Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/26/13

AREA FORECAST DISCUSSION

NWS DENVER/BOULDER CO

 850 PM MST FRI JAN 25 2013

.UPDATE...NO BIG CHANGES TO THE EVENING FORECAST OTHER THAN
DECREASING THE AMOUNT OF CLOUD COVER ACROSS THE PLAINS OVERNIGHT.
MOISTURE OVER THE MOUNTAINS WILL BE GRADUALLY INCREASING
OVERNIGHT...SO THE FORECAST OF A SLIGHT CHANCE OR CHANCE OF SNOW
SHOWERS LOOKS OKAY FOR NOW. THE VIEW FROM A COUPLE WEB CAMS IN THE
MOUNTAINS SHOWS THAT ROADS ARE WET IN SOME PLACES...SO A FEW LIGHT
SNOW SHOWERS MAY ALREADY BE DRIFTING AROUND UP THERE.

&&

.AVIATION...NO AVIATION IMPACTS ARE EXPECTED THROUGH TONIGHT.
WINDS WILL GRADUALLY BECOME MORE SOUTHERLY OVER THE NEXT COUPLE
HOURS AND REMAIN OUT OF THE SOUTH THROUGH MUCH OF TOMORROW. ONLY
HIGH CLOUDS ARE EXPECTED ON THE PLAINS TOMORROW...BUT MOUNTAIN
OBSCURATIONS SHOULD BE COMMON.

&&

.PREV DISCUSSION... /ISSUED 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...DANKERS
LONG TERM....99
AVIATION...DANKERS



AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 139 PM CST THU JAN 24 2013

.MESOSCALE DISCUSSION...
955 AM CST

THE LAKE EFFECT SNOW ADVISORY FOR LAKE COUNTY INDIANA WILL LIKELY
BE CANCELLED SHORTLY AS THE LAKE EFFECT SNOW BAND SHIFTS
WESTWARD. MINOR ACCUMULATIONS IN EASTERN COOK COUNTY...ESPECIALLY
SOUTHEAST...ARE STILL ON TRACK.

VISIBLE SATELLITE AND RADAR MOSAIC TOGETHER SHOW AN IMPRESSIVELY
LENGTHY SNOW SHOWER BAND FROM NNE TO SSW ACROSS LAKE MI. WITHIN
THIS HAVE BEEN SOME EMBEDDED CIRCULATIONS AS SEEN ON RADAR...AND
THESE HAVE BEEN NEAR OR MOVED ONSHORE AND LIKELY BEEN RESPONSIBLE
FOR SOME OF THE VERY HEAVY SNOWFALL BURSTS SEEN ON WEBCAMS AND
RELAYED TO THE NWS. THE OVERALL CONVERGENCE CONTINUES TO BE STRONG
MID-LAKE PER STREAMLINE ANALYSIS AND JUST THE LOOK OF THE CLOUDS
ON VISBILE. TOWARD THE NE IL SHORE THIS HAS APPEARED TO WEAKEN
SOME...ALTHOUGH THERE ARE STILL SIGNS OF SMALL SCALE CIRCULATIONS
IN THE REFLECTIVITY. THE 12Z 850MB AND 925MB TEMPERATURES ARE
BOTH AROUND -20C PER MORNING RAOBS AIDING IN SHARP LAPSE RATES OF
AIR FROM THE LAKE. A MODIFIED 14Z MDW AMDAR SOUNDING FOR ESTIMATED
LAKE TEMPERATURES AND MODIFIED DEW POINTS INDICATING NEARLY 500
J/KG OF LAKE INDUCED CAPE. RAP GUIDANCE SHIFTS AND WEAKENS THE
FOCUS OF THE BOUNDARY LAYER CONVERGENCE NORTHWEST DICTATED BY THE
AMBIENT FLOW TURNING MORE ESE THIS AFTERNOON. SO THINKING THAT
WHILE SNOW SHOWERS MAY NOT BE AS CONCENTRATED INTO COOK AND LAKE
COUNTIES IL AS THEY WERE IN NORTHWEST IN EARLIER...THE INSTABILITY
WILL HELP TO DRIVE STRONGER SHOWERS AT TIMES. ONE TO TWO INCH
AMOUNTS ARE LIKELY IN ANY OF THE LAKESHORE AREAS THAT GET UNDER
ONE OF THESE BURSTS EVEN IF FOR JUST A HALF HOUR.

MTF

&&

.DISCUSSION...
358 AM CST

A LOT GOING ON THROUGH THE NEXT 7 DAYS...

TODAY...

LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z.

HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR
NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO
A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS
THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE
BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF
PRODUCING SOME ACCUMULATING SNOW.

HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE
SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE
NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY
SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC
FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER
THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN
FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE
BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST
COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC
PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW
LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR
LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST
RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH
AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS
IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH
PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST
SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL
WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF
PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW
LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED.

TONIGHT THROUGH FRIDAY...

HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO
FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST.

GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE
TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST
ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON.
WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL
ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY
STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY
FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS
DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT
THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH
TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT
900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD
OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL
RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY
FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH
LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY
LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID
RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH
WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS
THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY
BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER
LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW
BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800
MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C
RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED
FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH
AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND
APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS
BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY
NIGHT.

SUNDAY THROUGH WEDNESDAY...

HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE
SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE
RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO
TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55
RFD.

MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE
PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST
OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER
RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE
TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING
FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS
DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN
FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY
DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT
ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT
SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT
INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB
LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL
DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB
THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH
850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS
OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE
PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY
AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT
PERIOD OF SLEET/FREEZING RAIN.

00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER
BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER
SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN.
THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN
DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID-
LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS
OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL
TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY...
THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF
THROUGH THE DAY.

FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS
BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT
EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH
EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT
WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY.
WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS
ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH
PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING
AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE
CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF
THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S
DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT
WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A
MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE
LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT
ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE
THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING
500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY
AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD
SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* SNOW DEVELOPING LATE TONIGHT AND CONTINUING INTO FRIDAY
  MORNING...IFR OR LOWER VIS AND LOW MVFR CIGS POSSIBLE.

* GUSTY WEST-NORTHWEST WINDS LATE FRIDAY AFTERNOON/EVENING.

KJB

//DISCUSSION...UPDATED 18Z...

THE REMNANT LAKE EFFECT SNOW SHOWERS ARE CURRENTLY MOVING ACROSS
ORD...BUT THE LINE HAS WEAKENED CONSIDERABLY...AND IS NOT RESULTING
IN ANY SIGNIFICANT RESTRICTIONS TO THE VISIBILITIES. THIS ACTIVITY
WILL QUICKLY MOVE OUT OF THE AREA BY 1 PM THIS AFTERNOON.

THE WINDS WILL GRADUALLY BECOME EASTERLY AND THEN SOUTHEASTERLY
THROUGH THE AFTERNOON AS HIGH PRESSURE DROPS SOUTHEASTWARD ACROSS
LOWER MICHIGAN.

OUR NEXT STORM SYSTEM WILL MOVE ACROSS THE REGION LATE TONIGHT AND
INTO FRIDAY MORNING. SNOW IS EXPECTED TO DEVELOP AFTER 1 AM NEAR
KRFD AND AFTER 3 AM AT THE EASTERN TERMINALS. THERE WILL BE SOME DRY
AIR TO OVERCOME INITIALLY. HOWEVER...WITH THE DECENT ISENTROPIC
ASCENT AND THE INCREASINGLY SOUTHERLY FLOW...I FEEL THAT THIS DRY
AIR WILL BE OVERCOME FAIRLY QUICKLY. MODEL BUFFER SOUNDINGS INDICATE
SOME DECENT MID LEVEL LAPSE RATES EARLY FRIDAY MORNING...DURING THE
HEIGHT OF THE EVENT. THIS COULD LEAD TO A PERIOD OF SNOW WITH
VISIBILITIES POSSIBLY DROPPING DOWN AROUND 1 MILE FOR A FEW HOURS
TOMORROW MORNING. THE SNOW SHOULD ABATE LATER IN THE MORNING AS THE
MID LEVEL WAVE MOVES EAST OF THE AREA AND DRIER AIR BUILDS INTO THE
MID LEVELS.

A SURFACE LOW WILL BE MOVING ACROSS THE UPPER GREAT LAKES REGION
WITH THE WARM SECTOR BRIEFLY MOVING ACROSS THE AREA FRIDAY EARLY
AFTERNOON BEFORE ANOTHER COLD FRONT COMES PUSHING ACROSS THE AREA BY
VERY LATE AFTERNOON OR EARLY FRIDAY EVENING. IT IS POSSIBLE THAT
SOME ADDITIONAL SNOW SHOWERS COULD DEVELOP DURING THIS TIME AS LOW
LEVEL FORCING INCREASES WITH STEEP LOW LEVEL LAPSE RATES. THIS
FRONTAL PASSAGE WILL ALSO LEAD TO AN UPTAKE IN THE WIND SPEEDS OUT
OF THE WEST NORTHWEST BY EARLY FRIDAY EVENING.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN SNOW WITH MVFR VIS AND CIGS.
* MEDIUM CONFIDENCE IN IFR OR LOWER VIS FOR A SHORT PERIOD EARLY
  FRIDAY MORNING.
* LOW CONFIDENCE ON SNOW SHOWERS FRIDAY AFTERNOON.
* MEDIUM CONFIDENCE IN GUSTY WINDS FRIDAY LATE AFTERNOON/EVENING.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR
FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS
LIKELY.

MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH
FREEZING RAIN EARLY. MVFR/IFR CONDITIONS LIKELY.

TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE.

WEDNESDAY...CHANCE LIGHT SNOW SHOWERS. MVFR CONDITIONS POSSIBLE.

RODRIGUEZ

&&

.MARINE...
439 AM CST

AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST
AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT
PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS
ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO
35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH
EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL
HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE
LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN
SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE
EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO
PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH
TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS.
EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY
BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30
KT WINDS EXPECTED TO PERSIST INTO SATURDAY.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 4 PM THURSDAY.

&&

$$







AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 1212 PM CST THU JAN 24 2013

.MESOSCALE DISCUSSION...
955 AM CST

THE LAKE EFFECT SNOW ADVISORY FOR LAKE COUNTY INDIANA WILL LIKELY
BE CANCELLED SHORTLY AS THE LAKE EFFECT SNOW BAND SHIFTS
WESTWARD. MINOR ACCUMULATIONS IN EASTERN COOK COUNTY...ESPECIALLY
SOUTHEAST...ARE STILL ON TRACK.

VISIBLE SATELLITE AND RADAR MOSAIC TOGETHER SHOW AN IMPRESSIVELY
LENGTHY SNOW SHOWER BAND FROM NNE TO SSW ACROSS LAKE MI. WITHIN
THIS HAVE BEEN SOME EMBEDDED CIRCULATIONS AS SEEN ON RADAR...AND
THESE HAVE BEEN NEAR OR MOVED ONSHORE AND LIKELY BEEN RESPONSIBLE
FOR SOME OF THE VERY HEAVY SNOWFALL BURSTS SEEN ON WEBCAMS AND
RELAYED TO THE NWS. THE OVERALL CONVERGENCE CONTINUES TO BE STRONG
MID-LAKE PER STREAMLINE ANALYSIS AND JUST THE LOOK OF THE CLOUDS
ON VISBILE. TOWARD THE NE IL SHORE THIS HAS APPEARED TO WEAKEN
SOME...ALTHOUGH THERE ARE STILL SIGNS OF SMALL SCALE CIRCULATIONS
IN THE REFLECTIVITY. THE 12Z 850MB AND 925MB TEMPERATURES ARE
BOTH AROUND -20C PER MORNING RAOBS AIDING IN SHARP LAPSE RATES OF
AIR FROM THE LAKE. A MODIFIED 14Z MDW AMDAR SOUNDING FOR ESTIMATED
LAKE TEMPERATURES AND MODIFIED DEW POINTS INDICATING NEARLY 500
J/KG OF LAKE INDUCED CAPE. RAP GUIDANCE SHIFTS AND WEAKENS THE
FOCUS OF THE BOUNDARY LAYER CONVERGENCE NORTHWEST DICTATED BY THE
AMBIENT FLOW TURNING MORE ESE THIS AFTERNOON. SO THINKING THAT
WHILE SNOW SHOWERS MAY NOT BE AS CONCENTRATED INTO COOK AND LAKE
COUNTIES IL AS THEY WERE IN NORTHWEST IN EARLIER...THE INSTABILITY
WILL HELP TO DRIVE STRONGER SHOWERS AT TIMES. ONE TO TWO INCH
AMOUNTS ARE LIKELY IN ANY OF THE LAKESHORE AREAS THAT GET UNDER
ONE OF THESE BURSTS EVEN IF FOR JUST A HALF HOUR.

MTF

&&

.DISCUSSION...
358 AM CST

A LOT GOING ON THROUGH THE NEXT 7 DAYS...

TODAY...

LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z.

HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR
NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO
A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS
THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE
BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF
PRODUCING SOME ACCUMULATING SNOW.

HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE
SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE
NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY
SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC
FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER
THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN
FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE
BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST
COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC
PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW
LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR
LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST
RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH
AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS
IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH
PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST
SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL
WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF
PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW
LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED.

TONIGHT THROUGH FRIDAY...

HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO
FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST.

GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE
TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST
ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON.
WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL
ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY
STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY
FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS
DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT
THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH
TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT
900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD
OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL
RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY
FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH
LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY
LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID
RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH
WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS
THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY
BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER
LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW
BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800
MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C
RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED
FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH
AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND
APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS
BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY
NIGHT.

SUNDAY THROUGH WEDNESDAY...

HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE
SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE
RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO
TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55
RFD.

MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE
PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST
OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER
RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE
TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING
FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS
DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN
FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY
DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT
ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT
SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT
INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB
LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL
DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB
THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH
850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS
OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE
PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY
AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT
PERIOD OF SLEET/FREEZING RAIN.

00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER
BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER
SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN.
THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN
DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID-
LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS
OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL
TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY...
THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF
THROUGH THE DAY.

FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS
BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT
EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH
EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT
WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY.
WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS
ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH
PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING
AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE
CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF
THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S
DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT
WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A
MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE
LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT
ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE
THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING
500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY
AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD
SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* SNOW DEVELOPING LATE TONIGHT AND CONTINUING INTO FRIDAY
  MORNING...IFR OR LOWER VIS AND LOW MVFR CIGS POSSIBLE.

* GUSTY WEST-NORTHWEST WINDS LATE FRIDAY AFTERNOON/EVENING.

KJB

//DISCUSSION...UPDATED 18Z...

THE REMNANT LAKE EFFECT SNOW SHOWERS ARE CURRENTLY MOVING ACROSS
ORD...BUT THE LINE HAS WEAKENED CONSIDERABLY...AND IS NOT RESULTING
IN ANY SIGNIFICANT RESTRICTIONS TO THE VISIBILITIES. THIS ACTIVITY
WILL QUICKLY MOVE OUT OF THE AREA BY 1 PM THIS AFTERNOON.

THE WINDS WILL GRADUALLY BECOME EASTERLY AND THEN SOUTHEASTERLY
THROUGH THE AFTERNOON AS HIGH PRESSURE DROPS SOUTHEASTWARD ACROSS
LOWER MICHIGAN.

OUR NEXT STORM SYSTEM WILL MOVE ACROSS THE REGION LATE TONIGHT AND
INTO FRIDAY MORNING. SNOW IS EXPECTED TO DEVELOP AFTER 1 AM NEAR
KRFD AND AFTER 3 AM AT THE EASTERN TERMINALS. THERE WILL BE SOME DRY
AIR TO OVERCOME INITIALLY. HOWEVER...WITH THE DECENT ISENTROPIC
ASCENT AND THE INCREASINGLY SOUTHERLY FLOW...I FEEL THAT THIS DRY
AIR WILL BE OVERCOME FAIRLY QUICKLY. MODEL BUFFER SOUNDINGS INDICATE
SOME DECENT MID LEVEL LAPSE RATES EARLY FRIDAY MORNING...DURING THE
HEIGHT OF THE EVENT. THIS COULD LEAD TO A PERIOD OF SNOW WITH
VISIBILITIES POSSIBLY DROPPING DOWN AROUND 1 MILE FOR A FEW HOURS
TOMORROW MORNING. THE SNOW SHOULD ABATE LATER IN THE MORNING AS THE
MID LEVEL WAVE MOVES EAST OF THE AREA AND DRIER AIR BUILDS INTO THE
MID LEVELS.

A SURFACE LOW WILL BE MOVING ACROSS THE UPPER GREAT LAKES REGION
WITH THE WARM SECTOR BRIEFLY MOVING ACROSS THE AREA FRIDAY EARLY
AFTERNOON BEFORE ANOTHER COLD FRONT COMES PUSHING ACROSS THE AREA BY
VERY LATE AFTERNOON OR EARLY FRIDAY EVENING. IT IS POSSIBLE THAT
SOME ADDITIONAL SNOW SHOWERS COULD DEVELOP DURING THIS TIME AS LOW
LEVEL FORCING INCREASES WITH STEEP LOW LEVEL LAPSE RATES. THIS
FRONTAL PASSAGE WILL ALSO LEAD TO AN UPTAKE IN THE WIND SPEEDS OUT
OF THE WEST NORTHWEST BY EARLY FRIDAY EVENING.

KJB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH CONFIDENCE IN SNOW WITH MVFR VIS AND CIGS.
* MEDIUM CONFIDENCE IN IFR OR LOWER VIS FOR A SHORT PERIOD EARLY
  FRIDAY MORNING.
* LOW CONFIDENCE ON SNOW SHOWERS FRIDAY AFTERNOON.
* MEDIUM CONFIDENCE IN GUSTY WINDS FRIDAY LATE AFTERNOON/EVENING.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR
FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS
LIKELY.

MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH
FREEZING RAIN EARLY. MVFR/IFR CONDITIONS LIKELY.

TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE.

WEDNESDAY...CHANCE LIGHT SNOW SHOWERS. MVFR CONDITIONS POSSIBLE.

RODRIGUEZ

&&

.MARINE...
439 AM CST

AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST
AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT
PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS
ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO
35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH
EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL
HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE
LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN
SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE
EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO
PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH
TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS.
EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY
BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30
KT WINDS EXPECTED TO PERSIST INTO SATURDAY.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 4 PM THURSDAY.

&&

$$







AREA FORECAST DISCUSSION...UPDATED

NWS CHICAGO/ROMEOVILLE IL

 1003 AM CST THU JAN 24 2013

.MESOSCALE DISCUSSION...
955 AM CST

THE LAKE EFFECT SNOW ADVISORY FOR LAKE COUNTY INDIANA WILL LIKELY
BE CANCELLED SHORTLY AS THE LAKE EFFECT SNOW BAND SHIFTS
WESTWARD. MINOR ACCUMULATIONS IN EASTERN COOK COUNTY...ESPECIALLY
SOUTHEAST...ARE STILL ON TRACK.

VISIBLE SATELLITE AND RADAR MOSAIC TOGETHER SHOW AN IMPRESSIVELY
LENGTHY SNOW SHOWER BAND FROM NNE TO SSW ACROSS LAKE MI. WITHIN
THIS HAVE BEEN SOME EMBEDDED CIRCULATIONS AS SEEN ON RADAR...AND
THESE HAVE BEEN NEAR OR MOVED ONSHORE AND LIKELY BEEN RESPONSIBLE
FOR SOME OF THE VERY HEAVY SNOWFALL BURSTS SEEN ON WEBCAMS AND
RELAYED TO THE NWS. THE OVERALL CONVERGENCE CONTINUES TO BE STRONG
MID-LAKE PER STREAMLINE ANALYSIS AND JUST THE LOOK OF THE CLOUDS
ON VISBILE. TOWARD THE NE IL SHORE THIS HAS APPEARED TO WEAKEN
SOME...ALTHOUGH THERE ARE STILL SIGNS OF SMALL SCALE CIRCULATIONS
IN THE REFLECTIVITY. THE 12Z 850MB AND 925MB TEMPERATURES ARE
BOTH AROUND -20C PER MORNING RAOBS AIDING IN SHARP LAPSE RATES OF
AIR FROM THE LAKE. A MODIFIED 14Z MDW AMDAR SOUNDING FOR ESTIMATED
LAKE TEMPERATURES AND MODIFIED DEW POINTS INDICATING NEARLY 500
J/KG OF LAKE INDUCED CAPE. RAP GUIDANCE SHIFTS AND WEAKENS THE
FOCUS OF THE BOUNDARY LAYER CONVERGENCE NORTHWEST DICTATED BY THE
AMBIENT FLOW TURNING MORE ESE THIS AFTERNOON. SO THINKING THAT
WHILE SNOW SHOWERS MAY NOT BE AS CONCENTRATED INTO COOK AND LAKE
COUNTIES IL AS THEY WERE IN NORTHWEST IN EARLIER...THE INSTABILITY
WILL HELP TO DRIVE STRONGER SHOWERS AT TIMES. ONE TO TWO INCH
AMOUNTS ARE LIKELY IN ANY OF THE LAKESHORE AREAS THAT GET UNDER
ONE OF THESE BURSTS EVEN IF FOR JUST A HALF HOUR.

MTF

&&

.DISCUSSION...
358 AM CST

A LOT GOING ON THROUGH THE NEXT 7 DAYS...

TODAY...

LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z.

HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR
NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO
A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS
THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE
BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF
PRODUCING SOME ACCUMULATING SNOW.

HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE
SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE
NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY
SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC
FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER
THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN
FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE
BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST
COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC
PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW
LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR
LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST
RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH
AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS
IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH
PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST
SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL
WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF
PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW
LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED.

TONIGHT THROUGH FRIDAY...

HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO
FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST.

GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE
TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST
ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON.
WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL
ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY
STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY
FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS
DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT
THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH
TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT
900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD
OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL
RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY
FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH
LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY
LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID
RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH
WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS
THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY
BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER
LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW
BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800
MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C
RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED
FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH
AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND
APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS
BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY
NIGHT.

SUNDAY THROUGH WEDNESDAY...

HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE
SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE
RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO
TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55
RFD.

MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE
PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST
OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER
RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE
TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING
FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS
DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN
FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY
DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT
ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT
SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT
INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB
LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL
DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB
THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH
850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS
OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE
PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY
AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT
PERIOD OF SLEET/FREEZING RAIN.

00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER
BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER
SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN.
THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN
DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID-
LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS
OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL
TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY...
THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF
THROUGH THE DAY.

FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS
BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT
EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH
EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT
WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY.
WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS
ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH
PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING
AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE
CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF
THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S
DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT
WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A
MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE
LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT
ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE
THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING
500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY
AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD
SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* LAKE EFFECT SNOW SHOWERS THROUGH EARLY AFTERNOON...POSSIBLY
  DROPPING THE VIS UNDER 3 MILES AND DROPPING CIGS UNDER 2000 FT
  AT MDW AFTER 1645 UTC.

* LIGHT SNOW EXPECTED ONCE AGAIN LATE TONIGHT AND EARLY FRIDAY
  MORNING WITH CEILINGS AND VIS FALLING TO MVFR.

RODRIGUEZ/KB

//DISCUSSION...UPDATED 16Z...
A VERY IMPRESSIVE BAND OF LAKE EFFECT SNOW CONTINUES TO SLOWLY
PROGRESS WEST SOUTHWESTWARD TOWARDS CHICAGO. THE MOST INTENSE BAND
IS BASICALLY OFFSHORE FROM DOWNTOWN SOUTHWARD TO JUST WEST OF
GARY. THE ACTIVITY WITHIN THIS BAND HAS BEEN VERY HEAVY WITH 1/4
OR LESS VIS. THIS BAND SHOULD BEGIN TO WEAKEN OVER THE NEXT HOUR
OR TWO AS THE BOUNDARY LAYER FLOW BEGINS TO SHIFT MORE EAST
SOUTHEASTWARD. HOWEVER...ENOUGH OF A CONVERGENCE ZONE LOOKS TO
REMAIN IN PLACE TO CONTINUE TO SUPPORT LAKE EFFECT SNOW SHOWERS
ACROSS THE AREA INTO THE EARLY TO MID AFTERNOON...BEFORE THE
ACTIVITY RAPIDLY SHIFTS NORTHWARD. CURRENT TIMING WOULD BRING THE
SNOW SHOWERS INTO MDW BY OR JUST PRIOR TO 17 UTC...WITH CONDITIONS
LIKELY DROPPING BELOW 5 MILES ON -SNSH. I WILL CONTINUE TO MONITOR
OVER THE NEXT 30 MINUTES TO SEE IF LOWER VIS IS JUSTIFIED AT MDW.

CONDITIONS REMAIN MORE UNCERTAIN AT ORD AS THE SNOW SHOWERS MAY
STRUGGLE TO GET TO FAR INLAND. HOWEVER...I STILL DO THINK THERE IS
A DECENT POSSIBILITY THAT ORD WILL SEE SOME -SHSN AFTER 1730 UTC.

//DISCUSSION...UPDATED 12Z...

QUIET CONDITIONS TO START OFF THE FORECAST PERIOD HERE WITH ONLY
HIGH LEVEL CIRRUS OVERHEAD. OF MAIN CONCERN THIS MORNING IS
ONGOING LAKE EFFECT SNOW SHOWERS ACROSS NORTHWEST INDIANA...AS
THIS SNOW IS EXPECTED TO DRIFT WESTWARD WITH TIME. AS THIS SNOW
BAND SHIFTS WEST THIS MORNING IT WILL INITIALLY AFFECT GYY WITH
MVFR CEILNGS OF AROUND 2500FT POSSIBLE...AS WELL AS A BRIEF PERIOD
OF LIGHT SNOW BRINGING VIS OF 2-3SM. EXPECT THIS BAND TO REMAIN
TRANSIENT QUICKLY MOVING WEST. THIS SNOW IS THEN EXPECTED TO MOVE
ACROSS NORTHEAST ILLINOIS AFFECTING MDW/ORD BY MID MORNING.
ALTHOUGH LIGHT SNOW IS POSSIBLE...IT DOES APPEAR THAT THE HEAVIER
SNOW SHOWERS SHOULD STAY JUST TO THE EAST OF THE TERMINALS.
NONETHELESS...IT COULD BRING A PERIOD OF MVFR CEILINGS AROUND
2500FT AND VIS TO REMAIN AT AROUND 3-5SM. ONCE AGAIN...THIS MOVING
SNOW SHOULD CONTINUE TO PUSH NORTH INTO THE EARLY AFTERNOON WITH
SNOW ENDING AS WELL AS OVERALL CONDITIONS IMPROVING. EXPECT ONLY
MID LEVEL VFR CEILNGS LATE THIS AFTERNOON AND MOST OF THIS EVENING
AS THE NEXT SYSTEM APPROACHES. CEILINGS WILL FALL ONCE AGAIN LATE
TONIGHT INTO EARLY FRIDAY MORNING AS LIGHT SNOW/LOWER VIS
OVERSPREADS THE TERMINALS AND CONTINUES THROUGH THE REMAINDER OF
THE FORECAST PERIOD.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM TO HIGH CONFIDENCE WITH LIGHT SNOW/MVFR VIS/MVFR CEILINGS
  AT MDW LATER THIS MORNING. LOWER CONFIDENCE AT ORD.

* MEDIUM CONFIDENCE WITH LIGHT SNOW AGAIN LATE TONIGHT AND EARLY
  FRIDAY MORNING.

RODRIGUEZ/KB

//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR
FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS
LIKELY.

MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH
FREEZING RAIN EARLY. MVFR/IFR CONDITIONS LIKELY.

TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE.

WEDNESDAY...CHANCE LIGHT SNOW SHOWERS. MVFR CONDITIONS POSSIBLE.

RODRIGUEZ

&&

.MARINE...
439 AM CST

AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST
AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT
PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS
ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO
35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH
EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL
HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE
LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN
SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE
EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO
PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH
TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS.
EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY
BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30
KT WINDS EXPECTED TO PERSIST INTO SATURDAY.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW ADVISORY...INZ001 UNTIL NOON THURSDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 4 PM THURSDAY.

&&

$$





AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 936 AM CST THU JAN 24 2013

.DISCUSSION...
358 AM CST

A LOT GOING ON THROUGH THE NEXT 7 DAYS...

TODAY...

LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z.

HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR
NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO
A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS
THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE
BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF
PRODUCING SOME ACCUMULATING SNOW.

HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE
SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE
NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY
SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC
FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER
THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN
FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE
BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST
COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC
PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW
LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR
LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST
RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH
AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS
IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH
PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST
SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL
WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF
PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW
LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED.

TONIGHT THROUGH FRIDAY...

HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO
FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST.

GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE
TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST
ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON.
WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL
ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY
STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY
FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS
DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT
THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH
TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT
900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD
OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL
RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY
FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH
LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY
LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID
RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH
WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS
THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY
BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER
LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW
BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800
MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C
RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED
FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH
AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND
APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS
BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY
NIGHT.

SUNDAY THROUGH WEDNESDAY...

HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE
SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE
RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO
TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55
RFD.

MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE
PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST
OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER
RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE
TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING
FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS
DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN
FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY
DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT
ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT
SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT
INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB
LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL
DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB
THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH
850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS
OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE
PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY
AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT
PERIOD OF SLEET/FREEZING RAIN.

00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER
BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER
SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN.
THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN
DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID-
LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS
OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL
TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY...
THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF
THROUGH THE DAY.

FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS
BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT
EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH
EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT
WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY.
WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS
ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH
PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING
AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE
CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF
THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S
DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT
WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A
MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE
LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT
ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE
THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING
500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY
AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD
SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* LAKE EFFECT SNOW SHOWERS THROUGH EARLY AFTERNOON...POSSIBLY
  DROPPING THE VIS UNDER 3 MILES AND DROPPING CIGS UNDER 2000 FT
  AT MDW AFTER 1645 UTC.

* LIGHT SNOW EXPECTED ONCE AGAIN LATE TONIGHT AND EARLY FRIDAY
  MORNING WITH CEILINGS AND VIS FALLING TO MVFR.

RODRIGUEZ/KB

//DISCUSSION...UPDATED 16Z...
A VERY IMPRESSIVE BAND OF LAKE EFFECT SNOW CONTINUES TO SLOWLY
PROGRESS WEST SOUTHWESTWARD TOWARDS CHICAGO. THE MOST INTENSE BAND
IS BASICALLY OFFSHORE FROM DOWNTOWN SOUTHWARD TO JUST WEST OF
GARY. THE ACTIVITY WITHIN THIS BAND HAS BEEN VERY HEAVY WITH 1/4
OR LESS VIS. THIS BAND SHOULD BEGIN TO WEAKEN OVER THE NEXT HOUR
OR TWO AS THE BOUNDARY LAYER FLOW BEGINS TO SHIFT MORE EAST
SOUTHEASTWARD. HOWEVER...ENOUGH OF A CONVERGENCE ZONE LOOKS TO
REMAIN IN PLACE TO CONTINUE TO SUPPORT LAKE EFFECT SNOW SHOWERS
ACROSS THE AREA INTO THE EARLY TO MID AFTERNOON...BEFORE THE
ACTIVITY RAPIDLY SHIFTS NORTHWARD. CURRENT TIMING WOULD BRING THE
SNOW SHOWERS INTO MDW BY OR JUST PRIOR TO 17 UTC...WITH CONDITIONS
LIKELY DROPPING BELOW 5 MILES ON -SNSH. I WILL CONTINUE TO MONITOR
OVER THE NEXT 30 MINUTES TO SEE IF LOWER VIS IS JUSTIFIED AT MDW.

CONDITIONS REMAIN MORE UNCERTAIN AT ORD AS THE SNOW SHOWERS MAY
STRUGGLE TO GET TO FAR INLAND. HOWEVER...I STILL DO THINK THERE IS
A DECENT POSSIBILITY THAT ORD WILL SEE SOME -SHSN AFTER 1730 UTC.



//DISCUSSION...UPDATED 12Z...

QUIET CONDITIONS TO START OFF THE FORECAST PERIOD HERE WITH ONLY
HIGH LEVEL CIRRUS OVERHEAD. OF MAIN CONCERN THIS MORNING IS
ONGOING LAKE EFFECT SNOW SHOWERS ACROSS NORTHWEST INDIANA...AS
THIS SNOW IS EXPECTED TO DRIFT WESTWARD WITH TIME. AS THIS SNOW
BAND SHIFTS WEST THIS MORNING IT WILL INITIALLY AFFECT GYY WITH
MVFR CEILNGS OF AROUND 2500FT POSSIBLE...AS WELL AS A BRIEF PERIOD
OF LIGHT SNOW BRINGING VIS OF 2-3SM. EXPECT THIS BAND TO REMAIN
TRANSIENT QUICKLY MOVING WEST. THIS SNOW IS THEN EXPECTED TO MOVE
ACROSS NORTHEAST ILLINOIS AFFECTING MDW/ORD BY MID MORNING.
ALTHOUGH LIGHT SNOW IS POSSIBLE...IT DOES APPEAR THAT THE HEAVIER
SNOW SHOWERS SHOULD STAY JUST TO THE EAST OF THE TERMINALS.
NONETHELESS...IT COULD BRING A PERIOD OF MVFR CEILINGS AROUND
2500FT AND VIS TO REMAIN AT AROUND 3-5SM. ONCE AGAIN...THIS MOVING
SNOW SHOULD CONTINUE TO PUSH NORTH INTO THE EARLY AFTERNOON WITH
SNOW ENDING AS WELL AS OVERALL CONDITIONS IMPROVING. EXPECT ONLY
MID LEVEL VFR CEILNGS LATE THIS AFTERNOON AND MOST OF THIS EVENING
AS THE NEXT SYSTEM APPROACHES. CEILINGS WILL FALL ONCE AGAIN LATE
TONIGHT INTO EARLY FRIDAY MORNING AS LIGHT SNOW/LOWER VIS
OVERSPREADS THE TERMINALS AND CONTINUES THROUGH THE REMAINDER OF
THE FORECAST PERIOD.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM TO HIGH CONFIDENCE WITH LIGHT SNOW/MVFR VIS/MVFR CEILINGS
  AT MDW LATER THIS MORNING. LOWER CONFIDENCE AT ORD.

* MEDIUM CONFIDENCE WITH LIGHT SNOW AGAIN LATE TONIGHT AND EARLY
  FRIDAY MORNING.

RODRIGUEZ/KB

//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR
FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS
LIKELY.

MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH
FREEZING RAIN EARLY. MVFR/IFR CONDITIONS LIKELY.

TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE.

WEDNESDAY...CHANCE LIGHT SNOW SHOWERS. MVFR CONDITIONS POSSIBLE.

RODRIGUEZ

&&

.MARINE...
439 AM CST

AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST
AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT
PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS
ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO
35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH
EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL
HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE
LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN
SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE
EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO
PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH
TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS.
EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY
BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30
KT WINDS EXPECTED TO PERSIST INTO SATURDAY.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW ADVISORY...INZ001 UNTIL NOON THURSDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 4 PM THURSDAY.

&&

$$





AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 603 AM CST THU JAN 24 2013

.DISCUSSION...
358 AM CST

A LOT GOING ON THROUGH THE NEXT 7 DAYS...

TODAY...

LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z.

HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR
NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO
A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS
THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE
BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF
PRODUCING SOME ACCUMULATING SNOW.

HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE
SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE
NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY
SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC
FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER
THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN
FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE
BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST
COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC
PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW
LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR
LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST
RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH
AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS
IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH
PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST
SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL
WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF
PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW
LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED.

TONIGHT THROUGH FRIDAY...

HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO
FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST.

GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE
TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST
ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON.
WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL
ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY
STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY
FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS
DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT
THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH
TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT
900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD
OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL
RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY
FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH
LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY
LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID
RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH
WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS
THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY
BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER
LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW
BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800
MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C
RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED
FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH
AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND
APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS
BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY
NIGHT.

SUNDAY THROUGH WEDNESDAY...

HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE
SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE
RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO
TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55
RFD.

MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE
PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST
OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER
RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE
TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING
FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS
DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN
FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY
DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT
ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT
SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT
INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB
LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL
DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB
THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH
850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS
OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE
PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY
AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT
PERIOD OF SLEET/FREEZING RAIN.

00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER
BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER
SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN.
THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN
DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID-
LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS
OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL
TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY...
THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF
THROUGH THE DAY.

FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS
BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT
EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH
EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT
WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY.
WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS
ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH
PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING
AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE
CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF
THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S
DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT
WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A
MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE
LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT
ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE
THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING
500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY
AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD
SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* NORTHWEST WINDS WITH SPORADIC GUSTS TO THE MID TEENS THIS
  MORNING...THEN VEERING TO THE NORTHEAST AND THEN SOUTHEAST
  TODAY.

* POSSIBILITY FOR LIGHT SNOW/MVFR VIS/MVFR CEILINGS BY MID MORNING
  TODAY...AND PERSISTING INTO THE EARLY AFTERNOON.

* LIGHT SNOW EXPECTED ONCE AGAIN LATE TONIGHT AND EARLY FRIDAY
  MORNING WITH CEILINGS AND VIS FALLING TO MVFR.

RODRIGUEZ

//DISCUSSION...UPDATED 12Z...

QUIET CONDITIONS TO START OFF THE FORECAST PERIOD HERE WITH ONLY
HIGH LEVEL CIRRUS OVERHEAD. OF MAIN CONCERN THIS MORNING IS
ONGOING LAKE EFFECT SNOW SHOWERS ACROSS NORTHWEST INDIANA...AS
THIS SNOW IS EXPECTED TO DRIFT WESTWARD WITH TIME. AS THIS SNOW
BAND SHIFTS WEST THIS MORNING IT WILL INITIALLY AFFECT GYY WITH
MVFR CEILNGS OF AROUND 2500FT POSSIBLE...AS WELL AS A BRIEF PERIOD
OF LIGHT SNOW BRINGING VIS OF 2-3SM. EXPECT THIS BAND TO REMAIN
TRANSIENT QUICKLY MOVING WEST. THIS SNOW IS THEN EXPECTED TO MOVE
ACROSS NORTHEAST ILLINOIS AFFECTING MDW/ORD BY MID MORNING.
ALTHOUGH LIGHT SNOW IS POSSIBLE...IT DOES APPEAR THAT THE HEAVIER
SNOW SHOWERS SHOULD STAY JUST TO THE EAST OF THE TERMINALS.
NONETHELESS...IT COULD BRING A PERIOD OF MVFR CEILINGS AROUND
2500FT AND VIS TO REMAIN AT AROUND 3-5SM. ONCE AGAIN...THIS MOVING
SNOW SHOULD CONTINUE TO PUSH NORTH INTO THE EARLY AFTERNOON WITH
SNOW ENDING AS WELL AS OVERALL CONDITIONS IMPROVING. EXPECT ONLY
MID LEVEL VFR CEILNGS LATE THIS AFTERNOON AND MOST OF THIS EVENING
AS THE NEXT SYSTEM APPROACHES. CEILINGS WILL FALL ONCE AGAIN LATE
TONIGHT INTO EARLY FRIDAY MORNING AS LIGHT SNOW/LOWER VIS
OVERSPREADS THE TERMINALS AND CONTINUES THROUGH THE REMAINDER OF
THE FORECAST PERIOD.

RODRIGUEZ


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION TODAY.

* MEDIUM CONFIDENCE WITH LIGHT SNOW/MVFR VIS/MVFR CEILINGS TRENDS
  BY MID MORNING.

* MEDIUM CONFIDENCE WITH LIGHT SNOW AGAIN LATE TONIGHT AND EARLY
  FRIDAY MORNING.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...

FRIDAY NIGHT...VFR.

SATURDAY...VFR.

SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR
FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS
LIKELY.

MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH
FREEZING RAIN EARLY. MVFR/IFR CONDITIONS LIKELY.

TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE.

WEDNESDAY...CHANCE LIGHT SNOW SHOWERS. MVFR CONDITIONS POSSIBLE.

RODRIGUEZ

&&

.MARINE...
439 AM CST

AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST
AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT
PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS
ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO
35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH
EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL
HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE
LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN
SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE
EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO
PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH
TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS.
EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY
BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30
KT WINDS EXPECTED TO PERSIST INTO SATURDAY.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW ADVISORY...INZ001-INZ002 UNTIL NOON THURSDAY.

LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-
     LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 AM THURSDAY.

     SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM
     THURSDAY.

     GALE WARNING...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 10 AM THURSDAY.

     SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM THURSDAY TO 4 PM
     THURSDAY.

&&

$$





AREA FORECAST DISCUSSION...CORRECTED

NWS CHICAGO/ROMEOVILLE IL

 522 AM CST THU JAN 24 2013

.DISCUSSION...
358 AM CST

A LOT GOING ON THROUGH THE NEXT 7 DAYS...

TODAY...

LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z.

HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR
NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO
A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS
THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE
BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF
PRODUCING SOME ACCUMULATING SNOW.

HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE
SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE
NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY
SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC
FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER
THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN
FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE
BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST
COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC
PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW
LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR
LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST
RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH
AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS
IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH
PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST
SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL
WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF
PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW
LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED.

TONIGHT THROUGH FRIDAY...

HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO
FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST.

GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE
TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST
ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON.
WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL
ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY
STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY
FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS
DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT
THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH
TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT
900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD
OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL
RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY
FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH
LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY
LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID
RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH
WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS
THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY
BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER
LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW
BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800
MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C
RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED
FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH
AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND
APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS
BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY
NIGHT.

SUNDAY THROUGH WEDNESDAY...

HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE
SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE
RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO
TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55
RFD.

MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE
PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST
OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER
RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE
TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING
FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS
DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN
FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY
DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT
ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT
SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT
INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB
LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL
DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB
THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH
850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS
OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE
PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY
AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT
PERIOD OF SLEET/FREEZING RAIN.

00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER
BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER
SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN.
THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN
DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID-
LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS
OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL
TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY...
THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF
THROUGH THE DAY.

FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS
BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT
EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH
EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT
WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY.
WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS
ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH
PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING
AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE
CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF
THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S
DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT
WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A
MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE
LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT
ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE
THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING
500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY
AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD
SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* NORTHWEST WINDS GUSTING TO THE MID TEENS EARLY THIS
  MORNING...THEN VEERING TO THE NORTHEAST AND THEN SOUTHEAST
  TODAY.

* POSSIBILITY FOR LIGHT SNOW/MVFR VIS/MVFR CEILINGS BY MID MORNING
  TODAY...AND PERSISTING INTO THE EARLY AFTERNOON.

* POSSIBILITY FOR LIGHT SNOW AGAIN LATE IN THE PERIOD...EARLY
  FRIDAY MORNING.

RODRIGUEZ

//DISCUSSION...UPDATED 06Z...

MAIN CONCERNS TODAY WILL BE CENTERED AROUND ONGOING LAKE EFFECT
SNOW SHOWERS CURRENTLY PUSHING SOUTH THROUGH NORTHWEST INDIANA.
EXPECT THESE SNOW SHOWERS TO PERSIST THIS MORNING INITIALLY
AFFECTING GYY IN THE NEAR TERM...WITH VIS DROPPING BELOW 1 MILE AT
TIMES. THIS SHOULD AFFECT GYY THROUGH AROUND THE 12Z TIME...WITH
THIS SNOW THEN SHIFTING MORE TOWARDS NORTHEAST ILLINOIS. ALTHOUGH
THIS SNOW WILL MOVE TOWARDS THE MDW/ORD TERMINALS...EXPECT A
SLIGHT DIMINISHING TREND BUT OF MORE IMPORTANCE EXPECT THE MAIN
SNOW BAND TO REMAIN JUST EAST OF THE TERMINALS. DESPITE THIS...DO
EXPECT VIS OF 3-5SM IN LIGHT SNOW TO BE POSSIBLE FOR ORD/MDW
THROUGH MID TO LATE MORNING BEFORE IT CONTINUES TO SHIFT NORTHEAST
OUT OF THE AREA.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION.

* MEDIUM CONFIDENCE WITH LIGHT SNOW/MVFR VIS/MVFR CEILINGS TRENDS
  BY MID MORNING.

* MEDIUM CONFIDENCE WITH LIGHT SNOW AGAIN LATE IN THE PERIOD.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

FRIDAY...SNOW LIKELY...MAINLY IN THE MORNING...WITH IFR CONDITIONS
AND LIGHT SNOW POSSIBLY LINGERING THROUGH THE AFTERNOON.
CONDITIONS SHOULD IMPROVE TO VFR IN THE EVENING.

SATURDAY...VFR. WX NIL.

SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR
FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS
LIKELY.

MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH FREEZING
RAIN EARLY...AND POSSIBLY MIXING WITH SNOW OVERNIGHT. MVFR/IFR
CONDITIONS LIKELY.

TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE.

KREIN

&&

.MARINE...
439 AM CST

AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST
AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT
PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS
ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO
35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH
EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL
HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE
LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN
SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE
EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO
PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH
TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS.
EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY
BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30
KT WINDS EXPECTED TO PERSIST INTO SATURDAY.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW ADVISORY...INZ001-INZ002 UNTIL NOON THURSDAY.

LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-
     LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 AM THURSDAY.

     SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM
     THURSDAY.

     GALE WARNING...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 10 AM THURSDAY.

     SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM THURSDAY TO 4 PM
     THURSDAY.

&&

$$







AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 439 AM CST THU JAN 24 2013

.DISCUSSION...
358 AM CST

- - DDHHMM
WRKMAR

A LOT GOING ON THROUGH THE NEXT 7 DAYS...

TODAY...

LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z.

HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR
NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO
A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS
THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE
BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF
PRODUCING SOME ACCUMULATING SNOW.

HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE
SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE
NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY
SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC
FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER
THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN
FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE
BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST
COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC
PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW
LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR
LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST
RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH
AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS
IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH
PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST
SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL
WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF
PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW
LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED.

TONIGHT THROUGH FRIDAY...

HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO
FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST.

GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE
TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST
ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON.
WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL
ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY
STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY
FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS
DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT
THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH
TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT
900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD
OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL
RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY
FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH
LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY
LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID
RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH
WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS
THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY
BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER
LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW
BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800
MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C
RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED
FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH
AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND
APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS
BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY
NIGHT.

SUNDAY THROUGH WEDNESDAY...

HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE
SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE
RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO
TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55
RFD.

MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE
PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST
OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER
RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE
TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING
FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS
DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN
FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY
DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT
ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT
SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT
INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB
LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL
DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB
THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH
850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS
OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE
PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY
AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT
PERIOD OF SLEET/FREEZING RAIN.

00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER
BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER
SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN.
THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN
DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID-
LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS
OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL
TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY...
THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF
THROUGH THE DAY.

FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS
BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT
EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH
EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT
WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY.
WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS
ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH
PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING
AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE
CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF
THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S
DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT
WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A
MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE
LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT
ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE
THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING
500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY
AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD
SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* NORTHWEST WINDS GUSTING TO THE MID TEENS EARLY THIS
  MORNING...THEN VEERING TO THE NORTHEAST AND THEN SOUTHEAST
  TODAY.

* POSSIBILITY FOR LIGHT SNOW/MVFR VIS/MVFR CEILINGS BY MID MORNING
  TODAY...AND PERSISTING INTO THE EARLY AFTERNOON.

* POSSIBILITY FOR LIGHT SNOW AGAIN LATE IN THE PERIOD...EARLY
  FRIDAY MORNING.

RODRIGUEZ

//DISCUSSION...UPDATED 06Z...

MAIN CONCERNS TODAY WILL BE CENTERED AROUND ONGOING LAKE EFFECT
SNOW SHOWERS CURRENTLY PUSHING SOUTH THROUGH NORTHWEST INDIANA.
EXPECT THESE SNOW SHOWERS TO PERSIST THIS MORNING INITIALLY
AFFECTING GYY IN THE NEAR TERM...WITH VIS DROPPING BELOW 1 MILE AT
TIMES. THIS SHOULD AFFECT GYY THROUGH AROUND THE 12Z TIME...WITH
THIS SNOW THEN SHIFTING MORE TOWARDS NORTHEAST ILLINOIS. ALTHOUGH
THIS SNOW WILL MOVE TOWARDS THE MDW/ORD TERMINALS...EXPECT A
SLIGHT DIMINISHING TREND BUT OF MORE IMPORTANCE EXPECT THE MAIN
SNOW BAND TO REMAIN JUST EAST OF THE TERMINALS. DESPITE THIS...DO
EXPECT VIS OF 3-5SM IN LIGHT SNOW TO BE POSSIBLE FOR ORD/MDW
THROUGH MID TO LATE MORNING BEFORE IT CONTINUES TO SHIFT NORTHEAST
OUT OF THE AREA.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION.

* MEDIUM CONFIDENCE WITH LIGHT SNOW/MVFR VIS/MVFR CEILINGS TRENDS
  BY MID MORNING.

* MEDIUM CONFIDENCE WITH LIGHT SNOW AGAIN LATE IN THE PERIOD.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

FRIDAY...SNOW LIKELY...MAINLY IN THE MORNING...WITH IFR CONDITIONS
AND LIGHT SNOW POSSIBLY LINGERING THROUGH THE AFTERNOON.
CONDITIONS SHOULD IMPROVE TO VFR IN THE EVENING.

SATURDAY...VFR. WX NIL.

SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR
FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS
LIKELY.

MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH FREEZING
RAIN EARLY...AND POSSIBLY MIXING WITH SNOW OVERNIGHT. MVFR/IFR
CONDITIONS LIKELY.

TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE.

KREIN

&&

.MARINE...
439 AM CST

AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST
AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT
PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS
ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO
35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH
EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL
HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE
LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN
SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE
EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO
PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH
TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS.
EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY
BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30
KT WINDS EXPECTED TO PERSIST INTO SATURDAY.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW ADVISORY...INZ001-INZ002 UNTIL NOON THURSDAY.

LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-
     LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 AM THURSDAY.

     SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM
     THURSDAY.

     GALE WARNING...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 10 AM THURSDAY.

     SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM THURSDAY TO 4 PM
     THURSDAY.

&&

$$





AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 358 AM CST THU JAN 24 2013

.DISCUSSION...
358 AM CST

- - DDHHMM
WRKMAR

A LOT GOING ON THROUGH THE NEXT 7 DAYS...

TODAY...

LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z.

HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR
NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO
A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS
THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE
BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF
PRODUCING SOME ACCUMULATING SNOW.

HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE
SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE
NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY
SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC
FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER
THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN
FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE
BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST
COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC
PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW
LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR
LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST
RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH
AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS
IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH
PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST
SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL
WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF
PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW
LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED.

TONIGHT THROUGH FRIDAY...

HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO
FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST.

GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE
TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST
ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON.
WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL
ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY
STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY
FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS
DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT
THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH
TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT
900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD
OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL
RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY
FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH
LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY
LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID
RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH
WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS
THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY
BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER
LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW
BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800
MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C
RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED
FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH
AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND
APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS
BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY
NIGHT.

SUNDAY THROUGH WEDNESDAY...

HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE
SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE
RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO
TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55
RFD.

MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE
PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST
OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER
RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE
TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING
FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS
DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN
FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY
DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT
ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT
SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT
INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB
LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL
DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB
THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH
850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS
OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE
PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY
AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT
PERIOD OF SLEET/FREEZING RAIN.

00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER
BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER
SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN.
THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN
DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID-
LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS
OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL
TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY...
THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF
THROUGH THE DAY.

FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS
BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT
EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH
EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT
WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY.
WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS
ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH
PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING
AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE
CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF
THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S
DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT
WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A
MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE
LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT
ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE
THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING
500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY
AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD
SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* NORTHWEST WINDS GUSTING TO THE MID TEENS EARLY THIS
  MORNING...THEN VEERING TO THE NORTHEAST AND THEN SOUTHEAST
  TODAY.

* POSSIBILITY FOR LIGHT SNOW/MVFR VIS/MVFR CEILINGS BY MID MORNING
  TODAY...AND PERSISTING INTO THE EARLY AFTERNOON.

* POSSIBILITY FOR LIGHT SNOW AGAIN LATE IN THE PERIOD...EARLY
  FRIDAY MORNING.

RODRIGUEZ

//DISCUSSION...UPDATED 06Z...

MAIN CONCERNS TODAY WILL BE CENTERED AROUND ONGOING LAKE EFFECT
SNOW SHOWERS CURRENTLY PUSHING SOUTH THROUGH NORTHWEST INDIANA.
EXPECT THESE SNOW SHOWERS TO PERSIST THIS MORNING INITIALLY
AFFECTING GYY IN THE NEAR TERM...WITH VIS DROPPING BELOW 1 MILE AT
TIMES. THIS SHOULD AFFECT GYY THROUGH AROUND THE 12Z TIME...WITH
THIS SNOW THEN SHIFTING MORE TOWARDS NORTHEAST ILLINOIS. ALTHOUGH
THIS SNOW WILL MOVE TOWARDS THE MDW/ORD TERMINALS...EXPECT A
SLIGHT DIMINISHING TREND BUT OF MORE IMPORTANCE EXPECT THE MAIN
SNOW BAND TO REMAIN JUST EAST OF THE TERMINALS. DESPITE THIS...DO
EXPECT VIS OF 3-5SM IN LIGHT SNOW TO BE POSSIBLE FOR ORD/MDW
THROUGH MID TO LATE MORNING BEFORE IT CONTINUES TO SHIFT NORTHEAST
OUT OF THE AREA.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION.

* MEDIUM CONFIDENCE WITH LIGHT SNOW/MVFR VIS/MVFR CEILINGS TRENDS
  BY MID MORNING.

* MEDIUM CONFIDENCE WITH LIGHT SNOW AGAIN LATE IN THE PERIOD.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

FRIDAY...SNOW LIKELY...MAINLY IN THE MORNING...WITH IFR CONDITIONS
AND LIGHT SNOW POSSIBLY LINGERING THROUGH THE AFTERNOON.
CONDITIONS SHOULD IMPROVE TO VFR IN THE EVENING.

SATURDAY...VFR. WX NIL.

SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR
FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS
LIKELY.

MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH FREEZING
RAIN EARLY...AND POSSIBLY MIXING WITH SNOW OVERNIGHT. MVFR/IFR
CONDITIONS LIKELY.

TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE.

KREIN

&&

.MARINE...
230 PM CST

A QUICKLY MIGRATING PATTERN OVER LAKE MICHIGAN THROUGH SATURDAY WILL
KEEP WIND SHIFTS AND UPS AND DOWNS IN SPEEDS FREQUENT. A DEVELOPING
COLD FRONT WILL MOVE DOWN THE LAKE THIS EVENING AND BECAUSE OF AN
IMPEDING STRONG HIGH FROM THE NORTHERN PLAINS...THE PRESSURE
GRADIENT RAPIDLY TIGHTENS. WITH CONCURRENT COLD AIR ADVECTION THIS
EVENING...NORTHERLY WINDS WILL INCREASE QUICKLY AFTER THE FRONT
INCLUDING AT LEAST OCCASIONAL GALES. HAVE OPTED TO GO WITH A GALE
WARNING FOR THE SOUTHERN HALF OF THE LAKE FOR THIS...AS THE DURATION
LOOKS TO BE SIX TO NINE HOURS OF SUCH WINDS. WITH THE ONSHORE FLOW
INTO THE INDIANA SHORE HAVE ALSO GONE WITH A GALE WARNING FOR
THERE. THE COMBINATION OF THESE WINDS AND THE FALLING TEMPERATURES
WILL OFFER A MODERATE FREEZING SPRAY THREAT TONIGHT.

THEN A BRIEF PERIOD OF HIGH PRESSURE WILL PREVAIL BEFORE THE NEXT
LOW PRESSURE APPROACHING THURSDAY NIGHT AND MOVING PAST BY LATER
FRIDAY. THIS WILL HAVE MODEST SOUTHERLY FLOW AHEAD OF IT DUE AGAIN
TO THE STRONG PRESSURE GRADIENT SET UP BY THE QUICK MOVING
PATTERN. AFTER ANOTHER HIGH PRESSURE SATURDAY THE PATTERN SHIFTS
SOMEWHAT ALLOWING LOW PRESSURES TO APPROACH THE LAKE FROM THE
SOUTHWEST. A SOMEWHAT WEAK LOW IS PROJECTED ON SUNDAY NIGHT INTO
MONDAY BEFORE A STRONG ONE DURING MIDWEEK. ALL THIS WILL LIKELY
MEAN SOUTHERLY FLOW...ESPECIALLY LATER MONDAY THROUGH TUESDAY.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...LAKE EFFECT SNOW ADVISORY...INZ001-INZ002 UNTIL NOON THURSDAY.

LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM
     THURSDAY.

     GALE WARNING...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM THURSDAY.

     SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 PM THURSDAY.

&&

$$








AREA FORECAST DISCUSSION

NWS INDIANAPOLIS IN

 920 AM EST THU JAN 24 2013

.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW

&&

.SYNOPSIS...
ISSUED AT 338 AM EST THU JAN 24 2013

HIGH PRESSURE WILL BRING DRY CHILLY WEATHER TO CENTRAL INDIANA
TODAY. LOW PRESSURE WILL TRACK THROUGH THE GREAT LAKES ON
FRIDAY...WITH SNOW DEVELOPING LATE TONIGHT AND CONTINUING THROUGH
FRIDAY AFTERNOON. A MORE ACTIVE WEATHER PATTERN ARRIVES BEGINNING
SUNDAY AND CONTINUING INTO NEXT WEEK AS A WARM FRONT LIFTS INTO THE
REGION WITH SEVERAL DISTURBANCES TRACKING ALONG IT. AFTER THE
POTENTIAL FOR A WINTRY MIX SUNDAY AFTERNOON AND NIGHT...TEMPERATURES
WILL BE WARM ENOUGH FOR RAIN FOR MUCH OF NEXT WEEK.

&&

.NEAR TERM /TODAY/...
ISSUED AT 338 AM EST THU JAN 24 2013

LAKE EFFECT SNOW SHOWERS AND FLURRIES CONTINUE TO MOVE SOUTH INTO
THE NORTHERN HALF OF THE FORECAST AREA EARLY THIS MORNING. OUTSIDE
OF SNOW SHOWERS/FLURRIES...SKIES WERE PARTLY CLOUDY AS HIGH PRESSURE
BEGINNING TO EXPAND INTO THE REGION. TEMPS WERE FALLING THROUGH THE
20S AND INTO THE TEENS AS COLD ADVECTION ESTABLISHES.

INITIAL FOCUS OF THE NEAR TERM IS ON THE TRANSIENT NATURE OF THE
SNOW SHOWERS AND FLURRIES COMING OUT OF NORTHERN INDIANA AND INTO
NORTHERN COUNTIES. LOW LEVEL FLOW VIA THE MOST RECENT RAP DATA
REMAINS FROM THE NORTHWEST WITH THE VAD PROFILE OFF OF THE KIND
RADAR INDICATING 25-30KTS PRESENT AT ABOUT 3KFT. HAVE SEEN POCKETS
OF HEAVIER SNOW SHOWERS WITHIN A BAND EXTENDING FROM LOGANSPORT
SOUTHEAST THROUGH KOKOMO TO NEAR NOBLESVILLE. EXPECT THESE SNOW
SHOWERS/FLURRIES TO SHIFT WEST AND WEAKEN AS THEY DROP SOUTH WITH
BOUNDARY LAYER FLOW SET TO VEER TO A MORE NORTHERLY DIRECTION
THROUGH DAYBREAK. THERE ARE SIGNS THIS SHIFT IN LOW LEVEL FLOW IS
ALREADY BEGINNING AS AN INCREASINGLY DOMINANT SNOW BAND DEVELOPING
DUE SOUTH OFF OF LAKE MICHIGAN OVER LAKE AND PORTER COS. POTENTIAL
REMAINS FOR THE OUTER FRINGES OF THIS BAND TO WORK ALL THE WAY SOUTH
INTO CARROLL AND TIPPECANOE COS AFTER 09Z AND THROUGH DAYBREAK
BEFORE LOW LEVEL FLOW VEERS FURTHER AND WEAKENS. HAVE HELD ONTO LOW
CHANCE POPS FOR THE NEXT FEW HOURS TO ACCOUNT FOR ONGOING SNOW
SHOWERS...THEN REFOCUSED IT OVER THE NORTHERN WABASH VALLEY TO
ENCOMPASS ABOVE THOUGHTS. COULD SEE A DUSTING IN LOCALIZED AREAS
OVER THE NEXT FEW HOURS TO THE NORTH OF INDY...BUT WITH A DRY SNOW
MOST WILL BE BLOWN AROUND MORE THAN ANYTHING ELSE.

BROAD CANADIAN HIGH PRESSURE WILL THEN TAKE OVER FOR THE REMAINDER
OF THE SHORT TERM...WITH ANOTHER SURGE OF DRY ARCTIC AIR SPREADING
ACROSS THE REGION. DEEP SUBSIDENCE EXPANDING INTO THE BOUNDARY LAYER
WILL LEAD TO MOSTLY SUNNY SKIES THROUGH MIDDAY...WITH A SLOW
EXPANSION IN MID AND HIGH LEVEL CLOUDS BY LATE AFTERNOON AS MOISTURE
ALOFT SPREADS INTO THE REGION FROM THE NORTHWEST. WIND GUSTS THIS
MORNING SHOULD DROP OFF RATHER QUICKLY AS THE CENTER OF THE HIGH
MOVES ACROSS THE REGION THIS AFTERNOON.

TEMPS...COLD ADVECTION THROUGH THE AFTERNOON WILL KEEP IT CHILLY...
WITH LOW LEVEL THERMALS SUPPORTING MOS TEMPS IN THE LOWER TO MID
20S.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
ISSUED AT 338 AM EST THU JAN 24 2013

FORECAST CHALLENGES FOCUS ON SNOW CHANCES LATE TONIGHT THROUGH
FRIDAY AS LOW PRESSURE DROPS THROUGH THE GREAT LAKES. STILL SOME
DISCREPANCIES BETWEEN MODELS WITH RESPECT TO MOISTURE AVAILABILITY
AND FORCING ASSOCIATED WITH THE SURFACE WAVE...BUT OVERALL GUIDANCE
IN BETTER AGREEMENT THIS MORNING ON THE MAIN FEATURES.

CLOUDS WILL INCREASE TONIGHT AS THE WAVE APPROACHES FROM THE
NORTHWEST AS ISENTROPIC LIFT AND MOISTURE DEVELOP ALONG A BOUNDARY
OVER THE TENNESSEE VALLEY. SUSPECT MOISTENING OF THE LOWER LEVELS
WILL TAKE SOME TIME AND EFFORT AFTER MIDNIGHT AS SURFACE FLOW
DIRECTION VEERS ONLY SLOWLY FROM EASTERLY TO A MORE S/SE DIRECTION
BY 12Z FRIDAY. HAVE DELAYED ONSET OF POPS UNTIL LATE TONIGHT WITH
THE INITIAL VERY DRY BOUNDARY LAYER. STILL HAVE QUESTIONS AS TO THE
DEPTH OF THE MOISTURE THAT WILL ACCOMPANY THE SYSTEM...AS NO STRONG
GULF FEED WILL BE PRESENT WITH BOUNDARY LAYER WINDS SHIFTING MORE TO
A W/SW FLOW.

BRIEF PERIOD OF ISENTROPIC LIFT DEVELOPS JUST PRIOR TO DAYBREAK AND
EXTENDS THROUGH THE MORNING FRIDAY BEFORE MOISTURE AND MORE
SUBSTANTIAL LIFT SHIFTS EAST INTO THE AFTERNOON. MODEL SOUNDINGS
CONTINUE TO SHOW PRECIP FALLING AS ALL SNOW ACROSS THE FORECAST
AREA...ALTHOUGH HINTS OF A THIN LAYER OF ABOVE FREEZING AIR IN THE
BOUNDARY LAYER BRIEFLY COMING INTO SOUTHERN INDIANA FRIDAY MORNING
HAVE RETURNED. FOCUS OF HEAVIEST SNOWFALL FRIDAY MORNING SHOULD SET
UP OVER THE NORTHEAST HALF OF THE FORECAST AREA WHERE AXIS OF
STRONGEST ISENTROPIC LIFT COMBINES WITH A PERIOD WITH GREATER
VERTICAL VELOCITIES AND A SLIGHTLY DEEPER DENDRITIC GROWTH ZONE.
WITH SNOW RATIOS LIKELY TO BE ELEVATED AND CLOSER TO 15 TO 1 IN
THESE AREAS...FEEL COMFORTABLE PLACING A GENERAL 1 TO 2 INCHES
THROUGH FRIDAY AFTERNOON NORTHEAST OF A ROCKVILLE-MARTINSVILLE-
COLUMBUS LINE WITH AMOUNTS DROPPING OFF QUICKLY TO THE SOUTH OF THAT
LINE. OP GFS EVEN HINTS AT DEVELOPMENT OF A TROWAL OVER OHIO FRIDAY
MORNING WHICH MAY SERVE TO ENHANCE LIFT EVEN A TOUCH MORE OVER
NORTHEAST COUNTIES AND ENABLE A FEW SPOTS FROM KOKOMO TO MUNCIE AND
WINCHESTER TO MAKE A RUN AT 2 TO 3 INCHES FOR A FINAL TALLY.

DRIER AIR WILL ADVECT INTO THE REGION FROM THE WEST RATHER QUICKLY
ON FRIDAY AFTERNOON...SHUTTING OFF LIGHT SNOW FOR MOST OF THE REGION
AND POTENTIALLY EVEN LEADING TO SOME CLEARING LATE. HAVE HELD ONTO
LOW CHANCE POPS HOWEVER THROUGH THE REST OF THE AFTERNOON OVER
NORTHEAST HALF OF THE FORECAST AREA AS A SECONDARY WAVE ALOFT DROPS
THROUGH THE LOWER GREAT LAKES WITH THE SURFACE LOW AND MAY SERVE TO
MAINTAIN SCATTERED LIGHT SNOW SHOWERS OR FLURRIES. ANY LINGERING
FLURRIES WILL END OVER NORTHEAST COUNTIES FRIDAY EVENING WITH HIGH
PRESSURE REESTABLISHING OVER THE REGION FOR THE REMAINDER OF THE
SHORT TERM. THE HIGH WILL BRING ANOTHER SHOT OF COLDER AIR FOR
FRIDAY NIGHT AND SATURDAY...BUT WARM ADVECTION WILL COMMENCE
SATURDAY NIGHT AS THE HIGH MOVES OFF TO THE EAST AND RIDGING ALOFT
EXPANDS INTO THE OHIO VALLEY. MID AND HIGH LEVEL CLOUD COVER WILL
INCREASE LATE SATURDAY NIGHT AS LOW PRESSURE AND AN ASSOCIATED WARM
FRONT LIFTS OUT OF THE CENTRAL PLAINS.

TEMPS...PREFERRED COOLER METMOS GUIDANCE FOR HIGHS FRIDAY AS CLOUDS
AND PRECIP FOR MUCH OF THE DAY FOLLOWED BY COLD ADVECTION. MAVMOS
LOOKED REASONABLE FOR HIGHS SATURDAY PRIMARILY IN THE MID AND UPPER
20S. TRENDED TOWARDS MAVMOS FOR LOWS TONIGHT...THEN GENERALLY WENT
AT OR A COUPLE DEGREES BELOW GUIDANCE FOR FRI/SAT NIGHTS CONSIDERING
MAY HAVE A THIN SNOW COVER IN SOME SPOTS.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
ISSUED AT 327 AM EST THU JAN 24 2013

AN ACTIVE WEATHER PATTERN SETS UP IN THE LONG TERM WITH AN UPPER
TROUGH MOVING THROUGH THE PACIFIC NORTHWEST INTO THE CENTRAL U.S.
THROUGH THE PERIOD. A SERIES OF UPPER SHORTWAVES WILL EJECT FROM THE
UPPER TROUGH AND BRING CHANCES FOR PRECIPITATION TO THE AREA. AT THE
SURFACE A WARM FRONT WILL FORM SOUTH OF THE AREA AND SLOWLY MOVE
NORTH BEFORE THE SURFACE LOW EJECTS FROM THE PLAINS AND TRAVERSES
THE GREAT LAKES. MODELS HAVE SOME MINOR DISAGREEMENTS IN
TIMING/TEMPERATURES EARLY WITH SIGNIFICANT DIFFERENCES BY TUESDAY
NIGHT. GENERALLY ACCEPTED ALLBLEND INITIALIZATION. BIGGEST CHALLENGE
WILL BE PRECIPITATION TYPE FOR SUNDAY-MONDAY. ENTIRE COLUMN IS BELOW
FREEZING SUNDAY MORNING BEFORE PRECIPITATION ARRIVES. BY SUNDAY
AFTERNOON WITH UPPER SHORTWAVE APPROACHING ECMWF AND GFS SHOW AN
INTRUSION OF WARM AIR ALOFT INTO THE SOUTHWEST AND BY SUNDAY NIGHT
THIS MOVES ALL ACROSS THE AREA. MOST OF THE AREA SHOULD SEE A
PROGRESSION FROM A CHANCE FOR SNOW TO A CHANCE FOR SNOW AND SLEET TO
A CHANCE FOR FREEZING RAIN AND SLEET BEFORE TRANSITIONING TO RAIN.
TRIED TO MATCH TRANSITION UP WITH FORECAST SOUNDINGS AND PARTIAL
THICKNESSES...BUT BOTTOM LINE IS MUCH OF THE AREA WILL SEE SOME TYPE
OF WINTRY MIX BEFORE THE TRANSITION TO ALL RAIN WHICH SHOULD OCCUR
BY SOMETIME MONDAY MORNING. THEN CHANCES FOR RAIN WILL BE THE RULE
UNTIL WEDNESDAY WHEN PRECIP TYPE IS UP IN THE AIR BECAUSE OF
AFOREMENTIONED SIGNIFICANT MODEL TEMPERATURE DIFFERENCES.

