Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/13/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1036 AM MST FRI JAN 11 2013
.UPDATE...A COMPACT SURFACE LOW HAS FORMED OVER THE NORTHEAST
PLAINS CAUSING DOWNSLOPING WINDS ALONG THE FOOTHILLS AND NORTHERLY
WINDS OVER THE I-25 CORRIDOR FROM KCYS DOWN TO KDEN. AN AREA OF
SNOW RELATED TO THE DYNAMIC FORCING ALOFT HAS MOVED OUT OVER FORT
COLLINS AND GREELEY. WITH THE SUPPORT OF THE NORTHERLY SURFACE
WINDS...WE COULD SEE THIS AREA OF SNOW PERSIST THROUGH THE
AFTERNOON ON THE NORTHWEST SIDE OF THE SURFACE LOW. WILL UPDATE
THE FORECAST TO INCREASE THE CHANCE OF SNOW ACROSS THE PLAINS
THROUGH THIS AFTERNOON AND EVENING. WILL ALSO ADD SOME FOG AND
FREEZING DRIZZLE TO THE NORTHEAST CORNER OF THE STATE WHERE
MOISTURE AT THE SURFACE HAS MOVED IN FROM NEBRASKA. AS THE SURFACE
LOW MOVES INTO NEBRASKA THIS AFTERNOON THE FREEZING DRIZZLE WILL
BE REPLACED BY LIGHT SNOW. COLD TEMPERATURES ARE ON THEIR WAY AS
NORTHERLY FLOW ACROSS THE PLAINS INCREASES THROUGH THIS EVENING.
THE REST OF THE FORECAST LOOKS OKAY FOR NOW.
&&
.AVIATION...LOOKS LIKE WINDS WILL BE TRANSITIONING TO NORTHWEST
AND MAYBE NORTHERLY THIS EVENING IN THE WRAP-AROUND TO THE WEST OF
THE SURFACE LOW. WILL INCREASE THE MENTION OF LIGHT SNOW AT DENVER
AREA AIRPORTS THROUGH THE AFTERNOON. CEILINGS WILL DROP INTO MVFR
RANGE...BUT SOME DOWNSLOPE DRYING OFF THE MOUNTAINS SHOULD KEEP
IFR CEILINGS FROM DEVELOPING.
&&
.PREV DISCUSSION... /ISSUED 426 AM MST FRI JAN 11 2013/
SHORT TERM...LATEST RAP QG ANALYSIS SHOWS THE BEST LIFT OVER
CENTRAL COLORADO AT 09Z. ALL OF THE MODELS TAKE THIS OFF TO THE
NORTHEAST DURING THE DAY WITH DECENT SUBSIDENCE MOVING OVERHEAD IN
ITS WAKE. SURFACE CYCLONE IS LOCATED OVER NORTHEAST COLORADO AND
THIS FEATURE IS SCHEDULED TO BOOK OFF TO THE NORTHEAST QUITE
QUICKLY LATER TODAY. PRECIPITATION IS EITHER UNDERWAY AT THIS HOUR
OR WILL SOON BE IN MUCH OF THE HIGH COUNTRY WITH A SEVERAL-HOUR-
LONG BURST OF SNOW EXPECTED DURING THE MORNING HOURS ALONG WITH
SOME BLOWING SNOW. SYNOPTICALLY DRIVEN HIGH COUNTRY SNOW WILL GIVE
WAY TO BETTER OROGRAPHICALLY DRIVEN SNOW AFTER THE TROUGH PASSES.
ADVISORY FOR ZONE 31 LOOKS GOOD FOR THIS. SNOW SHOWERS SHOULD
LINGER THROUGHOUT THE NIGHT AS COLDER AIR FILTERS IN. THE PLAINS
WILL HAVE A SMALL THREAT OF PRECIPITATION AS THE UPPER TROUGH
PASSES BUT THE POSITION OF THE SURFACE CYCLONE AND ITS ATTENDANT
DOWNSLOPE IS NOT IDEAL FOR PLAINS PRECIPITION. AS THIS FEATURE
PULLS TO THE NORTHEAST OVERNIGHT THE FLOW WILL START TO TURN TO
MORE UPSLOPE...BRINGING COLD AIR UP AGAINST THE MOUNTAINS.
MOISTURE SEEMS A BIT SCANT IN THE MODELS BUT THERE WILL PROBABLY
BE ENOUGH AROUND FOR AT LEAST SOME LOWER CLOUDINESS. EVERYONE IS
GOING TO GET COLD TONIGHT WITH SINGLE DIGITS ACROSS THE PLAINS AND
SUBZERO READINGS IN THE HIGH COUNTRY.
LONG TERM...THE UPPER LEVEL TROUGH AXIS OVER WY...UT AND WESTERN
AZ SATURDAY MORNING WILL MOVE EAST THROUGH THE DAY PASSING OVER
THE STATE. SLIGHTLY COLDER TEMPERATURES WILL FILTER IN THROUGH THE
DAY AND WEAK UPWARD QG VERTICAL VELOCITY WILL PASS OVERHEAD. SOME
MOISTURE WILL STILL BE AVAILABLE TO CONTINUE LIGHT SNOW OVER THE
HIGH MOUNTAINS WITH ANOTHER 2 TO 4 INCHES...WITH THE HIGHEST
AMOUNTS OVER WESTERN JACKSON AND GRAND COUNTIES. A SURFACE HIGH
OVER THE NORTHERN PLAINS WILL BE PUSHING SOUTH TO PRODUCE UPSLOPE
FLOW OVER THE PLAINS WHICH WILL COMBINE WITH THE EXTRA LIFT AND
MOISTURE FOR A SLIGHT CHANCE OF LIGHT SNOW OVER THE URBAN
CORRIDOR DURING SATURDAY AFTERNOON. TEMPERATURES WILL BE IN THE
SINGLE DIGITS IN THE MOUNTAINS AND IN THE TEENS FOR THE PLAINS FOR
HIGHS...THEN BECOME -10 TO -25 IN THE MOUNTAINS AND SINGLE DIGITS
TO BELOW ZERO FOR THE PLAINS SATURDAY NIGHT.
THE AIRMASS WILL BEGIN DRYING OUT BUT REMAINING COLD AS THE
ANOTHER PIECE OF ENERGY MOVING INTO THE UPPER TROUGH FINALLY
BEGINS TO HELP MOVE THE TROUGH OUT OF THE AREA BY MONDAY. THE WELL
BELOW AVERAGE TEMPERATURES WILL HANG AROUND SUNDAY WITH LITTLE TO
NO SNOW EXPECTED FOR THE HIGH COUNTRY.
NORTH TO NORTHEAST FLOW ALOFT WILL TURN NORTH TO NORTHEAST MONDAY
NIGHT THROUGH TUESDAY. TEMPERATURES WILL BE WARMING SLOWLY WITH
SURFACE GRADIENTS TIGHTENING TUESDAY NIGHT AS A LOW MOVES DOWN THE
LEE SIDE OF THE ROCKIES AS HIGH PRESSURE RESIDES OVER THE GREAT
BASIN. THE RESULTING WESTERLY WINDS WILL MOST LIKELY HELP SCOUR
OUT THE COLD AIRMASS. COULD SEE A FEW SNOW SHOWERS OVER THE HIGH
COUNTRY TUESDAY.
WEDNESDAY AND THURSDAY WILL BE IN DRY WEST TO NORTHWESTERLY ZONAL
FLOW WITH NEAR NORMAL TEMPERATURES. THE PRECIPITATION FORECAST
LOOKS GRIM IN THIS FLOW AS THE CLOSEST AREA OF MOISTURE OVER THE
NORTHERN STATES LOOKS LIKE IT WILL KEEP TO THE NORTH.
AVIATION...WARM SOUTH TO SOUTHWEST SURFACE WINDS EARLY THIS
MORNING WILL GRADUALLY VEER AROUND TO WESTERLY AND INCREASE IN
SPEED AND GUSTINESS AS BORA CONDITIONS DEVELOP BEHIND THE TROUGH
PASSAGE BY LATER THIS MORNING. GUSTY WESTERLIES CAN BE EXPECTED
THROUGHOUT THE LATER MORNING AND AFTERNOON BEFORE TURNING TO NORTH
AND THEN EAST AND DECREASING OVERNIGHT. WITH A SMALL THREAT OF
SHOWER ACTIVITY LOWER CEILINGS AND BRIEF LOWERED VISIBILITIES ARE
A SMALL POSSIBILITY...MAINLY THIS MORNING. SOME STRATUS MAY BE
AROUND LATER TONIGHT BUT IFR CONDITIONS ARE NOT EXPECTED AT THIS
TIME.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 5 AM MST SATURDAY FOR COZ031.
&&
$$
SHORT TERM...DANKERS
LONG TERM....99
AVIATION...DANKERS
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
426 AM MST FRI JAN 11 2013
.SHORT TERM...LATEST RAP QG ANALYSIS SHOWS THE BEST LIFT OVER
CENTRAL COLORADO AT 09Z. ALL OF THE MODELS TAKE THIS OFF TO THE
NORTHEAST DURING THE DAY WITH DECENT SUBSIDENCE MOVING OVERHEAD IN
ITS WAKE. SURFACE CYCLONE IS LOCATED OVER NORTHEAST COLORADO AND
THIS FEATURE IS SCHEDULED TO BOOK OFF TO THE NORTHEAST QUITE
QUICKLY LATER TODAY. PRECIPITATION IS EITHER UNDERWAY AT THIS HOUR
OR WILL SOON BE IN MUCH OF THE HIGH COUNTRY WITH A SEVERAL-HOUR-
LONG BURST OF SNOW EXPECTED DURING THE MORNING HOURS ALONG WITH
SOME BLOWING SNOW. SYNOPTICALLY DRIVEN HIGH COUNTRY SNOW WILL GIVE
WAY TO BETTER OROGRAPHICALLY DRIVEN SNOW AFTER THE TROUGH PASSES.
ADVISORY FOR ZONE 31 LOOKS GOOD FOR THIS. SNOW SHOWERS SHOULD
LINGER THROUGHOUT THE NIGHT AS COLDER AIR FILTERS IN. THE PLAINS
WILL HAVE A SMALL THREAT OF PRECIPITATION AS THE UPPER TROUGH
PASSES BUT THE POSITION OF THE SURFACE CYCLONE AND ITS ATTENDANT
DOWNSLOPE IS NOT IDEAL FOR PLAINS PRECIPITION. AS THIS FEATURE
PULLS TO THE NORTHEAST OVERNIGHT THE FLOW WILL START TO TURN TO
MORE UPSLOPE...BRINGING COLD AIR UP AGAINST THE MOUNTAINS.
MOISTURE SEEMS A BIT SCANT IN THE MODELS BUT THERE WILL PROBABLY
BE ENOUGH AROUND FOR AT LEAST SOME LOWER CLOUDINESS. EVERYONE IS
GOING TO GET COLD TONIGHT WITH SINGLE DIGITS ACROSS THE PLAINS AND
SUBZERO READINGS IN THE HIGH COUNTRY.
.LONG TERM...THE UPPER LEVEL TROUGH AXIS OVER WY...UT AND WESTERN
AZ SATURDAY MORNING WILL MOVE EAST THROUGH THE DAY PASSING OVER
THE STATE. SLIGHTLY COLDER TEMPERATURES WILL FILTER IN THROUGH THE
DAY AND WEAK UPWARD QG VERTICAL VELOCITY WILL PASS OVERHEAD. SOME
MOISTURE WILL STILL BE AVAILABLE TO CONTINUE LIGHT SNOW OVER THE
HIGH MOUNTAINS WITH ANOTHER 2 TO 4 INCHES...WITH THE HIGHEST
AMOUNTS OVER WESTERN JACKSON AND GRAND COUNTIES. A SURFACE HIGH
OVER THE NORTHERN PLAINS WILL BE PUSHING SOUTH TO PRODUCE UPSLOPE
FLOW OVER THE PLAINS WHICH WILL COMBINE WITH THE EXTRA LIFT AND
MOISTURE FOR A SLIGHT CHANCE OF LIGHT SNOW OVER THE URBAN
CORRIDOR DURING SATURDAY AFTERNOON. TEMPERATURES WILL BE IN THE
SINGLE DIGITS IN THE MOUNTAINS AND IN THE TEENS FOR THE PLAINS FOR
HIGHS...THEN BECOME -10 TO -25 IN THE MOUNTAINS AND SINGLE DIGITS
TO BELOW ZERO FOR THE PLAINS SATURDAY NIGHT.
THE AIRMASS WILL BEGIN DRYING OUT BUT REMAINING COLD AS THE
ANOTHER PIECE OF ENERGY MOVING INTO THE UPPER TROUGH FINALLY
BEGINS TO HELP MOVE THE TROUGH OUT OF THE AREA BY MONDAY. THE WELL
BELOW AVERAGE TEMPERATURES WILL HANG AROUND SUNDAY WITH LITTLE TO
NO SNOW EXPECTED FOR THE HIGH COUNTRY.
NORTH TO NORTHEAST FLOW ALOFT WILL TURN NORTH TO NORTHEAST MONDAY
NIGHT THROUGH TUESDAY. TEMPERATURES WILL BE WARMING SLOWLY WITH
SURFACE GRADIENTS TIGHTENING TUESDAY NIGHT AS A LOW MOVES DOWN THE
LEE SIDE OF THE ROCKIES AS HIGH PRESSURE RESIDES OVER THE GREAT
BASIN. THE RESULTING WESTERLY WINDS WILL MOST LIKELY HELP SCOUR
OUT THE COLD AIRMASS. COULD SEE A FEW SNOW SHOWERS OVER THE HIGH
COUNTRY TUESDAY.
WEDNESDAY AND THURSDAY WILL BE IN DRY WEST TO NORTHWESTERLY ZONAL
FLOW WITH NEAR NORMAL TEMPERATURES. THE PRECIPITATION FORECAST
LOOKS GRIM IN THIS FLOW AS THE CLOSEST AREA OF MOISTURE OVER THE
NORTHERN STATES LOOKS LIKE IT WILL KEEP TO THE NORTH.
&&
.AVIATION...WARM SOUTH TO SOUTHWEST SURFACE WINDS EARLY THIS
MORNING WILL GRADUALLY VEER AROUND TO WESTERLY AND INCREASE IN
SPEED AND GUSTINESS AS BORA CONDITIONS DEVELOP BEHIND THE TROUGH
PASSAGE BY LATER THIS MORNING. GUSTY WESTERLIES CAN BE EXPECTED
THROUGHOUT THE LATER MORNING AND AFTERNOON BEFORE TURNING TO NORTH
AND THEN EAST AND DECREASING OVERNIGHT. WITH A SMALL THREAT OF
SHOWER ACTIVITY LOWER CEILINGS AND BRIEF LOWERED VISIBILITIES ARE
A SMALL POSSIBILITY...MAINLY THIS MORNING. SOME STRATUS MAY BE
AROUND LATER TONIGHT BUT IFR CONDITIONS ARE NOT EXPECTED AT THIS
TIME.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...WINTER WEATHER ADVISORY UNTIL
5 AM MST SATURDAY FOR COZ031.
&&
$$
SHORT TERM...ET
LONG TERM....KRIEDERMAN
AVIATION...ET
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1018 AM EST FRI JAN 11 2013
.SYNOPSIS...
A WEAK WARM FRONT WILL SHIFT NORTH OF THE FORECAST AREA THIS
AFTERNOON. TEMPERATURES THIS WEEKEND INTO EARLY NEXT WEEK WILL
BE WELL ABOVE NORMAL AS AN UPPER RIDGE REMAINS OVER THE AREA. THE
CHANCE FOR RAIN INCREASES DURING THE MIDDLE OF NEXT WEEK AS A SLOW
MOVING COLD FRONT PUSHES INTO THE AREA.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATE THIS MORNING...WARM FRONT STILL SOUTH OF THE REGION AND
SLOW TO MOVE NORTH. THE LONGER IT REMAINS TO THE SOUTH...THE
LONGER THE FOG WILL PERSIST. EXTENDED THE DENSE FOG ADVISORY
THROUGH 11 AM. ISENTROPIC LIFT AND A MID- LEVEL SHORTWAVE TROUGH
SUPPORTS RAIN. RUC MODEL IS SHOWING WEAK SHORT WAVE EMBEDDED IN
UPPER RIDGE THAT IS MOVING THROUGH THE AREA THIS MORNING.
INCREASED POPS TO 40-50 PERCENT NORTH PART WHERE SHORT WAVE CAUSED
SHOWERS TO FORM AND WILL KEEP MAINLY 20 PERCENT ELSEWHERE.
THIS AFTERNOON...WARM FRONT MOVES THROUGH...POPS DROP TO LESS
THAN 20 PERCENT. AS THE WARM FRONT LIFTS NORTH OF THE AREA EXPECT
BREAKS IN THE CLOUDINESS WILL OCCUR LATER TODAY. BECAUSE OF THE
SLOW MOVEMENT OF THE WARM FRONT...LOWERED HIGH TEMPERATURES TO
MIDDLE TO UPPER 60S NORTH TO LOWER TO MIDDLE 70S IN THE SOUTH.
TONIGHT...THE UPPER RIDGE WILL BUILD BACK OVER THE FORECAST AREA
AND UP THE EAST COAST TONIGHT. WITH PLENTY OF LOW LEVEL MOISTURE
EXPECT AREAS OF FOG TO DEVELOP MUCH LIKE THIS MORNING.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
THE UPPER RIDGE WILL BUILD BACK OVER THE FORECAST AREA AND UP THE
EAST COAST SATURDAY AS THE WEST COAST TROUGH DEEPENS ONCE AGAIN.
SURFACE HIGH PRESSURE WILL BE CENTERED OFF THE CAROLINA COAST AND
PROVIDE A WARM SOUTHWESTERLY BOUNDARY LAYER FLOW. THE MAIN PWAT
AXIS AND MOISTURE FLUX TRANSPORT WILL REMAIN OVER THE MISSISSIPPI
AND TENNESSEE VALLEYS THROUGH THE PERIOD AND EXPECT A GENERALLY
DRY FORECAST OVER THE MIDLANDS AND CSRA.
TEMPERATURES WILL BE THE MAIN INTEREST THIS WEEKEND AS LATE SPRING
LIKE TEMPERATURES ARE EXPECTED WITH MAX TEMPS SOME 15-20 DEGREES
ABOVE NORMAL. RECORD HIGH TEMPERATURES WILL BE IN JEOPARDY OF
FALLING BOTH SATURDAY AND SUNDAY ACROSS THE REGION WHILE OVERNIGHT
LOW TEMPERATURES ARE FORECAST TO BE IN THE MID TO UPPER 50S WHICH
IS AROUND WHAT OUR NORMAL HIGH TEMPERATURES ARE THIS TIME OF YEAR.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE EXTENDED FORECAST FEATURES A HIGHLY AMPLIFIED UPPER PATTERN
EARLY NEXT WEEK WITH A LARGE POSITIVELY TILTED TROUGH ACROSS MUCH
OF THE WESTERN TWO THIRDS OF THE COUNTRY WITH THE UPPER RIDGE AXIS
SHIFTED WELL OFF THE EAST COAST. MONDAY SHOULD BE DRY FOR MOST OF
THE AREA BUT SOME SHOWERS WILL BE POSSIBLE IN THE NORTHERN AND
WESTERN MIDLANDS MONDAY AFTERNOON AS A SLOW MOVING COLD FRONT
WHICH WILL BE FOCUSING FLOODING RAINS OVER THE MISSISSIPPI AND
TENNESSEE VALLEYS DRIFTS SLOWLY EASTWARD TOWARDS THE FORECAST
AREA. TEMPERATURES ON MONDAY WILL AGAIN BE WELL ABOVE NORMAL IN
THE 70S AND LOWS MONDAY NIGHT WILL BE MILD IN THE MID TO UPPER
50S.
AS NORTHERN STREAM ENERGY DROPS INTO THE LONGWAVE TROUGH BY
TUESDAY...HEIGHTS WILL FALL OVER THE FORECAST AREA AND THE FRONT
WILL GRADUALLY MOVE INTO THE AREA. THE FRONT WILL BE SLOW TO PUSH
ACROSS THE REGION DUE TO ITS NEARLY PARALLEL ORIENTATION TO THE
UPPER FLOW AND THIS WILL BRING INCREASED CHANCES OF RAIN TUESDAY
AND WEDNESDAY WITH THE FRONTAL BOUNDARY NEARBY. HAVE INCREASED
POPS A BIT INTO THE HIGHER CHANCE RANGE TUESDAY THROUGH
WEDNESDAY...AND THEY MAY NEED TO BE INCREASED FURTHER ON LATER
SHIFTS...AS MOISTURE TRANSPORT AND PWAT VALUES INCREASE WITHIN THE
FRONTAL ZONE. TEMPERATURES WILL BEGIN TO COOL A BIT BY MID WEEK
BUT WILL LIKELY EXHIBIT A STRONG GRADIENT ACROSS THE FORECAST AREA
ON TUESDAY FROM SOUTHEAST TO NORTHWEST. CONFIDENCE LOWERS LATE IN
THE LONG TERM AS MODEL CONSISTENCY DIMINISHES.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
CONVERGENCE ASSOCIATED WITH THE WARM FRONT HAS RESULTED IN STRATUS
AND FOG THIS MORNING. AS THE FRONT LIFTS NORTH OF THE AREA
IMPROVEMENT SHOULD OCCUR. THE GFS AND NAM MOS WERE IN GOOD
AGREEMENT MAINTAINING IFR CONDITIONS THROUGH THIS MORNING...WITH
MVFR AND VFR CEILINGS DEVELOPING THIS AFTERNOON. DIURNAL COOLING
WITH CONTINUED HIGH LOW-LEVEL MOISTURE SHOULD RESULT IN A RETURN
OF STRATUS AND FOG TONIGHT. USED THE GFS LAMP FOR THE TIMING OF
IFR CONDITIONS.
EXTENDED AVIATION OUTLOOK...THERE WILL LIKELY BE SUFFICIENT
LOW-LEVEL MOISTURE FOR WIDESPREAD MVFR OR IFR CEILINGS AND
VISIBILITIES DURING THE EARLY MORNING HOURS SATURDAY THROUGH
MONDAY. RESTRICTIONS ASSOCIATED WITH A FRONTAL SYSTEM MAY OCCUR
TUESDAY.
&&
.CLIMATE...
RECORD HIGH TEMPERATURE INFORMATION FOR JANUARY 12/13/14:
SATURDAY JAN 12TH RECORD HIGHS...
CAE: 77 (1916)
AGS: 78 (1916)
SUNDAY JAN 13TH RECORD HIGHS...
CAE: 77 (2005)
AGS: 79 (2005)
MONDAY JAN 14TH RECORD HIGHS...
CAE: 80 (1932)
AGS: 84 (1932)
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...DENSE FOG ADVISORY UNTIL 11 AM EST THIS MORNING FOR SCZ015-016-
018-020>022-025>031-035>038-041.
GA...DENSE FOG ADVISORY UNTIL 11 AM EST THIS MORNING FOR GAZ040-
063>065-077.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
958 AM EST FRI JAN 11 2013
.SYNOPSIS...
A WEAK WARM FRONT WILL SHIFT NORTH OF THE FORECAST AREA THIS
AFTERNOON. TEMPERATURES THIS WEEKEND INTO EARLY NEXT WEEK WILL
BE WELL ABOVE NORMAL AS AN UPPER RIDGE REMAINS OVER THE AREA. THE
CHANCE FOR RAIN INCREASES DURING THE MIDDLE OF NEXT WEEK AS A SLOW
MOVING COLD FRONT PUSHES INTO THE AREA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WARM FRONT STILL SOUTH OF THE REGION AND SLOW TO MOVE NORTH.
THE LONGER IT REMAINS TO THE SOUTH...THE LONGER THE FOG WILL
PERSIST. EXTENDED THE DENSE FOG ADVISORY THROUGH 11 AM. OTHERWISE...
FOR LATE THIS MORNING AND THIS AFTERNOON...ISENTROPIC LIFT AND A
MID-LEVEL SHORTWAVE TROUGH SUPPORTS RAIN. RUC MODEL IS SHOWING
WEAK SHORT WAVE EMBEDDED IN UPPER RIDGE THAT IS MOVING THROUGH
THE AREA THIS MORNING. INCREASED POPS TO 40-50 PERCENT NORTH PART
WHERE SHORT WAVE CAUSED SHOWERS TO FORM AND WILL KEEP MAINLY 20
PERCENT ELSEWHERE. AFTER WARM FRONT MOVES THROUGH...POPS THIS
AFTERNOON DROP TO LESS THAN 20 PERCENT. AS THE WARM FRONT LIFTS
NORTH OF THE AREA EXPECT BREAKS IN THE CLOUDINESS WILL OCCUR LATER
TODAY. BECAUSE OF THE SLOW MOVEMENT OF THE WARM FRONT...LOWERED
HIGH TEMPERATURES TO MIDDLE TO UPPER 60S NORTH TO LOWER TO MIDDLE
70S IN THE SOUTH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
THE UPPER RIDGE WILL BUILD BACK OVER THE FORECAST AREA AND UP THE
EAST COAST TONIGHT THROUGH SATURDAY AS THE WEST COAST TROUGH
DEEPENS ONCE AGAIN. SURFACE HIGH PRESSURE WILL BE CENTERED OFF THE
CAROLINA COAST AND PROVIDE A WARM SOUTHWESTERLY BOUNDARY LAYER
FLOW. THE MAIN PWAT AXIS AND MOISTURE FLUX TRANSPORT WILL REMAIN
OVER THE MISSISSIPPI AND TENNESSEE VALLEYS THROUGH THE PERIOD AND
EXPECT A GENERALLY DRY FORECAST OVER THE MIDLANDS AND CSRA.
TEMPERATURES WILL BE THE MAIN INTEREST THIS WEEKEND AS LATE SPRING
LIKE TEMPERATURES ARE EXPECTED WITH MAX TEMPS SOME 15-20 DEGREES
ABOVE NORMAL. RECORD HIGH TEMPERATURES WILL BE IN JEOPARDY OF
FALLING BOTH SATURDAY AND SUNDAY ACROSS THE REGION WHILE OVERNIGHT
LOW TEMPERATURES ARE FORECAST TO BE IN THE MID TO UPPER 50S WHICH
IS AROUND WHAT OUR NORMAL HIGH TEMPERATURES ARE THIS TIME OF YEAR.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE EXTENDED FORECAST FEATURES A HIGHLY AMPLIFIED UPPER PATTERN
EARLY NEXT WEEK WITH A LARGE POSITIVELY TILTED TROUGH ACROSS MUCH
OF THE WESTERN TWO THIRDS OF THE COUNTRY WITH THE UPPER RIDGE AXIS
SHIFTED WELL OFF THE EAST COAST. MONDAY SHOULD BE DRY FOR MOST OF
THE AREA BUT SOME SHOWERS WILL BE POSSIBLE IN THE NORTHERN AND
WESTERN MIDLANDS MONDAY AFTERNOON AS A SLOW MOVING COLD FRONT
WHICH WILL BE FOCUSING FLOODING RAINS OVER THE MISSISSIPPI AND
TENNESSEE VALLEYS DRIFTS SLOWLY EASTWARD TOWARDS THE FORECAST
AREA. TEMPERATURES ON MONDAY WILL AGAIN BE WELL ABOVE NORMAL IN
THE 70S AND LOWS MONDAY NIGHT WILL BE MILD IN THE MID TO UPPER
50S.
AS NORTHERN STREAM ENERGY DROPS INTO THE LONGWAVE TROUGH BY
TUESDAY...HEIGHTS WILL FALL OVER THE FORECAST AREA AND THE FRONT
WILL GRADUALLY MOVE INTO THE AREA. THE FRONT WILL BE SLOW TO PUSH
ACROSS THE REGION DUE TO ITS NEARLY PARALLEL ORIENTATION TO THE
UPPER FLOW AND THIS WILL BRING INCREASED CHANCES OF RAIN TUESDAY
AND WEDNESDAY WITH THE FRONTAL BOUNDARY NEARBY. HAVE INCREASED
POPS A BIT INTO THE HIGHER CHANCE RANGE TUESDAY THROUGH
WEDNESDAY...AND THEY MAY NEED TO BE INCREASED FURTHER ON LATER
SHIFTS...AS MOISTURE TRANSPORT AND PWAT VALUES INCREASE WITHIN THE
FRONTAL ZONE. TEMPERATURES WILL BEGIN TO COOL A BIT BY MID WEEK
BUT WILL LIKELY EXHIBIT A STRONG GRADIENT ACROSS THE FORECAST AREA
ON TUESDAY FROM SOUTHEAST TO NORTHWEST. CONFIDENCE LOWERS LATE IN
THE LONG TERM AS MODEL CONSISTENCY DIMINISHES.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
CONVERGENCE ASSOCIATED WITH THE WARM FRONT HAS RESULTED IN STRATUS
AND FOG THIS MORNING. AS THE FRONT LIFTS NORTH OF THE AREA
IMPROVEMENT SHOULD OCCUR. THE GFS AND NAM MOS WERE IN GOOD
AGREEMENT MAINTAINING IFR CONDITIONS THROUGH THIS MORNING...WITH
MVFR AND VFR CEILINGS DEVELOPING THIS AFTERNOON. DIURNAL COOLING
WITH CONTINUED HIGH LOW-LEVEL MOISTURE SHOULD RESULT IN A RETURN
OF STRATUS AND FOG TONIGHT. USED THE GFS LAMP FOR THE TIMING OF
IFR CONDITIONS.
EXTENDED AVIATION OUTLOOK...THERE WILL LIKELY BE SUFFICIENT
LOW-LEVEL MOISTURE FOR WIDESPREAD MVFR OR IFR CEILINGS AND
VISIBILITIES DURING THE EARLY MORNING HOURS SATURDAY THROUGH
MONDAY. RESTRICTIONS ASSOCIATED WITH A FRONTAL SYSTEM MAY OCCUR
TUESDAY.
&&
.CLIMATE...
RECORD HIGH TEMPERATURE INFORMATION FOR JANUARY 12/13/14:
SATURDAY JAN 12TH RECORD HIGHS...
CAE: 77 (1916)
AGS: 78 (1916)
SUNDAY JAN 13TH RECORD HIGHS...
CAE: 77 (2005)
AGS: 79 (2005)
MONDAY JAN 14TH RECORD HIGHS...
CAE: 80 (1932)
AGS: 84 (1932)
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...DENSE FOG ADVISORY UNTIL 11 AM EST THIS MORNING FOR SCZ015-016-
018-020>022-025>031-035>038-041.
GA...DENSE FOG ADVISORY UNTIL 11 AM EST THIS MORNING FOR GAZ040-
063>065-077.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
258 AM EST FRI JAN 11 2013
.SYNOPSIS...
A WEAK WARM FRONT WILL SHIFT NORTH OF THE FORECAST AREA TODAY.
TEMPERATURES THIS WEEKEND INTO EARLY NEXT WEEK WILL BE WELL ABOVE
NORMAL AS AN UPPER RIDGE REMAINS OVER THE AREA. THE CHANCE FOR
RAIN INCREASES DURING THE MIDDLE OF NEXT WEEK AS A SLOW MOVING
COLD FRONT PUSHES INTO THE AREA.
&&
.NEAR TERM /THROUGH TODAY/...
CONVERGENCE ASSOCIATED WITH THE WARM FRONT HAS RESULTED IN
WIDESPREAD LOW CLOUDINESS AND FOG. THE FOG MAY BECOME DENSE. A DENSE
FOG ADVISORY MAY BE NEEDED. ISENTROPIC LIFT AND A MID-LEVEL
SHORTWAVE TROUGH SUPPORTS RAIN. THE LATEST RAP SHOWS THE MOST LIFT
AND MOISTURE ASSOCIATED WITH THE TROUGH IN THE NORTH AND WEST
SECTIONS 12Z TO 15Z THIS MORNING. FORECASTED HIGHER POPS DURING THIS
TIME. OTHERWISE...EXPECT MOISTURE WILL BE SHALLOW AND ISENTROPIC
LIFT WEAK SUPPORTING VERY LOW POPS. AS THE WARM FRONT LIFTS NORTH OF
THE AREA EXPECT BREAKS IN THE CLOUDINESS WILL OCCUR LATER TODAY. IT
WILL BE ANOTHER WARM DAY. USED THE GFS AND NAM MOS AND FORECASTED
HIGHS IN THE UPPER 60S NORTH TO MIDDLE AND UPPER 70S SOUTH.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
THE UPPER RIDGE WILL BUILD BACK OVER THE FORECAST AREA AND UP THE
EAST COAST TONIGHT THROUGH SATURDAY AS THE WEST COAST TROUGH
DEEPENS ONCE AGAIN. SURFACE HIGH PRESSURE WILL BE CENTERED OFF THE
CAROLINA COAST AND PROVIDE A WARM SOUTHWESTERLY BOUNDARY LAYER
FLOW. THE MAIN PWAT AXIS AND MOISTURE FLUX TRANSPORT WILL REMAIN
OVER THE MISSISSIPPI AND TENNESSEE VALLEYS THROUGH THE PERIOD AND
EXPECT A GENERALLY DRY FORECAST OVER THE MIDLANDS AND CSRA.
TEMPERATURES WILL BE THE MAIN INTEREST THIS WEEKEND AS LATE SPRING
LIKE TEMPERATURES ARE EXPECTED WITH MAX TEMPS SOME 15-20 DEGREES
ABOVE NORMAL. RECORD HIGH TEMPERATURES WILL BE IN JEOPARDY OF
FALLING BOTH SATURDAY AND SUNDAY ACROSS THE REGION WHILE OVERNIGHT
LOW TEMPERATURES ARE FORECAST TO BE IN THE MID TO UPPER 50S WHICH
IS AROUND WHAT OUR NORMAL HIGH TEMPERATURES ARE THIS TIME OF YEAR.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE EXTENDED FORECAST FEATURES A HIGHLY AMPLIFIED UPPER PATTERN
EARLY NEXT WEEK WITH A LARGE POSITIVELY TILTED TROUGH ACROSS MUCH
OF THE WESTERN TWO THIRDS OF THE COUNTRY WITH THE UPPER RIDGE AXIS
SHIFTED WELL OFF THE EAST COAST. MONDAY SHOULD BE DRY FOR MOST OF
THE AREA BUT SOME SHOWERS WILL BE POSSIBLE IN THE NORTHERN AND
WESTERN MIDLANDS MONDAY AFTERNOON AS A SLOW MOVING COLD FRONT
WHICH WILL BE FOCUSING FLOODING RAINS OVER THE MISSISSIPPI AND
TENNESSEE VALLEYS DRIFTS SLOWLY EASTWARD TOWARDS THE FORECAST
AREA. TEMPERATURES ON MONDAY WILL AGAIN BE WELL ABOVE NORMAL IN
THE 70S AND LOWS MONDAY NIGHT WILL BE MILD IN THE MID TO UPPER
50S.
AS NORTHERN STREAM ENERGY DROPS INTO THE LONGWAVE TROUGH BY
TUESDAY...HEIGHTS WILL FALL OVER THE FORECAST AREA AND THE FRONT
WILL GRADUALLY MOVE INTO THE AREA. THE FRONT WILL BE SLOW TO PUSH
ACROSS THE REGION DUE TO ITS NEARLY PARALLEL ORIENTATION TO THE
UPPER FLOW AND THIS WILL BRING INCREASED CHANCES OF RAIN TUESDAY
AND WEDNESDAY WITH THE FRONTAL BOUNDARY NEARBY. HAVE INCREASED
POPS A BIT INTO THE HIGHER CHANCE RANGE TUESDAY THROUGH
WEDNESDAY...AND THEY MAY NEED TO BE INCREASED FURTHER ON LATER
SHIFTS...AS MOISTURE TRANSPORT AND PWAT VALUES INCREASE WITHIN THE
FRONTAL ZONE. TEMPERATURES WILL BEGIN TO COOL A BIT BY MID WEEK
BUT WILL LIKELY EXHIBIT A STRONG GRADIENT ACROSS THE FORECAST AREA
ON TUESDAY FROM SOUTHEAST TO NORTHWEST. CONFIDENCE LOWERS LATE IN
THE LONG TERM AS MODEL CONSISTENCY DIMINISHES.
&&
.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
CONVERGENCE ASSOCIATED WITH THE WARM FRONT HAS RESULTED IN STRATUS
AND FOG THIS MORNING. AS THE FRONT LIFTS NORTH OF THE AREA
IMPROVEMENT SHOULD OCCUR. THE GFS AND NAM MOS WERE IN GOOD
AGREEMENT MAINTAINING IFR CONDITIONS THROUGH THIS MORNING...WITH
MVFR AND VFR CEILINGS DEVELOPING THIS AFTERNOON.
EXTENDED AVIATION OUTLOOK...THERE WILL LIKELY BE SUFFICIENT
LOW-LEVEL MOISTURE FOR WIDESPREAD MVFR OR IFR CEILINGS AND
VISIBILITIES DURING THE EARLY MORNING HOURS SATURDAY THROUGH
MONDAY. RESTRICTIONS ASSOCIATED WITH A FRONTAL SYSTEM MAY OCCUR
TUESDAY.
&&
.CLIMATE...
RECORD HIGH TEMPERATURE INFORMATION FOR JANUARY 12/13/14:
SATURDAY JAN 12TH RECORD HIGHS...
CAE: 77 (1916)
AGS: 78 (1916)
SUNDAY JAN 13TH RECORD HIGHS...
CAE: 77 (2005)
AGS: 79 (2005)
MONDAY JAN 14TH RECORD HIGHS...
CAE: 80 (1932)
AGS: 84 (1932)
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...RJL/HC
NEAR TERM...RJL
SHORT TERM...HC
LONG TERM...HC
AVIATION...RJL
CLIMATE...HC
AREA FORECAST DISCUSSION
NWS LINCOLN IL
853 PM CST SAT JAN 12 2013
.DISCUSSION...
ISSUED 853 PM CST SAT JAN 12 2013
TRICKY PRECIPITATION TYPE FORECAST TONIGHT ACROSS MUCH OF
CENTRAL/SOUTHEAST ILLINOIS FOR THE REST OF THE NIGHT. SIGNS ARE
STARTING TO POINT TO MORE OF A FREEZING RAIN PROBLEM IN MUCH OF
THE FORECAST AREA. 00Z ILX SOUNDING...AS WELL AS 00Z NAM AND
LATEST RAP SOUNDINGS...SUGGEST A MORE SIGNIFICANT ELEVATED WARM
LAYER THAN WAS PREVIOUSLY ANTICIPATED. IN ADDITION...SURFACE
TEMPERATURES ARE FALLING TO 32 DEGREES OR COLDER A LITTLE QUICKER
AS WELL. THE SURFACE FREEZING LINE CURRENTLY RESIDES IN THE
VICINITY OF THE I-55 CORRIDOR.
THIS DIFFERENCE IN THERMAL PROFILE WILL REQUIRE A FEW TWEAKS TO
THE FORECAST. THE RISK FOR APPRECIABLE SLEET APPEARS TO HAVE FADED
AS IT LOOKS LIKE THE ELEVATED WARM SHOULD COOL QUICKLY WHEN IT
DOES SO...SIGNALING A RAPID CHANGE OVER FROM RAIN/FREEZING RAIN TO
SNOW. SO...PLAN TO REMOVE MOST MENTIONS OF SLEET. THE MORE
PRONOUNCED ELEVATED WARM LAYER AND MORE RAPID SURFACE COOLING HAS
RESULTED IN FREEZING RAIN FALLING FURTHER WEST THAN ANTICIPATED
AND WILL MAKE ADJUSTMENTS TO PUSH FREEZING RAIN WEST TO THE
ILLINOIS RIVER VALLEY. FINALLY...WILL HAVE TO PUSH THE CHANGE OVER
FROM RAIN TO FREEZING RAIN EAST A BIT MORE QUICKLY.
THERE IS SOME CONCERN WITH FREEZING RAIN BECOMING MORE OF A
PREDOMINANT WEATHER TYPE THAT MORE SIGNIFICANT ICING MAY BECOME A
THREAT. HOWEVER...FEEL THAT THE RAPID END OF THE HEAVIER
PRECIPITATION...BY SHORTLY AFTER MIDNIGHT...WILL PRECLUDE THE
NEED OF AN UPGRADE TO A WARNING. THIS THREAT WILL BE WATCHED
CLOSELY.
BAK
&&
.AVIATION...
ISSUED 557 PM CST SAT JAN 12 2013
A QUICK MOVING WEATHER DISTURBANCE WILL TRACK NORTHEAST ALONG THE
FRONTAL BOUNDARY THAT CLEARED THE CENTRAL ILLINOIS TERMINALS
EARLIER TODAY. THIS DISTURBANCE WILL SPREAD/CONTINUE TO SPREAD
PRECIPITATION INTO THE AREA THROUGH EARLY SUNDAY. THE HEAVIEST
PRECIPITATION SHOULD FALL THIS EVENING...WITH MOSTLY RAIN LIKELY
AT KCMI/KDEC...AND MORE OF A MIXED PRECIPITATION THREAT FOR
KSPI/KBMI/KPIA. EXPECT CONDITIONS TO RAPIDLY DEGRADE TO IFR OVER
THE NEXT FEW HOURS ONCE THE PRECIPITATION GETS MORE WIDESPREAD.
EXPECT CONDITIONS TO IMPROVE TO MVFR SUNDAY AS THE PRECIPITATION
TAPERS OFF AND DRIER AIR FILTERS INTO THE AREA.
BAK
&&
.PREV DISCUSSION...
QUICK MOVING WEATHER SYSTEM TO BRING A PERIOD OF FREEZING
RAIN...SLEET AND SNOW THIS EVENING/OVERNIGHT IN ALL AREAS BUT FAR
EAST CENTRAL AND SOUTHEAST IL WHERE HEAVY RAINFALL IS A THREAT.
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
UPPER WAVE OF INTEREST BEGINNING TO EJECT NORTHEAST OUT OF THE BASE
OF THE TROF OVER THE SOUTHWEST PORTION OF THE COUNTRY WITH MODELS
ACCELERATING THE FEATURE NORTHEAST THRU THE LOWER GREAT LAKES BY
SUNDAY MORNING. THAT IS ABOUT THE ONLY SAVING GRACE WITH THE UPPER
WAVE IS THE FACT THAT IT WILL BE A QUICK MOVER...OTHERWISE WE WOULD
BE SEEING A LARGE AREA OF SIGNIFICANT ICING OVER PARTS OF CENTRAL IL
LATER TONIGHT. EVEN SO...THE NAM-WRF SOUNDINGS ARE SHOWING A MUCH
LARGER AND LONGER LASTING WARM LAYER (6-8 DEGREES DEPICTED ON THE
RAPID REFRESH MODEL AT SPI-BMI LATER THIS EVE) BETWEEN 800 AND 700 MB
THAN BEFORE...WHICH SUGGESTS THE POTENTIAL FOR LONGER DURATION OF
FREEZING RAIN AND SLEET...ESPECIALLY RIGHT UP THE I-55 CORRIDOR LATER
THIS EVENING WHERE A TENTH TO TWO TENTHS OF AN INCH MAY ACCUMULATE.
ONLY MITIGATING FACTORS WILL BE THE SPEED OF THE SYSTEM AND THAT WE
HAVE HAD A COUPLE OF DAYS WITH SURFACE TEMPS IN THE 50S...SO
INITIALLY...ROADWAYS WILL BE WET INTO THE EVENING BEFORE THE TRANSITION
OCCURS.
FURTHER WEST...ROUGHLY WEST OF THE ILLINOIS RIVER...SEEING SOME POTENTIAL
FOR SOME BRIEF MESOSCALE BANDING (NEGATIVE EPV OVER A PRONOUNCED BAND
OF FRONTOGENETICAL FORCING) OF THE PRECIP BEFORE WE LOSE OUR ICE CRYSTALS
AFTER 06Z WHICH WOULD ENHANCE THE SNOWFALL TOTALS. RIGHT NOW WE ARE
LOOKING AT 2-3 INCHES WEST OF THE ILLINOIS RIVER WITH LESSER AMOUNTS AS
YOU HEAD EAST AS SOUNDINGS INDICATE THE WARM LAYER ABOVE 800 MB HOLDS
IN PLACE UNTIL DAWN SUNDAY. BUT BY THEN...MOST FORECAST SOUNDINGS EVEN
INTO EASTERN ILLINOIS INDICATE THE LOSS OFF ICE CRYSTALS WHICH WOULD
SUGGEST THE THREAT FOR MORE FREEZING DRIZZLE OR FLURRIES...DEPENDING
ON HOW DEEP THE COLD LAYER IS IN THE LOWER LEVELS OF THE ATMOSPHERE.
A WINTER WEATHER ADVISORY WILL BE IN EFFECT STARTING EARLY THIS EVENING
WEST AND THEN ALONG THE I-57 CORRIDOR BY MIDNIGHT TO ADDRESS THE THREAT
FOR A COMBINATION OF SNOW...SLEET AND FREEZING RAIN.
ACROSS SOUTHEAST ILLINOIS...THE TRANSPORT OF MOISTURE NORTHWARD INTO
THE AREA AHEAD OF THE SYSTEM IS VERY IMPRESSIVE FOR THE SECOND WEEK
OF JANUARY WITH PRECIP WATER VALUES OF 1.50 INCHES. RAIN WITH ISOLD
THUNDERSTORMS WILL BRING AN ADDITIONAL 1-2 INCHES OF RAIN TO THE
WABASH...LITTLE WABASH AND EMBARRAS BASINS WHICH THREATENS TO BRING
THOSE BASINS TO FLOOD. AS A RESULT...WILL HAVE A FLOOD WATCH FOR OUR
FAR SOUTHEAST COUNTIES UNTIL NOON SUNDAY TO ADDRESS THE INCREASING
THREAT FOR MORE WIDESPREAD RIVER FLOODING.
AS THE WEATHER SYSTEM DEPARTS SUNDAY MORNING...LINGERING FLURRIES OR
FREEZING DRIZZLE WILL COME TO AN END. HOWEVER...MODELS INDICATE A
SECONDARY WAVE ASSOCIATED WITH A 250 MB SPEED MAX WILL PUT FAR EAST
CENTRAL AND ESPECIALLY SOUTHEAST IL IN THE RIGHT REAR QUAD OF THE
JET WHICH WILL ENHANCE THE UPWARD VERTICAL MOTION AND BRING ANOTHER
ROUND OF PRECIP SUNDAY AFTERNOON INTO EARLY EVENING. HAVE UPPED POPS
IN THAT AREA WITH FORECAST SOUNDINGS INDICATING A MESSY MIXTURE OF
SLEET...FREEZING RAIN AND SNOW FOR A BRIEF PERIOD BEFORE THE JET
SUPPORT SHIFTS AWAY FROM THE AREA BY 00Z MONDAY. AFTER THAT...QUIET
BUT COLDER WEATHER WILL PREVAIL THRU THE REMAINDER OF THE SHORT TERM
PERIOD WITH DAYTIME HIGHS IN THE 20S NORTH...TO THE LOW TO MID 30S
FAR SOUTHEAST WITH EARLY MORNING LOWS DIPPING INTO THE TEENS MOST
AREAS.
LONG TERM...WEDNESDAY THROUGH SATURDAY
COLD VORTEX OVER HUDSON BAY FORECAST BY MEDIUM RANGE MODELS TO
EVENTUALLY SHIFT SOUTH BRINGING A SURGE OF ARCTIC AIR INTO THE
GREAT LAKES REGION...BUT TIMING OF THAT OCCURRENCE IS HANDLED A
BIT DIFFERENTLY FROM WHAT WE SAW YESTERDAY WITH A SLOWER TRANSITION
TO THE COLDER PATTERN BY LATE NEXT WEEKEND.
WITH THE 500 MB UPPER LOW IN HUDSON BAY BEING THE DOMINANT WEATHER
FEATURE THIS PERIOD...MOST OF THE SIGNIFICANT WEATHER SYSTEMS WILL
TAKE A MORE SOUTHERLY TRACK WELL SOUTH OF OUR AREA DURING THIS
PERIOD WITH OUR WEATHER COMING FROM THE NORTHWEST. ANY SOUTHEAST
MOVING SHORTWAVE IN THIS FLOW PATTERN WILL BE WEAK AND MOISTURE
STARVED...AS A RESULT...WILL CONTINUE TO KEEP THE EXTENDED DRY
WITH A GRADUAL WARMING TREND AS WE HEAD INTO NEXT WEEK AS THE
CANADIAN UPPER LOW TEMPORARILY WOBBLES BACK TO THE NORTH BEFORE
HEADING SOUTH TOWARDS THE LOWER 48 JUST AFTER THIS FORECAST
PERIOD.
SHORT TERM...07
LONG TERM....SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH THROUGH SUNDAY MORNING FOR ILZ063-067-068-071>073.
WINTER WEATHER ADVISORY UNTIL NOON CST SUNDAY FOR ILZ027>031-036-
037-040-041-047>050.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST SUNDAY
FOR ILZ044>046-054>056-061.
WINTER WEATHER ADVISORY UNTIL NOON CST SUNDAY FOR ILZ038-042-043-
051>053.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
933 PM CST SAT JAN 12 2013
.UPDATE...
NOW THAT WE ARE GETTING NUMEROUS REPORTS OF SNOW AND SLEET
BEGINNING ACROSS THE FORECAST AREA...A BETTER SPECIFICATION CAN BE
MADE AS TO WHERE THE SNOW/SLEET LINE CAN BE MADE. EXPECT THAT
LOCATIONS AROUND MACOMB...AND ALSO AROUND PRINCETON ARE GETTING A
WINTERY MIXTURE OF SLEET AND POSSIBLY EVEN FREEZING RAIN AS WELL.
THIS MIXTURE MAY ALSO AFFECT KEWANEE AND PORTIONS OF HENRY COUNTY...AND
EASTERN WARREN COUNTIES AS WELL IN THE NEXT FEW HOURS. WSR-88D
DUAL POL DATA IS SHOWING AREAS WHERE SLEET IS EXPECTED QUITE
NICELY THIS EVENING. HAVE MADE SOME ADJUSTMENTS TO THE FORECAST TO
REFLECT THE CURRENT TRENDS...BUT HAVE KEPT SNOWFALL AMOUNTS ABOUT
THE SAME AS BEFORE. IF THE SLEET CONTINUES FOR TOO LONG IN THE
SOUTHEAST...THE SNOWFALL FORECAST MAY NEED TO BE REDUCED IN THOSE
AREAS.
&&
.PREV DISCUSSION... /ISSUED 303 PM CST SAT JAN 12 2013/
SYNOPSIS...
COLD FRONT PUSHING INTO THE OHIO VALLEY THIS AFTERNOON...WITH COLD
AIR OOZING INTO THE UPPER MISSISSIPPI VALLEY BEHIND IT. LONG WAVE
TROUGH SPANNING THE ROCKIES...WITH ENERGY LIFTING OUT OVER THE
CENTRAL US IN FAST SOUTHWEST FLOW. LEAD SHORTWAVE GENERATING SOME
SNOW/SLEET OVER NORTHERN MO AND INTO SE IA AT THIS TIME. MAIN
PRECIP AREA ACROSS SOUTHERN MO AND SOUTHERN ILLINOIS IS ALSO
EXPANDING NORTHWARD AND IS NOW PUSHING INTO CENTRAL ILLINOIS AHEAD
OF THE MAIN SHORT WAVE...WHICH CAN BE SEEN ON SATELLITE LIFTING OUT
OF ARKANSAS.
SHORT TERM...TONIGHT AND SUNDAY...
MAIN FORECAST QUESTIONS THIS AFTERNOON CENTER AROUND DEVELOPING
PRECIPITATION EVENT FOR TONIGHT. THE INITIAL WAVE OF LIGHT SNOW/SLEET
NOW MOVING ACROSS EASTERN IA WILL HELP COOL AND SATURATE THE COLUMN
AHEAD OF TONIGHTS WAVE BUT WILL HAVE LITTLE OTHER IMPACT. FOR TONIGHT...OF
THE SHORT RANGE MODELS...THE RAP IS THE MOST AGGRESSIVE WITH
SNOWFALL AMOUNTS...SUGGESTING 4 TO 6 INCHES ALONG AND EAST OF THE
MISSISSIPPI RIVER. MEANWHILE...THE NAM...GFS...AND ECMWF ARE MORE
CONSERVATIVE WITH 2-3 INCHES AT MOST. THUS WILL FAVOR A BLEND OF
THE NAM AND ECMWF FOR THIS FORECAST...ESPECIALLY FOR MOISTURE PARAMETERS.
THERE IS CONSISTENCY IN THE FORECAST SOUNDINGS...SHOWING A LARGE
WEDGE OF WARM AIR ALOFT...ESPECIALLY EAST OF THE MISSISSIPPI
RIVER...THAT WILL HAVE TO COOL BEFORE PRECIP CHANGES TO SNOW.
CURRENT THINKING IS THAT NEAR THE RIVER THE PERIOD OF SLEET SHOULD
BE BRIEF...BUT WILL LAST LONGER AS YOU GO EAST. BUREAU/PUTNAM
COUNTIES COULD SEE A COUPLE OF HOURS OF SLEET BEFORE IT CHANGES TO
SNOW BY MIDNIGHT. IT IS ALSO NOT OUT OF THE QUESTION FOR A BRIEF
PERIOD OF FREEZING RAIN TO FALL AT ONSET IN THE BUREAU/PUTNAM
COUNTY AREA. HOWEVER...IF THIS WOULD OCCUR...THE EVAPORATIVE
COOLING WOULD QUICKLY CHANGE IT TO SLEET. AND WITH THE WARM
TEMPERATURES THESE LAST FEW DAYS...ONLY ELEVATED SURFACES SHOULD
BE AT RISK FOR FREEZING.
IN TERMS OF SNOW AMOUNTS...THE GARCIA METHOD WOULD SUGGEST 2-4 INCHES
IN THE HEAVIEST BAND FROM THE QUAD CITIES NORTHEASTWARD. THE MODEL TIME
SECTIONS DO SUPPORT THIS...SHOWING POTENTIAL FOR DENDRITIC GROWTH
IN THAT SAME AREA. WHILE DENDRITES WOULD INCREASE AMOUNTS...THE SHORT
DURATION OF THE EVENT AND ANY SLEET AT ONSET WILL LIMIT THE
ACCUMULATIONS.
THE BOTTOM LINE IS THAT I EXPECT A SHARP CUT-OFF IN SNOW ACCUMULATIONS
SOMEWHERE IN THE VICINITY OF THE 380 CORRIDOR...THE HEAVIEST SNOW
AMOUNTS IN THE 2-4 INCH RANGE FROM NEAR THE QUAD CITIES NORTHEASTWARD
TO FREEPORT...AND A LONGER PERIOD OF SLEET WITH LESSER SNOW
ACCUMULATIONS AS YOU MOVE TOWARD THE PRINCETON ILLINOIS AREA. THE
MAIN PRECIP EVENT WILL BEGIN AFTER 6 PM TONIGHT...CHANGING TO SNOW
AREA WIDE BY MIDNIGHT AND SHOULD HAVE EXITED ALL BUT THE EXTREME
EASTERN PORTIONS OF THE CWFA BY 6 AM.
DMD
LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...
SUNDAY NIGHT AND MONDAY...LATEST 12Z RUN MODELS IN GOOD AGREEMENT OF
SUGGESTING SFC RIDGING SLIDING ACRS THE REGION FROM THE WEST SUNDAY
NIGHT...WHILE CONFLUENT FLOW REGION WEST OF L/W TROF TRYING TO
PHASE ACRS THE EASTERN ROCKIES. EXPECT CLEARING SKIES AS HIGH CLOUDS
NORTHWEST OF LLVL BAROCLINIC REGION PUSH EASTWARD...COMBINED WITH
DECREASING WINDS FOR A COLD NIGHT OVER FRESH SNOW COVER. SOME SINGLE
DIGITS POSSIBLE BY EARLY MON MORNING. MAINLY CLEAR SKIES AND COLD
CONDITIONS TO FINISH OUT THE PERIOD WITH HIGHS IN THE 20S MON AND
SINGLE DIGITS TO LOWER TEENS MON NIGHT. SOME LIGHT RETURN FLOW MAY
MAKE FOR NON-DIURNAL TEMP TRENDS PRE-DAWN EARLY TUE MORNING WEST OF
THE MS RVR.
TUESDAY AND WEDNESDAY...LATEST RUN MEDIUM RANGE SOLUTIONS SUGGEST
THE ABOVE MENTIONED LONG WAVE TROF AXIS WILL SHEAR ACRS THE MID
CONUS THIS PERIOD FROM THE GRT LKS...ALL THE WAY TO THE BAJA OF MEX.
UPPER RIDGE ALONG AND JUST OFF THE WEST COAST AMPLIFIES...EVENTUALLY
DUMPING RIDGE-RIDING WAVE ENERGY DOWN ACRS THE UPPER MIDWEST AND GRT
LKS THROUGH MID WEEK. HOW FAR SOUTH THIS CLIPPER TYPE WAVE WILL
EVENTUALLY DIG IS STILL SOMEWHAT UNCERTAIN...ALL LONGER RANGE MODEL
SOLUTIONS BUT THE 12Z GFS KEEP LEAD WAVE AND IT/S ASSOCIATED PRECIP
TO THE NORTH OF THE AREA UNTIL MAYBE WED NIGHT WHEN SOME FLURRIES
MAKE IT ACRS THE NORTHEASTERN THIRD OF THE AREA/CWA UNDER RE-
ENFORCING CYCLONIC FLOW DIGGING ACRS THE SOUTHWESTERN GRT LKS. THE
12Z GFS IS MORE PROGRESSIVE AND DEEPER SOUTH WITH THE CLIPPER AND
PRODUCES LIGHT SNOW ACRS MOST OF THE LOCAL AREA TUE NIGHT INTO WED
MORNING BEFORE SHUTTLING QUICKLY OFF TO THE EAST. FOR NOW WILL SIDE
WITH THE MAJORITY AND KEEP THE FCST DRY...WITH THERMAL MODERATION
FROM THE SOUTHWEST AHEAD OF THE NORTHERN STREAM CLIPPER. HIGHS TUE
NEAR 30...MAY TRANSLATE INTO THE 30S BY WED BEFORE COLD FRONT OFF
THE PASSING CLIPPER SYSTEM TO THE NORTH SWEEPS THROUGH THE CWA BY
LATE WED.
THURSDAY THROUGH SATURDAY...LATEST RUN MEDIUM RANGE MODEL SOLUTIONS
AND ENSEMBLES GENERALLY SUGGEST WHILE A TYPE OF REX BLOCK SETS UP
ACRS THE WEST COAST AND SOUTHWESTERN U.S...BROAD UPPER LEVEL
TROFFINESS SETS UP ACRS MUCH OF THE EASTERN CONUS SOUTH OF NORTHERN
HUDSON BAY POLAR VORTEX. A RIBBON OF LLVL BAROCLINICITY SETS UP
PARALLEL TO THIS FEATURE FROM SOUTH CENTRAL CANADA...TO THE MID
ATLANTIC WHILE A BUILDING DOME OF VERY COLD AIRMASS LOOMS ACRS THE
EASTERN TWO THIRDS OF CANADA. WHILE THE REAL COLD AIR REMAINS BOTTLED
UP BY THIS PATTERN...WILL CONTINUE TO ADVERTISE MODERATING TEMPS
THROUGH SAT. DRY CONDITIONS TOO AS ANY IMPULSES WILL LOOK TO RIPPLE
ALONG THE BAROCLINIC RIBBON AND PRODUCE PRECIP MAINLY OT THE NORTH
ACRS THE DAKOTAS...MN...WI AND THE NORTH HALF OF THE GRT LKS INTO
SAT NIGHT. SOME LONGER RANGE SIGNS OF PLUNGING JET ENERGY TO ALLOW
SOME OF THE ARCTIC AIR TO BREAK LOOSE AND SPILL ACRS THE WESTERN
GRT LKS BY EARLY NEXT WEEK. ..12..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR CLINTON-DES
MOINES-JACKSON-LEE-LOUISA-MUSCATINE-SCOTT.
IL...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR BUREAU-CARROLL-
HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-MERCER-
PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE.
MO...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR CLARK.
&&
$$
LE
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
603 PM CST SAT JAN 12 2013
.UPDATE...
AN UPDATE WILL BE OUT SHORTLY FOR SOME FAIRLY MINOR TWEAKS TO THE
FORECAST...AND AN INFUSION OF THE RECENT DATA.
&&
.AVIATION...
SOME SNOW AND SLEET WILL OVERSPREAD THE AREA THIS EVENING. SITES
ALONG AND EAST OF THE MISSISSIPPI RIVER COULD SEE A BRIEF PERIOD
OF SLEET AT ONSET WHICH WILL RAPIDLY CHANGE OVER TO SNOW. KBRL AND
KMLI ARE MOST LIKELY TO SEE THIS PERIOD OF SLEET. KCID AND KDBQ
WILL RECEIVE ALL SNOW...AND WILL HAVE A SHORTER PERIOD OF
PRECIPITATION THAN KMLI AND KBRL. CIGS AND VSBYS ARE EXPECTED TO BE
PREDOMINANTELY MVFR...WITH SOME POTENTIAL FOR IFR CIGS AND VSBYS
IN THE HEAVIEST PRECIPITATION. SNOWFALL RATES WILL BE MOST
INTENSE BETWEEN 4Z AND 8Z OVERNIGHT. SNOW IS EXPECTED TO END BY
12Z. A RETURN TO VFR CONDITIONS IS EXPECTED AFTER.
LE
&&
.PREV DISCUSSION... /ISSUED 303 PM CST SAT JAN 12 2013/
SYNOPSIS...
COLD FRONT PUSHING INTO THE OHIO VALLEY THIS AFTERNOON...WITH COLD
AIR OOZING INTO THE UPPER MISSISSIPPI VALLEY BEHIND IT. LONG WAVE
TROUGH SPANNING THE ROCKIES...WITH ENERGY LIFTING OUT OVER THE
CENTRAL US IN FAST SOUTHWEST FLOW. LEAD SHORTWAVE GENERATING SOME
SNOW/SLEET OVER NORTHERN MO AND INTO SE IA AT THIS TIME. MAIN
PRECIP AREA ACROSS SOUTHERN MO AND SOUTHERN ILLINOIS IS ALSO
EXPANDING NORTHWARD AND IS NOW PUSHING INTO CENTRAL ILLINOIS AHEAD
OF THE MAIN SHORT WAVE...WHICH CAN BE SEEN ON SATELLITE LIFTING OUT
OF ARKANSAS.
SHORT TERM...TONIGHT AND SUNDAY...
MAIN FORECAST QUESTIONS THIS AFTERNOON CENTER AROUND DEVELOPING
PRECIPITATION EVENT FOR TONIGHT. THE INITIAL WAVE OF LIGHT SNOW/SLEET
NOW MOVING ACROSS EASTERN IA WILL HELP COOL AND SATURATE THE COLUMN
AHEAD OF TONIGHTS WAVE BUT WILL HAVE LITTLE OTHER IMPACT. FOR TONIGHT...OF
THE SHORT RANGE MODELS...THE RAP IS THE MOST AGGRESSIVE WITH
SNOWFALL AMOUNTS...SUGGESTING 4 TO 6 INCHES ALONG AND EAST OF THE
MISSISSIPPI RIVER. MEANWHILE...THE NAM...GFS...AND ECMWF ARE MORE
CONSERVATIVE WITH 2-3 INCHES AT MOST. THUS WILL FAVOR A BLEND OF
THE NAM AND ECMWF FOR THIS FORECAST...ESPECIALLY FOR MOISTURE PARAMETERS.
THERE IS CONSISTENCY IN THE FORECAST SOUNDINGS...SHOWING A LARGE
WEDGE OF WARM AIR ALOFT...ESPECIALLY EAST OF THE MISSISSIPPI
RIVER...THAT WILL HAVE TO COOL BEFORE PRECIP CHANGES TO SNOW.
CURRENT THINKING IS THAT NEAR THE RIVER THE PERIOD OF SLEET SHOULD
BE BRIEF...BUT WILL LAST LONGER AS YOU GO EAST. BUREAU/PUTNAM
COUNTIES COULD SEE A COUPLE OF HOURS OF SLEET BEFORE IT CHANGES TO
SNOW BY MIDNIGHT. IT IS ALSO NOT OUT OF THE QUESTION FOR A BRIEF
PERIOD OF FREEZING RAIN TO FALL AT ONSET IN THE BUREAU/PUTNAM
COUNTY AREA. HOWEVER...IF THIS WOULD OCCUR...THE EVAPORATIVE
COOLING WOULD QUICKLY CHANGE IT TO SLEET. AND WITH THE WARM
TEMPERATURES THESE LAST FEW DAYS...ONLY ELEVATED SURFACES SHOULD
BE AT RISK FOR FREEZING.
IN TERMS OF SNOW AMOUNTS...THE GARCIA METHOD WOULD SUGGEST 2-4 INCHES
IN THE HEAVIEST BAND FROM THE QUAD CITIES NORTHEASTWARD. THE MODEL TIME
SECTIONS DO SUPPORT THIS...SHOWING POTENTIAL FOR DENDRITIC GROWTH
IN THAT SAME AREA. WHILE DENDRITES WOULD INCREASE AMOUNTS...THE SHORT
DURATION OF THE EVENT AND ANY SLEET AT ONSET WILL LIMIT THE
ACCUMULATIONS.
THE BOTTOM LINE IS THAT I EXPECT A SHARP CUT-OFF IN SNOW ACCUMULATIONS
SOMEWHERE IN THE VICINITY OF THE 380 CORRIDOR...THE HEAVIEST SNOW
AMOUNTS IN THE 2-4 INCH RANGE FROM NEAR THE QUAD CITIES NORTHEASTWARD
TO FREEPORT...AND A LONGER PERIOD OF SLEET WITH LESSER SNOW
ACCUMULATIONS AS YOU MOVE TOWARD THE PRINCETON ILLINOIS AREA. THE
MAIN PRECIP EVENT WILL BEGIN AFTER 6 PM TONIGHT...CHANGING TO SNOW
AREA WIDE BY MIDNIGHT AND SHOULD HAVE EXITED ALL BUT THE EXTREME
EASTERN PORTIONS OF THE CWFA BY 6 AM.
DMD
LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...
SUNDAY NIGHT AND MONDAY...LATEST 12Z RUN MODELS IN GOOD AGREEMENT OF
SUGGESTING SFC RIDGING SLIDING ACRS THE REGION FROM THE WEST SUNDAY
NIGHT...WHILE CONFLUENT FLOW REGION WEST OF L/W TROF TRYING TO
PHASE ACRS THE EASTERN ROCKIES. EXPECT CLEARING SKIES AS HIGH CLOUDS
NORTHWEST OF LLVL BAROCLINIC REGION PUSH EASTWARD...COMBINED WITH
DECREASING WINDS FOR A COLD NIGHT OVER FRESH SNOW COVER. SOME SINGLE
DIGITS POSSIBLE BY EARLY MON MORNING. MAINLY CLEAR SKIES AND COLD
CONDITIONS TO FINISH OUT THE PERIOD WITH HIGHS IN THE 20S MON AND
SINGLE DIGITS TO LOWER TEENS MON NIGHT. SOME LIGHT RETURN FLOW MAY
MAKE FOR NON-DIURNAL TEMP TRENDS PRE-DAWN EARLY TUE MORNING WEST OF
THE MS RVR.
TUESDAY AND WEDNESDAY...LATEST RUN MEDIUM RANGE SOLUTIONS SUGGEST
THE ABOVE MENTIONED LONG WAVE TROF AXIS WILL SHEAR ACRS THE MID
CONUS THIS PERIOD FROM THE GRT LKS...ALL THE WAY TO THE BAJA OF MEX.
UPPER RIDGE ALONG AND JUST OFF THE WEST COAST AMPLIFIES...EVENTUALLY
DUMPING RIDGE-RIDING WAVE ENERGY DOWN ACRS THE UPPER MIDWEST AND GRT
LKS THROUGH MID WEEK. HOW FAR SOUTH THIS CLIPPER TYPE WAVE WILL
EVENTUALLY DIG IS STILL SOMEWHAT UNCERTAIN...ALL LONGER RANGE MODEL
SOLUTIONS BUT THE 12Z GFS KEEP LEAD WAVE AND IT/S ASSOCIATED PRECIP
TO THE NORTH OF THE AREA UNTIL MAYBE WED NIGHT WHEN SOME FLURRIES
MAKE IT ACRS THE NORTHEASTERN THIRD OF THE AREA/CWA UNDER RE-
ENFORCING CYCLONIC FLOW DIGGING ACRS THE SOUTHWESTERN GRT LKS. THE
12Z GFS IS MORE PROGRESSIVE AND DEEPER SOUTH WITH THE CLIPPER AND
PRODUCES LIGHT SNOW ACRS MOST OF THE LOCAL AREA TUE NIGHT INTO WED
MORNING BEFORE SHUTTLING QUICKLY OFF TO THE EAST. FOR NOW WILL SIDE
WITH THE MAJORITY AND KEEP THE FCST DRY...WITH THERMAL MODERATION
FROM THE SOUTHWEST AHEAD OF THE NORTHERN STREAM CLIPPER. HIGHS TUE
NEAR 30...MAY TRANSLATE INTO THE 30S BY WED BEFORE COLD FRONT OFF
THE PASSING CLIPPER SYSTEM TO THE NORTH SWEEPS THROUGH THE CWA BY
LATE WED.
THURSDAY THROUGH SATURDAY...LATEST RUN MEDIUM RANGE MODEL SOLUTIONS
AND ENSEMBLES GENERALLY SUGGEST WHILE A TYPE OF REX BLOCK SETS UP
ACRS THE WEST COAST AND SOUTHWESTERN U.S...BROAD UPPER LEVEL
TROFFINESS SETS UP ACRS MUCH OF THE EASTERN CONUS SOUTH OF NORTHERN
HUDSON BAY POLAR VORTEX. A RIBBON OF LLVL BAROCLINICITY SETS UP
PARALLEL TO THIS FEATURE FROM SOUTH CENTRAL CANADA...TO THE MID
ATLANTIC WHILE A BUILDING DOME OF VERY COLD AIRMASS LOOMS ACRS THE
EASTERN TWO THIRDS OF CANADA. WHILE THE REAL COLD AIR REMAINS BOTTLED
UP BY THIS PATTERN...WILL CONTINUE TO ADVERTISE MODERATING TEMPS
THROUGH SAT. DRY CONDITIONS TOO AS ANY IMPULSES WILL LOOK TO RIPPLE
ALONG THE BAROCLINIC RIBBON AND PRODUCE PRECIP MAINLY OT THE NORTH
ACRS THE DAKOTAS...MN...WI AND THE NORTH HALF OF THE GRT LKS INTO
SAT NIGHT. SOME LONGER RANGE SIGNS OF PLUNGING JET ENERGY TO ALLOW
SOME OF THE ARCTIC AIR TO BREAK LOOSE AND SPILL ACRS THE WESTERN
GRT LKS BY EARLY NEXT WEEK. ..12..
AVIATION...
A WINTRY MIX WILL OVERSPREAD THE AREA THIS EVENING. SITES ALONG
AND WEST OF THE MISSISSIPPI RIVER COULD SEE A BRIEF PERIOD OF
SLEET AT ONSET WHICH WILL RAPIDLY CHANGE OVER TO SNOW. EAST OF THE
MISSISSIPPI RIVER...ROUGHLY FROM PRINCETON IL TO MACOMB
IL...PRECIPITATION IS EXPECTED TO BEGIN WITH A BRIEF PERIOD OF
FREEZING RAIN EARLY THIS EVENING...CHANGING TO SLEET FOR SEVERAL
HOURS...AND THEN FINALLY OVER TO SNOW AROUND MIDNIGHT. AREA
WIDE... SNOWFALL RATES WILL BE MOST INTENSE BETWEEN 3Z AND 9Z
OVERNIGHT... AND SNOW IS EXPECTED TO END BY 12Z. OTHERWISE... BY
02Z LOOK FOR PREDOMINANTLY MVFR CIGS AND VSBYS WITH LOCAL IFR IN
HEAVIER PRECIPITATION.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR CLINTON-DES
MOINES-JACKSON-LEE-LOUISA-MUSCATINE-SCOTT.
IL...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR BUREAU-CARROLL-
HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-MERCER-
PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE.
MO...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR CLARK.
&&
$$
LE
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
302 PM CST FRI JAN 11 2013
.SYNOPSIS...
12Z UA ANALYSIS HAS A STRONG SYSTEM OVER THE ROCKIES WITH STRONG
SOUTHWEST FLOW FROM NORTHERN MEXICO INTO THE GREAT LAKES.
SATELLITE TRENDS THROUGH MID AFTERNOON INDICATE THE LOW CLOUDS ARE
BREAKING UP AS DEEPER MIXING OCCURS BUT MID AND HIGH LEVEL CLOUDS
ARE STREAMING IN OVER THE REMAINING LOW CLOUDS.
18Z SFC ANALYSIS HAS A LOW NORTH OF KATY WITH ANOTHER NORTHEAST OF
KLIC. A STRONG COLD FRONT CONNECTED BOTH LOWS AND THERE WERE
NUMEROUS TROFS FROM THE GREAT LAKES BACK INTO THE SOUTHERN PLAINS.
DEW POINTS WERE IN THE TEENS AND 20S ACROSS THE NORTHERN PLAINS
WITH 30S AND 40S ACROSS MUCH OF THE GREAT LAKES AND MIDWEST. DEW
POINTS IN THE 50S AND 60S RAN FROM THE OHIO VALLEY INTO THE DEEP
SOUTH.
&&
.SHORT TERM...LATE THIS AFTERNOON THROUGH SATURDAY
WE ARE DEALING WITH ADVECTION FOG. IN ADVECTION FOG YOU CAN HAVE
EXTREMELY DENSE FOG EVEN THOUGH WINDS ARE 10 TO 20 MPH. ALBEIT FAR
FROM PERFECT...THE RAP MODEL TRENDS STRONGLY POINT TO DENSE FOG
CONTINUING INTO THE EVENING ACROSS THE NORTHERN CWFA.
AS FOR HEADLINES...THE DENSE FOG ADVISORY WILL BE EXTENDED UNTIL
MIDNIGHT FROM DUBUQUE ON WEST IN THE HWY 20 CORRIDOR. PER
OBSERVATIONS AND WHAT WEB CAMS ARE AVAILABLE...THE NORTHERN PARTS
OF LINN/JONES/JACKSON COUNTIES IN IOWA AND STEPHENSON COUNTY IN
ILLINOIS STILL HAVE DENSE FOG OVER THEM. THUS THESE COUNTIES AND
JO DAVIESS COUNTY WILL HAVE THE DENSE FOG ADVISORY EXTENDED
THROUGH 6 PM.
THE POSSIBILITY DOES EXIST THAT THE HEADLINES MAY BE DROPPED
EARLY. THAT WILL DEPEND UPON STRONGER WINDS PROMOTING MIXING OF
THE BOUNDARY LAYER TO CAUSE THE FOG TO LIFT.
AFTER MIDNIGHT...A STRONG COLD FRONT WILL SWEEP THROUGH THE CWFA.
THIS FRONT WILL SCOUR OUT WHAT REMAINING FOG IS ACROSS THE AREA.
VERY BRISK CONDITIONS WILL BE SEEN ACROSS THE AREA ON SATURDAY
BEHIND THE FRONT.
THE STRENGTH OF THE CAA ON SATURDAY WOULD NORMALLY RESULT IN
UNSTABLE CONDITIONS WITH CONVECTIVE SHOWERS DEVELOPING. HOWEVER...
LOW LEVEL LAPSE RATES REMAIN QUITE STABLE DURING THE DAY AND FCST
SOUNDINGS SHOW A VERY PRONOUNCED INVERSION ACROSS THE AREA. THUS
SATURDAY WILL REMAIN DRY.
LOW TEMPERATURES TONIGHT WILL OCCUR AROUND 8 AM SATURDAY. THE HIGH
TEMPERATURES FOR THE DAYLIGHT HOURS ON SATURDAY WILL OCCUR BETWEEN
8 AND 10 AM FOLLOWED BY SLOWLY FALLING TEMPERATURES. TEMPERATURES
MAY REBOUND A LITTLE DURING THE AFTERNOON BUT WILL BE BELOW THE
MORNING HIGHS. ..08..
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
SATURDAY NIGHT AND SUNDAY TO BE THE TRICKY PERIOD. LAST NIGHT THE
ECMWF TOOK A JOG TO THE NORTHWEST WITH A SHORTWAVE AND SURFACE
LOW THAT MOVES FROM EAST TEXAS NORTHEAST UP THE OHIO VALLEY. IT
APPEARS TO BE BRINGING THE WHOLE FEATURE FARTHER NORTHWEST...AS
WELL AS TAKING ADVANTAGE OF SOME DEEPER FRONTOGENESIS THAT SEEMS
TO BE FORMING ON THE NORTH SIDE OF THE FEATURE. THIS
MORNING...MORE OF THE MODELS FOLLOWED THAT TREND...AND ARE NOW
BRINGING A NICE SWATH OF SNOW TO THE FORECAST AREA. AREAS
SOUTHEAST OF A LINE FROM CEDAR RAPIDS TO DUBUQUE ARE NOW LOOKING
AT A NICE 1 TO POSSIBLY 3 INCH SNOWFALL EVENT...ASSUMING WE CAN
GET ENOUGH MOISTURE INTO THE AREA AND THE ECMWF AND GFS
ISENTROPIC AND FRONTOGENESIS LIFT PROGS ARE CORRECT. HAVE RAISED
POPS...BUT IF THIS TREND CONTINUES WITH TONIGHTS MODEL RUNS...WE
COULD RAISE POPS AGAIN.
SUNDAY NIGHT AND MONDAY TO BE COLD...ESPECIALLY IF WE CAN GET
SOME SNOW ON THE GROUND TO ENHANCE THE STRONG SURFACE RIDGE THAT
WILL BE SITTING OVER THE AREA BY EARLY MONDAY MORNING. AT THIS
TIME IT LOOKS LIKE WE MAY SEE SOME SINGLE DIGITS IN THE NORTHWEST
PORTIONS OF THE FORECAST AREA. IF WE DO GET THE NEW
SNOWPACK...NEARLY THE WHOLE CWA COULD HAVE SINGLE DIGIT MINS WITH
NEAR ZERO VALUES POSSIBLE NORTHWEST. HIGHS ON MONDAY TO STILL BE
CHILLY WITH THE RIDGE STILL OVERHEAD...AND CURRENTLY HAVE MID TO
UPPER 20S.
TUESDAY THE MAIN UPPER LEVEL TROUGH TO SLOWLY MOVE
OVERHEAD...INCREASING CLOUD COVER SOMEWHAT AND WITH SOME WEAK
WARM AIR ADVECTION BEGINNING ALOFT SOME MODERATION OF TEMPERATURES
IS POSSIBLE.
WEDNESDAY A STRONG CLIPPER IS LIKELY TO MOVE OUT OF CANADA IN THE
LONGWAVE TROUGH. THIS SYSTEM TO STAY MOSTLY NORTH OF THE
AREA...BUT IT WILL PULL SOME WARMER TEMPERATURES ALOFT OVER THE
AREA...FOR A CONTINUATION OF THE WARMING TREND STARTED ON TUESDAY.
HIGHS WEDNESDAY AFTERNOON SHOULD BE IN THE 30S NEARLY EVERYWHERE.
WITH THE CLIPPER NOW HAVING MOVED OFF TO THE EAST BY WEDNESDAY
NIGHT...A FRESH SHOT OF COLDER AIR WILL MOVE INTO THE CWA FROM
THE NORTH AS THE UPPER LEVEL TROUGH AXIS SHARPENS. IT LOOKS LIKE A
SHORTWAVE MAY DIVE THROUGH THE AREA THURSDAY...BUT SOME MODELS
KEEP IT TOO FAR NORTH TO AFFECT THE AREA...SO HAVE LEFT FORECAST
DRY FOR NOW. FRIDAY LOOKS COLD AND DRY AS WELL.
LE
&&
.AVIATION...
CONDITIONS HAVE IMPROVED TO VFR AT KBRL/KMLI AND ARE NOW EXPECTED
TO REMAIN THAT WAY THROUGH 00Z/13. KCID IS EXPECTED TO IMPROVE TO
VFR AROUND 00Z/12. KDBQ WILL REMAIN BELOW MINIMUMS DUE TO
ADVECTION FOG THROUGH 03Z/12. THE RAP MODEL IS NOW SUGGESTING KDBQ
WILL BEGIN IMPROVING AFT 03Z/12 WITH MVFR CONDITIONS DEVELOPING. A
STRONG COLD FRONT WILL MOVE THROUGH EASTERN IOWA AND NORTHERN
ILLINOIS AFT 06Z/12. CONDITIONS ARE EXPECTED TO IMPROVE TO VFR AT
ALL TAF SITES WITH FRONTAL PASSAGE. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...DENSE FOG ADVISORY UNTIL 6 PM CST THIS EVENING FOR JACKSON-JONES-
LINN.
DENSE FOG ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BUCHANAN-
DELAWARE-DUBUQUE.
IL...DENSE FOG ADVISORY UNTIL 6 PM CST THIS EVENING FOR JO DAVIESS-
STEPHENSON.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
315 AM CST FRI JAN 11 2013
.SHORT TERM /TODAY/...
THE UPPER LEVEL LOW THAT WAS MOVING NORTHEAST ACROSS MISSOURI WILL
BE IN THE GREAT LAKES REGION LATER THIS MORNING. A LONG WAVE TROUGH
WILL SET UP OVER THE INTERMOUNTAIN WEST PROVIDING A DEEP SOUTHWEST
FLOW ALOFT OVER IOWA. IN ADDITION A SURFACE LOW WILL SET UP JUST TO THE
WEST OF IOWA. THE GRADIENT WILL TIGHTEN OVER CENTRAL IOWA LATER
THIS MORNING AND ESPECIALLY THIS AFTERNOON AND CREATE BREEZY
CONDITIONS AS THE SOUTHERLY FLOW ALSO ADVECTS IN SOME VERY WARM
TEMPERATURES TODAY.
SOMEWHAT PROBLEMATIC TODAY IS THE CURRENT FOG STRATUS AND DRIZZLE
SITUATION. THE SOUPY AIRMASS WILL HANG OVER THE FORECAST AREA THIS
MORNING AND AS THE WARMER AIR MOVES IN IT WILL CREATE AN INVERSION
OVER THE CWA THAT WILL BE VERY TOUGH TO BREAK BASED ON FORECAST
SOUNDINGS. IT DOES NOT LOOK LIKE THE INVERSION WILL BREAK DUE TO
MIXING THUS I AM KEEPING THE MENTION OF FOG AROUND A LITTLE LONGER
THAN THE PREVIOUS FORECAST HAD IT. HOWEVER SOUNDINGS DO INDICATE WE
MAY HAVE MORE OF A CEILING ISSUE. AS THE WINDS INCREASE LATE
MORNING THE FOG WILL THIN AND VISIBILITIES SHOULD IMPROVE
SOME...CERTAINLY ABOVE DENSE FOG CRITERIA AND WHILE CEILINGS WILL
LIFT I DO NOT SEE MUCH CHANCE OF THE FORECAST AREA BREAKING OUT
UNTIL LATE AFTERNOON AT THE EARLIEST WHEN THE SURFACE LOW SHIFTS
NORTHEAST AND BEGINS TO DRAG A COLD FRONT INTO THE AREA.
AS FOR TEMPS...COULD SEE SOME RECORD HIGHS TODAY ACROSS THE SOUTH.
THIS IS ESPECIALLY TRUE IN AREAS WITH NO SNOW COVER.
.LONG TERM /TONIGHT THROUGH THURSDAY/...
MAIN CHALLENGES THIS PERIOD WILL BE TEMPERATURES FOR THE WEEKEND AND
EARLY NEXT WEEK. SOME CONSENSUS ON THE TIMING OF THE COLD AIR BEHIND
THE BOUNDARY TONIGHT AND TOMORROW AS THE COLD AIR LOOKS TO LAG THE
BOUNDARY OVER CENTRAL AND SOUTHEAST IOWA BY ABOUT 6 TO 12 HOURS.
OTHERWISE IT SHOULD SETTLE INTO NORTHWEST AREAS THE QUICKEST. HAVE
TRIMMED THE TEMPS OVER THE NORTHWEST FOR BOTH AM LOWS SAT AND HIGHS
DURING THE AFTERNOON HOURS. THERE MIGHT BE SOME LEFT OVER PATCHY FOG
AND LIGHT DRIZZLE FAR NORTH THIS EVENING BEFORE THE FRONT SWEEPS
THROUGH. FOR THE REMAINDER OF SATURDAY MUCH OF THE FORECAST AREA
WILL BE BETWEEN THE DEPARTING NORTHERN STREAM LOW AND A SOUTHERN
STREAM LOW TRACKING THROUGH THE MID MISSISSIPPI RIVER VALLEY.
PREVIOUS RUNS OF ALL MED RANGE MODELS MAINTAINED A SOUTHERLY TRACK
AWAY FROM OUR AREA...BUT TONIGHTS 00Z EURO HAS NOW BACKED THE DEF
ZONE MUCH FARTHER NORTHWEST INTO SOUTHEAST IOWA AND BROUGHT NORTH
ABOUT .25 INCHES OF QPF OVER THE FAR SOUTHEAST SAT EVENING AND
OVERNIGHT INTO EARLY SUNDAY MORNING. THIS WOULD RESULT IN NEARLY A 2
TO 4 INCH BAND SOUTHEAST OF A LINE NEAR LAMONI TO ABOUT OTTUMWA WITH
JUST A DUSTING AS FAR NORTHWEST AS DES MOINES. THIS DEPARTURE NEEDS
SOME MONITORING AS IT MIGHT END UP BEING ACCUMULATING SNOWFALL THERE
AND TO THE EAST OF OUR FORECAST AREA IN EASTERN IOWA. FOR NOW WILL
NOT ADJUST TOO MUCH GIVEN THIS IS THE ONLY MODEL THAT FAR NORTHWEST
...BUT THE GEM IS ALSO TRENDING NORTHWEST A BIT. AFTER THE PASSAGE
OF THIS SYSTEM THE COLD AIR SETTLES ACROSS THE AREA WITH HIGH
PRESSURE ANCHORED OVER THE STATE FOR A FEW DAYS. BY LATE MONDAY THE
PATTERN SHIFTS TO A MORE ZONAL FLOW WITH ADIABATIC WARMING
COMMENCING AGAIN ACROSS THE PLAINS. THIS WILL END THE PROGRESSION OF
COLD AIR FOR NOW...WITH A WARM UP ON THE WAY BY MID WEEK. WITH LESS
SNOW COVER AND H850 TEMPS REACHING 2 TO 4C BY WED AFTERNOON...SHOULD
EASILY SEE MID TO UPPER 30S OVER THE AREA WITH LOWER 40S POSSIBLE IN
THE SOUTH. SINCE TRENDS HAVE NOT SHOWN GREAT CONSENSUS WILL USE THE
BLEND APPROACH. MILD WEATHER SLATED TO STICK AROUND FOR ABOUT 3 DAYS
BEFORE AN ARCTIC AIRMASS MAKES AN ATTEMPT TO CRASH SOUTHEAST BY
FRIDAY. PLENTY OF WRINKLES IN THE PATTERN CHANGE...IF ANY...SO WILL
HAVE TO MONITOR.
&&
.AVIATION...11/06Z
LIFR VIS AND CIGS WILL CONTINUE THROUGH THE NEXT FORECAST
PACKAGE...WITH CONDITIONS SLOWLY IMPROVING B/T 13-15Z FRIDAY
MORNING. THE LATEST HRRR MODEL RUN KEEPS LIFR/IFR CONDITIONS THROUGH
16Z ACROSS MUCH OF CENTRAL IOWA. FOR NOW...HAVE A SLOW TRANSITION TO
MVFR BY 18Z AS WAA INCREASES WITH THE TIGHT PRESSURE GRADIENT AHEAD
OF COLD FRONT. POTENTIAL TO HAVE MVFR STRATUS DECK PERSIST UNTIL THE
COLD FRONT SWEEPS ACROSS THE STATE PAST 06Z SATURDAY AND WAS
CONFIDENT ENOUGH TO KEEP MVFR CIGS AT ALO/FOD/MCW THROUGH FRIDAY
NIGHT.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY THROUGH 9 AM CST FRIDAY FOR ADAIR-ADAMS-
APPANOOSE-AUDUBON-CASS-CLARKE-DALLAS-DAVIS-DECATUR-GUTHRIE-
JASPER-LUCAS-MADISON-MAHASKA-MARION-MONROE-POLK-POWESHIEK
-RINGGOLD-TAYLOR-UNION-WAPELLO-WARREN-WAYNE.
DENSE FOG ADVISORY THROUGH NOON CST FRIDAY FOR BLACK HAWK-BOONE
-BREMER-BUTLER-CALHOUN-CARROLL-CERRO GORDO-CRAWFORD-EMMET-
FRANKLIN-GREENE-GRUNDY-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-
KOSSUTH-MARSHALL-PALO ALTO-POCAHONTAS-SAC-STORY-TAMA-WEBSTER
-WINNEBAGO-WORTH-WRIGHT.
&&
$$
SHORT TERM...FAB
LONG TERM...REV
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1149 PM CST THU JAN 10 2013
.AVIATION...
LIFR AND IFR CONDITIONS TO PREVAIL ALL TERMINALS THROUGH AT LEAST
11/14Z. WARM MOIST AIR WITH AREAS OF LIGHT TO MODERATE DRIZZLE
WITH FOG WILL MOVE NORTH AS A SHORT WAVE PASSES LATE TONIGHT.
EXTENDED PERIODS OF CIGS AOB 500 FT AND VISIBILITY AOB 1 MILE WITH
DRIZZLE AND FOG CAN BE EXPECTED INTO LATE MORNING FRIDAY. ALL
TERMINALS MAY EXPERIENCE PERIODS BELOW AIRPORT MINIMUMS...LASTING
INTO THE MID MORNING HOURS. SOUTHEAST WINDS OF 5 TO 15 KTS WILL
SHIFT TO THE SOUTH AND SOUTHWEST FRIDAY. THE BRL AND MLI TERMINALS
WILL IMPROVE TO PROBABLY VFR CONDITIONS BY EARLY FRIDAY AFTERNOON
AS THE DISTURBANCE MOVES NORTHEAST AND MVFR CONDITIONS PROBABLE
AT CID/DBQ TERMINALS WHICH WILL BECOME VFR BY 12/00Z.
NICHOLS
&&
.PREV DISCUSSION... /ISSUED 319 PM CST THU JAN 10 2013/
SYNOPSIS...
12Z UA ANALYSIS HAS THE CUT OFF LOW IN WEST TEXAS WITH A 850MB
WARM FRONT RUNNING FROM CENTRAL OKLAHOMA INTO SOUTHEAST KANSAS. A
VERY SHARP 850MB MOISTURE GRADIENT RAN FROM NORTHWEST MISSOURI
INTO THE OHIO VALLEY. RADAR TRENDS THROUGH THE MORNING AND
AFTERNOON SHOW PLENTY OF VIRGA FROM NORTHERN IOWA INTO NORTHERN
ILLINOIS WITH SFC RAIN FROM SOUTHERN IOWA INTO CENTRAL ILLINOIS.
18Z SFC ANALYSIS HAS THE LOW IN SOUTHWEST OKLAHOMA WITH A
DEVELOPING BOUNDARY FROM CENTRAL OKLAHOMA TO NEAR KMEM. DEW POINTS
WERE IN THE 20S ACROSS THE GREAT LAKES WITH 30S AND 40S FROM THE
CENTRAL PLAINS INTO THE OHIO VALLEY. DEW POINTS IN THE 50S WERE IN
THE LOWER MISSISSIPPI VALLEY.
SHORT TERM...LATE THIS AFTERNOON AND TONIGHT
THE MOISTURE SURGE COMING UP FROM THE SOUTH IS STARTING TO WIN
OVER THE DRY AIR. SPOTTY RAIN OR DRIZZLE IS NOW OVER ROUGHLY THE
SOUTHERN HALF OF THE CWFA WITH SPRINKLES OR VERY SPOTTY RAIN
DEVELOPING OVER THE NORTHERN HALF.
RAP TRENDS INDICATE THAT A VERY RAPID TOP DOWN SATURATION WILL
OCCUR LATE THIS AFTERNOON. SO BY THE EVENING COMMUTE THERE SHOULD
BE FAIRLY WIDESPREAD VERY LIGHT RAIN OR DRIZZLE OCCURRING ACROSS
THE AREA.
TEMPERATURES WILL SLOWLY CLIMB LATE THIS AFTERNOON AS MOISTURE
CONTINUES TO SURGE INTO THE AREA. HIGH TEMPERATURES FOR THE
VERIFYING PERIOD WILL LIKELY OCCUR IN THE 6-8 PM TIME FRAME.
LIKEWISE...OVERNIGHT LOWS WILL LIKELY OCCUR IN THE 7-8 PM TIME
FRAME FOLLOWED BY STEADY OR SLOWLY RISING TEMPERATURES.
TONIGHT...STRONG FORCING MOVES ACROSS THE AREA DURING THE EVENING
WITH A FULLY SATURATED ATMOSPHERE. THE HEAVY RAIN TOOL SUGGESTS
THE EVENING HOURS WILL LIKELY ACCOUNT FOR MUCH OF THE RAINFALL
FROM THIS EVENT. AFTER MIDNIGHT...WIDESPREAD DRIZZLE WILL BE SEEN
BUT ANOTHER ROUND OF FORCING WILL LIKELY ALLOW SOME ADDITIONAL
RAIN TO OCCUR.
ANOTHER CONCERN TONIGHT IS FOG. THERE IS STILL A RESPECTABLE SNOW
FIELD OVER ROUGHLY THE NORTHERN THIRD OF THE CWFA. ADVECTING
MOISTURE INTO THE AREA ALONG WITH RAIN SHOULD ALLOW PATCHY OR SOME
AREAS OF FOG TO DEVELOP LATE THIS EVENING AS WINDS DIMINISH. AFTER
MIDNIGHT WINDS DROP OFF ACROSS THE NORTHWEST THIRD TO 40 PERCENT
OF THE CWFA WITH THE PASSAGE OF THE SFC LOW. AT THIS TIME THE RISK
FOR DENSE FOG WILL BE THE GREATEST.
THEREFORE...WILL ISSUE A DENSE FOG ADVISORY FOR THE MAIN SNOW
FIELD AND WHERE WINDS ARE PROGGED TO BE LIGHT. IT IS HIGHLY LIKELY
THAT THE DENSE FOG ADVISORY MAY HAVE TO BE EXPANDED DURING THE
EVENING OR OVERNIGHT HOURS. ..08..
LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...
HIGH TEMPERATURES FOR FRIDAY ARE A LARGE QUESTION MARK THIS
FORECAST. THE MAIN COMPLICATING FACTOR IS IN HOW QUICKLY THE LOW
CLOUDS CLEAR FROM SOUTH TO NORTH WITH THE ASSOCIATED CLEARING OF THE
FOG AND DRIZZLE. MODELS HAVE BEEN STRUGGLING WITH THIS ISSUE...WITH
MANY OF THEM KEEPING A TRAPPED LOWER LAYER OF LOW CLOUDS AND FOG
WITH A STRONG ELEVATED MIXED LAYER OVER THE TOP OF IT.
HOWEVER...THEY ALSO DEPICT STRONG SURFACE WINDS...WHICH DOES NOT
MATCH WELL WITH A TRAPPED LOW LEVEL INVERSION. A LOOK AT THE MODEL
INITIALIZATION SHOWS THAT NAM12 MODEL SNOW DEPTH INITIALIZATION IS
FAR TOO FAR SOUTH...WITH 1 INCH OR MORE OF SNOW DEPTH INTO NORTHERN
MISSOURI. GEM AND RUC ARE CLOSER TO REALITY. GFS MODEL SNOW DEPTH
INITIALIZATION MAY NOT BE ANY BETTER THAN THE NAM12...BUT CANNOT
CHECK ON THAT AT THIS TIME. THUS...HAVE DECIDED TO DEFINITELY ALLOW
THE CLOUDS TO CLEAR OUT OF THE SNOW FREE AREAS ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE FORECAST AREA...ALLOWING HIGH TEMPS TO GET
INTO THE MID TO UPPER 50S IN THE AFTERNOON. HOWEVER THE NORTH IS A
WHOLE SEPARATE CAN OF WORMS...WITH THE LOW CLOUDS FOG AND DRIZZLE
HANGING ON INTO THE AFTERNOON AND KEEPING TEMPERATURES IN THE 40S TO
NEAR 50 FOR THE MOST PART. THIS MAKES A LARGE RANGE ACROSS THE
FORECAST AREA IN MAX TEMPS...AND STILL LEAVES US WITH A LARGE BUST
POTENTIAL FOR THIS FORECAST. WITH THIS EXTRAORDINARY WARMTH...THE
RECORD HIGH TEMPERATURE FOR BURLINGTON IS AT RISK...AND WE WILL BE
CLOSE AT OTHER LOCATIONS. FOR REFERENCE...HAVE INCLUDED RECORD HIGHS FOR
FRIDAY BELOW.
