Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/16/12
AREA FORECAST DISCUSSION
NWS TUCSON AZ
845 PM MST SAT DEC 15 2012
.SYNOPSIS...AREAS OF VALLEY RAIN AND MOUNTAIN SNOW SHOWERS WILL
CONTINUE ACROSS THE AREA INTO SUNDAY AS THE LAST IN A SERIES OF
IMPULSES MOVES THROUGH THE STATE. COLD SUNDAY NIGHT AND MONDAY
MORNING BEFORE WARMER AND DRIER CONDITIONS MONDAY AND TUESDAY.
ANOTHER STRONG AND COLD PACIFIC STORM WILL BRING VALLEY RAIN AND
MOUNTAIN SNOW TO THE AREA LATE TUESDAY NIGHT INTO WEDNESDAY.
&&
.DISCUSSION...LOW LEVEL CONVERGENT AREA FOCUSING AND ENHANCING
SHOWER ACTIVITY THROUGH MUCH OF PINAL COUNTY. AREA SHIFTING EAST AND
STRETCHING ALONG A WEAK DEFORMATION AXIS AS THE FINAL IMPULSE PUSHES
THROUGH THE AREA IN THE MORNING. UPDATED FORECAST TO INCREASE
SHOWERS WITH LATEST HRRR AND 00Z NAM12 TRENDS KEEPING SOME SHOWER
ACTIVITY PAST 12Z. ALSO STARTED TO TWEAK THE WEDNESDAY STORM AS IT
IS SHAPING UP COLDER AND WETTER THAN PREVIOUSLY ADVERTISED. ONCE
EVERYTHING CLEARS OUT SUNDAY NIGHT...MONDAY MORNING COULD END UP
COLDER THAN CURRENT FORECAST TRENDS SUGGEST.
ECMWF SHOWING THE COLDEST NIGHT OF THE SEASON SO FAR WEDNESDAY NIGHT
INTO THURSDAY MORNING AND 12Z GFS WAS CATCHING UP TO THIS
IDEA...WE`LL SEE WHAT THE 00Z TRENDS SHOW. POTENTIALLY COULD END UP
WITH A WIDESPREAD HARD FREEZE THAT INCLUDES TUCSON METRO THURSDAY
MORNING.
&&
.PREV DISCUSSION...UPPER TROF CONTINUE TO PUSH EAST ACROSS THE STATE
THIS AFTERNOON. MAINLY ISOLATED LIGHT SHOWERS/MOUNTAIN SNOW SHOWERS
WERE OCCURRING THIS AFTERNOON ACROSS SE AZ. TRAILING FAST MOVING
SYSTEM WHICH IS CURRENTLY OVER CENTRAL CALIFORNIA...WILL PUSH ACROSS
THE AREA LATE TONIGHT INTO SUNDAY MORNING. SHOULD SEE AN INCREASE IN
AREAL COVERAGE OF SHOWERS...ESPECIALLY FROM TUCSON NORTH...TONIGHT
INTO SUNDAY MORNING. HAVE DECIDED TO EXTEND THE WINTER WEATHER
ADVISORY FOR THE MOUNTAINS FROM TUCSON NORTHEAST INTO THE WHITES
UNTIL MIDNIGHT FOR ANOTHER 3-7 INCHES. IF 18Z NAM IS CORRECT...THE
EVENING SHIFT MAY HAVE TO EXTEND ADVISORY OUT A LITTLE FURTHER.
CONDITIONS IMPROVING RAPIDLY SUNDAY FROM WEST TO EAST WITH PASSAGE
OF LATEST TROF WITH TEMPERATURES REMAINING ON THE COOL SIDE.
WARMER MONDAY/TUESDAY AS RIDGE BUILDS OVER THE AREA WITH HIGHS 5-7
DEGREES ABOVE NORMAL.
BOTH GFS/ECMWF MODELS ARE VERY CONSISTENT ON MOVING PACIFIC TROF
THROUGH THE STATE LATE TUESDAY NIGHT INTO WEDNESDAY. BASED ON THE
12Z MODEL OUTPUT AND ENSEMBLE RUNS...INCREASED POPS AREAWIDE INTO
CHANCE CATEGORY...LOWERED HIGH TEMPERATURES...AND BROUGHT DOWN SNOW
LEVELS. POPS LIKELY NOT HIGH ENOUGH BUT PLENTY OF TIME TO WORK ON
THEM.
COLDER WEDNESDAY NIGHT INTO THURSDAY MORNING...THUS LOWERED
INHERITED FORECAST LOW TEMPERATURES. COULD SEE FREEZING BACK INTO
THE TUCSON METRO AREA...BUT FOR NOW KEPT LOWS ABOVE FREEZING.
DRY AND WARMER THURSDAY INTO NEXT SATURDAY.
&&
.AVIATION...CIGS LOWERING TO 3-5K FT AGL AND LOCAL CIGS OF 2-3K FT
AGL. INCREASING SHRA/SHSN THROUGH 16/16Z THEN SOME CLEARING FROM THE
WEST. DECREASING SWLY WINDS GENERALLY LESS THAN 10 KTS BY 16/06Z.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...THE LAST IN A SERIES OF WEATHER SYSTEMS WILL BRING
INCREASING VALLEY RAIN AND MOUNTAIN SNOW SHOWERS OVERNIGHT. DRY AND
WARMER CONDITIONS ARE EXPECTED MONDAY AND TUESDAY...WITH YET ANOTHER
SYSTEM MOVING ACROSS ARIZONA WEDNESDAY.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY EXTENDED TO 12 AM MST SUNDAY FOR
AZZ510>511-514.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
MEYER/GLUECK
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
346 PM MST FRI DEC 14 2012
.SHORT TERM...UPPER TROUGH CURRENTLY MOVING ACROSS STATE WITH
SOUTHERLY FLOW ALOFT BECOMING MORE SOUTHWEST. QUITE A BIT OF
MOISTURE OVER AREA THOUGH WEB CAMS ACROSS MOUNTAINS INDICATING
MOST OF THE MOISTURE OVER THE RIDGES. DESPITE THE INCREASING MID
LEVEL ASCENT ASSOCIATED WITH THE TROUGH ALONG WITH LAPSE RATES
AROUND 6 C/KM...MOUNTAIN SNOW FALL HAS BEEN LIMITED AND CONFINED
TO THE HIGHER RIDGES. ACROSS PLAINS...PRECIPITATION HAS BEEN
CONFINED FAR NORTHEAST ZONES IN AREA OF LOWER SURFACE PRESSURE.
MODELS MOVE TROUGH INTO KANSAS WITH DURING THE EVENING WITH FLOW
ALOFT BECOMING WESTERLY. MID LEVEL ASCENT SHIFTS EAST WITH THE
TROUGH...WITH SUBSIDENCE SPREADING ACROSS STATE. MODEL CROSS
SECTIONS KEEP FAIRLY DEEP MOISTURE ACROSS MOUNTAINS. WITH
OROGRAPHICS BECOMING MORE FAVORABLE FOR SNOW FALL...SHOULD SEE A
BETTER CHANCE FOR SNOW. WILL KEEP ACCUMULATIONS LIGHT WITH THE
INCREASING SUBSIDENCE. ACROSS PLAINS....LATEST RUC KEEPS SOME
LIGHT QPF AND SNOW ACCUMUATION ACROSS THE FAR NORTHEAST SECTIONS
DURING THE EVENING...WITH DRY CONDITIONS AFTER MIDNIGHT. THIS
STILL SEEMS ON TRACK BASED ON TROUGH. WET BULB ZERO HEIGHTS
SUGGEST PRECIP TO BE MAINLY SNOW. ON SATURDAY...FLOW ALOFT BECOMES
WEST NORTHWEST WITH CONTINUED MOISTURE ACROSS MOUNTAINS. MODELS
SHOW NEXT SHORTWAVE MOVING INTO COLORADO DURING THE MORNING WITH
INCREASING MID LEVEL ASCENT. THIS WILL KEEP AT LEAST A CHANCE OF
MOUNTAIN SNOW ONGOING WHICH MAY BE ENHANCED DURING THE AFTERNOON
AS LAPSE RATES INCREASE TO AROUND 6 C/KM. AMOUNTS SHOULD REMAIN
BELOW ADVISORY CRITERIA. ACROSS PLAINS...CLOUDS TO INCREASE DURING
THE MORNING AS SURFACE WINDS BECOME NORTHWEST. WITH MID LEVEL
ASCENT MOVING INTO THE AREA...COULD SEE SOME SHOWERS MOVE OFF THE
FOOTHILLS ACROSS THE NORTHERN PLAINS DURING THE AFTERNOON. MODELS
SHOW THE SHOWERS CONFINED TO AREAS NORTH AND EAST OF DENVER.
LATEST GFS SHOWING WINDS BECOMING NORTHEAST AFTER 21Z WHICH COULD
HELP INCREASE PRECIP CHANCES. FOR NOW WILL MAINTAIN THE SLIGHT
CHANCE. FORECAST SOUNDINGS SUGGEST TEMPERATURES TO BE WARM ENOUGH
FOR RAIN RATHER THAN SNOW.
.LONG TERM...A PROGRESSIVE UPPER LEVEL FLOW PATTERN WILL DOMINATE
THE WEATHER THROUGH EARLY NEXT WEEK...BEFORE AN UPPER RIDGE
DEVELOPS THROUGH THE MIDDLE OF THE WEEK. THE WESTERLY FLOW ALOFT
WILL BRING WEAK SHOTS OF MOISTURE TO THE MOUNTAINS AS EMBEDDED
SHORT WAVE TROUGHS PASS OVER THE STATE. THE PLAINS WILL BE LEFT
WITH CONTINUED DRY...DOWNSLOPING FLOW. THE FIRST UPPER TROUGH TO
MOVE OVER THE STATE WILL BE SATURDAY NIGHT AND SUNDAY MORNING.
EARLY IN THE WEEK...SOME DRYING WILL OCCUR AS ZONAL FLOW CONTINUES
OVER THE STATE. THE NEXT...STRONGER TROUGH WILL BE MOVING OVER THE
STATE ON WEDNESDAY AND WEDNESDAY NIGHT. THIS SYSTEM MAY HAVE
ENOUGH AMPLITUDE TO PRODUCE SOME PRECIPITATION ON THE PLAINS...
BUT WILL NEED TO SEE HOW LATER MODEL RUNS HANDLE THE DEVELOPMENT
OF THE TROUGH. FOR NOW WILL ONLY MENTION SNOW IN THE MOUNTAIN
AREAS. AFTER THE MID-WEEK TROUGH...THE ECMWF AND GFS SHOW STRONGER
RIDGING OVER THE WESTERN U.S. WHICH WILL BRING WARMER TEMPERATURES
TO THE REGION.
&&
.AVIATION...PRECIPITATION CONFINED TO EASTERN PLAINS EAST OF
DENVER. AS SYSTEM MOVES EAST OF COLORADO...PRECIP TO HEAD EAST AS
WELL. VFR TO CONTINUE...NOT ANTICIPATING CEILINGS TO LOWER TO 6000
FEET AGL AT THIS TIME. LIGHT EASTERLY WINDS TO BECOME SOUTHERLY AS
DRAINAGE FLOW DEVELOPS...WITH A WESTERLY COMPONENT AT BJC. SPEEDS
TO REMAIN AROUND 8 KTS. ON SATURDAY...WINDS TO BECOME NORTHWEST BY
16Z. A FEW RAIN SHOWERS ARE POSSIBLE DURING THE AFTERNOON..WITH
POSSIBLE CEILINGS AROUND 6000 FEET AGL.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....DANKERS
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
940 AM MST FRI DEC 14 2012
.UPDATE...
&&
.SHORT TERM...UPPER TROUGH MOVING INTO COLORADO WITH MOIST SOUTHERLY
FLOW ALOFT ACROSS AREA. RADAR SHOWING SNOW BEGINNING TO SPREAD
INTO SOUTH PARK. WEB CAMS INDICATING SOME OBSCURRED RIDGES ALONG
THE CONTINENTAL DIVIDE OF SUMMIT COUNTY...WITH PERHAPS SOME LIGHT
SNOW THERE. UPPER TROUGH STILL PROGGED TO MOVE QUICKLY NORTHEAST
ACROSS THE AREA TROUGH THE AFTERNOON WITH INCREASING MID LEVEL QG
ASCENT AND LAPSE RATES. THUS A GOOD CHANCE OF SNOW STILL IN LINE
FOR THE MOUNTAINS...THOUGH FLOW NOT FAVORABLE FOR DECENT AMOUNTS.
ACROSS PLAINS...SURFACE LOW ALONG FOOTHILLS TO MOVE TOWARD THE
NEBRASKA-KANSAS BORDER DURING THE AFTERNOON. THIS TO PROVIDE SOME
LOCAL DOWNSLOPE FLOW ACROSS URBAN CORRIDOR WHICH COULD LIMIT
PRECIP CHANCES. OVERALL...THE LATEST MODELS SHOW BEST CHANCE FOR
PRECIP TOWARDS THE EASTERN COLORADO BORDER. FORECAST SOUNDING
STILL INDICATING A POSSIBILITY OF A RAIN AND SNOW MIX ACROSS THE
LOWER ELEVATIONS...STILL SEEM REASONABLE EVEN WITH HIGHS EXPECTED
TO BE IN THE LOWER AND MIDDLE 40S. CURRENT FORECASTS STILL SEEM
ON TRACK...ONLY MINOR ADJUSTMENTS AT THIS TIME.
.AVIATION...CURRENT FORECASTS SEEM ON TRACK. LATEST HRRR AND RAP
INDICATING PRECIPITATION MOVING ACROSS THE DENVER AREA AROUND 18Z
WHILE THE OTHER MODELS KEEP THE PRECIP EAST OF THE AREA AIRPORTS.
LATEST RADAR IS SHOWING SOME PRECIP MOVING INTO SOUTHERN DOUGLAS
COUNTY. FOR NOW WILL CONTINUE WITH A VCSH AND UPDATE AS NEEDED.
CEILINGS MAY NEED TO BE LOWERED IF SHOWERS SPREAD ACROSS THE AREA
AIRPORTS.
&&
.PREV DISCUSSION... /ISSUED 412 AM MST FRI DEC 14 2012/
SHORT TERM...AN UPPER LEVEL TROUGH OVER THE SWRN US WILL EJECT
QUICKLY ACROSS THE AREA THIS AFTN THRU THE EARLY EVENING HOURS. QG
FIELDS SHOW SOME MID LVL ASCENT AS SYSTEM MOVES ACROSS ALTHOUGH
WITH LAPSE RATES AROUND 6 C/KM. OVERALL FLOW IN THE MTNS WILL BE
SLY THRU THE AFTN AND THEN BECOME MORE WNW THIS EVENING AS THE
UPPER LEVEL TROUGH PASSES. THUS SHOULD SEE SOME SNOW ESPECIALLY
AS OROGRAPHIC COMPONENT BECOMES BETTER BY EARLY THIS EVENING WITH
SOME LIGHT ACCUMULATIONS. OVER NERN CO SFC LOW PRESSURE WILL
DEVELOP OVER THE AREA TODAY AND THEN MOVE INTO THE CNTRL PLAINS BY
TONIGHT. OVERALL SFC PTRN IS NOT REAL FAVORABLE FOR PCPN HOWEVER
WITH INCREASING MOISTURE AND MID LVL ASCENT WITH UPPER LEVEL
TROUGH WILL SEE A CHC OF PCPN MOSTLY OVER THE PLAINS. THE RAP
MODEL KEEPS A CHC OF PCPN CLOSER TO THE FOOTHILLS IN THE AFTN
WHILE ALL OF THE OTHER MODELS ARE CONSIDERABLY DRIER. FOR NOW WILL
JUST MENTION A SLIGHT CHC OF PCPN AROUND DENVER AND KEEP AREAS
FURTHER NORTH DRY. WET BULB ZEROS WOULD SUGGEST A MIXTURE OF RAIN
AND SNOW AT LOWER ELEVATIONS THIS AFTN WITH A MAINLY SNOW THIS
EVENING. AS FOR HIGHS WITH CONSIDERABLE CLOUD COVER AND SOME
COLLING OCCURRING IN THE LOWER LEVELS WILL KEEP HIGHS IN THE LOWER
TO MID 40S ACROSS NERN CO.
FOR TONIGHT THE UPPER LEVEL TROUGH WILL MOVE QUICKLY EAST OF THE
AREA WITH SOME LINGERING SNOW OVER THE FAR NERN PLAINS THROUGH
MIDNIGHT BEFORE ENDING. IN THE MTNS WILL CONTINUE TO SEE SOME
OROGRAPHIC SNOW OVERNIGHT.
LONG TERM...FIRST IN A SERIES OF SHORTWAVE TROUGHS WHISKED ALONG BY
A MODERATELY STRONG WESTERLY FLOW ALOFT SHOULD BE WELL EAST OF THE
STATE BY SATURDAY MORNING. WEST-NORTHWESTERLY LOW-LEVEL FLOW DURING
THE MORNING HOURS AIDS IN DRYING THE BOUNDARY LAYER EAST OF THE
MTNS. SHOULD SEE A FAIR AMOUNT OF SUNSHINE TO START THE DAY BEFORE
THE RETURN OF MOSTLY CLOUDY SKIES IN THE AFTERNOON AS THE NEXT IN
THE SERIES OF SHORTWAVE TROUGH WHICH MODELS SHOW TRAVERSING THE
STATE LATE SATURDAY AFTERNOON AND OVERNIGHT. THIS WAVE APPEARS TO DE-
AMPLIFY SOME AS IT PASSES OVER THE AREA SATURDAY EVENING. AS THIS IS
GOING ON...MODELS ALSO SHOW A WEAK COLD FRONT BACKING INTO NERN
COLORADO WHICH CAUSES W-NWLY SFC WINDS TO TURN N-NELY FOR SEVERAL
HOURS IN THE EVENING. MODELS...PARTICULARLY THE GFS...SHOW A BAND OF
LIGHT PCPN FORMING ALONG THIS FRONTAL BOUNDARY AS IT SLIPS S-
SWWRD...POSSIBLY AS FAR WEST AS EASTERN PORTIONS OF THE DENVER METRO
AREA BY ERLY IN THE EVENING. SHWRS UP ALONG THE WYOMING BORDER IN
THE AFTERNOON SHOULD START OUT AS RAIN WITH TEMPS IN THE 40S. THEN
AS TEMPS FALL AND SHOWERS BECOME A BIT MORE NUMEROUS FARTHER
SOUTH...PCPN IS EXPECTED TO CHANGE TO A RAIN/SNOW MIX IN THE
EVENING. COULD SEE A FEW POCKETS OF VERY LIGHT SNOW ACCUMULATION
WELL EAST OF THE I-25 CORRIDOR...BUT OVERALL NOT LOOKING FOR ANY
ACCUMULATION ON THE PLAINS. IN THE HIGH COUNTRY...SCATTERED TO
LIKELY POPS ARE IN ORDER THROUGHOUT THE DAY...WITH THE BEST CHANCE
FOR MEASURABLE SNOW ONCE AGAIN ALONG AND WEST OF THE CONTINENTAL
DIVIDE DUE TO THE WESTERLY FLOW AT MTN TOP LEVEL. THIS SYSTEM DOES
NOT LOOK LIKE A BIG SNOW PRODUCER FOR OUR PART OF THE
STATE...PROBABLY NO MORE THAN 3-4 INCHES AT BEST ON WINDWARD SLOPES
AND PERHAPS AN INCH OR SO ON THE VALLEY FLOORS BY LATE SATURDAY
EVENING.
ANOTHER UPPER AIR SYSTEM...THOUGH NOT AS STRONG AS ITS TWO
PREDECESSORS...DROPS IN FROM IDAHO/NRN UTAH DURING THE DAY SUNDAY
BRINGS YET ANOTHER SHOT OF SNOWFALL TO THE NORTH-CENTRAL MOUNTAINS
BY SUNDAY AFTERNOON AND EVENING...AND POSSIBLY A FEW RAIN/SNOW
SHOWERS TO THE NERN CORNER OF THE STATE BY EVENING. AGAIN...
NORTHWEST FACING MTN SLOPES COULD PICK UP ANOTHER FEW INCHES OF
SNOW...WITH PERHAPS AN INCH OF SNOW ON VALLEY FLOORS... AND NO
ACCUMULATION ON THE PLAINS. THIS WEATHER MAKER IS FORECAST TO
QUICKLY MOVE OUT BY MONDAY MORNING AS A STRONG HIGH PRESSURE RIDGE
BUILDS IN OVER THE GREAT BASIN. THIS RIDGE MOVES EAST ON MONDAY AND
TRAVERSES THE STATE ON TUESDAY PRODUCING PROBABLY THE WARMEST
TEMPERATURES OF THE WEEK ALONG WITH A DECENT AMOUNT OF
SUNSHINE...ESPLY EAST OF THE MTNS. BY WEDNESDAY...MEDIUM RANGE
MODELS SHOW YET ANOTHER TROUGH SWINGING ACROSS THE REGION FROM THE
CENTRAL GREAT BASIN...POTENTIALLY BRINGING MORE SNOW TO THE HIGH
COUNTRY AND POSSIBLY A FEW RAIN SHOWERS TO LOWER ELEVATIONS.
AVIATION...RAP SHOWS A CHC OF A RAIN/SNOW SHOWERS THIS AFTN WHILE THE
NAM AND GFS KEEP MOST OF THE ACTIVITY EAST OF THE AIRPORT. FOR
NOW WILL JUST MENTION VCTY IN THE TAF. WILL HAVE CONSIDERABLE MID
AND HIGH LVL CLOUDS THRU THE DAY WITH CEILINGS LOWERING TO 8000 FT
BY EARLY AFTN. THE NAM AND RAP HAVE LOWER CEILINGS DOWN TO 5000 FT
OR SO BY AFTN BUT WILL KEEP THEM AROUND 8000 FT FOR NOW. AS FOR
WINDS A SFC LOW HS FORMED EARLY THIS MORNING NR DENVER WITH LIGHT
WLY WINDS AT THE AIRPORT. THE LATEST RAP KEEPS THIS LOW NR DENVER
THRU AFTN WITH VARIABLE WIND DIRECTIONS. FOR NOW WILL HAVE THEM
TRENDING LIGHT ELY BY LATE MORNING THRU MID AFTN AND THEN BECOMING
MORE NLY BY 00Z. BY EARLY EVENING WILL HAVE NWLY WINDS FOR A FEW
HOURS AND THEN MORE WSW BY 06Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....BAKER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
412 AM MST FRI DEC 14 2012
.SHORT TERM...AN UPPER LEVEL TROUGH OVER THE SWRN US WILL EJECT
QUICKLY ACROSS THE AREA THIS AFTN THRU THE EARLY EVENING HOURS. QG
FIELDS SHOW SOME MID LVL ASCENT AS SYSTEM MOVES ACROSS ALTHOUGH
WITH LAPSE RATES AROUND 6 C/KM. OVERALL FLOW IN THE MTNS WILL BE
SLY THRU THE AFTN AND THEN BECOME MORE WNW THIS EVENING AS THE
UPPER LEVEL TROUGH PASSES. THUS SHOULD SEE SOME SNOW ESPECIALLY
AS OROGRAPHIC COMPONENT BECOMES BETTER BY EARLY THIS EVENING WITH
SOME LIGHT ACCUMULATIONS. OVER NERN CO SFC LOW PRESSURE WILL
DEVELOP OVER THE AREA TODAY AND THEN MOVE INTO THE CNTRL PLAINS BY
TONIGHT. OVERALL SFC PTRN IS NOT REAL FAVORABLE FOR PCPN HOWEVER
WITH INCREASING MOISTURE AND MID LVL ASCENT WITH UPPER LEVEL
TROUGH WILL SEE A CHC OF PCPN MOSTLY OVER THE PLAINS. THE RAP
MODEL KEEPS A CHC OF PCPN CLOSER TO THE FOOTHILLS IN THE AFTN
WHILE ALL OF THE OTHER MODELS ARE CONSIDERABLY DRIER. FOR NOW WILL
JUST MENTION A SLIGHT CHC OF PCPN AROUND DENVER AND KEEP AREAS
FURTHER NORTH DRY. WET BULB ZEROS WOULD SUGGEST A MIXTURE OF RAIN
AND SNOW AT LOWER ELEVATIONS THIS AFTN WITH A MAINLY SNOW THIS
EVENING. AS FOR HIGHS WITH CONSIDERABLE CLOUD COVER AND SOME
COLLING OCCURRING IN THE LOWER LEVELS WILL KEEP HIGHS IN THE LOWER
TO MID 40S ACROSS NERN CO.
FOR TONIGHT THE UPPER LEVEL TROUGH WILL MOVE QUICKLY EAST OF THE
AREA WITH SOME LINGERING SNOW OVER THE FAR NERN PLAINS THROUGH
MIDNIGHT BEFORE ENDING. IN THE MTNS WILL CONTINUE TO SEE SOME
OROGRAPHIC SNOW OVERNIGHT.
.LONG TERM...FIRST IN A SERIES OF SHORTWAVE TROUGHS WHISKED ALONG BY
A MODERATELY STRONG WESTERLY FLOW ALOFT SHOULD BE WELL EAST OF THE
STATE BY SATURDAY MORNING. WEST-NORTHWESTERLY LOW-LEVEL FLOW DURING
THE MORNING HOURS AIDS IN DRYING THE BOUNDARY LAYER EAST OF THE
MTNS. SHOULD SEE A FAIR AMOUNT OF SUNSHINE TO START THE DAY BEFORE
THE RETURN OF MOSTLY CLOUDY SKIES IN THE AFTERNOON AS THE NEXT IN
THE SERIES OF SHORTWAVE TROUGH WHICH MODELS SHOW TRAVERSING THE
STATE LATE SATURDAY AFTERNOON AND OVERNIGHT. THIS WAVE APPEARS TO DE-
AMPLIFY SOME AS IT PASSES OVER THE AREA SATURDAY EVENING. AS THIS IS
GOING ON...MODELS ALSO SHOW A WEAK COLD FRONT BACKING INTO NERN
COLORADO WHICH CAUSES W-NWLY SFC WINDS TO TURN N-NELY FOR SEVERAL
HOURS IN THE EVENING. MODELS...PARTICULARLY THE GFS...SHOW A BAND OF
LIGHT PCPN FORMING ALONG THIS FRONTAL BOUNDARY AS IT SLIPS S-
SWWRD...POSSIBLY AS FAR WEST AS EASTERN PORTIONS OF THE DENVER METRO
AREA BY ERLY IN THE EVENING. SHWRS UP ALONG THE WYOMING BORDER IN
THE AFTERNOON SHOULD START OUT AS RAIN WITH TEMPS IN THE 40S. THEN
AS TEMPS FALL AND SHOWERS BECOME A BIT MORE NUMEROUS FARTHER
SOUTH...PCPN IS EXPECTED TO CHANGE TO A RAIN/SNOW MIX IN THE
EVENING. COULD SEE A FEW POCKETS OF VERY LIGHT SNOW ACCUMULATION
WELL EAST OF THE I-25 CORRIDOR...BUT OVERALL NOT LOOKING FOR ANY
ACCUMULATION ON THE PLAINS. IN THE HIGH COUNTRY...SCATTERED TO
LIKELY POPS ARE IN ORDER THROUGHOUT THE DAY...WITH THE BEST CHANCE
FOR MEASURABLE SNOW ONCE AGAIN ALONG AND WEST OF THE CONTINENTAL
DIVIDE DUE TO THE WESTERLY FLOW AT MTN TOP LEVEL. THIS SYSTEM DOES
NOT LOOK LIKE A BIG SNOW PRODUCER FOR OUR PART OF THE
STATE...PROBABLY NO MORE THAN 3-4 INCHES AT BEST ON WINDWARD SLOPES
AND PERHAPS AN INCH OR SO ON THE VALLEY FLOORS BY LATE SATURDAY
EVENING.
ANOTHER UPPER AIR SYSTEM...THOUGH NOT AS STRONG AS ITS TWO
PREDECESSORS...DROPS IN FROM IDAHO/NRN UTAH DURING THE DAY SUNDAY
BRINGS YET ANOTHER SHOT OF SNOWFALL TO THE NORTH-CENTRAL MOUNTAINS
BY SUNDAY AFTERNOON AND EVENING...AND POSSIBLY A FEW RAIN/SNOW
SHOWERS TO THE NERN CORNER OF THE STATE BY EVENING. AGAIN...
NORTHWEST FACING MTN SLOPES COULD PICK UP ANOTHER FEW INCHES OF
SNOW...WITH PERHAPS AN INCH OF SNOW ON VALLEY FLOORS... AND NO
ACCUMULATION ON THE PLAINS. THIS WEATHER MAKER IS FORECAST TO
QUICKLY MOVE OUT BY MONDAY MORNING AS A STRONG HIGH PRESSURE RIDGE
BUILDS IN OVER THE GREAT BASIN. THIS RIDGE MOVES EAST ON MONDAY AND
TRAVERSES THE STATE ON TUESDAY PRODUCING PROBABLY THE WARMEST
TEMPERATURES OF THE WEEK ALONG WITH A DECENT AMOUNT OF
SUNSHINE...ESPLY EAST OF THE MTNS. BY WEDNESDAY...MEDIUM RANGE
MODELS SHOW YET ANOTHER TROUGH SWINGING ACROSS THE REGION FROM THE
CENTRAL GREAT BASIN...POTENTIALLY BRINGING MORE SNOW TO THE HIGH
COUNTRY AND POSSIBLY A FEW RAIN SHOWERS TO LOWER ELEVATIONS.
&&
.AVIATION...RAP SHOWS A CHC OF A RAIN/SNOW SHOWERS THIS AFTN WHILE THE
NAM AND GFS KEEP MOST OF THE ACTIVITY EAST OF THE AIRPORT. FOR
NOW WILL JUST MENTION VCTY IN THE TAF. WILL HAVE CONSIDERABLE MID
AND HIGH LVL CLOUDS THRU THE DAY WITH CEILINGS LOWERING TO 8000 FT
BY EARLY AFTN. THE NAM AND RAP HAVE LOWER CEILINGS DOWN TO 5000 FT
OR SO BY AFTN BUT WILL KEEP THEM AROUND 8000 FT FOR NOW. AS FOR
WINDS A SFC LOW HS FORMED EARLY THIS MORNING NR DENVER WITH LIGHT
WLY WINDS AT THE AIRPORT. THE LATEST RAP KEEPS THIS LOW NR DENVER
THRU AFTN WITH VARIABLE WIND DIRECTIONS. FOR NOW WILL HAVE THEM
TRENDING LIGHT ELY BY LATE MORNING THRU MID AFTN AND THEN BECOMING
MORE NLY BY 00Z. BY EARLY EVENING WILL HAVE NWLY WINDS FOR A FEW
HOURS AND THEN MORE WSW BY 06Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
359 AM MST FRI DEC 14 2012
.SHORT TERM...SOUTHWEST FLOW ALOFT WILL KEEP RELATIVELY MILD
TEMPERATURES IN PLACE OVERNIGHT. CLOUDS WILL BEGIN TO INCREASE AND
THICKEN LATE TONIGHT AS UPPER LEVEL MOISTURE FROM NEXT UPPER
TROUGH MOVES THIS WAY. THIS UPPER LEVEL TROUGH KICKS RATHER
QUICKLY EASTWARD FROM CALIFORNIA INTO THE DESERT SOUTHWEST LATE
TONIGHT INTO EARLY FRIDAY MORNING. THE MAIN PIECE OF ENERGY THEN
SHIFTS QUICKLY NORTHEAST ACROSS THE EASTERN PLAINS OF COLORADO BY
FRIDAY AFTERNOON. WHILE MOST OF THE CWA WILL HAVE UPWARD Q-G
VERTICAL MOTION...THE DEEPEST MOISTURE IS STILL ADVERTISED TO PUSH
ACROSS THE EASTERN PLAINS. AS A RESULT...WILL BUMP UP POPS A BIT
MORE IN THE LIMON-AKRON-JULESBURG AREAS WHILE KEEPING MAINLY DRY
CONDITIONS IN THE I-25 CORRIDOR FROM DENVER TO THE WYOMING BORDER.
CANT RULE OUT A LITTLE SNOW MIXED IN AT TIMES ON THE PLAINS BUT
NO APPRECIABLE ACCUMULATION EXPECTED WITH SURFACE TEMPS HOLDING
ABOVE FREEZING AND GENERALLY LIGHT QPF OF 0.10 INCH OR LESS. THE
MOUNTAINS MAY ALSO BE ON THE NORTHERN EDGE OF THE MOISTURE BUT
GIVEN ELEVATION WILL KEEP MODEST POPS IN PLACE THERE...ESPECIALLY
FROM I-70 CORRIDOR SOUTHWARD.
.LONG TERM...FIRST IN A SERIES OF SHORTWAVE TROUGHS WHISKED ALONG BY
A MODERATELY STRONG WESTERLY FLOW ALOFT SHOULD BE WELL EAST OF THE
STATE BY SATURDAY MORNING. WEST-NORTHWESTERLY LOW-LEVEL FLOW DURING
THE MORNING HOURS AIDS IN DRYING THE BOUNDARY LAYER EAST OF THE
MTNS. SHOULD SEE A FAIR AMOUNT OF SUNSHINE TO START THE DAY BEFORE
THE RETURN OF MOSTLY CLOUDY SKIES IN THE AFTERNOON AS THE NEXT IN
THE SERIES OF SHORTWAVE TROUGH WHICH MODELS SHOW TRAVERSING THE
STATE LATE SATURDAY AFTERNOON AND OVERNIGHT. THIS WAVE APPEARS TO DE-
AMPLIFY SOME AS IT PASSES OVER THE AREA SATURDAY EVENING. AS THIS IS
GOING ON...MODELS ALSO SHOW A WEAK COLD FRONT BACKING INTO NERN
COLORADO WHICH CAUSES W-NWLY SFC WINDS TO TURN N-NELY FOR SEVERAL
HOURS IN THE EVENING. MODELS...PARTICULARLY THE GFS...SHOW A BAND OF
LIGHT PCPN FORMING ALONG THIS FRONTAL BOUNDARY AS IT SLIPS S-
SWWRD...POSSIBLY AS FAR WEST AS EASTERN PORTIONS OF THE DENVER METRO
AREA BY ERLY IN THE EVENING. SHWRS UP ALONG THE WYOMING BORDER IN
THE AFTERNOON SHOULD START OUT AS RAIN WITH TEMPS IN THE 40S. THEN
AS TEMPS FALL AND SHOWERS BECOME A BIT MORE NUMEROUS FARTHER
SOUTH...PCPN IS EXPECTED TO CHANGE TO A RAIN/SNOW MIX IN THE
EVENING. COULD SEE A FEW POCKETS OF VERY LIGHT SNOW ACCUMULATION
WELL EAST OF THE I-25 CORRIDOR...BUT OVERALL NOT LOOKING FOR ANY
ACCUMULATION ON THE PLAINS. IN THE HIGH COUNTRY...SCATTERED TO
LIKELY POPS ARE IN ORDER THROUGHOUT THE DAY...WITH THE BEST CHANCE
FOR MEASURABLE SNOW ONCE AGAIN ALONG AND WEST OF THE CONTINENTAL
DIVIDE DUE TO THE WESTERLY FLOW AT MTN TOP LEVEL. THIS SYSTEM DOES
NOT LOOK LIKE A BIG SNOW PRODUCER FOR OUR PART OF THE
STATE...PROBABLY NO MORE THAN 3-4 INCHES AT BEST ON WINDWARD SLOPES
AND PERHAPS AN INCH OR SO ON THE VALLEY FLOORS BY LATE SATURDAY
EVENING.
ANOTHER UPPER AIR SYSTEM...THOUGH NOT AS STRONG AS ITS TWO
PREDECESSORS...DROPS IN FROM IDAHO/NRN UTAH DURING THE DAY SUNDAY
BRINGS YET ANOTHER SHOT OF SNOWFALL TO THE NORTH-CENTRAL MOUNTAINS
BY SUNDAY AFTERNOON AND EVENING...AND POSSIBLY A FEW RAIN/SNOW
SHOWERS TO THE NERN CORNER OF THE STATE BY EVENING. AGAIN...
NORTHWEST FACING MTN SLOPES COULD PICK UP ANOTHER FEW INCHES OF
SNOW...WITH PERHAPS AN INCH OF SNOW ON VALLEY FLOORS... AND NO
ACCUMULATION ON THE PLAINS. THIS WEATHER MAKER IS FORECAST TO
QUICKLY MOVE OUT BY MONDAY MORNING AS A STRONG HIGH PRESSURE RIDGE
BUILDS IN OVER THE GREAT BASIN. THIS RIDGE MOVES EAST ON MONDAY AND
TRAVERSES THE STATE ON TUESDAY PRODUCING PROBABLY THE WARMEST
TEMPERATURES OF THE WEEK ALONG WITH A DECENT AMOUNT OF
SUNSHINE...ESPLY EAST OF THE MTNS. BY WEDNESDAY...MEDIUM RANGE
MODELS SHOW YET ANOTHER TROUGH SWINGING ACROSS THE REGION FROM THE
CENTRAL GREAT BASIN...POTENTIALLY BRINGING MORE SNOW TO THE HIGH
COUNTRY AND POSSIBLY A FEW RAIN SHOWERS TO LOWER ELEVATIONS.
&&
.AVIATION...RAP SHOWS A CHC OF A RAIN/SNOW SHOWERS THIS AFTN WHILE
THE NAM AND GFS KEEP MOST OF THE ACTIVITY EAST OF THE AIRPORT. FOR
NOW WILL JUST MENTION VCTY IN THE TAF. WILL HAVE CONSIDERABLE MID
AND HIGH LVL CLOUDS THRU THE DAY WITH CEILINGS LOWERING TO 8000 FT
BY EARLY AFTN. THE NAM AND RAP HAVE LOWER CEILINGS DOWN TO 5000 FT
OR SO BY AFTN BUT WILL KEEP THEM AROUND 8000 FT FOR NOW. AS FOR
WINDS A SFC LOW HS FORMED EARLY THIS MORNING NR DENVER WITH LIGHT
WLY WINDS AT THE AIRPORT. THE LATEST RAP KEEPS THIS LOW NR DENVER
THRU AFTN WITH VARIABLE WIND DIRECTIONS. FOR NOW WILL HAVE THEM
TRENDING LIGHT ELY BY LATE MORNING THRU MID AFTN AND THEN BECOMING
MORE NLY BY 00Z. BY EARLY EVENING WILL HAVE NWLY WINDS FOR A FEW
HOURS AND THEN MORE WSW BY 06Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES... NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
AVIATION...RPK
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER/BOULDER CO
312 PM MST THU DEC 13 2012
.SHORT TERM...SOUTHWEST FLOW ALOFT WILL KEEP RELATIVELY MILD
TEMPERATURES IN PLACE OVERNIGHT. CLOUDS WILL BEGIN TO INCREASE AND
THICKEN LATE TONIGHT AS UPPER LEVEL MOISTURE FROM NEXT UPPER
TROUGH MOVES THIS WAY. THIS UPPER LEVEL TROUGH KICKS RATHER
QUICKLY EASTWARD FROM CALIFORNIA INTO THE DESERT SOUTHWEST LATE
TONIGHT INTO EARLY FRIDAY MORNING. THE MAIN PIECE OF ENERGY THEN
SHIFTS QUICKLY NORTHEAST ACROSS THE EASTERN PLAINS OF COLORADO BY
FRIDAY AFTERNOON. WHILE MOST OF THE CWA WILL HAVE UPWARD Q-G
VERTICAL MOTION...THE DEEPEST MOISTURE IS STILL ADVERTISED TO PUSH
ACROSS THE EASTERN PLAINS. AS A RESULT...WILL BUMP UP POPS A BIT
MORE IN THE LIMON-AKRON-JULESBURG AREAS WHILE KEEPING MAINLY DRY
CONDITIONS IN THE I-25 CORRIDOR FROM DENVER TO THE WYOMING BORDER.
CANT RULE OUT A LITTLE SNOW MIXED IN AT TIMES ON THE PLAINS BUT
NO APPRECIABLE ACCUMULATION EXPECTED WITH SURFACE TEMPS HOLDING
ABOVE FREEZING AND GENERALLY LIGHT QPF OF 0.10 INCH OR LESS. THE
MOUNTAINS MAY ALSO BE ON THE NORTHERN EDGE OF THE MOISTURE BUT
GIVEN ELEVATION WILL KEEP MODEST POPS IN PLACE THERE...ESPECIALLY
FROM I-70 CORRIDOR SOUTHWARD.
.LONG TERM...FIRST IN A SERIES OF SHORTWAVE TROUGHS WHISKED ALONG BY
A MODERATELY STRONG WESTERLY FLOW ALOFT SHOULD BE WELL EAST OF THE
STATE BY SATURDAY MORNING. WEST-NORTHWESTERLY LOW-LEVEL FLOW DURING
THE MORNING HOURS AIDS IN DRYING THE BOUNDARY LAYER EAST OF THE
MTNS. SHOULD SEE A FAIR AMOUNT OF SUNSHINE TO START THE DAY BEFORE
THE RETURN OF MOSTLY CLOUDY SKIES IN THE AFTERNOON AS THE NEXT IN
THE SERIES OF SHORTWAVE TROUGH WHICH MODELS SHOW TRAVERSING THE
STATE LATE SATURDAY AFTERNOON AND OVERNIGHT. THIS WAVE APPEARS TO DE-
AMPLIFY SOME AS IT PASSES OVER THE AREA SATURDAY EVENING. AS THIS IS
GOING ON...MODELS ALSO SHOW A WEAK COLD FRONT BACKING INTO NERN
COLORADO WHICH CAUSES W-NWLY SFC WINDS TO TURN N-NELY FOR SEVERAL
HOURS IN THE EVENING. MODELS...PARTICULARLY THE GFS...SHOW A BAND OF
LIGHT PCPN FORMING ALONG THIS FRONTAL BOUNDARY AS IT SLIPS S-
SWWRD...POSSIBLY AS FAR WEST AS EASTERN PORTIONS OF THE DENVER METRO
AREA BY ERLY IN THE EVENING. SHWRS UP ALONG THE WYOMING BORDER IN
THE AFTERNOON SHOULD START OUT AS RAIN WITH TEMPS IN THE 40S. THEN
AS TEMPS FALL AND SHOWERS BECOME A BIT MORE NUMEROUS FARTHER
SOUTH...PCPN IS EXPECTED TO CHANGE TO A RAIN/SNOW MIX IN THE
EVENING. COULD SEE A FEW POCKETS OF VERY LIGHT SNOW ACCUMULATION
WELL EAST OF THE I-25 CORRIDOR...BUT OVERALL NOT LOOKING FOR ANY
ACCUMULATION ON THE PLAINS. IN THE HIGH COUNTRY...SCATTERED TO
LIKELY POPS ARE IN ORDER THROUGHOUT THE DAY...WITH THE BEST CHANCE
FOR MEASURABLE SNOW ONCE AGAIN ALONG AND WEST OF THE CONTINENTAL
DIVIDE DUE TO THE WESTERLY FLOW AT MTN TOP LEVEL. THIS SYSTEM DOES
NOT LOOK LIKE A BIG SNOW PRODUCER FOR OUR PART OF THE
STATE...PROBABLY NO MORE THAN 3-4 INCHES AT BEST ON WINDWARD SLOPES
AND PERHAPS AN INCH OR SO ON THE VALLEY FLOORS BY LATE SATURDAY
EVENING.
ANOTHER UPPER AIR SYSTEM...THOUGH NOT AS STRONG AS ITS TWO
PREDECESSORS...DROPS IN FROM IDAHO/NRN UTAH DURING THE DAY SUNDAY
BRINGS YET ANOTHER SHOT OF SNOWFALL TO THE NORTH-CENTRAL MOUNTAINS
BY SUNDAY AFTERNOON AND EVENING...AND POSSIBLY A FEW RAIN/SNOW
SHOWERS TO THE NERN CORNER OF THE STATE BY EVENING. AGAIN...
NORTHWEST FACING MTN SLOPES COULD PICK UP ANOTHER FEW INCHES OF
SNOW...WITH PERHAPS AN INCH OF SNOW ON VALLEY FLOORS... AND NO
ACCUMULATION ON THE PLAINS. THIS WEATHER MAKER IS FORECAST TO
QUICKLY MOVE OUT BY MONDAY MORNING AS A STRONG HIGH PRESSURE RIDGE
BUILDS IN OVER THE GREAT BASIN. THIS RIDGE MOVES EAST ON MONDAY AND
TRAVERSES THE STATE ON TUESDAY PRODUCING PROBABLY THE WARMEST
TEMPERATURES OF THE WEEK ALONG WITH A DECENT AMOUNT OF
SUNSHINE...ESPLY EAST OF THE MTNS. BY WEDNESDAY...MEDIUM RANGE
MODELS SHOW YET ANOTHER TROUGH SWINGING ACROSS THE REGION FROM THE
CENTRAL GREAT BASIN...POTENTIALLY BRINGING MORE SNOW TO THE HIGH
COUNTRY AND POSSIBLY A FEW RAIN SHOWERS TO LOWER ELEVATIONS.
&&
.AVIATION...RAP SHOWS A CHC OF A RAIN/SNOW SHOWERS THIS AFTN WHILE
THE NAM AND GFS KEEP MOST OF THE ACTIVITY EAST OF THE AIRPORT. FOR
NOW WILL JUST MENTION VCTY IN THE TAF. WILL HAVE CONSIDERABLE MID
AND HIGH LVL CLOUDS THRU THE DAY WITH CEILINGS LOWERING TO 8000 FT
BY EARLY AFTN. THE NAM AND RAP HAVE LOWER CEILINGS DOWN TO 5000 FT
OR SO BY AFTN BUT WILL KEEP THEM AROUND 8000 FT FOR NOW. AS FOR
WINDS A SFC LOW HS FORMED EARLY THIS MORNING NR DENVER WITH LIGHT
WLY WINDS AT THE AIRPORT. THE LATEST RAP KEEPS THIS LOW NR DENVER
THRU AFTN WITH VARIABLE WIND DIRECTIONS. FOR NOW WILL HAVE THEM
TRENDING LIGHT ELY BY LATE MORNING THRU MID AFTN AND THEN BECOMING
MORE NLY BY 00Z. BY EARLY EVENING WILL HAVE NWLY WINDS FOR A FEW
HOURS AND THEN MORE WSW BY 06Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES... NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1037 PM MST THU DEC 13 2012
.AVIATION...
CLOUDS WILL BE INCREASING AND LOWERING ACRS THE AREA LATER TONIGHT
AND INTO FRI MORNING. RAP13 AND HRRR INDICATING SNOW MOVING INTO
THE KALS AREA AROUND 14Z...WITH THE POTENTIAL FOR SNOW THRU THE
DAY...BUT CHANCES DECREASING AND THEN ENDING IN THE EVENING. WITH
THE SNOW THERE SHOULD BE PERIODS OF IFR CONDITIONS. AT KPUB AND
KCOS THE FORECAST MODELS ARE MOVING PCPN INTO THE AREA AROUND 17Z-
18Z FRI AND THEN PCPN BEING POSSIBLE THRU THE DAY AND INTO THE
EVENING HOURS. CHANCES ARE THAT KPUB WILL SEE OCNL MVFR
CONDITIONS...WHILE KCOS HAS A BETTER CHANCE OF SEEING OCNL IFR
CONDITIONS IN PCPN.
&&
.PREV DISCUSSION... /ISSUED 615 PM MST THU DEC 13 2012/
SHORT TERM...
(TONIGHT AND FRIDAY)
..HEAVY SNOW FOR THE SAN JUANS TOMORROW...
CURRENTLY...AS IN PREVIOUS DAYS THIS WEEK...TEMPS SLOW TO REBOUND
FOR PUEBLO COUNTY AND THE ARKANSAS RIVER VALLEY. STILL SEEING LOWER
TO MID 40S AS OF MID DAY...WHILE FAR SERN PLAINS ARE ALREADY IN THE
60S. BKN HIGH CLOUDS CONTINUE TO MOVE OVER THE AREA IN ADVANCE OF
THE STORM SYSTEM OVER THE SRN CA COAST.
THIS STORM SYSTEM IS BOLSTERED BY A DEVELOPING SUBTROPICAL JET WHICH
WILL BE QUITE STRONG BY FRI...NR 160 KTS! EXTREME SRN PORTION OF CO
WILL BE IN FAVORABLE LEFT QUAD WITH STRONG QG LIFT AND FAVORABLE
DYNAMICS AS W-SW WINDS OF AROUND 50 KTS CRUISE JUST S OF THE 4
CORNERS. EXPECT A PERIOD OF INTENSE SNOWFALL OVER THE SAN JUANS IN
PARTICULAR...WITH SNOWFALL RATES OF UP TO 2 PER HOUR EXPECTED.
ALONG WITH STRONG WINDS...WINTER STORM WARNING FOR THE SW MTS
LOOKS ON TRACK. SNOWFALL FOR THE LOWER ELEVATIONS OF THE RIO GRANDE
DO NOT LOOK AS SPECTACULAR...BUT GIVEN THE DYNAMICS OF THE STORM
WILL MAINTAIN THE WARNING THERE AS WELL. ADVISORIES FOR THE BALANCE
OF THE MT AREAS LOOK ON TRACK...WITH 4-8 INCHES EXPECTED THERE.
MAIN QUESTION CONTINUES TO BE THE CHANCE OF SN FOR THE SAN LUIS
VALLEY AND ERN PLAINS. SRN PORTIONS OF THE VALLEY LOOK VERY FAVORABLE
FOR SOME MDT SNOW TOMORROW GIVEN THE UPPER DYNAMICS AND FAVORABLE
JET...SO HAVE BUMPED UP POPS A BIT THERE. KALS WILL BE ON THE NRN
EDGE OF EXPECTED HEAVIER SNOW...SO COULD SEE ANYTHING FROM LIGHT
ACCUMS TO POSSIBLY MODERATE ACCUMS IF STRONGER LIFT SHIFTS JUST A
BIT TO THE N. OVR THE PLAINS...NOT EXPECTING MUCH DUE TO THE
LACK OF UPSLOPE IN THE LOWER LEVELS. HOWEVER...MODELS...IN PARTICULAR
THE NAM...HAVE BEEN TRENDING TOWARDS A BIT MORE QPF OVER PORTIONS OF
THE PLAINS...AND THIS HAS BEEN PRETTY CONSISTENT FOR SEVERAL RUNS
NOW. SYSTEM LOOKS PRETTY IMPRESSIVE ON WV/IR IMAGES RIGHT NOW...AND
WOULD NOT BE SURPRISED IF DYNAMICS USURP OROGRAPHICS HERE AND GIVE
THE PLAINS A BRIEF SHOT OF SOME MDT SN TOMORROW. WILL STICK WITH
CONSERVATIVE POPS IN THE 30 PERCENT RANGE FOR NOW...BUT MAY
HAVE TO BUMP THINGS UP IF THE 00Z RUNS STILL SHOW THIS POTENTIAL.
TEMPS TOMORROW HIGHLY DEPENDENT ON PRECIP. CLOUD COVER WILL BE
PRETTY SOLID...AND WITH H7 TEMPS FALLING INTO THE MINUS 4 OR 5
RANGE...FEEL THAT MOS IS TOO HIGH...AND HAVE DROPPED HIGH TEMPS A
BIT INTO THE 40S FOR THE I-25 CORRIDOR. SHOULD BE A BIT WARMER FOR
THE ERN COUNTIES WITH A PRETTY GOOD TEMP/HUMIDITY GRADIENT SETTING
UP NR THE KS BORDER. FINALLY...LAPSE RATES LOOKING FAIRLY STEEP FRI
AFTERNOON OVER THE PLAINS...AND SPC HAS US IN THE GENERAL CONVECTIVE
OUTLOOK FOR TOMORROW. BEST CHANCE FOR TS WILL BE OVER LAS
ANIMAS...BACA...AND SRN PORTIONS OF PROWERS AND BENT COUNTIES AFTER
ABOUT 21Z. 44
LONG TERM...
(FRIDAY NIGHT THROUGH THURSDAY)
FRIDAY NIGHT THRU SATURDAY NIGHT...THE FIRST OF TWO WAVES WILL BE
EXITING THE FORECAST AREA BY 00Z SATURDAY. THE 12Z NAM/GFS/EC
BRING A CLOSED 500MB LOW THROUGH THE FAR SOUTHEAST CORNER OF
COLORADO BY 06Z...TAKING THE BULK OF THE DYNAMICS WITH IT
(INCLUDING A 120KT 300MB JET JUST TO OUR SOUTH AT THAT TIME). I
KEPT THUNDER IN THE FORECAST OVER PARTS OF KIOWA AND PROWERS
COUNTIES GIVEN THE DECENT 700-500MB LAPSE RATES (8-9C/KM). MODELS
BEGIN TO WIND DOWN QPF OVER THE CENTRAL MOUNTAINS...SAN
JUANS...AND LA GARITAS AFTER 06Z SATURDAY AND WILL LET WINTER
STORM WARNINGS AND WINTER WEATHER ADVISORIES IN THOSE AREAS EXPIRE
AT 09Z SATURDAY. MODELS SHOW A MUCH WEAKER...SECONDARY WAVE
MOVING EAST ACROSS NORTHERN NEW MEXICO LATE SATURDAY. THIS WILL
LIKELY CAUSE SOME BRIEF SNOW SHOWERS ACROSS THE SAN JUANS AND
CENTRAL MOUNTAINS...WITH ONLY ANOTHER 1 TO 3 INCHES POSSIBLE LATE
SATURDAY AFTERNOON AND EVENING.
SUNDAY...THE 12Z NAM AND GFS SHOW NORTHWEST FLOW OVER THE REGION
SUNDAY WITH SOME WEAK SHORTWAVES IN THE FLOW PASSING OVER THE
REGION. THIS WILL FAVOR SOME SNOW SHOWERS ACROSS THE CENTRAL
MOUNTAINS SUNDAY AFTERNOON AND EVENING WITH MINIMAL ACCUMULATIONS
EXPECTED.
MONDAY THROUGH TUESDAY NIGHT...THE FORECAST AREA WILL BE BETWEEN
SYSTEMS DURING THIS TIME. THE REGION WILL BE UNDER NORTHWEST FLOW
THROUGH EARLY TUESDAY...AND BEGIN TO TURN MORE WEST AND
SOUTHWESTERLY AS WEAK RIDGING SLOWLY BUILDS OVER THE REGION
TUESDAY AHEAD OF AN APPROACHING SYSTEM. 700MB TEMPERATURES WILL
WARM TO +3 TO +6 ACROSS THE I-25 CORRIDOR AND EASTERN PLAINS
TUESDAY AFTERNOON WHICH WILL LEAD TO HIGH TEMPERATURES IN THE
LOWER 50S IN THOSE AREAS. THE GFS AND EC MOVE THE RIDGE AXIS
ACROSS EASTERN COLORADO BY 00Z TUESDAY.
WEDNESDAY AND THURSDAY...THE GFS AND EC ARE IN DECENT AGREEMENT
ON A SHORTWAVE PASSING TO THE NORTH OF THE FORECAST AREA WEDNESDAY
AFTERNOON WITH A COLD FRONTAL PASSAGE ACROSS THE PLAINS BY 00Z
THURSDAY. THIS LOOKS TO BE A FAIRLY FAST MOVING SYSTEM WITH THE
BULK OF THE MOISTURE BEING CONFINED TO THE SAN JUANS AND CENTRAL
MOUNTAINS. 30 TO 40 POPS IN THOSE REGIONS SEEMED REASONABLE GIVEN
MODEL AGREEMENT AT THIS TIME. RIDGING WILL QUICKLY BUILD IN BEHIND
THIS SYSTEM BRINGING WEST AND SOUTHWESTERLY FLOW WITH DRY
CONDITIONS TO ALL OF THE FORECAST AREA. -PJC
AVIATION...
MAIN CONCERN CONTINUES TO BE ANTICIPATED IFR CONDITIONS AT KALS
FRI MORNING...GENERALLY FROM 12-18Z PERIOD...AS WELL AS LESSER
POTENTIAL FOR MVFR-IFR AT KCOS FOR THE SAME TIME PERIOD. CHANCES
FOR PRECIP REMAIN IN THE 50-60 PERCENT RANGE FOR KALS...AND 20-30
PERCENT FOR KPUB AND KCOS. RESTRICTIONS TO VIS/LOW CIGS MORE LIKELY
AT KCOS SO WILL CONTINUE EXPLICIT MENTION IN TAFS THERE...WITH VCSH
AT KPUB. HEAVY SNOW EXPECTED FOR THE SW MTS TOMORROW...AND LIGHT
TO MDT ACCUMS FOR THE OTHER MT RANGES. COULD ALSO SEE SOME ISOLD
TS FOR THE FAR SERN PLAINS...NR OK/CO AND CO/KS BORDERS AFTER
NOON TOMORROW. 44
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 2 AM FRIDAY TO 2 AM MST SATURDAY
FOR COZ060-064-073-075.
WINTER STORM WARNING FROM 2 AM FRIDAY TO 2 AM MST SATURDAY FOR
COZ066>068.
&&
$$
AREA FORECAST DISCUSSION
NWS MIAMI FL
858 PM EST SAT DEC 15 2012
.UPDATE...
ALTHOUGH LATEST MIAMI SOUNDING SHOWS SLIGHTLY DRIER AIR IN THE
LOWER LEVELS, STUBBORN PATCH OF CLOUDS/SHOWERS STILL AFFECTING
PARTS OF SOUTH FLORIDA, ESPECIALLY ACROSS NORTHERN MIAMI-DADE
COUNTY. RAISED POPS FOR THE FIRST HALF OF THE NIGHT TO 20/30
PERCENT SOUTH OF ALLIGATOR ALLEY TO ACCOUNT FOR CURRENT TRENDS,
WITH LOWER POPS OVERNIGHT AS BACK EDGE OF MOISTURE SHOULD START TO
MOVE IN. ADDITIONAL CLOUDS WITH LIKELY A FEW SHOWERS DOWNWIND OVER
THE NORTHERN BAHAMAS MAY HOLD TOGETHER ENOUGH TO KEEP AN ISOLATED
SHOWER MENTION EAST COAST ALL NIGHT, BUT FOR NOW WILL REMAIN
OPTIMISTIC AND KEEP OUT OF ZONE FORECAST.
ALSO KEPT PATCHY FOG FOR INLAND AREAS OVERNIGHT AS HIGH SURFACE
MOISTURE WITH DEWPOINTS IN LOWER/MID 60S AND LIGHTER WINDS
SHOULD PROMOTE FOG DEVELOPMENT. ALL OTHER FORECAST ELEMENTS LOOK
GOOD. /MOLLEDA
&&
.PREV DISCUSSION... /ISSUED 630 PM EST SAT DEC 15 2012/
AVIATION...
MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THE END OF THE TAF
PERIOD. SHOWERS ARE BEGINNING TO REDEVELOP OVER THE ATLANTIC
WATERS AND MOVING IN THE GENERAL DIRECTION OF KOPF AND KMIA. SO
WILL KEEP VCSH IN FOR THOSE TAF SITES FOR THE NEXT SEVERAL HOURS.
MVFR CONDITIONS WILL BE POSSIBLE IF A SHOWER GOES OVER ONE OF THE
TAF SITES. LIGHT EAST NORTHEAST OR EAST WINDS ARE EXPECTED
OVERNIGHT. WINDS WILL VEER TO THE SOUTHEAST DURING THE DAY ON
SUNDAY AND INCREASE TO AROUND 10 KNOTS. THERE WILL STILL BE A
CHANCE FOR LIGHT SHOWERS NEAR THE SOUTHERN HALF OF THE EAST COAST
TAF SITES ON SUNDAY...BUT LEFT OUT OF THE TAF SITES FOR NOW.
PREV DISCUSSION... /ISSUED 238 PM EST SAT DEC 15 2012/
DISCUSSION...
SCATTERED SHOWERS CONTINUE TO STREAM INTO SOUTH FLORIDA UNDER A
CONTINUED MID LEVEL INVERSION AND EAST-NORTHEASTERLY SURFACE FLOW.
LATEST HRRR DEPICTS SHOWERS DIMINISHING IN COVERAGE THROUGH THE
EVENING AND OVERNIGHT HOURS AS UPPER RIDGING BEGINS TO BUILD
ACROSS THE AREA FROM THE GULF OF MEXICO. AS RIDGING BUILDS
IN...WINDS WILL BEGIN TO DIMINISH ACROSS THE ATLANTIC WATERS
REDUCING THE RIP CURRENT THREAT SLIGHTLY INTO SUNDAY. WITH LIGHTER
WINDS OVERNIGHT AND CONTINUED LOW LEVEL MOISTURE...PLACED PATCHY
FOG ACROSS INTERIOR AREAS THROUGH THE OVERNIGHT AND EARLY MORNING
HOURS.
SUNDAY INTO MONDAY LOOK MAINLY DRY AS UPPER RIDGING DOMINATES THE
SOUTH FLORIDA PENINSULA. SURFACE WINDS WILL BECOME MORE
SOUTHEASTERLY AS A COLD FRONT APPROACHES FROM THE NORTH. BY MONDAY
NIGHT RIDGING WILL BEGIN TO BREAK DOWN AS THE FRONT PUSHES INTO
CENTRAL FLORIDA. SHOWERS AND POSSIBLE THUNDERSTORMS ARE EXPECTED
TO DEVELOP AND PUSH ACROSS SOUTH FLORIDA AS THE FRONT PASSES
THROUGH TUESDAY AFTERNOON. MODELS SEEM TO HAVE A GOOD HANDLE ON
THE TIMING OF THIS SYSTEM.
BY WEDNESDAY RIDGING RETURNS IN THE WAKE OF THE FRONT. WEDNESDAY
MORNING COULD SEE LOWS IN THE 40S ACROSS INTERIOR AREAS WITH MID
TO UPPER 50S ELSEWHERE. THE OVERALL PATTERN FOR THE LATTER HALF OF
NEXT WEEK SEEMS TO BE MUCH MORE PROGRESSIVE. SOUTHERLY FLOW
QUICKLY RETURNS OVERNIGHT WEDNESDAY INTO THURSDAY AS ANOTHER FRONT
APPROACHES THE NORTHERN GULF OF MEXICO. RAIN CHANCES RETURN FRIDAY
AS THE FRONT PUSHES INTO SOUTH FLORIDA.
MARINE...
EAST-NORTHEASTERLY WINDS ARE SLOWLY BECOMING MORE EASTERLY AND ARE
BEGINNING TO WEAKEN SLIGHTLY ACROSS THE ATLANTIC WATERS. SHOULD
STILL SEE SEAS IN THE 5 TO 6 FOOT RANGE ACROSS MAINLY THE NEAR AND
OFFSHORE WATERS OF PALM BEACH COUNTY. DECIDED TO KEEP MENTION OF
SMALL CRAFT SHOULD EXERCISE CAUTION FOR THIS AREA. ALSO EXTENDED THE
HIGH RISK OF RIP CURRENTS ACROSS THE BEACHES OF PALM BEACH COUNTY.
FIRE WEATHER...
STILL NO FIRE WEATHER CONCERNS AT THIS TIME. LOW LEVEL MOISTURE
WILL REMAIN WELL ABOVE CRITICAL THRESHOLDS ACROSS THE ENTIRE AREA
THROUGH THE PERIOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH MMM 80 68 80 / 10 10 - 10
FORT LAUDERDALE MMM 80 71 81 / 20 10 - 10
MIAMI MMM 81 71 81 / 30 10 - 10
NAPLES MMM 81 66 80 / 20 10 - 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...59/RM
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS MIAMI FL
630 PM EST SAT DEC 15 2012
.AVIATION...
MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THE END OF THE TAF
PERIOD. SHOWERS ARE BEGINNING TO REDEVELOP OVER THE ATLANTIC
WATERS AND MOVING IN THE GENERAL DIRECTION OF KOPF AND KMIA. SO
WILL KEEP VCSH IN FOR THOSE TAF SITES FOR THE NEXT SEVERAL HOURS.
MVFR CONDITIONS WILL BE POSSIBLE IF A SHOWER GOES OVER ONE OF THE
TAF SITES. LIGHT EAST NORTHEAST OR EAST WINDS ARE EXPECTED
OVERNIGHT. WINDS WILL VEER TO THE SOUTHEAST DURING THE DAY ON
SUNDAY AND INCREASE TO AROUND 10 KNOTS. THERE WILL STILL BE A
CHANCE FOR LIGHT SHOWERS NEAR THE SOUTHERN HALF OF THE EAST COAST
TAF SITES ON SUNDAY...BUT LEFT OUT OF THE TAF SITES FOR NOW.
&&
.PREV DISCUSSION... /ISSUED 238 PM EST SAT DEC 15 2012/
DISCUSSION...
SCATTERED SHOWERS CONTINUE TO STREAM INTO SOUTH FLORIDA UNDER A
CONTINUED MID LEVEL INVERSION AND EAST-NORTHEASTERLY SURFACE FLOW.
LATEST HRRR DEPICTS SHOWERS DIMINISHING IN COVERAGE THROUGH THE
EVENING AND OVERNIGHT HOURS AS UPPER RIDGING BEGINS TO BUILD
ACROSS THE AREA FROM THE GULF OF MEXICO. AS RIDGING BUILDS
IN...WINDS WILL BEGIN TO DIMINISH ACROSS THE ATLANTIC WATERS
REDUCING THE RIP CURRENT THREAT SLIGHTLY INTO SUNDAY. WITH LIGHTER
WINDS OVERNIGHT AND CONTINUED LOW LEVEL MOISTURE...PLACED PATCHY
FOG ACROSS INTERIOR AREAS THROUGH THE OVERNIGHT AND EARLY MORNING
HOURS.
SUNDAY INTO MONDAY LOOK MAINLY DRY AS UPPER RIDGING DOMINATES THE
SOUTH FLORIDA PENINSULA. SURFACE WINDS WILL BECOME MORE
SOUTHEASTERLY AS A COLD FRONT APPROACHES FROM THE NORTH. BY MONDAY
NIGHT RIDGING WILL BEGIN TO BREAK DOWN AS THE FRONT PUSHES INTO
CENTRAL FLORIDA. SHOWERS AND POSSIBLE THUNDERSTORMS ARE EXPECTED
TO DEVELOP AND PUSH ACROSS SOUTH FLORIDA AS THE FRONT PASSES
THROUGH TUESDAY AFTERNOON. MODELS SEEM TO HAVE A GOOD HANDLE ON
THE TIMING OF THIS SYSTEM.
BY WEDNESDAY RIDGING RETURNS IN THE WAKE OF THE FRONT. WEDNESDAY
MORNING COULD SEE LOWS IN THE 40S ACROSS INTERIOR AREAS WITH MID
TO UPPER 50S ELSEWHERE. THE OVERALL PATTERN FOR THE LATTER HALF OF
NEXT WEEK SEEMS TO BE MUCH MORE PROGRESSIVE. SOUTHERLY FLOW
QUICKLY RETURNS OVERNIGHT WEDNESDAY INTO THURSDAY AS ANOTHER FRONT
APPROACHES THE NORTHERN GULF OF MEXICO. RAIN CHANCES RETURN FRIDAY
AS THE FRONT PUSHES INTO SOUTH FLORIDA.
MARINE...
EAST-NORTHEASTERLY WINDS ARE SLOWLY BECOMING MORE EASTERLY AND ARE
BEGINNING TO WEAKEN SLIGHTLY ACROSS THE ATLANTIC WATERS. SHOULD
STILL SEE SEAS IN THE 5 TO 6 FOOT RANGE ACROSS MAINLY THE NEAR AND
OFFSHORE WATERS OF PALM BEACH COUNTY. DECIDED TO KEEP MENTION OF
SMALL CRAFT SHOULD EXERCISE CAUTION FOR THIS AREA. ALSO EXTENDED THE
HIGH RISK OF RIP CURRENTS ACROSS THE BEACHES OF PALM BEACH COUNTY.
FIRE WEATHER...
STILL NO FIRE WEATHER CONCERNS AT THIS TIME. LOW LEVEL MOISTURE
WILL REMAIN WELL ABOVE CRITICAL THRESHOLDS ACROSS THE ENTIRE AREA
THROUGH THE PERIOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 67 80 68 80 / 10 10 - 10
FORT LAUDERDALE 69 80 71 81 / 10 10 - 10
MIAMI 68 81 71 81 / 10 10 - 10
NAPLES 63 81 66 80 / 10 10 - 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...HIGH RIP CURRENT RISK UNTIL 7 PM EST THIS EVENING FOR COASTAL
PALM BEACH.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...59/RM
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS LINCOLN IL
850 PM CST SAT DEC 15 2012
.DISCUSSION...
ISSUED 850 PM CST SAT DEC 15 2012
UPDATED THE GRIDDED FORECAST AND WILL BE UPDATING THE ZONES SOON
TO REFLECT THE LATEST TEMPERATURE...SKY COVER AND WEATHER CONDITIONS.
AN OCCLUDED FRONT EXTENDED FROM A LOW IN SOUTHEAST MN INTO WEST
CENTRAL IL AND TOWARD STL. THE RADAR INDICATED VERY LIGHT SHOWERS
AND SPRINKLES SCATTERED ALONG THE I-74 CORRIDOR FROM SOUTHEAST OF
GBG TO DNV. WILL KEEP A MENTION OF SCATTERED SPRINKLES IN THE
FORECAST OVERNIGHT FOR THESE LOCATIONS SINCE THE FRONT WILL MOVE
VERY SLOWLY OVERNIGHT AND LOW LEVEL WSW WINDS ON THE ILX 00Z
SOUNDING INDICATE THAT WEAK OVERRUNNING WILL CONTINUE. THE HRRR
MODEL FROM 00Z IS ACTUALLY DOING A GOOD JOB OF DEPICTING THIS
LIGHT RAINFALL IN THESE SAME AREAS.
BUMPED UP LOW TEMPERATURES OVERNIGHT FOR THE SAME REASONS STATED
ABOVE...RELATED TO THE SLOW MOVING OCCLUDED FRONT AND ANTICIPATED
CLOUD COVER. THE LATEST IR SATELLITE LOOP IS SHOWING SOME CLEARING
AROUND TAYLORVILLE AND SOUTH OF I-70. HOWEVER...THIS WILL MOST
LIKELY BE SHORT LIVED...SO TEMPERATURES WILL REMAIN QUITE MILD FOR
A MID-DECEMBER NIGHT.
MILLER
&&
.AVIATION...
ISSUED 555 PM CST SAT DEC 15 2012
A SURFACE LOW IN NORTH CENTRAL IOWA AND ITS ASSOCIATED UPPER LEVEL
CIRCULATION IN EASTERN WI CONTINUE TO SLOWLY LIFT TO THE
NORTHEAST. THE DRY SLOT WITH THE UPPER LEVEL SYSTEM HAS SPREAD
INTO CENTRAL IL WHICH HAS ALLOWED CIGS TO CLIMB TO VFR LEVELS THE
PAST FEW HOURS. THE MAIN CONCERN FOR THE TAFS OVERNIGHT WILL BE
THE NORTHERN AND EASTERN EXTENT OF THE LOW LEVEL DRY AIR...AND ITS
INFLUENCE ON CIGS AND VSBYS TONIGHT INTO SUNDAY MORNING.
THE LATEST IR SATELLITE LOOP INDICATED THAT THE DRIER LOW LEVEL
AIR WITH SCT-BKN VFR CLOUD BASES WILL CONTINUE TO SHIFT TO THE
EAST-NORTHEAST THE NEXT FEW HOURS. SHOULD SEE SOME PARTIAL
CLEARING FROM KSPI-KDEC-KCMI BEFORE 0200 TO 0400 UTC. HOWEVER...DUE
TO VERY MOIST CONDITIONS RIGHT AT THE SURFACE WOULD EXPECT MVFR
CIGS TO FORM SHORTLY AFTER THE PARTIAL CLEARING. SREF AND NAM
FORECAST SOUNDINGS AND HRRR MODEL CIG FORECASTS POINT TO THE
LIKELIHOOD OF THIS OCCURRENCE. WILL NEED TO KEEP AN EYE ON THE
TIMING...AS THERE IS LOW CONFIDENCE AS TO HOW QUICKLY THIS MAY
OCCUR.
AM EXPECTING CIGS AND VSBY TO LOWER TO MVFR CONDITIONS AT THE
NORTHERN TAF SITES OF KPIA AND KBMI AS WELL...BUT NOT UNTIL THE
0600 TO 1000 UTC TIMEFRAME. THE FORECAST SOUNDINGS ALSO POINT TO
MOISTURE TRAPPED IN THE LOW LEVELS THROUGH SUNDAY MORNING AND INTO
MUCH OF THE AFTERNOON. THIS WILL KEEP MVFR CONDITIONS IN PLACE
UNTIL THE LEADING EDGE OF THE COOLER AND DRIER AIR ADVANCES INTO
THE REGION LATE IN THE AFTERNOON.
MILLER
&&
.PREV DISCUSSION...
ISSUED 300 PM CST SAT DEC 15 2012
A WEAKENING AREA OF LOW PRESSURE CENTERED OVER NORTHERN IOWA WILL
CONTINUE TO LIFT NORTHEAST OVER THE NEXT COUPLE DAYS AS IT
GRADUALLY DISSIPATES. IN THE WAKE OF THIS SYSTEM...MOSTLY QUIET
WEATHER IS ANTICIPATED UNTIL A POTENTIALLY MAJOR STORM SYSTEM
IMPACTS THE AREA LATE NEXT WEEK. THIS LATE WEEK SYSTEM IS THE
PRIMARY FORECAST CONCERN TODAY.
12Z MODELS IN REASONABLE AGREEMENT IN THE NEXT FEW DAYS...ALTHOUGH
THEY CONTINUE TO DISAGREE WITH THE RISK OF PRECIPITATION FOR
MONDAY/TUESDAY AS A DISTURBANCE CURRENTLY COMING ASHORE ALONG THE
PACIFIC NORTHWEST MOVES THROUGH THE AREA. FEEL A DRIER FORECAST IS
THE WAY TO GO WITH THIS FEATURE DUE TO THE LACK OF MOISTURE RETURN
POSSIBLE BEHIND THIS CURRENT SYSTEM AND ONLY MODEST FORCING WITH
THE LOW AMPLITUDE WAVE. WITH THE LATE WEEK SYSTEM...MAINLY
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...FEEL A BLEND OF SOLUTIONS
IS STILL THE WAY TO GO CONSIDERING THE PERSISTENT MODEL/ENSEMBLE
SPREAD AND RUN-TO-RUN VARIABILITY. HOWEVER...THE PAST COUPLE OF
RUNS HAS SEEN MOST OF THE OPERATIONAL MODELS MORE CONSISTENT WITH
THEMSELVES DESPITE A CONSENSUS NOT BEING REACHED.
SHORT TERM...TONIGHT THROUGH TUESDAY...STILL SOME LIGHT RAIN
POSSIBLE IN THE WRAP AROUND MOISTURE WITH THE CURRENT SYSTEM...BUT
IT SHOULD BE MINIMAL IF IT OCCURS. THE COLD AIR/FRONT WITH THIS
SYSTEM DOES NOT REALLY SURGE INTO THE AREA UNTIL LATE SUNDAY...SO
ONE MORE MILD DAY IS ANTICIPATED.
THE UPPER LEVEL FLOW TRENDS MORE ZONAL FOR THE MOST PART IN THE
WAKE OF TODAY/S SYSTEM...ALTHOUGH THE PAC NW WAVE OR PIECES OF IT
WILL RIPPLE THROUGH THE AREA DURING THE MONDAY/TUESDAY TIME FRAME.
HAVE MAINTAINED SLIGHT CHANCE POPS MONDAY/MONDAY NIGHT IN ADVANCE
OF THE MAIN ENERGY...BUT MOISTURE IS TOO LACKING TO GO WITH MUCH
MORE THAN THAT. TEMPERATURES WILL BE A LITTLE COOLER THAN OVER THE
WEEKEND...BUT STILL WARMER THAN NORMAL.
LONG TERM...WEDNESDAY THROUGH SATURDAY...A MAJOR STORM APPEARS
POISED TO IMPACT THE AREA WEDNESDAY NIGHT INTO THURSDAY NIGHT.
SHOWER/STORMS ARE LIKELY IN THE WARM SECTOR TO THE EAST OF THE
STORM TRACK...WITH SNOW LIKELY IN THE COLD AIR TO THE WEST. THE
LATEST GFS STILL KEEPS FORECAST AREA IN THE WARM SECTOR DURING
MOST OF THE TIME PRECIPITATION IS EXPECTED...WHILE THE ECMWF HAS SNOW
POSSIBLE OVER AT LEAST THE WESTERN HALF OF THE FORECAST AREA. THE
ECMWF ALSO WOULD SUPPORT MUCH COLDER CONDITIONS IN THE WAKE OF THE
SYSTEM...WHILE THE GFS IF MORE MODERATE. AS STATED ABOVE...PLAYING
A MIDDLE OF THE ROAD SOLUTION FOR NOW GIVEN MODEL/ENSEMBLE
SPREAD...BUT THE MODEL TRENDS WITH THIS SYSTEM WILL NEED TO BE
MONITORED CLOSELY.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
556 PM CST SAT DEC 15 2012
.DISCUSSION...
ISSUED 300 PM CST SAT DEC 15 2012
A WEAKENING AREA OF LOW PRESSURE CENTERED OVER NORTHERN IOWA WILL
CONTINUE TO LIFT NORTHEAST OVER THE NEXT COUPLE DAYS AS IT
GRADUALLY DISSIPATES. IN THE WAKE OF THIS SYSTEM...MOSTLY QUIET
WEATHER IS ANTICIPATED UNTIL A POTENTIALLY MAJOR STORM SYSTEM
IMPACTS THE AREA LATE NEXT WEEK. THIS LATE WEEK SYSTEM IS THE
PRIMARY FORECAST CONCERN TODAY.
12Z MODELS IN REASONABLE AGREEMENT IN THE NEXT FEW DAYS...ALTHOUGH
THEY CONTINUE TO DISAGREE WITH THE RISK OF PRECIPITATION FOR
MONDAY/TUESDAY AS A DISTURBANCE CURRENTLY COMING ASHORE ALONG THE
PACIFIC NORTHWEST MOVES THROUGH THE AREA. FEEL A DRIER FORECAST IS
THE WAY TO GO WITH THIS FEATURE DUE TO THE LACK OF MOISTURE RETURN
POSSIBLE BEHIND THIS CURRENT SYSTEM AND ONLY MODEST FORCING WITH
THE LOW AMPLITUDE WAVE. WITH THE LATE WEEK SYSTEM...MAINLY
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...FEEL A BLEND OF SOLUTIONS
IS STILL THE WAY TO GO CONSIDERING THE PERSISTENT MODEL/ENSEMBLE
SPREAD AND RUN-TO-RUN VARIABILITY. HOWEVER...THE PAST COUPLE OF
RUNS HAS SEEN MOST OF THE OPERATIONAL MODELS MORE CONSISTENT WITH
THEMSELVES DESPITE A CONSENSUS NOT BEING REACHED.
SHORT TERM...TONIGHT THROUGH TUESDAY...STILL SOME LIGHT RAIN
POSSIBLE IN THE WRAP AROUND MOISTURE WITH THE CURRENT SYSTEM...BUT
IT SHOULD BE MINIMAL IF IT OCCURS. THE COLD AIR/FRONT WITH THIS
SYSTEM DOES NOT REALLY SURGE INTO THE AREA UNTIL LATE SUNDAY...SO
ONE MORE MILD DAY IS ANTICIPATED.
THE UPPER LEVEL FLOW TRENDS MORE ZONAL FOR THE MOST PART IN THE
WAKE OF TODAY/S SYSTEM...ALTHOUGH THE PAC NW WAVE OR PIECES OF IT
WILL RIPPLE THROUGH THE AREA DURING THE MONDAY/TUESDAY TIME FRAME.
HAVE MAINTAINED SLIGHT CHANCE POPS MONDAY/MONDAY NIGHT IN ADVANCE
OF THE MAIN ENERGY...BUT MOISTURE IS TOO LACKING TO GO WITH MUCH
MORE THAN THAT. TEMPERATURES WILL BE A LITTLE COOLER THAN OVER THE
WEEKEND...BUT STILL WARMER THAN NORMAL.
LONG TERM...WEDNESDAY THROUGH SATURDAY...A MAJOR STORM APPEARS
POISED TO IMPACT THE AREA WEDNESDAY NIGHT INTO THURSDAY NIGHT.
SHOWER/STORMS ARE LIKELY IN THE WARM SECTOR TO THE EAST OF THE
STORM TRACK...WITH SNOW LIKELY IN THE COLD AIR TO THE WEST. THE
LATEST GFS STILL KEEPS FORECAST AREA IN THE WARM SECTOR DURING
MOST OF THE TIME PRECIPITATION IS EXPECTED...WHILE THE ECMWF HAS SNOW
POSSIBLE OVER AT LEAST THE WESTERN HALF OF THE FORECAST AREA. THE
ECMWF ALSO WOULD SUPPORT MUCH COLDER CONDITIONS IN THE WAKE OF THE
SYSTEM...WHILE THE GFS IF MORE MODERATE. AS STATED ABOVE...PLAYING
A MIDDLE OF THE ROAD SOLUTION FOR NOW GIVEN MODEL/ENSEMBLE
SPREAD...BUT THE MODEL TRENDS WITH THIS SYSTEM WILL NEED TO BE
MONITORED CLOSELY.
&&
.AVIATION...
ISSUED 555 PM CST SAT DEC 15 2012
A SURFACE LOW IN NORTH CENTRAL IOWA AND ITS ASSOCIATED UPPER LEVEL
CIRCULATION IN EASTERN WI CONTINUE TO SLOWLY LIFT TO THE
NORTHEAST. THE DRY SLOT WITH THE UPPER LEVEL SYSTEM HAS SPREAD
INTO CENTRAL IL WHICH HAS ALLOWED CIGS TO CLIMB TO VFR LEVELS THE
PAST FEW HOURS. THE MAIN CONCERN FOR THE TAFS OVERNIGHT WILL BE
THE NORTHERN AND EASTERN EXTENT OF THE LOW LEVEL DRY AIR...AND ITS
INFLUENCE ON CIGS AND VSBYS TONIGHT INTO SUNDAY MORNING.
THE LATEST IR SATELLITE LOOP INDICATED THAT THE DRIER LOW LEVEL
AIR WITH SCT-BKN VFR CLOUD BASES WILL CONTINUE TO SHIFT TO THE
EAST-NORTHEAST THE NEXT FEW HOURS. SHOULD SEE SOME PARTIAL
CLEARING FROM KSPI-KDEC-KCMI BEFORE 0200 TO 0400 UTC. HOWEVER...DUE
TO VERY MOIST CONDITIONS RIGHT AT THE SURFACE WOULD EXPECT MVFR
CIGS TO FORM SHORTLY AFTER THE PARTIAL CLEARING. SREF AND NAM
FORECAST SOUNDINGS AND HRRR MODEL CIG FORECASTS POINT TO THE
LIKELIHOOD OF THIS OCCURRENCE. WILL NEED TO KEEP AN EYE ON THE
TIMING...AS THERE IS LOW CONFIDENCE AS TO HOW QUICKLY THIS MAY
OCCUR.
AM EXPECTING CIGS AND VSBY TO LOWER TO MVFR CONDITIONS AT THE
NORTHERN TAF SITES OF KPIA AND KBMI AS WELL...BUT NOT UNTIL THE
0600 TO 1000 UTC TIMEFRAME. THE FORECAST SOUNDINGS ALSO POINT TO
MOISTURE TRAPPED IN THE LOW LEVELS THROUGH SUNDAY MORNING AND INTO
MUCH OF THE AFTERNOON. THIS WILL KEEP MVFR CONDITIONS IN PLACE
UNTIL THE LEADING EDGE OF THE COOLER AND DRIER AIR ADVANCES INTO
THE REGION LATE IN THE AFTERNOON.
MILLER
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
300 PM CST FRI DEC 14 2012
.SHORT TERM /TONIGHT/...
FAIRLY STRAIGHTFORWARD FORECAST WITH THE UPCOMING SYSTEM THAT WILL
IMPACT THE REGION TONIGHT. SHARP NEGATIVELY TILTED 300 MB SHORTWAVE
OVER THE FOUR CORNERS REGION HAS BEGUN EJECTING NORTHEASTWARD AND
ACCELERATING TOWARDS THE UPPER MIDWEST THIS AFTERNOON. OVER THE LAST
24 HOURS...THIS WAVE...WHICH ORIGINATED IN THE POLAR JET...HAS
PHASED WITH THE SUBTROPICAL JET OVER THE BAJA PENINSULA AND HELPED
PULL PACIFIC MOISTURE NORTHEASTWARD INTO THE UPPER MIDWEST. THIS IS
WELL DEPICTED ON CURRENT WATER VAPOR SATELLITE IMAGERY. CIRROSTRATUS
ASSOCIATED WITH THIS MOISTURE PLUME HAS ALREADY REACHED CENTRAL
IOWA...BUT DID LITTLE TO STOP TEMPERATURES FROM SOARING WELL ABOVE
NORMAL INTO THE LOW TO MID 50S ACROSS THE CWA.
AN ADDITIONAL SHORTWAVE DROPPING SOUTH ALONG THE US WEST COAST WILL
AID IN USHERING THE AFOREMENTIONED SYSTEM INTO THE UPPER MIDWEST
TONIGHT. LEE CYCLOGENESIS ALONG THE FRONT RANGE WILL RESULT IN A
998MB SURFACE CYCLONE DEVELOPING BY 00Z IN EASTERN COLORADO THAT
WILL PROGRESS EAST NORTHEASTWARD INTO EASTERN NEBRASKA BY 12Z
SATURDAY MORNING. SIGNIFICANT MOISTURE ADVECTION FROM THE WESTERN
GULF WILL RESULT IN +2 STANDARD DEVIATION PWATS OF 0.75 INCHES TO
NEARLY AN INCH OVER IOWA (COMPARED TO THE DVN RAOB SITE) BY 06Z
TONIGHT. THIS LOW LEVEL GULF MOISTURE...COMBINED WITH THE UPPER
LEVEL MOISTURE FROM THE PACIFIC...WILL PRIME THE ATMOSPHERIC COLUMN
FOR A SIGNIFICANT RAINFALL EVENT. EXTENSIVE MID TO UPPER LEVEL
FORCING ASSOCIATED WITH THE UPPER LEVEL SYSTEM WILL BE THE MAIN
DRIVER FOR PRECIPITATION OVERNIGHT. THIS IS DEPICTED WELL IN THE
STRONG Q-VECTOR CONVERGENCE FIELDS FROM 500-300MB AND THE RESULTANT
OMEGA CROSS SECTIONS WHICH SHOW DEEP AND WIDESPREAD LIFT FROM 700 TO
300 MB OVER CENTRAL IOWA BETWEEN 06 AND 12Z.
MID TO LOW LEVEL FRONTOGENESIS IS ALSO PRESENT FROM 700 TO 800 MB
DURING THIS TIME AND MAY LEAD TO SOME LOCALIZED BANDS OF ENHANCED
RAINFALL. GIVEN THE FAST PROGRESSION OF THE SYSTEM...HAVE OPTED TO
MAKE MINIMAL CHANGES TO THE STORM TOTAL QPF FORECAST OF 0.60 TO 0.70
INCHES OF RAIN FOR THE CWA. THE INGREDIENTS ARE ALL IN PLACE...BUT
ONLY FOR A SHORT PERIOD. SOME ELEVATED CONVECTIVE INSTABILITY
RESULTING FROM STEEPING MID-LEVEL LAPSE RATES COULD BE ENOUGH TO
GENERATE A FEW THUNDERSTORMS OVER SOUTHERN IOWA...SO CONTINUED
ISOLATED THUNDER WORDING IN THE GRIDS SOUTH OF I-80.
TEMPERATURES ALSO PROVED TO BE A BIT OF A CHALLENGE DUE TO THE WARM
FRONT THAT WAS OVER CENTRAL IOWA OVERNIGHT LIFTING FURTHER NORTH
THAN PREVIOUSLY ANTICIPATED...RESULTING IN WARMER READINGS ACROSS
THE NORTHERN CWA. THE RUC AND NAM DNG DID A GOOD JOB THIS MORNING
DEPICTING THE FASTER WARM FRONT PROGRESSION AND WARMER
TEMPERATURES...SO LEANED TOWARDS THESE TWO MODELS WITH OVERNIGHT
LOWS. THIS RESULTED IN LITTLE CHANGE TO THE SOUTHERN HALF OF THE CWA
BUT RAISED TEMPERATURES 2 TO 3 DEGREES IN THE NORTH. WENT WITH A
NON-DIURNAL COOLING TREND FOR OVERNIGHT TEMPERATURES GIVEN THE
WIDESPREAD CLOUDS..RAIN...AND CONTINUED SOUTHERLY WARM AIR ADVECTION.
.LONG TERM /SATURDAY THROUGH FRIDAY/...
FAIRLY ACTIVE WEATHER PATTERN FOR THE NEXT WEEK ACROSS THE CENTRAL
UNITED STATES. LOOKS LIKE TWO WEATHER SYSTEMS MAY PRODUCE
PRECIPITATION OVER CENTRAL IOWA. THE FIRST SYSTEM...TONIGHT AND
SATURDAY...WILL CERTAINLY PRODUCE WIDESPREAD RAIN. THE SECOND
SYSTEM MAY PRODUCE MORE WINTERLIKE WEATHER.
IN THE BIG PICTURE...SHORT RANGE MODELS ARE IN GOOD AGREEMENT
EJECTING AN UPPER LOW ACROSS THE STATE SATURDAY. EXTENSIVE BAND OF
RAIN SHOULD MOVE THROUGH NORTHERN IOWA SATURDAY MORNING IN RESPONSE
TO IMPRESSIVE UPPER LEVEL DYNAMICS AND MOISTURE ADVECTION. THE RAIN
BAND SHOULD EXIT THE FORECAST AREA DURING THE MORNING WHILE THE
SURFACE LOW MOVES OVER THE STATE. DON/T EXPECT MUCH RAINFALL AFTER
THE INITIAL PRECIPITATION BAND MOVES THROUGH...BUT THERE WILL BE
SOME RESIDUAL LIGHT RAIN LEFT BEHIND ON SATURDAY. SECONDARY PIECE OF
SHORTWAVE ENERGY MOVES THROUGH SATURDAY PROVIDING A PERIOD OF BRIEF
FORCING. HOWEVER...GIVEN THE SPEED OF THIS FEATURE...DO NOT EXPECT
MUCH SENSIBLE WEATHER.
FROM SUNDAY THROUGH TUESDAY...A BROAD UPPER TROUGH ESTABLISHES
ITSELF OVER THE CENTRAL CONUS ON SUNDAY. THE TROUGH APPEARS TO BE
PROGRESSIVE WHICH SEEMS REASONABLE GIVEN THE RECENT PATTERN. THE
NEXT SIGNIFICANT UPPER TROUGH IN FLOW IS FORECAST TO IMPACT THE
CENTRAL US MIDWEEK. THE 12Z ECMWF IS SLOWER AND MORE AMPLIFIED WITH
THIS TROUGH AND DEVELOPS A 500 MB LOW OVER THE AREA BY THURSDAY
MORNING. IN TURN...IT QUICKLY DEEPENS A SURFACE AND TRACKS IT
THROUGH MISSOURI AND INTO ILLINOIS. THIS IS A FAVORABLE TRACK FOR A
SNOW EVENT IN CENTRAL IOWA AND THIS SYSTEM WILL NEED TO BE
MONITORED. HOWEVER...THE GFS KEEPS THE WAVE OPEN AND MORE
PROGRESSIVE THUS LESS PRECIPITATION. IT DOES PRODUCE SNOW OVER THE
FORECAST AREA WEDNESDAY NIGHT. THIS SYSTEM APPEARS TO HAVE A DECENT
BAROCLINIC ZONE OVER THE PLAINS AND MIDWEST TO WORK WITH. AS FOR THE
FORECAST...HAVE SNOW POPS GOING WEDNESDAY NIGHT THURSDAY.
CONCERNING TEMPERATURES...NO DEEP INTRUSION OF COLD AIR IS EXPECTED
AFTER THE SYSTEM THIS WEEKEND. HOWEVER...MORE COLD AIR COULD BE
DRAWN INTO CENTRAL AFTER THE SYSTEM NEXT WEEK DEPENDING ON HOW
AMPLIFIED IT GETS.
&&
.AVIATION...14/18Z
VFR CONDITIONS ARE EXPECTED THROUGH TODAY WITH SOUTHERLY
WINDS INCREASING THIS AFTERNOON AS THE NEXT WEATHER SYSTEM
APPROACHES FROM THE SOUTHWEST. CEILINGS WILL LOWER THROUGHOUT THE
EVENING BUT SHOULD REMAIN VFR UNTIL AROUND MIDNIGHT WHEN WIDESPREAD
RAIN MOVES INTO THE STATE. CURRENTLY HAVE ONLY LOWERED CEILINGS AND
VISIBILITIES AT MOST SITES TO LOW MVFR...BUT LIKELY ANTICIPATE IFR
CONDITIONS AT TIMES DURING THE EVENT. THE RAIN BEGINS TO PULL OUT BY
MID MORNING TOMORROW BUT LOW STRATUS LOOKS TO REMAIN IN PLACE
THROUGH MUCH OF THE DAY.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...KS
AVIATION...KS
LONG TERM...JOHNSON
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
308 PM CST FRI DEC 14 2012
.SYNOPSIS...
12Z UA ANALYSIS HAS SEVERAL WEAK TROFS FROM THE MID MISSISSIPPI
VALLEY BACK INTO NORTHERN MEXICO. A PLUME OF MOISTURE WAS STREAMING
NORTH ON A LLJ FROM TEXAS INTO SOUTHERN KANSAS. SATELLITE DATA
SHOWED PLENTY OF MID AND HIGH LEVEL CLOUDS STREAMING NORTHEAST
THROUGH THE PLAINS WITH LOW CLOUDS AS FAR NORTH AS EASTERN KANSAS
AND CENTRAL MISSOURI. RADARS SHOW PRECIPITATION IS BREAKING OUT OVER
MORE OF THE PLAINS.
18Z SFC ANALYSIS HAD A DEVELOPING WARM FRONT RUNNING FROM THE
NEBRASKA/SOUTH DAKOTA BORDER EAST INTO NORTHERN INDIANA. DEW POINTS
WERE GENERALLY IN THE 20S ACROSS THE MIDWEST BUT A PLUME OF HIGHER
DEW POINTS RAN FROM TEXAS INTO KANSAS AND EASTERN NEBRASKA.
&&
.SHORT TERM...TONIGHT AND SATURDAY...
THE QUESTION IS NOT IF IT WILL RAIN BUT WHEN.
INITIALLY THERE IS A DRY ATMOSPHERE ACROSS THE AREA THAT WILL NEED
TO SATURATE BEFORE PRECIPITATION BEGINS. TRENDS FROM THE RAP AND
OTHER MODELS GENERALLY AGREE THAT SATURATION WILL OCCUR FAIRLY
QUICKLY DURING THE EVENING HOURS.
THE RAP TRENDS INDICATE CONDENSATION PRESSURE DEFICITS IN THE
850-700MB LAYER WILL COLLAPSE DURING THE EVENING HOURS BUT REMAIN
HIGH IN THE 1000-850MB LAYER. THE OVERALL FORCING INCREASES DURING
THIS TIME WITH F VECTOR CONVERGENCE ALSO DEVELOPING. THUS WHILE THE
AREA WILL START OUT DRY...BY MID EVENING ISOLD SHRA SHOULD BREAK OUT
ACROSS THE SOUTHWEST THIRD OF THE CWFA WITH SPRINKLES POSSIBLE OVER
ALL BUT THE FAR NORTH/NORTHEAST PARTS OF THE CWFA. BY MIDNIGHT
CONDENSATION PRESSURE DEFICITS IN THE 1000-850MB LAYER COLLAPSE SO
SHRA WILL RAPIDLY BECOME MORE NUMEROUS.
