERING CLOUDS AND ASSOCIATED MOIST
LAYER AROUND 3K FT ARE LIKELY IMPAIRING FULL RADIATIONAL COOLING
SOMEWHAT...BUT DO FULLY EXPECT THESE AREAS TO COOL MORE QUICKLY
AND DENSE FOG AT LEAST IN PLACES TO DEVELOP. AREAS NEAR THE LAKE
MAY ACTUALLY BECOME MORE FAVORED TO SEE THE FOG MORE QUICKLY DUE
TO A LIGHT BUT MOIST ONSHORE COMPONENT.
IMPROVEMENT IN THE FOG ON WEDNESDAY MORNING MAY BE EXTREMELY
SLOW...WITH SOME AREAS OF FOG LASTING INTO THE EARLY AFTERNOON
GIVEN WHAT OCCURRED UPSTREAM IN EASTERN IOWA TODAY AND JUST THE
CLIMATOLOGY OF THIS TIME OF YEAR. WILL FURTHER ASSESS THIS WITH
00Z GUIDANCE.
MTF
//PREV DISCUSSION...
256 PM CST
TONIGHT THROUGH WEDNESDAY...
GREATEST CONCERN FOR TONIGHT RESIDES WITH THE EXPECTED DEVELOPMENT
OF FOG...TRANSITIONING INTO AREAS OF DENSE FOG OVERNIGHT. THE
OTHER CONCERN IS THAT ONE OF THE BUSIEST TRAVEL DAYS OF THE YEAR
WILL HAVE A SLOW START GIVEN THE EXPECTED DEVELOPMENT OF FOG.
LOOKING UPSTREAM ACROSS EASTERN IOWA FOG HAS LINGERED INTO THIS
AFTERNOON...WITH A FEW LOCATIONS STILL SEEING VSBYS DOWN AROUND 1 TO
2 MILES. THIS AFTN HAS SEEN ALMOST NO MIXING WITH LGT WINDS
GENERALLY LESS THAN 5 MPH...AND DEW POINTS HOLDING UP IN THE MID 40S
FOR MANY LOCATIONS OF NORTHERN IL/NORTHWEST IN. HIGH PRESSURE WILL
REMAIN OVERHEAD TONIGHT...WHICH WILL AID IN DECENT RADIATIONAL
COOLING SHORTLY AFTER SUNSET. THIS ALL POINTS TOWARDS A REPEAT NIGHT
OF AREAS OF FOG AND POTENTIALLY AREAS OF DENSE FOG. OVERNIGHT LOWS
WILL COOL INTO THE LOW 40S...WITH THE EXCEPTION OF AREAS ADJACENT TO
LAKE MICHIGAN WHERE TEMPS MAY HOLD IN THE MID 40S.
ONCE THE FOG DOES DEVELOP IT WILL MOST LIKELY LINGER INTO WED
MORNING...POSSIBLY THROUGH MIDDAY. GIVEN THE SCENARIO OF WHAT HAS
TRANSPIRED ACROSS EASTERN IOWA...COULD SEE THE DENSE FOG LIFT BY
MID-MORNING THEN PATCHY FOG THROUGH NOON. THIS WILL RESULT IN
TEMPERATURES BEING SLOW TO WARM...THUS HAVE SLOWED THE RATE OF CLIMB
UNTIL MIDDAY. THROUGHOUT THE MORNING HOURS TEMPS WILL REMAIN IN THE
LOW/MID 40S...THEN BY MIDDAY AND IMPROVING VSBYS OR BURNING OFF
FOG...TEMPS WILL BEGIN TO CLIMB RAPIDLY INTO THE UPR 50S AND
POSSIBLY 60 DEG IN A FEW LOCATIONS. OTHERWISE SKIES WILL BECOME
MOSTLY CLEAR IN THE AFTERNOON HOURS.
CONFIDENCE...HIGH.
CONFIDENCE ON AREAS OF DENSE FOG...MEDIUM/HIGH.
THANKSGIVING...
500MB RIDGE REMAINS OVERHEAD...WITH A POTENT THERMAL RIDGE AT 850MB
OF 10 TO 12 DEG C. A FEW ENSEMBLE MEMBERS SUGGEST THAT 850MB TEMPS
COULD BE SLIGHTLY WARMER TO 14 DEG C. THE BETTER PRESSURE GRADIENT
REMAINS DISPLACED TO THE NORTHWEST OF THE REGION...WHICH IS THE AREA
THAT WILL SEE THE STRONGEST WARM AIR ADVECTION. EITHER WAY...IT
APPEARS THANKSGIVING WILL END UP BEING A RATHER WARM DAY WITH TEMPS
LIKELY TO REACH THE LOW 60S. PLUMES CONTINUE TO INDICATE A HIGH
CONFIDENCE THAT TEMPS WILL EASILY PUSH TO 60 DEGREES BY NOON. THE
LARGEST CAVEAT COULD BE THAT INCREASED MOISTURE APPEARS TO BE
PROGGED TO POOL ALONG THE BOUNDARY INTO THE MID-MISSISSIPPI
VALLEY...WHICH COULD PUSH CLOUDS OVERHEAD BY LATE MORNING. THIS
MAINLY WILL AFFECT THE WESTERN HALF OF THE CWFA. IN ADDITION HAVE
OVERSPREAD A SLIGHT CHC OF PRECIP BY MIDDAY ALONG AND NORTH OF A LA
SALLE TO CRYSTAL LAKE LINE. THEN ADDITIONAL MOISTURE CONTINUES TO
POUR INTO THE CWFA BY MID-AFTERNOON/EVENING...SO HAVE MAINTAINED
MENTION OF SLT CHC OF RA.
CONFIDENCE IN TEMPS...HIGH.
CONFIDENCE IN PRECIP...LOW.
FRIDAY THROUGH MONDAY...
ENSEMBLES THROUGH THE EXTENDED PERIODS CONTINUE TO SHOW MINIMAL
SPREAD IN ENVELOPE OF SOLUTIONS...LEADING TO THE INCREASED
CONFIDENCE THAT A PATTERN CHANGE IS UPON US. FRIDAY WILL KICK OFF
THE EXTENDED WITH A TASTE OF COLDER AIR...HOWEVER WHAT APPEARS TO BE
TAKING SHAPE FOR MID/LATE NEXT WEEK WILL BE MUCH MORE SIGNIFICANT AS
THE CALENDAR APPROACHES THE FIRST OF DECEMBER.
GUIDANCE CONTINUES TO PROG FRONTAL PASSAGE FOR THE FIRST HALF OF
FRI...POSSIBLY PRIOR TO DAYBREAK. VERY TIGHT PRESSURE GRADIENT IS
ALSO POISED TO ARRIVE BEHIND THE FRONTAL PASSAGE FRI...RESULTING IN
BREEZY CONDITIONS. WITH COOLER AIR STEADILY ADVECTING IN FROM THE
NORTHWEST AS A RESULT OF AN 850MB THERMAL TROUGH OF -10 TO -14 DEG
C...MAX TEMPS FRI COULD BE ACHIEVED PRIOR TO MID-MORNING. THEN IT
APPEARS FALLING TEMPS WILL OCCUR EARLY IN THE AFTERNOON. AT THIS
TIME IT APPEARS A DRY WEDGE WILL OCCUR FRI...SHIFTING ANY MOISTURE
EAST OF THE CWFA. THEN THE TRANSITION TOWARDS LAKE EFFECT PRECIP
DEVELOPS FRI AFTERNOON THROUGH SATURDAY EVENING...WHICH FORTUNATELY
WITH A STRONG WEST/NORTHWEST FLOW THIS PRECIP WILL BE DISPLACED
DOWNSTREAM ACROSS LOWER MICHIGAN AND PERHAPS PORTIONS OF NORTHWEST
INDIANA.
SAT/SUN WILL SEE ANTI-CYCLONIC FLOW PUSH BACK OVERHEAD WITH DRY
WEATHER EXPECTED THROUGH THE WEEKEND INTO EARLY MON. 500MB TROUGH
PIVOTS EAST WITH A RELATIVELY FLAT OR SEMI-ZONAL FLOW SUN/MON. SAT
HIGH TEMPS WILL STRUGGLE TO WARM INTO THE MID/UPR 30S. SUN/MON WILL
BEGIN TO WARM MARGINALLY INTO THE LOW 40S. THIS ALL APPEARS TO BE
TEMPORARY AS THE DEVELOPMENT OF A BLOCKING PATTERN BEGINS TO TAKE
SHAPE OVER ALASKA AND THE NORTH ATLANTIC...WHICH WILL ULTIMATELY
ALLOW MUCH COLDER AIR TO ARRIVE INTO CENTRAL CANADA MID/LATE NEXT
WEEK FROM SIBERIA.
CONFIDENCE...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* DENSE FOG THROUGH THE MORNING...IMPROVING TO MVFR VSBY BY NOON.
* REDUCED VERTICAL VISIBILITIES OF 100 FT THROUGH MID MORNING
BECOMING 100 FT CIGS THROUGH NOON.
JEE
//DISCUSSION...UPDATED 06Z...
BROAD HIGH PRESSURE HAS SETTLED OVER THE REGION WITH WEAK TO CALM
WINDS. CLEAR SKIES HAVE ALLOWED FOR EFFICIENT RADIATIONAL COOLING
AND DENSE FOG DEVELOPMENT. MONITORING TWO AREAS OF DENSE FOG. THE
FIRST IS WEST OF A JVL TO RFD TO PIA LINE. THE SECOND IS EAST OF A
GYY TO IKK LINE. AT ITS CURRENT SPEED...THE WESTERN REGION OF
DENSE FOG WILL MOVE OVER ORD AND MDW BY 17Z. STATIONS UPSTREAM
HAVE SUDDENLY DROPPED FROM 2 SM TO 1/4 SM OR LESS AS THE AREA OF
DENSE FOG MOVES OVERHEAD. THINKING ORD AND MDW WILL NOT DROP TO
LESS THAN 1/4 SM. AS VSBY SETTLES IN ALSO EXPECTING VERTICAL
VISIBILITIES TO BE REDUCED TO 100 FT OR LESS.
SOUTHWEST FLOW WILL SLOWLY INCREASE TOMORROW MORNING...SLOWER THAN
PREVIOUSLY INDICATED. AS SUCH MOVED TIME OF MVFR VSBY IMPROVEMENT
BACK TO NOON. THE FOG WILL NOT DISSIPATE OR IMPROVE UNTIL BOUNDARY
LAYER MIXING GETS GOING. AS FOG MIXES OUT...EXPECTING IT TO RISE
RESULTING IN A PERIOD OF BKN001 CIGS MID WEDNESDAY MORNING THROUGH
ABOUT NOON. EXPECTING TO RETURN TO VFR BY MID WEDNESDAY AFTERNOON.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN CIG VALUES.
* MEDIUM-HIGH CONFIDENCE IN VSBY...1/4SM LIKELY...M1/4SM PSBL.
* MEDIUM-HIGH CONFIDENCE OF TIMING OF VSBY/CIG IMPROVEMENT.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...GUSTY SOUTHERLY WINDS AND CHANCE OF SHRA...OTHERWISE
VFR.
FRIDAY...MVFR POSSIBLY EARLY...GUSTY NW WINDS...OTHERWISE VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...SLIGHT CHANCE SHRA...OTHERWISE VFR.
RODRIGUEZ
&&
.MARINE...
228 PM CST
A VERY WEAK GRADIENT IS IN PLACE ACROSS THE WESTERN GREAT LAKES
REGION THIS AFTERNOON RESULTING IN LIGHT AND VARIABLE WINDS ACROSS
LAKE MICHIGAN. AREAS OF FOG ARE EXPECTED ACROSS PORTIONS OF THE LAKE
TONIGHT INTO EARLY WEDNESDAY. WINDS SHOULD GRADUALLY MOVE TOWARDS A
SOUTHERLY DIRECTION OVERNIGHT AS LOW PRESSURE MOVES ACROSS THE
CANADIAN PRAIRIES AND OVER HUDSON BAY. THE GRADIENT TIGHTENS
PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE WHERE WINDS WILL
INCREASE TO AROUND 30 KT BY WEDNESDAY EVENING. WEDNESDAY NIGHT INTO
THURSDAY...ANOTHER AREA OF LOW PRESSURE DEVELOPS OVER THE NORTHERN
PLAINS AND MOVES EAST TOWARDS LAKE SUPERIOR BY THURSDAY EVENING.
WINDS IN ADVANCE OF THIS SYSTEM WILL CONTINUE AROUND 30 KT THROUGH
THE DAY THURSDAY. AFTER A COLD FRONT SWEEPS ACROSS THE LAKE THURSDAY
NIGHT...STRONG COLD ADVECTION WILL ALLOW NORTHWEST WINDS TO INCREASE
TO GALES OF 35 TO 40 KT FRIDAY. RIDGING SHOULD MOVE ACROSS THE LAKE
EARLY IN THE WEEKEND ALLOWING WINDS TO DIMINISH...BUT BEYOND
SATURDAY...MODELS CONTINUE TO HAVE SIGNIFICANT DIFFERENCES LEADING
TO VERY LOW CONFIDENCE IN THE FORECAST LATE THIS WEEKEND INTO EARLY
NEXT WEEK. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-
ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 10 AM WEDNESDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 10
AM WEDNESDAY.
LM...DENSE FOG ADVISORY...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-
LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-
LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 AM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1124 PM CST TUE NOV 20 2012
.DISCUSSION...
ISSUED 605 PM CST TUE NOV 20 2012
CLOUDS WILL CONTINUE TO SLOWLY CLEAR FROM NORTHWEST TO SOUTHEAST
THIS EVENING...WITH MOSTLY CLEAR SKIES EXPECTED ACROSS THE
BOARD AFTER MIDNIGHT. WITH CLEAR SKIES AND NEARLY CALM WINDS
BENEATH A SURFACE RIDGE AXIS...EXCELLENT RADIATIONAL COOLING
CONDITIONS WILL ALLOW SURFACE-BASED SATURATION TO OCCUR OVERNIGHT.
00Z/6PM IR SATELLITE IMAGERY SHOWS A PERSISTENT AREA OF DENSE FOG
ALONG THE MISSISSIPPI RIVER BEGINNING TO SLOWLY SPREAD EASTWARD.
20Z HRRR HAS AN EXCELLENT HANDLE ON THE FOG AREA...AND SHOWS IT
EXPANDING FURTHER EASTWARD INTO THE ILLINOIS RIVER VALLEY BETWEEN
03Z/9PM AND 06Z/12AM...THEN FURTHER EAST TO THE I-55 CORRIDOR
AFTER MIDNIGHT. HAVE THEREFORE ISSUED A DENSE FOG ADVISORY FOR ALL
LOCATIONS ALONG AND WEST OF A BLOOMINGTON-NORMAL TO TAYLORVILLE
LINE TONIGHT INTO WEDNESDAY MORNING. AM EXPECTING VISBYS TO DROP
TO LESS THAN 1/4 MILE AT TIMES...IMPACTING THE EARLY MORNING
COMMUTE. FURTHER EAST...FORECAST SOUNDINGS SHOW SLIGHTLY DRIER AIR
AT LOW-LEVELS...SUGGESTING FOG WITH VISBYS GENERALLY IN THE 1 TO 3
MILE RANGE TOWARD DAWN. UPDATED ZONE FORECAST HAS ALREADY BEEN
ISSUED.
BARNES
&&
.AVIATION...
ISSUED 1124 PM CST TUE NOV 20 2012
PERSISTENT CLOUD COVER HAS BEEN SLOW TO CLEAR ACROSS EAST-CENTRAL
ILLINOIS THIS EVENING...HOWEVER SATELLITE LOOPS SUGGEST SKIES WILL
BE MOSTLY CLEAR AT ALL TERMINALS BY 06Z. MAIN AVIATION CONCERN
OVERNIGHT WILL BE THE DEVELOPMENT OF DENSE FOG. CURRENT
OBS/SATELLITE SHOW FOG DEVELOPING/EXPANDING EASTWARD ACROSS THE
ILLINOIS RIVER VALLEY TOWARD THE I-55 CORRIDOR. HRRR HAS HAD AN
EXCELLENT HANDLE ON THE FOG...AND SHOWS IT CONTINUING TO SPREAD
EASTWARD OVERNIGHT. STILL SOME UNCERTAINTY WHETHER DENSE FOG CAN
DEVELOP AS FAR EAST AS KCMI...SO HAVE ONLY REDUCED VISBYS THERE TO
AROUND 1SM AFTER 09Z. ELSEWHERE...HAVE BROUGHT VISBYS DOWN TO
1/4SM THROUGH 14Z. AFTER THAT...FOG WILL SLOWLY DISSIPATE
WEDNESDAY MORNING...WITH UNRESTRICTED VISBYS RETURNING AFTER 16Z.
AS HIGH PRESSURE AXIS SLIDES OFF TO THE EAST...WINDS WILL BECOME
S/SW AT 5 TO 10 KT WEDNESDAY AFTERNOON. 00Z NAM FORECAST SOUNDINGS
INDICATE THE POTENTIAL FOR MORE FOG WEDNESDAY NIGHT...HOWEVER
THINK SOUTHERLY FLOW ON THE BACK SIDE OF THE DEPARTING HIGH WILL
BE STRONG ENOUGH TO KEEP THE ATMOSPHERE SUFFICIENTLY MIXED.
BARNES
&&
.PREV DISCUSSION...
ISSUED 307 PM CST TUE NOV 20 2012
MAIN CONCERNS THIS FORECAST PACKAGE INVOLVE PCPN CHANCES FOR
THURSDAY AND THURSDAY NIGHT WITH MILD TEMPS...AND CHC PCPN FOR
MONDAY THROUGH TUESDAY...ALONG WITH COOLER TEMPS THROUGH THE
EXTENDED PERIOD. MODELS REMAIN RELATIVELY SIMILAR IN THE SHORT
TERM BUT DIFFER SLIGHTLY WITH THE TIMING AND INTENSITY OF THE
SHORT WAVE COMING THROUGH THE AREA THUR AND THUR NIGHT...ALONG
WITH AMOUNT OF PCPN EXPECTED WITH THE FRONT. BELIEVE A BLEND OF
THE MODELS LOOKS BEST IN THE SHORT TERM. MODELS IN THE EXTENDED
PERIOD ALSO LOOK SIMILAR WITH DIFFERENCES BETWEEN THE ECMWF AND
THE GFS BEING WITH THE LOCATION AND STRENGTH OF A SFC LOW MOVING
NORTHEAST OUT OF THE SOUTHERN PLAINS EARLY NEXT WEEK.
SHORT TERM...TONIGHT THROUGH FRIDAY
HIGH PRSS WILL DRIFT ACROSS THE AREA TONIGHT...BRINGING VERY LIGHT
WINDS. DEWPOINTS HAVE INCREASED DURING THE DAY AND WITH AN
INVERSION EXPECTED TO SETUP THIS EVENING...DENSE FOG SEEMS
POSSIBLE. HOWEVER...MOST OF CWA HAS HAD LOTS OF SUNSHINE THIS
AFTERNOON AND BELIEVE THE SUN HAS BEEN ABLE TO BURN OFF SOME OF
THE LOW LEVEL MOISTURE. MODELS DIFFER ON WHAT RESULTING DEWPOINTS
WILL BE IN THE MORNING AS TEMPS FALL. BECAUSE OF SUNSHINE THIS
AFTERNOON AM NOT CONVINCED THAT DENSE FOG WILL OCCUR...BUT DO
THINK THERE WILL BE FOG OVERNIGHT. SO WILL HAVE AREAS OF FOG IN
THE FORECAST FOR OVERNIGHT AND MORNING HOURS TILL ABOUT 15Z. COULD
BE SOME ISOLATED/LOCALIZED AREAS WHERE FOG BECOMES DENSE...BUT NOT
ASSURED ENOUGH TO ADD TO FORECAST. WILL LET EVENING SHIFT EVALUATE.
AS HIGH PRSS MOVES TO THE SOUTHEAST TOMORROW...AM EXPECTING DRY
AND WARM WEATHER TOMORROW AND THURSDAY. THEN A FRONT WILL MOVE
INTO THE AREA LATE THURSDAY AND INTO THURSDAY NIGHT. BELIEVE
MOISTURE WILL STILL BE LIMITED BUT ENOUGH THAT PCPN CHANCES WILL
HAVE TO BE INCREASED FOR THURSDAY NIGHT. NAM IS DRY THROUGH THE
PERIOD...WHILE GFS HAS LOTS OF PCPN. SO WILL LIMITED POPS TO JUST
UNDER LIKELY GIVEN DIFFERENCES AND LIMIT MOISTURE EXPECTED. CLOUDS
AND PCPN MAY LINGER IN SOUTHEAST FRIDAY SO HAVE INCLUDED SLIGHT
CHC IN SOUTHEAST FOR FRI...MAINLY IN THE MORNING.
TEMPS WILL REMAIN ABOVE NORMAL FOR TWO MORE DAY AHEAD OF THE FRONT
BUT THEN FALL BEHIND THE FRONT. TEMPS FRIDAY EXPECTED TO BE IN THE
40S WITH AROUND 50 IN THE SOUTHEAST. THESE TEMPS WILL BE SLIGHTLY
BELOW NORMAL.
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY
COOLER HIGH PRSS WILL BUILD INTO THE REGION FOR THE WEEKEND AND
TEMPS WILL BE COOLER THAN NORMAL THROUGH THE EXTENDED PERIOD.
ANOTHER FRONTAL SYSTEM WILL MOVE INTO THE AREA FOR BEGINNING OF
NEXT WEEK BUT MODELS DIFFER ON TIMING/POSITION/STRENGTH OF THE
FRONT/SYSTEM. HOWEVER...MODELS DO HAVE SOME PCPN FORECAST FOR MON
THROUGH TUE. SO REAL QUESTION WOULD BE PRECIP TYPE THROUGH THAT
TIME FRAME. BASED ON TRACK OF THE LOW PRSS AREA...MOST PCPN SHOULD
REMAIN ACROSS THE SOUTHERN TWO THIRDS OF THE CWA. WITH TEMPS
FALLING TO BELOW FREEZING AT NIGHT...WILL HAVE PCPN TYPE OF
RAIN OR SNOW AND THEN ALL SNOW OVER PARTS OF THE AREA. THIS COULD
CHANGE IF FURTHER NORTH TRACK FROM ECMWF FORECAST HOLDS TRUE
THROUGH REST OF THE WEEK. LOTS OF TIME TO WATCH AND SEE.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM CST WEDNESDAY FOR ILZ027>031-
036>038-040>043-047>053.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1141 PM CST TUE NOV 20 2012
.UPDATE...
VIS/FOG SATELLITE IMAGERY SHOWS LOW STRATUS AND FOG HAS ENTERED
FORECAST AREA FROM THE EAST WITH OBS INDICATING VISIBILITIES QUICKLY
DROPPING TO NEAR ZERO ONCE IT BEGINS. HAVE ONLY INCLUDED TWO TIERS
OF ERN COUNTIES FOR A START EXPECTING WESTWARD PROGRESSION TO
EVENTUALLY CEASE WHERE IT ENCOUNTERS DRIER AIRMASS. LATEST RAP
1000-950MB RH DROPS QUICKLY TO AROUND 50 PERCENT ALONG THE I35
CORRIDOR.
&&
.SHORT TERM /TONIGHT/...
SFC HIGH CENTERED FROM SRN IA SOUTHWESTWARD TO SLIDE EAST SOUTHEAST
TONIGHT...WITH SOUTHERLY FLOW AND WAA KICKING IN ALOFT. MOSTLY CLEAR
SKIES EXPECTED TONIGHT WITH THE EXCEPTION OF THE FAR EAST...WHERE
LOW STRATUS/FOG THAT IS CURRENTLY ACROSS SOUTHEASTERN IOWA EXPECTED
TO BUILD BACK WEST/NORTHWARD THIS EVENING. THEREFORE LOW CLOUDS/FOG
POSSIBLE FROM WATERLOO TO MARSHALLTOWN TO OTTUMWA OVERNIGHT...BASED
ON THE HRRR OUTPUT FOR LOW CLOUDS. AS SFC RIDGE AXIS PUSHES THROUGH
THE AREA AND WAA/SOUTHERLY FLOW INCREASES EXPECT MIN TEMPS TO START
LEVELING OFF/POSSIBLY WARMING TOWARD SUNRISE.
.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL SHIFT OFF TO THE SOUTHEAST ON WEDNESDAY AS A
BROAD AREA OF HIGH PRESSURE MOVES INTO THE DAKOTAS. THIS WILL
INCREASE THE SOUTHERLY FLOW INTO IOWA AS THE THERMAL RIDGE LEANS
INTO THE STATE. THESE CONDITIONS ALONG WITH VERY DRY AIR WILL BE
CONDUCIVE TO GOOD WARMING. AN INVERSION NEAR 900 MB APPEARS TO BE A
LIMITING FACTOR FROM ACHIEVING RECORD HIGH TEMPERATURES IN THE LOWER
70S HOWEVER EVEN IF THE INVERSION HOLDS...SUPER ADIABATIC LAPSE NEAR
SURFACE SHOULD PUSH READINGS INTO THE MID TO UPPER 60S. THE THERMAL
RIDGE STRENGTHENS WEDNESDAY NIGHT WITH SOUTHERLY WINDS CONTINUING.
LOWS WILL BE WELL INTO THE 40S AT MOST LOCATIONS. THURSDAY WILL HAVE
A WARM START WITH A COLD FRONT EXPECTED TO PASS THROUGH CENTRAL IOWA
DURING THE AFTERNOON. AN SHORT WAVE WILL LIFT UP THROUGH THE
SOUTHWEST FLOW AHEAD OF THE BOUNDARY AND WILL BRING THE CHANCE FOR A
FEW SHOWERS OVER THE FAR SOUTHEAST. THE NMM AND ARW BASED MODELS ARE
FARTHER SOUTHEAST WITH THIS SYSTEM THOUGH THE ECMWF AND GFS AFFECT
IOWA MORE. GENERALLY ANY PRECIPITATION WILL BE LIGHT. THIS SYSTEM
COULD BRING AN INCREASE IN CLOUDS AND MAY LIMIT TEMPERATURES A BIT.
CENTRAL AND SOUTHEAST IOWA SHOULD REACH THE 60S BEFORE THE COLD
FRONT PASSES THROUGH. STRONGER COLD ADVECTION NEAR 850 MB WILL
ENHANCE MIXING BEHIND THE FRONTAL BOUNDARY WITH INCREASING
SUBSIDENCE AIDING MOMENTUM TRANSFER OF WINDS TO THE SURFACE. MIXED
LAYER WINDS OF 25 TO 35 KTS SHOULD PUSH SUSTAINED WINDS TO NEAR WIND
ADVISORY CRITERIA MAINLY OVER THE NORTH AND WEST.
ANOTHER SURGE OF COLD ADVECTION WILL DROP SOUTH THURSDAY NIGHT.
FRIDAY WILL BE BLUSTERY AND COLD WITH BREEZY NORTHWEST WINDS. HIGHS
WILL GENERALLY BE IN THE LOW TO MID 30S. HIGH PRESSURE MOVES ACROSS
FRIDAY NIGHT. CURRENTLY HAVE LOWS A FEW DEGREES ABOVE MOS GUIDANCE
FOR POTENTIAL MID TO HIGH LEVEL CLOUDS WITH INCREASING THETA-E
ADVECTION THROUGH THOSE LEVELS. MINOR MODERATION SATURDAY INTO
SUNDAY. A STRONGER COLD FRONT IS DUE TO ARRIVE MONDAY AND LEAD TO A
COLD START TO NEXT WEEK. THE EXTENDED WILL BE MOSTLY DRY WITH THE
POTENTIAL FOR VERY LIGHT RAIN OR SNOW EARLY NEXT WEEK.