OF COURSE...THIS IS NOT THE ONLY CONCERN THIS FORECAST. FRIDAY
NIGHT WILL BE MILD WITH TEMPERATURES REMAINING UP. IN
FACT...LOCATIONS ACROSS THE NORTH THAT DO NOT GET INTO THE SUNSHINE
WILL SLOWLY RISE INTO THE EVENING HOURS AND WILL REACH THEIR HIGH
TEMPERATURES IN THE LATE EVENING TO AROUND MIDNIGHT. THE STRONG
COLD FRONT COMES THROUGH EARLY SATURDAY MORNING AND TEMPERATURES
BEGIN TO FALL...WITH ONLY MINIMAL DIURNAL RISE IN THE AFTERNOON.
SATURDAY NIGHT AND SUNDAY THERE IS A WEAK SHORTWAVE THAT MOVES ALONG
A BAROCLINIC ZONE DRAPED FROM TEXAS UP THE OHIO RIVER VALLEY..WHICH
SHOULD PRODUCE A NICE BAND OF SNOW FOR AREAS NORTHWEST OF THE LOW
TRACK. THE TRICK IS WHETHER THIS SYSTEM WILL SHIFT FAR ENOUGH
NORTHWEST TO BRING SOME ACCUMULATING SNOWS TO THE FORECAST AREA
SATURDAY NIGHT AND EARLY SUNDAY. FOR NOW IT APPEARS THAT THE
SOUTHEAST PORTIONS OF THE AREA WILL GET SOME LIGHT SNOW
ACCUMULATIONS...BUT THE NORTHWEST EDGE OF THIS SNOW BAND WILL BE
FAIRLY SHARP...AND THE QUAD CITIES IS PROBABLY ONLY LOOKING SOME
PRETTY MINOR ACCUMULATIONS...DUSTING TO A HALF INCH PERHAPS.
BEHIND THIS SYSTEM WE ARE LOOKING AT GETTING SOME VERY COLD
TEMPERATURES INTO THE AREA...WITH 850MB TEMPS DROPPING TO AROUND
-10C BY MONDAY MORNING. AS LONG AS WE CLEAR OFF...TEMPERATURES WILL
DROP INTO THE TEENS. TEMPERATURES SHOULD SLOWLY MODERATE INTO
WEDNESDAY. ANOTHER LONGWAVE TROUGH IS EXPECTED TO MOVE THROUGH THE
AREA WEDNESDAY...BUT IT IS TOO DRY TO BRING MORE THAN A FRESH SHOT
OF COLDER AIR FOR THURSDAY.
LE
CLIMATE...
CORRECTED THESE RECORD HIGHS.
RECORD HIGHS FOR JANUARY 11...
MOLINE.........56 IN 2012
CEDAR RAPIDS...53 IN 2012
DUBUQUE........52 IN 2012
BURLINGTON.....55 IN 2012
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...DENSE FOG ADVISORY UNTIL 10 AM CST FRIDAY FOR BENTON-BUCHANAN-
DELAWARE-DUBUQUE-IOWA-JACKSON-JOHNSON-JONES-LINN.
IL...DENSE FOG ADVISORY UNTIL 10 AM CST FRIDAY FOR CARROLL-JO DAVIESS-
STEPHENSON.
MO...NONE.
&&
$$
NICHOLS
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1143 PM CST THU JAN 10 2013
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TONIGHT/...
LOW LEVEL MOISTURE FINALLY WORKING ITS WAY ACROSS THE CWA...WITH
LARGE AREA OF LIGHT RAIN LIFTING NORTHWARD THROUGH THE STATE.
ASSOCIATED UPPER LEVEL LOW CURRENTLY SPINNING OVER OKLAHOMA TO LIFT
NORTHEASTWARD INTO CENTRAL ILLINOIS BY 12Z FRIDAY. SOUTHERLY FLOW
AND STRONG WAA/MOISTURE ADVECTION TO CONTINUE ACROSS THE AREA THIS
EVENING...WITH MORE SOUTHWESTERLY FLOW BY LATE TONIGHT. NAM ALSO
SHOWING STEADY ISENTROPIC LIFT THROUGHOUT THE LOWEST FEW LAYERS
TONIGHT...THEREFORE EXPECT STEADIER LIGHT RAIN TO TRANSITION TO
DRIZZLE ACROSS MUCH OF THE AREA TONIGHT WITH SOUNDINGS ACROSS THE
CWA STILL SUGGESTING FAIRLY DEEP SATURATED LAYER. THEREFORE KEPT
POPS IN THE LIKELY TO CATEGORICAL RANGE OVERNIGHT AS EXPECT COULD
SEE A FEW HUNDREDTHS QPF WITH THE DRIZZLE. TEMPERATURES EXPECTED TO
REMAIN JUST ABOVE FREEZING ACROSS THE NORTH...THEREFORE HAVE STUCK
WITH DRIZZLE MENTION. SREF HINTED AT POSSIBILITY OF SFC TEMPS
DROPPING BELOW FREEZING FOR A FEW HOURS LATE TONIGHT NEAR MASON CITY
TO ESTHERVILLE. WILL HAVE TO MONITOR...BUT MOST OTHER MODELS KEEPING
SFC TEMPS ABOVE FREEZING WITH THE CLOUDS/PRECIP/FOG AND NEAR NEUTRAL
TO WAA...SO HAVE TRENDED TEMPERATURES TOWARD THE WARMER SOLUTIONS.
WITH THE ABUNDANCE OF MOISTURE IN THE NEAR SURFACE LAYERS...AND
ANTICIPATED SNOW MELT AS DEWPOINTS REMAIN ABOVE FREEZING OVERNIGHT
WITH THE LIGHT RAIN/DRIZZLE FOG DEVELOPMENT SEEMS QUITE CERTAIN.
ADDITIONALLY DENSE FOG ALSO POSSIBLE ACROSS ENTIRE CWA...ESPECIALLY
IN AREAS WITH DEEPER SNOWPACK. THEREFORE WILL ISSUE A DENSE FOG
ADVISORY FOR THE ENTIRE CWA FOR MAINLY LATE EVENING/LATE TONIGHT
INTO FRIDAY MORNING.
.LONG TERM /FRIDAY THROUGH THURSDAY/...
AS THE OVERNIGHT PRECIPITATION SYSTEM DEPARTS EAST OF THE MISSOURI
RIVER EARLY FRIDAY...A DEEPER LOW WILL DEVELOP EAST OF THE ROCKIES
AND SWING THROUGH NEBRASKA. NET EFFECT WILL BE INCREASING SOUTH FLOW
ACROSS IOWA FRIDAY...PROLONGING TRANSPORT OF LOW-LEVEL MOISTURE AND
WARMTH NORTH ACROSS SNOW PACK. AT MID AND UPPER LEVELS...A STRONG
DRY SLOT WILL SURGE NORTHEAST ACROSS IOWA. LOW CLOUDS/FOG/DRIZZLE
SHOULD BREAK UP FRIDAY MORNING FROM I-80 SOUTH...BUT IT IS LIKELY TO
LINGER ALL DAY THE FARTHER NORTH YOU GO. IT WILL BE VERY WARM IN
SOUTHERN IOWA...WHERE SNOW FREE AREAS SOUTH OF I-80 COULD APPROACH
OR EXCEED RECORDS WHICH ARE GENERALLY IN THE MIDDLE 50S. THE DENSE
FOG ADVISORY WILL CONTINUE THROUGH NOON...AND WE`LL SEE WHAT IS
NEEDED THEREAFTER. WITH THE COLD FRONT NOT SCHEDULED TO CROSS I-35
UNTIL ABOUT MIDNIGHT FRIDAY NIGHT...THERE IS A CHANCE THE FOG AND
SOME DRIZZLE COULD LINGER IN NORTHERN IOWA UNTIL THEN. THE GOOD NEWS
IS THAT TEMPERATURES WILL REMAIN ABOVE FREEZING UNTIL THE COLD AIR
HITS...WHICH WILL BE ACCOMPANIED BY DRYING AS WELL...SO NO FREEZING
PRECIPITATION EXPECTED.
TEMPERATURES WILL FALL RAPIDLY FRIDAY NIGHT AND NOT RECOVER MUCH ON
SATURDAY. MAY GET SOME LOW CLOUDS AND FLURRIES MIGHT BE POSSIBLE IN
THE FAR NORTHWEST...BUT DEEPER LIFT ZONE WILL TRACK WELL NORTH OF
IOWA. ALTHOUGH COLD AIR WILL SURGE IN AT LOW LEVELS...FLOW ALOFT
WILL REMAIN FROM THE SOUTHWEST. ON SATURDAY NIGHT...IOWA WILL BE ON
THE NORTH FRINGE OF A PRECIPITATION SYSTEM...BUT LIMITING
STREAMLINES LOOK LIKELY TO KEEP LIGHT SNOW CHANCE CONFINED TO THE
FAR SOUTHEAST OF THE FORECAST AREA.
FOR THE REST OF THE FORECAST...NO PRECIPITATION IS EXPECTED.
FLUCTUATING TEMPERATURES ARE LIKELY...AND CERTAINLY COOLER THAN THIS
WEEK...BUT NOT LOOKING EXTREME. GFS/ECMWF 12Z MODEL SOLUTIONS BEGIN
TO DIVERGE STARTING TUESDAY NIGHT. GFS IS FASTER AND GENERALLY
STRONGER WITH A COLD FRONT AND COLD SURGE THEN. FORECAST AT
THIS TIME SHOWS SOMETHING OF A MIDDLE OF THE ROAD FORECAST...BUT IT
APPEARS FORECAST RELIABILITY IS IFFY AS FAR AS AMOUNT OF COLD FOR
MID AND LATE NEXT WEEK. COLD POOL LOOKS LIKELY TO REMAIN OVER HUDSON
BAY WITH COLDER AIR OVER THE GREAT LAKES...WITH SOME INROADS INTO
IOWA.
&&
.AVIATION...11/06Z
LIFR VIS AND CIGS WILL CONTINUE THROUGH THE NEXT FORECAST
PACKAGE...WITH CONDITIONS SLOWLY IMPROVING B/T 13-15Z FRIDAY
MORNING. THE LATEST HRRR MODEL RUN KEEPS LIFR/IFR CONDITIONS THROUGH
16Z ACROSS MUCH OF CENTRAL IOWA. FOR NOW...HAVE A SLOW TRANSITION TO
MVFR BY 18Z AS WAA INCREASES WITH THE TIGHT PRESSURE GRADIENT AHEAD
OF COLD FRONT. POTENTIAL TO HAVE MVFR STRATUS DECK PERSIST UNTIL THE
COLD FRONT SWEEPS ACROSS THE STATE PAST 06Z SATURDAY AND WAS
CONFIDENT ENOUGH TO KEEP MVFR CIGS AT ALO/FOD/MCW THROUGH FRIDAY
NIGHT.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY FROM 9 PM THIS EVENING TO 9 AM CST FRIDAY FOR
ADAIR-ADAMS-APPANOOSE-AUDUBON-CASS-CLARKE-DALLAS-DAVIS-DECATUR-
GUTHRIE-JASPER-LUCAS-MADISON-MAHASKA-MARION-MONROE-POLK-POWESHIEK-
RINGGOLD-TAYLOR-UNION-WAPELLO-WARREN-WAYNE.
DENSE FOG ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST FRIDAY FOR
BLACK HAWK-BOONE-BREMER-BUTLER-CALHOUN-CARROLL-CERRO GORDO-
CRAWFORD-EMMET-FRANKLIN-GREENE-GRUNDY-HAMILTON-HANCOCK-HARDIN-
HUMBOLDT-KOSSUTH-MARSHALL-PALO ALTO-POCAHONTAS-SAC-STORY-TAMA-
WEBSTER-WINNEBAGO-WORTH-WRIGHT.
&&
$$
SHORT TERM...MJB
LONG TERM...JUNGBLUTH
AVIATION...KLP
AREA FORECAST DISCUSSION
NWS WICHITA KS
1101 AM CST FRI JAN 11 2013
.UPDATE...
THICK CIRRIFORM CLOUDS FOR THE TIME BEING HAVE LIMITED DIURNAL
TEMPERATURE RISE AND LIKEWISE MIXING/INCREASE IN SOUTH WINDS AS
WE APPROACH MIDDAY. THE LATEST RUC AND NAM WOULD SUGGEST WITH
AT LEAST PARTIAL CLEARING THAT STEEPER LAPSE RATES/BEST MIXING
POTENTIAL FOR WIND WILL ARRIVE TOWARD 21Z FOR A FEW HOURS INTO
THE LATE AFTERNOON ACROSS PORTIONS OF CENTRAL KANSAS. THEREFORE
WILL CONTINUE THE CURRENT WIND ADVISORY...THOUGH MORE LIKELY
REALIZING CRITERIA FOR THE LATTER PORTION OF THE HEADLINE PERIOD.
OTHERWISE ONLY SLIGHT ADJUSTMENT TO GRIDS BLENDING LATEST TRENDS
INTO THE AFTERNOON.
KED
&&
.AVIATION...18Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
VFR CONDITIONS EXPECTED TO PREVAIL THRU THE FORECAST VALID PERIOD.
GUSTY SOUTH TO SOUTHWEST WINDS WILL PREVAIL THRU THE AFTERNOON
HOURS AHEAD OF A PACIFIC TROF...WITH ITS PASSAGE EARLY THIS
EVENING FOLLOWED BY STRONGER POLAR COLD FRONT OVERNIGHT. THICK
VEIL OF MAINLY CIRRIFORM CLOUDS SHOULD THIN/SCATTER OUT BY LATER
THIS EVENING/OVERNIGHT.
KED
&&
.PREV DISCUSSION... /ISSUED 553 AM CST FRI JAN 11 2013/
AVIATION...12Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
IFR/MVFR CLOUDS ARE ON THE WANE AS A RESULT OF BOTH AN INCREASE IN
SOUTH WINDS AND THE INFLUX OF RELATIVELY DRIER AIR. HIGH LEVEL
MOISTURE FORECASTS SUGGEST CIRRUS WILL BE PERVASIVE THROUGHOUT THE
DAY...BUT SHOULD WANE SLIGHTLY THIS AFTERNOON. THE COLD FRONT WILL
SWEEP ACROSS ALL SITES AFTER DARK...WITH GUSTY NORTH NORTHWEST
WINDS IN ITS WAKE. MAY SQUEEZE OUT A FEW LOW CLOUDS JUST BEHIND
THE FRONT...BUT NO CEILINGS ARE ANTICIPATED AT THIS TIME.
-HOWERTON
PREV DISCUSSION... /ISSUED 317 AM CST FRI JAN 11 2013/
DISCUSSION...
FORECAST HIGHLIGHTS FOCUS AROUND MILD AND WINDY CONDITIONS
TODAY...COLDER TEMPERATURES SATURDAY-MONDAY...SOUTHEAST KS SNOW
CHANCES SATURDAY EVENING...AND MODERATING TEMPERATURES
TUESDAY-THURSDAY.
WILL GO AHEAD AND NIX THE CURRENT DENSE FOG ADVISORY ACROSS MUCH OF
THE AREA...AS SOMEWHAT WARMER/DRIER AIR IN CONCERT WITH
STRENGTHENING BOUNDARY LAYER WINDS HAS ENCROACHED FROM THE SOUTH.
A POWERFUL SHORTWAVE WILL ROUND THE BASE OF A WESTERN CONUS TROUGH
TODAY...RESULTING IN STRONG CYCLOGENESIS ACROSS THE HIGH PLAINS.
ASSOCIATED STRONG PRESSURE FALLS WILL RESULT IN STOUT/GUSTY
SOUTH/SOUTHWESTERLY WINDS ACROSS THE ENTIRE AREA...LIKELY STRONGEST
WEST OF I-135...WHERE A WIND ADVISORY IS IN EFFECT FROM 11AM-7PM.
CONTEMPLATED EXPANDING INTO EASTERN KS...BUT RELATIVELY MOIST
BOUNDARY LAYER AND SUBSEQUENT LESS DEEP MIXING HEIGHT SHOULD PREVENT
WIDESPREAD WIND ADVISORY CRITERIA THERE. THE DEEP/THICK ATMOSPHERE
AHEAD OF THE WESTERN CONUS LONGWAVE TROUGH IN TANDEM WITH THE STRONG
SOUTHERLY FLOW WILL ALLOW FOR WELL ABOVE NORMAL TEMPERATURES TODAY
ACROSS THE AREA...ALTHOUGH WE SHOULD FALL JUST SHORT OF RECORD HIGHS.
OTHERWISE...A 2ND PIECE OF SHORTWAVE ENERGY ROUNDS THE BASE OF THE
WESTERN CONUS TROUGH SATURDAY EVENING...INTERACTING WITH A STALLED
TIGHT/DEEP FRONTAL ZONE TO POSSIBLY BRING SOME WINTERY PRECIPITATION
TO FAR SOUTHEAST KS. THE LATEST NAM KEEPS THE BEST MID-LEVEL
FRONTOGENESIS TO THE SOUTHEAST OF THE FORECAST AREA...WHICH WOULD
RESULT IN LOWER PRECIPITATION CHANCES. HOWEVER...THE GFS AND
ESPECIALLY THE ECMWF CONTINUES TO KEEP THE BAROCLINIC ZONE A BIT
FURTHER NORTHWEST...WHICH WOULD RESULT IN HIGHER PRECIPITATION
CHANCES OVER FAR SOUTHEAST KS...WITH POTENTIALLY UP TO 1-2 INCHES OF
SNOW IN A NARROW SWATH. FALLING PRECIPITATION WILL HAVE TO OVERCOME
A VERY DRY SUB-700MB LAYER...BUT THINKING STRENGTH OF FRONTOGENESIS
AND NAM/GFS PROGGED MID-LEVEL INSTABILITY IS ENOUGH TO KEEP 40-50
POPS OVER FAR SOUTHEAST KS. IF THE NAM COMES AROUND TO THE GFS/ECMWF
SOLUTIONS...POPS WILL NEED TO BE INCREASED.
OTHERWISE...A MUCH COLDER AIRMASS WILL FILTER SOUTH ACROSS THE
REGION SATURDAY-MONDAY...AS THE WESTERN CONUS LONGWAVE TROUGH TRACKS
EAST...AND REINFORCING SHORTWAVES SHOOT SOUTHEAST OUT OF CANADA.
TEMPERATURES WILL FALL BACK TO BELOW NORMAL VALUES. HOWEVER...MODEL
CONSENSUS SUGGESTS WESTERN CONUS RIDGING BY EARLY-MID WEEK...WHICH
SHOULD RESULT IN MODERATING TEMPERATURES TUESDAY THROUGH WEEKS END.
THE ECMWF CONTINUES TO KICK A SOUTHERN STREAM SYSTEM EAST ACROSS THE
SOUTHERN PLAINS LATE WEEK...BUT IT HAS CONSISTENTLY REMAINED SOUTH
OF THE FORECAST AREA...SO WILL KEEP A DRY FORECAST IN BEYOND
TOMORROW NIGHT.
ADK
FIRE WEATHER...
WINDY AND RELATIVELY WARM CONDITIONS TODAY IN CONCERT WITH FALLING
RELATIVELY HUMIDITY VALUES WILL RESULT IN VERY HIGH GRASSLAND FIRE
DANGER ALL AREAS TODAY...WITH BORDER-LINE EXTREME FIRE DANGER
GENERALLY WEST OF I-135. THERE ARE SOME QUESTIONS ON MAGNITUDE OF
DRIER AIR PUNCHING IN FROM THE WEST THIS AFTERNOON WEST OF
I-135...ALONG WITH THE CURRENT MOIST GROUND FROM RECENT RAINS...SO
HELD OFF ON RED FLAG WARNING. NEVERTHELESS...OUTDOOR BURNING SHOULD
BE AVOIDED TODAY.
ADK
CLIMATE...
DESPITE COOLER AIR FILTERING SOUTHEAST ACROSS THE REGION
TONIGHT...RECORD WARM LOWS MAY BE IN JEOPARDY TODAY.
ADDITIONALLY...WITH FORECAST HIGH TEMPERATURES IN THE MID
60S...THINKING ALL SITES WILL FALL SHORT OF RECORDS WHICH ARE IN THE
UPPER 60S TO LOW 70S.
ADK
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 65 27 38 19 / 10 10 0 10
HUTCHINSON 64 24 35 16 / 10 0 0 10
NEWTON 64 26 36 17 / 10 10 0 10
ELDORADO 65 29 38 18 / 10 10 10 10
WINFIELD-KWLD 66 32 41 20 / 10 10 10 20
RUSSELL 60 18 29 12 / 10 0 0 10
GREAT BEND 60 20 32 13 / 10 0 0 10
SALINA 61 22 32 16 / 10 0 0 10
MCPHERSON 63 23 34 16 / 10 10 0 10
COFFEYVILLE 66 39 42 22 / 10 10 30 40
CHANUTE 65 36 41 20 / 10 10 20 40
IOLA 64 35 40 20 / 10 10 20 40
PARSONS-KPPF 65 38 42 20 / 10 10 20 40
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 7 PM CST THIS EVENING FOR KSZ032-033-047>051-
067-082-091.
RED FLAG WARNING UNTIL 6 PM CST THIS EVENING FOR KSZ032-047.
&&
$$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
959 PM EST SAT JAN 12 2013
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN ANCHORED OFF THE SOUTHEAST COAST THROUGH
SUNDAY. A COLD FRONT WILL PASS THROUGH THE REGION LATE SUNDAY
NIGHT INTO EARLY MONDAY. LOW PRESSURE MAY DEVELOP ON THE BOUNDARY
TO THE SOUTH...BRINGING UNSETTLED CONDITIONS TUESDAY. HIGH
PRESSURE IS EXPECTED TO RETURN TO THE MID ATLANTIC REGION
WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
UPDATE...
OPTED TO EXPAND DENSE FOG ADVISORY INTO THE CHARLOTTESVILLE AREA.
CHO OB NOT THERE YET...BUT GUIDANCE POINTS TO 1/4SM FORMING
OVERNIGHT AND THIS AREA IS ALREADY SURROUNDED BY SIMILARLY LOW
VSBYS. REST SAME.
PREV...
MAIN IMPACT OVERNIGHT WILL BE DENSE FOG. PLENTY OF LOW LEVEL
MOISTURE REMAINS...AND DENSE FOG AND STRATUS HAVE ALREADY FORMED
ACROSS PORTIONS OF NORTHERN VIRGINIA AND SOUTHERN MARYLAND. THE
EXPECTATION IS FOR THIS TO EXPAND FURTHER NORTHEAST THROUGH
CENTRAL MARYLAND THROUGH THE REST OF THE EVENING. DENSE FOG
ADVISORY WAS ISSUED EARLIER THIS EVENING FOR THIS.
THERE IS MORE UNCERTAINTY REGARDING THE SOUTH AND WEST EXTENT OF
THE DENSE FOG. IT LOOKS LIKE THERE IS AN OLD DIFFUSE BOUNDARY IN
PLACE THAT MAY HELP DICTATE THE SOUTH AND WEST EXTENT OF THE FOG.
ITS POSSIBLE THAT THE ADVISORY MAY NEED TO BE EXPANDED FURTHER
SOUTH INTO THE CHARLOTTESVILLE AREA AND PERHAPS ALSO INTO WESTERN
MARYLAND AND THE EASTERN WEST VIRGINIA PANHANDLE AT SOME POINT IF
THE RUC IS CORRECT. WILL CONTINUE TO MONITOR THROUGH THE EVENING.
THERE IS ALSO A WEAK WAVE THAT MAY BRING A FEW SHOWERS NOW THROUGH
MIDNIGHT OR SO ACROSS PORTIONS OF THE ALLEGHENY HIGHLANDS.
SCATTERED SHOWERS HAVE ALREADY BEEN ADDED TO THE GRIDS THROUGH
ABOUT THEN. ANY RAINFALL WOULD BE VERY LIGHT.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
SUNDAY - A REPEAT OF TODAY...BUT WARMER. WITH OVERNIGHT LOWS ONLY
DROPPING BARELY INTO THE 40S...WE`LL BE ON THE WAY TO 60S/70S EVEN
W/ YET ANOTHER SLOW START. WIDESPREAD FOG...DENSE IN SOME
AREAS...WILL AGAIN COVER MUCH OF THE REGION. A LIGHT WIND DURING
THE PREDAWN HRS OUT OF THE SE WILL LIKELY HELP TO KEEP CONDITIONS
A BIT MORE MIXED THAN THEY WERE THIS MORNING. ONCE THE FOG
DISSIPATES AND SKIES CLEAR OUT - CLOSER TO NOON/LIKE THIS MRNG -
TEMPS WILL BE WELL ON THEIR WAY TO THE 60S NORTH OF THE I-66
CORRIDOR AND POSSIBLY REACHING THE L70S OVER THE SRN HALF OF THE
CWA. MORE UPPER CIRRUS AND SOME PATCHY MID CLOUD DECKS WILL SPREAD
ACROSS THE AREA LATER IN THE DAY...CUTTING DOWN ON THE TEMPS A
COUPLE OF DEGREES BUT STILL A PLEASANT AFTN TO SPEND OUTDOORS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
WE ARE NOW IN WHAT IS CLIMATOLOGICALLY THE COLDEST WK OF THE
YR...AND THERE IS A NOTICEABLE ABSENCE OF COLD AIR IN THE ERN U.S.
IN THE WK AHD.
AS WAS WRITTEN ABV SUNDAY LOOKS TO BE A DAY W/ TEMPS BETTER SUITED
FOR APR THAN JAN...AND THE WELL-ABV-NRML TEMPS SHOULD CONT SUN NGT
W/ LOWS IN THE 50S E OF I-81. A COLD FRONT IS XPCTD TO CROSS THE
AREA LATE SUN NGT...HOWEVER AS THE FNT IS CAUGHT UP IN SW-NE FLOW
THE TEMPERATURE PUNCH AFTR FROPA WON`T BE VERY STRONG. THE FNT WL
SERVE AS FOCUS FOR RW MON...HIGHS WL AGN GET INTO THE 50S OVR THE
MAJORITY OF THE CWA. W/ FNT NOT MAKING A VERY FAST PUSH OFFSHORE
XPCT MON TO RMN M CLDY.
W OF THE CITIES...MDLS IMPLY THERE MAY BE ENUF COLDER AIR AVBL MON NGT/TUE
AS FNT MOVES E OF THE CWA FOR ANY MOISTURE THAT FALLS MAY AT LEAST
MIX W/ SNOW. GFS SHOWS SUB 130 DM THCKNS IN 850-000 LYR FM
FREDERICK MD TO FREDERICK VA...SO THE ATMOSPHERE IS MAKING A
FEEBLE ATTEMPT AT CREATING THE RIGHT CONDS FOR WINTRY PCPN. FOR
TIME BEING W/ KEEP THE WRN HALF OF THE CWA IN CHC R/S LATE MON NGT
AND TUE.
HIGH PRES PROGGED TO MOVE BACK INTO THE RGN BEHIND THE FNT WED. AN
ALBERTA CLIPPER LOOKING SYSTEM IS XPCTD TO TRAVERSE ALONG THE
US/CANADIAN BRDR WED NGT...BUT THE MAIN ENERGY W/ THIS IS XPCTD
TO TRACK WELL N OF THE CWA. WORST CASE SCENARIO FOR THE CWA WOULD
BE UPSLOPE SNSH IN THE HIGHLANDS LATE WED NGT/THU.
NEXT WKND IS A BIG ONE FOR DC. AT THIS TIME NO REAL COLD PUSHES
ARE FORESEEN.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
IAD/DCA HAVE ALREADY DROPPED BELOW MINIMUMS IN FOG/STRATUS THIS
EVENING. WITH LOW LEVEL MOISTURE REMAINING TRAPPED TONIGHT...SEE
NO REASON WHY ANY IMPROVEMENT WOULD OCCUR. IN FACT...EXPECTATION
IS FOR LIFR/VLIFR TO EXPAND TO INCLUDE BWI/MTN LATER THIS EVENING
OR OVERNIGHT. CHO/MRB ALSO EXPECTED TO FOLLOW SUIT ALTHOUGH
CONFIDENCE IS A LITTLE LOWER FOR MRB GIVEN DIFFERING GUIDANCE.
FLIGHT RESTRICTIONS WILL TAKE A WHILE TO IMPROVE ON SUNDAY...AND
IMPROVEMENT ABOVE IFR MAY NOT OCCUR UNTIL NOON OR AFTER.
MAV GUIDANCE SUGGESTS ANOTHER ROUND OF FOG/STRATUS SUNDAY
NIGHT...HOWEVER MET DOES NOT AND SREFS IS MORE ON THE CONSERVATIVE
SIDE TOO. BUT LOOKING AT FORECAST SOUNDINGS...UNTIL A COLD FRONT
MOVES THROUGH LOW LEVEL MOISTURE IS FORECAST TO REMAIN SO FAVOR
THE MAV SOLUTION WITH IMPROVEMENT OCCURRING WITH A FROPA/WIND
SHIFT EARLY MONDAY.
A COLD FRONT WILL PASS THROUGH THE TERMINALS EARLY MONDAY
MORNING WITH A CHANCE OF SHOWERS. SOUTH WINDS WILL SHIFT TO THE
NORTHWEST MON MRNG WITH GUSTS UP TO 15-20 KNOTS.
THE COLD FRONT WILL MOVE OFF TO THE SOUTHEAST MONDAY...BUT WAVES OF
LOW PRESSURE WILL BRING UNSETTLED CONDITIONS TUE. SUBVFR
CIGS/VSBYS ARE PSBL. HIGH PRESSURE WILL RETURN WED.
&&
.MARINE...
LOW VISIBILITY WILL BE THE ISSUE OVER THE WATERS TONIGHT INTO
SUNDAY MORNING...AS WIDESPREAD VSBYS BELOW 1 NM ARE EXPECTED.
GENERALLY LIGHT /LESS THAN 10 KT/ E/SE FLOW IS EXPECTED THROUGH
SUNDAY.
A COLD FRONT WILL PASS THROUGH THE WATERS MONDAY WITH SHOWERS
POSSIBLE. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR PORTIONS OF THE
WATERS MONDAY.
UNSETTLED CONDITIONS ARE EXPECTED MONDAY THROUGH TUESDAY WITH HIGH
PRESSURE RETURNING TO THE WATERS WEDNESDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...DENSE FOG ADVISORY UNTIL NOON EST SUNDAY FOR DCZ001.
MD...DENSE FOG ADVISORY UNTIL NOON EST SUNDAY FOR MDZ004>007-
009>011-013-014-016>018.
VA...DENSE FOG ADVISORY UNTIL NOON EST SUNDAY FOR VAZ036>040-042-
050>057-501-502.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BPP/GMS/ABW
NEAR TERM...BPP
SHORT TERM...GMS
LONG TERM...ABW
AVIATION...BPP/GMS/ABW
MARINE...BPP/GMS/ABW
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
936 PM EST SAT JAN 12 2013
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN ANCHORED OFF THE SOUTHEAST COAST THROUGH
SUNDAY. A COLD FRONT WILL PASS THROUGH THE REGION LATE SUNDAY
NIGHT INTO EARLY MONDAY. LOW PRESSURE MAY DEVELOP ON THE BOUNDARY
TO THE SOUTH...BRINGING UNSETTLED CONDITIONS TUESDAY. HIGH
PRESSURE IS EXPECTED TO RETURN TO THE MID ATLANTIC REGION
WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
MAIN IMPACT OVERNIGHT WILL BE DENSE FOG. PLENTY OF LOW LEVEL
MOISTURE REMAINS...AND DENSE FOG AND STRATUS HAVE ALREADY FORMED
ACROSS PORTIONS OF NORTHERN VIRGINIA AND SOUTHERN MARYLAND. THE
EXPECTATION IS FOR THIS TO EXPAND FURTHER NORTHEAST THROUGH
CENTRAL MARYLAND THROUGH THE REST OF THE EVENING. DENSE FOG
ADVISORY WAS ISSUED EARLIER THIS EVENING FOR THIS.
THERE IS MORE UNCERTAINTY REGARDING THE SOUTH AND WEST EXTENT OF
THE DENSE FOG. IT LOOKS LIKE THERE IS AN OLD DIFFUSE BOUNDARY IN
PLACE THAT MAY HELP DICTATE THE SOUTH AND WEST EXTENT OF THE FOG.
ITS POSSIBLE THAT THE ADVISORY MAY NEED TO BE EXPANDED FURTHER
SOUTH INTO THE CHARLOTTESVILLE AREA AND PERHAPS ALSO INTO WESTERN
MARYLAND AND THE EASTERN WEST VIRGINIA PANHANDLE AT SOME POINT IF
THE RUC IS CORRECT. WILL CONTINUE TO MONITOR THROUGH THE EVENING.
THERE IS ALSO A WEAK WAVE THAT MAY BRING A FEW SHOWERS NOW THROUGH
MIDNIGHT OR SO ACROSS PORTIONS OF THE ALLEGHENY HIGHLANDS.
SCATTERED SHOWERS HAVE ALREADY BEEN ADDED TO THE GRIDS THROUGH
ABOUT THEN. ANY RAINFALL WOULD BE VERY LIGHT.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
SUNDAY - A REPEAT OF TODAY...BUT WARMER. WITH OVERNIGHT LOWS ONLY
DROPPING BARELY INTO THE 40S...WE`LL BE ON THE WAY TO 60S/70S EVEN
W/ YET ANOTHER SLOW START. WIDESPREAD FOG...DENSE IN SOME
AREAS...WILL AGAIN COVER MUCH OF THE REGION. A LIGHT WIND DURING
THE PREDAWN HRS OUT OF THE SE WILL LIKELY HELP TO KEEP CONDITIONS
A BIT MORE MIXED THAN THEY WERE THIS MORNING. ONCE THE FOG
DISSIPATES AND SKIES CLEAR OUT - CLOSER TO NOON/LIKE THIS MRNG -
TEMPS WILL BE WELL ON THEIR WAY TO THE 60S NORTH OF THE I-66
CORRIDOR AND POSSIBLY REACHING THE L70S OVER THE SRN HALF OF THE
CWA. MORE UPPER CIRRUS AND SOME PATCHY MID CLOUD DECKS WILL SPREAD
ACROSS THE AREA LATER IN THE DAY...CUTTING DOWN ON THE TEMPS A
COUPLE OF DEGREES BUT STILL A PLEASANT AFTN TO SPEND OUTDOORS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
WE ARE NOW IN WHAT IS CLIMATOLOGICALLY THE COLDEST WK OF THE
YR...AND THERE IS A NOTICEABLE ABSENCE OF COLD AIR IN THE ERN U.S.
IN THE WK AHD.
AS WAS WRITTEN ABV SUNDAY LOOKS TO BE A DAY W/ TEMPS BETTER SUITED
FOR APR THAN JAN...AND THE WELL-ABV-NRML TEMPS SHOULD CONT SUN NGT
W/ LOWS IN THE 50S E OF I-81. A COLD FRONT IS XPCTD TO CROSS THE
AREA LATE SUN NGT...HOWEVER AS THE FNT IS CAUGHT UP IN SW-NE FLOW
THE TEMPERATURE PUNCH AFTR FROPA WON`T BE VERY STRONG. THE FNT WL
SERVE AS FOCUS FOR RW MON...HIGHS WL AGN GET INTO THE 50S OVR THE
MAJORITY OF THE CWA. W/ FNT NOT MAKING A VERY FAST PUSH OFFSHORE
XPCT MON TO RMN M CLDY.
W OF THE CITIES...MDLS IMPLY THERE MAY BE ENUF COLDER AIR AVBL MON NGT/TUE
AS FNT MOVES E OF THE CWA FOR ANY MOISTURE THAT FALLS MAY AT LEAST
MIX W/ SNOW. GFS SHOWS SUB 130 DM THCKNS IN 850-000 LYR FM
FREDERICK MD TO FREDERICK VA...SO THE ATMOSPHERE IS MAKING A
FEEBLE ATTEMPT AT CREATING THE RIGHT CONDS FOR WINTRY PCPN. FOR
TIME BEING W/ KEEP THE WRN HALF OF THE CWA IN CHC R/S LATE MON NGT
AND TUE.
HIGH PRES PROGGED TO MOVE BACK INTO THE RGN BEHIND THE FNT WED. AN
ALBERTA CLIPPER LOOKING SYSTEM IS XPCTD TO TRAVERSE ALONG THE
US/CANADIAN BRDR WED NGT...BUT THE MAIN ENERGY W/ THIS IS XPCTD
TO TRACK WELL N OF THE CWA. WORST CASE SCENARIO FOR THE CWA WOULD
BE UPSLOPE SNSH IN THE HIGHLANDS LATE WED NGT/THU.
NEXT WKND IS A BIG ONE FOR DC. AT THIS TIME NO REAL COLD PUSHES
ARE FORESEEN.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
IAD/DCA HAVE ALREADY DROPPED BELOW MINIMUMS IN FOG/STRATUS THIS
EVENING. WITH LOW LEVEL MOISTURE REMAINING TRAPPED TONIGHT...SEE
NO REASON WHY ANY IMPROVEMENT WOULD OCCUR. IN FACT...EXPECTATION
IS FOR LIFR/VLIFR TO EXPAND TO INCLUDE BWI/MTN LATER THIS EVENING
OR OVERNIGHT. CHO/MRB ALSO EXPECTED TO FOLLOW SUIT ALTHOUGH
CONFIDENCE IS A LITTLE LOWER FOR MRB GIVEN DIFFERING GUIDANCE.
FLIGHT RESTRICTIONS WILL TAKE A WHILE TO IMPROVE ON SUNDAY...AND
IMPROVEMENT ABOVE IFR MAY NOT OCCUR UNTIL NOON OR AFTER.
MAV GUIDANCE SUGGESTS ANOTHER ROUND OF FOG/STRATUS SUNDAY
NIGHT...HOWEVER MET DOES NOT AND SREFS IS MORE ON THE CONSERVATIVE
SIDE TOO. BUT LOOKING AT FORECAST SOUNDINGS...UNTIL A COLD FRONT
MOVES THROUGH LOW LEVEL MOISTURE IS FORECAST TO REMAIN SO FAVOR
THE MAV SOLUTION WITH IMPROVEMENT OCCURRING WITH A FROPA/WIND
SHIFT EARLY MONDAY.
A COLD FRONT WILL PASS THROUGH THE TERMINALS EARLY MONDAY
MORNING WITH A CHANCE OF SHOWERS. SOUTH WINDS WILL SHIFT TO THE
NORTHWEST MON MRNG WITH GUSTS UP TO 15-20 KNOTS.
THE COLD FRONT WILL MOVE OFF TO THE SOUTHEAST MONDAY...BUT WAVES OF
LOW PRESSURE WILL BRING UNSETTLED CONDITIONS TUE. SUBVFR
CIGS/VSBYS ARE PSBL. HIGH PRESSURE WILL RETURN WED.
&&
.MARINE...
LOW VISIBILITY WILL BE THE ISSUE OVER THE WATERS TONIGHT INTO
SUNDAY MORNING...AS WIDESPREAD VSBYS BELOW 1 NM ARE EXPECTED.
GENERALLY LIGHT /LESS THAN 10 KT/ E/SE FLOW IS EXPECTED THROUGH
SUNDAY.
A COLD FRONT WILL PASS THROUGH THE WATERS MONDAY WITH SHOWERS
POSSIBLE. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR PORTIONS OF THE
WATERS MONDAY.
UNSETTLED CONDITIONS ARE EXPECTED MONDAY THROUGH TUESDAY WITH HIGH
PRESSURE RETURNING TO THE WATERS WEDNESDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...DENSE FOG ADVISORY UNTIL NOON EST SUNDAY FOR DCZ001.
MD...DENSE FOG ADVISORY UNTIL NOON EST SUNDAY FOR MDZ004>007-
009>011-013-014-016>018.
VA...DENSE FOG ADVISORY UNTIL NOON EST SUNDAY FOR VAZ039-040-042-
050>057-501-502.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BPP/GMS/ABW
NEAR TERM...BPP
SHORT TERM...GMS
LONG TERM...ABW
AVIATION...BPP/GMS/ABW
MARINE...BPP/GMS/ABW
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
158 PM EST FRI JAN 11 2013
.UPDATE...
ISSUED AT 155 PM EST FRI JAN 11 2013
UPDATED THE FORECAST EARLIER TO INCLUDE DENSE FOG ADVISORY FOR S
CENTRAL AREAS...AND SPS FOR ALL BUT GOGEBIC AND ONTONAGON COUNTIES
FOR MUCH OF THE REST OF THE TODAY PERIOD. MNM AND ESC REPORTING
STATION HAD BEEN STUCK WITH 1/4SM VIS SINCE APPROX 12Z. SOME
SIGNIFICANT IMPROVEMENT/MIXING HAS BEEN NOTED AROUND AND S OF MNM
OVER THE PAST HOUR. WILL NEED TO CONTINUE TO MONITOR...WITH THE
POTENTIAL OF GETTING RID OF THE ADVISORY AT LEAST TEMPORARILY BY
LATE AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 545 AM EST FRI JAN 11 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
IDAHO INTO SRN CA AND AZ AND A RIDGE OVER THE ERN CONUS RESULTING IN
SW FLOW FROM THE CENTRAL PLAINS INTO THE NRN GREAT LAKES. ONE
SHORTWAVE TROUGH WAS LIFTING NE FROM CNTRL IL WHILE AN UPSTREAM
SHRTWV WAS MOVING FROM UTAH INTO COLORADO. AT THE SFC...SRLY FLOW
PREVAILED AHEAD OF A BROAD TROUGH EXTENDING FROM NE CO THROUGH CNTRL
SD INTO NW MN. THE BAND OF 295K-300K ISENTROPIC LIFT THAT SUPPORTED
THE BAND OF LIGHT RAIN HAD LIFTED TO THE NORTH AND EAST OF THE CWA
LEAVING A LARGE AREA OF LOW LEVEL MOISTURE AND WEAKER 285K-290K
ISENTROPIC ASCENT(BELOW 850 MB) WHICH SUPPORTED MAINLY PATCHY LIGHT
RAIN OR DRIZZLE. ALTHOUGH 2M TEMPS WERE ABOVE FREEZING ...IN THE 33F
TO 35F AT MOST REPORTING SITES...GROUND TEMPS IN MANY LOCATIONS WERE
STILL AT OR BELOW FREEZING. THE OVERNIGHT RAIN HAS RESULTED IN ICY
SECONDARY ROADS...ESPECIALLY OVER THE HIGHER TERRAIN IN CENTRAL
UPPER MICHIGAN.
TODAY...THE MORE SUBSTANTIAL PCPN ASSOCIATED WITH THE IL SHORTWAVE
WILL PASS WELL TO THE SOUTHEAST OF UPPER MI. HOWEVER...THE MOIST
SRLY FLOW AND CONTINUED WEAK LOW LEVEL ISENTROPIC ASCENT COULD
CONTINUE TO SUPPORT SOME PATCHY LIGHT RAIN AND MAINLY JUST DRIZZLE
BY THIS AFTERNOON. SINCE TEMPS WILL ONLY SLOWLY RISE THIS MORNING
...THE FREEZING RAIN ADVISORY WAS RETAINED THROUGH 12Z.
BY MID TO LATE MORNING...WITH TEMPS INTO THE MID AND UPPER 30S...ANY
LINGERING PROBLEMS WITH ICY ROADS SHOULD DIMINISH.
TONIGHT...MODELS WERE IN GOOD AGREEMENT WITH THE MAIN FEATURES
IMPACTING THE UPPER GREAT LAKES. AS THE CO SHORTWAVE TROUGH LIFTS TO
THE NORTHEAST...A SFC LO IS EXPECTED TO MOVE FROM THE PLAINS TO NE
MN BY 12Z SAT. MODELS INDICATE THAT THE DRY SLOT UNDER THE JET SURGE
WILL DOMINATE...LIMITING PCPN CHANCES TO MAINLY DRIZZLE OR PATCHY
LIGHT RAIN. WITH A STEADY S WIND AND LINGERING LOW CLOUDS...EXPECT
STEADY OR SLOWLY RISING TEMPS THROUGH MUCH OF THE NIGHT AS THE COLD
FRONT ONLY APPROACHES THE FAR WEST BY AROUND 12Z. EXPECT AREAS OF
FOG AWAY FROM THE DOWNSLOPE AREAS NEAR LAKE SUPERIOR WITH MOIST LOW
LEVELS AND MELTING SNOW.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 545 AM EST FRI JAN 11 2013
TROF CONTINUES TO AMPLIFY OVER THE WRN CONUS AS PATTERN CHANGE IS
UNDERWAY. TROF WILL SLOWLY PROGRESS E OVER THE NEXT WEEK...THOUGH
WITH UNCERTAIN AMPLITUDE. MEDIUM RANGE GUIDANCE CONTINUES TO SHOW A
STRENGTHENING POLAR VORTEX WITH A GREATLY EXPANDING AND INTENSIFYING
ARCTIC AIR MASS AROUND HUDSON BAY NEXT WEEK. WITH BUILDING HEIGHTS
FORECASTED OVER GREENLAND...THERE SHOULD BE A TENDENCY FOR THE
BITTER COLD AIR TO SLIP INTO THE UPPER LAKES. HOWEVER...WITH PHASE
OF RECENTLY STRENGTHENED MJO FAVORING WARMTH OVER THE ERN CONUS...IT
WILL BE INTERESTING TO SEE HOW FAR S THE REALLY BITTER COLD AIR
SINKS NEXT WEEK IN RESPONSE TO THE DEVELOPING BLOCKING HIGH OVER
GREENLAND. AT LEAST FOR NOW...WOULD STILL BE SKEPTICAL OF ANY MODEL
SOLUTIONS SHOWING 850MB TEMPS NEARING -30C OVER UPPER MI OR SHOWING
ANYTHING MORE THAN A BRIEF INTRUSION OF BITTER COLD AIR GIVEN
COMPETING SIGNALS FOR WARMTH/COLD. SO...FCST WILL CONTINUE TO SHOW A
CONSERVATIVE APPROACH TO THE COLD WITH TEMPS GENERALLY CLOSE TO OR A
LITTLE BLO NORMAL NEXT WEEK. WITH SNOW COVER GETTING THIN IN MANY
AREAS AND NOT LIKELY TO INCREASE MUCH IF AT ALL AWAY FROM THE W AND
WNW WIND LES SNOW BELTS...THERE COULD BE PROBLEMS FOR WATER LINES IF
WE DO SEE ANYTHING MORE THAN JUST A SHORT DURATION OF SEVERE COLD.
AS JUST ALLUDED TO...PATTERN WILL BE A DRY ONE WITH LITTLE CHC FOR
ANY WIDESPREAD SYNOPTIC SNOW...BUT LES WILL BE A PERSISTENT FEATURE
OF THE FCST NEXT WEEK. IT APPEARS WESTERLY WINDS WILL PROBABLY
DOMINATE...PREVENTING MORE WIDESPREAD COVERAGE OF LES IN UPPER MI
MOST DAYS. THE KEWEENAW PENINSULA WILL SEE THE MOST SNOW FROM LES
NEXT WEEK...AND THERE MAY BE FAIRLY SUBSTANTIAL TOTALS FOR THE WEEK
THERE.
BEGINNING SAT...SHORTWAVE/SFC LOW WILL BE IN NE MN AT 12Z. AS SYSTEM
MOVES ENE THRU NRN ONTARIO DURING THE DAY...SHARP COLD FRONT WILL
CROSS UPPER MI. HOWEVER...SINCE STRONGEST DEEP LAYER QVECTOR
CONVERGENCE ACCOMPANYING DISTURBANCE PASSES TO THE N...AXIS OF MID
LEVEL DRY AIR IS FCST TO LINGER AND WILL LIKELY LEAD TO A DRY FROPA.
ONLY EXCEPTION MAY BE OVER THE W...CLOSER TO THE PASSING
DYNAMICS/DEEPER MOISTURE AND WHERE THE LOW-LEVEL FLOW WILL TAKE ON
MORE OF A CYCLONIC UPSLOPE COMPONENT...ESPECIALLY IN THE AFTN. 850MB
TEMPS FALLING TO AROUND -15C TOWARD 00Z SUN WILL ALSO ADD AN
INCREASING LES COMPONENT TO THE MIX. WITH WSW LOW-LEVEL WINDS...BEST
CHC FOR INCREASING -SHSN WILL BE OVER THE KEWEENAW. SHARP CAA (MAX
850MB TEMP FALL IS AROUND 10C IN 6HR) AND ISALLOBARIC WIND ALIGNED
WITH GRADIENT WIND (6MB/3HR PRES RISE FOLLOWING FROPA) WILL LEAD TO
WINDY CONDITIONS AFTER FROPA. SW WIND DIRECTION IS NOT TYPICALLY THE
MOST FAVORABLE DIRECTION FOR HIGH WINDS IN MOST LOCATIONS...BUT WITH
850MB WINDS AROUND 45KT...SOME GUSTS COULD APPROACH WIND ADVY
CRITERIA...MAINLY IN THE 1-3HRS DURING THE ISALLOBARIC WIND PUSH.
MOMENTUM TRANSFER SUGGESTS GUSTS OF 30-40MPH SHOULD GENERALLY BE THE
RULE FOR A FEW HRS AFTER FROPA. IN COMBINATION WITH FALLING SFC
TEMPS W TO E THRU THE DAY...THE AIR WILL BEGIN TO FEEL MUCH
COLDER...ESPECIALLY OVER THE W WHERE TEMP FALL WILL BE MOST
SIGNIFICANT.
SAT NIGHT THRU SUN NIGHT...AS COLDER AIR SETTLES INTO THE UPPER
GREAT LAKES...850MB TEMPS FALL INTO THE -16 TO -19C RANGE. LOOKS
LIKE A POTENTIALLY INTERESTING PERIOD OF LES AS GFS/NAM SHOW
MOISTURE PROFILE DEEPENING TO 10KFT OR MORE. WITH DEEP MOISTURE...
DENDRITIC SNOW GROWTH TEMPS FALLING FIRMLY INTO THE CONVECTIVE
LAYER...AND SFC TROF DRIFTING THRU THE AREA...THERE IS AN INCREASING
SIGNAL FOR MDT/HVY LES. SHOULD BE ABLE TO FLUFF UP SOME RATHER
SIGNIFICANT SNOW ACCUMULATIONS AS SNOW TO WATER RATIOS INCREASE TO
20-30 TO 1. THERE IS SOME UNCERTAINTY IN WIND DIRECTION WHICH WON`T
BE HANDLED WELL UNTIL CLOSER TO THE EVENT. OVERALL...MODELS INDICATE
A W TO WSW WIND SAT EVENING AHEAD OF TROF TO SHIFT WNW/NW SUN
MORNING AS SFC TROF PASSES. WITH SFC TROF APPROACHING...WOULD
EXPECT SAT NIGHT WINDS TO HAVE MORE OF A WSW/SW COMPONENT...
ESPECIALLY CONSIDERING LAND BREEZE COMPONENT WHICH SHOULD BE ACTIVE
AS LOW-LEVEL GRADIENT WINDS DIMINISH. THIS COULD LEAD TO A STRONG
CONVERGENCE ZONE/HVY LES SETTING UP FROM AROUND THE APOSTLE ISLANDS
INTO THE KEWEENAW SAT NIGHT. THE MDT/HVY SNOW WOULD THEN EXPAND TO
INCLUDE WNW/NW FAVORED SNOW BELTS FOR A TIME SUN. AT THIS POINT...
THE KEWEENAW PENINSULA APPEARS MOST LIKELY TO BE IMPACTED LONGEST BY
MDT/HVY LES. CONSIDERED A WATCH FOR KEWEENAW/NRN HOUGHTON COUNTIES
BEGINNING SAT NIGHT...BUT WILL LET NEXT SHIFT TAKE ANOTHER LOOK AS
WINDS MAY END UP MORE BACKED SAT NIGHT THAN CURRENTLY EXPECTED AHEAD
OF SFC TROF OR SFC TROF MAY PASS MORE QUICKLY THAN EXPECTED.
MON-THU...MOSTLY WEST WIND LES WILL CONTINUE. WHERE WINDS ARE
EXPECTED TO BE ONSHORE...OPTED FOR LIKELY/CATEGORICAL POPS DURING
THIS PERIOD. TUE IS ONLY DAY THAT MAY END UP DRY ACROSS UPPER MI AS
WINDS MAY BACK SUFFICIENTLY TO SHIFT LES OFFSHORE. OTHERWISE...
MEDIUM RANGE MODELS CONTINUE TO SHOW SIGNIFICANT
TIMING/TRACK/AMPLITUDE DIFFERENCES ON SHORTWAVES DROPPING SE INTO
THE GREAT LAKES NEXT WEEK TO THE S OF THE INTENSIFYING POLAR VORTEX
AROUND HUDSON BAY. ALSO...RUN-TO-RUN CONTINUITY WITH THE SHORTWAVES
REMAINS VERY POOR. SO...THERE`S NOT A LOT OF CONFIDENCE ON THE
SHORTWAVES AFFECTING THE AREA. IF ONE OF THE WAVES CAN AMPLIFY
SUFFICIENTLY...THEN BITTER COLD AIR WOULD PLUNGE INTO THE AREA.
WHETHER THAT HAPPENS REMAINS TO SEEN.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 155 PM EST FRI JAN 11 2013
LIFR TO IFR CEILINGS ACCOMPANIED BY VLIFR TO VFR VIS HAVE BEEN
COMMON...STREAMING IN ON VERY MOIST S FLOW. ALTHOUGH THERE HAVE
BEEN POCKETS OF VFR VIS...MOST NOTABLY AT IWD THANKS TO THE
DOWNSLOPE WIND DIRECTION. CMX IS RIGHT ON THE EDGE...AND WILL
CONTINUE TO BOUNCE AROUND...BUT WITH CEILINGS LIKELY KEEPING THE
SITE IN THE IFR TO LOW MVFR RANGE. WINDS WILL BE THE MAIN CHANGE
OVER THE NEXT 24 HOURS...INCREASING AND BECOMING GUSTY WITH GUSTS
NEARING 25KTS AT IWD AND CMX AROUND DAYBREAK.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 545 AM EST FRI JAN 11 2013
A TIGHT PRESSURE GRADIENT BETWEEN AN APPROACHING LOW PRESSURE TROUGH
FROM THE NRN PLAINS AND A RIDGE OVER THE EASTERN GREAT LAKES WILL
RESULT IN SOUTH TO SOUTHEAST WINDS TO 25 KNOTS ACROSS THE ERN HALF
OF LAKE SUPERIOR THIS MORNING. WINDS SHOULD STAY AT OR BELOW 20 KTS
OVER THE WEST HALF. WINDS WILL DIMINISH BLO 20 KT FRI AFTERNOON AS
PRES GRADIENT WEAKENS.
WITH A WEAK PRES GRADIENT OVER THE LAKE THIS EVENING...EXPECT SSW WINDS
UNDER 20 KTS WINDS. BUT THE WINDS WILL INCREASE OVERNIGHT AS A DEEP
LOW PRESSURE SYSTEM MOVES NE FROM THE PLAINS INTO NE MN AND TIGHTENS
THE GRADIENT. EXPECT THE WINDS TO INCREASE RAPIDLY ON SAT AS A SHARP
COLD FRONT SLICES ACROSS THE UPPER GREAT LAKES AND THE ARRIVAL OF
MUCH COLDER AIR RESULTS IN DECREASING STABILITY AND GREATER MIXING OF
THE STRONGER WINDS TO THE LAKE SURFACE. A GALE WATCH WAS EXPANDED AS
GALES ARE EXPECTED ACROSS THE LAKE FROM SATURDAY MORNING INTO
SATURDAY EVENING. NOT OUT OF THE QUESTION THAT A FEW STORM FORCE
GUSTS COULD OCCUR OVER THE WRN LAKE AS WELL. THE COMBINATION OF THE
STRONG WINDS...COLDER AIR AND HIGHER WAVES WILL RESULT IN FREEZING
SPRAY AS WELL INTO SAT NIGHT WHEN THE WINDS WILL BE DIMINISHING WITH
THE DEPARTURE OF LOW PRES TO THE NORTHEAST. WINDS IN THE 15 TO 25 KT
RANGE ARE EXPECTED SUNDAY INTO MONDAY...BUT THE APPROACH OF ANOTHER
DISTURBANCE LATER ON TUE TUE AND NIGHT MIGHT RESULT IN W-SW WINDS
INCREASING TO GALES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
DENSE FOG ADVISORY UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
MIZ011>013.
LAKE SUPERIOR...
GALE WARNING FROM 10 AM EST /9 AM CST/ TO 10 PM EST /9 PM CST/
SATURDAY FOR LSZ240>246-265>267.
GALE WARNING FROM 7 AM EST /6 AM CST/ TO 10 PM EST /9 PM CST/
SATURDAY FOR LSZ162-263-264.
LAKE MICHIGAN...
DENSE FOG ADVISORY UNTIL 7 AM EST SATURDAY FOR LMZ221-248-250.
GALE WARNING FROM 11 AM TO 9 PM EST SATURDAY FOR LMZ221-248-250.
&&
$$
UPDATE...KF
SHORT TERM...JLB
LONG TERM...ROLFSON
AVIATION...KF
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
629 AM EST FRI JAN 11 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 545 AM EST FRI JAN 11 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
IDAHO INTO SRN CA AND AZ AND A RIDGE OVER THE ERN CONUS RESULTING IN
SW FLOW FROM THE CENTRAL PLAINS INTO THE NRN GREAT LAKES. ONE
SHORTWAVE TROUGH WAS LIFTING NE FROM CNTRL IL WHILE AN UPSTREAM
SHRTWV WAS MOVING FROM UTAH INTO COLORADO. AT THE SFC...SRLY FLOW
PREVAILED AHEAD OF A BROAD TROUGH EXTENDING FROM NE CO THROUGH CNTRL
SD INTO NW MN. THE BAND OF 295K-300K ISENTROPIC LIFT THAT SUPPORTED
THE BAND OF LIGHT RAIN HAD LIFTED TO THE NORTH AND EAST OF THE CWA
LEAVING A LARGE AREA OF LOW LEVEL MOISTURE AND WEAKER 285K-290K
ISENTROPIC ASCENT(BELOW 850 MB) WHICH SUPPORTED MAINLY PATCHY LIGHT
RAIN OR DRIZZLE. ALTHOUGH 2M TEMPS WERE ABOVE FREEZING ...IN THE 33F
TO 35F AT MOST REPORTING SITES...GROUND TEMPS IN MANY LOCATIONS WERE
STILL AT OR BELOW FREEZING. THE OVERNIGHT RAIN HAS RESULTED IN ICY
SECONDARY ROADS...ESPECIALLY OVER THE HIGHER TERRAIN IN CENTRAL
UPPER MICHIGAN.
TODAY...THE MORE SUBSTANTIAL PCPN ASSOCIATED WITH THE IL SHORTWAVE
WILL PASS WELL TO THE SOUTHEAST OF UPPER MI. HOWEVER...THE MOIST
SRLY FLOW AND CONTINUED WEAK LOW LEVEL ISENTROPIC ASCENT COULD
CONTINUE TO SUPPORT SOME PATCHY LIGHT RAIN AND MAINLY JUST DRIZZLE
BY THIS AFTERNOON. SINCE TEMPS WILL ONLY SLOWLY RISE THIS MORNING
...THE FREEZING RAIN ADVISORY WAS RETAINED THROUGH 12Z.
BY MID TO LATE MORNING...WITH TEMPS INTO THE MID AND UPPER 30S...ANY
LINGERING PROBLEMS WITH ICY ROADS SHOULD DIMINISH.
TONIGHT...MODELS WERE IN GOOD AGREEMENT WITH THE MAIN FEATURES
IMPACTING THE UPPER GREAT LAKES. AS THE CO SHORTWAVE TROUGH LIFTS TO
THE NORTHEAST...A SFC LO IS EXPECTED TO MOVE FROM THE PLAINS TO NE
MN BY 12Z SAT. MODELS INDICATE THAT THE DRY SLOT UNDER THE JET SURGE
WILL DOMINATE...LIMITING PCPN CHANCES TO MAINLY DRIZZLE OR PATCHY
LIGHT RAIN. WITH A STEADY S WIND AND LINGERING LOW CLOUDS...EXPECT
STEADY OR SLOWLY RISING TEMPS THROUGH MUCH OF THE NIGHT AS THE COLD
FRONT ONLY APPROACHES THE FAR WEST BY AROUND 12Z. EXPECT AREAS OF
FOG AWAY FROM THE DOWNSLOPE AREAS NEAR LAKE SUPERIOR WITH MOIST LOW
LEVELS AND MELTING SNOW.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 545 AM EST FRI JAN 11 2013
TROF CONTINUES TO AMPLIFY OVER THE WRN CONUS AS PATTERN CHANGE IS
UNDERWAY. TROF WILL SLOWLY PROGRESS E OVER THE NEXT WEEK...THOUGH
WITH UNCERTAIN AMPLITUDE. MEDIUM RANGE GUIDANCE CONTINUES TO SHOW A
STRENGTHENING POLAR VORTEX WITH A GREATLY EXPANDING AND INTENSIFYING
ARCTIC AIR MASS AROUND HUDSON BAY NEXT WEEK. WITH BUILDING HEIGHTS
FORECASTED OVER GREENLAND...THERE SHOULD BE A TENDENCY FOR THE
BITTER COLD AIR TO SLIP INTO THE UPPER LAKES. HOWEVER...WITH PHASE
OF RECENTLY STRENGTHENED MJO FAVORING WARMTH OVER THE ERN CONUS...IT
WILL BE INTERESTING TO SEE HOW FAR S THE REALLY BITTER COLD AIR
SINKS NEXT WEEK IN RESPONSE TO THE DEVELOPING BLOCKING HIGH OVER
GREENLAND. AT LEAST FOR NOW...WOULD STILL BE SKEPTICAL OF ANY MODEL
SOLUTIONS SHOWING 850MB TEMPS NEARING -30C OVER UPPER MI OR SHOWING
ANYTHING MORE THAN A BRIEF INTRUSION OF BITTER COLD AIR GIVEN
COMPETING SIGNALS FOR WARMTH/COLD. SO...FCST WILL CONTINUE TO SHOW A
CONSERVATIVE APPROACH TO THE COLD WITH TEMPS GENERALLY CLOSE TO OR A
LITTLE BLO NORMAL NEXT WEEK. WITH SNOW COVER GETTING THIN IN MANY
AREAS AND NOT LIKELY TO INCREASE MUCH IF AT ALL AWAY FROM THE W AND
WNW WIND LES SNOW BELTS...THERE COULD BE PROBLEMS FOR WATER LINES IF
WE DO SEE ANYTHING MORE THAN JUST A SHORT DURATION OF SEVERE COLD.
AS JUST ALLUDED TO...PATTERN WILL BE A DRY ONE WITH LITTLE CHC FOR
ANY WIDESPREAD SYNOPTIC SNOW...BUT LES WILL BE A PERSISTENT FEATURE
OF THE FCST NEXT WEEK. IT APPEARS WESTERLY WINDS WILL PROBABLY
DOMINATE...PREVENTING MORE WIDESPREAD COVERAGE OF LES IN UPPER MI
MOST DAYS. THE KEWEENAW PENINSULA WILL SEE THE MOST SNOW FROM LES
NEXT WEEK...AND THERE MAY BE FAIRLY SUBSTANTIAL TOTALS FOR THE WEEK
THERE.
BEGINNING SAT...SHORTWAVE/SFC LOW WILL BE IN NE MN AT 12Z. AS SYSTEM
MOVES ENE THRU NRN ONTARIO DURING THE DAY...SHARP COLD FRONT WILL
CROSS UPPER MI. HOWEVER...SINCE STRONGEST DEEP LAYER QVECTOR
CONVERGENCE ACCOMPANYING DISTURBANCE PASSES TO THE N...AXIS OF MID
LEVEL DRY AIR IS FCST TO LINGER AND WILL LIKELY LEAD TO A DRY FROPA.
ONLY EXCEPTION MAY BE OVER THE W...CLOSER TO THE PASSING
DYNAMICS/DEEPER MOISTURE AND WHERE THE LOW-LEVEL FLOW WILL TAKE ON
MORE OF A CYCLONIC UPSLOPE COMPONENT...ESPECIALLY IN THE AFTN. 850MB
TEMPS FALLING TO AROUND -15C TOWARD 00Z SUN WILL ALSO ADD AN
INCREASING LES COMPONENT TO THE MIX. WITH WSW LOW-LEVEL WINDS...BEST
CHC FOR INCREASING -SHSN WILL BE OVER THE KEWEENAW. SHARP CAA (MAX
850MB TEMP FALL IS AROUND 10C IN 6HR) AND ISALLOBARIC WIND ALIGNED
WITH GRADIENT WIND (6MB/3HR PRES RISE FOLLOWING FROPA) WILL LEAD TO
WINDY CONDITIONS AFTER FROPA. SW WIND DIRECTION IS NOT TYPICALLY THE
MOST FAVORABLE DIRECTION FOR HIGH WINDS IN MOST LOCATIONS...BUT WITH
850MB WINDS AROUND 45KT...SOME GUSTS COULD APPROACH WIND ADVY
CRITERIA...MAINLY IN THE 1-3HRS DURING THE ISALLOBARIC WIND PUSH.
MOMENTUM TRANSFER SUGGESTS GUSTS OF 30-40MPH SHOULD GENERALLY BE THE
RULE FOR A FEW HRS AFTER FROPA. IN COMBINATION WITH FALLING SFC
TEMPS W TO E THRU THE DAY...THE AIR WILL BEGIN TO FEEL MUCH
COLDER...ESPECIALLY OVER THE W WHERE TEMP FALL WILL BE MOST
SIGNIFICANT.
SAT NIGHT THRU SUN NIGHT...AS COLDER AIR SETTLES INTO THE UPPER
GREAT LAKES...850MB TEMPS FALL INTO THE -16 TO -19C RANGE. LOOKS
LIKE A POTENTIALLY INTERESTING PERIOD OF LES AS GFS/NAM SHOW
MOISTURE PROFILE DEEPENING TO 10KFT OR MORE. WITH DEEP MOISTURE...
DENDRITIC SNOW GROWTH TEMPS FALLING FIRMLY INTO THE CONVECTIVE
LAYER...AND SFC TROF DRIFTING THRU THE AREA...THERE IS AN INCREASING
SIGNAL FOR MDT/HVY LES. SHOULD BE ABLE TO FLUFF UP SOME RATHER
SIGNIFICANT SNOW ACCUMULATIONS AS SNOW TO WATER RATIOS INCREASE TO
20-30 TO 1. THERE IS SOME UNCERTAINTY IN WIND DIRECTION WHICH WON`T
BE HANDLED WELL UNTIL CLOSER TO THE EVENT. OVERALL...MODELS INDICATE
A W TO WSW WIND SAT EVENING AHEAD OF TROF TO SHIFT WNW/NW SUN
MORNING AS SFC TROF PASSES. WITH SFC TROF APPROACHING...WOULD
EXPECT SAT NIGHT WINDS TO HAVE MORE OF A WSW/SW COMPONENT...
ESPECIALLY CONSIDERING LAND BREEZE COMPONENT WHICH SHOULD BE ACTIVE
AS LOW-LEVEL GRADIENT WINDS DIMINISH. THIS COULD LEAD TO A STRONG
CONVERGENCE ZONE/HVY LES SETTING UP FROM AROUND THE APOSTLE ISLANDS
INTO THE KEWEENAW SAT NIGHT. THE MDT/HVY SNOW WOULD THEN EXPAND TO
INCLUDE WNW/NW FAVORED SNOW BELTS FOR A TIME SUN. AT THIS POINT...
THE KEWEENAW PENINSULA APPEARS MOST LIKELY TO BE IMPACTED LONGEST BY
MDT/HVY LES. CONSIDERED A WATCH FOR KEWEENAW/NRN HOUGHTON COUNTIES
BEGINNING SAT NIGHT...BUT WILL LET NEXT SHIFT TAKE ANOTHER LOOK AS
WINDS MAY END UP MORE BACKED SAT NIGHT THAN CURRENTLY EXPECTED AHEAD
OF SFC TROF OR SFC TROF MAY PASS MORE QUICKLY THAN EXPECTED.
MON-THU...MOSTLY WEST WIND LES WILL CONTINUE. WHERE WINDS ARE
EXPECTED TO BE ONSHORE...OPTED FOR LIKELY/CATEGORICAL POPS DURING
THIS PERIOD. TUE IS ONLY DAY THAT MAY END UP DRY ACROSS UPPER MI AS
WINDS MAY BACK SUFFICIENTLY TO SHIFT LES OFFSHORE. OTHERWISE...
MEDIUM RANGE MODELS CONTINUE TO SHOW SIGNIFICANT
TIMING/TRACK/AMPLITUDE DIFFERENCES ON SHORTWAVES DROPPING SE INTO
THE GREAT LAKES NEXT WEEK TO THE S OF THE INTENSIFYING POLAR VORTEX
AROUND HUDSON BAY. ALSO...RUN-TO-RUN CONTINUITY WITH THE SHORTWAVES
REMAINS VERY POOR. SO...THERE`S NOT A LOT OF CONFIDENCE ON THE
SHORTWAVES AFFECTING THE AREA. IF ONE OF THE WAVES CAN AMPLIFY
SUFFICIENTLY...THEN BITTER COLD AIR WOULD PLUNGE INTO THE AREA.
WHETHER THAT HAPPENS REMAINS TO SEEN.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 628 AM EST FRI JAN 11 2013
ABUNDANT LOW LEVEL MOISTURE WITH SRLY FLOW IS EXPECTED OVER THE
REGION THROUGH THE FORECAST PERIOD. SO...IFR CONDITIONS WILL PERSIST.
THERE MAY BE SOME SLIGHT IMPROVEMENT TO THE CEILINGS THIS
AFTERNOON...BEFORE THE FOG THAT AFFECTS THE SITES TONIGHT MOVES BACK
IN. KSAW SHOULD SEE THE LOWEST CEILINGS/VISIBILITY SINCE THEY WILL
BE MORE SUSCEPTIBLE TO SOUTHERLY UPSLOPE FLOW.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 545 AM EST FRI JAN 11 2013
A TIGHT PRESSURE GRADIENT BETWEEN AN APPROACHING LOW PRESSURE TROUGH
FROM THE NRN PLAINS AND A RIDGE OVER THE EASTERN GREAT LAKES WILL
RESULT IN SOUTH TO SOUTHEAST WINDS TO 25 KNOTS ACROSS THE ERN HALF
OF LAKE SUPERIOR THIS MORNING. WINDS SHOULD STAY AT OR BELOW 20 KTS
OVER THE WEST HALF. WINDS WILL DIMINISH BLO 20 KT FRI AFTERNOON AS
PRES GRADIENT WEAKENS.
WITH A WEAK PRES GRADIENT OVER THE LAKE THIS EVENING...EXPECT SSW WINDS
UNDER 20 KTS WINDS. BUT THE WINDS WILL INCREASE OVERNIGHT AS A DEEP
LOW PRESSURE SYSTEM MOVES NE FROM THE PLAINS INTO NE MN AND TIGHTENS
THE GRADIENT. EXPECT THE WINDS TO INCREASE RAPIDLY ON SAT AS A SHARP
COLD FRONT SLICES ACROSS THE UPPER GREAT LAKES AND THE ARRIVAL OF
MUCH COLDER AIR RESULTS IN DECREASING STABILITY AND GREATER MIXING OF
THE STRONGER WINDS TO THE LAKE SURFACE. A GALE WATCH WAS EXPANDED AS
GALES ARE EXPECTED ACROSS THE LAKE FROM SATURDAY MORNING INTO
SATURDAY EVENING. NOT OUT OF THE QUESTION THAT A FEW STORM FORCE
GUSTS COULD OCCUR OVER THE WRN LAKE AS WELL. THE COMBINATION OF THE
STRONG WINDS...COLDER AIR AND HIGHER WAVES WILL RESULT IN FREEZING
SPRAY AS WELL INTO SAT NIGHT WHEN THE WINDS WILL BE DIMINISHING WITH
THE DEPARTURE OF LOW PRES TO THE NORTHEAST. WINDS IN THE 15 TO 25 KT
RANGE ARE EXPECTED SUNDAY INTO MONDAY...BUT THE APPROACH OF ANOTHER
DISTURBANCE LATER ON TUE TUE AND NIGHT MIGHT RESULT IN W-SW WINDS
INCREASING TO GALES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
FREEZING RAIN ADVISORY UNTIL 7 AM EST /6 AM CST/ THIS MORNING
FOR MIZ001>007-009>011-084-085.
LAKE SUPERIOR...
GALE WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR
LSZ240>246-265>267.
GALE WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR
LSZ162-263-264.
LAKE MICHIGAN...
GALE WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR
LMZ221-248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...ROLFSON
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
557 AM EST FRI JAN 11 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 545 AM EST FRI JAN 11 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
IDAHO INTO SRN CA AND AZ AND A RIDGE OVER THE ERN CONUS RESULTING IN
SW FLOW FROM THE CENTRAL PLAINS INTO THE NRN GREAT LAKES. ONE
SHORTWAVE TROUGH WAS LIFTING NE FROM CNTRL IL WHILE AN UPSTREAM
SHRTWV WAS MOVING FROM UTAH INTO COLORADO. AT THE SFC...SRLY FLOW
PREVAILED AHEAD OF A BROAD TROUGH EXTENDING FROM NE CO THROUGH CNTRL
SD INTO NW MN. THE BAND OF 295K-300K ISENTROPIC LIFT THAT SUPPORTED
THE BAND OF LIGHT RAIN HAD LIFTED TO THE NORTH AND EAST OF THE CWA
LEAVING A LARGE AREA OF LOW LEVEL MOISTURE AND WEAKER 285K-290K
ISENTROPIC ASCENT(BELOW 850 MB) WHICH SUPPORTED MAINLY PATCHY LIGHT
RAIN OR DRIZZLE. ALTHOUGH 2M TEMPS WERE ABOVE FREEZING ...IN THE 33F
TO 35F AT MOST REPORTING SITES...GROUND TEMPS IN MANY LOCATIONS WERE
STILL AT OR BELOW FREEZING. THE OVERNIGHT RAIN HAS RESULTED IN ICY
SECONDARY ROADS...ESPECIALLY OVER THE HIGHER TERRAIN IN CENTRAL
UPPER MICHIGAN.
TODAY...THE MORE SUBSTANTIAL PCPN ASSOCIATED WITH THE IL SHORTWAVE
WILL PASS WELL TO THE SOUTHEAST OF UPPER MI. HOWEVER...THE MOIST
SRLY FLOW AND CONTINUED WEAK LOW LEVEL ISENTROPIC ASCENT COULD
CONTINUE TO SUPPORT SOME PATCHY LIGHT RAIN AND MAINLY JUST DRIZZLE
BY THIS AFTERNOON. SINCE TEMPS WILL ONLY SLOWLY RISE THIS MORNING
...THE FREEZING RAIN ADVISORY WAS RETAINED THROUGH 12Z.
BY MID TO LATE MORNING...WITH TEMPS INTO THE MID AND UPPER 30S...ANY
LINGERING PROBLEMS WITH ICY ROADS SHOULD DIMINISH.
TONIGHT...MODELS WERE IN GOOD AGREEMENT WITH THE MAIN FEATURES
IMPACTING THE UPPER GREAT LAKES. AS THE CO SHORTWAVE TROUGH LIFTS TO
THE NORTHEAST...A SFC LO IS EXPECTED TO MOVE FROM THE PLAINS TO NE
MN BY 12Z SAT. MODELS INDICATE THAT THE DRY SLOT UNDER THE JET SURGE
WILL DOMINATE...LIMITING PCPN CHANCES TO MAINLY DRIZZLE OR PATCHY
LIGHT RAIN. WITH A STEADY S WIND AND LINGERING LOW CLOUDS...EXPECT
STEADY OR SLOWLY RISING TEMPS THROUGH MUCH OF THE NIGHT AS THE COLD
FRONT ONLY APPROACHES THE FAR WEST BY AROUND 12Z. EXPECT AREAS OF
FOG AWAY FROM THE DOWNSLOPE AREAS NEAR LAKE SUPERIOR WITH MOIST LOW
LEVELS AND MELTING SNOW.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 545 AM EST FRI JAN 11 2013
TROF CONTINUES TO AMPLIFY OVER THE WRN CONUS AS PATTERN CHANGE IS
UNDERWAY. TROF WILL SLOWLY PROGRESS E OVER THE NEXT WEEK...THOUGH
WITH UNCERTAIN AMPLITUDE. MEDIUM RANGE GUIDANCE CONTINUES TO SHOW A
STRENGTHENING POLAR VORTEX WITH A GREATLY EXPANDING AND INTENSIFYING
ARCTIC AIR MASS AROUND HUDSON BAY NEXT WEEK. WITH BUILDING HEIGHTS
FORECASTED OVER GREENLAND...THERE SHOULD BE A TENDENCY FOR THE
BITTER COLD AIR TO SLIP INTO THE UPPER LAKES. HOWEVER...WITH PHASE
OF RECENTLY STRENGTHENED MJO FAVORING WARMTH OVER THE ERN CONUS...IT
WILL BE INTERESTING TO SEE HOW FAR S THE REALLY BITTER COLD AIR
SINKS NEXT WEEK IN RESPONSE TO THE DEVELOPING BLOCKING HIGH OVER
GREENLAND. AT LEAST FOR NOW...WOULD STILL BE SKEPTICAL OF ANY MODEL
SOLUTIONS SHOWING 850MB TEMPS NEARING -30C OVER UPPER MI OR SHOWING
ANYTHING MORE THAN A BRIEF INTRUSION OF BITTER COLD AIR GIVEN
COMPETING SIGNALS FOR WARMTH/COLD. SO...FCST WILL CONTINUE TO SHOW A
CONSERVATIVE APPROACH TO THE COLD WITH TEMPS GENERALLY CLOSE TO OR A
LITTLE BLO NORMAL NEXT WEEK. WITH SNOW COVER GETTING THIN IN MANY
AREAS AND NOT LIKELY TO INCREASE MUCH IF AT ALL AWAY FROM THE W AND
WNW WIND LES SNOW BELTS...THERE COULD BE PROBLEMS FOR WATER LINES IF
WE DO SEE ANYTHING MORE THAN JUST A SHORT DURATION OF SEVERE COLD.
AS JUST ALLUDED TO...PATTERN WILL BE A DRY ONE WITH LITTLE CHC FOR
ANY WIDESPREAD SYNOPTIC SNOW...BUT LES WILL BE A PERSISTENT FEATURE
OF THE FCST NEXT WEEK. IT APPEARS WESTERLY WINDS WILL PROBABLY
DOMINATE...PREVENTING MORE WIDESPREAD COVERAGE OF LES IN UPPER MI
MOST DAYS. THE KEWEENAW PENINSULA WILL SEE THE MOST SNOW FROM LES
NEXT WEEK...AND THERE MAY BE FAIRLY SUBSTANTIAL TOTALS FOR THE WEEK
THERE.
BEGINNING SAT...SHORTWAVE/SFC LOW WILL BE IN NE MN AT 12Z. AS SYSTEM
MOVES ENE THRU NRN ONTARIO DURING THE DAY...SHARP COLD FRONT WILL
CROSS UPPER MI. HOWEVER...SINCE STRONGEST DEEP LAYER QVECTOR
CONVERGENCE ACCOMPANYING DISTURBANCE PASSES TO THE N...AXIS OF MID
LEVEL DRY AIR IS FCST TO LINGER AND WILL LIKELY LEAD TO A DRY FROPA.
ONLY EXCEPTION MAY BE OVER THE W...CLOSER TO THE PASSING
DYNAMICS/DEEPER MOISTURE AND WHERE THE LOW-LEVEL FLOW WILL TAKE ON
MORE OF A CYCLONIC UPSLOPE COMPONENT...ESPECIALLY IN THE AFTN. 850MB
TEMPS FALLING TO AROUND -15C TOWARD 00Z SUN WILL ALSO ADD AN
INCREASING LES COMPONENT TO THE MIX. WITH WSW LOW-LEVEL WINDS...BEST
CHC FOR INCREASING -SHSN WILL BE OVER THE KEWEENAW. SHARP CAA (MAX
850MB TEMP FALL IS AROUND 10C IN 6HR) AND ISALLOBARIC WIND ALIGNED
WITH GRADIENT WIND (6MB/3HR PRES RISE FOLLOWING FROPA) WILL LEAD TO
WINDY CONDITIONS AFTER FROPA. SW WIND DIRECTION IS NOT TYPICALLY THE
MOST FAVORABLE DIRECTION FOR HIGH WINDS IN MOST LOCATIONS...BUT WITH
850MB WINDS AROUND 45KT...SOME GUSTS COULD APPROACH WIND ADVY
CRITERIA...MAINLY IN THE 1-3HRS DURING THE ISALLOBARIC WIND PUSH.
MOMENTUM TRANSFER SUGGESTS GUSTS OF 30-40MPH SHOULD GENERALLY BE THE
RULE FOR A FEW HRS AFTER FROPA. IN COMBINATION WITH FALLING SFC
TEMPS W TO E THRU THE DAY...THE AIR WILL BEGIN TO FEEL MUCH
COLDER...ESPECIALLY OVER THE W WHERE TEMP FALL WILL BE MOST
SIGNIFICANT.
SAT NIGHT THRU SUN NIGHT...AS COLDER AIR SETTLES INTO THE UPPER
GREAT LAKES...850MB TEMPS FALL INTO THE -16 TO -19C RANGE. LOOKS
LIKE A POTENTIALLY INTERESTING PERIOD OF LES AS GFS/NAM SHOW
MOISTURE PROFILE DEEPENING TO 10KFT OR MORE. WITH DEEP MOISTURE...
DENDRITIC SNOW GROWTH TEMPS FALLING FIRMLY INTO THE CONVECTIVE
LAYER...AND SFC TROF DRIFTING THRU THE AREA...THERE IS AN INCREASING
SIGNAL FOR MDT/HVY LES. SHOULD BE ABLE TO FLUFF UP SOME RATHER
SIGNIFICANT SNOW ACCUMULATIONS AS SNOW TO WATER RATIOS INCREASE TO
20-30 TO 1. THERE IS SOME UNCERTAINTY IN WIND DIRECTION WHICH WON`T
BE HANDLED WELL UNTIL CLOSER TO THE EVENT. OVERALL...MODELS INDICATE
A W TO WSW WIND SAT EVENING AHEAD OF TROF TO SHIFT WNW/NW SUN
MORNING AS SFC TROF PASSES. WITH SFC TROF APPROACHING...WOULD
EXPECT SAT NIGHT WINDS TO HAVE MORE OF A WSW/SW COMPONENT...
ESPECIALLY CONSIDERING LAND BREEZE COMPONENT WHICH SHOULD BE ACTIVE
AS LOW-LEVEL GRADIENT WINDS DIMINISH. THIS COULD LEAD TO A STRONG
CONVERGENCE ZONE/HVY LES SETTING UP FROM AROUND THE APOSTLE ISLANDS
INTO THE KEWEENAW SAT NIGHT. THE MDT/HVY SNOW WOULD THEN EXPAND TO
INCLUDE WNW/NW FAVORED SNOW BELTS FOR A TIME SUN. AT THIS POINT...
THE KEWEENAW PENINSULA APPEARS MOST LIKELY TO BE IMPACTED LONGEST BY
MDT/HVY LES. CONSIDERED A WATCH FOR KEWEENAW/NRN HOUGHTON COUNTIES
BEGINNING SAT NIGHT...BUT WILL LET NEXT SHIFT TAKE ANOTHER LOOK AS
WINDS MAY END UP MORE BACKED SAT NIGHT THAN CURRENTLY EXPECTED AHEAD
OF SFC TROF OR SFC TROF MAY PASS MORE QUICKLY THAN EXPECTED.
MON-THU...MOSTLY WEST WIND LES WILL CONTINUE. WHERE WINDS ARE
EXPECTED TO BE ONSHORE...OPTED FOR LIKELY/CATEGORICAL POPS DURING
THIS PERIOD. TUE IS ONLY DAY THAT MAY END UP DRY ACROSS UPPER MI AS
WINDS MAY BACK SUFFICIENTLY TO SHIFT LES OFFSHORE. OTHERWISE...
MEDIUM RANGE MODELS CONTINUE TO SHOW SIGNIFICANT
TIMING/TRACK/AMPLITUDE DIFFERENCES ON SHORTWAVES DROPPING SE INTO
THE GREAT LAKES NEXT WEEK TO THE S OF THE INTENSIFYING POLAR VORTEX
AROUND HUDSON BAY. ALSO...RUN-TO-RUN CONTINUITY WITH THE SHORTWAVES
REMAINS VERY POOR. SO...THERE`S NOT A LOT OF CONFIDENCE ON THE
SHORTWAVES AFFECTING THE AREA. IF ONE OF THE WAVES CAN AMPLIFY
SUFFICIENTLY...THEN BITTER COLD AIR WOULD PLUNGE INTO THE AREA.
WHETHER THAT HAPPENS REMAINS TO SEEN.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 635 PM EST THU JAN 10 2013
LINGERING DRY AIR WILL PRODUCE VFR CONDITIONS AT THE TAF SITES FOR
THE FIRST COUPLE OF HOURS. BROAD AREA OF RAIN CURRENTLY MOVING
NORTH THROUGH SOUTHERN WISCONSIN WILL BE MOVE ACROSS UPPER MICHIGAN
LATE THIS EVENING AND OVERNIGHT. THIS WILL DROP CEILINGS TO
IFR DURING THE OVERNIGHT HOURS...WITH SOME SITES AT ALTERNATE
LANDING MINIMUMS. BEHIND THE WAVE OF PRECIPITATION...WARM MOIST AIR
WILL LEAD TO LOW CLOUDS THROUGH THE REST OF THE PERIOD AND ALSO
SOME FOG. EXPECT THE FOG TO HAVE THE LOWEST VISIBILITIES AT KSAW
WITH THE FAVORABLE SSE FLOW INITIALLY AND THEN BACKING TO THE SW.
THERE MAY BE SOME SLIGHT LIFT TO THE CEILINGS ABOVE ALTERNATE
LANDING MINS TOMORROW AFTERNOON...BUT THEY WILL LIKELY GO BACK DOWN
AS THE SUN SETS AND FOG REDEVELOPS.
FINALLY...DID ADD A TEMPO FOR KSAW DURING THE FIRST COUPLE OF HOURS
DUE TO FAVORABLE UPSLOPE FLOW FROM THE CLOUDS FROM THE CLOUDS COMING
OFF LAKE MICHIGAN.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 545 AM EST FRI JAN 11 2013
A TIGHT PRESSURE GRADIENT BETWEEN AN APPROACHING LOW PRESSURE TROUGH
FROM THE NRN PLAINS AND A RIDGE OVER THE EASTERN GREAT LAKES WILL
RESULT IN SOUTH TO SOUTHEAST WINDS TO 25 KNOTS ACROSS THE ERN HALF
OF LAKE SUPERIOR THIS MORNING. WINDS SHOULD STAY AT OR BELOW 20 KTS
OVER THE WEST HALF. WINDS WILL DIMINISH BLO 20 KT FRI AFTERNOON AS
PRES GRADIENT WEAKENS.
WITH A WEAK PRES GRADIENT OVER THE LAKE THIS EVENING...EXPECT SSW WINDS
UNDER 20 KTS WINDS. BUT THE WINDS WILL INCREASE OVERNIGHT AS A DEEP
LOW PRESSURE SYSTEM MOVES NE FROM THE PLAINS INTO NE MN AND TIGHTENS
THE GRADIENT. EXPECT THE WINDS TO INCREASE RAPIDLY ON SAT AS A SHARP
COLD FRONT SLICES ACROSS THE UPPER GREAT LAKES AND THE ARRIVAL OF
MUCH COLDER AIR RESULTS IN DECREASING STABILITY AND GREATER MIXING OF
THE STRONGER WINDS TO THE LAKE SURFACE. A GALE WATCH WAS EXPANDED AS
GALES ARE EXPECTED ACROSS THE LAKE FROM SATURDAY MORNING INTO
SATURDAY EVENING. NOT OUT OF THE QUESTION THAT A FEW STORM FORCE
GUSTS COULD OCCUR OVER THE WRN LAKE AS WELL. THE COMBINATION OF THE
STRONG WINDS...COLDER AIR AND HIGHER WAVES WILL RESULT IN FREEZING
SPRAY AS WELL INTO SAT NIGHT WHEN THE WINDS WILL BE DIMINISHING WITH
THE DEPARTURE OF LOW PRES TO THE NORTHEAST. WINDS IN THE 15 TO 25 KT
RANGE ARE EXPECTED SUNDAY INTO MONDAY...BUT THE APPROACH OF ANOTHER
DISTURBANCE LATER ON TUE TUE AND NIGHT MIGHT RESULT IN W-SW WINDS
INCREASING TO GALES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
FREEZING RAIN ADVISORY UNTIL 7 AM EST /6 AM CST/ THIS MORNING
FOR MIZ001>007-009>011-084-085.
LAKE SUPERIOR...
GALE WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR
LSZ240>246-265>267.
GALE WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR
LSZ162-263-264.
LAKE MICHIGAN...
GALE WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR
LMZ221-248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...ROLFSON
AVIATION...SRF
MARINE...JLB
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1114 PM EST THU JAN 10 2013
.UPDATE...
ISSUED AT 1112 PM EST THU JAN 10 2013
ON SECOND THOUGHT...WILL GO AHEAD AND ISSUE FREEZING RAIN ADVISORY
FOR THE AREAS AWAY FROM THE WARMING OF LAKE MICHIGAN. APPEARS THAT
EVEN THOUGH TEMPERATURES ARE SEVERAL DEGREES ABOVE FREEZING...THE
BELOW FREEZING SURFACE TEMPS ARE ENOUGH TO CAUSE ICING ON SOME
ROADWAYS IN THOSE AREAS. WITH MIDOT SITES SHOWING ROAD SURFACE TEMPS
AROUND 28 IN IRON COUNTY AND SEVERAL REPORTS OF LIGHT ICING IN IRON
MOUNTAIN AND IRON RIVER...FEEL THAT THE CURRENT ADVISORY IS IN GOOD
SHAPE. TEMPS ARE FINALLY STARTING TO FALL IN IRONWOOD...DOWN TO
36...BUT WITH MIDOT ROAD SFC TEMPS IN TWIN LAKES AROUND 32...THOUGHT
IT WOULD BE A LITTLE MORE PATCHY THERE AND FOCUSED OVER FAR EASTERN
GOGEBIC COUNTY. LATEST OBSERVER REPORT INDICATED THAT MAIN ROADS WERE
WET BUT SECONDARY SNOW COVERED ROAD WAS SLICK. THUS...WILL KEEP THE
SPS GOING FOR FOR LOCATIONS OUTSIDE THE ADVISORY.
INITIAL WAVE OF PRECIPITATION SHOULD BE DIMINISHING FROM SOUTH TO
NORTH OVER THE WESTERN THIRD OF THE CWA OVER THE NEXT COUPLE OF
HOURS AND THEN WILL LIKELY SEE FOG/DRIZZLE FOR THE REST OF THE
NIGHT. OVER THE CENTRAL AND EASTERN CWA...SECOND WAVE OF
PRECIPITATION CURRENTLY EXITING NORTHERN ILLINOIS WILL BRING ANOTHER
PERIOD OF RAIN TOWARDS 08-13Z. SURFACE TEMPS WILL BE SLIGHTLY WARMER
AT THAT TIME...BUT STILL COULD SEE SOME ISSUES ON SECONDARY OR SNOW
COVERED ROADS.
PREVIOUS UPDATE
ISSUED AT 835 PM EST THU JAN 10 2013
FORECAST UPDATE MAINLY FOR POTENTIAL FREEZING RAIN THIS EVENING AND
TONIGHT. ONLY MADE MINOR TWEAKS TO THE GOING POPS TO FINE TUNE THE
SHARP START TO THE RAIN. WITH THE STRONG WARM AIR ADVECTION CREATING
A LARGE WARM LAYER ALOFT BASED ON RUC SOUNDINGS...THE PRECIPITATION
WILL FALL AS RAIN. THE QUESTION BECOMES WHAT WHILL HAPPEN ONCE IT
REACHES THE SURFACE. LOOKING AT MIDOT ROAD SENSORS ACROSS THE
CENTRAL CWA...SURFACE TEMPERATURES ARE AROUND 29-30 DEGREES.
THUS...THINKING THAT EVEN IF NEAR SURFACE TEMPERATURES ARE AT OR
JUST ABOVE FREEZING...THERE WILL STILL BE SOME FREEZING ON THE
LESSER TRAVELED ROADWAYS. THEREFORE...OPTED TO ISSUE A FREEZING RAIN
ADVISORY FOR IRON/DICKINSON COUNTIES AT THIS TIME DUE TO HAVING THE
HIGHEST CONFIDENCE FOR OCCURENCE. WAS ON THE EDGE FOR
BARAGA/MARQUETTE COUNTIES FOR THE HIGHER TERRAIN LOCATIONS THAT ARE
ALREADY HOVERING NEAR FREEZING. THE OTHER AREAS SHOULD ONLY SEE VERY
ISOLATED AREAS AND ISSUED AN SPS FOR THEM. HIGH RESOLUTION MODELS
SHOWING DOWNSLOPE WARMING HELPING OVER THE FAR WEST AND OFF LAKE
MICHIGAN OVER THE EAST. IN ADDITION...WITH TEMPS OUT WEST STILL
AROUND 40...DIDN/T FEEL COMFORTABLE ISSUING ONE FOR
GOGEBIC/ONTONAGON. EVEN THOUGH THOSE AREAS ARE WARMER...COLD GROUND
TEMPS COULD STILL PRODUCE SOME SLICK SPOTS.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 417 PM EST THU JAN 10 2013
TONIGHT...LATEST WATER VAPOR LOOP SHOWS WELL-DEFINED SHORTWAVE OVER
SRN OKLAHOMA. MODELS IN GOOD AGREEMENT ON TRACK OF THIS SHORTWAVE
WHICH IS FCST TO MOVE UP THE MS VALLEY LATER TONIGHT AND THEN INTO
THE LOWER GREAT LAKES ON FRIDAY. MODEL SNDGS CONSISTENT IN SHOWING
DEEP MOISTURE ARRIVING NOT UNTIL LATE THIS EVENING/OVERNIGHT...WITH
MOST PRECIPITATION HOLDING OFF ACROSS THE SOUTHERN CWA UNTIL AFT
03Z. COULD SEE SOME COOLING TO BELOW FREEZING TEMPS ACROSS INTERIOR
LOCATIONS OF THE CWA BEFORE CLOUDS THICKEN WITH THE ARRIVAL OF DEEP
MOISTURE...ESPECIALLY OVER THE WEST HALF WHERE DEWPOINTS ARE STILL
IN THE LOW TEENS AT MANY LOCATIONS. INITIALLY LOWER SFC WET-BULB
TEMPS DUE TO THIS DRIER AIRMASS COULD RESULT IN SOME LIGHT FREEZING
RAIN AT ONSET OF PCPN...BUT AS IN LINE WITH PREV FCST
THINKING...STILL EXPECT TEMPS TO WARM BACK TO IF NOT ABOVE FREEZING
SHORTLY AFTER ONSET OF PRECIPITATION. WITH SSE WINDS PUMPING IN
WARMER AND MORE MOIST AIR THROUGH THE OVERNIGHT HRS...BELIEVE ANY
FREEZING RAIN WILL BE SHORT-LIVED AND PCPN WILL EVENTUALLY TURN OVER
TO ALL RAIN LATER TONIGHT. SO FREEZING RAIN ADVISORY SHOULD NOT BE
NEEDED...BUT PERHAPS AN SPECIAL WEATHER STATEMENT MAY BE NEEDED FOR
EXPECTED SHORT DURATION EVENT.
