Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/25/13
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
200 PM CST WED JAN 23 2013
.DISCUSSION...
1136 AM CST
A FOCUSED AREA OF SNOW HAS PERSISTED ALL MORNING AND IS NOW
EASING ITS WAY EASTWARD ACROSS NORTHERN IL. SNOWFALL AMOUNTS OF
OVER AN INCH ALONG WITH REMARKS OF LARGE SNOWFLAKES HAVE BEEN
OBSERVED IN A FEW PLACES ASSOCIATED WITH THIS. A NICE COMPACT AREA
OF MID TO UPPER LEVEL FORCING AT THE LEADING EDGE OF THE
NORTHWESTERLY JET MAXIMA HAS HELPED TO DRIVE THIS SNOW. ISENTROPIC
ASCENT AND MID-LEVEL CONVERGENCE AND FRONTOGENESIS ARE FORECAST BY
THE RAP AND NAM TO CONTINUE TO PUSH SLOWLY EAST AND WEAKEN
THROUGH THE AFTERNOON. WHILE THE DENDRITIC GROWTH ZONE REMAINS
DEEP FOR LARGER FLAKES...THE MOVEMENT OF THE FORCING AND BAND
SHOULD HELP TO FURTHER LIMIT ADDITIONAL ACCUMULATIONS. TO THE
NORTH ACROSS CHICAGO AND THE I-90 CORRIDOR...WIDESPREAD LIGHT
RADAR ECHOES ARE NOTED AND TEMPORARY LIGHT SNOW HAS BEEN REPORTED.
DO NOT SEE THIS CHANGING MUCH PRIOR TO THE COLD FRONT ARRIVING
NEAR SUNDOWN. FORECAST WINDS AND GUSTS HAVE BEEN INCREASED BY
AROUND 5 MPH FOR TONIGHT AS THE PRESSURE GRADIENT TIGHTENS
MARKEDLY BEHIND THE FRONT IN COINCIDENT WITH COLD AIR ADVECTION.
THIS WILL LEAD TO THE WIND CHILL AROUND -20 FOR A TIME LATE
TONIGHT AND EARLY THU MORNING ACROSS THE NORTHERN FORECAST AREA.
MTF
//PREV DISCUSSION...
410 AM CST
FORECAST FOCUS THIS MORNING IS ON POTENTIAL FOR LIGHT ACCUMULATING
SNOW TODAY...AS WELL AS A SECOND SYSTEM WHICH WILL LIKELY PRODUCE
SOME LIGHT SNOW ACROSS THE AREA AGAIN LATE THURSDAY NIGHT AND EARLY
FRIDAY. THE POTENTIAL ALSO EXISTS FOR SOME LAKE EFFECT SNOW TO WORK
ITS WAY INTO NORTHWEST INDIANA AND PERHAPS EVEN FAR NORTHEAST IL
LATER TONIGHT INTO THURSDAY.
FORECAST AREA REMAINS BENEATH FAST NORTHWEST FLOW ALOFT THIS
MORNING. SERIES OF WEAK IMPULSES CONTINUE TO RIPPLE SOUTHEAST ACROSS
THE NORTHERN PLAINS AND MIDWEST...WITH WATER VAPOR IMAGERY
INDICATING ONE SUCH SHEARED VORT DIVING SOUTHEAST ACROSS MN/IA
TOWARD THE FORECAST AREA. LOW LEVEL RESPONSE NOTED TO THE WEST...
WHERE LOW LEVEL WINDS HAVE BECOME SOUTHERLY...PRODUCING WARM
ADVECTION ACROSS AREAS WEST OF THE FORECAST AREA EARLY THIS MORNING.
REGIONAL RADAR COMPOSITE HAS SHOWN SOME WEAK BANDED RETURNS
DEVELOPING OVERNIGHT FROM SOUTHERN MINNESOTA INTO EASTERN IA...
WHICH CORRELATE FAIRLY WELL WITH WEAK MID-LEVEL FRONTOGENESIS
DEPICTED IN MODEL GUIDANCE. HIGH-RES MODELS INCLUDING THE WRF-NMM
SUGGEST THIS NORTHWEST-SOUTHEAST BANDED FRONTOGENETIC FORCING WILL
SLIDE SOUTHEAST INTO NORTHERN/CENTRAL ILLINOIS THIS MORNING...AND
WILL EVENTUALLY TRANSIT THE AREA THROUGH MID-AFTERNOON. THERE ARE
SOME LIMITING FACTORS AT WORK WITH RESPECT TO PRECIP/SNOW GENERATION
THIS MORNING...MAINLY THE DRY NATURE OF THE ARCTIC AIR MASS ACROSS
THE MIDWEST AND LACK OF STRONG MOISTURE ADVECTION. SHEARED NATURE OF
MID/UPPER LEVEL WAVE ALSO RESULTS IN LARGER SCALE VERTICAL MOTION IN
MID/UPPER LEVELS NOT NECESSARILY WELL-CORRELATED WITH THE LOWER
LEVEL F-GEN FORCING. THE EXPECTED TREND SHOULD BE FOR THESE
NORTHWEST-SOUTHWEST BANDS OF LIGHT SNOW TO CONTINUE TO DEVELOP AND
SPREAD EAST-SOUTHEASTWARD THIS MORNING...SETTING THE STAGE FOR A
FAIRLY HIGH PROBABILITY/LOW QPF PRECIP EVENT. MOST GUIDANCE ONLY
GENERATING A COUPLE HUNDREDTHS OF QPF AT BEST...THUS EVEN 20:1 SNOW
TO LIQUID RATIOS WITH SOUNDINGS INDICATING FAIRLY DEEP LAYER OF
FAVORABLE DENDRITIC GROWTH TEMPS SUGGEST AMOUNTS GENERALLY LESS THAN
AN INCH. FAVORED AXIS APPEARS TO BE FROM SOUTH OF ROCKFORD SOUTHEAST
THROUGH KANKAKEE OR SO...AND HAVE HIGHLIGHTED THIS CORRIDOR WITH
LIKELY POPS THROUGH EARLY AFTERNOON. BETTER F-GEN FORCING SLIDES
SOUTHEAST INTO INDIANA BY MID/LATE AFTERNOON...ALLOWING LIGHT SNOW
TO TAPER TO FLURRIES OR SCATTERED SNOW SHOWERS FROM THE NORTHWEST.
DEEPER MID-LEVEL TROUGH WHICH IS OVER WESTERN ONTARIO/MANITOBA THIS
MORNING WILL ALSO SHIFT SOUTHEAST ACROSS THE WESTERN GREAT LAKE
REGION LATER THIS AFTERNOON AND EVENING...THOUGH WITH ITS ASSOCIATED
SURFACE LOW PASSING NORTH OF THE FORECAST AREA...THEN MAIN EFFECT
SHOULD BE TO PUSH A COLD FRONT THROUGH THE AREA SETTING UP A RENEWED
PUSH OF LOW LEVEL COLD AIR AND A PERIOD OF BLUSTERY NORTH WINDS
TONIGHT. AS SURFACE HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...
LOW LEVEL WINDS VEERING MORE NORTH OVER LAKE MICHIGAN SHOULD SHIFT
FOCUS OF LAKE EFFECT SNOW BANDS FROM SOUTHWEST MICHIGAN...INTO
NORTHWEST AND NORTH CENTRAL INDIANA TONIGHT. LOCAL HIGH RES WRF
MODEL INDICATES LOW LEVEL CONVERGENT AXIS WILL SHIFT WEST INTO
PORTER AND EASTERN LAKE COUNTIES LATE TONIGHT INTO THURSDAY
MORNING...SETTING THE STAGE FOR ACCUMULATING LAKE EFFECT SNOW THERE.
WITH WINDS CONTINUING TO SHIFT TO THE NORTH THEN NORTHEAST AHEAD OF
THE APPROACHING SURFACE HIGH...THE BAND SHOULD MAINTAIN A STEADY
DRIFT WHICH WOULD HELP LIMIT SNOW AMOUNTS...THOUGH IT APPEARS THAT A
FEW INCHES MAY ACCUMULATE ACROSS NORTHERN PORTER/LAKE COUNTIES BY
THURSDAY MORNING. THE LAKE EFFECT BAND SHOULD CONTINUE TO SHIFT WEST
INTO EAST/SOUTHEAST COOK COUNTY DURING THE DAY THURSDAY...THOUGH
DECREASING WINDS AND LOWERING INVERSION HEIGHT SHOULD CAUSE IT TO
WEAKEN AS IT AFFECT CHICAGO. STILL...THE POTENTIAL FOR SOME
ACCUMULATION WILL EXIST EVEN ACROSS THE CITY AND SOUTHEAST SIDE.
FOR SYSTEM MOVING ACROSS THE UPPER MIDWEST THURSDAY/FRIDAY
MORNING...GUIDANCE HAS CONTINUED TO TREND TOWARD THE SCENARIO OF A
DOMINANT NORTHERN STREAM SHORT WAVE/SURFACE LOW COMBINATION...WHICH
TAKES THE BULK OF MEASURABLE PRECIP NORTH OF THE CWA LATE THURSDAY
NIGHT. QPF AMOUNTS OF GENERALLY LESS THAN 0.10 INCH WOULD INDICATE
ONLY LIGHT SNOW ACCUMULATIONS IN ISENTROPIC ASCENT IN WARM ADVECTION
REGION SOUTH OF THE LOW. CHILLY NORTH WINDS BEHIND THE DEPARTING
LOW/COLD FRONT FRIDAY AFTERNOON/EVENING MAY SUPPORT SOME FLURRIES OR
LIGHT SNOW SHOWERS...BUT NO SIGNIFICANT ACCUMS APPEAR IMMINENT.
HIGH PRESSURE THEN SPREADS ACROSS REGION AGAIN SATURDAY...WITH FLAT
UPPER RIDGING DEVELOPING ACROSS THE CENTRAL CONUS AS AN UPPER TROUGH
MOVES ACROSS THE WESTERN STATES. THIS SETS THE STAGE FOR WARMER
TEMPS...BUT ALSO THE POTENTIAL FOR A MIXED PRECIPITATION EVENT IN
THE SUNDAY-MONDAY TIME RANGE. WITH FORECAST SOUNDINGS INDICATING
WARM NOSE DEVELOPING ABOVE RETREATING SHALLOW ARCTIC AIR...A
SNOW/SLEET AND PERHAPS FREEZING RAIN SCENARIO IS POSSIBLE BEFORE
TEMPS WARM UP ENOUGH FOR RAIN AS WARM FRONT LIFTS NORTH TUESDAY.
WILL MENTION RAIN/SNOW/SLEET POTENTIAL...THOUGH MUCH CAN CHANGE BY
DAY 5-6.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LIGHT SNOW AND LOW VFR/HIGH MVFR CEILINGS/VIS THROUGH MID TO
LATE AFTERNOON.
* WEST/SOUTHWEST WINDS WITH SPORADIC GUSTS TO AROUND 16 KT
TODAY...THEN SHIFTING TO THE NORTHWEST AND INCREASING IN SPEED
THIS EVENING WITH PREVAILING GUSTS TO AROUND 35 KT THROUGH THE
EVENING.
KJB
//DISCUSSION...UPDATED 18Z...
THE MAIN CONCERNS WILL BE ANOTHER PERIOD OF LIGHT SNOW AND SNOW
SHOWERS THROUGH MID TO LATE AFTERNOON AND A PERIOD OF STRONG
NORTHWESTERLY WINDS THIS EVENING.
A MID LEVEL DISTURBANCE HAS RESULTED IN A BAND OF LIGHT SNOW ACROSS
PORTIONS OF NORTHERN ILLINOIS THROUGH THE MORNING HOURS. THE MAIN
BAND HAS REMAINED TO THE SOUTH AND WEST OF TERMINALS WITH ONLY SOME
OCCASIONAL FLURRIES ACROSS THE EASTERN TERMINALS. IT APPEARS THAT
THIS BAND OF LIGHT SNOW MAY BEGIN TO SHIFT EAST SOUTHEASTWARD
OVER THE NEXT FEW HOURS AS IT WEAKENS...POSSIBLY LEADING TO SOME
LOWER VISIBILITIES DOWN TO 2 TO 3 MILES IN LIGHT SNOW AFTER 19 UTC
THIS AFTERNOON AT THE EASTERN TERMINALS. CIGS COULD ALSO DROP
INTO THE MVFR CATEGORY...AROUND 2500 FEET FOR A PERIOD IN ANY
HEAVIER SNOW SHOWERS. ANY SNOW SHOWERS SHOULD ABATE LATER THIS
AFTERNOON.
THE OTHER CONCERN IS THROUGH THIS EVENING FROM ROUGHLY 01 UTC
THROUGH ABOUT 06 UTC. DURING THIS PERIOD A POTENT COLD FRONT IS
EXPECTED TO PUSH ACROSS THE AREA. THE COMBINATION OF A STRONGER PUSH
OF COLDER AIR AND RAPID PRESSURE RISES...IN ASSOCIATION WITH A 1040+
MB HIGH ACROSS THE UPPER MIDWEST...SHOULD RESULT IN A PERIOD OF
STRONG NORTHWESTERLY WINDS. CURRENTLY IT APPEARS WINDS COULD GUST UP
AROUND 35 KT FOR A FEW HOURS THIS EVENING...BEFORE THEY ABATE SOME
LATER TONIGHT.
DURING THE LATE MORNING AND INTO THE EARLY AFTERNOON ON THURSDAY
THERE COULD ALSO BE A PERIOD OF LAKE EFFECT SNOW SHOWERS ACROSS THE
FAR EASTERN TERMINALS. THE BEST POTENTIAL IS AT KGYY THURSDAY
MORNING. HOWEVER...KORD AND KMDW COULD GET A BRIEF PERIOD OF LIGHT
SNOW AS THE WIND FIELD QUICKLY SHIFTS OUT OF THE EAST-NORTHEAST BY
AFTERNOON AS THE SURFACE HIGH CONTINUES TO BUILD ACROSS WISCONSIN.
OVERALL THIS DOES NOT APPEAR TO BE A BIG LAKE EFFECT SNOW EVENT FOR
THE NORTHEASTERN ILLINOIS TERMINALS AS THE BAND OF SNOW SHOULD BE
WEAKENING. HOWEVER...THERE COULD BE A FEW HOUR PERIOD OF LOWER VIS
AND CIGS DURING THIS TIME.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE WITH LIGHT SNOW/LOWER VIS...ABATING AFTER 21 UTC.
* MEDIUM TO HIGH CONFIDENCE IN WINDS.
KJB
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...WIDESPREAD SNOW BECOMING LIKELY WITH POSSIBLE
MVFR/IFR.
FRIDAY...CHANCE LIGHT SNOW...POSSIBLE MVFR/IFR.
SATURDAY...VFR.
SUNDAY...CHANCE LIGHT SNOW...POSSIBLE MVFR/IFR.
MONDAY...CHANCE LIGHT SNOW...POSSIBLE MVFR/IFR.
TUESDAY...CHANCE LIGHT RAIN.
RODRIGUEZ
&&
.MARINE...
425 AM CST
WESTERLY WINDS ONGOING ACROSS THE LAKE THIS MORNING AS HIGH
PRESSURE IS SITUATED JUST TO THE SOUTH...AND A TROUGH OF LOW
PRESSURE IS SLIDING SOUTH ACROSS SOUTHERN ONTARIO AND THE NORTHERN
GREAT LAKES. THESE WESTERLY WINDS WILL REMAIN IN PLACE FOR MOST OF
THE DAY BEFORE A GRADUAL TRANSITION TO THE NORTHWEST OCCURS LATER
THIS AFTERNOON AS THIS LOW CONTINUES TO THE SOUTHEAST...WITH AN
INCREASE IN SPEEDS. EXPECT NORTHWEST WINDS OF 15 TO 25 KT TO
INCREASE TO 30 KT EARLY THIS EVENING BEFORE TURNING MORE NORTHERLY
ACROSS THE ENTIRE LAKE OVERNIGHT. ALTHOUGH PREVAILING GALE FORCE
WINDS ARE NOT ANTICIPATED OVERNIGHT TONIGHT...A BRIEF PERIOD
AROUND THE MIDNIGHT TIME FRAME OF SPORADIC GUSTS TO 35 KT WILL BE
POSSIBLE. WINDS WILL SLOWLY EASE THURSDAY MORNING AND THEN
CONTINUE DIMINISHING THROUGHOUT THE DAY AS HIGH PRESSURE MOVES
OVERHEAD. THEN EXPECT WINDS ACROSS THE ENTIRE LAKE TO PICK UP ONCE
AGAIN OUT OF THE SOUTH THURSDAY NIGHT INTO FRIDAY WITH THIS HIGH
DEPARTING...AND NEW LOW PRESSURE APPROACHING FROM THE WEST.
RODRIGUEZ
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...6 PM WEDNESDAY TO 4 PM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1151 AM CST WED JAN 23 2013
.DISCUSSION...
1136 AM CST
A FOCUSED AREA OF SNOW HAS PERSISTED ALL MORNING AND IS NOW
EASING ITS WAY EASTWARD ACROSS NORTHERN IL. SNOWFALL AMOUNTS OF
OVER AN INCH ALONG WITH REMARKS OF LARGE SNOWFLAKES HAVE BEEN
OBSERVED IN A FEW PLACES ASSOCIATED WITH THIS. A NICE COMPACT AREA
OF MID TO UPPER LEVEL FORCING AT THE LEADING EDGE OF THE
NORTHWESTERLY JET MAXIMA HAS HELPED TO DRIVE THIS SNOW. ISENTROPIC
ASCENT AND MID-LEVEL CONVERGENCE AND FRONTOGENESIS ARE FORECAST BY
THE RAP AND NAM TO CONTINUE TO PUSH SLOWLY EAST AND WEAKEN
THROUGH THE AFTERNOON. WHILE THE DENDRITIC GROWTH ZONE REMAINS
DEEP FOR LARGER FLAKES...THE MOVEMENT OF THE FORCING AND BAND
SHOULD HELP TO FURTHER LIMIT ADDITIONAL ACCUMULATIONS. TO THE
NORTH ACROSS CHICAGO AND THE I-90 CORRIDOR...WIDESPREAD LIGHT
RADAR ECHOES ARE NOTED AND TEMPORARY LIGHT SNOW HAS BEEN REPORTED.
DO NOT SEE THIS CHANGING MUCH PRIOR TO THE COLD FRONT ARRIVING
NEAR SUNDOWN. FORECAST WINDS AND GUSTS HAVE BEEN INCREASED BY
AROUND 5 MPH FOR TONIGHT AS THE PRESSURE GRADIENT TIGHTENS
MARKEDLY BEHIND THE FRONT IN COINCIDENT WITH COLD AIR ADVECTION.
THIS WILL LEAD TO THE WIND CHILL AROUND -20 FOR A TIME LATE
TONIGHT AND EARLY THU MORNING ACROSS THE NORTHERN FORECAST AREA.
MTF
//PREV DISCUSSION...
410 AM CST
FORECAST FOCUS THIS MORNING IS ON POTENTIAL FOR LIGHT ACCUMULATING
SNOW TODAY...AS WELL AS A SECOND SYSTEM WHICH WILL LIKELY PRODUCE
SOME LIGHT SNOW ACROSS THE AREA AGAIN LATE THURSDAY NIGHT AND EARLY
FRIDAY. THE POTENTIAL ALSO EXISTS FOR SOME LAKE EFFECT SNOW TO WORK
ITS WAY INTO NORTHWEST INDIANA AND PERHAPS EVEN FAR NORTHEAST IL
LATER TONIGHT INTO THURSDAY.
FORECAST AREA REMAINS BENEATH FAST NORTHWEST FLOW ALOFT THIS
MORNING. SERIES OF WEAK IMPULSES CONTINUE TO RIPPLE SOUTHEAST ACROSS
THE NORTHERN PLAINS AND MIDWEST...WITH WATER VAPOR IMAGERY
INDICATING ONE SUCH SHEARED VORT DIVING SOUTHEAST ACROSS MN/IA
TOWARD THE FORECAST AREA. LOW LEVEL RESPONSE NOTED TO THE WEST...
WHERE LOW LEVEL WINDS HAVE BECOME SOUTHERLY...PRODUCING WARM
ADVECTION ACROSS AREAS WEST OF THE FORECAST AREA EARLY THIS MORNING.
REGIONAL RADAR COMPOSITE HAS SHOWN SOME WEAK BANDED RETURNS
DEVELOPING OVERNIGHT FROM SOUTHERN MINNESOTA INTO EASTERN IA...
WHICH CORRELATE FAIRLY WELL WITH WEAK MID-LEVEL FRONTOGENESIS
DEPICTED IN MODEL GUIDANCE. HIGH-RES MODELS INCLUDING THE WRF-NMM
SUGGEST THIS NORTHWEST-SOUTHEAST BANDED FRONTOGENETIC FORCING WILL
SLIDE SOUTHEAST INTO NORTHERN/CENTRAL ILLINOIS THIS MORNING...AND
WILL EVENTUALLY TRANSIT THE AREA THROUGH MID-AFTERNOON. THERE ARE
SOME LIMITING FACTORS AT WORK WITH RESPECT TO PRECIP/SNOW GENERATION
THIS MORNING...MAINLY THE DRY NATURE OF THE ARCTIC AIR MASS ACROSS
THE MIDWEST AND LACK OF STRONG MOISTURE ADVECTION. SHEARED NATURE OF
MID/UPPER LEVEL WAVE ALSO RESULTS IN LARGER SCALE VERTICAL MOTION IN
MID/UPPER LEVELS NOT NECESSARILY WELL-CORRELATED WITH THE LOWER
LEVEL F-GEN FORCING. THE EXPECTED TREND SHOULD BE FOR THESE
NORTHWEST-SOUTHWEST BANDS OF LIGHT SNOW TO CONTINUE TO DEVELOP AND
SPREAD EAST-SOUTHEASTWARD THIS MORNING...SETTING THE STAGE FOR A
FAIRLY HIGH PROBABILITY/LOW QPF PRECIP EVENT. MOST GUIDANCE ONLY
GENERATING A COUPLE HUNDREDTHS OF QPF AT BEST...THUS EVEN 20:1 SNOW
TO LIQUID RATIOS WITH SOUNDINGS INDICATING FAIRLY DEEP LAYER OF
FAVORABLE DENDRITIC GROWTH TEMPS SUGGEST AMOUNTS GENERALLY LESS THAN
AN INCH. FAVORED AXIS APPEARS TO BE FROM SOUTH OF ROCKFORD SOUTHEAST
THROUGH KANKAKEE OR SO...AND HAVE HIGHLIGHTED THIS CORRIDOR WITH
LIKELY POPS THROUGH EARLY AFTERNOON. BETTER F-GEN FORCING SLIDES
SOUTHEAST INTO INDIANA BY MID/LATE AFTERNOON...ALLOWING LIGHT SNOW
TO TAPER TO FLURRIES OR SCATTERED SNOW SHOWERS FROM THE NORTHWEST.
DEEPER MID-LEVEL TROUGH WHICH IS OVER WESTERN ONTARIO/MANITOBA THIS
MORNING WILL ALSO SHIFT SOUTHEAST ACROSS THE WESTERN GREAT LAKE
REGION LATER THIS AFTERNOON AND EVENING...THOUGH WITH ITS ASSOCIATED
SURFACE LOW PASSING NORTH OF THE FORECAST AREA...THEN MAIN EFFECT
SHOULD BE TO PUSH A COLD FRONT THROUGH THE AREA SETTING UP A RENEWED
PUSH OF LOW LEVEL COLD AIR AND A PERIOD OF BLUSTERY NORTH WINDS
TONIGHT. AS SURFACE HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...
LOW LEVEL WINDS VEERING MORE NORTH OVER LAKE MICHIGAN SHOULD SHIFT
FOCUS OF LAKE EFFECT SNOW BANDS FROM SOUTHWEST MICHIGAN...INTO
NORTHWEST AND NORTH CENTRAL INDIANA TONIGHT. LOCAL HIGH RES WRF
MODEL INDICATES LOW LEVEL CONVERGENT AXIS WILL SHIFT WEST INTO
PORTER AND EASTERN LAKE COUNTIES LATE TONIGHT INTO THURSDAY
MORNING...SETTING THE STAGE FOR ACCUMULATING LAKE EFFECT SNOW THERE.
WITH WINDS CONTINUING TO SHIFT TO THE NORTH THEN NORTHEAST AHEAD OF
THE APPROACHING SURFACE HIGH...THE BAND SHOULD MAINTAIN A STEADY
DRIFT WHICH WOULD HELP LIMIT SNOW AMOUNTS...THOUGH IT APPEARS THAT A
FEW INCHES MAY ACCUMULATE ACROSS NORTHERN PORTER/LAKE COUNTIES BY
THURSDAY MORNING. THE LAKE EFFECT BAND SHOULD CONTINUE TO SHIFT WEST
INTO EAST/SOUTHEAST COOK COUNTY DURING THE DAY THURSDAY...THOUGH
DECREASING WINDS AND LOWERING INVERSION HEIGHT SHOULD CAUSE IT TO
WEAKEN AS IT AFFECT CHICAGO. STILL...THE POTENTIAL FOR SOME
ACCUMULATION WILL EXIST EVEN ACROSS THE CITY AND SOUTHEAST SIDE.
FOR SYSTEM MOVING ACROSS THE UPPER MIDWEST THURSDAY/FRIDAY
MORNING...GUIDANCE HAS CONTINUED TO TREND TOWARD THE SCENARIO OF A
DOMINANT NORTHERN STREAM SHORT WAVE/SURFACE LOW COMBINATION...WHICH
TAKES THE BULK OF MEASURABLE PRECIP NORTH OF THE CWA LATE THURSDAY
NIGHT. QPF AMOUNTS OF GENERALLY LESS THAN 0.10 INCH WOULD INDICATE
ONLY LIGHT SNOW ACCUMULATIONS IN ISENTROPIC ASCENT IN WARM ADVECTION
REGION SOUTH OF THE LOW. CHILLY NORTH WINDS BEHIND THE DEPARTING
LOW/COLD FRONT FRIDAY AFTERNOON/EVENING MAY SUPPORT SOME FLURRIES OR
LIGHT SNOW SHOWERS...BUT NO SIGNIFICANT ACCUMS APPEAR IMMINENT.
HIGH PRESSURE THEN SPREADS ACROSS REGION AGAIN SATURDAY...WITH FLAT
UPPER RIDGING DEVELOPING ACROSS THE CENTRAL CONUS AS AN UPPER TROUGH
MOVES ACROSS THE WESTERN STATES. THIS SETS THE STAGE FOR WARMER
TEMPS...BUT ALSO THE POTENTIAL FOR A MIXED PRECIPITATION EVENT IN
THE SUNDAY-MONDAY TIME RANGE. WITH FORECAST SOUNDINGS INDICATING
WARM NOSE DEVELOPING ABOVE RETREATING SHALLOW ARCTIC AIR...A
SNOW/SLEET AND PERHAPS FREEZING RAIN SCENARIO IS POSSIBLE BEFORE
TEMPS WARM UP ENOUGH FOR RAIN AS WARM FRONT LIFTS NORTH TUESDAY.
WILL MENTION RAIN/SNOW/SLEET POTENTIAL...THOUGH MUCH CAN CHANGE BY
DAY 5-6.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LIGHT SNOW AND LOW VFR/HIGH MVFR CEILINGS/VIS THROUGH MID TO
LATE AFTERNOON.
* WEST/SOUTHWEST WINDS WITH SPORADIC GUSTS TO AROUND 16 KT
TODAY...THEN SHIFTING TO THE NORTHWEST AND INCREASING IN SPEED
THIS EVENING WITH PREVAILING GUSTS TO AROUND 35 KT THROUGH THE
EVENING.
KJB
//DISCUSSION...UPDATED 18Z...
THE MAIN CONCERNS WILL BE ANOTHER PERIOD OF LIGHT SNOW AND SNOW
SHOWERS THROUGH MID TO LATE AFTERNOON AND A PERIOD OF STRONG
NORTHWESTERLY WINDS THIS EVENING.
A MID LEVEL DISTURBANCE HAS RESULTED IN A BAND OF LIGHT SNOW ACROSS
PORTIONS OF NORTHERN ILLINOIS THROUGH THE MORNING HOURS. THE MAIN
BAND HAS REMAINED TO THE SOUTH AND WEST OF TERMINALS WITH ONLY SOME
OCCASIONAL FLURRIES ACROSS THE EASTERN TERMINALS. IT APPEARS THAT
THIS BAND OF LIGHT SNOW MAY BEGIN TO SHIFT EAST SOUTHEASTWARD
OVER THE NEXT FEW HOURS AS IT WEAKENS...POSSIBLY LEADING TO SOME
LOWER VISIBILITIES DOWN TO 2 TO 3 MILES IN LIGHT SNOW AFTER 19 UTC
THIS AFTERNOON AT THE EASTERN TERMINALS. CIGS COULD ALSO DROP
INTO THE MVFR CATEGORY...AROUND 2500 FEET FOR A PERIOD IN ANY
HEAVIER SNOW SHOWERS. ANY SNOW SHOWERS SHOULD ABATE LATER THIS
AFTERNOON.
THE OTHER CONCERN IS THROUGH THIS EVENING FROM ROUGHLY 01 UTC
THROUGH ABOUT 06 UTC. DURING THIS PERIOD A POTENT COLD FRONT IS
EXPECTED TO PUSH ACROSS THE AREA. THE COMBINATION OF A STRONGER PUSH
OF COLDER AIR AND RAPID PRESSURE RISES...IN ASSOCIATION WITH A 1040+
MB HIGH ACROSS THE UPPER MIDWEST...SHOULD RESULT IN A PERIOD OF
STRONG NORTHWESTERLY WINDS. CURRENTLY IT APPEARS WINDS COULD GUST UP
AROUND 35 KT FOR A FEW HOURS THIS EVENING...BEFORE THEY ABATE SOME
LATER TONIGHT.
DURING THE LATE MORNING AND INTO THE EARLY AFTERNOON ON THURSDAY
THERE COULD ALSO BE A PERIOD OF LAKE EFFECT SNOW SHOWERS ACROSS THE
FAR EASTERN TERMINALS. THE BEST POTENTIAL IS AT KGYY THURSDAY
MORNING. HOWEVER...KORD AND KMDW COULD GET A BRIEF PERIOD OF LIGHT
SNOW AS THE WIND FIELD QUICKLY SHIFTS OUT OF THE EAST-NORTHEAST BY
AFTERNOON AS THE SURFACE HIGH CONTINUES TO BUILD ACROSS WISCONSIN.
OVERALL THIS DOES NOT APPEAR TO BE A BIG LAKE EFFECT SNOW EVENT FOR
THE NORTHEASTERN ILLINOIS TERMINALS AS THE BAND OF SNOW SHOULD BE
WEAKENING. HOWEVER...THERE COULD BE A FEW HOUR PERIOD OF LOWER VIS
AND CIGS DURING THIS TIME.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE WITH LIGHT SNOW/LOWER VIS/LOWER CEILINGS...BUT
LOW CONFIDENCE ON EXACT TIMING.
* MEDIUM TO HIGH CONFIDENCE IN WINDS.
KJB
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...WIDESPREAD SNOW BECOMING LIKELY WITH POSSIBLE
MVFR/IFR.
FRIDAY...CHANCE LIGHT SNOW...POSSIBLE MVFR/IFR.
SATURDAY...VFR.
SUNDAY...CHANCE LIGHT SNOW...POSSIBLE MVFR/IFR.
MONDAY...CHANCE LIGHT SNOW...POSSIBLE MVFR/IFR.
TUESDAY...CHANCE LIGHT RAIN.
RODRIGUEZ
&&
.MARINE...
425 AM CST
WESTERLY WINDS ONGOING ACROSS THE LAKE THIS MORNING AS HIGH
PRESSURE IS SITUATED JUST TO THE SOUTH...AND A TROUGH OF LOW
PRESSURE IS SLIDING SOUTH ACROSS SOUTHERN ONTARIO AND THE NORTHERN
GREAT LAKES. THESE WESTERLY WINDS WILL REMAIN IN PLACE FOR MOST OF
THE DAY BEFORE A GRADUAL TRANSITION TO THE NORTHWEST OCCURS LATER
THIS AFTERNOON AS THIS LOW CONTINUES TO THE SOUTHEAST...WITH AN
INCREASE IN SPEEDS. EXPECT NORTHWEST WINDS OF 15 TO 25 KT TO
INCREASE TO 30 KT EARLY THIS EVENING BEFORE TURNING MORE NORTHERLY
ACROSS THE ENTIRE LAKE OVERNIGHT. ALTHOUGH PREVAILING GALE FORCE
WINDS ARE NOT ANTICIPATED OVERNIGHT TONIGHT...A BRIEF PERIOD
AROUND THE MIDNIGHT TIME FRAME OF SPORADIC GUSTS TO 35 KT WILL BE
POSSIBLE. WINDS WILL SLOWLY EASE THURSDAY MORNING AND THEN
CONTINUE DIMINISHING THROUGHOUT THE DAY AS HIGH PRESSURE MOVES
OVERHEAD. THEN EXPECT WINDS ACROSS THE ENTIRE LAKE TO PICK UP ONCE
AGAIN OUT OF THE SOUTH THURSDAY NIGHT INTO FRIDAY WITH THIS HIGH
DEPARTING...AND NEW LOW PRESSURE APPROACHING FROM THE WEST.
RODRIGUEZ
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...6 PM WEDNESDAY TO 4 PM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
1138 AM CST WED JAN 23 2013
.DISCUSSION...
1136 AM CST
A FOCUSED AREA OF SNOW HAS PERSISTED ALL MORNING AND IS NOW
EASING ITS WAY EASTWARD ACROSS NORTHERN IL. SNOWFALL AMOUNTS OF
OVER AN INCH ALONG WITH REMARKS OF LARGE SNOWFLAKES HAVE BEEN
OBSERVED IN A FEW PLACES ASSOCIATED WITH THIS. A NICE COMPACT AREA
OF MID TO UPPER LEVEL FORCING AT THE LEADING EDGE OF THE
NORTHWESTERLY JET MAXIMA HAS HELPED TO DRIVE THIS SNOW. ISENTROPIC
ASCENT AND MID-LEVEL CONVERGENCE AND FRONTOGENESIS ARE FORECAST BY
THE RAP AND NAM TO CONTINUE TO PUSH SLOWLY EAST AND WEAKEN
THROUGH THE AFTERNOON. WHILE THE DENDRITIC GROWTH ZONE REMAINS
DEEP FOR LARGER FLAKES...THE MOVEMENT OF THE FORCING AND BAND
SHOULD HELP TO FURTHER LIMIT ADDITIONAL ACCUMULATIONS. TO THE
NORTH ACROSS CHICAGO AND THE I-90 CORRIDOR...WIDESPREAD LIGHT
RADAR ECHOES ARE NOTED AND TEMPORARY LIGHT SNOW HAS BEEN REPORTED.
DO NOT SEE THIS CHANGING MUCH PRIOR TO THE COLD FRONT ARRIVING
NEAR SUNDOWN. FORECAST WINDS AND GUSTS HAVE BEEN INCREASED BY
AROUND 5 MPH FOR TONIGHT AS THE PRESSURE GRADIENT TIGHTENS
MARKEDLY BEHIND THE FRONT IN COINCIDENT WITH COLD AIR ADVECTION.
THIS WILL LEAD TO THE WIND CHILL AROUND -20 FOR A TIME LATE
TONIGHT AND EARLY THU MORNING ACROSS THE NORTHERN FORECAST AREA.
MTF
&&
.PREV DISCUSSION...
410 AM CST
FORECAST FOCUS THIS MORNING IS ON POTENTIAL FOR LIGHT ACCUMULATING
SNOW TODAY...AS WELL AS A SECOND SYSTEM WHICH WILL LIKELY PRODUCE
SOME LIGHT SNOW ACROSS THE AREA AGAIN LATE THURSDAY NIGHT AND EARLY
FRIDAY. THE POTENTIAL ALSO EXISTS FOR SOME LAKE EFFECT SNOW TO WORK
ITS WAY INTO NORTHWEST INDIANA AND PERHAPS EVEN FAR NORTHEAST IL
LATER TONIGHT INTO THURSDAY.
FORECAST AREA REMAINS BENEATH FAST NORTHWEST FLOW ALOFT THIS
MORNING. SERIES OF WEAK IMPULSES CONTINUE TO RIPPLE SOUTHEAST ACROSS
THE NORTHERN PLAINS AND MIDWEST...WITH WATER VAPOR IMAGERY
INDICATING ONE SUCH SHEARED VORT DIVING SOUTHEAST ACROSS MN/IA
TOWARD THE FORECAST AREA. LOW LEVEL RESPONSE NOTED TO THE WEST...
WHERE LOW LEVEL WINDS HAVE BECOME SOUTHERLY...PRODUCING WARM
ADVECTION ACROSS AREAS WEST OF THE FORECAST AREA EARLY THIS MORNING.
REGIONAL RADAR COMPOSITE HAS SHOWN SOME WEAK BANDED RETURNS
DEVELOPING OVERNIGHT FROM SOUTHERN MINNESOTA INTO EASTERN IA...
WHICH CORRELATE FAIRLY WELL WITH WEAK MID-LEVEL FRONTOGENESIS
DEPICTED IN MODEL GUIDANCE. HIGH-RES MODELS INCLUDING THE WRF-NMM
SUGGEST THIS NORTHWEST-SOUTHEAST BANDED FRONTOGENETIC FORCING WILL
SLIDE SOUTHEAST INTO NORTHERN/CENTRAL ILLINOIS THIS MORNING...AND
WILL EVENTUALLY TRANSIT THE AREA THROUGH MID-AFTERNOON. THERE ARE
SOME LIMITING FACTORS AT WORK WITH RESPECT TO PRECIP/SNOW GENERATION
THIS MORNING...MAINLY THE DRY NATURE OF THE ARCTIC AIR MASS ACROSS
THE MIDWEST AND LACK OF STRONG MOISTURE ADVECTION. SHEARED NATURE OF
MID/UPPER LEVEL WAVE ALSO RESULTS IN LARGER SCALE VERTICAL MOTION IN
MID/UPPER LEVELS NOT NECESSARILY WELL-CORRELATED WITH THE LOWER
LEVEL F-GEN FORCING. THE EXPECTED TREND SHOULD BE FOR THESE
NORTHWEST-SOUTHWEST BANDS OF LIGHT SNOW TO CONTINUE TO DEVELOP AND
SPREAD EAST-SOUTHEASTWARD THIS MORNING...SETTING THE STAGE FOR A
FAIRLY HIGH PROBABILITY/LOW QPF PRECIP EVENT. MOST GUIDANCE ONLY
GENERATING A COUPLE HUNDREDTHS OF QPF AT BEST...THUS EVEN 20:1 SNOW
TO LIQUID RATIOS WITH SOUNDINGS INDICATING FAIRLY DEEP LAYER OF
FAVORABLE DENDRITIC GROWTH TEMPS SUGGEST AMOUNTS GENERALLY LESS THAN
AN INCH. FAVORED AXIS APPEARS TO BE FROM SOUTH OF ROCKFORD SOUTHEAST
THROUGH KANKAKEE OR SO...AND HAVE HIGHLIGHTED THIS CORRIDOR WITH
LIKELY POPS THROUGH EARLY AFTERNOON. BETTER F-GEN FORCING SLIDES
SOUTHEAST INTO INDIANA BY MID/LATE AFTERNOON...ALLOWING LIGHT SNOW
TO TAPER TO FLURRIES OR SCATTERED SNOW SHOWERS FROM THE NORTHWEST.
DEEPER MID-LEVEL TROUGH WHICH IS OVER WESTERN ONTARIO/MANITOBA THIS
MORNING WILL ALSO SHIFT SOUTHEAST ACROSS THE WESTERN GREAT LAKE
REGION LATER THIS AFTERNOON AND EVENING...THOUGH WITH ITS ASSOCIATED
SURFACE LOW PASSING NORTH OF THE FORECAST AREA...THEN MAIN EFFECT
SHOULD BE TO PUSH A COLD FRONT THROUGH THE AREA SETTING UP A RENEWED
PUSH OF LOW LEVEL COLD AIR AND A PERIOD OF BLUSTERY NORTH WINDS
TONIGHT. AS SURFACE HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...
LOW LEVEL WINDS VEERING MORE NORTH OVER LAKE MICHIGAN SHOULD SHIFT
FOCUS OF LAKE EFFECT SNOW BANDS FROM SOUTHWEST MICHIGAN...INTO
NORTHWEST AND NORTH CENTRAL INDIANA TONIGHT. LOCAL HIGH RES WRF
MODEL INDICATES LOW LEVEL CONVERGENT AXIS WILL SHIFT WEST INTO
PORTER AND EASTERN LAKE COUNTIES LATE TONIGHT INTO THURSDAY
MORNING...SETTING THE STAGE FOR ACCUMULATING LAKE EFFECT SNOW THERE.
WITH WINDS CONTINUING TO SHIFT TO THE NORTH THEN NORTHEAST AHEAD OF
THE APPROACHING SURFACE HIGH...THE BAND SHOULD MAINTAIN A STEADY
DRIFT WHICH WOULD HELP LIMIT SNOW AMOUNTS...THOUGH IT APPEARS THAT A
FEW INCHES MAY ACCUMULATE ACROSS NORTHERN PORTER/LAKE COUNTIES BY
THURSDAY MORNING. THE LAKE EFFECT BAND SHOULD CONTINUE TO SHIFT WEST
INTO EAST/SOUTHEAST COOK COUNTY DURING THE DAY THURSDAY...THOUGH
DECREASING WINDS AND LOWERING INVERSION HEIGHT SHOULD CAUSE IT TO
WEAKEN AS IT AFFECT CHICAGO. STILL...THE POTENTIAL FOR SOME
ACCUMULATION WILL EXIST EVEN ACROSS THE CITY AND SOUTHEAST SIDE.
FOR SYSTEM MOVING ACROSS THE UPPER MIDWEST THURSDAY/FRIDAY
MORNING...GUIDANCE HAS CONTINUED TO TREND TOWARD THE SCENARIO OF A
DOMINANT NORTHERN STREAM SHORT WAVE/SURFACE LOW COMBINATION...WHICH
TAKES THE BULK OF MEASURABLE PRECIP NORTH OF THE CWA LATE THURSDAY
NIGHT. QPF AMOUNTS OF GENERALLY LESS THAN 0.10 INCH WOULD INDICATE
ONLY LIGHT SNOW ACCUMULATIONS IN ISENTROPIC ASCENT IN WARM ADVECTION
REGION SOUTH OF THE LOW. CHILLY NORTH WINDS BEHIND THE DEPARTING
LOW/COLD FRONT FRIDAY AFTERNOON/EVENING MAY SUPPORT SOME FLURRIES OR
LIGHT SNOW SHOWERS...BUT NO SIGNIFICANT ACCUMS APPEAR IMMINENT.
HIGH PRESSURE THEN SPREADS ACROSS REGION AGAIN SATURDAY...WITH FLAT
UPPER RIDGING DEVELOPING ACROSS THE CENTRAL CONUS AS AN UPPER TROUGH
MOVES ACROSS THE WESTERN STATES. THIS SETS THE STAGE FOR WARMER
TEMPS...BUT ALSO THE POTENTIAL FOR A MIXED PRECIPITATION EVENT IN
THE SUNDAY-MONDAY TIME RANGE. WITH FORECAST SOUNDINGS INDICATING
WARM NOSE DEVELOPING ABOVE RETREATING SHALLOW ARCTIC AIR...A
SNOW/SLEET AND PERHAPS FREEZING RAIN SCENARIO IS POSSIBLE BEFORE
TEMPS WARM UP ENOUGH FOR RAIN AS WARM FRONT LIFTS NORTH TUESDAY.
WILL MENTION RAIN/SNOW/SLEET POTENTIAL...THOUGH MUCH CAN CHANGE BY
DAY 5-6.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* LIGHT SNOW AND LOW VFR/HIGH MVFR CEILINGS/VIS TODAY.
* WEST/SOUTHWEST WINDS WITH SPORADIC GUSTS TO AROUND 16 KT
TODAY...THEN SHIFTING TO THE NORTHWEST AND INCREASING IN SPEED
THIS EVENING WITH PREVAILING GUSTS TO AROUND 35 KT THROUGH THE
EVENING.
RODRIGUEZ/KB
//DISCUSSION...UPDATED 14Z...
THE UPDATE CONSISTED OF SOME MINOR TWEAKS TO THE SNOWFALL
FORECAST LATER THIS MORNING. IT APPEARS THE MAIN CORRIDOR OF
FORCING WILL KEEP THE BETTER SNOWFALL TO THE WEST AND SOUTH OF THE
TERMINALS...WITH ONLY SOME LIGHT SNOW AND FLURRIES EXPECTED ACROSS
THE EASTERN TERMINALS. AS A CONSEQUENCE OF THIS...I BACKED OFF
SLIGHTLY ON THE GOING TEMPO TO MENTION ONLY LOW END MVFR VIS.
THE OTHER CHANGE WAS TO INCREASE WIND SPEEDS THIS EVENING. A COLD
FRONT WILL PUSH ACROSS THE AREA BY EARLY EVENING AND WITH STRONG
HIGH PRESSURE QUICKLY BUILDING IN BEHIND IT...EXPECT NORTHWEST
WINDS TO GUST UP TO 30-35 KT THROUGH THE EVENING.
//DISCUSSION...UPDATED 12Z...
LIGHT SNOW CONTINUES TO DEVELOP AND SPREAD SOUTHEAST ACROSS THE
REGION THIS MORNING WITH SOME LIGHT RETURNS SHOWING UP ON
RADAR...BUT WITH SNOW NOT BEING REPORTED ACROSS THE AREA AT THIS
TIME. SOME DRIER AIR WILL FIRST HAVE TO BE OVERCOME...WHICH WILL
LIKELY OCCUR OVER THE NEXT COUPLE OF HOURS. AM EXPECTING A DELAY
TO THE ONSET OF THIS SNOW DUE TO THIS DRIER AIR...BUT IF THE
COLUMN WERE TO SATURATE QUICKER...LIGHT SNOW COULD POSSIBLY OCCUR
SLIGHTLY EARLIER. WITH THIS SATURATION...VFR CEILINGS SHOULD FALL
BUT REMAIN VFR. VFR CEILINGS ARE EXPECTED BUT WITH PERIODS OF MVFR
CEILINGS AROUND 2500FT EXPECTED TODAY...AS VIS COULD FALL AS LOW
AS 2SM AT TIMES. EXPECT THIS SNOW TO SHIFT SOUTHEAST OF THE
TERMINALS EARLY THIS AFTERNOON WITH ONLY FLURRIES EXPECTED...WITH
PREVAILING VFR CEILINGS FOR THE REMAINDER OF THE EVENING BEFORE
SCATTERING LATER TONIGHT.
LIGHT WEST/SOUTHWEST WINDS WILL OCCUR TODAY WITH SOME SPORADIC
GUSTS POSSIBLE. THEN LATER THIS EVENING EXPECT WINDS TO TURN MORE
TO THE NORTHWEST AND INCREASE...AND WITH GUSTS AROUND 22KT
POSSIBLE OVERNIGHT.
RODRIGUEZ
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE WITH LIGHT SNOW/LOWER VIS/LOWER CEILINGS...BUT
LOW CONFIDENCE ON EXACT TIMING.
* MEDIUM TO HIGH CONFIDENCE IN WINDS.
RODRIGUEZ/KB
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...WIDESPREAD SNOW BECOMING LIKELY WITH POSSIBLE
MVFR/IFR.
FRIDAY...CHANCE LIGHT SNOW...POSSIBLE MVFR/IFR.
SATURDAY...VFR.
SUNDAY...CHANCE LIGHT SNOW...POSSIBLE MVFR/IFR.
MONDAY...CHANCE LIGHT SNOW...POSSIBLE MVFR/IFR.
TUESDAY...CHANCE LIGHT RAIN.
RODRIGUEZ
&&
.MARINE...
425 AM CST
WESTERLY WINDS ONGOING ACROSS THE LAKE THIS MORNING AS HIGH
PRESSURE IS SITUATED JUST TO THE SOUTH...AND A TROUGH OF LOW
PRESSURE IS SLIDING SOUTH ACROSS SOUTHERN ONTARIO AND THE NORTHERN
GREAT LAKES. THESE WESTERLY WINDS WILL REMAIN IN PLACE FOR MOST OF
THE DAY BEFORE A GRADUAL TRANSITION TO THE NORTHWEST OCCURS LATER
THIS AFTERNOON AS THIS LOW CONTINUES TO THE SOUTHEAST...WITH AN
INCREASE IN SPEEDS. EXPECT NORTHWEST WINDS OF 15 TO 25 KT TO
INCREASE TO 30 KT EARLY THIS EVENING BEFORE TURNING MORE NORTHERLY
ACROSS THE ENTIRE LAKE OVERNIGHT. ALTHOUGH PREVAILING GALE FORCE
WINDS ARE NOT ANTICIPATED OVERNIGHT TONIGHT...A BRIEF PERIOD
AROUND THE MIDNIGHT TIME FRAME OF SPORADIC GUSTS TO 35 KT WILL BE
POSSIBLE. WINDS WILL SLOWLY EASE THURSDAY MORNING AND THEN
CONTINUE DIMINISHING THROUGHOUT THE DAY AS HIGH PRESSURE MOVES
OVERHEAD. THEN EXPECT WINDS ACROSS THE ENTIRE LAKE TO PICK UP ONCE
AGAIN OUT OF THE SOUTH THURSDAY NIGHT INTO FRIDAY WITH THIS HIGH
DEPARTING...AND NEW LOW PRESSURE APPROACHING FROM THE WEST.
RODRIGUEZ
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...6 PM WEDNESDAY TO 4 PM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
621 PM CST THU JAN 24 2013
.SHORT TERM...
ISSUED AT 334 PM CST THU JAN 24 2013
(TONIGHT)
THE MAIN ISSUE FOR TONIGHT IS WHETHER OR NOT WE WILL SEE SOME LIGHT
WINTRY PRECIPITATION. THE OVERALL SYNOPTIC SCENARIO APPEARS
UNCHANGED. AN EXPANSIVE COLD HIGH PRESSURE SYSTEM CURRENTLY CENTERED
THRU THE WRN GREAT LAKES WILL RETREAT EASTWARD THRU THE OH VALLEY
AND INTO THE EASTERN U.S. BY DAYBREAK FRIDAY. IN THE PROCESS...LOW
LEVEL FLOW WILL VEER TO MORE SELY TONIGHT AND A BROAD LOW LEVEL WAA
REGIME WILL DEVELOP. CONCURRENTLY A VERY WEAK IMPULSE WILL TRACK
THRU THE MID MS VALLEY WITHIN THE NW FLOW ALOFT. BOTH OF THESE
FEATURES WILL PRODUCE SOME WEAK ASCENT WITH THE LOW LEVEL WAA MORE
FOCUSED ACROSS SRN MO AND SRN IL WHILE THE MAIN ASCENT WITH THE
UPPER DISTURBANCE WILL BE FOCUSED NORTH OF THE CWA. MOISTURE IS ALSO
AN ISSUE WITH HIGH LEVEL MOISTURE WITHIN THE NW FLOW ALOFT STREAMING
ACROSS THE AREA WHILE THE SWLY LLJ TRANSPORTS MODEST LOW LEVEL
MOISTURE FROM THE SRN PLAINS AND LOWER MS VALLEY. THE RESULTANT
MOISTURE STRATIFICATION IS HIGH AND LOW WITH MOST OF THE LIFT
INDICATED TO BE IN BETWEEN THE TWO MOISTURE SOURCES WHERE THE AIR
MASS IS DRY. NORMALLY THIS MIGHT SUGGEST DRIZZLY PCPN BUT THE LOW
LEVELS WONT BE THAT DRAMATICALLY MOIST - I.E. IFR AND LOWER CIGS.
THIS IS IN PART DUE TO THE DRY BOUNDARY LAYER CURRENTLY OVER THE
AREA. THE GFS SEEMS TO RECOGNIZE THIS AS DOES THE HRRR AND
RUC...WHICH HAVE NO QPF OR A COUPLE OF SPITS. ALTERNATIVELY THE NAM
AND LOCAL WRF SUGGEST VERY LIGHT QPF OVER THE ENTIRE CWA...HOWEVER
THEY ARE ALREADY IN ERROR AS THERE SHOULD BE PCPN ACROSS OK AND AR.
ADDING TO THE QUANDARY IS THE THERMAL PROFILES WHICH SUGGEST SLEET OR
FREEZING RAIN ACROSS SE MO AND MAINLY SNOW OR SLEET CENTERED ALONG
I-70 AND SNOW FURTHER NORTH. THE BOTTOM LINE IS THAT I THINK DRIZZLE
IS LESS LIKELY AND ANY PCPN THAT OCCURS WILL BE EITHER BE VERY LIGHT
OR SHOWERY IN NATURE...WITH THE GREATEST PROBABILITY ACROSS SE MO
AFTER 06Z. WHATEVER DOES FALL AND ACCUMULATE WILL BE VERY LIGHT.
GIVEN THE UNCERTAINTIES I HAVE KEPT WITH THE CHANCE POPS FROM THE
PREVIOUS FORECAST AND DONT HAVE ANY HEADLINES. THAT SAID...SOME ZL--
OR ZR-- COULD PRODUCE A VERY LIGHT GLAZE ON ANY UNTREATED SURFACES.
I WILL ISSUE AN SPS TO HIGHLIGHT THIS POTENTIAL.
GLASS
&&
.LONG TERM...
ISSUED AT 334 PM CST THU JAN 24 2013
(FRIDAY - SUNDAY)
LIGHT PRECIPITATION SHOULD BE ON THE WAY OUT EARLY TOMORROW MORNING AS
BY 1200 UTC NAM 290-305K ISENTROPIC SURFACES DEPICT SUBSIDENCE WEST OF THE
MISSISSIPPI RIVER WHICH SPREADS EAST WITH TIME. LEFT SCHC POPS FOR THE
EASTERN THIRD OF THE CWA WHERE WEAK MOIST/WARM ADVECTION CONTINUES
UNTIL ROUGHLY 1500 UTC. SKIES SHOULD QUICKLY CLEAR OUT TOMORROW WITH
SUBSIDENCE IN THE WAKE OF SHORTWAVE TROUGH PASSING THROUGH THE GREAT
LAKES REGION. AT THE SFC...A WEAK COLD FRONT/WIND SHIFT WILL COME THROUGH
ATTENDANT TO A SFC CYCLONE ASSOCIATED WITH THE NORTHERN STREAM CLIPPER.
WITH CLEARING SKIES AND A WESTERLY COMPONENT TO THE WIND...WENT ABOVE
WARMEST GUIDANCE YIELDING HIGHS FROM UPPER 30S IN THE NORTH TO NEAR 50
OVER PORTIONS OF SOUTHEAST MISSOURI.
ANOTHER SHOT OF COLD CANADIAN AIR IS IN STORE FOR FRIDAY NIGHT AND SATURDAY
WITH A 1030+ HPA SFC HIGH SLIDING SE INTO THE MID-MISSOURI RIVER VALLEY
BY 0600 UTC SATURDAY. EXPECT LOWS IN THE TEENS AND TWENTIES WITH CLEAR
SKIES AND LOW DEWPOINTS. WINDS SHOULD STAY UP JUST ENOUGH MOST LIKELY TO
PREVENT DECOUPLING AND TEMPERATURES BOTTOMING OUT SEVERAL DEGREES COOLER.
FOR HIGHS ON SATURDAY...COOLEST READINGS WILL BE IN THE M/U 20S OVER
WEST-CENTRAL ILLINOIS AND MID 30S OVER CENTRAL MISSOURI. THESE READINGS
ARE CLOSER TO COOLER MET GUIDANCE GIVEN WEAK CAA AND INCREASING CIRRUS
THROUGHOUT THE DAY.
CLOUDS SHOULD CONTINUE TO BE ON THE INCREASE AND GRADUALLY LOWER THROUGH
SATURDAY NIGHT AS A SHORTWAVE TROUGH EJECTS OUT OF THE DESERT SOUTHWEST.
THE COMBINATION OF STRONG MOIST/WARM ADVECTION AROUND THE WESTERN
PERIPHERY OF A LOW-LEVEL ANTICYCLONE OVER THE GULF COAST AND DCPVA AHEAD
OF THE TROUGH AXIS SHOULD PROVIDE PLENTY OF SUPPORT FOR GOING POPS. WITH
COLD AIR STILL IN PLACE BEHIND DEPARTING CANADIAN AIRMASS AND COLD GROUND
TEMPERATURES FROM PREVIOUS SPELLS OF ARCTIC AIR...POTENTIAL FOR ACCUMULATING
FREEZING RAIN APPEARS LIKELY FOR PORTIONS OF THE AREA. CURRENT EXPECTATION
IS FOR FREEZING RAIN TO BEGIN LATE SATURDAY NIGHT OVER CENTRAL MISSOURI
AND SPREADING E/NE WITH TIME. ONSET OF PRECIPITATION WILL LIKELY BE A
COMBINATION OF SLEET/SNOW DUE TO VERY DRY AMS BELOW 700 HPA LEADING TO
STRONG EVAPORATIONAL COOLING/WET BULBING. HOWEVER...WAA WILL WIN OUT FAIRLY
QUICKLY (WITHIN AN HOUR OR TWO) AND CHANGE PTYPE OVER TO FREEZING RAIN AND
EVENTUALLY RAIN AS SFC TEMPS WARM ABOVE FREEZING. EXCEPTION WOULD BE OVER
NORTHERN SECTIONS OF THE AREA INCLUDING QUINCY WHERE SLEET/SNOW MIX MAY
CONTINUE FOR A FEW HOURS BEFORE CHANGING OVER TO FREEZING RAIN. IN THIS
AREA...HAVE HALF AN INCH OF SNOW OR LESS TO ACCOUNT FOR THIS SCENARIO.
GENERALLY...EXPECTING A 6-HR PERIOD OR SO OF FROZEN PRECIPITATION WITH
FREEZING RAIN BEING THE PRIMARY PTYPE BEFORE THE CHANGEOVER TO
PLAIN OLD RAIN FOR MOST LOCATIONS. AMOUNTS OF FREEZING RAIN IN THE
CURRENT FORECAST ARE ON THE ORDER OF A TENTH OF AN INCH OR
LESS...BUT CERTAINLY ENOUGH TO CREATE TRAVEL PROBLEMS FOR THOSE
VENTURING OUT SUNDAY MORNING. TEMPERATURES BEHIND THE WARM FRONT
WILL CONTINUE TO RISE THROUGH THE OVERNIGHT HOURS SO WENT WITH A
NON-DIURNAL TEMPERATURE TREND FOR SUNDAY NIGHT.
(MONDAY - THURSDAY)
VERY WARM AIR IS IN STORE FOR MONDAY-TUESDAY WITH HIGHS IN THE 50S AND 60S
EACH DAY. MAIN CONCERN WITH REACHING THESE TEMPERATURES IS OBVIOUSLY
CLOUDS/PRECIP CHANCES. MODELS CONTINUE TO PRINT OUT LIGHT QPF EACH DAY...
BUT FORCING SEEMS INNOCUOUS AND BELIEVE MODELS ARE DOING THIS DUE TO THE
VERY STRONG AND ANOMALOUS LOW-LEVEL MOISTURE RETURN. WARMEST DAY SHOULD
BE TUESDAY AHEAD OF FRONT AS NWP GUIDANCE HAS 850-HPA TEMPS AOA +8C.
DEEP MIXING FOR THE TIME OF YEAR TO NEAR 850 HPA AND COMPRESSIONAL WARMING
AHEAD OF FRONT ALL SUGGEST HIGHS NEAR RECORD OR RECORD-BREAKING. THEREFORE...
HAVE OPTED TO INCLUDE RECORD HIGHS AND RECORD HIGH MINIMUMS FOR MONDAY AND
TUESDAY IN THE CLIMO SECTION BELOW. HIGH TEMPERATURES...ESPECIALLY FOR
TUESDAY...WOULD LIKELY BE SEVERAL DEGREES TOO COOL IF THERE ARE BREAKS IN
THE CLOUDS. FOR EARLY WEEK...WENT AT LEAST A FEW DEGREES ABOVE CR
INITIALIZATION DUE TO REASONING MENTIONED ABOVE.
COLD FRONT SHOULD MOVE THROUGH ON THE DAY TUESDAY WITH SHOWERS AND
THUNDERSTORMS STILL A GOOD BET ALONG AND AHEAD OF THE BOUNDARY. ALSO POTENTIAL
FOR SEVERE WEATHER GIVEN STRONG DYNAMICS PROGGED AND INSTABILITY PARAMETERS.
SFC DEWPOINTS MAY EVEN APPROACH 60 DEGREES...WHICH FOR THIS TIME OF YEAR IS
CERTAINLY A RED FLAG FOR POTENTIAL STRONG TO SEVERE STORMS. HOWEVER...THERE
IS STILL QUITE A BIT OF UNCERTAINTY IN REGARDS TO EXACT TRACK OF SFC LOW
AND AMOUNT OF INSTABILITY AHEAD OF BOUNDARY. NEW ECMWF WHICH CUTS OFF
SHORTWAVE TROUGH OFF THE COAST OF CALIFORNIA WITH A NORTHERN STREAM SHORTWAVE
TRAVERSING THE NORTHERN PLAINS IS AN OUTLIER AND WAS DISCOUNTED FOR NOW.
THIS SCENARIO WOULD HAVE A WEAKER FROPA EARLIER ON TUESDAY WITH LESS
DYNAMICS FOR SEVERE WEATHER.
BEHIND THE COLD FRONT...WEDNESDAY AND THURSDAY LOOK MUCH COOLER...I.E....
TOWARD SEASONAL NORMS WITH HIGHS IN THE 30S AND 40S. THIS TIME PERIOD
ALSO WILL LIKELY BE DRY...THOUGH SOME MODELS HAVE HINTED AT THE POSSIBILITY
OF SOME ENERGY LAGGING BEHIND IN THE FOUR-CORNERS REGION WHICH COULD YIELD
POTENTIALLY WINTRY WEATHER SOMETIME LATER NEXT WEEK.
GOSSELIN
&&
.AVIATION...
ISSUED AT 539 PM CST THU JAN 24 2013
THE MAIN FCST CHALLENGE IS IF ANY WINTRY PRECIP WILL FALL LATE
TONIGHT. STRONG HIGH PRESSURE CONTINUES TO SLIDE SE FROM THE GRT
LKS REGION TO THE ERN SEABOARD BY TOMORROW. AS THE HIGH PULLS AWAY
TONIGHT WINDS WILL BECOME SERLY. A WEAK AREA OF LOW PRESSURE IS
FCST TO DVLP TONIGHT ACROSS ERN TX AND THEN SLIDE NE ALONG THE
FRONT TO THE ERN GRT LKS BY TOMORROW EVENING. THIS WILL ALLOW
WARMER AND MORE MOIST AIR TO MOVE NORTH OVER TOP THE COLDER AIR AT
THE SFC. THERE IS AN UPPER LEVEL DISTURBANCE THAT IS FCST TO SLIDE
PAST TO THE NORTH OF THE AREA FRIDAY MORNING. MOST OF THE ENERGY
WITH THIS SYSTEM WILL REMAIN NORTH OF OUR AREA. AT THIS POINT...I/M NOT
CONFIDENT ENOUGH THAT ANYTHING WILL HAPPEN TO CHANGE THE EXISTING
PROB30 GROUPS. IF PRECIP DOES DVLP...IT SHOULD BE VERY LIGHT AND BRIEF.
THE BEST CHANCE FOR PRECIP APPEARS TO BE RIGHT BEFORE SUNRISE
ACROSS SE MO AND FAR STHRN IL AS WELL AS NE MO AND W CNTRL IL WITH
THE I70 CORRIDOR IN AN AREA OF LOWER CHANCES OF PRECIP. IF PRECIP
DVLPS...IT SHOULD BE EAST OF KCOU BY THE TIME IT DOES. THERMAL
PROFILES INDICATE THAT IF ANY PRECIP DOES DVLP THAT IT WOULD
PRIMARILY BE SNOW AT KUIN AND A MIX OF FREEZING RAIN/DRIZZLE
AND/OR SLEET IN THE STL METRO AREA AND MOSTLY FREEZING RAIN ACROSS
SE MO AND STHRN IL. A COLD FRONT IS SCHEDULED TO COME THRU FRIDAY
MORNING ENDING THE THREAT OF PRECIP AND TURNING WINDS TO THE WEST. SKIES
SHOULD SLOWLY CLEAR FROM W-E AFTER FROPA.
SPECIFICS FOR KSTL...
CLOUDS WILL SLOWLY THICKEN OVERNIGHT AS WINDS BECOME SSERLY IN
ADVANCE OF A WEAK STORM SYSTEM DUE IN AFTER MIDNIGHT. BIG QUESTION
IS WHETHER IT WILL PRECIPITATE TONIGHT OR NOT. MY HUNCH IS NO. THE
STL METRO AREA IS BETWEEN TWO AREAS OF LIFT AND THERE IS A LOT OF
DRY AIR TO OVERCOME NEAR THE SFC. I THINK MOST OF ANY POTENTIAL
PRECIP WILL EVAPORATE BEFORE REACHING THE GROUND. IF ANYTHING IS
ABLE TO MAKE IT THAT FAR IT SHOULD BE IN THE FORM OF FREEZING
RAIN/DRIZZLE AND/OR SLEET. THIS IS NOT EXPECTED TO BE A BIG DEAL.
AMOUNTS SHOULD BE LIGHT AND THE DURATION BRIEF...ON THE ORDER OF A
COUPLE OF HOURS. COLD FRONT COMES THRU TOMORROW MORNING ENDING THE
PRECIP THREAT AND SKIES SHOULD CLEAR AFTER FROPA.
2%
&&
.CLIMATE...
ISSUED AT 334 PM CST THU JAN 24 2013
RECORD OR NEAR RECORD-BREAKING TEMPERATURES ARE EXPECTED ON MONDAY
AND TUESDAY. BELOW IS A TABLE OF RECORD HIGHS AND RECORD HIGH
MINIMUMS FOR ARE THREE OFFICIAL CLIMATE STATIONS: ST. LOUIS
(STL)...COLUMBIA (COU)...AND QUINCY (UIN):
ST. LOUIS
HIGH HIGH MINIMUM
1/2876 (1970)53 (1914)
1/2973 (2008)44 (1947)
COLUMBIA
HIGH HIGH MINIMUM
1/28 67 (2002) 53 (1914)
1/29 64 (2008) 44 (1938)
QUINCY
HIGH HIGH MINIMUM
1/28 63 (1914) 46 (1914)
1/29 63 (1914) 38 (1989)
&&
.PRELIMINARY POINT TEMPS/POPS...
ST LOUIS 23 45 22 31 / 40 20 5 0
QUINCY 19 37 14 26 / 50 10 5 0
COLUMBIA 23 46 20 36 / 20 10 5 0
JEFFERSON CITY 25 47 19 37 / 20 10 5 0
SALEM 23 42 22 30 / 50 20 5 0
FARMINGTON 25 48 22 34 / 50 20 5 0
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
600 PM CST THU JAN 24 2013
.AVIATION...00Z KGRI TAF. MVFR CIGS MAY LAST ABOUT AN HOUR OR
SO...THEN HEAD EAST. VFR CONDITIONS AFTERWARD AS WIND BECOMES
MORE WEST WITH TIME.
&&
.PREV DISCUSSION... /ISSUED 254 PM CST THU JAN 24 2013/
SHORT TERM...TONIGHT THROUGH FRIDAY AFTERNOON...PLENTY OF CLOUD
COVER ACROSS THE REGION THIS AFTERNOON AS A WARM FRONT ACROSS
WESTERN NEBRASKA IS SLOWLY PROGRESSING EASTWARD. THIS THICK CLOUD
COVER HAS LIMITED SOLAR HEATING TODAY...AND WITH A COLD AIRMASS
IN PLACE...HAVE STRUGGLED TO CLIMB OUT OF THE TEENS SO FAR IN
SPOTS...WHILE IN WESTERN NEBRASKA BEHIND THE WARM FRONT...
TEMPERATURES MANAGED TO CLIMB INTO THE LOWER 60S.
AS THIS WARM FRONT CROSS THE LOCAL AREA DURING THE EVENING
HOURS...EXPECT LOW TEMPERATURES TO BE REALIZED JUST AHEAD OF THE
BOUNDARY PASSAGE...WITH STEADY OR SLOWLY RISING TEMPERATURES
POSSIBLE OVERNIGHT. WITH HRRR AND NAM IN FAIR AGREEMENT...TAKING
THIS FRONT ACROSS KGRI AROUND 3Z...WENT AHEAD AND ADJUSTED HOURLY
TEMPERATURE GRIDS TO REFLECT LOW TEMPERATURES AT MOST AREAS BETWEEN
00Z AND 04Z THIS EVENING. OTHER THAN THE WARMER AIRMASS AND SWITCH
TO MORE SOUTHWESTERLY WINDS WITH THE PASSAGE OF THIS FRONT...NO
OTHER IMPACTS ARE EXPECTED.