ANOTHER ITEM OF NOTE IS THE STRENGTH OF THE SYSTEM EJECTING FROM THE
PLAINS TUESDAY/TUESDAY NIGHT. IF THE VERY WARM GFS WERE TO VERIFY
COULD SEE CHANCES FOR THUNDER EEK THIS FAR NORTH. WILL LEAVE OUT FOR
NOW AS ECMWF PAINTS A MUCH DIFFERENT PICTURE AND WOULD RATHER HAVE
SOME AGREEMENT TO INCLUDE THUNDER THIS TIME OF YEAR.

&&

.AVIATION /DISCUSSION FOR 241500Z IND TAF UPDATE/...

ISSUED AT 920 AM EST THU JAN 24 2013

OBSERVATIONAL...SATELLITE AND RADAR TRENDS ALONG WITH MODEL TIME
SECTIONS SUGGEST THERE WILL BE LITTLE TO NO CU THE REST OF THE DAY
WITH ONLY THICK CIRRUS LEFT BEHIND. SO...PULLED SCATTERED
CU...OTHERWISE...TAF LOOKS GOOD.

PREVIOUS DISCUSSION FOLLOWS...

MAINLY VFR CONDITIONS AT THE SITES THROUGH THE PERIOD. THE ONLY
EXCEPTION TO THIS COULD BE OVER THE NEXT COUPLE OF HOURS WITH LAKE
EFFECT SNOW SHOWERS CONTINUING TO DRIFT SOUTH. THESE LEFTOVER ECHOES
COULD BRIEFLY DROP KIND AND KBMG TO MVFR BUT DO NOT EXPECT THIS TO
LAST FOR LONG. COULD ACTUALLY BE FINISHED ISSUANCE TIME AT KIND BUT
MAY INCLUDE A BRIEF MENTION AT KBMG FOR MVFR CEILINGS. AFTER THAT
ONLY SOME CIRRUS EXPECTED THROUGH THE DAY. A CLIPPER SYSTEM WILL
APPROACH NEAR THE END OF THE PERIOD AND BRING LOWERING
CEILINGS...BUT DON/T EXPECT AN IMPACT ON FLYING CONDITIONS UNTIL THE
EXTENDED PORTION OF THE TAF.

WINDS WILL SHIFT FROM NORTHWEST TO NORTHEAST LATER THIS MORNING
BEFORE BECOMING SOUTHEASTERLY THIS EVENING. SPEED GENERALLY 5 TO 12
KTS WITH NO GUSTS EXPECTED.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....CP
AVIATION...CP/MK










AREA FORECAST DISCUSSION

NWS INDIANAPOLIS IN

 550 AM EST THU JAN 24 2013

.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW

&&

.SYNOPSIS...
ISSUED AT 338 AM EST THU JAN 24 2013

HIGH PRESSURE WILL BRING DRY CHILLY WEATHER TO CENTRAL INDIANA
TODAY. LOW PRESSURE WILL TRACK THROUGH THE GREAT LAKES ON
FRIDAY...WITH SNOW DEVELOPING LATE TONIGHT AND CONTINUING THROUGH
FRIDAY AFTERNOON. A MORE ACTIVE WEATHER PATTERN ARRIVES BEGINNING
SUNDAY AND CONTINUING INTO NEXT WEEK AS A WARM FRONT LIFTS INTO THE
REGION WITH SEVERAL DISTURBANCES TRACKING ALONG IT. AFTER THE
POTENTIAL FOR A WINTRY MIX SUNDAY AFTERNOON AND NIGHT...TEMPERATURES
WILL BE WARM ENOUGH FOR RAIN FOR MUCH OF NEXT WEEK.

&&

.NEAR TERM /TODAY/...
ISSUED AT 338 AM EST THU JAN 24 2013

LAKE EFFECT SNOW SHOWERS AND FLURRIES CONTINUE TO MOVE SOUTH INTO
THE NORTHERN HALF OF THE FORECAST AREA EARLY THIS MORNING. OUTSIDE
OF SNOW SHOWERS/FLURRIES...SKIES WERE PARTLY CLOUDY AS HIGH PRESSURE
BEGINNING TO EXPAND INTO THE REGION. TEMPS WERE FALLING THROUGH THE
20S AND INTO THE TEENS AS COLD ADVECTION ESTABLISHES.

INITIAL FOCUS OF THE NEAR TERM IS ON THE TRANSIENT NATURE OF THE
SNOW SHOWERS AND FLURRIES COMING OUT OF NORTHERN INDIANA AND INTO
NORTHERN COUNTIES. LOW LEVEL FLOW VIA THE MOST RECENT RAP DATA
REMAINS FROM THE NORTHWEST WITH THE VAD PROFILE OFF OF THE KIND
RADAR INDICATING 25-30KTS PRESENT AT ABOUT 3KFT. HAVE SEEN POCKETS
OF HEAVIER SNOW SHOWERS WITHIN A BAND EXTENDING FROM LOGANSPORT
SOUTHEAST THROUGH KOKOMO TO NEAR NOBLESVILLE. EXPECT THESE SNOW
SHOWERS/FLURRIES TO SHIFT WEST AND WEAKEN AS THEY DROP SOUTH WITH
BOUNDARY LAYER FLOW SET TO VEER TO A MORE NORTHERLY DIRECTION
THROUGH DAYBREAK. THERE ARE SIGNS THIS SHIFT IN LOW LEVEL FLOW IS
ALREADY BEGINNING AS AN INCREASINGLY DOMINANT SNOW BAND DEVELOPING
DUE SOUTH OFF OF LAKE MICHIGAN OVER LAKE AND PORTER COS. POTENTIAL
REMAINS FOR THE OUTER FRINGES OF THIS BAND TO WORK ALL THE WAY SOUTH
INTO CARROLL AND TIPPECANOE COS AFTER 09Z AND THROUGH DAYBREAK
BEFORE LOW LEVEL FLOW VEERS FURTHER AND WEAKENS. HAVE HELD ONTO LOW
CHANCE POPS FOR THE NEXT FEW HOURS TO ACCOUNT FOR ONGOING SNOW
SHOWERS...THEN REFOCUSED IT OVER THE NORTHERN WABASH VALLEY TO
ENCOMPASS ABOVE THOUGHTS. COULD SEE A DUSTING IN LOCALIZED AREAS
OVER THE NEXT FEW HOURS TO THE NORTH OF INDY...BUT WITH A DRY SNOW
MOST WILL BE BLOWN AROUND MORE THAN ANYTHING ELSE.

BROAD CANADIAN HIGH PRESSURE WILL THEN TAKE OVER FOR THE REMAINDER
OF THE SHORT TERM...WITH ANOTHER SURGE OF DRY ARCTIC AIR SPREADING
ACROSS THE REGION. DEEP SUBSIDENCE EXPANDING INTO THE BOUNDARY LAYER
WILL LEAD TO MOSTLY SUNNY SKIES THROUGH MIDDAY...WITH A SLOW
EXPANSION IN MID AND HIGH LEVEL CLOUDS BY LATE AFTERNOON AS MOISTURE
ALOFT SPREADS INTO THE REGION FROM THE NORTHWEST. WIND GUSTS THIS
MORNING SHOULD DROP OFF RATHER QUICKLY AS THE CENTER OF THE HIGH
MOVES ACROSS THE REGION THIS AFTERNOON.

TEMPS...COLD ADVECTION THROUGH THE AFTERNOON WILL KEEP IT CHILLY...
WITH LOW LEVEL THERMALS SUPPORTING MOS TEMPS IN THE LOWER TO MID
20S.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
ISSUED AT 338 AM EST THU JAN 24 2013

FORECAST CHALLENGES FOCUS ON SNOW CHANCES LATE TONIGHT THROUGH
FRIDAY AS LOW PRESSURE DROPS THROUGH THE GREAT LAKES. STILL SOME
DISCREPANCIES BETWEEN MODELS WITH RESPECT TO MOISTURE AVAILABILITY
AND FORCING ASSOCIATED WITH THE SURFACE WAVE...BUT OVERALL GUIDANCE
IN BETTER AGREEMENT THIS MORNING ON THE MAIN FEATURES.

CLOUDS WILL INCREASE TONIGHT AS THE WAVE APPROACHES FROM THE
NORTHWEST AS ISENTROPIC LIFT AND MOISTURE DEVELOP ALONG A BOUNDARY
OVER THE TENNESSEE VALLEY. SUSPECT MOISTENING OF THE LOWER LEVELS
WILL TAKE SOME TIME AND EFFORT AFTER MIDNIGHT AS SURFACE FLOW
DIRECTION VEERS ONLY SLOWLY FROM EASTERLY TO A MORE S/SE DIRECTION
BY 12Z FRIDAY. HAVE DELAYED ONSET OF POPS UNTIL LATE TONIGHT WITH
THE INITIAL VERY DRY BOUNDARY LAYER. STILL HAVE QUESTIONS AS TO THE
DEPTH OF THE MOISTURE THAT WILL ACCOMPANY THE SYSTEM...AS NO STRONG
GULF FEED WILL BE PRESENT WITH BOUNDARY LAYER WINDS SHIFTING MORE TO
A W/SW FLOW.

BRIEF PERIOD OF ISENTROPIC LIFT DEVELOPS JUST PRIOR TO DAYBREAK AND
EXTENDS THROUGH THE MORNING FRIDAY BEFORE MOISTURE AND MORE
SUBSTANTIAL LIFT SHIFTS EAST INTO THE AFTERNOON. MODEL SOUNDINGS
CONTINUE TO SHOW PRECIP FALLING AS ALL SNOW ACROSS THE FORECAST
AREA...ALTHOUGH HINTS OF A THIN LAYER OF ABOVE FREEZING AIR IN THE
BOUNDARY LAYER BRIEFLY COMING INTO SOUTHERN INDIANA FRIDAY MORNING
HAVE RETURNED. FOCUS OF HEAVIEST SNOWFALL FRIDAY MORNING SHOULD SET
UP OVER THE NORTHEAST HALF OF THE FORECAST AREA WHERE AXIS OF
STRONGEST ISENTROPIC LIFT COMBINES WITH A PERIOD WITH GREATER
VERTICAL VELOCITIES AND A SLIGHTLY DEEPER DENDRITIC GROWTH ZONE.
WITH SNOW RATIOS LIKELY TO BE ELEVATED AND CLOSER TO 15 TO 1 IN
THESE AREAS...FEEL COMFORTABLE PLACING A GENERAL 1 TO 2 INCHES
THROUGH FRIDAY AFTERNOON NORTHEAST OF A ROCKVILLE-MARTINSVILLE-
COLUMBUS LINE WITH AMOUNTS DROPPING OFF QUICKLY TO THE SOUTH OF THAT
LINE. OP GFS EVEN HINTS AT DEVELOPMENT OF A TROWAL OVER OHIO FRIDAY
MORNING WHICH MAY SERVE TO ENHANCE LIFT EVEN A TOUCH MORE OVER
NORTHEAST COUNTIES AND ENABLE A FEW SPOTS FROM KOKOMO TO MUNCIE AND
WINCHESTER TO MAKE A RUN AT 2 TO 3 INCHES FOR A FINAL TALLY.

DRIER AIR WILL ADVECT INTO THE REGION FROM THE WEST RATHER QUICKLY
ON FRIDAY AFTERNOON...SHUTTING OFF LIGHT SNOW FOR MOST OF THE REGION
AND POTENTIALLY EVEN LEADING TO SOME CLEARING LATE. HAVE HELD ONTO
LOW CHANCE POPS HOWEVER THROUGH THE REST OF THE AFTERNOON OVER
NORTHEAST HALF OF THE FORECAST AREA AS A SECONDARY WAVE ALOFT DROPS
THROUGH THE LOWER GREAT LAKES WITH THE SURFACE LOW AND MAY SERVE TO
MAINTAIN SCATTERED LIGHT SNOW SHOWERS OR FLURRIES. ANY LINGERING
FLURRIES WILL END OVER NORTHEAST COUNTIES FRIDAY EVENING WITH HIGH
PRESSURE REESTABLISHING OVER THE REGION FOR THE REMAINDER OF THE
SHORT TERM. THE HIGH WILL BRING ANOTHER SHOT OF COLDER AIR FOR
FRIDAY NIGHT AND SATURDAY...BUT WARM ADVECTION WILL COMMENCE
SATURDAY NIGHT AS THE HIGH MOVES OFF TO THE EAST AND RIDGING ALOFT
EXPANDS INTO THE OHIO VALLEY. MID AND HIGH LEVEL CLOUD COVER WILL
INCREASE LATE SATURDAY NIGHT AS LOW PRESSURE AND AN ASSOCIATED WARM
FRONT LIFTS OUT OF THE CENTRAL PLAINS.

TEMPS...PREFERRED COOLER METMOS GUIDANCE FOR HIGHS FRIDAY AS CLOUDS
AND PRECIP FOR MUCH OF THE DAY FOLLOWED BY COLD ADVECTION. MAVMOS
LOOKED REASONABLE FOR HIGHS SATURDAY PRIMARILY IN THE MID AND UPPER
20S. TRENDED TOWARDS MAVMOS FOR LOWS TONIGHT...THEN GENERALLY WENT
AT OR A COUPLE DEGREES BELOW GUIDANCE FOR FRI/SAT NIGHTS CONSIDERING
MAY HAVE A THIN SNOW COVER IN SOME SPOTS.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
ISSUED AT 327 AM EST THU JAN 24 2013

AN ACTIVE WEATHER PATTERN SETS UP IN THE LONG TERM WITH AN UPPER
TROUGH MOVING THROUGH THE PACIFIC NORTHWEST INTO THE CENTRAL U.S.
THROUGH THE PERIOD. A SERIES OF UPPER SHORTWAVES WILL EJECT FROM THE
UPPER TROUGH AND BRING CHANCES FOR PRECIPITATION TO THE AREA. AT THE
SURFACE A WARM FRONT WILL FORM SOUTH OF THE AREA AND SLOWLY MOVE
NORTH BEFORE THE SURFACE LOW EJECTS FROM THE PLAINS AND TRAVERSES
THE GREAT LAKES. MODELS HAVE SOME MINOR DISAGREEMENTS IN
TIMING/TEMPERATURES EARLY WITH SIGNIFICANT DIFFERENCES BY TUESDAY
NIGHT. GENERALLY ACCEPTED ALLBLEND INITIALIZATION. BIGGEST CHALLENGE
WILL BE PRECIPITATION TYPE FOR SUNDAY-MONDAY. ENTIRE COLUMN IS BELOW
FREEZING SUNDAY MORNING BEFORE PRECIPITATION ARRIVES. BY SUNDAY
AFTERNOON WITH UPPER SHORTWAVE APPROACHING ECMWF AND GFS SHOW AN
INTRUSION OF WARM AIR ALOFT INTO THE SOUTHWEST AND BY SUNDAY NIGHT
THIS MOVES ALL ACROSS THE AREA. MOST OF THE AREA SHOULD SEE A
PROGRESSION FROM A CHANCE FOR SNOW TO A CHANCE FOR SNOW AND SLEET TO
A CHANCE FOR FREEZING RAIN AND SLEET BEFORE TRANSITIONING TO RAIN.
TRIED TO MATCH TRANSITION UP WITH FORECAST SOUNDINGS AND PARTIAL
THICKNESSES...BUT BOTTOM LINE IS MUCH OF THE AREA WILL SEE SOME TYPE
OF WINTRY MIX BEFORE THE TRANSITION TO ALL RAIN WHICH SHOULD OCCUR
BY SOMETIME MONDAY MORNING. THEN CHANCES FOR RAIN WILL BE THE RULE
UNTIL WEDNESDAY WHEN PRECIP TYPE IS UP IN THE AIR BECAUSE OF
AFOREMENTIONED SIGNIFICANT MODEL TEMPERATURE DIFFERENCES.

ANOTHER ITEM OF NOTE IS THE STRENGTH OF THE SYSTEM EJECTING FROM THE
PLAINS TUESDAY/TUESDAY NIGHT. IF THE VERY WARM GFS WERE TO VERIFY
COULD SEE CHANCES FOR THUNDER EEK THIS FAR NORTH. WILL LEAVE OUT FOR
NOW AS ECMWF PAINTS A MUCH DIFFERENT PICTURE AND WOULD RATHER HAVE
SOME AGREEMENT TO INCLUDE THUNDER THIS TIME OF YEAR.

&&

.AVIATION /DISCUSSION FOR 241200Z TAF ISSUANCE/...

ISSUED AT 549 AM EST THU JAN 24 2013

MAINLY VFR CONDITIONS AT THE SITES THROUGH THE PERIOD. THE ONLY
EXCEPTION TO THIS COULD BE OVER THE NEXT COUPLE OF HOURS WITH LAKE
EFFECT SNOW SHOWERS CONTINUING TO DRIFT SOUTH. THESE LEFTOVER ECHOES
COULD BRIEFLY DROP KIND AND KBMG TO MVFR BUT DO NOT EXPECT THIS TO
LAST FOR LONG. COULD ACTUALLY BE FINISHED ISSUANCE TIME AT KIND BUT
MAY INCLUDE A BRIEF MENTION AT KBMG FOR MVFR CEILINGS. AFTER THAT
ONLY SOME CIRRUS EXPECTED THROUGH THE DAY. A CLIPPER SYSTEM WILL
APPROACH NEAR THE END OF THE PERIOD AND BRING LOWERING
CEILINGS...BUT DON/T EXPECT AN IMPACT ON FLYING CONDITIONS UNTIL THE
EXTENDED PORTION OF THE TAF.

WINDS WILL SHIFT FROM NORTHWEST TO NORTHEAST LATER THIS MORNING
BEFORE BECOMING SOUTHEASTERLY THIS EVENING. SPEED GENERALLY 5 TO 12
KTS WITH NO GUSTS EXPECTED.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....CP
AVIATION...CP






AREA FORECAST DISCUSSION

NWS INDIANAPOLIS IN

 403 AM EST THU JAN 24 2013

.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 338 AM EST THU JAN 24 2013

HIGH PRESSURE WILL BRING DRY CHILLY WEATHER TO CENTRAL INDIANA
TODAY. LOW PRESSURE WILL TRACK THROUGH THE GREAT LAKES ON
FRIDAY...WITH SNOW DEVELOPING LATE TONIGHT AND CONTINUING THROUGH
FRIDAY AFTERNOON. A MORE ACTIVE WEATHER PATTERN ARRIVES BEGINNING
SUNDAY AND CONTINUING INTO NEXT WEEK AS A WARM FRONT LIFTS INTO THE
REGION WITH SEVERAL DISTURBANCES TRACKING ALONG IT. AFTER THE
POTENTIAL FOR A WINTRY MIX SUNDAY AFTERNOON AND NIGHT...TEMPERATURES
WILL BE WARM ENOUGH FOR RAIN FOR MUCH OF NEXT WEEK.

&&

.NEAR TERM /TODAY/...
ISSUED AT 338 AM EST THU JAN 24 2013

LAKE EFFECT SNOW SHOWERS AND FLURRIES CONTINUE TO MOVE SOUTH INTO
THE NORTHERN HALF OF THE FORECAST AREA EARLY THIS MORNING. OUTSIDE
OF SNOW SHOWERS/FLURRIES...SKIES WERE PARTLY CLOUDY AS HIGH PRESSURE
BEGINNING TO EXPAND INTO THE REGION. TEMPS WERE FALLING THROUGH THE
20S AND INTO THE TEENS AS COLD ADVECTION ESTABLISHES.

INITIAL FOCUS OF THE NEAR TERM IS ON THE TRANSIENT NATURE OF THE
SNOW SHOWERS AND FLURRIES COMING OUT OF NORTHERN INDIANA AND INTO
NORTHERN COUNTIES. LOW LEVEL FLOW VIA THE MOST RECENT RAP DATA
REMAINS FROM THE NORTHWEST WITH THE VAD PROFILE OFF OF THE KIND
RADAR INDICATING 25-30KTS PRESENT AT ABOUT 3KFT. HAVE SEEN POCKETS
OF HEAVIER SNOW SHOWERS WITHIN A BAND EXTENDING FROM LOGANSPORT
SOUTHEAST THROUGH KOKOMO TO NEAR NOBLESVILLE. EXPECT THESE SNOW
SHOWERS/FLURRIES TO SHIFT WEST AND WEAKEN AS THEY DROP SOUTH WITH
BOUNDARY LAYER FLOW SET TO VEER TO A MORE NORTHERLY DIRECTION
THROUGH DAYBREAK. THERE ARE SIGNS THIS SHIFT IN LOW LEVEL FLOW IS
ALREADY BEGINNING AS AN INCREASINGLY DOMINANT SNOW BAND DEVELOPING
DUE SOUTH OFF OF LAKE MICHIGAN OVER LAKE AND PORTER COS. POTENTIAL
REMAINS FOR THE OUTER FRINGES OF THIS BAND TO WORK ALL THE WAY SOUTH
INTO CARROLL AND TIPPECANOE COS AFTER 09Z AND THROUGH DAYBREAK
BEFORE LOW LEVEL FLOW VEERS FURTHER AND WEAKENS. HAVE HELD ONTO LOW
CHANCE POPS FOR THE NEXT FEW HOURS TO ACCOUNT FOR ONGOING SNOW
SHOWERS...THEN REFOCUSED IT OVER THE NORTHERN WABASH VALLEY TO
ENCOMPASS ABOVE THOUGHTS. COULD SEE A DUSTING IN LOCALIZED AREAS
OVER THE NEXT FEW HOURS TO THE NORTH OF INDY...BUT WITH A DRY SNOW
MOST WILL BE BLOWN AROUND MORE THAN ANYTHING ELSE.

BROAD CANADIAN HIGH PRESSURE WILL THEN TAKE OVER FOR THE REMAINDER
OF THE SHORT TERM...WITH ANOTHER SURGE OF DRY ARCTIC AIR SPREADING
ACROSS THE REGION. DEEP SUBSIDENCE EXPANDING INTO THE BOUNDARY LAYER
WILL LEAD TO MOSTLY SUNNY SKIES THROUGH MIDDAY...WITH A SLOW
EXPANSION IN MID AND HIGH LEVEL CLOUDS BY LATE AFTERNOON AS MOISTURE
ALOFT SPREADS INTO THE REGION FROM THE NORTHWEST. WIND GUSTS THIS
MORNING SHOULD DROP OFF RATHER QUICKLY AS THE CENTER OF THE HIGH
MOVES ACROSS THE REGION THIS AFTERNOON.

TEMPS...COLD ADVECTION THROUGH THE AFTERNOON WILL KEEP IT CHILLY...
WITH LOW LEVEL THERMALS SUPPORTING MOS TEMPS IN THE LOWER TO MID
20S.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
ISSUED AT 338 AM EST THU JAN 24 2013

FORECAST CHALLENGES FOCUS ON SNOW CHANCES LATE TONIGHT THROUGH
FRIDAY AS LOW PRESSURE DROPS THROUGH THE GREAT LAKES. STILL SOME
DISCREPANCIES BETWEEN MODELS WITH RESPECT TO MOISTURE AVAILABILITY
AND FORCING ASSOCIATED WITH THE SURFACE WAVE...BUT OVERALL GUIDANCE
IN BETTER AGREEMENT THIS MORNING ON THE MAIN FEATURES.

CLOUDS WILL INCREASE TONIGHT AS THE WAVE APPROACHES FROM THE
NORTHWEST AS ISENTROPIC LIFT AND MOISTURE DEVELOP ALONG A BOUNDARY
OVER THE TENNESSEE VALLEY. SUSPECT MOISTENING OF THE LOWER LEVELS
WILL TAKE SOME TIME AND EFFORT AFTER MIDNIGHT AS SURFACE FLOW
DIRECTION VEERS ONLY SLOWLY FROM EASTERLY TO A MORE S/SE DIRECTION
BY 12Z FRIDAY. HAVE DELAYED ONSET OF POPS UNTIL LATE TONIGHT WITH
THE INITIAL VERY DRY BOUNDARY LAYER. STILL HAVE QUESTIONS AS TO THE
DEPTH OF THE MOISTURE THAT WILL ACCOMPANY THE SYSTEM...AS NO STRONG
GULF FEED WILL BE PRESENT WITH BOUNDARY LAYER WINDS SHIFTING MORE TO
A W/SW FLOW.

BRIEF PERIOD OF ISENTROPIC LIFT DEVELOPS JUST PRIOR TO DAYBREAK AND
EXTENDS THROUGH THE MORNING FRIDAY BEFORE MOISTURE AND MORE
SUBSTANTIAL LIFT SHIFTS EAST INTO THE AFTERNOON. MODEL SOUNDINGS
CONTINUE TO SHOW PRECIP FALLING AS ALL SNOW ACROSS THE FORECAST
AREA...ALTHOUGH HINTS OF A THIN LAYER OF ABOVE FREEZING AIR IN THE
BOUNDARY LAYER BRIEFLY COMING INTO SOUTHERN INDIANA FRIDAY MORNING
HAVE RETURNED. FOCUS OF HEAVIEST SNOWFALL FRIDAY MORNING SHOULD SET
UP OVER THE NORTHEAST HALF OF THE FORECAST AREA WHERE AXIS OF
STRONGEST ISENTROPIC LIFT COMBINES WITH A PERIOD WITH GREATER
VERTICAL VELOCITIES AND A SLIGHTLY DEEPER DENDRITIC GROWTH ZONE.
WITH SNOW RATIOS LIKELY TO BE ELEVATED AND CLOSER TO 15 TO 1 IN
THESE AREAS...FEEL COMFORTABLE PLACING A GENERAL 1 TO 2 INCHES
THROUGH FRIDAY AFTERNOON NORTHEAST OF A ROCKVILLE-MARTINSVILLE-
COLUMBUS LINE WITH AMOUNTS DROPPING OFF QUICKLY TO THE SOUTH OF THAT
LINE. OP GFS EVEN HINTS AT DEVELOPMENT OF A TROWAL OVER OHIO FRIDAY
MORNING WHICH MAY SERVE TO ENHANCE LIFT EVEN A TOUCH MORE OVER
NORTHEAST COUNTIES AND ENABLE A FEW SPOTS FROM KOKOMO TO MUNCIE AND
WINCHESTER TO MAKE A RUN AT 2 TO 3 INCHES FOR A FINAL TALLY.

DRIER AIR WILL ADVECT INTO THE REGION FROM THE WEST RATHER QUICKLY
ON FRIDAY AFTERNOON...SHUTTING OFF LIGHT SNOW FOR MOST OF THE REGION
AND POTENTIALLY EVEN LEADING TO SOME CLEARING LATE. HAVE HELD ONTO
LOW CHANCE POPS HOWEVER THROUGH THE REST OF THE AFTERNOON OVER
NORTHEAST HALF OF THE FORECAST AREA AS A SECONDARY WAVE ALOFT DROPS
THROUGH THE LOWER GREAT LAKES WITH THE SURFACE LOW AND MAY SERVE TO
MAINTAIN SCATTERED LIGHT SNOW SHOWERS OR FLURRIES. ANY LINGERING
FLURRIES WILL END OVER NORTHEAST COUNTIES FRIDAY EVENING WITH HIGH
PRESSURE REESTABLISHING OVER THE REGION FOR THE REMAINDER OF THE
SHORT TERM. THE HIGH WILL BRING ANOTHER SHOT OF COLDER AIR FOR
FRIDAY NIGHT AND SATURDAY...BUT WARM ADVECTION WILL COMMENCE
SATURDAY NIGHT AS THE HIGH MOVES OFF TO THE EAST AND RIDGING ALOFT
EXPANDS INTO THE OHIO VALLEY. MID AND HIGH LEVEL CLOUD COVER WILL
INCREASE LATE SATURDAY NIGHT AS LOW PRESSURE AND AN ASSOCIATED WARM
FRONT LIFTS OUT OF THE CENTRAL PLAINS.

TEMPS...PREFERRED COOLER METMOS GUIDANCE FOR HIGHS FRIDAY AS CLOUDS
AND PRECIP FOR MUCH OF THE DAY FOLLOWED BY COLD ADVECTION. MAVMOS
LOOKED REASONABLE FOR HIGHS SATURDAY PRIMARILY IN THE MID AND UPPER
20S. TRENDED TOWARDS MAVMOS FOR LOWS TONIGHT...THEN GENERALLY WENT
AT OR A COUPLE DEGREES BELOW GUIDANCE FOR FRI/SAT NIGHTS CONSIDERING
MAY HAVE A THIN SNOW COVER IN SOME SPOTS.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
ISSUED AT 327 AM EST THU JAN 24 2013

AN ACTIVE WEATHER PATTERN SETS UP IN THE LONG TERM WITH AN UPPER
TROUGH MOVING THROUGH THE PACIFIC NORTHWEST INTO THE CENTRAL U.S.
THROUGH THE PERIOD. A SERIES OF UPPER SHORTWAVES WILL EJECT FROM THE
UPPER TROUGH AND BRING CHANCES FOR PRECIPITATION TO THE AREA. AT THE
SURFACE A WARM FRONT WILL FORM SOUTH OF THE AREA AND SLOWLY MOVE
NORTH BEFORE THE SURFACE LOW EJECTS FROM THE PLAINS AND TRAVERSES
THE GREAT LAKES. MODELS HAVE SOME MINOR DISAGREEMENTS IN
TIMING/TEMPERATURES EARLY WITH SIGNIFICANT DIFFERENCES BY TUESDAY
NIGHT. GENERALLY ACCEPTED ALLBLEND INITIALIZATION. BIGGEST CHALLENGE
WILL BE PRECIPITATION TYPE FOR SUNDAY-MONDAY. ENTIRE COLUMN IS BELOW
FREEZING SUNDAY MORNING BEFORE PRECIPITATION ARRIVES. BY SUNDAY
AFTERNOON WITH UPPER SHORTWAVE APPROACHING ECMWF AND GFS SHOW AN
INTRUSION OF WARM AIR ALOFT INTO THE SOUTHWEST AND BY SUNDAY NIGHT
THIS MOVES ALL ACROSS THE AREA. MOST OF THE AREA SHOULD SEE A
PROGRESSION FROM A CHANCE FOR SNOW TO A CHANCE FOR SNOW AND SLEET TO
A CHANCE FOR FREEZING RAIN AND SLEET BEFORE TRANSITIONING TO RAIN.
TRIED TO MATCH TRANSITION UP WITH FORECAST SOUNDINGS AND PARTIAL
THICKNESSES...BUT BOTTOM LINE IS MUCH OF THE AREA WILL SEE SOME TYPE
OF WINTRY MIX BEFORE THE TRANSITION TO ALL RAIN WHICH SHOULD OCCUR
BY SOMETIME MONDAY MORNING. THEN CHANCES FOR RAIN WILL BE THE RULE
UNTIL WEDNESDAY WHEN PRECIP TYPE IS UP IN THE AIR BECAUSE OF
AFOREMENTIONED SIGNIFICANT MODEL TEMPERATURE DIFFERENCES.

ANOTHER ITEM OF NOTE IS THE STRENGTH OF THE SYSTEM EJECTING FROM THE
PLAINS TUESDAY/TUESDAY NIGHT. IF THE VERY WARM GFS WERE TO VERIFY
COULD SEE CHANCES FOR THUNDER EEK THIS FAR NORTH. WILL LEAVE OUT FOR
NOW AS ECMWF PAINTS A MUCH DIFFERENT PICTURE AND WOULD RATHER HAVE
SOME AGREEMENT TO INCLUDE THUNDER THIS TIME OF YEAR.

&&

.AVIATION /DISCUSSION FOR THE 24/09Z TAF UPDATE/...

ISSUED AT 403 AM EST THU JAN 24 2013

A FEW BANDS OF LAKE EFFECT SNOW SHOWERS REMAIN ACROSS THE AREA AND
CLOUDS WITHIN THESE BANDS HAVE CEILINGS IN THE 025-035 FT RANGE. AT
THIS TIME RADAR TRENDS INDICATE POTENTIAL TO IMPACT KBMG AND PERHAPS
CLIP KIND OVER THE NEXT COUPLE HOURS. KLAF COULD GET TAPPED WITH
ANOTHER BAND CURRENTLY COMING OFF THE LAKE...BUT THEY MAY NOT HOLD
TOGETHER THAT FAR SOUTH AS THE WIND SHIFTS. THEREFORE JUST INCLUDED
A TEMPO MVFR GROUP AT KBMG. WIND GUSTS HAVE COME TO AN END AND SO
REMOVED THEM. EXPECT THEM TO VEER TO NORTHEASTERLY THIS MORNING.

CLOUDS WILL FILL IN AGAIN BY EVENING AHEAD OF THE NEXT SYSTEM.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....CP
AVIATION...CP






AREA FORECAST DISCUSSION

NWS INDIANAPOLIS IN

 338 AM EST THU JAN 24 2013

.UPDATE...
THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED
BELOW.

&&

.SYNOPSIS...
ISSUED AT 338 AM EST THU JAN 24 2013

HIGH PRESSURE WILL BRING DRY CHILLY WEATHER TO CENTRAL INDIANA
TODAY. LOW PRESSURE WILL TRACK THROUGH THE GREAT LAKES ON
FRIDAY...WITH SNOW DEVELOPING LATE TONIGHT AND CONTINUING THROUGH
FRIDAY AFTERNOON. A MORE ACTIVE WEATHER PATTERN ARRIVES BEGINNING
SUNDAY AND CONTINUING INTO NEXT WEEK AS A WARM FRONT LIFTS INTO THE
REGION WITH SEVERAL DISTURBANCES TRACKING ALONG IT. AFTER THE
POTENTIAL FOR A WINTRY MIX SUNDAY AFTERNOON AND NIGHT...TEMPERATURES
WILL BE WARM ENOUGH FOR RAIN FOR MUCH OF NEXT WEEK.

&&

.NEAR TERM /TODAY/...
ISSUED AT 338 AM EST THU JAN 24 2013

LAKE EFFECT SNOW SHOWERS AND FLURRIES CONTINUE TO MOVE SOUTH INTO
THE NORTHERN HALF OF THE FORECAST AREA EARLY THIS MORNING. OUTSIDE
OF SNOW SHOWERS/FLURRIES...SKIES WERE PARTLY CLOUDY AS HIGH PRESSURE
BEGINNING TO EXPAND INTO THE REGION. TEMPS WERE FALLING THROUGH THE
20S AND INTO THE TEENS AS COLD ADVECTION ESTABLISHES.

INITIAL FOCUS OF THE NEAR TERM IS ON THE TRANSIENT NATURE OF THE
SNOW SHOWERS AND FLURRIES COMING OUT OF NORTHERN INDIANA AND INTO
NORTHERN COUNTIES. LOW LEVEL FLOW VIA THE MOST RECENT RAP DATA
REMAINS FROM THE NORTHWEST WITH THE VAD PROFILE OFF OF THE KIND
RADAR INDICATING 25-30KTS PRESENT AT ABOUT 3KFT. HAVE SEEN POCKETS
OF HEAVIER SNOW SHOWERS WITHIN A BAND EXTENDING FROM LOGANSPORT
SOUTHEAST THROUGH KOKOMO TO NEAR NOBLESVILLE. EXPECT THESE SNOW
SHOWERS/FLURRIES TO SHIFT WEST AND WEAKEN AS THEY DROP SOUTH WITH
BOUNDARY LAYER FLOW SET TO VEER TO A MORE NORTHERLY DIRECTION
THROUGH DAYBREAK. THERE ARE SIGNS THIS SHIFT IN LOW LEVEL FLOW IS
ALREADY BEGINNING AS AN INCREASINGLY DOMINANT SNOW BAND DEVELOPING
DUE SOUTH OFF OF LAKE MICHIGAN OVER LAKE AND PORTER COS. POTENTIAL
REMAINS FOR THE OUTER FRINGES OF THIS BAND TO WORK ALL THE WAY SOUTH
INTO CARROLL AND TIPPECANOE COS AFTER 09Z AND THROUGH DAYBREAK
BEFORE LOW LEVEL FLOW VEERS FURTHER AND WEAKENS. HAVE HELD ONTO LOW
CHANCE POPS FOR THE NEXT FEW HOURS TO ACCOUNT FOR ONGOING SNOW
SHOWERS...THEN REFOCUSED IT OVER THE NORTHERN WABASH VALLEY TO
ENCOMPASS ABOVE THOUGHTS. COULD SEE A DUSTING IN LOCALIZED AREAS
OVER THE NEXT FEW HOURS TO THE NORTH OF INDY...BUT WITH A DRY SNOW
MOST WILL BE BLOWN AROUND MORE THAN ANYTHING ELSE.

BROAD CANADIAN HIGH PRESSURE WILL THEN TAKE OVER FOR THE REMAINDER
OF THE SHORT TERM...WITH ANOTHER SURGE OF DRY ARCTIC AIR SPREADING
ACROSS THE REGION. DEEP SUBSIDENCE EXPANDING INTO THE BOUNDARY LAYER
WILL LEAD TO MOSTLY SUNNY SKIES THROUGH MIDDAY...WITH A SLOW
EXPANSION IN MID AND HIGH LEVEL CLOUDS BY LATE AFTERNOON AS MOISTURE
ALOFT SPREADS INTO THE REGION FROM THE NORTHWEST. WIND GUSTS THIS
MORNING SHOULD DROP OFF RATHER QUICKLY AS THE CENTER OF THE HIGH
MOVES ACROSS THE REGION THIS AFTERNOON.

TEMPS...COLD ADVECTION THROUGH THE AFTERNOON WILL KEEP IT CHILLY...
WITH LOW LEVEL THERMALS SUPPORTING MOS TEMPS IN THE LOWER TO MID
20S.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
ISSUED AT 338 AM EST THU JAN 24 2013

FORECAST CHALLENGES FOCUS ON SNOW CHANCES LATE TONIGHT THROUGH
FRIDAY AS LOW PRESSURE DROPS THROUGH THE GREAT LAKES. STILL SOME
DISCREPANCIES BETWEEN MODELS WITH RESPECT TO MOISTURE AVAILABILITY
AND FORCING ASSOCIATED WITH THE SURFACE WAVE...BUT OVERALL GUIDANCE
IN BETTER AGREEMENT THIS MORNING ON THE MAIN FEATURES.

CLOUDS WILL INCREASE TONIGHT AS THE WAVE APPROACHES FROM THE
NORTHWEST AS ISENTROPIC LIFT AND MOISTURE DEVELOP ALONG A BOUNDARY
OVER THE TENNESSEE VALLEY. SUSPECT MOISTENING OF THE LOWER LEVELS
WILL TAKE SOME TIME AND EFFORT AFTER MIDNIGHT AS SURFACE FLOW
DIRECTION VEERS ONLY SLOWLY FROM EASTERLY TO A MORE S/SE DIRECTION
BY 12Z FRIDAY. HAVE DELAYED ONSET OF POPS UNTIL LATE TONIGHT WITH
THE INITIAL VERY DRY BOUNDARY LAYER. STILL HAVE QUESTIONS AS TO THE
DEPTH OF THE MOISTURE THAT WILL ACCOMPANY THE SYSTEM...AS NO STRONG
GULF FEED WILL BE PRESENT WITH BOUNDARY LAYER WINDS SHIFTING MORE TO
A W/SW FLOW.

BRIEF PERIOD OF ISENTROPIC LIFT DEVELOPS JUST PRIOR TO DAYBREAK AND
EXTENDS THROUGH THE MORNING FRIDAY BEFORE MOISTURE AND MORE
SUBSTANTIAL LIFT SHIFTS EAST INTO THE AFTERNOON. MODEL SOUNDINGS
CONTINUE TO SHOW PRECIP FALLING AS ALL SNOW ACROSS THE FORECAST
AREA...ALTHOUGH HINTS OF A THIN LAYER OF ABOVE FREEZING AIR IN THE
BOUNDARY LAYER BRIEFLY COMING INTO SOUTHERN INDIANA FRIDAY MORNING
HAVE RETURNED. FOCUS OF HEAVIEST SNOWFALL FRIDAY MORNING SHOULD SET
UP OVER THE NORTHEAST HALF OF THE FORECAST AREA WHERE AXIS OF
STRONGEST ISENTROPIC LIFT COMBINES WITH A PERIOD WITH GREATER
VERTICAL VELOCITIES AND A SLIGHTLY DEEPER DENDRITIC GROWTH ZONE.
WITH SNOW RATIOS LIKELY TO BE ELEVATED AND CLOSER TO 15 TO 1 IN
THESE AREAS...FEEL COMFORTABLE PLACING A GENERAL 1 TO 2 INCHES
THROUGH FRIDAY AFTERNOON NORTHEAST OF A ROCKVILLE-MARTINSVILLE-
COLUMBUS LINE WITH AMOUNTS DROPPING OFF QUICKLY TO THE SOUTH OF THAT
LINE. OP GFS EVEN HINTS AT DEVELOPMENT OF A TROWAL OVER OHIO FRIDAY
MORNING WHICH MAY SERVE TO ENHANCE LIFT EVEN A TOUCH MORE OVER
NORTHEAST COUNTIES AND ENABLE A FEW SPOTS FROM KOKOMO TO MUNCIE AND
WINCHESTER TO MAKE A RUN AT 2 TO 3 INCHES FOR A FINAL TALLY.

DRIER AIR WILL ADVECT INTO THE REGION FROM THE WEST RATHER QUICKLY
ON FRIDAY AFTERNOON...SHUTTING OFF LIGHT SNOW FOR MOST OF THE REGION
AND POTENTIALLY EVEN LEADING TO SOME CLEARING LATE. HAVE HELD ONTO
LOW CHANCE POPS HOWEVER THROUGH THE REST OF THE AFTERNOON OVER
NORTHEAST HALF OF THE FORECAST AREA AS A SECONDARY WAVE ALOFT DROPS
THROUGH THE LOWER GREAT LAKES WITH THE SURFACE LOW AND MAY SERVE TO
MAINTAIN SCATTERED LIGHT SNOW SHOWERS OR FLURRIES. ANY LINGERING
FLURRIES WILL END OVER NORTHEAST COUNTIES FRIDAY EVENING WITH HIGH
PRESSURE REESTABLISHING OVER THE REGION FOR THE REMAINDER OF THE
SHORT TERM. THE HIGH WILL BRING ANOTHER SHOT OF COLDER AIR FOR
FRIDAY NIGHT AND SATURDAY...BUT WARM ADVECTION WILL COMMENCE
SATURDAY NIGHT AS THE HIGH MOVES OFF TO THE EAST AND RIDGING ALOFT
EXPANDS INTO THE OHIO VALLEY. MID AND HIGH LEVEL CLOUD COVER WILL
INCREASE LATE SATURDAY NIGHT AS LOW PRESSURE AND AN ASSOCIATED WARM
FRONT LIFTS OUT OF THE CENTRAL PLAINS.

TEMPS...PREFERRED COOLER METMOS GUIDANCE FOR HIGHS FRIDAY AS CLOUDS
AND PRECIP FOR MUCH OF THE DAY FOLLOWED BY COLD ADVECTION. MAVMOS
LOOKED REASONABLE FOR HIGHS SATURDAY PRIMARILY IN THE MID AND UPPER
20S. TRENDED TOWARDS MAVMOS FOR LOWS TONIGHT...THEN GENERALLY WENT
AT OR A COUPLE DEGREES BELOW GUIDANCE FOR FRI/SAT NIGHTS CONSIDERING
MAY HAVE A THIN SNOW COVER IN SOME SPOTS.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
ISSUED AT 327 AM EST THU JAN 24 2013

AN ACTIVE WEATHER PATTERN SETS UP IN THE LONG TERM WITH AN UPPER
TROUGH MOVING THROUGH THE PACIFIC NORTHWEST INTO THE CENTRAL U.S.
THROUGH THE PERIOD. A SERIES OF UPPER SHORTWAVES WILL EJECT FROM THE
UPPER TROUGH AND BRING CHANCES FOR PRECIPITATION TO THE AREA. AT THE
SURFACE A WARM FRONT WILL FORM SOUTH OF THE AREA AND SLOWLY MOVE
NORTH BEFORE THE SURFACE LOW EJECTS FROM THE PLAINS AND TRAVERSES
THE GREAT LAKES. MODELS HAVE SOME MINOR DISAGREEMENTS IN
TIMING/TEMPERATURES EARLY WITH SIGNIFICANT DIFFERENCES BY TUESDAY
NIGHT. GENERALLY ACCEPTED ALLBLEND INITIALIZATION. BIGGEST CHALLENGE
WILL BE PRECIPITATION TYPE FOR SUNDAY-MONDAY. ENTIRE COLUMN IS BELOW
FREEZING SUNDAY MORNING BEFORE PRECIPITATION ARRIVES. BY SUNDAY
AFTERNOON WITH UPPER SHORTWAVE APPROACHING ECMWF AND GFS SHOW AN
INTRUSION OF WARM AIR ALOFT INTO THE SOUTHWEST AND BY SUNDAY NIGHT
THIS MOVES ALL ACROSS THE AREA. MOST OF THE AREA SHOULD SEE A
PROGRESSION FROM A CHANCE FOR SNOW TO A CHANCE FOR SNOW AND SLEET TO
A CHANCE FOR FREEZING RAIN AND SLEET BEFORE TRANSITIONING TO RAIN.
TRIED TO MATCH TRANSITION UP WITH FORECAST SOUNDINGS AND PARTIAL
THICKNESSES...BUT BOTTOM LINE IS MUCH OF THE AREA WILL SEE SOME TYPE
OF WINTRY MIX BEFORE THE TRANSITION TO ALL RAIN WHICH SHOULD OCCUR
BY SOMETIME MONDAY MORNING. THEN CHANCES FOR RAIN WILL BE THE RULE
UNTIL WEDNESDAY WHEN PRECIP TYPE IS UP IN THE AIR BECAUSE OF
AFOREMENTIONED SIGNIFICANT MODEL TEMPERATURE DIFFERENCES.

ANOTHER ITEM OF NOTE IS THE STRENGTH OF THE SYSTEM EJECTING FROM THE
PLAINS TUESDAY/TUESDAY NIGHT. IF THE VERY WARM GFS WERE TO VERIFY
COULD SEE CHANCES FOR THUNDER EEK THIS FAR NORTH. WILL LEAVE OUT FOR
NOW AS ECMWF PAINTS A MUCH DIFFERENT PICTURE AND WOULD RATHER HAVE
SOME AGREEMENT TO INCLUDE THUNDER THIS TIME OF YEAR.

&&

.AVIATION /DISCUSSION FOR THE 24/06Z TAF ISSUANCE/...
ISSUED AT 1148 PM EST WED JAN 23 2013

WINDS ARE STARTING TO STRENGTHEN AND BECOME NORTHWESTERLY ON THE
BACK SIDE OF A GREAT LAKES DISTURBANCE. ANY SNOW SHOWERS
ASSOCIATED WITH THE LOW HAVE EXITED THE AREA. HOWEVER...WILL LEAVE
MENTION OF SNOW SHOWERS AT KLAF TONIGHT WITH THE PERFECT SET UP
FOR LAKE EFFECT. DO NOT EXPECT CONDITIONS TO FALL BELOW VFR
CATEGORY THOUGH.

WINDS WILL WEAKEN AROUND MID MORNING TOMORROW AND TAKE ON MORE OF A
NORTHEASTERLY COMPONENT. CLOUDS WILL BREAK UP BRIEFLY TOMORROW
AFTERNOON...AND THEN FILL IN AGAIN BY EVENING AHEAD OF THE NEXT
SYSTEM.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....CP
AVIATION...TDUD







AREA FORECAST DISCUSSION

NWS NORTHERN INDIANA

 1242 AM EST THU JAN 24 2013

.AVIATION...
06Z TAFS...A BRIEF LULL IN HEAVIER SNOW SHOWERS AT KSBN...BUT
UPSTREAM RADAR TRENDS SUGGEST MORE ORGANIZED LAKE EFFECT SNOW BAND
ALONG EASTERN SHORE OF LAKE MICHIGAN WILL AFFECT KSBN IN THE 07Z-
09Z TIMEFRAME. PERIODS OF LIFR VSBY RESTRICTIONS ARE LIKELY WITH
THIS BAND...WITH HEAVIEST SNOW LIKELY SHIFTING WEST OF THE
TERMINAL AFTER 09Z. A BRIEF BURST OF HEAVIER SNOW EXPECTED AT KFWA
OVER THE NEXT HOUR...BUT BY 07Z ALL OF LAKE EFFECT SNOW SHOULD
REMAIN SOUTH AND WEST OF THE TERMINAL. LINGERING MVFR CIGS AT KSBN
SHOULD SCATTER BY MID MORNING. QUIET AVIATION WEATHER WILL SET UP
FOR THE REMAINDER OF THIS PERIOD WITH STRONG SUBSIDENCE IN WAKE OF
SYNOPTIC TROUGH. STRONG MID LEVEL WARM ADVECTION IN ADVANCE OF
NEXT UPPER TROUGH WILL ALLOW MID LEVEL CIGS TO OVERSPREAD AREA
TONIGHT...BUT SNOW WITH THIS SYSTEM NOT EXPECTED UNTIL AFTER THE
END OF THIS FORECAST VALID PERIOD.

&&

.UPDATE2...
HAVE ISSUED A LAKE EFFECT SNOW ADVISORY FOR CASS MI IN SOUTHWEST
LOWER MICHIGAN...ALONG WITH ELKHART...MARSHALL...AND STARKE
COUNTIES IN NORTHERN INDIANA. LATEST MARINE OBS SUGGESTING ALONG
SHORE CONVERGENCE BEGINNING TO SHARPEN AND RADAR MOSAIC OVER PAST
HOUR HAS SHOWN BETTER ORGANIZATION OF BANDING ALONG EASTERN
SHORELINE EXTENDING INTO NORTHERN BERRIEN COUNTIES. SHORT TERM
CONCERN THROUGH 07Z WILL BE FOR LOCALLY HIGHER SNOWFALL RATES
ACROSS BERRIEN COUNTY INTO WESTERN CASS MICHIGAN COUNTY...AND THEN
FOCUSING MORE OVER SOUTHWEST BERRIEN AND INTO LAPORTE/ST.JOSEPH
COUNTIES AFTER 07Z. SNOWFALL RATES OF 1 TO 2 INCHES PER HOUR WILL
BE POSSIBLE WITH THIS BAND. STILL CONCERN FOR HEAVIER SNOWFALL
TOTALS LATE TONIGHT ACROSS SOUTHWEST BERRIEN AND NORTHERN
LAPORTE...WHERE THERMAL CONVERGENCE MAY REMAIN ANCHORED FOR A TIME
BEFORE BAND SHIFTS WEST OF THE AREA TOWARD DAYBREAK.

.PREV DISCUSSION... /ISSUED 626 PM EST WED JAN 23 2013/

UPDATE1/AVIATION...

NR TERM MESOSCALE DVLPMNTS WARRANT AN EARLY UPDATE. IMPRESSIVE SW
TROUGH DROPPING SWD OVR NRN WI YIELDING RAPID UPSTREAM LL VEERING
ACRS LK MI AND RAPID COOLING OF CLD TOPS SEEN IN IR. COMPOSITE
RADAR IMAGERY BLOSSOMING IN KIND AND NO DOUBT AUGMENTED W/SEEDER
FEEDER MECHANISM IN PLACE INADV OF MID LVL SW. SHRT TERM RUC ALG
W/LATEST 18Z HIGHRES GUIDANCE QUITE OMINOUS LTR THIS EVENING
W/DVLPMNT OF INTENSE LK SNOW BANDS. AND UNLIKE LAST SVRL
DAYS...MUCH IMPROVED THERMAL ENVIRONMENT W/DEEP...SATURATED ASCENT
INDICATED IN WHAT SHLD EVOLVE TWD A LG INTENSE SINGLE BAND AFT MIDNIGHT.
AS SUCH WILL JUMP ON EXPANDING ADVSY INTO LAPORTE COUNTY.
CONTEMPLATED ADDING ST JOE TOO PER PLACEMENT OF SOME HIGHRES
GUIDANCE HWVR THINK DEEPENING NRLY LL FLW COMPONENT WILL PUSH BAND
WWD. REGARDLESS A SVRL HOUR BURST OF MOD-HVY SNOW XPCD FOR MUCH OF
NW IN/SW MI AS THE EVENING GOES ON. WILL FURTHER MONITOR BAND
EVOLUTION THROUGH THIS EVENING FOR POTENTIAL WARNING CRITERIA
BEING MET.

OTRWS FLIGHT CONDS OBVIOUSLY GOING DOWNHILL AT KSBN OVERNIGHT
W/PRIMARILY IFR CONDS PREVAILING. SHRT PD OF MVFR CIGS AT KFWA
XPCD THIS EVENING AS SFC TROUGH DROPS SWD BUT MAINLY VFR.

PREV DISCUSSION... /ISSUED 337 PM EST WED JAN 23 2013/

SHORT TERM...THROUGH THURSDAY NIGHT.

TWOFOLD FOCUS FOR THIS PACKAGE WITH AREA OF LIGHT SNOW FROM N
ILLINOIS INTO SW PORTIONS OF THE CWA AND REINVIGORATE LAKE EFFECT
POTENTIAL OVER THE NEXT 12 HOURS.

RADAR/SFC OBS/SREF PRODUCTS ALL DEPICT AN AREA OF MID/UPPER LEVEL
FORCING AND LEADING EDGE OF LFQ OF APPROACHING JET STREAK WITH THE
S.W OF INTEREST FOR TONIGHT. THIS IS AIDING IN THE DEVELOPMENT OF A
NARROW BAND OF ACCUMULATING SNOW ACROSS PORTIONS OF N/CNTRL IL. A
FEW REPORTS OF OVER AN INCH HAVE BEEN NOTED WITH THIS FEATURE AS
FAVORABLE DGZ SETUP HAS BEEN UNDERWAY. THIS FEATURE WAS TRACKING SE
ACROSS THE SW PARTS OF THE FORECAST AREA WITH RADAR RETURNS
INCREASING AND SOME FLURRIES BEING REPORTED. SOMEWHAT OF A WEAKENING
TREND HAS BEEN NOTED AS THE AREA BUT STILL EXPECT THE SE TREND TO
CONTINUE AND MAY GIVE A FEW TENTHS OF AN INCH OF SNOW AS IT PASSES.
PREV UPDATE HAD BUMPED POPS TO LIKELY AND WILL LIKELY RUN WITH PRE
1ST PERIOD TO HANDLE.

FOCUS THEN SHIFTS TO LAKE EFFECT FOR THE AREA. INITIAL ENERGY FROM
THE SAME WAVE HAS ALLOWED FOR LAKE EFFECT TO EXPAND ACROSS MUCH OF
NORTHERN BERRIEN COUNTY OVER THE PAST COUPLE OF HOURS. SOCIAL MEDIA
REPORT OF 1 TO 2 INCHES OF NEW SNOW SEEN WITH MUCH LARGER SNOWFLAKES
THAN EARLIER EVENT. THESE SNOW SHOWERS SHOULD CONTINUE AND WITH TIME
EXPAND AS WAVE PASSES BY AND INCREASES LAKE EFFECT BAND COVERAGE AND
INTENSITY AS WELL AS BEGINS TO ALLOW FOR TRANSIENT STATE TONIGHT.
ALL HI RES MODELS STILL DEPICT AN INTERESTING SCENARIO TONIGHT WITH
BANDS BECOMING MORE FOCUSED ACROSS CNTRL/S LWR MI AND EVENTUALLY
DROPPING SOUTH AND WEST AS FLOW BECOMES MORE NW AND EVENTUALLY N
OVERNIGHT. EAST AND SOUTH EXTENSION OF THE SNOW SHOWERS REMAINS
TOUGH TO DETERMINE WITH SREF BRINGING A BURST OF LIGHT TO MODERATE
SNOW TO MUCH OF THE NORTHERN HALF OF THE AREA LATE EVE INTO THE
OVERNIGHT HOURS. NAM/RAP/WRF ALL KEEP THE ACTIVITY MORE CONFINED TO
WITHIN A FEW COUNTIES INLAND. HAVE TRIED TO CAPTURE TRENDS THE BEST
WITHOUT GOING OVERBOARD GIVEN HI BUST POTENTIAL ON EITHER SIDE.
SEEING HOW MUCH FORCING HAS BEEN ASSOCIATED WITH THIS WAVE ALREADY
AND A SMALL WINDOW OF SEMI FAVORABLE DGZ POSITIONING...COULD SEE
SOME AREAS PICKUP A QUICK INCH OR TWO OF SNOW AS THE BAND PASSES.
WENT WITH HPC QPF WHICH WAS REASONABLE AND ALIGNED NICELY WITH
FAVORED LAKE EFFECT AREAS. GIVEN TRENDS SO FAR AND DISCUSSION WITH
EVE SHIFT...WILL HESITANTLY DROP CASS COUNTY FROM THE ADVISORY.
WHILE THEY MAY BE AFFECTED BY THE SNOWBAND FOR A PERIOD OF TIME THE
OVERALL RISK SEEMS TO BE DIMINISHING WITH MAIN FOCUS FOR THE TIME
BEING ON N BERRIEN COUNTY.

BY THURSDAY MORNING...BAND WILL LIKELY BE ORIENTED NORTH TO SOUTH
AND MOVING WEST AS FLOW BECOMES NE WITH TIME. IN ADDITION...A FEW OF
THE HIGH RES MODELS SHOW A MESOLOW SETTING UP QUICKLY ACROSS N LK MI
AND DROPPING SOUTH INTO S LK MI TOWARDS 12Z. HAVE ADJUSTED POPS TO
REFLECT SLIGHTLY SLOWER TREND IN THE MORNING. CLEARING SKIES SHOULD
RAPIDLY TAKE SHAPE IN THE MORNING EAST OF THE BAND. THIS WILL BE
SHORT LIVED AS NORTHERN AND SOUTHERN STREAM ENERGY BEGIN TO CONVERGE
ON THE AREA. DRY CONDITIONS SHOULD HOLD INTO MUCH OF THURS NGT
BEFORE INCREASED FORCING MOVE IN FROM THE NW LATE THURS NGT. GIVEN
FOCUS ON FIRST PERIOD OR TWO OF FORECAST AND TREND OF MODELS HAVING
A SLOWER ARRIVAL TO ANY PRECIP HAVE KEPT THURS NGT UNTOUCHED WRT
POPS AND DEFER TO OVERNIGHT SHIFT TO LOOK AT AGAIN. ANY ACCUMS
TOWARDS FRI AM WOULD APPEAR TO BE ON THE LIGHT SIDE.

LONG TERM...
FRIDAY THROUGH WEDNESDAY...CHALLENGES THIS PACKAGE INCLUDE THE
AMOUNT OF SNOW FRIDAY WITH A WEAK UPPER LEVEL SYSTEM AND THE TIMING
AND TYPES OF PRECIPITATION NEXT WEEK IN AN UNSETTLED PATTERN. FOR
THIS PACKAGE...FAVOR THE ECMWF A LITTLE MORE THAN THE GFS DUE TO RUN
TO RUN CONSISTENCY OF THE ECMWF. THE 06Z AND 18Z GFS RUNS HAVE BEEN
VERY INCONSISTENT WITH THE 12Z AND 00Z RUN. THE 12Z GFS RUN HAS
TRENDED MUCH WARMER TUESDAY FROM THE 06Z RUN AND NOW SUPPORTS THE
ECMWF. FOR FRIDAY...THE ONGOING TIMING AND AMOUNTS OF SNOW LOOK
GOOD. THE GARCIA METHOD WITH MIXING RATIOS TOPPING 3 G/KG SUPPORT
SNOW AMOUNTS OF GENERALLY 1 TO 3 INCHES GIVEN SOMEWHAT LIMITED
ISENTROPIC LIFT...BUT FAVORABLE JET DYNAMICS AND AGEOSTROPHIC
CIRCULATION. COLDER AIR WILL SPREAD BACK OVER THE REGION WITH MORE
LAKE EFFECT SNOW EXPECTED FRIDAY NIGHT INTO SATURDAY. EXTENDED THE
TIMING OF THE LAKE EFFECT SNOW A LITTLE MORE INTO SATURDAY GIVEN A
FAVORABLE FETCH OVER THE LONG AXIS OF THE LAKE. FOR SUNDAY NIGHT
INTO MONDAY...ADDED FREEZING RAIN AND SLEET GIVEN THERMAL PROFILES.
UPDATED THE HAZARDOUS WEATHER OUTLOOK IN THIS REGARD FOR THE
POTENTIAL FOR THIS WINTRY MIX WITH TRAVEL ISSUES POSSIBLE. TRENDED
TUESDAY A LITTLE WARMER GIVEN WARM TEMPERATURES AT 850 MB AND GOOD
MIXING EXPECTED. BELIEVE SNOW COVER SHOULD BE VERY LIMITED BY
TUESDAY AFTERNOON AND SHOULD NOT BE AN ISSUE IN KEEP TEMPERATURES
FROM CLIMBING WELL INTO THE 40S.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ THIS MORNING
     FOR INZ005-012-014.

     LAKE EFFECT SNOW WARNING UNTIL 7 AM EST /6 AM CST/ THIS MORNING
     FOR INZ003-004.

MI...LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST THIS MORNING FOR MIZ078.

     LAKE EFFECT SNOW WARNING UNTIL 7 AM EST THIS MORNING FOR MIZ077.

OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR LMZ043-046.

&&

$$

SHORT TERM...FISHER
LONG TERM...SKIPPER
UPDATE1/AVIATION...T
UPDATE2...MARSILI
AVIATION...MARSILI







AREA FORECAST DISCUSSION

NWS QUAD CITIES IA IL

 1124 PM CST WED JAN 23 2013

.AVIATION...
VFR CONDITIONS TO PREVAIL THROUGH THURSDAY EVENING WITH MAINLY JUST
SOME HIGH CLOUDINESS AS SFC HIGH PRESSURE REMAINS IN CONTROL.
GUSTY NORTH WINDS TO GRADUALLY DIMINISH BELOW 10 KTS THURSDAY AM
THEN VEER TO THE S/SE DURING THE AFTN THROUGH EVE AS THE HIGH
PRESSURE SYSTEM BEGINS TO MOVE AWAY FROM REGION. JUST BEYOND THE
END OF THE TAF CYCLE... OR LATE THURSDAY NIGHT INTO FRIDAY AM... LIGHT
SNOW IS EXPECTED TO DEVELOP OVER THE REGION WITH WARM ADVECTION
ALOFT AS STORM SYSTEM PASSES TO OUR NORTH... WHILE ANOTHER PASSES TO
THE SOUTH. CONDITIONS LIKELY TO LOWER TO MVFR IN THE LIGHT SNOW WITH
IFR POSSIBLE.

&&

.PREV DISCUSSION... /ISSUED 940 PM CST WED JAN 23 2013/

UPDATE...
FINAL BAND OF FLURRIES AND SNOW SHOWERS (ROUGHLY 30 MI WIDE) WITH
LEADING EDGE FROM NEAR CLINTON TO STERLING WILL CONTINUE TO DIVE
SOUTH NEXT FEW HRS EXITING CWA BY 07Z-08Z. THIS MAY BRING QUICK
DUSTING OF ACCUM TO FEW LOCATIONS NEAR TO EAST OF MISSISSIPPI RVR.
SKIES THEN CLEAR IN WAKE OF SYSTEM OVERNIGHT WITH JUST SOME HIGH
THIN CLOUDS. AS FOR WIND CHILL ADVISORY FOR PORTIONS OF NORTHEAST
IA AND NORTHWEST IL... IT WENT INTO EFFECT AT 8 PM BUT WE HAVE
NOT BEEN CLOSE TO MEETING CRITERIA THUS FAR AS FCST TEMPS HAVE
BEEN RUNNING COLDER THAN OBS. TO AVOID ANY CONFUSION I HAVE LEFT
ADVISORY IN EFFECT HOWEVER I ADJUSTED WORDING IN ADVISORY TO
HIGHLIGHT THE TIME PERIOD LATER TONIGHT THROUGH MID AM THU (08Z-
15Z) AS BEING THE MAIN WINDOW FOR THE DANGEROUSLY COLD WIND CHILLS
OF AROUND 20 BELOW ZERO. AS FOR LOWS... TWEAKED UP 1-2 DEGS IN MOST
PLACES WITH FCST RUNNING COLDER THAN OBS. LATEST RAP MODEL 2M TEMPS
VERIFYING WELL WITH OBS AT 03Z AND SUPPORT LOWS AROUND ZERO TO
5 BELOW NORTH OF I-80 TO SINGLE DIGITS ABOVE ZERO TO THE SOUTH.
GRIDS/ZFP HAVE BEEN SENT.

PREV DISCUSSION... /ISSUED 656 PM CST WED JAN 23 2013/

UPDATE...
BASED ON RADAR/SATL TRENDS AND OBS UPDATED FCST TO INCREASE CLOUD
COVER AND MENTION ISOLD SNOW SHOWERS REST OF THE EVE FOR PORTIONS
OF NORTHEAST IA AND NORTHWEST IL.

PREV DISCUSSION... /ISSUED 258 PM CST WED JAN 23 2013/

SYNOPSIS...
A COLD FRONT WAS PUSHING ACROSS EASTERN IA AT MID AFTERNOON WITH
NORTHWEST WINDS GUSTING TO 25 TO 30 KNOTS BEHIND THE FRONT. STRONG
COLD AIR ADVECTION WAS TAKING PLACE WITH THE PASSAGE OF THE FRONT
AS TEMPERATURES HAVE FALLEN INTO THE TEENS IN NORTHERN IA AND
SINGLE DIGITS IN SOUTHERN MN. EVEN COLDER FARTHER NORTH WITH
READINGS BELOW ZERO ACROSS ND AND NORTHERN AND CENTRAL MN.
CURRENTLY IN THE DVN CWA TEMPERATURES RANGED FROM ABOUT 20 FAR
NORTH TO LOWER TO MID 30S FAR SOUTH.

A NARROW BAND OF DENDRITIC SNOW THIS MORNING ACCUMULATED TO 0.5
TO 2.0 INCHES ROUGHLY ALONG HIGHWAY 20. THIS BAND OF SNOW
OCCURRED ON THE CYCLONIC SIDE OF A NARROW 100 KNOT MID LEVEL WIND
MAXIMUM WHERE VERTICAL MOTION WAS ENHANCED AND WAS CONCENTRATED IN
A TIGHT BAROCLINIC ZONE. 850 MB TEMPERATURES AT 12Z WERE -20C AT
KGRB AND +1C AT KOMA. SOUNDINGS INDICATED SATURATION OCCURRED IN
THE FAVORED DENDRITIC GROWTH ZONE OF -12 TO -18C. SNOW/LIQUID
RATIOS WERE AN INCREDIBLE 120:1 BASED ON OBSERVER MEASUREMENTS.

HAASE

SHORT TERM...TONIGHT AND THURSDAY...
HEADLINES...HAVE ALREADY ISSUED A WIND CHILL ADVISORY FOR PORTIONS
OF OUR NORTHERN CWA 8 PM THIS EVENING THROUGH 9 AM THURSDAY FOR
WIND CHILLS OF 20 TO 25 BELOW ZERO.

TONIGHT...FORECAST FOCUS ON TEMPERATURES AS COLD FRONT BRINGS
COLDER WEATHER INTO THE REGION. FREQUENT WIND GUSTS TO 25 TO 30
WITH A FEW GUSTS POSSIBLY TO 35 MPH WILL OCCUR INTO THE EVENING
HOURS. THESE WINDS WILL DIMINISH AFTER MIDNIGHT TO ABOUT 10 MPH AS
1044 MB HIGH PRESSURE BUILDS INTO THE REGION OUT OF CANADA. SKIES
WILL CONTINUE TO CLEAR OVERNIGHT. OPERATIONAL MODELS HAVE LATCHED
ONTO THE COLDER AIRMASS AND GUIDANCE IS NOW COLDER THAN PREVIOUS
RUNS. IN ADDITION...THE FRESH SNOW THAT FELL IN OUR FAR NORTH THIS
MORNING WILL HELP TO LOWER THE TEMPERATURE EVEN MORE. THEREFORE
WILL FORECAST MINIMUM TEMPERATURES AS LOW AS 7 BELOW IN OUR FAR
NORTH TO 5 ABOVE SOUTH. THIS WILL GIVE WIND CHILLS OF 15 TO 25
BELOW ZERO ALONG AND NORTH OF INTERSTATE 80.

THURSDAY...FRIGID WIND CHILLS WILL CONTINUE THROUGH MID MORNING
AND THEN IMPROVING CONDITIONS AS WINDS GO LESS THAN 10 MPH AS THE
CENTER OF THE HIGH GETS CLOSER. IN THE AFTERNOON THE HIGH PRESSURE
WILL PUSH INTO THE OHIO VALLEY. THIS WILL ALLOW LOW LEVEL WARM AIR
ADVECTION TO KICK IN AND MID/HIGH LEVEL CLOUDS SHOULD INCREASE FROM
WEST TO EAST. WILL BE A COLD DAY WITH MAXIMUM TEMPERATURES IN THE
TEENS NORTH TO LOWER 20S SOUTH. WHERE THE FRESH SNOW FELL ACROSS
PORTIONS OF HIGHWAY 20 THIS MORNING THOSE AREAS MAY STRUGGLE TO EVEN
REACH THE TEENS ON THURSDAY.