AFTER MIDNIGHT...NEARLY ALL THE MODELS SHOW A SIGNIFICANT WING OF
ISENTROPIC LIFT MOVING THROUGH WITH WAA PRECIPITATION. THE LIFT TOOL
SHOWS A SIGNIFICANT THETA E GRADIENT MOVING THROUGH THE CWFA BUT THE
INFERRED TRIPLE POINT SHOULD MOVE FROM KUIN TO KPIA. THUS THE
PRECIPITATION SHOULD STRATIFORM OUT ACROSS THE CWFA AFTER MIDNIGHT.
ANY CONVECTION WITH TSRA SHOULD REMAIN TO THE SOUTH AND EAST OF THE
CWFA.
SATURDAY MORNING THE WAA WING OF ISENTROPIC LIFT MOVES OUT OF THE
CWFA ALLOWING A DECREASE IN THE OVERALL INTENSITY OF THE RAINFALL.
THE DRY SLOT IS PROGGED TO MOVE INTO THE CWFA DURING THE MORNING BUT
FCST SOUNDINGS SHOW CONSIDERABLE LOW LEVEL MOISTURE BELOW IT. THUS
THE DRY SLOT LOOKS TO BE DIRTY WITH PLENTY OF CLOUDS WITH
PRECIPITATION BECOMING MORE SHOWERY BY LATE MORNING AND AFTERNOON.
THE UNSEASONABLY WARM TEMPERATURES WILL CONTINUE WITH MAX
TEMPERATURES WELL ABOVE NORMAL.
OVERALL...GIVEN THE SPEED OF THE SYSTEM...IT APPEARS THAT A GENERAL
RAINFALL OF AROUND ONE HALF INCH SHOULD OCCUR WITH THIS STORM
SYSTEM. ..08..
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY...
SATURDAY NIGHT AND SUNDAY THE MAIN FOCUS IS ON THE EXITING SYSTEM
OFF TO THE NORTHEAST. SATURDAY NIGHT WE SHOULD HAVE A SECONDARY
WAVE AND A TROWAL LIKE FEATURE MOVE ACROSS EASTERN IOWA AND NORTHERN
ILLINOIS IN THE WAKE OF THE MAIN FEATURE TONIGHT AND SATURDAY.
LINGERING LOW AND MID LEVEL MOISTURE SHOULD ALLOW THIS FEATURE TO
PRODUCE SOME RAIN SHOWERS CONTINUING INTO SUNDAY MORNING BEFORE IT
FINALLY MOVES OFF TO THE EAST. THIS WILL BE VERY COLD RAIN...AND
ONLY A SMALL CHANGE IN THE THERMAL PARAMETERS COULD CAUSE SOME
MIXTURE WITH SNOW OR SLEET...BUT THIS LOOKS UNLIKELY FOR NOW.
TEMPERATURES THROUGH THE PERIOD TO CONTINUE TO FALL WITH HIGHS ON
SUNDAY RANGING FROM AROUND 40 NORTHWEST TO THE MID 40S.
MONDAY ANOTHER UPPER LEVEL TROUGH AXIS WILL MOVE ACROSS THE
MIDWEST...BUT THE VORT MAXIMUM WILL MOVE ACROSS SOUTHERN
MISSOURI...AND WE WILL MISS ANY PRECIPITATION FROM THIS WAVE.
HOWEVER...THIS WILL KEEP THE COLDER AIR OVER THE REGION AND HIGHS ON
MONDAY WILL ONLY BE IN THE MID 30S TO LOW 40S. THIS IS STILL ABOVE
NORMAL...SO COLDER IS A RELATIVE TERM.
WARM AIR ADVECTION AND RETURN FLOW SETS IN THEN FOR TUESDAY AND MOST
OF WEDNESDAY...WITH HIGHS BY WEDNESDAY IN THE 40S NEARLY EVERYWHERE.
MODELS ARE DEPICTING A STORM SYSTEM MOVING ACROSS THE MIDWEST DURING
THE MIDDLE OF THE WEEK...CURRENTLY SET TO AFFECT THE FORECAST AREA
WEDNESDAY NIGHT AND THURSDAY. THERE HAS BEEN A LOT OF VARIABILITY
WITH THIS STORM...BOTH IN THE AMOUNT OF PHASING AS THE UPPER LEVEL
TROUGH AXIS COMES ACROSS THE MIDWEST...AND IN THE STRENGTH AND
TIMING OF THE FEATURE. THUS...THE CONSENSUS FORECAST STILL SEEMS
LIKE THE BEST SOLUTION FOR NOW AND HAVE MAINTAINED THE CHANCE POPS
GOING FOR THAT PERIOD...FOLLOWED BY ANOTHER SHOT OF RELATIVELY
COLDER AIR FOR FRIDAY. BY THE SOLSTICE NEXT FRIDAY...WE MIGHT
ACTUALLY HAVE TEMPERATURES NEAR NORMAL. LE
&&
.AVIATION.../ISSUED 1134 AM CST THU DEC 14 2012/
VFR WX WILL BE SEEN THROUGH 00Z/15 AS A FRONT MOVES NORTH INTO
MINNESOTA AND WISCONSIN. AFT 00Z/15 CONDITIONS WILL INITIALLY
DETERIORATE SLOWLY BUT THEN RAPIDLY DETERIORATE TO MVFR CONDITIONS
AFT 04Z/15 WITH POSSIBLE IFR CONDITIONS PRIOR TO SUNRISE DEC 15TH.
MVFR/IFR CONDITIONS ARE EXPECTED TO PERSIST PAST 12Z/15. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
08/LE
AREA FORECAST DISCUSSION
NWS TOPEKA KS
305 PM CST FRI DEC 14 2012
.DISCUSSION...
SHORT TERM (TONIGHT THROUGH SATURDAY)...
AN UPPER LEVEL TROUGH...CURRENTLY OVER EASTERN AZ AT 19Z...WILL LIFT
NORTHEAST ACROSS THE STATE OF KS TONIGHT...THEN NORTHEAST INTO
SOUTHERN WI BY LATE SATURDAY AFTERNOON.
AS THE UPPER LEVEL TROUGH APPROACHES SOUTHWEST KS THIS EVENING THE
STRONGER ASCENT AHEAD OF THE H5 TROUGH WILL SPREAD NORTHEAST ACROSS
THE STATE AND WILL CAUSE SHOWERS AND PERHAPS SOME ISOLATED
THUNDERSTORMS TO DEVELOP ACROSS CENTRAL AND SOUTHERN KS LATE THIS
AFTERNOON...THEN SPREAD NORTHEAST ACROSS THE CWA TONIGHT. THE FIRST
BAND OF LIGHT RAIN WAS DEVELOPING FROM DDC TO ENID...OK AND EXTENDED
NORTHEAST TO ICT. THIS AREA OF RAIN WILL REACH THE SOUTHWEST
COUNTIES OF THE CWA BY 5 TO 6 PM CST...AND THEN CONTINUE TO DEVELOP
NORTHEAST AS LOW-LEVEL WAA/ISENTROPIC LIFT INCREASES AND THE
STRONGER ASCENT AHEAD OF THE H5 TROUGH AXIS SHIFTS NORTHEAST ACROSS
EASTERN KS.
EXPECT PERIODS OF LIGHT RAIN AND RAIN SHOWERS TO CONTINUE THROUGH
THE NIGHT. THE NAM AND HRRR MODEL CONTINUE TO SHOW 100-250 J/KG OF
MUCAPE DEVELOPING ACROSS EASTERN KS FROM 0Z THROUGH ABOUT 8Z...THUS
WE COULD SEE ISOLATED ELEVATED THUNDERSTORMS TO DEVELOP THROUGH THE
EVENING HOURS. EVEN THOUGH THE VERTICAL WINDSHEAR WILL BE STRONG THE
INSTABILITY WILL BE WEAK ENOUGH SO THAT ANY ELEVATED THUNDERSTORMS
THAT MANAGE TO DEVELOP WILL PROBABLY NOT BE INTENSE ENOUGH TO
PRODUCE HAIL. MOST AREAS OF THE CWA SHOULD RECEIVE ABOUT THREE TENTH
OF AN INCH OF RAIN WITH SOME AREAS GETTING CLOSE TO A HALF OF AN
INCH.
AFTER 9Z...THE UPPER LEVEL TROUGH WILL MOVE INTO NORTHEAST KS. THE
700MB DRY SLOT WILL MOVE NORTHEAST ACROSS MUCH OF THE EASTERN HALF
OF THE CWA. THUS...MOST OF THE MEASURABLE RAIN ACROSS THE EASTERN
CWA WILL SHIFT NORTHEAST MO. A WEAK TROWAL WILL DEVELOP ACROSS
SOUTHWEST AND CENTRAL KS AND TRANSLATE NORTHEASTWARD ACROSS NORTH
CENTRAL KS...KEEPING THE LIGHT RAIN GOING FOR THE WESTERN AND
EXTREME NORTHEAST COUNTIES THROUGH THE EARLY MORNING HOURS. AS THE
H5 TROUGH AXIS LIFTS NORTHEAST INTO CENTRAL IA...THE WRAP AROUND
MOISTURE WILL SHIFT NORTHEAST INTO EASTERN NE AND WESTERN IA DURING
THE MID MORNING HOURS.
THERE MAY BE SOME BREAKS IN THE CLOUDS DURING THE LATE MORNING AND
EARLY AFTERNOON HOURS. A LESS AMPLIFIED UPPER LEVEL TROUGH WILL MOVE
EAST FROM THE FOUR CORNERS REGION INTO THE CENTRAL HIGH PLAINS. THIS
TROUGH WILL PROVIDE STRONG ENOUGH ASCENT FOR THE CLOUDS TO INCREASE
ACROSS THE CWA DURING THE AFTERNOON HOURS.
HIGHS ON SATURDAY WILL DEPEND ON HOW MUCH INSOLATION WE WILL
RECEIVE. I EXPECT MOSTLY CLOUDY SKIES THROUGH THE DAY WITH HIGH
TEMPERATURES IN THE LOWER TO MID 50S...THOUGH IF WE SEE MORE
INSOLATION IN THE EARLY AFTERNOON THEN HIGHS MAY BE A FEW DEGREES
HIGHER.
GARGAN
&&
.LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)...
A SECONDARY UPPER TROUGH WILL MOVE ACROSS THE NORTHERN AND CENTRAL
PLAINS. MOISTURE IS LIMITED WITH THIS SYSTEM AND FORCING IS MOST
PRONOUNCED 00Z-06Z ACROSS NORTHERN KANSAS. WILL CONTINUE TO MENTION
SOME SPRINKLES SATURDAY EVENING. LOWS SUNDAY MORNING WILL RANGE FROM
THE MID 20S NORTH CENTRAL TO THE LOWER 30S SOUTHEAST.
ANOTHER SHORTWAVE TROUGH WILL MOVE THROUGH SUNDAY NIGHT AND MONDAY.
MOISTURE IS MEAGER AND FORCING AND MOISTURE ARE BETTER TO THE EAST
OF THE FORECAST AREA. THIS WILL BE FOLLOWED BY MIDLEVEL RIDGE
BUILDING OVER THE PLAINS AS A LONG WAVE TROUGH MOVES INTO THE
WESTERN STATES FROM THE EASTERN PACIFIC. TEMPERATURES WILL BE NEAR
TO ABOVE NORMAL SUNDAY THROUGH TUESDAY.
OPERATIONAL MEDIUM RANGE MODELS AND ENSEMBLES MOVE A COLD UPPER LOW
ACROSS THE CENTRAL PLAINS WEDNESDAY NIGHT AND EARLY THURSDAY.
FORECAST SOUNDINGS INDICATE THAT THERE WILL BE SATURATION IN THE
SNOW GROWTH REGION ON THE SOUNDINGS. HAVE INSERTED A SMALL
PROBABILITY OF LIGHT SNOW FOR WEDNESDAY NIGHT AND EARLY TUESDAY. DRY
ON FRIDAY WITH LARGE SCALE SUBSIDENCE WITH DRY NORTHWEST FLOW. HIGHS
ON FRIDAY NEAR NORMAL IN THE LOW TO MID 40S.
53
&&
.AVIATION...
CLOUDS BEGINNING TO BUILD IN FROM THE SOUTH AHEAD OF THE NEXT SYSTEM
REACHING THE TAF SITES BY EARLY THIS AFTERNOON. STILL ON TRACK FOR
WIDESPREAD SHOWERS WHICH WILL DEVELOP LATER THIS EVENING AS THE MID
LEVEL SYSTEM AND ASSOCIATED FORCING PASSES OVER THE REGION CAUSING
MVFR CIGS AND VSBY ONCE THE PRECIP MOVES IN. THERE IS STILL A
POTENTIAL FOR ISOLATED THUNDER GIVEN THE POSSIBILITY OF SOME WEAK
INSTABILITY ALTHOUGH CONFIDENCE IS LOW ATTM TO INCLUDE IN TAFS.
DEPENDING ON THE INTENSITY OF THE RAINFALL THERE MAY BE TEMPORARY
IFR CIGS AND VSBY BUT WILL ALLOW LATER SHIFTS EVALUATE AS THE EVENT
IS CLOSER.
SANDERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
250 PM CST FRI DEC 14 2012
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 246 PM CST FRI DEC 14 2012
THE MAIN FORECAST CHALLENGES ARE RAIN CHANCES INTO THIS EVENING.
A STRONG, PROGRESSIVE, AND NEGATIVELY TILTED SHORTWAVE TROUGH IS ON
TRACK BY MODELS TO QUICKLY LIFT NORTHEASTWARD FROM EASTERN COLORADO
AND THE TEXAS PANHANDLE TONIGHT, AND INTO EASTERN KANSAS AND
OKLAHOMA BY MIDNIGHT. LIGHT RAIN SHOWERS AND AN ISOLATED
THUNDERSTORM OR TWO WILL CONTINUE TO DEVELOP INTO THE AFTERNOON,
THEN INCREASE IN AREAL COVERAGE BY 5 TO 6 PM AS THE BEST DYNAMIC
LIFT ASSOCIATED WITH THE UPPER TROUGH MOVES INTO WESTERN KANSAS.
WILL CARRY LIKELY CHANCES FOR RAIN UNTIL THE SHORTWAVE LIFTS RAPIDLY
NORTHEASTWARD OUT OF WESTERN KANSAS. THE PRECIPITATION SHOULD END BY
AROUND 9 PM FROM SCOTT CITY TO NEAR DODGE CITY AND MEADE THEN BY
AROUND MIDNIGHT IN THE HAYS AREA. RAINFALL AMOUNTS COULD RANGE FROM
.10 TO .25 INCHES. THE 16Z HRRR MODEL SHOWING AROUND AN INCH
POSSIBLE IN THE STRONGEST SHOWERS AND THUNDERSTORMS, BUT THINKING
THAT COULD BE VERY LOCALIZED AND A BIT OVERDONE. SKIES WILL CLEAR
RAPIDLY FROM WEST TO EAST BEHIND THE SYSTEM AND SOUTH TO
SOUTHEASTERLY WINDS WILL BECOME SOUTHWEST TO WESTERLY BY MORNING.
SURFACE LOW PRESSURE WILL MOVE OUT OF COLORADO AND INTO EXTREME
NORTH CENTRAL KANSAS AFTER MIDNIGHT. THE WINDS WILL STAY ON THE
BREEZY SIDE FROM 15 TO 25 MPH. OVERNIGHT LOWS WILL BE FAIRLY MILD
WITH GOOD MIXING MUCH OF THE NIGHT AND RANGE FROM THE LOWER TO
MID 30S.
FOR SATURDAY A SECONDARY WEAKER UPPER LEVEL SHORTWAVE MOVES ACROSS
WESTERN KANSAS IN THE AFTERNOON WITH MODELS SHOWING INCREASING MID
LEVEL CLOUDS, BUT NO PRECIPITATION. A TRAILING WEAK TROUGH OF
SURFACE LOW PRESSURE WILL BE FOUND ACROSS THE CENTRAL PLAINS. HIGHS
WILL BE IN THE LOW TO MID 50S AND THESE NUMBERS LOOK CLOSE TO
GUIDANCE.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 222 PM CST FRI DEC 14 2012
SATURDAY NIGHT:
A WEAK UPPER LEVEL WAVE IS EXPECTED TO TRAVERSE ACROSS WESTERN
KANSAS SATURDAY EVENING. SOME OF THE MODELS, SUCH AS THE GFS, ARE
INDICATING LIGHT QPF ACROSS SW KANSAS SATURDAY EVENING. THIS
ACTIVITY IS PROBABLY IN RESPONSE TO THE AFOREMENTIONED UL DISTURBANCE.
FORECAST SOUNDINGS ACROSS THE REGION SHOW THAT THIS MOISTURE IS
ABOVE 700 HPA AND THAT THE LOWER LEVELS ARE DRY AND MIXED. AS A
RESULT, WILL CONTINUE WITH SILENT CHANCES OF PRECIPITATION IN THE
GRIDS. LATER SHIFTS COULD ADD FLURRIES AND/OR SPRINKLES LATER, BUT
I DO NOT HAVE ENOUGH CONFIDENCE TO ADD THIS IN ATTM GIVEN THE VERY
DRY LOW LEVELS. OTHERWISE, OVERNIGHT LOWS IN THE 20S AND 30S DEG F
ARE EXPECTED THROUGH THE OVERNIGHT HOURS.
SUNDAY:
AN UPPER LEVEL SHORTWAVE TROF WILL MOVE ACROSS WESTERN KANSAS
SUNDAY. THIS FEATURE WILL USHER THE PASSAGE OF A WEAK SURFACE COLD
FRONT. WEAK TEMPERATURE ADVECTION IS EXPECTED WITH THIS FRONT. THE
NET RESULT WILL BE COOLER TEMPERATURES - GENERALLY IN THE UPPER
40S DEG F. NO PRECIPITATION IS EXPECTED WITH THE FRONT.
MONDAY AND BEYOND:
HAVE WARMED TEMPERATURES MONDAY AS A DOWNSLOPE FLOW IS EXPECTED
ACROSS SW KANSAS WITH 850 HPA TEMPERATURES WARMING TO AROUND 5 DEG
C. BOTH GFS AND ECMWF MOS GUIDANCE ALSO SUPPORT WARMER
TEMPERATURES WITH VALUES PEAKING IN THE LOWER 50S DEG F. ON
TUESDAY, UPPER LEVEL RIDGING IS EXPECTED ACROSS THE CENTRAL PLAINS WITH
A STRENGTHENING LEE SURFACE TROF ACROSS EASTERN COLORADO. THIS
WILL RESULT IN ABOVE AVERAGE TEMPS WITH VALUES IN THE MID 50S DEG
F. THE FORECAST WILL CONTINUE TO REMAIN DRY.
THE NEXT ITEM OF INTEREST IS FOR THURSDAY AS THE 14.12Z ECMWF/GFS
INDICATE A FAIRLY STRONG COLD FRONT TRAVERSING ACROSS THE KANSAS.
THE MAIN IMPACTS FROM THE FRONT IS WINDY CONDITIONS AND COOLER
TEMPERATURES. THERE COULD BE SOME FLURRIES WITH THIS FRONT IN
ASSOCIATION WITH AN ENHANCED AREA OF 700 HPA OMEGA. DUE TO RECENT
POOR PERFORMANCE OF THE MODELS RECENTLY, WILL CONTINUE WITH A DRY
FORECAST AS CONFIDENCE IS VERY LOW. OFFSHORE FLOW IS EXPECTED ACROSS
THE GULF OF MEXICO DURING THE TUESDAY AND WEDNESDAY TIME FRAME.
THIS SHOULD PREVENT SIGNIFICANT MOISTURE FROM RETURNING TO KANSAS.
BEYOND THURSDAY, THE GFS/ECMWF ARE IN FAIRLY AGREEMENT WITH UPPER
LEVEL RIDGING ACROSS THE ROCKIES. THE RESULTANT NW FLOW ALOFT
ACROSS WESTERN KANSAS IS NOT CONDUCIVE FOR SIGNIFICANT
PRECIPITATION. TEMPERATURES WILL CONTINUE TO REMAIN NEAR TO ABOVE
AVERAGE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1114 AM CST FRI DEC 14 2012
CIGS WILL CONTINUE TO LOWER FROM OVC100 TO MVFR THIS AFTERNOON
WITH SOME LIGHT SHOWERS OR ISOLATED THUNDERSTORMS DEVELOPING
AROUND 22-00Z. A STRONG UPPER LEVEL SHORTWAVE TROUGH WILL MOVE
ACROSS WESTERN KANSAS THIS EVENING ENDING THE LIGHT RAIN SHOWERS
AND ISOLATED THUNDERSTORMS BY 03Z AT KGCK AND KDDC, AND AROUND 06Z
AT KHYS WITH CIGS RAPIDLY IMPROVING TO VFR. SOUTH TO SOUTHEASTERLY
WINDS OF 15-25KT WILL BECOME SOUTHWESTERLY TO WESTERLY TONIGHT AT
12-22KT AS A SURFACE LOW MOVES EAST INTO NORTH CENTRAL KANSAS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 35 55 29 48 / 70 0 10 10
GCK 33 54 27 47 / 60 0 10 10
EHA 33 56 29 49 / 50 0 10 10
LBL 35 57 30 49 / 70 0 10 10
HYS 35 53 26 47 / 70 0 10 10
P28 38 60 32 51 / 60 0 0 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KRUSE
LONG TERM...SUGDEN
AVIATION...KRUSE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1147 AM MST FRI DEC 14 2012
UPDATE ISSUED AT 1147 AM MST FRI DEC 14 2012
LIGHT RAIN HAS BEGUN REACHING THE GROUND ACROSS PORTIONS OF KIT
CARSON AND YUMA COUNTY COLORADO. GRIDS HAVE BEEN UPDATED TO
REFLECT CURRENT TRENDS. SCATTERED ECHOES HAVE ALSO BEGUN TO
INCREASE ACROSS THE REST OF THE CWA AND EXPECT PRECIPITATION TO
INCREASE OVER THE NEXT FEW HOURS. WARM FRONT HAS FINALLY BEGUN TO
NUDGE INTO THE SOUTHERN COUNTIES OF CWA INCREASING TEMPERATURES
AND WILL GRADUALLY RAISE DEWPOINTS INTO THE 30S THROUGH THE
AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 342 AM MST FRI DEC 14 2012
MAIN FORECAST CONCERN WILL BE STORM SYSTEM THAT WILL IMPACT THE AREA
THROUGH TONIGHT. SATELLITE SHOWING A PROGRESSIVE NEARLY ZONAL FLOW
FROM THE PACIFIC INTO THE WESTERN ATLANTIC. THE EXCEPTION TO THIS
IS THE SYSTEM THAT IS CUT OFF FROM THE FLOW AND EXTENDS FROM NEVADA
TO JUST OFF THE SOUTHERN CALIFORNIA COAST. THROUGH 05Z THIS SYSTEM
WAS STILL DIGGING AND NOT MAKING ANY PROGRESS EAST YET. THIS TROUGH
HAS PULLED UP SUBTROPICAL MOISTURE AHEAD OF IT.
AT JET LEVEL...THE NAM...UKMET AND SREF LOOK TO HAVE THE JET SEGMENT
COMING IN FROM THE SOUTHWEST THE BEST. OTHER MODELS TENDED TO HAVE
THE HIGHER SPEEDS TOO FAR NORTH OR EAST. AT MID LEVELS...WITH THE
INCOMING UPPER TROUGH...MODELS TENDED TO BE TOO FAR SOUTH AND EAST.
THE GFS AND CANADIAN WERE DOING A LITTLE BETTER THAN THE SREF AND
NAM. MODELS ALSO TENDED TO BE TOO GENEROUS WITH THE MID LEVEL
MOISTURE. MODELS ARE HAVING A HARD CATCHING THE SUBTLE COLD FRONT
THAT SAGGED OVER THE AREA TODAY. THE NAM AND RUC WERE DOING THE
BEST. ALSO MODELS ARE TOO GENEROUS WITH LOW LEVEL MOISTURE WITH THE
HIGHER DEWPOINTS TOO FAR NORTH ALREADY. THE GFS AND CANADIAN WERE
DOING THE BEST ON THE LOW LEVEL THERMAL FIELD.
TODAY/TONIGHT...LEFT FRONT QUADRANT OF THE JET CONTINUES TO MOVE
CLOSE TO AREA AND AFFECTS THE AREA MAINLY FROM 12Z TO 18Z. DURING
THAT TIME IT LOOKS LIKE THERE IS NOT A LOT OF LOW LEVEL MOISTURE BUT
LITTLE MOISTURE IN THE COLUMN. SURFACE OBSERVATIONS AND 00Z SOUNDINGS
TO OUR SOUTH ARE VERY DRY. BY THE TIME THE MOISTURE GETS HERE...THE
MAIN JET IS WELL EAST. SPEAKING OF MOISTURE RETURN...DEWPOINTS
REMAIN VERY LOW AND THERE IS NO SIGNIFICANT INCREASE IN MOISTURE
UNTIL WELL SOUTH. MODELS ARE OVERDOING MOISTURE RETURN RIGHT NOW.
00Z SOUNDINGS OVER OUR AREA AND TO THE SOUTH ARE EXTREMELY DRY.
MOISTURE TRAJECTORIES WOULD SUPPORT BEST MOISTURE FURTHER SOUTH AND
EAST. ALSO THUNDERSTORMS WILL BE DEVELOPING TO OUR SOUTH AND EAST
AND SLOW DOWN OR ROB ANY MOISTURE RETURN WE WERE GOING TO SEE.
DUE TO THE SUBTROPICAL MOISTURE RETURN...THERE LOOKS TO BE A
SIGNIFICANT MID/UPPER LEVEL CLOUD DECK WHICH WILL INHIBIT HEATING
AND ANY SURFACE INSTABILITY. MODELS ARE ALSO SHOWING LITTLE TO NO
ELEVATED CAPE AS WELL. WITH MODELS OVERDOING THE INFLUX OF MOISTURE
MODELS ARE PROBABLY OVERDOING ANY INSTABILITY AS WELL. SO CHOSE TO
KEEP THUNDER OUT OF THE FORECAST.
00Z MODEL DATA WAS HINTING AT IT AND NOW 06Z IS CATCHING ONTO IT
EVEN MORE. THE MODELS STILL BRING THE SYSTEM ACROSS IN A NEGATIVE
TILT. HOWEVER...THEY BRING IT ACROSS WITH A NORTHERN AND SOUTHERN
CIRCULATION ON EITHER SIDE OF THE FORECAST AREA. MODELS HAVE BACKED
THEIR IDEA OF ANY WRAP AROUND ON THE BACKSIDE OF THE SYSTEM. PLUS
MODELS HAVE PUSHED EASTERN BAND OF PRECIPITATION FURTHER SOUTH AND
EAST. SO IN A NUTSHELL BEST MOISTURE...LIFT...AND INSTABILITY ARE
NOT INSYNC OR NOT THERE. AT THIS TIME IT STILL DOES LOOK LIKE THE
NORTHEAST PORTION OF THE AREA WILL HAVE THE BEST CHANCE FOR
MEASURABLE PRECIPITATION WITH LITTLE TO NONE FURTHER SOUTHWEST AND
WEST YOU GO.
NEW MODEL GUIDANCE SLOWED THINGS DOWN ON PRECIPITATION ARRIVAL AND
LIMITED POPS TO THE AFTERNOON AND TIERED THEM FROM LOWEST TO HIGHEST
PER REASONING ABOVE. BELIEVE PRECIPITATION WILL SHUT OFF PRETTY QUICK
GIVEN THE SPEED OF THE SYSTEM AND MODEL DEFICIENCIES MENTIONED
ABOVE. BELIEVE MOST OF THE PRECIPITATION WILL BE DOWN BY OR SHORTLY
AFTER 06Z. DID HOLD ONTO PRECIPITATION AFTER THAT JUST KEEP WITHIN
SOME CLOSENESS WITH MY NEIGHBORS. IN REGARDS TO PHASE. LOOKS LIKE IT
STAYS RAIN THROUGH THE DAY. MODEL SOUNDINGS INDICATE TEMPERATURES
STAYING ABOVE FREEZING FOR MOST OF THE NIGHT EVEN IF THERE IS ICE IN
THE COLUMN. SOUNDINGS ARE ALSO NOT OPTIMISTIC ABOUT ICE IN THE
COLUMN EITHER. IT ALSO LOOKS BY THE TIME THE AIR MASS GETS COLD
ENOUGH TO SUPPORT SNOW...THE LIFT AND MOISTURE ARE GONE. SO ONLY
HAVE A MIX OF RAIN AND SNOW AT BEST. THEREFORE THERE SHOULD BE
LITTLE TO NO SNOW ACCUMULATION.
PRIOR TO ARRIVAL OF CLOUDS TEMPERATURES HAVE COOLED OFF
DRAMATICALLY THIS MORNING WITH MODELS TOO WARM. COMBINATION OF
UNFAVORABLE WIND FIELD AND INCREASING CLOUD COVER/DEVELOPING
PRECIPITATION WILL KEEP TEMPERATURES FROM WARMING MUCH. BELIEVE THE
GEM WAS CATCHING THE IDEA THE BEST AND I MAY BE TOO WARM.
SATURDAY/SATURDAY NIGHT...TRICKY MAX TEMPERATURE FORECAST. NORTHWEST
WINDS AND SOME SUN EARLY WILL ALLOW FOR TEMPERATURES TO WARM. BUT
NEXT SHORTWAVE TROUGH WILL DRAMATICALLY INCREASE CLOUD COVER IN THE
AFTERNOON. CHOSE TO TOWARD THE COOLER SIDE. FOR THE NIGHT MODELS
STILL PRODUCING QPF. MODELS DIFFER ON WHERE TO PUT IT BUT GENERALLY
FAVOR THE SOUTHWEST. NOT UNREASONABLE FOR PRECIPITATION TO OCCUR
ANYWHERE BUT AM NOT TOTALLY SOLD ON ANYTHING OCCURRING. SO
BROADBRUSHED LOW SLIGHT CHANCE POPS FOR THE ENTIRE AREA.
SUNDAY/SUNDAY NIGHT...AGAIN LIGHT WIND FIELD AND INCREASING CLOUD
COVER WILL CREATE FOR A TRICKY HIGH TEMPERATURE FORECAST. MODELS
INDICATE A COOLER AIR MASS THAN ON SATURDAY. TRENDED COOLER OR
TOWARD COOLER GUIDANCE.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 342 AM MST FRI DEC 14 2012
AN UPPER LEVEL RIDGE WILL MOVE OVER THE AREA THE FIRST PART OF NEXT
WEEK. FOLLOWING THE RIDGE WILL BE A SHORT WAVE TROUGH...WHICH WILL
APPROACH THE AREA WEDNESDAY. AHEAD OF THE TROUGH THERE MAY BE A
CHANCE FOR SOME PRECIPITATION WEDNESDAY AS A COLD FRONT MOVES
THROUGH. AT THIS TIME MODELS DISAGREE WITH THE TIMING OF THE FRONT
BY AS MUCH AS 12 HOURS. IN ADDITION...LIFT ALONG THE FRONT DOES NOT
LOOK STRONG ENOUGH AT THIS POINT TO DEVELOP ANY PRECIPITATION AND
THE ENVIRONMENT MOISTENS BEHIND THE FRONT WHERE THERE IS ALMOST NO
LIFT. IF MODELS COME INTO A BETTER AGREEMENT WITH THE FRONTAL
PASSAGE...AND IF THE LIFT ALONG THE FRONT WILL STRENGTHEN WITH A
BETTER SUPPLY OF MOISTURE...A MENTION OF PRECIPITATION WILL THEN BE
WARRANTED.
TEMPERATURES FOR THE PERIOD WILL WARM THROUGH WEDNESDAY AHEAD OF THE
COLD FRONT...WITH VALUES 10 TO 15 DEGREES ABOVE NORMAL. AFTER THE
COLD FRONT TEMPERATURES RETURN TO NEAR NORMAL VALUES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1036 AM MST FRI DEC 14 2012
TAFS SEEM TO BE ON TRACK FOR LOWER CIGS AND CHANCE OF LIGHT
PRECIPITATION DEVELOPING AT BOTH TERMINALS THIS AFTERNOON AND
OVERNIGHT. UPPER LEVEL TROUGH IS CURRENTLY MOVING ACROSS THE FOUR
CORNERS REGION AND LIGHT PRECIPITATION IS DEVELOPING AND REACHING
THE SURFACE ACROSS PORTIONS OF EASTERN COLORADO. EXPECT
SCATTERED PRECIPITATION TO DEVELOP AT KGLD AROUND 20-21Z WITH
DEVELOPMENT AT KMCK A BIT LATER AROUND 22-23Z. ATTM KMCK LOOKS TO
BE THE BETTER RECIPIENT FOR MEASURABLE PRECIP WHICH MAY BRING
VSBY DOWN TO MVFR FOR A FEW HOURS TONIGHT. CIGS STILL REMAIN A
TRICKY FORECAST WITH MODELS BRINGING KMCK DOWN TO IFR AND MAYBE A
BRIEF PERIOD OF LIFR OVERNIGHT. UPPER LEVEL SYSTEM WILL BE EAST OF
THE AREA BY 06-08Z WITH SKIES GRADUALLY CLEARING THROUGH THE END
OF THE PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...PMM
SHORT TERM...BULLER
LONG TERM...JTL
AVIATION...PMM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1142 AM MST FRI DEC 14 2012
.UPDATE...
ISSUED AT 1136 AM MST FRI DEC 14 2012
LIGHT RAIN HAS BEGUN REACHING THE GROUND ACROSS PORTIONS OF KIT
CARSON AND YUMA COUNTY COLORADO. GRIDS HAVE BEEN UPDATED TO
REFLECT CURRENT TRENDS. SCATTERED ECHOES HAVE ALSO BEGUN TO
INCREASE ACROSS THE REST OF THE CWA AT EXPECT PRECIPITATION TO
INCREASE OVER THE NEXT FEW HOURS. WARM FRONT HAS FINALLY BEGUN TO
NUDGE INTO THE SOUTHERN COUNTIES OF CWA INCREASING TEMPERATURES
AND WILL GRADUALLY RAISE DEWPOINTS INTO THE 30S THROUGH THE AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 342 AM MST FRI DEC 14 2012
MAIN FORECAST CONCERN WILL BE STORM SYSTEM THAT WILL IMPACT THE AREA
THROUGH TONIGHT. SATELLITE SHOWING A PROGRESSIVE NEARLY ZONAL FLOW
FROM THE PACIFIC INTO THE WESTERN ATLANTIC. THE EXCEPTION TO THIS
IS THE SYSTEM THAT IS CUT OFF FROM THE FLOW AND EXTENDS FROM NEVADA
TO JUST OFF THE SOUTHERN CALIFORNIA COAST. THROUGH 05Z THIS SYSTEM
WAS STILL DIGGING AND NOT MAKING ANY PROGRESS EAST YET. THIS TROUGH
HAS PULLED UP SUBTROPICAL MOISTURE AHEAD OF IT.
AT JET LEVEL...THE NAM...UKMET AND SREF LOOK TO HAVE THE JET SEGMENT
COMING IN FROM THE SOUTHWEST THE BEST. OTHER MODELS TENDED TO HAVE
THE HIGHER SPEEDS TOO FAR NORTH OR EAST. AT MID LEVELS...WITH THE
INCOMING UPPER TROUGH...MODELS TENDED TO BE TOO FAR SOUTH AND EAST.
THE GFS AND CANADIAN WERE DOING A LITTLE BETTER THAN THE SREF AND
NAM. MODELS ALSO TENDED TO BE TOO GENEROUS WITH THE MID LEVEL
MOISTURE. MODELS ARE HAVING A HARD CATCHING THE SUBTLE COLD FRONT
THAT SAGGED OVER THE AREA TODAY. THE NAM AND RUC WERE DOING THE
BEST. ALSO MODELS ARE TOO GENEROUS WITH LOW LEVEL MOISTURE WITH THE
HIGHER DEWPOINTS TOO FAR NORTH ALREADY. THE GFS AND CANADIAN WERE
DOING THE BEST ON THE LOW LEVEL THERMAL FIELD.
TODAY/TONIGHT...LEFT FRONT QUADRANT OF THE JET CONTINUES TO MOVE
CLOSE TO AREA AND AFFECTS THE AREA MAINLY FROM 12Z TO 18Z. DURING
THAT TIME IT LOOKS LIKE THERE IS NOT A LOT OF LOW LEVEL MOISTURE BUT
LITTLE MOISTURE IN THE COLUMN. SURFACE OBSERVATIONS AND 00Z SOUNDINGS
TO OUR SOUTH ARE VERY DRY. BY THE TIME THE MOISTURE GETS HERE...THE
MAIN JET IS WELL EAST. SPEAKING OF MOISTURE RETURN...DEWPOINTS
REMAIN VERY LOW AND THERE IS NO SIGNIFICANT INCREASE IN MOISTURE
UNTIL WELL SOUTH. MODELS ARE OVERDOING MOISTURE RETURN RIGHT NOW.
00Z SOUNDINGS OVER OUR AREA AND TO THE SOUTH ARE EXTREMELY DRY.
MOISTURE TRAJECTORIES WOULD SUPPORT BEST MOISTURE FURTHER SOUTH AND
EAST. ALSO THUNDERSTORMS WILL BE DEVELOPING TO OUR SOUTH AND EAST
AND SLOW DOWN OR ROB ANY MOISTURE RETURN WE WERE GOING TO SEE.
DUE TO THE SUBTROPICAL MOISTURE RETURN...THERE LOOKS TO BE A
SIGNIFICANT MID/UPPER LEVEL CLOUD DECK WHICH WILL INHIBIT HEATING
AND ANY SURFACE INSTABILITY. MODELS ARE ALSO SHOWING LITTLE TO NO
ELEVATED CAPE AS WELL. WITH MODELS OVERDOING THE INFLUX OF MOISTURE
MODELS ARE PROBABLY OVERDOING ANY INSTABILITY AS WELL. SO CHOSE TO
KEEP THUNDER OUT OF THE FORECAST.
00Z MODEL DATA WAS HINTING AT IT AND NOW 06Z IS CATCHING ONTO IT
EVEN MORE. THE MODELS STILL BRING THE SYSTEM ACROSS IN A NEGATIVE
TILT. HOWEVER...THEY BRING IT ACROSS WITH A NORTHERN AND SOUTHERN
CIRCULATION ON EITHER SIDE OF THE FORECAST AREA. MODELS HAVE BACKED
THEIR IDEA OF ANY WRAP AROUND ON THE BACKSIDE OF THE SYSTEM. PLUS
MODELS HAVE PUSHED EASTERN BAND OF PRECIPITATION FURTHER SOUTH AND
EAST. SO IN A NUTSHELL BEST MOISTURE...LIFT...AND INSTABILITY ARE
NOT INSYNC OR NOT THERE. AT THIS TIME IT STILL DOES LOOK LIKE THE
NORTHEAST PORTION OF THE AREA WILL HAVE THE BEST CHANCE FOR
MEASURABLE PRECIPITATION WITH LITTLE TO NONE FURTHER SOUTHWEST AND
WEST YOU GO.
NEW MODEL GUIDANCE SLOWED THINGS DOWN ON PRECIPITATION ARRIVAL AND
LIMITED POPS TO THE AFTERNOON AND TIERED THEM FROM LOWEST TO HIGHEST
PER REASONING ABOVE. BELIEVE PRECIPITATION WILL SHUT OFF PRETTY QUICK
GIVEN THE SPEED OF THE SYSTEM AND MODEL DEFICIENCIES MENTIONED
ABOVE. BELIEVE MOST OF THE PRECIPITATION WILL BE DOWN BY OR SHORTLY
AFTER 06Z. DID HOLD ONTO PRECIPITATION AFTER THAT JUST KEEP WITHIN
SOME CLOSENESS WITH MY NEIGHBORS. IN REGARDS TO PHASE. LOOKS LIKE IT
STAYS RAIN THROUGH THE DAY. MODEL SOUNDINGS INDICATE TEMPERATURES
STAYING ABOVE FREEZING FOR MOST OF THE NIGHT EVEN IF THERE IS ICE IN
THE COLUMN. SOUNDINGS ARE ALSO NOT OPTIMISTIC ABOUT ICE IN THE
COLUMN EITHER. IT ALSO LOOKS BY THE TIME THE AIR MASS GETS COLD
ENOUGH TO SUPPORT SNOW...THE LIFT AND MOISTURE ARE GONE. SO ONLY
HAVE A MIX OF RAIN AND SNOW AT BEST. THEREFORE THERE SHOULD BE
LITTLE TO NO SNOW ACCUMULATION.
PRIOR TO ARRIVAL OF CLOUDS TEMPERATURES HAVE COOLED OFF
DRAMATICALLY THIS MORNING WITH MODELS TOO WARM. COMBINATION OF
UNFAVORABLE WIND FIELD AND INCREASING CLOUD COVER/DEVELOPING
PRECIPITATION WILL KEEP TEMPERATURES FROM WARMING MUCH. BELIEVE THE
GEM WAS CATCHING THE IDEA THE BEST AND I MAY BE TOO WARM.
SATURDAY/SATURDAY NIGHT...TRICKY MAX TEMPERATURE FORECAST. NORTHWEST
WINDS AND SOME SUN EARLY WILL ALLOW FOR TEMPERATURES TO WARM. BUT
NEXT SHORTWAVE TROUGH WILL DRAMATICALLY INCREASE CLOUD COVER IN THE
AFTERNOON. CHOSE TO TOWARD THE COOLER SIDE. FOR THE NIGHT MODELS
STILL PRODUCING QPF. MODELS DIFFER ON WHERE TO PUT IT BUT GENERALLY
FAVOR THE SOUTHWEST. NOT UNREASONABLE FOR PRECIPITATION TO OCCUR
ANYWHERE BUT AM NOT TOTALLY SOLD ON ANYTHING OCCURRING. SO
BROADBRUSHED LOW SLIGHT CHANCE POPS FOR THE ENTIRE AREA.
SUNDAY/SUNDAY NIGHT...AGAIN LIGHT WIND FIELD AND INCREASING CLOUD
COVER WILL CREATE FOR A TRICKY HIGH TEMPERATURE FORECAST. MODELS
INDICATE A COOLER AIR MASS THAN ON SATURDAY. TRENDED COOLER OR
TOWARD COOLER GUIDANCE.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 342 AM MST FRI DEC 14 2012
AN UPPER LEVEL RIDGE WILL MOVE OVER THE AREA THE FIRST PART OF NEXT
WEEK. FOLLOWING THE RIDGE WILL BE A SHORT WAVE TROUGH...WHICH WILL
APPROACH THE AREA WEDNESDAY. AHEAD OF THE TROUGH THERE MAY BE A
CHANCE FOR SOME PRECIPITATION WEDNESDAY AS A COLD FRONT MOVES
THROUGH. AT THIS TIME MODELS DISAGREE WITH THE TIMING OF THE FRONT
BY AS MUCH AS 12 HOURS. IN ADDITION...LIFT ALONG THE FRONT DOES NOT
LOOK STRONG ENOUGH AT THIS POINT TO DEVELOP ANY PRECIPITATION AND
THE ENVIRONMENT MOISTENS BEHIND THE FRONT WHERE THERE IS ALMOST NO
LIFT. IF MODELS COME INTO A BETTER AGREEMENT WITH THE FRONTAL
PASSAGE...AND IF THE LIFT ALONG THE FRONT WILL STRENGTHEN WITH A
BETTER SUPPLY OF MOISTURE...A MENTION OF PRECIPITATION WILL THEN BE
WARRANTED.
TEMPERATURES FOR THE PERIOD WILL WARM THROUGH WEDNESDAY AHEAD OF THE
COLD FRONT...WITH VALUES 10 TO 15 DEGREES ABOVE NORMAL. AFTER THE
COLD FRONT TEMPERATURES RETURN TO NEAR NORMAL VALUES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1036 AM MST FRI DEC 14 2012
TAFS SEEM TO BE ON TRACK FOR LOWER CIGS AND CHANCE OF LIGHT
PRECIPITATION DEVELOPING AT BOTH TERMINALS THIS AFTERNOON AND
OVERNIGHT. UPPER LEVEL TROUGH IS CURRENTLY MOVING ACROSS THE FOUR
CORNERS REGION AND LIGHT PRECIPITATION IS DEVELOPING AND REACHING
THE SURFACE ACROSS PORTIONS OF EASTERN COLORADO. EXPECT
SCATTERED PRECIPITATION TO DEVELOP AT KGLD AROUND 20-21Z WITH
DEVELOPMENT AT KMCK A BIT LATER AROUND 22-23Z. ATTM KMCK LOOKS TO
BE THE BETTER RECIPIENT FOR MEASURABLE PRECIP WHICH MAY BRING
VSBY DOWN TO MVFR FOR A FEW HOURS TONIGHT. CIGS STILL REMAIN A
TRICKY FORECAST WITH MODELS BRINGING KMCK DOWN TO IFR AND MAYBE A
BRIEF PERIOD OF LIFR OVERNIGHT. UPPER LEVEL SYSTEM WILL BE EAST OF
THE AREA BY 06-08Z WITH SKIES GRADUALLY CLEARING THROUGH THE END
OF THE PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...PMM
SHORT TERM...BULLER
LONG TERM...JTL
AVIATION...PMM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1054 AM MST FRI DEC 14 2012
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 342 AM MST FRI DEC 14 2012
MAIN FORECAST CONCERN WILL BE STORM SYSTEM THAT WILL IMPACT THE AREA
THROUGH TONIGHT. SATELLITE SHOWING A PROGRESSIVE NEARLY ZONAL FLOW
FROM THE PACIFIC INTO THE WESTERN ATLANTIC. THE EXCEPTION TO THIS
IS THE SYSTEM THAT IS CUT OFF FROM THE FLOW AND EXTENDS FROM NEVADA
TO JUST OFF THE SOUTHERN CALIFORNIA COAST. THROUGH 05Z THIS SYSTEM
WAS STILL DIGGING AND NOT MAKING ANY PROGRESS EAST YET. THIS TROUGH
HAS PULLED UP SUBTROPICAL MOISTURE AHEAD OF IT.
AT JET LEVEL...THE NAM...UKMET AND SREF LOOK TO HAVE THE JET SEGMENT
COMING IN FROM THE SOUTHWEST THE BEST. OTHER MODELS TENDED TO HAVE
THE HIGHER SPEEDS TOO FAR NORTH OR EAST. AT MID LEVELS...WITH THE
INCOMING UPPER TROUGH...MODELS TENDED TO BE TOO FAR SOUTH AND EAST.
THE GFS AND CANADIAN WERE DOING A LITTLE BETTER THAN THE SREF AND
NAM. MODELS ALSO TENDED TO BE TOO GENEROUS WITH THE MID LEVEL
MOISTURE. MODELS ARE HAVING A HARD CATCHING THE SUBTLE COLD FRONT
THAT SAGGED OVER THE AREA TODAY. THE NAM AND RUC WERE DOING THE
BEST. ALSO MODELS ARE TOO GENEROUS WITH LOW LEVEL MOISTURE WITH THE
HIGHER DEWPOINTS TOO FAR NORTH ALREADY. THE GFS AND CANADIAN WERE
DOING THE BEST ON THE LOW LEVEL THERMAL FIELD.
TODAY/TONIGHT...LEFT FRONT QUADRANT OF THE JET CONTINUES TO MOVE
CLOSE TO AREA AND AFFECTS THE AREA MAINLY FROM 12Z TO 18Z. DURING
THAT TIME IT LOOKS LIKE THERE IS NOT A LOT OF LOW LEVEL MOISTURE BUT
LITTLE MOISTURE IN THE COLUMN. SURFACE OBSERVATIONS AND 00Z SOUNDINGS
TO OUR SOUTH ARE VERY DRY. BY THE TIME THE MOISTURE GETS HERE...THE
MAIN JET IS WELL EAST. SPEAKING OF MOISTURE RETURN...DEWPOINTS
REMAIN VERY LOW AND THERE IS NO SIGNIFICANT INCREASE IN MOISTURE
UNTIL WELL SOUTH. MODELS ARE OVERDOING MOISTURE RETURN RIGHT NOW.
00Z SOUNDINGS OVER OUR AREA AND TO THE SOUTH ARE EXTREMELY DRY.
MOISTURE TRAJECTORIES WOULD SUPPORT BEST MOISTURE FURTHER SOUTH AND
EAST. ALSO THUNDERSTORMS WILL BE DEVELOPING TO OUR SOUTH AND EAST
AND SLOW DOWN OR ROB ANY MOISTURE RETURN WE WERE GOING TO SEE.
DUE TO THE SUBTROPICAL MOISTURE RETURN...THERE LOOKS TO BE A
SIGNIFICANT MID/UPPER LEVEL CLOUD DECK WHICH WILL INHIBIT HEATING
AND ANY SURFACE INSTABILITY. MODELS ARE ALSO SHOWING LITTLE TO NO
ELEVATED CAPE AS WELL. WITH MODELS OVERDOING THE INFLUX OF MOISTURE
MODELS ARE PROBABLY OVERDOING ANY INSTABILITY AS WELL. SO CHOSE TO
KEEP THUNDER OUT OF THE FORECAST.
00Z MODEL DATA WAS HINTING AT IT AND NOW 06Z IS CATCHING ONTO IT
EVEN MORE. THE MODELS STILL BRING THE SYSTEM ACROSS IN A NEGATIVE
TILT. HOWEVER...THEY BRING IT ACROSS WITH A NORTHERN AND SOUTHERN
CIRCULATION ON EITHER SIDE OF THE FORECAST AREA. MODELS HAVE BACKED
THEIR IDEA OF ANY WRAP AROUND ON THE BACKSIDE OF THE SYSTEM. PLUS
MODELS HAVE PUSHED EASTERN BAND OF PRECIPITATION FURTHER SOUTH AND
EAST. SO IN A NUTSHELL BEST MOISTURE...LIFT...AND INSTABILITY ARE
NOT INSYNC OR NOT THERE. AT THIS TIME IT STILL DOES LOOK LIKE THE
NORTHEAST PORTION OF THE AREA WILL HAVE THE BEST CHANCE FOR
MEASURABLE PRECIPITATION WITH LITTLE TO NONE FURTHER SOUTHWEST AND
WEST YOU GO.
NEW MODEL GUIDANCE SLOWED THINGS DOWN ON PRECIPITATION ARRIVAL AND
LIMITED POPS TO THE AFTERNOON AND TIERED THEM FROM LOWEST TO HIGHEST
PER REASONING ABOVE. BELIEVE PRECIPITATION WILL SHUT OFF PRETTY QUICK
GIVEN THE SPEED OF THE SYSTEM AND MODEL DEFICIENCIES MENTIONED
ABOVE. BELIEVE MOST OF THE PRECIPITATION WILL BE DOWN BY OR SHORTLY
AFTER 06Z. DID HOLD ONTO PRECIPITATION AFTER THAT JUST KEEP WITHIN
SOME CLOSENESS WITH MY NEIGHBORS. IN REGARDS TO PHASE. LOOKS LIKE IT
STAYS RAIN THROUGH THE DAY. MODEL SOUNDINGS INDICATE TEMPERATURES
STAYING ABOVE FREEZING FOR MOST OF THE NIGHT EVEN IF THERE IS ICE IN
THE COLUMN. SOUNDINGS ARE ALSO NOT OPTIMISTIC ABOUT ICE IN THE
COLUMN EITHER. IT ALSO LOOKS BY THE TIME THE AIR MASS GETS COLD
ENOUGH TO SUPPORT SNOW...THE LIFT AND MOISTURE ARE GONE. SO ONLY
HAVE A MIX OF RAIN AND SNOW AT BEST. THEREFORE THERE SHOULD BE
LITTLE TO NO SNOW ACCUMULATION.
PRIOR TO ARRIVAL OF CLOUDS TEMPERATURES HAVE COOLED OFF
DRAMATICALLY THIS MORNING WITH MODELS TOO WARM. COMBINATION OF
UNFAVORABLE WIND FIELD AND INCREASING CLOUD COVER/DEVELOPING
PRECIPITATION WILL KEEP TEMPERATURES FROM WARMING MUCH. BELIEVE THE
GEM WAS CATCHING THE IDEA THE BEST AND I MAY BE TOO WARM.
SATURDAY/SATURDAY NIGHT...TRICKY MAX TEMPERATURE FORECAST. NORTHWEST
WINDS AND SOME SUN EARLY WILL ALLOW FOR TEMPERATURES TO WARM. BUT
NEXT SHORTWAVE TROUGH WILL DRAMATICALLY INCREASE CLOUD COVER IN THE
AFTERNOON. CHOSE TO TOWARD THE COOLER SIDE. FOR THE NIGHT MODELS
STILL PRODUCING QPF. MODELS DIFFER ON WHERE TO PUT IT BUT GENERALLY
FAVOR THE SOUTHWEST. NOT UNREASONABLE FOR PRECIPITATION TO OCCUR
ANYWHERE BUT AM NOT TOTALLY SOLD ON ANYTHING OCCURRING. SO
BROADBRUSHED LOW SLIGHT CHANCE POPS FOR THE ENTIRE AREA.
SUNDAY/SUNDAY NIGHT...AGAIN LIGHT WIND FIELD AND INCREASING CLOUD
COVER WILL CREATE FOR A TRICKY HIGH TEMPERATURE FORECAST. MODELS
INDICATE A COOLER AIR MASS THAN ON SATURDAY. TRENDED COOLER OR
TOWARD COOLER GUIDANCE.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 342 AM MST FRI DEC 14 2012
AN UPPER LEVEL RIDGE WILL MOVE OVER THE AREA THE FIRST PART OF NEXT
WEEK. FOLLOWING THE RIDGE WILL BE A SHORT WAVE TROUGH...WHICH WILL
APPROACH THE AREA WEDNESDAY. AHEAD OF THE TROUGH THERE MAY BE A
CHANCE FOR SOME PRECIPITATION WEDNESDAY AS A COLD FRONT MOVES
THROUGH. AT THIS TIME MODELS DISAGREE WITH THE TIMING OF THE FRONT
BY AS MUCH AS 12 HOURS. IN ADDITION...LIFT ALONG THE FRONT DOES NOT
LOOK STRONG ENOUGH AT THIS POINT TO DEVELOP ANY PRECIPITATION AND
THE ENVIRONMENT MOISTENS BEHIND THE FRONT WHERE THERE IS ALMOST NO
LIFT. IF MODELS COME INTO A BETTER AGREEMENT WITH THE FRONTAL
PASSAGE...AND IF THE LIFT ALONG THE FRONT WILL STRENGTHEN WITH A
BETTER SUPPLY OF MOISTURE...A MENTION OF PRECIPITATION WILL THEN BE
WARRANTED.
TEMPERATURES FOR THE PERIOD WILL WARM THROUGH WEDNESDAY AHEAD OF THE
COLD FRONT...WITH VALUES 10 TO 15 DEGREES ABOVE NORMAL. AFTER THE
COLD FRONT TEMPERATURES RETURN TO NEAR NORMAL VALUES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1036 AM MST FRI DEC 14 2012
TAFS SEEM TO BE ON TRACK FOR LOWER CIGS AND CHANCE OF LIGHT
PRECIPITATION DEVELOPING AT BOTH TERMINALS THIS AFTERNOON AND
OVERNIGHT. UPPER LEVEL TROUGH IS CURRENTLY MOVING ACROSS THE FOUR
CORNERS REGION AND LIGHT PRECIPITATION IS DEVELOPING AND REACHING
THE SURFACE ACROSS PORTIONS OF EASTERN COLORADO. EXPECT
SCATTERED PRECIPITATION TO DEVELOP AT KGLD AROUND 20-21Z WITH
DEVELOPMENT AT KMCK A BIT LATER AROUND 22-23Z. ATTM KMCK LOOKS TO
BE THE BETTER RECIPIENT FOR MEASURABLE PRECIP WHICH MAY BRING
VSBY DOWN TO MVFR FOR A FEW HOURS TONIGHT. CIGS STILL REMAIN A
TRICKY FORECAST WITH MODELS BRINGING KMCK DOWN TO IFR AND MAYBE A
BRIEF PERIOD OF LIFR OVERNIGHT. UPPER LEVEL SYSTEM WILL BE EAST OF
THE AREA BY 06-08Z WITH SKIES GRADUALLY CLEARING THROUGH THE END
OF THE PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...BULLER
LONG TERM...JTL
AVIATION...PMM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
448 AM MST FRI DEC 14 2012
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 342 AM MST FRI DEC 14 2012
MAIN FORECAST CONCERN WILL BE STORM SYSTEM THAT WILL IMPACT THE AREA
THROUGH TONIGHT. SATELLITE SHOWING A PROGRESSIVE NEARLY ZONAL FLOW
FROM THE PACIFIC INTO THE WESTERN ATLANTIC. THE EXCEPTION TO THIS
IS THE SYSTEM THAT IS CUT OFF FROM THE FLOW AND EXTENDS FROM NEVADA
TO JUST OFF THE SOUTHERN CALIFORNIA COAST. THROUGH 05Z THIS SYSTEM
WAS STILL DIGGING AND NOT MAKING ANY PROGRESS EAST YET. THIS TROUGH
HAS PULLED UP SUBTROPICAL MOISTURE AHEAD OF IT.
AT JET LEVEL...THE NAM...UKMET AND SREF LOOK TO HAVE THE JET SEGMENT
COMING IN FROM THE SOUTHWEST THE BEST. OTHER MODELS TENDED TO HAVE
THE HIGHER SPEEDS TOO FAR NORTH OR EAST. AT MID LEVELS...WITH THE
INCOMING UPPER TROUGH...MODELS TENDED TO BE TOO FAR SOUTH AND EAST.
THE GFS AND CANADIAN WERE DOING A LITTLE BETTER THAN THE SREF AND
NAM. MODELS ALSO TENDED TO BE TOO GENEROUS WITH THE MID LEVEL
MOISTURE. MODELS ARE HAVING A HARD CATCHING THE SUBTLE COLD FRONT
THAT SAGGED OVER THE AREA TODAY. THE NAM AND RUC WERE DOING THE
BEST. ALSO MODELS ARE TOO GENEROUS WITH LOW LEVEL MOISTURE WITH THE
HIGHER DEWPOINTS TOO FAR NORTH ALREADY. THE GFS AND CANADIAN WERE
DOING THE BEST ON THE LOW LEVEL THERMAL FIELD.
TODAY/TONIGHT...LEFT FRONT QUADRANT OF THE JET CONTINUES TO MOVE
CLOSE TO AREA AND AFFECTS THE AREA MAINLY FROM 12Z TO 18Z. DURING
THAT TIME IT LOOKS LIKE THERE IS NOT A LOT OF LOW LEVEL MOISTURE BUT
LITTLE MOISTURE IN THE COLUMN. SURFACE OBSERVATIONS AND 00Z SOUNDINGS
TO OUR SOUTH ARE VERY DRY. BY THE TIME THE MOISTURE GETS HERE...THE
MAIN JET IS WELL EAST. SPEAKING OF MOISTURE RETURN...DEWPOINTS
REMAIN VERY LOW AND THERE IS NO SIGNIFICANT INCREASE IN MOISTURE
UNTIL WELL SOUTH. MODELS ARE OVERDOING MOISTURE RETURN RIGHT NOW.
00Z SOUNDINGS OVER OUR AREA AND TO THE SOUTH ARE EXTREMELY DRY.
MOISTURE TRAJECTORIES WOULD SUPPORT BEST MOISTURE FURTHER SOUTH AND
EAST. ALSO THUNDERSTORMS WILL BE DEVELOPING TO OUR SOUTH AND EAST
AND SLOW DOWN OR ROB ANY MOISTURE RETURN WE WERE GOING TO SEE.
DUE TO THE SUBTROPICAL MOISTURE RETURN...THERE LOOKS TO BE A
SIGNIFICANT MID/UPPER LEVEL CLOUD DECK WHICH WILL INHIBIT HEATING
AND ANY SURFACE INSTABILITY. MODELS ARE ALSO SHOWING LITTLE TO NO
ELEVATED CAPE AS WELL. WITH MODELS OVERDOING THE INFLUX OF MOISTURE
MODELS ARE PROBABLY OVERDOING ANY INSTABILITY AS WELL. SO CHOSE TO
KEEP THUNDER OUT OF THE FORECAST.
00Z MODEL DATA WAS HINTING AT IT AND NOW 06Z IS CATCHING ONTO IT
EVEN MORE. THE MODELS STILL BRING THE SYSTEM ACROSS IN A NEGATIVE
TILT. HOWEVER...THEY BRING IT ACROSS WITH A NORTHERN AND SOUTHERN
CIRCULATION ON EITHER SIDE OF THE FORECAST AREA. MODELS HAVE BACKED
THEIR IDEA OF ANY WRAP AROUND ON THE BACKSIDE OF THE SYSTEM. PLUS
MODELS HAVE PUSHED EASTERN BAND OF PRECIPITATION FURTHER SOUTH AND
EAST. SO IN A NUTSHELL BEST MOISTURE...LIFT...AND INSTABILITY ARE
NOT INSYNC OR NOT THERE. AT THIS TIME IT STILL DOES LOOK LIKE THE
NORTHEAST PORTION OF THE AREA WILL HAVE THE BEST CHANCE FOR
MEASURABLE PRECIPITATION WITH LITTLE TO NONE FURTHER SOUTHWEST AND
WEST YOU GO.
NEW MODEL GUIDANCE SLOWED THINGS DOWN ON PRECIPITATION ARRIVAL AND
LIMITED POPS TO THE AFTERNOON AND TIERED THEM FROM LOWEST TO HIGHEST
PER REASONING ABOVE. BELIEVE PRECIPITATION WILL SHUT OFF PRETTY QUICK
GIVEN THE SPEED OF THE SYSTEM AND MODEL DEFICIENCIES MENTIONED
ABOVE. BELIEVE MOST OF THE PRECIPITATION WILL BE DOWN BY OR SHORTLY
AFTER 06Z. DID HOLD ONTO PRECIPITATION AFTER THAT JUST KEEP WITHIN
SOME CLOSENESS WITH MY NEIGHBORS. IN REGARDS TO PHASE. LOOKS LIKE IT
STAYS RAIN THROUGH THE DAY. MODEL SOUNDINGS INDICATE TEMPERATURES
STAYING ABOVE FREEZING FOR MOST OF THE NIGHT EVEN IF THERE IS ICE IN
THE COLUMN. SOUNDINGS ARE ALSO NOT OPTIMISTIC ABOUT ICE IN THE
COLUMN EITHER. IT ALSO LOOKS BY THE TIME THE AIR MASS GETS COLD
ENOUGH TO SUPPORT SNOW...THE LIFT AND MOISTURE ARE GONE. SO ONLY
HAVE A MIX OF RAIN AND SNOW AT BEST. THEREFORE THERE SHOULD BE
LITTLE TO NO SNOW ACCUMULATION.
PRIOR TO ARRIVAL OF CLOUDS TEMPERATURES HAVE COOLED OFF
DRAMATICALLY THIS MORNING WITH MODELS TOO WARM. COMBINATION OF
UNFAVORABLE WIND FIELD AND INCREASING CLOUD COVER/DEVELOPING
PRECIPITATION WILL KEEP TEMPERATURES FROM WARMING MUCH. BELIEVE THE
GEM WAS CATCHING THE IDEA THE BEST AND I MAY BE TOO WARM.
SATURDAY/SATURDAY NIGHT...TRICKY MAX TEMPERATURE FORECAST. NORTHWEST
WINDS AND SOME SUN EARLY WILL ALLOW FOR TEMPERATURES TO WARM. BUT
NEXT SHORTWAVE TROUGH WILL DRAMATICALLY INCREASE CLOUD COVER IN THE
AFTERNOON. CHOSE TO TOWARD THE COOLER SIDE. FOR THE NIGHT MODELS
STILL PRODUCING QPF. MODELS DIFFER ON WHERE TO PUT IT BUT GENERALLY
FAVOR THE SOUTHWEST. NOT UNREASONABLE FOR PRECIPITATION TO OCCUR
ANYWHERE BUT AM NOT TOTALLY SOLD ON ANYTHING OCCURRING. SO
BROADBRUSHED LOW SLIGHT CHANCE POPS FOR THE ENTIRE AREA.
SUNDAY/SUNDAY NIGHT...AGAIN LIGHT WIND FIELD AND INCREASING CLOUD
COVER WILL CREATE FOR A TRICKY HIGH TEMPERATURE FORECAST. MODELS
INDICATE A COOLER AIR MASS THAN ON SATURDAY. TRENDED COOLER OR
TOWARD COOLER GUIDANCE.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 342 AM MST FRI DEC 14 2012
AN UPPER LEVEL RIDGE WILL MOVE OVER THE AREA THE FIRST PART OF NEXT
WEEK. FOLLOWING THE RIDGE WILL BE A SHORT WAVE TROUGH...WHICH WILL
APPROACH THE AREA WEDNESDAY. AHEAD OF THE TROUGH THERE MAY BE A
CHANCE FOR SOME PRECIPITATION WEDNESDAY AS A COLD FRONT MOVES
THROUGH. AT THIS TIME MODELS DISAGREE WITH THE TIMING OF THE FRONT
BY AS MUCH AS 12 HOURS. IN ADDITION...LIFT ALONG THE FRONT DOES NOT
LOOK STRONG ENOUGH AT THIS POINT TO DEVELOP ANY PRECIPITATION AND
THE ENVIRONMENT MOISTENS BEHIND THE FRONT WHERE THERE IS ALMOST NO
LIFT. IF MODELS COME INTO A BETTER AGREEMENT WITH THE FRONTAL
PASSAGE...AND IF THE LIFT ALONG THE FRONT WILL STRENGTHEN WITH A
BETTER SUPPLY OF MOISTURE...A MENTION OF PRECIPITATION WILL THEN BE
WARRANTED.
TEMPERATURES FOR THE PERIOD WILL WARM THROUGH WEDNESDAY AHEAD OF THE
COLD FRONT...WITH VALUES 10 TO 15 DEGREES ABOVE NORMAL. AFTER THE
COLD FRONT TEMPERATURES RETURN TO NEAR NORMAL VALUES.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 441 AM MST FRI DEC 14 2012
VERY TRICKY TAF FORECAST. DETAILS DIFFER AMONG THE MODEL OUTPUT AS
TO THE ONSET OF PRECIPITATION AND ALSO WHERE/HOW FAST TO BRING IN
LOWER CEILINGS. AT THIS TIME IT DOES LOOK LIKE RAINFALL WILL NOT
DEVELOP UNTIL MID TO LATE AFTERNOON AT BOTH SITES AND THEN CONTINUE
INTO THE MIDDLE OF THE NIGHT. KMCK WILL HAVE THE BEST CHANCE FOR
RAINFALL WITH ONLY A MINOR REDUCTION IN VISIBILITY. FOR
KGLD...MVFR CEILINGS ARE EXPECTED FROM LATE AFTERNOON UNTIL LATE
EVENING. AT THAT TIME...A COLD FRONT WILL MOVE THROUGH AND ALLOW
CEILINGS TO BECOME VFR. FOR KMCK...MVFR CEILINGS WILL LOWER TO
IFR/LIFR BY MID EVENING ALONG WITH MVFR VISIBILITIES IN FOG AND
CONTINUE UNTIL THE ABOVE MENTIONED FRONT MOVES THROUGH. AT THAT
TIME CEILINGS SHOULD BECOME MVFR AS THE FOG LIFTS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...BULLER
LONG TERM...JTL
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
342 AM MST FRI DEC 14 2012
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 342 AM MST FRI DEC 14 2012
MAIN FORECAST CONCERN WILL BE STORM SYSTEM THAT WILL IMPACT THE AREA
THROUGH TONIGHT. SATELLITE SHOWING A PROGRESSIVE NEARLY ZONAL FLOW
FROM THE PACIFIC INTO THE WESTERN ATLANTIC. THE EXCEPTION TO THIS
IS THE SYSTEM THAT IS CUT OFF FROM THE FLOW AND EXTENDS FROM NEVADA
TO JUST OFF THE SOUTHERN CALIFORNIA COAST. THROUGH 05Z THIS SYSTEM
WAS STILL DIGGING AND NOT MAKING ANY PROGRESS EAST YET. THIS TROUGH
HAS PULLED UP SUBTROPICAL MOISTURE AHEAD OF IT.
AT JET LEVEL...THE NAM...UKMET AND SREF LOOK TO HAVE THE JET SEGMENT
COMING IN FROM THE SOUTHWEST THE BEST. OTHER MODELS TENDED TO HAVE
THE HIGHER SPEEDS TOO FAR NORTH OR EAST. AT MID LEVELS...WITH THE
INCOMING UPPER TROUGH...MODELS TENDED TO BE TOO FAR SOUTH AND EAST.
THE GFS AND CANADIAN WERE DOING A LITTLE BETTER THAN THE SREF AND
NAM. MODELS ALSO TENDED TO BE TOO GENEROUS WITH THE MID LEVEL
MOISTURE. MODELS ARE HAVING A HARD CATCHING THE SUBTLE COLD FRONT
THAT SAGGED OVER THE AREA TODAY. THE NAM AND RUC WERE DOING THE
BEST. ALSO MODELS ARE TOO GENEROUS WITH LOW LEVEL MOISTURE WITH THE
HIGHER DEWPOINTS TOO FAR NORTH ALREADY. THE GFS AND CANADIAN WERE
DOING THE BEST ON THE LOW LEVEL THERMAL FIELD.
TODAY/TONIGHT...LEFT FRONT QUADRANT OF THE JET CONTINUES TO MOVE
CLOSE TO AREA AND AFFECTS THE AREA MAINLY FROM 12Z TO 18Z. DURING
THAT TIME IT LOOKS LIKE THERE IS NOT A LOT OF LOW LEVEL MOISTURE BUT
LITTLE MOISTURE IN THE COLUMN. SURFACE OBSERVATIONS AND 00Z SOUNDINGS
TO OUR SOUTH ARE VERY DRY. BY THE TIME THE MOISTURE GETS HERE...THE
MAIN JET IS WELL EAST. SPEAKING OF MOISTURE RETURN...DEWPOINTS
REMAIN VERY LOW AND THERE IS NO SIGNIFICANT INCREASE IN MOISTURE
UNTIL WELL SOUTH. MODELS ARE OVERDOING MOISTURE RETURN RIGHT NOW.
00Z SOUNDINGS OVER OUR AREA AND TO THE SOUTH ARE EXTREMELY DRY.
MOISTURE TRAJECTORIES WOULD SUPPORT BEST MOISTURE FURTHER SOUTH AND
EAST. ALSO THUNDERSTORMS WILL BE DEVELOPING TO OUR SOUTH AND EAST
AND SLOW DOWN OR ROB ANY MOISTURE RETURN WE WERE GOING TO SEE.
DUE TO THE SUBTROPICAL MOISTURE RETURN...THERE LOOKS TO BE A
SIGNIFICANT MID/UPPER LEVEL CLOUD DECK WHICH WILL INHIBIT HEATING
AND ANY SURFACE INSTABILITY. MODELS ARE ALSO SHOWING LITTLE TO NO
ELEVATED CAPE AS WELL. WITH MODELS OVERDOING THE INFLUX OF MOISTURE
MODELS ARE PROBABLY OVERDOING ANY INSTABILITY AS WELL. SO CHOSE TO
KEEP THUNDER OUT OF THE FORECAST.
00Z MODEL DATA WAS HINTING AT IT AND NOW 06Z IS CATCHING ONTO IT
EVEN MORE. THE MODELS STILL BRING THE SYSTEM ACROSS IN A NEGATIVE
TILT. HOWEVER...THEY BRING IT ACROSS WITH A NORTHERN AND SOUTHERN
CIRCULATION ON EITHER SIDE OF THE FORECAST AREA. MODELS HAVE BACKED
THEIR IDEA OF ANY WRAP AROUND ON THE BACKSIDE OF THE SYSTEM. PLUS
MODELS HAVE PUSHED EASTERN BAND OF PRECIPITATION FURTHER SOUTH AND
EAST. SO IN A NUTSHELL BEST MOISTURE...LIFT...AND INSTABILITY ARE
NOT INSYNC OR NOT THERE. AT THIS TIME IT STILL DOES LOOK LIKE THE
NORTHEAST PORTION OF THE AREA WILL HAVE THE BEST CHANCE FOR
MEASURABLE PRECIPITATION WITH LITTLE TO NONE FURTHER SOUTHWEST AND
WEST YOU GO.
NEW MODEL GUIDANCE SLOWED THINGS DOWN ON PRECIPITATION ARRIVAL AND
LIMITED POPS TO THE AFTERNOON AND TIERED THEM FROM LOWEST TO HIGHEST
PER REASONING ABOVE. BELIEVE PRECIPITATION WILL SHUT OFF PRETTY QUICK
GIVEN THE SPEED OF THE SYSTEM AND MODEL DEFICIENCIES MENTIONED
ABOVE. BELIEVE MOST OF THE PRECIPITATION WILL BE DOWN BY OR SHORTLY
AFTER 06Z. DID HOLD ONTO PRECIPITATION AFTER THAT JUST KEEP WITHIN
SOME CLOSENESS WITH MY NEIGHBORS. IN REGARDS TO PHASE. LOOKS LIKE IT
STAYS RAIN THROUGH THE DAY. MODEL SOUNDINGS INDICATE TEMPERATURES
STAYING ABOVE FREEZING FOR MOST OF THE NIGHT EVEN IF THERE IS ICE IN
THE COLUMN. SOUNDINGS ARE ALSO NOT OPTIMISTIC ABOUT ICE IN THE
COLUMN EITHER. IT ALSO LOOKS BY THE TIME THE AIR MASS GETS COLD
ENOUGH TO SUPPORT SNOW...THE LIFT AND MOISTURE ARE GONE. SO ONLY
HAVE A MIX OF RAIN AND SNOW AT BEST. THEREFORE THERE SHOULD BE
LITTLE TO NO SNOW ACCUMULATION.
PRIOR TO ARRIVAL OF CLOUDS TEMPERATURES HAVE COOLED OFF
DRAMATICALLY THIS MORNING WITH MODELS TOO WARM. COMBINATION OF
UNFAVORABLE WIND FIELD AND INCREASING CLOUD COVER/DEVELOPING
PRECIPITATION WILL KEEP TEMPERATURES FROM WARMING MUCH. BELIEVE THE
GEM WAS CATCHING THE IDEA THE BEST AND I MAY BE TOO WARM.
SATURDAY/SATURDAY NIGHT...TRICKY MAX TEMPERATURE FORECAST. NORTHWEST
WINDS AND SOME SUN EARLY WILL ALLOW FOR TEMPERATURES TO WARM. BUT
NEXT SHORTWAVE TROUGH WILL DRAMATICALLY INCREASE CLOUD COVER IN THE
AFTERNOON. CHOSE TO TOWARD THE COOLER SIDE. FOR THE NIGHT MODELS
STILL PRODUCING QPF. MODELS DIFFER ON WHERE TO PUT IT BUT GENERALLY
FAVOR THE SOUTHWEST. NOT UNREASONABLE FOR PRECIPITATION TO OCCUR
ANYWHERE BUT AM NOT TOTALLY SOLD ON ANYTHING OCCURRING. SO
BROADBRUSHED LOW SLIGHT CHANCE POPS FOR THE ENTIRE AREA.
SUNDAY/SUNDAY NIGHT...AGAIN LIGHT WIND FIELD AND INCREASING CLOUD
COVER WILL CREATE FOR A TRICKY HIGH TEMPERATURE FORECAST. MODELS
INDICATE A COOLER AIR MASS THAN ON SATURDAY. TRENDED COOLER OR
TOWARD COOLER GUIDANCE.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 342 AM MST FRI DEC 14 2012
AN UPPER LEVEL RIDGE WILL MOVE OVER THE AREA THE FIRST PART OF NEXT
WEEK. FOLLOWING THE RIDGE WILL BE A SHORT WAVE TROUGH...WHICH WILL
APPROACH THE AREA WEDNESDAY. AHEAD OF THE TROUGH THERE MAY BE A
CHANCE FOR SOME PRECIPITATION WEDNESDAY AS A COLD FRONT MOVES
THROUGH. AT THIS TIME MODELS DISAGREE WITH THE TIMING OF THE FRONT
BY AS MUCH AS 12 HOURS. IN ADDITION...LIFT ALONG THE FRONT DOES NOT
LOOK STRONG ENOUGH AT THIS POINT TO DEVELOP ANY PRECIPITATION AND
THE ENVIRONMENT MOISTENS BEHIND THE FRONT WHERE THERE IS ALMOST NO
LIFT. IF MODELS COME INTO A BETTER AGREEMENT WITH THE FRONTAL
PASSAGE...AND IF THE LIFT ALONG THE FRONT WILL STRENGTHEN WITH A
BETTER SUPPLY OF MOISTURE...A MENTION OF PRECIPITATION WILL THEN BE
WARRANTED.
TEMPERATURES FOR THE PERIOD WILL WARM THROUGH WEDNESDAY AHEAD OF THE
COLD FRONT...WITH VALUES 10 TO 15 DEGREES ABOVE NORMAL. AFTER THE
COLD FRONT TEMPERATURES RETURN TO NEAR NORMAL VALUES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1000 PM MST THU DEC 13 2012
VFR THROUGH AT LEAST 21Z WITH MVFR/IFR CIGS EXPECTED AFTER 21Z AND
CONTINUING THROUGH THE REST OF THE TAF PERIOD. CIGS WILL QUICKLY
LOWER FRIDAY AFTERNOON...FIRST AT KGLD FOLLOWED SHORTLY BY KMCK AS
A LOW PRESSURE SYSTEM MOVES TOWARD THE AREA FROM THE SOUTHWEST.
A 3 OR SO HOUR PERIOD OF LIGHT RAIN WILL FALL AT KGLD BETWEEN 21
AND 00Z WHILE AT KMCK 22Z-01Z WITHIN AN AREA OF ENHANCED MOISTURE
ROTATING AHEAD OF THE UPPER LOW. ALTHOUGH THE PRECIP ENDS AT BOTH
TERMINALS BY 01Z OR SO PLENTY OF LOW LEVEL MOISTURE REMAINS ACROSS
THE AREA PREVENTING CIGS RISING INTO VFR RANGE. WINDS WILL REMAIN
GENERALLY LIGHT TONIGHT THEN BECOME SOUTHEAST OR SOUTHERLY DURING
THE DAY FRIDAY AROUND 12KTS. AT KGLD A SHIFT TO THE W/NW EXPECTED
AROUND 04Z ON THE BACKSIDE OF THE DEPARTING SYSTEM.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...BULLER
LONG TERM...JTL
AVIATION...DDT
AREA FORECAST DISCUSSION
NWS CARIBOU ME
1235 PM EST FRI DEC 14 2012
.SYNOPSIS...
WEAK LOW PRESSURE WILL PASS NORTH OF THE AREA THIS MORNING WITH A
COLD FRONTAL PASSAGE LATER TODAY AND TONIGHT. HIGH PRESSURE BUILDS
NORTH OF THE REGION SATURDAY.&&
.NEAR TERM /THROUGH TONIGHT/...
1235 PM UPDATE...SNOW SHOWERS HAVE DEVELOPED AT KFVE AND THE VSBY
RAPIDLY DROPPED TO 3/4 OF A MILE. SNOW SHOWERS WILL MOVE OFF TO
THE SOUTHEAST THIS AFTERNOON WITH LOCAL ACCUMULATIONS OF UP TO AN
INCH. A SPECIAL WEATHER STATEMENT WAS ISSUED EARLIER FOR THE SNOW
SHOWERS. UPDATED THE POP/QPF/SNOWFALL GRIDS FOR THE REMAINDER OF
THE AFTERNOON TO BETTER LINE UP WITH LATEST RADAR TRENDS.
907 AM UPDATE...THE MAIN UPDATE WAS TO LOWER THE CLOUD COVER A
BIT DOWN TOWARD THE COAST AS SAT PICTS...OBS...AND WEB CAMS
INDICATE P/SUNNY TO M/SUNNY CONDITIONS. ALSO MADE SOME TWEAKS TO
THE WIND GUST GRIDS ACROSS THE COASTAL WATERS TO HOLD OFF WIND
GUSTS TO 25 KT UNTIL THE START TIME OF THE SCA AT 21Z.
OTHERWISE...THE FORECAST LOOKS TO BE IN GOOD SHAPE. STILL EXPECT
SNOW SHOWERS TO DEVELOP ACROSS THE NORTH THIS PM AS A STRONG
ARCTIC COLD FRONT BEGINS TO WORK ACROSS THE AREA.
UPDATE 0625 EST: HAVE ADJUSTED TEMPERATURE...WEATHER AND POPS.
LOW PRESSURE IS CURRENTLY PASSING TO THE NORTH OF THE STATE. A
STRONG COLD FRONT TRAILING THE LOW WILL APPROACH FROM THE WEST
THIS MORNING THE MOVE ACROSS THE STATE DURING THE AFTERNOON.
STRONG COLD ADVECTION BEHIND THE FRONT ALONG WITH AN UPPER TROUGH
WILL RESULT IN UNSTABLE CONDITIONS RESULTING IN SNOW SQUALLS
ESPECIALLY IN THE NORTH DURING THE AFTERNOON INTO THE EVENING.
WILL USE THE RUC13 TO INITIALIZE THE POP GRIDS THROUGH THE MORNING
THEN TRANSITION TO A BLEND OF THE NAM12 ...GFS40 ...SREF AND
ECMWF. FOR QPF WILL ALSO USE SAME MODEL BLEND AND EXCHANGE THE
NAM12 FOR NAM80. FOR SNOW AMOUNTS WILL RUN SNOW FROM THICKNESS
TOOL ON NAM/QPF GRIDS. THE GMOS WAS USED TO INITIALIZE THE
TEMPERATURE AND DEW POINT GRIDS. HAVE MANUALLY ADJUSTED MAXIMUM
AND MINIMUM TEMPERATURES. USED A NAM12/GMOS BLEND FOR WIND SPEED.
FOR WIND GUSTS WILL USE 200 PERCENT OF SUSTAINED SPEED WITH GOOD
MIXING EXPECTED.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
COLDER WEATHER IN STORE FOR THE WEEKEND.
ARCTIC AIR WILL CONTINUE TO PUSH INTO THE CWA ON SATURDAY W/NNW
WINDS ADDING A CHILL TO THE AIR. THIS WILL MEAN SATURDAY`S HIGHS
WILL BE BELOW NORMAL FOR THE IDES OF DECEMBER. A COLD NNW FLOW OFF
THE OPEN ST. LAWRENCE WILL LEAD TO CLOUDS ACROSS NORTHERN 1/2 OF
THE CWA W/SOME FLURRIES OR BANDS OF LIGHT SNOW THROUGH SATURDAY
AFTERNOON. THE NAM AND GFS TEND TO STRUGGLE W/THSI TYPE OF SETUP.
THE CANADIAN GEM LOOKS LIKE IT PICKS UP ON THIS WELL AND DECIDED
TO USE IT TO SET UP THE FORECAST FOR SATURDAY INTO SATURDAY NIGHT.
SKIES WILL GRADUALLY CLEAR ACROSS THE NORTHERN AREAS SATURDAY
NIGHT AS THE FLOW WEAKENS WHILE THE CENTRAL AND DOWNEAST REGION
REMAIN CLEAR. ALL THIS ALLOWING FOR SOME COLD TEMPERATURES BY
EARLY SUNDAY MORNING. STAYED CLOSE TO THE DAYCREW`S ASSESSMENT OF
READINGS AOB 0F ACROSS THE NORTH AND WEST AND IN THE SINGLE
NUMBERS FOR THE CENTRAL AND DOWNEAST REGIONS.
HIGH PRES WILL MOVE ACROSS NORTHERN QUEBEC AND RIDGE DOWN ACROSS
THE REGION ON SUNDAY. AT THE SAME TIME, LOW PRES MOVING ACROSS THE
GREAT LAKES REGION IS FCST TO RE-DEVELOP OFF THE NJ COAST BY
SUNDAY NIGHT. ATTM, DECIDED TO KEEP THE CWA DRY BANKING ON THE
STRONG HIGH TO THE NORTH HOLDING ON LONGER. THIS MATCHES UP WELL
THE LATEST RUNS OF THE NAM/GFS AND ECMWF. WE WILL SEE INCREASING
CLOUDS FROM THE SW DURING THE DAY W/A GRADUAL MODERATION IN
TEMPERATURES BUT STILL BELOW NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THINGS BEGIN TO GET COMPLICATED ESPECIALLY WEDNESDAY INTO
THURSDAY. DETAILS ARE BELOW.
THE 00Z RUNS OF THE ECMWF/OPERATIONAL GFS AND ITS MEAN ENSEMBLE
SUPPORT LOW PRES REDEVELOPING NEAR NJ SUNDAY NIGHT AND THEN SLOWLY
MOVING ENE OFF THE LONG ISLAND COAST. THE GFS IS MOST PROMINENT
W/THIS FEATURE WHILE THE ECWMF AND THE CANADIAN GLOBAL KEEP THE
SYSTEM LESS AMPLIFIED AND SHOW THE HIGH PRES RIDGE HOLDING ON
LONGER KEEPING THE BULK OF THE PRECIP FURTHER S. DECIDED TO BLEND
THE ECMWF AND GFS FOR THIS SYSTEM SUNDAY NIGHT INTO MONDAY. THIS MEANS
CHC POPS SUNDAY NIGHT FOR THE INTERIOR DOWNEAST AND COAST WHICH
MATCHES UP WELL W/GYX AND STAYED DRY FURTHER NORTH GIVEN THE
RIDGE HOLDING IN LONGER.
THE CHALLENGE NOW COMES FOR MONDAY RIGHT INTO LATE WEEK. THE
ECMWF DOES SHOW A MORE SIGNIFICANT LOW MOVING ACROSS THE DELMARVA
ON MONDAY AND LIFTING THROUGH THE GULF OF MAINE LATER TUESDAY INTO
WEDNESDAY AND THEN WEAKENS THIS LOW W/YET ANOTHER LOW FURTHER TO
THE E TAKING OVER BY THURSDAY AND ENDING THE PRECIP SOONER. THIS
WOULD MEAN SIGNIFICANT A SNOWFALL FOR THE CWA TUESDAY INTO WEDNESDAY
W/DRIER CONDITIONS ON THURSDAY. THE OPERATIONAL GFS HAS THIS LOW
DEVELOPING OFF THE MID ATLC COAST AND LIFTING NORTHWARD AND
INTENSIFYING W/POSSIBLE BLIZZARD CONDITIONS WEDNESDAY INTO
THURSDAY. TO ADD TO THE CONFUSION, 7 OUT OF THE 12 GFS ENSEMBLE
MEMBERS KEEP THIS LOW FURTHER S AND E BY THE SAME TIMEFRAME.
DECIDED TO GO W/LIKELY POPS(60-70%) FOR THE INTERIOR DOWNEAST AND
THE COAST FOR MONDAY INTO TUESDAY AND CHC POPS FURTHER NORTH.
TEMPERATURES LOOK COLD ENOUGH FOR SNOW ALL THE WAY TO THE COAST.
CONFIDENCE DROPS OFF WEDNESDAY INTO THURSDAY GIVEN THE
DISCREPANCIES IN THE LONG RANGE GUIDANCE. CONCERN IS THERE THAT
THE BLOCKING PATTERN SETTING UP OVER NORTHERN CANADA COULD LEAD TO
LOW PRES SYSTEMS BEING SHUNTED FURTHER S AND E. THEREFORE, KEPT
CHC POPS FOR THIS TIMEFRAME. THE DAYCREW CAN ASSESS THIS FURTHER
W/LATER MODEL RUNS. ADJUSTED THE GMOS MAXES DOWN WEDNESDAY INTO
THURSDAY BLENDING IN THE ECMWF TEMPERATURES. ALSO CUT BACK ON
WINDS SPEEDS FROM 40-50 MPH GUSTS DOWN TO 35 MPH. WOULD LIKE TO
SEE A BETTER CONSENSUS OF THE GUIDANCE BEFORE SHOOTING THAT HIGH.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
NEAR TERM: BRIEF PERIOD OF MVFR/IFR CONDITIONS POSSIBLE DUE TO
SNOW SHOWERS AND CEILINGS THIS AFTERNOON INTO THIS EVENING...
OTHERWISE VFR CONDITIONS.
SHORT TERM: COULD BE SEEING SOME MVFR CONDITIONS FOR THE NORTHERN
TERMINALS SATURDAY AND THEN CONDITIONS LOOK LIKE THEY WILL GO VFR
THROUGH SUNDAY. THE CHALLENGE COMES MONDAY INTO TUESDAY W/A POSSIBLE
STORM SYSTEM BRINGING SNOW AND POSSIBLE ICING W/MVFR TO IFR.
&&
.MARINE...
NEAR TERM: HAVE USED A BLEND OF THE NAM12 AND GFS40 TO INITIALIZE
THE WINDS. HAVE INCREASED THE WIND SPEED SEVERAL KNOTS LATER
TONIGHT AS COLDER AIR MOVES ACROSS THE WATERS. FOR WAVES: EXPECT
SOUTHWEST FETCH TO DEVELOP ACROSS THE GULF OF MAINE THIS AFTERNOON
IN TIGHT GRADIENT AHEAD OF APPROACHING FRONT. PRIMARY WAVE GROUP
BUILDING TO 5-6 FEET/6 SECONDS. SECONDARY LONG PERIOD WAVE GROUP
FROM SOUTHEAST. WILL MOVE STARTING TIME FOR SCA TO 2100Z.
SHORT TERM: SCA CONDITIONS MAY NEED TO BE EXTENDED THROUGH
SATURDAY AFTERNOON AS NW WINDS COULD GUST TO 25 KTS W/CAA OVER THE
WATERS ESPECIALLY THE OUTER ZONES. USE A NAM12/GFS BLEND FOR THE
SUSTAINED WINDS SHOWING 15-20 KTS W/GUSTS HITTING 25 KTS ON
SATURDAY. WINDS DROP OFF SATURDAY NIGHT RIGHT THROUGH SUNDAY TO
10-15 KTS. SEAS WILL REMAIN 3-5 FT AT BEST FOR THIS TIME PERIOD.
WINDS/SEAS COULD INCREASE SIGNIFICANTLY MONDAY NIGHT INTO TUESDAY
AS A LOW PRES SYSTEM APCHS FORM THE S. ENE WINDS COULD HIT SCA OR
EVEN GALES. DECIDED TO BACK AWAY FROM THE GMOS ATTM AND CUT BACK
THOSE SPEEDS BY 10 KTS. THIS MEANS SUSTAINED WINDS OF 20-25 KTS
AND GUSTS UP TO 35 KTS. INCREASED THE SEAS UP TO 8-10 FT BY TUESDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 4 PM EST
SATURDAY FOR ANZ050>052.
&&
$$
NEAR TERM...CB/MIGNONE
SHORT TERM...HEWITT
LONG TERM...HEWITT
AVIATION...CB/MIGNONE
MARINE...CB/MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS CARIBOU ME
907 AM EST FRI DEC 14 2012
.SYNOPSIS...
WEAK LOW PRESSURE WILL PASS NORTH OF THE AREA THIS MORNING WITH A
COLD FRONTAL PASSAGE LATER TODAY AND TONIGHT. HIGH PRESSURE BUILDS
NORTH OF THE REGION SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
907 AM UPDATE...THE MAIN UPDATE WAS TO LOWER THE CLOUD COVER A
BIT DOWN TOWARD THE COAST AS SAT PICTS...OBS...AND WEB CAMS
INDICATE P/SUNNY TO M/SUNNY CONDITIONS. ALSO MADE SOME TWEAKS TO
THE WIND GUST GRIDS ACROSS THE COASTAL WATERS TO HOLD OFF WIND
GUSTS TO 25 KT UNTIL THE START TIME OF THE SCA AT 21Z.
OTHERWISE...THE FORECAST LOOKS TO BE IN GOOD SHAPE. STILL EXPECT
SNOW SHOWERS TO DEVELOP ACROSS THE NORTH THIS PM AS A STRONG
ARCTIC COLD FRONT BEGINS TO WORK ACROSS THE AREA.
UPDATE 0625 EST: HAVE ADJUSTED TEMPERATURE...WEATHER AND POPS.
LOW PRESSURE IS CURRENTLY PASSING TO THE NORTH OF THE STATE. A
STRONG COLD FRONT TRAILING THE LOW WILL APPROACH FROM THE WEST
THIS MORNING THE MOVE ACROSS THE STATE DURING THE AFTERNOON.
STRONG COLD ADVECTION BEHIND THE FRONT ALONG WITH AN UPPER TROUGH
WILL RESULT IN UNSTABLE CONDITIONS RESULTING IN SNOW SQUALLS
ESPECIALLY IN THE NORTH DURING THE AFTERNOON INTO THE EVENING.
WILL USE THE RUC13 TO INITIALIZE THE POP GRIDS THROUGH THE MORNING
THEN TRANSITION TO A BLEND OF THE NAM12 ...GFS40 ...SREF AND
ECMWF. FOR QPF WILL ALSO USE SAME MODEL BLEND AND EXCHANGE THE
NAM12 FOR NAM80. FOR SNOW AMOUNTS WILL RUN SNOW FROM THICKNESS
TOOL ON NAM/QPF GRIDS. THE GMOS WAS USED TO INITIALIZE THE
TEMPERATURE AND DEW POINT GRIDS. HAVE MANUALLY ADJUSTED MAXIMUM
AND MINIMUM TEMPERATURES. USED A NAM12/GMOS BLEND FOR WIND SPEED.
FOR WIND GUSTS WILL USE 200 PERCENT OF SUSTAINED SPEED WITH GOOD
MIXING EXPECTED.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
COLDER WEATHER IN STORE FOR THE WEEKEND.
ARCTIC AIR WILL CONTINUE TO PUSH INTO THE CWA ON SATURDAY W/NNW
WINDS ADDING A CHILL TO THE AIR. THIS WILL MEAN SATURDAY`S HIGHS
WILL BE BELOW NORMAL FOR THE IDES OF DECEMBER. A COLD NNW FLOW OFF
THE OPEN ST. LAWRENCE WILL LEAD TO CLOUDS ACROSS NORTHERN 1/2 OF
THE CWA W/SOME FLURRIES OR BANDS OF LIGHT SNOW THROUGH SATURDAY
AFTERNOON. THE NAM AND GFS TEND TO STRUGGLE W/THSI TYPE OF SETUP.
THE CANADIAN GEM LOOKS LIKE IT PICKS UP ON THIS WELL AND DECIDED
TO USE IT TO SET UP THE FORECAST FOR SATURDAY INTO SATURDAY NIGHT.
SKIES WILL GRADUALLY CLEAR ACROSS THE NORTHERN AREAS SATURDAY
NIGHT AS THE FLOW WEAKENS WHILE THE CENTRAL AND DOWNEAST REGION
REMAIN CLEAR. ALL THIS ALLOWING FOR SOME COLD TEMPERATURES BY
EARLY SUNDAY MORNING. STAYED CLOSE TO THE DAYCREW`S ASSESSMENT OF
READINGS AOB 0F ACROSS THE NORTH AND WEST AND IN THE SINGLE
NUMBERS FOR THE CENTRAL AND DOWNEAST REGIONS.
HIGH PRES WILL MOVE ACROSS NORTHERN QUEBEC AND RIDGE DOWN ACROSS
THE REGION ON SUNDAY. AT THE SAME TIME, LOW PRES MOVING ACROSS THE
GREAT LAKES REGION IS FCST TO RE-DEVELOP OFF THE NJ COAST BY
SUNDAY NIGHT. ATTM, DECIDED TO KEEP THE CWA DRY BANKING ON THE
STRONG HIGH TO THE NORTH HOLDING ON LONGER. THIS MATCHES UP WELL
THE LATEST RUNS OF THE NAM/GFS AND ECMWF. WE WILL SEE INCREASING
CLOUDS FROM THE SW DURING THE DAY W/A GRADUAL MODERATION IN
TEMPERATURES BUT STILL BELOW NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THINGS BEGIN TO GET COMPLICATED ESPECIALLY WEDNESDAY INTO
THURSDAY. DETAILS ARE BELOW.