FOR FRIDAY...EXPECT THE WARMER AIRMASS IN PLACE ACROSS THE LOCAL
AREA COMBINED WITH LIGHT WEST NORTHWESTERLY DOWNSLOPE FLOW...TO
HELP AFTERNOON TEMPERATURES SOAR PAST SEASONAL NORMALS...WITH MID
TO UPPER 40S FORECAST FOR MOST LOCATIONS. A PASSING SHORTWAVE OVER
THE TOP OF THE RIDGE IS EXPECTED TO REMAIN WELL TO THE NORTH OF
THE LOCAL AREA...WITH THE ASSOCIATED SURFACE COLD FRONT NOT
EXPECTED TO REACH THE LOCAL AREA. THEREFORE...WITH THINNING CLOUD
COVER BEHIND THE WARM FRONT AND LIGHT NORTHWESTERLY SURFACE
WINDS...A MOSTLY SUNNY AND PLEASANT END TO THE WEEK IS EXPECTED
ACROSS THE REGION.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY. MAIN FORECAST CONCERNS
WILL BE CHANCE FOR PRECIPITATION SATURDAY NIGHT INTO SUNDAY AND
AGAIN MONDAY NIGHT INTO TUESDAY AND TEMPERATURES THROUGH THE PERIOD.
A BROAD UPPER LEVEL RIDGE WILL DRIFT THROUGH THE AREA FRIDAY NIGHT
AND SATURDAY. TEMPERATURES FRIDAY NIGHT WILL STILL DROP INTO THE
TEENS AND LOWER 20S. DURING THE DAY WINDS WILL TURN TO THE SOUTH AND
WITH WARM ADVECTION THE TEMPERATURES SHOULD RISE INTO THE 40S TO
LOWER 50S.
BY SATURDAY NIGHT THERE IS AN UPPER LEVEL WAVE THAT MOVES INTO THE
AREA. THE SOUTH WINDS DURING THE DAY ON SATURDAY WILL BRING MOIST
AIR INTO THE AREA. BY SATURDAY NIGHT THERE ARE SOME DIFFERENCES IN
THE LOCATION OF THE PRECIPITATION DURING THE NIGHT. THE GFS BRINGS
MORE PRECIPITATION INTO THE AREA WHERE THE ECMWF AND THE NAM KEEP
THE PRECIPITATION FURTHER TO THE SOUTH. HAVE LOWERED THE CHANCES FOR
PRECIPITATION FOR THE NORTH AND WEST A BIT. THE QUESTION BECOMES
WHAT TYPE OF PRECIPITATION TO EXPECT. MOST OF THE NIGHT THERE WILL
BE RAIN AS THE TEMPERATURES WILL BE WARM ENOUGH FOR PRECIPITATION TO
REMAIN LIQUID. THE PROBLEM BECOMES TOWARD MORNING AS PRECIPITATION
SPREADS FURTHER TO THE NORTH. THERE COULD BE A BRIEF PERIOD OF SOME
FREEZING RAIN FURTHER NORTH. BY SUNDAY MORNING THE TEMPERATURES
SHOULD WARM UP AND PRECIPITATION SHOULD TURN TO RAIN ACROSS THE
AREA. BY LATER IN THE DAY ON SUNDAY THE RAIN SHOULD START TO MOVE
OUT OF THE AREA.
SUNDAY NIGHT AND MONDAY THERE WILL BE A DEVELOPING WAVE IN THE
WESTERN CONUS AND SOUTHWEST FLOW ACROSS THE AREA. THERE WILL BE WARM
ADVECTION AND MILD TEMPERATURES.
BY MONDAY NIGHT THE UPPER LEVEL WAVE STARTS TO AFFECT THE FORECAST
AREA. MODELS HAVE SOME DIFFERENCES IN THE PROGRESSION OF THE WAVE
ACROSS THE AREA. THE GFS IS FASTER WITH A MORE OPEN WAVE WHILE THE
ECMWF IS SLOWER WITH A CLOSED LOW. HAVE KEPT THE PRECIPITATION IN
ACROSS THE AREA FOR MONDAY NIGHT INTO TUESDAY WHICH IS CLOSER TO THE
GFS. THERE IS COLDER AIR MOVING INTO THE AREA BEHIND A COLD FRONT
THAT MOVES THROUGH MONDAY NIGHT. EXPECT RAIN OR SNOW MONDAY NIGHT
WITH THE COLDER AIR MOVING INTO THE AREA. THEN ON TUESDAY THERE WILL
BE SNOW FURTHER WEST OR NORTHWEST WHERE THE COLDER AIR IS...RAIN IN
THE SOUTHEAST AND A MIX OF RAIN OR SNOW POSSIBLE IN BETWEEN.
COLD AIR CONTINUES ACROSS THE AREA ON WEDNESDAY BUT THERE IS A
LITTLE WARM ADVECTION AND TEMPERATURES WARM A LITTLE FOR THURSDAY.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1030 PM EST THU JAN 24 2013
.SYNOPSIS...
COLD TEMPERATURES WILL CONTINUE THROUGH SATURDAY. SCATTERED LAKE
EFFECT SNOW SHOWERS AND FLURRIES WILL PERSIST OVERNIGHT PRIMARILY
OVER THE FINGER LAKES REGION INTO THE SYRACUSE AREA...AND PORTIONS
OF THE SOUTHERN TIER OF NEW YORK. OTHERWISE...HIGH PRESSURE WILL
PROVIDE DRY CONDITIONS THROUGH MIDDAY FRIDAY. A WEAK SYSTEM WILL
BRING WIDESPREAD LIGHT SNOW FRIDAY AFTERNOON INTO FRIDAY NIGHT. ON
SATURDAY, BEHIND THIS SYSTEM A NORTHWEST FLOW OF COLD AIR WILL
PRODUCE MORE SNOW SHOWERS FOR CENTRAL NEW YORK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
1030 PM UPDATE...
VERY LOW WATER CONTENT LAKE EFFECT FLURRIES AND SNOW SHOWERS ARE
IMPACTING AREAS MAINLY BETWEEN THE SOUTHERN TIER AND NEW YORK
THRUWAY...BARELY SHOWING UP ON RADAR IF AT ALL. CAYUGA LAKE BAND
IS MANAGING TO APPEAR ON RADAR CONNECTION FROM NEAR ITHACA TO
BINGHAMTON AIRPORT.
RUC/RAP AND NAM DATA FORESHADOWED THAT BAND OF HIGH LOW LEVEL RH
AND MINOR OMEGA WOULD LINE UP WITH UPSTREAM GEORGIAN BAY CONNECTION
FOR AT LEAST A TIME OVERNIGHT...EVIDENCED ALSO BY RUNNING HYSPLIT
MODEL. PRECIPITATION IS VERY LIGHT BUT IS CONFIRMING THIS TREND.
WHILE UPSTREAM CONNECTION BREAKS AS FLOW QUICKLY BACKS BY
06Z-09Z AT GEORGIAN BAY...AIR PARCELS PREVIOUSLY RESIDENT OVER THE
BAY WILL STILL BE FINISHING ADVECTING OVER CENTRAL NY AT THAT
TIME. MOISTURE IS VERY SHALLOW YET IS ALSO ENTIRELY IN DENDRITIC
ZONE TEMPERATURES WITH AT LEAST SOME WEAK LIFT. THIS KIND OF
ARCTIC AIR MASS NEEDS VERY LITTLE MOISTURE TO YIELD A LIGHT
COATING OF DRY FLUFF. IN PARTICULAR...SOME OF THE HIGH TERRAIN
SOUTH OF SYRACUSE INTO CORTLAND COUNTY COULD PICK UP SEVERAL
TENTHS OF AN INCH...TO PERHAPS LOCALLY NEAR AN INCH. GRIDS HAVE
BEEN FINE TUNED AS NEEDED. TO NORTH OF BAND...TRENDS IN RH FIELDS
BETWEEN SURFACE AND 900MB SUGGEST THAT SNOW SHOWERS WILL PROBABLY
NOT EDGE BACK ACROSS ONEIDA COUNTY DURING THE NIGHT...BECAUSE
NEAR-SURFACE FLOW TAKES TOO LONG TO BACK WESTERLY.
TEMPERATURES WERE ALSO TWEAKED ESPECIALLY WHERE LAKE EFFECT CLOUDS
WILL HOLD PREVENT FULL PLUMMET. GENERALLY LOWS WILL BE SEVERAL
DEGREES ABOVE ZERO UNDER LAKE EFFECT CLOUDS...PLUS OR MINUS A FEW
DEGREES FROM ZERO ELSEWHERE. NOTABLE EXCEPTION WILL BE ONEIDA
COUNTY...RANGING FROM 5 TO 15 DEGREES BELOW ZERO.
DESPITE DIMINISHING WINDS...WIND CHILLS WILL STILL MANAGE TO
ECLIPSE 15 BELOW ZERO AT TIMES IN PORTIONS OF THE NORTHERN
SUSQUEHANNA REGION...WESTERN CATSKILLS AND ONEIDA COUNTY
/ESPECIALLY HIGHER ELEVATIONS/. NORTHERN ONEIDA COUNTY IN
PARTICULAR...WHERE WIND CHILL COULD EVEN GET INTO MINUS-20S AT
TIMES. THUS...THE ONGOING WIND CHILL ADVISORY INTO FRIDAY MORNING
STILL LOOKS GOOD FOR THE ASSOCIATED ZONES.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
FRIDAY/FRIDAY NIGHT...NORTHERN STREAM SHORT WAVE AND ASSOCIATED
WEAK SFC LOW WILL MOVE THROUGH THE UPPER GREAT LAKES AS A SOUTHERN
STREAM SYSTEM MOVES THROUGH THE MID ATLANTIC. REGION IS REALLY
BETWEEN SYSTEMS WITH MODELS IN VERY GOOD AGREEMENT SHOWING LOW QPF
THROUGHOUT THE EVENT FOR FA. FOR OUR AREA THERE EXISTS VERY LITTLE
IN THE WAY OF JET DYNAMICS, ISENTROPIC LIFT OR AVAILABLE MOISTURE
MAKING LOW QPF AMOUNTS SEEM VERY REASONABLE. WILL CONTINUE TO
ADVERTISE A HIGH POPS LOW QPF FORECAST WITH POPS INCREASING INTO
THE CATEGORICAL/LIKELY RANGE BY EARLY FRIDAY EVENING. WILL
CONTINUE WITH CATEGORICAL POPS THROUGH THE EVENING HOURS THEN
QUICKLY DROP POPS BACK INTO THE CHC RANGE SHORTLY AFTER MIDNIGHT.
TOTAL SNOWFALL WILL BE AROUND AN INCH ACROSS THE NRN CWA AND 1 TO
2 INCHES FOR THE SOUTHERN TIER, WESTERN CATSKILLS AND NE PA.
SATURDAY/SATURDAY NIGHT...A FAIRLY STRONG H5 SHORT WAVE IN
NORTHWEST FLOW WILL DROP THROUGH THE REGION DURING THE AFTERNOON.
ATTM NORTHWEST FLOW WILL ALSO BE INCREASING BEHIND DEPARTED
SYSTEM. THIS WILL SET THE STAGE FOR MORE SNOW SHOWERS ACROSS
CENTRAL NY WITH POTENTIALLY MORE ORGANIZED LAKE EFFECT SNOWS
SOUTHEAST OF LAKE ONTARIO UNDER NORTHWEST FLOW. MODEL SOUNDINGS
SHOW FAIRLY DEEP MOISTURE AND INSTABILITY SATURDAY AFTERNOON
THROUGH EARLY EVENING BEFORE INVERSION COME CRASHING DOWN. DURING
THIS PERIOD WILL CARRY LIKELY POPS SE OF LAKE ONTARIO WITH SNOW
ACCUMS OF SEVERAL INCHES POSSIBLE. AFTER MIDNIGHT LOWERING
INVERSION AND DRIER AIR WILL WEAKEN ANY LINGERING ACTIVITY. REST
OF AREA WILL SEE PARTLY TO MAINLY CLEAR SKIES ALONG WITH COLD
TEMPS. LOWS WILL GENERALLY RANGE FROM 5 BELOW ZERO TO 10 ABOVE.
SUNDAY...UPPER LEVEL RIDGING AND SFC HIGH PRES IN VCNTY WILL MAKE
FOR A PARTLY TO MOSTLY SUNNY DAY ALONG WITH TEMPS MODERATING INTO
THE LOWER TO MIDDLE 20S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
PERIOD BEGINS WITH A COLD HIGH SLIDING OFF THE ATLANTIC COAST,
WITH AN UL RIDGE BUILDING THROUGH THE OHIO VALLEY. A STRONG JET
WILL DIVE INTO THE MOUNTAIN WEST, CAUSING A DEEP TROF TO DEVELOP
OVER THE WESTERN THIRD OF THE CONUS. A MILDER RIDGE WILL BUILD
THROUGH THE EASTERN U.S., WITH DAYTIME MAXES PUSHING WELL INTO THE
40S BY TUESDAY OR WEDNESDAY.
WEAK WAVES MOVING THROUGH THE FLOW WILL KEEP THE POTENTIAL FOR
SCATTERED RAIN OR WET SNOW SHOWERS OVER OUR FORECAST AREA MONDAY.
TUESDAY INTO WEDNESDAY, A CYCLONE WILL STRENGTHEN OVER THE
NORTHERN PLAINS, DRAGGING A WARM FRONT ACROSS THE OHIO VALLEY AND
WESTERN NEW YORK. A COLD FRONT WILL FOLLOW WEDNESDAY AFTERNOON, AS
THE SYSTEM MOVES INTO EASTERN ONTARIO.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
700 PM UPDATE...
OVERALL MAINLY VFR EXPECTED TONIGHT INTO THE FIRST PART OF
TOMORROW...BEFORE LIGHT SNOW BRINGS RESTRICTIONS TO MOST OF THE
TERMINALS BY FRIDAY EVENING. THE BIGGEST PROBLEM TERMINALS TONIGHT
WILL BE KSYR/KITH IN VERY LIGHT LAKE EFFECT SNOW AND/OR FLURRIES
ON A MOISTURE...BUT SHALLOW...NORTHWEST FLOW.
AT KSYR...IFR VSBYS CONTINUE DESPITE VERY WEAK RETURNS ON RADAR.
THE RAP MODEL HAS THE BEST HANDLE ON THE SITUATION SHOWING LOW
LEVEL LIFT AND MOISTURE AROUND 2500 FEET. MODEL TRENDS ARE TO
SUPPRESS THE BEST LIFT AND MOISTURE FARTHER SOUTH OVER THE NEXT
FEW HOURS. A LOW CONFIDENCE FORECAST THAT IFR WILL EVEN HOLD ON
FOR AS LONG AS I HAVE BUT GIVEN WE ARE SEEING IT NOW...CONTINUED
IFR VSBYS OF 2SM IN LIGHT SNOW THROUGH 04Z. AFTER THAT TIME WHILE
SOME FLURRIES ARE POSSIBLE RESTRICTIONS DO NOT APPEAR AS LIKELY.
VFR FRIDAY UNTIL VERY LATE IN THE DAY IN LIGHT SNOW.
AT KITH...A LIGHT BAND OF SNOW IS JUST NORTH OF THE TERMINAL NOW
AND BASED ON INCREASING LOW LEVEL MOISTURE AND LIFT BORDERLINE IFR
VSBYS IN LIGHT SNOW APPEAR MOST LIKELY AFTER 02Z. CONFIDENCE AGAIN
LOW GIVEN THAT THE SNOW WILL BE SO LIGHT BUT JUST ENOUGH TO
PRODUCE 2SM. MOISTURE PROFILES AND LIFT LOOK GOOD THROUGH 10Z FOR
SNOW AND WILL CONVEY THIS IN THE TAFS. AS THE COLUMN DRIES OUT
VFR EXPECTED AFTER THAT TIME UNTIL LATE IN THE DAY.
AT KRME...BRIEF MVFR VSBYS POSSIBLE THE NEXT HOUR OR TWO OTHERWISE
BECOMING VFR AND REMAINING THAT WAY THROUGH FRIDAY AFTERNOON.
AT KBGM...MVFR CIGS OR VSBYS DEVELOPING AND PERSISTING IN THE 03Z
-09Z PERIOD. LOW CONFIDENCE THAT WE MAY SEE SOME IFR VSBYS HERE
BUT NOT HIGH ENOUGH TO INCLUDE IN THE TAFS. WE WOULD BE TALKING
2SM AT MOST. SNOW LATE IN THE DAY FRIDAY WITH IFR.
AT KAVP...VFR TONIGHT/EARLY TOMORROW WITH IFR VSBYS BY 21Z IN
LIGHT SNOW FRIDAY.
WINDS BRISK 5 TO 10 KTS THIS EVENING...BECOMING LIGHT NORTHWEST AT
5 KTS OR LESS TONIGHT. LIGHT/VARIABLE WINDS FRIDAY.
.OUTLOOK...
FRI...MVFR LATE IN THE DAY.
FRI NIGHT...MVFR IN SHSN.
SAT...MVFR IN -SHSN AT CNY TERMINALS.
SUN...VFR.
MON...MVFR IN RA/SN.
TUE...MVFR IN -RA.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...WIND CHILL ADVISORY UNTIL 9 AM EST FRIDAY FOR NYZ009-036-037-
045-046-057.
&&
$$
SYNOPSIS...MDP/RRM
NEAR TERM...MDP
SHORT TERM...RRM
LONG TERM...DJP
AVIATION...HEDEN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
716 PM EST THU JAN 24 2013
.SYNOPSIS...
COLD TEMPERATURES WILL CONTINUE THROUGH SATURDAY. SCATTERED LAKE
EFFECT SNOW SHOWERS AND FLURRIES WILL PERSIST THROUGH THIS EVENING
PRIMARILY OVER THE FINGER LAKES REGION INTO THE SYRACUSE AREA.
OTHERWISE, HIGH PRESSURE WILL PROVIDE DRY CONDITIONS THROUGH
MIDDAY FRIDAY. A WEAK STORM SYSTEM WILL BRING WIDESPREAD LIGHT
SNOW FRIDAY AFTERNOON INTO FRIDAY NIGHT. ON SATURDAY, BEHIND THIS
SYSTEM A NORTHWEST FLOW OF COLD AIR WILL PRODUCE MORE SNOW SHOWERS
FOR CENTRAL NEW YORK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
715 PM UPDATE...
VERY LOW WATER CONTENT LAKE EFFECT FLURRIES AND SNOW SHOWERS ARE
IMPACTING PARTS OF THRUWAY COUNTRY...BARELY SHOWING UP ON RADAR IF
AT ALL. HOWEVER...RUC/RAP AND NAM DATA SUGGEST THAT BAND OF HIGH LOW
LEVEL RH AND MINOR OMEGA WILL LINE UP WITH UPSTREAM GEORGIAN BAY
CONNECTION FOR AT LEAST A TIME OVERNIGHT...BACKED UP BY RUNNING
HYSPLIT MODEL. WHILE UPSTREAM CONNECTION BREAKS AS FLOW QUICKLY
BACKS BY 06Z-09Z AT GEORGIAN BAY...AIR PARCELS PREVIOUSLY RESIDENT
OVER THE BAY WILL STILL BE FINISHING ADVECTING OVER CENTRAL NY AT
THAT TIME. MOISTURE IS VERY SHALLOW YET IS ALSO ENTIRELY IN
DENDRITIC ZONE TEMPERATURES WITH AT LEAST SOME WEAK LIFT. I FEEL
THAT THE WRITING IS ON THE WALL FOR LES BAND SHIFTING FROM SYR TO
POINTS FARTHER SOUTH WITH SLIGHT VEERING OF WIND LATER THIS EVENING.
THIS KIND OF ARCTIC AIR MASS NEEDS VERY LITTLE MOISTURE TO YIELD A
LIGHT COATING OF DRY FLUFF. IN PARTICULAR...SOME OF THE HIGH TERRAIN
SOUTH OF SYRACUSE INTO CORTLAND COUNTY COULD PICK UP PERHAPS AN INCH
OR SO. GRIDS HAVE BEEN UPDATED ACCORDINGLY...INCLUDING HIGHER MORE
DETERMINISTIC POPS...AND ALLOWING AT LEAST SCATTERED SNOW SHOWERS TO
ENTER AS FAR SOUTH AS ITHACA AND BINGHAMTON AREAS. ON THE FLIP
SIDE...ALSO CUT BACK NORTHERN END OF BAND...CLEARING OUT MOST OF
ONEIDA COUNTY FOR A GOOD PART OF THE NIGHT BEFORE BRINGING SCATTERED
FLURRIES OR SNOW SHOWERS BACK IN TOWARDS DAWN AS FLOW BACKS.
PREVIOUS DISCUSSION...
AT 400 PM...LOCAL RADARS CONTINUE TO SHOWERS SCATTERED FLURRIES AND
SNOW SHOWERS ACROSS THE FINGER LAKES REGION INTO THE SOUTHERN TIER.
THIS ACTIVITY WILL GRADUALLY DIMINISH EARLY THIS EVENING WITH LOSS
OF DIURNAL HEATING. LOW LEVEL FLOW WILL GRADUALLY BACK OVERNIGHT
SHIFTING ANY LAKE EFFECT SNOW SHOWERS NORTH ALONG THE LAKE PLAIN.
ACTIVITY WILL REMAIN WEAK AS MODEL SOUNDINGS SHOW A LOW INVERSION
ALONG WITH DRY AIRMASS.
OVERNIGHT LOWS WILL DROP BELOW ZERO ACROSS MOST AREAS WITH JUST
THE LAKE PLAIN AND PARTS OF NE PA REMAINING IN THE SINGLE NUMBERS.
THE COLDEST AREAS, WESTERN CATSKILLS AND ONEIDA COUNTY WILL SEE
READINGS OF 10 TO 15 DEGREES BELOW ZERO. SINCE WINDS ACROSS THE
NORTHERN SUSQUEHANNA REGION, WESTERN CATSKILLS AND ONEIDA COUNTY,
WILL CONTINUE AT 10 TO 15 MPH INTO THE EARLY EVENING THEN DIMINISH
TO 5 TO 10 MPH OVERNIGHT WILL EXTEND WIND CHILL ADVISORY INTO
FRIDAY MORNING.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
FRIDAY/FRIDAY NIGHT...NORTHERN STREAM SHORT WAVE AND ASSOCIATED
WEAK SFC LOW WILL MOVE THROUGH THE UPPER GREAT LAKES AS A SOUTHERN
STREAM SYSTEM MOVES THROUGH THE MID ATLANTIC. REGION IS REALLY
BETWEEN SYSTEMS WITH MODELS IN VERY GOOD AGREEMENT SHOWING LOW QPF
THROUGHOUT THE EVENT FOR FA. FOR OUR AREA THERE EXISTS VERY LITTLE
IN THE WAY OF JET DYNAMICS, ISENTROPIC LIFT OR AVAILABLE MOISTURE
MAKING LOW QPF AMOUNTS SEEM VERY REASONABLE. WILL CONTINUE TO
ADVERTISE A HIGH POPS LOW QPF FORECAST WITH POPS INCREASING INTO
THE CATEGORICAL/LIKELY RANGE BY EARLY FRIDAY EVENING. WILL
CONTINUE WITH CATEGORICAL POPS THROUGH THE EVENING HOURS THEN
QUICKLY DROP POPS BACK INTO THE CHC RANGE SHORTLY AFTER MIDNIGHT.
TOTAL SNOWFALL WILL BE AROUND AN INCH ACROSS THE NRN CWA AND 1 TO
2 INCHES FOR THE SOUTHERN TIER, WESTERN CATSKILLS AND NE PA.
SATURDAY/SATURDAY NIGHT...A FAIRLY STRONG H5 SHORT WAVE IN
NORTHWEST FLOW WILL DROP THROUGH THE REGION DURING THE AFTERNOON.
ATTM NORTHWEST FLOW WILL ALSO BE INCREASING BEHIND DEPARTED
SYSTEM. THIS WILL SET THE STAGE FOR MORE SNOW SHOWERS ACROSS
CENTRAL NY WITH POTENTIALLY MORE ORGANIZED LAKE EFFECT SNOWS
SOUTHEAST OF LAKE ONTARIO UNDER NORTHWEST FLOW. MODEL SOUNDINGS
SHOW FAIRLY DEEP MOISTURE AND INSTABILITY SATURDAY AFTERNOON
THROUGH EARLY EVENING BEFORE INVERSION COME CRASHING DOWN. DURING
THIS PERIOD WILL CARRY LIKELY POPS SE OF LAKE ONTARIO WITH SNOW
ACCUMS OF SEVERAL INCHES POSSIBLE. AFTER MIDNIGHT LOWERING
INVERSION AND DRIER AIR WILL WEAKEN ANY LINGERING ACTIVITY. REST
OF AREA WILL SEE PARTLY TO MAINLY CLEAR SKIES ALONG WITH COLD
TEMPS. LOWS WILL GENERALLY RANGE FROM 5 BELOW ZERO TO 10 ABOVE.
SUNDAY...UPPER LEVEL RIDGING AND SFC HIGH PRES IN VCNTY WILL MAKE
FOR A PARTLY TO MOSTLY SUNNY DAY ALONG WITH TEMPS MODERATING INTO
THE LOWER TO MIDDLE 20S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
PERIOD BEGINS WITH A COLD HIGH SLIDING OFF THE ATLANTIC COAST,
WITH AN UL RIDGE BUILDING THROUGH THE OHIO VALLEY. A STRONG JET
WILL DIVE INTO THE MOUNTAIN WEST, CAUSING A DEEP TROF TO DEVELOP
OVER THE WESTERN THIRD OF THE CONUS. A MILDER RIDGE WILL BUILD
THROUGH THE EASTERN U.S., WITH DAYTIME MAXES PUSHING WELL INTO THE
40S BY TUESDAY OR WEDNESDAY.
WEAK WAVES MOVING THROUGH THE FLOW WILL KEEP THE POTENTIAL FOR
SCATTERED RAIN OR WET SNOW SHOWERS OVER OUR FORECAST AREA MONDAY.
TUESDAY INTO WEDNESDAY, A CYCLONE WILL STRENGTHEN OVER THE
NORTHERN PLAINS, DRAGGING A WARM FRONT ACROSS THE OHIO VALLEY AND
WESTERN NEW YORK. A COLD FRONT WILL FOLLOW WEDNESDAY AFTERNOON, AS
THE SYSTEM MOVES INTO EASTERN ONTARIO.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
700 PM UPDATE...
OVERALL MAINLY VFR EXPECTED TONIGHT INTO THE FIRST PART OF
TOMORROW...BEFORE LIGHT SNOW BRINGS RESTRICTIONS TO MOST OF THE
TERMINALS BY FRIDAY EVENING. THE BIGGEST PROBLEM TERMINALS TONIGHT
WILL BE KSYR/KITH IN VERY LIGHT LAKE EFFECT SNOW AND/OR FLURRIES
ON A MOISTURE...BUT SHALLOW...NORTHWEST FLOW.
AT KSYR...IFR VSBYS CONTINUE DESPITE VERY WEAK RETURNS ON RADAR.
THE RAP MODEL HAS THE BEST HANDLE ON THE SITUATION SHOWING LOW
LEVEL LIFT AND MOISTURE AROUND 2500 FEET. MODEL TRENDS ARE TO
SUPPRESS THE BEST LIFT AND MOISTURE FARTHER SOUTH OVER THE NEXT
FEW HOURS. A LOW CONFIDENCE FORECAST THAT IFR WILL EVEN HOLD ON
FOR AS LONG AS I HAVE BUT GIVEN WE ARE SEEING IT NOW...CONTINUED
IFR VSBYS OF 2SM IN LIGHT SNOW THROUGH 04Z. AFTER THAT TIME WHILE
SOME FLURRIES ARE POSSIBLE RESTRICTIONS DO NOT APPEAR AS LIKELY.
VFR FRIDAY UNTIL VERY LATE IN THE DAY IN LIGHT SNOW.
AT KITH...A LIGHT BAND OF SNOW IS JUST NORTH OF THE TERMINAL NOW
AND BASED ON INCREASING LOW LEVEL MOISTURE AND LIFT BORDERLINE IFR
VSBYS IN LIGHT SNOW APPEAR MOST LIKELY AFTER 02Z. CONFIDENCE AGAIN
LOW GIVEN THAT THE SNOW WILL BE SO LIGHT BUT JUST ENOUGH TO
PRODUCE 2SM. MOISTURE PROFILES AND LIFT LOOK GOOD THROUGH 10Z FOR
SNOW AND WILL CONVEY THIS IN THE TAFS. AS THE COLUMN DRIES OUT
VFR EXPECTED AFTER THAT TIME UNTIL LATE IN THE DAY.
AT KRME...BRIEF MVFR VSBYS POSSIBLE THE NEXT HOUR OR TWO OTHERWISE
BECOMING VFR AND REMAINING THAT WAY THROUGH FRIDAY AFTERNOON.
AT KBGM...MVFR CIGS OR VSBYS DEVELOPING AND PERSISTING IN THE 03Z
-09Z PERIOD. LOW CONFIDENCE THAT WE MAY SEE SOME IFR VSBYS HERE
BUT NOT HIGH ENOUGH TO INCLUDE IN THE TAFS. WE WOULD BE TALKING
2SM AT MOST. SNOW LATE IN THE DAY FRIDAY WITH IFR.
AT KAVP...VFR TONIGHT/EARLY TOMORROW WITH IFR VSBYS BY 21Z IN
LIGHT SNOW FRIDAY.
WINDS BRISK 5 TO 10 KTS THIS EVENING...BECOMING LIGHT NORTHWEST AT
5 KTS OR LESS TONIGHT. LIGHT/VARIABLE WINDS FRIDAY.
.OUTLOOK...
FRI...MVFR LATE IN THE DAY.
FRI NIGHT...MVFR IN SHSN.
SAT...MVFR IN -SHSN AT CNY TERMINALS.
SUN...VFR.
MON...MVFR IN RA/SN.
TUE...MVFR IN -RA.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...WIND CHILL ADVISORY UNTIL 9 AM EST FRIDAY FOR NYZ009-036-037-
045-046-057.
&&
$$
SYNOPSIS...RRM
NEAR TERM...MDP/RRM
SHORT TERM...RRM
LONG TERM...DJP
AVIATION...HEDEN
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
738 PM CST THU JAN 24 2013
.DISCUSSION...THE CURRENT CLIPPER SYSTEM IS UNFOLDING PRETTY MUCH
AS EXPECTED. THE STEADIER SNOW IS FALLING ACROSS THE FAR NE
FA...WHERE UP TO 4 INCHES IS STILL EXPECTED. ELSEWHERE...JUST
SCATTERED SNOW SHOWERS WITH MINIMAL ACCUMULATIONS. NO CHANGES
NEEDED TO THE WINTER WEATHER ADVISORY FOR SNOW ACROSS NW
MINNESOTA. THE OTHER CONCERN FOR TONIGHT WILL BE WINDS AND BLOWING
SNOW POTENTIAL WITH THE PASSAGE OF THE COLD FRONT. CURRENT
OBSERVATIONS BEHIND THE COLD FRONT INDICATE WIND SPEEDS 25-35MPH
WITH GUSTS TO 40 MPH. THIS LINES UP WITH WIND PARAMETERS (STRONG
COLD AIR ADVECTION...925MB WINDS AROUND 35 KNTS...AND STRONG 3-HR
PRESSURE RISE). SIMILAR PARAMETERS ARE EXPECTED WITHIN THIS
FA...AND WILL INCREASE FORECASTED WIND SPEEDS TO THESE VALUES
ALONG AND WEST OF THE VALLEY (FOLLOWING THE TIMING OF THE 00Z
RAP). THERE IS LIMITED SNOW TO BLOW AROUND ACROSS MUCH OF THE
REGION...EXCEPT FOR PORTIONS OF THE DEVILS LAKE BASIN INTO THE
CAVALIER AREA WHERE AROUND 14 INCHES OF SNOWPACK EXIST. CURRENT
SOUTH WINDS 15-25 MPH ARE PRODUCING 1-2SM VSBY IN BLOWING
SNOW...MEANING NW WINDS 25-40MPH SHOULD HAVE NO PROBLEM PRODUCING
AT LEAST 1/2SM VSBY IN BLOWING SNOW (CANADIAN BLOWING SNOW MODEL
INDICATES AROUND 20 KNOTS NEEDED TO PRODUCE 1/2SM VSBY IN BLOWING
SNOW). WILL ISSUE A WINTER WEATHER ADVISORY FOR BLOWING SNOW AND
WIND CHILLS FOR THIS AREA. 00Z RAP ALSO SUGGESTS THAT COLD AIR
WILL FILTER INTO THE REGION FASTER THAN ANTICIPATED...AND WITH THE
STRONGER NW WINDS WILL ISSUE A WIND CHILL ADVISORY FOR MUCH OF THE
REGION ALONG AND WEST OF THE VALLEY WHERE THERE IS ONLY MINIMAL
SNOW TO BLOW AROUND.
&&
.AVIATION...CLIPPER SYSTEM WILL MOVE THROUGH THE REGION. THE
GENERAL IDEA FOR CIGS WILL BE MVFR...BECOMING VFR FRIDAY MORNING.
EXPECT SNOW TO MOVE ACROSS THE REGION THIS EVENING. LOWEST
CIGS/VSBY LIKELY WILL BE ON MN SIDE OR RRV (TVF). WINDS WILL SHIFT
TO THE NORTHWEST BY MORNING AND BECOME GUSTY.
&&
.PREV DISCUSSION... /ISSUED 254 PM CST THU JAN 24 2013/
SHORT TERM...
20S OBS SHOW SFC LOW NEAR REGINA SASK WITH PRESSURE FALLS
INDICATING LOW WILL TRACK GENERALLY EAST AND BE NEAR PEMBINA
CLOSE TO 06Z THEN MOVE SOUTHEAST INTO NORTHERN MN OVERNIGHT. MOST
OF THE WIDESPREAD LONG TERM SNOW IS ALONG AND NORTH AND EAST OF
THIS LOW TRACK AND A BIT CLOSER TO THE VORT MAX TRACK WHICH WILL
RUN FROM NEAR YORKTON SASK TO WINNIPEG TO KENORA THEN INTO THE MN
ARROWHEAD. THE LAKE OF THE WOODS REGION IS ON THE SOUTHWESTERN
EDGE OF THIS HEAVIER BAND AND DO EXPECT SOME 3-4 INCH SNOWS
WARROAD-BAUDETTE-WASKISH AREAS. WFO DLH ISSUING ADV/WATCHES FOR
THIS EVENT AND WILL GO ALONG AND ISSUE WINTER WX ADVISORY FOR FAR
NE FCST AREA TONIGHT. REST OF THE FCST AREA TO SEE A BAND OF SNOW
MORE SO WITH THE AND OF WARM ADV WITH 1-2 ALONG CANADIAN BORDER TO
LESS THAN INCH DVL-GFK-PKD SOUTH.
OTHER CONCERN IS WIND LATER TONIGHT. MAIN COLD ADVECTION PUSH NW
ND INTO CNTRL ND WITH WIND POTENTIAL NOT EXTREMELY STRONG IN WRN
FCST AREA. MOST AREAS NOT GETTING MUCH EXCEPT 1-2 RIGHT ALONG
ND/MB BORDER WHERE WINDS WILL BE GUSTY BUT TERRIBLY STRONG. WILL
MENTION SOME BLSN IN GRIDS THRU THE NIGHT IN DVL BASIN INTO NRN
VALLEY DUE TO SOUTH WINDS THIS EVE THEN NORTHWEST LATER TONIGHT
BUT SINCE SNOWFALL ITSELF WILL BE LIMITED DURATION DONT EXPECT
ENOUGH FRESH SNOW FOR THIS WIND TO CAUSE SERIOUS ISSUES ATTM. EVE
SHIFT CAN MONITOR.
TEMPS WILL WARM THIS EVENING...PEAK 06Z-09Z THEN BEGIN TO FALL AS
COLDER AIR RETURNS FROM THE NORTHWEST. TEMPS FRIDAY WILL HOLD
GENERALLY STEADY IN THE SINGLE DIGITS ABOVE/BLO ZERO WITH A STIFF
NORTHWEST WIND.
HIGH PRESSURE TO MOVE IN FRI NIGHT THEN WARM UP BEGINS THIS
WEEKEND AS UPPER FLOW RETURNS TO THE SOUTHWEST ALOFT. THIS MAY
BRING PERIODS OF CLOUDS BUT LIMITED PRECIP.
LONG TERM... /SAT NIGHT THROUGH WED/
12Z RUNS OF LONG TERM MODELS IN MORE DISAGREEMENT THAN YESTERDAYS
12Z RUNS. LONG TERM BEGINS WITH LONG WAVE TROUGH OVER WRN CONUS. GFS
PROGS LWT OVER ROCKIES WHILE THE ECMWF PLACES IT MORE OVER
CALIFORNIA...ALSO WITH A CLOSED LOW. AT THE SFC...GFS HAS A DEEPER
SFC LOW OVER EASTERN ROCKIES THAN ECMWF IS SHOWING. DESPITE
DIFFERENCES...BOTH MODELS SHOW SNOWFALL OVER NORTHERN TIER AS A
NORTHERN WAVE MOVES ACROSS SRN CANADA. FEEL COMFORTABLE WITH CHANCE
POPS ACROSS FOR MONDAY. GFS THEN LIFTS CNTRL PLAIN LOW INTO WRN
IA/SWRN MN ON MON NIGHT...SETTING UP DEFORMATION ZONE OVER MY CWA.
YESTERDAY THIS FEATURE WAS FURTHER SOUTHEAST AND MAINLY IMPACTED
OUR SOUTHEASTERN ZONES. ECMWF NOT DOING MUCH WITH THE SFC LOW AND IS
STRONGER WITH THE NORTHERN WAVE WHILE THE CLOSED LOW REMAINS JUST
WEST OF OLYMPIC CALIFORNIA. THUS NOT A WHOLE LOT OF CONFIDENCE WITH
THE GFS SOLUTION AS IT HAS DIVERGED CONSIDERABLY FROM 12Z YESTERDAY.
WILL KEEP HIGH CHANCE POPS IN THE SOUTHEAST...BUT NOT RAISE TO
LIKELIES AS THE NEWER CONSALL GUIDANCE IS SUGGESTING. MOVING INTO
TUE...ECMWF CUTS OFF UPPER LOW AND DOES STRENGTHEN SFC LOW OVER
UPPER GREAT LAKES...IN GENERAL AGREEMENT WITH GFS LOCATION THAT IS
BASED ON BROADER TROUGHING THROUGHOUT THE CNTRL US. WILL KEEP
CONSALL POPS REALIZING IF ECMWF IS CORRECT...LOW WILL PULL OUT
QUICKER AND MOVE PRECIP OUT OF EASTERN ZONES BY TUE EVENING. MODELS
ACTUALLY IN BETTER AGREEMENT FOR TUE NIGHT INTO WED AS NORTHERLY
FLOW RETURNS...SETTING UP NEXT ARCTIC HIGH TO DROP IN ON WED. COLD
AIR THEN REMAINS IN PLACE FOR REST OF THE WORK WEEK. SHOULD SEE WELL
BELOW NORMAL TEMPS FROM WED THROUGH FRI.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WIND CHILL ADVISORY FROM 4 AM TO NOON CST FRIDAY FOR NDZ016-
027>030-038-039.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST FRIDAY
FOR NDZ006>008-014-015-024-026-054.
MN...WIND CHILL ADVISORY FROM 4 AM TO NOON CST FRIDAY FOR MNZ001>004-
007.
WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR MNZ005-006-009-
017.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
131 PM EST WED JAN 23 2013
.SYNOPSIS...
DISTURBANCE PRODUCES SNOW LATE THIS AFTERNOON AND TONIGHT...MAINLY
NORTH AND EAST. ANOTHER DISTURBANCE PRODUCES SNOW FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
10 AM UPDATE...NO SIGNIFICANT CHANGES. ALLOWED WIND CHILL ADVISORY
TO EXPIRE AT 10 AM.
600AM UPDATE...
AFTER FURTHER INTERROGATION OF 06Z NAM AND LATEST RUC AND HI RES
IN HOUSE MDLS...ELECTED TO TIGHTEN UP POP GRADIENT LATE THIS AFTN
AND EARLY EVE...SETTING UP ALONG AND N OF TRACK OF CLIPPER. THIS
LOOKS TO SET UP N OF I64 CORRIDOR...CLOSER TO A ATH-PKB-CKB-EKN
LINE. WILL STILL ALLOW FOR SOME LKLY INTO CRW AS CLIPPER EXITS AND
WINDS ALOFT TURN MORE NW AND UPSLOPE BEGINS WITH LAKE MICHIGAN
CONTRIBUTION. TWEAKED SN ACCUMS WITH THIS IN MIND...WHICH STILL
ALLOWED FOR A COATING ACROSS CRW...WITH LITTLE CHANGE FURTHER N.
THINK HTS SEES LITTLE IF ANY FOR HTS.
PREVIOUS DISCUSSION BELOW...
WILL BE TRACKING A CLIPPER TYPE SYS TO ROLL THRU LATER TDY AND
THIS EVE. STILL SOME MDL DISCREPANCIES REGARDING TRACK AND THUS
QPF AXIS WITH THIS...WITH NAM12 AND HI RES WRF MDLS CONT TO BE ON
THE S EDGE OF THE ENVELOPE. GFS AND ECWMF MAINTAIN MOST OF QPF
ACROSS SE OH AND THE N WV. REGIONAL CMC AND LATEST SREF SEEM TO BE
A GOOD COMPROMISE...PLACING BULK OF QPF ACROSS THE CENTRAL AND N
LOWLANDS/MTNS AND IN NORTHERN PORTIONS OF SE OH. JUST GLANCED AT
06Z NAM12 AND IT IS MORE IN LINE WITH COMPROMISED SOLUTION.
CONSIDERABLE TIMING DIFF EXIST AS WELL. THINK INITIAL ECHOES WILL
BE VIRGA AND MAY TAKE A BIT TO MOISTEN UP THE LLVL COLUMN ENOUGH
TO SURVIVE THE TRIP TO THE SFC. WILL CARRY LKLY POPS ACROSS
NORTHERN PARTS OF SE OH BY AFTER 21Z AND INTO N LOWLANDS AFTER
00Z...OOZING S INTO KANAWHA VALLEY AND S PLATEAU BY 03Z. THINK NE
KY INTO COAL FIELDS AND SW VA ESCAPE MUCH OF THE ACTION. HTS TOUGH
CALL BUT THINK THEY ESCAPE MUCH OF THE -SN AS WELL. WILL GO WITH
SUGAR COATINGS UP TO HALF AN INCH IN SE OH...AND KANAWHA VALLEY TO
INCLUDE CRW AREA. WILL ALLOW FOR UP TO AN INCH IN N LOWLANDS WITH
2 TO 3 IN THE MTNS BY 12Z...WITH THE HIGHEST IN THE C AND N MTNS.
THE MTN TOTAL INCLUDES SOME UPSLOPE/LAKE CONTRIBUTIONS AFTER 09Z.
LOW QPF EVENT BUT RELATIVELY HIGH SLR.
TEMPS ARND HTS-CRW METRO AREAS SLOW TO FALL OVERNIGHT DUE TO PESKY
SFC WIND AND CLDS. THINK SOME DECOUPLING WILL BE REALIZED IN THE
NEXT COUPLE HRS ALONG WITH LOSS OF CLDS FOR A FALL INTO LWR TEENS.
WILL LET WIND CHILL ADV CONT FOR N MTNS WITH EMPHASIS IN THE HIGHER
ELEVATIONS/RIDGES. INHERITED MAXT GRID LOOKED GOOD AND ONLY MINOR
TWEAKS MADE. SHOULD GET NE KY...S WV AND SW VA INTO THE MID AND UPR
20S WITH LWR 20S SE OH AND N WV. ALLOW MODEST RECOVERY IN MTNS AS
WELL FROM YESTERDAYS NUMBERS. HEDGED INHERITED MINT GRID UP TONIGHT
ACROSS THE MTNS BASED ON EXPECTED PCPN/CLDS.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
MODELS SHOW SOME LINGERING LOW LEVEL MOISTURE ON THURSDAY WITH LAKE
PLUMES ACROSS THE AREA. WITH COLD AIR ADVECTION IN THE MORNING AND
SOME UPSLOPE...WILL KEEP SOME POPS...MORE SO IN THE MOUNTAINS.
MODELS CONTINUE TO STRUGGLE WITH SYSTEM ON FRIDAY. MODELS NOW SEEM
TO AGREE ON TIMING OF SYSTEM...BUT PRECIPITATION AMOUNTS AND
PLACEMENT OF PRECIPITATION VARY CONSIDERABLY. WILL STAY CLOSE TO
PREVIOUS FORECAST FOR CONSISTENCY...WHICH IS SUPPORTED BY SEVERAL
MODELS. THIS WOULD GIVE 1 TO 2 INCHES OF SNOW. THIS IS A GOOD MIDDLE
GROUND AS SOME MODELS HAVE LESS AND ECMWF HAS MUCH MORE.
&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
SNOW SHOWERS LINGER PARTICULARLY IN THE MOUNTAINS ON FRIDAY NIGHT.
THE REGION DRIES OUT FOR THE WEEKEND BEFORE A WARMER AIR MASS
MOVES THROUGH THE REGION EARLY NEXT WEEK BRINGING RAIN TO THE REGION.
A SHARP COLD FRONT MOVES THROUGH TOWARDS MID WEEK BRINGING A
STRONGER FRONT THROUGH THE REGION WITH SNOW LEVELS DROPPING IN ITS
WAKE.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
18Z WEDNESDAY THRU 18Z THURSDAY...
VFR CEILINGS REMAINDER OF AFTERNOON WITH APPROACH OF A CLIPPER TYPE
SYSTEM. HAVE MVFR CIGS WITH -SN DEVELOPING 22Z TO 00Z ACROSS
SOUTHEASTERN OH AND NORTHERN WV...SPREADING INTO CENTRAL WV BY 03Z.
CODED UP MVFR TO IFR VSBY...WITH IFR VSBY CONFINED TO
KPKB...KCKB...KEKN.
AFTER 08Z...CONDITIONS SLOWLY IMPROVING FROM NORTHWEST TO
SOUTHEAST...BUT STILL MAINLY MVFR CEILINGS...WITH LOCAL IFR IN LIGHT
SNOW CENTRAL WV AND MOUNTAINS THRU 12Z.
AFTER 12Z...SNOW SHOWERS ENDING BY 18Z IN MOUNTAINS...BECOMING VFR
CEILINGS WEST AND NORTH PORTIONS OF AREA.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z THURSDAY...
FORECAST CONFIDENCE: HIGH EARLY...MEDIUM AFTER 18Z.
ALTERNATE SCENARIOS: TIMING OF -SN COULD VARY...ALSO EXTENT OF -SN
AND THUS MVFR TO IFR CONDITIONS IN QUESTION TOWARD
KCRW...AND KBKW.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00
CRW CONSISTENCY H H H H H H H H L L M M
HTS CONSISTENCY H H H H H H H H H H H L
BKW CONSISTENCY H H H H H H H H H H M L
EKN CONSISTENCY H H H H H L L L M M M M
PKB CONSISTENCY H H H H H L L M M M L L
CKB CONSISTENCY H H H H H L L L M M M L
AFTER 18Z THURSDAY...
IFR CONDITIONS POSSIBLE FRIDAY WITH SNOW...AND FRIDAY NIGHT INTO
SATURDAY IN THE MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...JMV
SHORT TERM...RPY
LONG TERM...JW
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1013 AM EST WED JAN 23 2013
.SYNOPSIS...
DISTURBANCE PRODUCES SNOW LATE THIS AFTERNOON AND TONIGHT. ANOTHER
DISTURBANCE PRODUCES SNOW FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
10 AM UPDATE...NO SIGNIFICANT CHANGES. ALLOWED WIND CHILL ADVISORY
TO EXPIRE AT 10 AM.
600AM UPDATE...
AFTER FURTHER INTERROGATION OF 06Z NAM AND LATEST RUC AND HI RES
IN HOUSE MDLS...ELECTED TO TIGHTEN UP POP GRADIENT LATE THIS AFTN
AND EARLY EVE...SETTING UP ALONG AND N OF TRACK OF CLIPPER. THIS
LOOKS TO SET UP N OF I64 CORRIDOR...CLOSER TO A ATH-PKB-CKB-EKN
LINE. WILL STILL ALLOW FOR SOME LKLY INTO CRW AS CLIPPER EXITS AND
WINDS ALOFT TURN MORE NW AND UPSLOPE BEGINS WITH LAKE MICHIGAN
CONTRIBUTION. TWEAKED SN ACCUMS WITH THIS IN MIND...WHICH STILL
ALLOWED FOR A COATING ACROSS CRW...WITH LITTLE CHANGE FURTHER N.
THINK HTS SEES LITTLE IF ANY FOR HTS.
PREVIOUS DISCUSSION BELOW...
WILL BE TRACKING A CLIPPER TYPE SYS TO ROLL THRU LATER TDY AND
THIS EVE. STILL SOME MDL DISCREPANCIES REGARDING TRACK AND THUS
QPF AXIS WITH THIS...WITH NAM12 AND HI RES WRF MDLS CONT TO BE ON
THE S EDGE OF THE ENVELOPE. GFS AND ECWMF MAINTAIN MOST OF QPF
ACROSS SE OH AND THE N WV. REGIONAL CMC AND LATEST SREF SEEM TO BE
A GOOD COMPROMISE...PLACING BULK OF QPF ACROSS THE CENTRAL AND N
LOWLANDS/MTNS AND IN NORTHERN PORTIONS OF SE OH. JUST GLANCED AT
06Z NAM12 AND IT IS MORE IN LINE WITH COMPROMISED SOLUTION.
CONSIDERABLE TIMING DIFF EXIST AS WELL. THINK INITIAL ECHOES WILL
BE VIRGA AND MAY TAKE A BIT TO MOISTEN UP THE LLVL COLUMN ENOUGH
TO SURVIVE THE TRIP TO THE SFC. WILL CARRY LKLY POPS ACROSS
NORTHERN PARTS OF SE OH BY AFTER 21Z AND INTO N LOWLANDS AFTER
00Z...OOZING S INTO KANAWHA VALLEY AND S PLATEAU BY 03Z. THINK NE
KY INTO COAL FIELDS AND SW VA ESCAPE MUCH OF THE ACTION. HTS TOUGH
CALL BUT THINK THEY ESCAPE MUCH OF THE -SN AS WELL. WILL GO WITH
SUGAR COATINGS UP TO HALF AN INCH IN SE OH...AND KANAWHA VALLEY TO
INCLUDE CRW AREA. WILL ALLOW FOR UP TO AN INCH IN N LOWLANDS WITH
2 TO 3 IN THE MTNS BY 12Z...WITH THE HIGHEST IN THE C AND N MTNS.
THE MTN TOTAL INCLUDES SOME UPSLOPE/LAKE CONTRIBUTIONS AFTER 09Z.
LOW QPF EVENT BUT RELATIVELY HIGH SLR.
TEMPS ARND HTS-CRW METRO AREAS SLOW TO FALL OVERNIGHT DUE TO PESKY
SFC WIND AND CLDS. THINK SOME DECOUPLING WILL BE REALIZED IN THE
NEXT COUPLE HRS ALONG WITH LOSS OF CLDS FOR A FALL INTO LWR TEENS.
WILL LET WIND CHILL ADV CONT FOR N MTNS WITH EMPHASIS IN THE HIGHER
ELEVATIONS/RIDGES. INHERITED MAXT GRID LOOKED GOOD AND ONLY MINOR
TWEAKS MADE. SHOULD GET NE KY...S WV AND SW VA INTO THE MID AND UPR
20S WITH LWR 20S SE OH AND N WV. ALLOW MODEST RECOVERY IN MTNS AS
WELL FROM YESTERDAYS NUMBERS. HEDGED INHERITED MINT GRID UP TONIGHT
ACROSS THE MTNS BASED ON EXPECTED PCPN/CLDS.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
MODELS SHOW SOME LINGERING LOW LEVEL MOISTURE ON THURSDAY WITH LAKE
PLUMES ACROSS THE AREA. WITH COLD AIR ADVECTION IN THE MORNING AND
SOME UPSLOPE...WILL KEEP SOME POPS...MORE SO IN THE MOUNTAINS.
MODELS CONTINUE TO STRUGGLE WITH SYSTEM ON FRIDAY. MODELS NOW SEEM
TO AGREE ON TIMING OF SYSTEM...BUT PRECIPITATION AMOUNTS AND
PLACEMENT OF PRECIPITATION VARY CONSIDERABLY. WILL STAY CLOSE TO
PREVIOUS FORECAST FOR CONSISTENCY...WHICH IS SUPPORTED BY SEVERAL
MODELS. THIS WOULD GIVE 1 TO 2 INCHES OF SNOW. THIS IS A GOOD MIDDLE
GROUND AS SOME MODELS HAVE LESS AND ECMWF HAS MUCH MORE.
&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
SNOW SHOWERS LINGER PARTICULARLY IN THE MOUNTAINS ON FRIDAY NIGHT.
THE REGION DRIES OUT FOR THE WEEKEND BEFORE A WARMER AIR MASS
MOVES THROUGH THE REGION EARLY NEXT WEEK BRINGING RAIN TO THE REGION.
A SHARP COLD FRONT MOVES THROUGH TOWARDS MID WEEK BRINGING A
STRONGER FRONT THROUGH THE REGION WITH SNOW LEVELS DROPPING IN ITS
WAKE.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
15Z WEDNESDAY THRU 12Z THURSDAY...
VFR CEILINGS OVERSPREAD THE AREA FROM THE WEST THRU 20Z WITH
APPROACH OF A CLIPPER TYPE SYSTEM. HAVE MVFR CIGS WITH -SN
DEVELOPING LATE IN AFTN AND EARLY EVE ACROSS SE OH AND N
WV...SPREADING INTO C WV BY 03Z TO AFFECT REMAINDER OF N TERMINALS.
CODED UP MVFR TO IFR VSBY...WITH IFR VSBY CONFINED TO
KPKB...KCKB...KEKN...AND KCRW.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z THURSDAY...
FORECAST CONFIDENCE: HIGH EARLY...MEDIUM AFTER 18Z.
ALTERNATE SCENARIOS: TIMING OF -SN COULD VARY...ALSO EXTENT OF -SN
AND THUS MVFR TO IFR CONDITIONS IN QUESTION TOWARD
KCRW...AND KBKW.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
EST 1HRLY 09 10 11 12 13 14 15 16 17 18 19 20
CRW CONSISTENCY H H H H H H H H H H L L
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H L L L
PKB CONSISTENCY H H H H H H H H H M L M
CKB CONSISTENCY H H H H H H H H H M L L
AFTER 12Z THURSDAY...
IFR CONDITIONS POSSIBLE FRIDAY WITH SNOW...AND FRIDAY NIGHT INTO
SATURDAY IN THE MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...JMV
SHORT TERM...RPY
LONG TERM...JW
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
607 AM EST WED JAN 23 2013
.SYNOPSIS...
DISTURBANCE PRODUCES SNOW LATE THIS AFTERNOON AND TONIGHT. ANOTHER
DISTURBANCE PRODUCES SNOW FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
600AM UPDATE...
AFTER FURTHER INTERROGATION OF 06Z NAM AND LATEST RUC AND HI RES
IN HOUSE MDLS...ELECTED TO TIGHTEN UP POP GRADIENT LATE THIS AFTN
AND EARLY EVE...SETTING UP ALONG AND N OF TRACK OF CLIPPER. THIS
LOOKS TO SET UP N OF I64 CORRIDOR...CLOSER TO A ATH-PKB-CKB-EKN
LINE. WILL STILL ALLOW FOR SOME LKLY INTO CRW AS CLIPPER EXITS AND
WINDS ALOFT TURN MORE NW AND UPSLOPE BEGINS WITH LAKE MICHIGAN
CONTRIBUTION. TWEAKED SN ACCUMS WITH THIS IN MIND...WHICH STILL
ALLOWED FOR A COATING ACROSS CRW...WITH LITTLE CHANGE FURTHER N.
THINK HTS SEES LITTLE IF ANY FOR HTS.
PREVIOUS DISCUSSION BELOW...
WILL BE TRACKING A CLIPPER TYPE SYS TO ROLL THRU LATER TDY AND
THIS EVE. STILL SOME MDL DISCREPANCIES REGARDING TRACK AND THUS
QPF AXIS WITH THIS...WITH NAM12 AND HI RES WRF MDLS CONT TO BE ON
THE S EDGE OF THE ENVELOPE. GFS AND ECWMF MAINTAIN MOST OF QPF
ACROSS SE OH AND THE N WV. REGIONAL CMC AND LATEST SREF SEEM TO BE
A GOOD COMPROMISE...PLACING BULK OF QPF ACROSS THE CENTRAL AND N
LOWLANDS/MTNS AND IN NORTHERN PORTIONS OF SE OH. JUST GLANCED AT
06Z NAM12 AND IT IS MORE IN LINE WITH COMPROMISED SOLUTION.
CONSIDERABLE TIMING DIFF EXIST AS WELL. THINK INITIAL ECHOES WILL
BE VIRGA AND MAY TAKE A BIT TO MOISTEN UP THE LLVL COLUMN ENOUGH
TO SURVIVE THE TRIP TO THE SFC. WILL CARRY LKLY POPS ACROSS
NORTHERN PARTS OF SE OH BY AFTER 21Z AND INTO N LOWLANDS AFTER
00Z...OOZING S INTO KANAWHA VALLEY AND S PLATEAU BY 03Z. THINK NE
KY INTO COAL FIELDS AND SW VA ESCAPE MUCH OF THE ACTION. HTS TOUGH
CALL BUT THINK THEY ESCAPE MUCH OF THE -SN AS WELL. WILL GO WITH
SUGAR COATINGS UP TO HALF AN INCH IN SE OH...AND KANAWHA VALLEY TO
INCLUDE CRW AREA. WILL ALLOW FOR UP TO AN INCH IN N LOWLANDS WITH
2 TO 3 IN THE MTNS BY 12Z...WITH THE HIGHEST IN THE C AND N MTNS.
THE MTN TOTAL INCLUDES SOME UPSLOPE/LAKE CONTRIBUTIONS AFTER 09Z.
LOW QPF EVENT BUT RELATIVELY HIGH SLR.
TEMPS ARND HTS-CRW METRO AREAS SLOW TO FALL OVERNIGHT DUE TO PESKY
SFC WIND AND CLDS. THINK SOME DECOUPLING WILL BE REALIZED IN THE
NEXT COUPLE HRS ALONG WITH LOSS OF CLDS FOR A FALL INTO LWR TEENS.
WILL LET WIND CHILL ADV CONT FOR N MTNS WITH EMPHASIS IN THE HIGHER
ELEVATIONS/RIDGES. INHERITED MAXT GRID LOOKED GOOD AND ONLY MINOR
TWEAKS MADE. SHOULD GET NE KY...S WV AND SW VA INTO THE MID AND UPR
20S WITH LWR 20S SE OH AND N WV. ALLOW MODEST RECOVERY IN MTNS AS
WELL FROM YESTERDAYS NUMBERS. HEDGED INHERITED MINT GRID UP TONIGHT
ACROSS THE MTNS BASED ON EXPECTED PCPN/CLDS.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
MODELS SHOW SOME LINGERING LOW LEVEL MOISTURE ON THURSDAY WITH LAKE
PLUMES ACROSS THE AREA. WITH COLD AIR ADVECTION IN THE MORNING AND
SOME UPSLOPE...WILL KEEP SOME POPS...MORE SO IN THE MOUNTAINS.
MODELS CONTINUE TO STRUGGLE WITH SYSTEM ON FRIDAY. MODELS NOW SEEM
TO AGREE ON TIMING OF SYSTEM...BUT PRECIPITATION AMOUNTS AND
PLACEMENT OF PRECIPITATION VARY CONSIDERABLY. WILL STAY CLOSE TO
PREVIOUS FORECAST FOR CONSISTENCY...WHICH IS SUPPORTED BY SEVERAL
MODELS. THIS WOULD GIVE 1 TO 2 INCHES OF SNOW. THIS IS A GOOD MIDDLE
GROUND AS SOME MODELS HAVE LESS AND ECMWF HAS MUCH MORE.
&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
SNOW SHOWERS LINGER PARTICULARLY IN THE MOUNTAINS ON FRIDAY NIGHT.
THE REGION DRIES OUT FOR THE WEEKEND BEFORE A WARMER AIR MASS
MOVES THROUGH THE REGION EARLY NEXT WEEK BRINGING RAIN TO THE REGION.
A SHARP COLD FRONT MOVES THROUGH TOWARDS MID WEEK BRINGING A
STRONGER FRONT THROUGH THE REGION WITH SNOW LEVELS DROPPING IN ITS
WAKE.
&&
.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
SCT TO BKN 9 TO 12KFT PASSING THRU THIS MORNING. LIGHT WEST WINDS
OUTSIDE OF THE MTNS...WITH GUSTY WINDS TO 20 KTS CONT ACROSS THE
HIGH TERRAIN RIDGETOPS.
CLOUD BASES GRADUALLY LWR AND THICKEN AFTER 18Z WITH APPROACH OF A
CLIPPER TYPE SYSTEM. HAVE MVFR CIGS WITH -SN DEVELOPING LATE IN AFTN
AND EARLY EVE ACROSS SE OH AND N WV...SPREADING INTO C WV BY 03Z
TO AFFECT REMAINDER OF N TERMINALS. CODED UP MVFR TO IFR
VSBY...WITH IFR VSBY CONFINED TO KPKB...KCKB...KEKN...AND KCRW.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z THURSDAY...
FORECAST CONFIDENCE: HIGH EARLY...MEDIUM AFTER 18Z.
ALTERNATE SCENARIOS: TIMING OF -SN COULD VARY...ALSO EXTENT OF -SN
AND THUS MVFR TO IFR CONDITIONS IN QUESTION TOWARD
KCRW...AND KBKW.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EST 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 12Z THURSDAY...
IFR CONDITIONS POSSIBLE FRIDAY WITH SNOW...AND FRIDAY NIGHT INTO
SATURDAY IN THE MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR WVZ038-
046-047.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...RPY/30
NEAR TERM...30
SHORT TERM...RPY
LONG TERM...JW
AVIATION...30
AREA FORECAST DISCUSSION
NWS NORMAN OK
1128 PM CST TUE JAN 22 2013
.AVIATION...
THERE REMAINS SOME SIGNAL FOR SOME FOG ACROSS PORTIONS OF THE
AREA... ESPECIALLY IN THE SOUTHWEST AND CENTRAL PORTION OF THE
FORECAST AREA. HRRR WOULD SUGGEST SOME LOW VISIBILITIES... BUT
HAVE SO FAR ONLY BROUGHT VISIBILITIES DOWN TO 3SM TO 4SM. WILL
HAVE TO CONTINUE TO WATCH TRENDS OVERNIGHT.
&&
.PREV DISCUSSION... /ISSUED 920 PM CST TUE JAN 22 2013/
UPDATE...
MAIN POINT OF FOCUS OVERNIGHT IS THE POSSIBILITY FOR FOG
DEVELOPMENT LATE TONIGHT ACROSS PARTS OF THE AREA. HIGH RES HRRR
CONT TO INDICATE FOG DEVELOPING TOWARD SUNRISE ACROSS CENTRAL INTO
SOUTHWEST OKLAHOMA AND WESTERN NORTH TEXAS AND WILL KEEP A MENTION
OF THIS IN THE ZONES. IF IT DOES DEVELOP COULD BECOME DENSE... BUT
FOR NOW WITH UNCERTAINTY REMAINING WILL LEAVE JUST PATCHY WORDING
IN THE FORECAST. FARTHER EAST ACROSS SOUTH CENTRAL INTO SOUTHEAST
OKLAHOMA LIKELY SOME STRATUS WILL DEVELOP AFTER MIDNIGHT.
OTHERWISE WEAK SFC BOUNDARY WILL REMAIN ACROSS NORTHERN OKLAHOMA
WITH DRIER AND COOLER CONDITIONS.
PREV DISCUSSION... /ISSUED 544 PM CST TUE JAN 22 2013/
AVIATION...
A WEAK SURFACE FRONT WILL MOVE INTO THE AREA BUT THEN LIFT BACK
NORTH. WINDS MAY BRIEFLY SHIFT TO INCLUDE A NORTHERLY COMPONENT
FOR A FEW HOURS BEFORE SOUTHERLIES RETURN. REGARDLESS... WINDS
SHOULD BE LIGHT. THERE IS SOME SIGNAL /ALBEIT INCONSISTENT/ FOR
FOG AND TIME-HEIGHT CROSS SECTION OF HUMIDITY SUGGESTS SOME
POTENTIAL FOR LOW CLOUDS ALTHOUGH MODEL MOS GUIDANCE DOES NOT
INCLUDE LOW CLOUDS. HAVE INCLUDED A TEMPO GROUP WITH 4SM FG AT
SOME OF THE SITES AND WILL CONTINUE TO WATCH TRENDS THIS EVENING.
PREV DISCUSSION... /ISSUED 412 PM CST TUE JAN 22 2013/
DISCUSSION...
TEMPS HAVE CLIMBED INTO THE 50S AND 60S THIS AFTERNOON UNDER THE
INFLUENCE OF SOUTHERLY LOW LEVEL FLOW. THIS LIGHT SOUTHERLY FLOW
WILL CONTINUE TO INCREASE DEWPOINTS ACROSS THE SOUTHERN HALF OF
THE FA THROUGH TONIGHT. SOME STRATUS MAY DEVELOP ACROSS SE
OK...BUT WEST OF THIS FROM SW/CENTRAL OK THROUGH PORTIONS OF
WESTERN N TX FOG STILL APPEARS POSSIBLE. IT IS STILL UNCLEAR
HOW LOW VISBYS WILL DROP AND HOW WIDESPREAD THE FOG WILL
BECOME. THIS WILL DEPEND ON HOW MUCH LOW LEVEL MOISTURE
ADVECTION ACTUALLY OCCURS THROUGH THE OVERNIGHT HOURS. THE WARMEST
TEMPS OF THE WEEK ARE EXPECTED TOMORROW AS AN UPPER RIDGE MOVES
OVER THE ROCKIES AND WSW DOWNSLOPE FLOW IMPACTS THE REGION.
THE FORECAST HAS CHANGED A BIT FOR THURSDAY WITH MOST MODELS
NOW INDICATING A COLD FRONT WILL WORK ITS WAY INTO CENTRAL OK
THURS MORN AS A STRONG SHORTWAVE TROUGH DIGS SOUTH OVER THE GREAT
LAKES. WITH THE SURFACE LOW FURTHER SOUTH THAN ORIGINALLY
ANTICIPATED (NEAR THE RED RIVER)...THIS WILL KEEP COOLER TEMPS IN
PLACE FOR MOST OF THE REGION AND ONLY AN ELEVATED FIRE WEATHER
THREAT CONFINED TO THE EXTREME SW. DRIZZLE/SHOWERS MAY DEVELOP
MAINLY ACROSS CENTRAL...NORTHERN...AND EASTERN OK THURSDAY WHERE
WEAK ISENTROPIC ASCENT AND ENOUGH MOISTURE WILL RESIDE. MOST
LOCATIONS WILL REMAIN DRY. YET ANOTHER SHORTWAVE TROUGH WILL DIVE
INTO THE UPPER MIDWEST FRI MORNING RESULTING IN LOW LEVEL CAA
THROUGH AT LEAST FRI EVE KEEPING TEMPS NEAR OR BELOW NORMAL.
FINALLY...BY SUNDAY...CONFIDENCE IS INCREASING WITH REGARDS TO
BOTH INCREASING LOW LEVEL MOISTURE ADVECTION SAT-SUN AHEAD OF AN
APPROACHING SHORTWAVE TROUGH THAT WILL MOVE OVER THE PANHANDLE
LATE SATURDAY NIGHT. HAVE INCREASED POPS A BIT FOR NORTHERN
OK...BUT RAIN CHANCES WILL LIKELY BE BRIEF AS THIS WAVE QUICKLY
EXITS THE REGION.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 35 64 37 51 / 0 0 0 10
HOBART OK 32 65 37 50 / 0 0 0 10
WICHITA FALLS TX 39 71 43 63 / 0 0 0 0
GAGE OK 25 63 27 42 / 0 0 0 10
PONCA CITY OK 26 59 27 38 / 0 0 0 20
DURANT OK 45 70 47 67 / 0 0 0 10
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
300 AM CST WED JAN 23 2013
.DISCUSSION.../ISSUED AT 300 AM CST/
COLD FRONT WILL CONTINUE TO DROP SOUTHEAST ACROSS CWA THIS MORNING
WITH BREEZY NORTHWEST WINDS BEHIND THIS FRONT TODAY. COLD AIR
ADVECTION LAGGING A BIT BEHIND THIS FRONT...BUT SHOULD PUSH IN BY
AFTERNOON. SO HIGH TEMPERATURES LIKELY TO OCCUR THIS
MORNING...BEFORE HOLDING STEADY OR FALLING A BIT THIS
AFTERNOON...ESPECIALLY NORTHEAST CWA. PLENTY OF HIGH CLOUDS
TODAY...SO PARTLY SUNNY AT BEST. MODELS MORE IN AGREEMENT WITH COLD
PUSH TONIGHT...ALTHOUGH MAV APPEARS TO BE WAY OVERDOING COLD
AIR...ESPECIALLY WITH SOME HIGH CLOUDS PERSISTING ACROSS CWA. STILL
WILL BE QUITE COLD AND WILL LOWER MINS A GOOD 5 DEGREES MOST PLACES.