HAASE

LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY...
MODELS ARE CONSISTENT IN BRINGING A SHORT WAVE OUT OF THE NORTHERN
PLAINS AND INTO THE WESTERN GREAT LAKES BY 12Z FRIDAY. MODEL QPF
PROGS SHOW AN AREA OF LIGHT PRECIPITATION ASSOCIATED WITH THE SHORT
WAVE FROM EASTERN IOWA INTO NORTHERN ILLINOIS LATE THURSDAY NIGHT.
THE EXCEPTION TO THIS IS THE NAM SOLUTION WHICH KEEPS THE
PRECIPITATION CLOSER TO THE S/W OVER MN AND WI.  IT APPEARS THE NAMS
LACK OF PCPN AWAY FROM THE S/W MAY BE DUE TO THE NAM HOLDING ON TO A
LAYER OF NEAR SURFACE DRY AIR LONGER THAN THE OTHER OPERATIONAL
MODELS.  SINCE FORCING ON THE NAM LOOKS SIMILAR TO THE OTHER MODELS
WILL STEER AWAY FROM IT/S DRIER SOLUTION AND LEAN TOWARD THE
CONSENSUS.  LIGHT SNOW IS EXPECTED TO SPREAD OVER THE AREA BEGINNING
LATE THURSDAY EVENING AND CONTINUE OVERNIGHT.  TIME HEIGHT PLOTS
WERE SHOWING A BRIEF PERIOD...1 TO 2 HOURS...OF OPTIMAL LIFT IN THE
DENDRITIC ZONE AFTER MIDNIGHT WHICH SHOULD PRODUCE MOST OF THE
ACCUMULATIONS.  WITH WATER EQUIVALENT AMOUNTS EXPECTED TO BE AROUND
A TENTH OF AN INCH...ESPECIALLY OVER NORTHWEST ILLINOIS AND SNOW
RATIOS IN THE 15 TO 20:1 RANGE...WE SHOULD SEE ACCUMULATIONS IN THE
1 TO 2 INCH RANGE ALONG AND EAST OF THE MISSISSIPPI RIVER BY 6 AM
FRIDAY.  THE SNOW SHOULD END QUICKLY FROM WEST TO EAST FRIDAY
MORNING WITH ONLY SOME LINGERING FLURRIES POSSIBLE IN THE FAR EAST
DURING THE AFTERNOON.  AFTER MORNING LOWS IN THE TEENS
FRIDAY...AFTERNOON SUN AND SOME MIXING SHOULD HELP TEMPERATURES
REBOUND INTO THE 20S.

HIGH PRESSURE MOVING INTO CENTRAL IOWA BY SATURDAY MORNING AND CLEAR
SKIES SHOULD ALLOW GOOD RADIATIONAL COOLING. KEPT MINS IN THE SINGLE
DIGITS OVER THE NORTHWEST HALF OF THE AREA SATURDAY MORNING AND
AROUND 10 IN THE SOUTHEAST.  THESE TEMPERATURES MAYBE ON THE WARM
SIDE IF THE SNOWFALL PANS OUT THURSDAY NIGHT.

SATURDAY WILL BE A TRANSITION DAY WITH THE WESTERN U.S. UPPER RIDGE
MOVING EAST INTO THE  CENTRAL U.S. AND A TROF DEVELOPING OVER THE
WEST BY SATURDAY EVENING.  LATE SATURDAY NIGHT A S/W EJECTS OUT OF
THE WESTERN TROF AND MOVES THROUGH THE MID MISSISSIPPI VALLEY
SUNDAY.  THE MEDIUM RANGE MODELS ALL SHOW THIS SCENARIO BUT THERE
ARE TIMING DIFFERENCES WITH THE ECMWF THE SLOWEST AND THE GFS ONE OF
THE FASTER SOLUTIONS.  DESPITE THE TIMING ISSUES...THE MODELS ALL
SUGGEST A MIXED PRECIP EVENT SUNDAY AND SUNDAY NIGHT.  THE PRECIP
COULD BEGIN IN THE SOUTHWEST EARLY SUNDAY MORNING AND SPREAD
NORTHEAST DURING THE DAY WITH THE PRECIP TYPE INCLUDING
SNOW...FREEZING RAIN...SLEET AND RAIN.

FOR MONDAY AND TUESDAY UNSETTLED WEATHER WILL STAY OVER THE AREA AS THE
UPPER FLOW BECOMES SOUTHWESTERLY EARLY IN THE PERIOD CAUSING A WARM
FRONT TO LIFT NORTH AND THEN STALL OVER OR JUST SOUTH OF THE
FORECAST AREA.  A WAVE IS THEN EXPECTED TO LIFT NORTHEAST ALONG THE
BOUNDARY TUESDAY.  THIS PATTERN SHOULD KEEP A MIX OF PRECIPITATION
OVER THE AREA WITH MAINLY RAIN FAVORED IN THE SOUTH AND A MIX OF
RAIN AND SNOW OVER THE NORTH MONDAY AND MONDAY NIGHT WITH MAINLY
RAIN OVER THE ENTIRE AREA TUESDAY.   THUNDERSTORMS OVER THE SOUTH
AREN/T OUT OF THE QUESTION TUESDAY AS THE SURFACE LOW MOVES THROUGH
OR NEAR THE FORECAST AREA.  THE STALLED BOUNDARY WILL ALSO BRING
MILD TEMPERATURES TO THE REGION WITH 30S AND 40S EXPECTED MONDAY AND
40S AND LOW 50S ON TUESDAY.

COLDER AIR IS EXPECTED TO PUSH BACK INTO THE REGION TUESDAY NIGHT
AND WEDNESDAY BEHIND THE DEPARTING SURFACE WAVE.

DLF

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WIND CHILL ADVISORY UNTIL 9 AM CST THURSDAY FOR BENTON-BUCHANAN-
     DELAWARE-DUBUQUE-JACKSON-JONES-LINN.

IL...WIND CHILL ADVISORY UNTIL 9 AM CST THURSDAY FOR JO DAVIESS.

MO...NONE.
&&

$$





AREA FORECAST DISCUSSION

NWS DODGE CITY KS

 217 PM CST THU JAN 24 2013

...UPDATE TO LONG TERM...

.SYNOPSIS...
ISSUED AT 1139 AM CST THU JAN 24 2013

AT 12Z THURSDAY A 500MB TROUGH WAS LOCATED ACROSS WESTERN
MONTANA/NORTHERN IDAHO. THIS UPPER LEVEL TROUGH WAS ASSOCIATED
WITH A +120KT 250MB JET. EAST OF THIS UPPER LEVEL SYSTEM AT THE
850MB LEVEL A WEDGE OF WARM AIR WAS EVIDENT FROM EASTERN MONTANA
SOUTHWARD INTO WYOMING. THE 850MB TEMPERATURE AT GLASGOW, MT AT
12Z THURSDAY WAS +6C. AT THE SURFACE A COLD FRONT EXTENDED FROM
EASTERN MONTANA SOUTHWARD ACROSS WYOMING AND EASTERN COLORADO INTO
THE PANHANDLE OF TEXAS. NORTHEAST OF THIS FRONT SOME WARM MOIST
AIR WAS BEING ADVECTED INTO SOUTHWEST KANSAS AND HAD RESULTED IN
WIDESPREAD STATUS. DODGE CITY SOUNDING AT 12Z INDICATED THIS
STATUS DECK WAS MAINLY CONFINED TO THE 900MB TO 850MB LEVEL. BELOW
THIS STATUS DECK SURFACE TEMPERATURES AS OF 17Z WERE MAINLY IN THE
20S.

&&

.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 143 PM CST THU JAN 24 2013

12Z NAM AND 12Z GFS VERIFIED FAIRLY WELL AT 18Z WITH THE LOCATION
OF AN UPPER LEVEL TROUGH THAT WAS LOCATED OVER WESTERN
MONTANA/NORTHERN IDAHO EARLIER THIS MORNING. THE NAM AND GFS
REMAINED IN GOOD AGREEMENT MOVING THIS UPPER LEVEL TROUGH ACROSS
THE NORTHERN PLAINS DURING THE OVERNIGHT HOURS AND BY EARLY FRIDAY
MORNING PLACED THIS UPPER TROUGH OVER THE WESTERN GREAT LAKES
REGION. AS THIS SYSTEM CROSSES THE NORTHERN PLAINS OVERNIGHT, A
COLD FRONT WILL DROP SOUTH TOWARDS THE CENTRAL PLAINS. AS THIS
FRONT APPROACHES KANSAS EARLY TONIGHT...A WEDGE OF WARMER AIR IN
THE LOWER LEVELS THAT WAS LOCATED AHEAD OF THIS COLD FRONT OVER
EASTERN WYOMING/MONTANA AT 12Z THURSDAY WILL DROP SOUTHEAST INTO
WESTERN KANSAS. GIVEN THIS WARMER AIR SPREADING INTO THE AREA
OVERNIGHT ALONG WITH MOSTLY CLOUDY SKIES, IT STILL APPEARS THE
PREVIOUS FORECAST IS ON TRACK KEEPING THE DIURNAL CHANGE IN
TEMPERATURES BETWEEN EARLIER TODAY AND OVERNIGHT SMALL. BASED ON
EXPECTED HIGHS TODAY WILL FAVOR OVERNIGHT LOWS MAINLY IN THE LOW
TO MID 20S.

ON FRIDAY AN UPPER LEVEL RIDGE AXIS WILL BUILD ACROSS THE ROCKIES
AS THE UPPER LEVEL TROUGH CROSSES THE GREAT LAKES AND OHIO VALLEY.
850MB TEMPERATURES FRIDAY AFTERNOON ARE FORECAST TO RANGE FROM
+4C TO +6C. 925MB TEMPERATURES WILL AVERAGE BETWEEN +8 AND +12C.
USING THESE AS A GUIDE FOR HIGHS FRIDAY AFTERNOON IT WOULD APPEAR
TEMPERATURES SHOULD REBOUND BACK AT LEAST INTO THE LOWER 50S.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 208 PM CST THU JAN 24 2013

MEDIUM RANGE MODELS CONTINUE TO INDICATE AN UPPER LEVEL TROUGH OF
LOW PRESSURE PUSHING ASHORE INTO SOUTHERN CALIFORNIA LATE FRIDAY
NIGHT THEN LIFTING NORTHEASTWARD ACROSS THE CENTRAL AND SOUTHERN
ROCKIES SATURDAY. THIS WILL BRING THE NEXT CHANCE FOR PRECIP TO
CENTRAL AND PORTIONS OF WESTERN KANSAS SATURDAY EVENING INTO EARLY
SUNDAY. A DEVELOPING SOUTH TO SOUTHEASTERLY LOW LEVEL FLOW WILL
ADVECT SOME INCREASED MOISTURE NORTHWARD INTO WESTERN KANSAS WITH
H85 DEWPOINTS CLIMBING ABOVE 0C LATE SATURDAY AFTERNOON. INCREASED
DIVERGENCE ALOFT COMBINED WITH A MODEST +70KT UPPER LEVEL JET WILL
PROVIDE ENOUGH FAVORABLE DYNAMIC SUPPORT TO SUPPORT PRECIP
DEVELOPMENT FROM THE SOUTH PLAINS OF THE TEXAS PANHANDLE AND
WESTERN OKLAHOMA NORTHEAST INTO KANSAS. GFS AND ECMWF MODEL
SOUNDINGS SHOW A LACK OF INSTABILITY WITH ENVIRONMENTAL PROFILES
REMAINING ABOVE FREEZING GENERALLY BELOW H7 SUGGESTING A LIGHT TO
MODERATE RAIN EVENT, PARTICULARLY WITH LOW QPF AND PW VALUES OF
LESS THAN ONE INCH. ANY PRECIP WILL COME TO AN END WEST TO EAST BY
LATE SUNDAY AFTERNOON. DRIER CONDITIONS ARE THEN EXPECTED INTO THE
EARLY PART OF NEXT WEEK AS A DEEP UPPER LEVEL TROUGH BEGINS TO DIG
SOUTHEAST ACROSS THE FAR WESTERN CONUS. THIS SYSTEM COULD PROVIDE
SOME CHANCE FOR PRECIP ACROSS THE WESTERN HIGH PLAINS IN THE
TUESDAY/WEDNESDAY TIME FRAME.

ABOVE NORMAL TEMPERATURES ARE EXPECTED SATURDAY AS SURFACE
TROUGHING IN EASTERN COLORADO CONTINUES TO HELP INFLUENCE A
LOW LEVEL SOUTHERLY FLOW INTO WESTERN KANSAS. THIS WILL DRAW
SLIGHTLY WARMER AIR FURTHER NORTH INTO WESTERN KANSAS WITH THE
GEM, GFS, AND ECMWF SHOWING H85 TEMPERATURES RANGING FROM THE
MID SINGLE DIGITS(C) ACROSS CENTRAL KANSAS TO NEAR 10C CLOSE
TO THE COLORADO BORDER. COMBINED WITH DECREASING CLOUDS, LOOK FOR
WIDESPREAD 50S(F) ACROSS SOUTHWEST KANSAS WITH NEAR 60F POSSIBLE
IN EXTREME SOUTHWEST KANSAS. THE SURFACE TROUGH IS PROJECTED TO
EDGE SLOWLY EAST INTO FAR WESTERN KANSAS SUNDAY INFLUENCING MORE
OF A WEST TO SOUTHWESTERLY DOWNSLOPE FLOW ACROSS WESTERN KANSAS
LEADING TO EVEN WARMER TEMPERATURES SUNDAY AFTERNOON. EXPECT HIGHS
WELL UP INTO THE 50S(F) WITH LOWER TO MID 60S(F) POSSIBLE ALONG
THE OKLAHOMA BORDER IN FAR SOUTHWEST KANSAS. THE WARMING TREND
WILL CONTINUE INTO MONDAY AS ANOTHER SURFACE LOW DEVELOPS LEE OF
THE ROCKIES IN ADVANCE OF A STRONG UPPER LEVEL TROUGH APPROACHING
FROM THE WEST. WIDESPREAD 60S(F) ARE LIKELY MONDAY AFTERNOON WITH
NEAR 70F A POSSIBILITY IN SOME LOCATIONS. A SURGE OF COLD AIR
BEHIND A FRONTAL PASSAGE WILL LOWER HIGH TEMPERATURES TUESDAY
THROUGH THE END OF THE PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1139 AM CST THU JAN 24 2013

12Z BUFR SOUNDINGS SUGGESTING MVFR STATUS DECK WILL LINGER ACROSS
ALL THE TAF SITES THROUGH AT LEAST THE LATE AFTERNOON. HRRR WAS A
LITTLE MORE PESSIMISTIC KEEPING THE STATUS IN AT GCK UNTIL AROUND
00Z. AT THIS TIME GIVEN THE LATEST SATELLITE LOOP WHICH SUGGESTED
SOME MID-HIGH LEVEL MOISTURE WAS ALREADY BEGINNING TO SPREAD INTO
WESTERN KANSAS LATE THIS MORNING HAVE DECIDED TO FOLLOW THE SLOWER
EROSION OF THE MVFR CIGS. AS A RESULT EXPECT CIGS TO REMAIN AS IS
UNTIL 00Z FRIDAY AT GCK, 03Z AT DDC AND HYS. EASTERLY SURFACE
WINDS AT 10KTS OR LESS WILL GRADUALLY SHIFT TO THE SOUTH/SOUTHWEST
BY LATE DAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  23  53  27  55 /   0   0   0  10
GCK  23  53  28  57 /   0   0   0  10
EHA  28  54  32  58 /   0   0   0  10
LBL  25  54  29  57 /   0   0   0  10
HYS  21  52  26  54 /   0   0   0   0
P28  23  55  26  54 /   0   0   0   0

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...BURGERT
SHORT TERM...BURGERT
LONG TERM...JJOHNSON
AVIATION...BURGERT







AREA FORECAST DISCUSSION

NWS DODGE CITY KS

 146 PM CST THU JAN 24 2013

...UPDATED SHORT TERM DISCUSSION...

.SYNOPSIS...
ISSUED AT 1139 AM CST THU JAN 24 2013

AT 12Z THURSDAY A 500MB TROUGH WAS LOCATED ACROSS WESTERN
MONTANA/NORTHERN IDAHO. THIS UPPER LEVEL TROUGH WAS ASSOCIATED
WITH A +120KT 250MB JET. EAST OF THIS UPPER LEVEL SYSTEM AT THE
850MB LEVEL A WEDGE OF WARM AIR WAS EVIDENT FROM EASTERN MONTANA
SOUTHWARD INTO WYOMING. THE 850MB TEMPERATURE AT GLASGOW, MT AT
12Z THURSDAY WAS +6C. AT THE SURFACE A COLD FRONT EXTENDED FROM
EASTERN MONTANA SOUTHWARD ACROSS WYOMING AND EASTERN COLORADO INTO
THE PANHANDLE OF TEXAS. NORTHEAST OF THIS FRONT SOME WARM MOIST
AIR WAS BEING ADVECTED INTO SOUTHWEST KANSAS AND HAD RESULTED IN
WIDESPREAD STATUS. DODGE CITY SOUNDING AT 12Z INDICATED THIS
STATUS DECK WAS MAINLY CONFINED TO THE 900MB TO 850MB LEVEL. BELOW
THIS STATUS DECK SURFACE TEMPERATURES AS OF 17Z WERE MAINLY IN THE
20S.

&&

.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 143 PM CST THU JAN 24 2013

12Z NAM AND 12Z GFS VERIFIED FAIRLY WELL AT 18Z WITH THE LOCATION
OF AN UPPER LEVEL TROUGH THAT WAS LOCATED OVER WESTERN
MONTANA/NORTHERN IDAHO EARLIER THIS MORNING. THE NAM AND GFS
REMAINED IN GOOD AGREEMENT MOVING THIS UPPER LEVEL TROUGH ACROSS
THE NORTHERN PLAINS DURING THE OVERNIGHT HOURS AND BY EARLY FRIDAY
MORNING PLACED THIS UPPER TROUGH OVER THE WESTERN GREAT LAKES
REGION. AS THIS SYSTEM CROSSES THE NORTHERN PLAINS OVERNIGHT, A
COLD FRONT WILL DROP SOUTH TOWARDS THE CENTRAL PLAINS. AS THIS
FRONT APPROACHES KANSAS EARLY TONIGHT...A WEDGE OF WARMER AIR IN
THE LOWER LEVELS THAT WAS LOCATED AHEAD OF THIS COLD FRONT OVER
EASTERN WYOMING/MONTANA AT 12Z THURSDAY WILL DROP SOUTHEAST INTO
WESTERN KANSAS. GIVEN THIS WARMER AIR SPREADING INTO THE AREA
OVERNIGHT ALONG WITH MOSTLY CLOUDY SKIES, IT STILL APPEARS THE
PREVIOUS FORECAST IS ON TRACK KEEPING THE DIURNAL CHANGE IN
TEMPERATURES BETWEEN EARLIER TODAY AND OVERNIGHT SMALL. BASED ON
EXPECTED HIGHS TODAY WILL FAVOR OVERNIGHT LOWS MAINLY IN THE LOW
TO MID 20S.

ON FRIDAY AN UPPER LEVEL RIDGE AXIS WILL BUILD ACROSS THE ROCKIES
AS THE UPPER LEVEL TROUGH CROSSES THE GREAT LAKES AND OHIO VALLEY.
850MB TEMPERATURES FRIDAY AFTERNOON ARE FORECAST TO RANGE FROM
+4C TO +6C. 925MB TEMPERATURES WILL AVERAGE BETWEEN +8 AND +12C.
USING THESE AS A GUIDE FOR HIGHS FRIDAY AFTERNOON IT WOULD APPEAR
TEMPERATURES SHOULD REBOUND BACK AT LEAST INTO THE LOWER 50S.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 330 AM CST THU JAN 24 2013

FRIDAY WILL START WITH THE UPPER LEVEL FLOW OVER KANSAS IN A SLIGHT
DOWNSLOPE PATTERN WITH NORTHWEST FLOW ALOFT. SKIES SHOULD START
OUT FRIDAY MORNING SUNNY, WITH LIGHT NORTH TO NORTHWEST SURFACE
WINDS. BY FRIDAY AFTERNOON, A FEW HIGH CIRRUS CLOUDS WILL STREAM
IN WITH SKIES BECOMING MOSTLY SUNNY, AND WINDS SHIFTING TO THE
SOUTH AT 10 MPH OR LESS. CLOUDS WILL CONTINUE TO INCREASE FRIDAY
NIGHT.  WINDS WILL REMAIN SOUTH AT AROUND 10 MPH, SO MINIMUM TEMPS
WILL BE MILD IN THE MID 20S TO LOWER 30S.  ON SATURDAY, AN UPPER
LEVEL WAVE WILL BE APPROACHING FROM THE SOUTHWEST.  PLENTY OF
MOISTURE IS STILL SITTING OVER TEXAS AND WILL STILL BE THERE SATURDAY.
THE DEEP, SOUTHWEST FLOW ALOFT WILL ADVECT SOME OF THAT MOISTURE
NORTH INTO KANSAS.  WHEN THAT UPPER WAVE APPROACHES LATE SATURDAY,
THE MOISTURE WILL BE IN PLACE.  THERE ARE SLIGHT CHANCES FOR RAIN
IN OUR EAST VERY LATE ON SATURDAY, BUT PRECIPITATION CHANCES WILL
INCREASE SATURDAY NIGHT AS THE UPPER LIFT MOVES IN. PRECIPITATION
CHANCES WILL BE AS HIGH AS 50 PERCENT IN OUR EAST AND SOUTHEAST,
BASICALLY EAST OF HIGHWAY 19. AS FOR PRECIPITATION, RAIN WILL
DOMINATE, AND RAINFALL AMOUNTS WILL BE ON THE LIGHT SIDE.  THE GFS
MODEL HAS THE MOST PRECIP, WITH 0.25 IN OUR EAST, BUT THE GEM AND
THE ECMWF MODELS BOTH PRODUCE LESS THAN A TENTH OF AN INCH OF RAINFALL
SATURDAY AND SUNDAY MORNING.  SUNDAY, PRECIP CHANCES WILL JUST BE
ACROSS OUR EXTREME EASTERN TIER OF COUNTIES, FROM ELLIS SOUTH TO
BARBER COUNTY.

AFTER THIS WAVE PASSES SUNDAY, THE UPPER PATTERN WILL TURN TO THE
SOUTHWEST, WITH A WARMING TREND.  BY TUESDAY, MAX TEMPS SHOULD BE
WELL INTO THE MID 50S NORTH OF I-70 TO THE MID 60S SOUTH ALONG THE
OKLAHOMA BORDER. A LARGE, BROAD SCALE UPPER TROUGH WILL BE MOVING
INTO THE PLAINS TUESDAY INTO WEDNESDAY, AND A LOW END SLIGHT
CHANCE FOR RAIN WILL EXIST OVER OUR NORTHERN MOST COUNTIES OF
ELLIS AND TREGO.  I AM NOT TOO CONFIDENT IN THESE PRECIPITATION
CHANCES TUESDAY AND WEDNESDAY, SO STAYED WITH LOW 15-16 PERCENT
CHANCES ONLY, FOR NOW.

FOR MOST OF THIS EXTENDED FORECAST, THE ECMWF MODEL WAS FAVORED.
THE GFS SEEMS TOO WET AND SLOWER WITH THE UPPER PROGRESSION OF
WAVES.  THE GEM CANADIAN MODEL ON THE OTHER HAND IS FASTER AND LESS
WET.  THUS, THE ECMWF IS A GOOD COMPROMISE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1139 AM CST THU JAN 24 2013

12Z BUFR SOUNDINGS SUGGESTING MVFR STATUS DECK WILL LINGER ACROSS
ALL THE TAF SITES THROUGH AT LEAST THE LATE AFTERNOON. HRRR WAS A
LITTLE MORE PESSIMISTIC KEEPING THE STATUS IN AT GCK UNTIL AROUND
00Z. AT THIS TIME GIVEN THE LATEST SATELLITE LOOP WHICH SUGGESTED
SOME MID-HIGH LEVEL MOISTURE WAS ALREADY BEGINNING TO SPREAD INTO
WESTERN KANSAS LATE THIS MORNING HAVE DECIDED TO FOLLOW THE SLOWER
EROSION OF THE MVFR CIGS. AS A RESULT EXPECT CIGS TO REMAIN AS IS
UNTIL 00Z FRIDAY AT GCK, 03Z AT DDC AND HYS. EASTERLY SURFACE
WINDS AT 10KTS OR LESS WILL GRADUALLY SHIFT TO THE SOUTH/SOUTHWEST
BY LATE DAY.


&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  23  53  27  53 /   0   0   0  10
GCK  23  53  28  54 /   0   0   0  10
EHA  28  54  32  57 /   0   0   0  10
LBL  25  54  29  56 /   0   0   0  10
HYS  21  52  26  48 /   0   0   0   0
P28  23  55  26  49 /   0   0   0   0

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...BURGERT
SHORT TERM...BURGERT
LONG TERM...BURKE
AVIATION...BURGERT







AREA FORECAST DISCUSSION

NWS DODGE CITY KS

 1224 PM CST THU JAN 24 2013

...UPDATED THIS AFTERNOON PERIOD TO LOWER MAX TEMPERATURES...

.SYNOPSIS...
ISSUED AT 1139 AM CST THU JAN 24 2013

AT 12Z THURSDAY A 500MB TROUGH WAS LOCATED ACROSS WESTERN
MONTANA/NORTHERN IDAHO. THIS UPPER LEVEL TROUGH WAS ASSOCIATED
WITH A +120KT 250MB JET. EAST OF THIS UPPER LEVEL SYSTEM AT THE
850MB LEVEL A WEDGE OF WARM AIR WAS EVIDENT FROM EASTERN MONTANA
SOUTHWARD INTO WYOMING. THE 850MB TEMPERATURE AT GLASGOW, MT AT
12Z THURSDAY WAS +6C. AT THE SURFACE A COLD FRONT EXTENDED FROM
EASTERN MONTANA SOUTHWARD ACROSS WYOMING AND EASTERN COLORADO INTO
THE PANHANDLE OF TEXAS. JUST NORTH OF THIS FRONT SOME WARM MOIST
AIR WAS BEING ADVECTED INTO SOUTHWEST KANSAS AND HAD RESULTED IN
WIDESPREAD STATUS. DODGE CITY SOUNDING AT 12Z INDICATED THIS
STATUS DECK WAS MAINLY CONFINED TO THE 900MB TO 850MB LEVEL. BELOW
THIS STATUS DECK SURFACE TEMPERATURES AS OF 17Z WERE MAINLY IN THE
20S.

&&

.UPDATE...
ISSUED AT 1211 PM CST THU JAN 24 2013

LOW STATUS DECK ACROSS WESTERN KANSAS HAS BEEN SLOW TO ERODE
EARLIER THIS MORNING. BASED ON 17Z VISIBLE SATELLITE LOOP SOME HIGHER
LEVEL CLOUDS NOW APPEAR TO BE SPREADING INTO WESTERN KANSAS OVER
THIS LINGERING LOW STATUS DECK. 12Z NAM BUFR SOUNDINGS DOES
SUGGEST CLEARING IN THE WEST AFTER 3 PM, HOWEVER THE 14Z AND 15Z
RAPID REFRESH MODEL APPEARS TO BE MORE SLOWER WITH THE EROSION OF
THESE LOW CLOUDS. GIVEN THE HIGHER LEVEL CLOUD COVER THAT WERE ALREADY
BEGINNING TO SPREAD ACROSS WESTERN KANSAS HAVE FAVOR THE RAPID
REFRESH MODEL IN KEEPING CLOUDS IN LONGER. AS A RESULT HAVE
LOWERED AFTERNOON TEMPERATURES ACROSS WESTERN KANSAS.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 347 AM CST THU JAN 24 2013

A SHORTWAVE TROUGH WAS MOVING SOUTHEAST INTO THE GREAT LAKES REGION
THIS MORNING AND COLD HIGH PRESSURE WAS PUSHING SOUTH IN ITS WAKE.
THE WESTERN EDGE OF THIS COLD AIR WAS MOVING INTO SOUTHWEST KANSAS
IN UPSLOPE FASHION FROM THE NORTHEAST.  MEANWHILE, THE NEXT
SHORTWAVE TROUGH WAS PROGRESSING ACROSS THE PACIFIC NORTHWEST EARLY
THIS MORNING. THIS SYSTEM WILL APPROACH THE NORTHERN HIGH PLAINS BY
THIS AFTERNOON AND RESULT IN SURFACE TROUGHING IN THE LEE OF THE
NORTHERN ROCKIES. IF THIS SYSTEM WAS FASTER, THE ASSOCIATED
PACIFIC COLD FRONT WOULD HAVE NO PROBLEM SCOURING THE SHALLOW COLD
AIR OUT OF WESTERN KANSAS. HOWEVER, IT APPEARS THAT THE COLD
FRONTAL PASSAGE WILL HOLD OFF UNTIL LATER TONIGHT. ALSO, THE LEE
TROUGH AND ASSOCIATED SOUTHERLY WINDS AHEAD OF THE SYSTEM ARE NOT
ADVERTISED TO BE STRONG ENOUGH TO SCOUR OUT THE COLD AIR. INSTEAD,
THE ISENTROPIC LIFT WITH THE DEVELOPING SOUTHERLIES WILL AID IN
LOW CLOUD DEVELOPMENT THIS MORNING AND A WEAK UPSLOPE COMPONENT
WILL PERSIST AT LOWER LEVELS THROUGH THE DAY. THE NAM SOUNDINGS
SHOW A SHALLOW LAYER OF SATURATION ABOVE 900MB AND THIS IS
REASONABLE BASED ON THE HIGHER OBSERVED SURFACE DEWPOINTS
CURRENTLY RESIDING ACROSS OKLAHOMA. ALSO, PLENTY OF HIGH LEVEL
CLOUD WAS PRESENT ACROSS KANSAS THIS MORNING AND SHOULD PERSIST
THROUGH THE DAY AND FURTHER LIMIT INSOLATION. THEREFORE,
TEMPERATURES FROM DODGE CITY EASTWARD WILL STAY AT OR BELOW
FREEZING. SOME COLD AIR EROSION IS EXPECTED IN FAR WESTERN KANSAS
WHERE TEMPERATURES COULD REACH INTO THE UPPER 30S AND 40S. THE
OFFICIAL FORECAST WILL BE A FEW DEGREES COLDER THAN THE NAM. FOR
SOME REASON THE RAP ERODES THE COLD AIR WITH HIGHS IN THE MID 40S
EVEN AS FAR EAST AS DODGE CITY.

BY TONIGHT, THE LOW LEVEL WINDS ARE EXPECTED TO VEER TO THE
SOUTHWEST AS THE AFOREMENTIONED PACIFIC COLD FRONT APPROACHES.
THUS THE LOW CLOUDS WILL RAPIDLY CLEAR OUT. TEMPERATURES WILL
INITIALLY FALL INTO THE 20S OVERNIGHT BUT THEN HOLD STEADY OR
EVEN RISE AFTER 3 AM AS VERTICAL MIXING INCREASES BEHIND THE
PACIFIC COLD FRONT.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 330 AM CST THU JAN 24 2013

FRIDAY WILL START WITH THE UPPER LEVEL FLOW OVER KANSAS IN A SLIGHT
DOWNSLOPE PATTERN WITH NORTHWEST FLOW ALOFT. SKIES SHOULD START
OUT FRIDAY MORNING SUNNY, WITH LIGHT NORTH TO NORTHWEST SURFACE
WINDS. BY FRIDAY AFTERNOON, A FEW HIGH CIRRUS CLOUDS WILL STREAM
IN WITH SKIES BECOMING MOSTLY SUNNY, AND WINDS SHIFTING TO THE
SOUTH AT 10 MPH OR LESS. CLOUDS WILL CONTINUE TO INCREASE FRIDAY
NIGHT.  WINDS WILL REMAIN SOUTH AT AROUND 10 MPH, SO MINIMUM TEMPS
WILL BE MILD IN THE MID 20S TO LOWER 30S.  ON SATURDAY, AN UPPER
LEVEL WAVE WILL BE APPROACHING FROM THE SOUTHWEST.  PLENTY OF
MOISTURE IS STILL SITTING OVER TEXAS AND WILL STILL BE THERE SATURDAY.
THE DEEP, SOUTHWEST FLOW ALOFT WILL ADVECT SOME OF THAT MOISTURE
NORTH INTO KANSAS.  WHEN THAT UPPER WAVE APPROACHES LATE SATURDAY,
THE MOISTURE WILL BE IN PLACE.  THERE ARE SLIGHT CHANCES FOR RAIN
IN OUR EAST VERY LATE ON SATURDAY, BUT PRECIPITATION CHANCES WILL
INCREASE SATURDAY NIGHT AS THE UPPER LIFT MOVES IN. PRECIPITATION
CHANCES WILL BE AS HIGH AS 50 PERCENT IN OUR EAST AND SOUTHEAST,
BASICALLY EAST OF HIGHWAY 19. AS FOR PRECIPITATION, RAIN WILL
DOMINATE, AND RAINFALL AMOUNTS WILL BE ON THE LIGHT SIDE.  THE GFS
MODEL HAS THE MOST PRECIP, WITH 0.25 IN OUR EAST, BUT THE GEM AND
THE ECMWF MODELS BOTH PRODUCE LESS THAN A TENTH OF AN INCH OF RAINFALL
SATURDAY AND SUNDAY MORNING.  SUNDAY, PRECIP CHANCES WILL JUST BE
ACROSS OUR EXTREME EASTERN TIER OF COUNTIES, FROM ELLIS SOUTH TO
BARBER COUNTY.

AFTER THIS WAVE PASSES SUNDAY, THE UPPER PATTERN WILL TURN TO THE
SOUTHWEST, WITH A WARMING TREND.  BY TUESDAY, MAX TEMPS SHOULD BE
WELL INTO THE MID 50S NORTH OF I-70 TO THE MID 60S SOUTH ALONG THE
OKLAHOMA BORDER. A LARGE, BROAD SCALE UPPER TROUGH WILL BE MOVING
INTO THE PLAINS TUESDAY INTO WEDNESDAY, AND A LOW END SLIGHT
CHANCE FOR RAIN WILL EXIST OVER OUR NORTHERN MOST COUNTIES OF
ELLIS AND TREGO.  I AM NOT TOO CONFIDENT IN THESE PRECIPITATION
CHANCES TUESDAY AND WEDNESDAY, SO STAYED WITH LOW 15-16 PERCENT
CHANCES ONLY, FOR NOW.

FOR MOST OF THIS EXTENDED FORECAST, THE ECMWF MODEL WAS FAVORED.
THE GFS SEEMS TOO WET AND SLOWER WITH THE UPPER PROGRESSION OF
WAVES.  THE GEM CANADIAN MODEL ON THE OTHER HAND IS FASTER AND LESS
WET.  THUS, THE ECMWF IS A GOOD COMPROMISE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1139 AM CST THU JAN 24 2013

12Z BUFR SOUNDINGS SUGGESTING MVFR STATUS DECK WILL LINGER ACROSS
ALL THE TAF SITES THROUGH AT LEAST THE LATE AFTERNOON. HRRR WAS A
LITTLE MORE PESSIMISTIC KEEPING THE STATUS IN AT GCK UNTIL AROUND
00Z. AT THIS TIME GIVEN THE LATEST SATELLITE LOOP WHICH SUGGESTED
SOME MID-HIGH LEVEL MOISTURE WAS ALREADY BEGINNING TO SPREAD INTO
WESTERN KANSAS LATE THIS MORNING HAVE DECIDED TO FOLLOW THE SLOWER
EROSION OF THE MVFR CIGS. AS A RESULT EXPECT CIGS TO REMAIN AS IS
UNTIL 00Z FRIDAY AT GCK, 03Z AT DDC AND HYS. EASTERLY SURFACE
WINDS AT 10KTS OR LESS WILL GRADUALLY SHIFT TO THE SOUTH/SOUTHWEST
BY LATE DAY.


&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  25  52  27  53 /   0   0   0  20
GCK  25  52  28  54 /   0   0   0  10
EHA  27  53  32  57 /   0   0   0  10
LBL  26  53  29  56 /   0   0   0  10
HYS  22  50  26  48 /   0   0   0  20
P28  27  53  26  49 /   0   0   0  20

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...BURGERT
SYNOPSIS...BURGERT
SHORT TERM...FINCH
LONG TERM...BURKE
AVIATION...BURGERT






AREA FORECAST DISCUSSION

NWS DODGE CITY KS

 1141 AM CST THU JAN 24 2013

...UPDATED SYNOPSIS AND AVIATION DISCUSSION...

.SYNOPSIS...
ISSUED AT 1139 AM CST THU JAN 24 2013

AT 12Z THURSDAY A 500MB TROUGH WAS LOCATED ACROSS WESTERN
MONTANA/NORTHERN IDAHO. THIS UPPER LEVEL TROUGH WAS ASSOCIATED
WITH A +120KT 250MB JET. EAST OF THIS UPPER LEVEL SYSTEM AT THE
850MB LEVEL A WEDGE OF WARM AIR WAS EVIDENT FROM EASTERN MONTANA
SOUTHWARD INTO WYOMING. THE 850MB TEMPERATURE AT GLASGOW, MT AT
12Z THURSDAY WAS +6C. AT THE SURFACE A COLD FRONT EXTENDED FROM
EASTERN MONTANA SOUTHWARD ACROSS WYOMING AND EASTERN COLORADO INTO
THE PANHANDLE OF TEXAS. JUST NORTH OF THIS FRONT SOME WARM MOIST
AIR WAS BEING ADVECTED INTO SOUTHWEST KANSAS AND HAD RESULTED IN
WIDESPREAD STATUS. DODGE CITY SOUNDING AT 12Z INDICATED THIS
STATUS DECK WAS MAINLY CONFINED TO THE 900MB TO 850MB LEVEL. BELOW
THIS STATUS DECK SURFACE TEMPERATURES AS OF 17Z WERE MAINLY IN THE
20S.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 347 AM CST THU JAN 24 2013

A SHORTWAVE TROUGH WAS MOVING SOUTHEAST INTO THE GREAT LAKES REGION
THIS MORNING AND COLD HIGH PRESSURE WAS PUSHING SOUTH IN ITS WAKE.
THE WESTERN EDGE OF THIS COLD AIR WAS MOVING INTO SOUTHWEST KANSAS
IN UPSLOPE FASHION FROM THE NORTHEAST.  MEANWHILE, THE NEXT
SHORTWAVE TROUGH WAS PROGRESSING ACROSS THE PACIFIC NORTHWEST EARLY
THIS MORNING. THIS SYSTEM WILL APPROACH THE NORTHERN HIGH PLAINS BY
THIS AFTERNOON AND RESULT IN SURFACE TROUGHING IN THE LEE OF THE
NORTHERN ROCKIES. IF THIS SYSTEM WAS FASTER, THE ASSOCIATED
PACIFIC COLD FRONT WOULD HAVE NO PROBLEM SCOURING THE SHALLOW COLD
AIR OUT OF WESTERN KANSAS. HOWEVER, IT APPEARS THAT THE COLD
FRONTAL PASSAGE WILL HOLD OFF UNTIL LATER TONIGHT. ALSO, THE LEE
TROUGH AND ASSOCIATED SOUTHERLY WINDS AHEAD OF THE SYSTEM ARE NOT
ADVERTISED TO BE STRONG ENOUGH TO SCOUR OUT THE COLD AIR. INSTEAD,
THE ISENTROPIC LIFT WITH THE DEVELOPING SOUTHERLIES WILL AID IN
LOW CLOUD DEVELOPMENT THIS MORNING AND A WEAK UPSLOPE COMPONENT
WILL PERSIST AT LOWER LEVELS THROUGH THE DAY. THE NAM SOUNDINGS
SHOW A SHALLOW LAYER OF SATURATION ABOVE 900MB AND THIS IS
REASONABLE BASED ON THE HIGHER OBSERVED SURFACE DEWPOINTS
CURRENTLY RESIDING ACROSS OKLAHOMA. ALSO, PLENTY OF HIGH LEVEL
CLOUD WAS PRESENT ACROSS KANSAS THIS MORNING AND SHOULD PERSIST
THROUGH THE DAY AND FURTHER LIMIT INSOLATION. THEREFORE,
TEMPERATURES FROM DODGE CITY EASTWARD WILL STAY AT OR BELOW
FREEZING. SOME COLD AIR EROSION IS EXPECTED IN FAR WESTERN KANSAS
WHERE TEMPERATURES COULD REACH INTO THE UPPER 30S AND 40S. THE
OFFICIAL FORECAST WILL BE A FEW DEGREES COLDER THAN THE NAM. FOR
SOME REASON THE RAP ERODES THE COLD AIR WITH HIGHS IN THE MID 40S
EVEN AS FAR EAST AS DODGE CITY.

BY TONIGHT, THE LOW LEVEL WINDS ARE EXPECTED TO VEER TO THE
SOUTHWEST AS THE AFOREMENTIONED PACIFIC COLD FRONT APPROACHES.
THUS THE LOW CLOUDS WILL RAPIDLY CLEAR OUT. TEMPERATURES WILL
INITIALLY FALL INTO THE 20S OVERNIGHT BUT THEN HOLD STEADY OR
EVEN RISE AFTER 3 AM AS VERTICAL MIXING INCREASES BEHIND THE
PACIFIC COLD FRONT.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 330 AM CST THU JAN 24 2013

FRIDAY WILL START WITH THE UPPER LEVEL FLOW OVER KANSAS IN A SLIGHT
DOWNSLOPE PATTERN WITH NORTHWEST FLOW ALOFT. SKIES SHOULD START
OUT FRIDAY MORNING SUNNY, WITH LIGHT NORTH TO NORTHWEST SURFACE
WINDS. BY FRIDAY AFTERNOON, A FEW HIGH CIRRUS CLOUDS WILL STREAM
IN WITH SKIES BECOMING MOSTLY SUNNY, AND WINDS SHIFTING TO THE
SOUTH AT 10 MPH OR LESS. CLOUDS WILL CONTINUE TO INCREASE FRIDAY
NIGHT.  WINDS WILL REMAIN SOUTH AT AROUND 10 MPH, SO MINIMUM TEMPS
WILL BE MILD IN THE MID 20S TO LOWER 30S.  ON SATURDAY, AN UPPER
LEVEL WAVE WILL BE APPROACHING FROM THE SOUTHWEST.  PLENTY OF
MOISTURE IS STILL SITTING OVER TEXAS AND WILL STILL BE THERE SATURDAY.
THE DEEP, SOUTHWEST FLOW ALOFT WILL ADVECT SOME OF THAT MOISTURE
NORTH INTO KANSAS.  WHEN THAT UPPER WAVE APPROACHES LATE SATURDAY,
THE MOISTURE WILL BE IN PLACE.  THERE ARE SLIGHT CHANCES FOR RAIN
IN OUR EAST VERY LATE ON SATURDAY, BUT PRECIPITATION CHANCES WILL
INCREASE SATURDAY NIGHT AS THE UPPER LIFT MOVES IN. PRECIPITATION
CHANCES WILL BE AS HIGH AS 50 PERCENT IN OUR EAST AND SOUTHEAST,
BASICALLY EAST OF HIGHWAY 19. AS FOR PRECIPITATION, RAIN WILL
DOMINATE, AND RAINFALL AMOUNTS WILL BE ON THE LIGHT SIDE.  THE GFS
MODEL HAS THE MOST PRECIP, WITH 0.25 IN OUR EAST, BUT THE GEM AND
THE ECMWF MODELS BOTH PRODUCE LESS THAN A TENTH OF AN INCH OF RAINFALL
SATURDAY AND SUNDAY MORNING.  SUNDAY, PRECIP CHANCES WILL JUST BE
ACROSS OUR EXTREME EASTERN TIER OF COUNTIES, FROM ELLIS SOUTH TO
BARBER COUNTY.

AFTER THIS WAVE PASSES SUNDAY, THE UPPER PATTERN WILL TURN TO THE
SOUTHWEST, WITH A WARMING TREND.  BY TUESDAY, MAX TEMPS SHOULD BE
WELL INTO THE MID 50S NORTH OF I-70 TO THE MID 60S SOUTH ALONG THE
OKLAHOMA BORDER. A LARGE, BROAD SCALE UPPER TROUGH WILL BE MOVING
INTO THE PLAINS TUESDAY INTO WEDNESDAY, AND A LOW END SLIGHT
CHANCE FOR RAIN WILL EXIST OVER OUR NORTHERN MOST COUNTIES OF
ELLIS AND TREGO.  I AM NOT TOO CONFIDENT IN THESE PRECIPITATION
CHANCES TUESDAY AND WEDNESDAY, SO STAYED WITH LOW 15-16 PERCENT
CHANCES ONLY, FOR NOW.

FOR MOST OF THIS EXTENDED FORECAST, THE ECMWF MODEL WAS FAVORED.
THE GFS SEEMS TOO WET AND SLOWER WITH THE UPPER PROGRESSION OF
WAVES.  THE GEM CANADIAN MODEL ON THE OTHER HAND IS FASTER AND LESS
WET.  THUS, THE ECMWF IS A GOOD COMPROMISE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1139 AM CST THU JAN 24 2013

12Z BUFR SOUNDINGS SUGGESTING MVFR STATUS DECK WILL LINGER ACROSS
ALL THE TAF SITES THROUGH AT LEAST THE LATE AFTERNOON. HRRR WAS A
LITTLE MORE PESSIMISTIC KEEPING THE STATUS IN AT GCK UNTIL AROUND
00Z. AT THIS TIME GIVEN THE LATEST SATELLITE LOOP WHICH SUGGESTED
SOME MID-HIGH LEVEL MOISTURE WAS ALREADY BEGINNING TO SPREAD INTO
WESTERN KANSAS LATE THIS MORNING HAVE DECIDED TO FOLLOW THE SLOWER
EROSION OF THE MVFR CIGS. AS A RESULT EXPECT CIGS TO REMAIN AS IS
UNTIL 00Z FRIDAY AT GCK, 03Z AT DDC AND HYS. EASTERLY SURFACE
WINDS AT 10KTS OR LESS WILL GRADUALLY SHIFT TO THE SOUTH/SOUTHWEST
BY LATE DAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  32  25  52  27 /   0   0   0   0
GCK  36  25  52  28 /   0   0   0   0
EHA  46  27  53  32 /   0   0   0   0
LBL  38  26  53  29 /   0   0   0   0
HYS  31  22  50  26 /   0   0   0   0
P28  31  27  53  26 /   0   0   0   0

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...BURGERT
SHORT TERM...FINCH
LONG TERM...BURKE
AVIATION...BURGERT






AREA FORECAST DISCUSSION

NWS DODGE CITY KS

 524 AM CST THU JAN 24 2013

...UPDATED FOR THE AVIATION DISCUSSION...

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 347 AM CST THU JAN 24 2013

A SHORTWAVE TROUGH WAS MOVING SOUTHEAST INTO THE GREAT LAKES REGION
THIS MORNING AND COLD HIGH PRESSURE WAS PUSHING SOUTH IN ITS WAKE.
THE WESTERN EDGE OF THIS COLD AIR WAS MOVING INTO SOUTHWEST KANSAS
IN UPSLOPE FASHION FROM THE NORTHEAST.  MEANWHILE, THE NEXT
SHORTWAVE TROUGH WAS PROGRESSING ACROSS THE PACIFIC NORTHWEST EARLY
THIS MORNING. THIS SYSTEM WILL APPROACH THE NORTHERN HIGH PLAINS BY
THIS AFTERNOON AND RESULT IN SURFACE TROUGHING IN THE LEE OF THE
NORTHERN ROCKIES. IF THIS SYSTEM WAS FASTER, THE ASSOCIATED
PACIFIC COLD FRONT WOULD HAVE NO PROBLEM SCOURING THE SHALLOW COLD
AIR OUT OF WESTERN KANSAS. HOWEVER, IT APPEARS THAT THE COLD
FRONTAL PASSAGE WILL HOLD OFF UNTIL LATER TONIGHT. ALSO, THE LEE
TROUGH AND ASSOCIATED SOUTHERLY WINDS AHEAD OF THE SYSTEM ARE NOT
ADVERTISED TO BE STRONG ENOUGH TO SCOUR OUT THE COLD AIR. INSTEAD,
THE ISENTROPIC LIFT WITH THE DEVELOPING SOUTHERLIES WILL AID IN
LOW CLOUD DEVELOPMENT THIS MORNING AND A WEAK UPSLOPE COMPONENT
WILL PERSIST AT LOWER LEVELS THROUGH THE DAY. THE NAM SOUNDINGS
SHOW A SHALLOW LAYER OF SATURATION ABOVE 900MB AND THIS IS
REASONABLE BASED ON THE HIGHER OBSERVED SURFACE DEWPOINTS
CURRENTLY RESIDING ACROSS OKLAHOMA. ALSO, PLENTY OF HIGH LEVEL
CLOUD WAS PRESENT ACROSS KANSAS THIS MORNING AND SHOULD PERSIST
THROUGH THE DAY AND FURTHER LIMIT INSOLATION. THEREFORE,
TEMPERATURES FROM DODGE CITY EASTWARD WILL STAY AT OR BELOW
FREEZING. SOME COLD AIR EROSION IS EXPECTED IN FAR WESTERN KANSAS
WHERE TEMPERATURES COULD REACH INTO THE UPPER 30S AND 40S. THE
OFFICIAL FORECAST WILL BE A FEW DEGREES COLDER THAN THE NAM. FOR
SOME REASON THE RAP ERODES THE COLD AIR WITH HIGHS IN THE MID 40S
EVEN AS FAR EAST AS DODGE CITY.

BY TONIGHT, THE LOW LEVEL WINDS ARE EXPECTED TO VEER TO THE
SOUTHWEST AS THE AFOREMENTIONED PACIFIC COLD FRONT APPROACHES.
THUS THE LOW CLOUDS WILL RAPIDLY CLEAR OUT. TEMPERATURES WILL
INITIALLY FALL INTO THE 20S OVERNIGHT BUT THEN HOLD STEADY OR
EVEN RISE AFTER 3 AM AS VERTICAL MIXING INCREASES BEHIND THE
PACIFIC COLD FRONT.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 330 AM CST THU JAN 24 2013

FRIDAY WILL START WITH THE UPPER LEVEL FLOW OVER KANSAS IN A SLIGHT
DOWNSLOPE PATTERN WITH NORTHWEST FLOW ALOFT. SKIES SHOULD START
OUT FRIDAY MORNING SUNNY, WITH LIGHT NORTH TO NORTHWEST SURFACE
WINDS. BY FRIDAY AFTERNOON, A FEW HIGH CIRRUS CLOUDS WILL STREAM
IN WITH SKIES BECOMING MOSTLY SUNNY, AND WINDS SHIFTING TO THE
SOUTH AT 10 MPH OR LESS. CLOUDS WILL CONTINUE TO INCREASE FRIDAY
NIGHT.  WINDS WILL REMAIN SOUTH AT AROUND 10 MPH, SO MINIMUM TEMPS
WILL BE MILD IN THE MID 20S TO LOWER 30S.  ON SATURDAY, AN UPPER
LEVEL WAVE WILL BE APPROACHING FROM THE SOUTHWEST.  PLENTY OF
MOISTURE IS STILL SITTING OVER TEXAS AND WILL STILL BE THERE SATURDAY.
THE DEEP, SOUTHWEST FLOW ALOFT WILL ADVECT SOME OF THAT MOISTURE
NORTH INTO KANSAS.  WHEN THAT UPPER WAVE APPROACHES LATE SATURDAY,
THE MOISTURE WILL BE IN PLACE.  THERE ARE SLIGHT CHANCES FOR RAIN
IN OUR EAST VERY LATE ON SATURDAY, BUT PRECIPITATION CHANCES WILL
INCREASE SATURDAY NIGHT AS THE UPPER LIFT MOVES IN. PRECIPITATION
CHANCES WILL BE AS HIGH AS 50 PERCENT IN OUR EAST AND SOUTHEAST,
BASICALLY EAST OF HIGHWAY 19. AS FOR PRECIPITATION, RAIN WILL
DOMINATE, AND RAINFALL AMOUNTS WILL BE ON THE LIGHT SIDE.  THE GFS
MODEL HAS THE MOST PRECIP, WITH 0.25 IN OUR EAST, BUT THE GEM AND
THE ECMWF MODELS BOTH PRODUCE LESS THAN A TENTH OF AN INCH OF RAINFALL
SATURDAY AND SUNDAY MORNING.  SUNDAY, PRECIP CHANCES WILL JUST BE
ACROSS OUR EXTREME EASTERN TIER OF COUNTIES, FROM ELLIS SOUTH TO
BARBER COUNTY.

AFTER THIS WAVE PASSES SUNDAY, THE UPPER PATTERN WILL TURN TO THE
SOUTHWEST, WITH A WARMING TREND.  BY TUESDAY, MAX TEMPS SHOULD BE
WELL INTO THE MID 50S NORTH OF I-70 TO THE MID 60S SOUTH ALONG THE
OKLAHOMA BORDER. A LARGE, BROAD SCALE UPPER TROUGH WILL BE MOVING
INTO THE PLAINS TUESDAY INTO WEDNESDAY, AND A LOW END SLIGHT
CHANCE FOR RAIN WILL EXIST OVER OUR NORTHERN MOST COUNTIES OF
ELLIS AND TREGO.  I AM NOT TOO CONFIDENT IN THESE PRECIPITATION
CHANCES TUESDAY AND WEDNESDAY, SO STAYED WITH LOW 15-16 PERCENT
CHANCES ONLY, FOR NOW.

FOR MOST OF THIS EXTENDED FORECAST, THE ECMWF MODEL WAS FAVORED.
THE GFS SEEMS TOO WET AND SLOWER WITH THE UPPER PROGRESSION OF
WAVES.  THE GEM CANADIAN MODEL ON THE OTHER HAND IS FASTER AND LESS
WET.  THUS, THE ECMWF IS A GOOD COMPROMISE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 513 AM CST THU JAN 24 2013

AS THE SURFACE FLOW CONTINUES FROM THE EAST AND UPSLOPE IN
NATURE, LOW STRATUS CLOUDS WILL CONTINUE TO DEVELOP AND SPREAD
FROM WEST TO EAST.  THIS WILL RESULT IN IFR CIGS AT GCK AND
POSSIBLY HYS, AND IN THE MVFR CATEGORY AT DDC.  LATER THIS
EVENING, THE CLOUDS SHOULD BREAK UP AND VFR CONDITIONS DEVELOP, AS
WINDS BECOME FROM THE SOUTH AT AROUND 10 MPH.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  32  25  52  27 /   0   0   0   0
GCK  37  25  52  28 /   0   0   0   0
EHA  47  27  53  32 /   0   0   0   0
LBL  38  26  53  29 /   0   0   0   0
HYS  32  22  50  26 /   0   0   0   0
P28  29  27  53  26 /   0   0   0   0

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...FINCH
LONG TERM...BURKE
AVIATION...BURKE






AREA FORECAST DISCUSSION

NWS DODGE CITY KS

 400 AM CST THU JAN 24 2013

...UPDATED FOR SHORT TERM DISCUSSION...


.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 347 AM CST THU JAN 24 2013

A SHORTWAVE TROUGH WAS MOVING SOUTHEAST INTO THE GREAT LAKES REGION
THIS MORNING AND COLD HIGH PRESSURE WAS PUSHING SOUTH IN ITS WAKE.
THE WESTERN EDGE OF THIS COLD AIR WAS MOVING INTO SOUTHWEST KANSAS
IN UPSLOPE FASHION FROM THE NORTHEAST.  MEANWHILE, THE NEXT
SHORTWAVE TROUGH WAS PROGRESSING ACROSS THE PACIFIC NORTHWEST EARLY
THIS MORNING. THIS SYSTEM WILL APPROACH THE NORTHERN HIGH PLAINS BY
THIS AFTERNOON AND RESULT IN SURFACE TROUGHING IN THE LEE OF THE
NORTHERN ROCKIES. IF THIS SYSTEM WAS FASTER, THE ASSOCIATED
PACIFIC COLD FRONT WOULD HAVE NO PROBLEM SCOURING THE SHALLOW COLD
AIR OUT OF WESTERN KANSAS. HOWEVER, IT APPEARS THAT THE COLD
FRONTAL PASSAGE WILL HOLD OFF UNTIL LATER TONIGHT. ALSO, THE LEE
TROUGH AND ASSOCIATED SOUTHERLY WINDS AHEAD OF THE SYSTEM ARE NOT
ADVERTISED TO BE STRONG ENOUGH TO SCOUR OUT THE COLD AIR. INSTEAD,
THE ISENTROPIC LIFT WITH THE DEVELOPING SOUTHERLIES WILL AID IN
LOW CLOUD DEVELOPMENT THIS MORNING AND A WEAK UPSLOPE COMPONENT
WILL PERSIST AT LOWER LEVELS THROUGH THE DAY. THE NAM SOUNDINGS
SHOW A SHALLOW LAYER OF SATURATION ABOVE 900MB AND THIS IS
REASONABLE BASED ON THE HIGHER OBSERVED SURFACE DEWPOINTS
CURRENTLY RESIDING ACROSS OKLAHOMA. ALSO, PLENTY OF HIGH LEVEL
CLOUD WAS PRESENT ACROSS KANSAS THIS MORNING AND SHOULD PERSIST
THROUGH THE DAY AND FURTHER LIMIT INSOLATION. THEREFORE,
TEMPERATURES FROM DODGE CITY EASTWARD WILL STAY AT OR BELOW
FREEZING. SOME COLD AIR EROSION IS EXPECTED IN FAR WESTERN KANSAS
WHERE TEMPERATURES COULD REACH INTO THE UPPER 30S AND 40S. THE
OFFICIAL FORECAST WILL BE A FEW DEGREES COLDER THAN THE NAM. FOR
SOME REASON THE RAP ERODES THE COLD AIR WITH HIGHS IN THE MID 40S
EVEN AS FAR EAST AS DODGE CITY.

BY TONIGHT, THE LOW LEVEL WINDS ARE EXPECTED TO VEER TO THE
SOUTHWEST AS THE AFOREMENTIONED PACIFIC COLD FRONT APPROACHES.
THUS THE LOW CLOUDS WILL RAPIDLY CLEAR OUT. TEMPERATURES WILL
INITIALLY FALL INTO THE 20S OVERNIGHT BUT THEN HOLD STEADY OR
EVEN RISE AFTER 3 AM AS VERTICAL MIXING INCREASES BEHIND THE
PACIFIC COLD FRONT.


.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 330 AM CST THU JAN 24 2013

FRIDAY WILL START WITH THE UPPER LEVEL FLOW OVER KANSAS IN A SLIGHT
DOWNSLOPE PATTERN WITH NORTHWEST FLOW ALOFT. SKIES SHOULD START
OUT FRIDAY MORNING SUNNY, WITH LIGHT NORTH TO NORTHWEST SURFACE
WINDS. BY FRIDAY AFTERNOON, A FEW HIGH CIRRUS CLOUDS WILL STREAM
IN WITH SKIES BECOMING MOSTLY SUNNY, AND WINDS SHIFTING TO THE
SOUTH AT 10 MPH OR LESS. CLOUDS WILL CONTINUE TO INCREASE FRIDAY
NIGHT.  WINDS WILL REMAIN SOUTH AT AROUND 10 MPH, SO MINIMUM TEMPS
WILL BE MILD IN THE MID 20S TO LOWER 30S.  ON SATURDAY, AN UPPER
LEVEL WAVE WILL BE APPROACHING FROM THE SOUTHWEST.  PLENTY OF
MOISTURE IS STILL SITTING OVER TEXAS AND WILL STILL BE THERE SATURDAY.
THE DEEP, SOUTHWEST FLOW ALOFT WILL ADVECT SOME OF THAT MOISTURE
NORTH INTO KANSAS.  WHEN THAT UPPER WAVE APPROACHES LATE SATURDAY,
THE MOISTURE WILL BE IN PLACE.  THERE ARE SLIGHT CHANCES FOR RAIN
IN OUR EAST VERY LATE ON SATURDAY, BUT PRECIPITATION CHANCES WILL
INCREASE SATURDAY NIGHT AS THE UPPER LIFT MOVES IN. PRECIPITATION
CHANCES WILL BE AS HIGH AS 50 PERCENT IN OUR EAST AND SOUTHEAST,
BASICALLY EAST OF HIGHWAY 19. AS FOR PRECIPITATION, RAIN WILL
DOMINATE, AND RAINFALL AMOUNTS WILL BE ON THE LIGHT SIDE.  THE GFS
MODEL HAS THE MOST PRECIP, WITH 0.25 IN OUR EAST, BUT THE GEM AND
THE ECMWF MODELS BOTH PRODUCE LESS THAN A TENTH OF AN INCH OF RAINFALL
SATURDAY AND SUNDAY MORNING.  SUNDAY, PRECIP CHANCES WILL JUST BE
ACROSS OUR EXTREME EASTERN TIER OF COUNTIES, FROM ELLIS SOUTH TO
BARBER COUNTY.

AFTER THIS WAVE PASSES SUNDAY, THE UPPER PATTERN WILL TURN TO THE
SOUTHWEST, WITH A WARMING TREND.  BY TUESDAY, MAX TEMPS SHOULD BE
WELL INTO THE MID 50S NORTH OF I-70 TO THE MID 60S SOUTH ALONG THE
OKLAHOMA BORDER. A LARGE, BROAD SCALE UPPER TROUGH WILL BE MOVING
INTO THE PLAINS TUESDAY INTO WEDNESDAY, AND A LOW END SLIGHT
CHANCE FOR RAIN WILL EXIST OVER OUR NORTHERN MOST COUNTIES OF
ELLIS AND TREGO.  I AM NOT TOO CONFIDENT IN THESE PRECIPITATION
CHANCES TUESDAY AND WEDNESDAY, SO STAYED WITH LOW 15-16 PERCENT
CHANCES ONLY, FOR NOW.

FOR MOST OF THIS EXTENDED FORECAST, THE ECMWF MODEL WAS FAVORED.
THE GFS SEEMS TOO WET AND SLOWER WITH THE UPPER PROGRESSION OF
WAVES.  THE GEM CANADIAN MODEL ON THE OTHER HAND IS FASTER AND LESS
WET.  THUS, THE ECMWF IS A GOOD COMPROMISE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1102 PM CST WED JAN 23 2013

LOW LEVEL EASTERLY UPSLOPE FLOW WILL RESULT IN A GRADUAL MOISTENING OF
THE LOWER LEVELS, LEADING TO MVFR CIG DEVELOPMENT BETWEEN 11 AND
14Z AT GCK/DDC/HYS. WINDS WILL SHIFT TO A SOUTHERLY DIRECTION
LATER IN THE AFTERNOON, RESULTING IN A LOSS OF UPSLOPE AND EROSION
OF THE CIGS.


&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  32  25  52  27 /   0   0   0   0
GCK  37  25  52  28 /   0   0   0   0
EHA  47  27  53  32 /   0   0   0   0
LBL  38  26  53  29 /   0   0   0   0
HYS  32  22  50  26 /   0   0   0   0
P28  29  27  53  26 /   0   0   0   0

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...FINCH
LONG TERM...BURKE
AVIATION...FINCH






AREA FORECAST DISCUSSION

NWS WAKEFIELD VA

 708 AM EST THU JAN 24 2013

.SYNOPSIS...
A CLIPPER SYSTEM MOVES ACROSS THE MID ATLANTIC REGION THIS MORNING.
HIGH PRESSURE BUILDS IN FROM THE NORTH THURSDAY AND SETTLES OVER THE
AREA THURSDAY NIGHT. ANOTHER LOW PRESSURE SYSTEM CROSSES THE REGION
FRIDAY AFTERNOON INTO FRIDAY EVENING...BEFORE HIGH PRESSURE RETURNS
FOR THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SNOW IS TAPERING OFF ACROSS THE REGION THIS MORNING. THE WINTER
WEATHER ADVISORY HAS BEEN CANCELLED FOR THE CENTRAL VA PIEDMONT
AND MIDDLE PENINSULA AS VERY LITTLE TO NO ADDITIONAL ACCUMULATION
IS EXPECTED. HOWEVER...SLICK SPOTS COULD CONTINUE ON OVERPASSES
AND SECONDARY ROADS FOR THE NEXT FEW HOURS. FARTHER EAST...THE
ADVISORY HAS BEEN MAINTAINED AS A FEW LIGHT BANDS OF SNOW CONTINUE
TO AFFECT THE EASTERN SHORE. ADDITIONAL ACCUMULATION SHOULD BE
LESS THAN ONE INCH.

PREVIOUS DISCUSSION...
A CLIPPER SYSTEM IS PRESENTLY AFFECTING THE AREA WITH
SNOW FALLING FROM THE CENTRAL VA PIEDMONT TO THE EASTERN SHORE.
THE HEAVIEST BAND PER 88D RADAR MOSAIC AS DEVELOPED ROUGHLY ALONG
A LINE FROM EZF-NUI-WAL WITH ADDITIONAL ENHANCEMENT OF ECHOES OVER
THE MIDDLE PENINSULA. 24/06Z RUC DATA INDICATES ROBUST
FRONTOGENETIC FORCING PERSISTING FROM THE NRN NECK/MIDDLE
PENINSULA TO THE EASTERN SHORE OVER THE NEXT FEW HOURS BEFORE
DECLINING WNW-ESE FROM ABOUT 12-14Z. GIVEN THIS THERE IS RATHER
HIGH CONFIDENCE OF 1-2IN OF SNOW ACCUMULATION WITH ISOLATED
AMOUNTS TO 3IN POSSIBLE IN THE HEAVIEST BAND. RUC DATA ALSO
SUGGEST THE BEST WAA BEGINS TO DIMINISH OVER THE PIEDMONT DURING
THE NEXT FEW HOURS...BUT GIVEN THE PERSISTENCE OF LIGHT SNOW OVER
THE PAST FEW HOURS SOME LOCATIONS COULD RECEIVE A TOTAL SNOW
ACCUMULATION OF 1 TO PERHAPS 2IN. A WINTER WEATHER ADVISORY HAS
BEEN ISSUED TO ACCOUNT FOR THIS. THE ENTIRE ADVISORY IS IN ONE
SEGMENT ENDING AT 15Z (10AM) FOR SIMPLICITY...BUT WESTERN AREAS
WILL LIKELY SEE AN IMPROVEMENT WELL BEFORE THEN.

A PORTION OF THE MAIN POLAR VORTEX DROPS SE ACROSS NY OVERNIGHT
TOWARD LONG ISLAND BY MIDDAY. THIS TRIGGERS THE CLIPPER TO
STRENGTHEN OFFSHORE DRIVING STRONG CAA ACROSS THE MID ATLANTIC THIS
MORNING. FORECAST SOUNDINGS INDICATE STEEP LOW-LEVEL LAPSE RATES
WITH LINGERING MOISTURE FROM ABOUT 950-750MB RESULTING IN SOME
LIMITED CONVECTIVE INSTABILITY. HENCE THERE IS A POTENTIAL FOR
SCATTERED OR PERHAPS A BROKEN LINE OF SNOW SHOWERS TRACKING N-S
THROUGH THE MORNING FROM EASTERN VA TO NE NC AS SUGGESTED BY
HIGH-RES MODEL DATA.

A RATHER QUICK CLEARING TREND IS EXPECTED FROM NW-SE BY AFTERNOON
ALTHOUGH CHILLY TEMPERATURES WILL CONTINUE. HIGHS SHOULD RANGE FROM
THE UPPER 20S/LOW 30S N...TO MID 30S S. A 15-20MPH N WIND WITH GUSTS
TO 25 MPH WILL PRODUCE WIND CHILL VALUES OF 15-20 THROUGH MUCH OF
THE DAY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
A 1035MB ARCTIC (IN ORIGIN) HIGH BUILDS INTO THE MID ATLANTIC
TONIGHT. MEANWHILE...ANOTHER CLIPPER DIVES SE ACROSS THE NORTHERN
PLAINS AND UPPER MIDWEST. HIGH THIN CIRRUS WILL LIKELY BEGIN TO
OVERSPREAD THE REGION LATE...BUT MOST OF THE NIGHT SHOULD REMAIN
CLEAR TO MOSTLY CLEAR. THIS WILL ALLOW TEMPERATURES TO DROP OFF VERY
QUICKLY EVENTUALLY PLUMMETING TO 10-15 ASIDE FROM 15-20 FOR EXTREME
SE COASTAL LOCATIONS. AREAS WITH SNOW COVER FROM THE CURRENT CLIPPER
COULD FALL TO 5-10...ESPECIALLY OVER THE EASTERN SHORE WHERE THE SKY
SHOULD REMAIN CLEAR FOR THE LONGEST DURATION.