&&
.AVIATION...21/06Z
LIFR STRATUS AND FOG IS CURRENT ALONG AND EAST OF AN KALO-KOOA-KOTM
LINE AND HAS MOVED LITTLE RECENTLY. CIRRUS MOVING ACROSS FORECAST
AREA HAS DECREASE RATE OF SURFACE COOLING. 21Z HRRR IS DEPICTING
REALITY QUITE WELL AND ONLY SPREADS LIFR A BIT FARTHER WESTWARD
OVERNIGHT. KEPT IT OUT OF KDSM AND KMCW FOR THE TIME WITH 04Z RAP
SHOWING LOWER 50MB RH IN THESE AREAS. CONDITIONS WILL LIKELY EITHER
BE VFR OR LIFR WITH LITTLE IN BETWEEN. REGARDLESS EXPECT VFR
RETURNING TO ALL SITES BY 15-16Z WED AS SLY WINDS CONTINUE TO
GRADUALLY INCREASE WITH MIXING.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY UNTIL 900 AM
BUTLER-BREMER-GRUNDY-BLACK HAWK-MARSHALL-TAMA-JASPER-POWESHIEK-
MARION-MAHASKA-MONROE-WAPELLO-APPANOOSE-DAVIS
&&
$$
SHORT TERM...MJB
LONG TERM...DONAVON
AVIATION...SMALL
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
342 AM CST WED NOV 21 2012
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
341 AM CST WED NOV 21 2012
AT 3 AM...DENSE FOG WAS REDUCING VISIBILITIES TO A QUARTER MILE OR
LESS GENERALLY EAST OF A LINE FROM MENOMINEE WISCONSIN TO OELWEIN
IOWA. WITH TEMPERATURES AT OR BELOW FREEZING ACROSS MONROE...
JUNEAU...ADAMS...JACKSON...AND CLARK COUNTIES THERE IS SOME
CONCERN THAT SOME LIGHT ICING IS OCCURRING. THIS COULD MAKE THE
MORNING COMMUTE HAZARDOUS. AS THE WINDS INCREASE THIS MORNING...THE
FOG WILL BEGIN TO DISSIPATE BETWEEN 15Z AND 17Z IN CENTRAL WISCONSIN
AND ON THE BLUFF TOPS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA.
MODEL SOUNDINGS SUGGEST THAT THE MISSISSIPPI AND WISCONSIN RIVER
VALLEYS WILL BE THE LAST TO CLEAR /BETWEEN 16Z AND 18Z/. FOR
SIMPLICITY...SET THE EXPIRATION TIME OF THE DENSE FOG ADVISORY AT
18Z. THIS WILL MAKE IT EASIER TO CLEAR OUT THE COUNTIES AS THE
VISIBILITIES IMPROVE THIS MORNING.
FOR THIS AFTERNOON...THE 21.00Z MODELS ARE IN GOOD AGREEMENT THAT
SKIES WILL BE MOSTLY SUNNY WHICH WILL ALLOW THE AREA TO MIX UP
INTO THE 950 TO 925 MB RANGE. THE DEEPEST MIXING WILL OCCUR
OUTSIDE OF THE MISSISSIPPI AND WISCONSIN RIVER VALLEYS. MANY AREAS
SOUTH OF THE INTERSTATE 94 CORRIDOR WILL WARM INTO THE LOWER AND
MID 60S...AND INTO THE MID AND UPPER 50S NORTH OF THIS INTERSTATE.
DUE TO THE FOG HOLDING ON LONGER /WHICH LEADS TO LESS MIXING/...THE
MISSISSIPPI AND WISCONSIN RIVER VALLEYS WILL LIKELY SEE THEIR HIGH
TEMPERATURES ONLY TOP OUT AROUND 60 DEGREES.
FOR TONIGHT...A TIGHT PRESSURE SURFACE GRADIENT WILL KEEP THE
SOUTH WINDS IN THE 10 TO 20 MPH RANGE. THIS WILL KEEP THE BOUNDARY
LAYER WELL MIXED...THUS PREVENTING A NOCTURNAL INVERSION FROM
FORMING. AS A RESULT...THE TEMPERATURES WILL ONLY FALL INTO THE
MID AND UPPER 40S.
ON THANKSGIVING DAY...A COLD FRONT WILL MOVE EAST THROUGH
SOUTHEAST MINNESOTA AND NORTHEAST IOWA DURING THE MORNING...AND
WESTERN WISCONSIN DURING THE AFTERNOON. THERE WILL BE ENOUGH
SUNSHINE FOR TEMPERATURES TO CLIMB INTO THE 55 TO 60 DEGREE RANGE...
AND THEN TEMPERATURES WILL FALL INTO THE MID AND UPPER 30S FOR
NORTHEAST IOWA AND SOUTHEAST MINNESOTA...AND IN THE LOWER AND
MID 40S FOR WESTERN WISCONSIN.
FOR THURSDAY NIGHT INTO FRIDAY...A STRONG SHORT WAVE TROUGH WILL
MOVE ACROSS NORTHERN MINNESOTA AND NORTHERN WISCONSIN. THIS SYSTEM
WILL PRODUCE MEASURABLE SNOW ACROSS THESE AREAS. THERE MAY BE EVEN
A DUSTING OF SNOW ACROSS TAYLOR COUNTY. WITH THE BUFKIT MODEL
SOUNDINGS SUGGESTING THAT THERE WILL BE STEEP 950 TO 850 MB LAPSE
RATES INCLUDED FLURRIES DURING THE OVERNIGHT AND ON FRIDAY FOR THE
REST OF THE AREA. EARLY RISERS FOR THE BLACK FRIDAY SALES WILL
ENCOUNTER WIND CHILLS RANGING FROM 10 TO 20 DEGREES.
.LONG TERM...SATURDAY THROUGH TUESDAY
341 AM CST WED NOV 21 2012
ON SATURDAY NIGHT...THE 21.00Z MODELS SUGGEST THAT A COLD FRONT
WILL MOVE EAST THROUGH THE FORECAST AREA. WITH THE 280 TO 270K
ISENTROPIC CONDENSATION PRESSURE DEFICITS RUNNING FROM 50 TO
100 MB AND THE SOUNDINGS SHOWING DRY AIR BELOW 8K FEET...KEPT THIS
PERIOD DRY FOR NOW.
FROM MONDAY NIGHT INTO TUESDAY...BOTH THE GFS AND ECMWF
DETERMINISTIC MODELS ARE SHOWING THE POTENTIAL FOR SOME MEASURABLE
SNOW TO FALL ACROSS THE AREA AS A LOW PRESSURE SYSTEM MOVES
FROM THE MID MISSISSIPPI RIVER VALLEY INTO THE EASTERN GREAT
LAKES. WHILE THESE MODELS ARE IN GOOD AGREEMENT THE 00Z GFS
ENSEMBLE MEMBERS SHOWED QUITE A FEW DIFFERENT SCENARIOS AMONG ITS
12 FAMILY MEMBERS. SOME OF THEM WERE IN AGREEMENT WITH THE
DETERMINISTIC GFS. MEANWHILE OTHERS SUGGESTED THAT THIS LOW WOULD
REMAIN WEAK AND STAY OVER THE SOUTHEAST UNITED STATES OR IT WOULD
TRACK FURTHER WEST WHICH WOULD RESULT IN MIXED PRECIPITATION. EVEN
THE 16 RUNS OF GEM SHOWED QUITE A FEW DIVERSE 500 MB PATTERNS. ALL
OF THIS LEADS TO LITTLE CONFIDENCE WITH THIS TIME PERIOD...SO KEPT
PRECIPITATION CHANCES AROUND 20 PERCENT.
&&
.AVIATION...THROUGH 06Z THURSDAY
1136 PM CST TUE NOV 20 2012
LATEST RAP CONTINUES TO SHOW THAT THE LOW LEVEL MOISTURE REMAINS
TRAPPED BELOW THE SUBSIDENCE INVERSION AT KLSE THROUGH MOST OF THE
MORNING...AND THEN THIS MOISTURE MIXES OUT QUICKLY AS THE GRADIENT
INCREASES. DUE TO THIS...EXTENDED THE LIFR CEILINGS AND
VISIBILITIES FROM 21.07Z TO 21.17Z. IN THE HIGHER ELEVATIONS
ALONG THE MISSISSIPPI AND WISCONSIN...AND IN CENTRAL WISCONSIN
EXPECT THAT THE DENSE FOG WILL DISSIPATE QUICKLY BETWEEN 21.16Z
AND 21.18Z. ONCE THE INVERSION BREAKS EXPECT VFR CEILINGS AND
VISIBILITIES FOR THE REMAINDER OF THIS TIME PERIOD.
ORIGINALLY THOUGHT THAT THE LOW CEILINGS AND VISIBILITIES MAY GET
INTO KRST...BUT WITH THE DENSE CIRRUS NOW OVERHEAD AND WINDS
NEAR 10 KNOTS EXPECT THAT THE RADIATIVE COOLING MAY HAVE SLOWED
ENOUGH TO PREVENT THIS FROM OCCURRING. WITH THIS SAID...THE
VISIBILITIES WILL LIKELY BECOME MVFR DUE TO HAZE BETWEEN 21.09Z
AND 21.17Z. OTHERWISE...BOTH THE CEILINGS AND VISIBILITIES SHOULD
BE VFR THROUGH THE REMAINDER OF THE PERIOD.
&&
.CLIMATE...
341 AM CST SUN NOV 18 2012
RECORD HIGH TEMPERATURES FOR TODAY/21ST AND THURSDAY/22ND. COOP
SITES ARE 7 AM-7 AM HIGHS...THUS 22ND HIGHS ARE 21.12Z TO 22.12Z.
LA CROSSE AND ROCHESTER ARE THE ONLY NON-COOP SITES.
FORECAST HIGH TEMPERATURES SUGGEST SOME OF THE RECORDS BELOW MAY
BE TIED OR BROKEN.
LOCATION TODAY/21ST THURSDAY/22ND
LA CROSSE WI 72/1990 59/1963
SPARTA WI 65/1990 70/1990
MEDFORD WI 59/1913 65/1990
LANCASTER WI 66/2003 66/1898
MAUSTON WI 67/2003 66/1990
ROCHESTER MN 69/1990 65/1913
AUSTIN MN 70/1990 58/1966
WINONA DAM 5A MN 60/2003 60/2001
WABASHA MN 61/1908 59/1908
CHARLES CITY IA 71/1990 62/1966
OELWEIN IA 71/1990 62/1966
DECORAH IA 71/1990 62/1908
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
341 AM CST WED NOV 21 2012
WI...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR WIZ017-029-032>034-
041>044-053>055-061.
MN...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR MNZ079-088-096.
IA...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR IAZ010-011-029-030.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...BOYNE
CLIMATE......JONES/DB/AJ/BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1137 PM CST TUE NOV 20 2012
.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT
601 PM CST TUE NOV 20 2012
MAIN FORECAST CONCERN IS ON CLOUDS/FOG POTENTIAL TONIGHT...
TEMPERATURES THROUGH THE PERIOD AND RAIN CHANCES FOR THANKSGIVING
DAY.
ALREADY GETTING REPORTS OF VSBYS NEAR ZERO IN FOG BETWEEN 23Z-00Z
LATE THIS AFTERNOON...AS MOISTURE/BR/LOW CLOUDS FROM TODAY PERSIST
ACROSS PORTIONS OF THE AREA. LIGHT WINDS...CLEAR/MOSTLY CLEAR SKIES
AND RADIATIONAL COOLING WILL ONLY ALLOW THE FOG TO BECOME MORE
WIDESPREAD AND VSBYS TO CONTINUE DROPPING THRU THE EVENING HOURS.
THUS HAVE HOISTED ANOTHER DENSE FOG ADVISORY FOR TONIGHT INTO
WEDNESDAY MORNING...STARTING AT 00Z IN THE AREAS WHERE THE FOG/LOW
CLOUDS PERSISTED TODAY. STARTED ADVISORY IN PORTIONS OF CENTRAL
WISCONSIN...WHERE SUNNY SKIES ALLOWED FOR PLENTY OF WARMING/MIXING
OF THE BOUNDARY LAYER TODAY...AT 03Z.
LEFT ANY FOG ADVISORY OUT OF THE NORTH END OF THE FCST AREA...WHERE
CIRRUS CLOUDS WILL SPREAD OVER DURING THE MID EVENING HOURS AND
LIMIT RADIATIONAL COOLING. LEFT FOG ADVISORY OUT OF THE HIGHER
ELEVATION PORTIONS OF NORTHEAST IA/SOUTHEAST MN...WHERE GRADIENT
WINDS EXPECTED TO INCREASE INTO THE 8-15KT RANGE AROUND MIDNIGHT AND
AFTER. THIS INCREASED BOUNDARY LAYER MIXING LATER TONIGHT SHOULD
LIMIT THE DENSE FOG POTENTIAL IN THOSE AREAS.
.LONG TERM...
301 PM CST TUE NOV 20 2012
MEDIUM RANGE MODELS DO SHOW SOME DIFFERENCES IN THIS TIME FRAME.
20.12Z ECMWF HAS BACKED OFF ON A NEGATIVELY TILTED TROUGH DEVELOPING
EARLY NEXT WEEK AND NOW HAS MAINLY A ZONAL FLOW REGIME. GFS AND
ECMWF DO DIFFER WITH SOME SUBTLE WAVES EXPECTED TO TRANSLATE THROUGH
THE FLOW FROM SUNDAY THROUGH TUESDAY. SURFACE HIGH PRESSURE WILL
DOMINATE THE PATTERN SATURDAY...BUT AFTER THAT CONFIDENCE IS RATHER
LOW IN ANY ONE SOLUTION AND THUS HAVE WENT WITH THE MODEL CONSENSUS.
TEMPERATURES LOOK TO REMAIN BELOW NORMAL THROUGH THE PERIOD...WITH
HIGHS MAINLY IN THE 30S WITH LOWS IN THE TEENS AND 20S.
&&
.AVIATION...THROUGH 06Z THURSDAY
1136 PM CST TUE NOV 20 2012
LATEST RAP CONTINUES TO SHOW THAT THE LOW LEVEL MOISTURE REMAINS
TRAPPED BELOW THE SUBSIDENCE INVERSION AT KLSE THROUGH MOST OF THE
MORNING...AND THEN THIS MOISTURE MIXES OUT QUICKLY AS THE GRADIENT
INCREASES. DUE TO THIS...EXTENDED THE LIFR CEILINGS AND
VISIBILITIES FROM 21.07Z TO 21.17Z. IN THE HIGHER ELEVATIONS
ALONG THE MISSISSIPPI AND WISCONSIN...AND IN CENTRAL WISCONSIN
EXPECT THAT THE DENSE FOG WILL DISSIPATE QUICKLY BETWEEN 21.16Z
AND 21.18Z. ONCE THE INVERSION BREAKS EXPECT VFR CEILINGS AND
VISIBILITIES FOR THE REMAINDER OF THIS TIME PERIOD.
ORIGINALLY THOUGHT THAT THE LOW CEILINGS AND VISIBILITIES MAY GET
INTO KRST...BUT WITH THE DENSE CIRRUS NOW OVERHEAD AND WINDS
NEAR 10 KNOTS EXPECT THAT THE RADIATIVE COOLING MAY HAVE SLOWED
ENOUGH TO PREVENT THIS FROM OCCURRING. WITH THIS SAID...THE
VISIBILITIES WILL LIKELY BECOME MVFR DUE TO HAZE BETWEEN 21.09Z
AND 21.17Z. OTHERWISE...BOTH THE CEILINGS AND VISIBILITIES SHOULD
BE VFR THROUGH THE REMAINDER OF THE PERIOD.
&&
.CLIMATE...
200 AM CST SUN NOV 18 2012
RECORD HIGH TEMPERATURES FOR WEDNESDAY/21ST AND THURSDAY/22ND. COOP
SITES ARE 7 AM-7 AM HIGHS...THUS 22ND HIGHS ARE 21.12Z TO 22.12Z.
LA CROSSE AND ROCHESTER ARE THE ONLY NON-COOP SITES.
FORECAST HIGH TEMPERATURES SUGGEST SOME OF THE RECORDS BELOW MAY
BE TIED OR BROKEN.
LOCATION WEDNESDAY/21ST THURSDAY/22ND
LA CROSSE WI 72/1990 59/1963
SPARTA WI 65/1990 70/1990
MEDFORD WI 59/1913 65/1990
LANCASTER WI 66/2003 66/1898
MAUSTON WI 67/2003 66/1990
ROCHESTER MN 69/1990 65/1913
AUSTIN MN 70/1990 58/1966
WINONA DAM 5A MN 60/2003 60/2001
WABASHA MN 61/1908 59/1908
CHARLES CITY IA 71/1990 62/1966
OELWEIN IA 71/1990 62/1966
DECORAH IA 71/1990 62/1908
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
601 PM CST TUE NOV 20 2012
WI...DENSE FOG ADVISORY UNTIL 10 AM CST WEDNESDAY FOR WIZ032-033-
041-053>055-061.
DENSE FOG ADVISORY FROM 9 PM THIS EVENING TO 10 AM CST
WEDNESDAY FOR WIZ034-042>044.
MN...DENSE FOG ADVISORY UNTIL 10 AM CST WEDNESDAY FOR MNZ079-088-
096.
IA...DENSE FOG ADVISORY UNTIL 10 AM CST WEDNESDAY FOR IAZ010-011-
029-030.
&&
$$
SHORT TERM...RABERDING/RRS
LONG TERM....RABERDING
AVIATION...BOYNE
CLIMATE......JONES/DB/AJ/BOYNE
AREA FORECAST DISCUSSION
NWS NEW YORK NY
935 AM EST WED NOV 21 2012
.SYNOPSIS...
HIGH PRESSURE ALONG THE EASTERN SEABOARD WILL REMAIN IN CONTROL OF
OUR WEATHER INTO FRIDAY. A COLD FRONT WILL MOVE ACROSS THE AREA
LATE FRIDAY NIGHT FOLLOWED BY HIGH PRESSURE BUILDING IN FROM THE
WEST THIS WEEKEND INTO EARLY NEXT WEEK. A COMPLEX STORM SYSTEM
APPROACHES THE AREA ON TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MINOR ADJUSTMENTS MADE THIS MORNING TO ACCOUNT FOR LATEST OBS.
FORECAST REMAINS ON TRACK.
CIRRUS FROM UPPER SHORTWAVE IS PROGRESSING EAST. HAVE FOLLOWED
LATEST RAP TIME-LAGGED ENSEMBLE FOR CLOUD GRIDS WHICH IS VERY
CLOSE TO OBSERVED TREND. THIS RESULTS IN A SUNNY OR BECOMING SUNNY
NORTH AND EAST FCST.
TEMPS TODAY ARE CLOSE TO GFS MOS. WHILE MAVS HAVE BEEN TOO WARM OF
LATE AND BIAS CORRECTED GRIDDED GFS MOS IS 3 DEGREES
COOLER...BELIEVE NEARLY FULL SUN WILL ALLOW THE 50 TO 55 FCST TO
VERIFY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
HIGH PRESSURE PERSISTS. THUS...CONTINUED WITH A PERSISTENCE FCST.
STRATUS DECK FROM GULF OF MAINE CLIPS SE CT AND LONG ISLAND
OVERNIGHT AS SEEN IN GFS LOW LEVEL RH FIELDS.
THANKSGIVING FINDS LIGHT NE WINDS AND MOSTLY SUNNY SKIES - A FINE
DAY FOR A PARADE...TRAVEL AND GIVING THANKS.
TEMPS ARE FCST JUST A TAD ABOVE NORMAL AND CLOSE TO GFS MOS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE NAM IS A FAST OUTLIER WITH THE COLD FRONT FRIDAY AND FRIDAY
NIGHT...SO DISCARDED ITS GENERAL SOLUTION. USED A GFS/ECMWF/CMC-
GLOBAL BLEND THURSDAY NIGHT-MONDAY. THE GFS QUITE LIKELY...GIVEN
ITS KNOWN BIAS TO ERODE HIGHS OVER THE CANADIAN MARITIMES/NORTH
ATLANTIC TO QUICKLY...A BIT FAR N/W AND TOO FAST WITH THE SYSTEM
APPROACHING BY TUESDAY...SO LEANED TOWARDS TO THE ECMWF THERE
AFTER...NOTING SUPPORT FROM THE CMC-GLOBAL THROUGH 144 HOURS.
A DEEP LAYERED RIDGE CROSSES THE AREA THURSDAY NIGHT...GIVING WAY
TO AN APPROACHING FULL LATITUDE TROUGH FRIDAY AND FRIDAY NIGHT. THIS
TROUGH THEN CROSSES THE AREA SATURDAY AND SATURDAY NIGHT.
IN TERMS OF SENSIBLE WEATHER...THURSDAY NIGHT SHOULD BE DRY DUE TO
SUBSIDENCE UNDER THE RIDGE. HAVE SLIGHT CHANCE POPS IN FAR WESTERN
ZONES FRIDAY (CHANCE FAR W ORANGE) FRIDAY AFTERNOON...THEN CHANCE
POPS FOR ALL BUT FAR SW ZONES FRIDAY NIGHT WITH THE PASSAGE OF THE
SURFACE COLD FRONT. ALL GUIDANCE SUGGESTS THAT PRECIPITATION COULD
HAVE TROUBLE GETTING INTO NYC METRO FRIDAY NIGHT...SO ONLY SLIGHT
CHANCE POPS THERE. SLIGHT CHANCE POPS WEST/CHANCE POPS EVERYWHERE
SATURDAY DUE TO INSTABILITY AND LINGERING POST-FRONTAL SHOWERS.
APPEARS SHOULD HAVE ENOUGH LOW LEVEL COLD AIR WORK IN LATE FRIDAY
NIGHT THAT NW ZONES COULD SEE A -SHRA/-SHSN MIX AND POSSIBLE
CHANGE TO ALL SNOW SHOWERS SATURDAY MORNING. EXPECT SUFFICIENT
BOUNDARY LAYER WARMING THAT SHOULD SEE ONLY -SHRA IN THE
AFTERNOON. EXPECT GUSTY NW WINDS IN RESPONSE TO STRONG LOW LEVEL
COLD ADVECTION SATURDAY. SHOULD SEE SUFFICIENT DRYING BY SATURDAY
NIGHT WITH CONTINUING GUSTY NW WINDS TO GO WITH A DRY FORECAST
THEN.
NW FLOW ALOFT SUNDAY AND SUNDAY NIGHT GIVES WAY TO RIDGING
BUILDING IN MONDAY...WITH DRY CONDITIONS ACROSS THE REGION.
THE RIDGE SLIDES TO THE EAST MONDAY NIGHT. SW FLOW ALOFT ON
TUESDAY AHEAD OF A FULL LATITUDE TROUGH BUILDING INTO THE GREAT
LAKES AND MID- SOUTH. A SURFACE LOW SHOULD TRACK TO THE EASTERN
GREAT LAKES BY TUESDAY NIGHT. WITH ITS ASSOCIATED WARM FRONT
LIKELY STAYING TO OUR S MONDAY NIGHT AND TUESDAY...WENT WITH
STRATIFORM PRECIPITATION IN RESPONSE TO OVER RUNNING WITH SLIGHT
CHANCE POPS MONDAY NIGHT AND CHANCE POPS TUESDAY. FOR NOW HAVE A
WINTRY MIX CHANGING TO RAIN ACROSS NORTHERN INTERIOR ZONES...AND
JUST RAIN OVER SOUTHERN ZONES MONDAY NIGHT AND TUESDAY.
FOR TEMPERATURES THURSDAY NIGHT AND FRIDAY...USED A BLEND OF MAV/MET
GUIDANCE...MIXING IN NAM 2-METER TEMPERATURES AND MIXING DOWN FROM
950 HPA FOR HIGHS TUESDAY...WITH TEMPERATURES SLIGHTLY ABOVE
NORMAL IN BOTH PERIODS.
FROM FRIDAY NIGHT THROUGH TUESDAY USED A BLEND OF MEX/MEX ENSEMBLE
MEAN/HPC GUIDANCE...WEIGHING MORE AND MORE TOWARDS ECE GUIDANCE
TOWARDS THE END OF THE PERIOD. EXCEPT FOR NEAR NORMAL LOWS FRIDAY
NIGHT...EXPECT BELOW NORMAL TEMPERATURES IN THIS TIME FRAME.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
HIGH PRES WILL MOVE SLOWLY SOUTHEAST ACROSS THE AREA THROUGH THANKSGIVING
DAY.
WIND FORECAST TODAY...NE WIND SPEEDS WERE INCREASED BY A FEW KTS
TO 10-12 KT.
VFR WEATHER IS FORECAST THROUGH SUNSET. THERE IS A LOW POTENTIAL FOR
CIGS AROUND 3K FT TO DEVELOP KISP-KGON AFT 16-18Z. MVFR STRATUS LIKELY
TO DEVELOP TNGT. THIS SHOULD OVERSPREAD THE AREA FROM THE E. MVFR HAS
BEEN INCLUDED IN THE TAFS. POTENTIAL EXISTS FOR THIS STRATUS TO REMAIN
OFFSHORE...BUT THE PROB IS HIGHER THAT IT WILL IMPACT THE AREA TERMINALS
ATTM.
BAND OF MVFR EXPECTED TO ERODE DURING THE DAY ON THU...WITH VFR BY
AFTN.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KJFK FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KLGA FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
.OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...
.THURSDAY...MVFR IN THE MRNG. VFR IN THE AFTN. NE FLOW AROUND 10KT.
.THURSDAY NIGHT-FRIDAY...VFR.
.FRIDAY NIGHT...COLD FROPA...ACCOMPANIED BY SCT RAIN SHOWERS WITH
POSSIBLE BRIEF MVFR CONDS. NW WINDS G25-30KT BEHIND FROPA.
.SATURDAY...SOME SNOW FLURRIES POSSIBLE NW OF CITY TERMINALS. NW
WINDS G25-30KT.
.SUNDAY...GUSTY NW WINDS G15-20KT.
&&
.MARINE...
FORECAST REMAINS ON TRACK.
PERSISTENT NE FLOW CONTINUES THROUGH EARLY FRIDAY BETWEEN INLAND
HIGH PRESSURE AND A DISTANT OCEAN LOW. WINDS REMAIN BELOW SCA
LEVELS...BUT OCEAN SEAS WILL REMAIN IN THE 5-7 FT RANGE VIA SE
SWELL FROM THE OFFSHORE LOW.
SEAS WILL REMAIN RATHER ROUGH ON THE OCEAN WATERS THURSDAY INTO
FRIDAY DUE TO EASTERLY SWELL.
LINGERING SE SWELLS SHOULD KEEP SEAS AT SCA LEVEL FRIDAY
NIGHT...WITH SUB-SCA CONDITIONS ELSEWHERE. GALE FORCE GUSTS LIKELY
ON ALL WATERS SATURDAY...DUE TO STRONG LOW LEVEL COLD ADVECTION.
THESE GUSTS COULD LINGER INTO EARLY SUNDAY. AT LEAST SCA
CONDITIONS EXPECTED ON SUNDAY.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION EXPECTED THROUGH MONDAY.
&&
.EQUIPMENT...