IF SKIES DO CLEAR MORE THAN EXPECTED...THAN NORTHEAST CWA COULD
EASILY DROP TO 15 BELOW TONIGHT. WITH WINDS EXPECTED TO BE A BIT
BREEZY THIS EVENING...WILL ISSUE A WIND CHILL ADVISORY ACROSS
NORTHEAST CWA FOR TONIGHT INTO EARLY THURSDAY MORNING...AS WIND
CHILLS DROP TO 20 BELOW TO 30 BELOW.
WILL REMAIN COLD ON THURSDAY WITH LOW LEVEL SOUTHEAST OFF OF ARCTIC
HIGH NOT TOO CONDUCIVE TO GOOD WARMING. IN FACT HIGH TEMPERATURES
MAY OCCUR THURSDAY EVENING AS TEMPERATURES RISE DURING NIGHT AS LOW
LEVEL FLOWS BECOMES SOUTH TO SOUTHWEST AHEAD OF NEXT WAVE. COULD SEE
A LITTLE LIGHT SNOW OR FLURRIES AHEAD OF THE ASSOCIATED WARM FRONT
OVER SOUTHWEST MINNESOTA THURSDAY NIGHT...AND WILL KEEP A SMALL
CHANCE IN FORECAST FOR THAT AREA.
ANOTHER SHOT OF COLD AIR FRIDAY BEHIND SHORT WAVE...SO ONCE
AGAIN...HIGH TEMPERATURES MAY OCCUR EARLY...ESPECIALLY NORTHEAST CWA
WHERE MAIN BRUNT OF COLD AIR ADVECTION WILL OCCUR.
SATURDAY MORNING WILL START OUT WITH SUB ZERO LOWS ACROSS EASTERN
CWA WITH HIGHS STRUGGLING THROUGH THE TEENS WITH LOW LEVEL SOUTHEAST
FLOW. WESTERN CWA WILL WARM MORE WITH HIGHS APPROACHING 30 ACROSS
THE SOUTHWEST CWA.
STRONGER WARMING ON SUNDAY WITH HIGHS ABOVE NORMAL MOST PLACES.
WAVE PUSHING EAST ACROSS CENTRAL PLAINS MAY GRAZE THE FAR SOUTHEAST
CWA ON SUNDAY AND WILL KEEP SMALL CHANCE OF LIGHT RAIN OR SNOW THERE
DURING THE DAY. WILL REMAIN MILD ON MONDAY AHEAD OF NEXT SYSTEM.
MODELS STILL DIVERGE A BIT ON SYSTEM FOR NEXT TUESDAY...WITH GFS
MUCH STRONGER THAN ECMWF. STILL EC DOES SET UP DECENT OVER RUNNING
AS ARCTIC FRONT SAGS THROUGH CWA MONDAY NIGHT...WITH SOUTHWEST FLOW
ALOFT PERSISTING ACROSS CWA ON TUESDAY. THIS SHOULD SET UP A DECENT
MID LEVEL FRONT ACROSS THE NORTHERN PLAINS. EXACT LOCATION STILL
SKETCHY...BUT WILL UP POPS TO CHANCE FOR TUESDAY. WOULD NOT BE
SURPRISED IF SOME PART OF THE CWA SEES A BAND OF 2 TO 4 INCH SNOW ON
TUESDAY WITH THIS SETUP.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
AS EXPECTED...THERE IS STILL SOME MVFR CEILINGS LINGERING IN THE
EXTREME EASTERN SECTION OF EAST CENTRAL SD AND THROUGH SOUTHWEST MN.
BOTH THE LATEST NAM12 AND RUC13 MODELS ARE IN GOOD AGREEMENT IN
SLOWLY MOVING THE MVFR STRATUS EASTWARD ACROSS SOUTHWEST MN THROUGH
09Z TONIGHT. BUT THEN THE STRATUS MAY HANG UP NEAR THE MARSHALL AND
WINDOM MINNESOTA AREAS AS WINDS JUST OFF THE SURFACE SHIFT NORTHWEST
ALONG A COLD FRONT. THEREFORE MVFR CONDITIONS COULD LINGER IN OUR
EXTREME NORTHEAST ZONES WELL INTO WEDNESDAY MORNING. OTHERWISE
CONDITIONS SHOULD BE VFR FOR THE REST OF THE SIOUX FALLS FORECAST
AREA THROUGH WEDNESDAY EVENING. THERE IS A HIGHER DECK OF STRATUS
NEAR 4000 TO 5000 FT AGL TO THE WEST OF THE MVFR CEILINGS EXTENDING
FROM NEAR HURON SD...TO MOST OF NORTHWEST IA. HOWEVER VARIOUS MODELS
ALSO PROJECT THIS HIGHER BASED STRATUS TO EDGE EASTWARD THROUGH THE
REST OF THE NIGHT ALONG A WNW WIND COMPONENT IN THAT LAYER. SO THAT
SEEMS LOGICAL. AS BRIEFLY MENTIONED ABOVE...THERE WILL BE A COLD
FRONTAL PASSAGE ACROSS THE FORECAST AREA LATE TONIGHT AND VERY EARLY
WEDNESDAY. THEREFORE SURFACE WINDS WILL BE NORTH TO NORTHWEST ON
WEDNESDAY AND A BIT BREEZY. HOWEVER MOST GUSTS SHOULD STAY BELOW 25
KNOTS. /MJF
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...WIND CHILL ADVISORY FROM 6 PM THIS EVENING TO 8 AM CST THURSDAY
FOR IAZ002-003-014.
MN...WIND CHILL ADVISORY FROM 6 PM THIS EVENING TO 8 AM CST THURSDAY
FOR MNZ071-072-080-081-089-090-097.
NE...NONE.
SD...WIND CHILL ADVISORY FROM 6 PM THIS EVENING TO 8 AM CST THURSDAY
FOR SDZ040.
&&
$$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1049 PM CST TUE JAN 22 2013
.DISCUSSION.../ISSUED AT 925 PM CST/
EARLIER FORECAST IS LOOKING PRETTY GOOD. RUC AND NEW NAM TOGETHER
SEEM TO HAVE A HANDLE ON THE SLOW DECREASE OF LOW CLOUDS FROM THE
SW. FOR A WHILE EARLIER I WAS THINKING OF A LITTLE FASTER CLEARING
BEHIND THE FLURRIES MOVING OUT ON RADAR...BUT THE LOW DECK IS
PROVING TOUGH TO BUDGE VERY FAST. ALSO AM LEAVING FLURRIES IN
DESPITE CURRENT VIRTUAL DISAPPEARANCE FROM RADAR...LOW CLOUD DECK
CAN EASILY PRODUCE A FEW AND THERE ARE IN FACT SOME NOW IN SOUTHWEST
MN. TEMPERATURES WILL NOT COOL VERY FAST AND HAVE UPPED LOW
TEMPERATURES A LITTLE...THEN OF COURSE LOOK FOR NOT MUCH WARMING
WEDNESDAY AS THE LITTLE REINFORCING SHOT OF COLD AIR SPREADS IN.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
AS EXPECTED...THERE IS STILL SOME MVFR CEILINGS LINGERING IN THE
EXTREME EASTERN SECTION OF EAST CENTRAL SD AND THROUGH SOUTHWEST MN.
BOTH THE LATEST NAM12 AND RUC13 MODELS ARE IN GOOD AGREEMENT IN
SLOWLY MOVING THE MVFR STRATUS EASTWARD ACROSS SOUTHWEST MN THROUGH
09Z TONIGHT. BUT THEN THE STRATUS MAY HANG UP NEAR THE MARSHALL AND
WINDOM MINNESOTA AREAS AS WINDS JUST OFF THE SURFACE SHIFT NORTHWEST
ALONG A COLD FRONT. THEREFORE MVFR CONDITIONS COULD LINGER IN OUR
EXTREME NORTHEAST ZONES WELL INTO WEDNESDAY MORNING. OTHERWISE
CONDITIONS SHOULD BE VFR FOR THE REST OF THE SIOUX FALLS FORECAST
AREA THROUGH WEDNESDAY EVENING. THERE IS A HIGHER DECK OF STRATUS
NEAR 4000 TO 5000 FT AGL TO THE WEST OF THE MVFR CEILINGS EXTENDING
FROM NEAR HURON SD...TO MOST OF NORTHWEST IA. HOWEVER VARIOUS MODELS
ALSO PROJECT THIS HIGHER BASED STRATUS TO EDGE EASTWARD THROUGH THE
REST OF THE NIGHT ALONG A WNW WIND COMPONENT IN THAT LAYER. SO THAT
SEEMS LOGICAL. AS BRIEFLY MENTIONED ABOVE...THERE WILL BE A COLD
FRONTAL PASSAGE ACROSS THE FORECAST AREA LATE TONIGHT AND VERY EARLY
WEDNESDAY. THEREFORE SURFACE WINDS WILL BE NORTH TO NORTHWEST ON
WEDNESDAY AND A BIT BREEZY. HOWEVER MOST GUSTS SHOULD STAY BELOW 25
KNOTS. /MJF
&&
.PREV DISCUSSION.../ISSUED AT 412 PM CST/
MODEST MID LEVEL FRONTOGENESIS IS EXPECTED TO CONTINUE TO SHIFT EAST
THROUGH THE FORECAST AREA THROUGH THIS EVENING AND INTO THE EARLY
MORNING HOURS. WHILE THE SNOW GROWTH ZONE DOES APPEAR TO BE QUITE
DENDRITIC...THINK THAT THERE WILL BE SOME DIFFICULTY GETTING MUCH
MORE THAN OCCASIONAL FLURRIES OUT OF THIS ACTIVITY GIVEN THE REAL
LACK OF MOISTURE...PARTICULARLY IN THE LOW LEVELS. NO SIGNIFICANT
ACCUMULATION IS EXPECTED AND WILL AT BEST BE A LIGHT DUSTING. LOW
TEMPERATURES WILL BE MILDER THAN IN RECENT DAYS DESPITE SOME
RELATIVELY LIGHT WINDS. MOSTLY CLOUDY SKIES AND SOME MINOR WARM AIR
ADVECTION SHOULD ALLOW LOWS TO ONLY FALL A FEW DEGREES FROM CURRENT
READINGS. HOURLIES WILL LIKELY BE TROUBLESOME...PARTICULARLY WITH A
VERY MINOR COLD FRONT ARRIVING LATE TONIGHT. SINGLE DIGITS ABOVE
ZERO AND LOWER TEENS ARE EXPECTED FOR LOWS.
EXPECT COLD AIR ADVECTION TO BEGIN ARRIVING BEHIND THE FRONT ON
WEDNESDAY...WITH NORTH NORTHWEST WINDS INCREASING TO AROUND 10 TO 15
MPH. TEMPERATURES WILL LIKELY CAP AROUND THE 10 TO 20 DEGREE RANGE
FOR HIGHS. AREAS IN THE NORTH IN PARTICULAR WILL SEE VERY LITTLE
WARMING AND MAY EVEN FIND TEMPERATURES FALLING A FEW DEGREES FROM
LATE MORNING READINGS. /
COLD LOW LEVEL AIR CONTINUES TO FILTER IN FROM THE NORTH ON
WEDNESDAY NIGHT. NOT A GREAT RADIATIONAL COOLING NIGHT THOUGH...WITH
A BREEZE STAYING UP AND MOSTLY CLOUDY SKIES. THUS THE MAV GUIDANCE
SEEMS WAY TOO COLD FOR LOWS. INSTEAD FAVOR A SOLUTION CLOSER TO THE
MET/NAM/ECMWF...GIVING NEGATIVE SINGLE DIGITS IN SOUTHWEST MINNESOTA
TO THE SINGLE DIGITS ABOVE ZERO IN THE SOUTH. SOUTHERLY FLOW
INCREASES ON THURSDAY BRINGING IN WARMER TEMPERATURES. UNFORTUNATELY
WITH SUCH A STRONG MORNING INVERSION...MUCH OF THIS WARMING WILL NOT
BE REALIZED. LOWERED HIGH TEMPERATURES SEVERAL DEGREES ACROSS THE
AREA...WITH TEENS ACROSS OUR EAST AND 20S IN THE SOUTHWEST. WILL BE
BREEZY AS WELL WITH A NICE LOW LEVEL JET DEVELOPING AHEAD OF AN
APPROACHING COLD FRONT. SOUTHERLY WIND GUSTS UP TO 30 MPH SEEM
LIKELY.
COLD FRONT APPROACHES FROM THE WEST THURSDAY...WITH AN ARCTIC FRONT
DROPPING SOUTH LATER THURSDAY NIGHT INTO FRIDAY MORNING. MODELS HAVE
TRENDED SLOWER WITH BOTH THESE FRONTAL PASSAGES...AND ARE IN PRETTY
GOOD AGREEMENT. THIS WILL LIKELY HAVE SIGNIFICANT IMPACTS ON
TEMPERATURES BOTH THURSDAY NIGHT AND FRIDAY. THE FRONT THURSDAY
EVENING AND NIGHT WILL MAINLY JUST BE A MIXING FRONT...WITH NOT MUCH
COLD AIR BEHIND IT. AND WITH THE ARCTIC FRONT DELAYED...RAISED LOWS
SIGNIFICANTLY THURSDAY NIGHT. GENERALLY EXPECTING TEENS AND 20S WITH
THE WARMEST CONDITIONS ACROSS SOUTH CENTRAL SOUTH DAKOTA. NORTHWEST
IOWA WILL HAVE THE BEST CHANCE TO RADIATE SOME IN THE EVENING BEFORE
ETHE MIXING FRONT...AND THUS SHOULD HAVE THE COLDEST LOWS. HIGHS
FRIDAY WILL LIKELY BE IN THE MORNING IN THE NORTH...WITH THE ARCTIC
FRONT PUSHING THROUGH DURING THE DAY. WITH THE SLOWER
TIMING...RAISED HIGHS SIGNIFICANTLY ON FRIDAY. HOWEVER AGAIN...MOST
AREAS WILL SEE FALLING TEMPERATURES BY LATER IN THE DAY. CURRENTLY
GOING WITH LOW TEENS NORTH TO THE LOW AND MID 20S SOUTH...HOWEVER IF
THE FRONT CONTINUES TO SLOW...COULD EVEN BE A BIT WARMER. WILL BE
WINDY OUT OF THE NORTHWEST LATER THURSDAY NIGHT INTO FRIDAY WITH
NEAR ADVISORY LEVEL POSSIBLE GIVEN 30 TO 40 KTS AT 925 MB. NOT
EXPECTING MUCH SNOW FROM EITHER OF THESE FRONTAL PASSAGES. DECENT
LARGE SCALE LIFT PASSES OVERHEAD THURSDAY EVENING...BUT THE DRY LOW
LEVELS SHOULD PREVENT ANYTHING FROM REACHING THE GROUND. THE UPPER
LOW THURSDAY NIGHT INTO FRIDAY EVENING HAS TRENDED FURTHER
NORTHEAST...WITH MOST MODEL SOLUTIONS LEAVING OUR CWA DRY. WILL KEEP
A CHANCE ACROSS SOUTHWEST MINNESOTA GOING...AS THINKING WE COULD SEE
AT LEAST SOME FLURRIES THERE.
A BIT OF AN UNCERTAIN LONG RANGE FORECAST...WITH MODEL UNCERTAINTY
AND RUN TO RUN CONSISTENCY ON THE LOW END. THERE IS AGREEMENT THAT
WE SEE A WEST COAST TROUGH MOVE IN WITH A POTENTIALLY MORE ACTIVE
PERIOD FOR US. FIRST UPPER LOW MOVES INTO SOUTHERN CALIFORNIA ON
FRIDAY NIGHT...AFTER WHICH MODEL SOLUTIONS DIVERGE. DOES LOOK LIKE
WE HAVE A SHOT OF SOME LIGHT SNOW OVER THE WEEKEND AS THIS LOW AND
ASSOCIATED TROUGH AXIS PUSHES EAST ACROSS THE PLAINS. UNFORTUNATELY
TIMING AND PLACEMENT CONFIDENCE REMAINS LOW. THUS LEFT ALLBLEND POPS
IN FOR THE MOST PART...WHICH SEEM TO MORE CLOSELY FOLLOW THE GFS
SOLUTION. BUT AGAIN NOT MUCH CONFIDENCE IN THIS...AND REALITY IS ANY
PART OF THE CWA COULD SEE SOME LIGHT SNOW OVER THE WEEKEND...BUT
DOES NOT LOOK LIKE ANY SIGNIFICANT STORM AT THIS POINT...WITH THE
WAVE ON THE WEAK SIDE. TEMPERATURES OVER THE WEEKEND ALSO CLOSE TO
ALLBLEND...20S SATURDAY AND 30S SUNDAY.
THE BIGGER LONGWAVE TROUGH BEGINS TO WORK EAST INTO EARLY NEXT WEEK.
COULD SEE SOME LIGHT SNOW...OR MAYBE RAIN AS THIS COMES ACROSS
MONDAY INTO TUESDAY. THIS TIME PERIOD HAS MORE POTENTIAL FOR
US...HOWEVER 12Z RUNS DO NOT GIVE ANY SIGNIFICANT SYSTEM. THE ECMWF
KEEPS THE TROUGH POSITIVELY TILTED LIMITING PRECIP...AND THE GFS
KEEPS THE LOW TO OUR SOUTH. BUT THIS TIME PERIOD WILL HAVE TO
CONTINUE TO BE MONITORED...AS WE AT LEAST HAVE A CHANCE OF A
STRONGER SYSTEM COMING OUT OF THIS PATTERN. ABOVE NORMAL
TEMPERATURES SHOULD CONTINUE THROUGH TUESDAY THOUGH...WITH HIGHS IN
THE 20S AND 30S AND LOWS IN THE TEENS AND 20S. /CHENARD
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS AMARILLO TX
1153 AM CST WED JAN 23 2013
.AVIATION...DISCUSSION FOR 18Z TAFS
VFR CONDITIONS WILL LIKELY DETERIORATE TO MVFR OR IFR CONDITIONS BY
LATE IN THE TAF PERIOD. A COLD FRONT WILL MOVE THROUGH THE AREA FROM
NE TO SW...WITH LOW CLOUDS SEEMINGLY A GOOD BET BEHIND THE FRONT. THE
HIGHEST CONFIDENCE FOR LOW CLOUDS IS AT KDHT AND KGUY...WHERE IFR
CIGS WERE INSERTED INTO THE TAFS. MUCH LOWER CONFIDENCE FOR LOW
CLOUDS EXISTS AT KAMA...WHERE LOW LEVEL MOISTURE COULD GET HUNG UP
AND NOT MAKE IT TO THE AIRPORT. AS SUCH...HAVE HINTED AT IFR
CONDITIONS WHILE INSERTING AN MVFR DECK. IT APPEARS THAT A NEAR
SURFACE DRY LAYER WILL PRECLUDE TOO MUCH IN THE WAY OF FG AT KAMA AND
KGUY...BUT FOG CHANCES LOOK BETTER AT KDHT. THE FOG FORECAST IS LOW
CONFIDENCE.
WINDS WILL GENERALLY BE LIGHT...SHIFTING TO THE NE IN THE SECOND
HALF OF THE TAF PERIOD.
SIMPSON
&&
.PREV DISCUSSION... /ISSUED 959 AM CST WED JAN 23 2013/
UPDATE...
HAVE MADE A QUICK UPDATE TO THE FORECAST TODAY TO INCREASE HIGHS BY
2-4 DEGREES IN MOST AREAS. WARMER MET GUIDANCE IS PREFERRED TO
MAV GUIDANCE AND THE LATEST RUC SUPPORTS THE WARMER READINGS. HIGHS
SHOULD PUSH INTO THE 70S FOR MANY AREAS...BUT DAILY RECORDS SHOULD
STAY SAFE. UPDATED GRIDS/ZONES ARE OUT.
SITE RECORD FOR TODAY FORECAST HIGH
AMARILLO 77 71
BORGER 77 71
DALHART 74 72
SIMPSON
PREV DISCUSSION... /ISSUED 529 AM CST WED JAN 23 2013/
AVIATION...
FOR THE 12Z TAFS...VFR CONDITIONS ARE EXPECTED THROUGH THE TAF
PERIOD. WINDS WILL GENERALLY BE LIGHT...OUT OF THE WEST OR SOUTHWEST
FOR THE FIRST HALF OF THE TAF PERIOD. AFTER 00Z...A BACKDOOR COLD
FRONT WILL MOVE INTO THE REGION FROM THE NORTHEAST TO
SOUTHWEST...SHIFTING WINDS TO NORTHEASTERLY. BUFKIT SOUNDINGS AND
TIME HEIGHT DISPLAYS OF BOTH THE NAM AND GFS INDICATE A VERY THIN
SATURATED LOW LAYER AFTER 06Z...BEHIND THE FRONT. AND WHILE THE WIND
DIRECTION IS FAVORABLE FOR FG OR LOW STRATUS DEVELOPMENT...STILL
BELIEVE THIS IS UNLIKELY JUST GIVEN HOW THIN THE DEPICTED LAYER
IS.
JOHNSON
PREV DISCUSSION... /ISSUED 355 AM CST WED JAN 23 2013/
DISCUSSION...
AN UPPER RIDGE BUILDS IN OVER THE CENTRAL AND SOUTHERN ROCKIES TODAY
AND THEN SLOWLY BUILDS EASTWARD TONIGHT ACROSS WEST TEXAS AND THE
PANHANDLES BEFORE BREAKING DOWN THURSDAY. A SURFACE LOW OVER EASTERN
AND SOUTHEASTERN COLORADO TODAY DROPS SOUTH AND EAST TONIGHT INTO THE
WESTERN PANHANDLES. THIS WILL USHER IN A BACKDOOR COLD FRONT INTO THE
FORECAST AREA TONIGHT AND EARLY THURSDAY. AND EASTERLY AND
NORTHEASTERLY UPSLOPE SURFACE FLOW IS EXPECTED BEHIND THE BACKDOOR
COLD FRONT TONIGHT BRINGING IN ABUNDANT LOW LEVEL MOISTURE INTO THE
PANHANDLES. AFTER ONE FINAL DAY OF ABOVE NORMAL CONDITIONS
TODAY...MOST OF THE FORECAST AREA WILL EXPERIENCE MUCH COOLER
CONDITIONS AND INCREASING CLOUD COVER AS SURFACE RIDGE BUILDS
SOUTHWEST INTO THE PANHANDLES ON THURSDAY. THE LONE EXCEPTION MAY BE
THE SOUTHWEST TEXAS PANHANDLE WHERE STILL SOME ABOVE NORMAL
CONDITIONS MAY OCCUR WITH AMPLE SUNSHINE AND WHERE THE FRONT MAY
STALL BY LATE THURSDAY. REINFORCING SURFACE HIGH BUILDS IN OVER
KANSAS AND OKLAHOMA BY FRIDAY ALLOWING THE COLD FRONT TO SURGE
SOUTHWARD LATE IN THE WEEK.
SOUTHERN STREAM SHORTWAVE TROUGH TRACKS ACROSS THE SOUTHWESTERN
STATES AND SOUTHERN ROCKIES SATURDAY AND SATURDAY NIGHT BRINGING
INCREASING CHANCES FOR PRECIPITATION TO THE PANHANDLES THIS WEEKEND.
WARM AIR ADVECTION PATTERN AHEAD OF THE APPROACHING UPPER SYSTEM WILL
ALLOW FOR ABOVE FREEZING TEMPS AND SHOULD KEEP THE PRECIPITATION IN
LIQUID FORM SATURDAY AND SATURDAY NIGHT. SURFACE LOW AND WARM FRONT
MOVE ACROSS THE FORECAST AREA SATURDAY NIGHT INTO EARLY SUNDAY
BRINGING AN END TO THE PRECIPITATION FROM WEST TO EAST BY SUNDAY
MORNING. DEEPENING SURFACE LOW OVER EASTERN WYOMING BY MONDAY WILL
RESULT IN TIGHTENING OF THE SURFACE PRESSURE GRADIENT EARLY NEXT WEEK
AND ALLOW FOR INCREASING DOWNSLOPING SOUTHWESTERLY WINDS INTO THE
BREEZY AND WINDY CRITERIA. AS THE SURFACE LOW TRACKS SOUTHWARD INTO
EASTERN COLORADO MONDAY NIGHT AND THEN EASTWARD ACROSS THE CENTRAL
PLAINS STATES EARLY TUESDAY...A COLD FRONT WILL MOVE THROUGH THE
PANHANDLES BY 18Z TUESDAY. MAY NEED AT LEAST A WIND ADVISORY BY NEXT
TUESDAY...HOWEVER CONFIDENCE TOO LOW TO MENTION AT THIS TIME. DRY
EARLY NEXT WEEK.
SCHNEIDER
FIRE WEATHER...
ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE NOT EXPECTED THROUGH
EARLY NEXT WEEK AS EITHER THE 20 FOOT WIND SPEEDS REMAIN AT OR BELOW
15 TO 20 MPH...OR THE MINIMUM AFTERNOON RELATIVE HUMIDITIES REMAIN AT
OR ABOVE 15 TO 20 PERCENT THROUGH THE FORECAST PERIOD.
SCHNEIDER
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
09/08
AREA FORECAST DISCUSSION...UPDATED
NWS AMARILLO TX
959 AM CST WED JAN 23 2013
.UPDATE...
HAVE MADE A QUICK UPDATE TO THE FORECAST TODAY TO INCREASE HIGHS BY
2-4 DEGREES IN MOST AREAS. WARMER MET GUIDANCE IS PREFERRED TO
MAV GUIDANCE AND THE LATEST RUC SUPPORTS THE WARMER READINGS. HIGHS
SHOULD PUSH INTO THE 70S FOR MANY AREAS...BUT DAILY RECORDS SHOULD
STAY SAFE. UPDATED GRIDS/ZONES ARE OUT.
SITE RECORD FOR TODAY FORECAST HIGH
AMARILLO 77 71
BORGER 77 71
DALHART 74 72
SIMPSON
&&
.PREV DISCUSSION... /ISSUED 529 AM CST WED JAN 23 2013/
AVIATION...
FOR THE 12Z TAFS...VFR CONDITIONS ARE EXPECTED THROUGH THE TAF
PERIOD. WINDS WILL GENERALLY BE LIGHT...OUT OF THE WEST OR SOUTHWEST
FOR THE FIRST HALF OF THE TAF PERIOD. AFTER 00Z...A BACKDOOR COLD
FRONT WILL MOVE INTO THE REGION FROM THE NORTHEAST TO
SOUTHWEST...SHIFTING WINDS TO NORTHEASTERLY. BUFKIT SOUNDINGS AND
TIME HEIGHT DISPLAYS OF BOTH THE NAM AND GFS INDICATE A VERY THIN
SATURATED LOW LAYER AFTER 06Z...BEHIND THE FRONT. AND WHILE THE WIND
DIRECTION IS FAVORABLE FOR FG OR LOW STRATUS DEVELOPMENT...STILL
BELIEVE THIS IS UNLIKELY JUST GIVEN HOW THIN THE DEPICTED LAYER
IS.
JOHNSON
PREV DISCUSSION... /ISSUED 355 AM CST WED JAN 23 2013/
DISCUSSION...
AN UPPER RIDGE BUILDS IN OVER THE CENTRAL AND SOUTHERN ROCKIES TODAY
AND THEN SLOWLY BUILDS EASTWARD TONIGHT ACROSS WEST TEXAS AND THE
PANHANDLES BEFORE BREAKING DOWN THURSDAY. A SURFACE LOW OVER EASTERN
AND SOUTHEASTERN COLORADO TODAY DROPS SOUTH AND EAST TONIGHT INTO THE
WESTERN PANHANDLES. THIS WILL USHER IN A BACKDOOR COLD FRONT INTO THE
FORECAST AREA TONIGHT AND EARLY THURSDAY. AND EASTERLY AND
NORTHEASTERLY UPSLOPE SURFACE FLOW IS EXPECTED BEHIND THE BACKDOOR
COLD FRONT TONIGHT BRINGING IN ABUNDANT LOW LEVEL MOISTURE INTO THE
PANHANDLES. AFTER ONE FINAL DAY OF ABOVE NORMAL CONDITIONS
TODAY...MOST OF THE FORECAST AREA WILL EXPERIENCE MUCH COOLER
CONDITIONS AND INCREASING CLOUD COVER AS SURFACE RIDGE BUILDS
SOUTHWEST INTO THE PANHANDLES ON THURSDAY. THE LONE EXCEPTION MAY BE
THE SOUTHWEST TEXAS PANHANDLE WHERE STILL SOME ABOVE NORMAL
CONDITIONS MAY OCCUR WITH AMPLE SUNSHINE AND WHERE THE FRONT MAY
STALL BY LATE THURSDAY. REINFORCING SURFACE HIGH BUILDS IN OVER
KANSAS AND OKLAHOMA BY FRIDAY ALLOWING THE COLD FRONT TO SURGE
SOUTHWARD LATE IN THE WEEK.
SOUTHERN STREAM SHORTWAVE TROUGH TRACKS ACROSS THE SOUTHWESTERN
STATES AND SOUTHERN ROCKIES SATURDAY AND SATURDAY NIGHT BRINGING
INCREASING CHANCES FOR PRECIPITATION TO THE PANHANDLES THIS WEEKEND.
WARM AIR ADVECTION PATTERN AHEAD OF THE APPROACHING UPPER SYSTEM WILL
ALLOW FOR ABOVE FREEZING TEMPS AND SHOULD KEEP THE PRECIPITATION IN
LIQUID FORM SATURDAY AND SATURDAY NIGHT. SURFACE LOW AND WARM FRONT
MOVE ACROSS THE FORECAST AREA SATURDAY NIGHT INTO EARLY SUNDAY
BRINGING AN END TO THE PRECIPITATION FROM WEST TO EAST BY SUNDAY
MORNING. DEEPENING SURFACE LOW OVER EASTERN WYOMING BY MONDAY WILL
RESULT IN TIGHTENING OF THE SURFACE PRESSURE GRADIENT EARLY NEXT WEEK
AND ALLOW FOR INCREASING DOWNSLOPING SOUTHWESTERLY WINDS INTO THE
BREEZY AND WINDY CRITERIA. AS THE SURFACE LOW TRACKS SOUTHWARD INTO
EASTERN COLORADO MONDAY NIGHT AND THEN EASTWARD ACROSS THE CENTRAL
PLAINS STATES EARLY TUESDAY...A COLD FRONT WILL MOVE THROUGH THE
PANHANDLES BY 18Z TUESDAY. MAY NEED AT LEAST A WIND ADVISORY BY NEXT
TUESDAY...HOWEVER CONFIDENCE TOO LOW TO MENTION AT THIS TIME. DRY
EARLY NEXT WEEK.
SCHNEIDER
FIRE WEATHER...
ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE NOT EXPECTED THROUGH
EARLY NEXT WEEK AS EITHER THE 20 FOOT WIND SPEEDS REMAIN AT OR BELOW
15 TO 20 MPH...OR THE MINIMUM AFTERNOON RELATIVE HUMIDITIES REMAIN AT
OR ABOVE 15 TO 20 PERCENT THROUGH THE FORECAST PERIOD.
SCHNEIDER
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
09/08
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
922 PM CST THU JAN 24 2013
.UPDATE...
AREA 00Z RAOBS SHOWING THE VERY DRY LAYER...DEW POINT DEPRESSIONS
ON THE ORDER OF 30C IN THE 850-800MB LAYER...THAT HAVE BEEN
PREVENTING MUCH IN THE WAY OF GROUND TRUTH BELOW THE 15 TO 20 DBZ
RETURNS WITH THE INITIAL WAA ALL THE WAY BACK TO CENTRAL MN. SNOW
REPORTS HAVE BEEN LIMITED TO NRN MN AND NW WI. LATEST 01Z RAP AND
NEW 00Z NAM SHOW THE DRY LAYER AROUND 850 MB WILL BE TOUGH TO
SATURATE OVER THE CWA UNTIL AFTER 09Z...WITH REDUCED QPF AMOUNTS.
23Z HRRR DOES NOT BRING ANY QPF INTO THE CWA FOR THIS EVENT.
RAP AND NAM SOUNDINGS DO EVENTUALLY SATURATE. REDUCED QPF AND THUS
SNOW AMOUNTS ACROSS THE CWA...BUT STILL WORRIED ABOUT HIGH SNOW TO
LIQUID RATIOS WITH THE DEPTH OF OF THE SATURATED DENDRITIC GROWTH
ZONE...WITH SPC PROBABILITY OF 200 MB OR MORE AROUND 90 PCT ACROSS
THE FAR NORTH AND 50 PCT DOWN TO THE IL BORDER IN THE ERN CWA.
THE DEEP DGZ IS BEING SHOWN ON RAP SOUNDINGS IN THE EAST WITH
DECENT OMEGA...SO ONLY REDUCED THE AMOUNTS BY 1/2 INCH TO 1 INCH
FOR NOW.
&&
.AVIATION/06Z TAFS/...COMING SOON.
.MARINE...COMING SOON.
&&
.PREV DISCUSSION... /ISSUED 410 PM CST THU JAN 24 2013/
SHORT TERM...
TONIGHT AND FRIDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
WILL SEE SOME LAKE EFFECT JUST BRUSH THE LAKE SHORE INTO THE
EVENING. NOT REALLY EXPECTING MUCH MORE THAN FLURRIES. BIGGER ISSUE
WILL BE WIDESPREAD SNOWFALL TONIGHT INTO FRIDAY. HIGH CONFIDENCE IN
ACCUMULATING SNOW ACROSS THE FORECAST AREA. MAIN PROBLEMS ARE TIMING
OF THE SNOW AND AMOUNTS. THE NAM AND GFS CONTINUE TO CHEW ON A LOT
OF DRY AIR THIS EVENING INTO EARLY TONIGHT...WHILE THE ECMWF AND
CANADIAN SATURATE A LOT FASTER. LEANED TOWARD THE SLOWER SOLUTIONS
BASED ON SHORT TERM MESO MODELS LOOKING SIMILAR TO THE NAM.
LIQUID TO SNOW RATIOS ARE THE OTHER ISSUE. SOUNDINGS ARE SHOWING A
VERY DEEP DENDRITE GROWTH LAYER...AS DEEP AS 350 MB IN THE NORTH.
WITH 1000-500 MB THICKNESS VALUES IN THE 520S AND AND TEMPERATURES
IN THE TEENS...EXPECTING VERY HIGH SNOW RATIOS. TOOK THEM AS HIGH 25
TO 1 IN THE NORTH...BUT WOULD NOT BE SURPRISED IF THEY GET EVEN
HIGHER. ENDED UP WITH SIMILAR STORM TOTAL SNOW AMOUNTS AS PREVIOUS
FORECAST...RANGING FROM 1 TO 2 INCHES IN THE SOUTHWEST FORECAST AREA
TO 3 TO 4 IN THE NORTHEAST. THOUGHT ABOUT A WINTER WEATHER ADVISORY
IN THE NORTHEAST...BUT WINDS STAY UNDER CONTROL WHILE THE SNOW IS
FALLING...AND AMOUNTS ARE GENERALLY BORDERLINE FOR AN ADVISORY. MAY
CAUSE A FEW ISSUES FOR THE MORNING COMMUTE...ESPECIALLY IN THE EAST
WHERE THE SNOW WILL HANG ON LATER INTO THE MORNING.
WIDESPREAD SNOW WILL WIND DOWN TOMORROW MORNING...WITH SNOW SHOWERS
POSSIBLY LINGERING INTO THE AFTERNOON...ESPECIALLY IN THE NORTHEAST.
LOOKS LIKE HIGHS ACTUALLY BACK NEAR NORMAL TOMORROW.
FRIDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE MEDIUM
BRISK NWLY WINDS AND COLD ADVECTION IN THE WAKE OF LOW PRESSURE
MOVING EAST ACROSS THE GREAT LAKES WILL RETURN AN ARCTIC AIRMASS
TO THE REGION FOR FRI NT. STEEP LOW LEVEL LAPSE RATES IN THE
EARLY EVENING COULD MAINTAIN FLURRIES OR LIGHT SNOW SHOWERS IN ERN
WI BEFORE CLEARING ARRIVES LATER IN THE EVENING. A 1030 MB POLAR
HIGH WILL PROGRESS EWD ACROSS SRN WI SAT INTO EARLY SAT EVENING
WITH LARGE SCALE RIDGING OVER THE PLAINS IN RESP0NSE TO AN
UPSTREAM UPPER TROUGH IN THE PACIFIC NW AND A SHORTWAVE TROUGH
MOVING INTO THE DESERT SW.
THE SHORTWAVE TROUGH OVER THE DESERT SW WILL THEN LIFT NEWD AND
EITHER TRACK INTO SRN WI OR REMAIN JUST TO THE SOUTH. THE
ASSOCIATED PRESSURE TROUGH/WARM FRONT WILL PRODUCE A GOOD BAND OF
PCPN BUT MODELS DIFFER ON PLACEMENT OF IT...SOME KEEPING THE MAIN
AREA TO THE SOUTH. KEPT POPS IN THE 40-60 PERCENT RANGE FOR NOW.
EITHER WAY...PCPN TYPE LOOKS MIXY. THERE COULD BE A BRIEF PERIOD OF
TOTAL COLUMN SATURATION LEADING TO SNOW BUT DRIER AIR ALOFT AND A
WARM LAYER COULD THEN RESULT IN FREEZING RAIN...FREEZING
DRIZZLE...AND SLEET. PUT IN LIGHT ICE AND SNOW ACCUMULATION INTO
SUNDAY FCST. THIS WOULD CONTINUE SUN NT AND POSSIBLY LINGER INTO
MONDAY ALTHOUGH TEMPS MAY WARM ABOVE FREEZING...MEANING RAIN FOR
PCPN TYPE.
TEMPS EXPECTED TO GRADUALLY WARM THROUGH THIS PERIOD WITH HIGHS
ABOVE FREEZING FOR MONDAY.
LONG TERM...
TUESDAY THROUGH THURSDAY...FORECAST CONFIDENCE LOW TO MEDIUM
MODELS DIFFER ON STRENGTH AND PLACEMENT OF CYCLOGENESIS FROM THE
PLAINS NEWD INTO ONTARIO CANADA FOR MON NT THROUGH WED...THUS THE
LOWER CONFIDENCE. GIVEN THE TRACK IS TO THE WEST AND NORTH STILL
WENT MILD WITH CHANCES OF RAIN THROUGH TUE. A STRONG COLD FRONT
WILL THEN SWEEP THROUGH THE STATE TUE NT WITH RAIN CHANGING TO
SNOW. BRISK NWLY WINDS AND COLD ADVECTION WILL PREVAIL INTO WED
WITH A POLAR AIRMASS RETURNING. HIGH PRESSURE TO THEN SETTLE OVER
THE REGION ON THU WITH BELOW NORMAL TEMPS EXPECTED.
AVIATION/00Z TAFS/...
MID AND HIGH LEVEL CLOUDS WILL KEEP SKIES MAINLY OVERCAST THROUGH
THE REMAINDER OF THE DAY. WILL CONTINUE TO SEE CIGS NEAR MVFR LATE
THIS AFTERNOON IN THE SOUTHEAST AS LAKE EFFECT SNOW SHOWERS BRUSH
THE LAKE SHORE. STILL NOT EXPECTING MUCH IN THE WAY OF
ACCUMULATION...IF ANYTHING AT ALL. OTHERWISE...DRY WEATHER AND VFR
CONDITIONS WILL PREVAIL THROUGH THE EVENING HOURS.
WILL SEE DETERIORATING CONDITIONS AFTER MIDNIGHT...AS WIDESPREAD
SNOWFALL MOVES INTO THE AREA. MVFR CONDITIONS ARE LIKELY...WITH
POSSIBLY LOWER VSBYS IN ANY AREAS OF MODERATE SNOWFALL. THE
WIDESPREAD SNOWFALL WILL WIND DOWN FRIDAY MORNING...THOUGH COULD
SEE A FEW SNOW SHOWERS LINGER INTO THE AFTERNOON. WILL LIKELY SEE
MVFR CIGS LINGER THOUGH MUCH OF THE DAY TOMORROW.
MARINE...
WILL LET CURRENT SMALL CRAFT ADVISORY EXPIRE AT SCHEDULED 22Z TIME.
LATEST WEBCAMS AND WAVE MODEL SHOW WAVES GENERALLY BELOW 4 FEET NOW.
SOUTH WINDS WILL PICK UP TONIGHT...WITH WAVES LIKELY EXCEEDING 4
FEET NORTH OF PORT WASHINGTON. WILL THUS ISSUE ANOTHER SMALL CRAFT
ADVISORY FOR LATE TONIGHT INTO FRIDAY AFTERNOON FOR THE NORTHERN
MARINE ZONE.
WINDS WILL BE CLOSE TO SMALL CRAFT ADVISORY ACROSS THE NEARSHORE
WATERS LATER FRIDAY INTO FRIDAY NIGHT. SEEMS TOO BORDERLINE FOR AN
ADVISORY AT THIS TIME THOUGH.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 3 AM TO 4 PM CST FRIDAY FOR LMZ643.
&&
$$
UPDATE...REM
TONIGHT/FRIDAY AND AVIATION/MARINE...DDV
FRIDAY NIGHT THROUGH THURSDAY...GEHRING
AREA FORECAST DISCUSSION...UPDATED
NWS GREEN BAY WI
834 PM CST THU JAN 24 2013
.UPDATE...DRY AIR AT LOW-LEVELS REALLY PLAYING HAVOC WITH THIS
FCST. 00Z RAOBS FM GRB/MPX STILL VERY DRY AT LOW-LEVELS. DVN AND
ILX DRY TOO...INDICATING SLY FLOW WL CONT TO REINFORCE THE DRY
AIR AS PCPN FALLING FM MID-DECK ABV TRIES TO SATURATE IT. DON/T
HAVE A HIGH DEGREE OF CONFIDENCE IN HOW THIS WILL ALL ULTIMATELY
PLAY OUT...BUT CURRENT FCST IS GOING TO NEED SOME ADJUSTMENTS.
FIRST...GOING TO DELAY THE START OF THE ADVISORY FOR MANY AREAS.
WL ALLOW THE FAR NW TO START AT 03Z AS PLANNED...BUT HOLD OFF ON
THE REST OF THE N UNTIL AT LEAST 06Z. INITIAL SURGE OF ISENT LIFT
PCPN MAY NOT COME TOGETHER UNTIL IT IS NE OF THE GRB/FOX CITIES
AREA...SO WL DELAY ADVISORY FOR THESE AREAS UNTIL 09Z.
ON THE FLIP SIDE...LAKE-EFFECT SNOW BAND CONTD TO BACK WWD TOWARD
THE SHORE. BAND HAD SEVERAL EMBEDDED MESO-VORTICIES...AND RADAR
RETURNS SUGGESTED SOME DECENT SNOWFALL RATES. PLUS...BAND COULD
INTENSIFY WHEN IT STARTS TO GET SEEEDED FM ABV. SO...SINCE WE ARE
GOING TO HAVE AN ADVISORY FOR THE LAKESHORE ANYWAY...WL MOVE THE
START TIME OF THAT UP TO 03Z TO ACCOUNT FOR THE LAKE-EFFECT.
EXPERIENCE HAS SHOWN THAT WHENEVER YOU NEED TO DELAY THE ONSET OF
AN EVENT SUCH AS THIS...YOU ALMOST ALWAYS NEED TO CHOP SNOW TOTALS
AS WELL. WITH ISENT LIFT PCPN NOW LOOKING LESS SIG...MUCH OF THE
ACCUMULATION WL NEED TO COME FM UPR SHRTWV. VORT PROGGED TO TRACK
SE ACRS THE FCST AREA...RIGHT TOWARD GRB TOMORROW AFTN. THAT
SUGGESTS MAX SNOWS OVER NRN/NE WI. WL LEAVE TOTALS SIMILAR TO PREV
FCST THERE...BUT CUT BACK FARTHER TO THE S AND W.
UPDATED PRODUCT SUITE OUT ASAP.
SKOWRONSKI
&&
.PREV DISCUSSION...ISSUED AT 615 PM CST THU JAN 24 2013...
UPDATE...DONT LIKE AT ALL THE WAY THE SITN IS EVOLVING THIS
EVENING. LOW-LEVELS REMAIN VERY DRY...AND SLY FLOW AHEAD OF THE
INCOMING SYSTEM WL CONT TO REINFORCE THE DRY AIR FM THE S. THAT
COULD PLAY HAVOC WITH THE ONSET OF PCPN...THE TIMING OF THE
ADVISORY...AND SNOW AMNTS. RAP PAINTING A MUCH DIFFERENT PICTURE
THAN THE REST OF THE GUID. IT HAS BAND OF SNOW IN ISENT LIFT ZONE
TRYING TO CONSOLIDATE AS IT WORKS ACRS THE FCST AREA THIS EVENING.
BUT THEN THAT BAND PUSHES OFF TO THE E AFTER MIDNIGHT...WITH AT
LEAST A SEVERAL HR LULL IN THE PCPN BEFORE LOW-LEVELS SATURATE
AGAIN AND PCPN WITH THE UPR SHRTWV ARRIVES. IT/S RATHER HARD TO
ARGUE WITH THAT IDEA GIVEN THE CURRENT RADAR TRENDS...AND THE VERY
LIMITED NUMBER OF OB SITES REPORTING SNOW IN MN/NW WI EARLY THIS
EVENING. NOT READY TO MAKE ANY SIG CHGS TO THE FCST YET... THOUGH
THAT MAY BECOME NECESSARY IF CURRENT RADAR/OB TRENDS HOLD.
ONE AREA THAT COULD SEE SNOW A LITTLE EARLIER THAN EXPECTED IS THE
LAKESHORE RGN OF MTW COUNTY. MESOSCALE CIRCULATION WORKING NWD
OVER WRN LAKE MICHIGAN COULD GET SOME SHSN AND FLURRIES INTO
LAKESHORE AREAS DURING THE EVENING.
GOING TO UPDATE THE FCST FOR THE LAKE-EFFECT NOW...BUT HOLD OFF
MAKING ANY MORE SUBSTANTIAL CHGS FOR NOW.
SKOWRONSKI
DISCUSSION ISSUED AT 541 PM CST THU JAN 24 2013...
SHORT TERM...TONIGHT AND FRIDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH
PRESSURE CENTERED ACROSS THE STATE EARLY THIS AFTERNOON. MID AND
HIGH CLOUDS ARE ALREADY ON THE INCREASE...HOWEVER...AHEAD OF THE
NEXT SHORTWAVE TROUGH MOVING ESE OVER SOUTHERN SASKATCHEWAN. RADARS
ARE PUSHING AN AREA OF LIGHT TO MODERATE SNOW OVER FAR NORTHERN
NORTH DAKOTA AND SOUTHERN MANITOBA AND IS STARTING TO ENTER NORTHERN
MINNESOTA. AS THE SHORTWAVE TRACKS TOWARDS THE REGION TONIGHT AND
OVER THE REGION ON FRIDAY...SNOWFALL AMOUNTS AND HEADLINES ARE THE MAIN
FORECAST CONCERNS.
TONIGHT...SHORTWAVE TROUGH OVER THE SOUTHERN CANADIAN PRAIRIE WILL
DIVE SOUTHEAST TONIGHT ON ITS WAY TO THE ARROWHEAD OF MINNESOTA BY
12Z FRIDAY. AHEAD OF THE SHORTWAVE...FORCING IN THE FORM OF DPVA
AND ISENTROPIC ASCENT ON THE 280-285K SURFACES WILL SPREAD SOUTHEAST
WHICH WILL LEAD TO A WARM ADVECTION BAND ENTERING NW WISCONSIN BY
00-03Z AND NORTH-CENTRAL AND NORTHEAST WISCONSIN IN THE 03-06Z TIME
PERIOD. PLENTY OF UNCERTAINTY WITH THE DETAILS...INCLUDING WHERE
AND WHEN THE BAND ENTERS THE FORECAST AREA...AND ALSO SNOWFALL
RATIOS. THE LATEST SHORTER RANGE GUIDANCE INDICATES THAT A WARM
ADVECTION SNOW BAND WILL DIVE SE INTO RHI-GRB LINE BETWEEN 03-06Z
BEFORE WIDESPREAD SNOW ENTERS THE AREA AFTER MIDNIGHT. FGEN AND
INSTABILITY ALOFT ARE NOT PARTICULARLY IMPRESSIVE...BUT MICROPHYSICS
ARE A DIFFERENT STORY. BUFKIT SOUNDINGS FOR THE BOTH THE NAM/GFS
INDICATE AN ISOTHERMAL LAYER FROM THE SURFACE TO ABOUT
575MB...FIRMLY IN THE DENDRITIC GROWTH ZONE. ASCENT WONT OCCUPY
THIS ENTIRE LAYER...BUT SHOULD COINCIDE FOR ABOUT 200MB FROM LATE
THIS EVENING THROUGH EARLY FRIDAY MORNING. AS A RESULT...DESPITE
MEDIOCRE FORCING AND INSTABILITY...SHOULDNT TAKE MUCH QPF IN ORDER
TO GET A SUBSTANTIAL AMOUNT OF SNOW. ESTIMATING SNOWFALL RATIOS OF
20-30:1 WILL YIELD WIDESPREAD 2-4 INCH AMOUNTS BY MORNING FROM
NORTH-CENTRAL WISCONSIN TO THE SOUTHERN FOX VALLEY. WILL ADD
WAUPACA AND THE REST OF THE FOX VALLEY/LAKESHORE TO THE WINTER
WEATHER ADVISORY SINCE THE SNOW WILL BE FLYING DURING THE MORNING
RUSH HOURS WHERE 2-3 INCHES WILL PROBABLY ALREADY HAVE FALLEN. WILL
ALSO BUMP UP THE START TIME OVER N-C WISCONSIN TO START IT AT 03Z.
FRIDAY...THE SHORTWAVE WILL PASS ACROSS THE AREA DURING THE
DAY...AND IT WILL PUSH A SURFACE LOW ACROSS NORTHERN WISCONSIN
DURING THE AFTERNOON. FORCING WILL BE SHIFTING TO THE SOUTHEAST
FRIDAY MORNING...WHICH MAY LEAD TO SOME DRY SLOTTING OVER CENTRAL
AND EAST-CENTRAL WISCONSIN. BUT DEEPER COMMA HEAD MOISTURE DOES PASS
OVER NORTH-CENTRAL AND NORTHEAST WISCONSIN DURING THE DAY...WHERE
HIGHER ACCUMS SHOULD RESIDE. WILL STILL HAVE THE VERY GOOD SNOW
RATIOS FOR MUCH OF THE DAY...AND CAN SEE ADDITIONAL 1-2 INCHES OVER
NORTHEAST HALF OF THE FORECAST AREA...AND LESS THAN AN INCH OVER THE
SOUTHWEST. WINDS MAY START TO GET GUSTY LATE IN THE
AFTERNOON...WHICH MAY LEAD TO MINOR BLOWING AND DRIFTING SNOW.
HIGHS IN THE MID TEENS TO MID 20S.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
CLIPPER SYSTEM WILL CONTINUE TO MOVE AWAY FROM THE AREA FRIDAY
NIGHT. COULD BE A BRIEF PERIOD OF GUSTY WINDS AND BLOWING AND
DRIFTING OF THE SNOW AS SYSTEM MOVES AWAY AND COLDER AIR FILTERS
INTO THE REGION. WILL MENTION IT IN THE HAZARDOUS WEATHER OUTLOOK...
BUT WILL NOT HAVE IT IN THE GRIDS DUE TO THE BRIEF NATURE OF THE
EVENT. OTHERWISE...LAKE EFFECT SNOW SHOWERS WILL CONTINUE THROUGH
MOST OF THE NIGHT ACROSS THE FAR NORTH. HAVE INCREASED POPS INTO
THE CATEGORICAL RANGE FOR VILAS COUNTY AND INCREASED POPS OVER
THE REMAINDER OF THE NORTH AS WELL. DID ADD A CHANCE OF FLURRIES
THROUGH MOST OF THE NIGHT ACROSS THE SOUTH UNTIL CLEARING ARRIVES.
DID SLOW THE ARRIVAL OF THE CLEARING BY SEVERAL HOURS...MAINLY DUE
TO COLD NORTHERLY FLOW OFF THE WARMER WATERS OF LAKE SUPERIOR.
MODELS DO SHOW DRYING OF THE 850MB MOISTURE TOWARDS 12Z ACROSS
CENTRAL WISCONSIN. ON SATURDAY...DID LEAVE A FEW LINGERING FLURRIES
FOR A FEW HOURS SATURDAY MORNING ACROSS THE FAR NORTH/NORTHEAST.
WITH SUCH A COLD AIR MASS IN PLACE...ANY CUMULUS CLOUD COULD PRODUCE
A FEW FLURRIES BEFORE DISSIPATING.
NEW QUESTIONS ARISE FOR THE SATURDAY NIGHT PERIOD. LATEST WRF/CANADIAN
NOW PRODUCE A FEW INCHES OF LIGHT SNOW ACROSS CENTRAL AND NORTHERN
WISCONSIN...WHILE THE GFS/ECMWF DO NOT SHOW THIS FEATURE. WILL HAVE
A SLIGHT CHANCE OF LIGHT SNOW ACROSS THE NORTH FOR NOW.
CONFIDENCE REMAINS LOW THROUGHOUT THE REST OF THE FORECAST PERIOD
WITH HANDLING OF SYSTEM SUNDAY NIGHT AND SUNDAY NIGHT...AND AGAIN
TUESDAY. LATEST CANADIAN/ECMWF MODELS HAVE SHIFTED SYSTEM SUNDAY/
SUNDAY NIGHT FURTHER SOUTH AND WOULD JUST CLIP OUR FAR SOUTH. SINCE
MODELS HAVE BEEN JUMPING AROUND SIGNIFICANT ON LOCATION OF THIS SYSTEM...
WILL CONTINUE WITH PERSISTENCE FOR NOW UNTIL THERE IS A CLEAR
TREND. PRECIPITATION TYPE ISSUES STILL CONTINUE WITH THIS SYSTEM
WILL PRECIPITATION COULD END UP AS LIGHT SNOW...FREEZING RAIN OR
SLEET.
THE SYSTEM FOR TUESDAY CONTINUE TO BE PROBLEMATIC AS THE ECMWF
CONTINUES TO GO BACK AND FORTH WITH SURFACE LOW TRACKING WEST OF
GREEN BAY. THE GFS CONTINUED THIS TREND ON THE MORNING RUN...BUT 12Z
ECMWF HAS NO SUCH FEATURE ON THIS RUN. WILL CONTINUE WITH PERSISTENCE
WITH THIS PERIOD AS WELL UNTIL MODELS CONVERGE ON A CLEAR SOLUTION.
AT OR ABOVE NORMAL TEMPERATURES ARE EXPECTED MONDAY AND TUESDAY...THEN
BELOW NORMAL TEMPERATURES ARE EXPECTED LATE NEXT WEEK AS ANOTHER
SURGE OF ARCTIC AIR WILL SWEEP INTO THE NORTHERN UNITED STATES.
&&
.AVIATION...FOR 00Z TAF ISSUANCE. VFR CONDITIONS EARLY THIS
EVENING WL WORSEN TO LOWER END MVFR OR IFR BY LATE TNGT AS SNOW
MVS INTO THE RGN. THE POOR CONDITIONS WL CONT FOR MOST OF FRIDAY.
SKOWRONSKI
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 3 AM TO 3 PM CST FRIDAY FOR
WIZ037>039-048-049.
WINTER WEATHER ADVISORY UNTIL 3 PM CST FRIDAY FOR WIZ040-050.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST FRIDAY
FOR WIZ011>013-019>021-030-031.
WINTER WEATHER ADVISORY UNTIL NOON CST FRIDAY FOR WIZ005-010-018.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM CST FRIDAY
FOR WIZ022-073-074.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS GREEN BAY WI
615 PM CST THU JAN 24 2013
.UPDATE...DONT LIKE AT ALL THE WAY THE SITN IS EVOLVING THIS
EVENING. LOW-LEVELS REMAIN VERY DRY...AND SLY FLOW AHEAD OF THE
INCOMING SYSTEM WL CONT TO REINFORCE THE DRY AIR FM THE S. THAT
COULD PLAY HAVOC WITH THE ONSET OF PCPN...THE TIMING OF THE
ADVISORY...AND SNOW AMNTS. RAP PAINTING A MUCH DIFFERENT PICTURE
THAN THE REST OF THE GUID. IT HAS BAND OF SNOW IN ISENT LIFT ZONE
TRYING TO CONSOLIDATE AS IT WORKS ACRS THE FCST AREA THIS EVENING.
BUT THEN THAT BAND PUSHES OFF TO THE E AFTER MIDNIGHT...WITH AT
LEAST A SEVERAL HR LULL IN THE PCPN BEFORE LOW-LEVELS SATURATE
AGAIN AND PCPN WITH THE UPR SHRTWV ARRIVES. IT/S RATHER HARD TO
ARGUE WITH THAT IDEA GIVEN THE CURRENT RADAR TRENDS...AND THE VERY
LIMITED NUMBER OF OB SITES REPORTING SNOW IN MN/NW WI EARLY THIS
EVENING. NOT READY TO MAKE ANY SIG CHGS TO THE FCST YET... THOUGH
THAT MAY BECOME NECESSARY IF CURRENT RADAR/OB TRENDS HOLD.
ONE AREA THAT COULD SEE SNOW A LITTLE EARLIER THAN EXPECTED IS THE
LAKESHORE RGN OF MTW COUNTY. MESOSCALE CIRCULATION WORKING NWD
OVER WRN LAKE MICHIGAN COULD GET SOME SHSN AND FLURRIES INTO
LAKESHORE AREAS DURING THE EVENING.
GOING TO UPDATE THE FCST FOR THE LAKE-EFFECT NOW...BUT HOLD OFF
MAKING ANY MORE SUBSTANTIAL CHGS FOR NOW.
SKOWRONSKI
&&
.PREV DISCUSSION...ISSUED AT 541 PM CST THU JAN 24 2013...
SHORT TERM...TONIGHT AND FRIDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH
PRESSURE CENTERED ACROSS THE STATE EARLY THIS AFTERNOON. MID AND
HIGH CLOUDS ARE ALREADY ON THE INCREASE...HOWEVER...AHEAD OF THE
NEXT SHORTWAVE TROUGH MOVING ESE OVER SOUTHERN SASKATCHEWAN. RADARS
ARE PUSHING AN AREA OF LIGHT TO MODERATE SNOW OVER FAR NORTHERN
NORTH DAKOTA AND SOUTHERN MANITOBA AND IS STARTING TO ENTER NORTHERN
MINNESOTA. AS THE SHORTWAVE TRACKS TOWARDS THE REGION TONIGHT AND
OVER THE REGION ON FRIDAY...SNOWFALL AMOUNTS AND HEADLINES ARE THE MAIN
FORECAST CONCERNS.
TONIGHT...SHORTWAVE TROUGH OVER THE SOUTHERN CANADIAN PRAIRIE WILL
DIVE SOUTHEAST TONIGHT ON ITS WAY TO THE ARROWHEAD OF MINNESOTA BY
12Z FRIDAY. AHEAD OF THE SHORTWAVE...FORCING IN THE FORM OF DPVA
AND ISENTROPIC ASCENT ON THE 280-285K SURFACES WILL SPREAD SOUTHEAST
WHICH WILL LEAD TO A WARM ADVECTION BAND ENTERING NW WISCONSIN BY
00-03Z AND NORTH-CENTRAL AND NORTHEAST WISCONSIN IN THE 03-06Z TIME
PERIOD. PLENTY OF UNCERTAINTY WITH THE DETAILS...INCLUDING WHERE
AND WHEN THE BAND ENTERS THE FORECAST AREA...AND ALSO SNOWFALL
RATIOS. THE LATEST SHORTER RANGE GUIDANCE INDICATES THAT A WARM
ADVECTION SNOW BAND WILL DIVE SE INTO RHI-GRB LINE BETWEEN 03-06Z
BEFORE WIDESPREAD SNOW ENTERS THE AREA AFTER MIDNIGHT. FGEN AND
INSTABILITY ALOFT ARE NOT PARTICULARLY IMPRESSIVE...BUT MICROPHYSICS
ARE A DIFFERENT STORY. BUFKIT SOUNDINGS FOR THE BOTH THE NAM/GFS
INDICATE AN ISOTHERMAL LAYER FROM THE SURFACE TO ABOUT
575MB...FIRMLY IN THE DENDRITIC GROWTH ZONE. ASCENT WONT OCCUPY
THIS ENTIRE LAYER...BUT SHOULD COINCIDE FOR ABOUT 200MB FROM LATE
THIS EVENING THROUGH EARLY FRIDAY MORNING. AS A RESULT...DESPITE
MEDIOCRE FORCING AND INSTABILITY...SHOULDNT TAKE MUCH QPF IN ORDER
TO GET A SUBSTANTIAL AMOUNT OF SNOW. ESTIMATING SNOWFALL RATIOS OF
20-30:1 WILL YIELD WIDESPREAD 2-4 INCH AMOUNTS BY MORNING FROM
NORTH-CENTRAL WISCONSIN TO THE SOUTHERN FOX VALLEY. WILL ADD
WAUPACA AND THE REST OF THE FOX VALLEY/LAKESHORE TO THE WINTER
WEATHER ADVISORY SINCE THE SNOW WILL BE FLYING DURING THE MORNING
RUSH HOURS WHERE 2-3 INCHES WILL PROBABLY ALREADY HAVE FALLEN. WILL
ALSO BUMP UP THE START TIME OVER N-C WISCONSIN TO START IT AT 03Z.
FRIDAY...THE SHORTWAVE WILL PASS ACROSS THE AREA DURING THE
DAY...AND IT WILL PUSH A SURFACE LOW ACROSS NORTHERN WISCONSIN
DURING THE AFTERNOON. FORCING WILL BE SHIFTING TO THE SOUTHEAST
FRIDAY MORNING...WHICH MAY LEAD TO SOME DRY SLOTTING OVER CENTRAL
AND EAST-CENTRAL WISCONSIN. BUT DEEPER COMMA HEAD MOISTURE DOES PASS
OVER NORTH-CENTRAL AND NORTHEAST WISCONSIN DURING THE DAY...WHERE
HIGHER ACCUMS SHOULD RESIDE. WILL STILL HAVE THE VERY GOOD SNOW
RATIOS FOR MUCH OF THE DAY...AND CAN SEE ADDITIONAL 1-2 INCHES OVER
NORTHEAST HALF OF THE FORECAST AREA...AND LESS THAN AN INCH OVER THE
SOUTHWEST. WINDS MAY START TO GET GUSTY LATE IN THE
AFTERNOON...WHICH MAY LEAD TO MINOR BLOWING AND DRIFTING SNOW.
HIGHS IN THE MID TEENS TO MID 20S.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
CLIPPER SYSTEM WILL CONTINUE TO MOVE AWAY FROM THE AREA FRIDAY
NIGHT. COULD BE A BRIEF PERIOD OF GUSTY WINDS AND BLOWING AND
DRIFTING OF THE SNOW AS SYSTEM MOVES AWAY AND COLDER AIR FILTERS
INTO THE REGION. WILL MENTION IT IN THE HAZARDOUS WEATHER OUTLOOK...
BUT WILL NOT HAVE IT IN THE GRIDS DUE TO THE BRIEF NATURE OF THE
EVENT. OTHERWISE...LAKE EFFECT SNOW SHOWERS WILL CONTINUE THROUGH
MOST OF THE NIGHT ACROSS THE FAR NORTH. HAVE INCREASED POPS INTO
THE CATEGORICAL RANGE FOR VILAS COUNTY AND INCREASED POPS OVER
THE REMAINDER OF THE NORTH AS WELL. DID ADD A CHANCE OF FLURRIES
THROUGH MOST OF THE NIGHT ACROSS THE SOUTH UNTIL CLEARING ARRIVES.
DID SLOW THE ARRIVAL OF THE CLEARING BY SEVERAL HOURS...MAINLY DUE
TO COLD NORTHERLY FLOW OFF THE WARMER WATERS OF LAKE SUPERIOR.
MODELS DO SHOW DRYING OF THE 850MB MOISTURE TOWARDS 12Z ACROSS
CENTRAL WISCONSIN. ON SATURDAY...DID LEAVE A FEW LINGERING FLURRIES
FOR A FEW HOURS SATURDAY MORNING ACROSS THE FAR NORTH/NORTHEAST.
WITH SUCH A COLD AIR MASS IN PLACE...ANY CUMULUS CLOUD COULD PRODUCE
A FEW FLURRIES BEFORE DISSIPATING.
NEW QUESTIONS ARISE FOR THE SATURDAY NIGHT PERIOD. LATEST WRF/CANADIAN
NOW PRODUCE A FEW INCHES OF LIGHT SNOW ACROSS CENTRAL AND NORTHERN
WISCONSIN...WHILE THE GFS/ECMWF DO NOT SHOW THIS FEATURE. WILL HAVE
A SLIGHT CHANCE OF LIGHT SNOW ACROSS THE NORTH FOR NOW.
CONFIDENCE REMAINS LOW THROUGHOUT THE REST OF THE FORECAST PERIOD
WITH HANDLING OF SYSTEM SUNDAY NIGHT AND SUNDAY NIGHT...AND AGAIN
TUESDAY. LATEST CANADIAN/ECMWF MODELS HAVE SHIFTED SYSTEM SUNDAY/
SUNDAY NIGHT FURTHER SOUTH AND WOULD JUST CLIP OUR FAR SOUTH. SINCE
MODELS HAVE BEEN JUMPING AROUND SIGNIFICANT ON LOCATION OF THIS SYSTEM...
WILL CONTINUE WITH PERSISTENCE FOR NOW UNTIL THERE IS A CLEAR
TREND. PRECIPITATION TYPE ISSUES STILL CONTINUE WITH THIS SYSTEM
WILL PRECIPITATION COULD END UP AS LIGHT SNOW...FREEZING RAIN OR
SLEET.
THE SYSTEM FOR TUESDAY CONTINUE TO BE PROBLEMATIC AS THE ECMWF
CONTINUES TO GO BACK AND FORTH WITH SURFACE LOW TRACKING WEST OF
GREEN BAY. THE GFS CONTINUED THIS TREND ON THE MORNING RUN...BUT 12Z
ECMWF HAS NO SUCH FEATURE ON THIS RUN. WILL CONTINUE WITH PERSISTENCE
WITH THIS PERIOD AS WELL UNTIL MODELS CONVERGE ON A CLEAR SOLUTION.
AT OR ABOVE NORMAL TEMPERATURES ARE EXPECTED MONDAY AND TUESDAY...THEN
BELOW NORMAL TEMPERATURES ARE EXPECTED LATE NEXT WEEK AS ANOTHER
SURGE OF ARCTIC AIR WILL SWEEP INTO THE NORTHERN UNITED STATES.
&&
.AVIATION...FOR 00Z TAF ISSUANCE. VFR CONDITIONS EARLY THIS
EVENING WL WORSEN TO LOWER END MVFR OR IFR BY LATE TNGT AS SNOW
MVS INTO THE RGN. THE POOR CONDITIONS WL CONT FOR MOST OF FRIDAY.
SKOWRONSKI
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM CST FRIDAY
FOR WIZ022-037>040-048>050-073-074.
WINTER WEATHER ADVISORY UNTIL NOON CST FRIDAY FOR WIZ005-010>013-
018>021-030-031.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
541 PM CST THU JAN 24 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND FRIDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH
PRESSURE CENTERED ACROSS THE STATE EARLY THIS AFTERNOON. MID AND
HIGH CLOUDS ARE ALREADY ON THE INCREASE...HOWEVER...AHEAD OF THE
NEXT SHORTWAVE TROUGH MOVING ESE OVER SOUTHERN SASKATCHEWAN. RADARS
ARE PUSHING AN AREA OF LIGHT TO MODERATE SNOW OVER FAR NORTHERN
NORTH DAKOTA AND SOUTHERN MANITOBA AND IS STARTING TO ENTER NORTHERN
MINNESOTA. AS THE SHORTWAVE TRACKS TOWARDS THE REGION TONIGHT AND
OVER THE REGION ON FRIDAY...SNOWFALL AMOUNTS AND HEADLINES ARE THE MAIN
FORECAST CONCERNS.