HIGH PRESSURE REMAINS OVER THE REGION TO BEGIN THE DAY FRIDAY BEFORE
SHIFTING OFFSHORE DURING THE AFTERNOON AS THE NEXT CLIPPER
APPROACHES FROM THE WEST. THE INITIAL SHORTWAVE REMAINS WELL N OF
THE REGION...BUT SECONDARY SHORTWAVE ENERGY TRIGGERS A WEAK LOW
ALONG THE ARCTIC BOUNDARY...WHICH TRACKS ACROSS NC BEFORE MOVING OFF
THE COAST AND DEEPENING WELL OFFSHORE FRIDAY NIGHT. MOISTURE
INCREASES ALOFT THROUGHOUT THE MORNING. HOWEVER...THE LOWER LEVELS
WILL REMAIN VERY DRY AND FORECAST SOUNDING DO NOT INDICATE
SATURATION UNTIL 18-21Z FOR THE PIEDMONT...AND 21-00Z FOR I-95 EAST.
DRY AIR ALOFT THEN QUICKLY INTRUDES THROUGH THE EVENING AS THE LOW
DEEPENS OFFSHORE. GIVEN THIS...QPF AMOUNTS WILL BE LIGHT AND EVEN
0.25IN SEEMS DIFFICULT TO ACHIEVE.

THE BEST FRONTOGENETIC FORCING APPEARS TO SET-UP FROM S-CENTRAL/SE VA
TO THE EASTERN SHORE DURING A SHORT PERIOD FORM LATE FRIDAY
AFTERNOON INTO FRIDAY EVENING. P-TYPE SHOULD PRIMARILY BE SNOW.
HOWEVER...WITH SSW FLOW A MIX OR CHANGE TO IP IS LIKELY OVER EXTREME
SE VA AND NE NC. PORTIONS OF NE NC COULD EVEN HAVE THE PRECIP END AS
A PERIOD OF LIGHT FREEZING DRIZZLE. ANY ICE ACCUMULATION SHOULD BE
MINIMAL. AS FOR SNOW ACCUMULATION...A BAND OF 1-2IN IS EXPECTED FROM
INTERIOR NE NC ACROSS S-CENTRAL/SE VA...WHILE 2-3IN IS POSSIBLE OVER
THE EASTERN SHORE. ELSEWHERE...SNOW ACCUMULATION SHOULD BE AN INCH
OR LESS. HIGHS FRIDAY SHOULD RANGE FROM THE UPPER 20 NW...TO THE
MID/UPPER 30S SE (PRIOR TO PRECIP EVAPORATING INTO THE AMBIENT
AIRMASS).

DRY NW FLOW PREVAILS SATURDAY AS THE LOW STRENGTHENS WELL OFF THE
COAST AND SFC HIGH PRESSURE RETURNS. LOWS SHOULD RANGE FROM THE
UPPER TEENS NW...TO MID 20S SE...FOLLOWED BY HIGHS RANGING FROM THE
LOW/MID 30S N...TO AROUND 40 S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
GOING WITH A COMBINATION OF THE 12Z GFS AND 12Z ECMWF MODELS FOR THE
EXTENDED PERIOD. DRY AND COLD CONDITIONS EXPECTED INITIALLY SAT NGT
AND SUN...THEN MILDER...ABOVE NORMAL TEMPS FCST FOR TUE AND WED. HI
PRES WILL BLD INTO AND OVR THE AREA SAT NGT AND SUN...THEN SLIDE OFF
THE CST FOR MON INTO WED. THERE COULD BE ISLTD RAIN SHOWERS...ESPLY
ACRS EXTRM NW OR NRN CNTIES MON AFTN THRU TUE NEAR A WARM FRONT.
OTHRWISE...A BETTER CHC FOR RAIN SHOWERS WILL BE DURING WED...AS A
COLD FRONT PUSHES INTO THE REGION.

MIN TEMPS WILL RANGE FM THE UPR TEENS TO MID 20S SUN MORNG...IN THE
MID 20S TO NEAR 30 MON MORNG...IN THE MID 30S TO LWR 40S TUE
MORNG...AND IN THE 40S WED MORNG. MAX TEMPS WILL RANGE FM THE MID
30S TO LWR 40S SUN...IN THE 40S TO NEAR 50 MON...IN THE LWR 50S TO
LWR 60S TUE...AND MAINLY IN THE UPR 50S TO MID 60S WED.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
LGT SNOW WILL COME TO AN END AT RIC/SBY OVER NEXT COUPLE HRS. HELD
ONTO IFR CONDITIONS UNTIL 13Z AT RIC AND 14Z AT SBY...IMPROVING TO
MVFR FOR A COUPLE HRS BEFORE BCMG VFR FOR THE REMAINDER OF THE
DAY. CLIPPER SYSTM MOVES OFFSHORE TDY...WITH WINDS SHIFTING TO
THE N/NW BEHIND THE SYSTM. WINDS WILL BE GUSTY THRU MIDDAY AND
AFTN DUE TO A TIGHTENING PRESSURE GRADIENT AS THE SYSTM
STRENGTHENS OFFSHORE AND STRONG HI PRES BLDS IN FROM THE WEST.

ANOTHER LO PRES SYSTEM MAY BRING A PERIOD OF SNOW (MIXED PCPN FOR
ECG) TO THE AREA FRI AFTN/EVENG WITH BRIEF PERIODS OF IFR
POSSIBLE. DRY WX AND VFR CONDITIONS EXPECTED FOR SAT AND SUN.

&&

.MARINE...
ALL MARINE HEADLINES ARE NOW IN EFFECT WITH CONDITIONS EXPECTED
WITHIN 12 HR. AREA OF LO PRES CURRENTLY OVER THE AREA WILL PUSH
OFFSHORE THRU THE MRNG HRS...ALLOWING FOR WINDS TO BECOME N/NW OVER
ALL WATERS BY MID MRNG. STRONG SFC PRES RISES WEST OF THE AREA AND
CAA WILL LEAD TO GALE CONDITIONS OVER THE SOUND/MOUTH OF THE
BAY/COASTAL WATERS SOUTH OF PARRAMORE ISLAND...WITH STRONG SCA
CONDITIONS OVER ALL OTHER WATERS. GALE FORCE WINDS WILL LAST UNTIL
ERLY THIS EVENG WHEN CAA CEASES...WITH GALE HEADLINES LIKELY BEING
REPLACED BY A SCA. EXPECT 5-7 FT SEAS OVER COASTAL WATERS AND 3-5 FT
WAVES OVER THE BAY TDY.

STRONG HI PRES BLDS DIRECTLY OVER THE AREA LATE TNGT INTO FRI AS
MARINE CONDITIONS IMPROVE. WINDS BECOME SOUTHERLY ~10 KT FRI AFTN AS
THE HI MOVES OFFSHORE. AN AREA OF LO PRES WILL TRACK INTO THE AREA
LATE FRI...STRENGTHENING AS IT PUSHES OFFSHORE FRI NGT INTO SAT. SCA
CONDITIONS ARE EXPECTED BEHIND THIS SYSTM WITH GUSTS UP TO GALE
FORCE POSSIBLE...ESPECIALLY OVER COASTAL WATERS.

&&

.HYDROLOGY...
FLOOD WARNING REMAINS IN EFFECT FOR THE NOTTOWAY RIVER AT
SEBRELL. THE RIVER CONTINUES TO TREND DOWNWARD. SEE LATEST
FLSAKQ/FLWAKQ FOR DETAILS.

&&

.CLIMATE...
AT RICHMOND...YESTERDAY`S HIGH WAS ABOVE 32 F...NOW MAKING IT 732
CONSECUTIVE DAYS WITH A HIGH ABOVE 32 F (AND STILL COUNTING). THE
PREVIOUS LONGEST STREAK HAD BEEN 730 DAYS (12/27/1948 TO
12/26/1950). IT WILL BE CLOSE THURSDAY AS THE LATEST FORECAST IS
FOR HIGHS NEAR 32 F. NOTE: NORFOLK HAS SET NO RECORDS WITH REGARD
TO THESE CRITERIA.

WELL BELOW AVERAGE TEMPERATURES CONTINUE THURSDAY BUT STILL NOT
GOING TO CHALLENGE ANY RECORDS.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     MDZ021>025.
NC...NONE.
VA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     VAZ075>078-099-100.
MARINE...GALE WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ633-634-654-
     656-658.
     SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR ANZ630>632-650-
     652.
     SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
     ANZ635>638.

&&

$$
SYNOPSIS...AJZ
NEAR TERM...AJZ
SHORT TERM...AJZ
LONG TERM...TMG
AVIATION...MAS
MARINE...MAS
HYDROLOGY...
CLIMATE...






AREA FORECAST DISCUSSION

NWS WAKEFIELD VA

 648 AM EST THU JAN 24 2013

.SYNOPSIS...
A CLIPPER SYSTEM MOVES ACROSS THE MID ATLANTIC REGION THIS MORNING.
HIGH PRESSURE BUILDS IN FROM THE NORTH THURSDAY AND SETTLES OVER THE
AREA THURSDAY NIGHT. ANOTHER LOW PRESSURE SYSTEM CROSSES THE REGION
FRIDAY AFTERNOON INTO FRIDAY EVENING...BEFORE HIGH PRESSURE RETURNS
FOR THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A CLIPPER SYSTEM IS PRESENTLY AFFECTING THE AREA WITH SNOW FALLING
FROM THE CENTRAL VA PIEDMONT TO THE EASTERN SHORE. THE HEAVIEST BAND
PER 88D RADAR MOSAIC AS DEVELOPED ROUGHLY ALONG A LINE FROM
EZF-NUI-WAL WITH ADDITIONAL ENHANCEMENT OF ECHOES OVER THE MIDDLE
PENINSULA. 24/06Z RUC DATA INDICATES ROBUST FRONTOGENETIC FORCING
PERSISTING FROM THE NRN NECK/MIDDLE PENINSULA TO THE EASTERN SHORE
OVER THE NEXT FEW HOURS BEFORE DECLINING WNW-ESE FROM ABOUT 12-14Z.
GIVEN THIS THERE IS RATHER HIGH CONFIDENCE OF 1-2IN OF SNOW
ACCUMULATION WITH ISOLATED AMOUNTS TO 3IN POSSIBLE IN THE HEAVIEST
BAND. RUC DATA ALSO SUGGEST THE BEST WAA BEGINS TO DIMINISH OVER THE
PIEDMONT DURING THE NEXT FEW HOURS...BUT GIVEN THE PERSISTENCE OF
LIGHT SNOW OVER THE PAST FEW HOURS SOME LOCATIONS COULD RECEIVE A
TOTAL SNOW ACCUMULATION OF 1 TO PERHAPS 2IN. A WINTER WEATHER
ADVISORY HAS BEEN ISSUED TO ACCOUNT FOR THIS. THE ENTIRE ADVISORY IS
IN ONE SEGMENT ENDING AT 15Z (10AM) FOR SIMPLICITY...BUT WESTERN
AREAS WILL LIKELY SEE AN IMPROVEMENT WELL BEFORE THEN.

A PORTION OF THE MAIN POLAR VORTEX DROPS SE ACROSS NY OVERNIGHT
TOWARD LONG ISLAND BY MIDDAY. THIS TRIGGERS THE CLIPPER TO
STRENGTHEN OFFSHORE DRIVING STRONG CAA ACROSS THE MID ATLANTIC THIS
MORNING. FORECAST SOUNDINGS INDICATE STEEP LOW-LEVEL LAPSE RATES
WITH LINGERING MOISTURE FROM ABOUT 950-750MB RESULTING IN SOME
LIMITED CONVECTIVE INSTABILITY. HENCE THERE IS A POTENTIAL FOR
SCATTERED OR PERHAPS A BROKEN LINE OF SNOW SHOWERS TRACKING N-S
THROUGH THE MORNING FROM EASTERN VA TO NE NC AS SUGGESTED BY
HIGH-RES MODEL DATA.

A RATHER QUICK CLEARING TREND IS EXPECTED FROM NW-SE BY AFTERNOON
ALTHOUGH CHILLY TEMPERATURES WILL CONTINUE. HIGHS SHOULD RANGE FROM
THE UPPER 20S/LOW 30S N...TO MID 30S S. A 15-20MPH N WIND WITH GUSTS
TO 25 MPH WILL PRODUCE WIND CHILL VALUES OF 15-20 THROUGH MUCH OF
THE DAY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
A 1035MB ARCTIC (IN ORIGIN) HIGH BUILDS INTO THE MID ATLANTIC
TONIGHT. MEANWHILE...ANOTHER CLIPPER DIVES SE ACROSS THE NORTHERN
PLAINS AND UPPER MIDWEST. HIGH THIN CIRRUS WILL LIKELY BEGIN TO
OVERSPREAD THE REGION LATE...BUT MOST OF THE NIGHT SHOULD REMAIN
CLEAR TO MOSTLY CLEAR. THIS WILL ALLOW TEMPERATURES TO DROP OFF VERY
QUICKLY EVENTUALLY PLUMMETING TO 10-15 ASIDE FROM 15-20 FOR EXTREME
SE COASTAL LOCATIONS. AREAS WITH SNOW COVER FROM THE CURRENT CLIPPER
COULD FALL TO 5-10...ESPECIALLY OVER THE EASTERN SHORE WHERE THE SKY
SHOULD REMAIN CLEAR FOR THE LONGEST DURATION.

HIGH PRESSURE REMAINS OVER THE REGION TO BEGIN THE DAY FRIDAY BEFORE
SHIFTING OFFSHORE DURING THE AFTERNOON AS THE NEXT CLIPPER
APPROACHES FROM THE WEST. THE INITIAL SHORTWAVE REMAINS WELL N OF
THE REGION...BUT SECONDARY SHORTWAVE ENERGY TRIGGERS A WEAK LOW
ALONG THE ARCTIC BOUNDARY...WHICH TRACKS ACROSS NC BEFORE MOVING OFF
THE COAST AND DEEPENING WELL OFFSHORE FRIDAY NIGHT. MOISTURE
INCREASES ALOFT THROUGHOUT THE MORNING. HOWEVER...THE LOWER LEVELS
WILL REMAIN VERY DRY AND FORECAST SOUNDING DO NOT INDICATE
SATURATION UNTIL 18-21Z FOR THE PIEDMONT...AND 21-00Z FOR I-95 EAST.
DRY AIR ALOFT THEN QUICKLY INTRUDES THROUGH THE EVENING AS THE LOW
DEEPENS OFFSHORE. GIVEN THIS...QPF AMOUNTS WILL BE LIGHT AND EVEN
0.25IN SEEMS DIFFICULT TO ACHIEVE.

THE BEST FRONTOGENETIC FORCING APPEARS TO SET-UP FROM S-CENTRAL/SE VA
TO THE EASTERN SHORE DURING A SHORT PERIOD FORM LATE FRIDAY
AFTERNOON INTO FRIDAY EVENING. P-TYPE SHOULD PRIMARILY BE SNOW.
HOWEVER...WITH SSW FLOW A MIX OR CHANGE TO IP IS LIKELY OVER EXTREME
SE VA AND NE NC. PORTIONS OF NE NC COULD EVEN HAVE THE PRECIP END AS
A PERIOD OF LIGHT FREEZING DRIZZLE. ANY ICE ACCUMULATION SHOULD BE
MINIMAL. AS FOR SNOW ACCUMULATION...A BAND OF 1-2IN IS EXPECTED FROM
INTERIOR NE NC ACROSS S-CENTRAL/SE VA...WHILE 2-3IN IS POSSIBLE OVER
THE EASTERN SHORE. ELSEWHERE...SNOW ACCUMULATION SHOULD BE AN INCH
OR LESS. HIGHS FRIDAY SHOULD RANGE FROM THE UPPER 20 NW...TO THE
MID/UPPER 30S SE (PRIOR TO PRECIP EVAPORATING INTO THE AMBIENT
AIRMASS).

DRY NW FLOW PREVAILS SATURDAY AS THE LOW STRENGTHENS WELL OFF THE
COAST AND SFC HIGH PRESSURE RETURNS. LOWS SHOULD RANGE FROM THE
UPPER TEENS NW...TO MID 20S SE...FOLLOWED BY HIGHS RANGING FROM THE
LOW/MID 30S N...TO AROUND 40 S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
GOING WITH A COMBINATION OF THE 12Z GFS AND 12Z ECMWF MODELS FOR THE
EXTENDED PERIOD. DRY AND COLD CONDITIONS EXPECTED INITIALLY SAT NGT
AND SUN...THEN MILDER...ABOVE NORMAL TEMPS FCST FOR TUE AND WED. HI
PRES WILL BLD INTO AND OVR THE AREA SAT NGT AND SUN...THEN SLIDE OFF
THE CST FOR MON INTO WED. THERE COULD BE ISLTD RAIN SHOWERS...ESPLY
ACRS EXTRM NW OR NRN CNTIES MON AFTN THRU TUE NEAR A WARM FRONT.
OTHRWISE...A BETTER CHC FOR RAIN SHOWERS WILL BE DURING WED...AS A
COLD FRONT PUSHES INTO THE REGION.

MIN TEMPS WILL RANGE FM THE UPR TEENS TO MID 20S SUN MORNG...IN THE
MID 20S TO NEAR 30 MON MORNG...IN THE MID 30S TO LWR 40S TUE
MORNG...AND IN THE 40S WED MORNG. MAX TEMPS WILL RANGE FM THE MID
30S TO LWR 40S SUN...IN THE 40S TO NEAR 50 MON...IN THE LWR 50S TO
LWR 60S TUE...AND MAINLY IN THE UPR 50S TO MID 60S WED.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
LGT SNOW WILL COME TO AN END AT RIC/SBY OVER NEXT COUPLE HRS. HELD
ONTO IFR CONDITIONS UNTIL 13Z AT RIC AND 14Z AT SBY...IMPROVING TO
MVFR FOR A COUPLE HRS BEFORE BCMG VFR FOR THE REMAINDER OF THE
DAY. CLIPPER SYSTM MOVES OFFSHORE TDY...WITH WINDS SHIFTING TO
THE N/NW BEHIND THE SYSTM. WINDS WILL BE GUSTY THRU MIDDAY AND
AFTN DUE TO A TIGHTENING PRESSURE GRADIENT AS THE SYSTM
STRENGTHENS OFFSHORE AND STRONG HI PRES BLDS IN FROM THE WEST.

ANOTHER LO PRES SYSTEM MAY BRING A PERIOD OF SNOW (MIXED PCPN FOR
ECG) TO THE AREA FRI AFTN/EVENG WITH BRIEF PERIODS OF IFR
POSSIBLE. DRY WX AND VFR CONDITIONS EXPECTED FOR SAT AND SUN.

&&

.MARINE...
ALL MARINE HEADLINES ARE NOW IN EFFECT WITH CONDITIONS EXPECTED
WITHIN 12 HR. AREA OF LO PRES CURRENTLY OVER THE AREA WILL PUSH
OFFSHORE THRU THE MRNG HRS...ALLOWING FOR WINDS TO BECOME N/NW OVER
ALL WATERS BY MID MRNG. STRONG SFC PRES RISES WEST OF THE AREA AND
CAA WILL LEAD TO GALE CONDITIONS OVER THE SOUND/MOUTH OF THE
BAY/COASTAL WATERS SOUTH OF PARRAMORE ISLAND...WITH STRONG SCA
CONDITIONS OVER ALL OTHER WATERS. GALE FORCE WINDS WILL LAST UNTIL
ERLY THIS EVENG WHEN CAA CEASES...WITH GALE HEADLINES LIKELY BEING
REPLACED BY A SCA. EXPECT 5-7 FT SEAS OVER COASTAL WATERS AND 3-5 FT
WAVES OVER THE BAY TDY.

STRONG HI PRES BLDS DIRECTLY OVER THE AREA LATE TNGT INTO FRI AS
MARINE CONDITIONS IMPROVE. WINDS BECOME SOUTHERLY ~10 KT FRI AFTN AS
THE HI MOVES OFFSHORE. AN AREA OF LO PRES WILL TRACK INTO THE AREA
LATE FRI...STRENGTHENING AS IT PUSHES OFFSHORE FRI NGT INTO SAT. SCA
CONDITIONS ARE EXPECTED BEHIND THIS SYSTM WITH GUSTS UP TO GALE
FORCE POSSIBLE...ESPECIALLY OVER COASTAL WATERS.

&&

.HYDROLOGY...
FLOOD WARNING REMAINS IN EFFECT FOR THE NOTTOWAY RIVER AT
SEBRELL. THE RIVER CONTINUES TO TREND DOWNWARD. SEE LATEST
FLSAKQ/FLWAKQ FOR DETAILS.

&&

.CLIMATE...
AT RICHMOND...YESTERDAY`S HIGH WAS ABOVE 32 F...NOW MAKING IT 732
CONSECUTIVE DAYS WITH A HIGH ABOVE 32 F (AND STILL COUNTING). THE
PREVIOUS LONGEST STREAK HAD BEEN 730 DAYS (12/27/1948 TO
12/26/1950). IT WILL BE CLOSE THURSDAY AS THE LATEST FORECAST IS
FOR HIGHS NEAR 32 F. NOTE: NORFOLK HAS SET NO RECORDS WITH REGARD
TO THESE CRITERIA.

WELL BELOW AVERAGE TEMPERATURES CONTINUE THURSDAY BUT STILL NOT
GOING TO CHALLENGE ANY RECORDS.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     MDZ021>025.
NC...NONE.
VA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     VAZ049-063-064-072>078-083>086-099-100.
MARINE...GALE WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ633-634-654-
     656-658.
     SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR ANZ630>632-650-
     652.
     SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
     ANZ635>638.

&&

$$
SYNOPSIS...AJZ
NEAR TERM...AJZ
SHORT TERM...AJZ
LONG TERM...TMG
AVIATION...MAS
MARINE...MAS
HYDROLOGY...
CLIMATE...







AREA FORECAST DISCUSSION

NWS WAKEFIELD VA

 425 AM EST THU JAN 24 2013

.SYNOPSIS...
A CLIPPER SYSTEM MOVES ACROSS THE MID ATLANTIC REGION THIS MORNING.
HIGH PRESSURE BUILDS IN FROM THE NORTH THURSDAY AND SETTLES OVER THE
AREA THURSDAY NIGHT. ANOTHER LOW PRESSURE SYSTEM CROSSES THE REGION
FRIDAY AFTERNOON INTO FRIDAY EVENING...BEFORE HIGH PRESSURE RETURNS
FOR THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A CLIPPER SYSTEM IS PRESENTLY AFFECTING THE AREA WITH SNOW FALLING
FROM THE CENTRAL VA PIEDMONT TO THE EASTERN SHORE. THE HEAVIEST BAND
PER 88D RADAR MOSAIC AS DEVELOPED ROUGHLY ALONG A LINE FROM
EZF-NUI-WAL WITH ADDITIONAL ENHANCEMENT OF ECHOES OVER THE MIDDLE
PENINSULA. 24/06Z RUC DATA INDICATES ROBUST FRONTOGENETIC FORCING
PERSISTING FROM THE NRN NECK/MIDDLE PENINSULA TO THE EASTERN SHORE
OVER THE NEXT FEW HOURS BEFORE DECLINING WNW-ESE FROM ABOUT 12-14Z.
GIVEN THIS THERE IS RATHER HIGH CONFIDENCE OF 1-2IN OF SNOW
ACCUMULATION WITH ISOLATED AMOUNTS TO 3IN POSSIBLE IN THE HEAVIEST
BAND. RUC DATA ALSO SUGGEST THE BEST WAA BEGINS TO DIMINISH OVER THE
PIEDMONT DURING THE NEXT FEW HOURS...BUT GIVEN THE PERSISTENCE OF
LIGHT SNOW OVER THE PAST FEW HOURS SOME LOCATIONS COULD RECEIVE A
TOTAL SNOW ACCUMULATION OF 1 TO PERHAPS 2IN. A WINTER WEATHER
ADVISORY HAS BEEN ISSUED TO ACCOUNT FOR THIS. THE ENTIRE ADVISORY IS
IN ONE SEGMENT ENDING AT 15Z (10AM) FOR SIMPLICITY...BUT WESTERN
AREAS WILL LIKELY SEE AN IMPROVEMENT WELL BEFORE THEN.

A PORTION OF THE MAIN POLAR VORTEX DROPS SE ACROSS NY OVERNIGHT
TOWARD LONG ISLAND BY MIDDAY. THIS TRIGGERS THE CLIPPER TO
STRENGTHEN OFFSHORE DRIVING STRONG CAA ACROSS THE MID ATLANTIC THIS
MORNING. FORECAST SOUNDINGS INDICATE STEEP LOW-LEVEL LAPSE RATES
WITH LINGERING MOISTURE FROM ABOUT 950-750MB RESULTING IN SOME
LIMITED CONVECTIVE INSTABILITY. HENCE THERE IS A POTENTIAL FOR
SCATTERED OR PERHAPS A BROKEN LINE OF SNOW SHOWERS TRACKING N-S
THROUGH THE MORNING FROM EASTERN VA TO NE NC AS SUGGESTED BY
HIGH-RES MODEL DATA.

A RATHER QUICK CLEARING TREND IS EXPECTED FROM NW-SE BY AFTERNOON
ALTHOUGH CHILLY TEMPERATURES WILL CONTINUE. HIGHS SHOULD RANGE FROM
THE UPPER 20S/LOW 30S N...TO MID 30S S. A 15-20MPH N WIND WITH GUSTS
TO 25 MPH WILL PRODUCE WIND CHILL VALUES OF 15-20 THROUGH MUCH OF
THE DAY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
A 1035MB ARCTIC (IN ORIGIN) HIGH BUILDS INTO THE MID ATLANTIC
TONIGHT. MEANWHILE...ANOTHER CLIPPER DIVES SE ACROSS THE NORTHERN
PLAINS AND UPPER MIDWEST. HIGH THIN CIRRUS WILL LIKELY BEGIN TO
OVERSPREAD THE REGION LATE...BUT MOST OF THE NIGHT SHOULD REMAIN
CLEAR TO MOSTLY CLEAR. THIS WILL ALLOW TEMPERATURES TO DROP OFF VERY
QUICKLY EVENTUALLY PLUMMETING TO 10-15 ASIDE FROM 15-20 FOR EXTREME
SE COASTAL LOCATIONS. AREAS WITH SNOW COVER FROM THE CURRENT CLIPPER
COULD FALL TO 5-10...ESPECIALLY OVER THE EASTERN SHORE WHERE THE SKY
SHOULD REMAIN CLEAR FOR THE LONGEST DURATION.

HIGH PRESSURE REMAINS OVER THE REGION TO BEGIN THE DAY FRIDAY BEFORE
SHIFTING OFFSHORE DURING THE AFTERNOON AS THE NEXT CLIPPER
APPROACHES FROM THE WEST. THE INITIAL SHORTWAVE REMAINS WELL N OF
THE REGION...BUT SECONDARY SHORTWAVE ENERGY TRIGGERS A WEAK LOW
ALONG THE ARCTIC BOUNDARY...WHICH TRACKS ACROSS NC BEFORE MOVING OFF
THE COAST AND DEEPENING WELL OFFSHORE FRIDAY NIGHT. MOISTURE
INCREASES ALOFT THROUGHOUT THE MORNING. HOWEVER...THE LOWER LEVELS
WILL REMAIN VERY DRY AND FORECAST SOUNDING DO NOT INDICATE
SATURATION UNTIL 18-21Z FOR THE PIEDMONT...AND 21-00Z FOR I-95 EAST.
DRY AIR ALOFT THEN QUICKLY INTRUDES THROUGH THE EVENING AS THE LOW
DEEPENS OFFSHORE. GIVEN THIS...QPF AMOUNTS WILL BE LIGHT AND EVEN
0.25IN SEEMS DIFFICULT TO ACHIEVE.

THE BEST FRONTOGENETIC FORCING APPEARS TO SET-UP FROM S-CENTRAL/SE VA
TO THE EASTERN SHORE DURING A SHORT PERIOD FORM LATE FRIDAY
AFTERNOON INTO FRIDAY EVENING. P-TYPE SHOULD PRIMARILY BE SNOW.
HOWEVER...WITH SSW FLOW A MIX OR CHANGE TO IP IS LIKELY OVER EXTREME
SE VA AND NE NC. PORTIONS OF NE NC COULD EVEN HAVE THE PRECIP END AS
A PERIOD OF LIGHT FREEZING DRIZZLE. ANY ICE ACCUMULATION SHOULD BE
MINIMAL. AS FOR SNOW ACCUMULATION...A BAND OF 1-2IN IS EXPECTED FROM
INTERIOR NE NC ACROSS S-CENTRAL/SE VA...WHILE 2-3IN IS POSSIBLE OVER
THE EASTERN SHORE. ELSEWHERE...SNOW ACCUMULATION SHOULD BE AN INCH
OR LESS. HIGHS FRIDAY SHOULD RANGE FROM THE UPPER 20 NW...TO THE
MID/UPPER 30S SE (PRIOR TO PRECIP EVAPORATING INTO THE AMBIENT
AIRMASS).

DRY NW FLOW PREVAILS SATURDAY AS THE LOW STRENGTHENS WELL OFF THE
COAST AND SFC HIGH PRESSURE RETURNS. LOWS SHOULD RANGE FROM THE
UPPER TEENS NW...TO MID 20S SE...FOLLOWED BY HIGHS RANGING FROM THE
LOW/MID 30S N...TO AROUND 40 S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
GOING WITH A COMBINATION OF THE 12Z GFS AND 12Z ECMWF MODELS FOR THE
EXTENDED PERIOD. DRY AND COLD CONDITIONS EXPECTED INITIALLY SAT NGT
AND SUN...THEN MILDER...ABOVE NORMAL TEMPS FCST FOR TUE AND WED. HI
PRES WILL BLD INTO AND OVR THE AREA SAT NGT AND SUN...THEN SLIDE OFF
THE CST FOR MON INTO WED. THERE COULD BE ISLTD RAIN SHOWERS...ESPLY
ACRS EXTRM NW OR NRN CNTIES MON AFTN THRU TUE NEAR A WARM FRONT.
OTHRWISE...A BETTER CHC FOR RAIN SHOWERS WILL BE DURING WED...AS A
COLD FRONT PUSHES INTO THE REGION.

MIN TEMPS WILL RANGE FM THE UPR TEENS TO MID 20S SUN MORNG...IN THE
MID 20S TO NEAR 30 MON MORNG...IN THE MID 30S TO LWR 40S TUE
MORNG...AND IN THE 40S WED MORNG. MAX TEMPS WILL RANGE FM THE MID
30S TO LWR 40S SUN...IN THE 40S TO NEAR 50 MON...IN THE LWR 50S TO
LWR 60S TUE...AND MAINLY IN THE UPR 50S TO MID 60S WED.

&&

.AVIATION /09Z THURSDAY THROUGH MONDAY/...
SNOW SHOWERS ARE EXPECTED OVRNGT THRU EARLY THU
MORNG...ESPECIALLY AT RIC/SBY FM A CLIPPER SYSTEM MOVING THRU THE
AREA. VSBY/CIG REDUCTIONS (TO MVFR AT RIC AND IFR AT SBY) HAVE
BEEN ADDED...WITH MENTION OF -SN IN THE SBY/RIC TAFS UNTIL 12Z.
VFR CONDITIONS WILL PREVAIL AFTER 12Z THU AS WINDS SHIFT TO THE N
BEHIND THIS SYSTEM. WINDS WILL BE GUSTY THRU MUCH OF THE AFTN DUE
TO A TIGHTENING PRESSURE GRADIENT AS THE SYSTEM STRENGTHENS
OFFSHORE.

ANOTHER LO PRES SYSTEM MAY BRING A PERIOD OF SNOW (MIXED PCPN FOR
ECG) TO THE AREA FRI AFTN/EVENG WITH BRIEF PERIODS OF IFR
POSSIBLE. DRY WX AND VFR CONDITIONS EXPECTED FOR SAT AND SUN.

&&

.MARINE...
ALL MARINE HEADLINES ARE NOW IN EFFECT WITH CONDITIONS EXPECTED
WITHIN 12 HR. AREA OF LO PRES CURRENTLY OVER THE AREA WILL PUSH
OFFSHORE THRU THE MRNG HRS...ALLOWING FOR WINDS TO BECOME N/NW OVER
ALL WATERS BY MID MRNG. STRONG SFC PRES RISES WEST OF THE AREA AND
CAA WILL LEAD TO GALE CONDITIONS OVER THE SOUND/MOUTH OF THE
BAY/COASTAL WATERS SOUTH OF PARRAMORE ISLAND...WITH STRONG SCA
CONDITIONS OVER ALL OTHER WATERS. GALE FORCE WINDS WILL LAST UNTIL
ERLY THIS EVENG WHEN CAA CEASES...WITH GALE HEADLINES LIKELY BEING
REPLACED BY A SCA. EXPECT 5-7 FT SEAS OVER COASTAL WATERS AND 3-5 FT
WAVES OVER THE BAY TDY.

STRONG HI PRES BLDS DIRECTLY OVER THE AREA LATE TNGT INTO FRI AS
MARINE CONDITIONS IMPROVE. WINDS BECOME SOUTHERLY ~10 KT FRI AFTN AS
THE HI MOVES OFFSHORE. AN AREA OF LO PRES WILL TRACK INTO THE AREA
LATE FRI...STRENGTHENING AS IT PUSHES OFFSHORE FRI NGT INTO SAT. SCA
CONDITIONS ARE EXPECTED BEHIND THIS SYSTM WITH GUSTS UP TO GALE
FORCE POSSIBLE...ESPECIALLY OVER COASTAL WATERS.

&&

.HYDROLOGY...
FLOOD WARNINGS REMAIN IN EFFECT FOR THE BLACKWATER RIVER ABOVE
FRANKLIN AND THE NOTTOWAY RIVER AT SEBRELL. BOTH RIVERS CONTINUE
TO TREND DOWNWARD. SEE LATEST FLSAKQ/FLWAKQ FOR DETAILS.

&&

.CLIMATE...
AT RICHMOND...TODAY`S HIGH WAS ABOVE 32 F...NOW MAKING IT 732
CONSECUTIVE DAYS WITH A HIGH ABOVE 32 F (AND STILL COUNTING). THE
PREVIOUS LONGEST STREAK HAD BEEN 730 DAYS (12/27/1948 TO 12/26/1950).
IT WILL BE CLOSE THURSDAY AS THE LATEST FORECAST IS FOR HIGHS NEAR
32 F. NOTE: NORFOLK HAS SET NO RECORDS WITH REGARD TO THESE
CRITERIA.

WELL BELOW AVERAGE TEMPERATURES CONTINUE THURS BUT STILL NOT GOING TO
CHALLENGE ANY RECORDS.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     MDZ021>025.
NC...NONE.
VA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     VAZ049-063-064-072>078-083>086-099-100.
MARINE...GALE WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ633-634-654-
     656-658.
     SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR ANZ630>632-650-
     652.
     SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
     ANZ635>638.

&&

$$
SYNOPSIS...AJZ
NEAR TERM...AJZ
SHORT TERM...AJZ
LONG TERM...TMG
AVIATION...MAS
MARINE...MAS
HYDROLOGY...AKQ
CLIMATE...AKQ




AREA FORECAST DISCUSSION

NWS WAKEFIELD VA

 249 AM EST THU JAN 24 2013

.SYNOPSIS...
A CLIPPER SYSTEM MOVES ACROSS THE MID ATLANTIC REGION LATE
TONIGHT INTO THURSDAY MORNING. HIGH PRESSURE BUILDS IN FROM THE
NORTH THURSDAY AND SETTLES OVER THE AREA THURSDAY NIGHT. ANOTHER
LOW PRESSURE SYSTEM CROSSES THE REGION FRIDAY AFTERNOON INTO
FRIDAY EVENING...BEFORE HIGH PRESSURE RETURNS FOR THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A CLIPPER SYSTEM IS PRESENTLY AFFECTING THE AREA WITH SNOW FALLING
FROM THE CENTRAL VA PIEDMONT TO THE EASTERN SHORE. THE HEAVIEST BAND
PER 88D RADAR MOSAIC AS DEVELOPED ROUGHLY ALONG A LINE FROM
EZF-NUI-WAL WITH ADDITIONAL ENHANCEMENT OF ECHOES OVER THE MIDDLE
PENINSULA. 24/06Z RUC DATA INDICATES ROBUST FRONTOGENETIC FORCING
PERSISTING FROM THE NRN NECK/MIDDLE PENINSULA TO THE EASTERN SHORE
OVER THE NEXT FEW HOURS BEFORE DECLINING WNW-ESE FROM ABOUT 12-14Z.
GIVEN THIS THERE IS RATHER HIGH CONFIDENCE OF 1-2IN OF SNOW
ACCUMULATION WITH ISOLATED AMOUNTS TO 3IN POSSIBLE IN THE HEAVIEST
BAND. RUC DATA ALSO SUGGEST THE BEST WAA BEGINS TO DIMINISH OVER THE
PIEDMONT DURING THE NEXT FEW HOURS...BUT GIVEN THE PERSISTENCE OF
LIGHT SNOW OVER THE PAST FEW HOURS SOME LOCATIONS COULD RECEIVE A
TOTAL SNOW ACCUMULATION OF 1 TO PERHAPS 2IN. A WINTER WEATHER
ADVISORY HAS BEEN ISSUED TO ACCOUNT FOR THIS. THE ENTIRE ADVISORY IS
IN ONE SEGMENT ENDING AT 15Z (10AM) FOR SIMPLICITY...BUT WESTERN
AREAS WILL LIKELY SEE AN IMPROVEMENT WELL BEFORE THEN.

A PORTION OF THE MAIN POLAR VORTEX DROPS SE ACROSS NY OVERNIGHT
TOWARD LONG ISLAND BY MIDDAY. THIS TRIGGERS THE CLIPPER TO
STRENGTHEN OFFSHORE DRIVING STRONG CAA ACROSS THE MID ATLANTIC THIS
MORNING. FORECAST SOUNDINGS INDICATE STEEP LOW-LEVEL LAPSE RATES
WITH LINGERING MOISTURE FROM ABOUT 950-750MB RESULTING IN SOME
LIMITED CONVECTIVE INSTABILITY. HENCE THERE IS A POTENTIAL FOR
SCATTERED OR PERHAPS A BROKEN LINE OF SNOW SHOWERS TRACKING N-S
THROUGH THE MORNING FROM EASTERN VA TO NE NC AS SUGGESTED BY
HIGH-RES MODEL DATA.

A RATHER QUICK CLEARING TREND IS EXPECTED FROM NW-SE BY AFTERNOON
ALTHOUGH CHILLY TEMPERATURES WILL CONTINUE. HIGHS SHOULD RANGE FROM
THE UPPER 20S/LOW 30S N...TO MID 30S S. A 15-20MPH N WIND WITH GUSTS
TO 25 MPH WILL PRODUCE WIND CHILL VALUES OF 15-20 THROUGH MUCH OF
THE DAY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
CAA RESUMES THURSDAY AS HIGH PRESSURE BUILDS IN FROM THE N RE-
ENFORCING THE ARCTIC AIR. HIGH TEMPERATURES SHOULD RANGE FROM THE
UPPER 20S N...TO MID 30S S UNDER A PARTLY TO MOSTLY SUNNY SKY. A N
WIND OF 15-20 MPH...WITH GUSTS TO 25-30 MPH WILL PUSH WIND CHILL
VALUES INTO THE UPPER SINGLE DIGITS TO MID TEENS THURSDAY
MORNING...WHICH WILL ONLY IMPROVE TO THE MID TEENS TO LOW 20S BY
AFTERNOON.

A 1030-1035M AREA OF HIGH PRESSURE BUILDS INTO THE REGION THURSDAY
NIGHT THROUGH FRIDAY MORNING. CLEAR SKIES EARLY ON SHOULD ALLOW
LOW TEMPERATURES TO FALL INTO THE TEENS AND POTENTIALLY SINGLE
DIGITS OVER THE EASTERN SHORE.

HIGH PRESSURE WEAKENS AND SHIFTS OFFSHORE FRIDAY AFTERNOON AHEAD OF
A DISORGANIZED AREA OF LOW PRESSURE APPROACHING FROM THE
WEST...WHICH WEAKENS FRIDAY AFTERNOON AND THEN REDEVELOPS OFF THE
COAST FRIDAY NIGHT. THIS REMAINS A LOW CONFIDENCE FORECAST AT THIS
TIME...BUT PRESENTLY THERE IS LITTLE MODEL DATA THAT SUPPORTS THIS
BEING A SUBSTANTIAL WINTER STORM. ALL AREAS SHOULD BE COLD ENOUGH
FOR SNOW...WITH THE POSSIBLE EXCEPTION OF THE FAR SE (NE NC) WHERE
SOME RAIN MAY MIX IN. OUTSIDE OF MAYBE COASTAL NE NC...P-TYPE
SHOULD BE ALL SNOW WITH MOST DATA INDICATING ONLY A MINOR
ACCUMULATION (COATING TO 2 INCHES) AT THIS TIME. SIMILAR TO
TONIGHT...A DRY AIRMASS WILL BE IN PLACE SO INITIAL PRECIPITATION
WILL EVAPORATE TO MOISTEN THE AIRMASS. IF MODELS CONTINUE ON
CURRENT TRENDS...THEN THE BEST CHANCE FOR 1-2" OF SNOW WILL BE
ACROSS SE VA AND NE NC (SOUTHEAST OF METRO RIC). DRY NW FLOW
PREVAILS LATE FRIDAY NIGHT INTO SATURDAY AS THE LOW STRENGTHENS
WELL OFF THE COAST AND SFC HIGH PRESSURE RETURNS. LOWS SHOULD
RANGE FROM THE UPPER TEENS NW...TO UPPER 20S SE. HIGHS SATURDAY IN
THE 30S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
GOING WITH A COMBINATION OF THE 12Z GFS AND 12Z ECMWF MODELS FOR THE
EXTENDED PERIOD. DRY AND COLD CONDITIONS EXPECTED INITIALLY SAT NGT
AND SUN...THEN MILDER...ABOVE NORMAL TEMPS FCST FOR TUE AND WED. HI
PRES WILL BLD INTO AND OVR THE AREA SAT NGT AND SUN...THEN SLIDE OFF
THE CST FOR MON INTO WED. THERE COULD BE ISLTD RAIN SHOWERS...ESPLY
ACRS EXTRM NW OR NRN CNTIES MON AFTN THRU TUE NEAR A WARM FRONT.
OTHRWISE...A BETTER CHC FOR RAIN SHOWERS WILL BE DURING WED...AS A
COLD FRONT PUSHES INTO THE REGION.

MIN TEMPS WILL RANGE FM THE UPR TEENS TO MID 20S SUN MORNG...IN THE
MID 20S TO NEAR 30 MON MORNG...IN THE MID 30S TO LWR 40S TUE
MORNG...AND IN THE 40S WED MORNG. MAX TEMPS WILL RANGE FM THE MID
30S TO LWR 40S SUN...IN THE 40S TO NEAR 50 MON...IN THE LWR 50S TO
LWR 60S TUE...AND MAINLY IN THE UPR 50S TO MID 60S WED.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
SNOW SHOWERS ARE EXPECTED OVRNGT THRU EARLY THU
MORNG...ESPECIALLY AT RIC/SBY FM A CLIPPER SYSTEM MOVING THRU THE
AREA. VSBY/CIG REDUCTIONS (TO MVFR AT RIC AND IFR AT SBY) HAVE
BEEN ADDED...WITH MENTION OF -SN IN THE SBY/RIC TAFS UNTIL 12Z.
VFR CONDITIONS WILL PREVAIL AFTER 12Z THU AS WINDS SHIFT TO THE N
BEHIND THIS SYSTEM. WINDS WILL BE GUSTY THRU MUCH OF THE AFTN DUE
TO A TIGHTENING PRESSURE GRADIENT AS THE SYSTEM STRENGTHENS
OFFSHORE.

ANOTHER LO PRES SYSTEM MAY BRING A PERIOD OF SNOW (MIXED PCPN FOR
ECG) TO THE AREA FRI AFTN/EVENG WITH BRIEF PERIODS OF IFR
POSSIBLE. DRY WX AND VFR CONDITIONS EXPECTED FOR SAT AND SUN.

&&

.MARINE...
CALM CONDITIONS THIS EVENING AND OVERNIGHT WILL GIVE WAY TO ROUGH
CONDITIONS BY EARLY THURSDAY MORNING. A CLIPPER SYSTEM WILL SWING
ACROSS THE WATERS FROM NW TO SE BEFORE MOVING OFF THE MID ATLANTIC
COAST THURSDAY MORNING. WINDS WILL SHIFT TO A W OR NW DIRECTION IN
THE VICINITY OF THE COLD FRONT...THEN BECOME NW-N BEHIND IT AS THE
PRESSURE GRADIENT TIGHTENS AND STRONG CAA COMMENCES. GENERALLY
WINDS WILL BE 15-20 KT ALL WATERS DURING THE PRE-DAWN HOURS...WHICH
WILL THEN INCREASE RAPIDLY BY MID MORNING. CLOSEST TO THE DEPARTING
LOW PRESSURE SYSTEM...GALE FORCE WIND GUSTS OF 35-40 KT WILL OCCUR
FROM MID MORNING THROUGH THE AFTERNOON OVER THE FOLLOWING AREAS:
COASTAL WATERS FROM PARRAMORE ISLAND TO CURRITUCK LIGHT...CURRITUCK
SOUND...AND THE MOUTH OF CHES BAY. GALE CONDITIONS ARE EXPECTED TO
DIMINISH INTO SOLID SCA SPEEDS BY EARLY THU EVENING. GALE WARNINGS
HAVE BEEN ISSUED FOR THESE AREAS...WITH THE MAIN IMPACT OCCURRING
THURSDAY MID MORNING THROUGH THE AFTERNOON. SEAS WILL BUILD TO
4-7 FT AND WAVES IN THE BAY WILL BE 4-5 FT DURING THIS TIMEFRAME.

STRONG SCA CONDITIONS WILL DEVELOP AROUND DAYBREAK OVER THE REST
OF CHES BAY...ERN VA RIVERS AND NRN COAST WATERS FROM FENWICK
ISLAND TO PARRAMORE ISLAND AND SCA FLAGS CONTINUE FOR THESE AREAS.
N WINDS GENERALLY 20-25 KT WITH GUSTS TO AROUND 30 KT WILL REMAIN
ELEVATED THROUGH THE AFTERNOON BEFORE TAPERING OFF THROUGH THE
EVENING. SEAS WILL BUILD TO 4-6 FT AND WAVES TO 4 FT DURING THIS
TIME.

HIGH PRESSURE THEN BUILDS INTO THE AREA THURSDAY NIGHT AND NW-N
WINDS WILL BECOME LIGHT (AOB 15 KT) THROUGH FRIDAY. HIGH PRESSURE
WILL SHIFT EAST AND PUSH OFFSHORE FRIDAY AFTERNOON AND SOUTHERLY
FLOW WILL DEVELOP. A LOW PRESSURE SYSTEM OVER THE GREAT LAKES THEN
TRACKS INTO THE MID ATLANTIC REGION FRIDAY NIGHT. ONCE IT MOVES
OFFSHORE...IT WILL DEEPEN AND RESULT IN YET ANOTHER CAA SURGE LATE
FRIDAY NIGHT INTO SATURDAY. GALE FORCE GUSTS MAY BE POSSIBLE ON
SATURDAY.

&&

.HYDROLOGY...
FLOOD WARNINGS REMAIN IN EFFECT FOR THE BLACKWATER RIVER ABOVE
FRANKLIN AND THE NOTTOWAY RIVER AT SEBRELL. BOTH RIVERS CONTINUE
TO TREND DOWNWARD. SEE LATEST FLSAKQ/FLWAKQ FOR DETAILS.

&&

.CLIMATE...
AT RICHMOND...TODAY`S HIGH WAS ABOVE 32 F...NOW MAKING IT 732
CONSECUTIVE DAYS WITH A HIGH ABOVE 32 F (AND STILL COUNTING). THE
PREVIOUS LONGEST STREAK HAD BEEN 730 DAYS (12/27/1948 TO 12/26/1950).
IT WILL BE CLOSE THURSDAY AS THE LATEST FORECAST IS FOR HIGHS NEAR
32 F. NOTE: NORFOLK HAS SET NO RECORDS WITH REGARD TO THESE
CRITERIA.

WELL BELOW AVERAGE TEMPERATURES CONTINUE THURS BUT STILL NOT GOING TO
CHALLENGE ANY RECORDS.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     MDZ021>025.
NC...NONE.
VA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     VAZ049-063-064-072>078-083>086-099-100.
MARINE...GALE WARNING UNTIL 6 PM EST THIS EVENING FOR ANZ634-654-656-
     658.
     SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 1 AM EST FRIDAY
     FOR ANZ650-652.
     SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
     ANZ635>638.
     SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR ANZ630>632.
     GALE WARNING UNTIL 6 PM EST THIS EVENING FOR ANZ633.

&&

$$
SYNOPSIS...ALB/JDM
NEAR TERM...AJZ
SHORT TERM...AJZ/JDM
LONG TERM...TMG
AVIATION...MAS/TMG/DAP
MARINE...BMD
HYDROLOGY...AKQ
CLIMATE...AKQ




AREA FORECAST DISCUSSION

NWS ST LOUIS MO

 340 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 SCENARION 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 INSUE 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 INBETWEEN 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 QUANDRY 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 THROUGHT
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 VELOW 700 HPA LEADING TO
STRONG EVAPORATIONAL COOLING/WETBULBING. 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 INOCUOUS 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 1127 AM CST THU JAN 24 2013

A SURFACE HIGH CURRENTLY CENTERED IN THE UPPER MS VALLEY WILL MOVE
EAST THROUGH THE OH VALLEY OVER THE NEXT 24 HOURS RESULTING IN
WINDS VEERING FROM EASTERLY THIS AFTERNOON TO SOUTHEASTERLY
TONIGHT. THROUGH MUCH OF THE EVENING...VFR CONDITIONS ARE EXPECTED
TO PREVAIL. MEANWHILE A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE
LOWER MS VALLEY TONIGHT ALLOWING WARM AND MOIST AIR WILL RIDE UP
AND OVER THE COLD AIR AT THE SURFACE....BRINGING THE POTENTIAL OF
A LIGHT WINTRY MIX ACROSS EASTERN MISSOURI AND ILLINOIS LATE
TONIGHT AND CIGS LOWERING TO MVFR. THERE STILL REMAINS MUCH
UNCERTAINTY ON THE LIKELYHOOD OF ANY PRECIPITATION BUT IF IT
OCCURS...AMOUNTS SHOULD BE QUITE LIGHT. I HAVE KEPT THE PROB30
GROUPS FROM 09-12Z TO ACCOUNT FOR THE PROBABILITY OF
PRECIPITATION. CIGS SHOULD IMPROVE FROM WEST TO EAST ON FRIDAY
MORNING INTO THE EARLY AFTERNOON AS A NEW COLD FRONT BRINGS A
WESTERLY WIND SHIFT.

SPECIFICS FOR KSTL...

VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE EVENING AS
WINDS GRADUALLY VEER FROM EASTERLY THIS AFTERNOON TO SOUTHEAST
THIS EVENING. A STORM SYSTEM TO THE SOUTH COULD PRODUCE A LIGHT WINTRY
MIX BETWEEN 09-12Z WITH CIGS LOWERING TO MVFR. THERE STILL REMAINS
MUCH UNCERTAINTY ON THE LIKELYHOOD OF ANY PRECIPITATION BUT IF IT
OCCURS...AMOUNTS SHOULD BE QUITE LIGHT AND THE MOST LIKELY PTYPES
ARE SLEET AND FREEZING DRIZZLE. CIGS SHOULD LIFT BY EARLY AFTERNOON
AS A NEW COLD FRONT BRINGS A WESTERLY WIND SHIFT.

GLASS

&&

.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 OMAHA/VALLEY NE

 515 PM CST FRI JAN 25 2013

.AVIATION...00Z TAFS FOR KOFK...KLNK AND KOMA.

VFR CONDITIONS ARE EXPECTED THROUGH SATURDAY AFTERNOON. A WEAK
COLD FRONT WILL BRUSH EASTERN NEBRASKA SWITCHING WINDS TO THE
NORTHEAST OVERNIGHT...BUT SPEED WILL BE UNDER 10KT. INCREASING
SOUTHERLY WINDS ON SATURDAY SHOULD AVERAGE 10 TO 15KT WITH ONLY
SCATTERED TO BROKEN MID AND HIGH CLOUDS EXPECTED.

DERGAN

&&

.PREV DISCUSSION... /ISSUED 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

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

$$



AREA FORECAST DISCUSSION

NWS HASTINGS NE

 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.

&&

.PREV DISCUSSION... /ISSUED 1134 AM CST THU JAN 24 2013/

AVIATION...PREVAILING VFR CONDITIONS ARE EXPECTED AT KGRI FOR AT
LEAST THE NEXT 24 HOURS. PLENTY OF HIGH CLOUD COVER IS EXPECTED
ACROSS THE TERMINAL THROUGH THE PERIOD...WITH A BRIEF PERIOD OF
MVFR CIGS THIS AFTERNOON...WITH THE PRIMARY FOCUS BEING ON WIND
DIRECTION AND SPEED. EXPECT THE AREA OF SURFACE HIGH PRESSURE
ACROSS MINNESOTA THIS MORNING TO SLIP SOUTH THROUGH THE AFTERNOON
HORUS...AS A WARM FRONT APPROACHES FROM THE WEST. THIS SHOULD ACT
TO TIGHTEN THE LOCAL PRESSURE GRADIENT...WITH WINDS INCREASING AND
SHIFTING FROM THE SOUTHEAST TO SOUTHWEST BY AFTERNOON. AFTER THE
PASSAGE OF THIS WARM FRONT...EXPECT WINDS TO SHIFT AND BECOME
NORTHWESTERLY DURING THE OVERNIGHT HOURS...WITH 30 TO 35KTS OF
LLWS POSSIBLE AROUND THE PASSAGE OF THIS BOUNDARY. KEPT MENTION OF
LLWS OUT OF TAF FOR TIME BEING...BUT MAY NEED TO CONSIDER FOR 00Z
TAF.

&&

.GID WATCHES/WARNINGS/ADVISORIES...

NE...NONE.
KS...NONE.

&&

$$








AREA FORECAST DISCUSSION

NWS RALEIGH NC

 555 AM EST THU JAN 24 2013

.SYNOPSIS...
AN ARCTIC COLD FRONT WILL USHER STRONG HIGH PRESSURE INTO THE
CAROLINAS TODAY. A COMPLEX LOW PRESSURE SYSTEM WILL TRACK EAST
ACROSS THE REGION ON FRIDAY.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 325 AM THURSDAY...

TODAY:
A POTENT UPPER LEVEL TROUGH OVER THE LOWER GREAT LAKES AT 06Z WILL
DIG SOUTHEAST OFFSHORE THE MID-ATLANTIC COAST BETWEEN 12-18Z TODAY.
AN ATTENDANT CLIPPER LOW WILL TRACK RAPIDLY EAST THROUGH NC/VA
BETWEEN 06-12Z...PROGRESSING OFFSHORE AFTER SUNRISE. PRONOUNCED
SUBSIDENCE IN THE WAKE OF THE UPPER LEVEL TROUGH WILL RESULT IN
STRONG PRESSURE RISES OVER THE OH VALLEY AND MID-ATLANTIC THIS
MORNING...DRIVING AN ARCTIC COLD FRONT RAPIDLY SOUTHWARD THROUGH
CENTRAL NC BETWEEN 12-15Z. PRESSURE RISES AS GREAT AS 5-7 MB IN 3-HR
ARE PROGGED OVER CENTRAL NC IN THE WAKE OF THE FRONT BETWEEN ROUGHLY
14-17Z...AND THE 06Z RAP INDICATES LOW-LEVEL FLOW BETWEEN 30-40 KT
AT THE BEGINNING OF THAT TIME-FRAME (STRONGEST SE COASTAL PLAIN)
WHEN THE MIXED LAYER WILL BE RAPIDLY DEEPENING IN ASSOC/W THE ONSET
OF STRONG COLD ADVECTION. EXPECT STRONG NORTHERLY WINDS FOR A FEW
HOURS IN THE IMMEDIATE WAKE OF THE FRONT...WITH PEAK SUSTAINED WINDS
AS HIGH AS 20-30 MPH AND GUSTS AS HIGH AS 35-40 MPH FOR A BRIEF
PERIOD...ESPECIALLY ACROSS PORTIONS OF THE SANDHILLS (CUMBERLAND)
AND SE COASTAL PLAIN (WAYNE/SAMPSON). GIVEN A STRONG FRONTAL PASSAGE
BY MID MORNING...WITH 1000-850 THICKNESSES PLUMMETING TO 1255-1265
METERS AND H85 TEMPS DECREASING TO -12 TO -15C BY MID AFTERNOON...
EXPECT THAT TEMPS WILL STRUGGLE TO RISE AT ALL DURING THE DAY. WILL
INDICATE HIGHS RANGING FROM THE LOWER 30S NORTH TO MID/UPPER 30S
SOUTH.

THE BEST FORCING ASSOC/W THE UPPER LEVEL WAVE WILL REMAIN NORTH OF
CENTRAL NC THIS MORNING...OVER SOUTHEAST VA AND THE DELMARVA. H85
FRONTOGENESIS WILL STRENGTHEN OVER THE NORTHERN PIEDMONT BETWEEN
09-12Z...CONTRIBUTING TO OVERCAST CLOUD COVER WITH CEILINGS
3500-5000 FT AGL NORTH OF HWY 64. HOWEVER...THE ONSET OF LOW-LEVEL
COLD ADVECTION WILL HELP TO `CANCEL OUT` FORCING ASSOC/W
FRONTOGENESIS...AND A RELATIVELY DRY BOUNDARY LAYER WILL PROVIDE A
FURTHER BARRIER FOR ANY LIGHT PRECIPITATION TO MAKE IT TO THE
GROUND. INTERESTINGLY...H85 COLD ADVECTION WILL BE SO STRONG THAT
TEMPS AT THAT LEVEL WILL FALL WITHIN THE ICE NUCLEATION ZONE (-12 TO
-15C) NORTH OF HWY 64 THIS AFTERNOON...AND FCST SOUNDINGS SHOW A
POTENTIAL FOR VERY SHALLOW DESTABILIZATION BETWEEN 17-21Z IN THE NE
COASTAL PLAIN WHERE NORTHERLY FLOW WILL ADVECT LOW-LEVEL MOISTURE
SOUTHWARD FROM THE MID-ATLANTIC COAST INTO EASTERN PORTIONS OF NC.
AS A RESULT...IT IS POSSIBLE THAT ISOLD SNOW SHOWERS COULD DEVELOP
OVER NORTHEASTERN NC THIS AFTERNOON. WITH THIS IN MIND...WILL
INDICATE A SLIGHT CHANCE OF SHOWER SHOWERS OVER WARREN/HALIFAX AND
EDGECOMBE COUNTIES BETWEEN 17-21Z...CONSISTENT WITH SIMULATED
REFLECTIVITY OUTPUT FROM THE 00Z HIGH RES WRF-NMM.

TONIGHT:
EXPECT CLEAR SKIES OVERNIGHT AS ARCTIC HIGH PRESSURE BUILDS DIRECTLY
OVER CENTRAL NC.  LOWS WILL BE DRIVEN BY A COMBINATION OF COLD
ADVECTION (EARLY ON) AND RADIATIONAL COOLING. WILL INDICATE LOWS
RANGING FROM THE MID/UPPER TEENS TO LOWER 20S. -VINCENT

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
AS OF 240 AM THURSDAY...

...A LIGHT WINTRY MIX STILL POSSIBLE FRIDAY AND FRIDAY EVENING...

THE TREND OF THE MODELS CONTINUES TO BE TOWARD A FLATTER MID/UPPER
WAVE SOLUTION AND VERY LIGHT QPF... FOR FRIDAY AND FRIDAY EVENING AS
THE SYSTEM MOVES THROUGH THE TENNESSEE AND LOWER OHIO VALLEY REGION
ACROSS THE APPALACHIANS TO THE MID-ATLANTIC COAST. VERY COLD ARCTIC
AIR WILL BE IN PLACE. HOWEVER... MOISTURE WILL BE LACKING FOR A
SIGNIFICANT WINTER STORM. YET... WITH SUCH COLD AIR IN PLACE FRIDAY
BEFORE THE LIGHT PRECIPITATION EVENT UNFOLDS... THIS COULD TURN OUT
TO BE A MINIMAL PRECIPITATION / BUT HIGH IMPACT EVENT (I.E. THE
19JAN2005 LIGHT SNOW / HIGH IMPACT EVENT)... WHEN RDU MEASURED 1
INCH OF SNOW WITH 0.04 LIQUID EQUIVALENT / WITH TEMPERATURES IN THE
MID 20S DURING THE AFTERNOON.

THE LATEST MODELS CONTINUE TO INDICATE LOW QPF IN THE RANGE OF 0.1
TO 0.2 OF AN INCH... WITH MOST ENSEMBLE MEMBERS IN THE 0.05 TO 0.15
RANGE. THE MAJORITY OF THE PRECIPITATION TIMING IS FORECAST TO BE IN
THE LATE MORNING OR EARLY AFTERNOON BEGIN TIME... EXCEPT DURING THE
AFTERNOON IN THE SOUTHEAST... ENDING QUICKLY BY LATE AFTERNOON OR
VERY EARLY EVENING.

ALTHOUGH THE MODEL 1000/850 AND 850/700 THICKNESS FORECASTS CONTINUE
TO SHOW DECENT SPREAD... THE FAVORED 00Z/EC CONTINUES TO INDICATE
THE PREDOMINATE P-TYPE TO BE LIGHT SNOW NW (1280/1535M THICKNESSES)
...LIGHT SNOW WITH SLEET IN THE I-64 CORRIDOR (PARTIALS IN THE 1280S
AND 1540S - ENDING WITH 1300 AND 1550 OR SO). SURFACE WET BULB
FORECASTS KEEP TEMPERATURES IN THE 20S ALL DAY FROM RALEIGH WEST AND
NORTH THROUGH THE PIEDMONT INTO THE BLUE RIDGE. THIS WILL BE THE
AREA WHERE MEASURABLE SNOW AND SLEET IS FAVORED... WITH A
CHANGE-OVER TO LIGHT FREEZING RAIN OR FREEZING DRIZZLE BY SUNSET OR
SO (AS WE LOSE SATURATION IN THE ICE NUCLEATION ZONE ALOFT).
SNOWFALL ACCUMULATIONS OF AROUND AN INCH APPEAR POSSIBLE. THIS IS
WHERE A WINTER WEATHER ADVISORY WILL LIKELY BE NEEDED FRIDAY INTO
FRIDAY EVENING IN LATER FORECASTS (ASSUMING THE MODELS DO NOT
COMPLETELY DRY UP).

IN THE CORRIDOR FROM THE FAR SOUTHERN PIEDMONT... NORTHERN SANDHILLS
AND MUCH OF THE CENTRAL COASTAL PLAIN... MAINLY TO THE NORTH OF A
LINE FROM LAURINBURG TO FAYETTEVILLE TO GOLDSBORO / SOUTH OF 1-64
SHOULD BEGIN WITH LIGHT SNOW/SLEET WITH A CHANGE-OVER TO LIGHT
FREEZING RAIN WITH TRACE SNOW/SLEET (PREDOMINATE P-TYPES). SURFACE
WET BULBS HERE ARE FORECAST TO REACH NEAR 32... PLACING THIS REGION
IN LIKELY ADVISORY CRITERIA AS WELL.

TO THE EAST AND SOUTH OF LAURINBURG TO FAYETTEVILLE TO GOLDSBORO...
A COLD LIGHT RAIN MIXED WITH SLEET IS EXPECTED WITH WET BULBS 33-34
OR SO DURING THE AFTERNOON.

BOTTOM LINE... DUE TO THE EXPECTED LIGHT NATURE OF THE PRECIPITATION
EPISODE AND THE VERY COLD AIR IN PLACE FRIDAY INTO FRIDAY EVENING...
THIS COULD VERY WELL TURN OUT TO BE A LOW PRECIPITATION... YET
RATHER HIGH IMPACT EVENT. MODEL TRENDS CONTINUE TO DAMPEN THE WAVE
AND LESSEN THE QPF WITH TIME... WHICH MAKES THIS ONLY A LOW TO
MODERATE CONFIDENCE FORECAST FOR AMOUNTS. P-TYPE AND COLD AIR ARE
HIGH CONFIDENCE... QPF IS LOW CONFIDENCE.

CLOUDY AND COLD FRIDAY WITH LIGHT SNOW LIKELY NW... LIGHT SNOW/SLEET
CENTRAL... AND MOSTLY LIGHT RAIN SE LATE MORNING THROUGH THE
AFTERNOON.  HIGHS 28 TO 35.

FRIDAY NIGHT... PATCHY FREEZING RAIN/FREEZING DRIZZLE POSSIBLE
EARLY... THEN CLEARING LATE. COLD WITH POTENTIAL BLACK ICE. LOWS IN
THE 20S.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 200 AM THURSDAY...

SATURDAY AND SUNDAY:

ANOTHER MODIFIED ARCTIC AIR MASS DRIVEN BY A 1035+ SURFACE HIGH WILL
DIVE SE ACROSS OUR REGION. THE COLDEST NIGHT WILL LIKELY BE SATURDAY
NIGHT... ALTHOUGH SUNDAY NIGHT WILL BE NEARLY AS COLD... BUT WITH
LIGHTER WINDS. EXPECT MOSTLY CLEAR SKIES WITH LOWS IN THE 15-20
RANGE. HIGHS IN THE MID 30S TO MID 40S NW TO SE.

A STOUT WARMING TREND WILL BEGIN MONDAY... THEN BE FELT IN FULL
FORCE BY TUE-WED. THE ARCTIC  HIGH SHIFTS QUICKLY OFFSHORE MONDAY...
FOLLOWED BY A MODERATING SW FLOW. HIGHS SHOULD SHOOT UP QUICKLY INTO
THE MID 50S TO LOWER 60S MONDAY... AND REACH THE 60S TUE-WED. MUCH
MILDER NIGHTS ARE EXPECTED AS WELL WITH LOWS IN THE MID 30S TO LOWER
40S BY TUE AND IN THE 40S WEDNESDAY.

THE NEXT CHANCE OF RAIN APPEARS TO BE WEDNESDAY AS A COLD FRONT
APPROACHES FROM THE WEST.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 600 AM THURSDAY...

24-HR TAF PERIOD:
VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. A POSSIBLE
EXCEPTION WILL BE THE RWI TERMINAL WHERE A BRIEF PERIOD OF MVFR
CEILINGS WILL BE POSSIBLE BETWEEN 17-21Z. THE BIGGEST AVIATION
CONCERN WILL BE STRONG NORTHERLY WINDS FOR SEVERAL HOURS IN THE WAKE
OF A COLD FRONTAL PASSAGE EXPECTED TO OCCUR BETWEEN 12-15Z THIS
MORNING...EARLIEST AT THE INT/GSO TERMINALS AND LATEST AT THE FAY
TERMINAL. GIVEN STRONG PRESSURE RISES AND 30-40 KT FLOW IN A RAPIDLY
DEEPENING MIXED LAYER BEHIND THE FRONT...EXPECT PEAK SUSTAINED WINDS
OUT OF THE N/NNW AT 15-25 KT WITH GUSTS AS HIGH AS 30-35 KT IN THE
IMMEDIATE 2-3 HOURS (BETWEEN 15-18Z) POST FROPA. WINDS WILL
GRADUALLY WEAKEN TO 10-15 KT BY 21Z THIS AFTERNOON...BECOMING CALM
BY 00Z.

LOOKING AHEAD:
DETERIORATING CONDITIONS ARE EXPECTED DURING THE DAY FRIDAY IN
ASSOCIATION WITH A WEAK LOW PRESSURE SYSTEM MOVING EAST ACROSS THE
REGION. EXPECT THAT CEILINGS WILL LOWER INTO THE MVFR CATEGORY
EVERYWHERE BETWEEN 15-21Z FRI (EARLIEST INT/GSO AND LATEST
FAY/RWI)...WITH LIGHT PRECIP AND POTENTIALLY IFR/LIFR CONDITIONS
ASSOCIATED WITH A COLD AIR DAMMING WEDGE DURING THE LATE AFTERNOON
AND EVENING. A WINTRY MIX IS EXPECTED AT THE INT/GSO/RDU/RWI
TERMINALS...AND IFR/LIFR CONDITIONS ASSOCIATED WITH THE CAD WEDGE
WOULD BE UNLIKELY TO IMPROVE UNTIL SATURDAY WHEN ARCTIC HIGH
PRESSURE BUILDS INTO THE CAROLINAS. -VINCENT

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT






AREA FORECAST DISCUSSION

NWS RALEIGH NC

 336 AM EST THU JAN 24 2013

.SYNOPSIS...
AN ARCTIC COLD FRONT WILL USHER STRONG HIGH PRESSURE INTO THE
CAROLINAS TODAY AND TONIGHT. A COMPLEX LOW PRESSURE SYSTEM WILL
TRACK EAST ACROSS THE REGION ON FRIDAY.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 325 AM THURSDAY...

