Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/16/13
AREA FORECAST DISCUSSION
NWS ALBANY NY
715 PM EST SUN DEC 15 2013
.SYNOPSIS...
THE WINTER STORM THAT BROUGHT SIGNIFICANT SNOW TO THE REGION IS NOW
OVER THE CANADIAN MARITIMES AND CONTINUES TO MOVE NORTHEAST. IN ITS
WAKE...A BRIEF PERIOD OF LAKE EFFECT ACTIVITY IS EXPECTED WHICH MAY
BRING SOME ADDITIONAL LIGHT SNOW SHOWERS TO THE ADIRONDACKS...
CATSKILLS AND MOHAWK VALLEY TONIGHT. A RIDGE OF HIGH PRESSURE WILL
BRIEFLY BUILD IN FOR MONDAY AND MONDAY NIGHT...BEFORE THE NEXT STORM
SYSTEM MOVES IN WITH ADDITIONAL SNOW FOR TUESDAY AND TUESDAY NIGHT.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 715 PM EST...A SECONDARY COLD FRONT/ARCTIC BOUNDARY WAS
POSITIONED JUST NORTH OF THE AREA EARLY THIS EVENING. TEMPS BEHIND
THIS BOUNDARY ARE ONLY IN THE SINGLE DIGITS AND TEENS...WITH 20S
AHEAD OF IT COVERING MUCH OF OUR AREA AT THIS HOUR. SOME LAKE
ENHANCED SNOW SHOWERS HAVE DEVELOPED OVER WESTERN AND CENTRAL
NY...WITH CONVERGENCE ALONG THE FRONT FOCUSING THE MOISTURE. LOCAL
HIRES WRF AND HRRR DEPICTING SOME LAKE ENHANCED SNOW BANDS WILL
MOVE ACROSS THE SOUTHWEST ADIRONDACKS AND WESTERN/CENTRAL MOHAWK
VALLEY LATER THIS EVENING. THESE BANDS WILL BE TRANSITORY AND TIED
TO THE ARCTIC FRONT SWEEPING THROUGH...SO NO HEADLINES EXPECTED
FOR SNOW. SNOW ACCUMULATIONS AND POPS WERE RAISED SLIGHTLY IN
THESE AREAS TO MENTION 50-60 PERCENT CHANCE OF MEASURABLE SNOW
ACROSS A LARGER AREA...WITH ACCUMULATIONS GENERALLY 1 TO 3 INCHES
IN SOME SPOTS...ESPECIALLY SOUTHERN HERKIMER COUNTY. OUTSIDE OF
THE LAKE BANDS...ONLY ISOLATED TO WIDELY SCATTERED SNOW SHOWERS
ARE EXPECTED.
WIND CHILL ADVISORY CONTINUES FOR NORTHERN HERKIMER AND HAMILTON
COUNTIES FROM 1 AM TONIGHT THROUGH 10 AM MONDAY. CURRENT TEMP AND
WIND FORECASTS FOR THAT AREA SUPPORT WIND CHILL READINGS IN THE 20
TO 25 DEGREE BELOW ZERO RANGE DURING THAT TIME PERIOD.
GUSTY WESTERLY WINDS ASSOCIATED WITH THE LOW OVER THE CANADIAN
MARITIMES HAVE DECREASED THIS EVENING...HOWEVER WIND SPEEDS ARE
FORECAST TO INCREASE BEHIND THE COLD FRONT LATE TONIGHT. LOWS
WILL BE NEAR ZERO TO 10 BELOW ZERO OVER THE ADIRONDACK ZONES...AND
ABOUT 0 TO 15 DEGREES ABOVE ZERO ELSEWHERE.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
ANY LINGERING LAKE EFFECT WILL BE ORIENTED TOWARD THE EASTERN
CATSKILLS LATE MONDAY AFTN WITH ONLY SLIGHT OR LOW CHANCE POPS
FORECAST THERE...AND DRY ELSEWHERE. HIGHS MONDAY WILL RANGE FROM 5
TO 25 DEGREES.
THE WEAK HIGH PRESSURE SYSTEM WILL BE CENTERED OVER THE REGION EARLY
MONDAY NIGHT...AS MOISTURE ASSOCIATED WITH THE NEXT WAVE APPROACHES
FROM THE WEST. THIS WILL RESULT IN A WIDE RANGE OF POSSIBLE TEMP
CONDITIONS FOR MONDAY NIGHT. WITH A FRESH AND DEEP SNOW COVER NOW ON
THE GROUND...TEMPS COULD PLUMMET DURING THE EVENING WITH MOST
LOCATIONS GETTING TO ZERO OR BELOW. ON THE OTHER HAND...IF THE
CLOUDS ARRIVE FAST ENOUGH THEN TEMPS WILL REMAIN ABOVE ZERO IN MOST
LOCATIONS. MAV MOS TEMPS SUPPORT THE FIRST SCENARIO...WHILE THE NAM
MOS TEMPS THE SECOND. FOR NOW HAVE FORECAST BETWEEN THE MAV/MET MOS
NUMBERS...BUT CLOSER TO THE MAV MOS.
ON TUESDAY...THE FIRST IN A SERIES IF SHORT WAVE TROFS WILL PASS BY
TO OUR SOUTH AND WILL PRODUCE THE LIKELIHOOD OF AT LEAST SOME LIGHT
SNOW ACROSS THE REGION. THE TIMING OF THE DEVELOPMENT OF A SURFACE
LOW ALONG THE NJ COAST WILL BE A BIG FACTOR AS TO WHETHER WINTER
WEATHER ADVISORIES MAY BE NEEDED FOR TUESDAY. HAVE FORECAST LIKELY
POPS IN ALL AREAS TUESDAY. HIGHS TUESDAY WILL BE IN THE UPPER TEENS
AND 20S.
FOR TUESDAY NIGHT...A WEAKER TROF WILL MOVE THROUGH DURING THE NIGHT
WITH MAINLY SCT SNOW SHOWERS EXPECTED. LOWS WILL BE IN THE UPPER
SINGLE NUMBERS AND TEENS.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THIS WILL BE A PERIOD STARTING OFF MAINLY DRY AND THEN TRANSGRESSING
INTO AN UNSETTLED REGIME. WANING LAKE-EFFECT SNOWS ACROSS PORTIONS
OF THE WESTERN ADIRONDACKS AND MOHAWK VALLEY WILL BE THE ONLY FLY IN
THE OINTMENT AT MID-WEEK...BUT LOW PRESSURE TRACKING ACROSS THE
GREAT LAKES WILL BRING WINTRY WEATHER BACK TO THE ENTIRE REGION AT
THE END OF THE WORK WEEK. IF PRECIPITATION STARTS EARLY ON
FRIDAY...IT WILL BE IN THE FORM OF SNOW SHOWERS TRIGGERED AHEAD OF A
COLD FRONT. RAPID WARMING AHEAD OF THE FRONT IS EXPECTED TO ASSURE
ALL THE PRECIPITATION WILL BE RAIN SHOWERS BY EARLY AFTERNOON EXCEPT
FOR THE HIGHEST PEAKS OF THE ADIRONDACKS. BEHIND THE COLD FRONT
FRIDAY NIGHT...THE PRECIPITATION IS EXPECTED TO TRANSITION BACK TO
SNOW SHOWERS.
WHATEVER REPRIEVE THERE IS FROM THE PRECIPITATION ON SATURDAY WILL
BE BRIEF AS THE COLD FRONT STALLS JUST TO OUR SOUTH...AND LOW
PRESSURE DEVELOPS ALONG IT OVER THE OHIO VALLEY AND TRACKS UP TO
WESTERN NEW YORK BY SUNDAY. THE RESULT WILL BE MIXED WINTRY
PRECIPITATION MAINLY FROM THE CAPITAL REGION ON SOUTH...AND PURE
SNOW TO THE NORTH. THE LOW WILL COMBINE FORCES WITH AN ALBERTA-TYPE
CLIPPER...PROLONGING THE WINTRY ACTIVITY WELL INTO SUNDAY.
HIGH TEMPERATURES ON WEDNESDAY WILL RANGE FROM THE LOWER 20S TO MID
30S...WITH SLIGHTLY MILDER READINGS POSSIBLE FOR THURSDAY. FRIDAY
WILL BE THE BIG WARM-UP WITH HIGHS MOSTLY FROM THE UPPER 30S TO MID
40S. THEN SATURDAY AND SUNDAY HIGHS WILL BE FROM THE MID OR UPPER
20S NORTH...TO THE LOWER OR MID 40S SOUTH IN CLOSER PROXIMITY TO THE
STALLED-OUT FRONT. LOWS WILL BE FROM AROUND 10 DEGREES TO THE MID
TEENS WEDNESDAY NIGHT...IN THE 20S THURSDAY NIGHT...AND FROM THE
UPPER TEENS TO MID 30S FRIDAY NIGHT...WITH SLIGHTLY COLDER READINGS
FOR SATURDAY NIGHT. NORMAL HIGHS IN ALBANY DURING THE EXTENDED
PERIOD ARE IN THE MID 30S...WITH NORMAL LOWS AROUND 20 DEGREES.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
VFR CONDITIONS EXPECTED THROUGH THE PERIOD ENDING 00Z TUESDAY FOR
THE TERMINALS. AN ARCTIC COLD FRONT WILL PASS THROUGH LATE
TONIGHT...WHICH WILL RESULT IN ONLY A SLIGHT CHANCE OF SNOW
SHOWERS. COVERAGE NOT EXPECTED TO BE GREAT ENOUGH TO EXPLICITLY
MENTION IN TAFS AT THIS TIME. CIGS SHOULD GENERALLY BE BROKEN
AROUND 3500-4000 FT AGL. SKIES WILL CLEAR MONDAY AFTERNOON AS
DRIER AIR WORKS IN.
WEST-NORTHWEST WINDS WILL INCREASE LATE TONIGHT INTO MONDAY
MORNING IN WAKE OF THE ARCTIC FRONT TO AROUND 10-15 KT WITH
OCCASIONAL GUSTS OF 20-25 KT ESPECIALLY AT KALB/KPSF.
OUTLOOK...
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHSN.
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUESDAY NIGHT TO WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY TO THURSDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF
SHRA...SHSN.
FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
&&
.HYDROLOGY...
NO HYDRO RELATED CONCERNS ARE EXPECTED THE NEXT 5 DAYS.
THE NEXT CLIPPER SYSTEM APPROACHES FOR TUESDAY INTO TUESDAY
NIGHT. AT THIS TIME...ALL SNOW IS EXPECTED TO FALL WITH WATER
EQUIVALENTS EXPECTED TO BE MUCH LESS THAN THE SYSTEM THAT JUST
IMPACTED THE REGION OVER THE WEEKEND.
THEREAFTER...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE WILL
CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND
PARTICULARLY LAKES THROUGH MID WEEK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...WIND CHILL ADVISORY FROM 1 AM TO 10 AM EST MONDAY FOR NYZ032-
033.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...GJM
NEAR TERM...GJM/JPV
SHORT TERM...GJM
LONG TERM...ELH
AVIATION...JPV
HYDROLOGY...BGM/JPV
AREA FORECAST DISCUSSION
NWS ALBANY NY
126 PM EST SAT DEC 14 2013
.SYNOPSIS...
ARCTIC HIGH PRESSURE SITUATED ACROSS THE SAINT LAWRENCE VALLEY HAS
USHERED IN A VERY COLD AIR MASS INTO THE REGION. A WINTER STORM
TAKING SHAPE ACROSS THE OHIO VALLEY WILL TRACK TOWARD NEW ENGLAND
TONIGHT. THIS WILL SPREAD ACCUMULATING SNOW ACROSS THE REGION. THE
STORM WILL DEPART THE REGION BY SUNDAY AFTERNOON. EVEN COLDER AIR
WILL SURGE INTO THE REGION BEHIND THIS STORM ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1230 PM...NO CHANGES MADE TO THIS PART OF THE FORECAST...BUT
CHANGES MADE TO THE SHORT TERM SECTION.
.PREVIOUS DISCUSSION...
INCREASED POPS ACROSS THE SOUTHERN PORTION OF THE FORECAST AREA.
LIGHT SNOW IS OCCURRING ACROSS THE SOUTHEASTERN CATSKILLS...MID
HUDSON VALLEY AND LITCHFIELD COUNTY. RADAR RETURNS LOOK WEAK HOWEVER
METARS SHOW VISIBILITIES UNDER 3 MILES AND SOME UNDER 1 MILE.