TONIGHT...SHORTWAVE TROUGH OVER THE SOUTHERN CANADIAN PRAIRIE WILL
DIVE SOUTHEAST TONIGHT ON ITS WAY TO THE ARROWHEAD OF MINNESOTA BY
12Z FRIDAY. AHEAD OF THE SHORTWAVE...FORCING IN THE FORM OF DPVA
AND ISENTROPIC ASCENT ON THE 280-285K SURFACES WILL SPREAD SOUTHEAST
WHICH WILL LEAD TO A WARM ADVECTION BAND ENTERING NW WISCONSIN BY
00-03Z AND NORTH-CENTRAL AND NORTHEAST WISCONSIN IN THE 03-06Z TIME
PERIOD. PLENTY OF UNCERTAINTY WITH THE DETAILS...INCLUDING WHERE
AND WHEN THE BAND ENTERS THE FORECAST AREA...AND ALSO SNOWFALL
RATIOS. THE LATEST SHORTER RANGE GUIDANCE INDICATES THAT A WARM
ADVECTION SNOW BAND WILL DIVE SE INTO RHI-GRB LINE BETWEEN 03-06Z
BEFORE WIDESPREAD SNOW ENTERS THE AREA AFTER MIDNIGHT. FGEN AND
INSTABILITY ALOFT ARE NOT PARTICULARLY IMPRESSIVE...BUT MICROPHYSICS
ARE A DIFFERENT STORY. BUFKIT SOUNDINGS FOR THE BOTH THE NAM/GFS
INDICATE AN ISOTHERMAL LAYER FROM THE SURFACE TO ABOUT
575MB...FIRMLY IN THE DENDRITIC GROWTH ZONE. ASCENT WONT OCCUPY
THIS ENTIRE LAYER...BUT SHOULD COINCIDE FOR ABOUT 200MB FROM LATE
THIS EVENING THROUGH EARLY FRIDAY MORNING. AS A RESULT...DESPITE
MEDIOCRE FORCING AND INSTABILITY...SHOULDNT TAKE MUCH QPF IN ORDER
TO GET A SUBSTANTIAL AMOUNT OF SNOW. ESTIMATING SNOWFALL RATIOS OF
20-30:1 WILL YIELD WIDESPREAD 2-4 INCH AMOUNTS BY MORNING FROM
NORTH-CENTRAL WISCONSIN TO THE SOUTHERN FOX VALLEY. WILL ADD
WAUPACA AND THE REST OF THE FOX VALLEY/LAKESHORE TO THE WINTER
WEATHER ADVISORY SINCE THE SNOW WILL BE FLYING DURING THE MORNING
RUSH HOURS WHERE 2-3 INCHES WILL PROBABLY ALREADY HAVE FALLEN. WILL
ALSO BUMP UP THE START TIME OVER N-C WISCONSIN TO START IT AT 03Z.
FRIDAY...THE SHORTWAVE WILL PASS ACROSS THE AREA DURING THE
DAY...AND IT WILL PUSH A SURFACE LOW ACROSS NORTHERN WISCONSIN
DURING THE AFTERNOON. FORCING WILL BE SHIFTING TO THE SOUTHEAST
FRIDAY MORNING...WHICH MAY LEAD TO SOME DRY SLOTTING OVER CENTRAL
AND EAST-CENTRAL WISCONSIN. BUT DEEPER COMMA HEAD MOISTURE DOES PASS
OVER NORTH-CENTRAL AND NORTHEAST WISCONSIN DURING THE DAY...WHERE
HIGHER ACCUMS SHOULD RESIDE. WILL STILL HAVE THE VERY GOOD SNOW
RATIOS FOR MUCH OF THE DAY...AND CAN SEE ADDITIONAL 1-2 INCHES OVER
NORTHEAST HALF OF THE FORECAST AREA...AND LESS THAN AN INCH OVER THE
SOUTHWEST. WINDS MAY START TO GET GUSTY LATE IN THE
AFTERNOON...WHICH MAY LEAD TO MINOR BLOWING AND DRIFTING SNOW.
HIGHS IN THE MID TEENS TO MID 20S.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
CLIPPER SYSTEM WILL CONTINUE TO MOVE AWAY FROM THE AREA FRIDAY
NIGHT. COULD BE A BRIEF PERIOD OF GUSTY WINDS AND BLOWING AND
DRIFTING OF THE SNOW AS SYSTEM MOVES AWAY AND COLDER AIR FILTERS
INTO THE REGION. WILL MENTION IT IN THE HAZARDOUS WEATHER OUTLOOK...
BUT WILL NOT HAVE IT IN THE GRIDS DUE TO THE BRIEF NATURE OF THE
EVENT. OTHERWISE...LAKE EFFECT SNOW SHOWERS WILL CONTINUE THROUGH
MOST OF THE NIGHT ACROSS THE FAR NORTH. HAVE INCREASED POPS INTO
THE CATEGORICAL RANGE FOR VILAS COUNTY AND INCREASED POPS OVER
THE REMAINDER OF THE NORTH AS WELL. DID ADD A CHANCE OF FLURRIES
THROUGH MOST OF THE NIGHT ACROSS THE SOUTH UNTIL CLEARING ARRIVES.
DID SLOW THE ARRIVAL OF THE CLEARING BY SEVERAL HOURS...MAINLY DUE
TO COLD NORTHERLY FLOW OFF THE WARMER WATERS OF LAKE SUPERIOR.
MODELS DO SHOW DRYING OF THE 850MB MOISTURE TOWARDS 12Z ACROSS
CENTRAL WISCONSIN. ON SATURDAY...DID LEAVE A FEW LINGERING FLURRIES
FOR A FEW HOURS SATURDAY MORNING ACROSS THE FAR NORTH/NORTHEAST.
WITH SUCH A COLD AIR MASS IN PLACE...ANY CUMULUS CLOUD COULD PRODUCE
A FEW FLURRIES BEFORE DISSIPATING.
NEW QUESTIONS ARISE FOR THE SATURDAY NIGHT PERIOD. LATEST WRF/CANADIAN
NOW PRODUCE A FEW INCHES OF LIGHT SNOW ACROSS CENTRAL AND NORTHERN
WISCONSIN...WHILE THE GFS/ECMWF DO NOT SHOW THIS FEATURE. WILL HAVE
A SLIGHT CHANCE OF LIGHT SNOW ACROSS THE NORTH FOR NOW.
CONFIDENCE REMAINS LOW THROUGHOUT THE REST OF THE FORECAST PERIOD
WITH HANDLING OF SYSTEM SUNDAY NIGHT AND SUNDAY NIGHT...AND AGAIN
TUESDAY. LATEST CANADIAN/ECMWF MODELS HAVE SHIFTED SYSTEM SUNDAY/
SUNDAY NIGHT FURTHER SOUTH AND WOULD JUST CLIP OUR FAR SOUTH. SINCE
MODELS HAVE BEEN JUMPING AROUND SIGNIFICANT ON LOCATION OF THIS SYSTEM...
WILL CONTINUE WITH PERSISTENCE FOR NOW UNTIL THERE IS A CLEAR
TREND. PRECIPITATION TYPE ISSUES STILL CONTINUE WITH THIS SYSTEM
WILL PRECIPITATION COULD END UP AS LIGHT SNOW...FREEZING RAIN OR
SLEET.
THE SYSTEM FOR TUESDAY CONTINUE TO BE PROBLEMATIC AS THE ECMWF
CONTINUES TO GO BACK AND FORTH WITH SURFACE LOW TRACKING WEST OF
GREEN BAY. THE GFS CONTINUED THIS TREND ON THE MORNING RUN...BUT 12Z
ECMWF HAS NO SUCH FEATURE ON THIS RUN. WILL CONTINUE WITH PERSISTENCE
WITH THIS PERIOD AS WELL UNTIL MODELS CONVERGE ON A CLEAR SOLUTION.
AT OR ABOVE NORMAL TEMPERATURES ARE EXPECTED MONDAY AND TUESDAY...THEN
BELOW NORMAL TEMPERATURES ARE EXPECTED LATE NEXT WEEK AS ANOTHER
SURGE OF ARCTIC AIR WILL SWEEP INTO THE NORTHERN UNITED STATES.
&&
.AVIATION...FOR 00Z TAF ISSUANCE. VFR CONDITIONS EARLY THIS
EVENING WL WORSEN TO LOWER END MVFR OR IFR BY LATE TNGT AS SNOW
MVS INTO THE RGN. THE POOR CONDITIONS WL CONT FOR MOST OF FRIDAY.
SKOWRONSKI
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM CST FRIDAY
FOR WIZ022-037>040-048>050-073-074.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO NOON CST
FRIDAY FOR WIZ005-010>013-018>021-030-031.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
232 PM CST WED JAN 23 2013
.SHORT TERM...TONIGHT AND THURSDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A COMPACT
SHORTWAVE DIVING SOUTHEAST OVER THE ARROWHEAD OF MINNESOTA EARLY
THIS AFTERNOON...WHICH IS HELPING TO PUSH ALONG A SURFACE LOW OVER
SOUTHERN LAKE SUPERIOR. AHEAD OF THE SHORTWAVE...A COMBINATION OF
DPVA AND ISENTROPIC ASCENT IS CONTRIBUTING TO OCCASIONAL LIGHT SNOW
ACROSS MUCH OF THE STATE OF WISCONSIN. BEHIND THE
SHORTWAVE...ANOTHER SURGE OF ARCTIC AIR IS SLIDING SOUTHEAST...WITH
TEMPERATURES FALLING OVER NORTHERN MINNESOTA...AND WINDS GUSTING
INTO THE 30-35 MPH RANGE. PLENTY OF CONCERNS IN THE SHORT
TERM...INCLUDING LIGHT SNOW...WIND...AND WIND CHILL ISSUES.
TONIGHT...THE SHORTWAVE TROUGH WILL BE OVERHEAD AT THE START OF THE
EVENING BEFORE DEPARTING BY MIDNIGHT. SOME SNOW SHOWERS ARE
DIURNALLY ENHANCED...BUT THINK WILL SEE SNOW SHOWERS LINGER EARLY
THIS EVENING WITHIN THE LATEST REINFORCING SURGE OF ARCTIC AIR.
BEHIND THE SHORTWAVE...LOW LEVEL WINDS WILL TURN TO THE NNW AND
BECOME GUSTY FOR A PERIOD THIS EVENING. COULD SEE SOME GUSTS UP TO
30 MPH. THE WIND DIRECTION WILL ALSO INCREASE LAKE EFFECT POTENTIAL
WITHIN THE SNOW BELTS OF N-C WISCONSIN. 850MB TEMPS IN THE MID 20S
BELOW ZERO ARE NOT CONDUCIVE FOR GOOD ACCUMULATIONS (TALCUM POWDER
SNOW)...BUT UP TO AN INCH OVER THE NW PART OF VILAS COUNTY LOOKS
POSSIBLE. POTENTIAL WOULD BE THERE FOR MORE ACCUMS IF THE WIND
DIRECTION DIDNT TURN DUE NORTH AFTER MIDNIGHT. ARCTIC HIGH PRESSURE
WILL BE BUILDING SE INTO THE WESTERN GREAT LAKES AFTER MIDNIGHT AS
WELL WHICH WILL CONTRIBUTE TO CLEARING SKIES. WINDS WILL BE
DIMINISHING RATHER QUICKLY AND WILL LIKELY GO LIGHT AND VARIABLE
LATE TONIGHT. THIS WILL SET UP CONCERNS FOR WIND CHILL HEADLINES.
PROJECTED WIND CHILL VALUES FALL TO 20-25 BELOW BY 02Z OVER CENTRAL
AND NORTH-CENTRAL WISCONSIN WHERE THEY WILL REMAIN UNTIL LATE
TONIGHT WHEN WINDS DROP OFF. SO THIS SETS UP A WEIRD SCENARIO WHERE
WIND CHILLS WILL BE THE COLDEST DURING THE LATE EVENING AND EARLY
OVERNIGHT HOURS...BEFORE IMPROVING AS WINDS TURN CALM. WITH COORD
FROM OTHER OFFICES...WILL RUN A WIND ADVISORY FROM 02Z THROUGH 12Z
THU. POTENTIAL WILL BE THERE TO CANCEL EARLY IF WINDS DO TURN CALM.
LOWS FROM 15 BELOW OVER NORTH-CENTRAL WISCONSIN TO AROUND 0 DEGREES
NEAR LAKE MICHIGAN.
THURSDAY...ARCTIC HIGH PRESSURE WILL BE CENTERED ACROSS THE REGION.
ANY LINGERING LAKE EFFECT SNOW SHOWERS WILL BE ENDING THURSDAY
MORNING AS WINDS TURN LIGHT AND BACK AROUND TO THE WEST. OTHERWISE
WILL SEE A GOOD DEAL OF SUNSHINE. CIRRUS WILL BE INCREASING DURING
THE AFTERNOON...BUT MORE SUNSHINE AND LOW LEVEL TEMPS SLIGHTLY
WARMER THAN TODAY SHOULD GIVE TEMPS A DEGREE OR TWO WARMER IN MOST
LOCATIONS. HIGHS FROM THE UPPER SINGLE DIGITS NORTH TO THE MID
TEENS NEAR LAKE MICHIGAN.
.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY.
ALBERTA CLIPPER EXPECTED TO SWING ACROSS THE WESTERN LAKES
THURSDAY NIGHT INTO FRIDAY. SNOW IS EXPECTED TO SPREAD INTO
NORTHERN MINNESOTA THURSDAY AFTERNOON AND THEN OVERSPREAD THE
FORECAST AREA THURSDAY NIGHT. STILL SOME DIFFERENCES WITH THE
ONSET OF THE TIMING OF THE SNOW BETWEEN THE GFS/WRF...BUT TRENDED
TOWARD THE QUICKER GFS/CANADIAN/ECMWF SOLUTION DUE TO COLD AIR MASS
IN PLACE AND QUICKER SATURATION OF THE ATMOSPHERE. WENT WITH SNOW
AFTER MIDNIGHT. ACCUMULATIONS SHOULD RANGE FROM 1 TO 3 INCHES
ACROSS THE SOUTHWEST TO 2 TO 4 INCHES OVER NORTH-CENTRAL AND
NORTHEAST WISCONSIN. WILL NEED TO WATCH DOOR COUNTY AS 925MB WINDS
TURN TO THE SOUTH LATE THURSDAY NIGHT INTO FRIDAY MORNING. COULD
SEE SOME LAKE EFFECT SNOW SHOWERS/LAKE ENHANCEMENT ACROSS NORTHERN
DOOR COUNTY. LIGHT SNOW WILL CONTINUE INTO FRIDAY MORNING BEFORE
TAPERING OFF TO SCATTERED SNOW SHOWERS OR FLURRIES FRIDAY AFTERNOON.
AROUND AN INCH ADDITIONAL ACCUMULATION IS EXPECTED...BRINGING THE
TOTAL STORM ACCUMULATIONS OF 2 TO 4 INCHES ACROSS THE SOUTHWEST
PORTION OF THE FORECAST AREA WITH 3 TO 5 INCHES ELSEWHERE. LOCALLY
HIGHER AMOUNTS ARE POSSIBLE ACROSS NORTHERN DOOR COUNTY DUE TO LAKE
ENHANCEMENT/LAKE EFFECT POTENTIAL.
COLDER AIR WILL WORK INTO THE REGION FRIDAY NIGHT. COULD BE SOME GUSTY
WINDS BEHIND DEPARTING SYSTEM THAT COULD PRODUCE SOME BLOWING AND
DRIFTING SNOW. WILL MENTION IN THE HAZARDOUS WEATHER OUTLOOK. ANOTHER
SURGE OF ARCTIC AIR WILL PLUNGE INTO THE AREA BY SATURDAY MORNING
WITH TEMPERATURES A FEW DEGREES BELOW ZERO ACROSS CENTRAL WISCONSIN
AND NEAR 5 ABOVE ALONG THE LAKE.
FORECAST CONFIDENCE WANES QUICKLY SUNDAY INTO THE MIDDLE OF NEXT WEEK.
FIRST SYSTEM FOR SUNDAY INTO MONDAY. NEW ECMWF CONTINUES TO BRING BRUNT
OF THE SYSTEM SOUTH OF THE AREA WITH ONLY PRECIPITATION UP TO HIGHWAY
29. THE GFS/CANADIAN WOULD SUPPORT AN ACCUMULATING SNOW SUNDAY INTO
MONDAY. WILL CONTINUE WITH PREVIOUS FORECAST AS I SUSPECT THE
ECMWF WILL SHIFT SYSTEM A LITTLE FURTHER NORTH.
THE NEXT SYSTEM EARLY NEXT WEEK CONTINUES TO BE PROBLEMATIC AS
WELL. THE CANADIAN/GFS DO NOT BRING SYSTEM UP ALONG THE ARCTIC
BOUNDARY. THE 12Z ECMWF WOULD BRING A FAIRLY POTENT SYSTEM FOR
MONDAY NIGHT INTO TUESDAY THAT WOULD BRING AN ONSET OF SNOW...FREEZING
RAIN BEFORE CHANGING OVER TO RAIN OR FREEZING RAIN. DID NOT
INTRODUCE FREEZING RAIN AT THIS TIME SINCE THERE WAS UNCERTAINTY
IF THIS STORM WOULD ACTUALLY EXIST. OTHERWISE...ARCTIC AIR IS
EXPECTED TO LINGER ALONG THE UNITED STATES/CANADIAN BORDER THROUGH
THE END OF NEXT WEEK. HOW MUCH OF THIS ARCTIC INTRUSION WILL
FILTER INTO NORTHEAST WISCONSIN IS STILL QUESTIONABLE...BUT IT
APPEARS THAT BELOW NORMAL TEMPERATURES CAN BE EXPECTED THROUGH
MUCH OF THE PERIOD...EXCEPT FOR THE POSSIBILITY OF TUESDAY IF
ECMWF IS CORRECT.
&&
.AVIATION...CLIPPER TYPE SYSTEM FROM SOUTHWEST ONTARIO WILL PASS
ACROSS THE AREA THIS AFTERNOON. LIGHT SNOW IS POSSIBLE ACROSS THE
ENTIRE REGION...WITH POTENTIAL TO DROP VSBYS TO 1SM OR 1 1/2SM
WITHIN A HIGH END MVFR CLOUD DECK. THE CLIPPER WILL EXIT THIS
EVENING...WHICH WILL BRING SNOW SHOWERS TO AN END AND GRADUAL
CLEARING TO CENTRAL AND NORTHEAST WISCONSIN. CLOUDS WILL TAKE
LONGER TO DEPART OVER NORTH-CENTRAL WISCONSIN WHERE WINDS WILL BE
NORTHWEST OFF LAKE SUPERIOR. SOME GUSTY NORTHWEST WINDS ARE
POSSIBLE LATE THIS AFTERNOON INTO THIS EVENING...THEN WINDS DIMINISH
TO CALM AFTER MIDNIGHT. GENERALLY VFR CONDITIONS UNDER MOSTLY CLEAR
SKY LATE TONIGHT INTO EARLY AFTERNOON ON THURSDAY.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 6 AM CST THURSDAY
FOR WIZ005-010-011-018-019-030-035-036.
&&
$$
MPC/ECKBERG
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1116 AM CST WED JAN 23 2013
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
316 AM CST WED JAN 23 2013
THERE ARE SEVERAL AREAS OF CONCERNS THROUGH THE SHORT TERM. FIRST
DEALS WITH LIGHT SNOW ACROSS SOUTHEAST MN...NORTHEAST IA AND FAR
SOUTHWEST WI TODAY. SECONDLY...WIND CHILLS THIS EVENING THROUGH
THURSDAY MORNING...AND FINALLY...LIKELIHOOD OF ACCUMULATING SNOW
THURSDAY NIGHT INTO FRIDAY.
WATER VAPOR RAP 500MB ANALYSIS SHOWS WELL ESTABLISHED SOUTHERN
EXTENSION OF THE POLAR VORTEX ACROSS THE AREA WITH NORTHWEST FLOW
BRINGING IN A SHORTWAVE TROUGH CURRENTLY EXTENDING FROM NORTHWEST WI
INTO NORTHWEST IA. 850-700MB WAA/ISENTROPIC LIFT PER THE RAP WAS
PRODUCING A BAND OF MOSTLY 7-10SM FLURRIES WITH POCKETS OF 4/5SM -SN
EXTENDING FROM SOUTHWEST MN INTO NORTH CENTRAL IA.
NAM SEEMS THE ODD MODEL OUT WITH THE SYSTEM COMING THROUGH THU N/FRI
WITH ITS FARTHER NORTH SOLUTION...AND PRETTY MUCH DISCOUNTED FOR
NOW. THE GFS/EC/GEM REMAIN IN PRETTY GOOD AGREEMENT AND THEREFORE
USING A CONSENSUS OF THESE MODELS.
FOR TODAY...MODELS CONTINUE TO SHOW GOOD 850-700MB WAA AND WEAK
270-280K WEAK ISENTROPIC UPGLIDE FROM SOUTHEAST MN INTO FAR
SOUTHWEST WI THROUGH THIS MORNING...SHIFTING SOUTHEAST OF THE AREA
BY AFTERNOON. BUMPED POPS INTO CATEGORICAL RANGE BASED ON THIS
FOCUSED FORCING SIGNAL SOUTH OF A LINE FROM DODGE CENTER AND
ROCHESTER MN THROUGH BOSCOBEL WI WHERE UP TO A HALF INCH OF SNOWFALL
IS POSSIBLE. FOR THIS AFTERNOON...COLD AIR ADVECTION BEHIND THE
SHORTWAVE TROUGH AND FAIRLY STEEP LOW LEVEL LAPSE RATES MAY LEAD TO
SOME FLURRY ACTIVITY ACROSS THE ENTIRE AREA. OTHERWISE...
TEMPERATURES WILL BE A BIT MILDER //RELATIVELY SPEAKING// TODAY WITH
HIGHS IN THE 10 TO 23 DEGREE RANGE. NORTHWEST WINDS WILL ALSO BE ON
THE INCREASE THIS AFTERNOON BEHIND THE WAVE.
BRISK NORTHWEST WINDS EXPECTED TO CONTINUE INTO THIS EVENING AS
TEMPERATURES START THE DOWNWARD TUMBLE INTO THE SINGLE DIGITS BELOW
ZERO RANGE ACROSS THE NORTHWEST PORTION OF THE FORECAST AREA. LOW
TEMPERATURES TONIGHT EXPECTED TO BOTTOM OUT IN THE MINUS 5 TO MINUS 10
DEGREE RANGE NORTHWEST OF A LINE FROM MEDFORD WI/BLACK RIVER
FALLS...THROUGH WINONA TO PRESTON MN AND OELWEIN IA WITH WIND CHILL
VALUES DIPPING INT THE 20-25 DEGREE RANGE. THEREFORE...WILL BE GOING
WITH A WIND CHILL ADVISORY FROM 8 PM THIS EVENING THROUGH 9 AM
THURSDAY FOR AREAS NORTHWEST OF THIS LINE.
ATTENTION THEN TURNS TO A FAIRLY VIGOROUS MID-LEVEL SHORTWAVE
TROUGH/SURFACE LOW DROPPING SOUTHEAST OUT OF ALBERTA CANADA INTO THE
DAKOTAS BY THURSDAY AFTERNOON...AND ACROSS CENTRAL WISCONSIN BY
FRIDAY MORNING. MODELS CONTINUE TO SHOWING FAIRLY STRONG N-S WING OF
850-700MB WAA/ISENTROPIC LIFT INTO THE AREA THURSDAY NIGHT AHEAD OF
THE WAVE INTO OUR AREA. THIS SIGNAL HAS BEEN INCREASING IN
CONSISTENCY FRO THE LIKELIHOOD OF SOME ACCUMULATING SNOW FOR THE
AREA. RIGHT NOW...IT APPEARS ANYWHERE FROM 1 TO 3 INCHES LOOKS
PRETTY LIKELY WITH THE HIGHER-END AMOUNTS ALONG AND NORTH OF THE
I-94 CORRIDOR. OTHERWISE...LOOKING FOR HIGHS ON THURSDAY IN THE
TEENS AND LOWS THURSDAY NIGHT IN THE SINGLE DIGITS TO TEENS ABOVE
ZERO.
SOME LINGERING DEFORMATION SNOW LOOKS LIKELY MAINLY THROUGH FRIDAY
MORNING AS THE LOW DIVES INTO LOWER MICHIGAN WITH PERHAPS AN
ADDITIONAL HALF TO ONE INCH POSSIBLE. SKIES CLEAR FRIDAY NIGHT WITH
LOWS DROPPING OFF INTO THE SINGLE DIGITS BELOW TO SINGLE DIGITS
ABOVE ZERO AS HIGH PRESSURE BUILDS IN FROM THE DAKOTAS.
.LONG TERM...SATURDAY THROUGH TUESDAY
316 AM CST WED JAN 23 2013
23.00Z GFS/ECMWF IN FAIRLY DECENT AGREEMENT THROUGH THE LONG TERM
PERIOD. HIGH PRESSURE HOLDS ACROSS THE AREA ON SATURDAY FOR MOSTLY
SUNNY SKIES WITH HIGHS EXPECTED TO TOP OFF IN THE TEENS. HIGH
PRESSURE MOVES OFF TO THE EAST SATURDAY NIGHT WITH WAA KICKING IN
AHEAD OF A MID LEVEL TROUGH EJECTING OUT OF THE INTERMOUNTAIN WEST.
THIS SPREADS CLOUD AND A SLIGHT CHANCE OF SNOW INTO THE AREA WEST OF
THE MISSISSIPPI RIVER. FOR SUNDAY THROUGH TUESDAY...LOW PRESSURE
GETS ORGANIZED ON THE LEESIDE OF THE CENTRAL ROCKIES/HIGH PLAINS.
THIS PUTS THE AREA IN BROAD AREA OF ISENTROPIC LIFT/WAA FOR A CHANCE
OF SNOW SUNDAY/SUNDAY NIGHT AND SNOW POSSIBLY MIXING WITH RAIN
MONDAY/TUESDAY DURING THE DAY AS TEMPERATURES WARM INTO THE
MIDDLE/UPPER 30S. WILL HAVE TO MONITOR THIS SYSTEM CLOSELY AS IT HAS
THE POTENTIAL OF BECOMING A FAIRLY STRONG SYSTEM WITH A GOOD AMOUNT
OF PRECIPITATION POSSIBLE.
&&
.AVIATION...THROUGH 18Z THURSDAY
1116 AM CST WED JAN 23 2013
A COLD FRONT HAS PUSHED INTO SOUTHEAST MINNESOTA LATE THIS MORNING
TURNING THE WINDS AROUND TO THE NORTHWEST. EXPECT THIS FRONT WILL
BE THROUGH KRST BEFORE TAF ISSUANCE TIME AND KLSE BY MID
AFTERNOON. STEEP LOW LEVEL LAPSE RATES SET UP BEHIND THE FRONT TO
ALLOW A PERIOD OF GUSTY WINDS TO OCCUR FOR THE AFTERNOON AND MUCH
OF THE EVENING. THE LAPSE RATES DISSIPATE OVERNIGHT AS THE LOW
LEVEL INVERSION SETS UP WITH HIGH PRESSURE BUILDING IN ALSO
ALLOWING THE GRADIENT TO SLACKEN. EXPECT THE GUSTS TO STOP AND
SUSTAINED SPEEDS TO DROP BELOW 10 KNOTS LATE THIS EVENING.
SATELLITE AND SURFACE OBS SUGGESTING MOST OF THE MVFR CLOUDS ARE
AHEAD OF THE FRONT AND ONCE THIS GOES THROUGH...THE CLOUDS SHOULD
SCATTER OUT. HOWEVER...A BAND OF MVFR CLOUDS EXTENDS BACK TOWARD
KULM BEHIND THE FRONT AND IF THIS HOLDS TOGETHER IT WOULD HAVE THE
POTENTIAL TO IMPACT BOTH TAF SITES...SO HAVE INCLUDED THIS
POSSIBILITY THROUGH THE MIDDLE OF THE AFTERNOON. AFTER A PERIOD OF
CLEAR SKIES TONIGHT...HIGH CLOUDS WILL START TO STREAM IN AHEAD OF
THE NEXT SYSTEM AND EXPECT HIGH VFR CEILINGS TO BE IN PLACE BY
LATE THURSDAY MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
316 AM CST WED JAN 23 2013
WI...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST THURSDAY
FOR WIZ017-029-032>034.
MN...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST THURSDAY
FOR MNZ079-086>088-094-095.
IA...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST THURSDAY
FOR IAZ008-009-018-019.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
551 AM CST WED JAN 23 2013
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
316 AM CST WED JAN 23 2013
THERE ARE SEVERAL AREAS OF CONCERNS THROUGH THE SHORT TERM. FIRST
DEALS WITH LIGHT SNOW ACROSS SOUTHEAST MN...NORTHEAST IA AND FAR
SOUTHWEST WI TODAY. SECONDLY...WIND CHILLS THIS EVENING THROUGH
THURSDAY MORNING...AND FINALLY...LIKELIHOOD OF ACCUMULATING SNOW
THURSDAY NIGHT INTO FRIDAY.
WATER VAPOR RAP 500MB ANALYSIS SHOWS WELL ESTABLISHED SOUTHERN
EXTENSION OF THE POLAR VORTEX ACROSS THE AREA WITH NORTHWEST FLOW
BRINGING IN A SHORTWAVE TROUGH CURRENTLY EXTENDING FROM NORTHWEST WI
INTO NORTHWEST IA. 850-700MB WAA/ISENTROPIC LIFT PER THE RAP WAS
PRODUCING A BAND OF MOSTLY 7-10SM FLURRIES WITH POCKETS OF 4/5SM -SN
EXTENDING FROM SOUTHWEST MN INTO NORTH CENTRAL IA.
NAM SEEMS THE ODD MODEL OUT WITH THE SYSTEM COMING THROUGH THU N/FRI
WITH ITS FARTHER NORTH SOLUTION...AND PRETTY MUCH DISCOUNTED FOR
NOW. THE GFS/EC/GEM REMAIN IN PRETTY GOOD AGREEMENT AND THEREFORE
USING A CONSENSUS OF THESE MODELS.
FOR TODAY...MODELS CONTINUE TO SHOW GOOD 850-700MB WAA AND WEAK
270-280K WEAK ISENTROPIC UPGLIDE FROM SOUTHEAST MN INTO FAR
SOUTHWEST WI THROUGH THIS MORNING...SHIFTING SOUTHEAST OF THE AREA
BY AFTERNOON. BUMPED POPS INTO CATEGORICAL RANGE BASED ON THIS
FOCUSED FORCING SIGNAL SOUTH OF A LINE FROM DODGE CENTER AND
ROCHESTER MN THROUGH BOSCOBEL WI WHERE UP TO A HALF INCH OF SNOWFALL
IS POSSIBLE. FOR THIS AFTERNOON...COLD AIR ADVECTION BEHIND THE
SHORTWAVE TROUGH AND FAIRLY STEEP LOW LEVEL LAPSE RATES MAY LEAD TO
SOME FLURRY ACTIVITY ACROSS THE ENTIRE AREA. OTHERWISE...
TEMPERATURES WILL BE A BIT MILDER //RELATIVELY SPEAKING// TODAY WITH
HIGHS IN THE 10 TO 23 DEGREE RANGE. NORTHWEST WINDS WILL ALSO BE ON
THE INCREASE THIS AFTERNOON BEHIND THE WAVE.
BRISK NORTHWEST WINDS EXPECTED TO CONTINUE INTO THIS EVENING AS
TEMPERATURES START THE DOWNWARD TUMBLE INTO THE SINGLE DIGITS BELOW
ZERO RANGE ACROSS THE NORTHWEST PORTION OF THE FORECAST AREA. LOW
TEMPERATURES TONIGHT EXPECTED TO BOTTOM OUT IN THE MINUS 5 TO MINUS 10
DEGREE RANGE NORTHWEST OF A LINE FROM MEDFORD WI/BLACK RIVER
FALLS...THROUGH WINONA TO PRESTON MN AND OELWEIN IA WITH WIND CHILL
VALUES DIPPING INT THE 20-25 DEGREE RANGE. THEREFORE...WILL BE GOING
WITH A WIND CHILL ADVISORY FROM 8 PM THIS EVENING THROUGH 9 AM
THURSDAY FOR AREAS NORTHWEST OF THIS LINE.
ATTENTION THEN TURNS TO A FAIRLY VIGOROUS MID-LEVEL SHORTWAVE
TROUGH/SURFACE LOW DROPPING SOUTHEAST OUT OF ALBERTA CANADA INTO THE
DAKOTAS BY THURSDAY AFTERNOON...AND ACROSS CENTRAL WISCONSIN BY
FRIDAY MORNING. MODELS CONTINUE TO SHOWING FAIRLY STRONG N-S WING OF
850-700MB WAA/ISENTROPIC LIFT INTO THE AREA THURSDAY NIGHT AHEAD OF
THE WAVE INTO OUR AREA. THIS SIGNAL HAS BEEN INCREASING IN
CONSISTENCY FRO THE LIKELIHOOD OF SOME ACCUMULATING SNOW FOR THE
AREA. RIGHT NOW...IT APPEARS ANYWHERE FROM 1 TO 3 INCHES LOOKS
PRETTY LIKELY WITH THE HIGHER-END AMOUNTS ALONG AND NORTH OF THE
I-94 CORRIDOR. OTHERWISE...LOOKING FOR HIGHS ON THURSDAY IN THE
TEENS AND LOWS THURSDAY NIGHT IN THE SINGLE DIGITS TO TEENS ABOVE
ZERO.
SOME LINGERING DEFORMATION SNOW LOOKS LIKELY MAINLY THROUGH FRIDAY
MORNING AS THE LOW DIVES INTO LOWER MICHIGAN WITH PERHAPS AN
ADDITIONAL HALF TO ONE INCH POSSIBLE. SKIES CLEAR FRIDAY NIGHT WITH
LOWS DROPPING OFF INTO THE SINGLE DIGITS BELOW TO SINGLE DIGITS
ABOVE ZERO AS HIGH PRESSURE BUILDS IN FROM THE DAKOTAS.
.LONG TERM...SATURDAY THROUGH TUESDAY
316 AM CST WED JAN 23 2013
23.00Z GFS/ECMWF IN FAIRLY DECENT AGREEMENT THROUGH THE LONG TERM
PERIOD. HIGH PRESSURE HOLDS ACROSS THE AREA ON SATURDAY FOR MOSTLY
SUNNY SKIES WITH HIGHS EXPECTED TO TOP OFF IN THE TEENS. HIGH
PRESSURE MOVES OFF TO THE EAST SATURDAY NIGHT WITH WAA KICKING IN
AHEAD OF A MID LEVEL TROUGH EJECTING OUT OF THE INTERMOUNTAIN WEST.
THIS SPREADS CLOUD AND A SLIGHT CHANCE OF SNOW INTO THE AREA WEST OF
THE MISSISSIPPI RIVER. FOR SUNDAY THROUGH TUESDAY...LOW PRESSURE
GETS ORGANIZED ON THE LEESIDE OF THE CENTRAL ROCKIES/HIGH PLAINS.
THIS PUTS THE AREA IN BROAD AREA OF ISENTROPIC LIFT/WAA FOR A CHANCE
OF SNOW SUNDAY/SUNDAY NIGHT AND SNOW POSSIBLY MIXING WITH RAIN
MONDAY/TUESDAY DURING THE DAY AS TEMPERATURES WARM INTO THE
MIDDLE/UPPER 30S. WILL HAVE TO MONITOR THIS SYSTEM CLOSELY AS IT HAS
THE POTENTIAL OF BECOMING A FAIRLY STRONG SYSTEM WITH A GOOD AMOUNT
OF PRECIPITATION POSSIBLE.
&&
.AVIATION...TODAY AND TONIGHT
551 AM CST WED JAN 23 2013
SNOW HAS BEGUN TO FALL AT RST/LSE AND WILL CONTINUE THROUGH THE
REST OF THE MORNING. THE HEAVIEST BAND HAS SET UP ACROSS SOUTHEAST
MINNESOTA WHERE VISIBILITY HAS WAVERED BETWEEN 2-3SM WITH
VISIBILITY GENERALLY IN THE 3-5SM RANGE TO THE NORTHEAST OF THIS
BAND. THINK THAT RST WILL BE IFR FOR VISIBILITY FOR THE NEXT FEW
HOURS BEFORE THIS MAIN BAND SHIFTS TO THE SOUTHEAST. SNOW WILL
TAPER OFF TO FLURRIES THIS AFTERNOON WITH CLOUDS LINGERING AROUND
THE 2-3KFT RANGE. CLOUD TRENDS WILL BE TRICKY AS THE FORECAST
MODELS ARE SHOWING THIS CLOUD DECK HANGING ON AFTER THE COLD FRONT
PASSES THOUGH CURRENT OBSERVATIONS IN WESTERN MINNESOTA SHOW SKIES
CLEARING ONCE THE FRONT PASSES. WINDS WILL BE STRONG AND GUSTY FOR
A PERIOD THIS AFTERNOON AND EVENING AS WELL WITH THE COLDER AIR
DROPS IN. GUSTS IN THE 20-30KT RANGE WILL BE POSSIBLE BEFORE
TAILING OFF TONIGHT AS A RIDGE OF HIGH PRESSURE MOVES IN FROM THE WEST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
316 AM CST WED JAN 23 2013
WI...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST THURSDAY
FOR WIZ017-029-032>034.
MN...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST THURSDAY
FOR MNZ079-086>088-094-095.
IA...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST THURSDAY
FOR IAZ008-009-018-019.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...HALBACH
AREA FORECAST DISCUSSION...CORRECTED ISSUANCE TIME
NWS LA CROSSE WI
316 AM CST WED JAN 23 2013
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
316 AM CST WED JAN 23 2013
THERE ARE SEVERAL AREAS OF CONCERNS THROUGH THE SHORT TERM. FIRST
DEALS WITH LIGHT SNOW ACROSS SOUTHEAST MN...NORTHEAST IA AND FAR
SOUTHWEST WI TODAY. SECONDLY...WIND CHILLS THIS EVENING THROUGH
THURSDAY MORNING...AND FINALLY...LIKELIHOOD OF ACCUMULATING SNOW
THURSDAY NIGHT INTO FRIDAY.
WATER VAPOR RAP 500MB ANALYSIS SHOWS WELL ESTABLISHED SOUTHERN
EXTENSION OF THE POLAR VORTEX ACROSS THE AREA WITH NORTHWEST FLOW
BRINGING IN A SHORTWAVE TROUGH CURRENTLY EXTENDING FROM NORTHWEST WI
INTO NORTHWEST IA. 850-700MB WAA/ISENTROPIC LIFT PER THE RAP WAS
PRODUCING A BAND OF MOSTLY 7-10SM FLURRIES WITH POCKETS OF 4/5SM -SN
EXTENDING FROM SOUTHWEST MN INTO NORTH CENTRAL IA.
NAM SEEMS THE ODD MODEL OUT WITH THE SYSTEM COMING THROUGH THU N/FRI
WITH ITS FARTHER NORTH SOLUTION...AND PRETTY MUCH DISCOUNTED FOR
NOW. THE GFS/EC/GEM REMAIN IN PRETTY GOOD AGREEMENT AND THEREFORE
USING A CONSENSUS OF THESE MODELS.
FOR TODAY...MODELS CONTINUE TO SHOW GOOD 850-700MB WAA AND WEAK
270-280K WEAK ISENTROPIC UPGLIDE FROM SOUTHEAST MN INTO FAR
SOUTHWEST WI THROUGH THIS MORNING...SHIFTING SOUTHEAST OF THE AREA
BY AFTERNOON. BUMPED POPS INTO CATEGORICAL RANGE BASED ON THIS
FOCUSED FORCING SIGNAL SOUTH OF A LINE FROM DODGE CENTER AND
ROCHESTER MN THROUGH BOSCOBEL WI WHERE UP TO A HALF INCH OF SNOWFALL
IS POSSIBLE. FOR THIS AFTERNOON...COLD AIR ADVECTION BEHIND THE
SHORTWAVE TROUGH AND FAIRLY STEEP LOW LEVEL LAPSE RATES MAY LEAD TO
SOME FLURRY ACTIVITY ACROSS THE ENTIRE AREA. OTHERWISE...
TEMPERATURES WILL BE A BIT MILDER //RELATIVELY SPEAKING// TODAY WITH
HIGHS IN THE 10 TO 23 DEGREE RANGE. NORTHWEST WINDS WILL ALSO BE ON
THE INCREASE THIS AFTERNOON BEHIND THE WAVE.
BRISK NORTHWEST WINDS EXPECTED TO CONTINUE INTO THIS EVENING AS
TEMPERATURES START THE DOWNWARD TUMBLE INTO THE SINGLE DIGITS BELOW
ZERO RANGE ACROSS THE NORTHWEST PORTION OF THE FORECAST AREA. LOW
TEMPERATURES TONIGHT EXPECTED TO BOTTOM OUT IN THE MINUS 5 TO MINUS 10
DEGREE RANGE NORTHWEST OF A LINE FROM MEDFORD WI/BLACK RIVER
FALLS...THROUGH WINONA TO PRESTON MN AND OELWEIN IA WITH WIND CHILL
VALUES DIPPING INT THE 20-25 DEGREE RANGE. THEREFORE...WILL BE GOING
WITH A WIND CHILL ADVISORY FROM 8 PM THIS EVENING THROUGH 9 AM
THURSDAY FOR AREAS NORTHWEST OF THIS LINE.
ATTENTION THEN TURNS TO A FAIRLY VIGOROUS MID-LEVEL SHORTWAVE
TROUGH/SURFACE LOW DROPPING SOUTHEAST OUT OF ALBERTA CANADA INTO THE
DAKOTAS BY THURSDAY AFTERNOON...AND ACROSS CENTRAL WISCONSIN BY
FRIDAY MORNING. MODELS CONTINUE TO SHOWING FAIRLY STRONG N-S WING OF
850-700MB WAA/ISENTROPIC LIFT INTO THE AREA THURSDAY NIGHT AHEAD OF
THE WAVE INTO OUR AREA. THIS SIGNAL HAS BEEN INCREASING IN
CONSISTENCY FRO THE LIKELIHOOD OF SOME ACCUMULATING SNOW FOR THE
AREA. RIGHT NOW...IT APPEARS ANYWHERE FROM 1 TO 3 INCHES LOOKS
PRETTY LIKELY WITH THE HIGHER-END AMOUNTS ALONG AND NORTH OF THE
I-94 CORRIDOR. OTHERWISE...LOOKING FOR HIGHS ON THURSDAY IN THE
TEENS AND LOWS THURSDAY NIGHT IN THE SINGLE DIGITS TO TEENS ABOVE
ZERO.
SOME LINGERING DEFORMATION SNOW LOOKS LIKELY MAINLY THROUGH FRIDAY
MORNING AS THE LOW DIVES INTO LOWER MICHIGAN WITH PERHAPS AN
ADDITIONAL HALF TO ONE INCH POSSIBLE. SKIES CLEAR FRIDAY NIGHT WITH
LOWS DROPPING OFF INTO THE SINGLE DIGITS BELOW TO SINGLE DIGITS
ABOVE ZERO AS HIGH PRESSURE BUILDS IN FROM THE DAKOTAS.
.LONG TERM...SATURDAY THROUGH TUESDAY
316 AM CST WED JAN 23 2013
23.00Z GFS/ECMWF IN FAIRLY DECENT AGREEMENT THROUGH THE LONG TERM
PERIOD. HIGH PRESSURE HOLDS ACROSS THE AREA ON SATURDAY FOR MOSTLY
SUNNY SKIES WITH HIGHS EXPECTED TO TOP OFF IN THE TEENS. HIGH
PRESSURE MOVES OFF TO THE EAST SATURDAY NIGHT WITH WAA KICKING IN
AHEAD OF A MID LEVEL TROUGH EJECTING OUT OF THE INTERMOUNTAIN WEST.
THIS SPREADS CLOUD AND A SLIGHT CHANCE OF SNOW INTO THE AREA WEST OF
THE MISSISSIPPI RIVER. FOR SUNDAY THROUGH TUESDAY...LOW PRESSURE
GETS ORGANIZED ON THE LEESIDE OF THE CENTRAL ROCKIES/HIGH PLAINS.
THIS PUTS THE AREA IN BROAD AREA OF ISENTROPIC LIFT/WAA FOR A CHANCE
OF SNOW SUNDAY/SUNDAY NIGHT AND SNOW POSSIBLY MIXING WITH RAIN
MONDAY/TUESDAY DURING THE DAY AS TEMPERATURES WARM INTO THE
MIDDLE/UPPER 30S. WILL HAVE TO MONITOR THIS SYSTEM CLOSELY AS IT HAS
THE POTENTIAL OF BECOMING A FAIRLY STRONG SYSTEM WITH A GOOD AMOUNT
OF PRECIPITATION POSSIBLE.
&&
.AVIATION...
1115 PM CST TUE JAN 22 2013
CLOUDS WILL CONTINUE TO INCREASE AND LOWER OVERNIGHT...AHEAD OF
AN APPROACHING UPPER LEVEL SHORTWAVE TROUGH. EXPECT MVFR CIGS FOR
MOST OF WED MORNING. WHILE NOT OVERLY DYNAMIC...ENOUGH LIFT TO
PRODUCE AN AREA OF -SN THAT WILL IMPACT KRST. KLSE LOOKS TO BE ON
THE NORTHERN FRINGE. BUFKIT SOUNDINGS SUGGEST THE VERTICAL PROFILE
WOULD FAVOR DENDRITES...WHICH WOULD HELP LOWER VSBYS. LIGHT...FLUFFY
ACCUMS UP TO 1/2 INCH AT KRST ARE POSSIBLE. AN ASSOCIATED
SFC FRONT WILL SLIDE IN FOR MID/LATE MORNING...SWINGING WINDS TO THE
NORTHWEST. EXPECT SOME GUSTINESS POST THE FRONT...WHICH WOULD
CONTINUE INTO THE MID EVENING HOURS. SKIES SHOULD GRADUALLY CLEAR
WEST TO EAST WED EVENING.
A SFC HIGH WILL BUILD IN BY 15Z THU...WITH LIGHT WINDS AND VFR
CONDITIONS FOR THE BETTER PART OF THE DAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
316 AM CST WED JAN 23 2013
WI...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST THURSDAY
FOR WIZ017-029-032>034.
MN...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST THURSDAY
FOR MNZ079-086>088-094-095.
IA...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST THURSDAY
FOR IAZ008-009-018-019.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
330 AM CST WED JAN 23 2013
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
330 AM CST WED JAN 23 2013
THERE ARE SEVERAL AREAS OF CONCERNS THROUGH THE SHORT TERM. FIRST
DEALS WITH LIGHT SNOW ACROSS SOUTHEAST MN...NORTHEAST IA AND FAR
SOUTHWEST WI TODAY. SECONDLY...WIND CHILLS THIS EVENING THROUGH
THURSDAY MORNING...AND FINALLY...LIKELIHOOD OF ACCUMULATING SNOW
THURSDAY NIGHT INTO FRIDAY.
WATER VAPOR RAP 500MB ANALYSIS SHOWS WELL ESTABLISHED SOUTHERN
EXTENSION OF THE POLAR VORTEX ACROSS THE AREA WITH NORTHWEST FLOW
BRINGING IN A SHORTWAVE TROUGH CURRENTLY EXTENDING FROM NORTHWEST WI
INTO NORTHWEST IA. 850-700MB WAA/ISENTROPIC LIFT PER THE RAP WAS
PRODUCING A BAND OF MOSTLY 7-10SM FLURRIES WITH POCKETS OF 4/5SM -SN
EXTENDING FROM SOUTHWEST MN INTO NORTH CENTRAL IA.
NAM SEEMS THE ODD MODEL OUT WITH THE SYSTEM COMING THROUGH THU N/FRI
WITH ITS FARTHER NORTH SOLUTION...AND PRETTY MUCH DISCOUNTED FOR
NOW. THE GFS/EC/GEM REMAIN IN PRETTY GOOD AGREEMENT AND THEREFORE
USING A CONSENSUS OF THESE MODELS.
FOR TODAY...MODELS CONTINUE TO SHOW GOOD 850-700MB WAA AND WEAK
270-280K WEAK ISENTROPIC UPGLIDE FROM SOUTHEAST MN INTO FAR
SOUTHWEST WI THROUGH THIS MORNING...SHIFTING SOUTHEAST OF THE AREA
BY AFTERNOON. BUMPED POPS INTO CATEGORICAL RANGE BASED ON THIS
FOCUSED FORCING SIGNAL SOUTH OF A LINE FROM DODGE CENTER AND
ROCHESTER MN THROUGH BOSCOBEL WI WHERE UP TO A HALF INCH OF SNOWFALL
IS POSSIBLE. FOR THIS AFTERNOON...COLD AIR ADVECTION BEHIND THE
SHORTWAVE TROUGH AND FAIRLY STEEP LOW LEVEL LAPSE RATES MAY LEAD TO
SOME FLURRY ACTIVITY ACROSS THE ENTIRE AREA. OTHERWISE...
TEMPERATURES WILL BE A BIT MILDER //RELATIVELY SPEAKING// TODAY WITH
HIGHS IN THE 10 TO 23 DEGREE RANGE. NORTHWEST WINDS WILL ALSO BE ON
THE INCREASE THIS AFTERNOON BEHIND THE WAVE.
BRISK NORTHWEST WINDS EXPECTED TO CONTINUE INTO THIS EVENING AS
TEMPERATURES START THE DOWNWARD TUMBLE INTO THE SINGLE DIGITS BELOW
ZERO RANGE ACROSS THE NORTHWEST PORTION OF THE FORECAST AREA. LOW
TEMPERATURES TONIGHT EXPECTED TO BOTTOM OUT IN THE MINUS 5 TO MINUS 10
DEGREE RANGE NORTHWEST OF A LINE FROM MEDFORD WI/BLACK RIVER
FALLS...THROUGH WINONA TO PRESTON MN AND OELWEIN IA WITH WIND CHILL
VALUES DIPPING INT THE 20-25 DEGREE RANGE. THEREFORE...WILL BE GOING
WITH A WIND CHILL ADVISORY FROM 8 PM THIS EVENING THROUGH 9 AM
THURSDAY FOR AREAS NORTHWEST OF THIS LINE.
ATTENTION THEN TURNS TO A FAIRLY VIGOROUS MID-LEVEL SHORTWAVE
TROUGH/SURFACE LOW DROPPING SOUTHEAST OUT OF ALBERTA CANADA INTO THE
DAKOTAS BY THURSDAY AFTERNOON...AND ACROSS CENTRAL WISCONSIN BY
FRIDAY MORNING. MODELS CONTINUE TO SHOWING FAIRLY STRONG N-S WING OF
850-700MB WAA/ISENTROPIC LIFT INTO THE AREA THURSDAY NIGHT AHEAD OF
THE WAVE INTO OUR AREA. THIS SIGNAL HAS BEEN INCREASING IN
CONSISTENCY FRO THE LIKELIHOOD OF SOME ACCUMULATING SNOW FOR THE
AREA. RIGHT NOW...IT APPEARS ANYWHERE FROM 1 TO 3 INCHES LOOKS
PRETTY LIKELY WITH THE HIGHER-END AMOUNTS ALONG AND NORTH OF THE
I-94 CORRIDOR. OTHERWISE...LOOKING FOR HIGHS ON THURSDAY IN THE
TEENS AND LOWS THURSDAY NIGHT IN THE SINGLE DIGITS TO TEENS ABOVE
ZERO.
SOME LINGERING DEFORMATION SNOW LOOKS LIKELY MAINLY THROUGH FRIDAY
MORNING AS THE LOW DIVES INTO LOWER MICHIGAN WITH PERHAPS AN
ADDITIONAL HALF TO ONE INCH POSSIBLE. SKIES CLEAR FRIDAY NIGHT WITH
LOWS DROPPING OFF INTO THE SINGLE DIGITS BELOW TO SINGLE DIGITS
ABOVE ZERO AS HIGH PRESSURE BUILDS IN FROM THE DAKOTAS.
.LONG TERM...SATURDAY THROUGH TUESDAY
330 AM CST WED JAN 23 2013
23.00Z GFS/ECMWF IN FAIRLY DECENT AGREEMENT THROUGH THE LONG TERM
PERIOD. HIGH PRESSURE HOLDS ACROSS THE AREA ON SATURDAY FOR MOSTLY
SUNNY SKIES WITH HIGHS EXPECTED TO TOP OFF IN THE TEENS. HIGH
PRESSURE MOVES OFF TO THE EAST SATURDAY NIGHT WITH WAA KICKING IN
AHEAD OF A MID LEVEL TROUGH EJECTING OUT OF THE INTERMOUNTAIN WEST.
THIS SPREADS CLOUD AND A SLIGHT CHANCE OF SNOW INTO THE AREA WEST OF
THE MISSISSIPPI RIVER. FOR SUNDAY THROUGH TUESDAY...LOW PRESSURE
GETS ORGANIZED ON THE LEESIDE OF THE CENTRAL ROCKIES/HIGH PLAINS.
THIS PUTS THE AREA IN BROAD AREA OF ISENTROPIC LIFT/WAA FOR A CHANCE
OF SNOW SUNDAY/SUNDAY NIGHT AND SNOW POSSIBLY MIXING WITH RAIN
MONDAY/TUESDAY DURING THE DAY AS TEMPERATURES WARM INTO THE
MIDDLE/UPPER 30S. WILL HAVE TO MONITOR THIS SYSTEM CLOSELY AS IT HAS
THE POTENTIAL OF BECOMING A FAIRLY STRONG SYSTEM WITH A GOOD AMOUNT
OF PRECIPITATION POSSIBLE.
&&
.AVIATION...
1115 PM CST TUE JAN 22 2013
CLOUDS WILL CONTINUE TO INCREASE AND LOWER OVERNIGHT...AHEAD OF
AN APPROACHING UPPER LEVEL SHORTWAVE TROUGH. EXPECT MVFR CIGS FOR
MOST OF WED MORNING. WHILE NOT OVERLY DYNAMIC...ENOUGH LIFT TO
PRODUCE AN AREA OF -SN THAT WILL IMPACT KRST. KLSE LOOKS TO BE ON
THE NORTHERN FRINGE. BUFKIT SOUNDINGS SUGGEST THE VERTICAL PROFILE
WOULD FAVOR DENDRITES...WHICH WOULD HELP LOWER VSBYS. LIGHT...FLUFFY
ACCUMS UP TO 1/2 INCH AT KRST ARE POSSIBLE. AN ASSOCIATED
SFC FRONT WILL SLIDE IN FOR MID/LATE MORNING...SWINGING WINDS TO THE
NORTHWEST. EXPECT SOME GUSTINESS POST THE FRONT...WHICH WOULD
CONTINUE INTO THE MID EVENING HOURS. SKIES SHOULD GRADUALLY CLEAR
WEST TO EAST WED EVENING.
A SFC HIGH WILL BUILD IN BY 15Z THU...WITH LIGHT WINDS AND VFR
CONDITIONS FOR THE BETTER PART OF THE DAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
330 AM CST WED JAN 23 2013
WI...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST THURSDAY
FOR WIZ017-029-032>034.
MN...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST THURSDAY
FOR MNZ079-086>088-094-095.
IA...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST THURSDAY
FOR IAZ008-009-018-019.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
406 AM EST FRI JAN 25 2013
.SYNOPSIS...
HIGH PRESSURE WILL EXTEND ACROSS THE REGION TODAY. A COLD FRONT
WILL DROP THROUGH LATE FRIDAY NIGHT. HIGH PRESSURE WILL BUILD IN
SATURDAY THROUGH EARLY NEXT WEEK. A WARMING TREND IS EXPECTED NEXT
WEEK BEFORE ANOTHER COLD FRONT SWEEPS THROUGH THE SOUTHEAST
WEDNESDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
OVERVIEW: THE COLD FRONT WHICH PASSED THROUGH YESTERDAY AFTERNOON IS
LOCATED WELL TO THE SOUTH WITH MODIFIED ARCTIC AIR OOZING INTO THE
REGION. THE ARCTIC AIRMASS IS BEING MODIFIED SIGNIFICANTLY IN THE
SAVANNAH-DARIEN-LUDOWICI CORRIDOR WHERE DEWPOINTS REMAIN IN THE
LOWER 30S TO LOWER 40S WITH SURFACE TEMPERATURES STILL IN THE 40S
AS OF 25/08Z...COURTESY OF MARINE INFLUENCES VIA NORTHEAST WINDS.
EARLY MORNING SURFACE ANALYSIS SHOWS A WELL DEFINED INSITU WEDGE
IS IN PLACE ACROSS NORTH CAROLINA...SOUTH CAROLINA AND GEORGIA
WITH THE CORE OF THE WEDGE HIGH CENTERED OVER THE MID-ATLANTIC
STATES. THE WEDGE WILL EXTEND ACROSS THE CAROLINA PIEDMONT TODAY
AS THE REGION REMAINS CAUGHT IN A STIFF NORTHWEST FLOW REGIME
ALOFT. THE FORECAST CONCERNS TODAY CENTER AROUND PINNING DOWN HIGH
TEMPERATURES AND RAIN CHANCES.
RAIN CHANCES: THE 25/00Z MODELS ARE FINALLY CONVERGING ON A
MORE UNIFIED SOLUTION FOR RAIN CHANCES TODAY. ALL AGREE THAT THE
BETTER PROBABILITIES FOR MEASURABLE RAINFALL WILL BE DISPLACED
WELL TO THE NORTH AND WEST OF THE LOCAL FORECAST AREA COINCIDENT
WITH THE STRONGEST ISENTROPIC ASSENT ATOP THE INLAND WEDGE. THE
AIRMASS OVER THE WEDGE WILL SIMPLY REMAIN TOO DRY TO SUPPORT
MEASURABLE RAINFALL THIS FAR SOUTH UNTIL POSSIBLY VERY LATE IN THE
AFTERNOON WELL INLAND. THE MOST RECENT RUNS OF THE HIGHER
RESOLUTION NSSL WRF...H3R AND RAP ALSO AGREE WITH THIS SCENARIO SO
WILL LOWER POPS ACROSS THE BOARD...KEEPING A SLIGHT CHANCE FOR
SHOWERS THIS AFTERNOON FOR THE COUNTIES BORDERING THE
CSRA...SOUTHERN MIDLANDS AND THE NORTHERN SOUTH CAROLINA COAST TO
BETTER BLEND WITH THE COLLABORATED HIGHER POP FORECASTS FROM THE
COLUMBIA AND WILMINGTON WEATHER FORECAST OFFICES.
TEMPERATURES: IT WILL BE ANOTHER EXTREMELY CHALLENGING HIGH
TEMPERATURE FORECAST TODAY. MOST OF THE MODELS SHOW THE WEDGE
HOLDING FIRM FOR MUCH OF THE MORNING...BUT GRADUALLY BREAK IT DOWN
DURING THE AFTERNOON AS THE WEDGE HIGH SLOWLY SHIFTS OFF THE
NORTH CAROLINA/VIRGINA COAST. ALTHOUGH PRECIPITATION FALLING OVER
THE CENTRAL/NORTHERN MIDLANDS...THE PEE DEE AND NORTH CAROLINA
WILL LIKELY HOLD A PIECE OF THE WEDGE IN PLACE AS STRONG DIABATIC
PROCESSES TAKE HOLD...THE LACK OF A STRONG CONFLUENT FLOW OVER THE
MID-ATLANTIC SUGGESTS THE WEDGE HIGH WILL NOT BE LOCKED IN AS IS
TYPICAL IN MORE CLASSIC COLD AIR DAMMING EVENTS...HENCE THIS WEDGE
IS MORE INSITU IN NATURE. WOULD NORMALLY UTILIZE THE COLDER SIDE
OF THE GUIDANCE ENVELOP ACROSS INLAND AREAS GIVEN THE USUAL MODEL
BIASES OF BREAKING WEDGES DOWN TOO QUICKLY...BUT SINCE LITTLE IF
ANY PRECIPITATION WILL FALL ACROSS THE AREA OR THE SOUTHERN
MIDLANDS TODAY...THE QUICKER EROSION OF THE WEDGE SEEMS QUITE
PLAUSIBLE. HOWEVER...THE EXACT TIMING IS STILL UNKNOWN WHICH WILL
HAVE A MAJOR IMPACT ON HOW MUCH WARMING WILL OCCUR ACROSS FAR
INLAND AREAS. WILL ONLY NUDGE HIGHS UP A FEW DEGREES INTO THE
UPPER 40S/LOWER 50S ACROSS FAR INLAND AREAS PER COORDINATION WITH
THE PEACHTREE CITY...WILMINGTON AND COLUMBIA OFFICES...HOWEVER
WARMER TEMPERATURES WILL BE POSSIBLE IF THE WEDGE ERODES QUICKER
THAN WHAT IS EXPECTED.
THERE WILL BE A LARGE THERMAL GRADIENT ACROSS SOUTHEAST SOUTH
CAROLINA AND SOUTHEAST GEORGIA TODAY WITH HIGHS RANGING FROM THE
UPPER 40S/LOWER 50S WELL INLAND TO THE MID 60S ACROSS PARTS OF
LIBERTY...LONG AND MCINTOSH COUNTIES. MODELS SHOW SKIES BREAKING
ACROSS THE FAR SOUTH AS THE WEDGE FRONT ERODES INLAND AND THERE IS
A POTENTIAL FOR TEMPERATURES TO WARM EVEN MORE. GIVEN ALL OF THE
UNKNOWNS TODAY...FURTHER REFINEMENTS TO THE TEMPERATURE FORECAST
WILL MOST CERTAINLY BE NEEDED AS THE DAY PROGRESSES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
TONIGHT...COLD AIR DAMMING WILL BREAK DOWN QUICKLY THIS EVENING AS
THE WEDGE HIGH SHIFTS OFFSHORE AND A COLD FRONT APPROACHES FROM
THE NORTHWEST. IT LOOKS AS THOUGH THE FRONT WILL BE QUITE A BIT
SLOWER TO PASS THROUGH THE REGION TONIGHT...LIKELY NOT PUSHING
OFFSHORE UNTIL SATURDAY. UPPER LEVEL SUPPORT LOOKS MEAGER FOR
MEASURABLE RAINFALL TO OCCUR WITH THE FRONT...BUT SEVERAL MODELS
DO SPIT OUT A FEW HUNDREDTHS OF RAIN OVER SOME AREAS OVERNIGHT.
FORECAST SOUNDINGS SUGGEST THE ATMOSPHERE WILL BE MOIST ENOUGH TO
SUPPORT AT LEAST ISOLATED SHOWERS...SO WILL MAINTAIN A SLIGHT
CHANCE OF SHOWERS...MAINLY ACROSS THE WESTERN AND NORTHERN AREAS
TONIGHT. LOWS WILL RANGE FROM THE LOWER 40S INLAND TO THE LOWER-
MID 50S ALONG THE COAST.
SATURDAY...THE COLD FRONT WILL CONTINUE TO DROP THROUGH THE
FORECAST AREA SATURDAY MORNING...PROGRESSING STEADILY SOUTH OF THE
REGION BY THE AFTERNOON HOURS. FORECAST SOUNDINGS SUGGEST ANY LOW
TO MID LEVEL MOISTURE WILL QUICKLY DISSIPATE BY MID MORNING...THUS
ANY POTENTIAL FOR PRECIPITATION WITH THE DESCENDING FRONT REMAINS
QUITE LOW. HAVE THUS MAINTAINED POPS BELOW 15 PERCENT. A DECENT
HIGH TEMPERATURE GRADIENT COULD SET UP SATURDAY AFTERNOON...AS THE
NORTHERN AREAS QUICKLY FALL WITHIN COOLER NORTHERLY FLOW BEHIND
THE FRONT...WHILE SOUTHERN SECTIONS REMAIN UNDER A MORE MILD WEST
FLOW. BOTH NAM AND GFS MODEL GUIDANCE HAVE TRENDED WARMER WITH
TEMPERATURES FOR SATURDAY...AND HAVE THUS INDICATED HIGHS RANGING
FROM THE LOW 60S CHARLESTON TRI COUNTY AREA TO NEAR 70 DEGREES
ALONG THE ALTAMAHA RIVER IN FAR SOUTHEAST GEORGIA. LOW
TEMPERATURES SATURDAY NIGHT WILL BE NOTABLY COOLER HOWEVER...AS
HIGH PRESSURE BUILDING FROM THE NORTH ADVECTS A COLDER AIR MASS
ACROSS THE ENTIRE FORECAST AREA OVERNIGHT. LOW TEMPERATURES WILL
FALL INTO THE LOWER 30S NORTH/NORTHWEST TO THE UPPER 30S SOUTHEAST
GEORGIA.
SUNDAY...A HIGH PRESSURE WEDGE WILL BE ESTABLISHED ACROSS THE MID
ATLANTIC AND SOUTHEAST STATES. THIS PATTERN WILL CREATE ANOTHER
DECENT NORTHWEST TO SOUTHEAST TEMPERATURE GRADIENT...WITH COOLER
THAN NORMAL HIGHS IN THE MID 50S NORTHERN SOUTH CAROLINA COUNTIES
AND MORE SEASONAL TEMPERATURES IN THE LOWER 60S SOUTH OF THE
SAVANNAH RIVER. SOME MID TO HIGH LEVEL CLOUDS MOVING INTO THE AREA
FROM THE WEST WILL HELP MODERATE LOW TEMPERATURES SUNDAY NIGHT IN
THE UPPER 30S FAR INLAND TO THE LOWER 40S CLOSER TO THE COAST.
RIDGING AT THE SURFACE AND ALOFT...ALONG WITH LIMITED DEEP
MOISTURE...SUGGESTS DRY CONDITIONS FOR SUNDAY.
MONDAY...AS THE CENTER OF SURFACE HIGH PRESSURE SLIPS OFF THE EAST
COAST...A WELL-DEFINED COASTAL TROUGH WILL LIKELY DEVELOP OVER THE
SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA NEARSHORE WATERS.
WINDS WILL STEADILY VEER SOUTHEAST TO SOUTH AS THE DAY
PROGRESSES...AND EXPECT WARMER HIGH TEMPERATURES IN THE 60 DEGREE
RANGE AS A RESULT. WEAK CONVERGENCE ASSOCIATED WITH THE COASTAL
TROUGH COULD PRODUCE ISOLATED SHOWERS JUST OFF THE
COASTLINE...HOWEVER CONFIDENCE IN COVERAGE IS TOO LOW TO RAISE
POPS ABOVE ABOUT 12 PERCENT AT THIS TIME.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
SURFACE HIGH PRESSURE WILL SETTLE OVER THE NEARBY ATLANTIC WATERS
MONDAY NIGHT THROUGH EARLY WEDNESDAY...BEFORE A DEEP UPPER TROUGH
SWEEPS TOWARD THE AREA FROM THE NORTHERN GREAT PLAINS AND SHIFTS A
COLD FRONT INTO THE EAST COAST STATES. EXPECT A DECENT WARMING
TREND FOR TUESDAY AND WEDNESDAY...AS THE REGION REMAINS WITHIN
WARM SOUTHERLY FLOW DOWNSTREAM OF THE APPROACHING COLD FRONT.
TEMPERATURES WILL PEAK IN THE LOW TO MID 70S AWAY FROM THE
IMMEDIATE COASTLINE EACH AFTERNOON. RAIN CHANCES WILL THEN
INCREASE FROM WEST TO EAST EARLY WEDNESDAY AS THE FRONT PUSHES
INTO THE FORECAST AREA...AND HAVE INDICATED POPS IN THE 30 PERCENT
RANGE BY WEDNESDAY NIGHT WITH THE FRONT AND DEEPEST MOISTURE
DIRECTLY OVER THE SOUTHEAST STATES. NUMERICAL MODEL GUIDANCE
DIVERGES QUITE A BIT REGARDING THE PATTERN EVOLUTION AFTER THE
FRONT PUSHES OFFSHORE ON THURSDAY. AT THIS POINT...HAVE GENERALLY
LEANED TOWARD PERSISTENCE WITH A CLEANER FRONTAL PASSAGE AND
COOLER TEMPERATURES THURSDAY AND FRIDAY. HOWEVER...HAVE MAINTAINED
JUST SLIGHT RAIN CHANCES THROUGH FRIDAY TO ACCOUNT FOR MODEL
DISCREPANCIES LATE IN THE PERIOD.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
SATELLITE SHOWS LOW CLOUDS BEGINNING TO BLOSSOM ALONG THE COAST
WITH COASTAL OBSERVATIONS SHOWING MVFR CIGS. EXPECT CIGS OF 2-2.5
KFT TO MOVE INTO THE TERMINALS SHORTLY AND PERSIST FOR MUCH OF THE
MORNING HOURS...POSSIBLY DROPPING AS LOW AS 1.5 KFT. ATTM IT
APPEARS CIGS WILL REMAIN ABOVE IFR THRESHOLDS. THE WEDGE IS
EXPECTED TO BREAKDOWN LATER TODAY AS HIGH PRESSURE BEGINS TO SHIFT
OFFSHORE. THE TIMING OF THE RETURN TO VFR IS STILL UNCERTAIN...BUT
FAVOR 20Z AT KSAV AND 22Z AT KCHS. REFINEMENTS WILL BE NEEDED AS
THE DAY PROGRESSES. NO PRECIPITATION IS EXPECTED THROUGH THE
PERIOD.