THE KOKX WSR-88D IS OUT OF SERVICE DUE TO A MAJOR NON STORM
RELATED MECHANICAL FAILURE. THE RADAR IS EXPECTED TO RETURN TO
SERVICE BY THE FIRST WEEK OF DECEMBER.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 AM EST FRIDAY
FOR ANZ350-353-355.
&&
$$
SYNOPSIS...MALOIT/TONGUE
NEAR TERM...MALOIT/TONGUE
SHORT TERM...TONGUE
LONG TERM...MALOIT
AVIATION...GC
MARINE...MALOIT/TONGUE
HYDROLOGY...MALOIT/TONGUE
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
622 AM EST WED NOV 21 2012
.SYNOPSIS...
HIGH PRESSURE ALONG THE EASTERN SEABOARD WILL REMAIN IN CONTROL OF
OUR WEATHER INTO FRIDAY. A COLD FRONT WILL MOVE ACROSS THE AREA
LATE FRIDAY NIGHT FOLLOWED BY HIGH PRESSURE BUILDING IN FROM THE
WEST THIS WEEKEND INTO EARLY NEXT WEEK. A COMPLEX STORM SYSTEM
APPROACHES THE AREA ON TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MINOR UPDATES TO THE GRIDS TO REFLECT THE LATEST TRENDS IN
OBSERVATIONS AND GUIDANCE. FORECAST APPEARS ON TRACK.
CIRRUS FROM UPPER SHORTWAVE IS PROGRESSING EAST. HAVE FOLLOWED
LATEST RAP TIME-LAGGED ENSEMBLE FOR CLOUD GRIDS WHICH IS VERY
CLOSE TO OBSERVED TREND. THIS RESULTS IN A SUNNY OR BECOMING SUNNY
NORTH AND EAST FCST.
TEMPS TODAY ARE CLOSE TO GFS MOS. WHILE MAVS HAVE BEEN TOO WARM OF
LATE AND BIAS CORRECTED GRIDDED GFS MOS IS 3 DEGREES
COOLER...BELIEVE NEARLY FULL SUN WILL ALLOW THE 50 TO 55 FCST TO
VERIFY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
HIGH PRESSURE PERSISTS. THUS...CONTINUED WITH A PERSISTENCE FCST.
STRATUS DECK FROM GULF OF MAINE CLIPS SE CT AND LONG ISLAND
OVERNIGHT AS SEEN IN GFS LOW LEVEL RH FIELDS.
THANKSGIVING FINDS LIGHT NE WINDS AND MOSTLY SUNNY SKIES - A FINE
DAY FOR A PARADE...TRAVEL AND GIVING THANKS.
TEMPS ARE FCST JUST A TAD ABOVE NORMAL AND CLOSE TO GFS MOS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE NAM IS A FAST OUTLIER WITH THE COLD FRONT FRIDAY AND FRIDAY
NIGHT...SO DISCARDED ITS GENERAL SOLUTION. USED A GFS/ECMWF/CMC-
GLOBAL BLEND THURSDAY NIGHT-MONDAY. THE GFS QUITE LIKELY...GIVEN
ITS KNOWN BIAS TO ERODE HIGHS OVER THE CANADIAN MARITIMES/NORTH
ATLANTIC TO QUICKLY...A BIT FAR N/W AND TOO FAST WITH THE SYSTEM
APPROACHING BY TUESDAY...SO LEANED TOWARDS TO THE ECMWF THERE
AFTER...NOTING SUPPORT FROM THE CMC-GLOBAL THROUGH 144 HOURS.
A DEEP LAYERED RIDGE CROSSES THE AREA THURSDAY NIGHT...GIVING WAY
TO AN APPROACHING FULL LATITUDE TROUGH FRIDAY AND FRIDAY NIGHT. THIS
TROUGH THEN CROSSES THE AREA SATURDAY AND SATURDAY NIGHT.
IN TERMS OF SENSIBLE WEATHER...THURSDAY NIGHT SHOULD BE DRY DUE TO
SUBSIDENCE UNDER THE RIDGE. HAVE SLIGHT CHANCE POPS IN FAR WESTERN
ZONES FRIDAY (CHANCE FAR W ORANGE) FRIDAY AFTERNOON...THEN CHANCE
POPS FOR ALL BUT FAR SW ZONES FRIDAY NIGHT WITH THE PASSAGE OF THE
SURFACE COLD FRONT. ALL GUIDANCE SUGGESTS THAT PRECIPITATION COULD
HAVE TROUBLE GETTING INTO NYC METRO FRIDAY NIGHT...SO ONLY SLIGHT
CHANCE POPS THERE. SLIGHT CHANCE POPS WEST/CHANCE POPS EVERYWHERE
SATURDAY DUE TO INSTABILITY AND LINGERING POST-FRONTAL SHOWERS.
APPEARS SHOULD HAVE ENOUGH LOW LEVEL COLD AIR WORK IN LATE FRIDAY
NIGHT THAT NW ZONES COULD SEE A -SHRA/-SHSN MIX AND POSSIBLE
CHANGE TO ALL SNOW SHOWERS SATURDAY MORNING. EXPECT SUFFICIENT
BOUNDARY LAYER WARMING THAT SHOULD SEE ONLY -SHRA IN THE
AFTERNOON. EXPECT GUSTY NW WINDS IN RESPONSE TO STRONG LOW LEVEL
COLD ADVECTION SATURDAY. SHOULD SEE SUFFICIENT DRYING BY SATURDAY
NIGHT WITH CONTINUING GUSTY NW WINDS TO GO WITH A DRY FORECAST
THEN.
NW FLOW ALOFT SUNDAY AND SUNDAY NIGHT GIVES WAY TO RIDGING
BUILDING IN MONDAY...WITH DRY CONDITIONS ACROSS THE REGION.
THE RIDGE SLIDES TO THE EAST MONDAY NIGHT. SW FLOW ALOFT ON
TUESDAY AHEAD OF A FULL LATITUDE TROUGH BUILDING INTO THE GREAT
LAKES AND MID- SOUTH. A SURFACE LOW SHOULD TRACK TO THE EASTERN
GREAT LAKES BY TUESDAY NIGHT. WITH ITS ASSOCIATED WARM FRONT
LIKELY STAYING TO OUR S MONDAY NIGHT AND TUESDAY...WENT WITH
STRATIFORM PRECIPITATION IN RESPONSE TO OVER RUNNING WITH SLIGHT
CHANCE POPS MONDAY NIGHT AND CHANCE POPS TUESDAY. FOR NOW HAVE A
WINTRY MIX CHANGING TO RAIN ACROSS NORTHERN INTERIOR ZONES...AND
JUST RAIN OVER SOUTHERN ZONES MONDAY NIGHT AND TUESDAY.
FOR TEMPERATURES THURSDAY NIGHT AND FRIDAY...USED A BLEND OF MAV/MET
GUIDANCE...MIXING IN NAM 2-METER TEMPERATURES AND MIXING DOWN FROM
950 HPA FOR HIGHS TUESDAY...WITH TEMPERATURES SLIGHTLY ABOVE
NORMAL IN BOTH PERIODS.
FROM FRIDAY NIGHT THROUGH TUESDAY USED A BLEND OF MEX/MEX ENSEMBLE
MEAN/HPC GUIDANCE...WEIGHING MORE AND MORE TOWARDS ECE GUIDANCE
TOWARDS THE END OF THE PERIOD. EXCEPT FOR NEAR NORMAL LOWS FRIDAY
NIGHT...EXPECT BELOW NORMAL TEMPERATURES IN THIS TIME FRAME.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
HIGH PRES WILL BUILD SWD OVER THE REGION THRU THANKSGIVING.
LGT NE WINDS THRU THE TAF PERIOD. SPEEDS AROUND 10KT DURING THE
DAYTIME HRS.
MAINLY VFR TODAY WITH MID AND HIGH CLOUDS. LOW POTENTIAL FOR CIGS
AROUND 3K FT TO DEVELOP KISP-KGON AFT 16-18Z. MVFR STRATUS LIKELY TO
DEVELOP TNGT. THIS SHOULD OVERSPREAD THE AREA FROM THE E. MVFR HAS
BEEN INCLUDED IN THE TAFS. POTENTIAL EXISTS FOR THIS STRATUS TO
REMAIN OFFSHORE...BUT THE PROB IS HIGHER THAT IT WILL IMPACT THE
AREA TERMINALS ATTM.
BAND OF MVFR EXPECTED TO ERODE DURING THE DAY ON THU...WITH VFR BY
AFTN.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KJFK FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KLGA FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
.OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...
.THURSDAY...MVFR IN THE MRNG. VFR IN THE AFTN. NE FLOW AROUND 10KT.
.THURSDAY NIGHT-FRIDAY...VFR.
.FRIDAY NIGHT...COLD FROPA...ACCOMPANIED BY SCT SHOWERS WITH
POSSIBLE BRIEF MVFR CONDS. NW WINDS G25-30KT BEHIND FROPA.
.SATURDAY...SOME SNOW FLURRIES POSSIBLE NW OF CITY TERMINALS. NW
WINDS G25-30KT.
.SUNDAY...GUSTY NW WINDS G15-20KT.
&&
.MARINE...
MINOR CHANGES TO THE GRIDS TO REFLECT THE LATEST TRENDS IN
OBSERVATIONS AND GUIDANCE. FORECAST APPEARS ON TRACK.
PERSISTENT NE FLOW CONTINUES THROUGH EARLY FRIDAY BETWEEN INLAND
HIGH PRESSURE AND A DISTANT OCEAN LOW. WINDS REMAIN BELOW SCA
LEVELS...BUT OCEAN SEAS WILL REMAIN IN THE 5-7 FT RANGE VIA SE
SWELL FROM THE OFFSHORE LOW.
SEAS WILL REMAIN RATHER ROUGH ON THE OCEAN WATERS THURSDAY INTO
FRIDAY DUE TO EASTERLY SWELL.
LINGERING SE SWELLS SHOULD KEEP SEAS AT SCA LEVEL FRIDAY
NIGHT...WITH SUB-SCA CONDITIONS ELSEWHERE. GALE FORCE GUSTS LIKELY
ON ALL WATERS SATURDAY...DUE TO STRONG LOW LEVEL COLD ADVECTION.
THESE GUSTS COULD LINGER INTO EARLY SUNDAY. AT LEAST SCA
CONDITIONS EXPECTED ON SUNDAY.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION EXPECTED THROUGH MONDAY.
&&
.EQUIPMENT...
THE KOKX WSR-88D IS OUT OF SERVICE DUE TO A MAJOR NON STORM
RELATED MECHANICAL FAILURE. THE RADAR IS EXPECTED TO RETURN TO
SERVICE BY THE FIRST WEEK OF DECEMBER.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 AM EST FRIDAY
FOR ANZ350-353-355.
&&
$$
SYNOPSIS...TONGUE/MALOIT
NEAR TERM...MALOIT/TONGUE
SHORT TERM...TONGUE
LONG TERM...MALOIT
AVIATION...12
MARINE...MALOIT/TONGUE
HYDROLOGY...TONGUE/MALOIT
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
929 AM EST WED NOV 21 2012
.UPDATE...
AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 302 AM EST WED NOV 21 2012
HIGH PRESSURE WILL REMAIN IN CONTROL UNTIL THURSDAY NIGHT...WHEN A
COLD FRONT IS EXPECTED TO PASS THROUGH THE AREA. IN THE WAKE OF
FRONT...HIGH PRESSURE WILL BUILD IN FOR THE WEEKEND. A LOW PRESSURE
SYSTEM MAY MOVE INTO THE AREA EARLY NEXT WEEK.
&&
.NEAR TERM /TODAY/...
ISSUED AT 754 AM EST WED NOV 21 2012
HAVE EXPANDED THE DENSE FOG ADVISORY IN AREAL COVERAGE AND IN TIME
BASED ON RECENT SATELLITE TRENDS...OBS AND AREA WEBCAMS. THE MORE
WIDESPREAD FOG HAS EXPANDED INTO THE NORTHERN INDY METRO AND SHOULD
CONTINUE TO ADVANCE SOUTHEAST OVER THE NEXT HOUR OR TWO. RAP 975MB
RH PROGS SUGGEST THAT WIDESPREAD FOG SHOULD EXPAND SOUTH THROUGH THE
ENTIRE WABASH VALLEY TO VINCENNES AND ACROSS THE ENTIRE INDY METRO.
PERSISTENT DRY EASTERLY FLOW IN THE NEAR SURFACE LEVEL SHOULD KEEP
MORE WIDESPREAD FOG OUT OF THE SOUTHEAST COUNTIES BUT WILL NEED TO
MONITOR THROUGH THE MORNING.
ALSO EXTENDED THE ADVISORY OUT THROUGH 18Z WITH THE RIDGE AXIS ALOFT
NOT EXPECTED TO ARRIVE ACROSS THE REGION UNTIL THIS AFTERNOON. WIND
FLOW THROUGHOUT THE LOW LEVELS REMAINS LIGHT...AND POTENTIAL
CERTAINLY EXISTS THAT ADVISORY MAY NEED TO BE EXTENDED OUT EVEN
FURTHER IN TIME BASED ON COVERAGE AND EXTENT OF DENSE FOG BY MIDDAY.
ON TUESDAY...WIDESPREAD FOG/STRATUS THAT DEVELOPED ON THE LEE
SIDE OF THE UPPER RIDGE AXIS ACROSS EASTERN IOWA AND EXTREME WESTERN
ILLINOIS TOOK INTO THE MID AFTERNOON TO BREAK FOR MUCH OF THE AREA.
ZONE AND GRID UPDATES OUT. PREVIOUS DISCUSSION FOLLOWS.
IMMEDIATE CONCERN THIS MORNING WILL BE THE FOG. SATELLITE LOOPS
AND SURFACE OBSERVATIONS INDICATE AN AREA OF DENSE FOG OVER
NORTHEAST ILLINOIS AND NORTHWEST INDIANA HAS BEEN DRIFTING SOUTH
OVER THE PAST COUPLE OF HOURS. LEADING EDGE IS MOVING INTO THE FAR
NORTHWEST ZONES. PLANNING ON A DENSE FOG ADVISORY FOR SOME OF THE
NORTHWEST ZONES INTO THE LATE MORNING HOURS. UNCLEAR EXACTLY HOW FAR
SOUTH FOG BANK WILL GET THIS MORNING DUE TO SOME LINGERING CLOUD
COVER...BUT MAY NEED TO EXPAND IT FARTHER SOUTH IF CONDITIONS
WARRANT LATER THIS MORNING.
MODEL DATA SUGGEST NOCTURNAL INVERSION WILL BEGIN TO BREAK AFTER
211500Z...SO EXPECTING THE FOG TO BEGIN DISSIPATING BY THE LATE
MORNING HOURS. MIXING APPEARS LIMITED TODAY...SO IF THE FOG BECOMES
MORE WIDESPREAD THAN CURRENTLY THINKING...IT MAY LINGER LONGER INTO
THE DAY.
OTHERWISE...DRY WEATHER EXPECTED TODAY WITH HIGH PRESSURE IN
CONTROL. PROGGED LOW LEVEL THICKNESSES GENERALLY SUPPORT THE GFS MOS
HIGHS FOR TODAY. IF THE FOG HOLDS ON LONGER INTO THE DAY...THE HIGHS
WILL BE TOO WARM.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY/...
ISSUED AT 302 AM EST WED NOV 21 2012
MODELS INDICATE THE MAIN ITEM OF INTEREST DURING THIS PERIOD WILL BE
THE UPPER TROUGH CURRENTLY MOVING INTO THE PACIFIC NORTHWEST. THIS
TROUGH IS EXPECTED TO MOVE EAST...PASSING THOUGH THE GREAT LAKES
AROUND FRIDAY. AN ASSOCIATED COLD FRONT IS EXPECTED TO MOVE THROUGH
THE LOCAL AREA THURSDAY NIGHT. APPEARS THERE IS A DECENT AMOUNT OF
LIFT ASSOCIATED WITH THE FRONT...HOWEVER MODELS SUGGEST THERE MAY BE
ONLY A RELATIVELY NARROW AREA OF NEAR SATURATION IN THE
PRECIPITATION BEARING LAYERS. BASED ON THE ABOVE...WILL KEEP POPS IN
THE CHANCE CATEGORY FOR NOW WITH RESPECT TO THIS EVENT. WILL GO WITH
SMALL CHANCE POPS OVER THE FAR NORTHWEST FOR LATE IN THE DAY
THURSDAY...AND CHANCE POPS ALL AREAS THURSDAY NIGHT.
MODELS SUGGEST THE LIFT/DEEPER MOISTURE WILL BE WELL OFF THE
SOUTHEAST BY SUNRISE FRIDAY...SO WILL TAKE OUT THE POPS FOR FRIDAY.
PROGGED LOW LEVEL THICKNESSES GENERALLY SUPPORT THE GFS MOS THROUGH
THE PERIOD...SO WILL NOT STRAY TOO FAR FROM THEM. ONLY EXCEPTION
WILL BE THE THURSDAY NIGHT LOWS. GIVEN THE STRONG COLD
ADVECTION...DECIDED TO TRIM A FEW DEGREES OFF OF THE GUIDANCE
LOWS...ESPECIALLY IN THE NORTHWEST.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
ISSUED AT 330 AM EST WED NOV 21 2012
TEMPERATURES WILL BE QUITE COLD THIS WEEKEND...ESPECIALLY SATURDAY
AS A STRONG UPPER TROUGH OVER THE EASTERN GREAT LAKES MOVES
EASTWARD. HIGH PRESSURE OVER THE PLAINS AND MID MISSISSIPPI VALLEY
WILL MOVE EAST ACROSS OUR REGION OVER THE WEEKEND BRINGING DRY
WEATHER AND A SLIGHT MODERATION IN TEMPERATURES SUNDAY.
MODELS DIG ANOTHER UPPER TROUGH INTO THE NORTHERN PLAINS MONDAY AND
MOVE IT INTO THE GREAT LAKES TUESDAY. THEY ALSO DEVELOP A SURFACE
LOW OVER THE SOUTH CENTRAL PLAINS MONDAY AND TRACK IT ACROSS OUR
REGION TUESDAY.
MODELS THIS RUN HAVE TRENDED WARMER AND WILL ADJUST ADJUST
TEMPERATURES UP A LITTLE AND MOVE THE RAIN SNOW LINE NORTH AS WELL
MONDAY AND MONDAY NIGHT. AFTER THE LOW TRACKS BY EARLY
TUESDAY...THERE COULD BE FALLING TEMPERATURES LATER TUESDAY...BUT IT
IS TOO FAR OUT TO MENTION THAT AT THIS TIME.
ACCEPTED ALL BLEND TEMPERATURES AND POPS MOST PERIODS. ADDED A
LITTLE MORE GRADIENT IN TEMPERATURES MONDAY AND TUESDAY AS THERE
WILL BE A STRONG FRONT ACROSS OUR REGION.
&&
.AVIATION /DISCUSSION FOR 15Z TAF UPDATE/...
ISSUED AT 929 AM EST WED NOV 21 2012
FOG AND LOWER VISIBILITIES CONTINUE TO IMPACT ALL TERMINALS AT
14Z...WITH GREATEST IMPACTS AT KHUF AND KLAF. ADJUSTED TIMING JUST A
BIT ON IMPROVEMENT OF VISIBILITIES...BUT OVERALL DO NOT EXPECT A
RETURN TO VFR CONDITIONS UNTIL 18Z OR BEYOND.
12Z DISCUSSION FOLLOWS.
SATELLITE INDICATES AREA OF FOG ACROSS ILLINOIS AND NORTHWEST
INDIANA HAS BEEN EXPANDING SOUTHEAST INTO CENTRAL INDIANA. EXPECT
CONDITIONS TO WORSEN THROUGH ABOUT 14-15Z ESPECIALLY AREAS NORTH AND
WEST OF KIND. KHUF AND KLAF WILL BE PREDOMINATELY LIFR WHILE KBMG
AND KIND LIFR OR IFR THROUGH ABOUT 16Z. AFTER THAT THERE SHOULD BE
SOME IMPROVEMENT WITH DAYTIME HEATING. KLAF MORE IN THE FOG AREA MAY
BREAK OUT LATER.
WILL GRADUALLY IMPROVE TAFS TO VFR BY MID AFTERNOON. HIGH PRESSURE
CURRENTLY ACROSS THE AREA WILL MOVE TO THE EAST. WINDS WILL BE
LIGHT THIS AFTERNOON AND BECOMING SOUTHERLY 5 KNOTS OR LESS
TONIGHT. SOME LIGHT FOG POSSIBLE TONIGHT. BUT INCREASING SOUTHERLY
GRADIENT SHOULD LIMIT FOG OVERNIGHT. WILL KEEP TAFS MOSTLY VFR FOR
NOW AFTER FOG CLEAR THIS AFTERNOON.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
INZ021-028>031-035>049-051>055-060-061-067.
&&
$$
SYNOPSIS...JAS
NEAR TERM...JAS/RYAN
SHORT TERM...JAS
LONG TERM....JEH
AVIATION...JEH/RYAN
AREA FORECAST DISCUSSION...CORRECTED
NWS INDIANAPOLIS IN
754 AM EST WED NOV 21 2012
.UPDATE...
NEAR TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 302 AM EST WED NOV 21 2012
HIGH PRESSURE WILL REMAIN IN CONTROL UNTIL THURSDAY NIGHT...WHEN A
COLD FRONT IS EXPECTED TO PASS THROUGH THE AREA. IN THE WAKE OF
FRONT...HIGH PRESSURE WILL BUILD IN FOR THE WEEKEND. A LOW PRESSURE
SYSTEM MAY MOVE INTO THE AREA EARLY NEXT WEEK.
&&
.NEAR TERM /TODAY/...
ISSUED AT 754 AM EST WED NOV 21 2012
HAVE EXPANDED THE DENSE FOG ADVISORY IN AREAL COVERAGE AND IN TIME
BASED ON RECENT SATELLITE TRENDS...OBS AND AREA WEBCAMS. THE MORE
WIDESPREAD FOG HAS EXPANDED INTO THE NORTHERN INDY METRO AND SHOULD
CONTINUE TO ADVANCE SOUTHEAST OVER THE NEXT HOUR OR TWO. RAP 975MB
RH PROGS SUGGEST THAT WIDESPREAD FOG SHOULD EXPAND SOUTH THROUGH THE
ENTIRE WABASH VALLEY TO VINCENNES AND ACROSS THE ENTIRE INDY METRO.
PERSISTENT DRY EASTERLY FLOW IN THE NEAR SURFACE LEVEL SHOULD KEEP
MORE WIDESPREAD FOG OUT OF THE SOUTHEAST COUNTIES BUT WILL NEED TO
MONITOR THROUGH THE MORNING.
ALSO EXTENDED THE ADVISORY OUT THROUGH 18Z WITH THE RIDGE AXIS ALOFT
NOT EXPECTED TO ARRIVE ACROSS THE REGION UNTIL THIS AFTERNOON. WIND
FLOW THROUGHOUT THE LOW LEVELS REMAINS LIGHT...AND POTENTIAL
CERTAINLY EXISTS THAT ADVISORY MAY NEED TO BE EXTENDED OUT EVEN
FURTHER IN TIME BASED ON COVERAGE AND EXTENT OF DENSE FOG BY MIDDAY.
ON TUESDAY...WIDESPREAD FOG/STRATUS THAT DEVELOPED ON THE LEE
SIDE OF THE UPPER RIDGE AXIS ACROSS EASTERN IOWA AND EXTREME WESTERN
ILLINOIS TOOK INTO THE MID AFTERNOON TO BREAK FOR MUCH OF THE AREA.
ZONE AND GRID UPDATES OUT. PREVIOUS DISCUSSION FOLLOWS.
IMMEDIATE CONCERN THIS MORNING WILL BE THE FOG. SATELLITE LOOPS
AND SURFACE OBSERVATIONS INDICATE AN AREA OF DENSE FOG OVER
NORTHEAST ILLINOIS AND NORTHWEST INDIANA HAS BEEN DRIFTING SOUTH
OVER THE PAST COUPLE OF HOURS. LEADING EDGE IS MOVING INTO THE FAR
NORTHWEST ZONES. PLANNING ON A DENSE FOG ADVISORY FOR SOME OF THE
NORTHWEST ZONES INTO THE LATE MORNING HOURS. UNCLEAR EXACTLY HOW FAR
SOUTH FOG BANK WILL GET THIS MORNING DUE TO SOME LINGERING CLOUD
COVER...BUT MAY NEED TO EXPAND IT FARTHER SOUTH IF CONDITIONS
WARRANT LATER THIS MORNING.
MODEL DATA SUGGEST NOCTURNAL INVERSION WILL BEGIN TO BREAK AFTER
211500Z...SO EXPECTING THE FOG TO BEGIN DISSIPATING BY THE LATE
MORNING HOURS. MIXING APPEARS LIMITED TODAY...SO IF THE FOG BECOMES
MORE WIDESPREAD THAN CURRENTLY THINKING...IT MAY LINGER LONGER INTO
THE DAY.
OTHERWISE...DRY WEATHER EXPECTED TODAY WITH HIGH PRESSURE IN
CONTROL. PROGGED LOW LEVEL THICKNESSES GENERALLY SUPPORT THE GFS MOS
HIGHS FOR TODAY. IF THE FOG HOLDS ON LONGER INTO THE DAY...THE HIGHS
WILL BE TOO WARM.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY/...
ISSUED AT 302 AM EST WED NOV 21 2012
MODELS INDICATE THE MAIN ITEM OF INTEREST DURING THIS PERIOD WILL BE
THE UPPER TROUGH CURRENTLY MOVING INTO THE PACIFIC NORTHWEST. THIS
TROUGH IS EXPECTED TO MOVE EAST...PASSING THOUGH THE GREAT LAKES
AROUND FRIDAY. AN ASSOCIATED COLD FRONT IS EXPECTED TO MOVE THROUGH
THE LOCAL AREA THURSDAY NIGHT. APPEARS THERE IS A DECENT AMOUNT OF
LIFT ASSOCIATED WITH THE FRONT...HOWEVER MODELS SUGGEST THERE MAY BE
ONLY A RELATIVELY NARROW AREA OF NEAR SATURATION IN THE
PRECIPITATION BEARING LAYERS. BASED ON THE ABOVE...WILL KEEP POPS IN
THE CHANCE CATEGORY FOR NOW WITH RESPECT TO THIS EVENT. WILL GO WITH
SMALL CHANCE POPS OVER THE FAR NORTHWEST FOR LATE IN THE DAY
THURSDAY...AND CHANCE POPS ALL AREAS THURSDAY NIGHT.
MODELS SUGGEST THE LIFT/DEEPER MOISTURE WILL BE WELL OFF THE
SOUTHEAST BY SUNRISE FRIDAY...SO WILL TAKE OUT THE POPS FOR FRIDAY.
PROGGED LOW LEVEL THICKNESSES GENERALLY SUPPORT THE GFS MOS THROUGH
THE PERIOD...SO WILL NOT STRAY TOO FAR FROM THEM. ONLY EXCEPTION
WILL BE THE THURSDAY NIGHT LOWS. GIVEN THE STRONG COLD
ADVECTION...DECIDED TO TRIM A FEW DEGREES OFF OF THE GUIDANCE
LOWS...ESPECIALLY IN THE NORTHWEST.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
ISSUED AT 330 AM EST WED NOV 21 2012
TEMPERATURES WILL BE QUITE COLD THIS WEEKEND...ESPECIALLY SATURDAY
AS A STRONG UPPER TROUGH OVER THE EASTERN GREAT LAKES MOVES
EASTWARD. HIGH PRESSURE OVER THE PLAINS AND MID MISSISSIPPI VALLEY
WILL MOVE EAST ACROSS OUR REGION OVER THE WEEKEND BRINGING DRY
WEATHER AND A SLIGHT MODERATION IN TEMPERATURES SUNDAY.