THE 00Z RUNS OF THE ECMWF/OPERATIONAL GFS AND ITS MEAN ENSEMBLE
SUPPORT LOW PRES REDEVELOPING NEAR NJ SUNDAY NIGHT AND THEN SLOWLY
MOVING ENE OFF THE LONG ISLAND COAST. THE GFS IS MOST PROMINENT
W/THIS FEATURE WHILE THE ECWMF AND THE CANADIAN GLOBAL KEEP THE
SYSTEM LESS AMPLIFIED AND SHOW THE HIGH PRES RIDGE HOLDING ON
LONGER KEEPING THE BULK OF THE PRECIP FURTHER S. DECIDED TO BLEND
THE ECMWF AND GFS FOR THIS SYSTEM SUNDAY NIGHT INTO MONDAY. THIS MEANS
CHC POPS SUNDAY NIGHT FOR THE INTERIOR DOWNEAST AND COAST WHICH
MATCHES UP WELL W/GYX AND STAYED DRY FURTHER NORTH GIVEN THE
RIDGE HOLDING IN LONGER.
THE CHALLENGE NOW COMES FOR MONDAY RIGHT INTO LATE WEEK. THE
ECMWF DOES SHOW A MORE SIGNIFICANT LOW MOVING ACROSS THE DELMARVA
ON MONDAY AND LIFTING THROUGH THE GULF OF MAINE LATER TUESDAY INTO
WEDNESDAY AND THEN WEAKENS THIS LOW W/YET ANOTHER LOW FURTHER TO
THE E TAKING OVER BY THURSDAY AND ENDING THE PRECIP SOONER. THIS
WOULD MEAN SIGNIFICANT A SNOWFALL FOR THE CWA TUESDAY INTO WEDNESDAY
W/DRIER CONDITIONS ON THURSDAY. THE OPERATIONAL GFS HAS THIS LOW
DEVELOPING OFF THE MID ATLC COAST AND LIFTING NORTHWARD AND
INTENSIFYING W/POSSIBLE BLIZZARD CONDITIONS WEDNESDAY INTO
THURSDAY. TO ADD TO THE CONFUSION, 7 OUT OF THE 12 GFS ENSEMBLE
MEMBERS KEEP THIS LOW FURTHER S AND E BY THE SAME TIMEFRAME.
DECIDED TO GO W/LIKELY POPS(60-70%) FOR THE INTERIOR DOWNEAST AND
THE COAST FOR MONDAY INTO TUESDAY AND CHC POPS FURTHER NORTH.
TEMPERATURES LOOK COLD ENOUGH FOR SNOW ALL THE WAY TO THE COAST.
CONFIDENCE DROPS OFF WEDNESDAY INTO THURSDAY GIVEN THE
DISCREPANCIES IN THE LONG RANGE GUIDANCE. CONCERN IS THERE THAT
THE BLOCKING PATTERN SETTING UP OVER NORTHERN CANADA COULD LEAD TO
LOW PRES SYSTEMS BEING SHUNTED FURTHER S AND E. THEREFORE, KEPT
CHC POPS FOR THIS TIMEFRAME. THE DAYCREW CAN ASSESS THIS FURTHER
W/LATER MODEL RUNS. ADJUSTED THE GMOS MAXES DOWN WEDNESDAY INTO
THURSDAY BLENDING IN THE ECMWF TEMPERATURES. ALSO CUT BACK ON
WINDS SPEEDS FROM 40-50 MPH GUSTS DOWN TO 35 MPH. WOULD LIKE TO
SEE A BETTER CONSENSUS OF THE GUIDANCE BEFORE SHOOTING THAT HIGH.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: BRIEF PERIOD OF MVFR/IFR CONDITIONS POSSIBLE DUE TO
SNOW SHOWERS AND CEILINGS THIS AFTERNOON INTO THIS EVENING...
OTHERWISE VFR CONDITIONS.
SHORT TERM: COULD BE SEEING SOME MVFR CONDITIONS FOR THE NORTHERN
TERMINALS SATURDAY AND THEN CONDITIONS LOOK LIKE THEY WILL GO VFR
THROUGH SUNDAY. THE CHALLENGE COMES MONDAY INTO TUESDAY W/A POSSIBLE
STORM SYSTEM BRINGING SNOW AND POSSIBLE ICING W/MVFR TO IFR.
&&
.MARINE...
NEAR TERM: HAVE USED A BLEND OF THE NAM12 AND GFS40 TO INITIALIZE
THE WINDS. HAVE INCREASED THE WIND SPEED SEVERAL KNOTS LATER
TONIGHT AS COLDER AIR MOVES ACROSS THE WATERS. FOR WAVES: EXPECT
SOUTHWEST FETCH TO DEVELOP ACROSS THE GULF OF MAINE THIS AFTERNOON
IN TIGHT GRADIENT AHEAD OF APPROACHING FRONT. PRIMARY WAVE GROUP
BUILDING TO 5-6 FEET/6 SECONDS. SECONDARY LONG PERIOD WAVE GROUP
FROM SOUTHEAST. WILL MOVE STARTING TIME FOR SCA TO 2100Z.
SHORT TERM: SCA CONDITIONS MAY NEED TO BE EXTENDED THROUGH
SATURDAY AFTERNOON AS NW WINDS COULD GUST TO 25 KTS W/CAA OVER THE
WATERS ESPECIALLY THE OUTER ZONES. USE A NAM12/GFS BLEND FOR THE
SUSTAINED WINDS SHOWING 15-20 KTS W/GUSTS HITTING 25 KTS ON
SATURDAY. WINDS DROP OFF SATURDAY NIGHT RIGHT THROUGH SUNDAY TO
10-15 KTS. SEAS WILL REMAIN 3-5 FT AT BEST FOR THIS TIME PERIOD.
WINDS/SEAS COULD INCREASE SIGNIFICANTLY MONDAY NIGHT INTO TUESDAY
AS A LOW PRES SYSTEM APCHS FORM THE S. ENE WINDS COULD HIT SCA OR
EVEN GALES. DECIDED TO BACK AWAY FROM THE GMOS ATTM AND CUT BACK
THOSE SPEEDS BY 10 KTS. THIS MEANS SUSTAINED WINDS OF 20-25 KTS
AND GUSTS UP TO 35 KTS. INCREASED THE SEAS UP TO 8-10 FT BY TUESDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST
SATURDAY FOR ANZ050>052.
&&
$$
NEAR TERM...CB/MIGNONE
SHORT TERM...HEWITT
LONG TERM...HEWITT
AVIATION...CB/MIGNONE
MARINE...MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS CARIBOU ME
626 AM EST FRI DEC 14 2012
.SYNOPSIS...
WEAK LOW PRESSURE WILL PASS NORTH OF THE AREA THIS MORNING WITH A
COLD FRONTAL PASSAGE LATER TODAY AND TONIGHT. HIGH PRESSURE BUILDS
NORTH OF THE REGION SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE 0625 EST: HAVE ADJUSTED TEMPERATURE...WEATHER AND POPS.
LOW PRESSURE IS CURRENTLY PASSING TO THE NORTH OF THE STATE. A
STRONG COLD FRONT TRAILING THE LOW WILL APPROACH FROM THE WEST
THIS MORNING THE MOVE ACROSS THE STATE DURING THE AFTERNOON.
STRONG COLD ADVECTION BEHIND THE FRONT ALONG WITH AN UPPER TROUGH
WILL RESULT IN UNSTABLE CONDITIONS RESULTING IN SNOW SQUALLS
ESPECIALLY IN THE NORTH DURING THE AFTERNOON INTO THE EVENING.
WILL USE THE RUC13 TO INITIALIZE THE POP GRIDS THROUGH THE MORNING
THEN TRANSITION TO A BLEND OF THE NAM12 ...GFS40 ...SREF AND
ECMWF. FOR QPF WILL ALSO USE SAME MODEL BLEND AND EXCHANGE THE
NAM12 FOR NAM80. FOR SNOW AMOUNTS WILL RUN SNOW FROM THICKNESS
TOOL ON NAM/QPF GRIDS. THE GMOS WAS USED TO INITIALIZE THE
TEMPERATURE AND DEW POINT GRIDS. HAVE MANUALLY ADJUSTED MAXIMUM
AND MINIMUM TEMPERATURES. USED A NAM12/GMOS BLEND FOR WIND SPEED.
FOR WIND GUSTS WILL USE 200 PERCENT OF SUSTAINED SPEED WITH GOOD
MIXING EXPECTED.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
COLDER WEATHER IN STORE FOR THE WEEKEND.
ARCTIC AIR WILL CONTINUE TO PUSH INTO THE CWA ON SATURDAY W/NNW
WINDS ADDING A CHILL TO THE AIR. THIS WILL MEAN SATURDAY`S HIGHS
WILL BE BELOW NORMAL FOR THE IDES OF DECEMBER. A COLD NNW FLOW OFF
THE OPEN ST. LAWRENCE WILL LEAD TO CLOUDS ACROSS NORTHERN 1/2 OF
THE CWA W/SOME FLURRIES OR BANDS OF LIGHT SNOW THROUGH SATURDAY
AFTERNOON. THE NAM AND GFS TEND TO STRUGGLE W/THSI TYPE OF SETUP.
THE CANADIAN GEM LOOKS LIKE IT PICKS UP ON THIS WELL AND DECIDED
TO USE IT TO SET UP THE FORECAST FOR SATURDAY INTO SATURDAY NIGHT.
SKIES WILL GRADUALLY CLEAR ACROSS THE NORTHERN AREAS SATURDAY
NIGHT AS THE FLOW WEAKENS WHILE THE CENTRAL AND DOWNEAST REGION
REMAIN CLEAR. ALL THIS ALLOWING FOR SOME COLD TEMPERATURES BY
EARLY SUNDAY MORNING. STAYED CLOSE TO THE DAYCREW`S ASSESSMENT OF
READINGS AOB 0F ACROSS THE NORTH AND WEST AND IN THE SINGLE
NUMBERS FOR THE CENTRAL AND DOWNEAST REGIONS.
HIGH PRES WILL MOVE ACROSS NORTHERN QUEBEC AND RIDGE DOWN ACROSS
THE REGION ON SUNDAY. AT THE SAME TIME, LOW PRES MOVING ACROSS THE
GREAT LAKES REGION IS FCST TO RE-DEVELOP OFF THE NJ COAST BY
SUNDAY NIGHT. ATTM, DECIDED TO KEEP THE CWA DRY BANKING ON THE
STRONG HIGH TO THE NORTH HOLDING ON LONGER. THIS MATCHES UP WELL
THE LATEST RUNS OF THE NAM/GFS AND ECMWF. WE WILL SEE INCREASING
CLOUDS FROM THE SW DURING THE DAY W/A GRADUAL MODERATION IN
TEMPERATURES BUT STILL BELOW NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THINGS BEGIN TO GET COMPLICATED ESPECIALLY WEDNESDAY INTO
THURSDAY. DETAILS ARE BELOW.
THE 00Z RUNS OF THE ECMWF/OPERATIONAL GFS AND ITS MEAN ENSEMBLE
SUPPORT LOW PRES REDEVELOPING NEAR NJ SUNDAY NIGHT AND THEN SLOWLY
MOVING ENE OFF THE LONG ISLAND COAST. THE GFS IS MOST PROMINENT
W/THIS FEATURE WHILE THE ECWMF AND THE CANADIAN GLOBAL KEEP THE
SYSTEM LESS AMPLIFIED AND SHOW THE HIGH PRES RIDGE HOLDING ON
LONGER KEEPING THE BULK OF THE PRECIP FURTHER S. DECIDED TO BLEND
THE ECMWF AND GFS FOR THIS SYSTEM SUNDAY NIGHT INTO MONDAY. THIS MEANS
CHC POPS SUNDAY NIGHT FOR THE INTERIOR DOWNEAST AND COAST WHICH
MATCHES UP WELL W/GYX AND STAYED DRY FURTHER NORTH GIVEN THE
RIDGE HOLDING IN LONGER.
THE CHALLENGE NOW COMES FOR MONDAY RIGHT INTO LATE WEEK. THE
ECMWF DOES SHOW A MORE SIGNIFICANT LOW MOVING ACROSS THE DELMARVA
ON MONDAY AND LIFTING THROUGH THE GULF OF MAINE LATER TUESDAY INTO
WEDNESDAY AND THEN WEAKENS THIS LOW W/YET ANOTHER LOW FURTHER TO
THE E TAKING OVER BY THURSDAY AND ENDING THE PRECIP SOONER. THIS
WOULD MEAN SIGNIFICANT A SNOWFALL FOR THE CWA TUESDAY INTO WEDNESDAY
W/DRIER CONDITIONS ON THURSDAY. THE OPERATIONAL GFS HAS THIS LOW
DEVELOPING OFF THE MID ATLC COAST AND LIFTING NORTHWARD AND
INTENSIFYING W/POSSIBLE BLIZZARD CONDITIONS WEDNESDAY INTO
THURSDAY. TO ADD TO THE CONFUSION, 7 OUT OF THE 12 GFS ENSEMBLE
MEMBERS KEEP THIS LOW FURTHER S AND E BY THE SAME TIMEFRAME.
DECIDED TO GO W/LIKELY POPS(60-70%) FOR THE INTERIOR DOWNEAST AND
THE COAST FOR MONDAY INTO TUESDAY AND CHC POPS FURTHER NORTH.
TEMPERATURES LOOK COLD ENOUGH FOR SNOW ALL THE WAY TO THE COAST.
CONFIDENCE DROPS OFF WEDNESDAY INTO THURSDAY GIVEN THE
DISCREPANCIES IN THE LONG RANGE GUIDANCE. CONCERN IS THERE THAT
THE BLOCKING PATTERN SETTING UP OVER NORTHERN CANADA COULD LEAD TO
LOW PRES SYSTEMS BEING SHUNTED FURTHER S AND E. THEREFORE, KEPT
CHC POPS FOR THIS TIMEFRAME. THE DAYCREW CAN ASSESS THIS FURTHER
W/LATER MODEL RUNS. ADJUSTED THE GMOS MAXES DOWN WEDNESDAY INTO
THURSDAY BLENDING IN THE ECMWF TEMPERATURES. ALSO CUT BACK ON
WINDS SPEEDS FROM 40-50 MPH GUSTS DOWN TO 35 MPH. WOULD LIKE TO
SEE A BETTER CONSENSUS OF THE GUIDANCE BEFORE SHOOTING THAT HIGH.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: BRIEF PERIOD OF MVFR/IFR CONDITIONS POSSIBLE DUE TO
SNOW SHOWERS AND CEILINGS ...OTHERWISE VFR CONDITIONS.
SHORT TERM: COULD BE SEEING SOME MVFR CONDITIONS FOR THE NORTHERN
TERMINALS SATURDAY AND THEN CONDITIONS LOOK LIKE THEY WILL GO VFR
THROUGH SUNDAY. THE CHALLENGE COMES MONDAY INTO TUESDAY W/A POSSIBLE
STORM SYSTEM BRINGING SNOW AND POSSIBLE ICING W/MVFR TO IFR.
&&
.MARINE...
NEAR TERM: HAVE USED A BLEND OF THE NAM12 AND GFS40 TO INITIALIZE
THE WINDS. HAVE INCREASED THE WIND SPEED SEVERAL KNOTS LATER
TONIGHT AS COLDER AIR MOVES ACROSS THE WATERS. FOR WAVES: EXPECT
SOUTHWEST FETCH TO DEVELOP ACROSS THE GULF OF MAINE THIS AFTERNOON
IN TIGHT GRADIENT AHEAD OF APPROACHING FRONT. PRIMARY WAVE GROUP
BUILDING TO 5-6 FEET/6 SECONDS. SECONDARY LONG PERIOD WAVE GROUP
FROM SOUTHEAST. WILL MOVE STARTING TIME FOR SCA TO 2100Z.
SHORT TERM: SCA CONDITIONS MAY NEED TO BE EXTENDED THROUGH
SATURDAY AFTERNOON AS NW WINDS COULD GUST TO 25 KTS W/CAA OVER THE
WATERS ESPECIALLY THE OUTER ZONES. USE A NAM12/GFS BLEND FOR THE
SUSTAINED WINDS SHOWING 15-20 KTS W/GUSTS HITTING 25 KTS ON
SATURDAY. WINDS DROP OFF SATURDAY NIGHT RIGHT THROUGH SUNDAY TO
10-15 KTS. SEAS WILL REMAIN 3-5 FT AT BEST FOR THIS TIME PERIOD.
WINDS/SEAS COULD INCREASE SIGNIFICANTLY MONDAY NIGHT INTO TUESDAY
AS A LOW PRES SYSTEM APCHS FORM THE S. ENE WINDS COULD HIT SCA OR
EVEN GALES. DECIDED TO BACK AWAY FROM THE GMOS ATTM AND CUT BACK
THOSE SPEEDS BY 10 KTS. THIS MEANS SUSTAINED WINDS OF 20-25 KTS
AND GUSTS UP TO 35 KTS. INCREASED THE SEAS UP TO 8-10 FT BY TUESDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST
SATURDAY FOR ANZ050>052.
&&
$$
NEAR TERM...MIGNONE
SHORT TERM...HEWITT
LONG TERM...HEWITT
AVIATION...MIGNONE
MARINE...MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS CARIBOU ME
405 AM EST FRI DEC 14 2012
.SYNOPSIS...
WEAK LOW PRESSURE WILL PASS NORTH OF THE AREA THIS MORNING WITH A
COLD FRONTAL PASSAGE LATER TODAY AND TONIGHT. HIGH PRESSURE BUILDS
NORTH OF THE REGION SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOW PRESSURE IS CURRENTLY PASSING TO THE NORTH OF THE STATE. A
STRONG COLD FRONT TRAILING THE LOW WILL APPROACH FROM THE WEST
THIS MORNING THE MOVE ACROSS THE STATE DURING THE AFTERNOON.
STRONG COLD ADVECTION BEHIND THE FRONT ALONG WITH AN UPPER TROUGH
WILL RESULT IN UNSTABLE CONDITIONS RESULTING IN SNOW SQUALLS
...ESPECIALLY IN THE NORTH DURING THE AFTERNOON INTO THE EVENING.
WILL USE THE RUC13 TO INITIALIZE THE POP GRIDS THROUGH THE MORNING
THEN TRANSITION TO A BLEND OF THE NAM12 ...GFS40 ...SREF AND
ECMWF. FOR QPF WILL ALSO USE SAME MODEL BLEND AND EXCHANGE THE
NAM12 FOR NAM80. FOR SNOW AMOUNTS WILL RUN SNOW FROM THICKNESS
TOOL ON NAM/QPF GRIDS. THE GMOS WAS USED TO INITIALIZE THE
TEMPERATURE AND DEW POINT GRIDS. HAVE MANUALLY ADJUSTED MAXIMUM
AND MINIMUM TEMPERATURES. USED A NAM12/GMOS BLEND FOR WIND SPEED.
FOR WIND GUSTS WILL USE 200 PERCENT OF SUSTAINED SPEED WITH GOOD
MIXING EXPECTED.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
COLDER WEATHER IN STORE FOR THE WEEKEND.
ARCTIC AIR WILL CONTINUE TO PUSH INTO THE CWA ON SATURDAY W/NNW
WINDS ADDING A CHILL TO THE AIR. THIS WILL MEAN SATURDAY`S HIGHS
WILL BE BELOW NORMAL FOR THE IDES OF DECEMBER. A COLD NNW FLOW OFF
THE OPEN ST. LAWRENCE WILL LEAD TO CLOUDS ACROSS NORTHERN 1/2 OF
THE CWA W/SOME FLURRIES OR BANDS OF LIGHT SNOW THROUGH SATURDAY
AFTERNOON. THE NAM AND GFS TEND TO STRUGGLE W/THSI TYPE OF SETUP.
THE CANADIAN GEM LOOKS LIKE IT PICKS UP ON THIS WELL AND DECIDED
TO USE IT TO SET UP THE FORECAST FOR SATURDAY INTO SATURDAY NIGHT.
SKIES WILL GRADUALLY CLEAR ACROSS THE NORTHERN AREAS SATURDAY
NIGHT AS THE FLOW WEAKENS WHILE THE CENTRAL AND DOWNEAST REGION
REMAIN CLEAR. ALL THIS ALLOWING FOR SOME COLD TEMPERATURES BY
EARLY SUNDAY MORNING. STAYED CLOSE TO THE DAYCREW`S ASSESSMENT OF
READINGS AOB 0F ACROSS THE NORTH AND WEST AND IN THE SINGLE
NUMBERS FOR THE CENTRAL AND DOWNEAST REGIONS.
HIGH PRES WILL MOVE ACROSS NORTHERN QUEBEC AND RIDGE DOWN ACROSS
THE REGION ON SUNDAY. AT THE SAME TIME, LOW PRES MOVING ACROSS THE
GREAT LAKES REGION IS FCST TO RE-DEVELOP OFF THE NJ COAST BY
SUNDAY NIGHT. ATTM, DECIDED TO KEEP THE CWA DRY BANKING ON THE
STRONG HIGH TO THE NORTH HOLDING ON LONGER. THIS MATCHES UP WELL
THE LATEST RUNS OF THE NAM/GFS AND ECMWF. WE WILL SEE INCREASING
CLOUDS FROM THE SW DURING THE DAY W/A GRADUAL MODERATION IN
TEMPERATURES BUT STILL BELOW NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THINGS BEGIN TO GET COMPLICATED ESPECIALLY WEDNESDAY INTO
THURSDAY. DETAILS ARE BELOW.
THE 00Z RUNS OF THE ECMWF/OPERATIONAL GFS AND ITS MEAN ENSEMBLE
SUPPORT LOW PRES REDEVELOPING NEAR NJ SUNDAY NIGHT AND THEN SLOWLY
MOVING ENE OFF THE LONG ISLAND COAST. THE GFS IS MOST PROMINENT
W/THIS FEATURE WHILE THE ECWMF AND THE CANADIAN GLOBAL KEEP THE
SYSTEM LESS AMPLIFIED AND SHOW THE HIGH PRES RIDGE HOLDING ON
LONGER KEEPING THE BULK OF THE PRECIP FURTHER S. DECIDED TO BLEND
THE ECMWF AND GFS FOR THIS SYSTEM SUNDAY NIGHT INTO MONDAY. THIS MEANS
CHC POPS SUNDAY NIGHT FOR THE INTERIOR DOWNEAST AND COAST WHICH
MATCHES UP WELL W/GYX AND STAYED DRY FURTHER NORTH GIVEN THE
RIDGE HOLDING IN LONGER.
THE CHALLENGE NOW COMES FOR MONDAY RIGHT INTO LATE WEEK. THE
ECMWF DOES SHOW A MORE SIGNIFICANT LOW MOVING ACROSS THE DELMARVA
ON MONDAY AND LIFTING THROUGH THE GULF OF MAINE LATER TUESDAY INTO
WEDNESDAY AND THEN WEAKENS THIS LOW W/YET ANOTHER LOW FURTHER TO
THE E TAKING OVER BY THURSDAY AND ENDING THE PRECIP SOONER. THIS
WOULD MEAN SIGNIFICANT A SNOWFALL FOR THE CWA TUESDAY INTO WEDNESDAY
W/DRIER CONDITIONS ON THURSDAY. THE OPERATIONAL GFS HAS THIS LOW
DEVELOPING OFF THE MID ATLC COAST AND LIFTING NORTHWARD AND
INTENSIFYING W/POSSIBLE BLIZZARD CONDITIONS WEDNESDAY INTO
THURSDAY. TO ADD TO THE CONFUSION, 7 OUT OF THE 12 GFS ENSEMBLE
MEMBERS KEEP THIS LOW FURTHER S AND E BY THE SAME TIMEFRAME.
DECIDED TO GO W/LIKELY POPS(60-70%) FOR THE INTERIOR DOWNEAST AND
THE COAST FOR MONDAY INTO TUESDAY AND CHC POPS FURTHER NORTH.
TEMPERATURES LOOK COLD ENOUGH FOR SNOW ALL THE WAY TO THE COAST.
CONFIDENCE DROPS OFF WEDNESDAY INTO THURSDAY GIVEN THE
DISCREPANCIES IN THE LONG RANGE GUIDANCE. CONCERN IS THERE THAT
THE BLOCKING PATTERN SETTING UP OVER NORTHERN CANADA COULD LEAD TO
LOW PRES SYSTEMS BEING SHUNTED FURTHER S AND E. THEREFORE, KEPT
CHC POPS FOR THIS TIMEFRAME. THE DAYCREW CAN ASSESS THIS FURTHER
W/LATER MODEL RUNS. ADJUSTED THE GMOS MAXES DOWN WEDNESDAY INTO
THURSDAY BLENDING IN THE ECMWF TEMPERATURES. ALSO CUT BACK ON
WINDS SPEEDS FROM 40-50 MPH GUSTS DOWN TO 35 MPH. WOULD LIKE TO
SEE A BETTER CONSENSUS OF THE GUIDANCE BEFORE SHOOTING THAT HIGH.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: BRIEF PERIOD OF MVFR/IFR CONDITIONS POSSIBLE DUE TO
SNOW SHOWERS AND CEILINGS ...OTHERWISE VFR CONDITIONS.
SHORT TERM: COULD BE SEEING SOME MVFR CONDITIONS FOR THE NORTHERN
TERMINALS SATURDAY AND THEN CONDITIONS LOOK LIKE THEY WILL GO VFR
THROUGH SUNDAY. THE CHALLENGE COMES MONDAY INTO TUESDAY W/A POSSIBLE
STORM SYSTEM BRINGING SNOW AND POSSIBLE ICING W/MVFR TO IFR.
&&
.MARINE...
NEAR TERM: HAVE USED A BLEND OF THE NAM12 AND GFS40 TO INITIALIZE
THE WINDS. HAVE INCREASED THE WIND SPEED SEVERAL KNOTS LATER
TONIGHT AS COLDER AIR MOVES ACROSS THE WATERS. FOR WAVES: EXPECT
SOUTHWEST FETCH TO DEVELOP ACROSS THE GULF OF MAINE THIS AFTERNOON
IN TIGHT GRADIENT AHEAD OF APPROACHING FRONT. PRIMARY WAVE GROUP
BUILDING TO 5-6 FEET/6 SECONDS. SECONDARY LONG PERIOD WAVE GROUP
FROM SOUTHEAST. WILL MOVE STARTING TIME FOR SCA TO 2100Z.
SHORT TERM: SCA CONDITIONS MAY NEED TO BE EXTENDED THROUGH
SATURDAY AFTERNOON AS NW WINDS COULD GUST TO 25 KTS W/CAA OVER THE
WATERS ESPECIALLY THE OUTER ZONES. USE A NAM12/GFS BLEND FOR THE
SUSTAINED WINDS SHOWING 15-20 KTS W/GUSTS HITTING 25 KTS ON
SATURDAY. WINDS DROP OFF SATURDAY NIGHT RIGHT THROUGH SUNDAY TO
10-15 KTS. SEAS WILL REMAIN 3-5 FT AT BEST FOR THIS TIME PERIOD.
WINDS/SEAS COULD INCREASE SIGNIFICANTLY MONDAY NIGHT INTO TUESDAY
AS A LOW PRES SYSTEM APCHS FORM THE S. ENE WINDS COULD HIT SCA OR
EVEN GALES. DECIDED TO BACK AWAY FROM THE GMOS ATTM AND CUT BACK
THOSE SPEEDS BY 10 KTS. THIS MEANS SUSTAINED WINDS OF 20-25 KTS
AND GUSTS UP TO 35 KTS. INCREASED THE SEAS UP TO 8-10 FT BY TUESDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST
SATURDAY FOR ANZ050>052.
&&
$$
NEAR TERM...MIGNONE
SHORT TERM...HEWITT
LONG TERM...HEWITT
AVIATION...MIGNONE
MARINE...MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1012 PM EST SAT DEC 15 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE FROM PLAINS STATES INTO THE GREAT LAKES
REGION TONIGHT THROUGH SUNDAY...PUSHING A WARM FRONT THROUGH THE
AREA. ANOTHER AREA OF LOW PRESSURE MOVES FROM THE OHIO VALLEY TO
THE NORTHEASTERN STATES MONDAY...WITH THE TRAILING COLD FRONT
CROSSING THE REGION EARLY TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
CURRENT GOES WATER VAPOR IMAGERY SHOWS A BROAD PLUME OF MID/UPPER
LEVEL MOISTURE EXTENDING FROM THE SUBTROPICAL EAST PACIFIC ACROSS
TX AND INTO THE TENNESSEE VALLEY...WITH CLOSED UPPER LOWS OVER THE
FOUR CORNERS REGION AND GREAT LAKES. THE GREAT LAKES LOW IS
TRIGGERING RADAR RETURNS ACROSS THE NORTHERN MID ATLANTIC.
HOWEVER...THE 00Z KLWX SOUNDING SHOWED VERY DRY AIR BELOW
600MB...SO THESE RADAR RETURNS ARE MAINLY MANIFESTED IN AN 8-12K
FT MID-CLOUD LAYER. THIS CLOUD LAYER IS SUB-FREEZING...SO VIRGA
FALLING INTO THE MILDER AIR BELOW IS LIKELY MELTING AND CAUSING
THE ECHOES TO APPEAR MUCH MORE SUBSTANTIAL THAN REALITY...HENCE
ONLY SPRINKLES WILL BE INCLUDED THROUGH MIDNIGHT FOR THE CENTRAL
VA PIEDMONT COUNTIES THROUGH THE LOWER MD EASTERN SHORE.
MEANWHILE...LONGWAVE IR IMAGERY SHOWS COOLING CLOUD TOPS
INDICATIVE OF AN EMBEDDED IMPULSE OVER EASTERN TN. THIS WAVE IS
EXPECTED TO INTERACT WITH INCREASING WAA AS A WARM FRONT LIFTS N
ACROSS THE CAROLINA COASTAL PLAIN. THE LATEST RUC PROGS RATHER
STRONG LOW/MID LEVEL LIFT LATE TONIGHT INTO EARLY SUNDAY MORNING
ACROSS SE VA AND NE NC. POPS HAVE BEEN INCREASED TO LIKELY OVER SE
VA/NE NC LATE TONIGHT INTO SUNDAY MORNING...GIVEN THE SATELLITE
TRENDS AND LATEST RUC SOLUTIONS. AT THIS POINT ANTECEDENT DRY
CONDITIONS ARE STILL EXPECTED DELAY THE ONSET OF ANY RAIN...BUT
KRAX AND KAKQ RADARS ARE INDICATING AN INCREASE IN LOW-LEVEL
MOISTURE BY SHOWING LIGHT ECHOES FROM CENTRAL NC TO THE TIDEWATER.
GENERALLY QPF AMOUNTS SHOULD GENERALLY RANGE BETWEEN 0.1-0.2IN
ACROSS EXTREME SE VA AND COASTAL NE NC...BUT THERE IS SOME
INDICATION OF POTENTIAL ELEVATED CONVECTIVE ELEMENTS THAT COULD
RESULT IN UP TO 0.2-0.3IN. OTHERWISE...ONLY SLIGHT CHANCE/CHANCE
POPS ARE FORECAST ELSEWHERE AFTER MIDNIGHT. OVERNIGHT MINIMA ARE
LIKELY OCCURRING THIS EVENING...ESPECIALLY ACROSS THE SE WHERE LOWS
FROM THE MID 30S TO LOW 40S WILL RISE TO THE UPPER 40S TO LOW 50S
BY MORNING. ELSEWHERE...TEMPERATURES SHOULD BE STEADY IN THE LOW
TO MID 40S.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
WARM FRONT LIFTS NORTH ACROSS THE REGION SUNDAY MORNING, WITH A BIT
OF A LULL IN ACCUMULATING PCPN EXPECTED SUN MORN. SHORTWAVE TROUGH
IS PROGGED TO FOLLOW SW FLOW ALOFT, PUSHING ACROSS THE REGION LATER
SUNDAY. THUS, RAIN CHANCES INCREASE AGAIN BY LATE SUNDAY MORNING
INTO EARLY EVENING. CONTINUE TO ORIENT HIGHEST (LIKELY) RAIN CHANCES
ACROSS ROUGHLY ALONG AND NORTH OF I-64, WITH LOWER CHCS FOR RAIN, OR
A FEW SHRAS OVER SE VA AND NE NC. TEMPERATURES FAIRLY MILD AS FA
REMAINS IN WARM SECTOR AHEAD OF APPROACHING COLD FRONT. HIGHS A BIT
OF A CHALLENGE GIVEN CONTINUED SIGNIFICANT CLOUD COVER. LOOKING FOR
M-U50S NORTH TO L-M60S SOUTH.
FIRST SLUG OF MOISTURE/SHORTWAVE KICKS OFF THE DELMARVA COAST SUNDAY
NIGHT. MIDLVL DRY OUT A BIT, WHICH WOULD TEND TO FAVOR SOME PATCHY
DZ/FOG RATHER THAN ACCUMULATING PCPN LATE SUN NIGHT/ERY MONDAY
MORNING. GIVEN ONSHORE FLOW/WAA AND CONSIDERABLE CLOUDINESS, WENT
AOA WARMER MET GUIDANCE. LOWS ~50-55.
MONDAY...
BRIEF LULL IN PCPN MONDAY MORNING AHEAD OF SECOND SHORTWAVE, WHICH
IS EXPECTED TO BEGIN TO CROSS THE LOCAL AREA MIDDAY MONDAY INTO MON
NIGHT. HAVE AGAIN ORIENTED BEST POPS IN THE AFTN/EVE TIME FRAME
MONDAY. DESPITE INCREASINGLY MOIST AIRMASS, QPF VALUES APPEAR RATHER
MEAGER WITH BETTER FORCING ONCE AGAIN OFF TO OUR NORTH (FROM THE OH
VLY INTO THE NORTHEAST) AND TO OUR SOUTH. STILL, QPF OF AN
ADDITIONAL ONE TO TWO-TENTHS ON AVERAGE APPEARS REASONABLE. DESPITE
SHRAS AND CONSIDERABLE CLOUDS, RATHER MILD W/ CONTINUED WAA. LOOK
FOR HIGHS INTO THE U50S-NR 60 ACROSS THE PIEDMONT, L-M60S ELSEWHERE.
MONDAY NIGHT/TUESDAY...
SECOND SHORTWAVE PIVOTS NE/OFFSHORE LATE MON. UPPER LOW
DAMPENS/WEAKENS A BIT AS IT MOVES FROM THE MIDDLE MS VALLEY MON
NIGHT NE TO THE EASTERN GREAT LAKES BY TUESDAY MORNING...PUSHING
THE ATTENDANT SFC FRONT EAST AS WELL. NUMERICAL GUIDANCE HAS
SLOWED SLIGHTLY WITH FRONTAL TIMING. NEW 12Z SUITE OF DATA LOOKS
TO BRING FRONT THROUGH BY/SHORTLY AFTER DAWN TUESDAY MORNING.
GIVEN WEAK FRONTAL FORCING, EXPECT THIS TIMING TO CONTINUE TO SLOW
SLIGHTLY WITH SUBSEQUENT RUNS. THUS, GIVEN THIS SLOWER TIMING AND
WITH SIG CAA LIKELY TO LAG BEHIND FROPA, HV KEPT MAXIMA IN THE
U50S/NR 60 WEST, M-U60S SE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
TRENDED EXTENDED PERIOD FORECAST TOWARD THE LATEST EUROPEAN MODEL,
AS A STORM SYSTEM BRINGS WET CONDITIONS AND COOL TEMPS TO THE MID
ATLANTIC STATES TOWARD THE END OF NEXT WEEK.
UPPER/SFC LOW WILL CONTINUE TO PUSH OFFSHORE WED MORNING AS COOL
MID/UPPER LEVEL TROUGH LOCATES OVER THE INTERMOUNTAIN WEST.
UPPER/SFC HIGH PRESSURE WILL BUILD INTO THE REGION WEDS AS DEEP WLY
FLOW BRINGS SUNNY TO PARTLY SUNNY SKIES. AS THE BEST COLD AIR WILL
REMAIN NORTH OF THE REGION...850 TEMPS ONLY EXPECTED TO FALL TO
RIGHT AROUND FREEZING. THUS...HAVE TRENDED TEMPS WEDS A FEW DEGS
WARMER INTO THE MID/UPPER 50S.
SFC HIGH PRESSURE WILL DRIFT OFF THE SE COAST THURSDAY MORNING AS
THE MID LEVEL RIDGE AXIS MOVES EAST OF THE REGION LATE THURSDAY
MORNING. DEPARTING LOW PRESSURE FROM EARLIER IN THE WEEK WILL PHASE
WITH STRONG LOW OVER THE NORTHERN ATLANTIC...HELPING AMPLIFY THE
EAST COAST RIDGE. THIS WILL RESULT IN INCREASED SWLY FLOW AND
MOISTURE ADVECTION INTO THE REGION. CLOUDS WILL ALSO BE ON THE
INCREASE WITH MOSTLY CLOUDY/CLOUDY SKIES EXPECTED BY THURSDAY
AFTERNOON. WHILE HEIGHTS/THICKNESS VALUES INCREASE...CLOUD COVER AND
WEAK MIXING WILL LIMIT AFTERNOON WARMING WITH TEMPS ONLY EXPECTED IN
THE LOW/MID 50S N TO MID/UPPER 50S S.
WHILE SPATIAL AND TIMING DIFFERENCES EXIST WITH THE COLD FRONT IN
EACH RUN...FRONT IS EXPECTED TO REACH THE FA THURS NIGHT AND CROSS
THE REGION THROUGH FRIDAY MORNING. BEST FORCING FOR ASCENT LOOKS TO
BE OVER THE REGION AS VORT MAX AND PV ANOMALY...AS WELL AS COUPLING
SUBTROPICAL/POLAR JET INCREASE DIVERGENCE ALOFT. COULD SEE A GOOD
CHANCE AT WIDESPREAD BENEFICIAL RAIN SHOWERS. COLD POLAR CONTINENTAL
AIR WILL RUSH IN BEHIND THE SYSTEM WITH TEMPS EXPECTED IN THE MID
40S NE TO MID 50S SW FRIDAY AFTERNOON (TEMPS MAY FALL DURING THE DAY
DEPENDING ON FRONTAL TIMING). TEMPS WILL FALL INTO THE MID/UPPER 20S
SATURDAY MORNING ONLY TO REBOUND INTO THE LOW/MID 40S SATURDAY
AFTERNOON...POSSIBLY COLDER. MOST OF THE PRECIP WILL BE TIED TO THE
FRONT AND BEATING THE POLAR AIR...TEMPS WILL BE WARM ENOUGH TO
SQUASH ANY WINTRY MIX FRIDAY MORNING.
AS OMEGA BLOCKING IS FORECAST TO OCCUR OVER THE NORTHERN ATLANTIC
THROUGH NEXT WEEKEND...COLD WEATHER IS LIKELY TO CONTINUE THROUGH
THE WEEKEND AS ANOTHER SHORTWAVE REINFORCES THE COLD AIR.
HOWEVER...DRY CONDITIONS WILL PREVAIL.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
LOW CONFIDENCE FORECAST FOR SUNDAY AS WARM ADVECTION STRATUS
DEVELOPS OVER THE REGION. USED A MIXTURE OF GUIDANCE WITH NAM
SEEMING TO LOW. EXPECT LOWEST BASES WILL BE OVER NRN AREAS. A FEW
HOURS OF LIGHT RAIN IS EXPECTED THROUGH MID MRNG. KEPT IFR OUT
OF THE FCST AT ORF AND ECG. LOW CLOUDS BASES EXPECTED TO ONLY
IMPROVE A LITTLE DURING THE LATE MRNG AND EARLY AFTN. MOST GUIDANCE
BRINGS IFR BACK TO THE TAF SITES BY LATE AFTN BUT DID NOT INCLUDE IT
THIS FAR OUT.
IN THE SHORT TERM...SINCE PUTTING OUT THE TAF...MVFR VSBYS HAVE
DEVELOPED AT PHF AND ORF AS T/TD SPREAD HAS DECREASED UNDER A THIN
PARTIAL CLOUD COVER. WILL MONITOR BUT DO NOT SEE INDICATION OF
WIDESPREAD IFR AT THIS TIME AS CLOUDS INCREASE ACROSS THE AREA.
OUTLOOK...PERIODS OF IFR ALONG WITH PCPN ARE EXPECTED THROUGH MONDAY
NIGHT. CONDITIONS IMPROVE TUESDAY WITH DRY WEATHER FORECAST THROUGH
WEDNESDAY. A CHANCE FOR SHOWERS RETURNS THURSDAY.
&&
.MARINE...
SFC HIGH PRESSURE HAS ALLOWED FOR CALM WINDS AOB 10 KT OVER THE
WATERS THIS AFTERNOON WITH SEAS GENERALLY 2 TO 3 FT. HIGH PRESSURE
WILL SHIFT OFFSHORE THIS EVENING AS A WEAK COASTAL LOW LIFTS UP
THE SE COAST TONIGHT BRINGING LIGHT RAIN AND S/SE WINDS ALONG THE
COAST. LOW PRESSURE WILL THEN LIFT OUT OF THE MIDWEST
MONDAY...WITH A SECONDARY AREA OF LOW PRESSURE DEVELOPING JUST
NORTH OF THE WATERS MONDAY NIGHT/TUESDAY. WINDS WILL BACK TO THE
S/SW MONDAY AFTERNOON (5 TO 10 KT). WITH HIGH PRESSURE LOCATED
OFFSHORE...THE PRESSURE GRADIENT WILL TIGHTEN ALLOWING FOR
INCREASINGLY SLY WINDS OVER THE WATERS BEGINNING MONDAY EVENING. A
WEAK COLD FRONT WILL CROSS THE WATERS MONDAY NIGHT INTO
TUESDAY...BACKING THE WINDS TO THE W/NW AND ALLOWING FOR STRONGER
CAA ALOFT. SEAS WILL BEGIN TO BUILD 4 TO 5 FT TUESDAY
AFTERNOON...THUS SCA HEADLINES WILL LIKELY BE NEEDED AT LEAST OVER
THE NORTHERN COASTAL ZONES. STRONGEST CAA WILL OCCUR TUESDAY NIGHT
INTO WEDNESDAY...WHICH WILL LEAD TO LIKELY SCA CONDITIONS OVER THE
WATERS.
WINDS/SEAS WILL BEGIN TO SUBSIDE WEDS AFTERNOON AS HIGH PRESSURE
BUILDS IN FROM THE SOUTH. ANOTHER STRONGER LOW PRESSURE SYSTEM
WILL IMPACT THE REGION TOWARD THE END OF NEXT WEEK WITH SCA
CONDITIONS LIKELY.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MAM
NEAR TERM...AJZ/MAM
SHORT TERM...MAM
LONG TERM...MPR/SAM
AVIATION...LSA
MARINE...MAS/SAM
AREA FORECAST DISCUSSION...UPDATED
NWS PITTSBURGH PA
922 PM EST SAT DEC 15 2012
.SYNOPSIS...
A WEAK UPPER LEVEL WAVE WILL BRING THE CHANCE FOR SHOWERS THIS
EVENING...WITH ANOTHER WAVE BRINGING A ON SUNDAY. A LOW PRESSURE
SYSTEM...WILL PROVIDE US WITH SHOWERS MONDAY INTO TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
LINE OF LIGHT SHOWERS MOVING THROUGH...WILL CLEAR THE AREA BY 11PM
OR 12AM. LOWEST LEVELS ARE STILL VERY DRY SO RAIN IS NOT AMOUNTING
TO MUCH WITH MANY LOCATIONS REPORTING JUST DRIZZLE OR SPRINKLES.
ONCE THIS AREA OF SHOWERS MOVES TO THE EAST...EXPECT THE REMAINDER
OF THE NIGHT TO BE DRY.
TWEAKED TEMPERATURES BASED ON RECENT HRRR AND GFS LAMP MODEL
OUTPUT...WHICH SHOW LOWS TONIGHT CAN BE 15 TO 20 DEGREES WARMER
THAN NORMAL AND ALL ABOVE FREEZING.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
EXPECT MILD CONDITIONS ALTHOUGH THERE CONTINUES TO BE UNCERTAINTY
REGARDING THE CHANCES OF SHOWERS SUNDAY INTO EARLY MONDAY.
NAM AND GFS MODEL PROFILES SHOW SOME SHALLOW INSTABILITY BUT LIFT
APPEARS LACKING AS THE INITIAL LOW CENTER WILL BE MOVING EASTWARD
THROUGH SOUTHERN CANADA AND A SECOND LOW CENTER WILL LIKELY NOT
DEVELOP UNTIL SUNDAY NIGHT NEAR ARKANSAS. FOR NOW HAVE MAINTAINED
A LOW CHANCE OF SHOWERS FOR SUNDAY AND SUNDAY NIGHT.
WITH SREF AND NAM MODEL OUTPUT CONTINUING TO SHOW A ROBUST LOW
PRESSURE SYSTEM MOVING NORTHEASTWARD FROM ARKANSAS MONDAY TO NEW
YORK STATE EARLY TUESDAY...SHOWERS WILL BECOME LIKELY LATE MONDAY
INTO DAYTIME TUESDAY.
BLEND OF GFS AND NAM MOS AND SREF SHOW TEMPERATURES WILL REMAIN
PARTICULARLY MILD...NEARLY 15 TO 20 DEGREES WARMER THAN
NORMAL...UNTIL THE LOW PRESSURE CENTER EXITS NORTHEAST PAST NEW
YORK STATE EARLY TUESDAY. THEN WESTERLY WINDS WILL PROVIDE A POST
SYSTEM COOL DOWN...ALTHOUGH CONSENSUS OF MODEL OUTPUT SHOW TEMPERATURES
NOT GOING COLDER THAN FREEZING UNTIL TUESDAY NIGHT. SO HAVE
FORECASTED NO MORE THAN A MIX WITH SNOW SHOWERS LATE TUESDAY
AFTERNOON.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LOW PRESSURE WILL MOVE OFF TO THE EAST TUESDAY NIGHT...WITH
PRECIPITATION DIMINISHING FROM SOUTHWEST TO NORTHEAST. WHILE FLOW
WILL BE FAVORABLE FOR LAKE EFFECT SNOW WEDNESDAY...INVERSION LEVELS
CURRENTLY FORECAST TO TOP OUT BELOW 5 KFT WOULD LIKELY LIMIT SNOW TO
LITTLE MORE THAN FLURRIES.
MEANWHILE...NEXT STORM SYSTEM WILL DEVELOP IN THE PLAINS AND
BEGIN TO AFFECT THE REGION THURSDAY. WITH GOOD AGREEMENT FROM 12Z
GFS/ECMWF AND 00Z NAEFS...HAVE BUMPED UP POPS TO LIKELY THURSDAY
AFTERNOON AND EVENING AS BULK OF PRECIPITATION WILL COME THROUGH
WITH COLD FRONT.
LOW CENTER WILL THEN MEANDER ACROSS THE EASTERN GREAT LAKES ON
FRIDAY. THE LOW WILL PUMP COLD AIR INTO THE AREA ON FRIDAY...AND
TEMPERATURES MAY DECREASE THROUGHOUT THE ENTIRE DAY. COLD AIR AND
ADDITIONAL MOISTURE WILL ALLOW FOR A MUCH BETTER CHANCE OF LAKE
EFFECT/UPSLOPE SNOW SHOWERS FRIDAY AND SATURDAY COMPARED TO THE
MID WEEK STORM.
ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY WILL TUMBLE
BELOW NORMAL FOR FRIDAY AND SATURDAY BEHIND THE COLD FRONT.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
SCATTERED SHOWERS ARE EXPECTED TO CROSS MOST TERMINALS THROUGH THE
NEXT 6 HOURS. DRY AIR AT LOW LEVELS MAY ACTUALLY PREVENT RAIN FROM
REACHING THE GROUND. ALL PORTS WILL REMAIN VFR WITH ONSET OF
PRECIPITATION. AS SHOWERS BEGIN TO MOISTEN UP THE LOW LEVELS UP
NORTH...FKL AND DUJ WILL LIKELY DROP TO MVFR CIGS BEFORE SUNRISE
SUNDAY.
SOUTHEAST WINDS AT 5-10 KTS TONIGHT WILL SLOWLY VEER TO THE SOUTH
THROUGH SUNDAY MORNING.
.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
THERE WILL BE A CHANCE OF SHOWERS SUNDAY NIGHT INTO MONDAY...WITH
MORE WIDESPREAD RAIN/SNOW SHOWERS AND RESTRICTIONS MONDAY NIGHT AND
TUESDAY. RESTRICTIONS MAY REMAIN TUESDAY NIGHT INTO WEDNESDAY NIGHT
WITH SOME PARTIAL CLEARING. ANOTHER LOW PRESSURE SYSTEM WILL BRING
RAIN/SNOW SHOWERS ONCE AGAIN ON THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BILLINGS MT
910 PM MST THU DEC 13 2012
.SHORT TERM...VALID FOR FRI AND SAT...
ONLY MINOR CHANGES WERE MADE TO THE FORECAST FOR TONIGHT...MAINLY
TO ADJUST LOWS TOWARD OBSERVED DEWPOINTS AS OF MID EVENING BECAUSE
WEAK LOW-LEVEL FLOW AND LACK OF ANY REAL AIR MASS CHANGE WILL MAKE
THOSE NUMBERS A GOOD GUIDE. WE THUS LOWERED TEMPERATURES FOR PARTS
OF SOUTH CENTRAL MT...ESPECIALLY IN PLACES LIKE WILSALL AND JUDITH
GAP WHERE A COUPLE INCHES OF FRESH SNOW SHOULD LET THEM RADIATE TO
AROUND 10 F OVERNIGHT. IN CONTRAST...WE ACTUALLY RAISED LOWS A BIT
WHERE FOG AND STRATUS ARE IN PLACE...MAINLY EAST OF BILLINGS. THAT
FOG WILL BE THE MAIN WEATHER IMPACT TONIGHT AND FRI MORNING. DENSE
FOG WITH VISIBILITY OF ONE QUARTER MILE OR LESS IS LOCKED INTO THE
YELLOWSTONE RIVER VALLEY AND INTERSTATE 94 CORRIDOR...SO OUR DENSE
FOG ADVISORY IS ON TRACK IN THOSE AREAS. FORECAST SOUNDING DATA IS
SUPPORTIVE OF FOG AT MILES CITY THROUGH MOST OF THE NIGHT...THOUGH
WE STILL HAVE SOME CONCERN THAT LOWER SURFACE DEWPOINTS LOCATED TO
THE SOUTH COULD MOVE IN ON LIGHT SOUTHERLY WINDS AND ACTUALLY HELP
THE FOG LIFT OVERNIGHT. THE OTHER QUESTION ON OUR MINDS IS WHETHER
OR NOT THE DENSE FOG WILL EXPAND...ESPECIALLY AROUND BAKER...WHICH
SITS BETWEEN TWO AREAS OF LOW VISIBILITY AS OF 04 UTC. WE CHOSE TO
LEAVE FALLON COUNTY OUT OF THE DENSE FOG ADVISORY AT THIS POINT AS
RECENT TRENDS AT BAKER SUGGEST VISIBILITY MAY LARGELY STAY ABOVE A
MILE THERE...AN IDEA THAT IS SUPPORTED BY RECENT HRRR RUNS AND THE
18 UTC MAV AND 00 UTC MET MOS. SCHULTZ
.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
THE BIG MESSAGE FOR THE EXTENDED IS PERSISTENT SNOW FOR AREA
MOUNTAINS...PARTICULARLY FOR WEST FACING SLOPES OF THE
BEARTOOTH/ABSAROKA MOUNTAINS. PACIFIC MOISTURE WILL FLOW PRETTY
MUCH CONSTANTLY OVER THESE AREAS FOR THE NEXT WEEK. INCREASED
POPS FOR THESE AREAS TO HIGH SCATTERED OR LIKELY THROUGH THE
PERIOD EXCEPT FOR WEDNESDAY NIGHT INTO THURSDAY. EXPECT AN INCH OR
TWO EACH DAY WITH 3 TO 6 INCHES WITH STRONGER WAVES EMBEDDED IN
THE PACIFIC MOISTURE FETCH. THIS COULD ADD UP TO WELL OVER A FOOT
OF NEW SNOW BY WEDNESDAY IN THE COOKE CITY AREA.
SUNDAY INTO MONDAY A NORTHERN STREAM WAVE PUSHES EASTWARD ALONG
THE CANADIAN BORDER. LOOKS LIKE ENOUGH CYCLONIC FLOW OVER THE AREA
TO BRING ISOLATED TO SCATTERED SNOW SHOWERS TO THE LOWER
ELEVATIONS. RIDGE BUILDS MONDAY AFTERNOON DRYING OUT LOWER
ELEVATIONS. ANOTHER ELONGATED PACIFIC TROF MOVES INTO THE ARE LATE
TUESDAY INTO WEDNESDAY FOR ANOTHER SHOT AT LOWER ELEVATION SNOW
SHOWERS. CYCLONIC FLOW OVER THE HUDSON BAY AREA ROTATES SOME
COLDER AIR INTO THE AREA FOR THURSDAY ALONG WITH INCREASED SNOW
CHANCES GOING INTO FRIDAY. ALTHOUGH SYSTEMS ALOFT ARE MOVING
THROUGH THE AREA PRETTY QUICKLY THE SURFACE PATTERN IS RATHER
STAGNANT WITH NOT MUCH WIND TO MOVE AIRMASSES IN OR OUT. AS A
RESULT LOOKING AT TEMPERATURES STAYING MAINLY IN THE 30S THROUGH
THE EXTENDED FOR HIGHS...WITH TEENS AND 20S FOR LOWS. COLDER AIR
LATE IN THE PERIOD COULD PUSH HIGHS INTO THE 20S. CHAMBERS
&&
.AVIATION...
AREAS OF FOG WILL CONTINUE TO IMPACT KMLS AND KBHK THROUGH FRIDAY
MORNING. EXPECT LIFR/VLIFR CONDITIONS. VFR CONDITIONS WILL PREVAIL
ELSEWHERE. ISOLATED SHOWERS WILL DEVELOP IN THE KLVM VICINITY BY
FRIDAY AFTERNOON. BRS
&&
.PRELIMINARY POINT TEMP/POPS...
FRI SAT SUN MON TUE WED THU
-----------------------------------------------------------
BIL 024/041 020/035 020/035 021/033 025/037 021/028 013/029
01/B 12/W 01/B 21/B 11/B 32/J 00/B
LVM 017/040 018/033 024/030 015/029 024/032 017/023 010/027
01/B 22/J 12/J 22/J 22/J 33/J 00/B
HDN 018/039 016/035 015/035 019/034 022/038 020/030 012/030
00/F 11/B 01/B 21/B 11/B 32/J 00/B
MLS 022/035 018/028 013/034 018/032 021/037 021/031 011/028
00/F 01/B 01/B 21/B 11/B 22/J 02/J
4BQ 020/037 017/034 015/035 019/034 021/037 021/032 013/031
00/F 11/B 00/U 21/B 00/B 21/B 02/J
BHK 017/038 014/027 011/031 018/031 019/036 021/030 012/026
00/F 01/B 00/B 21/B 11/B 21/B 02/J
SHR 017/040 017/033 015/034 019/034 021/036 019/028 012/029
00/B 12/J 11/B 21/B 01/B 22/J 00/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...DENSE FOG ADVISORY IN EFFECT UNTIL 11 AM MST FRIDAY FOR ZONES
30>32.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
543 PM CST SAT DEC 15 2012
.AVIATION...
A WEAK STORM SYSTEM WILL AFFECT WESTERN NEBRASKA TONIGHT WITH
BKN100 CEILINGS LOWERING THROUGH MVFR CEILINGS AFTER 16TH06Z.
THERE IS A SLIGHT CHANCE FOR LIGHT SNOW WITH THE SYSTEM BUT SHOULD
REMAIN SOUTH OF INTERSTATE 80 FROM KOGA TO KLBF. CONFIDENCE NOT
HIGH FOR SNOW TOO IMPACT KLBF SO HAVE LEFT OUT OF THE TAF FOR NOW.
CIGS MAY LOWER INTO IFR OVER SOUTHWEST NEBRASKA SUNDAY MORNING BUT
WILL TAKE A CLOSER LOOK WITH 16TH 06Z ISSUANCE.
&&
.PREV DISCUSSION... /ISSUED 356 PM CST SAT DEC 15 2012/
UPDATE...
DISCUSSION...
JUST A QUICK REFRESH ON THE POPS AND QPF ACROSS SWRN NEB. NO REAL
CHANGE BUT QPF PLUMES SUGGEST HIGHER CONFIDENCE FORM KOGA SOUTH
THROUGH KIML SO POPS ARE UP SLIGHTLY AND MEASUREABLE QPF IS FCST A
BIT FARTHER NORTH.
PREV DISCUSSION... /ISSUED 301 PM CST SAT DEC 15 2012/
DISCUSSION...
THE AREA OF WEAK DEFORMATION ACROSS NERN COLO WILL DRIFT EAST
NORTHEAST AND DECAY THIS EVENING. THUS FAR NO SNOW OR RAIN HAS
REACHED THE GROUND DESPITE THE PERSISTENT RADAR RETURNS. LATER
TONIGHT...A SECOND IMPULSE...CURRENTLY ACROSS THE SRN ROCKIES...WILL
LIFT NORTHEAST FORMING A SECOND AREA OF WEAK DEFORMATION WHICH
COULD DRIFT ACROSS SRN NEB AFTER MIDNIGHT PRODUCING LIGHT SNOW.
THE MODELS ARE HAVING A HARD TIME WITH SOME SOLNS SHOWING
DEFORMATION ACROSS THE SAND HILLS AND OTHERS ACROSS SRN NEB.
THE CONSENSUS OF SOLNS SUPPORTS LIGHT SNOW ACROSS SRN NEB. CHANCE
POPS ARE IN PLACE WITH ACCUMULATIONS LESS THAN AN INCH. HPC
SUGGESTED LITTLE OR NO ACCUMULATION ACROSS SWRN NEB. THE ECM
SHOWED 2 INCHES NEAR KOGA...THE GFS SHOWED 5 INCHES NEAR
KIML...THE GEM SHOWED 2 INCHES NEAR KIML AND THE NAM SHOWED AN
INCH ALL OVER THE PLACE. THE RAP HAS BEEN WOBBLING 1 TO 2 INCHES
NORTH AND SOUTH...GENERALLY NEAR OR SOUTH OF INTERSTATE 80.
IT WOULD BE BEST TO WAIT FOR THE RADAR AND SFC OBSERVATIONS TO
LIGHT UP AND THEN GET MORE SPECIFIC WITH POPS AND SNOW AMOUNTS SINCE
THIS IS A FAIRLY COMPACT AREA OF SNOW THE MODELS ARE FORECASTING
TO DEVELOP. THE MODELS ARE SHOWING A WEAK AREA OF ARCTIC HIGH PRESSURE
BUILDING DOWN TONIGHT AND THE PROGRESS OF THAT AIR COULD HAVE A
LOT TO DO WITH THE LOCATION OF THE SNOWFALL. ALSO...THE NAN AND
RUC SHOW RAIN THIS EVENING AHEAD OF THE FRONT..THEN SNOW WHILE THE
GFS IS ALL SNOW.
THIS SYSTEM WILL EXIT THE FCST AREA LATE IN THE DAY SUNDAY MAKING
FOR A COOL DAY AS THE ARCTIC HIGH DRIFTS EAST...LOW PRESSURE
REFORMS ACROSS THE CNTL HIGH PLAINS AND SOUTH WINDS DEVELOP
RECYCLING COLD AIR NORTH.
THE NEXT WEATHER SYSTEM OF INTEREST CROSSES THE FCST AREA TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT. THERE ARE TWO SCENARIOS SHOWN IN THE
MODELS. THE ECM SUGGESTS A MORE SOUTHERLY ROUTE TAKING A LEAD
SHORT WAVE AND DEFORMATION ZONE THROUGH NORTHWEST NEBRASKA
FOLLOWED BY THE MAIN FORCING THROUGH SRN NEB AND KANSAS...MOSTLY
SOUTH AND EAST OF THE FCST AREA. THE GEM AND GFS SUGGEST A MORE
CLASSIC DISTURBANCE CRIS CROSSING THE COLD FRONT PRODUCING LIGHT
SNOW THROUGHOUT THE FCST AREA. THE FCST USED 50 PERCENT OF THE ECM
AND 25 PERCENT OF THE OTHER TWO MODELS. ALL MODELS SHOW WEAK
FRONTOGENESIS ACROSS NW NEB TUESDAY NIGHT. THE ECM QUICKLY DECAYS
THAT FEATURE WHILE THE GEM AND GFS CARRY THAT ACROSS THE FCST
AREA. EITHER WAY...BY THURSDAY MORNING H10-5 THICKNESSES FALL TO
BELOW 520 DM AND H850 TEMPERATURES ARE AROUND MINUS 7C.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...POWER
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
345 PM CST FRI DEC 14 2012
.DISCUSSION...
A POWERHOUSE UPPER LEVEL LOW AND ATTENDANT PACIFIC COLD FRONT ARE
SWEEPING INTO WEST TEXAS THIS AFTERNOON. THE PV15 SFC SUGGESTS
THIS FRONT WILL MOVE RAPID NORTHEAST INTO KS OVERNIGHT. THE LINE
OF STORMS AND CONVECTION SHOULD FOLLOW THE PV15 SFC. NORTH OF THIS
FEATURE AN AREA OF RAIN AND ISOLATED TSTMS ACROSS WRN KS WILL PUSH
INTO WRN AND NCNTL NEB OVERNIGHT. THE RAP13 SUGGESTS A WEAK AREA
OF DEFORMATION SUPPORTING RAIN TONIGHT. QPF AMOUNTS BETWEEN 1/10
AND 1/3 OF AN INCH ARE EXPECTED...MAINLY EAST OF HIGHWAY 83.
THE PTYPE IS VERY PROBLEMATIC AS EVAPORATIVE COOLING WILL COMPETE
WITH WARM AIR ADVECTION. THE RAP SUGGESTS SUB FREEZING TEMPS ALONG
THE WRN AND NRN EDGES OF THE PCPN SHIELD BY MORNING WITH ICONS OF
SNOW AND FREEZING RAIN. H7 TEMPS ARE 0 TO -5C...NOT VERY COLD AND
VERY SLOW FOR SNOW GROWTH. SO WE WILL MONITOR CONDITIONS AND
PERHAPS WINTER WEATHER CONDITIONS WILL DEVELOP TOWARD MORNING.
THE CONVECTION ACROSS KS TONIGHT WILL LIKELY CAUSE THE H7 LOW TO
JOG SOUTHEAST AWAY FROM THE FCST AREA AS INDICATED BY MOST OF THE MODELS.
THIS COULD EASILY CUT OFF THE FORCING FOR RAIN.
THE MODELS SHOW A WEAK CANADIAN HIGH BUILDING DOWN SATURDAY
FOLLOWED BY AN UPPER LEVEL DISTURBANCE DROPPING THRU SWRN NEB LATE
SATURDAY NIGHT WHICH WOULD SUPPORT FLURRIES OR PERHAPS ISOLATED
SNOW SHOWERS. THEREAFTER...MONDAY AND TUESDAY...LOW PRESSURE WILL
FORM ACROSS THE NRN HIGH PLAINS FOLLOWED BY AN ARCTIC FRONT
WEDNESDAY. ALL MODELS SUGGEST SUFFICIENT MOISTURE AND LOW LEVEL
SATURATION FOR A CHANCE OF SNOW OR SNOW SHOWERS. THIS IS TO BE
FOLLOWED BY A SECOND ARCTIC PUSH FRIDAY. BOTH OF THESE HIGH
PRESSURE SYSTEMS WILL MOVE QUICKLY OFF TO THE EAST AS A FAST UPPER
LEVEL FLOW CONTINUES.
&&
.AVIATION...
FOR THE 18Z TAF FORECAST CYCLE. UPPER LEVEL WAVE WILL RAPIDLY
ADVANCE FROM THE DESERT SOUTHWEST INTO THE CENTRAL PLAINS
TODAY/TONIGHT AND DEEPEN A SURFACE LOW OVER THE HIGH PLAINS OF
EASTERN COLORADO. PRECIPITATION IS SHOWN TO SPREAD NORTHEAST FROM
EASTERN COLORADO INTO THE PLAINS LATE THIS AFTERNOON...WITH THE
POTENTIAL OF MIXED PRECIPITATION AT BOTH KLBF AND KVTN AFTER 06Z
TONIGHT. THERE IS STILL SOME CONSIDERABLE SPREAD REGARDING THE TRACK
OF THE SURFACE LOW...AND THE POTENTIAL OF CONVECTION ACROSS THE
SOUTHERN HIGH PLAINS MAY ALLOW FOR A FURTHER SOUTHERN TRACK OF THE
SYSTEM. THUS CONFIDENCE IN THE TAF FORECAST IS LOW...BUT WILL
RETAIN -RASN WITH MVFR /POSSIBLY LOWER/ AT BOTH AREA TERMINAL FOR
THE TIME BEING...ESPECIALLY GIVEN RECENT RADAR TRENDS JUST SOUTH OF
KLBF. SHORT FUSED UPDATES MAY BE NEEDED. ONE LAST NOTE...DOWNWARD
TRANSFER OF MOMENTUM MAY OCCUR UNDER ANY SHOWER/LINE OF SHOWERS. A
BRIEF PERIOD OF WIND GUSTS AT OR ABOVE 20KTS WOULD BE POSSIBLE.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...TALYOR/CDC
AVIATION...JACOBS
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
852 PM CST SAT DEC 15 2012
.DISCUSSION...
OBS INDICATE THE LAST OF ANY SIGNIFICANT SNOW HAS PUSHED EAST OF
THE FORECAST AREA WITH AREAS OF FOG AND VERY LIGHT SNOW STILL
OCCURRING.
SATELLITE SHOWS A LARGE AREA OF LOW CLOUDS SPREADING SOUTHEAST THRU
ERN ND AND NW MN FROM CANADA AND LATEST RAP MODEL STILL SHOWS A
SATURATED 925 MB LAYER OVERSPREAD ALL OF THE FCST AREA OVERNIGHT.
00Z NAM IS TOO DRY AND THUS TOO COLD TONIGHT. ALSO GETTING SOME
PATCHES OF FOG...THOUGH NOT TOO LOW IN VSBY EXCEPT IN A FEW SPOTS.
DID UPDATE TO ADD PATCHY FOG TO ALL AREAS OVERNIGHT. AS FOR
TEMPS...TEMPS IN CLEAR POCKET OVER SE ND INTO THE CNTRL RRV FALLING
OFF BUT TEMPS WARM AS LOW CLOUDS MOVE IN. THUS THINK MOST AREAS HAVE
SEEN THEIR OVERNIGHT LOWS AND WILL RISE A BIT AND STAY STEADY
OVERNIGHT. THUS UPDATED TEMPS OVERNIGHT INTO SUNDAY FOR MOSTLY
MIDDLE TEENS IN ERN ND AND THE RRV AND TEMPS IN THE FAR EASTERN FCST
AREA WILL FALL INTO THE TEENS OVERNIGHT AS COLDER AIR SPREADS IN.
&&
.AVIATION...
EXPECT IFR CIGS TO PREVAIL THRU 18Z AT DVL/GFK/BJI/TVF WITH SOME
LOWER VSBY AT TIMES IN FOG. FARGO AREA WILL SEE LOW CLOUDS ARRIVE
AFTER MIDNIGHT. LOW CLOUDS WITH CIGS UNDER 1000 FT SHOULD ONLY
SLOWLY IMPROVE A BIT SUN AFTN AS MODELS INDICATE PRETTY SATURATED
LOW LEVELS. WINDS WILL BE NORTH AT 5 TO 15 KTS.
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
RIDDLE
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
627 PM CST SAT DEC 15 2012
.DISCUSSION...
OBSERVATIONS SHOWS THE MAJORITY OF THE PRECIPITAION IS NOW LEAVING
THE FCST AREA WITH ONLY LIGHT SNOW OF SIGNIFICANCE FROM CASS
COUNTY MN ACROSS SOUTHEAST HUBBARD INTO WADENA COUNTIES. THUS DROPPED
WINTER WX ADVISORY FOR ALL BUT FAR SOUTHEAST FCST AREA. REPORTS
INDICATED 1-3 INCHES IN THE ADVISORY AREA HIGHEST WADENA TO EAST
OF PARK RAPIDS. EARLIER ROAD CLOSURES DUE TO THE ICE IN BELTRAMI
COUNTY HAVE BEEN LIFTED AND A STATEMENT ISSUED AT REQUEST OF
BELTRAMI EMERGENCY MANAGEMENT.
OTHERWISE ISSUE TONIGHT WILL BE CLOUD TRENDS AND TEMPS. LATEST RAP
MODEL AND 18Z GFS SHOW WIDESPREAD LOW LEVEL MOISTURE SPREADING
OVER THE REGION FROM THE NORTHWEST DURING THE NIGHT AND LIKELY
REMAINING IN PLACE THRU SUNDAY AS 850 MB LAYER DRIES OUT. IFR CIGS
SPREADING INTO DVL BASIN WILL SLOWLY SPREAD SOUTHEAST WHILE IFR
CIGS IN THE FAR EASTERN FCST AREA NOT LIKELY TO LEAVE. THUS MAY
PLAY HAVOC WITH TEMPS AS TEMPS UPSTREAM IN CLOUDS IN MANITOBA ARE
IN THE 15-20 RANGE. IN BETWEEN SYSTEM CLOUDS TO THE EAST AND
INCOMING LOW CLOUDS IS AN AREA OF THIN CIRRUS OR CLEAR SKY FROM
OAKES TO VALLEY CITY TO GRAND FORKS AND TEMPS HERE FALLING OFF
PRETTY GOOD. BUT FROM LATEST RAP MODELS VIA WEB IT SHOWS LOW CIGS
OVERSPREADING GFK JUST PAST 06Z AND REACHING SE ND BY 12Z. THIS
WILL SLOW ANY TEMP FALL.
&&
.AVIATION...
FOR 00Z TAFS...WENT WITH IDEA GIVEN FROM GFS LAMP MODEL AND RAP
MODEL FCST OF LOW LEVEL MOISTURE INDICATING LOW CLOUDS SPREADING
SLOWLY SOUTH-SOUTHEAST INTO THE GFK-FAR AREAS OVERNIGHT AND
HOLDING IFR CIGS IN DVL BASIN AND IN BEMIDJI-PARK RAPIDS THRU THE
NIGHT. MAINTAINED A PESSIMISTIC VIEW OF CLOUDS THRU SUNDAY RISING
THEN INTO LOW END MVFR RANGE. UPSTREAM OBS INDICATE GOOD DEAL OF
CLOUD COVER IN ERN SASK AND MANITOBA WHERE AND LOW LEVEL FLOW
SHOULD TAKE THEM SOUTH.
&&
.PREV DISCUSSION... /ISSUED 237 PM CST SAT DEC 15 2012/
SHORT TERM...
SHARP CONTRAST IN CONDITIONS ACROSS THE FA THIS AFTERNOON WITH THE
LIGHT SNOW IN THE EAST THE MAIN CHALLENGE FOR THE SHORT TERM
FORECAST. MODELS SEEM TO BE IN FAIR AGREEMENT SO WILL USE A BLEND.
TONIGHT...LIGHT SNOW IS FALLING ACROSS THE EASTERN FA NOW
BASICALLY EAST OF A LINE FROM WASKISH TO KDTL TO AROUND THE
WAHPETON BRECKENRIDGE AREA. SOME SITES ARE STILL WARM WITH KFFM
REPORTING 34F SO THERE COULD STILL BE SOME RAIN/FREEZING RAIN IN
SPOTS IN THIS AREA FOR A WHILE YET LATE THIS AFTERNOON. NOT TOO
FAR TO THE WEST OR FROM CAVALIER TO COOPERSTOWN IT IS SUNNY.
RECEIVED A CALL FROM KBJI ABOUT AN HOUR AGO THAT CONDITIONS HAD
IMPROVED THERE FROM THE ICY CONDITIONS EARLIER THIS MORNING SO ALL
ROADS HAD REOPENED. AREA WEB CAMS FROM KBJI TO KPKD TO WADENA SEEM
TO SHOW A COUPLE OF INCHES OF WET SNOW. THE WETNESS OF THE SNOW IS
ALSO LIKELY COMPACTING WHAT HAS FALLEN SO OVERALL AMOUNTS WILL
PROBABLY END UP BEING A LITTLE LESS THAN WHAT WAS EXPECTED.
HOWEVER THERE COULD STILL BE ANOTHER INCH OR SO IN THE EAST EARLY
TONIGHT AND WITH MUCH COLDER TEMPS EXPECTED ROADS WILL PROBABLY
STILL BE A CHALLENGE DESPITE THE PCPN ENDING. SFC HIGH PRESSURE
NOSES INTO PORTIONS OF EASTERN ND TONIGHT BUT IT LOOKS LIKE A
DIRTY HIGH. THERE ARE LOTS OF LOW CLOUDS OVER WESTERN AND NORTH
CENTRAL ND UP INTO SOUTHERN CANADA. SO LOWS TONIGHT WILL BE HIGHLY
DEPENDENT ON CLOUD COVER. ADVISORY FOR THE FAR SOUTH SET TO EXPIRE
AT 00Z SUN WITH THE REST AT 06Z SUN AND WILL NOT CHANGE THAT AT
THIS POINT. WEB CAMS ALONG THE ND/SD BORDER ON I29 LOOK PRETTY
NASTY TOO ALTHOUGH MUCH LESS SNOW HAS FALLEN THERE.
SUN-TUE...WEAK HIGH PRESSURE CONTINUES ACROSS THE AREA INTO SUNDAY
BUT THERE STILL LOOKS TO BE SOME RESIDUAL CLOUD COVER HANGING
AROUND. MAIN CONCERNS FOR THIS PERIOD PROBABLY REVOLVE AROUND THE
NEXT SYSTEM WHICH COULD ARRIVE AS SOON AS MON NIGHT. AMERICAN
MODELS ARE MUCH QUICKER BRINGING IN THE LIGHT SNOW WITH THE GEM
AND ECMWF MUCH SLOWER. PUSHED BACK THE ARRIVAL TIME OF THE LIGHT
SNOW INTO TUE MORE IN LINE WITH THE ECMWF BUT WILL HAVE TO SEE HOW
THIS WORKS OUT WITH LATER MODEL RUNS. AT THIS POINT THIS SYSTEM
DOES NOT LOOK LIKE A BIG SNOW PRODUCER BUT COULD BRING A LITTLE
LIGHT SNOW TO THE AREA.
LONG TERM (TUE NIGHT-SAT)...
GUIDANCE IN GOOD AGREEMENT WITH EARLY PERIOD LONG WAVE TROUGH
EXTENDING FROM MANITOBA THROUGH THE SOUTHERN PLAINS...TAKING
SURFACE SYSTEM ON A TRACK MORE TO THE EAST OF TODAY`S MINNESOTA
STORM. ANY POPS FOR OUR CWA SHOULD REMAIN CLOSE TO INTERNATIONAL
BORDER ASSOCIATED WITH A WEAKER LOW. HIGH AMPLITUDE UPSTREAM RIDGING
WILL FORCE MUCH COLDER CANADIAN AIR TO THE NORTHERN PLAINS THURSDAY
THAT WILL PERSIST INTO THE WEEKEND. LOOKING FOR THE NEAR NORMAL
HIGHS IN THE 20S AT BEGINNING OF PERIOD TO DROP A GOOD 10 TO 15
DEGREES AS THE WEEK ENDS...WITH LOWS EASING BELOW ZERO ACROSS
MAJORITY OF REGION.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR MNZ024-
031-032.
&&
$$
RIDDLE/GODON
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1007 AM CST FRI DEC 14 2012
.DISCUSSION...
MAIN ADJUSTMENTS FOR THIS MORNING WERE TO INCREASE CLOUD COVER IN
THE SOUTHEAST AND ADD IN A FOG MENTION IN THE WEST FOR THE REST
OF THE MORNING. SAT LOOP SHOWS A FAIR AMOUNT OF MID AND HIGH
CLOUDS MOVING INTO THE SOUTHEASTERN CWA THIS MORNING...AND MODELS
HAVE LOW LEVEL RH VALUES INCREASING THROUGHOUT THE DAY. HRRR SHOWS
A FAIR AMOUNT OF CLOUDS MOVING INTO THE EASTERN CWA...ALTHOUGH THE
HOLE IN THE NORTHEAST SHOULD KEEP THAT AREA CLEAR FOR A BIT LONGER
THIS MORNING INTO EARLY AFTERNOON. FURTHER WEST...LOTS OF STRATUS
CONTINUES SO WILL CONTINUE TO KEEP A CLOUDY MENTION THERE. THERE
IS ALSO SOME FOG ALONG THE SLIGHTLY HIGHER TERRAIN AT VALLEY
CITY...COOOPERSTOWN...AND LANGDON. WEB CAMS IN THE WESTERN
COUNTIES SHOW QUITE A BIT OF FOG...ALTHOUGH WIDESPREAD
VISIBILITIES ARE STILL MOSTLY ABOVE 1/4 MILE WITH COOPERSTOWN THE
ONLY ONE SHOWING DENSE. WILL INCLUDE A MENTION OF FOG IN THE
GRIDS...BUT WILL HOLD OFF ON ANY DENSE FOG ADVISORIES UNLESS MORE
STATIONS TAKE A TURN FOR THE WORSE. KEPT HIGHS IN THE 20S ACROSS
MOST OF THE CWA...WITH SOME LOCATIONS APPROACHING 30 IN THE
SOUTHEAST WHERE READINGS ARE ALREADY IN THE 20S THIS MORNING.
&&
.AVIATION...
STRATUS AND A BIT OF FOG WITH IFR TO MVFR CONDITIONS COVER THE
WESTERN THREE TAF SITES...WHILE THE EAST REMAINS VFR FOR THE TIME
BEING. STATIONS ON THE EDGE OF THE STRATUS DECK...KGFK AND KFAR
MAY SEE SOME BRIEF IMPROVEMENT THIS AFTERNOON WHILE KTVF GOES DOWN
AT TIMES. ALL STATIONS WILL GO DOWN TO MVFR OR LOWER AFTER 06Z
TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 350 AM CST FRI DEC 14 2012/
SHORT TERM (TODAY-SUNDAY NIGHT)...CLOUD TRENDS AND PRECIP
CHANCES/TYPE WILL BE THE CHALLENGE. 00Z MODELS INITIALIZED WITH
MINIMAL ERRORS...BUT CONTINUE TO SHOW DIFFERENCES THROUGH THE
PERIOD. THE ECMWF HAS BEEN MOST CONSISTENT RUN TO RUN AND WILL
FOLLOW FOR DETAILS.
UPPER TROUGH IS CRASHING THE SOUTHWEST CONUS AND WILL EJECT INTO
THE CENTRAL PLAINS TONIGHT.
FOR TODAY...SOUTHERLY LOW LEVEL FLOW WILL CONTINUE ALONG WITH WARM
AIR ADVECTION. 06Z RAP INDICATES 925MB WAA STRONGEST ACROSS THE
EASTERN FA...WITH 925MB DEWPOINTS NOT INCREASING MUCH. THIS WOULD
KEEP SKY MOSTLY CLOUDY WEST AND MOSTLY CLEAR EAST. IF THIS SKY
PREDICTION COMES TRUE...TEMPS WOULD LIKELY ONLY RISE A FEW
DEGREES ACROSS THE WEST...AND WOULD APPROACH THE FREEZING MARK
ACROSS THE EAST.
TONIGHT-SATURDAY...MODELS STILL HAVE DIFFERENCES WITH THE SPEED
AND TRACK OF THE MID-LEVEL TROUGH LEADING TO FAIRLY LOW
CONFIDENCE. THIS SYSTEM IS NOT THE STRONGEST...BUT THE GULF
APPEARS OPEN AND PWATS SHOULD BE OVER 0.5 INCH. THE MAIN FORCING
MECHANISM TO AFFECT THIS FA WILL BE DEFORMATION AS A 700MB LOW
TRACKS INTO NORTHERN MINNESOTA. A FEW QUESTIONS STILL
UNCERTAIN...1) HOW QUICKLY WILL HIGHER 925MB MOISTURE SURGE
NORTHWARD...2) P-TYPE AND FZRA POTENTIAL...3) HOW MUCH SNOW. THE
GFS IS THE QUICKEST BRINGING ABOVE 0C DEWPOINTS INTO THE EASTERN
FA TONIGHT. THIS WOULD LEAD TO A PROLONGED DZ/FZDZ SCENARIO BEFORE
DEFORMATION ZONE ARRIVES. ALL OTHER MODELS ARE NOT AS QUICK WITH
THIS MOISTURE SURGE...AND THE PROBABILITY FOR A PROLONGED PERIOD
OF FZDZ APPEARS LOW AT THIS POINT. AS THE MAIN PRECIP SHIED
ARRIVES INTO THE FA...THE 925-850MB LAYER WILL BE ABOVE FREEZING.
HOWEVER...EVAPORATIVE COOLING SHOULD QUICKLY CHANGE LIQUID PRECIP
TO SNOW...AND LIMIT FZRA. DID INSERT A SLIGHT CHANCE FOR FZRA INTO
THE WX GRIDS FOR 09Z-15Z SATURDAY. MODEL QPF SUGGESTS 1-3 INCHES
OF SNOW POSSIBLE ACROSS THE EASTERN FA. THE ABOVE SCENARIO IS WITH
FOLLOWING THE ECMWF...WHICH IS ONE SOLUTION OF MANY...HOPEFULLY
ANOTHER MODEL RUN CAN INCREASE CONFIDENCE WITH THE ABOVE
QUESTIONS.
MODELS APPEAR TO WANT TO KEEP MID-LEVEL CIRCULATION NEAR THE FA ON
SUNDAY...WHICH WOULD LEAD TO MORE CLOUDS AND POSSIBLE FLURRIES.
WILL NEED TO MONITOR THIS TREND IN THE MODELS.
LONG TERM (MONDAY-THURSDAY)...
OVERALL...THERE IS PRETTY GOOD AGREEMENT AMONG THE MODELS WITH
OVERALL SYNOPTIC EVOLUTION OF THE PATTERN DURING THIS PERIOD...WITH
MORE UNCERTAINTY REGARDING THE FORECAST DETAILS. THE PERIOD WILL
BEGIN WITH WEAK SFC HIGH PRESSURE UNDER FAIRLY ZONAL FLOW ALOFT.
TEMPERATURES ON MONDAY AND TUESDAY ARE EXPECTED TO BE WITHIN A FEW
DEGREES OF SEASONAL NORMS. HAVE KEPT THESE DAYS MAINLY
DRY...ALTHOUGH WITH GUIDANCE SHOWING WEAK UPPER WAVES CASCADING
THROUGH THE FLOW...A BIT OF LIGHT SNOW COULD NOT BE RULED OUT.
IT APPEARS THAT A RELATIVELY PROGRESSIVE LONGWAVE TROUGH WILL SHIFT
FROM THE ROCKIES INTO THE PLAINS DURING THE MIDDLE OF NEXT WEEK.
THIS WOULD SUPPORT THE DEVELOPMENT OF A LEE CYCLONE ACROSS COLORADO
LIFTING INTO THE PLAINS. THE 00Z GFS IS MORE PROGRESSIVE AND LESS
AMPLIFIED THAN THE 00Z ECMWF/GEM WITH THIS FEATURE. A MORE AMPLIFIED
SOLUTION SUCH AS THE ECMWF/GEM WOULD SUPPORT STRONGER SFC
CYCLOGENESIS SOMEWHERE ACROSS THE PLAINS. HOWEVER...MODEL SPREAD IS
LARGE AT THIS RANGE...SO CONFIDENCE IN THE EVOLUTION OF THE SYSTEM
IS LOW. TEMPS LOOK TO REMAIN SEASONABLE AHEAD OF THE SYSTEM...WITH
COOLING EXPECTED IN ITS WAKE BACK BELOW NORMAL.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
JR
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
350 AM CST FRI DEC 14 2012
.SHORT TERM (TODAY-SUNDAY NIGHT)...CLOUD TRENDS AND PRECIP
CHANCES/TYPE WILL BE THE CHALLENGE. 00Z MODELS INITIALIZED WITH
MINIMAL ERRORS...BUT CONTINUE TO SHOW DIFFERENCES THROUGH THE
PERIOD. THE ECMWF HAS BEEN MOST CONSISTENT RUN TO RUN AND WILL
FOLLOW FOR DETAILS.
UPPER TROUGH IS CRASHING THE SOUTHWEST CONUS AND WILL EJECT INTO
THE CENTRAL PLAINS TONIGHT.
FOR TODAY...SOUTHERLY LOW LEVEL FLOW WILL CONTINUE ALONG WITH WARM
AIR ADVECTION. 06Z RAP INDICATES 925MB WAA STRONGEST ACROSS THE
EASTERN FA...WITH 925MB DEWPOINTS NOT INCREASING MUCH. THIS WOULD
KEEP SKY MOSTLY CLOUDY WEST AND MOSTLY CLEAR EAST. IF THIS SKY
PREDICTION COMES TRUE...TEMPS WOULD LIKELY ONLY RISE A FEW
DEGREES ACROSS THE WEST...AND WOULD APPROACH THE FREEZING MARK
ACROSS THE EAST.
TONIGHT-SATURDAY...MODELS STILL HAVE DIFFERENCES WITH THE SPEED
AND TRACK OF THE MID-LEVEL TROUGH LEADING TO FAIRLY LOW
CONFIDENCE. THIS SYSTEM IS NOT THE STRONGEST...BUT THE GULF
APPEARS OPEN AND PWATS SHOULD BE OVER 0.5 INCH. THE MAIN FORCING
MECHANISM TO AFFECT THIS FA WILL BE DEFORMATION AS A 700MB LOW
TRACKS INTO NORTHERN MINNESOTA. A FEW QUESTIONS STILL
UNCERTAIN...1) HOW QUICKLY WILL HIGHER 925MB MOISTURE SURGE
NORTHWARD...2) P-TYPE AND FZRA POTENTIAL...3) HOW MUCH SNOW. THE
GFS IS THE QUICKEST BRINGING ABOVE 0C DEWPOINTS INTO THE EASTERN
FA TONIGHT. THIS WOULD LEAD TO A PROLONGED DZ/FZDZ SCENARIO BEFORE
DEFORMATION ZONE ARRIVES. ALL OTHER MODELS ARE NOT AS QUICK WITH
THIS MOISTURE SURGE...AND THE PROBABILITY FOR A PROLONGED PERIOD
OF FZDZ APPEARS LOW AT THIS POINT. AS THE MAIN PRECIP SHIED
ARRIVES INTO THE FA...THE 925-850MB LAYER WILL BE ABOVE FREEZING.
HOWEVER...EVAPORATIVE COOLING SHOULD QUICKLY CHANGE LIQUID PRECIP
TO SNOW...AND LIMIT FZRA. DID INSERT A SLIGHT CHANCE FOR FZRA INTO
THE WX GRIDS FOR 09Z-15Z SATURDAY. MODEL QPF SUGGESTS 1-3 INCHES
OF SNOW POSSIBLE ACROSS THE EASTERN FA. THE ABOVE SCENARIO IS WITH
FOLLOWING THE ECMWF...WHICH IS ONE SOLUTION OF MANY...HOPEFULLY
ANOTHER MODEL RUN CAN INCREASE CONFIDENCE WITH THE ABOVE
QUESTIONS.
MODELS APPEAR TO WANT TO KEEP MID-LEVEL CIRCULATION NEAR THE FA ON
SUNDAY...WHICH WOULD LEAD TO MORE CLOUDS AND POSSIBLE FLURRIES.
WILL NEED TO MONITOR THIS TREND IN THE MODELS.
.LONG TERM (MONDAY-THURSDAY)...
OVERALL...THERE IS PRETTY GOOD AGREEMENT AMONG THE MODELS WITH
OVERALL SYNOPTIC EVOLUTION OF THE PATTERN DURING THIS PERIOD...WITH
MORE UNCERTAINTY REGARDING THE FORECAST DETAILS. THE PERIOD WILL
BEGIN WITH WEAK SFC HIGH PRESSURE UNDER FAIRLY ZONAL FLOW ALOFT.
TEMPERATURES ON MONDAY AND TUESDAY ARE EXPECTED TO BE WITHIN A FEW
DEGREES OF SEASONAL NORMS. HAVE KEPT THESE DAYS MAINLY
DRY...ALTHOUGH WITH GUIDANCE SHOWING WEAK UPPER WAVES CASCADING
THROUGH THE FLOW...A BIT OF LIGHT SNOW COULD NOT BE RULED OUT.
IT APPEARS THAT A RELATIVELY PROGRESSIVE LONGWAVE TROUGH WILL SHIFT
FROM THE ROCKIES INTO THE PLAINS DURING THE MIDDLE OF NEXT WEEK.
THIS WOULD SUPPORT THE DEVELOPMENT OF A LEE CYCLONE ACROSS COLORADO
LIFTING INTO THE PLAINS. THE 00Z GFS IS MORE PROGRESSIVE AND LESS
AMPLIFIED THAN THE 00Z ECMWF/GEM WITH THIS FEATURE. A MORE AMPLIFIED
SOLUTION SUCH AS THE ECMWF/GEM WOULD SUPPORT STRONGER SFC
CYCLOGENESIS SOMEWHERE ACROSS THE PLAINS. HOWEVER...MODEL SPREAD IS
LARGE AT THIS RANGE...SO CONFIDENCE IN THE EVOLUTION OF THE SYSTEM
IS LOW. TEMPS LOOK TO REMAIN SEASONABLE AHEAD OF THE SYSTEM...WITH
COOLING EXPECTED IN ITS WAKE BACK BELOW NORMAL.
&&
.AVIATION...THE GENERAL TREND WILL BE CLEARING FROM SOUTH TO NORTH
ACROSS MINNESOTA...WITH LOW CLOUDS REMAINING ACROSS NORTH DAKOTA.
KGFK WILL BE THE TRICKIEST AS THEY WILL BE ON THE EDGE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
TG/MAKOWSKI
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
936 PM EST SAT DEC 15 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE INTO THE GREAT LAKES THROUGH SUNDAY...WITH
A COLD FRONT MOVING INTO THE OHIO VALLEY THROUGH SUNDAY NIGHT. AN
AREA OF LOW PRESSURE WILL THEN DEVELOP ON MONDAY...WITH ANOTHER
COLD FRONT FOLLOWING ON MONDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
GOING FORECAST PRETTY MUCH ON TARGET RIGHT NOW. UPDATED TO STOP
ANY MORE FALL IN TEMPS...THE WARM SECTOR CONTINUES TO SLOWLY
ESTABLISH ITSELF OVER THE FORECAST AREA...AND WITH THE
THICK/EXPANSIVE/LOWERING STRATUS AND INCREASING SWLY BOUNDARY
LAYER FLOW IT WILL BE TOUGH FOR TEMPS TO DROP FROM CURRENT VALUES.
MAINTAINED THE LOW SHOWER CHANCE TONIGHT - BUT THOUGHT HEAVILY
ABOUT PULLING IT COMPLETELY IN LIEU OF LOW RAIN CHANCES JUST FOR
MEASURABLE DRIZZLE. DEEP MOISTURE /PER EVENING SATELLITE LOOPS AND
16.00Z KILN SOUNDING/ IS ABSENT SO HAVE THE FEELING THE
LIGHT/SPECKLED QPF SEEN ON MANY DETERMINISTIC 15.18Z DATASETS IS
PROBABLY REFLECTION OF THE DRIZZLE THAT HAS BEEN SEEN IN HIT/MISS
FASHION TO OUR WEST. THAT SAID...RADAR ECHO OVER CNTL/NRN IND DOES
HAVE SHOWERY LOOK TO IT AT TIMES SO KEPT MENTION OF BOTH DRIZZLE
AND SHOWERS OVERNIGHT BUT THINK AREAS OF DRIZZLE PROBABLY WIN OUT
IN TERMS OF WHAT/S MORE PREVALENT. IN TERMS OF DRIZZLE...THE
16.00Z NAM AND RECENT 16.XXZ RUNS OF RAP INDICATE THE 0-2KM
RH WILL CONTINUE TO EXPAND/INCREASE THROUGH THE NIGHT SO WE SHOULD
SEE AREAS OF -DZ INCREASE ESP AFTER 06Z. WINDS WILL CONTINUE TO
VEER/SLOWLY INCREASE THROUGH THE NIGHT AS WEAK LOW MEANDERS
THROUGH WISCONSIN AND INTO NRN LOWER MICH.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
THE BASIC PREMISE OF THE SHORT TERM FORECAST HAS COME INTO BETTER
AGREEMENT WITH THE 12Z MODEL CYCLE...BUT MANY OF THE DETAILS
REMAIN SOMEWHAT UNCERTAIN.
AS CLOUDS GRADUALLY LIFT ON SUNDAY MORNING...DRIZZLE IS EXPECTED
TO COME TO AN END. A SLOW MOVING AND ILL-DEFINED FRONT WILL BE
MOVING INTO THE REGION FROM THE NORTH...ASSOCIATED WITH THE GREAT
LAKES SURFACE LOW. THE TIMING OF THIS FEATURE HAS SLOWED...AND
ONLY THE HIGH-RESOLUTION OF THE NAM12 SHOWS AN INDICATION OF THE
FRONT ACTIVATING IN ANY SIGNIFICANT WAY. MARGINAL INSTABILITY WILL
BE ABLE TO BUILD AHEAD OF THE FRONT...BUT THE FORCING IS NOT
PARTICULARLY STRONG. A SLIGHT CHANCE OF THUNDER HAS BEEN
MAINTAINED IN THE SOUTH AND SOUTHEASTERN PORTIONS OF THE FORECAST
AREA.
A SURFACE LOW IS EXPECTED TO DEVELOP NEAR THE OHIO/MISSISSIPPI
RIVER CONFLUENCE BY MONDAY MORNING...AHEAD OF AN ENERGETIC TROUGH
MOVING THROUGH THE MIDDLE OF THE COUNTRY. SUBTRACTING THE NAM
SOLUTION...MODELS SEEM TO BE AGREEING ON A CINCINNATI-TO-ERIE
TRACK FOR THIS LOW...WITH INCREASED CONFIDENCE IN MEASURABLE
PRECIPITATION ACROSS THE FORECAST AREA. A SIGNIFICANT UPWARD
ADJUSTMENT WAS MADE TO BRING THE ENTIRE CWA TO LIKELY POPS ON
MONDAY. THERE IS AN INDICATION OF SOME WEAK INSTABILITY
DEVELOPING...BUT THIS MAINLY SEEMS TO FOLLOW BEHIND THE GREATER
CHANCES OF PRECIPITATION. THUNDER WAS NOT INCLUDED IN THE FORECAST.
THE STRENGTH OF THE MID LEVEL WAVE WILL HAVE AN IMPACT ON HOW LONG
THE PRECIPITATION IS ABLE TO PERSIST ON EARLY TUESDAY MORNING.
TEMPERATURES BEHIND THE LOW (AND ASSOCIATED COLD FRONT) WILL COOL
OFF ENOUGH TO SUPPORT SNOW AT THE END OF THE FORECAST PERIOD...BUT
WITH PRECIPITATION EXPECTED TO BE MOVING OUT...LITTLE MORE THAN A
RAIN/SNOW MIX WITH NO ACCUMULATION CAN BE FORECAST AT THIS TIME.