ALSO ADJUSTED POPS SOME AS THE DAY PROGRESSES BRINGING CHANCES FOR
SNOW NORTHWARD THROUGH DAY. LATEST 06Z GUIDANCE AND HOURLY
RUC/HRRR CONTINUE ALONG THE SAME FORECAST THOUGHTS WITH WAA
ISENTROPIC LIFT EVOLVING ALONG A TIGHTENING BAROCLINIC ZONE ALONG
AND JUST NORTH OF THE NY STATE LINE. QPF/S CONTINUE TO SHOW A
SLIGHT INCREASE FROM PREVIOUS RUNS SO WE MADE SLIGHT ADJUSTMENTS
TO THE SNOWFALL FORECAST TODAY.
H2O VAPOR LOOP REVEALS OUR MAIN INGREDIENT FOR OUR WINTER STORM
WAS MOVING INTO THE TENNESSEE VALLEY. A STRENGTHENING UPPER JET IS
UNDERWAY ACROSS THE SOUTHERN CONUS PER SATELLITE WIND ESTIMATES
AND HOURLY RUC ANALYSIS WITH ANOTHER UPPER JET SEGMENT ACROSS THE
UPPER GREAT LAKES REGION. THIS NORTHERN PORTION OF THE JET IS
EXPECTED TO REMAIN CYCLONIC IN NATURE WHICH SUGGESTS THIS UPPER
LOW MAY TRACK A LITTLE FURTHER WEST AND HANGING ONTO THE INITIAL
SURFACE LOW LONGER BEFORE THE TRANSFER OCCURS OFF THE MID ATLANTIC
COAST. BROAD ISENTROPIC LIFT IN ADVANCE OF THESE FEATURES WAS
UNDERWAY ACROSS THE NY/PA BORDER AS BAROCLINICITY WAS INCREASING
JUST NORTH OF THE ARCTIC BOUNDARY. PER EXPERIMENTAL REFLECTIVITY
FORECASTS FROM A VARIETY OF MESOSCALE MODELS...ALONG WITH THE DRY
AIR IN PLACE...IT MAY TAKE MOST OF THE MORNING TO SATURATE THE
LOWER LEVELS FOR SNOW TO REACH THE GROUND /VIRGA/ NORTH OF I90 AS
LOW LEVEL AGEOSTROPIC FLOW REMAINS IN PLACE /MAGNITUDE IS NOT THAT
STRONG BUT IS VERY PERSISTENT/. USED A BLENDED APPROACH FOR HIGH
TEMPERATURES TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
WINTER STORM WARNING IN EFFECT FOR THE ENTIRE REGION...
AS OF 1230 PM...THE 12Z NAM AND GFS MODEL RUNS TRACK THE LOW FURTHER
NORTH WITH THE TRACK NOW FORECAST TO GO RIGHT OVER LONG ISLAND. THIS
SHOULD RESULT IN ADDITIONAL MID LEVEL WARMING SO HAVE ADJUSTED THE
WEATHER GRIDS TO INCLUDE MORE FREEZING RAIN AND SLEET AFTER 06Z
TONIGHT AND HAVE ALSO PUSHED THE NORTHERN EXTENT OF THE MIXED PCPN
ALL THE WAY INTO THE CENTRAL CATSKILLS...THE SOUTHEAST PART OF THE
CAPITAL DISTRICT...THROUGH ALL OF BERKSHIRE COUNTY AND JUST ACROSS
THE BORDER INTO EXTREME SOUTHERN VERMONT. THIS HAS RESULTED IN ONE
TO FOUR INCH REDUCTIONS IN THE AMOUNTS OF SNOW FORECAST IN THESE
AREAS...WITH THE GREATEST REDUCTIONS OCCURRING OVER LITCHFIELD...
DUTCHESS AND EASTERN ULSTER COUNTIES. IT HAS ALSO EXPANDED THE AREA
WHERE ICING WILL OCCUR. DESPITE THE SNOW REDUCTIONS...STILL ENOUGH
SNOW WITH ENOUGH ICING IS FORECAST TO CONTINUE THE WINTER STORM
WARNINGS IN ALL AREAS...INCLUDING THE SOUTHERN ZONES.
.PREVIOUS DISCUSSION...
PREVIOUS DISCUSSIONS HAVE DONE AN EXCELLENT JOB WITH THE
METEOROLOGICAL PARAMETERS SETTING UP FOR THIS FIRST WIDESPREAD
SIGNIFICANT WINTER EVENT FOR THE REGION. 00Z GUIDANCE ALONG WITH THE
RECENT ARRIVAL OF THE 06Z NAM/GFS CONTINUE TO INCREASE QPF AMOUNTS
ALONG WITH ENHANCED FGEN BANDS SEEN IN THE H850-H700 LAYER PER
PREVIOUS CSTAR RESEARCH. THESE BANDS ARE PROGGED TO BE A LITTLE
FURTHER NORTH AND PER COORDINATION FROM WPC AND SURROUNDING
WFOS...WE WILL UPGRADE THE ADVISORY AREA AND EXTEND THE WARNING
ACROSS THE ENTIRE CWFA. IT WILL BE CLOSE PER THE DEFINITION OF 7"
IN 12HRS OR 9" IN 24HRS BUT WITH A HIGH IMPACT WIDESPREAD EVENT
THE WARNING WAS EXPANDED. AS WARM ADVECTION OCCURS IN THE THERMAL
PROFILES...SOME OF THE PRECIP ACROSS DUTCHESS AND LITCHFIELD
COUNTIES WILL MIX WITH SLEET AND FREEZING RAIN LATE TONIGHT. ICE
ACCUMULATIONS UP TO TWO TENTHS OF AN INCH ARE POSSIBLE BEFORE THE
WARM AIR AT THE SURFACE ARRIVES TO RESULT IN A CHANGEOVER TO
MAINLY RAIN/RAIN SHOWERS LATER SUNDAY MORNING. SO TEMPERATURES
WILL BE STEADY TO SLOWLY RISING OVERNIGHT AS WE WILL SHOW A NON-
DIURNAL TEMPERATURE TREND OVERNIGHT.
THE OTHER COMPLICATED FACTOR TO THIS WILL BE TRANSITIONING
SNOW TO LIQUID RATIOS AS WE SHOULD INITIALLY BE RATHER HIGH WITH
15:1 RATIO THEN GRADUALLY DROPPING TOWARD CLIMATOLOGY OF 12:1 FOR
MOST OF THE REGION AND EVENTUALLY TOWARD 10:1 TOWARD SUNRISE
SUNDAY. THE CROSS SECTIONS NOW REVEAL WE WILL INDEED SEE THE BEST
LIFT OCCUR IN THE BEST DENDRITIC SNOW GROWTH REGION WHICH ALONG
WITH FGEN BANDS TO ENHANCE SNOWFALL RATES. IN FACT...D-THETA/DZ
SUGGESTS THE SMALL POTENTIAL FOR CONVECTIVE ELEMENTS BETWEEN 06Z-
12Z SUNDAY AND AS THE SECONDARY LOW DEVELOPS OFF THE NJ
COAST...THE DUCT FUNCTION POINTS TOWARD THE POTENTIAL FOR A
GRAVITY WAVE/S/.
PRECIP SHADOW IS INDEED STILL PLAUSIBLE TOO AS LOW-MID LEVEL EAST-
SOUTHEAST WINDS INCREASE SUGGESTING PRECIP SHADOW DOWNWIND OF THE
BERKS-TACONICS AND THE GREENS INTO PORTIONS OF WASHINGTON COUNTY.
THIS STORM DEEPENS SUNDAY AS IT TRACKS THROUGH THE SOUTHERN
PORTIONS OF THE GULF OF MAINE WITH DEFORMATION SNOW AXIS ACROSS
PORTIONS OF THE DACKS. WIND GUSTS WILL LIKELY INCREASE TOO WHICH
WILL RESULT IN SOME BLOWING AND DRIFTING OF THE SNOW.
FURTHERMORE...WIND CHILLS WILL LIKELY DIP WELL BELOW ZERO ACROSS
THE DACKS AS WE MAY NEED HEADLINES FOR THIS IN FUTURE FORECASTS.
SNOW WILL TAPER OFF THROUGH THE DAYLIGHT HOURS SUNDAY WITH SOME
LAKE RESPONSE SUNDAY NIGHT INTO PORTIONS OF THE DACKS...WESTERN
MOHAWK VALLEY AND CATSKILLS.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
BEHIND THE DEPARTING WINTER STORM...HIGH PRESSURE WILL MOVE OVER
THE REGION FOR MONDAY. WITH A COLD NW FLOW IN PLACE...MAX TEMPS
WILL BE BELOW NORMAL...WITH TEENS TO MID 20S ACROSS THE REGION.
VERY COLD TEMP WILL CONTINUE INTO MONDAY NIGHT WITH SINGLE DIGITS
OVER MUCH OF THE AREA. SOME BELOW ZERO READINGS WILL OCCUR ACROSS
THE ADIRONDACKS AND GREEN MOUNTAINS.
CLOUDS WILL BEGIN TO INCREASE LATE MONDAY NIGHT...WITH A SLIGHT CHC
FOR SOME SNOW SHOWERS...AS A CLIPPER SYSTEM BEGINS TO APPROACH FROM
THE GREAT LAKES. THIS WEAK SYSTEM WILL BE QUITE MOISTURE STARVED.
STILL...THERE IS A CHANCE FOR SOME LIGHT SNOW ACROSS THE REGION FOR
TUESDAY INTO TUESDAY NIGHT AS THIS SYSTEM TRACKS ACROSS THE AREA.
ANY QPF LOOKS RATHER LIGHT...AND SNOWFALL WILL ONLY BE AN INCH OR
TWO FOR MOST PLACES. MAX TEMPS WILL CONTINUE TO BE CHILLY ON TUESDAY
WITH 20S OVER MUCH OF THE AREA...AND TEENS TO LOW 20S FOR TUESDAY
NIGHT.
SOME LAKE EFFECT SNOW WILL OCCUR ACROSS THE WESTERN ADIRONDACKS AND
WESTERN MOHAWK VALLEY BEHIND THIS CLIPPER SYSTEM FOR WED INTO WED
NIGHT. OTHERWISE...IT LOOKS DRY OVER MUCH OF THE AREA. TEMPS ON WED
WILL BE A LITTLE WARMER THAN RECENT DAYS...WITH MID 20S TO MID 30S.
HOWEVER...A REINFORCING SHOT OF COLD AIR LOOKS TO ARRIVE ON WED
NIGHT...WITH TEENS FOR THE AREA...AND TEMPS BACK INTO THE 20S FOR
THURSDAY.
THIS COLD SHOT LOOKS TO BE SHORT LIVED...AS HIGH PRESSURE QUICKLY
PASSES OVER THE AREA...AND THE PATTERN BEGINS TO SHIFT SOMEWHAT.
WHILE IT WILL BE DRY FOR THURSDAY...THE OVERALL FLOW STARTS TO
BECOME MORE OUT OF THE SW BOTH AT THE LOW LEVELS AND ALOFT. THIS
WILL TRANSPORT MUCH WARMER AND MORE MOIST AIR INTO THE REGION FOR
THE LATE WEEK PERIOD. MAX TEMPS LOOK TO REACH INTO THE 40S FOR
VALLEY AREAS BY FRIDAY. ALTHOUGH IT/S STILL RATHER FAR OUT IN
TIME...AN APPROACHING SLOW MOVING FRONTAL BOUNDARY LOOKS TO BRING A
PERIOD OF PLAIN RAIN TO THE REGION FOR LATE IN THE WEEK AND INTO THE
WEEKEND ACROSS THE ENTIRE REGION...EVEN THE HIGHER TERRAIN
AREAS...WITH A RETURN TO ABOVE NORMAL TEMPS EXPECTED INTO THE
WEEKEND.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
A STORM SYSTEM OVER THE OHIO VALLEY WILL CONTINUE TO MOVE
NORTHEASTWARD AS WE HEAD INTO THE EVENING AS THE ARCTIC HIGH
CONTINUES TO RETREAT NORTHWARD. SECONDARY DEVELOPMENT IS OCCURRING
ALONG THE MID ATLANTIC COAST EVIDENT BY PRESSURE FALLS. THE COASTAL
LOW WILL BECOME THE PRIMARY LOW AS WE HEAD THROUGH THE OVERNIGHT
HOURS AS IT TRACKS NORTHEAST AND STRENGTHENS. THIS LOW IS FORECAST
TO CROSS OVER EASTERN LONG ISLAND AND CAPE COD SUNDAY MORNING.