MODELS STILL SEEM TO INDICATE THE BULK OF THE PRECIP WILL REMAIN
SOUTHEAST OF THE CWA...BUT BRIEF MODERATE RAINFALL COULD AFFECT THE
EAST HALF OF THE CWA AS A RESULT OF STRONG ISENTROPIC LIFT ALONG THE
295-305K SURFACES ON THE NOSE OF A 45-50 KT LLJ AS PRECIPITABLE
WATER VALUES SURPASS ONE INCH (450 PERCENT NORMAL) ACROSS THE EAST
HALF. HAVE SPREAD CATEGORICAL POPS ACROSS THE CWA FROM LATE EVENING
INTO EARLY OVERNIGHT HRS.
FRIDAY...SHORTWAVE PASSES WELL SOUTHEAST ALLOWING WEAK RDGG AND
Q-VECT DIV TO SPREAD IN FROM THE WEST....RESULTING IN DIMINISHING
RAIN CHCS FROM WEST TO EAST DURING THE DAY. DESPITE LINGERING LOW
CLOUDS...EXPECT MAX TEMPS FRI TO BE WELL ABOVE NORMAL GIVEN
UNSEASONABLE WARMTH TONIGHT AND CONTINUED LOW-LEVEL SSW FLOW AHEAD
OF WRN TROF THRU FRI.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 417 PM EST THU JAN 10 2013
FRI NIGHT...AS SHRTWV LIFTS NEWD OUT OF MEAN TROF OVER THE W HALF OF
NAMERICA...A SFC LO IS PROGGED TO MOVE FM THE PLAINS TO NE MN BY 12Z
SAT. THE FASTER 12Z NAM/CNDN MODELS SHOW ATTENDANT SFC COLD FNT
SWINGING THRU THE FAR W ARND IWD BY 12Z...BUT BULK OF OTHER GUIDANCE
INDICATES A SLOWER FROPA. MODELS INDICATE DRY SLOT UNDER THE JET
SURGE REGION ON THE ERN FLANK OF THE SHRTWV WL DOMINATE THRU THE
NGT...SO EXPECT GENERALLY DRY WX TO PREVAIL WITH ACCOMPANYING
DPVA/LARGER SCALE QVECTOR CNVGC/DEEPER MSTR ASSOCIATED WITH SHRTWV
IMPACTING MAINLY AREAS TO THE W OF UPR MI ON THE CYC SIDE OF THE
TRACK OF THIS DISTURBANCE. RETAINED SOME LO CHC POPS OVER THE LAND
CWA FOR THE POTENTIAL OF MAINLY SOME -DZ. WITH A STEADY S WIND AND
LINGERING LO CLD...EXPECT MIN TEMPS TO RUN WELL ABV NORMAL AGAIN...
EVEN IF SOME COLDER AIR ARRIVES OVER THE FAR W LATE BEHIND A FROPA.
THERE WL BE AREAS OF FOG AWAY FM THE DOWNSLOPE AREAS NEAR LK SUP
WITH MOIST LLVLS/MELTING SN.
SAT...AS SHRTWV/SFC LOW IN NE MN AT 12Z MOVES ENE THRU NRN
ONTARIO...SHARP COLD FRONT WILL CROSS UPPER MI. HOWEVER...SINCE
STRONGEST DEEP LAYER QVECTOR CONVERGENCE ACCOMPANYING DISTURBANCE WL
PASS TO THE N...AXIS OF MIDLVL DRY AIR IS FCST TO LINGER. WITH
ABSENCE OF DYNAMIC FORCING...FROPA SHOULD BE MAINLY DRY. ONLY
EXCEPTION MAY BE OVER THE W...CLOSER TO THE PASSING DYNAMICS/DEEPER
MOISTURE AND WHERE THE LLVL FLOW WILL TAKE ON MORE OF A CYC UPSLOPE
COMPONENT...ESPECIALLY IN THE AFTN. THE ARRIVAL OF H85 TEMPS ARND
-15C TOWARD 00Z SUN WILL ALSO ADD AN INCREASING LES COMPONENT TO THE
MIX. BUT MODELS HAVE TRENDED TOWARD A MORE WSW LLVL FLOW AND HOLDING
THE MORE IMPRESSIVE MOISTENING FARTHER TO THE W... SO LOWERED POPS
EVEN OVER THE FAR W EXCEPT FOR THE KEWEENAW. WITH ARRIVAL OF COLDER
AIR/DECREASING STABILITY...APRCH OF SHARP PRES RISE CENTER WITH
ISALLOBARIC WIND ALIGNED ALONG THE GRADIENT FLOW... AND SHARPENING
PRES GRADIENT ON THE SRN FLANK OF THE LO SHIFTING THRU NRN ONTARIO
THAT PUSHES H925 WINDS UP TO 25-35 KTS...IT WILL BE WINDY. IN
COMBINATION WITH FALLING SFC TEMPS W TO E THRU THE DAY... THE AIR WL
BEGIN TO FEEL MUCH COLDER...ESPECIALLY OVER THE W.
SAT NGT THRU SUN NGT...AS COLDER AIR POURS INTO THE UPR GREAT LKS...
H85 TEMPS ARE PROGGED TO FALL TO -16 TO -18C. PREVIOUS FCST LIKELY
POPS FOR LES LOOK ON TRACK IN AREAS FAVORED BY EXPECTED WNW FLOW
ALONG LK INDUCED TROF FCST TO EXTEND FM THE KEWEENAW INTO THE AREAS
E OF MQT. CONSIDERING THE MORE THAN SUFFICIENT THERMAL
INSTABILITY...DENDRITIC SNOW GROWTH TEMPS FALLING FIRMLY INTO THE
CONVECTIVE LAYER...AND RATHER DEEP MSTR SHOWN BY SOME OF THE
GUIDANCE ALONG THE TROF...MDT SNOW ACCUMS IN THE ADVY CATEGORY WL BE
PSBL IN THE FAVORED SN BELTS.
MON-THU...ALTHOUGH THE PERSISTENT UPR RDG OVER THE SE CONUS THAT
MAINTAINS MORE OF A CONFLUENT FLOW ALF BTWN THE SPLIT NRN/SRN
BRANCHES INTO THE GRT LKS WL LIMIT THE SPREAD OF ARCTIC AIR BOTTLED
UP IN CANADA EARLY IN THE EXTENDED PERIOD...A NUMBER OF THE EXTENDED
MODELS AND THEIR ENSEMBLE MEANS ARE HINTING A NRN BRANCH TROF
CENTERED OVER HUDSON BAY WL DEEPEN BY MID WEEK AS A SERIES OF
SHRTWVS PLUNGE INTO THE NCNTRL CONUS. CONFIDENCE IN THIS SCENARIO IS
INCREASED BY UPR RDG FCST TO BLD OVER GREENLAND WITH BLOCKING AT HI
LATITUDES. IF THIS NEGATIVE NAO PATTERN DOES INDEED DVLP...MUCH
COLDER ARCTIC AIR MAY SURGE INTO THE AREA ON WED/THU. IN FACT...THE
00Z ECWMF IS ADVERTISING H85 TEMPS IN THE -20C TO -25C RANGE BY THU.
AS FOR DAY TO DAY WX...MON/TUE MAY BE RELATIVELY QUIET WITH A WSW
LLVL FLOW ARND SFC HI PRES BRIEFLY ADVECTING SOMEWHAT MILDER AIR AND
LIMITING LES... H85 TEMPS ARND -10C...INTO THE UPR LKS. THE
COMBINATION OF PASSING SHRTWVS/ARRIVAL OF COLDER AIR WL THEN
INCREASE THE POTENTIAL FOR SGNFT LES ON WED/THU. TENDED HIER THAN
MODEL CONSENSUS POPS FOR THIS TIME PERIOD IN THE FAVORED SN BELTS.
OTRW...NO LARGE SCALE PCPN EVENTS APPEAR TO BE ON THE HORIZON.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 635 PM EST THU JAN 10 2013
LINGERING DRY AIR WILL PRODUCE VFR CONDITIONS AT THE TAF SITES FOR
THE FIRST COUPLE OF HOURS. BROAD AREA OF RAIN CURRENTLY MOVING
NORTH THROUGH SOUTHERN WISCONSIN WILL BE MOVE ACROSS UPPER MICHIGAN
LATE THIS EVENING AND OVERNIGHT. THIS WILL DROP CEILINGS TO
IFR DURING THE OVERNIGHT HOURS...WITH SOME SITES AT ALTERNATE
LANDING MINIMUMS. BEHIND THE WAVE OF PRECIPITATION...WARM MOIST AIR
WILL LEAD TO LOW CLOUDS THROUGH THE REST OF THE PERIOD AND ALSO
SOME FOG. EXPECT THE FOG TO HAVE THE LOWEST VISIBILITIES AT KSAW
WITH THE FAVORABLE SSE FLOW INITIALLY AND THEN BACKING TO THE SW.
THERE MAY BE SOME SLIGHT LIFT TO THE CEILINGS ABOVE ALTERNATE
LANDING MINS TOMORROW AFTERNOON...BUT THEY WILL LIKELY GO BACK DOWN
AS THE SUN SETS AND FOG REDEVELOPS.
FINALLY...DID ADD A TEMPO FOR KSAW DURING THE FIRST COUPLE OF HOURS
DUE TO FAVORABLE UPSLOPE FLOW FROM THE CLOUDS FROM THE CLOUDS COMING
OFF LAKE MICHIGAN.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 417 PM EST THU JAN 10 2013
A TIGHT PRESSURE GRADIENT BTWN APPROACHING LOW PRESSURE TROUGH FROM
THE NRN PLAINS AND A HIGH PRES RDG OVER THE ERN LAKES WILL RESULT IN
SOUTH TO SOUTHEAST WINDS TO 25 KNOTS ACROSS THE ERN HALF OF LAKE
SUPERIOR TONIGHT INTO FRI MORNING. WINDS SHOULD STAY AT OR BELOW 20
KTS OVER THE WEST HALF. A STRONG TEMPERATURE INVERSION ABOVE THE
SURFACE SHOULD KEEP STRONG WINDS ALOFT FROM MIXING TO THE
SURFACE...BUT A FEW GUSTS OVER 30 KNOTS OVER THE EAST HALF ARE NOT
OUT OF THE QUESTION. WINDS WILL DIMINISH BLO 20 KT FRI AFTERNOON AS
PRES GRADIENT WEAKENS.
WITH WEAK PRES GRADIENT OVER THE LAKE FRI EVNG...EXPECT SSW WINDS
UNDER 20 KTS WINDS. BUT THESE WINDS WILL INCREASE LATER FRI NIGHT
W-E AS A DEEP LO PRES SYSTEM MOVES NE FROM THE PLAINS INTO NE MN AND
SHARPENS THE GRADIENT. LOOK FOR THESE WINDS TO THEN INCREASE RAPIDLY
ON SAT AS THE SHARP COLD FRONT SLICES ACROSS THE UPPER GREAT LAKES
AND THE ARRIVAL OF MUCH COLDER AIR RESULTS IN DECREASING STABILITY/
GREATER MIXING OF THE STRONGER WINDS TO THE LAKE SURFACE. OPTED TO
HOIST GALE WATCH FOR THE W HALF GIVEN TERRAIN ENHANCED WSW FLOW AND
APPROACH OF PRES RISE CENTER THAT WILL SHARPEN THE LARGER SCALE
WINDS. THE COMBINATION OF THE STRONG WINDS/COLDER AIR/HIER WAVES
WILL RESULT IN FREEZING SPRAY AS WELL INTO SAT NIGHT WHEN THE WINDS
WILL BE DIMINISHING WITH DEPARTURE OF LO PRES TO THE NE/WEAKENING
GRADIENT. WINDS ON SUN INTO MON ARE FORECAST IN THE 15 TO 25 KT
RANGE FOR THE MOST PART...BUT THE APPROACH OF ANOTHER DISTURBANCE
LATER ON TUE/TUE NIGHT MIGHT RESULT IN W-SW WINDS INCREASING UP TO
30 KTS AND MORE FREEZING SPRAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
FREEZING RAIN ADVISORY UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR
MIZ001>007-009>011-084-085.
LAKE SUPERIOR...
GALE WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR
LSZ162-263-264.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...SRF
SHORT TERM...VOSS
LONG TERM...KC
AVIATION...SRF
MARINE...VOSS/KC
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
720 PM CST Sat Jan 12 2013
.UPDATE...
/714 PM CST Sat Jan 12 2013/
After intense late afternoon and early evening snow, it has really
diminished rapidly over most of the CWA. Snowfall reports have ranged
from 1-3 inches across the affected areas, with some locations...most
notably along the 50 hwy corridor reporting sporadic sleet and
freezing rain at the onset of precipitation before changing to all
snow. Rapid precip ending could be due in part to large area of dry
air to the west working in. HRRR has pegged this pretty good, and
even it has underestimated the decrease in precipitation to some
degree. As a result I have cancelled much of the western and northern
portions of the winter weather advisory, and will likely need to
cancel the rest of the advisory later this evening as the last of the
snow winds down.
Bailey
&&
.DISCUSSION...
Near Term (Through Tonight)...
Recent water vapor imagery shows a deepening positive tilt shortwave
trough ejecting across the TX/OK panhandle region, with an extensive
Pacific moist plume spreading northward from eastern Texas into the
Mid Mississippi valley region. Large scale ascent was rapidly
increasing within a broad area bound between the surface cold front
across central Arkansas and the trailing sloping frontal region that
extends back into SE Kansas through NE Missouri.
12Z upper air soundings showed a number of potential problems with
the near term forecast:
1.) Extensive dry air present both above and below the frontogenetic
region.
2.) A layer of 0 to +2C air lingering across the southern CWA
3.) Weak static stability (-EPV) present just above the mid level
frontogenesis region -- albeit in increasingly dry air.
Since 19Z, blossoming of echos on regional radar imagery confirms
large scale ascent associated with a 300mb jet streak was beginning
to overspread eastern KS/OK into MO/AR. Precipitation has been
largely showery in nature and has had difficulty reaching the ground
in the local CWA. Most of the initial virga sublimation will likely
aid in rapid top down saturation over the next 1-3 hours. Light snow
and sleet have been reported from the NWS office southward and this
is likely the beginning of tonight`s event. In the absence of
significant cold advection, diabatic cooling will likely be the
primary driving mechanism to eliminate the lingering warm nose, with
any PL over the far srn CWA going to all snow.
For this evening, 12Z models still indicate a rather strong coupling
between 850-600mb sloped frontogenesis and the upper jet streak.
Three big questions remain with this evening`s forecast. One being
the character of the snow, as stability parameters indicate we may
see elongated banding and a lack of uniformity. The second is the
primary moist axis feeding from srn Texas into AR and southern MO
which could perhaps drive more efficient precipitation south and
east of the local region. Lastly, the primary forcing occurs in
temperatures much warmer (-4 to -8C) than dendrite preference which
would reduce overall accumulations. With that said, the 1-3" painted
looks right on target with my analysis, with I-35 very near the
western bound of where frontogenetic forcing drops off rapidly.
Bottom line is that although this is a nuisance snow, amounts could
still vary quite a bit from locale to locale within that 1-3"
spectrum, and would not be surprised to see a slight buffer either
side of that range within the advisory area. Snow should taper off
quickly west to east after midnight as the subsidence overspreads
the area in the wake of the jet streak.
Bookbinder
Short Term (Sunday through Monday Night)...
Skies will clear from west to east on Sunday, with temperatures
really the only issue of concern through Monday Night. Readings will
largely be dictated by the axis of incoming high pressure and the
extent of snow cover once cold advection ceases by Monday morning.
Didn`t see any reason to stray too far from previous forecast.
Bookbinder
Medium Range (Tuesday through Saturday)...
A weakening, strongly tilted trough will gradually push east and
become enveloped by the northern jet stream toward the beginning of
the period, allowing the overall pattern to transition to a warmer,
more zonal flow across the central U.S. by the middle of next week.
Temperatures could still be a bit cool on Tuesday as the trough
departs, with most models indicating a lingering pocket of 850 mb
temperatures in the -7 to -9 degree range over northern Missouri. By
Wednesday, temperatures should rise to near or slightly above normal
values, with highs likely in the upper 30`s to mid 40`s for
Wednesday through Saturday. There remains a small possibility for
temperatures to be significantly colder on Thursday and Friday as
the trough over eastern Canada deepens, potentially allowing some
very cold air to filter into eastern portions of the CWA. This was
indicated yesterday by the EC and today by the GEM, but still
remains an outlying solution.
Precipitation is not expected through this period, with surface high
pressure generally dominating the central Plains and the jet stream
remaining well to the north.
Laflin
&&
.AVIATION...
For the 18Z TAFs, recent model guidance still suggests the bulk of
this evening`s winter weather event will likely skate just east of
the terminals with MKC seeings the greatest impacts of some
accumulating snow. A significant layer of dry air both above and
below a narrow corridor of strong elevated frontogenesis is the main
prohibiting factor.
VFR conditions will continue through 00Z with gradually lowering mid
cloud. Ceilings should steadily fall thereafter.
Basically have kept STJ dry, MCI on the fringe with MVFR to perhaps
brief IFR conditions this evening, and MKC in the steadier snow this
evening with IFR conditions likely. Conditions should rapidly
improve after around 07Z.
Winds will remain northwest to north-northwest at around 10 knots.
Bookbinder
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY until Midnight CST tonight FOR MOZ025-
031>033-038>040-044>046-054.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
405 PM CST FRI JAN 11 2013
.SHORT TERM...NOW THROUGH SATURDAY
...WINTERS COLD RETURNS TO THE CNTRL PLAINS TONIGHT WITH A PERIOD OF
STRONG WIND GUSTS IN THE TRANSITION...
AN SPS WAS ISSUED AT 2032Z FOR THE BLOWING DUST AND WILL PROBABLY
BE UPDATED BY THE BOTTOM OF THE HOUR.
WIND ADVISORIES CONTINUE AS POSTED. NPW WAS UPDATED/SENT AT 324 PM
TO RAISE ADDITIONAL AWARENESS OF BLOWING DUST OVER KS.
NOW: STRONG COLD FRONT IS SAGGING SE THRU CNTRL NEB. IT WAS LAST
SEEN ON THE LNX 88D AT 1825Z JUST NW OF BBW. THE TIMING TOOL BRINGS
IT INTO GRI BY 2230Z. 992 MB LOW WAS TRACKING ALONG THE KS-NEB
BORDER...S OF WHERE IT WAS FCST 24 HRS AGO.
THE FRONT IS AHEAD OF SCHEDULE SO USED THE RAP FOR SHORT-TERM WINDS.
THE 18Z RAP SUGGESTS IT FINALLY CUTS NE THIS EVNG ACROSS ERN NEB.
BLOWING DUST: A BURST OF 33-41 KT WINDS HAS RESULTED IN A LARGE AREA
OF BLOWING DUST THAT ORIGINATED OVER ERN CO. TIMING TOOL WILL BRING
THIS INTO OUR KS COUNTIES AROUND 445 PM AND IT WILL CONTINUE UNTIL
WIND SHIFT ASSOCIATED WITH COLD FRONTAL PASSAGE.
CONTEMPLATED CANCELLING THE WIND ADVISORY FOR N-CNTRL KS SINCE WINDS
HAVE BEEN WELL BELOW ADVISORY SUSTAINED OR GUSTS. BUT GIVEN MULTIPLE
G40 KTS WITH THAT DUST...HAVE CONTINUED ADVISORY.
A LARGE AREA OF STRATUS IS EXPECTED TO SINK S BEHIND THE FRONT TNGT
IN THE WAKE OF THE DEPARTING LOW. HOW FAR S OVC EXTENDS REMAINS
UNCERTAIN GIVEN DOWNSLOPING WINDS WILL TEND TO BREAK IT UP.
WIND: 3 HR PRES RISES ARE ONLY 3 MB OVER THE NEB PANHANDLE AT 21Z.
THE NAM IS OVER ESTIMATING THIS BY 5 MB AND THE RAP BY 3 MB. THINK
THE TREND IS RIGHT WITH EXPANDING/INCREASING PRES RISES AS THE LOW
ACCELERATES NEWD THIS EVE...BUT THE MAGNITUDE MAY BE OVERDONE.
CONFIDENCE IS ABOVE AVERAGE FOR VERIFYING THE ADVISORY OVER N-CNTRL
KS AHEAD OF THE FRONT. IT/S TAKEN ALL DAY BUT IT WILL VERIFY
22Z-03Z. BEHIND THE FRONT HAVE YET TO SEE ADVISORY LEVEL WINDS
DEVELOP. LOW-LEVELS WILL BECOME UNSTABLE IN CAA THIS EVE AND BUT
THIS APPEARS A MARGINAL WIND EVENT SO VERIFYING NEB WIND ADVISORY IS
BELOW AVERAGE ALONG AND S OF I-80. BEST CHANCE FOR A ONE-TIME 45 MPH
GUST WILL BE N OF THE TRI-CITIES. THE BEST CHANCE FOR VERIFYING
ALONG AND S OF I-80 WILL PROBABLY BE A BRIEF PERIOD OF SUSTAINED
WINDS OF 30 MPH.
TNGT: M/CLOUDY WITH BLUSTERY NW WINDS. SOME FLURRIES OR BRIEF SHSN
WILL OCCUR 6PM-12AM IN PULSE OF CAA. TEMP GUIDANCE WAS IN GOOD
AGREEMENT AND USED THE CONSENSUS OF ALL GUIDANCE WHICH BASICALLY
PUTS TEMPS NEAR NORMAL.
SAT: A MIX OF CLOUDS/SUN. UNSURE HOW MUCH STRATOCU GETS TRAPPED
UNDER FRONTAL INVERSION. HAVE ALREADY INCREASED CLOUDS ABOVE
PREVIOUS GID FCST AND IF NAM BUFKIT IS RIGHT THAN WE WILL BE TOO
LOW ON CLOUD COVER. REGARDLESS...PATCHES JET STREAM CIRRUS WILL
KEEP THE SKY AT LEAST P/CLOUDY. STILL A BLUSTERY NW WIND WITH GUST
UP TO 30 MPH FORENOON. TEMPS ARE NAM 2M TEMPS WHICH IS CLOSE TO
THE PREVIOUS FCST...ABOUT 12F BELOW NORMAL.
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY. THIS WILL LIKELY BE A
DRY PERIOD WITH TEMPERATURES GENERALLY WARMING THROUGH AT LEAST
WEDNESDAY. MORE UNCERTAINTY ENTERS THE PICTURE BY THURSDAY AND
FRIDAY.
SATURDAY NIGHT THROUGH MONDAY...A COLD AREA OF ARCTIC HIGH PRESSURE
WILL BEGIN TO SLIDE INTO THE PLAINS SATURDAY NIGHT INTO SUNDAY AND
REMAIN THROUGH AT LEAST MONDAY. THERE WILL BE A LARGE UPPER TROUGH
SITUATED OVER THE PLAINS BUT ALL OF THE MOISTURE WILL BE AT THE
LEADING EDGE OF THIS TROUGH AND WELL OFF TO OUR EAST. HIGH
TEMPERATURES WILL BE STUCK IN THE 20S ON SUNDAY AND POSSIBLY MONDAY
AS WELL. SOME AREAS THAT ARE COMPLETELY FREE OF SNOW COVER MAY REACH
THE LOWER 30S ON MONDAY.
TUESDAY AND WEDNESDAY...THE 12Z ECMWF PUSHES THE SFC HIGH OFF TO OUR
SOUTH ALLOWING FOR WEST SOUTHWEST DOWNSLOPE SFC WINDS. THE SHALLOW
COLD AIR WILL GRADUALLY MODERATE WITH HIGH TEMPERATURES BACK INTO
THE 30S ON TUESDAY AND PROBABLY 40S BY WEDNESDAY.
THURSDAY THROUGH FRIDAY...THERE IS A SUBSTANTIAL AMOUNT OF MODEL
UNCERTAINTY WITH REGARD TO TEMPERATURES. HOWEVER...THERE IS GOOD
MODEL AGREEMENT IN DRY CONDITIONS. THE ECMWF BRINGS A COLD FRONT
THROUGH WEDNESDAY NIGHT WITH STRONG COLD AIR ADVECTION ON THURSDAY.
THE 850 MB TEMPERATURES THURSDAY EVENING RANGE FROM -15C ON THE 12Z
ECMWF TO 5C ON THE 12Z GFS FOR A SIGNIFICANT 20C DEGREE SPREAD. THE
OFFICIAL FORECAST IS SOMEWHERE IN THE MIDDLE OF THESE TWO MODELS
CALLING FOR ABOVE FREEZING HIGHS IN THE UPPER 30S TO LOWER 40S.
HOWEVER...THESE HIGHS MAY VERY WELL BE TOO WARM. THE ONGOING
STRATOSPHERIC WARMING EVENT WILL LIKELY RESULT IN THE TRANSITION TO
A NEGATIVE ARCTIC OSCILLATION PATTERN...WHICH TENDS TO BRING THE
COLD AIR DOWN OUT OF CANADA INTO THE EASTERN TWO THIRDS OF THE
CONUS. THEREFORE...I WOULD LEAN MORE TOWARDS THE ECWMF AND THE
POSSIBILITY OF COLDER TEMPERATURES THAN WHAT WE ARE OFFICIALLY
CALLING FOR AS THIS BETTER FITS THE -AO PATTERN. IF THE 12Z ECMWF
COLDER TREND CONTINUES...WE WILL NEED TO BE LOWERING OUR THURSDAY
AND FRIDAY HIGH TEMPERATURES.
&&
.PREV DISCUSSION... /ISSUED 1230 PM CST FRI JAN 11 2013/
AVIATION...(18Z GRI TAF THROUGH 18Z SATURDAY AFTERNOON)
THIS AFTN: VLIFR VSBY HAS IMPROVED AND CONTINUED IMPROVEMENT IS
EXPECTED. HOWEVER...LIFR/IFR STRATUS CIGS MAY CONTINUE FOR THE
REST OF THE DAY. CURRENTLY THE TAF IS OPTIMISTIC WITH VFR
CIGS/VSBYS BY 1930Z. STRATUS IS DECREASING FROM THE S /HSI IS VFR/
BUT INCREASING FROM THE N. EXPECT LIGHT S WINDS TO CONTINUE.
TNGT: MVFR CIGS. A COLD FRONT IS JUST N OF THE TERMINAL. THIS
FRONT WILL MOVE THRU AROUND 01Z WITH A WIND SHIFT. COULD SEE A
BRIEF BURST OF MVFR FLURRIES BUT CONFIDENCE IS NOT HIGH ENOUGH TO
INCLUDE IN TAF. WNW WINDS WILL GUST TO 35-40 KTS BETWEEN 01-08Z
WITH A ONE-TIME PEAK GUST OF 45 KTS POSSIBLE. HAVE INDICATED MVFR
CIGS BUT COULD BEGIN AS IFR CIGS WITH GRADUAL IMPROVEMENT TO MVFR.
STRONGEST WINDS SUBSIDE BY 08Z.
SAT THRU 18Z: MVFR CIGS. VSBYS UNRESTRICTED. NW WINDS 15-25 KTS.
CIG CONFIDENCE: BELOW AVERAGE THRU 03Z THEN AVERAGE
VSBY CONFIDENCE: AVERAGE THRU 21Z THEN HIGH
WIND CONFIDENCE: AVERAGE
WX CONFIDENCE: HIGH
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY FROM 8 PM THIS EVENING TO 1 AM CST SATURDAY FOR
NEZ039>041-046>049-060>064-074>077.
KS...WIND ADVISORY UNTIL 10 PM CST THIS EVENING FOR KSZ005-006-
017>019.
&&
$$
SHORT TERM...HALBLAUB
LONG TERM...WESELY
AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
730 AM EST FRI JAN 11 2013
.SYNOPSIS...
HIGH PRESSURE EXTENDING ACROSS THE AREA THIS MORNING WILL TODAY. A
WARM FRONT WILL LIFT NORTHWARD ACROSS CENTRAL NC THIS AFTERNOON AND
TONIGHT. HIGH PRESSURE ANCHORED OFF THE GEORGIA-NORTHEAST FLORIDA
COAST WILL BRING SPRING LIKE TEMPERATURES TO THE CAROLINAS THIS
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 730 AM FRIDAY...
WITHIN AN AMPLIFIED LONGWAVE PATTERN OVER THE CONUS...THE REMNANTS
OF THE UPPER THAT WAS OVER TX YESTERDAY IS NOW LIFTING NORTHEAST
ACROSS THE MID MS RIVER VALLEY REGION...WHILE A 1034MB SURFACE HIGH
OVER NEW ENGLAND EXTENDS SOUTH INTO THE CAROLINAS. STRENGTHENING
LOW LEVEL FLOW ON THE EASTERN FLANK OF THE LLJ OVER TN/KY IS LEADING
TO INCREASING WARM ADVECTION AND ISENTROPIC ACCENT ATOP THE SURFACE
RIDGE AXIS OVER CENTRAL NC THIS MORNING. THE SHALLOW LIFT WILL BE
MAXIMIZED THROUGH 15Z OVER THE WESTERN CWA...SHIFTING AND WEAKENING
TO THE NORTH AND EAST THIS AFTERNOON. MOST OF THE ECHOES CURRENTLY
SHOWING UP ARE NOW STARTING TO REACH THE GROUND...WITH MORE AND MORE
SITES REPORTING LIGHT RAIN OR DRIZZLE. BASED ON RAP SOUNDINGS...
MOISTURE IS MOSTLY FOCUSED BELOW THE FREEZING LEVEL AND EVEN AS THE
AXIS OF DEEPER MOIST AXIS ASSOCIATED WITH THE AFOREMENTIONED
SHORTWAVE SHIFTS EAST ACROSS THE MOUNTAINS THIS MORNING...MOISTURE
NEAR -10C WILL BE VERY LIMITED. THUS...LIKELY POPS FOCUSED OVER THE
WESTERN HALF OF THE CWA WILL MAINLY BE FOR EVERY LIGHT RAIN/DRIZZLE
WITH ONLY A TRACE OR A FEW HUNDREDTHS OF QPF.
THIS LACK OF SIGNIFICANT PRECIP MAKES THE HIGH TEMP FORECAST MORE
CHALLENGING...AS THE WEDGE AIRMASS RESULTING FROM LIGHT PRECIP
FALLING INTO THE DRY SURFACE RIDGE SHOULD BE SHALLOW..ON THE ORDER
OF 1000-2000FT. THE WARM ADVECTION ABOVE THE INVERSION SHOULD
INITIALLY HELP TO STRENGTHEN THE WEDGE AIRMASS...BUT FORECAST
SOUNDINGS DO SHOW SOME TOP-DOWN EROSION BEGINNING THIS
AFTERNOON....AND THE SOURCE OF DRY NORTHEASTERLY FLOW WILL BE LOST
AS THE PARENT HIGH SHIFTS OFF THE NEW ENGLAND COAST LATER TODAY. THE
CHALLENGING QUESTION IS HOW QUICKLY THE WEDGE FRONT WILL MIX NORTH
AND WEST ACROSS THE AREA. WILL STILL SHOW A RANGE OF 50-68 FROM
NORTHWEST TO SOUTHEAST....THOUGH LINGERING PRECIP OVER THE NORTHEAST
PIEDMONT MAY HOLD TEMPS DOWN A LITTLE MORE THAN PREVIOUSLY FORECAST.
THE COVERAGE OF LIGHT RAIN WILL DECREASE LATE THIS AFTERNOON AND
SHOULD TRANSITION TO ONLY DRIZZLE OVER THE NORTHWEST PIEDMONT BY
00Z. DRYING ALOFT SHOULD ALLOW AREAS OF (DENSE)FOG TO FORM TONIGHT
WHERE WINDS ARE LIGHTEST...WITH THE HIGHEST SREF PROBABILITY WITHIN
THE REMNANT WEDGE AIRMASS. LOWS IN THE UPPER 40S TO MID 50S.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 310 AM FRIDAY...
SATURDAY/SATURDAY NIGHT...
IF THE LINGERING...SHALLOW WEDGE AIRMASS IS INDEED CONFINED TO ONLY
THE FAR NORTHWEST PIEDMONT BY SATURDAY MORNING...THEN MOST OF THE
CWA WILL HAVE LITTLE TROUBLE BREAKING OUT AS A STRONG DEEP LAYER
RIDGE BUILDS BACK ACROSS THE SOUTHEAST US. MODELS DO SHOW SOME
LINGERING MOISTURE IN THE 850-700MB LAYER...SO A FAIR AMOUNT IF
CLOUD COVER WILL KEEP HIGHS FROM REACHING THEIR FULL HEATING
POTENTIAL AS THICKNESSES SOAR WELL ABOVE 1380M. WILL ERR ON THE
SLIGHTLY COOLER SIDE OF STATISTICAL GUIDANCE..WHICH IS STILL SOLIDLY
IN THE LOW TO MID 70S ACROSS THE CWA. A COLD FRONT WILL BEGIN TO
APPROACH THE APPALACHIANS FROM THE WEST SATURDAY NIGHT. WITH A WEAK
PRESSURE GRADIENT EAST OF THE MOUNTAINS AND LINGERING LOW LEVEL
MOISTURE...STRATUS AND FOG MAY BE ISSUES ONCE AGAIN. LOWS WILL BE
UNSEASONABLY MILD IN THE 50S.
FOR SUNDAY/SUNDAY NIGHT: CONTINUED WARM AND GENERALLY DRY. THE
SURFACE AND MID LEVEL LONGWAVE RIDGE AXIS WILL BE ALIGNED JUST OFF
THE EAST COAST EARLY SUNDAY... WITH A MILD SOUTHWESTERLY SURFACE
FLOW AHEAD OF THE WAVY SURFACE COLD FRONT... EXPECTED TO STRETCH
ALONG THE WEST SLOPES OF THE APPALACHIANS. THE MID LEVEL FLOW FROM
THE SW REMAINS FAIRLY FLAT WITH ANY PERCEPTIBLE PERTURBATIONS
HOLDING WELL TO OUR NORTHWEST... AS SHOULD THE UPPER JET CORE AND
LOW LEVEL JET. WITH A LACK OF MECHANISMS TO FORCE ASCENT OVER
CENTRAL NC AND A FAIRLY LIGHT DIFFLUENT LOW LEVEL FLOW... MOST IF
NOT ALL PRECIP SHOULD HOLD NORTHWEST OF THE CWA THROUGH SUNDAY
NIGHT... AND INDEED THE MODEL CROSS SECTIONS REVEAL AN ANAFRONTAL
STRUCTURE WITH SLOPED ASCENT INTO THE COLD AIR OVER AND WEST OF THE
MOUNTAINS. SREF PROBABILITIES ALSO SHOW SINGLE-DIGIT CHANCES OF
MEASURABLE RAIN IN CENTRAL NC THROUGH SUNDAY NIGHT. LOW LEVEL
THICKNESSES REMAIN NEARLY 70 METERS ABOVE NORMAL... ALTHOUGH THIS
LAYER DOES ENCOMPASS A PORTION OF THE WARM NOSE ALOFT AND THUS
SOMEWHAT OVERREPRESENTS THE SURFACE WARMTH. THAT SAID... PREDICTED
925 MB TEMPS OF +15C TO +16C DO SUPPORT HIGHS INTO THE LOWER-MID
70S. FACTORING IN AT LEAST PARTLY CLOUDY SKIES WITH FLAT STRATOCU...
AND CONSIDERING THE MODEL DIFFERENCES WITH THE GFS CLOUDIER AND
COOLER IN THE WEST... EXPECT HIGHS TO RANGE FROM 71 NORTHWEST TO 76
IN THE EAST... LIKELY JUST SHY OF THE RECORD HIGHS. EXPECT AREAS OF
FOG AND LOW STRATUS SUNDAY NIGHT... AND THIS PLUS THE STEADY SW
BREEZE OVERNIGHT SHOULD KEEP TEMPS QUITE MILD OVERNIGHT... DROPPING
NO LOWER THAN 54-58... IN ACCORDANCE WITH LOCAL RESEARCH SHOWING
THAT STATISTICAL GUIDANCE LOWS IN PREFRONTAL WARM-ADVECTION
SCENARIOS ARE OFTEN TOO COOL. -GIH
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 255 AM FRIDAY...
A PATTERN CHANGE IS IN THE OFFING FOR NC THIS WEEK... AS THE RECENT
AND UPCOMING WARM PATTERN WILL BE SUPPLANTED BY AN INFLUX OF COLDER
CANADIAN-SOURCE AIR.
FOR MONDAY/MONDAY NIGHT: HEWING CLOSELY TO THE ECMWF SOLUTION...
WHICH AGREES FAIRLY WELL WITH BOTH THE EC AND GFS ENSEMBLE MEAN...
EXPECT ONE MORE MILD DAY. HOWEVER... THE STEADY SUCCESSION OF
WEAKENING WAVES TRACKING NE UP THE WEST SIDE OF THE RIDGE THROUGH
THE GREAT LAKES COMBINED WITH THE SSE DROP OF THE POLAR VORTEX FROM
NUNAVUT INTO HUDSON BAY WILL HELP SLIGHTLY TILT AND WEAKEN THE WRN
ATLANTIC RIDGE... SUCH THAT THE SURFACE FRONT WILL ALSO PIVOT MORE
SW-TO-NE AND INCH INTO WRN AND NW NC BY LATE MONDAY NIGHT... LEADING
TO IMPROVING RAIN CHANCES THERE. THE ECMWF HAS BEEN A BIT SLOWER AND
THUS DRIER THROUGH MONDAY NIGHT AS COMPARED TO THE GFS... HOWEVER
THE ECMWF HAS BEEN TRENDING A LITTLE FASTER AND ITS MOST RECENT RUN
BRINGS RAIN WELL INTO THE FORECAST AREA LATE AFTERNOON THROUGH THE
NIGHT. WILL CARRY A CHANCE OF SHOWERS... HIGHER OVER THE WRN AND NRN
FRINGE OF THE FORECAST AREA... FROM MIDDAY THROUGH MONDAY NIGHT.
HAVE TRIMMED HIGHS BACK A BIT IN THE NRN/WRN CWA... AND NOW HAVE
HIGHS OF 65-73. WITH EXPECTATIONS OF THE FRONT DIPPING SLIGHTLY PAST
THE NC/VA BORDER AS A BACKDOOR FRONT LATE MONDAY NIGHT AS THE ECMWF
SUGGESTS... WE SHOULD SEE LOWS RANGING FROM NEAR 50 IN THE NORTH TO
THE MID-UPPER 50S SOUTH OF HIGHWAY 64.
FOR TUESDAY/TUESDAY NIGHT: IT APPEARS INCREASINGLY LIKELY THAT THE
BACKDOOR FRONT WILL MAKE GOOD SOUTHWARD PROGRESS WELL INTO NC EARLY
TUESDAY... PROPELLED BY THE COOLER DENSE SURFACE HIGH OVER THE
CENTRAL CONUS AS WELL AS THE STRENGTHENING AND SOUTHWARD EXPANSION
OF THE POLAR VORTEX TO ENVELOP THE ST LAWRENCE VALLEY/GREAT LAKES/
NORTHEAST STATES BY EARLY WEDNESDAY. THE ECMWF TAKES A 25 KT SWRLY
LOW LEVEL JET UP ACROSS CENTRAL/ERN NC... ENHANCING MOIST UPGLIDE
AND SUBSEQUENTLY THE LIFT AND PRECIP OVER CENTRAL NC TUESDAY
AFTERNOON... IN CONJUNCTION WITH INCREASING HIGHER LEVEL LIFT IN THE
RIGHT ENTRANCE REGION OF A 150+ KT JET ACROSS THE NORTHEAST STATES.
WITHOUT GETTING TOO PRECISE IN THE DETAILS WHICH COULD STILL BE OFF
AT THIS TIME RANGE... WILL DEPICT AN INCREASE IN RAIN CHANCES ON
TUESDAY AS THE FRONT DROPS THROUGH. WE MAY IN FACT SEE TEMPS FALLING
DURING THE DAY ESPECIALLY IN THE NORTHERN HALF AS THE RAIN FALLS
INTO THE INCOMING CHILLY AIR MASS. HAVE CUT BACK HIGHS TO RANGE FROM
54 NORTH TO 68 SOUTHEAST... AND EVEN THIS COULD BE TOO WARM IN THE
NORTH. THOSE WITH PLANS ON TUESDAY SHOULD MONITOR OUR LATER
FORECASTS... AS THIS MAY END UP TURNING INTO QUITE A COOL/RAW/CLOUDY
AND POSSIBLY RAINY AFTERNOON. LOWS TUESDAY NIGHT 44-51 AS THE FRONT
DROPS TO OUR SOUTH AND COOLER AIR CONTINUES TO FILTER IN BENEATH
CONSIDERABLE CLOUD COVER.
FOR WEDNESDAY THROUGH THURSDAY: MODELS DIFFER IN THEIR HANDLING OF A
CLOSED LOW EXPECTED TO FORM OVER THE DESERT SOUTHWEST BY TUESDAY.
BOTH THE OPERATIONAL GFS AND ECMWF WEAKEN IT SLIGHTLY AND TAKE IT
EASTWARD INTO THE LOWER MISS VALLEY... WITH THE GFS MORE OF AN OPEN
WAVE AND ABOUT 12 HRS FASTER THAN THE ECMWF. THIS APPROACH WILL TEND
TO FLATTEN OUT THE INITIAL CYCLONIC MID LEVEL FLOW OVER THE MID
SOUTH AND MIDATLANTIC... ALLOWING THE FRONT TO NUDGE A BIT BACK
NORTHWARD TOWARD NC AND POTENTIALLY PROVIDING A FOCUS FOR LIFT ALONG
AND NORTH OF THE FRONT. BUT THERE ARE FAR TOO MANY QUESTION MARKS
REGARDING HOW MUCH MOISTURE WOULD BE AVAILABLE... EXACTLY WHERE THE
FRONT MIGHT END UP DURING THIS TIME FRAME... AND HOW MUCH (IF ANY)
THE POLAR STREAM WILL INFLUENCE THIS PATTERN... CRUCIAL CONSIDERING
THE GFS/ECMWF GREATLY DIVERGE WITH THEIR HANDLING OF THE POLAR
VORTEX. WILL KEEP TEMPS WITHIN A CATEGORY OF NORMAL FOR NOW... WITH
JUST SMALL CHANCE POPS UNTIL THE PICTURE BECOMES MORE CLEAR. -GIH
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 640 AM FRIDAY...
CURRENT TAF PERIOD...
ADVERSE AVIATION CONDITIONS HAVE DEVELOPED THIS MORNING AS PATCHY
LIGHT RAIN MOVES SOUTH TO NORTH ACROSS CENTRAL NC. CEILINGS VARY
FROM IFR OVER THE WESTERN PIEDMONT TO MVFR TOWARD KRWI AND
KFAY...WITH SOME POCKETS OF MVFR VSBYS IN THE HEAVIER RAIN/DRIZZLE.
AS THE PRECIP CONTINUES TO SPREAD NORTH AND EVENTUALLY NORTHEAST
THIS MORNING...CEILINGS AND VSBYS SHOULD REMAIN FAIRLY UNCHANGED
THROUGH MIDDAY...ALTHOUGH LIFR CEILINGS COULD STILL DEVELOP OVER THE
NORTHWEST PIEDMONT. THERE IS IS A CHANCE THAT SOUTHERLY LOW LEVEL
WINDS WILL BE ABLE TO MIX OUT SOME OF THE LOW CLOUDS NEAR KFAY AND
KRWI...LEADING TO MVFR CEILINGS DURING THE AFTERNOON.
HOWEVER...CONFIDENCE IN THIS HAPPENING IS ONLY MODERATE...WITH MUCH
LOWER CONFIDENCE TO THE WEST AT KRDU. LIGHT AND VARIABLE OR
NORTHEASTERLY WINDS CAN BE EXPECTED AT KGSO/KINT...WITH WINDS
SWITCHING TO SOUTHERLY THIS AFTERNOON AT KFAY AND KRWI. BORDERLINE
LOW LEVEL WIND SHEAR CRITERIA WILL BE POSSIBLE THIS MORNING AT
KGSO/KINT/KRDU. WINDS ARE AROUND 30KT JUST ABOVE 2000 FT...BUT THE
INVERSION MAY NOT YET BE SHARP ENOUGH FOR A 20KT CHANGE OVER 200
FT...EVEN WITH VEERING WIND PROFILES. THE INVERSION IS EXPECTED TO
STREGTHEN BY MIDDAY...THOUGH AT THE SAME TIME WINDS ABOVE THE
SURFACE WEAKEN.
SUB-VFR CEILINGS SHOULD PERSIST OVERNIGHT AND INTO MID-MORNING
SATURDAY. MEANWHILE...AS DRIER AIR ALOFT MOVES ACROSS THE AREA
TONIGHT...AREAS OF FOG ARE LIKELY TO DEVELOP...WITH DENSE FOG AND
POSSIBLE AFTER MIDNIGHT.
OUTLOOK...
WHILE CONDITIONS ARE EXPECTED TO IMPROVE BY MIDDAY SATURDAY...LOW
VSBYS AND CEILINGS WILL BE POSSIBLE AGAIN SATURDAY NIGHT. VFR
CONDITIONS WILL THEN REDEVELOP ON SUNDAY. THE NEXT CHANCE OF
WIDESPREAD SUB-VFR CONDITIONS WILL BE LATE MONDAY THROUGH TUESDAY AS
A COLD FRONT MOVES INTO THE AREA FROM THE WEST.
&&
.CLIMATE...
RECORD TEMPERATURE INFORMATION FOR JANUARY 12/13/14:
JAN 12TH RECORD HIGHS-
RDU: 76 (1890)
GSO: 76 (1907)
FAY: 77 (1916)
JAN 13TH RECORD HIGH MIN TEMPS-
RDU: 61 (2005)
GSO: 61 (1932)
FAY: 59 (2005)
JAN 13TH RECORD HIGHS-
RDU: 78 (2005)
GSO: 76 (1911)
FAY: 79 (2005)
JAN 14TH RECORD HIGH MIN TEMPS-
RDU: 61 (1995)
GSO: 59 (1995)
FAY: 62 (1972)
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...SMITH
SHORT TERM..SMITH/HARTFIELD
LONG TERM...HARTFIELD
AVIATION...SMITH
CLIMATE...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
650 AM EST FRI JAN 11 2013
.SYNOPSIS...
HIGH PRESSURE EXTENDING ACROSS THE AREA THIS MORNING WILL TODAY. A
WARM FRONT WILL LIFT NORTHWARD ACROSS CENTRAL NC THIS AFTERNOON AND
TONIGHT. HIGH PRESSURE ANCHORED OFF THE GEORGIA-NORTHEAST FLORIDA
COAST WILL BRING SPRING LIKE TEMPERATURES TO THE CAROLINAS THIS
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM FRIDAY...
WITHIN AN AMPLIFIED LONGWAVE PATTERN OVER THE CONUS...THE REMNANTS
OF THE UPPER THAT WAS OVER TX YESTERDAY IS NOW LIFTING NORTHEAST
ACROSS THE MID MS RIVER VALLEY REGION...WHILE A 1034MB SURFACE HIGH
OVER NEW ENGLAND EXTENDS SOUTH INTO THE CAROLINAS. STRENGTHENING
LOW LEVEL FLOW ON THE EASTERN FLANK OF THE LLJ OVER TN/KY IS LEADING
TO INCREASING WARM ADVECTION AND ISENTROPIC ACCENT ATOP THE SURFACE
RIDGE AXIS OVER CENTRAL NC THIS MORNING. THE SHALLOW LIFT WILL BE
MAXIMIZED THROUGH 15Z OVER THE WESTERN CWA...SHIFTING AND WEAKENING
TO THE NORTH AND EAST THIS AFTERNOON. MOST OF THE ECHOES CURRENTLY
SHOWING UP ARE NOW STARTING TO REACH THE GROUND...WITH MORE AND MORE
SITES REPORTING LIGHT RAIN OR DRIZZLE. BASED ON RAP SOUNDINGS...
MOISTURE IS MOSTLY FOCUSED BELOW THE FREEZING LEVEL AND EVEN AS THE
AXIS OF DEEPER MOIST AXIS ASSOCIATED WITH THE AFOREMENTIONED
SHORTWAVE SHIFTS EAST ACROSS THE MOUNTAINS THIS MORNING...MOISTURE
NEAR -10C WILL BE VERY LIMITED. THUS...LIKELY POPS FOCUSED OVER THE
WESTERN HALF OF THE CWA WILL MAINLY BE FOR EVERY LIGHT RAIN/DRIZZLE
WITH ONLY A TRACE OR A FEW HUNDREDTHS OF QPF.
THIS LACK OF SIGNIFICANT PRECIP MAKES THE HIGH TEMP FORECAST MORE
CHALLENGING...AS THE WEDGE AIRMASS RESULTING FROM LIGHT PRECIP
FALLING INTO THE DRY SURFACE RIDGE SHOULD BE SHALLOW..ON
THE ORDER OF 1000FT. THE WARM ADVECTION ABOVE THE INVERSION SHOULD
INITIALLY HELP TO STRENGTHEN THE WEDGE AIRMASS...BUT FORECAST
SOUNDINGS DO SHOW SOME TOP-DOWN EROSION BEGINNING THIS
AFTERNOON....AND THE SOURCE OF DRY NORTHEASTERLY FLOW WILL BE LOST
AS THE PARENT HIGH SHIFTS OFF THE NEW ENGLAND COAST LATER TODAY.
THE CHALLENGING QUESTION IS HOW QUICKLY THE WEDGE FRONT WILL MIX
NORTH AND WEST ACROSS THE AREA. MODELS HAVE TRENDED SLIGHTLY MORE
AGGRESSIVE WITH THE MIXING...POSSIBLY DUE TO A BETTER HANDLE ON THE
MEAGER QPF EXPECTED THIS MORNING. WILL STILL SHOW A RANGE OF 50-86
FROM NORTHWEST TO SOUTHEAST...BUT THE STRONGEST TEMP GRADIENT THIS
AFTERNOON MAY LIE CLOSER TO THE TRIAD AND AREAS ALONG US HWY MAY BE
2-4 DEGREES WARMER THAN PREVIOUSLY FORECAST.
THE COVERAGE OF LIGHT RAIN WILL DECREASE LATE THIS AFTERNOON AND
SHOULD TRANSITION TO ONLY DRIZZLE OVER THE NORTHWEST PIEDMONT BY
00Z. DRYING ALOFT SHOULD ALLOW AREAS OF (DENSE)FOG TO FORM TONIGHT
WHERE WINDS ARE LIGHTEST...WITH THE HIGHEST SREF PROBABILITY WITHIN
THE REMNANT WEDGE AIRMASS. LOWS IN THE UPPER 40S TO MID 50S.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 310 AM FRIDAY...
SATURDAY/SATURDAY NIGHT...
IF THE LINGERING...SHALLOW WEDGE AIRMASS IS INDEED CONFINED TO ONLY
THE FAR NORTHWEST PIEDMONT BY SATURDAY MORNING...THEN MOST OF THE
CWA WILL HAVE LITTLE TROUBLE BREAKING OUT AS A STRONG DEEP LAYER
RIDGE BUILDS BACK ACROSS THE SOUTHEAST US. MODELS DO SHOW SOME
LINGERING MOISTURE IN THE 850-700MB LAYER...SO A FAIR AMOUNT IF
CLOUD COVER WILL KEEP HIGHS FROM REACHING THEIR FULL HEATING
POTENTIAL AS THICKNESSES SOAR WELL ABOVE 1380M. WILL ERR ON THE
SLIGHTLY COOLER SIDE OF STATISTICAL GUIDANCE..WHICH IS STILL SOLIDLY
IN THE LOW TO MID 70S ACROSS THE CWA. A COLD FRONT WILL BEGIN TO
APPROACH THE APPALACHIANS FROM THE WEST SATURDAY NIGHT. WITH A WEAK
PRESSURE GRADIENT EAST OF THE MOUNTAINS AND LINGERING LOW LEVEL
MOISTURE...STRATUS AND FOG MAY BE ISSUES ONCE AGAIN. LOWS WILL BE
UNSEASONABLY MILD IN THE 50S.
FOR SUNDAY/SUNDAY NIGHT: CONTINUED WARM AND GENERALLY DRY. THE
SURFACE AND MID LEVEL LONGWAVE RIDGE AXIS WILL BE ALIGNED JUST OFF
THE EAST COAST EARLY SUNDAY... WITH A MILD SOUTHWESTERLY SURFACE
FLOW AHEAD OF THE WAVY SURFACE COLD FRONT... EXPECTED TO STRETCH
ALONG THE WEST SLOPES OF THE APPALACHIANS. THE MID LEVEL FLOW FROM
THE SW REMAINS FAIRLY FLAT WITH ANY PERCEPTIBLE PERTURBATIONS
HOLDING WELL TO OUR NORTHWEST... AS SHOULD THE UPPER JET CORE AND
LOW LEVEL JET. WITH A LACK OF MECHANISMS TO FORCE ASCENT OVER
CENTRAL NC AND A FAIRLY LIGHT DIFFLUENT LOW LEVEL FLOW... MOST IF
NOT ALL PRECIP SHOULD HOLD NORTHWEST OF THE CWA THROUGH SUNDAY
NIGHT... AND INDEED THE MODEL CROSS SECTIONS REVEAL AN ANAFRONTAL
STRUCTURE WITH SLOPED ASCENT INTO THE COLD AIR OVER AND WEST OF THE
MOUNTAINS. SREF PROBABILITIES ALSO SHOW SINGLE-DIGIT CHANCES OF
MEASURABLE RAIN IN CENTRAL NC THROUGH SUNDAY NIGHT. LOW LEVEL
THICKNESSES REMAIN NEARLY 70 METERS ABOVE NORMAL... ALTHOUGH THIS
LAYER DOES ENCOMPASS A PORTION OF THE WARM NOSE ALOFT AND THUS
SOMEWHAT OVERREPRESENTS THE SURFACE WARMTH. THAT SAID... PREDICTED
925 MB TEMPS OF +15C TO +16C DO SUPPORT HIGHS INTO THE LOWER-MID
70S. FACTORING IN AT LEAST PARTLY CLOUDY SKIES WITH FLAT STRATOCU...
AND CONSIDERING THE MODEL DIFFERENCES WITH THE GFS CLOUDIER AND
COOLER IN THE WEST... EXPECT HIGHS TO RANGE FROM 71 NORTHWEST TO 76
IN THE EAST... LIKELY JUST SHY OF THE RECORD HIGHS. EXPECT AREAS OF
FOG AND LOW STRATUS SUNDAY NIGHT... AND THIS PLUS THE STEADY SW
BREEZE OVERNIGHT SHOULD KEEP TEMPS QUITE MILD OVERNIGHT... DROPPING
NO LOWER THAN 54-58... IN ACCORDANCE WITH LOCAL RESEARCH SHOWING
THAT STATISTICAL GUIDANCE LOWS IN PREFRONTAL WARM-ADVECTION
SCENARIOS ARE OFTEN TOO COOL. -GIH
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 255 AM FRIDAY...
A PATTERN CHANGE IS IN THE OFFING FOR NC THIS WEEK... AS THE RECENT
AND UPCOMING WARM PATTERN WILL BE SUPPLANTED BY AN INFLUX OF COLDER
CANADIAN-SOURCE AIR.
FOR MONDAY/MONDAY NIGHT: HEWING CLOSELY TO THE ECMWF SOLUTION...
WHICH AGREES FAIRLY WELL WITH BOTH THE EC AND GFS ENSEMBLE MEAN...
EXPECT ONE MORE MILD DAY. HOWEVER... THE STEADY SUCCESSION OF
WEAKENING WAVES TRACKING NE UP THE WEST SIDE OF THE RIDGE THROUGH
THE GREAT LAKES COMBINED WITH THE SSE DROP OF THE POLAR VORTEX FROM
NUNAVUT INTO HUDSON BAY WILL HELP SLIGHTLY TILT AND WEAKEN THE WRN
ATLANTIC RIDGE... SUCH THAT THE SURFACE FRONT WILL ALSO PIVOT MORE
SW-TO-NE AND INCH INTO WRN AND NW NC BY LATE MONDAY NIGHT... LEADING
TO IMPROVING RAIN CHANCES THERE. THE ECMWF HAS BEEN A BIT SLOWER AND
THUS DRIER THROUGH MONDAY NIGHT AS COMPARED TO THE GFS... HOWEVER
THE ECMWF HAS BEEN TRENDING A LITTLE FASTER AND ITS MOST RECENT RUN
BRINGS RAIN WELL INTO THE FORECAST AREA LATE AFTERNOON THROUGH THE
NIGHT. WILL CARRY A CHANCE OF SHOWERS... HIGHER OVER THE WRN AND NRN
FRINGE OF THE FORECAST AREA... FROM MIDDAY THROUGH MONDAY NIGHT.
HAVE TRIMMED HIGHS BACK A BIT IN THE NRN/WRN CWA... AND NOW HAVE
HIGHS OF 65-73. WITH EXPECTATIONS OF THE FRONT DIPPING SLIGHTLY PAST
THE NC/VA BORDER AS A BACKDOOR FRONT LATE MONDAY NIGHT AS THE ECMWF
SUGGESTS... WE SHOULD SEE LOWS RANGING FROM NEAR 50 IN THE NORTH TO
THE MID-UPPER 50S SOUTH OF HIGHWAY 64.
FOR TUESDAY/TUESDAY NIGHT: IT APPEARS INCREASINGLY LIKELY THAT THE
BACKDOOR FRONT WILL MAKE GOOD SOUTHWARD PROGRESS WELL INTO NC EARLY
TUESDAY... PROPELLED BY THE COOLER DENSE SURFACE HIGH OVER THE
CENTRAL CONUS AS WELL AS THE STRENGTHENING AND SOUTHWARD EXPANSION
OF THE POLAR VORTEX TO ENVELOP THE ST LAWRENCE VALLEY/GREAT LAKES/
NORTHEAST STATES BY EARLY WEDNESDAY. THE ECMWF TAKES A 25 KT SWRLY
LOW LEVEL JET UP ACROSS CENTRAL/ERN NC... ENHANCING MOIST UPGLIDE
AND SUBSEQUENTLY THE LIFT AND PRECIP OVER CENTRAL NC TUESDAY
AFTERNOON... IN CONJUNCTION WITH INCREASING HIGHER LEVEL LIFT IN THE
RIGHT ENTRANCE REGION OF A 150+ KT JET ACROSS THE NORTHEAST STATES.
WITHOUT GETTING TOO PRECISE IN THE DETAILS WHICH COULD STILL BE OFF
AT THIS TIME RANGE... WILL DEPICT AN INCREASE IN RAIN CHANCES ON
TUESDAY AS THE FRONT DROPS THROUGH. WE MAY IN FACT SEE TEMPS FALLING
DURING THE DAY ESPECIALLY IN THE NORTHERN HALF AS THE RAIN FALLS
INTO THE INCOMING CHILLY AIR MASS. HAVE CUT BACK HIGHS TO RANGE FROM
54 NORTH TO 68 SOUTHEAST... AND EVEN THIS COULD BE TOO WARM IN THE
NORTH. THOSE WITH PLANS ON TUESDAY SHOULD MONITOR OUR LATER
FORECASTS... AS THIS MAY END UP TURNING INTO QUITE A COOL/RAW/CLOUDY
AND POSSIBLY RAINY AFTERNOON. LOWS TUESDAY NIGHT 44-51 AS THE FRONT
DROPS TO OUR SOUTH AND COOLER AIR CONTINUES TO FILTER IN BENEATH
CONSIDERABLE CLOUD COVER.
FOR WEDNESDAY THROUGH THURSDAY: MODELS DIFFER IN THEIR HANDLING OF A
CLOSED LOW EXPECTED TO FORM OVER THE DESERT SOUTHWEST BY TUESDAY.
BOTH THE OPERATIONAL GFS AND ECMWF WEAKEN IT SLIGHTLY AND TAKE IT
EASTWARD INTO THE LOWER MISS VALLEY... WITH THE GFS MORE OF AN OPEN
WAVE AND ABOUT 12 HRS FASTER THAN THE ECMWF. THIS APPROACH WILL TEND
TO FLATTEN OUT THE INITIAL CYCLONIC MID LEVEL FLOW OVER THE MID
SOUTH AND MIDATLANTIC... ALLOWING THE FRONT TO NUDGE A BIT BACK
NORTHWARD TOWARD NC AND POTENTIALLY PROVIDING A FOCUS FOR LIFT ALONG
AND NORTH OF THE FRONT. BUT THERE ARE FAR TOO MANY QUESTION MARKS
REGARDING HOW MUCH MOISTURE WOULD BE AVAILABLE... EXACTLY WHERE THE
FRONT MIGHT END UP DURING THIS TIME FRAME... AND HOW MUCH (IF ANY)
THE POLAR STREAM WILL INFLUENCE THIS PATTERN... CRUCIAL CONSIDERING
THE GFS/ECMWF GREATLY DIVERGE WITH THEIR HANDLING OF THE POLAR
VORTEX. WILL KEEP TEMPS WITHIN A CATEGORY OF NORMAL FOR NOW... WITH
JUST SMALL CHANCE POPS UNTIL THE PICTURE BECOMES MORE CLEAR. -GIH
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 640 AM FRIDAY...
CURRENT TAF PERIOD...
ADVERSE AVIATION CONDITIONS HAVE DEVELOPED THIS MORNING AS PATCHY
LIGHT RAIN MOVES SOUTH TO NORTH ACROSS CENTRAL NC. CEILINGS VARY
FROM IFR OVER THE WESTERN PIEDMONT TO MVFR TOWARD KRWI AND
KFAY...WITH SOME POCKETS OF MVFR VSBYS IN THE HEAVIER RAIN/DRIZZLE.
AS THE PRECIP CONTINUES TO SPREAD NORTH AND EVENTUALLY NORTHEAST
THIS MORNING...CEILINGS AND VSBYS SHOULD REMAIN FAIRLY UNCHANGED
THROUGH MIDDAY...ALTHOUGH LIFR CEILINGS COULD STILL DEVELOP OVER THE
NORTHWEST PIEDMONT. THERE IS IS A CHANCE THAT SOUTHERLY LOW LEVEL
WINDS WILL BE ABLE TO MIX OUT SOME OF THE LOW CLOUDS NEAR KFAY AND
KRWI...LEADING TO MVFR CEILINGS DURING THE AFTERNOON.
HOWEVER...CONFIDENCE IN THIS HAPPENING IS ONLY MODERATE...WITH MUCH
LOWER CONFIDENCE TO THE WEST AT KRDU. LIGHT AND VARIABLE OR
NORTHEASTERLY WINDS CAN BE EXPECTED AT KGSO/KINT...WITH WINDS
SWITCHING TO SOUTHERLY THIS AFTERNOON AT KFAY AND KRWI.
SUB-VFR CEILINGS SHOULD PERSIST OVERNIGHT AND INTO MID-MORNING
SATURDAY. MEANWHILE...AS DRIER AIR ALOFT MOVES ACROSS THE AREA
TONIGHT...AREAS OF FOG ARE LIKELY TO DEVELOP...WITH DENSE FOG AND
POSSIBLE AFTER MIDNIGHT.
OUTLOOK...
WHILE CONDITIONS ARE EXPECTED TO IMPROVE BY MIDDAY SATURDAY...LOW
VSBYS AND CEILINGS WILL BE POSSIBLE AGAIN SATURDAY NIGHT. VFR
CONDITIONS WILL THEN REDEVELOP ON SUNDAY. THE NEXT CHANCE OF
WIDESPREAD SUB-VFR CONDITIONS WILL BE LATE MONDAY THROUGH TUESDAY AS
A COLD FRONT MOVES INTO THE AREA FROM THE WEST.
&&
.CLIMATE...
RECORD TEMPERATURE INFORMATION FOR JANUARY 12/13/14:
JAN 12TH RECORD HIGHS-
RDU: 76 (1890)
GSO: 76 (1907)
FAY: 77 (1916)
JAN 13TH RECORD HIGH MIN TEMPS-
RDU: 61 (2005)
GSO: 61 (1932)
FAY: 59 (2005)
JAN 13TH RECORD HIGHS-
RDU: 78 (2005)
GSO: 76 (1911)
FAY: 79 (2005)
JAN 14TH RECORD HIGH MIN TEMPS-
RDU: 61 (1995)
GSO: 59 (1995)
FAY: 62 (1972)
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...SMITH
SHORT TERM..SMITH/HARTFIELD
LONG TERM...HARTFIELD
AVIATION...SMITH
CLIMATE...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
315 AM EST FRI JAN 11 2013
.SYNOPSIS...
HIGH PRESSURE WILL EXTEND ACROSS THE REGION OVERNIGHT. A WARM FRONT
WILL LIFT NORTHWARD ACROSS CENTRAL NC THIS AFTERNOON AND TONIGHT.
HIGH PRESSURE ANCHORED OFF THE GEORGIA-NORTHEAST FLORIDA COAST WILL
BRING SPRING LIKE TEMPERATURES TO THE CAROLINAS THIS WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM FRIDAY...
WITHIN AN AMPLIFIED LONGWAVE PATTERN OVER THE CONUS...THE REMNANTS
OF THE UPPER THAT WAS OVER TX YESTERDAY IS NOW LIFTING NORTHEAST
ACROSS THE MID MS RIVER VALLEY REGION...WHILE A 1034MB SURFACE HIGH
OVER NEW ENGLAND EXTENDS SOUTH INTO THE CAROLINAS. STRENGTHENING
LOW LEVEL FLOW ON THE EASTERN FLANK OF THE LLJ OVER TN/KY IS LEADING
TO INCREASING WARM ADVECTION AND ISENTROPIC ACCENT ATOP THE SURFACE
RIDGE AXIS OVER CENTRAL NC THIS MORNING. THE SHALLOW LIFT WILL BE
MAXIMIZED THROUGH 15Z OVER THE WESTERN CWA...SHIFTING AND WEAKENING
TO THE NORTH AND EAST THIS AFTERNOON. MOST OF THE ECHOES CURRENTLY
SHOWING UP ARE NOW STARTING TO REACH THE GROUND...WITH MORE AND MORE
SITES REPORTING LIGHT RAIN OR DRIZZLE. BASED ON RAP SOUNDINGS...
MOISTURE IS MOSTLY FOCUSED BELOW THE FREEZING LEVEL AND EVEN AS THE
AXIS OF DEEPER MOIST AXIS ASSOCIATED WITH THE AFOREMENTIONED
SHORTWAVE SHIFTS EAST ACROSS THE MOUNTAINS THIS MORNING...MOISTURE
NEAR -10C WILL BE VERY LIMITED. THUS...LIKELY POPS FOCUSED OVER THE
WESTERN HALF OF THE CWA WILL MAINLY BE FOR EVERY LIGHT RAIN/DRIZZLE
WITH ONLY A TRACE OR A FEW HUNDREDTHS OF QPF.
THIS LACK OF SIGNIFICANT PRECIP MAKES THE HIGH TEMP FORECAST MORE
CHALLENGING...AS THE WEDGE AIRMASS RESULTING FROM LIGHT PRECIP
FALLING INTO THE DRY SURFACE RIDGE SHOULD BE SHALLOW..ON
THE ORDER OF 1000FT. THE WARM ADVECTION ABOVE THE INVERSION SHOULD
INITIALLY HELP TO STRENGTHEN THE WEDGE AIRMASS...BUT FORECAST
SOUNDINGS DO SHOW SOME TOP-DOWN EROSION BEGINNING THIS
AFTERNOON....AND THE SOURCE OF DRY NORTHEASTERLY FLOW WILL BE LOST
AS THE PARENT HIGH SHIFTS OFF THE NEW ENGLAND COAST LATER TODAY.
THE CHALLENGING QUESTION IS HOW QUICKLY THE WEDGE FRONT WILL MIX
NORTH AND WEST ACROSS THE AREA. MODELS HAVE TRENDED SLIGHTLY MORE
AGGRESSIVE WITH THE MIXING...POSSIBLY DUE TO A BETTER HANDLE ON THE
MEAGER QPF EXPECTED THIS MORNING. WILL STILL SHOW A RANGE OF 50-86
FROM NORTHWEST TO SOUTHEAST...BUT THE STRONGEST TEMP GRADIENT THIS
AFTERNOON MAY LIE CLOSER TO THE TRIAD AND AREAS ALONG US HWY MAY BE
2-4 DEGREES WARMER THAN PREVIOUSLY FORECAST.
THE COVERAGE OF LIGHT RAIN WILL DECREASE LATE THIS AFTERNOON AND
SHOULD TRANSITION TO ONLY DRIZZLE OVER THE NORTHWEST PIEDMONT BY
00Z. DRYING ALOFT SHOULD ALLOW AREAS OF (DENSE)FOG TO FORM TONIGHT
WHERE WINDS ARE LIGHTEST...WITH THE HIGHEST SREF PROBABILITY WITHIN
THE REMNANT WEDGE AIRMASS. LOWS IN THE UPPER 40S TO MID 50S.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 310 AM FRIDAY...
SATURDAY/SATURDAY NIGHT...
IF THE LINGERING...SHALLOW WEDGE AIRMASS IS INDEED CONFINED TO ONLY
THE FAR NORTHWEST PIEDMONT BY SATURDAY MORNING...THEN MOST OF THE
CWA WILL HAVE LITTLE TROUBLE BREAKING OUT AS A STRONG DEEP LAYER
RIDGE BUILDS BACK ACROSS THE SOUTHEAST US. MODELS DO SHOW SOME
LINGERING MOISTURE IN THE 850-700MB LAYER...SO A FAIR AMOUNT IF
CLOUD COVER WILL KEEP HIGHS FROM REACHING THEIR FULL HEATING
POTENTIAL AS THICKNESSES SOAR WELL ABOVE 1380M. WILL ERR ON THE
SLIGHTLY COOLER SIDE OF STATISTICAL GUIDANCE..WHICH IS STILL SOLIDLY
IN THE LOW TO MID 70S ACROSS THE CWA. A COLD FRONT WILL BEGIN TO
APPROACH THE APPALACHIANS FROM THE WEST SATURDAY NIGHT. WITH A WEAK
PRESSURE GRADIENT EAST OF THE MOUNTAINS AND LINGERING LOW LEVEL
MOISTURE...STRATUS AND FOG MAY BE ISSUES ONCE AGAIN. LOWS WILL BE
UNSEASONABLY MILD IN THE 50S.
FOR SUNDAY/SUNDAY NIGHT: CONTINUED WARM AND GENERALLY DRY. THE
SURFACE AND MID LEVEL LONGWAVE RIDGE AXIS WILL BE ALIGNED JUST OFF
THE EAST COAST EARLY SUNDAY... WITH A MILD SOUTHWESTERLY SURFACE
FLOW AHEAD OF THE WAVY SURFACE COLD FRONT... EXPECTED TO STRETCH
ALONG THE WEST SLOPES OF THE APPALACHIANS. THE MID LEVEL FLOW FROM
THE SW REMAINS FAIRLY FLAT WITH ANY PERCEPTIBLE PERTURBATIONS
HOLDING WELL TO OUR NORTHWEST... AS SHOULD THE UPPER JET CORE AND
LOW LEVEL JET. WITH A LACK OF MECHANISMS TO FORCE ASCENT OVER
CENTRAL NC AND A FAIRLY LIGHT DIFFLUENT LOW LEVEL FLOW... MOST IF
NOT ALL PRECIP SHOULD HOLD NORTHWEST OF THE CWA THROUGH SUNDAY
NIGHT... AND INDEED THE MODEL CROSS SECTIONS REVEAL AN ANAFRONTAL
STRUCTURE WITH SLOPED ASCENT INTO THE COLD AIR OVER AND WEST OF THE
MOUNTAINS. SREF PROBABILITIES ALSO SHOW SINGLE-DIGIT CHANCES OF
MEASURABLE RAIN IN CENTRAL NC THROUGH SUNDAY NIGHT. LOW LEVEL
THICKNESSES REMAIN NEARLY 70 METERS ABOVE NORMAL... ALTHOUGH THIS
LAYER DOES ENCOMPASS A PORTION OF THE WARM NOSE ALOFT AND THUS
SOMEWHAT OVERREPRESENTS THE SURFACE WARMTH. THAT SAID... PREDICTED
925 MB TEMPS OF +15C TO +16C DO SUPPORT HIGHS INTO THE LOWER-MID
70S. FACTORING IN AT LEAST PARTLY CLOUDY SKIES WITH FLAT STRATOCU...
AND CONSIDERING THE MODEL DIFFERENCES WITH THE GFS CLOUDIER AND
COOLER IN THE WEST... EXPECT HIGHS TO RANGE FROM 71 NORTHWEST TO 76
IN THE EAST... LIKELY JUST SHY OF THE RECORD HIGHS. EXPECT AREAS OF
FOG AND LOW STRATUS SUNDAY NIGHT... AND THIS PLUS THE STEADY SW
BREEZE OVERNIGHT SHOULD KEEP TEMPS QUITE MILD OVERNIGHT... DROPPING
NO LOWER THAN 54-58... IN ACCORDANCE WITH LOCAL RESEARCH SHOWING
THAT STATISTICAL GUIDANCE LOWS IN PREFRONTAL WARM-ADVECTION
SCENARIOS ARE OFTEN TOO COOL. -GIH
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 255 AM FRIDAY...
A PATTERN CHANGE IS IN THE OFFING FOR NC THIS WEEK... AS THE RECENT
AND UPCOMING WARM PATTERN WILL BE SUPPLANTED BY AN INFLUX OF COLDER
CANADIAN-SOURCE AIR.
FOR MONDAY/MONDAY NIGHT: HEWING CLOSELY TO THE ECMWF SOLUTION...
WHICH AGREES FAIRLY WELL WITH BOTH THE EC AND GFS ENSEMBLE MEAN...
EXPECT ONE MORE MILD DAY. HOWEVER... THE STEADY SUCCESSION OF
WEAKENING WAVES TRACKING NE UP THE WEST SIDE OF THE RIDGE THROUGH
THE GREAT LAKES COMBINED WITH THE SSE DROP OF THE POLAR VORTEX FROM
NUNAVUT INTO HUDSON BAY WILL HELP SLIGHTLY TILT AND WEAKEN THE WRN
ATLANTIC RIDGE... SUCH THAT THE SURFACE FRONT WILL ALSO PIVOT MORE
SW-TO-NE AND INCH INTO WRN AND NW NC BY LATE MONDAY NIGHT... LEADING
TO IMPROVING RAIN CHANCES THERE. THE ECMWF HAS BEEN A BIT SLOWER AND
THUS DRIER THROUGH MONDAY NIGHT AS COMPARED TO THE GFS... HOWEVER
THE ECMWF HAS BEEN TRENDING A LITTLE FASTER AND ITS MOST RECENT RUN
BRINGS RAIN WELL INTO THE FORECAST AREA LATE AFTERNOON THROUGH THE
NIGHT. WILL CARRY A CHANCE OF SHOWERS... HIGHER OVER THE WRN AND NRN
FRINGE OF THE FORECAST AREA... FROM MIDDAY THROUGH MONDAY NIGHT.
HAVE TRIMMED HIGHS BACK A BIT IN THE NRN/WRN CWA... AND NOW HAVE
HIGHS OF 65-73. WITH EXPECTATIONS OF THE FRONT DIPPING SLIGHTLY PAST
THE NC/VA BORDER AS A BACKDOOR FRONT LATE MONDAY NIGHT AS THE ECMWF
SUGGESTS... WE SHOULD SEE LOWS RANGING FROM NEAR 50 IN THE NORTH TO
THE MID-UPPER 50S SOUTH OF HIGHWAY 64.
FOR TUESDAY/TUESDAY NIGHT: IT APPEARS INCREASINGLY LIKELY THAT THE
BACKDOOR FRONT WILL MAKE GOOD SOUTHWARD PROGRESS WELL INTO NC EARLY
TUESDAY... PROPELLED BY THE COOLER DENSE SURFACE HIGH OVER THE
CENTRAL CONUS AS WELL AS THE STRENGTHENING AND SOUTHWARD EXPANSION
OF THE POLAR VORTEX TO ENVELOP THE ST LAWRENCE VALLEY/GREAT LAKES/
NORTHEAST STATES BY EARLY WEDNESDAY. THE ECMWF TAKES A 25 KT SWRLY
LOW LEVEL JET UP ACROSS CENTRAL/ERN NC... ENHANCING MOIST UPGLIDE
AND SUBSEQUENTLY THE LIFT AND PRECIP OVER CENTRAL NC TUESDAY
AFTERNOON... IN CONJUNCTION WITH INCREASING HIGHER LEVEL LIFT IN THE
RIGHT ENTRANCE REGION OF A 150+ KT JET ACROSS THE NORTHEAST STATES.
WITHOUT GETTING TOO PRECISE IN THE DETAILS WHICH COULD STILL BE OFF
AT THIS TIME RANGE... WILL DEPICT AN INCREASE IN RAIN CHANCES ON
TUESDAY AS THE FRONT DROPS THROUGH. WE MAY IN FACT SEE TEMPS FALLING
DURING THE DAY ESPECIALLY IN THE NORTHERN HALF AS THE RAIN FALLS
INTO THE INCOMING CHILLY AIR MASS. HAVE CUT BACK HIGHS TO RANGE FROM
54 NORTH TO 68 SOUTHEAST... AND EVEN THIS COULD BE TOO WARM IN THE
NORTH. THOSE WITH PLANS ON TUESDAY SHOULD MONITOR OUR LATER
FORECASTS... AS THIS MAY END UP TURNING INTO QUITE A COOL/RAW/CLOUDY
AND POSSIBLY RAINY AFTERNOON. LOWS TUESDAY NIGHT 44-51 AS THE FRONT
DROPS TO OUR SOUTH AND COOLER AIR CONTINUES TO FILTER IN BENEATH
CONSIDERABLE CLOUD COVER.
FOR WEDNESDAY THROUGH THURSDAY: MODELS DIFFER IN THEIR HANDLING OF A
CLOSED LOW EXPECTED TO FORM OVER THE DESERT SOUTHWEST BY TUESDAY.
BOTH THE OPERATIONAL GFS AND ECMWF WEAKEN IT SLIGHTLY AND TAKE IT
EASTWARD INTO THE LOWER MISS VALLEY... WITH THE GFS MORE OF AN OPEN
WAVE AND ABOUT 12 HRS FASTER THAN THE ECMWF. THIS APPROACH WILL TEND
TO FLATTEN OUT THE INITIAL CYCLONIC MID LEVEL FLOW OVER THE MID
SOUTH AND MIDATLANTIC... ALLOWING THE FRONT TO NUDGE A BIT BACK
NORTHWARD TOWARD NC AND POTENTIALLY PROVIDING A FOCUS FOR LIFT ALONG
AND NORTH OF THE FRONT. BUT THERE ARE FAR TOO MANY QUESTION MARKS
REGARDING HOW MUCH MOISTURE WOULD BE AVAILABLE... EXACTLY WHERE THE
FRONT MIGHT END UP DURING THIS TIME FRAME... AND HOW MUCH (IF ANY)
THE POLAR STREAM WILL INFLUENCE THIS PATTERN... CRUCIAL CONSIDERING
THE GFS/ECMWF GREATLY DIVERGE WITH THEIR HANDLING OF THE POLAR
VORTEX. WILL KEEP TEMPS WITHIN A CATEGORY OF NORMAL FOR NOW... WITH
JUST SMALL CHANCE POPS UNTIL THE PICTURE BECOMES MORE CLEAR. -GIH
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1240 AM FRIDAY...
CURRENT TAF PERIOD...
SOME MVFR CEILINGS ARE NOW BEING REPORTED ACROSS THE SOUTHERN
PORTIONS OF NC...MAINLY IMPACTING TERMINALS FROM KAFP TO KFAY/KCTZ.
LIGHT RAIN HAS SPREAD A LITTLE FURTHER NORTH AND IS APPROACHING
KINT/KGSO...WHERE CEILINGS SHOULD ALSO FALL TO MVFR LEVELS BY 09Z.
AS THE PRECIP CONTINUES TO SPREAD NORTH AND EVENTUALLY NORTHEAST
THIS MORNING...A COOL..MURKY WEDGE AIRMASS IS EXPECTED TO FORM OVER
MUCH OF CENTRAL NC...WITH CEILINGS FALLING TO IFR AND POSSIBLY EVEN
LIFR OVER THE NORTHWEST PIEDMONT. HOWEVER...DUE TO THE VERY LIGHT
NATURE OF THE RAIN...THERE IS IS A CHANCE THAT SOUTHERLY LOW LEVEL
WINDS WILL BE ABLE TO MIX OUT SOME OF THE LOW CLOUDS NEAR KFAY AND
KRWI...LEADING TO MVFR CEILINGS DURING THE AFTERNOON. CONFIDENCE IS
ONLY MODERATE AT THIS POINT AND WILL INCREASE ONCE IT IS MORE CLEAR
HOW STRONG OF A WEDGE AIRMASS DEVELOPS. WITHIN THE
WEDGE...PARTICULARLY AT KGSO AND KINT...LIGHT AND VARIABLE OR
NORTHEASTERLY WINDS CAN BE EXPECTED.
OUTLOOK...
CONDITIONS WILL LIKELY DETERIORATE TO IFR/LIFR IN LOW CEILINGS OR
FOG TONIGHT IN ASSOCIATION WITH A LINGERING COLD AIR DAMMING
WEDGE ACROSS THE AREA. IMPROVEMENT TO MVFR AND EVENTUALLY VFR IS
EXPECTED DURING THE DAY SATURDAY...EARLIEST AT FAY/RWI...FOLLOWED BY
RDU...WITH INT/GSO PERHAPS HANGING ON TO MVFR CEILINGS INTO PORTIONS
OF THE AFTERNOON. SATURDAY NIGHT...EXPECT A CHANCE FOR FOG AT ALL
TAF SITES. VFR CONDITIONS ARE EXPECTED TO PREVAIL ON SUNDAY AND
SUNDAY NIGHT. DETERIORATING CONDITIONS WILL BE POSSIBLE ONCE AGAIN
LATE MONDAY/MONDAY NIGHT.
&&
.CLIMATE...
RECORD TEMPERATURE INFORMATION FOR JANUARY 12/13/14:
JAN 12TH RECORD HIGHS-
RDU: 76 (1890)
GSO: 76 (1907)
FAY: 77 (1916)
JAN 13TH RECORD HIGH MIN TEMPS-
RDU: 61 (2005)
GSO: 61 (1932)
FAY: 59 (2005)
JAN 13TH RECORD HIGHS-
RDU: 78 (2005)
GSO: 76 (1911)
FAY: 79 (2005)
JAN 14TH RECORD HIGH MIN TEMPS-
RDU: 61 (1995)
GSO: 59 (1995)
FAY: 62 (1972)
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...SMITH
SHORT TERM..SMITH/HARTFIELD
LONG TERM...HARTFIELD
AVIATION...SMITH/BSD
CLIMATE...HARTFIELD
AREA FORECAST DISCUSSION
NWS MEDFORD OR
802 PM PST THU JAN 10 2013
.DISCUSSION...COLD...UNSTABLE...AND MOIST NORTHWESTERLY FLOW IS
MAINTAINING SNOW SHOWERS OVER THE WEST SIDE TONIGHT...WITH ONLY
THE LOWEST ELEVATIONS STILL GETTING RAIN AS THE SNOW LEVEL HAS
DECREASED TO AROUND 1000 FEET. A SHARP GRADIENT IN SNOW AMOUNTS
EXISTED TODAY...BASED ON ELEVATION. SNOW TOTALS WEST OF THE
CASCADES HAVE GENERALLY RANGED FROM JUST A TRACE BETWEEN 1000 AND
1500 FEET TO 4 INCHES AROUND 2000 FEET. TONIGHT...SNOW COULD
ACCUMULATE UP TO AN INCH DOWN TO 1000 FEET IN HEAVIER SNOW
SHOWERS...WHILE HIGHER ELEVATIONS COULD SEE A FEW MORE INCHES.
SHORTWAVE TROUGHS ARE MUCH LESS WELL-DEFINED TONIGHT THAN TODAY.
HOWEVER...THE RAP MODEL HAS A HANDLE ON THE NEXT IMPULSE...JUST
OFFSHORE NOW AND EVIDENT BY SOME CLOUD TOP COOLING. SO...ITS
LIKELY THAT SHOWERS WILL CONTINUE OVERNIGHT AS THIS SHORTWAVE
MOVES THROUGH...WITH ADDITIONAL IMPULSES MOVING THROUGH FRIDAY
MORNING. WINTER WEATHER ADVISORIES AT WSWMFR AND FROST/FREEZE
PRODUCTS AT THE COAST AT NPWMFR HAVE BEEN ISSUED. BY FRIDAY NIGHT
THE MODELS SUGGEST ANY SHORTWAVES SHOULD REMAIN OFFSHORE...DECREASING
THE CHANCE FOR SHOWERS FRIDAY NIGHT INTO SATURDAY. IT DOES LOOK
LIKE AFTERNOON WEATHER CONDITIONS FOR TRAVEL WILL IMPROVE
SIGNIFICANTLY SATURDAY AND SUNDAY COMPARED TO FRIDAY`S CONTINUED
SNOW SHOWERS.
EAST OF THE CASCADES...FRESH SNOW PACK AND SOME PARTIAL CLEARING
WILL HELP TEMPERATURES DROP TO SINGLE DIGITS OR NEAR ZERO
TONIGHT. HAVE UPDATED THE GRIDS TO REFLECT THIS IDEA.
PLEASE SEE THE PREVIOUS DISCUSSION FOR MORE DETAILS ON THE WEEKEND
WEATHER AND DRIER CONDITIONS EXPECTED NEXT WEEK.
&&
.AVIATION...ON THE WEST SIDE...COLD AND MOIST ONSHORE FLOW CONTINUES
TO BRING CUMULUS AND SHOWERS FROM THE WATERS IN OVER MUCH OF THE
WEST SIDE TONIGHT. CONDITIONS ARE GENERALLY MVFR, PRIMARILY DUE TO CIG,
OUTSIDE OF SHOWERS, BUT WILL BE OCCASIONALLY REDUCED TO IFR (BOTH
VIS AND CIG) IN SNOW SHOWERS. MOUNTAINS ARE OBSCURED FROM THE
CASCADE CREST WEST AND WILL REMAIN SO THROUGH THIS EVENING...WITH
ISOLATED MOUNTAIN OBSCURATION EAST OF THE CASCADES. CONDITIONS
ARE A MIX OF VFR...IFR...AND MVFR ON THE EAST SIDE AND CALIFORNIA
AS WELL WITH FEWER SNOW SHOWERS. CONDITIONS WILL IMPROVE SOME MOST
AREAS TONIGHT AS SHOWERS DECREASE. HOWEVER, SHOWERS WILL CONTINUE
TO OCCASIONALLY DROP CEILINGS AND VISIBILITY TO IFR THROUGH THE
NIGHT...ESPECIALLY IN UPSLOPE AREAS LIKE THE UMPQUA
DIVIDE...CASCADES...AND SISKIYOUS. AND AS ALWAYS IN A MOIST WINTER
ENVIRONMENT...FOG IN WEST SIDE VALLEYS IS ALWAYS POSSIBLE AS THE
NIGHT WEARS ON.
OCCASIONAL SHOWERS AND A MIX OF VFR AND MVFR CONDITIONS...WITH
ISOLATED AREAS OF IFR...WILL CONTINUE THROUGH FRIDAY MORNING.
MOUNTAIN OBSCURATION WILL CONTINUE TO AFFECT THE ENTIRE FORECAST AREA.
&&
.PREV DISCUSSION... /ISSUED 226 PM PST THU JAN 10 2013/
DISCUSSION...THE LATEST SATELLITE IMAGE SHOWS A SHORTWAVE MOVING
TOWARDS THE OREGON/CALIFORNIA BORDER. THIS FEATURE BROUGHT ENHANCED
SNOW SHOWERS FOR MOST OF THE WESTSIDE FROM ABOUT MID MORNING AND
AFTERNOON. SNOW SHOWERS WILL DECREASE SOME THIS EVENING...BUT
COLD AIR ALOFT REMAINS OVER THE REGION THROUGH FRIDAY WITH A MOIST
NORTH TO NORTHWEST FLOW. SO WE`LL CONTINUE TO HAVE SNOW SHOWERS MOVE
IN FROM THE NORTHWEST TONIGHT WITH MOST ACCUMULATIONS ABOVE 1500
FEET THIS EVENING...THEN 1000 FEET TONIGHT. BECAUSE OF THIS...HAVE
DECIDED TO EXTEND THE SNOW ADVISORIES FOR THE WESTSIDE INTO FRIDAY
MORNING. IN GENERAL...THE ROGUE VALLEY AND UMPQUA BASIN SHOULD GET
LESS THAN AN INCH TONIGHT. NORTHWEST FACING SLOPES OF THE
CASCADES AND SISKIYOUS WILL HAVE HIGHER SNOW ACCUMULATIONS...BUT
IT`S NOT EXPECTED TO BE ENOUGH TO WARRANT ANY WARNINGS OR
ADVISORIES.
SNOW SHOWERS CONTINUE INTO FRIDAY WITH SNOW LEVELS EXPECTED TO COME
UP TO AROUND 2000 FEET IN THE AFTERNOON AND FOR THE MOST PART
SHOWERS WILL BE LIGHT. SO THE CHANCE FOR ACCUMULATING SNOW WILL BE
LOW FRIDAY AFTERNOON. THE NAM AND GFS SHOW A BRIEF BREAK IN THE
WEATHER FRIDAY EVENING...THEN ANOTHER SHORTWAVE MOVES IN FROM THE
NORTH FRIDAY NIGHT. THE MODELS ARE IN SIMILAR AGREEMENT KEEPING MOST
OF THE PRECIPITATION CONFINED TO THE COAST AND MARINE WATERS WHICH
WILL LIMIT THE CONCERN FOR LOW ELEVATION SNOW FOR MOST INLAND
LOCATIONS.
MODELS DIFFER WITH THE NEXT SHORTWAVE SATURDAY...THE GFS CONTINUES
TO BE STRONGER FURTHER WEST....BUT HAS TREND WEAKER AND EAST OVER
THE PAST FEW MODEL RUNS. THE NAM IS WEAKER AND FARTHER EAST WHICH
WILL LIMIT THE AMOUNT OF PRECIPITATION...IF ANY AT ALL. THE EC IS
PRACTICALLY NON-EXISTENT. GIVEN THE GFS HAS TRENDED WEAKER WITH
THIS...TEND TO THINK THE WEATHER AND DRIER SOLUTION IS THE WAY TO
GO. SO HAVE TRENDED POPS AND QPF AMOUNTS DOWN. -PETRUCELLI
EXTENDED...(SUNDAY THROUGH WEDNESDAY)...NORTHERLY FLOW ALOFT
CONTINUES ON SUNDAY, BUT IS BECOMING MORE ANTICYCLONIC AS AN UPPER
LEVEL RIDGE OF HIGH PRESSURE BUILDS TOWARD THE COAST. THIS WILL
RESULT IN DRYING OF THE ATMOSPHERE ALONG WITH DECREASING CHANCES FOR
PRECIPITATION. THE MODELS REMAIN IN GOOD AGREEMENT THAT THE RIDGE
WILL GRADUALLY BUILD OVER THE NORTHEAST PACIFIC AND INTO THE PACIFIC
NORTHWEST FOR THE REMAINDER OF THE PERIOD. THIS WILL RESULT IN DRY
WEATHER THROUGH AT LEAST WEDNESDAY WITH OFF SHORE FLOW IN THE LOW
LEVELS. DESPITE THE OFFSHORE FLOW, THE LOW LEVEL INVERSION WILL BE
PRESENT AND WILL LIKELY LEAD TO LATE NIGHT AND MORNING VALLEY FOG,
AT LEAST ON THE WEST SIDE. -WRIGHT
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...FROST ADVISORY FROM 2 AM TO 8 AM PST FRIDAY FOR ORZ021-022.
WINTER WEATHER ADVISORY UNTIL 10 AM PST FRIDAY ABOVE 1000 FEET
FOR FOR ORZ021-022.
FREEZE WARNING FROM 2 AM TO 8 AM PST FRIDAY FOR ORZ021-022.
WINTER WEATHER ADVISORY UNTIL 10 AM PST FRIDAY ABOVE 1000 FEET
FOR FOR ORZ023.
WINTER WEATHER ADVISORY UNTIL 10 AM PST FRIDAY FOR ORZ025.
WINTER WEATHER ADVISORY UNTIL 10 AM PST FRIDAY FOR ORZ024-026.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS UNTIL 7 AM PST FRIDAY FOR
PZZ350-356.
HAZARDOUS SEAS WARNING UNTIL 4 AM PST FRIDAY FOR PZZ350-356.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 7 AM PST FRIDAY FOR
PZZ370-376.
HAZARDOUS SEAS WARNING UNTIL 4 AM PST FRIDAY FOR PZZ370-376.
$$
NSK/TRW/NSK
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
404 PM EST FRI JAN 11 2013
.SYNOPSIS...
AN UPPER LEVEL RIDGE WILL REMAIN OVER THE EASTERN PART OF THE
COUNTRY INTO THE WEEKEND. A SERIES OF WEAKENING DISTURBANCES WILL
MOVE THROUGH THIS UPPER RIDGE...BRINGING OCCASIONAL BOUTS OF
MAINLY LIGHT PRECIPITATION ALONG WITH UNSEASONABLE WARMTH. THE
WEATHER WILL REMAIN UNSETTLED THROUGH MIDWEEK...WHEN MUCH COLDER
AIR WILL MOVE IN FROM THE GREAT LAKES.
&&
.NEAR TERM /UNTIL 11 PM THIS EVENING/...
SHORT WAVE TROUGH EVIDENT ON WV IMAGERY OVER LAKE ERIE/NERN OH
AND RIGHT ON TIME. MAIN SLUG OF PRECIP SEEMS TO BE UPON THE REGION
AT 19Z...WITH GENERALLY LIGHT AND SPOTTY SHRA BEHIND THAT. THE
BACK EDGE OF THE PRECIP IS RIGHT ALONG WITH THE BASE OF THE
TROUGH AND EXTRAPOLATION MOVES MOST OF THE PRECIP TO THE EAST OF
THE ENTIRE AREA BY 00Z. TEMPS SHOULD HOLD RELATIVELY STEADY INTO
THE EVENING AS THE RAIN AND CLOUDS DOMINATE. THEY COULD WARM UP
5-6F IN THE WEST DURING THE EVENING AS WINDS TURN MORE SWRLY.
&&
.SHORT TERM /11 PM THIS EVENING THROUGH 6 PM SATURDAY/...
WAVE TO THE EAST BEFORE THE PERIOD STARTS...SO ONLY THE LOW CLOUDS
WILL BE LEFT OVER. THESE CLOUDS ARE THE FORECAST PROBLEM FOR THE
PERIOD. CLOUDS A DRIZZLE OVER MOST OF THE AREA OVERNIGHT WILL KEEP
IT VERY MILD...WITH OVERNIGHT MINS 15-25F ABOVE NORMALS...AND EVEN
5-10F ABOVE NORMAL MAXES. IF IT WAS NOT FOR THE LOW CLOUDS WE
WOULD EASILY REACH RECORD MAXES SAT. BUT THE TREND IN THE MODEL
PROGS THESE LAST 36+ HRS IS TO LINGER THE CLOUDS WELL INTO THE
DAY IN THE CENTRAL AND EASTERN ZONES. SFC HIGH WILL BE RIGHT OVER
THE LOCAL AREA LEADING TO LIGHT WINDS. SO SOME LOCATIONS IN THE
EAST MAY NEVER GET OUT OF THE SOUP. HAVE THEREFORE KEPT MAXES IN
THE M40S AROUND IPT AND IN THE L-M50S FOR A GREAT PORTION OF THE
AREA. U50S STILL POSSIBLE IN THE SOUTH. WHILE IT MAY SEEM LIKE
IPT/VCTY WILL BE MISSING OUT ON WARMTH...IT SHOULD STILL BE 15F
ABOVE NORMAL MAXES - WHICH IS ABNORMALLY WARM FOR ANY POINT IN THE
YEAR. IT IS JUST JANUARY - AND THE NEXT TWO WEEKS ARE THE COLDEST
PERIOD OF THE YEAR CLIMATOLOGICALLY SPEAKING. OTHER THAN A LITTLE
DRIZZLE OUT OF THE LOWEST CLOUDS ON SAT AM...NO OTHER PRECIP IS
FORESEEN. SFC RIDGE AXIS DOES MOVE SLIGHTLY TO THE EAST OF THE
AREA BY SAT EVENING.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
MILD WEATHER FOR THE WEEKEND AND EARLY NEXT WEEK WILL GIVE WAY TO
COOL DOWN FOR LATE WEEK.