EXTENDED AVIATION OUTLOOK...THERE IS A LOW CHANCE OF MVFR
CIGS/VSBYS FRIDAY NIGHT INTO EARLY SATURDAY WITH A PASSING COLD
FRONT.
&&
.MARINE...
THROUGH SUNRISE...FRISKY NORTHEAST WINDS REMAIN ACROSS THE MARINE
AREA THIS MORNING BEING SUPPORTED BY A TIGHT PRESSURE GRADIENT
BETWEEN WEAK LOW PRESSURE EAST OF CAPE CANAVERAL AND THE HIGH
PRESSURE WEDGE INLAND. WILL MAINTAIN THE SMALL CRAFT ADVISORY FOR
ALL LEGS THROUGH 8 AM.
TODAY...WINDS WILL GRADUALLY SUBSIDE OVER THE LOCAL MARINE AREA
TODAY. WINDS ARE FORECAST TO GRADUALLY VEER MORE ONSHORE AND
EVENTUALLY TO THE SOUTH AS THE INLAND WEDGE ERODES. WINDS MAY
ACTUALLY GO VARIABLE FOR A FEW HOURS ACROSS THE GEORGIA WATERS
THIS AFTERNOON AS BOTH THE NAM/RAP SHOW WEAK LOW PRESSURE OR WAVE
FORMING ALONG A SUBTLE COASTAL THROUGH OFFSHORE OF THE GEORGIA
COAST. SEAS WILL SUBSIDE TO 2-4 FT NEARSHORE WATERS AND 3-5 FT
OFFSHORE WATERS BY AFTERNOON.
TONIGHT...WINDS WILL VEER SOUTHWEST AHEAD OF A SLOW MOVING COLD
FRONT TONIGHT. LOW-LEVEL JETTING AHEAD OF THE FRONT LOOKS MEAGER
AT BEST...BUT MAY BE ENOUGH TO RAISE WINDS BACK TO 15-20 KT FOR
MOST LEGS. SEAS WILL RESPOND SLIGHTLY...BUT BOTH WINDS AND SEAS
ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS.
SATURDAY THROUGH TUESDAY...SURFACE FLOW WILL STEADILY VEER TO THE
NORTH AND BRIEFLY DIMINISH BEHIND A DESCENDING COLD FRONT
SATURDAY. SURFACE HIGH PRESSURE BUILDING FROM THE NORTH BEHIND THE
FRONT WILL THEN SUPPORT A BRIEF SURGE IN NORTHERLY FLOW ON SUNDAY
THAT COULD APPROACH MARGINAL SMALL CRAFT ADVISORY THRESHOLDS. THE
CENTER OF THE SURFACE HIGH WILL THEN SHIFT OFF THE COAST AND INTO
THE MARINE ZONES MONDAY AND TUESDAY...ALLOWING MODERATE SOUTHERLY
FLOW TO PREVAIL. CONDITIONS APPEARS TO REMAIN BELOW ADVISORY LEVELS
MONDAY AND TUESDAY.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EST THIS MORNING FOR AMZ330-
350-352-354.
SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR AMZ374.
&&
$$
ST/79
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
322 AM CST FRI JAN 25 2013
.SYNOPSIS...
06Z SFC ANALYSIS HAS A WARM FRONT RUNNING FROM THE EASTERN DAKOTAS
INTO WEST TEXAS. A WEAK LOW WAS NEAR KJLN WITH AN INVERTED TROF
RUNNING INTO SOUTHEAST NEBRASKA AND ANOTHER TROF RUNNING INTO
CENTRAL MISSOURI. DEW POINTS WERE IN THE SINGLE DIGITS AND TEENS
ACROSS MUCH OF THE MIDWEST WITH 20S AND HIGHER IN THE SOUTHERN
PLAINS AND DEEP SOUTH.
&&
.SHORT TERM...TODAY AND TONIGHT...
IMMEDIATE CONCERN IS THE SNOW POTENTIAL AND AMOUNTS.
BASED ON DATA THROUGH 07Z...THE RAP TRENDS OF 850-700MB CONDENSATION
PRESSURE DEFICITS BELOW 10...F VECTOR CONVERGENCE AND/OR 800-750MB
CONVERGENCE...AND A THETA E GRADIENT SEEMS TO CORRELATE FAIRLY WELL
WITH WHERE SNOW IS REACHING THE GROUND. USING THIS AS A ROUGH GUIDE
THERE SHOULD BE A QUICK SHOT OF LIGHT SNOW MOVE THROUGH THE
NORTHWEST QUADRANT OF THE CWFA IN THE 09-12Z TIME FRAME AND THEN THE
NORTHEAST QUADRANT IN THE 12-15Z TIME FRAME. THE FCST SOUNDINGS FROM
THE GFS LOOK OVERLY MOIST BUT THE WRF AND RAP DO HOLD ON TO A NARROW
LAYER OF DRY AIR TO AROUND SUNRISE. THIS DRY AIR WILL HELP HOLD DOWN
AMOUNTS.
AS FOR AMOUNTS...A TRACE TO A DUSTING WILL BE ABOUT ALL THAT WILL
OCCUR WITH THIS EVENT MAINLY FOR AREAS ALONG/NORTH OF I-80. THE
OVERALL CONVERGENCE WEAKENS WITH TIME AS WELL SO THE SNOW SHOULD
ONLY LAST FOR 2-3 HRS AT ANY GIVEN LOCATION.
BASED ON SATELLITE TRENDS...THERE SHOULD BE A GENERAL CLEARING OF
SKIES DURING THE LATE MORNING AND AFTERNOON HOURS. LOW LEVEL LAPSE
RATES DO GET RELATIVELY STEEP ACROSS THE FAR NORTHEAST PARTS OF THE
CWFA THAT MAY ALLOW SOME FLURRIES TO DEVELOP DURING THE AFTERNOON.
TONIGHT...ANOTHER HIGH PRESSURE BUILDS INTO THE AREA RESULTING IN
QUIET BUT DRY CONDITIONS. ..08..
.LONG TERM...SATURDAY THROUGH NEXT THURSDAY...
SATURDAY WILL BE RELATIVELY QUIET WITH WARM AIR ADVECTION GOING ON
OVERHEAD FOR GRADUALLY WARMING TEMPERATURES. HIGHS SHOULD BE IN THE
20S TO NEARLY 30.
SATURDAY NIGHT THROUGH MONDAY TO BE THE MAIN CONCERN OF THE SHIFT.
THE UPPER LEVEL PATTERN HAS SHIFTED TO A BROAD RIDGE OVER THE
MIDWEST BY SATURDAY NIGHT AND SUNDAY...WITH A SHARP UPPER LEVEL
TROUGH MOVING ONTO THE WEST COAST. A SHORTWAVE EJECTS OUT OF A MORE
SOUTHERN STREAM TROUGH...AND MOVES ACROSS THE MIDWEST THROUGH THE
WEAKENING UPPER LEVEL RIDGE AXIS. THIS PRODUCES CYCLOGENESIS OVER
NORTHEAST COLORADO ON SUNDAY. THE STRONG WARM AIR ADVECTION AHEAD
OF THIS BRINGS 850MB TEMPERATURES OVER THE FORECAST AREA ABOVE
FREEZING FOR MUCH OF SATURDAY NIGHT AND SUNDAY...JUST AS A NICE SLUG
OF MOISTURE COMES INTO THE AREA FROM THE GULF...JUST AS THE
SHORTWAVE MOVES ACROSS THE FORECAST AREA. THIS IS LIKELY TO PRODUCE
A NICE WAVE OF WARM AIR ADVECTION OVER THE AREA STARTING LATE
SATURDAY NIGHT AND CONTINUING THROUGH SUNDAY AND INTO MONDAY.
HOWEVER...THE WARM AIR ADVECTION ALOFT IS GOING TO WARM ABOVE
FREEZING BEFORE WE DO AT THE SURFACE. AN ISSUE OF LOW CONFIDENCE IN
THIS FORECAST IS HOW COLD WE WILL BE ONCE THE PRECIPITATION MOVES
INTO THE AREA...AND HOW QUICKLY TEMPERATURES WARM ON SUNDAY. THE
NAM IS OF LITTLE HELP...AS IT HAS ALREADY INITIALIZED WITH 2-4
INCHES OF SNOW COVER ON THE GROUND OVER MUCH OF IOWA...WHICH DOES
NOT EXIST. THIS IS GOING TO CONTAMINATE HOW QUICKLY IT WILL WARM
TEMPERATURES ON SUNDAY. THE GFS SHOULD HAVE A SIMILAR
INITIALIZATION. THE CANADIAN GEM IS BETTER. HOWEVER...NO MATTER
THE SOLUTION IT APPEARS THAT WE ARE LOOKING AT AT LEAST A SHORT
PERIOD OF FREEZING RAIN BEFORE TEMPERATURES WARM ABOVE FREEZING ON
SUNDAY. IT IS A VERY TOUGH FORECAST...AND HOPEFULLY MODEL CHANGES
BETWEEN NOW AND THEN WILL REMOVE THE SPECTER OF THE ICING FROM
FREEZING RAIN. SUNDAY NIGHT AND MONDAY ALL THE PRECIPITATION
GRADUALLY SHIFTS TO ALL RAIN AS TEMPERATURES CONTINUE TO WARM. THE
SURFACE TROUGH AXIS GRADUALLY SHIFTS EAST OF THE AREA AND ALLOWS
COLD AIR TO MOVE BACK INTO THE AREA BY TUESDAY...AND RAIN SHOULD
CHANGE BACK TO SNOW BEFORE THIS EVENT ENDS TUESDAY AFTERNOON AND
NIGHT.
WEDNESDAY AND THURSDAY ANOTHER COLD FRONT MOVES THROUGH THE FORECAST
AREA...AND BRINGS ANOTHER SHOT OF ARCTIC AIR INTO THE FORECAST AREA
BY THURSDAY. HIGH TEMPERATURES SHOULD BE BACK INTO THE TEENS AND
20S BY THURSDAY.
LE
&&
.AVIATION...
VFR CONDITIONS CONTINUE ACROSS THE AREA WITH SOME POCKETS OF MVFR.
HOWEVER...THE MODELS CONTINUE TO SHOW A TOP DOWN SATURATION
OCCURRING WHICH WILL ALLOW MVFR CONDITIONS OR BORDERLINE MVFR
CONDITIONS FROM 09Z/25 TO 15Z/25 DUE TO A PASSING STORM SYSTEM. THIS
STORM SYSTEM SHOULD RESULT IN -SN OCCURRING BRIEFLY AT
KCID/KDBQ/KMLI. ONCE THE STORM SYSTEM MOVES THROUGH CONDITIONS ARE
EXPECTED TO IMPROVE TO VFR BY OR AFT 18Z/25. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
LE/08
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
342 AM EST FRI JAN 25 2013
.SHORT TERM...TODAY AND TONIGHT
AN APPROACHING CLIPPER SYSTEM WILL BRING ACCUMULATING SNOW TO
SOUTHEAST MICHIGAN TODAY AND TONIGHT. THE MAIN QUESTION REMAINS HOW
MUCH SNOW WILL FALL FROM THIS SYSTEM AS IT TRACKS THROUGH THE
CENTRAL GREAT LAKES. REGIONAL 00Z RAOB SOUNDINGS FROM KDTX/KAPX/KGRB
SHOW A VERY DRY AIRMASS BETWEEN 700 AND 500 MB WHICH NEEDS TO BE
OVERCOME BEFORE SNOWFALL CAN BEGIN IN EARNEST ACROSS SOUTHEAST
MICHIGAN. THE AMOUNT OF DRY AIR IS CONCERNING WITH RELATIVE HUMIDITY
VALUES FALLING TO AROUND 10 PERCENT IN THIS LAYER. HOWEVER AS KGRB
HAS PROVED THIS LAYER CAN BE OVERCOME AS NORTHEAST WISCONSIN IS
CURRENTLY GETTING ACCUMULATING SNOWFALL. WHILE THIS DRY AIR MAY NOT
PREVENT THE INEVITABLE...IT WILL PROBABLY DELAY THE ONSET OF THE
SNOWFALL WHICH THE NAM AND HRRR MODEL DEPICT RATHER WELL THIS RUN.
WHAT THIS SYSTEM LACKS IN MOISTURE IT MAKES UP FOR IN FORCING WITH
UPPER LEVEL DIVERGENCE IN THE LEFT EXIT REGION OF A STRONG 130 KNOT
JET DIVING SOUTH OVER THE SOUTHERN GREAT LAKES AND A STRONG MID
LEVEL SHORTWAVE CLEARLY EVIDENT ON WATER VAPOR IMAGERY CURRENTLY
SITUATED OVER THE UPPER MISSISSIPPI VALLEY. WHILE THESE DYNAMICS
WILL NOT MAKE UP FOR THE LACK OF MOISTURE...THEY WILL BE ABLE TO
TAKE ADVANTAGE OF THE MEAGER MOISTURE IN PLACE WITH AN ADDED BOOST
FROM LOW WATER CONTENT SNOW AS SNOW RATIOS OF 18 TO 19 TO 1 ARE
EXPECTED. WITH DRIER MODEL SOLUTIONS YIELDING QPF IN THE 0.05 TO
0.10 RANGE SNOWFALL AMOUNTS IN THE 1 TO 2 INCH RANGE SEEM REASONABLE
FROM THIS SYSTEM DURING THE TIME OF BEST FORCING BETWEEN 12Z AND 18Z.
THE HEADLINE QUESTION NEEDS TO BE ADDRESSED GIVEN THE BULK OF THE
SNOW IS EXPECTED IN A SHORT WINDOW OF A FEW HOURS WITH COLD SURFACE
TEMPERATURES IN THE SINGLE DIGITS UP TO THE MIDDLE TEENS EXPECTED TO
RENDER REGULAR ROAD SALT VERY INEFFICIENT FOR MELTING SNOW AND ICE
DURING THE MORNING HOURS. DESPITE THESE FACTORS THE DELAYED ONSET OF
THE SNOW WILL BE HELPFUL IN LIMITING THE EFFECT OF THESE CONDITIONS
ON THE MORNING COMMUTE. IN ADDITION UPSTREAM OBSERVATIONS ACROSS
WISCONSIN ARE NOT THAT IMPRESSIVE WITH VISIBILITIES GENERALLY AT OR
ABOVE 1 MILE. WITH THIS IN MIND PLAN TO HANDLE THE SNOW WITH SPECIAL
WEATHER STATEMENTS AS IT TRACKS EAST AND FORGO HEADLINES GIVEN MOST
OF THE IMPACT WILL BE AFTER THE MORNING COMMUTE.
ALTHOUGH THE MAIN FORCING FROM THE SYSTEM WILL BE EAST DURING THE
LATE AFTERNOON HOURS THE LOW ITSELF AND COLD FRONT WILL NOT MOVE
THROUGH UNTIL THE EVENING HOURS. THIS WILL MEAN LIGHT SNOW SHOWERS
WILL CONTINUE THROUGH THE OVERNIGHT HOURS...HOWEVER WITH THE BEST
FORCING AND MOISTURE OFF TO THE EAST ONLY A DUSTING OF ADDITIONAL
ACCUMULATION IS EXPECTED AFTER 18Z.
CLOUD COVER IS EXPECTED FOR MUCH OF THE DAYTIME HOURS...LIMITING
INCOMING SOLAR RADIATION. DESPITE SOUTHERLY SURFACE WINDS AHEAD OF
THE LOW...THE AIRMASS TO THE SOUTH IS NOT MUCH WARMER THAN THE ONE
CURRENTLY IN PLACE...OFFERING LITTLE TO NO WARM AIR ADVECTION TO
BOOST SURFACE TEMPERATURES. THEREFORE HIGHS ARE EXPECTED TO BE
IN THE LOW TO MID 20S THIS AFTERNOON. CONTINUED CLOUD COVER
OVERNIGHT AND NOT MUCH COLD AIR ADVECTION BEHIND THE COLD FRONT WILL
MEAN OVERNIGHT LOWS WILL GENERALLY BE IN THE 10 TO 15 DEGREE RANGE.
&&
.LONG TERM...SATURDAY THROUGH THURSDAY
BRIEF PERIOD OF DEEPER NORTHWEST FLOW TAKES HOLD ON SATURDAY IN THE
WAKE OF THE EXITING CLIPPER SYSTEM AND ALONG THE FRONT FACE OF THE
EXPANDING LOW TO MID LEVEL ANTICYLONIC FLOW FILLING ACROSS THE UPPER
MS VALLEY. SHEAR AXIS EMBEDDED WITHIN THE WEAKENING CYCLONIC FLOW
WILL REMAIN DRAPED ACROSS THE REGION DURING THIS TIME. THIS BROAD
ASCENT WORKING INTO A DEEPENING CONVECTIVE LAYER AND A MOIST LAYER
THAT REMAINS FAVORABLY SATURATED WITH RESPECT TO ICE /-10 TO -14C
ISOTHERM/ WILL SUPPORT SOME VERY LIGHT SNOW SHOWER/FLURRY PRODUCTION
DURING THE DAY. IN ADDITION...BANDS OF LAKE DRIVEN SNOWFALL
ANCHORED ON THE LAKE HURON AGGREGATE TROUGH AXIS WILL TEND TO SHIFT
SOUTH-SOUTHEAST DOWN THE LONG FETCH IN RESPONSE TO INCREASING
PRESSURE AND A VEERING NORTHERLY WIND EMERGING ACROSS NORTHERN
PORTIONS OF THE LAKE. THE POTENTIAL DOES EXIST FOR THE WESTERN
PERIPHERY OF THIS BAND TO SWEEP ACROSS THE EASTERN THUMB SATURDAY
MORNING...BRINGING A QUICK SHOT OF ACCUMULATING SNOW. DRYING
NORTHERLY FLOW AND THE LOSS OF THE DIURNAL HEATING CYCLE WILL
SCATTER ANY LINGERING STRATOCU SATURDAY EVENING. HIGH CLOUDS WELL
IN ADVANCE OF THE NEXT SYSTEM MAY BE PROBLEMATIC FOR MAXIMIZING AN
OTHERWISE IDEAL SETUP FOR TEMPERATURES TO REALLY PLUMMET
/DIMINISHING GRADIENT...SNOW COVERAGE GROUND/. COLDEST LOCALES
CERTAINLY CAN MAKE A RUN TOWARD THE LOWER SINGLE DIGITS SUNDAY
MORNING GIVEN THE STRENGTH OF THE RESIDENT AIRMASS.
MID LEVEL CIRCULATION CURRENTLY ANCHORED OFF THE SOUTHERN CA
COASTLINE WILL RECEIVE THE NECESSARY NUDGE EASTWARD OVER THE WEEKEND
AS STRONG MID LEVEL ENERGY CRASHING INTO THE WEST COAST CARVES OUT
A DEEP LONG WAVE TROUGH. SHEARED WAVE EXPECTED TO EMBED WITHIN AN
INCREASING WEST-SOUTHWEST UPPER HEIGHT FIELD DOWNSTREAM...
TRANSLATING ACROSS SE MICHIGAN SUNDAY NIGHT. THIS PROCESS WILL
OCCUR COINCIDENT TO AND LIKELY ENHANCES A CORRIDOR OF WARM AIR
ADVECTION AND MOIST ISENTROPIC ASCENT THAT EMERGES IN INCREASING LOW
LEVEL SOUTHERLY FLOW. STRONG MODEL SUPPORT EXISTS IN DRIVING THIS
FORCING FIELD AND THE ATTENDANT MOISTURE PLUME NORTHEAST AND ACROSS
SE MICHIGAN SUNDAY NIGHT AND EARLY MONDAY. NORTHERN PORTIONS OF THE
FORECAST AREA MAY RECEIVE JUST A GLANCING SHOT OF PRECIPITATION...
WITH SOME SUGGESTION THAT THE BETTER MOISTURE TRANSPORT VECTOR
ANCHORED ON AN ATTENDANT LOW LEVEL JET CORE WILL FOCUS ACROSS THE
NORTHERN OHIO VALLEY. A WARMING THERMAL PROFILE WILL INTRODUCE
PTYPE CONCERNS DURING THE LATTER HALF OF THIS PERIOD
/MONDAY MORNING/...BUT WET BULB TEMPERATURES SECURELY BELOW FREEZING
AT ONSET WILL SUPPORT A PERIOD OF SNOWFALL OVERNIGHT. GOOD MOISTURE
QUALITY (PROGGED PW OF .75"...SPECIFIC HUMIDITY APPROACHING 3 G/KG)
INTO THE BACKGROUND FORCING INDICATES THAT THE PROGGED .2-.3" OF QPF
ACROSS THE SOUTH IS ATTAINABLE.
LOW LEVEL THERMAL RIDGE CARRYING 850 MB TEMPERATURES IN THE 6-8C
RANGE WILL SETTLE OVERHEAD IN THE WAKE OF THE EARLY DAY WARM FRONTAL
PASSAGE ON MONDAY. MID LEVEL MOISTURE STRIPS EAST BUT PLENTIFUL LOW
LEVEL MOISTURE AIDED BY THE SNOWMELT MAY PROMOTE A PERIOD OF
FOG/DRIZZLE. THIS WILL WARRANT JUST A CONSERVATIVE ADJUSTMENT
UPWARD IN HIGHS MONDAY DESPITE THE STRENGTHENING SOUTHWEST
GRADIENT/ADVECTIVE PROCESS. HIGHS INCHING TOWARD THE LOWER 40S
SOUTH. MODEL CONSENSUS PROVIDING A MORE PROGRESSIVE OUTLOOK WITH
THE EASTWARD TRANSLATION OF THE MEAN WESTERN CONUS TROUGH EARLY NEXT
WEEK...PERHAPS OWING TO THE PRESENCE OF A CONSIDERABLY FLATTER/LESS
AMPLIFIED FLOW DOWNSTREAM. THIS TRANSLATES INTO A FASTER ATTENDANT
LEAD FRONTAL PASSAGE SOMETIME ON TUESDAY...PROVIDING SOME DOUBT AS
TO THE DEGREE OF THE PRE-FRONTAL WARMUP. THIS FIRST ROUND OF COLD
AIR ADVECTION NOTHING EXTRAORDINARY...LIKELY SIMPLY EASING
TEMPERATURES BACK TO LATE JANUARY STANDARDS. THE NEXT ARCTIC PUSH
WILL BE TIED TO THE MORE PRONOUNCED TRAILING HEIGHT FALL REGION
PIVOTING THROUGH THE MEAN TROUGH...ARRIVING FOR THE END OF NEXT
WEEK.
&&
.MARINE...
AN ALBERTA CLIPPER SYSTEM WILL TRACK THROUGH THE GREAT LAKES REGION
TODAY AND TONIGHT. LIGHT SOUTHERLY WINDS TODAY WILL KEEP WAVE
HEIGHTS LOW THROUGH THE DAY. WINDS BEGIN TO INCREASE WITH GUSTS IN
THE 15 TO 20 KNOT RANGE AND EVENTUALLY SHIFTING TO THE
WEST-NORTHWEST ON SATURDAY BEHIND THE DEPARTING LOW. AT THIS TIME
NOT EXPECTING WAVES TO REACH SMALL CRAFT ADVISORY CRITERIA DURING
THE SATURDAY TIMEFRAME. WINDS EASE CONSIDERABLY SATURDAY NIGHT AS
HIGH PRESSURE TRACKS THROUGH THE REGION BEFORE PICKING UP SLIGHTLY
AND TURNING SOUTHERLY ON SUNDAY AS THE HIGH MOVES OFF TO THE EAST.
&&
.AVIATION...ISSUED 1216 AM EST FRI JAN 25 2013
//DISCUSSION...
AN APPROACHING CLIPPER SYSTEM WILL BRING LIGHT SNOW TO THE TAF SITES
LATER THIS MORNING AS IT TRACKS THROUGH THE CENTRAL GREAT LAKES
REGION. REGIONAL 00Z RAOB SOUNDINGS SHOW QUITE A BIT OF DRY AIR
NEEDS TO BE OVERCOME BEFORE SNOW CAN START...WITH THE RECENT NAM RUN
DEPICTING THIS LATER START AND LOWER SNOWFALL AMOUNTS QUITE WELL.
WILL DELAY THE ONSET OF SNOWFALL AT THE TAF SITES THIS MORNING WITH
SNOW EXPECTED TO START AT MBS AROUND 10Z AND THE METRO AIRPORTS
AROUND 12-13Z. THIS EVENT IS EXPECTED TO BRING WIDESPREAD MVFR
CONDITIONS AND OCCASIONAL IFR VSBYS IN THE HEAVIER SNOW BANDS. MVFR
CONDITIONS WILL LINGER THIS AFTERNOON AND INTO THE EVENING AS LIGHT
SNOW SHOWERS CONTINUE ACROSS SOUTHEAST MICHIGAN. SNOWFALL AMOUNTS IN
THE 1 TO 2 INCH RANGE ARE EXPECTED FROM THIS SYSTEM.
FOR DTW...CEILINGS AND VISIBILITIES WILL DIMINISH QUICKLY AFTER THE
SNOW BEGINS AFTER 12Z. SNOW WILL START OUT LIGHT AND GRADUALLY
INTENSIFY AFTER 16Z. LIGHT SNOW WILL CONTINUE THROUGH THE AFTERNOON
AND EVENING HOURS.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE THAT PRECIPITATION TYPE WILL REMAIN ALL SNOW
DURING THE TAF PERIOD.
* HIGH CONFIDENCE FOR CEILINGS TO DROP BELOW 5000 FEET AFTER 12Z
THIS MORNING.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...KURIMSKI
LONG TERM....MR
MARINE.......KURIMSKI
AVIATION.....KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS
ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1150 PM CST THU JAN 24 2013
.UPDATE...
/ISSUED 818 PM CST THU JAN 24 2013/
QUICK UPDATE ON THE SNOWFALL POTENTIAL FOR TONIGHT...OR TO SAY IT
BETTER...THE LACK THERE OF. LOW LEVEL DRY AIR HAS BEEN A
SIGNIFICANT ISSUE TONIGHT...WITH SNOW STRUGGLING TO MAKE IT TO THE
GROUND. LOOKING AT FORECAST SOUNDINGS FROM THE RAP...ABOUT THE
TIME THE LOW LEVELS SATURATE...THE MID LEVELS DRY OUT AS A RATHER
PRONOUNCED DRY SLOT ON WATER VAPOR FROM THE DAKOTAS INTO NRN MN
MOVES OVERHEAD. ALL OF THIS IS REALLY WORKING HARD AGAINST
OUR SNOW TONIGHT...AND CONFIDENCE IN SNOW FALLING ANYWHERE WITHIN
THE MN PORTION OF THE CWA IS PLUMMETING. IN FACT...BASED ON
CURRENT RAP...25.00 NAM ROLLING IN...AND HOPKINS WRF MEMBERS...MAY
BE JUST A STRUGGLE TO GET AN INCH OF SNOW ACROSS OUR ADVY COUNTIES
IN WI AS ALL OF THESE MODELS KEEP THE SNOW NORTH AND EAST OF THE
MPX CWA. WILL NOT CHANGE THE ADVY AT THIS POINT...THOUGH WILL
PROBABLY BE TRENDING POPS AND SNOWFALL AMOUNTS DOWNWARD SHORTLY.
&&
.AVIATION.../06Z TAF ISSUANCE/
DRY AIR IS BEATING OUT THE SNOWFALL...AND CONFIDENCE IN IT
OCCURRING AT ANY OF THE TERMINALS IS CLOSE TO NIL. PROBLEM HAS BEEN
A DISCONNECT BETWEEN MID/UPPER LEVEL MOISTURE AND LOW LEVEL
MOISTURE. NAMELY...AS THE LATER FINALLY SHOWS UP...THE FORMER
DEPARTS AS A DRY SLOT MOVES OVERHEAD. BEST CHANCE FOR SNOW WHEN
LOOKING AT THE RAP WOULD BE EAU...BUT EVEN HERE ONLY EXPECT A
DUSTING...WITH MVFR VIS RESTRICTIONS AT WORST. FOR CIGS...MVFR
CIGS HAVE BEEN CONFINED CLOSER TO THE SFC LOW...WHICH AT 6Z WAS
OVER NE NODAK AND WILL BE OVER NRN WI BY 15Z. LOW CIGS SHOULD BE
CONFINED CLOSER TO THE LOW AND WILL LIKELY PUT NRN TERMINALS ON
SRN EDGE OF MVFR CIGS DURING THE DAY FRIDAY. CLEARING MOVING IN
QUICKLY ACROSS NORTH CENTRAL NODAK ALSO LEADING TO LESS CONFIDENCE
ON WHAT WILL HAPPEN WITH CIGS TOMORROW. WHERE THERE STILL IS HIGH
CONFIDENCE IS WITH GUSTY NW WINDS FRIDAY. CAA DURING THE
AFTERNOON WILL PROMOTE STEEP LAPSE RATES AND EFFICIENT MIXING OF
WINDS DOWN FROM 3K FT...WHICH SHOULD PROMOTE NW GUSTS TO 35 KTS IN
WRN MN DURING THE LATE MORNING AND TO 30 KTS ACROSS ERN MN AND WRN
WI IN THE EARLY AFTERNOON. AFTER 00Z...SKIES WILL BE QUICKLY
CLEARING OUT AND WINDS CALMING DOWN.
KMSP...HAVE REMOVED SNOW MENTION FROM THE TAF...THOUGH A FEW
FLURRIES CAN NOT BE RULED OUT THROUGH 8Z...BUT DO NOT ANTICIPATE
AND VIS RESTRICTIONS. CIGS DO NOT LOOK TO LOWER TO MVFR LEVELS
UNTIL AROUND 12Z AS CIGS CURRENTLY UP BY FARGO MOVE INTO THE TWIN
CITIES. LOTS OF UNCERTAINTY WITH HOW LONG RESTRICTED CIGS WILL
HANG AROUND...BUT ENHANCED MIXING WITH BARE GROUND MAY SUPPORT A
MORE ROBUST POST FRONTAL STRATO CU FIELD THAN AREAS TO THE
N/W...KEEPING MVFR CIGS IN PLACE THROUGH THE AFTERNOON. WITH
WINDS...TRANSITION TO THE NW WILL HAPPEN DURING THE MORNING
RUSH...MAKING THE TRANSITION OF AIRPORT OPERATIONS FROM THE 15S
TO THE 30S TRICKY. SEEING PLENTY OF GUST POTENTIAL FOR TOMORROW
AND MAY SEE A GUST OR TWO APPROACH 35 KTS AROUND 18Z AS INITIAL
SURGE OF COLD AIR MOVES IN.
/OUTLOOK FOR KMSP/
SAT...VFR. SE WINDS AT 5-10 KTS.
SUN...MVFR WITH IFR AND -SN/FZRA/RA POSSIBLE. WINDS SE 10 KTS.
MON...MVFR/IFR CIGS POSSIBLE. WINDS SE 4-8 KTS.
&&
.PREV DISCUSSION...
/ISSUED 540 PM CST THU JAN 24 2013/
A WEAK CLIPPER SYSTEM WILL MOVE THROUGH TONIGHT AND THE NEXT COUPLE
OF DAYS WILL CONTINUE TO BE COLD. A BRIEF WARM UP EXPECTED THIS
WEEKEND WITH A SECOND CHANCE FOR PRECIPITATION. THIS WILL BE
FOLLOWED BY A THIRD STORM SYSTEM EARLY NEXT WEEK...AND ANOTHER SURGE
OF ARCTIC AIR FOR THE END OF THE PERIOD.
TONIGHT AND FRIDAY...EARLY AFTERNOON WATER VAPOR IMAGERY TOGETHER
WITH 500MB HEIGHTS AND WINDS IDENTIFIED A SHORTWAVE TROUGH ALONG THE
MONTANA/CANADA BORDER...WITH ANOTHER CUT OFF LOW OFF THE CALIFORNIA
COAST...AND BROAD ALEUTIAN LOW IN THE GULF OF ALASKA. THE PV ANOMALY
ASSOCIATED WITH THE FIRST FEATURE WILL MOVE NORTH OF THE
REGION...WITH QVECT CONVERGENCE AND HEIGHT FALLS PROVIDING
WIDESPREAD FORCING FOR UPPER LEVEL ASCENT. THE FRONTOGENETIC
SIGNATURE IS RATHER BENIGN...SO NOT EXPECTING ANY AREAS OF MODERATE
OR HEAVY SNOW TO DEVELOP. HOWEVER...FORECAST SOUNDINGS SHOW
SATURATION FROM 03-09Z TONIGHT...SO SHOULD SEE AT LEAST SOME LIGHT
SNOW DURING THIS TIME PERIOD. HIRES MODELS SEEM TO HAVE A GOOD
HANDLE ON THE FAST MOVING AREA OF LIGHT PRECIP...AND WITH SNOW
RATIOS OF 20-25:1 EXPECTING AS MUCH AS 2 TO 4 INCHES IN WESTERN
WISCONSIN NEAR EAU CLAIRE/LADYSMITH AREA. LIGHT SNOW WILL LIKELY LINGER
ACROSS WEST CENTRAL WI COUNTIES ON FRIDAY MORNING ON THE WESTERN
PERIPHERY OF THE TROUGH AS IT MOVES ACROSS THE GREAT LAKES.
COLD AIR ADVECTION WILL FOLLOW IN THE WAKE OF THIS SYSTEM AND
KEEP THE BOUNDARY LAYER WELL MIXED...WITH SUSTAINED NORTHWEST
WINDS OF 20 MPH...AND GUSTS NEAR 30 MPH BEGINNING LATE MORNING AND
LASTING THROUGH FRIDAY AFTERNOON. THIS COULD CAUSE SOME BLOWING
DRIFTING OF ANY SNOW THAT HAS FALLEN. THE DIURNAL TEMP TREND WILL
BE A BIT ABNORMAL ON FRIDAY DUE TO THE MORNING FRONTAL PASSAGE.
WILL LIKELY SEE FALLING TEMPS IN THE MORNING...FOLLOWED BY NEARLY
STEADY TO ONLY SLIGHTLY WARMING READINGS IN THE AFTERNOON.
SURFACE HIGH PRESSURE SETS IN FRIDAY EVENING...WITH ATTENDANT
CLEAR SKIES AND LIGHT WINDS FOSTERING ANOTHER COLD NIGHT.
ANTICIPATE LOWS TO DIP TO NEAR 15 BELOW /NORTHWEST NEAR KAXN/ TO 5
BELOW /SOUTHEAST NEAR KMSP AND KEAU/. WIND CHILL VALUES ARE NOT
ANTICIPATED TO QUITE REACH ADVISORY CRITERIA DUE TO THE EXPECTED LIGHT
WIND SPEEDS.
OVER THE UPCOMING WEEKEND...THE LARGE SCALE FLOW PATTERN EVOLVES
TO MORE OF A WEST/SOUTHWEST DIRECTIONAL COMPONENT. THIS SHOULD
YIELD TEMPERATURE MODERATION INTO THE 15 TO 20 DEGREE RANGE FOR
HIGHS SATURDAY...WITH LITTLE IN THE WAY OF A DROP OFF ON SATURDAY
NIGHT...WHEN LOWS ARE GENERALLY EXPECTED TO RANGE BETWEEN 10 AND
15 DEGREES ABOVE ZERO. ALTHOUGH A FAIR AMOUNT OF CLOUDS WILL STREAM
NORTH INTO THE AREA ON SUNDAY...SHOULD STILL BE ABLE TO WARM INTO THE
25 TO 35 DEGREE RANGE. HOWEVER...THE INFILTRATION OF WARMER AIR
WILL LIKELY BE ACCOMPANIED BY A THREAT FOR OCCASIONAL FREEZING
PRECIPITATION FROM SUNDAY NIGHT INTO TUESDAY...AS A SURFACE
TROUGH NOSES INTO THE UPPER MIDWEST. THIS THREAT APPEARS THE
GREATEST FROM SOUTHERN/EASTERN MN INTO WEST CENTRAL WI...AS
SUPPORTED BY THE SREF PROBABILITY OF FREEZING RAIN PROGS.
FORECAST CONFIDENCE REGARDING A POTENTIAL SYSTEM FOR EARLY NEXT
WEEK IS NOT AS HIGH AS WAS HOPED FOR...AFTER INSPECTION OF THE 12Z
ECMWF...WHICH ESSENTIALLY ERASED ITS DEPICTION OF A SUB-1000 MB
SURFACE LOW JUST PASSING JUST SOUTHEAST OF THE FORECAST AREA ON
TUESDAY. THE 12Z GEM AND GFS SOLUTIONS...ALTHOUGH DIFFERING A BIT
IN THE PATH...ALSO FEATURED A DECENT /SNOW-MAKER/ SYSTEM AFFECTING
THE FORECAST AREA ON TUESDAY. DUE TO THE INCONSISTENCY IN THE
MODELS...DID NOT GO WITH LIKELY POPS AT THIS POINT...BUT DID
INCLUDE HIGH CHANCE POPS FOR PRECIPITATION ON MONDAY NIGHT AND
TUESDAY. PRECIP TYPE ALSO LOOKS TO BE POTENTIALLY
MIXED/FREEZING...BUT THAT WILL DEPEND ON HOW THE SYNOPTICS
EVOLVE.
IN THE WAKE OF THE POTENTIAL SYSTEM...COLD AIR WILL AGAIN
INFILTRATE THE REGION...WITH HIGHS AROUND 15 TO 20 DEGREES BELOW
CLIMATOLOGICAL NORMALS FOR WEDNESDAY AND THURSDAY.
FURTHERMORE...LOW TEMPERATURES WILL LIKELY DROP TO BETWEEN ZERO
AND 15 BELOW FOR WEDNESDAY AND THURSDAY NIGHTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...WINTER WEATHER ADVISORY UNTIL NOON CST FRIDAY FOR BARRON-
CHIPPEWA-RUSK.
&&
$$
LS/MPG
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1204 AM CST FRI JAN 25 2013
.SHORT TERM...
ISSUED AT 334 PM CST THU JAN 24 2013
(TONIGHT)
THE MAIN ISSUE FOR TONIGHT IS WHETHER OR NOT WE WILL SEE SOME LIGHT
WINTRY PRECIPITATION. THE OVERALL SYNOPTIC SCENARIO APPEARS
UNCHANGED. AN EXPANSIVE COLD HIGH PRESSURE SYSTEM CURRENTLY CENTERED
THRU THE WRN GREAT LAKES WILL RETREAT EASTWARD THRU THE OH VALLEY
AND INTO THE EASTERN U.S. BY DAYBREAK FRIDAY. IN THE PROCESS...LOW
LEVEL FLOW WILL VEER TO MORE SELY TONIGHT AND A BROAD LOW LEVEL WAA
REGIME WILL DEVELOP. CONCURRENTLY A VERY WEAK IMPULSE WILL TRACK
THRU THE MID MS VALLEY WITHIN THE NW FLOW ALOFT. BOTH OF THESE
FEATURES WILL PRODUCE SOME WEAK ASCENT WITH THE LOW LEVEL WAA MORE
FOCUSED ACROSS SRN MO AND SRN IL WHILE THE MAIN ASCENT WITH THE
UPPER DISTURBANCE WILL BE FOCUSED NORTH OF THE CWA. MOISTURE IS ALSO
AN ISSUE WITH HIGH LEVEL MOISTURE WITHIN THE NW FLOW ALOFT STREAMING
ACROSS THE AREA WHILE THE SWLY LLJ TRANSPORTS MODEST LOW LEVEL
MOISTURE FROM THE SRN PLAINS AND LOWER MS VALLEY. THE RESULTANT
MOISTURE STRATIFICATION IS HIGH AND LOW WITH MOST OF THE LIFT
INDICATED TO BE IN BETWEEN THE TWO MOISTURE SOURCES WHERE THE AIR
MASS IS DRY. NORMALLY THIS MIGHT SUGGEST DRIZZLY PCPN BUT THE LOW
LEVELS WONT BE THAT DRAMATICALLY MOIST - I.E. IFR AND LOWER CIGS.
THIS IS IN PART DUE TO THE DRY BOUNDARY LAYER CURRENTLY OVER THE
AREA. THE GFS SEEMS TO RECOGNIZE THIS AS DOES THE HRRR AND
RUC...WHICH HAVE NO QPF OR A COUPLE OF SPITS. ALTERNATIVELY THE NAM
AND LOCAL WRF SUGGEST VERY LIGHT QPF OVER THE ENTIRE CWA...HOWEVER
THEY ARE ALREADY IN ERROR AS THERE SHOULD BE PCPN ACROSS OK AND AR.
ADDING TO THE QUANDARY IS THE THERMAL PROFILES WHICH SUGGEST SLEET OR
FREEZING RAIN ACROSS SE MO AND MAINLY SNOW OR SLEET CENTERED ALONG
I-70 AND SNOW FURTHER NORTH. THE BOTTOM LINE IS THAT I THINK DRIZZLE
IS LESS LIKELY AND ANY PCPN THAT OCCURS WILL BE EITHER BE VERY LIGHT
OR SHOWERY IN NATURE...WITH THE GREATEST PROBABILITY ACROSS SE MO
AFTER 06Z. WHATEVER DOES FALL AND ACCUMULATE WILL BE VERY LIGHT.
GIVEN THE UNCERTAINTIES I HAVE KEPT WITH THE CHANCE POPS FROM THE
PREVIOUS FORECAST AND DONT HAVE ANY HEADLINES. THAT SAID...SOME ZL--
OR ZR-- COULD PRODUCE A VERY LIGHT GLAZE ON ANY UNTREATED SURFACES.
I WILL ISSUE AN SPS TO HIGHLIGHT THIS POTENTIAL.
GLASS
&&
.LONG TERM...
ISSUED AT 334 PM CST THU JAN 24 2013
(FRIDAY - SUNDAY)
LIGHT PRECIPITATION SHOULD BE ON THE WAY OUT EARLY TOMORROW MORNING AS
BY 1200 UTC NAM 290-305K ISENTROPIC SURFACES DEPICT SUBSIDENCE WEST OF THE
MISSISSIPPI RIVER WHICH SPREADS EAST WITH TIME. LEFT SCHC POPS FOR THE
EASTERN THIRD OF THE CWA WHERE WEAK MOIST/WARM ADVECTION CONTINUES
UNTIL ROUGHLY 1500 UTC. SKIES SHOULD QUICKLY CLEAR OUT TOMORROW WITH
SUBSIDENCE IN THE WAKE OF SHORTWAVE TROUGH PASSING THROUGH THE GREAT
LAKES REGION. AT THE SFC...A WEAK COLD FRONT/WIND SHIFT WILL COME THROUGH
ATTENDANT TO A SFC CYCLONE ASSOCIATED WITH THE NORTHERN STREAM CLIPPER.
WITH CLEARING SKIES AND A WESTERLY COMPONENT TO THE WIND...WENT ABOVE
WARMEST GUIDANCE YIELDING HIGHS FROM UPPER 30S IN THE NORTH TO NEAR 50
OVER PORTIONS OF SOUTHEAST MISSOURI.
ANOTHER SHOT OF COLD CANADIAN AIR IS IN STORE FOR FRIDAY NIGHT AND SATURDAY
WITH A 1030+ HPA SFC HIGH SLIDING SE INTO THE MID-MISSOURI RIVER VALLEY
BY 0600 UTC SATURDAY. EXPECT LOWS IN THE TEENS AND TWENTIES WITH CLEAR
SKIES AND LOW DEWPOINTS. WINDS SHOULD STAY UP JUST ENOUGH MOST LIKELY TO
PREVENT DECOUPLING AND TEMPERATURES BOTTOMING OUT SEVERAL DEGREES COOLER.
FOR HIGHS ON SATURDAY...COOLEST READINGS WILL BE IN THE M/U 20S OVER
WEST-CENTRAL ILLINOIS AND MID 30S OVER CENTRAL MISSOURI. THESE READINGS
ARE CLOSER TO COOLER MET GUIDANCE GIVEN WEAK CAA AND INCREASING CIRRUS
THROUGHOUT THE DAY.
CLOUDS SHOULD CONTINUE TO BE ON THE INCREASE AND GRADUALLY LOWER THROUGH
SATURDAY NIGHT AS A SHORTWAVE TROUGH EJECTS OUT OF THE DESERT SOUTHWEST.
THE COMBINATION OF STRONG MOIST/WARM ADVECTION AROUND THE WESTERN
PERIPHERY OF A LOW-LEVEL ANTICYCLONE OVER THE GULF COAST AND DCPVA AHEAD
OF THE TROUGH AXIS SHOULD PROVIDE PLENTY OF SUPPORT FOR GOING POPS. WITH
COLD AIR STILL IN PLACE BEHIND DEPARTING CANADIAN AIRMASS AND COLD GROUND
TEMPERATURES FROM PREVIOUS SPELLS OF ARCTIC AIR...POTENTIAL FOR ACCUMULATING
FREEZING RAIN APPEARS LIKELY FOR PORTIONS OF THE AREA. CURRENT EXPECTATION
IS FOR FREEZING RAIN TO BEGIN LATE SATURDAY NIGHT OVER CENTRAL MISSOURI
AND SPREADING E/NE WITH TIME. ONSET OF PRECIPITATION WILL LIKELY BE A
COMBINATION OF SLEET/SNOW DUE TO VERY DRY AMS BELOW 700 HPA LEADING TO
STRONG EVAPORATIONAL COOLING/WET BULBING. HOWEVER...WAA WILL WIN OUT FAIRLY
QUICKLY (WITHIN AN HOUR OR TWO) AND CHANGE PTYPE OVER TO FREEZING RAIN AND
EVENTUALLY RAIN AS SFC TEMPS WARM ABOVE FREEZING. EXCEPTION WOULD BE OVER
NORTHERN SECTIONS OF THE AREA INCLUDING QUINCY WHERE SLEET/SNOW MIX MAY
CONTINUE FOR A FEW HOURS BEFORE CHANGING OVER TO FREEZING RAIN. IN THIS
AREA...HAVE HALF AN INCH OF SNOW OR LESS TO ACCOUNT FOR THIS SCENARIO.
GENERALLY...EXPECTING A 6-HR PERIOD OR SO OF FROZEN PRECIPITATION WITH
FREEZING RAIN BEING THE PRIMARY PTYPE BEFORE THE CHANGEOVER TO
PLAIN OLD RAIN FOR MOST LOCATIONS. AMOUNTS OF FREEZING RAIN IN THE
CURRENT FORECAST ARE ON THE ORDER OF A TENTH OF AN INCH OR
LESS...BUT CERTAINLY ENOUGH TO CREATE TRAVEL PROBLEMS FOR THOSE
VENTURING OUT SUNDAY MORNING. TEMPERATURES BEHIND THE WARM FRONT
WILL CONTINUE TO RISE THROUGH THE OVERNIGHT HOURS SO WENT WITH A
NON-DIURNAL TEMPERATURE TREND FOR SUNDAY NIGHT.
(MONDAY - THURSDAY)
VERY WARM AIR IS IN STORE FOR MONDAY-TUESDAY WITH HIGHS IN THE 50S AND 60S
EACH DAY. MAIN CONCERN WITH REACHING THESE TEMPERATURES IS OBVIOUSLY
CLOUDS/PRECIP CHANCES. MODELS CONTINUE TO PRINT OUT LIGHT QPF EACH DAY...
BUT FORCING SEEMS INNOCUOUS AND BELIEVE MODELS ARE DOING THIS DUE TO THE
VERY STRONG AND ANOMALOUS LOW-LEVEL MOISTURE RETURN. WARMEST DAY SHOULD
BE TUESDAY AHEAD OF FRONT AS NWP GUIDANCE HAS 850-HPA TEMPS AOA +8C.
DEEP MIXING FOR THE TIME OF YEAR TO NEAR 850 HPA AND COMPRESSIONAL WARMING
AHEAD OF FRONT ALL SUGGEST HIGHS NEAR RECORD OR RECORD-BREAKING. THEREFORE...
HAVE OPTED TO INCLUDE RECORD HIGHS AND RECORD HIGH MINIMUMS FOR MONDAY AND
TUESDAY IN THE CLIMO SECTION BELOW. HIGH TEMPERATURES...ESPECIALLY FOR
TUESDAY...WOULD LIKELY BE SEVERAL DEGREES TOO COOL IF THERE ARE BREAKS IN
THE CLOUDS. FOR EARLY WEEK...WENT AT LEAST A FEW DEGREES ABOVE CR
INITIALIZATION DUE TO REASONING MENTIONED ABOVE.
COLD FRONT SHOULD MOVE THROUGH ON THE DAY TUESDAY WITH SHOWERS AND
THUNDERSTORMS STILL A GOOD BET ALONG AND AHEAD OF THE BOUNDARY. ALSO POTENTIAL
FOR SEVERE WEATHER GIVEN STRONG DYNAMICS PROGGED AND INSTABILITY PARAMETERS.
SFC DEWPOINTS MAY EVEN APPROACH 60 DEGREES...WHICH FOR THIS TIME OF YEAR IS
CERTAINLY A RED FLAG FOR POTENTIAL STRONG TO SEVERE STORMS. HOWEVER...THERE
IS STILL QUITE A BIT OF UNCERTAINTY IN REGARDS TO EXACT TRACK OF SFC LOW
AND AMOUNT OF INSTABILITY AHEAD OF BOUNDARY. NEW ECMWF WHICH CUTS OFF
SHORTWAVE TROUGH OFF THE COAST OF CALIFORNIA WITH A NORTHERN STREAM SHORTWAVE
TRAVERSING THE NORTHERN PLAINS IS AN OUTLIER AND WAS DISCOUNTED FOR NOW.
THIS SCENARIO WOULD HAVE A WEAKER FROPA EARLIER ON TUESDAY WITH LESS
DYNAMICS FOR SEVERE WEATHER.
BEHIND THE COLD FRONT...WEDNESDAY AND THURSDAY LOOK MUCH COOLER...I.E....
TOWARD SEASONAL NORMS WITH HIGHS IN THE 30S AND 40S. THIS TIME PERIOD
ALSO WILL LIKELY BE DRY...THOUGH SOME MODELS HAVE HINTED AT THE POSSIBILITY
OF SOME ENERGY LAGGING BEHIND IN THE FOUR-CORNERS REGION WHICH COULD YIELD
POTENTIALLY WINTRY WEATHER SOMETIME LATER NEXT WEEK.
GOSSELIN
&&
.AVIATION...
ISSUED AT 1129 PM CST THU JAN 24 2013
MAIN FCST CHALLENGE CONTINUES TO BE THE DVLPMNT OF WINTRY PRECIP
TOWARDS MRNG. THE STRONG AREA OF HIGH PRESSURE THAT PUSHED A
STRONG COLD FRONT THRU YESTERDAY HAS MOVED TO THE EAST COAST
ALLOWING WINDS TO TURN ESE/SE THIS EVENING. THE COLD FRONT
CURRENTLY STRETCHES FROM NTHRN TX ALONG THE AR/LA BORDER ACROSS
CNTRL MS AND ON INTO THE TN VLY. A WEAK AREA OF LOW PRESSURE IS
FCST TO MOVE ALONG THE FRONT THRU TOMORROW AND SHOULD BE LOCATED
IN THE UPPER OH RIVER VLY BY TOMORROW EVENING. THE SRLY FLOW ON
THE BACKSIDE OF THE HIGH AND THE CIRCULATION IN ASSOC WITH THE LOW
PRESSURE WILL ALLOW WARM AND MORE MOIST AIR TO SURGE NORTH OVER
TOP THE COLD AIR AT THE SFC. THERE IS MOISTURE AND CLOUDS AOA 15
KFT AND MOISTURE AND CLOUDS AOB 8KFT. THE QUESTION IS IF THERE IS
ENOUGH LIFT WHERE THE MOISTURE IS TO PRODUCE PRECIP. MODELS
CONTINUE TO INDICATE TOO MUCH PRECIP...THOUGH THEY HAVE TRENDED
DRIER THIS EVENING. IF ANYTHING DOES DVLP...IT SHOULD BE LIGHT AND
SHORT LIVED. IF IT DVLPS...IT SHOULD BE ALL SNOW AT KUIN BUT A MIX OF
FREEZING RAIN/DRIZZLE AND/OR SLEET IN THE STL METRO. PRECIP SHOULD
BE EAST OF KCOU IF IT DVLPS. NOT CONFIDENT ENOUGH TO INCLUDE ANY
PRECIP ATTM SO CONVERTED THE PROB30 TO VCSH TO INDICATE THE
UNCERTAINTY. A COLD FRONT PUSHES THRU TOMORROW MORNING ENDING THE
PRECIP THREAT AND CLOUDS WILL CLEAR FROM W-E AFTER FROPA.
SPECIFICS FOR KSTL...
LIGHT WINTRY MIX POSSIBLE TOWARDS SUNRISE. SHOULD BE VERY LIGHT
AND BRIEF. NOT CONFIDENT ENOUGH IN THE DVLPMNT OF THE PRECIP TO
INCLUDE ATTM...CONVERTED THE PROB30 GROUP TO VCSH TO TRY AND
CONVEY THE UNCERTAINTY. WINDS GO WESTERLY TOMORROW MORNING AFTER
A COLD FRONT AND SKIES SHOULD CLEAR BY NOON.
2%
&&
.CLIMATE...
ISSUED AT 334 PM CST THU JAN 24 2013
RECORD OR NEAR RECORD-BREAKING TEMPERATURES ARE EXPECTED ON MONDAY
AND TUESDAY. BELOW IS A TABLE OF RECORD HIGHS AND RECORD HIGH
MINIMUMS FOR ARE THREE OFFICIAL CLIMATE STATIONS: ST. LOUIS
(STL)...COLUMBIA (COU)...AND QUINCY (UIN):
ST. LOUIS
HIGH HIGH MINIMUM
1/2876 (1970)53 (1914)
1/2973 (2008)44 (1947)
COLUMBIA
HIGH HIGH MINIMUM
1/28 67 (2002) 53 (1914)
1/29 64 (2008) 44 (1938)
QUINCY
HIGH HIGH MINIMUM
1/28 63 (1914) 46 (1914)
1/29 63 (1914) 38 (1989)
&&
.PRELIMINARY POINT TEMPS/POPS...
ST LOUIS 23 45 22 31 / 30 10 0 0
QUINCY 19 37 14 26 / 30 10 0 0
COLUMBIA 23 46 20 36 / 20 10 0 5
JEFFERSON CITY 25 47 19 37 / 20 10 0 5
SALEM 23 42 22 30 / 40 20 0 0
FARMINGTON 25 48 22 34 / 40 10 0 0
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1131 PM CST THU JAN 24 2013
.AVIATION...06Z KGRI TAF. CONFIDENCE IS HIGH THAT THIS WILL BE A
BENIGN 24 HOURS AVIATION-WISE...WITH UNRESTRICTED VISIBILITY AND
ONLY LIMITED COVERAGE OF MID-HIGH CLOUDS NEAR/ABOVE 10 THOUSAND FEET.
SURFACE WINDS SPEEDS WILL LARGELY REMAIN BELOW 9KT...AS DIRECTION
SHIFTS FROM WESTERLY TONIGHT...TO VARIABLE FRIDAY AFTERNOON...TO
SOUTHERLY FRIDAY EVENING. THE ONLY POSSIBLE ISSUE OF NOTE IS A
BRIEF PERIOD OF BORDERLINE LOW LEVEL WIND SHEAR MAINLY BETWEEN
09Z-12Z EARLY THIS MORNING...AS NORTHERLY WINDS BETWEEN 1 AND 2
THOUSAND FEET AGL ACCELERATE TO BETWEEN 33-37KT. HOWEVER...THE
OVERALL BULK SHEAR MAGNITUDE DIFFERENCE BETWEEN THE SURFACE AND
THIS LEVEL SHOULD BARELY REACH/EXCEED 30 KNOTS...SO WILL CONTINUE
TO CONSIDER THIS A BIT MARGINAL FOR FORMAL INCLUSION IN THE TAF.
&&
.PREV DISCUSSION... /ISSUED 254 PM CST THU JAN 24 2013/
SHORT TERM...TONIGHT THROUGH FRIDAY AFTERNOON...PLENTY OF CLOUD
COVER ACROSS THE REGION THIS AFTERNOON AS A WARM FRONT ACROSS
WESTERN NEBRASKA IS SLOWLY PROGRESSING EASTWARD. THIS THICK CLOUD
COVER HAS LIMITED SOLAR HEATING TODAY...AND WITH A COLD AIRMASS
IN PLACE...HAVE STRUGGLED TO CLIMB OUT OF THE TEENS SO FAR IN
SPOTS...WHILE IN WESTERN NEBRASKA BEHIND THE WARM FRONT...
TEMPERATURES MANAGED TO CLIMB INTO THE LOWER 60S.
AS THIS WARM FRONT CROSS THE LOCAL AREA DURING THE EVENING
HOURS...EXPECT LOW TEMPERATURES TO BE REALIZED JUST AHEAD OF THE
BOUNDARY PASSAGE...WITH STEADY OR SLOWLY RISING TEMPERATURES
POSSIBLE OVERNIGHT. WITH HRRR AND NAM IN FAIR AGREEMENT...TAKING
THIS FRONT ACROSS KGRI AROUND 3Z...WENT AHEAD AND ADJUSTED HOURLY
TEMPERATURE GRIDS TO REFLECT LOW TEMPERATURES AT MOST AREAS BETWEEN
00Z AND 04Z THIS EVENING. OTHER THAN THE WARMER AIRMASS AND SWITCH
TO MORE SOUTHWESTERLY WINDS WITH THE PASSAGE OF THIS FRONT...NO
OTHER IMPACTS ARE EXPECTED.
FOR FRIDAY...EXPECT THE WARMER AIRMASS IN PLACE ACROSS THE LOCAL
AREA COMBINED WITH LIGHT WEST NORTHWESTERLY DOWNSLOPE FLOW...TO
HELP AFTERNOON TEMPERATURES SOAR PAST SEASONAL NORMALS...WITH MID
TO UPPER 40S FORECAST FOR MOST LOCATIONS. A PASSING SHORTWAVE OVER
THE TOP OF THE RIDGE IS EXPECTED TO REMAIN WELL TO THE NORTH OF
THE LOCAL AREA...WITH THE ASSOCIATED SURFACE COLD FRONT NOT
EXPECTED TO REACH THE LOCAL AREA. THEREFORE...WITH THINNING CLOUD
COVER BEHIND THE WARM FRONT AND LIGHT NORTHWESTERLY SURFACE
WINDS...A MOSTLY SUNNY AND PLEASANT END TO THE WEEK IS EXPECTED
ACROSS THE REGION.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY. MAIN FORECAST CONCERNS
WILL BE CHANCE FOR PRECIPITATION SATURDAY NIGHT INTO SUNDAY AND
AGAIN MONDAY NIGHT INTO TUESDAY AND TEMPERATURES THROUGH THE PERIOD.
A BROAD UPPER LEVEL RIDGE WILL DRIFT THROUGH THE AREA FRIDAY NIGHT
AND SATURDAY. TEMPERATURES FRIDAY NIGHT WILL STILL DROP INTO THE
TEENS AND LOWER 20S. DURING THE DAY WINDS WILL TURN TO THE SOUTH AND
WITH WARM ADVECTION THE TEMPERATURES SHOULD RISE INTO THE 40S TO
LOWER 50S.
BY SATURDAY NIGHT THERE IS AN UPPER LEVEL WAVE THAT MOVES INTO THE
AREA. THE SOUTH WINDS DURING THE DAY ON SATURDAY WILL BRING MOIST
AIR INTO THE AREA. BY SATURDAY NIGHT THERE ARE SOME DIFFERENCES IN
THE LOCATION OF THE PRECIPITATION DURING THE NIGHT. THE GFS BRINGS
MORE PRECIPITATION INTO THE AREA WHERE THE ECMWF AND THE NAM KEEP
THE PRECIPITATION FURTHER TO THE SOUTH. HAVE LOWERED THE CHANCES FOR
PRECIPITATION FOR THE NORTH AND WEST A BIT. THE QUESTION BECOMES
WHAT TYPE OF PRECIPITATION TO EXPECT. MOST OF THE NIGHT THERE WILL
BE RAIN AS THE TEMPERATURES WILL BE WARM ENOUGH FOR PRECIPITATION TO
REMAIN LIQUID. THE PROBLEM BECOMES TOWARD MORNING AS PRECIPITATION
SPREADS FURTHER TO THE NORTH. THERE COULD BE A BRIEF PERIOD OF SOME
FREEZING RAIN FURTHER NORTH. BY SUNDAY MORNING THE TEMPERATURES
SHOULD WARM UP AND PRECIPITATION SHOULD TURN TO RAIN ACROSS THE
AREA. BY LATER IN THE DAY ON SUNDAY THE RAIN SHOULD START TO MOVE
OUT OF THE AREA.
SUNDAY NIGHT AND MONDAY THERE WILL BE A DEVELOPING WAVE IN THE
WESTERN CONUS AND SOUTHWEST FLOW ACROSS THE AREA. THERE WILL BE WARM
ADVECTION AND MILD TEMPERATURES.
BY MONDAY NIGHT THE UPPER LEVEL WAVE STARTS TO AFFECT THE FORECAST
AREA. MODELS HAVE SOME DIFFERENCES IN THE PROGRESSION OF THE WAVE
ACROSS THE AREA. THE GFS IS FASTER WITH A MORE OPEN WAVE WHILE THE
ECMWF IS SLOWER WITH A CLOSED LOW. HAVE KEPT THE PRECIPITATION IN
ACROSS THE AREA FOR MONDAY NIGHT INTO TUESDAY WHICH IS CLOSER TO THE
GFS. THERE IS COLDER AIR MOVING INTO THE AREA BEHIND A COLD FRONT
THAT MOVES THROUGH MONDAY NIGHT. EXPECT RAIN OR SNOW MONDAY NIGHT
WITH THE COLDER AIR MOVING INTO THE AREA. THEN ON TUESDAY THERE WILL
BE SNOW FURTHER WEST OR NORTHWEST WHERE THE COLDER AIR IS...RAIN IN
THE SOUTHEAST AND A MIX OF RAIN OR SNOW POSSIBLE IN BETWEEN.
COLD AIR CONTINUES ACROSS THE AREA ON WEDNESDAY BUT THERE IS A
LITTLE WARM ADVECTION AND TEMPERATURES WARM A LITTLE FOR THURSDAY.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
325 AM CST FRI JAN 25 2013
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
325 AM CST FRI JAN 25 2013
MAIN FORECAST CONCERNS ARE ON SNOW AND WIND POTENTIAL TODAY...THEN
IF PRECIPITATION CAN OCCUR AND WHAT TYPE FOR SUNDAY INTO SUNDAY
NIGHT.
CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A POTENT TROUGH OFF THE PACIFIC NORTHWEST COAST...RIDGING
OVER THE NORTHERN U.S. ROCKIES INTO ALBERTA...A SHORTWAVE TROUGH
DIGGING INTO NORTHWEST MINNESOTA...AND A SHORTWAVE OVER SOUTHEAST
MINNESOTA. AHEAD OF THIS LATTER SHORTWAVE...WATER VAPOR...IR IMAGERY
AND SURFACE OBSERVATIONS SHOWED A LARGE EXPANSE OF MID AND HIGH
CLOUDS. RAP TROPOPAUSE ANALYSIS ALSO HAD A BROAD 120-140KT JET FROM
NEBRASKA TO OHIO DOWNSTREAM OF THE SHORTWAVE...ACTUALLY PLACING THE
FORECAST AREA IN THE SUBSIDENT LEFT ENTRANCE REGION. 00Z SOUNDINGS
FROM MPX...GRB AND DVN SHOWED A GREAT DEAL OF DRY AIR BELOW
700MB...WITH DEWPOINT DEPRESSIONS AS MUCH AS 30C. THIS DRY AIR HAS
BEEN EFFECTIVE AT MINIMIZING SNOWFALL OUT OF THE MID/HIGH CLOUDS
FROM REACHING THE SURFACE. THERE WAS HIGHER LOWER LEVEL MOISTURE OFF
TO THE WEST AT ABR AND OAX...NOTED BY ITS 00Z SOUNDING HAVING 850MB
DEWPOINT DEPRESSION BETWEEN 1-5C. THIS HAS BEEN SLOWLY ADVECTING
TOWARDS THE AREA REFLECTED BY SOUTHWEST 25-40KT WINDS ON PROFILER
AND VWP DATA. BETWEEN 06-08Z...SOME SNOW FINALLY GOT GOING...BUT THE
BACK EDGE BEHIND THE LEAD SHORTWAVE WAS RAPIDLY PUSHING EAST...WITH
KRST AND KCCY NOW DRY. TO THE NORTH...A BAND OF WARM ADVECTION SNOW
HAS BEEN ONGOING FROM NORTHERN MN INTO NORTHERN WI...DOWNSTREAM OF
THE NORTHWEST MN SHORTWAVE TROUGH. IN THE WAKE OF THIS SHORTWAVE
TROUGH...ANOTHER SURGE OF ARCTIC AIR WAS NOTED WITH TEMPERATURES IN
THE TEENS AND 20S BELOW ZERO OVER CENTRAL SASKATCHEWAN. THE COLD AIR
WAS IN THE WAKE OF A 1012MB SURFACE LOW IN NORTHWEST MN.
TODAY AND TONIGHT...MODELS ARE IN GOOD AGREEMENT DROPPING THE
SHORTWAVE TROUGH OVER NORTHWEST MINNESOTA ACROSS CENTRAL WISCONSIN
BY 18Z...THEN INTO SOUTHEAST LOWER MI BY 00Z. 500MB HEIGHTS SLOWLY
RISE THEREAFTER AS THE NORTHERN ROCKIES RIDGE SLIDES EASTWARD...
PLACING THE FORECAST AREA IN AN INFLECTION POINT BETWEEN A TROUGH
AND RIDGE AXIS BY 12Z SATURDAY. THE TROPOPAUSE DROPS NICELY THIS
MORNING WITH THE SHORTWAVE TROUGH MOVING IN...AS MUCH AS 100MB TO
NEAR 350MB ACROSS MUCH OF WISCONSIN BY 15Z. ALTHOUGH THIS IS GOOD
DYNAMIC FORCING...THE SCOURING OUT OF MID AND UPPER LEVEL MOISTURE
BY THE LEAD SHORTWAVE AHEAD OF THE TROUGH IS VERY PROBLEMATIC. AS
SUCH...MODELS HAVE BACKED OFF ON THE AMOUNT OF PRECIPITATION WITH
THE WARM ADVECTION AND DPVA AHEAD OF THE SYSTEM. THIS MATCHES TOO
WITH RADAR TRENDS...AND THUS HAVE SHORTENED THE END TIME OF THE
ADVISORY TO 12Z. IN FACT...WE MAY HAVE TO WAIT UNTIL THE
AFTERNOON...WHEN SNOW ACTUALLY LOOKS BETTER IN THE WAKE OF THE
SHORTWAVE TROUGH AND SURFACE LOW. THIS IS DUE TO COLD ADVECTION
COMBINING WITH LINGERING SURFACE MOISTURE TO PRODUCE CONVECTIVE
SNOW. THE 25.00Z NAM AND HIRES NMM RUNS ARE THE MOST BULLISH WITH
THE CONVECTIVE IDEA...WHILE ARW MODELS ARE NOT. IT APPEARS THE NMM
CORE MAY BE MOISTENING SURFACE DEWPOINTS UP TOO MUCH. TOOK A
COMPROMISE APPROACH WHICH RESULTS IN FLURRIES ALONG THE MS RIVER AND
SCATTERED SNOW SHOWERS NORTH OF I-94 WHERE THE BEST LOW LEVEL
INSTABILITY IS PRESENT. IN ADDITION TO THE SNOW...SETUP FOR THE
AFTERNOON IS FAVORABLE FOR WINDY CONDITIONS. THE COMBINATION OF COLD
ADVECTION...A TIGHT PRESSURE GRADIENT IN THE WAKE OF THE LOW...BEING
AT PEAK HEATING AND MIXING DEPTHS UP TO 875-900MB SHOULD YIELD GUSTS
IN THE 25-30 KT RANGE. EXPECT THE SNOW TO QUICKLY DIMINISH THIS
EVENING WITH LOSS OF HEATING AND THE SHORTWAVE TROUGH SHIFTING OFF.
WINDS LOOK TO TAKE SOME TIME DIMINISHING SINCE THE HIGH PRESSURE
AREA DOES NOT BUILD IN UNTIL LATE IN THE NIGHT...I.E. AT THE TIME OF
THE INFLECTION POINT IN THE FLOW AT 500MB. THE COMBINATION OF WIND
AND MUCH OF THE AREA STILL WITH NEAR BARE GROUND WILL KEEP LOWS
WARMER...ESPECIALLY COMPARED TO THE NAM WHICH HAS 5 INCHES ON THE
GROUND ACROSS THE FORECAST AREA. LEANED CLOSER TO THE ECMWF AND MAV
GUIDANCE FOR LOWS.