TODAY:
A POTENT UPPER LEVEL TROUGH OVER THE LOWER GREAT LAKES AT 06Z WILL
DIG SOUTHEAST OFFSHORE THE MID-ATLANTIC COAST BETWEEN 12-18Z TODAY.
AN ATTENDANT CLIPPER LOW WILL TRACK RAPIDLY EAST THROUGH NC/VA
BETWEEN 06-12Z...PROGRESSING OFFSHORE AFTER SUNRISE. PRONOUNCED
SUBSIDENCE IN THE WAKE OF THE UPPER LEVEL TROUGH WILL RESULT IN
STRONG PRESSURE RISES OVER THE OH VALLEY AND MID-ATLANTIC THIS
MORNING...DRIVING AN ARCTIC COLD FRONT RAPIDLY SOUTHWARD THROUGH
CENTRAL NC BETWEEN 12-15Z. PRESSURE RISES AS GREAT AS 5-7 MB IN 3-HR
ARE PROGGED OVER CENTRAL NC IN THE WAKE OF THE FRONT BETWEEN ROUGHLY
14-17Z...AND THE 06Z RAP INDICATES LOW-LEVEL FLOW BETWEEN 30-40 KT
AT THE BEGINNING OF THAT TIME-FRAME (STRONGEST SE COASTAL PLAIN)
WHEN THE MIXED LAYER WILL BE RAPIDLY DEEPENING IN ASSOC/W THE ONSET
OF STRONG COLD ADVECTION. EXPECT STRONG NORTHERLY WINDS FOR A FEW
HOURS IN THE IMMEDIATE WAKE OF THE FRONT...WITH PEAK SUSTAINED WINDS
AS HIGH AS 20-30 MPH AND GUSTS AS HIGH AS 35-40 MPH FOR A BRIEF
PERIOD...ESPECIALLY ACROSS PORTIONS OF THE SANDHILLS (CUMBERLAND)
AND SE COASTAL PLAIN (WAYNE/SAMPSON). GIVEN A STRONG FRONTAL PASSAGE
BY MID MORNING...WITH 1000-850 THICKNESSES PLUMMETING TO 1255-1265
METERS AND H85 TEMPS DECREASING TO -12 TO -15C BY MID AFTERNOON...
EXPECT THAT TEMPS WILL STRUGGLE TO RISE AT ALL DURING THE DAY. WILL
INDICATE HIGHS RANGING FROM THE LOWER 30S NORTH TO MID/UPPER 30S
SOUTH.

THE BEST FORCING ASSOC/W THE UPPER LEVEL WAVE WILL REMAIN NORTH OF
CENTRAL NC THIS MORNING...OVER SOUTHEAST VA AND THE DELMARVA. H85
FRONTOGENESIS WILL STRENGTHEN OVER THE NORTHERN PIEDMONT BETWEEN
09-12Z...CONTRIBUTING TO OVERCAST CLOUD COVER WITH CEILINGS
3500-5000 FT AGL NORTH OF HWY 64. HOWEVER...THE ONSET OF LOW-LEVEL
COLD ADVECTION WILL HELP TO `CANCEL OUT` FORCING ASSOC/W
FRONTOGENESIS...AND A RELATIVELY DRY BOUNDARY LAYER WILL PROVIDE A
FURTHER BARRIER FOR ANY LIGHT PRECIPITATION TO MAKE IT TO THE
GROUND. INTERESTINGLY...H85 COLD ADVECTION WILL BE SO STRONG THAT
TEMPS AT THAT LEVEL WILL FALL WITHIN THE ICE NUCLEATION ZONE (-12 TO
-15C) NORTH OF HWY 64 THIS AFTERNOON...AND FCST SOUNDINGS SHOW A
POTENTIAL FOR VERY SHALLOW DESTABILIZATION BETWEEN 17-21Z IN THE NE
COASTAL PLAIN WHERE NORTHERLY FLOW WILL ADVECT LOW-LEVEL MOISTURE
SOUTHWARD FROM THE MID-ATLANTIC COAST INTO EASTERN PORTIONS OF NC.
AS A RESULT...IT IS POSSIBLE THAT ISOLD SNOW SHOWERS COULD DEVELOP
OVER NORTHEASTERN NC THIS AFTERNOON. WITH THIS IN MIND...WILL
INDICATE A SLIGHT CHANCE OF SHOWER SHOWERS OVER WARREN/HALIFAX AND
EDGECOMBE COUNTIES BETWEEN 17-21Z...CONSISTENT WITH SIMULATED
REFLECTIVITY OUTPUT FROM THE 00Z HIGH RES WRF-NMM.

TONIGHT:
EXPECT CLEAR SKIES OVERNIGHT AS ARCTIC HIGH PRESSURE BUILDS DIRECTLY
OVER CENTRAL NC.  LOWS WILL BE DRIVEN BY A COMBINATION OF COLD
ADVECTION (EARLY ON) AND RADIATIONAL COOLING. WILL INDICATE LOWS
RANGING FROM THE MID/UPPER TEENS TO LOWER 20S. -VINCENT

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
AS OF 240 AM THURSDAY...

...A LIGHT WINTRY MIX STILL POSSIBLE FRIDAY AND FRIDAY EVENING...

THE TREND OF THE MODELS CONTINUES TO BE TOWARD A FLATTER MID/UPPER
WAVE SOLUTION AND VERY LIGHT QPF... FOR FRIDAY AND FRIDAY EVENING AS
THE SYSTEM MOVES THROUGH THE TENNESSEE AND LOWER OHIO VALLEY REGION
ACROSS THE APPALACHIANS TO THE MID-ATLANTIC COAST. VERY COLD ARCTIC
AIR WILL BE IN PLACE. HOWEVER... MOISTURE WILL BE LACKING FOR A
SIGNIFICANT WINTER STORM. YET... WITH SUCH COLD AIR IN PLACE FRIDAY
BEFORE THE LIGHT PRECIPITATION EVENT UNFOLDS... THIS COULD TURN OUT
TO BE A MINIMAL PRECIPITATION / BUT HIGH IMPACT EVENT (I.E. THE
19JAN2005 LIGHT SNOW / HIGH IMPACT EVENT)... WHEN RDU MEASURED 1
INCH OF SNOW WITH 0.04 LIQUID EQUIVALENT / WITH TEMPERATURES IN THE
MID 20S DURING THE AFTERNOON.

THE LATEST MODELS CONTINUE TO INDICATE LOW QPF IN THE RANGE OF 0.1
TO 0.2 OF AN INCH... WITH MOST ENSEMBLE MEMBERS IN THE 0.05 TO 0.15
RANGE. THE MAJORITY OF THE PRECIPITATION TIMING IS FORECAST TO BE IN
THE LATE MORNING OR EARLY AFTERNOON BEGIN TIME... EXCEPT DURING THE
AFTERNOON IN THE SOUTHEAST... ENDING QUICKLY BY LATE AFTERNOON OR
VERY EARLY EVENING.

ALTHOUGH THE MODEL 1000/850 AND 850/700 THICKNESS FORECASTS CONTINUE
TO SHOW DECENT SPREAD... THE FAVORED 00Z/EC CONTINUES TO INDICATE
THE PREDOMINATE P-TYPE TO BE LIGHT SNOW NW (1280/1535M THICKNESSES)
...LIGHT SNOW WITH SLEET IN THE I-64 CORRIDOR (PARTIALS IN THE 1280S
AND 1540S - ENDING WITH 1300 AND 1550 OR SO). SURFACE WET BULB
FORECASTS KEEP TEMPERATURES IN THE 20S ALL DAY FROM RALEIGH WEST AND
NORTH THROUGH THE PIEDMONT INTO THE BLUE RIDGE. THIS WILL BE THE
AREA WHERE MEASURABLE SNOW AND SLEET IS FAVORED... WITH A
CHANGE-OVER TO LIGHT FREEZING RAIN OR FREEZING DRIZZLE BY SUNSET OR
SO (AS WE LOSE SATURATION IN THE ICE NUCLEATION ZONE ALOFT).
SNOWFALL ACCUMULATIONS OF AROUND AN INCH APPEAR POSSIBLE. THIS IS
WHERE A WINTER WEATHER ADVISORY WILL LIKELY BE NEEDED FRIDAY INTO
FRIDAY EVENING IN LATER FORECASTS (ASSUMING THE MODELS DO NOT
COMPLETELY DRY UP).

IN THE CORRIDOR FROM THE FAR SOUTHERN PIEDMONT... NORTHERN SANDHILLS
AND MUCH OF THE CENTRAL COASTAL PLAIN... MAINLY TO THE NORTH OF A
LINE FROM LAURINBURG TO FAYETTEVILLE TO GOLDSBORO / SOUTH OF 1-64
SHOULD BEGIN WITH LIGHT SNOW/SLEET WITH A CHANGE-OVER TO LIGHT
FREEZING RAIN WITH TRACE SNOW/SLEET (PREDOMINATE P-TYPES). SURFACE
WET BULBS HERE ARE FORECAST TO REACH NEAR 32... PLACING THIS REGION
IN LIKELY ADVISORY CRITERIA AS WELL.

TO THE EAST AND SOUTH OF LAURINBURG TO FAYETTEVILLE TO GOLDSBORO...
A COLD LIGHT RAIN MIXED WITH SLEET IS EXPECTED WITH WET BULBS 33-34
OR SO DURING THE AFTERNOON.

BOTTOM LINE... DUE TO THE EXPECTED LIGHT NATURE OF THE PRECIPITATION
EPISODE AND THE VERY COLD AIR IN PLACE FRIDAY INTO FRIDAY EVENING...
THIS COULD VERY WELL TURN OUT TO BE A LOW PRECIPITATION... YET
RATHER HIGH IMPACT EVENT. MODEL TRENDS CONTINUE TO DAMPEN THE WAVE
AND LESSEN THE QPF WITH TIME... WHICH MAKES THIS ONLY A LOW TO
MODERATE CONFIDENCE FORECAST FOR AMOUNTS. P-TYPE AND COLD AIR ARE
HIGH CONFIDENCE... QPF IS LOW CONFIDENCE.

CLOUDY AND COLD FRIDAY WITH LIGHT SNOW LIKELY NW... LIGHT SNOW/SLEET
CENTRAL... AND MOSTLY LIGHT RAIN SE LATE MORNING THROUGH THE
AFTERNOON.  HIGHS 28 TO 35.

FRIDAY NIGHT... PATCHY FREEZING RAIN/FREEZING DRIZZLE POSSIBLE
EARLY... THEN CLEARING LATE. COLD WITH POTENTIAL BLACK ICE. LOWS IN
THE 20S.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 200 AM THURSDAY...

SATURDAY AND SUNDAY:

ANOTHER MODIFIED ARCTIC AIR MASS DRIVEN BY A 1035+ SURFACE HIGH WILL
DIVE SE ACROSS OUR REGION. THE COLDEST NIGHT WILL LIKELY BE SATURDAY
NIGHT... ALTHOUGH SUNDAY NIGHT WILL BE NEARLY AS COLD... BUT WITH
LIGHTER WINDS. EXPECT MOSTLY CLEAR SKIES WITH LOWS IN THE 15-20
RANGE. HIGHS IN THE MID 30S TO MID 40S NW TO SE.

A STOUT WARMING TREND WILL BEGIN MONDAY... THEN BE FELT IN FULL
FORCE BY TUE-WED. THE ARCTIC  HIGH SHIFTS QUICKLY OFFSHORE MONDAY...
FOLLOWED BY A MODERATING SW FLOW. HIGHS SHOULD SHOOT UP QUICKLY INTO
THE MID 50S TO LOWER 60S MONDAY... AND REACH THE 60S TUE-WED. MUCH
MILDER NIGHTS ARE EXPECTED AS WELL WITH LOWS IN THE MID 30S TO LOWER
40S BY TUE AND IN THE 40S WEDNESDAY.

THE NEXT CHANCE OF RAIN APPEARS TO BE WEDNESDAY AS A COLD FRONT
APPROACHES FROM THE WEST.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 215 AM THURSDAY...

24-HR TAF PERIOD:
VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. A POSSIBLE
EXCEPTION WILL BE THE RWI TERMINAL WHERE A BRIEF PERIOD OF MVFR
CEILINGS WILL BE POSSIBLE BETWEEN 15-20Z. THE BIGGEST AVIATION
CONCERN WILL BE STRONG NORTHERLY WINDS FOR SEVERAL HOURS IN THE WAKE
OF A COLD FRONTAL PASSAGE EXPECTED TO OCCUR BETWEEN 12-14Z THIS
MORNING...EARLIEST AT THE INT/GSO TERMINALS AND LATEST AT THE FAY
TERMINAL. GIVEN STRONG PRESSURE RISES AND 30-40 KT FLOW IN A RAPIDLY
DEEPENING MIXED LAYER BEHIND THE FRONT...EXPECT PEAK SUSTAINED WINDS
OUT OF THE N/NNW AT 15-25 KT WITH GUSTS AS HIGH AS 30-35 KT IN THE
IMMEDIATE 2-4 HOURS (BETWEEN 14-18Z) POST FROPA. WINDS WILL
GRADUALLY WEAKEN TO 10-15 KT BY 21Z THIS AFTERNOON...BECOMING CALM
BY 00Z.

LOOKING AHEAD:
DETERIORATING CONDITIONS ARE EXPECTED DURING THE DAY FRIDAY IN
ASSOCIATION WITH A WEAK LOW PRESSURE SYSTEM MOVING EAST ACROSS THE
REGION. EXPECT THAT CEILINGS WILL LOWER INTO THE MVFR CATEGORY
EVERYWHERE BETWEEN 15-21Z FRI (EARLIEST INT/GSO AND LATEST
FAY/RWI)...WITH LIGHT PRECIP AND POTENTIALLY IFR/LIFR CONDITIONS
ASSOCIATED WITH A COLD AIR DAMMING WEDGE DURING THE LATE AFTERNOON
AND EVENING. A WINTRY MIX IS EXPECTED AT THE INT/GSO/RDU/RWI
TERMINALS...AND IFR/LIFR CONDITIONS ASSOCIATED WITH THE CAD WEDGE
WOULD BE UNLIKELY TO IMPROVE UNTIL SATURDAY WHEN ARCTIC HIGH
PRESSURE BUILDS INTO THE CAROLINAS. -VINCENT

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...VINCENT





AREA FORECAST DISCUSSION

NWS NORMAN OK

 959 PM CST FRI JAN 25 2013

.DISCUSSION...
MAIN UPDATE THIS EVENING IS TO SKY COVER. HRRR AND NAM ARE BOTH
SHOWING A SIGNAL OF THE HIGHER HUMIDITY AT LOW LEVELS /AND
LIKELY THEREFORE STRATUS/ MOVING UP FROM NORTH TEXAS INTO SOUTH
CENTRAL AND CENTRAL OKLAHOMA OVERNIGHT. IT ALSO APPEARS THAT THIS
STRATUS WILL BE PERSISTENT INTO AT LEAST THE MORNING HOURS ON
SATURDAY.. SO HAVE ALSO UPDATED THE SKY GRIDS FOR TOMORROW.
OTHERWISE ONLY MINOR CHANGES WERE NEEDED.

&&

.PREV DISCUSSION... /ISSUED 500 PM CST FRI JAN 25 2013/

AVIATION...
ABUNDANT MID/HIGH CLOUDS WILL CONT TO STREAM ACROSS OKLAHOMA AND
WESTERN NORTH TEXAS OVERNIGHT INTO SATURDAY. LOW LEVEL WINDS WILL
BEGIN TO ADVECT LOW LEVEL MOISTURE BACK NORTHWARD AND COULD SEE
STRATUS DECK APPROACH I-44 CORRIDOR BY SATURDAY AFTN. LIGHT NORTHEAST
WINDS WILL GRADUALLY SHIFT BACK TO THE SOUTH/SOUTHEAST AND WILL
PICK UP IN SPEED... ESPECIALLY LATE IN THE FORECAST OUT WEST.

30

PREV DISCUSSION... /ISSUED 225 PM CST FRI JAN 25 2013/

DISCUSSION...
LOW STRATUS DECK HAS KEPT MUCH OF CENTRAL AND SOUTHERN OKLAHOMA
COOLER THAN EXPECTED TODAY...AS DRIER AIR CONTINUES TO MOVE IN
FROM THE NORTH...HAVE SEEN SLOW EROSION OF STRATUS THIS AFTERNOON.
THIS WILL CONTINUE THROUGH THE EVENING...AND EXPECT CLEARING SKIES
FROM NW TO SE...THOUGH SOME PARTS OF SE OK WILL REMAIN OVERCAST.
AHEAD OF UPPER LEVEL STORM SYSTEM...MID AND UPPER CLOUD COVER WILL
INCREASE THROUGH TONIGHT AND INTO TOMORROW. ABUNDANCE OF CLOUD
COVER WILL KEEP US FROM COOLING OFF TOO MUCH...ESPECIALLY OVER SE
OK...WHERE LOW STRATUS WILL LINGER THROUGH TOMORROW MORNING.

A MODEST UPPER WAVE WILL TRANSLATE ACROSS THE CENTRAL AND
SOUTHERN PLAINS SATURDAY INTO SUNDAY. THIS WILL BRING RAIN CHANCES
BACK TO THE FA...THOUGH THE BEST CHANCES WILL RESIDE ACROSS FAR
NORTH CENTRAL OKLAHOMA AND SRN KANSAS LATE SATURDAY NIGHT. NOT
EXPECTING ANY HEAVY RAINFALL WITH THIS EVENT...AND MOST AREAS THAT
DO GET RAIN WILL SEE FROM ONE TO POSSIBLY TWO TENTHS OF AN INCH OF
TOTAL RAINFALL. PERSISTENT WAA AND INCREASING MOISTURE WILL KEEP
LOWS MUCH ABOVE NORMAL TOMORROW NIGHT AND SUNDAY NIGHT.

AS THE UPPER WAVE EXITS...LEE TROUGH WILL DEVELOP OVER ERN
COLORADO. CONTINUING S/SE FLOW WILL PROMOTE MOISTURE AXIS ACROSS
THE ERN HALF OF OKLAHOMA. THIS AREA WILL LIKELY SEE CLOUDY AND
PERHAPS DRIZZLY CONDITIONS MONDAY INTO TUESDAY. PERSISTENT
SRLY/SWRLY FLOW WILL INDUCE MUCH ABOVE NORMAL HIGHS...WHICH MAY
CLIMB AS HIGH AS 80 DEGREES BY MONDAY.

AS A POTENT UPPER WAVE MOVES OVER THE AREA...WITH STRENGTHENING
SFC CYCLONE OVER THE UPPER MIDWEST...A COLD FRONT WILL BE FORCED
SOUTHWARD ON TUESDAY. AS THIS FRONT COLLIDES WITH THE RELATIVELY
WARM AND MOIST AIRMASS OVER SOUTHEAST OKLAHOMA...EXPECT A GOOD
CHANCE OF THUNDERSTORMS TUESDAY AFTERNOON. BASED ON EXPECTED
MOISTURE AND INSTABILITY...ALONG WITH FAVORABLE WIND
FIELDS...STRONG TO SEVERE STORMS WILL BE POSSIBLE TUESDAY
AFTERNOON...WITH PRIMARILY A HAIL/WIND THREAT. STORMS SHOULD
RAPIDLY MOVE EWD INTO THE MISSISSIPPI VALLEY REGION BY TUESDAY
NIGHT.

FOLLOWING THE COLD FRONT...A PERIOD OF SEASONABLY COOL AND DRY
CONDITIONS IS EXPECTED. LONGER RANGE MODELS HAVE COME INTO BETTER
AGREEMENT TODAY REGARDING POTENTIAL STORM SYSTEM TO MOVE ACROSS
THE SRN PLAINS LATE NEXT WEEK. FOR NOW...THE SYSTEM APPEARS TO
OFFER LITTLE CHANCE OF WINTRY PRECIP...OR ANY PRECIP AT ALL FOR
THAT MATTER...AND WILL KEEP FORECAST DRY FROM WEDNESDAY THROUGH
THE END OF THE PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK  31  54  48  67 /   0   0  40  30
HOBART OK         30  58  46  68 /   0   0  20   0
WICHITA FALLS TX  34  63  51  72 /  10   0  20  10
GAGE OK           29  57  46  72 /   0   0  30   0
PONCA CITY OK     28  58  47  67 /   0  10  60  50
DURANT OK         40  51  49  69 /  10  20  30  20

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&

$$



AREA FORECAST DISCUSSION

NWS GREENVILLE-SPARTANBURG SC

 114 AM EST THU JAN 24 2013

.SYNOPSIS...
COOL CANADIAN HIGH PRESSURE WILL CONTINUE OVER THE EASTERN STATES
TODAY. THIS HIGH WILL MOVE OFF THE EAST COAST EARLY FRIDAY AS A COLD
FRONT CROSSES TENNESSEE REACHING THE NORTH CAROLINA MOUNTAINS FRIDAY
AFTERNOON. ANOTHER CANADIAN HIGH PRESSURE WILL DOMINATE OUR WEATHER
THIS WEEKEND AND EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 1245 AM EST THURSDAY...HAVE MADE MINOR ADJUSTMENTS TO
TEMPERATURES AND DEW POINTS PER LATEST OBS. OTHERWISE...THE FORECAST
IS ON TRACK.

AS OF 945 PM...THE 00Z NAM AND 21Z SREF HAVE BACKED OFF ON THE
DEVELOPMENT OF PRECIP OVERNIGHT WITH THE WEAK CLIPPER SYSTEM MOVING
THRU. THE LAST SEVERAL RAP RUNS HAVE BEEN DRY...BUT THE 17Z LOCAL
WRF-ARW STILL HAVE SOME PRECIP...ALBEIT VERY LIGHT. THESE TRENDS
APPEAR TO BE VALID AS SAT PIX ONLY NOW SHOWING SOME LOW CLOUDS
FORMING TO OUR NW. THEREFORE...HAVE FOLLOWED THE TRENDS AND BACKED
OFF ON PRECIP FROM THE WWA FORCING AHEAD OF THE SYSTEM...BUT KEEP
PRECIP IN THE NW FLOW FORCING BEHIND THE SYSTEM. THIS MEANS ONLY A
SMALL CHC OF VERY LIGHT FREEZING RAIN WITH SNOW BEING THE MAIN
P-TYPE. IN ADDITION...WENT WITH THE P-TYPE NOMOGRAM METHOD OF
CREATING WX GRIDS INSTEAD OF TOP DOWN. THE NOMOGRAM SEEMS TO CAPTURE
THE PREVIOUS AND CURRENT THINKING OF FZRA TURNING TO SN BETTER THAN
THE TOP DOWN WHICH KEEPS MORE WIDESPREAD FZRA IN LONGER. OF
COURSE...GIVEN THE LACK OF PRECIP UPSTREAM...THIS COULD ALL JUST BE
AN EXERCISE IN FUTILITY. HAVE BACKED OFF ON QPF AS WELL GIVEN THE
LACK OF PRECIP UPSTREAM AND LATEST MDL GUIDANCE. THIS STILL GIVES A
TRACE OF GLAZE IN THE HIGHEST ELEVATIONS AND A DUSTING OF SNOW.
GIVEN THE OVERALL TRENDS AND LACK OF CONFIDENCE...IT STILL SEEMS AN
ADV IS NOT WARRANTED. THEREFORE...WILL JUST LET THE FORECAST SPEAK
FOR ITSELF WITH A BRIEF PERIOD OF POTENTIAL WINTRY PRECIP WITH
LITTLE TO NO ACCUM. HAD TO DROP LOWS ACROSS MUCH OF THE AREA AS
TEMPS WERE RUNNING COOLER THAN NORMAL. IT LOOKS LIKE WINDS ARE
PICKING UP ACROSS THE NRN MTNS...SO THE WIND ADV STILL SEEMS WELL
PLACED.

AS OF 645 PM...18Z MDLS CONTINUE TO SHOW PREVIOUS TRENDS OF WWA
FORCED PRECIP DEVELOPING ACROSS THE MTNS LATE THIS EVENING THEN
BECOMING DOMINATED BY NW FLOW PROCESSES BY MORNING. THEREFORE...THE
FCST POP AND P-TYPE TRENDS STILL LOOK GOOD. STILL EXPECT ONLY VERY
LIGHT PRECIP AMOUNTS...SO NO WINTER WX ADV IS EXPECTED. MAIN UPDATES
WERE FOR CURRENT CONDITIONS.

PREVIOUS DISCUSSION...A SHORT WAVE TROUGH WILL DIG SOUTHEAST TOWARD
THE OHIO VALLEY AND MID-ATLANTIC THIS EVENING...DEEPENING THE MEAN
LONG WAVE TROUGH OVER THE EASTERN CONUS AND REINFORCING THE
UNSEASONABLY COOL AIR MASS WITH ANOTHER (MOSTLY DRY) COLD FRONT.
HOWEVER...A WAA PATTERN DEVELOPING ACROSS THE TENN VALLEY WILL
RESULT IN SOME ENHANCED LOW LEVEL MOISTURE AHEAD OF THE FRONT. THIS
WILL BE AUGMENTED ACROSS THE WESTERN MOUNTAINS BY A STRONG WESTERLY
LOW LEVEL FLOW. THE FORCING TONIGHT WILL REMAIN WEAK...LIMITED TO
WEAK WAA AND A BIT OF AN UPSLOPE COMPONENT ALONG THE SPINE OF THE
APPALACHIANS...AND MOISTURE WILL BE SHALLOW. THEREFORE...POPS WILL
GENERALLY BE CONFINED TO THE COUNTIES BORDERING TENN...AND WILL BE
LIMITED TO THE 30-50 RANGE. P-TYPE IS SOMEWHAT PROBLEMATIC. TEMPS IN
THE MOIST LAYER DO NOT FALL BELOW -8 C UNTIL COLD ADVECTION
OVERTAKES THE AREA TOWARD 12Z. THIS DOES NOT ALWAYS TRANSLATE TO A
LACK OF SNOW DURING NW FLOW EVENTS (MAINLY DUE TO THE CONVECTIVE
NATURE OF THOSE EVENTS). HOWEVER...THE
/WARM SIDE/ OF TONIGHT/S EVENT WILL NOT BE A TRUE NW FLOW REGIME...
SO I THINK THIS IS A CASE IN WHICH -FZRA OR -FZDZ WILL BE THE
PRIMARY P-TYPE...UNTIL THE COLD FRONT SWEEPS THROUGH THE AREA...
AFTER WHICH WE WILL SEE A TRANSITION TO A BRIEF NW FLOW SNOW EVENT.
PRECIP RATES AND BRIEF DURATION OF THE EVENT SHOULD RESULT IN VERY
LIGHT ICE/SNOW ACCUMS. TRAVEL PROBLEMS COULD ARISE IF WE SEE A
COUPLE OF HOURS OF FREEZING DRIZZLE...WHICH COULD POTENTIALLY MAKE
THE ROADS A MESS IN AREAS RIGHT ALONG THE STATE LINE. THIS IS
POSSIBLE...BUT I/M NOT CONFIDENT ENOUGH TO ISSUE ANY PRODUCTS ATTM.
WE WILL CONTINUE TO MENTION THIS IN THE HWO.

THE OTHER CONCERN WILL BE THE WIND...AS H8 WINDS TURN TOWARD THE NW
TOWARD DAYBREAK AND STRENGTHEN IN THE STRONG COLD ADVECTION. WINDS
AT THE TOP OF THE MIXED LAYER INCREASE TO 45-55 KT ACROSS MUCH OF
THE MTNS AS A SURFACE LOW DEEPENS OFF THE NC COAST. HOWEVER...THE
SURFACE GRADIENT ACROSS THE MTNS NEVER EXCEEDS 5 OR 6 MB. WHILE THIS
DOES NOT FAVOR A HIGH WIND EVENT...A WIND ADVISORY SEEMS PRUDENT FOR
THE NORTHERN MTNS AND HIGH ELEVATIONS OF THE NORTHERN FOOTHILLS LATE
TONIGHT AND TOMORROW MORNING.

INCREASING CLOUDS AND PERSISTENT MIXING WILL RESULT IN MIN TEMPS
MUCH CLOSER TO NORMAL THAN WE HAVE SEEN THE PAST COUPLE OF MORNINGS.
DESPITE CLEARING SKIES DURING THE AFTERNOON THURSDAY...MAX TEMPS
WILL BE COOLER THAN TODAY/S READINGS (MUCH COOLER OVER THE MTNS)
OWING TO THE RESURGENCE OF COLD AIR.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AS OF MIDDAY WED...NOT MUCH GOING ON IN THE UPPER ATMOSPHERE TO START
THE PERIOD AT 00Z FRI...WITH A PRONOUNCED TROUGH SLIDING OFF INTO THE
ATLANTIC LEAVING QUASI-ZONAL FLOW IN PLACE ACROSS THE EAST BEFORE
NEXT TROUGH MOVES FROM THE NORTHERN PLAINS OVER THE MID-ATLANTIC
REGION LATE IN THE SHORT TERM PERIOD.

MOST OF THE ACTION WILL COME FROM LOW LEVEL FORCING ASSOCIATED WITH
SPRAWLING SFC HIGH SHIFTING FROM THE OHIO VALLEY ONTO THE EASTERN
SEABOARD THU NIGHT SETTING UP IN-SITU CAD ACROSS THE CAROLINAS. SFC
LOW DEVELOPS IN ITS WAKE OVER THE NRN PLAINS AT THAT
TIME...MAGNIFYING SOUTHERLY FLOW ACROSS THE LOWER MISS VALLEY AND
LEADING TO DEVELOPMENT OF PRECIP IN THE BAROCLINIC ZONE THERE. THE
LOW SHIFTS INTO THE GREAT LAKES REGION OVERNIGHT THU NIGHT PULLING
THE BEST ISENTROPIC LIFT AND MOISTURE ADVECTION INTO THE TENN VALLEY
BY EARLY FRI MORNING. AS NOTED YESTERDAY...NAM IS FIRST TO BRING
PRECIP INTO OUR SW MTNS WITH ACCUMULATIONS ALREADY BY DAYBREAK FRI.
HOWEVER THE ISENTROPIC LIFT WITH LOW CONDENSATION PRESSURE DEFICITS
IS SEEN ON THE GFS/EC PRIOR TO THAT TIME SO I FAVOR THE EARLY START.
THE RELATIVELY RAPID MOVEMENT OF THE LOW MEANS THE PRECIP SHOULD
SPREAD EAST QUICKLY AND NOT BE AN ESPECIALLY LONG DURATION EVENT.
QPF VALUES ARE HIGHEST FROM THE NAM...WHICH IS A LITTLE SURPRISING
GIVEN THE SLIGHTLY HIGHER PWATS SEEN ON THE GFS. FOR THE MOST
PART...FAVORED A BLEND OF HPC AND GFS GUIDANCE WHICH WERE FAIRLY
CLOSELY MATCHED.

THE TRACK OF THE LOW IS SUCH THAT IT COULD ERODE THE CAD WEDGE...AND
THE MODELS SHOW THIS. HOWEVER GIVEN THE PRE-EXISTING COLD AIR MASS
PRESENTLY IN PLACE AND PAST EXPERIENCE WITH HIGH PRESSURE CENTERS
FOLLOWING THIS TRACK...THE WEDGE COULD HOLD STRONG. THE NAM HOLDS ON
TO THE WEDGE THE LONGEST OF THE OPNL MODELS AND ALSO HAS THE COOLEST
RAW TEMPS. THAT SEEMS LIKE THE MOST PLAUSIBLE SOLUTION SO I FAVORED A
BLEND OF RAW NAM AND NAM MOS TEMPS FRIDAY...ALONG WITH NAM THERMAL
PROFILES THROUGH THE EVENT. WITH THE STRONG WARM ADVECTION OVERRIDING
THE COLD WEDGE...MOST OF THE CWFA LOOKS TO GET MOSTLY FREEZING RAIN.
SOME SLEET WILL OCCUR FURTHER NORTH WHERE THE WARM NOSE WILL NOT BE
QUITE AS STRONG PER BOURGOUIN PTYPE TECHNIQUE...WITH MOSTLY TO ALL
SNOW ACROSS OUR NORTHERN TIER OF COUNTIES.

AS THE SFC LOW MOVES INTO THE MID-ATLANTIC AND TURNS FLOW WESTERLY
ACROSS THE REGION...MOISTURE AND WARMER AIR ARE PUSHED OUT OF THE
PIEDMONT BY FRI EVENING. UPSLOPE WILL ALLOW CONTINUING PRECIP IN THE
MTNS. THE SHALLOW MOIST LAYER IS TOO WARM FOR ICE NUCLEATION SO
FREEZING RAIN SHOULD RESULT...THOUGH WITH ONLY VERY SMALL ADDITIONAL
ACCUMULATION. SAID PCPN IS EXPECTED TO BE CONFINED TO PRIME UPSLOPE
AREAS IN THE NRN NC MTNS AND DIMINISH BY MID MORNING SAT. HIGHS WILL
REBOUND A BIT OVER THE PIEDMONT GIVEN THE SUNSHINE...BUT STILL
SEVERAL DEGREES BELOW NORMAL.

THERE IS RELATIVELY HIGH CONFIDENCE IN THE FRIDAY EVENT PRODUCING
WINTER WX ACROSS THE REGION. THE SOUTHWEST MOUNTAINS LOOK TO RECEIVE
ICE ACCUMULATION OF A QUARTER INCH OR MORE ESPECIALLY AT HIGHER
ELEVATIONS. TOGETHER THESE POINTS WARRANT A WINTER STORM WATCH FOR
THAT AREA. TEMPERATURES REMAIN SOMEWHAT CRITICAL DURING THE DAY
FRIDAY. IF TEMPS ARE ABLE TO WARM SUFFICIENTLY BEFORE THE BULK OF
THE PRECIP ARRIVES...THE AREA MAY SEE LARGELY RAIN AND ICE ACCUMS
MAY BE LIMITED. THE CURRENT FCST TEMP AND PRECIP TRENDS SUPPORT THE
WATCH DESPITE HAVING AFTERNOON TEMPS ABOVE FREEZING AND RAIN AT THAT
TIME.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AT 1430 EST WEDNESDAY...AN UPPER TROUGH WILL PROGRESS AWAY FROM THE
COAST SATURDAY NIGHT...WHILE AN UPPER RIDGE AMPLIFIES OVER THE
PLAINS. THIS RIDGE SLOWLY PROGRESSES TO THE EASTERN USA BY EARLY
NEXT WEEK. SURFACE HIGH PRESSURE BEHIND A DEPARTING COLD FRONT WILL
MOVE TO THE APPALACHIANS BY SUNDAY...THEN TO THE MID ATLANTIC COAST
BY MONDAY. MOIST GULF INFLOW ON THE BACK SIDE OF THIS HIGH WILL
REACH OUR AREA MONDAY AND TUESDAY...WHILE THE HIGH MOVES OFFSHORE.
GULF INFLOW WILL DIMINISH WEDNESDAY WITH A WEAKENING PRESSURE
GRADIENT...WHILE A COLD FRONT APPROACHES FORM THE NORTHWEST. THE
FRONT CROSSES OUR AREA DURING THE DAY...FOLLOWED BY MOIST NW FLOW
INTO THE NC MOUNTAINS...WHERE TEMPERATURES SHOULD STILL SUPPORT
LIQUID PRECIPITATION IN THE AFTERNOON.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AT KCLT AND OTHER PIEDMONT/FOOTHILLS TERMINALS...VFR THROUGH THE TAF
PERIOD. A DRY COLD FRONT WILL SLIP SOUTHEAST THROUGH THE AREA EARLY
THURSDAY MORNING. AHEAD OF AN APPROACHING FRONT...MOISTURE WILL
INCREASE OVERNIGHT HOURS. MODEL SOUNDING/TIME HEIGHTS SUGGEST
CONSIDERABLE AMOUNTS OF HIGH CLOUDS WILL SPREAD OVERHEAD THROUGH
THUR MORNING WITH SOME LOW VFR CEILING STRATUS POSSIBLE OVER THE
NORTHERN NC PIEDMONT. WINDS WILL VEER FROM SW TO NW/N IN THE WAKE OF
THE FRONTAL PASSAGE. AS CANADIAN HIGH PRESSURE BUILDS BEHIND IN THE
FRONT THURSDAY...GUSTY N WINDS OF 15-20KT WILL OCCUR LATE THUR
MORNING THROUGH MIDDAY MAINLY OVER THE NC PIEDMONT AFFECTING KCLT
AND KHKY. GUSTS DIMINISH BY LATE AFTERNOON WITH WINDS BECOMING NE.
SKY WILL REMAIN MOSTLY CLEAR THUR INTO THUR NIGHT.

AT KAVL...MOISTURE INCREASING AHEAD OF A COLD FRONT SHOULD RESULT IN
LOW VFR STRATOCU. NW GUSTS AROUND 20 KTS ARE EXPECTED BY DAYBREAK
WITH 30 KT GUSTS COMMON AFTER SUNRISE THURSDAY. CLOUDS SHOULD
GRADUALLY DISSIPATE BY MIDDAY THURSDAY WITH GUSTY N WINDS
DIMINISHING BY EVENING.

OUTLOOK...A COLD FRONT WILL MOVE THROUGH FRIDAY WITH FLIGHT
RESTRICTIONS AND A WINTRY MIX LIKELY. DRY HIGH PRESSURE WILL RETURN
BY SATURDAY WITH MORE VFR CONDITIONS...PERSISTING INTO MONDAY.

AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT THE FOLLOWING LINK (USE LOWER CASE)...

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
FUEL MOISTURE AND MINIMUM RELATIVE HUMIDITY VALUES WILL BE CLOSE TO
FIRE DANGER STATEMENT CRITERIA IN NE GA ON THURSDAY.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING
     FOR GAZ010-017.
NC...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING
     FOR NCZ051-052-058-059-062>065.
     WIND ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NCZ033-049-050-
     501-503-505.
SC...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING
     FOR SCZ001>003.

&&

$$
SYNOPSIS...JPT
NEAR TERM...JOH/RWH
SHORT TERM...WIMBERLEY
LONG TERM...JAT
AVIATION...JOH
FIRE WEATHER...






AREA FORECAST DISCUSSION

NWS GREENVILLE-SPARTANBURG SC

 108 AM EST THU JAN 24 2013

.SYNOPSIS...
COOL CANADIAN HIGH PRESSURE WILL CONTINUE OVER THE EASTERN STATES
TODAY. THIS HIGH WILL MOVE OFF THE EAST COAST EARLY FRIDAY AS A COLD
FRONT CROSSES TENNESSEE REACHING THE NORTH CAROLINA MOUNTAINS FRIDAY
AFTERNOON. ANOTHER CANADIAN HIGH PRESSURE WILL DOMINATE OUR WEATHER
THIS WEEKEND AND EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 945 PM...THE 00Z NAM AND 21Z SREF HAVE BACKED OFF ON THE
DEVELOPMENT OF PRECIP OVERNIGHT WITH THE WEAK CLIPPER SYSTEM MOVING
THRU. THE LAST SEVERAL RAP RUNS HAVE BEEN DRY...BUT THE 17Z LOCAL
WRF-ARW STILL HAVE SOME PRECIP...ALBEIT VERY LIGHT. THESE TRENDS
APPEAR TO BE VALID AS SAT PIX ONLY NOW SHOWING SOME LOW CLOUDS
FORMING TO OUR NW. THEREFORE...HAVE FOLLOWED THE TRENDS AND BACKED
OFF ON PRECIP FROM THE WWA FORCING AHEAD OF THE SYSTEM...BUT KEEP
PRECIP IN THE NW FLOW FORCING BEHIND THE SYSTEM. THIS MEANS ONLY A
SMALL CHC OF VERY LIGHT FREEZING RAIN WITH SNOW BEING THE MAIN
P-TYPE. IN ADDITION...WENT WITH THE P-TYPE NOMOGRAM METHOD OF
CREATING WX GRIDS INSTEAD OF TOP DOWN. THE NOMOGRAM SEEMS TO CAPTURE
THE PREVIOUS AND CURRENT THINKING OF FZRA TURNING TO SN BETTER THAN
THE TOP DOWN WHICH KEEPS MORE WIDESPREAD FZRA IN LONGER. OF
COURSE...GIVEN THE LACK OF PRECIP UPSTREAM...THIS COULD ALL JUST BE
AN EXERCISE IN FUTILITY. HAVE BACKED OFF ON QPF AS WELL GIVEN THE
LACK OF PRECIP UPSTREAM AND LATEST MDL GUIDANCE. THIS STILL GIVES A
TRACE OF GLAZE IN THE HIGHEST ELEVATIONS AND A DUSTING OF SNOW.
GIVEN THE OVERALL TRENDS AND LACK OF CONFIDENCE...IT STILL SEEMS AN
ADV IS NOT WARRANTED. THEREFORE...WILL JUST LET THE FORECAST SPEAK
FOR ITSELF WITH A BRIEF PERIOD OF POTENTIAL WINTRY PRECIP WITH
LITTLE TO NO ACCUM. HAD TO DROP LOWS ACROSS MUCH OF THE AREA AS
TEMPS WERE RUNNING COOLER THAN NORMAL. IT LOOKS LIKE WINDS ARE
PICKING UP ACROSS THE NRN MTNS...SO THE WIND ADV STILL SEEMS WELL
PLACED.

AS OF 645 PM...18Z MDLS CONTINUE TO SHOW PREVIOUS TRENDS OF WWA
FORCED PRECIP DEVELOPING ACROSS THE MTNS LATE THIS EVENING THEN
BECOMING DOMINATED BY NW FLOW PROCESSES BY MORNING. THEREFORE...THE
FCST POP AND P-TYPE TRENDS STILL LOOK GOOD. STILL EXPECT ONLY VERY
LIGHT PRECIP AMOUNTS...SO NO WINTER WX ADV IS EXPECTED. MAIN UPDATES
WERE FOR CURRENT CONDITIONS.

PREVIOUS DISCUSSION...A SHORT WAVE TROUGH WILL DIG SOUTHEAST TOWARD
THE OHIO VALLEY AND MID-ATLANTIC THIS EVENING...DEEPENING THE MEAN
LONG WAVE TROUGH OVER THE EASTERN CONUS AND REINFORCING THE
UNSEASONABLY COOL AIR MASS WITH ANOTHER (MOSTLY DRY) COLD FRONT.
HOWEVER...A WAA PATTERN DEVELOPING ACROSS THE TENN VALLEY WILL
RESULT IN SOME ENHANCED LOW LEVEL MOISTURE AHEAD OF THE FRONT. THIS
WILL BE AUGMENTED ACROSS THE WESTERN MOUNTAINS BY A STRONG WESTERLY
LOW LEVEL FLOW. THE FORCING TONIGHT WILL REMAIN WEAK...LIMITED TO
WEAK WAA AND A BIT OF AN UPSLOPE COMPONENT ALONG THE SPINE OF THE
APPALACHIANS...AND MOISTURE WILL BE SHALLOW. THEREFORE...POPS WILL
GENERALLY BE CONFINED TO THE COUNTIES BORDERING TENN...AND WILL BE
LIMITED TO THE 30-50 RANGE. P-TYPE IS SOMEWHAT PROBLEMATIC. TEMPS IN
THE MOIST LAYER DO NOT FALL BELOW -8 C UNTIL COLD ADVECTION
OVERTAKES THE AREA TOWARD 12Z. THIS DOES NOT ALWAYS TRANSLATE TO A
LACK OF SNOW DURING NW FLOW EVENTS (MAINLY DUE TO THE CONVECTIVE
NATURE OF THOSE EVENTS). HOWEVER...THE
/WARM SIDE/ OF TONIGHT/S EVENT WILL NOT BE A TRUE NW FLOW REGIME...
SO I THINK THIS IS A CASE IN WHICH -FZRA OR -FZDZ WILL BE THE
PRIMARY P-TYPE...UNTIL THE COLD FRONT SWEEPS THROUGH THE AREA...
AFTER WHICH WE WILL SEE A TRANSITION TO A BRIEF NW FLOW SNOW EVENT.
PRECIP RATES AND BRIEF DURATION OF THE EVENT SHOULD RESULT IN VERY
LIGHT ICE/SNOW ACCUMS. TRAVEL PROBLEMS COULD ARISE IF WE SEE A
COUPLE OF HOURS OF FREEZING DRIZZLE...WHICH COULD POTENTIALLY MAKE
THE ROADS A MESS IN AREAS RIGHT ALONG THE STATE LINE. THIS IS
POSSIBLE...BUT I/M NOT CONFIDENT ENOUGH TO ISSUE ANY PRODUCTS ATTM.
WE WILL CONTINUE TO MENTION THIS IN THE HWO.

THE OTHER CONCERN WILL BE THE WIND...AS H8 WINDS TURN TOWARD THE NW
TOWARD DAYBREAK AND STRENGTHEN IN THE STRONG COLD ADVECTION. WINDS
AT THE TOP OF THE MIXED LAYER INCREASE TO 45-55 KT ACROSS MUCH OF
THE MTNS AS A SURFACE LOW DEEPENS OFF THE NC COAST. HOWEVER...THE
SURFACE GRADIENT ACROSS THE MTNS NEVER EXCEEDS 5 OR 6 MB. WHILE THIS
DOES NOT FAVOR A HIGH WIND EVENT...A WIND ADVISORY SEEMS PRUDENT FOR
THE NORTHERN MTNS AND HIGH ELEVATIONS OF THE NORTHERN FOOTHILLS LATE
TONIGHT AND TOMORROW MORNING.

INCREASING CLOUDS AND PERSISTENT MIXING WILL RESULT IN MIN TEMPS
MUCH CLOSER TO NORMAL THAN WE HAVE SEEN THE PAST COUPLE OF MORNINGS.
DESPITE CLEARING SKIES DURING THE AFTERNOON THURSDAY...MAX TEMPS
WILL BE COOLER THAN TODAY/S READINGS (MUCH COOLER OVER THE MTNS)
OWING TO THE RESURGENCE OF COLD AIR.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AS OF MIDDAY WED...NOT MUCH GOING ON IN THE UPPER ATMOSPHERE TO START
THE PERIOD AT 00Z FRI...WITH A PRONOUNCED TROUGH SLIDING OFF INTO THE
ATLANTIC LEAVING QUASI-ZONAL FLOW IN PLACE ACROSS THE EAST BEFORE
NEXT TROUGH MOVES FROM THE NORTHERN PLAINS OVER THE MID-ATLANTIC
REGION LATE IN THE SHORT TERM PERIOD.

MOST OF THE ACTION WILL COME FROM LOW LEVEL FORCING ASSOCIATED WITH
SPRAWLING SFC HIGH SHIFTING FROM THE OHIO VALLEY ONTO THE EASTERN
SEABOARD THU NIGHT SETTING UP IN-SITU CAD ACROSS THE CAROLINAS. SFC
LOW DEVELOPS IN ITS WAKE OVER THE NRN PLAINS AT THAT
TIME...MAGNIFYING SOUTHERLY FLOW ACROSS THE LOWER MISS VALLEY AND
LEADING TO DEVELOPMENT OF PRECIP IN THE BAROCLINIC ZONE THERE. THE
LOW SHIFTS INTO THE GREAT LAKES REGION OVERNIGHT THU NIGHT PULLING
THE BEST ISENTROPIC LIFT AND MOISTURE ADVECTION INTO THE TENN VALLEY
BY EARLY FRI MORNING. AS NOTED YESTERDAY...NAM IS FIRST TO BRING
PRECIP INTO OUR SW MTNS WITH ACCUMULATIONS ALREADY BY DAYBREAK FRI.
HOWEVER THE ISENTROPIC LIFT WITH LOW CONDENSATION PRESSURE DEFICITS
IS SEEN ON THE GFS/EC PRIOR TO THAT TIME SO I FAVOR THE EARLY START.
THE RELATIVELY RAPID MOVEMENT OF THE LOW MEANS THE PRECIP SHOULD
SPREAD EAST QUICKLY AND NOT BE AN ESPECIALLY LONG DURATION EVENT.
QPF VALUES ARE HIGHEST FROM THE NAM...WHICH IS A LITTLE SURPRISING
GIVEN THE SLIGHTLY HIGHER PWATS SEEN ON THE GFS. FOR THE MOST
PART...FAVORED A BLEND OF HPC AND GFS GUIDANCE WHICH WERE FAIRLY
CLOSELY MATCHED.

THE TRACK OF THE LOW IS SUCH THAT IT COULD ERODE THE CAD WEDGE...AND
THE MODELS SHOW THIS. HOWEVER GIVEN THE PRE-EXISTING COLD AIR MASS
PRESENTLY IN PLACE AND PAST EXPERIENCE WITH HIGH PRESSURE CENTERS
FOLLOWING THIS TRACK...THE WEDGE COULD HOLD STRONG. THE NAM HOLDS ON
TO THE WEDGE THE LONGEST OF THE OPNL MODELS AND ALSO HAS THE COOLEST
RAW TEMPS. THAT SEEMS LIKE THE MOST PLAUSIBLE SOLUTION SO I FAVORED A
BLEND OF RAW NAM AND NAM MOS TEMPS FRIDAY...ALONG WITH NAM THERMAL
PROFILES THROUGH THE EVENT. WITH THE STRONG WARM ADVECTION OVERRIDING
THE COLD WEDGE...MOST OF THE CWFA LOOKS TO GET MOSTLY FREEZING RAIN.
SOME SLEET WILL OCCUR FURTHER NORTH WHERE THE WARM NOSE WILL NOT BE
QUITE AS STRONG PER BOURGOUIN PTYPE TECHNIQUE...WITH MOSTLY TO ALL
SNOW ACROSS OUR NORTHERN TIER OF COUNTIES.

AS THE SFC LOW MOVES INTO THE MID-ATLANTIC AND TURNS FLOW WESTERLY
ACROSS THE REGION...MOISTURE AND WARMER AIR ARE PUSHED OUT OF THE
PIEDMONT BY FRI EVENING. UPSLOPE WILL ALLOW CONTINUING PRECIP IN THE
MTNS. THE SHALLOW MOIST LAYER IS TOO WARM FOR ICE NUCLEATION SO
FREEZING RAIN SHOULD RESULT...THOUGH WITH ONLY VERY SMALL ADDITIONAL
ACCUMULATION. SAID PCPN IS EXPECTED TO BE CONFINED TO PRIME UPSLOPE
AREAS IN THE NRN NC MTNS AND DIMINISH BY MID MORNING SAT. HIGHS WILL
REBOUND A BIT OVER THE PIEDMONT GIVEN THE SUNSHINE...BUT STILL
SEVERAL DEGREES BELOW NORMAL.

THERE IS RELATIVELY HIGH CONFIDENCE IN THE FRIDAY EVENT PRODUCING
WINTER WX ACROSS THE REGION. THE SOUTHWEST MOUNTAINS LOOK TO RECEIVE
ICE ACCUMULATION OF A QUARTER INCH OR MORE ESPECIALLY AT HIGHER
ELEVATIONS. TOGETHER THESE POINTS WARRANT A WINTER STORM WATCH FOR
THAT AREA. TEMPERATURES REMAIN SOMEWHAT CRITICAL DURING THE DAY
FRIDAY. IF TEMPS ARE ABLE TO WARM SUFFICIENTLY BEFORE THE BULK OF
THE PRECIP ARRIVES...THE AREA MAY SEE LARGELY RAIN AND ICE ACCUMS
MAY BE LIMITED. THE CURRENT FCST TEMP AND PRECIP TRENDS SUPPORT THE
WATCH DESPITE HAVING AFTERNOON TEMPS ABOVE FREEZING AND RAIN AT THAT
TIME.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AT 1430 EST WEDNESDAY...AN UPPER TROUGH WILL PROGRESS AWAY FROM THE
COAST SATURDAY NIGHT...WHILE AN UPPER RIDGE AMPLIFIES OVER THE
PLAINS. THIS RIDGE SLOWLY PROGRESSES TO THE EASTERN USA BY EARLY
NEXT WEEK. SURFACE HIGH PRESSURE BEHIND A DEPARTING COLD FRONT WILL
MOVE TO THE APPALACHIANS BY SUNDAY...THEN TO THE MID ATLANTIC COAST
BY MONDAY. MOIST GULF INFLOW ON THE BACK SIDE OF THIS HIGH WILL
REACH OUR AREA MONDAY AND TUESDAY...WHILE THE HIGH MOVES OFFSHORE.
GULF INFLOW WILL DIMINISH WEDNESDAY WITH A WEAKENING PRESSURE
GRADIENT...WHILE A COLD FRONT APPROACHES FORM THE NORTHWEST. THE
FRONT CROSSES OUR AREA DURING THE DAY...FOLLOWED BY MOIST NW FLOW
INTO THE NC MOUNTAINS...WHERE TEMPERATURES SHOULD STILL SUPPORT
LIQUID PRECIPITATION IN THE AFTERNOON.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AT KCLT AND OTHER PIEDMONT/FOOTHILLS TERMINALS...VFR THROUGH THE TAF
PERIOD. A DRY COLD FRONT WILL SLIP SOUTHEAST THROUGH THE AREA EARLY
THURSDAY MORNING. AHEAD OF AN APPROACHING FRONT...MOISTURE WILL
INCREASE OVERNIGHT HOURS. MODEL SOUNDING/TIME HEIGHTS SUGGEST
CONSIDERABLE AMOUNTS OF HIGH CLOUDS WILL SPREAD OVERHEAD THROUGH
THUR MORNING WITH SOME LOW VFR CEILING STRATUS POSSIBLE OVER THE
NORTHERN NC PIEDMONT. WINDS WILL VEER FROM SW TO NW/N IN THE WAKE OF
THE FRONTAL PASSAGE. AS CANADIAN HIGH PRESSURE BUILDS BEHIND IN THE
FRONT THURSDAY...GUSTY N WINDS OF 15-20KT WILL OCCUR LATE THUR
MORNING THROUGH MIDDAY MAINLY OVER THE NC PIEDMONT AFFECTING KCLT
AND KHKY. GUSTS DIMINISH BY LATE AFTERNOON WITH WINDS BECOMING NE.
SKY WILL REMAIN MOSTLY CLEAR THUR INTO THUR NIGHT.

AT KAVL...MOISTURE INCREASING AHEAD OF A COLD FRONT SHOULD RESULT IN
LOW VFR STRATOCU. NW GUSTS AROUND 20 KTS ARE EXPECTED BY DAYBREAK
WITH 30 KT GUSTS COMMON AFTER SUNRISE THURSDAY. CLOUDS SHOULD
GRADUALLY DISSIPATE BY MIDDAY THURSDAY WITH GUSTY N WINDS
DIMINISHING BY EVENING.

OUTLOOK...A COLD FRONT WILL MOVE THROUGH FRIDAY WITH FLIGHT
RESTRICTIONS AND A WINTRY MIX LIKELY. DRY HIGH PRESSURE WILL RETURN
BY SATURDAY WITH MORE VFR CONDITIONS...PERSISTING INTO MONDAY.

AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT THE FOLLOWING LINK (USE LOWER CASE)...

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
FUEL MOISTURE AND MINIMUM RELATIVE HUMIDITY VALUES WILL BE CLOSE TO
FIRE DANGER STATEMENT CRITERIA IN NE GA ON THURSDAY.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING
     FOR GAZ010-017.
NC...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING
     FOR NCZ051-052-058-059-062>065.
     WIND ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NCZ033-049-050-
     501-503-505.
SC...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING
     FOR SCZ001>003.

&&

$$
SYNOPSIS...JPT
NEAR TERM...JDL/RWH
SHORT TERM...WIMBERLEY
LONG TERM...JAT
AVIATION...JOH
FIRE WEATHER...







AREA FORECAST DISCUSSION

NWS HOUSTON/GALVESTON TX

 950 PM CST FRI JAN 25 2013

.DISCUSSION...
AT 9 PM...THE WEAK COLD FRONT HAD MOVED THROUGH BRENHAM AND WAS
APPROACHING COLLEGE STATION...MADISONVILLE...AND CROCKETT. THE
LATEST HIGH RES AND RAP MODELS ALL INDICATE THAT THE FRONT WILL
SINK SOUTHWARD A BIT OVERNIGHT TONIGHT BEFORE MOVING BACK
NORTHWARD ON SATURDAY. A BIT OF A LOW-LEVEL JET HAS FORMED THIS
EVENING AS SHOWN ON THE KHGX AND THOU VAD WIND PROFILES JUST ABOVE
1000 FEET. SOME SLIGHTLY DRIER AIR WAS LOCATED OVER GALVESTON BAY
AND THE IMMEDIATE COASTAL AREAS EAST OF FREEPORT. THE MODELS
ACTUALLY CONTINUE THIS TREND THROUGH THE NIGHT. IN ADDITION TO
THE POSSIBLE LOW CLOUDS...HIGHER LEVEL CLOUDS WILL MOVE OVERHEAD
FOR AT LEAST THE NEXT FEW HOURS. BECAUSE OF THESE LIMITING
FACTORS...FELT THAT THE FOG THREAT IS NOW LOWER THAN EARLIER
ANTICIPATED. HOWEVER...THERE ARE A FEW CAVEATS. IF THE FRONT SAGS
A BIT FURTHER TO THE SOUTH IT WILL HELP POOL THE LOW-LEVEL
MOISTURE A BIT HIGHER. THIS MAY THEN HELP BACK THE WINDS A BIT TO
BE MORE FROM THE EAST-SOUTHEAST. IF THESE EVENTS OCCUR...THE
CHANCES FOR SEA FOG FORMATION WILL INCREASE.

HOWEVER...FOR NOW UPDATED THE WEATHER TO TAKE OUT THE DENSE FOG
AND TO GO WITH JUST PATCHY FOG. ALSO UPDATED THE CLOUD COVER...
DEWPOINTS...AND HUMIDITY.

40

&&

.PREV DISCUSSION... /ISSUED 557 PM CST FRI JAN 25 2013/

DISCUSSION...
00Z TAF DISCUSSION IN AVIATION SECTION.

AVIATION...
AS HAS BEEN THE CASE FOR THE BETTER HALF OF A WEEK...FOG WILL BE
THE MAIN AVIATION CONCERN FOR THE TAFS. PREVIOUS TAF PACKAGE MAY
HAVE BEEN TOO PESSIMISTIC SO THERE WILL BE SOME FURTHER
MODIFICATIONS GOING TOWARDS 06Z TAF CYCLE. FOR NOW WILL KEEP SOME
MENTION OF LIFR/IFR CIGS BUT LOOKING AT WIND FIELDS FROM THE S/SW
AND TD NOT AS HIGH AS FORECASTED...HAVE SOME DOUBTS TO HOW MUCH
FOG WILL DEVELOP. THINK LOW VSBY FOG WILL BE CONFINED TO COAST BUT
HOW MUCH FARTHER IT DEVELOPS IS THE MAIN QUESTION. WILL KEEP LIFR
MENTIONED FOR KHOU BUT ONLY MENTION IFR CIG AT KIAH. SEEMS MODEL
TRENDS MAY BE POINTING TO NOT BEING AS PESSIMISTIC WITH FOG AND
NOT TURNING WINDS TO THE SE AS MUCH AS PREVIOUSLY PROGGED. WILL
MONITOR 00Z GUIDANCE AND LIKELY MAKE FURTHER MODIFICATIONS TO TAFS
BASED OFF 00Z GUIDANCE AND ONGOING TRENDS.

39

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      58  75  59  74  63 /  10  10  10  10  20
HOUSTON (IAH)              61  77  60  75  63 /  10  10  10  10  20
GALVESTON (GLS)            59  72  61  71  62 /  10  10  10  10  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

DISCUSSION...40
AVIATION/MARINE...39



AREA FORECAST DISCUSSION

NWS FORT WORTH TX

 1202 PM CST THU JAN 24 2013

.AVIATION...
MAIN AVIATION FORECAST CONCERN CENTERS ON THE TIMING AND SOUTHWARD
EXTENT OF COLD FRONT CURRENTLY LOCATED OVER EXTREME SRN OK/WRN N
TX. THIS BOUNDARY HAS SHOWN LITTLE SWD MOTION IN THE PAST 4
HOURS. HOWEVER...BASED ON VERY MODEST SHORT-TERM PRESSURE RISES
OVER W OK...BELIEVE IT WILL HAVE ENOUGH MOMENTUM TO REACH THE
METROPLEX TAF SITES DURING THE 02-03Z TIMEFRAME. THIS WILL RESULT
IN A SHIFT TO LIGHT NORTHERLY WINDS IN THIS AREA. EXTENSIVE POST-
FRONTAL STRATUS OVER OK WILL REMAIN N OF THE METROPLEX UNTIL 08Z
OR LATER...AT WHICH TIME MVFR CEILINGS WILL LIKELY MOVE INTO THE
AREA AND PERSIST THRU AT LEAST MID MORNING FRIDAY.

IN THE WACO AREA...EXPECT VFR CONDITIONS UNTIL 09Z...AT WHICH TIME
STRATUS/AREAS OF FOG WILL LIKELY DEVELOP AS IN PREVIOUS MORNINGS.
COLD FRONT WILL BE MUCH DELAYED IN REACHING KACT...BUT DO EXPECT
ARRIVAL...AND ASSOCIATED NORTHERLY WIND SHIFT BY AROUND FRI/15Z.

66

&&

.UPDATE...
THE DENSE FOG ADVISORY WAS ALLOWED TO EXPIRE AT 10 AM. PATCHY FOG
PERSISTS IN A FEW OF THE EASTERN AND NORTHERN AREAS...BUT
VISIBILITIES WILL CONTINUE TO IMPROVE LATE THIS MORNING.

THE COLD FRONT WAS LOCATED VERY CLOSE TO THE RED RIVER ON THE 16Z
ANALYSIS AND HAS SHOWN A VERY SLOW SOUTHWARD PROGRESSION. THE
FRONT IS EXPECTED TO CONTINUE A SLOW SOUTHWARD PUSH AS PER OUR
CURRENT FORECAST. THE TIGHT TEMPERATURE GRADIENT NEAR THE FRONT
WILL PLAY HAVOC WITH THE TEMPERATURE FORECAST TODAY AND TONIGHT.
EXPECT TEMPERATURES TO REMAIN OR FALL INTO THE UPPER 50S NORTH OF
THE FRONT...WITH TEMPERATURES SOARING WELL INTO THE 70S IN MOST
AREAS SOUTH OF THE FRONT.

MORNING SOUNDING HERE IN FORT WORTH SUGGESTS THAT TEMPERATURES
WILL LIKELY RISE SLIGHTLY ABOVE THE PREVIOUS FORECAST HIGH
TEMPERATURES IN AREAS SOUTH OF THE SLOWLY ADVANCING COLD FRONT. WE
EXPECT AREAS THAT WILL RECEIVE NEARLY FULL SUN THIS AFTERNOON WILL
APPROACH 80F AS WINDS TEND TO VEER TO SOUTHWEST OR WEST AHEAD OF
THE FRONT. THE RECORD HIGH AT DFW TODAY IS 82...AND THE RECORD
HIGH AT WACO IS 83. THE CURRENT FORECASTS FOR THIS AFTERNOON AT
DFW /79F/ AND AT WACO /80F/ WILL FALL A FEW DEGREES SHORT OF THE
RECORD HIGHS.

IN THE EASTERN ZONES...GENERALLY EAST OF A LINE FROM
MCKINNEY TO HEARNE...THE LOW CLOUDS WILL HOLD HIGH TEMPERATURES
DOWN INTO THE UPPER 60S AND LOWER 70S. AND TEMPERATURES IN THE
COUNTIES ALONG THE RED RIVER WILL BE DEPENDENT ON THE EXACT
POSITION OF THE FRONT AS DISCUSSED ABOVE.

NO CHANGES TO LATER PERIODS OF FORECAST AT THIS TIME.

09/GP

&&

.PREV DISCUSSION... /ISSUED 339 AM CST THU JAN 24 2013/
UPPER LEVEL RIDGE IS NOW CENTERED SOUTHWEST OF THE AREA WITH HIGH
CLOUDS STREAMING OVER THE TOP OF THE RIDGE AND INTO THE STATE. AT
THE SURFACE...SOME STRATUS CLOUDS ARE NOW DEVELOPING ACROSS
SOUTHEAST TEXAS...BUT ARE MOVING TO THE EAST AND NORTHEAST. SOME
LOW CLOUDS WILL OCCUR OVER THE SOUTHEASTERN COUNTIES THIS
MORNING...BUT SHOULD DISSIPATE BEFORE MIDDAY. IN ADDITION...THERE
IS SOME SCATTERED PATCHY OF FOG ASSOCIATED WITH THE LOW CLOUDS IN
SOUTHEAST TEXAS. AT THIS TIME DO NOT HAVE FOG MENTIONED IN THE
GRIDS AS CURRENT THINKING IS THAT MOST OF THE FOG WILL STAY JUST
OUTSIDE OUR AREA...BUT WILL UPDATE IF THE FOG BECOMES MORE
WIDESPREAD. WILL ALSO BE MONITORING FOR FOG DEVELOPMENT NEAR THE
RED RIVER THIS MORNING AS A COLD FRONT APPROACHES AND THE WINDS
BECOME LIGHT.

THE COLD FRONT HAS NOW PUSHED INTO SOUTHERN OKLAHOMA WITH
TEMPERATURES IN THE 30S AND 40S BEHIND THE FRONT. THIS FRONT WILL
EDGE JUST SOUTH OF THE RED RIVER TODAY...RESULTING IN MUCH COOLER
TEMPERATURES ACROSS OUR NORTHERN COUNTIES. HIGH TEMPERATURES THIS
AFTERNOON WILL RANGE FROM THE UPPER 50S ALONG THE RED RIVER TO
NEAR 80 DEGREES IN OUR SOUTHWESTERN COUNTIES. HIGH CLOUDS ACROSS
THE REGION AND SOME LOWER LEVEL CLOUDS DEVELOPING BEHIND PARTS OF
THE FRONT WILL KEEP TEMPERATURES ON THE COOLER SIDE OF GUIDANCE
TODAY. YESTERDAY...IT APPEARED THAT THE FRONT WOULD STALL OR EVEN
RETREAT A LITTLE NEAR THE RED RIVER TONIGHT. HOWEVER...HI-RES
GUIDANCE INCLUDING THE RAP AND TEXAS TECH WRF ALL SUPPORT THE NAM
WHICH BEGINS TO PUSH THE FRONT SOUTH TONIGHT. WITH THE COLD
TEMPERATURES THAT ARE ALREADY OCCURRING BEHIND THE FRONT...THIS
SOLUTION IS THE MOST PLAUSIBLE ONE AND WILL SHOW THE FRONT SLOWLY
MOVING SOUTH AFTER SUNSET. THE FRONT WILL CONTINUE MOVING SOUTH ON
FRIDAY...HAVING MADE ITS WAY ALMOST ENTIRELY THROUGH THE CWA BY
MIDDAY. TEMPERATURES TONIGHT WILL AGAIN BE VARIABLE WITH OVERNIGHT
LOWS BEHIND THE FRONT IN THE 30S AND LOWER 40S...BUT UP TO THE
UPPER 50S AHEAD OF THE FRONT. THERE IS STILL A LOW CHANCE FOR
DRIZZLE OR VERY LIGHT RAIN OVER THE FAR NORTHEASTERN COUNTIES
TONIGHT.

FRIDAY THROUGH SATURDAY WILL CONTINUE TO BE COOL BEHIND THE FRONT.
WENT WITH THE COOLER GUIDANCE ON SATURDAY ANTICIPATING MOSTLY
CLOUDY SKIES AND POSSIBLY SOME ADDITIONAL LIGHT RAIN. THIS CHANCE
FOR LIGHT RAIN WILL BE ASSOCIATED WITH A WEAK SHORTWAVE LIFTING
NORTHEAST ACROSS THE SOUTHWEST CONUS AND INTO THE PLAINS. THE
TRACK OF THIS SHORTWAVE IS SLIGHTLY FARTHER NORTH TONIGHT WITH THE
BEST CHANCES FOR RAIN NORTH OF THE REGION. THEREFORE REDUCED POPS
TO ONLY 20 PERCENT OF LIGHT RAIN...AND REMOVED THE POPS FROM
SUNDAY AS THE SHORTWAVE WILL BE CROSSING OUT OF THE PLAINS BY
THEN. AGAIN...ANY PRECIPITATION ON SATURDAY MAY LIKELY ONLY BE
DRIZZLE INDUCED BY SOME ISENTROPIC LIFT OVER THE COOL SURFACE
LAYER. AFTER SATURDAY...SOUTH TO SOUTHWEST FLOW IN THE LOW TO MID
LEVELS OF THE ATMOSPHERE WILL RESULT IN ANOTHER WARM UP. WE WILL
SEE TEMPERATURES BACK THE 70S BY MONDAY...WITH BREEZY WINDS AND
MOSTLY CLOUDY SKIES.

BOTH THE GFS AND ECMWF CONTINUE TO ADVERTISE A STRONGER UPPER
LEVEL TROUGH MOVING THROUGH THE PLAINS AROUND THE MIDDLE OF NEXT
WEEK...BUT THE LATEST ECMWF SOLUTION HAS CHANGED FROM THE PAST FEW
RUNS WITH THE TROUGH NOW FARTHER NORTH AND MUCH BROADER.
HOWEVER...IT STILL LOOKS LIKE NORTH AND CENTRAL TEXAS WILL HAVE A
CHANCE FOR SHOWERS AND THUNDERSTORMS ON TUESDAY AS A DRYLINE AND
COLD FRONT MOVE THROUGH THE REGION. SIDED WITH THE ECMWF IN THE
EXTENDED BY CLEARING THE RAIN OUT WITH THE FRONT ON TUESDAY. THE
REMAINDER OF THE FORECAST LOOKS DRY AS WE TRANSITION TO NORTHWEST
AND/OR MORE ZONAL FLOW FOR A FEW DAYS.

82/JLD



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  78  42  56  41  55 /   5  10   5   5  20
WACO, TX              80  53  62  44  62 /  10  10  10  10  20
PARIS, TX             59  39  53  35  53 /  10  20  10   5  20
DENTON, TX            72  40  53  38  53 /   5  10   5   5  20
MCKINNEY, TX          74  40  54  39  53 /  10  10   5   5  20
DALLAS, TX            78  43  57  42  55 /   5  10   5   5  20
TERRELL, TX           76  46  57  41  55 /  10  10  10   5  20
CORSICANA, TX         77  52  61  43  58 /  10  10  10  10  20
TEMPLE, TX            79  54  65  46  64 /  10   5  10  10  20
MINERAL WELLS, TX     74  39  56  39  54 /   5   5   0   5  20

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

 /





AREA FORECAST DISCUSSION...UPDATED

NWS FORT WORTH TX

 1054 AM CST THU JAN 24 2013

.UPDATE...
THE DENSE FOG ADVISORY WAS ALLOWED TO EXPIRE AT 10 AM. PATCHY FOG
PERSISTS IN A FEW OF THE EASTERN AND NORTHERN AREAS...BUT
VISIBILITIES WILL CONTINUE TO IMPROVE LATE THIS MORNING.