MODELS DIG ANOTHER UPPER TROUGH INTO THE NORTHERN PLAINS MONDAY AND
MOVE IT INTO THE GREAT LAKES TUESDAY. THEY ALSO DEVELOP A SURFACE
LOW OVER THE SOUTH CENTRAL PLAINS MONDAY AND TRACK IT ACROSS OUR
REGION TUESDAY.
MODELS THIS RUN HAVE TRENDED WARMER AND WILL ADJUST ADJUST
TEMPERATURES UP A LITTLE AND MOVE THE RAIN SNOW LINE NORTH AS WELL
MONDAY AND MONDAY NIGHT. AFTER THE LOW TRACKS BY EARLY
TUESDAY...THERE COULD BE FALLING TEMPERATURES LATER TUESDAY...BUT IT
IS TOO FAR OUT TO MENTION THAT AT THIS TIME.
ACCEPTED ALL BLEND TEMPERATURES AND POPS MOST PERIODS. ADDED A
LITTLE MORE GRADIENT IN TEMPERATURES MONDAY AND TUESDAY AS THERE
WILL BE A STRONG FRONT ACROSS OUR REGION.
&&
.AVIATION /DISCUSSION FOR 12Z TAF ISSUANCE/...
ISSUED AT 600 AM EST WED NOV 21 2012
SATELLITE INDICATES AREA OF FOG ACROSS ILLINOIS AND NORTHWEST
INDIANA HAS BEEN EXPANDING SOUTHEAST INTO CENTRAL INDIANA. EXPECT
CONDITIONS TO WORSEN THROUGH ABOUT 14-15Z ESPECIALLY AREAS NORTH AND
WEST OF KIND. KHUF AND KLAF WILL BE PREDOMINATELY LIFR WHILE KBMG
AND KIND LIFR OR IFR THROUGH ABOUT 16Z. AFTER THAT THERE SHOULD BE
SOME IMPROVEMENT WITH DAYTIME HEATING. KLAF MORE IN THE FOG AREA MAY
BREAK OUT LATER.
WILL GRADUALLY IMPROVE TAFS TO VFR BY MID AFTERNOON. HIGH PRESSURE
CURRENTLY ACROSS THE AREA WILL MOVE TO THE EAST. WINDS WILL BE
LIGHT THIS AFTERNOON AND BECOMING SOUTHERLY 5 KNOTS OR LESS
TONIGHT. SOME LIGHT FOG POSSIBLE TONIGHT. BUT INCREASING SOUTHERLY
GRADIENT SHOULD LIMIT FOG OVERNIGHT. WILL KEEP TAFS MOSTLY VFR FOR
NOW AFTER FOG CLEAR THIS AFTERNOON.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
INZ021-028>031-035>049-051>055-060-061-067.
&&
$$
SYNOPSIS...JAS
NEAR TERM...JAS/RYAN
SHORT TERM...JAS
LONG TERM....JEH
AVIATION...JEH
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
616 AM EST WED NOV 21 2012
.UPDATE/AVIATION...
EWD CREEP OF DEEPER FOG REFLECTED IN LATEST SAT IMAGERY THIS MORNING
W/PRIOR UPDATE CONCENTRATING ON SLIGHT EWD EXPANSION. THIS MAY YET
NEED TO BE CARRIED FURTHER INCLUDING FORT WAYNE AREA BUT FOR NOW IS
HOLDING. OTHERWISE 09Z RUC CONTS TREND SEEN IN 06Z RUN DEPICTING
STAUNCH LL THERMAL INVERSION HOLDING FOG/STRATUS IN PLACE UNTIL
EARLY AFTN AND SIMILAR IN SCOPE TO WHAT WAS OBSVD OVR ERN IA YDA
AFTN. THUS LAMP IMPLIED TREND OF HOLDING ONTO DENSE FOG UNTIL 17-18Z
LIKELY CORRECT.
KSBN WILL HOLD AT AIRPORT MINIMUMS THROUGH AT LEAST 16Z IF NOT A BIT
LONGER ESP IN LIGHT OF WIDESPREAD UPSTREAM STRETCH OF ZERO FOG
EXTENDING ALL THE WAY BACK TO ERN IA. KFWA HOLDING IN IFR CAT BUT
CONCEDE FURTHER DETERIORATION LIKELY TWD/AFT DAYBREAK AS NOCTURNAL
COOLING MAXIMIZES AND WILL TEMPO A FURTHER REDUCTION TO LIFR VSBYS
THROUGH MID MORNING W/12Z ISSUANCE.
&&
.SHORT TERM...
DIFFICULT NR TERM PD DUE TO OVERNIGHT DVLPMNT OF WIDESPREAD
EXTREMELY DENSE FOG ACRS NW IN/SW MI WITHIN POST FNTL LK MSTR PLUME
AND RAPID CLRG ALOFT. ALTHOUGH FG LYR LOOKS THIN PER SAT OBS BELIEVE
LT NOV SUN AND WK BNDRY LYR MIXING/FLW WILL MAKE IT QUITE DIFFICULT TO
BURN OFF UNTIL LT MORNING-EARLY AFTN. THUS FEEL ITS PRUDENT TO SIGLY
UNDERCUT TEMPS IN THIS AREA.
OTHERWISE WK WAA DVLPG THROUGH AFTN AS FLW BACKS SWRLY AHD OF
IMPULSE EJECTING QUICKLY EWD OUT OF THE NEPAC. FAIRLY VIGOROUS HGT
FALLS ALOFT XPCD AS MID LVL TROF DEEPENS INTO THE WRN LAKES AND XPC
A COHESIVE AREA OF RAIN TO DVLP ALG SWWD TRAILING CDFNT THU NIGHT
AND BUMPED POPS TO HIGH CHC CWA WIDE. MUCH MORE VIGOROUS MIXING XPCD
WITHIN SHARP LL THERMAL RIDGE THU AFTN AND BUMPED TEMPS HIGHER IN
MOST AREAS.
&&
.LONG TERM...FRIDAY THROUGH TUESDAY.
STRETCH OF ABOVE NORMAL TEMPS WILL BE COMING RAPIDLY TO AN END AS
COLD AIR INFILTRATES THE REGION BEHIND A STRONG COLD FRONT WHICH
WILL HAVE CLEARED THE FORECAST AREA BY LATE FRIDAY AFTERNOON. HIGH
TEMPS WILL OCCUR EARLY IN THE DAY WITH NON-DIURNAL TREND IN TEMPS
EXPECTED WITH FALLING READINGS THROUGH THE AFTERNOON. PRECIP
ASSOCIATED WITH THE FRONT LOOK TO DEPART JUST FAST ENOUGH TO KEEP
SNOW FROM MIXING FRIDAY MORNING...BUT COULD BE A CLOSE CALL. AS COLD
AIR SETTLES ACROSS THE LAKE AND ANOTHER WAVE DROPS SE...LAKE EFFECT
POTENTIAL WILL RAMP UP WITH SFC-850 MB DELTA T STILL PROGGED FOR 20
C OR GREATER WITH INVERSION HGTS AROUND 5-6 KFT. BUFKIT SOUNDINGS
FOR NAM12 FRIDAY NIGHT INDICATE LAKE INDUCED CAPE OVER 750 J/KG.
ALLBLEND JUST NOT ABLE TO CAPTURE LAKE EFFECT POTENTIAL WELL SO HAVE
KEPT WITH PREV SHIFT ALIGNMENT AND SLGT INCREASE IN POPS. NW FLOW
OF 20 KNOTS OR SO MAY ALLOW FOR DECENT INLAND PENETRATION OF LAKE
EFFECT SHOWERS WHICH MAY WARRANT EXPANDING BEYOND WHAT IS DEPICTED.
SATURDAY LOOKS TO BE A COOL...DAMP DAY WITH HIGHS LIKELY STRUGGLING
TO MOVE THROUGH THE 30S WITH LINGERING LAKE EFFECT CLOUDS IN NE
AREAS. SKIES WILL CLEAR OUT SATURDAY NIGHT INTO SUNDAY AS UPPER
LEVEL RIDGING BUILDS INTO THE AREA. TEMPS WILL HEAD BACK CLOSER TO
NORMAL. REST OF THE FORECAST REMAINS MUDDLED WITH MODELS INDICATING
LOW PRESSURE TAKING SHAPE IN THE PANHANDLE AREA OF TX/OK AND THEN
TRACK TOWARDS THE GREAT LAKES/OHIO VALLEY BY TUESDAY. NEW ECMWF RUN
BRINGS A MORE FAVORABLE SOUTHERN TRACK TO THE SFC LOW MOVING OVER
CLEVELAND TUES AFTERNOON. THIS WOULD PLACE THE NW AREAS INTO A MORE
FAVORABLE LOCATION FOR SNOW FALL WITH COLD AIR ESTABLISHED IN THESE
AREAS. SEVERAL DAYS REMAIN TO MONITOR TRENDS BUT POPS LEFT UNTOUCHED
TOWARDS THE END WITH RAIN/SNOW MENTION CONTINUED.
&&
.AVIATION...
LT POST FNTL NW BNDRY LYR FLW AND RAPID CLRG HAD LED TO DENSE BUT
SHALLOW FG DVLPMNT ACRS NW IN/SW MI AND POSES CONSIDERABLE
UNCERTAINTY GOING FWD THROUGH LT MORNING IN TERMS OF PERVASIVENESS
AND EXTENT. GIVEN WK LL WAA ALOFT AND LIKELY POOR MIXING XPC LIFR
CONDS IN DENSE FOG TO CONT AT KSBN TERMINAL THROUGH AT LEAST MID
MORNING AND LIKELY LONGER W/GUIDANCE IMPLIED WK TO NON-EXISTENT
BNDRY LYR MIXING. DOWNSTREAM AREAS XPCD TO DUMP TO MVFR CONDS YET
LACK DEGREE OF LL MOISTENING HWVR LOW STRATUS MAY REDVLP INLINE
W/MODEL BASED RH CROSS SECTIONS AT KFWA AND WILL CONT TO MONITOR
CLOSELY THROUGH DAYBREAK.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...DENSE FOG ADVISORY UNTIL NOON EST /11 AM CST/ TODAY FOR
INZ003>008-012>017-020-022>024.
MI...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR MIZ077>080.
OH...NONE.
LM...DENSE FOG ADVISORY UNTIL 11 AM EST THIS MORNING FOR LMZ043-046.
SMALL CRAFT ADVISORY FROM 10 AM THURSDAY TO 4 PM EST SATURDAY
FOR LMZ043-046.
&&
$$
SHORT TERM...T
LONG TERM...FISHER
UPDATE/AVIATION...T
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1053 AM EST WED NOV 21 2012
.UPDATE...
ISSUED AT 1052 AM EST WED NOV 21 2012
LO CLDS ARE PROVING TO BE QUITE RESILIENT OVER THE E HALF OF THE CWA
WITH SSW FLOW OFF LK MI ENHANCING THE MOISTENING UNDER SHARP LLVL
INVRN DEPICTED ON THE 12Z GRB/APX RAOBS. TENDED TO HOLD ON TO FOG
FOR A COUPLE HRS LONGER AND LOWERED MAX TEMPS A COUPLE OF DEGREES
WHERE THE ST WL LINGER LONGEST.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 608 AM EST WED NOV 21 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL RIDGE
FROM THE SOUTHERN AND CENTRAL PLAINS INTO THE WESTERN GREAT LAKES
AND A TROUGH FROM THE GULF OF ALASKA INTO THE PACIFIC NORTHWEST. A
VIGOROUS SHORTWAVE TROUGH WAS MOVING ONSHORE INTO OR AND SOUTHERN
WA. AT THE SURFACE...SOUTHERLY FLOW WAS INCREASING BETWEEN HIGH PRES
BUILDING INTO THE EASTERN GREAT LAKES AND A TROUGH FROM NW ONTARIO
INTO EASTERN NORTH DAKOTA.
WITH ABUNDANT LOW LEVEL MOISTURE OVER THE AREA...DEWPOINTS INTO THE
MID AND UPPER 30S...AREAS OF DENSE FOG HAVE DEVELOPED OVER INTERIOR
PORTIONS OF CENTRAL UPPER MICHIGAN AND OVER THE HIGHER TERRAIN OF
THE KEWEENAW. INCREASING WINDS AND DRY ADVECTION HAS HELPED REDUCE
FOG COVERAGE/DENSITY.
TODAY...EXPECT ANY LINGERING FOG TO DISSIPATE EARLY WITH THE DRY
ADVECTION FROM THE WEST AND THE ONSET OF DAYTIME HEATING LEAVING
CLEARING SKIES. WAA WILL PUSH 850 MB TEMPERATURES ARE EXPECTED TO
REACH TO AROUND 10C...HOWEVER THE WEAK NOVEMBER SUNSHINE WILL LIMIT
TEMPERATURES TO THE MID TO UPPER 50S...WITH THE WARMER TEMPERATURES
OVER THE DOWNSLOPE LOCATIONS FAVORED BY A SOUTHERLY WIND. SOUTHERLY
WINDS WILL CONTINUE TO INCREASE OVER THE REGION AS THE PRESSURE
GRADIENT INCREASES BETWEEN LOW PRESSURE APPROACHING FROM THE
NORTHWEST AND THE HIGH TO THE SOUTHEAST.
TONIGHT...LOW PRES WILL MOVE TO NORTH OF KINL KEEPING BREEZY SOUTH
WINDS GOING. SO...LOW TEMPS WILL NOT FALL OF MUCH WITH MIN READINGS
ONLY IN THE LOWER TO MID 40S. THIS COULD AGAIN RESULT IN RECORD HIGH
LOW MINS FOR MANY LOCATIONS. THE WIND AND MIXING SHOULD ALSO
MINIMIZE POTENTIAL FOR FOG FORMATION EVEN THOUGH DEWPOINTS REMAIN
AROUND 40.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 608 AM EST WED NOV 21 2012
THANKSGIVING WILL MARK THE LAST DAY OF UNSEASONABLY WARM WEATHER FOR
AWHILE AS A SW FLOW CONTINUES TO BRING WARM AIR OVER THE GREAT LAKES
REGION AHEAD OF A FAST-APPROACHING STRONG SHORTWAVE MOVING IN FM THE
NRN PLAINS. DESPITE INCREASING WAA CLOUDS IN THE AFTERNOON AHEAD OF
THE INCOMING SHORTWAVE...MIXING TO JUST 900 MB AS INDICATED ON NAM
FCST SNDGS WOULD EASILY YIELD HIGH TEMPS IN THE MID 50S ACROSS MUCH
OF THE AREA. UPPER 50S COULD EVEN BE REACHED FOR WEST HALF LOCATIONS
ALONG LAKE SUPERIOR IN DOWNSLOPE SSW FLOW. RECORD TEMP OF 54F ON THE
22ND MAY BE IN JEOPARDY AT THE MQT NWS OFFICE. TEMPS WILL STAY A BIT
COOLER (LOW 50S) ALONG LAKE MICHIGAN SHORE IN SSW FLOW. INCREASING
MID-LVL MOISTURE AND DPVA TOWARD EVENING COULD BRING IN SOME ISOLD
SHRA LATE INTO THE WESTERN CWA SO HAVE KEPT IN SLIGHT CHC
POPS.
THURSDAY NIGHT AND FRIDAY...FOLLOWED ALONG NCEP PREFERRED BLEND OF
00Z GFS AND ECMWF WHICH ADVERTISES A SLOWER AND MORE AMPLIFIED SOLN
WITH THE NRN PLAINS SHORTWAVE AND ASSOC FRONTAL SYSTEM THAN THE NAM
OR THE CANADIAN MODELS. THE GFS AND ECMWF BLENDED SOLN ALSO HAS
SUPPORT FM THE 00Z UKMET RUN. COMPROMISE SOLN WOULD TAKE
SHORTWAVE/5H CLOSED LOW ACROSS NRN WI/CENTRAL UPR MI WITH WINDS
SHIFTING FROM WEST BEHIND INITIAL COLD FROPA IN THE EVENING TO THE
NORTHWEST OVERNIGHT BEHIND PASSAGE OF MAIN SHORTWAVE/5H TROUGH AND
SECONDARY COLD FRONT. IT IS BEHIND THIS SECONDARY COLD FRONT AND
ADVECTION OF -10 TO -12C 8H AIR OVER WRN LAKE SUPERIOR THAT LAKE
EFFECT PCPN WL QUICKLY CHANGEOVER TO SNOW LATE THU NIGHT INTO EARLY
FRIDAY. THERE COULD ALSO BE SEVERAL HOUR PERIOD OF ENHANCEMENT AS
SHORTWAVE AND ASSOC DEEP LYR Q-VECT CONV SPREADS QUICKLY ACROSS THE
AREA. ENHANCEMENT WILL BE LOST BY LATE FRI AFTERNOON AS SHORTWAVE
EXITS EAST OF THE AREA AND EVENT WILL TRANSITION TO PURE LAKE EFFECT
SNOW AS 8H TEMPS LOWER TO AROUND -15C.
FRIDAY NIGHT INTO SATURDAY...THERE MAY BE A BRIEF PERIOD FOR
ADDITIONAL ENHANCEMENT TO SNOW FRI EVENING WITH MODELS HINTING AT
ANOTHER WEAK CLIPPER SHORTWAVE MOVING ACROSS THE AREA BUT AFTER THAT
MODELS ARE IN GOOD AGREEMENT WITH STRONG RDG BUILDING IN FM NW OF
LAKE SUPERIOR. STRONG SUBSIDENCE ASSOC WITH THIS RDG WILL SHARPLY
LOWER INVERSION HGTS TO BLO 4KFT OVER THE WEST BY 12Z SAT WHICH
SHOULD QUICKLY DIMINISH LES TO FLURRIES EARLY SATURDAY. LONGER FETCH
IN NW FLOW ACROSS ERN LAKE SUPERIOR WILL ALLOW SOME LES TO
ACCUMULATE INTO SAT MORNING BUT THEN STRONG SUBSIDENCE AND DRYING
SHOULD DIMINISH ANY REMAINING LES TO FLURRIES BY AFTERNOON.
TOTAL SNOW ACCUMULATION DURING THE EVENT FM THU NIGHT INTO EARLY
SATURDAY WILL LIKELY REACH 3-7 INCHES WITH THE HIGHEST AMOUNTS OVER
HIGHER NW FACING TERRAIN OF WRN AND ERN SECTIONS OF THE CWA DOWNWIND
OF LAKE SUPERIOR. AN ADVISORY HEADLINE MAY EVENTUALLY BE NEEDED
DURING THIS TIME FRAME BUT FOR NOW WILL CONTINUE WORDING OF SEVERAL
INCHES OF ACCUMULATING SNOW IN THE HWO.
SUNDAY THROUGH TUESDAY...MODELS IN GENERAL AGREEMENT WITH A
TRANSITION TOWARD A MORE ZONAL FLOW PATTERN FOR EARLY NEXT WEEK. A
WEAK WNW FLOW SHORTWAVE MOVING THROUGH SAT NIGHT INTO SUNDAY COULD
BRING SOME LIGHT SNOW TO MAINLY THE NRN AND ERN PORTIONS OF THE CWA.
A WEAK N-NE FLOW SETTING UP FOR MON INTO TUE BTWN HIGH PRESSURE OVER
SCNTRL CANADA/NRN PLAINS AND LOW PRESSURE DVLPG OVER THE SRN/CENTRAL
PLAINS WILL CONTINUE TO WARRANT LOW CHC POPS FOR LIGHT LES WITH 8H
TEMPS LINGERING AROUND -14C.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 711 AM EST WED NOV 21 2012
VLIFG STATUS AND FOG AT CMX AND SAW IS EXPECTED LIFT TO VFR
CONDITIONS BY MID TO LATE MORNING WITH THE ONSET OF DAYTIME HEATING
AND AS DRIER AIR MOVES IN FROM THE WEST. OTHERWISE...VFR CONDITIONS
SHOULD PREVAIL INTO THIS EVENING. AN INCREASING SW LOW LEVEL JET
THIS EVENING WILL RESULT IN LOW LEVEL WIND SHEAR. THE STRONGER WINDS
SHOULD PROVIDE ENOUGH MIXING TO REDUCE THREAT FOR ADDITIONAL FOG
FORMATION. HOWEVER...THERE MAY BE ENOUGH UPSLOPE COMPONENT WITH SRLY
SFC WINDS FOR MVFR BR AT SAW. ALTHOUGH IFR CONDITIONS CANNOT BE
RULET OUT...CONFIDENCE WAS LOWR THAT ANY LOWER STRATUS DECK OR
THICKER FOG WOULD DEVELOP.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 608 AM EST WED NOV 21 2012
WINDS SHOULD REMAIN BELOW 20 KNOTS THROUGH THURSDAY MORNING AS HIGH
PRESSURE REMAINS IN CONTROL OF THE REGION. WINDS WILL SHIFT FROM THE
SOUTH THURSDAY AFTERNOON TO THE NORTHWEST AND INCREASE TO GALES TO
35 KNOTS BY FRIDAY MORNING AS THE PRESSURE GRADIENT INCREASES ACROSS
THE AREA. GALES ARE ARE EXPECTED TO DIMINISH BY FRIDAY EVENING OVER
WESTERN LAKE SUPERIOR AND OVER THE EAST LATE FRIDAY NIGHT. WINDS
SHOULD REMAIN BELOW 20 KNOTS FROM SATURDAY AFTERNOON THROUGH THE
REMAINDER OF THE PERIOD.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WATCH FROM LATE THURSDAY NIGHT THROUGH LATE FRIDAY NIGHT
FOR LSZ264>267.
GALE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY EVENING FOR
LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KC
SHORT TERM...JLB
LONG TERM...VOSS
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
714 AM EST WED NOV 21 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 608 AM EST WED NOV 21 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL RIDGE
FROM THE SOUTHERN AND CENTRAL PLAINS INTO THE WESTERN GREAT LAKES
AND A TROUGH FROM THE GULF OF ALASKA INTO THE PACIFIC NORTHWEST. A
VIGOROUS SHORTWAVE TROUGH WAS MOVING ONSHORE INTO OR AND SOUTHERN
WA. AT THE SURFACE...SOUTHERLY FLOW WAS INCREASING BETWEEN HIGH PRES
BUILDING INTO THE EASTERN GREAT LAKES AND A TROUGH FROM NW ONTARIO
INTO EASTERN NORTH DAKOTA.
WITH ABUNDANT LOW LEVEL MOISTURE OVER THE AREA...DEWPOINTS INTO THE
MID AND UPPER 30S...AREAS OF DENSE FOG HAVE DEVELOPED OVER INTERIOR
PORTIONS OF CENTRAL UPPER MICHIGAN AND OVER THE HIGHER TERRAIN OF
THE KEWEENAW. INCREASING WINDS AND DRY ADVECTION HAS HELPED REDUCE
FOG COVERAGE/DENSITY.
TODAY...EXPECT ANY LINGERING FOG TO DISSIPATE EARLY WITH THE DRY
ADVECTION FROM THE WEST AND THE ONSET OF DAYTIME HEATING LEAVING
CLEARING SKIES. WAA WILL PUSH 850 MB TEMPERATURES ARE EXPECTED TO
REACH TO AROUND 10C...HOWEVER THE WEAK NOVEMBER SUNSHINE WILL LIMIT
TEMPERATURES TO THE MID TO UPPER 50S...WITH THE WARMER TEMPERATURES
OVER THE DOWNSLOPE LOCATIONS FAVORED BY A SOUTHERLY WIND. SOUTHERLY
WINDS WILL CONTINUE TO INCREASE OVER THE REGION AS THE PRESSURE
GRADIENT INCREASES BETWEEN LOW PRESSURE APPROACHING FROM THE
NORTHWEST AND THE HIGH TO THE SOUTHEAST.
TONIGHT...LOW PRES WILL MOVE TO NORTH OF KINL KEEPING BREEZY SOUTH
WINDS GOING. SO...LOW TEMPS WILL NOT FALL OF MUCH WITH MIN READINGS
ONLY IN THE LOWER TO MID 40S. THIS COULD AGAIN RESULT IN RECORD HIGH
LOW MINS FOR MANY LOCATIONS. THE WIND AND MIXING SHOULD ALSO
MINIMIZE POTENTIAL FOR FOG FORMATION EVEN THOUGH DEWPOINTS REMAIN
AROUND 40.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 608 AM EST WED NOV 21 2012
THANKSGIVING WILL MARK THE LAST DAY OF UNSEASONABLY WARM WEATHER FOR
AWHILE AS A SW FLOW CONTINUES TO BRING WARM AIR OVER THE GREAT LAKES
REGION AHEAD OF A FAST-APPROACHING STRONG SHORTWAVE MOVING IN FM THE
NRN PLAINS. DESPITE INCREASING WAA CLOUDS IN THE AFTERNOON AHEAD OF
THE INCOMING SHORTWAVE...MIXING TO JUST 900 MB AS INDICATED ON NAM
FCST SNDGS WOULD EASILY YIELD HIGH TEMPS IN THE MID 50S ACROSS MUCH
OF THE AREA. UPPER 50S COULD EVEN BE REACHED FOR WEST HALF LOCATIONS
ALONG LAKE SUPERIOR IN DOWNSLOPE SSW FLOW. RECORD TEMP OF 54F ON THE
22ND MAY BE IN JEOPARDY AT THE MQT NWS OFFICE. TEMPS WILL STAY A BIT
COOLER (LOW 50S) ALONG LAKE MICHIGAN SHORE IN SSW FLOW. INCREASING
MID-LVL MOISTURE AND DPVA TOWARD EVENING COULD BRING IN SOME ISOLD
SHRA LATE INTO THE WESTERN CWA SO HAVE KEPT IN SLIGHT CHC
POPS.
THURSDAY NIGHT AND FRIDAY...FOLLOWED ALONG NCEP PREFERRED BLEND OF
00Z GFS AND ECMWF WHICH ADVERTISES A SLOWER AND MORE AMPLIFIED SOLN
WITH THE NRN PLAINS SHORTWAVE AND ASSOC FRONTAL SYSTEM THAN THE NAM
OR THE CANADIAN MODELS. THE GFS AND ECMWF BLENDED SOLN ALSO HAS
SUPPORT FM THE 00Z UKMET RUN. COMPROMISE SOLN WOULD TAKE
SHORTWAVE/5H CLOSED LOW ACROSS NRN WI/CENTRAL UPR MI WITH WINDS
SHIFTING FROM WEST BEHIND INITIAL COLD FROPA IN THE EVENING TO THE
NORTHWEST OVERNIGHT BEHIND PASSAGE OF MAIN SHORTWAVE/5H TROUGH AND
SECONDARY COLD FRONT. IT IS BEHIND THIS SECONDARY COLD FRONT AND
ADVECTION OF -10 TO -12C 8H AIR OVER WRN LAKE SUPERIOR THAT LAKE
EFFECT PCPN WL QUICKLY CHANGEOVER TO SNOW LATE THU NIGHT INTO EARLY
FRIDAY. THERE COULD ALSO BE SEVERAL HOUR PERIOD OF ENHANCEMENT AS
SHORTWAVE AND ASSOC DEEP LYR Q-VECT CONV SPREADS QUICKLY ACROSS THE
AREA. ENHANCEMENT WILL BE LOST BY LATE FRI AFTERNOON AS SHORTWAVE
EXITS EAST OF THE AREA AND EVENT WILL TRANSITION TO PURE LAKE EFFECT
SNOW AS 8H TEMPS LOWER TO AROUND -15C.