SATURDAY AND SATURDAY NIGHT...THE UPPER RIDGING OVER THE NORTHERN
ROCKIES IS PROGGED TO CONTINUE MARCHING EAST TOWARDS THE FORECAST
AREA DURING THIS TIME PERIOD...PUSHED ALONG BY TROUGHING OFF THE
PACIFIC NORTHWEST MOVING INLAND AS WELL AS AN UPPER LOW OFF THE
SOUTHERN CALIFORNIA COAST LIFTING INTO SOUTHEAST COLORADO. THE SHIFT
EAST OF THE UPPER RIDGE AXIS...REACHING EASTERN MN BY 12Z
SUNDAY...WILL SETUP A LOW LEVEL RETURN FLOW OVER THE FORECAST AREA
FOR THE AFTERNOON AND NIGHT. AN INCREASE OF MID/HIGH CLOUDS IS
LIKELY GIVEN THE WARM ADVECTION PATTERN...NOTED TOO BY 925MB TEMPS
CLIMBING FROM AROUND -12C AT 12Z SATURDAY TO -2 TO -6C BY 12Z
SUNDAY. THE QUESTION MARK IS LATE SATURDAY NIGHT...IF THE LOW LEVEL
MOISTURE WILL BE DEEP ENOUGH TO RESULT IN PRECIPITATION. THE 25.00Z
NAM/CANADIAN SUGGESTS THIS WOULD OCCUR FROM THE KANSAS CITY AREA
INTO NORTHEAST IOWA. COMPARED TO THE 25.00Z GFS/ECMWF/UKMET... THIS
SEEMS A LITTLE TOO FAR NORTH / FAST. THE OTHER MODEL GROUP KEEPS THE
BULK OF THE WARM ADVECTION PRECIPITATION SOUTH OF I-80. THUS...HAVE
KEPT THE ENTIRE PERIOD FROM 12Z SATURDAY TO 12Z SUNDAY DRY. WITH THE
WARMING 925MB TEMPS AND SOME SUN...HIGHS SHOULD BOUNCE BACK INTO THE
TEENS FOR SATURDAY. WARM ADVECTION PERSISTING THROUGH THE NIGHT PLUS
CLOUDS AROUND WILL LEAD TO RISING TEMPERATURES SATURDAY NIGHT.
SUNDAY AND SUNDAY NIGHT...THIS PERIOD REMAINS VERY PROBLEMATIC AND
UNCERTAIN. THE MAIN PROBLEM IS THE STRENGTH AND SPEED OF THE UPPER
LOW OFF THE SOUTHERN CALIFORNIA COAST LIFTING UP TOWARDS THE AREA ON
SUNDAY. THE SPREAD RANGES FROM:
1. A RELATIVELY STRONG 25.00Z GFS/CANADIAN...STILL SHOWING AT LEAST
A POTENT SHORTWAVE COMING THROUGH THE FORECAST AREA AROUND 06Z
MONDAY.
2. A REALLY WEAK 24.12Z/25.00Z ECMWF WHICH SHEAR THE UPPER LOW APART
AND HAVE ITS REMNANTS TRACK ALONG I-80.
THE 25.00Z NAM/UKMET LIE IN-BETWEEN THESE SCENARIOS. THE DIFFERENCES
NOT ONLY IMPACT WHETHER IT WILL PRECIPITATE...BUT ALSO WHAT TYPE
WOULD OCCUR IF IT DOES PRECIPITATE. THE ECMWF...BEING THE
WEAKEST...LIMITS THE AMOUNT OF MOISTURE RETURN INTO THE FORECAST
AREA FROM THE GULF OF MEXICO...AND NET RESULT IS A DRY FORECAST. THE
GFS/CANADIAN HAVE A MUCH STRONGER LOW LEVEL JET BECAUSE OF A STRONG
SHORTWAVE...THUS SPREAD PRECIPITATION OVER THE ENTIRE AREA. THIS
LATTER SCENARIO WOULD ALSO YIELD A SNOW TO SLEET TO FREEZING RAIN
SITUATION. ONCE THE SHORTWAVE GOES BY...THE PRECIPITATION DIMINISH.
SINCE ALL SCENARIOS SEEM PLAUSIBLE GIVEN THE MODELS HAVE MAINTAINED
GOOD CONTINUITY...HAVE COMPROMISED. THIS RESULTS IN A SLIGHT
LOWERING OF PRECIPITATION CHANCES FOR SUNDAY WHILE SUNDAY NIGHT WAS
PRETTY SIMILAR. FOR PRECIPITATION TYPE...BOTH SNOW AND FREEZING RAIN
SEEM EQUALLY LIKELY TO OCCUR...SINCE THERE ARE ALSO ISSUES WITH ICE
IN THE CLOUDS. HOPEFULLY MODELS WILL COME TOGETHER SOON. THE
TEMPERATURE FORECAST IS ALSO A COMPROMISE...BUT DECENT AGREEMENT
EXISTS THAT READINGS SHOULD GET UP CLOSE TO FREEZING ON
SUNDAY...THEN DROP VERY LITTLE SUNDAY NIGHT.
.LONG TERM...MONDAY THROUGH THURSDAY NIGHT
325 AM CST FRI JAN 25 2013
25.00Z ECMWF/GFS/GFS ENSEMBLES ALL DEPICT A FAIRLY SIMILAR SCENARIO
THROUGH THE LONG TERM PERIOD...WHILE THE 25.00Z CANADIAN IS AN
OUTLIER. THE PERIOD STARTS OFF WITH TROUGHING OVER THE WESTERN U.S.
WITH BROAD RIDGING DOWNSTREAM OVER THE EASTERN U.S.. MEANWHILE...A
POTENT SHORTWAVE/UPPER LOW OF ARCTIC ORIGIN IS PRESENT OVER THE
NORTHWEST TERRITORIES. THE CANADIAN IS THE ONLY MODEL THAT EJECTS
OUT THE SOUTHERN PORTION OF THE WESTERN UPPER TROUGH AND PHASES IT
WITH SOME NORTHERN STREAM ENERGY...RESULTING IN A POSSIBLE SNOWSTORM
FOR THE AREA ON TUESDAY. THE REST OF THE MODELS SAY THERE IS NO
PHASING...AND IN THE CASE OF THE ECMWF...THE SOUTHERN PORTION
CUTS-OFF. WITH NO PHASING...MUCH OF MONDAY THROUGH TUESDAY ENDS UP
DRY. HAVE MAINTAINED SOME LOW PRECIPITATION CHANCES DURING THIS TIME
PERIOD...SINCE THE 25.00Z ECMWF AND GFS DO DEPICT A LITTLE LIGHT QPF
FROM WEAK SHORTWAVES COMING THROUGH IN THE SOUTHWEST FLOW.
AFTER TUESDAY...THE POTENT SHORTWAVE/UPPER LOW OF ARCTIC ORIGIN IS
PROGGED TO DIVE DOWN INTO THE UPPER MIDWEST BY 12Z WEDNESDAY. THE
AREA THEN GENERALLY REMAINS UNDER TROUGHING THROUGH THURSDAY NIGHT.
AS SUCH...850MB AND 925MB TEMPS TAKE A NOSE-DIVE. LATEST 25.00Z
ECMWF KEEPS 850MB TEMPS BELOW -20C AFTER 18Z WEDNESDAY...A DECENT
DROP FROM BEING UP BETWEEN 0 AND +4C AT 00Z TUESDAY. THUS BELOW
NORMAL TEMPERATURES LOOK LIKELY. ANY PRECIPITATION SHOULD BE
CONFINED TO BEFORE THE COLD AIR COMES IN...WITH ARCTIC HIGH PRESSURE
DOMINATING AFTERWARDS.
&&
.AVIATION...
1111 AM CST THU JAN 24 2013
TIMING/CIGS/VSBYS REMAIN PROBLEMATIC WITH ASSOCIATED CLOUDS/EXPECTED
SNOW WITH SHORTWAVE TROUGH MOVING ACROSS THE REGION. CIGS HAVE
STARTED TO LOWER ACROSS THE REGION OVER THE LAST COUPLE HOURS...WITH
MORE RETURNS SHOWING UP ON RADAR...BUT NOT MUCH IN THE WAY OF -SN
REACHING THE SFC. RAP13/NAM12 CONTINUE TO SUGGEST RAPID SATURATION
OF THE DRY LOW LEVELS OVER THE NEXT FEW HOURS...WITH CIGS FOLLOWING
SUIT AND SOME -SN. NAM12 BUFKIT SOUNDINGS CAPTURED THE NEAR SFC DRY
LAYER THE BEST...COMPARED TO THE DVN 00Z SOUNDING...SO USING ITS
BUFKIT SOUNDINGS TO AID IN TIMING OF LOWER CIGS/-SN. STILL THINK A
DECENT CHANCE FOR SOME MVFR CIGS EARLY THIS MORNING...ALTHOUGH NOT
SOLD ON SUB 3SM -SN ANYMORE. SNOW ACCUMS LOOK MINOR...LESS THAN 1/2
AT KRST AND LESS THAN 1 INCH AT KLSE. IT WILL BE FLUFFY LOW WATER
CONTENT SNOW...SO IT WILL MOVE AROUND EASILY. DON/T EXPECT AN IMPACT
ON VSBYS UNLESS A FEW INCHES WOULD FALL.
BY LATE MORNING...A SFC COLD FRONT WILL BE SWEEPING THROUGH...WITH
COLD AIR ADVECTION AND SHARP LOW LEVEL LAPSE RATES BEHIND IT. THIS
COULD BRING A BETTER CHANCE FOR 2500 FT CIGS ALONG WITH SCT -SHSN.
ANY -SHSN COULD REDUCE VSBYS TO 2-3SM FOR A SHORT PERIOD...BUT NOT
ABLE TO TIME SO WILL LEAVE P6SM FOR NOW. IN ADDITION...EXPECT
BLUSTERY WINDS AS THEY TURN NORTHWEST BEHIND THE FRONT. THESE SHOULD
DIMINISH WITH NIGHT FALL AS HIGH PRESSURE STARTS TO BUILD IN FROM
THE PLAINS. LOOK FOR CLEARING SKIES ALSO...ALONG WITH AN END TO ANY
LINGERING -SHSN.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
325 AM CST FRI JAN 25 2013
WI...WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
WIZ017-029.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1142 PM CST THU JAN 24 2013
.UPDATE...NO CHANGE FROM PREVIOUS ISSUANCE
AREA 00Z RAOBS SHOWING THE VERY DRY LAYER...DEW POINT DEPRESSIONS
ON THE ORDER OF 30C IN THE 850-800MB LAYER...THAT HAVE BEEN
PREVENTING MUCH IN THE WAY OF GROUND TRUTH BELOW THE 15 TO 20 DBZ
RETURNS WITH THE INITIAL WAA ALL THE WAY BACK TO CENTRAL MN. SNOW
REPORTS HAVE BEEN LIMITED TO NRN MN AND NW WI. LATEST 01Z RAP AND
NEW 00Z NAM SHOW THE DRY LAYER AROUND 850 MB WILL BE TOUGH TO
SATURATE OVER THE CWA UNTIL AFTER 09Z...WITH REDUCED QPF AMOUNTS.
23Z HRRR DOES NOT BRING ANY QPF INTO THE CWA FOR THIS EVENT.
RAP AND NAM SOUNDINGS DO EVENTUALLY SATURATE. REDUCED QPF AND THUS
SNOW AMOUNTS ACROSS THE CWA...BUT STILL WORRIED ABOUT HIGH SNOW TO
LIQUID RATIOS WITH THE DEPTH OF OF THE SATURATED DENDRITIC GROWTH
ZONE...WITH SPC PROBABILITY OF 200 MB OR MORE AROUND 90 PCT ACROSS
THE FAR NORTH AND 50 PCT DOWN TO THE IL BORDER IN THE ERN CWA.
THE DEEP DGZ IS BEING SHOWN ON RAP SOUNDINGS IN THE EAST WITH
DECENT OMEGA...SO ONLY REDUCED THE AMOUNTS BY 1/2 INCH TO 1 INCH
FOR NOW.
AVIATION/06Z TAFS/...
WITH DELAY IN ONSET OF SNOW PLAN ON KEEPING VFR CONDITIONS AT TAF
SITES UNTIL 09Z AT KMSN AND 10Z-11Z EAST...THEN MVFR WITH EXPECTED
START OF STEADY LIGHT SNOW. WILL KEEP THE PERIOD OF IFR VSBYS AT
ERN SITES BETWEEN 15Z AND 18-19Z AS DEEP SNOW GROWTH ZONE
COINCIDENT WITH LIFT BRINGS POTENTIAL OF HIGH SNOW TO LIQUID
RATIOS. SNOW BEGINS TO TAPER OFF FROM WEST TO EAST AFTER
18Z...THOUGH MVFR CIGS AND VERY LIGHT SNOW OR FLURRIES WILL
CONTINUE UNTIL THE COLD FRONT CLEARS THE CWA AROUND 00Z. SOUNDINGS
ALSO SUPPORT WIND GUSTS OF 20 TO 25 KTS AT ERN SITES AND AROUND 20
KTS AT KMSN BY MID TO LATE MORNING...THEN DIMINISHING BEHIND THE
FRONT EARLY IN THE EVENING.
MARINE...
KEPT START TIME TO SMALL CRAFT ADVISORY ...THOUGH A FEW GUSTS HAVE
REACHED 24-25 KNOTS AT KENOSHA AND POINTS SOUTH...DO NOT EXPECT
FREQUENT CRITERIA LEVEL GUSTS TO KICK IN UNTIL 09Z AND WILL BE
MAINLY NORTH OF MILWAUKEE. NEXT SHIFT WILL HAVE TO MONITOR FOR
EITHER TO EXTEND THE AREA TO BE COVERED BY THE ADVISORY...OR START
EARLIER IF WINDS CLIMB.
PREV DISCUSSION... /ISSUED 410 PM CST THU JAN 24 2013/
SHORT TERM...
TONIGHT AND FRIDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
WILL SEE SOME LAKE EFFECT JUST BRUSH THE LAKE SHORE INTO THE
EVENING. NOT REALLY EXPECTING MUCH MORE THAN FLURRIES. BIGGER ISSUE
WILL BE WIDESPREAD SNOWFALL TONIGHT INTO FRIDAY. HIGH CONFIDENCE IN
ACCUMULATING SNOW ACROSS THE FORECAST AREA. MAIN PROBLEMS ARE TIMING
OF THE SNOW AND AMOUNTS. THE NAM AND GFS CONTINUE TO CHEW ON A LOT
OF DRY AIR THIS EVENING INTO EARLY TONIGHT...WHILE THE ECMWF AND
CANADIAN SATURATE A LOT FASTER. LEANED TOWARD THE SLOWER SOLUTIONS
BASED ON SHORT TERM MESO MODELS LOOKING SIMILAR TO THE NAM.
LIQUID TO SNOW RATIOS ARE THE OTHER ISSUE. SOUNDINGS ARE SHOWING A
VERY DEEP DENDRITE GROWTH LAYER...AS DEEP AS 350 MB IN THE NORTH.
WITH 1000-500 MB THICKNESS VALUES IN THE 520S AND AND TEMPERATURES
IN THE TEENS...EXPECTING VERY HIGH SNOW RATIOS. TOOK THEM AS HIGH 25
TO 1 IN THE NORTH...BUT WOULD NOT BE SURPRISED IF THEY GET EVEN
HIGHER. ENDED UP WITH SIMILAR STORM TOTAL SNOW AMOUNTS AS PREVIOUS
FORECAST...RANGING FROM 1 TO 2 INCHES IN THE SOUTHWEST FORECAST AREA
TO 3 TO 4 IN THE NORTHEAST. THOUGHT ABOUT A WINTER WEATHER ADVISORY
IN THE NORTHEAST...BUT WINDS STAY UNDER CONTROL WHILE THE SNOW IS
FALLING...AND AMOUNTS ARE GENERALLY BORDERLINE FOR AN ADVISORY. MAY
CAUSE A FEW ISSUES FOR THE MORNING COMMUTE...ESPECIALLY IN THE EAST
WHERE THE SNOW WILL HANG ON LATER INTO THE MORNING.
WIDESPREAD SNOW WILL WIND DOWN TOMORROW MORNING...WITH SNOW SHOWERS
POSSIBLY LINGERING INTO THE AFTERNOON...ESPECIALLY IN THE NORTHEAST.
LOOKS LIKE HIGHS ACTUALLY BACK NEAR NORMAL TOMORROW.
FRIDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE MEDIUM
BRISK NWLY WINDS AND COLD ADVECTION IN THE WAKE OF LOW PRESSURE
MOVING EAST ACROSS THE GREAT LAKES WILL RETURN AN ARCTIC AIRMASS
TO THE REGION FOR FRI NT. STEEP LOW LEVEL LAPSE RATES IN THE
EARLY EVENING COULD MAINTAIN FLURRIES OR LIGHT SNOW SHOWERS IN ERN
WI BEFORE CLEARING ARRIVES LATER IN THE EVENING. A 1030 MB POLAR
HIGH WILL PROGRESS EWD ACROSS SRN WI SAT INTO EARLY SAT EVENING
WITH LARGE SCALE RIDGING OVER THE PLAINS IN RESP0NSE TO AN
UPSTREAM UPPER TROUGH IN THE PACIFIC NW AND A SHORTWAVE TROUGH
MOVING INTO THE DESERT SW.
THE SHORTWAVE TROUGH OVER THE DESERT SW WILL THEN LIFT NEWD AND
EITHER TRACK INTO SRN WI OR REMAIN JUST TO THE SOUTH. THE
ASSOCIATED PRESSURE TROUGH/WARM FRONT WILL PRODUCE A GOOD BAND OF
PCPN BUT MODELS DIFFER ON PLACEMENT OF IT...SOME KEEPING THE MAIN
AREA TO THE SOUTH. KEPT POPS IN THE 40-60 PERCENT RANGE FOR NOW.
EITHER WAY...PCPN TYPE LOOKS MIXY. THERE COULD BE A BRIEF PERIOD OF
TOTAL COLUMN SATURATION LEADING TO SNOW BUT DRIER AIR ALOFT AND A
WARM LAYER COULD THEN RESULT IN FREEZING RAIN...FREEZING
DRIZZLE...AND SLEET. PUT IN LIGHT ICE AND SNOW ACCUMULATION INTO
SUNDAY FCST. THIS WOULD CONTINUE SUN NT AND POSSIBLY LINGER INTO
MONDAY ALTHOUGH TEMPS MAY WARM ABOVE FREEZING...MEANING RAIN FOR
PCPN TYPE.
TEMPS EXPECTED TO GRADUALLY WARM THROUGH THIS PERIOD WITH HIGHS
ABOVE FREEZING FOR MONDAY.
LONG TERM...
TUESDAY THROUGH THURSDAY...FORECAST CONFIDENCE LOW TO MEDIUM
MODELS DIFFER ON STRENGTH AND PLACEMENT OF CYCLOGENESIS FROM THE
PLAINS NEWD INTO ONTARIO CANADA FOR MON NT THROUGH WED...THUS THE
LOWER CONFIDENCE. GIVEN THE TRACK IS TO THE WEST AND NORTH STILL
WENT MILD WITH CHANCES OF RAIN THROUGH TUE. A STRONG COLD FRONT
WILL THEN SWEEP THROUGH THE STATE TUE NT WITH RAIN CHANGING TO
SNOW. BRISK NWLY WINDS AND COLD ADVECTION WILL PREVAIL INTO WED
WITH A POLAR AIRMASS RETURNING. HIGH PRESSURE TO THEN SETTLE OVER
THE REGION ON THU WITH BELOW NORMAL TEMPS EXPECTED.
AVIATION/00Z TAFS/...
MID AND HIGH LEVEL CLOUDS WILL KEEP SKIES MAINLY OVERCAST THROUGH
THE REMAINDER OF THE DAY. WILL CONTINUE TO SEE CIGS NEAR MVFR LATE
THIS AFTERNOON IN THE SOUTHEAST AS LAKE EFFECT SNOW SHOWERS BRUSH
THE LAKE SHORE. STILL NOT EXPECTING MUCH IN THE WAY OF
ACCUMULATION...IF ANYTHING AT ALL. OTHERWISE...DRY WEATHER AND VFR
CONDITIONS WILL PREVAIL THROUGH THE EVENING HOURS.
WILL SEE DETERIORATING CONDITIONS AFTER MIDNIGHT...AS WIDESPREAD
SNOWFALL MOVES INTO THE AREA. MVFR CONDITIONS ARE LIKELY...WITH
POSSIBLY LOWER VSBYS IN ANY AREAS OF MODERATE SNOWFALL. THE
WIDESPREAD SNOWFALL WILL WIND DOWN FRIDAY MORNING...THOUGH COULD
SEE A FEW SNOW SHOWERS LINGER INTO THE AFTERNOON. WILL LIKELY SEE
MVFR CIGS LINGER THOUGH MUCH OF THE DAY TOMORROW.
MARINE...
WILL LET CURRENT SMALL CRAFT ADVISORY EXPIRE AT SCHEDULED 22Z TIME.
LATEST WEBCAMS AND WAVE MODEL SHOW WAVES GENERALLY BELOW 4 FEET NOW.
SOUTH WINDS WILL PICK UP TONIGHT...WITH WAVES LIKELY EXCEEDING 4
FEET NORTH OF PORT WASHINGTON. WILL THUS ISSUE ANOTHER SMALL CRAFT
ADVISORY FOR LATE TONIGHT INTO FRIDAY AFTERNOON FOR THE NORTHERN
MARINE ZONE.
WINDS WILL BE CLOSE TO SMALL CRAFT ADVISORY ACROSS THE NEARSHORE
WATERS LATER FRIDAY INTO FRIDAY NIGHT. SEEMS TOO BORDERLINE FOR AN
ADVISORY AT THIS TIME THOUGH.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 3 AM TO 4 PM CST FRIDAY FOR LMZ643.
&&
$$
UPDATE...REM
TONIGHT/FRIDAY AND AVIATION/MARINE...DDV
FRIDAY NIGHT THROUGH THURSDAY...GEHRING
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1031 PM CST THU JAN 24 2013
UPDATED FOR LATEST TRENDS AND TO ADD SECTION FOR 06Z TAFS
.UPDATE...LEADING BAND OF ISENT LIFT SNOWS FINALLY GOT GOING
BETWEEN 900 PM AND 1000 PM. BUT BAND WAS SWEEPING EWD...WITH NOT
MUCH GOING ON BACK TO THE WEST. THINK REDEVELOPMENT WL OCCUR
SOONER OVER THE N...SO WL PROBABLY JUST HAVE SOME PERIODS OF SNOW
THERE. SHOULD BE A MORE DEFINED LULL IN THE SNOW ACRS C AND INTO
E-C WI. MAIN UPR SYSTEM LOOKS PRETTY IMPRESSIVE ON STLT
IMAGERY...AND COUNTING ON THAT GETTING BETTER SNOWS GOING LATE
TNGT INTO FRI.
SKOWRONSKI
&&
.PREV DISCUSSION...ISSUED AT 834 PM CST THU JAN 24 2013...
UPDATE...DRY AIR AT LOW-LEVELS REALLY PLAYING HAVOC WITH THIS
FCST. 00Z RAOBS FM GRB/MPX STILL VERY DRY AT LOW-LEVELS. DVN AND
ILX DRY TOO...INDICATING SLY FLOW WL CONT TO REINFORCE THE DRY
AIR AS PCPN FALLING FM MID-DECK ABV TRIES TO SATURATE IT. DON/T
HAVE A HIGH DEGREE OF CONFIDENCE IN HOW THIS WILL ALL ULTIMATELY
PLAY OUT...BUT CURRENT FCST IS GOING TO NEED SOME ADJUSTMENTS.
FIRST...GOING TO DELAY THE START OF THE ADVISORY FOR MANY AREAS.
WL ALLOW THE FAR NW TO START AT 03Z AS PLANNED...BUT HOLD OFF ON
THE REST OF THE N UNTIL AT LEAST 06Z. INITIAL SURGE OF ISENT LIFT
PCPN MAY NOT COME TOGETHER UNTIL IT IS NE OF THE GRB/FOX CITIES
AREA...SO WL DELAY ADVISORY FOR THESE AREAS UNTIL 09Z.
ON THE FLIP SIDE...LAKE-EFFECT SNOW BAND CONTD TO BACK WWD TOWARD
THE SHORE. BAND HAD SEVERAL EMBEDDED MESO-VORTICIES...AND RADAR
RETURNS SUGGESTED SOME DECENT SNOWFALL RATES. PLUS...BAND COULD
INTENSIFY WHEN IT STARTS TO GET SEEEDED FM ABV. SO...SINCE WE ARE
GOING TO HAVE AN ADVISORY FOR THE LAKESHORE ANYWAY...WL MOVE THE
START TIME OF THAT UP TO 03Z TO ACCOUNT FOR THE LAKE-EFFECT.
EXPERIENCE HAS SHOWN THAT WHENEVER YOU NEED TO DELAY THE ONSET OF
AN EVENT SUCH AS THIS...YOU ALMOST ALWAYS NEED TO CHOP SNOW TOTALS
AS WELL. WITH ISENT LIFT PCPN NOW LOOKING LESS SIG...MUCH OF THE
ACCUMULATION WL NEED TO COME FM UPR SHRTWV. VORT PROGGED TO TRACK
SE ACRS THE FCST AREA...RIGHT TOWARD GRB TOMORROW AFTN. THAT
SUGGESTS MAX SNOWS OVER NRN/NE WI. WL LEAVE TOTALS SIMILAR TO PREV
FCST THERE...BUT CUT BACK FARTHER TO THE S AND W.
UPDATED PRODUCT SUITE OUT ASAP.
SKOWRONSKI
DISCUSSION ISSUED AT 615 PM CST THU JAN 24 2013...
UPDATE...DONT LIKE AT ALL THE WAY THE SITN IS EVOLVING THIS
EVENING. LOW-LEVELS REMAIN VERY DRY...AND SLY FLOW AHEAD OF THE
INCOMING SYSTEM WL CONT TO REINFORCE THE DRY AIR FM THE S. THAT
COULD PLAY HAVOC WITH THE ONSET OF PCPN...THE TIMING OF THE
ADVISORY...AND SNOW AMNTS. RAP PAINTING A MUCH DIFFERENT PICTURE
THAN THE REST OF THE GUID. IT HAS BAND OF SNOW IN ISENT LIFT ZONE
TRYING TO CONSOLIDATE AS IT WORKS ACRS THE FCST AREA THIS EVENING.
BUT THEN THAT BAND PUSHES OFF TO THE E AFTER MIDNIGHT...WITH AT
LEAST A SEVERAL HR LULL IN THE PCPN BEFORE LOW-LEVELS SATURATE
AGAIN AND PCPN WITH THE UPR SHRTWV ARRIVES. IT/S RATHER HARD TO
ARGUE WITH THAT IDEA GIVEN THE CURRENT RADAR TRENDS...AND THE VERY
LIMITED NUMBER OF OB SITES REPORTING SNOW IN MN/NW WI EARLY THIS
EVENING. NOT READY TO MAKE ANY SIG CHGS TO THE FCST YET... THOUGH
THAT MAY BECOME NECESSARY IF CURRENT RADAR/OB TRENDS HOLD.
ONE AREA THAT COULD SEE SNOW A LITTLE EARLIER THAN EXPECTED IS THE
LAKESHORE RGN OF MTW COUNTY. MESOSCALE CIRCULATION WORKING NWD
OVER WRN LAKE MICHIGAN COULD GET SOME SHSN AND FLURRIES INTO
LAKESHORE AREAS DURING THE EVENING.
GOING TO UPDATE THE FCST FOR THE LAKE-EFFECT NOW...BUT HOLD OFF
MAKING ANY MORE SUBSTANTIAL CHGS FOR NOW.
SKOWRONSKI
DISCUSSION ISSUED AT 541 PM CST THU JAN 24 2013...
SHORT TERM...TONIGHT AND FRIDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH
PRESSURE CENTERED ACROSS THE STATE EARLY THIS AFTERNOON. MID AND
HIGH CLOUDS ARE ALREADY ON THE INCREASE...HOWEVER...AHEAD OF THE
NEXT SHORTWAVE TROUGH MOVING ESE OVER SOUTHERN SASKATCHEWAN. RADARS
ARE PUSHING AN AREA OF LIGHT TO MODERATE SNOW OVER FAR NORTHERN
NORTH DAKOTA AND SOUTHERN MANITOBA AND IS STARTING TO ENTER NORTHERN
MINNESOTA. AS THE SHORTWAVE TRACKS TOWARDS THE REGION TONIGHT AND
OVER THE REGION ON FRIDAY...SNOWFALL AMOUNTS AND HEADLINES ARE THE MAIN
FORECAST CONCERNS.
TONIGHT...SHORTWAVE TROUGH OVER THE SOUTHERN CANADIAN PRAIRIE WILL
DIVE SOUTHEAST TONIGHT ON ITS WAY TO THE ARROWHEAD OF MINNESOTA BY
12Z FRIDAY. AHEAD OF THE SHORTWAVE...FORCING IN THE FORM OF DPVA
AND ISENTROPIC ASCENT ON THE 280-285K SURFACES WILL SPREAD SOUTHEAST
WHICH WILL LEAD TO A WARM ADVECTION BAND ENTERING NW WISCONSIN BY
00-03Z AND NORTH-CENTRAL AND NORTHEAST WISCONSIN IN THE 03-06Z TIME
PERIOD. PLENTY OF UNCERTAINTY WITH THE DETAILS...INCLUDING WHERE
AND WHEN THE BAND ENTERS THE FORECAST AREA...AND ALSO SNOWFALL
RATIOS. THE LATEST SHORTER RANGE GUIDANCE INDICATES THAT A WARM
ADVECTION SNOW BAND WILL DIVE SE INTO RHI-GRB LINE BETWEEN 03-06Z
BEFORE WIDESPREAD SNOW ENTERS THE AREA AFTER MIDNIGHT. FGEN AND
INSTABILITY ALOFT ARE NOT PARTICULARLY IMPRESSIVE...BUT MICROPHYSICS
ARE A DIFFERENT STORY. BUFKIT SOUNDINGS FOR THE BOTH THE NAM/GFS
INDICATE AN ISOTHERMAL LAYER FROM THE SURFACE TO ABOUT
575MB...FIRMLY IN THE DENDRITIC GROWTH ZONE. ASCENT WONT OCCUPY
THIS ENTIRE LAYER...BUT SHOULD COINCIDE FOR ABOUT 200MB FROM LATE
THIS EVENING THROUGH EARLY FRIDAY MORNING. AS A RESULT...DESPITE
MEDIOCRE FORCING AND INSTABILITY...SHOULDNT TAKE MUCH QPF IN ORDER
TO GET A SUBSTANTIAL AMOUNT OF SNOW. ESTIMATING SNOWFALL RATIOS OF
20-30:1 WILL YIELD WIDESPREAD 2-4 INCH AMOUNTS BY MORNING FROM
NORTH-CENTRAL WISCONSIN TO THE SOUTHERN FOX VALLEY. WILL ADD
WAUPACA AND THE REST OF THE FOX VALLEY/LAKESHORE TO THE WINTER
WEATHER ADVISORY SINCE THE SNOW WILL BE FLYING DURING THE MORNING
RUSH HOURS WHERE 2-3 INCHES WILL PROBABLY ALREADY HAVE FALLEN. WILL
ALSO BUMP UP THE START TIME OVER N-C WISCONSIN TO START IT AT 03Z.
FRIDAY...THE SHORTWAVE WILL PASS ACROSS THE AREA DURING THE
DAY...AND IT WILL PUSH A SURFACE LOW ACROSS NORTHERN WISCONSIN
DURING THE AFTERNOON. FORCING WILL BE SHIFTING TO THE SOUTHEAST
FRIDAY MORNING...WHICH MAY LEAD TO SOME DRY SLOTTING OVER CENTRAL
AND EAST-CENTRAL WISCONSIN. BUT DEEPER COMMA HEAD MOISTURE DOES PASS
OVER NORTH-CENTRAL AND NORTHEAST WISCONSIN DURING THE DAY...WHERE
HIGHER ACCUMS SHOULD RESIDE. WILL STILL HAVE THE VERY GOOD SNOW
RATIOS FOR MUCH OF THE DAY...AND CAN SEE ADDITIONAL 1-2 INCHES OVER
NORTHEAST HALF OF THE FORECAST AREA...AND LESS THAN AN INCH OVER THE
SOUTHWEST. WINDS MAY START TO GET GUSTY LATE IN THE
AFTERNOON...WHICH MAY LEAD TO MINOR BLOWING AND DRIFTING SNOW.
HIGHS IN THE MID TEENS TO MID 20S.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
CLIPPER SYSTEM WILL CONTINUE TO MOVE AWAY FROM THE AREA FRIDAY
NIGHT. COULD BE A BRIEF PERIOD OF GUSTY WINDS AND BLOWING AND
DRIFTING OF THE SNOW AS SYSTEM MOVES AWAY AND COLDER AIR FILTERS
INTO THE REGION. WILL MENTION IT IN THE HAZARDOUS WEATHER OUTLOOK...
BUT WILL NOT HAVE IT IN THE GRIDS DUE TO THE BRIEF NATURE OF THE
EVENT. OTHERWISE...LAKE EFFECT SNOW SHOWERS WILL CONTINUE THROUGH
MOST OF THE NIGHT ACROSS THE FAR NORTH. HAVE INCREASED POPS INTO
THE CATEGORICAL RANGE FOR VILAS COUNTY AND INCREASED POPS OVER
THE REMAINDER OF THE NORTH AS WELL. DID ADD A CHANCE OF FLURRIES
THROUGH MOST OF THE NIGHT ACROSS THE SOUTH UNTIL CLEARING ARRIVES.
DID SLOW THE ARRIVAL OF THE CLEARING BY SEVERAL HOURS...MAINLY DUE
TO COLD NORTHERLY FLOW OFF THE WARMER WATERS OF LAKE SUPERIOR.
MODELS DO SHOW DRYING OF THE 850MB MOISTURE TOWARDS 12Z ACROSS
CENTRAL WISCONSIN. ON SATURDAY...DID LEAVE A FEW LINGERING FLURRIES
FOR A FEW HOURS SATURDAY MORNING ACROSS THE FAR NORTH/NORTHEAST.
WITH SUCH A COLD AIR MASS IN PLACE...ANY CUMULUS CLOUD COULD PRODUCE
A FEW FLURRIES BEFORE DISSIPATING.
NEW QUESTIONS ARISE FOR THE SATURDAY NIGHT PERIOD. LATEST WRF/CANADIAN
NOW PRODUCE A FEW INCHES OF LIGHT SNOW ACROSS CENTRAL AND NORTHERN
WISCONSIN...WHILE THE GFS/ECMWF DO NOT SHOW THIS FEATURE. WILL HAVE
A SLIGHT CHANCE OF LIGHT SNOW ACROSS THE NORTH FOR NOW.
CONFIDENCE REMAINS LOW THROUGHOUT THE REST OF THE FORECAST PERIOD
WITH HANDLING OF SYSTEM SUNDAY NIGHT AND SUNDAY NIGHT...AND AGAIN
TUESDAY. LATEST CANADIAN/ECMWF MODELS HAVE SHIFTED SYSTEM SUNDAY/
SUNDAY NIGHT FURTHER SOUTH AND WOULD JUST CLIP OUR FAR SOUTH. SINCE
MODELS HAVE BEEN JUMPING AROUND SIGNIFICANT ON LOCATION OF THIS SYSTEM...
WILL CONTINUE WITH PERSISTENCE FOR NOW UNTIL THERE IS A CLEAR
TREND. PRECIPITATION TYPE ISSUES STILL CONTINUE WITH THIS SYSTEM
WILL PRECIPITATION COULD END UP AS LIGHT SNOW...FREEZING RAIN OR
SLEET.
THE SYSTEM FOR TUESDAY CONTINUE TO BE PROBLEMATIC AS THE ECMWF
CONTINUES TO GO BACK AND FORTH WITH SURFACE LOW TRACKING WEST OF
GREEN BAY. THE GFS CONTINUED THIS TREND ON THE MORNING RUN...BUT 12Z
ECMWF HAS NO SUCH FEATURE ON THIS RUN. WILL CONTINUE WITH PERSISTENCE
WITH THIS PERIOD AS WELL UNTIL MODELS CONVERGE ON A CLEAR SOLUTION.
AT OR ABOVE NORMAL TEMPERATURES ARE EXPECTED MONDAY AND TUESDAY...THEN
BELOW NORMAL TEMPERATURES ARE EXPECTED LATE NEXT WEEK AS ANOTHER
SURGE OF ARCTIC AIR WILL SWEEP INTO THE NORTHERN UNITED STATES.
&&
.AVIATION...FOR 06Z TAF ISSUANCE. A BRIEF PERIOD OF IFR CONDITIONS
EXPECTED WITH SNOW BAND SWEEPING ACRS C AND E-C WI. SHOULD SEE A
PERIOD OF VFR CONDITIONS FOR SEVERAL HRS AFTER THAT...BEFORE
CONDITIONS WORSEN AGAIN.
SKOWRONSKI
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 3 AM TO 3 PM CST FRIDAY FOR
WIZ037>039-048-049.
WINTER WEATHER ADVISORY UNTIL 3 PM CST FRIDAY FOR WIZ040-050.
WINTER WEATHER ADVISORY UNTIL NOON CST FRIDAY FOR WIZ011>013-
019>021-030-031.
WINTER WEATHER ADVISORY UNTIL NOON CST FRIDAY FOR WIZ005-010-018.
WINTER WEATHER ADVISORY UNTIL 3 PM CST FRIDAY FOR WIZ022-073-074.
&&
$$
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
639 AM EST FRI JAN 25 2013
.SYNOPSIS...
HIGH PRESSURE WILL EXTEND ACROSS THE REGION TODAY. A COLD FRONT
WILL DROP THROUGH LATE FRIDAY NIGHT. HIGH PRESSURE WILL BUILD IN
SATURDAY THROUGH EARLY NEXT WEEK. A WARMING TREND IS EXPECTED NEXT
WEEK BEFORE ANOTHER COLD FRONT SWEEPS THROUGH THE SOUTHEAST
WEDNESDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
ONLY CHANGE FOR THE SUNRISE UPDATE WAS TO INCREASE HIGHS 1-2
DEGREES ACROSS THE EASTERN HALF OF THE FORECAST AREA. HIGH
RESOLUTION MODELS ARE INSISTENT THAT THE WEDGE WILL ERODE INTO THE
SOUTHERN MIDLANDS AND CSRA LATER THIS AFTERNOON ALLOWING
TEMPERATURES TO RISE INTO THE UPPER 50S TO NEAR 60 WELL INLAND.
WILL LET THE DAY CREW MAKE THE DECISION TO MAKE ANY ADDITIONAL
CHANGES AFTER THE 12Z MODEL DATA ARRIVE AND ARE EVALUATED.
OVERVIEW: THE COLD FRONT WHICH PASSED THROUGH YESTERDAY AFTERNOON IS
LOCATED WELL TO THE SOUTH WITH MODIFIED ARCTIC AIR OOZING INTO THE
REGION. THE ARCTIC AIRMASS IS BEING MODIFIED SIGNIFICANTLY IN THE
SAVANNAH-DARIEN-LUDOWICI CORRIDOR WHERE DEWPOINTS REMAIN IN THE
LOWER 30S TO LOWER 40S WITH SURFACE TEMPERATURES STILL IN THE 40S
AS OF 25/08Z...COURTESY OF MARINE INFLUENCES VIA NORTHEAST WINDS.
EARLY MORNING SURFACE ANALYSIS SHOWS A WELL DEFINED INSITU WEDGE
IS IN PLACE ACROSS NORTH CAROLINA...SOUTH CAROLINA AND GEORGIA
WITH THE CORE OF THE WEDGE HIGH CENTERED OVER THE MID-ATLANTIC
STATES. THE WEDGE WILL EXTEND ACROSS THE CAROLINA PIEDMONT TODAY
AS THE REGION REMAINS CAUGHT IN A STIFF NORTHWEST FLOW REGIME
ALOFT. THE FORECAST CONCERNS TODAY CENTER AROUND PINNING DOWN HIGH
TEMPERATURES AND RAIN CHANCES.
RAIN CHANCES: THE 25/00Z MODELS ARE FINALLY CONVERGING ON A
MORE UNIFIED SOLUTION FOR RAIN CHANCES TODAY. ALL AGREE THAT THE
BETTER PROBABILITIES FOR MEASURABLE RAINFALL WILL BE DISPLACED
WELL TO THE NORTH AND WEST OF THE LOCAL FORECAST AREA COINCIDENT
WITH THE STRONGEST ISENTROPIC ASSENT ATOP THE INLAND WEDGE. THE
AIRMASS OVER THE WEDGE WILL SIMPLY REMAIN TOO DRY TO SUPPORT
MEASURABLE RAINFALL THIS FAR SOUTH UNTIL POSSIBLY VERY LATE IN THE
AFTERNOON WELL INLAND. THE MOST RECENT RUNS OF THE HIGHER
RESOLUTION NSSL WRF...H3R AND RAP ALSO AGREE WITH THIS SCENARIO SO
WILL LOWER POPS ACROSS THE BOARD...KEEPING A SLIGHT CHANCE FOR
SHOWERS THIS AFTERNOON FOR THE COUNTIES BORDERING THE
CSRA...SOUTHERN MIDLANDS AND THE NORTHERN SOUTH CAROLINA COAST TO
BETTER BLEND WITH THE COLLABORATED HIGHER POP FORECASTS FROM THE
COLUMBIA AND WILMINGTON WEATHER FORECAST OFFICES.
TEMPERATURES: IT WILL BE ANOTHER EXTREMELY CHALLENGING HIGH
TEMPERATURE FORECAST TODAY. MOST OF THE MODELS SHOW THE WEDGE
HOLDING FIRM FOR MUCH OF THE MORNING...BUT GRADUALLY BREAK IT DOWN
DURING THE AFTERNOON AS THE WEDGE HIGH SLOWLY SHIFTS OFF THE
NORTH CAROLINA/VIRGINA COAST. ALTHOUGH PRECIPITATION FALLING OVER
THE CENTRAL/NORTHERN MIDLANDS...THE PEE DEE AND NORTH CAROLINA
WILL LIKELY HOLD A PIECE OF THE WEDGE IN PLACE AS STRONG DIABATIC
PROCESSES TAKE HOLD...THE LACK OF A STRONG CONFLUENT FLOW OVER THE
MID-ATLANTIC SUGGESTS THE WEDGE HIGH WILL NOT BE LOCKED IN AS IS
TYPICAL IN MORE CLASSIC COLD AIR DAMMING EVENTS...HENCE THIS WEDGE
IS MORE INSITU IN NATURE. WOULD NORMALLY UTILIZE THE COLDER SIDE
OF THE GUIDANCE ENVELOP ACROSS INLAND AREAS GIVEN THE USUAL MODEL
BIASES OF BREAKING WEDGES DOWN TOO QUICKLY...BUT SINCE LITTLE IF
ANY PRECIPITATION WILL FALL ACROSS THE AREA OR THE SOUTHERN
MIDLANDS TODAY...THE QUICKER EROSION OF THE WEDGE SEEMS QUITE
PLAUSIBLE. HOWEVER...THE EXACT TIMING IS STILL UNKNOWN WHICH WILL
HAVE A MAJOR IMPACT ON HOW MUCH WARMING WILL OCCUR ACROSS FAR
INLAND AREAS. WILL ONLY NUDGE HIGHS UP A FEW DEGREES INTO THE
UPPER 40S/LOWER 50S ACROSS FAR INLAND AREAS PER COORDINATION WITH
THE PEACHTREE CITY...WILMINGTON AND COLUMBIA OFFICES...HOWEVER
WARMER TEMPERATURES WILL BE POSSIBLE IF THE WEDGE ERODES QUICKER
THAN WHAT IS EXPECTED.
THERE WILL BE A LARGE THERMAL GRADIENT ACROSS SOUTHEAST SOUTH
CAROLINA AND SOUTHEAST GEORGIA TODAY WITH HIGHS RANGING FROM THE
UPPER 40S/LOWER 50S WELL INLAND TO THE MID 60S ACROSS PARTS OF
LIBERTY...LONG AND MCINTOSH COUNTIES. MODELS SHOW SKIES BREAKING
ACROSS THE FAR SOUTH AS THE WEDGE FRONT ERODES INLAND AND THERE IS
A POTENTIAL FOR TEMPERATURES TO WARM EVEN MORE. GIVEN ALL OF THE
UNKNOWNS TODAY...FURTHER REFINEMENTS TO THE TEMPERATURE FORECAST
WILL MOST CERTAINLY BE NEEDED AS THE DAY PROGRESSES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
TONIGHT...COLD AIR DAMMING WILL BREAK DOWN QUICKLY THIS EVENING AS
THE WEDGE HIGH SHIFTS OFFSHORE AND A COLD FRONT APPROACHES FROM
THE NORTHWEST. IT LOOKS AS THOUGH THE FRONT WILL BE QUITE A BIT
SLOWER TO PASS THROUGH THE REGION TONIGHT...LIKELY NOT PUSHING
OFFSHORE UNTIL SATURDAY. UPPER LEVEL SUPPORT LOOKS MEAGER FOR
MEASURABLE RAINFALL TO OCCUR WITH THE FRONT...BUT SEVERAL MODELS
DO SPIT OUT A FEW HUNDREDTHS OF RAIN OVER SOME AREAS OVERNIGHT.
FORECAST SOUNDINGS SUGGEST THE ATMOSPHERE WILL BE MOIST ENOUGH TO
SUPPORT AT LEAST ISOLATED SHOWERS...SO WILL MAINTAIN A SLIGHT
CHANCE OF SHOWERS...MAINLY ACROSS THE WESTERN AND NORTHERN AREAS
TONIGHT. LOWS WILL RANGE FROM THE LOWER 40S INLAND TO THE LOWER-
MID 50S ALONG THE COAST.
SATURDAY...THE COLD FRONT WILL CONTINUE TO DROP THROUGH THE
FORECAST AREA SATURDAY MORNING...PROGRESSING STEADILY SOUTH OF THE
REGION BY THE AFTERNOON HOURS. FORECAST SOUNDINGS SUGGEST ANY LOW
TO MID LEVEL MOISTURE WILL QUICKLY DISSIPATE BY MID MORNING...THUS
ANY POTENTIAL FOR PRECIPITATION WITH THE DESCENDING FRONT REMAINS
QUITE LOW. HAVE THUS MAINTAINED POPS BELOW 15 PERCENT. A DECENT
HIGH TEMPERATURE GRADIENT COULD SET UP SATURDAY AFTERNOON...AS THE
NORTHERN AREAS QUICKLY FALL WITHIN COOLER NORTHERLY FLOW BEHIND
THE FRONT...WHILE SOUTHERN SECTIONS REMAIN UNDER A MORE MILD WEST
FLOW. BOTH NAM AND GFS MODEL GUIDANCE HAVE TRENDED WARMER WITH
TEMPERATURES FOR SATURDAY...AND HAVE THUS INDICATED HIGHS RANGING
FROM THE LOW 60S CHARLESTON TRI COUNTY AREA TO NEAR 70 DEGREES
ALONG THE ALTAMAHA RIVER IN FAR SOUTHEAST GEORGIA. LOW
TEMPERATURES SATURDAY NIGHT WILL BE NOTABLY COOLER HOWEVER...AS
HIGH PRESSURE BUILDING FROM THE NORTH ADVECTS A COLDER AIR MASS
ACROSS THE ENTIRE FORECAST AREA OVERNIGHT. LOW TEMPERATURES WILL
FALL INTO THE LOWER 30S NORTH/NORTHWEST TO THE UPPER 30S SOUTHEAST
GEORGIA.
SUNDAY...A HIGH PRESSURE WEDGE WILL BE ESTABLISHED ACROSS THE MID
ATLANTIC AND SOUTHEAST STATES. THIS PATTERN WILL CREATE ANOTHER
DECENT NORTHWEST TO SOUTHEAST TEMPERATURE GRADIENT...WITH COOLER
THAN NORMAL HIGHS IN THE MID 50S NORTHERN SOUTH CAROLINA COUNTIES
AND MORE SEASONAL TEMPERATURES IN THE LOWER 60S SOUTH OF THE
SAVANNAH RIVER. SOME MID TO HIGH LEVEL CLOUDS MOVING INTO THE AREA
FROM THE WEST WILL HELP MODERATE LOW TEMPERATURES SUNDAY NIGHT IN
THE UPPER 30S FAR INLAND TO THE LOWER 40S CLOSER TO THE COAST.
RIDGING AT THE SURFACE AND ALOFT...ALONG WITH LIMITED DEEP
MOISTURE...SUGGESTS DRY CONDITIONS FOR SUNDAY.
MONDAY...AS THE CENTER OF SURFACE HIGH PRESSURE SLIPS OFF THE EAST
COAST...A WELL-DEFINED COASTAL TROUGH WILL LIKELY DEVELOP OVER THE
SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA NEARSHORE WATERS.
WINDS WILL STEADILY VEER SOUTHEAST TO SOUTH AS THE DAY
PROGRESSES...AND EXPECT WARMER HIGH TEMPERATURES IN THE 60 DEGREE
RANGE AS A RESULT. WEAK CONVERGENCE ASSOCIATED WITH THE COASTAL
TROUGH COULD PRODUCE ISOLATED SHOWERS JUST OFF THE
COASTLINE...HOWEVER CONFIDENCE IN COVERAGE IS TOO LOW TO RAISE
POPS ABOVE ABOUT 12 PERCENT AT THIS TIME.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
SURFACE HIGH PRESSURE WILL SETTLE OVER THE NEARBY ATLANTIC WATERS
MONDAY NIGHT THROUGH EARLY WEDNESDAY...BEFORE A DEEP UPPER TROUGH
SWEEPS TOWARD THE AREA FROM THE NORTHERN GREAT PLAINS AND SHIFTS A
COLD FRONT INTO THE EAST COAST STATES. EXPECT A DECENT WARMING
TREND FOR TUESDAY AND WEDNESDAY...AS THE REGION REMAINS WITHIN
WARM SOUTHERLY FLOW DOWNSTREAM OF THE APPROACHING COLD FRONT.
TEMPERATURES WILL PEAK IN THE LOW TO MID 70S AWAY FROM THE
IMMEDIATE COASTLINE EACH AFTERNOON. RAIN CHANCES WILL THEN
INCREASE FROM WEST TO EAST EARLY WEDNESDAY AS THE FRONT PUSHES
INTO THE FORECAST AREA...AND HAVE INDICATED POPS IN THE 30 PERCENT
RANGE BY WEDNESDAY NIGHT WITH THE FRONT AND DEEPEST MOISTURE
DIRECTLY OVER THE SOUTHEAST STATES. NUMERICAL MODEL GUIDANCE
DIVERGES QUITE A BIT REGARDING THE PATTERN EVOLUTION AFTER THE
FRONT PUSHES OFFSHORE ON THURSDAY. AT THIS POINT...HAVE GENERALLY
LEANED TOWARD PERSISTENCE WITH A CLEANER FRONTAL PASSAGE AND
COOLER TEMPERATURES THURSDAY AND FRIDAY. HOWEVER...HAVE MAINTAINED
JUST SLIGHT RAIN CHANCES THROUGH FRIDAY TO ACCOUNT FOR MODEL
DISCREPANCIES LATE IN THE PERIOD.
&&
.AVIATION /11Z FRIDAY THROUGH TUESDAY/...
LOW CLOUDS HAVE BEEN IN AND OUT AT KSAV AND HAVE REMAINED JUST
SOUTH OF KCHS OVER THE PAST FEW HOURS. SATELLITE SHOWS AN
EXPANDING AREA OF CIGS 1500-2500 FT JUST WEST OF KSAV AND SHOULD
MOVE INTO THAT TERMINAL SHORTLY AND REMAIN THROUGH ABOUT 17Z
BEFORE BREAKING TO VFR AS THE WEDGE ERODES INLAND. AT KCHS...MVFR
CIGS WILL BE A BIT SLOWER TO ARRIVE...LIKELY 15-16Z AND REMAIN
THROUGH EARLY AFTERNOON BEFORE LIFTING TO VFR. VFR IS ANTICIPATED
FOR THE REMAINDER OF THE 12Z TAF PERIOD.
EXTENDED AVIATION OUTLOOK...THERE IS A LOW CHANCE OF MVFR
CIGS/VSBYS FRIDAY NIGHT INTO EARLY SATURDAY WITH A PASSING COLD
FRONT.
&&
.MARINE...
TODAY...WINDS WILL GRADUALLY SUBSIDE OVER THE LOCAL MARINE AREA
TODAY. WINDS ARE FORECAST TO GRADUALLY VEER MORE ONSHORE AND
EVENTUALLY TO THE SOUTH AS THE INLAND WEDGE ERODES. WINDS MAY
ACTUALLY GO VARIABLE FOR A FEW HOURS ACROSS THE GEORGIA WATERS
THIS AFTERNOON AS BOTH THE NAM/RAP SHOW WEAK LOW PRESSURE OR WAVE
FORMING ALONG A SUBTLE COASTAL THROUGH OFFSHORE OF THE GEORGIA
COAST. SEAS WILL SUBSIDE TO 2-4 FT NEARSHORE WATERS AND 3-5 FT
OFFSHORE WATERS BY AFTERNOON.
TONIGHT...WINDS WILL VEER SOUTHWEST AHEAD OF A SLOW MOVING COLD
FRONT TONIGHT. LOW-LEVEL JETTING AHEAD OF THE FRONT LOOKS MEAGER
AT BEST...BUT MAY BE ENOUGH TO RAISE WINDS BACK TO 15-20 KT FOR
MOST LEGS. SEAS WILL RESPOND SLIGHTLY...BUT BOTH WINDS AND SEAS
ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS.
SATURDAY THROUGH TUESDAY...SURFACE FLOW WILL STEADILY VEER TO THE
NORTH AND BRIEFLY DIMINISH BEHIND A DESCENDING COLD FRONT
SATURDAY. SURFACE HIGH PRESSURE BUILDING FROM THE NORTH BEHIND THE
FRONT WILL THEN SUPPORT A BRIEF SURGE IN NORTHERLY FLOW ON SUNDAY
THAT COULD APPROACH MARGINAL SMALL CRAFT ADVISORY THRESHOLDS. THE
CENTER OF THE SURFACE HIGH WILL THEN SHIFT OFF THE COAST AND INTO
THE MARINE ZONES MONDAY AND TUESDAY...ALLOWING MODERATE SOUTHERLY
FLOW TO PREVAIL. CONDITIONS APPEARS TO REMAIN BELOW ADVISORY LEVELS
MONDAY AND TUESDAY.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EST THIS MORNING FOR AMZ352-
354.
SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR AMZ374.
&&
$$
ST/79
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
549 AM CST FRI JAN 25 2013
.UPDATE...
THE SNOW ACROSS THE AREA IS COMING TO A RAPID END. LOW LEVEL
FORCING IN THE FORM OF SFC CONVERGENCE AIDED IN SATURATING THE LOW
LEVELS TO PRODUCE -SN WHICH FOR THE MOST PART HAS RANGED FROM A
TRACE TO A DUSTING. SAID LOW LEVEL SFC CONVERGENCE IS MOVING EAST
OF THE MISSISSIPPI AND WILL EXIT THE CWFA IN THE NEXT 2-3 HRS.
THE NEXT CONCERN IS CLOUD TRENDS. CLEARING FROM WEST TO EAST WILL
OCCUR ACROSS THE CWFA STARTING AROUND SUNRISE AND MOST OF THE CWFA
WILL BE CLEAR BY MID MORNING. THE QUESTION IS THE LOW CLOUDS IN
THE DAKOTAS AND MINNESOTA. EXTRAPOLATION OFF SATELLITE AND INPUT
FROM RECENT TRENDS WITH THE RAP MODEL SUGGEST THEY WILL ENTER THE
CWFA BY LATE MORNING.
HOWEVER...DAY TIME HEATING SHOULD ALLOW THE LEADING EDGE TO ERODE
AS SOME MIXING OCCURS.
SO...WILL SPEED UP THE CLEARING TREND DURING THE MORNING HOURS AND
ADD JUST A BIT MORE CLOUDS FOR THE AFTERNOON. AND UPDATE
REFLECTING THESE CHANGES WILL BE AVAILABLE SHORTLY. ..08..
&&
.AVIATION...
THE -SN FOR THE MOST PART IS NOW OVER FOR ALL TAF SITES. SATELLITE
TRENDS INDICATE CONDITIONS BECOMING VFR BY 15Z/25. SATELLITE AND
RAP MODEL TRENDS SUGGEST THE LOW CLOUDS ACROSS THE DAKOTAS AND
MINNESOTA WOULD IMPACT KCID/DBQ/KMLI AFT 18Z/25 WITH MVFR
CONDITIONS. KCID/KMLI ARE MORE QUESTIONABLE AS THE LEADING EDGE OF
THE CLOUDS SHOULD ERODE WITH DAY TIME HEATING. HOWEVER...KDBQ
SHOULD SEE MVFR CONDITIONS DLVPG. VFR CONDITIONS ARE EXPECTED TO
RE-DEVELOP AFT 00Z/26 AT ALL TAF SITES. ..08..
&&
.PREV DISCUSSION... /ISSUED 322 AM CST FRI JAN 25 2013/
SYNOPSIS...
06Z SFC ANALYSIS HAS A WARM FRONT RUNNING FROM THE EASTERN DAKOTAS
INTO WEST TEXAS. A WEAK LOW WAS NEAR KJLN WITH AN INVERTED TROF
RUNNING INTO SOUTHEAST NEBRASKA AND ANOTHER TROF RUNNING INTO
CENTRAL MISSOURI. DEW POINTS WERE IN THE SINGLE DIGITS AND TEENS
ACROSS MUCH OF THE MIDWEST WITH 20S AND HIGHER IN THE SOUTHERN
PLAINS AND DEEP SOUTH.
SHORT TERM...TODAY AND TONIGHT...
IMMEDIATE CONCERN IS THE SNOW POTENTIAL AND AMOUNTS.
BASED ON DATA THROUGH 07Z...THE RAP TRENDS OF 850-700MB CONDENSATION
PRESSURE DEFICITS BELOW 10...F VECTOR CONVERGENCE AND/OR 800-750MB
CONVERGENCE...AND A THETA E GRADIENT SEEMS TO CORRELATE FAIRLY WELL
WITH WHERE SNOW IS REACHING THE GROUND. USING THIS AS A ROUGH GUIDE
THERE SHOULD BE A QUICK SHOT OF LIGHT SNOW MOVE THROUGH THE
NORTHWEST QUADRANT OF THE CWFA IN THE 09-12Z TIME FRAME AND THEN THE
NORTHEAST QUADRANT IN THE 12-15Z TIME FRAME. THE FCST SOUNDINGS FROM
THE GFS LOOK OVERLY MOIST BUT THE WRF AND RAP DO HOLD ON TO A NARROW
LAYER OF DRY AIR TO AROUND SUNRISE. THIS DRY AIR WILL HELP HOLD DOWN
AMOUNTS.
AS FOR AMOUNTS...A TRACE TO A DUSTING WILL BE ABOUT ALL THAT WILL
OCCUR WITH THIS EVENT MAINLY FOR AREAS ALONG/NORTH OF I-80. THE
OVERALL CONVERGENCE WEAKENS WITH TIME AS WELL SO THE SNOW SHOULD
ONLY LAST FOR 2-3 HRS AT ANY GIVEN LOCATION.
BASED ON SATELLITE TRENDS...THERE SHOULD BE A GENERAL CLEARING OF
SKIES DURING THE LATE MORNING AND AFTERNOON HOURS. LOW LEVEL LAPSE
RATES DO GET RELATIVELY STEEP ACROSS THE FAR NORTHEAST PARTS OF THE
CWFA THAT MAY ALLOW SOME FLURRIES TO DEVELOP DURING THE AFTERNOON.
TONIGHT...ANOTHER HIGH PRESSURE BUILDS INTO THE AREA RESULTING IN
QUIET BUT DRY CONDITIONS. ..08..
LONG TERM...SATURDAY THROUGH NEXT THURSDAY...
SATURDAY WILL BE RELATIVELY QUIET WITH WARM AIR ADVECTION GOING ON
OVERHEAD FOR GRADUALLY WARMING TEMPERATURES. HIGHS SHOULD BE IN THE
20S TO NEARLY 30.
SATURDAY NIGHT THROUGH MONDAY TO BE THE MAIN CONCERN OF THE SHIFT.
THE UPPER LEVEL PATTERN HAS SHIFTED TO A BROAD RIDGE OVER THE
MIDWEST BY SATURDAY NIGHT AND SUNDAY...WITH A SHARP UPPER LEVEL
TROUGH MOVING ONTO THE WEST COAST. A SHORTWAVE EJECTS OUT OF A MORE
SOUTHERN STREAM TROUGH...AND MOVES ACROSS THE MIDWEST THROUGH THE
WEAKENING UPPER LEVEL RIDGE AXIS. THIS PRODUCES CYCLOGENESIS OVER
NORTHEAST COLORADO ON SUNDAY. THE STRONG WARM AIR ADVECTION AHEAD
OF THIS BRINGS 850MB TEMPERATURES OVER THE FORECAST AREA ABOVE
FREEZING FOR MUCH OF SATURDAY NIGHT AND SUNDAY...JUST AS A NICE SLUG
OF MOISTURE COMES INTO THE AREA FROM THE GULF...JUST AS THE
SHORTWAVE MOVES ACROSS THE FORECAST AREA. THIS IS LIKELY TO PRODUCE
A NICE WAVE OF WARM AIR ADVECTION OVER THE AREA STARTING LATE
SATURDAY NIGHT AND CONTINUING THROUGH SUNDAY AND INTO MONDAY.
HOWEVER...THE WARM AIR ADVECTION ALOFT IS GOING TO WARM ABOVE
FREEZING BEFORE WE DO AT THE SURFACE. AN ISSUE OF LOW CONFIDENCE IN
THIS FORECAST IS HOW COLD WE WILL BE ONCE THE PRECIPITATION MOVES
INTO THE AREA...AND HOW QUICKLY TEMPERATURES WARM ON SUNDAY. THE
NAM IS OF LITTLE HELP...AS IT HAS ALREADY INITIALIZED WITH 2-4
INCHES OF SNOW COVER ON THE GROUND OVER MUCH OF IOWA...WHICH DOES
NOT EXIST. THIS IS GOING TO CONTAMINATE HOW QUICKLY IT WILL WARM
TEMPERATURES ON SUNDAY. THE GFS SHOULD HAVE A SIMILAR
INITIALIZATION. THE CANADIAN GEM IS BETTER. HOWEVER...NO MATTER
THE SOLUTION IT APPEARS THAT WE ARE LOOKING AT AT LEAST A SHORT
PERIOD OF FREEZING RAIN BEFORE TEMPERATURES WARM ABOVE FREEZING ON
SUNDAY. IT IS A VERY TOUGH FORECAST...AND HOPEFULLY MODEL CHANGES
BETWEEN NOW AND THEN WILL REMOVE THE SPECTER OF THE ICING FROM
FREEZING RAIN. SUNDAY NIGHT AND MONDAY ALL THE PRECIPITATION
GRADUALLY SHIFTS TO ALL RAIN AS TEMPERATURES CONTINUE TO WARM. THE
SURFACE TROUGH AXIS GRADUALLY SHIFTS EAST OF THE AREA AND ALLOWS
COLD AIR TO MOVE BACK INTO THE AREA BY TUESDAY...AND RAIN SHOULD
CHANGE BACK TO SNOW BEFORE THIS EVENT ENDS TUESDAY AFTERNOON AND
NIGHT.
WEDNESDAY AND THURSDAY ANOTHER COLD FRONT MOVES THROUGH THE FORECAST
AREA...AND BRINGS ANOTHER SHOT OF ARCTIC AIR INTO THE FORECAST AREA
BY THURSDAY. HIGH TEMPERATURES SHOULD BE BACK INTO THE TEENS AND
20S BY THURSDAY.
LE
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
601 AM EST FRI JAN 25 2013
.AVIATION...
//DISCUSSION...
LOW PRESSURE SYSTEM TRACKING THROUGH THE NORTHERN GREAT LAKES WILL
ALLOW AN AREA OF SNOWFALL TO OVERSPREAD SOUTHEAST MICHIGAN TODAY.
POCKETS OF LIGHT SNOW WILL BEGIN TO EMERGE THIS MORNING AS THE LOWER
LAYERS GRADUALLY SATURATE. CONDITIONS WILL LOWER TO IFR/MVFR
16Z-20Z AS SNOWFALL INCREASES IN COVERAGE AND INTENSITY. MVFR
CONDITIONS WILL LINGER INTO THE EVENING AS LIGHT SNOW SHOWERS
CONTINUE ACROSS SOUTHEAST MICHIGAN. SNOWFALL AMOUNTS IN THE 1 TO 2
INCH RANGE ARE EXPECTED FROM THIS SYSTEM.
FOR DTW...A BRIEF BURST OF LIGHT SNOW REMAINS POSSIBLE THIS
MORNING...BUT UPSTREAM TRENDS SUGGEST THE GREATER POTENTIAL WILL
EXIST AROUND MIDDAY /16-20Z/.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN CEILINGS BELOW 5000 FEET THIS MORNING...HIGH
CONFIDENCE THIS AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 342 AM EST FRI JAN 25 2013
SHORT TERM...TODAY AND TONIGHT
AN APPROACHING CLIPPER SYSTEM WILL BRING ACCUMULATING SNOW TO
SOUTHEAST MICHIGAN TODAY AND TONIGHT. THE MAIN QUESTION REMAINS HOW
MUCH SNOW WILL FALL FROM THIS SYSTEM AS IT TRACKS THROUGH THE
CENTRAL GREAT LAKES. REGIONAL 00Z RAOB SOUNDINGS FROM KDTX/KAPX/KGRB
SHOW A VERY DRY AIRMASS BETWEEN 700 AND 500 MB WHICH NEEDS TO BE
OVERCOME BEFORE SNOWFALL CAN BEGIN IN EARNEST ACROSS SOUTHEAST
MICHIGAN. THE AMOUNT OF DRY AIR IS CONCERNING WITH RELATIVE HUMIDITY
VALUES FALLING TO AROUND 10 PERCENT IN THIS LAYER. HOWEVER AS KGRB
HAS PROVED THIS LAYER CAN BE OVERCOME AS NORTHEAST WISCONSIN IS
CURRENTLY GETTING ACCUMULATING SNOWFALL. WHILE THIS DRY AIR MAY NOT
PREVENT THE INEVITABLE...IT WILL PROBABLY DELAY THE ONSET OF THE
SNOWFALL WHICH THE NAM AND HRRR MODEL DEPICT RATHER WELL THIS RUN.
WHAT THIS SYSTEM LACKS IN MOISTURE IT MAKES UP FOR IN FORCING WITH
UPPER LEVEL DIVERGENCE IN THE LEFT EXIT REGION OF A STRONG 130 KNOT
JET DIVING SOUTH OVER THE SOUTHERN GREAT LAKES AND A STRONG MID
LEVEL SHORTWAVE CLEARLY EVIDENT ON WATER VAPOR IMAGERY CURRENTLY
SITUATED OVER THE UPPER MISSISSIPPI VALLEY. WHILE THESE DYNAMICS
WILL NOT MAKE UP FOR THE LACK OF MOISTURE...THEY WILL BE ABLE TO
TAKE ADVANTAGE OF THE MEAGER MOISTURE IN PLACE WITH AN ADDED BOOST
FROM LOW WATER CONTENT SNOW AS SNOW RATIOS OF 18 TO 19 TO 1 ARE
EXPECTED. WITH DRIER MODEL SOLUTIONS YIELDING QPF IN THE 0.05 TO
0.10 RANGE SNOWFALL AMOUNTS IN THE 1 TO 2 INCH RANGE SEEM REASONABLE
FROM THIS SYSTEM DURING THE TIME OF BEST FORCING BETWEEN 12Z AND 18Z.
THE HEADLINE QUESTION NEEDS TO BE ADDRESSED GIVEN THE BULK OF THE
SNOW IS EXPECTED IN A SHORT WINDOW OF A FEW HOURS WITH COLD SURFACE
TEMPERATURES IN THE SINGLE DIGITS UP TO THE MIDDLE TEENS EXPECTED TO
RENDER REGULAR ROAD SALT VERY INEFFICIENT FOR MELTING SNOW AND ICE
DURING THE MORNING HOURS. DESPITE THESE FACTORS THE DELAYED ONSET OF
THE SNOW WILL BE HELPFUL IN LIMITING THE EFFECT OF THESE CONDITIONS
ON THE MORNING COMMUTE. IN ADDITION UPSTREAM OBSERVATIONS ACROSS
WISCONSIN ARE NOT THAT IMPRESSIVE WITH VISIBILITIES GENERALLY AT OR
ABOVE 1 MILE. WITH THIS IN MIND PLAN TO HANDLE THE SNOW WITH SPECIAL
WEATHER STATEMENTS AS IT TRACKS EAST AND FORGO HEADLINES GIVEN MOST
OF THE IMPACT WILL BE AFTER THE MORNING COMMUTE.