AN UPPER RIDGE OVER THE REGION SAT WILL SLOWLY SLIDE EAST BY
SUNDAY...ALLOWING A WEAK WARM FRONT TO SLIP THROUGH SAT NIGHT -
ACCOMPANIED BY A CHANCE FOR SHOWERS. BETTER RAIN CHANCES WILL
REMAIN OFF TO OUR WEST ALONG A COLD FRONT SLOWLY INCHING EASTWARD
TOWARD THE REGION. THIS WILL ALLOW VERY MILD AIR TO REMAIN IN
PLACE THROUGH THE WEEKEND...WITH HIGHS IN MOST PLACES REACHING THE
50S...AND POSS 60F ACOSS SOUTHERN TIER.
MODELS ALL HAVE PRETTY GOOD TIMING AGREEMENT ON THE THIS INITIAL
FRONTAL BOUNDARY AND SOME WEAK SHORTWAVES RIDING ALONG IT. HIGHEST
POPS INTO SUNDAY REMAIN IN WESTERN AREAS NEAREST THE
BOUNDARY...WHERE IT SHOULD REMAIN INTERMITTANTLY SHOWERY. FRONT
PUSHES THROUGH SUN NIGHT INTO MON...WITH MORE WIDESPREAD
PRECIPITATION. QPF TOTALS THROUGH THAT 36-48H PERIOD LOOK TO BE
AROUND 1.0-1.5 INCHES IN NW MTNS...TAPERING TO AROUND 0.5 IN THE
SE. WITH A SNOWPACK /WATER EQUIV AROUND AN INCH/ PERSISTING IN THE
NORTHERN MOUNTAINS...THERE WILL BE AT LEAST A SMALL POTENTIAL FOR
SCT MINOR FLOODING ISSUES. BUT LOOKS LIKE PRECIP WILL BE SPREAD
OUT ENOUGH IN TIME AND NOT HEAVY ENOUGH TO CAUSE WIDESPREAD
ISSUES...THOUGH RIVERS AND STREAMS ACROSS CENTRAL PA WILL SEE
NOTICABLE RISES THIS WEEKEND.
AS FRONTAL BOUNDARY SLOWS FURTHER JUST TO OUR SOUTHEAST MON INTO
TUE...OPERATIONAL MODELS SUGGEST THE POTENTIAL FOR AT LEAST ONE
ADDITIONAL WAVE TO RIPPLE UP THAT FRONT. WITH THE COLD AIR
BEGINNING TO OOZE IN FROM THE NW BRINGING 850MB TEMPS BACK BELOW
0C...THE NORTHERN EDGE OF THE PRECIP RUNS THE RISK OF BEING
SNOW...AS WOULD BE EXPECTED IN MOST NORMAL JANUARYS. AMOUNTS
SHOULD BE LIGHT...BUT CONTINUED THE RAIN/SNOW MIX IN WX GRIDS WITH
DIMINISHING POPS.
MODEL DIFFERENCES ARISE BY MIDWEEK CONCERNING ARRIVAL OF COLDER
AIR...BUT TREND WILL MOST DEFINITELY BE COLDER. GFS BRINGS A
POTENT SURGE OF ARCTIC AIR OUR WAY FOR LATER WED INTO THU...WHILE
THE ECMWF/ECENS ARE SLOWER...AND CLOSER TO THE END OF THE WEEK.
THE GFS/GEFS ALSO SHOW A MORE SIGNIFICANT EVENTUAL SOUTHWARD
PLUNGE OF THE COLD AIR INTO THE EASTERN US WHILE THE ECMWF/ECENS
SUGGEST MORE OF A GLANCING BLOW WITH THE BEST COLD CONFINED TO THE
NERN US...ESPECIALLY NEW ENGLAND/NY.
BROAD NW FLOW BRINGS SCT SNOW SHOWERS BACK TO NW MTNS LATE WEEK AS
TEMPS COOL BACK TOWARD NORMALS.
&&
.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
WINDOW OF STRONGER WINDS IS SHRINKING AND ONLY A BRIEF PERIOD
EXISTS FOR GOOD MIXING OVER THE AREA. WILL THEREFORE KEEP WIND
SPEEDS LOWER THAN 10 KTS FOR MOST TERMINALS...AND LEAVE THEM ONLY
SLIGHTLY GUSTY IN THE WEST FOR 2-3 MORE HRS. LLWS STILL A CONCERN
INTO THE EARLY EVENING - UNTIL THE SHORT WAVE IS PAST US.
MULTIPLE BANDS OF SHOWERS HAVE CONGEALED INTO ONE MAJOR BAND/AREA
AND A WIDE AREA OF SCT/NMRS SHRA TO THE WEST. THE RETURNS ARE
MOVING STEADILY AND TIMING SUPPORTED BY LATEST HRRR SHUNTS MOST
OF THE RAIN TO THE EAST OF THE AREA BY 02Z. ALMOST NO RISK FOR
THUNDER NOW...SO NO MENTION PLACED INTO THE TAFS. RESIDUAL LOW LVL
MOISTURE AND A NEARLY CALM WIND AND A BIT OF COOLING WILL LIKELY
LEAD TO WIDESPREAD LOW CLOUDS/FOG OVERNIGHT. LATEST SREF/NAM AND GFS
FCSTS ALL SUPPORT THIS SCENARIO...INDICATING WIDESPREAD IFR CONDS
LIKELY. GFS MOS IS MUCH MORE OPTIMISTIC...BUT PREPONDERANCE OF
EVIDENCE POINTS TO LOW CLOUDS AND EVEN DRIZZLE PERSISTING INTO SAT
MORNING. THICK LOW CLOUDS LINGER FOR THE MORNING HOURS ON
SAT...AND MOST IF NOT ALL OF THE DAY IN THE EAST. A SFC LOW PASSES
WELL TO THE NORTH ON SUNDAY AND THE COLD FRONT ASSOCD WITH IT GOES
THRU VERY SLOWLY. AT LEAST ONE MORE WAVE OF LOW PRESSURE RIDES UP
FROM THE S ON MONDAY...GIVING LITTLE BREAK FROM A MONOTONOUS
MVFR/IFR FORECAST IN RAIN AND LOW CLOUDS/FOG.
OUTLOOK...
SUN...VFR SE...MVFR/IFR IN SHRA/CIGS NW.
MON...MVFR IN WIDESPREAD SH/RA.
MON NITE...CFROPA...NW/UPSLOPE FLOW SHSN.
TUE-WED...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO/LA CORTE
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...RXR
AVIATION...DANGELO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
240 PM EST FRI JAN 11 2013
.SYNOPSIS...
AN UPPER LEVEL RIDGE WILL REMAIN OVER THE EASTERN PART OF THE
COUNTRY INTO THE WEEKEND. A SERIES OF WEAKENING DISTURBANCES WILL
MOVE THROUGH THIS UPPER RIDGE...BRINGING OCCASIONAL BOUTS OF
MAINLY LIGHT PRECIPITATION ALONG WITH UNSEASONABLE WARMTH. THE
WEATHER WILL REMAIN UNSETTLED THROUGH MIDWEEK...WHEN MUCH COLDER
AIR WILL MOVE IN FROM THE GREAT LAKES.
&&
.NEAR TERM /UNTIL 11 PM THIS EVENING/...
SHORT WAVE TROUGH EVIDENT ON WV IMAGERY OVER LAKE ERIE/NERN OH
AND RIGHT ON TIME. MAIN SLUG OF PRECIP SEEMS TO BE UPON THE REGION
AT 19Z...WITH GENERALLY LIGHT AND SPOTTY SHRA BEHIND THAT. THE
BACK EDGE OF THE PRECIP IS RIGHT ALONG WITH THE BASE OF THE
TROUGH AND EXTRAPOLATION MOVES MOST OF THE PRECIP TO THE EAST OF
THE ENTIRE AREA BY 00Z. TEMPS SHOULD HOLD RELATIVELY STEADY INTO
THE EVENING AS THE RAIN AND CLOUDS DOMINATE. THEY COULD WARM UP
5-6F IN THE WEST DURING THE EVENING AS WINDS TURN MORE SWRLY.
&&
.SHORT TERM /11 PM THIS EVENING THROUGH 6 PM SATURDAY/...
WAVE TO THE EAST BEFORE THE PERIOD STARTS...SO ONLY THE LOW CLOUDS
WILL BE LEFT OVER. THESE CLOUDS ARE THE FORECAST PROBLEM FOR THE
PERIOD. CLOUDS A DRIZZLE OVER MOST OF THE AREA OVERNIGHT WILL KEEP
IT VERY MILD...WITH OVERNIGHT MINS 15-25F ABOVE NORMALS...AND EVEN
5-10F ABOVE NORMAL MAXES. IF IT WAS NOT FOR THE LOW CLOUDS WE
WOULD EASILY REACH RECORD MAXES SAT. BUT THE TREND IN THE MODEL
PROGS THESE LAST 36+ HRS IS TO LINGER THE CLOUDS WELL INTO THE
DAY IN THE CENTRAL AND EASTERN ZONES. SFC HIGH WILL BE RIGHT OVER
THE LOCAL AREA LEADING TO LIGHT WINDS. SO SOME LOCATIONS IN THE
EAST MAY NEVER GET OUT OF THE SOUP. HAVE THEREFORE KEPT MAXES IN
THE M40S AROUND IPT AND IN THE L-M50S FOR A GREAT PORTION OF THE
AREA. U50S STILL POSSIBLE IN THE SOUTH. WHILE IT MAY SEEM LIKE
IPT/VCTY WILL BE MISSING OUT ON WARMTH...IT SHOULD STILL BE 15F
ABOVE NORMAL MAXES - WHICH IS ABNORMALLY WARM FOR ANY POINT IN THE
YEAR. IT IS JUST JANUARY - AND THE NEXT TWO WEEKS ARE THE COLDEST
PERIOD OF THE YEAR CLIMATOLOGICALLY SPEAKING. OTHER THAN A LITTLE
DRIZZLE OUT OF THE LOWEST CLOUDS ON SAT AM...NO OTHER PRECIP IS
FORESEEN. SFC RIDGE AXIS DOES MOVE SLIGHTLY TO THE EAST OF THE
AREA BY SAT EVENING.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
WE ARE IN FOR A MILD START TO THE EXTENDED PART OF THE FORECAST.
THE UPPER RIDGE MAINTAINS ITSELF INTO THE WEEKEND...WHICH RESULTS
IN THE APPROACHING COLD FRONT SLOWING DOWN AND BECOMING WAVY AS
IT INCHES EAST. THIS KEEPS US IN THE MILD AIR THROUGH AT LEAST
SUNDAY BEFORE THE COLD FRONT FINALLY REINTRODUCES THE COLD AIR
STARTING ON MONDAY.
MODELS ALL HAVE PRETTY GOOD TIMING AGREEMENT ON THE THIS INITIAL
FRONTAL BOUNDARY...BUT AS USUAL...DIFFERENCES ARISE AS WE GO OUT
IN TIME. THE GFS BRINGS A POTENT SURGE OF ARCTIC AIR OUR WAY FOR
LATER WED INTO THU...WHILE THE ECMWF/ECENS ARE SLOWER...AND CLOSER
TO THE END OF THE WEEK. THE GFS/GEFS ALSO SHOW A MORE SIGNIFICANT
EVENTUAL SOUTHWARD PLUNGE OF THE COLD AIR INTO THE EASTERN US
WHILE THE ECMWF/ECENS SUGGEST MORE OF A GLANCING BLOW WITH THE
BEST COLD CONFINED TO THE NERN US...ESPECIALLY NEW ENGLAND/NY.
SENSIBLE WEATHER WILL BE GOVERNED BY THE FRONT THAT WILL ONLY
SLOWLY MOVE OFF TO OUR SE AS IT STRUGGLES AGAINST THE BROAD SW
FLOW ALOFT IN THE STRONG UPPER RIDGE THAT WILL BE STUBBORN TO
RETREAT OFF THE SERN US. OPERATIONAL MODELS SUGGEST THE POTENTIAL
FOR AT LEAST ONE ADDITIONAL WAVE TO RIPPLE UP THAT FRONT FOR SOME
TIME LATER MONDAY INTO TUESDAY. WITH THE COLD AIR GETTING
CLOSER...THE NORTHERN EDGE OF THE PRECIP RUNS THE RISK OF BEING
SNOW...AS WOULD BE EXPECTED IN MOST NORMAL JANUARYS. IT IS TOO
FAR OUT TO GET FANCY SO THE FORECAST HAS RAIN OR SNOW AT THIS
RANGE...AND HOLDS OFF THE COLDEST AIR UNTIL LATE WEEK.
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
WINDOW OF STRONGER WINDS IS SHRINKING AND ONLY A BRIEF PERIOD
EXISTS FOR GOOD MIXING OVER THE AREA. WILL THEREFORE KEEP WIND
SPEEDS LOWER THAN 10 KTS FOR MOST TERMINALS...AND LEAVE THEM ONLY
SLIGHTLY GUSTY IN THE WEST FOR 2-3 MORE HRS. LLWS STILL A CONCERN
INTO THE EARLY EVENING - UNTIL THE SHORT WAVE IS PAST US.
MULTIPLE BANDS OF SHOWERS HAVE CONGEALED INTO ONE MAJOR BAND/AREA
AND A WIDE AREA OF SCT/NMRS SHRA TO THE WEST. THE RETURNS ARE
MOVING STEADILY AND TIMING SUPPORTED BY LATEST HRRR SHUNTS MOST
OF THE RAIN TO THE EAST OF THE AREA BY 02Z. ALMOST NO RISK FOR
THUNDER NOW...SO NO MENTION PLACED INTO THE TAFS. RESIDUAL LOW LVL
MOISTURE AND A NEARLY CALM WIND AND A BIT OF COOLING WILL LIKELY
LEAD TO WIDESPREAD LOW CLOUDS/FOG OVERNIGHT. LATEST SREF/NAM AND GFS
FCSTS ALL SUPPORT THIS SCENARIO...INDICATING WIDESPREAD IFR CONDS
LIKELY. GFS MOS IS MUCH MORE OPTIMISTIC...BUT PREPONDERANCE OF
EVIDENCE POINTS TO LOW CLOUDS AND EVEN DRIZZLE PERSISTING INTO SAT
MORNING. THICK LOW CLOUDS LINGER FOR THE MORNING HOURS ON
SAT...AND MOST IF NOT ALL OF THE DAY IN THE EAST. A SFC LOW PASSES
WELL TO THE NORTH ON SUNDAY AND THE COLD FRONT ASSOCD WITH IT GOES
THRU VERY SLOWLY. AT LEAST ONE MORE WAVE OF LOW PRESSURE RIDES UP
FROM THE S ON MONDAY...GIVING LITTLE BREAK FROM A MONOTONOUS
MVFR/IFR FORECAST IN RAIN AND LOW CLOUDS/FOG.
OUTLOOK...
SUN...VFR SE...MVFR/IFR IN SHRA/CIGS NW.
MON...MVFR IN WIDESPREAD SH/RA.
MON NITE...CFROPA...NW/UPSLOPE FLOW SHSN.
TUE-WED...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO/LA CORTE
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...LA CORTE
AVIATION...DANGELO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
102 PM EST FRI JAN 11 2013
.SYNOPSIS...
AN UPPER LEVEL RIDGE WILL REMAIN OVER THE EASTERN PART OF THE
COUNTRY INTO THE WEEKEND. A SERIES OF WEAKENING DISTURBANCES WILL
MOVE THROUGH THIS UPPER RIDGE...BRINGING OCCASIONAL BOUTS OF
MAINLY LIGHT PRECIPITATION ALONG WITH UNSEASONABLE WARMTH. THE
WEATHER WILL REMAIN UNSETTLED THROUGH MIDWEEK...WHEN MUCH COLDER
AIR WILL MOVE IN FROM THE GREAT LAKES.
&&
.NEAR TERM /UNTIL 11 PM THIS EVENING/...
FCST WELL ON TRACK WITH THE MAJOR SHORT WAVE TROUGH SLATED TO PUSH
THROUGH PA BY 03Z. THE MAIN FORCING WILL BE ABOUT 3-4 HRS
AHEAD...AND HIGH POPS ALL AROUND. MAIN SLUG OF PRECIP SEEMS TO BE
UPON THE WRN HALF OF THE AREA...WITH GENERALLY LIGHT AND SPOTTY
SHRA BEHIND THAT. THE BACK EDGE OF THE PRECIP AND MOST LIKELY THE
BASE OF THE TROUGH IS ALREADY INTO EASTERN OHIO. SOME LIMITED
ELEVATED INSTABILITY IS POSSIBLE OVER THE WESTERN/CENTRAL MTS
LATE THIS AFTN/EARLY EVENING...WITH JUST A MENTION NEEDED AND IN
THERE ALREADY. TEMPS SHOULD HOLD RELATIVELY STEADY INTO THE
EVENING AS THE RAIN AND CLOUDS DOMINATE.
&&
.SHORT TERM /11 PM THIS EVENING THROUGH 6 PM SATURDAY/...
THE UPPER SHORTWAVE WILL SCOOT QUICKLY THROUGH THE RIDGE...WITH
RISING HEIGHTS ALOFT RETURNING BY EVENING. KEPT THE BEST CHANCE
FOR LINGERING SHOWERS EARLY IN THE PERIOD IN THE EAST...WITH
DRYING SETTING IN OVERNIGHT. I DID NOT GO FOR A LOT OF FOG WHICH
WOULD NORMALLY SEEM TO BE THE WAY TO GO WITH RAIN ENDING AND HIGH
PRESSURE QUICKLY BUILDING IN OVERNIGHT...BUT AT THIS POINT I
EXPECT A LOT OF RESIDUAL CLOUDINESS SHUD THWART SIG RADIATIONAL
COOLING AND FOG FORMATION. WILL HAVE HIGH CLOUDS PAINTED THRU THE
PERIOD...WHICH WILL LIMIT THE TEMP RISE EARLY ON SAT. IF IT WAS
NOT FOR THE LOW CLOUDS WE WOULD EASILY REACH RECORD MAXES SAT.
BUT THE CLOUDS NOW LOOK TO LINGER WELL INTO THE DAY IN THE CENTRAL
AND EASTERN ZONES. HAVE THEREFORE KEPT MAXES IN THE U40S AT IPT
AND L50S FOR A GREAT PORTION OF THE AREA. U50S STILL
POSSIBLE...BUT THAT MAY BE A BIT AMBITIOUS WITH CURRENT CLOUD
OUTLOOK.
WITH THE APPROACHING FRONT PRETTY MUCH WASHING AS IT MOVES OUR
WAY...WE WILL REMAIN ESSENTIALLY IN THE WARM SECTOR OF THE
STRONGER LOW STILL WAY OUT TO OUR WEST...THUS A MILD NIGHT IS IN
STORE WITH READINGS PROBABLY STAYING ABOVE FREEZING
EVERYWHERE...QUITE UNUSUAL FOR MID JANUARY...THE CLIMATALOGICALLY
COLDEST TIME OF THE YEAR.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
WE ARE IN FOR A MILD START TO THE EXTENDED PART OF THE FORECAST.
THE UPPER RIDGE MAINTAINS ITSELF INTO THE WEEKEND...WHICH RESULTS
IN THE APPROACHING COLD FRONT SLOWING DOWN AND BECOMING WAVY AS
IT INCHES EAST. THIS KEEPS US IN THE MILD AIR THROUGH AT LEAST
SUNDAY BEFORE THE COLD FRONT FINALLY REINTRODUCES THE COLD AIR
STARTING ON MONDAY.
MODELS ALL HAVE PRETTY GOOD TIMING AGREEMENT ON THE THIS INITIAL
FRONTAL BOUNDARY...BUT AS USUAL...DIFFERENCES ARISE AS WE GO OUT
IN TIME. THE GFS BRINGS A POTENT SURGE OF ARCTIC AIR OUR WAY FOR
LATER WED INTO THU...WHILE THE ECMWF/ECENS ARE SLOWER...AND CLOSER
TO THE END OF THE WEEK. THE GFS/GEFS ALSO SHOW A MORE SIGNIFICANT
EVENTUAL SOUTHWARD PLUNGE OF THE COLD AIR INTO THE EASTERN US
WHILE THE ECMWF/ECENS SUGGEST MORE OF A GLANCING BLOW WITH THE
BEST COLD CONFINED TO THE NERN US...ESPECIALLY NEW ENGLAND/NY.
SENSIBLE WEATHER WILL BE GOVERNED BY THE FRONT THAT WILL ONLY
SLOWLY MOVE OFF TO OUR SE AS IT STRUGGLES AGAINST THE BROAD SW
FLOW ALOFT IN THE STRONG UPPER RIDGE THAT WILL BE STUBBORN TO
RETREAT OFF THE SERN US. OPERATIONAL MODELS SUGGEST THE POTENTIAL
FOR AT LEAST ONE ADDITIONAL WAVE TO RIPPLE UP THAT FRONT FOR SOME
TIME LATER MONDAY INTO TUESDAY. WITH THE COLD AIR GETTING
CLOSER...THE NORTHERN EDGE OF THE PRECIP RUNS THE RISK OF BEING
SNOW...AS WOULD BE EXPECTED IN MOST NORMAL JANUARYS. IT IS TOO
FAR OUT TO GET FANCY SO THE FORECAST HAS RAIN OR SNOW AT THIS
RANGE...AND HOLDS OFF THE COLDEST AIR UNTIL LATE WEEK.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
WINDOW OF STRONGER WINDS IS SHRINKING AND ONLY A BRIEF PERIOD
EXISTS FOR GOOD MIXING OVER THE AREA. WILL THEREFORE KEEP WIND
SPEEDS LOWER THAN 10 KTS FOR MOST TERMINALS...AND LEAVE THEM ONLY
SLIGHTLY GUSTY IN THE WEST FOR 2-3 MORE HRS. LLWS STILL A CONCERN
INTO THE EARLY EVENING - UNTIL THE SHORT WAVE IS PAST US.
MULTIPLE BANDS OF SHOWERS HAVE CONGEALED INTO ONE MAJOR BAND/AREA
AND A WIDE AREA OF SCT/NMRS SHRA TO THE WEST. THE RETURNS ARE
MOVING STEADILY AND TIMING SUPPORTED BY LATEST HRRR SHUNTS MOST
OF THE RAIN TO THE EAST OF THE AREA BY 02Z. ALMOST NO RISK FOR
THUNDER NOW...SO NO MENTION PLACED INTO THE TAFS. RESIDUAL LOW LVL
MOISTURE AND A NEARLY CALM WIND AND A BIT OF COOLING WILL LIKELY
LEAD TO WIDESPREAD LOW CLOUDS/FOG OVERNIGHT. LATEST SREF/NAM AND GFS
FCSTS ALL SUPPORT THIS SCENARIO...INDICATING WIDESPREAD IFR CONDS
LIKELY. GFS MOS IS MUCH MORE OPTIMISTIC...BUT PREPONDERANCE OF
EVIDENCE POINTS TO LOW CLOUDS AND EVEN DRIZZLE PERSISTING INTO SAT
MORNING. THICK LOW CLOUDS LINGER FOR THE MORNING HOURS ON
SAT...AND MOST IF NOT ALL OF THE DAY IN THE EAST. A SFC LOW PASSES
WELL TO THE NORTH ON SUNDAY AND THE COLD FRONT ASSOCD WITH IT GOES
THRU VERY SLOWLY. AT LEAST ONE MORE WAVE OF LOW PRESSURE RIDES UP
FROM THE S ON MONDAY...GIVING LITTLE BREAK FROM A MONOTONOUS
MVFR/IFR FORECAST IN RAIN AND LOW CLOUDS/FOG.
OUTLOOK...
SUN...VFR SE...MVFR/IFR IN SHRA/CIGS NW.
MON...MVFR IN WIDESPREAD SH/RA.
MON NITE...CFROPA...NW/UPSLOPE FLOW SHSN.
TUE-WED...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO/LA CORTE
NEAR TERM...DANGELO
SHORT TERM...DANGELO/LA CORTE
LONG TERM...LA CORTE
AVIATION...DANGELO
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
959 AM EST FRI JAN 11 2013
.SYNOPSIS...
A WARM FRONT WILL GRADUALLY MOVE NORTH OUT OF THE GULF OF MEXICO AND
ACROSS THE AREA OVER THE NEXT FEW DAYS. THIS FRONTAL PASSAGE WILL
PROVIDE THE AREA WITH ABOVE NORMAL TEMPERATURES THROUGH THE WEEKEND.
ANOTHER SLOW MOVING FRONT WILL MOVE ACROSS THE AREA FROM THE WEST
EARLY NEXT WEEK BRINGING BETTER CHANCES OF RAIN AND COOLER
TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 955 AM...ANOTHER DAY/ANOTHER COMPLICATED WX PATTERN FOR THE
GSP CWFA. WARM FRONT HAS CROSSED THE SAV RIVER VALLEY WITH AREAS
FROM AND TO GRD INTO THE 60S WITH SLY WINDS. GSP NORTH INTO THE
FOOTHILLS AND I-40 CORRIDOR REMAIN IN THE WEDGE WITH NELY WINDS AND
40S TO 50S. FARTHER EAST THERE APPEARS TO BE A TROF IN PLACE WITH
SELY WINDS AND UPPER 40S TO LOW 50S. 12Z NAM AND LATEST RAP SEEM TO
HAVE PICKED UP ON THESE FEATURES...SO USED MAINLY THOSE MDLS TO
UPDATE THE TEMP/DEW POINT AND WIND GRIDS INTO THE OVERNIGHT HOURS.
THIS KEEPS HIGHS QUITE COOL IN THE HEART OF THE WEDGE WHILE ALLOWING
RISING TEMPS OVER THE TN BORDER COUNTIES...SAV RIVER VALLEY AND THE
SRN AND EASTERN UPSTATE. IF THERE IS ANY DELAY IN THE WARM FRONT OR
IT MOVES FARTHER NORTH OR EAST THAN EXPECTED...THEN ALL THESE TEMPS
COULD BE WRONG. OTHERWISE...HAVE UPDATED TO GO CAT RAIN AND AREAS OF
DRIZZLE MAINLY FROM I-85 NORTH AND WEST THRU THE EARLY AFTERNOON...
THEN TAPER POPS BACK TO THE WEST AS ISENTROPIC LIFT DIMINISHES AS
LOW LEVEL FLOW TURNS SWLY. STILL EXPECT QUITE A BIT OF CLOUDS AROUND
INTO THE OVERNIGHT EVEN WITH DIMINISHING PRECIP.
AS OF DAYBREAK...EXTENSIVE LOW CLOUDS/FOG/DRIZZLE ACROSS THE WESTERN
CAROLINAS AND NORTHEAST GEORGIA. VISIBILITY SHOULD STAY AROUND 1
MILE AT WORST IN MOST PLACES...SO A DENSE FOG ADVISORY IS NOT
ANTICIPATED. THINK UPSLOPE FLOW WILL PRODUCE ENOUGH PRECIPITATION
SIZED HYDROMETEORS THAT WILL SCAVENGE ENOUGH SMALLER DROPLETS TO
KEEP VISIBILITY FROM FALLING BELOW ONE HALF MILE. TEMPS WILL BE
NEARLY STEADY.
FOR TODAY...THE MAIN FEATURE OF INTEREST IS A SHORT WAVE THAT THE
MODELS MOVE ACROSS THE REGION THIS MORNING...FOLLOWED BY A WEAKER
VORT AROUND MIDDAY. THIS FEATURE WAS PARTLY RESPONSIBLE FOR SOME
STRONGER WINDS AT 850MB TRANSLATING ACROSS THE FCST AREA EARLY THIS
MORNING. AS PER USUAL WITH WARM ADVECTION FLOWS...THIS SHOULD NOT
POSE A PROBLEM IN THE MTN VALLEYS...BUT EXPECT SOME STRONGER WINDS
TO PERSIST ON THE RIDGETOPS THROUGH MID MORNING...ALTHO NOT QUITE
ADVISORY LEVEL. THE APPROACH OF THE WAVE SHOULD HELP TO TRIGGER
ADDITIONAL SHOWERS UNTIL ITS PASSAGE LATER THIS MORNING...ESPECIALLY
IN THE STRONG LOW LEVEL UPGLIDE/UPSLOPE FLOW INTO THE SC BLUE RIDGE
AND SRN NC MTNS/UPPER FR BROAD VALLEY. A LIKELY POP STILL LOOKS
APPROPRIATE THERE...FANNING OUT TOWARD THE NW PIEDMONT AS THE WAVE
PASSES THIS MORNING. THE AREA S OF I-85 WILL NOT HAVE THE BENEFIT OF
THE BETTER UPSLOPE AS WIND STARTS TO VEER MORE SW...SO A CHANCE POP
WAS KEPT THERE. TEMPS WILL BE TRICKY TODAY. THE PASSAGE OF THE WAVE
MAY LIFT A WARM FRONTAL BOUNDARY INTO THE FCST AREA THIS
AFTERNOON... AND THIS SEEMS PLAUSIBLE AT LEAST TO AROUND I-85. TEMPS
WERE NUDGED UPWARD NEARLY A CATEGORY IN THESE AREAS. A COOL POOL IS
LIKELY TO PERSIST OVER THE NC FOOTHILLS THOUGH...SO TEMPS WERE KEPT
DOWN IN THE LOW/MID 50S. DEPENDING ON WHERE THE TRANSITION STAYS...
TEMPS COULD BE OFF BY 5 DEGREES OR MORE.
THE FLOW WILL CONTINUE TO GRADUALLY VEER TONIGHT WHICH SHOULD FOCUS
THE WEAK UPSLOPE/UPGLIDE INTO NE GEORGIA AND THE SW MTNS OF NC.
PRECIP CHANCES PARE BACK TO THOSE AREAS THROUGH THE EVENING HOURS AS
MID/UPPER FORCING WILL BE ALMOST NON-EXISTENT. TEMPS SHOULD BE MILD
ONCE AGAIN...GENERALLY A CATEGORY ABOVE OUR NORMAL HIGHS...WITH
PLENTY OF LOW LEVEL MOISTURE. WE MAY DRY OUT ALOFT...WHICH COULD SET
THE STAGE FOR SOME WIDESPREAD DENSE FOG POTENTIAL.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
SATURDAY AND SATURDAY NIGHT...SOUTHWEST FLOW AROUND DEEP SUBTROPICAL
RIDGE OVER THE SE US COAST IMPLIES SOME ISENTROPIC FORCING OVER THE
AREA...BUT AS TEMPERATURES ALOFT WILL ALREADY BE QUITE WARM MODEL
ISENTROPIC OMEGA IS RATHER SMALL. A DECENT AMOUNT OF LOW LEVEL
MOISTURE WILL BE AVAILABLE AND GFS/NAM/SREF ALL DEVELOP SOME PRECIP.
STUDYING THE SPATIAL DISTRIBUTION OF THE PRECIP AND VERY LLVL WINDS
SUGGESTS UPSLOPE WILL BE PRIMARY FORCING. THE SOUTHWEST MTNS ARE
INITIALLY THE FOCUS SAT MRNG...WITH BETTER MOISTURE SHIFTING
NORTHWARD INTO SAT AFTN. WINDS WILL NOT BE ESPECIALLY STRONG NOR WILL
MOISTURE BE PRIME...SO SLIGHT CHANCES ARE APPROPRIATE. AS RIDGE
BEGINS TO BE IMPINGED UPON BY TROUGH ENTERING THE CENTRAL US...WINDS
WILL BACK TO A MORE SOUTHERLY DIRECTION BY SATURDAY EVENING WHICH
WOULD SUGGEST THE BLUE RIDGE ESCARPMENT WOULD BE MOST LIKELY TO SEE
PRECIP AT THAT TIME. HOWEVER LLVL MOISTURE IS NOT SUFFICIENT TO
WARRANT MENTIONABLE POPS AS DRIER AIR IS EVIDENTLY ADVECTED IN FROM
BENEATH THE RIDGE. HIGHS SATURDAY WILL BE QUITE WARM...VERY NEAR OR
BREAKING RECORD HIGHS AT ALL THREE OFFICIAL CLIMATE SITES.
SUNDAY AND SUNDAY NIGHT...MUCH THE SAME STORY UNDER CONTINUING
SOUTHWEST FLOW. HAVE MAINTAINED DRY FCST FOR THE MORNING HOURS...AND
MOST AREAS SHOULD SEE SOME SUNSHINE AT THIS TIME. COLD FRONT LOOKS TO
BE ENTERING WEST TENN AROUND MIDDAY...INCHING EVER CLOSER TO GSP CWFA
THROUGH THE END OF THE SHORT TERM PERIOD...12Z MONDAY. MOISTURE
ADVECTION IS EXPECTED TO IMPROVE BEGINNING SUN AFTN WITH PRECIP
CHANCES INCREASING TO CHANCE IN OUR TN BORDER COUNTIES BY 00Z MONDAY
AND SPREADING EAST/INCREASING FROM THERE. THE FRONT APPEARS TO HAVE
TROUBLE DISLODGING THE INCUMBENT HIGH PRESSURE AND SO THE EASTWARD
EXPANSION OF PRECIP IS FAIRLY SLOW. THE BETTER FRONTOGENETIC/COLD
ADVECTIVE FORCING HAS YET TO REACH THE TN/NC BORDER AT 12Z
MONDAY...BUT MOISTURE IS ABUNDANT BY THAT TIME...SO EVEN THE MODERATE
STRENGTH WARM ADVECTION AHEAD OF THE FRONT SHOULD BE ENOUGH TO
PRODUCE A GOOD BIT OF PRECIP.
PRACTICALLY NO INSTABILITY IS PRESENT IN THE DEEP WARM AIR OVER OUR
REGION DURING THE SHORT TERM...SO THUNDER IS NOT EXPECTED.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 2 AM EST FRIDAY...THE MEDIUM RANGE FCST BEGINS AT 12Z ON
MONDAY WITH UPPER RIDGING OVER THE SE REGION AND AN EXPANSIVE UPPER
TROF DIGGING DOWN OVER THE WESTERN CONUS. THIS RIDGE WILL BEGIN TO
GRADUALLY FLATTEN ON TUES AS THE TROF SLIDES EASTWARD. THE LONG
RANGE MODELS ARE SUGGESTING THAT A CLOSED H5 LOW WILL DEVELOP OVER
THE SW CONUS BY MID WEEK AND TRACK WESTWARD THRU THE END OF THE
PERIOD. THE ECMWF HAS BEEN GENERATING THIS FEATURE FOR THE PAST FEW
DAYS WHILE THE MORE PROGRESSIVE GFS AND CMC HAVE ARE JUST NOW
BEGINNING TO SPIN OFF THE LOW.
AT THE SURFACE...AN ELONGATED AREA OF LOW LVL FRONTAL CONVERGENCE IS
EXPECTED TO MOVE INTO THE WESTERN CAROLINAS BY THE BEGINNING OF THE
PERIOD MONDAY MORNING. THIS CONVERGENCE ZONE IS EXPECTED TO LINGER
OVER THE FCST AREA FOR THE NEXT 36 TO 48 HRS OR SO AS IT REMAINS
SANDWICHED BETWEEN 2 SFC HIGHS. BY WED EVENING...MODEL SOLUTIONS
CONTINUE TO DIVERGE QUITE A BIT WITH THE GFS DRYING OUT THE CWFA AS
CANADIAN HIGH PRESSURE MOVES IN. THE ECMWF ON THE OTHER HAND...SPINS
UP ANOTHER SFC LOW TO OUR SW ON THURS AND MOVES THE LOW TO OUR SOUTH
LATE THURS AND INTO FRI. THIS SCENARIO KEEPS DEEP MOISTURE OVER THE
MUCH OF THE CWFA ON THURS AND EARLY FRI BEFORE DRYING THINGS OUT FRI
AFTERNOON. THE OVERALL FCST CONSENSUS STILL FAVORS THE ECMWF
SOLUTION AND MAINTAINS AT LEAST A SLIGHT CHANCE POP FOR THURS AND
FRI. OUR WESTERN ZONES SHOULD SEE THE HIGHEST QPF AMOUNTS DURING
DAYS 4 THRU 7 WITH VALUES APPROACHING 2 INCHES OVER FAR WESTERN NC.
TEMPS WILL START OUT WELL ABOVE CLIMO ON MONDAY AND STEADILY DROP
THRU THE PERIOD WITH VALUES STILL REMAINING ABOVE NORMAL BY DAY 7.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
AT KCLT...GRIM FCST FOR AVIATION THIS PERIOD. CONDITIONS ARE LIKELY
TO REMAIN IFR OR LOW IFR FOR THE MAJORITY OF THE NEXT 24 HOURS.
CONDITIONAL CLIMATOLOGY AND LAMP GUIDANCE AGREE THAT CEILING WILL
REMAIN IFR THROUGH AT LEAST 18Z. VISIBILITY WILL BE IN AND OUT OF
MVFR/IFR WITH DRIZZLE AND FOG. THINK WE WILL STILL SEE SOME
IMPROVEMENT THIS AFTERNOON AROUND 19Z-21Z WHERE THE VSBY AND CEILING
WILL BECOME MVFR. AS SOON AS THE SUN SETS...EXPECT BOTH TO COME
CRASHING DOWN AGAIN. VERY LOW IFR IS A VERY DISTINCT POSSIBILITY...
BEGINNING AS EARLY AS 03Z. FOR THIS FCST...WILL BRING THEM DOWN ONLY
TO 1 MILE AND OVERCAST 004 BUT THIS COULD EASILY BE BELOW AIRPORT
MINS AFTER 06Z. WIND SHOULD BE GENERALLY ESE THROUGH THE MIDDLE PART
OF THE DAY...BECOMING S OR EVEN SSW IF THE CEILING IMPROVES WITH THE
WARM FRONT LIFTING BRIEFLY N.
ELSEWHERE...VERY SIMILAR TO KCLT. MOST TAF SITES ARE LIKELY TO
REMAIN IFR OR WORSE FOR THE DURATION. ONLY KAND STANDS A DECENT
CHANCE OF IMPROVING TO MVFR LATE THIS AFTERNOON BEFORE COMING BACK
DOWN AGAIN.
OUTLOOK...SOUTHERLY FLOW IS EXPECTED TO MAINTAIN MOISTURE OVER THE
AREA THROUGH THE WEEKEND...RESULTING IN PERIODIC FLIGHT
RESTRICTIONS...ESPECIALLY DURING THE LATE NIGHT/EARLY MORNING HOURS.
PERIODIC LIGHT RAIN WILL ALSO BE POSSIBLE...ESPECIALLY IN AND NEAR
THE MOUNTAINS. RAIN CHANCES MAY INCREASE EARLY NEXT WEEK...AS A COLD
FRONT APPROACHES FROM THE WEST.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT THE FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.CLIMATE...
RECORD HIGH TEMPERATURES FOR SATURDAY...
AVL: 70 IN 1898
CLT: 75 IN 1890
GSP: 70 IN 2000
RECORD HIGH TEMPERATURES FOR SUNDAY...
AVL: 77 IN 1932
CLT: 75 IN 1960
GSP: 79 IN 1911
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...PM/RWH
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...PM
CLIMATE...
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1131 AM CST FRI JAN 11 2013
.UPDATE...
NO FORECAST UPDATE WILL BE ISSUED HERE AT MIDDAY AS THE CURRENT
FORECAST FOR THE NEXT 24 HOURS IS ON TRACK.
CURRENTLY...THE FRONTAL TIMING FOR SATURDAY MORNING THROUGH EARLY
AFTERNOON...AND THE DEVELOPMENT OF CONVECTIVE ACTIVITY ASSOCIATED
WITH THE FRONT IS GOOD. OUR MAIN CONCERN REMAINS WITH THE
POTENTIAL FOR A BRIEF WINTRY MIX LATE SUNDAY NIGHT OVER THE
SOUTHEASTERN COUNTIES AS TEMPERATURES DROP INTO THE 30S. FORECAST
SOUNDINGS OVER THE SOUTHEAST COUNTIES ARE INDICATING THAT THE
PRECIPITATION MAY EXPERIENCE WET-BULB COOLING THAT COULD LEAD TO
SLEET MIXED WITH ANY LINGERING RAIN. HOWEVER...THIS MORNINGS GFS
KEEPS THE PRECIPITATION PROGRESSIVELY MOVING SOUTHEAST AND OUT OF
THE CWA BEFORE THIS TRANSITION CAN TAKE PLACE. AS SUCH...WE HAVE
NOT COMMITTED TO A WINTRY MIX AND WILL AWAIT TODAY/S ECMWF BEFORE
MAKING THE FINAL DECISION. 75
&&
.AVIATION...
TODAY SHOULD BE QUIET FOR THE AREA AIRPORTS. HIGH CLOUDS WILL
CONTINUE TO STREAM ACROSS THE AREA AND WINDS WILL BE BREEZY FROM
THE SOUTH. MVFR CIGS ARE EXPECTED LATE THIS EVENING AND OVERNIGHT
AHEAD OF AN APPROACHING COLD FRONT. HAVE BUMPED UP THE TIMING TO
4Z FOR THE METROPLEX AND 2Z FOR WACO...DUE TO LATEST RAP MODEL
SOUNDINGS. HAVE NOT GONE QUITE AS EARLY AS WHAT THE MODEL IS
SHOWING AS MOST OF THE CONSENSUS IS AFTER 06Z. FRONT SHOULD ARRIVE
TO THE AREA AIRPORTS BETWEEN 13Z AND 16Z. SCATTERED SHOWERS
ACTIVITY ARE LIKELY JUST AHEAD AND BEHIND THE FRONTAL BOUNDARY. WILL
KEEP THE WEATHER AS SHRA...DUE TO WEAK INSTABILITY. CANT RULE OUT
A THUNDERSTORM...ESPECIALLY FOR WACO...BUT PINPOINTING EXACT TIME
IS TOO DIFFICULT AT THIS TIME.
HAMPSHIRE
&&
.PREV DISCUSSION... /ISSUED 427 AM CST FRI JAN 11 2013/
THE LOW CLOUDS FINALLY CLEARED FROM THE REGION YESTERDAY EVENING
BUT HIGH CLOUDS HAVE BEEN SPREADING EAST ACROSS THE FORECAST AREA
OVERNIGHT. IT WILL BE MUCH WARMER TODAY AS SOUTHERLY WINDS
INCREASE DUE TO A TIGHTENING PRESSURE GRADIENT. AS A SHORTWAVE
THAT IS CURRENTLY OVER SOUTHERN CALIFORNIA MOVES EAST AND THEN
NORTHEAST DURING THE NEXT 24-48 HOURS...A COLD FRONT WILL MOVE
SOUTH INTO NORTH TEXAS AFTER MIDNIGHT TONIGHT...AND THROUGH THE
SOUTH BY MIDDAY SATURDAY. WE WILL SEE A CHANCE OF SHOWERS
DEVELOPING AFTER MIDNIGHT TONIGHT...AND A CHANCE OF SHOWERS AND
THUNDERSTORMS AREA WIDE SATURDAY. ALTHOUGH SEVERE WEATHER IS NOT
EXPECTED...A FEW STRONG STORMS WILL BE POSSIBLE ACROSS THE SOUTH.
RAIN CHANCES WILL CONTINUE SATURDAY NIGHT. RAIN CHANCES WILL SLOWLY
TAPER OFF FROM WEST TO EAST LATE SATURDAY NIGHT THROUGH SUNDAY
ACROSS ALL BUT THE SOUTHEAST. TEMPERATURES BY DAYBREAK SUNDAY MAY
APPROACH FREEZING SOME AREAS AS THE PRECIPITATION COMES TO AN END.
FOR NOW...HAVE NOT MENTIONED THE POSSIBILITY OF ANY LIGHT FREEZING
RAIN IN THE PUBLIC FORECAST. THE RAIN CHANCES ACROSS THE SOUTHEAST
WILL END BY LATE SUNDAY NIGHT.
THE ECMWF AND GFS STILL HAVE QUITE DIFFERENT SOLUTIONS AS TO WHAT
WILL HAPPEN WITH AN UPPER LEVEL TROUGH NEXT WEEK. THE ECMWF CUTS
OFF AN UPPER LEVEL LOW OVER ARIZONA AND THEN PUSHES IT EAST ACROSS
TEXAS WEDNESDAY NIGHT AND THURSDAY. IF THIS SOLUTION WERE TO
VERIFY IT WOULD MEAN A CHANCE FOR SOME WINTRY PRECIPITATION
THURSDAY. ON THE OTHER HAND THE GFS AND MOST...BUT NOT ALL...OF
ENSEMBLE SOLUTIONS KEEP THE REGION DRY. FOR NOW...HAVE KEPT THE
CLOUD COVER THROUGH THIS PERIOD OUT OF RESPECT FOR THE ECMWF AND
SOME OF THE GFS ENSEMBLE SOLUTIONS BUT LEFT OUT ANY MENTION OF
PRECIPITATION FOR THE WEDNESDAY NIGHT/THURSDAY SYSTEM. 58
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 71 50 58 33 44 / 5 10 50 40 10
WACO, TX 71 52 62 33 47 / 5 20 50 40 20
PARIS, TX 69 51 61 34 45 / 5 20 80 60 30
DENTON, TX 71 48 56 31 44 / 5 10 50 30 10
MCKINNEY, TX 70 51 57 33 44 / 5 20 50 40 20
DALLAS, TX 71 53 58 34 44 / 5 20 50 40 20
TERRELL, TX 70 54 61 34 45 / 5 20 60 50 30
CORSICANA, TX 72 56 65 35 46 / 5 20 60 50 30
TEMPLE, TX 72 54 66 34 47 / 5 20 50 40 20
MINERAL WELLS, TX 74 45 54 28 44 / 5 10 40 20 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/75
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1113 AM CST FRI JAN 11 2013
.AVIATION...
TODAY SHOULD BE QUIET FOR THE AREA AIRPORTS. HIGH CLOUDS WILL
CONTINUE TO STREAM ACROSS THE AREA AND WINDS WILL BE BREEZY FROM
THE SOUTH. MVFR CIGS ARE EXPECTED LATE THIS EVENING AND OVERNIGHT
AHEAD OF AN APPROACHING COLD FRONT. HAVE BUMPED UP THE TIMING TO
4Z FOR THE METROPLEX AND 2Z FOR WACO...DUE TO LATEST RAP MODEL
SOUNDINGS. HAVE NOT GONE QUITE AS EARLY AS WHAT THE MODEL IS
SHOWING AS MOST OF THE CONSENSUS IS AFTER 06Z. FRONT SHOULD ARRIVE
TO THE AREA AIRPORTS BETWEEN 13Z AND 16Z. SCATTERED SHOWERS
ACTIVITY ARE LIKELY JUST AHEAD AND BEHIND THE FRONTAL BOUNDARY. WILL
KEEP THE WEATHER AS SHRA...DUE TO WEAK INSTABILITY. CANT RULE OUT
A THUNDERSTORM...ESPECIALLY FOR WACO...BUT PINPOINTING EXACT TIME
IS TOO DIFFICULT AT THIS TIME.
HAMPSHIRE
&&
.PREV DISCUSSION... /ISSUED 427 AM CST FRI JAN 11 2013/
THE LOW CLOUDS FINALLY CLEARED FROM THE REGION YESTERDAY EVENING
BUT HIGH CLOUDS HAVE BEEN SPREADING EAST ACROSS THE FORECAST AREA
OVERNIGHT. IT WILL BE MUCH WARMER TODAY AS SOUTHERLY WINDS
INCREASE DUE TO A TIGHTENING PRESSURE GRADIENT. AS A SHORTWAVE
THAT IS CURRENTLY OVER SOUTHERN CALIFORNIA MOVES EAST AND THEN
NORTHEAST DURING THE NEXT 24-48 HOURS...A COLD FRONT WILL MOVE
SOUTH INTO NORTH TEXAS AFTER MIDNIGHT TONIGHT...AND THROUGH THE
SOUTH BY MIDDAY SATURDAY. WE WILL SEE A CHANCE OF SHOWERS
DEVELOPING AFTER MIDNIGHT TONIGHT...AND A CHANCE OF SHOWERS AND
THUNDERSTORMS AREA WIDE SATURDAY. ALTHOUGH SEVERE WEATHER IS NOT
EXPECTED...A FEW STRONG STORMS WILL BE POSSIBLE ACROSS THE SOUTH.
RAIN CHANCES WILL CONTINUE SATURDAY NIGHT. RAIN CHANCES WILL SLOWLY
TAPER OFF FROM WEST TO EAST LATE SATURDAY NIGHT THROUGH SUNDAY
ACROSS ALL BUT THE SOUTHEAST. TEMPERATURES BY DAYBREAK SUNDAY MAY
APPROACH FREEZING SOME AREAS AS THE PRECIPITATION COMES TO AN END.
FOR NOW...HAVE NOT MENTIONED THE POSSIBILITY OF ANY LIGHT FREEZING
RAIN IN THE PUBLIC FORECAST. THE RAIN CHANCES ACROSS THE SOUTHEAST
WILL END BY LATE SUNDAY NIGHT.
THE ECMWF AND GFS STILL HAVE QUITE DIFFERENT SOLUTIONS AS TO WHAT
WILL HAPPEN WITH AN UPPER LEVEL TROUGH NEXT WEEK. THE ECMWF CUTS
OFF AN UPPER LEVEL LOW OVER ARIZONA AND THEN PUSHES IT EAST ACROSS
TEXAS WEDNESDAY NIGHT AND THURSDAY. IF THIS SOLUTION WERE TO
VERIFY IT WOULD MEAN A CHANCE FOR SOME WINTRY PRECIPITATION
THURSDAY. ON THE OTHER HAND THE GFS AND MOST...BUT NOT ALL...OF
ENSEMBLE SOLUTIONS KEEP THE REGION DRY. FOR NOW...HAVE KEPT THE
CLOUD COVER THROUGH THIS PERIOD OUT OF RESPECT FOR THE ECMWF AND
SOME OF THE GFS ENSEMBLE SOLUTIONS BUT LEFT OUT ANY MENTION OF
PRECIPITATION FOR THE WEDNESDAY NIGHT/THURSDAY SYSTEM.
58
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 71 50 58 33 44 / 5 10 50 40 10
WACO, TX 71 52 62 33 47 / 5 20 50 40 20
PARIS, TX 69 51 61 34 45 / 5 20 80 60 30
DENTON, TX 71 48 56 31 44 / 5 10 50 30 10
MCKINNEY, TX 70 51 57 33 44 / 5 20 50 40 20
DALLAS, TX 71 53 58 34 44 / 5 20 50 40 20
TERRELL, TX 70 54 61 34 45 / 5 20 60 50 30
CORSICANA, TX 72 56 65 35 46 / 5 20 60 50 30
TEMPLE, TX 72 54 66 34 47 / 5 20 50 40 20
MINERAL WELLS, TX 74 45 54 28 44 / 5 10 40 20 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
85/85
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1000 PM CST SAT JAN 12 2013
.SHORT TERM...TONIGHT THROUGH TUESDAY
240 PM CST SAT JAN 12 2013
THE MAIN FOCUS IN THE SHORT TERM IS WITH THE SNOW POTENTIAL
TONIGHT ACROSS FAR SOUTHWEST WISCONSIN AND NORTHEAST IOWA ALONG
WITH TEMPERATURES INTO EARLY NEXT WEEK.
CURRENTLY...AN UPPER LEVEL TROUGH IS DIGGING SOUTH ACROSS THE
PLAINS WHILE A RIDGE OF HIGH PRESSURE BECOMES MORE AMPLIFIED
ACROSS THE EAST COAST. AT THE SURFACE...COLDER AIR IS DROPPING
DOWN FROM CENTRAL CANADA DOWN THROUGH THE PLAINS ON THE BACK SIDE
OF A LOW THAT IS MOVING INTO WESTERN QUEBEC. AN INVERTED TROUGH
EXTENDS TO THE SOUTHWEST OUT OF THIS LOW AND HAS HELPED TO POOL
SOME HIGHER LOW LEVEL HUMIDITY THAT HAPPENS TO BE IN THE -8C TO
-12C RANGE...WHICH INTRODUCES ICE INTO THE CLOUD LAYER. OVERALL
FORCING IS WEAK BUT ENOUGH FROM THE SURFACE TROUGH TO PRODUCE SNOW
SHOWERS AND FLURRIES ACROSS THE REGION.
12.12Z NAM/GFS AND 12.18Z RAP SOUNDINGS SHOW THE THIN LOW LEVEL
CLOUD LAYER STICKING AROUND OVERNIGHT INTO TOMORROW AND DEEPENING
AS A LOW PRESSURE SYSTEM TRACKS TO THE NORTHEAST FROM THE SOUTHERN
PLAINS ON INTO MICHIGAN TONIGHT. THE QUESTION WITH THIS SYSTEM HAS
BEEN HOW FAR WEST THE SNOW WOULD MAKE IT. THE PREVIOUS RUNS OF THE
ECMWF HAD BEEN THE FURTHEST WEST OVER THE PAST FEW DAYS...BUT NOW
HAS COME INTO A CONSENSUS WITH WHAT THE 12.12Z NAM/GFS/GEM ARE
SHOWING WITH THE TRACK FURTHER TO THE EAST WITH JUST A BRIEF
PERIOD OF LIGHT SNOW OCCURRING ACROSS NORTHEAST IOWA AND FAR
SOUTHWEST WISCONSIN. 12.12Z NAM/GFS AND 12.18Z RAP CROSS SECTIONS
SHOWS AN ASCENDING BAND OF FRONTOGENESIS THAT IS CLOSER TO THE
SURFACE TO THE SOUTHEAST AND MORE OF A MID LEVEL CIRCULATION
ACROSS THE REST OF THE FORECAST AREA. THIS FORCING SHOULD BE
ENOUGH TO AT LEAST PRODUCE SOME FLURRIES...BUT CAN NOT COMPLETELY
RULE OUT THAT SOME SNOW COULD MAKE IT FURTHER WEST DEPENDING ON
HOW STRONG THE CIRCULATION GETS. THE SNOW WILL DEVELOP NORTHWARD
THIS EVENING BEFORE QUICKLY GETTING SHUNTED OFF TO THE EAST BY DAY
BREAK. ACCUMULATIONS ARE EXPECTED TO BE ON THE LIGHT SIDE AT LESS
THAN AN INCH ACROSS GRANT COUNTY.
AFTER THIS SYSTEM MOVES THROUGH...THE COLD AIR WILL MOVE IN ACROSS
THE REGION FROM THE NORTHWEST AND LINGER INTO THE EARLY PART OF
NEXT WEEK. HOW FAR TEMPERATURES ARE ABLE TO DROP IS OF QUESTION
RIGHT NOW SINCE MOST OF THE AREAS SNOW PACK HAS ERODED DUE TO THE
FOG...WIND...RAIN AND WARM AIR THAT WAS AROUND EARLIER THIS WEEK.
HAVE NOT MADE MANY ADJUSTMENTS TO THE GOING FORECAST WITH SUNDAY
LOOKING LIKE THE COLDEST DAY OVER THE NEXT WEEK.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
240 PM CST SAT JAN 12 2013
THE NEXT CHANCE FOR SNOW COMES IN TUESDAY NIGHT INTO WEDNESDAY AS
A MID LEVEL SHORT WAVE TROUGH DIVES DOWN FROM NORTHWEST CANADA
DOWN INTO THE UPPER MISSISSIPPI RIVER VALLEY. THERE ARE SOME
DIFFERENCES BETWEEN THE LONG TERM GUIDANCE WITH THIS SYSTEM WITH
THE 12.12Z GFS SHOWING A MUCH MORE COMPACT TROUGH THAT COMES
THROUGH FASTER THAN WHAT THE 12.12Z ECMWF IS ADVERTISING. THIS
LEADS TO A DEEPER SURFACE LOW THAT DIVES FURTHER SOUTH ON THE GFS
COMPARED TO THE ECMWF AS WELL. BECAUSE OF THESE DIFFERENCES...HAVE
NOT HIT THE PRECIPITATION CHANCES TO HIGH YET...BUT OVERALL THE
BETTER CHANCES FOR SEEING THE SNOW WILL BE ACROSS THE NORTHERN
PORTION OF THE FORECAST AREA. WITH THERE NOT BEING MUCH OF A SHIFT
IN THE UPPER LEVEL PATTERN...THERE COULD BE A FEW MORE CHANCES OF
LIGHT SNOW NEXT WEEK BUT MUCH OF THE FORCING APPEARS TO BE GOING
JUST NORTH OF THE REGION. WITH THE PATTERN NOT SHIFTING
MUCH...TEMPERATURES WILL NOT VARY MUCH EITHER AND REMAIN FAIRLY
SEASONAL.
&&
.AVIATION...THROUGH 06Z MONDAY
1000 PM CST SAT JAN 12 2013
A WEAK HIGH PRESSURE RIDGE HAS BUILT IN FROM NORTHWEST IOWA INTO
NORTHWEST WISCONSIN. DRIER AIR AND ANTICYCLONIC FLOW ASSOCIATED
WITH THIS RIDGE HAS HELPED SCATTER OUT LOW CLOUDS ACROSS MUCH OF
CENTRAL AND SOUTHERN MINNESOTA...INCLUDING KRST...THOUGH THERE
ARE A FEW PATCHES OF BROKEN TO OVERCAST MVFR CEILINGS. THE
FORECAST IS THAT THE RIDGE WILL REMAIN NEARLY STATIONARY THROUGH
06Z MONDAY. AS A RESULT...KRST MAY END UP WITH CLEAR OR SCATTERED
MVFR CEILINGS. DID INCLUDE A TEMPO GROUP BETWEEN 06-10Z FOR BROKEN
MVFR CEILINGS SEEING SOME PATCHES OF THIS NEAR I-35. FOR
KLSE...THE SITE IS A LITTLE MORE INTO THE TRAPPED LOW LEVEL
MOISTURE...THUS BELIEVE A BROKEN MVFR CEILING MAY HOLD IN PLACE
THROUGH AT LEAST 03Z MONDAY. STILL...CONCERNED THAT SOME DRIER AIR
FROM MINNESOTA MAY ADVECT IN AND HAVE COVERED THIS WITH A 06-10Z
TEMPO FOR SCATTERING OUT OF THE LOW CLOUDS. BETTER SHOT FOR
CLEARING WOULD BE AFTER 03Z WHEN THE RIDGE BUILDS IN. NOTE...IF
THE DRIER AIR MAKES MORE OF AN IN-ROAD THIS MORNING...VFR
CONDITIONS ARE LIKELY. A FEW FLURRIES MAY OCCUR THROUGHOUT THE DAY
AT KLSE...BUT NOTHING TO REDUCE VISIBILITY.
WINDS AT BOTH TAF SITES LOOK TO HOLD FAIRLY STEADY THROUGH 06Z
MONDAY...OUT OF THE NORTHWEST BETWEEN 10-15 KT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
240 PM CST SAT JAN 12 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
505 PM CST SAT JAN 12 2013
.SHORT TERM...TONIGHT THROUGH TUESDAY
240 PM CST SAT JAN 12 2013
THE MAIN FOCUS IN THE SHORT TERM IS WITH THE SNOW POTENTIAL
TONIGHT ACROSS FAR SOUTHWEST WISCONSIN AND NORTHEAST IOWA ALONG
WITH TEMPERATURES INTO EARLY NEXT WEEK.
CURRENTLY...AN UPPER LEVEL TROUGH IS DIGGING SOUTH ACROSS THE
PLAINS WHILE A RIDGE OF HIGH PRESSURE BECOMES MORE AMPLIFIED
ACROSS THE EAST COAST. AT THE SURFACE...COLDER AIR IS DROPPING
DOWN FROM CENTRAL CANADA DOWN THROUGH THE PLAINS ON THE BACK SIDE
OF A LOW THAT IS MOVING INTO WESTERN QUEBEC. AN INVERTED TROUGH
EXTENDS TO THE SOUTHWEST OUT OF THIS LOW AND HAS HELPED TO POOL
SOME HIGHER LOW LEVEL HUMIDITY THAT HAPPENS TO BE IN THE -8C TO
-12C RANGE...WHICH INTRODUCES ICE INTO THE CLOUD LAYER. OVERALL
FORCING IS WEAK BUT ENOUGH FROM THE SURFACE TROUGH TO PRODUCE SNOW
SHOWERS AND FLURRIES ACROSS THE REGION.
12.12Z NAM/GFS AND 12.18Z RAP SOUNDINGS SHOW THE THIN LOW LEVEL
CLOUD LAYER STICKING AROUND OVERNIGHT INTO TOMORROW AND DEEPENING
AS A LOW PRESSURE SYSTEM TRACKS TO THE NORTHEAST FROM THE SOUTHERN
PLAINS ON INTO MICHIGAN TONIGHT. THE QUESTION WITH THIS SYSTEM HAS
BEEN HOW FAR WEST THE SNOW WOULD MAKE IT. THE PREVIOUS RUNS OF THE
ECMWF HAD BEEN THE FURTHEST WEST OVER THE PAST FEW DAYS...BUT NOW
HAS COME INTO A CONSENSUS WITH WHAT THE 12.12Z NAM/GFS/GEM ARE
SHOWING WITH THE TRACK FURTHER TO THE EAST WITH JUST A BRIEF
PERIOD OF LIGHT SNOW OCCURRING ACROSS NORTHEAST IOWA AND FAR
SOUTHWEST WISCONSIN. 12.12Z NAM/GFS AND 12.18Z RAP CROSS SECTIONS
SHOWS AN ASCENDING BAND OF FRONTOGENESIS THAT IS CLOSER TO THE
SURFACE TO THE SOUTHEAST AND MORE OF A MID LEVEL CIRCULATION
ACROSS THE REST OF THE FORECAST AREA. THIS FORCING SHOULD BE
ENOUGH TO AT LEAST PRODUCE SOME FLURRIES...BUT CAN NOT COMPLETELY
RULE OUT THAT SOME SNOW COULD MAKE IT FURTHER WEST DEPENDING ON
HOW STRONG THE CIRCULATION GETS. THE SNOW WILL DEVELOP NORTHWARD
THIS EVENING BEFORE QUICKLY GETTING SHUNTED OFF TO THE EAST BY DAY
BREAK. ACCUMULATIONS ARE EXPECTED TO BE ON THE LIGHT SIDE AT LESS
THAN AN INCH ACROSS GRANT COUNTY.
AFTER THIS SYSTEM MOVES THROUGH...THE COLD AIR WILL MOVE IN ACROSS
THE REGION FROM THE NORTHWEST AND LINGER INTO THE EARLY PART OF
NEXT WEEK. HOW FAR TEMPERATURES ARE ABLE TO DROP IS OF QUESTION
RIGHT NOW SINCE MOST OF THE AREAS SNOW PACK HAS ERODED DUE TO THE
FOG...WIND...RAIN AND WARM AIR THAT WAS AROUND EARLIER THIS WEEK.
HAVE NOT MADE MANY ADJUSTMENTS TO THE GOING FORECAST WITH SUNDAY
LOOKING LIKE THE COLDEST DAY OVER THE NEXT WEEK.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
240 PM CST SAT JAN 12 2013
THE NEXT CHANCE FOR SNOW COMES IN TUESDAY NIGHT INTO WEDNESDAY AS
A MID LEVEL SHORT WAVE TROUGH DIVES DOWN FROM NORTHWEST CANADA
DOWN INTO THE UPPER MISSISSIPPI RIVER VALLEY. THERE ARE SOME
DIFFERENCES BETWEEN THE LONG TERM GUIDANCE WITH THIS SYSTEM WITH
THE 12.12Z GFS SHOWING A MUCH MORE COMPACT TROUGH THAT COMES
THROUGH FASTER THAN WHAT THE 12.12Z ECMWF IS ADVERTISING. THIS
LEADS TO A DEEPER SURFACE LOW THAT DIVES FURTHER SOUTH ON THE GFS
COMPARED TO THE ECMWF AS WELL. BECAUSE OF THESE DIFFERENCES...HAVE
NOT HIT THE PRECIPITATION CHANCES TO HIGH YET...BUT OVERALL THE
BETTER CHANCES FOR SEEING THE SNOW WILL BE ACROSS THE NORTHERN
PORTION OF THE FORECAST AREA. WITH THERE NOT BEING MUCH OF A SHIFT
IN THE UPPER LEVEL PATTERN...THERE COULD BE A FEW MORE CHANCES OF
LIGHT SNOW NEXT WEEK BUT MUCH OF THE FORCING APPEARS TO BE GOING
JUST NORTH OF THE REGION. WITH THE PATTERN NOT SHIFTING
MUCH...TEMPERATURES WILL NOT VARY MUCH EITHER AND REMAIN FAIRLY
SEASONAL.
&&
.AVIATION...TONIGHT AND SUNDAY
504 PM CST SAT JAN 12 2013
COLD...CYCLONIC LOW LEVEL FLOW...COMBINED WITH MOISTURE TRAPPED
UNDERNEATH THIS MORNINGS COLD FRONTAL PASSAGE...WILL MAINTAIN
MVFR STRATUS AT BOTH TAF SITES THROUGH SUNDAY. IT IS POSSIBLE THAT
CEILINGS COULD GO VFR AT KLSE OCCASIONALLY...SINCE THE CEILING IS
HOVERING AROUND 3000 FT. FOR NOW PLAYED THE FORECAST WITH THE
CEILING THERE AT HIGH MVFR...3000 FT. WITH THE STRATUS LOCATED IN
THE DENDRITIC GROWTH ZONE...OFF AND ON FLURRIES/LIGHT SNOW SHOWERS
ARE EXPECTED. VISIBILITIES SHOULD GENERALLY STAY VFR...THOUGH
COULD BRIEFLY DROP TO MVFR AT TIMES. WINDS ALSO LOOK TO REMAIN
FAIRLY STEADY THROUGH SUNDAY...BECOMING NORTHWESTERLY THIS EVENING
AND HOLDING IN THE 8-15 KT RANGE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
240 PM CST SAT JAN 12 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1157 AM CST FRI JAN 11 2013
.SHORT TERM...
1157 AM CST FRI JAN 11 2013
VISIBILITY HAS REMAINED LOW AT A QUARTER MILE OR LESS ACROSS THE
REGION AND HAS NOT IMPROVED MUCH AT ALL THROUGH THE MORNING WITH
TEMPERATURES STICKING AROUND THE MID 30S. THE INCREASING WINDS
APPEAR TO HAVE ACTUALLY MADE CONDITIONS WORSE WITH CREATING AN
ADVECTION FOG THAT IS ERODING MORE OF THE SNOW PACK. THE WORST
VISIBILITIES ARE NORTH OF A WARM FRONT THAT IS CURRENTLY IN SOUTHERN
IOWA AND EXPECT THAT TO BE THE CASE THROUGH THIS AFTERNOON AND
EVENING. THEREFORE...HAVE EXTENDED THE DENSE FOG ADVISORY THROUGH
MIDNIGHT. THAT TIMING COULD END UP BEING TOO LONG...OR TOO SHORT
DEPENDING ON WHAT OCCURS THIS EVENING. THE 11.16Z TO 11.19Z RUNS
OF THE HRRR HAVE DONE A GOOD JOB OF SHOWING THE LOWER
VISIBILITIES...PARTICULARLY WITH THE HINTING AT SLIGHTLY BETTER
CONDITIONS IN THE COULEES...AND SHOWS AN IMPROVEMENT FROM THE
SOUTH THIS EVENING AS THE WARM FRONT LIFTS NORTH. CURRENT THINKING
IS THAT VISIBILITY WILL IMPROVE FROM THE SOUTH TO NORTH BETWEEN
6PM TO MIDNIGHT TONIGHT WHERE WE CAN CANCEL THE ADVISORY EARLY IN
THE SOUTH IF THE CONDITIONS DO IN FACT IMPROVE. THE WILD CARD IS
THAT ONCE THE WARM FRONT MOVES THROUGH THAT THE STRONGER SOUTHWEST
WINDS AND WARMER AIR COULD JUST MAKE THINGS WORSE AGAIN WITH THE
ERODING SNOW PACK. FOR NOW...HAVE TRENDED TOWARD THE HRRR SINCE
THE OBS ACROSS SOUTHERN IOWA DO IMPROVE SUBSTANTIALLY SOUTH OF THE
FRONT. SHOULD THE DENSE FOG CONTINUE INTO THE OVERNIGHT HOURS...IT
DEFINITELY WILL COME TO AN END ONCE THE POTENT COLD FRONT COMES
THROUGH AND INCREASES WINDS INTO THE 25 TO 40 MPH RANGE.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
300 AM CST FRI JAN 11 2013
THE GFS AND 11.00Z ECMWF AGREE THAT THE POLAR VORTEX WILL BE
MOVING SOUTH FROM OVER NUNAVUT TO NEAR HUDSONS BAY. THIS WILL PUSH
A COLD FRONT ACROSS THE UPPER MIDWEST DURING THE MIDDLE OF NEXT
WEEK. THE GFS KEEPS THE SURFACE LOW OFF TO THE NORTHEAST OVER
ONTARIO AND IS QUICKER TO BRING THE FRONT THROUGH ON TUESDAY
NIGHT. THE ECMWF AND 11.00Z GEM INDICATE THE SURFACE LOW WILL MOVE
ACROSS THE UPPER MIDWEST AND GREAT LAKES AND DO NOT BRING THE
FRONT THROUGH UNTIL WEDNESDAY OR WEDNESDAY NIGHT. FOR NOW...WILL
STAY WITH THE MODEL CONSENSUS AND CARRY A CHANCE OF SNOW FOR
TUESDAY NIGHT AND WEDNESDAY.
&&
.AVIATION...THROUGH 18Z SATURDAY
1157 AM CST FRI JAN 11 2013
LOW VISIBILITY AND CEILINGS WILL PERSIST AT RST AND LSE THROUGH
TONIGHT AS A WARM AND MOIST AIR MASS SITS ACROSS THE REGION.
THE COMBINATION OF THIS AIR MASS WITH A MELTING SNOW PACK HAS LED
TO WIDESPREAD DENSE FOG WITH VISIBILITIES DROPPING TO A QUARTER
MILE OR LESS THROUGHOUT THE REGION. SOME OF THE RIVER VALLEY
LOCATIONS HAVE BEEN SLIGHTLY HIGHER WITH THE VISIBILITY AT TIMES
BUT CEILINGS HAVE REMAINED LOW AT A FEW HUNDRED FEET. LITTLE
CHANGE IN THESE CONDITIONS ARE EXPECTED THROUGH TONIGHT AS A WARM
FRONT MOVES IN FROM THE SOUTH AS A LOW PRESSURE SYSTEM TRACKS
THROUGH THE PLAINS ON INTO MINNESOTA. THERE MAY BE SOME
IMPROVEMENTS THIS EVENING AFTER THE WARM FRONT MOVES THROUGH...BUT
THE WARMER AIR AND STRONGER WINDS MAY JUST LEAD TO MOVE SNOW MELT
AND CONTINUED LOW VISIBILITIES. LOW LEVEL WINDS WILL BE
STRENGTHENING AHEAD OF A COLD FRONT THAT WILL MOVE THROUGH
OVERNIGHT...WITH LOW LEVEL WIND SHEAR OCCURRING FROM SFC WINDS
AROUND 15KTS AND 2KFT WINDS STRENGTHENING TO 50-60KTS. AFTER THE
COLD FRONT MOVES THROUGH...VISIBILITY AND CEILINGS WILL IMPROVE TO
MVFR BUT WINDS WILL RAPIDLY INCREASE TO BEING OUT OF THE WEST-
SOUTHWEST AT 20-35KTS. THE BACK EDGE OF THE SYSTEM WILL THEN MOVE
THROUGH TOMORROW MORNING WITH SOME SNOW POSSIBLE THAT COULD BRING
VISIBILITY BACK DOWN TO IFR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
1157 AM CST FRI JAN 11 2013
WI...DENSE FOG ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ017-029-
032>034-041>044-053>055-061.
MN...DENSE FOG ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR MNZ079-086>088-
094>096.
IA...DENSE FOG ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR IAZ008>011-018-
019-029-030.
&&
$$
SHORT TERM...HALBACH
LONG TERM...04
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
417 AM EST SUN JAN 13 2013
...DENSE FOG ADVY FOR PARTS OF THE AREA THIS MORNING...
...NEAR RECORD WARMTH THROUGH TUESDAY...
.CURRENTLY...LATEST RAP ANALYSIS SHOWS 500 MB HIGH PRES RIDGE LOCATED
OVER WRN ATLC ALONG ABOUT 75W. SFC HIGH PRES APPEARS TO BE LOCATED
NEAR 30N75W. ONCE AGAIN...HIGH DEWPOINT AIR IN THE LOWER 60S TO THE
UPPER 50S IS RESULTING IN EARLY MORNING FOG DEVELOPMENT...INITIALLY
THAT FORMED ALONG THE COAST THAT IS SEA FOG. DENSE FOG ADVY WAS
ISSUED EARLIER TO ACCOUNT FOR LOW VISIBILITIES OVER THE IMMEDIATE
COASTAL AREAS NORTH OF FERNANDINA BEACH. THIS ADVISORY MAY BE
EXPANDED IN COVERAGE.
.SHORT TERM...TODAY THROUGH MONDAY...
EARLY MORNING FOG EXPECTED THAT SHOULD DISSIPATE BY AROUND 14Z-15Z
INSOLATION BURNS IT OFF. IN FACT...IT MAY DISSIPATE FASTER THAN
YESTERDAY GIVEN THE SHALLOWNESS OF THE MOISTURE PER NAM BUFR
SOUNDINGS. HOWEVER...SEA FOG SHOULD PERSIST LONGER OVER THE SE GA
MARINE WATERS FROM 0-20 NM THROUGH THE EARLY AFTN. OTHERWISE..THE
STAGNANT WX PATTERN FEATURING THE DEEP LAYER HIGH PRES TO OUR E WILL
CONTINUE THE ABOVE NORMAL TEMPS TODAY...SIMILAR TO YESTERDAY...WITH
MID 70S NEAR THE COAST AND NEAR OR JUST ABOVE 80 DEG INLAND. WENT
JUST ABOVE GUIDANCE BASED ON PERSISTENCE. RECORD HIGHS POSSIBLE AT
ALMA AND JAX TODAY WHERE THEY ARE CURRENTLY 80 AND 82 DEGREES
RESPECTIVELY. E COAST SEA BREEZE EXPECTED ONCE AGAIN IN THE
AFTN...AND SHOULD MOVE WELL INLAND LIKE THE PAST COUPLE OF DAYS.
TONIGHT...AN ONSHORE FLOW IN THE EVENING WILL ENSURE THE BOUNDARY
LAYER AIRMASS WILL REMAIN MOIST. AREAS OF FOG EXPECTED TO DEVELOP
AGAIN BUT SHOULD AGAIN BE MORE COMMON ACROSS ERN PARTS OF SE GA AND
NE FL WHERE A SHARPER INVERSION IS EXPECTED. DENSE FOG WILL BE
POSSIBLE BUT A FEW STRATO CLDS MAY SERVE TO KEEP IT CONFINED TO
SMALL AREAS. MONDAY...SFC RIDGE WILL SHIFT A BIT FURTHER S ACROSS S
CENTRAL FL WHILE A SLOW MOVING COLD FRONT MOVES INTO N CENTRAL GA TO
SRN AL. THE STOUT RIDGE KEEP OUR AREA DRY WITH DEEP S AND SW FLOW
AND WARM TEMPS AGAIN. HIGHS AROUND 80 INLAND AND MID 70S NEAR THE
COAST. E COAST SEA BREEZE WILL GET A LITTLE LATER START DUE TO
SLIGHTLY STRONGER S-SW WINDS.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
THIS PERIOD WILL FEATURE A TRANSITION FROM UNSEASONABLY WARM AND
DRY CONDITIONS TO CLOUDY AND COOL CONDITIONS WITH RAIN SHOWERS BY
THURSDAY. HIGH PRESSURE WILL REMAIN THE DOMINANT FEATURE THROUGH
TUESDAY NIGHT AND WE HAVE REMOVED ALL MENTION OF POPS AND KEPT ALL
AREAS DRY THROUGH THIS PERIOD. TEMPERATURES WILL REMAIN WELL ABOVE
NORMAL THROUGH WEDNESDAY.
THE MODELS HAVE REALLY COME INTO EXCELLENT AGREEMENT WITH REGARDS
TO THE SYNOPTIC PATTERN ON WEDNESDAY AND THURSDAY...THUS RESULTING
IN AN INCREASE IN FORECAST CONFIDENCE. A SLOW MOVING COLD FRONT
WILL STRUGGLE TO CUT INTO THE RIDGE UNTIL THE NEXT UPPER WAVE
PIVOTS ACROSS THE DEEP SOUTH WEDNESDAY NIGHT INTO THURSDAY. THIS
WILL FINALLY BE ENOUGH TO PUSH THE FRONT SOUTH...PUSHING THROUGH
SOUTHEAST GEORGIA WEDNESDAY NIGHT AND THEN THROUGH NORTHERN
FLORIDA ON THURSDAY. BOTH GFS AND ECMWF HAVE TRENDED TOWARDS A
WETTER SOLUTION WITH THE FRONTAL PASSAGE...PARTICULARLY ON
THURSDAY AS THE UPPER SUPPORT INCREASES WITH THE UPPER WAVE. WILL
GO WITH A LOW CHANCE OF RAIN BEGINNING IN SOUTHEAST GEORGIA
WEDNESDAY AFTERNOON AND THEN INCREASE POPS TO 30 TO 40 PERCENT
ACROSS GEORGIA AND THE SUWANNEE RIVER VALLEY OF NORTH FLORIDA
WEDNESDAY NIGHT AS THE FRONT PUSHES SOUTH. WILL FURTHER INCREASE
POPS UP TO 50 PERCENT ON THURSDAY AND SHOW A TREND FROM NORTH TO
SOUTH THROUGH THE DAY. MOST AREAS WILL ACTUALLY SEE FALLING
TEMPERATURES ON THURSDAY WITH HIGHS RANGING FROM THE LOW 60S NORTH
TO THE MID 70S SOUTH.
BEYOND THURSDAY...THE FORECAST BECOMES A LITTLE MORE UNCERTAIN BUT
THE LATEST MODEL RUNS HAVE TRENDED TOWARDS A WETTER SOLUTION
FRIDAY AND SATURDAY WITH A CONTINUATION OF CLOUDY AND COOLER
CONDITIONS. THE FLOW WILL QUICKLY TURN TO THE NORTHEAST THURSDAY
NIGHT AS STRONG HIGH PRESSURE MOVES TO THE MID-ATLANTIC SEABOARD.
THIS WILL KEEP THE FRONT FROM MOVING TOO FAR SOUTH WHICH IN TURN
WILL ACT TO KEEP DEEPER LAYER MOISTURE OVER AT LEAST THE SOUTH
HALF OF THE FORECAST AREA. AT THE SAME TIME...THE NORTHEAST SURGE
IS PROGGED TO BE STRONG ENOUGH TO RESULT IN SUFFICIENT MOISTURE
CONVERGENCE TO PRODUCE SOME RAIN SHOWERS...WITH THE HIGHEST COVERAGE
EXPECTED ALONG THE COAST. WILL HIGHLIGHT THIS POTENTIAL BY
INCREASING POPS IN THESE AREAS TO 20 TO 30 PERCENT ON FRIDAY AND
SATURDAY.
&&
.AVIATION...
FOG FORECAST IS A CHALLENGE THIS MORNING. SO FAR...FOG HAS BEEN
SLOW TO DEVELOP BUT CONDITIONS REMAIN FAVORABLE FOR A PERIOD OF
LIFR TO VLIFR CONDITIONS AROUND THE TIME OF SUNRISE THIS MORNING.
CONDITIONS WILL IMPROVE TO VFR BY MID MORNING.
&&
.MARINE...MAIN CONCERN IN THE SHORT TERM WILL BE SEA FOG IN THE
EARLY MORNING AND AFTN ALONG THE NEARSHORE ZONES GENERALLY N OF
MAYPORT AND FERNANDINA BEACH. THE FOG WILL LIKELY RETURN AGAIN EARLY
MONDAY MORNING. WINDS/SEAS WILL BE BELOW ADVY CRITERIA THROUGH EARLY
WEEK.
RIP CURRENTS: LOW RISK RIP CURRENTS TODAY-MONDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 80 57 80 54 / 10 10 10 10
SSI 70 57 73 57 / 0 10 10 0
JAX 80 56 80 55 / 0 10 10 0
SGJ 77 59 75 58 / 0 0 0 0
GNV 82 56 80 54 / 0 0 0 0
OCF 82 58 81 55 / 0 0 0 0
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR BRANTLEY-
COASTAL CAMDEN-COASTAL GLYNN-INLAND CAMDEN-INLAND GLYNN-
WAYNE.
AM...DENSE FOG ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ALTAMAHA
SOUND GA TO FERNANDINA BEACH FL OUT 20 NM.
&&
$$
SHASHY/SHULER/
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
348 AM CST SUN JAN 13 2013
.DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* PATCHY FZDZ THROUGH DAYBREAK.
* IFR/LOW MVFR CIGS SLOW TO IMPROVE THROUGH THE DAY. THE
POTENTIAL FOR FZDZ AFTER 10Z AS STEADIER PRECIPITATION ENDS.
* A SLIGHT CHANCE FOR -SN LATE THIS AFTERNOON.
* NW WINDS BECOMING WNW THIS AFTERNOON AND GUSTY INTO THE EVE.
//DISCUSSION...UPDATED 06Z...
LOW PRESSURE WILL MOVE NORTHEAST ACROSS INDIANA THROUGH DAYBREAK.
THERE APPEARS A WINDOW OF ABOUT 3-4 MORE HOURS /THROUGH 09Z-10Z/
OF STEADIER PRECIP. THE ATMOSPHERE WILL GRADUALLY CONTINUE TO COOL
THROUGH OVERNIGHT...WITH THE PRECIP TYPE OF FZRA/PL AT CHICAGOLAND
TAF SITES LIKELY CHANGING TO A MIX WITH SNOW IN THE FINAL COUPLE
HOURS. RFD...DPA...AND ORD ALL MAY SEE A SHORT-LIVED BOUT OF
MODERATE SNOW BEFORE THE STEADIER PRECIP ENDS. AS THE DEEP
MOISTURE DECREASES BEHIND THE SYSTEM BY 10Z...FORCING FOR PRECIP
DOES NOT COMPLETELY WANE SO THE CHANCE FOR FREEZING DRIZZLE
EXISTS. CONFIDENCE REMAINS LOW ON THIS...BUT WITH SUCH A DEEP
SATURATED LAYER AND A TURBULENT FLOW WITHIN IT...CONTINUE TO LEAN
TO THE SIDE OF CAUTION. WITHIN THE CONTINUED STRONG UPPER JET...AN
UPPER LEVEL DISTURBANCE WILL MOVE NORTHEAST OVER INDIANA THIS
AFTERNOON AND PRESENT THE CHANCE FOR LIGHT SNOW. CONFIDENCE ON
THIS IS LOW AND WILL FURTHER BE ASSESSED OVERNIGHT FOR THE 12Z
TAFS.
CIGS ARE A BIT OF A MESS OUT THERE...BUT ANTICIPATING A QUICK
LOWERING THROUGH THE NEXT COUPLE HOURS WITH LOW CONDITIONS
PERSISTING THROUGH THE MORNING. CONFIDENCE IS LOW ON EXACTLY WHEN
IMPROVEMENT TO MVFR WILL OCCUR AND THEN TO VFR.
NW WINDS WILL CONTINUE THROUGH THIS MORNING WITH SPORADIC GUSTS.
AS COLD AIR ADVECTION ENSUES A LITTLE MORE THIS AFTERNOON GUSTS
WILL LIKELY BECOME MORE PERIODIC AS THE WINDS SHIFT TO WNW.
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* LOW CONFIDENCE ON ANY MORE FZDZ.
* MEDIUM CONFIDENCE IN CIG TRENDS WITH LOW CONFIDENCE IN DURATION
OF IFR CIGS.
* MEDIUM CONFIDENCE THAT ACCUMULATING -SN WILL STAY TO THE
SOUTHEAST OF ORD AND MDW THIS AFTERNOON.
* MEDIUM CONFIDENCE IN WIND TRENDS.
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ741-LMZ742 UNTIL 10 AM SUNDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1206 AM CST SUN JAN 13 2013
.DISCUSSION...
ISSUED 853 PM CST SAT JAN 12 2013
TRICKY PRECIPITATION TYPE FORECAST TONIGHT ACROSS MUCH OF
CENTRAL/SOUTHEAST ILLINOIS FOR THE REST OF THE NIGHT. SIGNS ARE
STARTING TO POINT TO MORE OF A FREEZING RAIN PROBLEM IN MUCH OF
THE FORECAST AREA. 00Z ILX SOUNDING...AS WELL AS 00Z NAM AND
LATEST RAP SOUNDINGS...SUGGEST A MORE SIGNIFICANT ELEVATED WARM
LAYER THAN WAS PREVIOUSLY ANTICIPATED. IN ADDITION...SURFACE
TEMPERATURES ARE FALLING TO 32 DEGREES OR COLDER A LITTLE QUICKER
AS WELL. THE SURFACE FREEZING LINE CURRENTLY RESIDES IN THE
VICINITY OF THE I-55 CORRIDOR.
THIS DIFFERENCE IN THERMAL PROFILE WILL REQUIRE A FEW TWEAKS TO
THE FORECAST. THE RISK FOR APPRECIABLE SLEET APPEARS TO HAVE FADED
AS IT LOOKS LIKE THE ELEVATED WARM SHOULD COOL QUICKLY WHEN IT
DOES SO...SIGNALING A RAPID CHANGE OVER FROM RAIN/FREEZING RAIN TO
SNOW. SO...PLAN TO REMOVE MOST MENTIONS OF SLEET. THE MORE
PRONOUNCED ELEVATED WARM LAYER AND MORE RAPID SURFACE COOLING HAS
RESULTED IN FREEZING RAIN FALLING FURTHER WEST THAN ANTICIPATED
AND WILL MAKE ADJUSTMENTS TO PUSH FREEZING RAIN WEST TO THE
ILLINOIS RIVER VALLEY. FINALLY...WILL HAVE TO PUSH THE CHANGE OVER
FROM RAIN TO FREEZING RAIN EAST A BIT MORE QUICKLY.
THERE IS SOME CONCERN WITH FREEZING RAIN BECOMING MORE OF A
PREDOMINANT WEATHER TYPE THAT MORE SIGNIFICANT ICING MAY BECOME A
THREAT. HOWEVER...FEEL THAT THE RAPID END OF THE HEAVIER
PRECIPITATION...BY SHORTLY AFTER MIDNIGHT...WILL PRECLUDE THE
NEED OF AN UPGRADE TO A WARNING. THIS THREAT WILL BE WATCHED
CLOSELY.
BAK
&&
.AVIATION...
ISSUED 1206 AM CST SUN JAN 13 2013
PRECIPITATION RAPIDLY TAPERING OFF ACROSS THE CENTRAL ILLINOIS
TERMINALS. HOWEVER...PATCHY FREEZING DRIZZLE IS LIKELY TO LINGER
FOR THE REST OF THE NIGHT AND INTO THIS MORNING. ANOTHER
DISTURBANCE WILL MOVE THROUGH THE AREA LATER TODAY...BRINGING A
CHANCE OF LIGHT SNOW TO ALL TERMINALS ASIDE FROM KPIA.
PREDOMINANTLY IFR CONDITIONS ARE EXPECTED OVERNIGHT...WITH A
GRADUAL IMPROVEMENT TO MVFR OR EVEN VFR AS THE DISTURBANCE DEPARTS
LATER TODAY.
BAK
&&
.PREV DISCUSSION...
QUICK MOVING WEATHER SYSTEM TO BRING A PERIOD OF FREEZING
RAIN...SLEET AND SNOW THIS EVENING/OVERNIGHT IN ALL AREAS BUT FAR
EAST CENTRAL AND SOUTHEAST IL WHERE HEAVY RAINFALL IS A THREAT.
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
UPPER WAVE OF INTEREST BEGINNING TO EJECT NORTHEAST OUT OF THE BASE
OF THE TROF OVER THE SOUTHWEST PORTION OF THE COUNTRY WITH MODELS
ACCELERATING THE FEATURE NORTHEAST THRU THE LOWER GREAT LAKES BY
SUNDAY MORNING. THAT IS ABOUT THE ONLY SAVING GRACE WITH THE UPPER
WAVE IS THE FACT THAT IT WILL BE A QUICK MOVER...OTHERWISE WE WOULD
BE SEEING A LARGE AREA OF SIGNIFICANT ICING OVER PARTS OF CENTRAL IL
LATER TONIGHT. EVEN SO...THE NAM-WRF SOUNDINGS ARE SHOWING A MUCH
LARGER AND LONGER LASTING WARM LAYER (6-8 DEGREES DEPICTED ON THE
RAPID REFRESH MODEL AT SPI-BMI LATER THIS EVE) BETWEEN 800 AND 700 MB
THAN BEFORE...WHICH SUGGESTS THE POTENTIAL FOR LONGER DURATION OF
FREEZING RAIN AND SLEET...ESPECIALLY RIGHT UP THE I-55 CORRIDOR LATER
THIS EVENING WHERE A TENTH TO TWO TENTHS OF AN INCH MAY ACCUMULATE.
ONLY MITIGATING FACTORS WILL BE THE SPEED OF THE SYSTEM AND THAT WE
HAVE HAD A COUPLE OF DAYS WITH SURFACE TEMPS IN THE 50S...SO
INITIALLY...ROADWAYS WILL BE WET INTO THE EVENING BEFORE THE TRANSITION
OCCURS.
FURTHER WEST...ROUGHLY WEST OF THE ILLINOIS RIVER...SEEING SOME POTENTIAL
FOR SOME BRIEF MESOSCALE BANDING (NEGATIVE EPV OVER A PRONOUNCED BAND
OF FRONTOGENETICAL FORCING) OF THE PRECIP BEFORE WE LOSE OUR ICE CRYSTALS
AFTER 06Z WHICH WOULD ENHANCE THE SNOWFALL TOTALS. RIGHT NOW WE ARE
LOOKING AT 2-3 INCHES WEST OF THE ILLINOIS RIVER WITH LESSER AMOUNTS AS
YOU HEAD EAST AS SOUNDINGS INDICATE THE WARM LAYER ABOVE 800 MB HOLDS
IN PLACE UNTIL DAWN SUNDAY. BUT BY THEN...MOST FORECAST SOUNDINGS EVEN
INTO EASTERN ILLINOIS INDICATE THE LOSS OFF ICE CRYSTALS WHICH WOULD
SUGGEST THE THREAT FOR MORE FREEZING DRIZZLE OR FLURRIES...DEPENDING
ON HOW DEEP THE COLD LAYER IS IN THE LOWER LEVELS OF THE ATMOSPHERE.
A WINTER WEATHER ADVISORY WILL BE IN EFFECT STARTING EARLY THIS EVENING
WEST AND THEN ALONG THE I-57 CORRIDOR BY MIDNIGHT TO ADDRESS THE THREAT
FOR A COMBINATION OF SNOW...SLEET AND FREEZING RAIN.
ACROSS SOUTHEAST ILLINOIS...THE TRANSPORT OF MOISTURE NORTHWARD INTO
THE AREA AHEAD OF THE SYSTEM IS VERY IMPRESSIVE FOR THE SECOND WEEK
OF JANUARY WITH PRECIP WATER VALUES OF 1.50 INCHES. RAIN WITH ISOLD
THUNDERSTORMS WILL BRING AN ADDITIONAL 1-2 INCHES OF RAIN TO THE
WABASH...LITTLE WABASH AND EMBARRAS BASINS WHICH THREATENS TO BRING
THOSE BASINS TO FLOOD. AS A RESULT...WILL HAVE A FLOOD WATCH FOR OUR
FAR SOUTHEAST COUNTIES UNTIL NOON SUNDAY TO ADDRESS THE INCREASING
THREAT FOR MORE WIDESPREAD RIVER FLOODING.
AS THE WEATHER SYSTEM DEPARTS SUNDAY MORNING...LINGERING FLURRIES OR
FREEZING DRIZZLE WILL COME TO AN END. HOWEVER...MODELS INDICATE A
SECONDARY WAVE ASSOCIATED WITH A 250 MB SPEED MAX WILL PUT FAR EAST
CENTRAL AND ESPECIALLY SOUTHEAST IL IN THE RIGHT REAR QUAD OF THE
JET WHICH WILL ENHANCE THE UPWARD VERTICAL MOTION AND BRING ANOTHER
ROUND OF PRECIP SUNDAY AFTERNOON INTO EARLY EVENING. HAVE UPPED POPS
IN THAT AREA WITH FORECAST SOUNDINGS INDICATING A MESSY MIXTURE OF
SLEET...FREEZING RAIN AND SNOW FOR A BRIEF PERIOD BEFORE THE JET
SUPPORT SHIFTS AWAY FROM THE AREA BY 00Z MONDAY. AFTER THAT...QUIET
BUT COLDER WEATHER WILL PREVAIL THRU THE REMAINDER OF THE SHORT TERM
PERIOD WITH DAYTIME HIGHS IN THE 20S NORTH...TO THE LOW TO MID 30S
FAR SOUTHEAST WITH EARLY MORNING LOWS DIPPING INTO THE TEENS MOST
AREAS.
LONG TERM...WEDNESDAY THROUGH SATURDAY
COLD VORTEX OVER HUDSON BAY FORECAST BY MEDIUM RANGE MODELS TO
EVENTUALLY SHIFT SOUTH BRINGING A SURGE OF ARCTIC AIR INTO THE
GREAT LAKES REGION...BUT TIMING OF THAT OCCURRENCE IS HANDLED A
BIT DIFFERENTLY FROM WHAT WE SAW YESTERDAY WITH A SLOWER TRANSITION
TO THE COLDER PATTERN BY LATE NEXT WEEKEND.
WITH THE 500 MB UPPER LOW IN HUDSON BAY BEING THE DOMINANT WEATHER
FEATURE THIS PERIOD...MOST OF THE SIGNIFICANT WEATHER SYSTEMS WILL
TAKE A MORE SOUTHERLY TRACK WELL SOUTH OF OUR AREA DURING THIS
PERIOD WITH OUR WEATHER COMING FROM THE NORTHWEST. ANY SOUTHEAST
MOVING SHORTWAVE IN THIS FLOW PATTERN WILL BE WEAK AND MOISTURE
STARVED...AS A RESULT...WILL CONTINUE TO KEEP THE EXTENDED DRY
WITH A GRADUAL WARMING TREND AS WE HEAD INTO NEXT WEEK AS THE
CANADIAN UPPER LOW TEMPORARILY WOBBLES BACK TO THE NORTH BEFORE
HEADING SOUTH TOWARDS THE LOWER 48 JUST AFTER THIS FORECAST
PERIOD.
SHORT TERM...07
LONG TERM....SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL NOON CST TODAY FOR ILZ063-067-068-071>073.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR ILZ027>031-
036>038-040>056-061.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1141 PM CST SAT JAN 12 2013
.AVIATION...
SNOW CONTINUES TO AFFECT THE AREA...AND IS EXPECTED TO BEGIN
TAPERING OFF FROM SOUTHWEST TO NORTHEAST IN THE NEXT FEW HOURS.
KCID AND KDBQ ARE LIKELY TO SEE ANOTHER 2-4 HOURS OF LIGHT SNOW
WITH MVFR CONDITIONS. KMLI AND KBRL SHOULD SEE ANOTHER 1-2 HOURS
OF IFR VSBYS AND MVFR CIGS IN LIGHT SNOW BEFORE ALSO SWITCHING TO
MAINLY MVFR CIGS AND VSBYS WITH LIGHTER SNOW. ALL FOUR SITES SHOULD
BE BACK TO VFR BY 11Z. AN AREA OF MVFR STRATUS MAY SWING INTO THE
TERMINALS AFTER 15Z SUNDAY...WHICH SHOULD RISE INTO VFR DURING THE
EARLY AFTERNOON. CLOUDS SHOULD CLEAR OUT OF THE TERMINALS AFTER
00Z TONIGHT...BUT AS WE WILL ALREADY BE VFR NO CHANGE GROUP HAS
BEEN INCLUDED.
LE
&&
.PREV DISCUSSION... /ISSUED 933 PM CST SAT JAN 12 2013/
UPDATE...