FRIDAY NIGHT INTO SATURDAY...THERE MAY BE A BRIEF PERIOD FOR
ADDITIONAL ENHANCEMENT TO SNOW FRI EVENING WITH MODELS HINTING AT
ANOTHER WEAK CLIPPER SHORTWAVE MOVING ACROSS THE AREA BUT AFTER THAT
MODELS ARE IN GOOD AGREEMENT WITH STRONG RDG BUILDING IN FM NW OF
LAKE SUPERIOR. STRONG SUBSIDENCE ASSOC WITH THIS RDG WILL SHARPLY
LOWER INVERSION HGTS TO BLO 4KFT OVER THE WEST BY 12Z SAT WHICH
SHOULD QUICKLY DIMINISH LES TO FLURRIES EARLY SATURDAY. LONGER FETCH
IN NW FLOW ACROSS ERN LAKE SUPERIOR WILL ALLOW SOME LES TO
ACCUMULATE INTO SAT MORNING BUT THEN STRONG SUBSIDENCE AND DRYING
SHOULD DIMINISH ANY REMAINING LES TO FLURRIES BY AFTERNOON.
TOTAL SNOW ACCUMULATION DURING THE EVENT FM THU NIGHT INTO EARLY
SATURDAY WILL LIKELY REACH 3-7 INCHES WITH THE HIGHEST AMOUNTS OVER
HIGHER NW FACING TERRAIN OF WRN AND ERN SECTIONS OF THE CWA DOWNWIND
OF LAKE SUPERIOR. AN ADVISORY HEADLINE MAY EVENTUALLY BE NEEDED
DURING THIS TIME FRAME BUT FOR NOW WILL CONTINUE WORDING OF SEVERAL
INCHES OF ACCUMULATING SNOW IN THE HWO.
SUNDAY THROUGH TUESDAY...MODELS IN GENERAL AGREEMENT WITH A
TRANSITION TOWARD A MORE ZONAL FLOW PATTERN FOR EARLY NEXT WEEK. A
WEAK WNW FLOW SHORTWAVE MOVING THROUGH SAT NIGHT INTO SUNDAY COULD
BRING SOME LIGHT SNOW TO MAINLY THE NRN AND ERN PORTIONS OF THE CWA.
A WEAK N-NE FLOW SETTING UP FOR MON INTO TUE BTWN HIGH PRESSURE OVER
SCNTRL CANADA/NRN PLAINS AND LOW PRESSURE DVLPG OVER THE SRN/CENTRAL
PLAINS WILL CONTINUE TO WARRANT LOW CHC POPS FOR LIGHT LES WITH 8H
TEMPS LINGERING AROUND -14C.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 711 AM EST WED NOV 21 2012
VLIFG STATUS AND FOG AT CMX AND SAW IS EXPECTED LIFT TO VFR
CONDITIONS BY MID TO LATE MORNING WITH THE ONSET OF DAYTIME HEATING
AND AS DRIER AIR MOVES IN FROM THE WEST. OTHERWISE...VFR CONDITIONS
SHOULD PREVAIL INTO THIS EVENING. AN INCREASING SW LOW LEVEL JET
THIS EVENING WILL RESULT IN LOW LEVEL WIND SHEAR. THE STRONGER WINDS
SHOULD PROVIDE ENOUGH MIXING TO REDUCE THREAT FOR ADDITIONAL FOG
FORMATION. HOWEVER...THERE MAY BE ENOUGH UPSLOPE COMPONENT WITH SRLY
SFC WINDS FOR MVFR BR AT SAW. ALTHOUGH IFR CONDITIONS CANNOT BE
RULET OUT...CONFIDENCE WAS LOWR THAT ANY LOWER STRATUS DECK OR
THICKER FOG WOULD DEVELOP.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 608 AM EST WED NOV 21 2012
WINDS SHOULD REMAIN BELOW 20 KNOTS THROUGH THURSDAY MORNING AS HIGH
PRESSURE REMAINS IN CONTROL OF THE REGION. WINDS WILL SHIFT FROM THE
SOUTH THURSDAY AFTERNOON TO THE NORTHWEST AND INCREASE TO GALES TO
35 KNOTS BY FRIDAY MORNING AS THE PRESSURE GRADIENT INCREASES ACROSS
THE AREA. GALES ARE ARE EXPECTED TO DIMINISH BY FRIDAY EVENING OVER
WESTERN LAKE SUPERIOR AND OVER THE EAST LATE FRIDAY NIGHT. WINDS
SHOULD REMAIN BELOW 20 KNOTS FROM SATURDAY AFTERNOON THROUGH THE
REMAINDER OF THE PERIOD.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
DENSE FOG ADVISORY UNTIL 8 AM EST /7 AM CST/ THIS MORNING FOR
MIZ001-003>005-010>013-084.
LAKE SUPERIOR...
GALE WATCH FROM LATE THURSDAY NIGHT THROUGH LATE FRIDAY NIGHT
FOR LSZ264>267.
GALE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY EVENING FOR
LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...VOSS
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
610 AM EST WED NOV 21 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 608 AM EST WED NOV 21 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL RIDGE
FROM THE SOUTHERN AND CENTRAL PLAINS INTO THE WESTERN GREAT LAKES
AND A TROUGH FROM THE GULF OF ALASKA INTO THE PACIFIC NORTHWEST. A
VIGOROUS SHORTWAVE TROUGH WAS MOVING ONSHORE INTO OR AND SOUTHERN
WA. AT THE SURFACE...SOUTHERLY FLOW WAS INCREASING BETWEEN HIGH PRES
BUILDING INTO THE EASTERN GREAT LAKES AND A TROUGH FROM NW ONTARIO
INTO EASTERN NORTH DAKOTA.
WITH ABUNDANT LOW LEVEL MOISTURE OVER THE AREA...DEWPOINTS INTO THE
MID AND UPPER 30S...AREAS OF DENSE FOG HAVE DEVELOPED OVER INTERIOR
PORTIONS OF CENTRAL UPPER MICHIGAN AND OVER THE HIGHER TERRAIN OF
THE KEWEENAW. INCREASING WINDS AND DRY ADVECTION HAS HELPED REDUCE
FOG COVERAGE/DENSITY.
TODAY...EXPECT ANY LINGERING FOG TO DISSIPATE EARLY WITH THE DRY
ADVECTION FROM THE WEST AND THE ONSET OF DAYTIME HEATING LEAVING
CLEARING SKIES. WAA WILL PUSH 850 MB TEMPERATURES ARE EXPECTED TO
REACH TO AROUND 10C...HOWEVER THE WEAK NOVEMBER SUNSHINE WILL LIMIT
TEMPERATURES TO THE MID TO UPPER 50S...WITH THE WARMER TEMPERATURES
OVER THE DOWNSLOPE LOCATIONS FAVORED BY A SOUTHERLY WIND. SOUTHERLY
WINDS WILL CONTINUE TO INCREASE OVER THE REGION AS THE PRESSURE
GRADIENT INCREASES BETWEEN LOW PRESSURE APPROACHING FROM THE
NORTHWEST AND THE HIGH TO THE SOUTHEAST.
TONIGHT...LOW PRES WILL MOVE TO NORTH OF KINL KEEPING BREEZY SOUTH
WINDS GOING. SO...LOW TEMPS WILL NOT FALL OF MUCH WITH MIN READINGS
ONLY IN THE LOWER TO MID 40S. THIS COULD AGAIN RESULT IN RECORD HIGH
LOW MINS FOR MANY LOCATIONS. THE WIND AND MIXING SHOULD ALSO
MINIMIZE POTENTIAL FOR FOG FORMATION EVEN THOUGH DEWPOINTS REMAIN
AROUND 40.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 608 AM EST WED NOV 21 2012
THANKSGIVING WILL MARK THE LAST DAY OF UNSEASONABLY WARM WEATHER FOR
AWHILE AS A SW FLOW CONTINUES TO BRING WARM AIR OVER THE GREAT LAKES
REGION AHEAD OF A FAST-APPROACHING STRONG SHORTWAVE MOVING IN FM THE
NRN PLAINS. DESPITE INCREASING WAA CLOUDS IN THE AFTERNOON AHEAD OF
THE INCOMING SHORTWAVE...MIXING TO JUST 900 MB AS INDICATED ON NAM
FCST SNDGS WOULD EASILY YIELD HIGH TEMPS IN THE MID 50S ACROSS MUCH
OF THE AREA. UPPER 50S COULD EVEN BE REACHED FOR WEST HALF LOCATIONS
ALONG LAKE SUPERIOR IN DOWNSLOPE SSW FLOW. RECORD TEMP OF 54F ON THE
22ND MAY BE IN JEOPARDY AT THE MQT NWS OFFICE. TEMPS WILL STAY A BIT
COOLER (LOW 50S) ALONG LAKE MICHIGAN SHORE IN SSW FLOW. INCREASING
MID-LVL MOISTURE AND DPVA TOWARD EVENING COULD BRING IN SOME ISOLD
SHRA LATE INTO THE WESTERN CWA SO HAVE KEPT IN SLIGHT CHC
POPS.
THURSDAY NIGHT AND FRIDAY...FOLLOWED ALONG NCEP PREFERRED BLEND OF
00Z GFS AND ECMWF WHICH ADVERTISES A SLOWER AND MORE AMPLIFIED SOLN
WITH THE NRN PLAINS SHORTWAVE AND ASSOC FRONTAL SYSTEM THAN THE NAM
OR THE CANADIAN MODELS. THE GFS AND ECMWF BLENDED SOLN ALSO HAS
SUPPORT FM THE 00Z UKMET RUN. COMPROMISE SOLN WOULD TAKE
SHORTWAVE/5H CLOSED LOW ACROSS NRN WI/CENTRAL UPR MI WITH WINDS
SHIFTING FROM WEST BEHIND INITIAL COLD FROPA IN THE EVENING TO THE
NORTHWEST OVERNIGHT BEHIND PASSAGE OF MAIN SHORTWAVE/5H TROUGH AND
SECONDARY COLD FRONT. IT IS BEHIND THIS SECONDARY COLD FRONT AND
ADVECTION OF -10 TO -12C 8H AIR OVER WRN LAKE SUPERIOR THAT LAKE
EFFECT PCPN WL QUICKLY CHANGEOVER TO SNOW LATE THU NIGHT INTO EARLY
FRIDAY. THERE COULD ALSO BE SEVERAL HOUR PERIOD OF ENHANCEMENT AS
SHORTWAVE AND ASSOC DEEP LYR Q-VECT CONV SPREADS QUICKLY ACROSS THE
AREA. ENHANCEMENT WILL BE LOST BY LATE FRI AFTERNOON AS SHORTWAVE
EXITS EAST OF THE AREA AND EVENT WILL TRANSITION TO PURE LAKE EFFECT
SNOW AS 8H TEMPS LOWER TO AROUND -15C.
FRIDAY NIGHT INTO SATURDAY...THERE MAY BE A BRIEF PERIOD FOR
ADDITIONAL ENHANCEMENT TO SNOW FRI EVENING WITH MODELS HINTING AT
ANOTHER WEAK CLIPPER SHORTWAVE MOVING ACROSS THE AREA BUT AFTER THAT
MODELS ARE IN GOOD AGREEMENT WITH STRONG RDG BUILDING IN FM NW OF
LAKE SUPERIOR. STRONG SUBSIDENCE ASSOC WITH THIS RDG WILL SHARPLY
LOWER INVERSION HGTS TO BLO 4KFT OVER THE WEST BY 12Z SAT WHICH
SHOULD QUICKLY DIMINISH LES TO FLURRIES EARLY SATURDAY. LONGER FETCH
IN NW FLOW ACROSS ERN LAKE SUPERIOR WILL ALLOW SOME LES TO
ACCUMULATE INTO SAT MORNING BUT THEN STRONG SUBSIDENCE AND DRYING
SHOULD DIMINISH ANY REMAINING LES TO FLURRIES BY AFTERNOON.
TOTAL SNOW ACCUMULATION DURING THE EVENT FM THU NIGHT INTO EARLY
SATURDAY WILL LIKELY REACH 3-7 INCHES WITH THE HIGHEST AMOUNTS OVER
HIGHER NW FACING TERRAIN OF WRN AND ERN SECTIONS OF THE CWA DOWNWIND
OF LAKE SUPERIOR. AN ADVISORY HEADLINE MAY EVENTUALLY BE NEEDED
DURING THIS TIME FRAME BUT FOR NOW WILL CONTINUE WORDING OF SEVERAL
INCHES OF ACCUMULATING SNOW IN THE HWO.
SUNDAY THROUGH TUESDAY...MODELS IN GENERAL AGREEMENT WITH A
TRANSITION TOWARD A MORE ZONAL FLOW PATTERN FOR EARLY NEXT WEEK. A
WEAK WNW FLOW SHORTWAVE MOVING THROUGH SAT NIGHT INTO SUNDAY COULD
BRING SOME LIGHT SNOW TO MAINLY THE NRN AND ERN PORTIONS OF THE CWA.
A WEAK N-NE FLOW SETTING UP FOR MON INTO TUE BTWN HIGH PRESSURE OVER
SCNTRL CANADA/NRN PLAINS AND LOW PRESSURE DVLPG OVER THE SRN/CENTRAL
PLAINS WILL CONTINUE TO WARRANT LOW CHC POPS FOR LIGHT LES WITH 8H
TEMPS LINGERING AROUND -14C.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1234 AM EST WED NOV 21 2012
TOUGH FORECAST OVERNIGHT FOR ALL TAF SITES AND CONFIDENCE IS LOW.
LOW LEVEL MOISTURE IS TRAPPED UNDER AN INVERSION AND THIS IS CAUSING
FOG WITH LOW VIS AND LOW CLOUDS. KIWD IS ON EDGE OF THIS AND HAS
MANAGED TO DOWNSLOPE THE FOG AND STRATUS OUT AND EXPECT THAT TO
CONTINUE OVERNIGHT. CMX AND SAW WILL CONTINUE WITH LOWER VIS AND FOG
OVERNIGHT. THIS MIXES OUT IN THE MORNING AND VFR CONDITIONS WILL
THEN CONTINUE. UPSLOPE FOG AND STRATUS WILL DEVELOP AGAIN WED
EVENING FOR SAW FROM LAKE MICHIGAN. LLWS IS ALSO POSSIBLE WED
EVENING AT SAW AND IWD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 608 AM EST WED NOV 21 2012
WINDS SHOULD REMAIN BELOW 20 KNOTS THROUGH THURSDAY MORNING AS HIGH
PRESSURE REMAINS IN CONTROL OF THE REGION. WINDS WILL SHIFT FROM THE
SOUTH THURSDAY AFTERNOON TO THE NORTHWEST AND INCREASE TO GALES TO
35 KNOTS BY FRIDAY MORNING AS THE PRESSURE GRADIENT INCREASES ACROSS
THE AREA. GALES ARE ARE EXPECTED TO DIMINISH BY FRIDAY EVENING OVER
WESTERN LAKE SUPERIOR AND OVER THE EAST LATE FRIDAY NIGHT. WINDS
SHOULD REMAIN BELOW 20 KNOTS FROM SATURDAY AFTERNOON THROUGH THE
REMAINDER OF THE PERIOD.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
DENSE FOG ADVISORY UNTIL 8 AM EST /7 AM CST/ THIS MORNING FOR
MIZ001-003>005-010>013-084.
LAKE SUPERIOR...
GALE WATCH FROM LATE THURSDAY NIGHT THROUGH LATE FRIDAY NIGHT
FOR LSZ264>267.
GALE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY EVENING FOR
LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...VOSS
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
950 AM EST WED NOV 21 2012
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OVER THE EASTERN US THROUGH THANKSGIVING.
A PAIR OF MOISTURE-STARVED COLD FRONTS WILL CROSS THE MIDDLE
ATLANTIC REGION FRIDAY NIGHT.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 950 AM WEDNESDAY...
AS THE SHORTWAVE TROUGH ALOFT OVER THE SOUTHEAST CONTINUES TO DIG
SOUTHEAST...THE PATCHY CLOUDS ASSOCIATED WITH THE WAVE...MAINLY
OVER THE SOUTHWEST PIEDMONT INTO SOUTH CAROLINA...HAVE ALSO MOVED
SOUTHEAST AND ERODED SOMEWHAT WITH TIME ON SATELLITE IMAGERY. THE
LATEST NAM AND RUC GUIDANCE ARE FAIRLY SIMILAR IN SHOWING SOME
UPPER-LEVEL MOISTURE ESPECIALLY TOWARD KFAY INTO THIS AFTERNOON...
WITH DRYING EVEN IN THE UPPER LEVELS THERE DURING THE AFTERNOON.
PATCHY LOW CLOUDS WERE ERODING AS WELL...AND WITH A DRY AND STABLE
OVERALL AIR MASS...ANTICIPATE CONSIDERABLE SUNSHINE WITH MOSTLY
SCATTERED CLOUDS MOVING EAST FROM THE SOUTHWEST PIEDMONT ACROSS THE
SANDHILLS. AREAS ALONG AND SOUTH OF A LINE FROM ABOUT KAFP TO KCTZ
INCLUDING KFAY COULD HAVE A PERIOD OF BROKEN MID-LEVEL CLOUDS...BUT
THE DAY SHOULD STILL AVERAGE MOSTLY SUNNY. MORNING 1000-850MB
THICKNESSES WHEN COMBINED WITH ANTICIPATED VALUES IN THE AFTERNOON
CORRESPOND WELL WITH MOS GUIDANCE AND ONGOING HIGHS...AND ALTHOUGH
MIXING WILL STRUGGLE TO REACH TO 850MB...GIVEN THE BETTER INSOLATION
OF TODAY AS COMPARED TO TUESDAY...WILL ANTICIPATE SIMILAR HIGHS...
AROUND 60. THERE WILL BE SOME WIND GUSTS IN THE TEENS KNOTS...
HIGHEST TOWARD INTERSTATE 95 WHERE ALREADY KCTZ NOTED A GUST IN THE
UPPER TEENS KNOTS JUST AFTER 1430Z. THIS WOULD BE ABOUT THE MAXIMUM
GUST ANTICIPATED BASED ON THE CONSENSUS OF THE LATEST GFS AND NAM
BUFR SOUNDINGS. -DJF
TONIGHT...RIDGING AND HEIGHT RISES ALOFT IN THE WAKE OF THE TROUGH
AXIS WILL YIELD CLEAR AND ASSOCIATED CHILLY CONDITIONS TONIGHT.
PERSISTENCE LOWS IN THE LOWER 30S TO NEAR 40 DEGREES...HIGHEST
AMIDST NORTHERLY STIRRING WITHIN THE TIGHTEST PRESSURE GRADIENT OVER
THE COASTAL PLAIN.
THANKSGIVING DAY...CONTINUED RIDGING AND HEIGHT RISES ALOFT AND
ASSOCIATED SUBSIDENCE WILL YIELD SUNNY AND CONTINUED MILD WEATHER
FOR THANKSGIVING...WITH HIGH TEMPERATURES AGAIN IN THE UPPER 50S TO
LOWER 60S. FURTHER DEEPENING OF THE WESTERN ATLANTIC LOW AND...AN
ASSOCIATED CONTINUED RELATIVE MAXIMUM IN THE PRESSURE GRADIENT OVER
EASTERN NC...WILL RESULT IN A NOTICEABLE NNE 10-15 MPH BREEZE AGAIN
WITH GUSTS TO NEAR 20 MPH INVOF AND ESPECIALLY EAST OF I-95...WITH
LIGHTER WIND TO THE WEST.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 130 AM WEDNESDAY...
HIGH PRESSURE IN PLACE TO START THE PERIOD DAMPENS QUICKLY ON FRIDAY
AS A LOW PRESSURE SYSTEM AND ASSOCIATED SURFACE COLD FRONT APPROACH
THE AREA. ALTHOUGH WARM AIR WILL BE ADVECTING INTO CENTRAL NC OUT
AHEAD OF THE FRONT...ITS SOURCE IS A DRY CONTINENTAL AIRMASS WITHOUT
MUCH MOISTURE ADVECTION FROM THE GULF. THE GFS CONTINUES TO SHOW
WESTERLY FLOW ABOVE THE BOUNDARY LAYER WEST OF THE MTNS...WHICH
SUPPORTS DOWNSLOPE FLOW. THUS...EXPECT A DRY FRONTAL PASSAGE FRIDAY
AFTERNOON. GIVEN THE MOISTURE IN THE UPPER LEVELS THERE WILL LIKELY
BE HIGH CLOUDS OUT AHEAD OF THE FRONT AND WITH THE MOISTURE
CONVERGENCE ALONG THE FRONT...EXPECT A LAYER OF CLOUDS NEAR 850 MB
ALONG THE FRONT WITH DRYING FROM THE TOP DOWN BEHIND IT. LOW TEMPS
THURSDAY NIGHT IN THE MID TO UPPER 30S. WITH THE WARM ADVECTION
AHEAD OF THE FRONT HAVE HIGHS IN THE MID 60S FRIDAY...AND WITH
CURRENT TIMING OF THE FRONT EXPECT FRIDAY NIGHT LOWS IN THE MID 30S
NW TO LOW 40S SE.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 255 AM WEDNESDAY...
SATURDAY THROUGH MONDAY:
SKIES WILL CONTINUE CLEARING FROM NW TO SE ON SATURDAY AS THE COLD
FRONT PUSHES OFFSHORE. FORECAST 1000-850 MB THICKNESS VALUES
DECREASE BY APPROX 70 METERS FROM 00Z SATURDAY TO 00Z SUNDAY. WHILE
THIS IS LIKELY A LITTLE OVER DONE AND MAY NOT ACCOUNT FOR THE
ADIABATIC WARMING WITH THE STRONG NW WINDS OFF THE MTNS BEHIND THE
FRONT ON SATURDAY...TEMPS WILL STILL BE SIGNIFICANTLY COLDER THAN
FRIDAY...WITH HIGHS IN THE UPPER 40S NW TO MID 50S SE AND OVERNIGHT
LOWS IN THE UPPER 20S TO LOW 30S. AS SURFACE HIGH PRESSURE BUILDS
INTO THE AREA OVERNIGHT...THE MAIN UPPER LEVEL TROUGH AXIS WILL
SHIFT OFFSHORE. AS THE HIGH MOVES OVER CENTRAL NC AND OFF THE NC
COAST SUNDAY NIGHT...WINDS SPEEDS WILL DECREASE AT THE SURFACE AND
ALOFT WHILE SURFACE WINDS SHIFT FROM NW TO SW. WILL CONTINUE TO HAVE
WEST TO NORTHWEST WINDS ABOVE THE BOUNDARY LAYER WITH GOOD
SUBSIDENCE AND ADIABATIC WARMING...YIELDING A STRONG SUBSIDENCE
INVERSION AT THE TOP OF THE MIXED LAYER. LOW LEVEL THICKNESSES WILL
RECOVER SOME IN THE NW ON SUNDAY RESULTING IN TEMPS A COUPLE DEGREES
WARMER...LOW 50S... WHILE HIGHS ELSEWHERE WILL BE ABOUT THE SAME TO
A LITTLE COOLER THAN SATURDAY...LOW TO MID 50S. ALTHOUGH THE LOW
LEVEL THICKNESSES GRADUALLY INCREASE ACROSS THE AREA SUNDAY
NIGHT...CLEAR SKIES AND LIGHT WINDS NEAR THE SURFACE UNDER THE HIGH
WILL YIELD OVERNIGHT LOWS ONLY SLIGHTLY WARMER IN THE NW TO SIMILAR
TO THE PREVIOUS NIGHT ACROSS THE SE...MAINLY IN THE LOW 30S. IN
ADDITION TO THE INCREASING THICKNESSES...RELATIVELY WARM AIR WILL
BEGIN ADVECTING INTO CENTRAL NC FROM THE SSW ON MONDAY. AS SKIES
WILL REMAIN CLEAR TO PARTLY CLOUDY FOR MUCH OF THE DAY EXPECT HIGHS
IN THE MID 50S TO NEAR 60.
MONDAY NIGHT AND TUESDAY:
SURFACE LOW OVER THE TX PANHANDLE 00Z TUESDAY WILL MOVE EAST AND
THEN NE OVER THE MS RIVER VALLEY BY DAYBREAK TUESDAY. WILL SEE
INCREASING HIGH CLOUDS BEGINNING MONDAY EVENING. THIS LOW PRESSURE
SYSTEM WILL HAVE GOOD MOISTURE FEED INTO IT FROM THE GULF OF MEXICO
AS IT MOVES EASTWARD. AS THE WARM MOIST AIR ADVECTS INTO THE AREA ON
TUESDAY SKIES WILL QUICKLY BECOME OVERCAST AND AS THE TROUGH
APPROACHES SSW SURFACE WINDS WILL INCREASE. AS OF THE MOST RECENT
MODEL RUNS...COULD SEE PRECIP REACHING THE WESTERN PARTS OF OUR AREA
AROUND 18Z AND PROGRESSING EASTWARD THROUGH THE END OF THE PERIOD.
AS SUCH...WILL CARRY A SLIGHT CHANCE OF PRECIP ACROSS THE NW PRIOR
TO 12Z TUESDAY...INCREASING TO CHANCE IN THE NW TO SLIGHT CHANCE IN
THE SE BY 00Z WEDNESDAY. EXPECT MONDAY NIGHT LOWS IN THE UPPER 30S
TO LOW 40S WITH HIGHS ON TUESDAY IN THE MID 50S NW TO LOW 60S SE.
HOWEVER...TEMPS ON TUESDAY MAY CHANGE IF CHANGES IN TIMING OF PRECIP
OCCUR. GIVEN THAT THIS SYSTEM IS COMING IN AT THE END OF THE
FORECAST PERIOD AND THERE ARE STILL SOME DIFFERENCES IN TIMING
BETWEEN THE MODELS...CONFIDENCE IN EITHER PARAMETER IS NOT
PARTICULARLY HIGH AT THIS POINT IN TIME.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
AS OF 950 AM WEDNESDAY...
CONTINUED HIGH PRESSURE WILL RESULT IN VFR CONDITIONS THROUGH THE
TAF PERIOD. A NNE BREEZE WILL INCREASE INTO THE 8-12KT RANGE WITH
OCCASIONAL GUSTINESS INTO THE MID TEENS KTS AT EASTERN TERMINALS...
WITH LIGHTER WINDS TO THE WEST. WHILE NEAR SURFACE WINDS WILL BECOME
GENERALLY LIGHT (LESS THAN 5 KTS) TO CALM OVERNIGHT...NNE WINDS JUST
ABOVE THE SURFACE ARE FORECAST TO STRENGTHEN TO AROUND 30 KTS...AND
THIS MAY RESULT IN MARGINAL LOW LEVEL WIND SHEAR CONDITIONS BETWEEN
03-12Z...MAINLY EAST OF TRIAD TERMINALS.
LOOKING AHEAD: GENERALLY VFR CONDITIONS WILL PREVAIL IN HIGH
PRESSURE THROUGH THE END OF THE WORK WEEK. A PAIR OF DRY/VFR COLD
FRONTS WILL CROSS OUR REGION FRIDAY NIGHT...THE SECOND AND STRONGER
OF WHICH WILL USHER IN MUCH COOLER AIR WITH BREEZY/WINDY NW SURFACE
WINDS ON SATURDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS
NEAR TERM...DJF/MWS
SHORT TERM...KC
LONG TERM...KC
AVIATION...DJF/MWS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
522 AM CST WED NOV 21 2012
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
341 AM CST WED NOV 21 2012
AT 3 AM...DENSE FOG WAS REDUCING VISIBILITIES TO A QUARTER MILE OR
LESS GENERALLY EAST OF A LINE FROM MENOMINEE WISCONSIN TO OELWEIN
IOWA. WITH TEMPERATURES AT OR BELOW FREEZING ACROSS MONROE...