ALTHOUGH THE MAIN FORCING FROM THE SYSTEM WILL BE EAST DURING THE
LATE AFTERNOON HOURS THE LOW ITSELF AND COLD FRONT WILL NOT MOVE
THROUGH UNTIL THE EVENING HOURS. THIS WILL MEAN LIGHT SNOW SHOWERS
WILL CONTINUE THROUGH THE OVERNIGHT HOURS...HOWEVER WITH THE BEST
FORCING AND MOISTURE OFF TO THE EAST ONLY A DUSTING OF ADDITIONAL
ACCUMULATION IS EXPECTED AFTER 18Z.
CLOUD COVER IS EXPECTED FOR MUCH OF THE DAYTIME HOURS...LIMITING
INCOMING SOLAR RADIATION. DESPITE SOUTHERLY SURFACE WINDS AHEAD OF
THE LOW...THE AIRMASS TO THE SOUTH IS NOT MUCH WARMER THAN THE ONE
CURRENTLY IN PLACE...OFFERING LITTLE TO NO WARM AIR ADVECTION TO
BOOST SURFACE TEMPERATURES. THEREFORE HIGHS ARE EXPECTED TO BE
IN THE LOW TO MID 20S THIS AFTERNOON. CONTINUED CLOUD COVER
OVERNIGHT AND NOT MUCH COLD AIR ADVECTION BEHIND THE COLD FRONT WILL
MEAN OVERNIGHT LOWS WILL GENERALLY BE IN THE 10 TO 15 DEGREE RANGE.
LONG TERM...SATURDAY THROUGH THURSDAY
BRIEF PERIOD OF DEEPER NORTHWEST FLOW TAKES HOLD ON SATURDAY IN THE
WAKE OF THE EXITING CLIPPER SYSTEM AND ALONG THE FRONT FACE OF THE
EXPANDING LOW TO MID LEVEL ANTICYLONIC FLOW FILLING ACROSS THE UPPER
MS VALLEY. SHEAR AXIS EMBEDDED WITHIN THE WEAKENING CYCLONIC FLOW
WILL REMAIN DRAPED ACROSS THE REGION DURING THIS TIME. THIS BROAD
ASCENT WORKING INTO A DEEPENING CONVECTIVE LAYER AND A MOIST LAYER
THAT REMAINS FAVORABLY SATURATED WITH RESPECT TO ICE /-10 TO -14C
ISOTHERM/ WILL SUPPORT SOME VERY LIGHT SNOW SHOWER/FLURRY PRODUCTION
DURING THE DAY. IN ADDITION...BANDS OF LAKE DRIVEN SNOWFALL
ANCHORED ON THE LAKE HURON AGGREGATE TROUGH AXIS WILL TEND TO SHIFT
SOUTH-SOUTHEAST DOWN THE LONG FETCH IN RESPONSE TO INCREASING
PRESSURE AND A VEERING NORTHERLY WIND EMERGING ACROSS NORTHERN
PORTIONS OF THE LAKE. THE POTENTIAL DOES EXIST FOR THE WESTERN
PERIPHERY OF THIS BAND TO SWEEP ACROSS THE EASTERN THUMB SATURDAY
MORNING...BRINGING A QUICK SHOT OF ACCUMULATING SNOW. DRYING
NORTHERLY FLOW AND THE LOSS OF THE DIURNAL HEATING CYCLE WILL
SCATTER ANY LINGERING STRATOCU SATURDAY EVENING. HIGH CLOUDS WELL
IN ADVANCE OF THE NEXT SYSTEM MAY BE PROBLEMATIC FOR MAXIMIZING AN
OTHERWISE IDEAL SETUP FOR TEMPERATURES TO REALLY PLUMMET
/DIMINISHING GRADIENT...SNOW COVERAGE GROUND/. COLDEST LOCALES
CERTAINLY CAN MAKE A RUN TOWARD THE LOWER SINGLE DIGITS SUNDAY
MORNING GIVEN THE STRENGTH OF THE RESIDENT AIRMASS.
MID LEVEL CIRCULATION CURRENTLY ANCHORED OFF THE SOUTHERN CA
COASTLINE WILL RECEIVE THE NECESSARY NUDGE EASTWARD OVER THE WEEKEND
AS STRONG MID LEVEL ENERGY CRASHING INTO THE WEST COAST CARVES OUT
A DEEP LONG WAVE TROUGH. SHEARED WAVE EXPECTED TO EMBED WITHIN AN
INCREASING WEST-SOUTHWEST UPPER HEIGHT FIELD DOWNSTREAM...
TRANSLATING ACROSS SE MICHIGAN SUNDAY NIGHT. THIS PROCESS WILL
OCCUR COINCIDENT TO AND LIKELY ENHANCES A CORRIDOR OF WARM AIR
ADVECTION AND MOIST ISENTROPIC ASCENT THAT EMERGES IN INCREASING LOW
LEVEL SOUTHERLY FLOW. STRONG MODEL SUPPORT EXISTS IN DRIVING THIS
FORCING FIELD AND THE ATTENDANT MOISTURE PLUME NORTHEAST AND ACROSS
SE MICHIGAN SUNDAY NIGHT AND EARLY MONDAY. NORTHERN PORTIONS OF THE
FORECAST AREA MAY RECEIVE JUST A GLANCING SHOT OF PRECIPITATION...
WITH SOME SUGGESTION THAT THE BETTER MOISTURE TRANSPORT VECTOR
ANCHORED ON AN ATTENDANT LOW LEVEL JET CORE WILL FOCUS ACROSS THE
NORTHERN OHIO VALLEY. A WARMING THERMAL PROFILE WILL INTRODUCE
PTYPE CONCERNS DURING THE LATTER HALF OF THIS PERIOD
/MONDAY MORNING/...BUT WET BULB TEMPERATURES SECURELY BELOW FREEZING
AT ONSET WILL SUPPORT A PERIOD OF SNOWFALL OVERNIGHT. GOOD MOISTURE
QUALITY (PROGGED PW OF .75"...SPECIFIC HUMIDITY APPROACHING 3 G/KG)
INTO THE BACKGROUND FORCING INDICATES THAT THE PROGGED .2-.3" OF QPF
ACROSS THE SOUTH IS ATTAINABLE.
LOW LEVEL THERMAL RIDGE CARRYING 850 MB TEMPERATURES IN THE 6-8C
RANGE WILL SETTLE OVERHEAD IN THE WAKE OF THE EARLY DAY WARM FRONTAL
PASSAGE ON MONDAY. MID LEVEL MOISTURE STRIPS EAST BUT PLENTIFUL LOW
LEVEL MOISTURE AIDED BY THE SNOWMELT MAY PROMOTE A PERIOD OF
FOG/DRIZZLE. THIS WILL WARRANT JUST A CONSERVATIVE ADJUSTMENT
UPWARD IN HIGHS MONDAY DESPITE THE STRENGTHENING SOUTHWEST
GRADIENT/ADVECTIVE PROCESS. HIGHS INCHING TOWARD THE LOWER 40S
SOUTH. MODEL CONSENSUS PROVIDING A MORE PROGRESSIVE OUTLOOK WITH
THE EASTWARD TRANSLATION OF THE MEAN WESTERN CONUS TROUGH EARLY NEXT
WEEK...PERHAPS OWING TO THE PRESENCE OF A CONSIDERABLY FLATTER/LESS
AMPLIFIED FLOW DOWNSTREAM. THIS TRANSLATES INTO A FASTER ATTENDANT
LEAD FRONTAL PASSAGE SOMETIME ON TUESDAY...PROVIDING SOME DOUBT AS
TO THE DEGREE OF THE PRE-FRONTAL WARMUP. THIS FIRST ROUND OF COLD
AIR ADVECTION NOTHING EXTRAORDINARY...LIKELY SIMPLY EASING
TEMPERATURES BACK TO LATE JANUARY STANDARDS. THE NEXT ARCTIC PUSH
WILL BE TIED TO THE MORE PRONOUNCED TRAILING HEIGHT FALL REGION
PIVOTING THROUGH THE MEAN TROUGH...ARRIVING FOR THE END OF NEXT
WEEK.
MARINE...
AN ALBERTA CLIPPER SYSTEM WILL TRACK THROUGH THE GREAT LAKES REGION
TODAY AND TONIGHT. LIGHT SOUTHERLY WINDS TODAY WILL KEEP WAVE
HEIGHTS LOW THROUGH THE DAY. WINDS BEGIN TO INCREASE WITH GUSTS IN
THE 15 TO 20 KNOT RANGE AND EVENTUALLY SHIFTING TO THE
WEST-NORTHWEST ON SATURDAY BEHIND THE DEPARTING LOW. AT THIS TIME
NOT EXPECTING WAVES TO REACH SMALL CRAFT ADVISORY CRITERIA DURING
THE SATURDAY TIMEFRAME. WINDS EASE CONSIDERABLY SATURDAY NIGHT AS
HIGH PRESSURE TRACKS THROUGH THE REGION BEFORE PICKING UP SLIGHTLY
AND TURNING SOUTHERLY ON SUNDAY AS THE HIGH MOVES OFF TO THE EAST.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....99
SHORT TERM...KURIMSKI
LONG TERM....MR
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
438 AM CST FRI JAN 25 2013
.DISCUSSION...
TODAY AND TONIGHT...WEAK CLIPPER-TYPE LOW OVER NRN MN THIS MRNG
WILL SHIFT E ACROSS THE GREAT LAKES THROUGH TNGT...DRAGGING A
CDFNT ACROSS MN AND WI. EARLY MRNG LGT SNOW OVER ERN PORTIONS OF
THE MPX CWFA HAVE QUICKLY DISSIPATE...OWING TO MUCH DRIER AIR
BEING ADVECTED INTO THE REGION IN ADVANCE OF THE CDFNT. AS THE LOW
PRES CENTER SHIFTS AWAY...SKIES WILL PARTIALLY CLEAR OUT BUT
LITTLE TO NO WARMING IS EXPECTED WITH THE ADDITIONAL SUNSHINE DUE
TO THE SFC FROPA. TEMPS WILL REMAIN FAIRLY STNRY DURG THE DAY TDA
THEN DECRS RAPIDLY LATE DAY THRU THE EVENING AS ANOTHER ARCTIC
HIGH PRES AIRMASS MOVES INTO THE REGION. HIGHS TDA THAT GENERALLY
REACH THE TEENS WILL DROP TO THE SINGLE DIGITS BELOW ZERO TNGT FOR
LOWS. HAVE BEEN ABLE TO CANCEL THE WINTER WX ADVY THIS MRNG SINCE
ANY ADDITIONAL SNOW ACCUM WILL BE AN INCH OR LESS...AND WILL NOT
NEED A WIND CHILL ADVY TNGT SINCE WINDS WILL DROP OFF AS THE
INCOMING AREA OF HIGH PRES CENTERS ITSELF OVER THE AREA. THAT
SAID...WIND CHILL VALUES WILL STILL LIKELY DROP TO BETWEEN -10 AND
-20 OVERNIGHT.
SATURDAY THROUGH MONDAY...THE AREA OF SFC HIGH PRES WILL QUICKLY
EXIT TO THE E SAT BUT WILL BE FOLLOWED BY A LARGE SCALE UPPER
LEVEL RIDGE AXIS THAT WILL CROSS THE REGION SAT INTO SUN. THE SLY
FLOW ON THE BACKSIDE OF THE HIGH COMBINED WITH MUCH ELEVATED H5
HEIGHTS THRU THE WEEKEND INTO EARLY NEXT WEEK TRANSLATE INTO A
NOTICEABLE WARMING TREND OVER THE WEEKEND INTO NEXT WEEK. HIGHS
WILL REACH THE UPR 20S TO LWR 30S ON SUN FOLLOWED BY LOW-MID 30S
ON MON. THE COMPLICATING FACTOR IS THAT A PAIR OF WEAK LOW PRES
SYSTEMS...ONE TO THE S AND ONE TO THE N...WILL MOVE WITHIN CLOSE
PROXIMITY OF THE MPX CWFA TO PRODUCE ISOLD TO SCTD AREAS OF PRECIP
AND IT IS NOT WELL-DEFINED WHAT THE P-TYPES WILL BE FOR THE ENTIRE
TIME. DURING THE TIMES THAT SFC TEMPS APCH THE FREEZING MARK...
MODEL SOUNDINGS AND SREF PROGS INDICATE A STRONG POSSIBILITY OF
FZRA RATHER THAN IP OR A RAIN/SNOW MIX SO HAVE INCLUDED MENTION OF
FZRA FOR A FEW PERIODS THRU THE WEEKEND. IN ADDITION...THE
WEAKENED STRENGTH OF THE LOW PRES SYSTEMS WILL FORCE POPS NO
HIGHER THAN MID-CHC RANGE THROUGH THIS PERIOD OF THE FCST.
TUESDAY THROUGH THURSDAY...BY TUE...THE OVERALL UPPER LEVEL
PATTERN CHANGES FROM A RIDGE OVER THE CENTRAL CONUS TO A
DEVELOPING TROF OVER THE WRN CONUS THAT WILL SHIFT E THROUGH
MIDWEEK. THIS WILL ALLOW FOR AN ELONGATED LOW PRES AREA FROM THE
SRN GREAT LAKES TO THE TX/OK PANHANDLE TO GRADUALLY SHIFT E. MOST
OF THE FOCUS FOR PRECIP WILL BE ON THE SRN AND ERN PORTIONS OF THE
CWFA FOR TUE. AS THIS COMPLEX SYSTEM MOVES OUT WED INTO THU...THE
CENTRAL TROUGH AXIS WILL SWING THRU THE CENTRAL CONUS...OPENING
THE DOOR TO NW FLOW THAT WILL BRING DOWN ANOTHER ARCTIC HIGH PRES
AIRMASS FOR WED INTO THU. THIS WILL DROP HIGH TEMPS FROM THE 20S-
30S ON TUE BACK DOWN TO THE SINGLE DIGITS ON WED-THU. IN TURN...
LOW TEMPS WILL DROP TO THE 5 TO 15 DEGREES BELOW ZERO RANGE.
&&
.AVIATION.../06Z TAF ISSUANCE/
DRY AIR IS BEATING OUT THE SNOWFALL...AND CONFIDENCE IN IT
OCCURRING AT ANY OF THE TERMINALS IS CLOSE TO NIL. PROBLEM HAS
BEEN A DISCONNECT BETWEEN MID/UPPER LEVEL MOISTURE AND LOW LEVEL
MOISTURE. NAMELY...AS THE LATER FINALLY SHOWS UP...THE FORMER
DEPARTS AS A DRY SLOT MOVES OVERHEAD. BEST CHANCE FOR SNOW WHEN
LOOKING AT THE RAP WOULD BE EAU...BUT EVEN HERE ONLY EXPECT A
DUSTING...WITH MVFR VIS RESTRICTIONS AT WORST. FOR CIGS...MVFR
CIGS HAVE BEEN CONFINED CLOSER TO THE SFC LOW...WHICH AT 6Z WAS
OVER NE NODAK AND WILL BE OVER NRN WI BY 15Z. LOW CIGS SHOULD BE
CONFINED CLOSER TO THE LOW AND WILL LIKELY PUT NRN TERMINALS ON
SRN EDGE OF MVFR CIGS DURING THE DAY FRIDAY. CLEARING MOVING IN
QUICKLY ACROSS NORTH CENTRAL NODAK ALSO LEADING TO LESS CONFIDENCE
ON WHAT WILL HAPPEN WITH CIGS TOMORROW. WHERE THERE STILL IS HIGH
CONFIDENCE IS WITH GUSTY NW WINDS FRIDAY. CAA DURING THE AFTERNOON
WILL PROMOTE STEEP LAPSE RATES AND EFFICIENT MIXING OF WINDS DOWN
FROM 3K FT...WHICH SHOULD PROMOTE NW GUSTS TO 35 KTS IN WRN MN
DURING THE LATE MORNING AND TO 30 KTS ACROSS ERN MN AND WRN WI IN
THE EARLY AFTERNOON. AFTER 00Z...SKIES WILL BE QUICKLY CLEARING
OUT AND WINDS CALMING DOWN.
KMSP...HAVE REMOVED SNOW MENTION FROM THE TAF...THOUGH A FEW
FLURRIES CAN NOT BE RULED OUT THROUGH 8Z...BUT DO NOT ANTICIPATE
AND VIS RESTRICTIONS. CIGS DO NOT LOOK TO LOWER TO MVFR LEVELS
UNTIL AROUND 12Z AS CIGS CURRENTLY UP BY FARGO MOVE INTO THE TWIN
CITIES. LOTS OF UNCERTAINTY WITH HOW LONG RESTRICTED CIGS WILL
HANG AROUND...BUT ENHANCED MIXING WITH BARE GROUND MAY SUPPORT A
MORE ROBUST POST FRONTAL STRATO CU FIELD THAN AREAS TO THE
N/W...KEEPING MVFR CIGS IN PLACE THROUGH THE AFTERNOON. WITH
WINDS...TRANSITION TO THE NW WILL HAPPEN DURING THE MORNING
RUSH...MAKING THE TRANSITION OF AIRPORT OPERATIONS FROM THE 15S
TO THE 30S TRICKY. SEEING PLENTY OF GUST POTENTIAL FOR TOMORROW
AND MAY SEE A GUST OR TWO APPROACH 35 KTS AROUND 18Z AS INITIAL
SURGE OF COLD AIR MOVES IN.
/OUTLOOK FOR KMSP/
SAT...VFR. SE WINDS AT 5-10 KTS.
SUN...MVFR WITH IFR AND -SN/FZRA/RA POSSIBLE. WINDS SE 10 KTS.
MON...MVFR/IFR CIGS POSSIBLE. WINDS SE 4-8 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
JPC/BORGHOFF
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
535 AM CST FRI JAN 25 2013
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
325 AM CST FRI JAN 25 2013
MAIN FORECAST CONCERNS ARE ON SNOW AND WIND POTENTIAL TODAY...THEN
IF PRECIPITATION CAN OCCUR AND WHAT TYPE FOR SUNDAY INTO SUNDAY
NIGHT.
CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A POTENT TROUGH OFF THE PACIFIC NORTHWEST COAST...RIDGING
OVER THE NORTHERN U.S. ROCKIES INTO ALBERTA...A SHORTWAVE TROUGH
DIGGING INTO NORTHWEST MINNESOTA...AND A SHORTWAVE OVER SOUTHEAST
MINNESOTA. AHEAD OF THIS LATTER SHORTWAVE...WATER VAPOR...IR IMAGERY
AND SURFACE OBSERVATIONS SHOWED A LARGE EXPANSE OF MID AND HIGH
CLOUDS. RAP TROPOPAUSE ANALYSIS ALSO HAD A BROAD 120-140KT JET FROM
NEBRASKA TO OHIO DOWNSTREAM OF THE SHORTWAVE...ACTUALLY PLACING THE
FORECAST AREA IN THE SUBSIDENT LEFT ENTRANCE REGION. 00Z SOUNDINGS
FROM MPX...GRB AND DVN SHOWED A GREAT DEAL OF DRY AIR BELOW
700MB...WITH DEWPOINT DEPRESSIONS AS MUCH AS 30C. THIS DRY AIR HAS
BEEN EFFECTIVE AT MINIMIZING SNOWFALL OUT OF THE MID/HIGH CLOUDS
FROM REACHING THE SURFACE. THERE WAS HIGHER LOWER LEVEL MOISTURE OFF
TO THE WEST AT ABR AND OAX...NOTED BY ITS 00Z SOUNDING HAVING 850MB
DEWPOINT DEPRESSION BETWEEN 1-5C. THIS HAS BEEN SLOWLY ADVECTING
TOWARDS THE AREA REFLECTED BY SOUTHWEST 25-40KT WINDS ON PROFILER
AND VWP DATA. BETWEEN 06-08Z...SOME SNOW FINALLY GOT GOING...BUT THE
BACK EDGE BEHIND THE LEAD SHORTWAVE WAS RAPIDLY PUSHING EAST...WITH
KRST AND KCCY NOW DRY. TO THE NORTH...A BAND OF WARM ADVECTION SNOW
HAS BEEN ONGOING FROM NORTHERN MN INTO NORTHERN WI...DOWNSTREAM OF
THE NORTHWEST MN SHORTWAVE TROUGH. IN THE WAKE OF THIS SHORTWAVE
TROUGH...ANOTHER SURGE OF ARCTIC AIR WAS NOTED WITH TEMPERATURES IN
THE TEENS AND 20S BELOW ZERO OVER CENTRAL SASKATCHEWAN. THE COLD AIR
WAS IN THE WAKE OF A 1012MB SURFACE LOW IN NORTHWEST MN.
TODAY AND TONIGHT...MODELS ARE IN GOOD AGREEMENT DROPPING THE
SHORTWAVE TROUGH OVER NORTHWEST MINNESOTA ACROSS CENTRAL WISCONSIN
BY 18Z...THEN INTO SOUTHEAST LOWER MI BY 00Z. 500MB HEIGHTS SLOWLY
RISE THEREAFTER AS THE NORTHERN ROCKIES RIDGE SLIDES EASTWARD...
PLACING THE FORECAST AREA IN AN INFLECTION POINT BETWEEN A TROUGH
AND RIDGE AXIS BY 12Z SATURDAY. THE TROPOPAUSE DROPS NICELY THIS
MORNING WITH THE SHORTWAVE TROUGH MOVING IN...AS MUCH AS 100MB TO
NEAR 350MB ACROSS MUCH OF WISCONSIN BY 15Z. ALTHOUGH THIS IS GOOD
DYNAMIC FORCING...THE SCOURING OUT OF MID AND UPPER LEVEL MOISTURE
BY THE LEAD SHORTWAVE AHEAD OF THE TROUGH IS VERY PROBLEMATIC. AS
SUCH...MODELS HAVE BACKED OFF ON THE AMOUNT OF PRECIPITATION WITH
THE WARM ADVECTION AND DPVA AHEAD OF THE SYSTEM. THIS MATCHES TOO
WITH RADAR TRENDS...AND THUS HAVE SHORTENED THE END TIME OF THE
ADVISORY TO 12Z. IN FACT...WE MAY HAVE TO WAIT UNTIL THE
AFTERNOON...WHEN SNOW ACTUALLY LOOKS BETTER IN THE WAKE OF THE
SHORTWAVE TROUGH AND SURFACE LOW. THIS IS DUE TO COLD ADVECTION
COMBINING WITH LINGERING SURFACE MOISTURE TO PRODUCE CONVECTIVE
SNOW. THE 25.00Z NAM AND HIRES NMM RUNS ARE THE MOST BULLISH WITH
THE CONVECTIVE IDEA...WHILE ARW MODELS ARE NOT. IT APPEARS THE NMM
CORE MAY BE MOISTENING SURFACE DEWPOINTS UP TOO MUCH. TOOK A
COMPROMISE APPROACH WHICH RESULTS IN FLURRIES ALONG THE MS RIVER AND
SCATTERED SNOW SHOWERS NORTH OF I-94 WHERE THE BEST LOW LEVEL
INSTABILITY IS PRESENT. IN ADDITION TO THE SNOW...SETUP FOR THE
AFTERNOON IS FAVORABLE FOR WINDY CONDITIONS. THE COMBINATION OF COLD
ADVECTION...A TIGHT PRESSURE GRADIENT IN THE WAKE OF THE LOW...BEING
AT PEAK HEATING AND MIXING DEPTHS UP TO 875-900MB SHOULD YIELD GUSTS
IN THE 25-30 KT RANGE. EXPECT THE SNOW TO QUICKLY DIMINISH THIS
EVENING WITH LOSS OF HEATING AND THE SHORTWAVE TROUGH SHIFTING OFF.
WINDS LOOK TO TAKE SOME TIME DIMINISHING SINCE THE HIGH PRESSURE
AREA DOES NOT BUILD IN UNTIL LATE IN THE NIGHT...I.E. AT THE TIME OF
THE INFLECTION POINT IN THE FLOW AT 500MB. THE COMBINATION OF WIND
AND MUCH OF THE AREA STILL WITH NEAR BARE GROUND WILL KEEP LOWS
WARMER...ESPECIALLY COMPARED TO THE NAM WHICH HAS 5 INCHES ON THE
GROUND ACROSS THE FORECAST AREA. LEANED CLOSER TO THE ECMWF AND MAV
GUIDANCE FOR LOWS.
SATURDAY AND SATURDAY NIGHT...THE UPPER RIDGING OVER THE NORTHERN
ROCKIES IS PROGGED TO CONTINUE MARCHING EAST TOWARDS THE FORECAST
AREA DURING THIS TIME PERIOD...PUSHED ALONG BY TROUGHING OFF THE
PACIFIC NORTHWEST MOVING INLAND AS WELL AS AN UPPER LOW OFF THE
SOUTHERN CALIFORNIA COAST LIFTING INTO SOUTHEAST COLORADO. THE SHIFT
EAST OF THE UPPER RIDGE AXIS...REACHING EASTERN MN BY 12Z
SUNDAY...WILL SETUP A LOW LEVEL RETURN FLOW OVER THE FORECAST AREA
FOR THE AFTERNOON AND NIGHT. AN INCREASE OF MID/HIGH CLOUDS IS
LIKELY GIVEN THE WARM ADVECTION PATTERN...NOTED TOO BY 925MB TEMPS
CLIMBING FROM AROUND -12C AT 12Z SATURDAY TO -2 TO -6C BY 12Z
SUNDAY. THE QUESTION MARK IS LATE SATURDAY NIGHT...IF THE LOW LEVEL
MOISTURE WILL BE DEEP ENOUGH TO RESULT IN PRECIPITATION. THE 25.00Z
NAM/CANADIAN SUGGESTS THIS WOULD OCCUR FROM THE KANSAS CITY AREA
INTO NORTHEAST IOWA. COMPARED TO THE 25.00Z GFS/ECMWF/UKMET... THIS
SEEMS A LITTLE TOO FAR NORTH / FAST. THE OTHER MODEL GROUP KEEPS THE
BULK OF THE WARM ADVECTION PRECIPITATION SOUTH OF I-80. THUS...HAVE
KEPT THE ENTIRE PERIOD FROM 12Z SATURDAY TO 12Z SUNDAY DRY. WITH THE
WARMING 925MB TEMPS AND SOME SUN...HIGHS SHOULD BOUNCE BACK INTO THE
TEENS FOR SATURDAY. WARM ADVECTION PERSISTING THROUGH THE NIGHT PLUS
CLOUDS AROUND WILL LEAD TO RISING TEMPERATURES SATURDAY NIGHT.
SUNDAY AND SUNDAY NIGHT...THIS PERIOD REMAINS VERY PROBLEMATIC AND
UNCERTAIN. THE MAIN PROBLEM IS THE STRENGTH AND SPEED OF THE UPPER
LOW OFF THE SOUTHERN CALIFORNIA COAST LIFTING UP TOWARDS THE AREA ON
SUNDAY. THE SPREAD RANGES FROM:
1. A RELATIVELY STRONG 25.00Z GFS/CANADIAN...STILL SHOWING AT LEAST
A POTENT SHORTWAVE COMING THROUGH THE FORECAST AREA AROUND 06Z
MONDAY.
2. A REALLY WEAK 24.12Z/25.00Z ECMWF WHICH SHEAR THE UPPER LOW APART
AND HAVE ITS REMNANTS TRACK ALONG I-80.
THE 25.00Z NAM/UKMET LIE IN-BETWEEN THESE SCENARIOS. THE DIFFERENCES
NOT ONLY IMPACT WHETHER IT WILL PRECIPITATE...BUT ALSO WHAT TYPE
WOULD OCCUR IF IT DOES PRECIPITATE. THE ECMWF...BEING THE
WEAKEST...LIMITS THE AMOUNT OF MOISTURE RETURN INTO THE FORECAST
AREA FROM THE GULF OF MEXICO...AND NET RESULT IS A DRY FORECAST. THE
GFS/CANADIAN HAVE A MUCH STRONGER LOW LEVEL JET BECAUSE OF A STRONG
SHORTWAVE...THUS SPREAD PRECIPITATION OVER THE ENTIRE AREA. THIS
LATTER SCENARIO WOULD ALSO YIELD A SNOW TO SLEET TO FREEZING RAIN
SITUATION. ONCE THE SHORTWAVE GOES BY...THE PRECIPITATION DIMINISH.
SINCE ALL SCENARIOS SEEM PLAUSIBLE GIVEN THE MODELS HAVE MAINTAINED
GOOD CONTINUITY...HAVE COMPROMISED. THIS RESULTS IN A SLIGHT
LOWERING OF PRECIPITATION CHANCES FOR SUNDAY WHILE SUNDAY NIGHT WAS
PRETTY SIMILAR. FOR PRECIPITATION TYPE...BOTH SNOW AND FREEZING RAIN
SEEM EQUALLY LIKELY TO OCCUR...SINCE THERE ARE ALSO ISSUES WITH ICE
IN THE CLOUDS. HOPEFULLY MODELS WILL COME TOGETHER SOON. THE
TEMPERATURE FORECAST IS ALSO A COMPROMISE...BUT DECENT AGREEMENT
EXISTS THAT READINGS SHOULD GET UP CLOSE TO FREEZING ON
SUNDAY...THEN DROP VERY LITTLE SUNDAY NIGHT.
.LONG TERM...MONDAY THROUGH THURSDAY NIGHT
325 AM CST FRI JAN 25 2013
25.00Z ECMWF/GFS/GFS ENSEMBLES ALL DEPICT A FAIRLY SIMILAR SCENARIO
THROUGH THE LONG TERM PERIOD...WHILE THE 25.00Z CANADIAN IS AN
OUTLIER. THE PERIOD STARTS OFF WITH TROUGHING OVER THE WESTERN U.S.
WITH BROAD RIDGING DOWNSTREAM OVER THE EASTERN U.S.. MEANWHILE...A
POTENT SHORTWAVE/UPPER LOW OF ARCTIC ORIGIN IS PRESENT OVER THE
NORTHWEST TERRITORIES. THE CANADIAN IS THE ONLY MODEL THAT EJECTS
OUT THE SOUTHERN PORTION OF THE WESTERN UPPER TROUGH AND PHASES IT
WITH SOME NORTHERN STREAM ENERGY...RESULTING IN A POSSIBLE SNOWSTORM
FOR THE AREA ON TUESDAY. THE REST OF THE MODELS SAY THERE IS NO
PHASING...AND IN THE CASE OF THE ECMWF...THE SOUTHERN PORTION
CUTS-OFF. WITH NO PHASING...MUCH OF MONDAY THROUGH TUESDAY ENDS UP
DRY. HAVE MAINTAINED SOME LOW PRECIPITATION CHANCES DURING THIS TIME
PERIOD...SINCE THE 25.00Z ECMWF AND GFS DO DEPICT A LITTLE LIGHT QPF
FROM WEAK SHORTWAVES COMING THROUGH IN THE SOUTHWEST FLOW.
AFTER TUESDAY...THE POTENT SHORTWAVE/UPPER LOW OF ARCTIC ORIGIN IS
PROGGED TO DIVE DOWN INTO THE UPPER MIDWEST BY 12Z WEDNESDAY. THE
AREA THEN GENERALLY REMAINS UNDER TROUGHING THROUGH THURSDAY NIGHT.
AS SUCH...850MB AND 925MB TEMPS TAKE A NOSE-DIVE. LATEST 25.00Z
ECMWF KEEPS 850MB TEMPS BELOW -20C AFTER 18Z WEDNESDAY...A DECENT
DROP FROM BEING UP BETWEEN 0 AND +4C AT 00Z TUESDAY. THUS BELOW
NORMAL TEMPERATURES LOOK LIKELY. ANY PRECIPITATION SHOULD BE
CONFINED TO BEFORE THE COLD AIR COMES IN...WITH ARCTIC HIGH PRESSURE
DOMINATING AFTERWARDS.
&&
.AVIATION...TODAY AND TONIGHT
535 AM CST FRI JAN 25 2013
LIGHT SNOW AND VSBY RESTRICTIONS HAVE MOVED OUT OF THE TAF SITES AS
OF 11Z. BKN-OVC CLOUD DECKS IN THE 3500 TO 5K FT RANGE WILL GIVE WAY
TO CLOUD DECKS IN THE 2K-3K FT RANGE LATER THIS MORNING AS SOME
MOISTURE WRAPPING AROUND A NORTHERN MN LOW AND ASSOCIATED WITH THE
TRAILING COLD FRONT SPREADS ACROSS THE AREA. MAY SEE A FEW FLURRIES
FROM THESE CLOUDS TODAY...BUT LEFT THIS OUT OF THE TAFS FOR NOW WITH
UPSTREAM OBS OVER CENTRAL/WEST-CENTRAL MN ALL 10SM AT THIS TIME.
THE COLD FRONT WILL PASS THRU THE TAF SITES LATER THIS MORNING WITH
WINDS BECOMING NORTHWEST AND INCREASING INTO THE 14-20KT G23-30KTS
FOR THE AFTERNOON. WITH RATHER FAST MOVING SYSTEMS...THE CLOUDS
ALREADY LOOK TO SCATTER OUT/DECREASE LATE THIS AFTERNOON/EARLY THIS
EVENING...WITH SKIES BECOMING CLEAR FOR THE LATE EVENING AND
OVERNIGHT HOURS. WINDS WILL DIMINISH RATHER QUICKLY THIS EVENING AS
WELL WITH THE CENTER OF THE NEXT CANADIAN HIGH EXPECTED TO BE
CENTERED NEAR THE MS RIVER BY 12Z SAT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
519 AM CST FRI JAN 25 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM....AJ
AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
519 AM CST FRI JAN 25 2013
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
325 AM CST FRI JAN 25 2013
MAIN FORECAST CONCERNS ARE ON SNOW AND WIND POTENTIAL TODAY...THEN
IF PRECIPITATION CAN OCCUR AND WHAT TYPE FOR SUNDAY INTO SUNDAY
NIGHT.
CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A POTENT TROUGH OFF THE PACIFIC NORTHWEST COAST...RIDGING
OVER THE NORTHERN U.S. ROCKIES INTO ALBERTA...A SHORTWAVE TROUGH
DIGGING INTO NORTHWEST MINNESOTA...AND A SHORTWAVE OVER SOUTHEAST
MINNESOTA. AHEAD OF THIS LATTER SHORTWAVE...WATER VAPOR...IR IMAGERY
AND SURFACE OBSERVATIONS SHOWED A LARGE EXPANSE OF MID AND HIGH
CLOUDS. RAP TROPOPAUSE ANALYSIS ALSO HAD A BROAD 120-140KT JET FROM
NEBRASKA TO OHIO DOWNSTREAM OF THE SHORTWAVE...ACTUALLY PLACING THE
FORECAST AREA IN THE SUBSIDENT LEFT ENTRANCE REGION. 00Z SOUNDINGS
FROM MPX...GRB AND DVN SHOWED A GREAT DEAL OF DRY AIR BELOW
700MB...WITH DEWPOINT DEPRESSIONS AS MUCH AS 30C. THIS DRY AIR HAS
BEEN EFFECTIVE AT MINIMIZING SNOWFALL OUT OF THE MID/HIGH CLOUDS
FROM REACHING THE SURFACE. THERE WAS HIGHER LOWER LEVEL MOISTURE OFF
TO THE WEST AT ABR AND OAX...NOTED BY ITS 00Z SOUNDING HAVING 850MB
DEWPOINT DEPRESSION BETWEEN 1-5C. THIS HAS BEEN SLOWLY ADVECTING
TOWARDS THE AREA REFLECTED BY SOUTHWEST 25-40KT WINDS ON PROFILER
AND VWP DATA. BETWEEN 06-08Z...SOME SNOW FINALLY GOT GOING...BUT THE
BACK EDGE BEHIND THE LEAD SHORTWAVE WAS RAPIDLY PUSHING EAST...WITH
KRST AND KCCY NOW DRY. TO THE NORTH...A BAND OF WARM ADVECTION SNOW
HAS BEEN ONGOING FROM NORTHERN MN INTO NORTHERN WI...DOWNSTREAM OF
THE NORTHWEST MN SHORTWAVE TROUGH. IN THE WAKE OF THIS SHORTWAVE
TROUGH...ANOTHER SURGE OF ARCTIC AIR WAS NOTED WITH TEMPERATURES IN
THE TEENS AND 20S BELOW ZERO OVER CENTRAL SASKATCHEWAN. THE COLD AIR
WAS IN THE WAKE OF A 1012MB SURFACE LOW IN NORTHWEST MN.
TODAY AND TONIGHT...MODELS ARE IN GOOD AGREEMENT DROPPING THE
SHORTWAVE TROUGH OVER NORTHWEST MINNESOTA ACROSS CENTRAL WISCONSIN
BY 18Z...THEN INTO SOUTHEAST LOWER MI BY 00Z. 500MB HEIGHTS SLOWLY
RISE THEREAFTER AS THE NORTHERN ROCKIES RIDGE SLIDES EASTWARD...
PLACING THE FORECAST AREA IN AN INFLECTION POINT BETWEEN A TROUGH
AND RIDGE AXIS BY 12Z SATURDAY. THE TROPOPAUSE DROPS NICELY THIS
MORNING WITH THE SHORTWAVE TROUGH MOVING IN...AS MUCH AS 100MB TO
NEAR 350MB ACROSS MUCH OF WISCONSIN BY 15Z. ALTHOUGH THIS IS GOOD
DYNAMIC FORCING...THE SCOURING OUT OF MID AND UPPER LEVEL MOISTURE
BY THE LEAD SHORTWAVE AHEAD OF THE TROUGH IS VERY PROBLEMATIC. AS
SUCH...MODELS HAVE BACKED OFF ON THE AMOUNT OF PRECIPITATION WITH
THE WARM ADVECTION AND DPVA AHEAD OF THE SYSTEM. THIS MATCHES TOO
WITH RADAR TRENDS...AND THUS HAVE SHORTENED THE END TIME OF THE
ADVISORY TO 12Z. IN FACT...WE MAY HAVE TO WAIT UNTIL THE
AFTERNOON...WHEN SNOW ACTUALLY LOOKS BETTER IN THE WAKE OF THE
SHORTWAVE TROUGH AND SURFACE LOW. THIS IS DUE TO COLD ADVECTION
COMBINING WITH LINGERING SURFACE MOISTURE TO PRODUCE CONVECTIVE
SNOW. THE 25.00Z NAM AND HIRES NMM RUNS ARE THE MOST BULLISH WITH
THE CONVECTIVE IDEA...WHILE ARW MODELS ARE NOT. IT APPEARS THE NMM
CORE MAY BE MOISTENING SURFACE DEWPOINTS UP TOO MUCH. TOOK A
COMPROMISE APPROACH WHICH RESULTS IN FLURRIES ALONG THE MS RIVER AND
SCATTERED SNOW SHOWERS NORTH OF I-94 WHERE THE BEST LOW LEVEL
INSTABILITY IS PRESENT. IN ADDITION TO THE SNOW...SETUP FOR THE
AFTERNOON IS FAVORABLE FOR WINDY CONDITIONS. THE COMBINATION OF COLD
ADVECTION...A TIGHT PRESSURE GRADIENT IN THE WAKE OF THE LOW...BEING
AT PEAK HEATING AND MIXING DEPTHS UP TO 875-900MB SHOULD YIELD GUSTS
IN THE 25-30 KT RANGE. EXPECT THE SNOW TO QUICKLY DIMINISH THIS
EVENING WITH LOSS OF HEATING AND THE SHORTWAVE TROUGH SHIFTING OFF.
WINDS LOOK TO TAKE SOME TIME DIMINISHING SINCE THE HIGH PRESSURE
AREA DOES NOT BUILD IN UNTIL LATE IN THE NIGHT...I.E. AT THE TIME OF
THE INFLECTION POINT IN THE FLOW AT 500MB. THE COMBINATION OF WIND
AND MUCH OF THE AREA STILL WITH NEAR BARE GROUND WILL KEEP LOWS
WARMER...ESPECIALLY COMPARED TO THE NAM WHICH HAS 5 INCHES ON THE
GROUND ACROSS THE FORECAST AREA. LEANED CLOSER TO THE ECMWF AND MAV
GUIDANCE FOR LOWS.
SATURDAY AND SATURDAY NIGHT...THE UPPER RIDGING OVER THE NORTHERN
ROCKIES IS PROGGED TO CONTINUE MARCHING EAST TOWARDS THE FORECAST
AREA DURING THIS TIME PERIOD...PUSHED ALONG BY TROUGHING OFF THE
PACIFIC NORTHWEST MOVING INLAND AS WELL AS AN UPPER LOW OFF THE
SOUTHERN CALIFORNIA COAST LIFTING INTO SOUTHEAST COLORADO. THE SHIFT
EAST OF THE UPPER RIDGE AXIS...REACHING EASTERN MN BY 12Z
SUNDAY...WILL SETUP A LOW LEVEL RETURN FLOW OVER THE FORECAST AREA
FOR THE AFTERNOON AND NIGHT. AN INCREASE OF MID/HIGH CLOUDS IS
LIKELY GIVEN THE WARM ADVECTION PATTERN...NOTED TOO BY 925MB TEMPS
CLIMBING FROM AROUND -12C AT 12Z SATURDAY TO -2 TO -6C BY 12Z
SUNDAY. THE QUESTION MARK IS LATE SATURDAY NIGHT...IF THE LOW LEVEL
MOISTURE WILL BE DEEP ENOUGH TO RESULT IN PRECIPITATION. THE 25.00Z
NAM/CANADIAN SUGGESTS THIS WOULD OCCUR FROM THE KANSAS CITY AREA
INTO NORTHEAST IOWA. COMPARED TO THE 25.00Z GFS/ECMWF/UKMET... THIS
SEEMS A LITTLE TOO FAR NORTH / FAST. THE OTHER MODEL GROUP KEEPS THE
BULK OF THE WARM ADVECTION PRECIPITATION SOUTH OF I-80. THUS...HAVE
KEPT THE ENTIRE PERIOD FROM 12Z SATURDAY TO 12Z SUNDAY DRY. WITH THE
WARMING 925MB TEMPS AND SOME SUN...HIGHS SHOULD BOUNCE BACK INTO THE
TEENS FOR SATURDAY. WARM ADVECTION PERSISTING THROUGH THE NIGHT PLUS
CLOUDS AROUND WILL LEAD TO RISING TEMPERATURES SATURDAY NIGHT.
SUNDAY AND SUNDAY NIGHT...THIS PERIOD REMAINS VERY PROBLEMATIC AND
UNCERTAIN. THE MAIN PROBLEM IS THE STRENGTH AND SPEED OF THE UPPER
LOW OFF THE SOUTHERN CALIFORNIA COAST LIFTING UP TOWARDS THE AREA ON
SUNDAY. THE SPREAD RANGES FROM:
1. A RELATIVELY STRONG 25.00Z GFS/CANADIAN...STILL SHOWING AT LEAST
A POTENT SHORTWAVE COMING THROUGH THE FORECAST AREA AROUND 06Z
MONDAY.
2. A REALLY WEAK 24.12Z/25.00Z ECMWF WHICH SHEAR THE UPPER LOW APART
AND HAVE ITS REMNANTS TRACK ALONG I-80.
THE 25.00Z NAM/UKMET LIE IN-BETWEEN THESE SCENARIOS. THE DIFFERENCES
NOT ONLY IMPACT WHETHER IT WILL PRECIPITATE...BUT ALSO WHAT TYPE
WOULD OCCUR IF IT DOES PRECIPITATE. THE ECMWF...BEING THE
WEAKEST...LIMITS THE AMOUNT OF MOISTURE RETURN INTO THE FORECAST
AREA FROM THE GULF OF MEXICO...AND NET RESULT IS A DRY FORECAST. THE
GFS/CANADIAN HAVE A MUCH STRONGER LOW LEVEL JET BECAUSE OF A STRONG
SHORTWAVE...THUS SPREAD PRECIPITATION OVER THE ENTIRE AREA. THIS
LATTER SCENARIO WOULD ALSO YIELD A SNOW TO SLEET TO FREEZING RAIN
SITUATION. ONCE THE SHORTWAVE GOES BY...THE PRECIPITATION DIMINISH.
SINCE ALL SCENARIOS SEEM PLAUSIBLE GIVEN THE MODELS HAVE MAINTAINED
GOOD CONTINUITY...HAVE COMPROMISED. THIS RESULTS IN A SLIGHT
LOWERING OF PRECIPITATION CHANCES FOR SUNDAY WHILE SUNDAY NIGHT WAS
PRETTY SIMILAR. FOR PRECIPITATION TYPE...BOTH SNOW AND FREEZING RAIN
SEEM EQUALLY LIKELY TO OCCUR...SINCE THERE ARE ALSO ISSUES WITH ICE
IN THE CLOUDS. HOPEFULLY MODELS WILL COME TOGETHER SOON. THE
TEMPERATURE FORECAST IS ALSO A COMPROMISE...BUT DECENT AGREEMENT
EXISTS THAT READINGS SHOULD GET UP CLOSE TO FREEZING ON
SUNDAY...THEN DROP VERY LITTLE SUNDAY NIGHT.
.LONG TERM...MONDAY THROUGH THURSDAY NIGHT
325 AM CST FRI JAN 25 2013
25.00Z ECMWF/GFS/GFS ENSEMBLES ALL DEPICT A FAIRLY SIMILAR SCENARIO
THROUGH THE LONG TERM PERIOD...WHILE THE 25.00Z CANADIAN IS AN
OUTLIER. THE PERIOD STARTS OFF WITH TROUGHING OVER THE WESTERN U.S.
WITH BROAD RIDGING DOWNSTREAM OVER THE EASTERN U.S.. MEANWHILE...A
POTENT SHORTWAVE/UPPER LOW OF ARCTIC ORIGIN IS PRESENT OVER THE
NORTHWEST TERRITORIES. THE CANADIAN IS THE ONLY MODEL THAT EJECTS
OUT THE SOUTHERN PORTION OF THE WESTERN UPPER TROUGH AND PHASES IT
WITH SOME NORTHERN STREAM ENERGY...RESULTING IN A POSSIBLE SNOWSTORM
FOR THE AREA ON TUESDAY. THE REST OF THE MODELS SAY THERE IS NO
PHASING...AND IN THE CASE OF THE ECMWF...THE SOUTHERN PORTION
CUTS-OFF. WITH NO PHASING...MUCH OF MONDAY THROUGH TUESDAY ENDS UP
DRY. HAVE MAINTAINED SOME LOW PRECIPITATION CHANCES DURING THIS TIME
PERIOD...SINCE THE 25.00Z ECMWF AND GFS DO DEPICT A LITTLE LIGHT QPF
FROM WEAK SHORTWAVES COMING THROUGH IN THE SOUTHWEST FLOW.
AFTER TUESDAY...THE POTENT SHORTWAVE/UPPER LOW OF ARCTIC ORIGIN IS
PROGGED TO DIVE DOWN INTO THE UPPER MIDWEST BY 12Z WEDNESDAY. THE
AREA THEN GENERALLY REMAINS UNDER TROUGHING THROUGH THURSDAY NIGHT.
AS SUCH...850MB AND 925MB TEMPS TAKE A NOSE-DIVE. LATEST 25.00Z
ECMWF KEEPS 850MB TEMPS BELOW -20C AFTER 18Z WEDNESDAY...A DECENT
DROP FROM BEING UP BETWEEN 0 AND +4C AT 00Z TUESDAY. THUS BELOW
NORMAL TEMPERATURES LOOK LIKELY. ANY PRECIPITATION SHOULD BE
CONFINED TO BEFORE THE COLD AIR COMES IN...WITH ARCTIC HIGH PRESSURE
DOMINATING AFTERWARDS.
&&
.AVIATION...
1111 AM CST THU JAN 24 2013
TIMING/CIGS/VSBYS REMAIN PROBLEMATIC WITH ASSOCIATED CLOUDS/EXPECTED
SNOW WITH SHORTWAVE TROUGH MOVING ACROSS THE REGION. CIGS HAVE
STARTED TO LOWER ACROSS THE REGION OVER THE LAST COUPLE HOURS...WITH
MORE RETURNS SHOWING UP ON RADAR...BUT NOT MUCH IN THE WAY OF -SN
REACHING THE SFC. RAP13/NAM12 CONTINUE TO SUGGEST RAPID SATURATION
OF THE DRY LOW LEVELS OVER THE NEXT FEW HOURS...WITH CIGS FOLLOWING
SUIT AND SOME -SN. NAM12 BUFKIT SOUNDINGS CAPTURED THE NEAR SFC DRY
LAYER THE BEST...COMPARED TO THE DVN 00Z SOUNDING...SO USING ITS
BUFKIT SOUNDINGS TO AID IN TIMING OF LOWER CIGS/-SN. STILL THINK A
DECENT CHANCE FOR SOME MVFR CIGS EARLY THIS MORNING...ALTHOUGH NOT
SOLD ON SUB 3SM -SN ANYMORE. SNOW ACCUMS LOOK MINOR...LESS THAN 1/2
AT KRST AND LESS THAN 1 INCH AT KLSE. IT WILL BE FLUFFY LOW WATER
CONTENT SNOW...SO IT WILL MOVE AROUND EASILY. DON/T EXPECT AN IMPACT
ON VSBYS UNLESS A FEW INCHES WOULD FALL.
BY LATE MORNING...A SFC COLD FRONT WILL BE SWEEPING THROUGH...WITH
COLD AIR ADVECTION AND SHARP LOW LEVEL LAPSE RATES BEHIND IT. THIS
COULD BRING A BETTER CHANCE FOR 2500 FT CIGS ALONG WITH SCT -SHSN.
ANY -SHSN COULD REDUCE VSBYS TO 2-3SM FOR A SHORT PERIOD...BUT NOT
ABLE TO TIME SO WILL LEAVE P6SM FOR NOW. IN ADDITION...EXPECT
BLUSTERY WINDS AS THEY TURN NORTHWEST BEHIND THE FRONT. THESE SHOULD
DIMINISH WITH NIGHT FALL AS HIGH PRESSURE STARTS TO BUILD IN FROM
THE PLAINS. LOOK FOR CLEARING SKIES ALSO...ALONG WITH AN END TO ANY
LINGERING -SHSN.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
519 AM CST FRI JAN 25 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
340 PM MST FRI JAN 25 2013
.SHORT TERM...MOUNTAIN WEB CAMS SHOWING ISOLATED LIGHT SNOW SHOWERS
ACROSS THE HIGHER PEAKS ACROSS SUMMIT AND GRAND COUNTIES. PERHAPS
SOME LIGHT SNOW SHOWERS ALSO OCCURRING OVER THE GORE AND PARK
MOUNTAINS OF WESTERN JACKSON COUNTY. OTHERWISE...MAINLY MOSTLY
CLOUDY SKIES OVER THE REGION WITH WESTERLY FLOW ALOFT. MODELS SHOW
THE WESTERLY FLOW ALOFT PERSISTING THROUGH THE EVENING...GRADUALLY
BECOMING SOUTHWEST OVERNIGHT AS AN UPPER TROUGH MOVES INTO THE
GREAT BASIN. LATEST RAP CROSS SECTIONS SHOW A GRADUAL LOWERING OF
THE MOISTURE ACROSS THE MOUNTAINS DURING THE EVENING...WITH THE
DEEPER MOISTURE AFTER MIDNIGHT. BOTH NAM AND GFS CROSS SECTIONS
INDICATE LESS MOISTURE. BASED ON LATEST SATELLITE LOOPS...NOT ALOT
OF DEEPER MOISTURE UPSTREAM OVER UTAH AND ARIZONA...SO THE RAP
MOISTURE COULD BE A BIT OVERDONE. AT ANY RATE...SHOULD GRADUALLY
SEE SOME LOWERING OF CLOUDS THROUGH THE EVENING ACROSS THE
MOUNTAINS. MODELS SHOW LAPSE RATES OF AROUND 6 C/KM ALONG...SO
SNOW CHANCES SHOULD BEGIN TO INCREASE WITH THE BEST ACROSS ZONE
31 AND PORTIONS OF 34 AFTER MIDNIGHT. AMOUNTS SHOULD REMAIN
LIGHT...AROUND AN INCH OR LESS. DRY CONDITIONS TO CONTINUE ACROSS
PLAINS. OVERNIGHT TEMPERATURES TO BE FAIRLY MILD GIVEN CLOUD COVER
AND LACK OF COLD AIR ADVECTION. ON SATURDAY...FLOW TO BECOME
SOUTHWEST WHICH SHOULD ALLOW FOR MORE MOISTURE TO STREAM OVER THE
AREA. MODELS SHOW AN INCREASE IN MID LEVEL QG ASCENT AHEAD OF AN
APPROACHING SHORTWAVE. THIS ASCENT COMBINED WITH MODEST LAPSE
RATES SHOULD HELP TO IMPROVE SNOW CHANCES ACROSS THE MOUTAINS.
SOUTHWEST FLOW TO CONTINUE TO FAVOR ZONE 31 AND WILL HAVE THE
HIGHER POPS THERE. DESPITE THE MODEST LAPSE RATES AND INCREASING
ASCENT...SNOW AMOUNTS SHOULD REMAIN FAIRLY LIGHT WITH UP TO TWO
INCHES ALONG SOUTHWEST FACING SLOPES. THERE MAY BE SOME ALONG THE
FOOTHILLS DURING THE AFTERNOON AS THE LIFT MOVES OVER THE AREA.
AND WILL KEEP THE SLIGHT CHANCE GOING. TEMPERATURES THERE LOOK
WARM ENOUGH FOR THE PRECIP TO BE RAIN. AS FOR PLAINS. LOW LEVELS
TOO DRY FOR ANY MENTION OF PRECIP...MAYBE SOME VIRGA IN AND NEAR
THE FOOTHILLS. CLOUD COVER TO KEEP TEMPERATURES FAIRLY COOL ACROSS
THE PLAINS...WITH HIGHS IN THE 50S.
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY...UNSETTLED WEATHER
PATTERN THOUGH THE PERIOD WITH SNOW POSSIBLE ACROSS THE HIGH
COUNTRY THIS WEEKEND THROUGH EARLY NEXT WEEK. MODEL CONFIDENCE IS
LOW AT THIS TIME WITH FORECAST UNCERTAINTIES ESPECIALLY EAST OF
THE MOUNTAINS DAYS 5 AND 6.
SATURDAY NIGHT THROUGH SUNDAY MORNING...WEAK SHORT WAVE EJECTS OUT
OF THE DESERT SOUTHWEST INTO COLORADO LATE SATURDAY. A MOIST
SOUTHWESTERLY FLOW ALOFT OVER COLORADO WILL BRING INCREASING CHANCES
OF SNOW TO THE HIGH COUNTRY AS WELL AS A FEW LIGHT SHOWERS TO THE
PLAINS SATURDAY NIGHT INTO SUNDAY MORNING. THE SNOW SHOULD BE LIGHT
DUE TO POOR OROGRAPHICS AND WARM ADVECTION AT MID LEVELS. THE RHEA-
THALER OROGRAPHIC SNOW MODEL SHOWS UP TO 2 INCHES OF SNOW IN THE
MOUNTAINS DURING THIS PERIOD.
SUNDAY AFTERNOON THROUGH MONDAY AFTERNOON...MOIST SOUTHWESTERLY FLOW
ALOFT CONTINUES OVER COLORADO AS AN UPPER LEVEL STORM SYTEM DEVELOPS
OVER THE WESTERN UNITED STATES. THIS PATTERN WILL BRING CONTINUED
LIGHT SNOW TO THE HIGH COUNTRY THROUGH THE PERIOD...WITH DRY WEATHER
EXPECTED EAST OF THE MOUNTAINS.
MONDAY EVENING THROUGH FRIDAY...MODEL DISCRENCIES CONTINUE WITH THE
GFS AND ECMWF HAVING VERY DIFFERENT SOLUTIONS DURING THIS PERIOD.
THE OPERATIONAL GFS RUN CONTINUES TO SHOW A LARGE OPEN WAVE TROUGH
MOVING ACROSS THE ROCKY MOUNTAIN REGION EARLY NEXT WEEK. THE ECMWF
SHOWS THE ENERGY FROM THE STORM SYSTEM SPLITTING...WITH PART OF THE
ENERGY DIGGING INTO THE DESERT SOUTHWEST WITH THE OTHER PART GETTING
CAUGHT UP IN THE NORTHERN BRANCH OF THE JET STREAM OVER THE NORTHERN
PLAINS STATES. IN ADDITION...OVER HALF OF THE GFS AND CANADIAN
ENSEMBLES HAVE A SIMILAR PATTERN TO THE ECMWF. BOTH SOLUTIONS WOULD
BRING COLDER TEMPERATURES TO NORTH CENTRAL AND NORTHEASTERN COLORADO
EARLY NEXT WEEK. HOWEVER...THE SNOWFALL POTENTIAL WITH THE SOLUTIONS
WOULD BE VASTLY DIFFERENT. THE GFS AND THE ECMWF HAVE A COLD FRONT
MOVING INTO NORTHEASTERN COLORADO MONDAY NIGHT...WITH UPSLOPE FLOW
DEVELOPING. THE GFS DEVELOPS A DEEPER UPLOPE FLOW WITH A MORE
PROLONGED PERIOD OF SNOWFALL ALONG THE FRONT RANGE AND EASTERN
PLAINS...WHILE THE ECMWF IS MORE SHALLOW AND ONLY PRODUCES A QUICK
SHOT OF LIGHTER SNOWFALL. FOR NOW I AM INCLINED TO FAVOR THE ECMWF.
THEREFORE...I HAVE MADE LITTLE CHANGES FOR THIS PERIOD AND HAVE ONLY
RAISED POPS TO THE CHANCE CATEGORY OVER THE PLAINS MONDAY NIGHT
INTO TUESDAY MORNING. MODELS SHOW A MOIST NORTHWEST FLOW ALOFT
DEVELOPING OVER COLORADO BY NEXT WEDNESDAY AS THE UPPER LEVEL
STORM SYSTEM MOVES EAST OF COLORADO. AS A RESULT...THE CHANCE OF
SNOW MAY CONTINUE ACROSS THE HIGH COUNTRY THROUGH THE END OF THE
WORK WEEK.
&&
.AVIATION...NORTHEAST WINDS PREVAILING ACROSS DEN AND APA...MORE
NORTHERLY AT BJC. WINDS TO WEAKEN DURING THE EVENING...BECOMING
SOUTHWEST AROUND 03Z AS DRAINAGE PATTERN DEVELOPS. GRADUAL
INCREASE IN MID AND HIGH LEVEL CLOUDS...WITH CEILINGS REMAING
ABOVE 10000 FEET. ON SATURDAY...WINDS TO REMAIN SOUTHERLY THROUGH
18Z...PERHAPS MORE SOUTHEAST AT DEN AND APA. SLIGHT CHANCE OF
CEILINGS OF AROUND 7000 FEET AGL DEVELOPING DURING THE AFTERNOON
WIT PERHAPS SOME VIRGA. FOR NOW WILL LEAVE OUT OF THE TAFS. VFR TO
CONTINUE.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....KALINA
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1007 AM MST FRI JAN 25 2013
.UPDATE...
&&
.SHORT TERM...MOUNTAIN WEB CAMS INDICATING MOST OF THE SNOW HAS
COME TO AN END...THOUGH SOME AREAS OF SNOW STILL LINGERING ACROSS
THE HIGHER RIDGES. LATEST RAP SHOWED THIS TREND OF ENDING THE SNOW
BY 18Z AS THE MOISTURE DEPTH DECREASES. STILL APPEARS SOME POCKETS
OF LOW LEVEL MOISTURE WILL PERSIST THROUGH THE AFTERNOON...MAINLY
ALONG WEST FACING SLOPES. LATEST UPDATE INCLUDED LOW POPS ACROSS
THE MOUNTAINS THROUGH THE AFTERNOON...WHICH SEEMS REASONABLE. FOR
THIS EVENING INTO TONIGHT...RAP INCREASES THE MOISTURE ONCE AGAIN
AS THE FLOW ALOFT BECOMES SOUTHWEST. THERE IS SOME INCREASE IN MID
LEVEL QG ASCENT WITH LAPSE RATES AROUND 5-6 C/KM. OTHER MODELS
LESS EXCITED WITH SNOW CHANCES. THOUGH THE OROGRAPHICS NOT
FAVORABLE FOR SNOWFALL...WILL UP THE MOUNTAIN POPS A BIT THIS
EVENING AND TONIGHT BASED ON THE ASCENT AND LAPSE RATES. WILL
WAIT FOR LATER DATA FOR ANY FURTHER POP INCREASE. WHATEVER SNOW
THAT FALLS SHOULD BE LIGHT. REST OF FORECASTS SEEM ON TRACK AT
THIS POINT. TEMPERATURES TO BE RATHER "BALMY` IN THE KREMMLING
AREA TODAY...
.AVIATION...LATEST RAP AND HRRR INDICATING SOME SORT OF
MESOCYCLONE DEVELOPING IN THE DENVER AREA DURING THE AFTERNOON
WHICH COULD TURN THE WINDS AND DEN AND APA TO THE NORTHEAST. WILL
TREND THE TAFS IN THAT DIRECTION AFTER 22Z. REST OF TAF TRENDS
LOOK ON TRACK.
&&
.PREV DISCUSSION... /ISSUED 412 AM MST FRI JAN 25 2013/
SHORT TERM...LAST NIGHTS WEAK WAVE IS MOVING OUT OF COLORADO WITH
SOME DRYING BEHIND IT. FLOW ALOFT BECOMING MORE WESTERLY AGAIN AND
DECREASING. THERE IS STILL A LITTLE WIND IN THE MOUNTAINS...BUT
NOT AS MUCH AS THE LAST COUPLE OF DAYS. HUMIDITIES ALSO HIGHER
TODAY AS ALL THAT DRY AIR HAS FINALLY BEEN DISPLACED. HIGH CLOUDS
WILL BE COMING AND GOING...EXPECT AN INCREASE AGAIN THIS AFTERNOON
AS THE MORE WESTERLY FLOW BRINGS THE EDGE BACK OVER US...THEN SOME
DECREASE AGAIN OVERNIGHT. MEANWHILE THE LOWER CLOUDS THAT HAVE
PUSHED OVER GRAND AND SUMMIT COUNTIES FROM THE GREAT BASIN SHOULD
BE PERSISTENT. THE BIGGEST CHANGE IS THAT THE COLD POOL IN GRAND
COUNTY IS FINALLY GONE...SO WHILE THE AIRMASS WILL STILL BE RATHER
STAGNANT HERE IT IS A MILDER AND MOIST ONE. THE BIGGEST CHANGE
THIS MORNING HAS BEEN TO DEAL WITH THE TEMPERATURES IN THAT
AREA...WENT WITH A MOS BLEND WHICH IS UP TO 30 DEGREES WARMER THAN
WHAT WE HAD AT KREMMLING. ELSEWHERE THE PREVIOUS FORECAST IS STILL
IN GOOD SHAPE.
LONG TERM...SATURDAY AND SATURDAY NIGHT...A MOIST SOUTHWESTERLY
FLOW ALOFT WILL BE OVER WESTERN COLORADO. A WEAK SHORT WAVE
TROUGH EMBEDDED IN THE FLOW ALOFT IS EXPECTED TO MOVE ACROSS THE
STATE SATURDAY NIGHT. QG ASCENT GENERATED BY THE MDLS IS WEAK BUT
THERE IS FAVORABLE MID LEVEL INSTBY WITH 700-500 LAPSE RATES
AROUND 7.5C/KM. SWLY FLOW AT 700 MB WILL FAVOR ZONE 31 THE MOST.
AS A RESULT...EXPECT ONLY LIGHT ACCUMULATIONS ALONG WEST AND
SOUTHWEST FACING SLOPES. ALTHOUGH MDLS GENERATE A LITTLE BIT OF
QPF SURVIVING AS THE TROUGH AXIS MOVE ACROSS THE EASTERN PLAINS OF
COLORADO LATE SATURDAY NIGHT...SUSPECT MORE VIRGA VS ISOLD SHOWER
ACTIVITY.
SUNDAY AND SUNDAY NIGHT...A SHORT WAVE RIDGE WILL ALLOW FOR A
DECREASING CHANCE OF SNOW IN THE MOUNTAINS WITH MID LEVEL WARM AIR
ADVECTION STABILIZING THE AIRMASS. FLOW ALOFT WILL REMAIN
SOUTHWESTERLY AHEAD OF THE NEXT SYSTEM DROPPING OUT OF THE PACIFIC
NORTHWEST.
MONDAY THROUGH TUESDAY...TIMING AND TRACK DISCREPANCIES CONTINUE
TO PERSIST IN THE MDLS REGARDING THE NEXT SYSTEM. WILL MAKE LITTLE
IF ANY ADJUSTMENT IN THIS PERIOD...CARRYING CHC POPS IN THE MTNS
WITH SLGT CHC POPS OVER THE NORTHEAST PLAINS. THE TROF AXIS IS
EXPECTED TO SHIFT TO THE EAST MONDAY EVENING...WITH COLD AIR
ADVECTION AND MORE FAVORABLE OROGRAPHIC DEVELOPING AS THE
RIDGETOP WINDS BECOME NORTHWESTERLY. COULD SEE SOME BANDED PCPN
DEVELOPING OVER THE CWFA ON MONDAY AS A 120+ KT UPPER JET AHEAD
OF THE NEXT SYSTEM TRAVERSES SOUTHEAST ACROSS THE STATE. THE
STRONGEST QG ASCENT IS PROGGED TO PASS TO THE WEST AND SOUTH OF
COLORADO...WITH MORE SUBSIDENCE EXPECTED OVER THE CWFA ON TUESDAY.
WEDNESDAY THROUGH THURSDAY...A DRY AND STABLE NORTHWESTERLY FLOW
ALOFT WILL BE OVER THE STATE...WITH A GRADUAL TEMPERATURE RECOVERY
BY MID-WEEK.
AVIATION...VFR CONDITIONS THROUGH TONIGHT. WINDS WILL GENERALLY
BE LIGHT SOUTHEAST TODAY AT KDEN/KAPA...LIKELY BECOMING NORTHEAST
OR VARIABLE FOR A FEW HOURS LATE IN THE AFTERNOON. KBJC MAY SEE A
PERIOD OF WEST WINDS THIS MORNING...BUT SHOULD SWITCH TO AN EAST
OR NORTHEAST DIRECTION THIS AFTERNOON.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....COOPER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
403 PM EST FRI JAN 25 2013
.SYNOPSIS...
FAST MOVING LOW PRESSURE WILL PIVOT ACROSS THE REGION THROUGH
THIS EVENING. HIGH PRESSURE BUILDS IN FROM THE WEST LATE
TONIGHT...AND PREVAILS OVER THE REGION OVER THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
REGIONAL RADAR MOSAIC SHOWS BAND OF LIGHT TO MOD SNOW HAS PUSHED
ACROSS AKQ CWA AS EXPECTED OVER THE PAST FEW HOURS, WITH AXIS
DENOTING BACK END OF SIGNIFICANT SNOWFALL NOW SLIDING ACROSS FAR
NORTHERN ZONES...AND SNOW ALREADY APPEARS TO BE DIMINISHING IN
INTENSITY ACROSS FAR NORTHERN TIER OF CWA. DRY SLOT EVIDENT ON
EARLY AFTERNOON WV SAT IMAGERY HAS ALREADY PUNCHED INTO THIS
AREA...AND WHILE PDS OF LIGHT SNOW SHUD CONTINUE FOR ANOTHER FEW
HRS, SNOWFALL TOTALS AOB 1" WILL BE COMMON OVER NORTHERN TIER OF
THE AREA (INCLUDING SALISBURY, TAPPAHANNOCK, CRISFIELD). DUE TO
EVENING RUSH HOUR UPCOMING, WL RETAIN WINTER WX ADVY OVER THESE
AREAS, BUT ANTICIPATE HEADLINE MAY BE ABLE TO BE REDUCED IN AREAL
COVERAGE SHORTLY THEREAFTER. FARTHER SOUTH, PDS OF STEADIER SNOW
WILL CONTINUE OVER SOUTH CENTRAL/SOUTHEASTERN VA FOR ANOTHER 3-4
HOURS...WITH TOTAL ACCUMS LIKELY SETTLING BETWEEN 1-3" AS BEST
FRONTOGENETIC FORCING DEVELOPS AND SWINGS ACROSS SOUTH CENTRAL VA
OVER TO THE LOWER EASTERN SHORE. P-TYPE WL BECOME AN ISSUE MAINLY
SOUTH OF US-58 W/INCREASING SSW FLOW. AN INTRUSION OF A WARM NOSE
(WARM AIR ALOFT W/AIR TEMP >0C) BETWEEN H85-65. AS WE`VE SEEN TO
THE WEST/SOUTHWEST ACROSS THE TN VLY THIS MORNING AND CENTRAL NC
ERY THIS AFTN, A RESULTANT MIX OR CHANGE TO FZRA (MIXED WITH IP AT
TIMES) IS EXPECTED OVER PARTS OF THE LOCAL AREA MAINLY ALONG AND S
OF THE VA/NC BORDER, EVENTUALLY NOSING INTO EXTREME SE VA JUST
BEFORE PCPN TAPERS OFF. WARM NOSE HAS ALREADY MADE MORE PROGRESS
NORTH THAN MODELS ANTICIPATED AND THUS HV BEEN A BIT MORE GENEROUS
THAN RUC DEPICTION OF THIS FEATURE THROUGH 05Z/MIDNIGHT. EXPECT
THAT PORTIONS OF NE NC AWAY FROM THE ATLANTIC COAST AND THE
ALBEMARLE SOUND SHOULD TRANSITION TO FREEZING RAIN AFTER 22Z,
TAPERING OFF BY MIDNIGHT TO A PERIOD OF LGT FZDZ AS COLUMN DRYING
CONTINUES THROUGH THE NIGHT FROM NW TO SE. ANY ICE ACCUMULATION
SHOULD BE ON THE ORDER OF A TENTH OF AN INCH OR LESS.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
DRY WNW FLOW PREVAILS BEHIND THE SYSTEM OVER THE WEEKEND AS THE
LOW RAPIDLY DEEPENS WELL OFFSHORE AND SURFACE HIGH PRESSURE
REBUILDS FROM THE WEST. FORECAST MAXIMA GENERALLY RANGING FROM
THE LOW/MID 30S N...TO AROUND 40 S (THESE VALUES AREA SLIGHTLY
BELOW GUIDANCE BASED ON FORECAST SNOW COVER OVER MUCH OF THE AREA).