WITH THE BOUNDARY AND LOW IN THE AREA DURING THIS PART OF THE
FORECAST...TEMPERATURE GRADIENTS ARE A BIT SHARPER THAN NORMAL FOR
BOTH MAXES AND MINS. WITH THIS IN MIND...AND THE WAY THAT ANY
SMALL MODEL DIFFERENCES COULD CHANGE THE TEMPERATURE FORECAST BY
SEVERAL DEGREES...A BLENDED APPROACH NEAR THE MEDIAN OF THE MODEL
SPECTRUM WAS USED.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
ALTHOUGH THE OPERATIONAL MODELS ARE LATCHING ON TO THE MAIN SYNOPTIC
FEATURES IN THE EXTENDED PERIOD...THERE CONTINUES TO BE CONSIDERABLE
SPREAD IN TERMS OF STRENGTH...TIMING AND A PLACEMENT OF THESE
FEATURES. AS A RESULT...HAVE LEANED MORE ON THE 15.12Z ECMWF AND
BLENDED IT WITH HPC GUIDANCE. THE 15.12Z ECMWF WAS USED DUE TO THE
FACT THAT IT TENDS TO PERFORM BETTER THAN THE GFS IN THE EXTENDED
AND OFTEN LATCHES ON TO A PATTERN A DAY AHEAD OF THE GFS.
ON TUESDAY...LOW PRESSURE WILL CONTINUE TO PUSH NE OF THE REGION AS
A WEAK SURFACE RIDGE BUILDS INTO THE OHIO VALLEY. ANY LINGERING PCPN
IN THE EAST WILL COME TO AN END BY AFTERNOON...FOLLOWED BY PARTIAL
CLEARING. TEMPERATURES WILL REMAIN MILD WITH HIGHS MAINLY IN THE 40S.
FOR TUESDAY NIGHT INTO WEDNESDAY...WEAK SURFACE RIDGE WILL MOVE EAST
AS A MID LEVEL RIDGE BUILDS ACRS THE OHIO VALLEY REGION IN ADVANCE
OF THE NEXT WEATHER SYSTEM. MID AND HIGH LEVEL CLOUDINESS CAN BE
EXPECTED ALONG WITH CONTINUE MILD TEMPERATURES. HIGHS ON WEDNESDAY
WILL RANGE FROM THE LOWER 40S NORTH TO THE LOWER 50S SOUTH.
FOR THE PERIOD WEDNESDAY NIGHT INTO FRIDAY...MODELS CONTINUE TO SHOW
A PATTERN CHANGE IN THE OFFING WITH THE UPR LVL FLOW BECOMING MORE
AMPLIFIED THROUGH THE PERIOD. A VIGOROUS S/WV WILL PIVOT FROM THE
SRN PLAINS TO THE GREAT LAKES REGION THROUGH THE PERIOD. THIS UPR
LVL SUPPORT WILL PERTURB DEEPENING LOW PRESSURE WHICH WILL PUSH A
STRONG COLD FRONT THROUGH THE REGION SOMETIME THURSDAY INTO THURSDAY
NIGHT. IT APPEARS THE SFC LOW WILL TRACK NW OF THE REGION WHICH
WOULD KEEP HEAVIER WINTER PCPN TO THE NW OF THE TRACK AND OUT OF OUR
AREA. DEEP MOISTURE RETURN AND DYNAMICS WILL SPREAD SHOWERS ALONG
AND AHEAD OF A COLD FRONT WEDNESDAY NIGHT INTO THURSDAY. COLDER AIR
IS FORECAST TO SPILL INTO THE REGION THURSDAY NIGHT INTO FRIDAY IN
THE WAKE OF THE LOW/COLD FRONT. THIS WILL CHANGE ANY LIQUID PCPN TO
SNOW SHOWERS WHILE TEMPERATURES DROP. HAVE LIMITED SNOW SHOWERS TO
THE CHANCE CATEGORY THURSDAY NIGHT INTO FRIDAY DUE TO WRAP AROUND
MOISTURE AND COLDER AIR MOVING ACROSS THE WARMER WATER OF THE GREAT
LAKES. ANY SNOW ACCUMULATION SHOULD BE MINOR BUT WILL DEPEND ON THE
EXACT TRACK AND CLOSING OF MID LVL S/WV INTO A MID LEVEL
CIRCULATION. AGAIN...WAY TOO EARLY TO KNOW AT THIS POINT GIVEN THE
MODEL SPREAD MENTIONED. TEMPERATURES WILL DROP TO BELOW NORMAL
READINGS ON FRIDAY IN THE CAA PATTERN.
FOR FRIDAY NIGHT INTO SATURDAY...MODELS ARE IN DISAGREEMENT ON HOW
FAST UPR LVL LOW WILL PULL NE AND WHETHER IT WILL ROTATE BACK TOWARD
THE SOUTHWEST INTO EARLY NEXT WEEK. HAVE GONE WITH PARTLY CLOUDY
SKIES AT THIS POINT WITH A SMALL CHANCE OF SNOW SHOWERS DOWN WIND OF
THE GREAT LAKES...MAINLY ACROSS OUR NRN AND ERN LOCATIONS.
TEMPERATURES ARE EXPECTED TO BE BELOW NORMAL.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
MAIN CHANGES WITH THE 00Z TAF FORECAST WAS TO TREND AWAY FROM IFR
CIGS A LITTLE TONIGHT...ESPECIALLY BEFORE 06Z...BUT STILL HINT AT
THIS DEVELOPMENT LATER IN THE NIGHT. VFR STRATUS HAS OVERSPREAD
ALL TAF SITES AND CONTINUES TO STEADILY LOWER AS MOISTURE
ADVECTION CONTINUES AS VEERING WINDS TAP THE LOW LEVEL MOISTURE
PLUME OFF TO OUR SOUTHWEST.
CONFLICTING GUIDANCE IN SOME OF THE SHORT TERM MODELS ON JUST HOW
LOW THE CIGS DROP TONIGHT...WITH EXPERIMENTAL HRRR AND
DETERMINISTIC NAM AND NAM-BASED MOS MOST AGGRESSIVE. EXPERIMENTAL
ENSEMBLE PRODUCTS /NARRE/ AND GFS LAMP...AS WELL AS GFS-BASED MOS
A GREAT DEAL LESS BULLISH. CURRENTLY UPSTREAM...CIGS HOLDING IN
MVFR CATEGORIES FROM 012-030KFT.
EXPECT MVFR CIGS TO OVERSPREAD ALL SITES THIS EVENING AND LOWER
BELOW 02KFT BY 06Z. STEADY/INCREASING SSWLY WINDS WILL KEEP VSBYS
MAINLY VFR THROUGH 09Z...BUT AT THE END OF THE NIGHT A SLIGHT
WEAKENING OF THE WIND AND PUSH OF DEEPER LOW LEVEL MOISTURE MAY
ALLOW FOR A PERIOD OF IFR CIGS AND/OR MVFR VIS AT MOST SITES.
CAN/T RULE OUT A PATCH OR TWO OF DRIZZLE AT ANY SITE AS
WELL...THOUGH MOISTURE DEPTHS SEEM A LITTLE TO SHALLOW FOR
WIDESPREAD -DZ.
ON SUNDAY...EXPECT A SLOW IMPROVEMENT AS GUSTY SWLY WINDS DEVELOP
AND CLOUD BASE SLOWLY LIFTS/BREAKS UP. WILL TAKE SOME TIME - AND
WON/T BE UNTIL AFTER 16Z OR SO THAT MARKED IMPROVEMENT IS SEEN.
MAY BE A ROGUE SHOWER/STORM LATER IN THE TAF PERIOD ESP FOR
CVG/ILN/LUK BUT NOWHERE NEAR THE CONFIDENCE RIGHT NOW TO INSERT.
OUTLOOK...ISOLATED/SCT THUNDERSTORMS ARE POSSIBLE SUNDAY AFTN AND
EVE. MVFR CEILINGS AND VISIBILITIES POSSIBLE SUNDAY NIGHT INTO
TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...BINAU
SHORT TERM...HATZOS
LONG TERM...HICKMAN
AVIATION...BINAU
AREA FORECAST DISCUSSION
NWS TULSA OK
412 PM CST FRI DEC 14 2012
.DISCUSSION...
AN INITIAL BAND OF SHOWERS IS MOVING ACROSS THE AREA AT THIS TIME.
THERE WILL THEN BE A RELATIVE LULL IN THE ACTIVITY LATE THIS
AFTERNOON AND EARLY THIS EVENING UNTIL A SECOND BAND OF SHOWERS
AND PERHAPS AN ISOLATED THUNDERSTORM OR TWO AFFECTS THE AREA LATER
THIS EVENING. THIS SECOND BAND WILL BE THE REMNANTS OF THE CURRENT
SEVERE SQUALL LINE ACROSS THE TEXAS PANHANDLE...WHICH WILL WEAKEN
AS IT MOVES INTO A MUCH MORE STABLE AIRMASS ACROSS CENTRAL AND
EASTERN OKLAHOMA.
HAVE KEPT THE ISOLATED THUNDER MENTION ACROSS PARTS OF NORTHEAST
OKLAHOMA AND ALSO ADDED ISOLATED THUNDER TO FAR SOUTHEAST
OKLAHOMA. THE HRRR SUGGESTS A SEPARATE CONVECTIVE LINE WILL FORM
ACROSS NORTHERN TEXAS LATER THIS EVENING WHERE INSTABILITY WILL BE
GREATEST...AND FAR SOUTHEAST OKLAHOMA MAY BE AFFECTED BY THIS LINE.
RAIN WILL END AND SKIES WILL BEGIN TO CLEAR LATE TONIGHT. SATURDAY
WILL BE A BREEZY AND WARM DAY WHICH WILL RAISE FIRE WEATHER
CONCERNS. AT THIS POINT...CONDITIONS LOOK LIKE THEY WILL REMAIN
JUST BELOW RED FLAG CRITERIA.
A WEAK COLD FRONT WILL KNOCK TEMPERATURES BACK A FEW DEGREES
SUNDAY AND MONDAY...BUT THEY WILL STILL BE WELL ABOVE THE SEASONAL
NORMALS. WEDNESDAY WILL SEE A RETURN TO UNSEASONABLY WARM
TEMPERATURES BEFORE A STRONGER COLD FRONT SWEEPS ACROSS THE AREA
LATER WEDNESDAY NIGHT RETURNING TEMPERATURES BACK TO NEAR NORMAL
IN ITS WAKE. LIMITED MOISTURE RETURN AHEAD OF THIS FRONT MEANS
THAT IT WILL LIKELY PASS THROUGH DRY.
STAYED CLOSE TO GUIDANCE TEMPERATURES THE NEXT COUPLE DAYS.
CURRENT READINGS AT A FEW SPOTS IN EASTERN OKLAHOMA ARE SLIGHTLY
BELOW THE FORECAST LOWS FOR TONIGHT DUE TO WET BULB COOLING WITH
THE RAIN...BUT READINGS SHOULD RECOVER SOME BEFORE THE 01Z
VERIFICATION START TIME.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 47 68 38 62 / 90 10 10 10
FSM 45 71 43 68 / 80 10 10 10
MLC 47 70 43 67 / 80 10 10 10
BVO 44 67 33 60 / 90 10 10 10
FYV 45 66 39 61 / 80 10 10 10
BYV 46 66 40 61 / 80 10 10 10
MKO 46 69 39 64 / 90 10 10 10
MIO 46 66 37 59 / 90 10 10 10
F10 47 69 42 64 / 80 10 10 10
HHW 47 71 43 69 / 80 10 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
SHORT TERM...12
LONG TERM....05
PLATE
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
834 PM CST SAT DEC 15 2012
.UPDATE...
FORECAST FOR TONIGHT APPEARS ON TRACK AND ONLY MINOR TWEAKS WERE
MADE. WAA CONTINUES TO INCREASE OVER THE MID STATE WITH DEWPOINTS
NOW IN THE MID 40S TO MID 50S. TEMPERATURES HAVE ALSO BEGUN RISING
OVER THE WESTERN HALF AND RAISED LOW TEMPS OVER THAT REGION.
HOWEVER...HAD TO LOWER MINS ON THE PLATEAU WHERE TEMPS ARE
ALREADY NEAR/BELOW FORECAST LOWS...BUT TEMPS SHOULD REMAIN STEADY
OR SLOWLY RISE THERE THE REMAINDER OF THE NIGHT AS WELL.
CURRENT RADAR IMAGERY INDICATES AN AREA OF RAIN WITH A COUPLE OF
THUNDERSTORMS OVER THE PLATEAU. ADDITIONAL ACTIVITY IS FORMING
OVER THE LOWER MISSISSIPPI VALLEY...AND SHORT TERM GUIDANCE
INDICATES THIS WILL SPREAD ACROSS THE MID STATE OVERNIGHT.
ANTICIPATING SOME STRONGER CONVECTION AFTER MIDNIGHT PER 00Z NAM
AND 23Z HRRR RUNS...AND CANNOT RULE OUT AN ISOLATED STRONG OR
MARGINALLY SEVERE STORM OVER SOUTHERN AND EASTERN ZONES. WITH
ACTIVITY ELEVATED ABOVE THE SURFACE INVERSION PER 00Z OHX
SOUNDING...MAIN THREATS WOULD BE GUSTY WINDS OR HAIL DUE TO THE
INTENSE LOW LEVEL SHEAR.
&&
.PREV DISCUSSION... /ISSUED 745 PM CST SAT DEC 15 2012/
UPDATE...FOR AVIATION FORECAST
AVIATION...
ELEVATED SHOWER ACTIVITY IS ON-GOING OVER EASTERN AND SOUTHERN SECTIONS
OF THE MID STATE WITH AN OCCASIONAL LIGHTNING STRIKE IN SOME OF THE
STRONGER RETURNS. THIS ACTIVITY REMAINS ELEVATED AND WILL CONTINUE
TO MOVE QUICKLY TOWARD THE NORTHEAST AS WIND FIELDS WILL REMAIN
STRONG ABOVE SURFACE. THERE IS NEWLY DEVELOPED ACTIVITY OVER
NORTHWEST MISSISSIPPI AT 01Z THIS EVENING THAT WILL BE MOVING THIS
WAY ALONG WITH ACTIVITY THAT HAS FIRED FARTHER TO THE SOUTHWEST
OVER NORTHERN LOUISIANA DURING THE PAST HOUR. SREF KEEPS THE BULK
OF THIS ACTIVITY OVER THE SOUTHEAST HALF OF MIDDLE TENNESSEE...GENERALLY
SOUTH AND EAST OF NASHVILLE THROUGH 12Z SUNDAY. AFTER 12Z SUNDAY
ACTIVITY WILL BECOME MORE NUMEROUS ACROSS MIDDLE TENNESSEE EXCEPT
FOR FAR NORTHWEST WHERE IT WILL BE SCATTERED. MARGINALLY SEVERE
STORM OR TWO POSSIBLE ON SUNDAY...ESPECIALLY NEAR ALABAMA BORDER.
WILL UPDATE AVIATION FORECAST AND TWEAK TIMING FOR CONVECTION.
BOYD
PREV DISCUSSION... /ISSUED 617 PM CST SAT DEC 15 2012/
UPDATE...FOR 00Z AVIATION FORECAST
AVIATION...
STILL A RATHER TIGHT SURFACE PRESSURE GRADIENT ACROSS THE TENNESSEE
VALLEY WITH SURFACE GEOSTROPHIC WINDS ON THE ORDER OF 45 TO 50 KNOTS
AT THE TOP OF THE BOUNDARY LAYER. LOW LEVEL JET CURRENTLY PUNCHING
ACROSS EASTERN ARKANSAS AND UP THROUGH WESTERN TENNESSEE AND
KENTUCKY WITH A 160 KNOT UPPER LEVEL JET FROM OKLAHOMA EASTWARD
THROUGH THE OHIO/TENNESSEE VALLEYS. TOTAL TOTALS THIS EVENING ARE
HIGHER TO OUR SOUTH ACROSS NORTHERN ALABAMA/MISSISSIPPI. BUFKIT
SOUNDINGS OFF GFS SHOWING GOOD INVERSION OFF SURFACE DURING MUCH
OF THE OVERNIGHT HOURS SO ANY CONVECTION SHOULD REMAIN ELEVATED
AND ZIP ALONG AT A PRETTY GOOD SPEED OFF TOWARD THE NORTHEAST.
BASICALLY KEPT WHAT THE DAYSHIFT HAD AS FAR AS AVIATION FORECASTS
BUT WILL TAKE CLOSER WHEN NEWER GUIDANCE ARRIVES AND UPDATE
PACKAGE IF NEED BE DURING THE EVENING.
BOYD
PREV DISCUSSION... /ISSUED 254 PM CST SAT DEC 15 2012/
DISCUSSION...
SURFACE ENERGY TO CONTINUE TO PULL NORTH THROUGH THIS AFTERNOON AND
TONIGHT. HOWEVER...SOUTHWESTERLY FLOW ALOFT TO BECOME MORE ACTIVE AS
A SERIES OF IMPULSES RIDES NORTHEAST WITHIN THE FLOW. MOISTURE LEVELS
TO REMAIN WITH SOME ENHANCEMENT EXPECTED OVERNIGHT AND INTO SUNDAY.
A RELATIVELY WEAK FRONTAL BOUNDARY WILL HEAD OUR WAY WITH THE FROPA
EXPECTED ON MONDAY.
PRESSURE GRADIENTS TO REMAIN ON THE TIGHT SIDE THROUGH MONDAY. 10-20
MPH WINDS WITH SOME HIGHER GUSTS TO LIKELY PREVAIL.
OVERALL FOR THE SHORT TERM...RAINFALL CHANCES WILL BE GREATEST
TONIGHT AND SUNDAY WITH THE ACTIVE SOUTHWESTERLY UPPER FLOW. THE
TRAJECTORY AND IMPACT OF THE IMPULSES WILL BE GREATEST ACROSS
SOUTHERN MIDDLE TN AND THE PLATEAU. FOR SUNDAY NIGHT AND
MONDAY...MOISTURE LEVELS WILL DROP BUT THE APPROACHING WEAK FRONTAL
BOUNDARY WILL PROVIDE GENERALLY LOW RAINFALL CHANCES.
IN TERMS OF TSTM POTENTIAL...SHOWALTERS ARE NEAR ZERO WITH LIMITED
SFC CAPE VALUES. WILL STILL INCLUDE ISOL/SCT TSTMS FOR EACH PERIOD.
FOR THE NEAR TERM TEMPS...WARM PATTERN WITH THE MOIST SOUTHERN
DIRECTIONALLY UNIFORM FLOW. SLIGHTLY COOLER FOR MONDAY NIGHT BEHIND
THE FROPA BUT STILL ABOVE NORMAL. REPLACING AIRMASS WILL FEATURE A
SFC HIGH THAT WILL BUILD SLIGHTLY NORTHWARD FROM THE GULF. SO MILD
CONDITIONS TO CONTINUE BEHIND THE FROPA.
IN THE EXTENDED FCST...TUESDAY AND WEDNESDAY WILL FEATURE MOSTLY
SUNNY AND MILD CONDITIONS. THEN... A STRONG COLD FRONT WILL GAIN
STRENGTH AND PUSH ACROSS THE AREA ON THURSDAY. SHOWERS AND TSTMS
LOOK LIKE A GOOD BET FOR THURSDAY AS THE EURO AND GFS SOLUTIONS
MATCH UP QUITE WELL. LOOKS LIKE UP TO AN INCH OF RAINFALL POSSIBLE.
INSTABILITIES ARE JUST STRONG ENOUGH TO WARRANT ISOL TSTMS AS WELL.
COLDER CONDITIONS TO RETURN BEHIND THE FRONT. VERSUS THE MEX...WILL
UNDERCUT RATHER AGGRESSIVELY FOR FRIDAY AND SATURDAY.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHAMBURGER
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
512 PM CST SAT DEC 15 2012
.DISCUSSION...
/SEE BELOW FOR AVIATION DISCUSSION/
&&
.AVIATION...
VFR NEXT 24 HOURS. MID AND UPPER LEVEL HIGH CLOUDINESS ASSOCIATED
WITH THE SUBTROPICAL JET WILL PERSIST OVERNIGHT AND INTO SUNDAY
MORNING. GUSTY WINDS OF 25-28 KTS TOWARD NOON AT KSJT AND KABI AS
A SURFACE LOW MOVES EAST ACROSS THE TEXAS AND OKLAHOMA PANHANDLES.
04
&&
.PREV DISCUSSION... /ISSUED 306 PM CST SAT DEC 15 2012/
SHORT TERM...
TEMPERATURES THIS AFTERNOON RANGE FROM THE LOWER 60S ACROSS THE
NORTHERN BIG COUNTRY TO THE MID 70S ACROSS THE NORTHWEST HILL
COUNTRY. THE GUSTY WEST WINDS THAT WERE FORECAST FOR TODAY NEVER
REALLY MATERIALIZED DUE...IN LARGER PART...TO THE THICK MID/HIGH
CLOUD COVER THAT MOVED IN FROM THE SOUTH AND WEST. THIS IS IN
RESPONSE TO A 150 KT H25 SUBTROPICAL JET STREAK ORIENTED FROM
NORTHWEST MEXICO INTO SOUTHWEST OK. THIS JET AXIS IS PROGGED TO
SLIDE JUST TO OUR SOUTHEAST OVER THE NEXT 24 HOURS WHICH WOULD HELP
ELIMINATE MUCH OF THE HIGH CLOUDS OVER OUR CWA. IN THE MEANTIME...
WE CAN EXPECT MOSTLY CLOUDY SKIES OVERNIGHT WHICH GENERALLY MEANS
WARMER TEMPS THAN THOSE SUGGESTED BY GUIDANCE. I INCREASED MINS
ACROSS THE I-10 CORRIDOR WHERE THE THICKEST CLOUD COVER IS EXPECTED.
OTHERWISE...GUIDANCE LOOKED GOOD WITH LOW 40S. THE RAP WAS
GENERATING LIGHT QPF TONIGHT BUT IT REMAINS AN OUTLIER AND LOOKS
SUSPICIOUS AT BEST.
I EXPECT AT LEAST PARTIAL CLEARING SUNDAY AFTERNOON. THIS SHOULD
ALLOW SOME OF THE STRONGER WINDS ALOFT TO MIX DOWN TO THE SURFACE
AND PROVIDE A FEW HOURS OF GUSTY WEST WINDS. I STILL THINK WIND
SPEEDS WILL REMAIN IN THE 15-20 MPH RANGE ACROSS THE BIG COUNTRY AND
CONCHO VALLEY /LIGHTER ELSEWHERE/ DESPITE TODAY/S HUMBLING EXAMPLE.
THE ENHANCED DOWNSLOPE SHOULD HELP PUSH TEMPS BACK INTO THE UPPER
60S TO LOWER 70S AS H85 TEMPS ARE ONLY PROGGED TO COOL BY AROUND 1C
BY 00Z MONDAY.
JOHNSON
LONG TERM...
THE EXTENDED FORECAST IS CHARACTERIZED BY GENERALLY ABOVE NORMAL
TEMPERATURES AND LITTLE TO NO CHANCE OF PRECIPITATION. AN UPPER
LEVEL TROUGH WILL MOVE ACROSS THE PLAINS ON MONDAY...WITH THE ONLY
REAL AFFECT ON WEST CENTRAL TEXAS BEING AN INCREASE IN WINDS. EXPECT
WEST NORTHWEST WINDS OF 15 TO 20 MPH...WITH TEMPERATURES RANGING
FROM THE MID 60S TO LOWER 70S. A STEADY WARM UP IS FORECAST ON
TUESDAY AND WEDNESDAY AHEAD OF THE NEXT UPPER LEVEL TROUGH. HIGH
TEMPERATURES WILL BE RUNNING 15 TO 20 DEGREES ABOVE SEASONAL
NORMALS...GENERALLY IN THE LOWER TO MID 70S. THE MAIN WEATHER
CONCERN WILL BE THE POTENTIAL FOR STRONG WINDS ON WEDNESDAY. A
FAIRLY POTENT UPPER LEVEL TROUGH WILL APPROACH THE AREA ON
WEDNESDAY...WITH A 994MB SURFACE LOW DEVELOPING OVER THE TEXAS
PANHANDLE. A TIGHT SURFACE PRESSURE GRADIENT WILL DEVELOP ACROSS THE
REGION...RESULTING IN WEST WINDS OF 20 TO 30 MPH...WITH HIGHER
GUSTS...ACROSS MUCH OF THE BIG COUNTRY AND CONCHO VALLEY. FARTHER
SOUTH WINDS SHOULD REMAIN IN THE 15 TO 25 MPH RANGE.
AS THE AFOREMENTIONED UPPER LEVEL TROUGH SWINGS ACROSS THE
PLAINS...A COLD FRONT WILL QUICKLY MOVE THROUGH THE AREA WEDNESDAY
NIGHT. NORTH WINDS OF 15 TO 20 MPH AND COOLER TEMPERATURES CAN BE
EXPECTED BEHIND THE FRONT. I LOWERED HIGH TEMPERATURES BY A FEW
DEGREES FOR THURSDAY...GENERALLY IN THE MID AND UPPER 50S. A CHILLY
MORNING IS FORECAST FRIDAY. SKIES WILL BE MOSTLY CLEAR...DEWPOINTS
WILL BE IN THE SINGLE DIGITS AND SKIES WILL BECOME LIGHT. THE
CURRENT FORECAST HAS LOW TEMPERATURES RANGING FROM THE MID TO UPPER
20S...AND THESE MAY NEED TO LOWERED SLIGHTLY ON FUTURE SHIFTS. A
SLOW WARM UP WILL ENSUE THROUGH NEXT WEEKEND...WITH NO CHANCE OF
PRECIPITATION.
DANIELS
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 70 44 69 38 66 / 0 0 0 0 0
SAN ANGELO 72 41 71 37 68 / 0 0 0 0 0
JUNCTION 75 43 74 36 71 / 0 5 0 0 0
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
99/99/04
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1225 PM CST FRI DEC 14 2012
.AVIATION...
MVFR CONDITIONS REMAIN IN PLACE AT KCDS DUE TO STRATUS. KLBB HAS
MOMENTARILY COME UP TO VFR AS SKIES HAVE CLEARED ACROSS PORTIONS
OF THE SOUTH PLAINS...BUT BLOWING DUST WILL DAMPER VISIBILITIES
INTO THE MVFR OR PERHAPS IFR CATEGORY THIS AFTERNOON. A LINE OF
SHOWERS AND THUNDERSTORMS WILL MOVE FROM WEST TO EAST BEGINNING
EARLY-MID AFTERNOON. KLBB CAN EXPECT STORMS BEGINNING AFTER 21Z
WHILE KCDS WILL BE CLOSER TO 23Z WITH ALL ACTIVITY ENDING BY 02Z.
WINDS WILL VEER TO THE SOUTHWEST TO WEST AS THESE STORMS AND
ASSOCIATED FRONT MOVE THROUGH THIS AFTERNOON. SPEEDS WILL INCREASE
TO NEAR 35 KNOTS AT KLBB WITH GUSTS APPROACHING 50 KNOTS WHILE
KCDS WILL SEE RELATIVELY LOWER SPEEDS IN THE 20-25 KNOT RANGE WITH
GUSTS TO 30 KNOTS.
&&
.PREV DISCUSSION... /ISSUED 1102 AM CST FRI DEC 14 2012/
UPDATE...
FORECAST REMAINS INTACT FOR TODAY AS STRONG TO SEVERE
THUNDERSTORMS...HIGH WINDS...AND BLOWING DUST WILL ALL IMPACT
PORTIONS OF THE EXTREME SOUTHERN TEXAS PANHANDLE...SOUTH
PLAINS...AND ROLLING PLAINS.
SPRINKLES AND LIGHT SHOWERS WILL END BY LATE MORNING ACROSS
EXTREME EASTERN PORTIONS OF THE PANHANDLE AND ROLLING PLAINS.
VIGOROUS UPPER TROUGH MOVING INTO THE DESERT SOUTHWEST WILL CONTINUE
TO MOVE NORTHEAST TOWARD THE SOUTHERN PLAINS TODAY. SCATTERED TO
NUMEROUS THUNDERSTORMS WILL DEVELOP AHEAD OF THIS TROUGH ALONG A
PACIFIC FRONT AT THE SURFACE THIS AFTERNOON. CONVECTIVE
DEVELOPMENT LOOKS TO INITIATE AROUND 20-21Z NEAR THE TX/NM STATE
LINE AND RACE EAST ACROSS THE AREA BY WAY OF AN INTENSE WIND
FIELD CAPPED BY A 150+ KNOT JET AT H25. NEAR 40 KNOTS OF 0-1 KM
SHEAR WILL BE PRESENT ALONG THE FRONT AS IT MOVES THROUGH WITH
VECTORS NEAR PERPENDICULAR TO THE PACIFIC FRONT/DRYLINE. DAMAGING
WIND GUSTS WILL BE THE PRIMARY THREAT AS WEAKENING LAPSE RATES
ALOFT WILL LIMIT OVERALL HAIL POTENTIAL. A BRIEF TORNADO OR TWO
CANNOT BE RULED OUT IN ISOLATED LOW-TOPPED SUPERCELLS EITHER
GIVEN THE SUBSTANTIAL DEEP-LAYER SHEAR.
HIGH WIND WARNING WILL STAY IN EFFECT FROM 20-00Z MAINLY FROM
INTERSTATE 27 WEST AS SUBSIDENCE OCCURS BEHIND THE CONVECTIVE
LINE AND FRONT. MIXING TO AT LEAST H85 SHOULD BE ABLE TO OCCUR
AND BRING A PORTION OF THE 45-50 KNOT WINDS HERE DOWN TO THE
SURFACE. THIS SHOULD ALLOW FOR SOME AREAS TO SEE SUSTAINED WINDS
OF 40 MPH AT TIMES THIS AFTERNOON WITH GUSTS TO 58 MPH. THIS
GRADIENT FLOW MAY COMBINE WITH CONVECTIVE GUSTS AT TIMES TO ALSO
PRODUCE WINDS OF THIS MAGNITUDE. WITH WINDS THIS HIGH...SHOULD
ALSO SEE AREAS OF BLOWING DUST ON THE CAPROCK THIS AFTERNOON WHICH
MAY HINDER VISIBILITIES.
PREV DISCUSSION... /ISSUED 501 AM CST FRI DEC 14 2012/
SHORT TERM...
MULTI-FACETED AND EXCEPTIONALLY ACTIVE WEATHER FOR MID-DECEMBER
AWAITS THE SOUTH PLAINS LATER TODAY AS A VIGOROUS UPPER LOW LIFTS
NORTHEAST FROM NORTHERN BAJA IN THE FORM OF A NEGATIVELY TILTED
TROUGH. EARLY MORNING WATER VAPOR DEPICTION OF SAID LOW WAS QUITE
IMPRESSIVE AND FEATURED A DEEPENING PLUME OF SUBTROPICAL MOISTURE
AND SOME THUNDERSTORMS WELL IN ITS ADVANCE. ABUNDANT LOW-LEVEL
MOISTURE ADVECTION CONTINUED OVER WEST TX THIS MORNING AND WILL
ONLY CONTINUE THROUGH 18Z AS RESPECTABLE PRESSURE FALLS AROUND
7MB/6HR FOCUS IN ERN NM AHEAD OF THE EJECTING WAVE. THIS WILL KEEP
MOIST SOUTHERLY WINDS...STRATUS AND SOME FOG INTACT LONGER THAN
ORIGINALLY FORECAST BEFORE STRONG HEIGHT FALLS /60+ METERS AT
500MB/ UNFOLD BY EARLY AFTN ALONG THE NM-TX STATE LINE. ALONG WITH
A 135 KNOT UPPER SPEED MAX...A PACIFIC FRONT ACCOMPANYING THE
LEADING EDGE OF HEIGHT FALLS SHOULD EASILY SECURE DEEP ASCENT
WHILE PUTTING OUR SEASONABLY HIGH DEWPOINTS TO WORK.
CONSIDERING THE FLOW AHEAD OF THIS TROUGH IS MORE MERIDIONAL THAN
MODELS INDICATED JUST A FEW DAYS AGO...THE CHANCES OF A DRY FROPA
HAVE NOW GREATLY DIMINISHED. AFTERNOON POPS WERE DOUBLED NEARLY
AREA WIDE WITH JUST SLIGHT CHANCES OF MRNG SHOWERS CONFINED MAINLY
OFF THE CAPROCK WHERE DEEPER MOIST ADVECTION WITHIN A LLJ AXIS
COULD FAVOR VERY LIGHT PRECIP.
ALTHOUGH STRATUS WILL BE VERY SLOW TO ERODE...AMPLE MID-LEVEL
COOLING ACCOMPANYING THE UPPER TROUGH IS STILL SHOWN TO GARNER
WEAK SBCAPE AOB 600 J/KG BY 21Z WITH SURFACE TEMPS IN THE 50S-
60S. IT IS NOT UNCOMMON TO SEE SOME SEVERE CONVECTIVE MODES UNFOLD
IN SUCH LOW CAPE AND HIGH SHEAR ENVIRONMENTS PROVIDED
STRONG/FOCUSED ASCENT EMERGES. INITIAL SWODY1 ACCOUNTS FOR THIS
SCENARIO AND SEVERAL HI RES MODELS INCLUDING THE TTU-WRF DEPICT A
BROKEN LINE OF PARTICULARLY STRONG CELLS ACCOMPANYING FROPA. SUCH
A SCENARIO INVOLVING DMGG DOWNBURST WINDS OCCURRED HERE IN MID
DECEMBER 1993 FROM A SIMILAR SYNOPTIC PATTERN. AS WAS THE CASE
THEN...SEVERE WIND GUSTS WOULD BE THE DOMINANT THREAT WITH STORMS
TODAY AS STRONG KINEMATIC FLOW OVERSPREADS THE REGION. VERY MEAGER
CAPE IN THE HAIL GROWTH REGION SHOULD KEEP SEVERE HAIL PRODUCTION
AT BAY.
IN ADDITION TO A THREAT OF SEVERE CONVECTIVE WINDS...PATTERN
RECOGNITION BEHIND THE FRONT BY MID/LATE AFTERNOON DOES FAVOR AN
ABBREVIATED NON-CONVECTIVE HIGH WIND EVENT. A 500MB WIND MAX OF 100
KNOTS IS PROGGED TO OVERSPREAD OUR SWRN COUNTIES BY 21Z COMPLETE
WITH 60-70 KNOTS AT THE TOP OF THE MIXING LAYER AROUND 700MB OVER
MUCH OF THE CAPROCK. STRONG POST-FRONTAL SUBSIDENCE AND DRYING ON
SWLY WINDS SHOULD ALLOW FOR AN ABBREVIATED WINDOW OF 40G58 MPH
CONDITIONS OR HIGHER IMMEDIATELY FOLLOWING THE PACIFIC FRONT UNTIL
BOUNDARY LAYER DECOUPLING ENSUES BY 00Z. MOS GUIDANCE IS WELL
SHORT OF HIGH WIND CRITERIA...BUT WE BELIEVE MUCH OF THIS IS DUE
TO THE RELATIVELY SHORT DURATION OF HIGH WINDS THAT WE ANTICIPATE
WILL DEVELOP LATE IN THE DAY. TTU-WRF AND HRRR CONTINUE TO
CHAMPION SUCH CONDITIONS FOR A FEW HOURS FOLLOWING FROPA WITH
GUSTS AROUND 60 MPH TAKING AIM MAINLY WEST OF I-27.
LONG TERM...
ALTHOUGH WIND SPEEDS WILL DECREASE A BIT TONIGHT INTO SATURDAY
MORNING...EXPECT THEM TO ONCE AGAIN RAMP UP SOME SATURDAY
AFTERNOON AS ANOTHER APPROACHING SHORTWAVE TROF KEEPS A TIGHT
PRESSURE GRADIENT OVER THE REGION. SOIL WILL HAVE DRIED OUT SOME
FROM ANY RAINFALL TODAY AND CONDITIONS WILL ONCE AGAIN FAVOR SOME
AREAS OF BLOWING DUST SATURDAY AFTERNOON. THIS STORM SYSTEM WILL
RAPIDLY PUSH EAST SATURDAY NIGHT BEFORE ANOTHER TROF PUSHES OVER
THE AREA FOR SUNDAY AFTERNOON. THIS THIRD STORM SYSTEM WILL NOT BE
QUITE AS STRONG BUT WILL LIKELY RESULT IN BREEZY CONDITIONS AGAIN
FOR SUNDAY AFTERNOON. THROUGH THE WEEKEND...TEMPERATURES WILL ALSO
SLOWLY COOL AS CONTINUED COLD AIR ADVECTION TAKES PLACE KEEPING
READINGS CLOSE TO NORMAL FOR THIS TIME OF YEAR.
DRY WEATHER WILL BE EXPECTED FOR THE FIRST PART OF NEXT WEEK AS
DRY NORTHWESTERLY FLOW GRADUALLY TRANSITIONS TO SOUTHWESTERLY BY
MID-WEEK. THIS WILL ALLOW TEMPERATURES TO ONCE AGAIN CLIMB TO
ABOVE NORMAL THROUGH WEDNESDAY. ALSO BY MID-WEEK...ANOTHER
CANADIAN COLD FRONT WILL PUSH SOUTH THROUGH THE CENTRAL PLAINS
AND ARRIVE SOMETIME LATE WEDNESDAY INTO THURSDAY MORNING. THIS
FRONTAL PASSAGE SHOULD BE DRY AS LITTLE MOISTURE RECOVERY TAKES
PLACE BEFORE IT MOVES THROUGH. THIS FRONT WILL DROP TEMPERATURES
BACK DOWN TO NORMAL FOR THE END OF THE WEEK.
JORDAN
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 58 30 57 26 55 / 60 0 0 0 0
TULIA 60 33 59 28 55 / 60 0 0 0 0
PLAINVIEW 60 33 59 28 55 / 60 0 0 0 0
LEVELLAND 62 32 60 30 57 / 60 0 0 0 0
LUBBOCK 62 34 61 31 57 / 60 0 0 0 0
DENVER CITY 62 31 62 32 59 / 40 0 0 0 0
BROWNFIELD 63 33 62 31 59 / 50 0 0 0 0
CHILDRESS 62 40 65 34 61 / 60 20 0 0 0
SPUR 62 38 65 34 64 / 50 10 0 0 0
ASPERMONT 64 41 68 38 66 / 30 20 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 6 PM CST THIS EVENING FOR THE FOLLOWING
ZONES: TXZ021>023-027>029-033>035-039>041.
&&
$$
31
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1102 AM CST FRI DEC 14 2012
.UPDATE...
FORECAST REMAINS INTACT FOR TODAY AS STRONG TO SEVERE
THUNDERSTORMS...HIGH WINDS...AND BLOWING DUST WILL ALL IMPACT
PORTIONS OF THE EXTREME SOUTHERN TEXAS PANHANDLE...SOUTH
PLAINS...AND ROLLING PLAINS.
SPRINKLES AND LIGHT SHOWERS WILL END BY LATE MORNING ACROSS
EXTREME EASTERN PORTIONS OF THE PANHANDLE AND ROLLING PLAINS.
VIGOROUS UPPER TROUGH MOVING INTO THE DESERT SOUTHWEST WILL CONTINUE
TO MOVE NORTHEAST TOWARD THE SOUTHERN PLAINS TODAY. SCATTERED TO
NUMEROUS THUNDERSTORMS WILL DEVELOP AHEAD OF THIS TROUGH ALONG A
PACIFIC FRONT AT THE SURFACE THIS AFTERNOON. CONVECTIVE
DEVELOPMENT LOOKS TO INITIATE AROUND 20-21Z NEAR THE TX/NM STATE
LINE AND RACE EAST ACROSS THE AREA BY WAY OF AN INTENSE WIND
FIELD CAPPED BY A 150+ KNOT JET AT H25. NEAR 40 KNOTS OF 0-1 KM
SHEAR WILL BE PRESENT ALONG THE FRONT AS IT MOVES THROUGH WITH
VECTORS NEAR PERPENDICULAR TO THE PACIFIC FRONT/DRYLINE. DAMAGING
WIND GUSTS WILL BE THE PRIMARY THREAT AS WEAKENING LAPSE RATES
ALOFT WILL LIMIT OVERALL HAIL POTENTIAL. A BRIEF TORNADO OR TWO
CANNOT BE RULED OUT IN ISOLATED LOW-TOPPED SUPERCELLS EITHER
GIVEN THE SUBSTANTIAL DEEP-LAYER SHEAR.
HIGH WIND WARNING WILL STAY IN EFFECT FROM 20-00Z MAINLY FROM
INTERSTATE 27 WEST AS SUBSIDENCE OCCURS BEHIND THE CONVECTIVE
LINE AND FRONT. MIXING TO AT LEAST H85 SHOULD BE ABLE TO OCCUR
AND BRING A PORTION OF THE 45-50 KNOT WINDS HERE DOWN TO THE
SURFACE. THIS SHOULD ALLOW FOR SOME AREAS TO SEE SUSTAINED WINDS
OF 40 MPH AT TIMES THIS AFTERNOON WITH GUSTS TO 58 MPH. THIS
GRADIENT FLOW MAY COMBINE WITH CONVECTIVE GUSTS AT TIMES TO ALSO
PRODUCE WINDS OF THIS MAGNITUDE. WITH WINDS THIS HIGH...SHOULD
ALSO SEE AREAS OF BLOWING DUST ON THE CAPROCK THIS AFTERNOON WHICH
MAY HINDER VISIBILITIES.
&&
.PREV DISCUSSION... /ISSUED 554 AM CST FRI DEC 14 2012/
AVIATION...
STRATUS...STRONG TSRA...HIGH WINDS...AND BLOWING DUST WILL MAKE
FOR DETERIORATING CONDITIONS TODAY. HIGH CONFIDENCE THAT MORNING
MVFR STRATUS WILL REMAIN LARGELY UNDISTURBED THROUGH EARLY
AFTERNOON. THIS LAYER MAY OCCASIONALLY DROP TO HIGH-END IFR
LEVELS BEFORE 16Z AT LBB...BUT A MUCH BETTER CHANCE OF IFR
CONDITIONS AT LBB WILL ACCOMPANY A FAST-MOVING COLD FRONT AROUND
22Z AS 30-40 KNOT SWLY WINDS REDUCE VISBYS TO 1SM OR LESS IN BLDU.
CDS SHOULD ESCAPE THESE EFFECTS...HOWEVER BOTH TERMINALS WILL
LIKELY SEE A BROKEN LINE OF TSRA ACCOMPANY THE FRONT COMPLETE WITH
LOCALLY DMGG WINDS. SUSPENDED DUST MAY LINGER FOR A FEW HOURS AT LBB
AFTER SUNSET WHEN WINDS SUBSIDE...BUT AS A WHOLE VFR CONDITIONS
SHOULD EMERGE BY EARLY EVENING AT BOTH STATIONS.
PREV DISCUSSION... /ISSUED 501 AM CST FRI DEC 14 2012/
SHORT TERM...
MULTI-FACETED AND EXCEPTIONALLY ACTIVE WEATHER FOR MID-DECEMBER
AWAITS THE SOUTH PLAINS LATER TODAY AS A VIGOROUS UPPER LOW LIFTS
NORTHEAST FROM NORTHERN BAJA IN THE FORM OF A NEGATIVELY TILTED
TROUGH. EARLY MORNING WATER VAPOR DEPICTION OF SAID LOW WAS QUITE
IMPRESSIVE AND FEATURED A DEEPENING PLUME OF SUBTROPICAL MOISTURE
AND SOME THUNDERSTORMS WELL IN ITS ADVANCE. ABUNDANT LOW-LEVEL
MOISTURE ADVECTION CONTINUED OVER WEST TX THIS MORNING AND WILL
ONLY CONTINUE THROUGH 18Z AS RESPECTABLE PRESSURE FALLS AROUND
7MB/6HR FOCUS IN ERN NM AHEAD OF THE EJECTING WAVE. THIS WILL KEEP
MOIST SOUTHERLY WINDS...STRATUS AND SOME FOG INTACT LONGER THAN
ORIGINALLY FORECAST BEFORE STRONG HEIGHT FALLS /60+ METERS AT
500MB/ UNFOLD BY EARLY AFTN ALONG THE NM-TX STATE LINE. ALONG WITH
A 135 KNOT UPPER SPEED MAX...A PACIFIC FRONT ACCOMPANYING THE
LEADING EDGE OF HEIGHT FALLS SHOULD EASILY SECURE DEEP ASCENT
WHILE PUTTING OUR SEASONABLY HIGH DEWPOINTS TO WORK.
CONSIDERING THE FLOW AHEAD OF THIS TROUGH IS MORE MERIDIONAL THAN
MODELS INDICATED JUST A FEW DAYS AGO...THE CHANCES OF A DRY FROPA
HAVE NOW GREATLY DIMINISHED. AFTERNOON POPS WERE DOUBLED NEARLY
AREA WIDE WITH JUST SLIGHT CHANCES OF MRNG SHOWERS CONFINED MAINLY
OFF THE CAPROCK WHERE DEEPER MOIST ADVECTION WITHIN A LLJ AXIS
COULD FAVOR VERY LIGHT PRECIP.
ALTHOUGH STRATUS WILL BE VERY SLOW TO ERODE...AMPLE MID-LEVEL
COOLING ACCOMPANYING THE UPPER TROUGH IS STILL SHOWN TO GARNER
WEAK SBCAPE AOB 600 J/KG BY 21Z WITH SURFACE TEMPS IN THE 50S-
60S. IT IS NOT UNCOMMON TO SEE SOME SEVERE CONVECTIVE MODES UNFOLD
IN SUCH LOW CAPE AND HIGH SHEAR ENVIRONMENTS PROVIDED
STRONG/FOCUSED ASCENT EMERGES. INITIAL SWODY1 ACCOUNTS FOR THIS
SCENARIO AND SEVERAL HI RES MODELS INCLUDING THE TTU-WRF DEPICT A
BROKEN LINE OF PARTICULARLY STRONG CELLS ACCOMPANYING FROPA. SUCH
A SCENARIO INVOLVING DMGG DOWNBURST WINDS OCCURRED HERE IN MID
DECEMBER 1993 FROM A SIMILAR SYNOPTIC PATTERN. AS WAS THE CASE
THEN...SEVERE WIND GUSTS WOULD BE THE DOMINANT THREAT WITH STORMS
TODAY AS STRONG KINEMATIC FLOW OVERSPREADS THE REGION. VERY MEAGER
CAPE IN THE HAIL GROWTH REGION SHOULD KEEP SEVERE HAIL PRODUCTION
AT BAY.
IN ADDITION TO A THREAT OF SEVERE CONVECTIVE WINDS...PATTERN
RECOGNITION BEHIND THE FRONT BY MID/LATE AFTERNOON DOES FAVOR AN
ABBREVIATED NON-CONVECTIVE HIGH WIND EVENT. A 500MB WIND MAX OF 100
KNOTS IS PROGGED TO OVERSPREAD OUR SWRN COUNTIES BY 21Z COMPLETE
WITH 60-70 KNOTS AT THE TOP OF THE MIXING LAYER AROUND 700MB OVER
MUCH OF THE CAPROCK. STRONG POST-FRONTAL SUBSIDENCE AND DRYING ON
SWLY WINDS SHOULD ALLOW FOR AN ABBREVIATED WINDOW OF 40G58 MPH
CONDITIONS OR HIGHER IMMEDIATELY FOLLOWING THE PACIFIC FRONT UNTIL
BOUNDARY LAYER DECOUPLING ENSUES BY 00Z. MOS GUIDANCE IS WELL
SHORT OF HIGH WIND CRITERIA...BUT WE BELIEVE MUCH OF THIS IS DUE
TO THE RELATIVELY SHORT DURATION OF HIGH WINDS THAT WE ANTICIPATE
WILL DEVELOP LATE IN THE DAY. TTU-WRF AND HRRR CONTINUE TO
CHAMPION SUCH CONDITIONS FOR A FEW HOURS FOLLOWING FROPA WITH
GUSTS AROUND 60 MPH TAKING AIM MAINLY WEST OF I-27.
LONG TERM...
ALTHOUGH WIND SPEEDS WILL DECREASE A BIT TONIGHT INTO SATURDAY
MORNING...EXPECT THEM TO ONCE AGAIN RAMP UP SOME SATURDAY
AFTERNOON AS ANOTHER APPROACHING SHORTWAVE TROF KEEPS A TIGHT
PRESSURE GRADIENT OVER THE REGION. SOIL WILL HAVE DRIED OUT SOME
FROM ANY RAINFALL TODAY AND CONDITIONS WILL ONCE AGAIN FAVOR SOME
AREAS OF BLOWING DUST SATURDAY AFTERNOON. THIS STORM SYSTEM WILL
RAPIDLY PUSH EAST SATURDAY NIGHT BEFORE ANOTHER TROF PUSHES OVER
THE AREA FOR SUNDAY AFTERNOON. THIS THIRD STORM SYSTEM WILL NOT BE
QUITE AS STRONG BUT WILL LIKELY RESULT IN BREEZY CONDITIONS AGAIN
FOR SUNDAY AFTERNOON. THROUGH THE WEEKEND...TEMPERATURES WILL ALSO
SLOWLY COOL AS CONTINUED COLD AIR ADVECTION TAKES PLACE KEEPING
READINGS CLOSE TO NORMAL FOR THIS TIME OF YEAR.
DRY WEATHER WILL BE EXPECTED FOR THE FIRST PART OF NEXT WEEK AS
DRY NORTHWESTERLY FLOW GRADUALLY TRANSITIONS TO SOUTHWESTERLY BY
MID-WEEK. THIS WILL ALLOW TEMPERATURES TO ONCE AGAIN CLIMB TO
ABOVE NORMAL THROUGH WEDNESDAY. ALSO BY MID-WEEK...ANOTHER
CANADIAN COLD FRONT WILL PUSH SOUTH THROUGH THE CENTRAL PLAINS
AND ARRIVE SOMETIME LATE WEDNESDAY INTO THURSDAY MORNING. THIS
FRONTAL PASSAGE SHOULD BE DRY AS LITTLE MOISTURE RECOVERY TAKES
PLACE BEFORE IT MOVES THROUGH. THIS FRONT WILL DROP TEMPERATURES
BACK DOWN TO NORMAL FOR THE END OF THE WEEK.
JORDAN
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 58 30 57 26 55 / 60 0 0 0 0
TULIA 60 33 59 28 55 / 60 0 0 0 0
PLAINVIEW 60 33 59 28 55 / 60 0 0 0 0
LEVELLAND 62 32 60 30 57 / 60 0 0 0 0
LUBBOCK 62 34 61 31 57 / 60 0 0 0 0
DENVER CITY 62 31 62 32 59 / 40 0 0 0 0
BROWNFIELD 63 33 62 31 59 / 50 0 0 0 0
CHILDRESS 62 40 65 34 61 / 60 20 0 0 0
SPUR 62 38 65 34 64 / 50 10 0 0 0
ASPERMONT 64 41 68 38 66 / 30 20 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING FROM 2 PM THIS AFTERNOON TO 6 PM CST THIS
EVENING FOR THE FOLLOWING ZONES:
TXZ021>023-027>029-033>035-039>041.
&&
$$
31
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
554 AM CST FRI DEC 14 2012
.AVIATION...
STRATUS...STRONG TSRA...HIGH WINDS...AND BLOWING DUST WILL MAKE
FOR DETERIORATING CONDITIONS TODAY. HIGH CONFIDENCE THAT MORNING
MVFR STRATUS WILL REMAIN LARGELY UNDISTURBED THROUGH EARLY
AFTERNOON. THIS LAYER MAY OCCASIONALLY DROP TO HIGH-END IFR
LEVELS BEFORE 16Z AT LBB...BUT A MUCH BETTER CHANCE OF IFR
CONDITIONS AT LBB WILL ACCOMPANY A FAST-MOVING COLD FRONT AROUND
22Z AS 30-40 KNOT SWLY WINDS REDUCE VISBYS TO 1SM OR LESS IN BLDU.
CDS SHOULD ESCAPE THESE EFFECTS...HOWEVER BOTH TERMINALS WILL
LIKELY SEE A BROKEN LINE OF TSRA ACCOMPANY THE FRONT COMPLETE WITH
LOCALLY DMGG WINDS. SUSPENDED DUST MAY LINGER FOR A FEW HOURS AT LBB
AFTER SUNSET WHEN WINDS SUBSIDE...BUT AS A WHOLE VFR CONDITIONS
SHOULD EMERGE BY EARLY EVENING AT BOTH STATIONS.
&&
.PREV DISCUSSION... /ISSUED 501 AM CST FRI DEC 14 2012/
SHORT TERM...
MULTI-FACETED AND EXCEPTIONALLY ACTIVE WEATHER FOR MID-DECEMBER
AWAITS THE SOUTH PLAINS LATER TODAY AS A VIGOROUS UPPER LOW LIFTS
NORTHEAST FROM NORTHERN BAJA IN THE FORM OF A NEGATIVELY TILTED
TROUGH. EARLY MORNING WATER VAPOR DEPICTION OF SAID LOW WAS QUITE
IMPRESSIVE AND FEATURED A DEEPENING PLUME OF SUBTROPICAL MOISTURE
AND SOME THUNDERSTORMS WELL IN ITS ADVANCE. ABUNDANT LOW-LEVEL
MOISTURE ADVECTION CONTINUED OVER WEST TX THIS MORNING AND WILL
ONLY CONTINUE THROUGH 18Z AS RESPECTABLE PRESSURE FALLS AROUND
7MB/6HR FOCUS IN ERN NM AHEAD OF THE EJECTING WAVE. THIS WILL KEEP
MOIST SOUTHERLY WINDS...STRATUS AND SOME FOG INTACT LONGER THAN
ORIGINALLY FORECAST BEFORE STRONG HEIGHT FALLS /60+ METERS AT
500MB/ UNFOLD BY EARLY AFTN ALONG THE NM-TX STATE LINE. ALONG WITH
A 135 KNOT UPPER SPEED MAX...A PACIFIC FRONT ACCOMPANYING THE
LEADING EDGE OF HEIGHT FALLS SHOULD EASILY SECURE DEEP ASCENT
WHILE PUTTING OUR SEASONABLY HIGH DEWPOINTS TO WORK.
CONSIDERING THE FLOW AHEAD OF THIS TROUGH IS MORE MERIDIONAL THAN
MODELS INDICATED JUST A FEW DAYS AGO...THE CHANCES OF A DRY FROPA
HAVE NOW GREATLY DIMINISHED. AFTERNOON POPS WERE DOUBLED NEARLY
AREA WIDE WITH JUST SLIGHT CHANCES OF MRNG SHOWERS CONFINED MAINLY
OFF THE CAPROCK WHERE DEEPER MOIST ADVECTION WITHIN A LLJ AXIS
COULD FAVOR VERY LIGHT PRECIP.
ALTHOUGH STRATUS WILL BE VERY SLOW TO ERODE...AMPLE MID-LEVEL
COOLING ACCOMPANYING THE UPPER TROUGH IS STILL SHOWN TO GARNER
WEAK SBCAPE AOB 600 J/KG BY 21Z WITH SURFACE TEMPS IN THE 50S-
60S. IT IS NOT UNCOMMON TO SEE SOME SEVERE CONVECTIVE MODES UNFOLD
IN SUCH LOW CAPE AND HIGH SHEAR ENVIRONMENTS PROVIDED
STRONG/FOCUSED ASCENT EMERGES. INITIAL SWODY1 ACCOUNTS FOR THIS
SCENARIO AND SEVERAL HI RES MODELS INCLUDING THE TTU-WRF DEPICT A
BROKEN LINE OF PARTICULARLY STRONG CELLS ACCOMPANYING FROPA. SUCH
A SCENARIO INVOLVING DMGG DOWNBURST WINDS OCCURRED HERE IN MID
DECEMBER 1993 FROM A SIMILAR SYNOPTIC PATTERN. AS WAS THE CASE
THEN...SEVERE WIND GUSTS WOULD BE THE DOMINANT THREAT WITH STORMS
TODAY AS STRONG KINEMATIC FLOW OVERSPREADS THE REGION. VERY MEAGER
CAPE IN THE HAIL GROWTH REGION SHOULD KEEP SEVERE HAIL PRODUCTION
AT BAY.
IN ADDITION TO A THREAT OF SEVERE CONVECTIVE WINDS...PATTERN
RECOGNITION BEHIND THE FRONT BY MID/LATE AFTERNOON DOES FAVOR AN
ABBREVIATED NON-CONVECTIVE HIGH WIND EVENT. A 500MB WIND MAX OF 100
KNOTS IS PROGGED TO OVERSPREAD OUR SWRN COUNTIES BY 21Z COMPLETE
WITH 60-70 KNOTS AT THE TOP OF THE MIXING LAYER AROUND 700MB OVER
MUCH OF THE CAPROCK. STRONG POST-FRONTAL SUBSIDENCE AND DRYING ON
SWLY WINDS SHOULD ALLOW FOR AN ABBREVIATED WINDOW OF 40G58 MPH
CONDITIONS OR HIGHER IMMEDIATELY FOLLOWING THE PACIFIC FRONT UNTIL
BOUNDARY LAYER DECOUPLING ENSUES BY 00Z. MOS GUIDANCE IS WELL
SHORT OF HIGH WIND CRITERIA...BUT WE BELIEVE MUCH OF THIS IS DUE
TO THE RELATIVELY SHORT DURATION OF HIGH WINDS THAT WE ANTICIPATE
WILL DEVELOP LATE IN THE DAY. TTU-WRF AND HRRR CONTINUE TO
CHAMPION SUCH CONDITIONS FOR A FEW HOURS FOLLOWING FROPA WITH
GUSTS AROUND 60 MPH TAKING AIM MAINLY WEST OF I-27.
LONG TERM...
ALTHOUGH WIND SPEEDS WILL DECREASE A BIT TONIGHT INTO SATURDAY
MORNING...EXPECT THEM TO ONCE AGAIN RAMP UP SOME SATURDAY
AFTERNOON AS ANOTHER APPROACHING SHORTWAVE TROF KEEPS A TIGHT
PRESSURE GRADIENT OVER THE REGION. SOIL WILL HAVE DRIED OUT SOME
FROM ANY RAINFALL TODAY AND CONDITIONS WILL ONCE AGAIN FAVOR SOME
AREAS OF BLOWING DUST SATURDAY AFTERNOON. THIS STORM SYSTEM WILL
RAPIDLY PUSH EAST SATURDAY NIGHT BEFORE ANOTHER TROF PUSHES OVER
THE AREA FOR SUNDAY AFTERNOON. THIS THIRD STORM SYSTEM WILL NOT BE
QUITE AS STRONG BUT WILL LIKELY RESULT IN BREEZY CONDITIONS AGAIN
FOR SUNDAY AFTERNOON. THROUGH THE WEEKEND...TEMPERATURES WILL ALSO
SLOWLY COOL AS CONTINUED COLD AIR ADVECTION TAKES PLACE KEEPING
READINGS CLOSE TO NORMAL FOR THIS TIME OF YEAR.
DRY WEATHER WILL BE EXPECTED FOR THE FIRST PART OF NEXT WEEK AS
DRY NORTHWESTERLY FLOW GRADUALLY TRANSITIONS TO SOUTHWESTERLY BY
MID-WEEK. THIS WILL ALLOW TEMPERATURES TO ONCE AGAIN CLIMB TO
ABOVE NORMAL THROUGH WEDNESDAY. ALSO BY MID-WEEK...ANOTHER
CANADIAN COLD FRONT WILL PUSH SOUTH THROUGH THE CENTRAL PLAINS
AND ARRIVE SOMETIME LATE WEDNESDAY INTO THURSDAY MORNING. THIS
FRONTAL PASSAGE SHOULD BE DRY AS LITTLE MOISTURE RECOVERY TAKES
PLACE BEFORE IT MOVES THROUGH. THIS FRONT WILL DROP TEMPERATURES
BACK DOWN TO NORMAL FOR THE END OF THE WEEK.
JORDAN
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 58 30 57 26 55 / 60 0 0 0 0
TULIA 60 33 59 28 55 / 60 0 0 0 0
PLAINVIEW 60 33 59 28 55 / 60 0 0 0 0
LEVELLAND 62 32 60 30 57 / 60 0 0 0 0
LUBBOCK 62 34 61 31 57 / 60 0 0 0 0
DENVER CITY 62 31 62 32 59 / 40 0 0 0 0
BROWNFIELD 63 33 62 31 59 / 50 0 0 0 0
CHILDRESS 62 40 65 34 61 / 60 20 0 0 0
SPUR 62 38 65 34 64 / 50 10 0 0 0
ASPERMONT 64 41 68 38 66 / 30 20 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING FROM 2 PM THIS AFTERNOON TO 6 PM CST THIS
EVENING FOR THE FOLLOWING ZONES:
TXZ021>023-027>029-033>035-039>041.
&&
$$
93
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
501 AM CST FRI DEC 14 2012
.SHORT TERM...
MULTI-FACETED AND EXCEPTIONALLY ACTIVE WEATHER FOR MID-DECEMBER
AWAITS THE SOUTH PLAINS LATER TODAY AS A VIGOROUS UPPER LOW LIFTS
NORTHEAST FROM NORTHERN BAJA IN THE FORM OF A NEGATIVELY TILTED
TROUGH. EARLY MORNING WATER VAPOR DEPICTION OF SAID LOW WAS QUITE
IMPRESSIVE AND FEATURED A DEEPENING PLUME OF SUBTROPICAL MOISTURE
AND SOME THUNDERSTORMS WELL IN ITS ADVANCE. ABUNDANT LOW-LEVEL
MOISTURE ADVECTION CONTINUED OVER WEST TX THIS MORNING AND WILL
ONLY CONTINUE THROUGH 18Z AS RESPECTABLE PRESSURE FALLS AROUND
7MB/6HR FOCUS IN ERN NM AHEAD OF THE EJECTING WAVE. THIS WILL KEEP
MOIST SOUTHERLY WINDS...STRATUS AND SOME FOG INTACT LONGER THAN
ORIGINALLY FORECAST BEFORE STRONG HEIGHT FALLS /60+ METERS AT
500MB/ UNFOLD BY EARLY AFTN ALONG THE NM-TX STATE LINE. ALONG WITH
A 135 KNOT UPPER SPEED MAX...A PACIFIC FRONT ACCOMPANYING THE
LEADING EDGE OF HEIGHT FALLS SHOULD EASILY SECURE DEEP ASCENT
WHILE PUTTING OUR SEASONABLY HIGH DEWPOINTS TO WORK.
CONSIDERING THE FLOW AHEAD OF THIS TROUGH IS MORE MERIDIONAL THAN
MODELS INDICATED JUST A FEW DAYS AGO...THE CHANCES OF A DRY FROPA
HAVE NOW GREATLY DIMINISHED. AFTERNOON POPS WERE DOUBLED NEARLY
AREA WIDE WITH JUST SLIGHT CHANCES OF MRNG SHOWERS CONFINED MAINLY
OFF THE CAPROCK WHERE DEEPER MOIST ADVECTION WITHIN A LLJ AXIS
COULD FAVOR VERY LIGHT PRECIP.
ALTHOUGH STRATUS WILL BE VERY SLOW TO ERODE...AMPLE MID-LEVEL
COOLING ACCOMPANYING THE UPPER TROUGH IS STILL SHOWN TO GARNER
WEAK SBCAPE AOB 600 J/KG BY 21Z WITH SURFACE TEMPS IN THE 50S-
60S. IT IS NOT UNCOMMON TO SEE SOME SEVERE CONVECTIVE MODES UNFOLD
IN SUCH LOW CAPE AND HIGH SHEAR ENVIRONMENTS PROVIDED
STRONG/FOCUSED ASCENT EMERGES. INITIAL SWODY1 ACCOUNTS FOR THIS
SCENARIO AND SEVERAL HI RES MODELS INCLUDING THE TTU-WRF DEPICT A
BROKEN LINE OF PARTICULARLY STRONG CELLS ACCOMPANYING FROPA. SUCH
A SCENARIO INVOLVING DMGG DOWNBURST WINDS OCCURRED HERE IN MID
DECEMBER 1993 FROM A SIMILAR SYNOPTIC PATTERN. AS WAS THE CASE
THEN...SEVERE WIND GUSTS WOULD BE THE DOMINANT THREAT WITH STORMS
TODAY AS STRONG KINEMATIC FLOW OVERSPREADS THE REGION. VERY MEAGER
CAPE IN THE HAIL GROWTH REGION SHOULD KEEP SEVERE HAIL PRODUCTION
AT BAY.
IN ADDITION TO A THREAT OF SEVERE CONVECTIVE WINDS...PATTERN
RECOGNITION BEHIND THE FRONT BY MID/LATE AFTERNOON DOES FAVOR AN
ABBREVIATED NON-CONVECTIVE HIGH WIND EVENT. A 500MB WIND MAX OF 100
KNOTS IS PROGGED TO OVERSPREAD OUR SWRN COUNTIES BY 21Z COMPLETE
WITH 60-70 KNOTS AT THE TOP OF THE MIXING LAYER AROUND 700MB OVER
MUCH OF THE CAPROCK. STRONG POST-FRONTAL SUBSIDENCE AND DRYING ON
SWLY WINDS SHOULD ALLOW FOR AN ABBREVIATED WINDOW OF 40G58 MPH
CONDITIONS OR HIGHER IMMEDIATELY FOLLOWING THE PACIFIC FRONT UNTIL
BOUNDARY LAYER DECOUPLING ENSUES BY 00Z. MOS GUIDANCE IS WELL
SHORT OF HIGH WIND CRITERIA...BUT WE BELIEVE MUCH OF THIS IS DUE
TO THE RELATIVELY SHORT DURATION OF HIGH WINDS THAT WE ANTICIPATE
WILL DEVELOP LATE IN THE DAY. TTU-WRF AND HRRR CONTINUE TO
CHAMPION SUCH CONDITIONS FOR A FEW HOURS FOLLOWING FROPA WITH
GUSTS AROUND 60 MPH TAKING AIM MAINLY WEST OF I-27.
&&
.LONG TERM...
ALTHOUGH WIND SPEEDS WILL DECREASE A BIT TONIGHT INTO SATURDAY
MORNING...EXPECT THEM TO ONCE AGAIN RAMP UP SOME SATURDAY
AFTERNOON AS ANOTHER APPROACHING SHORTWAVE TROF KEEPS A TIGHT
PRESSURE GRADIENT OVER THE REGION. SOIL WILL HAVE DRIED OUT SOME
FROM ANY RAINFALL TODAY AND CONDITIONS WILL ONCE AGAIN FAVOR SOME
AREAS OF BLOWING DUST SATURDAY AFTERNOON. THIS STORM SYSTEM WILL
RAPIDLY PUSH EAST SATURDAY NIGHT BEFORE ANOTHER TROF PUSHES OVER
THE AREA FOR SUNDAY AFTERNOON. THIS THIRD STORM SYSTEM WILL NOT BE
QUITE AS STRONG BUT WILL LIKELY RESULT IN BREEZY CONDITIONS AGAIN
FOR SUNDAY AFTERNOON. THROUGH THE WEEKEND...TEMPERATURES WILL ALSO
SLOWLY COOL AS CONTINUED COLD AIR ADVECTION TAKES PLACE KEEPING
READINGS CLOSE TO NORMAL FOR THIS TIME OF YEAR.
DRY WEATHER WILL BE EXPECTED FOR THE FIRST PART OF NEXT WEEK AS
DRY NORTHWESTERLY FLOW GRADUALLY TRANSITIONS TO SOUTHWESTERLY BY
MID-WEEK. THIS WILL ALLOW TEMPERATURES TO ONCE AGAIN CLIMB TO
ABOVE NORMAL THROUGH WEDNESDAY. ALSO BY MID-WEEK...ANOTHER
CANADIAN COLD FRONT WILL PUSH SOUTH THROUGH THE CENTRAL PLAINS
AND ARRIVE SOMETIME LATE WEDNESDAY INTO THURSDAY MORNING. THIS
FRONTAL PASSAGE SHOULD BE DRY AS LITTLE MOISTURE RECOVERY TAKES
PLACE BEFORE IT MOVES THROUGH. THIS FRONT WILL DROP TEMPERATURES
BACK DOWN TO NORMAL FOR THE END OF THE WEEK.
JORDAN
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 58 30 57 26 55 / 60 0 0 0 0
TULIA 60 33 59 28 55 / 60 0 0 0 0
PLAINVIEW 60 33 59 28 55 / 60 0 0 0 0
LEVELLAND 62 32 60 30 57 / 60 0 0 0 0
LUBBOCK 62 34 61 31 57 / 60 0 0 0 0
DENVER CITY 62 31 62 32 59 / 40 0 0 0 0
BROWNFIELD 63 33 62 31 59 / 50 0 0 0 0
CHILDRESS 62 40 65 34 61 / 60 20 0 0 0
SPUR 62 38 65 34 64 / 50 10 0 0 0
ASPERMONT 64 41 68 38 66 / 30 20 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING FROM 2 PM THIS AFTERNOON TO 6 PM CST THIS
EVENING FOR THE FOLLOWING ZONES:
TXZ021>023-027>029-033>035-039>041.
&&
$$
93/14
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
317 AM CST FRI DEC 14 2012
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
317 AM CST FRI DEC 14 2012
THE MAIN FOCUS THROUGH THE WEEKEND IS WITH THE SYSTEM MOVING IN
TONIGHT THAT WILL LINGER THROUGH MUCH OF THE WEEKEND WITH THE
QUESTION BEING WHAT TYPE OF PRECIPITATION WILL FALL AS IT MOVES
THROUGH.
MAINLY ZONAL FLOW ALOFT IS IN PLACE THROUGH THE EASTERN HALF OF
THE US WHILE A CLOSED LOW MOVES INTO THE FOUR CORNERS REGION. AT
THE SURFACE...A RIDGE OF HIGH PRESSURE EXTENDS SOUTH FROM HUDSON
BAY THROUGH LAKE SUPERIOR AND THE UPPER MISSISSIPPI RIVER VALLEY.
A BAND OF CIRRUS HAS MOVED THROUGH ALONG THE RIGHT ENTRANCE REGION
OF THE UPPER LEVEL JET WHILE A BAND OF STRATUS/FOG HAS DROPPED
SOUTH OUT OF LAKE SUPERIOR AHEAD OF THE SURFACE RIDGE AXIS.
VISIBILITY HAS MAINLY BEEN ABOVE 2SM WITH THIS FOG...THOUGH ON THE
LEADING EDGE THERE HAS BEEN SOME PATCHY DENSE FOG THAT HAS FORMED.
TEMPERATURES ARE IN THE 20-28F RANGE IN THIS AREA...SO SOME SLICK
SPOTS WILL BE POSSIBLE THIS MORNING UNDER THIS FOG...THOUGH TAYLOR
COUNTY SHERIFF HAD REPORTED THAT THEY HAVE NOT HEARD OF ANY ISSUES
AS OF 2AM. WITH THE PRESSURE GRADIENT TIGHTENING TODAY AND THE
TROUGH EJECTING INTO THE CENTRAL PLAINS...SHOULD HAVE JUST HIGH
LEVEL CLOUD COVER TO CONTEND WITH AND TEMPERATURES CLIMBING INTO
THE 40S.
THE CLOSED MID LEVEL AND SURFACE LOW WILL MAKE THEIR WAY THROUGH
THE CENTRAL PLAINS TODAY INTO TONIGHT WITH PRECIPITATION MOVING
NORTH AND REACHING NORTHEAST IOWA AROUND OR JUST AFTER MIDNIGHT.
THE 14.00Z NAM/HI-RES ARW/NMM ARE A TAD SLOWER WITH THE
PROPAGATION NORTHEASTWARD OF THE PRECIPITATION BAND OVERNIGHT
COMPARED TO THE 14.00Z GFS/ECMWF/GEM...SO HAVE TRENDED A LITTLE
SLOWER WITH THE PRECIPITATION MOVING IN. THE INITIAL QUESTION IS
WITH SURFACE TEMPERATURES AND WHETHER THEY WILL BE AT OR BELOW
FREEZING AS THIS PRECIPITATION MOVES IN SINCE IT WILL BE RAIN THAT
FALLS THROUGH DAY BREAK WITH A LOW LEVEL WARM LAYER PUSHING +6C
REGION-WIDE. WITH THE LOW LEVEL FLOW STAYING OUT OF THE
SOUTH...THE MAIN AREA OF CONCERN APPEARS TO BE IN NORTH CENTRAL
WISCONSIN WHERE THE SNOW PACK IS A LITTLE DEEPER AND COULD KEEP
TEMPERATURES AROUND FREEZING. EVEN SO...AS THE RAIN BEGINS THE
LATENT HEAT RELEASE SHOULD PUSH SURFACE TEMPERATURES UP A FEW
DEGREES...LIKELY BACK ABOVE FREEZING. HAVE BACKED OFF A BIT ON THE
FREEZING RAIN POTENTIAL AS A RESULT.
THE NEXT QUESTION IS WITH SATURDAY MORNING WITH WHETHER OR NOT
THERE WILL BE A PERIOD OF SNOW ACROSS SOUTHEAST MINNESOTA AND
WESTERN WISCONSIN. THE 14.00Z GFS IS THE WARMEST SOLUTION AND
SUGGEST THAT P-TYPE WILL REMAIN ALL RAIN IN THE MORNING...BUT THE
14.00Z NAM/HI-RES ARW/NMM RUNS SHOW THAT AS THE PRECIPITATION
STARTS TO FALL IT WILL COOL DOWN THE WARM LAYER TO THE WET BULB
TEMPERATURE...WHICH IS RIGHT AROUND 0C. SHOULD THIS HAPPEN...THE
THERMAL PROFILE WOULD SUGGEST THAT SNOW WOULD FALL UNTIL WARMER
LOW LEVEL AIR MOVES IN LATER IN THE MORNING AS THE SURFACE/LOW
LEVEL LOW MOVES IN. HAVE ADDED SOME CHANCES FOR LIGHT SNOW IN
THERE WITH MINOR ACCUMULATIONS IN THE MORNING WITH THE HIGHEST
AMOUNTS FALLING IN NORTH CENTRAL WISCONSIN IN THE 1-3 INCH RANGE.
AFTER THE DEEP FORCING WANES IN THE AFTERNOON/EVENING
SATURDAY...THERE COULD BE A PERIOD OF DRIZZLE THAT OCCURS WITH THE
COLUMN LOSING ICE GENERATIONS...THOUGH TEMPERATURES SHOULD BE
WARM ENOUGH INITIALLY FOR IT NOT TO FREEZE. WILL HAVE TO WATCH THE
PERIOD AS THE RAIN TRANSITIONS TO SNOW AND WHETHER THERE WOULD BE
ANY FREEZING DRIZZLE THAT MIXES IN BETWEEN THE PRECIPITATION
PERIODS. CONFIDENCE IS NOT HIGH ENOUGH AT THIS POINT TO INTRODUCE
THE DRIZZLE...SO HAVE JUST LEFT IT AS A TRANSITION FROM RAIN TO
SNOW. THE SURFACE LOW WILL THEN SLOWLY TRACK TO THE EAST TOWARD
LAKE MICHIGAN ON SUNDAY WITH SOME LIGHT PRECIPITATION POSSIBLY
LINGERING AS WELL.
.LONG TERM...MONDAY THROUGH THURSDAY
317 AM CST FRI DEC 14 2012
THE EXTENDED PERIOD WILL START OUT ON THE BACK SIDE OF THE WEEKEND
SYSTEM WITH NORTHWESTERLY FLOW IN PLACE FROM THE SURFACE AND
ALOFT. A TRAILING SHORTWAVE TROUGH COULD LEAD TO SOME LIGHT SNOW
IN WISCONSIN ON MONDAY..BUT THE OVERALL FORCING BETWEEN THE 14.00Z
GFS/ECMWF IS RATHER WEAK AND BETTER TO THE EAST...SO AM NOT
EXPECTING MUCH OUT OF THIS FEATURE.
THE COOL LOW LEVEL AIR MASS WILL PROPAGATE EASTWARD ON TUESDAY AS
THE NEXT TROUGH MOVES INTO THE NORTHERN PLAINS ON WEDNESDAY.
WARMER LOW LEVEL AIR WILL START NOSING UP INTO THE REGION ON
TUESDAY/TUESDAY NIGHT WITH THE 14.00Z ECMWF/GEM SUGGESTING THAT
SOME PRECIPITATION COULD FORM ALONG THIS LOW LEVEL TEMPERATURE
GRADIENT. CONFIDENCE NOT HIGH ENOUGH TO PUT IT IN THE FORECAST
RIGHT NOW...BUT WILL HAVE TO MONITOR TRENDS WITH THIS FEATURE.
SOME DIFFERENCES CONTINUE BETWEEN THE 14.00Z GFS/ECMWF/GEM ON
WEDNESDAY WITH THE POSITION OF THE SURFACE LOW WITH THE GFS
APPEARING TO BE A FAST OUTLIER WITH THE LOW BEING INTO CENTRAL
IOWA WHILE THE ECMWF/GEM HAVE THE LOW IN WESTERN KANSAS. DESPITE
THE DIFFERENCES IN TIMING/PLACEMENT OF THE LOW...THE TIMING IS NOT
TOO FAR OFF WITH THE PRECIPITATION MOVING IN ON WEDNESDAY NIGHT
INTO THURSDAY. THE GFS DOES LOOK A TAD COOLER WITH ITS THERMAL
PROFILE AND WOULD MEAN MORE OF A SNOW EVENT WHERE THE ECMWF WOULD
SUGGEST MORE RAIN WITH A WARMER NEAR SURFACE LAYER. WILL HAVE TO
IRON OUT THOSE DETAILS AS WE GET CLOSER...BUT BASED ON THESE
THERMAL PROFILES LOOKING MORE LIKELY TO PRODUCE SNOW...HAVE JUST
LEFT THE PRECIPITATION TYPE AS ALL SNOW OVER THIS TIME PERIOD.
ANOTHER SHOT OF COLD AIR FOLLOWS THIS SYSTEM WITH 850MB
TEMPERATURES LIKELY DROPPING BACK DOWN TO AROUND -10C BY FRIDAY.
&&
.AVIATION...THROUGH 06Z SATURDAY
1131 PM CST THU DEC 13 2012
AT 05Z HIGH PRESSURE WAS CENTERED OVER CENTRAL MINNESOTA...WHERE
SKIES WERE CLEAR. FOG AND SOME STRATUS HAD FORMED ON THE SOUTHERN
EDGE OF THE HIGH FROM CENTRAL MINNESOTA INTO NORTH CENTRAL
WISCONSIN. NEAR TERM CONCERNS REMAIN ON FOG/STRATUS POTENTIAL
THROUGH THE OVERNIGHT HOURS. 14.03Z RAP SOUNDINGS CONTINUE TO
INDICATE LOW LEVEL SATURATION REMAINS NORTH OF THE TAF SITES AND
THUS EXPECT THE LOWEST VISIBILITIES IN THESE AREAS. 14.00Z NAM HAS
ALSO BACKED AWAY FROM THE BOUNDARY LAYER SATURATION AT KLSE AND
KRST. GIVEN CURRENT TEMPERATURES/DEW POINT SPREADS OF 2 TO 3
DEGREES AT KLSE AND KRST DO FEEL SOME FOG IS LIKELY AT THE TAF
SITES...MAINLY IN THE MVFR CATEGORY AND WILL USE A TEMPO GROUP FOR
IFR CONDITIONS BETWEEN 08Z-12Z. PRESSURE GRADIENT DOES TIGHTEN BY
MID MORNING AND SHOULD SCOUR OUT ANY REMAINING STRATUS AND FOG
WITH VFR CONDITIONS THROUGH AT LEAST 02Z. BETWEEN 02Z-06Z AN AREA
OF LOW PRESSURE WILL LIFT OUT OF THE PLAINS TOWARDS THE AREA. AT
THIS TIME IT LOOKS LIKE ANY PRECIPITATION AT THE SITES WILL BE
AFTER 06Z...WITH JUST LOWERING CEILINGS IN THE 02Z-06Z TIME
FRAME...POSSIBLY INTO MVFR BY 06Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
317 AM CST FRI DEC 14 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1131 PM CST THU DEC 13 2012
.SHORT TERM...TONIGHT THROUGH SUNDAY
323 PM CST THU DEC 13 2012
MAIN FORECAST CONCERNS ARE PRECIPITATION TYPES FRIDAY NIGHT INTO
SATURDAY.
LATEST WATER VAPOR SATELLITE IMAGERY SHOWING UPPER LEVEL TROUGH/LOW
OVER SOUTHWESTERN UNITED STATES AND WEST TO EAST ZONAL FLOW OVER
UPPER MIDWEST AND GREAT LAKES REGION. LATEST 20Z SURFACE ANALYSIS
INDICATES COLD FRONT EXTENDING OVER LAKE SUPERIOR TO WESTERN IOWA.
LATEST METARS OUT AHEAD OF THE FRONT SHOW TEMPERATURES IN THE LOWER
40S TO LOWER 50S AND BEHIND THE FRONT TEMPERATURES IN THE TEENS TO
MIDDLE 20S.
THE LATEST 13.12Z NAM IS SLIGHTLY MORE PROGRESSIVE WITH
SURFACE/UPPER LEVEL LOW EJECTING OUT INTO THE UPPER MIDWEST AND
GREAT LAKES REGION FRIDAY NIGHT INTO SATURDAY...THAN THE 13.12Z GFS.
HOWEVER...THE 13.12Z NAM DPROG/DT SHOWS SLIGHTLY SLOWER MOVEMENT AND
THE 13.12Z GFS DPROG/DT INDICATES BETTER RUN TO RUN CONSISTENCY THE
PAST FEW RUNS. THE DETERMINISTIC 13.12Z GFS/NAM ARE IN AGREEMENT
WARMER AIR ALOFT WILL ADVECT INTO THE AREA OUT AHEAD OF UPPER
LEVEL/SURFACE LOW AND PROVIDE POTENTIAL PROBLEMS FOR PRECIPITATION
TYPES ESPECIALLY OVER PORTIONS OF THE NORTHERN HALF OF THE FORECAST
AREA. CONFIDENCE IS LOW ON EXACT TIMING AND PLACEMENT OF
PRECIPITATION TYPES AND FRIDAY NIGHT INTO SATURDAY...OVERALL
CONFIDENCE IS INCREASING PARTS OF THE REGION WILL SEE SOME WINTRY
MIX OF PRECIPITATION LATE FRIDAY NIGHT INTO SATURDAY.
TONIGHT...WEAK COLD FRONT PUSHES SLOWLY INTO EASTERN WISCONSIN AND
EASTERN IOWA. A RELAXED PRESSURE GRADIENT WILL PRODUCE LIGHT WINDS
ACROSS FORECAST AREA...AS 13.12Z NAM/GFS BUFKIT SOUNDINGS SHOW LESS
THAN 10 KNOTS UP TO 3000 FEET ACROSS MUCH OF THE FORECAST AREA.
THE COMBINATION OF MELTING SNOW AND LIGHT WINDS WILL SATURATE THE
NEAR SURFACE BOUNDARY LAYER AND CAUSE LOW STRATUS DECK OR AREAS OF
FOG TO DEVELOP AFTER SUNSET. BIG QUESTION WILL BE HOW WIDESPREAD
AND DENSE FOG WILL BE. FOR NOW...HAVE CONTINUED PREVIOUS FORECAST OF
AREAS OF FOG AND INCREASED SKY COVER...ESPECIALLY OVER THE NORTHERN
HALF OF THE FORECAST AREA.
NEXT CONCERN IS POTENTIAL FOR PRECIPITATION TYPE FRIDAY NIGHT INTO
SATURDAY. THE DETERMINISTIC 13.12Z GFS/NAM ARE BOTH INDICATING WARMER
AIR ADVECTING NORTHWARD AHEAD OF THE SURFACE/UPPER LEVEL LOW INTO
THE REGION AND ARE IN OKAY AGREEMENT WITH THE PLACEMENT OF THE
SURFACE LOW...HOWEVER TIMING OF SURFACE LOW IS IN QUESTION. THE
DETERMINISTIC MODELS ARE INDICATING STRONG VERTICAL MOTION AND
ISENTROPIC LIFT IN ASSOCIATION WITH THE SURFACE/UPPER LEVEL LOW PER
CROSS SECTIONS. BUFKIT SOUNDINGS FROM BOTH THE NAM AND GFS SHOW MAX
TEMPERATURE ALOFT TO BE PLUS 4 TO 7 DEGREES CELSIUS BY 06Z SATURDAY
ACROSS MUCH OF THE FORECAST AREA. THE BUFKIT SOUNDINGS INDICATE
DIABATIC COOLING THROUGH THE ATMOSPHERE COLUMN FROM 06Z TO 12Z
SATURDAY...AS BETTER LIFT AND VERTICAL MOTION PUSHES ACROSS THE
NORTHERN HALF OF THE FORECAST AREA...ESPECIALLY OVER SOUTHEAST
MINNESOTA. THIS ALLOWS TEMPERATURES ALOFT TO COOL DOWN TO NEAR
FREEZING AND CAUSE THE POTENTIAL FOR THE PRECIPITATION TO MIX IN WITH
SNOW OR BE ALL SNOW OVER HIGHER TERRAIN AREAS OF SOUTHERN MINNESOTA
AND WESTERN WISCONSIN BY 12Z SATURDAY. HAVE INTRODUCED A RAIN SNOW
MIX OVER PARTS OF SOUTHEAST MINNESOTA SATURDAY MORNING...BASED ON
THIS. NORTH CENTRAL WISCONSIN WILL CONTINUE TO HAVE THE POTENTIAL TO
SEE A WINTRY MIX OF SNOW...SLEET...RAIN...AND POSSIBLY FREEZING RAIN
LATE FRIDAY NIGHT INTO SATURDAY. BUFKIT SOUNDINGS IN THIS AREA
SHOW COLDER TEMPERATURES ALOFT AND THE POTENTIAL FOR ALL SNOW WITH
SNOW ACCUMULATION OF 2 TO 4 INCHES AND LESS THAN A TENTH OF AN INCH
OF ICE ACCUMULATION. ALL RAIN SHOULD BE DOMINATE ACROSS PORTIONS OF
NORTHEAST IOWA AND EXTREME SOUTHERN WISCONSIN.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
323 PM CST THU DEC 13 2012
MAIN FORECAST CONCERNS IS PRECIPITATION CHANCES SUNDAY NIGHT...THEN
AGAIN WEDNESDAY INTO THURSDAY. THE 13.00Z GFS/ECMWF/GEM ARE
IN AGREEMENT WITH THE REGION REMAINING UNDER THE INFLUENCE OF THE
UPPER LEVEL/SURFACE LOW OVER THE GREAT LAKES REGION SUNDAY NIGHT INTO
MONDAY. THIS WILL CONTINUE TO WRAP THE POSSIBILITY OF LIGHT SNOW OR
FLURRIES INTO THE EASTERN PARTS OF THE FORECAST AREA SUNDAY NIGHT
INTO MONDAY. THE DETERMINISTIC MODELS THEN BEGIN TO DIVERGE ON
TUESDAY WITH THE 13.00Z GEM MORE PROGRESSIVE IN DIGGING UPPER LEVEL
TROUGH AND DEVELOPING SURFACE LOW OVER CENTRAL PLAINS THAN THE 13.00Z
ECMWF/GFS. AT THIS TIME...WILL KEEP FORECAST AREA MAINLY DRY...AS THE
13.00Z GEFS SHOW UPPER LEVEL TROUGH FARTHER NORTH AND A SLOWER
SOLUTION. NEXT CONCERN IS THE 13.00Z GFS/ECMWF DIG UPPER LEVEL TROUGH
OVER THE UPPER MIDWEST AND GREAT LAKES REGION WEDNESDAY INTO
THURSDAY...HOWEVER BOTH THE MODELS DIFFER ON PLACEMENT AND TIMING OF
SURFACE LOW. THE DETERMINISTIC 13.00Z GFS/ECMWF INDICATE ENOUGH LIFT
AND SATURATION ASSOCIATED WITH UPPER LEVEL TROUGH/SURFACE LOW AND
WILL INTRODUCE SMALL PRECIPITATION CHANCES ACROSS FORECAST AREA.
&&
.AVIATION...THROUGH 06Z SATURDAY
1131 PM CST THU DEC 13 2012
AT 05Z HIGH PRESSURE WAS CENTERED OVER CENTRAL MINNESOTA...WHERE
SKIES WERE CLEAR. FOG AND SOME STRATUS HAD FORMED ON THE SOUTHERN
EDGE OF THE HIGH FROM CENTRAL MINNESOTA INTO NORTH CENTRAL
WISCONSIN. NEAR TERM CONCERNS REMAIN ON FOG/STRATUS POTENTIAL
THROUGH THE OVERNIGHT HOURS. 14.03Z RAP SOUNDINGS CONTINUE TO
INDICATE LOW LEVEL SATURATION REMAINS NORTH OF THE TAF SITES AND
THUS EXPECT THE LOWEST VISIBILITIES IN THESE AREAS. 14.00Z NAM HAS
ALSO BACKED AWAY FROM THE BOUNDARY LAYER SATURATION AT KLSE AND
KRST. GIVEN CURRENT TEMPERATURES/DEW POINT SPREADS OF 2 TO 3
DEGREES AT KLSE AND KRST DO FEEL SOME FOG IS LIKELY AT THE TAF
SITES...MAINLY IN THE MVFR CATEGORY AND WILL USE A TEMPO GROUP FOR
IFR CONDITIONS BETWEEN 08Z-12Z. PRESSURE GRADIENT DOES TIGHTEN BY
MID MORNING AND SHOULD SCOUR OUT ANY REMAINING STRATUS AND FOG
WITH VFR CONDITIONS THROUGH AT LEAST 02Z. BETWEEN 02Z-06Z AN AREA
OF LOW PRESSURE WILL LIFT OUT OF THE PLAINS TOWARDS THE AREA. AT
THIS TIME IT LOOKS LIKE ANY PRECIPITATION AT THE SITES WILL BE
AFTER 06Z...WITH JUST LOWERING CEILINGS IN THE 02Z-06Z TIME
FRAME...POSSIBLY INTO MVFR BY 06Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
323 PM CST THU DEC 13 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DTJ
LONG TERM....DTJ
AVIATION...RABERDING
AREA FORECAST DISCUSSION...UPDATED
NWS PUEBLO CO
1130 PM MST SAT DEC 15 2012
.UPDATE...
UPDATED TO EXTEND THE WINTER WEATHER ADVISORY FOR THE EASTERN SAN
JUAN RANGE UNTIL 4 AM. THE LATEST WRF RUN AND SATELLITE ANALYSIS
INDICATES THE UPPER LEVEL STORM SYSTEM IS MOVING A BIT SLOWER THAN
EARLY MODEL SOLUTIONS. MODERATE SNOWFALL WILL CONTINUE ACROSS THE
EASTERN SAN JUANS THROUGH MUCH OF TONIGHT AS THE UPPER SYSTEM
BEGINS TO MOVE OUT OF THE AREA. AN ADDITIONAL 1 TO 3 INCHES
WITH LOCALLY HIGHER AMOUNTS ON WEST FACING SLOPES ARE POSSIBLE
OVER THE EASTERN SAN JUANS THROUGH EARLY SUNDAY MORNING. ELSEWHERE
LIGHT SNOW WILL CONTINUE OVER THE MOUNTAIN AREAS WITH A COUPLE OF
INCHES POSSIBLE OVER THE SOUTHERN SANGRE DE CRISTO RANGE. MOZLEY
&&
.PREV DISCUSSION... /ISSUED 1003 PM MST SAT DEC 15 2012/
AVIATION...
KALS...LIGHT SNOW IS CURRENTLY MOVING ACROSS THE SAN LUIS VALLEY
AND IMPACTING KALS. IT HAS REDUCED CIGS TO NEAR 1500 FEET AND VIS
TO AROUND 1SM. EXPECT PERIODS OF LIGHT SNOW TO PERSIST THROUGH
AROUND 10Z WITH VFR CONDITIONS DEVELOPING AFTER 10Z.
KCOS AND KPUB...MID AND UPPER LEVEL CLOUDS WILL SPREAD ACROSS THE
REGION TONIGHT INTO SUNDAY MORNING BUT EXPECT CONDITIONS TO REMAIN
VFR THROUGH THE NEXT 24 HOURS. 88
PREV DISCUSSION... /ISSUED 254 PM MST SAT DEC 15 2012/
SHORT TERM...
(TONIGHT AND SUNDAY)
.ROUNDS OF SNOW TO CONTINUE ALONG THE CONTINENTAL DIVIDE...
NEXT UPPER TROF ALREADY MOVING THROUGH UT TOWARDS THE 4 CORNERS
REGION AND WILL BE MOVING ACROSS SRN CO TONIGHT. STARTING TO SEE
SOME ENHANCEMENT AHEAD OF THIS FEATURE ACROSS SW UT...AND SUSPECT
THAT SNOW WILL BE PICKING UP AGAIN ACROSS THE WOLF CREEK PASS AREA
BY LATE AFTERNOON. ITS BEEN SNOWING MAJORITY OF THE DAY ALONG THE
CONTDVD...BUT BASED ON WEB CAMS AT WOLF CREEK SKI AREA AND CDOT WEB
CAMS...IT DOESN`T APPEAR AS HEAVY AS YESTERDAY. LATEST NAM12 HAS
COME IN A BIT HEAVIER WITH SNOWFALL AMOUNTS DURING THE EVENING WHEN
BRUNT OF FORCING AND DEEPER MOISTURE MOVES IN. WILL ALSO HAVE SOME
INSTABILITY TO PLAY WITH. ALL IN ALL...STILL LOOKS LIKE A SOLID
ADVISORY EVENT FOR THE EASTERN SAN JUANS WITH SNOWFALL TOTALS
RANGING FROM 5 TO 10 INCHES WITH LOCALLY UP TO A FOOT FOR THE
PEAKS. HAVE OPTED TO EXTEND THE WINTER WEATHER ADVISORY FOR ZONE 68
THROUGH 07Z...AS LATEST RUNS APPEAR A LITTLE SLOWER WITH THE
SYSTEM.
FOR THE REMAINDER OF THE REGION...HAVE ALREADY HAD ONE WAVE OF
UPGLIDE LIFT OFF TO THE NORTHEAST OF THE AREA. THIS BROUGHT SOME
ISOLATED LIGHT SHOWERS TO THE PIKES PEAK REGION RIGHT AROUND THE
NOON HOUR. AS THE NEXT WAVE APPROACHES...EXPECT ANOTHER ROUND TO
SPREAD IN DURING THE EVENING HOURS. DON`T THINK IT WILL AMOUNT TO
MUCH EAST OF THE MTS...BUT SOME AREAS ALONG MONUMENT HILL COULD PICK
UP SOME LIGHT ACCUMS RANGING FROM A TRACE TO AN INCH.
INTERESTINGLY...THE 18Z NAM HAS BACKED OFF ON SNOWFALL FOR THIS
REGION...HOWEVER RUC13 HANDLED THE EARLIER WAVE OF LIGHT SNOW
BETTER...SO WILL LEAN TOWARDS ITS SOLN AND MAINTAIN ISOLATED POPS
(SCATTERED ACROSS TELLER COUNTY/NRN EL PASO) THROUGH THE EVENING.
RUC HAS THE NEXT WAVE OF PRECIP MOVING INTO THIS AREA AROUND 01Z.
SHOULD ALSO SEE ANOTHER ROUND OF SNOW SPREAD ACROSS THE SAN LUIS
VALLEY AND INTO THE SANGRE DE CRISTO MOUNTAINS BETWEEN 03Z AND 09Z.
HAVE INCREASED POPS ACROSS THESE AREAS TO ACCOUNT FOR THIS.
ADDITIONAL ACCUMULATIONS OF 1 TO 4 INCHES WILL BE POSSIBLE FOR THE
HIGHER PEAKS. MOST OF THE SAN LUIS VALLEY SHOULD SEE LESS THAN AN
INCH...BUT SOME AREAS COULD SEE SLIGHTLY MORE...ESPECIALLY AGAINST
THE WEST SLOPES OF THE SANGRES...NEAR CRESTONE.