NOW THAT WE ARE GETTING NUMEROUS REPORTS OF SNOW AND SLEET
BEGINNING ACROSS THE FORECAST AREA...A BETTER SPECIFICATION CAN BE
MADE AS TO WHERE THE SNOW/SLEET LINE CAN BE MADE. EXPECT THAT
LOCATIONS AROUND MACOMB...AND ALSO AROUND PRINCETON ARE GETTING A
WINTERY MIXTURE OF SLEET AND POSSIBLY EVEN FREEZING RAIN AS WELL.
THIS MIXTURE MAY ALSO AFFECT KEWANEE AND PORTIONS OF HENRY COUNTY...AND
EASTERN WARREN COUNTIES AS WELL IN THE NEXT FEW HOURS. WSR-88D
DUAL POL DATA IS SHOWING AREAS WHERE SLEET IS EXPECTED QUITE
NICELY THIS EVENING. HAVE MADE SOME ADJUSTMENTS TO THE FORECAST TO
REFLECT THE CURRENT TRENDS...BUT HAVE KEPT SNOWFALL AMOUNTS ABOUT
THE SAME AS BEFORE. IF THE SLEET CONTINUES FOR TOO LONG IN THE
SOUTHEAST...THE SNOWFALL FORECAST MAY NEED TO BE REDUCED IN THOSE
AREAS.
PREV DISCUSSION... /ISSUED 303 PM CST SAT JAN 12 2013/
SYNOPSIS...
COLD FRONT PUSHING INTO THE OHIO VALLEY THIS AFTERNOON...WITH COLD
AIR OOZING INTO THE UPPER MISSISSIPPI VALLEY BEHIND IT. LONG WAVE
TROUGH SPANNING THE ROCKIES...WITH ENERGY LIFTING OUT OVER THE
CENTRAL US IN FAST SOUTHWEST FLOW. LEAD SHORTWAVE GENERATING SOME
SNOW/SLEET OVER NORTHERN MO AND INTO SE IA AT THIS TIME. MAIN
PRECIP AREA ACROSS SOUTHERN MO AND SOUTHERN ILLINOIS IS ALSO
EXPANDING NORTHWARD AND IS NOW PUSHING INTO CENTRAL ILLINOIS AHEAD
OF THE MAIN SHORT WAVE...WHICH CAN BE SEEN ON SATELLITE LIFTING OUT
OF ARKANSAS.
SHORT TERM...TONIGHT AND SUNDAY...
MAIN FORECAST QUESTIONS THIS AFTERNOON CENTER AROUND DEVELOPING
PRECIPITATION EVENT FOR TONIGHT. THE INITIAL WAVE OF LIGHT SNOW/SLEET
NOW MOVING ACROSS EASTERN IA WILL HELP COOL AND SATURATE THE COLUMN
AHEAD OF TONIGHTS WAVE BUT WILL HAVE LITTLE OTHER IMPACT. FOR TONIGHT...OF
THE SHORT RANGE MODELS...THE RAP IS THE MOST AGGRESSIVE WITH
SNOWFALL AMOUNTS...SUGGESTING 4 TO 6 INCHES ALONG AND EAST OF THE
MISSISSIPPI RIVER. MEANWHILE...THE NAM...GFS...AND ECMWF ARE MORE
CONSERVATIVE WITH 2-3 INCHES AT MOST. THUS WILL FAVOR A BLEND OF
THE NAM AND ECMWF FOR THIS FORECAST...ESPECIALLY FOR MOISTURE PARAMETERS.
THERE IS CONSISTENCY IN THE FORECAST SOUNDINGS...SHOWING A LARGE
WEDGE OF WARM AIR ALOFT...ESPECIALLY EAST OF THE MISSISSIPPI
RIVER...THAT WILL HAVE TO COOL BEFORE PRECIP CHANGES TO SNOW.
CURRENT THINKING IS THAT NEAR THE RIVER THE PERIOD OF SLEET SHOULD
BE BRIEF...BUT WILL LAST LONGER AS YOU GO EAST. BUREAU/PUTNAM
COUNTIES COULD SEE A COUPLE OF HOURS OF SLEET BEFORE IT CHANGES TO
SNOW BY MIDNIGHT. IT IS ALSO NOT OUT OF THE QUESTION FOR A BRIEF
PERIOD OF FREEZING RAIN TO FALL AT ONSET IN THE BUREAU/PUTNAM
COUNTY AREA. HOWEVER...IF THIS WOULD OCCUR...THE EVAPORATIVE
COOLING WOULD QUICKLY CHANGE IT TO SLEET. AND WITH THE WARM
TEMPERATURES THESE LAST FEW DAYS...ONLY ELEVATED SURFACES SHOULD
BE AT RISK FOR FREEZING.
IN TERMS OF SNOW AMOUNTS...THE GARCIA METHOD WOULD SUGGEST 2-4 INCHES
IN THE HEAVIEST BAND FROM THE QUAD CITIES NORTHEASTWARD. THE MODEL TIME
SECTIONS DO SUPPORT THIS...SHOWING POTENTIAL FOR DENDRITIC GROWTH
IN THAT SAME AREA. WHILE DENDRITES WOULD INCREASE AMOUNTS...THE SHORT
DURATION OF THE EVENT AND ANY SLEET AT ONSET WILL LIMIT THE
ACCUMULATIONS.
THE BOTTOM LINE IS THAT I EXPECT A SHARP CUT-OFF IN SNOW ACCUMULATIONS
SOMEWHERE IN THE VICINITY OF THE 380 CORRIDOR...THE HEAVIEST SNOW
AMOUNTS IN THE 2-4 INCH RANGE FROM NEAR THE QUAD CITIES NORTHEASTWARD
TO FREEPORT...AND A LONGER PERIOD OF SLEET WITH LESSER SNOW
ACCUMULATIONS AS YOU MOVE TOWARD THE PRINCETON ILLINOIS AREA. THE
MAIN PRECIP EVENT WILL BEGIN AFTER 6 PM TONIGHT...CHANGING TO SNOW
AREA WIDE BY MIDNIGHT AND SHOULD HAVE EXITED ALL BUT THE EXTREME
EASTERN PORTIONS OF THE CWFA BY 6 AM.
DMD
LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...
SUNDAY NIGHT AND MONDAY...LATEST 12Z RUN MODELS IN GOOD AGREEMENT OF
SUGGESTING SFC RIDGING SLIDING ACRS THE REGION FROM THE WEST SUNDAY
NIGHT...WHILE CONFLUENT FLOW REGION WEST OF L/W TROF TRYING TO
PHASE ACRS THE EASTERN ROCKIES. EXPECT CLEARING SKIES AS HIGH CLOUDS
NORTHWEST OF LLVL BAROCLINIC REGION PUSH EASTWARD...COMBINED WITH
DECREASING WINDS FOR A COLD NIGHT OVER FRESH SNOW COVER. SOME SINGLE
DIGITS POSSIBLE BY EARLY MON MORNING. MAINLY CLEAR SKIES AND COLD
CONDITIONS TO FINISH OUT THE PERIOD WITH HIGHS IN THE 20S MON AND
SINGLE DIGITS TO LOWER TEENS MON NIGHT. SOME LIGHT RETURN FLOW MAY
MAKE FOR NON-DIURNAL TEMP TRENDS PRE-DAWN EARLY TUE MORNING WEST OF
THE MS RVR.
TUESDAY AND WEDNESDAY...LATEST RUN MEDIUM RANGE SOLUTIONS SUGGEST
THE ABOVE MENTIONED LONG WAVE TROF AXIS WILL SHEAR ACRS THE MID
CONUS THIS PERIOD FROM THE GRT LKS...ALL THE WAY TO THE BAJA OF MEX.
UPPER RIDGE ALONG AND JUST OFF THE WEST COAST AMPLIFIES...EVENTUALLY
DUMPING RIDGE-RIDING WAVE ENERGY DOWN ACRS THE UPPER MIDWEST AND GRT
LKS THROUGH MID WEEK. HOW FAR SOUTH THIS CLIPPER TYPE WAVE WILL
EVENTUALLY DIG IS STILL SOMEWHAT UNCERTAIN...ALL LONGER RANGE MODEL
SOLUTIONS BUT THE 12Z GFS KEEP LEAD WAVE AND IT/S ASSOCIATED PRECIP
TO THE NORTH OF THE AREA UNTIL MAYBE WED NIGHT WHEN SOME FLURRIES
MAKE IT ACRS THE NORTHEASTERN THIRD OF THE AREA/CWA UNDER RE-
ENFORCING CYCLONIC FLOW DIGGING ACRS THE SOUTHWESTERN GRT LKS. THE
12Z GFS IS MORE PROGRESSIVE AND DEEPER SOUTH WITH THE CLIPPER AND
PRODUCES LIGHT SNOW ACRS MOST OF THE LOCAL AREA TUE NIGHT INTO WED
MORNING BEFORE SHUTTLING QUICKLY OFF TO THE EAST. FOR NOW WILL SIDE
WITH THE MAJORITY AND KEEP THE FCST DRY...WITH THERMAL MODERATION
FROM THE SOUTHWEST AHEAD OF THE NORTHERN STREAM CLIPPER. HIGHS TUE
NEAR 30...MAY TRANSLATE INTO THE 30S BY WED BEFORE COLD FRONT OFF
THE PASSING CLIPPER SYSTEM TO THE NORTH SWEEPS THROUGH THE CWA BY
LATE WED.
THURSDAY THROUGH SATURDAY...LATEST RUN MEDIUM RANGE MODEL SOLUTIONS
AND ENSEMBLES GENERALLY SUGGEST WHILE A TYPE OF REX BLOCK SETS UP
ACRS THE WEST COAST AND SOUTHWESTERN U.S...BROAD UPPER LEVEL
TROFFINESS SETS UP ACRS MUCH OF THE EASTERN CONUS SOUTH OF NORTHERN
HUDSON BAY POLAR VORTEX. A RIBBON OF LLVL BAROCLINICITY SETS UP
PARALLEL TO THIS FEATURE FROM SOUTH CENTRAL CANADA...TO THE MID
ATLANTIC WHILE A BUILDING DOME OF VERY COLD AIRMASS LOOMS ACRS THE
EASTERN TWO THIRDS OF CANADA. WHILE THE REAL COLD AIR REMAINS BOTTLED
UP BY THIS PATTERN...WILL CONTINUE TO ADVERTISE MODERATING TEMPS
THROUGH SAT. DRY CONDITIONS TOO AS ANY IMPULSES WILL LOOK TO RIPPLE
ALONG THE BAROCLINIC RIBBON AND PRODUCE PRECIP MAINLY OT THE NORTH
ACRS THE DAKOTAS...MN...WI AND THE NORTH HALF OF THE GRT LKS INTO
SAT NIGHT. SOME LONGER RANGE SIGNS OF PLUNGING JET ENERGY TO ALLOW
SOME OF THE ARCTIC AIR TO BREAK LOOSE AND SPILL ACRS THE WESTERN
GRT LKS BY EARLY NEXT WEEK. ..12..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR CLINTON-DES
MOINES-JACKSON-LEE-LOUISA-MUSCATINE-SCOTT.
IL...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR BUREAU-CARROLL-
HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-MERCER-
PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE.
MO...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR CLARK.
&&
$$
LE
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1128 PM CST SAT JAN 12 2013
...UPDATED AVIATION DISCUSSION...
.UPDATE...
/1051 PM CST Sat Jan 12 2013/
Was initially concerned with light freezing drizzle from Clinton to
Boonville per RAP forecast soundings. However the feeling is it
should have began to materialize by now and it isn`t. Additionally
RAP soundings show a loss of saturation in the lower levels after 06z
so it would appear we missed the window. As a result have cancelled
the advisory for the entire CWA. It would appear the earlier snow
produced 2-3 inches generally south of I 70 and from Miami and Linn
Counties eastward...missing most of the KC Metro.
Bailey
&&
.UPDATE...
/714 PM CST Sat Jan 12 2013/
After intense late afternoon and early evening snow, it has really
diminished rapidly over most of the CWA. Snowfall reports have ranged
from 1-3 inches across the affected areas, with some locations...most
notably along the 50 hwy corridor reporting sporadic sleet and
freezing rain at the onset of precipitation before changing to all
snow. Rapid precip ending could be due in part to large area of dry
air to the west working in. HRRR has pegged this pretty good, and
even it has underestimated the decrease in precipitation to some
degree. As a result I have cancelled much of the western and northern
portions of the winter weather advisory, and will likely need to
cancel the rest of the advisory later this evening as the last of the
snow winds down.
Bailey
&&
.DISCUSSION...
Near Term (Through Tonight)...
Recent water vapor imagery shows a deepening positive tilt shortwave
trough ejecting across the TX/OK panhandle region, with an extensive
Pacific moist plume spreading northward from eastern Texas into the
Mid Mississippi valley region. Large scale ascent was rapidly
increasing within a broad area bound between the surface cold front
across central Arkansas and the trailing sloping frontal region that
extends back into SE Kansas through NE Missouri.
12Z upper air soundings showed a number of potential problems with
the near term forecast:
1.) Extensive dry air present both above and below the frontogenetic
region.
2.) A layer of 0 to +2C air lingering across the southern CWA
3.) Weak static stability (-EPV) present just above the mid level
frontogenesis region -- albeit in increasingly dry air.
Since 19Z, blossoming of echos on regional radar imagery confirms
large scale ascent associated with a 300mb jet streak was beginning
to overspread eastern KS/OK into MO/AR. Precipitation has been
largely showery in nature and has had difficulty reaching the ground
in the local CWA. Most of the initial virga sublimation will likely
aid in rapid top down saturation over the next 1-3 hours. Light snow
and sleet have been reported from the NWS office southward and this
is likely the beginning of tonight`s event. In the absence of
significant cold advection, diabatic cooling will likely be the
primary driving mechanism to eliminate the lingering warm nose, with
any PL over the far srn CWA going to all snow.
For this evening, 12Z models still indicate a rather strong coupling
between 850-600mb sloped frontogenesis and the upper jet streak.
Three big questions remain with this evening`s forecast. One being
the character of the snow, as stability parameters indicate we may
see elongated banding and a lack of uniformity. The second is the
primary moist axis feeding from srn Texas into AR and southern MO
which could perhaps drive more efficient precipitation south and
east of the local region. Lastly, the primary forcing occurs in
temperatures much warmer (-4 to -8C) than dendrite preference which
would reduce overall accumulations. With that said, the 1-3" painted
looks right on target with my analysis, with I-35 very near the
western bound of where frontogenetic forcing drops off rapidly.
Bottom line is that although this is a nuisance snow, amounts could
still vary quite a bit from locale to locale within that 1-3"
spectrum, and would not be surprised to see a slight buffer either
side of that range within the advisory area. Snow should taper off
quickly west to east after midnight as the subsidence overspreads
the area in the wake of the jet streak.
Bookbinder
Short Term (Sunday through Monday Night)...
Skies will clear from west to east on Sunday, with temperatures
really the only issue of concern through Monday Night. Readings will
largely be dictated by the axis of incoming high pressure and the
extent of snow cover once cold advection ceases by Monday morning.
Didn`t see any reason to stray too far from previous forecast.
Bookbinder
Medium Range (Tuesday through Saturday)...
A weakening, strongly tilted trough will gradually push east and
become enveloped by the northern jet stream toward the beginning of
the period, allowing the overall pattern to transition to a warmer,
more zonal flow across the central U.S. by the middle of next week.
Temperatures could still be a bit cool on Tuesday as the trough
departs, with most models indicating a lingering pocket of 850 mb
temperatures in the -7 to -9 degree range over northern Missouri. By
Wednesday, temperatures should rise to near or slightly above normal
values, with highs likely in the upper 30`s to mid 40`s for
Wednesday through Saturday. There remains a small possibility for
temperatures to be significantly colder on Thursday and Friday as
the trough over eastern Canada deepens, potentially allowing some
very cold air to filter into eastern portions of the CWA. This was
indicated yesterday by the EC and today by the GEM, but still
remains an outlying solution.
Precipitation is not expected through this period, with surface high
pressure generally dominating the central Plains and the jet stream
remaining well to the north.
Laflin
&&
.AVIATION...
For the 06Z TAFs...VFR conditions expected during this forecast
period. Will see mid clouds through mid Sunday morning over west
central MO until an upper level jet streak passes by. Otherwise, nw
winds around 10kts, a little higher at KSTJ, through Sunday
afternoon, then weaken as high pressure center moves in.
MJ
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1057 PM CST Sat Jan 12 2013
.UPDATE...
/1051 PM CST Sat Jan 12 2013/
Was initially concerned with light freezing drizzle from Clinton to
Boonville per RAP forecast soundings. However the feeling is it
should have began to materialize by now and it isn`t. Additionally
RAP soundings show a loss of saturation in the lower levels after 06z
so it would appear we missed the window. As a result have cancelled
the advisory for the entire CWA. It would appear the earlier snow
produced 2-3 inches generally south of I 70 and from Miami and Linn
Counties eastward...missing most of the KC Metro.
/714 PM CST Sat Jan 12 2013/
After intense late afternoon and early evening snow, it has really
diminished rapidly over most of the CWA. Snowfall reports have ranged
from 1-3 inches across the affected areas, with some locations...most
notably along the 50 hwy corridor reporting sporadic sleet and
freezing rain at the onset of precipitation before changing to all
snow. Rapid precip ending could be due in part to large area of dry
air to the west working in. HRRR has pegged this pretty good, and
even it has underestimated the decrease in precipitation to some
degree. As a result I have cancelled much of the western and northern
portions of the winter weather advisory, and will likely need to
cancel the rest of the advisory later this evening as the last of the
snow winds down.
Bailey
&&
.DISCUSSION...
Near Term (Through Tonight)...
Recent water vapor imagery shows a deepening positive tilt shortwave
trough ejecting across the TX/OK panhandle region, with an extensive
Pacific moist plume spreading northward from eastern Texas into the
Mid Mississippi valley region. Large scale ascent was rapidly
increasing within a broad area bound between the surface cold front
across central Arkansas and the trailing sloping frontal region that
extends back into SE Kansas through NE Missouri.
12Z upper air soundings showed a number of potential problems with
the near term forecast:
1.) Extensive dry air present both above and below the frontogenetic
region.
2.) A layer of 0 to +2C air lingering across the southern CWA
3.) Weak static stability (-EPV) present just above the mid level
frontogenesis region -- albeit in increasingly dry air.
Since 19Z, blossoming of echos on regional radar imagery confirms
large scale ascent associated with a 300mb jet streak was beginning
to overspread eastern KS/OK into MO/AR. Precipitation has been
largely showery in nature and has had difficulty reaching the ground
in the local CWA. Most of the initial virga sublimation will likely
aid in rapid top down saturation over the next 1-3 hours. Light snow
and sleet have been reported from the NWS office southward and this
is likely the beginning of tonight`s event. In the absence of
significant cold advection, diabatic cooling will likely be the
primary driving mechanism to eliminate the lingering warm nose, with
any PL over the far srn CWA going to all snow.
For this evening, 12Z models still indicate a rather strong coupling
between 850-600mb sloped frontogenesis and the upper jet streak.
Three big questions remain with this evening`s forecast. One being
the character of the snow, as stability parameters indicate we may
see elongated banding and a lack of uniformity. The second is the
primary moist axis feeding from srn Texas into AR and southern MO
which could perhaps drive more efficient precipitation south and
east of the local region. Lastly, the primary forcing occurs in
temperatures much warmer (-4 to -8C) than dendrite preference which
would reduce overall accumulations. With that said, the 1-3" painted
looks right on target with my analysis, with I-35 very near the
western bound of where frontogenetic forcing drops off rapidly.
Bottom line is that although this is a nuisance snow, amounts could
still vary quite a bit from locale to locale within that 1-3"
spectrum, and would not be surprised to see a slight buffer either
side of that range within the advisory area. Snow should taper off
quickly west to east after midnight as the subsidence overspreads
the area in the wake of the jet streak.
Bookbinder
Short Term (Sunday through Monday Night)...
Skies will clear from west to east on Sunday, with temperatures
really the only issue of concern through Monday Night. Readings will
largely be dictated by the axis of incoming high pressure and the
extent of snow cover once cold advection ceases by Monday morning.
Didn`t see any reason to stray too far from previous forecast.
Bookbinder
Medium Range (Tuesday through Saturday)...
A weakening, strongly tilted trough will gradually push east and
become enveloped by the northern jet stream toward the beginning of
the period, allowing the overall pattern to transition to a warmer,
more zonal flow across the central U.S. by the middle of next week.
Temperatures could still be a bit cool on Tuesday as the trough
departs, with most models indicating a lingering pocket of 850 mb
temperatures in the -7 to -9 degree range over northern Missouri. By
Wednesday, temperatures should rise to near or slightly above normal
values, with highs likely in the upper 30`s to mid 40`s for
Wednesday through Saturday. There remains a small possibility for
temperatures to be significantly colder on Thursday and Friday as
the trough over eastern Canada deepens, potentially allowing some
very cold air to filter into eastern portions of the CWA. This was
indicated yesterday by the EC and today by the GEM, but still
remains an outlying solution.
Precipitation is not expected through this period, with surface high
pressure generally dominating the central Plains and the jet stream
remaining well to the north.
Laflin
&&
.AVIATION...
For the 18Z TAFs, recent model guidance still suggests the bulk of
this evening`s winter weather event will likely skate just east of
the terminals with MKC seeings the greatest impacts of some
accumulating snow. A significant layer of dry air both above and
below a narrow corridor of strong elevated frontogenesis is the main
prohibiting factor.
VFR conditions will continue through 00Z with gradually lowering mid
cloud. Ceilings should steadily fall thereafter.
Basically have kept STJ dry, MCI on the fringe with MVFR to perhaps
brief IFR conditions this evening, and MKC in the steadier snow this
evening with IFR conditions likely. Conditions should rapidly
improve after around 07Z.
Winds will remain northwest to north-northwest at around 10 knots.
Bookbinder
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1135 PM CST SAT JAN 12 2013
.DISCUSSION...LATEST FOG STRATUS IMAGERY LOOP SHOWS AN AREA OF
925MB-850MB MOISTURE/CLOUDS/ISOLATED FLURRIES IN FAR SOUTH CENTRAL
SASKATCHEWAN AND MANITOBA. THE RUC13 HAS THIS HANDLED THE BEST AND
WILL FOLLOW. LINEAR EXTRAPOLATION/TIMING BRINGS THE CLOUDS/ISOLATED
FLURRIES INTO CROSBY BY 09Z SUNDAY AND CONTINUES TO PUSH SOUTHEAST
INTO SOUTH CENTRAL NORTH DAKOTA BY MID MORNING SUNDAY. THUS HAVE
BUMPED THE SKY GRIDS UP TO REFLECT THE BKN/OVC CONDITIONS ALONG
WITH ISOLATED FLURRIES SPREADING FROM NORTHWEST TO SOUTHEAST
OVERNIGHT INTO SUNDAY MORNING. THIS WILL LIKELY HAVE AN IMPACT ON
THE CURRENT WIND CHILL ADVISORY ACROSS THE NORTH LATER TONIGHT AS
CURRENT WIND CHILL TEMPERATURES ASSOCIATED WITH THE CLOUD DECK IN
SASKATCHEWAN ARE GENERALLY RANGING BETWEEN 10 AND 15 BELOW ZERO.
ELSEWHERE THE WIND CHILL ADVISORY SHOULD HOLD UNTIL ABOUT 15Z SUNDAY
BEFORE THE CLOUDS GET INTO SOUTH CENTRAL NORTH DAKOTA. WILL CONTINUE
TO MONITOR THIS OVERNIGHT.
OTHERWISE...WATER VAPOR SHOWING A SHORTWAVE TROUGH DROPPING SOUTHEAST
FROM NORTHERN ALBERTA. NO SURFACE REFLECTION WITH THIS SHORTWAVE
AS IT IS FORECAST TO MOVE NEAR GLASGOW BY 00Z MONDAY. OVERALL FORECAST
IS ON TRACK AND MINIMAL CHANGES TO REST OF SENSIBLE WEATHER ELEMENTS.
&&
.AVIATION...VFR CONDITIONS WILL PREVAIL ACROSS WESTERN AND CENTRAL
NORTH DAKOTA THROUGH SUNDAY MORNING. A BAND OF VFR CIGS WILL MOVE
NORTHWEST TO SOUTHEAST ACROSS WESTERN AND CENTRAL NORTH DAKOTA
SUNDAY MORNING. MVFR CIGS MAY THEN DEVELOP NORTH (KISN/KMOT) SUNDAY
AFTERNOON AND ALONG THE I-94 CORRIDOR AFTER SUNSET SUNDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL NOON CST SUNDAY FOR NDZ001>005-009>013-
017>023-025-035>037.
&&
$$
DISCUSSION...KS
AVIATION...TM
AREA FORECAST DISCUSSION
NWS NORMAN OK
1036 PM CST SAT JAN 12 2013
.DISCUSSION...
06Z AVIATION DISCUSSION FOLLOWS....
&&
.AVIATION...
A HARD-TO-SEE WAVE IN STRONG SW FLOW ALOFT APPEARS TO BE THE
CAUSE OF THE REMAINING SIGNIFICANT RADAR ECHOES AT THIS TIME. MOST
OF THE ECHOES PORTRAY VIRGA...BUT THERE IS REASON TO BELIEVE THAT
SOME OF THE PRECIPITATION NEAR KSPS IS REACHING THE
GROUND...PROBABLY AS -SN. THERE IS A SLIGHT CHANCE THAT THIS SNOW
MAY REACH OTHER TAF SITES TO THE N AND NE...BUT THE CHANCES ARE
CURRENTLY TOO LOW TO MENTION IN THE TAFS. BY ISSUANCE TIME...WE
HOPE TO HAVE A CLEARER RADAR TREND AND MAY MODIFY THE CURRENT
EXPECTATIONS. OTHERWISE...GENERALLY VFR CONDITIONS AND VERY
GRADUALLY DIMINISHING N WINDS ARE EXPECTED THROUGH THE PERIOD.
&&
.PREV DISCUSSION... /ISSUED 1007 PM CST SAT JAN 12 2013/
UPDATE...
CANCELLED REMAINING WINTER WEATHER ADVISORY...
DISCUSSION...
DECIDED TO CANCEL THE REMAINING WINTER WEATHER ADVISORY FOR THE
COUNTIES IN NORTHWESTERN AND CENTRAL OKLAHOMA. SURFACE ANALYSIS
CONTINUES TO SHOW VERY COLD DRY AIR AT THE SURFACE FUNNELING
ACROSS THE REGION BEHIND THE LINE OF WINTRY PRECIPITATION...WHICH
CONTINUES TO MOVE ACROSS EASTERN OKLAHOMA. 00Z SOUNDING FROM OUN
REVEALED A MOIST LAYER BETWEEN APPROXIMATELY 700MB AND 900MB.
HOWEVER...ISENTROPIC ANALYSIS AT 295K ON THE LATEST RAP AND NAM
CONTINUE TO SHOW VERY LITTLE LIFT AVAILABLE WITHIN THIS MOIST
LAYER.
SOME RESIDUAL LIGHT SNOW/FLURRIES AND POSSIBLY FREEZING DRIZZLE
MAY EXIST THROUGH MIDNIGHT ACROSS THE REGION...HOWEVER MOST
LOCATIONS WILL LIKELY STAY DRY.
ELSEWHERE ACROSS THE FORECAST AREA...A NARROW BAND OF LIGHT
SNOW/FREEZING RAIN HAS DEVELOPED JUST EAST OF WICHITA FALLS TEXAS
THROUGH 03Z. A SLIGHT SHEAR AXIS ACROSS THE AREA HAS PROVIDED JUST
ENOUGH ISENTROPIC LIFT WITHIN THE LOW LEVELS TO DEVELOP SOME
PRECIP. A THE MOMENT...DO NOT EXPECT THIS LINE TO PROGRESS VERY
FAR NORTH...AS VERY DRY AIR CONTINUES TO ADVANCE SOUTHWARD AT THE
SURFACE. HOWEVER...SOME ROADWAYS ACROSS WESTERN NORTH TEXAS MAY SE
SOME SLICK SPOTS.
HAZARDOUS TRAVEL CONDITIONS WILL PERSIST OVERNIGHT AT LOCATIONS
IMPACTED BY WINTER PRECIP THIS EVENING AS TEMPERATURES DROP WELL
BELOW FREEZING INTO THE TEENS AND 20S. IF YOU MUST TRAVEL...PLEASE
USE EXTREME CAUTION...CHECK WITH THE DEPARTMENT OF TRANSPORTATION
IN BOTH OKLAHOMA AND TEXAS FOR CONDITIONS...AND REMEMBER TO SLOW
DOWN...GIVE PLENTY OF ROOM...AND TAKE YOUR TIME.
JTK
PREV DISCUSSION... /ISSUED 533 PM CST SAT JAN 12 2013/
DISCUSSION...
00Z AVIATION DISCUSSION FOLLOWS....
AVIATION...
RADAR SHOWS A BAND OF +SN IN FAR NW OK...WHICH IS AFFECTING KGAG
AND KWWR. THIS SNOW SHOULD DIMINISH WITHIN A FEW HOURS...WHILE LOW
CLOUDS REMAIN AND ADVANCE S TOWARD KCSM LATER TONIGHT. IN
ADDITION...RA...FZRA...AND PL EXTENDS FROM KADM TO KTUL. WHILE
THIS BAND IS NOT EXPECTED TO AFFECT OUR TAF SITES...MODELS SEEM
FAIRLY CONFIDENT THAT ANOTHER BAND OF FZRA WILL FORM FARTHER WEST
BETWEEN 00Z AND 04Z OR SO. GIVEN MODEL PERFORMANCE LATELY...THIS
IS FAR FROM DEFINITE...BUT IS LIKELY ENOUGH TO INCLUDE IN TAFS. AS
THE SURFACE FRONT MOVES FARTHER AWAY...AND HIGH PRESSURE BEGINS TO
TAKE FIRMER CONTROL OF THE REGION...GRADUAL IMPROVEMENT IS
EXPECTED TOMORROW. THE TIMES IN THE TAFS...ESPECIALLY REGARDING
IMPROVEMENT TOMORROW...SHOULD BE TAKEN AS ROUGH ESTIMATES.
PREV DISCUSSION... /ISSUED 307 PM CST SAT JAN 12 2013/
DISCUSSION...
PRECIPITATION IS INCREASING IN A FEW AREAS... SHOWERS AND STORMS
EAST... A WINTRY MIX SOUTH CENTRAL.. CENTRAL AND NORTH CENTRAL
OKLAHOMA... AND VIRGA/SNOW WEST. LOW LEVEL TEMPERATURES WILL COOL
AS PRECIPITATION MOISTENS LOWER LAYERS AND TEMPERATURES APPROACH
WET BULB. THIS WILL BRING THE TEMPERATURE DOWN TO NEAR OR BELOW
FREEZING IN MANY AREAS. MEANWHILE... MID LEVELS ARE DRYING AS
SHORTWAVE MOVES THROUGH THE AREA AS SEEN ON WATER VAPOR LOOP. IN
TIME... THIS WILL REMOVE HIGH RH FROM THE DENDRITIC GROWTH ZONE
TEMPERATURE RANGE USHERING IN A TREND MORE TOWARD FREEZING RAIN
AND FREEZING DRIZZLE. SO ALTHOUGH PRECIPITATION AMOUNTS WILL
GENERALLY BE LIGHT... THE FORECAST OF FREEZING RAIN/FREEZING
DRIZZLE MAY STILL CAUSE ISSUES INTO THE EVENING HOURS ACROSS
CENTRAL AND NORTH CENTRAL OKLAHOMA... SO WILL LEAVE THE WINTER
WEATHER ADVISORY UP. DID NOT GET TOO TRICKY WITH THE PRECIPITATION
TYPES IN THE PACKAGE... KEEPING IT SNOW NORTHWEST... RAIN
SOUTHEAST WHERE TEMPERATURES WILL REMAIN ABOVE FREEZING FOR A
WHILE... AND FREEZING RAIN/SNOW/SLEET IN BETWEEN THESE AREAS.
NAM ALSO SHOWS LOW-LEVEL LIFT REDEVELOPING IN THE 06Z-14Z TIME
FRAME... ESPECIALLY IN THE SOUTHWEST. IF THIS VERIFIES... FREEZING
DRIZZLE WILL BE A POSSIBILITY AFTER MIDNIGHT THROUGH A LITTLE
AFTER SUNRISE. WILL KEEP A SLIGHT CHANCE OF FREEZING DRIZZLE AFTER
MIDNIGHT AND WILL HAVE THE NEXT SHIFTS CONTINUE TO MONITOR THE
TRENDS.
WITH WINTER WEATHER IN THE FIRST PERIOD BEING THE MAJOR WEATHER
IMPACT FOR THIS FORECAST CYCLE... ONLY MADE MINOR ADJUSTMENTS TO
THE FORECAST IN THE LATER PERIODS.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 21 32 17 37 / 50 10 10 10
HOBART OK 18 35 13 36 / 10 0 0 0
WICHITA FALLS TX 24 40 18 40 / 20 10 10 10
GAGE OK 11 30 7 32 / 40 0 0 0
PONCA CITY OK 16 30 10 35 / 70 10 10 10
DURANT OK 28 40 21 43 / 30 10 10 10
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
04/23/23
AREA FORECAST DISCUSSION
NWS NORMAN OK
1007 PM CST SAT JAN 12 2013
.UPDATE...
CANCELLED REMAINING WINTER WEATHER ADVISORY...
&&
.DISCUSSION...
DECIDED TO CANCEL THE REMAINING WINTER WEATHER ADVISORY FOR THE
COUNTIES IN NORTHWESTERN AND CENTRAL OKLAHOMA. SURFACE ANALYSIS
CONTINUES TO SHOW VERY COLD DRY AIR AT THE SURFACE FUNNELING
ACROSS THE REGION BEHIND THE LINE OF WINTRY PRECIPITATION...WHICH
CONTINUES TO MOVE ACROSS EASTERN OKLAHOMA. 00Z SOUNDING FROM OUN
REVEALED A MOIST LAYER BETWEEN APPROXIMATELY 700MB AND 900MB.
HOWEVER...ISENTROPIC ANALYSIS AT 295K ON THE LATEST RAP AND NAM
CONTINUE TO SHOW VERY LITTLE LIFT AVAILABLE WITHIN THIS MOIST
LAYER.
SOME RESIDUAL LIGHT SNOW/FLURRIES AND POSSIBLY FREEZING DRIZZLE
MAY EXIST THROUGH MIDNIGHT ACROSS THE REGION...HOWEVER MOST
LOCATIONS WILL LIKELY STAY DRY.
ELSEWHERE ACROSS THE FORECAST AREA...A NARROW BAND OF LIGHT
SNOW/FREEZING RAIN HAS DEVELOPED JUST EAST OF WICHITA FALLS TEXAS
THROUGH 03Z. A SLIGHT SHEAR AXIS ACROSS THE AREA HAS PROVIDED JUST
ENOUGH ISENTROPIC LIFT WITHIN THE LOW LEVELS TO DEVELOP SOME
PRECIP. A THE MOMENT...DO NOT EXPECT THIS LINE TO PROGRESS VERY
FAR NORTH...AS VERY DRY AIR CONTINUES TO ADVANCE SOUTHWARD AT THE
SURFACE. HOWEVER...SOME ROADWAYS ACROSS WESTERN NORTH TEXAS MAY SE
SOME SLICK SPOTS.
HAZARDOUS TRAVEL CONDITIONS WILL PERSIST OVERNIGHT AT LOCATIONS
IMPACTED BY WINTER PRECIP THIS EVENING AS TEMPERATURES DROP WELL
BELOW FREEZING INTO THE TEENS AND 20S. IF YOU MUST TRAVEL...PLEASE
USE EXTREME CAUTION...CHECK WITH THE DEPARTMENT OF TRANSPORTATION
IN BOTH OKLAHOMA AND TEXAS FOR CONDITIONS...AND REMEMBER TO SLOW
DOWN...GIVE PLENTY OF ROOM...AND TAKE YOUR TIME.
JTK
&&
.PREV DISCUSSION... /ISSUED 533 PM CST SAT JAN 12 2013/
DISCUSSION...
00Z AVIATION DISCUSSION FOLLOWS....
AVIATION...
RADAR SHOWS A BAND OF +SN IN FAR NW OK...WHICH IS AFFECTING KGAG
AND KWWR. THIS SNOW SHOULD DIMINISH WITHIN A FEW HOURS...WHILE LOW
CLOUDS REMAIN AND ADVANCE S TOWARD KCSM LATER TONIGHT. IN
ADDITION...RA...FZRA...AND PL EXTENDS FROM KADM TO KTUL. WHILE
THIS BAND IS NOT EXPECTED TO AFFECT OUR TAF SITES...MODELS SEEM
FAIRLY CONFIDENT THAT ANOTHER BAND OF FZRA WILL FORM FARTHER WEST
BETWEEN 00Z AND 04Z OR SO. GIVEN MODEL PERFORMANCE LATELY...THIS
IS FAR FROM DEFINITE...BUT IS LIKELY ENOUGH TO INCLUDE IN TAFS. AS
THE SURFACE FRONT MOVES FARTHER AWAY...AND HIGH PRESSURE BEGINS TO
TAKE FIRMER CONTROL OF THE REGION...GRADUAL IMPROVEMENT IS
EXPECTED TOMORROW. THE TIMES IN THE TAFS...ESPECIALLY REGARDING
IMPROVEMENT TOMORROW...SHOULD BE TAKEN AS ROUGH ESTIMATES.
PREV DISCUSSION... /ISSUED 307 PM CST SAT JAN 12 2013/
DISCUSSION...
PRECIPITATION IS INCREASING IN A FEW AREAS... SHOWERS AND STORMS
EAST... A WINTRY MIX SOUTH CENTRAL.. CENTRAL AND NORTH CENTRAL
OKLAHOMA... AND VIRGA/SNOW WEST. LOW LEVEL TEMPERATURES WILL COOL
AS PRECIPITATION MOISTENS LOWER LAYERS AND TEMPERATURES APPROACH
WET BULB. THIS WILL BRING THE TEMPERATURE DOWN TO NEAR OR BELOW
FREEZING IN MANY AREAS. MEANWHILE... MID LEVELS ARE DRYING AS
SHORTWAVE MOVES THROUGH THE AREA AS SEEN ON WATER VAPOR LOOP. IN
TIME... THIS WILL REMOVE HIGH RH FROM THE DENDRITIC GROWTH ZONE
TEMPERATURE RANGE USHERING IN A TREND MORE TOWARD FREEZING RAIN
AND FREEZING DRIZZLE. SO ALTHOUGH PRECIPITATION AMOUNTS WILL
GENERALLY BE LIGHT... THE FORECAST OF FREEZING RAIN/FREEZING
DRIZZLE MAY STILL CAUSE ISSUES INTO THE EVENING HOURS ACROSS
CENTRAL AND NORTH CENTRAL OKLAHOMA... SO WILL LEAVE THE WINTER
WEATHER ADVISORY UP. DID NOT GET TOO TRICKY WITH THE PRECIPITATION
TYPES IN THE PACKAGE... KEEPING IT SNOW NORTHWEST... RAIN
SOUTHEAST WHERE TEMPERATURES WILL REMAIN ABOVE FREEZING FOR A
WHILE... AND FREEZING RAIN/SNOW/SLEET IN BETWEEN THESE AREAS.
NAM ALSO SHOWS LOW-LEVEL LIFT REDEVELOPING IN THE 06Z-14Z TIME
FRAME... ESPECIALLY IN THE SOUTHWEST. IF THIS VERIFIES... FREEZING
DRIZZLE WILL BE A POSSIBILITY AFTER MIDNIGHT THROUGH A LITTLE
AFTER SUNRISE. WILL KEEP A SLIGHT CHANCE OF FREEZING DRIZZLE AFTER
MIDNIGHT AND WILL HAVE THE NEXT SHIFTS CONTINUE TO MONITOR THE
TRENDS.
WITH WINTER WEATHER IN THE FIRST PERIOD BEING THE MAJOR WEATHER
IMPACT FOR THIS FORECAST CYCLE... ONLY MADE MINOR ADJUSTMENTS TO
THE FORECAST IN THE LATER PERIODS.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 21 32 17 37 / 50 10 10 10
HOBART OK 18 35 13 36 / 10 0 0 0
WICHITA FALLS TX 24 40 18 40 / 10 10 10 10
GAGE OK 11 30 7 32 / 40 0 0 0
PONCA CITY OK 16 30 10 35 / 70 10 10 10
DURANT OK 28 40 21 43 / 30 10 10 10
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
04/23
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
354 AM CST SUN JAN 13 2013
.SHORT TERM...
A SPRAWLING AND COMPLEX UPPER LEVEL TROUGH WAS DOMINATING THE
WESTERN 2/3RDS OF THE CONUS...WITH SEVERAL EMBEDDED DISTURBANCES
NOTED WITHIN IT. ONE SUCH SHORTWAVE TROUGH WAS GRAZING THE AREA
EARLY THIS MORNING...WITH ANOTHER CURRENTLY DIVING DOWN THE SOUTHERN
CALIFORNIA COAST PROGGED TO APPROACH FROM THE WEST LATE TONIGHT. THE
FORMER HAS PROVIDED STRONG ENOUGH LIFT TO PRODUCE A BAND OF SNOW
THAT HAS TRAVERSED THE NORTHWEST AND NORTH-CENTRAL ZONES EARLY THIS
MORNING. EVEN THOUGH THE PRESENTATION ON RADAR WITHIN THIS BAND HAS
NOT BEEN OVERLY IMPRESSIVE AND MOISTURE IS RATHER LIMITED...THE BAND
HAS BEEN ABLE TO SQUEEZE OUT EFFICIENT SNOW RATES GIVEN THE COLD
TEMPERATURES AND HIGH SNOW TO LIQUID RATIOS. FRIONA REPORTED A QUICK
1-2 INCHES OF SNOW AS THE BAND MOVED THROUGH EARLIER THIS
MORNING...WITH DIMMITT AND TULIA REPORTING LESS THAN 1 INCH. LIFT
SUPPORTING THIS BAND WILL GRADUALLY WANE MOVING TOWARDS
DAYBREAK...BUT A LITTLE LIGHT SNOW OR FLURRIES COULD LINGER PAST 12Z
ACROSS THE NORTHEAST ZONES.
OTHERWISE...COLD SFC RIDGING WILL DOMINATE THE REGION THROUGH THE
SHORT TERM. LOW STRATUS CLOUDS HAVE DEVELOPED ACROSS ROUGHLY THE
NORTHWEST HALF OF THE CWA IN THIS REGIME EARLY THIS MORNING. BOTH
THE NAM AND GFS SUGGEST THESE CLOUDS WILL QUICKLY SCATTER OUT THIS
MORNING AS MID- AND UPPER-LEVEL SUBSIDENCE INCREASES IN THE WAKE OF
THE PASSING SHORTWAVE TROUGH. ON THE OTHER HAND...THE RUC AND HRRR
SUGGEST THAT THE LOW CLOUDS MAY HANG ON MUCH OR ALL OF THE DAY ON
THE CAPROCK AS WINDS VEER EASTERLY AND THE SHALLOW BUT RELATIVELY
MOIST UPSLOPE FLOW ENSUES. CURRENT FORECAST IN THE GRIDS DOES
INDICATE CLEARING SKIES BY MIDDAY...BUT IF THIS DOES NOT
OCCUR...FORECAST HIGHS WILL LIKELY BE TOO HIGH. REGARDLESS...IT WILL
BE A CHILLY DAY AND HAVE FAVORED THE LOW SIDE OF MOS GUIDANCE WITH
FORECAST HIGHS IN THE LOWER TO MIDDLE 30S FOR ALL BUT THE NORTHWEST
ZONES WHERE UPPER 20S WERE CARRIED.
CHILLY EASTERLY UPSLOPE FLOW WILL CONTINUE THROUGH TONIGHT. PROGGED
SOUNDINGS INDICATE MOSTLY CLEAR SKIES EARLY ON...WITH SOME MID-LEVEL
CLOUDS VISITING AT LEAST THE NORTHWEST ZONES LATE AS THE NEXT
SHORTWAVE TROUGH RACES BY. HOWEVER...GIVEN THE UPSLOPE FLOW WOULD
NOT BE SURPRISED IF SOME LOWER CLOUDS DEVELOP OR PERSIST. ALTHOUGH
MODELS ARE GENERALLY DRY...THINK THERE MAY BE ENOUGH LIFT AND
MOISTURE TO SQUEEZE OUT A FEW FLURRIES ACROSS THE WESTERN ZONES LATE
TONIGHT AND HAVE INSERTED THIS INTO THE FORECAST. EXTENT AND
DURATION OF ANY CLOUD COVER COULD HAVE SOME IMPACTS ON EXACTLY HOW
COLD IT GETS TONIGHT...BUT EITHER WAY IT WILL BE CHILLY AND HAVE
MAINTAINED LOWS 10-15 DEGREES BELOW MID-JANUARY AVERAGES /RANGING
FROM 9 DEGREES NORTHWEST TO MID-TEENS OUT EAST/.
&&
.LONG TERM...
THE MON THRU THU FORECAST HINGES ON THE STRENGTH AND TRACK OF THE
SRN PORTION OF THE UPPER-LEVEL TROUGH...INITIALLY LOCATED OVER AZ
AND NM MONDAY MORNING. THE MAJORITY OF GUIDANCE ELONGATES THE TROUGH
FROM THE SW TO NE AS IT SLIDES SEWD ACROSS WEST TEXAS...WITH
MOISTURE AND LIFT BOTH LACKING TO WRING OUT ANY PRECIPITATION FOR
OUR AREA...BEFORE IT EVENTUALLY CLOSES OFF AT 500 MB ACROSS NORTH
CENTRAL TX. HOWEVER...THERE ARE STILL A FEW MODELS /E.G. 0Z NAM
AND CMC/ AND SOME GEFS ENSEMBLE MEMBERS THAT CLOSED OFF TROUGH
INTO A CUTOFF LOW ACROSS SRN NM OR NRN MX...THEN TRACK IT SLOWLY
EAST ACROSS WEST TEXAS MID-WEEK. IN THE LATTER CASE COULD BRING
A CHANCE OF SOME RAIN OR SNOW IN THE TUE THRU THU TIME FRAME AS
BOTH MOISTURE ADVECTION AND LIFT WOULD BE ENHANCED. BUT
PREPONDERANCE OF GUIDANCE SUGGESTS THE OPEN WAVE PASSAGE
ACCOMPANIED BY ONLY AN INCREASE IN MID-LVL CLOUD COVER. THUS WE/VE
KEPT POPS BELOW MENTION THROUGH THE EXTENDED PERIOD...ALTHOUGH
NUDGED THEM UP TO 10 PERCENT ACROSS OUR SRN ZONES. MONDAY STILL
APPEARS TO BE THE COOLEST DAY IN THE PERIOD...WITH HIGHS ONLY IN
THE LOW TO MID 30S. TUESDAY WILL ONLY BE SLIGHTLY WARMER...WITH
HIGHS IN THE UPPER 30S TO LOW 40S. FINALLY...BARRING THE CLOSED
LOW SOLUTION...HIGHS WILL WARM BACK INTO THE UPPER 40S AND 50S WED
AND THU.
FRI-SAT: AFTER THE TROUGH/LOW PASSES...WEAK ZONAL TO SW FLOW SHOULD
EXTEND OVER THE AREA AS A BROAD LOW-AMPLITUDE TROUGH DEVELOPS OVER
THE DESERT SOUTHWEST. SOME SUB-TROPICAL MOISTURE MAY GET DRAWN UP BY
THE TROUGH TO BRING SOME HIGH CLOUD COVER TO THE AREA BY FRIDAY. AND
JUST TO OUT NORTH...UPPER FLOW WILL BECOME CYCLONIC AS A DEEP
TROUGH DROPS INTO THE GREAT LAKES REGION...WHILE THE UPPER RIDGE RE-
AMPLIFIES ALONG THE PACIFIC COAST. TEMPS WILL CONTINUE TO BE MILD
WITH HIGHS MAINLY IN THE MID TO UPPER 50S.
A WEAK FRONT IS EXPECTED TO MOVE INTO THE AREA BY SUNDAY...RESULTING IN
A MODEST COOL DOWN DEPENDING ON THE TIMING OF THE FROPA. A MUCH
STRONGER FRONT IS POSSIBLE BY MONDAY THE 21ST...AS A 1050MB SFC RIDGE
DIVES OUT OF CENTRAL CANADA INTO THE PLAINS. IT IS STILL TOO EARLY
TO TELL IF THIS COLD AIR MASS WILL SETTLE INTO WEST TEXAS OR IF
WE/LL ONLY RECEIVE A GLANCING BLOW.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 28 9 29 9 37 / 10 10 10 10 10
TULIA 29 10 30 12 38 / 10 0 10 10 10
PLAINVIEW 31 11 31 11 38 / 10 10 10 10 10
LEVELLAND 34 11 32 12 38 / 10 10 10 10 10
LUBBOCK 33 12 33 13 39 / 10 10 0 10 10
DENVER CITY 36 13 32 12 38 / 10 10 10 10 10
BROWNFIELD 36 12 32 13 38 / 10 10 0 10 10
CHILDRESS 35 15 34 15 41 / 20 0 0 0 10
SPUR 35 14 34 15 40 / 10 0 0 0 10
ASPERMONT 37 16 36 14 41 / 0 0 10 0 10
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
23/33
AREA FORECAST DISCUSSION...CORRECTED
NWS TAMPA BAY RUSKIN FL
1040 AM EST SUN JAN 13 2013
.UPDATE (REST OF TODAY THROUGH TUESDAY)...
15Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A HIGHLY AMPLIFIED UPPER
LEVEL PATTERN REMAINS IN PLACE OVER THE CONUS. PATTERN CONSISTS OF A
LARGE AND IMPRESSIVE LONGWAVE TROUGH OVER THE WESTERN 2/3RDS OF THE
CONUS FOLLOWED DOWNSTREAM BY LONGWAVE RIDGING EXTENDING FROM THE
EASTERN GULF OF MEXICO NORTHWARD ALONG THE ATLANTIC SEABOARD. THE
DOMINANT WESTERN TROUGH IS BEGINNING TO WIN THE OVERALL BATTLE AND
WE WILL SEE THE NORTHERN PORTION OF THE EASTERN RIDGE QUICKLY BREAK
DOWN OVER THE NEXT 24 HOURS. LUCKILY FOR THOSE WITH OUTDOOR
PLANS...GLOBAL GUIDANCE IS IN GOOD AGREEMENT THAT THE RIDGE WILL
HOLD STRONG THROUGH TUESDAY OVER OUR HEADS AND KEEP OUR WEATHER
CONTINUED DRY AND UNSEASONABLY WARM.
AT THE SURFACE...HIGH PRESSURE CENTERED OFF THE NORTHEAST FLORIDA
COAST CONTINUES TO RIDGE BACK TO THE WEST ACROSS NORTHERN PORTIONS
OF THE STATE. THIS RIDGE AXIS IS EXPECTED TO SETTLE A BIT FURTHER
SOUTH THE NEXT DAY OR 2. THE WEAKER GRADIENT AND CONTINUED STRONG
SURFACE HEATING WILL LEAD TO BETTER CHANCES FOR FEEBLE AFTERNOON
SEA-BREEZES NEAR THE COAST...ESPECIALLY ALONG THE NATURE COAST WHERE
THE LAND/SEA TEMP GRADIENT REMAINS THE GREATEST. MAY BE A BIT COOLER
THE NEXT FEW AFTERNOON ALONG THE IMMEDIATE COAST OF THE NATURE COAST
DO TO THIS ONSHORE FLOW.
12Z KTBW SOUNDING PROFILE CONTINUES TO SHOW THE INFLUENCE OF THE
UPPER RIDGE WITH A SUBSIDENCE INVERSION AROUND 850MB...AND A DRY
COLUMN ABOVE. MOISTURE LEVELS INCREASE NEAR THE TOP OF THE COLUMN IN
THE FORM OF SOME "WISPY" CIRRUS TRYING TO OVERSPREAD FROM THE WEST.
SO FAR...MUCH OF THIS CIRRUS HAS BEEN EVAPORATING AS IT APPROACHES
THE SUPPRESSION OF THE RIDGE AXIS. LIKELY WILL SEE THIS TREND
CONTINUE...AND WE CAN CONSIDER SKIES REMAINING A FILTERED PARTLY TO
MOSTLY SUNNY THROUGH THE AFTERNOON.
OVERALL THE SYNOPTIC PATTERN WILL HOLD THROUGH TUESDAY AND SEE
LITTLE REASON TO MAKE SIGNIFICANT CHANGES TO THE INHERITED FORECAST
AT THIS TIME.
&&
.AVIATION...
VFR TODAY WITH MAINLY INCREASING HIGH CLOUDS. SOME PATCHY FOG
POSSIBLE MONDAY MORNING ESPECIALLY AT FOG PRONE PGD.
&&
.MARINE...
HIGH PRESSURE CENTERED OFF THE SOUTHEAST COAST WILL CONTINUE TO
RIDGE BACK TO THE WEST ACROSS THE FLORIDA PENINSULA AND NORTHEAST
GULF OF MEXICO THROUGH TUESDAY. THIS RIDGE WILL WEAKEN AND SHIFT
EAST BY WEDNESDAY AS A WEAK COLD FRONT APPROACHES FROM THE NORTH.
THIS FRONT IS EXPECTED TO ARRIVE ACROSS THE EASTERN GULF OF MEXICO
DURING THURSDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 81 64 79 61 / 0 10 0 10
FMY 84 62 80 62 / 0 0 0 10
GIF 82 59 81 59 / 0 0 0 10
SRQ 81 62 78 60 / 0 0 0 10
BKV 83 56 81 53 / 0 10 0 10
SPG 80 65 78 64 / 0 0 0 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE/MARINE...MROCZKA
AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
834 AM CST SUN JAN 13 2013
.DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* LOW END MVFR CIGS...POSSIBLY BRIEFLY IFR...THROUGH EARLY THIS
AFTERNOON AND THEN GRADUAL IMPROVEMENT INTO EARLY THIS EVE.
* SMALL POTENTIAL FOR FREEZING DRIZZLE THIS MORNING.
* SMALL CHANCE FOR -SN THIS AFTERNOON.
* WINDS TURNING WNW WITH SOMEWHAT MORE FREQUENT GUSTS BY MID TO
LATE AFTERNOON.
MTF/TRS
//DISCUSSION...UPDATED 14Z...
RAP OUTPUT SEEMS TO HAVE HANDLING ECHO LOCATION OVER THE LAST FEW
HOURS AND HAS AN AREA EXPANDING FROM FAR SE MO NORTHEASTWARD
ACROSS SOUTHERN AND EASTERN IL INTO NORTHERN IN DURING MID
MORNING TO EARLY AFTERNOON. THIS KEEPS MOST IF NOT ALL
SIGNIFICANT PRECIPITATION TO THE E THROUGH SE OF ORD AND MDW...
WITH GYY HAVING BEST CHANCE OF SEEING SOME -SN MID TO LATE
AFTERNOON AS THE SHORT WAVE OVER FAR NE TX AND SW OK CONTINUES TO
LIFT NORTHEASTWARD TO THE MID MS VALLEY BY 14.00Z.
PREVIOUS DISCUSSION...UPDATED 12Z...
LOW PRESSURE OVER LAKE ERIE WILL CONTINUE TO PROGRESS NORTHEAST
TODAY. REMNANT AMPLE LOW-LEVEL MOISTURE AND SOME WEAK FORCING HAS
AIDED IN A RE-EXPANSION OF DRIZZLE THIS MORNING. THIS SHOULD BE
SOMEWHAT TRANSIENT...BUT WHERE IT OCCURS WILL BE ENOUGH TO
POTENTIALLY CREATE IFR CIGS AND VISBYS. A STRONG UPPER JET OVER
THE AREA WILL BRING A DISTURBANCE OVER THE REGION THIS AFTERNOON.
MOST OF THE LIGHT SNOW WITH THIS DURING THE AFTERNOON WILL REMAIN
TO THE SOUTHEAST OF THE AIRPORTS...WITH GYY AND MDW POTENTIALLY
BEING THE EXCEPTIONS. SMALL ACCUMULATION WILL BE POSSIBLE AT GYY.
LOW CIGS WILL BE STEADY THIS MORNING BEFORE LIKELY SHOWING SOME
IMPROVEMENT THIS AFTERNOON AS DRIER AIR PUSHES EASTWARD IN THE
BOUNDARY LAYER. WINDS WILL SLOWLY BACK TO WNW THIS AFTERNOON AND
INCREASE IN GUSTINESS AS COLD AIR ADVECTION INCREASES IN THE WAKE
OF THE WAVE.
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN CIG TRENDS.
* LOW CONFIDENCE IN ANY FREEZING DRIZZLE THIS MORNING.
* MODERATE CONFIDENCE IN AREA OF -SN DURING MID TO LATE AFTERNOON
STAYING TO E THROUGH SE OF IMMEDIATE CHI AREA.
* MEDIUM CONFIDENCE IN WIND TRENDS.
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ741-LMZ742 UNTIL 10 AM SUNDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
557 AM CST SUN JAN 13 2013
.DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* LOW END MVFR CIGS...POSSIBLY BRIEFLY IFR...THROUGH EARLY THIS
AFTERNOON AND THEN GRADUAL IMPROVEMENT INTO EARLY THIS EVE.
* PATHCHY FREEZING DRIZZLE THIS MORNING.
* A SMALL CHANCE FOR AFTERNOON -SN.
* WINDS TURNING WNW WITH SOMEWHAT MORE FREQUENT GUSTS BY MID TO
LATE AFTERNOON.
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE OVER LAKE ERIE WILL CONTINUE TO PROGRESS NORTHEAST
TODAY. REMNANT AMPLE LOW-LEVEL MOISTURE AND SOME WEAK FORCING HAS
AIDED IN A RE-EXPANSION OF DRIZZLE THIS MORNING. THIS SHOULD BE
SOMEWHAT TRANSIENT...BUT WHERE IT OCCURS WILL BE ENOUGH TO
POTENTIALLY CREATE IFR CIGS AND VISBYS. A STRONG UPPER JET OVER
THE AREA WILL BRING A DISTURBANCE OVER THE REGION THIS AFTERNOON.
MOST OF THE LIGHT SNOW WITH THIS DURING THE AFTERNOON WILL REMAIN
TO THE SOUTHEAST OF THE AIRPORTS...WITH GYY AND MDW POTENTIALLY
BEING THE EXCEPTIONS. SMALL ACCUMULATION WILL BE POSSIBLE AT GYY.
LOW CIGS WILL BE STEADY THIS MORNING BEFORE LIKELY SHOWING SOME
IMPROVEMENT THIS AFTERNOON AS DRIER AIR PUSHES EASTWARD IN THE
BOUNDARY LAYER. WINDS WILL SLOWLY BACK TO WNW THIS AFTERNOON AND
INCREASE IN GUSTINESS AS COLD AIR ADVECTION INCREASES IN THE WAKE
OF THE WAVE.
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM CONFIDENCE IN CIG TRENDS. LOW CONFIDENCE IN DURATION OF
LOW CLOUDS.
* LOW CONFIDENCE IN FREEZING DRIZZLE THIS MORNING AND -SN THIS
AFTERNOON. IF FREEZING DRIZZLE OCCURS...MEDIUM CONFIDENCE
VISIBILITY WILL DROP TO BELOW SM.
* MEDIUM CONFIDENCE IN WIND TRENDS.
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ741-LMZ742 UNTIL 10 AM SUNDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
942 AM EST SUN JAN 13 2013
.Forecast Update...
Issued at 940 AM EST Sun Jan 13 2013
The first heavier wave of precipitation has pushed to the east this
morning with mostly light rain across much of the forecast area.
Southwest portions of central Kentucky are most likely seeing some
moderate rain at this time. The highest rainfall report we have
received for the last 24 hours is a bit over 2 inches, though
portions of Dubois county have likely seen higher amounts.
Though the rain has begun to move out of southern Indiana, it looks
to increase again this afternoon. Another wave of rain is moving
across Arkansas. The latest runs of the rapid refresh and HRRR show
this area moving across the northwestern portions of the forecast
area. Additionally, some heavier rain showers look to continue to
move out of central TN into could central Kentucky. All told, much
of the region may see an additional one to possibly two inches of
rain today. Though not much areal flooding has been reported yet, it
will still be possible this afternoon as rains move once again
across saturated grounds.
Have adjusted the forecast based on current trends. In addition,
temperatures behind the front are falling faster than the previous
forecast, so did some adjustments to the hourly temps as well.
Updates are already out.
&&
.Short Term (Today through Monday)...
Issued at 330 AM EST Sun Jan 13 2013
...Flood Watch in Effect through Sunday Evening for areas along and
west of I-65...
Several disturbances ejecting out of strong southwest flow along a
slow-moving baroclinic zone will be the main story this short term
period. Heavy rain, strong winds, and even some wintry
precipitation on the backside all look in play over the next 36
hours.
The synoptic boundary is currently draped from western Ohio
southwest through southern Indiana and western Kentucky. As waves
ride along this boundary, convergence is enhanced and there have
been several rounds of strong, to occasionally severe thunderstorms
as storms accelerate along the mesoscale cold front. Radar has
shown a weakening trend over the last hour or so, and expect that to
be the general rule through early this morning. However, with 40-50
knots just off the surface, the stronger showers and isolated
thunderstorms will be able to pull down higher momentum air,
resulting in gusts up to 50 MPH.
The strong thunderstorm threat should continue to wane through the
morning hours as storms outrun the better instability. Then the
attention turns to the heavy rain potential. The 13/00Z NAM has a
pretty good handle on current trends, albeit a bit slow with the
precipitation. Thus, have leaned on it for the short term forecast,
but bringing things in a bit quicker. PWATs have risen to near 1.5
inches overnight (00Z OHX sounding came in with 1.29) and warm cloud
depths will remain at 10-12 thousand feet today. Copious moisture
transport on the nose of a low-level jet will feed into the
slow-moving boundary, producing moderate to locally heavy rainfall.
In addition, latest guidance continues to advertise another synoptic
shortwave lifting northeast along the boundary late this morning
into early this afternoon. This will help enhance precipitation
rates, especially across south central Kentucky generally west of
I-65. Think that 2 to 3 inches is possible there, with locally
higher amounts. Elsewhere, generally 1-2 inches is likely as the
front slowly progresses east.
In addition to the heavy rain potential, another added element to
this system is the chance for wintry precipitation as the front
exits. However, latest guidance continues to speed up the
progression of the precipitation, seemingly outrunning the colder
air. However, model soundings do still hint at some "freezing" rain
potential on the backside. I say "freezing", due to the fact that
the ground will be rather wet and warm still, so although surface
temperatures will slide below freezing, no ice accumulation is
expected beside maybe a real light glaze on elevated surfaces.
Otherwise, the system slides to the far southeastern CWA on Sunday
night, ending all precipitation. With many surfaces still remaining
wet, there is a chance of some isolated black ice as temperatures
quickly fall Sunday night into Monday morning. Will have to monitor
this potential closely in the coming 24 hours.
Temperatures will continue to remain very mild this morning ahead of
the cold front, before crashing later in the day as the front sweeps
through. Lows will drop into the low 20s in southern Indiana and
the low 30s across southern KY. Highs on Monday will only climb
into the 30s and lower 40s.
.Long Term (Monday Night - Saturday)...
Issued at 320 AM EST Sun Jan 13 2013
Did not spend time diagnosing the models this forecast cycle because
of returns on 88D. Have blended with the previous forecast with the
new set of model consensus. The product is a forecast that has lows
near normal each day and highs not straying too far from normal
either. Rain chances are limited to the south and east forecast area
Monday night through Tuesday night. Model soundings indicate
temperatures close to freezing for most of the lower levels of the
atmosphere, so cannot rule out either rain or snow, should model
surface and low-level temperatures be off, so will continue to
advertise generally a rain/snow mix. Otherwise, from Wednesday on,
this forecast package will be dry.
&&
.Aviation (12Z TAF Issuance)...
Issued at 634 AM EST Sun Jan 13 2013
Moderate to heavy rainfall continues to push east across all sites
this morning as a slow-moving cold front pushes across the region.
This will bring a prolonged period of MVFR to IFR conditions to all
sites through much of the TAF cycle.
Ceilings have been slow to lower this morning despite the rather
intense rainfall. However, upstream observations show that MVFR, or
even isolated IFR ceilings are on the doorstep of all sites.
Expect sites to bounce around both in visibilities and ceilings
throughout the day in the precipitation, from MVFR to high end IFR.
An extended area of IFR is apparent along the trailing edge of the
precipitation. Have used the latest guidance and observational
trends to time this area of prevailing IFR through KSDF and KBWG.
Thunderstorms will remain isolated as this system shifts east, so
have only put thunder in the KBWG TAF, where thunder is OCCURING now
and will continue for the next hour. However, an isolated rumble is
possible across all sites through the next several hours.
Winds have been rather random this morning as well, as individual
showers and waves along the boundary have shifted them in all
directions. Tried to time the synoptic boundary through the TAF
sites as best as possible, but winds will undoubtedly shift around
as outflow from showers affect sites.
Conditions should generally improve toward the end of the TAF
period, going back to VFR by early Monday morning as this system
pushes east.
&&
.Hydrology...
Unseasonably warm, moist air continues to be pooled into the Ohio
Valley. Decent amounts of rain continue to fall ahead of and along
an approaching cold front as the atmosphere is laden with moisture.
Precipitable water values are unseasonably high for this time of
year. Numerous rain showers are expected to continue throughout the
day. Additional rain amounts today look to be in the 1 to 2 inch
range. QPF totals are anticipated to be from about 1.5 to 4 inches
with locally higher amounts will be possible.
What this all translates to is the possibility for some minor areal
(see the issued Flood Watch for more details) and river flooding to
occur along prone banks. The location to watch initially looks to be
Dundee on the Rough River in the Green River basin which may reach
flood stage tonight. Additional spots to watch over the next 24 to
36 hours include locations along the Green and Salt River basins as
well as small creeks and streams. This includes Rochester, Alvaton
(Drakes Creek), Woodbury, and Boston (Rolling Fork River). As the
precipitation moves off toward the north and east, additional basins
will be under close observation as the rain flows downstream.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...FLOOD WATCH UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
INZ076>079-083-084-089>092.
KY...FLOOD WATCH UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
KYZ023>030-053-061>063-070>075.
$$
Update...........EER
Short Term.......KD
Long Term........RJS
Aviation.........KD
Hydrology........LG/AMS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
914 AM EST SUN JAN 13 2013
.SYNOPSIS...
ISSUED AT 325 AM EST SUN JAN 13 2013
A MIX OF PRECIPITATION INCLUDING SOME FREEZING RAIN THIS MORNING
WILL TRANSITION TO LIGHT SNOW SHOWERS THIS AFTERNOON. LIGHT SNOW
SHOWERS WILL CONTINUE TONIGHT INTO MONDAY. FAIRLY CLOSE TO NORMAL
TEMPERATURES ARE EXPECTED MOST OF THE UPCOMING WEEK WITH OCCASIONAL
LIGHT SNOW SHOWERS AND FLURRIES FROM TIME TO TIME.
&&
.UPDATE...
ISSUED AT 915 AM EST SUN JAN 13 2013
I UPDATED SINCE THERE IS MORE DRIZZLE THEN WAS CURRENTLY IN THE
FORECAST AND ALSO SINCE ALL OF THE MODELS I JUST LOOKED AT
(HRRR...RAP...NAM12...GFS AND ECMWF) ALL SHOW THE NEXT WAVE BRINGING
MEASURABLE PRECIPITATION TO NEARLY ALL OF THE CWA LATE THIS
AFTERNOON INTO THIS EVENING. SATELLITE LOOPS SHOW THE WAVE IS REAL
AND RADAR LOOPS ALSO SHOW THE WAVE NEEDING NORTHEAST FORM AR AND
MO HEADING THIS WAY TOO.
CURRENTLY THERE IS A DRY LAYER BETWEEN 10000 FT AND 20000 FT AS
SEEN ON RAP MODEL SOUNDINGS THAT IS NOT ALLOWING THE DGZ TO BE
SATURATED SO DRIZZLE/LIGHT RAIN IS FALLING INSTEAD OF SNOW OVER
OUR WESTERN CWA. BY EARLY TO MID AFTERNOON THE DEEPER MOISTURE
FROM THE NEXT SHORTWAVE COMES BACK IN SO THEN THE PRECIPITATION
SHOULD LARGELY BE SNOW FROM GRR NORTH AND WEST AND TRANSITION FROM
MIXED PRECIPITATION TO SNOW SOUTH AND EAST OF GRR (BY EVENING). I
DO NOT EXPECT MUCH SNOW OUT OF THIS... MOSTLY AN INCH OR LESS.
THIS MAY NEED UPDATING THROUGH.
UPDATE ISSUED AT 702 AM EST SUN JAN 13 2013
WILL BE CAN CELLING THE WINTER WEATHER ADVISORY AS BOTH RADAR AND
HRRR MODEL GUIDANCE INDICATE WE SHOULD BE PRECIPITATION FREE FOR
THE NEXT SEVERAL HOURS. ROAD WEATHER SENSORS AT CADILLAC/REED
CITY/LUDINGTON SHOW SURFACE TEMPERATURES STILL AROUND 33-35F EVEN
THOUGH AIR TEMPERATURES HAVE GENERALLY FALLEN BELOW FREEZING. ALL
OF THIS SUGGESTS THAT THERE SHOULD BE LITTLE EFFECT ON TRAVEL
CONDITIONS THE REST OF THIS MORNING. UPDATED FORECASTS WILL BE
COMING OUT SHORTLY.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY AFTERNOON)
ISSUED AT 325 AM EST SUN JAN 13 2013
OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO EVALUATE POTENTIAL FOR
FZRA THIS MORNING.
KGRR/RGNL RADAR TRENDS SHOW A LARGE AREA OF LGT TO MDT PCPN OVER OUR
AREA WITH RAIN NEAR TO SOUTH OF I-96 AND SOME MIXED PCPN BEING
REPORTED OVER OUR NORTHERN COUNTIES. SFC OBS AND LOCAL STORM REPORTS
INDICATE FAIRLY EXTENSIVE LIGHT TO MODERATE FZRA UPSTREAM ACROSS
PORTIONS OF WI/IL. PCPN WILL TRANSITION TO A PERIOD OF FZRA THIS
MORNING AS SFC TEMPS CONTINUE TO FALL SLOWLY TO FREEZING.
OUR GOING WINTER WX ADVISORY HEADLINE WILL REMAIN UNCHANGED WITH
HAZARDOUS TRAVEL CONDITIONS LIKELY TO DEVELOP A LITTLE LATER THIS
MORNING (TOWARD DAYBREAK THROUGH LATE MORNING) GIVEN THE MIXED
PCPN/FZRA AND SLOWLY FALLING SFC TEMPS IN NORTHERLY FLOW CAA.
PCPN WILL TRANSITION TO LIGHT SNOW SHOWERS THIS AFTN. LIGHT SNOW
SHOWERS WILL CONTINUE TONIGHT AND MONDAY BUT WITH VERY LIGHT
ACCUMULATIONS OF GENERALLY ONLY AROUND AN INCH OR LESS. MOST OF THAT
WILL COME THIS AFTERNOON AND TONIGHT WITH ONLY VERY LIGHT SNOW
SHOWERS AND FLURRIES EXPECTED TO LINGER MONDAY.
A FEW FLURRIES MAY LINGER INTO MONDAY NIGHT BUT MAINLY DRY
CONDITIONS ARE EXPECTED FOR THIS TIME FRAME WITH A SFC RIDGE IN
PLACE OVER THE LOWER GREAT LAKES REGION.
.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 325 AM EST SUN JAN 13 2013
MAIN CHANGE WAS TO INCREASE CHANCES FOR SNOW WEDNESDAY NIGHT AND
THURSDAY. LAST COUPLE RUNS OF THE PREFERRED ECMWF MODEL ADVERTISE A
MODERATELY STRONG CLIPPER AND ASSOCIATED COLD FRONT PASSING THROUGH
WEDNESDAY NIGHT. LAKE ENHANCED SNOW BEHIND THE CLIPPER LOOKS A BIT
MORE FAVORABLE EARLY THURSDAY WITH BETTER SATURATION IN THE DGZ AND
A BRIEF PERIOD OF COLD ADVECTION /850 MB TEMPERATURES DROPPING TO
AROUND -20C/.
OTHERWISE...NO OTHER SIGNIFICANT CHANGES WERE MADE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 634 AM EST SUN JAN 13 2013
MAIN CHANGES TO TAFS WERE TO DELAY THE TRANSITION FROM RAIN...TO FREEZING
RAIN/ICE PELLETS...TO SNOW ACROSS THE TERMINALS FROM NORTHWEST TO SOUTHEAST.
RADAR AND COMPUTER MODELS INDICATE A LULL IN PRECIPITATION THAT SHOULD
LAST MOST OF THE MORNING ACROSS SOUTHWEST LOWER MICHIGAN.
EXPECT IFR CIGS EARLY THIS MORNING AT MOST TERMINALS GRADUALLY LIFTING
BUT LIKELY STAYING BELOW FUEL ALTERNATE THRESHOLD OF 2000 FT AGL AREAWIDE.
CIGS ARE THE GREATEST CONCERN FOR FLIGHT RESTRICTIONS AND UNFORTUNATELY
A LOT OF UNCERTAINTY EXISTS IN THIS CRITICAL ASPECT OF THE FORECAST.
OTHERWISE...MODERATE INTENSITY PRECIPITATION MIGHT BRIEFLY DROP
VISIBILITIES BELOW FUEL ALTERNATE THRESHOLDS THIS AFTERNOON AT THE
KAZO/KBTL/KJXN TERMINALS.
&&
.MARINE...
ISSUED AT 325 AM EST SUN JAN 13 2013
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH MONDAY AS WAVE
HEIGHTS STAY UP TODAY WITH NORTHWEST TO NORTH WINDS AND COLDER AIR
MOVING IN. BRISK WEST WINDS WILL KEEP WAVE HEIGHTS UP TONIGHT INTO
MONDAY.
&&
.HYDROLOGY...
ISSUED AT 325 AM EST SUN JAN 13 2013
MODEST RIVER LEVEL RISES ARE ANTICIPATED IN RESPONSE TO THE RAINFALL
OVERNIGHT BUT NO SIGNIFICANT HYDRO ISSUES ARE EXPECTED SINCE
SIGNIFICANT PRECIPITATION WILL MOVE OUT LATER TODAY AND WITH THE
SIGNIFICANT COOLING TREND OF TEMPS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 3 PM EST MONDAY FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...93
AVIATION...TJT
HYDROLOGY...LAURENS
MARINE...LAURENS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
707 AM EST SUN JAN 13 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 533 AM EST SUN JAN 13 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
CENTRAL CANADA THROUGH THE WRN PLAINS AND A RIDGE OFF THE EAST COAST
RESULTING IN SW FLOW FROM THE SRN PLAINS INTO THE GREAT LAKES. AN
UPSTREAM SHORTWAVE TROUGH WAS LOCATED OVER NEBRASKA. AT THE
SFC...THE MAIN TROUGH/FRONT AND FOCUS FOR HEAVIER PCPN WAS LOCATED WELL
TO THE SOUTH...FROM NW OH THROUGH WRN KY INTO NRN MS. TO THE
WEST...AN ARCTIC HIGH PRES RIDGE EXTENDED FROM ALBERTA/SASK INTO THE
WRN PLAINS. WITH MAINLY NW LOW LEVEL FLOW ACROSS THE NRN LAKES...LAKE
INDUCED TROUGHING HAS KEPT LOW LEVEL CONV FOCUSED NEAR THE LAKE FROM
IWD-P59. EVEN THOUGH 850 MB TEMPS TO AROUND -20C OVER WRN LAKE
SUPERIOR PROVIDED PLENTY OF INSTABILITY(LAKE INDUCED CAPE VALUES TO
AROUND 400 J/KG) LOW INVERSION HEIGHTS AROUND 4K FT WITH PROMINENT
MID LEVEL DRYING HAS LIMITED LES RATES WITH ONLY LIGHT ACCUMULATIONS
OF A FEW INCHES OVERNIGHT. THE DRY AIR...SLIGHTLY LOWER INVERSION
HEIGHTS AND 850 MB TEMPS ONLY NEAR -12C...HAS INHIBITED LES OVER THE
ERN LAKE.
MAIN FCST CONCERNS ARE LES TRENDS.
MODELS WERE CONSISTENT IN BRINGING THE NEBRASKA SHRTWV NORTHEAST
THROUGH THE WRN GREAT LAKES. EVEN WITH MODERATE TO STRONG 700-300 MB
QVECTOR CONV AHEAD OF THE SHRTWV...LITTLE SYNOPTIC PCPN IS EXPECTED
IN THE DRY AIRMASS TO THE NORTH OF THE MAIN FRONTAL BOUNDARY. SOME
LIGHT SNOW WILL BE POSSIBLE WITH THIS FEATURE WITH ANY ACCUMULATIONS
AMOUNTING TO TO A HALF INCH OR LESS.
THE MAIN IMPACT WILL BE TO INVIGORATE THE LES...ESPECIALLY LATE THIS
AFTERNOON AND EVENING...AS DEEPER MOISTURE MOVES IN AND INVERSION
HEIGHTS CLIMB AOA 7K FT WITH 850 MB TEMPS AROUND -19C. WITH THE DGZ IN
THE CONVECTIVE LAYER...SNOW/WATER RATIO VALUES SHOULD ALSO REMAIN
HIGH(FROM 25/1 TO 30/1). VEERING WINDS WILL SHIFT THE FOCUS OF THE
HEAVIER LES TO AREAS BTWN HOUGHTON AND THE PORCUPIN MOUNTAINS AND
ALSO WILL ALLOW THE LES TO PUSH INTO THE EAST (LOCATIONS FROM AU
TRAIN EASTWARD).
ONGOING ADVISORIES AND SNOWFALL AMOUNTS LOOK ON TRACK WITH 12 HOUR
AMOUNTS OF 1 TO 4 INCHES WEST TODAY AND 2 TO 5 INCHES TONIGHT. OVER
THE EAST...1 TO 3 INCHES ARE EXPECTED THIS AFTERNOON WITH AMOUNTS OF
3 TO 6 INCHES POSSIBLE...GREATEST NEAR THE LAKE EAST OF MUNISING.
SOME HIGHER AMOUNTS MAY BE POSSIBLE EAST IF A MORE DOMINANT BAND
DEVELOPS BUT CONFIDENCE IN THE LOCATION IS LIMITED GIVEN SIGNFICNAT
DIFFERENCES BETWEEN THE HIGHER RES MODELS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 426 AM EST SUN JAN 13 2013
WEST TO NORTHWEST FLOW LAKE EFFECT WILL BE ONGOING AT THE START OF
THE LONG TERM PERIOD. BUT WITH THE SURFACE TROUGH OVER EASTERN LAKE
SUPERIOR DIMINISHING DURING THE MORNING DUE TO A HIGH PRESSURE
RIDGE MOVING THROUGH MN...EXPECT THE WINDS TO BACK THROUGH THE DAY
AND BE OUT OF THE WEST-SOUTHWEST BY 00Z TUESDAY. THIS WILL PUSH THE
LAKE EFFECT OFFSHORE OVER THE EAST BY EARLY AFTERNOON AND FOCUS THE
LAKE EFFECT OVER THE KEWEENAW PENINSULA OVER THE WEST. SINCE
INVERSION HEIGHTS ARE STILL IN THE 7-8KFT RANGE AND DELTA-T VALUES
ARE AROUND 22...CONDITIONS ARE FAVORABLE FOR MODERATE SNOW TO
CONTINUE ON MONDAY. WITH THE SOUTHERN EDGE OF THE LAKE EFFECT BAND
BEING AIDED BY ENHANCED CONVERGENCE FROM THE BACKING WINDS...THINK
THERE SHOULD BE AT LEAST ONE STRONGER BAND GRADUALLY DRIFTING NORTH
THROUGH NORTHERN HOUGHTON COUNTY DURING THE DAY. THE BIGGEST
CONCERN WILL BE THE NORTHWARD PUSH IN THE MORNING...WHICH THEN
STALLS IN THE AFTERNOON AS WHAT IS LEFT OF THE SURFACE TROUGH
STALLS OVER THE KEWEENAW. WHERE THIS BAND STALLS OR DOESN/T
STALL WILL DETERMINE SNOWFALL AMOUNTS. BUFKIT SOUNDINGS SHOWING
FAVORABLE CONDITIONS FOR VERY FLUFFY 30-1 SNOW RATIOS...AS THE BEST
OMEGA IS CENTERED RIGHT IN THE DGZ...MUCH OF THE CLOUD IS IN THE
DGZ...AND WIND SPEEDS ARE NOT OVERLY STRONG. WILL FOLLOW THAT IDEA
FOR THE FORECAST AND BUMP RATIOS TOWARDS THAT. WITH THE WAY MODELS
ARE LOOKING...COULD BE A PERIOD OF EVEN HEAVY SNOW DURING THE LATE
MORNING AND AFTERNOON HOURS...SINCE POCKET OF DEEPER H850-700
MOISTURE HELPS PUSH LAKE EFFECT SNOW PARAMETER VALUES WELL OVER 2.
HAVE FINE TUNED THE POPS DURING THIS PERIOD AND BUMPED SNOWFALL
AMOUNTS UP A FEW INCHES. 00Z RUNS OF BOTH THE NESTED 4KM NAM AND OUR
LOCAL WRF-ARW COBB SNOWFALL OUTPUT ARE INDICATING 10IN OF SNOW FOR
KCMX FROM 12Z MONDAY THROUGH 06Z TUESDAY. HAD SOME CONCERN EXTENDING
THE ADVISORY FOR ANOTHER 12HRS SINCE IT WAS A SIGNIFICANT JUMP FROM
PREVIOUS RUNS...BUT WITH GOING FORECAST VALUES OF 3-5 INCHES ON
MONDAY COULDN/T HOLD OFF ON IT.
WITH THE HIGH PRESSURE RIDGE SLIDING EAST ACROSS WISCONSIN ON
MONDAY NIGHT...INDICATIONS ARE THE WINDS BACKING MORE TO THE
SOUTHWEST. THIS WILL PUSH THE STRONGER SNOW TO THE NORTH THROUGH
KEWEENAW COUNTY AND BRING AN END TO THE LES FOR THE CWA FOR
A DAY OR TWO DUE TO H850 TEMPS WARMING TO -10C UNDER THE STRONG
SOUTHWESTERLY FLOW ON TUESDAY.
THIS INCREASING SOUTHWESTERLY FLOW IS IN RESPONSE TO AN APPROACHING
SHORTWAVE AND CLIPPER SYSTEM DROPPING THROUGH THE NORTHWEST FLOW
ALOFT. THIS COULD PRODUCE SOME BREEZY CONDITIONS ON TUESDAY
INTO TUESDAY NIGHT. BOTH NAM/GFS SHOWING H925 WINDS OF
40-50KTS...BUT A WEAK INVERSION MAY BE ENOUGH TO KEEP THAT
FROM REACHING THE SURFACE OVER LAND. OVER LAKE SUPERIOR...BUFKIT
SOUNDINGS SHOWING MUCH OF THAT REACHING THE SURFACE DUE TO STRONG
PRESSURE FALL /14MB IN 12HR/ MOVING ACROSS THE LAKE. THUS...HAVE
BUMPED WINDS UP A SOLID 10KTS TO GALES AND IF LATEST TRENDS ARE
CORRECT THEY WILL NEED TO GO ANOTHER 5-10KTS HIGHER. DEFINITELY
SEEING BETTER AGREEMENT IN THE MODELS WITH THE TIMING/TRACK OF THE
SYSTEM...ALTHOUGH THE ECMWF/GEM ARE A LITTLE FARTHER SOUTH AND
SLOWER WITH AN ELONGATED SURFACE TROUGH AS IT MOVES THROUGH LATE
TUESDAY NIGHT INTO WEDNESDAY. EITHER SOLUTION SHOULD LEAD TO AT
LEAST A DUSTING TO AN INCH OF SNOW CWA WIDE...BUT ECMWF/GEM COULD
PRODUCE SOME AREAS WITH A COUPLE INCHES OF SNOW.
COLD AIR WILL SURGE IN BEHIND THIS CLIPPER...AS THE POLAR VORTEX
DIVES SOUTHEAST TOWARDS JAMES BAY. AT THIS POINT IT LOOKS TO STAY
THERE...BUT IT WILL STILL LEAD TO H850 TEMPS IN THE LOW TO MID -20S.
WITH HIGH PRESSURE CENTERED IN THE CENTRAL PLAINS AND A LOW OVER
HUDSON BAY...EXPECT NORTHWESTERLY WINDS AT THE SURFACE AND THROUGH
H850. THIS WILL LEAD TO PERSISTENT LES IN THAT FAVORED WIND
DIRECTION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. WILL CONTINUE TO
HIGHLIGHT HIGH END LIKELY POPS IN THAT AREA. INTENSITY WILL DEPEND
ON THE INVERSION HEIGHTS AND IF ANY DEEPER MOISTURE OR SHORTWAVES
SWEEP THROUGH. 00Z GFS SHOWING LAKE INDUCED EQL HEIGHTS OF
7-9KFT...BUT MOISTURE REMAINS BELOW 5KFT WITH FORCING ON HIGHER
EDGE OF DGZ. THUS...POTENTIAL IS THERE FOR MODERATE SNOW...BUT
MOISTURE WILL BE CONTROLLING FACTOR.
GFS/ECMWF CONTINUING TO SHOW THE POTENTIAL FOR A WEAK SHORTWAVE
SLIDING THROUGH THE NORTHWEST FLOW ON FRIDAY AND AGAIN ON SATURDAY.
THIS LEADS TO SOME UNCERTAINTY IN THE LAKE EFFECT LOCATIONS AND
JUST LOW END CHANCE OR SLIGHT POPS ACROSS THE REST OF THE CWA.
AFTER A BELOW NORMAL START TO THE WORK WEEK...TEMPERATURES LOOK TO
RETURN TO NORMAL FOR TUESDAY/WEDNESDAY BEFORE FALLING 5-10 DEGREES
BELOW NORMAL FOR THE END OF THE WORK WEEK. FINALLY...00Z GFS HAS
TRENDED TOWARDS WHAT THE ECMWF HAS BEEN SHOWING WITH THE POLAR
VORTEX DIVING SOUTH INTO THE GREAT LAKES ON SUNDAY/MONDAY.
SIGNIFICANT DIFFERENCES IN THE AMOUNT OF COLD AIR BETWEEN THE
MODELS...SO IT WILL BE INTERESTING TO SEE WHICH ONE PANS OUT. IF
ECMWF IS RIGHT...H850 TEMPS WILL BE AROUND -35C AND WOULD LEAD TO
INLAND AREAS ON SLIGHTLY ABOVE ZERO FOR HIGHS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 704 AM EST SUN JAN 13 2013
EXPECT MVFR CONDITIONS TO PREVAIL AT CMX/IWD WITH SURGE OF COLD AIR
OVER THE RELATIVELY WARM WATERS OF LAKE SUPERIOR AND AN UPSLOPE W-NW
WIND. THERE COULD BE SOME HEAVIER SHSN/IFR CONDITIONS MAINLY AT CMX.
SINCE THE NW LOW LEVEL WILL DOWNSLOPE AT SAW...THE MVFR CONDITIONS
MAY GIVE WAY TO VFR AT TIMES. THE APPROACH OF ANOTHER SHORTWAVE
TROUGH THIS AFTERNOON WILL INCREASE CHANCE OF HEAVIER SHSN/IFR
VSBYS AT IWD/CMX IN THE PRESENCE OF AN UPSLOPE WIND. ALTHOUGH SOME
-SHSN MAY IMPACT SAW AS WELL...DOWNSLOPE WIND WILL LIMIT THE POTENTIAL
FOR ANY WORSE THAN MVFR CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 533 AM EST SUN JAN 13 2013
NORTHWEST WINDS ARE EXPECTED TO REMAIN AT OR BELOW 25 KNOTS THROUGH
MONDAY AS HIGH PRESSURE GRADUALLY BUILDS FROM THE PLAINS TOWARD THE
GREAT LAKES. A CLIPPER LOW PRES SYSTEM MOVING INTO SRN MANITOBA
TUESDAY AND NORTHERN ONTARIO TUE NIGHT WILL LIKELY BRING SW GALES
ACROSS LAKE SUPERIOR. AS THE LOW DEEPENS AND MOVES TOWARD NRN QUEBEC
WED...SOME NW GALES MAY ALSO BE POSSIBLE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM EST
MONDAY FOR MIZ006-007.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
536 AM EST SUN JAN 13 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 533 AM EST SUN JAN 13 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
CENTRAL CANADA THROUGH THE WRN PLAINS AND A RIDGE OFF THE EAST COAST
RESULTING IN SW FLOW FROM THE SRN PLAINS INTO THE GREAT LAKES. AN
UPSTREAM SHORTWAVE TROUGH WAS LOCATED OVER NEBRASKA. AT THE
SFC...THE MAIN TROUGH/FRONT AND FOCUS FOR HEAVIER PCPN WAS LOCATED WELL
TO THE SOUTH...FROM NW OH THROUGH WRN KY INTO NRN MS. TO THE
WEST...AN ARCTIC HIGH PRES RIDGE EXTENDED FROM ALBERTA/SASK INTO THE
WRN PLAINS. WITH MAINLY NW LOW LEVEL FLOW ACROSS THE NRN LAKES...LAKE
INDUCED TROUGHING HAS KEPT LOW LEVEL CONV FOCUSED NEAR THE LAKE FROM
IWD-P59. EVEN THOUGH 850 MB TEMPS TO AROUND -20C OVER WRN LAKE
SUPERIOR PROVIDED PLENTY OF INSTABILITY(LAKE INDUCED CAPE VALUES TO
AROUND 400 J/KG) LOW INVERSION HEIGHTS AROUND 4K FT WITH PROMINENT
MID LEVEL DRYING HAS LIMITED LES RATES WITH ONLY LIGHT ACCUMULATIONS
OF A FEW INCHES OVERNIGHT. THE DRY AIR...SLIGHTLY LOWER INVERSION
HEIGHTS AND 850 MB TEMPS ONLY NEAR -12C...HAS INHIBITED LES OVER THE
ERN LAKE.
MAIN FCST CONCERNS ARE LES TRENDS.
MODELS WERE CONSISTENT IN BRINGING THE NEBRASKA SHRTWV NORTHEAST
THROUGH THE WRN GREAT LAKES. EVEN WITH MODERATE TO STRONG 700-300 MB
QVECTOR CONV AHEAD OF THE SHRTWV...LITTLE SYNOPTIC PCPN IS EXPECTED
IN THE DRY AIRMASS TO THE NORTH OF THE MAIN FRONTAL BOUNDARY. SOME
LIGHT SNOW WILL BE POSSIBLE WITH THIS FEATURE WITH ANY ACCUMULATIONS
AMOUNTING TO TO A HALF INCH OR LESS.
THE MAIN IMPACT WILL BE TO INVIGORATE THE LES...ESPECIALLY LATE THIS
AFTERNOON AND EVENING...AS DEEPER MOISTURE MOVES IN AND INVERSION
HEIGHTS CLIMB AOA 7K FT WITH 850 MB TEMPS AROUND -19C. WITH THE DGZ IN
THE CONVECTIVE LAYER...SNOW/WATER RATIO VALUES SHOULD ALSO REMAIN
HIGH(FROM 25/1 TO 30/1). VEERING WINDS WILL SHIFT THE FOCUS OF THE
HEAVIER LES TO AREAS BTWN HOUGHTON AND THE PORCUPIN MOUNTAINS AND
ALSO WILL ALLOW THE LES TO PUSH INTO THE EAST (LOCATIONS FROM AU
TRAIN EASTWARD).
ONGOING ADVISORIES AND SNOWFALL AMOUNTS LOOK ON TRACK WITH 12 HOUR
AMOUNTS OF 1 TO 4 INCHES WEST TODAY AND 2 TO 5 INCHES TONIGHT. OVER
THE EAST...1 TO 3 INCHES ARE EXPECTED THIS AFTERNOON WITH AMOUNTS OF
3 TO 6 INCHES POSSIBLE...GREATEST NEAR THE LAKE EAST OF MUNISING.
SOME HIGHER AMOUNTS MAY BE POSSIBLE EAST IF A MORE DOMINANT BAND
DEVELOPS BUT CONFIDENCE IN THE LOCATION IS LIMITED GIVEN SIGNFICNAT
DIFFERENCES BETWEEN THE HIGHER RES MODELS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 426 AM EST SUN JAN 13 2013
WEST TO NORTHWEST FLOW LAKE EFFECT WILL BE ONGOING AT THE START OF
THE LONG TERM PERIOD. BUT WITH THE SURFACE TROUGH OVER EASTERN LAKE
SUPERIOR DIMINISHING DURING THE MORNING DUE TO A HIGH PRESSURE
RIDGE MOVING THROUGH MN...EXPECT THE WINDS TO BACK THROUGH THE DAY
AND BE OUT OF THE WEST-SOUTHWEST BY 00Z TUESDAY. THIS WILL PUSH THE
LAKE EFFECT OFFSHORE OVER THE EAST BY EARLY AFTERNOON AND FOCUS THE
LAKE EFFECT OVER THE KEWEENAW PENINSULA OVER THE WEST. SINCE
INVERSION HEIGHTS ARE STILL IN THE 7-8KFT RANGE AND DELTA-T VALUES
ARE AROUND 22...CONDITIONS ARE FAVORABLE FOR MODERATE SNOW TO
CONTINUE ON MONDAY. WITH THE SOUTHERN EDGE OF THE LAKE EFFECT BAND
BEING AIDED BY ENHANCED CONVERGENCE FROM THE BACKING WINDS...THINK
THERE SHOULD BE AT LEAST ONE STRONGER BAND GRADUALLY DRIFTING NORTH
THROUGH NORTHERN HOUGHTON COUNTY DURING THE DAY. THE BIGGEST
CONCERN WILL BE THE NORTHWARD PUSH IN THE MORNING...WHICH THEN
STALLS IN THE AFTERNOON AS WHAT IS LEFT OF THE SURFACE TROUGH
STALLS OVER THE KEWEENAW. WHERE THIS BAND STALLS OR DOESN/T
STALL WILL DETERMINE SNOWFALL AMOUNTS. BUFKIT SOUNDINGS SHOWING
FAVORABLE CONDITIONS FOR VERY FLUFFY 30-1 SNOW RATIOS...AS THE BEST
OMEGA IS CENTERED RIGHT IN THE DGZ...MUCH OF THE CLOUD IS IN THE
DGZ...AND WIND SPEEDS ARE NOT OVERLY STRONG. WILL FOLLOW THAT IDEA
FOR THE FORECAST AND BUMP RATIOS TOWARDS THAT. WITH THE WAY MODELS
ARE LOOKING...COULD BE A PERIOD OF EVEN HEAVY SNOW DURING THE LATE
MORNING AND AFTERNOON HOURS...SINCE POCKET OF DEEPER H850-700
MOISTURE HELPS PUSH LAKE EFFECT SNOW PARAMETER VALUES WELL OVER 2.
HAVE FINE TUNED THE POPS DURING THIS PERIOD AND BUMPED SNOWFALL
AMOUNTS UP A FEW INCHES. 00Z RUNS OF BOTH THE NESTED 4KM NAM AND OUR
LOCAL WRF-ARW COBB SNOWFALL OUTPUT ARE INDICATING 10IN OF SNOW FOR
KCMX FROM 12Z MONDAY THROUGH 06Z TUESDAY. HAD SOME CONCERN EXTENDING
THE ADVISORY FOR ANOTHER 12HRS SINCE IT WAS A SIGNIFICANT JUMP FROM
PREVIOUS RUNS...BUT WITH GOING FORECAST VALUES OF 3-5 INCHES ON
MONDAY COULDN/T HOLD OFF ON IT.
WITH THE HIGH PRESSURE RIDGE SLIDING EAST ACROSS WISCONSIN ON
MONDAY NIGHT...INDICATIONS ARE THE WINDS BACKING MORE TO THE
SOUTHWEST. THIS WILL PUSH THE STRONGER SNOW TO THE NORTH THROUGH
KEWEENAW COUNTY AND BRING AN END TO THE LES FOR THE CWA FOR
A DAY OR TWO DUE TO H850 TEMPS WARMING TO -10C UNDER THE STRONG
SOUTHWESTERLY FLOW ON TUESDAY.