THE COLD FRONT WAS LOCATED VERY CLOSE TO THE RED RIVER ON THE 16Z
ANALYSIS AND HAS SHOWN A VERY SLOW SOUTHWARD PROGRESSION. THE
FRONT IS EXPECTED TO CONTINUE A SLOW SOUTHWARD PUSH AS PER OUR
CURRENT FORECAST. THE TIGHT TEMPERATURE GRADIENT NEAR THE FRONT
WILL PLAY HAVOC WITH THE TEMPERATURE FORECAST TODAY AND TONIGHT.
EXPECT TEMPERATURES TO REMAIN OR FALL INTO THE UPPER 50S NORTH OF
THE FRONT...WITH TEMPERATURES SOARING WELL INTO THE 70S IN MOST
AREAS SOUTH OF THE FRONT.

MORNING SOUNDING HERE IN FORT WORTH SUGGESTS THAT TEMPERATURES
WILL LIKELY RISE SLIGHTLY ABOVE THE PREVIOUS FORECAST HIGH
TEMPERATURES IN AREAS SOUTH OF THE SLOWLY ADVANCING COLD FRONT. WE
EXPECT AREAS THAT WILL RECEIVE NEARLY FULL SUN THIS AFTERNOON WILL
APPROACH 80F AS WINDS TEND TO VEER TO SOUTHWEST OR WEST AHEAD OF
THE FRONT. THE RECORD HIGH AT DFW TODAY IS 82...AND THE RECORD
HIGH AT WACO IS 83. THE CURRENT FORECASTS FOR THIS AFTERNOON AT
DFW /79F/ AND AT WACO /80F/ WILL FALL A FEW DEGREES SHORT OF THE
RECORD HIGHS.

IN THE EASTERN ZONES...GENERALLY EAST OF A LINE FROM
MCKINNEY TO HEARNE...THE LOW CLOUDS WILL HOLD HIGH TEMPERATURES
DOWN INTO THE UPPER 60S AND LOWER 70S. AND TEMPERATURES IN THE
COUNTIES ALONG THE RED RIVER WILL BE DEPENDENT ON THE EXACT
POSITION OF THE FRONT AS DISCUSSED ABOVE.

NO CHANGES TO LATER PERIODS OF FORECAST AT THIS TIME.

09/GP

&&

.AVIATION...
METROPLEX...
WIDESPREAD FOG WITH VISIBILITIES OF LESS THAN 1 MILE SHOULD BE
MAINLY NORTH AND EAST OF THE METROPLEX TAF SITES THIS MORNING.
HAVE PLACED 6SM BR...BUT BE AWARE THAT SOME BRIEF GROUND FOG MAY
QUICKLY DROP VISIBILITIES TO 1SM OR LESS BETWEEN 13-16Z.
SOUTHERLY WINDS SHOULD INCREASE TO AROUND 10 KNOTS BY 16Z WHICH
SHOULD DISPERSE ANY REMAINING FOG. A COLD FRONT THAT EXTENDS
SOUTH OF A MCALESTER OKLAHOMA /KMLC/ TO WICHITA FALLS /KSPS/ TO
PLAINVIEW /KPVW/ LINE AT 6 AM WILL MOVE INTO THE METROPLEX TAF
SITES BETWEEN 01 AND 03Z. HAVE INDICATED 36007KT AT 03Z IN THE
METROPLEX TAFS. AS MOISTURE IS LIFTED ABOVE THE FRONT...SOME MVFR
STRATUS MAY DEVELOP BY 08Z.

WACO...IFR CONDITIONS ARE EXPECTED IN THE WACO AREA THROUGH 16Z.
AREAS OF FOG AND MAYBE LOW CLOUDS WILL AFFECT THE WACO AREA THIS
MORNING. VISIBILITIES MAY BRIEFLY FALL TO 1/4 MILE OR LESS...BUT
SHOULD MAINLY BE 1/2 MILE OR GREATER. VFR CONDITIONS SHOULD
RETURN BETWEEN 16 AND 17Z. A COLD FRONT IS EXPECTED TO APPROACH
WACO 09-10Z FRIDAY...SO HAVE PLACED A WIND SHIFT TO 32006KT AT
09Z.

58


&&


.PREV UPDATE...
.UPDATE...
DESPITE WINDS OF 5 TO 10 MPH...THE FOG HAS BECOME MORE WIDESPREAD
THIS MORNING AND WILL UPDATE TO INCLUDE FOG THROUGH THE MID
MORNING HOURS. AREAS ALONG THE RED RIVER ARE REPORTING DENSE FOG
WHERE THE WINDS HAVE BECOME LIGHT. ELSEWHERE...DENSE FOG IS BEING
REPORTED IN ISOLATED AREAS ACROSS THE EASTERN COUNTIES...EAST OF
THE HWY 75/I-45 CORRIDORS. WILL ISSUE A DENSE FOG ADVISORY FOR
THESE TWO AREAS.

82/JLD

&&


.PREV DISCUSSION... /ISSUED 339 AM CST THU JAN 24 2013/
UPPER LEVEL RIDGE IS NOW CENTERED SOUTHWEST OF THE AREA WITH HIGH
CLOUDS STREAMING OVER THE TOP OF THE RIDGE AND INTO THE STATE. AT
THE SURFACE...SOME STRATUS CLOUDS ARE NOW DEVELOPING ACROSS
SOUTHEAST TEXAS...BUT ARE MOVING TO THE EAST AND NORTHEAST. SOME
LOW CLOUDS WILL OCCUR OVER THE SOUTHEASTERN COUNTIES THIS
MORNING...BUT SHOULD DISSIPATE BEFORE MIDDAY. IN ADDITION...THERE
IS SOME SCATTERED PATCHY OF FOG ASSOCIATED WITH THE LOW CLOUDS IN
SOUTHEAST TEXAS. AT THIS TIME DO NOT HAVE FOG MENTIONED IN THE
GRIDS AS CURRENT THINKING IS THAT MOST OF THE FOG WILL STAY JUST
OUTSIDE OUR AREA...BUT WILL UPDATE IF THE FOG BECOMES MORE
WIDESPREAD. WILL ALSO BE MONITORING FOR FOG DEVELOPMENT NEAR THE
RED RIVER THIS MORNING AS A COLD FRONT APPROACHES AND THE WINDS
BECOME LIGHT.

THE COLD FRONT HAS NOW PUSHED INTO SOUTHERN OKLAHOMA WITH
TEMPERATURES IN THE 30S AND 40S BEHIND THE FRONT. THIS FRONT WILL
EDGE JUST SOUTH OF THE RED RIVER TODAY...RESULTING IN MUCH COOLER
TEMPERATURES ACROSS OUR NORTHERN COUNTIES. HIGH TEMPERATURES THIS
AFTERNOON WILL RANGE FROM THE UPPER 50S ALONG THE RED RIVER TO
NEAR 80 DEGREES IN OUR SOUTHWESTERN COUNTIES. HIGH CLOUDS ACROSS
THE REGION AND SOME LOWER LEVEL CLOUDS DEVELOPING BEHIND PARTS OF
THE FRONT WILL KEEP TEMPERATURES ON THE COOLER SIDE OF GUIDANCE
TODAY. YESTERDAY...IT APPEARED THAT THE FRONT WOULD STALL OR EVEN
RETREAT A LITTLE NEAR THE RED RIVER TONIGHT. HOWEVER...HI-RES
GUIDANCE INCLUDING THE RAP AND TEXAS TECH WRF ALL SUPPORT THE NAM
WHICH BEGINS TO PUSH THE FRONT SOUTH TONIGHT. WITH THE COLD
TEMPERATURES THAT ARE ALREADY OCCURRING BEHIND THE FRONT...THIS
SOLUTION IS THE MOST PLAUSIBLE ONE AND WILL SHOW THE FRONT SLOWLY
MOVING SOUTH AFTER SUNSET. THE FRONT WILL CONTINUE MOVING SOUTH ON
FRIDAY...HAVING MADE ITS WAY ALMOST ENTIRELY THROUGH THE CWA BY
MIDDAY. TEMPERATURES TONIGHT WILL AGAIN BE VARIABLE WITH OVERNIGHT
LOWS BEHIND THE FRONT IN THE 30S AND LOWER 40S...BUT UP TO THE
UPPER 50S AHEAD OF THE FRONT. THERE IS STILL A LOW CHANCE FOR
DRIZZLE OR VERY LIGHT RAIN OVER THE FAR NORTHEASTERN COUNTIES
TONIGHT.

FRIDAY THROUGH SATURDAY WILL CONTINUE TO BE COOL BEHIND THE FRONT.
WENT WITH THE COOLER GUIDANCE ON SATURDAY ANTICIPATING MOSTLY
CLOUDY SKIES AND POSSIBLY SOME ADDITIONAL LIGHT RAIN. THIS CHANCE
FOR LIGHT RAIN WILL BE ASSOCIATED WITH A WEAK SHORTWAVE LIFTING
NORTHEAST ACROSS THE SOUTHWEST CONUS AND INTO THE PLAINS. THE
TRACK OF THIS SHORTWAVE IS SLIGHTLY FARTHER NORTH TONIGHT WITH THE
BEST CHANCES FOR RAIN NORTH OF THE REGION. THEREFORE REDUCED POPS
TO ONLY 20 PERCENT OF LIGHT RAIN...AND REMOVED THE POPS FROM
SUNDAY AS THE SHORTWAVE WILL BE CROSSING OUT OF THE PLAINS BY
THEN. AGAIN...ANY PRECIPITATION ON SATURDAY MAY LIKELY ONLY BE
DRIZZLE INDUCED BY SOME ISENTROPIC LIFT OVER THE COOL SURFACE
LAYER. AFTER SATURDAY...SOUTH TO SOUTHWEST FLOW IN THE LOW TO MID
LEVELS OF THE ATMOSPHERE WILL RESULT IN ANOTHER WARM UP. WE WILL
SEE TEMPERATURES BACK THE 70S BY MONDAY...WITH BREEZY WINDS AND
MOSTLY CLOUDY SKIES.

BOTH THE GFS AND ECMWF CONTINUE TO ADVERTISE A STRONGER UPPER
LEVEL TROUGH MOVING THROUGH THE PLAINS AROUND THE MIDDLE OF NEXT
WEEK...BUT THE LATEST ECMWF SOLUTION HAS CHANGED FROM THE PAST FEW
RUNS WITH THE TROUGH NOW FARTHER NORTH AND MUCH BROADER.
HOWEVER...IT STILL LOOKS LIKE NORTH AND CENTRAL TEXAS WILL HAVE A
CHANCE FOR SHOWERS AND THUNDERSTORMS ON TUESDAY AS A DRYLINE AND
COLD FRONT MOVE THROUGH THE REGION. SIDED WITH THE ECMWF IN THE
EXTENDED BY CLEARING THE RAIN OUT WITH THE FRONT ON TUESDAY. THE
REMAINDER OF THE FORECAST LOOKS DRY AS WE TRANSITION TO NORTHWEST
AND/OR MORE ZONAL FLOW FOR A FEW DAYS.

82/JLD



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  79  42  56  41  55 /   5  10   5   5  20
WACO, TX              80  53  62  44  62 /  10  10  10  10  20
PARIS, TX             59  39  53  35  53 /  10  20  10   5  20
DENTON, TX            72  40  53  38  53 /   5  10   5   5  20
MCKINNEY, TX          74  40  54  39  53 /  10  10   5   5  20
DALLAS, TX            78  43  57  42  55 /   5  10   5   5  20
TERRELL, TX           76  46  57  41  55 /  10  10  10   5  20
CORSICANA, TX         77  52  61  43  58 /  10  10  10  10  20
TEMPLE, TX            79  54  65  46  64 /  10   5  10  10  20
MINERAL WELLS, TX     74  39  56  39  54 /   5   5   0   5  20

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$








AREA FORECAST DISCUSSION...UPDATED

NWS FORT WORTH TX

 657 AM CST THU JAN 24 2013

.AVIATION...
METROPLEX...
WIDESPREAD FOG WITH VISIBILITIES OF LESS THAN 1 MILE SHOULD BE
MAINLY NORTH AND EAST OF THE METROPLEX TAF SITES THIS MORNING.
HAVE PLACED 6SM BR...BUT BE AWARE THAT SOME BRIEF GROUND FOG MAY
QUICKLY DROP VISIBILITIES TO 1SM OR LESS BETWEEN 13-16Z.
SOUTHERLY WINDS SHOULD INCREASE TO AROUND 10 KNOTS BY 16Z WHICH
SHOULD DISPERSE ANY REMAINING FOG. A COLD FRONT THAT EXTNEDS
SOUTH OF A MCALESTER OKLAHOMA /KMLC/ TO WICHITA FALLS /KSPS/ TO
PLAINVIEW /KPVW/ LINE AT 6 AM WILL MOVE INTO THE METROPLEX TAF
SITES BETWEEN 01 AND 03Z. HAVE INDICATED 36007KT AT 03Z IN THE
METROPLEX TAFS. AS MOISTURE IS LIFTED ABOVE THE FRONT...SOME MVFR
STRATUS MAY DEVELOP BY 08Z.


WACO...IFR CONDITIONS ARE EXPECTED IN THE WACO AREA THROUGH 16Z.
AREAS OF FOG AND MAYBE LOW CLOUDS WILL AFFECT THE WACO AREA THIS
MORNING. VISIBILITIES MAY BRIEFLY FALL TO 1/4 MILE OR LESS...BUT
SHOULD MAINLY BE 1/2 MILE OR GREATER. VFR CONDITIONS SHOULD
RETURN BETWEEN 16 AND 17Z. A COLD FRONT IS EXPECTED TO APPROACH
WACO 09-10Z FRIDAY...SO HAVE PLACED A WIND SHIFT TO 32006KT AT
09Z.

58

&&

.UPDATE...
DESPITE WINDS OF 5 TO 10 MPH...THE FOG HAS BECOME MORE WIDESPREAD
THIS MORNING AND WILL UPDATE TO INCLUDE FOG THROUGH THE MID
MORNING HOURS. AREAS ALONG THE RED RIVER ARE REPORTING DENSE FOG
WHERE THE WINDS HAVE BECOME LIGHT. ELSEWHERE...DENSE FOG IS BEING
REPORTED IN ISOLATED AREAS ACROSS THE EASTERN COUNTIES...EAST OF
THE HWY 75/I-45 CORRIDORS. WILL ISSUE A DENSE FOG ADVISORY FOR
THESE TWO AREAS.

82/JLD

&&

.PREV DISCUSSION... /ISSUED 339 AM CST THU JAN 24 2013/
UPPER LEVEL RIDGE IS NOW CENTERED SOUTHWEST OF THE AREA WITH HIGH
CLOUDS STREAMING OVER THE TOP OF THE RIDGE AND INTO THE STATE. AT
THE SURFACE...SOME STRATUS CLOUDS ARE NOW DEVELOPING ACROSS
SOUTHEAST TEXAS...BUT ARE MOVING TO THE EAST AND NORTHEAST. SOME
LOW CLOUDS WILL OCCUR OVER THE SOUTHEASTERN COUNTIES THIS
MORNING...BUT SHOULD DISSIPATE BEFORE MIDDAY. IN ADDITION...THERE
IS SOME SCATTERED PATCHY OF FOG ASSOCIATED WITH THE LOW CLOUDS IN
SOUTHEAST TEXAS. AT THIS TIME DO NOT HAVE FOG MENTIONED IN THE
GRIDS AS CURRENT THINKING IS THAT MOST OF THE FOG WILL STAY JUST
OUTSIDE OUR AREA...BUT WILL UPDATE IF THE FOG BECOMES MORE
WIDESPREAD. WILL ALSO BE MONITORING FOR FOG DEVELOPMENT NEAR THE
RED RIVER THIS MORNING AS A COLD FRONT APPROACHES AND THE WINDS
BECOME LIGHT.

THE COLD FRONT HAS NOW PUSHED INTO SOUTHERN OKLAHOMA WITH
TEMPERATURES IN THE 30S AND 40S BEHIND THE FRONT. THIS FRONT WILL
EDGE JUST SOUTH OF THE RED RIVER TODAY...RESULTING IN MUCH COOLER
TEMPERATURES ACROSS OUR NORTHERN COUNTIES. HIGH TEMPERATURES THIS
AFTERNOON WILL RANGE FROM THE UPPER 50S ALONG THE RED RIVER TO
NEAR 80 DEGREES IN OUR SOUTHWESTERN COUNTIES. HIGH CLOUDS ACROSS
THE REGION AND SOME LOWER LEVEL CLOUDS DEVELOPING BEHIND PARTS OF
THE FRONT WILL KEEP TEMPERATURES ON THE COOLER SIDE OF GUIDANCE
TODAY. YESTERDAY...IT APPEARED THAT THE FRONT WOULD STALL OR EVEN
RETREAT A LITTLE NEAR THE RED RIVER TONIGHT. HOWEVER...HI-RES
GUIDANCE INCLUDING THE RAP AND TEXAS TECH WRF ALL SUPPORT THE NAM
WHICH BEGINS TO PUSH THE FRONT SOUTH TONIGHT. WITH THE COLD
TEMPERATURES THAT ARE ALREADY OCCURRING BEHIND THE FRONT...THIS
SOLUTION IS THE MOST PLAUSIBLE ONE AND WILL SHOW THE FRONT SLOWLY
MOVING SOUTH AFTER SUNSET. THE FRONT WILL CONTINUE MOVING SOUTH ON
FRIDAY...HAVING MADE ITS WAY ALMOST ENTIRELY THROUGH THE CWA BY
MIDDAY. TEMPERATURES TONIGHT WILL AGAIN BE VARIABLE WITH OVERNIGHT
LOWS BEHIND THE FRONT IN THE 30S AND LOWER 40S...BUT UP TO THE
UPPER 50S AHEAD OF THE FRONT. THERE IS STILL A LOW CHANCE FOR
DRIZZLE OR VERY LIGHT RAIN OVER THE FAR NORTHEASTERN COUNTIES
TONIGHT.

FRIDAY THROUGH SATURDAY WILL CONTINUE TO BE COOL BEHIND THE FRONT.
WENT WITH THE COOLER GUIDANCE ON SATURDAY ANTICIPATING MOSTLY
CLOUDY SKIES AND POSSIBLY SOME ADDITIONAL LIGHT RAIN. THIS CHANCE
FOR LIGHT RAIN WILL BE ASSOCIATED WITH A WEAK SHORTWAVE LIFTING
NORTHEAST ACROSS THE SOUTHWEST CONUS AND INTO THE PLAINS. THE
TRACK OF THIS SHORTWAVE IS SLIGHTLY FARTHER NORTH TONIGHT WITH THE
BEST CHANCES FOR RAIN NORTH OF THE REGION. THEREFORE REDUCED POPS
TO ONLY 20 PERCENT OF LIGHT RAIN...AND REMOVED THE POPS FROM
SUNDAY AS THE SHORTWAVE WILL BE CROSSING OUT OF THE PLAINS BY
THEN. AGAIN...ANY PRECIPITATION ON SATURDAY MAY LIKELY ONLY BE
DRIZZLE INDUCED BY SOME ISENTROPIC LIFT OVER THE COOL SURFACE
LAYER. AFTER SATURDAY...SOUTH TO SOUTHWEST FLOW IN THE LOW TO MID
LEVELS OF THE ATMOSPHERE WILL RESULT IN ANOTHER WARM UP. WE WILL
SEE TEMPERATURES BACK THE 70S BY MONDAY...WITH BREEZY WINDS AND
MOSTLY CLOUDY SKIES.

BOTH THE GFS AND ECMWF CONTINUE TO ADVERTISE A STRONGER UPPER
LEVEL TROUGH MOVING THROUGH THE PLAINS AROUND THE MIDDLE OF NEXT
WEEK...BUT THE LATEST ECMWF SOLUTION HAS CHANGED FROM THE PAST FEW
RUNS WITH THE TROUGH NOW FARTHER NORTH AND MUCH BROADER.
HOWEVER...IT STILL LOOKS LIKE NORTH AND CENTRAL TEXAS WILL HAVE A
CHANCE FOR SHOWERS AND THUNDERSTORMS ON TUESDAY AS A DRYLINE AND
COLD FRONT MOVE THROUGH THE REGION. SIDED WITH THE ECMWF IN THE
EXTENDED BY CLEARING THE RAIN OUT WITH THE FRONT ON TUESDAY. THE
REMAINDER OF THE FORECAST LOOKS DRY AS WE TRANSITION TO NORTHWEST
AND/OR MORE ZONAL FLOW FOR A FEW DAYS.

82/JLD



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  75  42  56  41  55 /   5  10   5   5  20
WACO, TX              79  53  62  44  62 /  10  10  10  10  20
PARIS, TX             56  39  53  35  53 /  10  20  10   5  20
DENTON, TX            72  40  53  38  53 /   5  10   5   5  20
MCKINNEY, TX          72  40  54  39  53 /  10  10   5   5  20
DALLAS, TX            75  43  57  42  55 /   5  10   5   5  20
TERRELL, TX           74  46  57  41  55 /  10  10  10   5  20
CORSICANA, TX         75  52  61  43  58 /  10  10  10  10  20
TEMPLE, TX            79  54  65  46  64 /  10   5  10  10  20
MINERAL WELLS, TX     73  39  56  39  54 /   5   5   0   5  20

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR TXZ091>095-
102>107-121>123-135-148.


&&

$$

58/82








AREA FORECAST DISCUSSION...UPDATED

NWS FORT WORTH TX

 604 AM CST THU JAN 24 2013

.UPDATE...
DESPITE WINDS OF 5 TO 10 MPH...THE FOG HAS BECOME MORE WIDESPREAD
THIS MORNING AND WILL UPDATE TO INCLUDE FOG THROUGH THE MID
MORNING HOURS. AREAS ALONG THE RED RIVER ARE REPORTING DENSE FOG
WHERE THE WINDS HAVE BECOME LIGHT. ELSEWHERE...DENSE FOG IS BEING
REPORTED IN ISOLATED AREAS ACROSS THE EASTERN COUNTIES...EAST OF
THE HWY 75/I-45 CORRIDORS. WILL ISSUE A DENSE FOG ADVISORY FOR
THESE TWO AREAS.

82/JLD

&&

.PREV DISCUSSION... /ISSUED 339 AM CST THU JAN 24 2013/
UPPER LEVEL RIDGE IS NOW CENTERED SOUTHWEST OF THE AREA WITH HIGH
CLOUDS STREAMING OVER THE TOP OF THE RIDGE AND INTO THE STATE. AT
THE SURFACE...SOME STRATUS CLOUDS ARE NOW DEVELOPING ACROSS
SOUTHEAST TEXAS...BUT ARE MOVING TO THE EAST AND NORTHEAST. SOME
LOW CLOUDS WILL OCCUR OVER THE SOUTHEASTERN COUNTIES THIS
MORNING...BUT SHOULD DISSIPATE BEFORE MIDDAY. IN ADDITION...THERE
IS SOME SCATTERED PATCHY OF FOG ASSOCIATED WITH THE LOW CLOUDS IN
SOUTHEAST TEXAS. AT THIS TIME DO NOT HAVE FOG MENTIONED IN THE
GRIDS AS CURRENT THINKING IS THAT MOST OF THE FOG WILL STAY JUST
OUTSIDE OUR AREA...BUT WILL UPDATE IF THE FOG BECOMES MORE
WIDESPREAD. WILL ALSO BE MONITORING FOR FOG DEVELOPMENT NEAR THE
RED RIVER THIS MORNING AS A COLD FRONT APPROACHES AND THE WINDS
BECOME LIGHT.

THE COLD FRONT HAS NOW PUSHED INTO SOUTHERN OKLAHOMA WITH
TEMPERATURES IN THE 30S AND 40S BEHIND THE FRONT. THIS FRONT WILL
EDGE JUST SOUTH OF THE RED RIVER TODAY...RESULTING IN MUCH COOLER
TEMPERATURES ACROSS OUR NORTHERN COUNTIES. HIGH TEMPERATURES THIS
AFTERNOON WILL RANGE FROM THE UPPER 50S ALONG THE RED RIVER TO
NEAR 80 DEGREES IN OUR SOUTHWESTERN COUNTIES. HIGH CLOUDS ACROSS
THE REGION AND SOME LOWER LEVEL CLOUDS DEVELOPING BEHIND PARTS OF
THE FRONT WILL KEEP TEMPERATURES ON THE COOLER SIDE OF GUIDANCE
TODAY. YESTERDAY...IT APPEARED THAT THE FRONT WOULD STALL OR EVEN
RETREAT A LITTLE NEAR THE RED RIVER TONIGHT. HOWEVER...HI-RES
GUIDANCE INCLUDING THE RAP AND TEXAS TECH WRF ALL SUPPORT THE NAM
WHICH BEGINS TO PUSH THE FRONT SOUTH TONIGHT. WITH THE COLD
TEMPERATURES THAT ARE ALREADY OCCURRING BEHIND THE FRONT...THIS
SOLUTION IS THE MOST PLAUSIBLE ONE AND WILL SHOW THE FRONT SLOWLY
MOVING SOUTH AFTER SUNSET. THE FRONT WILL CONTINUE MOVING SOUTH ON
FRIDAY...HAVING MADE ITS WAY ALMOST ENTIRELY THROUGH THE CWA BY
MIDDAY. TEMPERATURES TONIGHT WILL AGAIN BE VARIABLE WITH OVERNIGHT
LOWS BEHIND THE FRONT IN THE 30S AND LOWER 40S...BUT UP TO THE
UPPER 50S AHEAD OF THE FRONT. THERE IS STILL A LOW CHANCE FOR
DRIZZLE OR VERY LIGHT RAIN OVER THE FAR NORTHEASTERN COUNTIES
TONIGHT.

FRIDAY THROUGH SATURDAY WILL CONTINUE TO BE COOL BEHIND THE FRONT.
WENT WITH THE COOLER GUIDANCE ON SATURDAY ANTICIPATING MOSTLY
CLOUDY SKIES AND POSSIBLY SOME ADDITIONAL LIGHT RAIN. THIS CHANCE
FOR LIGHT RAIN WILL BE ASSOCIATED WITH A WEAK SHORTWAVE LIFTING
NORTHEAST ACROSS THE SOUTHWEST CONUS AND INTO THE PLAINS. THE
TRACK OF THIS SHORTWAVE IS SLIGHTLY FARTHER NORTH TONIGHT WITH THE
BEST CHANCES FOR RAIN NORTH OF THE REGION. THEREFORE REDUCED POPS
TO ONLY 20 PERCENT OF LIGHT RAIN...AND REMOVED THE POPS FROM
SUNDAY AS THE SHORTWAVE WILL BE CROSSING OUT OF THE PLAINS BY
THEN. AGAIN...ANY PRECIPITATION ON SATURDAY MAY LIKELY ONLY BE
DRIZZLE INDUCED BY SOME ISENTROPIC LIFT OVER THE COOL SURFACE
LAYER. AFTER SATURDAY...SOUTH TO SOUTHWEST FLOW IN THE LOW TO MID
LEVELS OF THE ATMOSPHERE WILL RESULT IN ANOTHER WARM UP. WE WILL
SEE TEMPERATURES BACK THE 70S BY MONDAY...WITH BREEZY WINDS AND
MOSTLY CLOUDY SKIES.

BOTH THE GFS AND ECMWF CONTINUE TO ADVERTISE A STRONGER UPPER
LEVEL TROUGH MOVING THROUGH THE PLAINS AROUND THE MIDDLE OF NEXT
WEEK...BUT THE LATEST ECMWF SOLUTION HAS CHANGED FROM THE PAST FEW
RUNS WITH THE TROUGH NOW FARTHER NORTH AND MUCH BROADER.
HOWEVER...IT STILL LOOKS LIKE NORTH AND CENTRAL TEXAS WILL HAVE A
CHANCE FOR SHOWERS AND THUNDERSTORMS ON TUESDAY AS A DRYLINE AND
COLD FRONT MOVE THROUGH THE REGION. SIDED WITH THE ECMWF IN THE
EXTENDED BY CLEARING THE RAIN OUT WITH THE FRONT ON TUESDAY. THE
REMAINDER OF THE FORECAST LOOKS DRY AS WE TRANSITION TO NORTHWEST
AND/OR MORE ZONAL FLOW FOR A FEW DAYS.

82/JLD

&&



.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  75  42  56  41  55 /   5  10   5   5  20
WACO, TX              79  53  62  44  62 /  10  10  10  10  20
PARIS, TX             56  39  53  35  53 /  10  20  10   5  20
DENTON, TX            72  40  53  38  53 /   5  10   5   5  20
MCKINNEY, TX          72  40  54  39  53 /  10  10   5   5  20
DALLAS, TX            75  43  57  42  55 /   5  10   5   5  20
TERRELL, TX           74  46  57  41  55 /  10  10  10   5  20
CORSICANA, TX         75  52  61  43  58 /  10  10  10  10  20
TEMPLE, TX            79  54  65  46  64 /  10   5  10  10  20
MINERAL WELLS, TX     73  39  56  39  54 /   5   5   0   5  20

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR TXZ091>095-
102>107-121>123-135-148.


&&

$$

58/82






AREA FORECAST DISCUSSION

NWS FORT WORTH TX

 339 AM CST THU JAN 24 2013

.DISCUSSION...
UPPER LEVEL RIDGE IS NOW CENTERED SOUTHWEST OF THE AREA WITH HIGH
CLOUDS STREAMING OVER THE TOP OF THE RIDGE AND INTO THE STATE. AT
THE SURFACE...SOME STRATUS CLOUDS ARE NOW DEVELOPING ACROSS
SOUTHEAST TEXAS...BUT ARE MOVING TO THE EAST AND NORTHEAST. SOME
LOW CLOUDS WILL OCCUR OVER THE SOUTHEASTERN COUNTIES THIS
MORNING...BUT SHOULD DISSIPATE BEFORE MIDDAY. IN ADDITION...THERE
IS SOME SCATTERED PATCHY OF FOG ASSOCIATED WITH THE LOW CLOUDS IN
SOUTHEAST TEXAS. AT THIS TIME DO NOT HAVE FOG MENTIONED IN THE
GRIDS AS CURRENT THINKING IS THAT MOST OF THE FOG WILL STAY JUST
OUTSIDE OUR AREA...BUT WILL UPDATE IF THE FOG BECOMES MORE
WIDESPREAD. WILL ALSO BE MONITORING FOR FOG DEVELOPMENT NEAR THE
RED RIVER THIS MORNING AS A COLD FRONT APPROACHES AND THE WINDS
BECOME LIGHT.

THE COLD FRONT HAS NOW PUSHED INTO SOUTHERN OKLAHOMA WITH
TEMPERATURES IN THE 30S AND 40S BEHIND THE FRONT. THIS FRONT WILL
EDGE JUST SOUTH OF THE RED RIVER TODAY...RESULTING IN MUCH COOLER
TEMPERATURES ACROSS OUR NORTHERN COUNTIES. HIGH TEMPERATURES THIS
AFTERNOON WILL RANGE FROM THE UPPER 50S ALONG THE RED RIVER TO
NEAR 80 DEGREES IN OUR SOUTHWESTERN COUNTIES. HIGH CLOUDS ACROSS
THE REGION AND SOME LOWER LEVEL CLOUDS DEVELOPING BEHIND PARTS OF
THE FRONT WILL KEEP TEMPERATURES ON THE COOLER SIDE OF GUIDANCE
TODAY. YESTERDAY...IT APPEARED THAT THE FRONT WOULD STALL OR EVEN
RETREAT A LITTLE NEAR THE RED RIVER TONIGHT. HOWEVER...HI-RES
GUIDANCE INCLUDING THE RAP AND TEXAS TECH WRF ALL SUPPORT THE NAM
WHICH BEGINS TO PUSH THE FRONT SOUTH TONIGHT. WITH THE COLD
TEMPERATURES THAT ARE ALREADY OCCURRING BEHIND THE FRONT...THIS
SOLUTION IS THE MOST PLAUSIBLE ONE AND WILL SHOW THE FRONT SLOWLY
MOVING SOUTH AFTER SUNSET. THE FRONT WILL CONTINUE MOVING SOUTH ON
FRIDAY...HAVING MADE ITS WAY ALMOST ENTIRELY THROUGH THE CWA BY
MIDDAY. TEMPERATURES TONIGHT WILL AGAIN BE VARIABLE WITH OVERNIGHT
LOWS BEHIND THE FRONT IN THE 30S AND LOWER 40S...BUT UP TO THE
UPPER 50S AHEAD OF THE FRONT. THERE IS STILL A LOW CHANCE FOR
DRIZZLE OR VERY LIGHT RAIN OVER THE FAR NORTHEASTERN COUNTIES
TONIGHT.

FRIDAY THROUGH SATURDAY WILL CONTINUE TO BE COOL BEHIND THE FRONT.
WENT WITH THE COOLER GUIDANCE ON SATURDAY ANTICIPATING MOSTLY
CLOUDY SKIES AND POSSIBLY SOME ADDITIONAL LIGHT RAIN. THIS CHANCE
FOR LIGHT RAIN WILL BE ASSOCIATED WITH A WEAK SHORTWAVE LIFTING
NORTHEAST ACROSS THE SOUTHWEST CONUS AND INTO THE PLAINS. THE
TRACK OF THIS SHORTWAVE IS SLIGHTLY FARTHER NORTH TONIGHT WITH THE
BEST CHANCES FOR RAIN NORTH OF THE REGION. THEREFORE REDUCED POPS
TO ONLY 20 PERCENT OF LIGHT RAIN...AND REMOVED THE POPS FROM
SUNDAY AS THE SHORTWAVE WILL BE CROSSING OUT OF THE PLAINS BY
THEN. AGAIN...ANY PRECIPITATION ON SATURDAY MAY LIKELY ONLY BE
DRIZZLE INDUCED BY SOME ISENTROPIC LIFT OVER THE COOL SURFACE
LAYER. AFTER SATURDAY...SOUTH TO SOUTHWEST FLOW IN THE LOW TO MID
LEVELS OF THE ATMOSPHERE WILL RESULT IN ANOTHER WARM UP. WE WILL
SEE TEMPERATURES BACK THE 70S BY MONDAY...WITH BREEZY WINDS AND
MOSTLY CLOUDY SKIES.

BOTH THE GFS AND ECMWF CONTINUE TO ADVERTISE A STRONGER UPPER
LEVEL TROUGH MOVING THROUGH THE PLAINS AROUND THE MIDDLE OF NEXT
WEEK...BUT THE LATEST ECMWF SOLUTION HAS CHANGED FROM THE PAST FEW
RUNS WITH THE TROUGH NOW FARTHER NORTH AND MUCH BROADER.
HOWEVER...IT STILL LOOKS LIKE NORTH AND CENTRAL TEXAS WILL HAVE A
CHANCE FOR SHOWERS AND THUNDERSTORMS ON TUESDAY AS A DRYLINE AND
COLD FRONT MOVE THROUGH THE REGION. SIDED WITH THE ECMWF IN THE
EXTENDED BY CLEARING THE RAIN OUT WITH THE FRONT ON TUESDAY. THE
REMAINDER OF THE FORECAST LOOKS DRY AS WE TRANSITION TO NORTHWEST
AND/OR MORE ZONAL FLOW FOR A FEW DAYS.

82/JLD

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  75  42  56  41  55 /   5  10   5   5  20
WACO, TX              79  53  62  44  62 /  10  10  10  10  20
PARIS, TX             56  39  53  35  53 /  10  20  10   5  20
DENTON, TX            72  40  53  38  53 /   5  10   5   5  20
MCKINNEY, TX          72  40  54  39  53 /  10  10   5   5  20
DALLAS, TX            75  43  57  42  55 /   5  10   5   5  20
TERRELL, TX           74  46  57  41  55 /  10  10  10   5  20
CORSICANA, TX         75  52  61  43  58 /  10  10  10  10  20
TEMPLE, TX            79  54  65  46  64 /  10   5  10  10  20
MINERAL WELLS, TX     73  39  56  39  54 /   5   5   0   5  20

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

58/82






AREA FORECAST DISCUSSION...UPDATED

NWS FORT WORTH TX

 1104 PM CST WED JAN 23 2013

.AVIATION...
HIGH CLOUDS CONTINUE TO STREAM FROM NW TO SE ACROSS NORTH TEXAS
AND SURFACE WINDS REMAIN FROM THE SOUTH AROUND 5 TO 10 KNOTS. THE
MAIN CONCERN OVERNIGHT WILL BE THE POTENTIAL FOR FOG/LOW CLOUDS.
AS THE PREVIOUS DISCUSSION STATED...THE DEPTH OF THE MOISTURE WILL
LIMIT THE THREAT FOR STRATUS. ALSO...SURFACE WINDS OF 5-10 KTS AND
SW WINDS AROUND 20-25 KTS JUST OFF THE SURFACE SHOULD LIMIT THE
THREAT FOR FOG.

LATEST RAP SOUNDINGS INDICATE VERY LITTLE THREAT FOR RESTRICTIONS
OVERNIGHT...WHILE THE NAM CONTINUES TO SHOW POSSIBLE LOW CLOUDS. A
SURFACE FRONT IN OKLAHOMA WILL BE LOCATED NEAR THE RED RIVER BY
DAYBREAK AND THE BEST CHANCES FOR FOG WILL BE LOCATED ALONG THIS
SLOW-MOVING BOUNDARY WHERE WINDS BRIEFLY GO CALM. ADDITIONAL FOG
IS LIKELY ACROSS SOUTHEAST TEXAS WHERE THE BEST MOISTURE AND
LIGHTER SURFACE WINDS ARE LOCATED.

JUST MADE MINOR TWEAKS TO THE PREVIOUS TAFS...AS SIGNIFICANT
CHANGES WERE NOT NEEDED. FOR THE METROPLEX...WILL SHOW 6SM AND
SCT004 TO HINT AT THE POSSIBILITY OF SOMETHING FORMING BY
MORNING...BUT SINCE CONFIDENCE IS LOW IN THIS OUTCOME...DIDNT WANT
TO PREVAIL ANY RESTRICTIONS. MOISTURE LOOKS TO BE A BIT DEEPER
FOR WACO AND WILL CONTINUE THE TEMPO GROUP FROM 11-15Z...BUT
LOWERED THE CEILINGS TO 400 FEET. THE CONFIDENCE IN THIS OUTCOME
IS STILL NOT HIGH. ANY CIGS/VIS RESTRICTIONS SHOULD LIFT AROUND
15Z.

THE FRONTAL TIMING DIFFERS BETWEEN THE GUIDANCE BUT WILL STICK
WITH THE NAM/RAP GROUP WHICH SLOWLY BRINGS THE FRONT THROUGH THE
METROPLEX LATE IN THE EVENING. MVFR CIGS ARE LIKELY BEHIND THE
FRONT.

HAMPSHIRE

&&

.UPDATE...
HAVE AMENDED SKY FORECAST FOR MORE CLOUDS IN THE EAST LATE TONIGHT
AND ACROSS THE NORTH TOMORROW NEAR/BEHIND THE WEAK FRONT.

TR.92

&&

.PREV DISCUSSION... /ISSUED 303 PM CST WED JAN 23 2013/
A WEAK COLD FRONT WILL DROP ACROSS NORTHERN AREAS OF NORTH TEXAS
THURSDAY. THIS WILL PRODUCE LIGHTER WINDS THURSDAY THAN WE HAD
BEEN FORECASTING EARLIER IN THE WEEK...BUT THE ONLY ASSOCIATED
WEATHER WILL BE SOME LIGHT RAIN IN THE NORTHEAST THURSDAY NIGHT.
THE FRONT GETS ANOTHER PUSH ON FRIDAY MORNING AND SWEEPS SOUTH
ACROSS NORTH TEXAS...BUT PRECIP IS EXPECTED TO REMAIN EAST AND
SOUTH OF OUR AREA.

OVER THE WEEKEND...FLOW ALOFT SWITCHES FROM NORTHWEST TO
SOUTHWEST AS A LOW AMPLITUDE RIDGE MOVES EAST...AND A SERIES OF
DISTURBANCES ARE EXPECTED TO PRODUCE INTERVALS OF PRECIPITATION.
ON SATURDAY MORNING SOME LIGHT RAIN/DRIZZLE SHOULD FALL AS
MOISTURE OVERRUNS THE FRONT...AND WEAK LARGE SCALE LIFT FROM THE
UPPER DISTURBANCES ON SUNDAY AND MONDAY WILL PRODUCE AREAS OF
SHOWERS.

AS A STRONGER TROF APPROACHES THE AREA TUESDAY...WIDESPREAD LIFT
INCREASES AND LAPSE RATES STEEPEN. THUNDERSTORMS THEN ENTER THE
EQUATION AS WELL. CAPE IS NOT LOOKING THAT IMPRESSIVE YET...SO THE
SEVERE THREAT CURRENTLY APPEARS FAIRLY MINIMAL. TIMING AND
INTENSITY OF THE UPPER TROF AS WELL AS FROPA ARE NOT YET WELL
HANDLED...BUT PRE HPC AND MY OWN OBSERVATION OVER THE LAST FEW
DAYS THE ECMWF/CMC HAVE HAD BETTER CONTINUITY THAN THE GFS AND I
USED THEIR TIMING FOR THE FROPA AND END OF PRECIP TUESDAY NIGHT. 84



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  52  74  49  55  42 /   0   5  10   5  20
WACO, TX              54  77  54  59  45 /   0  10  10  10  20
PARIS, TX             47  60  43  53  38 /   5  10  20  10  20
DENTON, TX            49  72  45  53  39 /   0   5  10   5  20
MCKINNEY, TX          50  72  46  53  39 /   0  10  10   5  20
DALLAS, TX            55  73  50  55  43 /   0   5  10   5  20
TERRELL, TX           53  72  50  55  42 /   0  10  10  10  20
CORSICANA, TX         54  74  53  58  46 /   0  10  10  10  20
TEMPLE, TX            54  78  55  59  47 /   0  10   5  10  20
MINERAL WELLS, TX     50  68  44  56  39 /   0   5   5   0  20

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

 /






FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION

VISIT...

 HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)





AREA FORECAST DISCUSSION

NWS MILWAUKEE/SULLIVAN WI

 856 PM CST FRI JAN 25 2013

.UPDATE...
SUBSIDENCE FROM THE EXITING MID LEVEL SHORT WAVE...COMBINED WITH
COLD DRY CANADIAN HIGH PRESSURE IS DOING AN EXCELLENT JOB AT
ERODING THE CLOUD DECK THAT WAS WIDESPREAD AT THE START OF THE
EVENING. SNOW SHOWERS/FLURRIES HAVE JUST ABOUT ENDED. LOOK FOR
CONTINUED CLEARING THROUGH THE OVERNIGHT. BOOSTED MIN TEMPS JUST A
NOTCH GIVEN EXPECTED MIXING THROUGH A GOOD PART OF THE NIGHT.
OTHERWISE FEW CHANGES NEEDED.

&&

.AVIATION/06Z TAFS/...
HIGH PRESSURE WILL BRING VFR CONDITIONS THROUGH THE TAF PERIOD.

&&

.PREV DISCUSSION... /ISSUED 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.

&&

$$

UPDATE...DAVIS
TONIGHT/SATURDAY AND AVIATION/MARINE...MRC
SATURDAY NIGHT THROUGH FRIDAY...GEHRING






AREA FORECAST DISCUSSION

NWS GREEN BAY WI

 230 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...ARCTIC HIGH PRESSURE OVERHEAD TODAY WILL LEAD TO GREAT
FLYING CONDITIONS THIS AFTERNOON.  CONDITIONS DETERIORATE THIS
EVENING WHEN A BAND OF SNOW AHEAD OF A LOW PRESSURE SYSTEM DIVES
SOUTHEAST INTO THE NORTHERN HALF OF THE STATE.  AS THE CLOUD DECK
LOWERS...OBSERVATIONS UPSTREAM SUGGEST IFR/LIFR VSBYS/CIGS ARE
POSSIBLE AFTER MIDNIGHT INTO FRIDAY MORNING.  SEVERAL INCHES OF
FLUFFY SNOW IS LIKELY NORTH OF ROUTE 29.  SNOW WILL BE GRADUALLY
DIMINISHING FRIDAY AFTERNOON AND CONDITIONS WILL SLOWLY IMPROVE.

MPC
&&

.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.

&&

$$
MPC/ECKBERG







AREA FORECAST DISCUSSION

NWS GREEN BAY WI

 1022 PM CST WED JAN 23 2013

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.PREV DISCUSSION...ISSUED AT 745 PM CST WED JAN 23 2013...

UPDATE...MUCH AS WITH THE INFLUX OF THE ARCTIC AIR SATURDAY
EVENING...SHSN WOUND UP BEING MORE SIG THAN INITIALLY EXPECTED.
BUT OTHER THAN THE LAKE-EFFECT AFFECTING N-C WI AND SOME LAKE-
EFFECT PUSHING INTO THE NORTHERN DOOR...THE LAST SIG SHSN WAS
EXITING THE FCST AREA OVER SRN LAKE WINNEBAGO. SKIES CLEARING
RAPIDLY IN THE STG SUBSIDENCE BEHIND THE DEPARTING SHRTWV AND IN
THE CAA REGIME AHEAD OF STG ANTICYCLONE HEADING INTO THE RGN.

A FEW REPORTS OF SIG SNOWS RECEIVED FM THE DLH OFFICE FM IRON
COUNTY WI. BUT FLOW ACRS LAKE SUPERIOR IS A BIT TOO NLY TO BE
IDEAL FOR VILAS COUNTY...SO THINK REALLY SIG SNOWS WL REMAIN JUST
W/NW OF VILAS.

WIND CHILL SITN NOT REAL CLEAR CUT. A PERIOD OF GUSTY WINDS
EXPECTED THIS EVENING AS COLD AIR RE-ASSERTS ITSELF ACRS THE AREA.
BUT THEN LATER TNGT WINDS WL DIE OFF TO NEARLY CALM IN C/N-C WI AS
SFC ANTICYCLONE NEARS THE RGN. IN THE END...MAY NOT HAVE A
PROLONGED PERIOD OF WIND CHILLS REACHING ADVISORY CRITERIA. BUT IT
WL BE CLOSE...SO NOT PLANNING ANY CHANGES TO THE HEADLINE AT THIS
POINT.

ACTUAL FCST MIN AIR TEMPS...HOWEVER...SEEMED A LITTLE WARM GIVEN
STRENGTH OF CAA AND CURRENT TEMPS BACK OUT TO THE W. PLUS...SKIES
ARE CLEARING AND SOME AREAS HAVE PROBABLY GOTTEN JUST ENOUGH SNOW
FM THE SHSN THIS AFTN/EVE TO IMPACT TEMPS. EDGED MINS DOWN A
LITTLE FM PREV FCST.

UPDATED PRODUCT SUITE OUT ASAP.

SKOWRONSKI


DISCUSSION ISSUED AT 523 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...FOR 06Z TAF ISSUANCE. SUBSIDENCE HAS RESULTED IN RAPID
CLEARING THIS EVENING. OTHER THAN SOME LINGERING SHSN NEAR THE
UPPER MICHIGAN BORDER AND OVER FAR NRN DOOR COUNTY...VFR
CONDITIONS EXPECTED THROUGH THU.

SKOWRONSKI
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL 6 AM CST THURSDAY FOR WIZ005-010-011-
018-019-030-035-036.

&&

$$








AREA FORECAST DISCUSSION

NWS OMAHA/VALLEY NE

 1128 PM CST FRI JAN 25 2013

.AVIATION...06Z TAFS FOR KOFK...KLNK AND KOMA.

VFR CONDITIONS ARE EXPECTED THROUGH SATURDAY EVENING. HOWEVER
LOWERING CIGS ARE EXPECTED NEAR THE END OF THE TAF PERIOD AND
AFTER AS AN AREA OF RAIN MOVES IN FROM THE SOUTHEAST. SCATTERED TO
BROKEN MID AND HIGH CLOUDS WILL PERSIST BEFORE 06Z SUNDAY WITH
WINDS BECOMING SOUTHERLY 10 TO 20KT. RAIN AND LOWERING CIGS/VSBYS
WILL COMMENCE AFTER 06Z SUNDAY.

DERGAN

&&

.PREV DISCUSSION... /ISSUED 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

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

$$



AREA FORECAST DISCUSSION

NWS NORMAN OK

 1045 PM CST FRI JAN 25 2013

.AVIATION...
NOT MUCH CHANGE FROM PREV SET... EXCEPT TO BE A BIT MORE AGGRESSIVE
WITH STRATUS DEVELOPMENT AND ITS NORTHWARD PUSH DURING THE DAY ON
SATURDAY. STILL APPEARS THAT PRECIP PROBABILITIES REMAIN TO LOW TO
MENTION AT THIS POINT.

30


.PREV DISCUSSION... /ISSUED 959 PM CST FRI JAN 25 2013/

.DISCUSSION...
MAIN UPDATE THIS EVENING IS TO SKY COVER. HRRR AND NAM ARE BOTH
SHOWING A SIGNAL OF THE HIGHER HUMIDITY AT LOW LEVELS /AND
LIKELY THEREFORE STRATUS/ MOVING UP FROM NORTH TEXAS INTO SOUTH
CENTRAL AND CENTRAL OKLAHOMA OVERNIGHT. IT ALSO APPEARS THAT THIS
STRATUS WILL BE PERSISTENT INTO AT LEAST THE MORNING HOURS ON
SATURDAY.. SO HAVE ALSO UPDATED THE SKY GRIDS FOR TOMORROW.
OTHERWISE ONLY MINOR CHANGES WERE NEEDED.

&&

.PREV DISCUSSION... /ISSUED 500 PM CST FRI JAN 25 2013/

AVIATION...
ABUNDANT MID/HIGH CLOUDS WILL CONT TO STREAM ACROSS OKLAHOMA AND
WESTERN NORTH TEXAS OVERNIGHT INTO SATURDAY. LOW LEVEL WINDS WILL
BEGIN TO ADVECT LOW LEVEL MOISTURE BACK NORTHWARD AND COULD SEE
STRATUS DECK APPROACH I-44 CORRIDOR BY SATURDAY AFTN. LIGHT NORTHEAST
WINDS WILL GRADUALLY SHIFT BACK TO THE SOUTH/SOUTHEAST AND WILL
PICK UP IN SPEED... ESPECIALLY LATE IN THE FORECAST OUT WEST.

30

PREV DISCUSSION... /ISSUED 225 PM CST FRI JAN 25 2013/

DISCUSSION...
LOW STRATUS DECK HAS KEPT MUCH OF CENTRAL AND SOUTHERN OKLAHOMA
COOLER THAN EXPECTED TODAY...AS DRIER AIR CONTINUES TO MOVE IN
FROM THE NORTH...HAVE SEEN SLOW EROSION OF STRATUS THIS AFTERNOON.
THIS WILL CONTINUE THROUGH THE EVENING...AND EXPECT CLEARING SKIES
FROM NW TO SE...THOUGH SOME PARTS OF SE OK WILL REMAIN OVERCAST.
AHEAD OF UPPER LEVEL STORM SYSTEM...MID AND UPPER CLOUD COVER WILL
INCREASE THROUGH TONIGHT AND INTO TOMORROW. ABUNDANCE OF CLOUD
COVER WILL KEEP US FROM COOLING OFF TOO MUCH...ESPECIALLY OVER SE
OK...WHERE LOW STRATUS WILL LINGER THROUGH TOMORROW MORNING.

A MODEST UPPER WAVE WILL TRANSLATE ACROSS THE CENTRAL AND
SOUTHERN PLAINS SATURDAY INTO SUNDAY. THIS WILL BRING RAIN CHANCES
BACK TO THE FA...THOUGH THE BEST CHANCES WILL RESIDE ACROSS FAR
NORTH CENTRAL OKLAHOMA AND SRN KANSAS LATE SATURDAY NIGHT. NOT
EXPECTING ANY HEAVY RAINFALL WITH THIS EVENT...AND MOST AREAS THAT
DO GET RAIN WILL SEE FROM ONE TO POSSIBLY TWO TENTHS OF AN INCH OF
TOTAL RAINFALL. PERSISTENT WAA AND INCREASING MOISTURE WILL KEEP
LOWS MUCH ABOVE NORMAL TOMORROW NIGHT AND SUNDAY NIGHT.

AS THE UPPER WAVE EXITS...LEE TROUGH WILL DEVELOP OVER ERN
COLORADO. CONTINUING S/SE FLOW WILL PROMOTE MOISTURE AXIS ACROSS
THE ERN HALF OF OKLAHOMA. THIS AREA WILL LIKELY SEE CLOUDY AND
PERHAPS DRIZZLY CONDITIONS MONDAY INTO TUESDAY. PERSISTENT
SRLY/SWRLY FLOW WILL INDUCE MUCH ABOVE NORMAL HIGHS...WHICH MAY
CLIMB AS HIGH AS 80 DEGREES BY MONDAY.

AS A POTENT UPPER WAVE MOVES OVER THE AREA...WITH STRENGTHENING
SFC CYCLONE OVER THE UPPER MIDWEST...A COLD FRONT WILL BE FORCED
SOUTHWARD ON TUESDAY. AS THIS FRONT COLLIDES WITH THE RELATIVELY
WARM AND MOIST AIRMASS OVER SOUTHEAST OKLAHOMA...EXPECT A GOOD
CHANCE OF THUNDERSTORMS TUESDAY AFTERNOON. BASED ON EXPECTED
MOISTURE AND INSTABILITY...ALONG WITH FAVORABLE WIND
FIELDS...STRONG TO SEVERE STORMS WILL BE POSSIBLE TUESDAY
AFTERNOON...WITH PRIMARILY A HAIL/WIND THREAT. STORMS SHOULD
RAPIDLY MOVE EWD INTO THE MISSISSIPPI VALLEY REGION BY TUESDAY
NIGHT.

FOLLOWING THE COLD FRONT...A PERIOD OF SEASONABLY COOL AND DRY
CONDITIONS IS EXPECTED. LONGER RANGE MODELS HAVE COME INTO BETTER
AGREEMENT TODAY REGARDING POTENTIAL STORM SYSTEM TO MOVE ACROSS
THE SRN PLAINS LATE NEXT WEEK. FOR NOW...THE SYSTEM APPEARS TO
OFFER LITTLE CHANCE OF WINTRY PRECIP...OR ANY PRECIP AT ALL FOR
THAT MATTER...AND WILL KEEP FORECAST DRY FROM WEDNESDAY THROUGH
THE END OF THE PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK  31  54  48  67 /   0   0  40  30
HOBART OK         30  58  46  68 /   0   0  20   0
WICHITA FALLS TX  34  63  51  72 /  10   0  20  10
GAGE OK           29  57  46  72 /   0   0  30   0
PONCA CITY OK     28  58  47  67 /   0  10  60  50
DURANT OK         40  51  49  69 /  10  20  30  20

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&

$$




OTHERWISE...REST OF THE FORECAST DISCUSSION UNCHANGED... MODELS

CONTINUE TO SHOW THE BAROCLINIC ZONE SLOWLY PROGRESSING SE OF THE

 FORECAST AREA TONIGHT..LEAVING THE
REGION IN A COOL MOIST AIR MASS FOR THE WEEKEND. AS THE UPPER LOW
MOVES ACROSS THE AREA SAT AND SUN...THE COLD AIR ALOFT WILL
DESTABILIZE THE AIR MASS TO KEEP A THREAT OF SHOWERS GOING. A COUPLE
OF OTHER FEATURES THOUGH WILL TEND TO ENHANCE POPS AT TIMES...THE
FIRST IS A SHORT WAVE CROSSING 138W THIS AFTERNOON THAT IS EXPECTED
TO PUSH IN LATE TONIGHT AND EARLY SAT. THE SECOND IS A WEAK SYSTEM
DROPPING DOWN FROM THE NNW LATE SUN. WHILE THE GFS AND ECMWF HAVE
CONSISTENTLY HANDLED THIS SYSTEM DIFFERENTLY...THE BOTTOM LINE IS
THAT BOTH SHOW MOIST BUT MODERATE ISENTROPIC LIFT AT 290K...WHICH
SHOULD BE ENOUGH TO JUSTIFY LIKELY POPS BEGINNING LATE SUN. THE
ISENTROPIC LIFT CONTINUES THROUGH SUN NIGHT...AND POSSIBLY INTO MON.
MODELS INDICATE SNOW LEVELS DROPPING DOWN BELOW PASSES...AND
POSSIBLY INTO FOOTHILLS FOR THE WEEKEND. WITH OVERRUNNING SETTING UP
FOR SUN NIGHT AND MON...SNOW LEVELS IN CASCADES LIKELY TO REMAIN ON
THE LOW SIDE.

.LONG TERM...MONDAY NIGHT THROUGH THURSDAY...AN UPPER LEVEL RIDGE
OFF THE WEST COAST REMAINS IN PLACE THROUGH THE END OF THE WEEK. THE
MODELS AGREE ON THE OVERALL PATTERN THOUGH SHOW MINOR DIFFERENCES IN
PLACEMENT OR INTENSITY OF INCOMING FRONTS. BASICALLY...SHOWERS TAPER
OFF TUESDAY IN THE WAKE OF AN EAST-MOVING FRONT. THE GFS HOLDS
SHOWERS OVER THE CWA ON WED IN THE WAKE OF THE FRONT...WHILE THE
ECMWF AND GEM ARE MUCH LIGHTER WITH QPF. THE NEXT SIGNIFICANT SYSTEM
WOULD BE SOMETIME THURSDAY...AND AGAIN THE GFS IS MUCH MORE BULLISH
WITH PRECIPITATION AS THE SYSTEM DROPS OVER THE RIDGETHURSDAY.
WILL STAY WITH CURRENT POPS EXCEPT TO TAPER SOUTHERNMOST AREAS TO
LOW CHANCE OR SLIGHT CHANCE. WEDNESDAY HAS A GOOD CHANCE FOR BEING
THE DRIEST DAY IF THE ECMWF IS RIGHT BUT WILL WAIT UNTIL MODELS
SETTLE SOMEWHAT. ANOTHER BRIEF DRY PERIOD LOOKS POSSIBLE FRIDAY INTO
THE WEEKEND AS MODELS AGREE ON PUSHING THE UPPER RIDGE INLAND AS
PATTERN BECOMES PROGRESSIVE. KWELSON
&&

.AVIATION...THE NEXT SYSTEM WILL BRING RAIN TO THE COAST AROUND
08Z TONIGHT AND INLAND 10Z-13Z. A FEW AREAS OF LIFR FOG WILL
CONTINUE ACROSS THE CENTRAL AND SOUTH WILLAMETTE VALLEY THROUGH
08Z-10Z...OTHERWISE EXPECT PRIMARILY MVFR AND IFR STRATUS ACROSS
MOST AREAS. A MIX OF VFR AND MVFR CONDITIONS EXPECTED IN SHOWERS
ON SATURDAY.

KPDX AND APPROACHES...LITTLE IN THE WAY OF MIXING EXPECTED THROUGH
TONIGHT SO CURRENT IFR CONDITIONS WILL LIKELY CONTINUE TONIGHT.
EXPECT A MIX OF VFR AND MVFR CONDITIONS IN SHOWERS ON SATURDAY.

&&

.MARINE...A FRONT WILL INCREASE SOUTHERLY WINDS TO NEAR 20 KT
LATE TONIGHT INTO EARLY SAT THEN EASE. A WEAKER FRONT ARRIVES SUN
MORNING...THEN HIGH PRES MOVE CLOSER TO THE PACNW MON THROUGH MID
WEEK FOR NWLY WINDS. LONG PERIOD SWELL AT OR ABOVE 10 FEET WILL
CONTINUE THROUGH SAT NIGHT.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 AM PST SUNDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR
     OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH BAR UNTIL 10 PM PST SATURDAY FOR
     COLUMBIA RIVER BAR.

&&

$$

MORE WEATHER INFORMATION ONLINE AT...HTTP://WEATHER.GOV/PORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.






AREA FORECAST DISCUSSION

NWS HOUSTON/GALVESTON TX

 1123 PM CST FRI JAN 25 2013

.UPDATE...
06Z TAF DISCUSSION IN AVIATION SECTION.

&&

.AVIATION...
SFC ANALYSIS AT 05Z HAS WEAK FRONTAL BOUNDARY FROM JUST SOUTH OF
KCLL TO NEAR KOCH. DO NOT SEE BOUNDARY WORKING ANY FARTHER SOUTH
TONIGHT. MAIN CONCERN TONIGHT WILL BE LOW CIGS AND PATCHY FOG THAT
MAY LIMIT VSBY TO MVFR LEVELS. STARTING TO SEE SOME HIGH LEVEL
CLOUDS THICKEN OVER SE TX PER IR/LOW CLOUD SATELLITE IMAGERY. HIGH
CLOUDS SHOULD LIMIT THE DEVELOPMENT OF FOG AND THERE IS ALSO A
MVFR STRATUS DECK TO CONTEND WITH OVER MUCH OF THE HOUSTON AREA.
DECIDED TO MAINLY GO MVFR FOR VSBY FOR TAF SITES AND TEMPO
POSSIBILITY OF IFR CIGS. OTHERWISE THINK CIGS WILL REMAIN AROUND
MVFR LEVELS FOR MUCH OF THE NIGHT. WILL NEED TO MONITOR KGLS FOR
SEA FOG BUT THERE HAS BEEN NO DEVELOPMENT AS OF YET. WINDS DO
CONTINUE TO TURN TO THE SE ALONG THE COAST TONIGHT BUT THINK BEST
CHANCE FOR SEA FOG WILL BE TOMORROW EVENING AS WINDS BECOME MORE
SE/ESE WITH TIME. THINK MVFR CIGS SHOULD LIFT DURING THE LATE
MORNING WITH SE WINDS INCREASING THROUGH THE AFTERNOON. THINK
TOMORROW NIGHT WILL HAVE ANOTHER ROUND OF MVFR CIGS.

39

&&

.PREV DISCUSSION... /ISSUED 950 PM CST FRI JAN 25 2013/

DISCUSSION...
AT 9 PM...THE WEAK COLD FRONT HAD MOVED THROUGH BRENHAM AND WAS
APPROACHING COLLEGE STATION...MADISONVILLE...AND CROCKETT. THE
LATEST HIGH RES AND RAP MODELS ALL INDICATE THAT THE FRONT WILL
SINK SOUTHWARD A BIT OVERNIGHT TONIGHT BEFORE MOVING BACK
NORTHWARD ON SATURDAY. A BIT OF A LOW-LEVEL JET HAS FORMED THIS
EVENING AS SHOWN ON THE KHGX AND THOU VAD WIND PROFILES JUST ABOVE
1000 FEET. SOME SLIGHTLY DRIER AIR WAS LOCATED OVER GALVESTON BAY
AND THE IMMEDIATE COASTAL AREAS EAST OF FREEPORT. THE MODELS
ACTUALLY CONTINUE THIS TREND THROUGH THE NIGHT. IN ADDITION TO
THE POSSIBLE LOW CLOUDS...HIGHER LEVEL CLOUDS WILL MOVE OVERHEAD
FOR AT LEAST THE NEXT FEW HOURS. BECAUSE OF THESE LIMITING
FACTORS...FELT THAT THE FOG THREAT IS NOW LOWER THAN EARLIER
ANTICIPATED. HOWEVER...THERE ARE A FEW CAVEATS. IF THE FRONT SAGS
A BIT FURTHER TO THE SOUTH IT WILL HELP POOL THE LOW-LEVEL
MOISTURE A BIT HIGHER. THIS MAY THEN HELP BACK THE WINDS A BIT TO
BE MORE FROM THE EAST-SOUTHEAST. IF THESE EVENTS OCCUR...THE
CHANCES FOR SEA FOG FORMATION WILL INCREASE.

HOWEVER...FOR NOW UPDATED THE WEATHER TO TAKE OUT THE DENSE FOG
AND TO GO WITH JUST PATCHY FOG. ALSO UPDATED THE CLOUD COVER...
DEWPOINTS...AND HUMIDITY.

40

PREV DISCUSSION... /ISSUED 557 PM CST FRI JAN 25 2013/

DISCUSSION...
00Z TAF DISCUSSION IN AVIATION SECTION.

AVIATION...
AS HAS BEEN THE CASE FOR THE BETTER HALF OF A WEEK...FOG WILL BE
THE MAIN AVIATION CONCERN FOR THE TAFS. PREVIOUS TAF PACKAGE MAY
HAVE BEEN TOO PESSIMISTIC SO THERE WILL BE SOME FURTHER
MODIFICATIONS GOING TOWARDS 06Z TAF CYCLE. FOR NOW WILL KEEP SOME
MENTION OF LIFR/IFR CIGS BUT LOOKING AT WIND FIELDS FROM THE S/SW
AND TD NOT AS HIGH AS FORECASTED...HAVE SOME DOUBTS TO HOW MUCH
FOG WILL DEVELOP. THINK LOW VSBY FOG WILL BE CONFINED TO COAST BUT
HOW MUCH FARTHER IT DEVELOPS IS THE MAIN QUESTION. WILL KEEP LIFR
MENTIONED FOR KHOU BUT ONLY MENTION IFR CIG AT KIAH. SEEMS MODEL
TRENDS MAY BE POINTING TO NOT BEING AS PESSIMISTIC WITH FOG AND
NOT TURNING WINDS TO THE SE AS MUCH AS PREVIOUSLY PROGGED. WILL
MONITOR 00Z GUIDANCE AND LIKELY MAKE FURTHER MODIFICATIONS TO TAFS
BASED OFF 00Z GUIDANCE AND ONGOING TRENDS.

39

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      58  75  59  74  63 /  10  10  10  10  20
HOUSTON (IAH)              61  77  60  75  63 /  10  10  10  10  20
GALVESTON (GLS)            59  72  61  71  62 /  10  10  10  10  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

DISCUSSION...40
AVIATION/MARINE...39



AREA FORECAST DISCUSSION

NWS CHEYENNE WY

 1025 PM MST FRI JAN 25 2013

.AVIATION...06Z TAF ISSUANCE...

HAVE SOME LOWER CLOUDS BEING OBSERVED OUT BY RAWLINS LATE THIS
EVENING. LATEST MODEL SOUNDINGS SHOWING RAWLINS DROPPING TO MVFR
AS EARLY AS 10Z...WHILE HRRR FORECAST SHOWING SOME IFR CONDITIONS
AROUND RAWLINS IN CARBON COUNTY. CONFIDENCE NOT HIGH ON IFR
HAPPENING OUT THAT WAY AS HRRR HAS A HARD TIME WITH RAWLINS. AS A
COMPROMISE...WENT WITH LOW MVFR CEILINGS OUT THAT WAY TOWARDS
11Z...PERSISTING THROUGH MOST OF THE MORNING. ELSEWHERE...VFR
CONDITIONS EXPECTED FOR AIRPORTS EAST OF THE LARAMIE RANGE.

CLAYCOMB

&&

PREV DISCUSSION... /ISSUED 318 PM MST FRI JAN 25 2013/

SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...

GENERALLY QUIET WEATHER CONDITIONS ACROSS THE CWA THIS AFTERNOON.
WITH A LEE TROUGH ALONG THE WY-NE BORDER AND THE SFC HIGH OVER
NORTHERN UTAH...THERE IS ENOUGH OF A LLVL PRESSURE GRADIENT TO GET
A FEW WIND GUSTS TO 40-45 MPH IN THE GAP AREAS OF ARLINGTON AND
BORDEAUX THROUGH THE EVENING. WATER VAPOR IMAGERY SHOWS A CUTOFF
LOW OFF THE SOUTHERN CALIFORNIA COAST WITH ABUNDANT SUBTROPICAL
MOISTURE STREAMING NORTHWARD AHEAD OF IT. THE MODELS ARE IN
AGREEMENT IN SHOWING THIS SYSTEM WEAKENING CONSIDERABLY AS IT
MOVES NORTHEASTWARD INTO COLORADO BY TOMORROW AFTN. EVEN WITH THE
MAIN MOISTURE PLUME AND DYNAMICS REMAINING LARGELY OVER
COLORADO...THE GFS AND ECMWF BOTH SHOW VERY GOOD 700-500MB
MOISTURE IN THE SOUTHERN ZONES BETWEEN 00Z AND 12Z SUNDAY.
THUS...INTRODUCED SLIGHT CHANCE POPS OVER THE PLAINS MAINLY ALONG
THE COLORADO BORDER ON SATURDAY NIGHT. LOOKING FOR LIKELY POPS
OVER THE SIERRA MADRE AND SNOWY RANGES WITH THE ADDITION OF
OROGRAPHICS IN THE MTNS. DUE TO THE WARM SUBTROPICAL NATURE OF
THE SYSTEM...WET BULB ZERO PRESSURES ARE AROUND 775MB...SO COULD BE
A MIX OF LIGHT RAIN AND SNOW ON THE PLAINS IN WHATEVER PRECIP
AREAS THAT DEVELOP. THE SYSTEM QUICKLY BECOMES ABSORBED IN THE
SOUTHWESTERLY FLOW ALOFT BY SUNDAY MORNING AND MOVES OFF INTO THE
CENTRAL PLAINS...ENDING THE PRECIP THREAT TO THE EAST OF THE
LARAMIE RANGE.