SYSTEM WILL EXIT EASTERN COLORADO BY EARLY SUNDAY MORNING. LIGHT
SNOW CONTINUES ALONG THE CONTINENTAL DIVIDE THROUGH THE DAY...BUT AM
ONLY GETTING ANOTHER INCH OR TWO OF ACCUMS...WHICH IS NOT ENOUGH TO
WARRANT ANY FURTHER HEADLINES AT THIS POINT. OTHERWISE...WEST TO
NORTHWEST WINDS BEHIND THE DEPARTING SYSTEM SHOULD HELP BOOST TEMPS
TO NEAR CLIMATOLOGICAL NORMALS. HAVE GONE ON THE COLDER SIDE OF
GUIDANCE FOR THE SAN LUIS VALLEY DUE TO SNOW COVER. -KT
LONG TERM...
(SUNDAY NIGHT THROUGH NEXT SATURDAY)
LONGER TERM METEOROLOGICAL CHALLENGES INCLUDE POPS...TEMPERATURES
AND GUSTY WINDS AT TIMES. RELATIVELY MOIST NORTHWESTERLY TO ZONAL
UPPER FLOW OVER THE FORECAST DISTRICT FROM SUNDAY NIGHT INTO
TUESDAY WILL ALLOW SNOW TO BE NOTED AT TIMES OVER THE SAN JUAN AND
ESPECIALLY THE CENTRAL MOUNTAINS.
AT THIS TIME...HAVE DEPICTED PERSISTENT RELATIVELY LIGHT SNOW OVER
THE CENTRAL MOUNTAINS FROM SUNDAY NIGHT INTO TUESDAY WITH INDIVIDUAL
6 HOUR SNOW AMOUNTS RARELY OVER 2 INCHES. ELSEWHERE...PROJECT THAT
BASICALLY DRY CONDITIONS WILL BE THE RULE FROM SUNDAY NIGHT INTO
TUESDAY.
FROM TUESDAY NIGHT INTO WEDNESDAY EVENING...A STRONGER UPPER WAVE
MOVES ACROSS THE FORECAST DISTRICT. THIS SYSTEM IS EXPECTED TO
ENHANCE PRECIPITATION CHANCES...GENERATE GUSTY WINDS AND PRODUCE
COOLER TEMPERATURES DURING THIS PERIOD. HAVE ADJUSTED LATEST GRIDS
AND ZONES TO REFLECT THIS TREND.
DRY UPPER RIDGING THEN BUILDING OVER SOUTHERN COLORADO FROM LATER
WEDNESDAY NIGHT INTO FRIDAY WILL ALLOW WARMER AND DRIER CONDITIONS
TO RETURN TO THE FORECAST DISTRICT WITH GRADUALLY INCREASINGLY
MOIST SOUTHWESTERLY UPPER FLOW THEN IMPINGING ON THE CWFAS WESTERN
MOUNTAINS BY NEXT SATURDAY.
WARMEST CONDITIONS OF THE LONGER TERM ARE IN STORE MONDAY AND
TUESDAY AND THEN AGAIN FRIDAY...WHILE COOLEST TEMPERATURES ARE
ANTICIPATED FROM WEDNESDAY INTO WEDNESDAY NIGHT. FINALLY...THE
STRONGEST WINDS OF THE LONGER TERM SHOULD BE NOTED AT TIMES FROM
LATER MONDAY NIGHT INTO THURSDAY...ESPECIALLY OVER EASTERN
PORTIONS OF THE FORECAST DISTRICT.
AVIATION...
ANOTHER ROUND OF HEAVIER SNOW SHOULD MOVE INTO THE SOUTHWEST AND
CENTRAL MOUNTAINS THIS EVENING. MTN OBSCURATIONS WILL CONTINUE WITH
IFR/LIFR VIS AND CIGS IN SHSN. GENERALLY VFR CONDITIONS EXPECTED AT
KCOS AND KPUB THROUGH THE NEXT 24 HOURS...THOUGH -SHSN WILL BE
POSSIBLE AT KCOS DURING THE EVENING AS THE NEXT SYSTEM APPROACHES.
CIGS WITH -SHSN COULD DROP INTO THE MVFR CATEGORY BRIEFLY...THOUGH
ANY ACCUMS SHOULD REMAIN UNDER AN INCH AND MOST LIKELY TO OCCUR TO
THE NORTH OF THE KCOS TERMINAL. KALS COULD ALSO SEE SOME MVFR TO
BRIEF IFR CIGS WITH -SHSN AFTER 01-02Z...WITH ADDITIONAL LIGHT SNOWFALL
ACCUMULATIONS OF UP TO AN INCH POSSIBLE. VFR CONDITIONS WILL
RETURN TO ALL TAF SITES BY EARLY SUNDAY MORNING AS THE SYSTEM PASSES
TO THE EAST OF THE REGION. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 4 AM MST SUNDAY FOR COZ068.
&&
$$
88/10
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1003 PM MST SAT DEC 15 2012
.AVIATION...
KALS...LIGHT SNOW IS CURRENTLY MOVING ACROSS THE SAN LUIS VALLEY
AND IMPACTING KALS. IT HAS REDUCED CIGS TO NEAR 1500 FEET AND VIS
TO AROUND 1SM. EXPECT PERIODS OF LIGHT SNOW TO PERSIST THROUGH
AROUND 10Z WITH VFR CONDITIONS DEVELOPING AFTER 10Z.
KCOS AND KPUB...MID AND UPPER LEVEL CLOUDS WILL SPREAD ACROSS THE
REGION TONIGHT INTO SUNDAY MORNING BUT EXPECT CONDITIONS TO REMAIN
VFR THROUGH THE NEXT 24 HOURS. MOZLEY
&&
.PREV DISCUSSION... /ISSUED 254 PM MST SAT DEC 15 2012/
SHORT TERM...
(TONIGHT AND SUNDAY)
..ROUNDS OF SNOW TO CONTINUE ALONG THE CONTINENTAL DIVIDE...
NEXT UPPER TROF ALREADY MOVING THROUGH UT TOWARDS THE 4 CORNERS
REGION AND WILL BE MOVING ACROSS SRN CO TONIGHT. STARTING TO SEE
SOME ENHANCEMENT AHEAD OF THIS FEATURE ACROSS SW UT...AND SUSPECT
THAT SNOW WILL BE PICKING UP AGAIN ACROSS THE WOLF CREEK PASS AREA
BY LATE AFTERNOON. ITS BEEN SNOWING MAJORITY OF THE DAY ALONG THE
CONTDVD...BUT BASED ON WEB CAMS AT WOLF CREEK SKI AREA AND CDOT WEB
CAMS...IT DOESN`T APPEAR AS HEAVY AS YESTERDAY. LATEST NAM12 HAS
COME IN A BIT HEAVIER WITH SNOWFALL AMOUNTS DURING THE EVENING WHEN
BRUNT OF FORCING AND DEEPER MOISTURE MOVES IN. WILL ALSO HAVE SOME
INSTABILITY TO PLAY WITH. ALL IN ALL...STILL LOOKS LIKE A SOLID
ADVISORY EVENT FOR THE EASTERN SAN JUANS WITH SNOWFALL TOTALS
RANGING FROM 5 TO 10 INCHES WITH LOCALLY UP TO A FOOT FOR THE
PEAKS. HAVE OPTED TO EXTEND THE WINTER WEATHER ADVISORY FOR ZONE 68
THROUGH 07Z...AS LATEST RUNS APPEAR A LITTLE SLOWER WITH THE
SYSTEM.
FOR THE REMAINDER OF THE REGION...HAVE ALREADY HAD ONE WAVE OF
UPGLIDE LIFT OFF TO THE NORTHEAST OF THE AREA. THIS BROUGHT SOME
ISOLATED LIGHT SHOWERS TO THE PIKES PEAK REGION RIGHT AROUND THE
NOON HOUR. AS THE NEXT WAVE APPROACHES...EXPECT ANOTHER ROUND TO
SPREAD IN DURING THE EVENING HOURS. DON`T THINK IT WILL AMOUNT TO
MUCH EAST OF THE MTS...BUT SOME AREAS ALONG MONUMENT HILL COULD PICK
UP SOME LIGHT ACCUMS RANGING FROM A TRACE TO AN INCH.
INTERESTINGLY...THE 18Z NAM HAS BACKED OFF ON SNOWFALL FOR THIS
REGION...HOWEVER RUC13 HANDLED THE EARLIER WAVE OF LIGHT SNOW
BETTER...SO WILL LEAN TOWARDS ITS SOLN AND MAINTAIN ISOLATED POPS
(SCATTERED ACROSS TELLER COUNTY/NRN EL PASO) THROUGH THE EVENING.
RUC HAS THE NEXT WAVE OF PRECIP MOVING INTO THIS AREA AROUND 01Z.
SHOULD ALSO SEE ANOTHER ROUND OF SNOW SPREAD ACROSS THE SAN LUIS
VALLEY AND INTO THE SANGRE DE CRISTO MOUNTAINS BETWEEN 03Z AND 09Z.
HAVE INCREASED POPS ACROSS THESE AREAS TO ACCOUNT FOR THIS.
ADDITIONAL ACCUMULATIONS OF 1 TO 4 INCHES WILL BE POSSIBLE FOR THE
HIGHER PEAKS. MOST OF THE SAN LUIS VALLEY SHOULD SEE LESS THAN AN
INCH...BUT SOME AREAS COULD SEE SLIGHTLY MORE...ESPECIALLY AGAINST
THE WEST SLOPES OF THE SANGRES...NEAR CRESTONE.
SYSTEM WILL EXIT EASTERN COLORADO BY EARLY SUNDAY MORNING. LIGHT
SNOW CONTINUES ALONG THE CONTINENTAL DIVIDE THROUGH THE DAY...BUT AM
ONLY GETTING ANOTHER INCH OR TWO OF ACCUMS...WHICH IS NOT ENOUGH TO
WARRANT ANY FURTHER HEADLINES AT THIS POINT. OTHERWISE...WEST TO
NORTHWEST WINDS BEHIND THE DEPARTING SYSTEM SHOULD HELP BOOST TEMPS
TO NEAR CLIMATOLOGICAL NORMALS. HAVE GONE ON THE COLDER SIDE OF
GUIDANCE FOR THE SAN LUIS VALLEY DUE TO SNOW COVER. -KT
LONG TERM...
(SUNDAY NIGHT THROUGH NEXT SATURDAY)
LONGER TERM METEOROLOGICAL CHALLENGES INCLUDE POPS...TEMPERATURES
AND GUSTY WINDS AT TIMES. RELATIVELY MOIST NORTHWESTERLY TO ZONAL
UPPER FLOW OVER THE FORECAST DISTRICT FROM SUNDAY NIGHT INTO
TUESDAY WILL ALLOW SNOW TO BE NOTED AT TIMES OVER THE SAN JUAN AND
ESPECIALLY THE CENTRAL MOUNTAINS.
AT THIS TIME...HAVE DEPICTED PERSISTENT RELATIVELY LIGHT SNOW OVER
THE CENTRAL MOUNTAINS FROM SUNDAY NIGHT INTO TUESDAY WITH INDIVIDUAL
6 HOUR SNOW AMOUNTS RARELY OVER 2 INCHES. ELSEWHERE...PROJECT THAT
BASICALLY DRY CONDITIONS WILL BE THE RULE FROM SUNDAY NIGHT INTO
TUESDAY.
FROM TUESDAY NIGHT INTO WEDNESDAY EVENING...A STRONGER UPPER WAVE
MOVES ACROSS THE FORECAST DISTRICT. THIS SYSTEM IS EXPECTED TO
ENHANCE PRECIPITATION CHANCES...GENERATE GUSTY WINDS AND PRODUCE
COOLER TEMPERATURES DURING THIS PERIOD. HAVE ADJUSTED LATEST GRIDS
AND ZONES TO REFLECT THIS TREND.
DRY UPPER RIDGING THEN BUILDING OVER SOUTHERN COLORADO FROM LATER
WEDNESDAY NIGHT INTO FRIDAY WILL ALLOW WARMER AND DRIER CONDITIONS
TO RETURN TO THE FORECAST DISTRICT WITH GRADUALLY INCREASINGLY
MOIST SOUTHWESTERLY UPPER FLOW THEN IMPINGING ON THE CWFAS WESTERN
MOUNTAINS BY NEXT SATURDAY.
WARMEST CONDITIONS OF THE LONGER TERM ARE IN STORE MONDAY AND
TUESDAY AND THEN AGAIN FRIDAY...WHILE COOLEST TEMPERATURES ARE
ANTICIPATED FROM WEDNESDAY INTO WEDNESDAY NIGHT. FINALLY...THE
STRONGEST WINDS OF THE LONGER TERM SHOULD BE NOTED AT TIMES FROM
LATER MONDAY NIGHT INTO THURSDAY...ESPECIALLY OVER EASTERN
PORTIONS OF THE FORECAST DISTRICT.
AVIATION...
ANOTHER ROUND OF HEAVIER SNOW SHOULD MOVE INTO THE SOUTHWEST AND
CENTRAL MOUNTAINS THIS EVENING. MTN OBSCURATIONS WILL CONTINUE WITH
IFR/LIFR VIS AND CIGS IN SHSN. GENERALLY VFR CONDITIONS EXPECTED AT
KCOS AND KPUB THROUGH THE NEXT 24 HOURS...THOUGH -SHSN WILL BE
POSSIBLE AT KCOS DURING THE EVENING AS THE NEXT SYSTEM APPROACHES.
CIGS WITH -SHSN COULD DROP INTO THE MVFR CATEGORY BRIEFLY...THOUGH
ANY ACCUMS SHOULD REMAIN UNDER AN INCH AND MOST LIKELY TO OCCUR TO
THE NORTH OF THE KCOS TERMINAL. KALS COULD ALSO SEE SOME MVFR TO
BRIEF IFR CIGS WITH -SHSN AFTER 01-02Z...WITH ADDITIONAL LIGHT SNOWFALL
ACCUMULATIONS OF UP TO AN INCH POSSIBLE. VFR CONDITIONS WILL
RETURN TO ALL TAF SITES BY EARLY SUNDAY MORNING AS THE SYSTEM PASSES
TO THE EAST OF THE REGION. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST TONIGHT FOR COZ068.
&&
$$
88/10
AREA FORECAST DISCUSSION
NWS MIAMI FL
1233 AM EST SUN DEC 16 2012
.AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST WITH
A LIGHT EAST SURFACE WIND. LAND BREEZE COULD SET UP ALONG EAST
COAST WITH THE MORE INLAND TERMINALS BECOMING LIGHT WEST LESS THAN
5 KNOTS BETWEEN 06-12Z BEFORE BECOMING EAST 8-10 KNOTS. A SEA
BREEZE MAY ALSO TRY AND SET UP ALONG THE SOUTHWEST COAST BUT AT
THIS TIME HAVE LEFT OUT OF THE FORECAST FOR NOW AS IT WILL BE VERY
BRIEF LATE THIS AFTERNOON.
KOB
&&
.PREV DISCUSSION... /ISSUED 858 PM EST SAT DEC 15 2012/
UPDATE...
ALTHOUGH LATEST MIAMI SOUNDING SHOWS SLIGHTLY DRIER AIR IN THE
LOWER LEVELS, STUBBORN PATCH OF CLOUDS/SHOWERS STILL AFFECTING
PARTS OF SOUTH FLORIDA, ESPECIALLY ACROSS NORTHERN MIAMI-DADE
COUNTY. RAISED POPS FOR THE FIRST HALF OF THE NIGHT TO 20/30
PERCENT SOUTH OF ALLIGATOR ALLEY TO ACCOUNT FOR CURRENT TRENDS,
WITH LOWER POPS OVERNIGHT AS BACK EDGE OF MOISTURE SHOULD START TO
MOVE IN. ADDITIONAL CLOUDS WITH LIKELY A FEW SHOWERS DOWNWIND OVER
THE NORTHERN BAHAMAS MAY HOLD TOGETHER ENOUGH TO KEEP AN ISOLATED
SHOWER MENTION EAST COAST ALL NIGHT, BUT FOR NOW WILL REMAIN
OPTIMISTIC AND KEEP OUT OF ZONE FORECAST.
ALSO KEPT PATCHY FOG FOR INLAND AREAS OVERNIGHT AS HIGH SURFACE
MOISTURE WITH DEWPOINTS IN LOWER/MID 60S AND LIGHTER WINDS
SHOULD PROMOTE FOG DEVELOPMENT. ALL OTHER FORECAST ELEMENTS LOOK
GOOD. /MOLLEDA
PREV DISCUSSION... /ISSUED 630 PM EST SAT DEC 15 2012/
AVIATION...
MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THE END OF THE TAF
PERIOD. SHOWERS ARE BEGINNING TO REDEVELOP OVER THE ATLANTIC
WATERS AND MOVING IN THE GENERAL DIRECTION OF KOPF AND KMIA. SO
WILL KEEP VCSH IN FOR THOSE TAF SITES FOR THE NEXT SEVERAL HOURS.
MVFR CONDITIONS WILL BE POSSIBLE IF A SHOWER GOES OVER ONE OF THE
TAF SITES. LIGHT EAST NORTHEAST OR EAST WINDS ARE EXPECTED
OVERNIGHT. WINDS WILL VEER TO THE SOUTHEAST DURING THE DAY ON
SUNDAY AND INCREASE TO AROUND 10 KNOTS. THERE WILL STILL BE A
CHANCE FOR LIGHT SHOWERS NEAR THE SOUTHERN HALF OF THE EAST COAST
TAF SITES ON SUNDAY...BUT LEFT OUT OF THE TAF SITES FOR NOW.
PREV DISCUSSION... /ISSUED 238 PM EST SAT DEC 15 2012/
DISCUSSION...
SCATTERED SHOWERS CONTINUE TO STREAM INTO SOUTH FLORIDA UNDER A
CONTINUED MID LEVEL INVERSION AND EAST-NORTHEASTERLY SURFACE FLOW.
LATEST HRRR DEPICTS SHOWERS DIMINISHING IN COVERAGE THROUGH THE
EVENING AND OVERNIGHT HOURS AS UPPER RIDGING BEGINS TO BUILD
ACROSS THE AREA FROM THE GULF OF MEXICO. AS RIDGING BUILDS
IN...WINDS WILL BEGIN TO DIMINISH ACROSS THE ATLANTIC WATERS
REDUCING THE RIP CURRENT THREAT SLIGHTLY INTO SUNDAY. WITH LIGHTER
WINDS OVERNIGHT AND CONTINUED LOW LEVEL MOISTURE...PLACED PATCHY
FOG ACROSS INTERIOR AREAS THROUGH THE OVERNIGHT AND EARLY MORNING
HOURS.
SUNDAY INTO MONDAY LOOK MAINLY DRY AS UPPER RIDGING DOMINATES THE
SOUTH FLORIDA PENINSULA. SURFACE WINDS WILL BECOME MORE
SOUTHEASTERLY AS A COLD FRONT APPROACHES FROM THE NORTH. BY MONDAY
NIGHT RIDGING WILL BEGIN TO BREAK DOWN AS THE FRONT PUSHES INTO
CENTRAL FLORIDA. SHOWERS AND POSSIBLE THUNDERSTORMS ARE EXPECTED
TO DEVELOP AND PUSH ACROSS SOUTH FLORIDA AS THE FRONT PASSES
THROUGH TUESDAY AFTERNOON. MODELS SEEM TO HAVE A GOOD HANDLE ON
THE TIMING OF THIS SYSTEM.
BY WEDNESDAY RIDGING RETURNS IN THE WAKE OF THE FRONT. WEDNESDAY
MORNING COULD SEE LOWS IN THE 40S ACROSS INTERIOR AREAS WITH MID
TO UPPER 50S ELSEWHERE. THE OVERALL PATTERN FOR THE LATTER HALF OF
NEXT WEEK SEEMS TO BE MUCH MORE PROGRESSIVE. SOUTHERLY FLOW
QUICKLY RETURNS OVERNIGHT WEDNESDAY INTO THURSDAY AS ANOTHER FRONT
APPROACHES THE NORTHERN GULF OF MEXICO. RAIN CHANCES RETURN FRIDAY
AS THE FRONT PUSHES INTO SOUTH FLORIDA.
MARINE...
EAST-NORTHEASTERLY WINDS ARE SLOWLY BECOMING MORE EASTERLY AND ARE
BEGINNING TO WEAKEN SLIGHTLY ACROSS THE ATLANTIC WATERS. SHOULD
STILL SEE SEAS IN THE 5 TO 6 FOOT RANGE ACROSS MAINLY THE NEAR AND
OFFSHORE WATERS OF PALM BEACH COUNTY. DECIDED TO KEEP MENTION OF
SMALL CRAFT SHOULD EXERCISE CAUTION FOR THIS AREA. ALSO EXTENDED THE
HIGH RISK OF RIP CURRENTS ACROSS THE BEACHES OF PALM BEACH COUNTY.
FIRE WEATHER...
STILL NO FIRE WEATHER CONCERNS AT THIS TIME. LOW LEVEL MOISTURE
WILL REMAIN WELL ABOVE CRITICAL THRESHOLDS ACROSS THE ENTIRE AREA
THROUGH THE PERIOD.
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS TOPEKA KS
346 AM CST SUN DEC 16 2012
.DISCUSSION...
09Z WATER VAPOR IMAGERY SHOWS A COMPACT SHORTWAVE OVER THE NM/CO
ROCKIES. A SECOND SHORTWAVE WAS NOTED OVER THE PACIFIC NORTHWEST. AT
THE SURFACE...WEAK RIDGING WAS SEEN FROM THE NORTHERN PLAINS INTO
NORTHERN KS.
FOR TODAY THROUGH MONDAY...A RATHER DISORGANIZED CYCLONIC FLOW IS
PROGGED TO AFFECT THE AREA WITH THE SHORTWAVES NOTED ON WATER VAPOR
TRAVERSING THE AREA. INITIALLY FORECAST SOUNDINGS FROM THE RAP AND
NAM SHOW SOME MID LEVEL DRY AIR THAT HAS TO BE OVERCOME WITH THE
BETTER MID LEVEL SATURATION REMAINING JUST NORTH OF THE STATE LINE.
WITH THIS IN MIND AND THE MODELS SHOWING THE SHORTWAVE OVER NM/CO
WEAKENING AS IT MOVES EAST...WILL MAINTAIN THE MENTION OF FLURRIES
AND OR SPRINKLES ACROSS THE FAR NORTHERN COUNTIES THINKING THAT ANY
PRECIP WILL NOT BE MEASURABLE. IT SEEMS THAT DRY LOW LEVELS FOR
TONIGHT AND MONDAY MORNING WILL ALSO LIMIT PRECIP CHANCES AS THE
WAVE OVER THE PACIFIC NORTHWEST KICKS THE LONGWAVE TROUGH EAST. WITH
WEAK COLD AIR ADVECTION AND INCREASING CLOUDS...TEMPS SHOULD BE
COOLER TODAY WITH HIGHS GENERALLY IN THE 40S. LOW LEVEL WINDS ARE
EXPECTED TO TURN BACK FROM THE SOUTH AND SOUTHWEST FOR MONDAY...SO
TEMPS SHOULD BEGIN TO MODERATE.
THE NEXT CHANCE FOR MEASURABLE PRECIP CONTINUES TO LOOK LIKE IT WILL
OCCUR WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT...AND WE MAY END UP
SEEING THE FIRST SNOWFALL OF THE WINTER. THE GFS AND ECMWF APPEAR TO
BE CONVERGING ON A PROGRESSIVE SYSTEM MOVING ACROSS THE PLAINS AS
THE NEXT SHORTWAVE TROUGH PROPAGATES ACROSS NORTH AMERICA. WHILE THE
GFS IS NOTABLY FASTER WITH THE SURFACE LOW...THE TRACKS OF THE
SYSTEM ARE SIMILAR FROM BOTH MODEL SOLUTIONS. ALSO BECAUSE OF THE
PROGRESSIVE NATURE OF THE SYSTEM AND BOTH MODELS DEEPENING THE
SURFACE LOW AS IT PASSES SOUTHEAST OF THE FORECAST AREA...THE COLD
AIR IS QUICKER TO PUSH SOUTH DURING THE AFTERNOON WEDNESDAY WITH
TEMPS POTENTIALLY FALLING DURING THE AFTERNOON. THERE APPEARS TO BE
DECENT QG VECTOR CONVERGENCE WITH THE SYSTEM AND MODELS SHOW GOOD
MID LEVEL FRONTOGENESIS NORTHWEST OF THE SURFACE LOW TRACK. GIVEN
THE TEMP PROFILES RAPIDLY COOLING AND THE MESOSCALE FORCING...THINK
THERE COULD BE A BAND OF SNOW FORM LATE WEDNESDAY AFTERNOON AND
THROUGH THE NIGHT. CROSS SECTIONS FROM THE GFS AND ECMWF SUGGEST THE
STRONGER VERTICAL MOTION WILL OCCUR BETWEEN 00 AND 06Z THUR WITH DRY
AIR AND SUBSIDENCE QUICKLY FILLING IN TOWARDS 12Z. BECAUSE OF THE
PROGRESSIVE NATURE OF THE SYSTEM...SNOW AMOUNTS LOOK TO BE ON THE
ORDER OF A COUPLE INCHES.
SOMEWHAT ZONAL FLOW DEVELOPS IN THE WAKE OF THE WEDNESDAY NIGHT
SYSTEM...WITH THE UPPER LEVEL JET SETTING UP ACROSS THE SOUTHERN
HALF OF THE COUNTRY. THIS SHOULD KEEP A DRY AND COOL AIRMASS OVER
THE PLAINS FOR THURSDAY NIGHT THROUGH SATURDAY.
WOLTERS
&&
.AVIATION...
MOSTLY CLEAR SKIES ACROSS THE TERMINALS HAS LED TO MVFR/IFR FOG TO
DEVELOP OVER THE PAST HOUR EXCEPT IN KTOP. WITH LIGHT WINDS...EXPECT
MORE IFR/VLIFR FOG TO DEVELOP NEXT 1-3 HOURS. HOWEVER...AFT 08-09Z
SOME MID AND HIGH CLOUDS MAY BE OFFSETTING FACTOR ALONG WITH DRY AIR
JUST ABOVE THE FOG...SO HAVE INCREASED VSBYS AFT THAT TIME THROUGH
ON THRU 14Z. BEYOND 14Z HAVE CONTINUED VFR CONDITIONS WITH LIGHT
NORTH/NORTHEAST WINDS AND MID LEVEL AC DECK AROUND 12 KFT.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
342 AM CST SUN DEC 16 2012
...UPDATED SYNOPSIS AND SHORT TERM DISCUSSION...
.SYNOPSIS...
ISSUED AT 341 AM CST SUN DEC 16 2012
THE 00Z UPPER AIR ANALYSIS SHOWED A SOMEWHAT SPLIT FLOW PATTERN
OVER WESTERN NORTH AMERICA. IN THE NORTH, SHORTWAVE TROUGHS WERE
MOVING OVER THE CENTRAL CANADIAN PRAIRIE AND INTO BRITISH COLUMBIA.
FARTHER SOUTH, THE SHORTWAVE TROUGH THAT MOVED OUT OF THE CENTRAL
HIGH PLAINS SUNDAY MORNING WAS OVER THE GREAT LAKES REGION. FARTHER
WEST, A COMPACT SHORTWAVE WAS MOVING ACROSS SOUTHERN COLORADO WHILE
ANOTHER WAVE WAS ON ITS HEELS OVER THE GREAT BASIN INTO ARIZONA.
THE REGIONAL RADAR MOSAIC SHOWS A SMALL AREA OF LIGHT TO MODERATE
SNOW OVER FAR SOUTHWEST NEBRASKA, WHICH APPEARS TO BE FORCED BY
SOME MID LEVEL FRONTOGENESIS. RADAR RETURNS OVER SOUTHERN COLORADO
HAVE BEEN FAIRLY LIGHT SO FAR THIS MORNING.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 341 AM CST SUN DEC 16 2012
THE COLORADO SHORTWAVE HAS BEEN PROGRESSING STEADILY EASTWARD PER
SATELLITE LOOPS. EXTRAPOLATING IT AT ITS CURRENT SPEED WOULD PUT IT
OVER SOUTH CENTRAL KANSAS BY 18Z. THE 00Z NAM HAS A PRETTY GOOD
HANDLE ON THIS. THIS MODEL ALSO KEEPS ANY PRECIPITATION ASSOCIATED
WITH THIS WAVE OVER FAR NORTHERN KANSAS THIS MORNING. THE LATEST
RUNS OF THE RUC13 ARE ALSO DRY BUT IT DOES TRY TO DEVELOP SOME
LIGHT PRECIPITATION OVER SOUTH CENTRAL KANSAS TOWARD MIDDAY. BASED
ON CURRENT RADAR TRENDS, HAVE OPTED TO LOWER POPS ACROSS WEST
CENTRAL KANSAS THIS MORNING AND REMOVE THE MENTION OF SPRINKLES
FROM THE FORECAST. THIS WILL HAVE TO BE WATCHED FOR THE NEXT FEW
HOURS FOR ANY CHANGES IN THE CURRENT RADAR TRENDS.
ONCE THE FIRST WAVE MOVES OUT OF WESTERN KANSAS, WE SHOULD SEE AN
INCREASE IN SUNSHINE FOR A WHILE UNTIL CIRRUS ASSOCIATED WITH THE
NEXT WAVE BEGINS TO MOVE IN FROM THE WEST. THIS COULD HELP BOOST
TEMPERATURES UP A LITTLE THIS AFTERNOON AND HAVE ADJUSTED TODAY`S
HIGH TEMPERATURES UP A BIT ESPECIALLY OVER CENTRAL KANSAS.
THE NEXT WAVE WILL MOVE OUT OVER THE CENTRAL HIGH PLAINS THIS
EVENING AND SHOULD BE EAST OF THE AREA BY MIDNIGHT. AM NOT
EXPECTING ANY SIGNIFICANT PRECIPITATION WITH THIS WAVE AS WELL.
HAVE LOWERED SUNDAY NIGHTS LOW TEMPERATURES A FEW DEGREES CLOSER
TO THE NAM MOS NUMBERS.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 318 PM CST SAT DEC 15 2012
TRANQUIL WEATHER IS ANTICIPATED SUNDAY NIGHT THROUGH TUESDAY NIGHT
MID TO UPPER LEVEL RIDGING BUILDS ACROSS THE ROCKIES AND PLAINS AND
HIGH PRESSURE POSITIONS ITSELF ACROSS THE SOUTHERN ROCKIES. THE
ATMOSPHERIC COLUMN WILL BE FAIRLY DRY BRINGING PARTLY CLOUDY SKIES
AND DRY CONDITIONS TO SOUTHWEST KANSAS. WINDS WILL GENERALLY BE FROM
THE WEST MONDAY INTO TUESDAY THEN SHIFTING MORE OF A SOUTHERLY
DIRECTION TUESDAY NIGHT. LOWS MONDAY MORNING WILL BE IN THE 20S
WITH HIGHS MONDAY AFTERNOON REACHING TO THE LOWER 50S. LOWS TUESDAY
MORNING ARE FORECASTED TO RANGE FROM THE UPPER 20S TO AROUND 30
DEGREES WITH HIGHS TUESDAY AFTERNOON IN THE MID TO UPPER 50S. LOWS
BY SUNRISE WEDNESDAY ARE FORECASTED TO BE IN THE LOWER 30S.
THE NEXT STORM SYSTEM STARTS TO AFFECT WESTERN KANSAS ON WEDNESDAY
AS AN UPPER LEVEL SHORTWAVE AND STRONG UPPER LEVEL JET MOVES INTO
THE CENTRAL ROCKIES. MID LEVEL MOISTURE ADVECTS INTO THE AREA AS THE
DAY PROGRESSES BRINGING AN INCREASE IN CLOUDINESS. MEDIUM RANGE
MODELS DIFFER SLIGHTLY ON THE SPEED OF THIS SYSTEM WITH THE GFS
BEING THE FASTEST AND THE ECMWF SLIGHTLY SLOWER. NEVERTHELESS, THE
MODELS DEPICT A STATIONARY FRONT MOVING INTO WEST CENTRAL KANSAS
WEDNESDAY AFTERNOON WITH AN INCREASE IN PRECIPITATION CHANCES ACROSS
THE SAME AREA WEDNESDAY EVENING. PRECIPITATION CHANCES THEN SPREAD
ACROSS THE REMAINDER OF SOUTHWEST KANSAS WEDNESDAY NIGHT WITH A COLD
FRONT MOVING THROUGH WESTERN KANSAS. WINDS SHIFT TO THE NORTH BEHIND
THIS FRONT. IT IS TOO FAR OUT TO PIN POINT PRECIPITATION TYPE BUT
FIRST GUESS HAS PRECIPITATION STARTING OUT AS RAIN WEDNESDAY EVENING
CHANGING OVER TO ALL SNOW AFTER MIDNIGHT. THIS SYSTEM THEN MOVES OUT
OF THE AREA BY THURSDAY MORNING WITH DECREASING CLOUDINESS FROM WEST
TO EAST. WITH CLOUDINESS AND COOLER TEMPERATURES BEHIND THE FRONT,
WEDNESDAY`S HIGHS ARE FORECASTED TO RANGE FROM THE LOWER 40S ACROSS
WEST CENTRAL KANSAS TO UPPER 50S ACROSS THE KS/OK BORDER. LOWS
THURSDAY MORNING ARE FORECASTED TO DIP INTO THE 20S.
ZONAL WEST TO EAST ZONAL FLOW DEVELOPS THURSDAY INTO THE WEEKEND
WITH HIGH PRESSURE BEING THE DOMINATE FEATURE ACROSS THE SOUTHERN
PLAINS AT THE SURFACE. THIS WILL SUPPRESS ANY ACTIVITY ACROSS
WESTERN KANSAS BRINGING MOSTLY CLEAR SKIES AND DRY CONDITIONS. HIGHS
ARE FORECASTED TO BE IN THE UPPER 30S AND LOWER 40S THURSDAY THEN IN
THE 40S FRIDAY. LOWS FRIDAY AND SATURDAY MORNING WILL GENERALLY BE
IN THE LOWER TO MID 20S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1209 AM CST SUN DEC 16 2012
AN UPPER LEVEL DISTURBANCE WILL MOVE OUT OF SOUTHERN COLORADO ACROSS
SOUTHERN KANSAS LATE TONIGHT THROUGH SUNDAY MORNING. THIS WILL BRING
SCATTERED TO OCCASIONALLY BROKEN MID TO HIGH LEVEL CLOUDS, ALONG
WITH POSSIBLE SPRINKLES, ACROSS WESTERN KANSAS THROUGH THE FIRST
PART OF THE PERIOD. THERE IS A VERY SMALL CHANCE FOR A BRIEF PERIOD
OF IFR CIGS AT GARDEN CITY AND DODGE CITY BETWEEN 12Z AND 15Z BUT
CONFIDENCE IS TOO LOW TO ADD IT TO THE TAFS AT THIS TIME.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 47 24 54 29 / 10 10 0 0
GCK 47 22 52 28 / 10 10 0 0
EHA 49 25 54 31 / 10 0 0 0
LBL 50 22 54 29 / 10 10 0 0
HYS 42 24 52 28 / 10 10 0 0
P28 51 29 57 30 / 10 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...GERARD
SHORT TERM...GERARD
LONG TERM...HOVORKA_42
AVIATION...GERARD
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
143 AM EST SUN DEC 16 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE FROM PLAINS STATES INTO THE GREAT LAKES
REGION TONIGHT THROUGH SUNDAY...PUSHING A WARM FRONT THROUGH THE
AREA. ANOTHER AREA OF LOW PRESSURE MOVES FROM THE OHIO VALLEY TO
THE NORTHEASTERN STATES MONDAY...WITH THE TRAILING COLD FRONT
CROSSING THE REGION EARLY TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
LONGWAVE IR IMAGERY SHOWS COOLING CLOUD TOPS INDICATIVE OF AN
EMBEDDED IMPULSE OVER EASTERN TN. THIS WAVE IS EXPECTED TO
INTERACT WITH INCREASING WAA AS A WARM FRONT LIFTS N ACROSS THE
CAROLINA COASTAL PLAIN. THE LATEST RUC PROGS RATHER STRONG LOW/MID
LEVEL LIFT LATE TONIGHT INTO EARLY SUNDAY MORNING ACROSS SE VA AND
NE NC. POPS HAVE BEEN INCREASED TO LIKELY INTO SUNDAY
MORNING...GIVEN THE SATELLITE TRENDS AND LATEST RUC SOLUTIONS. AT
THIS POINT ANTECEDENT DRY CONDITIONS ARE STILL EXPECTED DELAY THE
ONSET OF ANY RAIN...BUT KRAX AND KAKQ RADARS ARE INDICATING AN
INCREASE IN LOW-LEVEL MOISTURE BY SHOWING LIGHT ECHOES FROM
CENTRAL NC TO THE TIDEWATER. GENERALLY QPF AMOUNTS SHOULD
GENERALLY RANGE BETWEEN 0.1-0.2IN ACROSS EXTREME SE VA AND COASTAL
NE NC...BUT THERE IS SOME INDICATION OF POTENTIAL ELEVATED
CONVECTIVE ELEMENTS THAT COULD RESULT IN UP TO 0.2-0.3IN.
OTHERWISE...ONLY SLIGHT CHANCE/CHANCE POPS ARE FORECAST ELSEWHERE.
OVERNIGHT MINIMA ARE LIKELY OCCURRING THIS EVENING...ESPECIALLY
ACROSS THE SE WHERE LOWS FROM THE MID 30S TO LOW 40S WILL RISE TO
THE UPPER 40S TO LOW 50S BY MORNING. ELSEWHERE...TEMPERATURES
SHOULD BE STEADY IN THE LOW TO MID 40S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
WARM FRONT LIFTS NORTH ACROSS THE REGION SUNDAY MORNING, WITH A BIT
OF A LULL IN ACCUMULATING PCPN EXPECTED SUN MORN. SHORTWAVE TROUGH
IS PROGGED TO FOLLOW SW FLOW ALOFT, PUSHING ACROSS THE REGION LATER
SUNDAY. THUS, RAIN CHANCES INCREASE AGAIN BY LATE SUNDAY MORNING
INTO EARLY EVENING. CONTINUE TO ORIENT HIGHEST (LIKELY) RAIN CHANCES
ACROSS ROUGHLY ALONG AND NORTH OF I-64, WITH LOWER CHCS FOR RAIN, OR
A FEW SHRAS OVER SE VA AND NE NC. TEMPERATURES FAIRLY MILD AS FA
REMAINS IN WARM SECTOR AHEAD OF APPROACHING COLD FRONT. HIGHS A BIT
OF A CHALLENGE GIVEN CONTINUED SIGNIFICANT CLOUD COVER. LOOKING FOR
M-U50S NORTH TO L-M60S SOUTH.
FIRST SLUG OF MOISTURE/SHORTWAVE KICKS OFF THE DELMARVA COAST SUNDAY
NIGHT. MIDLVL DRY OUT A BIT, WHICH WOULD TEND TO FAVOR SOME PATCHY
DZ/FOG RATHER THAN ACCUMULATING PCPN LATE SUN NIGHT/ERY MONDAY
MORNING. GIVEN ONSHORE FLOW/WAA AND CONSIDERABLE CLOUDINESS, WENT
AOA WARMER MET GUIDANCE. LOWS ~50-55.
MONDAY...
BRIEF LULL IN PCPN MONDAY MORNING AHEAD OF SECOND SHORTWAVE, WHICH
IS EXPECTED TO BEGIN TO CROSS THE LOCAL AREA MIDDAY MONDAY INTO MON
NIGHT. HAVE AGAIN ORIENTED BEST POPS IN THE AFTN/EVE TIME FRAME
MONDAY. DESPITE INCREASINGLY MOIST AIRMASS, QPF VALUES APPEAR RATHER
MEAGER WITH BETTER FORCING ONCE AGAIN OFF TO OUR NORTH (FROM THE OH
VLY INTO THE NORTHEAST) AND TO OUR SOUTH. STILL, QPF OF AN
ADDITIONAL ONE TO TWO-TENTHS ON AVERAGE APPEARS REASONABLE. DESPITE
SHRAS AND CONSIDERABLE CLOUDS, RATHER MILD W/ CONTINUED WAA. LOOK
FOR HIGHS INTO THE U50S-NR 60 ACROSS THE PIEDMONT, L-M60S ELSEWHERE.
MONDAY NIGHT/TUESDAY...
SECOND SHORTWAVE PIVOTS NE/OFFSHORE LATE MON. UPPER LOW
DAMPENS/WEAKENS A BIT AS IT MOVES FROM THE MIDDLE MS VALLEY MON
NIGHT NE TO THE EASTERN GREAT LAKES BY TUESDAY MORNING...PUSHING
THE ATTENDANT SFC FRONT EAST AS WELL. NUMERICAL GUIDANCE HAS
SLOWED SLIGHTLY WITH FRONTAL TIMING. NEW 12Z SUITE OF DATA LOOKS
TO BRING FRONT THROUGH BY/SHORTLY AFTER DAWN TUESDAY MORNING.
GIVEN WEAK FRONTAL FORCING, EXPECT THIS TIMING TO CONTINUE TO SLOW
SLIGHTLY WITH SUBSEQUENT RUNS. THUS, GIVEN THIS SLOWER TIMING AND
WITH SIG CAA LIKELY TO LAG BEHIND FROPA, HV KEPT MAXIMA IN THE
U50S/NR 60 WEST, M-U60S SE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
TRENDED EXTENDED PERIOD FORECAST TOWARD THE LATEST EUROPEAN MODEL,
AS A STORM SYSTEM BRINGS WET CONDITIONS AND COOL TEMPS TO THE MID
ATLANTIC STATES TOWARD THE END OF NEXT WEEK.
UPPER/SFC LOW WILL CONTINUE TO PUSH OFFSHORE WED MORNING AS COOL
MID/UPPER LEVEL TROUGH LOCATES OVER THE INTERMOUNTAIN WEST.
UPPER/SFC HIGH PRESSURE WILL BUILD INTO THE REGION WEDS AS DEEP WLY
FLOW BRINGS SUNNY TO PARTLY SUNNY SKIES. AS THE BEST COLD AIR WILL
REMAIN NORTH OF THE REGION...850 TEMPS ONLY EXPECTED TO FALL TO
RIGHT AROUND FREEZING. THUS...HAVE TRENDED TEMPS WEDS A FEW DEGS
WARMER INTO THE MID/UPPER 50S.
SFC HIGH PRESSURE WILL DRIFT OFF THE SE COAST THURSDAY MORNING AS
THE MID LEVEL RIDGE AXIS MOVES EAST OF THE REGION LATE THURSDAY
MORNING. DEPARTING LOW PRESSURE FROM EARLIER IN THE WEEK WILL PHASE
WITH STRONG LOW OVER THE NORTHERN ATLANTIC...HELPING AMPLIFY THE
EAST COAST RIDGE. THIS WILL RESULT IN INCREASED SWLY FLOW AND
MOISTURE ADVECTION INTO THE REGION. CLOUDS WILL ALSO BE ON THE
INCREASE WITH MOSTLY CLOUDY/CLOUDY SKIES EXPECTED BY THURSDAY
AFTERNOON. WHILE HEIGHTS/THICKNESS VALUES INCREASE...CLOUD COVER AND
WEAK MIXING WILL LIMIT AFTERNOON WARMING WITH TEMPS ONLY EXPECTED IN
THE LOW/MID 50S N TO MID/UPPER 50S S.
WHILE SPATIAL AND TIMING DIFFERENCES EXIST WITH THE COLD FRONT IN
EACH RUN...FRONT IS EXPECTED TO REACH THE FA THURS NIGHT AND CROSS
THE REGION THROUGH FRIDAY MORNING. BEST FORCING FOR ASCENT LOOKS TO
BE OVER THE REGION AS VORT MAX AND PV ANOMALY...AS WELL AS COUPLING
SUBTROPICAL/POLAR JET INCREASE DIVERGENCE ALOFT. COULD SEE A GOOD
CHANCE AT WIDESPREAD BENEFICIAL RAIN SHOWERS. COLD POLAR CONTINENTAL
AIR WILL RUSH IN BEHIND THE SYSTEM WITH TEMPS EXPECTED IN THE MID
40S NE TO MID 50S SW FRIDAY AFTERNOON (TEMPS MAY FALL DURING THE DAY
DEPENDING ON FRONTAL TIMING). TEMPS WILL FALL INTO THE MID/UPPER 20S
SATURDAY MORNING ONLY TO REBOUND INTO THE LOW/MID 40S SATURDAY
AFTERNOON...POSSIBLY COLDER. MOST OF THE PRECIP WILL BE TIED TO THE
FRONT AND BEATING THE POLAR AIR...TEMPS WILL BE WARM ENOUGH TO
SQUASH ANY WINTRY MIX FRIDAY MORNING.
AS OMEGA BLOCKING IS FORECAST TO OCCUR OVER THE NORTHERN ATLANTIC
THROUGH NEXT WEEKEND...COLD WEATHER IS LIKELY TO CONTINUE THROUGH
THE WEEKEND AS ANOTHER SHORTWAVE REINFORCES THE COLD AIR.
HOWEVER...DRY CONDITIONS WILL PREVAIL.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
CONTD INCRS IN MOISTURE/LWRG OF CLDNS IN THE NEXT 24-36 HRS. KEPT
CIGS IN MVFR CAT (ALG W/ SCT -RA) INTO TNGT...W/ LO PROB FOR IFR
(CIGS AND/OR VSBY). ADDITIONAL -RA PSBL TNGT/MON W/ A HIGHER PROB
FOR IFR CIGS/VSBYS...ESP AFT MDNGT TNGT/MON MRNG. GRADUAL
IMPROVEMENT MON NGT...THEN VFR CONDS W/ GUSTY WNW WNDS TUE INTO
WED. A CHANCE OF SHOWERS BY LT THU.
&&
.MARINE...
SFC HIGH PRESSURE HAS ALLOWED FOR CALM WINDS AOB 10 KT OVER THE
WATERS THIS AFTERNOON WITH SEAS GENERALLY 2 TO 3 FT. HIGH PRESSURE
WILL SHIFT OFFSHORE THIS EVENING AS A WEAK COASTAL LOW LIFTS UP
THE SE COAST TONIGHT BRINGING LIGHT RAIN AND S/SE WINDS ALONG THE
COAST. LOW PRESSURE WILL THEN LIFT OUT OF THE MIDWEST
MONDAY...WITH A SECONDARY AREA OF LOW PRESSURE DEVELOPING JUST
NORTH OF THE WATERS MONDAY NIGHT/TUESDAY. WINDS WILL BACK TO THE
S/SW MONDAY AFTERNOON (5 TO 10 KT). WITH HIGH PRESSURE LOCATED
OFFSHORE...THE PRESSURE GRADIENT WILL TIGHTEN ALLOWING FOR
INCREASINGLY SLY WINDS OVER THE WATERS BEGINNING MONDAY EVENING. A
WEAK COLD FRONT WILL CROSS THE WATERS MONDAY NIGHT INTO
TUESDAY...BACKING THE WINDS TO THE W/NW AND ALLOWING FOR STRONGER
CAA ALOFT. SEAS WILL BEGIN TO BUILD 4 TO 5 FT TUESDAY
AFTERNOON...THUS SCA HEADLINES WILL LIKELY BE NEEDED AT LEAST OVER
THE NORTHERN COASTAL ZONES. STRONGEST CAA WILL OCCUR TUESDAY NIGHT
INTO WEDNESDAY...WHICH WILL LEAD TO LIKELY SCA CONDITIONS OVER THE
WATERS.
WINDS/SEAS WILL BEGIN TO SUBSIDE WEDS AFTERNOON AS HIGH PRESSURE
BUILDS IN FROM THE SOUTH. ANOTHER STRONGER LOW PRESSURE SYSTEM
WILL IMPACT THE REGION TOWARD THE END OF NEXT WEEK WITH SCA
CONDITIONS LIKELY.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MAM
NEAR TERM...AJZ/MAS/MAM
SHORT TERM...MAM
LONG TERM...MPR/SAM
AVIATION...ALB
MARINE...MAS/SAM
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1204 AM EST SUN DEC 16 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE FROM PLAINS STATES INTO THE GREAT LAKES
REGION TONIGHT THROUGH SUNDAY...PUSHING A WARM FRONT THROUGH THE
AREA. ANOTHER AREA OF LOW PRESSURE MOVES FROM THE OHIO VALLEY TO
THE NORTHEASTERN STATES MONDAY...WITH THE TRAILING COLD FRONT
CROSSING THE REGION EARLY TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
LONGWAVE IR IMAGERY SHOWS COOLING CLOUD TOPS INDICATIVE OF AN
EMBEDDED IMPULSE OVER EASTERN TN. THIS WAVE IS EXPECTED TO
INTERACT WITH INCREASING WAA AS A WARM FRONT LIFTS N ACROSS THE
CAROLINA COASTAL PLAIN. THE LATEST RUC PROGS RATHER STRONG LOW/MID
LEVEL LIFT LATE TONIGHT INTO EARLY SUNDAY MORNING ACROSS SE VA AND
NE NC. POPS HAVE BEEN INCREASED TO LIKELY INTO SUNDAY
MORNING...GIVEN THE SATELLITE TRENDS AND LATEST RUC SOLUTIONS. AT
THIS POINT ANTECEDENT DRY CONDITIONS ARE STILL EXPECTED DELAY THE
ONSET OF ANY RAIN...BUT KRAX AND KAKQ RADARS ARE INDICATING AN
INCREASE IN LOW-LEVEL MOISTURE BY SHOWING LIGHT ECHOES FROM
CENTRAL NC TO THE TIDEWATER. GENERALLY QPF AMOUNTS SHOULD
GENERALLY RANGE BETWEEN 0.1-0.2IN ACROSS EXTREME SE VA AND COASTAL
NE NC...BUT THERE IS SOME INDICATION OF POTENTIAL ELEVATED
CONVECTIVE ELEMENTS THAT COULD RESULT IN UP TO 0.2-0.3IN.
OTHERWISE...ONLY SLIGHT CHANCE/CHANCE POPS ARE FORECAST ELSEWHERE.
OVERNIGHT MINIMA ARE LIKELY OCCURRING THIS EVENING...ESPECIALLY
ACROSS THE SE WHERE LOWS FROM THE MID 30S TO LOW 40S WILL RISE TO
THE UPPER 40S TO LOW 50S BY MORNING. ELSEWHERE...TEMPERATURES
SHOULD BE STEADY IN THE LOW TO MID 40S.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
WARM FRONT LIFTS NORTH ACROSS THE REGION SUNDAY MORNING, WITH A BIT
OF A LULL IN ACCUMULATING PCPN EXPECTED SUN MORN. SHORTWAVE TROUGH
IS PROGGED TO FOLLOW SW FLOW ALOFT, PUSHING ACROSS THE REGION LATER
SUNDAY. THUS, RAIN CHANCES INCREASE AGAIN BY LATE SUNDAY MORNING
INTO EARLY EVENING. CONTINUE TO ORIENT HIGHEST (LIKELY) RAIN CHANCES
ACROSS ROUGHLY ALONG AND NORTH OF I-64, WITH LOWER CHCS FOR RAIN, OR
A FEW SHRAS OVER SE VA AND NE NC. TEMPERATURES FAIRLY MILD AS FA
REMAINS IN WARM SECTOR AHEAD OF APPROACHING COLD FRONT. HIGHS A BIT
OF A CHALLENGE GIVEN CONTINUED SIGNIFICANT CLOUD COVER. LOOKING FOR
M-U50S NORTH TO L-M60S SOUTH.
FIRST SLUG OF MOISTURE/SHORTWAVE KICKS OFF THE DELMARVA COAST SUNDAY
NIGHT. MIDLVL DRY OUT A BIT, WHICH WOULD TEND TO FAVOR SOME PATCHY
DZ/FOG RATHER THAN ACCUMULATING PCPN LATE SUN NIGHT/ERY MONDAY
MORNING. GIVEN ONSHORE FLOW/WAA AND CONSIDERABLE CLOUDINESS, WENT
AOA WARMER MET GUIDANCE. LOWS ~50-55.
MONDAY...
BRIEF LULL IN PCPN MONDAY MORNING AHEAD OF SECOND SHORTWAVE, WHICH
IS EXPECTED TO BEGIN TO CROSS THE LOCAL AREA MIDDAY MONDAY INTO MON
NIGHT. HAVE AGAIN ORIENTED BEST POPS IN THE AFTN/EVE TIME FRAME
MONDAY. DESPITE INCREASINGLY MOIST AIRMASS, QPF VALUES APPEAR RATHER
MEAGER WITH BETTER FORCING ONCE AGAIN OFF TO OUR NORTH (FROM THE OH
VLY INTO THE NORTHEAST) AND TO OUR SOUTH. STILL, QPF OF AN
ADDITIONAL ONE TO TWO-TENTHS ON AVERAGE APPEARS REASONABLE. DESPITE
SHRAS AND CONSIDERABLE CLOUDS, RATHER MILD W/ CONTINUED WAA. LOOK
FOR HIGHS INTO THE U50S-NR 60 ACROSS THE PIEDMONT, L-M60S ELSEWHERE.
MONDAY NIGHT/TUESDAY...
SECOND SHORTWAVE PIVOTS NE/OFFSHORE LATE MON. UPPER LOW
DAMPENS/WEAKENS A BIT AS IT MOVES FROM THE MIDDLE MS VALLEY MON
NIGHT NE TO THE EASTERN GREAT LAKES BY TUESDAY MORNING...PUSHING
THE ATTENDANT SFC FRONT EAST AS WELL. NUMERICAL GUIDANCE HAS
SLOWED SLIGHTLY WITH FRONTAL TIMING. NEW 12Z SUITE OF DATA LOOKS
TO BRING FRONT THROUGH BY/SHORTLY AFTER DAWN TUESDAY MORNING.
GIVEN WEAK FRONTAL FORCING, EXPECT THIS TIMING TO CONTINUE TO SLOW
SLIGHTLY WITH SUBSEQUENT RUNS. THUS, GIVEN THIS SLOWER TIMING AND
WITH SIG CAA LIKELY TO LAG BEHIND FROPA, HV KEPT MAXIMA IN THE
U50S/NR 60 WEST, M-U60S SE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
TRENDED EXTENDED PERIOD FORECAST TOWARD THE LATEST EUROPEAN MODEL,
AS A STORM SYSTEM BRINGS WET CONDITIONS AND COOL TEMPS TO THE MID
ATLANTIC STATES TOWARD THE END OF NEXT WEEK.
UPPER/SFC LOW WILL CONTINUE TO PUSH OFFSHORE WED MORNING AS COOL
MID/UPPER LEVEL TROUGH LOCATES OVER THE INTERMOUNTAIN WEST.
UPPER/SFC HIGH PRESSURE WILL BUILD INTO THE REGION WEDS AS DEEP WLY
FLOW BRINGS SUNNY TO PARTLY SUNNY SKIES. AS THE BEST COLD AIR WILL
REMAIN NORTH OF THE REGION...850 TEMPS ONLY EXPECTED TO FALL TO
RIGHT AROUND FREEZING. THUS...HAVE TRENDED TEMPS WEDS A FEW DEGS
WARMER INTO THE MID/UPPER 50S.
SFC HIGH PRESSURE WILL DRIFT OFF THE SE COAST THURSDAY MORNING AS
THE MID LEVEL RIDGE AXIS MOVES EAST OF THE REGION LATE THURSDAY
MORNING. DEPARTING LOW PRESSURE FROM EARLIER IN THE WEEK WILL PHASE
WITH STRONG LOW OVER THE NORTHERN ATLANTIC...HELPING AMPLIFY THE
EAST COAST RIDGE. THIS WILL RESULT IN INCREASED SWLY FLOW AND
MOISTURE ADVECTION INTO THE REGION. CLOUDS WILL ALSO BE ON THE
INCREASE WITH MOSTLY CLOUDY/CLOUDY SKIES EXPECTED BY THURSDAY
AFTERNOON. WHILE HEIGHTS/THICKNESS VALUES INCREASE...CLOUD COVER AND
WEAK MIXING WILL LIMIT AFTERNOON WARMING WITH TEMPS ONLY EXPECTED IN
THE LOW/MID 50S N TO MID/UPPER 50S S.
WHILE SPATIAL AND TIMING DIFFERENCES EXIST WITH THE COLD FRONT IN
EACH RUN...FRONT IS EXPECTED TO REACH THE FA THURS NIGHT AND CROSS
THE REGION THROUGH FRIDAY MORNING. BEST FORCING FOR ASCENT LOOKS TO
BE OVER THE REGION AS VORT MAX AND PV ANOMALY...AS WELL AS COUPLING
SUBTROPICAL/POLAR JET INCREASE DIVERGENCE ALOFT. COULD SEE A GOOD
CHANCE AT WIDESPREAD BENEFICIAL RAIN SHOWERS. COLD POLAR CONTINENTAL
AIR WILL RUSH IN BEHIND THE SYSTEM WITH TEMPS EXPECTED IN THE MID
40S NE TO MID 50S SW FRIDAY AFTERNOON (TEMPS MAY FALL DURING THE DAY
DEPENDING ON FRONTAL TIMING). TEMPS WILL FALL INTO THE MID/UPPER 20S
SATURDAY MORNING ONLY TO REBOUND INTO THE LOW/MID 40S SATURDAY
AFTERNOON...POSSIBLY COLDER. MOST OF THE PRECIP WILL BE TIED TO THE
FRONT AND BEATING THE POLAR AIR...TEMPS WILL BE WARM ENOUGH TO
SQUASH ANY WINTRY MIX FRIDAY MORNING.
AS OMEGA BLOCKING IS FORECAST TO OCCUR OVER THE NORTHERN ATLANTIC
THROUGH NEXT WEEKEND...COLD WEATHER IS LIKELY TO CONTINUE THROUGH
THE WEEKEND AS ANOTHER SHORTWAVE REINFORCES THE COLD AIR.
HOWEVER...DRY CONDITIONS WILL PREVAIL.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
LOW CONFIDENCE FORECAST FOR SUNDAY AS WARM ADVECTION STRATUS
DEVELOPS OVER THE REGION. USED A MIXTURE OF GUIDANCE WITH NAM
SEEMING TO LOW. EXPECT LOWEST BASES WILL BE OVER NRN AREAS. A FEW
HOURS OF LIGHT RAIN IS EXPECTED THROUGH MID MRNG. KEPT IFR OUT
OF THE FCST AT ORF AND ECG. LOW CLOUDS BASES EXPECTED TO ONLY
IMPROVE A LITTLE DURING THE LATE MRNG AND EARLY AFTN. MOST GUIDANCE
BRINGS IFR BACK TO THE TAF SITES BY LATE AFTN BUT DID NOT INCLUDE IT
THIS FAR OUT.
IN THE SHORT TERM...SINCE PUTTING OUT THE TAF...MVFR VSBYS HAVE
DEVELOPED AT PHF AND ORF AS T/TD SPREAD HAS DECREASED UNDER A THIN
PARTIAL CLOUD COVER. WILL MONITOR BUT DO NOT SEE INDICATION OF
WIDESPREAD IFR AT THIS TIME AS CLOUDS INCREASE ACROSS THE AREA.
OUTLOOK...PERIODS OF IFR ALONG WITH PCPN ARE EXPECTED THROUGH MONDAY
NIGHT. CONDITIONS IMPROVE TUESDAY WITH DRY WEATHER FORECAST THROUGH
WEDNESDAY. A CHANCE FOR SHOWERS RETURNS THURSDAY.
&&
.MARINE...
SFC HIGH PRESSURE HAS ALLOWED FOR CALM WINDS AOB 10 KT OVER THE
WATERS THIS AFTERNOON WITH SEAS GENERALLY 2 TO 3 FT. HIGH PRESSURE
WILL SHIFT OFFSHORE THIS EVENING AS A WEAK COASTAL LOW LIFTS UP
THE SE COAST TONIGHT BRINGING LIGHT RAIN AND S/SE WINDS ALONG THE
COAST. LOW PRESSURE WILL THEN LIFT OUT OF THE MIDWEST
MONDAY...WITH A SECONDARY AREA OF LOW PRESSURE DEVELOPING JUST
NORTH OF THE WATERS MONDAY NIGHT/TUESDAY. WINDS WILL BACK TO THE
S/SW MONDAY AFTERNOON (5 TO 10 KT). WITH HIGH PRESSURE LOCATED
OFFSHORE...THE PRESSURE GRADIENT WILL TIGHTEN ALLOWING FOR
INCREASINGLY SLY WINDS OVER THE WATERS BEGINNING MONDAY EVENING. A
WEAK COLD FRONT WILL CROSS THE WATERS MONDAY NIGHT INTO
TUESDAY...BACKING THE WINDS TO THE W/NW AND ALLOWING FOR STRONGER
CAA ALOFT. SEAS WILL BEGIN TO BUILD 4 TO 5 FT TUESDAY
AFTERNOON...THUS SCA HEADLINES WILL LIKELY BE NEEDED AT LEAST OVER
THE NORTHERN COASTAL ZONES. STRONGEST CAA WILL OCCUR TUESDAY NIGHT
INTO WEDNESDAY...WHICH WILL LEAD TO LIKELY SCA CONDITIONS OVER THE
WATERS.
WINDS/SEAS WILL BEGIN TO SUBSIDE WEDS AFTERNOON AS HIGH PRESSURE
BUILDS IN FROM THE SOUTH. ANOTHER STRONGER LOW PRESSURE SYSTEM
WILL IMPACT THE REGION TOWARD THE END OF NEXT WEEK WITH SCA
CONDITIONS LIKELY.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MAM
NEAR TERM...AJZ/MAS/MAM
SHORT TERM...MAM
LONG TERM...MPR/SAM
AVIATION...LSA
MARINE...MAS/SAM
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1129 PM CST SAT DEC 15 2012
.AVIATION...
A WEAK STORM SYSTEM WILL AFFECT WESTERN NEBRASKA TONIGHT WITH
BKN100 CEILINGS LOWERING THROUGH MVFR CEILINGS OVER SOUTHWEST NEBRASKA.
LIGHT SNOW WILL CONTINUE OVER SOUTHWEST NEBRASKA BETWEEN KOGA AND
KIML. CONFIDENCE NOT HIGH FOR SNOW TOO IMPACT KLBF SO HAVE LEFT
OUT OF THE TAF FOR NOW. CIGS MAY LOWER INTO IFR OVER SOUTHWEST
NEBRASKA SUNDAY MORNING.
&&
.PREV DISCUSSION... /ISSUED 356 PM CST SAT DEC 15 2012/
UPDATE...
DISCUSSION...
JUST A QUICK REFRESH ON THE POPS AND QPF ACROSS SWRN NEB. NO REAL
CHANGE BUT QPF PLUMES SUGGEST HIGHER CONFIDENCE FORM KOGA SOUTH
THROUGH KIML SO POPS ARE UP SLIGHTLY AND MEASUREABLE QPF IS FCST A
BIT FARTHER NORTH.
PREV DISCUSSION... /ISSUED 301 PM CST SAT DEC 15 2012/
DISCUSSION...
THE AREA OF WEAK DEFORMATION ACROSS NERN COLO WILL DRIFT EAST
NORTHEAST AND DECAY THIS EVENING. THUS FAR NO SNOW OR RAIN HAS
REACHED THE GROUND DESPITE THE PERSISTENT RADAR RETURNS. LATER
TONIGHT...A SECOND IMPULSE...CURRENTLY ACROSS THE SRN ROCKIES...WILL
LIFT NORTHEAST FORMING A SECOND AREA OF WEAK DEFORMATION WHICH
COULD DRIFT ACROSS SRN NEB AFTER MIDNIGHT PRODUCING LIGHT SNOW.
THE MODELS ARE HAVING A HARD TIME WITH SOME SOLNS SHOWING
DEFORMATION ACROSS THE SAND HILLS AND OTHERS ACROSS SRN NEB.
THE CONSENSUS OF SOLNS SUPPORTS LIGHT SNOW ACROSS SRN NEB. CHANCE
POPS ARE IN PLACE WITH ACCUMULATIONS LESS THAN AN INCH. HPC
SUGGESTED LITTLE OR NO ACCUMULATION ACROSS SWRN NEB. THE ECM
SHOWED 2 INCHES NEAR KOGA...THE GFS SHOWED 5 INCHES NEAR
KIML...THE GEM SHOWED 2 INCHES NEAR KIML AND THE NAM SHOWED AN
INCH ALL OVER THE PLACE. THE RAP HAS BEEN WOBBLING 1 TO 2 INCHES
NORTH AND SOUTH...GENERALLY NEAR OR SOUTH OF INTERSTATE 80.
IT WOULD BE BEST TO WAIT FOR THE RADAR AND SFC OBSERVATIONS TO
LIGHT UP AND THEN GET MORE SPECIFIC WITH POPS AND SNOW AMOUNTS SINCE
THIS IS A FAIRLY COMPACT AREA OF SNOW THE MODELS ARE FORECASTING
TO DEVELOP. THE MODELS ARE SHOWING A WEAK AREA OF ARCTIC HIGH PRESSURE
BUILDING DOWN TONIGHT AND THE PROGRESS OF THAT AIR COULD HAVE A
LOT TO DO WITH THE LOCATION OF THE SNOWFALL. ALSO...THE NAN AND
RUC SHOW RAIN THIS EVENING AHEAD OF THE FRONT..THEN SNOW WHILE THE
GFS IS ALL SNOW.
THIS SYSTEM WILL EXIT THE FCST AREA LATE IN THE DAY SUNDAY MAKING
FOR A COOL DAY AS THE ARCTIC HIGH DRIFTS EAST...LOW PRESSURE
REFORMS ACROSS THE CNTL HIGH PLAINS AND SOUTH WINDS DEVELOP
RECYCLING COLD AIR NORTH.
THE NEXT WEATHER SYSTEM OF INTEREST CROSSES THE FCST AREA TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT. THERE ARE TWO SCENARIOS SHOWN IN THE
MODELS. THE ECM SUGGESTS A MORE SOUTHERLY ROUTE TAKING A LEAD
SHORT WAVE AND DEFORMATION ZONE THROUGH NORTHWEST NEBRASKA
FOLLOWED BY THE MAIN FORCING THROUGH SRN NEB AND KANSAS...MOSTLY
SOUTH AND EAST OF THE FCST AREA. THE GEM AND GFS SUGGEST A MORE
CLASSIC DISTURBANCE CRIS CROSSING THE COLD FRONT PRODUCING LIGHT
SNOW THROUGHOUT THE FCST AREA. THE FCST USED 50 PERCENT OF THE ECM
AND 25 PERCENT OF THE OTHER TWO MODELS. ALL MODELS SHOW WEAK
FRONTOGENESIS ACROSS NW NEB TUESDAY NIGHT. THE ECM QUICKLY DECAYS
THAT FEATURE WHILE THE GEM AND GFS CARRY THAT ACROSS THE FCST
AREA. EITHER WAY...BY THURSDAY MORNING H10-5 THICKNESSES FALL TO
BELOW 520 DM AND H850 TEMPERATURES ARE AROUND MINUS 7C.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...POWER
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1257 AM EST SUN DEC 16 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE INTO THE GREAT LAKES THROUGH SUNDAY...WITH
A COLD FRONT MOVING INTO THE OHIO VALLEY THROUGH SUNDAY NIGHT. AN
AREA OF LOW PRESSURE WILL THEN DEVELOP ON MONDAY...WITH ANOTHER
COLD FRONT FOLLOWING ON MONDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
GOING FORECAST PRETTY MUCH ON TARGET RIGHT NOW. UPDATED TO STOP
ANY MORE FALL IN TEMPS...THE WARM SECTOR CONTINUES TO SLOWLY
ESTABLISH ITSELF OVER THE FORECAST AREA...AND WITH THE
THICK/EXPANSIVE/LOWERING STRATUS AND INCREASING SWLY BOUNDARY
LAYER FLOW IT WILL BE TOUGH FOR TEMPS TO DROP FROM CURRENT VALUES.
MAINTAINED THE LOW SHOWER CHANCE TONIGHT - BUT THOUGHT HEAVILY
ABOUT PULLING IT COMPLETELY IN LIEU OF LOW RAIN CHANCES JUST FOR
MEASURABLE DRIZZLE. DEEP MOISTURE /PER EVENING SATELLITE LOOPS AND
16.00Z KILN SOUNDING/ IS ABSENT SO HAVE THE FEELING THE
LIGHT/SPECKLED QPF SEEN ON MANY DETERMINISTIC 15.18Z DATASETS IS
PROBABLY REFLECTION OF THE DRIZZLE THAT HAS BEEN SEEN IN HIT/MISS
FASHION TO OUR WEST. THAT SAID...RADAR ECHO OVER CNTL/NRN IND DOES
HAVE SHOWERY LOOK TO IT AT TIMES SO KEPT MENTION OF BOTH DRIZZLE
AND SHOWERS OVERNIGHT BUT THINK AREAS OF DRIZZLE PROBABLY WIN OUT
IN TERMS OF WHAT/S MORE PREVALENT. IN TERMS OF DRIZZLE...THE
16.00Z NAM AND RECENT 16.XXZ RUNS OF RAP INDICATE THE 0-2KM
RH WILL CONTINUE TO EXPAND/INCREASE THROUGH THE NIGHT SO WE SHOULD
SEE AREAS OF -DZ INCREASE ESP AFTER 06Z. WINDS WILL CONTINUE TO
VEER/SLOWLY INCREASE THROUGH THE NIGHT AS WEAK LOW MEANDERS
THROUGH WISCONSIN AND INTO NRN LOWER MICH.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
THE BASIC PREMISE OF THE SHORT TERM FORECAST HAS COME INTO BETTER
AGREEMENT WITH THE 12Z MODEL CYCLE...BUT MANY OF THE DETAILS
REMAIN SOMEWHAT UNCERTAIN.
AS CLOUDS GRADUALLY LIFT ON SUNDAY MORNING...DRIZZLE IS EXPECTED
TO COME TO AN END. A SLOW MOVING AND ILL-DEFINED FRONT WILL BE
MOVING INTO THE REGION FROM THE NORTH...ASSOCIATED WITH THE GREAT
LAKES SURFACE LOW. THE TIMING OF THIS FEATURE HAS SLOWED...AND
ONLY THE HIGH-RESOLUTION OF THE NAM12 SHOWS AN INDICATION OF THE
FRONT ACTIVATING IN ANY SIGNIFICANT WAY. MARGINAL INSTABILITY WILL
BE ABLE TO BUILD AHEAD OF THE FRONT...BUT THE FORCING IS NOT
PARTICULARLY STRONG. A SLIGHT CHANCE OF THUNDER HAS BEEN
MAINTAINED IN THE SOUTH AND SOUTHEASTERN PORTIONS OF THE FORECAST
AREA.
A SURFACE LOW IS EXPECTED TO DEVELOP NEAR THE OHIO/MISSISSIPPI
RIVER CONFLUENCE BY MONDAY MORNING...AHEAD OF AN ENERGETIC TROUGH
MOVING THROUGH THE MIDDLE OF THE COUNTRY. SUBTRACTING THE NAM
SOLUTION...MODELS SEEM TO BE AGREEING ON A CINCINNATI-TO-ERIE
TRACK FOR THIS LOW...WITH INCREASED CONFIDENCE IN MEASURABLE
PRECIPITATION ACROSS THE FORECAST AREA. A SIGNIFICANT UPWARD
ADJUSTMENT WAS MADE TO BRING THE ENTIRE CWA TO LIKELY POPS ON
MONDAY. THERE IS AN INDICATION OF SOME WEAK INSTABILITY
DEVELOPING...BUT THIS MAINLY SEEMS TO FOLLOW BEHIND THE GREATER
CHANCES OF PRECIPITATION. THUNDER WAS NOT INCLUDED IN THE FORECAST.
THE STRENGTH OF THE MID LEVEL WAVE WILL HAVE AN IMPACT ON HOW LONG
THE PRECIPITATION IS ABLE TO PERSIST ON EARLY TUESDAY MORNING.
TEMPERATURES BEHIND THE LOW (AND ASSOCIATED COLD FRONT) WILL COOL
OFF ENOUGH TO SUPPORT SNOW AT THE END OF THE FORECAST PERIOD...BUT
WITH PRECIPITATION EXPECTED TO BE MOVING OUT...LITTLE MORE THAN A
RAIN/SNOW MIX WITH NO ACCUMULATION CAN BE FORECAST AT THIS TIME.
WITH THE BOUNDARY AND LOW IN THE AREA DURING THIS PART OF THE
FORECAST...TEMPERATURE GRADIENTS ARE A BIT SHARPER THAN NORMAL FOR
BOTH MAXES AND MINS. WITH THIS IN MIND...AND THE WAY THAT ANY
SMALL MODEL DIFFERENCES COULD CHANGE THE TEMPERATURE FORECAST BY
SEVERAL DEGREES...A BLENDED APPROACH NEAR THE MEDIAN OF THE MODEL
SPECTRUM WAS USED.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
ALTHOUGH THE OPERATIONAL MODELS ARE LATCHING ON TO THE MAIN SYNOPTIC
FEATURES IN THE EXTENDED PERIOD...THERE CONTINUES TO BE CONSIDERABLE
SPREAD IN TERMS OF STRENGTH...TIMING AND A PLACEMENT OF THESE
FEATURES. AS A RESULT...HAVE LEANED MORE ON THE 15.12Z ECMWF AND
BLENDED IT WITH HPC GUIDANCE. THE 15.12Z ECMWF WAS USED DUE TO THE
FACT THAT IT TENDS TO PERFORM BETTER THAN THE GFS IN THE EXTENDED
AND OFTEN LATCHES ON TO A PATTERN A DAY AHEAD OF THE GFS.
ON TUESDAY...LOW PRESSURE WILL CONTINUE TO PUSH NE OF THE REGION AS
A WEAK SURFACE RIDGE BUILDS INTO THE OHIO VALLEY. ANY LINGERING PCPN
IN THE EAST WILL COME TO AN END BY AFTERNOON...FOLLOWED BY PARTIAL
CLEARING. TEMPERATURES WILL REMAIN MILD WITH HIGHS MAINLY IN THE 40S.
FOR TUESDAY NIGHT INTO WEDNESDAY...WEAK SURFACE RIDGE WILL MOVE EAST
AS A MID LEVEL RIDGE BUILDS ACRS THE OHIO VALLEY REGION IN ADVANCE
OF THE NEXT WEATHER SYSTEM. MID AND HIGH LEVEL CLOUDINESS CAN BE
EXPECTED ALONG WITH CONTINUE MILD TEMPERATURES. HIGHS ON WEDNESDAY
WILL RANGE FROM THE LOWER 40S NORTH TO THE LOWER 50S SOUTH.
FOR THE PERIOD WEDNESDAY NIGHT INTO FRIDAY...MODELS CONTINUE TO SHOW
A PATTERN CHANGE IN THE OFFING WITH THE UPR LVL FLOW BECOMING MORE
AMPLIFIED THROUGH THE PERIOD. A VIGOROUS S/WV WILL PIVOT FROM THE
SRN PLAINS TO THE GREAT LAKES REGION THROUGH THE PERIOD. THIS UPR
LVL SUPPORT WILL PERTURB DEEPENING LOW PRESSURE WHICH WILL PUSH A
STRONG COLD FRONT THROUGH THE REGION SOMETIME THURSDAY INTO THURSDAY
NIGHT. IT APPEARS THE SFC LOW WILL TRACK NW OF THE REGION WHICH
WOULD KEEP HEAVIER WINTER PCPN TO THE NW OF THE TRACK AND OUT OF OUR
AREA. DEEP MOISTURE RETURN AND DYNAMICS WILL SPREAD SHOWERS ALONG
AND AHEAD OF A COLD FRONT WEDNESDAY NIGHT INTO THURSDAY. COLDER AIR
IS FORECAST TO SPILL INTO THE REGION THURSDAY NIGHT INTO FRIDAY IN
THE WAKE OF THE LOW/COLD FRONT. THIS WILL CHANGE ANY LIQUID PCPN TO
SNOW SHOWERS WHILE TEMPERATURES DROP. HAVE LIMITED SNOW SHOWERS TO
THE CHANCE CATEGORY THURSDAY NIGHT INTO FRIDAY DUE TO WRAP AROUND
MOISTURE AND COLDER AIR MOVING ACROSS THE WARMER WATER OF THE GREAT
LAKES. ANY SNOW ACCUMULATION SHOULD BE MINOR BUT WILL DEPEND ON THE
EXACT TRACK AND CLOSING OF MID LVL S/WV INTO A MID LEVEL
CIRCULATION. AGAIN...WAY TOO EARLY TO KNOW AT THIS POINT GIVEN THE
MODEL SPREAD MENTIONED. TEMPERATURES WILL DROP TO BELOW NORMAL
READINGS ON FRIDAY IN THE CAA PATTERN.
FOR FRIDAY NIGHT INTO SATURDAY...MODELS ARE IN DISAGREEMENT ON HOW
FAST UPR LVL LOW WILL PULL NE AND WHETHER IT WILL ROTATE BACK TOWARD
THE SOUTHWEST INTO EARLY NEXT WEEK. HAVE GONE WITH PARTLY CLOUDY
SKIES AT THIS POINT WITH A SMALL CHANCE OF SNOW SHOWERS DOWN WIND OF
THE GREAT LAKES...MAINLY ACROSS OUR NRN AND ERN LOCATIONS.
TEMPERATURES ARE EXPECTED TO BE BELOW NORMAL.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
MVFR CIGS HAVE WORKED INTO KCVG AND KLUK. THERE IS SOME
UNCERTAINTY WITH HOW LOW CIGS WILL GET ACROSS THE TAF SITES
OVERNIGHT AND INTO THE EARLY DAYTIME HOURS ON SUNDAY. GENERALLY
EXPECT LOWER CIGS ACROSS THE WESTERN TAF SITES WITH IFR CIGS
POSSIBLE. CIGS ACROSS THE EAST AT KCMH AND KLCK SHOULD REMAIN
HIGHER AND ONLY DROP DOWN INTO THE MVFR CATEGORY.
THERE ARE SOME LIGHT RETURNS ON RADAR HOWEVER NOT MUCH IS SHOWING
UP IN THE WAY OF PRECIPITATION YET WITH THE OBS. AS THE NIGHT
PROGRESSES EXPECT THERE TO BE SOME DRIZZLE ACROSS THE TAF SITES
AND THIS WILL HELP TO REDUCE VSBYS TO THE MVFR CATEGORY. CIGS AND
VSBYS WILL GRADUALLY IMPROVE THROUGH THE DAY ON SUNDAY WITH ANY
PRECIPITATION COMING TO AN END ACROSS THE AREA.
SUNDAY NIGHT A LOW PRESSURE SYSTEM BEGINS TO NEAR THE AREA FROM
THE SOUTH AND CIGS WILL START TO LOWER AGAIN AT THE SOUTHERN TAF
SITES. BEGAN TO BRING IN SOME SHOWER ACTIVITY TO THE AREA AT KCVG
AND KLUK BY THE END OF THE TAF PERIOD.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES POSSIBLE SUNDAY NIGHT
INTO TUESDAY AND THEN AGAIN ON THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...BINAU
SHORT TERM...HATZOS
LONG TERM...HICKMAN
AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1124 PM CST SAT DEC 15 2012
.UPDATE...FOR 06Z AVIATION FORECAST
&&
.AVIATION...
SHOWERS AND ISOLATED THUNDERSTORMS ARE HEADING INTO SOUTHWEST
MIDDLE TENENSSEE AT THIS TIME. EXPECT THIS TREND TO CONTINUE IN
THE OVERNGIHT WITH SHOWERS MORE CONCENTRATED OVER SOUTHERN AND
EASTERN AREAS OF THE MID STATE. ALSO...LOOK FOR CEILINGS AND VSBYS TO
LOWER IN THE OVERNIGHT. ALTHOUGH SOME SCATTERED SHOWERS ARE
EXPECTED OVER THE NORTHWEST THEY WILL BE FEWER IN NUMBER.
BOYD
&&
.PREV DISCUSSION... /ISSUED 834 PM CST SAT DEC 15 2012/
UPDATE...
FORECAST FOR TONIGHT APPEARS ON TRACK AND ONLY MINOR TWEAKS WERE
MADE. WAA CONTINUES TO INCREASE OVER THE MID STATE WITH DEWPOINTS
NOW IN THE MID 40S TO MID 50S. TEMPERATURES HAVE ALSO BEGUN RISING
OVER THE WESTERN HALF AND RAISED LOW TEMPS OVER THAT REGION.
HOWEVER...HAD TO LOWER MINS ON THE PLATEAU WHERE TEMPS ARE
ALREADY NEAR/BELOW FORECAST LOWS...BUT TEMPS SHOULD REMAIN STEADY
OR SLOWLY RISE THERE THE REMAINDER OF THE NIGHT AS WELL.
CURRENT RADAR IMAGERY INDICATES AN AREA OF RAIN WITH A COUPLE OF
THUNDERSTORMS OVER THE PLATEAU. ADDITIONAL ACTIVITY IS FORMING
OVER THE LOWER MISSISSIPPI VALLEY...AND SHORT TERM GUIDANCE
INDICATES THIS WILL SPREAD ACROSS THE MID STATE OVERNIGHT.
ANTICIPATING SOME STRONGER CONVECTION AFTER MIDNIGHT PER 00Z NAM
AND 23Z HRRR RUNS...AND CANNOT RULE OUT AN ISOLATED STRONG OR
MARGINALLY SEVERE STORM OVER SOUTHERN AND EASTERN ZONES. WITH
ACTIVITY ELEVATED ABOVE THE SURFACE INVERSION PER 00Z OHX
SOUNDING...MAIN THREATS WOULD BE GUSTY WINDS OR HAIL DUE TO THE
INTENSE LOW LEVEL SHEAR.
PREV DISCUSSION... /ISSUED 745 PM CST SAT DEC 15 2012/
UPDATE...FOR AVIATION FORECAST
AVIATION...
ELEVATED SHOWER ACTIVITY IS ON-GOING OVER EASTERN AND SOUTHERN SECTIONS
OF THE MID STATE WITH AN OCCASIONAL LIGHTNING STRIKE IN SOME OF THE
STRONGER RETURNS. THIS ACTIVITY REMAINS ELEVATED AND WILL CONTINUE
TO MOVE QUICKLY TOWARD THE NORTHEAST AS WIND FIELDS WILL REMAIN
STRONG ABOVE SURFACE. THERE IS NEWLY DEVELOPED ACTIVITY OVER
NORTHWEST MISSISSIPPI AT 01Z THIS EVENING THAT WILL BE MOVING THIS
WAY ALONG WITH ACTIVITY THAT HAS FIRED FARTHER TO THE SOUTHWEST
OVER NORTHERN LOUISIANA DURING THE PAST HOUR. SREF KEEPS THE BULK
OF THIS ACTIVITY OVER THE SOUTHEAST HALF OF MIDDLE TENNESSEE...GENERALLY
SOUTH AND EAST OF NASHVILLE THROUGH 12Z SUNDAY. AFTER 12Z SUNDAY
ACTIVITY WILL BECOME MORE NUMEROUS ACROSS MIDDLE TENNESSEE EXCEPT
FOR FAR NORTHWEST WHERE IT WILL BE SCATTERED. MARGINALLY SEVERE
STORM OR TWO POSSIBLE ON SUNDAY...ESPECIALLY NEAR ALABAMA BORDER.
WILL UPDATE AVIATION FORECAST AND TWEAK TIMING FOR CONVECTION.
BOYD
PREV DISCUSSION... /ISSUED 617 PM CST SAT DEC 15 2012/
UPDATE...FOR 00Z AVIATION FORECAST
AVIATION...
STILL A RATHER TIGHT SURFACE PRESSURE GRADIENT ACROSS THE TENNESSEE
VALLEY WITH SURFACE GEOSTROPHIC WINDS ON THE ORDER OF 45 TO 50 KNOTS
AT THE TOP OF THE BOUNDARY LAYER. LOW LEVEL JET CURRENTLY PUNCHING
ACROSS EASTERN ARKANSAS AND UP THROUGH WESTERN TENNESSEE AND
KENTUCKY WITH A 160 KNOT UPPER LEVEL JET FROM OKLAHOMA EASTWARD
THROUGH THE OHIO/TENNESSEE VALLEYS. TOTAL TOTALS THIS EVENING ARE
HIGHER TO OUR SOUTH ACROSS NORTHERN ALABAMA/MISSISSIPPI. BUFKIT
SOUNDINGS OFF GFS SHOWING GOOD INVERSION OFF SURFACE DURING MUCH
OF THE OVERNIGHT HOURS SO ANY CONVECTION SHOULD REMAIN ELEVATED
AND ZIP ALONG AT A PRETTY GOOD SPEED OFF TOWARD THE NORTHEAST.
BASICALLY KEPT WHAT THE DAYSHIFT HAD AS FAR AS AVIATION FORECASTS
BUT WILL TAKE CLOSER WHEN NEWER GUIDANCE ARRIVES AND UPDATE
PACKAGE IF NEED BE DURING THE EVENING.
BOYD
PREV DISCUSSION... /ISSUED 254 PM CST SAT DEC 15 2012/
DISCUSSION...
SURFACE ENERGY TO CONTINUE TO PULL NORTH THROUGH THIS AFTERNOON AND
TONIGHT. HOWEVER...SOUTHWESTERLY FLOW ALOFT TO BECOME MORE ACTIVE AS
A SERIES OF IMPULSES RIDES NORTHEAST WITHIN THE FLOW. MOISTURE LEVELS
TO REMAIN WITH SOME ENHANCEMENT EXPECTED OVERNIGHT AND INTO SUNDAY.
A RELATIVELY WEAK FRONTAL BOUNDARY WILL HEAD OUR WAY WITH THE FROPA
EXPECTED ON MONDAY.
PRESSURE GRADIENTS TO REMAIN ON THE TIGHT SIDE THROUGH MONDAY. 10-20
MPH WINDS WITH SOME HIGHER GUSTS TO LIKELY PREVAIL.
OVERALL FOR THE SHORT TERM...RAINFALL CHANCES WILL BE GREATEST
TONIGHT AND SUNDAY WITH THE ACTIVE SOUTHWESTERLY UPPER FLOW. THE
TRAJECTORY AND IMPACT OF THE IMPULSES WILL BE GREATEST ACROSS
SOUTHERN MIDDLE TN AND THE PLATEAU. FOR SUNDAY NIGHT AND
MONDAY...MOISTURE LEVELS WILL DROP BUT THE APPROACHING WEAK FRONTAL
BOUNDARY WILL PROVIDE GENERALLY LOW RAINFALL CHANCES.
IN TERMS OF TSTM POTENTIAL...SHOWALTERS ARE NEAR ZERO WITH LIMITED
SFC CAPE VALUES. WILL STILL INCLUDE ISOL/SCT TSTMS FOR EACH PERIOD.
FOR THE NEAR TERM TEMPS...WARM PATTERN WITH THE MOIST SOUTHERN
DIRECTIONALLY UNIFORM FLOW. SLIGHTLY COOLER FOR MONDAY NIGHT BEHIND
THE FROPA BUT STILL ABOVE NORMAL. REPLACING AIRMASS WILL FEATURE A
SFC HIGH THAT WILL BUILD SLIGHTLY NORTHWARD FROM THE GULF. SO MILD
CONDITIONS TO CONTINUE BEHIND THE FROPA.
IN THE EXTENDED FCST...TUESDAY AND WEDNESDAY WILL FEATURE MOSTLY
SUNNY AND MILD CONDITIONS. THEN... A STRONG COLD FRONT WILL GAIN
STRENGTH AND PUSH ACROSS THE AREA ON THURSDAY. SHOWERS AND TSTMS
LOOK LIKE A GOOD BET FOR THURSDAY AS THE EURO AND GFS SOLUTIONS
MATCH UP QUITE WELL. LOOKS LIKE UP TO AN INCH OF RAINFALL POSSIBLE.
INSTABILITIES ARE JUST STRONG ENOUGH TO WARRANT ISOL TSTMS AS WELL.
COLDER CONDITIONS TO RETURN BEHIND THE FRONT. VERSUS THE MEX...WILL
UNDERCUT RATHER AGGRESSIVELY FOR FRIDAY AND SATURDAY.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1049 PM CST SAT DEC 15 2012
.DISCUSSION...
/SEE BELOW FOR AVIATION DISCUSSION/
&&
.AVIATION...
VFR NEXT 24 HOURS. DRY WESTERLY WINDS PICK UP LATE MORNING AS A
SURFACE TROUGH MOVES EAST THROUGH OKLAHOMA. A FEW GUSTS OF 23-25
KTS POSSIBLE AT KSJT AND KABI...WITH LIGHTER WINDS FARTHER SOUTH.
&&
.PREV DISCUSSION... /ISSUED 512 PM CST SAT DEC 15 2012/
DISCUSSION...
/SEE BELOW FOR AVIATION DISCUSSION/
AVIATION...
VFR NEXT 24 HOURS. MID AND UPPER LEVEL HIGH CLOUDINESS ASSOCIATED
WITH THE SUBTROPICAL JET WILL PERSIST OVERNIGHT AND INTO SUNDAY
MORNING. GUSTY WINDS OF 25-28 KTS TOWARD NOON AT KSJT AND KABI AS
A SURFACE LOW MOVES EAST ACROSS THE TEXAS AND OKLAHOMA PANHANDLES.
04
PREV DISCUSSION... /ISSUED 306 PM CST SAT DEC 15 2012/
SHORT TERM...
TEMPERATURES THIS AFTERNOON RANGE FROM THE LOWER 60S ACROSS THE
NORTHERN BIG COUNTRY TO THE MID 70S ACROSS THE NORTHWEST HILL
COUNTRY. THE GUSTY WEST WINDS THAT WERE FORECAST FOR TODAY NEVER
REALLY MATERIALIZED DUE...IN LARGER PART...TO THE THICK MID/HIGH
CLOUD COVER THAT MOVED IN FROM THE SOUTH AND WEST. THIS IS IN
RESPONSE TO A 150 KT H25 SUBTROPICAL JET STREAK ORIENTED FROM
NORTHWEST MEXICO INTO SOUTHWEST OK. THIS JET AXIS IS PROGGED TO
SLIDE JUST TO OUR SOUTHEAST OVER THE NEXT 24 HOURS WHICH WOULD HELP
ELIMINATE MUCH OF THE HIGH CLOUDS OVER OUR CWA. IN THE MEANTIME...
WE CAN EXPECT MOSTLY CLOUDY SKIES OVERNIGHT WHICH GENERALLY MEANS
WARMER TEMPS THAN THOSE SUGGESTED BY GUIDANCE. I INCREASED MINS
ACROSS THE I-10 CORRIDOR WHERE THE THICKEST CLOUD COVER IS EXPECTED.
OTHERWISE...GUIDANCE LOOKED GOOD WITH LOW 40S. THE RAP WAS
GENERATING LIGHT QPF TONIGHT BUT IT REMAINS AN OUTLIER AND LOOKS
SUSPICIOUS AT BEST.
I EXPECT AT LEAST PARTIAL CLEARING SUNDAY AFTERNOON. THIS SHOULD
ALLOW SOME OF THE STRONGER WINDS ALOFT TO MIX DOWN TO THE SURFACE
AND PROVIDE A FEW HOURS OF GUSTY WEST WINDS. I STILL THINK WIND
SPEEDS WILL REMAIN IN THE 15-20 MPH RANGE ACROSS THE BIG COUNTRY AND
CONCHO VALLEY /LIGHTER ELSEWHERE/ DESPITE TODAY/S HUMBLING EXAMPLE.
THE ENHANCED DOWNSLOPE SHOULD HELP PUSH TEMPS BACK INTO THE UPPER
60S TO LOWER 70S AS H85 TEMPS ARE ONLY PROGGED TO COOL BY AROUND 1C
BY 00Z MONDAY.
JOHNSON
LONG TERM...
THE EXTENDED FORECAST IS CHARACTERIZED BY GENERALLY ABOVE NORMAL
TEMPERATURES AND LITTLE TO NO CHANCE OF PRECIPITATION. AN UPPER
LEVEL TROUGH WILL MOVE ACROSS THE PLAINS ON MONDAY...WITH THE ONLY
REAL AFFECT ON WEST CENTRAL TEXAS BEING AN INCREASE IN WINDS. EXPECT
WEST NORTHWEST WINDS OF 15 TO 20 MPH...WITH TEMPERATURES RANGING
FROM THE MID 60S TO LOWER 70S. A STEADY WARM UP IS FORECAST ON
TUESDAY AND WEDNESDAY AHEAD OF THE NEXT UPPER LEVEL TROUGH. HIGH
TEMPERATURES WILL BE RUNNING 15 TO 20 DEGREES ABOVE SEASONAL
NORMALS...GENERALLY IN THE LOWER TO MID 70S. THE MAIN WEATHER
CONCERN WILL BE THE POTENTIAL FOR STRONG WINDS ON WEDNESDAY. A
FAIRLY POTENT UPPER LEVEL TROUGH WILL APPROACH THE AREA ON
WEDNESDAY...WITH A 994MB SURFACE LOW DEVELOPING OVER THE TEXAS
PANHANDLE. A TIGHT SURFACE PRESSURE GRADIENT WILL DEVELOP ACROSS THE
REGION...RESULTING IN WEST WINDS OF 20 TO 30 MPH...WITH HIGHER
GUSTS...ACROSS MUCH OF THE BIG COUNTRY AND CONCHO VALLEY. FARTHER
SOUTH WINDS SHOULD REMAIN IN THE 15 TO 25 MPH RANGE.
AS THE AFOREMENTIONED UPPER LEVEL TROUGH SWINGS ACROSS THE
PLAINS...A COLD FRONT WILL QUICKLY MOVE THROUGH THE AREA WEDNESDAY
NIGHT. NORTH WINDS OF 15 TO 20 MPH AND COOLER TEMPERATURES CAN BE
EXPECTED BEHIND THE FRONT. I LOWERED HIGH TEMPERATURES BY A FEW
DEGREES FOR THURSDAY...GENERALLY IN THE MID AND UPPER 50S. A CHILLY
MORNING IS FORECAST FRIDAY. SKIES WILL BE MOSTLY CLEAR...DEWPOINTS
WILL BE IN THE SINGLE DIGITS AND SKIES WILL BECOME LIGHT. THE
CURRENT FORECAST HAS LOW TEMPERATURES RANGING FROM THE MID TO UPPER
20S...AND THESE MAY NEED TO LOWERED SLIGHTLY ON FUTURE SHIFTS. A
SLOW WARM UP WILL ENSUE THROUGH NEXT WEEKEND...WITH NO CHANCE OF
PRECIPITATION.
DANIELS
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 44 69 38 66 36 / 0 0 0 0 0
SAN ANGELO 41 71 37 68 35 / 0 0 0 0 0
JUNCTION 43 74 36 71 31 / 5 0 0 0 0
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
99/99/04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
305 AM CST SUN DEC 16 2012
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
305 AM CST SUN DEC 16 2012
THE MAIN FOCUS OVER THE NEXT FEW DAYS IS ON THE DEPARTING
PRECIPITATION TODAY FOLLOWED BY THE CHANCE FOR SNOW ON TUESDAY.