SFC HIGH SLIDES OVERHEAD SUNDAY...SCOOTING OFFSHORE BY SUNDAY
NIGHT/MON MORNING. HV AGAIN UNDERCUT GUIDANCE FOR HIGHS ON SUNDAY,
WITH ANOTHER DRY DAY EXPECTED. HIGHS ONCE AGAIN M/U 30S TO NR 40.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
IN THE LONGER TERM...WHILE THE MODELS OVERALL SHOW A SIMILAR PATTERN
WITH A DEVELOPING RIDGE OVER THE SOUTHEASTERN US TO START THE PERIOD
ON SUNDAY NIGHT INTO MONDAY...THE MODELS STRUGGLE IN THE HANDLING OF
THAT RIDGE AND AS A RESULT THE MODEL TIMING AND STRENGTH OF THE
FRONT IS MUCH DIFFERENT IN THE 00Z AND 12Z MODELS. AT THIS
TIME...HAVE LEANED MORE TOWARD THE NAM TIMING...WHICH IS CLOSER TO
THE OVERALL PATTERN OF THE ECMWF. THE GFS IS SLOWER AND MORE
AMPLIFIED THAN THE ECMWF AND WHILE IT CAN NOT BE DISCOUNTED...IT
SEEMS LESS LIKELY.
FOR SUNDAY NIGHT INTO MONDAY...THE MODELS SHOW A DEVELOPING WARM
ADVECTION PATTERN AS THE SURFACE HIGH SETTLES OVER THE WESTERN
ATLANTIC. AS THE SW FLOW ALOFT DEVELOPS AND MOISTURE
INCREASES...COULD SEE SOME LIGHT PRECIP DEVELOP AFTER 6Z MONDAY
THROUGH 18Z...MAINLY ACROSS NRN AND WESTERN SECTIONS OF THE CWA.
THE BIG QUESTION IS THE SFC TEMPERATURES AS GUIDANCE SHOWS VALUES
FALLING INTO THE MID TO UPPER 20S AS THE LOW LEVEL SATURATES. THIS
COULD LEAD TO SOME LIGHT WINTRY PCPN. WILL NEED TO MONITOR THIS
GOING FORWARD. BY MID AFTERNOON...SHOULD SEE ENOUGH WARM AREA MOVE
INTO TO TURN ANY LINGER PCPN TO RAIN. THE RIDGE SHOULD AMPLIFY
ENOUGH BY MON NIGHT AND TUESDAY TO PUSH THE SFC FRONT WELL TO THE
NORTH AND TAKE THE ISENTROPIC LIFT TO THE NORTH AS WELL. THIS
SHOULD ALLOW A 36 TO 48 HR WINDOW OF MILD AND DRY WEATHER.
THE NEXT COLD FRONT STILL HAS LOTS OF QUESTIONS FROM STRENGTH TO
TIMING. AT THIS POINT...HAVE CONTINUED THE IDEA THAT THE FRONT WILL
CROSS THE REGION DURING THE DAY ON WEDNESDAY AND WITH A LESS
AMPLIFIED UPPER TROUGH...WILL SEE MORE OF AN ANAFRONT BOUNDARY WITH
OVERRUNNING RAIN. THE GFS GETS MUCH MORE AMPLIFIED AND SLOWS THE
FRONT DOWN SO THAT IT COME THROUGH ON THURSDAY AND IS MUCH
STRONGER. BUT FOR NOW...DO NOT SEE THE RATIONAL FOR THE STRONGER
TROUGH AS THE PATTERN SEEMS TO BE MORE PROGRESSIVE. SO HAVE FOCUSED
50 POPS FOR WEDNESDAY AND THEN ALLOWED FOR MUCH DRIER AND COOLER AIR
TO ARRIVE FOR THE END OF THE WEEK. THE 00Z ECMWF SHOWED A
DEVELOPING SRN STREAM LOW AND MADE A MID ATLANTIC SNOW STORM FROM
IT...BUT THE 12Z RUN BACKED OFF AND WITH THE MORE DOMINANT NRN
STREAM IN PLACE...HAVE KEPT FRIDAY DRY AT THIS POINT.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
WARM ADVECTION PATTERN IS SETTING UP AND PRECIPITATION HAS SPREAD
ACROSS WESTERN PORTIONS OF VIRGINIA AND NC AT THIS TIME. WATER
VAPOR IMAGERY SHOWS STRONG JET DIVING SOUTHEASTWARD TOWARD THE MID
ATLANTIC STATES WHICH SHOULD PROVIDE AN EXTRA ENHANCEMENT TO THE
LIFT AS THE PRECIPITATION MOVES INTO EASTERN VA/NC. LOOKING AT
UPSTREAM OBSERVATIONS...THE CEILINGS HAVE BEEN SLOW TO LOWER WITH
THE INITIAL SNOW SO HAVE BEEN SLOWER TO LOWER THE CEILINGS HOLDING
INITIALLY JUST ABOVE MVFR LEVELS BEFORE GRADUALLY LOWERING BELOW
1500 FT FOR RIC AND SBY SINCE THE LIFT AND CONSEQUENTLY THE SNOW
FALL INTENSITY LOOKS TO BE LIGHTER. FOR PHF/ORF...WHERE THE LIFT
IS STRONG AND THE PCPN INTENSITY LOOKS GREAT HAVE ALLOW FOR 500 TO
800 FT CEILINGS IN THE SNOW FOR SHORT 3 TO 4 HOUR WINDOW. ECG WILL
BE IN THE BETTER LIFT AND PCPN AS WELL...BUT THE SOUNDINGS SHOW
THAT ENOUGH WARM AIR AT AROUND 900 MB WILL PUSH NORTH CAUSING THE
SNOW TO MELT ALLOWING FOR SOME IP/ZR TO DEVELOP BETWEEN 00Z AND
4Z.
THE ENTIRE SYSTEM PUSHES OFF THE COAST BY 6Z WITH THE FLOW
TURNING NORTHWEST...WHICH WILL PUSH DRIER AIR BACK INTO THE
REGION. HIGH PRESSURE ARRIVES ON SATURDAY AND SLOWLY MOVES ACROSS
THE AREA AND OFF THE EAST COAST BY MONDAY...WHILE PROVIDING VFR
CONDITIONS.
&&
.MARINE...
HIGH PRESSURE WILL CONTINUE TO SLIDE OFFSHORE THROUGH THIS AFTN
AND WINDS WILL BECOME SW 10-15 KT ON AVERAGE. A LOW PRESSURE
SYSTEM WILL CROSS THE WATERS THIS EVENING AND STRENGTHEN AS IT
MOVES JUST OFF THE MID ATLANTIC COAST TONIGHT. AS THIS
OCCURS...WINDS WILL VEER TO THE NORTHWEST AND A SURGE OF SCA
CONDITIONS (15-20 KT BAY/RIVERS...20-25 KT SOUND/OCEAN) SHOULD BE
ANTICIPATED DURING THIS TIME. WAVES ON CHES BAY WILL INCREASE TO
3-4 FT AND SEAS WILL STAY AROUND 3-4 FT. BY SATURDAY
MORNING THE LOW IS WELL OFFSHORE AND A SFC PRESSURE GRADIENT
TIGHTENS ALONG THE COAST. THERE IS JUST ENOUGH INSTABILITY AND A
DECENT TEMPERATURE GRADIENT THAT DEVELOPS TO CONTINUE SCA FLAGS
THROUGH SAT INTO SAT NIGHT BEFORE WINDS AND SEAS SUBSIDE. WAVE ON
CHES BAY WILL AGAIN BE 3-4 FT ON AVERAGE AND SEAS WILL QUICKLY
BUILD TO 4-6 FT SAT MORNING. IN NORTHWEST FLOW...SEAS WILL BE SLOW
TO SUBSIDE AND SHOULD HOVER AROUND 5 FT NEAR 20 NM UNTIL EARLY SUN
MORNING.
HIGH PRESSURE BUILDS IN FROM THE NORTHWEST ON SUNDAY AND GRADUALLY
SLIDES SOUTHEAST OFF THE WRN ATLANTIC COAST EARLY NEXT WEEK. QUIET
CONDITIONS ARE ANTICIPATED DURING THIS TIME AS WINDS AVERAGE 10-15 KT...
WITH NW WINDS ON SUN...BECOMING S-SW MON THROUGH WED. THE NEXT LOW
PRESSURE SYSTEM APPROACHES THE REGION DURING THE MID TO LATE WEEK
TIMEFRAME.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY UNTIL 1 AM EST SATURDAY FOR MDZ021>025.
NC...WINTER WEATHER ADVISORY UNTIL 1 AM EST SATURDAY FOR NCZ012>017-
030>032-102.
VA...WINTER WEATHER ADVISORY UNTIL 1 AM EST SATURDAY FOR VAZ065-066-
077>082-084>100.
WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
VAZ060-063-064-067-068-070>076-083.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 AM EST
SUNDAY FOR ANZ652-654-656-658.
SMALL CRAFT ADVISORY FROM 10 AM SATURDAY TO 6 AM EST SUNDAY
FOR ANZ650.
SMALL CRAFT ADVISORY FROM 10 AM SATURDAY TO MIDNIGHT EST
SATURDAY NIGHT FOR ANZ636.
SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 6 AM EST SUNDAY
FOR ANZ630>634.
SMALL CRAFT ADVISORY FROM 10 AM TO 6 PM EST SATURDAY FOR
ANZ635.
SMALL CRAFT ADVISORY FROM 6 AM SATURDAY TO 6 AM EST SUNDAY FOR
ANZ638.
&&
$$
SYNOPSIS...MAM
NEAR TERM...AJZ/MAM
SHORT TERM...AJZ/MAM
LONG TERM...TMG
AVIATION...ESS
MARINE...BMD
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1250 PM EST FRI JAN 25 2013
.AVIATION...
//DISCUSSION...
THE INITIAL WAVE OF MOISTURE FOR LIGHT SNOW WILL RUN ITS COURSE IN
THE DETROIT AREA DURING THE EARLY AFTERNOON LEAVING AT LEAST
INTERVALS OF VFR CONDITIONS. LIGHT SNOW WILL LINGER FOR A GREATER
PART OF THE DAY FROM FNT NORTHWARD MOSTLY IN MVFR BUT WITH
INTERVALS OF IFR DUE TO VISIBILITY RESTRICTION. THE APPROACH OF
SURFACE LOW PRESSURE TONIGHT, AND THE ASSOCIATED CONVERGENT LOW
LEVEL FLOW, WILL MIX WITH LAKE MOISTURE TO BRING MVFR CEILING TO
ALL AREAS. RESIDUAL LIGHT SNOW IS EXPECTED TO AFFECT MAINLY THE
FNT TO MBS AREA DURING THE EVENING BEFORE PASSAGE OF THE LOW
BRINGS THE WIND AROUND TO THE NORTHWEST BY MID SATURDAY MORNING.
INITIAL INDICATIONS ARE THAT THE LOW LEVEL WIND PATTERN WILL BE
DRY AND NEUTRAL ENOUGH TO HELP BREAK UP MVFR CEILING FOR THE REST
OF THE DAY.
FOR DTW... WIDELY VARYING CONDITIONS DURING THE AFTERNOON AND
EVENING WILL BE FIRST MARKED BY SNOW DIMINISHING WITH LITTLE OR NO
ADDITIONAL ACCUMULATION. A PERIOD OF VFR CONDITIONS, BUT WITH
CEILING BELOW 5000 FEET, WILL BE LEFT BEHIND FOR THE MID TO LATE
AFTERNOON BEFORE MVFR CEILING RETURNS AS LOW PRESSURE CROSSES
CENTRAL LOWER MICHIGAN TONIGHT. ANY ADDITIONAL SNOW SHOWERS ARE
EXPECTED TO REMAIN NORTH OF DTW TONIGHT. DEVELOPMENT OF NORTHWEST
WIND OVERNIGHT THROUGH SATURDAY MORNING WILL HELP IMPROVE CEILING BY
SATURDAY AFTERNOON.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET THIS AFTERNOON AND
TONIGHT.
&&
.PREV DISCUSSION...ISSUED 1103 AM EST FRI JAN 25 2013
UPDATE...
EXPECT LIGHT SNOW TO DIMINISH DURING THE AFTERNOON, ESPECIALLY IN
THE DETROIT AREA WHERE SYSTEM RELATIVE ISENTROPIC LIFT WILL BE ON
THE WANE. AN INFUSION OF DRY AIR WILL BE THE EVIDENCE OF MID
LEVEL THETA-E DISRUPTION WITH THE MODEST DRY SLOT POSSIBLY
REACHING AS FAR NORTH AS FLINT BUT LIKELY NOT AS FAR NORTH AS THE
TRI CITIES BEFORE THE UPPER LEVEL WAVE APPROACHES FROM WISCONSIN
TOWARD EVENING. EXPECT THIS WAVE TO RENEW ISENTROPIC LIFT AHEAD OF
ITS TRACK AND BRING A COMPONENT OF DYNAMIC FORCING THAT WILL HELP
BOOST COVERAGE OF LIGHT SNOW BUT AGAIN AFFECTING MAINLY THE TRI
CITIES AND NORTHERN THUMB DURING THE EVENING. THIS UPDATE WILL
ADDRESS THE DIMINISHING TREND IN THE DETROIT AREA WITH AFTERNOON
OBSERVATIONS UPSTREAM HELPING ADDRESS EVENING EXPECTATIONS WITH
THE AFTERNOON PACKAGE.
PREV DISCUSSION...ISSUED 342 AM EST FRI JAN 25 2013
SHORT TERM...TODAY AND TONIGHT
AN APPROACHING CLIPPER SYSTEM WILL BRING ACCUMULATING SNOW TO
SOUTHEAST MICHIGAN TODAY AND TONIGHT. THE MAIN QUESTION REMAINS HOW
MUCH SNOW WILL FALL FROM THIS SYSTEM AS IT TRACKS THROUGH THE
CENTRAL GREAT LAKES. REGIONAL 00Z RAOB SOUNDINGS FROM KDTX/KAPX/KGRB
SHOW A VERY DRY AIRMASS BETWEEN 700 AND 500 MB WHICH NEEDS TO BE
OVERCOME BEFORE SNOWFALL CAN BEGIN IN EARNEST ACROSS SOUTHEAST
MICHIGAN. THE AMOUNT OF DRY AIR IS CONCERNING WITH RELATIVE HUMIDITY
VALUES FALLING TO AROUND 10 PERCENT IN THIS LAYER. HOWEVER AS KGRB
HAS PROVED THIS LAYER CAN BE OVERCOME AS NORTHEAST WISCONSIN IS
CURRENTLY GETTING ACCUMULATING SNOWFALL. WHILE THIS DRY AIR MAY NOT
PREVENT THE INEVITABLE...IT WILL PROBABLY DELAY THE ONSET OF THE
SNOWFALL WHICH THE NAM AND HRRR MODEL DEPICT RATHER WELL THIS RUN.
WHAT THIS SYSTEM LACKS IN MOISTURE IT MAKES UP FOR IN FORCING WITH
UPPER LEVEL DIVERGENCE IN THE LEFT EXIT REGION OF A STRONG 130 KNOT
JET DIVING SOUTH OVER THE SOUTHERN GREAT LAKES AND A STRONG MID
LEVEL SHORTWAVE CLEARLY EVIDENT ON WATER VAPOR IMAGERY CURRENTLY
SITUATED OVER THE UPPER MISSISSIPPI VALLEY. WHILE THESE DYNAMICS
WILL NOT MAKE UP FOR THE LACK OF MOISTURE...THEY WILL BE ABLE TO
TAKE ADVANTAGE OF THE MEAGER MOISTURE IN PLACE WITH AN ADDED BOOST
FROM LOW WATER CONTENT SNOW AS SNOW RATIOS OF 18 TO 19 TO 1 ARE
EXPECTED. WITH DRIER MODEL SOLUTIONS YIELDING QPF IN THE 0.05 TO
0.10 RANGE SNOWFALL AMOUNTS IN THE 1 TO 2 INCH RANGE SEEM REASONABLE
FROM THIS SYSTEM DURING THE TIME OF BEST FORCING BETWEEN 12Z AND 18Z.
THE HEADLINE QUESTION NEEDS TO BE ADDRESSED GIVEN THE BULK OF THE
SNOW IS EXPECTED IN A SHORT WINDOW OF A FEW HOURS WITH COLD SURFACE
TEMPERATURES IN THE SINGLE DIGITS UP TO THE MIDDLE TEENS EXPECTED TO
RENDER REGULAR ROAD SALT VERY INEFFICIENT FOR MELTING SNOW AND ICE
DURING THE MORNING HOURS. DESPITE THESE FACTORS THE DELAYED ONSET OF
THE SNOW WILL BE HELPFUL IN LIMITING THE EFFECT OF THESE CONDITIONS
ON THE MORNING COMMUTE. IN ADDITION UPSTREAM OBSERVATIONS ACROSS
WISCONSIN ARE NOT THAT IMPRESSIVE WITH VISIBILITIES GENERALLY AT OR
ABOVE 1 MILE. WITH THIS IN MIND PLAN TO HANDLE THE SNOW WITH SPECIAL
WEATHER STATEMENTS AS IT TRACKS EAST AND FORGO HEADLINES GIVEN MOST
OF THE IMPACT WILL BE AFTER THE MORNING COMMUTE.
ALTHOUGH THE MAIN FORCING FROM THE SYSTEM WILL BE EAST DURING THE
LATE AFTERNOON HOURS THE LOW ITSELF AND COLD FRONT WILL NOT MOVE
THROUGH UNTIL THE EVENING HOURS. THIS WILL MEAN LIGHT SNOW SHOWERS
WILL CONTINUE THROUGH THE OVERNIGHT HOURS...HOWEVER WITH THE BEST
FORCING AND MOISTURE OFF TO THE EAST ONLY A DUSTING OF ADDITIONAL
ACCUMULATION IS EXPECTED AFTER 18Z.
CLOUD COVER IS EXPECTED FOR MUCH OF THE DAYTIME HOURS...LIMITING
INCOMING SOLAR RADIATION. DESPITE SOUTHERLY SURFACE WINDS AHEAD OF
THE LOW...THE AIRMASS TO THE SOUTH IS NOT MUCH WARMER THAN THE ONE
CURRENTLY IN PLACE...OFFERING LITTLE TO NO WARM AIR ADVECTION TO
BOOST SURFACE TEMPERATURES. THEREFORE HIGHS ARE EXPECTED TO BE
IN THE LOW TO MID 20S THIS AFTERNOON. CONTINUED CLOUD COVER
OVERNIGHT AND NOT MUCH COLD AIR ADVECTION BEHIND THE COLD FRONT WILL
MEAN OVERNIGHT LOWS WILL GENERALLY BE IN THE 10 TO 15 DEGREE RANGE.
LONG TERM...SATURDAY THROUGH THURSDAY
BRIEF PERIOD OF DEEPER NORTHWEST FLOW TAKES HOLD ON SATURDAY IN THE
WAKE OF THE EXITING CLIPPER SYSTEM AND ALONG THE FRONT FACE OF THE
EXPANDING LOW TO MID LEVEL ANTICYCLONIC FLOW FILLING ACROSS THE UPPER
MS VALLEY. SHEAR AXIS EMBEDDED WITHIN THE WEAKENING CYCLONIC FLOW
WILL REMAIN DRAPED ACROSS THE REGION DURING THIS TIME. THIS BROAD
ASCENT WORKING INTO A DEEPENING CONVECTIVE LAYER AND A MOIST LAYER
THAT REMAINS FAVORABLY SATURATED WITH RESPECT TO ICE /-10 TO -14C
ISOTHERM/ WILL SUPPORT SOME VERY LIGHT SNOW SHOWER/FLURRY PRODUCTION
DURING THE DAY. IN ADDITION...BANDS OF LAKE DRIVEN SNOWFALL
ANCHORED ON THE LAKE HURON AGGREGATE TROUGH AXIS WILL TEND TO SHIFT
SOUTH-SOUTHEAST DOWN THE LONG FETCH IN RESPONSE TO INCREASING
PRESSURE AND A VEERING NORTHERLY WIND EMERGING ACROSS NORTHERN
PORTIONS OF THE LAKE. THE POTENTIAL DOES EXIST FOR THE WESTERN
PERIPHERY OF THIS BAND TO SWEEP ACROSS THE EASTERN THUMB SATURDAY
MORNING...BRINGING A QUICK SHOT OF ACCUMULATING SNOW. DRYING
NORTHERLY FLOW AND THE LOSS OF THE DIURNAL HEATING CYCLE WILL
SCATTER ANY LINGERING STRATOCU SATURDAY EVENING. HIGH CLOUDS WELL
IN ADVANCE OF THE NEXT SYSTEM MAY BE PROBLEMATIC FOR MAXIMIZING AN
OTHERWISE IDEAL SETUP FOR TEMPERATURES TO REALLY PLUMMET
/DIMINISHING GRADIENT...SNOW COVERAGE GROUND/. COLDEST LOCALES
CERTAINLY CAN MAKE A RUN TOWARD THE LOWER SINGLE DIGITS SUNDAY
MORNING GIVEN THE STRENGTH OF THE RESIDENT AIRMASS.
MID LEVEL CIRCULATION CURRENTLY ANCHORED OFF THE SOUTHERN CA
COASTLINE WILL RECEIVE THE NECESSARY NUDGE EASTWARD OVER THE WEEKEND
AS STRONG MID LEVEL ENERGY CRASHING INTO THE WEST COAST CARVES OUT
A DEEP LONG WAVE TROUGH. SHEARED WAVE EXPECTED TO EMBED WITHIN AN
INCREASING WEST-SOUTHWEST UPPER HEIGHT FIELD DOWNSTREAM...
TRANSLATING ACROSS SE MICHIGAN SUNDAY NIGHT. THIS PROCESS WILL
OCCUR COINCIDENT TO AND LIKELY ENHANCES A CORRIDOR OF WARM AIR
ADVECTION AND MOIST ISENTROPIC ASCENT THAT EMERGES IN INCREASING LOW
LEVEL SOUTHERLY FLOW. STRONG MODEL SUPPORT EXISTS IN DRIVING THIS
FORCING FIELD AND THE ATTENDANT MOISTURE PLUME NORTHEAST AND ACROSS
SE MICHIGAN SUNDAY NIGHT AND EARLY MONDAY. NORTHERN PORTIONS OF THE
FORECAST AREA MAY RECEIVE JUST A GLANCING SHOT OF PRECIPITATION...
WITH SOME SUGGESTION THAT THE BETTER MOISTURE TRANSPORT VECTOR
ANCHORED ON AN ATTENDANT LOW LEVEL JET CORE WILL FOCUS ACROSS THE
NORTHERN OHIO VALLEY. A WARMING THERMAL PROFILE WILL INTRODUCE
PTYPE CONCERNS DURING THE LATTER HALF OF THIS PERIOD
/MONDAY MORNING/...BUT WET BULB TEMPERATURES SECURELY BELOW FREEZING
AT ONSET WILL SUPPORT A PERIOD OF SNOWFALL OVERNIGHT. GOOD MOISTURE
QUALITY (PROGGED PW OF .75"...SPECIFIC HUMIDITY APPROACHING 3 G/KG)
INTO THE BACKGROUND FORCING INDICATES THAT THE PROGGED .2-.3" OF QPF
ACROSS THE SOUTH IS ATTAINABLE.
LOW LEVEL THERMAL RIDGE CARRYING 850 MB TEMPERATURES IN THE 6-8C
RANGE WILL SETTLE OVERHEAD IN THE WAKE OF THE EARLY DAY WARM FRONTAL
PASSAGE ON MONDAY. MID LEVEL MOISTURE STRIPS EAST BUT PLENTIFUL LOW
LEVEL MOISTURE AIDED BY THE SNOWMELT MAY PROMOTE A PERIOD OF
FOG/DRIZZLE. THIS WILL WARRANT JUST A CONSERVATIVE ADJUSTMENT
UPWARD IN HIGHS MONDAY DESPITE THE STRENGTHENING SOUTHWEST
GRADIENT/ADVECTIVE PROCESS. HIGHS INCHING TOWARD THE LOWER 40S
SOUTH. MODEL CONSENSUS PROVIDING A MORE PROGRESSIVE OUTLOOK WITH
THE EASTWARD TRANSLATION OF THE MEAN WESTERN CONUS TROUGH EARLY NEXT
WEEK...PERHAPS OWING TO THE PRESENCE OF A CONSIDERABLY FLATTER/LESS
AMPLIFIED FLOW DOWNSTREAM. THIS TRANSLATES INTO A FASTER ATTENDANT
LEAD FRONTAL PASSAGE SOMETIME ON TUESDAY...PROVIDING SOME DOUBT AS
TO THE DEGREE OF THE PRE-FRONTAL WARMUP. THIS FIRST ROUND OF COLD
AIR ADVECTION NOTHING EXTRAORDINARY...LIKELY SIMPLY EASING
TEMPERATURES BACK TO LATE JANUARY STANDARDS. THE NEXT ARCTIC PUSH
WILL BE TIED TO THE MORE PRONOUNCED TRAILING HEIGHT FALL REGION
PIVOTING THROUGH THE MEAN TROUGH...ARRIVING FOR THE END OF NEXT
WEEK.
MARINE...
AN ALBERTA CLIPPER SYSTEM WILL TRACK THROUGH THE GREAT LAKES REGION
TODAY AND TONIGHT. LIGHT SOUTHERLY WINDS TODAY WILL KEEP WAVE
HEIGHTS LOW THROUGH THE DAY. WINDS BEGIN TO INCREASE WITH GUSTS IN
THE 15 TO 20 KNOT RANGE AND EVENTUALLY SHIFTING TO THE
WEST-NORTHWEST ON SATURDAY BEHIND THE DEPARTING LOW. AT THIS TIME
NOT EXPECTING WAVES TO REACH SMALL CRAFT ADVISORY CRITERIA DURING
THE SATURDAY TIMEFRAME. WINDS EASE CONSIDERABLY SATURDAY NIGHT AS
HIGH PRESSURE TRACKS THROUGH THE REGION BEFORE PICKING UP SLIGHTLY
AND TURNING SOUTHERLY ON SUNDAY AS THE HIGH MOVES OFF TO THE EAST.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....BT
UPDATE.......BT
SHORT TERM...KURIMSKI
LONG TERM....MR
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1103 AM EST FRI JAN 25 2013
.UPDATE...
EXPECT LIGHT SNOW TO DIMINISH DURING THE AFTERNOON, ESPECIALLY IN
THE DETROIT AREA WHERE SYSTEM RELATIVE ISENTROPIC LIFT WILL BE ON
THE WANE. AN INFUSION OF DRY AIR WILL BE THE EVIDENCE OF MID
LEVEL THETA-E DISRUPTION WITH THE MODEST DRY SLOT POSSIBLY
REACHING AS FAR NORTH AS FLINT BUT LIKELY NOT AS FAR NORTH AS THE
TRI CITIES BEFORE THE UPPER LEVEL WAVE APPROACHES FROM WISCONSIN
TOWARD EVENING. EXPECT THIS WAVE TO RENEW ISENTROPIC LIFT AHEAD OF
ITS TRACK AND BRING A COMPONENT OF DYNAMIC FORCING THAT WILL HELP
BOOST COVERAGE OF LIGHT SNOW BUT AGAIN AFFECTING MAINLY THE TRI
CITIES AND NORTHERN THUMB DURING THE EVENING. THIS UPDATE WILL
ADDRESS THE DIMINISHING TREND IN THE DETROIT AREA WITH AFTERNOON
OBSERVATIONS UPSTREAM HELPING ADDRESS EVENING EXPECTATIONS WITH
THE AFTERNOON PACKAGE.
&&
.AVIATION...ISSUED 601 AM EST FRI JAN 25 2013
//DISCUSSION...
LOW PRESSURE SYSTEM TRACKING THROUGH THE NORTHERN GREAT LAKES WILL
ALLOW AN AREA OF SNOWFALL TO OVERSPREAD SOUTHEAST MICHIGAN TODAY.
POCKETS OF LIGHT SNOW WILL BEGIN TO EMERGE THIS MORNING AS THE LOWER
LAYERS GRADUALLY SATURATE. CONDITIONS WILL LOWER TO IFR/MVFR
16Z-20Z AS SNOWFALL INCREASES IN COVERAGE AND INTENSITY. MVFR
CONDITIONS WILL LINGER INTO THE EVENING AS LIGHT SNOW SHOWERS
CONTINUE ACROSS SOUTHEAST MICHIGAN. SNOWFALL AMOUNTS IN THE 1 TO 2
INCH RANGE ARE EXPECTED FROM THIS SYSTEM.
FOR DTW...A BRIEF BURST OF LIGHT SNOW REMAINS POSSIBLE THIS
MORNING...BUT UPSTREAM TRENDS SUGGEST THE GREATER POTENTIAL WILL
EXIST AROUND MIDDAY /16-20Z/.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN CEILINGS BELOW 5000 FEET THIS MORNING...HIGH
CONFIDENCE THIS AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 342 AM EST FRI JAN 25 2013
SHORT TERM...TODAY AND TONIGHT
AN APPROACHING CLIPPER SYSTEM WILL BRING ACCUMULATING SNOW TO
SOUTHEAST MICHIGAN TODAY AND TONIGHT. THE MAIN QUESTION REMAINS HOW
MUCH SNOW WILL FALL FROM THIS SYSTEM AS IT TRACKS THROUGH THE
CENTRAL GREAT LAKES. REGIONAL 00Z RAOB SOUNDINGS FROM KDTX/KAPX/KGRB
SHOW A VERY DRY AIRMASS BETWEEN 700 AND 500 MB WHICH NEEDS TO BE
OVERCOME BEFORE SNOWFALL CAN BEGIN IN EARNEST ACROSS SOUTHEAST
MICHIGAN. THE AMOUNT OF DRY AIR IS CONCERNING WITH RELATIVE HUMIDITY
VALUES FALLING TO AROUND 10 PERCENT IN THIS LAYER. HOWEVER AS KGRB
HAS PROVED THIS LAYER CAN BE OVERCOME AS NORTHEAST WISCONSIN IS
CURRENTLY GETTING ACCUMULATING SNOWFALL. WHILE THIS DRY AIR MAY NOT
PREVENT THE INEVITABLE...IT WILL PROBABLY DELAY THE ONSET OF THE
SNOWFALL WHICH THE NAM AND HRRR MODEL DEPICT RATHER WELL THIS RUN.
WHAT THIS SYSTEM LACKS IN MOISTURE IT MAKES UP FOR IN FORCING WITH
UPPER LEVEL DIVERGENCE IN THE LEFT EXIT REGION OF A STRONG 130 KNOT
JET DIVING SOUTH OVER THE SOUTHERN GREAT LAKES AND A STRONG MID
LEVEL SHORTWAVE CLEARLY EVIDENT ON WATER VAPOR IMAGERY CURRENTLY
SITUATED OVER THE UPPER MISSISSIPPI VALLEY. WHILE THESE DYNAMICS
WILL NOT MAKE UP FOR THE LACK OF MOISTURE...THEY WILL BE ABLE TO
TAKE ADVANTAGE OF THE MEAGER MOISTURE IN PLACE WITH AN ADDED BOOST
FROM LOW WATER CONTENT SNOW AS SNOW RATIOS OF 18 TO 19 TO 1 ARE
EXPECTED. WITH DRIER MODEL SOLUTIONS YIELDING QPF IN THE 0.05 TO
0.10 RANGE SNOWFALL AMOUNTS IN THE 1 TO 2 INCH RANGE SEEM REASONABLE
FROM THIS SYSTEM DURING THE TIME OF BEST FORCING BETWEEN 12Z AND 18Z.
THE HEADLINE QUESTION NEEDS TO BE ADDRESSED GIVEN THE BULK OF THE
SNOW IS EXPECTED IN A SHORT WINDOW OF A FEW HOURS WITH COLD SURFACE
TEMPERATURES IN THE SINGLE DIGITS UP TO THE MIDDLE TEENS EXPECTED TO
RENDER REGULAR ROAD SALT VERY INEFFICIENT FOR MELTING SNOW AND ICE
DURING THE MORNING HOURS. DESPITE THESE FACTORS THE DELAYED ONSET OF
THE SNOW WILL BE HELPFUL IN LIMITING THE EFFECT OF THESE CONDITIONS
ON THE MORNING COMMUTE. IN ADDITION UPSTREAM OBSERVATIONS ACROSS
WISCONSIN ARE NOT THAT IMPRESSIVE WITH VISIBILITIES GENERALLY AT OR
ABOVE 1 MILE. WITH THIS IN MIND PLAN TO HANDLE THE SNOW WITH SPECIAL
WEATHER STATEMENTS AS IT TRACKS EAST AND FORGO HEADLINES GIVEN MOST
OF THE IMPACT WILL BE AFTER THE MORNING COMMUTE.
ALTHOUGH THE MAIN FORCING FROM THE SYSTEM WILL BE EAST DURING THE
LATE AFTERNOON HOURS THE LOW ITSELF AND COLD FRONT WILL NOT MOVE
THROUGH UNTIL THE EVENING HOURS. THIS WILL MEAN LIGHT SNOW SHOWERS
WILL CONTINUE THROUGH THE OVERNIGHT HOURS...HOWEVER WITH THE BEST
FORCING AND MOISTURE OFF TO THE EAST ONLY A DUSTING OF ADDITIONAL
ACCUMULATION IS EXPECTED AFTER 18Z.
CLOUD COVER IS EXPECTED FOR MUCH OF THE DAYTIME HOURS...LIMITING
INCOMING SOLAR RADIATION. DESPITE SOUTHERLY SURFACE WINDS AHEAD OF
THE LOW...THE AIRMASS TO THE SOUTH IS NOT MUCH WARMER THAN THE ONE
CURRENTLY IN PLACE...OFFERING LITTLE TO NO WARM AIR ADVECTION TO
BOOST SURFACE TEMPERATURES. THEREFORE HIGHS ARE EXPECTED TO BE
IN THE LOW TO MID 20S THIS AFTERNOON. CONTINUED CLOUD COVER
OVERNIGHT AND NOT MUCH COLD AIR ADVECTION BEHIND THE COLD FRONT WILL
MEAN OVERNIGHT LOWS WILL GENERALLY BE IN THE 10 TO 15 DEGREE RANGE.
LONG TERM...SATURDAY THROUGH THURSDAY
BRIEF PERIOD OF DEEPER NORTHWEST FLOW TAKES HOLD ON SATURDAY IN THE
WAKE OF THE EXITING CLIPPER SYSTEM AND ALONG THE FRONT FACE OF THE
EXPANDING LOW TO MID LEVEL ANTICYCLONIC FLOW FILLING ACROSS THE UPPER
MS VALLEY. SHEAR AXIS EMBEDDED WITHIN THE WEAKENING CYCLONIC FLOW
WILL REMAIN DRAPED ACROSS THE REGION DURING THIS TIME. THIS BROAD
ASCENT WORKING INTO A DEEPENING CONVECTIVE LAYER AND A MOIST LAYER
THAT REMAINS FAVORABLY SATURATED WITH RESPECT TO ICE /-10 TO -14C
ISOTHERM/ WILL SUPPORT SOME VERY LIGHT SNOW SHOWER/FLURRY PRODUCTION
DURING THE DAY. IN ADDITION...BANDS OF LAKE DRIVEN SNOWFALL
ANCHORED ON THE LAKE HURON AGGREGATE TROUGH AXIS WILL TEND TO SHIFT
SOUTH-SOUTHEAST DOWN THE LONG FETCH IN RESPONSE TO INCREASING
PRESSURE AND A VEERING NORTHERLY WIND EMERGING ACROSS NORTHERN
PORTIONS OF THE LAKE. THE POTENTIAL DOES EXIST FOR THE WESTERN
PERIPHERY OF THIS BAND TO SWEEP ACROSS THE EASTERN THUMB SATURDAY
MORNING...BRINGING A QUICK SHOT OF ACCUMULATING SNOW. DRYING
NORTHERLY FLOW AND THE LOSS OF THE DIURNAL HEATING CYCLE WILL
SCATTER ANY LINGERING STRATOCU SATURDAY EVENING. HIGH CLOUDS WELL
IN ADVANCE OF THE NEXT SYSTEM MAY BE PROBLEMATIC FOR MAXIMIZING AN
OTHERWISE IDEAL SETUP FOR TEMPERATURES TO REALLY PLUMMET
/DIMINISHING GRADIENT...SNOW COVERAGE GROUND/. COLDEST LOCALES
CERTAINLY CAN MAKE A RUN TOWARD THE LOWER SINGLE DIGITS SUNDAY
MORNING GIVEN THE STRENGTH OF THE RESIDENT AIRMASS.
MID LEVEL CIRCULATION CURRENTLY ANCHORED OFF THE SOUTHERN CA
COASTLINE WILL RECEIVE THE NECESSARY NUDGE EASTWARD OVER THE WEEKEND
AS STRONG MID LEVEL ENERGY CRASHING INTO THE WEST COAST CARVES OUT
A DEEP LONG WAVE TROUGH. SHEARED WAVE EXPECTED TO EMBED WITHIN AN
INCREASING WEST-SOUTHWEST UPPER HEIGHT FIELD DOWNSTREAM...
TRANSLATING ACROSS SE MICHIGAN SUNDAY NIGHT. THIS PROCESS WILL
OCCUR COINCIDENT TO AND LIKELY ENHANCES A CORRIDOR OF WARM AIR
ADVECTION AND MOIST ISENTROPIC ASCENT THAT EMERGES IN INCREASING LOW
LEVEL SOUTHERLY FLOW. STRONG MODEL SUPPORT EXISTS IN DRIVING THIS
FORCING FIELD AND THE ATTENDANT MOISTURE PLUME NORTHEAST AND ACROSS
SE MICHIGAN SUNDAY NIGHT AND EARLY MONDAY. NORTHERN PORTIONS OF THE
FORECAST AREA MAY RECEIVE JUST A GLANCING SHOT OF PRECIPITATION...
WITH SOME SUGGESTION THAT THE BETTER MOISTURE TRANSPORT VECTOR
ANCHORED ON AN ATTENDANT LOW LEVEL JET CORE WILL FOCUS ACROSS THE
NORTHERN OHIO VALLEY. A WARMING THERMAL PROFILE WILL INTRODUCE
PTYPE CONCERNS DURING THE LATTER HALF OF THIS PERIOD
/MONDAY MORNING/...BUT WET BULB TEMPERATURES SECURELY BELOW FREEZING
AT ONSET WILL SUPPORT A PERIOD OF SNOWFALL OVERNIGHT. GOOD MOISTURE
QUALITY (PROGGED PW OF .75"...SPECIFIC HUMIDITY APPROACHING 3 G/KG)
INTO THE BACKGROUND FORCING INDICATES THAT THE PROGGED .2-.3" OF QPF
ACROSS THE SOUTH IS ATTAINABLE.
LOW LEVEL THERMAL RIDGE CARRYING 850 MB TEMPERATURES IN THE 6-8C
RANGE WILL SETTLE OVERHEAD IN THE WAKE OF THE EARLY DAY WARM FRONTAL
PASSAGE ON MONDAY. MID LEVEL MOISTURE STRIPS EAST BUT PLENTIFUL LOW
LEVEL MOISTURE AIDED BY THE SNOWMELT MAY PROMOTE A PERIOD OF
FOG/DRIZZLE. THIS WILL WARRANT JUST A CONSERVATIVE ADJUSTMENT
UPWARD IN HIGHS MONDAY DESPITE THE STRENGTHENING SOUTHWEST
GRADIENT/ADVECTIVE PROCESS. HIGHS INCHING TOWARD THE LOWER 40S
SOUTH. MODEL CONSENSUS PROVIDING A MORE PROGRESSIVE OUTLOOK WITH
THE EASTWARD TRANSLATION OF THE MEAN WESTERN CONUS TROUGH EARLY NEXT
WEEK...PERHAPS OWING TO THE PRESENCE OF A CONSIDERABLY FLATTER/LESS
AMPLIFIED FLOW DOWNSTREAM. THIS TRANSLATES INTO A FASTER ATTENDANT
LEAD FRONTAL PASSAGE SOMETIME ON TUESDAY...PROVIDING SOME DOUBT AS
TO THE DEGREE OF THE PRE-FRONTAL WARMUP. THIS FIRST ROUND OF COLD
AIR ADVECTION NOTHING EXTRAORDINARY...LIKELY SIMPLY EASING
TEMPERATURES BACK TO LATE JANUARY STANDARDS. THE NEXT ARCTIC PUSH
WILL BE TIED TO THE MORE PRONOUNCED TRAILING HEIGHT FALL REGION
PIVOTING THROUGH THE MEAN TROUGH...ARRIVING FOR THE END OF NEXT
WEEK.
MARINE...
AN ALBERTA CLIPPER SYSTEM WILL TRACK THROUGH THE GREAT LAKES REGION
TODAY AND TONIGHT. LIGHT SOUTHERLY WINDS TODAY WILL KEEP WAVE
HEIGHTS LOW THROUGH THE DAY. WINDS BEGIN TO INCREASE WITH GUSTS IN
THE 15 TO 20 KNOT RANGE AND EVENTUALLY SHIFTING TO THE
WEST-NORTHWEST ON SATURDAY BEHIND THE DEPARTING LOW. AT THIS TIME
NOT EXPECTING WAVES TO REACH SMALL CRAFT ADVISORY CRITERIA DURING
THE SATURDAY TIMEFRAME. WINDS EASE CONSIDERABLY SATURDAY NIGHT AS
HIGH PRESSURE TRACKS THROUGH THE REGION BEFORE PICKING UP SLIGHTLY
AND TURNING SOUTHERLY ON SUNDAY AS THE HIGH MOVES OFF TO THE EAST.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......BT
AVIATION.....MR
SHORT TERM...KURIMSKI
LONG TERM....MR
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
339 PM CST FRI JAN 25 2013
.SHORT TERM...TONIGHT THROUGH MONDAY.
THE FORECAST CONCERNS IN THE SHORT TERM WILL BE TEMPERATURES
BEHIND THE COLD FRONT TONIGHT...ONSET OF PRECIPITATION SATURDAY
NIGHT AND SUNDAY AND PRECIPITATION TYPE...AND PRECIPITATION AND
PRECIP TYPE WITH MONDAY SYSTEM.
TEMPERATURES AHEAD OF A COLD FRONT HAVE WARMED INTO THE 40S AND
50S...HOWEVER MUCH COLDER AIR LIES TO THE NORTH WITH TEENS AS FAR
SOUTH AS HURON SD. THIS COLD FRONT WILL PUSH THROUGH PARTS OF THE
FORECAST AREA. THE RAP SEEMS TO HAVE A GOOD HANDLE ON THE COLD
AIR. THE BRUNT OF THE COLD AIR AND SUB-ZERO READINGS WILL HOLD
OVER IN SD AND MN...TEMPERATURES IN THE TEENS (POSSIBLY SINGLE
DIGITS NEAR WAYNE AND MAPLETON) SHOULD MAKE IT INTO THE NORTHEAST
HALF OF THE FORECAST AREA WITH 20S FOR THE SOUTH. SOME CIRRUS
TONIGHT ALONG WITH SOME PATCHY LOW AND MID CLOUDS NORTH. SURFACE
WINDS BECOME LIGHT SOUTHEAST TONIGHT AND HAVE A DECENT GRADIENT IN
DEWPOINTS AND TEMPERATURES FROM MAPLETON TO THE SOUTHWEST TOWARD
FAIRBURY.
WITH THE STORM SYSTEM FOR THE WEEKEND STILL OFF THE CA/MEXICAN
COAST...THERE COULD BE SAMPLING ISSUES AND OPENS THE FORECAST UP
TO TIMING CHANGES. FOR NOW...THERE IS DECENT AGREEMENT BETWEEN THE
SHORT RANGE MODELS THAT THE SHORTWAVE TROF WILL MOVE THROUGH THE
SOUTHWEST U.S. SATURDAY WITH SURFACE LOW PRESSURE OVER THE
WESTERN PLAINS AND A STRENGTHENING LOW LEVEL JET OVER THE PLAINS.
LIFT ASSOCIATED WITH THE TROF AND WARM AIR ADVECTION BRING
INCREASING CLOUDS AND SPREAD PRECIPITATION FROM THE SOUTHWEST U.S.
INTO THE PLAINS. THE ONSET OF THE PRECIPITATION SHOULD MAINLY BE
AFTER MIDNIGHT...ALTHOUGH COULD EASILY START IN THE EVENING TOWARD
THE KANSAS/NEBRASKA BORDER...AND MOVE NORTHEAST ACROSS EASTERN
NEBRASKA AND IOWA DURING THE DAY SUNDAY. THE PRECIPITATION COULD
START OUT AS FREEZING RAIN WHERE TEMPERATURES ARE AT OR BELOW ZERO
(MAINLY NORTH OF A NORFOLK TO TEKAMAH TO OAKLAND)...HOWEVER HAVE
THE BULK OF THE PRECIPITATION STARTING OUT AS RAIN. THE BEST LIFT
APPEARS FROM AROUND 10Z TO 20Z SUNDAY. THE SOUTHWEST FLOW ALOFT
WILL BRING HIGH PRECIP WATER VALUES TO THE REGION... .5 INCH TO 1
INCH. FOR NOW A BEST ESTIMATE OF AMOUNTS WITH THE STORM IS LESS
THAN A TENTH OF AN INCH OF WATER AT NORFOLK NORTHWESTWARD...A
QUARTER OF AN INCH OR SO OMAHA TO LINCOLN AND A HALF AN INCH
TOWARD FALLS CITY. HIGHS SATURDAY AND SUNDAY SHOULD BE IN THE 30S
AND 40S. A FEW LOCATIONS MAY HIT THE 50S SOUTH.
THE MAIN MID LEVEL TROF IS STILL TO THE WEST AND THE LOW LEVEL
MOISTURE DOES NOT GET SCOURED OUT. WITH THE WEAK FLOW DO HAVE SOME
FOG MENTIONED AND WILL HAVE TO WATCH FOR FREEZING FOG CONDITIONS.
A STRONGER PUSH OF COLD AIR OCCURS MONDAY. MAY SEE SOME LIGHT RAIN
OR DRIZZLE FOR PARTS OF THE AREA MONDAY AND BEHIND THE H85 COLD
FRONT A BAND OF SNOW MAY DEVELOP IN NORTHEAST NEBRASKA.
ZAPOTOCNY
&&
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY.
THE MAIN STORY IN THE EXTENDED IS STILL THE LARGE-SCALE TROUGH TO
MOVE THROUGH THE AREA TUESDAY AND THEN SOME SEASONABLY CHILLY AIR
FOR THE REST OF THE PERIOD. THE GLOBAL MODELS ARE STILL SHOWING
SIGNIFICANT RUN TO RUN FLUCTUATION IN REGARDS TO THE TROUGH AS IT
CROSSES THE CENTRAL CONUS. THE 12Z ECMWF HAS TRENDED TOWARD A MORE
CONSISTENT GFS/GEM WITH REGARDS TO THE INTERACTION OF THE NRN AND
SRN STREAM SHORTWAVE IN THE LARGER MEAN TROUGH BUT STILL THE MODELS
DIFFER ON THE SENSIBLE WEATHER THAT WILL MOVE THE CWA. THERE IS A
GOOD DEAL OF CONFIDENCE THAT A CDFNT WILL MOVE THROUGH THE FA ON MON
NIGHT AS LOW PRESSURE MOVES THROUGH KS/MO AND STARTS TO DEEPEN OVER
THE GREAT LAKES. MID LEVEL FRONTOGENESIS BEHIND THE FNT COULD LEAD
TO A LITTLE -RA/SN MIX ON MON NIGHT INTO TUE MORNING AS THIS SYSTEM
MOVES THROUGH...BUT THE THREAT FOR WIDESPREAD OR SIGNIFICANT PRECIP
LOOKS VERY LOW ATTM. WE WILL MAINTAIN SOME CHC/SCHC POPS FOR THESE
TWO PERIODS. OTHERWISE SURFACE HIGH PRESSURE WILL BUILD SOUTH INTO
THE CENTRAL AND NORTHERN PLAINS FOR TUE NIGHT THRU FRI WITH DRY
WEATHER THESE PERIODS. THE DEGREE OF COLD AIR WILL LIKELY ONCE AGAIN
BE MODIFIED BY THE LACK OF SNOW COVER ACROSS THE REGION...BUT
OVERALL BELOW NORMAL TEMPERATURES APPEAR LIKELY.
BOUSTEAD
$
.AVIATION...
12Z TAFS FOR KOMA...KLNK...KOFK.
VFR CONDITIONS WILL PREVAIL THRU THE FCST PD.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1152 AM CST FRI JAN 25 2013
.DISCUSSION.../ISSUED AT 1140 AM CST/
COLD FRONT HAS PUSHED INTO NORTHEAST PORTIONS OF THE CWA AS OF 17Z
AND STARTING TO SEE EFFECTS WITH TEMPERATURES FALLING OFF FROM
BROOKINGS INTO MUCH OF NORTHERN COUNTIES OF SOUTHWEST MN OVER THE
PAST HOUR OR TWO. EXPECT THIS TREND TO CONTINUE SOUTHWARD THROUGH
THE AFTERNOON...ESPECIALLY EAST OF THE JAMES RIVER...THOUGH AREAS
IMMEDIATELY BEHIND THE FRONT WILL LIKELY SEE TEMPERATURES BUMP UP
WITH INITIAL STRONG MIXING BEFORE COLD ADVECTION TAKES OVER. THIS
HAS RESULTED IN SOME TRICKY HOURLY TEMPERATURE FORECASTING THUS FAR
THIS MORNING AS MODELS HAVING A HARD TIME CAPTURING DEGREE OF THIS
INITIAL WARMING. HAVE MADE SOME ADJUSTMENTS TO HOURLY TEMPS/HIGHS SO
FAR AND MORE LIKELY OVER THE NEXT COUPLE OF HOURS.
ALSO ADJUSTED SKY GRIDS EARLIER TO CAPTURE NARROW BAND OF STRATUS
DROPPING SOUTH ALONG/JUST AHEAD OF THE COLD FRONT. RAP SHOWS THIS
BAND MOVING SLOWLY SOUTH BUT ALSO THINNING/DISSIPATING AS IT RUNS
INTO SOME DRIER AIR...SO HAVE THUS FAR OPTED TO KEEP IT NORTH OF THE
MISSOURI VALLEY...WHILE GRADUALLY DIMINISHING THE COVERAGE THROUGH
THE AFTERNOON. WILL LIKELY MAKE FURTHER MINOR ADJUSTMENTS TO THIS AS
WELL. POTENTIAL FOR A FEW FLURRIES ON THE BACK SIDE OF THE STRATUS
AS TEMPERATURES IN CLOUD LAYER COOL BELOW -10C. WINDOW FOR THIS
LOOKS RELATIVELY NARROW AND HAVE NOT ADDED TO THE GRIDS JUST YET...
BUT WILL MONITOR CLOSELY. STRONGER WINDS BEHIND THE FRONT ALSO
KICKING UP A LITTLE BLOWING SNOW WITH PIPESTONE/SLAYTON REPORTING
SOME 4-5SM VISIBILITY WITHIN THE LAST HOUR. OVERALL SNOWPACK IS
PRETTY SOLID THOUGH...SO EXPECT EFFECTS OF THIS TO LESSEN...WITH
MORE OF A DRIFTING THAN BLOWING SNOW POTENTIAL IN HIGHER ELEVATIONS.
UPDATED GRIDS HAVE BEEN SENT...AND WILL GET UPDATED ZFP/PFM OUT
SHORTLY.
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
NARROWING BAND OF MVFR STRATUS CONTINUES TO DROP SOUTHWARD JUST
AHEAD OF COLD FRONT PUSHING INTO THE FORECAST AREA. CLOUD BAND
ENCOUNTERING DRIER AIR AS IT TRIES TO PUSH TOWARD THE MISSOURI RIVER
VALLEY...SO EXPECT KSUX TO REMAIN VFR THROUGH THE PERIOD. KFSD/KHON
ON THE OTHER HAND...WILL SEE MVFR CONDITIONS FOR FIRST 2-4 HOURS OF
THE TAF PERIOD...POTENTIALLY LONGER IN KHON AS WESTERN EXTENT OF THE
STRATUS BAND WITHIN LOW LEVEL RIDGE AXIS IS MAKING LESS SOUTHWARD
PROGRESS THAN AREAS FARTHER EAST. HOWEVER AT THIS TIME STILL EXPECT
BOTH KFSD AND KHON BECOME VFR BY 26/00Z. DEEPER MIXING WITH INITIAL
SURGE OF COLD ADVECTION BEHIND THE FRONT ENHANCING WIND GUSTS EAST
OF THE JAMES RIVER...AND GUSTS OF 25-30KTS LIKELY EXPANDING FROM
SOUTHWEST MN INTO NORTHWEST IOWA THROUGH THE EARLY-MID AFTERNOON.
STRONGEST OF GUSTS EXPECTED TO REMAIN EAST OF KFSD/KSUX...THOUGH
KFSD MAY SEE SOME BRIEF GUSTS TO AROUND 25KTS THROUGH 19-20Z.
&&
.PREV DISCUSSION.../ISSUED AT 310 AM CST/
COLD FRONT WILL PUSH SOUTHEAST ACROSS CWA THIS MORNING...WITH MAIN
BRUNT OF COOLING OVER NORTHEAST CWA WHERE TEMPERATURES WILL AGAIN BE
BELOW NORMAL...WHILE SOUTHWEST CWA MIXES OUT TO ABOVE NORMAL.
STRATUS DROPPING SOUTHEAST OUT OF NORTHEAST SD WILL SPREAD INTO
SOUTHWEST MN THIS MORNING...SO EXPECT MOSTLY CLOUDY SKIES THERE THIS
MORNING...WITH MOSTLY SUNNY SKIES ELSEWHERE. WILL BE A BIT BREEZY
TODAY WITH NORTHWEST WINDS GUSTING TO 25 MPH AT TIMES.
WIND WILL DROP OFF THIS EVENING...AND WILL ALLOW FOR ANOTHER COLD
NIGHT...ESPECIALLY NORTHEAST WHERE LOWS WILL DROP BELOW ZERO. AGAIN
WILL SEE A WIDE RANGE IN TEMPERATURES...WITH FAR SOUTHWEST CWA IN
THE TEENS FOR LOWS.
WARMER AIR WILL SPREAD NORTHEAST ACROSS CWA ON SATURDAY AS HIGH
PRESSURE MOVES OFF INTO THE GREAT LAKES REGION. WILL SEE SOME
INCREASE IN CLOUD COVER DURING THE DAY...ALONG WITH INCREASING
SOUTHEAST WINDS. HIGHS WILL VARY FROM THE LOWER 20S OVER SOUTHWEST
MN...TO THE LOWER 40S OVER GREGORY COUNTY.
WAVE WILL PUSH EAST ACROSS THE CENTRAL PLAINS LATE SATURDAY NIGHT
AND SUNDAY. GFS CONTINUES TO BE THE FURTHEST NORTH WITH THIS FEATURE
WHILE BOTH ECMWF AND NAM KEEP IT WELL TO THE SOUTHEAST. IN
FACT...ECMWF MUCH WEAKER AND ALMOST NON EXISTENT WITH WAVE. SO WILL
NOT RAISE POPS AND WILL DECREASE A BIT ACROSS NORTHWEST IOWA. WITH
WARMER AIR ALOFT OVER CWA...ANY PRECIPITATION THAT DOES OCCUR WILL
EITHER BE LIGHT RAIN OR LIGHT FREEZING RAIN.
THE MILD TEMPERATURES WILL PERSIST INTO MONDAY...BUT STRATUS MAY
SPREAD NORTH INTO CWA AS WAVE PASSES BY TO THE SOUTH ON SUNDAY. SO
THAT COULD HAVE AN EFFECT ON TEMPERATURES. STILL WILL SEE HIGHS 5 TO
10 DEGREES ABOVE NORMAL ACROSS CWA BOTH SUNDAY AND MONDAY.
MODELS HAVE SHIFTED CONSIDERABLY FOR SYSTEM MONDAY NIGHT AND
TUESDAY...WITH MODELS MUCH WEAKER AND ONLY LIGHT PRECIPITATION AT
BEST. TIMING A BIT DIFFERENT WITH GFS MUCH QUICKER AND MUCH COLDER
ON TUESDAY...WHILE ECMWF SLOWER AND WARMER. FOR NOW WILL TEND TO A
CONSENSUS BLEND WHICH IS SLOWER THAN GFS. COLDER AIR WILL SPREAD
SOUTHEAST ACROSS CWA TUESDAY NIGHT AND PERSIST INTO THURSDAY.
TEMPERATURES SHOULD AGAIN BE BELOW NORMAL WEDNESDAY AND THURSDAY AS
ARCTIC HIGH SETTLES SOUTH.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
MN...NONE.
NE...NONE.
SD...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1156 AM CST FRI JAN 25 2013
.AVIATION...
SW FLOW THIS AFTERNOON WITH SOME GUSTS NEAR 20 KTS POSSIBLE.
PATCHY MVFR CIGS SHOULD RISE TO NEAR 3000FT BY 20Z AND SCATTER
OUT. GRADIENT RELAXES LATE THIS AFTERNOON AS LLJ OVER NETX PULLS
AWAY AND WINDS RESPOND TO ABUNDANT HEATING OVER THE SOUTHERN HALF
OF TX...COLD FRONT STALLING NEAR LHB-DKR-OCH. BY EARLY EVENING
EXPECT WINDS TO BACK TO THE SOUTH AND SOUTH-SOUTHEAST WHICH MAY
SET THE STAGE FOR A NIGHT OF FOG OVER MUCH OF THE TERMINALS...EVEN
WITHOUT THE FOG EXPECT IFR CIGS. VISBY ESPECIALLY FOR HOU
SOUTHWARD SHOULD DROP INTO THE 1/2 TO 0 RANGE. IMPROVEMENT WILL BE
SLOW TO VERY SLOW AFTER 15Z SATURDAY WITH IFR CONDITIONS LINGERING
THROUGH 18Z. IF THE RAP IS CORRECT THEN MORE BACKED WINDS WILL
PREVAIL AFTER 03Z AND FOG COULD REACH FARTHER INLAND. HAVE LOWER
FLIGHT CATEGORY FORECASTS BUT NOT AS PESSIMISTIC AS RAP ATTM.
45
&&
.PREV DISCUSSION... /ISSUED 1023 AM CST FRI JAN 25 2013/
DISCUSSION...
THE COLD FRONT THAT HAS PUSHED THROUGH MUCH OF NORTH TEXAS APPEARS
TO BE STALLING OUT JUST NORTH OF OUR REGION THIS MORNING AND IS
NOT EXPECTED TO MAKE MUCH MORE PROGRESS TO THE SOUTH. WITH CLOUDS
SCATTERING OUT ACROSS SOUTHEAST TEXAS AND TEMPERATURES AT OR ABOVE
WHERE THEY WERE THIS TIME YESTERDAY WE SHOULD SEE MOST LOCATIONS
REACH THE UPPER 70S TO NEAR 80 DEGREES THIS AFTERNOON. CURRENT
FORECAST IS IN GOOD SHAPE AND NO UPDATES PLANNED THIS MORNING. 38
MARINE...
SOUTHERLY FLOW CONTINUING...WELL OFFSHORE WINDS NEAR 15 KNOTS THIS
MORNING SHOULD GRADUALLY COME DOWN THIS AFTERNOON AND EVENING.
BUMPED UP SEAS A FOOT. SEA FOG STILL LOOKS LIKE A GOOD BET GIVEN THE
LIGHTER MORE BACKED WINDS AND THE ALREADY HIGH DEWPOINTS IN THE
LOWER TO MID 60S.
45
AVIATION...
LOW CIGS ON THE RISE BUT EXPECT THE CIGS TO HOLD IN THE MVFR RANGE
THRU 18Z AND THEN MIX OUT THIS AFTERNOON. EXPECT MORE FOG TONIGHT
AND FROM THE COAST AND PROBABLY UP THROUGH UTS.
45
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 79 61 77 59 75 / 0 10 10 10 10
HOUSTON (IAH) 80 61 79 60 77 / 0 10 10 10 10
GALVESTON (GLS) 73 63 72 62 71 / 0 10 10 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...38
AVIATION/MARINE...45
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
345 PM CST FRI JAN 25 2013
.SHORT TERM...
TONIGHT...FORECAST CONFIDENCE...MEDIUM TO HIGH.
ONGOING LIGHT SNOW IN THE EAST DUE TO PERSISTENT Q-VECTOR
CONVERGENCE AND MID LEVEL OMEGA OVER THE REGION AND LOW LEVEL
MOISTURE IN THE DENDRITE GROWTH ZONE PER RAP SOUNDINGS. THE DRY SLOT
BETWEEN THE SOUTHWEST WINDS AND THE COLD FRONT IS GRADUALLY CLOSING
UP AS THE COLD FRONT IS CATCHING UP. IT HAS PROGRESSED INTO PORTIONS
OF SOUTH CENTRAL WI INCLUDING THE DELLS AS OF 330 PM. THERE IS AN
AREA OF SNOW SHOWERS WITH INCREASING REFLECTIVITY NEAR MADISON WITH
WEST WINDS...BASICALLY ALIGNED WITH A PRE-FRONTAL TROUGH. THIS WILL
CONTINUE TO MOVE INTO SOUTHEAST WI THROUGH 00Z. THE LOW LEVEL LAPSE
RATES ARE INCREASING DUE TO DIFFERENTIAL VORTICITY ADVECTION AND
THIS IS CREATING A MORE CONVECTIVE LOOK TO THE SNOW SHOWERS ON
RADAR.
THE COLD FRONT CHARACTERIZED BY THE SURFACE WIND SHIFT TO WNW
ALREADY AT THE DELLS WILL MAKE ITS WAY ACROSS SOUTHERN WI THROUGH
03Z THIS EVENING. A TWO HOUR PERIOD OF CONVECTIVE-LOOKING SNOW
SHOWERS IS EXPECTED AT EACH SITE. HIGHER POPS IN THE NORTHERN
FORECAST AREA AND LOWER POPS ALONG THE ILLINOIS BORDER. THESE SHOULD
EXIT MILWAUKEE AND SHEBOYGAN BY 03Z. A QUICK HALF INCH OF SNOW IS
NOT OUT OF THE QUESTION...ALONG WITH BRIEF PERIODS OF LOWER
VISIBILITY WITH SOME GUSTY NORTHWEST WINDS.
SKIES SHOULD CLEAR FAIRLY QUICKLY FROM WEST TO EAST DURING THE
EVENING AS LOW PRESSURE EXITS AND HIGH PRESSURE BUILDS INTO THE
REGION. WINDS WILL DECREASE OVERNIGHT AS WELL...AND TEMPERATURES
WILL DROP INTO THE SINGLE DIGITS INLAND FROM THE LAKE.
SATURDAY...FORECAST CONFIDENCE HIGH.
IT WILL BE A QUIET WEATHER DAY WITH HIGH PRESSURE OVERHEAD. PLENTY
OF SUNSHINE IS EXPECTED IN THE MORNING. THEN HIGH CLOUDS WILL BEGIN
TO SPREAD INTO SOUTHERN WI LATE IN THE AFTERNOON. HIGHS EXPECTED TO
WARM INTO THE LOWER 20S.
SATURDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE MEDIUM
SLY WINDS WILL DEVELOP SAT NT AS A SHORTWAVE TROUGH MOVES INTO THE
CENTRAL PLAINS WITH LEE SIDE CYCLOGENESIS. MID LEVEL WARM ADVECTION
WELL AHEAD OF THE SHORTWAVE WILL BRING SCT-BKN MID LEVEL CLOUDS
FOR SAT NT WITH LOW TEMPS COOLING ONLY INTO THE TEENS.
THE SHORTWAVE TROUGH WILL THEN REACH THE MS RIVER BY 00Z MON WITH
A WAVE OF LOW PRESSURE REACHING IA. THE WAVE OF LOW PRESSURE WILL
THEN APPROXIMATELY MOVE ACROSS THE WI/IL BORDER SUN NT INTO MON.
ORGANIZED WARM ADVECTION AND FRONTOGENESIS IN THE 850-600 MB LAYER
WILL SHIFT NEWD THROUGH SRN WI SUN AFTERNOON AND NIGHT WITH PWS
INCREASING TO NEARLY 0.80 INCHES. A WARM LAYER ALOFT OF 2-4C WILL
MOVE NWD ACROSS SRN WI DURING THIS TIME WHILE SFC TEMPS REMAIN
BELOW FREEZING FOR SOME TIME. THUS SEE THE PCPN BEGINNING AS
SNOW...THEN SNOW AND SLEET...AND POSSIBLY TRANSITIONING TO ALL
FREEZING RAIN IN THE SRN HALF OF THE CWA. A MODELS CONSENSUS OF
QPF FOR SUN AND SUN NT RANGES FROM 0.35-0.45 INCHES ACROSS THE CWA.
THIS CONVERTS TO A COUPLE INCHES OF SNOW IN THE NRN CWA TO UNDER
AN INCH IN THE SOUTH. ICE ACCUMS RANGE FROM 0.10-0.24 INCHES WITH
THE LESSER AMOUNTS IN THE NORTH AND FAR EAST WHERE EITHER MORE
SNOW WILL OCCUR OR TEMPS WILL BE MILDER. ICE ACCUM FORECAST IS
DIFFICULT SUN NT SINCE TEMPS WILL BE RISING TO OR ABOVE FREEZING.
CURRENTLY THINK THIS IS AN ADVISORY SITUATION BUT WILL ISSUE A
SPECIAL WEATHER STATEMENT FOR NOW.
.LONG TERM...FORECAST CONFIDENCE LOW TO MEDIUM
A FAIRLY DEEP UPPER TROUGH WILL TRACK EAST ACROSS THE COUNTRY NEXT
WEEK BUT THE DETAILS OF TIMING AND CYCLOGENESIS ARE UNKNOWN DUE TO
A LARGE MODEL SPREAD. MILDER TEMPS HOWEVER SHOULD BE OVER THE AREA
MON-TUE WITH A STRONG COLD FRONT ARRIVING TUE NT OR WED. THERE
WILL BE CHANCES OF RAIN...THEN SNOW DURING THIS TIME. BRISK NWLY
WINDS AND COLD ADVECTION TO THEN PREVAIL THROUGH THU FOLLOWED BY
POLAR HIGH PRESSURE FOR FRIDAY.
&&
.AVIATION/00Z TAFS/...
AREA OF VFR CIGS WITH WEST WINDS AND SNOW SHOWERS OVER SOUTH CENTRAL
WI IS MOVING INTO SOUTHEAST WI THIS AFTERNOON. A COLD FRONT THAT
JUST CLEARED THE DELLS AROUND 3 PM WITH A WIND SHIFT TO NORTHWEST
WILL HIT MSN AROUND 4PM AND MKE JUST AFTER 00Z EARLY THIS EVENING.
EXPECTING ABOUT A 2 HOUR PERIOD OF SNOW SHOWERS THAT COULD BRING THE
VSBY DOWN TO AROUND 2 MILES FOR A SHORT PERIOD OF TIME WITH THE COLD
FRONT.
THEN WINDS WILL GRADUALLY DIE DOWN THROUGH THE NIGHT AND SKIES ARE
EXPECTED TO CLEAR. CLEAR SKIES WILL GIVE WAY TO SOME HIGH CLOUDS
SATURDAY AFTERNOON WITH SOUTH WINDS DEVELOPING LATE IN THE DAY.
&&
.MARINE...NORTHWEST WINDS BEHIND A COLD FRONT WILL INCREASE TO
MARGINAL SMALL CRAFT ADVISORY CONDITIONS EARLY THIS EVENING AND
PERSIST OVERNIGHT. WINDS WILL DIMINISH SATURDAY MORNING AS HIGH
PRESSURE BUILDS INTO THE REGION. SMALL CRAFT ADVY IN EFFECT 6PM THIS
EVENING TO 6AM SAT MORNING.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 AM CST SATURDAY FOR LMZ643>646.
&&
$$
TONIGHT/SATURDAY AND AVIATION/MARINE...MRC
SATURDAY NIGHT THROUGH FRIDAY...GEHRING