LIGHT SNOW WILL CONTINUE TO SPREAD NORTHWARD WITH MVFR-IFR
CONDITIONS MAINLY DUE TO VISIBILITIES. THE SNOW WILL BECOME
HEAVIER AS WE HEAD INTO THE EVENING HOURS AND THE LOW LEVEL JET
APPROACHES AND MOVES INTO THE REGION. CONDITIONS WILL DETERIORATE
TO IFR THEN TO LIFR OVERNIGHT. BASED ON THE TRACK OF THE COASTAL
LOW SOME WARMER AIR WILL WORK ALOFT RESULTING IN SLEET MIXING IN
WITH THE SNOW AT KPSF AND EVEN AT KALB FOR A BIT BEFORE THE
PRECIPITATION BEGINS TO TAPER OFF. HOWEVER AT KPOU A TRANSITION TO
SLEET AND EVENTUALLY TO FREEZING RAIN IS EXPECTED MAINLY AFTER
MIDNIGHT.
CONDITIONS WILL BEGIN TO IMPROVE SUNDAY MORNING AFTER SUNRISE AS LOW
MOVES UP THE NEW ENGLAND COAST AND PRECIPITATION TAPERS OFF. EXPECTING
WIDESPREAD MVFR MAINLY DUE TO CEILING BY AFTERNOON.
OUTLOOK...
SUN: HIGH OPERATIONAL IMPACT. SN.
SUN NIGHT-MON: LOW OPERATIONAL IMPACT. BREEZY.
MON NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUE-TUE NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SN.
WED: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
NO HYDRO RELATED CONCERNS ARE EXPECTED THE NEXT 5 DAYS.
QPF FROM THIS UPCOMING EVENT WILL RANGE FROM ONE HALF INCH TO ONE
AND ONE QUARTER OF AN INCH WITH THOSE HIGHER VALUES ACROSS THE
TERRAIN INTO THE CATSKILLS...SOUTHERN GREENS AND PORTIONS OF THE
DACKS. MOST OF THIS WILL FALL IN THE FORM OF SNOW WITH THE
EXCEPTION ACROSS DUTCHESS AND LITCHFIELD COUNTIES WHERE A WINTRY
MIXTURE AND PERHAPS A PERIOD OF RAIN MAY RESULT LATE SATURDAY
NIGHT INTO SUNDAY MORNING. ANY LIQUID PRECIP SHOULD RESULT WITHIN
BANK RISES.
THEREAFTER...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE WILL
CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND
PARTICULARLY LAKES THROUGH EARLY NEXT WEEK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR CTZ001-013.
NY...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR NYZ032-033-
038>043-047>054-058>061-063>066-082>084.
MA...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR MAZ001-025.
VT...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR VTZ013>015.
&&
$$
SYNOPSIS...BGM
NEAR TERM...IAA/BGM
SHORT TERM...BGM
LONG TERM...FRUGIS
AVIATION...IAA
HYDROLOGY...BGM
AREA FORECAST DISCUSSION
NWS ALBANY NY
110 PM EST SAT DEC 14 2013
.SYNOPSIS...
ARCTIC HIGH PRESSURE SITUATED ACROSS THE SAINT LAWRENCE VALLEY HAS
USHERED IN A VERY COLD AIR MASS INTO THE REGION. A WINTER STORM
TAKING SHAPE ACROSS THE OHIO VALLEY WILL TRACK TOWARD NEW ENGLAND
TONIGHT. THIS WILL SPREAD ACCUMULATING SNOW ACROSS THE REGION. THE
STORM WILL DEPART THE REGION BY SUNDAY AFTERNOON. EVEN COLDER AIR
WILL SURGE INTO THE REGION BEHIND THIS STORM ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1230 PM...NO CHANGES MADE TO THIS PART OF THE FORECAST...BUT
CHANGES MADE TO THE SHORT TERM SECTION.
.PREVIOUS DISCUSSION...
INCREASED POPS ACROSS THE SOUTHERN PORTION OF THE FORECAST AREA.
LIGHT SNOW IS OCCURRING ACROSS THE SOUTHEASTERN CATSKILLS...MID
HUDSON VALLEY AND LITCHFIELD COUNTY. RADAR RETURNS LOOK WEAK HOWEVER
METARS SHOW VISIBILITIES UNDER 3 MILES AND SOME UNDER 1 MILE.
ALSO ADJUSTED POPS SOME AS THE DAY PROGRESSES BRINGING CHANCES FOR
SNOW NORTHWARD THROUGH DAY. LATEST 06Z GUIDANCE AND HOURLY
RUC/HRRR CONTINUE ALONG THE SAME FORECAST THOUGHTS WITH WAA
ISENTROPIC LIFT EVOLVING ALONG A TIGHTENING BAROCLINIC ZONE ALONG
AND JUST NORTH OF THE NY STATE LINE. QPF/S CONTINUE TO SHOW A
SLIGHT INCREASE FROM PREVIOUS RUNS SO WE MADE SLIGHT ADJUSTMENTS
TO THE SNOWFALL FORECAST TODAY.
H2O VAPOR LOOP REVEALS OUR MAIN INGREDIENT FOR OUR WINTER STORM
WAS MOVING INTO THE TENNESSEE VALLEY. A STRENGTHENING UPPER JET IS
UNDERWAY ACROSS THE SOUTHERN CONUS PER SATELLITE WIND ESTIMATES
AND HOURLY RUC ANALYSIS WITH ANOTHER UPPER JET SEGMENT ACROSS THE
UPPER GREAT LAKES REGION. THIS NORTHERN PORTION OF THE JET IS
EXPECTED TO REMAIN CYCLONIC IN NATURE WHICH SUGGESTS THIS UPPER
LOW MAY TRACK A LITTLE FURTHER WEST AND HANGING ONTO THE INITIAL
SURFACE LOW LONGER BEFORE THE TRANSFER OCCURS OFF THE MID ATLANTIC
COAST. BROAD ISENTROPIC LIFT IN ADVANCE OF THESE FEATURES WAS
UNDERWAY ACROSS THE NY/PA BORDER AS BAROCLINICITY WAS INCREASING
JUST NORTH OF THE ARCTIC BOUNDARY. PER EXPERIMENTAL REFLECTIVITY
FORECASTS FROM A VARIETY OF MESOSCALE MODELS...ALONG WITH THE DRY
AIR IN PLACE...IT MAY TAKE MOST OF THE MORNING TO SATURATE THE
LOWER LEVELS FOR SNOW TO REACH THE GROUND /VIRGA/ NORTH OF I90 AS
LOW LEVEL AGEOSTROPIC FLOW REMAINS IN PLACE /MAGNITUDE IS NOT THAT
STRONG BUT IS VERY PERSISTENT/. USED A BLENDED APPROACH FOR HIGH
TEMPERATURES TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
WINTER STORM WARNING IN EFFECT FOR THE ENTIRE REGION...
AS OF 1230 PM...THE 12Z NAM AND GFS MODEL RUNS TRACK THE LOW FURTHER
NORTH WITH THE TRACK NOW FORECAST TO GO RIGHT OVER LONG ISLAND. THIS
SHOULD RESULT IN ADDITIONAL MID LEVEL WARMING SO HAVE ADJUSTED THE
WEATHER GRIDS TO INCLUDE MORE FREEZING RAIN AND SLEET AFTER 06Z
TONIGHT AND HAVE ALSO PUSHED THE NORTHERN EXTENT OF THE MIXED PCPN
ALL THE WAY INTO THE CENTRAL CATSKILLS...THE SOUTHEAST PART OF THE
CAPITAL DISTRICT...THROUGH ALL OF BERKSHIRE COUNTY AND JUST ACROSS
THE BORDER INTO EXTREME SOUTHERN VERMONT. THIS HAS RESULTED IN ONE
TO FOUR INCH REDUCTIONS IN THE AMOUNTS OF SNOW FORECAST IN THESE
AREAS...WITH THE GREATEST REDUCTIONS OCCURRING OVER LITCHFIELD...
DUTCHESS AND EASTERN ULSTER COUNTIES. IT HAS ALSO EXPANDED THE AREA
WHERE ICING WILL OCCUR. DESPITE THE SNOW REDUCTIONS...STILL ENOUGH
SNOW WITH ENOUGH ICING IS FORECAST TO CONTINUE THE WINTER STORM
WARNINGS IN ALL AREAS...INCLUDING THE SOUTHERN ZONES.
.PREVIOUS DISCUSSION...
PREVIOUS DISCUSSIONS HAVE DONE AN EXCELLENT JOB WITH THE
METEOROLOGICAL PARAMETERS SETTING UP FOR THIS FIRST WIDESPREAD
SIGNIFICANT WINTER EVENT FOR THE REGION. 00Z GUIDANCE ALONG WITH THE
RECENT ARRIVAL OF THE 06Z NAM/GFS CONTINUE TO INCREASE QPF AMOUNTS
ALONG WITH ENHANCED FGEN BANDS SEEN IN THE H850-H700 LAYER PER
PREVIOUS CSTAR RESEARCH. THESE BANDS ARE PROGGED TO BE A LITTLE
FURTHER NORTH AND PER COORDINATION FROM WPC AND SURROUNDING
WFOS...WE WILL UPGRADE THE ADVISORY AREA AND EXTEND THE WARNING
ACROSS THE ENTIRE CWFA. IT WILL BE CLOSE PER THE DEFINITION OF 7"
IN 12HRS OR 9" IN 24HRS BUT WITH A HIGH IMPACT WIDESPREAD EVENT
THE WARNING WAS EXPANDED. AS WARM ADVECTION OCCURS IN THE THERMAL
PROFILES...SOME OF THE PRECIP ACROSS DUTCHESS AND LITCHFIELD
COUNTIES WILL MIX WITH SLEET AND FREEZING RAIN LATE TONIGHT. ICE
ACCUMULATIONS UP TO TWO TENTHS OF AN INCH ARE POSSIBLE BEFORE THE
WARM AIR AT THE SURFACE ARRIVES TO RESULT IN A CHANGEOVER TO
MAINLY RAIN/RAIN SHOWERS LATER SUNDAY MORNING. SO TEMPERATURES
WILL BE STEADY TO SLOWLY RISING OVERNIGHT AS WE WILL SHOW A NON-
DIURNAL TEMPERATURE TREND OVERNIGHT.
THE OTHER COMPLICATED FACTOR TO THIS WILL BE TRANSITIONING
SNOW TO LIQUID RATIOS AS WE SHOULD INITIALLY BE RATHER HIGH WITH
15:1 RATIO THEN GRADUALLY DROPPING TOWARD CLIMATOLOGY OF 12:1 FOR
MOST OF THE REGION AND EVENTUALLY TOWARD 10:1 TOWARD SUNRISE
SUNDAY. THE CROSS SECTIONS NOW REVEAL WE WILL INDEED SEE THE BEST
LIFT OCCUR IN THE BEST DENDRITIC SNOW GROWTH REGION WHICH ALONG
WITH FGEN BANDS TO ENHANCE SNOWFALL RATES. IN FACT...D-THETA/DZ
SUGGESTS THE SMALL POTENTIAL FOR CONVECTIVE ELEMENTS BETWEEN 06Z-
12Z SUNDAY AND AS THE SECONDARY LOW DEVELOPS OFF THE NJ
COAST...THE DUCT FUNCTION POINTS TOWARD THE POTENTIAL FOR A
GRAVITY WAVE/S/.
PRECIP SHADOW IS INDEED STILL PLAUSIBLE TOO AS LOW-MID LEVEL EAST-
SOUTHEAST WINDS INCREASE SUGGESTING PRECIP SHADOW DOWNWIND OF THE
BERKS-TACONICS AND THE GREENS INTO PORTIONS OF WASHINGTON COUNTY.
THIS STORM DEEPENS SUNDAY AS IT TRACKS THROUGH THE SOUTHERN
PORTIONS OF THE GULF OF MAINE WITH DEFORMATION SNOW AXIS ACROSS
PORTIONS OF THE DACKS. WIND GUSTS WILL LIKELY INCREASE TOO WHICH
WILL RESULT IN SOME BLOWING AND DRIFTING OF THE SNOW.
FURTHERMORE...WIND CHILLS WILL LIKELY DIP WELL BELOW ZERO ACROSS
THE DACKS AS WE MAY NEED HEADLINES FOR THIS IN FUTURE FORECASTS.