LIGHT RAIN/DRIZZLE AND LIGHT SNOW WILL COME TO AN END FROM WEST TO
EAST TODAY AS A MID LEVEL SHORTWAVE TROUGH PROPAGATES TO THE NORTHEAST
INTO THE GREAT LAKES. AS OF 2 AM...SURFACE OBS AND DUAL POL RADAR
SHOWED THE RAIN/SNOW LINE FROM JUST WEST OF EAU CLAIRE WISCONSIN
DOWN TO WINONA MINNESOTA AND DECORAH IOWA. THE TRANSITION TO LIGHT
SNOW WILL BE RATHER BRIEF AND THEREFORE ANY SNOW ACCUMULATIONS
WILL BE ON THE LIGHT SIDE. EARLIER RUNS OF THE RAP HAD SHOWN THE
POSSIBILITY OF SOME FREEZING DRIZZLE OCCURRING AS THE SNOW CAME TO
AN END...BUT OBSERVATIONS/RADAR UPSTREAM IS NOT SHOWING ANY OF
THIS. DENSE FOG FORMED ACROSS MUCH OF THE REGION OVERNIGHT AS A
RESULT OF HIGH LOW LEVEL MOISTURE DUE TO RECENT RAIN AND SNOW MELT
ALONG WITH THE CORE OF A SURFACE LOW OVERHEAD WHICH PROVIDED
LIGHT TO CALM WINDS. AS THE COLD FRONT EXTENDING SOUTH FROM THE
LOW MOVES THROUGH...WINDS WILL PICK UP AND THE DENSE FOG WILL MIX
OUT WITH VISIBILITY IMPROVING. WITH VISIBILITY STILL LESS THAN A
QUARTER MILE IN NORTH CENTRAL WISCONSIN...WILL LET THE ADVISORY
ROLL FOR NOW WITH IT EXPIRING AT 6 AM...BUT MAY BE ABLE TO CLEAR
IT EARLY.
NOT THE CLEAREST OF WEATHER PATTERNS EXPECTED THROUGH THE NEXT FEW
DAYS WITH SUBTLE SYSTEMS MOVING INTO THE REGION THROUGH THE
SOUTHWEST-WESTERLY FLOW ALOFT. A WEAK MID LEVEL TROUGH WILL MOVE
THROUGH TODAY...BUT WILL ONLY ADD CLOUD COVER TO THE REGION.
16.00Z NAM/GFS SOUNDINGS SHOW THAT THE FORCING IS NOT VERY STRONG
AND THE DRY LAYER IS TOO DEEP FOR SEEDER FEEDER TO PRODUCE SOME
SNOW. A SURFACE RIDGE OF HIGH PRESSURE WILL THEN MOVE THROUGH THE
REGION TONIGHT INTO MONDAY BEFORE THE NEXT SYSTEM TAKES SHAPE IN
THE NORTHERN PLAINS. MUCH OF THE FORCING FOR THIS SYSTEM WILL BE
FROM THE LOW LEVEL WARM AIR ADVECTION...BUT THERE ALSO IS A MID
LEVEL TROUGH THAT ROTATES NORTHWARD INTO SOUTHERN CANADA OVER THE
SAME TIME FRAME. THE 16.00Z ECMWF IS THE STRONGEST WITH HAVING A
SURFACE LOW MOVE THROUGH...BUT OVERALL QPF REMAINS ON THE LIGHT
SIDE AT LESS THAN A TENTH OF AN INCH. PRECIPITATION TYPE WILL
MAINLY BE LIGHT SNOW WITH ANY ACCUMULATIONS LIKELY LESS THAN AN
INCH.
.LONG TERM...WEDNESDAY THROUGH SATURDAY
305 AM CST SUN DEC 16 2012
THE FOCUS FROM MID WEEK INTO NEXT WEEKEND CONTINUES TO BE WITH THE
POTENTIAL FOR A WINTER STORM WEDNESDAY NIGHT INTO THURSDAY. WHILE
THE SUITE OF 16.00Z GUIDANCE STILL ADVERTISES THIS DEEPENING
SURFACE LOW MOVING INTO SOUTHERN LAKE MICHIGAN BY THURSDAY
MORNING...THE TREND IS FOR THE MAJOR IMPACTS FROM THIS SYSTEM TO
BE MORE SO FELT TO THE SOUTH AND EAST OF THE FORECAST AREA. THE
FURTHER EAST THAT THIS SYSTEM CONTINUES TO MOVE...THE LOWER OUR
CHANCES BECOME OF SEEING THE HEAVIEST SNOW BAND OCCUR IN THE
FORECAST AREA. BASED ON 16.00Z GUIDANCE...THE WESTERN EDGE OF THE
SNOW APPEARS TO RUN FROM CENTRAL IOWA THROUGH SOUTHEAST MINNESOTA
AND NORTHWEST WISCONSIN. WHILE THE HEAVIEST SNOW BAND MAY BE TO THE
EAST OF THE FORECAST AREA...THE CHANCES FOR SNOW ACROSS THE REGION
STILL LOOK GOOD...SO HAVE BUMPED UP THE PRECIPITATION PROBABILITIES
WEDNESDAY NIGHT INTO THURSDAY. THIS SYSTEM IS CURRENTLY UP NEAR
THE ALEUTIAN ISLANDS WEST OF ALASKA AND WILL BE INTO CALIFORNIA BY
TUESDAY WHICH IS WHEN WE SHOULD HAVE A BETTER HANDLE ON THE
SYSTEMS TRACK.
BEHIND THIS SYSTEM...COLDER AIR WILL GET PULLED DOWN FROM SOUTHERN
CANADA...BUT IT APPEARS TO BE A FAIRLY SHORT LIVED COLD BURST
BEFORE LOW LEVEL WARM AIR ADVECTION STRENGTHENS OUT OF THE
SOUTHWEST ON SATURDAY. DUE TO THIS...HAVE TRENDED SLIGHTLY WARMER
FOR TEMPERATURES INTO THE WEEKEND.
&&
.AVIATION...THROUGH 06Z MONDAY
1126 PM CST SAT DEC 15 2012
SURFACE LOW NOW OVER WESTERN WISCONSIN WILL CONTINUE TO PULL
NORTHEAST TONIGHT. WRAP AROUND MOISTURE ON ITS BACK SIDE WAS
PUSHING THROUGH SOUTHEAST MINNESOTA AND WILL PASS ACROSS THE TAF
SITES THROUGH THE OVERNIGHT HOURS. VISIBILITIES HAVE IMPROVED AT
KRST DUE TO THE WIND SHIFT AND LIGHT PRECIPITATION. EXPECT THIS TO
OCCUR AT KLSE AROUND 08Z. THE TRANSITION FROM LIQUID TO SNOW WILL
OCCUR AT KRST BETWEEN 06Z-08Z AND AT KLSE BETWEEN 10Z-12Z. ONE
CONCERN IS RAP AND NAM BUFKIT SOUNDINGS SHOWING A LOSS OF ICE AND
THUS MAYBE SOME LIGHT FZDZ FOR A PERIOD OF TIME LATER THIS MORNING
BEFORE THE PRECIPITATION ENDS AND DID INCLUDE A TEMPO GROUP AT
BOTH SITES. OTHERWISE...CEILINGS WILL REMAIN IFR THROUGH AT LEAST
18Z AND MAY RISE INTO THE LOWER MVFR CATEGORY FOR THE AFTERNOON.
WITH THE MOISTURE TRAPPED UNDER THE INVERSION...SOME CONCERN AS TO
LOWERING CEILINGS/VISIBILITIES ONCE AGAIN AFTER 00Z AS COLUMN
COOLS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
305 AM CST SUN DEC 16 2012
WI...DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR WIZ017-
029-034-042>044.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
948 AM CST SUN DEC 16 2012
.UPDATE...
ISSUED AT 944 AM CST SUN DEC 16 2012
THE DENSE FOG ADVISORY WAS UPDATED TO REFLECT THE SOUTHWEST
ADVECTION OF THE FOG DOWN INTO THE LIBERAL AND MEADE AREAS. HRRR
AND RAP MODELS SUGGEST VISIBLITIES WILL STAY DOWN UNTIL AROUND
17Z...WITH ONLY SLOW IMPROVEMENT IN VISIBILITY AND CEILING THROUGH
MIDDAY/EARLY AFTERNOON. THIS WILL IMPACT TEMPERATURES TODAY AND
HAVE HAD TO DRASTICALLY LOWER THE TEMPERATURES FOR TODAY FROM THE
ARKANSAS RIVER SOUTH TO THE OKLAHOMA BORDER AS MESOSCALE LOW WILL
TRAVEL ALONG THE KS-OK BORDER TODAY KEEPING COOL, MOIST NORTHEAST
WINDS IN PLACE PRETTY MUCH ALL DAY.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 341 AM CST SUN DEC 16 2012
THE COLORADO SHORTWAVE HAS BEEN PROGRESSING STEADILY EASTWARD PER
SATELLITE LOOPS. EXTRAPOLATING IT AT ITS CURRENT SPEED WOULD PUT IT
OVER SOUTH CENTRAL KANSAS BY 18Z. THE 00Z NAM HAS A PRETTY GOOD
HANDLE ON THIS. THIS MODEL ALSO KEEPS ANY PRECIPITATION ASSOCIATED
WITH THIS WAVE OVER FAR NORTHERN KANSAS THIS MORNING. THE LATEST
RUNS OF THE RUC13 ARE ALSO DRY BUT IT DOES TRY TO DEVELOP SOME
LIGHT PRECIPITATION OVER SOUTH CENTRAL KANSAS TOWARD MIDDAY. BASED
ON CURRENT RADAR TRENDS, HAVE OPTED TO LOWER POPS ACROSS WEST
CENTRAL KANSAS THIS MORNING AND REMOVE THE MENTION OF SPRINKLES
FROM THE FORECAST. THIS WILL HAVE TO BE WATCHED FOR THE NEXT FEW
HOURS FOR ANY CHANGES IN THE CURRENT RADAR TRENDS.
ONCE THE FIRST WAVE MOVES OUT OF WESTERN KANSAS, WE SHOULD SEE AN
INCREASE IN SUNSHINE FOR A WHILE UNTIL CIRRUS ASSOCIATED WITH THE
NEXT WAVE BEGINS TO MOVE IN FROM THE WEST. THIS COULD HELP BOOST
TEMPERATURES UP A LITTLE THIS AFTERNOON AND HAVE ADJUSTED TODAY`S
HIGH TEMPERATURES UP A BIT ESPECIALLY OVER CENTRAL KANSAS.
THE NEXT WAVE WILL MOVE OUT OVER THE CENTRAL HIGH PLAINS THIS
EVENING AND SHOULD BE EAST OF THE AREA BY MIDNIGHT. AM NOT
EXPECTING ANY SIGNIFICANT PRECIPITATION WITH THIS WAVE AS WELL.
HAVE LOWERED SUNDAY NIGHTS LOW TEMPERATURES A FEW DEGREES CLOSER
TO THE NAM MOS NUMBERS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 403 AM CST SUN DEC 16 2012
THE MAJOR ADJUSTMENTS TO THE EXTENDED FORECAST OCCURRED IN THE
WEDNESDAY AND WEDNESDAY NIGHT TIMEFRAME, WHEN THE POTENTIAL FOR A
DYNAMIC LOW TO DEVELOP OVER THE HIGH PLAINS, BRINGING GOOD POTENTIAL
FOR WINDY AND SNOWY CONDITIONS.
THE RELATIVELY MILD TEMPERATURES WILL CONTINUE ON MONDAY AND
TUESDAY, AS A FAST MOVING PACIFIC JET SPREADS INTO THE NATIONS
INTERIOR, FORMING A PROGRESSIVE FLAT RIDGE THAT LIFTS INTO THE
EASTERN HALF OF THE NATION BY WEDNESDAY. THE POSITION OF THE JET AND
THE RELATIVE HUMIDITY FIELDS OF MODEL LOWER AND MID TROPOSPHERIC
LAYERS SUGGEST MOSTLY SUNNY CONDITIONS SHOULD BE EXPERIENCED ACROSS
WESTERN KANSAS MONDAY AND TUESDAY. EARLY IN THE PERIOD LIGHT NORTHERLY
WINDS ASSOCIATED WITH THE RETREATING NORTHERN PLAINS HIGH WILL
BECOME MORE SOUTHWESTERLY BY TUESDAY AS SURFACE TROUGHING DEVELOPS
ACROSS THE DAKOTAS. MODEL CONSENSUS CONTINUES TO SUPPORT HIGHS
REACHING THE 50S. TUESDAY MAY BE AROUND 5 DEGREES WARMER WITH
TEMPERATURES REACHING AROUND 60 DEGREES WITH WEAK DOWNSLOPING
SURFACE WINDS, ESPECIALLY ACROSS SOUTH CENTRAL KANSAS.
THE UPPER FLOW WILL BE RAPIDLY DEVELOPING INTO A STRONGLY AMPLIFIED
UPPER TROUGH EARLY WEDNESDAY, AND DRIVE A COLD FRONT THROUGH WESTERN
KANSAS WEDNESDAY MORNING. BOTH THE ECMWF AND GFS DEVELOP A SURFACE
TO 700 LOW POLEWARD TILTED FROM NORTHERN OKLAHOMA INTO KANSAS. THIS
SHOULD PRODUCE A PERIOD OF MID LEVEL FRONTOGENETIC FORCING WITH COLD
ENOUGH AIR FOR SNOW ACCUMULATION TO DEVELOP BEHIND THE SURFACE COLD
FRONT. THE INTENSITY AND LOCATIONS ARE HOWEVER STILL MUCH OF AN
UNCERTAINTY AT THIS TIME. REGARDLESS, WE`VE INCREASED POPS IN THE
WEDNESDAY TIMEFRAME AND FOLLOWED THE COLDER MODEL TRENDS FOR
TEMPERATURES INTO THURSDAY AND THURSDAY NIGHT. WE USED A SLIGHTLY
DOWNWARD ADJUSTED ECMWF QPF FORECAST. BASED ON TEMPERATURES NOT
EXPECTED TO BE EXCEEDING COLD WEDNESDAY, AND WINDY CONDITIONS BEHIND
THE BOUNDARY, A CONSERVATIVE 8:1 SNOW RATIO WAS USED FOR THE SNOW
ACCUMULATION. THAT PRODUCES SNOWFALL AMOUNTS RANGING FROM AROUND A
HALF INCH TO AN INCH AN A HALF. ADDITIONAL MODEL RUNS MAY SHED MORE
INSIGHT ON WHETHER SIGNIFICANT IMPACTS MAY OCCUR, BUT WITH THESE
KIND OF SNOW TOTALS AND WIND SPEEDS, HEADLINES DON`T APPEAR LIKELY
AT THIS TIME.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 544 AM CST SUN DEC 16 2012
NORTHEAST UPSLOPE FLOW ACROSS CENTRAL KANSAS IS CREATING WIDESPREAD
DENSE FOG, EXPANDING WESTWARD THIS MORNING. OBSERVATIONS FROM GREAT
BEND AND SURROUNDING LOCATIONS CONFIRMED THE LOW VISIBILITIES, AND
THE AREA OF EXPANSIVE FOG CAN BE SEEN ON THE 11-3.9 MICRON SATELLITE
CHANNEL. THIS FOG WILL LIKELY AFFECT THE KDDC TERMINAL PERHAPS
THROUGH MID MORNING. LESS CONFIDENCE EXIST OF THE SAME IMPACTS AT
KGCK AT THIS TIME.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 42 24 54 29 / 10 10 0 0
GCK 44 22 52 28 / 10 10 0 0
EHA 43 25 54 31 / 10 0 0 0
LBL 39 22 54 29 / 10 10 0 0
HYS 44 24 52 28 / 10 10 0 0
P28 43 29 57 30 / 10 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 11 AM CST THIS MORNING FOR KSZ046-
064>066-076>081-086>090.
&&
$$
UPDATE...UMSCHEID
SHORT TERM...GERARD
LONG TERM...RUSSELL
AVIATION...RUSSELL
AREA FORECAST DISCUSSION
NWS TOPEKA KS
626 AM CST SUN DEC 16 2012
...UPDATE TO AVIATION...
.UPDATE...
AFTER MAKING SOME CALLS ACROSS EAST CENTRAL KS...IT APPEARS AS
THOUGH THE HIGH CLOUDS HAVE NOT DIMINISHED THE DENSE FOG. NOW THAT
SKIES ARE CLEARING OUT AGAIN...VISIBILITIES ARE LIKELY TO REMAIN
DOWN TO A QUARTER OF A MILE...AND WE HAVE ISSUED A DENSE FOG
ADVISORY THROUGH MID MORNING.
&&
.DISCUSSION...
09Z WATER VAPOR IMAGERY SHOWS A COMPACT SHORTWAVE OVER THE NM/CO
ROCKIES. A SECOND SHORTWAVE WAS NOTED OVER THE PACIFIC NORTHWEST. AT
THE SURFACE...WEAK RIDGING WAS SEEN FROM THE NORTHERN PLAINS INTO
NORTHERN KS.
FOR TODAY THROUGH MONDAY...A RATHER DISORGANIZED CYCLONIC FLOW IS
PROGGED TO AFFECT THE AREA WITH THE SHORTWAVES NOTED ON WATER VAPOR
TRAVERSING THE AREA. INITIALLY FORECAST SOUNDINGS FROM THE RAP AND
NAM SHOW SOME MID LEVEL DRY AIR THAT HAS TO BE OVERCOME WITH THE
BETTER MID LEVEL SATURATION REMAINING JUST NORTH OF THE STATE LINE.
WITH THIS IN MIND AND THE MODELS SHOWING THE SHORTWAVE OVER NM/CO
WEAKENING AS IT MOVES EAST...WILL MAINTAIN THE MENTION OF FLURRIES
AND OR SPRINKLES ACROSS THE FAR NORTHERN COUNTIES THINKING THAT ANY
PRECIP WILL NOT BE MEASURABLE. IT SEEMS THAT DRY LOW LEVELS FOR
TONIGHT AND MONDAY MORNING WILL ALSO LIMIT PRECIP CHANCES AS THE
WAVE OVER THE PACIFIC NORTHWEST KICKS THE LONGWAVE TROUGH EAST. WITH
WEAK COLD AIR ADVECTION AND INCREASING CLOUDS...TEMPS SHOULD BE
COOLER TODAY WITH HIGHS GENERALLY IN THE 40S. LOW LEVEL WINDS ARE
EXPECTED TO TURN BACK FROM THE SOUTH AND SOUTHWEST FOR MONDAY...SO
TEMPS SHOULD BEGIN TO MODERATE.
THE NEXT CHANCE FOR MEASURABLE PRECIP CONTINUES TO LOOK LIKE IT WILL
OCCUR WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT...AND WE MAY END UP
SEEING THE FIRST SNOWFALL OF THE WINTER. THE GFS AND ECMWF APPEAR TO
BE CONVERGING ON A PROGRESSIVE SYSTEM MOVING ACROSS THE PLAINS AS
THE NEXT SHORTWAVE TROUGH PROPAGATES ACROSS NORTH AMERICA. WHILE THE
GFS IS NOTABLY FASTER WITH THE SURFACE LOW...THE TRACKS OF THE
SYSTEM ARE SIMILAR FROM BOTH MODEL SOLUTIONS. ALSO BECAUSE OF THE
PROGRESSIVE NATURE OF THE SYSTEM AND BOTH MODELS DEEPENING THE
SURFACE LOW AS IT PASSES SOUTHEAST OF THE FORECAST AREA...THE COLD
AIR IS QUICKER TO PUSH SOUTH DURING THE AFTERNOON WEDNESDAY WITH
TEMPS POTENTIALLY FALLING DURING THE AFTERNOON. THERE APPEARS TO BE
DECENT QG VECTOR CONVERGENCE WITH THE SYSTEM AND MODELS SHOW GOOD
MID LEVEL FRONTOGENESIS NORTHWEST OF THE SURFACE LOW TRACK. GIVEN
THE TEMP PROFILES RAPIDLY COOLING AND THE MESOSCALE FORCING...THINK
THERE COULD BE A BAND OF SNOW FORM LATE WEDNESDAY AFTERNOON AND
THROUGH THE NIGHT. CROSS SECTIONS FROM THE GFS AND ECMWF SUGGEST THE
STRONGER VERTICAL MOTION WILL OCCUR BETWEEN 00 AND 06Z THUR WITH DRY
AIR AND SUBSIDENCE QUICKLY FILLING IN TOWARDS 12Z. BECAUSE OF THE
PROGRESSIVE NATURE OF THE SYSTEM...SNOW AMOUNTS LOOK TO BE ON THE
ORDER OF A COUPLE INCHES.
SOMEWHAT ZONAL FLOW DEVELOPS IN THE WAKE OF THE WEDNESDAY NIGHT
SYSTEM...WITH THE UPPER LEVEL JET SETTING UP ACROSS THE SOUTHERN
HALF OF THE COUNTRY. THIS SHOULD KEEP A DRY AND COOL AIRMASS OVER
THE PLAINS FOR THURSDAY NIGHT THROUGH SATURDAY.
WOLTERS
&&
.AVIATION...
PRIMARILY MVFR CONDITIONS WILL PERSIST AT TAF SITES THROUGH AROUND
15Z AS REDUCED VISIBILITIES AND LOW STRATUS MOVE IN FROM THE NORTH.
TOP/FOE MAY REMAIN IN LOW CEILINGS LONGER AND EVENTUALLY IMPROVE
BY 18Z...WHEN ALL TAF SITES ARE ANTICIPATED TO BE VFR.
BLAIR
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR KSZ054>056-
058-059.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
545 AM CST SUN DEC 16 2012
...UPDATED FOR AVIATION...
.SYNOPSIS...
ISSUED AT 341 AM CST SUN DEC 16 2012
THE 00Z UPPER AIR ANALYSIS SHOWED A SOMEWHAT SPLIT FLOW PATTERN
OVER WESTERN NORTH AMERICA. IN THE NORTH, SHORTWAVE TROUGHS WERE
MOVING OVER THE CENTRAL CANADIAN PRAIRIE AND INTO BRITISH COLUMBIA.
FARTHER SOUTH, THE SHORTWAVE TROUGH THAT MOVED OUT OF THE CENTRAL
HIGH PLAINS SUNDAY MORNING WAS OVER THE GREAT LAKES REGION. FARTHER
WEST, A COMPACT SHORTWAVE WAS MOVING ACROSS SOUTHERN COLORADO WHILE
ANOTHER WAVE WAS ON ITS HEELS OVER THE GREAT BASIN INTO ARIZONA.
THE REGIONAL RADAR MOSAIC SHOWS A SMALL AREA OF LIGHT TO MODERATE
SNOW OVER FAR SOUTHWEST NEBRASKA, WHICH APPEARS TO BE FORCED BY
SOME MID LEVEL FRONTOGENESIS. RADAR RETURNS OVER SOUTHERN COLORADO
HAVE BEEN FAIRLY LIGHT SO FAR THIS MORNING.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 341 AM CST SUN DEC 16 2012
THE COLORADO SHORTWAVE HAS BEEN PROGRESSING STEADILY EASTWARD PER
SATELLITE LOOPS. EXTRAPOLATING IT AT ITS CURRENT SPEED WOULD PUT IT
OVER SOUTH CENTRAL KANSAS BY 18Z. THE 00Z NAM HAS A PRETTY GOOD
HANDLE ON THIS. THIS MODEL ALSO KEEPS ANY PRECIPITATION ASSOCIATED
WITH THIS WAVE OVER FAR NORTHERN KANSAS THIS MORNING. THE LATEST
RUNS OF THE RUC13 ARE ALSO DRY BUT IT DOES TRY TO DEVELOP SOME
LIGHT PRECIPITATION OVER SOUTH CENTRAL KANSAS TOWARD MIDDAY. BASED
ON CURRENT RADAR TRENDS, HAVE OPTED TO LOWER POPS ACROSS WEST
CENTRAL KANSAS THIS MORNING AND REMOVE THE MENTION OF SPRINKLES
FROM THE FORECAST. THIS WILL HAVE TO BE WATCHED FOR THE NEXT FEW
HOURS FOR ANY CHANGES IN THE CURRENT RADAR TRENDS.
ONCE THE FIRST WAVE MOVES OUT OF WESTERN KANSAS, WE SHOULD SEE AN
INCREASE IN SUNSHINE FOR A WHILE UNTIL CIRRUS ASSOCIATED WITH THE
NEXT WAVE BEGINS TO MOVE IN FROM THE WEST. THIS COULD HELP BOOST
TEMPERATURES UP A LITTLE THIS AFTERNOON AND HAVE ADJUSTED TODAY`S
HIGH TEMPERATURES UP A BIT ESPECIALLY OVER CENTRAL KANSAS.
THE NEXT WAVE WILL MOVE OUT OVER THE CENTRAL HIGH PLAINS THIS
EVENING AND SHOULD BE EAST OF THE AREA BY MIDNIGHT. AM NOT
EXPECTING ANY SIGNIFICANT PRECIPITATION WITH THIS WAVE AS WELL.
HAVE LOWERED SUNDAY NIGHTS LOW TEMPERATURES A FEW DEGREES CLOSER
TO THE NAM MOS NUMBERS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 403 AM CST SUN DEC 16 2012
THE MAJOR ADJUSTMENTS TO THE EXTENDED FORECAST OCCURRED IN THE
WEDNESDAY AND WEDNESDAY NIGHT TIMEFRAME, WHEN THE POTENTIAL FOR A
DYNAMIC LOW TO DEVELOP OVER THE HIGH PLAINS, BRINGING GOOD POTENTIAL
FOR WINDY AND SNOWY CONDITIONS.
THE RELATIVELY MILD TEMPERATURES WILL CONTINUE ON MONDAY AND
TUESDAY, AS A FAST MOVING PACIFIC JET SPREADS INTO THE NATIONS
INTERIOR, FORMING A PROGRESSIVE FLAT RIDGE THAT LIFTS INTO THE
EASTERN HALF OF THE NATION BY WEDNESDAY. THE POSITION OF THE JET AND
THE RELATIVE HUMIDITY FIELDS OF MODEL LOWER AND MID TROPOSPHERIC
LAYERS SUGGEST MOSTLY SUNNY CONDITIONS SHOULD BE EXPERIENCED ACROSS
WESTERN KANSAS MONDAY AND TUESDAY. EARLY IN THE PERIOD LIGHT NORTHERLY
WINDS ASSOCIATED WITH THE RETREATING NORTHERN PLAINS HIGH WILL
BECOME MORE SOUTHWESTERLY BY TUESDAY AS SURFACE TROUGHING DEVELOPS
ACROSS THE DAKOTAS. MODEL CONSENSUS CONTINUES TO SUPPORT HIGHS
REACHING THE 50S. TUESDAY MAY BE AROUND 5 DEGREES WARMER WITH
TEMPERATURES REACHING AROUND 60 DEGREES WITH WEAK DOWNSLOPING
SURFACE WINDS, ESPECIALLY ACROSS SOUTH CENTRAL KANSAS.
THE UPPER FLOW WILL BE RAPIDLY DEVELOPING INTO A STRONGLY AMPLIFIED
UPPER TROUGH EARLY WEDNESDAY, AND DRIVE A COLD FRONT THROUGH WESTERN
KANSAS WEDNESDAY MORNING. BOTH THE ECMWF AND GFS DEVELOP A SURFACE
TO 700 LOW POLEWARD TILTED FROM NORTHERN OKLAHOMA INTO KANSAS. THIS
SHOULD PRODUCE A PERIOD OF MID LEVEL FRONTOGENETIC FORCING WITH COLD
ENOUGH AIR FOR SNOW ACCUMULATION TO DEVELOP BEHIND THE SURFACE COLD
FRONT. THE INTENSITY AND LOCATIONS ARE HOWEVER STILL MUCH OF AN
UNCERTAINTY AT THIS TIME. REGARDLESS, WE`VE INCREASED POPS IN THE
WEDNESDAY TIMEFRAME AND FOLLOWED THE COLDER MODEL TRENDS FOR
TEMPERATURES INTO THURSDAY AND THURSDAY NIGHT. WE USED A SLIGHTLY
DOWNWARD ADJUSTED ECMWF QPF FORECAST. BASED ON TEMPERATURES NOT
EXPECTED TO BE EXCEEDING COLD WEDNESDAY, AND WINDY CONDITIONS BEHIND
THE BOUNDARY, A CONSERVATIVE 8:1 SNOW RATIO WAS USED FOR THE SNOW
ACCUMULATION. THAT PRODUCES SNOWFALL AMOUNTS RANGING FROM AROUND A
HALF INCH TO AN INCH AN A HALF. ADDITIONAL MODEL RUNS MAY SHED MORE
INSIGHT ON WHETHER SIGNIFICANT IMPACTS MAY OCCUR, BUT WITH THESE
KIND OF SNOW TOTALS AND WIND SPEEDS, HEADLINES DON`T APPEAR LIKELY
AT THIS TIME.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 544 AM CST SUN DEC 16 2012
NORTHEAST UPSLOPE FLOW ACROSS CENTRAL KANSAS IS CREATING WIDESPREAD
DENSE FOG, EXPANDING WESTWARD THIS MORNING. OBSERVATIONS FROM GREAT
BEND AND SURROUNDING LOCATIONS CONFIRMED THE LOW VISIBILITIES, AND
THE AREA OF EXPANSIVE FOG CAN BE SEEN ON THE 11-3.9 MICRON SATELLITE
CHANNEL. THIS FOG WILL LIKELY AFFECT THE KDDC TERMINAL PERHAPS
THROUGH MID MORNING. LESS CONFIDENCE EXIST OF THE SAME IMPACTS AT
KGCK AT THIS TIME.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 47 24 54 29 / 10 10 0 0
GCK 47 22 52 28 / 10 10 0 0
EHA 49 25 54 31 / 10 0 0 0
LBL 50 22 54 29 / 10 10 0 0
HYS 42 24 52 28 / 10 10 0 0
P28 51 29 57 30 / 10 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR KSZ031-045-
046-064>066-078>081-089-090.
&&
$$
SYNOPSIS...GERARD
SHORT TERM...GERARD
LONG TERM...RUSSELL
AVIATION...RUSSELL
AREA FORECAST DISCUSSION...UPDATED
NWS TOPEKA KS
420 AM CST SUN DEC 16 2012
.UPDATE...
AFTER MAKING SOME CALLS ACROSS EAST CENTRAL KS...IT APPEARS AS
THOUGH THE HIGH CLOUDS HAVE NOT DIMINISHED THE DENSE FOG. NOW THAT
SKIES ARE CLEARING OUT AGAIN...VISIBILITIES ARE LIKELY TO REMAIN
DOWN TO A QUARTER OF A MILE...AND WE HAVE ISSUED A DENSE FOG
ADVISORY THROUGH MID MORNING.
&&
.DISCUSSION...
09Z WATER VAPOR IMAGERY SHOWS A COMPACT SHORTWAVE OVER THE NM/CO
ROCKIES. A SECOND SHORTWAVE WAS NOTED OVER THE PACIFIC NORTHWEST. AT
THE SURFACE...WEAK RIDGING WAS SEEN FROM THE NORTHERN PLAINS INTO
NORTHERN KS.
FOR TODAY THROUGH MONDAY...A RATHER DISORGANIZED CYCLONIC FLOW IS
PROGGED TO AFFECT THE AREA WITH THE SHORTWAVES NOTED ON WATER VAPOR
TRAVERSING THE AREA. INITIALLY FORECAST SOUNDINGS FROM THE RAP AND
NAM SHOW SOME MID LEVEL DRY AIR THAT HAS TO BE OVERCOME WITH THE
BETTER MID LEVEL SATURATION REMAINING JUST NORTH OF THE STATE LINE.
WITH THIS IN MIND AND THE MODELS SHOWING THE SHORTWAVE OVER NM/CO
WEAKENING AS IT MOVES EAST...WILL MAINTAIN THE MENTION OF FLURRIES
AND OR SPRINKLES ACROSS THE FAR NORTHERN COUNTIES THINKING THAT ANY
PRECIP WILL NOT BE MEASURABLE. IT SEEMS THAT DRY LOW LEVELS FOR
TONIGHT AND MONDAY MORNING WILL ALSO LIMIT PRECIP CHANCES AS THE
WAVE OVER THE PACIFIC NORTHWEST KICKS THE LONGWAVE TROUGH EAST. WITH
WEAK COLD AIR ADVECTION AND INCREASING CLOUDS...TEMPS SHOULD BE
COOLER TODAY WITH HIGHS GENERALLY IN THE 40S. LOW LEVEL WINDS ARE
EXPECTED TO TURN BACK FROM THE SOUTH AND SOUTHWEST FOR MONDAY...SO
TEMPS SHOULD BEGIN TO MODERATE.
THE NEXT CHANCE FOR MEASURABLE PRECIP CONTINUES TO LOOK LIKE IT WILL
OCCUR WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT...AND WE MAY END UP
SEEING THE FIRST SNOWFALL OF THE WINTER. THE GFS AND ECMWF APPEAR TO
BE CONVERGING ON A PROGRESSIVE SYSTEM MOVING ACROSS THE PLAINS AS
THE NEXT SHORTWAVE TROUGH PROPAGATES ACROSS NORTH AMERICA. WHILE THE
GFS IS NOTABLY FASTER WITH THE SURFACE LOW...THE TRACKS OF THE
SYSTEM ARE SIMILAR FROM BOTH MODEL SOLUTIONS. ALSO BECAUSE OF THE
PROGRESSIVE NATURE OF THE SYSTEM AND BOTH MODELS DEEPENING THE
SURFACE LOW AS IT PASSES SOUTHEAST OF THE FORECAST AREA...THE COLD
AIR IS QUICKER TO PUSH SOUTH DURING THE AFTERNOON WEDNESDAY WITH
TEMPS POTENTIALLY FALLING DURING THE AFTERNOON. THERE APPEARS TO BE
DECENT QG VECTOR CONVERGENCE WITH THE SYSTEM AND MODELS SHOW GOOD
MID LEVEL FRONTOGENESIS NORTHWEST OF THE SURFACE LOW TRACK. GIVEN
THE TEMP PROFILES RAPIDLY COOLING AND THE MESOSCALE FORCING...THINK
THERE COULD BE A BAND OF SNOW FORM LATE WEDNESDAY AFTERNOON AND
THROUGH THE NIGHT. CROSS SECTIONS FROM THE GFS AND ECMWF SUGGEST THE
STRONGER VERTICAL MOTION WILL OCCUR BETWEEN 00 AND 06Z THUR WITH DRY
AIR AND SUBSIDENCE QUICKLY FILLING IN TOWARDS 12Z. BECAUSE OF THE
PROGRESSIVE NATURE OF THE SYSTEM...SNOW AMOUNTS LOOK TO BE ON THE
ORDER OF A COUPLE INCHES.
SOMEWHAT ZONAL FLOW DEVELOPS IN THE WAKE OF THE WEDNESDAY NIGHT
SYSTEM...WITH THE UPPER LEVEL JET SETTING UP ACROSS THE SOUTHERN
HALF OF THE COUNTRY. THIS SHOULD KEEP A DRY AND COOL AIRMASS OVER
THE PLAINS FOR THURSDAY NIGHT THROUGH SATURDAY.
WOLTERS
&&
.AVIATION...
MOSTLY CLEAR SKIES ACROSS THE TERMINALS HAS LED TO MVFR/IFR FOG TO
DEVELOP OVER THE PAST HOUR EXCEPT IN KTOP. WITH LIGHT WINDS...EXPECT
MORE IFR/VLIFR FOG TO DEVELOP NEXT 1-3 HOURS. HOWEVER...AFT 08-09Z
SOME MID AND HIGH CLOUDS MAY BE OFFSETTING FACTOR ALONG WITH DRY AIR
JUST ABOVE THE FOG...SO HAVE INCREASED VSBYS AFT THAT TIME THROUGH
ON THRU 14Z. BEYOND 14Z HAVE CONTINUED VFR CONDITIONS WITH LIGHT
NORTH/NORTHEAST WINDS AND MID LEVEL AC DECK AROUND 12 KFT.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY FOR KSZ054>056-058-059 UNTIL 9 AM TODAY.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
404 AM CST SUN DEC 16 2012
.SYNOPSIS...
ISSUED AT 341 AM CST SUN DEC 16 2012
THE 00Z UPPER AIR ANALYSIS SHOWED A SOMEWHAT SPLIT FLOW PATTERN
OVER WESTERN NORTH AMERICA. IN THE NORTH, SHORTWAVE TROUGHS WERE
MOVING OVER THE CENTRAL CANADIAN PRAIRIE AND INTO BRITISH COLUMBIA.
FARTHER SOUTH, THE SHORTWAVE TROUGH THAT MOVED OUT OF THE CENTRAL
HIGH PLAINS SUNDAY MORNING WAS OVER THE GREAT LAKES REGION. FARTHER
WEST, A COMPACT SHORTWAVE WAS MOVING ACROSS SOUTHERN COLORADO WHILE
ANOTHER WAVE WAS ON ITS HEELS OVER THE GREAT BASIN INTO ARIZONA.
THE REGIONAL RADAR MOSAIC SHOWS A SMALL AREA OF LIGHT TO MODERATE
SNOW OVER FAR SOUTHWEST NEBRASKA, WHICH APPEARS TO BE FORCED BY
SOME MID LEVEL FRONTOGENESIS. RADAR RETURNS OVER SOUTHERN COLORADO
HAVE BEEN FAIRLY LIGHT SO FAR THIS MORNING.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 341 AM CST SUN DEC 16 2012
THE COLORADO SHORTWAVE HAS BEEN PROGRESSING STEADILY EASTWARD PER
SATELLITE LOOPS. EXTRAPOLATING IT AT ITS CURRENT SPEED WOULD PUT IT
OVER SOUTH CENTRAL KANSAS BY 18Z. THE 00Z NAM HAS A PRETTY GOOD
HANDLE ON THIS. THIS MODEL ALSO KEEPS ANY PRECIPITATION ASSOCIATED
WITH THIS WAVE OVER FAR NORTHERN KANSAS THIS MORNING. THE LATEST
RUNS OF THE RUC13 ARE ALSO DRY BUT IT DOES TRY TO DEVELOP SOME
LIGHT PRECIPITATION OVER SOUTH CENTRAL KANSAS TOWARD MIDDAY. BASED
ON CURRENT RADAR TRENDS, HAVE OPTED TO LOWER POPS ACROSS WEST
CENTRAL KANSAS THIS MORNING AND REMOVE THE MENTION OF SPRINKLES
FROM THE FORECAST. THIS WILL HAVE TO BE WATCHED FOR THE NEXT FEW
HOURS FOR ANY CHANGES IN THE CURRENT RADAR TRENDS.
ONCE THE FIRST WAVE MOVES OUT OF WESTERN KANSAS, WE SHOULD SEE AN
INCREASE IN SUNSHINE FOR A WHILE UNTIL CIRRUS ASSOCIATED WITH THE
NEXT WAVE BEGINS TO MOVE IN FROM THE WEST. THIS COULD HELP BOOST
TEMPERATURES UP A LITTLE THIS AFTERNOON AND HAVE ADJUSTED TODAY`S
HIGH TEMPERATURES UP A BIT ESPECIALLY OVER CENTRAL KANSAS.
THE NEXT WAVE WILL MOVE OUT OVER THE CENTRAL HIGH PLAINS THIS
EVENING AND SHOULD BE EAST OF THE AREA BY MIDNIGHT. AM NOT
EXPECTING ANY SIGNIFICANT PRECIPITATION WITH THIS WAVE AS WELL.
HAVE LOWERED SUNDAY NIGHTS LOW TEMPERATURES A FEW DEGREES CLOSER
TO THE NAM MOS NUMBERS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 403 AM CST SUN DEC 16 2012
THE MAJOR ADJUSTMENTS TO THE EXTENDED FORECAST OCCURRED IN THE
WEDNESDAY AND WEDNESDAY NIGHT TIMEFRAME, WHEN THE POTENTIAL FOR A
DYNAMIC LOW TO DEVELOP OVER THE HIGH PLAINS, BRINGING GOOD POTENTIAL
FOR WINDY AND SNOWY CONDITIONS.
THE RELATIVELY MILD TEMPERATURES WILL CONTINUE ON MONDAY AND
TUESDAY, AS A FAST MOVING PACIFIC JET SPREADS INTO THE NATIONS
INTERIOR, FORMING A PROGRESSIVE FLAT RIDGE THAT LIFTS INTO THE
EASTERN HALF OF THE NATION BY WEDNESDAY. THE POSITION OF THE JET AND
THE RELATIVE HUMIDITY FIELDS OF MODEL LOWER AND MID TROPOSPHERIC
LAYERS SUGGEST MOSTLY SUNNY CONDITIONS SHOULD BE EXPERIENCED ACROSS
WESTERN KANSAS MONDAY AND TUESDAY. EARLY IN THE PERIOD LIGHT NORTHERLY
WINDS ASSOCIATED WITH THE RETREATING NORTHERN PLAINS HIGH WILL
BECOME MORE SOUTHWESTERLY BY TUESDAY AS SURFACE TROUGHING DEVELOPS
ACROSS THE DAKOTAS. MODEL CONSENSUS CONTINUES TO SUPPORT HIGHS
REACHING THE 50S. TUESDAY MAY BE AROUND 5 DEGREES WARMER WITH
TEMPERATURES REACHING AROUND 60 DEGREES WITH WEAK DOWNSLOPING
SURFACE WINDS, ESPECIALLY ACROSS SOUTH CENTRAL KANSAS.
THE UPPER FLOW WILL BE RAPIDLY DEVELOPING INTO A STRONGLY AMPLIFIED
UPPER TROUGH EARLY WEDNESDAY, AND DRIVE A COLD FRONT THROUGH WESTERN
KANSAS WEDNESDAY MORNING. BOTH THE ECMWF AND GFS DEVELOP A SURFACE
TO 700 LOW POLEWARD TILTED FROM NORTHERN OKLAHOMA INTO KANSAS. THIS
SHOULD PRODUCE A PERIOD OF MID LEVEL FRONTOGENETIC FORCING WITH COLD
ENOUGH AIR FOR SNOW ACCUMULATION TO DEVELOP BEHIND THE SURFACE COLD
FRONT. THE INTENSITY AND LOCATIONS ARE HOWEVER STILL MUCH OF AN
UNCERTAINTY AT THIS TIME. REGARDLESS, WE`VE INCREASED POPS IN THE
WEDNESDAY TIMEFRAME AND FOLLOWED THE COLDER MODEL TRENDS FOR
TEMPERATURES INTO THURSDAY AND THURSDAY NIGHT. WE USED A SLIGHTLY
DOWNWARD ADJUSTED ECMWF QPF FORECAST. BASED ON TEMPERATURES NOT
EXPECTED TO BE EXCEEDING COLD WEDNESDAY, AND WINDY CONDITIONS BEHIND
THE BOUNDARY, A CONSERVATIVE 8:1 SNOW RATIO WAS USED FOR THE SNOW
ACCUMULATION. THAT PRODUCES SNOWFALL AMOUNTS RANGING FROM AROUND A
HALF INCH TO AN INCH AN A HALF. ADDITIONAL MODEL RUNS MAY SHED MORE
INSIGHT ON WHETHER SIGNIFICANT IMPACTS MAY OCCUR, BUT WITH THESE
KIND OF SNOW TOTALS AND WIND SPEEDS, HEADLINES DON`T APPEAR LIKELY
AT THIS TIME.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1209 AM CST SUN DEC 16 2012
AN UPPER LEVEL DISTURBANCE WILL MOVE OUT OF SOUTHERN COLORADO ACROSS
SOUTHERN KANSAS LATE TONIGHT THROUGH SUNDAY MORNING. THIS WILL BRING
SCATTERED TO OCCASIONALLY BROKEN MID TO HIGH LEVEL CLOUDS, ALONG
WITH POSSIBLE SPRINKLES, ACROSS WESTERN KANSAS THROUGH THE FIRST
PART OF THE PERIOD. THERE IS A VERY SMALL CHANCE FOR A BRIEF PERIOD
OF IFR CIGS AT GARDEN CITY AND DODGE CITY BETWEEN 12Z AND 15Z BUT
CONFIDENCE IS TOO LOW TO ADD IT TO THE TAFS AT THIS TIME.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 47 24 54 29 / 10 10 0 0
GCK 47 22 52 28 / 10 10 0 0
EHA 49 25 54 31 / 10 0 0 0
LBL 50 22 54 29 / 10 10 0 0
HYS 42 24 52 28 / 10 10 0 0
P28 51 29 57 30 / 10 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...GERARD
SHORT TERM...GERARD
LONG TERM...RUSSELL
AVIATION...GERARD
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
856 AM EST SUN DEC 16 2012
.SYNOPSIS...
LOW PRESSURE DRIFTING EASTWARD ACROSS THE GREAT LAKES WILL PROVIDE
THE UPPER OHIO VALLEY WITH MILD CLOUDY CONDITIONS AND ISOLATED
LIGHT SHOWERS INTO MONDAY MORNING. THEN LOW PRESSURE FORMING NEAR
ARKANSAS TONIGHT WILL MOVE NORTHEASTWARD WITH MORE NUMEROUS
SHOWERS LATER MONDAY INTO EARLY TUESDAY. A STRONG COLD FRONT LATE
THURSDAY WILL BRING NOTICEABLY COLDER TEMPERATURES FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH MONDAY/...
BLEND OF RECENT SURFACE SATELLITE AND RADAR DATA COUPLED WITH
RECENT RAP WRF-NMM AND SREF MODEL OUTPUT SHOW CLOUDY MILD
CONDITIONS CONTINUING ACROSS THE UPPER OHIO VALLEY WITH NO MORE
THAN ISOLATED LIGHT SHOWERS THE REST OF TODAY AND TONIGHT.
SURFACE LAYER MOISTURE WILL BE INCREASING BUT LIFTING MECHANISMS
WILL REMAIN WEAK IN THE SOUTHERLY FLOW FEEDING THE LOW PRESSURE
CENTER DRIFTING EASTWARD ACROSS THE GREAT LAKES.
HOWEVER SREF AND NAM MODEL OUTPUT SHOW THAT WITH LOW PRESSURE
FORMING NEAR ARKANSAS TONIGHT...AND THEN MOVING NORTHEASTWARD
TOWARD THE UPPER OHIO VALLEY MONDAY...SHOWERS WILL BECOME MORE
NUMEROUS SOUTH TO NORTH ACROSS THE UPPER OHIO VALLEY MONDAY
AFTERNOON.
FORECASTED TEMPERATURES TO REMAIN MILD WITH VALUES ABOUT 20
DEGREES WARMER THAN NORMAL.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
RECENT SREF MODEL OUTPUT SHOWS SHOWERS ACROSS THE UPPER OHIO
VALLEY MONDAY NIGHT INTO TUESDAY AS LOW PRESSURE CENTER TRACKS NORTHEASTWARD
ALONG THE APPALACHIAN MOUNTAINS...EXITING PAST NEW ENGLAND TUESDAY
AFTERNOON.
ENSUING COLD POOL IS NOT THAT COLD OR DEEP...SO INSTABILITY
FOR SHOWERS WILL LIKEWISE BE WEAK. SO IT APPEARS LIKELY SHOWERS
WILL HAVE ENDED FOR MOST LOCATIONS BEFORE ANY CHANGE TO SNOW
OCCURS.
TEMPERATURES WILL NOT BE AS WARM...BUT STILL BE GENERALLY MORE
THAN 10 DEGREES WARMER THAN NORMAL.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
HIGH PRES RIDGING WL BUILD IN WED...WITH WAA KICKING IN AS THE
RIDGE AXIS PASSES EAST. MODELS WERE TRENDING MUCH WARMER WED AND
WED NT THAN EARLIER...SO INCREASED TEMPS DURING DURING THAT TIME.
NO OTHER MAJOR CHANGES TO THE LONG TERM PERIOD WERE MADE.
PREVIOUS...
THE NEXT STORM SYSTEM WILL DEVELOP IN THE PLAINS AND
BEGIN TO AFFECT THE REGION THURSDAY. WITH GOOD AGREEMENT FROM 12Z
GFS/ECMWF AND 00Z NAEFS...HAVE BUMPED UP POPS TO LIKELY THURSDAY
AFTERNOON AND EVENING AS BULK OF PRECIPITATION WILL COME THROUGH
WITH COLD FRONT.
LOW CENTER WILL THEN MEANDER ACROSS THE EASTERN GREAT LAKES ON
FRIDAY. THE LOW WILL PUMP COLD AIR INTO THE AREA ON FRIDAY...AND
TEMPERATURES MAY DECREASE THROUGHOUT THE ENTIRE DAY. COLD AIR AND
ADDITIONAL MOISTURE WILL ALLOW FOR A GOOD CHANCE OF LAKE
EFFECT/UPSLOPE SNOW SHOWERS FRIDAY AND SATURDAY.
ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY WILL TUMBLE
BELOW NORMAL FOR FRIDAY AND SATURDAY BEHIND THE COLD FRONT.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
RECENT SURFACE AND SATELLITE DATA SHOW STRATOCUMULUS CEILINGS
ACROSS THE UPPER OHIO VALLEY WILL VARY BETWEEN MVFR AND VFR INTO
TONIGHT. ANY SHOWERS WILL BE ISOLATED IN COVERAGE AND LIGHT IN
INTENSITY AND SHOULD NOT ADD TO ANY RESTRICTIONS.
SURFACE WINDS WILL BE FROM THE SOUTH AND SOUTHEAST AT 5 TO 10 KTS
INTO TONIGHT.
.OUTLOOK.../MONDAY THROUGH THURSDAY/...
IFR RESTRICTIONS CAN OCCUR LATE MONDAY INTO TUESDAY DUE TO SHOWERS
WITH NORTHEASTWARD PASSAGE OF LOW PRESSURE CENTER. SOME MVFR RESTRICTIONS
MAY REMAIN TUESDAY NIGHT INTO WEDNESDAY NIGHT WITH SOME PARTIAL
CLEARING. ANOTHER LOW PRESSURE SYSTEM WILL BRING RAIN/SNOW SHOWERS
AND RESTRICTIONS THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
629 AM EST SUN DEC 16 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 521 AM EST SUN DEC 16 2012
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW ACROSS
NAMERICA WITH NRN BRANCH FLOW CONFINED TO CANADA. ACTIVE SRN BRANCH
FLOW OVER THE CONUS FEATURES A TROF OVER THE ROCKIES UPSTREAM OF A
RDG ALONG THE E COAST. SHRTWV EMBEDDED IN THE WSW FLOW ALF BTWN
THESE LARGER SCALE FEATURES IS RIPPLING THRU THE GREAT LKS BUT
WEAKENING AS IT MOVES INTO THE LARGER SCALE UPR RDG. THIS
DISTURBANCE WAS RESPONSIBLE FOR THE RA/SN MIX THAT IMPACTED UPR MI
ON SAT...BUT LATEST IR IMAGERY INDICATES CLOUD TOP TEMPS ARE WARMING
OVER THE AREA UNDER LARGER SCALE H85-5 QVECTOR DVGC LEFT IN THE WAKE
OF THIS WEAKENING SHRTWV DESPITE DEEP MSTR SHOWN ON THE LOCAL 00Z
RAOBS. LINGERNIG PCPN IS ON THE LIGHT SIDE AND CONSISTS OF MAINLY
SCT -SHSNRA OVER THE E HALF OF THE CWA CLOSER TO THE DEPARTING
SHRTWV. SFC TEMPS REMAIN WELL ABV NORMAL...MAINLY 34 TO 39 AT 09Z.
SOME FOG HAS FORMED AS WELL UNDER THE UPR SUBSIDENCE/DRYING. JUST TO
THE W THERE IS ANOTHER AREA OF COLDER CLOUD TOPS OVER MN ASSOCIATED
WITH ANOTHER WEAKER SHRTWV NEAR MPX AND A NRN BRANCH DISTURBANCE
NEAR LK WINNIPEG. UNDER THE BAND OF HIER RADAR REFLECTIVIES...MANY
LOCATIONS OVER THE E HALF OF MN ARE REPORTING SOME -SN...MIXED WITH
-RA AT A FEW SPOTS.
FCST CONCERNS IN THE SHORT TERM REVOLVE ARND LINGERING PCPN
CHCS/PTYPE ASSOCIATED WITH DEPARTING DISTURBANCE AND THEN ON TIMING/
PTYPE OF POPS ASSOCIATED WITH PAIR OF SHRTWVS TO THE W.
TODAY...EXPECT LINGERING PCPN OVER MAINLY THE E HALF ASSOCIATED WITH
FIRST SHRTWV TO FADE THIS MRNG AND PERHAPS GIVE WAY TO SOME
-DZ/-FZDZ IN UPSLOPE AREAS IMPACTED BY LLVL SE FLOW AS THE
DISTURBANCE/ACCOMPANYING FORCING SHIFTS TO THE E AND DEEP QVECTOR
DVGC/SUBSIDENCE/UPR DRYING TAKES HOLD. BUT STRIPE OF PCPN TO THE W
WL BEGIN TO SHIFT E INTO THE WRN CWA BY 12Z AS THE PAIR OF SHRTWVS/
ACCOMPANYING H7-3 QVECTOR CNVGC MOVE TO THE E. HOWEVER...MODELS SHOW
THE QVECTOR CNVGC WEAKENING WITH TIME...PROBABLY BECAUSE OF
INCREASING CAD IN THE WAKE OF H85 LO SHIFTING THRU THE UPR LKS. SO
SUSPECT PCPN AMOUNTS ASSOCIATED WITH THE INCOMING BAND OF SN MIXED
WITH RA WL BE GREATEST OVER THE W BUT STILL ON THE LIGHT SIDE.
TONIGHT...LINGERING PCPN WL TRANSITION TO LES AS PAIR OF SHRTWVS TO
THE W FADE AND THE WNW FLOW IN THE WAKE OF H85 LO MOVING NE THRU
ONTARIO ADVECTS COLDER AIR INTO THE UPR LKS UNDER MID LVL DRYING.
HOWEVER...FCST H85 TEMPS FCST NO LOWER THAN -8 TO -9C /COMPARED TO
WATER TEMPS IN THE 4-5C RANGE/ AS WELL AS PLACEMENT OF THE DGZ ABV
THE LLVL MSTR SUGGEST THIS LES SHOULD BE RELATIVELY LIGHT.
MAINTAINED THE HIER LIKELY POPS OVER THE NW CWA WITH MORE FVRBL LLVL
CNVGC/UPSLOPE WIND COMPONENT/GREATER THERMAL INSTABILITY. BUT EVEN
THERE...ANY SN ACCUM SHOULD BE AOB 2 INCHES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 521 AM EST SUN DEC 16 2012
MONDAY...THE WEAK SFC LOW PRES WILL ONLY SLOWLY LIFT TO THE
NORTHEAST OF THE AREA AS THE MID/UPPER LEVEL TROUGH FROM NW ONTARIO
AND MANITOBA INTO THE NRN GREAT LAKES PERSISTS. WITH LITTLE OR NO
LARGE SCALE FORCING OVER THE AREA AND 850 MB TEMPS ONLY TO AROUND
-8C...LAKE INDUCED CAPE/INSTABILITY FOR ANY LES WILL ONLY BE
MARGINAL. THERE WILL STILL BE ENOUGH 850-750 MB MOISTURE OVER THE
AREA (INVERSION HEIGHTS NEAR 7K FT) FOR SCT/NMRS -SHSN EARLY MONDAY
INTO THE KEWEENAW AND FOR AREAS FROM MUNSING EASTWARD. HOWEVER...ONLY
LIGHT SNOWFALL AMOUNT OF AN INCH OR LESS ARE EXPECTED.
MONDAY NIGHT INTO TUE...WITH WINDS BACKING TO THE WEST AND BECOMING
LIGHT/ANTICYLONIC ALONG WITH FALLING INVERSION HEIGHTS AS A WEAK
RIDGE BUILD INTO THE AREA...ANY LINGERING LES WILL DIMINISH AND END
MON NIGHT WITH LITTLE OR NO ADDITIONAL ACCUMULATION. ONLY WEAK
FORCING WITH A SHORTWAVE TROUGH BRUSHING THE LATE MON NIGHT INTO TUE
WILL NOT BE ENOUGH TO SUPPORT ANY ADDITIONAL PCPN. A SHRTWV AND
ASSOCIATED BAND OF 285K-290K ISENTROPIC LIFT MOVING OUT OF THE
PLAINS INTO WI LATE TUE INTO TUE NIGHT COULD BRING SOME PATCHY LIGHT
SNOW INTO WEST UPPER MI.
WED-SAT...MODELS CONTINUE TO ADVERTISE POTENTIAL FOR A MAJOR WINTER
STORM SYSTEM MOVING OUT OF THE SOUTHERN PLAINS INTO THE CENTRAL
GREAT LAKES. THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE
TRACK OF THE SYSTEM WITH CONSENSUS BRINGING THE SFC LOW THROUGH LOWER
MI. HOWEVER...SIGNFICANT UNCERTAINTY REMAINS WITH THE EVENTUAL TRACK
AND STRENGTH AT THIS TIME FRAME. THE MAIN CLUSTER OF SOLUTIONS FROM THE
GFS ENSEMBLES AND OPERATIONAL GFS/ECMWF/UKMET WOULD BRING THE SYSTEM
CLOSE ENOUGH TO UPPER MI FOR SIGNFICANT SYNOPTIC SNOW ACROSS THE EAST
HALF OF THE CWA THU INTO THU NIGHT. UNLESS THE STORM AND DEEPER
MOISTURE MOVE TOO FAR TO THE SOUTH...A SIGNFICANT LAKE ENHANCED SNOW
TRANSITIONING TO PURE LES WOULD ALSO BE LIKELY FOR NORTH WIND FAVORED
SNOWBELTS INTO FRI. WITH A DEEP LOW PRES SYSTEM LIKELY...THERE WILL
BE THE POTENTIAL FOR VERY DIFFICULT TRAVEL CONDITIONS WITH SN/BLSN.
ADDITIONAL LES FOR N TO NW SNOWBELTS IS ALSO POSSIBLE INTO SATURDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 628 AM EST SUN DEC 16 2012
EXPECT IFR/LIFR CONDITIONS TO PREDOMINATE THRU TODAY AT ALL 3 SITES
WITH LINGERING LLVL MSTR ACCOMPANYING PASSAGE OF SFC LO PRES TROF.
SOME VLIFR CONDITIONS ARE LIKELY EARLY AT CMX AS WELL. CONDITIONS
ARE LIKELY TO IMPROVE TO MVFR TNGT AT IWD/SAW WITH W FLOW IN THE
WAKE OF THE TROF PASSAGE BRINGING A BIT DRIER LLVL AIR AS WELL A
DOWNSLOPE WIND COMPONENT TO SAW. IFR CONDITIONS ARE LIKELY TO
PERSIST THE ENTIRE PERIOD AT CMX WITH UPSLOPE WIND ALSO MOISTENED BY
PASSAGE OVER LK SUP.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 521 AM EST SUN DEC 16 2012
AS A LO PRES TROF SHIFTS E ACROSS THE LAKE TODAY...EXPECT
DIMINISHING SE WINDS OVER THE E. ALLOWED GOING GALE WARNING FOR THE
FAR E TO EXPIRE AT 09Z AS SCHEDULED. FOLLOWING THE TROF PASSAGE THRU
TONIGHT...PLAN ON A WIND SHIFT TO THE WNW W TO E. BUT A FAIRLY WEAK
PRES GRADIENT THRU TONIGHT SHOULD KEEP THESE WINDS NO HIER THAN
15-25 KTS.
NORTH GALES ARE POSSIBLE LATE THURSDAY INTO FRIDAY AS A DEEPENING LOW
PRESSURE SYSTEM MOVES FROM THE MID MISSISSIPPI VALLEY INTO THE
CENTRAL GREAT LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLB
AVIATION...KC
MARINE...KC/JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
527 AM EST SUN DEC 16 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 521 AM EST SUN DEC 16 2012
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW ACROSS
NAMERICA WITH NRN BRANCH FLOW CONFINED TO CANADA. ACTIVE SRN BRANCH
FLOW OVER THE CONUS FEATURES A TROF OVER THE ROCKIES UPSTREAM OF A
RDG ALONG THE E COAST. SHRTWV EMBEDDED IN THE WSW FLOW ALF BTWN
THESE LARGER SCALE FEATURES IS RIPPLING THRU THE GREAT LKS BUT
WEAKENING AS IT MOVES INTO THE LARGER SCALE UPR RDG. THIS
DISTURBANCE WAS RESPONSIBLE FOR THE RA/SN MIX THAT IMPACTED UPR MI
ON SAT...BUT LATEST IR IMAGERY INDICATES CLOUD TOP TEMPS ARE WARMING
OVER THE AREA UNDER LARGER SCALE H85-5 QVECTOR DVGC LEFT IN THE WAKE
OF THIS WEAKENING SHRTWV DESPITE DEEP MSTR SHOWN ON THE LOCAL 00Z
RAOBS. LINGERNIG PCPN IS ON THE LIGHT SIDE AND CONSISTS OF MAINLY
SCT -SHSNRA OVER THE E HALF OF THE CWA CLOSER TO THE DEPARTING
SHRTWV. SFC TEMPS REMAIN WELL ABV NORMAL...MAINLY 34 TO 39 AT 09Z.
SOME FOG HAS FORMED AS WELL UNDER THE UPR SUBSIDENCE/DRYING. JUST TO
THE W THERE IS ANOTHER AREA OF COLDER CLOUD TOPS OVER MN ASSOCIATED
WITH ANOTHER WEAKER SHRTWV NEAR MPX AND A NRN BRANCH DISTURBANCE
NEAR LK WINNIPEG. UNDER THE BAND OF HIER RADAR REFLECTIVIES...MANY
LOCATIONS OVER THE E HALF OF MN ARE REPORTING SOME -SN...MIXED WITH
-RA AT A FEW SPOTS.
FCST CONCERNS IN THE SHORT TERM REVOLVE ARND LINGERING PCPN
CHCS/PTYPE ASSOCIATED WITH DEPARTING DISTURBANCE AND THEN ON TIMING/
PTYPE OF POPS ASSOCIATED WITH PAIR OF SHRTWVS TO THE W.
TODAY...EXPECT LINGERING PCPN OVER MAINLY THE E HALF ASSOCIATED WITH
FIRST SHRTWV TO FADE THIS MRNG AND PERHAPS GIVE WAY TO SOME
-DZ/-FZDZ IN UPSLOPE AREAS IMPACTED BY LLVL SE FLOW AS THE
DISTURBANCE/ACCOMPANYING FORCING SHIFTS TO THE E AND DEEP QVECTOR
DVGC/SUBSIDENCE/UPR DRYING TAKES HOLD. BUT STRIPE OF PCPN TO THE W
WL BEGIN TO SHIFT E INTO THE WRN CWA BY 12Z AS THE PAIR OF SHRTWVS/
ACCOMPANYING H7-3 QVECTOR CNVGC MOVE TO THE E. HOWEVER...MODELS SHOW
THE QVECTOR CNVGC WEAKENING WITH TIME...PROBABLY BECAUSE OF
INCREASING CAD IN THE WAKE OF H85 LO SHIFTING THRU THE UPR LKS. SO
SUSPECT PCPN AMOUNTS ASSOCIATED WITH THE INCOMING BAND OF SN MIXED
WITH RA WL BE GREATEST OVER THE W BUT STILL ON THE LIGHT SIDE.
TONIGHT...LINGERING PCPN WL TRANSITION TO LES AS PAIR OF SHRTWVS TO
THE W FADE AND THE WNW FLOW IN THE WAKE OF H85 LO MOVING NE THRU
ONTARIO ADVECTS COLDER AIR INTO THE UPR LKS UNDER MID LVL DRYING.
HOWEVER...FCST H85 TEMPS FCST NO LOWER THAN -8 TO -9C /COMPARED TO
WATER TEMPS IN THE 4-5C RANGE/ AS WELL AS PLACEMENT OF THE DGZ ABV
THE LLVL MSTR SUGGEST THIS LES SHOULD BE RELATIVELY LIGHT.
MAINTAINED THE HIER LIKELY POPS OVER THE NW CWA WITH MORE FVRBL LLVL
CNVGC/UPSLOPE WIND COMPONENT/GREATER THERMAL INSTABILITY. BUT EVEN
THERE...ANY SN ACCUM SHOULD BE AOB 2 INCHES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 521 AM EST SUN DEC 16 2012
MONDAY...THE WEAK SFC LOW PRES WILL ONLY SLOWLY LIFT TO THE
NORTHEAST OF THE AREA AS THE MID/UPPER LEVEL TROUGH FROM NW ONTARIO
AND MANITOBA INTO THE NRN GREAT LAKES PERSISTS. WITH LITTLE OR NO
LARGE SCALE FORCING OVER THE AREA AND 850 MB TEMPS ONLY TO AROUND
-8C...LAKE INDUCED CAPE/INSTABILITY FOR ANY LES WILL ONLY BE
MARGINAL. THERE WILL STILL BE ENOUGH 850-750 MB MOISTURE OVER THE
AREA (INVERSION HEIGHTS NEAR 7K FT) FOR SCT/NMRS -SHSN EARLY MONDAY
INTO THE KEWEENAW AND FOR AREAS FROM MUNSING EASTWARD. HOWEVER...ONLY
LIGHT SNOWFALL AMOUNT OF AN INCH OR LESS ARE EXPECTED.
MONDAY NIGHT INTO TUE...WITH WINDS BACKING TO THE WEST AND BECOMING
LIGHT/ANTICYLONIC ALONG WITH FALLING INVERSION HEIGHTS AS A WEAK
RIDGE BUILD INTO THE AREA...ANY LINGERING LES WILL DIMINISH AND END
MON NIGHT WITH LITTLE OR NO ADDITIONAL ACCUMULATION. ONLY WEAK
FORCING WITH A SHORTWAVE TROUGH BRUSHING THE LATE MON NIGHT INTO TUE
WILL NOT BE ENOUGH TO SUPPORT ANY ADDITIONAL PCPN. A SHRTWV AND
ASSOCIATED BAND OF 285K-290K ISENTROPIC LIFT MOVING OUT OF THE
PLAINS INTO WI LATE TUE INTO TUE NIGHT COULD BRING SOME PATCHY LIGHT
SNOW INTO WEST UPPER MI.
WED-SAT...MODELS CONTINUE TO ADVERTISE POTENTIAL FOR A MAJOR WINTER
STORM SYSTEM MOVING OUT OF THE SOUTHERN PLAINS INTO THE CENTRAL
GREAT LAKES. THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE
TRACK OF THE SYSTEM WITH CONSENSUS BRINGING THE SFC LOW THROUGH LOWER
MI. HOWEVER...SIGNFICANT UNCERTAINTY REMAINS WITH THE EVENTUAL TRACK
AND STRENGTH AT THIS TIME FRAME. THE MAIN CLUSTER OF SOLUTIONS FROM THE
GFS ENSEMBLES AND OPERATIONAL GFS/ECMWF/UKMET WOULD BRING THE SYSTEM
CLOSE ENOUGH TO UPPER MI FOR SIGNFICANT SYNOPTIC SNOW ACROSS THE EAST
HALF OF THE CWA THU INTO THU NIGHT. UNLESS THE STORM AND DEEPER
MOISTURE MOVE TOO FAR TO THE SOUTH...A SIGNFICANT LAKE ENHANCED SNOW
TRANSITIONING TO PURE LES WOULD ALSO BE LIKELY FOR NORTH WIND FAVORED
SNOWBELTS INTO FRI. WITH A DEEP LOW PRES SYSTEM LIKELY...THERE WILL
BE THE POTENTIAL FOR VERY DIFFICULT TRAVEL CONDITIONS WITH SN/BLSN.
ADDITIONAL LES FOR N TO NW SNOWBELTS IS ALSO POSSIBLE INTO SATURDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 730 PM EST SAT DEC 15 2012
IFR/LIFR CONDITIONS WL PREDOMINATE THIS FCST PERIOD AS LOW-LVL
MOISTURE PERSISTS FROM THE ARRIVAL OF A LOW PRESSURE SYSTEM MOVING
THROUGH THE GREAT LAKES. VLIFR CONDITIONS ARE EXPECTED LATE TONIGHT
INTO SUNDAY MORNING...ESPECIALLY AT KCMX AND POSSIBLY KSAW IN
PREVAILING LIGHT E-SE UPSLOPE FLOW AND DRYING CONDITIONS ALOFT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 521 AM EST SUN DEC 16 2012
AS A LO PRES TROF SHIFTS E ACROSS THE LAKE TODAY...EXPECT
DIMINISHING SE WINDS OVER THE E. ALLOWED GOING GALE WARNING FOR THE
FAR E TO EXPIRE AT 09Z AS SCHEDULED. FOLLOWING THE TROF PASSAGE THRU
TONIGHT...PLAN ON A WIND SHIFT TO THE WNW W TO E. BUT A FAIRLY WEAK
PRES GRADIENT THRU TONIGHT SHOULD KEEP THESE WINDS NO HIER THAN
15-25 KTS.
NORTH GALES ARE POSSIBLE LATE THURSDAY INTO FRIDAY AS A DEEPENING LOW
PRESSURE SYSTEM MOVES FROM THE MID MISSISSIPPI VALLEY INTO THE
CENTRAL GREAT LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLB
AVIATION...VOSS
MARINE...KC
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
514 AM CST SUN DEC 16 2012
.UPDATE...FOR 12Z AVIATION DISCUSSION BELOW
&&
.DISCUSSION.../ISSUED 235 AM CST SUN DEC 16 2012/
THERE ARE A FEW MINOR WEATHER ISSUES WITH
WHICH TO CONTEND OVER THE UPCOMING WEEK... BUT THE BIG STORY WILL
LIKELY BE A STRONG WINTER STORM OVER THE CENTRAL AND EASTERN CONUS
THE SECOND HALF OF THE WEEK. WE LOOK TO MISS OUT ON THAT SYSTEM
UNLESS THINGS CHANGE DRAMATICALLY... BUT WITH MODELS CONTINUING TO
TREND EAST IT APPEARS ONLY THE EASTERN PORTION OF THE AREA WILL
HAVE ANY CHANCE OF SEEING SNOWFALL... AND EVEN THOSE LOCATIONS
COULD SEE LITTLE OR NOTHING. IN THE BIG PICTURE... THE AMPLIFIED
UPPER LEVEL PATTERN LOOKS TO REMAIN IN PLACE THROUGH THE WEEK...
WITH TROUGHING OVER OUR AREA THROUGH MIDWEEK GIVING WAY TO UPPER
RIDGING BY WEEK/S END AS UPPER TROUGHS SETUP AS BOOKENDS ALONG THE
WEST AND EAST COASTS.
IN THE SHORT TERM... PCPN CURRENTLY OVER THE EASTERN PORTION OF
THE AREA WILL CONTINUE TO MOVE EAST THIS MORNING AS THE SURFACE
LOW OVER WISCONSIN MOVES INTO UPPER MICHIGAN BY THIS EVENING.
HOWEVER... THERE WILL BE ENOUGH LINGERING MOISTURE AND CYCLONIC
FLOW... AS WELL AS A WEAK SHORTWAVE MOVING THROUGH... TO KEEP SOME
LIGHT PCPN GOING THROUGH AT LEAST THE MORNING HOURS. COLDER
TEMPERATURES CONTINUE TO WORK INTO THE AREA... SO THE EXPECTATION
IS THAT ANY REMAINING PCPN SHOULD BE IN THE FORM OF SNOW BY 12Z.
HOWEVER... SHOULD THE DEEPER MOISTURE EXIT TOO QUICKLY THERE COULD
BE SOME PATCHY DRIZZLE OR FREEZING DRIZZLE... SO THAT WILL NEED TO
BE MONITORED. KEPT SOME LOW POPS OVER THE FAR EAST INTO THIS
AFTERNOON... ALTHOUGH ANYTHING THAT REMAINS SHOULD BE PATCHY AND
VERY LIGHT. A WEAK SURFACE RIDGE WILL WORK ACROSS THE AREA TONIGHT
THROUGH MONDAY... BUT IT PROBABLY WON/T DO MUCH TO SCOUR OUT CLOUD
COVER BASED ON THE NAM AND GFS 925-850MB MOISTURE PROFILES AS WELL
AS CURRENT UPSTREAM OBSERVATIONS AND 11-3.9 MICRON SATELLITE
IMAGERY. SO... KEPT MOSTLY CLOUDY CONDITIONS IN PLACE THROUGH
MONDAY WITH A DRY FORECAST. SOME WEAK ISENTROPIC LIFT AND
850-700MB FRONTOGENESIS WILL LIFT ACROSS THE AREA ON TUESDAY AS A
WEAK SURFACE LOW MOVES THROUGH THE REGION. THE BEST COMBINATION OF
FORCING AND DEEP LAYER SATURATION LOOKS TO OCCUR TO OUR NORTH...
BUT WE STILL LOOK TO HAVE ENOUGH COMING TOGETHER FOR AT LEAST
CHANCE POPS AT THIS POINT. COULD EVENTUALLY SEE SOME LIGHT
ACCUMULATIONS DEPENDING ON WHERE THE AXIS OF PCPN SETS UP... BUT
BY NO MEANS DOES IT APPEAR TO BE A SIGNIFICANT ISSUE AT THIS POINT.
SHORTWAVE RIDGING WILL OCCUR ACROSS OUR AREA TUESDAY NIGHT INTO
WEDNESDAY AHEAD OF THE MAJOR SYSTEM THAT WILL AFFECT LOCATIONS
MAINLY SOUTH/EAST OF US. THAT SYSTEM LOOKS TO GET ORGANIZED IN THE
LEE OF THE SOUTHERN ROCKIES WEDNESDAY MORNING... THEN LIFT
NORTHEAST ACROSS MISSOURI AND ILLINOIS WEDNESDAY NIGHT AND INTO
LOWER MICHIGAN BY THURSDAY AFTERNOON. THE EASTERN HALF OF THE CWFA
COULD GET CLIPPED BY SOME OF THE PCPN... ALTHOUGH THE ECMWF...
GFS... AND FIM CONTINUE TO SUGGEST ALL BUT THE FAR EASTERN PORTION
OF THE AREA WILL ENTIRELY MISS OUT ON PCPN. FOR NOW... KNOCKED
DOWN POPS FROM WHAT CONSENSUS GUIDANCE SUGGESTED... BUT KEPT SOME
CHANCE POPS FOR ROUGHLY THE SOUTHEAST HALF OF THE FORECAST AREA.
HOWEVER... IF TRENDS CONTINUE THEN LATER FORECASTS SHOULD BE ABLE
TO LOWER POPS FURTHER AND PERHAPS ONLY KEEP A MENTION FOR THE
EASTERN TIER OR TWO OF COUNTIES. GOOD UPPER RIDGING LOOKS TO WORK
INTO THE AREA BEHIND THE SYSTEM... WITH DRY WEATHER ACROSS THE
ENTIRE AREA FOR THE END OF THE WEEK.
&&
.AVIATION.../12Z TAF ISSUANCE/
EXPECT IFR CIGS TO PREVAIL AT THE TAF SITES TODAY. A SLIVER OF
CLEAR SKIES DEVELOPED OVERNIGHT OVER WEST CENTRAL AND SOUTHWEST
MN...EBUT XPECT STRATUS TO FILL BACK IN PER 16.09Z RAP 925MB RH
PROGS. VSBYS WILL TINKER BETWEEN LOW-END VFR AND HIGH-END
MVFR...BUT SHOULD IMPROVE TO AROUND 4SM OR BETTER THIS MORNING
WITH THE EXIT OF THE TROUGH AND PRECIP. GRADUAL IMPROVEMENT IS
EXPECTED FROM WESTERN TOWARD CENTRAL MN BY THIS EVENING...BUT MOST
SITES SHOULD NOT IMPROVE TO VFR UNTIL BETWEEN 06Z AND 12Z
MONDAY...WITH THE EXCEPTION OF KRWF. PREVALENT NORTHWEST WINDS
THROUGH THE PERIOD...WITH SPEEDS AROUND 10 KTS DECREASE TO BELOW 5
KTS SUNDAY EVE.
KMSP...IFR CIGS EXPECTED THROUGH THIS MORNING...IMPROVING TO MVFR
LATE THIS EVENING. CONFIDENCE ON IMPROVEMENT TO MVFR IS RATHER
LOW. ALSO EXPECT SOME MIST THIS MORNING WITH VSBYS AROUND
6SM...BUT SHOULD SEE AN UNRESTRICTED VSBY BY THIS AFTERNOON.
NORTHWEST WINDS OF 7 TO 10 KTS TODAY DECREASE BELOW 5 KTS BY 06Z MONDAY.
/OUTLOOK FOR KMSP/
MON...VFR WITH MVFR CIGS POSSIBLE. WINDS NW AT 5KTS.
TUE...MVFR WITH -SN POSSIBLE. WINDS SE BECOMING W AT 5KTS LATE.
WED...VFR. WINDS WNW AT 5-10KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
TRH/LS
AREA FORECAST DISCUSSION
NWS JACKSON MS
406 AM CST SUN DEC 16 2012
...HEAVY RAIN/FEW SEVERE STORMS POSSIBLE TODAY INTO TONIGHT...
.SHORT TERM...(TODAY THROUGH MONDAY NIGHT)...
MAIN CONVECTIVE BAND ACROSS N MS INTO SRN AR STEADILY EXPANDING/
GETTING STRONGER PAST SEVERAL HOURS. OTHERWISE...ISOLATED LIGHT SHRA
CONTINUE TO CROSS N AND W PORTIONS OF THE CWFA WITH LOW STRATUS
ELSEWHERE. STALLED FRONTAL BOUNDARY STILL HANGING BACK NEAR A KJBR-
KTYR LINE AS AN UPSTREAM S/WV OVER THE SRN ROCKIES TO THE TX BIG BEND
MOVES EWD AT 40KTS TOWARD THE OZARKS. A POWERFUL UPPER JET WITH EPAC
CONNECTIONS WILL AID IN RAINFALL PRODUCTION GETTING RAMPED UP TODAY
WITH CONTINUED EXPANSION OF THE PRE-FRONTAL CONVECTION. LIKELY
TRAINING OF CONVECTION IN THIS SCENARIO DURING THE DAYLIGHT HOURS
COULD GENERATE AN AXIS OF 2-4 INCHES RATHER EASILY. MODEL CONSENSUS
PLACES THE HEAVIEST RAINFALL FROM AROUND NATCHEZ TO MERIDIAN BETWEEN
NOON AND MIDNIGHT...SOME RISK FOR LOCALIZED FLASH FLOODING WILL EXIST
BUT WILL HOLD OFF A FLASH FLOOD WATCH UNTIL THE AXIS BECOMES MORE
DEFINED SINCE 3HR FFG STILL ABOVE 3 INCHES MOST AREAS.
UNTIL THE DIURNAL INSTABILITY GETS ADDED TO THE MIX...LOOK FOR THE
EXPANDING RAIN BAND TO PUSH TO NEAR A WINNSBORO TO JACKSON TO
COLUMBUS AXIS BY ABOUT NOON...PER LATEST RUC PROGS. THEN THE RISK
FOR A FEW STRONG/SEVERE STORMS WILL BE INCREASING S OF THAT AXIS
THROUGH THE EVENING HOURS FUELED BY PWATS RISING NEAR 1.5 INCHES...
0-3KM HELICITIES OF 200-300M*M/S*S...6.5C 7-500MB LAPSE RATES...
INCREASINGLY COUPLED 850-200MB DIFFERENTIAL DIVERGENCE...850MB THETA
E AXIS OF 334K AND LEFT EXIT REGION OF A 65KT 500MB JET STREAK.
AT THIS POINT IT LOOKS LIKE THE AREA WITH THE GREATEST SEVERE
WEATHER RISK WILL BE ACROSS THE SERN HALF OF THE CWA WHERE THE BEST
COMBINATION OF SHEAR AND INSTABILITY WILL BE CO-LOCATED. EVEN A
DECENT TORNADO RISK COULD DEVELOP FOR SERN MS FROM 00-06Z AS A LAYER
OF MARINE GULF AIR OF 65-68F DEWPTS ATTEMPTS TO SURGE NWD...REF NEW
SPC DAY ONE OUTLOOK FOR UPDATES.
PRIMARY ASCENT PUSHES OFF TO OUR E MONDAY MORNING WITH DEVELOPING
UNIDIRECTIONAL FLOW FROM THE WSW BY MIDDAY. DRYING PWATS DROP TO
NEAR ONE HALF INCH BY MIDDAY ACROSS I-55...AND CLOSER TO ONE THIRD
INCH BY MIDNIGHT MONDAY NIGHT WHEN BEST CLEARING EXPECTED OF THE
REMAINING CLOUD COVER. DUE TO THE BEST RAINFALL AXIS POSITION LYING
ALONG OR S OF I-20 DURING SUNDAY...HAVE ADDED PATCHY FOG TO SRN HALF
OF CWFA LATE MONDAY NIGHT WHERE WET GROUNDS AND COOLER L40S TEMPS
EXIST UNDER NEAR CALM SURFACE WIND/CLEAR SKY CONDITIONS.
AS FOR TEMPS/POPS...RAISED GFS MOS POPS TODAY FOR NWRN HALF BEFORE
NOON AND THE SERN HALF DURING THE AFTERNOON THROUGH OVERNIGHT
PERIODS. MOS TEMP RANGE SEEMED A BIT HIGH SO NARROWED THE HIGH/LOW
RANGE A BIT THROUGH MONDAY WHILE ACCEPTING GUIDANCE FOR MONDAY
NIGHT. /40/
.LONG TERM...(TUESDAY THROUGH SUNDAY)...
SURFACE HIGH PRESSURE WILL SHIFT OFF TO OUR EAST ON TUE BRINGING
BACK RETURN FLOW OFF THE GULF. UNSEASONABLY WARM CONDITIONS CAN BE
EXPECTED TUE AND WED AS A RESULT/ESPECIALLY WED WHERE HIGHS IN THE
LOW TO MID 70S WILL COME IN SOME 15 DEGREES ABOVE NORMAL FOR MID
DEC. THE WARMTH WILL NOT LAST LONG THOUGH AS A POTENT COLD FRONT IS
PROGGED TO CROSS THE REGION STARTING EARLY THU MORNING.
THE UPPER WAVE ASSOC WITH THIS NEXT SYSTEM WILL CROSS INTO THE
CENTRAL PLAINS WED EVENING INDUCING A DEEP SURFACE LOW OVER THE
OKLAHOMA PANHANDLE THAT WILL TRACK EAST NORTHEAST ACROSS SOUTHERN MO
AND EVENTUALLY THE GREAT LAKES. THE SYNOPTIC SETUP OFFERED BY THE
MODELS WITH THIS SYSTEM IS QUITE IMPRESSIVE...AND AT FIRST GLANCE IT
WOULD APPEAR THAT SEVERE WEATHER FOR THE ARKLAMISS WOULD BE A SLAM
DUNK. HOWEVER THE DETAILS OFFER A DIFFERENT STORY...AT LEAST FOR
NOW. WHILE ROBUST WIND FIELDS JUST AHEAD OF THE FRONT DRAW UP AMPLE
AMOUNTS OF MOISTURE/DEW POINTS CLIMBING NEAR OR ABOVE 65 DEG FOR A
GOOD PORTION OF THE AREA AND PW VALUES RISING ABOVE 1.5 IN/
TEMPERATURES ALOFT ARE RATHER WARM(H5 TEMPS -10 TO -11) WHICH
SIGNIFICANTLY REDUCES MID LEVEL LAPSE RATES AND RESULTANT
INSTABILITY. WE WILL HAVE TO KEEP AN EYE ON THIS TO SEE IF THE
MODELS TREND COOLER ALOFT BECAUSE IF THEY DO...AND THE SYNOPTIC
SETUP REMAINS SIMILAR...WE COULD BE LOOKING AT DECENT SEVERE WEATHER
POTENTIAL LATE WED INTO THU MORNING. FOR NOW...WILL OMIT MENTION OF
ANY SEVERE WEATHER IN THE HWO/GRAPHICS.
MUCH COOLER AIR WILL FILTER ACROSS THE REGION IN WAKE OF THE FRONT
WITH TEMPERATURES LIKELY FALLING THROUGH THE DAYLIGHT HOURS THU.
STRONG MIXING WILL ALLOW WINDY CONDITIONS TO DEVELOP THU AND ITS
FEASIBLE A WIND ADVISORY MAY BECOME NECESSARY FOR AT LEAST THE
DELTA...IF NOT AREAS FURTHER SOUTH AND EAST AS WELL. HIGH PRESSURE
WILL TRANSIT THE DEEP SOUTH FRI INTO THE FIRST PART OF THE WEEKEND
BEFORE RAIN CHANCES RETURN EARLY NEXT WEEK. /BK/
&&
.AVIATION...WIDESPREAD MVFR CEILINGS AT DAYBREAK SHOULD DETERIORATE
TO FREQUENTLY IFR CONDITIONS IN ADVANCING RAIN/TSRA BAND SAGGING SWD
THROUGH THE TAF SITES. SSWLY SFC WINDS WL BECOME A LITTLE GUSTY
AHEAD OF THE PRECIPITATION THRU THE AFTN BEFORE WEAKENING THIS
EVENING. SHRA AND TSRA ACTIVITY WILL BE STRONGEST/HEAVIEST ACROSS
THE I-20 CORRIDOR AND SWD BY THIS AFTERNOON WHILE IT ALL WILL
GRADUALLY END FROM NW TO SE LATER TONIGHT FOR THE DELTA REGION AND
DURING MONDAY MORNING FOR OUR ERN/SRN SITES. A GRADUAL SHIFT TO
WSWLY LOW LEVEL FLOW WILL RETURN VFR CONDITIONS AND WILL HELP THE
RAINS ON MONDAY WITH CLEARING SKIES MONDAY EVENING. /40/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 69 56 69 41 / 97 70 17 5
MERIDIAN 70 58 69 39 / 97 83 22 7
VICKSBURG 68 56 66 36 / 97 50 11 4
HATTIESBURG 73 61 72 42 / 80 91 31 6
NATCHEZ 69 57 68 40 / 98 69 11 4
GREENVILLE 69 53 65 40 / 92 27 9 4
GREENWOOD 68 53 65 42 / 97 44 11 5
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
40/BK
AREA FORECAST DISCUSSION
NWS HASTINGS NE
906 AM CST SUN DEC 16 2012
.UPDATE...MADE SOME CHANGES TO WEDNESDAY AND WEDNESDAY NIGHT
FORECAST. ADJUSTED THE GRADIENT FOR CHANCES OF PRECIPITATION ON
WEDNESDAY AND INCREASED CHANCES OF PRECIPITATION CENTRAL/SOUTH A
BIT. ALSO BROKE UP WEATHER AND CHANCES OF PRECIPITATION INTO 6
HOUR BLOCKS WEDNESDAY AND WEDNESDAY NIGHT...AS BOTH WEDNESDAY
MORNING AND LATE WEDNESDAY NIGHT APPEAR TO HAVE MUCH LOWER CHANCES
OF SNOW COMPARED TO WEDNESDAY AFTERNOON AND EVENING. ALSO ADJUSTED
SKY COVER TO BE COMPLETELY CLOUDY FOR WEDNESDAY AFTERNOON AND
EVENING.
&&
.PREV DISCUSSION... /ISSUED 514 AM CST SUN DEC 16 2012/
AVIATION...12Z KGRI TAF. VFR CONDITIONS EXPECTED THROUGH THE NEXT
24 HOURS. STRATUS IS NOTED ON SATELLITE IMAGERY...WITH SURFACE
OBSERVATIONS REPORTING VISIBILITY RESTRICTIONS IN FOG...FROM
EASTERN NEBRASKA INTO EASTERN AND CENTRAL KANSAS. THIS AREA OF
STRATUS AND FOG IS PIVOTING AROUND SOUTH CENTRAL NEBRASKA AND IS
NOT EXPECTED TO IMPACT THE TERMINAL. LOW TO MID LEVEL CLOUDS ARE
HOWEVER MOVING INTO THE TERMINAL FROM THE WEST/SOUTHWEST. THE
MAJORITY OF GUIDANCE SUGGESTS THE TERMINAL WILL REMAIN AT VFR
LEVELS WITH CEILINGS DROPPING NO LOWER THAN 4000 OR 3500 FT AGL.
THAT BEING SAID IT IS WORTH NOTING THAT ONE SET OF GUIDANCE DOES
SUGGEST MVFR CONDITIONS COULD BE REALIZED BY LATE MORNING. THERE
ARE SOME MVFR CEILINGS OVER SOUTHWESTERN NEBRASKA...BUT IT IS
CURRENTLY BELIEVED THAT A RELATIVELY DRY LOWER TROPOSPHERE WILL
PREVENT THESE CEILINGS FROM BEING REALIZED AT KGRI. GIVEN ALL
THIS...WENT AHEAD WITH CEILINGS NO LOWER THAN 3500FT AGL FOR KGRI.
THE SURFACE WIND WILL REMAIN LIGHT AND VARIABLE DURING THE TAF
PERIOD AND AS HINTED AT EARLIER...VISIBILITY RESTRICTIONS ARE NOT
EXPECTED THROUGH THE NEXT 24 HOURS.
PREV DISCUSSION... /ISSUED 433 AM CST SUN DEC 16 2012/
SHORT TERM...THROUGH 12Z WEDNESDAY. EVENING UPPER AIR ANALYSIS
INDICATES A LONGWAVE TROUGH OVER THE WESTERN HALF OF THE CONUS
WITH QUASI- ZONAL FLOW ACROSS THE EAST. MID AND UPPER LEVEL JET
ENERGY EXTENDS FROM WEST-TEXAS...EAST/NORTHEAST INTO THE SOUTHERN
PLAINS AND LOWER MISSISSIPPI VALLEY...AND THEN FARTHER EAST INTO
THE SOUTHEASTERN CONUS. MID AND UPPER LEVEL TROPOSPHERIC FLOW OVER
OUR AREA REMAINS FAIRLY WEAK AS A RESULT...MAXING OUT AT AROUND
60KTS NEAR 200MB PER 00Z SOUNDING DATA FROM KLBF. WATER VAPOR
IMAGERY SHOWS PLENTY OF MID LEVEL MOISTURE ADVANCING
EAST/NORTHEAST ALONG THE MID TO UPPER LEVEL JET AXIS ACROSS THE
SOUTH AND SOUTHEASTERN CONUS...WITH DRIER MID LEVEL AIR NOTED
FARTHER NORTH. WATER VAPOR IMAGERY ALSO INDICATES A COMPACT MID
LEVEL SHORT WAVE OVER COLORADO...BEGINNING TO EJECT OUT FROM THE
MAIN LONGWAVE TROUGH. AT THE SURFACE A RIDGE OF HIGH PRESSURE IS
NOTED EXTENDING FROM THE NORTHERN HIGH PLAINS...SOUTH/SOUTHEAST
INTO THE CENTRAL PLAINS. A COLD FRONT IS ALSO NOTED EXTENDING FROM
SOUTHWEST TO NORTHEAST ACROSS KANSAS...SOUTHWESTERN MISSOURI AND
IOWA. THE LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE
NORTHWEST AS A RESULT. RADAR DATA FROM KUEX...KLNX AND KGLD
CONTINUE TO SHOW PRECIPITATION OVER SOUTHWESTERN NEBRASKA AND
NORTHWESTERN KANSAS...WITH SNOW BEING REPORTED OVER SOME AREAS AS
WELL. FOR LOCATIONS ACROSS OUR WESTERN CWA...WHERE KUEX HAS
INDICATED PRECIPITATION FOR THE PAST FEW HOURS...PRECIPITATION AT
THE SURFACE HAS YET TO BE REPORTED AS THE LOWER TROPOSPHERE STILL
APPEARS TOO DRY FOR SUCH ACTIVITY TO BE REALIZED.
GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL
SUGGEST THE MID LEVEL SHORT WAVE...APPROACHING OUR AREA FROM
COLORADO...WILL CONTINUE PUSHING ACROSS THE CENTRAL PLAINS DURING
THE DAY TODAY. DPVA AND WEAK MID LEVEL THERMAL ADVECTION AHEAD OF
THE MID LEVEL TROUGH AXIS...WORKING IN CONCERT WITH AN AXIS OF
FRONTOGENESIS NEAR 700MB...SHOULD SUSTAIN PRECIPITATION PRODUCTION
OVER NORTHWESTERN KANSAS AND SOUTHWESTERN NEBRASKA THROUGH THE
NEXT FEW HOURS...WITH PRECIPITATION PERHAPS MAKING IT TO THE
SURFACE ACROSS WESTERN PORTIONS OF OUR AREA AS WELL. FORECAST
PROXIMITY SOUNDINGS FROM ACROSS MUCH OF OUR CWA...PER THE NAM AND
OPERATIONAL GFS...SUGGEST THE LOWER TROPOSPHERE WILL HAVE TO DO
QUITE A BIT OF SATURATING FARTHER EAST BEFORE PRECIPITATION IS
REALIZED AT THE SURFACE...THUS CONFIDENCE IS NOT ALL THAT HIGH
THAT ANY MEASURABLE PRECIPITATION WILL BE REALIZED EAST OF HIGHWAY
183. BUT FARTHER WEST ACROSS THE AREA...WHERE MID LEVEL
PRECIPITATION HAS BEEN ONGOING FOR SEVERAL HOURS NOW AND CEILINGS
ARE LOWERING CLOSER TO 2000FT AGL..CONFIDENCE IS SOMEWHAT HIGHER
OF PRECIPITATION BEING REALIZED AT THE SURFACE. GIVEN ALL
THIS...WENT AHEAD WITH CHANCE POPS ACROSS OUR FAR WEST...ROUGHLY
WEST OF HIGHWAY 183...WITH SLIGHT CHANCE POPS FARTHER EAST. THE
RAP...NAM AND OPERATIONAL GFS ALL SUGGEST THE MID LEVEL TROUGH
AXIS WILL BEGIN CLEARING THE AREA BY 15Z...THUS ALLOWING THE BULK
OF THE OMEGA AND MID LEVEL FRONTOGENESIS TO ALSO PUSH EAST OF OUR
AREA BY LATE MORNING OR MIDDAY. QPF FIELDS FROM VARIOUS MODELS
SUGGEST VERY LIGHT PRECIPITATION MAY STILL BE REALIZED OVER
PORTIONS OF OUR AREA BEYOND 15Z...BUT GIVEN THE LIMITED FORCING BY
THIS TIME OPTED TO ONLY GO WITH 20% POPS 15-18Z...AND ISOLATED
FLURRIES AND SPRINKLES AFTER 18Z.
ALTHOUGH A FEW LOCATIONS ACROSS SOUTHWESTERN NEBRASKA AND
NORTHWESTERN KANSAS HAVE REPORTED RECEIVING ONE OR TWO INCHES OF
SNOW SINCE 06Z...CURRENT RETURNS FROM KUEX...KLNX AND KGLD ALL
SUGGEST THE ONGOING PRECIPITATION IS FAIRLY LIGHT AT THIS HOUR AND
CURRENTLY DO NOT EXPECT THIS TREND TO CHANGE AS THIS ACTIVITY
WORKS INTO OUR AREA. GIVEN ALL THIS...WILL GO AHEAD AND PRESENT A
COUPLE TENTHS OF AN INCH OF SNOWFALL TO MOST LOCATIONS WEST OF
HIGHWAY 183...WITH A FEW LOCATIONS ACROSS WESTERN DAWSON...WESTERN
GOSPER AND WESTERN FURNAS COUNTIES CLOSER TO A HALF INCH.
IT IS WORTH NOTING THAT FORECAST PROXIMITY SOUNDINGS FROM OUR
EAST/NORTHEASTERN CWA PER THE NAM AND RAP SUGGEST AND ELEVATED
WARM LAYER NEAR 850MB COULD PRESENT TEMPERATURES SLIGHTLY ABOVE
FREEZING THROUGH 15Z WHILE SURFACE TEMPERATURES REMAIN BELOW
FREEZING. 850MB TEMPERATURES FOR ALL SITES ACROSS OUR CWA ARE
EXPECTED TO FALL BELOW FREEZING BY NO LATER THAN 15Z HOWEVER...PER
THE NAM AND RAP...AND GIVEN THE LOW CONFIDENCE/VERY LOW CHANCE OF
MEASURABLE PRECIPITATION ACTUALLY BEING OBSERVED THAT FAR EAST
BEFORE 15Z...OPTED TO KEEP ANY MENTION OF -ZR OUT OF THE FORECAST.
THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL SUGGEST YET
ANOTHER MID LEVEL SHORT WAVE WILL PUSH OVER THE CENTRAL PLAINS
TONIGHT. FORECAST PROXIMITY SOUNDINGS FROM ACROSS THE CWA PER THE
NAM AND OPERATIONAL GFS SUGGEST HOWEVER THAT TROPOSPHERIC MOISTURE
WILL BE TOO LACKING FOR PRECIPITATION PRODUCTION AND AS A
RESULT...LEFT TONIGHT DRY. SUBTLE MID AND UPPER LEVEL RIDGING IS
EXPECTED TO MOVE INTO THE CENTRAL CONUS MONDAY THROUGH TUESDAY
NIGHT. THE RESULTANT LACK IN OVERALL KINEMATIC FORCING SHOULD THEN
PRESENT DRY CONDITIONS TO FINISH OUT THE SHORT TERM FORECAST
PERIOD.
WEAK LOW LEVEL COLD AIR ADVECTION ACROSS THE REGION TODAY SHOULD
PRESENT SLIGHTLY COOLER TEMPERATURES TODAY WHEN COMPARED TO
YESTERDAY...WITH AFTERNOON HIGHS IN THE 30S AND 40S CURRENTLY
FORECAST. WEAK LOW LEVEL WARM AIR ADVECTION AND A DOWN-SLOPING
COMPONENT TO THE LOW LEVEL WIND FIELD SHOULD THEN PRESENT A SUBTLE
WARMING TREND TO FINISH OUT THE SHORT TERM FORECAST PERIOD...WITH
HIGHS IN THE 40S AND 50S EXPECTED MONDAY AND TUESDAY.
LONG TERM...WEDNESDAY THROUGH SATURDAY
THE MAIN STORY: WED CONTINUES TO THREATEN SOME WINTRY WX AND
SLIPPERY TRAVEL FOR PART OF THE FCST AREA WITH TEMPS AVERAGING
SEASONABLY COLD THROUGH THE PERIOD.
PATTERN: THE HEMISPHERIC HGT ANOMALIES ARE LIKELY TO MAINTAIN
-NAO/ -PNA CONFIGURATION...ESSENTIALLY WORKING AGAINST EACH OTHER
TO BRING ANY REAL ARCTIC COLD DEEP INTO THE CONUS. HOWEVER...THE E
PACIFIC LONGWAVE TROF WILL CONTINUE TO DELIVER OCCASIONAL PCPN
THREATS. THE FIRST OCCURRED WITH THIS PAST FRI NIGHT`S RAINFALL
/WHICH BROUGHT WIDESPREAD 0.5 TO 0.75"/. THE NEXT ARRIVES WED AND
THE PATTERN LOOKS FAVORABLE FOR ANOTHER DURING THE WEEK OF
CHRISTMAS.
HAZARDS: WE CONTINUE TO SEE POTENTIAL FOR SOME ACCUMULATING SNOW
WED-WED EVE. THE THREAT CONTINUES HIGHLIGHTED IN THE HWO.
PCPN: WED-WED EVE CONFIDENCE IS HIGH FOR A LIGHT SNOWFALL EVENT.
CONFIDENCE IS AVERAGE FOR A MODERATE SNOWFALL...PROBABLY S AND E
OF HASTINGS "IF" IT WAS TO OCCUR.
THE DAILY DETAILS...
LOW TEMPS ALL PERIODS WERE LOWERED TO BIAS CORRECTED ALL-BLEND
GUIDANCE. THIS COORDINATED WITH LBF SINCE THIS LOWERED TEMPS MOST
OVER OUR NW COUNTIES. WED HIGH TEMPS WERE ALSO LOWERED TO MEX
TEMPS AND WAS COORDINATED WITH ALL SURROUNDING OFFICES.
DETERMINISTIC MODELS AND NAEFS/EC ENSEMBLE MEANS CONTINUE TO
SUGGEST HIGH CONFIDENCE IN LEE CYCLOGENESIS WED...WITH THE LOW
EJECTING ACROSS KS /OR NRN OK?/ INTO THE MID MS VALLEY.
HOWEVER...ENSEMBLE SPREAD OF 8-10 MB EXISTS NW OF THE MEAN SFC LOW
POSITION... SUGGESTING DIFFERENCES IN TIMING/LOCATION AMONG THE
VARIOUS POSSIBLE OUTCOMES IN THE GUIDANCE ENVELOPE.
THERE ARE A COUPLE GFS ENSEMBLE MEMBERS THAT OFFER 0.5" OF COMMA-
HEAD QPF IN VICINITY OF HWY 81...SIMILAR TO THE 00Z/15 EC. SO
ALTHO IT/S A LOW PROBABILITY...SOME POTENTIAL CONTINUES FOR
WARNING SNOWFALL AMOUNTS OVER OR SOMEWHERE NEARBY OUR FCST AREA.
FOR NOW GFS ENSEMBLE PROBABILITIES ARE HIGH /70 PERCENT/ FOR 0.1"
IN 24 HRS ALONG AND E OF HWY 281.
REGARDLESS OF HOW MUCH SNOW FALLS...WED IS LIKELY TO BE A RAW
NASTY DAY WITH A SHARP N WIND AND FALLING AFTERNOON TEMPS.
FCST FOR WED IS ESSENTIALLY CLOUDY IN CAA WITH -SN DEVELOPING IN
INCREASINGLY GUSTY NE WINDS. NOT SURE IT SNOWS EVERYWHERE. TRACK
DEPENDENT. BEST GUESS AT THIS POINT IS LOWEST CHANCE FOR
MEASURABLE SNOW IS N AND W OF GRI. TEMPS PROBABLY RISE LITTLE FROM
MORNING LOWS AND THEN FALL AFTER MIDDAY.
WED NGT: ANY SNOW ENDS PROBABLY BY MIDNIGHT. CLEARING FROM THE SW.
A BLUSTERY NIGHT WITH WIND CHILLS AS LOW AS -5F AT TIMES.
WINDS WERE INCREASED ABOVE GUIDANCE 12 PM WED TO 12 PM THU.
THU: UPPER TROF TRANSITIONS TO NW FLOW. SUNNY. BLUSTERY N WINDS
EVENTUALLY SUBSIDE AS SFC RIDGE MOVES IN LATE. NEAR NORMAL TEMPS
BUT IT WILL FEEL COLD GIVEN THE MILD DEC THUS FAR...ESPECIALLY
WITH A BITING N WIND AND WIND CHILLS NEAR ZERO IN THE
MRNG...ESPECIALLY N AND W OF GRI.
FRI: SUNNY AND PROBABLY 5F ABOVE NORMAL WITH LIGHT SW WINDS.
SAT: QUITE A BIT OF SPREAD WITH AMPLITUDE/POSITION OF THE RIDGE
BUT MOST MODELS/ENSEMBLE MEMBERS SUGGEST A DRY COLD FRONTAL
PASSAGE. FOR NOW SEASONABLY COLD TEMPS.
ARCTIC COLD: WE/VE NOTICED VARIOUS RUNS OF THE GFS/EC HAVE
THREATENED TO BRING DOWN SOME BITTER ARCTIC COLD THE LAST WEEK OF
DEC. THE GFS ENSEMBLES CONTINUE TO HINT AT A POSSIBLE 2-3 DAY
SPELL OF COLD TEMPS IN THIS TIMEFRAME. THE DETERMINISTIC 5-DAY
MEANS FROM THE LAST COUPLE RUNS OF THE GFS/EC WANT TO DEVELOP A
HUDSON BAY LOW UPSTREAM OF THE GREENLAND BLOCK. WOULD LIKE TO SEE
MORE ENSEMBLE SUPPORT BEFORE GETTING HOPES US. HOWEVER...WE WOULD
NEED SOME HELP EITHER VIA A TRANSITION TO A +PNA /WRN N AMERICA
RIDGING/ OR SOME HIGH- LATITUDE RIDGING OVER AK. THERE ARE SOME
HINTS OF THIS IN THE ENSEMBLES.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
LONG TERM UPDATE...HEINLEIN
AVIATION/SHORT TERM...BRYANT
LONG TERM...HALBLAUB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
433 AM CST SUN DEC 16 2012
.SHORT TERM...THROUGH 12Z WEDNESDAY. EVENING UPPER AIR ANALYSIS
INDICATES A LONGWAVE TROUGH OVER THE WESTERN HALF OF THE CONUS
WITH QUASI- ZONAL FLOW ACROSS THE EAST. MID AND UPPER LEVEL JET
ENERGY EXTENDS FROM WEST-TEXAS...EAST/NORTHEAST INTO THE SOUTHERN
PLAINS AND LOWER MISSISSIPPI VALLEY...AND THEN FARTHER EAST INTO
THE SOUTHEASTERN CONUS. MID AND UPPER LEVEL TROPOSPHERIC FLOW OVER
OUR AREA REMAINS FAIRLY WEAK AS A RESULT...MAXING OUT AT AROUND
60KTS NEAR 200MB PER 00Z SOUNDING DATA FROM KLBF. WATER VAPOR
IMAGERY SHOWS PLENTY OF MID LEVEL MOISTURE ADVANCING
EAST/NORTHEAST ALONG THE MID TO UPPER LEVEL JET AXIS ACROSS THE
SOUTH AND SOUTHEASTERN CONUS...WITH DRIER MID LEVEL AIR NOTED
FARTHER NORTH. WATER VAPOR IMAGERY ALSO INDICATES A COMPACT MID
LEVEL SHORT WAVE OVER COLORADO...BEGINNING TO EJECT OUT FROM THE
MAIN LONGWAVE TROUGH. AT THE SURFACE A RIDGE OF HIGH PRESSURE IS
NOTED EXTENDING FROM THE NORTHERN HIGH PLAINS...SOUTH/SOUTHEAST
INTO THE CENTRAL PLAINS. A COLD FRONT IS ALSO NOTED EXTENDING FROM
SOUTHWEST TO NORTHEAST ACROSS KANSAS...SOUTHWESTERN MISSOURI AND
IOWA. THE LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE
NORTHWEST AS A RESULT. RADAR DATA FROM KUEX...KLNX AND KGLD
CONTINUE TO SHOW PRECIPITATION OVER SOUTHWESTERN NEBRASKA AND
NORTHWESTERN KANSAS...WITH SNOW BEING REPORTED OVER SOME AREAS AS
WELL. FOR LOCATIONS ACROSS OUR WESTERN CWA...WHERE KUEX HAS
INDICATED PRECIPITATION FOR THE PAST FEW HOURS...PRECIPITATION AT
THE SURFACE HAS YET TO BE REPORTED AS THE LOWER TROPOSPHERE STILL
APPEARS TOO DRY FOR SUCH ACTIVITY TO BE REALIZED.
GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL
SUGGEST THE MID LEVEL SHORT WAVE...APPROACHING OUR AREA FROM
COLORADO...WILL CONTINUE PUSHING ACROSS THE CENTRAL PLAINS DURING
THE DAY TODAY. DPVA AND WEAK MID LEVEL THERMAL ADVECTION AHEAD OF
THE MID LEVEL TROUGH AXIS...WORKING IN CONCERT WITH AN AXIS OF
FRONTOGENESIS NEAR 700MB...SHOULD SUSTAIN PRECIPITATION PRODUCTION
OVER NORTHWESTERN KANSAS AND SOUTHWESTERN NEBRASKA THROUGH THE
NEXT FEW HOURS...WITH PRECIPITATION PERHAPS MAKING IT TO THE
SURFACE ACROSS WESTERN PORTIONS OF OUR AREA AS WELL. FORECAST
PROXIMITY SOUNDINGS FROM ACROSS MUCH OF OUR CWA...PER THE NAM AND
OPERATIONAL GFS...SUGGEST THE LOWER TROPOSPHERE WILL HAVE TO DO
QUITE A BIT OF SATURATING FARTHER EAST BEFORE PRECIPITATION IS
REALIZED AT THE SURFACE...THUS CONFIDENCE IS NOT ALL THAT HIGH
THAT ANY MEASURABLE PRECIPITATION WILL BE REALIZED EAST OF HIGHWAY
183. BUT FARTHER WEST ACROSS THE AREA...WHERE MID LEVEL
PRECIPITATION HAS BEEN ONGOING FOR SEVERAL HOURS NOW AND CEILINGS
ARE LOWERING CLOSER TO 2000FT AGL..CONFIDENCE IS SOMEWHAT HIGHER
OF PRECIPITATION BEING REALIZED AT THE SURFACE. GIVEN ALL
THIS...WENT AHEAD WITH CHANCE POPS ACROSS OUR FAR WEST...ROUGHLY
WEST OF HIGHWAY 183...WITH SLIGHT CHANCE POPS FARTHER EAST. THE
RAP...NAM AND OPERATIONAL GFS ALL SUGGEST THE MID LEVEL TROUGH
AXIS WILL BEGIN CLEARING THE AREA BY 15Z...THUS ALLOWING THE BULK
OF THE OMEGA AND MID LEVEL FRONTOGENESIS TO ALSO PUSH EAST OF OUR
AREA BY LATE MORNING OR MIDDAY. QPF FIELDS FROM VARIOUS MODELS
SUGGEST VERY LIGHT PRECIPITATION MAY STILL BE REALIZED OVER
PORTIONS OF OUR AREA BEYOND 15Z...BUT GIVEN THE LIMITED FORCING BY
THIS TIME OPTED TO ONLY GO WITH 20% POPS 15-18Z...AND ISOLATED
FLURRIES AND SPRINKLES AFTER 18Z.
ALTHOUGH A FEW LOCATIONS ACROSS SOUTHWESTERN NEBRASKA AND
NORTHWESTERN KANSAS HAVE REPORTED RECEIVING ONE OR TWO INCHES OF
SNOW SINCE 06Z...CURRENT RETURNS FROM KUEX...KLNX AND KGLD ALL
SUGGEST THE ONGOING PRECIPITATION IS FAIRLY LIGHT AT THIS HOUR AND
CURRENTLY DO NOT EXPECT THIS TREND TO CHANGE AS THIS ACTIVITY
WORKS INTO OUR AREA. GIVEN ALL THIS...WILL GO AHEAD AND PRESENT A
COUPLE TENTHS OF AN INCH OF SNOWFALL TO MOST LOCATIONS WEST OF
HIGHWAY 183...WITH A FEW LOCATIONS ACROSS WESTERN DAWSON...WESTERN
GOSPER AND WESTERN FURNAS COUNTIES CLOSER TO A HALF INCH.
IT IS WORTH NOTING THAT FORECAST PROXIMITY SOUNDINGS FROM OUR
EAST/NORTHEASTERN CWA PER THE NAM AND RAP SUGGEST AND ELEVATED
WARM LAYER NEAR 850MB COULD PRESENT TEMPERATURES SLIGHTLY ABOVE
FREEZING THROUGH 15Z WHILE SURFACE TEMPERATURES REMAIN BELOW
FREEZING. 850MB TEMPERATURES FOR ALL SITES ACROSS OUR CWA ARE
EXPECTED TO FALL BELOW FREEZING BY NO LATER THAN 15Z HOWEVER...PER
THE NAM AND RAP...AND GIVEN THE LOW CONFIDENCE/VERY LOW CHANCE OF
MEASURABLE PRECIPITATION ACTUALLY BEING OBSERVED THAT FAR EAST
BEFORE 15Z...OPTED TO KEEP ANY MENTION OF -ZR OUT OF THE FORECAST.
THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL SUGGEST YET
ANOTHER MID LEVEL SHORT WAVE WILL PUSH OVER THE CENTRAL PLAINS
TONIGHT. FORECAST PROXIMITY SOUNDINGS FROM ACROSS THE CWA PER THE
NAM AND OPERATIONAL GFS SUGGEST HOWEVER THAT TROPOSPHERIC MOISTURE
WILL BE TOO LACKING FOR PRECIPITATION PRODUCTION AND AS A
RESULT...LEFT TONIGHT DRY. SUBTLE MID AND UPPER LEVEL RIDGING IS
EXPECTED TO MOVE INTO THE CENTRAL CONUS MONDAY THROUGH TUESDAY
NIGHT. THE RESULTANT LACK IN OVERALL KINEMATIC FORCING SHOULD THEN
PRESENT DRY CONDITIONS TO FINISH OUT THE SHORT TERM FORECAST
PERIOD.
WEAK LOW LEVEL COLD AIR ADVECTION ACROSS THE REGION TODAY SHOULD
PRESENT SLIGHTLY COOLER TEMPERATURES TODAY WHEN COMPARED TO
YESTERDAY...WITH AFTERNOON HIGHS IN THE 30S AND 40S CURRENTLY
FORECAST. WEAK LOW LEVEL WARM AIR ADVECTION AND A DOWN-SLOPING
COMPONENT TO THE LOW LEVEL WIND FIELD SHOULD THEN PRESENT A SUBTLE
WARMING TREND TO FINISH OUT THE SHORT TERM FORECAST PERIOD...WITH
HIGHS IN THE 40S AND 50S EXPECTED MONDAY AND TUESDAY.
.LONG TERM...WEDNESDAY THROUGH SATURDAY
THE MAIN STORY: WED CONTINUES TO THREATEN SOME WINTRY WX AND
SLIPPERY TRAVEL FOR PART OF THE FCST AREA WITH TEMPS AVERAGING
SEASONABLY COLD THROUGH THE PERIOD.
PATTERN: THE HEMISPHERIC HGT ANOMALIES ARE LIKELY TO MAINTAIN
-NAO/ -PNA CONFIGURATION...ESSENTIALLY WORKING AGAINST EACH OTHER
TO BRING ANY REAL ARCTIC COLD DEEP INTO THE CONUS. HOWEVER...THE E
PACIFIC LONGWAVE TROF WILL CONTINUE TO DELIVER OCCASIONAL PCPN
THREATS. THE FIRST OCCURRED WITH THIS PAST FRI NIGHT`S RAINFALL
/WHICH BROUGHT WIDESPREAD 0.5 TO 0.75"/. THE NEXT ARRIVES WED AND
THE PATTERN LOOKS FAVORABLE FOR ANOTHER DURING THE WEEK OF
CHRISTMAS.
HAZARDS: WE CONTINUE TO SEE POTENTIAL FOR SOME ACCUMULATING SNOW
WED-WED EVE. THE THREAT CONTINUES HIGHLIGHTED IN THE HWO.
PCPN: WED-WED EVE CONFIDENCE IS HIGH FOR A LIGHT SNOWFALL EVENT.
CONFIDENCE IS AVERAGE FOR A MODERATE SNOWFALL...PROBABLY S AND E
OF HASTINGS "IF" IT WAS TO OCCUR.
THE DAILY DETAILS...
LOW TEMPS ALL PERIODS WERE LOWERED TO BIAS CORRECTED ALL-BLEND
GUIDANCE. THIS COORDINATED WITH LBF SINCE THIS LOWERED TEMPS MOST
OVER OUR NW COUNTIES. WED HIGH TEMPS WERE ALSO LOWERED TO MEX
TEMPS AND WAS COORDINATED WITH ALL SURROUNDING OFFICES.
DETERMINISTIC MODELS AND NAEFS/EC ENSEMBLE MEANS CONTINUE TO
SUGGEST HIGH CONFIDENCE IN LEE CYCLOGENESIS WED...WITH THE LOW
EJECTING ACROSS KS /OR NRN OK?/ INTO THE MID MS VALLEY.
HOWEVER...ENSEMBLE SPREAD OF 8-10 MB EXISTS NW OF THE MEAN SFC LOW
POSITION... SUGGESTING DIFFERENCES IN TIMING/LOCATION AMONG THE
VARIOUS POSSIBLE OUTCOMES IN THE GUIDANCE ENVELOPE.
THERE ARE A COUPLE GFS ENSEMBLE MEMBERS THAT OFFER 0.5" OF COMMA-
HEAD QPF IN VICINITY OF HWY 81...SIMILAR TO THE 00Z/15 EC. SO
ALTHO IT/S A LOW PROBABILITY...SOME POTENTIAL CONTINUES FOR
WARNING SNOWFALL AMOUNTS OVER OR SOMEWHERE NEARBY OUR FCST AREA.
FOR NOW GFS ENSEMBLE PROBABILITIES ARE HIGH /70 PERCENT/ FOR 0.1"
IN 24 HRS ALONG AND E OF HWY 281.
REGARDLESS OF HOW MUCH SNOW FALLS...WED IS LIKELY TO BE A RAW
NASTY DAY WITH A SHARP N WIND AND FALLING AFTERNOON TEMPS.
FCST FOR WED IS ESSENTIALLY CLOUDY IN CAA WITH -SN DEVELOPING IN
INCREASINGLY GUSTY NE WINDS. NOT SURE IT SNOWS EVERYWHERE. TRACK
DEPENDENT. BEST GUESS AT THIS POINT IS LOWEST CHANCE FOR
MEASURABLE SNOW IS N AND W OF GRI. TEMPS PROBABLY RISE LITTLE FROM
MORNING LOWS AND THEN FALL AFTER MIDDAY.
WED NGT: ANY SNOW ENDS PROBABLY BY MIDNIGHT. CLEARING FROM THE SW.
A BLUSTERY NIGHT WITH WIND CHILLS AS LOW AS -5F AT TIMES.
WINDS WERE INCREASED ABOVE GUIDANCE 12 PM WED TO 12 PM THU.
THU: UPPER TROF TRANSITIONS TO NW FLOW. SUNNY. BLUSTERY N WINDS
EVENTUALLY SUBSIDE AS SFC RIDGE MOVES IN LATE. NEAR NORMAL TEMPS
BUT IT WILL FEEL COLD GIVEN THE MILD DEC THUS FAR...ESPECIALLY
WITH A BITING N WIND AND WIND CHILLS NEAR ZERO IN THE
MRNG...ESPECIALLY N AND W OF GRI.
FRI: SUNNY AND PROBABLY 5F ABOVE NORMAL WITH LIGHT SW WINDS.
SAT: QUITE A BIT OF SPREAD WITH AMPLITUDE/POSITION OF THE RIDGE
BUT MOST MODELS/ENSEMBLE MEMBERS SUGGEST A DRY COLD FRONTAL
PASSAGE. FOR NOW SEASONABLY COLD TEMPS.
ARCTIC COLD: WE/VE NOTICED VARIOUS RUNS OF THE GFS/EC HAVE
THREATENED TO BRING DOWN SOME BITTER ARCTIC COLD THE LAST WEEK OF
DEC. THE GFS ENSEMBLES CONTINUE TO HINT AT A POSSIBLE 2-3 DAY
SPELL OF COLD TEMPS IN THIS TIMEFRAME. THE DETERMINISTIC 5-DAY
MEANS FROM THE LAST COUPLE RUNS OF THE GFS/EC WANT TO DEVELOP A
HUDSON BAY LOW UPSTREAM OF THE GREENLAND BLOCK. WOULD LIKE TO SEE
MORE ENSEMBLE SUPPORT BEFORE GETTING HOPES US. HOWEVER...WE WOULD
NEED SOME HELP EITHER VIA A TRANSITION TO A +PNA /WRN N AMERICA
RIDGING/ OR SOME HIGH- LATITUDE RIDGING OVER AK. THERE ARE SOME
HINTS OF THIS IN THE ENSEMBLES.
&&
.PREV DISCUSSION... /ISSUED 1107 PM CST SAT DEC 15 2012/
AVIATION...06Z KGRI TAF. VFR CONDITIONS EXPECTED THROUGH THE NEXT
24 HOURS. CEILINGS BETWEEN 4000FT AGL AND 8000FT AGL WILL PERSIST
AT THE TERMINAL THROUGH SUNDAY AFTERNOON...WITH HIGH LEVEL CLOUDS
EXPECTED THEREAFTER. THE SURFACE WIND WILL REMAIN FROM THE
NORTHWEST TONIGHT BEFORE BECOMING LIGHT AND VARIABLE DURING THE
DAY SUNDAY. VISIBILITY RESTRICTIONS ARE NOT EXPECTED THROUGH THE
NEXT 24 HOURS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM/AVIATION...BRYANT
LONG TERM...HALBLAUB
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
923 AM EST SUN DEC 16 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL SLIDE INTO THE AREA THIS AFTERNOON AND
EVENING. LOW PRESSURE WILL DEVELOP ALONG THIS FRONT AND MOVE
ACROSS THE AREA MONDAY. HIGH PRESSURE WILL BUILD IN TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW LEVEL MOISTURE WILL REMAIN IN PLACE ACROSS THE CWA TODAY.
CEILINGS HAVE BEGUN TO LIFT SLIGHTLY THIS MORNING...AND RADAR
ECHOES HAVE DIMINISHED IN COVERAGE AS WELL. A SLIGHT CHANCE OF
SHOWERS WILL BE KEPT IN THE FORECAST...MAINLY IN THE EAST AND JUST
FOR THE NEXT FEW HOURS...BEFORE LIMITING ANY CHANCE OF
PRECIPITATION TO THE FAR SOUTHEAST THROUGH THE AFTERNOON HOURS.
THE LATEST HRRR RUNS ARE SHOWING THAT ANY CONVECTION THAT DEVELOPS
WILL OCCUR NEAR OR AFTER 00Z AND WILL LIKELY BE LIMITED TO THE
SOUTH AND SOUTHEAST. GIVEN THE REMAINING UNCERTAINTY IN BOTH
FORCING AND INSTABILITY...THERE APPEARS TO BE NO REASON TO
INCREASE POPS THIS EVENING (THOUGH A SLIGHTLY HIGHER CHANCE WILL
EXIST LATER IN THE OVERNIGHT HOURS).
TEMPERATURES WERE MOSTLY ON TRACK...WITH SOME SLIGHT UPWARD
ADJUSTMENTS MADE IN THE SOUTH. WARM ADVECTION WILL DOMINATE THE
TEMPERATURE CURVE TODAY...WITH ESSENTIALLY ZERO DIRECT SUNLIGHT
EXPECTED.
PREVIOUS DISCUSSION >
SOUTHERLY FLOW WILL CONTINUE ACROSS THE REGION TODAY. PLENTY OF
LOW LEVEL MOISTURE IN PLACE ALTHOUGH THERE SHOULD BE SOME BREAKS
IN THE CLOUDS ESPECIALLY LATER IN THE DAY. A WEAK COLD FRONT WILL
PUSH INTO THE REGION LATE THIS AFTERNOON. AND THERE WILL BE A WEAK
MID LEVEL IMPULSE TRACKING ACROSS THE AREA. BUT OVERALL FORCING IS
MINIMAL. SO ONLY KEPT SLIGHT CHANCE POPS IN FOR TODAY.
TEMPERATURES WILL BE WELL ABOVE NORMAL WITH A MOS BLEND USED AS A
BASE FOR HIGHS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
BOUNDARY WILL WORK FURTHER INTO THE FORECAST AREA TONIGHT BEFORE
STALLING AS LOW PRESSURE DEVELOPS ALONG THE FRONT OFF TO THE
SOUTHWEST. AS THE LOW APPROACHES LATE TONIGHT EXPECT SHOWERS TO
DEVELOP IN THE SOUTHERN COUNTIES. THE LOW WILL CONTINUE TO TRAVEL
ALONG THE FRONT AND ACROSS THE REGION ON MONDAY. MODELS ARE
TRENDING TOWARDS A LESS DEVELOPED LOW WHICH SHOULD KEEP THE
GREATER COVERAGE OF SHOWERS FROM SPREADING TOO FAR NORTHWEST. BUT
STILL ENOUGH UNCERTAINTY TO KEEP CHANCE POPS GOING ALL THE WAY
INTO WEST CENTRAL OHIO. THERE WILL BE SOME INSTABILITY ALONG AND
SOUTH OF THE FRONT SO DID INCLUDE A CHANCE OF THUNDERSTORMS THERE.
A SHORT WAVE WILL TRAVEL ACROSS THE REGION MONDAY NIGHT AND WITH
MOISTURE STILL LINGERING IN THE AREA THAT MAY GENERATE SOME
ADDITIONAL SHOWERS AREA WIDE. AFTER IT PASSES RIDGING WILL
TEMPORARILY MOVE IN ALLOWING FOR SOME DRYING.
WARMER GUIDANCE LOOKED MORE REASONABLE FOR TONIGHT BUT A BLEND WAS
USED MONDAY NIGHT. LEANED TOWARDS COOLER GUIDANCE FOR HIGH
TEMPERATURES BOTH DAYS.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
UPPER RIDGING WILL CONTINUE INTO WEDNESDAY AHEAD OF AN APPROACHING
DEEPENING TROUGH. SO EXPECT DRY AND UNSEASONABLY WARM CONDITIONS
ONCE AGAIN. AS THE UPPER SYSTEM PIVOTS NORTHEAST TOWARDS THE
REGION THE ASSOCIATED SURFACE LOW WILL PUSH A WARM FRONT THROUGH
THE AREA WEDNESDAY NIGHT. THIS WILL LEAD TO STEADY OR RISING
TEMPERATURES OVERNIGHT. SHOWERS WILL SPREAD IN FROM THE WEST LATE
WEDNESDAY NIGHT AND SWEEP ACROSS THE REGION ON THURSDAY. WITH WEAK
INSTABILITY FORECAST AT THIS POINT BUT FAIRLY STRONG DYNAMICS...
CANNOT RULE OUT SOME THUNDER ALTHOUGH IT IS NOT INCLUDED IN THE
FORECAST YET. THE LOW WILL LIFT NORTH OF THE AREA BUT AFTER A
STRONG COLD FRONT SWEEPS THROUGH THE TEMPERATURES WILL FALL IN THE
AFTERNOON.
00Z GUIDANCE HAS COME INTO AGREEMENT IN KEEPING THIS SYSTEM
PROGRESSIVE. SO THERE WILL ONLY BE A BRIEF WINDOW FOR WRAP AROUND
AND LAKE ENHANCED SNOW SHOWERS TO AFFECT THE REGION THURSDAY NIGHT
AND FRIDAY. HIGH PRESSURE WILL BUILD IN WITH TEMPERATURES AT OR
SLIGHTLY BELOW SEASONAL NORMALS.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
MVFR AND VFR CIGS WILL BE AROUND THE AREA TAF SITES THIS MORNING
BEFORE VFR CONDITIONS GRADUALLY RETURN TO THE AREA THIS
AFTERNOON. SOME DRIZZLE OR LIGHT SHOWER ACTIVITY WILL ALSO BE
PRESENT ACROSS THE AREA THIS MORNING BEFORE MOVING OUT OF THE TAF
SITES. WINDS WILL PICK UP THIS AFTERNOON WITH SOME WIND GUSTS
AROUND 20 KNOTS POSSIBLE. WINDS WILL DECREASE ACROSS THE TAF SITES
THIS EVENING AND CIGS WILL LOWER AS AN AREA OF LOW PRESSURE
APPROACHES THE REGION FROM THE SOUTH. AS THIS AREA OF LOW PRESSURE
NEARS THE REGION TONIGHT RAIN SHOWERS WILL MOVE INTO THE SOUTHERN
TAF SITES. IN ADDITION...CIGS AND VSBYS WILL LOWER ACROSS THE
AREA.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES POSSIBLE MONDAY INTO
TUESDAY AND THEN AGAIN ON THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...HATZOS/
SHORT TERM...
LONG TERM...
AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
542 AM CST SUN DEC 16 2012
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
305 AM CST SUN DEC 16 2012
THE MAIN FOCUS OVER THE NEXT FEW DAYS IS ON THE DEPARTING
PRECIPITATION TODAY FOLLOWED BY THE CHANCE FOR SNOW ON TUESDAY.
LIGHT RAIN/DRIZZLE AND LIGHT SNOW WILL COME TO AN END FROM WEST TO
EAST TODAY AS A MID LEVEL SHORTWAVE TROUGH PROPAGATES TO THE NORTHEAST
INTO THE GREAT LAKES. AS OF 2 AM...SURFACE OBS AND DUAL POL RADAR
SHOWED THE RAIN/SNOW LINE FROM JUST WEST OF EAU CLAIRE WISCONSIN
DOWN TO WINONA MINNESOTA AND DECORAH IOWA. THE TRANSITION TO LIGHT
SNOW WILL BE RATHER BRIEF AND THEREFORE ANY SNOW ACCUMULATIONS
WILL BE ON THE LIGHT SIDE. EARLIER RUNS OF THE RAP HAD SHOWN THE
POSSIBILITY OF SOME FREEZING DRIZZLE OCCURRING AS THE SNOW CAME TO
AN END...BUT OBSERVATIONS/RADAR UPSTREAM IS NOT SHOWING ANY OF
THIS. DENSE FOG FORMED ACROSS MUCH OF THE REGION OVERNIGHT AS A
RESULT OF HIGH LOW LEVEL MOISTURE DUE TO RECENT RAIN AND SNOW MELT
ALONG WITH THE CORE OF A SURFACE LOW OVERHEAD WHICH PROVIDED
LIGHT TO CALM WINDS. AS THE COLD FRONT EXTENDING SOUTH FROM THE
LOW MOVES THROUGH...WINDS WILL PICK UP AND THE DENSE FOG WILL MIX
OUT WITH VISIBILITY IMPROVING. WITH VISIBILITY STILL LESS THAN A
QUARTER MILE IN NORTH CENTRAL WISCONSIN...WILL LET THE ADVISORY
ROLL FOR NOW WITH IT EXPIRING AT 6 AM...BUT MAY BE ABLE TO CLEAR
IT EARLY.
NOT THE CLEAREST OF WEATHER PATTERNS EXPECTED THROUGH THE NEXT FEW
DAYS WITH SUBTLE SYSTEMS MOVING INTO THE REGION THROUGH THE
SOUTHWEST-WESTERLY FLOW ALOFT. A WEAK MID LEVEL TROUGH WILL MOVE
THROUGH TODAY...BUT WILL ONLY ADD CLOUD COVER TO THE REGION.
16.00Z NAM/GFS SOUNDINGS SHOW THAT THE FORCING IS NOT VERY STRONG
AND THE DRY LAYER IS TOO DEEP FOR SEEDER FEEDER TO PRODUCE SOME
SNOW. A SURFACE RIDGE OF HIGH PRESSURE WILL THEN MOVE THROUGH THE
REGION TONIGHT INTO MONDAY BEFORE THE NEXT SYSTEM TAKES SHAPE IN
THE NORTHERN PLAINS. MUCH OF THE FORCING FOR THIS SYSTEM WILL BE
FROM THE LOW LEVEL WARM AIR ADVECTION...BUT THERE ALSO IS A MID
LEVEL TROUGH THAT ROTATES NORTHWARD INTO SOUTHERN CANADA OVER THE
SAME TIME FRAME. THE 16.00Z ECMWF IS THE STRONGEST WITH HAVING A
SURFACE LOW MOVE THROUGH...BUT OVERALL QPF REMAINS ON THE LIGHT
SIDE AT LESS THAN A TENTH OF AN INCH. PRECIPITATION TYPE WILL
MAINLY BE LIGHT SNOW WITH ANY ACCUMULATIONS LIKELY LESS THAN AN
INCH.
.LONG TERM...WEDNESDAY THROUGH SATURDAY
305 AM CST SUN DEC 16 2012
THE FOCUS FROM MID WEEK INTO NEXT WEEKEND CONTINUES TO BE WITH THE
POTENTIAL FOR A WINTER STORM WEDNESDAY NIGHT INTO THURSDAY. WHILE
THE SUITE OF 16.00Z GUIDANCE STILL ADVERTISES THIS DEEPENING
SURFACE LOW MOVING INTO SOUTHERN LAKE MICHIGAN BY THURSDAY
MORNING...THE TREND IS FOR THE MAJOR IMPACTS FROM THIS SYSTEM TO
BE MORE SO FELT TO THE SOUTH AND EAST OF THE FORECAST AREA. THE
FURTHER EAST THAT THIS SYSTEM CONTINUES TO MOVE...THE LOWER OUR
CHANCES BECOME OF SEEING THE HEAVIEST SNOW BAND OCCUR IN THE
FORECAST AREA. BASED ON 16.00Z GUIDANCE...THE WESTERN EDGE OF THE
SNOW APPEARS TO RUN FROM CENTRAL IOWA THROUGH SOUTHEAST MINNESOTA
AND NORTHWEST WISCONSIN. WHILE THE HEAVIEST SNOW BAND MAY BE TO THE
EAST OF THE FORECAST AREA...THE CHANCES FOR SNOW ACROSS THE REGION
STILL LOOK GOOD...SO HAVE BUMPED UP THE PRECIPITATION PROBABILITIES
WEDNESDAY NIGHT INTO THURSDAY. THIS SYSTEM IS CURRENTLY UP NEAR
THE ALEUTIAN ISLANDS WEST OF ALASKA AND WILL BE INTO CALIFORNIA BY
TUESDAY WHICH IS WHEN WE SHOULD HAVE A BETTER HANDLE ON THE
SYSTEMS TRACK.
BEHIND THIS SYSTEM...COLDER AIR WILL GET PULLED DOWN FROM SOUTHERN
CANADA...BUT IT APPEARS TO BE A FAIRLY SHORT LIVED COLD BURST
BEFORE LOW LEVEL WARM AIR ADVECTION STRENGTHENS OUT OF THE
SOUTHWEST ON SATURDAY. DUE TO THIS...HAVE TRENDED SLIGHTLY WARMER
FOR TEMPERATURES INTO THE WEEKEND.
&&
.AVIATION...TODAY AND TONIGHT
541 AM CST SUN DEC 16 2012
THE RAIN AND SNOW HAS ALREADY MOVED OUT OF KRST AND IT WILL MOVE
OUT OF KLSE BY 16.14Z. LOOKING AT THE RADAR RETURNS...IT LOOKS
LIKE THE RAIN AND SNOW WILL NOT CAUSE ANY VISIBILITY RESTRICTIONS.
MEANWHILE THE BR AT KRST SHOULD DISSIPATE BY 16.18Z. BR WILL ONCE
AGAIN DEVELOP AT KRST AROUND 17.02Z AND THEN LINGER THROUGH THE
NIGHT.
WITH THE LOW LEVEL CLOUDS BEING TRAPPED BY A SUBSIDENCE
INVERSION THROUGH THIS TIME PERIOD...KRST WILL REMAIN LIFR/IFR AND
KLSE WILL CONTINUE TO SEE MVFR CEILINGS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
541 AM CST SUN DEC 16 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
338 PM EST SUN DEC 16 2012
.SYNOPSIS...
LOW PRESSURE WILL TRACK FROM THE GREAT LAKES REGION TO SOUTHEASTERN
CANADA INTO MONDAY AND WEAKEN. ANOTHER LOW IS FORECAST TO MOVE
ACROSS OUR AREA MONDAY NIGHT INTO TUESDAY, AND STRENGTHEN AS IT
TRACKS TOWARD NEW ENGLAND AND THE CANADIAN MARITIMES THROUGH
WEDNESDAY. HIGH PRESSURE THEN CENTERED TO OUR SOUTH BRIEFLY BUILDS
IN FOR WEDNESDAY. A STRONG LOW PRESSURE SYSTEM THEN MOVES
NORTHEASTWARD INTO THE GREAT LAKES REGION ON THURSDAY, AND ITS
ASSOCIATED STRONG COLD FRONT SWEEPS ACROSS OUR AREA EARLY FRIDAY.
THIS POTENTIALLY INTENSE STORM THEN SHIFTS INTO NEW ENGLAND AND
EASTERN CANADA DURING THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A VERY TRICKY FCST IS IN STORE OVER THE REGION AS IT HAS BEEN ALL
DAY. A WMFRNT IS LOCATED OVER THE REGION AND IS MOVG LITTLE IN
RESPONSE TO A WAVE FORMING ON IT. THIS WAVE WILL MOVE OUT TO SEA
TONIGHT. WITH THE FRONT OVER THE AREA, EXPECT PDS OF GENLY LIGHT
RAIN FOR THE EARLY PORTION OF TONIGHT, GENLY WARM TEMPS, LIGHT WIND
AND FOG. CONFIDENCE IS LOW ON MANY DETAILS OF THE FCST SUCH AS JUST
HOW THICK AND WIDESPREAD THE FOG WILL BE. ALSO, EACH MDL HAS A
DIFFERENT SOLN ON WHERE THE MOST RAIN WILL BE. THE HRRR SEEMED TO
BE HANDLING IT BEST EARLIER, BUT IS NOW TOO DRY, EVEN THOUGH MOST OF
WHAT IS FALLING IS VERY LIGHT. MOST GUID HAS POPS INCREASING LATER
TONIGHT, AND HAVE THEREFORE, DONE SO FOR THIS FCST.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
THE WMFRNT WILL REMAIN OVER THE REGION OR MOVE A BIT NWD ON MONDAY
AND THERE COULD BE A BREAK IN ANY PRECIP DURG THE AFTN BEFORE
ANOTHER AREA OF LOW PRESSURE APPROACHES FROM THE SW LATER IN THE
DAY. AGAIN, THERE ARE VARIED SOLNS AS TO HOW MUCH AND WHAT AREAS
SEE THE MOST RAIN, AND CONFIDENCE IS LOW OVERALL. TEMPS WILL BE
QUITE WARM ON MONDAY, WITH MANY AREAS IN THE 50S, BUT A DREARY
LOOKING DAY IS IN STORE WITH LOW CLOUDS AND SOME RAIN.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
A RATHER ACTIVE PATTERN IS EXPECTED DURING THIS TIME FRAME. THE
OVERALL SYNOPTIC SETUP IS COMPRISED OF AN UPPER-LEVEL TROUGH IN THE
GREAT LAKES MONDAY NIGHT THAT SHIFTS EASTWARD. ADDITIONAL ENERGY
THEN DIVES ACROSS THE FOUR CORNERS REGION TUESDAY INTO WEDNESDAY.
THIS SECOND ENERGY LOOKS TO REALLY AMPLIFY THE PATTERN WHICH HAS A
LARGE TROUGH IN THE PLAINS THURSDAY THAT PROGRESSES INTO THE
NORTHEAST. THIS SECOND FEATURE MAY BECOME RATHER WRAPPED UP FRIDAY
AND SATURDAY. WE USED MOSTLY A MODEL BLEND APPROACH THROUGH
WEDNESDAY, BUT THEN SWITCHED TO HPC GUIDANCE FROM WEDNESDAY NIGHT
ONWARD. SOME ADDITIONAL TWEAKS WERE DONE BASED ON ADDITIONAL
COLLABORATION WITH OUR NEIGHBORING OFFICES AND ALSO TO MAINTAIN
AT LEAST SOME CONTINUITY.
FOR MONDAY NIGHT AND TUESDAY...AN UPPER-LEVEL TROUGH THAT EVENTUALLY
TAKES ON SOME NEGATIVE TILT WILL PUSH A COLD FRONT ACROSS OUR AREA
LATE MONDAY NIGHT. THE FLOW IS EXPECTED TO BE SOUTHERLY AHEAD OF
THIS FEATURE. THE COMBINATION OF STRONGER WAA AND MOISTURE ADVECTION
WILL RESULT IN ANY LINGERING DRIZZLE/FOG TRANSITIONING TO PERIODS OF
RAIN. A PLUME OF ABOUT 1.0 TO 1.25 INCHES OF PW MOVES THROUGH MONDAY
NIGHT. THIS IN COMBINATION WITH INCREASING LARGE SCALE ASCENT WILL
RESULT IN A PERIOD OF HEAVIER RAIN, WITH THE BULK OF IT FALLING
MONDAY NIGHT. THIS THEN TAPERS OFF DURING TUESDAY MORNING FROM
SOUTHWEST TO NORTHEAST. IF THE SURFACE LOW TRACKING OVER OUR AREA
CAN CONSOLIDATE SOME MORE, THERE MAY BE AN AREA OF MORE FOCUSED
HEAVIER RAINFALL. DESPITE THE RAIN, TEMPERATURES MAY START TO RISE
SOME MONDAY NIGHT. THE MODEL FORECAST SOUNDINGS HINT AT LEAST SOME
ELEVATED INSTABILITY DEVELOPING MONDAY NIGHT, HOWEVER IT MAY NOT BE
ENOUGH TO GET TRUE CHARGE SEPARATION TO OCCUR AND BE LOW-TOPPED. WE
MAINTAINED SOME CONTINUITY AND CARRIED ISOLATED THUNDER ACROSS
PORTIONS OF MARYLAND, DELAWARE AND FAR SOUTHERN NEW JERSEY FOR A
TIME MONDAY NIGHT. OUR POPS PEAK MONDAY NIGHT IN THE CATEGORICAL
RANGE, THEN DECREASE STARTING EARLY TUESDAY MORNING.
AS THE SYSTEM EXITS TO OUR NORTHEAST TUESDAY, THE MODEL CONSENSUS IS
GENERALLY FOR ANY RAIN TO TAPER OFF EARLY IN THE MORNING. HOWEVER AS
THE UPPER-LEVEL TROUGH TAKES ON MORE OF A NEGATIVE TILT, SOME
DEFORMATION TYPE FORCING ON THE WEST SIDE MAY BE STRONG ENOUGH TO
ORGANIZE AN AREA OF WRAPAROUND SHOWERS. THE FORECAST SOUNDINGS
ESPECIALLY ACROSS THE NORTHERN AREAS SUGGEST SOME INSTABILITY
DEVELOPS TUESDAY AFTERNOON AS THE MID LEVEL COLD POOL ARRIVES. THIS
COULD RESULT IN SOME LOW-TOPPED CONVECTIVE SHOWERS WITH PERHAPS
SMALL HAIL OR GRAUPEL. THE SYSTEM THEN CONTINUES TO SHIFT FARTHER
AWAY FROM OUR AREA, THEREFORE POPS LOWER THROUGH TUESDAY NIGHT. THE
COMBINATION OF SOME CAA ALOFT OCCURRING TUESDAY AND A TIGHTENING
PRESSURE GRADIENT SHOULD RESULT IN A DECENT UPTICK IN THE WINDS. THE
BOUNDARY STILL LOOKS MILD WITH THE MAIN COOLING TAKING PLACE ABOVE.
THIS SHOULD RESULT IN BREEZY TO EVEN WINDY CONDITIONS AT TIMES.
FOR WEDNESDAY AND THURSDAY...LOW PRESSURE TRACKS SOUTH OF THE
CANADIAN MARITIMES WITH A CYCLONIC FLOW REGIME OVER OUR REGION TO
START. WHILE THE AIRMASS IS NOT ALL THAT COOLER, FORECAST SOUNDINGS
SHOW ENOUGH OF A GRADIENT FOR BREEZY CONDITIONS DEVELOPING WEDNESDAY
AFTERNOON BEFORE QUICKLY DIMINISHING IN THE EVENING. THE CYCLONIC
FLOW LOOKS TO EASE UP WEDNESDAY NIGHT AND THURSDAY AS RIDGING SLIDES
EASTWARD. THIS WILL RESULT IN LIGHTER WINDS BUT THEN TURNING MORE
SOUTHEASTERLY THURSDAY.
YET ANOTHER STORM IS EXPECTED TO ARRIVE THURSDAY NIGHT AS THIS
ACTIVE PATTERN CONTINUES. THIS SYSTEM IS FORECAST TO BE MUCH MORE
AMPLIFIED AS THE OVERALL SYNOPTIC PATTERN SHIFTS INTO A STRONGER
FLOW. AS A RESULT, CLOUDS ARE EXPECTED TO QUICKLY INCREASE THURSDAY.
INCREASING LARGE SCALE ASCENT ARRIVING FROM THE WEST COMBINED WITH
AMPLE MOISTURE ADVECTION, WAA AND A STRENGTHENING WIND FIELD WILL
RESULT IN AN AREA OF SHOWERS MOVING IN TOWARD THURSDAY EVENING.
WHILE THE PRECIPITATION SHOULD BE CONVECTIVE /SHOWERY/, IT MAY END
UP BEING MORE WIDESPREAD RAIN AS THE SYSTEM PROBABLY OCCLUDES AND A
SURFACE LOW TRIES TO EVENTUALLY DEVELOP ALONG THE TRIPLE POINT.
THERE IS THE POTENTIAL FOR THUNDER AND MORE WIND ASSOCIATED WITH
THIS SYSTEM AS IT IS FORECAST TO BE MORE DYNAMIC. THE SOUTHERLY
WINDS MAY BE GUSTY IN SOME STRONGER CONVECTIVE ELEMENTS DURING THE
EVENING. GIVEN THE ROBUST WARMING OF THE AIRMASS AHEAD OF THE COLD
FRONT, ALL RAIN IS EXPECTED TO OCCUR. GIVEN SOME LINEAR LOOK TO THE
FORCING ALONG WITH A TIGHTENING 850 MB THERMAL GRADIENT MAY ALLOW
FOR THE DEVELOPMENT OF A NARROW COLD FRONTAL RAINBAND.
FOR FRIDAY AND SATURDAY...LOW PRESSURE SHOULD BE RATHER ROBUST FROM
SOUTHEASTERN CANADA AND NEW ENGLAND. A MUCH MORE PRONOUNCED COLDER
AIRMASS LOOKS TO FOLLOW THIS SYSTEM ALONG WITH POTENTIALLY WINDY
CONDITIONS ARRIVING. AS THE PRONOUNCED UPPER-LEVEL TROUGH IS
FORECAST TO BE IN THE EAST, A MUCH STRONGER CAA PATTERN UNDER A
WEST/NORTHWEST FLOW WILL OCCUR ACROSS OUR AREA. DEPENDING ON THE
SYNOPTIC SETUP UP AND DEPTH OF THE COLD AIR, SOME LAKE EFFECT SNOW
MAY RESULT AND MAKE A RUN AT OUR NORTHWEST ZONES. AS OF NOW, WE WENT
WITH SLIGHT CHC TO LOW CHC POPS FRIDAY, THEN DRY SATURDAY OTHER THAN
A MENTION OF FLURRIES ACROSS THE FAR NORTHWEST ZONES.
OF GREATER INTEREST IS THE POTENTIAL FOR STRONG WINDS FRIDAY INTO
SATURDAY. THE STRONG CAA /850 MB TEMPERATURES DOWN TO NEAR -8C/ AND
A TIGHT PRESSURE GRADIENT WILL COMBINE WITH AN 850 MB FLOW OF NEARLY
40-50 KNOTS. THIS COULD RESULT IN SURFACE GUSTS VERY CLOSE TO WIND
ADVISORY CRITERIA WHICH STARTS AT 40 KNOTS /46 MPH/. THERE SHOULD BE
EFFICIENT VERTICAL MIXING ESPECIALLY FRIDAY INTO SATURDAY AS THE
BOUNDARY LAYER COOLS WITH STRONGER CAA ABOVE. SOME SHORT WAVE ENERGY
EMBEDDED IN THE NORTHWESTERLY FLOW MAY RESULT IN A CLIPPER TYPE
SYSTEM THAT DROPS INTO OUR AREA SATURDAY NIGHT WITH ANOTHER COLD
FRONT.
FOR SUNDAY...THE UPPER-LEVEL TROUGH SHOULD BE MAINTAINED ACROSS
EASTERN CANADA AND THE NORTHEAST. THIS SHOULD RESULT IN A COLDER
AIRMASS BEING MAINTAINED ALTHOUGH ALOFT IT LOOKS TO MODIFY SOME
EARLY BEFORE PERHAPS A SECONDARY SURGE ARRIVES IN THE WAKE OF A
CLIPPER OR SECONDARY COLD FRONT. THE OVERALL FLOW STILL LOOKS ACTIVE
AS GUIDANCE SUGGESTS SIGNIFICANT ENERGY ARRIVING ON THE WEST COAST
WITH RIDGING INTO THE PLAINS, AND A TROUGH IN THE NORTHEAST. GIVEN
THIS FLOW REGIME, LAKE EFFECT SNOW MAY STILL BE ONGOING SOME OF
WHICH COULD BE INTO OUR NORTHWEST ZONES. PLENTY OF TIME TO PIN THIS
DOWN AS WIND DIRECTION IS ONE OF THE KEY FACTORS. OVERALL, WE
FOLLOWED HPC GUIDANCE MORE CLOSELY ALTHOUGH DID BUMP UP THE WINDS
SOME AS BRISK CONDITIONS MAY STILL OCCUR.
&&
.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
CONDS CONTINUE TO DETERIORATE ACRS THE AREA WITH MOST LOCATIONS MVFR
OR IFR. AS AN AREA OF LIGHT RAIN MOVED THRU MAINLY ACRS SRN NJ,
VSBYS DROPPED AND THEN CAME BACK UP. HOWEVER, THE OVERALL TREND IS
DOWNWARD, AND MOST LOCATIONS WILL BE IFR THIS EVENING AND EVEN LIFR
OVERNIGHT AS FOG DEVELOPS. CONDS WILL IMPROVE A BIT AFTER DAYBREAK
MONDAY, BUT LOW CLOUDS WILL STILL LINGER AND EXPECT IFR/MVFR FOR THE
BALANCE OF THE DAY. THE WIND IS EXPECTED TO BE VERY LIGHT WITH
SPEEDS GENLY LESS THAN 5 KTS AND IN MANY CASES CALM, WHICH IN THIS
CASE WILL NOT HELP IMPROVE THE VSBY SITUATION.
OUTLOOK...
MONDAY NIGHT...VARIABLE IFR/LIFR IN PERIODS OF RAIN AND LOW
CLOUDS/FOG. WINDS MOSTLY FROM THE SOUTHEAST AT 10 KNOTS OR LESS.
TUESDAY...ANY SUB-VFR CONDITIONS SHOULD IMPROVE TO VFR FROM
SOUTHWEST TO NORTHEAST BY MID-MORNING AS THE RAIN ENDS. WEST TO
NORTHWESTERLY WINDS INCREASE WITH GUSTS TO AROUND 25 KNOTS IN THE
AFTERNOON INTO THE EVENING. SOME WRAPAROUND SHOWERS MAY OCCUR IN THE
AFTERNOON ESPECIALLY NEAR KRDG, KABE TO KTTN.
WEDNESDAY...VFR WITH GUSTY WEST WINDS UP TO 30 KNOTS, DIMINISHING
DURING THE EVENING.
THURSDAY...VFR LOWERING TO SUB-VFR IN SHOWERS. SOUTH-SOUTHEAST WINDS
WITH GUSTS TO AROUND 20 KNOTS. THERE IS A CHANCE OF LOW-LEVEL WIND
SHEAR ESPECIALLY AT NIGHT AS A SOUTHWESTERLY LOW-LEVEL JET INCREASES
TO ABOUT 50 KNOTS NEAR 2,000 FEET.
FRIDAY...A STRONG COLD FRONT SWEEPS THROUGH EARLY WITH SHOWERS
ENDING. WINDS SHIFT TO WESTERLY AND BECOME SUSTAINED AT 15-20 KNOTS
WITH GUSTS TO AROUND 35 KNOTS.
&&
.MARINE...
A SCA HAD BEEN RAISED EARLIER FOR THE NRN WATERS AS SEAS HAD COME UP
TO OVER 6 FT AND THE WIND WAS PUSHING SCA CRITERIA. GUID SHOWED
THAT SEAS SHUD REMAIN ELEVATED THRU THE SHORT TERM PD SO THE SCA
WILL REMAIN UP. FURTHER S, SEAS WILL INCREASE A BIT AS WELL, BUT
ARE EXPECTED TO REMAIN BELOW SCA CRITERIA ATTM.
OUTLOOK...
AN AREA OF LOW PRESSURE AND A COLD FRONT MOVES THROUGH MONDAY NIGHT
WITH A PERIOD OF RAIN. A MILDER AND MOIST AIRMASS IN PLACE AHEAD OF
IT MAY RESULT IN SOME FOG, ALTHOUGH THE RAIN COULD HELP TO AIDE IN
JUST ENOUGH LOW-LEVEL MIXING.
A PERIOD OF SOME CAA OCCURS TUESDAY BEHIND THE SYSTEM, HOWEVER THIS
LOOKS TO BE SHORT IN DURATION. THE MODEL GUIDANCE SHOWS 925 MB WINDS
INCREASE TO ABOUT 30-35 KNOTS AND SOUNDINGS INDICATE THE LOW-LEVEL
LAPSE RATES STEEPEN DURING TUESDAY INTO WEDNESDAY. THIS SHOULD
RESULT IN A STRONG SMALL CRAFT ADVISORY EVENT WITH EVEN A CHANCE FOR
SOME MARGINAL GALE FORCE GUSTS. SINCE THE CAA IS NOT FORECAST TO BE
REAL ROBUST, THE OVERALL MIXING MAY BE JUST ENOUGH TO NOT ALLOW FOR
WIDESPREAD AND MORE PROLONGED GALE GUSTS.
HIGH PRESSURE CENTERED TO OUR SOUTH INFLUENCES OUR WEATHER
WEDNESDAY, THEREFORE THE WINDS ARE EXPECTED TO QUICKLY DIMINISH.
THEREFORE, SUB-SCA CONDITIONS ARE ANTICIPATED WEDNESDAY NIGHT AND
THURSDAY MORNING. A STRENGTHENING SOUTHERLY FLOW /40-55 KNOTS AT
925 MB/ THEN LATER THURSDAY AFTERNOON AND NIGHT AHEAD OF A STRONG
COLD FRONT SHOULD ALLOW WINDS AND SEAS TO EASILY REACH ADVISORY
LEVELS. THERE COULD BE ENOUGH MIXING OCCURRING WITHIN THE WAA REGIME
AND MILDER BOUNDARY LAYER TO GET SOME MARGINAL GALE GUSTS. AS THE
FRONT SWEEPS THROUGH EARLY FRIDAY MORNING, STRONGER CAA KICKS IN
WITH QUICKLY STEEPENING LOW-LEVEL LAPSE RATES. GIVEN THE STRONG CAA
PUSH COMBINED WITH 925 MB WINDS INCREASING TO 35-40 KNOTS FRIDAY
AND FRIDAY NIGHT, SHOULD RESULT IN A GOOD POTENTIAL FOR GALES
OCCURRING. FOR NOW, WE HELD OFF ON ANY HEADLINES FOR MONDAY NIGHT
AND BEYOND HOWEVER A MENTION OF THE POSSIBLE GALES IS IN THE
HAZARDOUS WEATHER OUTLOOK.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST MONDAY FOR ANZ450-451.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...NIERENBERG
SHORT TERM...NIERENBERG
LONG TERM...GORSE
AVIATION...GORSE/NIERENBERG
MARINE...GORSE/NIERENBERG
AREA FORECAST DISCUSSION
NWS DES MOINES IA
307 PM CST SUN DEC 16 2012
.SHORT TERM /TONIGHT/...
CHALLENGING FORECAST ESPECIALLY FROM A FOG AND LOW CLOUDS
PERSPECTIVE. FOG AND LOW CLOUDS HAVE BEEN STUBBORN IN LIFTING TODAY
ESPECIALLY ACROSS THE SOUTHERN...CENTRAL AND EASTERN CWA. AND IN THE
NORTHWESTERN CWA WHERE THE FOG AND LOW CLOUDS DID LIFT...ANOTHER
AREA OF LOW CLOUDS HAS BEEN MOVING SOUTHEAST FROM SOUTH DAKOTA AND
MINNESOTA.
HAVE TAKEN A SOMEWHAT PESSIMISTIC APPROACH TO THE LOW CLOUDS AND FOG
FOR TONIGHT. ALTHOUGH BUFKIT NAM SOUNDINGS ARE OPTIMISTIC...THE
BUFKIT RAP SOUNDINGS ARE QUITE PESSIMISTIC. THE FORECAST TENDS TO
SPLIT THE DIFFERENCE WITH A LEAN TOWARD THE LOW CLOUDS AND FOG BEING
STUBBORN. LOW LEVEL MOISTURE IS EXPECTED TO REMAIN PLENTIFUL
OVERNIGHT ESPECIALLY IN THOSE AREAS THAT STILL HAVE LOW CLOUDS AND
FOG. WITH WIND SPEEDS DECREASING OVERNIGHT...MIXING WILL DIMINISH
AND THE FOG IS EXPECTED TO COME BACK. THUS HAVE GONE WITH PATCHY FOG
WORDING IN MANY AREAS FOR TONIGHT/S FCST GRIDS. IN THE NORTHWESTERN
CWA...HAVE BROUGHT THE CLOUDS BACK IN ALONG WITH THE POSSIBILITY OF
PATCHY FOG THERE AS WELL. THE LOWEST VISIBILITIES IN THE FOG ARE
EXPECTED TO BE IN THE NORTHEASTERN CWA.
ON A DIFFERENT NOTE...SOME WEAK FRONTOGENETICAL FORCING HAS LED TO
AN AREA OF ECHOES ON THE RADAR MAINLY ACROSS THE WESTERN CWA TODAY.
OVER TIME THE ECHOES HAVE SPREAD EASTWARD...INDICATING THAT THE
FORCING IS TRANSLATING EASTWARD...WHICH IS SUPPORTED BY MODEL CROSS
SECTIONS. SINCE THE PRECIP IS NOT EXPECTED TO REACH THE GROUND
MUCH...IF AT ALL...HAVE GONE ONLY WITH SLIGHT CHANCE POPS ACROSS THE
SOUTHERN CWA INTO THIS EVE. THERE IS A DRY ENOUGH LAYER BETWEEN THE
LAYER OF FORCING AND THE LOWER LEVEL MOISTURE THAT THE PRECIP IS NOT
EXPECTED TO MAKE IT THROUGH THAT DRIER LAYER.
.LONG TERM /MONDAY THROUGH SUNDAY/...
A PAIR OF SUCCESSIVE 500 MB SHORTWAVES WILL MOVE ACROSS NORTHERN
IOWA...THE FIRST ON MONDAY AND THE SECOND ON TUESDAY MORNING. AT THE
SURFACE A HIGH PRESSURE RIDGE WILL CROSS THE AREA ON MONDAY...WITH
THE MID-LEVEL SHORTWAVE GENERATING CLOUDS BUT FORECAST SOUNDINGS
INDICATING TOO MUCH DRY AIR IN THE LOWER LEVELS TO RESULT IN
PRECIPITATION. ON MONDAY NIGHT HOWEVER THE RIDGE WILL MOVE OFF TO
THE EAST...AND A SURFACE LOW WILL DEVELOP AROUND THE BLACK HILLS
AHEAD OF THE APPROACHING SECOND WAVE AND MOVE QUICKLY EASTWARD
TOWARD IOWA. THIS WILL CAUSE SURFACE WINDS TO COME AROUND QUICKLY TO
SOUTH BY EARLY TUESDAY MORNING WITH AN INCREASE IN ATMOSPHERIC
MOISTURE. AS THE WAVE AND LOW CROSS THE AREA ON TUESDAY MORNING IT
WILL PROVIDE A BRIEF OPPORTUNITY FOR SOME LIGHT SNOW ACROSS OUR FAR
NORTH BEFORE THE SYSTEM CLEARS OUT RAPIDLY TO THE EAST. AT THIS TIME
WILL STICK WITH JUST SLIGHT POPS ROUGHLY NORTH OF HIGHWAY 20 ON
TUESDAY MORNING...AND LITTLE IF ANY ACCUMULATION IS ANTICIPATED.
THE BIGGEST POTENTIAL WEATHER IMPACT OF THE SEVEN DAY FORECAST WILL
COME FROM A LONGWAVE 500 MB TROUGH COMING ASHORE OVER THE PACIFIC
U.S. COAST LATE ON TUESDAY. IT STILL APPEARS THAT THIS TROUGH WILL
NOT BE FULLY PHASED...AND THAT MOST OF THE ENERGY WILL DIG INTO THE
SOUTHERN STREAM WITH A NORTHERN STREAM WAVE TRAILING SLIGHTLY
BEHIND. AS THE OVERALL SYSTEM MOVES EASTWARD TOWARD THE CENTRAL U.S.
AND IOWA THE COMPLICATED EVOLUTION OF THE TWO INTERTWINED WAVES WILL
HAVE DRAMATIC IMPACTS ON THE DETAILS OF THEIR ASSOCIATED SENSIBLE
WEATHER. THE SOUTHERN STREAM WAVE WILL GENERATE A STRONG SURFACE LOW
PRESSURE CENTER OVER THE SOUTHERN HIGH PLAINS ON TUESDAY NIGHT/EARLY
WEDNESDAY...WHICH WILL SUBSEQUENTLY MOVE EAST NORTHEAST ACROSS
MISSOURI AND ILLINOIS...WITH A LARGE SWATH OF SNOW SPREADING ALONG
THE NORTHWESTERN FLANK OF THE TRACK. HOWEVER THE PHASING
ISSUES...COMBINED WITH THE FACT THAT THE ENTIRE SYSTEM IS STILL WELL
OFFSHORE AND NOT BEING SAMPLED BY THE UPPER AIR NETWORK...ARE
WREAKING HAVOC WITH THE FORECAST OF THE STORM TRACK BEING OUTPUT BY
THE VARIOUS PROGNOSTIC MODELS. A SHIFT OF 50 OR 100 MILES ONE WAY OR
ANOTHER WILL MAKE THE DIFFERENCE BETWEEN THE HEAVIER SNOW SWATH
FALLING ACROSS CENTRAL IOWA...SOUTHEASTERN IOWA...OR NORTHEASTERN
MISSOURI. GIVEN THE INHERENT UNCERTAINTY IN THIS SCENARIO AND POOR
CONSISTENCY AMONG THE MODELS HAVE OPTED TO KEEP THE FORECAST VERY
CLOSE TO PREVIOUS ISSUANCES...WITH LIKELY TO CATEGORICAL POPS ACROSS
ABOUT THE SOUTHEASTERN HALF OR TWO THIRDS OF THE CWA. IT IS STILL
TOO EARLY TO MAKE ANY FORECAST OF SNOWFALL AMOUNTS...BUT SEVERAL
INCHES OF SNOWFALL ARE LIKELY TO THE NORTHWEST OF THE LOW AND
PROBABLY SOMEWHERE IN THE SOUTHEASTERN HALF OF OUR AREA. THIS WILL
BE CLOSELY MONITORED OVER THE NEXT SEVERAL DAYS.
THE MIDWEEK SYSTEM WILL CLEAR OUT QUICKLY LATE THURSDAY AND THURSDAY
NIGHT...AFTER WHICH QUIET AND DRY WEST NORTHWESTERLY 500 MB FLOW
WILL BE ESTABLISHED. THIS WILL LEAD TO COOLER WEATHER...ESPECIALLY
IF A SNOW PACK IS IN PLACE AFTER THE WEDNESDAY/THURSDAY STORM...WITH
NO ADDITIONAL PRECIPITATION IN THE FORECAST.
&&
.AVIATION...16/18Z
LOW CONFIDENCE FCST AT ALL TERMINALS DUE MAINLY TO STUBBORN FOG AND
STRATUS. SOME FCST GUIDANCE IS OPTIMISTIC AT THE FOG AND STRATUS
LIFTING THIS AFTN/EVENING...WHILE OTHER GUIDANCE KEEPS IT AROUND
LONGER AND BRINGS IT BACK TONIGHT. FOR NOW HAVE GONE MIDDLE OF THE
ROAD AT ALL TERMINALS...AND WILL MONITOR WX TRENDS FOR UPDATES.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...ZOGG
LONG TERM...LEE
AVIATION...ZOGG
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1151 AM CST SUN DEC 16 2012
...UPDATE TO AVIATION...
.UPDATE...
AFTER MAKING SOME CALLS ACROSS EAST CENTRAL KS...IT APPEARS AS
THOUGH THE HIGH CLOUDS HAVE NOT DIMINISHED THE DENSE FOG. NOW THAT
SKIES ARE CLEARING OUT AGAIN...VISIBILITIES ARE LIKELY TO REMAIN
DOWN TO A QUARTER OF A MILE...AND WE HAVE ISSUED A DENSE FOG
ADVISORY THROUGH MID MORNING.
&&
.DISCUSSION...
09Z WATER VAPOR IMAGERY SHOWS A COMPACT SHORTWAVE OVER THE NM/CO
ROCKIES. A SECOND SHORTWAVE WAS NOTED OVER THE PACIFIC NORTHWEST. AT
THE SURFACE...WEAK RIDGING WAS SEEN FROM THE NORTHERN PLAINS INTO
NORTHERN KS.
FOR TODAY THROUGH MONDAY...A RATHER DISORGANIZED CYCLONIC FLOW IS
PROGGED TO AFFECT THE AREA WITH THE SHORTWAVES NOTED ON WATER VAPOR
TRAVERSING THE AREA. INITIALLY FORECAST SOUNDINGS FROM THE RAP AND
NAM SHOW SOME MID LEVEL DRY AIR THAT HAS TO BE OVERCOME WITH THE
BETTER MID LEVEL SATURATION REMAINING JUST NORTH OF THE STATE LINE.
WITH THIS IN MIND AND THE MODELS SHOWING THE SHORTWAVE OVER NM/CO
WEAKENING AS IT MOVES EAST...WILL MAINTAIN THE MENTION OF FLURRIES
AND OR SPRINKLES ACROSS THE FAR NORTHERN COUNTIES THINKING THAT ANY
PRECIP WILL NOT BE MEASURABLE. IT SEEMS THAT DRY LOW LEVELS FOR
TONIGHT AND MONDAY MORNING WILL ALSO LIMIT PRECIP CHANCES AS THE
WAVE OVER THE PACIFIC NORTHWEST KICKS THE LONGWAVE TROUGH EAST. WITH
WEAK COLD AIR ADVECTION AND INCREASING CLOUDS...TEMPS SHOULD BE
COOLER TODAY WITH HIGHS GENERALLY IN THE 40S. LOW LEVEL WINDS ARE
EXPECTED TO TURN BACK FROM THE SOUTH AND SOUTHWEST FOR MONDAY...SO
TEMPS SHOULD BEGIN TO MODERATE.
THE NEXT CHANCE FOR MEASURABLE PRECIP CONTINUES TO LOOK LIKE IT WILL
OCCUR WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT...AND WE MAY END UP
SEEING THE FIRST SNOWFALL OF THE WINTER. THE GFS AND ECMWF APPEAR TO
BE CONVERGING ON A PROGRESSIVE SYSTEM MOVING ACROSS THE PLAINS AS
THE NEXT SHORTWAVE TROUGH PROPAGATES ACROSS NORTH AMERICA. WHILE THE
GFS IS NOTABLY FASTER WITH THE SURFACE LOW...THE TRACKS OF THE
SYSTEM ARE SIMILAR FROM BOTH MODEL SOLUTIONS. ALSO BECAUSE OF THE
PROGRESSIVE NATURE OF THE SYSTEM AND BOTH MODELS DEEPENING THE
SURFACE LOW AS IT PASSES SOUTHEAST OF THE FORECAST AREA...THE COLD
AIR IS QUICKER TO PUSH SOUTH DURING THE AFTERNOON WEDNESDAY WITH
TEMPS POTENTIALLY FALLING DURING THE AFTERNOON. THERE APPEARS TO BE
DECENT QG VECTOR CONVERGENCE WITH THE SYSTEM AND MODELS SHOW GOOD
MID LEVEL FRONTOGENESIS NORTHWEST OF THE SURFACE LOW TRACK. GIVEN
THE TEMP PROFILES RAPIDLY COOLING AND THE MESOSCALE FORCING...THINK
THERE COULD BE A BAND OF SNOW FORM LATE WEDNESDAY AFTERNOON AND
THROUGH THE NIGHT. CROSS SECTIONS FROM THE GFS AND ECMWF SUGGEST THE
STRONGER VERTICAL MOTION WILL OCCUR BETWEEN 00 AND 06Z THUR WITH DRY
AIR AND SUBSIDENCE QUICKLY FILLING IN TOWARDS 12Z. BECAUSE OF THE
PROGRESSIVE NATURE OF THE SYSTEM...SNOW AMOUNTS LOOK TO BE ON THE
ORDER OF A COUPLE INCHES.
SOMEWHAT ZONAL FLOW DEVELOPS IN THE WAKE OF THE WEDNESDAY NIGHT
SYSTEM...WITH THE UPPER LEVEL JET SETTING UP ACROSS THE SOUTHERN
HALF OF THE COUNTRY. THIS SHOULD KEEP A DRY AND COOL AIRMASS OVER
THE PLAINS FOR THURSDAY NIGHT THROUGH SATURDAY.
WOLTERS
&&
.AVIATION...
MAIN CONCERN WILL BE HOW LONG IFR/LIFR CONDITIONS PERSIST ACROSS THE
TAF SITES. DAY TIME HEATING SHOULD INCREASE TEMPERATURES ENOUGH TO
IMPROVE THE VSBY TO MVFR THIS AFTERNOON AROUND 20Z. THE CEILINGS
SHOULD ALSO IMPROVE TO MVFR SOMETIME THIS EVENING WHICH WILL
REMAIN ENTRENCHED ACROSS THE TAF SITES THROUGH TONIGHT. DEPENDING
ON WHEN THE STRATUS CLEARS OUT FOG MAY DEVELOP AGAIN TONIGHT BUT
WILL LET LATER SHIFTS MONITOR THE SITUATION.
SANDERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1146 AM CST SUN DEC 16 2012
...UPDATED AVIATION SECTION FOR 18Z TAFS...
.UPDATE...
ISSUED AT 944 AM CST SUN DEC 16 2012
THE DENSE FOG ADVISORY WAS UPDATED TO REFLECT THE SOUTHWEST
ADVECTION OF THE FOG DOWN INTO THE LIBERAL AND MEADE AREAS. HRRR
AND RAP MODELS SUGGEST VISIBLITIES WILL STAY DOWN UNTIL AROUND
17Z...WITH ONLY SLOW IMPROVEMENT IN VISIBILITY AND CEILING THROUGH
MIDDAY/EARLY AFTERNOON. THIS WILL IMPACT TEMPERATURES TODAY AND
HAVE HAD TO DRASTICALLY LOWER THE TEMPERATURES FOR TODAY FROM THE
ARKANSAS RIVER SOUTH TO THE OKLAHOMA BORDER AS MESOSCALE LOW WILL
TRAVEL ALONG THE KS-OK BORDER TODAY KEEPING COOL, MOIST NORTHEAST
WINDS IN PLACE PRETTY MUCH ALL DAY.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 341 AM CST SUN DEC 16 2012
THE COLORADO SHORTWAVE HAS BEEN PROGRESSING STEADILY EASTWARD PER
SATELLITE LOOPS. EXTRAPOLATING IT AT ITS CURRENT SPEED WOULD PUT IT
OVER SOUTH CENTRAL KANSAS BY 18Z. THE 00Z NAM HAS A PRETTY GOOD
HANDLE ON THIS. THIS MODEL ALSO KEEPS ANY PRECIPITATION ASSOCIATED
WITH THIS WAVE OVER FAR NORTHERN KANSAS THIS MORNING. THE LATEST
RUNS OF THE RUC13 ARE ALSO DRY BUT IT DOES TRY TO DEVELOP SOME
LIGHT PRECIPITATION OVER SOUTH CENTRAL KANSAS TOWARD MIDDAY. BASED
ON CURRENT RADAR TRENDS, HAVE OPTED TO LOWER POPS ACROSS WEST
CENTRAL KANSAS THIS MORNING AND REMOVE THE MENTION OF SPRINKLES
FROM THE FORECAST. THIS WILL HAVE TO BE WATCHED FOR THE NEXT FEW
HOURS FOR ANY CHANGES IN THE CURRENT RADAR TRENDS.
ONCE THE FIRST WAVE MOVES OUT OF WESTERN KANSAS, WE SHOULD SEE AN
INCREASE IN SUNSHINE FOR A WHILE UNTIL CIRRUS ASSOCIATED WITH THE
NEXT WAVE BEGINS TO MOVE IN FROM THE WEST. THIS COULD HELP BOOST
TEMPERATURES UP A LITTLE THIS AFTERNOON AND HAVE ADJUSTED TODAY`S
HIGH TEMPERATURES UP A BIT ESPECIALLY OVER CENTRAL KANSAS.
THE NEXT WAVE WILL MOVE OUT OVER THE CENTRAL HIGH PLAINS THIS
EVENING AND SHOULD BE EAST OF THE AREA BY MIDNIGHT. AM NOT
EXPECTING ANY SIGNIFICANT PRECIPITATION WITH THIS WAVE AS WELL.
HAVE LOWERED SUNDAY NIGHTS LOW TEMPERATURES A FEW DEGREES CLOSER
TO THE NAM MOS NUMBERS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 403 AM CST SUN DEC 16 2012
THE MAJOR ADJUSTMENTS TO THE EXTENDED FORECAST OCCURRED IN THE
WEDNESDAY AND WEDNESDAY NIGHT TIMEFRAME, WHEN THE POTENTIAL FOR A
DYNAMIC LOW TO DEVELOP OVER THE HIGH PLAINS, BRINGING GOOD POTENTIAL
FOR WINDY AND SNOWY CONDITIONS.
THE RELATIVELY MILD TEMPERATURES WILL CONTINUE ON MONDAY AND
TUESDAY, AS A FAST MOVING PACIFIC JET SPREADS INTO THE NATIONS
INTERIOR, FORMING A PROGRESSIVE FLAT RIDGE THAT LIFTS INTO THE
EASTERN HALF OF THE NATION BY WEDNESDAY. THE POSITION OF THE JET AND
THE RELATIVE HUMIDITY FIELDS OF MODEL LOWER AND MID TROPOSPHERIC
LAYERS SUGGEST MOSTLY SUNNY CONDITIONS SHOULD BE EXPERIENCED ACROSS
WESTERN KANSAS MONDAY AND TUESDAY. EARLY IN THE PERIOD LIGHT NORTHERLY
WINDS ASSOCIATED WITH THE RETREATING NORTHERN PLAINS HIGH WILL
BECOME MORE SOUTHWESTERLY BY TUESDAY AS SURFACE TROUGHING DEVELOPS
ACROSS THE DAKOTAS. MODEL CONSENSUS CONTINUES TO SUPPORT HIGHS
REACHING THE 50S. TUESDAY MAY BE AROUND 5 DEGREES WARMER WITH
TEMPERATURES REACHING AROUND 60 DEGREES WITH WEAK DOWNSLOPING
SURFACE WINDS, ESPECIALLY ACROSS SOUTH CENTRAL KANSAS.
THE UPPER FLOW WILL BE RAPIDLY DEVELOPING INTO A STRONGLY AMPLIFIED
UPPER TROUGH EARLY WEDNESDAY, AND DRIVE A COLD FRONT THROUGH WESTERN
KANSAS WEDNESDAY MORNING. BOTH THE ECMWF AND GFS DEVELOP A SURFACE
TO 700 LOW POLEWARD TILTED FROM NORTHERN OKLAHOMA INTO KANSAS. THIS
SHOULD PRODUCE A PERIOD OF MID LEVEL FRONTOGENETIC FORCING WITH COLD
ENOUGH AIR FOR SNOW ACCUMULATION TO DEVELOP BEHIND THE SURFACE COLD
FRONT. THE INTENSITY AND LOCATIONS ARE HOWEVER STILL MUCH OF AN
UNCERTAINTY AT THIS TIME. REGARDLESS, WE`VE INCREASED POPS IN THE
WEDNESDAY TIMEFRAME AND FOLLOWED THE COLDER MODEL TRENDS FOR
TEMPERATURES INTO THURSDAY AND THURSDAY NIGHT. WE USED A SLIGHTLY
DOWNWARD ADJUSTED ECMWF QPF FORECAST. BASED ON TEMPERATURES NOT
EXPECTED TO BE EXCEEDING COLD WEDNESDAY, AND WINDY CONDITIONS BEHIND
THE BOUNDARY, A CONSERVATIVE 8:1 SNOW RATIO WAS USED FOR THE SNOW
ACCUMULATION. THAT PRODUCES SNOWFALL AMOUNTS RANGING FROM AROUND A
HALF INCH TO AN INCH AN A HALF. ADDITIONAL MODEL RUNS MAY SHED MORE
INSIGHT ON WHETHER SIGNIFICANT IMPACTS MAY OCCUR, BUT WITH THESE
KIND OF SNOW TOTALS AND WIND SPEEDS, HEADLINES DON`T APPEAR LIKELY
AT THIS TIME.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1145 AM CST SUN DEC 16 2012
THE REMAINDER OF THE AFTERNOON WILL SEE VFR CONDITIONS AFTER THE
MORNING DENSE FOG EVENT. SURFACE WINDS NORTHWEST OF THE DEPARTING
SMALL SCALE LOW WILL REMAIN LIGHT, MAINLY OUT OF THE
NORTH/NORTHEAST, AND RESIDUAL MOISTURE WILL HANG AROUND THIS
EVENING, PARTICULARLY AT DDC. DRY AIR ADVECTION WILL INCREASE LATE
TONIGHT ACROSS THE WEST. WILL CARRY 3 MILES VISIBILITY IN THE
FORECAST FOR DDC TERMINAL 06-12Z MONDAY MORNING BUT KEEP VFR
CONDITIONS THROUGHOUT AT GCK AND HYS. A REPEAT OF THE DENSE FOG
EVENT TOMORROW MORNING IS UNLIKELY WITH AFOREMENTIONED DOWNSLOPE
FLOW INCREASING BY DAYBREAK MONDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 42 24 54 29 / 10 10 0 0
GCK 44 22 52 28 / 10 10 0 0
EHA 43 25 54 31 / 10 0 0 0
LBL 39 22 54 29 / 10 10 0 0
HYS 44 24 52 28 / 10 10 0 0
P28 43 29 57 30 / 10 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...UMSCHEID
SHORT TERM...GERARD
LONG TERM...RUSSELL
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
324 PM EST SUN DEC 16 2012
.SYNOPSIS...
LOW PRESSURE DRIFTING EASTWARD ACROSS THE GREAT LAKES WILL PROVIDE
THE UPPER OHIO VALLEY WITH MILD CLOUDY CONDITIONS AND ISOLATED
LIGHT SHOWERS INTO MONDAY MORNING. THEN LOW PRESSURE FORMING NEAR
ARKANSAS TONIGHT WILL MOVE NORTHEASTWARD WITH MORE NUMEROUS
SHOWERS LATER MONDAY INTO MIDDAY TUESDAY. A STRONG COLD FRONT LATE
THURSDAY WILL BRING NOTICEABLY COLDER TEMPERATURES FOR THE
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
BLEND OF RECENT SURFACE SATELLITE AND RADAR DATA COUPLED WITH
RECENT RAP WRF-NMM AND SREF MODEL OUTPUT SHOW CLOUDY MILD
CONDITIONS CONTINUING ACROSS THE UPPER OHIO VALLEY WITH NO MORE
THAN ISOLATED LIGHT SHOWERS INTO EARLY TONIGHT.
MODELS CONTINUE TO SUGGEST THERE CAN BE AN INCREASE IN SHOWER
CHANCES SOUTH OF THE I-70 CORRIDOR LATE TONIGHT. LIFT MAY BECOME
MORE ORGANIZED JUST SOUTH OF THE OHIO RIVER...DUE TO INCREASED
CONVERGENCE ASSOCIATED WITH AN INCREASED LOW LEVEL JET DEVELOPING
AHEAD OF THE LOW PRESSURE CENTER DEVELOPING NEAR ARKANSAS.
FORECASTED TEMPERATURES TO REMAIN MILD THROUGH TONIGHT WITH
MINIMAL NIGHTTIME COOLING...SO THIS HIGHS THIS AFTERNOON AND
LOWS TONIGHT CAN BE MORE THAN 20 DEGREES WARMER THAN NORMAL.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
RECENT SREF MODEL OUTPUT...WITH DETAILS FROM NAM GFS AND WRF-
NMM...SHOW SHOWERS...ASSOCIATED WITH LOW PRESSURE CENTER TRACKING
NORTHEASTWARD ALONG THE APPALACHIAN MOUNTAINS...SPREADING SOUTH TO
NORTH ACROSS THE UPPER OHIO VALLEY MONDAY AND MONDAY NIGHT.
SHOWERS WILL EXIT EAST AS THE LOW PRESSURE CENTER EXITS PAST NEW
ENGLAND TUESDAY AFTERNOON.
ENSUING COLD POOL IS NOT THAT COLD OR DEEP...SO INSTABILITY
FOR SHOWERS WILL LIKEWISE BE WEAK. SO IT APPEARS LIKELY THAT MOST
POST SYSTEM SHOWERS WILL HAVE ENDED FOR MOST LOCATIONS BEFORE ANY
CHANGE OVER TO LIGHT OR WET SNOW OCCURS LATE TUESDAY AFTERNOON.
CONSENSUS OF GFS AND NAM MOS PLUS SREF MEAN VALUES SHOW TEMPERATURES
COOLING WITH THE SHOWERS AND LOW PRESSURE PASSAGE MONDAY NIGHT AND
TUESDAY...BUT STILL BE GENERALLY UP TO 10 DEGREES WARMER THAN NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
WEAK HIGH PRESSURE RIDGE WILL BUILD IN TUESDAY NIGHT BEHIND
DEPARTING LOW PRESSURE. THINK THAT SHOWERS WILL DISSIPATE QUICKLY
TUESDAY EVENING AS INVERSION HEIGHTS FALL RAPIDLY. SKIES WILL REMAIN
AT LEAST PARTLY CLOUDY THROUGH MUCH OF TUESDAY NIGHT AND
WEDNESDAY...ALTHOUGH FLOW WILL INCLUDE A SOUTHERLY COMPONENT AND NOT
ALLOW FOR LAKE EFFECT.
MODELS ARE THEN IN GENERAL AGREEMENT ABOUT LOW PRESSURE MOVING
NORTHEAST ACROSS THE CENTRAL PLAINS INTO ONTARIO BY FRIDAY MORNING.
SLIGHTLY INCREASED THE LIKELY POPS THAT WERE ALREADY IN THE FORECAST
WITH SOLID CONSENSUS FROM DETERMINISTIC/ENSEMBLE MODELS.
TEMPERATURES WILL SURGE INTO THE LOWER 50S AHEAD OF THE FRONT ON
THURSDAY...WITH A STRONG DROPOFF AS THE FRONT MOVES THROUGH. IN
FACT...HIGHS ON FRIDAY MAY ONLY BE A COUPLE DEGREES HIGHER THAN
THURSDAY NIGHT LOWS. ALL PRECIPITATION SHOULD CHANGE OVER FROM RAIN
TO SNOW AFTER MIDNIGHT ON THURSDAY...WITH LAKE EFFECT MACHINE
STARTING UP AT THAT TIME.
ANOTHER CONCERN ON FRIDAY WILL BE WIND GUSTS...WITH LAST 2 GFS RUNS
SHOWING 40-45 KT POTENTIAL WIND GUSTS IN BUFKIT AND CIPS ANALOG
GUIDANCE SUGGESTING THAT ABOUT HALF OF PREVIOUS CLIMATOLOGY EVENTS
HAD WIND GUSTS OVER 40 KTS. 12Z GFS/ECMWF SHOW SOME DISAGREEMENT AS
TO HOW LONG LAKE EFFECT WILL PERSIST...BUT DECIDED TO KEEP AT LEAST
SLIGHT CHANCE POPS UP NORTH THROUGH THE REST OF THE FORECAST.
TEMPERATURES WILL STRUGGLE TO CLIMB ABOVE FREEZING FRIDAY THROUGH
SUNDAY.
&&
.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
RECENT SURFACE AND SATELLITE DATA SHOW STRATOCUMULUS CEILINGS
ACROSS THE UPPER OHIO VALLEY WILL BE MAINLY MVFR INTO TONIGHT.
ANY SHOWERS WILL BE ISOLATED IN COVERAGE AND LIGHT IN INTENSITY
AND SHOULD NOT ADD TO ANY RESTRICTIONS.
AS LOW PRESSURE CENTER FROM ARKANSAS MOVES NORTHEASTWARD ALONG THE
APPALACHIAN MOUNTAINS MONDAY...SHOWERS AND RESTRICTIONS WILL
LIKEWISE SPREAD SOUTH TO NORTH ACROSS THE UPPER OHIO VALLEY
DAYTIME MONDAY. AT THIS JUNCTURE HAVE NOT FORECASTED LOWER THAN
MVFR...BUT IFR CANNOT BE RULED OUT BY LATE MONDAY AFTERNOON.
SURFACE WINDS WILL BE FROM THE SOUTH AND SOUTHEAST AT 5 TO 15 KTS
INTO MONDAY.
.OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/...
IFR RESTRICTIONS CAN OCCUR MONDAY NIGHT INTO TUESDAY MORNING DUE
TO SHOWERS WITH NORTHEASTWARD PASSAGE OF LOW PRESSURE CENTER. SOME
MVFR RESTRICTIONS MAY REMAIN TUESDAY AFTERNOON INTO WEDNESDAY DUE
TO LINGERING POST SYSTEM COLD POOL STRATOCUMULUS. ANOTHER LOW
PRESSURE SYSTEM WILL BRING SHOWERS AND RESTRICTIONS THURSDAY INTO
FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
225 PM EST SUN DEC 16 2012
.SYNOPSIS...
LOW PRESSURE DRIFTING EASTWARD ACROSS THE GREAT LAKES WILL PROVIDE
THE UPPER OHIO VALLEY WITH MILD CLOUDY CONDITIONS AND ISOLATED
LIGHT SHOWERS INTO MONDAY MORNING. THEN LOW PRESSURE FORMING NEAR
ARKANSAS TONIGHT WILL MOVE NORTHEASTWARD WITH MORE NUMEROUS
SHOWERS LATER MONDAY INTO MIDDAY TUESDAY. A STRONG COLD FRONT LATE
THURSDAY WILL BRING NOTICEABLY COLDER TEMPERATURES FOR THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
BLEND OF RECENT SURFACE SATELLITE AND RADAR DATA COUPLED WITH
RECENT RAP WRF-NMM AND SREF MODEL OUTPUT SHOW CLOUDY MILD
CONDITIONS CONTINUING ACROSS THE UPPER OHIO VALLEY WITH NO MORE
THAN ISOLATED LIGHT SHOWERS INTO EARLY TONIGHT.
MODELS CONTINUE TO SUGGEST THERE CAN BE AN INCREASE IN SHOWER
CHANCES SOUTH OF THE I-70 CORRIDOR LATE TONIGHT. LIFT MAY BECOME
MORE ORGANIZED JUST SOUTH OF THE OHIO RIVER...DUE TO INCREASED
CONVERGENCE ASSOCIATED WITH AN INCREASED LOW LEVEL JET DEVELOPING
AHEAD OF THE LOW PRESSURE CENTER DEVELOPING NEAR ARKANSAS.
FORECASTED TEMPERATURES TO REMAIN MILD THROUGH TONIGHT WITH
MINIMAL NIGHTTIME COOLING...SO THIS HIGHS THIS AFTERNOON AND
LOWS TONIGHT CAN BE MORE THAN 20 DEGREES WARMER THAN NORMAL.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
RECENT SREF MODEL OUTPUT...WITH DETAILS FROM NAM GFS AND WRF-
NMM...SHOW SHOWERS...ASSOCIATED WITH LOW PRESSURE CENTER TRACKING
NORTHEASTWARD ALONG THE APPALACHIAN MOUNTAINS...SPREADING SOUTH TO
NORTH ACROSS THE UPPER OHIO VALLEY MONDAY AND MONDAY NIGHT.
SHOWERS WILL EXIT EAST AS THE LOW PRESSURE CENTER EXITS PAST NEW
ENGLAND TUESDAY AFTERNOON.
ENSUING COLD POOL IS NOT THAT COLD OR DEEP...SO INSTABILITY
FOR SHOWERS WILL LIKEWISE BE WEAK. SO IT APPEARS LIKELY THAT MOST
POST SYSTEM SHOWERS WILL HAVE ENDED FOR MOST LOCATIONS BEFORE ANY
CHANGE OVER TO LIGHT OR WET SNOW OCCURS LATE TUESDAY AFTERNOON.
CONSENSUS OF GFS AND NAM MOS PLUS SREF MEAN VALUES SHOW TEMPERATURES
COOLING WITH THE SHOWERS AND LOW PRESSURE PASSAGE MONDAY NIGHT AND
TUESDAY...BUT STILL BE GENERALLY UP TO 10 DEGREES WARMER THAN NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
HIGH PRES RIDGING WL BUILD IN WED...WITH WAA KICKING IN AS THE
RIDGE AXIS PASSES EAST. MODELS WERE TRENDING MUCH WARMER WED AND
WED NT THAN EARLIER...SO INCREASED TEMPS DURING DURING THAT TIME.
NO OTHER MAJOR CHANGES TO THE LONG TERM PERIOD WERE MADE.
PREVIOUS...
THE NEXT STORM SYSTEM WILL DEVELOP IN THE PLAINS AND
BEGIN TO AFFECT THE REGION THURSDAY. WITH GOOD AGREEMENT FROM 12Z
GFS/ECMWF AND 00Z NAEFS...HAVE BUMPED UP POPS TO LIKELY THURSDAY
AFTERNOON AND EVENING AS BULK OF PRECIPITATION WILL COME THROUGH
WITH COLD FRONT.
LOW CENTER WILL THEN MEANDER ACROSS THE EASTERN GREAT LAKES ON
FRIDAY. THE LOW WILL PUMP COLD AIR INTO THE AREA ON FRIDAY...AND
TEMPERATURES MAY DECREASE THROUGHOUT THE ENTIRE DAY. COLD AIR AND
ADDITIONAL MOISTURE WILL ALLOW FOR A GOOD CHANCE OF LAKE
EFFECT/UPSLOPE SNOW SHOWERS FRIDAY AND SATURDAY.
ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY WILL TUMBLE
BELOW NORMAL FOR FRIDAY AND SATURDAY BEHIND THE COLD FRONT.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
RECENT SURFACE AND SATELLITE DATA SHOW STRATOCUMULUS CEILINGS
ACROSS THE UPPER OHIO VALLEY WILL BE MAINLY MVFR INTO TONIGHT.
ANY SHOWERS WILL BE ISOLATED IN COVERAGE AND LIGHT IN INTENSITY
AND SHOULD NOT ADD TO ANY RESTRICTIONS.
AS LOW PRESSURE CENTER FROM ARKANSAS MOVES NORTHEASTWARD ALONG THE
APPALACHIAN MOUNTAINS MONDAY...SHOWERS AND RESTRICTIONS WILL
LIKEWISE SPREAD SOUTH TO NORTH ACROSS THE UPPER OHIO VALLEY
DAYTIME MONDAY. AT THIS JUNCTURE HAVE NOT FORECASTED LOWER THAN
MVFR...BUT IFR CANNOT BE RULED OUT BY LATE MONDAY AFTERNOON.
SURFACE WINDS WILL BE FROM THE SOUTH AND SOUTHEAST AT 5 TO 15 KTS
INTO MONDAY.
.OUTLOOK.../MONDAY THROUGH FRIDAY/...
IFR RESTRICTIONS CAN OCCUR MONDAY NIGHT INTO TUESDAY MORNING DUE
TO SHOWERS WITH NORTHEASTWARD PASSAGE OF LOW PRESSURE CENTER. SOME
MVFR RESTRICTIONS MAY REMAIN TUESDAY AFTERNOON INTO WEDNESDAY DUE
TO LINGERING POST SYSTEM COLD POOL STRATOCUMULUS. ANOTHER LOW
PRESSURE SYSTEM WILL BRING SHOWERS AND RESTRICTIONS THURSDAY INTO
FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
123 PM EST SUN DEC 16 2012
.SYNOPSIS...
LOW PRESSURE DRIFTING EASTWARD ACROSS THE GREAT LAKES WILL PROVIDE
THE UPPER OHIO VALLEY WITH MILD CLOUDY CONDITIONS AND ISOLATED
LIGHT SHOWERS INTO MONDAY MORNING. THEN LOW PRESSURE FORMING NEAR
ARKANSAS TONIGHT WILL MOVE NORTHEASTWARD WITH MORE NUMEROUS
SHOWERS LATER MONDAY INTO MIDDAY TUESDAY. A STRONG COLD FRONT LATE
THURSDAY WILL BRING NOTICEABLY COLDER TEMPERATURES FOR THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
BLEND OF RECENT SURFACE SATELLITE AND RADAR DATA COUPLED WITH
RECENT RAP WRF-NMM AND SREF MODEL OUTPUT SHOW CLOUDY MILD
CONDITIONS CONTINUING ACROSS THE UPPER OHIO VALLEY WITH NO MORE
THAN ISOLATED LIGHT SHOWERS INTO EARLY TONIGHT.
MODELS CONTINUE TO SUGGEST THERE CAN BE AN INCREASE IN SHOWER
CHANCES SOUTH OF THE I-70 CORRIDOR LATE TONIGHT...AS LIFT MAY
BECOME MORE ORGANIZED ALONG AN INCREASED LOW LEVEL JET AHEAD OF
THE LOW PRESSURE CENTER DEVELOPING NEAR ARKANSAS.