JUNEAU...ADAMS...JACKSON...AND CLARK COUNTIES THERE IS SOME
CONCERN THAT SOME LIGHT ICING IS OCCURRING. THIS COULD MAKE THE
MORNING COMMUTE HAZARDOUS. AS THE WINDS INCREASE THIS MORNING...THE
FOG WILL BEGIN TO DISSIPATE BETWEEN 15Z AND 17Z IN CENTRAL WISCONSIN
AND ON THE BLUFF TOPS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA.
MODEL SOUNDINGS SUGGEST THAT THE MISSISSIPPI AND WISCONSIN RIVER
VALLEYS WILL BE THE LAST TO CLEAR /BETWEEN 16Z AND 18Z/. FOR
SIMPLICITY...SET THE EXPIRATION TIME OF THE DENSE FOG ADVISORY AT
18Z. THIS WILL MAKE IT EASIER TO CLEAR OUT THE COUNTIES AS THE
VISIBILITIES IMPROVE THIS MORNING.
FOR THIS AFTERNOON...THE 21.00Z MODELS ARE IN GOOD AGREEMENT THAT
SKIES WILL BE MOSTLY SUNNY WHICH WILL ALLOW THE AREA TO MIX UP
INTO THE 950 TO 925 MB RANGE. THE DEEPEST MIXING WILL OCCUR
OUTSIDE OF THE MISSISSIPPI AND WISCONSIN RIVER VALLEYS. MANY AREAS
SOUTH OF THE INTERSTATE 94 CORRIDOR WILL WARM INTO THE LOWER AND
MID 60S...AND INTO THE MID AND UPPER 50S NORTH OF THIS INTERSTATE.
DUE TO THE FOG HOLDING ON LONGER /WHICH LEADS TO LESS MIXING/...THE
MISSISSIPPI AND WISCONSIN RIVER VALLEYS WILL LIKELY SEE THEIR HIGH
TEMPERATURES ONLY TOP OUT AROUND 60 DEGREES.
FOR TONIGHT...A TIGHT PRESSURE SURFACE GRADIENT WILL KEEP THE
SOUTH WINDS IN THE 10 TO 20 MPH RANGE. THIS WILL KEEP THE BOUNDARY
LAYER WELL MIXED...THUS PREVENTING A NOCTURNAL INVERSION FROM
FORMING. AS A RESULT...THE TEMPERATURES WILL ONLY FALL INTO THE
MID AND UPPER 40S.
ON THANKSGIVING DAY...A COLD FRONT WILL MOVE EAST THROUGH
SOUTHEAST MINNESOTA AND NORTHEAST IOWA DURING THE MORNING...AND
WESTERN WISCONSIN DURING THE AFTERNOON. THERE WILL BE ENOUGH
SUNSHINE FOR TEMPERATURES TO CLIMB INTO THE 55 TO 60 DEGREE RANGE...
AND THEN TEMPERATURES WILL FALL INTO THE MID AND UPPER 30S FOR
NORTHEAST IOWA AND SOUTHEAST MINNESOTA...AND IN THE LOWER AND
MID 40S FOR WESTERN WISCONSIN.
FOR THURSDAY NIGHT INTO FRIDAY...A STRONG SHORT WAVE TROUGH WILL
MOVE ACROSS NORTHERN MINNESOTA AND NORTHERN WISCONSIN. THIS SYSTEM
WILL PRODUCE MEASURABLE SNOW ACROSS THESE AREAS. THERE MAY BE EVEN
A DUSTING OF SNOW ACROSS TAYLOR COUNTY. WITH THE BUFKIT MODEL
SOUNDINGS SUGGESTING THAT THERE WILL BE STEEP 950 TO 850 MB LAPSE
RATES INCLUDED FLURRIES DURING THE OVERNIGHT AND ON FRIDAY FOR THE
REST OF THE AREA. EARLY RISERS FOR THE BLACK FRIDAY SALES WILL
ENCOUNTER WIND CHILLS RANGING FROM 10 TO 20 DEGREES.
.LONG TERM...SATURDAY THROUGH TUESDAY
341 AM CST WED NOV 21 2012
ON SATURDAY NIGHT...THE 21.00Z MODELS SUGGEST THAT A COLD FRONT
WILL MOVE EAST THROUGH THE FORECAST AREA. WITH THE 280 TO 270K
ISENTROPIC CONDENSATION PRESSURE DEFICITS RUNNING FROM 50 TO
100 MB AND THE SOUNDINGS SHOWING DRY AIR BELOW 8K FEET...KEPT THIS
PERIOD DRY FOR NOW.
FROM MONDAY NIGHT INTO TUESDAY...BOTH THE GFS AND ECMWF
DETERMINISTIC MODELS ARE SHOWING THE POTENTIAL FOR SOME MEASURABLE
SNOW TO FALL ACROSS THE AREA AS A LOW PRESSURE SYSTEM MOVES
FROM THE MID MISSISSIPPI RIVER VALLEY INTO THE EASTERN GREAT
LAKES. WHILE THESE MODELS ARE IN GOOD AGREEMENT THE 00Z GFS
ENSEMBLE MEMBERS SHOWED QUITE A FEW DIFFERENT SCENARIOS AMONG ITS
12 FAMILY MEMBERS. SOME OF THEM WERE IN AGREEMENT WITH THE
DETERMINISTIC GFS. MEANWHILE OTHERS SUGGESTED THAT THIS LOW WOULD
REMAIN WEAK AND STAY OVER THE SOUTHEAST UNITED STATES OR IT WOULD
TRACK FURTHER WEST WHICH WOULD RESULT IN MIXED PRECIPITATION. EVEN
THE 16 RUNS OF GEM SHOWED QUITE A FEW DIVERSE 500 MB PATTERNS. ALL
OF THIS LEADS TO LITTLE CONFIDENCE WITH THIS TIME PERIOD...SO KEPT
PRECIPITATION CHANCES AROUND 20 PERCENT.
&&
.AVIATION...TODAY AND TONIGHT
522 AM CST WED NOV 21 2012
AT KLSE...INCREASING SOUTH WINDS AHEAD OF LOW PRESSURE IN THE
DAKOTAS HAS BEEN HELPING TO GRADUALLY IMPROVE CONDITIONS.
ALTHOUGH CEILINGS ARE STILL LIFR...VISIBILITIES HAVE IMPROVED TO
IFR. THE COMBINATION OF THE WINDS ALONG WITH DAYTIME HEATING WILL
MIX OUT THE FOG AND STRATUS IN THE MISSISSIPPI RIVER VALLEY...
EXPECTED TO BE COMPELTED DISSIPATED BY 18Z. THE RAP MODEL...WHICH
DID A GOOD JOB YESTERDAY SUGGESTING THE FOG WOULD STAY IN PLACE
THROUGH THE DAY...TODAY AGREES ABOUT THE FOG AND STRATUS
DISSIPATING BY 18Z. VFR CONDITIONS ARE THEN EXPECTED THROUGH
TONIGHT WITH A DEEP DRY AIRMASS IN PLACE ABOVE THE VALLEY.
AT KRST...PLAN ON VFR CONDITIONS TO CONTINUE THROUGH TONIGHT.
REGARDING THE WINDS...SOUTH WINDS SHOULD HOLD AROUND 10 KT AT KLSE
THROUGH TONIGHT...BUT COULD GUST UP TO 20 KT THIS AFTERNOON.
CONFIDENCE ON THE GUSTS IS NOT HIGH ENOUGH TO INCLUDE AT THIS
TIME. WITH 40 KT WINDS ABOVE THE SURFACE AT 1500 FT...HAVE
INCLUDED LOW LEVEL WIND SHEAR FOR THE AFTERNOON. THE WINDS AT 1500
FT ARE PROGGED TO INCREASE TONIGHT TO 50 KT AS THE LOW PRESSURE
AREA DEEPENS OFF TO OUR WEST. AT KRST...SOUTH WINDS SHOULD
INCREASE TOWARDS 15 KT BY NOON WITH GUSTS UP TO 25 KT...AND
PERSIST THROUGH TONIGHT. WITH THE 50 KT SOUTHWEST WINDS AT 1500
FT TONIGHT...ENOUGH WIND DIFFERENCE EXISTS FOR A NEED TO INCLUDE
LOW LEVEL WIND SHEAR AT KRST AS WELL.
&&
.CLIMATE...
341 AM CST SUN NOV 18 2012
RECORD HIGH TEMPERATURES FOR TODAY/21ST AND THURSDAY/22ND. COOP
SITES ARE 7 AM-7 AM HIGHS...THUS 22ND HIGHS ARE 21.12Z TO 22.12Z.
LA CROSSE AND ROCHESTER ARE THE ONLY NON-COOP SITES.
FORECAST HIGH TEMPERATURES SUGGEST SOME OF THE RECORDS BELOW MAY
BE TIED OR BROKEN.
LOCATION TODAY/21ST THURSDAY/22ND
LA CROSSE WI 72/1990 59/1963
SPARTA WI 65/1990 70/1990
MEDFORD WI 59/1913 65/1990
LANCASTER WI 66/2003 66/1898
MAUSTON WI 67/2003 66/1990
ROCHESTER MN 69/1990 65/1913
AUSTIN MN 70/1990 58/1966
WINONA DAM 5A MN 60/2003 60/2001
WABASHA MN 61/1908 59/1908
CHARLES CITY IA 71/1990 62/1966
OELWEIN IA 71/1990 62/1966
DECORAH IA 71/1990 62/1908
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
522 AM CST WED NOV 21 2012
WI...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR WIZ017-029-032>034-
041>044-053>055-061.
MN...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR MNZ088-096.
IA...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR IAZ010-011-029-030.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...AJ
CLIMATE......JONES/DB/AJ/BOYNE
AREA FORECAST DISCUSSION
NWS EUREKA CA
935 AM PST WED NOV 21 2012
.UPDATE...
UPDATED SKY/WX/POP/QPF GRIDS TO ACCOUNT FOR LATEST SHORT-TERM
SATELLITE AND RADAR TRENDS. WV IMAGERY AND RUC ANALYSIS DEPICT
MAIN SHORTWAVE TROUGH AXIS PAST THE COAST AND ALREADY BEGINNING TO
PUSH EAST OF OUR CWA. THERE IS ALSO ANOTHER VORT MAX ROUNDING THE
BASE OF THE TROUGH AS IT LIFTS OUT AND HEIGHTS QUICKLY RISE THIS
AFTERNOON. RAPIDLY INCREASING SUBSIDENCE AND THE AMOUNT OF
CLEARING OCCURRING ON AND OFF THE COAST ON VISIBLE IMAGERY SUPPORT
CUTTING SHOWER CHANCES ALTOGETHER THERE...BUT THE LAST DISTURBANCE
LEAVES A SHRED OF DOUBT FOR SOME ISOLATED/WIDELY SCATTERED SHOWER
ACTIVITY LINGERING ACROSS THE MTS OF THE NORTHCOAST INTERIOR AND
MAINLY DEL NORTE COUNTY THIS AFTERNOON. OTHERWISE EXPECT CLEARING
SKIES HEADING INTO TONIGHT WITH VALLEY FOG AND CHILLY TEMPS BY
THANKSGIVING MORNING. SUNNY BUT SEASONABLY COOL THANKSGIVING STILL
ON TAP. AAD
&&
.PREV DISCUSSION... /ISSUED 350 AM PST WED NOV 21 2012/
SYNOPSIS...SHOWERS WILL DIMINISH THROUGH THE DAY TODAY WITH DRY
WEATHER RETURNING FOR THANKSGIVING DAY. RAIN CHANCES WILL RETURN
FOR AREAS PRIMARILY NORTH OF MENDOCINO COUNTY FRIDAY NIGHT INTO
SATURDAY.
SHORT TERM...A SHORTWAVE TROUGH WILL MOVE EAST OF THE REGION THIS
MORNING BRINGING AN END TO THE STRONGEST CONVECTION. HOWEVER WITH
COLD AIR ALOFT TODAY...SHOWER CHANCES WILL CONTINUE THROUGH THE
AFTERNOON. BY THIS EVENING UPPER LEVEL RIDGING WILL BEGIN TO BUILD
OVER THE WEST COAST. THIS SHOULD BRING ANY SHOWER ACTIVITY TO AN END
QUICKLY THIS EVENING...BUT WITH LINGERING LOW LEVEL MOISTURE
INTERIOR AND COASTAL VALLEYS WILL LIKELY FOG OVER TONIGHT INTO THE
MORNING HOURS ON THANKSGIVING. ONCE THE FOG MIXES OUT IN THE MORNING
TO EARLY AFTERNOON...GENERALLY CLEAR SKIES CAN BE EXPECTED FOR THE
REMAINDER OF THANKSGIVING WITH TEMPERATURES WARMING ABOVE NORMAL
WITH THE REGION IN THE HEART OF AN UPPER LEVEL RIDGE. RIDGING WILL
GENERALLY BE MAINTAINED THROUGH MUCH OF FRIDAY BEFORE A TROUGH AND
COLD FRONT DIVE SOUTH INTO THE NORTHERN HALF OF THE CWA FRIDAY NIGHT
INTO SATURDAY. THIS WILL BRING ANOTHER SHOT OF RAIN TO LOCATIONS
PRIMARILY NORTH OF MENDOCINO COUNTY THROUGH SATURDAY. RPA
LONG TERM...SUNDAY INTO WEDNESDAY. MODELS CONTINUE TO INDICATE A
BUILDING RIDGE OFFSHORE WHICH WILL MAINTAIN THE POSSIBILITY OF A
BACK DOOR FRONT CLIPPING THE AREA SUN OR MON. THE RIDGE IS FORECAST
TO SHIFT EAST MON INTO TUE WHICH WILL ALLOW FOR GENERALLY FAIR
WEATHER THROUGHOUT NW CALIFORNIA. AS SUCH, HAVE CONTINUED TO KEEP
POPS LOW LATE WEEKEND THROUGH MON. DESPITE A POSSIBLE BACKDOOR
FRONT, WEAK OFFSHORE FLOW IS LIKELY TO DEVELOP HELPING TO KEEP THE
LOWER ATMOSPHERE DRY. THIS WILL ALSO ALLOW FOR TEMPS TO WARM A BIT
ALONG THE COAST. KEPT TEMPS IN THE MID TO UPPER 50S DURING THIS
TIME, BUT MAY REACH INTO THE LOW 60S IF THE OFFSHORE FLOW DEVELOPS
WELL. BEYOND EARLY NEXT WEEK, BEGAN TO TREND THE POPS UPWARD TOWARD
CLIMO AS A LARGE UPPER TROUGH LOOKS TO BE APPROACHING BY LATE NEXT
WEEK. BFG
AVIATION...THE MOST ROBUST SHOWER ACTIVITY WILL COME TO AN END THIS
MORNING ACROSS NORTHWEST CALIFORNIA AS AN UPPER LEVEL SHORTWAVE
MOVES EAST OF THE AREA. HOWEVER A FEW LINGERING SHOWERS WILL
CONTINUE THROUGH THE DAY TODAY BEFORE FINALLY DIMINISHING THIS
EVENING AS UPPER LEVEL RIDGING BUILDS OVERHEAD. EXPECT MVFR
CONDITIONS AT THE COASTAL TAF SITES THIS MORNING...IMPROVING TO VFR
LATER THIS MORNING OR IN THE EARLY AFTERNOON. FARTHER
INLAND...TRAPPED LOW LEVEL MOISTURE IN INTERIOR VALLEYS MAY RESULT
IN PERIODS OF IFR THIS MORNING BEFORE IMPROVING TO VFR. VALLEY FOG
WILL DEVELOP TONIGHT AS SKIES CLEAR AND TEMPERATURES DROP. RPA
MARINE...AS OF 330AM A POST FRONTAL TROUGH IS NEARLY THROUGH THE
NRN WATERS AND CUTTING ACROSS WATERS S OF CAPE MENDOCINO ON ITS WAY
TO THE ENE. WINDS AHEAD OF THIS TROUGH ARE GENERALLY OUT OF THE SW
WITH THE HIGHEST WINDS N OF THE CAPE. BEHIND THIS TROUGH WINDS ARE
SHIFTING TO THE W AND NW AS A WEAK RIDGE BUILDS OVER THE REGION. A
WEAK SFC PRESSURE GRADIENT WILL PREVAIL THE NEXT FEW DAYS WITH LIGHT
TO MODERATE WINDS. MODELS SEEM TO BE FAIRLY CONSISTENT WITH A FRONT
COMING IN OVER THE WEEKEND THEN A SURGE OF HIGH PRESSURE BEHIND IT.
THUS NORTHERLY WINDS ARE FORECAST TO INCREASE ON SUN ALONG WITH
STEEP NORTHERLY WAVES. SEAS LOOK TO BE THE LARGEST IMPACT TODAY WITH
SOME SHORT PERIOD CHOP EARLY THIS MORNING AND A BUILDING W WAVE
GROUP. THE SHORT PERIOD CHOP IS EXPECTED TO DECAY QUICKLY THIS
MORNING AND MAY BE GONE BY SUNRISE. HOWEVER, THE W WAVES WILL
CONTINUE INTO LATE MORNING THEN SLOWLY SUBSIDE INTO EARLY THU
MORNING. SEAS WILL BOTTOM OUT ON THANKSGIVING AND MAY DROP AS LOW AS
4 TO 6 FT AT 11 SECONDS RIGHT UP NEAR THE COAST. SEAS WILL BUILD
AGAIN ON FRI AS ANOTHER WNW WAVE GROUP DEVELOPS. OVERALL, EASING
CONDITIONS THIS AFTERNOON THROUGH TURKEY DAY. BFG
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 3 AM PST THURSDAY PZZ450-455-470-475.
&&
$$
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AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1009 AM MST WED NOV 21 2012
.UPDATE...CURRENT FORECASTS STILL LOOKING ON TRACK. ANOTHER WARM
DAY EXPECTED WITH READINGS ABOVE NORMAL. WAVE CLOUD FORMING ALONG
NORTHERN FOOTHILLS WHICH MODELS AS WELL AS WRF SYNTHETIC SATELLITE
IMAGERY KEEP ALONG FOOTHILLS THROUGH THE AFTERNOON. SHOULD NOT BE
A FACTOR IN KEEPING TEMPS FROM REACHING THE 70S ACROSS THE
PLAINS. LOOKING LIKE DENVER MAY END UP A FEW DEGREES SHY OF THE
RECORD OF 73 DEGREES SET BACK IN 1974. WINDS TO INCREASE ACROSS
MOUNTAINS THROUGH THE DAY AS SOUTHWEST FLOW ALOFT INCREASES. COULD
STILL SEE SOME GUSTS AROUND 50 MPH TONIGHT. ACROSS PLAINS...LATEST
MODELS CONTINUE TO SHOW WEAK GRADIENT INTO THE EVENING. COLD FRONT
STILL ON TRACK TO MOVE ACROSS THE AREA AFTER MIDNIGHT. WINDS COULD
GET A BIT GUSTY ALONG FOOTHILLS AND ADJACENT PLAINS.
&&
.AVIATION...CURRENT TAF TRENDS STILL LOOKING ON TRACK. LATEST NAM
AND RUC SHOWING WEAK ANTICYCLONE ACROSS THE DENVER AREA AFTER 21Z
WITH WEAK EASTERLIES ACROSS AREA AIRPORTS. DRAINAGE WINDS TO
REDEVELOP DURING THE EVENING. COLD FRONT STILL ON TRACK TO MOVE
ACROSS THE AREA AFTER MIDNIGHT WITH WINDS SHIFTING TO THE
NORTHWEST AND BECOMING NORTHERLY BY 12Z. VFR TO CONTINUE WITH
UNLIMITED CEILINGS.
&&
.PREV DISCUSSION... /ISSUED 403 AM MST WED NOV 21 2012/
SHORT TERM...SOUTHWEST FLOW ALOFT WILL INCREASE TODAY AND TONIGHT
AS A TROUGH MOVES FROM THE PACIFIC NORTHWEST TO THE NORTHERN
ROCKIES. THIS PATTERN WILL BRING ONE MORE WARM DAY. AIRMASS WILL
WARM A COUPLE OF DEGREES FROM YESTERDAY. THERE IS A WAVE CLOUD OVER
FAR NORTHERN COLORADO AND WYOMING. MODELS SHOWING MOISTURE WILL HOLD
OFF FROM INCREASING UNTIL LATE THIS AFTERNOON AND EVENING. DO EXPECT
SOME WAVE CLOUDS THEN. DO NOT EXPECT MUCH FOR CLOUDS THIS MORNING OR
EARLY AFTERNOON...SO WE SHOULD GET GOOD HEATING. HIGHS WILL LIKELY
SURPASS YESTERDAY`S READINGS BY A COUPLE OF DEGREES...WHICH WILL PUT
A FEW LOCATIONS IN THE LOWER 70S.
COLD FRONT WILL PUSH THROUGH NORTHEAST COLORADO AFTER MIDNIGHT
TONIGHT. THIS WILL HELP TO KEEP THE AIRMASS MIXED...THUS LOW LYING
AREAS WILL NOT BE AS COLD AS PAST NIGHTS. WINDS WILL INCREASE OVER
THE MOUNTAINS AND HIGHER FOOTHILLS WITH GUSTS TO 50 MPH POSSIBLE.
MAY SEE SOME OF THE GUSTY WINDS MIX DOWN THE FOOTHILLS AND ACROSS
AREAS WEST OF I-25.
LONG TERM...OPERATIONAL MODELS STILL MARCH AN UPPER TROUGH
ACROSS THE NORTHERN ROCKY MTN STATES ON THURSDAY AND SLIDE A COLD
FRONT SOUTH ACROSS N-CENTRAL AND NERN COLORADO THURSDAY MORNING. A
RELATIVELY STG JET MAXIMA ROUNDING THE SOUTH SIDE OF THIS TROUGH
IS PROGGED TO PASS OVER THE COLORADO FRONT RANGE IN THE MORNING
AND BE OVER NERN COLORADO BY THE AFTERNOON. SHOULD SEE SOME OF
THIS HIGH ALTITUDE MOMENTUM MIXING DOWN TO THE GROUND DURING THE
DAY AS COLD AIR CONTINUES TO FUNNEL IN BEHIND THE COLD FRONT. THIS
FRONTAL SYSTEM LOOKS DRY...HOWEVER MAY STILL SEE A FEW LIGHT
OROGRAPHIC SNOW SHOWERS OVER THE PARK AND GORE RANGES WITH PASSAGE
OF THE 700-500 TROUGH AXIS IN THE MORNING. SHOULD ALSO SEE A
PERIOD OF STG W-NWLY BORA WINDS OVER THE HIGH MTN RIDGES AND EAST
FACING SLOPES OF THE FRONT RANGE DURING MAX COLD AIR ADVECTION
DURING THE MORNING AND EARLY AFTERNOON HRS. COULD SEE GUSTS IN THE
40-50 MPH RANGE. STRONG AND GUSTY N-NWLY WINDS ALSO A GOOD BET ON
THE PLAINS FOR MUCH OF THE DAY. BEST CHANCE FOR THESE WINDS
ROUGHLY EAST OF A FORT COLLINS TO LIMON LINE WHERE WINDS COULD
GUST 35-40 MPH. WIND SPEEDS IN BOTH AREAS ARE BELOW HIGH WIND
CRITERIA. OTHERWISE A COLDER DAY WITH TEMPERATURES SOME 15-20 DEG
F BELOW THOSE EXPECTED TODAY. HOWEVER THE 55 DEG F FCST FOR DENVER
IS STILL 6 DEG F ABOVE AVERAGE FOR THE DATE.
FOR FRIDAY...TEMPERATURES SLOW TO WARM EVEN THOUGH TEMPERATURE BEGIN
TO WARM ALOFT WITH AN UPPER RIDGE BUILDING IN OVER THE STATE. WITH
DOWNSLOPE FLOW DEVELOPING ALONG THE FRONT RANGE SHOULD SEE WARMEST
READINGS IN THIS AREA..BUT STILL NEAR TO SLIGHTLY ABOVE AVERAGE. MTN
RIDGE WILL ALSO CONTINUE TO DEAL WITH GUSTY W-NWLY WINDS WITH FAST
NWLY FLOW ALOFT.
FOR SATURDAY...A LARGE UPPER RIDGE WITH ITS ABOVE AVERAGE
TEMPERATURES AND LOW HUMIDITIES MOVES ACROSS THE STATE. ACCORDING TO
MODELS SHOULD SEE A 8-12 DEG F WARMUP IN SFC TEMPERATURES ON THE
PLAINS...AND NEARLY AS MUCH WARMING IN THE HIGH COUNTRY WITH LIGHTER
WINDS.
FOR SUNDAY THROUGH TUESDAY...THE WARM UPPER RIDGE OVER THE REGION
QUICKLY FLATTENS AND MOVES EAST OF THE AREA ON SUNDAY AS AN UPPER
LEVEL WAVE AMPLIFIES AS IT RACES SOUTHEAST OUT OF THE PACIFIC
NORTHWEST. OPERATIONAL MODELS SHOW THIS PROGRESSIVE UPPER AIR
SYSTEM REACHING COLORADO BY LATE ON SUNDAY. GFS MODEL EVEN SHOWS A
WEAK COLD FRONT DROPPING SOUTH INTO NERN COLORADO BEFORE ITS
ARRIVAL WHICH HELPS TO ELEVATE BNDRY LAYER MOISTURE ON THE PLAINS.
WHEREAS THE OTHER MODELS ABOUT 6-9 HOURS BEHIND THE GFS. ITS ON
MONDAY WHEN ESSENTIALLY ALL MODELS SHOW THE TROUGH HAVING THE
GREATEST IMPACT ON THE FORECAST AREA. TEMPERATURES AT THEIR
COLDEST UNDER MOSTLY CLOUDY TO OVERCAST SKIES. SINCE THE MAIN
BUNDLE OF ENERGY WITH THIS SYSTEM REMAINS NORTH OF COLORADO...DO
NOT SEE THIS SYSTEM BEING A BIG PRECIP PRODUCER FOR US. MONDAY
AFTERNOON NOW APPEARS TO BE TIME WHEN WE/LL SEE OUR BEST CHANCE
FOR PRECIP...I.E SNOW IN THE HIGH COUNTRY AND RAIN/SNOW AT LOWER
ELEVATIONS. COULD SEE LIGHT ACCUMULATION IN THE HIGH COUNTRY AND
POSSIBLY IN SPOTS ON THE PLACES...BUT TOO EARLY TO PIN DOWN.
SYSTEM MOVES OUT MONDAY NIGHT WITH DRIER AND SLIGHT WARMER
CONDITIONS EXPECTED FOR TUESDAY WITH A RETURN TO HIGH PRESSURE.
AVIATION...VFR CONDITIONS WILL PREVAIL TODAY WITH ONLY SOME HIGH
CLOUDS. SOUTHERLY WINDS THIS MORNING WILL WEAKEN AND SHIFT EASTERLY
THIS AFTERNOON. NORMAL DRAINAGE WINDS WILL DEVELOP THIS EVENING.
AFTER MIDNIGHT TONIGHT...A COLD FRONT WILL PUSH THROUGH THE AREA
BRINGING NORTHERLY WINDS BY 12Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....BAKER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
345 PM CST WED NOV 21 2012
...UPDATED SYNOPSIS AND SHORT TERM SECTIONS...