THIS INCREASING SOUTHWESTERLY FLOW IS IN RESPONSE TO AN APPROACHING
SHORTWAVE AND CLIPPER SYSTEM DROPPING THROUGH THE NORTHWEST FLOW
ALOFT. THIS COULD PRODUCE SOME BREEZY CONDITIONS ON TUESDAY
INTO TUESDAY NIGHT. BOTH NAM/GFS SHOWING H925 WINDS OF
40-50KTS...BUT A WEAK INVERSION MAY BE ENOUGH TO KEEP THAT
FROM REACHING THE SURFACE OVER LAND. OVER LAKE SUPERIOR...BUFKIT
SOUNDINGS SHOWING MUCH OF THAT REACHING THE SURFACE DUE TO STRONG
PRESSURE FALL /14MB IN 12HR/ MOVING ACROSS THE LAKE. THUS...HAVE
BUMPED WINDS UP A SOLID 10KTS TO GALES AND IF LATEST TRENDS ARE
CORRECT THEY WILL NEED TO GO ANOTHER 5-10KTS HIGHER. DEFINITELY
SEEING BETTER AGREEMENT IN THE MODELS WITH THE TIMING/TRACK OF THE
SYSTEM...ALTHOUGH THE ECMWF/GEM ARE A LITTLE FARTHER SOUTH AND
SLOWER WITH AN ELONGATED SURFACE TROUGH AS IT MOVES THROUGH LATE
TUESDAY NIGHT INTO WEDNESDAY. EITHER SOLUTION SHOULD LEAD TO AT
LEAST A DUSTING TO AN INCH OF SNOW CWA WIDE...BUT ECMWF/GEM COULD
PRODUCE SOME AREAS WITH A COUPLE INCHES OF SNOW.
COLD AIR WILL SURGE IN BEHIND THIS CLIPPER...AS THE POLAR VORTEX
DIVES SOUTHEAST TOWARDS JAMES BAY. AT THIS POINT IT LOOKS TO STAY
THERE...BUT IT WILL STILL LEAD TO H850 TEMPS IN THE LOW TO MID -20S.
WITH HIGH PRESSURE CENTERED IN THE CENTRAL PLAINS AND A LOW OVER
HUDSON BAY...EXPECT NORTHWESTERLY WINDS AT THE SURFACE AND THROUGH
H850. THIS WILL LEAD TO PERSISTENT LES IN THAT FAVORED WIND
DIRECTION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. WILL CONTINUE TO
HIGHLIGHT HIGH END LIKELY POPS IN THAT AREA. INTENSITY WILL DEPEND
ON THE INVERSION HEIGHTS AND IF ANY DEEPER MOISTURE OR SHORTWAVES
SWEEP THROUGH. 00Z GFS SHOWING LAKE INDUCED EQL HEIGHTS OF
7-9KFT...BUT MOISTURE REMAINS BELOW 5KFT WITH FORCING ON HIGHER
EDGE OF DGZ. THUS...POTENTIAL IS THERE FOR MODERATE SNOW...BUT
MOISTURE WILL BE CONTROLLING FACTOR.
GFS/ECMWF CONTINUING TO SHOW THE POTENTIAL FOR A WEAK SHORTWAVE
SLIDING THROUGH THE NORTHWEST FLOW ON FRIDAY AND AGAIN ON SATURDAY.
THIS LEADS TO SOME UNCERTAINTY IN THE LAKE EFFECT LOCATIONS AND
JUST LOW END CHANCE OR SLIGHT POPS ACROSS THE REST OF THE CWA.
AFTER A BELOW NORMAL START TO THE WORK WEEK...TEMPERATURES LOOK TO
RETURN TO NORMAL FOR TUESDAY/WEDNESDAY BEFORE FALLING 5-10 DEGREES
BELOW NORMAL FOR THE END OF THE WORK WEEK. FINALLY...00Z GFS HAS
TRENDED TOWARDS WHAT THE ECMWF HAS BEEN SHOWING WITH THE POLAR
VORTEX DIVING SOUTH INTO THE GREAT LAKES ON SUNDAY/MONDAY.
SIGNIFICANT DIFFERENCES IN THE AMOUNT OF COLD AIR BETWEEN THE
MODELS...SO IT WILL BE INTERESTING TO SEE WHICH ONE PANS OUT. IF
ECMWF IS RIGHT...H850 TEMPS WILL BE AROUND -35C AND WOULD LEAD TO
INLAND AREAS ON SLIGHTLY ABOVE ZERO FOR HIGHS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1213 AM EST SUN JAN 13 2013
EXPECT MVFR CONDITIONS TO PREVAIL AT CMX/IWD WITH SURGE OF COLD AIR
OVER THE RELATIVELY WARM WATERS OF LK SUP AND UPSLOPE W-NW WIND.
THERE COULD BE SOME HEAVIER SHSN/IFR CONDITIONS MAINLY AT CMX...
ESPECIALLY EARLY THIS MRNG WITH THE PASSAGE OF A LO PRES TROF. SINCE
THE W VEERING NW LLVL FLOW WL DOWNSLOPE AT SAW...EXPECT MVFR
CONDITIONS AT THAT LOCATION TO GIVE WAY TO VFR WX AT TIMES. THE
APPROACH OF ANOTHER DISTURBANCE LATER ON SUN WL INCREASE THE CHC OF
HEAVIER SHSN/IFR VSBYS AT IWD/CMX IN THE PRESENCE OF AN UPSLOPE
WIND. ALTHOUGH SOME -SHSN MAY IMPACT SAW AS WELL...DOWNSLOPE WIND WL
LIMIT THE POTENTIAL FOR ANY WORSE THAN MVFR CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 533 AM EST SUN JAN 13 2013
NORTHWEST WINDS ARE EXPECTED TO REMAIN AT OR BELOW 25 KNOTS THROUGH
MONDAY AS HIGH PRESSURE GRADUALLY BUILDS FROM THE PLAINS TOWARD THE
GREAT LAKES. A CLIPPER LOW PRES SYSTEM MOVING INTO SRN MANITOBA
TUESDAY AND NORTHERN ONTARIO TUE NIGHT WILL LIKELY BRING SW GALES
ACROSS LAKE SUPERIOR. AS THE LOW DEEPENS AND MOVES TOWARD NRN QUEBEC
WED...SOME NW GALES MAY ALSO BE POSSIBLE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM EST
MONDAY FOR MIZ006-007.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...KC
MARINE...JLB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
936 AM CST SUN JAN 13 2013
.DISCUSSION...
RECENT RADAR AND SURFACE OBSERVATION TRENDS SHOW A NICE BLOSSOMING
OF LIGHT SNOW ACTIVITY AHEAD OF THE MID-LEVEL TROUGH CURRENTLY
PUSHING ACROSS THE AREA. THIS FEATURE SHOWS UP WELL ON WATER
VAPOR... AND THE RUC HIGHLIGHTS A TIGHT UPPER LEVEL PV GRADIENT
ASSOCIATED WITH IT. GIVEN DEEP LAYER SATURATION AND SOME MODEST
VERTICAL MOTION EXPECT TO SEE OCCASIONAL LIGHT SNOW PERSIST AS THE
SYSTEM MOVES ACROSS THE AREA THROUGH THE DAY. PRECIPITATION
AMOUNTS WILL BE LIMITED... AND DON/T EXPECT MUCH MORE THAN A
DUSTING OR FEW TENTHS OF ACCUMULATION... BUT GIVEN THE FACT THAT
WHITE FROZEN STUFF WILL FALL FROM THE SKY DECIDED TO BUMP POPS UP
INTO THE LIKELY TO CATEGORICAL RANGE FOR LIGHT SNOW.
&&
.AVIATION.../12Z TAF ISSUANCE/
/ISSUED 503 AM CST SUN JAN 13 2013/
MAIN AVIATION CONCERN DEALS WITH MVFR CIGS AS BOUNDARY LAYER
MOISTURE...UP TO 70H IS RATHER HIGH...AND WITH THE TYPICAL DIURNAL
HEATING...WILL LIFT ANY MOISTURE TO THE LCL/S WHICH MEANS CIGS
DEVELOPING ARND 2-3K. IN ADDITION...MID LEVEL MOISTURE AND A
DISTURBANCE RIDING NE ACROSS IA WILL ENHANCE SOME LIFT ACROSS
EASTERN MN DURING THE DAY. SO...-SN REMAINS POSSIBLE BUT VSBYS
SHOULD NOT DROP BELOW MVFR AS ACTIVITY SHOULD BE ISOLATED. ANOTHER
AREA OF MVFR CIGS COULD BEGIN TO AFFECT THE TAFS AFT 6Z/14. WINDS
WILL REMAIN FROM THE NW/WNW THRU THE PERIOD WITH SPDS ARND 8-11
KTS TODAY...DROPPING OFF TO 4-6 KTS OVERNIGHT.
KMSP...
MVFR CIGS NEAR THE AIRPORT TERMINAL...BUT NOT WIDESPREAD ENOUGH TO
WARRANT IN CURRENT TAF...AT LEAST NOT UNTIL 15-16Z AS CIGS LOWER
TO 2.5K ALONG WITH -SN. BEST TIME PERIOD FOR FLURRIES WILL OCCUR
AFT 16Z...AND MAY LAST UNTIL 21-22Z. VFR CONDS SHOULD PREVAIL AFT
22Z...WITH SOME CONCERNS LATE IN THE TAF PERIOD OF MVFR CIGS
RETURNING AFT 6Z/14. WINDS WILL REMAIN FROM THE NW...THEN MORE WNW
OVERNIGHT. SPDS WILL BE ARND 8-10 KTS TODAY...DROPPING TO 4-7KTS
OVERNIGHT.
/OUTLOOK FOR KMSP/
MON...POSSIBLE MVFR CIGS EARLY. WINDS W 5-10 KTS.
TUE...VFR. WINDS SW AROUND 10 KTS...INCREASING TO 15-20 KTS TUE NIGHT.
WED...CHANCE MVFR OR LOWER CIGS/VIS WITH -SN. WINDS W 10G20KTS.
&&
.PREV DISCUSSION...
/ISSUED 400 AM CST SUN JAN 13 2013/
A MID/UPPER LEVEL TROUGH FROM ONTARIO TO THE CENTRAL PLAINS WILL
MOVE SLOWLY ACROSS THE FA TODAY. CURRENTLY THE CENTER PORTION OF
THE CWA IS CLEAR. HOWEVER... MID LEVEL CLOUDINESS IS EXPANDING
OVER EASTERN SD AND NE. BOTH THE NAM AND GFS SHOW THIS CLOUDINESS
SPREADING ENE THROUGH THE MORNING... WITH PARTLY TO MOSTLY CLOUDY
CONDITIONS OCCURRING. KEPT A MENTION OF FLURRIES TO THE NORTH AND
EAST OF THE TWIN CITIES TODAY WHERE LOW LEVEL CLOUDINESS ALREADY
EXISTS. IT WILL BE A COLD DAY WITH HIGHS IN THE SINGLE DIGITS TO
TEENS. HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT WITH
CLEARING OCCURRING. LOWS ARE FORECAST FROM ZERO TO 10 BELOW.
THE WEEK AHEAD WILL FEATURE A SERIES OF ALBERTA CLIPPER LOW
PRESSURE SYSTEMS. TIMING AND LOCATION ARE IN PRETTY GOOD AGREEMENT
BETWEEN THE GFS AND ECMWF. THE FIRST WILL PASS ALONG OR JUST NORTH
OF THE INTERNATIONAL BORDER TUESDAY NIGHT AND EARLY WEDNESDAY.
THE SREF IS ALREADY SHOWING LIKELY TO CATEGORICAL POPS FOR THE
NORTHERN HALF OF MN AND WI. AT THIS POINT...BLENDED IN THE SREF
WHICH BROUGHT OUR POPS UP INTO THE HIGH CHANCE CATEGORY ACROSS
OUR FAR NORTHERN CWA. SOME LIGHT SNOW ACCUMULATION WOULD CERTAINLY
BE POSSIBLE ALONG AND NORTH OF I-94.
THE COLD FRONT TRAILING THE LOW WILL MOVE THROUGH LATE ON
WEDNESDAY. THIS ALLOWS ANOTHER WEAK LOW TO MOVE ALONG THIS
BOUNDARY THURSDAY NIGHT AND FRIDAY. THIS EVENT IS AGAIN MAINLY
ALONG AND NORTH OF I-94...BUT IT DOES HAVE THE POSSIBILITY OF
GETTING DOWN INTO THE TWIN CITIES FOR THE FRIDAY MORNING COMMUTE
AND WILL NEED TO BE WATCHED.
FINALLY...ANOTHER LOW WILL PASS ALONG THE INTERNATIONAL BORDER
FRIDAY NIGHT AND SATURDAY WITH A PRECIPITATION PATTERN EXPECTED
MUCH LIKE THE TUESDAY NIGHT/WEDNESDAY ONE. ONE THING NOTED IS THAT
THERE WILL BE A PRETTY WARM WESTERLY FLOW ACROSS SOUTHERN MN AND
INTO WI WITH THE SATURDAY LOW PRESSURE SYSTEM AND HIGH
TEMPERATURES IN THE 25 TO 30 DEGREE RANGE MAY NOT BE WARM
ENOUGH...ESPECIALLY WHEN COMPARING THE LOW LEVEL THERMAL PATTERN
FOR WEDNESDAY WITH 35 TO 40 DEGREE TEMPERATURES PROGGED.
IT DOES APPEAR THAT IN THE WAKE OF NEXT WEEKENDS LOW PRESSURE
SYSTEM...THE FLOW PATTERN ALOFT WILL TURN NORTHERLY. THIS COULD
UNLEASH THE COLDEST AIR YET THIS WINTER. ITS POSSIBLE WE COULD SEE
A DAY OR TWO WHERE THE HIGH FAILS TO GET ABOVE ZERO...ESPECIALLY
ACROSS THE CENTRAL AND NORTH WHERE A BETTER SNOW-PACK STILL EXISTS
AND MORE COULD BE ADDED THIS WEEK. THIS COULD ALSO JEOPARDIZE THE
RECORD HERE AT MSP WHERE CONSECUTIVE DAYS WITH HIGHS OF ZERO OR
GREATER HAVE OCCURRED FOR NEARLY 4 YEARS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
556 AM CST SUN JAN 13 2013
.SHORT TERM...
ISSUED AT 502 AM CST SUN JAN 13 2013
(TODAY)
THERE ARE TWO MAIN AREAS OF CONCERN WRT PCPN TODAY. THE FIRST IS
NEAR THE FNTL BDRY WHICH MOVED THROUGH THE CWA YESTERDAY AND THE
SECOND IS AN AREA OF FRONTOGENESIS ALONG THE VERTICALLY SLOPED
FRONTAL SFC WHICH IS FCST TO MOVE THROUGH THE CWA TODAY.
A VORT MAX IN THE BASE OF THE LONGWAVE TROF OVER OK/TX IS FCST TO
LIFT NEWD INTO WISCONSIN TODAY WHICH WILL PROVIDE A SOURCE OF LARGE
SCALE LIFT ACROSS THE AREA AS SEEN ON H7-H5 QVECTOR CONVERGENCE
GRAPHICS. A STRONG CDFNT WAS LOCATED SOUTHEAST OF THE CWA EARLY
THIS MORNING AND A SFC WAVE RIDING ALONG THE BDRY OVERNIGHT HAD
PUSHED IT EVEN FARTHER TO THE SOUTHEAST. WIDESPREAD PCPN WAS ALSO
OCCURRING ALONG THE FRONT EARLY THIS MORNING. ANOTHER SFC WAVE IS
FCST TO RIDE NEWD ALONG THE BAROCLINIC ZONE TODAY AND SOME OF THE
FNTL PCPN COULD SPILL OVER INTO THE SERN AND ERN CWA
TODAY...ESPECIALLY IF A PORTION OF THE SFC BDRY LIFTS SLIGHTLY
NWWD AHEAD OF THE SFC WAVE. THE CONCERN HERE IS THAT TEMPERATURE
PROFILES WOULD SUPPORT FREEZING RAIN OVER THIS AREA. THERE ARE NO
STRONG SIGNALS IN THE MODELS TO SUPPORT SUCH A NWWD WOBBLE BUT IF
IT DOES OCCUR OR IF SCT SHRA /SIMILAR TO WHAT WAS OCCURRING OVER
AR BETWEEN 10-11Z/ EXPANDS IN COVERAGE THEN LATER SHIFTS MAY NEED
TO CONSIDER A FREEZING RAIN ADVISORY FOR PARTS OF THE SERN/ERN
CWA.
THE SECOND AREA OF CONCERN WAS A BAND OF FRONTOGENETICALLY FORCED
PCPN OVER NERN OK/SERN KS/WRN MO WHICH APPEARED TO BE OCCURRING
ALONG THE H85-H7 FRONTAL SFC BASED ON THE 09Z RUC ANALYSIS. THIS
AREA OF FORCING IS EXPECTED TO EXPAND/MOVE ACROSS THE CWA TODAY
WITH THE LIFTING VORT MAX AND COULD RESULT IN LIGHT SNOW OR LIGHT
FREEZING RAIN/DRIZZLE SINCE THE FCST FORCING AND MOISTURE OVER OUR
AREA LATER TODAY BOTH LOOK COMPARABLE TO WHAT WAS ALREADY
OCCURRING OVER OK BETWEEN 09-11Z. IN SUMMARY...THE GREATEST
POTENTIAL FOR MEASURABLE -FZRA IS OVER THE SERN/ERN CWA AND A
TRACE OF GLAZING IS POSSIBLE ELSEWHERE. WE WILL ISSUE AN SPS TO
HIGHLIGHT THE POTENTIAL FOR A LIGHT GLAZE SINCE EVEN TRACE AMOUNTS
OF FREEZING RAIN/DRIZZLE CAN BE HAZARDOUS.
TEMPERATURES WILL PROBABLY STRUGGLE TO RISE MUCH ABOVE FREEZING
TODAY IN MOST LOCATIONS DUE TO THE COLD AIR MASS IN PLACE AND
WIDESPREAD CLOUDINESS DURING MOST OF THE DAYLIGHT HOURS.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 210 AM CST SUN JAN 13 2013
(TONIGHT - TUESDAY NIGHT)
SW UPPER LEVEL FLOW WILL PREVAIL ACROSS THE REGION DURING THIS TIME
WITH A WEAK UPPER LEVEL DISTURBANCE MOVING THRU MONDAY AND THE
HEAVILY SHEARED REMNANTS FROM THE LONGWAVE TROF BASE ON TUESDAY AND
TUESDAY NIGHT. WHILE THIS PATTERN ALONE MAY TRY TO GIVE THE
SEMBLANCE OF AN ACTIVE PATTERN WITH ADDITIONAL CHANCES FOR PCPN...
THE SFC PATTERN WILL ALL BUT SQUASH THAT...WITH HI PRES DOMINATING
UNDERNEATH AND MAINTAINING VERY DRY AIR THRU THE COLUMN.
THE SFC HI THAT WILL DOMINATE THIS PERIOD WILL ALSO KEEP US BELOW
AVERAGE...ABOUT 10 DEGREES BELOW ON MONDAY AND 5 DEGREES BELOW ON
TUESDAY...AS THE AIRMASS SLOWLY MODERATES. MOS LOOKS A BIT TOO COLD
FOR MAXES BOTH DAYS...PERHAPS FROM OVERESTIMATING/ANTICIPATING SNOW
COVER FROM YESTERDAY/S SYSTEM...AND LEANED WARM VERSUS THEM.
(WEDNESDAY - SATURDAY)
A BIT OF A PATTERN SHIFT OF SOME NOTE OCCURS EARLY IN THIS PERIOD
WITH LONGWAVE TROF SHIFTING TO THE ERN CONUS...ALBEIT NOT QUITE WHAT
IT WAS WHEN IT WAS OVER THE W...AND IS ANTICIPATED TO BE GREATLY
DE-AMPLIFIED. THIS WILL GIVE US A W-NW FLOW AND IS EXPECTED TO BE
MARKED BY LITTLE OR NO WX-MAKING DISTURBANCES OF NOTE AND TEMPS AT
OR ABOVE AVERAGE.
ONCE WE GET IN THIS PATTERN...IT LOOKS LIKE IT WILL STAY FOR A WHILE
AS VERY LATE IN THIS PERIOD AMPLIFICATION OF THE RIDGE WILL TAKE
PLACE OVER THE WRN CONUS AND THIS WILL CAUSE A CORRESPONDING
DEEPENING OF THE TROF IN THE E. IF THIS HOLDS...SEVERAL WAVES OF
NOTABLE COLD COULD COME OUT OF THIS. BUT IF YOU ARE LOOKING FOR
SNOW...SYSTEMS TO TAKE ADVANTAGE OF THIS APPEAR SCARCE.
TES
&&
.AVIATION...
ISSUED AT 534 AM CST SUN JAN 13 2013
MVFR CIGS WILL GRADUALLY RISE THROUGH THE DAY WITH VFR CONDITIONS
EXPECTED BY EARLY EVENING. THE EXCEPTION TO THE OVERALL
IMPROVING TREND IS A BAND OF LIGHT TO MODERATE SNOW WHICH HAS
DVLPD OVER SWRN AND CENTRAL MO. IT LOOKS LIKE THIS BAND WILL REACH
KCOU/KUIN WITHIN THE NEXT FEW HOURS. IT IS NOT YET CLEAR IF THE
BAND WILL REACH KSUS/KCPS. EXPECT AROUND AN HOUR OF LIGHT TO
MODERATE SNOW WITH MVFR TO IFR VSBYS IF THE BAND MOVES OVER ONE OF
THE TERMINALS.
SPECIFICS FOR KSTL...MVFR CIGS ARE EXPECTED TO PERSIST FOR MOST OF
THE DAY BEFORE CLEARING LATE THIS AFTN OR EARLY THIS EVENING.
THERE COULD BE A BRIEF PD OF FREEZING DRIZZLE OR SNOW AT KSTL
TODAY BUT CONFIDENCE WAS TOO LOW TO INCLUDE A MENTION OF EITHER
PTYPE IN THE 12Z TAF. PCPN CHCS ARE TIED TO BOTH THE BAND OF SNOW
THAT WAS OVER SWRN/CENTRAL MO AT 12Z AND THE BROAD AREA OF
RAINFALL THAT WAS LOCATED ACROSS SERN MO NEAR A STRONG COLD
FRONT. MOST OF THE PCPN ASSOCIATED WITH THE COLD FRONT SHOULD
REMAIN WELL TO THE SOUTH AND EAST OF KSTL BUT SCT SHRA HAVE
RECENTLY DEVELOPED OVER ARKANSAS AND WERE MOVING NEWD. BUFKIT
PROFILES SUPPORT FREEZING DRIZZLE/RAIN IF THESE SHOWERS WERE TO
REACH KSTL. AS FOR THE SNOW...IT IS NOT YET CLEAR WHETHER THE BAND
OF SNOW IN SWRN/CENTRAL MO WILL REACH KSTL. IF IT DOES THEN THERE
WOULD BE AROUND AN HOUR OF LIGHT TO MODERATE SNOW WITH MVFR TO IFR
VSBYS BASED ON UPSTREAM OBS.
KANOFSKY
&&
.PRELIMINARY POINT TEMPS/POPS...
ST LOUIS 29 16 29 18 / 20 0 0 0
QUINCY 25 10 26 13 / 10 0 0 0
COLUMBIA 26 11 29 14 / 10 0 0 0
JEFFERSON CITY 28 11 29 14 / 10 0 0 0
SALEM 33 15 30 17 / 40 5 5 0
FARMINGTON 32 14 32 15 / 20 0 5 0
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
506 AM CST SUN JAN 13 2013
.SHORT TERM...
ISSUED AT 502 AM CST SUN JAN 13 2013
(TODAY)
THERE ARE TWO MAIN AREAS OF CONCERN WRT PCPN TODAY. THE FIRST IS
NEAR THE FNTL BDRY WHICH MOVED THROUGH THE CWA YESTERDAY AND THE
SECOND IS AN AREA OF FRONTOGENESIS ALONG THE VERTICALLY SLOPED
FRONTAL SFC WHICH IS FCST TO MOVE THROUGH THE CWA TODAY.
A VORT MAX IN THE BASE OF THE LONGWAVE TROF OVER OK/TX IS FCST TO
LIFT NEWD INTO WISCONSIN TODAY WHICH WILL PROVIDE A SOURCE OF LARGE
SCALE LIFT ACROSS THE AREA AS SEEN ON H7-H5 QVECTOR CONVERGENCE
GRAPHICS. A STRONG CDFNT WAS LOCATED SOUTHEAST OF THE CWA EARLY
THIS MORNING AND A SFC WAVE RIDING ALONG THE BDRY OVERNIGHT HAD
PUSHED IT EVEN FARTHER TO THE SOUTHEAST. WIDESPREAD PCPN WAS ALSO
OCCURRING ALONG THE FRONT EARLY THIS MORNING. ANOTHER SFC WAVE IS
FCST TO RIDE NEWD ALONG THE BAROCLINIC ZONE TODAY AND SOME OF THE
FNTL PCPN COULD SPILL OVER INTO THE SERN AND ERN CWA
TODAY...ESPECIALLY IF A PORTION OF THE SFC BDRY LIFTS SLIGHTLY
NWWD AHEAD OF THE SFC WAVE. THE CONCERN HERE IS THAT TEMPERATURE
PROFILES WOULD SUPPORT FREEZING RAIN OVER THIS AREA. THERE ARE NO
STRONG SIGNALS IN THE MODELS TO SUPPORT SUCH A NWWD WOBBLE BUT IF
IT DOES OCCUR OR IF SCT SHRA /SIMILAR TO WHAT WAS OCCURRING OVER
AR BETWEEN 10-11Z/ EXPANDS IN COVERAGE THEN LATER SHIFTS MAY NEED
TO CONSIDER A FREEZING RAIN ADVISORY FOR PARTS OF THE SERN/ERN
CWA.
THE SECOND AREA OF CONCERN WAS A BAND OF FRONTOGENETICALLY FORCED
PCPN OVER NERN OK/SERN KS/WRN MO WHICH APPEARED TO BE OCCURRING
ALONG THE H85-H7 FRONTAL SFC BASED ON THE 09Z RUC ANALYSIS. THIS
AREA OF FORCING IS EXPECTED TO EXPAND/MOVE ACROSS THE CWA TODAY
WITH THE LIFTING VORT MAX AND COULD RESULT IN LIGHT SNOW OR LIGHT
FREEZING RAIN/DRIZZLE SINCE THE FCST FORCING AND MOISTURE OVER OUR
AREA LATER TODAY BOTH LOOK COMPARABLE TO WHAT WAS ALREADY
OCCURRING OVER OK BETWEEN 09-11Z. IN SUMMARY...THE GREATEST
POTENTIAL FOR MEASURABLE -FZRA IS OVER THE SERN/ERN CWA AND A
TRACE OF GLAZING IS POSSIBLE ELSEWHERE. WE WILL ISSUE AN SPS TO
HIGHLIGHT THE POTENTIAL FOR A LIGHT GLAZE SINCE EVEN TRACE AMOUNTS
OF FREEZING RAIN/DRIZZLE CAN BE HAZARDOUS.
TEMPERATURES WILL PROBABLY STRUGGLE TO RISE MUCH ABOVE FREEZING
TODAY IN MOST LOCATIONS DUE TO THE COLD AIR MASS IN PLACE AND
WIDESPREAD CLOUDINESS DURING MOST OF THE DAYLIGHT HOURS.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 210 AM CST SUN JAN 13 2013
(TONIGHT - TUESDAY NIGHT)
SW UPPER LEVEL FLOW WILL PREVAIL ACROSS THE REGION DURING THIS TIME
WITH A WEAK UPPER LEVEL DISTURBANCE MOVING THRU MONDAY AND THE
HEAVILY SHEARED REMNANTS FROM THE LONGWAVE TROF BASE ON TUESDAY AND
TUESDAY NIGHT. WHILE THIS PATTERN ALONE MAY TRY TO GIVE THE
SEMBLANCE OF AN ACTIVE PATTERN WITH ADDITIONAL CHANCES FOR PCPN...
THE SFC PATTERN WILL ALL BUT SQUASH THAT...WITH HI PRES DOMINATING
UNDERNEATH AND MAINTAINING VERY DRY AIR THRU THE COLUMN.
THE SFC HI THAT WILL DOMINATE THIS PERIOD WILL ALSO KEEP US BELOW
AVERAGE...ABOUT 10 DEGREES BELOW ON MONDAY AND 5 DEGREES BELOW ON
TUESDAY...AS THE AIRMASS SLOWLY MODERATES. MOS LOOKS A BIT TOO COLD
FOR MAXES BOTH DAYS...PERHAPS FROM OVERESTIMATING/ANTICIPATING SNOW
COVER FROM YESTERDAY/S SYSTEM...AND LEANED WARM VERSUS THEM.
(WEDNESDAY - SATURDAY)
A BIT OF A PATTERN SHIFT OF SOME NOTE OCCURS EARLY IN THIS PERIOD
WITH LONGWAVE TROF SHIFTING TO THE ERN CONUS...ALBEIT NOT QUITE WHAT
IT WAS WHEN IT WAS OVER THE W...AND IS ANTICIPATED TO BE GREATLY
DE-AMPLIFIED. THIS WILL GIVE US A W-NW FLOW AND IS EXPECTED TO BE
MARKED BY LITTLE OR NO WX-MAKING DISTURBANCES OF NOTE AND TEMPS AT
OR ABOVE AVERAGE.
ONCE WE GET IN THIS PATTERN...IT LOOKS LIKE IT WILL STAY FOR A WHILE
AS VERY LATE IN THIS PERIOD AMPLIFICATION OF THE RIDGE WILL TAKE
PLACE OVER THE WRN CONUS AND THIS WILL CAUSE A CORRESPONDING
DEEPENING OF THE TROF IN THE E. IF THIS HOLDS...SEVERAL WAVES OF
NOTABLE COLD COULD COME OUT OF THIS. BUT IF YOU ARE LOOKING FOR
SNOW...SYSTEMS TO TAKE ADVANTAGE OF THIS APPEAR SCARCE.
TES
&&
.AVIATION...
ISSUED AT 1027 PM CST SAT JAN 12 2013
LOOKING AT THE LATEST RADAR LOOP MUCH OF THE SIGNIFICANT
PRECIPITATION SHOULD SHIFT E OF THE TAF SITES BY 06Z SUN OR
SHORTLY THEREAFTER. LIGHT SNOW SHOULD TAPER OFF TO FLURRIES IN UIN
AND COU LATE TGT...WHILE LIGHT RAIN AND LIGHT FREEZING RAIN
CHANGES TO MAINLY FREEZING DRIZZLE IN THE ST LOUIS METRO AREA LATE
TGT AND CONTINUES INTO EARLY SUN MRNG. MAY SEE SOME IMPROVEMENT IN
THE CLOUD CEILING HEIGHT IN UIN AND COU ALREADY LATE TGT WITH
MAINLY MVFR CONDITIONS EXPECTED. IN THE ST LOUIS METRO AREA THE
CEILING HEIGHT SHOULD VARY BETWEEN MVFR AND IFR LATE TGT INTO SUN
MRNG. WILL SEE IMPROVEMENT IN THE CEILING HEIGHT ON SUN AS THE
SFC RIDGE OVER THE NRN PLAINS BUILDS SEWD INTO MO WITH VFR
CONDITIONS IN UIN AND COU IN THE AFTN AND VFR CONDITIONS IN THE
ST LOUIS METRO AREA BY LATE SUN AFTN OR EARLY EVNG. NWLY SFC WINDS
WILL CONTINUE LATE TGT AND SUN...DIMINISHING SUN NGT AS THE SFC
PRESSURE GRADIENT RELAXES.
SPECIFICS FOR KSTL...THE FREEZING RAIN WILL TAPER OFF TO FREEZING
DRIZZLE LATE TGT AS THE COLD FRONT EXTENDING FROM IN SW THROUGH
THE MO BOOTHEEL AND AR CONTINUES TO SHIFT FURTHER SEWD. THERE MAY
ALSO BE FLURRIES SUN MRNG AS THE COLD AIR DEEPENS OVER THE AREA.
THE CEILING HEIGHT SHOULD HOVER AROUND 1000 FT LATE TGT...THEN
GRADUALLY IMPROVE DURING THE DAY ON SUN...AND SCATTER OUT BY LATE
SUN AFTN OR EARLY SUN EVNG. THE NWLY SFC WIND WILL CONTINUE...
EVENTUALLY DIMINISHING SUN NGT.
GKS
&&
.PRELIMINARY POINT TEMPS/POPS...
ST LOUIS 29 16 29 18 / 20 0 0 0
QUINCY 25 10 26 13 / 10 0 0 0
COLUMBIA 26 11 29 14 / 10 0 0 0
JEFFERSON CITY 28 11 29 14 / 10 0 0 0
SALEM 33 15 30 17 / 40 5 5 0
FARMINGTON 32 14 32 15 / 20 0 5 0
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
835 AM CST SUN JAN 13 2013
.UPDATE...
LATEST RADAR TRENDS SHOWED CLEARING SKIES AND THUS NO NEED FOR A
-SN MENTION ACROSS THE NORTHEASTERN SOUTH PLAINS. HAVE THEREFORE
UPDATED THE FORECAST TO REFLECT THIS CHANGE.
&&
.PREV DISCUSSION... /ISSUED 556 AM CST SUN JAN 13 2013/
AVIATION...
MVFR CIGS IN PLACE AT KLBB ARE EXPECTED TO SCATTER OUT BY MID-
MORNING...THOUGH THERE IS A LOW CHANCE THEY COULD HANG IN PLACE
INTO THE AFTERNOON. KCDS IS CURRENTLY EXPERIENCING VFR CIGS AND
THINK THIS IS WHERE THEY WILL STAY. HOWEVER...A WEAKENING BAND OF
SNOW APPROACHING KCDS FROM THE WEST COULD BRIEFLY CAUSE CIGS TO
LOWER TO NEAR MVFR LEVELS...PERHAPS EVEN SUPPLYING A FEW FLURRIES
OR LIGHT SNOW SHOWERS...THOUGH NO IMPACTS ARE EXPECTED.
OTHERWISE...HAVE VFR CONDITIONS IN PLACE AT THE TERMINALS THIS
AFTERNOON AND TONIGHT WITH NORTHERLY WINDS THIS MORNING VEERING TO
EASTERLY BY MIDDAY AT KLBB AND BY THIS EVENING AT KCDS. THE
UPSLOPE FLOW RAISES SOME CONCERN THAT LOW CLOUDS COULD
REDEVELOP TONIGHT...THOUGH CURRENT GUIDANCE ARGUES AGAINST THIS
WITH RELATIVELY DRY AIR IN PLACE.
PREV DISCUSSION... /ISSUED 354 AM CST SUN JAN 13 2013/
SHORT TERM...
A SPRAWLING AND COMPLEX UPPER LEVEL TROUGH WAS DOMINATING THE
WESTERN 2/3RDS OF THE CONUS...WITH SEVERAL EMBEDDED DISTURBANCES
NOTED WITHIN IT. ONE SUCH SHORTWAVE TROUGH WAS GRAZING THE AREA
EARLY THIS MORNING...WITH ANOTHER CURRENTLY DIVING DOWN THE SOUTHERN
CALIFORNIA COAST PROGGED TO APPROACH FROM THE WEST LATE TONIGHT. THE
FORMER HAS PROVIDED STRONG ENOUGH LIFT TO PRODUCE A BAND OF SNOW
THAT HAS TRAVERSED THE NORTHWEST AND NORTH-CENTRAL ZONES EARLY THIS
MORNING. EVEN THOUGH THE PRESENTATION ON RADAR WITHIN THIS BAND HAS
NOT BEEN OVERLY IMPRESSIVE AND MOISTURE IS RATHER LIMITED...THE BAND
HAS BEEN ABLE TO SQUEEZE OUT EFFICIENT SNOW RATES GIVEN THE COLD
TEMPERATURES AND HIGH SNOW TO LIQUID RATIOS. FRIONA REPORTED A QUICK
1-2 INCHES OF SNOW AS THE BAND MOVED THROUGH EARLIER THIS
MORNING...WITH DIMMITT AND TULIA REPORTING LESS THAN 1 INCH. LIFT
SUPPORTING THIS BAND WILL GRADUALLY WANE MOVING TOWARDS
DAYBREAK...BUT A LITTLE LIGHT SNOW OR FLURRIES COULD LINGER PAST 12Z
ACROSS THE NORTHEAST ZONES.
OTHERWISE...COLD SFC RIDGING WILL DOMINATE THE REGION THROUGH THE
SHORT TERM. LOW STRATUS CLOUDS HAVE DEVELOPED ACROSS ROUGHLY THE
NORTHWEST HALF OF THE CWA IN THIS REGIME EARLY THIS MORNING. BOTH
THE NAM AND GFS SUGGEST THESE CLOUDS WILL QUICKLY SCATTER OUT THIS
MORNING AS MID- AND UPPER-LEVEL SUBSIDENCE INCREASES IN THE WAKE OF
THE PASSING SHORTWAVE TROUGH. ON THE OTHER HAND...THE RUC AND HRRR
SUGGEST THAT THE LOW CLOUDS MAY HANG ON MUCH OR ALL OF THE DAY ON
THE CAPROCK AS WINDS VEER EASTERLY AND THE SHALLOW BUT RELATIVELY
MOIST UPSLOPE FLOW ENSUES. CURRENT FORECAST IN THE GRIDS DOES
INDICATE CLEARING SKIES BY MIDDAY...BUT IF THIS DOES NOT
OCCUR...FORECAST HIGHS WILL LIKELY BE TOO HIGH. REGARDLESS...IT WILL
BE A CHILLY DAY AND HAVE FAVORED THE LOW SIDE OF MOS GUIDANCE WITH
FORECAST HIGHS IN THE LOWER TO MIDDLE 30S FOR ALL BUT THE NORTHWEST
ZONES WHERE UPPER 20S WERE CARRIED.
CHILLY EASTERLY UPSLOPE FLOW WILL CONTINUE THROUGH TONIGHT. PROGGED
SOUNDINGS INDICATE MOSTLY CLEAR SKIES EARLY ON...WITH SOME MID-LEVEL
CLOUDS VISITING AT LEAST THE NORTHWEST ZONES LATE AS THE NEXT
SHORTWAVE TROUGH RACES BY. HOWEVER...GIVEN THE UPSLOPE FLOW WOULD
NOT BE SURPRISED IF SOME LOWER CLOUDS DEVELOP OR PERSIST. ALTHOUGH
MODELS ARE GENERALLY DRY...THINK THERE MAY BE ENOUGH LIFT AND
MOISTURE TO SQUEEZE OUT A FEW FLURRIES ACROSS THE WESTERN ZONES LATE
TONIGHT AND HAVE INSERTED THIS INTO THE FORECAST. EXTENT AND
DURATION OF ANY CLOUD COVER COULD HAVE SOME IMPACTS ON EXACTLY HOW
COLD IT GETS TONIGHT...BUT EITHER WAY IT WILL BE CHILLY AND HAVE
MAINTAINED LOWS 10-15 DEGREES BELOW MID-JANUARY AVERAGES /RANGING
FROM 9 DEGREES NORTHWEST TO MID-TEENS OUT EAST/.
LONG TERM...
THE MON THRU THU FORECAST HINGES ON THE STRENGTH AND TRACK OF THE
SRN PORTION OF THE UPPER-LEVEL TROUGH...INITIALLY LOCATED OVER AZ
AND NM MONDAY MORNING. THE MAJORITY OF GUIDANCE ELONGATES THE TROUGH
FROM THE SW TO NE AS IT SLIDES SEWD ACROSS WEST TEXAS...WITH
MOISTURE AND LIFT BOTH LACKING TO WRING OUT ANY PRECIPITATION FOR
OUR AREA...BEFORE IT EVENTUALLY CLOSES OFF AT 500 MB ACROSS NORTH
CENTRAL TX. HOWEVER...THERE ARE STILL A FEW MODELS /E.G. 0Z NAM
AND CMC/ AND SOME GEFS ENSEMBLE MEMBERS THAT CLOSED OFF TROUGH
INTO A CUTOFF LOW ACROSS SRN NM OR NRN MX...THEN TRACK IT SLOWLY
EAST ACROSS WEST TEXAS MID-WEEK. IN THE LATTER CASE COULD BRING
A CHANCE OF SOME RAIN OR SNOW IN THE TUE THRU THU TIME FRAME AS
BOTH MOISTURE ADVECTION AND LIFT WOULD BE ENHANCED. BUT
PREPONDERANCE OF GUIDANCE SUGGESTS THE OPEN WAVE PASSAGE
ACCOMPANIED BY ONLY AN INCREASE IN MID-LVL CLOUD COVER. THUS WE/VE
KEPT POPS BELOW MENTION THROUGH THE EXTENDED PERIOD...ALTHOUGH
NUDGED THEM UP TO 10 PERCENT ACROSS OUR SRN ZONES. MONDAY STILL
APPEARS TO BE THE COOLEST DAY IN THE PERIOD...WITH HIGHS ONLY IN
THE LOW TO MID 30S. TUESDAY WILL ONLY BE SLIGHTLY WARMER...WITH
HIGHS IN THE UPPER 30S TO LOW 40S. FINALLY...BARRING THE CLOSED
LOW SOLUTION...HIGHS WILL WARM BACK INTO THE UPPER 40S AND 50S WED
AND THU.
FRI-SAT: AFTER THE TROUGH/LOW PASSES...WEAK ZONAL TO SW FLOW SHOULD
EXTEND OVER THE AREA AS A BROAD LOW-AMPLITUDE TROUGH DEVELOPS OVER
THE DESERT SOUTHWEST. SOME SUB-TROPICAL MOISTURE MAY GET DRAWN UP BY
THE TROUGH TO BRING SOME HIGH CLOUD COVER TO THE AREA BY FRIDAY. AND
JUST TO OUR NORTH...UPPER FLOW WILL BECOME CYCLONIC AS A DEEP
TROUGH DROPS INTO THE GREAT LAKES REGION...WHILE THE UPPER RIDGE
RE-AMPLIFIES ALONG THE PACIFIC COAST. TEMPS WILL CONTINUE TO BE
MILD WITH HIGHS MAINLY IN THE MID TO UPPER 50S.
A WEAK FRONT IS EXPECTED TO MOVE INTO THE AREA BY SUNDAY...RESULTING IN
A MODEST COOL DOWN DEPENDING ON THE TIMING OF THE FROPA. A MUCH
STRONGER FRONT IS POSSIBLE BY MONDAY THE 21ST...AS A 1050MB SFC RIDGE
DIVES OUT OF CENTRAL CANADA INTO THE PLAINS. IT IS STILL TOO EARLY
TO TELL IF THIS COLD AIR MASS WILL SETTLE INTO WEST TEXAS OR IF
WE/LL ONLY RECEIVE A GLANCING BLOW.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 28 9 29 9 37 / 10 10 10 10 10
TULIA 29 10 30 12 38 / 0 0 10 10 10
PLAINVIEW 31 11 31 11 38 / 10 10 10 10 10
LEVELLAND 34 11 32 12 38 / 10 10 10 10 10
LUBBOCK 33 12 33 13 39 / 10 10 0 10 10
DENVER CITY 36 13 32 12 38 / 10 10 10 10 10
BROWNFIELD 36 12 32 13 38 / 10 10 0 10 10
CHILDRESS 35 15 34 15 41 / 0 0 0 0 10
SPUR 35 14 34 15 40 / 0 0 0 0 10
ASPERMONT 37 16 36 14 41 / 0 0 10 0 10
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
29
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
519 AM CST SUN JAN 13 2013
.AVIATION...
/12Z TAFS/
VFR CONDITIONS GENERALLY PREVAIL ACROSS NORTH TEXAS AS LOW LEVELS
CONTINUE TO DRY OUT. BKN/OVC CONDS WITH CIGS AROUND 8000FT ARE
EXPECTED TO PERSIST FOR THE NEXT SEVERAL HOURS. FORCING FROM
STRONG TROUGH TO THE WEST AND AVAILABLE MID LEVEL MOISTURE ARE
RESULTING IN CONTINUED SCATTERED ELEVATED CONVECTION GENERALLY
EAST OF THE MAJOR AIRPORTS. SMALL HAIL AND A FEW LIGHTNING STRIKES
WILL ACCOMPANY THIS ACTIVITY THROUGH MID MORNING. OTHERWISE...THE
STRONG NORTH WINDS WILL PERSIST THROUGHOUT THE DAY BEFORE
DIMINISHING TONIGHT. VFR CONDITIONS EXPECTED TO PREVAIL ON MONDAY.
DUNN
&&
.PREV DISCUSSION... /ISSUED 425 AM CST SUN JAN 13 2013/
SHORT TERM WINTER WEATHER/FORECAST CONCERNS...
DID NOT MAKE ANY SIGNIFICANT CHANGES TO THE FORECAST FROM THE 139
AM CST FORECAST UPDATE/AFD. THERE IS STILL NO MODEL GUIDANCE THAT
HAS A GOOD HANDLE ON WINTRY PRECIPITATION FALLING NORTHWEST OF THE
METROPLEX EARLY THIS MORNING. THE HRRR IS CLOSEST...BUT DOESNT
SEEM TO KNOW WHAT IS CAUSING THE WINTRY PRECIPITATION. THE HRRR
CONSISTENTLY INITIALIZES THE RADAR RETURNS AND THEN ALLOWS THEM TO
DISSIPATE SHORTLY THEREAFTER WHICH IS A GOOD SIGN THAT THE MODEL
IS NOT RESOLVING THE FORCING MECHANISM THAT IS RESPONSIBLE FOR THE
PRESENCE OF THE PRECIPITATION. AT ANY RATE...DRAWING BACK ON
MORNING UPDATE DISCUSSIONS...THE GFS FORECAST THAT H700 CONFLUENCE
WOULD DISSIPATE EARLY THIS MORNING SEEMS TO BE SPOT ON ACCORDING
TO REGIONAL VWP OUTPUT. THE BEST H700 CONFLUENCE HAD MOVED NORTH
OF THE RED RIVER AS OF 09Z...AND LIGHT WINTRY PRECIPITATION WAS
LIFTING NORTHEAST AS WELL. THERE IS STILL SOME CONCERN FOR H800
FRONTOGENETIC FORCING ALONG A SHERMAN TO FORT WORTH TO GRANBURY
LINE AROUND SUNRISE RESULTING IN SOME SHALLOW CONVECTION
INITIATION. THE GFS CONTINUES TO ADVERTISE THIS FORCING FOR
ASCENT NEAR THE H800 LEVEL WITH A 100 MB LAYER ABOVE IT
CHARACTERIZED BY DECREASING THETA-E TEMPERATURES WITH
HEIGHT (ESSENTIALLY POSITIVE CAPE).
THAT SAID...THERE IS NO OBSERVATIONAL EVIDENCE THAT STRONG LIFT IS
OCCURRING AT THIS TIME AS THERE ARE NO RAPIDLY COOLING CLOUD TOPS
OR LIGHT MID-LEVEL RADAR REFLECTIVITY RETURNS OVER THESE AREAS AT
THE TIME OF THIS DISCUSSION. THEREFORE WILL NOT BE ISSUING A
FREEZING RAIN ADVISORY FROM SHERMAN...THROUGH THE DFW METROPLEX
AND SOUTHWEST TOWARDS GRANBURY AT THIS TIME. OF COURSE WE WILL
CONTINUE TO MONITOR THIS SITUATION CLOSELY THROUGH SUNRISE AS ANY
DEVELOPING PRECIPITATION WILL LIKELY BE COMPOSED OF SUPERCOOLED
WATER. WHILE THIS WOULD FALL IN LIQUID FORM...IT WOULD FREEZE
IMMEDIATELY UPON CONTACT WITH ANY SURFACE THAT IS ALSO AT OR BELOW
FREEZING. AT THIS TIME IT LOOKS AS THOUGH MOST PRECIPITATION
DEVELOPMENT WILL REMAIN SOUTHEAST OF THIS LINE THROUGH
SUNRISE...DIMINISHING THE THREAT FOR FREEZING RAIN OR SLEET.
TODAY THROUGH MONDAY...ALL GUIDANCE INDICATES THAT LOW-LEVEL
FRONTOGENETIC FORCING WILL DIMINISH IN INTENSITY THIS MORNING AS
DRY AIR AND SUBSIDENCE CONTINUE TO SLOWLY WORK INTO THE REGION.
DRY AIR NEAR THE SURFACE HAS ALREADY PENETRATED AS FAR SOUTHEAST
AS AN ATHENS TO TEMPLE LINE...BUT IT IS THE MOISTURE ALOFT THAT WE
HAVE TO WORRY ABOUT EARLY THIS MORNING. EXPECT ALL LIGHT RAIN/RAIN
SHOWERS TO MOVE EAST AFTER 18Z. DID KEEP IN A 20 PERCENT CHANCE
FOR A RAIN/SLEET MIX FOR LOCATIONS ALONG AND NORTH OF A
GAINESVILLE TO MCKINNEY TO COOPER LINE AFTER SUNRISE JUST IN CASE
THE H800 FRONTOGENESIS SCENARIO DESCRIBED ABOVE PANS OUT. THESE
LOCATIONS WOULD ALSO HAVE TO BE INCLUDED IN A BRIEF FREEZING RAIN
ADVISORY IF THIS PRECIPITATION DOES MANAGE TO DEVELOP AROUND/JUST
BEFORE SUNRISE. IF IT DOES NOT...THESE AREAS WILL LIKELY REMAIN
DRY THIS MORNING.
WE SHOULD SEE SOME SUNSHINE BY LATE THIS AFTERNOON...HOWEVER NOT
MUCH OF A WARM-UP IS EXPECTED TODAY AS NORTH WINDS AND MORNING
CLOUD COVER HELP TO KEEP TEMPERATURES IN THE LOWER TO MID 40S FOR
HIGHS FOR MOST LOCATIONS. FOR TONIGHT...ANOTHER STRONG SHORTWAVE
TROUGH IS EXPECTED TO MOVE OVER THE SOUTH PLAINS. THIS TROUGH WAS
OVER THE SOUTHERN CA COAST PER EARLY MORNING WATER VAPOR IMAGERY.
THIS TROUGH HAS A WELL-DEFINED CYCLONIC CIRCULATION IN WATER VAPOR
IMAGERY AND IS PROGGED TO SEND STRONG LARGE SCALE FORCING FOR
ASCENT OVER THE REGION AS IT MOVES NORTHEAST TONIGHT AND INTO
MONDAY MORNING.
FOR MOST OF NORTH TX...THIS STRONG FORCING FOR ASCENT IS EXPECTED
TO GO UNNOTICED AS DRY AIR AND SUBSIDENCE ARE EXPECTED TO HAVE
LEFT THE ATMOSPHERE RELATIVELY STABLE BY LATE TONIGHT.
HOWEVER...THE GFS/NAM/ECMWF ALL SHOW RELATIVELY STRONG AND
PERSISTENT ISENTROPIC LIFT ON THE 305 K SURFACE IN BETWEEN 06 AND
12Z MONDAY MORNING OVER THE FAR SOUTHEASTERN COUNTIES OF THE CWA.
MODELS DO NOT SHOW MUCH IN THE WAY OF QPF...HOWEVER MID-LEVEL
MOISTURE WILL LIKELY RESIDE NEAR THE GULF COAST BEFORE THIS TROUGH
MOVES OVER THE REGION TONIGHT. IT SEEMS REASONABLE THAT SOME OF
THIS MOISTURE WILL RETURN ON THE 305K SURFACE (NEAR THE H700 LEVEL
TONIGHT) AND RESULT IN SOME PERSISTENT MID-LEVEL PRECIPITATION
PRODUCTION BEFORE SUNRISE MONDAY.
THE LOWER TROPOSPHERE IS EXPECTED TO BE QUITE DRY BEFORE THIS
PROCESS STARTS...SO A SIGNIFICANT AMOUNT OF THIS MID-LEVEL
PRECIPITATION IS LIKELY TO EVAPORATE BEFORE REACHING THE GROUND.
REGARDLESS...CONFIDENCE IN THE MID-LEVEL PRECIPITATION PRODUCTION
IS HIGH...SO WENT AHEAD AND MENTIONED A 20 PERCENT CHANCE OF RAIN
OR FREEZING RAIN SOUTHEAST OF AN ATHENS TO TEMPLE LINE (NOT
INCLUDING WACO AT THIS TIME) FOR EARLY MONDAY MORNING. DO NOT
THINK THE IMPACTS OF THIS WILL BE HIGH UNLESS THE LOWER ATMOSPHERE
SATURATES QUICKER THAN EXPECTED. LIGHT PRECIPITATION WILL LIKELY
CONTINUE AFTER SUNRISE MONDAY MORNING FOR THESE
LOCATIONS...HOWEVER TEMPERATURES ARE LIKELY TO WARM ABOVE FREEZING
AFTER SUNRISE. WE MAY HAVE TO CONSIDER A WINTER WEATHER OR
FREEZING RAIN ADVISORY IF IT LOOKS LIKE MORE PRECIPITATION WILL
MAKE IT TO THE GROUND...BUT CONFIDENCE IS TOO LOW TO GO WITH
ANYTHING AT THIS TIME.
FOR MID-WEEK...THE ECMWF HAS COME MORE IN LINE WITH THE NAEFS
SOLUTION INDICATING THAT THE LONGWAVE TROUGH OVER THE WESTERN
THIRD OF THE CONUS WILL CONSOLIDATE AND MOVE EAST AS A POSITIVELY
TILTED TROUGH TUESDAY NIGHT INTO WEDNESDAY. THIS SOLUTION LIMITS
LARGE SCALE FORCING FOR ASCENT OVER NORTH AND CENTRAL TX BY
KEEPING LOW LEVEL FLOW VEERED AS IT MOVES OVER THE AREA. THIS
WOULD ALSO PREVENT ANY SIGNIFICANT MOISTURE FROM RETURNING TO THE
REGION OUT AHEAD OF THIS UPPER TROUGH. THE 00 AND 06Z NAM
SOLUTIONS BOTH PREFER THE STRONG AND SLOW MOVING CUT-OFF LOW
SOLUTION ADVERTISED BY THE ECMWF THE PAST FEW DAYS. WHILE THIS
SOLUTION IS AN OUTLIER SOLUTION...WE WILL CONTINUE TO WATCH FOR
ANY SIGN THAT THIS SOLUTION COULD VERIFY AS IT WOULD LIKELY ALLOW
FOR A SIGNIFICANT ICE STORM IN THE REGION IF IT VERIFIED. THIS
FORECAST CONTINUES TO SIDE WITH THE CONSENSUS OF THE NAEFS AND THE
13/00Z ECMWF AS THIS IS BY FAR THE MOST LIKELY OUTCOME. HOWEVER
WILL NOT COMPLETELY IGNORE THE NAM AS IT WOULD BRING A HIGH IMPACT
WINTER WEATHER EVENT TO SOME PART OF NORTH OR CENTRAL TX.
EXTENDED...ONCE THE LONGER WAVE TROUGH MOVES OUT OF THE
REGION...WE SHOULD SEE A SLOW WARMING TREND FOR THE REGION AS A
BLOCKING RIDGE SETS UP OVER THE WESTERN CONUS COAST KEEPING MORE
OR LESS NORTHWEST AND CONFLUENT FLOW OVER THE SOUTH PLAINS. THIS
WARM UP COULD COME TO AN ABRUPT END EARLY NEXT WEEK AS BOTH THE
GFS AND THE ECMWF HAVE A STRONG COLD FRONT MOVING SOUTH THROUGH
THE GREAT PLAINS. THE GFS COOLS US DOWN...BUT ALLOWS THE COLD AIR
TO MODIFY TO THE POINT THAT IT BEHAVES LIKE A TYPICAL WINTER COLD
FRONT FOR TEXAS. THAT IS WE COOL DOWN SIGNIFICANTLY...BUT
OVERNIGHT LOWS TEND TO SAY IN THE MID TO UPPER 20S WHILE HIGHS
CLIMB ABOVE FREEZING.
THE ECMWF BRINGS A SIGNIFICANT ARCTIC OUTBREAK SOUTH THROUGH THE
PLAINS...WHICH WOULD IMPACT NORTH TX SUNDAY NIGHT OR MONDAY IF IT
VERIFIED. THE 13/00Z ECMWF HAS A 1053 MB (MSLP) SURFACE HIGH
BARRELING SOUTH INTO THE CENTRAL PLAINS BEHIND THIS FRONT...WHICH
IS A SIGN OF A VERY COLD ARCTIC AIR INVASION OF THE PLAINS. THIS
IS NOT THE MOST LIKELY SOLUTION TO VERIFY AT THIS TIME...BUT IT
BEARS WATCHING AS WE GET CLOSER TO NEXT WEEKEND AND EARLY NEXT
WEEK. THE ECMWF WOULD BRING LOWS DOWN INTO THE TEENS IF NOT LOWER
ACROSS NORTH TX WHICH COULD CERTAINLY HAVE A BIG IMPACT ON THE
REGION. THIS IS SLIGHTLY BEYOND THE OFFICIAL FORECAST PERIOD AT
THIS TIME...SO WILL WATCH FOR MORE CONSISTENCY AMONGST MODELS
BEFORE JUMPING ON AN ARCTIC OUTBREAK TO START OFF THE NEXT WORK
WEEK.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 42 26 44 28 45 / 10 10 5 10 10
WACO, TX 45 27 43 27 45 / 10 10 10 10 10
PARIS, TX 41 25 44 26 43 / 20 10 10 10 10
DENTON, TX 42 24 43 23 45 / 10 10 5 10 10
MCKINNEY, TX 42 24 44 24 43 / 20 10 10 10 10
DALLAS, TX 42 27 44 29 44 / 10 10 10 10 10
TERRELL, TX 44 26 43 27 43 / 10 10 10 10 10
CORSICANA, TX 44 28 44 30 43 / 10 10 10 10 10
TEMPLE, TX 46 27 43 27 44 / 10 10 10 10 10
MINERAL WELLS, TX 42 22 43 22 44 / 5 10 5 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
425 AM CST SUN JAN 13 2013
.DISCUSSION...
SHORT TERM WINTER WEATHER/FORECAST CONCERNS...
DID NOT MAKE ANY SIGNIFICANT CHANGES TO THE FORECAST FROM THE 139
AM CST FORECAST UPDATE/AFD. THERE IS STILL NO MODEL GUIDANCE THAT
HAS A GOOD HANDLE ON WINTRY PRECIPITATION FALLING NORTHWEST OF THE
METROPLEX EARLY THIS MORNING. THE HRRR IS CLOSEST...BUT DOESNT
SEEM TO KNOW WHAT IS CAUSING THE WINTRY PRECIPITATION. THE HRRR
CONSISTENTLY INITIALIZES THE RADAR RETURNS AND THEN ALLOWS THEM TO
DISSIPATE SHORTLY THEREAFTER WHICH IS A GOOD SIGN THAT THE MODEL
IS NOT RESOLVING THE FORCING MECHANISM THAT IS RESPONSIBLE FOR THE
PRESENCE OF THE PRECIPITATION. AT ANY RATE...DRAWING BACK ON
MORNING UPDATE DISCUSSIONS...THE GFS FORECAST THAT H700 CONFLUENCE
WOULD DISSIPATE EARLY THIS MORNING SEEMS TO BE SPOT ON ACCORDING
TO REGIONAL VWP OUTPUT. THE BEST H700 CONFLUENCE HAD MOVED NORTH
OF THE RED RIVER AS OF 09Z...AND LIGHT WINTRY PRECIPITATION WAS
LIFTING NORTHEAST AS WELL. THERE IS STILL SOME CONCERN FOR H800
FRONTOGENETIC FORCING ALONG A SHERMAN TO FORT WORTH TO GRANBURY
LINE AROUND SUNRISE RESULTING IN SOME SHALLOW CONVECTION
INITIATION. THE GFS CONTINUES TO ADVERTISE THIS FORCING FOR
ASCENT NEAR THE H800 LEVEL WITH A 100 MB LAYER ABOVE IT
CHARACTERIZED BY DECREASING THETA-E TEMPERATURES WITH
HEIGHT (ESSENTIALLY POSITIVE CAPE).
THAT SAID...THERE IS NO OBSERVATIONAL EVIDENCE THAT STRONG LIFT IS
OCCURRING AT THIS TIME AS THERE ARE NO RAPIDLY COOLING CLOUD TOPS
OR LIGHT MID-LEVEL RADAR REFLECTIVITY RETURNS OVER THESE AREAS AT
THE TIME OF THIS DISCUSSION. THEREFORE WILL NOT BE ISSUING A
FREEZING RAIN ADVISORY FROM SHERMAN...THROUGH THE DFW METROPLEX
AND SOUTHWEST TOWARDS GRANBURY AT THIS TIME. OF COURSE WE WILL
CONTINUE TO MONITOR THIS SITUATION CLOSELY THROUGH SUNRISE AS ANY
DEVELOPING PRECIPITATION WILL LIKELY BE COMPOSED OF SUPERCOOLED
WATER. WHILE THIS WOULD FALL IN LIQUID FORM...IT WOULD FREEZE
IMMEDIATELY UPON CONTACT WITH ANY SURFACE THAT IS ALSO AT OR BELOW
FREEZING. AT THIS TIME IT LOOKS AS THOUGH MOST PRECIPITATION
DEVELOPMENT WILL REMAIN SOUTHEAST OF THIS LINE THROUGH
SUNRISE...DIMINISHING THE THREAT FOR FREEZING RAIN OR SLEET.
TODAY THROUGH MONDAY...ALL GUIDANCE INDICATES THAT LOW-LEVEL
FRONTOGENETIC FORCING WILL DIMINISH IN INTENSITY THIS MORNING AS
DRY AIR AND SUBSIDENCE CONTINUE TO SLOWLY WORK INTO THE REGION.
DRY AIR NEAR THE SURFACE HAS ALREADY PENETRATED AS FAR SOUTHEAST
AS AN ATHENS TO TEMPLE LINE...BUT IT IS THE MOISTURE ALOFT THAT WE
HAVE TO WORRY ABOUT EARLY THIS MORNING. EXPECT ALL LIGHT RAIN/RAIN
SHOWERS TO MOVE EAST AFTER 18Z. DID KEEP IN A 20 PERCENT CHANCE
FOR A RAIN/SLEET MIX FOR LOCATIONS ALONG AND NORTH OF A
GAINESVILLE TO MCKINNEY TO COOPER LINE AFTER SUNRISE JUST IN CASE
THE H800 FRONTOGENESIS SCENARIO DESCRIBED ABOVE PANS OUT. THESE
LOCATIONS WOULD ALSO HAVE TO BE INCLUDED IN A BRIEF FREEZING RAIN
ADVISORY IF THIS PRECIPITATION DOES MANAGE TO DEVELOP AROUND/JUST
BEFORE SUNRISE. IF IT DOES NOT...THESE AREAS WILL LIKELY REMAIN
DRY THIS MORNING.
WE SHOULD SEE SOME SUNSHINE BY LATE THIS AFTERNOON...HOWEVER NOT
MUCH OF A WARM-UP IS EXPECTED TODAY AS NORTH WINDS AND MORNING
CLOUD COVER HELP TO KEEP TEMPERATURES IN THE LOWER TO MID 40S FOR
HIGHS FOR MOST LOCATIONS. FOR TONIGHT...ANOTHER STRONG SHORTWAVE
TROUGH IS EXPECTED TO MOVE OVER THE SOUTH PLAINS. THIS TROUGH WAS
OVER THE SOUTHERN CA COAST PER EARLY MORNING WATER VAPOR IMAGERY.
THIS TROUGH HAS A WELL-DEFINED CYCLONIC CIRCULATION IN WATER VAPOR
IMAGERY AND IS PROGGED TO SEND STRONG LARGE SCALE FORCING FOR
ASCENT OVER THE REGION AS IT MOVES NORTHEAST TONIGHT AND INTO
MONDAY MORNING.
FOR MOST OF NORTH TX...THIS STRONG FORCING FOR ASCENT IS EXPECTED
TO GO UNNOTICED AS DRY AIR AND SUBSIDENCE ARE EXPECTED TO HAVE
LEFT THE ATMOSPHERE RELATIVELY STABLE BY LATE TONIGHT.
HOWEVER...THE GFS/NAM/ECMWF ALL SHOW RELATIVELY STRONG AND
PERSISTENT ISENTROPIC LIFT ON THE 305 K SURFACE IN BETWEEN 06 AND
12Z MONDAY MORNING OVER THE FAR SOUTHEASTERN COUNTIES OF THE CWA.
MODELS DO NOT SHOW MUCH IN THE WAY OF QPF...HOWEVER MID-LEVEL
MOISTURE WILL LIKELY RESIDE NEAR THE GULF COAST BEFORE THIS TROUGH
MOVES OVER THE REGION TONIGHT. IT SEEMS REASONABLE THAT SOME OF
THIS MOISTURE WILL RETURN ON THE 305K SURFACE (NEAR THE H700 LEVEL
TONIGHT) AND RESULT IN SOME PERSISTENT MID-LEVEL PRECIPITATION
PRODUCTION BEFORE SUNRISE MONDAY.
THE LOWER TROPOSPHERE IS EXPECTED TO BE QUITE DRY BEFORE THIS
PROCESS STARTS...SO A SIGNIFICANT AMOUNT OF THIS MID-LEVEL
PRECIPITATION IS LIKELY TO EVAPORATE BEFORE REACHING THE GROUND.
REGARDLESS...CONFIDENCE IN THE MID-LEVEL PRECIPITATION PRODUCTION
IS HIGH...SO WENT AHEAD AND MENTIONED A 20 PERCENT CHANCE OF RAIN
OR FREEZING RAIN SOUTHEAST OF AN ATHENS TO TEMPLE LINE (NOT
INCLUDING WACO AT THIS TIME) FOR EARLY MONDAY MORNING. DO NOT
THINK THE IMPACTS OF THIS WILL BE HIGH UNLESS THE LOWER ATMOSPHERE
SATURATES QUICKER THAN EXPECTED. LIGHT PRECIPITATION WILL LIKELY
CONTINUE AFTER SUNRISE MONDAY MORNING FOR THESE
LOCATIONS...HOWEVER TEMPERATURES ARE LIKELY TO WARM ABOVE FREEZING
AFTER SUNRISE. WE MAY HAVE TO CONSIDER A WINTER WEATHER OR
FREEZING RAIN ADVISORY IF IT LOOKS LIKE MORE PRECIPITATION WILL
MAKE IT TO THE GROUND...BUT CONFIDENCE IS TOO LOW TO GO WITH
ANYTHING AT THIS TIME.
FOR MID-WEEK...THE ECMWF HAS COME MORE IN LINE WITH THE NAEFS
SOLUTION INDICATING THAT THE LONGWAVE TROUGH OVER THE WESTERN
THIRD OF THE CONUS WILL CONSOLIDATE AND MOVE EAST AS A POSITIVELY
TILTED TROUGH TUESDAY NIGHT INTO WEDNESDAY. THIS SOLUTION LIMITS
LARGE SCALE FORCING FOR ASCENT OVER NORTH AND CENTRAL TX BY
KEEPING LOW LEVEL FLOW VEERED AS IT MOVES OVER THE AREA. THIS
WOULD ALSO PREVENT ANY SIGNIFICANT MOISTURE FROM RETURNING TO THE
REGION OUT AHEAD OF THIS UPPER TROUGH. THE 00 AND 06Z NAM
SOLUTIONS BOTH PREFER THE STRONG AND SLOW MOVING CUT-OFF LOW
SOLUTION ADVERTISED BY THE ECMWF THE PAST FEW DAYS. WHILE THIS
SOLUTION IS AN OUTLIER SOLUTION...WE WILL CONTINUE TO WATCH FOR
ANY SIGN THAT THIS SOLUTION COULD VERIFY AS IT WOULD LIKELY ALLOW
FOR A SIGNIFICANT ICE STORM IN THE REGION IF IT VERIFIED. THIS
FORECAST CONTINUES TO SIDE WITH THE CONSENSUS OF THE NAEFS AND THE
13/00Z ECMWF AS THIS IS BY FAR THE MOST LIKELY OUTCOME. HOWEVER
WILL NOT COMPLETELY IGNORE THE NAM AS IT WOULD BRING A HIGH IMPACT
WINTER WEATHER EVENT TO SOME PART OF NORTH OR CENTRAL TX.
EXTENDED...ONCE THE LONGER WAVE TROUGH MOVES OUT OF THE
REGION...WE SHOULD SEE A SLOW WARMING TREND FOR THE REGION AS A
BLOCKING RIDGE SETS UP OVER THE WESTERN CONUS COAST KEEPING MORE
OR LESS NORTHWEST AND CONFLUENT FLOW OVER THE SOUTH PLAINS. THIS
WARM UP COULD COME TO AN ABRUPT END EARLY NEXT WEEK AS BOTH THE
GFS AND THE ECMWF HAVE A STRONG COLD FRONT MOVING SOUTH THROUGH
THE GREAT PLAINS. THE GFS COOLS US DOWN...BUT ALLOWS THE COLD AIR
TO MODIFY TO THE POINT THAT IT BEHAVES LIKE A TYPICAL WINTER COLD
FRONT FOR TEXAS. THAT IS WE COOL DOWN SIGNIFICANTLY...BUT
OVERNIGHT LOWS TEND TO SAY IN THE MID TO UPPER 20S WHILE HIGHS
CLIMB ABOVE FREEZING.
THE ECMWF BRINGS A SIGNIFICANT ARCTIC OUTBREAK SOUTH THROUGH THE
PLAINS...WHICH WOULD IMPACT NORTH TX SUNDAY NIGHT OR MONDAY IF IT
VERIFIED. THE 13/00Z ECMWF HAS A 1053 MB (MSLP) SURFACE HIGH
BARRELING SOUTH INTO THE CENTRAL PLAINS BEHIND THIS FRONT...WHICH
IS A SIGN OF A VERY COLD ARCTIC AIR INVASION OF THE PLAINS. THIS
IS NOT THE MOST LIKELY SOLUTION TO VERIFY AT THIS TIME...BUT IT
BEARS WATCHING AS WE GET CLOSER TO NEXT WEEKEND AND EARLY NEXT
WEEK. THE ECMWF WOULD BRING LOWS DOWN INTO THE TEENS IF NOT LOWER
ACROSS NORTH TX WHICH COULD CERTAINLY HAVE A BIG IMPACT ON THE
REGION. THIS IS SLIGHTLY BEYOND THE OFFICIAL FORECAST PERIOD AT
THIS TIME...SO WILL WATCH FOR MORE CONSISTENCY AMONGST MODELS
BEFORE JUMPING ON AN ARCTIC OUTBREAK TO START OFF THE NEXT WORK
WEEK.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 42 26 44 28 45 / 10 10 5 10 10
WACO, TX 45 27 43 27 45 / 10 10 10 10 10
PARIS, TX 41 25 44 26 43 / 20 10 10 10 10
DENTON, TX 42 24 43 23 45 / 10 10 5 10 10
MCKINNEY, TX 42 24 44 24 43 / 20 10 10 10 10
DALLAS, TX 42 27 44 29 44 / 10 10 10 10 10
TERRELL, TX 44 26 43 27 43 / 10 10 10 10 10
CORSICANA, TX 44 28 44 30 43 / 10 10 10 10 10
TEMPLE, TX 46 27 43 27 44 / 10 10 10 10 10
MINERAL WELLS, TX 42 22 43 22 44 / 5 10 5 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
739 AM CST SUN JAN 13 2013
.SHORT TERM...
739 AM CST SUN JAN 13 2013
BANDS OF FLURRIES AND LIGHT SNOW HAS DEVELOPED AHEAD OF A TROUGH
OVER CENTRAL WISCONSIN. THE RAP IS HANDLING THE MOISTURE
ASSOCIATED WITH THIS TROUGH THE BEST...SO TRENDED THE FORECAST
TOWARD IT. LITTLE...IF ANY...ACCUMULATION IS EXPECTED THIS MORNING.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
212 AM CST SUN JAN 13 2013
NORTHWEST FLOW ALOFT IS EXPECTED TO BE OVER THE UPPER MIDWEST
THROUGH THE PERIOD AS THE POLAR VORTEX SHIFTS SOUTH ACROSS HUDSON
BAY AND THEN TOWARD THE ATLANTIC. A COUPLE OF SHORT WAVE TROUGHS
SHOULD PASS OVER THE REGION IN THIS NORTHWEST FLOW. MODELS HAVE
NOW SETTLED IN ON THE TIMING OF THE FIRST WAVE COMING ACROSS
TUESDAY NIGHT AND WEDNESDAY. THIS WILL CAUSE A SURFACE LOW TO MOVE
ACROSS SOUTHERN CANADA WITH A COLD FRONT PASSING THROUGH WEDNESDAY.
THE 13.00Z ECMWF SUGGESTS THE POTENTIAL FOR SOME LIGHT SNOW TO
LINGER INTO WEDNESDAY NIGHT BUT THIS MAY END UP BEING SOME LAKE
EFFECT SNOW OFF OF LAKE SUPERIOR THAT STAYS NORTH OF THE AREA.
PLAN TO CARRY SOME LIGHT SNOW CHANCES FOR TUESDAY NIGHT AND
WEDNESDAY. THE NEXT SHORT WAVE TROUGH AND SURFACE LOW IS PRESENTLY
EXPECTED TO COME ACROSS THURSDAY NIGHT BUT SOME QUESTION AS
WHETHER THIS SYSTEM WILL BE ABLE TO PRODUCE ANY LIGHT SNOW WITH
SATURATION A CONCERN. AFTER THAT...ANOTHER WAVE WILL COME THROUGH
SATURDAY BUT DIFFERENCES ON THE TRACK OF THE SURFACE LOW WITH THE
GFS SOUTH OF THE AREA AND THE ECMWF WELL TO THE NORTH. WILL STAY
WITH THE MODEL CONSENSUS GRIDS AND SHOW A CHANCE OF LIGHT SNOW
ACROSS THE NORTH.
&&
.AVIATION...TODAY AND TONIGHT
620 AM CST SUN JAN 13 2013
A TROUGH NORTH OF INTERSTATE 94 IS BRINGING AREAS OF MVFR CLOUDS
INTO THE TAF SITES. OVERALL THE RAP IS HANDLING THESE CLOUDS THE
BEST SO TRENDED THE FORECAST TOWARD IT. KLSE WILL SEE A BROKEN
DECK OF MVFR CLOUDS THROUGH 13.21Z. KRST LOOKS LIKE THEY WILL BE
ON THE WESTERN PERIPHERY OF THESE CLOUDS...SO JUST PUT A TEMPO
GROUP OF BROKEN MVFR CLOUDS THROUGH 13.19Z. SUBSIDENCE IN THE WAKE
OF TROUGH WILL RESULT IN SCATTERED DECK OF 3000 FOOT CLOUDS FROM
LATE THIS AFTERNOON THROUGH TONIGHT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
212 AM CST SUN JAN 13 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...04
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
621 AM CST SUN JAN 13 2013
.SHORT TERM...THROUGH TUESDAY
212 AM CST SUN JAN 13 2013
SURFACE ANALYSIS THIS MORNING SHOWS AN AREA OF LOW PRESSURE OVER
CENTRAL INDIANA AND HIGH PRESSURE OVER SOUTH DAKOTA.
REGIONAL RADARS THIS MORNING SHOWING SOME LIGHT SNOW FALLING ON
THE NORTHWEST SIDE OF THE INDIANA SURFACE LOW. THIS SNOW IS
FALLING OVER EXTREME EASTERN IOWA INTO NORTHERN ILLINOIS AND
SOUTHEAST WISCONSIN. DESPITE THE LOCAL RADAR SHOWING SOME ECHOES
OVER PARTS OF ADAMS...RICHLAND AND GRANT COUNTIES NOTHING IS
HITTING THE GROUND AS THERE IS JUST TOO MUCH LOW LEVEL DRY AIR IN
PLACE WITH TEMP/DEW POINT SPREADS OF 7 TO 10 DEGREES. EVEN DRIER
AIR IS JUST OFF TO THE WEST SO NOT ANTICIPATING ANY SNOW REACHING
THE GROUND IN THE FORECAST AREA...ESPECIALLY AS THE SURFACE LOW
CONTINUES TO PULL AWAY FROM THE AREA. SOME FLURRIES MAY FALL TODAY
OVER THE NORTHERN SECTIONS OF THE FORECAST AREA AS A TROUGH OF LOW
PRESSURE IS EXPECTED TO EXTEND FROM THE SURFACE LOW AS IT GETS
INTO NORTHERN LOWER MICHIGAN BACK ACROSS NORTHERN WISCONSIN INTO
MINNESOTA. A BAND OF LOWER CONDENSATION PRESSURE DEFICITS ON THE
270K SURFACE WILL RESIDE NEAR THE TROUGH. THE 13.00Z NAM BUFKIT
SOUNDINGS SHOW LITTLE TO NO VERTICAL MOTION ALONG THE TROUGH WHILE
THE 13.00Z GFS DOES HINT AT SOME WEAK LIFT. EVEN IF THE GFS IS
CORRECT...THE VERTICAL MOTION IS NOT ENOUGH TO PRODUCE MORE THAN
FLURRIES.
THE AREA OF HIGH PRESSURE WILL EXPAND OVER THE UPPER MIDWEST
TONIGHT...REMAINING THROUGH MONDAY NIGHT BEFORE SLIPPING OFF TO
THE SOUTHEAST TUESDAY. AN AREA OF LOW PRESSURE WILL MOVING
SOUTHEAST ACROSS MANITOBA AND SASKATCHEWAN TUESDAY AND THE FLOW
WILL TURN TO THE SOUTHWEST BETWEEN THE LOW AND DEPARTING HIGH.
WITH WARMER AIR COMING IN ON THE SOUTHWEST FLOW...TEMPERATURES ARE
EXPECTED TO WARM INTO THE MIDDLE 20S TO LOWER 30S. WITH THE LACK
OF SNOW COVER...THERE IS THE POTENTIAL THAT THESE COULD GO EVEN
HIGHER WITH THE 12.12Z ECMWF BEING ABOUT A CATEGORY WARMER.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
212 AM CST SUN JAN 13 2013
NORTHWEST FLOW ALOFT IS EXPECTED TO BE OVER THE UPPER MIDWEST
THROUGH THE PERIOD AS THE POLAR VORTEX SHIFTS SOUTH ACROSS HUDSON
BAY AND THEN TOWARD THE ATLANTIC. A COUPLE OF SHORT WAVE TROUGHS
SHOULD PASS OVER THE REGION IN THIS NORTHWEST FLOW. MODELS HAVE
NOW SETTLED IN ON THE TIMING OF THE FIRST WAVE COMING ACROSS
TUESDAY NIGHT AND WEDNESDAY. THIS WILL CAUSE A SURFACE LOW TO MOVE
ACROSS SOUTHERN CANADA WITH A COLD FRONT PASSING THROUGH WEDNESDAY.
THE 13.00Z ECMWF SUGGESTS THE POTENTIAL FOR SOME LIGHT SNOW TO
LINGER INTO WEDNESDAY NIGHT BUT THIS MAY END UP BEING SOME LAKE
EFFECT SNOW OFF OF LAKE SUPERIOR THAT STAYS NORTH OF THE AREA.
PLAN TO CARRY SOME LIGHT SNOW CHANCES FOR TUESDAY NIGHT AND
WEDNESDAY. THE NEXT SHORT WAVE TROUGH AND SURFACE LOW IS PRESENTLY
EXPECTED TO COME ACROSS THURSDAY NIGHT BUT SOME QUESTION AS
WHETHER THIS SYSTEM WILL BE ABLE TO PRODUCE ANY LIGHT SNOW WITH
SATURATION A CONCERN. AFTER THAT...ANOTHER WAVE WILL COME THROUGH
SATURDAY BUT DIFFERENCES ON THE TRACK OF THE SURFACE LOW WITH THE
GFS SOUTH OF THE AREA AND THE ECMWF WELL TO THE NORTH. WILL STAY
WITH THE MODEL CONSENSUS GRIDS AND SHOW A CHANCE OF LIGHT SNOW
ACROSS THE NORTH.
&&
.AVIATION...TODAY AND TONIGHT
620 AM CST SUN JAN 13 2013
A TROUGH NORTH OF INTERSTATE 94 IS BRINGING AREAS OF MVFR CLOUDS
INTO THE TAF SITES. OVERALL THE RAP IS HANDLING THESE CLOUDS THE
BEST SO TRENDED THE FORECAST TOWARD IT. KLSE WILL SEE A BROKEN
DECK OF MVFR CLOUDS THROUGH 13.21Z. KRST LOOKS LIKE THEY WILL BE
ON THE WESTERN PERIPHERY OF THESE CLOUDS...SO JUST PUT A TEMPO
GROUP OF BROKEN MVFR CLOUDS THROUGH 13.19Z. SUBSIDENCE IN THE WAKE
OF TROUGH WILL RESULT IN SCATTERED DECK OF 3000 FOOT CLOUDS FROM
LATE THIS AFTERNOON THROUGH TONIGHT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
212 AM CST SUN JAN 13 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
145 PM EST SUN JAN 13 2013
.SHORT TERM (THIS EVENING THROUGH TUESDAY NIGHT)...
18Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A HIGHLY AMPLIFIED UPPER
LEVEL PATTERN REMAINS IN PLACE OVER THE CONUS. PATTERN CONSISTS OF A
LARGE AND IMPRESSIVE LONGWAVE TROUGH OVER THE WESTERN 2/3RDS OF THE
CONUS FOLLOWED DOWNSTREAM BY LONGWAVE RIDGING EXTENDING FROM THE
EASTERN GULF OF MEXICO NORTHWARD ALONG THE ATLANTIC SEABOARD. THE
DOMINANT WESTERN TROUGH IS BEGINNING TO WIN THE OVERALL BATTLE AND
WE WILL SEE THE NORTHERN PORTION OF THE EASTERN RIDGE QUICKLY BREAK
DOWN OVER THE NEXT 24 HOURS. LUCKILY FOR THOSE WITH OUTDOOR
PLANS...GLOBAL GUIDANCE IS IN GOOD AGREEMENT THAT THE RIDGE WILL
HOLD STRONG THROUGH TUESDAY OVER OUR HEADS...KEEPING OUR LOCAL
WEATHER CONTINUED GENERALLY DRY AND UNSEASONABLY WARM.
AT THE SURFACE...HIGH PRESSURE CENTERED OFF THE NORTHEAST FLORIDA
COAST CONTINUES TO RIDGE BACK TO THE WEST ACROSS NORTHERN PORTIONS
OF THE STATE. THIS RIDGE AXIS IS EXPECTED TO SETTLE A BIT FURTHER
SOUTH THE NEXT DAY OR 2. THE WEAKER GRADIENT AND CONTINUED STRONG
SURFACE HEATING WILL LEAD TO BETTER CHANCES FOR FEEBLE AFTERNOON
SEA-BREEZES NEAR THE COAST...ESPECIALLY ALONG THE NATURE COAST WHERE
THE LAND/SEA TEMP GRADIENT REMAINS THE GREATEST. MAY BE A BIT COOLER
THE NEXT FEW AFTERNOON ALONG THE IMMEDIATE COAST OF THE NATURE COAST
DO TO THIS ONSHORE FLOW.
12Z KTBW SOUNDING PROFILE CONTINUED TO SHOW THE INFLUENCE OF THE
UPPER RIDGE WITH A SUBSIDENCE INVERSION AROUND 850MB...AND A DRY
COLUMN ABOVE. MOISTURE LEVELS INCREASE NEAR THE TOP OF THE COLUMN IN
THE FORM OF SOME "WISPY" CIRRUS TRYING TO OVERSPREAD FROM THE WEST.
SO FAR...MUCH OF THIS CIRRUS HAS BEEN EVAPORATING AS IT APPROACHES
THE SUPPRESSION OF THE RIDGE AXIS.
&&
.LONG TERM (TUESDAY NIGHT THROUGH SATURDAY)...LARGE HIGH PRESSURE
DOME OVER THE BAHAMAS AND FL WILL FINALLY BE NUDGED EAST LATE IN THE
PERIOD AS A DETACHED TROUGH OVER TX IS REABSORBED WHILE IT MOVES
EAST AND WEAKENS. IT APPEARS THIS WILL FINALLY LET A WEAK FRONTAL
BOUNDARY TO MOVE INTO THE REGION BRINGING A SLT CHANCE OF SHOW SHRA
MAINLY ACROSS CEN AND NRN ZONES. ECMWF IS MUCH MORE MOIST THAN THE
GFS...BUT GIVEN UNCERTAINTY WILL STICK WITH JUST 20 POPS ATTM FOR
THU THROUGH SAT TIMEFRAME FOR NOW. TEMPS WILL CONTINUE WELL ABOVE
NORMAL...ALTHOUGH A SLIGHT DECREASE IN HIGHS WILL OCCUR GIVEN
INCREASING MOISTURE AND THEN THE FRONTAL BOUNDARY IN THE AREA WILL
OCCUR THROUGH THE PERIOD. WHAT HAPPENS BEYOND THE FORECAST PERIOD
IS MORE INTERESTING AS IT APPEARS A HIGHLY AMPLIFIED PATTERN WILL
DEVELOP WITH MORE OF AN ERN US TROUGH THIS GO AROUND. THIS MEANS A
RETURN TO WINTER MAY BE IN STORE BEYOND THE CURRENT FORECAST PERIOD.
&&
.AVIATION...
EXPECTING VFR CONDITIONS TO PREVAIL FOR THE NEXT 24 HOURS. SOME FOG
MAY BRING MVFR VISIBILITIES TO LAL AND PGD BETWEEN 08Z AND 14Z...
BUT THINK STRATOCUMULUS CLOUDS WILL LIMIT RADIATIONAL COOLING
NECESSARY FOR MORE WIDESPREAD FOG DEVELOPMENT.
&&
.MARINE...
HIGH PRESSURE CENTERED OFF THE SOUTHEAST COAST WILL CONTINUE TO
RIDGE BACK TO THE WEST ACROSS THE FLORIDA PENINSULA AND NORTHEAST
GULF OF MEXICO THROUGH TUESDAY. THIS RIDGE WILL WEAKEN AND SHIFT
EAST BY WEDNESDAY AS A WEAK COLD FRONT APPROACHES FROM THE NORTH.
THIS FRONT IS EXPECTED TO ARRIVE ACROSS THE EASTERN GULF OF MEXICO
DURING THURSDAY.
&&
.FIRE WEATHER...
HIGH PRESSURE REMAINS IN CONTROL OF THE FORECAST AREA THROUGH
TUESDAY WITH A STABLE...GENERALLY DRY...AND UNSEASONABLY WARM
AIRMASS. DESPITE THE ABOVE NORMAL DAYTIME TEMPERATURES...THERE WILL
BE ENOUGH LOW LEVEL MOISTURE TO PREVENT ANY WIDESPREAD AREAS OF
CRITICALLY LOW RELATIVE HUMIDITY. THE NEXT COLD FRONT IS NOT
ANTICIPATED TO ARRIVE UNTIL MID-WEEK AND PROVIDE ONLY A SLIGHT
CHANCE OF A FEW SHOWERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 64 79 63 78 / 10 0 10 10
FMY 62 80 63 81 / 0 0 10 10
GIF 59 81 59 81 / 0 0 10 10
SRQ 62 78 60 78 / 0 0 10 10
BKV 56 81 54 81 / 10 0 10 10
SPG 65 78 64 77 / 0 0 10 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SHORT TERM/MARINE/FIRE WX...MROCZKA
AVIATION...JILLSON
LONG TERM...GITTINGER
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
412 PM CST SUN JAN 13 2013
.DISCUSSION...
246 PM CST
MAIN FORECAST CONCERN IS WITH MIXED WINTRY PRECIP OCCURRING ACROSS
EASTERN PARTS OF THE FORECAST AREA THIS AFTERNOON. ATTENTION THEN
SHIFTS TO SEASONABLY COLD BUT DRY WEATHER FOR MUCH OF THIS WEEK.
SOME INDICATIONS REMAIN THAT IT MAY EVENTUALLY TURN MUCH COLDER JUST
BEYOND THE END OF THE EXTENDED PERIOD.
NEAR TERM...REMAINDER OF THIS AFTERNOON/EARLY EVENING.
AREA OF MIXED WINTER PRECIP HAS SPREAD ACROSS THE FAR EASTERN PARTS
OF THE WFO LOT CWA THIS AFTERNOON. MID-LEVEL SHORT WAVE RESPONSIBLE
FOR THIS MESS IS CLEARLY IDENTIFIABLE IN GOES WATER VAPOR IMAGERY...
AND EXTRAPOLATION OF THIS FEATURE AS WELL AS WESTERN/TRAILING EDGE
OF RADAR DETECTABLE PRECIP INDICATES THAT THE MIXED PRECIP SHOULD
WIND DOWN FAIRLY QUICKLY IN THE 22-24Z (4-6 PM) TIMEFRAME. PATCHY
FLURRIES AND LIGHT FREEZING DRIZZLE ACROSS NORTHEAST IL SHOULD ALSO
END QUICKLY BY EVENING WITH LOSS OF FORCING BY EVENING. WARM
MID-LEVEL THERMAL PROFILE NOTED IN ILX 12Z SOUNDING DID INDEED
RESULT IN SOME SLEET/FREEZING RAIN ACROSS EASTERN AREAS THIS
AFTERNOON...THOUGH PRECIP WAS GENERALLY TRANSITIONING OVER TO LIGHT
SNOW AT 2 PM CST WITH SOME MODERATE SNOW AT TIMES AS INDICATED BY
VISIBILITY DOWN TO 3/4SM IN A FEW SPOTS A LITTLE EARLIER. AFTERNOON
VIS SATELLITE IMAGERY INDICATES CLOUDS CLEARING FROM THE WEST ACROSS
WESTERN IL...AND THIS TREND SHOULD CONTINUE THROUGH THE EVENING AS
THE UPPER TROUGH OVER THE MIDWEST LIFTS NORTHEAST...AND COLD/DRY LOW
LEVEL ADVECTION PERSISTS FROM THE WEST. WHILE IT WILL BE CHILLY
TONIGHT...HAVE GONE ABOVE MOS MINS FOR OVERNIGHT LOWS...AS MODELS
HAVE INITIALIZED SNOW COVER WHICH DID NOT ACTUALLY MATERIALIZE FROM
SATURDAY NIGHT. (WRF-NAM FOR INSTANCE HAS A 2-3 INCH STRIPE
INITIALIZED FROM BUREAU COUNTY TO MCHENRY COUNTY IN NORTHERN IL).
MEDIUM RANGE...MONDAY THROUGH THURSDAY...
SURFACE HIGH PRESSURE SPREADS ACROSS THE AREA ON MONDAY AS UPPER
TROUGH CURRENTLY ACROSS THE MISSISSIPPI VALLEY LIFTS NORTHEAST AND
AWAY FROM THE REGION. SPLIT UPPER FLOW FOCUSES ANY SIGNIFICANT
SENSIBLE WEATHER OVER THE SOUTHWESTERN CONUS WHERE A CLOSED UPPER
LOW DEVELOPS TONIGHT/MONDAY...AND ACROSS THE PACIFIC NORTHWEST WHERE
A STRONG UPPER JET STREAK MOVES IN OFF THE NORTH PACIFIC. THIS JET
EVENTUALLY LEADS TO A DEEPENING AREA OF SURFACE LOW PRESSURE IN THE
LEE OF THE CANADIAN ROCKIES WHICH MOVES EAST ACROSS ONTARIO THROUGH
EARLY WEDNESDAY. SURFACE HIGH PRESSURE RIDGE ACROSS THE MIDWEST
MONDAY/TUESDAY IS THUS DISPLACED SOUTHWARD AS PRESSURE FALLS DEVELOP
ACROSS THE UPPER MIDWEST AND NORTHERN LAKES IN ASSOCIATION WITH THE
CANADIAN LOW. DRY AND SEASONABLY COOL/COLD WEATHER WILL BE THE RULE
EARLY IN THE WEEK...MODERATING BACK TO SLIGHTLY ABOVE NORMAL TEMPS
IN THE 30S BY MID-WEEK AS WEST/SOUTHWEST FLOW INCREASES NORTH OF THE
RETREATING SURFACE RIDGE AND SOUTH OF THE ONTARIO LOW PRESSURE
SYSTEM. SURFACE COLD FRONT THEN TRAILS THE CANADIAN LOW ACROSS THE
CWA WEDNESDAY NIGHT...RESULTING IN COLDER TEMPS CLOSER TO NORMAL
(UPPER 20S) FOR THURSDAY. FRONT DOES NOT MAKE MUCH OF A SOUTHWARD
PUSH HOWEVER AND REALLY ONLY PROVIDES A GLANCING BRUSH OF COLDER AIR
AS THE MID/UPPER LEVEL FLOW BECOMES MORE WESTERLY. VARIOUS GUIDANCE
MAINTAIN VERY DRY MOISTURE PROFILES ACROSS THE MIDWEST THROUGH
MID-WEEK...RESULTING IN LITTLE/NO QPF EVEN WITH THE FROPA LATE
WEDNESDAY. THEREFORE IT APPEARS CHICAGO/S STREAK OF DAYS WITHOUT A 1
INCH SNOWFALL WILL CONTINUE THROUGH MID-JANUARY AT LEAST.
LONGER RANGE...FRIDAY-SUNDAY...
GUIDANCE REMAIN IN PRETTY GOOD AGREEMENT IN MAINTAINING
WEST-NORTHWEST FLOW ALOFT FRIDAY...BEFORE GRADUALLY AMPLIFYING LARGE
SCALE UPPER TROUGH OVER THE EASTERN HALF OF NORTH AMERICA THROUGH
THE WORK OF A COUPLE DEEP SHORT WAVE TROUGHS THROUGH THE WEEKEND.
COLDER TREND IN TEMPS BEGINS SUNDAY...THE LAST DAY OF THIS FORECAST
PACKAGE...THOUGH MODEL TRENDS CONTINUE TO SUGGEST A PLUNGE OF TRUE
BITTER COLD ARCTIC AIR MONDAY/TUESDAY OF THE FOLLOWING WEEK.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* PERIODIC MVFR CIGS LIKELY INTO EARLY EVENING WITH A FEW FLURRIES
IZZI
//DISCUSSION...UPDATED 18Z...
AS RAP OUTPUT CONTINUES TO DO A DECENT JOB IN HANDLING LOCATION
OF REFLECTIVITY HAVE FOLLOWED LATEST AVAILABLE VERSION /16Z/ AS
BASIS OF AFTERNOON AND EARLY EVENING FORECAST.
A SHORT WAVE HAS LIFTED FROM OVER FAR NORTHEAST TX AND SOUTHWEST
OK TO NORTHEASTERN AR AND SOUTHEASTERN MO DURING THE MORNING...
AND IS PROGGED TO MOVE NORTHEAST TO NORTHERN IL BY 00Z. HEAVIEST
PRECIPITATION WAS WELL TO THE SE THROUGH SW OF THE REGION...
CLOSER TO THE LOWER LEVEL BAROCLINIC ZONE. FURTHER NORTH...RADAR
ECHOES CONTINUE TO ADVANCE FROM CENTRAL IL TO THE FAR SOUTH TIP
OF LAKE MI AND NORTHWEST AND WEST CENTRAL IN AS THE SHORT WAVE
APPROACHES.
LOOP OF THE RAP COMPOSITE REFLECTIVITY FORECASTS SHOWS THE
NORTHWESTERN EDGE OF THE PRECIPITATION SHIELD MAKING NO FURTHER
NORTHWARD PROGRESS THIS AFTERNOON AND JUST GLANCING MDW BEFORE
MOVING OFF TO THE EAST BY EVENING AS SOUTHWEST WINDS VEER TO
WEST-SOUTHWEST AND WESTERLY IN THE LAYER FROM 1.5 TO 2.5 KM AGL
AND ADVECTING IN COLDER AND DRIER AIR FOLLOWING AN 850 HPA TROUGH
AXIS. THIS WILL ALSO RESULT IN SUBSIDENCE IN THE LOWER LAYERS AND
ANTICIPATE LOSS OF THE MVFR CEILINGS BY EARLY TO MID EVENING.
AS THE 700 HPA TROUGH MOVES ACROSS THE LOCAL AREA LATE THIS
EVENING SKIES SHOULD BECOME SKC TO SCT AS SUBSIDENCE EXPANDS UP
IN TO THE UPPER LEVELS.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* MEDIUM CONFIDENCE IN CEILING TRENDS AND WIND TRENDS THIS EVENING.