FORECASTED TEMPERATURES TO REMAIN MILD THROUGH TONIGHT WITH
MINIMAL NIGHTTIME COOLING...SO THIS HIGHS THIS AFTERNOON AND
LOWS TONIGHT CAN BE MORE THAN 20 DEGREES WARMER THAN NORMAL.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
RECENT SREF MODEL OUTPUT...WITH DETAILS FROM NAM GFS AND WRF-
NMM...SHOW SHOWERS...ASSOCIATED WITH LOW PRESSURE CENTER TRACKING
NORTHEASTWARD ALONG THE APPALACHIAN MOUNTAINS...SPREADING SOUTH TO
NORTH ACROSS THE UPPER OHIO VALLEY MONDAY AND MONDAY NIGHT.
SHOWERS WILL EXIT EAST AS THE LOW PRESSURE CENTER EXITS PAST NEW
ENGLAND TUESDAY AFTERNOON.
ENSUING COLD POOL IS NOT THAT COLD OR DEEP...SO INSTABILITY
FOR SHOWERS WILL LIKEWISE BE WEAK. SO IT APPEARS LIKELY SHOWERS
WILL HAVE ENDED FOR MOST LOCATIONS BEFORE ANY CHANGE TO SNOW
OCCURS LATE TUESDAY AFTERNOON.
CONSENSUS OF GFS AND NAM MOS PLUS SREF MEAN VALUES SHOW TEMPERATURES
COOLING WITH THE SHOWERS AND LOW PRESSURE PASSAGE...BUT STILL BE
GENERALLY UP TO 10 DEGREES WARMER THAN NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
HIGH PRES RIDGING WL BUILD IN WED...WITH WAA KICKING IN AS THE
RIDGE AXIS PASSES EAST. MODELS WERE TRENDING MUCH WARMER WED AND
WED NT THAN EARLIER...SO INCREASED TEMPS DURING DURING THAT TIME.
NO OTHER MAJOR CHANGES TO THE LONG TERM PERIOD WERE MADE.
PREVIOUS...
THE NEXT STORM SYSTEM WILL DEVELOP IN THE PLAINS AND
BEGIN TO AFFECT THE REGION THURSDAY. WITH GOOD AGREEMENT FROM 12Z
GFS/ECMWF AND 00Z NAEFS...HAVE BUMPED UP POPS TO LIKELY THURSDAY
AFTERNOON AND EVENING AS BULK OF PRECIPITATION WILL COME THROUGH
WITH COLD FRONT.
LOW CENTER WILL THEN MEANDER ACROSS THE EASTERN GREAT LAKES ON
FRIDAY. THE LOW WILL PUMP COLD AIR INTO THE AREA ON FRIDAY...AND
TEMPERATURES MAY DECREASE THROUGHOUT THE ENTIRE DAY. COLD AIR AND
ADDITIONAL MOISTURE WILL ALLOW FOR A GOOD CHANCE OF LAKE
EFFECT/UPSLOPE SNOW SHOWERS FRIDAY AND SATURDAY.
ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY WILL TUMBLE
BELOW NORMAL FOR FRIDAY AND SATURDAY BEHIND THE COLD FRONT.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
RECENT SURFACE AND SATELLITE DATA SHOW STRATOCUMULUS CEILINGS
ACROSS THE UPPER OHIO VALLEY WILL VARY BETWEEN MVFR AND VFR INTO
TONIGHT. ANY SHOWERS WILL BE ISOLATED IN COVERAGE AND LIGHT IN
INTENSITY AND SHOULD NOT ADD TO ANY RESTRICTIONS.
AS LOW PRESSURE CENTER FROM ARKANSAS MOVES NORTHEASTWARD ALONG THE
APPALACHIAN MOUNTAINS MONDAY...SHOWERS AND RESTRICTIONS WILL
LIKEWISE SPREAD SOUTH TO NORTH ACROSS THE UPPER OHIO VALLEY
DAYTIME MONDAY. AT THIS JUNCTURE HAVE NOT FORECASTED LOWER THAN
MVFR...BUT IFR CANNOT BE RULED OUT BY LATE MONDAY AFTERNOON.
SURFACE WINDS WILL BE FROM THE SOUTH AND SOUTHEAST AT 5 TO 15 KTS
INTO MONDAY.
.OUTLOOK.../MONDAY THROUGH FRIDAY/...
IFR RESTRICTIONS CAN OCCUR MONDAY NIGHT INTO TUESDAY MORNING DUE
TO SHOWERS WITH NORTHEASTWARD PASSAGE OF LOW PRESSURE CENTER. SOME
MVFR RESTRICTIONS MAY REMAIN TUESDAY AFTERNOON INTO WEDNESDAY
LINGERING POST SYSTEM COLD POOL STRATOCUMULUS. ANOTHER LOW
PRESSURE SYSTEM WILL BRING RAIN AND SNOW SHOWERS AND RESTRICTIONS
THURSDAY INTO FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1208 PM EST SUN DEC 16 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 521 AM EST SUN DEC 16 2012
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW ACROSS
NAMERICA WITH NRN BRANCH FLOW CONFINED TO CANADA. ACTIVE SRN BRANCH
FLOW OVER THE CONUS FEATURES A TROF OVER THE ROCKIES UPSTREAM OF A
RDG ALONG THE E COAST. SHRTWV EMBEDDED IN THE WSW FLOW ALF BTWN
THESE LARGER SCALE FEATURES IS RIPPLING THRU THE GREAT LKS BUT
WEAKENING AS IT MOVES INTO THE LARGER SCALE UPR RDG. THIS
DISTURBANCE WAS RESPONSIBLE FOR THE RA/SN MIX THAT IMPACTED UPR MI
ON SAT...BUT LATEST IR IMAGERY INDICATES CLOUD TOP TEMPS ARE WARMING
OVER THE AREA UNDER LARGER SCALE H85-5 QVECTOR DVGC LEFT IN THE WAKE
OF THIS WEAKENING SHRTWV DESPITE DEEP MSTR SHOWN ON THE LOCAL 00Z
RAOBS. LINGERNIG PCPN IS ON THE LIGHT SIDE AND CONSISTS OF MAINLY
SCT -SHSNRA OVER THE E HALF OF THE CWA CLOSER TO THE DEPARTING
SHRTWV. SFC TEMPS REMAIN WELL ABV NORMAL...MAINLY 34 TO 39 AT 09Z.
SOME FOG HAS FORMED AS WELL UNDER THE UPR SUBSIDENCE/DRYING. JUST TO
THE W THERE IS ANOTHER AREA OF COLDER CLOUD TOPS OVER MN ASSOCIATED
WITH ANOTHER WEAKER SHRTWV NEAR MPX AND A NRN BRANCH DISTURBANCE
NEAR LK WINNIPEG. UNDER THE BAND OF HIER RADAR REFLECTIVIES...MANY
LOCATIONS OVER THE E HALF OF MN ARE REPORTING SOME -SN...MIXED WITH
-RA AT A FEW SPOTS.
FCST CONCERNS IN THE SHORT TERM REVOLVE ARND LINGERING PCPN
CHCS/PTYPE ASSOCIATED WITH DEPARTING DISTURBANCE AND THEN ON TIMING/
PTYPE OF POPS ASSOCIATED WITH PAIR OF SHRTWVS TO THE W.
TODAY...EXPECT LINGERING PCPN OVER MAINLY THE E HALF ASSOCIATED WITH
FIRST SHRTWV TO FADE THIS MRNG AND PERHAPS GIVE WAY TO SOME
-DZ/-FZDZ IN UPSLOPE AREAS IMPACTED BY LLVL SE FLOW AS THE
DISTURBANCE/ACCOMPANYING FORCING SHIFTS TO THE E AND DEEP QVECTOR
DVGC/SUBSIDENCE/UPR DRYING TAKES HOLD. BUT STRIPE OF PCPN TO THE W
WL BEGIN TO SHIFT E INTO THE WRN CWA BY 12Z AS THE PAIR OF SHRTWVS/
ACCOMPANYING H7-3 QVECTOR CNVGC MOVE TO THE E. HOWEVER...MODELS SHOW
THE QVECTOR CNVGC WEAKENING WITH TIME...PROBABLY BECAUSE OF
INCREASING CAD IN THE WAKE OF H85 LO SHIFTING THRU THE UPR LKS. SO
SUSPECT PCPN AMOUNTS ASSOCIATED WITH THE INCOMING BAND OF SN MIXED
WITH RA WL BE GREATEST OVER THE W BUT STILL ON THE LIGHT SIDE.
TONIGHT...LINGERING PCPN WL TRANSITION TO LES AS PAIR OF SHRTWVS TO
THE W FADE AND THE WNW FLOW IN THE WAKE OF H85 LO MOVING NE THRU
ONTARIO ADVECTS COLDER AIR INTO THE UPR LKS UNDER MID LVL DRYING.
HOWEVER...FCST H85 TEMPS FCST NO LOWER THAN -8 TO -9C /COMPARED TO
WATER TEMPS IN THE 4-5C RANGE/ AS WELL AS PLACEMENT OF THE DGZ ABV
THE LLVL MSTR SUGGEST THIS LES SHOULD BE RELATIVELY LIGHT.
MAINTAINED THE HIER LIKELY POPS OVER THE NW CWA WITH MORE FVRBL LLVL
CNVGC/UPSLOPE WIND COMPONENT/GREATER THERMAL INSTABILITY. BUT EVEN
THERE...ANY SN ACCUM SHOULD BE AOB 2 INCHES.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 521 AM EST SUN DEC 16 2012
MONDAY...THE WEAK SFC LOW PRES WILL ONLY SLOWLY LIFT TO THE
NORTHEAST OF THE AREA AS THE MID/UPPER LEVEL TROUGH FROM NW ONTARIO
AND MANITOBA INTO THE NRN GREAT LAKES PERSISTS. WITH LITTLE OR NO
LARGE SCALE FORCING OVER THE AREA AND 850 MB TEMPS ONLY TO AROUND
-8C...LAKE INDUCED CAPE/INSTABILITY FOR ANY LES WILL ONLY BE
MARGINAL. THERE WILL STILL BE ENOUGH 850-750 MB MOISTURE OVER THE
AREA (INVERSION HEIGHTS NEAR 7K FT) FOR SCT/NMRS -SHSN EARLY MONDAY
INTO THE KEWEENAW AND FOR AREAS FROM MUNSING EASTWARD. HOWEVER...ONLY
LIGHT SNOWFALL AMOUNT OF AN INCH OR LESS ARE EXPECTED.
MONDAY NIGHT INTO TUE...WITH WINDS BACKING TO THE WEST AND BECOMING
LIGHT/ANTICYLONIC ALONG WITH FALLING INVERSION HEIGHTS AS A WEAK
RIDGE BUILD INTO THE AREA...ANY LINGERING LES WILL DIMINISH AND END
MON NIGHT WITH LITTLE OR NO ADDITIONAL ACCUMULATION. ONLY WEAK
FORCING WITH A SHORTWAVE TROUGH BRUSHING THE LATE MON NIGHT INTO TUE
WILL NOT BE ENOUGH TO SUPPORT ANY ADDITIONAL PCPN. A SHRTWV AND
ASSOCIATED BAND OF 285K-290K ISENTROPIC LIFT MOVING OUT OF THE
PLAINS INTO WI LATE TUE INTO TUE NIGHT COULD BRING SOME PATCHY LIGHT
SNOW INTO WEST UPPER MI.
WED-SAT...MODELS CONTINUE TO ADVERTISE POTENTIAL FOR A MAJOR WINTER
STORM SYSTEM MOVING OUT OF THE SOUTHERN PLAINS INTO THE CENTRAL
GREAT LAKES. THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE
TRACK OF THE SYSTEM WITH CONSENSUS BRINGING THE SFC LOW THROUGH LOWER
MI. HOWEVER...SIGNFICANT UNCERTAINTY REMAINS WITH THE EVENTUAL TRACK
AND STRENGTH AT THIS TIME FRAME. THE MAIN CLUSTER OF SOLUTIONS FROM THE
GFS ENSEMBLES AND OPERATIONAL GFS/ECMWF/UKMET WOULD BRING THE SYSTEM
CLOSE ENOUGH TO UPPER MI FOR SIGNFICANT SYNOPTIC SNOW ACROSS THE EAST
HALF OF THE CWA THU INTO THU NIGHT. UNLESS THE STORM AND DEEPER
MOISTURE MOVE TOO FAR TO THE SOUTH...A SIGNFICANT LAKE ENHANCED SNOW
TRANSITIONING TO PURE LES WOULD ALSO BE LIKELY FOR NORTH WIND FAVORED
SNOWBELTS INTO FRI. WITH A DEEP LOW PRES SYSTEM LIKELY...THERE WILL
BE THE POTENTIAL FOR VERY DIFFICULT TRAVEL CONDITIONS WITH SN/BLSN.
ADDITIONAL LES FOR N TO NW SNOWBELTS IS ALSO POSSIBLE INTO SATURDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1208 PM EST SUN DEC 16 2012
EXPECT IFR/LIFR CONDITIONS TO PREDOMINATE THRU THIS AFTERNOON AT ALL
3 SITES WITH LINGERING LLVL MSTR ACCOMPANYING PASSAGE OF A SFC LO
PRESSURE TROF. SOME VLIFR CONDITIONS ARE LIKELY EARLY AT CMX AS
WELL. CONDITIONS ARE LIKELY TO IMPROVE TO MVFR TNGT AT IWD/SAW WITH
W FLOW IN THE WAKE OF THE TROF PASSAGE BRINGING A BIT DRIER LLVL AIR
AS WELL A DOWNSLOPE WIND COMPONENT TO SAW. IFR CONDITIONS ARE LIKELY
TO PERSIST THE ENTIRE PERIOD AT CMX WITH UPSLOPE WIND ALSO MOISTENED
BY PASSAGE OVER LK SUP.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 521 AM EST SUN DEC 16 2012
AS A LO PRES TROF SHIFTS E ACROSS THE LAKE TODAY...EXPECT
DIMINISHING SE WINDS OVER THE E. ALLOWED GOING GALE WARNING FOR THE
FAR E TO EXPIRE AT 09Z AS SCHEDULED. FOLLOWING THE TROF PASSAGE THRU
TONIGHT...PLAN ON A WIND SHIFT TO THE WNW W TO E. BUT A FAIRLY WEAK
PRES GRADIENT THRU TONIGHT SHOULD KEEP THESE WINDS NO HIER THAN
15-25 KTS.
NORTH GALES ARE POSSIBLE LATE THURSDAY INTO FRIDAY AS A DEEPENING LOW
PRESSURE SYSTEM MOVES FROM THE MID MISSISSIPPI VALLEY INTO THE
CENTRAL GREAT LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLB
AVIATION...07
MARINE...KC/JLB
AREA FORECAST DISCUSSION
NWS JACKSON MS
412 PM CST SUN DEC 16 2012
.DISCUSSION...
A LARGE RAIN SHIELD CONTINUES OVER MUCH OF THE ARKLAMISS AS OF LATE
AFTERNOON AND THIS MAKES CONFIDENCE IN REDEVELOPMENT OF THE SEVERE
WEATHER POTENTIAL A LITTLE SHAKY FOR THIS EVENING AND OVERNIGHT.
HOWEVER...MOST GUIDANCE REMAINS CONVINCING IN THE STORM REDEVELOPMENT
SCENARIO AS STRONGER LIFT IS FORECAST TO DEVELOP WITH THE APPROACH
OF A STRONG MID LEVEL SHORTWAVE TROUGH AND HEIGHT FALL CENTER (500 MB
> 80M) AND ACCESS TO 330K+ THETAE.
WE ARE FOLLOWING THE COURSE AND CONTINUE TO MENTION THE POSSIBILITY
FOR SEVERE WEATHER OVER ABOUT THE SOUTHEAST HALF OF THE ARKLAMISS
AFTER 900 PM. THERE IS SOME DISAGREEMENT AMONG THE MODELS ABOUT WHEN
EXACTLY STORMS WILL RE- INITIATE IN OUR AREA...AND IT COULD BE LATER
GIVEN STRONGER STABILIZATION FROM THE CURRENT RAIN SHIELD. THE MOST
RECENT RUN OF THE HRRR IS ACTUALLY LESS EMPHATIC WITH
DEVELOPMENT...SO THE POSSIBILITY EXISTS THAT REDEVELOPMENT WILL NOT
OCCUR AT ALL. IF THE 12Z GFS PANS OUT...WE WILL SEE A RETURN OF MIXED
LAYER CAPE ~500 J/KG AND BACKING LOW LEVEL SHEAR VECTORS WITH
CONTINUED STRONG DEEP LAYER SHEAR. THIS WOULD SUPPORT A FEW SEVERE
STORMS AND WILL CONTINUE THE MENTION IN THE HWO/GRAPHICS.
DEPENDING ON REDEVELOPMENT OF STORMS TONIGHT...WE WILL NEED TO
CONTINUE A CLOSE MONITOR FOR HEAVY RAINFALL WITH ABUNDANT MOISTURE
STILL AVAILABLE AND WITH A CONTINUED SET-UP FOR TRAINING OF
STORMS...PARTICULARLY OVER SOUTHEAST PORTIONS OF THE FORECAST AREA.
TSTMS COULD LINGER MONDAY MORNING ALONG THE I-59 CORRIDOR BEFORE THE
COLD FRONT/DRY LINE CAN PASS THROUGH. OTHERWISE...EXPECT A DRY
WEATHER REGIME TO TAKE HOLD BY MONDAY AFTERNOON WITH ABOVE CLIMATIC
NORMAL TEMPERATURES. /EC/
TUESDAY THROUGH SUNDAY...
SURFACE HIGH PRESSURE WILL SHIFT OFF TO OUR EAST ON TUE BRINGING
BACK RETURN FLOW OFF THE GULF. UNSEASONABLY WARM CONDITIONS CAN BE
EXPECTED TUE AND WED AS A RESULT/ESPECIALLY WED WHERE HIGHS IN THE
LOW TO MID 70S WILL COME IN SOME 15 DEGREES ABOVE NORMAL FOR MID
DEC. THE WARMTH WILL NOT LAST LONG THOUGH AS A POTENT COLD FRONT IS
PROGGED TO CROSS THE REGION STARTING EARLY THU MORNING.
THE UPPER WAVE ASSOC WITH THIS NEXT SYSTEM WILL CROSS INTO THE
CENTRAL PLAINS WED EVENING INDUCING A DEEP SURFACE LOW OVER THE
OKLAHOMA PANHANDLE THAT WILL TRACK EAST NORTHEAST ACROSS SOUTHERN MO
AND EVENTUALLY THE GREAT LAKES. THE SYNOPTIC SETUP OFFERED BY THE
MODELS WITH THIS SYSTEM IS QUITE IMPRESSIVE...AND AT FIRST GLANCE IT
WOULD APPEAR THAT SEVERE WEATHER FOR THE ARKLAMISS WOULD BE A SLAM
DUNK. HOWEVER THE DETAILS OFFER A DIFFERENT STORY...AT LEAST FOR
NOW. WHILE ROBUST WIND FIELDS JUST AHEAD OF THE FRONT DRAW UP AMPLE
AMOUNTS OF MOISTURE/DEW POINTS CLIMBING NEAR OR ABOVE 65 DEG FOR A
GOOD PORTION OF THE AREA AND PW VALUES RISING ABOVE 1.5 IN/
TEMPERATURES ALOFT ARE RATHER WARM(H5 TEMPS -10 TO -11) WHICH
SIGNIFICANTLY REDUCES MID LEVEL LAPSE RATES AND RESULTANT
INSTABILITY. WE WILL HAVE TO KEEP AN EYE ON THIS TO SEE IF THE
MODELS TREND COOLER ALOFT BECAUSE IF THEY DO...AND THE SYNOPTIC
SETUP REMAINS SIMILAR...WE COULD BE LOOKING AT DECENT SEVERE WEATHER
POTENTIAL LATE WED INTO THU MORNING. FOR NOW...WILL OMIT MENTION OF
ANY SEVERE WEATHER IN THE HWO/GRAPHICS.
MUCH COOLER AIR WILL FILTER ACROSS THE REGION IN WAKE OF THE FRONT
WITH TEMPERATURES LIKELY FALLING THROUGH THE DAYLIGHT HOURS THU.
STRONG MIXING WILL ALLOW WINDY CONDITIONS TO DEVELOP THU AND ITS
FEASIBLE A WIND ADVISORY MAY BECOME NECESSARY FOR AT LEAST THE
DELTA...IF NOT AREAS FURTHER SOUTH AND EAST AS WELL. HIGH PRESSURE
WILL TRANSIT THE DEEP SOUTH FRI INTO THE FIRST PART OF THE WEEKEND
BEFORE RAIN CHANCES RETURN EARLY NEXT WEEK. /BK/
&&
.AVIATION...
CEILINGS SHOULD RAIN IN MVFR-IFR CONDITIONS ALONG WITH
MVFR/IFR IN RAIN AND THUNDERSTORM CONDITIONS THROUGH THE NIGHT. THE
BEST CHANCE OF THUNDERSTORMS WILL AFFECT THE SOUTHERN THIRD OF THE
REGION. WINDS WILL BE FROM THE SOUTH AT 10 TO 15 KNOTS WITH SOME HIGHER
GUSTS...THEN TURN SOUTHWEST AROUND 5 TO 10 KNOTS ON MONDAY MORNING.
THE RAINS AND CLOUDS WILL BE DECREASING FROM THE NORTHWEST ON MONDAY...THUS
VFR CONDITIONS WILL PREVAIL BY LATE MORNING INTO THE AFTERNOON./17/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 57 71 38 70 / 70 17 6 0
MERIDIAN 58 74 37 68 / 83 22 7 0
VICKSBURG 57 69 35 71 / 50 11 5 0
HATTIESBURG 62 74 41 70 / 91 31 7 0
NATCHEZ 60 67 38 69 / 69 11 5 0
GREENVILLE 56 64 41 69 / 27 9 4 0
GREENWOOD 55 69 38 70 / 44 11 5 0
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
EC/BK/17/
AREA FORECAST DISCUSSION
NWS JACKSON MS
1058 AM CST SUN DEC 16 2012
.UPDATE...
...RISK FOR HEAVY RAINFALL AND STRONG TO SEVERE STORMS CONTINUES...
A LARGE CONVECTIVE SYSTEM IS STEADILY TRACKING ESE ACROSS THE ARKLAMISS
LATE THIS MORNING. 12Z JAN/LIX SOUNDINGS REVEALED WEAK LAPSE RATES...
AND CURRENT ANALYSES INIDICATE MIXED LAYER CAPE ONLY ~200 J/KG AHEAD
OF THE SYSTEM. LATEST DGX VAD WIND PROFILE SHOWS A DISRUPTED LOOKING
SHEAR PROFILE WITH WESTERLY WIND COMPONENTS IN THE 2000-4000 FT RANGE
YIELDING 0-1KM SHEAR VECTORS VEERED TO NEARLY PARALLEL WITH CONVECTIVE
LINE.
SO THE STRONG/SEVERE STORM POTENTIAL IS AT LEAST TEMPORARILY IN
A LULL...BUT THE CONCERN FOR HEAVY RAIN CONTINUES. THERE IS PLENTY
OF MOISTURE TRANSPORT WITH PRECIPITABLE WATER NEAR 1.6 INCHES AND A
VERY MOIST BOUNDARY LAYER WITH DEWPOINTS REACHING THE MID 60S. FLASH
FLOOD GUIDANCE IS HIGH FOR THIS TIME OF THE YEAR AND THUS FAR THE
MCS HAS BEEN PROGRESSIVE ENOUGH TO LIMIT FLOODING CONCERNS...BUT WILL
KEEP A CLOSE EYE ON BACKING LOW LEVEL WINDS AHEAD OF MESOSCALE
CONVECTIVE VORTICES PROPAGATING ALONG THE LINE WHICH COULD SLOW THE
LINE DOWN AND AT LEAST TEMPORARILY RAISE FF CONCERNS. ALSO...WILL
MONITOR FOR INCREASING BOUNDARY LAYER MOISTURE AND INSTABILITY IN THE
WARM SECTOR WHICH COULD ELEVATE THE STRONG/SVR STORM POTENTIAL THIS
AFTERNOON. /EC/
&&
.PREV DISCUSSION... /ISSUED 406 AM CST SUN DEC 16 2012/
..HEAVY RAIN/FEW SEVERE STORMS POSSIBLE TODAY INTO TONIGHT...
SHORT TERM...(TODAY THROUGH MONDAY NIGHT)...
MAIN CONVECTIVE BAND ACROSS N MS INTO SRN AR STEADILY EXPANDING/
GETTING STRONGER PAST SEVERAL HOURS. OTHERWISE...ISOLATED LIGHT SHRA
CONTINUE TO CROSS N AND W PORTIONS OF THE CWFA WITH LOW STRATUS
ELSEWHERE. STALLED FRONTAL BOUNDARY STILL HANGING BACK NEAR A KJBR-
KTYR LINE AS AN UPSTREAM S/WV OVER THE SRN ROCKIES TO THE TX BIG BEND
MOVES EWD AT 40KTS TOWARD THE OZARKS. A POWERFUL UPPER JET WITH EPAC
CONNECTIONS WILL AID IN RAINFALL PRODUCTION GETTING RAMPED UP TODAY
WITH CONTINUED EXPANSION OF THE PRE-FRONTAL CONVECTION. LIKELY
TRAINING OF CONVECTION IN THIS SCENARIO DURING THE DAYLIGHT HOURS
COULD GENERATE AN AXIS OF 2-4 INCHES RATHER EASILY. MODEL CONSENSUS
PLACES THE HEAVIEST RAINFALL FROM AROUND NATCHEZ TO MERIDIAN BETWEEN
NOON AND MIDNIGHT...SOME RISK FOR LOCALIZED FLASH FLOODING WILL EXIST
BUT WILL HOLD OFF A FLASH FLOOD WATCH UNTIL THE AXIS BECOMES MORE
DEFINED SINCE 3HR FFG STILL ABOVE 3 INCHES MOST AREAS.
UNTIL THE DIURNAL INSTABILITY GETS ADDED TO THE MIX...LOOK FOR THE
EXPANDING RAIN BAND TO PUSH TO NEAR A WINNSBORO TO JACKSON TO
COLUMBUS AXIS BY ABOUT NOON...PER LATEST RUC PROGS. THEN THE RISK
FOR A FEW STRONG/SEVERE STORMS WILL BE INCREASING S OF THAT AXIS
THROUGH THE EVENING HOURS FUELED BY PWATS RISING NEAR 1.5 INCHES...
0-3KM HELICITIES OF 200-300M*M/S*S...6.5C 7-500MB LAPSE RATES...
INCREASINGLY COUPLED 850-200MB DIFFERENTIAL DIVERGENCE...850MB THETA
E AXIS OF 334K AND LEFT EXIT REGION OF A 65KT 500MB JET STREAK.
AT THIS POINT IT LOOKS LIKE THE AREA WITH THE GREATEST SEVERE
WEATHER RISK WILL BE ACROSS THE SERN HALF OF THE CWA WHERE THE BEST
COMBINATION OF SHEAR AND INSTABILITY WILL BE CO-LOCATED. EVEN A
DECENT TORNADO RISK COULD DEVELOP FOR SERN MS FROM 00-06Z AS A LAYER
OF MARINE GULF AIR OF 65-68F DEWPTS ATTEMPTS TO SURGE NWD...REF NEW
SPC DAY ONE OUTLOOK FOR UPDATES.
PRIMARY ASCENT PUSHES OFF TO OUR E MONDAY MORNING WITH DEVELOPING
UNIDIRECTIONAL FLOW FROM THE WSW BY MIDDAY. DRYING PWATS DROP TO
NEAR ONE HALF INCH BY MIDDAY ACROSS I-55...AND CLOSER TO ONE THIRD
INCH BY MIDNIGHT MONDAY NIGHT WHEN BEST CLEARING EXPECTED OF THE
REMAINING CLOUD COVER. DUE TO THE BEST RAINFALL AXIS POSITION LYING
ALONG OR S OF I-20 DURING SUNDAY...HAVE ADDED PATCHY FOG TO SRN HALF
OF CWFA LATE MONDAY NIGHT WHERE WET GROUNDS AND COOLER L40S TEMPS
EXIST UNDER NEAR CALM SURFACE WIND/CLEAR SKY CONDITIONS.
AS FOR TEMPS/POPS...RAISED GFS MOS POPS TODAY FOR NWRN HALF BEFORE
NOON AND THE SERN HALF DURING THE AFTERNOON THROUGH OVERNIGHT
PERIODS. MOS TEMP RANGE SEEMED A BIT HIGH SO NARROWED THE HIGH/LOW
RANGE A BIT THROUGH MONDAY WHILE ACCEPTING GUIDANCE FOR MONDAY
NIGHT. /40/
LONG TERM...(TUESDAY THROUGH SUNDAY)...
SURFACE HIGH PRESSURE WILL SHIFT OFF TO OUR EAST ON TUE BRINGING
BACK RETURN FLOW OFF THE GULF. UNSEASONABLY WARM CONDITIONS CAN BE
EXPECTED TUE AND WED AS A RESULT/ESPECIALLY WED WHERE HIGHS IN THE
LOW TO MID 70S WILL COME IN SOME 15 DEGREES ABOVE NORMAL FOR MID
DEC. THE WARMTH WILL NOT LAST LONG THOUGH AS A POTENT COLD FRONT IS
PROGGED TO CROSS THE REGION STARTING EARLY THU MORNING.
THE UPPER WAVE ASSOC WITH THIS NEXT SYSTEM WILL CROSS INTO THE
CENTRAL PLAINS WED EVENING INDUCING A DEEP SURFACE LOW OVER THE
OKLAHOMA PANHANDLE THAT WILL TRACK EAST NORTHEAST ACROSS SOUTHERN MO
AND EVENTUALLY THE GREAT LAKES. THE SYNOPTIC SETUP OFFERED BY THE
MODELS WITH THIS SYSTEM IS QUITE IMPRESSIVE...AND AT FIRST GLANCE IT
WOULD APPEAR THAT SEVERE WEATHER FOR THE ARKLAMISS WOULD BE A SLAM
DUNK. HOWEVER THE DETAILS OFFER A DIFFERENT STORY...AT LEAST FOR
NOW. WHILE ROBUST WIND FIELDS JUST AHEAD OF THE FRONT DRAW UP AMPLE
AMOUNTS OF MOISTURE/DEW POINTS CLIMBING NEAR OR ABOVE 65 DEG FOR A
GOOD PORTION OF THE AREA AND PW VALUES RISING ABOVE 1.5 IN/
TEMPERATURES ALOFT ARE RATHER WARM(H5 TEMPS -10 TO -11) WHICH
SIGNIFICANTLY REDUCES MID LEVEL LAPSE RATES AND RESULTANT
INSTABILITY. WE WILL HAVE TO KEEP AN EYE ON THIS TO SEE IF THE
MODELS TREND COOLER ALOFT BECAUSE IF THEY DO...AND THE SYNOPTIC
SETUP REMAINS SIMILAR...WE COULD BE LOOKING AT DECENT SEVERE WEATHER
POTENTIAL LATE WED INTO THU MORNING. FOR NOW...WILL OMIT MENTION OF
ANY SEVERE WEATHER IN THE HWO/GRAPHICS.
MUCH COOLER AIR WILL FILTER ACROSS THE REGION IN WAKE OF THE FRONT
WITH TEMPERATURES LIKELY FALLING THROUGH THE DAYLIGHT HOURS THU.
STRONG MIXING WILL ALLOW WINDY CONDITIONS TO DEVELOP THU AND ITS
FEASIBLE A WIND ADVISORY MAY BECOME NECESSARY FOR AT LEAST THE
DELTA...IF NOT AREAS FURTHER SOUTH AND EAST AS WELL. HIGH PRESSURE
WILL TRANSIT THE DEEP SOUTH FRI INTO THE FIRST PART OF THE WEEKEND
BEFORE RAIN CHANCES RETURN EARLY NEXT WEEK. /BK/
&&
.AVIATION...
MVFR-IFR CEILINGS SHOULD DETERIORATE TO FREQUENTLY IFR
CONDITIONS IN ADVANCING RAIN/TSRA BAND SAGGING SWD THROUGH THE TAF
SITES. SSWLY SFC WINDS WL BECOME A LITTLE GUSTY AHEAD OF THE
PRECIPITATION THRU THE AFTN BEFORE WEAKENING THIS EVENING. SHRA AND
TSRA ACTIVITY WILL BE STRONGEST/HEAVIEST ACROSS THE I-20 CORRIDOR
AND SWD BY THIS AFTERNOON WHILE IT ALL WILL GRADUALLY END FROM NW TO
SE LATER TONIGHT FOR THE DELTA REGION AND DURING MONDAY MORNING FOR
OUR ERN/SRN SITES. A GRADUAL SHIFT TO WSWLY LOW LEVEL FLOW WILL
RETURN VFR CONDITIONS AND WILL HELP THE RAINS ON MONDAY WITH
CLEARING SKIES MONDAY EVENING. 17/40/
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
337 PM CST SUN DEC 16 2012
.SHORT TERM...TONIGHT AND TOMORROW.
UPPER LEVEL SATELLITE DATA HAS SHOW A FEW SMALL DISTURBANCES
SHIFTING ACROSS THE PLAINS TODAY...ONE OF WHICH BROUGHT SOME LIGHT
SNOW TO PORTIONS OF THE CWA THIS MORNING. TRACE AMOUNTS UP NEAR
A HALF OF AN INCH WERE REPORTED...AND BY MIDDAY PRECIPITATION
TRENDS HAD FALLEN BACK TO JUST A FEW SCATTERED FLURRIES IN
NORTHEASTERN PORTIONS OF THE CWA. CLOUD COVER HAS BEEN
ANNOYING...THE NORTHEASTERN HALF OF THE CWA HAS BEEN STUCK UNDER
STUBBORN LOW LEVEL STRATUS...VS THE WESTERN HALF WHICH HAS SEEN
PLENTY OF SUN. SURFACE ANALYSIS SHOWS A RIDGE AXIS EXTENDING
THROUGH THE CENTRAL/EASTERN PORTIONS OF THE REGION...KEEPING WINDS
GENERALLY ON THE LIGHT AND AT TIMES VARIABLE SIDE. THANKS TO THE
CLOUD COVER...EASTERN LOCATIONS HAVE HUNG AROUND THE LOW 30S THIS
AFTERNOON...OUT WEST HAS REACHED INTO THE LOWER 40S.
KEPT THE FORECAST TONIGHT DRY...THOUGH MODELS ARE SHOWING ANOTHER
WEAK DISTURBANCE SWINGING THOUGH THE REGION...POTENTIALLY BRINGING
SOME ADDITIONAL LIGHT PRECIPITATION. AT THIS POINT...SHOULD ANY
PRECIPITATION FALL...IT LOOKS TO REMAIN JUST OFF TO THE
SOUTH/SOUTHWEST OF THE CWA. AT THE SURFACE...A WEAK TROUGH AXIS
GETS PUSHED THROUGH AS THE DISTURBANCE CROSSES...EVENTUALLY
BRINGING A WESTERLY COMPONENT TO THE WINDS. AHEAD OF THAT
SWITCH...CONCERNED ABOUT THE POTENTIAL FOR SOME PATCHY FOG
DEVELOPMENT...AS THE WINDS REMAIN LIGHT/CALM WITH NOT AS MUCH IN
THE WAY OF CLOUD COVER EXPECTED. WITH THE NAM/SREF BOTH SHOWING
REDUCED VISIBILITIES AND THE RAP NOT TOO FAR OUTSIDE THE CWA
BOUNDARY...DECIDED TO INSERT A PATCHY FOG MENTION ACROSS PORTIONS
OF SC NEB.
INTO MONDAY...EXPECTING TO SEE WEAK SHORTWAVE UPPER LEVEL RIDGING
OVER THE REGION...KEEPING CONDITIONS QUIET. SHOULD SEE VARIABLE
SKY COVER THROUGH THE DAY WITH UPPER LEVEL CLOUDS STREAMING IN.
AT THE SURFACE...THE CWA IS COMING UNDER INCREASING INFLUENCE OF
LOW PRESSURE DEVELOPING OVER THE HIGH PLAINS...RESULTING IN WINDS
BECOMING MORE SOUTHERLY WITH TIME. AFTER LOW TEMPERATURES TONIGHT
EXPECTED IN THE TEENS TO LOWER 20S...HIGHS ON MONDAY LOOK TO REACH
INTO THE LOWER 40S TO NEAR 50.
.LONG TERM...MONDAY NIGHT THROUGH SUNDAY.
MAIN CHALLENGE REMAINS DETERMINING CHANCES AND TIMING OF SNOW FOR
WEDNESDAY/WEDNESDAY NIGHT.
WE BEGIN THE LONG TERM FORECAST MONDAY NIGHT WITH ZONAL FLOW. THE
FLOW REMAINS QUITE PROGRESSIVE AS A SIGNIFICANT TROUGH DEVELOPS IN
THE WESTERN UNITED STATES BY TUESDAY. AS A RESPONSE TO THIS
DEEPENING TROUGH TO THE WEST...PLENTY OF WARM AIR WILL ARRIVE ON
TUESDAY AND PLACE OUR HIGH TEMPERATURES WELL ABOVE NORMAL BY ABOUT
15 DEGREES OR SO. THIS ABOVE NORMAL WEATHER WILL MOST CERTAINLY
NOT LAST AS THE TROUGH PROGRESSES QUICKLY TO THE EAST AND AN
ASSOCIATED COLD FRONT SWINGS IN FROM THE NORTHWEST VERY LATE
TUESDAY NIGHT INTO WEDNESDAY. A SHARP COOL DOWN WILL ENSUE.
THE TIMELINE FOR THIS NEXT WAVE IS TRENDING TOWARD A SOONER ARRIVAL
AND SOONER EXIT. ISENTROPIC LIFT BEGINS EARLY WEDNESDAY MORNING
BEHIND A QUICKLY MOVING COLD FRONT...WITH THIS FORCING GIVING WAY
TO MID-LEVEL FRONTOGENETIC FORCING LATER IN THE DAY.
ALSO...LARGER SCALE SYNOPTIC FORCING BECOMES STRONGER AS THE DAY
WEARS ON AND IS FORECAST TO BE RESPECTABLE FOR A SHORT
TIME...ADDING ANOTHER LAYER OF FORCING TO AID IN SNOW PRODUCTION.
THE ECMWF INDICATES THAT SYNOPTIC FORCING WILL PEAK NEAR 00Z
THURSDAY. THIS WAVE IS A QUICK HITTER...HOWEVER...WITH MOST IF NOT
ALL FORCING EAST OF THE CWA BY MIDNIGHT WEDNESDAY NIGHT...WHICH
WILL ALSO END ANY SNOW PRODUCTION. WITH THIS WAVE BEING SUCH A
QUICK HITTER...SNOW AMOUNTS ARE STILL ON TRACK FOR UP TO 4 INCHES
OR SO FOR SOMEBODY NEARBY...BUT THIS PROBABLY WOULD NOT BE A
UBIQUITOUS SNOW AMOUNT. IF THIS SYSTEM SLOWS DOWN JUST A
BIT...THIS COULD MEAN MORE SNOW WITH LARGER SNOW AMOUNTS AND
PLENTY OF WIND TO CREATE DRIFTING SNOW POTENTIAL. WIND ALOFT FOR
WEDNESDAY AFTERNOON AND EVENING IS QUITE STRONG AND BLOWING SNOW
WILL BE A POTENTIAL ISSUE. THERE IS ALSO SOME DISCREPANCY AMONG
MODELS WHERE THE TRACK OF THE 700 MB CLOSED LOW WILL BE AS THE NAM
DRAGS THIS LOW ACROSS THE CENTRAL CWA...WHILE THE ECMWF TAKES THE
700 MB LOW ACROSS CENTRAL KANSAS. THE GFS DOES NOT CLOSE THE LOW
OFF...BUT DOES FAVOR A SOLUTION CLOSER TO THE ECMWF. NO QUESTION
ABOUT PRECIPITATION TYPE SO FAR...AS SOUNDINGS INDICATE ALL SNOW
WITH THIS EVENT. WE TEND TO FAVOR A MORE SOUTHERN TRACK WITH THESE
PACIFIC SYSTEMS. ALSO WEDNESDAY MAY BE A TRICKY DAY FOR HOURLY
TEMPERATURES DEPENDING ON THE TIMING OF THE COLD FRONT. WE COULD
REACH HIGHS MORE TOWARD LATE MORNING RATHER THEN IN THE AFTERNOON.
ANYWAY...TEMPERATURES WILL PROBABLY GO ALMOST NOWHERE FROM THE
LOWS ON TUESDAY NIGHT. I CONTINUED TO GO COLDER THAN ALLBLEND FOR
TEMPERATURES FOR WEDNESDAY NIGHT AND BEYOND CONSIDERING POTENTIAL
SNOW COVER.
&&
.AVIATION...18Z TAF. LOOKING TO SEE SOME CLOUDS RIGHT ON THE
VFR/MVFR BRINK HANGING AROUND FOR AT LEAST A LITTLE WHILE THIS
AFTERNOON...ASSOCIATED WITH A WEAK DISTURBANCE AND SOME LINGERING
FLURRIES GRADUALLY SHIFTING EAST. OTHERWISE...VFR CONDITIONS ARE
CURRENTLY EXPECTED. SURFACE HIGH PRESSURE CURRENTLY IN PLACE OVER
THE REGION IS KEEPING WINDS ON THE LIGHT AND AT TIMES VARIABLE
SIDE...WHICH IS EXPECTED TO CONTINUE THROUGH THE AFTERNOON. MORE
WESTERLY WINDS WILL DEVELOP LATER TONIGHT AND CONTINUE THROUGH THE
END OF THE TAF PERIOD AS LOW PRESSURE SETS UP OVER THE HIGH
PLAINS...BUT SPEEDS EXPECTED TO REMAIN BELOW 10KTS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT/AVIATION...ADO
LONG...HEINLEIN
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1137 AM CST SUN DEC 16 2012
.AVIATION...18Z TAF. LOOKING TO SEE SOME CLOUDS RIGHT ON THE
VFR/MVFR BRINK HANGING AROUND FOR AT LEAST A LITTLE WHILE THIS
AFTERNOON...ASSOCIATED WITH A WEAK DISTURBANCE AND SOME LINGERING
FLURRIES GRADUALLY SHIFTING EAST. OTHERWISE...VFR CONDITIONS ARE
CURRENTLY EXPECTED. SURFACE HIGH PRESSURE CURRENTLY IN PLACE OVER
THE REGION IS KEEPING WINDS ON THE LIGHT AND AT TIMES VARIABLE
SIDE...WHICH IS EXPECTED TO CONTINUE THROUGH THE AFTERNOON. MORE
WESTERLY WINDS WILL DEVELOP LATER TONIGHT AND CONTINUE THROUGH THE
END OF THE TAF PERIOD AS LOW PRESSURE SETS UP OVER THE HIGH
PLAINS...BUT SPEEDS EXPECTED TO REMAIN BELOW 10KTS.
&&
.PREV DISCUSSION... /ISSUED 906 AM CST SUN DEC 16 2012/
UPDATE...MADE SOME CHANGES TO WEDNESDAY AND WEDNESDAY NIGHT
FORECAST. ADJUSTED THE GRADIENT FOR CHANCES OF PRECIPITATION ON
WEDNESDAY AND INCREASED CHANCES OF PRECIPITATION CENTRAL/SOUTH A
BIT. ALSO BROKE UP WEATHER AND CHANCES OF PRECIPITATION INTO 6
HOUR BLOCKS WEDNESDAY AND WEDNESDAY NIGHT...AS BOTH WEDNESDAY
MORNING AND LATE WEDNESDAY NIGHT APPEAR TO HAVE MUCH LOWER CHANCES
OF SNOW COMPARED TO WEDNESDAY AFTERNOON AND EVENING. ALSO ADJUSTED
SKY COVER TO BE COMPLETELY CLOUDY FOR WEDNESDAY AFTERNOON AND
EVENING.
PREV DISCUSSION... /ISSUED 433 AM CST SUN DEC 16 2012/
SHORT TERM...THROUGH 12Z WEDNESDAY. EVENING UPPER AIR ANALYSIS
INDICATES A LONGWAVE TROUGH OVER THE WESTERN HALF OF THE CONUS
WITH QUASI- ZONAL FLOW ACROSS THE EAST. MID AND UPPER LEVEL JET
ENERGY EXTENDS FROM WEST-TEXAS...EAST/NORTHEAST INTO THE SOUTHERN
PLAINS AND LOWER MISSISSIPPI VALLEY...AND THEN FARTHER EAST INTO
THE SOUTHEASTERN CONUS. MID AND UPPER LEVEL TROPOSPHERIC FLOW OVER
OUR AREA REMAINS FAIRLY WEAK AS A RESULT...MAXING OUT AT AROUND
60KTS NEAR 200MB PER 00Z SOUNDING DATA FROM KLBF. WATER VAPOR
IMAGERY SHOWS PLENTY OF MID LEVEL MOISTURE ADVANCING
EAST/NORTHEAST ALONG THE MID TO UPPER LEVEL JET AXIS ACROSS THE
SOUTH AND SOUTHEASTERN CONUS...WITH DRIER MID LEVEL AIR NOTED
FARTHER NORTH. WATER VAPOR IMAGERY ALSO INDICATES A COMPACT MID
LEVEL SHORT WAVE OVER COLORADO...BEGINNING TO EJECT OUT FROM THE
MAIN LONGWAVE TROUGH. AT THE SURFACE A RIDGE OF HIGH PRESSURE IS
NOTED EXTENDING FROM THE NORTHERN HIGH PLAINS...SOUTH/SOUTHEAST
INTO THE CENTRAL PLAINS. A COLD FRONT IS ALSO NOTED EXTENDING FROM
SOUTHWEST TO NORTHEAST ACROSS KANSAS...SOUTHWESTERN MISSOURI AND
IOWA. THE LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE
NORTHWEST AS A RESULT. RADAR DATA FROM KUEX...KLNX AND KGLD
CONTINUE TO SHOW PRECIPITATION OVER SOUTHWESTERN NEBRASKA AND
NORTHWESTERN KANSAS...WITH SNOW BEING REPORTED OVER SOME AREAS AS
WELL. FOR LOCATIONS ACROSS OUR WESTERN CWA...WHERE KUEX HAS
INDICATED PRECIPITATION FOR THE PAST FEW HOURS...PRECIPITATION AT
THE SURFACE HAS YET TO BE REPORTED AS THE LOWER TROPOSPHERE STILL
APPEARS TOO DRY FOR SUCH ACTIVITY TO BE REALIZED.
GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL
SUGGEST THE MID LEVEL SHORT WAVE...APPROACHING OUR AREA FROM
COLORADO...WILL CONTINUE PUSHING ACROSS THE CENTRAL PLAINS DURING
THE DAY TODAY. DPVA AND WEAK MID LEVEL THERMAL ADVECTION AHEAD OF
THE MID LEVEL TROUGH AXIS...WORKING IN CONCERT WITH AN AXIS OF
FRONTOGENESIS NEAR 700MB...SHOULD SUSTAIN PRECIPITATION PRODUCTION
OVER NORTHWESTERN KANSAS AND SOUTHWESTERN NEBRASKA THROUGH THE
NEXT FEW HOURS...WITH PRECIPITATION PERHAPS MAKING IT TO THE
SURFACE ACROSS WESTERN PORTIONS OF OUR AREA AS WELL. FORECAST
PROXIMITY SOUNDINGS FROM ACROSS MUCH OF OUR CWA...PER THE NAM AND
OPERATIONAL GFS...SUGGEST THE LOWER TROPOSPHERE WILL HAVE TO DO
QUITE A BIT OF SATURATING FARTHER EAST BEFORE PRECIPITATION IS
REALIZED AT THE SURFACE...THUS CONFIDENCE IS NOT ALL THAT HIGH
THAT ANY MEASURABLE PRECIPITATION WILL BE REALIZED EAST OF HIGHWAY
183. BUT FARTHER WEST ACROSS THE AREA...WHERE MID LEVEL
PRECIPITATION HAS BEEN ONGOING FOR SEVERAL HOURS NOW AND CEILINGS
ARE LOWERING CLOSER TO 2000FT AGL..CONFIDENCE IS SOMEWHAT HIGHER
OF PRECIPITATION BEING REALIZED AT THE SURFACE. GIVEN ALL
THIS...WENT AHEAD WITH CHANCE POPS ACROSS OUR FAR WEST...ROUGHLY
WEST OF HIGHWAY 183...WITH SLIGHT CHANCE POPS FARTHER EAST. THE
RAP...NAM AND OPERATIONAL GFS ALL SUGGEST THE MID LEVEL TROUGH
AXIS WILL BEGIN CLEARING THE AREA BY 15Z...THUS ALLOWING THE BULK
OF THE OMEGA AND MID LEVEL FRONTOGENESIS TO ALSO PUSH EAST OF OUR
AREA BY LATE MORNING OR MIDDAY. QPF FIELDS FROM VARIOUS MODELS
SUGGEST VERY LIGHT PRECIPITATION MAY STILL BE REALIZED OVER
PORTIONS OF OUR AREA BEYOND 15Z...BUT GIVEN THE LIMITED FORCING BY
THIS TIME OPTED TO ONLY GO WITH 20% POPS 15-18Z...AND ISOLATED
FLURRIES AND SPRINKLES AFTER 18Z.
ALTHOUGH A FEW LOCATIONS ACROSS SOUTHWESTERN NEBRASKA AND
NORTHWESTERN KANSAS HAVE REPORTED RECEIVING ONE OR TWO INCHES OF
SNOW SINCE 06Z...CURRENT RETURNS FROM KUEX...KLNX AND KGLD ALL
SUGGEST THE ONGOING PRECIPITATION IS FAIRLY LIGHT AT THIS HOUR AND
CURRENTLY DO NOT EXPECT THIS TREND TO CHANGE AS THIS ACTIVITY
WORKS INTO OUR AREA. GIVEN ALL THIS...WILL GO AHEAD AND PRESENT A
COUPLE TENTHS OF AN INCH OF SNOWFALL TO MOST LOCATIONS WEST OF
HIGHWAY 183...WITH A FEW LOCATIONS ACROSS WESTERN DAWSON...WESTERN
GOSPER AND WESTERN FURNAS COUNTIES CLOSER TO A HALF INCH.
IT IS WORTH NOTING THAT FORECAST PROXIMITY SOUNDINGS FROM OUR
EAST/NORTHEASTERN CWA PER THE NAM AND RAP SUGGEST AND ELEVATED
WARM LAYER NEAR 850MB COULD PRESENT TEMPERATURES SLIGHTLY ABOVE
FREEZING THROUGH 15Z WHILE SURFACE TEMPERATURES REMAIN BELOW
FREEZING. 850MB TEMPERATURES FOR ALL SITES ACROSS OUR CWA ARE
EXPECTED TO FALL BELOW FREEZING BY NO LATER THAN 15Z HOWEVER...PER
THE NAM AND RAP...AND GIVEN THE LOW CONFIDENCE/VERY LOW CHANCE OF
MEASURABLE PRECIPITATION ACTUALLY BEING OBSERVED THAT FAR EAST
BEFORE 15Z...OPTED TO KEEP ANY MENTION OF -ZR OUT OF THE FORECAST.
THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL SUGGEST YET
ANOTHER MID LEVEL SHORT WAVE WILL PUSH OVER THE CENTRAL PLAINS
TONIGHT. FORECAST PROXIMITY SOUNDINGS FROM ACROSS THE CWA PER THE
NAM AND OPERATIONAL GFS SUGGEST HOWEVER THAT TROPOSPHERIC MOISTURE
WILL BE TOO LACKING FOR PRECIPITATION PRODUCTION AND AS A
RESULT...LEFT TONIGHT DRY. SUBTLE MID AND UPPER LEVEL RIDGING IS
EXPECTED TO MOVE INTO THE CENTRAL CONUS MONDAY THROUGH TUESDAY
NIGHT. THE RESULTANT LACK IN OVERALL KINEMATIC FORCING SHOULD THEN
PRESENT DRY CONDITIONS TO FINISH OUT THE SHORT TERM FORECAST
PERIOD.
WEAK LOW LEVEL COLD AIR ADVECTION ACROSS THE REGION TODAY SHOULD
PRESENT SLIGHTLY COOLER TEMPERATURES TODAY WHEN COMPARED TO
YESTERDAY...WITH AFTERNOON HIGHS IN THE 30S AND 40S CURRENTLY
FORECAST. WEAK LOW LEVEL WARM AIR ADVECTION AND A DOWN-SLOPING
COMPONENT TO THE LOW LEVEL WIND FIELD SHOULD THEN PRESENT A SUBTLE
WARMING TREND TO FINISH OUT THE SHORT TERM FORECAST PERIOD...WITH
HIGHS IN THE 40S AND 50S EXPECTED MONDAY AND TUESDAY.
LONG TERM...WEDNESDAY THROUGH SATURDAY
THE MAIN STORY: WED CONTINUES TO THREATEN SOME WINTRY WX AND
SLIPPERY TRAVEL FOR PART OF THE FCST AREA WITH TEMPS AVERAGING
SEASONABLY COLD THROUGH THE PERIOD.
PATTERN: THE HEMISPHERIC HGT ANOMALIES ARE LIKELY TO MAINTAIN
-NAO/ -PNA CONFIGURATION...ESSENTIALLY WORKING AGAINST EACH OTHER
TO BRING ANY REAL ARCTIC COLD DEEP INTO THE CONUS. HOWEVER...THE E
PACIFIC LONGWAVE TROF WILL CONTINUE TO DELIVER OCCASIONAL PCPN
THREATS. THE FIRST OCCURRED WITH THIS PAST FRI NIGHT`S RAINFALL
/WHICH BROUGHT WIDESPREAD 0.5 TO 0.75"/. THE NEXT ARRIVES WED AND
THE PATTERN LOOKS FAVORABLE FOR ANOTHER DURING THE WEEK OF
CHRISTMAS.
HAZARDS: WE CONTINUE TO SEE POTENTIAL FOR SOME ACCUMULATING SNOW
WED-WED EVE. THE THREAT CONTINUES HIGHLIGHTED IN THE HWO.
PCPN: WED-WED EVE CONFIDENCE IS HIGH FOR A LIGHT SNOWFALL EVENT.
CONFIDENCE IS AVERAGE FOR A MODERATE SNOWFALL...PROBABLY S AND E
OF HASTINGS "IF" IT WAS TO OCCUR.
THE DAILY DETAILS...
LOW TEMPS ALL PERIODS WERE LOWERED TO BIAS CORRECTED ALL-BLEND
GUIDANCE. THIS COORDINATED WITH LBF SINCE THIS LOWERED TEMPS MOST
OVER OUR NW COUNTIES. WED HIGH TEMPS WERE ALSO LOWERED TO MEX
TEMPS AND WAS COORDINATED WITH ALL SURROUNDING OFFICES.
DETERMINISTIC MODELS AND NAEFS/EC ENSEMBLE MEANS CONTINUE TO
SUGGEST HIGH CONFIDENCE IN LEE CYCLOGENESIS WED...WITH THE LOW
EJECTING ACROSS KS /OR NRN OK?/ INTO THE MID MS VALLEY.
HOWEVER...ENSEMBLE SPREAD OF 8-10 MB EXISTS NW OF THE MEAN SFC LOW
POSITION... SUGGESTING DIFFERENCES IN TIMING/LOCATION AMONG THE
VARIOUS POSSIBLE OUTCOMES IN THE GUIDANCE ENVELOPE.
THERE ARE A COUPLE GFS ENSEMBLE MEMBERS THAT OFFER 0.5" OF COMMA-
HEAD QPF IN VICINITY OF HWY 81...SIMILAR TO THE 00Z/15 EC. SO
ALTHO IT/S A LOW PROBABILITY...SOME POTENTIAL CONTINUES FOR
WARNING SNOWFALL AMOUNTS OVER OR SOMEWHERE NEARBY OUR FCST AREA.
FOR NOW GFS ENSEMBLE PROBABILITIES ARE HIGH /70 PERCENT/ FOR 0.1"
IN 24 HRS ALONG AND E OF HWY 281.
REGARDLESS OF HOW MUCH SNOW FALLS...WED IS LIKELY TO BE A RAW
NASTY DAY WITH A SHARP N WIND AND FALLING AFTERNOON TEMPS.
FCST FOR WED IS ESSENTIALLY CLOUDY IN CAA WITH -SN DEVELOPING IN
INCREASINGLY GUSTY NE WINDS. NOT SURE IT SNOWS EVERYWHERE. TRACK
DEPENDENT. BEST GUESS AT THIS POINT IS LOWEST CHANCE FOR
MEASURABLE SNOW IS N AND W OF GRI. TEMPS PROBABLY RISE LITTLE FROM
MORNING LOWS AND THEN FALL AFTER MIDDAY.
WED NGT: ANY SNOW ENDS PROBABLY BY MIDNIGHT. CLEARING FROM THE SW.
A BLUSTERY NIGHT WITH WIND CHILLS AS LOW AS -5F AT TIMES.
WINDS WERE INCREASED ABOVE GUIDANCE 12 PM WED TO 12 PM THU.
THU: UPPER TROF TRANSITIONS TO NW FLOW. SUNNY. BLUSTERY N WINDS
EVENTUALLY SUBSIDE AS SFC RIDGE MOVES IN LATE. NEAR NORMAL TEMPS
BUT IT WILL FEEL COLD GIVEN THE MILD DEC THUS FAR...ESPECIALLY
WITH A BITING N WIND AND WIND CHILLS NEAR ZERO IN THE
MRNG...ESPECIALLY N AND W OF GRI.
FRI: SUNNY AND PROBABLY 5F ABOVE NORMAL WITH LIGHT SW WINDS.
SAT: QUITE A BIT OF SPREAD WITH AMPLITUDE/POSITION OF THE RIDGE
BUT MOST MODELS/ENSEMBLE MEMBERS SUGGEST A DRY COLD FRONTAL
PASSAGE. FOR NOW SEASONABLY COLD TEMPS.
ARCTIC COLD: WE/VE NOTICED VARIOUS RUNS OF THE GFS/EC HAVE
THREATENED TO BRING DOWN SOME BITTER ARCTIC COLD THE LAST WEEK OF
DEC. THE GFS ENSEMBLES CONTINUE TO HINT AT A POSSIBLE 2-3 DAY
SPELL OF COLD TEMPS IN THIS TIMEFRAME. THE DETERMINISTIC 5-DAY
MEANS FROM THE LAST COUPLE RUNS OF THE GFS/EC WANT TO DEVELOP A
HUDSON BAY LOW UPSTREAM OF THE GREENLAND BLOCK. WOULD LIKE TO SEE
MORE ENSEMBLE SUPPORT BEFORE GETTING HOPES US. HOWEVER...WE WOULD
NEED SOME HELP EITHER VIA A TRANSITION TO A +PNA /WRN N AMERICA
RIDGING/ OR SOME HIGH- LATITUDE RIDGING OVER AK. THERE ARE SOME
HINTS OF THIS IN THE ENSEMBLES.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AVIATION...ADO
UPDATE...HEINLEIN
SHORT...BRYANT
LONG...HALBLAUB
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1016 AM CST SUN DEC 16 2012
.DISCUSSION...
MAIN CHANGE FOR THE MORNING UPDATE WAS TO BUMP UP CLOUD COVER FOR
THE REST OF THE DAY. LOTS OF LOW LEVEL MOISTURE TRAPPED UNDER THE
SUBSIDENCE INVERSION WITH HIGH PRESSURE AND SAT LOOPS SHOW NO BIG
BREAKS IN THE CLOUDS UNTIL NORTH OF LAKE WINNIPEG. HRRR AND LAV
GUIDANCE SEEM TO SUPPORT A PRETTY CLOUDY DAY FOR THE REST OF THE
DAY...SO BUMPED UP CLOUDS. LOW LEVEL WARM AIR ADVECTION WILL MOVE
SOUTH OF THE AREA AND WEAK COLD AIR ADVECTION MOVING IN. THINK
THAT TEMPS WILL STEADY OFF AND THEN SLOWLY START TO DROP...WITH
THE EXCEPTION OF THE FAR SOUTHEASTERN COUNTIES. PATCHY FOG HAS
TAKEN OVER NORTH CENTRAL ND...BUT MOST OF IT HAS STAYED WEST OF
OUR COUNTIES. STILL...WILL INCLUDE A PATCHY MENTION IN THE FAR
NORTHWESTERN COUNTIES FOR THE REST OF THE MORNING AS WEB CAMS SHOW
SOME FOG ALONG THE CENTER OF THE SFC HIGH.
&&
.AVIATION...
MOST LOCATIONS HAVE STAYED IFR OR LOWER UNDER AN EXTENSIVE STRATUS
DECK. A FEW LOCATIONS COULD RECOVER TO MVFR FOR A TIME THIS
AFTERNOON...BUT CONDITIONS WILL STAY PRETTY CLOUDY. CEILINGS WILL
COME DOWN AGAIN AND RETURN TO IFR OR LOWER AFTER SUNSET. NORTHERLY
WINDS AT LESS THAN 10 KTS WILL BECOME LIGHT AND VARIABLE.
&&
.PREV DISCUSSION... /ISSUED 331 AM CST SUN DEC 16 2012/
SHORT TERM...
CHALLENGES FOR THE FORECAST INCLUDE CLOUD COVER AND ITS IMPACTS ON
TEMPS ALONG WITH AREAL COVERAGE AND POPS FOR LIGHT SNOW TUESDAY.
MODELS IN FAIR AGREEMENT AND WILL USE A BLEND FOR THE FORECAST.
WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROUGH SLOWLY SLIDING
ACROSS MANITOBA THIS MORNING. MODELS IN AGREEMENT WITH THIS
FEATURE CUTTING OFF AND LINGERING ACROSS SOUTHERN CANADA AS THE
300MB FLOW REMAINS SPLIT ACROSS THE NORTHERN PLAINS. AT THE SFC
RELATIVELY WEAK HIGH PRESSURE IS CENTERED OVER W ND AND W
MANITOBA. STRATUS DECK ACROSS THE FA AND UNDER THE HIGH WILL BE
SLOW TO ERODE WITH LITTLE MIXING AND A RELATIVELY MOIST LOW LEVEL.
MODEL SOUNDINGS SHOW A STRONG INVERSION WITH A DRY LAYER ABOVE THE
LOW LEVEL RH. EXPECTING LITTLE IN THE WAY OF SOLAR TODAY WITH
TEMPS NEARLY STEADY AS CURRENT READINGS IN THE TEENS AND LOW 20S
PERSIST FOR MUCH OF THE DAY.
AFOREMENTIONED SFC HIGH TO DRIFT SLOWLY EAST AND IS PROGGED TO BE
CENTERED OVER THE FA ON MON 12Z. THERMAL PROFILE REMAINS UNCHANGED
THOUGH CLOUD COVER TO IMPACT TEMPS...ANY HOLES OR CLEARING IN THE
STRATUS DECK WILL ALLOW THE SFC TO RADIATE OUT AND TEMPS TO FALL
QUICKLY. GIVEN THE UNCERTAINTY OF CLEARING AND LOW LEVEL RH
THINKING MORE CLOUDS THAN NOT WITH TEMPS IN THE SINGLE DIGITS
FORECASTED FOR MON MORNING LOWS. HIGHS MONDAY A BIT LOWER AS A
COOLER START WITH LITTLE SOLAR AND MIXING TO LIMIT TEMP RISE.
SFC HIGH SLOWLY MOVES EAST WITH RETURN FLOW SETTING UP MONDAY
NIGHT INTO TUESDAY AS ZONAL FLOW ALOFT BRINGS IN A WEAK WAVE WITH
MODELS INDICATING SOME WAA PRECIP ON TUESDAY. THE NAM CONTINUES TO
BE MUCH QUICKER WITH THE BAND OF PRECIP LIFTING FROM SW TO NE
ACROSS THE FA THAN THE OTHER MODELS THOUGH ITS PLACEMENT OF THE
SFC LOW ON 18Z TUESDAY IS SIMILAR...IN THE MT/ND/SASK AREA. KEPT
THE CHC/SCHC POPS TUESDAY.
LONG TERM (WEDNESDAY-SATURDAY)...
A FAIRLY QUIET PERIOD APPEARS TO BE IN STORE. THERE WILL BE A SLIGHT
CHANCE FOR LIGHT SNOW ON WEDNESDAY WITH AN UPPER TROUGH MOVING THROUGH
THE REGION...OTHERWISE EXPECT RIDGING TO DOMINATE. ENERGY FROM THE
NORTHERN STREAM WILL BRIEFLY FLATTEN THE UPPER RIDGE FRIDAY-
SATURDAY...BUT SHOULD REMAIN NORTH OF THE INTERNATIONAL BORDER.
OVERALL...TEMPERATURES WILL BE NEAR OR SLIGHTLY BELOW NORMAL.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
JR
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1233 PM EST SUN DEC 16 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL SLIDE INTO THE AREA THIS AFTERNOON AND
EVENING. LOW PRESSURE WILL DEVELOP ALONG THIS FRONT AND MOVE
ACROSS THE AREA MONDAY. HIGH PRESSURE WILL BUILD IN TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW LEVEL MOISTURE WILL REMAIN IN PLACE ACROSS THE CWA TODAY.
CEILINGS HAVE BEGUN TO LIFT SLIGHTLY THIS MORNING...AND RADAR
ECHOES HAVE DIMINISHED IN COVERAGE AS WELL. A SLIGHT CHANCE OF
SHOWERS WILL BE KEPT IN THE FORECAST...MAINLY IN THE EAST AND JUST
FOR THE NEXT FEW HOURS...BEFORE LIMITING ANY CHANCE OF
PRECIPITATION TO THE FAR SOUTHEAST THROUGH THE AFTERNOON HOURS.
THE LATEST HRRR RUNS ARE SHOWING THAT ANY CONVECTION THAT DEVELOPS
WILL OCCUR NEAR OR AFTER 00Z AND WILL LIKELY BE LIMITED TO THE
SOUTH AND SOUTHEAST. GIVEN THE REMAINING UNCERTAINTY IN BOTH
FORCING AND INSTABILITY...THERE APPEARS TO BE NO REASON TO
INCREASE POPS THIS EVENING (THOUGH A SLIGHTLY HIGHER CHANCE WILL
EXIST LATER IN THE OVERNIGHT HOURS).
TEMPERATURES WERE MOSTLY ON TRACK...WITH SOME SLIGHT UPWARD
ADJUSTMENTS MADE IN THE SOUTH. WARM ADVECTION WILL DOMINATE THE
TEMPERATURE CURVE TODAY...WITH ESSENTIALLY ZERO DIRECT SUNLIGHT
EXPECTED.
PREVIOUS DISCUSSION >
SOUTHERLY FLOW WILL CONTINUE ACROSS THE REGION TODAY. PLENTY OF
LOW LEVEL MOISTURE IN PLACE ALTHOUGH THERE SHOULD BE SOME BREAKS
IN THE CLOUDS ESPECIALLY LATER IN THE DAY. A WEAK COLD FRONT WILL
PUSH INTO THE REGION LATE THIS AFTERNOON. AND THERE WILL BE A WEAK
MID LEVEL IMPULSE TRACKING ACROSS THE AREA. BUT OVERALL FORCING IS
MINIMAL. SO ONLY KEPT SLIGHT CHANCE POPS IN FOR TODAY.
TEMPERATURES WILL BE WELL ABOVE NORMAL WITH A MOS BLEND USED AS A
BASE FOR HIGHS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
BOUNDARY WILL WORK FURTHER INTO THE FORECAST AREA TONIGHT BEFORE
STALLING AS LOW PRESSURE DEVELOPS ALONG THE FRONT OFF TO THE
SOUTHWEST. AS THE LOW APPROACHES LATE TONIGHT EXPECT SHOWERS TO
DEVELOP IN THE SOUTHERN COUNTIES. THE LOW WILL CONTINUE TO TRAVEL
ALONG THE FRONT AND ACROSS THE REGION ON MONDAY. MODELS ARE
TRENDING TOWARDS A LESS DEVELOPED LOW WHICH SHOULD KEEP THE
GREATER COVERAGE OF SHOWERS FROM SPREADING TOO FAR NORTHWEST. BUT
STILL ENOUGH UNCERTAINTY TO KEEP CHANCE POPS GOING ALL THE WAY
INTO WEST CENTRAL OHIO. THERE WILL BE SOME INSTABILITY ALONG AND
SOUTH OF THE FRONT SO DID INCLUDE A CHANCE OF THUNDERSTORMS THERE.
A SHORT WAVE WILL TRAVEL ACROSS THE REGION MONDAY NIGHT AND WITH
MOISTURE STILL LINGERING IN THE AREA THAT MAY GENERATE SOME
ADDITIONAL SHOWERS AREA WIDE. AFTER IT PASSES RIDGING WILL
TEMPORARILY MOVE IN ALLOWING FOR SOME DRYING.
WARMER GUIDANCE LOOKED MORE REASONABLE FOR TONIGHT BUT A BLEND WAS
USED MONDAY NIGHT. LEANED TOWARDS COOLER GUIDANCE FOR HIGH
TEMPERATURES BOTH DAYS.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
UPPER RIDGING WILL CONTINUE INTO WEDNESDAY AHEAD OF AN APPROACHING
DEEPENING TROUGH. SO EXPECT DRY AND UNSEASONABLY WARM CONDITIONS
ONCE AGAIN. AS THE UPPER SYSTEM PIVOTS NORTHEAST TOWARDS THE
REGION THE ASSOCIATED SURFACE LOW WILL PUSH A WARM FRONT THROUGH
THE AREA WEDNESDAY NIGHT. THIS WILL LEAD TO STEADY OR RISING
TEMPERATURES OVERNIGHT. SHOWERS WILL SPREAD IN FROM THE WEST LATE
WEDNESDAY NIGHT AND SWEEP ACROSS THE REGION ON THURSDAY. WITH WEAK
INSTABILITY FORECAST AT THIS POINT BUT FAIRLY STRONG DYNAMICS...
CANNOT RULE OUT SOME THUNDER ALTHOUGH IT IS NOT INCLUDED IN THE
FORECAST YET. THE LOW WILL LIFT NORTH OF THE AREA BUT AFTER A
STRONG COLD FRONT SWEEPS THROUGH THE TEMPERATURES WILL FALL IN THE
AFTERNOON.
00Z GUIDANCE HAS COME INTO AGREEMENT IN KEEPING THIS SYSTEM
PROGRESSIVE. SO THERE WILL ONLY BE A BRIEF WINDOW FOR WRAP AROUND
AND LAKE ENHANCED SNOW SHOWERS TO AFFECT THE REGION THURSDAY NIGHT
AND FRIDAY. HIGH PRESSURE WILL BUILD IN WITH TEMPERATURES AT OR
SLIGHTLY BELOW SEASONAL NORMALS.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
WITH PLENTY OF VARIABLE CONDITIONS EXPECTED IN THE NEXT 24
HOURS...THIS SET OF TAFS WAS DIFFICULT...AND CONFIDENCE IN
SPECIFICS IS NOT ESPECIALLY HIGH.
LOW LEVEL MOISTURE WILL CONTINUE ACROSS THE REGION THROUGH THE
PERIOD. CLOUDS HAVE GENERALLY BEEN ON A LIFTING TREND THROUGH THE
MORNING...AND VFR CEILINGS ARE EXPECTED TO BE MORE PREVALENT INTO
THE AFTERNOON. HOWEVER...SOME MVFR CONDITIONS ARE STILL
POSSIBLE...ESPECIALLY IN THE FIRST FEW HOURS OF THE VALID TAFS.
SSW WINDS HAVE BEEN OCCASIONALLY GUSTY (AROUND 18-24 KNOTS) BUT
SOMETIMES MORE CALM. THE TAFS WILL INCLUDE THE GUSTS...BUT THEY
MAY NOT OCCUR AT ALL TIMES.
SHOWERS AND POSSIBLY THUNDERSTORMS ARE EXPECTED TO DEVELOP
TONIGHT...THOUGH THE HIGHEST CONCENTRATION SHOULD REMAIN SOUTH OF
THE TAF SITES. VCSH WITH TEMPO -SHRA HAS BEEN ADDED TO ACCOUNT FOR
THIS ACTIVITY AFTER SUNSET...THOUGH CONFIDENCE IN THUNDER
AFFECTING A TAF SITE IS EXTREMELY LOW. CEILINGS WILL ALSO LOWER
AGAIN DURING THE OVERNIGHT...WITH MVFR VISIBILITIES AND CEILINGS
IN THE LOW MVFR RANGE. THOUGH NOT SPECIFICALLY FORECAST...SOME IFR
CEILINGS ARE POSSIBLE NEAR SUNRISE.
LOW PRESSURE MOVING NORTHEAST THROUGH THE OHIO VALLEY WILL BRING
ANOTHER CHANCE FOR PRECIPITATION ON MONDAY. THIS LOOKS TO BEGIN
NEAR THE END OF THE TAF PERIOD...AND MVFR CONDITIONS ARE EXPECTED
TO BE PREVAILING. LATE IN THE PERIOD...WINDS WILL BEGIN A SHIFT
FROM SOUTHERLY TO WESTERLY.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES WILL BE POSSIBLE FROM
MONDAY THROUGH TUESDAY. MVFR CONDITIONS ARE AGAIN EXPECTED ON
THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...HATZOS
SHORT TERM...
LONG TERM...
AVIATION...HATZOS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
238 PM CST SUN DEC 16 2012
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
238 PM CST SUN DEC 16 2012
MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES AND TYPE FOR
TUESDAY AND WEDNESDAY.
CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A POTENT SHORTWAVE TROUGH APPROACHING THE PACIFIC NORTHWEST
AND BROAD TROUGHING ENCOMPASSING MUCH OF THE CENTRAL U.S. INTO THE
WESTERN GREAT LAKES. WITHIN THIS BROAD TROUGHING...THERE ARE VERY
FEW SHORTWAVES THAT LOOK TO HAVE ANY IMPACT ON OUR FORECAST AREA
DURING THE NEXT FEW DAYS. THE ONLY SHORTWAVE REALLY OF NOTE WAS OVER
WESTERN PORTIONS OF MONTANA AND WYOMING. AT THE SURFACE...LOW
PRESSURE WAS OVER UPPER MICHIGAN WHILE HIGH PRESSURE COVERED THE
DAKOTAS INTO WESTERN MINNESOTA. IN-BETWEEN THE TWO...NORTHERLY WINDS
ARE DRIVING COLDER LOW LEVEL AIR INTO THE FORECAST AREA. SURFACE
TEMPERATURES HAVE FALLEN INTO THE 20S OVER PORTIONS OF SOUTHEAST
MINNESOTA WHILE THE REST OF THE AREA REMAINS MOSTLY IN THE 30S. THE
COLD AIR EXTENDS UP TO 850MB WITH 12Z SOUNDINGS FROM BIS...ABR AND
MPX SHOWING -4C TEMPERATURES. ALONG WITH THE COLDER AIR...EXTENSIVE
LOW STRATUS EXISTS FROM THE DAKOTAS INTO THE FORECAST AREA...TRAPPED
BELOW A COLD FRONTAL/SUBSIDENCE INVERSION SHOWN ON THE
AFOREMENTIONED SOUNDINGS. AS THE COLD AIR HAS BEEN FLOWING IN...SOME
FOG HAS DEVELOPED...DUE TO RECENT RAIN AND MELTING SNOW.
VISIBILITIES DROPPED EVEN DOWN TO 1/4SM MILE IN SOME PLACES IN
SOUTHEAST MINNESOTA. LAST ITEM TO NOTE IS A QUICK SNOW DEPTH
COMPARISON TO OBSERVED. THE 16.12Z NAM HAS WAY TOO MUCH SNOW ALONG
AND SOUTH OF I-90...AS ITS SNOW DEPTH INFORMATION HAS NOT UPDATED
SINCE 00Z ON THE 15TH.
TONIGHT AND MONDAY...WEAK UPPER RIDGING WITHIN THE BROAD TROUGH IS
FORECAST TO BUILD INTO THE AREA FOR TONIGHT AND MUCH OF MONDAY...
AHEAD OF THAT SHORTWAVE OVER WESTERN MONTANA AND WYOMING. GOOD MODEL
AGREEMENT EXISTS THAT THE SHORTWAVE WILL REACH WESTERN MINNESOTA BY
00Z TUESDAY. THE WEAK UPPER RIDGING BUILDING IN COMBINED WITH THE
SURFACE RIDGING COMING IN AT THE SURFACE FAVORS DRY CONDITIONS
THROUGH MONDAY. THE BIGGEST QUESTION IS IF THIS STRATUS CAN
DISSIPATE AT ALL. TOUGH TO USE THE NAM...PARTICULARLY ALONG AND
SOUTH OF I-90...SINCE IT HAS TOO MUCH SNOW AND THIS IS INFLUENCING
ITS HANDLING OF BOUNDARY LAYER. HOWEVER...BOTH GFS AND RAP SOUNDINGS
WHICH HAVE A BETTER HANDLE ON THE SNOW DEPTH SITUATION SUGGEST THE
STRATUS WILL DEFINITELY STAY IN PLACE TONIGHT. LOOKS LIKE THERE IS
ENOUGH STIRRING OF THE BOUNDARY LAYER TO PREVENT MORE THAN PATCHY
FOG. PERHAPS THERE IS A SHOT OF DIURNAL MIXING OUT THE STRATUS
TOMORROW...THOUGH MID AND HIGH CLOUDS WILL INCREASE AHEAD OF THE
APPROACHING SHORTWAVE. AS A RESULT...MAINLY CLOUDY CONDITIONS WILL
PREVAIL. THIS MEANS TEMPERATURES FOR THE MOST PART ARE GOING TO BE
INFLUENCED BY ADVECTION. A BLEND OF GUIDANCE SEEMED REASONABLE FOR
BOTH LOWS AND HIGHS.
MONDAY NIGHT AND TUESDAY...THE SHORTWAVE OVER WESTERN MINNESOTA AT
00Z TUESDAY IS SLATED TO CROSS THE AREA MONDAY NIGHT...BUT IT LOOKS
LIKE IT WILL COME THROUGH WITH LITTLE FANFARE OUTSIDE OF SOME
MID/HIGH CLOUDS. THIS IS BECAUSE OF PLENTIFUL DRY AIR IN-BETWEEN
THESE MID/HIGH CLOUDS AND A POSSIBLE HANGING AROUND VERY LOW STRATUS
DECK. OF MORE SIGNIFICANCE IS LATE IN THE NIGHT AND HEADING INTO THE
DAY TUESDAY...WHEN WARM ADVECTION IMPACTS FROM THE POTENT TROUGH
APPROACHING THE PACIFIC NORTHWEST CURRENTLY BEGIN TO MOVE IN. AT 12Z
TUESDAY...MODELS SHOW THE POTENT TROUGH...ALBEIT IN A MUCH WEAKER
STATE AFTER CROSSING THE NORTHERN ROCKIES...STRETCHED FROM THE
DAKOTAS INTO NORTHWEST IOWA. THIS TROUGH SLIDES EAST THROUGH MUCH OF
THE AREA ON TUESDAY...IN RESPONSE TO BUILDING 500MB HEIGHTS
DOWNSTREAM OF DEEP TROUGHING COMING INTO CALIFORNIA. MODELS HAVE
COME INTO GOOD AGREEMENT SHOWING A BAND OF ISENTROPIC LIFT/MID-LEVEL
FRONTOGENESIS ACCOMPANYING THIS TROUGH PASSAGE...YIELDING A BAND OF
QPF LIFTING NORTHWARD THROUGH THE FORECAST AREA DURING THE DAY
TUESDAY. PRECIPITATION COULD DEVELOP AS EARLY AS AFTER MIDNIGHT
MONDAY NIGHT AS SUGGESTED BY THE 16.12Z GFS AND SOME OF THE 16.09Z
SREF ENSEMBLES. HAVE CONFINED A 20 PERCENT CHANCE FOR MONDAY NIGHT
TO SOUTHEAST MINNESOTA. GIVEN THE GOOD AGREEMENT FOR TUESDAY...
INCREASED CHANCES UP TOWARDS 50...HIGHEST NORTH OF I-90 WHERE THE
BEST CONSENSUS EXISTS. HIGHER CHANCES MAY BE NECESSARY IN FUTURE
FORECASTS. AMOUNTS DO NOT LOOK LIKE A WHOLE LOT...BETWEEN THE BAND
LIFTING NORTH AND LIFT THAT IS QUALITATIVELY MODERATE AT BEST.
PRECIPITATION TYPE COULD BE AN ISSUE...WITH THE 16.12Z NAM SHOWING A
WARM NOSE AROUND 2C AROUND 2000 FT AGL ACCOMPANYING THE BAND. THE
GFS SUGGESTS ALL SNOW AND WILL PLAY THAT ROUTE FOR NOW AS IT SEEMS
THAT THE WARM NOSE SHOULD ACTUALLY COME IN SOUTH OF THE BAND. AFTER
THE PASSAGE OF THE BAND...THE GFS AND NAM SHOWS SKIES CLEARING OUT.
THIS MAY OCCUR AND IF IT DOES...TEMPERATURES SOUTH OF I-90 COULD POP
INTO THE 40S. FOR NOW TAKING A CONSENSUS APPROACH AS THE ECMWF
SUGGESTS A SLOWER LIFT NORTH OF THE BAND.
TUESDAY NIGHT AND WEDNESDAY...ATTENTION BEGINS TO SHIFT TO THE
TROUGHING OVER CALIFORNIA AT 00Z WEDNESDAY. GOOD MODEL AGREEMENT
EXISTS OF IT SLIDING ACROSS ARIZONA AND NEW MEXICO DURING THIS
PERIOD...RESULTING IN DEEPENING LOW PRESSURE ACROSS THE OKLAHOMA AND
TEXAS PANHANDLES. DOWNSTREAM...500MB HEIGHTS CONTINUE TO RISE...
PARTICULARLY ACROSS THE LOWER AND MID-MISSISSIPPI RIVER VALLEY. THIS
IN TURN SETS UP A STRENGTHENING MID-LEVEL FRONTOGENESIS ZONE
INITIALLY ACROSS COLORADO...THEN SPREADING UP THROUGH KANSAS...
EASTERN NEBRASKA AND EVENTUALLY IOWA BY WEDNESDAY AFTERNOON. THE
16.12Z NAM APPEARS TO BE AN OUTLIER IN EJECTING THE SURFACE SYSTEM
NORTH TO KANSAS CITY BY 00Z THURSDAY...COMPARED TO THE
GFS/ECMWF/UKMET/CANADIAN WHICH ALL HOLD IT BACK OVER OKLAHOMA. THE
FASTER EJECTING NAM WOULD ALLOW WARMER AIR TO ENTER SOUTHERN
SECTIONS OF THE FORECAST AREA ON WEDNESDAY AS WELL AS PRECIP INTO
SOUTH CENTRAL MINNESOTA. THE LATTER MORE FAVORED GROUP REQUIRES
HAVING SOME CHANCES OF PRECIPITATION...SNOW OR RAIN/SNOW MIX...TO
SOUTHERN SECTIONS OF THE FORECAST AREA WEDNESDAY AFTERNOON.
OTHERWISE...THE REST OF THE PERIOD IS DRY. WEAK PRESSURE GRADIENT
AFTER MIDNIGHT TUESDAY NIGHT PLUS POSSIBLE CLEARING WOULD
RESULT IN GOOD RADIATIONAL COOLING CONDITIONS...THOUGH THE EXTENT OF
CLEARING IS UNCERTAIN AT THIS TIME. PLUS...MID/HIGH CLOUDS MAY
ALREADY BE APPROACHING THE AREA ASSOCIATED WITH THE FRONTOGENESIS
TUESDAY NIGHT...THICKENING OVER THE AREA ON WEDNESDAY. THUS HAVE
STAYED TOWARD A GUIDANCE BLEND FOR BOTH HIGHS AND LOWS.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
238 PM CST SUN DEC 16 2012
FOCUS CONTINUES TO BE ON THE DEEP TROUGHING COMING OUT OF NEW MEXICO
AND THE ASSOCIATED SURFACE SYSTEM IN OKLAHOMA.
ECMWF/CANADIAN/GFS/UKMET AND GFS ENSEMBLES ALL STILL SUGGEST PHASING
OF THIS TROUGHING AND A NORTHERN STREAM TROUGH DROPPING DOWN INTO
THE NORTHERN PLAINS. HOWEVER...TRENDS OF THE ABOVE MODELS ARE ALL
SHOWING THIS PHASING TAKING PLACE FARTHER EAST WITH THE TRACKS NOW
MAINLY GOING UP THROUGH INDIANA. THIS TREND IS GETTING CONCERNING
FOR PRECIPITATION FOR WEDNESDAY NIGHT AND THURSDAY...ESPECIALLY
OVER THE NORTHWEST 1/3 OR SO WHERE IT COULD END UP DRY. CERTAINLY
PLENTY OF TIME FOR ADJUSTMENTS FOR THE TRACK GIVEN THAT THE DEEP
TROUGH PORTION IS STILL SOUTH OF THE ALEUTIANS. ADJUSTED THE
PRECIPITATION CHANCES SLIGHTLY DOWNWARD FOR WEDNESDAY NIGHT AND
THURSDAY TO ACCOUNT FOR THE SOUTHEAST TREND...BUT AT LEAST AT THIS
TIME THE SOUTHEAST HALF OF THE FORECAST AREA STILL LOOKS GOOD TO
PICK UP SOME ACCUMULATING SNOW.
AFTER THE WEDNESDAY NIGHTTHURSDAY SYSTEM...THE PATTERN LOOKS QUIET
WITH UPPER RIDGING DOMINATING THE WESTERN HALF OF THE U.S. OR SO AND
THE FORECAST AREA IN WEST TO NORTHWEST FLOW AND HIGH PRESSURE AT THE
SURFACE. CERTAINLY SOME COLDER AIR WILL COME DOWN IN THE WAKE OF THE
SYSTEM...SENDING TEMPERATURES DOWN TO NEAR OR JUST BELOW NORMAL...
BUT IT APPEARS THIS WILL BE SHORT-LIVED AS 500MB HEIGHTS RISE.
&&
.AVIATION...THIS AFTERNOON THROUGH MONDAY
1200 PM CST SUN DEC 16 2012
MVFR/IFR CIGS/VSBYS WILL PERSIST ACROSS MUCH OF THE AREA THRU
TONIGHT AND MONDAY. CONSIDERABLE MOISTURE REMAINS TRAPPED ACROSS THE
REGION...IN/UNDER A SFC-800MB INVERSION. AREA SOUNDINGS SHOW THIS
MOISTURE TO BE SOME 3K-4K FT DEEP OVER MUCH OF MN/IA/WI. WITH WEAK
GRADIENTS AND A WEAK RIDGE OF HIGH PRESSURE TO BUILD OVER THE AREA
TONIGHT...LITTLE IN THE WAY OF ADVECTION LOOKS TO OCCUR PLUS THERE
IS PLENTY OF MOISTURE UPSTREAM OVER THE DAKOTAS/NORTHERN MN. THE
HIGH HOLDS THE INVERSION IN PLACE AS WELL. THUS...CONTINUED IFR
CIGS/VSBYS AT KRST THRU THE TAF PERIOD. KLSE A LITTLE BETTER BEING
IN THE VALLEY WITH CIGS AROUND 1K FT AND VFR OR MVFR VSBYS. THE
STRATUS BLANKET AND SOME WEAK NORTHWEST GRADIENT FLOW SHOULD KEEP
THE FOG FROM BECOMING DENSE AGAIN TONIGHT.
ANY IMPROVEMENT MONDAY LOOKS TO BE SLOW WITH WARM ADVECTION AND AN
INCREASE OF MOISTURE SPREADING INTO THE AREA AHEAD OF A WEAK
SHORTWAVE TROUGH MOVING ACROSS THE UPPER MIDWEST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
238 PM CST SUN DEC 16 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1200 PM CST SUN DEC 16 2012
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
305 AM CST SUN DEC 16 2012
THE MAIN FOCUS OVER THE NEXT FEW DAYS IS ON THE DEPARTING
PRECIPITATION TODAY FOLLOWED BY THE CHANCE FOR SNOW ON TUESDAY.
LIGHT RAIN/DRIZZLE AND LIGHT SNOW WILL COME TO AN END FROM WEST TO
EAST TODAY AS A MID LEVEL SHORTWAVE TROUGH PROPAGATES TO THE NORTHEAST
INTO THE GREAT LAKES. AS OF 2 AM...SURFACE OBS AND DUAL POL RADAR
SHOWED THE RAIN/SNOW LINE FROM JUST WEST OF EAU CLAIRE WISCONSIN
DOWN TO WINONA MINNESOTA AND DECORAH IOWA. THE TRANSITION TO LIGHT
SNOW WILL BE RATHER BRIEF AND THEREFORE ANY SNOW ACCUMULATIONS
WILL BE ON THE LIGHT SIDE. EARLIER RUNS OF THE RAP HAD SHOWN THE
POSSIBILITY OF SOME FREEZING DRIZZLE OCCURRING AS THE SNOW CAME TO
AN END...BUT OBSERVATIONS/RADAR UPSTREAM IS NOT SHOWING ANY OF
THIS. DENSE FOG FORMED ACROSS MUCH OF THE REGION OVERNIGHT AS A
RESULT OF HIGH LOW LEVEL MOISTURE DUE TO RECENT RAIN AND SNOW MELT
ALONG WITH THE CORE OF A SURFACE LOW OVERHEAD WHICH PROVIDED
LIGHT TO CALM WINDS. AS THE COLD FRONT EXTENDING SOUTH FROM THE
LOW MOVES THROUGH...WINDS WILL PICK UP AND THE DENSE FOG WILL MIX
OUT WITH VISIBILITY IMPROVING. WITH VISIBILITY STILL LESS THAN A
QUARTER MILE IN NORTH CENTRAL WISCONSIN...WILL LET THE ADVISORY
ROLL FOR NOW WITH IT EXPIRING AT 6 AM...BUT MAY BE ABLE TO CLEAR
IT EARLY.
NOT THE CLEAREST OF WEATHER PATTERNS EXPECTED THROUGH THE NEXT FEW
DAYS WITH SUBTLE SYSTEMS MOVING INTO THE REGION THROUGH THE
SOUTHWEST-WESTERLY FLOW ALOFT. A WEAK MID LEVEL TROUGH WILL MOVE
THROUGH TODAY...BUT WILL ONLY ADD CLOUD COVER TO THE REGION.
16.00Z NAM/GFS SOUNDINGS SHOW THAT THE FORCING IS NOT VERY STRONG
AND THE DRY LAYER IS TOO DEEP FOR SEEDER FEEDER TO PRODUCE SOME
SNOW. A SURFACE RIDGE OF HIGH PRESSURE WILL THEN MOVE THROUGH THE
REGION TONIGHT INTO MONDAY BEFORE THE NEXT SYSTEM TAKES SHAPE IN
THE NORTHERN PLAINS. MUCH OF THE FORCING FOR THIS SYSTEM WILL BE
FROM THE LOW LEVEL WARM AIR ADVECTION...BUT THERE ALSO IS A MID
LEVEL TROUGH THAT ROTATES NORTHWARD INTO SOUTHERN CANADA OVER THE
SAME TIME FRAME. THE 16.00Z ECMWF IS THE STRONGEST WITH HAVING A
SURFACE LOW MOVE THROUGH...BUT OVERALL QPF REMAINS ON THE LIGHT
SIDE AT LESS THAN A TENTH OF AN INCH. PRECIPITATION TYPE WILL
MAINLY BE LIGHT SNOW WITH ANY ACCUMULATIONS LIKELY LESS THAN AN
INCH.
.LONG TERM...WEDNESDAY THROUGH SATURDAY
305 AM CST SUN DEC 16 2012
THE FOCUS FROM MID WEEK INTO NEXT WEEKEND CONTINUES TO BE WITH THE
POTENTIAL FOR A WINTER STORM WEDNESDAY NIGHT INTO THURSDAY. WHILE
THE SUITE OF 16.00Z GUIDANCE STILL ADVERTISES THIS DEEPENING
SURFACE LOW MOVING INTO SOUTHERN LAKE MICHIGAN BY THURSDAY
MORNING...THE TREND IS FOR THE MAJOR IMPACTS FROM THIS SYSTEM TO
BE MORE SO FELT TO THE SOUTH AND EAST OF THE FORECAST AREA. THE
FURTHER EAST THAT THIS SYSTEM CONTINUES TO MOVE...THE LOWER OUR
CHANCES BECOME OF SEEING THE HEAVIEST SNOW BAND OCCUR IN THE
FORECAST AREA. BASED ON 16.00Z GUIDANCE...THE WESTERN EDGE OF THE
SNOW APPEARS TO RUN FROM CENTRAL IOWA THROUGH SOUTHEAST MINNESOTA
AND NORTHWEST WISCONSIN. WHILE THE HEAVIEST SNOW BAND MAY BE TO THE
EAST OF THE FORECAST AREA...THE CHANCES FOR SNOW ACROSS THE REGION
STILL LOOK GOOD...SO HAVE BUMPED UP THE PRECIPITATION PROBABILITIES
WEDNESDAY NIGHT INTO THURSDAY. THIS SYSTEM IS CURRENTLY UP NEAR
THE ALEUTIAN ISLANDS WEST OF ALASKA AND WILL BE INTO CALIFORNIA BY
TUESDAY WHICH IS WHEN WE SHOULD HAVE A BETTER HANDLE ON THE
SYSTEMS TRACK.
BEHIND THIS SYSTEM...COLDER AIR WILL GET PULLED DOWN FROM SOUTHERN
CANADA...BUT IT APPEARS TO BE A FAIRLY SHORT LIVED COLD BURST
BEFORE LOW LEVEL WARM AIR ADVECTION STRENGTHENS OUT OF THE
SOUTHWEST ON SATURDAY. DUE TO THIS...HAVE TRENDED SLIGHTLY WARMER
FOR TEMPERATURES INTO THE WEEKEND.
&&
.AVIATION...THIS AFTERNOON THROUGH MONDAY
1200 PM CST SUN DEC 16 2012
MVFR/IFR CIGS/VSBYS WILL PERSIST ACROSS MUCH OF THE AREA THRU
TONIGHT AND MONDAY. CONSIDERABLE MOISTURE REMAINS TRAPPED ACROSS THE
REGION...IN/UNDER A SFC-800MB INVERSION. AREA SOUNDINGS SHOW THIS
MOISTURE TO BE SOME 3K-4K FT DEEP OVER MUCH OF MN/IA/WI. WITH WEAK
GRADIENTS AND A WEAK RIDGE OF HIGH PRESSURE TO BUILD OVER THE AREA
TONIGHT...LITTLE IN THE WAY OF ADVECTION LOOKS TO OCCUR PLUS THERE
IS PLENTY OF MOISTURE UPSTREAM OVER THE DAKOTAS/NORTHERN MN. THE
HIGH HOLDS THE INVERSION IN PLACE AS WELL. THUS...CONTINUED IFR
CIGS/VSBYS AT KRST THRU THE TAF PERIOD. KLSE A LITTLE BETTER BEING
IN THE VALLEY WITH CIGS AROUND 1K FT AND VFR OR MVFR VSBYS. THE
STRATUS BLANKET AND SOME WEAK NORTHWEST GRADIENT FLOW SHOULD KEEP
THE FOG FROM BECOMING DENSE AGAIN TONIGHT.
ANY IMPROVEMENT MONDAY LOOKS TO BE SLOW WITH WARM ADVECTION AND AN
INCREASE OF MOISTURE SPREADING INTO THE AREA AHEAD OF A WEAK
SHORTWAVE TROUGH MOVING ACROSS THE UPPER MIDWEST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
541 AM CST SUN DEC 16 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM....HALBACH
AVIATION.....RRS