.SYNOPSIS...
ISSUED AT 343 PM CST WED NOV 21 2012
THE PERSISTENT LONGWAVE TROUGH CONTINUED TO BE THE PREVAILING
METEOROLOGICAL FEATURE ACROSS THE PACIFIC-NORTH AMERICA SECTOR. ON
THE SYNOPTIC SCALE, A FAIRLY INTENSE STORM SYSTEM WAS MOVING INLAND
WASHINGTON/SOUTHERN BRITISH COLUMBIA. BY WEDNESDAY AFTERNOON, THE
PRIMARY CIRCULATION CENTER WAS MOVING ACROSS THE CANADIAN ROCKIES.
THE STRONG CROSS-MOUNTAIN FLOW WAS KEEPING MSLP FAIRLY LOW ACROSS
ALL OF THE NORTHERN HIGH PLAINS (1001MB SURFACE LOW NEAR ALZADA,
MONTANA AT 21Z). A SUBSTANTIAL WARM SECTOR ENCOMPASSED MUCH OF THE
GREAT PLAINS FROM TEXAS TO SOUTH DAKOTA WITH WIDESPREAD 70S OBSERVED
THIS AFTERNOON. MSLP GRADIENT WAS STRONGEST FROM WESTERN IOWA INTO
SOUTHWESTERN KANSAS WHERE WINDS RANGED FROM 22 TO 27 KNOTS SUSTAINED
DURING THE AFTERNOON HOURS. OF NOTE AS WELL (WHICH WILL PLAY INTO
TONIGHTS FORECAST), WAS A SUBTROPICAL DISTURBANCE FROM NEW MEXICO TO
SOUTHWEST TEXAS WHICH YIELDED QUITE A BIT OF MID AND HIGH LEVEL
CLOUD COVER AND EVEN A FEW LIGHTNING STRIKES FROM SHOWERS AND
ISOLATED THUNDERSTORMS.
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 343 PM CST WED NOV 21 2012
FOR THE TIME PERIOD TONIGHT AND TOMORROW, THE GREATEST CHALLENGE IN
THE FORECAST WILL BE LOWS TONIGHT AND HOW MUCH CLOUD COVER AND WIND
WILL INFLUENCE OVERNIGHT TEMPERATURES. THE PREVIOUS FORECAST
ALREADY HAD A FAIRLY TIGHT GRADIENT IN LOW TEMPERATURES TONIGHT
(FROM 33F ACROSS FAR WEST CENTRAL KANSAS TO AROUND 51F ACROSS FAR
SOUTH CENTRAL KANSAS). THESE LOOK GOOD FOR THE MOST PART, BUT THE
LATEST RAP AND NAM12 MODELS SUGGEST TEMPERATURES WILL NOT GET MUCH
BELOW 60F SOUTHEAST OF A GREAT BEND TO ASHLAND LINE, AND GIVEN THE
SEMI OPAQUE SKY COVER FROM 300-500MB CLOUD (FROM THE SUBTROPICAL
SHORTWAVE TROUGH) AND THE SOUTHWEST WINDS CONTINUING 12 TO 16 KNOTS
IN THESE AREAS, REALLY CANNOT ARGUE AGAINST THESE WARM TEMPERATURES
TONIGHT. AS A RESULT, I HAVE BUMPED UP MIN TEMPS ABOUT 2 TO 4
DEGREES AND MOVED THE GRADIENT WESTWARD ABOUT 30 MILES OR SO
(EFFECTIVELY WARMING UP DODGE CITY LOW QUITE A BIT).
THE FORECAST FOR THANKSGIVING DAY WILL BE A LITTLE LESS COMPLICATED
AS MID-HIGH LEVEL CLOUD COVER WILL BE MOVING EAST OF THE AREA WITH
SURFACE WINDS BECOMING NORTHWESTERLY. WHILE COLD ADVECTION WILL
EXIST BEHIND THE FRONT, THE AIRMASS WILL BE MODIFIED BY DOWNSLOPE
AND INSOLATION WILL ALSO COUNTER THE COLD ADVECTION. HIGHS WILL
STILL BE ABOVE AVERAGE FOR THE DATE WITH TEMPERATURES WARMING INTO
THE 60S (LOWER 70S SOUTH CENTRAL KS). WITH THE INITIAL ISALLOBARIC
WIND SURGE/PRESSURE RISE WITH THE PASSAGE OF THE FRONT, WIND SPEEDS
WILL BE 22 TO 26 KNOTS MUCH LIKE TODAY, BUT THESE SPEEDS SHOULD ONLY
OCCUR DURING ABOUT A 3 OR 4 HOUR PERIOD BEFORE WINDS GRADUALLY
DECREASE BACK DOWN TO THE 18 TO 22 KT RANGE LATE IN THE DAY.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 248 PM CST WED NOV 21 2012
BY THE BEGINNING OF THE EXTENDED PERIOD ON THURSDAY NIGHT, A STRONG
UPPER LEVEL SHORTWAVE TROUGH WILL BE MOVING OUT OF THE NORTHERN
PLAINS INTO THE MIDWESTERN STATES AND GREAT LAKES REGION. A COLD
FRONT WILL BE LOCATED OVER SOUTHEAST KANSAS INTO WEST TEXAS. HIGH
PRESSURE WILL BE BUILDING INTO WESTERN KANSAS BEHIND THE FRONT
THURSDAY NIGHT THROUGH FRIDAY. THE 12Z MODEL TEMPERATURE FORECASTS
ARE COMING IN COOLER THAN PREVIOUS RUNS WHICH SEEMS REASONABLE GIVEN
THE ONGOING COLD AIR ADVECTION.
INTO THIS WEEKEND, FLAT UPPER LEVEL RIDGING WILL SPREAD EAST ACROSS
THE WESTERN AND CENTRAL PART OF THE COUNTRY. ANOTHER SHORTWAVE
TROUGH WILL MOVE INTO THE PACIFIC NORTHWEST ON SATURDAY BEHIND THE
RIDGE AND THIS FEATURE WILL BE DIGGING SOME AS IT MOVES INTO THE
CENTRAL HIGH PLAINS BY MONDAY NIGHT. THROUGH THIS WEEKEND THE DRY
FORECAST WILL CONTINUE WITH TEMPERATURES WILL MODERATE BACK INTO THE
60S. LEE SIDE TROUGHING WILL DEVELOP ON SATURDAY. THIS WILL DEVELOP
INTO A LOW PRESSURE AREA THAT MOVES INTO THE OKLAHOMA AND TEXAS
PANHANDLES BY SUNDAY EVENING AS THE NEXT UPPER TROUGH APPROACHES.
THIS WILL BRING A SWITCH IN THE SURFACE WINDS BACK AROUND TO THE
EAST TO NORTHEAST ON SUNDAY. THIS WAVE WILL MOVE OUT ACROSS THE
CENTRAL AND NORTHERN PLAINS MONDAY NIGHT. THERE DOES NOT APPEAR TO
BE SUFFICIENT MOISTURE AVAILABLE FOR THIS SYSTEM TO WORK WITH. THE
BEST CHANCES FOR MEASURABLE PRECIPITATION WILL BE ALONG THE EASTERN
SLOPES OF THE ROCKIES AND OVER EASTERN KANSAS INTO THE MID
MISSISSIPPI VALLEY. HIGH TEMPERATURES WILL DROP BACK INTO THE 40S ON
MONDAY AND TUESDAY.
THE REMAINDER OF THE EXTENDED PERIOD WILL SEE AN UPPER LEVEL RIDGE
BUILDING OVER THE CENTRAL PART OF THE COUNTRY. THIS WILL RESULT IN
TEMPERATURES MODERATING BACK INTO THE 60S LATER NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1254 PM CST WED NOV 21 2012
STRONG SOUTHWEST WINDS OF 20 TO 25 KNOTS WILL CONTINUE THROUGH
SUNSET, AT WHICH POINT A DECREASE TO TO AROUND 15 KNOTS IS
EXPECTED. DURING THE OVERNIGHT HOURS...THERE WILL BE A GRADUAL
WIND SHIFT TO THE WEST THEN NORTHWEST WITH SPEEDS AROUND 6 TO 9
KNOTS. A COLD FRONT WILL MOVE ACROSS WESTERN KANSAS EARLY
THURSDAY WHICH WILL RESULT IN AN INCREASE IN WIND SPEEDS ONCE
AGAIN AFTER 15Z...TO THE 22-25 KNOT RANGE BY MIDDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 53 66 24 53 / 0 0 0 0
GCK 36 64 22 53 / 0 0 0 0
EHA 39 65 23 53 / 0 0 0 0
LBL 48 67 24 55 / 0 0 0 0
HYS 43 63 21 51 / 0 0 0 0
P28 56 72 28 53 / 10 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...UMSCHEID
SHORT TERM...UMSCHEID
LONG TERM...GERARD
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
438 PM EST WED NOV 21 2012
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 437 PM EST WED NOV 21 2012
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR RDG EXTENDING
NEWD FM THE SRN PLAINS INTO THE GRT LKS BTWN A TROF ALONG THE E
COAST AND ANOTHER ALONG THE W COAST. THE AIRMASS ALOFT IS QUITE WARM
AND DRY OVER THE UPR GRT LKS...BUT LO CLDS ENHANCED BY RADIATIONAL
COOLING LAST NGT THAT FORMED UNDER SHARP LLVL INVRN SHOWN ON LOCAL
12Z RAOBS ARE PROVING TO BE QUITE RESILIENT OVER THE SCENTRAL AND
ERN CWA WITH ADDED MOISTENING OFF LK MI IN SSW FLOW BTWN HI PRES IN
THE MID ATLANTIC AND LOWER PRES IN THE PLAINS. THERE IS NO FOG/ST
NOTED TO THE W...BUT PLENTY OF HI CLDS ARE STREAMING ENEWD FM THE
PLAINS INTO THE UPR LKS IN THE WSW FLOW ALF. A POTENT SHRTWV IS
COMING ASHORE IN THE PAC NW.
LATE THIS AFTN...LO CLDS PRESENT EARLY THIS AFTN OVER THE SCENTRAL
AND E WILL BREAK UP THRU THE AFTN IN THE PRESENCE OF SOME DIURNAL
HEATING. THESE CLDS WL BE MOST RESILIENT OVER THE FAR E DOWNWIND OF
LK MI AS STLT IMAGERY SHOWS ST DECK EXTENDING ALMOST THE ENTIRE
LENGTH OF THE LK.
TNGT...ALTHOUGH THE ST SHOULD BE GONE THIS EVNG EXCEPT OVER THE FAR
E...SUSPECT THIS LO CLD WL FORM AGAIN TNGT WITH NOCTURNAL COOLING
AND PERSISTENT SSW FLOW/LO INVRN SHOWN ON FCST SDNGS. CONFIDENCE IN
THIS SCENARIO IS HIER SINCE THE 12Z NAM/LOCAL WRF-ARW SHOW HIER
H95-9 SPECIFIC HUMIDITY ADVECTING INTO THE AREA OVERNGT IN THE
STRENGTHENING LLVL SSW FLOW. H925 WINDS AS HI AS 30-40KTS BY LATE
TNGT SHOULD LIMIT THE POTENTIAL FOR DENSER FOG...BUT STILL ADDED
SOME PATCHY FOG OVER THE SCENTRAL AND E AWAY FM MORE PRONOUNCED
DOWNSLOPE WARMING OVER THE NW AND NCENTRAL AS MODELS HINT AT A
PERIOD OF LIGHTER WINDS THIS EVNG THAT MIGHT AUGMENT A PERIOD OF
QUICK COOLING. MIN TEMPS WL REMAIN WELL ABV NORMAL WITH INCRSG
WINDS/ QUITE A BIT OF HI CLD...ESPECIALLY IN THE DOWNSLOPE AREAS
OVER THE W AND NCENTRAL NEAR LK SUP.
THANKSGIVING DAY...WITH DIURNAL HEATING...EXPECT LO CLDS/FOG IN THE
MRNG TO BREAK UP BY NOON. BUT WITH PERSISTENT SSW FLOW...THE ST WL
MOST LIKELY LINGER LONGER INTO THE AFTN OVER THE E DOWNSTREAM OF LK
MI. ATTENTION THEN TURNS TO TIMING/IMPACT OF SHRTWV NOW MOVING INTO
THE PAC NW. MODELS SHOW THIS DISTURBANCE MOVING EWD TO OVER MN BY
00Z FRI. ALTHOUGH ASSOCIATED SFC LO PRES IS FCST TO MOVE INTO
ONTARIO JUST N OF LK SUP WITH ATTENDANT COLD FNT PROGGED TO REACH
CENTRAL UPR MI BY 00Z...DEEP LARGER SCALE FORCING IS FCST TO HANG TO
THE W THRU THAT TIME. WITH LINGERING MID LVL DRY AIR...ANY
ACCOMPANYING PCPN SHOULD PUSH NO FARTHER THAN WRN LK SUP UNTIL AFT
00Z. OTRW... LOOK FOR ANOTHER DAY OF WELL ABV NORMAL TEMPS UNDER H85
THERMAL RDG UP TO 11C RIGHT AHEAD OF THE FNT. BUT TEMPS OVER THE W
SHOULD FALL IN THE AFTN FOLLOWING THE COLD FROPA WITH H85 TEMPS
PROGGED TO TUMBLE TOWARD 0C AT IWD BY 00Z FRI.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 437 PM EST WED NOV 21 2012
MODEL HAVE COME INTO MUCH BETTER OVERALL AGREEMENT RELATING TO THE
SYSTEM THAT WILL BRING SNOW TO MUCH OF THE AREA THU NIGHT INTO
SAT...WITH MAINLY SMALLER SCALE/TIMING DIFFERENCES THAT ARE NOT OUT
OF THE NORM FOR THE TIME FRAME OF THE EVENT. A GENERAL MODEL
CONSENSUS WAS USED...WITH MOST FORECAST ALIGNMENT WITH THE 12Z/21
NAM/GFS AND TO A SOMEWHAT LESSER DEGREE THE 00Z/21 ECMWF
FOCUSED MAJORITY OF ATTENTION ON THE SYSTEM THU NIGHT INTO SAT GIVEN
HIGHER IMPACTS FROM POST THANKSGIVING TRAVEL/ACTIVITIES.
AT 00Z FRI...MODELS SHOW THE 500MB SHORTWAVE IN THE BEGINNING STAGES
OF BEING CLOSED OFF OVER NW MN WITH A 1000MB SFC LOW OVER CENTRAL
LAKE SUPERIOR...AND A SFC COLD FRONT FROM THE HURON MOUNTAINS TO
IRON OR DICKINSON COUNTY. 850MB TEMPS WILL BE JUST FALLING BELOW 0C
OVER FAR WRN UPPER MI...BUT WILL STILL BY AROUND 6C OVER THE ERN
CWA. THE MID LEVEL LOW WILL CONTINUE TO STRENGTHEN AS IT MOVES TO
THE CENTRAL CWA BY 12Z FRI /AVG LOCATION AMONG PREFERRED
MODELS...THERE WERE MINOR TIMING DIFFERENCES/...WITH HEIGHT FALLS OF
7-10DAM FROM 12 HOURS PREVIOUS. BY 12Z FRI THE BULK OF THE SFC LOW
WILL HAVE SHIFTED NE INTO ONTARIO...BUT PREFER THE NAM/GEM/ECMWF
SOLUTIONS THAT PIN A 998MB SFC LOW OVER NE LAKE SUPERIOR AS OFTEN
HAPPENS DUE TO THE WARM LAKE TEMPS. 850MB TEMPS FALL TO -10C TO -12C
OVER WRN LAKE SUPERIOR BY 12Z FRI...AND WILL WELL BELOW 0C OVER THE
REST OF THE CWA. THE COMBINATION OF THE DEEPENING SFC LOW...COLD AIR
OVER THE WARM LAKE AND SHARP PRESSURE GRADIENT LEAD TO STRONG WINDS.
THE STRONGEST WINDS LOOK TO BE OVER THE KEWEENAW AND NEAR LAKE
SUPERIOR E OF THE HURON MOUNTAINS...ESPECIALLY ALONG THE SHORELINES
OF ALGER AND LUCE COUNTIES. IN THESE AREAS...MODELS SHOW 925MB WINDS
IN EXCESS OF 40KTS...SO GUSTS AS HIGH AS 40KTS SEEM APPROPRIATE FOR
THE FORECAST IN THESE MORE EXPOSED LOCATIONS FROM THE NW WINDS LATE
THU NIGHT AND THROUGH MUCH OF FRI. A SHORT SWATH OF DRY LOW AND MID
LEVEL AIR ROTATES THROUGH THE WRN CWA LATE FRI MORNING...WHICH WILL
DIMINISH SNOWFALL TO SOME EXTENT. MODELS THEN INDICATE ANOTHER
SHORTWAVE PUSHING THROUGH SOMETIME SAT EVENING AS 850MB TEMPS FALL
TO -14C OVER MUCH OF LAKE SUPERIOR...WHICH WILL ACT TO ENHANCE
SNOWFALL RATES. AFTER THIS SHORTWAVE...SNOWFALL SHOULD GENERALLY
SLOWLY DIMINISH IN INTENSITY/COVERAGE UNTIL SFC AND UPPER RIDGING
MOVES IN FROM THE W SAT...REACHING IWD BY 18Z SAT AND THE FAR ERN
CWA AROUND 00Z SUN.
GIVEN HOW QUICKLY TEMPS GET COLD AS THE UPPER LOW IS MOVING
OVER...SNOW TO LIQUID RATIOS WILL JUMP UP PRETTY QUICKLY TO AROUND
18 TO 1 RATIOS. THIS WILL INCREASE SNOWFALL ACCUMULATIONS AND WILL
ALLOW THE SNOW TO BE BLOW AROUND MORE FROM GUSTY WINDS. EXPECT TWO
MAIN BURSTS OF SNOW THAT SHOULD BE ESPECIALLY UNTACTFUL...ONE AS THE
UPPER LOW PUSHES IN WITH LAKE ENHANCEMENT ADDING TO SNOW INTENSITY.
THIS WILL HAPPEN THU NIGHT INTO EARLY FRI MORNING OVER THE WRN
CWA...AND FRI MORNING TO AROUND NOON FRI OVER THE ERN CWA. THE
SECOND BURST LOOKS TO BE WITH THE SECOND SHORTWAVE FRI EVENING TO
EARLY SAT NIGHT WITH ENHANCEMENT OF THE LES. THE FIRST BURST OF SNOW
LOOKS TO BE THE WORST GIVEN THE INCREASED FORCING FROM THE 500MB
LOW...WHICH WILL ALSO BE AT THE WORST TIMES GIVEN MUCH INCREASED
POST THANKSGIVING TRAVEL/ACTIVITY AS FAR A SOCIETAL IMPACTS GO. THIS
IS COMPOUNDED BY THE FACT THAT NO SIGNIFICANT SNOWFALL HAS OCCURRED
IN A WHILE...WHICH LOCAL STUDIES SUGGEST LEADS TO A LARGE INCREASE
IN TRAFFIC ACCIDENTS ONCE SNOW DOES FALL.
AS FAR AS SNOWFALL AMOUNTS GO...HAVE HIGHEST CONFIDENCE IN SNOWFALL
AMOUNTS OF PORTIONS OF ALGER...LUCE AND NRN SCHOOLCRAFT COUNTIES
WHERE MOISTURE WILL LINGER LONGER AND THE FETCH ACROSS LAKE SUPERIOR
WILL BE BETTER AND NW WINDS WILL NOT CHANGE DIRECTIONS MUCH THROUGH
THE EVENT. OVER THESE ERN AREAS...THE NAM SHOWS STORM TOTAL QPF
/WHICH SHOULD BE ALMOST ALL SNOW/ OF JUST UNDER 0.80 INCHES...WHICH
MAY BE A BIT ON THE HIGH SIDE BUT CAN NOT BE RULED OUT.
OVERALL...THINK 6-10 INCHES /WITH SOME POTENTIAL FOR UP TO A FOOT/
TOTAL SNOWFALL SEEMS REASONABLE FOR THE ERN AREAS. LOWEST CONFIDENCE
IS OVER THE NRN HURON MOUNTAINS IN NW MARQUETTE AND NE BARAGA
COUNTIES...AS THIS AREA IS ALWAYS HARD TO FORECAST IN NW WINDS...BUT
WOULD THINK 3-5 INCHES STORM TOTAL SNOW IS REASONABLE. THE HIGHER
TERRAIN OF WRN UPPER MI FROM IWD TO CMX AND COPPER HARBOR SHOULD SEE
4-8 INCHES STORM TOTAL SNOW /HIGHEST OVER PORTION OF NRN HOUGHTON
COUNTY AND WRN ONTONAGON/NRN GOGEBIC COUNTIES/...BUT WITH MORE
UNCERTAINTY THAT THE ERN CWA AND MORE HIGHER POSSIBILITIES OF HIGHER
OR LOWER AMOUNTS. NCENTRAL PARTS OF THE CWA /GENERALLY IN THE
MARQUETTE-NEGAUNEE AREA/ LOOK TO SEE 1-3 INCHES OF SNOW THROUGH THE
ENTIRE PERIOD. SCENTRAL PORTIONS OF THE CWA SHOULD SEE LITTLE TO NO
SNOW.
HEADLINES FOR THIS EVENT ARE SOMEWHAT TRICKY IN THAT TRADITIONAL
SNOWFALL AMOUNT BASED CRITERIA WILL NEED TO BE RELAXED GIVEN A
VARIETY OF PREVIOUSLY DISCUSSED SOCIETAL IMPACTS AND OTHER
CONTRIBUTING FACTORS /SUCH AS GUSTY WINDS/. GIVEN HIGHER CONFIDENCE
OVER THE ERN CWA /ALGER...LUCE AND NRN SCHOOLCRAFT COUNTIES/ DECIDED
TO ISSUE A WINTER STORM WATCH FOR THESE AREAS. ELSEWHERE ALONG THE
LAKE SUPERIOR SHORE...ISSUED AN SPS HIGHLIGHTING POOR TRAVEL
CONDITIONS SINCE IT IS TOO FAR OUT FOR AN ADVISORY.
NEXT SYSTEM OF INTEREST MOVES OVERHEAD ON SAT NIGHT INTO EARLY SUN
AS A CLIPPER SYSTEM PUSHES THROUGH. BEST MOISTURE IS CO-LOCATED WITH
UPPER SUPPORT IN LEFT EXIT REGION OF UPPER JET OVER NRN PORTIONS OF
THE AREA. INCREASED CONSENSUS GUIDANCE TO MID RANGE CHANCE POPS. AT
THIS TIME A COUPLE OF INCHES OF SNOW APPEARS POSSIBLE...MAINLY IN
THE HIGHER TERRAIN OVER THE NRN CWA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1226 PM EST WED NOV 21 2012
EXPECT VFR CONDITIONS TO PREDOMINATE AT ALL 3 SITES INTO THIS EVNG.
BUT WITH RADIATIONAL COOLING TNGT...EXPECT SOME FOG AND LO CLDS/IFR
CONDITIONS TO DEVELOP AT SAW. WITH INCRSG SSW WINDS OVERNGT ABOVE
RADIATION INVRN...LLWS WL DVLP AT ALL 3 LOCATIONS. DOWNSLOPE NATURE
OF THIS SSW FLOW SHOULD LIMIT THE POTENTIAL FOR LO CLDS/FOG AT CMX
AND IWD. DAYTIME HEATING/MIXING SHOULD END LLWS/DISSIPATE ANY LO
CLDS AND FOG BY LATE THU MRNG.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 437 PM EST WED NOV 21 2012
EXPECT S WINDS UP TO 20 KTS THRU THIS EVENING TO INCREASE UP TO 25
KTS LATE TONIGHT AND THU UNDER TIGHTENING PRES GRADIENT AHEAD OF
COLD FRONT ASSOCIATED WITH POWERFUL DISTURBANCE MOVING ACROSS THE
NORTHERN CONUS. ONCE THE COLD FRONT MOVES WEST TO EAST THU AFTERNOON
AND NIGHT...EXPECT A SHARP WIND SHIFT TO THE NW. AS THE PRES
GRADIENT TIGHTENS CONSIDERABLY AND MUCH COLDER AIR MOVES OVER THE
UPPER LAKES...EXPECT A HI END GALE EVENT EXCEPT OVER THE FAR W WITH
THE COLDER AIR ENHANCING THE MIXING OF STRONGER WINDS ALOFT TO THE
LAKE SURFACE. GIVEN THE CONSISTENT FORECAST TIMING AND STRENGTH OF
THIS EVENT...OPTED TO UPGRADE GOING GALE WATCHES TO WARNINGS FOR THE
LATE THU NIGHT INTO FRI NIGHT PERIOD. SOME STORM FORCE WIND GUSTS
WILL ALSO BE POSSIBLE ON FRI...ESPECIALLY OVER THE E HALF OF THE
LAKE. THE APPROACH OF A HI PRES RIDGE LATE FRI NIGHT WILL CAUSE THE
GALES TO DIMINISH W-E THEN. ANOTHER LO PRES TROF WILL IMPACT THE
UPPER GREAT LAKES OVER THE WEEKEND...BUT A WEAKER PRES GRADIENT WILL
LIKELY HOLDS WINDS TO NO HIER THAN 25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WATCH FROM LATE THURSDAY NIGHT THROUGH LATE FRIDAY
NIGHT FOR MIZ006-007-085.
LAKE SUPERIOR...
GALE WARNING FROM 1 AM FRIDAY TO 1 AM EST SATURDAY FOR
LSZ264>267.
GALE WARNING FROM 1 AM TO 7 PM EST FRIDAY FOR LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1227 PM EST WED NOV 21 2012
.UPDATE...
ISSUED AT 1052 AM EST WED NOV 21 2012
LO CLDS ARE PROVING TO BE QUITE RESILIENT OVER THE E HALF OF THE CWA
WITH SSW FLOW OFF LK MI ENHANCING THE MOISTENING UNDER SHARP LLVL
INVRN DEPICTED ON THE 12Z GRB/APX RAOBS. TENDED TO HOLD ON TO FOG
FOR A COUPLE HRS LONGER AND LOWERED MAX TEMPS A COUPLE OF DEGREES
WHERE THE ST WL LINGER LONGEST.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 608 AM EST WED NOV 21 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL RIDGE
FROM THE SOUTHERN AND CENTRAL PLAINS INTO THE WESTERN GREAT LAKES
AND A TROUGH FROM THE GULF OF ALASKA INTO THE PACIFIC NORTHWEST. A
VIGOROUS SHORTWAVE TROUGH WAS MOVING ONSHORE INTO OR AND SOUTHERN
WA. AT THE SURFACE...SOUTHERLY FLOW WAS INCREASING BETWEEN HIGH PRES
BUILDING INTO THE EASTERN GREAT LAKES AND A TROUGH FROM NW ONTARIO
INTO EASTERN NORTH DAKOTA.
WITH ABUNDANT LOW LEVEL MOISTURE OVER THE AREA...DEWPOINTS INTO THE
MID AND UPPER 30S...AREAS OF DENSE FOG HAVE DEVELOPED OVER INTERIOR
PORTIONS OF CENTRAL UPPER MICHIGAN AND OVER THE HIGHER TERRAIN OF
THE KEWEENAW. INCREASING WINDS AND DRY ADVECTION HAS HELPED REDUCE
FOG COVERAGE/DENSITY.