THE MEDIUM RANGE MODELS CONTINUE TO SHOW A LARGE SCALE TROUGH
DIGGING INTO THE GREAT BASIN ON SUNDAY WITH STRENGTHENING
SOUTHWESTERLY MIDLEVEL FLOW OVER THE CWA. WITH 700MB TEMPS AROUND
-2C...THE AREA WILL SEE ANOTHER DAY OF ABOVE NORMAL TEMPS. LARGE
SCALE ASCENT AND INCREASING MOISTURE WILL OVERSPREAD AREAS TO THE
WEST OF THE LARAMIE RANGE BY SUNDAY NIGHT...SO HAVE HIGH END
CHANCE POPS IN THE MTNS AND SLIGHT CHANCE POPS ACROSS THE LOWER
ELEVATIONS AT THAT TIME. ONE MORE MILD NIGHT FOR SUNDAY BEFORE A
COLD FRONT PASSES ACROSS THE REGION ON MONDAY.

LONG TERM...MONDAY THROUGH THURSDAY NIGHT...

OVERALL CONFIDENCE IN THE EXTENDED IS LOW GIVEN A LACK OF CONSISTENCY
BETWEEN MODEL RUNS AND...DIFFERENCES BETWEEN COMPETING EXTENDED
MODELS. STARTING OFF MONDAY...UPPER LEVEL TROUGH FORECAST TO MOVE
INTO THE ROCKIES. THE MAIN QUESTION IS THE TRACK OF THE MAIN UPPER
LEVEL CIRCULATION AND HOW FAST A COLD FRONT MOVE ACROSS THE AREA.
GFS SHOOTS UPPER LEVEL ENERGY NORTHWARD INTO COLORADO MONDAY NIGHT
INTO TUESDAY...WHICH WOULD MEAN A DECENT SHOT OF SNOW ACROSS THE
FORECAST AREA DURING THAT TIME. EC ON THE OTHER HAND HAS BEEN
HINTING AT A CLOSING AN UPPER LEVEL CIRCULATION OVER THE NORTHERN
CALIFORNIA BAJA MONDAY WHICH WOULD KEEP THE MAIN POTENTIAL FOR
SNOW SOUTH OF THE FORECAST AREA. AT THIS TIME KEPT LOW POPS GOING
ACROSS THE PLAINS MONDAY NIGHT AND TUESDAY. SHOULD THE GFS VERIFY
MAINLY LOOKING AT 1 TO 4 INCH ACCUMULATIONS WHILE THE EC SUGGEST A
DUSTING AT BEST.

SLIGHTLY MORE CONFIDENT LOWERING FORECAST HIGHS IN THE
EXTENDED...ESPECIALLY TUESDAY AND WEDNESDAY. EXTENDED MODELS IN
BETTER AGREEMENT WITH A SHOT OF COLD AIR EARLY NEXT WEEK. OF COURSE
TEMPERATURES WOULD BE EVEN COLDER SHOULD SEVERAL INCHES OF SNOW FALL
IN THE PLAINS. MAIN SHOT OF COLD AIR SHOULD COME DOWN MONDAY WITH
COLD AIR IN PLACE TUESDAY. SHOULD SEE WARMING AT THE HIGHER
ELEVATIONS WEDNESDAY AND THURSDAY...BUT THE PLAINS MAY STRUGGLE TO
WARM AS QUICKLY. MAY BE VERY SIMILAR TO EARLIER THIS WEEK WHEN A
SHALLOW COLD AIR MASS HELD IN PLACE OVER THE NEBRASKA PANHANDLE.
COULD EASILY SEE A 20 DEGREE HIGH TEMPERATURES DIFFERENCE BETWEEN
CHEYENNE AND CHADRON COME THURSDAY.

AVIATION...18Z TAF ISSUANCE...

VFR AT ALL TAF SITES WITH THE EXCEPTION OF RAWLINS WHERE LOW
CLOUDS WILL PERSIST TODAY AND TONIGHT. BREEZY CONDITIONS MAINLY
WEST OF THE LARAMIE RANGE WITH LIGHT WINDS EAST INTO THE PLAINS.

FIRE WEATHER...

FIRE WEATHER CONCERNS WILL BE MINIMAL THROUGH EARLY NEXT WEEK.
TEMPERATURES WILL CONTINUE TO BE ABOVE NORMAL AREAWIDE THROUGH
MONDAY WITH BREEZY WESTERLY WINDS ACROSS SOUTHEAST WYOMING.
AFTERNOON HUMIDITIES WILL GENERALLY BE ABOVE 35 PERCENT. A STORM
SYSTEM WITH MOVE ACROSS THE REGION ON MONDAY AFTERNOON THROUGH
TUESDAY BRINGING A CHANCE OF LIGHT SNOW ALONG WITH COLDER
TEMPERATURES.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.

&&

$$

SHORT TERM/FIRE WEATHER...FINCH
LONG TERM/AVIATION...LIEBL







AREA FORECAST DISCUSSION

NWS SACRAMENTO CA

 330 AM PST SAT JAN 26 2013

.SHORT TERM DISCUSSION...
WEAK FRONTAL BAND MOVING THROUGH NORCAL AT THIS TIME HAVING MINIMAL
IMPACT ON THE FORECAST AREA. GENERALLY ONLY THE NORTHERN PORTIONS OF
THE CWA ARE SEEING CLOUDINESS FROM THIS SYSTEM WITH ONLY VERY LIGHT
ECHOS INDICATED ON RADAR. FARTHER SOUTH...SKIES ARE CLEAR ENOUGH TO
ALLOW WIDESPREAD FOG FORMATION THROUGHOUT THE CENTRAL VALLEY AND
DELTA. SATELLITE FOG PRODUCT SHOWING MOST OF THE CENTRAL VALLEY
FILLING IN WITH THIS FOG AND LOW STRATUS ALTHOUGH SO FAR VISIBILITY
HAS KEPT FROM GOING DENSE. WILL NEED TO KEEP AN EYE OUT FOR NEED OF
A DENSE FOG ADVISORY LATER THIS MORNING. UPPER EASTERN PACIFIC
TROUGH FORECAST TO BEGIN PUSHING INTO NORTHWEST CORNER OF THE STATE
BY THIS AFTERNOON. COMBINATION OF LOW LEVEL MOISTURE AND OROGRAPHICS
WILL MAKE FOR A THREAT OF PRECIPITATION OVER THE MOUNTAINS BUT WITH
WEAK DYNAMICS GENERATED BY THE TROUGH...CAN NOT RULE OUT A SLIGHT
THREAT OF PRECIP ELSEWHERE. COLDER AIR WITHIN THE TROUGH WILL BEGIN
FILTERING INTO THE REGION THIS AFTERNOON BRINGING LOWER SNOW LEVELS
AND A COOLING TREND BUT MILD AIRMASS CURRENTLY IN PLACE WILL STILL
KEEP DAYTIME HIGHS TODAY A LITTLE ABOVE NORMAL. UPPER TROUGH AXIS
WILL PUSH INTO NORCAL TONIGHT BRINGING AN BETTER THREAT OF PRECIP TO
THE ENTIRE CWA. SNOW LEVELS WILL CONTINUE TO FALL DROPPING TO BELOW
2000 FEET BY SUNDAY MORNING. FORECAST MODELS STILL INDICATING THIS
TROUGH CONTAINS FAIRLY DRY AIR SO PRECIP AMOUNTS STILL FORECAST TO
BE ON THE MINIMAL SIDE. BY SUNDAY AFTERNOON...THE MAIN TROUGH AXIS
SHOULD BE EAST OF THE STATE PUTTING MOST OF NORCAL UNDER UPPER LEVEL
NORTHERLY FLOW. WEAK DISTURBANCES DROPPING SOUTHWARD IN THIS FLOW
COULD CONTINUE TO BRING A THREAT OF PRECIP ESPECIALLY OVER THE
EASTERN SIDE OF THE FORECAST AREA OVER THE SIERRA CASCADES. THE
NORTHERLY FLOW AND COOLER AIRMASS SHOULD PUSH DAYTIME HIGHS SUNDAY
DOWN TO BELOW NORMAL FOR THIS TIME OF YEAR. BY MONDAY...MID RANGE
MODELS ARE IN GOOD AGREEMENT IN SLIDING UPPER RIDGE EASTWARD OVER
THE WEST COAST. THIS SHOULD BRING A DRYING AND CLEARING TREND FROM
THE WEST ALTHOUGH SOME RAP AROUND MOISTURE AND CLOUDINESS WILL
LIKELY REMAIN OVER THE SIERRA. UPPER RIDGING AND CLEARING SKIES WILL
BRING A LIKELY RETURN OF VALLEY FOG BY TUESDAY MORNING. ONCE THIS
FOG CLEARS OUT...TUESDAY SHOULD SHAPE UP TO BE A FAIRLY CLEAR DAY
UNDER A BUILDING UPPER RIDGE WHICH IS FORECAST TO HOLD THROUGH MUCH
OF THE COMING WEEK.

.EXTENDED DISCUSSION (WEDNESDAY THROUGH SATURDAY)
MEDIUM RANGE MODELS SHOWING UPPER LEVEL RIDGING TO BE THE MAIN
SYNOPTIC FEATURE THROUGH THE EXTENDED PERIOD. RESULT WILL BE DRY
WEATHER TUESDAY THROUGH SATURDAY WITH SOME NIGHT AND MORNING VALLEY
FOG. HIGH TEMPERATURES EXPECTED 5 TO 10 DEGREES ABOVE NORMAL.
LOCALLY BREEZY NORTH TO EAST WIND POSSIBLE...MAINLY OVER THE
NORTHERN AND EASTERN MOUNTAINS/FOOTHILLS...THROUGH EARLY FRIDAY.
SLIGHT COOLING SATURDAY AS UPPER RIDGING WEAKENS.

&&

.AVIATION...
WK PAC FNT AND ASSOCD UPR TROF MOV THRU OVR THE WKND. OVR NRN/CSTL
MTNS...LCL MVFR/IFR CONDS POSS IN -SHRA WITH SN LVLS AOA 065 AMSL.
FOR CNTRL VLY...WDSPRD IFR/LIFR IN FG/ST THRU ABT 19Z AND AGN TNGT
INTO SUN MRNG. OVR SIERNEV FTHLS/W SLPS...WDSPRD MVFR CIGS WITH
AREAS IFR AND LCL LIFR IN -SHRA AND VLY FOG/ST WITH SN LVLS AOA 065
AMSL.

&&

.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&

$$











AREA FORECAST DISCUSSION

NWS LA CROSSE WI

 530 AM CST SAT JAN 26 2013

.SHORT TERM...TODAY THROUGH MONDAY NIGHT
413 AM CST SAT JAN 26 2013

MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES...TYPES AND
AMOUNTS FOR SUNDAY AND SUNDAY NIGHT.

CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED TROUGHING OFF THE PACIFIC NORTHWEST COAST...AN UPPER LOW NEAR
SAN DIEGO CA...RIDGING PROGRESSING INTO THE NORTHERN PLAINS...AND
TROUGHING FROM SOUTHEAST CANADA INTO NEW ENGLAND. THE FORECAST AREA
LIES IN THE SUBSIDENT PORTION AHEAD OF THE UPPER RIDGING...RESULTING
IN DRYING AND HIGH PRESSURE AT THE SURFACE. 00Z MPX SOUNDING SHOWED
A LOT OF DRY AIR ABOVE 800MB...WITH A PRECIPITABLE WATER OF 0.17
INCHES OVERALL. SATELLITE IMAGERY DEPICTS MAINLY CLEAR SKIES OVER
THE FORECAST AREA. AIRMASS ASSOCIATED WITH THE HIGH PRESSURE AREA
WAS ALSO RELATIVELY CHILLY WITH A 925MB TEMP OF -17C AT MPX.
COMBINATION OF THE CLEAR SKIES...DIMINISHING WINDS AND THE CHILLY
AIR HAS ALLOWED TEMPERATURES TO DROP INTO THE SINGLE DIGITS ABOVE
ZERO. TO THE NORTHWEST...MID AND HIGH CLOUDS WERE STREAMING ACROSS
NORTH DAKOTA AND NORTHWEST MN...ASSOCIATED WITH PACIFIC MOISTURE ON
WATER VAPOR BECOMING ENHANCED BY UPPER JET FORCING...AS WELL AS WARM
ADVECTION. WELL TO THE SOUTH...AN AREA OF PRECIPITABLE WATER VALUES
OF 0.8 INCHES AND HIGHER WAS PRESENT ACROSS MUCH OF TEXAS AND
LOUIS ANA...WELL DOWNSTREAM OF THE SAN DIEGO UPPER LOW.

TODAY AND TONIGHT...MODELS SHOW THE TROUGHING JUST OFF THE PACIFIC
NORTHWEST DIGGING INTO NORTHERN CALIFORNIA. ALTHOUGH THIS IS QUITE
FAR AWAY FROM HERE...THERE ARE NUMEROUS IMPACTS FROM IT. THE FIRST
IS TO KEEP PUSHING THE RIDGING COMING INTO THE NORTHERN PLAINS
EASTWARD...WITH ITS RIDGE AXIS PROGGED TO BE CENTERED OVER THE
FORECAST AREA AT 12Z SUNDAY. WARMER AIR WILL ACCOMPANY THE RIDGE...
WITH 925MB TEMPS CLIMBING TO -6 TO -10C BY 00Z AND -2 TO -5C BY 12Z
SUNDAY. THE SECOND IMPACT IS TO EJECT AND POSSIBLY SHEAR OUT THE SAN
DIEGO CA UPPER LOW...LIFTING IT UP TO AROUND GOODLAND KS BY 12Z
SUNDAY. AS THIS UPPER LOW APPROACHES THE CENTRAL PLAINS TONIGHT...A
LOW LEVEL JET DEVELOPS...PULLING THE MOISTURE SEEN ACROSS TEXAS
NORTHWARD. AT 12Z SUNDAY...PRECIPITABLE WATER VALUES BETWEEN 0.8-1
INCHES ARE POSSIBLE AS FAR NORTH AS DES MOINES IA AND OMAHA
NE...WHICH ARE ALMOST 300 PERCENT ABOVE NORMAL. WITH SO MUCH
MOISTURE RUNNING INTO A DRY AND COLDER AIRMASS PRESENT HERE ACROSS
THE UPPER MIDWEST...LOW CLOUDS AND PRECIPITATION SHOULD EASILY
DEVELOP. 26.00Z NAM/GFS/ECMWF/CANADIAN/UKMET ARE ALL IN GOOD
AGREEMENT KEEPING ANY PRECIPITATION SOUTH OF THE AREA PRIOR TO 12Z.
NOTE...THOUGH...THAT BY 12Z...PRECIPITATION SHOULD BE PRESENT FROM
KANSAS CITY TO OMAHA AND DES MOINES. FULL SUN THIS MORNING FOLLOWED
BY FILTERED SUN THROUGH MID/HIGH CLOUDS IN THE AFTERNOON...COMBINED
WITH THE WARMER AIR MOVING IN AND LIMITED SNOW ON THE GROUND...
SHOULD ALLOW TEMPERATURES TO CLIMB INTO THE LOW TO MID 20S. CLOUDS
FURTHER INCREASE TONIGHT...AND WITH WINDS PICKING UP ADVECTING
WARMER/MOIST AIR IN...THINK TEMPERATURES WILL FALL JUST A LITTLE IN
THE EVENING THEN MOSTLY HOLD STEADY OR RISE. FINAL NOTE ABOUT THE
CLOUD INCREASE TONIGHT...BOTH THE GFS AND REGIONAL CANADIAN PRODUCE
A LITTLE LIGHT SNOW ACROSS TAYLOR/CLARK COUNTIES FROM THE MID CLOUDS
THIS EVENING. ADDED SOME FLURRIES FOR NOW...GIVEN DRY WEATHER
SIGNALED BY OTHER MODELS.

SUNDAY AND SUNDAY NIGHT...THE TROUGHING DIGGING INTO NORTHERN
CALIFORNIA IS FORECAST TO DIG EVEN MORE DURING THIS PERIOD...AIDED
TOO BY A POTENT SHORTWAVE DROPPING THROUGH THE PACIFIC NORTHWEST.
THE RESULT BY 12Z MONDAY IS A FULL-FLEDGED TROUGH OVER THE WESTERN
1/3 OF THE U.S. IN RESPONSE...500MB HEIGHTS RISE DOWNSTREAM ACROSS
THE REST OF THE U.S.. THIS WILL CAUSE THE SHEARING OUT UPPER LOW
NEAR GOODLAND KS AT 12Z TO LIFT UP INTO THE FORECAST AREA BY 00Z
MONDAY. MODELS STILL DIFFER A BIT ON STRENGTH...BUT THE GENERAL
CONSENSUS IS THAT THE PRECIPITATION THAT DEVELOPS TONIGHT AROUND THE
KC...OMAHA AND DES MOINES AREAS WILL END UP TRANSLATING NORTHEAST
WITH THE SHEARING OUT UPPER LOW...IMPACTING THE FORECAST AREA. GOOD
SETUP FOR PRECIPITATION AS THE SURGE OF HIGH PRECIPITABLE WATER (FOR
THIS TIME OF YEAR) COMBINES WITH ISENTROPIC LIFT AND DPVA FROM THE
SHORTWAVE. REALLY GOOD AGREEMENT EXISTS NOW THAT MUCH OF THE AREA
BETWEEN 18Z SUNDAY AND 06Z MONDAY WILL SEE PRECIPITATION. IN
FACT...EVEN THE EXPECTED AMOUNTS BETWEEN THE 26.00Z
GFS/UKMET/ECMWF/CANADIAN...26.06Z NAM AND 26.03Z SREF ARE ALL REALLY
CLOSE...IN THE 0.25-0.6 RANGE...AND AGAIN MUCH OF THIS FALLING
DURING THAT 18Z SUN - 06Z MON. THE HIGHEST MAXIMUM HAS SHIFTED
NORTH...AFFECTING THE SOUTHEAST HALF OF THE FORECAST AREA INTO
NORTHERN ILLINOIS. GIVEN THE GREAT MODEL AGREEMENT...HAVE RAISED
PRECIPITATION CHANCES EVEN MORE. IT IS INTERESTING SCENARIO WITH
REGARDS TO PRECIPITATION TYPE. INITIALLY THERE IS SOME DRY AIR TO
OVERCOME WHILE WARM ADVECTION IS TAKING PLACE. THIS FAVORS MORE OF
FREEZING RAIN/SLEET AT THE ONSET...TRANSITIONING TO SLEET/SNOW
QUICKLY AS DYNAMIC COOLING TAKES OVER. YOU CAN SEE THIS NICELY IN
850MB TEMPS FROM THE MODELS. AS TIME PROGRESSES THROUGH THE
AFTERNOON AND EVENING...EVENTUALLY THE WARM AIR STARTS SPREADING
NORTH THROUGH THE AREA...CAUSING THE SNOW OR SLEET TO TRANSITION TO
FREEZING RAIN...ESPECIALLY SOUTH OF I-90. THEN...TO MAKE MATTERS
WORSE...THE ICE BEGINS TO LEAVE THE CLOUDS...LEAVING WHAT WILL
PROBABLY BE A FREEZING DRIZZLE AFTER MIDNIGHT. IN SUMMARY...A MESS.
COULD REALLY SEE A DECENT AMOUNT OF SLEET IN THIS EVENT...ESPECIALLY
ALONG/SOUTH OF I-90...SINCE THE BALANCE OF COOLING FROM
PRECIPITATION AND THE WARM ADVECTION KEEPS THE MAX TEMPERATURE ALOFT
IN THE 1-3C RANGE. GIVEN THAT WE COULD HAVE VARIOUS PRECIPITATION
TYPES EXCEEDING WARNING CRITERIA...AS WELL AS THE MODEL TRENDS NORTH
WITH THE MAX QPF...HAVE ISSUED A WINTER STORM WATCH EVERYWHERE
EXCEPT FOR TAYLOR WHICH LOOKS TOO FAR NORTH TO WARRANT A WATCH AT
THIS TIME. ON A SIDE NOTE...AFTER THE PRECIPITATION DIMINISHES TO
DRIZZLE...SETUP LOOKS FAVORABLE FOR FOG FORMATION. RECENT
PRECIPITATION PLUS DRYING ALOFT...LIGHT WINDS AND COLD GROUND ALL
SPELL FOG. ADDED AREAS OF FOG TO THE FORECAST AFTER MIDNIGHT SUNDAY
NIGHT.

MONDAY AND MONDAY NIGHT...MODELS SHOW THAT THE WESTERN TROUGH SLIDES
SLOWLY EASTWARD DURING THIS PERIOD...WITH A NEW LOW PRESSURE AREA
DEVELOPING OVER THE CENTRAL PLAINS. SUBSIDENCE IN THE WAKE OF THE
SUNDAY/SUNDAY NIGHT SYSTEM WILL LEAVE THE AREA DRY FOR MONDAY. NOTE
THAT THERE IS TRAPPED MOISTURE BELOW THE SUBSIDENCE INVERSION...BUT
26.00Z GFS/NAM SOUNDINGS DO NOT DEPICT ANY LIFT WITHIN THIS CLOUD
LAYER. THUS...THE SMALL PRECIPITATION CHANCES WERE REMOVED.
HOWEVER...FOG STILL LOOKS LIKE A GOOD BET FOR THE MORNING. SREF
VISIBILITY PROGS FOR LESS THAN 1 MILE ARE QUITE IMPRESSIVE AT 12Z
MONDAY WHEN LOOKING AT A REGIONAL PERSPECTIVE. WITH THE
PRECIPITATION SHUT OFF ON MONDAY...925MB TEMPS ARE REALLY ALLOWED TO
WARM...CLIMBING TO 0-4C BY 00Z TUESDAY. THUS...MOST LOCATIONS SHOULD
SEE HIGHS POP ABOVE FREEZING EVEN DESPITE THE CLOUDS. IN FACT...FAR
SOUTHERN AREAS COULD GET CLOSE TO 40. A NEW ROUND OF ISENTROPIC LIFT
STARTS UP MONDAY NIGHT AS THE LOW PRESSURE SYSTEM FORMS OVER THE
CENTRAL PLAINS. THERE ARE DIFFERENCES IN THE AMOUNT OF LIFT...BUT
THERE SHOULD BE ENOUGH TO SPREAD AT LEAST SOME LIGHT QPF ACROSS THE
AREA. GIVEN THAT MODEL FORECASTS HAVE THE NEAR SURFACE AIR COLD
ADVECTING WHILE THE AIR ALOFT SAY AT 850MB STAYS WARM (TEMPS ABOVE
2C)...CONCERNED THAT WE COULD END UP WITH FREEZING RAIN AND THUS
ADDED IT TO THE FORECAST.

.LONG TERM...TUESDAY THROUGH FRIDAY NIGHT
413 AM CST SAT JAN 26 2013

THE TWO BIG HIGHLIGHTS HERE ARE THE CENTRAL PLAINS SYSTEM FROM
MONDAY NIGHT AND THE CONSISTENT SURGE OF ARCTIC AIR PROGGED TOWARDS
THE MIDDLE OF THE WEEK. MODELS HAVE REALLY CHANGED THEIR TUNE FROM
YESTERDAY...NO LONGER CUTTING OFF THE SOUTHERN PORTION OF THE
WESTERN TROUGH. NOW THE WESTERN TROUGH IS SUGGESTED BY PRETTY MUCH
EVERY MODEL TO PROGRESS EASTWARD. AS IT DOES...THE CENTRAL PLAINS
LOW WILL LIFT NORTHEAST. THE BIG QUESTION MARK IS GOING TO BE
WATCHING HOW STRONG THIS LOW IS...WHICH DEPENDS ON HOW QUICK ARCTIC
AIR CAN COME DOWN INTO THE NORTHERN PLAINS. THE NEW 26.06Z GFS AND
TO SOME DEGREE THE 26.00Z CANADIAN PHASE THE TWO TOGETHER...
RESULTING IN A DEEP LOW. HOWEVER...THE ECMWF MAINTAINS A MORE
POSITIVELY TILTED LOOK...THUS A WEAKER LOW AND MUCH LESS QPF AND
WIND. NONETHELESS...CHANCES OF PRECIPITATION ARE REQUIRED FOR
TUESDAY THROUGH WEDNESDAY FOR THE BACK SIDE OF THE SYSTEM. IT IS
POSSIBLE TUESDAY WE COULD STILL BE DEALING WITH SNOW...RAIN...SLEET
AND FREEZING RAIN...BUT FOR NOW HAVE KEPT IT TO RAIN/SNOW. ARCTIC
AIR THEN RUSHES IN FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. 850MB
TEMPS PLUMMET TO -20 TO -24C. HIGH PRESSURE BUILDS IN FOR FRIDAY
WITH PERHAPS A NORTHWEST FLOW SYSTEM APPROACHING THE AREA FRIDAY
NIGHT.

&&

.AVIATION...TODAY AND TONIGHT
530 AM CST SAT JAN 26 2013

DRY AND COOL CANADIAN HIGH PRESSURE OVER THE REGION EARLY THIS
MORNING WILL MOVE QUICKLY EAST OF THE AREA TODAY...BUT ITS INFLUENCE
WILL PERSIST ACROSS THE AREA THRU TONIGHT. GOOD VFR CONDITIONS
EXPECTED THRU TONIGHT AS THE DRIER LOW LEVEL AIRMASS FROM THE HIGH
REMAINS OVER THE AREA. GRADIENT WILL TIGHTEN FOR THIS AFTERNOON/
TONIGHT AS THE CENTER OF THE HIGH MOVES AWAY...BUT THE INCREASE OF
SOUTHEAST WINDS WILL KEEP THE FLOW OF DRIER LOW LEVEL AIR OUT OF THE
HIGH OVER THE AREA.

BIG CHANGES FOR SUNDAY HOWEVER...AS A SYSTEM EJECTING INTO THE
CENTRAL PLAINS PULLS A MORE MOIST AIRMASS...WITH SOME GULF OF MEX
MOISTURE...NORTHWARD INTO THE AREA. A MESS OF WINTRY PCPN TYPES
LOOKS TO SPREAD ACROSS THE TAF SITES DURING THE MID MORNING HOURS OF
SUN...ALONG WITH CIGS/VSBYS BECOMING MVFR/IFR. PERIODS OF -SN/PL/
-FZRA LOOK TO IMPACT THE TAF SITES AFTER 15Z SUNDAY INTO SUN
EVENING...WITH ACCUMULATIONS OF SNOW/SLEET/ICING ON THE AIRFIELDS.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
413 AM CST SAT JAN 26 2013

WI...WINTER STORM WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
     FOR WIZ029-032>034-041>044-053>055-061.

MN...WINTER STORM WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
     FOR MNZ079-086>088-094>096.

IA...WINTER STORM WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
     FOR IAZ008>011-018-019-029-030.


&&

$$

SHORT TERM...AJ
LONG TERM....AJ
AVIATION.....RRS










AREA FORECAST DISCUSSION

NWS LA CROSSE WI

 413 AM CST SAT JAN 26 2013

.SHORT TERM...TODAY THROUGH MONDAY NIGHT
413 AM CST SAT JAN 26 2013

MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES...TYPES AND
AMOUNTS FOR SUNDAY AND SUNDAY NIGHT.

CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED TROUGHING OFF THE PACIFIC NORTHWEST COAST...AN UPPER LOW NEAR
SAN DIEGO CA...RIDGING PROGRESSING INTO THE NORTHERN PLAINS...AND
TROUGHING FROM SOUTHEAST CANADA INTO NEW ENGLAND. THE FORECAST AREA
LIES IN THE SUBSIDENT PORTION AHEAD OF THE UPPER RIDGING...RESULTING
IN DRYING AND HIGH PRESSURE AT THE SURFACE. 00Z MPX SOUNDING SHOWED
A LOT OF DRY AIR ABOVE 800MB...WITH A PRECIPITABLE WATER OF 0.17
INCHES OVERALL. SATELLITE IMAGERY DEPICTS MAINLY CLEAR SKIES OVER
THE FORECAST AREA. AIRMASS ASSOCIATED WITH THE HIGH PRESSURE AREA
WAS ALSO RELATIVELY CHILLY WITH A 925MB TEMP OF -17C AT MPX.
COMBINATION OF THE CLEAR SKIES...DIMINISHING WINDS AND THE CHILLY
AIR HAS ALLOWED TEMPERATURES TO DROP INTO THE SINGLE DIGITS ABOVE
ZERO. TO THE NORTHWEST...MID AND HIGH CLOUDS WERE STREAMING ACROSS
NORTH DAKOTA AND NORTHWEST MN...ASSOCIATED WITH PACIFIC MOISTURE ON
WATER VAPOR BECOMING ENHANCED BY UPPER JET FORCING...AS WELL AS WARM
ADVECTION. WELL TO THE SOUTH...AN AREA OF PRECIPITABLE WATER VALUES
OF 0.8 INCHES AND HIGHER WAS PRESENT ACROSS MUCH OF TEXAS AND
LOUIS ANA...WELL DOWNSTREAM OF THE SAN DIEGO UPPER LOW.

TODAY AND TONIGHT...MODELS SHOW THE TROUGHING JUST OFF THE PACIFIC
NORTHWEST DIGGING INTO NORTHERN CALIFORNIA. ALTHOUGH THIS IS QUITE
FAR AWAY FROM HERE...THERE ARE NUMEROUS IMPACTS FROM IT. THE FIRST
IS TO KEEP PUSHING THE RIDGING COMING INTO THE NORTHERN PLAINS
EASTWARD...WITH ITS RIDGE AXIS PROGGED TO BE CENTERED OVER THE
FORECAST AREA AT 12Z SUNDAY. WARMER AIR WILL ACCOMPANY THE RIDGE...
WITH 925MB TEMPS CLIMBING TO -6 TO -10C BY 00Z AND -2 TO -5C BY 12Z
SUNDAY. THE SECOND IMPACT IS TO EJECT AND POSSIBLY SHEAR OUT THE SAN
DIEGO CA UPPER LOW...LIFTING IT UP TO AROUND GOODLAND KS BY 12Z
SUNDAY. AS THIS UPPER LOW APPROACHES THE CENTRAL PLAINS TONIGHT...A
LOW LEVEL JET DEVELOPS...PULLING THE MOISTURE SEEN ACROSS TEXAS
NORTHWARD. AT 12Z SUNDAY...PRECIPITABLE WATER VALUES BETWEEN 0.8-1
INCHES ARE POSSIBLE AS FAR NORTH AS DES MOINES IA AND OMAHA
NE...WHICH ARE ALMOST 300 PERCENT ABOVE NORMAL. WITH SO MUCH
MOISTURE RUNNING INTO A DRY AND COLDER AIRMASS PRESENT HERE ACROSS
THE UPPER MIDWEST...LOW CLOUDS AND PRECIPITATION SHOULD EASILY
DEVELOP. 26.00Z NAM/GFS/ECMWF/CANADIAN/UKMET ARE ALL IN GOOD
AGREEMENT KEEPING ANY PRECIPITATION SOUTH OF THE AREA PRIOR TO 12Z.
NOTE...THOUGH...THAT BY 12Z...PRECIPITATION SHOULD BE PRESENT FROM
KANSAS CITY TO OMAHA AND DES MOINES. FULL SUN THIS MORNING FOLLOWED
BY FILTERED SUN THROUGH MID/HIGH CLOUDS IN THE AFTERNOON...COMBINED
WITH THE WARMER AIR MOVING IN AND LIMITED SNOW ON THE GROUND...
SHOULD ALLOW TEMPERATURES TO CLIMB INTO THE LOW TO MID 20S. CLOUDS
FURTHER INCREASE TONIGHT...AND WITH WINDS PICKING UP ADVECTING
WARMER/MOIST AIR IN...THINK TEMPERATURES WILL FALL JUST A LITTLE IN
THE EVENING THEN MOSTLY HOLD STEADY OR RISE. FINAL NOTE ABOUT THE
CLOUD INCREASE TONIGHT...BOTH THE GFS AND REGIONAL CANADIAN PRODUCE
A LITTLE LIGHT SNOW ACROSS TAYLOR/CLARK COUNTIES FROM THE MID CLOUDS
THIS EVENING. ADDED SOME FLURRIES FOR NOW...GIVEN DRY WEATHER
SIGNALED BY OTHER MODELS.

SUNDAY AND SUNDAY NIGHT...THE TROUGHING DIGGING INTO NORTHERN
CALIFORNIA IS FORECAST TO DIG EVEN MORE DURING THIS PERIOD...AIDED
TOO BY A POTENT SHORTWAVE DROPPING THROUGH THE PACIFIC NORTHWEST.
THE RESULT BY 12Z MONDAY IS A FULL-FLEDGED TROUGH OVER THE WESTERN
1/3 OF THE U.S. IN RESPONSE...500MB HEIGHTS RISE DOWNSTREAM ACROSS
THE REST OF THE U.S.. THIS WILL CAUSE THE SHEARING OUT UPPER LOW
NEAR GOODLAND KS AT 12Z TO LIFT UP INTO THE FORECAST AREA BY 00Z
MONDAY. MODELS STILL DIFFER A BIT ON STRENGTH...BUT THE GENERAL
CONSENSUS IS THAT THE PRECIPITATION THAT DEVELOPS TONIGHT AROUND THE
KC...OMAHA AND DES MOINES AREAS WILL END UP TRANSLATING NORTHEAST
WITH THE SHEARING OUT UPPER LOW...IMPACTING THE FORECAST AREA. GOOD
SETUP FOR PRECIPITATION AS THE SURGE OF HIGH PRECIPITABLE WATER (FOR
THIS TIME OF YEAR) COMBINES WITH ISENTROPIC LIFT AND DPVA FROM THE
SHORTWAVE. REALLY GOOD AGREEMENT EXISTS NOW THAT MUCH OF THE AREA
BETWEEN 18Z SUNDAY AND 06Z MONDAY WILL SEE PRECIPITATION. IN
FACT...EVEN THE EXPECTED AMOUNTS BETWEEN THE 26.00Z
GFS/UKMET/ECMWF/CANADIAN...26.06Z NAM AND 26.03Z SREF ARE ALL REALLY
CLOSE...IN THE 0.25-0.6 RANGE...AND AGAIN MUCH OF THIS FALLING
DURING THAT 18Z SUN - 06Z MON. THE HIGHEST MAXIMUM HAS SHIFTED
NORTH...AFFECTING THE SOUTHEAST HALF OF THE FORECAST AREA INTO
NORTHERN ILLINOIS. GIVEN THE GREAT MODEL AGREEMENT...HAVE RAISED
PRECIPITATION CHANCES EVEN MORE. IT IS INTERESTING SCENARIO WITH
REGARDS TO PRECIPITATION TYPE. INITIALLY THERE IS SOME DRY AIR TO
OVERCOME WHILE WARM ADVECTION IS TAKING PLACE. THIS FAVORS MORE OF
FREEZING RAIN/SLEET AT THE ONSET...TRANSITIONING TO SLEET/SNOW
QUICKLY AS DYNAMIC COOLING TAKES OVER. YOU CAN SEE THIS NICELY IN
850MB TEMPS FROM THE MODELS. AS TIME PROGRESSES THROUGH THE
AFTERNOON AND EVENING...EVENTUALLY THE WARM AIR STARTS SPREADING
NORTH THROUGH THE AREA...CAUSING THE SNOW OR SLEET TO TRANSITION TO
FREEZING RAIN...ESPECIALLY SOUTH OF I-90. THEN...TO MAKE MATTERS
WORSE...THE ICE BEGINS TO LEAVE THE CLOUDS...LEAVING WHAT WILL
PROBABLY BE A FREEZING DRIZZLE AFTER MIDNIGHT. IN SUMMARY...A MESS.
COULD REALLY SEE A DECENT AMOUNT OF SLEET IN THIS EVENT...ESPECIALLY
ALONG/SOUTH OF I-90...SINCE THE BALANCE OF COOLING FROM
PRECIPITATION AND THE WARM ADVECTION KEEPS THE MAX TEMPERATURE ALOFT
IN THE 1-3C RANGE. GIVEN THAT WE COULD HAVE VARIOUS PRECIPITATION
TYPES EXCEEDING WARNING CRITERIA...AS WELL AS THE MODEL TRENDS NORTH
WITH THE MAX QPF...HAVE ISSUED A WINTER STORM WATCH EVERYWHERE
EXCEPT FOR TAYLOR WHICH LOOKS TOO FAR NORTH TO WARRANT A WATCH AT
THIS TIME. ON A SIDE NOTE...AFTER THE PRECIPITATION DIMINISHES TO
DRIZZLE...SETUP LOOKS FAVORABLE FOR FOG FORMATION. RECENT
PRECIPITATION PLUS DRYING ALOFT...LIGHT WINDS AND COLD GROUND ALL
SPELL FOG. ADDED AREAS OF FOG TO THE FORECAST AFTER MIDNIGHT SUNDAY
NIGHT.

MONDAY AND MONDAY NIGHT...MODELS SHOW THAT THE WESTERN TROUGH SLIDES
SLOWLY EASTWARD DURING THIS PERIOD...WITH A NEW LOW PRESSURE AREA
DEVELOPING OVER THE CENTRAL PLAINS. SUBSIDENCE IN THE WAKE OF THE
SUNDAY/SUNDAY NIGHT SYSTEM WILL LEAVE THE AREA DRY FOR MONDAY. NOTE
THAT THERE IS TRAPPED MOISTURE BELOW THE SUBSIDENCE INVERSION...BUT
26.00Z GFS/NAM SOUNDINGS DO NOT DEPICT ANY LIFT WITHIN THIS CLOUD
LAYER. THUS...THE SMALL PRECIPITATION CHANCES WERE REMOVED.
HOWEVER...FOG STILL LOOKS LIKE A GOOD BET FOR THE MORNING. SREF
VISIBILITY PROGS FOR LESS THAN 1 MILE ARE QUITE IMPRESSIVE AT 12Z
MONDAY WHEN LOOKING AT A REGIONAL PERSPECTIVE. WITH THE
PRECIPITATION SHUT OFF ON MONDAY...925MB TEMPS ARE REALLY ALLOWED TO
WARM...CLIMBING TO 0-4C BY 00Z TUESDAY. THUS...MOST LOCATIONS SHOULD
SEE HIGHS POP ABOVE FREEZING EVEN DESPITE THE CLOUDS. IN FACT...FAR
SOUTHERN AREAS COULD GET CLOSE TO 40. A NEW ROUND OF ISENTROPIC LIFT
STARTS UP MONDAY NIGHT AS THE LOW PRESSURE SYSTEM FORMS OVER THE
CENTRAL PLAINS. THERE ARE DIFFERENCES IN THE AMOUNT OF LIFT...BUT
THERE SHOULD BE ENOUGH TO SPREAD AT LEAST SOME LIGHT QPF ACROSS THE
AREA. GIVEN THAT MODEL FORECASTS HAVE THE NEAR SURFACE AIR COLD
ADVECTING WHILE THE AIR ALOFT SAY AT 850MB STAYS WARM (TEMPS ABOVE
2C)...CONCERNED THAT WE COULD END UP WITH FREEZING RAIN AND THUS
ADDED IT TO THE FORECAST.

.LONG TERM...TUESDAY THROUGH FRIDAY NIGHT
413 AM CST SAT JAN 26 2013

THE TWO BIG HIGHLIGHTS HERE ARE THE CENTRAL PLAINS SYSTEM FROM
MONDAY NIGHT AND THE CONSISTENT SURGE OF ARCTIC AIR PROGGED TOWARDS
THE MIDDLE OF THE WEEK. MODELS HAVE REALLY CHANGED THEIR TUNE FROM
YESTERDAY...NO LONGER CUTTING OFF THE SOUTHERN PORTION OF THE
WESTERN TROUGH. NOW THE WESTERN TROUGH IS SUGGESTED BY PRETTY MUCH
EVERY MODEL TO PROGRESS EASTWARD. AS IT DOES...THE CENTRAL PLAINS
LOW WILL LIFT NORTHEAST. THE BIG QUESTION MARK IS GOING TO BE
WATCHING HOW STRONG THIS LOW IS...WHICH DEPENDS ON HOW QUICK ARCTIC
AIR CAN COME DOWN INTO THE NORTHERN PLAINS. THE NEW 26.06Z GFS AND
TO SOME DEGREE THE 26.00Z CANADIAN PHASE THE TWO TOGETHER...
RESULTING IN A DEEP LOW. HOWEVER...THE ECMWF MAINTAINS A MORE
POSITIVELY TILTED LOOK...THUS A WEAKER LOW AND MUCH LESS QPF AND
WIND. NONETHELESS...CHANCES OF PRECIPITATION ARE REQUIRED FOR
TUESDAY THROUGH WEDNESDAY FOR THE BACK SIDE OF THE SYSTEM. IT IS
POSSIBLE TUESDAY WE COULD STILL BE DEALING WITH SNOW...RAIN...SLEET
AND FREEZING RAIN...BUT FOR NOW HAVE KEPT IT TO RAIN/SNOW. ARCTIC
AIR THEN RUSHES IN FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. 850MB
TEMPS PLUMMET TO -20 TO -24C. HIGH PRESSURE BUILDS IN FOR FRIDAY
WITH PERHAPS A NORTHWEST FLOW SYSTEM APPROACHING THE AREA FRIDAY
NIGHT.

&&

.AVIATION...
1115 PM CST FRI JAN 25 2013

HIGH PRESSURE WAS BUILDING IN FROM THE NORTHERN PLAINS...RESULTING
IN SKC AND A DECREASING WIND TREND. THE HIGH EXITS FAIRLY QUICKLY
EAST ON SAT THOUGH...WITH HIGH/MID LEVEL CLOUDS ON THE INCREASE FROM
THE WEST IN THE AFTERNOON. LIGHT WINDS OVERNIGHT WILL BECOME
EAST/SOUTHEAST ON SAT...BUT REMAIN LIGHT UNTIL LATER IN THE DAY. AN
INCREASING PRESSURE GRADIENT POST THE HIGH WILL KEEP WINDS UP SAT
NIGHT...ESPECIALLY AT KRST.

LOOKING AHEAD TO SUNDAY...A MESS OF WINTRY PCPN TYPES IS BECOMING
MORE LIKELY AS AN UPPER LEVEL SHORTWAVE TROUGH CHURNS ACROSS THE
REGION. PERIODS OF -SN/IP/FZRA WILL ACCOMPANY THIS SYSTEM...ALTHOUGH
THERE IS STILL UNCERTAINTY IN WHERE THE SYSTEM WILL MOVE...AND THUS
WHERE THE GREATER THREAT FOR WHICH PTYPE WILL LIE.

DEFINITELY A SYSTEM THAT BEARS A CLOSE WATCH AS IT COULD/WOULD
HAVE SIGNIFICANT AVIATION IMPACTS.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
413 AM CST SAT JAN 26 2013

WI...WINTER STORM WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
     FOR WIZ029-032>034-041>044-053>055-061.

MN...WINTER STORM WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
     FOR MNZ079-086>088-094>096.

IA...WINTER STORM WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
     FOR IAZ008>011-018-019-029-030.


&&

$$

SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK






AREA FORECAST DISCUSSION

NWS CHEYENNE WY

 406 AM MST SAT JAN 26 2013

.UPDATE...FOR 26/12Z TAF ISSUANCE...
SOME SCATTERED LOW CLOUDS HAVE BEEN OBSERVED AROUND KRWL EARLY
THIS MORNING. EXPECT VFR CONDITIONS AT KRWL BUT SOME LOWER CIGS IN
THE AREA THROUGH 18Z. ALL OTHER AERODROMES SHOULD SEE VFR
CONDITIONS NEXT 24 HOURS.

&&

.PREV DISCUSSION... /ISSUED 303 AM MST SAT JAN 26 2013/

SHORT TERM...SATURDAY THROUGH SUNDAY NIGHT...
AT 06Z SURFACE ANALYSIS SHOWED STRONG HIGH PRESSURE OVER MINNESOTA
AND A LOW PRESSURE CENTER OVER NORTHWEST MONTANA WITH A LEE SIDE
TROUGH/WARM FRONT EXTENDING FROM MONTANA ACROSS EASTERN WYOMING
AND ON SOUTHWARD INTO EASTERN COLORADO.

UPPER AIR ANALYSIS SHOWED WEAK RIDGE OVER NORTHERN ROCKIES WITH
SHORT WAVE OBSERVED AT BOTH 5/7H CROSSING WYOMING. TWO SEPARATE
SYSTEMS ANALYZED ONE OVER THE PACIFIC NORTHWEST WITH HEIGHT FALLS
GREATER THAN 50 METERS MOVING INTO PACIFIC NORTHWEST AND ANOTHER
MOVING INTO SOUTHERN CALIFORNIA.

MODELS IN DECENT AGREEMENT SHOWING A PROGRESSIVE PATTERN FOR THE
WESTERN U.S. THE SYSTEM WHICH INITIALLY WILL BE MORE OF AN
INTEREST TO OUR CWA WILL BE SOUTHERN ONE WHICH WILL PRODUCE
SOUTHWEST FLOW FOR THE AREA AND ADVECT SOME MID AND HIGH LEVEL
MOISTURE INTO THE AREA. WITH THIS PATTERN HAVE CONTINUED THE IDEA
OF DECENT CHANCES OF LIGHT SNOW IN THE HIGHER ELEVATIONS OF THE
CWA. TO THE EAST OF THE MOUNTAINS ABOVE NORMAL TEMPERATURES WILL
BE OBSERVED.

BY SUNDAY THE UPPER TROUGH OVER THE PACIFIC NORTHWEST WILL BE THE
SYSTEM TO KEEP AN EYE ON AS IT WILL AMPLIFY AND SLOWLY MOVE EAST.
THIS PATTERN WILL ALLOW FOR MORE SOUTHWESTERLY FLOW ALOFT AND KEEP
A CHANCE FOR SNOW IN THE MOUNTAINS AND MILD TEMPERATURES ON THE
PLAINS.

OUTSIDE THE HIGHER ELEVATIONS CHANCES OF PRECIPITATION WILL REMAIN
LOW THROUGH THE END OF THE SHORT TERM.

LONG TERM...MONDAY THROUGH FRIDAY...
00Z GFS/ECMWF SOLUTIONS STILL DIFFER SOMEWHAT WITH RESPECT TO THE
UPPER TROUGH IMPACTING THE ROCKIES AND GREAT PLAINS DURING THE
FIRST HALF OF THE WEEK. THE ECMWF CONTINUES TO SHOW A UPPER LOW
TRACKING ACROSS THE SOUTHWEST CONUS. A SURFACE LOW AND COLD FRONT
SETTLE SOUTHEAST THROUGH THE CWA MONDAY. QPFS SHOW MOST OF THE
PRECIPITATION PREVAILING OVER THE MOUNTAINS AND EAST CENTRAL
WYOMING MONDAY MORNING...SPREADING SOUTH AND EAST ACROSS THE REST
OF THE CWA MONDAY NIGHT. PRECIPITATION WILL BEGIN AS LIGHT RAIN
OVER SOUTHEAST WYOMING AND SOUTHERN NEBRASKA PANHANDLE...WITH A
RAIN/SNOW MIX TO THE NORTH AND LIGHT SNOW ALONG AND WEST OF THE
LARAMIE RANGE. EXPECT ALL SNOW MONDAY NIGHT AND TUESDAY...WITH
LIGHT ACCUMULATIONS. HIGH TEMPERATURES MONDAY WILL BE IN THE 40S
TO MID 50S FOR SOUTHEAST WYOMING AND SOUTHERN PANHANDLE...WITH
20S AND 30S ELSEWHERE. COLDER TEMPERATURES WILL OVERSPREAD THE
CWA TUESDAY WITH HIGHS FROM THE TEENS AND 20S ALONG AND WEST
OF THE LARAMIE RANGE...TO THE 30S ELSEWHERE.

UPPER RIDGING OVER THE EASTERN PACIFIC AND MEAN UPPER TROUGH
OVER THE GREAT LAKES AND MIDWEST WILL RESULT IN NORTHWEST FLOW
ALOFT FOR THE LATTER HALF OF THE WEEK. EMBEDDED WITHIN THE
FLOW WILL BE A COUPLE OF SHORTWAVES PASSING THROUGH. ONE WILL
IMPACT THE MOUNTAINS WEDNESDAY NIGHT AND THURSDAY...FOLLOWED
CLOSELY BY ANOTHER FRIDAY. MODELS DEPICT LIGHT QPF AMOUNTS
IN THESE AREAS...WHILE THE PLAINS CONTINUE DRY. AFTER A SEASONABLY
COOL WEDNESDAY...TEMPERATURES MODERATE TO ABOVE NORMAL THURSDAY
AND FRIDAY OVER SOUTHEAST WYOMING AND SOUTHERN PANHANDLE. AREAS
OUT WEST WILL REMAIN CHILLY WITH HIGHS IN THE 20S AND 30S.
WESTERLY WINDS WILL BE BREEZY EACH DAY...WITH GUSTS UP TO 40 MPH
IN AND NEAR THE MOUNTAINS.

AVIATION...SOME LOWER CLOUDS BEING OBSERVED EARLY THIS MORNING IN
SOUTHERN CARBON COUNTY AND THE HRRR HINTS THAT SOME OF THESE LOW
CLOUDS COULD MOVE INTO THE RAWLINS AREA BETWEEN 12-18Z. OTHERWISE
VFR CONDITIONS EXPECTED AT ALL AERODROMES.

FIRE WEATHER...NO FIRE WEATHER CONCERNS AT THIS TIME. WARM
TEMPERATURES OUTSIDE OF THE HIGHER ELEVATIONS THROUGH THE WEEKEND.
SLIGHT CHANCE OF LIGHT SNOW IN THE MOUNTAINS NEXT COUPLE OF DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.

&&

$$

SHORT TERM/FIRE WEATHER/AVIATION...GRIFFITH
LONG TERM...JAMSKI





AREA FORECAST DISCUSSION

NWS CHEYENNE WY

 303 AM MST SAT JAN 26 2013

.SHORT TERM...SATURDAY THROUGH SUNDAY NIGHT...
AT 06Z SURFACE ANALYSIS SHOWED STRONG HIGH PRESSURE OVER MINNESOTA
AND A LOW PRESSURE CENTER OVER NORTHWEST MONTANA WITH A LEE SIDE
TROUGH/WARM FRONT EXTENDING FROM MONTANA ACROSS EASTERN WYOMING
AND ON SOUTHWARD INTO EASTERN COLORADO.

UPPER AIR ANALYSIS SHOWED WEAK RIDGE OVER NORTHERN ROCKIES WITH
SHORT WAVE OBSERVED AT BOTH 5/7H CROSSING WYOMING. TWO SEPARATE
SYSTEMS ANALYZED ONE OVER THE PACIFIC NORTHWEST WITH HEIGHT FALLS
GREATER THAN 50 METERS MOVING INTO PACIFIC NORTHWEST AND ANOTHER
MOVING INTO SOUTHERN CALIFORNIA.

MODELS IN DECENT AGREEMENT SHOWING A PROGRESSIVE PATTERN FOR THE
WESTERN U.S. THE SYSTEM WHICH INITIALLY WILL BE MORE OF AN
INTEREST TO OUR CWA WILL BE SOUTHERN ONE WHICH WILL PRODUCE
SOUTHWEST FLOW FOR THE AREA AND ADVECT SOME MID AND HIGH LEVEL
MOISTURE INTO THE AREA. WITH THIS PATTERN HAVE CONTINUED THE IDEA
OF DECENT CHANCES OF LIGHT SNOW IN THE HIGHER ELEVATIONS OF THE
CWA. TO THE EAST OF THE MOUNTAINS ABOVE NORMAL TEMPERATURES WILL
BE OBSERVED.

BY SUNDAY THE UPPER TROUGH OVER THE PACIFIC NORTHWEST WILL BE THE
SYSTEM TO KEEP AN EYE ON AS IT WILL AMPLIFY AND SLOWLY MOVE EAST.
THIS PATTERN WILL ALLOW FOR MORE SOUTHWESTERLY FLOW ALOFT AND KEEP
A CHANCE FOR SNOW IN THE MOUNTAINS AND MILD TEMPERATURES ON THE
PLAINS.

OUTSIDE THE HIGHER ELEVATIONS CHANCES OF PRECIPITATION WILL REMAIN
LOW THROUGH THE END OF THE SHORT TERM.

.LONG TERM...MONDAY THROUGH FRIDAY...
00Z GFS/ECMWF SOLUTIONS STILL DIFFER SOMEWHAT WITH RESPECT TO THE
UPPER TROUGH IMPACTING THE ROCKIES AND GREAT PLAINS DURING THE
FIRST HALF OF THE WEEK. THE ECMWF CONTINUES TO SHOW A UPPER LOW
TRACKING ACROSS THE SOUTHWEST CONUS. A SURFACE LOW AND COLD FRONT
SETTLE SOUTHEAST THROUGH THE CWA MONDAY. QPFS SHOW MOST OF THE
PRECIPITATION PREVAILING OVER THE MOUNTAINS AND EAST CENTRAL
WYOMING MONDAY MORNING...SPREADING SOUTH AND EAST ACROSS THE REST
OF THE CWA MONDAY NIGHT. PRECIPITATION WILL BEGIN AS LIGHT RAIN
OVER SOUTHEAST WYOMING AND SOUTHERN NEBRASKA PANHANDLE...WITH A
RAIN/SNOW MIX TO THE NORTH AND LIGHT SNOW ALONG AND WEST OF THE
LARAMIE RANGE. EXPECT ALL SNOW MONDAY NIGHT AND TUESDAY...WITH
LIGHT ACCUMULATIONS. HIGH TEMPERATURES MONDAY WILL BE IN THE 40S
TO MID 50S FOR SOUTHEAST WYOMING AND SOUTHERN PANHANDLE...WITH
20S AND 30S ELSEWHERE. COLDER TEMPERATURES WILL OVERSPREAD THE
CWA TUESDAY WITH HIGHS FROM THE TEENS AND 20S ALONG AND WEST
OF THE LARAMIE RANGE...TO THE 30S ELSEWHERE.

UPPER RIDGING OVER THE EASTERN PACIFIC AND MEAN UPPER TROUGH
OVER THE GREAT LAKES AND MIDWEST WILL RESULT IN NORTHWEST FLOW
ALOFT FOR THE LATTER HALF OF THE WEEK. EMBEDDED WITHIN THE
FLOW WILL BE A COUPLE OF SHORTWAVES PASSING THROUGH. ONE WILL
IMPACT THE MOUNTAINS WEDNESDAY NIGHT AND THURSDAY...FOLLOWED
CLOSELY BY ANOTHER FRIDAY. MODELS DEPICT LIGHT QPF AMOUNTS
IN THESE AREAS...WHILE THE PLAINS CONTINUE DRY. AFTER A SEASONABLY
COOL WEDNESDAY...TEMPERATURES MODERATE TO ABOVE NORMAL THURSDAY
AND FRIDAY OVER SOUTHEAST WYOMING AND SOUTHERN PANHANDLE. AREAS
OUT WEST WILL REMAIN CHILLY WITH HIGHS IN THE 20S AND 30S.
WESTERLY WINDS WILL BE BREEZY EACH DAY...WITH GUSTS UP TO 40 MPH
IN AND NEAR THE MOUNTAINS.

&&

.AVIATION...12Z TAF ISSUANCE...SOME LOWER CLOUDS BEING OBSERVED
EARLY THIS MORNING IN SOUTHERN CARBON COUNTY AND THE HRRR HINTS
THAT SOME OF THESE LOW CLOUDS COULD MOVE INTO THE RAWLINS AREA
BETWEEN 12-18Z. OTHERWISE VFR CONDITIONS EXPECTED AT ALL
AERODROMES.

&&

.FIRE WEATHER...NO FIRE WEATHER CONCERNS AT THIS TIME. WARM
TEMPERATURES OUTSIDE OF THE HIGHER ELEVATIONS THROUGH THE WEEKEND.
SLIGHT CHANCE OF LIGHT SNOW IN THE MOUNTAINS NEXT COUPLE OF DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.

&&

$$

SHORT TERM/AVIATION/FIRE WEATHER...GRIFFITH
LONG TERM...JAMSKI






AREA FORECAST DISCUSSION

NWS SACRAMENTO CA

 919 AM PST SAT JAN 26 2013

.SHORT TERM DISCUSSION...

TROUGH CONTINUES OVER THE WEST COAST AND EASTERN PACIFIC. SEVERAL
DISTURBANCES ARE ROTATING THROUGH THE TROUGH. THE NEXT OF WHICH IS
A FEW HUNDRED MILES WEST OF EUREKA AND WILL DROP SOUTHEAST THROUGH
NORCAL DURING THE NEXT 24 HOURS. THERE WILL BE ENOUGH INSTABILITY
FOR A FEW SHOWERS...MAINLY OVER THE MOUNTAINS. THIS SYSTEM LACKS
MOISTURE AND QPF VALUES WILL BE GENERALLY LESS THAN A QUARTER OF
AN INCH. SNOW LEVELS WILL START OUT ABOVE 5000 FEET...BUT FALL TO
AROUND 2500 FEET OVERNIGHT. SNOWFALL WILL BE LIGHT WITH LESS THAN
3 INCHES OVER MOST MOUNTAIN AREAS.

AREAS OF FOG CONTINUE OVER MANY LOCATIONS THIS MORNING WITH
VISIBILITIES A QUARTER MILE OR LESS. THE FOG WILL LIFT AT MOST
SPOTS BY NOON AS ENOUGH MIXING OCCURS.


.PREVIOUS DISCUSSION...

WEAK FRONTAL BAND MOVING THROUGH NORCAL AT THIS TIME HAVING MINIMAL
IMPACT ON THE FORECAST AREA. GENERALLY ONLY THE NORTHERN PORTIONS OF
THE CWA ARE SEEING CLOUDINESS FROM THIS SYSTEM WITH ONLY VERY LIGHT
ECHOS INDICATED ON RADAR. FARTHER SOUTH...SKIES ARE CLEAR ENOUGH TO
ALLOW WIDESPREAD FOG FORMATION THROUGHOUT THE CENTRAL VALLEY AND
DELTA. SATELLITE FOG PRODUCT SHOWING MOST OF THE CENTRAL VALLEY
FILLING IN WITH THIS FOG AND LOW STRATUS ALTHOUGH SO FAR VISIBILITY
HAS KEPT FROM GOING DENSE. WILL NEED TO KEEP AN EYE OUT FOR NEED OF
A DENSE FOG ADVISORY LATER THIS MORNING. UPPER EASTERN PACIFIC
TROUGH FORECAST TO BEGIN PUSHING INTO NORTHWEST CORNER OF THE STATE
BY THIS AFTERNOON. COMBINATION OF LOW LEVEL MOISTURE AND OROGRAPHICS
WILL MAKE FOR A THREAT OF PRECIPITATION OVER THE MOUNTAINS BUT WITH
WEAK DYNAMICS GENERATED BY THE TROUGH...CAN NOT RULE OUT A SLIGHT
THREAT OF PRECIP ELSEWHERE. COLDER AIR WITHIN THE TROUGH WILL BEGIN
FILTERING INTO THE REGION THIS AFTERNOON BRINGING LOWER SNOW LEVELS
AND A COOLING TREND BUT MILD AIRMASS CURRENTLY IN PLACE WILL STILL
KEEP DAYTIME HIGHS TODAY A LITTLE ABOVE NORMAL. UPPER TROUGH AXIS
WILL PUSH INTO NORCAL TONIGHT BRINGING AN BETTER THREAT OF PRECIP TO
THE ENTIRE CWA. SNOW LEVELS WILL CONTINUE TO FALL DROPPING TO BELOW
2000 FEET BY SUNDAY MORNING. FORECAST MODELS STILL INDICATING THIS
TROUGH CONTAINS FAIRLY DRY AIR SO PRECIP AMOUNTS STILL FORECAST TO
BE ON THE MINIMAL SIDE. BY SUNDAY AFTERNOON...THE MAIN TROUGH AXIS
SHOULD BE EAST OF THE STATE PUTTING MOST OF NORCAL UNDER UPPER LEVEL
NORTHERLY FLOW. WEAK DISTURBANCES DROPPING SOUTHWARD IN THIS FLOW
COULD CONTINUE TO BRING A THREAT OF PRECIP ESPECIALLY OVER THE
EASTERN SIDE OF THE FORECAST AREA OVER THE SIERRA CASCADES. THE
NORTHERLY FLOW AND COOLER AIRMASS SHOULD PUSH DAYTIME HIGHS SUNDAY
DOWN TO BELOW NORMAL FOR THIS TIME OF YEAR. BY MONDAY...MID RANGE
MODELS ARE IN GOOD AGREEMENT IN SLIDING UPPER RIDGE EASTWARD OVER
THE WEST COAST. THIS SHOULD BRING A DRYING AND CLEARING TREND FROM
THE WEST ALTHOUGH SOME RAP AROUND MOISTURE AND CLOUDINESS WILL
LIKELY REMAIN OVER THE SIERRA. UPPER RIDGING AND CLEARING SKIES WILL
BRING A LIKELY RETURN OF VALLEY FOG BY TUESDAY MORNING. ONCE THIS
FOG CLEARS OUT...TUESDAY SHOULD SHAPE UP TO BE A FAIRLY CLEAR DAY
UNDER A BUILDING UPPER RIDGE WHICH IS FORECAST TO HOLD THROUGH MUCH
OF THE COMING WEEK.

.EXTENDED DISCUSSION (WEDNESDAY THROUGH SATURDAY)

MEDIUM RANGE MODELS SHOWING UPPER LEVEL RIDGING TO BE THE MAIN
SYNOPTIC FEATURE THROUGH THE EXTENDED PERIOD. RESULT WILL BE DRY
WEATHER TUESDAY THROUGH FRIDAY WITH SOME PATCHY NIGHT AND MORNING
VALLEY FOG. HIGH TEMPERATURES EXPECTED 5 TO 10 DEGREES ABOVE NORMAL.
LOCALLY BREEZY NORTH TO EAST WIND POSSIBLE...MAINLY OVER THE
NORTHERN AND EASTERN MOUNTAINS/FOOTHILLS...THROUGH THE EXTENDED
FORECAST PERIOD.


&&

.AVIATION...

POCKETS OF IFR/LIFR CIGS/VSBYS REMAIN IN FG/BR. LOW CLOUDS WITH
IFR/LIFR CONDITIONS ALSO CONTINUE IN THE SIERRA FOOTHILLS THROUGH THE
MORNING. CHANCE OF RAIN AND SNOW SHOWERS EXPECTED IN THE SIERRA
MOSTLY ABOVE 6000FT...LOWERING TO 3000 FEET BY TOMORROW AFTERNOON.
GENERALLY LIGHT WINDS EXPECTED THROUGH TOMORROW MORNING...EXCEPT
LOCAL STRONG SW GUSTS OVER SIERRA RIDGES TONIGHT. EK

&&

.STO WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING CARQUINEZ STRAIT
AND DELTA...CENTRAL SACRAMENTO VALLEY...MOTHERLODE...NORTHEAST
FOOTHILLS/SACRAMENTO VALLEY...NORTHERN SACRAMENTO VALLEY...
NORTHERN SAN JOAQUIN VALLEY...SOUTHERN SACRAMENTO VALLEY.

&&

$$








AREA FORECAST DISCUSSION

NWS GOODLAND KS

 149 PM MST SAT JAN 26 2013

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 135 PM MST SAT JAN 26 2013

LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW SHORTWAVE RIDGING ACROSS
THE SOUTHERN PLAINS WITH A SERIES OF SHORTWAVE TROUGHS OVER SOUTHERN
CALIFORNIA AND OFF THE PACIFIC NW COAST. THE FIRST OF THESE TROUGHS
OVER SOUTHERN CALIFORNIA WILL BE THE MAIN WEATHER PRODUCER FOR US
TONIGHT WITH MID-HIGH CLOUDS ALREADY INCREASING AHEAD OF THIS
FEATURE OVER COLORADO AND WESTERN KS.

GUIDANCE IN GENERAL AGREEMENT ON PRECIP SPREADING FROM THE WEST TO
THE EAST THROUGH THE EVENING HOURS...WITH BEST COVERAGE/CHANCES
ACROSS THE EAST/NORTHEAST AFTER MIDNIGHT AS A WARM FRONT MOVES NORTH
AND MOISTURE ADVECTION INCREASES. IM NOT AS CONFIDENT ABOUT COVERAGE
DURING THE EVENING WITH MOISTURE ADVECTION BELOW H7 MARGINAL UNTIL
06Z. NAM IS ADVERTISING DRY SLOT QUICKLY MOVING FROM THE W/SW LATE
THIS EVENING THROUGH SUNDAY MORNING...AND WITH STRONG DRY SLOT
ALREADY APPARENT ON WV IMAGERY THIS MAY BE REASONABLE. I HAVE
TRENDED POPS HIGHER ACROSS THE NORTHEAST AROUND 06-12Z...AND HAVE
DECREASED POPS QUICKER ACROSS THE SW DURING THIS SAME TIME PERIOD.
OVERALL QPF AMOUNTS SHOULD BE LIGHT...WITH HIGHEST TOTALS IN SW
NEBRASKA AND NORTH CENTRAL KS WHERE UP TO 0.10 INCHES OF LIQUID IS
POSSIBLE. AS WITH PREVIOUS FORECASTS I KEPT PRECIP TYPE ALL RAIN
WITH MODEL SOUNDINGS SUPPORTING ALL LIQUID...AND SURFACE
TEMPERATURES EXPECTED TO REMAIN ABOVE FREEZING WHERE PRECIP/CLOUD
COVER IS LINGERING AFTER MIDNIGHT. BELOW FREEZING TEMPS WILL BE
POSSIBLE IN THE W/SW WHERE SKIES WILL BE CLEARING...HOWEVER PRECIP
WILL BE OVER WITH AT THAT POINT. WITH INCREASING LOW LEVEL MOISTURE
ACROSS THE NORTH AND EAST WE COULD ALSO SEE PATCHY FOG DEVELOPMENT
LATE TONIGHT INTO SUNDAY MORNING BEFORE THE WARM FROM FINAL PUSHES
NORTH INTO CENTRAL NEBRASKA BEFORE 18Z...WITH DRY/STABLE CONDITIONS
EXPECTED THROUGH THE REST OF SUNDAY.

WITH CLEARING SKIES...AND 10-14C H85 TEMPS ADVECTING OVER THE CWA
FROM THE WEST WE SHOULD SEE ANOTHER MILD DAY WITH TEMPERATURES IN THE
MIDDLE 60S IN THE SOUTH TO THE LOW 50S NEAR MCCOOK WHERE CLOUD COVER
MAY LINGER LONGER INTO THE AFTERNOON.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 135 PM MST SAT JAN 26 2013

MUCH ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH MONDAY.
SYSTEM WILL MOVE THROUGH MONDAY NIGHT BRINGING A CHANCE OF LIGHT
SNOW AND COLDER TEMPERATURES. THERE COULD BE A BRIEF PERIOD OF
LIGHT RAIN AHEAD OF THE FRONT...BUT IT WILL QUICKLY CHANGE TO
SNOW. LIGHT SNOW OR FLURRIES COULD LINGER INTO TUESDAY...MAINLY IN
THE MORNING. TOTAL SNOW ACCUMULATIONS FOR MONDAY NIGHT THROUGH
TUESDAY CURRENTLY FORECAST TO BE AN INCH OR LESS. WIND DOES NOT
APPEAR THAT IT WILL BE A PROBLEM. THE REMAINDER OF THE PERIOD WILL
BE DOMINATED BY NORTHWEST FLOW ALOFT. GFS SHOWS SOME VERY LIGHT
SNOW OR FLURRIES WEDNESDAY NIGHT WITH SUBTLE SHORTWAVE IN THE
FLOW...OTHERWISE DRY. TEMPERATURES WILL SLOWLY REBOUND FROM THE
TUESDAY COOL DOWN...NEAR NORMAL WEDNESDAY AND THURSDAY THEN
SLIGHTLY ABOVE NORMAL FRIDAY AND SATURDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1033 AM MST SAT JAN 26 2013

PRIMARY AVIATION CONCERN WILL BE POTENTIAL RAIN TONIGHT AS
DISTURBANCE MOVES OVER PLAINS AND CIG/VIS IMPACTS AT EITHER KGLD
AND KMCK. BEST CHANCE OF RAINFALL AT EITHER TERMINAL IS AT KMCK
09-15Z PERIOD WHEN MVFR CIGS/VIS ARE EXPECTED AND IFR/LIFR
CONDITIONS MAY BE POSSIBLE WITH SATURATING LOW LEVELS. KGLD IS MORE
LIKELY TO SEE ONLY BRIEF RAINFALL...AND CHANCES ARE TOO LOW AT
THIS POINT TO PREVAIL MORE THAT VCSH IN TAFS. WITH DRIER AIR
EXPECTED AT KGLD...I AM EXPECTING VFR CONDITIONS TO PREVAIL. WINDS
ARE EXPECTED TO REMAIN LESS THAN 12KT AT EITHER TERMINAL...WITH
SOUTHERLY WINDS SHIFTING TO THE NORTHWEST SUNDAY MORNING.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

SHORT TERM...DR
LONG TERM...024
AVIATION...DR




AREA FORECAST DISCUSSION

NWS MARQUETTE MI

 555 PM EST SAT JAN 26 2013

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 421 PM EST SAT JAN 26 2013

LAKE EFFECT HAS BEEN GRADUALLY DIMINISHING THROUGH THE AFTERNOON
HOURS...AS THE NORTHERLY FLOW HAS SLOWED WITH HIGH PRESSURE MOVING
OVER THE CWA. STILL HAVE SOME LIGHT SNOW SHOWERS OVER THE NORTH
CENTRAL CWA...BUT EXPECT THEM TO END OR PUSH NORTH DURING THE LATE
AFTERNOON AND EARLY EVENING. OTHERWISE...A FAIRLY NICE AFTERNOON
WITH LIGHT WINDS AND TEMPERATURES AT OR SLIGHTLY BELOW NORMAL AS OF
3PM.