SNOW WILL TAPER OFF THROUGH THE DAYLIGHT HOURS SUNDAY WITH SOME
LAKE RESPONSE SUNDAY NIGHT INTO PORTIONS OF THE DACKS...WESTERN
MOHAWK VALLEY AND CATSKILLS.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
BEHIND THE DEPARTING WINTER STORM...HIGH PRESSURE WILL MOVE OVER
THE REGION FOR MONDAY. WITH A COLD NW FLOW IN PLACE...MAX TEMPS
WILL BE BELOW NORMAL...WITH TEENS TO MID 20S ACROSS THE REGION.
VERY COLD TEMP WILL CONTINUE INTO MONDAY NIGHT WITH SINGLE DIGITS
OVER MUCH OF THE AREA. SOME BELOW ZERO READINGS WILL OCCUR ACROSS
THE ADIRONDACKS AND GREEN MOUNTAINS.
CLOUDS WILL BEGIN TO INCREASE LATE MONDAY NIGHT...WITH A SLIGHT CHC
FOR SOME SNOW SHOWERS...AS A CLIPPER SYSTEM BEGINS TO APPROACH FROM
THE GREAT LAKES. THIS WEAK SYSTEM WILL BE QUITE MOISTURE STARVED.
STILL...THERE IS A CHANCE FOR SOME LIGHT SNOW ACROSS THE REGION FOR
TUESDAY INTO TUESDAY NIGHT AS THIS SYSTEM TRACKS ACROSS THE AREA.
ANY QPF LOOKS RATHER LIGHT...AND SNOWFALL WILL ONLY BE AN INCH OR
TWO FOR MOST PLACES. MAX TEMPS WILL CONTINUE TO BE CHILLY ON TUESDAY
WITH 20S OVER MUCH OF THE AREA...AND TEENS TO LOW 20S FOR TUESDAY
NIGHT.
SOME LAKE EFFECT SNOW WILL OCCUR ACROSS THE WESTERN ADIRONDACKS AND
WESTERN MOHAWK VALLEY BEHIND THIS CLIPPER SYSTEM FOR WED INTO WED
NIGHT. OTHERWISE...IT LOOKS DRY OVER MUCH OF THE AREA. TEMPS ON WED
WILL BE A LITTLE WARMER THAN RECENT DAYS...WITH MID 20S TO MID 30S.
HOWEVER...A REINFORCING SHOT OF COLD AIR LOOKS TO ARRIVE ON WED
NIGHT...WITH TEENS FOR THE AREA...AND TEMPS BACK INTO THE 20S FOR
THURSDAY.
THIS COLD SHOT LOOKS TO BE SHORT LIVED...AS HIGH PRESSURE QUICKLY
PASSES OVER THE AREA...AND THE PATTERN BEGINS TO SHIFT SOMEWHAT.
WHILE IT WILL BE DRY FOR THURSDAY...THE OVERALL FLOW STARTS TO
BECOME MORE OUT OF THE SW BOTH AT THE LOW LEVELS AND ALOFT. THIS
WILL TRANSPORT MUCH WARMER AND MORE MOIST AIR INTO THE REGION FOR
THE LATE WEEK PERIOD. MAX TEMPS LOOK TO REACH INTO THE 40S FOR
VALLEY AREAS BY FRIDAY. ALTHOUGH IT/S STILL RATHER FAR OUT IN
TIME...AN APPROACHING SLOW MOVING FRONTAL BOUNDARY LOOKS TO BRING A
PERIOD OF PLAIN RAIN TO THE REGION FOR LATE IN THE WEEK AND INTO THE
WEEKEND ACROSS THE ENTIRE REGION...EVEN THE HIGHER TERRAIN
AREAS...WITH A RETURN TO ABOVE NORMAL TEMPS EXPECTED INTO THE
WEEKEND.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
A STORM SYSTEM WILL MOVE TOWARDS THE OHIO VALLEY TODAY AND REFORM
OFF THE JERSEY SHORE BY THIS EVENING. AS THIS STORM SYSTEM EVOLVES
AND MOVES TOWARDS THE AREA...LIGHT SNOW WILL CONTINUE TO SLOWLY
SPREAD NORTHWARD. SNOW HAS ALREADY BEGUN AT KPOU...AND SHOULD BEGIN
AT KPSF SOON...KALB BY ABOUT MID MORNING...AND KGFL BY LATE MORNING
OR SO. INITIALLY...THE DRY AIRMASS IN PLACE WILL ONLY ALLOW FOR
LIGHT SNOW AND MVFR CONDITIONS. AFTER ABOUT AN HOUR OR TWO...IFR
SNOW LOOKS FALL WITHIN PERIODS OF LIGHT SNOW. ALTHOUGH AT FIRST THE
SNOW MAY NOT BE STEADY AND FLYING CONDITIONS FLUCTUATE BETWEEN
IFR/MVFR...ALL SITES SHOULD BE SEEING PREDOMINATELY IFR SNOW BY
LATER THIS AFTN AS THE SNOW BEGINS TO BECOME MORE WIDESPREAD. WINDS
TODAY WILL BE N-NE AT AROUND 5 KTS.
AS THE STORM STRENGTHENS RAPIDLY OFF THE COAST...THE SNOW WILL PICK
UP IN INTENSITY BY LATE THIS EVENING AND INTO THE OVERNIGHT HOURS.
AT THIS POINT...LIFR CONDITIONS ARE POSSIBLE AS WELL...WHEN THE SNOW
WILL BE FALLING ITS HARDEST AND VV WILL BE QUITE LIMITED. VSBYS WILL
BE LESS THAN ONE MILE...AND PERHAPS AS LOW AS 1/4SM TO 1/2SM. THE
PRECIP WILL MIX WITH AND CHANGE TO SLEET/FREEZING RAIN AT KPOU AFTER
MIDNIGHT...BUT THE REMAINING SITES WILL STAY ALL SNOW. THE SNOW MAY
START TO DECREASE IN INTENSITY LATE TONIGHT FROM SOUTH TO NORTH AS
THE STORM BEGINS TO MOVE UP TOWARDS NEW ENGLAND...ALTHOUGH FLYING
CONDITIONS WILL REMAIN IFR THROUGH 12Z.
OUTLOOK...
SUN: HIGH OPERATIONAL IMPACT. SN.
SUN NIGHT-MON: LOW OPERATIONAL IMPACT. BREEZY.
MON NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUE-TUE NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SN.
WED: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
NO HYDRO RELATED CONCERNS ARE EXPECTED THE NEXT 5 DAYS.
QPF FROM THIS UPCOMING EVENT WILL RANGE FROM ONE HALF INCH TO ONE
AND ONE QUARTER OF AN INCH WITH THOSE HIGHER VALUES ACROSS THE
TERRAIN INTO THE CATSKILLS...SOUTHERN GREENS AND PORTIONS OF THE
DACKS. MOST OF THIS WILL FALL IN THE FORM OF SNOW WITH THE
EXCEPTION ACROSS DUTCHESS AND LITCHFIELD COUNTIES WHERE A WINTRY
MIXTURE AND PERHAPS A PERIOD OF RAIN MAY RESULT LATE SATURDAY
NIGHT INTO SUNDAY MORNING. ANY LIQUID PRECIP SHOULD RESULT WITHIN
BANK RISES.
THEREAFTER...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE WILL
CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND
PARTICULARLY LAKES THROUGH EARLY NEXT WEEK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR CTZ001-013.
NY...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR NYZ032-033-
038>043-047>054-058>061-063>066-082>084.
MA...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR MAZ001-025.
VT...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR VTZ013>015.
&&
$$
SYNOPSIS...GJM/BGM
NEAR TERM...GJM/IAA/BGM
SHORT TERM...GJM/BGM
LONG TERM...FRUGIS
AVIATION...IAA/FRUGIS
HYDROLOGY...BGM
AREA FORECAST DISCUSSION
NWS ALBANY NY
821 AM EST SAT DEC 14 2013
.SYNOPSIS...
ARCTIC HIGH PRESSURE SITUATED ACROSS THE SAINT LAWRENCE VALLEY
HAS USHERED IN A VERY COLD AND DRY AIR MASS INTO THE REGION.
MEANWHILE A COMPLEX WINTER STORM IS TAKING SHAPE ACROSS THE
CENTER OF THE NATION AND WILL TRACK TOWARD NEW ENGLAND TONIGHT.
THIS WILL SPREAD AN ACCUMULATING SNOW ACROSS MOST OF THE REGION.
THIS STORM WILL DEPART BY SUNDAY AFTERNOON WITH SLOW IMPROVEMENTS
TO OUR WEATHER EXPECTED.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
INCREASED POPS ACROSS THE SOUTHERN PORTION OF THE FORECAST AREA.
LIGHT SNOW IS OCCURRING ACROSS THE SOUTHEASTERN CATSKILLS...MID
HUDSON VALLEY AND LITCHFIELD COUNTY. RADAR RETURNS LOOK WEAK HOWEVER
METARS SHOW VISIBILITIES UNDER 3 MILES AND SOME UNDER 1 MILE.
ALSO ADJUSTED POPS SOME AS THE DAY PROGRESSES BRINGING CHANCES FOR
SNOW NORTHWARD THROUGH DAY. LATEST 06Z GUIDANCE AND HOURLY
RUC/HRRR CONTINUE ALONG THE SAME FORECAST THOUGHTS WITH WAA
ISENTROPIC LIFT EVOLVING ALONG A TIGHTENING BAROCLINIC ZONE ALONG
AND JUST NORTH OF THE NY STATE LINE. QPF/S CONTINUE TO SHOW A
SLIGHT INCREASE FROM PREVIOUS RUNS SO WE MADE SLIGHT ADJUSTMENTS
TO THE SNOWFALL FORECAST TODAY.
H2O VAPOR LOOP REVEALS OUR MAIN INGREDIENT FOR OUR WINTER STORM
WAS MOVING INTO THE TENNESSEE VALLEY. A STRENGTHENING UPPER JET IS
UNDERWAY ACROSS THE SOUTHERN CONUS PER SATELLITE WIND ESTIMATES
AND HOURLY RUC ANALYSIS WITH ANOTHER UPPER JET SEGMENT ACROSS THE
UPPER GREAT LAKES REGION. THIS NORTHERN PORTION OF THE JET IS
EXPECTED TO REMAIN CYCLONIC IN NATURE WHICH SUGGESTS THIS UPPER
LOW MAY TRACK A LITTLE FURTHER WEST AND HANGING ONTO THE INITIAL
SURFACE LOW LONGER BEFORE THE TRANSFER OCCURS OFF THE MID ATLANTIC
COAST. BROAD ISENTROPIC LIFT IN ADVANCE OF THESE FEATURES WAS
UNDERWAY ACROSS THE NY/PA BORDER AS BAROCLINICITY WAS INCREASING
JUST NORTH OF THE ARCTIC BOUNDARY. PER EXPERIMENTAL REFLECTIVITY
FORECASTS FROM A VARIETY OF MESOSCALE MODELS...ALONG WITH THE DRY
AIR IN PLACE...IT MAY TAKE MOST OF THE MORNING TO SATURATE THE
LOWER LEVELS FOR SNOW TO REACH THE GROUND /VIRGA/ NORTH OF I90 AS
LOW LEVEL AGEOSTROPIC FLOW REMAINS IN PLACE /MAGNITUDE IS NOT THAT
STRONG BUT IS VERY PERSISTENT/. USED A BLENDED APPROACH FOR HIGH
TEMPERATURES TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
WINTER STORM WARNING IN EFFECT FOR THE ENTIRE REGION...
PREVIOUS DISCUSSIONS HAVE DONE AN EXCELLENT JOB WITH THE
METEOROLOGICAL PARAMETERS SETTING UP FOR THIS FIRST WIDESPREAD
SIGNIFICANT WINTER EVENT FOR THE REGION. 00Z GUIDANCE ALONG WITH THE
RECENT ARRIVAL OF THE 06Z NAM/GFS CONTINUE TO INCREASE QPF AMOUNTS
ALONG WITH ENHANCED FGEN BANDS SEEN IN THE H850-H700 LAYER PER
PREVIOUS CSTAR RESEARCH. THESE BANDS ARE PROGGED TO BE A LITTLE
FURTHER NORTH AND PER COORDINATION FROM WPC AND SURROUNDING
WFOS...WE WILL UPGRADE THE ADVISORY AREA AND EXTEND THE WARNING
ACROSS THE ENTIRE CWFA. IT WILL BE CLOSE PER THE DEFINITION OF 7"
IN 12HRS OR 9" IN 24HRS BUT WITH A HIGH IMPACT WIDESPREAD EVENT
THE WARNING WAS EXPANDED. AS WARM ADVECTION OCCURS IN THE THERMAL
PROFILES...SOME OF THE PRECIP ACROSS DUTCHESS AND LITCHFIELD
COUNTIES WILL MIX WITH SLEET AND FREEZING RAIN LATE TONIGHT. ICE
ACCUMULATIONS UP TO TWO TENTHS OF AN INCH ARE POSSIBLE BEFORE THE
WARM AIR AT THE SURFACE ARRIVES TO RESULT IN A CHANGEOVER TO
MAINLY RAIN/RAIN SHOWERS LATER SUNDAY MORNING. SO TEMPERATURES
WILL BE STEADY TO SLOWLY RISING OVERNIGHT AS WE WILL SHOW A NON-
DIURNAL TEMPERATURE TREND OVERNIGHT.