* HIGH CONFIDENCE IN ALL OTHER ELEMENTS
IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
245 PM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LIKELY FOR TUESDAY AFTERNOON THROUGH WEDNESDAY.
THIS AFTERNOON...LOW PRESSURE LIES OVER SOUTHERN QUEBEC WITH A
COLD FRONT EXTENDING SOUTHWEST INTO THE LOWER MISSISSIPPI
VALLEY...WITH HIGH PRESSURE SPRAWLING OVER THE NORTHERN AND CENTRAL
PLAINS. OVERNIGHT TONIGHT...THE LOW WILL LIFT NORTHEAST THROUGH
SOUTHERN QUEBEC WHILE THE COLD FRONT PUSHES THROUGH THE UPPER OHIO
RIVER VALLEY TO THE MID ATLANTIC REGION. BY TUESDAY...THE HIGH
WILL SPREAD ACROSS THE MIDDLE MISSISSIPPI VALLEY...TOWARD THE OHIO
VALLEY. MEANWHILE ANOTHER LOW WILL DROP SOUTHEAST INTO
SASKATCHEWAN AND DEEPEN AS IT MOVES ACROSS THE NORTHERN GREAT
LAKES REGION. THE COMBINATION OF NEARLY STATIONARY HIGH PRESSURE
OVER THE OHIO VALLEY...THE LOW DEEPENING AS IT SWINGS THROUGH THE
UPPER GREAT LAKES AND SOUTH CENTRAL CANADA AND AN APPROACHING
FRONTAL TROUGH ASSOCIATED WITH THE LOW WILL LEAD TO SOUTHWESTERLY
GALES DEVELOPING OVER THE NORTHERN PORTIONS OF THE LAKE BY TUESDAY
AFTERNOON...AND SPREADING TO THE SOUTHERN PORTIONS OF THE LAKE
THROUGH THE EVENING. SOUTHWEST GALES...TO 45 KT WILL PERSIST OVER
THE LAKE UNTIL THE COLD FRONT SWEEPS ACROSS THE LAKE LATE
WEDNESDAY AFTERNOON HIGH PRESSURE BUILDING ACROSS THE PLAINS
ALLOWS THE PRESSURE GRADIENT OVER THE LAKE TO RELAX ENOUGH FOR
WINDS TO DROP BELOW GALE FORCE.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM MONDAY.
GALE WATCH...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ669-LMZ671-LMZ868-LMZ870-LMZ872...3 PM TUESDAY TO 3 PM
WEDNESDAY.
GALE WATCH...LMZ080-LMZ673-LMZ675-LMZ777-LMZ779-LMZ874-LMZ876-
LMZ878...9 PM TUESDAY TO 3 PM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
247 PM CST SUN JAN 13 2013
.DISCUSSION...
246 PM CST
MAIN FORECAST CONCERN IS WITH MIXED WINTRY PRECIP OCCURRING ACROSS
EASTERN PARTS OF THE FORECAST AREA THIS AFTERNOON. ATTENTION THEN
SHIFTS TO SEASONABLY COLD BUT DRY WEATHER FOR MUCH OF THIS WEEK.
SOME INDICATIONS REMAIN THAT IT MAY EVENTUALLY TURN MUCH COLDER JUST
BEYOND THE END OF THE EXTENDED PERIOD.
NEAR TERM...REMAINDER OF THIS AFTERNOON/EARLY EVENING.
AREA OF MIXED WINTER PRECIP HAS SPREAD ACROSS THE FAR EASTERN PARTS
OF THE WFO LOT CWA THIS AFTERNOON. MID-LEVEL SHORT WAVE RESPONSIBLE
FOR THIS MESS IS CLEARLY IDENTIFIABLE IN GOES WATER VAPOR IMAGERY...
AND EXTRAPOLATION OF THIS FEATURE AS WELL AS WESTERN/TRAILING EDGE
OF RADAR DETECTABLE PRECIP INDICATES THAT THE MIXED PRECIP SHOULD
WIND DOWN FAIRLY QUICKLY IN THE 22-24Z (4-6 PM) TIMEFRAME. PATCHY
FLURRIES AND LIGHT FREEZING DRIZZLE ACROSS NORTHEAST IL SHOULD ALSO
END QUICKLY BY EVENING WITH LOSS OF FORCING BY EVENING. WARM
MID-LEVEL THERMAL PROFILE NOTED IN ILX 12Z SOUNDING DID INDEED
RESULT IN SOME SLEET/FREEZING RAIN ACROSS EASTERN AREAS THIS
AFTERNOON...THOUGH PRECIP WAS GENERALLY TRANSITIONING OVER TO LIGHT
SNOW AT 2 PM CST WITH SOME MODERATE SNOW AT TIMES AS INDICATED BY
VISIBILITY DOWN TO 3/4SM IN A FEW SPOTS A LITTLE EARLIER. AFTERNOON
VIS SATELLITE IMAGERY INDICATES CLOUDS CLEARING FROM THE WEST ACROSS
WESTERN IL...AND THIS TREND SHOULD CONTINUE THROUGH THE EVENING AS
THE UPPER TROUGH OVER THE MIDWEST LIFTS NORTHEAST...AND COLD/DRY LOW
LEVEL ADVECTION PERSISTS FROM THE WEST. WHILE IT WILL BE CHILLY
TONIGHT...HAVE GONE ABOVE MOS MINS FOR OVERNIGHT LOWS...AS MODELS
HAVE INITIALIZED SNOW COVER WHICH DID NOT ACTUALLY MATERIALIZE FROM
SATURDAY NIGHT. (WRF-NAM FOR INSTANCE HAS A 2-3 INCH STRIPE
INITIALIZED FROM BUREAU COUNTY TO MCHENRY COUNTY IN NORTHERN IL).
MEDIUM RANGE...MONDAY THROUGH THURSDAY...
SURFACE HIGH PRESSURE SPREADS ACROSS THE AREA ON MONDAY AS UPPER
TROUGH CURRENTLY ACROSS THE MISSISSIPPI VALLEY LIFTS NORTHEAST AND
AWAY FROM THE REGION. SPLIT UPPER FLOW FOCUSES ANY SIGNIFICANT
SENSIBLE WEATHER OVER THE SOUTHWESTERN CONUS WHERE A CLOSED UPPER
LOW DEVELOPS TONIGHT/MONDAY...AND ACROSS THE PACIFIC NORTHWEST WHERE
A STRONG UPPER JET STREAK MOVES IN OFF THE NORTH PACIFIC. THIS JET
EVENTUALLY LEADS TO A DEEPENING AREA OF SURFACE LOW PRESSURE IN THE
LEE OF THE CANADIAN ROCKIES WHICH MOVES EAST ACROSS ONTARIO THROUGH
EARLY WEDNESDAY. SURFACE HIGH PRESSURE RIDGE ACROSS THE MIDWEST
MONDAY/TUESDAY IS THUS DISPLACED SOUTHWARD AS PRESSURE FALLS DEVELOP
ACROSS THE UPPER MIDWEST AND NORTHERN LAKES IN ASSOCIATION WITH THE
CANADIAN LOW. DRY AND SEASONABLY COOL/COLD WEATHER WILL BE THE RULE
EARLY IN THE WEEK...MODERATING BACK TO SLIGHTLY ABOVE NORMAL TEMPS
IN THE 30S BY MID-WEEK AS WEST/SOUTHWEST FLOW INCREASES NORTH OF THE
RETREATING SURFACE RIDGE AND SOUTH OF THE ONTARIO LOW PRESSURE
SYSTEM. SURFACE COLD FRONT THEN TRAILS THE CANADIAN LOW ACROSS THE
CWA WEDNESDAY NIGHT...RESULTING IN COLDER TEMPS CLOSER TO NORMAL
(UPPER 20S) FOR THURSDAY. FRONT DOES NOT MAKE MUCH OF A SOUTHWARD
PUSH HOWEVER AND REALLY ONLY PROVIDES A GLANCING BRUSH OF COLDER AIR
AS THE MID/UPPER LEVEL FLOW BECOMES MORE WESTERLY. VARIOUS GUIDANCE
MAINTAIN VERY DRY MOISTURE PROFILES ACROSS THE MIDWEST THROUGH
MID-WEEK...RESULTING IN LITTLE/NO QPF EVEN WITH THE FROPA LATE
WEDNESDAY. THEREFORE IT APPEARS CHICAGO/S STREAK OF DAYS WITHOUT A 1
INCH SNOWFALL WILL CONTINUE THROUGH MID-JANUARY AT LEAST.
LONGER RANGE...FRIDAY-SUNDAY...
GUIDANCE REMAIN IN PRETTY GOOD AGREEMENT IN MAINTAINING
WEST-NORTHWEST FLOW ALOFT FRIDAY...BEFORE GRADUALLY AMPLIFYING LARGE
SCALE UPPER TROUGH OVER THE EASTERN HALF OF NORTH AMERICA THROUGH
THE WORK OF A COUPLE DEEP SHORT WAVE TROUGHS THROUGH THE WEEKEND.
COLDER TREND IN TEMPS BEGINS SUNDAY...THE LAST DAY OF THIS FORECAST
PACKAGE...THOUGH MODEL TRENDS CONTINUE TO SUGGEST A PLUNGE OF TRUE
BITTER COLD ARCTIC AIR MONDAY/TUESDAY OF THE FOLLOWING WEEK.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LOWER END MVFR CEILINGS IMPROVING TO UPPER END OF MVFR RANGE BY
LATE AFTERNOON...GOING VFR BY EARLY EVENING.
* LIGHT SNOW AT MDW ENDING MID AFTERNOON WITH MINIMAL IF ANY
ACCUMULATION.
* NNW WIND INCREASING SLIGHTLY LATE AFTERNOON AND THIS EVENING...
BECOMING MODESTLY GUSTY 16-18KT THIS EVENING.
TRS
//DISCUSSION...UPDATED 18Z...
AS RAP OUTPUT CONTINUES TO DO A DECENT JOB IN HANDLING LOCATION
OF REFLECTIVITY HAVE FOLLOWED LATEST AVAILABLE VERSION /16Z/ AS
BASIS OF AFTERNOON AND EARLY EVENING FORECAST.
A SHORT WAVE HAS LIFTED FROM OVER FAR NORTHEAST TX AND SOUTHWEST
OK TO NORTHEASTERN AR AND SOUTHEASTERN MO DURING THE MORNING...
AND IS PROGGED TO MOVE NORTHEAST TO NORTHERN IL BY 00Z. HEAVIEST
PRECIPITATION WAS WELL TO THE SE THROUGH SW OF THE REGION...
CLOSER TO THE LOWER LEVEL BAROCLINIC ZONE. FURTHER NORTH...RADAR
ECHOES CONTINUE TO ADVANCE FROM CENTRAL IL TO THE FAR SOUTH TIP
OF LAKE MI AND NORTHWEST AND WEST CENTRAL IN AS THE SHORT WAVE
APPROACHES.
LOOP OF THE RAP COMPOSITE REFLECTIVITY FORECASTS SHOWS THE
NORTHWESTERN EDGE OF THE PRECIPITATION SHIELD MAKING NO FURTHER
NORTHWARD PROGRESS THIS AFTERNOON AND JUST GLANCING MDW BEFORE
MOVING OFF TO THE EAST BY EVENING AS SOUTHWEST WINDS VEER TO
WEST-SOUTHWEST AND WESTERLY IN THE LAYER FROM 1.5 TO 2.5 KM AGL
AND ADVECTING IN COLDER AND DRIER AIR FOLLOWING AN 850 HPA TROUGH
AXIS. THIS WILL ALSO RESULT IN SUBSIDENCE IN THE LOWER LAYERS AND
ANTICIPATE LOSS OF THE MVFR CEILINGS BY EARLY TO MID EVENING.
AS THE 700 HPA TROUGH MOVES ACROSS THE LOCAL AREA LATE THIS
EVENING SKIES SHOULD BECOME SKC TO SCT AS SUBSIDENCE EXPANDS UP
IN TO THE UPPER LEVELS.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN CEILING TRENDS.
* HIGH CONFIDENCE IN AREA OF -SN REMAINING JUST TO NORTHEAST
TROUGH SOUTHWEST OF ORD VICINITY.
* HIGH CONFIDENCE LIGHT SNOW ENDING AT MDW AROUND 22Z.
* HIGH CONFIDENCE IN WIND TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
245 PM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LIKELY FOR TUESDAY AFTERNOON THROUGH WEDNESDAY.
THIS AFTERNOON...LOW PRESSURE LIES OVER SOUTHERN QUEBEC WITH A
COLD FRONT EXTENDING SOUTHWEST INTO THE LOWER MISSISSIPPI
VALLEY...WITH HIGH PRESSURE SPRAWLING OVER THE NORTHERN AND CENTRAL
PLAINS. OVERNIGHT TONIGHT...THE LOW WILL LIFT NORTHEAST THROUGH
SOUTHERN QUEBEC WHILE THE COLD FRONT PUSHES THROUGH THE UPPER OHIO
RIVER VALLEY TO THE MID ATLANTIC REGION. BY TUESDAY...THE HIGH
WILL SPREAD ACROSS THE MIDDLE MISSISSIPPI VALLEY...TOWARD THE OHIO
VALLEY. MEANWHILE ANOTHER LOW WILL DROP SOUTHEAST INTO
SASKATCHEWAN AND DEEPEN AS IT MOVES ACROSS THE NORTHERN GREAT
LAKES REGION. THE COMBINATION OF NEARLY STATIONARY HIGH PRESSURE
OVER THE OHIO VALLEY...THE LOW DEEPENING AS IT SWINGS THROUGH THE
UPPER GREAT LAKES AND SOUTH CENTRAL CANADA AND AN APPROACHING
FRONTAL TROUGH ASSOCIATED WITH THE LOW WILL LEAD TO SOUTHWESTERLY
GALES DEVELOPING OVER THE NORTHERN PORTIONS OF THE LAKE BY TUESDAY
AFTERNOON...AND SPREADING TO THE SOUTHERN PORTIONS OF THE LAKE
THROUGH THE EVENING. SOUTHWEST GALES...TO 45 KT WILL PERSIST OVER
THE LAKE UNTIL THE COLD FRONT SWEEPS ACROSS THE LAKE LATE
WEDNESDAY AFTERNOON HIGH PRESSURE BUILDING ACROSS THE PLAINS
ALLOWS THE PRESSURE GRADIENT OVER THE LAKE TO RELAX ENOUGH FOR
WINDS TO DROP BELOW GALE FORCE.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM MONDAY.
GALE WATCH...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ669-LMZ671-LMZ868-LMZ870-LMZ872...3 PM TUESDAY TO 3 PM
WEDNESDAY.
GALE WATCH...LMZ080-LMZ673-LMZ675-LMZ777-LMZ779-LMZ874-LMZ876-
LMZ878...9 PM TUESDAY TO 3 PM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
242 PM CST SUN JAN 13 2013
.DISCUSSION...
1049 AM CST
FOR MORNING UPDATE...
ONLY MINOR CHANGES TO GOING FORECAST THIS MORNING.
FORECAST AREA REMAINS EAST OF LARGE SCALE UPPER TROUGH AXIS...
BENEATH SOUTHWEST-NORTHEAST ORIENTED UPPER JET AXIS AND LOW-MID
LEVEL BAROCLINIC ZONE WHICH STRETCHES FROM THE SOUTHERN PLAINS TO
THE GREAT LAKES REGION. SHORT WAVE TROUGH WHICH BROUGHT FREEZING
RAIN/SLEET TO THE AREA LAST NIGHT HAS LIFTED WELL TO THE NORTHEAST
OF THE AREA WITH ITS ASSOCIATED SURFACE LOW OVER WESTERN LAKE
ONTARIO AT MID-MORNING...WHILE ANOTHER JET STREAK AND LOW-AMPLITUDE
MID-LEVEL WAVE WAS NOTED UPSTREAM APPROACHING THE LOWER MISSOURI
VALLEY. THIS WAVE IS EXPECTED TO CONTINUE TO PROPAGATE NORTHEAST TO
THE GREAT LAKES THROUGH THIS EVENING...WITH WEAK SURFACE WAVE OVER
NORTHERN MISSISSIPPI RIPPLING NORTHEAST ALONG THE SURFACE FRONT INTO
THE UPPER OHIO VALLEY BY EARLY THIS EVENING.
12Z SOUNDINGS FROM LOCATIONS UPSTREAM INDICATE A LACK OF SOLID DEEP
MOISTURE AS BEST MOIST PLUME HAS NOW MOVED EAST OF OUR LOCAL AREA
PER WATER VAPOR IMAGERY...THOUGH A PERIOD OF MODERATE MID/UPPER
LEVEL FORCING IS DEPICTED BY VARIOUS MODELS WITH THE APPROACHING
WAVE WHICH WILL HELP MOISTEN AT LEAST PORTIONS OF THE COLUMN ACROSS
THE SOUTHEASTERN PARTS OF THE CWA THIS AFTERNOON. AREA OF INCREASING
RADAR RETURNS ACROSS SOUTHEAST MO AND SOUTHWESTERN IL ARE EXPECTED
TO SPREAD NORTHEAST ACROSS EAST CENTRAL IL AND NORTHWEST INDIANA
DURING THE MID-LATE AFTERNOON HOURS...WITH THE POTENTIAL FOR SOME
LIGHT SNOW AND PERHAPS EVEN A LITTLE LIGHT SLEET GIVEN LAYER OF ILX
12Z SOUNDING STILL AROUND 0 DEG C BETWEEN ABOUT 750-850 MB. 12Z
WRF-NAM TIME SECTIONS FOR GYY DEPICT SOME DECENT MID-LEVEL OMEGA
WITHIN GOOD DENDRITIC GROWTH ZONE FOR A TIME...AS WELL AS FAIRLY
STEEP LAPSE RATES AND EVEN A LITTLE ELEVATED CAPE ABOVE 600 MB...
THOUGH DRY LAYERS BELOW SUGGEST PRECIP MAY STRUGGLE TO GET TOO
IMPRESSIVE. STILL...POSSIBILITY EXISTS FOR SOME MINOR ACCUMS OF A
FEW TENTHS TO PERHAPS LESS THAN AN INCH ACROSS IL AREAS MAINLY EAST
OF I-57 AND EASTWARD INTO NORTHWEST INDIANA. FATHER WEST...ONLY A
FEW FLURRIES EXPECTED WITH DEEPER MOISTURE REALLY LACKING.
UPDATED NDFD GRIDS/ZFP ALREADY AVAILABLE.
RATZER
//PREV DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LOWER END MVFR CEILINGS IMPROVING TO UPPER END OF MVFR RANGE BY
LATE AFTERNOON...GOING VFR BY EARLY EVENING.
* LIGHT SNOW AT MDW ENDING MID AFTERNOON WITH MINIMAL IF ANY
ACCUMULATION.
* NNW WIND INCREASING SLIGHTLY LATE AFTERNOON AND THIS EVENING...
BECOMING MODESTLY GUSTY 16-18KT THIS EVENING.
TRS
//DISCUSSION...UPDATED 18Z...
AS RAP OUTPUT CONTINUES TO DO A DECENT JOB IN HANDLING LOCATION
OF REFLECTIVITY HAVE FOLLOWED LATEST AVAILABLE VERSION /16Z/ AS
BASIS OF AFTERNOON AND EARLY EVENING FORECAST.
A SHORT WAVE HAS LIFTED FROM OVER FAR NORTHEAST TX AND SOUTHWEST
OK TO NORTHEASTERN AR AND SOUTHEASTERN MO DURING THE MORNING...
AND IS PROGGED TO MOVE NORTHEAST TO NORTHERN IL BY 00Z. HEAVIEST
PRECIPITATION WAS WELL TO THE SE THROUGH SW OF THE REGION...
CLOSER TO THE LOWER LEVEL BAROCLINIC ZONE. FURTHER NORTH...RADAR
ECHOES CONTINUE TO ADVANCE FROM CENTRAL IL TO THE FAR SOUTH TIP
OF LAKE MI AND NORTHWEST AND WEST CENTRAL IN AS THE SHORT WAVE
APPROACHES.
LOOP OF THE RAP COMPOSITE REFLECTIVITY FORECASTS SHOWS THE
NORTHWESTERN EDGE OF THE PRECIPITATION SHIELD MAKING NO FURTHER
NORTHWARD PROGRESS THIS AFTERNOON AND JUST GLANCING MDW BEFORE
MOVING OFF TO THE EAST BY EVENING AS SOUTHWEST WINDS VEER TO
WEST-SOUTHWEST AND WESTERLY IN THE LAYER FROM 1.5 TO 2.5 KM AGL
AND ADVECTING IN COLDER AND DRIER AIR FOLLOWING AN 850 HPA TROUGH
AXIS. THIS WILL ALSO RESULT IN SUBSIDENCE IN THE LOWER LAYERS AND
ANTICIPATE LOSS OF THE MVFR CEILINGS BY EARLY TO MID EVENING.
AS THE 700 HPA TROUGH MOVES ACROSS THE LOCAL AREA LATE THIS
EVENING SKIES SHOULD BECOME SKC TO SCT AS SUBSIDENCE EXPANDS UP
IN TO THE UPPER LEVELS.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN CEILING TRENDS.
* HIGH CONFIDENCE IN AREA OF -SN REMAINING JUST TO NORTHEAST
TROUGH SOUTHWEST OF ORD VICINITY.
* HIGH CONFIDENCE LIGHT SNOW ENDING AT MDW AROUND 22Z.
* HIGH CONFIDENCE IN WIND TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
245 PM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LIKELY FOR TUESDAY AFTERNOON THROUGH WEDNESDAY.
THIS AFTERNOON...LOW PRESSURE LIES OVER SOUTHERN QUEBEC WITH A
COLD FRONT EXTENDING SOUTHWEST INTO THE LOWER MISSISSIPPI
VALLEY...WITH HIGH PRESSURE SPRAWLING OVER THE NORTHERN AND CENTRAL
PLAINS. OVERNIGHT TONIGHT...THE LOW WILL LIFT NORTHEAST THROUGH
SOUTHERN QUEBEC WHILE THE COLD FRONT PUSHES THROUGH THE UPPER OHIO
RIVER VALLEY TO THE MID ATLANTIC REGION. BY TUESDAY...THE HIGH
WILL SPREAD ACROSS THE MIDDLE MISSISSIPPI VALLEY...TOWARD THE OHIO
VALLEY. MEANWHILE ANOTHER LOW WILL DROP SOUTHEAST INTO
SASKATCHEWAN AND DEEPEN AS IT MOVES ACROSS THE NORTHERN GREAT
LAKES REGION. THE COMBINATION OF NEARLY STATIONARY HIGH PRESSURE
OVER THE OHIO VALLEY...THE LOW DEEPENING AS IT SWINGS THROUGH THE
UPPER GREAT LAKES AND SOUTH CENTRAL CANADA AND AN APPROACHING
FRONTAL TROUGH ASSOCIATED WITH THE LOW WILL LEAD TO SOUTHWESTERLY
GALES DEVELOPING OVER THE NORTHERN PORTIONS OF THE LAKE BY TUESDAY
AFTERNOON...AND SPREADING TO THE SOUTHERN PORTIONS OF THE LAKE
THROUGH THE EVENING. SOUTHWEST GALES...TO 45 KT WILL PERSIST OVER
THE LAKE UNTIL THE COLD FRONT SWEEPS ACROSS THE LAKE LATE
WEDNESDAY AFTERNOON HIGH PRESSURE BUILDING ACROSS THE PLAINS
ALLOWS THE PRESSURE GRADIENT OVER THE LAKE TO RELAX ENOUGH FOR
WINDS TO DROP BELOW GALE FORCE.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM MONDAY.
GALE WATCH...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ669-LMZ671-LMZ868-LMZ870-LMZ872...3 PM TUESDAY TO 3 PM
WEDNESDAY.
GALE WATCH...LMZ080-LMZ673-LMZ675-LMZ777-LMZ779-LMZ874-LMZ876-
LMZ878...9 PM TUESDAY TO 3 PM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
158 PM CST SUN JAN 13 2013
.DISCUSSION...
1049 AM CST
FOR MORNING UPDATE...
ONLY MINOR CHANGES TO GOING FORECAST THIS MORNING.
FORECAST AREA REMAINS EAST OF LARGE SCALE UPPER TROUGH AXIS...
BENEATH SOUTHWEST-NORTHEAST ORIENTED UPPER JET AXIS AND LOW-MID
LEVEL BAROCLINIC ZONE WHICH STRETCHES FROM THE SOUTHERN PLAINS TO
THE GREAT LAKES REGION. SHORT WAVE TROUGH WHICH BROUGHT FREEZING
RAIN/SLEET TO THE AREA LAST NIGHT HAS LIFTED WELL TO THE NORTHEAST
OF THE AREA WITH ITS ASSOCIATED SURFACE LOW OVER WESTERN LAKE
ONTARIO AT MID-MORNING...WHILE ANOTHER JET STREAK AND LOW-AMPLITUDE
MID-LEVEL WAVE WAS NOTED UPSTREAM APPROACHING THE LOWER MISSOURI
VALLEY. THIS WAVE IS EXPECTED TO CONTINUE TO PROPAGATE NORTHEAST TO
THE GREAT LAKES THROUGH THIS EVENING...WITH WEAK SURFACE WAVE OVER
NORTHERN MISSISSIPPI RIPPLING NORTHEAST ALONG THE SURFACE FRONT INTO
THE UPPER OHIO VALLEY BY EARLY THIS EVENING.
12Z SOUNDINGS FROM LOCATIONS UPSTREAM INDICATE A LACK OF SOLID DEEP
MOISTURE AS BEST MOIST PLUME HAS NOW MOVED EAST OF OUR LOCAL AREA
PER WATER VAPOR IMAGERY...THOUGH A PERIOD OF MODERATE MID/UPPER
LEVEL FORCING IS DEPICTED BY VARIOUS MODELS WITH THE APPROACHING
WAVE WHICH WILL HELP MOISTEN AT LEAST PORTIONS OF THE COLUMN ACROSS
THE SOUTHEASTERN PARTS OF THE CWA THIS AFTERNOON. AREA OF INCREASING
RADAR RETURNS ACROSS SOUTHEAST MO AND SOUTHWESTERN IL ARE EXPECTED
TO SPREAD NORTHEAST ACROSS EAST CENTRAL IL AND NORTHWEST INDIANA
DURING THE MID-LATE AFTERNOON HOURS...WITH THE POTENTIAL FOR SOME
LIGHT SNOW AND PERHAPS EVEN A LITTLE LIGHT SLEET GIVEN LAYER OF ILX
12Z SOUNDING STILL AROUND 0 DEG C BETWEEN ABOUT 750-850 MB. 12Z
WRF-NAM TIME SECTIONS FOR GYY DEPICT SOME DECENT MID-LEVEL OMEGA
WITHIN GOOD DENDRITIC GROWTH ZONE FOR A TIME...AS WELL AS FAIRLY
STEEP LAPSE RATES AND EVEN A LITTLE ELEVATED CAPE ABOVE 600 MB...
THOUGH DRY LAYERS BELOW SUGGEST PRECIP MAY STRUGGLE TO GET TOO
IMPRESSIVE. STILL...POSSIBILITY EXISTS FOR SOME MINOR ACCUMS OF A
FEW TENTHS TO PERHAPS LESS THAN AN INCH ACROSS IL AREAS MAINLY EAST
OF I-57 AND EASTWARD INTO NORTHWEST INDIANA. FATHER WEST...ONLY A
FEW FLURRIES EXPECTED WITH DEEPER MOISTURE REALLY LACKING.
UPDATED NDFD GRIDS/ZFP ALREADY AVAILABLE.
RATZER
//PREV DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LOWER END MVFR CEILINGS IMPROVING TO UPPER END OF MVFR RANGE BY
LATE AFTERNOON...GOING VFR BY EARLY EVENING.
* LIGHT SNOW AT MDW ENDING MID AFTERNOON WITH MINIMAL IF ANY
ACCUMULATION.
* NNW WIND INCREASING SLIGHTLY LATE AFTERNOON AND THIS EVENING...
BECOMING MODESTLY GUSTY 16-18KT THIS EVENING.
TRS
//DISCUSSION...UPDATED 18Z...
AS RAP OUTPUT CONTINUES TO DO A DECENT JOB IN HANDLING LOCATION
OF REFLECTIVITY HAVE FOLLOWED LATEST AVAILABLE VERSION /16Z/ AS
BASIS OF AFTERNOON AND EARLY EVENING FORECAST.
A SHORT WAVE HAS LIFTED FROM OVER FAR NORTHEAST TX AND SOUTHWEST
OK TO NORTHEASTERN AR AND SOUTHEASTERN MO DURING THE MORNING...
AND IS PROGGED TO MOVE NORTHEAST TO NORTHERN IL BY 00Z. HEAVIEST
PRECIPITATION WAS WELL TO THE SE THROUGH SW OF THE REGION...
CLOSER TO THE LOWER LEVEL BAROCLINIC ZONE. FURTHER NORTH...RADAR
ECHOES CONTINUE TO ADVANCE FROM CENTRAL IL TO THE FAR SOUTH TIP
OF LAKE MI AND NORTHWEST AND WEST CENTRAL IN AS THE SHORT WAVE
APPROACHES.
LOOP OF THE RAP COMPOSITE REFLECTIVITY FORECASTS SHOWS THE
NORTHWESTERN EDGE OF THE PRECIPITATION SHIELD MAKING NO FURTHER
NORTHWARD PROGRESS THIS AFTERNOON AND JUST GLANCING MDW BEFORE
MOVING OFF TO THE EAST BY EVENING AS SOUTHWEST WINDS VEER TO
WEST-SOUTHWEST AND WESTERLY IN THE LAYER FROM 1.5 TO 2.5 KM AGL
AND ADVECTING IN COLDER AND DRIER AIR FOLLOWING AN 850 HPA TROUGH
AXIS. THIS WILL ALSO RESULT IN SUBSIDENCE IN THE LOWER LAYERS AND
ANTICIPATE LOSS OF THE MVFR CEILINGS BY EARLY TO MID EVENING.
AS THE 700 HPA TROUGH MOVES ACROSS THE LOCAL AREA LATE THIS
EVENING SKIES SHOULD BECOME SKC TO SCT AS SUBSIDENCE EXPANDS UP
IN TO THE UPPER LEVELS.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN CEILING TRENDS.
* HIGH CONFIDENCE IN AREA OF -SN REMAINING JUST TO NORTHEAST
TROUGH SOUTHWEST OF ORD VICINITY.
* HIGH CONFIDENCE LIGHT SNOW ENDING AT MDW AROUND 22Z.
* HIGH CONFIDENCE IN WIND TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
120 PM CST SUN JAN 13 2013
.DISCUSSION...
1049 AM CST
FOR MORNING UPDATE...
ONLY MINOR CHANGES TO GOING FORECAST THIS MORNING.
FORECAST AREA REMAINS EAST OF LARGE SCALE UPPER TROUGH AXIS...
BENEATH SOUTHWEST-NORTHEAST ORIENTED UPPER JET AXIS AND LOW-MID
LEVEL BAROCLINIC ZONE WHICH STRETCHES FROM THE SOUTHERN PLAINS TO
THE GREAT LAKES REGION. SHORT WAVE TROUGH WHICH BROUGHT FREEZING
RAIN/SLEET TO THE AREA LAST NIGHT HAS LIFTED WELL TO THE NORTHEAST
OF THE AREA WITH ITS ASSOCIATED SURFACE LOW OVER WESTERN LAKE
ONTARIO AT MID-MORNING...WHILE ANOTHER JET STREAK AND LOW-AMPLITUDE
MID-LEVEL WAVE WAS NOTED UPSTREAM APPROACHING THE LOWER MISSOURI
VALLEY. THIS WAVE IS EXPECTED TO CONTINUE TO PROPAGATE NORTHEAST TO
THE GREAT LAKES THROUGH THIS EVENING...WITH WEAK SURFACE WAVE OVER
NORTHERN MISSISSIPPI RIPPLING NORTHEAST ALONG THE SURFACE FRONT INTO
THE UPPER OHIO VALLEY BY EARLY THIS EVENING.
12Z SOUNDINGS FROM LOCATIONS UPSTREAM INDICATE A LACK OF SOLID DEEP
MOISTURE AS BEST MOIST PLUME HAS NOW MOVED EAST OF OUR LOCAL AREA
PER WATER VAPOR IMAGERY...THOUGH A PERIOD OF MODERATE MID/UPPER
LEVEL FORCING IS DEPICTED BY VARIOUS MODELS WITH THE APPROACHING
WAVE WHICH WILL HELP MOISTEN AT LEAST PORTIONS OF THE COLUMN ACROSS
THE SOUTHEASTERN PARTS OF THE CWA THIS AFTERNOON. AREA OF INCREASING
RADAR RETURNS ACROSS SOUTHEAST MO AND SOUTHWESTERN IL ARE EXPECTED
TO SPREAD NORTHEAST ACROSS EAST CENTRAL IL AND NORTHWEST INDIANA
DURING THE MID-LATE AFTERNOON HOURS...WITH THE POTENTIAL FOR SOME
LIGHT SNOW AND PERHAPS EVEN A LITTLE LIGHT SLEET GIVEN LAYER OF ILX
12Z SOUNDING STILL AROUND 0 DEG C BETWEEN ABOUT 750-850 MB. 12Z
WRF-NAM TIME SECTIONS FOR GYY DEPICT SOME DECENT MID-LEVEL OMEGA
WITHIN GOOD DENDRITIC GROWTH ZONE FOR A TIME...AS WELL AS FAIRLY
STEEP LAPSE RATES AND EVEN A LITTLE ELEVATED CAPE ABOVE 600 MB...
THOUGH DRY LAYERS BELOW SUGGEST PRECIP MAY STRUGGLE TO GET TOO
IMPRESSIVE. STILL...POSSIBILITY EXISTS FOR SOME MINOR ACCUMS OF A
FEW TENTHS TO PERHAPS LESS THAN AN INCH ACROSS IL AREAS MAINLY EAST
OF I-57 AND EASTWARD INTO NORTHWEST INDIANA. FATHER WEST...ONLY A
FEW FLURRIES EXPECTED WITH DEEPER MOISTURE REALLY LACKING.
UPDATED NDFD GRIDS/ZFP ALREADY AVAILABLE.
RATZER
//PREV DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LOWER END MVFR CEILINGS IMPROVING TO UPPER END OF MVFR RANGE BY
LATE AFTERNOON...GOING VFR BY EARLY EVENING.
* SLIGHT CHANCE OF A LITTLE VERY LIGHT SNOW OR FLURRIES THIS
AFTERNOON AT ORD WHILE VERY LIGHT SNOW LIKELY AT MDW BUT NO
SIGNIFICANT REDUCTIONS IN VISIBILITY AT EITHER TERMINAL.
* NNW WIND INCREASING SLIGHTLY THIS AFTERNOON AND BECOMING
MODESTLY GUSTY TO 16-18KT LATER AFTERNOON.
TRS
//DISCUSSION...UPDATED 18Z...
AS RAP OUTPUT CONTINUES TO DO A DECENT JOB IN HANDLING LOCATION
OF REFLECTIVITY HAVE FOLLOWED LATEST AVAILABLE VERSION /16Z/ AS
BASIS OF AFTERNOON AND EARLY EVENING FORECAST.
A SHORT WAVE HAS LIFTED FROM OVER FAR NORTHEAST TX AND SOUTHWEST
OK TO NORTHEASTERN AR AND SOUTHEASTERN MO DURING THE MORNING...
AND IS PROGGED TO MOVE NORTHEAST TO NORTHERN IL BY 00Z. HEAVIEST
PRECIPITATION WAS WELL TO THE SE THROUGH SW OF THE REGION...
CLOSER TO THE LOWER LEVEL BAROCLINIC ZONE. FURTHER NORTH...RADAR
ECHOES CONTINUE TO ADVANCE FROM CENTRAL IL TO THE FAR SOUTH TIP
OF LAKE MI AND NORTHWEST AND WEST CENTRAL IN AS THE SHORT WAVE
APPROACHES.
LOOP OF THE RAP COMPOSITE REFLECTIVITY FORECASTS SHOWS THE
NORTHWESTERN EDGE OF THE PRECIPITATION SHIELD MAKING NO FURTHER
NORTHWARD PROGRESS THIS AFTERNOON AND JUST GLANCING MDW BEFORE
MOVING OFF TO THE EAST BY EVENING AS SOUTHWEST WINDS VEER TO
WEST-SOUTHWEST AND WESTERLY IN THE LAYER FROM 1.5 TO 2.5 KM AGL
AND ADVECTING IN COLDER AND DRIER AIR FOLLOWING AN 850 HPA TROUGH
AXIS. THIS WILL ALSO RESULT IN SUBSIDENCE IN THE LOWER LAYERS AND
ANTICIPATE LOSS OF THE MVFR CEILINGS BY EARLY TO MID EVENING.
AS THE 700 HPA TROUGH MOVES ACROSS THE LOCAL AREA LATE THIS
EVENING SKIES SHOULD BECOME SKC TO SCT AS SUBSIDENCE EXPANDS UP
IN TO THE UPPER LEVELS.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN CEILING TRENDS.
* HIGH CONFIDENCE IN AREA OF -SN MAINLY NORTHEAST TROUGH SOUTHWEST
OF ORD VICINITY.
* HIGH CONFIDENCE IN P6SM VISIBILITY AT ORD.
* MEDIUM CONFIDENCE OF P6SM VISIBILITY AT MDW THIS AFTERNOON.
* HIGH CONFIDENCE IN P6SM VISIBILITY AT MDW TONIGHT INTO MONDAY.
* HIGH CONFIDENCE IN WIND TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1050 AM CST SUN JAN 13 2013
.DISCUSSION...
1049 AM CST
FOR MORNING UPDATE...
ONLY MINOR CHANGES TO GOING FORECAST THIS MORNING.
FORECAST AREA REMAINS EAST OF LARGE SCALE UPPER TROUGH AXIS...
BENEATH SOUTHWEST-NORTHEAST ORIENTED UPPER JET AXIS AND LOW-MID
LEVEL BAROCLINIC ZONE WHICH STRETCHES FROM THE SOUTHERN PLAINS TO
THE GREAT LAKES REGION. SHORT WAVE TROUGH WHICH BROUGHT FREEZING
RAIN/SLEET TO THE AREA LAST NIGHT HAS LIFTED WELL TO THE NORTHEAST
OF THE AREA WITH ITS ASSOCIATED SURFACE LOW OVER WESTERN LAKE
ONTARIO AT MID-MORNING...WHILE ANOTHER JET STREAK AND LOW-AMPLITUDE
MID-LEVEL WAVE WAS NOTED UPSTREAM APPROACHING THE LOWER MISSOURI
VALLEY. THIS WAVE IS EXPECTED TO CONTINUE TO PROPAGATE NORTHEAST TO
THE GREAT LAKES THROUGH THIS EVENING...WITH WEAK SURFACE WAVE OVER
NORTHERN MISSISSIPPI RIPPLING NORTHEAST ALONG THE SURFACE FRONT INTO
THE UPPER OHIO VALLEY BY EARLY THIS EVENING.
12Z SOUNDINGS FROM LOCATIONS UPSTREAM INDICATE A LACK OF SOLID DEEP
MOISTURE AS BEST MOIST PLUME HAS NOW MOVED EAST OF OUR LOCAL AREA
PER WATER VAPOR IMAGERY...THOUGH A PERIOD OF MODERATE MID/UPPER
LEVEL FORCING IS DEPICTED BY VARIOUS MODELS WITH THE APPROACHING
WAVE WHICH WILL HELP MOISTEN AT LEAST PORTIONS OF THE COLUMN ACROSS
THE SOUTHEASTERN PARTS OF THE CWA THIS AFTERNOON. AREA OF INCREASING
RADAR RETURNS ACROSS SOUTHEAST MO AND SOUTHWESTERN IL ARE EXPECTED
TO SPREAD NORTHEAST ACROSS EAST CENTRAL IL AND NORTHWEST INDIANA
DURING THE MID-LATE AFTERNOON HOURS...WITH THE POTENTIAL FOR SOME
LIGHT SNOW AND PERHAPS EVEN A LITTLE LIGHT SLEET GIVEN LAYER OF ILX
12Z SOUNDING STILL AROUND 0 DEG C BETWEEN ABOUT 750-850 MB. 12Z
WRF-NAM TIME SECTIONS FOR GYY DEPICT SOME DECENT MID-LEVEL OMEGA
WITHIN GOOD DENDRITIC GROWTH ZONE FOR A TIME...AS WELL AS FAIRLY
STEEP LAPSE RATES AND EVEN A LITTLE ELEVATED CAPE ABOVE 600 MB...
THOUGH DRY LAYERS BELOW SUGGEST PRECIP MAY STRUGGLE TO GET TOO
IMPRESSIVE. STILL...POSSIBILITY EXISTS FOR SOME MINOR ACCUMS OF A
FEW TENTHS TO PERHAPS LESS THAN AN INCH ACROSS IL AREAS MAINLY EAST
OF I-57 AND EASTWARD INTO NORTHWEST INDIANA. FATHER WEST...ONLY A
FEW FLURRIES EXPECTED WITH DEEPER MOISTURE REALLY LACKING.
UPDATED NDFD GRIDS/ZFP ALREADY AVAILABLE.
RATZER
&&
.PREV DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* LOW END MVFR CIGS...POSSIBLY BRIEFLY IFR...THROUGH EARLY THIS
AFTERNOON AND THEN GRADUAL IMPROVEMENT INTO EARLY THIS EVE.
* SMALL CHANCE FOR -SN THIS AFTERNOON MAINLY E-S OF IMMEDIATE MDW
AREA.
* WINDS INCREASING SLIGHTLY THIS AFTERNOON AND BECOMING GUSTS BY
MID TO LATE AFTERNOON.
MTF/TRS
//DISCUSSION...UPDATED 14Z...
RAP OUTPUT SEEMS TO HAVE HANDLING ECHO LOCATION OVER THE LAST FEW
HOURS AND HAS AN AREA EXPANDING FROM FAR SE MO NORTHEASTWARD
ACROSS SOUTHERN AND EASTERN IL INTO NORTHERN IN DURING MID
MORNING TO EARLY AFTERNOON. THIS KEEPS MOST IF NOT ALL
SIGNIFICANT PRECIPITATION TO THE E THROUGH SE OF ORD AND MDW...
WITH GYY HAVING BEST CHANCE OF SEEING SOME -SN MID TO LATE
AFTERNOON AS THE SHORT WAVE OVER FAR NE TX AND SW OK CONTINUES TO
LIFT NORTHEASTWARD TO THE MID MS VALLEY BY 14.00Z.
PREVIOUS DISCUSSION...UPDATED 12Z...
LOW PRESSURE OVER LAKE ERIE WILL CONTINUE TO PROGRESS NORTHEAST
TODAY. REMNANT AMPLE LOW-LEVEL MOISTURE AND SOME WEAK FORCING HAS
AIDED IN A RE-EXPANSION OF DRIZZLE THIS MORNING. THIS SHOULD BE
SOMEWHAT TRANSIENT...BUT WHERE IT OCCURS WILL BE ENOUGH TO
POTENTIALLY CREATE IFR CIGS AND VISBYS. A STRONG UPPER JET OVER
THE AREA WILL BRING A DISTURBANCE OVER THE REGION THIS AFTERNOON.
MOST OF THE LIGHT SNOW WITH THIS DURING THE AFTERNOON WILL REMAIN
TO THE SOUTHEAST OF THE AIRPORTS...WITH GYY AND MDW POTENTIALLY
BEING THE EXCEPTIONS. SMALL ACCUMULATION WILL BE POSSIBLE AT GYY.
LOW CIGS WILL BE STEADY THIS MORNING BEFORE LIKELY SHOWING SOME
IMPROVEMENT THIS AFTERNOON AS DRIER AIR PUSHES EASTWARD IN THE
BOUNDARY LAYER. WINDS WILL SLOWLY BACK TO WNW THIS AFTERNOON AND
INCREASE IN GUSTINESS AS COLD AIR ADVECTION INCREASES IN THE WAKE
OF THE WAVE.
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE IN CIG TRENDS.
* MEDIUM CONFIDENCE IN AREA OF -SN DURING MID TO LATE AFTERNOON
STAYING TO E THROUGH SE OF IMMEDIATE CHI AREA...POSSIBLY SOME
VERY LIGHT SNOW OR FLURRIES AT MDW.
* HIGH CONFIDENCE IN WIND TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1038 AM CST SUN JAN 13 2013
.DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* LOW END MVFR CIGS...POSSIBLY BRIEFLY IFR...THROUGH EARLY THIS
AFTERNOON AND THEN GRADUAL IMPROVEMENT INTO EARLY THIS EVE.
* SMALL CHANCE FOR -SN THIS AFTERNOON MAINLY E-S OF IMMEDIATE MDW
AREA.
* WINDS INCREASING SLIGHTLY THIS AFTERNOON AND BECOMING GUSTS BY
MID TO LATE AFTERNOON.
MTF/TRS
//DISCUSSION...UPDATED 14Z...
RAP OUTPUT SEEMS TO HAVE HANDLING ECHO LOCATION OVER THE LAST FEW
HOURS AND HAS AN AREA EXPANDING FROM FAR SE MO NORTHEASTWARD
ACROSS SOUTHERN AND EASTERN IL INTO NORTHERN IN DURING MID
MORNING TO EARLY AFTERNOON. THIS KEEPS MOST IF NOT ALL
SIGNIFICANT PRECIPITATION TO THE E THROUGH SE OF ORD AND MDW...
WITH GYY HAVING BEST CHANCE OF SEEING SOME -SN MID TO LATE
AFTERNOON AS THE SHORT WAVE OVER FAR NE TX AND SW OK CONTINUES TO
LIFT NORTHEASTWARD TO THE MID MS VALLEY BY 14.00Z.
PREVIOUS DISCUSSION...UPDATED 12Z...
LOW PRESSURE OVER LAKE ERIE WILL CONTINUE TO PROGRESS NORTHEAST
TODAY. REMNANT AMPLE LOW-LEVEL MOISTURE AND SOME WEAK FORCING HAS
AIDED IN A RE-EXPANSION OF DRIZZLE THIS MORNING. THIS SHOULD BE
SOMEWHAT TRANSIENT...BUT WHERE IT OCCURS WILL BE ENOUGH TO
POTENTIALLY CREATE IFR CIGS AND VISBYS. A STRONG UPPER JET OVER
THE AREA WILL BRING A DISTURBANCE OVER THE REGION THIS AFTERNOON.
MOST OF THE LIGHT SNOW WITH THIS DURING THE AFTERNOON WILL REMAIN
TO THE SOUTHEAST OF THE AIRPORTS...WITH GYY AND MDW POTENTIALLY
BEING THE EXCEPTIONS. SMALL ACCUMULATION WILL BE POSSIBLE AT GYY.
LOW CIGS WILL BE STEADY THIS MORNING BEFORE LIKELY SHOWING SOME
IMPROVEMENT THIS AFTERNOON AS DRIER AIR PUSHES EASTWARD IN THE
BOUNDARY LAYER. WINDS WILL SLOWLY BACK TO WNW THIS AFTERNOON AND
INCREASE IN GUSTINESS AS COLD AIR ADVECTION INCREASES IN THE WAKE
OF THE WAVE.
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE IN CIG TRENDS.
* MEDIUM CONFIDENCE IN AREA OF -SN DURING MID TO LATE AFTERNOON
STAYING TO E THROUGH SE OF IMMEDIATE CHI AREA...POSSIBLY SOME
VERY LIGHT SNOW OR FLURRIES AT MDW.
* HIGH CONFIDENCE IN WIND TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
248 PM EST SUN JAN 13 2013
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 326 AM EST SUN JAN 13 2013
COLD FRONT WILL SLOWLY SETTLE SOUTHEAST OF CENTRAL INDIANA TODAY
RESULTING IN THE END OF PRECIPITATION AFTER MIDNIGHT SUNDAY NIGHT
BUT NOT BEFORE HEAVY RAIN CHANGES OVER TO A WINTRY MIX FROM
NORTHWEST TO SOUTHEAST WITH MINOR ICE OR SNOW ACCUMULATION POSSIBLE.
MUCH COLDER MORE SEASONABLE AIR WILL FILTER IN ALONG WITH DRY
WEATHER THROUGH NEXT WEEKEND. THIS WILL ALLOW RIVER FLOODING TO RUN
ITS COURSE.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1049 AM EST SUN JAN 13 2013
RADAR MOSAIC AND OBSERVATIONS SHOW RAIN STILL FALLING OVER
SOUTHEASTERN FORECAST AREA WITH AREAS OF DRIZZLE OR VERY LIGHT
RAIN OVER THE REST OF THE AREA. AT 11 AM TEMPERATURES RANGED FROM
THE MID 40S IN THE SOUTHEAST TO RIGHT JUST BELOW THE FREEZING MARK
IN THE NORTHWEST. THE COLD FRONT HAS STALLED JUST SOUTH OF THE
AREA AND A SURFACE WAVE IS MOVING ALONG IT INTO THE AREA. THIS
WAVE IS KEEPING THE SUB-FREEZING AIR FROM ADVANCING INTO THE AREA.
FORECAST SOUNDINGS FROM THE RAPID REFRESH AND RAP AS WELL AS THE
NAM SHOW AN INTRUSION OF COLD AIR JUST ABOVE THE SURFACE FROM THE
NORTHWEST WITH A WARM LAYER ABOVE IT AND LOOKS LIKE IT COULD ALLOW
RAIN TO CHANGE OVER OR MIX WITH SLEET IN THE NORTHWEST OVER THE
NEXT COUPLE OF HOURS AND SPREADING SOUTHEAST FROM THERE. SNOW
COULD MIX IN AFTER 1 IN THE NORTHWEST BUT CHANGE OVER TO JUST SNOW
DOESN/T APPEAR LIKELY IN THE NORTHWEST UNTIL AFTER 4 PM. SURFACE
TEMPERATURES HOLDING FAIRLY STEADY OR JUST FALLING SLOWLY OVER THE
NEXT SEVERAL HOURS SO DO NOT SEE A WIDESPREAD RISK FOR FREEZING
RAIN. THE WESTERN COUNTIES WILL SEE THE GREATEST RISK FOR ANY KIND
OF FREEZING RAIN OR FREEZING DRIZZLE BUT STILL DO NOT EXPECT MUCH
IN THE WAY OF ANY ACCUMULATION OF ICE. SOUTHEASTERN COUNTIES CAN
JUST EXPECT RAIN TO INCREASE IN INTENSITY AND COVERAGE THROUGH THE
AFTERNOON AS THE SURFACE WAVE MOVES NORTHEAST ALONG THE FRONT.
WILL CONTINUE WITH THE FLOOD WATCH AS ADDITIONAL HEAVY RAIN COULD
EXACERBATE CURRENT FLOODING SITUATION ACROSS THE AREA...BUT NOT
ANTICIPATING MORE THAN UP TO AN ADDITIONAL HALF INCH IN THE
SOUTHEAST WITH PERHAPS A QUARTER INCH OR LESS NORTH OF I 70.
CHANGE OVER TO SNOW LOOKS FAIRLY LATE...PROBABLY NOT UNTIL THE
TONIGHT PERIOD IN THE CENTRAL AND SOUTH...AND IS FOLLOWED QUICKLY
BY ARRIVAL OF DRY AIR SO DO NOT EXPECT MUCH IN THE WAY OF
ACCUMULATION. COULD SEE LIGHT ACCUMULATIONS OF SLEET IN THE WEST.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 326 AM EST SUN JAN 13 2013
THE SHORT TERM FOCUS WILL BE MAINLY ON TEMPERATURES AS A VERY DRY
COLUMN WILL BE IN PLACE THROUGH THE PERIOD AS PLAINS HIGH PRESSURE
BUILDS IN ACROSS THE OHIO VALLEY AND LOWER GREAT LAKES RESULTING IN
LITTLE CLOUD COVER AND SLIGHTLY BELOW AVERAGE TEMPERATURES.
OVERALL...00Z MOS NUMBERS LOOK OK. THE ONLY CAVEAT IS THE NAM MOS
LOOKS SEVERAL DEGREES TOO WARM AT BMG BASED ON ITS OTHER FORECASTED
NUMBERS AND THE GFS MOS. ALLBLEND IS A GOOD PROXY. LOOK FOR
AFTERNOON HIGHS IN THE UPPER 20S TO THE MID 30S ON MONDAY AND IN THE
30S ON TUESDAY. OVERNIGHT LOWS WILL BE IN THE UPPER TEENS TO THE
LOWER 20S.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 248 PM EST SUN JAN 13 2013
DRY SEASONABLE PATTERN SETTING UP FOR THE TAIL END OF THE WEEK...
WITH GROWING SIGNS FOR MUCH COLDER AIR TO ARRIVE ACROSS CENTRAL
INDIANA BY EARLY NEXT WEEK.
UPPER LEVEL PATTERN WILL REMAIN HIGHLY AMPLIFIED THROUGH THE PERIOD
WITH THE POLAR VORTEX INCREASINGLY BECOME A FACTOR IN EXPECTED
WEATHER ACROSS THE OHIO VALLEY AS IT SLIDES TO NEAR JAMES BAY BY
LATE WEEK. UPPER RIDGE AXIS WILL ALIGN OFF THE U S WEST COAST FOR
MUCH OF THE EXTENDED WITH A DOWNSTREAM TROUGH ENCOMPASSING MUCH OF
THE EASTERN PART OF THE COUNTRY AND WITH TIME...AMPLIFYING DUE TO
THE LOCATION OF THE POLAR VORTEX OVER EASTERN CANADA. FOR CENTRAL
INDIANA...CYCLONIC NORTHWEST FLOW ALOFT WILL BRING A DRY COOL
PATTERN FOR LATE WEEK INTO THE WEEKEND. TEMPERATURES ARE LIKELY TO
BE NEAR NORMAL WITH HIGHS IN THE 30S...POSSIBLY WARMING INTO THE
LOWER 40S FRIDAY AND SATURDAY AS THE UPPER TROUGH RELAXES BRIEFLY.
EXTENDED MODEL GUIDANCE CONTINUES TO ADVERTISE A PIECE OF THE POLAR
VORTEX DIVING SOUTH NEAR THE END OF THE FORECAST PERIOD AND WHILE
THE INDIVIDUAL RUNS DIFFER ON TIMING AND LOCATION TO SOME DEGREE...
THE CONSENSUS SOLUTION AGREES ON A TREND TOWARDS A MUCH COLDER
AIRMASS EXPANDING INTO THE GREAT LAKES AND OHIO VALLEY LATE WEEKEND
INTO EARLY NEXT WEEK. CONFIDENCE CONTINUES TO GROW IN THIS SOLUTION
PLAYING OUT CONSIDERING THAT EXTENDED MODELS HAVE BEEN SHOWING THIS
POTENTIAL FOR SEVERAL DAYS NOW...AND THAT THE POLAR VORTEX REMAINS
OVER EASTERN CANADA. BOTH 12Z RUNS OF THE ECMWF/OP GFS TODAY SHOWING
850MB TEMPS TO NEAR -20C BY NEXT MONDAY/TUESDAY.
&&
.AVIATION /DISCUSSION FOR 131800Z TAF ISSUANCE/...
ISSUED AT 1218 PM EST SUN JAN 13 2013
VERY POOR FLYING CONDITIONS WILL CONTINUE THROUGHOUT THE AFTERNOON
AND EARLY EVENING AS PRECIPITATION SLOWLY MIXES WITH AND CHANGES
OVER TO PREDOMINANTLY SLEET AND SNOW. VFR CONDITIONS DEVELOPING
AFTER MIDNIGHT AND INTO MONDAY AS HIGH PRESSURE BUILDS IN.
COMPLEX FIRST SIX HOURS TO THE TAF FORECASTS WITH THE MAIN ISSUE
FOCUSED ON PRECIP TYPE AND ATTEMPTING TO TIME THE MIXING/
CHANGEOVER AT EACH SITE. SECONDARY SURFACE WAVE TRACKING INTO
SOUTHERN KENTUCKY WITH A LARGE PRECIP SHIELD EXPANDING BACK INTO
CENTRAL INDIANA FROM THE SOUTH. NEAR SURFACE SUBFREEZING TEMPS
ARE SLOWLY OVERSPREADING THE WABASH VALLEY EARLY THIS AFTERNOON
WHILE MUCH OF THE BOUNDARY LAYER REMAINS ABOVE FREEZING. THIS IS
WHERE THE CHALLENGE COMES IN FOR THE AFTERNOON AS NEAR SURFACE AIR
WILL COOL FASTER THAN THE BOUNDARY LAYER AS IT EXPANDS EAST ACROSS
THE FORECAST AREA. WITH THAT BEING SAID...THE TRACK AND PASSAGE OF
THE SURFACE WAVE JUST SOUTHEAST OF THE REGION OVER THE NEXT FEW
HOURS IS LIKELY TO SLOW EASTWARD ADVECTION OF COLDER AIR SOMEWHAT.
AT THIS POINT...SURFACE TEMPS AT OR JUST BELOW FREEZING AT KHUF
AND KLAF BOTH SUPPORT A FREEZING RAIN AND SLEET MIX TO BEGIN. AS
BOUNDARY LAYER AIR COOLS AND MOISTURE DEEPENS...PRECIP TYPE SHOULD
SHIFT MORE TO SLEET WITH SNOWFLAKES BEGINNING TO MIX IN BY 21Z. AT
KBMG AND KIND...TEMP PROFILES AND MODEL SOUNDINGS POINT TO
PRECIPITATION FALLING PREDOMINANTLY AS RAIN THROUGH 21Z. SLEET MAY
OCCASIONALLY MIX IN PRIOR TO THIS TIME AT BOTH SITES...BUT
POTENTIAL LOOKS LOW ENOUGH TO KEEP OUT OF THE TERMINALS. NEAR
SURFACE AIR SHOULD COOL ENOUGH AT KBMG AND KIND AFTER 21Z FOR
SLEET AND EVENTUALLY SNOW TO BECOME THE MAIN PRECIP TYPE AT BOTH
SITES. PRECIPITATION WILL END ABRUPTLY AT ALL SITES BETWEEN 00Z
AND 02Z AS THE SURFACE WAVE MOVES AWAY TO THE EAST. IFR AND LOWER
CONDITIONS WILL PERSIST ALL AFTERNOON AND INTO THE EVENING...WITH
IMPROVEMENTS TO MVFR LIKELY ONCE PRECIPITATION ENDS. NORTH-NORTHWEST
WINDS WILL BE SUSTAINED AT 10-15KTS THROUGH THE EVENING...WITH
OCCASIONAL GUSTS NEAR 20KTS.
HIGH PRESSURE WILL EXPAND INTO THE OHIO VALLEY OVERNIGHT WITH
DRIER AIR AND BROAD SUBSIDENCE ENABLING SKIES TO EVENTUALLY CLEAR.
PRESENCE OF A SHALLOW LAYER OF LOW LEVEL MOISTURE MAY SERVE TO
KEEP SCATTERED MVFR CEILINGS THROUGH DAYBREAK...BUT OVERALL TREND
WILL BE TOWARDS SKIES BECOMING MAINLY CLEAR. WINDS WILL VEER TO
NORTHERLY MONDAY MORNING AND DECREASE TO 5-10KTS.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL 4 PM EST THIS AFTERNOON FOR INZ030-031-036>042-
044>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...MK
NEAR TERM...CP
SHORT TERM...MK
LONG TERM....RYAN
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1218 PM EST SUN JAN 13 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 326 AM EST SUN JAN 13 2013
COLD FRONT WILL SLOWLY SETTLE SOUTHEAST OF CENTRAL INDIANA TODAY
RESULTING IN THE END OF PRECIPITATION AFTER MIDNIGHT SUNDAY NIGHT
BUT NOT BEFORE HEAVY RAIN CHANGES OVER TO A WINTRY MIX FROM
NORTHWEST TO SOUTHEAST WITH MINOR ICE OR SNOW ACCUMULATION POSSIBLE.
MUCH COLDER MORE SEASONABLE AIR WILL FILTER IN ALONG WITH DRY
WEATHER THROUGH NEXT WEEKEND. THIS WILL ALLOW RIVER FLOODING TO RUN
ITS COURSE.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1049 AM EST SUN JAN 13 2013
RADAR MOSAIC AND OBSERVATIONS SHOW RAIN STILL FALLING OVER
SOUTHEASTERN FORECAST AREA WITH AREAS OF DRIZZLE OR VERY LIGHT
RAIN OVER THE REST OF THE AREA. AT 11 AM TEMPERATURES RANGED FROM
THE MID 40S IN THE SOUTHEAST TO RIGHT JUST BELOW THE FREEZING MARK
IN THE NORTHWEST. THE COLD FRONT HAS STALLED JUST SOUTH OF THE
AREA AND A SURFACE WAVE IS MOVING ALONG IT INTO THE AREA. THIS
WAVE IS KEEPING THE SUB-FREEZING AIR FROM ADVANCING INTO THE AREA.
FORECAST SOUNDINGS FROM THE RAPID REFRESH AND RAP AS WELL AS THE
NAM SHOW AN INTRUSION OF COLD AIR JUST ABOVE THE SURFACE FROM THE
NORTHWEST WITH A WARM LAYER ABOVE IT AND LOOKS LIKE IT COULD ALLOW
RAIN TO CHANGE OVER OR MIX WITH SLEET IN THE NORTHWEST OVER THE
NEXT COUPLE OF HOURS AND SPREADING SOUTHEAST FROM THERE. SNOW
COULD MIX IN AFTER 1 IN THE NORTHWEST BUT CHANGE OVER TO JUST SNOW
DOESN/T APPEAR LIKELY IN THE NORTHWEST UNTIL AFTER 4 PM. SURFACE
TEMPERATURES HOLDING FAIRLY STEADY OR JUST FALLING SLOWLY OVER THE
NEXT SEVERAL HOURS SO DO NOT SEE A WIDESPREAD RISK FOR FREEZING
RAIN. THE WESTERN COUNTIES WILL SEE THE GREATEST RISK FOR ANY KIND
OF FREEZING RAIN OR FREEZING DRIZZLE BUT STILL DO NOT EXPECT MUCH
IN THE WAY OF ANY ACCUMULATION OF ICE. SOUTHEASTERN COUNTIES CAN
JUST EXPECT RAIN TO INCREASE IN INTENSITY AND COVERAGE THROUGH THE
AFTERNOON AS THE SURFACE WAVE MOVES NORTHEAST ALONG THE FRONT.
WILL CONTINUE WITH THE FLOOD WATCH AS ADDITIONAL HEAVY RAIN COULD
EXACERBATE CURRENT FLOODING SITUATION ACROSS THE AREA...BUT NOT
ANTICIPATING MORE THAN UP TO AN ADDITIONAL HALF INCH IN THE
SOUTHEAST WITH PERHAPS A QUARTER INCH OR LESS NORTH OF I 70.
CHANGE OVER TO SNOW LOOKS FAIRLY LATE...PROBABLY NOT UNTIL THE
TONIGHT PERIOD IN THE CENTRAL AND SOUTH...AND IS FOLLOWED QUICKLY
BY ARRIVAL OF DRY AIR SO DO NOT EXPECT MUCH IN THE WAY OF
ACCUMULATION. COULD SEE LIGHT ACCUMULATIONS OF SLEET IN THE WEST.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 326 AM EST SUN JAN 13 2013
THE SHORT TERM FOCUS WILL BE MAINLY ON TEMPERATURES AS A VERY DRY
COLUMN WILL BE IN PLACE THROUGH THE PERIOD AS PLAINS HIGH PRESSURE
BUILDS IN ACROSS THE OHIO VALLEY AND LOWER GREAT LAKES RESULTING IN
LITTLE CLOUD COVER AND SLIGHTLY BELOW AVERAGE TEMPERATURES.
OVERALL...00Z MOS NUMBERS LOOK OK. THE ONLY CAVEAT IS THE NAM MOS
LOOKS SEVERAL DEGREES TOO WARM AT BMG BASED ON ITS OTHER FORECASTED
NUMBERS AND THE GFS MOS. ALLBLEND IS A GOOD PROXY. LOOK FOR
AFTERNOON HIGHS IN THE UPPER 20S TO THE MID 30S ON MONDAY AND IN THE
30S ON TUESDAY. OVERNIGHT LOWS WILL BE IN THE UPPER TEENS TO THE
LOWER 20S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
ISSUED AT 329 AM EST SUN JAN 13 2013
A DRY EXTENDED PERIOD IS STILL EXPECTED FOR CENTRAL INDIANA
DESPITE A FEW DISTURBANCES IN THE MEAN FLOW ON WEDNESDAY AND
FRIDAY. THE EURO IS NOW IN LINE WITH THE GFS IN REGARD TO SOME
PRECIP ACROSS NORTHERN INDIANA ON WEDNESDAY...BUT LATEST
INITIALIZATION KEEPS THE FORECAST DRY AND THIS LOOKS GOOD SINCE
PRECIP WILL STAY NORTH OF FORECAST AREA. ANOTHER LOW WILL PASS
OVER THE GREAT LAKES REGION AT THE END OF THE WEEK...BUT ALL
PRECIP WILL STAY WELL NORTH OF CENTRAL INDIANA WITH THIS
DISTURBANCE AS WELL. TEMPS WILL BE CLOSE TO NORMAL...BUT A MUCH
MORE FRIGID AIRMASS IS PROGGED FOR THE REGION BEYOND THE LONG
TERM PERIOD.
&&
.AVIATION /DISCUSSION FOR 131800Z TAF ISSUANCE/...
ISSUED AT 1218 PM EST SUN JAN 13 2013
VERY POOR FLYING CONDITIONS WILL CONTINUE THROUGHOUT THE AFTERNOON
AND EARLY EVENING AS PRECIPITATION SLOWLY MIXES WITH AND CHANGES
OVER TO PREDOMINANTLY SLEET AND SNOW. VFR CONDITIONS DEVELOPING
AFTER MIDNIGHT AND INTO MONDAY AS HIGH PRESSURE BUILDS IN.
COMPLEX FIRST SIX HOURS TO THE TAF FORECASTS WITH THE MAIN ISSUE
FOCUSED ON PRECIP TYPE AND ATTEMPTING TO TIME THE MIXING/
CHANGEOVER AT EACH SITE. SECONDARY SURFACE WAVE TRACKING INTO
SOUTHERN KENTUCKY WITH A LARGE PRECIP SHIELD EXPANDING BACK INTO
CENTRAL INDIANA FROM THE SOUTH. NEAR SURFACE SUBFREEZING TEMPS
ARE SLOWLY OVERSPREADING THE WABASH VALLEY EARLY THIS AFTERNOON
WHILE MUCH OF THE BOUNDARY LAYER REMAINS ABOVE FREEZING. THIS IS
WHERE THE CHALLENGE COMES IN FOR THE AFTERNOON AS NEAR SURFACE AIR
WILL COOL FASTER THAN THE BOUNDARY LAYER AS IT EXPANDS EAST ACROSS
THE FORECAST AREA. WITH THAT BEING SAID...THE TRACK AND PASSAGE OF
THE SURFACE WAVE JUST SOUTHEAST OF THE REGION OVER THE NEXT FEW
HOURS IS LIKELY TO SLOW EASTWARD ADVECTION OF COLDER AIR SOMEWHAT.
AT THIS POINT...SURFACE TEMPS AT OR JUST BELOW FREEZING AT KHUF
AND KLAF BOTH SUPPORT A FREEZING RAIN AND SLEET MIX TO BEGIN. AS
BOUNDARY LAYER AIR COOLS AND MOISTURE DEEPENS...PRECIP TYPE SHOULD
SHIFT MORE TO SLEET WITH SNOWFLAKES BEGINNING TO MIX IN BY 21Z. AT
KBMG AND KIND...TEMP PROFILES AND MODEL SOUNDINGS POINT TO
PRECIPITATION FALLING PREDOMINANTLY AS RAIN THROUGH 21Z. SLEET MAY
OCCASIONALLY MIX IN PRIOR TO THIS TIME AT BOTH SITES...BUT
POTENTIAL LOOKS LOW ENOUGH TO KEEP OUT OF THE TERMINALS. NEAR
SURFACE AIR SHOULD COOL ENOUGH AT KBMG AND KIND AFTER 21Z FOR
SLEET AND EVENTUALLY SNOW TO BECOME THE MAIN PRECIP TYPE AT BOTH
SITES. PRECIPITATION WILL END ABRUPTLY AT ALL SITES BETWEEN 00Z
AND 02Z AS THE SURFACE WAVE MOVES AWAY TO THE EAST. IFR AND LOWER
CONDITIONS WILL PERSIST ALL AFTERNOON AND INTO THE EVENING...WITH
IMPROVEMENTS TO MVFR LIKELY ONCE PRECIPITATION ENDS. NORTH-NORTHWEST
WINDS WILL BE SUSTAINED AT 10-15KTS THROUGH THE EVENING...WITH
OCCASIONAL GUSTS NEAR 20KTS.
HIGH PRESSURE WILL EXPAND INTO THE OHIO VALLEY OVERNIGHT WITH
DRIER AIR AND BROAD SUBSIDENCE ENABLING SKIES TO EVENTUALLY CLEAR.
PRESENCE OF A SHALLOW LAYER OF LOW LEVEL MOISTURE MAY SERVE TO
KEEP SCATTERED MVFR CEILINGS THROUGH DAYBREAK...BUT OVERALL TREND
WILL BE TOWARDS SKIES BECOMING MAINLY CLEAR. WINDS WILL VEER TO
NORTHERLY MONDAY MORNING AND DECREASE TO 5-10KTS.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL 4 PM EST THIS AFTERNOON FOR INZ030-031-036>042-
044>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...MK
NEAR TERM...CP
SHORT TERM...MK
LONG TERM....TDUD
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1109 AM EST SUN JAN 13 2013
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 326 AM EST SUN JAN 13 2013
COLD FRONT WILL SLOWLY SETTLE SOUTHEAST OF CENTRAL INDIANA TODAY
RESULTING IN THE END OF PRECIPITATION AFTER MIDNIGHT SUNDAY NIGHT
BUT NOT BEFORE HEAVY RAIN CHANGES OVER TO A WINTRY MIX FROM
NORTHWEST TO SOUTHEAST WITH MINOR ICE OR SNOW ACCUMULATION POSSIBLE.
MUCH COLDER MORE SEASONABLE AIR WILL FILTER IN ALONG WITH DRY
WEATHER THROUGH NEXT WEEKEND. THIS WILL ALLOW RIVER FLOODING TO RUN
ITS COURSE.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1049 AM EST SUN JAN 13 2013
RADAR MOSAIC AND OBSERVATIONS SHOW RAIN STILL FALLING OVER
SOUTHEASTERN FORECAST AREA WITH AREAS OF DRIZZLE OR VERY LIGHT
RAIN OVER THE REST OF THE AREA. AT 11 AM TEMPERATURES RANGED FROM
THE MID 40S IN THE SOUTHEAST TO RIGHT JUST BELOW THE FREEZING MARK
IN THE NORTHWEST. THE COLD FRONT HAS STALLED JUST SOUTH OF THE
AREA AND A SURFACE WAVE IS MOVING ALONG IT INTO THE AREA. THIS
WAVE IS KEEPING THE SUB-FREEZING AIR FROM ADVANCING INTO THE AREA.
FORECAST SOUNDINGS FROM THE RAPID REFRESH AND RAP AS WELL AS THE
NAM SHOW AN INTRUSION OF COLD AIR JUST ABOVE THE SURFACE FROM THE
NORTHWEST WITH A WARM LAYER ABOVE IT AND LOOKS LIKE IT COULD ALLOW
RAIN TO CHANGE OVER OR MIX WITH SLEET IN THE NORTHWEST OVER THE
NEXT COUPLE OF HOURS AND SPREADING SOUTHEAST FROM THERE. SNOW
COULD MIX IN AFTER 1 IN THE NORTHWEST BUT CHANGE OVER TO JUST SNOW
DOESN/T APPEAR LIKELY IN THE NORTHWEST UNTIL AFTER 4 PM. SURFACE
TEMPERATURES HOLDING FAIRLY STEADY OR JUST FALLING SLOWLY OVER THE
NEXT SEVERAL HOURS SO DO NOT SEE A WIDESPREAD RISK FOR FREEZING
RAIN. THE WESTERN COUNTIES WILL SEE THE GREATEST RISK FOR ANY KIND
OF FREEZING RAIN OR FREEZING DRIZZLE BUT STILL DO NOT EXPECT MUCH
IN THE WAY OF ANY ACCUMULATION OF ICE. SOUTHEASTERN COUNTIES CAN
JUST EXPECT RAIN TO INCREASE IN INTENSITY AND COVERAGE THROUGH THE
AFTERNOON AS THE SURFACE WAVE MOVES NORTHEAST ALONG THE FRONT.
WILL CONTINUE WITH THE FLOOD WATCH AS ADDITIONAL HEAVY RAIN COULD
EXACERBATE CURRENT FLOODING SITUATION ACROSS THE AREA...BUT NOT
ANTICIPATING MORE THAN UP TO AN ADDITIONAL HALF INCH IN THE
SOUTHEAST WITH PERHAPS A QUARTER INCH OR LESS NORTH OF I 70.
CHANGE OVER TO SNOW LOOKS FAIRLY LATE...PROBABLY NOT UNTIL THE
TONIGHT PERIOD IN THE CENTRAL AND SOUTH...AND IS FOLLOWED QUICKLY
BY ARRIVAL OF DRY AIR SO DO NOT EXPECT MUCH IN THE WAY OF
ACCUMULATION. COULD SEE LIGHT ACCUMULATIONS OF SLEET IN THE WEST.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 326 AM EST SUN JAN 13 2013
THE SHORT TERM FOCUS WILL BE MAINLY ON TEMPERATURES AS A VERY DRY
COLUMN WILL BE IN PLACE THROUGH THE PERIOD AS PLAINS HIGH PRESSURE
BUILDS IN ACROSS THE OHIO VALLEY AND LOWER GREAT LAKES RESULTING IN
LITTLE CLOUD COVER AND SLIGHTLY BELOW AVERAGE TEMPERATURES.
OVERALL...00Z MOS NUMBERS LOOK OK. THE ONLY CAVEAT IS THE NAM MOS
LOOKS SEVERAL DEGREES TOO WARM AT BMG BASED ON ITS OTHER FORECASTED
NUMBERS AND THE GFS MOS. ALLBLEND IS A GOOD PROXY. LOOK FOR
AFTERNOON HIGHS IN THE UPPER 20S TO THE MID 30S ON MONDAY AND IN THE
30S ON TUESDAY. OVERNIGHT LOWS WILL BE IN THE UPPER TEENS TO THE
LOWER 20S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
ISSUED AT 329 AM EST SUN JAN 13 2013
A DRY EXTENDED PERIOD IS STILL EXPECTED FOR CENTRAL INDIANA
DESPITE A FEW DISTURBANCES IN THE MEAN FLOW ON WEDNESDAY AND
FRIDAY. THE EURO IS NOW IN LINE WITH THE GFS IN REGARD TO SOME
PRECIP ACROSS NORTHERN INDIANA ON WEDNESDAY...BUT LATEST
INITIALIZATION KEEPS THE FORECAST DRY AND THIS LOOKS GOOD SINCE
PRECIP WILL STAY NORTH OF FORECAST AREA. ANOTHER LOW WILL PASS
OVER THE GREAT LAKES REGION AT THE END OF THE WEEK...BUT ALL
PRECIP WILL STAY WELL NORTH OF CENTRAL INDIANA WITH THIS
DISTURBANCE AS WELL. TEMPS WILL BE CLOSE TO NORMAL...BUT A MUCH
MORE FRIGID AIRMASS IS PROGGED FOR THE REGION BEYOND THE LONG
TERM PERIOD.
&&
.AVIATION /DISCUSSION FOR THE 131500Z TAF ISSUANCE/...
ISSUED AT 941 AM EST SUN JAN 13 2013
STEADIEST RAINFALL HAS MOVED EAST OF ALL OF THE TERMINALS AND AS
EXPECTED WITH A POCKET OF SLIGHTLY DRIER AIR ALOFT TRAVERSING THE
REGION...PRECIP HAS LIGHTENED CONSIDERABLY TO DRIZZLE OR VERY LIGHT
RAIN. THIS SHOULD CONTINUE FOR THE NEXT FEW HOURS WITH IFR AND LOWER
CONDITIONS AT ALL TERMINALS. SECONDARY SURFACE WAVE LIFTING THROUGH
THE TENNESSEE VALLEY WILL BRING STEADIER PRECIP BACK INTO THE
FORECAST AREA BY EARLY AFTERNOON. MOST RECENT SHORT RANGE GUIDANCE
INDICATING COLDER AIR MAY BE SLIGHTLY DELAYED IN ITS EXPANSION INTO
THE FORECAST AREA THIS AFTERNOON AND HAVE SLOWED THE CHANGEOVER TO
SLEET AND EVENTUALLY SNOW AT ALL SITES BY AN HOUR OR TWO. KLAF WILL
BE IMPACTED FIRST BY 16-17Z WITH THE OTHER THREE SITES SEEING MIXING
BEGIN BETWEEN 18-21Z FROM WEST TO EAST. CEILINGS WILL REMAIN LOWER
THAN 1000FT INTO THE EVENING.
12Z DISCUSSION FOLLOWS.
POOR FLYING CONDITIONS WILL PERSIST FOR MOST OF TAF PERIOD AS
WIDESPREAD RAINFALL COVERS MOST OF CENTRAL INDIANA. ANTICIPATE IFR
CONDITIONS THROUGH SUN 00Z AND THEN QUICK IMPROVEMENT TO MVFR
CATEGORY THIS EVENING...AND FINALLY VFR AFTER MON 06Z.
CURRENTLY...THE COLD FRONT ASSOCIATED WITH THE PRECIP IS SOUTHEAST
OF ALL TAF SITES. PRECIP HAS ENDED FOR THE MOMENT AT KLAF AND
KHUF...BUT IT SHOULD COMMENCE AGAIN BY LATE MORNING AS ANOTHER
WAVE RIDES ALONG THAT COLD FRONT. MEANWHILE...LIGHT RAIN/DRIZZLE
WILL CONTINUE TO PERSIST AT KIND AND KBMG.
BY THE TIME PRECIP STARTS UP AGAIN...COLDER AIR WILL BE IN PLACE AT
KLAF AND KHUF...AND THE TRANSITION TO WINTRY MIX WILL BEGIN. THE
COLDER AIR WILL WORK ITS WAY INTO KIND AND KBMG BY MID AFTERNOON.
PRECIP WILL TRANSITION FROM FREEZING RAIN/SLEET MIX TO SNOW.
WINDS WILL BE NORTHWESTERLY AT 10 TO 12 KTS WITH GUSTS UP TO 22
KTS AT TIMES.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL 4 PM EST THIS AFTERNOON FOR INZ030-031-036>042-
044>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...MK
NEAR TERM...CP
SHORT TERM...MK
LONG TERM....TDUD
AVIATION...TDUD/RYAN
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1256 PM EST SUN JAN 13 2013
.Forecast Update...
Issued at 1255 PM EST Sun Jan 13 2013
Heavier rains across portions of east central Kentucky and parts of
central Kentucky overnight have resulted in lower flash flood
guidance. With rains ongoing and heavier rains with embedded
thunderstorms moving into the area, have gone ahead and expanded the
Flood Watch east. Small rivers may quickly rise to near flood stage
this afternoon and minor areal flooding will be possible with the
heaviest rain. Updates are already out.
Issued at 940 AM EST Sun Jan 13 2013
The first heavier wave of precipitation has pushed to the east this
morning with mostly light rain across much of the forecast area.
Southwest portions of central Kentucky are most likely seeing some
moderate rain at this time. The highest rainfall report we have
received for the last 24 hours is a bit over 2 inches, though
portions of Dubois county have likely seen higher amounts.
Though the rain has begun to move out of southern Indiana, it looks
to increase again this afternoon. Another wave of rain is moving
across Arkansas. The latest runs of the rapid refresh and HRRR show
this area moving across the northwestern portions of the forecast
area. Additionally, some heavier rain showers look to continue to
move out of central TN into could central Kentucky. All told, much
of the region may see an additional one to possibly two inches of
rain today. Though not much areal flooding has been reported yet, it
will still be possible this afternoon as rains move once again
across saturated grounds.
Have adjusted the forecast based on current trends. In addition,
temperatures behind the front are falling faster than the previous
forecast, so did some adjustments to the hourly temps as well.
Updates are already out.
&&
.Short Term (Today through Monday)...
Issued at 330 AM EST Sun Jan 13 2013
...Flood Watch in Effect through Sunday Evening for areas along and
west of I-65...
Several disturbances ejecting out of strong southwest flow along a
slow-moving baroclinic zone will be the main story this short term
period. Heavy rain, strong winds, and even some wintry
precipitation on the backside all look in play over the next 36
hours.
The synoptic boundary is currently draped from western Ohio
southwest through southern Indiana and western Kentucky. As waves
ride along this boundary, convergence is enhanced and there have
been several rounds of strong, to occasionally severe thunderstorms
as storms accelerate along the mesoscale cold front. Radar has
shown a weakening trend over the last hour or so, and expect that to
be the general rule through early this morning. However, with 40-50
knots just off the surface, the stronger showers and isolated
thunderstorms will be able to pull down higher momentum air,
resulting in gusts up to 50 MPH.
The strong thunderstorm threat should continue to wane through the
morning hours as storms outrun the better instability. Then the
attention turns to the heavy rain potential. The 13/00Z NAM has a
pretty good handle on current trends, albeit a bit slow with the
precipitation. Thus, have leaned on it for the short term forecast,
but bringing things in a bit quicker. PWATs have risen to near 1.5
inches overnight (00Z OHX sounding came in with 1.29) and warm cloud
depths will remain at 10-12 thousand feet today. Copious moisture
transport on the nose of a low-level jet will feed into the
slow-moving boundary, producing moderate to locally heavy rainfall.
In addition, latest guidance continues to advertise another synoptic
shortwave lifting northeast along the boundary late this morning
into early this afternoon. This will help enhance precipitation
rates, especially across south central Kentucky generally west of
I-65. Think that 2 to 3 inches is possible there, with locally
higher amounts. Elsewhere, generally 1-2 inches is likely as the
front slowly progresses east.
In addition to the heavy rain potential, another added element to
this system is the chance for wintry precipitation as the front
exits. However, latest guidance continues to speed up the
progression of the precipitation, seemingly outrunning the colder
air. However, model soundings do still hint at some "freezing" rain
potential on the backside. I say "freezing", due to the fact that
the ground will be rather wet and warm still, so although surface
temperatures will slide below freezing, no ice accumulation is
expected beside maybe a real light glaze on elevated surfaces.
Otherwise, the system slides to the far southeastern CWA on Sunday
night, ending all precipitation. With many surfaces still remaining
wet, there is a chance of some isolated black ice as temperatures
quickly fall Sunday night into Monday morning. Will have to monitor
this potential closely in the coming 24 hours.
Temperatures will continue to remain very mild this morning ahead of
the cold front, before crashing later in the day as the front sweeps
through. Lows will drop into the low 20s in southern Indiana and
the low 30s across southern KY. Highs on Monday will only climb
into the 30s and lower 40s.
.Long Term (Monday Night - Saturday)...
Issued at 320 AM EST Sun Jan 13 2013
Did not spend time diagnosing the models this forecast cycle because
of returns on 88D. Have blended with the previous forecast with the
new set of model consensus. The product is a forecast that has lows
near normal each day and highs not straying too far from normal
either. Rain chances are limited to the south and east forecast area
Monday night through Tuesday night. Model soundings indicate
temperatures close to freezing for most of the lower levels of the
atmosphere, so cannot rule out either rain or snow, should model
surface and low-level temperatures be off, so will continue to
advertise generally a rain/snow mix. Otherwise, from Wednesday on,
this forecast package will be dry.
&&
.Aviation (18Z TAF Issuance)...
Issued at 1205 PM EST Sun Jan 13 2013
The cold front that will be moving through the area has stalled out
for a bit this morning just to the northwest of SDF. This has
delayed the wind shift and the lower cigs from moving into the
region. Ceilings are still expected to drop to 1 kft or just below
over the next couple of hours at SDF and BWG. In addition, at BWG
some thunderstorms have developed in the area so will carry VCTS
there for a couple of hours.
The main challenge will be the wind shift and ceilings through this
TAF period. The lower ceilings will move out late this evening or
overnight as the cold front moves off to the southeast. Mid and high
clouds will likely hang around overnight and into tomorrow morning.
As the front passes through winds will shift to the northwest and
then to northerly through tomorrow morning.
&&
.Hydrology...
Unseasonably warm, moist air continues to be pooled into the Ohio
Valley. Decent amounts of rain continue to fall ahead of and along
an approaching cold front as the atmosphere is laden with moisture.
Precipitable water values are unseasonably high for this time of
year. Numerous rain showers are expected to continue throughout the
day. Additional rain amounts today look to be in the 1 to 2 inch
range. QPF totals are anticipated to be from about 1.5 to 4 inches
with locally higher amounts will be possible.
What this all translates to is the possibility for some minor areal
(see the issued Flood Watch for more details) and river flooding to
occur along prone banks. The location to watch initially looks to be
Dundee on the Rough River in the Green River basin which may reach
flood stage tonight. Additional spots to watch over the next 24 to
36 hours include locations along the Green and Salt River basins as
well as small creeks and streams. This includes Rochester, Alvaton
(Drakes Creek), Woodbury, and Boston (Rolling Fork River). As the
precipitation moves off toward the north and east, additional basins
will be under close observation as the rain flows downstream.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...FLOOD WATCH UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
INZ076>079-083-084-089>092.
KY...FLOOD WATCH UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
KYZ023>042-045>048-053>055-061>065-070>077-081.
$$
Update...........EER
Short Term.......KD
Long Term........RJS
Aviation.........EER
Hydrology........LG/AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1206 PM EST SUN JAN 13 2013
...Updated Aviation Discussion...
.Forecast Update...
Issued at 940 AM EST Sun Jan 13 2013
The first heavier wave of precipitation has pushed to the east this
morning with mostly light rain across much of the forecast area.
Southwest portions of central Kentucky are most likely seeing some
moderate rain at this time. The highest rainfall report we have
received for the last 24 hours is a bit over 2 inches, though
portions of Dubois county have likely seen higher amounts.
Though the rain has begun to move out of southern Indiana, it looks
to increase again this afternoon. Another wave of rain is moving
across Arkansas. The latest runs of the rapid refresh and HRRR show
this area moving across the northwestern portions of the forecast
area. Additionally, some heavier rain showers look to continue to
move out of central TN into could central Kentucky. All told, much
of the region may see an additional one to possibly two inches of
rain today. Though not much areal flooding has been reported yet, it
will still be possible this afternoon as rains move once again
across saturated grounds.
Have adjusted the forecast based on current trends. In addition,
temperatures behind the front are falling faster than the previous
forecast, so did some adjustments to the hourly temps as well.
Updates are already out.
&&
.Short Term (Today through Monday)...
Issued at 330 AM EST Sun Jan 13 2013
...Flood Watch in Effect through Sunday Evening for areas along and
west of I-65...
Several disturbances ejecting out of strong southwest flow along a
slow-moving baroclinic zone will be the main story this short term
period. Heavy rain, strong winds, and even some wintry
precipitation on the backside all look in play over the next 36
hours.
The synoptic boundary is currently draped from western Ohio
southwest through southern Indiana and western Kentucky. As waves
ride along this boundary, convergence is enhanced and there have
been several rounds of strong, to occasionally severe thunderstorms
as storms accelerate along the mesoscale cold front. Radar has
shown a weakening trend over the last hour or so, and expect that to
be the general rule through early this morning. However, with 40-50
knots just off the surface, the stronger showers and isolated
thunderstorms will be able to pull down higher momentum air,
resulting in gusts up to 50 MPH.
The strong thunderstorm threat should continue to wane through the
morning hours as storms outrun the better instability. Then the
attention turns to the heavy rain potential. The 13/00Z NAM has a
pretty good handle on current trends, albeit a bit slow with the
precipitation. Thus, have leaned on it for the short term forecast,
but bringing things in a bit quicker. PWATs have risen to near 1.5
inches overnight (00Z OHX sounding came in with 1.29) and warm cloud
depths will remain at 10-12 thousand feet today. Copious moisture
transport on the nose of a low-level jet will feed into the
slow-moving boundary, producing moderate to locally heavy rainfall.
In addition, latest guidance continues to advertise another synoptic
shortwave lifting northeast along the boundary late this morning
into early this afternoon. This will help enhance precipitation
rates, especially across south central Kentucky generally west of
I-65. Think that 2 to 3 inches is possible there, with locally
higher amounts. Elsewhere, generally 1-2 inches is likely as the
front slowly progresses east.
In addition to the heavy rain potential, another added element to
this system is the chance for wintry precipitation as the front
exits. However, latest guidance continues to speed up the
progression of the precipitation, seemingly outrunning the colder
air. However, model soundings do still hint at some "freezing" rain
potential on the backside. I say "freezing", due to the fact that
the ground will be rather wet and warm still, so although surface
temperatures will slide below freezing, no ice accumulation is
expected beside maybe a real light glaze on elevated surfaces.
Otherwise, the system slides to the far southeastern CWA on Sunday
night, ending all precipitation. With many surfaces still remaining
wet, there is a chance of some isolated black ice as temperatures
quickly fall Sunday night into Monday morning. Will have to monitor
this potential closely in the coming 24 hours.
Temperatures will continue to remain very mild this morning ahead of
the cold front, before crashing later in the day as the front sweeps
through. Lows will drop into the low 20s in southern Indiana and
the low 30s across southern KY. Highs on Monday will only climb
into the 30s and lower 40s.
.Long Term (Monday Night - Saturday)...
Issued at 320 AM EST Sun Jan 13 2013
Did not spend time diagnosing the models this forecast cycle because
of returns on 88D. Have blended with the previous forecast with the
new set of model consensus. The product is a forecast that has lows
near normal each day and highs not straying too far from normal
either. Rain chances are limited to the south and east forecast area
Monday night through Tuesday night. Model soundings indicate
temperatures close to freezing for most of the lower levels of the
atmosphere, so cannot rule out either rain or snow, should model
surface and low-level temperatures be off, so will continue to
advertise generally a rain/snow mix. Otherwise, from Wednesday on,
this forecast package will be dry.
&&
.Aviation (18Z TAF Issuance)...
Issued at 1205 PM EST Sun Jan 13 2013
The cold front that will be moving through the area has stalled out
for a bit this morning just to the northwest of SDF. This has
delayed the wind shift and the lower cigs from moving into the
region. Ceilings are still expected to drop to 1 kft or just below
over the next couple of hours at SDF and BWG. In addition, at BWG
some thunderstorms have developed in the area so will carry VCTS
there for a couple of hours.
The main challenge will be the wind shift and ceilings through this
TAF period. The lower ceilings will move out late this evening or
overnight as the cold front moves off to the southeast. Mid and high
clouds will likely hang around overnight and into tomorrow morning.
As the front passes through winds will shift to the northwest and
then to northerly through tomorrow morning.
&&
.Hydrology...
Unseasonably warm, moist air continues to be pooled into the Ohio
Valley. Decent amounts of rain continue to fall ahead of and along
an approaching cold front as the atmosphere is laden with moisture.
Precipitable water values are unseasonably high for this time of
year. Numerous rain showers are expected to continue throughout the
day. Additional rain amounts today look to be in the 1 to 2 inch
range. QPF totals are anticipated to be from about 1.5 to 4 inches
with locally higher amounts will be possible.
What this all translates to is the possibility for some minor areal
(see the issued Flood Watch for more details) and river flooding to
occur along prone banks. The location to watch initially looks to be
Dundee on the Rough River in the Green River basin which may reach
flood stage tonight. Additional spots to watch over the next 24 to
36 hours include locations along the Green and Salt River basins as
well as small creeks and streams. This includes Rochester, Alvaton
(Drakes Creek), Woodbury, and Boston (Rolling Fork River). As the
precipitation moves off toward the north and east, additional basins
will be under close observation as the rain flows downstream.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...FLOOD WATCH UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
INZ076>079-083-084-089>092.
KY...FLOOD WATCH UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
KYZ023>030-053-061>063-070>075.
$$
Update...........EER
Short Term.......KD
Long Term........RJS
Aviation.........EER
Hydrology........LG/AMS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
101 PM EST SUN JAN 13 2013
.UPDATE...
ISSUED AT 1128 AM EST SUN JAN 13 2013
CONTINUE TO FINE TUNE THE FORECAST FOR THE DOMINANT LES BAND THAT IS
PARALLELING THE W UPPER MI SHORELINE. VIS IN THIS BAND HAS BEEN ABLE
TO FALL TO 3/4SM AT CMX AS IT GLANCED THE AIRPORT. OUR ABILITY TO
LOCATE THIS BAND MAY BE DIMINISHING OVER THE NEXT FEW HOURS IF THE
MID CLOUDS OVER N WI CONTINUE TO SLOWLY FILTER N ACROSS LAKE
SUPERIOR. WILL CONTINUE TO KEEP MUCH OF THE MORE SIGNIFICANT SNOW
OUT OF IWD UNTIL MID TO LATE AFTERNOON...AS DEPICTED BY SOME OF THE
MORE SMALL SCALE MODEL TRENDS...GIVEN THE SLIGHT W TICK OF THE WINDS
AT THE LOWEST LEVELS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 533 AM EST SUN JAN 13 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
CENTRAL CANADA THROUGH THE WRN PLAINS AND A RIDGE OFF THE EAST COAST
RESULTING IN SW FLOW FROM THE SRN PLAINS INTO THE GREAT LAKES. AN
UPSTREAM SHORTWAVE TROUGH WAS LOCATED OVER NEBRASKA. AT THE
SFC...THE MAIN TROUGH/FRONT AND FOCUS FOR HEAVIER PCPN WAS LOCATED WELL
TO THE SOUTH...FROM NW OH THROUGH WRN KY INTO NRN MS. TO THE
WEST...AN ARCTIC HIGH PRES RIDGE EXTENDED FROM ALBERTA/SASK INTO THE
WRN PLAINS. WITH MAINLY NW LOW LEVEL FLOW ACROSS THE NRN LAKES...LAKE
INDUCED TROUGHING HAS KEPT LOW LEVEL CONV FOCUSED NEAR THE LAKE FROM
IWD-P59. EVEN THOUGH 850 MB TEMPS TO AROUND -20C OVER WRN LAKE
SUPERIOR PROVIDED PLENTY OF INSTABILITY(LAKE INDUCED CAPE VALUES TO
AROUND 400 J/KG) LOW INVERSION HEIGHTS AROUND 4K FT WITH PROMINENT
MID LEVEL DRYING HAS LIMITED LES RATES WITH ONLY LIGHT ACCUMULATIONS
OF A FEW INCHES OVERNIGHT. THE DRY AIR...SLIGHTLY LOWER INVERSION
HEIGHTS AND 850 MB TEMPS ONLY NEAR -12C...HAS INHIBITED LES OVER THE
ERN LAKE.
MAIN FCST CONCERNS ARE LES TRENDS.
MODELS WERE CONSISTENT IN BRINGING THE NEBRASKA SHRTWV NORTHEAST
THROUGH THE WRN GREAT LAKES. EVEN WITH MODERATE TO STRONG 700-300 MB
QVECTOR CONV AHEAD OF THE SHRTWV...LITTLE SYNOPTIC PCPN IS EXPECTED
IN THE DRY AIRMASS TO THE NORTH OF THE MAIN FRONTAL BOUNDARY. SOME
LIGHT SNOW WILL BE POSSIBLE WITH THIS FEATURE WITH ANY ACCUMULATIONS
AMOUNTING TO TO A HALF INCH OR LESS.
THE MAIN IMPACT WILL BE TO INVIGORATE THE LES...ESPECIALLY LATE THIS
AFTERNOON AND EVENING...AS DEEPER MOISTURE MOVES IN AND INVERSION
HEIGHTS CLIMB AOA 7K FT WITH 850 MB TEMPS AROUND -19C. WITH THE DGZ IN
THE CONVECTIVE LAYER...SNOW/WATER RATIO VALUES SHOULD ALSO REMAIN
HIGH(FROM 25/1 TO 30/1). VEERING WINDS WILL SHIFT THE FOCUS OF THE
HEAVIER LES TO AREAS BTWN HOUGHTON AND THE PORCUPIN MOUNTAINS AND
ALSO WILL ALLOW THE LES TO PUSH INTO THE EAST (LOCATIONS FROM AU
TRAIN EASTWARD).