HIGH PRESSURE CENTERED OVER THE UPPER GREAT LAKES WILL SHIFT EAST
TONIGHT AS THE UPPER RIDGE BUILDS NORTHEAST INTO THE UPPER
MISSISSIPPI VALLEY. AS THIS OCCURS...BROAD H800-600 WARM AIR
ADVECTION CURRENTLY IN MINNESOTA AND STARTING TO MOVE INTO WESTERN
LAKE SUPERIOR WILL CONTINUE EAST ACROSS THE CWA TONIGHT. SO FAR
TODAY...HAVE ONLY SEEN A FEW OBS REPORTING SNOW SHOWERS FROM THIS
MID CLOUD DECK IN NORTHERN MN...WHICH WAS LIKELY HELD OFF BY DRY
H925-850 AIR SEEN ON 12Z KINL SOUNDING AND RUC SOUNDINGS IN THAT
AREA. LATEST MODELS DO TRY TO MOISTEN THE CENTRAL CWA TOWARDS
MIDNIGHT...AS THE STRONGER H925-850 WAA SLIDES EAST ALONG THE WI
BORDER. NOT LIKING HOW QUICKLY THINGS MOISTEN...BUT WITH THE IDEA IN
SEVERAL MODELS...WILL ADD SLIGHT CHANCES THERE. WILL KEEP THE BEST
POPS OVER THE NORTHERN HALF OF LAKE SUPERIOR WHERE THE LOWER LEVELS
WERE A LITTLE MORE MOIST AND THE MID LEVEL WAA WAS THE STRONGEST.
ALSO ADDED A MENTION OF FLURRIES TO AREAS SURROUNDING THE POPS TO
ACCOUNT FOR SOME SNOW MAKING IT THROUGH THE DRY AIR.

THE OTHER ITEM OF CONCERN HEADING INTO THE OVERNIGHT HOURS WILL BE
THE INCREASED MOISTENING OF THE LOWER LEVELS OFF LAKE MICHIGAN. AS
THIS OCCURS...THE H850 TEMPS WILL BE WARMING TOWARDS -10C
OVERNIGHT...SO DON/T EXPECT LAKE ENHANCEMENT TO GET TOO OUT OF
HAND. BUT WITH THE SNOW ALOFT FEEDING INTO THE LOWER LEVELS FORCING
THAT IS MAINLY BELOW -10C...EXPECT SNOW TO DEVELOP THERE. H925 WINDS
ARE FAVORABLE FOR SOUTHERN LUCE AND SOUTHEAST SCHOOLCRAFT...SO HAVE
INCREASED POPS INTO LOW END LIKELY VALUES FOR THOSE LOCATIONS
AND TAPERED IT OFF FAIRLY QUICKLY TO THE WEST. WITH SNOW RATIOS ON
THE LOW END...AROUND 10-14 TO 1 INITIALLY AND TRENDING
TOWARDS 8-1 SUNDAY MORNING...EXPECT ACCUMULATIONS TO BE FAIRLY LIGHT
IN THOSE AREAS WITH ONLY AN INCH OF ACCUMULATION. THE LAKE EFFECT
SHOULD DIMINISH LATER SUNDAY MORNING INTO THE EARLY AFTERNOON DUE TO
THE CONTINUED WARMING OF TEMPS ALOFT SHOVING INVERSION HEIGHTS TO
3KFT.

SUNDAY LOOKS TO BE FAIRLY QUIET...AS THE AREA IS BETWEEN THE
EXITING WARM AIR ADVECTION PRECIPITATION AND THE NEXT APPROACHING
SYSTEM FOR SUNDAY NIGHT. THE NEXT WAVE IS CURRENTLY OVER
SOUTHERN CALIFORNIA AND QUICKLY MOVES NORTHEAST AND
TOWARDS THE AREA TONIGHT AND SUNDAY. WITH THE INCREASED CONSISTENCY
IN THE MODELS...HAVE DELAYED THE START OF THE PRECIPITATION UNTIL
00Z AND LATER. THE LONG TERM DISCUSSION WILL COVER THIS SYSTEM IN
FURTHER DETAILS.

OTHERWISE...WILL SEE A GAP IN THE CLOUDS BEHIND THE WAA
CLOUDS DEPARTING IN THE MORNING AND THE INCREASING CLOUDS FROM THE
SOUTHWEST IN THE AFTERNOON. THINK THIS CLEARING WILL BE MOST LIKELY
OVER THE WEST HALF AND HAVE TRENDED TOWARDS PARTLY-MOSTLY SUNNY SKY
FOR PERIOD AROUND MID DAY. FARTHER EAST...NAM/GFS ARE HINTING AT
SOME LOWER CLOUDS DEVELOPING TONIGHT AND REMAINING THROUGH MUCH OF
SUNDAY. NOT OVERLY CONFIDENT ON THIS SOLUTION WITH THE DRY AIR
UPSTREAM...BUT WITH THE EXITING MID CLOUDS AND APPROACHING HIGH
CLOUDS...A PARTLY-MOSTLY CLOUDY FORECAST SEEMED WARRANTED.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 421 PM EST SAT JAN 26 2013

EARLY PORTION OF THE LONG TERM PERIOD SHOULD BE FAIRLY ACTIVE AS
PATTERN UNDERGOES SIGNIFICANT TRANSITIONS NEXT WEEK. CURRENT ERN
NAMERICA TROF IS IN THE PROCESS OF WEAKENING...AND IT WILL LIFT OUT
OVER THE NEXT COUPLE OF DAYS AS A TROF AMPLIFYING OVER THE WRN CONUS
FORCES DOWNSTREAM RIDGING OVER THE ERN CONUS INTO SE CANADA. THIS
WILL LEAD TO A SUBSTANTIAL WARMUP FOR THE UPPER LAKES. AS THE WRN
TROF THEN SHIFTS E...IT APPEARS PATTERN WILL RETURN TO SOME FORM OF
THE RECENT PATTERN WITH WRN RIDGING/ERN TROFFING. THIS WILL SUPPORT
A TREND BACK TO BLO NORMAL TEMPS FOR THE LAST HALF OF THE WEEK AND A
RETURN OF PERSISTENT LES OFF LAKE SUPERIOR. WHILE IT DOESN`T HAPPEN
TOO OFTEN...CONFIDENCE IN THE LATTER PORTION OF THE LONG TERM IS
MUCH MUCH HIGHER THAN THE EARLY PART. DURING THE EARLY PART...THERE
REMAINS CONSIDERABLE UNCERTAINTY IN THE EVOLUTION OF THE WRN TROF
THRU THE CNTRL INTO ERN CONUS. THAT UNCERTAINTY CENTERS AROUND
WHETHER THE PIECE OF ENERGY IN THE SRN PART OF THE WRN TROF LIFTS
OUT AND PHASES WITH ENERGY DROPPING SE OUT OF CANADA. MORE ON THAT
LATER.

BEGINNING SUN NIGHT...ATTENTION WILL BE ON THE SHORTWAVE THAT IS
CURRENTLY LIFTING NE ACROSS AZ IN RESPONSE TO TROF THAT IS NOW
AMPLIFYING ALONG THE W COAST. WAVE LOOKS VERY WELL-DEFINED ON WATER
VAPOR IMAGERY WITH AN ASSOCIATED PLUME OF PACIFIC MOISTURE. AS
SHORTWAVE CONTINUES TO LIFT NE...MODELS SHOW A NICE SHALLOW STREAM
OF MOISTURE GETTING TAPPED OFF THE GULF. SO...WITH THE SHALLOW
MOISTURE FEED...WAA/ISENTROPIC ASCENT AHEAD OF WAVE WILL LEAD TO AN
AREA OF PCPN DEVELOPING ACROSS THE CNTRL PLAINS AND THEN EXPANDING
AS IT SHIFTS INTO THE GREAT LAKES. PRECIPITABLE WATER ALSO INCREASES
TO 200-300PCT OF NORMAL. SO IF FORCING IS STRONG...MAY SEE SOME
DECENT PCPN AMOUNTS. OVERALL...MODELS ARE TRENDING SLIGHTLY MORE
DEFINED WITH SHORTWAVE WHICH LOOKS ON TRACK GIVEN CURRENT WATER
VAPOR IMAGERY AND DESPITE THE FACT THAT IT WILL BE WEAKENING AS IT
LIFTS NE THRU THE BUILDING LARGER SCALE RIDGE. MODELS ARE ALSO
TRENDING A LITTLE FARTHER N AND W WITH ASSOCIATED PCPN. NAM/REGIONAL
GEM REPRESENT THE THE NW SIDE OF THE 12Z MODEL RUNS WITH BOTH
SPREADING PCPN SQUARELY ACROSS UPPER MI. NAM HAS AMOUNTS FROM
0.25-0.6 INCHES WHILE THE GEM HAS 0.15-0.3 INCHES. ALTHOUGH A LITTLE
SKEPTICAL OF THESE MORE NW SOLUTIONS...TRENDS FROM REMAINING
GUIDANCE STILL SUPPORT CONTINUING TREND FROM PREVIOUS FCST TO BUMP
UP POPS FOR SUN NIGHT. PER 295K SFC...A HEALTHY PUSH OF ISENTROPIC
ASCENT IS INDICATED TO SPREAD INTO THE GREAT LAKES REGION WHICH SHOULD
LEAD TO A DECENT AREA OF PCPN. PTYPE MAY BE AN ISSUE AS 850MB TEMPS
RISE TO AROUND 0C SUN. HOWEVER...WITH WETBULB PROFILE BLO 0C...SEEMS
LIKELY THAT TEMP PROFILE WILL QUICKLY FALL SUBZERO DUE TO
EVAPORATIVE COOLING AS WELL AS DYNAMIC COOLING. PLAN FOR NOW WILL BE
TO UTILIZE JUST SNOW AS PTYPE SUN NIGHT. 295K SFC SHOWS MIXING
RATIOS AROUND 4G/KG...SUGGESTING POTENTIAL FOR UP TO 8 INCHES OF
SNOW WHERE MAX ASCENT OCCURS. SINCE DURATION OF PCPN WILL PROBABLY
BE ON THE ORDER 9HRS...HIGH END SNOW TOTALS COULD REACH 6 INCHES IF
MAX FORCING DOES SPREAD INTO UPPER MI. WILL CONTINUE TO PAINT THE
HIGHER PCPN AMOUNTS OVER THE SE FCST AREA WHERE SNOW AMOUNTS OF 2 TO
4 INCHES WILL BE INCLUDED FOR THIS FCST. MAY SEE 1-2 INCHES NW. ON
THE BACKSIDE OF SNOW AREA...PCPN MAY TRANSITION TO SOME -FZDZ SW TO
NE MON MORNING AS MID LEVEL MOISTURE PULLS OUT. THERE SHOULD THEN BE
A TREND TO DRY WEATHER DURING THE DAY MON.

OVER THE LAST FEW DAYS...THE BIGGEST UNCERTAINTY HAS BEEN THE
TUE/WED TIME PERIOD DUE TO THE CONSIDERABLE SPREAD OF SOLUTIONS
REGARDING THE EASTWARD PROGRESSION/EVOLUTION OF THE CURRENTLY
AMPLIFYING WRN CONUS TROF. MAIN POINTS OF UNCERTAINTY INVOLVE
WHETHER THE ENERGY IN THE BASE OF THE WRN TROF DROPS OUT AND HANGS
BACK OVER THE SW...OR IF IT DOES NOT...WILL IT LIFT NE AND PHASE
WITH ENERGY DROPPING SE TOWARD THE GREAT LAKES. THE ECMWF HAD
SEVERAL RUNS FAVORING THE IDEA OF DROPPING THE ENERGY OUT. IT IS NOW
TRENDING BACK TO KEEPING THE SRN PORTION PROGRESSIVE...BUT IT DOES
NOT LIFT ENERGY NE TO PHASE WITH THE NRN PORTION IN THE GREAT LAKES
REGION. THE GFS HAS HAD THE MOST RUNS FAVORING PHASING OF ENERGY IN
THE VCNTY OF THE GREAT LAKES WITH THE GLOBAL GEM/UKMET ALSO
GENERALLY LEANING IN THAT DIRECTION ON MOST RUNS. AGAIN...AS IN
PREVIOUS DAYS...THERE ARE A FEW GFS ENSEMBLES THAT HAVE A DEEP STORM
MOVING NE THRU THE UPPER LAKES REGION. AT THIS POINT...GIVEN THE
SPREAD OF SOLUTIONS...PARTICULARLY WITH REGARD TO THE ALWAYS
UNCERTAIN PHASING OF STREAMS AND LOCATIONS OF SUCH OCCURRENCE...
THERE IS NOT ENOUGH CONFIDENCE TO REALLY TREND INHERITED FCST MUCH
IN ANY DIRECTION. SO...AS HAS BEEN THE CASE IN RECENT DAYS...BEST
PATH WILL CONTINUE TO BE TO USE A CONSENSUS OF RECENT MODEL RUNS
UNTIL THE DETAILS ARE SORTED OUT. GIVEN THE WARMTH PUSHING INTO THE
AREA OVER THE NEXT FEW DAYS...MIXED PCPN COULD BE AN ISSUE...AND FOR
THIS FCST ISSUANCE WILL KEEP A MENTION OF A MIX...RANGING FROM
MOSTLY RAIN FOR A TIME SE TO MAINLY SNOW NW. DEPENDING ON TRACK OF
SFC LOW AND WHETHER IT DEEPENS SUBSTANTIALLY...THERE COULD BE A
TRANSITION TO SIGNIFICANT SNOW/BLSN LATER TUE INTO WED NEAR LAKE
SUPERIOR WHERE LAKE ENHANCEMENT/LES WILL GET UNDERWAY. LAKE SUPERIOR
LES WILL THEN BE THE RULE WED THRU FRI AS ARCTIC AIR SETTLES OVER
THE AREA (850MB TEMPS FALL TO -20 TO -25C). UTILIZED CATEGORICAL
POPS FOR THE USUAL AREAS FAVORED BY NW WINDS WED THRU FRI GIVEN VERY
HIGH CONFIDENCE IN LES. CLIPPER TYPE SYSTEM ARRIVING SAT MAY RESULT
IN -SN SPREADING INTO AREAS AWAY FROM LES.
&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 554 PM EST SAT JAN 26 2013

VFR CONDITIONS WILL CONTINUE AT ALL SITES THROUGH THE FORECAST
PERIOD. THERE COULD BE A BRIEF PERIOD OF -SHSN OR FLURRIES AT
KCMX/KSAW...BUT IT SHOULDN/T AFFECT VISIBILITIES OVERNIGHT. THESE
CLOUDS SHOULD PUSH EAST ON SUNDAY MORNING AND JUST LEAVE SOME
PASSING MID CLOUDS. DID PUT A MENTION OF SCATTERED LOW CLOUDS AT
KSAW TOMORROW MORNING...SINCE THE MODELS ARE HINTING AT THAT
POSSIBILITY. DID PUT IN A LOW CHANCE FOR SNOW LATE IN THE DAY FOR
IWD AS NEXT SYSTEM GETS CLOSER.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 421 PM EST SAT JAN 26 2013

HIGH PRESSURE CURRENTLY OVERHEAD WILL SHIFT EAST TONIGHT AND LEAD
TO INCREASING SOUTHERLY WINDS...BUT EXPECT GUSTS TO REMAIN BELOW
25KTS. WINDS WILL REMAIN BELOW 25KTS THROUGH THE FIRST COUPLE OF
DAYS OF THE UPCOMING WORK WEEK DUE TO WEAK PRESSURE GRADIENTS. A
LOW MOVING THROUGH THE GREAT LAKES ON TUESDAY AND THEN INCREASING
IN INTENSITY OVER EASTERN CANADA WILL PRODUCE INCREASING NORTHERLY
WINDS TO 30KTS TUESDAY NIGHT INTO WEDNESDAY. THIS...COMBINED WITH
COLDER AIR SURGING SOUTH...WILL LEAD TO FREEZING SPRAY FOR THE
MIDDLE AND END OF THE WORK WEEK.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...07
MARINE...SRF







AREA FORECAST DISCUSSION

NWS MARQUETTE MI

 423 PM EST SAT JAN 26 2013

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 421 PM EST SAT JAN 26 2013

LAKE EFFECT HAS BEEN GRADUALLY DIMINISHING THROUGH THE AFTERNOON
HOURS...AS THE NORTHERLY FLOW HAS SLOWED WITH HIGH PRESSURE MOVING
OVER THE CWA. STILL HAVE SOME LIGHT SNOW SHOWERS OVER THE NORTH
CENTRAL CWA...BUT EXPECT THEM TO END OR PUSH NORTH DURING THE LATE
AFTERNOON AND EARLY EVENING. OTHERWISE...A FAIRLY NICE AFTERNOON
WITH LIGHT WINDS AND TEMPERATURES AT OR SLIGHTLY BELOW NORMAL AS OF
3PM.

HIGH PRESSURE CENTERED OVER THE UPPER GREAT LAKES WILL SHIFT EAST
TONIGHT AS THE UPPER RIDGE BUILDS NORTHEAST INTO THE UPPER
MISSISSIPPI VALLEY. AS THIS OCCURS...BROAD H800-600 WARM AIR
ADVECTION CURRENTLY IN MINNESOTA AND STARTING TO MOVE INTO WESTERN
LAKE SUPERIOR WILL CONTINUE EAST ACROSS THE CWA TONIGHT. SO FAR
TODAY...HAVE ONLY SEEN A FEW OBS REPORTING SNOW SHOWERS FROM THIS
MID CLOUD DECK IN NORTHERN MN...WHICH WAS LIKELY HELD OFF BY DRY
H925-850 AIR SEEN ON 12Z KINL SOUNDING AND RUC SOUNDINGS IN THAT
AREA. LATEST MODELS DO TRY TO MOISTEN THE CENTRAL CWA TOWARDS
MIDNIGHT...AS THE STRONGER H925-850 WAA SLIDES EAST ALONG THE WI
BORDER. NOT LIKING HOW QUICKLY THINGS MOISTEN...BUT WITH THE IDEA IN
SEVERAL MODELS...WILL ADD SLIGHT CHANCES THERE. WILL KEEP THE BEST
POPS OVER THE NORTHERN HALF OF LAKE SUPERIOR WHERE THE LOWER LEVELS
WERE A LITTLE MORE MOIST AND THE MID LEVEL WAA WAS THE STRONGEST.
ALSO ADDED A MENTION OF FLURRIES TO AREAS SURROUNDING THE POPS TO
ACCOUNT FOR SOME SNOW MAKING IT THROUGH THE DRY AIR.

THE OTHER ITEM OF CONCERN HEADING INTO THE OVERNIGHT HOURS WILL BE
THE INCREASED MOISTENING OF THE LOWER LEVELS OFF LAKE MICHIGAN. AS
THIS OCCURS...THE H850 TEMPS WILL BE WARMING TOWARDS -10C
OVERNIGHT...SO DON/T EXPECT LAKE ENHANCEMENT TO GET TOO OUT OF
HAND. BUT WITH THE SNOW ALOFT FEEDING INTO THE LOWER LEVELS FORCING
THAT IS MAINLY BELOW -10C...EXPECT SNOW TO DEVELOP THERE. H925 WINDS
ARE FAVORABLE FOR SOUTHERN LUCE AND SOUTHEAST SCHOOLCRAFT...SO HAVE
INCREASED POPS INTO LOW END LIKELY VALUES FOR THOSE LOCATIONS
AND TAPERED IT OFF FAIRLY QUICKLY TO THE WEST. WITH SNOW RATIOS ON
THE LOW END...AROUND 10-14 TO 1 INITIALLY AND TRENDING
TOWARDS 8-1 SUNDAY MORNING...EXPECT ACCUMULATIONS TO BE FAIRLY LIGHT
IN THOSE AREAS WITH ONLY AN INCH OF ACCUMULATION. THE LAKE EFFECT
SHOULD DIMINISH LATER SUNDAY MORNING INTO THE EARLY AFTERNOON DUE TO
THE CONTINUED WARMING OF TEMPS ALOFT SHOVING INVERSION HEIGHTS TO
3KFT.

SUNDAY LOOKS TO BE FAIRLY QUIET...AS THE AREA IS BETWEEN THE
EXITING WARM AIR ADVECTION PRECIPITATION AND THE NEXT APPROACHING
SYSTEM FOR SUNDAY NIGHT. THE NEXT WAVE IS CURRENTLY OVER
SOUTHERN CALIFORNIA AND QUICKLY MOVES NORTHEAST AND
TOWARDS THE AREA TONIGHT AND SUNDAY. WITH THE INCREASED CONSISTENCY
IN THE MODELS...HAVE DELAYED THE START OF THE PRECIPITATION UNTIL
00Z AND LATER. THE LONG TERM DISCUSSION WILL COVER THIS SYSTEM IN
FURTHER DETAILS.

OTHERWISE...WILL SEE A GAP IN THE CLOUDS BEHIND THE WAA
CLOUDS DEPARTING IN THE MORNING AND THE INCREASING CLOUDS FROM THE
SOUTHWEST IN THE AFTERNOON. THINK THIS CLEARING WILL BE MOST LIKELY
OVER THE WEST HALF AND HAVE TRENDED TOWARDS PARTLY-MOSTLY SUNNY SKY
FOR PERIOD AROUND MID DAY. FARTHER EAST...NAM/GFS ARE HINTING AT
SOME LOWER CLOUDS DEVELOPING TONIGHT AND REMAINING THROUGH MUCH OF
SUNDAY. NOT OVERLY CONFIDENT ON THIS SOLUTION WITH THE DRY AIR
UPSTREAM...BUT WITH THE EXITING MID CLOUDS AND APPROACHING HIGH
CLOUDS...A PARTLY-MOSTLY CLOUDY FORECAST SEEMED WARRANTED.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 421 PM EST SAT JAN 26 2013

EARLY PORTION OF THE LONG TERM PERIOD SHOULD BE FAIRLY ACTIVE AS
PATTERN UNDERGOES SIGNIFICANT TRANSITIONS NEXT WEEK. CURRENT ERN
NAMERICA TROF IS IN THE PROCESS OF WEAKENING...AND IT WILL LIFT OUT
OVER THE NEXT COUPLE OF DAYS AS A TROF AMPLIFYING OVER THE WRN CONUS
FORCES DOWNSTREAM RIDGING OVER THE ERN CONUS INTO SE CANADA. THIS
WILL LEAD TO A SUBSTANTIAL WARMUP FOR THE UPPER LAKES. AS THE WRN
TROF THEN SHIFTS E...IT APPEARS PATTERN WILL RETURN TO SOME FORM OF
THE RECENT PATTERN WITH WRN RIDGING/ERN TROFFING. THIS WILL SUPPORT
A TREND BACK TO BLO NORMAL TEMPS FOR THE LAST HALF OF THE WEEK AND A
RETURN OF PERSISTENT LES OFF LAKE SUPERIOR. WHILE IT DOESN`T HAPPEN
TOO OFTEN...CONFIDENCE IN THE LATTER PORTION OF THE LONG TERM IS
MUCH MUCH HIGHER THAN THE EARLY PART. DURING THE EARLY PART...THERE
REMAINS CONSIDERABLE UNCERTAINTY IN THE EVOLUTION OF THE WRN TROF
THRU THE CNTRL INTO ERN CONUS. THAT UNCERTAINTY CENTERS AROUND
WHETHER THE PIECE OF ENERGY IN THE SRN PART OF THE WRN TROF LIFTS
OUT AND PHASES WITH ENERGY DROPPING SE OUT OF CANADA. MORE ON THAT
LATER.

BEGINNING SUN NIGHT...ATTENTION WILL BE ON THE SHORTWAVE THAT IS
CURRENTLY LIFTING NE ACROSS AZ IN RESPONSE TO TROF THAT IS NOW
AMPLIFYING ALONG THE W COAST. WAVE LOOKS VERY WELL-DEFINED ON WATER
VAPOR IMAGERY WITH AN ASSOCIATED PLUME OF PACIFIC MOISTURE. AS
SHORTWAVE CONTINUES TO LIFT NE...MODELS SHOW A NICE SHALLOW STREAM
OF MOISTURE GETTING TAPPED OFF THE GULF. SO...WITH THE SHALLOW
MOISTURE FEED...WAA/ISENTROPIC ASCENT AHEAD OF WAVE WILL LEAD TO AN
AREA OF PCPN DEVELOPING ACROSS THE CNTRL PLAINS AND THEN EXPANDING
AS IT SHIFTS INTO THE GREAT LAKES. PRECIPITABLE WATER ALSO INCREASES
TO 200-300PCT OF NORMAL. SO IF FORCING IS STRONG...MAY SEE SOME
DECENT PCPN AMOUNTS. OVERALL...MODELS ARE TRENDING SLIGHTLY MORE
DEFINED WITH SHORTWAVE WHICH LOOKS ON TRACK GIVEN CURRENT WATER
VAPOR IMAGERY AND DESPITE THE FACT THAT IT WILL BE WEAKENING AS IT
LIFTS NE THRU THE BUILDING LARGER SCALE RIDGE. MODELS ARE ALSO
TRENDING A LITTLE FARTHER N AND W WITH ASSOCIATED PCPN. NAM/REGIONAL
GEM REPRESENT THE THE NW SIDE OF THE 12Z MODEL RUNS WITH BOTH
SPREADING PCPN SQUARELY ACROSS UPPER MI. NAM HAS AMOUNTS FROM
0.25-0.6 INCHES WHILE THE GEM HAS 0.15-0.3 INCHES. ALTHOUGH A LITTLE
SKEPTICAL OF THESE MORE NW SOLUTIONS...TRENDS FROM REMAINING
GUIDANCE STILL SUPPORT CONTINUING TREND FROM PREVIOUS FCST TO BUMP
UP POPS FOR SUN NIGHT. PER 295K SFC...A HEALTHY PUSH OF ISENTROPIC
ASCENT IS INDICATED TO SPREAD INTO THE GREAT LAKES REGION WHICH SHOULD
LEAD TO A DECENT AREA OF PCPN. PTYPE MAY BE AN ISSUE AS 850MB TEMPS
RISE TO AROUND 0C SUN. HOWEVER...WITH WETBULB PROFILE BLO 0C...SEEMS
LIKELY THAT TEMP PROFILE WILL QUICKLY FALL SUBZERO DUE TO
EVAPORATIVE COOLING AS WELL AS DYNAMIC COOLING. PLAN FOR NOW WILL BE
TO UTILIZE JUST SNOW AS PTYPE SUN NIGHT. 295K SFC SHOWS MIXING
RATIOS AROUND 4G/KG...SUGGESTING POTENTIAL FOR UP TO 8 INCHES OF
SNOW WHERE MAX ASCENT OCCURS. SINCE DURATION OF PCPN WILL PROBABLY
BE ON THE ORDER 9HRS...HIGH END SNOW TOTALS COULD REACH 6 INCHES IF
MAX FORCING DOES SPREAD INTO UPPER MI. WILL CONTINUE TO PAINT THE
HIGHER PCPN AMOUNTS OVER THE SE FCST AREA WHERE SNOW AMOUNTS OF 2 TO
4 INCHES WILL BE INCLUDED FOR THIS FCST. MAY SEE 1-2 INCHES NW. ON
THE BACKSIDE OF SNOW AREA...PCPN MAY TRANSITION TO SOME -FZDZ SW TO
NE MON MORNING AS MID LEVEL MOISTURE PULLS OUT. THERE SHOULD THEN BE
A TREND TO DRY WEATHER DURING THE DAY MON.

OVER THE LAST FEW DAYS...THE BIGGEST UNCERTAINTY HAS BEEN THE
TUE/WED TIME PERIOD DUE TO THE CONSIDERABLE SPREAD OF SOLUTIONS
REGARDING THE EASTWARD PROGRESSION/EVOLUTION OF THE CURRENTLY
AMPLIFYING WRN CONUS TROF. MAIN POINTS OF UNCERTAINTY INVOLVE
WHETHER THE ENERGY IN THE BASE OF THE WRN TROF DROPS OUT AND HANGS
BACK OVER THE SW...OR IF IT DOES NOT...WILL IT LIFT NE AND PHASE
WITH ENERGY DROPPING SE TOWARD THE GREAT LAKES. THE ECMWF HAD
SEVERAL RUNS FAVORING THE IDEA OF DROPPING THE ENERGY OUT. IT IS NOW
TRENDING BACK TO KEEPING THE SRN PORTION PROGRESSIVE...BUT IT DOES
NOT LIFT ENERGY NE TO PHASE WITH THE NRN PORTION IN THE GREAT LAKES
REGION. THE GFS HAS HAD THE MOST RUNS FAVORING PHASING OF ENERGY IN
THE VCNTY OF THE GREAT LAKES WITH THE GLOBAL GEM/UKMET ALSO
GENERALLY LEANING IN THAT DIRECTION ON MOST RUNS. AGAIN...AS IN
PREVIOUS DAYS...THERE ARE A FEW GFS ENSEMBLES THAT HAVE A DEEP STORM
MOVING NE THRU THE UPPER LAKES REGION. AT THIS POINT...GIVEN THE
SPREAD OF SOLUTIONS...PARTICULARLY WITH REGARD TO THE ALWAYS
UNCERTAIN PHASING OF STREAMS AND LOCATIONS OF SUCH OCCURRENCE...
THERE IS NOT ENOUGH CONFIDENCE TO REALLY TREND INHERITED FCST MUCH
IN ANY DIRECTION. SO...AS HAS BEEN THE CASE IN RECENT DAYS...BEST
PATH WILL CONTINUE TO BE TO USE A CONSENSUS OF RECENT MODEL RUNS
UNTIL THE DETAILS ARE SORTED OUT. GIVEN THE WARMTH PUSHING INTO THE
AREA OVER THE NEXT FEW DAYS...MIXED PCPN COULD BE AN ISSUE...AND FOR
THIS FCST ISSUANCE WILL KEEP A MENTION OF A MIX...RANGING FROM
MOSTLY RAIN FOR A TIME SE TO MAINLY SNOW NW. DEPENDING ON TRACK OF
SFC LOW AND WHETHER IT DEEPENS SUBSTANTIALLY...THERE COULD BE A
TRANSITION TO SIGNIFICANT SNOW/BLSN LATER TUE INTO WED NEAR LAKE
SUPERIOR WHERE LAKE ENHANCEMENT/LES WILL GET UNDERWAY. LAKE SUPERIOR
LES WILL THEN BE THE RULE WED THRU FRI AS ARCTIC AIR SETTLES OVER
THE AREA (850MB TEMPS FALL TO -20 TO -25C). UTILIZED CATEGORICAL
POPS FOR THE USUAL AREAS FAVORED BY NW WINDS WED THRU FRI GIVEN VERY
HIGH CONFIDENCE IN LES. CLIPPER TYPE SYSTEM ARRIVING SAT MAY RESULT
IN -SN SPREADING INTO AREAS AWAY FROM LES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1232 PM EST SAT JAN 26 2013

LAKE EFFECT SNOW IS DIMINISHING ACROSS THE AREA EARLY THIS
AFTERNOON AS HIGH PRESSURE MOVES OVERHEAD AND LEADS TO VARIABLE
WINDS. THUS...EXPECT CONDITIONS IMPROVING TOWARDS VFR AT ALL SITES
THROUGH THE AFTERNOON HOURS. AFTER THAT...EXPECT VFR CONDITIONS AT
THE TAF SITES THROUGH THE REST OF THE PERIOD AS MID LEVEL CLOUDS
MOVE ACROSS UPPER MICHIGAN TONIGHT. THERE COULD BE A BRIEF PERIOD
OF -SHSN OR FLURRIES AT KCMX/KSAW...BUT IT SHOULDN/T AFFECT
VISIBILITIES. THESE CLOUDS SHOULD PUSH EAST ON SUNDAY MORNING AND
JUST LEAVE SOME PASSING MID CLOUDS. DID PUT A MENTION OF SCATTERED
LOW CLOUDS AT KSAW TOMORROW MORNING...SINCE THE MODELS ARE HINTING
AT THAT POSSIBILITY.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 421 PM EST SAT JAN 26 2013

HIGH PRESSURE CURRENTLY OVERHEAD WILL SHIFT EAST TONIGHT AND LEAD
TO INCREASING SOUTHERLY WINDS...BUT EXPECT GUSTS TO REMAIN BELOW
25KTS. WINDS WILL REMAIN BELOW 25KTS THROUGH THE FIRST COUPLE OF
DAYS OF THE UPCOMING WORK WEEK DUE TO WEAK PRESSURE GRADIENTS. A
LOW MOVING THROUGH THE GREAT LAKES ON TUESDAY AND THEN INCREASING
IN INTENSITY OVER EASTERN CANADA WILL PRODUCE INCREASING NORTHERLY
WINDS TO 30KTS TUESDAY NIGHT INTO WEDNESDAY. THIS...COMBINED WITH
COLDER AIR SURGING SOUTH...WILL LEAD TO FREEZING SPRAY FOR THE
MIDDLE AND END OF THE WORK WEEK.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...

UPPER MICHIGAN...NONE.
LAKE SUPERIOR...NONE.
LAKE MICHIGAN...NONE.

&&

$$

SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...SRF
MARINE...SRF




AREA FORECAST DISCUSSION

NWS MARQUETTE MI

 312 PM EST SAT JAN 26 2013

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 311 PM EST SAT JAN 26 2013

LAKE EFFECT HAS BEEN GRADUALLY DIMINISHING THROUGH THE AFTERNOON
HOURS...AS THE NORTHERLY FLOW HAS SLOWED WITH HIGH PRESSURE MOVING
OVER THE CWA. STILL HAVE SOME LIGHT SNOW SHOWERS OVER THE NORTH
CENTRAL CWA...BUT EXPECT THEM TO END OR PUSH NORTH DURING THE LATE
AFTERNOON AND EARLY EVENING. OTHERWISE...A FAIRLY NICE AFTERNOON
WITH LIGHT WINDS AND TEMPERATURES AT OR SLIGHTLY BELOW NORMAL AS OF
3PM.

HIGH PRESSURE CENTERED OVER THE UPPER GREAT LAKES WILL SHIFT EAST
TONIGHT AS THE UPPER RIDGE BUILDS NORTHEAST INTO THE UPPER
MISSISSIPPI VALLEY. AS THIS OCCURS...BROAD H800-600 WARM AIR
ADVECTION CURRENTLY IN MINNESOTA AND STARTING TO MOVE INTO WESTERN
LAKE SUPERIOR WILL CONTINUE EAST ACROSS THE CWA TONIGHT. SO FAR
TODAY...HAVE ONLY SEEN A FEW OBS REPORTING SNOW SHOWERS FROM THIS
MID CLOUD DECK IN NORTHERN MN...WHICH WAS LIKELY HELD OFF BY DRY
H925-850 AIR SEEN ON 12Z KINL SOUNDING AND RUC SOUNDINGS IN THAT
AREA. LATEST MODELS DO TRY TO MOISTEN THE CENTRAL CWA TOWARDS
MIDNIGHT...AS THE STRONGER H925-850 WAA SLIDES EAST ALONG THE WI
BORDER. NOT LIKING HOW QUICKLY THINGS MOISTEN...BUT WITH THE IDEA IN
SEVERAL MODELS...WILL ADD SLIGHT CHANCES THERE. WILL KEEP THE BEST
POPS OVER THE NORTHERN HALF OF LAKE SUPERIOR WHERE THE LOWER LEVELS
WERE A LITTLE MORE MOIST AND THE MID LEVEL WAA WAS THE STRONGEST.
ALSO ADDED A MENTION OF FLURRIES TO AREAS SURROUNDING THE POPS TO
ACCOUNT FOR SOME SNOW MAKING IT THROUGH THE DRY AIR.

THE OTHER ITEM OF CONCERN HEADING INTO THE OVERNIGHT HOURS WILL BE
THE INCREASED MOISTENING OF THE LOWER LEVELS OFF LAKE MICHIGAN. AS
THIS OCCURS...THE H850 TEMPS WILL BE WARMING TOWARDS -10C
OVERNIGHT...SO DON/T EXPECT LAKE ENHANCEMENT TO GET TOO OUT OF
HAND. BUT WITH THE SNOW ALOFT FEEDING INTO THE LOWER LEVELS FORCING
THAT IS MAINLY BELOW -10C...EXPECT SNOW TO DEVELOP THERE. H925 WINDS
ARE FAVORABLE FOR SOUTHERN LUCE AND SOUTHEAST SCHOOLCRAFT...SO HAVE
INCREASED POPS INTO LOW END LIKELY VALUES FOR THOSE LOCATIONS
AND TAPERED IT OFF FAIRLY QUICKLY TO THE WEST. WITH SNOW RATIOS ON
THE LOW END...AROUND 10-14 TO 1 INITIALLY AND TRENDING
TOWARDS 8-1 SUNDAY MORNING...EXPECT ACCUMULATIONS TO BE FAIRLY LIGHT
IN THOSE AREAS WITH ONLY AN INCH OF ACCUMULATION. THE LAKE EFFECT
SHOULD DIMINISH LATER SUNDAY MORNING INTO THE EARLY AFTERNOON DUE TO
THE CONTINUED WARMING OF TEMPS ALOFT SHOVING INVERSION HEIGHTS TO
3KFT.

SUNDAY LOOKS TO BE FAIRLY QUIET...AS THE AREA IS BETWEEN THE
EXITING WARM AIR ADVECTION PRECIPITATION AND THE NEXT APPROACHING
SYSTEM FOR SUNDAY NIGHT. THE NEXT WAVE IS CURRENTLY OVER
SOUTHERN CALIFORNIA AND QUICKLY MOVES NORTHEAST AND
TOWARDS THE AREA TONIGHT AND SUNDAY. WITH THE INCREASED CONSISTENCY
IN THE MODELS...HAVE DELAYED THE START OF THE PRECIPITATION UNTIL
00Z AND LATER. THE LONG TERM DISCUSSION WILL COVER THIS SYSTEM IN
FURTHER DETAILS.

OTHERWISE...WILL SEE A GAP IN THE CLOUDS BEHIND THE WAA
CLOUDS DEPARTING IN THE MORNING AND THE INCREASING CLOUDS FROM THE
SOUTHWEST IN THE AFTERNOON. THINK THIS CLEARING WILL BE MOST LIKELY
OVER THE WEST HALF AND HAVE TRENDED TOWARDS PARTLY-MOSTLY SUNNY SKY
FOR PERIOD AROUND MID DAY. FARTHER EAST...NAM/GFS ARE HINTING AT
SOME LOWER CLOUDS DEVELOPING TONIGHT AND REMAINING THROUGH MUCH OF
SUNDAY. NOT OVERLY CONFIDENT ON THIS SOLUTION WITH THE DRY AIR
UPSTREAM...BUT WITH THE EXITING MID CLOUDS AND APPROACHING HIGH
CLOUDS...A PARTLY-MOSTLY CLOUDY FORECAST SEEMED WARRANTED.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 521 AM EST SAT JAN 26 2013

INCREASED POPS/QPF S CENTRAL AND NEAR LAKE MI SUNDAY AFTERNOON AND
EVENING WITH MUCH OF THE SYSTEM SNOW PASSING JUST TO OUR SOUTH.
WHILE THE MAJORITY OF SOLUTIONS KEEP IT AS A GLANCING BLOW TO THE
REGION...THE 26/00Z ECMWF SOLUTION BRINGS 0.1 TO 0.16 ACROSS A
MAJORITY OF THE CWA. THE 26/06Z NAM HAS ALSO GONE WITH THIS MORE NW
PUSH OF MOISTURE...GIVING EXTRA CONFIDENCE IN THE LIKELY POPS THAT
WHERE THROWN IN ALONG THE LAKE MI SHORELINE SUNDAY NIGHT. UNDER A
RELATIVELY WARM AIRMASS...WITH 850MB TEMPS AROUND 04C...MIXED PRECIP
MAY BECOME A CONCERN EARLIER THAN ORIGINALLY ANTICIPATED. WILL NOT
GET TOO FANCY WITH PRECIP TYPE QUITE YET...GIVEN THE OVERALL
UNCERTAINLY IN PRECIP AMOUNTS. WILL STILL KEEP THE MENTION MIXED
PRECIP...AND MORE SPECIFICALLY FREEZING RAIN...FOR MONDAY NIGHT AND
TUESDAY.

DRY WEATHER SHOULD QUICKLY TAKE HOLD WEST TO EAST ON MONDAY...BEFORE
THE NEXT SYSTEM APPROACHES LATE MONDAY INTO MONDAY NIGHT. WITH TEMPS
REMAINING WARM AND AT OR ABOVE FREEZING FOR HIGHS MONDAY...850MB
TEMPS OF -1 TO 5C AT 06Z TUESDAY...AND COLDER AIR WORKING IN FROM
THE NW TUESDAY AFTERNOON MUCH OF THE PRECIP SHOULD QUICKLY CHANGE
OVER TO OR JUST REMAIN IN THE FORM OF SNOW. OVER THE S CENTRAL AND
FAR E PORTIONS OF THE CWA...MUCH OF THE MIXED PRECIP SHOULD STAY
OVER THE CENTRAL AND E.

A SFC LOW OFF THE ROCKIES EARLY IN THE WEEK WILL BRIEFLY SETTLE
ACROSS KS MONDAY NIGHT...BEFORE EJECTING NE ACROSS THE UPPER GREAT
LAKES TUESDAY MORNING THROUGH WEDNESDAY. THE 25/06Z ECMWF ENDS UP
BEING APPROX 12-18HRS WITH THE TRACK OF THE SFC LOW...EJECTING INTO
E ONTARIO AND QUEBEC WEDNESDAY. AS A RESULT OF COOLER AIR WRAPPING
IN BEHIND THE EXITING LOW...EXPECT ANOTHER COOL DOWN FOR THE MIDDLE
AND END OF THE WORK WEEK...BACK TO CLIMO FOR HIGHS ON
WEDNESDAY...AND THEN IN THE SINGLE DIGITS AGAIN OVER THE W HALF ON
THURSDAY. THIS COLDER AIR...AND NW WINDS OF 10-20KTS OVER THE WARM
WATERS OF LAKE SUPERIOR SHOULD BRING AN EXTENDED OF LES ACROSS THE
FAVORABLE NW-NNW FLOW AREAS. KEPT WITH THE HIGHER POPS ACROSS THE
FAR W AND KEWEENAW PENINUSLA FROM TUESDAY NIGH THROUGH THE REMAINDER
OF THE FCST PERIOD /FRIDAY/.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1232 PM EST SAT JAN 26 2013

LAKE EFFECT SNOW IS DIMINISHING ACROSS THE AREA EARLY THIS
AFTERNOON AS HIGH PRESSURE MOVES OVERHEAD AND LEADS TO VARIABLE
WINDS. THUS...EXPECT CONDITIONS IMPROVING TOWARDS VFR AT ALL SITES
THROUGH THE AFTERNOON HOURS. AFTER THAT...EXPECT VFR CONDITIONS AT
THE TAF SITES THROUGH THE REST OF THE PERIOD AS MID LEVEL CLOUDS
MOVE ACROSS UPPER MICHIGAN TONIGHT. THERE COULD BE A BRIEF PERIOD
OF -SHSN OR FLURRIES AT KCMX/KSAW...BUT IT SHOULDN/T AFFECT
VISIBILITIES. THESE CLOUDS SHOULD PUSH EAST ON SUNDAY MORNING AND
JUST LEAVE SOME PASSING MID CLOUDS. DID PUT A MENTION OF SCATTERED
LOW CLOUDS AT KSAW TOMORROW MORNING...SINCE THE MODELS ARE HINTING
AT THAT POSSIBILITY.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 311 PM EST SAT JAN 26 2013

HIGH PRESSURE CURRENTLY OVERHEAD WILL SHIFT EAST TONIGHT AND LEAD
TO INCREASING SOUTHERLY WINDS...BUT EXPECT GUSTS TO REMAIN BELOW
25KTS. WINDS WILL REMAIN BELOW 25KTS THROUGH THE FIRST COUPLE OF
DAYS OF THE UPCOMING WORK WEEK DUE TO WEAK PRESSURE GRADIENTS. A
LOW MOVING THROUGH THE GREAT LAKES ON TUESDAY AND THEN INCREASING
IN INTENSITY OVER EASTERN CANADA WILL PRODUCE INCREASING NORTHERLY
WINDS TO 30KTS TUESDAY NIGHT INTO WEDNESDAY. THIS...COMBINED WITH
COLDER AIR SURGING SOUTH...WILL LEAD TO FREEZING SPRAY FOR THE
MIDDLE AND END OF THE WORK WEEK.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...SRF
LONG TERM...KF
AVIATION...SRF
MARINE...SRF






AREA FORECAST DISCUSSION

NWS OMAHA/VALLEY NE

 331 PM CST SAT JAN 26 2013

.SHORT TERM...TONIGHT THROUGH TUESDAY
SHORT TERM FORECAST CONCERNS WILL BE THE ASSOCIATED DETAILS WITH
THE PRECIPITATION EVENT TONIGHT AND SUNDAY...THEN DRIZZLE AND FOG
AS LIFT DECREASES LATER SUNDAY INTO SUNDAY NIGHT. POTENTIAL FOR
LIGHT PRECIPITATION MONDAY IN SOUTHEAST NEB NEAR H85 FRONT AND IN
THE NORTHEAST NEB WITH A COLD FRONT AND ACROSS THE FORECAST AREA
INTO TUESDAY.

THE SURFACE WARM FRONT IS LIFTING NORTH AND BRISK SOUTH WINDS HAVE
WARMED TEMPERATURES INTO THE 40S AND 50S...WITH BEATRICE NEARLY
REACHING 60. SURFACE DEWPOINTS ARE VARIABLE IN THE TEENS AND 20S.
3HR PRESSURE FALLS WERE NOTED ACROSS MUCH OF THE PLAINS IN
RESPONSE TO LOWERING PRESSURE OVER THE EASTERN ROCKIES.

PER VISIBLE SATELLITE AND METARS...LOW LEVEL STRATUS IS BEGINNING
TO WORK NORTH AND THIS IS THE LEADING EDGE OF THE MID 30S
DEWPOINTS. WATER VAPOR SATELLITE IMAGERY AND LIGHTNING
DATA...SHOWED THE SHORTWAVE TROF HAD MOVED INTO THE SOUTHWEST
U.S. BY MIDDAY AND THERE WERE LIGHTNING STRIKES OVER EASTERN
ARIZONA. THIS WAVE WILL BE OUR WEATHER MAKER THROUGH SUNDAY.

THE H9 JET IS FROM THE SOUTH AT 25 TO 35KT AND WILL CONTINUE TO
INCREASE TO 35 TO 45KT OVER THE FORECAST AREA THROUGH 06Z.
MEANWHILE...THE NOSE OF THE H85 50KT JET IS OVER SOUTHWEST KS.
THETA-ADVECTION AND H7 OMEGA INCREASE ACROSS KANSAS THROUGH 06Z
AND THEN ACROSS NEBRASKA INTO IOWA AND MISSOURI THROUGH 12Z. THERE
ALSO IS SOME UPPER LEVEL JET SUPPORT BY 12Z.

THE 4KM WRF/NAM/GFS/SREF/EC/RAP ARE SIMILAR IN HAVING THE
PRECIPITATION OVERSPREADING THE FORECAST AREA FROM SOUTHWEST TO
NORTHEAST MAINLY BETWEEN 08Z AND 14Z. REGARDING PRECIPITATION
TYPE...WILL NEED TO MONITOR AREAS IN FAR NORTHEAST NEBRASKA AND
PARTS OF WESTERN IOWA SHOULD PRECIPITATION BEGIN AS FREEZING RAIN.
THE MODELS ARE NOT IN GOOD AGREEMENT WITH THE LOW LEVEL TEMPS. THE
NAM SEEMS QUITE COOL...AND SEVERAL OF THE OTHER MODELS ARE A BIT
WARMER. TRENDED WITH THE WARMER RAP TEMPERATURES VERSUS THE
COOLER NAM TEMPS. WITH THE VERY MILD CONDITIONS THIS EVENING AND
INCREASING CLOUDS AND STRONG SOUTH FLOW...THINK MOST LOCATIONS
WILL BE ABOVE FREEZING WHEN THE PRECIPITATION STARTS...SO LEFT
FREEZING MENTION ONLY IN THE FAR NORTHEAST ZONES. AS THE SHORTWAVE
MOVES EAST...SO DOES THE PRECIPITATION AND LOOK FOR DRIZZLE AND
FOG LATER SUNDAY AFTERNOON AND SUNDAY NIGHT. RAINFALL AMOUNTS
LOOK TO VARY FROM 0.1 TO .4 OF AN INCH.

THE COLD FRONT IS NEAR FALLS CITY BY 06Z SUNDAY NIGHT...HOWEVER
THE LOW LEVEL MOISTURE DOES NOT GET SCOURED OUT. WITH THE WEAK
FLOW OVERNIGHT DO MENTION FOG. WILL NEED TO WATCH FOR BELOW
FREEZING TEMPERATURES AND FOG FOR THE MONDAY MORNING COMMUTE...AS
THIS COULD CAUSE PROBLEMS.

MONDAY...THERE IS WARM AIR ADVECTION ACROSS THE SOUTHERN CWA
AND MAY SEE SOME LIGHT PRECIP. IN THE NORTHWEST PART OF THE
FORECAST AREA...THERE IS A REINFORCING COLD FRONT SLOWLY MOVING
SOUTHEAST ASSOCIATED WITH THE MID LEVEL TROF. THIS FRONT HAS SOME
DECENT FRONTOGENESIS WITH IT AND MONDAY INTO TUESDAY COULD BRING
SOME RAIN...A MIX AND THEN POSSIBLE A NARROW BAND OF LIGHT SNOW.
IT IS INTERESTING THAT THERE IS SOME ELEVATED INSTABILITY WITH
THIS BAND AND ALSO NEAR THE H85 FRONT IN SOUTHERN NEBRASKA MONDAY
NIGHT. FOR NOW...TOP/EAX HAVE SOME TSRA MENTIONED IN THEIR CWA
MONDAY NIGHT AND WE HAVE RAIN IN THE SOUTH AND A RAIN/SNOW MIX
THEN ALL SNOW NORTH.

TEMPERATURES ARE GOING TO BE A CHALLENGE EACH DAY AND HAVE HIGHS
SUNDAY AND MONDAY IN THE 30S TO AROUND 40 FAR NORTH TO THE 50S
SOUTH. TUESDAY HAVE HIGHS IN THE LOWER 30S NORTH TO UPPER 40S
SOUTH.

ZAPOTOCNY

.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY.

THE UPPER LEVEL FLOW PATTERN WILL TRANSITION TO THE NORTHWEST
DURING THIS PERIOD AND THE GLOBAL MODELS ARE IN PRETTY GOOD
AGREEMENT ON THIS EVOLUTION. THE UPPER LEVEL TROUGH FOR MON/TUE WILL
JUST BE EXITING THE REGION ON TUE NIGHT AND WILL LINGER SOME SCHC
POPS FOR -SN IN THE SOUTH AS THIS EXITS...OTHERWISE THE EXTENDED
PART OF THE FORECAST IS DRY. AN ARCTIC COLD FRONT WILL MOVE THROUGH
THE FA ON WED NIGHT WHICH WILL LEAD TO MUCH COLDER HIGHS ON THU AND
LOWS THU NIGHT. BUT LIKE RECENT COLD SURGES...THIS WILL BE GREATLY
MODIFIED BY THE LACK OF SNOW COVER ACROSS THE FA. THUS WE ARE
EXPECTING HIGHS IN THE TEENS/20S AND LOWS IN THE SINGLE DIGITS ABOVE
ZERO. THE UPPER LEVEL RIDGE TO THE WEST WILL SHIFT A BIT EAST ON ON
FRI/SAT AND ALLOW FOR SOME DOWN-SLOPE AND PACIFIC AIR TO SPILL BACK
INTO THE FA. NORMAL HIGHS WITH NO SNOW COVER BY THE END OF THE
PERIOD ARE IN THE LOWER TO MID 40S...AND WE SEE NO REASON WE CAN`T
GET NEAR THESE NUMBERS. THUS WE HAVE GONE ABOVE THE CLIMO HEAVY MOS
GUIDANCE FOR THE END OF THE PERIOD.

BOUSTEAD

&&

.AVIATION...
18Z TAFS FOR KOFK...KOMA AND KLNK.

VFR CONDITIONS ARE FORECAST TO CONTINUE UNTIL AFTER 09Z WHEN
CEILING AND VISIBILITY CONDITIONS DETERIORATE TO MVF AND IFR
CONDITIONS AS SURFACE WARM FRONT LIFTS NORTHEASTWARD ACROSS
IOWA AND EASTERN NEBRASKA. LIGHT RAIN WILL BEGIN AFTER 10Z AT KOMA
AND KLNK AND AFTER 12Z AT KOFK. STRONG SOUTHERLY LOW LEVEL FLOW
WILL CREATE LOW LEVEL WIND SHEAR AFTER 00Z AT KOFK AND AFTER
02-03Z AT KLNK AND KOMA.

SMITH

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

$$



AREA FORECAST DISCUSSION

NWS LA CROSSE WI

 1114 AM CST SAT JAN 26 2013

.SHORT TERM...TODAY THROUGH MONDAY NIGHT
413 AM CST SAT JAN 26 2013

MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES...TYPES AND
AMOUNTS FOR SUNDAY AND SUNDAY NIGHT.

CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED TROUGHING OFF THE PACIFIC NORTHWEST COAST...AN UPPER LOW NEAR
SAN DIEGO CA...RIDGING PROGRESSING INTO THE NORTHERN PLAINS...AND
TROUGHING FROM SOUTHEAST CANADA INTO NEW ENGLAND. THE FORECAST AREA
LIES IN THE SUBSIDENT PORTION AHEAD OF THE UPPER RIDGING...RESULTING
IN DRYING AND HIGH PRESSURE AT THE SURFACE. 00Z MPX SOUNDING SHOWED
A LOT OF DRY AIR ABOVE 800MB...WITH A PRECIPITABLE WATER OF 0.17
INCHES OVERALL. SATELLITE IMAGERY DEPICTS MAINLY CLEAR SKIES OVER
THE FORECAST AREA. AIRMASS ASSOCIATED WITH THE HIGH PRESSURE AREA
WAS ALSO RELATIVELY CHILLY WITH A 925MB TEMP OF -17C AT MPX.
COMBINATION OF THE CLEAR SKIES...DIMINISHING WINDS AND THE CHILLY
AIR HAS ALLOWED TEMPERATURES TO DROP INTO THE SINGLE DIGITS ABOVE
ZERO. TO THE NORTHWEST...MID AND HIGH CLOUDS WERE STREAMING ACROSS
NORTH DAKOTA AND NORTHWEST MN...ASSOCIATED WITH PACIFIC MOISTURE ON
WATER VAPOR BECOMING ENHANCED BY UPPER JET FORCING...AS WELL AS WARM
ADVECTION. WELL TO THE SOUTH...AN AREA OF PRECIPITABLE WATER VALUES
OF 0.8 INCHES AND HIGHER WAS PRESENT ACROSS MUCH OF TEXAS AND
LOUIS ANA...WELL DOWNSTREAM OF THE SAN DIEGO UPPER LOW.

TODAY AND TONIGHT...MODELS SHOW THE TROUGHING JUST OFF THE PACIFIC
NORTHWEST DIGGING INTO NORTHERN CALIFORNIA. ALTHOUGH THIS IS QUITE
FAR AWAY FROM HERE...THERE ARE NUMEROUS IMPACTS FROM IT. THE FIRST
IS TO KEEP PUSHING THE RIDGING COMING INTO THE NORTHERN PLAINS
EASTWARD...WITH ITS RIDGE AXIS PROGGED TO BE CENTERED OVER THE
FORECAST AREA AT 12Z SUNDAY. WARMER AIR WILL ACCOMPANY THE RIDGE...
WITH 925MB TEMPS CLIMBING TO -6 TO -10C BY 00Z AND -2 TO -5C BY 12Z
SUNDAY. THE SECOND IMPACT IS TO EJECT AND POSSIBLY SHEAR OUT THE SAN
DIEGO CA UPPER LOW...LIFTING IT UP TO AROUND GOODLAND KS BY 12Z
SUNDAY. AS THIS UPPER LOW APPROACHES THE CENTRAL PLAINS TONIGHT...A
LOW LEVEL JET DEVELOPS...PULLING THE MOISTURE SEEN ACROSS TEXAS
NORTHWARD. AT 12Z SUNDAY...PRECIPITABLE WATER VALUES BETWEEN 0.8-1
INCHES ARE POSSIBLE AS FAR NORTH AS DES MOINES IA AND OMAHA
NE...WHICH ARE ALMOST 300 PERCENT ABOVE NORMAL. WITH SO MUCH
MOISTURE RUNNING INTO A DRY AND COLDER AIRMASS PRESENT HERE ACROSS
THE UPPER MIDWEST...LOW CLOUDS AND PRECIPITATION SHOULD EASILY
DEVELOP. 26.00Z NAM/GFS/ECMWF/CANADIAN/UKMET ARE ALL IN GOOD
AGREEMENT KEEPING ANY PRECIPITATION SOUTH OF THE AREA PRIOR TO 12Z.
NOTE...THOUGH...THAT BY 12Z...PRECIPITATION SHOULD BE PRESENT FROM
KANSAS CITY TO OMAHA AND DES MOINES. FULL SUN THIS MORNING FOLLOWED
BY FILTERED SUN THROUGH MID/HIGH CLOUDS IN THE AFTERNOON...COMBINED
WITH THE WARMER AIR MOVING IN AND LIMITED SNOW ON THE GROUND...
SHOULD ALLOW TEMPERATURES TO CLIMB INTO THE LOW TO MID 20S. CLOUDS
FURTHER INCREASE TONIGHT...AND WITH WINDS PICKING UP ADVECTING
WARMER/MOIST AIR IN...THINK TEMPERATURES WILL FALL JUST A LITTLE IN
THE EVENING THEN MOSTLY HOLD STEADY OR RISE. FINAL NOTE ABOUT THE
CLOUD INCREASE TONIGHT...BOTH THE GFS AND REGIONAL CANADIAN PRODUCE
A LITTLE LIGHT SNOW ACROSS TAYLOR/CLARK COUNTIES FROM THE MID CLOUDS
THIS EVENING. ADDED SOME FLURRIES FOR NOW...GIVEN DRY WEATHER
SIGNALED BY OTHER MODELS.

SUNDAY AND SUNDAY NIGHT...THE TROUGHING DIGGING INTO NORTHERN
CALIFORNIA IS FORECAST TO DIG EVEN MORE DURING THIS PERIOD...AIDED
TOO BY A POTENT SHORTWAVE DROPPING THROUGH THE PACIFIC NORTHWEST.
THE RESULT BY 12Z MONDAY IS A FULL-FLEDGED TROUGH OVER THE WESTERN
1/3 OF THE U.S. IN RESPONSE...500MB HEIGHTS RISE DOWNSTREAM ACROSS
THE REST OF THE U.S.. THIS WILL CAUSE THE SHEARING OUT UPPER LOW
NEAR GOODLAND KS AT 12Z TO LIFT UP INTO THE FORECAST AREA BY 00Z
MONDAY. MODELS STILL DIFFER A BIT ON STRENGTH...BUT THE GENERAL
CONSENSUS IS THAT THE PRECIPITATION THAT DEVELOPS TONIGHT AROUND THE
KC...OMAHA AND DES MOINES AREAS WILL END UP TRANSLATING NORTHEAST
WITH THE SHEARING OUT UPPER LOW...IMPACTING THE FORECAST AREA. GOOD
SETUP FOR PRECIPITATION AS THE SURGE OF HIGH PRECIPITABLE WATER (FOR
THIS TIME OF YEAR) COMBINES WITH ISENTROPIC LIFT AND DPVA FROM THE
SHORTWAVE. REALLY GOOD AGREEMENT EXISTS NOW THAT MUCH OF THE AREA
BETWEEN 18Z SUNDAY AND 06Z MONDAY WILL SEE PRECIPITATION. IN
FACT...EVEN THE EXPECTED AMOUNTS BETWEEN THE 26.00Z
GFS/UKMET/ECMWF/CANADIAN...26.06Z NAM AND 26.03Z SREF ARE ALL REALLY
CLOSE...IN THE 0.25-0.6 RANGE...AND AGAIN MUCH OF THIS FALLING
DURING THAT 18Z SUN - 06Z MON. THE HIGHEST MAXIMUM HAS SHIFTED
NORTH...AFFECTING THE SOUTHEAST HALF OF THE FORECAST AREA INTO
NORTHERN ILLINOIS. GIVEN THE GREAT MODEL AGREEMENT...HAVE RAISED
PRECIPITATION CHANCES EVEN MORE. IT IS INTERESTING SCENARIO WITH
REGARDS TO PRECIPITATION TYPE. INITIALLY THERE IS SOME DRY AIR TO
OVERCOME WHILE WARM ADVECTION IS TAKING PLACE. THIS FAVORS MORE OF
FREEZING RAIN/SLEET AT THE ONSET...TRANSITIONING TO SLEET/SNOW
QUICKLY AS DYNAMIC COOLING TAKES OVER. YOU CAN SEE THIS NICELY IN
850MB TEMPS FROM THE MODELS. AS TIME PROGRESSES THROUGH THE
AFTERNOON AND EVENING...EVENTUALLY THE WARM AIR STARTS SPREADING
NORTH THROUGH THE AREA...CAUSING THE SNOW OR SLEET TO TRANSITION TO
FREEZING RAIN...ESPECIALLY SOUTH OF I-90. THEN...TO MAKE MATTERS
WORSE...THE ICE BEGINS TO LEAVE THE CLOUDS...LEAVING WHAT WILL
PROBABLY BE A FREEZING DRIZZLE AFTER MIDNIGHT. IN SUMMARY...A MESS.
COULD REALLY SEE A DECENT AMOUNT OF SLEET IN THIS EVENT...ESPECIALLY
ALONG/SOUTH OF I-90...SINCE THE BALANCE OF COOLING FROM
PRECIPITATION AND THE WARM ADVECTION KEEPS THE MAX TEMPERATURE ALOFT
IN THE 1-3C RANGE. GIVEN THAT WE COULD HAVE VARIOUS PRECIPITATION
TYPES EXCEEDING WARNING CRITERIA...AS WELL AS THE MODEL TRENDS NORTH
WITH THE MAX QPF...HAVE ISSUED A WINTER STORM WATCH EVERYWHERE
EXCEPT FOR TAYLOR WHICH LOOKS TOO FAR NORTH TO WARRANT A WATCH AT
THIS TIME. ON A SIDE NOTE...AFTER THE PRECIPITATION DIMINISHES TO
DRIZZLE...SETUP LOOKS FAVORABLE FOR FOG FORMATION. RECENT
PRECIPITATION PLUS DRYING ALOFT...LIGHT WINDS AND COLD GROUND ALL
SPELL FOG. ADDED AREAS OF FOG TO THE FORECAST AFTER MIDNIGHT SUNDAY
NIGHT.

MONDAY AND MONDAY NIGHT...MODELS SHOW THAT THE WESTERN TROUGH SLIDES
SLOWLY EASTWARD DURING THIS PERIOD...WITH A NEW LOW PRESSURE AREA
DEVELOPING OVER THE CENTRAL PLAINS. SUBSIDENCE IN THE WAKE OF THE
SUNDAY/SUNDAY NIGHT SYSTEM WILL LEAVE THE AREA DRY FOR MONDAY. NOTE
THAT THERE IS TRAPPED MOISTURE BELOW THE SUBSIDENCE INVERSION...BUT
26.00Z GFS/NAM SOUNDINGS DO NOT DEPICT ANY LIFT WITHIN THIS CLOUD
LAYER. THUS...THE SMALL PRECIPITATION CHANCES WERE REMOVED.
HOWEVER...FOG STILL LOOKS LIKE A GOOD BET FOR THE MORNING. SREF
VISIBILITY PROGS FOR LESS THAN 1 MILE ARE QUITE IMPRESSIVE AT 12Z
MONDAY WHEN LOOKING AT A REGIONAL PERSPECTIVE. WITH THE
PRECIPITATION SHUT OFF ON MONDAY...925MB TEMPS ARE REALLY ALLOWED TO
WARM...CLIMBING TO 0-4C BY 00Z TUESDAY. THUS...MOST LOCATIONS SHOULD
SEE HIGHS POP ABOVE FREEZING EVEN DESPITE THE CLOUDS. IN FACT...FAR
SOUTHERN AREAS COULD GET CLOSE TO 40. A NEW ROUND OF ISENTROPIC LIFT
STARTS UP MONDAY NIGHT AS THE LOW PRESSURE SYSTEM FORMS OVER THE
CENTRAL PLAINS. THERE ARE DIFFERENCES IN THE AMOUNT OF LIFT...BUT
THERE SHOULD BE ENOUGH TO SPREAD AT LEAST SOME LIGHT QPF ACROSS THE
AREA. GIVEN THAT MODEL FORECASTS HAVE THE NEAR SURFACE AIR COLD
ADVECTING WHILE THE AIR ALOFT SAY AT 850MB STAYS WARM (TEMPS ABOVE
2C)...CONCERNED THAT WE COULD END UP WITH FREEZING RAIN AND THUS
ADDED IT TO THE FORECAST.

.LONG TERM...TUESDAY THROUGH FRIDAY NIGHT
413 AM CST SAT JAN 26 2013

THE TWO BIG HIGHLIGHTS HERE ARE THE CENTRAL PLAINS SYSTEM FROM
MONDAY NIGHT AND THE CONSISTENT SURGE OF ARCTIC AIR PROGGED TOWARDS
THE MIDDLE OF THE WEEK. MODELS HAVE REALLY CHANGED THEIR TUNE FROM
YESTERDAY...NO LONGER CUTTING OFF THE SOUTHERN PORTION OF THE
WESTERN TROUGH. NOW THE WESTERN TROUGH IS SUGGESTED BY PRETTY MUCH
EVERY MODEL TO PROGRESS EASTWARD. AS IT DOES...THE CENTRAL PLAINS
LOW WILL LIFT NORTHEAST. THE BIG QUESTION MARK IS GOING TO BE
WATCHING HOW STRONG THIS LOW IS...WHICH DEPENDS ON HOW QUICK ARCTIC
AIR CAN COME DOWN INTO THE NORTHERN PLAINS. THE NEW 26.06Z GFS AND
TO SOME DEGREE THE 26.00Z CANADIAN PHASE THE TWO TOGETHER...
RESULTING IN A DEEP LOW. HOWEVER...THE ECMWF MAINTAINS A MORE
POSITIVELY TILTED LOOK...THUS A WEAKER LOW AND MUCH LESS QPF AND
WIND. NONETHELESS...CHANCES OF PRECIPITATION ARE REQUIRED FOR
TUESDAY THROUGH WEDNESDAY FOR THE BACK SIDE OF THE SYSTEM. IT IS
POSSIBLE TUESDAY WE COULD STILL BE DEALING WITH SNOW...RAIN...SLEET
AND FREEZING RAIN...BUT FOR NOW HAVE KEPT IT TO RAIN/SNOW. ARCTIC
AIR THEN RUSHES IN FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. 850MB
TEMPS PLUMMET TO -20 TO -24C. HIGH PRESSURE BUILDS IN FOR FRIDAY
WITH PERHAPS A NORTHWEST FLOW SYSTEM APPROACHING THE AREA FRIDAY
NIGHT.

&&

.AVIATION...THROUGH 18Z SUNDAY
1114 AM CST SAT JAN 26 2013

A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE CENTRAL PLAINS TONIGHT
AND PUSH NORTHEAST INTO THE UPPER MISSISSIPPI RIVER VALLEY LATE
SUNDAY MORNING INTO SUNDAY AFTERNOON. A MIX OF SNOW/SLEET/FREEZING
RAIN IS EXPECTED TO SPREAD INTO THE TAF SITES MAINLY AFTERNOON ON
SUNDAY WITH CONDITIONS DROPPING TO MVFR BY LATE SUNDAY MORNING
THEN INTO THE IFR TO LIFR CATEGORY SUNDAY AFTERNOON. ICE
ACCUMULATIONS AROUND 1/10 OF AN INCH ARE POSSIBLE. SNOW AND SLEET
ACCUMULATIONS OF 1 TO 3 INCHES ARE ALSO POSSIBLE. VFR CONDITIONS
ARE EXPECTED LATE THIS AFTERNOON THROUGH TONIGHT AS CLOUDS THICKEN
AHEAD OF THE APPROACHING SYSTEM. PLAN ON CEILINGS IN THE 5-8KFT
RANGE. THE CEILINGS WILL RAPIDLY LOWER LATE SUNDAY MORNING AS THE
LOW MOVES IN. SOUTH/SOUTHEAST WINDS WILL INCREASE ACROSS THE AREA
LATE THIS AFTERNOON INTO THIS EVENING INTO THE 10 TO 14 KT RANGE.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
413 AM CST SAT JAN 26 2013

WI...WINTER STORM WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
     FOR WIZ029-032>034-041>044-053>055-061.

MN...WINTER STORM WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
     FOR MNZ079-086>088-094>096.

IA...WINTER STORM WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
     FOR IAZ008>011-018-019-029-030.

&&

$$

SHORT TERM...AJ
LONG TERM....AJ
AVIATION...WETENKAMP