THE OTHER COMPLICATED FACTOR TO THIS WILL BE TRANSITIONING
SNOW TO LIQUID RATIOS AS WE SHOULD INITIALLY BE RATHER HIGH WITH
15:1 RATIO THEN GRADUALLY DROPPING TOWARD CLIMATOLOGY OF 12:1 FOR
MOST OF THE REGION AND EVENTUALLY TOWARD 10:1 TOWARD SUNRISE
SUNDAY. THE CROSS SECTIONS NOW REVEAL WE WILL INDEED SEE THE BEST
LIFT OCCUR IN THE BEST DENDRITIC SNOW GROWTH REGION WHICH ALONG
WITH FGEN BANDS TO ENHANCE SNOWFALL RATES. IN FACT...D-THETA/DZ
SUGGESTS THE SMALL POTENTIAL FOR CONVECTIVE ELEMENTS BETWEEN 06Z-
12Z SUNDAY AND AS THE SECONDARY LOW DEVELOPS OFF THE NJ
COAST...THE DUCT FUNCTION POINTS TOWARD THE POTENTIAL FOR A
GRAVITY WAVE/S/.
PRECIP SHADOW IS INDEED STILL PLAUSIBLE TOO AS LOW-MID LEVEL EAST-
SOUTHEAST WINDS INCREASE SUGGESTING PRECIP SHADOW DOWNWIND OF THE
BERKS-TACONICS AND THE GREENS INTO PORTIONS OF WASHINGTON COUNTY.
THIS STORM DEEPENS SUNDAY AS IT TRACKS THROUGH THE SOUTHERN
PORTIONS OF THE GULF OF MAINE WITH DEFORMATION SNOW AXIS ACROSS
PORTIONS OF THE DACKS. WIND GUSTS WILL LIKELY INCREASE TOO WHICH
WILL RESULT IN SOME BLOWING AND DRIFTING OF THE SNOW.
FURTHERMORE...WIND CHILLS WILL LIKELY DIP WELL BELOW ZERO ACROSS
THE DACKS AS WE MAY NEED HEADLINES FOR THIS IN FUTURE FORECASTS.
SNOW WILL TAPER OFF THROUGH THE DAYLIGHT HOURS SUNDAY WITH SOME
LAKE RESPONSE SUNDAY NIGHT INTO PORTIONS OF THE DACKS...WESTERN
MOHAWK VALLEY AND CATSKILLS.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
BEHIND THE DEPARTING WINTER STORM...HIGH PRESSURE WILL MOVE OVER
THE REGION FOR MONDAY. WITH A COLD NW FLOW IN PLACE...MAX TEMPS
WILL BE BELOW NORMAL...WITH TEENS TO MID 20S ACROSS THE REGION.
VERY COLD TEMP WILL CONTINUE INTO MONDAY NIGHT WITH SINGLE DIGITS
OVER MUCH OF THE AREA. SOME BELOW ZERO READINGS WILL OCCUR ACROSS
THE ADIRONDACKS AND GREEN MOUNTAINS.
CLOUDS WILL BEGIN TO INCREASE LATE MONDAY NIGHT...WITH A SLIGHT CHC
FOR SOME SNOW SHOWERS...AS A CLIPPER SYSTEM BEGINS TO APPROACH FROM
THE GREAT LAKES. THIS WEAK SYSTEM WILL BE QUITE MOISTURE STARVED.
STILL...THERE IS A CHANCE FOR SOME LIGHT SNOW ACROSS THE REGION FOR
TUESDAY INTO TUESDAY NIGHT AS THIS SYSTEM TRACKS ACROSS THE AREA.
ANY QPF LOOKS RATHER LIGHT...AND SNOWFALL WILL ONLY BE AN INCH OR
TWO FOR MOST PLACES. MAX TEMPS WILL CONTINUE TO BE CHILLY ON TUESDAY
WITH 20S OVER MUCH OF THE AREA...AND TEENS TO LOW 20S FOR TUESDAY
NIGHT.
SOME LAKE EFFECT SNOW WILL OCCUR ACROSS THE WESTERN ADIRONDACKS AND
WESTERN MOHAWK VALLEY BEHIND THIS CLIPPER SYSTEM FOR WED INTO WED
NIGHT. OTHERWISE...IT LOOKS DRY OVER MUCH OF THE AREA. TEMPS ON WED
WILL BE A LITTLE WARMER THAN RECENT DAYS...WITH MID 20S TO MID 30S.
HOWEVER...A REINFORCING SHOT OF COLD AIR LOOKS TO ARRIVE ON WED
NIGHT...WITH TEENS FOR THE AREA...AND TEMPS BACK INTO THE 20S FOR
THURSDAY.
THIS COLD SHOT LOOKS TO BE SHORT LIVED...AS HIGH PRESSURE QUICKLY
PASSES OVER THE AREA...AND THE PATTERN BEGINS TO SHIFT SOMEWHAT.
WHILE IT WILL BE DRY FOR THURSDAY...THE OVERALL FLOW STARTS TO
BECOME MORE OUT OF THE SW BOTH AT THE LOW LEVELS AND ALOFT. THIS
WILL TRANSPORT MUCH WARMER AND MORE MOIST AIR INTO THE REGION FOR
THE LATE WEEK PERIOD. MAX TEMPS LOOK TO REACH INTO THE 40S FOR
VALLEY AREAS BY FRIDAY. ALTHOUGH IT/S STILL RATHER FAR OUT IN
TIME...AN APPROACHING SLOW MOVING FRONTAL BOUNDARY LOOKS TO BRING A
PERIOD OF PLAIN RAIN TO THE REGION FOR LATE IN THE WEEK AND INTO THE
WEEKEND ACROSS THE ENTIRE REGION...EVEN THE HIGHER TERRAIN
AREAS...WITH A RETURN TO ABOVE NORMAL TEMPS EXPECTED INTO THE
WEEKEND.
&&
.AVIATION /13Z SATURDAY THROUGH WEDNESDAY/...
A STORM SYSTEM WILL MOVE TOWARDS THE OHIO VALLEY TODAY AND REFORM
OFF THE JERSEY SHORE BY THIS EVENING. AS THIS STORM SYSTEM EVOLVES
AND MOVES TOWARDS THE AREA...LIGHT SNOW WILL CONTINUE TO SLOWLY
SPREAD NORTHWARD. SNOW HAS ALREADY BEGUN AT KPOU...AND SHOULD BEGIN
AT KPSF SOON...KALB BY ABOUT MID MORNING...AND KGFL BY LATE MORNING
OR SO. INITIALLY...THE DRY AIRMASS IN PLACE WILL ONLY ALLOW FOR
LIGHT SNOW AND MVFR CONDITIONS. AFTER ABOUT AN HOUR OR TWO...IFR
SNOW LOOKS FALL WITHIN PERIODS OF LIGHT SNOW. ALTHOUGH AT FIRST THE
SNOW MAY NOT BE STEADY AND FLYING CONDITIONS FLUCTUATE BETWEEN
IFR/MVFR...ALL SITES SHOULD BE SEEING PREDOMINATELY IFR SNOW BY
LATER THIS AFTN AS THE SNOW BEGINS TO BECOME MORE WIDESPREAD. WINDS
TODAY WILL BE N-NE AT AROUND 5 KTS.
AS THE STORM STRENGTHENS RAPIDLY OFF THE COAST...THE SNOW WILL PICK
UP IN INTENSITY BY LATE THIS EVENING AND INTO THE OVERNIGHT HOURS.
AT THIS POINT...LIFR CONDITIONS ARE POSSIBLE AS WELL...WHEN THE SNOW
WILL BE FALLING ITS HARDEST AND VV WILL BE QUITE LIMITED. VSBYS WILL
BE LESS THAN ONE MILE...AND PERHAPS AS LOW AS 1/4SM TO 1/2SM. THE
PRECIP WILL MIX WITH AND CHANGE TO SLEET/FREEZING RAIN AT KPOU AFTER
MIDNIGHT...BUT THE REMAINING SITES WILL STAY ALL SNOW. THE SNOW MAY
START TO DECREASE IN INTENSITY LATE TONIGHT FROM SOUTH TO NORTH AS
THE STORM BEGINS TO MOVE UP TOWARDS NEW ENGLAND...ALTHOUGH FLYING
CONDITIONS WILL REMAIN IFR THROUGH 12Z.
OUTLOOK...
SUN: HIGH OPERATIONAL IMPACT. SN.
SUN NIGHT-MON: LOW OPERATIONAL IMPACT. BREEZY.
MON NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUE-TUE NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SN.
WED: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
NO HYDRO RELATED CONCERNS ARE EXPECTED THE NEXT 5 DAYS.
QPF FROM THIS UPCOMING EVENT WILL RANGE FROM ONE HALF INCH TO ONE
AND ONE QUARTER OF AN INCH WITH THOSE HIGHER VALUES ACROSS THE
TERRAIN INTO THE CATSKILLS...SOUTHERN GREENS AND PORTIONS OF THE
DACKS. MOST OF THIS WILL FALL IN THE FORM OF SNOW WITH THE
EXCEPTION ACROSS DUTCHESS AND LITCHFIELD COUNTIES WHERE A WINTRY
MIXTURE AND PERHAPS A PERIOD OF RAIN MAY RESULT LATE SATURDAY
NIGHT INTO SUNDAY MORNING. ANY LIQUID PRECIP SHOULD RESULT WITHIN
BANK RISES.
THEREAFTER...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE WILL
CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND
PARTICULARLY LAKES THROUGH EARLY NEXT WEEK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR CTZ001-013.
NY...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR NYZ032-033-
038>043-047>054-058>061-063>066-082>084.
MA...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR MAZ001-025.
VT...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR VTZ013>015.
&&
$$
SYNOPSIS...BGM
NEAR TERM...IAA/BGM
SHORT TERM...BGM
LONG TERM...FRUGIS
AVIATION...FRUGIS
HYDROLOGY...BGM
AREA FORECAST DISCUSSION
NWS ALBANY NY
620 AM EST SAT DEC 14 2013
.SYNOPSIS...
ARCTIC HIGH PRESSURE SITUATED ACROSS THE SAINT LAWRENCE VALLEY
HAS USHERED IN A VERY COLD AND DRY AIR MASS INTO THE REGION.
MEANWHILE A COMPLEX WINTER STORM IS TAKING SHAPE ACROSS THE
CENTER OF THE NATION AND WILL TRACK TOWARD NEW ENGLAND TONIGHT.
THIS WILL SPREAD AN ACCUMULATING SNOW ACROSS MOST OF THE REGION.
THIS STORM WILL DEPART BY SUNDAY AFTERNOON WITH SLOW IMPROVEMENTS
TO OUR WEATHER EXPECTED.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 600 AM EST...LIGHT SNOW WAS ALREADY DEVELOPING ACROSS THE
CATSKILLS...SCHOHARIE VALLEY...IN THE IMMEDIATE CAPITAL
REGION...BERKSHIRES...MID HUDSON VALLEY. RADAR REPRESENTATION IS
LESS THAN IMPRESSIVE AS MOST OF THIS SNOW IS FALLING VERY LIGHTLY.
LATEST 06Z GUIDANCE AND HOURLY RUC/HRRR CONTINUE ALONG THE SAME
FORECAST THOUGHTS WITH WAA ISENTROPIC LIFT EVOLVING ALONG A
TIGHTENING BAROCLINIC ZONE ALONG AND JUST NORTH OF THE NY STATE
LINE. QPF/S CONTINUE TO SHOW A SLIGHT INCREASE FROM PREVIOUS RUNS
SO WE MADE SLIGHT ADJUSTMENTS TO THE SNOWFALL FORECAST TODAY.
PREV DISC...