ONGOING ADVISORIES AND SNOWFALL AMOUNTS LOOK ON TRACK WITH 12 HOUR
AMOUNTS OF 1 TO 4 INCHES WEST TODAY AND 2 TO 5 INCHES TONIGHT. OVER
THE EAST...1 TO 3 INCHES ARE EXPECTED THIS AFTERNOON WITH AMOUNTS OF
3 TO 6 INCHES POSSIBLE...GREATEST NEAR THE LAKE EAST OF MUNISING.
SOME HIGHER AMOUNTS MAY BE POSSIBLE EAST IF A MORE DOMINANT BAND
DEVELOPS BUT CONFIDENCE IN THE LOCATION IS LIMITED GIVEN SIGNFICNAT
DIFFERENCES BETWEEN THE HIGHER RES MODELS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 426 AM EST SUN JAN 13 2013
WEST TO NORTHWEST FLOW LAKE EFFECT WILL BE ONGOING AT THE START OF
THE LONG TERM PERIOD. BUT WITH THE SURFACE TROUGH OVER EASTERN LAKE
SUPERIOR DIMINISHING DURING THE MORNING DUE TO A HIGH PRESSURE
RIDGE MOVING THROUGH MN...EXPECT THE WINDS TO BACK THROUGH THE DAY
AND BE OUT OF THE WEST-SOUTHWEST BY 00Z TUESDAY. THIS WILL PUSH THE
LAKE EFFECT OFFSHORE OVER THE EAST BY EARLY AFTERNOON AND FOCUS THE
LAKE EFFECT OVER THE KEWEENAW PENINSULA OVER THE WEST. SINCE
INVERSION HEIGHTS ARE STILL IN THE 7-8KFT RANGE AND DELTA-T VALUES
ARE AROUND 22...CONDITIONS ARE FAVORABLE FOR MODERATE SNOW TO
CONTINUE ON MONDAY. WITH THE SOUTHERN EDGE OF THE LAKE EFFECT BAND
BEING AIDED BY ENHANCED CONVERGENCE FROM THE BACKING WINDS...THINK
THERE SHOULD BE AT LEAST ONE STRONGER BAND GRADUALLY DRIFTING NORTH
THROUGH NORTHERN HOUGHTON COUNTY DURING THE DAY. THE BIGGEST
CONCERN WILL BE THE NORTHWARD PUSH IN THE MORNING...WHICH THEN
STALLS IN THE AFTERNOON AS WHAT IS LEFT OF THE SURFACE TROUGH
STALLS OVER THE KEWEENAW. WHERE THIS BAND STALLS OR DOESN/T
STALL WILL DETERMINE SNOWFALL AMOUNTS. BUFKIT SOUNDINGS SHOWING
FAVORABLE CONDITIONS FOR VERY FLUFFY 30-1 SNOW RATIOS...AS THE BEST
OMEGA IS CENTERED RIGHT IN THE DGZ...MUCH OF THE CLOUD IS IN THE
DGZ...AND WIND SPEEDS ARE NOT OVERLY STRONG. WILL FOLLOW THAT IDEA
FOR THE FORECAST AND BUMP RATIOS TOWARDS THAT. WITH THE WAY MODELS
ARE LOOKING...COULD BE A PERIOD OF EVEN HEAVY SNOW DURING THE LATE
MORNING AND AFTERNOON HOURS...SINCE POCKET OF DEEPER H850-700
MOISTURE HELPS PUSH LAKE EFFECT SNOW PARAMETER VALUES WELL OVER 2.
HAVE FINE TUNED THE POPS DURING THIS PERIOD AND BUMPED SNOWFALL
AMOUNTS UP A FEW INCHES. 00Z RUNS OF BOTH THE NESTED 4KM NAM AND OUR
LOCAL WRF-ARW COBB SNOWFALL OUTPUT ARE INDICATING 10IN OF SNOW FOR
KCMX FROM 12Z MONDAY THROUGH 06Z TUESDAY. HAD SOME CONCERN EXTENDING
THE ADVISORY FOR ANOTHER 12HRS SINCE IT WAS A SIGNIFICANT JUMP FROM
PREVIOUS RUNS...BUT WITH GOING FORECAST VALUES OF 3-5 INCHES ON
MONDAY COULDN/T HOLD OFF ON IT.
WITH THE HIGH PRESSURE RIDGE SLIDING EAST ACROSS WISCONSIN ON
MONDAY NIGHT...INDICATIONS ARE THE WINDS BACKING MORE TO THE
SOUTHWEST. THIS WILL PUSH THE STRONGER SNOW TO THE NORTH THROUGH
KEWEENAW COUNTY AND BRING AN END TO THE LES FOR THE CWA FOR
A DAY OR TWO DUE TO H850 TEMPS WARMING TO -10C UNDER THE STRONG
SOUTHWESTERLY FLOW ON TUESDAY.
THIS INCREASING SOUTHWESTERLY FLOW IS IN RESPONSE TO AN APPROACHING
SHORTWAVE AND CLIPPER SYSTEM DROPPING THROUGH THE NORTHWEST FLOW
ALOFT. THIS COULD PRODUCE SOME BREEZY CONDITIONS ON TUESDAY
INTO TUESDAY NIGHT. BOTH NAM/GFS SHOWING H925 WINDS OF
40-50KTS...BUT A WEAK INVERSION MAY BE ENOUGH TO KEEP THAT
FROM REACHING THE SURFACE OVER LAND. OVER LAKE SUPERIOR...BUFKIT
SOUNDINGS SHOWING MUCH OF THAT REACHING THE SURFACE DUE TO STRONG
PRESSURE FALL /14MB IN 12HR/ MOVING ACROSS THE LAKE. THUS...HAVE
BUMPED WINDS UP A SOLID 10KTS TO GALES AND IF LATEST TRENDS ARE
CORRECT THEY WILL NEED TO GO ANOTHER 5-10KTS HIGHER. DEFINITELY
SEEING BETTER AGREEMENT IN THE MODELS WITH THE TIMING/TRACK OF THE
SYSTEM...ALTHOUGH THE ECMWF/GEM ARE A LITTLE FARTHER SOUTH AND
SLOWER WITH AN ELONGATED SURFACE TROUGH AS IT MOVES THROUGH LATE
TUESDAY NIGHT INTO WEDNESDAY. EITHER SOLUTION SHOULD LEAD TO AT
LEAST A DUSTING TO AN INCH OF SNOW CWA WIDE...BUT ECMWF/GEM COULD
PRODUCE SOME AREAS WITH A COUPLE INCHES OF SNOW.
COLD AIR WILL SURGE IN BEHIND THIS CLIPPER...AS THE POLAR VORTEX
DIVES SOUTHEAST TOWARDS JAMES BAY. AT THIS POINT IT LOOKS TO STAY
THERE...BUT IT WILL STILL LEAD TO H850 TEMPS IN THE LOW TO MID -20S.
WITH HIGH PRESSURE CENTERED IN THE CENTRAL PLAINS AND A LOW OVER
HUDSON BAY...EXPECT NORTHWESTERLY WINDS AT THE SURFACE AND THROUGH
H850. THIS WILL LEAD TO PERSISTENT LES IN THAT FAVORED WIND
DIRECTION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. WILL CONTINUE TO
HIGHLIGHT HIGH END LIKELY POPS IN THAT AREA. INTENSITY WILL DEPEND
ON THE INVERSION HEIGHTS AND IF ANY DEEPER MOISTURE OR SHORTWAVES
SWEEP THROUGH. 00Z GFS SHOWING LAKE INDUCED EQL HEIGHTS OF
7-9KFT...BUT MOISTURE REMAINS BELOW 5KFT WITH FORCING ON HIGHER
EDGE OF DGZ. THUS...POTENTIAL IS THERE FOR MODERATE SNOW...BUT
MOISTURE WILL BE CONTROLLING FACTOR.
GFS/ECMWF CONTINUING TO SHOW THE POTENTIAL FOR A WEAK SHORTWAVE
SLIDING THROUGH THE NORTHWEST FLOW ON FRIDAY AND AGAIN ON SATURDAY.
THIS LEADS TO SOME UNCERTAINTY IN THE LAKE EFFECT LOCATIONS AND
JUST LOW END CHANCE OR SLIGHT POPS ACROSS THE REST OF THE CWA.
AFTER A BELOW NORMAL START TO THE WORK WEEK...TEMPERATURES LOOK TO
RETURN TO NORMAL FOR TUESDAY/WEDNESDAY BEFORE FALLING 5-10 DEGREES
BELOW NORMAL FOR THE END OF THE WORK WEEK. FINALLY...00Z GFS HAS
TRENDED TOWARDS WHAT THE ECMWF HAS BEEN SHOWING WITH THE POLAR
VORTEX DIVING SOUTH INTO THE GREAT LAKES ON SUNDAY/MONDAY.
SIGNIFICANT DIFFERENCES IN THE AMOUNT OF COLD AIR BETWEEN THE
MODELS...SO IT WILL BE INTERESTING TO SEE WHICH ONE PANS OUT. IF
ECMWF IS RIGHT...H850 TEMPS WILL BE AROUND -35C AND WOULD LEAD TO
INLAND AREAS ON SLIGHTLY ABOVE ZERO FOR HIGHS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 100 PM EST SUN JAN 13 2013
THE DOMINANT LAKE EFFECT SNOW BAND OVER WESTERN LAKE SUPERIOR IS
SLOWLY PUSHING FARTHER ONSHORE. WHILE IT IS BRINGING VIS TEMP DOWN
TO 1SM AT CMX...THE MORE DOWNSLOPE SW WIND DIRECTION AT IWD IS
POSTPONING THE ONSHORE MOVEMENT OF THE S PORTION OF THE BAND. STILL
ANOTHER SWATH OF MVFR CEILINGS HAS BEEN STEADILY SHIFTING N FROM W
WI...WITH MORE ONSHORE FLOW AT IWD TOWARD SUNSET. GIVEN THE LESS
FAVORABLE WIND DIRECTION AT SAW THROUGH THE ENTIRE PERIOD...ONLY
MVFR TO VFR CEILINGS/VIS ARE EXPECTED THROUGH 18Z MONDAY. MORE W-SW
WINDS WILL BRING DRIER AIR TO BOTH IWD AND SAW DURING THE DAY
MONDAY...WHILE LAKE EFFECT SNOW SHOWERS CONTINUE OFF AND ON AT CMX
THROUGH AT LEAST EARLY AFTERNOON.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 533 AM EST SUN JAN 13 2013
NORTHWEST WINDS ARE EXPECTED TO REMAIN AT OR BELOW 25 KNOTS THROUGH
MONDAY AS HIGH PRESSURE GRADUALLY BUILDS FROM THE PLAINS TOWARD THE
GREAT LAKES. A CLIPPER LOW PRES SYSTEM MOVING INTO SRN MANITOBA
TUESDAY AND NORTHERN ONTARIO TUE NIGHT WILL LIKELY BRING SW GALES
ACROSS LAKE SUPERIOR. AS THE LOW DEEPENS AND MOVES TOWARD NRN QUEBEC
WED...SOME NW GALES MAY ALSO BE POSSIBLE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ006-007.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KF
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...KF
MARINE...JLB
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1243 PM EST SUN JAN 13 2013
.SYNOPSIS...
ISSUED AT 325 AM EST SUN JAN 13 2013
A MIX OF PRECIPITATION INCLUDING SOME FREEZING RAIN THIS MORNING
WILL TRANSITION TO LIGHT SNOW SHOWERS THIS AFTERNOON. LIGHT SNOW
SHOWERS WILL CONTINUE TONIGHT INTO MONDAY. FAIRLY CLOSE TO NORMAL
TEMPERATURES ARE EXPECTED MOST OF THE UPCOMING WEEK WITH OCCASIONAL
LIGHT SNOW SHOWERS AND FLURRIES FROM TIME TO TIME.
&&
.UPDATE...
ISSUED AT 915 AM EST SUN JAN 13 2013
I UPDATED SINCE THERE IS MORE DRIZZLE THEN WAS CURRENTLY IN THE
FORECAST AND ALSO SINCE ALL OF THE MODELS I JUST LOOKED AT
(HRRR...RAP...NAM12...GFS AND ECMWF) ALL SHOW THE NEXT WAVE BRINGING
MEASURABLE PRECIPITATION TO NEARLY ALL OF THE CWA LATE THIS
AFTERNOON INTO THIS EVENING. SATELLITE LOOPS SHOW THE WAVE IS REAL
AND RADAR LOOPS ALSO SHOW THE WAVE NEEDING NORTHEAST FORM AR AND
MO HEADING THIS WAY TOO.
CURRENTLY THERE IS A DRY LAYER BETWEEN 10000 FT AND 20000 FT AS
SEEN ON RAP MODEL SOUNDINGS THAT IS NOT ALLOWING THE DGZ TO BE
SATURATED SO DRIZZLE/LIGHT RAIN IS FALLING INSTEAD OF SNOW OVER
OUR WESTERN CWA. BY EARLY TO MID AFTERNOON THE DEEPER MOISTURE
FROM THE NEXT SHORTWAVE COMES BACK IN SO THEN THE PRECIPITATION
SHOULD LARGELY BE SNOW FROM GRR NORTH AND WEST AND TRANSITION FROM
MIXED PRECIPITATION TO SNOW SOUTH AND EAST OF GRR (BY EVENING). I
DO NOT EXPECT MUCH SNOW OUT OF THIS... MOSTLY AN INCH OR LESS.
THIS MAY NEED UPDATING THROUGH.
UPDATE ISSUED AT 702 AM EST SUN JAN 13 2013
WILL BE CAN CELLING THE WINTER WEATHER ADVISORY AS BOTH RADAR AND
HRRR MODEL GUIDANCE INDICATE WE SHOULD BE PRECIPITATION FREE FOR
THE NEXT SEVERAL HOURS. ROAD WEATHER SENSORS AT CADILLAC/REED
CITY/LUDINGTON SHOW SURFACE TEMPERATURES STILL AROUND 33-35F EVEN
THOUGH AIR TEMPERATURES HAVE GENERALLY FALLEN BELOW FREEZING. ALL
OF THIS SUGGESTS THAT THERE SHOULD BE LITTLE EFFECT ON TRAVEL
CONDITIONS THE REST OF THIS MORNING. UPDATED FORECASTS WILL BE
COMING OUT SHORTLY.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY AFTERNOON)
ISSUED AT 325 AM EST SUN JAN 13 2013
OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO EVALUATE POTENTIAL FOR
FZRA THIS MORNING.
KGRR/RGNL RADAR TRENDS SHOW A LARGE AREA OF LGT TO MDT PCPN OVER OUR
AREA WITH RAIN NEAR TO SOUTH OF I-96 AND SOME MIXED PCPN BEING
REPORTED OVER OUR NORTHERN COUNTIES. SFC OBS AND LOCAL STORM REPORTS
INDICATE FAIRLY EXTENSIVE LIGHT TO MODERATE FZRA UPSTREAM ACROSS
PORTIONS OF WI/IL. PCPN WILL TRANSITION TO A PERIOD OF FZRA THIS
MORNING AS SFC TEMPS CONTINUE TO FALL SLOWLY TO FREEZING.
OUR GOING WINTER WX ADVISORY HEADLINE WILL REMAIN UNCHANGED WITH
HAZARDOUS TRAVEL CONDITIONS LIKELY TO DEVELOP A LITTLE LATER THIS
MORNING (TOWARD DAYBREAK THROUGH LATE MORNING) GIVEN THE MIXED
PCPN/FZRA AND SLOWLY FALLING SFC TEMPS IN NORTHERLY FLOW CAA.
PCPN WILL TRANSITION TO LIGHT SNOW SHOWERS THIS AFTN. LIGHT SNOW
SHOWERS WILL CONTINUE TONIGHT AND MONDAY BUT WITH VERY LIGHT
ACCUMULATIONS OF GENERALLY ONLY AROUND AN INCH OR LESS. MOST OF THAT
WILL COME THIS AFTERNOON AND TONIGHT WITH ONLY VERY LIGHT SNOW
SHOWERS AND FLURRIES EXPECTED TO LINGER MONDAY.
A FEW FLURRIES MAY LINGER INTO MONDAY NIGHT BUT MAINLY DRY
CONDITIONS ARE EXPECTED FOR THIS TIME FRAME WITH A SFC RIDGE IN
PLACE OVER THE LOWER GREAT LAKES REGION.
.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 325 AM EST SUN JAN 13 2013
MAIN CHANGE WAS TO INCREASE CHANCES FOR SNOW WEDNESDAY NIGHT AND
THURSDAY. LAST COUPLE RUNS OF THE PREFERRED ECMWF MODEL ADVERTISE A
MODERATELY STRONG CLIPPER AND ASSOCIATED COLD FRONT PASSING THROUGH
WEDNESDAY NIGHT. LAKE ENHANCED SNOW BEHIND THE CLIPPER LOOKS A BIT
MORE FAVORABLE EARLY THURSDAY WITH BETTER SATURATION IN THE DGZ AND
A BRIEF PERIOD OF COLD ADVECTION /850 MB TEMPERATURES DROPPING TO
AROUND -20C/.
OTHERWISE...NO OTHER SIGNIFICANT CHANGES WERE MADE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1744 PM EST SUN JAN 13 2013
WIDESPREAD IFR CONDITONS WILL PERSIST THIS AFTERNOON AND TONIGHT.
ANOTHER WAVE OF LOW PRESSURE IS MOVING NEWD ALONG THE COLD FRONT
AND WILL PRODUCE A PERIOD OF LIGHT SNOW. THE ERN TAF SITES WILL
SEE THE LONGEST PERIOD OF LIGHT SNOW AND KMKG WILL NOT SEE MUCH AT
ALL UNTIL THE OVERNIGHT HOURS WHEN SOME LIGHT LAKE EFFECT SNOW
SHOWERS WILL DEVELOP. AFTER 06Z CONDITIONS WILL BEGIN TO IMPROVE
WITH HIGHER CIGS/VSBYS. HOWEVER CLOSER TO THE LAKE SHORE SHSN WILL
DEVELOP WITH MVFR VSBYS EXPECTED.
&&
.MARINE...
ISSUED AT 325 AM EST SUN JAN 13 2013
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH MONDAY AS WAVE
HEIGHTS STAY UP TODAY WITH NORTHWEST TO NORTH WINDS AND COLDER AIR
MOVING IN. BRISK WEST WINDS WILL KEEP WAVE HEIGHTS UP TONIGHT INTO
MONDAY.
&&
.HYDROLOGY...
ISSUED AT 325 AM EST SUN JAN 13 2013
MODEST RIVER LEVEL RISES ARE ANTICIPATED IN RESPONSE TO THE RAINFALL
OVERNIGHT BUT NO SIGNIFICANT HYDRO ISSUES ARE EXPECTED SINCE
SIGNIFICANT PRECIPITATION WILL MOVE OUT LATER TODAY AND WITH THE
SIGNIFICANT COOLING TREND OF TEMPS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 3 PM EST MONDAY FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...93
AVIATION...93
HYDROLOGY...LAURENS
MARINE...LAURENS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1128 AM EST SUN JAN 13 2013
.UPDATE...
ISSUED AT 1128 AM EST SUN JAN 13 2013
CONTINUE TO FINE TUNE THE FORECAST FOR THE DOMINANT LES BAND THAT IS
PARALLELING THE W UPPER MI SHORELINE. VIS IN THIS BAND HAS BEEN ABLE
TO FALL TO 3/4SM AT CMX AS IT GLANCED THE AIRPORT. OUR ABILITY TO
LOCATE THIS BAND MAY BE DIMINISHING OVER THE NEXT FEW HOURS IF THE
MID CLOUDS OVER N WI CONTINUE TO SLOWLY FILTER N ACROSS LAKE
SUPERIOR. WILL CONTINUE TO KEEP MUCH OF THE MORE SIGNIFICANT SNOW
OUT OF IWD UNTIL MID TO LATE AFTERNOON...AS DEPICTED BY SOME OF THE
MORE SMALL SCALE MODEL TRENDS...GIVEN THE SLIGHT W TICK OF THE WINDS
AT THE LOWEST LEVELS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 533 AM EST SUN JAN 13 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
CENTRAL CANADA THROUGH THE WRN PLAINS AND A RIDGE OFF THE EAST COAST
RESULTING IN SW FLOW FROM THE SRN PLAINS INTO THE GREAT LAKES. AN
UPSTREAM SHORTWAVE TROUGH WAS LOCATED OVER NEBRASKA. AT THE
SFC...THE MAIN TROUGH/FRONT AND FOCUS FOR HEAVIER PCPN WAS LOCATED WELL
TO THE SOUTH...FROM NW OH THROUGH WRN KY INTO NRN MS. TO THE
WEST...AN ARCTIC HIGH PRES RIDGE EXTENDED FROM ALBERTA/SASK INTO THE
WRN PLAINS. WITH MAINLY NW LOW LEVEL FLOW ACROSS THE NRN LAKES...LAKE
INDUCED TROUGHING HAS KEPT LOW LEVEL CONV FOCUSED NEAR THE LAKE FROM
IWD-P59. EVEN THOUGH 850 MB TEMPS TO AROUND -20C OVER WRN LAKE
SUPERIOR PROVIDED PLENTY OF INSTABILITY(LAKE INDUCED CAPE VALUES TO
AROUND 400 J/KG) LOW INVERSION HEIGHTS AROUND 4K FT WITH PROMINENT
MID LEVEL DRYING HAS LIMITED LES RATES WITH ONLY LIGHT ACCUMULATIONS
OF A FEW INCHES OVERNIGHT. THE DRY AIR...SLIGHTLY LOWER INVERSION
HEIGHTS AND 850 MB TEMPS ONLY NEAR -12C...HAS INHIBITED LES OVER THE
ERN LAKE.
MAIN FCST CONCERNS ARE LES TRENDS.
MODELS WERE CONSISTENT IN BRINGING THE NEBRASKA SHRTWV NORTHEAST
THROUGH THE WRN GREAT LAKES. EVEN WITH MODERATE TO STRONG 700-300 MB
QVECTOR CONV AHEAD OF THE SHRTWV...LITTLE SYNOPTIC PCPN IS EXPECTED
IN THE DRY AIRMASS TO THE NORTH OF THE MAIN FRONTAL BOUNDARY. SOME
LIGHT SNOW WILL BE POSSIBLE WITH THIS FEATURE WITH ANY ACCUMULATIONS
AMOUNTING TO TO A HALF INCH OR LESS.
THE MAIN IMPACT WILL BE TO INVIGORATE THE LES...ESPECIALLY LATE THIS
AFTERNOON AND EVENING...AS DEEPER MOISTURE MOVES IN AND INVERSION
HEIGHTS CLIMB AOA 7K FT WITH 850 MB TEMPS AROUND -19C. WITH THE DGZ IN
THE CONVECTIVE LAYER...SNOW/WATER RATIO VALUES SHOULD ALSO REMAIN
HIGH(FROM 25/1 TO 30/1). VEERING WINDS WILL SHIFT THE FOCUS OF THE
HEAVIER LES TO AREAS BTWN HOUGHTON AND THE PORCUPIN MOUNTAINS AND
ALSO WILL ALLOW THE LES TO PUSH INTO THE EAST (LOCATIONS FROM AU
TRAIN EASTWARD).
ONGOING ADVISORIES AND SNOWFALL AMOUNTS LOOK ON TRACK WITH 12 HOUR
AMOUNTS OF 1 TO 4 INCHES WEST TODAY AND 2 TO 5 INCHES TONIGHT. OVER
THE EAST...1 TO 3 INCHES ARE EXPECTED THIS AFTERNOON WITH AMOUNTS OF
3 TO 6 INCHES POSSIBLE...GREATEST NEAR THE LAKE EAST OF MUNISING.
SOME HIGHER AMOUNTS MAY BE POSSIBLE EAST IF A MORE DOMINANT BAND
DEVELOPS BUT CONFIDENCE IN THE LOCATION IS LIMITED GIVEN SIGNFICNAT
DIFFERENCES BETWEEN THE HIGHER RES MODELS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 426 AM EST SUN JAN 13 2013
WEST TO NORTHWEST FLOW LAKE EFFECT WILL BE ONGOING AT THE START OF
THE LONG TERM PERIOD. BUT WITH THE SURFACE TROUGH OVER EASTERN LAKE
SUPERIOR DIMINISHING DURING THE MORNING DUE TO A HIGH PRESSURE
RIDGE MOVING THROUGH MN...EXPECT THE WINDS TO BACK THROUGH THE DAY
AND BE OUT OF THE WEST-SOUTHWEST BY 00Z TUESDAY. THIS WILL PUSH THE
LAKE EFFECT OFFSHORE OVER THE EAST BY EARLY AFTERNOON AND FOCUS THE
LAKE EFFECT OVER THE KEWEENAW PENINSULA OVER THE WEST. SINCE
INVERSION HEIGHTS ARE STILL IN THE 7-8KFT RANGE AND DELTA-T VALUES
ARE AROUND 22...CONDITIONS ARE FAVORABLE FOR MODERATE SNOW TO
CONTINUE ON MONDAY. WITH THE SOUTHERN EDGE OF THE LAKE EFFECT BAND
BEING AIDED BY ENHANCED CONVERGENCE FROM THE BACKING WINDS...THINK
THERE SHOULD BE AT LEAST ONE STRONGER BAND GRADUALLY DRIFTING NORTH
THROUGH NORTHERN HOUGHTON COUNTY DURING THE DAY. THE BIGGEST
CONCERN WILL BE THE NORTHWARD PUSH IN THE MORNING...WHICH THEN
STALLS IN THE AFTERNOON AS WHAT IS LEFT OF THE SURFACE TROUGH
STALLS OVER THE KEWEENAW. WHERE THIS BAND STALLS OR DOESN/T
STALL WILL DETERMINE SNOWFALL AMOUNTS. BUFKIT SOUNDINGS SHOWING
FAVORABLE CONDITIONS FOR VERY FLUFFY 30-1 SNOW RATIOS...AS THE BEST
OMEGA IS CENTERED RIGHT IN THE DGZ...MUCH OF THE CLOUD IS IN THE
DGZ...AND WIND SPEEDS ARE NOT OVERLY STRONG. WILL FOLLOW THAT IDEA
FOR THE FORECAST AND BUMP RATIOS TOWARDS THAT. WITH THE WAY MODELS
ARE LOOKING...COULD BE A PERIOD OF EVEN HEAVY SNOW DURING THE LATE
MORNING AND AFTERNOON HOURS...SINCE POCKET OF DEEPER H850-700
MOISTURE HELPS PUSH LAKE EFFECT SNOW PARAMETER VALUES WELL OVER 2.
HAVE FINE TUNED THE POPS DURING THIS PERIOD AND BUMPED SNOWFALL
AMOUNTS UP A FEW INCHES. 00Z RUNS OF BOTH THE NESTED 4KM NAM AND OUR
LOCAL WRF-ARW COBB SNOWFALL OUTPUT ARE INDICATING 10IN OF SNOW FOR
KCMX FROM 12Z MONDAY THROUGH 06Z TUESDAY. HAD SOME CONCERN EXTENDING
THE ADVISORY FOR ANOTHER 12HRS SINCE IT WAS A SIGNIFICANT JUMP FROM
PREVIOUS RUNS...BUT WITH GOING FORECAST VALUES OF 3-5 INCHES ON
MONDAY COULDN/T HOLD OFF ON IT.
WITH THE HIGH PRESSURE RIDGE SLIDING EAST ACROSS WISCONSIN ON
MONDAY NIGHT...INDICATIONS ARE THE WINDS BACKING MORE TO THE
SOUTHWEST. THIS WILL PUSH THE STRONGER SNOW TO THE NORTH THROUGH
KEWEENAW COUNTY AND BRING AN END TO THE LES FOR THE CWA FOR
A DAY OR TWO DUE TO H850 TEMPS WARMING TO -10C UNDER THE STRONG
SOUTHWESTERLY FLOW ON TUESDAY.
THIS INCREASING SOUTHWESTERLY FLOW IS IN RESPONSE TO AN APPROACHING
SHORTWAVE AND CLIPPER SYSTEM DROPPING THROUGH THE NORTHWEST FLOW
ALOFT. THIS COULD PRODUCE SOME BREEZY CONDITIONS ON TUESDAY
INTO TUESDAY NIGHT. BOTH NAM/GFS SHOWING H925 WINDS OF
40-50KTS...BUT A WEAK INVERSION MAY BE ENOUGH TO KEEP THAT
FROM REACHING THE SURFACE OVER LAND. OVER LAKE SUPERIOR...BUFKIT
SOUNDINGS SHOWING MUCH OF THAT REACHING THE SURFACE DUE TO STRONG
PRESSURE FALL /14MB IN 12HR/ MOVING ACROSS THE LAKE. THUS...HAVE
BUMPED WINDS UP A SOLID 10KTS TO GALES AND IF LATEST TRENDS ARE
CORRECT THEY WILL NEED TO GO ANOTHER 5-10KTS HIGHER. DEFINITELY
SEEING BETTER AGREEMENT IN THE MODELS WITH THE TIMING/TRACK OF THE
SYSTEM...ALTHOUGH THE ECMWF/GEM ARE A LITTLE FARTHER SOUTH AND
SLOWER WITH AN ELONGATED SURFACE TROUGH AS IT MOVES THROUGH LATE
TUESDAY NIGHT INTO WEDNESDAY. EITHER SOLUTION SHOULD LEAD TO AT
LEAST A DUSTING TO AN INCH OF SNOW CWA WIDE...BUT ECMWF/GEM COULD
PRODUCE SOME AREAS WITH A COUPLE INCHES OF SNOW.
COLD AIR WILL SURGE IN BEHIND THIS CLIPPER...AS THE POLAR VORTEX
DIVES SOUTHEAST TOWARDS JAMES BAY. AT THIS POINT IT LOOKS TO STAY
THERE...BUT IT WILL STILL LEAD TO H850 TEMPS IN THE LOW TO MID -20S.
WITH HIGH PRESSURE CENTERED IN THE CENTRAL PLAINS AND A LOW OVER
HUDSON BAY...EXPECT NORTHWESTERLY WINDS AT THE SURFACE AND THROUGH
H850. THIS WILL LEAD TO PERSISTENT LES IN THAT FAVORED WIND
DIRECTION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. WILL CONTINUE TO
HIGHLIGHT HIGH END LIKELY POPS IN THAT AREA. INTENSITY WILL DEPEND
ON THE INVERSION HEIGHTS AND IF ANY DEEPER MOISTURE OR SHORTWAVES
SWEEP THROUGH. 00Z GFS SHOWING LAKE INDUCED EQL HEIGHTS OF
7-9KFT...BUT MOISTURE REMAINS BELOW 5KFT WITH FORCING ON HIGHER
EDGE OF DGZ. THUS...POTENTIAL IS THERE FOR MODERATE SNOW...BUT
MOISTURE WILL BE CONTROLLING FACTOR.
GFS/ECMWF CONTINUING TO SHOW THE POTENTIAL FOR A WEAK SHORTWAVE
SLIDING THROUGH THE NORTHWEST FLOW ON FRIDAY AND AGAIN ON SATURDAY.
THIS LEADS TO SOME UNCERTAINTY IN THE LAKE EFFECT LOCATIONS AND
JUST LOW END CHANCE OR SLIGHT POPS ACROSS THE REST OF THE CWA.
AFTER A BELOW NORMAL START TO THE WORK WEEK...TEMPERATURES LOOK TO
RETURN TO NORMAL FOR TUESDAY/WEDNESDAY BEFORE FALLING 5-10 DEGREES
BELOW NORMAL FOR THE END OF THE WORK WEEK. FINALLY...00Z GFS HAS
TRENDED TOWARDS WHAT THE ECMWF HAS BEEN SHOWING WITH THE POLAR
VORTEX DIVING SOUTH INTO THE GREAT LAKES ON SUNDAY/MONDAY.
SIGNIFICANT DIFFERENCES IN THE AMOUNT OF COLD AIR BETWEEN THE
MODELS...SO IT WILL BE INTERESTING TO SEE WHICH ONE PANS OUT. IF
ECMWF IS RIGHT...H850 TEMPS WILL BE AROUND -35C AND WOULD LEAD TO
INLAND AREAS ON SLIGHTLY ABOVE ZERO FOR HIGHS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 704 AM EST SUN JAN 13 2013
EXPECT MVFR CONDITIONS TO PREVAIL AT CMX/IWD WITH SURGE OF COLD AIR
OVER THE RELATIVELY WARM WATERS OF LAKE SUPERIOR AND AN UPSLOPE W-NW
WIND. THERE COULD BE SOME HEAVIER SHSN/IFR CONDITIONS MAINLY AT CMX.
SINCE THE NW LOW LEVEL WILL DOWNSLOPE AT SAW...THE MVFR CONDITIONS
MAY GIVE WAY TO VFR AT TIMES. THE APPROACH OF ANOTHER SHORTWAVE
TROUGH THIS AFTERNOON WILL INCREASE CHANCE OF HEAVIER SHSN/IFR
VSBYS AT IWD/CMX IN THE PRESENCE OF AN UPSLOPE WIND. ALTHOUGH SOME
-SHSN MAY IMPACT SAW AS WELL...DOWNSLOPE WIND WILL LIMIT THE POTENTIAL
FOR ANY WORSE THAN MVFR CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 533 AM EST SUN JAN 13 2013
NORTHWEST WINDS ARE EXPECTED TO REMAIN AT OR BELOW 25 KNOTS THROUGH
MONDAY AS HIGH PRESSURE GRADUALLY BUILDS FROM THE PLAINS TOWARD THE
GREAT LAKES. A CLIPPER LOW PRES SYSTEM MOVING INTO SRN MANITOBA
TUESDAY AND NORTHERN ONTARIO TUE NIGHT WILL LIKELY BRING SW GALES
ACROSS LAKE SUPERIOR. AS THE LOW DEEPENS AND MOVES TOWARD NRN QUEBEC
WED...SOME NW GALES MAY ALSO BE POSSIBLE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ006-007.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KF
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1137 AM CST SUN JAN 13 2013
.UPDATE...
UPDATED TO INCLUDE 18Z AVIATION DISCUSSION BELOW.
&&
.DISCUSSION...
/ISSUED 936 AM CST SUN JAN 13 2013/
RECENT RADAR AND SURFACE OBSERVATION TRENDS SHOW A NICE BLOSSOMING
OF LIGHT SNOW ACTIVITY AHEAD OF THE MID-LEVEL TROUGH CURRENTLY
PUSHING ACROSS THE AREA. THIS FEATURE SHOWS UP WELL ON WATER
VAPOR... AND THE RUC HIGHLIGHTS A TIGHT UPPER LEVEL PV GRADIENT
ASSOCIATED WITH IT. GIVEN DEEP LAYER SATURATION AND SOME MODEST
VERTICAL MOTION EXPECT TO SEE OCCASIONAL LIGHT SNOW PERSIST AS THE
SYSTEM MOVES ACROSS THE AREA THROUGH THE DAY. PRECIPITATION
AMOUNTS WILL BE LIMITED... AND DON/T EXPECT MUCH MORE THAN A
DUSTING OR FEW TENTHS OF ACCUMULATION... BUT GIVEN THE FACT THAT
WHITE FROZEN STUFF WILL FALL FROM THE SKY DECIDED TO BUMP POPS UP
INTO THE LIKELY TO CATEGORICAL RANGE FOR LIGHT SNOW.
&&
.AVIATION.../18Z TAF ISSUANCE/
DECENT UPPER LEVEL TROUGH CURRENTLY MOVING THROUGH THE AREA IS
GENERATING SOME LIGHT SNOW AND MAINLY MVFR VISIBILITIES UNDER MVFR
CEILINGS. THIS UPPER WAVE WILL CONTINUE TO PUSH EAST THROUGH THE
AFTERNOON AND EARLY EVENING WITH ANY PCPN ENDING... BUT SOME MID-
HIGH CLOUDS REMAINING. WINDS WILL BACK SLIGHTLY THROUGH MONDAY...
BUT REMAIN FAIRLY LIGHT WITH MINIMAL TO NON-EXISTENT GUSTINESS
EXPECTED. ANOTHER UPPER WAVE IS EXPECTED TO PUSH ACROSS THE AREA
ON MONDAY... WHICH COULD WRING OUT SOME SNOWFLAKES AND SUB-3KFT
CEILINGS ONCE AGAIN... BUT AT THIS POINT CONFIDENCE IS TOO LOW TO
INCLUDE MUCH OF ANYTHING WITH THAT.
KMSP...TAF REFLECTS EXPECTIONS WITH REASONABLY GOOD CONFIDENCE.
MAIN DIFFERENCES WOULD BE IN THE TIMING OF SNOW ENDING THIS
AFTERNOON WHICH COULD VARY BY +/- 1 HOUR.
/OUTLOOK FOR KMSP/
MONDAY NIGHT...OCCASIONAL MVFR CEILINGS POSSIBLE. SOUTHWEST WIND 5
TO 10 KT.
TUESDAY...VFR CONDITIONS EXPECTED. SOUTHWEST WIND INCREASING TO 10
TO 20 KT.
TUESDAY NIGHT...MVFR CEILINGS AND VISIBILITIES POSSIBLE LATE WITH
A CHANCE OF LIGHT SNOW. SOUTHWEST WIND 10 TO 20 KT WITH HIGH GUSTS
POSSIBLE LATE.
WEDNESDAY...MVFR CEILINGS AND VISIBILITIES POSSIBLE EARLY WITH A
CHANCE OF LIGHT SNOW. SOUTHWEST WIND 15 TO 25 KT WITH HIGHER GUSTS
SHIFTING WEST.
WEDNESDAY NIGHT...VFR CONDITIONS EXPECTED. NORTHWEST WIND 10 TO 20
KT.
&&
.PREV DISCUSSION...
/ISSUED 400 AM CST SUN JAN 13 2013/
A MID/UPPER LEVEL TROUGH FROM ONTARIO TO THE CENTRAL PLAINS WILL
MOVE SLOWLY ACROSS THE FA TODAY. CURRENTLY THE CENTER PORTION OF
THE CWA IS CLEAR. HOWEVER... MID LEVEL CLOUDINESS IS EXPANDING
OVER EASTERN SD AND NE. BOTH THE NAM AND GFS SHOW THIS CLOUDINESS
SPREADING ENE THROUGH THE MORNING... WITH PARTLY TO MOSTLY CLOUDY
CONDITIONS OCCURRING. KEPT A MENTION OF FLURRIES TO THE NORTH AND
EAST OF THE TWIN CITIES TODAY WHERE LOW LEVEL CLOUDINESS ALREADY
EXISTS. IT WILL BE A COLD DAY WITH HIGHS IN THE SINGLE DIGITS TO
TEENS. HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT WITH
CLEARING OCCURRING. LOWS ARE FORECAST FROM ZERO TO 10 BELOW.
THE WEEK AHEAD WILL FEATURE A SERIES OF ALBERTA CLIPPER LOW
PRESSURE SYSTEMS. TIMING AND LOCATION ARE IN PRETTY GOOD AGREEMENT
BETWEEN THE GFS AND ECMWF. THE FIRST WILL PASS ALONG OR JUST NORTH
OF THE INTERNATIONAL BORDER TUESDAY NIGHT AND EARLY WEDNESDAY.
THE SREF IS ALREADY SHOWING LIKELY TO CATEGORICAL POPS FOR THE
NORTHERN HALF OF MN AND WI. AT THIS POINT...BLENDED IN THE SREF
WHICH BROUGHT OUR POPS UP INTO THE HIGH CHANCE CATEGORY ACROSS
OUR FAR NORTHERN CWA. SOME LIGHT SNOW ACCUMULATION WOULD CERTAINLY
BE POSSIBLE ALONG AND NORTH OF I-94.
THE COLD FRONT TRAILING THE LOW WILL MOVE THROUGH LATE ON
WEDNESDAY. THIS ALLOWS ANOTHER WEAK LOW TO MOVE ALONG THIS
BOUNDARY THURSDAY NIGHT AND FRIDAY. THIS EVENT IS AGAIN MAINLY
ALONG AND NORTH OF I-94...BUT IT DOES HAVE THE POSSIBILITY OF
GETTING DOWN INTO THE TWIN CITIES FOR THE FRIDAY MORNING COMMUTE
AND WILL NEED TO BE WATCHED.
FINALLY...ANOTHER LOW WILL PASS ALONG THE INTERNATIONAL BORDER
FRIDAY NIGHT AND SATURDAY WITH A PRECIPITATION PATTERN EXPECTED
MUCH LIKE THE TUESDAY NIGHT/WEDNESDAY ONE. ONE THING NOTED IS THAT
THERE WILL BE A PRETTY WARM WESTERLY FLOW ACROSS SOUTHERN MN AND
INTO WI WITH THE SATURDAY LOW PRESSURE SYSTEM AND HIGH
TEMPERATURES IN THE 25 TO 30 DEGREE RANGE MAY NOT BE WARM
ENOUGH...ESPECIALLY WHEN COMPARING THE LOW LEVEL THERMAL PATTERN
FOR WEDNESDAY WITH 35 TO 40 DEGREE TEMPERATURES PROGGED.
IT DOES APPEAR THAT IN THE WAKE OF NEXT WEEKENDS LOW PRESSURE
SYSTEM...THE FLOW PATTERN ALOFT WILL TURN NORTHERLY. THIS COULD
UNLEASH THE COLDEST AIR YET THIS WINTER. ITS POSSIBLE WE COULD SEE
A DAY OR TWO WHERE THE HIGH FAILS TO GET ABOVE ZERO...ESPECIALLY
ACROSS THE CENTRAL AND NORTH WHERE A BETTER SNOWPACK STILL EXISTS
AND MORE COULD BE ADDED THIS WEEK. THIS COULD ALSO JEOPARDIZE THE
RECORD HERE AT MSP WHERE CONSECUTIVE DAYS WITH HIGHS OF ZERO OR
GREATER HAVE OCCURRED FOR NEARLY 4 YEARS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1144 AM CST SUN JAN 13 2013
.SHORT TERM...
ISSUED AT 502 AM CST SUN JAN 13 2013
(TODAY)
THERE ARE TWO MAIN AREAS OF CONCERN WRT PCPN TODAY. THE FIRST IS
NEAR THE FNTL BDRY WHICH MOVED THROUGH THE CWA YESTERDAY AND THE
SECOND IS AN AREA OF FRONTOGENESIS ALONG THE VERTICALLY SLOPED
FRONTAL SFC WHICH IS FCST TO MOVE THROUGH THE CWA TODAY.
A VORT MAX IN THE BASE OF THE LONGWAVE TROF OVER OK/TX IS FCST TO
LIFT NEWD INTO WISCONSIN TODAY WHICH WILL PROVIDE A SOURCE OF LARGE
SCALE LIFT ACROSS THE AREA AS SEEN ON H7-H5 QVECTOR CONVERGENCE
GRAPHICS. A STRONG CDFNT WAS LOCATED SOUTHEAST OF THE CWA EARLY
THIS MORNING AND A SFC WAVE RIDING ALONG THE BDRY OVERNIGHT HAD
PUSHED IT EVEN FARTHER TO THE SOUTHEAST. WIDESPREAD PCPN WAS ALSO
OCCURRING ALONG THE FRONT EARLY THIS MORNING. ANOTHER SFC WAVE IS
FCST TO RIDE NEWD ALONG THE BAROCLINIC ZONE TODAY AND SOME OF THE
FNTL PCPN COULD SPILL OVER INTO THE SERN AND ERN CWA
TODAY...ESPECIALLY IF A PORTION OF THE SFC BDRY LIFTS SLIGHTLY
NWWD AHEAD OF THE SFC WAVE. THE CONCERN HERE IS THAT TEMPERATURE
PROFILES WOULD SUPPORT FREEZING RAIN OVER THIS AREA. THERE ARE NO
STRONG SIGNALS IN THE MODELS TO SUPPORT SUCH A NWWD WOBBLE BUT IF
IT DOES OCCUR OR IF SCT SHRA /SIMILAR TO WHAT WAS OCCURRING OVER
AR BETWEEN 10-11Z/ EXPANDS IN COVERAGE THEN LATER SHIFTS MAY NEED
TO CONSIDER A FREEZING RAIN ADVISORY FOR PARTS OF THE SERN/ERN
CWA.
THE SECOND AREA OF CONCERN WAS A BAND OF FRONTOGENETICALLY FORCED
PCPN OVER NERN OK/SERN KS/WRN MO WHICH APPEARED TO BE OCCURRING
ALONG THE H85-H7 FRONTAL SFC BASED ON THE 09Z RUC ANALYSIS. THIS
AREA OF FORCING IS EXPECTED TO EXPAND/MOVE ACROSS THE CWA TODAY
WITH THE LIFTING VORT MAX AND COULD RESULT IN LIGHT SNOW OR LIGHT
FREEZING RAIN/DRIZZLE SINCE THE FCST FORCING AND MOISTURE OVER OUR
AREA LATER TODAY BOTH LOOK COMPARABLE TO WHAT WAS ALREADY
OCCURRING OVER OK BETWEEN 09-11Z. IN SUMMARY...THE GREATEST
POTENTIAL FOR MEASURABLE -FZRA IS OVER THE SERN/ERN CWA AND A
TRACE OF GLAZING IS POSSIBLE ELSEWHERE. WE WILL ISSUE AN SPS TO
HIGHLIGHT THE POTENTIAL FOR A LIGHT GLAZE SINCE EVEN TRACE AMOUNTS
OF FREEZING RAIN/DRIZZLE CAN BE HAZARDOUS.
TEMPERATURES WILL PROBABLY STRUGGLE TO RISE MUCH ABOVE FREEZING
TODAY IN MOST LOCATIONS DUE TO THE COLD AIR MASS IN PLACE AND
WIDESPREAD CLOUDINESS DURING MOST OF THE DAYLIGHT HOURS.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 210 AM CST SUN JAN 13 2013
(TONIGHT - TUESDAY NIGHT)
SW UPPER LEVEL FLOW WILL PREVAIL ACROSS THE REGION DURING THIS TIME
WITH A WEAK UPPER LEVEL DISTURBANCE MOVING THRU MONDAY AND THE
HEAVILY SHEARED REMNANTS FROM THE LONGWAVE TROF BASE ON TUESDAY AND
TUESDAY NIGHT. WHILE THIS PATTERN ALONE MAY TRY TO GIVE THE
SEMBLANCE OF AN ACTIVE PATTERN WITH ADDITIONAL CHANCES FOR PCPN...
THE SFC PATTERN WILL ALL BUT SQUASH THAT...WITH HI PRES DOMINATING
UNDERNEATH AND MAINTAINING VERY DRY AIR THRU THE COLUMN.
THE SFC HI THAT WILL DOMINATE THIS PERIOD WILL ALSO KEEP US BELOW
AVERAGE...ABOUT 10 DEGREES BELOW ON MONDAY AND 5 DEGREES BELOW ON
TUESDAY...AS THE AIRMASS SLOWLY MODERATES. MOS LOOKS A BIT TOO COLD
FOR MAXES BOTH DAYS...PERHAPS FROM OVERESTIMATING/ANTICIPATING SNOW
COVER FROM YESTERDAY/S SYSTEM...AND LEANED WARM VERSUS THEM.
(WEDNESDAY - SATURDAY)
A BIT OF A PATTERN SHIFT OF SOME NOTE OCCURS EARLY IN THIS PERIOD
WITH LONGWAVE TROF SHIFTING TO THE ERN CONUS...ALBEIT NOT QUITE WHAT
IT WAS WHEN IT WAS OVER THE W...AND IS ANTICIPATED TO BE GREATLY
DE-AMPLIFIED. THIS WILL GIVE US A W-NW FLOW AND IS EXPECTED TO BE
MARKED BY LITTLE OR NO WX-MAKING DISTURBANCES OF NOTE AND TEMPS AT
OR ABOVE AVERAGE.
ONCE WE GET IN THIS PATTERN...IT LOOKS LIKE IT WILL STAY FOR A WHILE
AS VERY LATE IN THIS PERIOD AMPLIFICATION OF THE RIDGE WILL TAKE
PLACE OVER THE WRN CONUS AND THIS WILL CAUSE A CORRESPONDING
DEEPENING OF THE TROF IN THE E. IF THIS HOLDS...SEVERAL WAVES OF
NOTABLE COLD COULD COME OUT OF THIS. BUT IF YOU ARE LOOKING FOR
SNOW...SYSTEMS TO TAKE ADVANTAGE OF THIS APPEAR SCARCE.
TES
&&
.AVIATION...
ISSUED AT 1134 AM CST SUN JAN 13 2013
STORM SYSTEM IS PULLING AWAY FROM THE AREA THIS AFTERNOON...BUT
THERE`S STILL SOME LINGERING AVIATION CONCERNS ESPECIALLY OVER
SOUTH CENTRAL ILLINOIS. EXPECT PRIMARILY MVFR FLIGHT CONDITIONS TO
PREVAIL EXCEPT OVER SOUTH CENTRAL ILLINOIS WHERE IFR CIGS/VSBYS
WILL CONTINUE UNTIL 20-21Z. PERIODS OF SLEET AND/OR FREEZING RAIN
WILL CONTINUE IN THOSE AREAS AS WELL WHICH WILL LIKELY CAUSE LIGHT
ICING ON ELEVATED SURFACES. ONCE THIS PRECIP CLEARS THE AREA
SHOULD SEE CONDITIONS IMPROVE TO MVFR. CIGS WILL CLEAR THE AREA
FROM WEST TO EAST LATE THIS AFTERNOON AND OVERNIGHT AS HIGH
PRESSURE BUILDS ACROSS THE AREA. VFR FLIGHT CONDITIONS ARE
EXPECTED AS THE HIGH BUILDS OVERHEAD.
SPECIFICS FOR KSTL...
LOOKS LIKE PRECIPITATION IS ABOUT DONE AT LAMBERT. CAN`T RULE OUT
AN OCCASIONAL ICE PELLET OR SNOW GRAIN AS THE STORM SYSTEM
CONTINUES PULLING EASTWARD...BUT RADAR ISN`T SHOWING ANY
SIGNIFICANT PRECIP SOUTHWEST OF THE TERMINAL. MVFR CIGS WILL
LIKELY PREVAIL THROUGH THE AFTERNOON INTO EARLY EVENING. UNSURE AT
THIS TIME EXACTLY WHEN THE CIGS WILL SCATTER AND CLEAR OUT...BUT
IT LOOKS LIKE MID TO LATE EVENING AT THIS TIME. VFR CONDITIONS ARE
EXPECTED TO PREVAIL AFTER THE CIGS CLEAR AS A STRONG SURFACE HIGH
BUILDS ACROSS THE REGION.
CARNEY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
252 PM CST SUN JAN 13 2013
.MESOSCALE UPDATE...
COLD FRONT CRAWLING THROUGH THE MID STATE AT MID-AFTERNOON WITH
COLDER AIR JUST ABOUT ON NASHVILLE. CLARKSVILLE DOWN TO 40 DEGREES
AT 2 PM WITH CROSSVILLE STILL AT 61 DEGREES. LARGE AREA OF RAIN
COVERING THE WEST HALF OF MIDDLE TENNESSEE WITH A GOOD FEED
CONTINUING OUT OF MISSISSIPPI UP INTO MIDDLE TENNESSEE. STILL
HAVE SOME EMBEDDED THUNDERSTORMS AND THEY HAVE BEEN MOSTLY ALONG
THE LEADING EDGE OF THE RAIN AREA. ANOTHER THREE QUARTERS TO AN INCH
OF RAIN LIKELY IN A 75 MILE WIDE CORRIDOR ALONG INTERSTATE 65 OVER
THE NEXT 3 TO 4 HOURS WITH THE RAIN AREA SHIFTING EAST WITH
TIME...BUT SLOWLY. TEMPS WILL REMAIN QUITE WARM OVER EASTERN
MIDDLE TENNESSEE AND PLATEAU INTO THE EVENING BEFORE FRONT
ARRIVES.
BOYD
&&
.PREV DISCUSSION... /ISSUED 128 PM CST SUN JAN 13 2013/
DISCUSSION...
BULK OF THE RAIN TODAY HAS BEEN OVER THE WESTERN HALF THE MID
STATE WITH SEVERAL FLASH FLOOD WARNINGS BEING ISSUED. THE RIVERS
HAVE RESPONDED QUITE WELL BY CARRYING THE RUNOFF DURING THE DAY
WITH THE HARPETH AT KINGSTON SPRING BEING THE ONLY RIVER AT TIME
OF THIS WRITING THAT HAS JUMPED TO THE 14 FOOT LEVEL WHICH IS
STILL WELL BELOW THE FLOOD STAGE OF 20 FEET. THE HARPETH IS
CONTINUING TO RISE AND IS FORECAST TO REACH THE 20 FOOT LEVEL
AROUND DAYBREAK MONDAY.
SYNOPICALLY THE FRONT EXTENDED FROM JUST WEST OF BOWLING GREEN
DOWN BETWEEN NASHVILLE AND CLARKSVILLE TO TUPELO MISSISSIPPI. THE
FRONT HAS A SERIES OF WAVES THAT WILL RIDE UP THE FRONT DURING THE
AFTERNOON AND EARLY EVENING AND THIS WILL KEEP THE FRONT IN THE
MID STATE A LITTLE LONGER THAN PREVIOUSLY THROUGHT. EVENTUALLY THE
FRONT WILL WORK EASTWARD AND BE ALONG THE PLATEAU AROUND 00Z BASED
ON THE LATEST RUC RUN. MUCH OF THE RAIN IS POST FRONTAL. WILL KEEP
HIGH POPS GOING THROUGH THE EVENING ACROSS ALL OF THE MID STATE
AND THEN LOWER THE POPS FROM THE WEST AFTER MIDNIGHT. MUCH COLDER
TEMPERATURES TONIGHT AND MONDAY AND I HAVE PLACE A MIX OF RAIN AND
SLEET OVER THE NORTHWEST HALF OF THE MID STATE AFTER MIDNIGHT AND
OVER THE NORTH HALF DURING THE DAY MONDAY. MONDAY WILL BE A COLD DAY
WITH HIGHS IN THE 30S. WAVES ALONG THE FRONTAL BOUNDARY TO OUR
SOUTH WILL KEEP PRECIP CHANCES GOING THROUGH TUESDAY NIGHT.
WEDNESDAY THROUGH THE REMAINDER OF THE WEEK LOOKS BASICALLY DRY AS
HIGH PRESSURE REMAINS OVER THE AREA INTO THE WEEKEND. A SYSTEM DOES
DEVELOP IN THE GULF ON THURSDAY BUT THINK IT WILL REMAIN FAR
ENOUGH SOUTH NOT TO BRING PRECIP TO THE MID STATE.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR TNZ005>011-022>034-
056>066-075-077>080-093>095.
&&
$$
BOYD
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
128 PM CST SUN JAN 13 2013
.DISCUSSION...
BULK OF THE RAIN TODAY HAS BEEN OVER THE WESTERN HALF THE MID
STATE WITH SEVERAL FLASH FLOOD WARNINGS BEING ISSUED. THE RIVERS
HAVE RESPONDED QUITE WELL BY CARRYING THE RUNOFF DURING THE DAY
WITH THE HARPETH AT KINGSTON SPRING BEING THE ONLY RIVER AT TIME
OF THIS WRITING THAT HAS JUMPED TO THE 14 FOOT LEVEL WHICH IS
STILL WELL BELOW THE FLOOD STAGE OF 20 FEET. THE HARPETH IS
CONTINUING TO RISE AND IS FORECAST TO REACH THE 20 FOOT LEVEL
AROUND DAYBREAK MONDAY.
SYNOPICALLY THE FRONT EXTENDED FROM JUST WEST OF BOWLING GREEN
DOWN BETWEEN NASHVILLE AND CLARKSVILLE TO TUPELO MISSISSIPPI. THE
FRONT HAS A SERIES OF WAVES THAT WILL RIDE UP THE FRONT DURING THE
AFTERNOON AND EARLY EVENING AND THIS WILL KEEP THE FRONT IN THE
MID STATE A LITTLE LONGER THAN PREVIOUSLY THROUGHT. EVENTUALLY THE
FRONT WILL WORK EASTWARD AND BE ALONG THE PLATEAU AROUND 00Z BASED
ON THE LATEST RUC RUN. MUCH OF THE RAIN IS POST FRONTAL. WILL KEEP
HIGH POPS GOING THROUGH THE EVENING ACROSS ALL OF THE MID STATE
AND THEN LOWER THE POPS FROM THE WEST AFTER MIDNIGHT. MUCH COLDER
TEMPERATURES TONIGHT AND MONDAY AND I HAVE PLACE A MIX OF RAIN AND
SLEET OVER THE NORTHWEST HALF OF THE MID STATE AFTER MIDNIGHT AND
OVER THE NORTH HALF DURING THE DAY MONDAY. MONDAY WILL BE A COLD DAY
WITH HIGHS IN THE 30S. WAVES ALONG THE FRONTAL BOUNDARY TO OUR
SOUTH WILL KEEP PRECIP CHANCES GOING THROUGH TUESDAY NIGHT.
WEDNESDAY THROUGH THE REMAINDER OF THE WEEK LOOKS BASICALLY DRY AS
HIGH PRESSURE REMAINS OVER THE AREA INTO THE WEEKEND. A SYSTEM DOES
DEVELOP IN THE GULF ON THURSDAY BUT THINK IT WILL REMAIN FAR
ENOUGH SOUTH NOT TO BRING PRECIP TO THE MID STATE.
&&
.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE 30 37 28 44 / 70 30 40 40
CLARKSVILLE 24 33 24 41 / 70 30 20 20
CROSSVILLE 36 43 33 45 / 100 70 70 70
COLUMBIA 31 38 29 44 / 70 50 40 40
LAWRENCEBURG 32 38 30 44 / 100 70 40 40
WAVERLY 25 35 25 40 / 70 30 20 20
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR TNZ005>011-022>034-
056>066-075-077>080-093>095.
&&
$$
BOYD
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1200 PM CST SUN JAN 13 2013
.UPDATE...
AN UPDATE WAS SENT AT MID MORNING REMOVING THE PRECIPITATION FROM
TODAYS FORECAST. SKIES HAVE NEARLY CLEARED ACROSS ALL BUT THE
SOUTHEASTERN COUNTIES AS OF 1730Z. HAVE JUST SENT ANOTHER QUICK
UPDATE TO ADJUST THE HOURLY TRENDS.
58
&&
.AVIATION...
NORTHWESTERLY WINDS AROUND 10 TO 20 KNOTS WILL CONTINUE FOR MOST
OF THE PERIOD...BECOMING NORTHERLY TOMORROW. MOSTLY CLEAR SKIES
WILL PREVAIL FOR MOST OF THE PERIOD...BUT SCT/BKN MID CLOUDS ARE
POSSIBLE TOMORROW AS A DISTURBANCE PASSES OVER NORTH TEXAS. NO
PRECIPITATION IS EXPECTED...DUE TO VERY DRY AIR IN THE LOWER
ATMOSPHERE.
HAMPSHIRE
&&
.PREV DISCUSSION... /ISSUED 425 AM CST SUN JAN 13 2013/
SHORT TERM WINTER WEATHER/FORECAST CONCERNS...
DID NOT MAKE ANY SIGNIFICANT CHANGES TO THE FORECAST FROM THE 139
AM CST FORECAST UPDATE/AFD. THERE IS STILL NO MODEL GUIDANCE THAT
HAS A GOOD HANDLE ON WINTRY PRECIPITATION FALLING NORTHWEST OF THE
METROPLEX EARLY THIS MORNING. THE HRRR IS CLOSEST...BUT DOESNT
SEEM TO KNOW WHAT IS CAUSING THE WINTRY PRECIPITATION. THE HRRR
CONSISTENTLY INITIALIZES THE RADAR RETURNS AND THEN ALLOWS THEM TO
DISSIPATE SHORTLY THEREAFTER WHICH IS A GOOD SIGN THAT THE MODEL
IS NOT RESOLVING THE FORCING MECHANISM THAT IS RESPONSIBLE FOR THE
PRESENCE OF THE PRECIPITATION. AT ANY RATE...DRAWING BACK ON
MORNING UPDATE DISCUSSIONS...THE GFS FORECAST THAT H700 CONFLUENCE
WOULD DISSIPATE EARLY THIS MORNING SEEMS TO BE SPOT ON ACCORDING
TO REGIONAL VWP OUTPUT. THE BEST H700 CONFLUENCE HAD MOVED NORTH
OF THE RED RIVER AS OF 09Z...AND LIGHT WINTRY PRECIPITATION WAS
LIFTING NORTHEAST AS WELL. THERE IS STILL SOME CONCERN FOR H800
FRONTOGENETIC FORCING ALONG A SHERMAN TO FORT WORTH TO GRANBURY
LINE AROUND SUNRISE RESULTING IN SOME SHALLOW CONVECTION
INITIATION. THE GFS CONTINUES TO ADVERTISE THIS FORCING FOR
ASCENT NEAR THE H800 LEVEL WITH A 100 MB LAYER ABOVE IT
CHARACTERIZED BY DECREASING THETA-E TEMPERATURES WITH
HEIGHT (ESSENTIALLY POSITIVE CAPE).
THAT SAID...THERE IS NO OBSERVATIONAL EVIDENCE THAT STRONG LIFT IS
OCCURRING AT THIS TIME AS THERE ARE NO RAPIDLY COOLING CLOUD TOPS
OR LIGHT MID-LEVEL RADAR REFLECTIVITY RETURNS OVER THESE AREAS AT
THE TIME OF THIS DISCUSSION. THEREFORE WILL NOT BE ISSUING A
FREEZING RAIN ADVISORY FROM SHERMAN...THROUGH THE DFW METROPLEX
AND SOUTHWEST TOWARDS GRANBURY AT THIS TIME. OF COURSE WE WILL
CONTINUE TO MONITOR THIS SITUATION CLOSELY THROUGH SUNRISE AS ANY
DEVELOPING PRECIPITATION WILL LIKELY BE COMPOSED OF SUPERCOOLED
WATER. WHILE THIS WOULD FALL IN LIQUID FORM...IT WOULD FREEZE
IMMEDIATELY UPON CONTACT WITH ANY SURFACE THAT IS ALSO AT OR BELOW
FREEZING. AT THIS TIME IT LOOKS AS THOUGH MOST PRECIPITATION
DEVELOPMENT WILL REMAIN SOUTHEAST OF THIS LINE THROUGH
SUNRISE...DIMINISHING THE THREAT FOR FREEZING RAIN OR SLEET.
TODAY THROUGH MONDAY...ALL GUIDANCE INDICATES THAT LOW-LEVEL
FRONTOGENETIC FORCING WILL DIMINISH IN INTENSITY THIS MORNING AS
DRY AIR AND SUBSIDENCE CONTINUE TO SLOWLY WORK INTO THE REGION.
DRY AIR NEAR THE SURFACE HAS ALREADY PENETRATED AS FAR SOUTHEAST
AS AN ATHENS TO TEMPLE LINE...BUT IT IS THE MOISTURE ALOFT THAT WE
HAVE TO WORRY ABOUT EARLY THIS MORNING. EXPECT ALL LIGHT RAIN/RAIN
SHOWERS TO MOVE EAST AFTER 18Z. DID KEEP IN A 20 PERCENT CHANCE
FOR A RAIN/SLEET MIX FOR LOCATIONS ALONG AND NORTH OF A
GAINESVILLE TO MCKINNEY TO COOPER LINE AFTER SUNRISE JUST IN CASE
THE H800 FRONTOGENESIS SCENARIO DESCRIBED ABOVE PANS OUT. THESE
LOCATIONS WOULD ALSO HAVE TO BE INCLUDED IN A BRIEF FREEZING RAIN
ADVISORY IF THIS PRECIPITATION DOES MANAGE TO DEVELOP AROUND/JUST
BEFORE SUNRISE. IF IT DOES NOT...THESE AREAS WILL LIKELY REMAIN
DRY THIS MORNING.
WE SHOULD SEE SOME SUNSHINE BY LATE THIS AFTERNOON...HOWEVER NOT
MUCH OF A WARM-UP IS EXPECTED TODAY AS NORTH WINDS AND MORNING
CLOUD COVER HELP TO KEEP TEMPERATURES IN THE LOWER TO MID 40S FOR
HIGHS FOR MOST LOCATIONS. FOR TONIGHT...ANOTHER STRONG SHORTWAVE
TROUGH IS EXPECTED TO MOVE OVER THE SOUTH PLAINS. THIS TROUGH WAS
OVER THE SOUTHERN CA COAST PER EARLY MORNING WATER VAPOR IMAGERY.
THIS TROUGH HAS A WELL-DEFINED CYCLONIC CIRCULATION IN WATER VAPOR
IMAGERY AND IS PROGGED TO SEND STRONG LARGE SCALE FORCING FOR
ASCENT OVER THE REGION AS IT MOVES NORTHEAST TONIGHT AND INTO
MONDAY MORNING.
FOR MOST OF NORTH TX...THIS STRONG FORCING FOR ASCENT IS EXPECTED
TO GO UNNOTICED AS DRY AIR AND SUBSIDENCE ARE EXPECTED TO HAVE
LEFT THE ATMOSPHERE RELATIVELY STABLE BY LATE TONIGHT.
HOWEVER...THE GFS/NAM/ECMWF ALL SHOW RELATIVELY STRONG AND
PERSISTENT ISENTROPIC LIFT ON THE 305 K SURFACE IN BETWEEN 06 AND
12Z MONDAY MORNING OVER THE FAR SOUTHEASTERN COUNTIES OF THE CWA.
MODELS DO NOT SHOW MUCH IN THE WAY OF QPF...HOWEVER MID-LEVEL
MOISTURE WILL LIKELY RESIDE NEAR THE GULF COAST BEFORE THIS TROUGH
MOVES OVER THE REGION TONIGHT. IT SEEMS REASONABLE THAT SOME OF
THIS MOISTURE WILL RETURN ON THE 305K SURFACE (NEAR THE H700 LEVEL
TONIGHT) AND RESULT IN SOME PERSISTENT MID-LEVEL PRECIPITATION
PRODUCTION BEFORE SUNRISE MONDAY.
THE LOWER TROPOSPHERE IS EXPECTED TO BE QUITE DRY BEFORE THIS
PROCESS STARTS...SO A SIGNIFICANT AMOUNT OF THIS MID-LEVEL
PRECIPITATION IS LIKELY TO EVAPORATE BEFORE REACHING THE GROUND.
REGARDLESS...CONFIDENCE IN THE MID-LEVEL PRECIPITATION PRODUCTION
IS HIGH...SO WENT AHEAD AND MENTIONED A 20 PERCENT CHANCE OF RAIN
OR FREEZING RAIN SOUTHEAST OF AN ATHENS TO TEMPLE LINE (NOT
INCLUDING WACO AT THIS TIME) FOR EARLY MONDAY MORNING. DO NOT
THINK THE IMPACTS OF THIS WILL BE HIGH UNLESS THE LOWER ATMOSPHERE
SATURATES QUICKER THAN EXPECTED. LIGHT PRECIPITATION WILL LIKELY
CONTINUE AFTER SUNRISE MONDAY MORNING FOR THESE
LOCATIONS...HOWEVER TEMPERATURES ARE LIKELY TO WARM ABOVE FREEZING
AFTER SUNRISE. WE MAY HAVE TO CONSIDER A WINTER WEATHER OR
FREEZING RAIN ADVISORY IF IT LOOKS LIKE MORE PRECIPITATION WILL
MAKE IT TO THE GROUND...BUT CONFIDENCE IS TOO LOW TO GO WITH
ANYTHING AT THIS TIME.
FOR MID-WEEK...THE ECMWF HAS COME MORE IN LINE WITH THE NAEFS
SOLUTION INDICATING THAT THE LONGWAVE TROUGH OVER THE WESTERN
THIRD OF THE CONUS WILL CONSOLIDATE AND MOVE EAST AS A POSITIVELY
TILTED TROUGH TUESDAY NIGHT INTO WEDNESDAY. THIS SOLUTION LIMITS
LARGE SCALE FORCING FOR ASCENT OVER NORTH AND CENTRAL TX BY
KEEPING LOW LEVEL FLOW VEERED AS IT MOVES OVER THE AREA. THIS
WOULD ALSO PREVENT ANY SIGNIFICANT MOISTURE FROM RETURNING TO THE
REGION OUT AHEAD OF THIS UPPER TROUGH. THE 00 AND 06Z NAM
SOLUTIONS BOTH PREFER THE STRONG AND SLOW MOVING CUT-OFF LOW
SOLUTION ADVERTISED BY THE ECMWF THE PAST FEW DAYS. WHILE THIS
SOLUTION IS AN OUTLIER SOLUTION...WE WILL CONTINUE TO WATCH FOR
ANY SIGN THAT THIS SOLUTION COULD VERIFY AS IT WOULD LIKELY ALLOW
FOR A SIGNIFICANT ICE STORM IN THE REGION IF IT VERIFIED. THIS
FORECAST CONTINUES TO SIDE WITH THE CONSENSUS OF THE NAEFS AND THE
13/00Z ECMWF AS THIS IS BY FAR THE MOST LIKELY OUTCOME. HOWEVER
WILL NOT COMPLETELY IGNORE THE NAM AS IT WOULD BRING A HIGH IMPACT
WINTER WEATHER EVENT TO SOME PART OF NORTH OR CENTRAL TX.
EXTENDED...ONCE THE LONGER WAVE TROUGH MOVES OUT OF THE
REGION...WE SHOULD SEE A SLOW WARMING TREND FOR THE REGION AS A
BLOCKING RIDGE SETS UP OVER THE WESTERN CONUS COAST KEEPING MORE
OR LESS NORTHWEST AND CONFLUENT FLOW OVER THE SOUTH PLAINS. THIS
WARM UP COULD COME TO AN ABRUPT END EARLY NEXT WEEK AS BOTH THE
GFS AND THE ECMWF HAVE A STRONG COLD FRONT MOVING SOUTH THROUGH
THE GREAT PLAINS. THE GFS COOLS US DOWN...BUT ALLOWS THE COLD AIR
TO MODIFY TO THE POINT THAT IT BEHAVES LIKE A TYPICAL WINTER COLD
FRONT FOR TEXAS. THAT IS WE COOL DOWN SIGNIFICANTLY...BUT
OVERNIGHT LOWS TEND TO SAY IN THE MID TO UPPER 20S WHILE HIGHS
CLIMB ABOVE FREEZING.
THE ECMWF BRINGS A SIGNIFICANT ARCTIC OUTBREAK SOUTH THROUGH THE
PLAINS...WHICH WOULD IMPACT NORTH TX SUNDAY NIGHT OR MONDAY IF IT
VERIFIED. THE 13/00Z ECMWF HAS A 1053 MB (MSLP) SURFACE HIGH
BARRELING SOUTH INTO THE CENTRAL PLAINS BEHIND THIS FRONT...WHICH
IS A SIGN OF A VERY COLD ARCTIC AIR INVASION OF THE PLAINS. THIS
IS NOT THE MOST LIKELY SOLUTION TO VERIFY AT THIS TIME...BUT IT
BEARS WATCHING AS WE GET CLOSER TO NEXT WEEKEND AND EARLY NEXT
WEEK. THE ECMWF WOULD BRING LOWS DOWN INTO THE TEENS IF NOT LOWER
ACROSS NORTH TX WHICH COULD CERTAINLY HAVE A BIG IMPACT ON THE
REGION. THIS IS SLIGHTLY BEYOND THE OFFICIAL FORECAST PERIOD AT
THIS TIME...SO WILL WATCH FOR MORE CONSISTENCY AMONGST MODELS
BEFORE JUMPING ON AN ARCTIC OUTBREAK TO START OFF THE NEXT WORK
WEEK.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 42 26 44 28 45 / 10 10 5 10 10
WACO, TX 45 27 43 27 45 / 10 10 10 10 10
PARIS, TX 42 25 44 26 43 / 30 10 10 10 10
DENTON, TX 42 24 43 23 45 / 10 10 5 10 10
MCKINNEY, TX 42 24 44 24 43 / 30 10 10 10 10
DALLAS, TX 42 27 44 29 44 / 10 10 10 10 10
TERRELL, TX 44 26 43 27 43 / 20 10 10 10 10
CORSICANA, TX 44 28 44 30 43 / 10 10 10 10 10
TEMPLE, TX 46 27 43 27 44 / 10 10 10 10 10
MINERAL WELLS, TX 42 22 43 22 44 / 5 10 5 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
85/58
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1121 AM CST SUN JAN 13 2013
.AVIATION...
VFR CONDITIONS EXPECTED DURING THE DAY TODAY AS LIGHT NORTHERLY
WINDS VEER TO A MORE EASTERLY COMPONENT BY TONIGHT. IT IS
THEREFORE POSSIBLE FOR FEW MVFR CLOUD DECKS TO FORM TONIGHT...ALTHOUGH
THE SIGNAL FOR THIS OCCURRENCE DOES NOT APPEAR TO BE OVERLY
STRONG. HAVE OPTED TO CONTINUE A MENTION IN THE TAF AND WILL OF
COURSE AMEND AS NECESSARY. ALSO TONIGHT...AN UPPER LEVEL WEAK
DISTURBANCE MOVING ACROSS THE REGION MAY PROMOTE A CHANCE FOR
FLURRIES/-SN JUST WEST OF KLBB. CONFIDENCE OF THIS HAPPENING AT
ALL IS LOW AND WILL THEREFORE NOT ADD A PRECIP MENTION ATTM.
&&
PREV DISCUSSION... /ISSUED 354 AM CST SUN JAN 13 2013/
SHORT TERM...
A SPRAWLING AND COMPLEX UPPER LEVEL TROUGH WAS DOMINATING THE
WESTERN 2/3RDS OF THE CONUS...WITH SEVERAL EMBEDDED DISTURBANCES
NOTED WITHIN IT. ONE SUCH SHORTWAVE TROUGH WAS GRAZING THE AREA
EARLY THIS MORNING...WITH ANOTHER CURRENTLY DIVING DOWN THE SOUTHERN
CALIFORNIA COAST PROGGED TO APPROACH FROM THE WEST LATE TONIGHT. THE
FORMER HAS PROVIDED STRONG ENOUGH LIFT TO PRODUCE A BAND OF SNOW
THAT HAS TRAVERSED THE NORTHWEST AND NORTH-CENTRAL ZONES EARLY THIS
MORNING. EVEN THOUGH THE PRESENTATION ON RADAR WITHIN THIS BAND HAS
NOT BEEN OVERLY IMPRESSIVE AND MOISTURE IS RATHER LIMITED...THE BAND
HAS BEEN ABLE TO SQUEEZE OUT EFFICIENT SNOW RATES GIVEN THE COLD
TEMPERATURES AND HIGH SNOW TO LIQUID RATIOS. FRIONA REPORTED A QUICK
1-2 INCHES OF SNOW AS THE BAND MOVED THROUGH EARLIER THIS
MORNING...WITH DIMMITT AND TULIA REPORTING LESS THAN 1 INCH. LIFT
SUPPORTING THIS BAND WILL GRADUALLY WANE MOVING TOWARDS
DAYBREAK...BUT A LITTLE LIGHT SNOW OR FLURRIES COULD LINGER PAST 12Z
ACROSS THE NORTHEAST ZONES.
OTHERWISE...COLD SFC RIDGING WILL DOMINATE THE REGION THROUGH THE
SHORT TERM. LOW STRATUS CLOUDS HAVE DEVELOPED ACROSS ROUGHLY THE
NORTHWEST HALF OF THE CWA IN THIS REGIME EARLY THIS MORNING. BOTH
THE NAM AND GFS SUGGEST THESE CLOUDS WILL QUICKLY SCATTER OUT THIS
MORNING AS MID- AND UPPER-LEVEL SUBSIDENCE INCREASES IN THE WAKE OF
THE PASSING SHORTWAVE TROUGH. ON THE OTHER HAND...THE RUC AND HRRR
SUGGEST THAT THE LOW CLOUDS MAY HANG ON MUCH OR ALL OF THE DAY ON
THE CAPROCK AS WINDS VEER EASTERLY AND THE SHALLOW BUT RELATIVELY
MOIST UPSLOPE FLOW ENSUES. CURRENT FORECAST IN THE GRIDS DOES
INDICATE CLEARING SKIES BY MIDDAY...BUT IF THIS DOES NOT
OCCUR...FORECAST HIGHS WILL LIKELY BE TOO HIGH. REGARDLESS...IT WILL
BE A CHILLY DAY AND HAVE FAVORED THE LOW SIDE OF MOS GUIDANCE WITH
FORECAST HIGHS IN THE LOWER TO MIDDLE 30S FOR ALL BUT THE NORTHWEST
ZONES WHERE UPPER 20S WERE CARRIED.
CHILLY EASTERLY UPSLOPE FLOW WILL CONTINUE THROUGH TONIGHT. PROGGED
SOUNDINGS INDICATE MOSTLY CLEAR SKIES EARLY ON...WITH SOME MID-LEVEL
CLOUDS VISITING AT LEAST THE NORTHWEST ZONES LATE AS THE NEXT
SHORTWAVE TROUGH RACES BY. HOWEVER...GIVEN THE UPSLOPE FLOW WOULD
NOT BE SURPRISED IF SOME LOWER CLOUDS DEVELOP OR PERSIST. ALTHOUGH
MODELS ARE GENERALLY DRY...THINK THERE MAY BE ENOUGH LIFT AND
MOISTURE TO SQUEEZE OUT A FEW FLURRIES ACROSS THE WESTERN ZONES LATE
TONIGHT AND HAVE INSERTED THIS INTO THE FORECAST. EXTENT AND
DURATION OF ANY CLOUD COVER COULD HAVE SOME IMPACTS ON EXACTLY HOW
COLD IT GETS TONIGHT...BUT EITHER WAY IT WILL BE CHILLY AND HAVE
MAINTAINED LOWS 10-15 DEGREES BELOW MID-JANUARY AVERAGES /RANGING
FROM 9 DEGREES NORTHWEST TO MID-TEENS OUT EAST/.
LONG TERM...
THE MON THRU THU FORECAST HINGES ON THE STRENGTH AND TRACK OF THE
SRN PORTION OF THE UPPER-LEVEL TROUGH...INITIALLY LOCATED OVER AZ
AND NM MONDAY MORNING. THE MAJORITY OF GUIDANCE ELONGATES THE TROUGH
FROM THE SW TO NE AS IT SLIDES SEWD ACROSS WEST TEXAS...WITH
MOISTURE AND LIFT BOTH LACKING TO WRING OUT ANY PRECIPITATION FOR
OUR AREA...BEFORE IT EVENTUALLY CLOSES OFF AT 500 MB ACROSS NORTH
CENTRAL TX. HOWEVER...THERE ARE STILL A FEW MODELS /E.G. 0Z NAM
AND CMC/ AND SOME GEFS ENSEMBLE MEMBERS THAT CLOSED OFF TROUGH
INTO A CUTOFF LOW ACROSS SRN NM OR NRN MX...THEN TRACK IT SLOWLY
EAST ACROSS WEST TEXAS MID-WEEK. IN THE LATTER CASE COULD BRING
A CHANCE OF SOME RAIN OR SNOW IN THE TUE THRU THU TIME FRAME AS
BOTH MOISTURE ADVECTION AND LIFT WOULD BE ENHANCED. BUT
PREPONDERANCE OF GUIDANCE SUGGESTS THE OPEN WAVE PASSAGE
ACCOMPANIED BY ONLY AN INCREASE IN MID-LVL CLOUD COVER. THUS WE/VE
KEPT POPS BELOW MENTION THROUGH THE EXTENDED PERIOD...ALTHOUGH
NUDGED THEM UP TO 10 PERCENT ACROSS OUR SRN ZONES. MONDAY STILL
APPEARS TO BE THE COOLEST DAY IN THE PERIOD...WITH HIGHS ONLY IN
THE LOW TO MID 30S. TUESDAY WILL ONLY BE SLIGHTLY WARMER...WITH
HIGHS IN THE UPPER 30S TO LOW 40S. FINALLY...BARRING THE CLOSED
LOW SOLUTION...HIGHS WILL WARM BACK INTO THE UPPER 40S AND 50S WED
AND THU.
FRI-SAT: AFTER THE TROUGH/LOW PASSES...WEAK ZONAL TO SW FLOW SHOULD
EXTEND OVER THE AREA AS A BROAD LOW-AMPLITUDE TROUGH DEVELOPS OVER
THE DESERT SOUTHWEST. SOME SUB-TROPICAL MOISTURE MAY GET DRAWN UP BY
THE TROUGH TO BRING SOME HIGH CLOUD COVER TO THE AREA BY FRIDAY. AND
JUST TO OUR NORTH...UPPER FLOW WILL BECOME CYCLONIC AS A DEEP
TROUGH DROPS INTO THE GREAT LAKES REGION...WHILE THE UPPER RIDGE
RE-AMPLIFIES ALONG THE PACIFIC COAST. TEMPS WILL CONTINUE TO BE
MILD WITH HIGHS MAINLY IN THE MID TO UPPER 50S.
A WEAK FRONT IS EXPECTED TO MOVE INTO THE AREA BY SUNDAY...RESULTING IN
A MODEST COOL DOWN DEPENDING ON THE TIMING OF THE FROPA. A MUCH
STRONGER FRONT IS POSSIBLE BY MONDAY THE 21ST...AS A 1050MB SFC RIDGE
DIVES OUT OF CENTRAL CANADA INTO THE PLAINS. IT IS STILL TOO EARLY
TO TELL IF THIS COLD AIR MASS WILL SETTLE INTO WEST TEXAS OR IF
WE/LL ONLY RECEIVE A GLANCING BLOW.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 28 9 29 9 37 / 10 10 10 10 10
TULIA 29 10 30 12 38 / 0 0 10 10 10
PLAINVIEW 31 11 31 11 38 / 10 10 10 10 10
LEVELLAND 34 11 32 12 38 / 10 10 10 10 10
LUBBOCK 33 12 33 13 39 / 10 10 0 10 10
DENVER CITY 36 13 32 12 38 / 10 10 10 10 10
BROWNFIELD 36 12 32 13 38 / 10 10 0 10 10
CHILDRESS 35 15 34 15 41 / 0 0 0 0 10
SPUR 35 14 34 15 40 / 0 0 0 0 10
ASPERMONT 37 16 36 14 41 / 0 0 10 0 10
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
29
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1106 AM CST SUN JAN 13 2013
.AVIATION...
NORTHWESTERLY WINDS AROUND 10 TO 20 KNOTS WILL CONTINUE FOR MOST
OF THE PERIOD...BECOMING NORTHERLY TOMORROW. MOSTLY CLEAR SKIES
WILL PREVAIL FOR MOST OF THE PERIOD...BUT SCT/BKN MID CLOUDS ARE
POSSIBLE TOMORROW AS A DISTURBANCE PASSES OVER NORTH TEXAS. NO
PRECIPITATION IS EXPECTED...DUE TO VERY DRY AIR IN THE LOWER
ATMOSPHERE.
HAMPSHIRE
&&
.PREV DISCUSSION... /ISSUED 425 AM CST SUN JAN 13 2013/
SHORT TERM WINTER WEATHER/FORECAST CONCERNS...
DID NOT MAKE ANY SIGNIFICANT CHANGES TO THE FORECAST FROM THE 139
AM CST FORECAST UPDATE/AFD. THERE IS STILL NO MODEL GUIDANCE THAT
HAS A GOOD HANDLE ON WINTRY PRECIPITATION FALLING NORTHWEST OF THE
METROPLEX EARLY THIS MORNING. THE HRRR IS CLOSEST...BUT DOESNT
SEEM TO KNOW WHAT IS CAUSING THE WINTRY PRECIPITATION. THE HRRR
CONSISTENTLY INITIALIZES THE RADAR RETURNS AND THEN ALLOWS THEM TO
DISSIPATE SHORTLY THEREAFTER WHICH IS A GOOD SIGN THAT THE MODEL
IS NOT RESOLVING THE FORCING MECHANISM THAT IS RESPONSIBLE FOR THE
PRESENCE OF THE PRECIPITATION. AT ANY RATE...DRAWING BACK ON
MORNING UPDATE DISCUSSIONS...THE GFS FORECAST THAT H700 CONFLUENCE
WOULD DISSIPATE EARLY THIS MORNING SEEMS TO BE SPOT ON ACCORDING
TO REGIONAL VWP OUTPUT. THE BEST H700 CONFLUENCE HAD MOVED NORTH
OF THE RED RIVER AS OF 09Z...AND LIGHT WINTRY PRECIPITATION WAS
LIFTING NORTHEAST AS WELL. THERE IS STILL SOME CONCERN FOR H800
FRONTOGENETIC FORCING ALONG A SHERMAN TO FORT WORTH TO GRANBURY
LINE AROUND SUNRISE RESULTING IN SOME SHALLOW CONVECTION
INITIATION. THE GFS CONTINUES TO ADVERTISE THIS FORCING FOR
ASCENT NEAR THE H800 LEVEL WITH A 100 MB LAYER ABOVE IT
CHARACTERIZED BY DECREASING THETA-E TEMPERATURES WITH
HEIGHT (ESSENTIALLY POSITIVE CAPE).
THAT SAID...THERE IS NO OBSERVATIONAL EVIDENCE THAT STRONG LIFT IS
OCCURRING AT THIS TIME AS THERE ARE NO RAPIDLY COOLING CLOUD TOPS
OR LIGHT MID-LEVEL RADAR REFLECTIVITY RETURNS OVER THESE AREAS AT
THE TIME OF THIS DISCUSSION. THEREFORE WILL NOT BE ISSUING A
FREEZING RAIN ADVISORY FROM SHERMAN...THROUGH THE DFW METROPLEX
AND SOUTHWEST TOWARDS GRANBURY AT THIS TIME. OF COURSE WE WILL
CONTINUE TO MONITOR THIS SITUATION CLOSELY THROUGH SUNRISE AS ANY
DEVELOPING PRECIPITATION WILL LIKELY BE COMPOSED OF SUPERCOOLED
WATER. WHILE THIS WOULD FALL IN LIQUID FORM...IT WOULD FREEZE
IMMEDIATELY UPON CONTACT WITH ANY SURFACE THAT IS ALSO AT OR BELOW
FREEZING. AT THIS TIME IT LOOKS AS THOUGH MOST PRECIPITATION
DEVELOPMENT WILL REMAIN SOUTHEAST OF THIS LINE THROUGH
SUNRISE...DIMINISHING THE THREAT FOR FREEZING RAIN OR SLEET.
TODAY THROUGH MONDAY...ALL GUIDANCE INDICATES THAT LOW-LEVEL
FRONTOGENETIC FORCING WILL DIMINISH IN INTENSITY THIS MORNING AS
DRY AIR AND SUBSIDENCE CONTINUE TO SLOWLY WORK INTO THE REGION.
DRY AIR NEAR THE SURFACE HAS ALREADY PENETRATED AS FAR SOUTHEAST
AS AN ATHENS TO TEMPLE LINE...BUT IT IS THE MOISTURE ALOFT THAT WE
HAVE TO WORRY ABOUT EARLY THIS MORNING. EXPECT ALL LIGHT RAIN/RAIN
SHOWERS TO MOVE EAST AFTER 18Z. DID KEEP IN A 20 PERCENT CHANCE
FOR A RAIN/SLEET MIX FOR LOCATIONS ALONG AND NORTH OF A
GAINESVILLE TO MCKINNEY TO COOPER LINE AFTER SUNRISE JUST IN CASE
THE H800 FRONTOGENESIS SCENARIO DESCRIBED ABOVE PANS OUT. THESE
LOCATIONS WOULD ALSO HAVE TO BE INCLUDED IN A BRIEF FREEZING RAIN
ADVISORY IF THIS PRECIPITATION DOES MANAGE TO DEVELOP AROUND/JUST
BEFORE SUNRISE. IF IT DOES NOT...THESE AREAS WILL LIKELY REMAIN
DRY THIS MORNING.
WE SHOULD SEE SOME SUNSHINE BY LATE THIS AFTERNOON...HOWEVER NOT
MUCH OF A WARM-UP IS EXPECTED TODAY AS NORTH WINDS AND MORNING
CLOUD COVER HELP TO KEEP TEMPERATURES IN THE LOWER TO MID 40S FOR
HIGHS FOR MOST LOCATIONS. FOR TONIGHT...ANOTHER STRONG SHORTWAVE
TROUGH IS EXPECTED TO MOVE OVER THE SOUTH PLAINS. THIS TROUGH WAS
OVER THE SOUTHERN CA COAST PER EARLY MORNING WATER VAPOR IMAGERY.
THIS TROUGH HAS A WELL-DEFINED CYCLONIC CIRCULATION IN WATER VAPOR
IMAGERY AND IS PROGGED TO SEND STRONG LARGE SCALE FORCING FOR
ASCENT OVER THE REGION AS IT MOVES NORTHEAST TONIGHT AND INTO
MONDAY MORNING.
FOR MOST OF NORTH TX...THIS STRONG FORCING FOR ASCENT IS EXPECTED
TO GO UNNOTICED AS DRY AIR AND SUBSIDENCE ARE EXPECTED TO HAVE
LEFT THE ATMOSPHERE RELATIVELY STABLE BY LATE TONIGHT.
HOWEVER...THE GFS/NAM/ECMWF ALL SHOW RELATIVELY STRONG AND
PERSISTENT ISENTROPIC LIFT ON THE 305 K SURFACE IN BETWEEN 06 AND
12Z MONDAY MORNING OVER THE FAR SOUTHEASTERN COUNTIES OF THE CWA.
MODELS DO NOT SHOW MUCH IN THE WAY OF QPF...HOWEVER MID-LEVEL
MOISTURE WILL LIKELY RESIDE NEAR THE GULF COAST BEFORE THIS TROUGH
MOVES OVER THE REGION TONIGHT. IT SEEMS REASONABLE THAT SOME OF
THIS MOISTURE WILL RETURN ON THE 305K SURFACE (NEAR THE H700 LEVEL
TONIGHT) AND RESULT IN SOME PERSISTENT MID-LEVEL PRECIPITATION
PRODUCTION BEFORE SUNRISE MONDAY.
THE LOWER TROPOSPHERE IS EXPECTED TO BE QUITE DRY BEFORE THIS
PROCESS STARTS...SO A SIGNIFICANT AMOUNT OF THIS MID-LEVEL
PRECIPITATION IS LIKELY TO EVAPORATE BEFORE REACHING THE GROUND.
REGARDLESS...CONFIDENCE IN THE MID-LEVEL PRECIPITATION PRODUCTION
IS HIGH...SO WENT AHEAD AND MENTIONED A 20 PERCENT CHANCE OF RAIN
OR FREEZING RAIN SOUTHEAST OF AN ATHENS TO TEMPLE LINE (NOT
INCLUDING WACO AT THIS TIME) FOR EARLY MONDAY MORNING. DO NOT
THINK THE IMPACTS OF THIS WILL BE HIGH UNLESS THE LOWER ATMOSPHERE
SATURATES QUICKER THAN EXPECTED. LIGHT PRECIPITATION WILL LIKELY
CONTINUE AFTER SUNRISE MONDAY MORNING FOR THESE
LOCATIONS...HOWEVER TEMPERATURES ARE LIKELY TO WARM ABOVE FREEZING
AFTER SUNRISE. WE MAY HAVE TO CONSIDER A WINTER WEATHER OR
FREEZING RAIN ADVISORY IF IT LOOKS LIKE MORE PRECIPITATION WILL
MAKE IT TO THE GROUND...BUT CONFIDENCE IS TOO LOW TO GO WITH
ANYTHING AT THIS TIME.
FOR MID-WEEK...THE ECMWF HAS COME MORE IN LINE WITH THE NAEFS
SOLUTION INDICATING THAT THE LONGWAVE TROUGH OVER THE WESTERN
THIRD OF THE CONUS WILL CONSOLIDATE AND MOVE EAST AS A POSITIVELY
TILTED TROUGH TUESDAY NIGHT INTO WEDNESDAY. THIS SOLUTION LIMITS
LARGE SCALE FORCING FOR ASCENT OVER NORTH AND CENTRAL TX BY
KEEPING LOW LEVEL FLOW VEERED AS IT MOVES OVER THE AREA. THIS
WOULD ALSO PREVENT ANY SIGNIFICANT MOISTURE FROM RETURNING TO THE
REGION OUT AHEAD OF THIS UPPER TROUGH. THE 00 AND 06Z NAM
SOLUTIONS BOTH PREFER THE STRONG AND SLOW MOVING CUT-OFF LOW
SOLUTION ADVERTISED BY THE ECMWF THE PAST FEW DAYS. WHILE THIS
SOLUTION IS AN OUTLIER SOLUTION...WE WILL CONTINUE TO WATCH FOR
ANY SIGN THAT THIS SOLUTION COULD VERIFY AS IT WOULD LIKELY ALLOW
FOR A SIGNIFICANT ICE STORM IN THE REGION IF IT VERIFIED. THIS
FORECAST CONTINUES TO SIDE WITH THE CONSENSUS OF THE NAEFS AND THE
13/00Z ECMWF AS THIS IS BY FAR THE MOST LIKELY OUTCOME. HOWEVER
WILL NOT COMPLETELY IGNORE THE NAM AS IT WOULD BRING A HIGH IMPACT
WINTER WEATHER EVENT TO SOME PART OF NORTH OR CENTRAL TX.
EXTENDED...ONCE THE LONGER WAVE TROUGH MOVES OUT OF THE
REGION...WE SHOULD SEE A SLOW WARMING TREND FOR THE REGION AS A
BLOCKING RIDGE SETS UP OVER THE WESTERN CONUS COAST KEEPING MORE
OR LESS NORTHWEST AND CONFLUENT FLOW OVER THE SOUTH PLAINS. THIS
WARM UP COULD COME TO AN ABRUPT END EARLY NEXT WEEK AS BOTH THE
GFS AND THE ECMWF HAVE A STRONG COLD FRONT MOVING SOUTH THROUGH
THE GREAT PLAINS. THE GFS COOLS US DOWN...BUT ALLOWS THE COLD AIR
TO MODIFY TO THE POINT THAT IT BEHAVES LIKE A TYPICAL WINTER COLD
FRONT FOR TEXAS. THAT IS WE COOL DOWN SIGNIFICANTLY...BUT
OVERNIGHT LOWS TEND TO SAY IN THE MID TO UPPER 20S WHILE HIGHS
CLIMB ABOVE FREEZING.
THE ECMWF BRINGS A SIGNIFICANT ARCTIC OUTBREAK SOUTH THROUGH THE
PLAINS...WHICH WOULD IMPACT NORTH TX SUNDAY NIGHT OR MONDAY IF IT
VERIFIED. THE 13/00Z ECMWF HAS A 1053 MB (MSLP) SURFACE HIGH
BARRELING SOUTH INTO THE CENTRAL PLAINS BEHIND THIS FRONT...WHICH
IS A SIGN OF A VERY COLD ARCTIC AIR INVASION OF THE PLAINS. THIS
IS NOT THE MOST LIKELY SOLUTION TO VERIFY AT THIS TIME...BUT IT
BEARS WATCHING AS WE GET CLOSER TO NEXT WEEKEND AND EARLY NEXT
WEEK. THE ECMWF WOULD BRING LOWS DOWN INTO THE TEENS IF NOT LOWER
ACROSS NORTH TX WHICH COULD CERTAINLY HAVE A BIG IMPACT ON THE
REGION. THIS IS SLIGHTLY BEYOND THE OFFICIAL FORECAST PERIOD AT
THIS TIME...SO WILL WATCH FOR MORE CONSISTENCY AMONGST MODELS
BEFORE JUMPING ON AN ARCTIC OUTBREAK TO START OFF THE NEXT WORK
WEEK.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 42 26 44 28 45 / 10 10 5 10 10
WACO, TX 45 27 43 27 45 / 10 10 10 10 10
PARIS, TX 41 25 44 26 43 / 30 10 10 10 10
DENTON, TX 42 24 43 23 45 / 10 10 5 10 10
MCKINNEY, TX 42 24 44 24 43 / 30 10 10 10 10
DALLAS, TX 42 27 44 29 44 / 10 10 10 10 10
TERRELL, TX 44 26 43 27 43 / 20 10 10 10 10
CORSICANA, TX 44 28 44 30 43 / 10 10 10 10 10
TEMPLE, TX 46 27 43 27 44 / 10 10 10 10 10
MINERAL WELLS, TX 42 22 43 22 44 / 5 10 5 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
85/85