TODAY...EXPECT ANY LINGERING FOG TO DISSIPATE EARLY WITH THE DRY
ADVECTION FROM THE WEST AND THE ONSET OF DAYTIME HEATING LEAVING
CLEARING SKIES. WAA WILL PUSH 850 MB TEMPERATURES ARE EXPECTED TO
REACH TO AROUND 10C...HOWEVER THE WEAK NOVEMBER SUNSHINE WILL LIMIT
TEMPERATURES TO THE MID TO UPPER 50S...WITH THE WARMER TEMPERATURES
OVER THE DOWNSLOPE LOCATIONS FAVORED BY A SOUTHERLY WIND. SOUTHERLY
WINDS WILL CONTINUE TO INCREASE OVER THE REGION AS THE PRESSURE
GRADIENT INCREASES BETWEEN LOW PRESSURE APPROACHING FROM THE
NORTHWEST AND THE HIGH TO THE SOUTHEAST.
TONIGHT...LOW PRES WILL MOVE TO NORTH OF KINL KEEPING BREEZY SOUTH
WINDS GOING. SO...LOW TEMPS WILL NOT FALL OF MUCH WITH MIN READINGS
ONLY IN THE LOWER TO MID 40S. THIS COULD AGAIN RESULT IN RECORD HIGH
LOW MINS FOR MANY LOCATIONS. THE WIND AND MIXING SHOULD ALSO
MINIMIZE POTENTIAL FOR FOG FORMATION EVEN THOUGH DEWPOINTS REMAIN
AROUND 40.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 608 AM EST WED NOV 21 2012
THANKSGIVING WILL MARK THE LAST DAY OF UNSEASONABLY WARM WEATHER FOR
AWHILE AS A SW FLOW CONTINUES TO BRING WARM AIR OVER THE GREAT LAKES
REGION AHEAD OF A FAST-APPROACHING STRONG SHORTWAVE MOVING IN FM THE
NRN PLAINS. DESPITE INCREASING WAA CLOUDS IN THE AFTERNOON AHEAD OF
THE INCOMING SHORTWAVE...MIXING TO JUST 900 MB AS INDICATED ON NAM
FCST SNDGS WOULD EASILY YIELD HIGH TEMPS IN THE MID 50S ACROSS MUCH
OF THE AREA. UPPER 50S COULD EVEN BE REACHED FOR WEST HALF LOCATIONS
ALONG LAKE SUPERIOR IN DOWNSLOPE SSW FLOW. RECORD TEMP OF 54F ON THE
22ND MAY BE IN JEOPARDY AT THE MQT NWS OFFICE. TEMPS WILL STAY A BIT
COOLER (LOW 50S) ALONG LAKE MICHIGAN SHORE IN SSW FLOW. INCREASING
MID-LVL MOISTURE AND DPVA TOWARD EVENING COULD BRING IN SOME ISOLD
SHRA LATE INTO THE WESTERN CWA SO HAVE KEPT IN SLIGHT CHC
POPS.
THURSDAY NIGHT AND FRIDAY...FOLLOWED ALONG NCEP PREFERRED BLEND OF
00Z GFS AND ECMWF WHICH ADVERTISES A SLOWER AND MORE AMPLIFIED SOLN
WITH THE NRN PLAINS SHORTWAVE AND ASSOC FRONTAL SYSTEM THAN THE NAM
OR THE CANADIAN MODELS. THE GFS AND ECMWF BLENDED SOLN ALSO HAS
SUPPORT FM THE 00Z UKMET RUN. COMPROMISE SOLN WOULD TAKE
SHORTWAVE/5H CLOSED LOW ACROSS NRN WI/CENTRAL UPR MI WITH WINDS
SHIFTING FROM WEST BEHIND INITIAL COLD FROPA IN THE EVENING TO THE
NORTHWEST OVERNIGHT BEHIND PASSAGE OF MAIN SHORTWAVE/5H TROUGH AND
SECONDARY COLD FRONT. IT IS BEHIND THIS SECONDARY COLD FRONT AND
ADVECTION OF -10 TO -12C 8H AIR OVER WRN LAKE SUPERIOR THAT LAKE
EFFECT PCPN WL QUICKLY CHANGEOVER TO SNOW LATE THU NIGHT INTO EARLY
FRIDAY. THERE COULD ALSO BE SEVERAL HOUR PERIOD OF ENHANCEMENT AS
SHORTWAVE AND ASSOC DEEP LYR Q-VECT CONV SPREADS QUICKLY ACROSS THE
AREA. ENHANCEMENT WILL BE LOST BY LATE FRI AFTERNOON AS SHORTWAVE
EXITS EAST OF THE AREA AND EVENT WILL TRANSITION TO PURE LAKE EFFECT
SNOW AS 8H TEMPS LOWER TO AROUND -15C.
FRIDAY NIGHT INTO SATURDAY...THERE MAY BE A BRIEF PERIOD FOR
ADDITIONAL ENHANCEMENT TO SNOW FRI EVENING WITH MODELS HINTING AT
ANOTHER WEAK CLIPPER SHORTWAVE MOVING ACROSS THE AREA BUT AFTER THAT
MODELS ARE IN GOOD AGREEMENT WITH STRONG RDG BUILDING IN FM NW OF
LAKE SUPERIOR. STRONG SUBSIDENCE ASSOC WITH THIS RDG WILL SHARPLY
LOWER INVERSION HGTS TO BLO 4KFT OVER THE WEST BY 12Z SAT WHICH
SHOULD QUICKLY DIMINISH LES TO FLURRIES EARLY SATURDAY. LONGER FETCH
IN NW FLOW ACROSS ERN LAKE SUPERIOR WILL ALLOW SOME LES TO
ACCUMULATE INTO SAT MORNING BUT THEN STRONG SUBSIDENCE AND DRYING
SHOULD DIMINISH ANY REMAINING LES TO FLURRIES BY AFTERNOON.
TOTAL SNOW ACCUMULATION DURING THE EVENT FM THU NIGHT INTO EARLY
SATURDAY WILL LIKELY REACH 3-7 INCHES WITH THE HIGHEST AMOUNTS OVER
HIGHER NW FACING TERRAIN OF WRN AND ERN SECTIONS OF THE CWA DOWNWIND
OF LAKE SUPERIOR. AN ADVISORY HEADLINE MAY EVENTUALLY BE NEEDED
DURING THIS TIME FRAME BUT FOR NOW WILL CONTINUE WORDING OF SEVERAL
INCHES OF ACCUMULATING SNOW IN THE HWO.
SUNDAY THROUGH TUESDAY...MODELS IN GENERAL AGREEMENT WITH A
TRANSITION TOWARD A MORE ZONAL FLOW PATTERN FOR EARLY NEXT WEEK. A
WEAK WNW FLOW SHORTWAVE MOVING THROUGH SAT NIGHT INTO SUNDAY COULD
BRING SOME LIGHT SNOW TO MAINLY THE NRN AND ERN PORTIONS OF THE CWA.
A WEAK N-NE FLOW SETTING UP FOR MON INTO TUE BTWN HIGH PRESSURE OVER
SCNTRL CANADA/NRN PLAINS AND LOW PRESSURE DVLPG OVER THE SRN/CENTRAL
PLAINS WILL CONTINUE TO WARRANT LOW CHC POPS FOR LIGHT LES WITH 8H
TEMPS LINGERING AROUND -14C.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1226 PM EST WED NOV 21 2012
EXPECT VFR CONDITIONS TO PREDOMINATE AT ALL 3 SITES INTO THIS EVNG.
BUT WITH RADIATIONAL COOLING TNGT...EXPECT SOME FOG AND LO CLDS/IFR
CONDITIONS TO DEVELOP AT SAW. WITH INCRSG SSW WINDS OVERNGT ABOVE
RADIATION INVRN...LLWS WL DVLP AT ALL 3 LOCATIONS. DOWNSLOPE NATURE
OF THIS SSW FLOW SHOULD LIMIT THE POTENTIAL FOR LO CLDS/FOG AT CMX
AND IWD. DAYTIME HEATING/MIXING SHOULD END LLWS/DISSIPATE ANY LO
CLDS AND FOG BY LATE THU MRNG.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 608 AM EST WED NOV 21 2012
WINDS SHOULD REMAIN BELOW 20 KNOTS THROUGH THURSDAY MORNING AS HIGH
PRESSURE REMAINS IN CONTROL OF THE REGION. WINDS WILL SHIFT FROM THE
SOUTH THURSDAY AFTERNOON TO THE NORTHWEST AND INCREASE TO GALES TO
35 KNOTS BY FRIDAY MORNING AS THE PRESSURE GRADIENT INCREASES ACROSS
THE AREA. GALES ARE ARE EXPECTED TO DIMINISH BY FRIDAY EVENING OVER
WESTERN LAKE SUPERIOR AND OVER THE EAST LATE FRIDAY NIGHT. WINDS
SHOULD REMAIN BELOW 20 KNOTS FROM SATURDAY AFTERNOON THROUGH THE
REMAINDER OF THE PERIOD.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WATCH FROM LATE THURSDAY NIGHT THROUGH LATE FRIDAY NIGHT
FOR LSZ264>267.
GALE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY EVENING FOR
LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KC
SHORT TERM...JLB
LONG TERM...VOSS
AVIATION...KC
MARINE...JLB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1256 PM EST WED NOV 21 2012
.SYNOPSIS...
HIGH PRESSURE REMAINS OVER THE REGION THROUGH THE THANKSGIVING
HOLIDAY. A COLD FRONT MOVES THROUGH FRIDAY NIGHT. WHILE THE COLD
FRONT WILL MOVE THROUGH THE AREA DRY...THE FRONT WILL PROVIDE FOR
NOTICEABLY COLDER AND BREEZY CONDITIONS SATURDAY.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 950 AM WEDNESDAY...
AS THE SHORTWAVE TROUGH ALOFT OVER THE SOUTHEAST CONTINUES TO DIG
SOUTHEAST...THE PATCHY CLOUDS ASSOCIATED WITH THE WAVE...MAINLY
OVER THE SOUTHWEST PIEDMONT INTO SOUTH CAROLINA...HAVE ALSO MOVED
SOUTHEAST AND ERODED SOMEWHAT WITH TIME ON SATELLITE IMAGERY. THE
LATEST NAM AND RUC GUIDANCE ARE FAIRLY SIMILAR IN SHOWING SOME
UPPER-LEVEL MOISTURE ESPECIALLY TOWARD KFAY INTO THIS AFTERNOON...
WITH DRYING EVEN IN THE UPPER LEVELS THERE DURING THE AFTERNOON.
PATCHY LOW CLOUDS WERE ERODING AS WELL...AND WITH A DRY AND STABLE
OVERALL AIR MASS...ANTICIPATE CONSIDERABLE SUNSHINE WITH MOSTLY
SCATTERED CLOUDS MOVING EAST FROM THE SOUTHWEST PIEDMONT ACROSS THE
SANDHILLS. AREAS ALONG AND SOUTH OF A LINE FROM ABOUT KAFP TO KCTZ
INCLUDING KFAY COULD HAVE A PERIOD OF BROKEN MID-LEVEL CLOUDS...BUT
THE DAY SHOULD STILL AVERAGE MOSTLY SUNNY. MORNING 1000-850MB
THICKNESSES WHEN COMBINED WITH ANTICIPATED VALUES IN THE AFTERNOON
CORRESPOND WELL WITH MOS GUIDANCE AND ONGOING HIGHS...AND ALTHOUGH
MIXING WILL STRUGGLE TO REACH TO 850MB...GIVEN THE BETTER INSOLATION
OF TODAY AS COMPARED TO TUESDAY...WILL ANTICIPATE SIMILAR HIGHS...
AROUND 60. THERE WILL BE SOME WIND GUSTS IN THE TEENS KNOTS...
HIGHEST TOWARD INTERSTATE 95 WHERE ALREADY KCTZ NOTED A GUST IN THE
UPPER TEENS KNOTS JUST AFTER 1430Z. THIS WOULD BE ABOUT THE MAXIMUM
GUST ANTICIPATED BASED ON THE CONSENSUS OF THE LATEST GFS AND NAM
BUFR SOUNDINGS. -DJF
TONIGHT...RIDGING AND HEIGHT RISES ALOFT IN THE WAKE OF THE TROUGH
AXIS WILL YIELD CLEAR AND ASSOCIATED CHILLY CONDITIONS TONIGHT.
PERSISTENCE LOWS IN THE LOWER 30S TO NEAR 40 DEGREES...HIGHEST
AMIDST NORTHERLY STIRRING WITHIN THE TIGHTEST PRESSURE GRADIENT OVER
THE COASTAL PLAIN.
THANKSGIVING DAY...CONTINUED RIDGING AND HEIGHT RISES ALOFT AND
ASSOCIATED SUBSIDENCE WILL YIELD SUNNY AND CONTINUED MILD WEATHER
FOR THANKSGIVING...WITH HIGH TEMPERATURES AGAIN IN THE UPPER 50S TO
LOWER 60S. FURTHER DEEPENING OF THE WESTERN ATLANTIC LOW AND...AN
ASSOCIATED CONTINUED RELATIVE MAXIMUM IN THE PRESSURE GRADIENT OVER
EASTERN NC...WILL RESULT IN A NOTICEABLE NNE 10-15 MPH BREEZE AGAIN
WITH GUSTS TO NEAR 20 MPH INVOF AND ESPECIALLY EAST OF I-95...WITH
LIGHTER WIND TO THE WEST.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 130 AM WEDNESDAY...
HIGH PRESSURE IN PLACE TO START THE PERIOD DAMPENS QUICKLY ON FRIDAY
AS A LOW PRESSURE SYSTEM AND ASSOCIATED SURFACE COLD FRONT APPROACH
THE AREA. ALTHOUGH WARM AIR WILL BE ADVECTING INTO CENTRAL NC OUT
AHEAD OF THE FRONT...ITS SOURCE IS A DRY CONTINENTAL AIRMASS WITHOUT
MUCH MOISTURE ADVECTION FROM THE GULF. THE GFS CONTINUES TO SHOW
WESTERLY FLOW ABOVE THE BOUNDARY LAYER WEST OF THE MTNS...WHICH
SUPPORTS DOWNSLOPE FLOW. THUS...EXPECT A DRY FRONTAL PASSAGE FRIDAY
AFTERNOON. GIVEN THE MOISTURE IN THE UPPER LEVELS THERE WILL LIKELY
BE HIGH CLOUDS OUT AHEAD OF THE FRONT AND WITH THE MOISTURE
CONVERGENCE ALONG THE FRONT...EXPECT A LAYER OF CLOUDS NEAR 850 MB
ALONG THE FRONT WITH DRYING FROM THE TOP DOWN BEHIND IT. LOW TEMPS
THURSDAY NIGHT IN THE MID TO UPPER 30S. WITH THE WARM ADVECTION
AHEAD OF THE FRONT HAVE HIGHS IN THE MID 60S FRIDAY...AND WITH
CURRENT TIMING OF THE FRONT EXPECT FRIDAY NIGHT LOWS IN THE MID 30S
NW TO LOW 40S SE.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 255 AM WEDNESDAY...
SATURDAY THROUGH MONDAY:
SKIES WILL CONTINUE CLEARING FROM NW TO SE ON SATURDAY AS THE COLD
FRONT PUSHES OFFSHORE. FORECAST 1000-850 MB THICKNESS VALUES
DECREASE BY APPROX 70 METERS FROM 00Z SATURDAY TO 00Z SUNDAY. WHILE
THIS IS LIKELY A LITTLE OVER DONE AND MAY NOT ACCOUNT FOR THE
ADIABATIC WARMING WITH THE STRONG NW WINDS OFF THE MTNS BEHIND THE
FRONT ON SATURDAY...TEMPS WILL STILL BE SIGNIFICANTLY COLDER THAN
FRIDAY...WITH HIGHS IN THE UPPER 40S NW TO MID 50S SE AND OVERNIGHT
LOWS IN THE UPPER 20S TO LOW 30S. AS SURFACE HIGH PRESSURE BUILDS
INTO THE AREA OVERNIGHT...THE MAIN UPPER LEVEL TROUGH AXIS WILL
SHIFT OFFSHORE. AS THE HIGH MOVES OVER CENTRAL NC AND OFF THE NC
COAST SUNDAY NIGHT...WINDS SPEEDS WILL DECREASE AT THE SURFACE AND
ALOFT WHILE SURFACE WINDS SHIFT FROM NW TO SW. WILL CONTINUE TO HAVE
WEST TO NORTHWEST WINDS ABOVE THE BOUNDARY LAYER WITH GOOD
SUBSIDENCE AND ADIABATIC WARMING...YIELDING A STRONG SUBSIDENCE
INVERSION AT THE TOP OF THE MIXED LAYER. LOW LEVEL THICKNESSES WILL
RECOVER SOME IN THE NW ON SUNDAY RESULTING IN TEMPS A COUPLE DEGREES
WARMER...LOW 50S... WHILE HIGHS ELSEWHERE WILL BE ABOUT THE SAME TO
A LITTLE COOLER THAN SATURDAY...LOW TO MID 50S. ALTHOUGH THE LOW
LEVEL THICKNESSES GRADUALLY INCREASE ACROSS THE AREA SUNDAY
NIGHT...CLEAR SKIES AND LIGHT WINDS NEAR THE SURFACE UNDER THE HIGH
WILL YIELD OVERNIGHT LOWS ONLY SLIGHTLY WARMER IN THE NW TO SIMILAR
TO THE PREVIOUS NIGHT ACROSS THE SE...MAINLY IN THE LOW 30S. IN
ADDITION TO THE INCREASING THICKNESSES...RELATIVELY WARM AIR WILL
BEGIN ADVECTING INTO CENTRAL NC FROM THE SSW ON MONDAY. AS SKIES
WILL REMAIN CLEAR TO PARTLY CLOUDY FOR MUCH OF THE DAY EXPECT HIGHS
IN THE MID 50S TO NEAR 60.
MONDAY NIGHT AND TUESDAY:
SURFACE LOW OVER THE TX PANHANDLE 00Z TUESDAY WILL MOVE EAST AND
THEN NE OVER THE MS RIVER VALLEY BY DAYBREAK TUESDAY. WILL SEE
INCREASING HIGH CLOUDS BEGINNING MONDAY EVENING. THIS LOW PRESSURE
SYSTEM WILL HAVE GOOD MOISTURE FEED INTO IT FROM THE GULF OF MEXICO
AS IT MOVES EASTWARD. AS THE WARM MOIST AIR ADVECTS INTO THE AREA ON
TUESDAY SKIES WILL QUICKLY BECOME OVERCAST AND AS THE TROUGH
APPROACHES SSW SURFACE WINDS WILL INCREASE. AS OF THE MOST RECENT
MODEL RUNS...COULD SEE PRECIP REACHING THE WESTERN PARTS OF OUR AREA
AROUND 18Z AND PROGRESSING EASTWARD THROUGH THE END OF THE PERIOD.
AS SUCH...WILL CARRY A SLIGHT CHANCE OF PRECIP ACROSS THE NW PRIOR
TO 12Z TUESDAY...INCREASING TO CHANCE IN THE NW TO SLIGHT CHANCE IN
THE SE BY 00Z WEDNESDAY. EXPECT MONDAY NIGHT LOWS IN THE UPPER 30S
TO LOW 40S WITH HIGHS ON TUESDAY IN THE MID 50S NW TO LOW 60S SE.
HOWEVER...TEMPS ON TUESDAY MAY CHANGE IF CHANGES IN TIMING OF PRECIP
OCCUR. GIVEN THAT THIS SYSTEM IS COMING IN AT THE END OF THE
FORECAST PERIOD AND THERE ARE STILL SOME DIFFERENCES IN TIMING
BETWEEN THE MODELS...CONFIDENCE IN EITHER PARAMETER IS NOT
PARTICULARLY HIGH AT THIS POINT IN TIME.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 1255 PM WEDNESDAY...
VFR CONDITIONS WILL PERSIST THROUGH THE 18Z VALID TAF PERIOD. A FEW
NORTH TO NORTHEAST WIND GUSTS IN THE TEENS KNOTS WILL CONTINUE
THROUGH MID-AFTERNOON...AND MORE OF THE SAME WITH GUSTS A COUPLE OF
KNOTS HIGHER WILL OCCUR THURSDAY. LIGHTEST WINDS WILL BE TOWARD THE
TRIAD THIS AFTERNOON THROUGH THURSDAY. OVERNIGHT...AVIATION
INTERESTS SHOULD BE PREPARED FOR NORTH-TO-NORTHEAST WINDS INCREASING
TO BETWEEN 25 AND 30KT BY 2000FT. GIVEN THE EXPECTED AVERAGE SURFACE
WIND...LOW-LEVEL WIND SHEAR WAS ON THE LOW MARGINS AND WAS NOT
INCLUDED IN THE 18Z VALID TAF FOR LOCATIONS LIKE KFAY AND KRWI...
WHERE WINDS NEAR 2000FT AND JUST ABOVE SHOULD BE THE HIGHEST IN
CENTRAL NORTH CAROLINA OVERNIGHT.
BEYOND THE 18Z VALID TAF PERIOD...A DRY COLD FRONT MOVES THROUGH
FRIDAY NIGHT. UNDER VFR CONDITIONS...A NORTHWEST WIND GUSTING TO THE
MID TO UPPER 20S KNOTS CAN BE EXPECTED SATURDAY. THE NEXT THREAT
FOR SUB-VFR CONDITIONS...DEPENDING ON THE AMOUNT OF MOISTURE RETURN
INTO CENTRAL NORTH CAROLINA ON AN INCREASING SOUTHWEST FLOW...WILL
BE LATE MONDAY NIGHT.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DJF
NEAR TERM...DJF/MWS
SHORT TERM...KC
LONG TERM...KC
AVIATION...DJF
AREA FORECAST DISCUSSION
NWS AMARILLO TX
415 PM CST WED NOV 21 2012
.DISCUSSION...
CONTINUED DRY CONDITIONS AND PERIODIC FRONTAL PASSAGES HIGHLIGHT THE
FORECAST PERIOD.
SOUTHWESTERLY WINDS AND CLOUD COVER HAVE INCREASED TODAY IN ADVANCE
OF A SHORTWAVE TROUGH NOW EJECTING THROUGH THE AMBIENT SOUTHWESTERLY
FLOW ALOFT. WHILE MOST OF THE FORCING/ASCENT AND MEANINGFUL RAIN
CHANCES ASSOCIATED WITH THIS FEATURE WILL REMAIN WELL SOUTH OF THE
AREA...SOME ENHANCED VORTICITY/DEEPENING OF THE TROUGH HAS EMERGED THIS
AFTERNOON OVER CENTRAL NEW MEXICO. ISOLATED HIGH-BASED CONVECTION HAS
DEVELOPED NEAR ROSWELL. ALL NWP SOLUTIONS MINIMIZE PROSPECTS FOR
PRECIPITATION IN THE PANHANDLES AS THIS TRANSLATES OVER THE REGION
TONIGHT. ONLY THE RAP DEPICTS THE SMALLEST HINT OF QPF OVER THE
SOUTHWESTERN PANHANDLE. THUS WE HAVE MAINTAINED A DRY FORECAST WITH
GRIDDED POPS AT/BELOW 10 PERCENT.
A FRONT IS EXPECTED TO PUSH ACROSS THE PANHANDLES AFTER 12-15Z
THURSDAY IN WAKE OF THE PASSING SHORTWAVE TROUGH AXIS. 3-HR PRESSURE
RISES AROUND 4 MB OVER KANSAS WILL SUPPORT POST FRONTAL WINDS OF 15
TO 25 MPH...ESPECIALLY OVER THE OKLAHOMA PANHANDLE AND THE NORTHERN
TEXAS PANHANDLE. ALL INDICATIONS OF SUFFICIENT LIFT/MOISTURE TO
SUPPORT CONVECTION ALONG THE FRONT ARE DISPLACED WELL EAST AND SOUTH
OF THE REGION.
A 1035-1037 MB CONTINENTAL SURFACE HIGH WILL PUSH SOUTHWARD THROUGH
THE PLAINS IN WAKE OF THE FRONT. THIS WILL RESULT IN NOTABLY COOLER
TEMPERATURES /SOME 5 DEGREES BELOW SEASONAL AVERAGES/ BY FRIDAY. THE
COOL SURFACE RIDGE WILL TRANSLATE SOUTHEAST TOWARD THE LOWER
MISSISSIPPI VALLEY...LENDING TOWARD TEMPERATURE MODERATION OVER THE
PANHANDLES THROUGH THE WEEKEND. THIS AS LOW AMPLITUDE RIDGING OVER
THE WEST RESULTS IN MODEST NORTHWESTERLY FLOW OVER THE CENTRAL/SOUTHERN
PLAINS AND LEE TROUGHING.
ATTENTION THEN SHIFTS TOWARD A SHORTWAVE TROUGH AND ASSOCIATED FRONTAL
PASSAGE EARLY NEXT WEEK. THE INITIAL FRONTAL PASSAGE WILL OCCUR DURING
THE LATE SUNDAY/EARLY MONDAY TIMEFRAME...AND MAY RESULT IN PROBLEMATIC
TEMPERATURE FORECASTS INITIALLY. THE FRONT WILL FINALLY PUSH SOLIDLY
THROUGH BY LATE MONDAY AS THE APPROACHING SHORTWAVE TROUGH AMPLIFIES
IN NORTHWESTERLY FLOW. SOME SOLUTIONS GENERATE LIGHT QPF IN PROXIMITY
TO THE NORTHERN AND EASTERN PANHANDLES...BUT CONFIDENCE IN SUFFICIENT
FORCING/MOISTURE IS NOT HIGH AND THE CURRENT DRY FORECAST CONTINUES TO
APPEAR VALID.
&&
.FIRE WEATHER...
ONGOING ELEVATED FIRE WEATHER OVER THE WESTERN AND CENTRAL OKLAHOMA
PANHANDLE AND NORTHWESTERN TEXAS PANHANDLE WILL DIMINISH BY EARLY
EVENING. CONCERNS FOR ELEVATED CONDITIONS WILL AGAIN EXIST THURSDAY...
AS POST FRONTAL WINDS INCREASE INTO THE 15 TO 20 MPH RANGE AND AFTERNOON
HUMIDITY MINIMA DROP TOWARDS 15 PERCENT AGAIN OVER THE WESTERN OKLAHOMA
PANHANDLE AND THE NORTHWESTERN TEXAS PANHANDLE. OTHERWISE...ELEVATED
OR CRITICAL CONDITIONS ARE NOT ANTICIPATED THROUGH THE REMAINDER OF THE
PERIOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMARILLO TX 46 68 30 53 27 / 5 0 0 0 0
BEAVER OK 47 63 27 52 26 / 5 0 0 0 0
BOISE CITY OK 39 64 24 51 27 / 5 0 0 0 0
BORGER TX 48 67 33 54 31 / 5 0 0 0 0
BOYS RANCH TX 44 65 29 53 26 / 5 0 0 0 0
CANYON TX 46 69 29 53 27 / 10 0 0 0 0
CLARENDON TX 50 73 34 55 30 / 5 5 0 0 0
DALHART TX 35 64 23 52 23 / 5 0 0 0 0
GUYMON OK 42 66 25 55 26 / 5 0 0 0 0
HEREFORD TX 45 71 28 55 26 / 10 0 0 0 0
LIPSCOMB TX 51 68 30 54 27 / 5 0 0 0 0
PAMPA TX 48 66 31 52 29 / 5 0 0 0 0
SHAMROCK TX 52 75 35 57 31 / 5 5 5 0 0
WELLINGTON TX 52 78 37 58 32 / 5 5 5 0 0
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
15/10