H2O VAPOR LOOP REVEALS OUR MAIN INGREDIENT FOR OUR
WINTER STORM WAS TRACKING ACROSS NORTHERN ARKANSAS AND SOUTHERN
MISSOURI AND TRACKING NORTHEAST TOWARD THE OHIO VALLEY. A
STRENGTHENING UPPER JET IS UNDERWAY ACROSS THE SOUTHERN CONUS PER
SATELLITE WIND ESTIMATES AND HOURLY RUC ANALYSIS WITH ANOTHER
UPPER JET SEGMENT ACROSS THE UPPER GREAT LAKES REGION. THIS
NORTHERN PORTION OF THE JET IS EXPECTED TO REMAIN CYCLONIC IN
NATURE WHICH SUGGESTS THIS UPPER LOW MAY TRACK A LITTLE FURTHER
WEST AND HANGING ONTO THE INITIAL SURFACE LOW LONGER BEFORE THE
TRANSFER OCCURS OFF THE MID ATLANTIC COAST. BROAD ISENTROPIC LIFT
IN ADVANCE OF THESE FEATURES WAS UNDERWAY ACROSS THE NY/PA BORDER
AS BAROCLINICITY WAS INCREASING JUST NORTH OF THE ARCTIC BOUNDARY.
PER EXPERIMENTAL REFLECTIVITY FORECASTS FROM A VARIETY OF
MESOSCALE MODELS...ALONG WITH THE DRY AIR IN PLACE...IT MAY TAKE
MOST OF THE MORNING TO SATURATE THE LOWER LEVELS FOR SNOW TO REACH
THE GROUND /VIRGA/ NORTH OF I90 AS LOW LEVEL AGEOSTROPIC FLOW
REMAINS IN PLACE /MAGNITUDE IS NOT THAT STRONG BUT IS VERY
PERSISTENT/. THEREFORE...WE WILL SLOW DOWN THE ONSET OF PRECIP IN
THE GRIDS FROM SOUTH TO NORTH TODAY. AS FOR HIGH
TEMPERATURES...BLENDED APPROACH OF THE MOS GUIDANCE WAS UTILIZED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
...WINTER STORM WARNING IN EFFECT FOR THE ENTIRE REGION...
PREVIOUS DISCUSSIONS HAVE DONE AN EXCELLENT JOB WITH THE
METEOROLOGICAL PARAMETERS SETTING UP FOR THIS FIRST WIDESPREAD
SIGNIFICANT WINTER EVENT FOR THE REGION. 00Z GUIDANCE ALONG WITH THE
RECENT ARRIVAL OF THE 06Z NAM/GFS CONTINUE TO INCREASE QPF AMOUNTS
ALONG WITH ENHANCED FGEN BANDS SEEN IN THE H850-H700 LAYER PER
PREVIOUS CSTAR RESEARCH. THESE BANDS ARE PROGGED TO BE A LITTLE
FURTHER NORTH AND PER COORDINATION FROM WPC AND SURROUNDING
WFOS...WE WILL UPGRADE THE ADVISORY AREA AND EXTEND THE WARNING
ACROSS THE ENTIRE CWFA. IT WILL BE CLOSE PER THE DEFINITION OF 7"
IN 12HRS OR 9" IN 24HRS BUT WITH A HIGH IMPACT WIDESPREAD EVENT
THE WARNING WAS EXPANDED. AS WARM ADVECTION OCCURS IN THE THERMAL
PROFILES...SOME OF THE PRECIP ACROSS DUTCHESS AND LITCHFIELD
COUNTIES WILL MIX WITH SLEET AND FREEZING RAIN LATE TONIGHT. ICE
ACCUMULATIONS UP TO TWO TENTHS OF AN INCH ARE POSSIBLE BEFORE THE
WARM AIR AT THE SURFACE ARRIVES TO RESULT IN A CHANGEOVER TO
MAINLY RAIN/RAIN SHOWERS LATER SUNDAY MORNING. SO TEMPERATURES
WILL BE STEADY TO SLOWLY RISING OVERNIGHT AS WE WILL SHOW A NON-
DIURNAL TEMPERATURE TREND OVERNIGHT.
THE OTHER COMPLICATED FACTOR TO THIS WILL BE TRANSITIONING
SNOW TO LIQUID RATIOS AS WE SHOULD INITIALLY BE RATHER HIGH WITH
15:1 RATIO THEN GRADUALLY DROPPING TOWARD CLIMATOLOGY OF 12:1 FOR
MOST OF THE REGION AND EVENTUALLY TOWARD 10:1 TOWARD SUNRISE
SUNDAY. THE CROSS SECTIONS NOW REVEAL WE WILL INDEED SEE THE BEST
LIFT OCCUR IN THE BEST DENDRITIC SNOW GROWTH REGION WHICH ALONG
WITH FGEN BANDS TO ENHANCE SNOWFALL RATES. IN FACT...D-THETA/DZ
SUGGESTS THE SMALL POTENTIAL FOR CONVECTIVE ELEMENTS BETWEEN 06Z-
12Z SUNDAY AND AS THE SECONDARY LOW DEVELOPS OFF THE NJ
COAST...THE DUCT FUNCTION POINTS TOWARD THE POTENTIAL FOR A
GRAVITY WAVE/S/.
PRECIP SHADOW IS INDEED STILL PLAUSIBLE TOO AS LOW-MID LEVEL EAST-
SOUTHEAST WINDS INCREASE SUGGESTING PRECIP SHADOW DOWNWIND OF THE
BERKS-TACONICS AND THE GREENS INTO PORTIONS OF WASHINGTON COUNTY.
THIS STORM DEEPENS SUNDAY AS IT TRACKS THROUGH THE SOUTHERN
PORTIONS OF THE GULF OF MAINE WITH DEFORMATION SNOW AXIS ACROSS
PORTIONS OF THE DACKS. WIND GUSTS WILL LIKELY INCREASE TOO WHICH
WILL RESULT IN SOME BLOWING AND DRIFTING OF THE SNOW.
FURTHERMORE...WIND CHILLS WILL LIKELY DIP WELL BELOW ZERO ACROSS
THE DACKS AS WE MAY NEED HEADLINES FOR THIS IN FUTURE FORECASTS.
SNOW WILL TAPER OFF THROUGH THE DAYLIGHT HOURS SUNDAY WITH SOME
LAKE RESPONSE SUNDAY NIGHT INTO PORTIONS OF THE DACKS...WESTERN
MOHAWK VALLEY AND CATSKILLS.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
BEHIND THE DEPARTING WINTER STORM...HIGH PRESSURE WILL MOVE OVER
THE REGION FOR MONDAY. WITH A COLD NW FLOW IN PLACE...MAX TEMPS
WILL BE BELOW NORMAL...WITH TEENS TO MID 20S ACROSS THE REGION.
VERY COLD TEMP WILL CONTINUE INTO MONDAY NIGHT WITH SINGLE DIGITS
OVER MUCH OF THE AREA. SOME BELOW ZERO READINGS WILL OCCUR ACROSS
THE ADIRONDACKS AND GREEN MOUNTAINS.
CLOUDS WILL BEGIN TO INCREASE LATE MONDAY NIGHT...WITH A SLIGHT CHC
FOR SOME SNOW SHOWERS...AS A CLIPPER SYSTEM BEGINS TO APPROACH FROM
THE GREAT LAKES. THIS WEAK SYSTEM WILL BE QUITE MOISTURE STARVED.
STILL...THERE IS A CHANCE FOR SOME LIGHT SNOW ACROSS THE REGION FOR
TUESDAY INTO TUESDAY NIGHT AS THIS SYSTEM TRACKS ACROSS THE AREA.
ANY QPF LOOKS RATHER LIGHT...AND SNOWFALL WILL ONLY BE AN INCH OR
TWO FOR MOST PLACES. MAX TEMPS WILL CONTINUE TO BE CHILLY ON TUESDAY
WITH 20S OVER MUCH OF THE AREA...AND TEENS TO LOW 20S FOR TUESDAY
NIGHT.
SOME LAKE EFFECT SNOW WILL OCCUR ACROSS THE WESTERN ADIRONDACKS AND
WESTERN MOHAWK VALLEY BEHIND THIS CLIPPER SYSTEM FOR WED INTO WED
NIGHT. OTHERWISE...IT LOOKS DRY OVER MUCH OF THE AREA. TEMPS ON WED
WILL BE A LITTLE WARMER THAN RECENT DAYS...WITH MID 20S TO MID 30S.
HOWEVER...A REINFORCING SHOT OF COLD AIR LOOKS TO ARRIVE ON WED
NIGHT...WITH TEENS FOR THE AREA...AND TEMPS BACK INTO THE 20S FOR
THURSDAY.
THIS COLD SHOT LOOKS TO BE SHORT LIVED...AS HIGH PRESSURE QUICKLY
PASSES OVER THE AREA...AND THE PATTERN BEGINS TO SHIFT SOMEWHAT.
WHILE IT WILL BE DRY FOR THURSDAY...THE OVERALL FLOW STARTS TO
BECOME MORE OUT OF THE SW BOTH AT THE LOW LEVELS AND ALOFT. THIS
WILL TRANSPORT MUCH WARMER AND MORE MOIST AIR INTO THE REGION FOR
THE LATE WEEK PERIOD. MAX TEMPS LOOK TO REACH INTO THE 40S FOR
VALLEY AREAS BY FRIDAY. ALTHOUGH IT/S STILL RATHER FAR OUT IN
TIME...AN APPROACHING SLOW MOVING FRONTAL BOUNDARY LOOKS TO BRING A
PERIOD OF PLAIN RAIN TO THE REGION FOR LATE IN THE WEEK AND INTO THE
WEEKEND ACROSS THE ENTIRE REGION...EVEN THE HIGHER TERRAIN
AREAS...WITH A RETURN TO ABOVE NORMAL TEMPS EXPECTED INTO THE
WEEKEND.
&&
.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
A STORM SYSTEM WILL MOVE TOWARDS THE OHIO VALLEY TODAY AND REFORM
OFF THE JERSEY SHORE BY THIS EVENING. AS THIS STORM SYSTEM EVOLVES
AND MOVES TOWARDS THE AREA...LIGHT SNOW WILL CONTINUE TO SLOWLY
SPREAD NORTHWARD. SNOW HAS ALREADY BEGUN AT KPOU...AND SHOULD BEGIN
AT KPSF SOON...KALB BY ABOUT MID MORNING...AND KGFL BY LATE MORNING
OR SO. INITIALLY...THE DRY AIRMASS IN PLACE WILL ONLY ALLOW FOR
LIGHT SNOW AND MVFR CONDITIONS. AFTER ABOUT AN HOUR OR TWO...IFR
SNOW LOOKS FALL WITHIN PERIODS OF LIGHT SNOW. ALTHOUGH AT FIRST THE
SNOW MAY NOT BE STEADY AND FLYING CONDITIONS FLUCTUATE BETWEEN
IFR/MVFR...ALL SITES SHOULD BE SEEING PREDOMINATELY IFR SNOW BY
LATER THIS AFTN AS THE SNOW BEGINS TO BECOME MORE WIDESPREAD. WINDS
TODAY WILL BE N-NE AT AROUND 5 KTS.
AS THE STORM STRENGTHENS RAPIDLY OFF THE COAST...THE SNOW WILL PICK
UP IN INTENSITY BY LATE THIS EVENING AND INTO THE OVERNIGHT HOURS.
AT THIS POINT...LIFR CONDITIONS ARE POSSIBLE AS WELL...WHEN THE SNOW
WILL BE FALLING ITS HARDEST AND VV WILL BE QUITE LIMITED. VSBYS WILL
BE LESS THAN ONE MILE...AND PERHAPS AS LOW AS 1/4SM TO 1/2SM. THE
PRECIP WILL MIX WITH AND CHANGE TO SLEET/FREEZING RAIN AT KPOU AFTER
MIDNIGHT...BUT THE REMAINING SITES WILL STAY ALL SNOW. THE SNOW MAY
START TO DECREASE IN INTENSITY LATE TONIGHT FROM SOUTH TO NORTH AS
THE STORM BEGINS TO MOVE UP TOWARDS NEW ENGLAND...ALTHOUGH FLYING
CONDITIONS WILL REMAIN IFR THROUGH 12Z.
OUTLOOK...
SUNDAY: HIGH OPERATIONAL IMPACT. SN.
SUNDAY NIGHT-MONDAY: LOW OPERATIONAL IMPACT.BREEZY NO SIG WX.
MONDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUESDAY-TUESDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SN.
WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
NO HYDRO RELATED CONCERNS ARE EXPECTED THE NEXT 5 DAYS.
QPF FROM THIS UPCOMING EVENT WILL RANGE FROM ONE HALF INCH TO ONE
AND ONE QUARTER OF AN INCH WITH THOSE HIGHER VALUES ACROSS THE
TERRAIN INTO THE CATSKILLS...SOUTHERN GREENS AND PORTIONS OF THE
DACKS. MOST OF THIS WILL FALL IN THE FORM OF SNOW WITH THE
EXCEPTION ACROSS DUTCHESS AND LITCHFIELD COUNTIES WHERE A WINTRY
MIXTURE AND PERHAPS A PERIOD OF RAIN MAY RESULT LATE SATURDAY
NIGHT INTO SUNDAY MORNING. ANY LIQUID PRECIP SHOULD RESULT WITHIN
BANK RISES.
THEREAFTER...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE WILL
CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND
PARTICULARLY LAKES THROUGH EARLY NEXT WEEK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR CTZ001-013.
NY...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR NYZ032-033-
038>043-047>054-058>061-063>066-082>084.
MA...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR MAZ001-025.
VT...WINTER STORM WARNING UNTIL 1 PM EST SUNDAY FOR VTZ013>015.
&&
$$
SYNOPSIS...BGM
NEAR TERM...BGM
SHORT TERM...BGM
LONG TERM...FRUGIS
AVIATION...FRUGIS
HYDROLOGY...BGM
FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT
WWW.WEATHER.GOV/ALBANY
AREA FORECAST DISCUSSION
NWS ALBANY NY
348 AM EST SAT DEC 14 2013
.SYNOPSIS...
ARCTIC HIGH PRESSURE SITUATED ACROSS THE SAINT LAWRENCE VALLEY
HAS USHERED IN A VERY COLD AND DRY AIR MASS INTO THE REGION.
MEANWHILE A COMPLEX WINTER STORM IS TAKING SHAPE ACROSS THE
CENTER OF THE NATION AND WILL TRACK TOWARD NEW ENGLAND TONIGHT.
THIS WILL SPREAD AN ACCUMULATING SNOW ACROSS MOST OF THE REGION.
THIS STORM WILL DEPART BY SUNDAY AFTERNOON WITH SLOW IMPROVEMENTS
TO OUR WEATHER EXPECTED.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
H2O VAPOR LOOP REVEALS OUR MAIN INGREDIENT FOR OUR WINTER STORM
WAS TRACKING ACROSS NORTHERN ARKANSAS AND SOUTHERN MISSOURI AND
TRACKING NORTHEAST TOWARD THE OHIO VALLEY. A STRENGTHENING UPPER
JET IS UNDERWAY ACROSS THE SOUTHERN CONUS PER SATELLITE WIND
ESTIMATES AND HOURLY RUC ANALYSIS WITH ANOTHER UPPER JET SEGMENT
ACROSS THE UPPER GREAT LAKES REGION. THIS NORTHERN PORTION OF THE
JET IS EXPECTED TO REMAIN CYCLONIC IN NATURE WHICH SUGGESTS THIS
UPPER LOW MAY TRACK A LITTLE FURTHER WEST AND HANGING ONTO THE
INITIAL SURFACE LOW LONGER BEFORE THE TRANSFER OCCURS OFF THE MID
ATLANTIC COAST. BROAD ISENTROPIC LIFT IN ADVANCE OF THESE FEATURES
WAS UNDERWAY ACROSS THE NY/PA BORDER AS BAROCLINICITY WAS
INCREASING JUST NORTH OF THE ARCTIC BOUNDARY. PER EXPERIMENTAL
REFLECTIVITY FORECASTS FROM A VARIETY OF MESOSCALE MODELS...ALONG
WITH THE DRY AIR IN PLACE...IT MAY TAKE MOST OF THE MORNING TO
SATURATE THE LOWER LEVELS FOR SNOW TO REACH THE GROUND /VIRGA/
SOUTH OF I90 AS LOW LEVEL AGEOSTROPIC FLOW REMAINS IN PLACE
/MAGNITUDE IS NOT THAT STRONG BUT IS VERY PERSISTENT/.
THEREFORE...WE WILL SLOW DOWN THE ONSET OF PRECIP IN THE GRIDS
FROM SOUTH TO NORTH TODAY. AD FOR HIGH TEMPERATURES...BLENDED
APPROACH OF THE MOS GUIDANCE WAS UTILIZED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
...WINTER STORM WARNING IN EFFECT FOR THE ENTIRE REGION...
PREVIOUS DISCUSSIONS HAVE DONE AN EXCELLENT JOB WITH THE
METEOROLOGICAL PARAMETERS SETTING UP FOR THIS FIRST WIDESPREAD
SIGNIFICANT WINTER EVENT FOR THE REGION. 00Z GUIDANCE ALONG WITH THE
RECENT ARRIVAL OF THE 06Z NAM CONTINUE TO INCREASE QPF AMOUNTS
ALONG WITH ENHANCED FGEN BANDS SEEN IN THE H850-H700 LAYER PER
PREVIOUS CSTAR RESEARCH. THESE BANDS ARE PROGGED TO BE A LITTLE
FURTHER NORTH AND PER COORDINATION FROM WPC AND SURROUNDING
WFOS...WE WILL UPGRADE THE ADVISORY AREA AND EXTEND THE WARNING
ACROSS THE ENTIRE CWFA. IT WILL BE CLOSE PER THE DEFINITION OF 7"
IN 12HRS OR 9" IN 24HRS BUT WITH A HIGH IMPACT WIDESPREAD EVENT
THE WARNING WAS EXPANDED. AS WARM ADVECTION OCCURS IN THE THERMAL
PROFILES...SOME OF THE PRECIP ACROSS DUTCHESS AND LITCHFIELD
COUNTIES WILL MIX WITH SLEET AND FREEZING RAIN LATE TONIGHT. ICE
ACCUMULATIONS UP TO TWO TENTHS OF AN INCH ARE POSSIBLE BEFORE THE
WARM AIR AT THE SURFACE ARRIVES TO RESULT IN A CHANGEOVER TO
MAINLY RAIN/RAIN SHOWERS LATER SUNDAY MORNING. SO TEMPERATURES
WILL BE STEADY TO SLOWLY RISING OVERNIGHT AS WE WILL SHOW A NON-
DIURNAL TEMPERATURE TREND OVERNIGHT.
THE OTHER COMPLICATED FACTOR TO THIS WILL BE TRANSITIONING
SNOW TO LIQUID RATIOS AS WE SHOULD INITIALLY BE RATHER HIGH WITH
15:1 RATIO THEN GRADUALLY DROPPING TOWARD CLIMATOLOGY OF 12:1 FOR
MOST OF THE REGION AND EVENTUALLY TOWARD 10:1 TOWARD SUNRISE
SUNDAY. THE CROSS SECTIONS NOW REVEAL WE WILL INDEED SEE THE BEST
LIFT OCCUR IN THE BEST DENDRITIC SNOW GROWTH REGION WHICH ALONG
WITH FGEN BANDS TO ENHANCE SNOWFALL RATES. IN FACT...D-THETA/DZ
SUGGESTS THE SMALL POTENTIAL FOR CONVECTIVE ELEMENTS BETWEEN 06Z-
12Z SUNDAY AND AS THE SECONDARY LOW DEVELOPS OFF THE NJ
COAST...THE DUCT FUNCTION POINTS TOWARD THE POTENTIAL FOR A
GRAVITY WAVE/S/.
PRECIP SHADOW IS INDEED STILL PLAUSIBLE TOO AS LOW-MID LEVEL EAST-
SOUTHEAST WINDS INCREASE SUGGESTING PRECIP SHADOW DOWNWIND OF THE
BERKS-TACONICS AND THE GREENS INTO PORTIONS OF WASHINGTON COUNTY.
THIS STORM DEEPENS SUNDAY AS IT TRACKS THROUGH THE SOUTHERN
PORTIONS OF THE GULF OF MAINE WITH DEFORMATION SNOW AXIS ACROSS
PORTIONS OF THE DACKS. WIND GUSTS WILL LIKELY INCREASE TOO WHICH
WILL RESULT IN SOME BLOWING AND DRIFTING OF THE SNOW.
FURTHERMORE...WIND CHILLS WILL LIKELY DIP WELL BELOW ZERO ACROSS
THE DACKS AS WE MAY NEED HEADLINES FOR THIS IN FUTURE FORECASTS.
SNOW WILL TAPER OFF THROUGH THE DAYLIGHT HOURS SUNDAY WITH SOME
LAKE RESPONSE SUNDAY NIGHT INTO PORTIONS OF THE DACKS...WESTERN
MOHAWK VALLEY AND CATSKILLS.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
BEHIND THE DEPARTING WINTER STORM...HIGH PRESSURE WILL MOVE OVER
THE REGION FOR MONDAY. WITH A COLD NW FLOW IN PLACE...MAX TEMPS
WILL BE BELOW NORMAL...WITH TEENS TO MID 20S ACROSS THE REGION.
VERY COLD TEMP WILL CONTINUE INTO MONDAY NIGHT WITH SINGLE DIGITS
OVER MUCH OF THE AREA. SOME BELOW ZERO READINGS WILL OCCUR ACROSS
THE ADIRONDACKS AND GREEN MOUNTAINS.
CLOUDS WILL BEGIN TO INCREASE LATE MONDAY NIGHT...WITH A SLIGHT CHC
FOR SOME SNOW SHOWERS...AS A CLIPPER SYSTEM BEGINS TO APPROACH FROM
THE GREAT LAKES. THIS WEAK SYSTEM WILL BE QUITE MOISTURE STARVED.
STILL...THERE IS A CHANCE FOR SOME LIGHT SNOW ACROSS THE REGION FOR
TUESDAY INTO TUESDAY NIGHT AS THIS SYSTEM TRACKS ACROSS THE AREA.
ANY QPF LOOKS RATHER LIGHT...AND SNOWFALL WILL ONLY BE AN INCH OR
TWO FOR MOST PLACES. MAX TEMPS WILL CONTINUE TO BE CHILLY ON TUESDAY
WITH 20S OVER MUCH OF THE AREA...AND TEENS TO LOW 20S FOR TUESDAY
NIGHT.
SOME LAKE EFFECT SNOW WILL OCCUR ACROSS THE WESTERN ADIRONDACKS AND
WESTERN MOHAWK VALLEY BEHIND THIS CLIPPER SYSTEM FOR WED INTO WED
NIGHT. OTHERWISE...IT LOOKS DRY OVER MUCH OF THE AREA. TEMPS ON WED
WILL BE A LITTLE WARMER THAN RECENT DAYS...WITH MID 20S TO MID 30S.
HOWEVER...A REINFORCING SHOT OF COLD AIR LOOKS TO ARRIVE ON WED
NIGHT...WITH TEENS FOR THE AREA...AND TEMPS BACK INTO THE 20S FOR
THURSDAY.
THIS COLD SHOT LOOKS TO BE SHORT LIVED...AS HIGH PRESSURE QUICKLY
PASSES OVER THE AREA...AND THE PATTERN BEGINS TO SHIFT SOMEWHAT.
WHILE IT WILL BE DRY FOR THURSDAY...THE OVERALL FLOW STARTS TO
BECOME MORE OUT OF THE SW BOTH AT THE LOW LEVELS AND ALOFT. THIS
WILL TRANSPORT MUCH WARMER AND MORE MOIST AIR INTO THE REGION FOR
THE LATE WEEK PERIOD. MAX TEMPS LOOK TO REACH INTO THE 40S FOR
VALLEY AREAS BY FRIDAY. ALTHOUGH IT/S STILL RATHER FAR OUT IN
TIME...AN APPROACHING SLOW MOVING FRONTAL BOUNDARY LOOKS TO BRING A
PERIOD OF PLAIN RAIN TO THE REGION FOR LATE IN THE WEEK AND INTO THE
WEEKEND ACROSS THE ENTIRE REGION...EVEN THE HIGHER TERRAIN
AREAS...WITH A RETURN TO ABOVE NORMAL TEMPS EXPECTED INTO THE
WEEKEND.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
CLOUDS WILL BE INCREASING THROUGH THE REMAINDER OF THE NIGHT...AS
A STORM SYSTEM ORGANIZES OVER THE SOUTHEAST AND MOISTURE CONTINUES
TO SPREAD NORTHEAST. FLYING CONDITIONS WILL GENERALLY BE VFR FOR
THE VALLEY TERMINALS WITH BKN-OVC CIGS OF 3500-6000 FT THROUGH THE
REMAINDER OF THE OVERNIGHT HOURS. HOWEVER...SOME BKN CIGS AROUND
1500-2000 FT ARE POSSIBLE FOR KPSF...ALLOWING FOR A PERIOD OF MVFR
CONDITIONS OVER THE BERKSHIRES. IT SHOULD REMAIN DRY THROUGH THE
REMAINDER OF THE OVERNIGHT AS WELL...WITH A LIGHT N-NE WIND AROUND
5 KTS.
AS THE STORM SYSTEM STRENGTHENS AND MOVES ACROSS THE
SOUTHEAST...LIGHT SNOW WILL DEVELOP ACROSS SOUTHERN AREAS DURING THE
MORNING HOURS AND SLOWLY SPREAD NORTHWARD. SNOW LOOKS TO BEGIN AT
KPOU AS EARLY AS 15Z...BUT WILL TAKE UNTIL 18Z TO GET GOING AT KALB.
INITIALLY...THE DRY AIRMASS IN PLACE WILL ONLY ALLOW FOR LIGHT SNOW
AND MVFR CONDITIONS. AFTER A FEW HOURS...ALL TERMINALS LOOK TO SEE
IFR CONDITIONS BY THE MID TO LATE AFTN HOURS WITH SNOW PICKING UP IN
INTENSITY. BY SATURDAY EVENING...LIFR CONDITIONS ARE POSSIBLE AS
WELL...WHEN THE SNOW WILL BE FALLING ITS HARDEST AND VV WILL BE
QUITE LIMITED. DURING THE DAY SATURDAY...WINDS WILL GENERALLY BE
FROM THE NE AND WILL BE STRENGTHENING TO 5-10 KTS BY SAT EVENING.
OUTLOOK...
SUNDAY: HIGH OPERATIONAL IMPACT. DEFINITE SN.
SUNDAY NIGHT-MONDAY: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUESDAY-TUESDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SN.
WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX
&&
.HYDROLOGY...
NO HYDRO RELATED CONCERNS ARE EXPECTED THE NEXT 5 DAYS.
QPF FROM THIS UPCOMING EVENT WILL RANGE FROM ONE HALF INCH TO ONE
AND ONE QUARTER OF AN INCH WITH THOSE HIGHER VALUES ACROSS THE
TERRAIN INTO THE CATSKILLS...SOUTHERN GREENS AND PORTIONS OF THE
DACKS. MOST OF THIS WILL FALL IN THE FORM OF SNOW WITH THE
EXCEPTION ACROSS DUTCHESS AND LITCHFIELD COUNTIES WHERE A WINTRY
MIXTURE AND PERHAPS A PERIOD OF RAIN MAY RESULT LATE SATURDAY
NIGHT INTO SUNDAY MORNING. ANY LIQUID PRECIP SHOULD RESULT WITHIN
BANK RISES.
THEREAFTER...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE WILL
CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND
PARTICULARLY LAKES THROUGH EARLY NEXT WEEK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING FROM 8 AM THIS MORNING TO 1 PM EST SUNDAY
FOR CTZ001-013.
NY...WINTER STORM WARNING FROM 8 AM THIS MORNING TO 1 PM EST SUNDAY
FOR NYZ032-033-038>043-047>054-058>061-063>066-082>084.
MA...WINTER STORM WARNING FROM 8 AM THIS MORNING TO 1 PM EST SUNDAY
FOR MAZ001-025.
VT...WINTER STORM WARNING FROM 8 AM THIS MORNING TO 1 PM EST SUNDAY
FOR VTZ013>015.
&&
$$
SYNOPSIS...BGM
NEAR TERM...BGM
SHORT TERM...BGM
LONG TERM...FRUGIS
AVIATION...FRUGIS
HYDROLOGY...BGM
FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT
WWW.WEATHER.GOV/ALBANY
AREA FORECAST DISCUSSION...CORRECTED
NWS TAMPA BAY RUSKIN FL
500 AM EST SAT DEC 14 2013
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A UPPER LEVEL PATTERN IN
THE PROCESS OF TRANSITIONING FROM A GENERALLY ZONAL PATTERN OVER THE
EASTERN CONUS TO A PATTERN DOMINATED BY LONGWAVE TROUGHING. THE
LEADING IMPULSES IN THIS TRANSITION IS A STRONG SHORTWAVE EJECTING
EASTWARD FROM THE MID/LOWER MS VALLEY EARLY THIS MORNING TOWARD THE
TN VALLEY AND CAROLINAS. A SECONDARY SHORTWAVE AND IMPULSE IS
FOLLOWING CLOSE BEHIND OVER THE SOUTHERN PLAINS. THIS FIRST
SHORTWAVE WILL PASS WELL TO OUR NORTH DURING THE LATER MORNING
HOURS...AND THEN THE SECOND IMPULSE WILL MAKE A CLOSER PASS ALONG
THE NORTHERN GULF COAST TONIGHT AND SUNDAY. WV IMAGERY SHOWS LOTS OF
UPPER LEVEL MOISTURE STREAMING EASTWARD AHEAD OF THESE SYSTEMS
ACROSS THE GULF OF MEXICO AND FLORIDA PENINSULA. WV IMAGERY ALSO
SHOWS STRONG SUBSIDENCE/DRYING IN THE WAKE OF THIS LEAD
IMPULSE...HOWEVER THIS SUBSIDENCE WILL BYPASS WELL TO OUR NORTH AND
WE WILL NEED TO WAIT UNTIL THE WAKE OF THE SECONDARY SHORTWAVE LATER
SUNDAY AND SUNDAY NIGHT TO FINALLY CLEAR OUR SKIES ONCE AGAIN.
AT THE SURFACE...1028MB HIGH PRESSURE IS LETTING UP ITS INFLUENCE ON
THE FL PENINSULA THIS MORNING AS IT SLIDES EASTWARD INTO THE WESTERN
ATLANTIC IN RESPONSE TO A WAVE OF LOW PRESSURE MOVING EASTWARD FROM
THE LOWER MS VALLEY. A COLD FRONT CURRENTLY EXTENDS SOUTHWARD FROM
THIS FEATURE INTO THE WESTERN GULF OF MEXICO AND WILL BE MOVING
EASTWARD ACROSS THE GULF THROUGH THE DAY. SEEING A MUCH WARMER EARLY
MORNING THAN 24 HOURS AGO WITH MOST LOCATIONS HOLDING IN THE 50S AND
60S AS EAST AND SOUTHEASTERLY LOW LEVEL FLOW CONTINUES TO ADVECT
ATLANTIC MOISTURE ACROSS THE REGION.
&&
.SHORT TERM (TODAY THROUGH MONDAY)...
TODAY...FORECAST PHILOSOPHY HAS NOT CHANGED MUCH IN TERMS OF THE
SENSIBLE WEATHER AND TIMING OF THE FRONT AND FORCING MECHANISM
THROUGH THE NEXT 24 HOURS. AS THE LEAD SHORTWAVE PIVOTS
NORTHEASTWARD THROUGH THE DAY IT WILL DRAW THE SURFACE LOW
REFLECTION TO THE NORTHEAST AS WELL. THIS SURFACE FEATURE SHOULD
REACH THE EASTERN CAROLINAS AROUND SUNDOWN THIS EVENING WITH THE
COLD FRONT TRAILING BACK THROUGH GA TO THE FL PANHANDLE AND
NORTH-CENTRAL GULF. INITIAL "BATCH" OF DEEP LAYER QG-FORCING MISSES
THE REGION TO THE NORTH...AND THE SECOND ROUND OF FORCING AHEAD OF
THE SECOND SHORTWAVE DOES NOT BEGIN TO ARRIVE OVER OUR NORTHERN
ZONES UNTIL LATE TODAY AND THIS EVENING. THIS SYNOPTIC FORCING IS
ALSO NOT COMPLIMENTED BY ANY DECENT RRQ JET DYNAMICS UNTIL THIS
EVENING AND OVERNIGHT. WITH THE LOW LEVEL FOCUS OF THE FRONT MAINLY
TO OUR WEST ALL DAY AND THE LATE ARRIVAL OF THE UPPER FORCING...
STILL EXPECT MUCH OF THE FORECAST AREA TO SEE A GENERALLY DRY DAY.
DO BRING SCATTERED SHOWERS INTO THE NORTHERN NATURE COAST ZONES
AFTER 1-2PM...BUT DO NOT RAISE RAIN CHANCES TO LIKELY UNTIL AFTER
4-5PM. RAIN CHANCES WILL QUICKLY DECREASE SOUTHWARD TO THE I-4
CORRIDOR DURING THE LATER AFTERNOON HOURS...AND JUST HAVE ISOLATED
SHOWERS IN THE FORECAST FOR THE EARLY EVENING AROUND TAMPA BAY. FAR
REMOVED FROM THE FORCING LATER TODAY...AREAS SOUTH OF TAMPA BAY SHOW
A 10% POP OR LESS. IT WILL BE VERY WARM DECEMBER DAY WITHIN THE
THERMAL RIDGE AHEAD OF THE FRONT. THIS THERMAL RIDGE COMBINED WITH
DECENT DIURNAL MIXING WILL ALLOW MANY SPOTS TO REACH THE LOWER
80S...AND EVEN SOME MIDDLE 80S FOR THE SOUTHERN ZONES. BIGGER
QUESTION ON TEMPS WILL BE NORTH OF TAMPA BAY WHERE CLOUDS WILL
THICKEN/LOWER SOONER.
TONIGHT...SECONDARY SHORTWAVE QUICKLY HELPS TO EVOLVE/DEEPEN THE
LONGWAVE TROUGH OVER THE EASTERN CONUS TONIGHT...AND THE APPROACH OF
THIS ENERGY TO THE ATLANTIC COAST IS PROGGED TO RESULT IN RAPID
CYCLOGENESIS ALONG THE MID-ATLANTIC/NEW ENGLAND BAROCLINIC ZONE.
GFS/ECMWF STILL BOTH SHOW A DECENT SWATH OF QG-FORCING OVERSPREADING
THE NORTHERN HALF OF THE PENINSULA THIS EVENING AND OVERNIGHT...BUT
WITH TIME THE MAIN ENERGY WILL BEGIN TO TRANSLATE NORTHWARD TOWARD
THE DEEPENING SYSTEM OFF THE MID-ATLANTIC COAST. THE COLD FRONT IS
NOT THE FASTEST OF MOVING FEATURES AND TAKES MOST OF THE OVERNIGHT
TO REACH LEVY COUNTY AND THE NORTHERN MARINE ZONES. WITH THE MAIN
LOW LEVEL AND UPPER FORCING OVER THE NORTHERN PENINSULA...WILL SHOW
A FAIRLY TIGHT POP GRADIENT FROM CHANCE 40-55% POPS ALONG THE I-4
CORRIDOR TO CATEGORICAL 80-90% POPS UP TOWARD CITRUS/LEVY COUNTY.
FURTHER SOUTH FROM I-4...RAIN CHANCES DIMINISH QUICKLY AND LOOKING
FOR A MAINLY DRY OVERNIGHT FOR PLACES LIKE PUNTA GORDA AND FORT
MYERS OVER INTO HIGHLANDS COUNTY. 35-40KT LOW LEVEL JET MAY RESULT
IN A FEW STRONGER WIND GUSTS FOR LEVY COUNTY ASSOCIATED WITH ANY
STORMS...BUT THE OVERALL THREAT FOR SEVERE WEATHER APPEARS MARGINAL.
DEEP SOUTHWEST FLOW AHEAD OF THE FRONT WILL KEEP IT A WARM DECEMBER
NIGHT WITH LOW TEMPS FAILING TO FALL OUT OF THE MIDDLE AND UPPER
60S.
SUNDAY/SUNDAY NIGHT...
COLD FRONT BECOMES INCREASINGLY STRETCHED AS THE LOW NEAR NEW
ENGLAND DEEPENS AND QUICKLY MOVES NORTHEAST THROUGH THE DAY. THIS IS
A COMMON OCCURRENCE FOR US DURING THE COLD SEASON AND GENERALLY
MEANS THE CONVECTION AHEAD OF THE FRONT BECOMES LESS ORGANIZED WITH
TIME AS THE LOW LEVEL FOCUS DIMINISHES. THIS WILL HAPPEN HERE...BUT
WITH AT LEAST SOME WEAK LINGERING DEEP LAYER FORCING FOR
ASCENT...FEEL KEEPING CHANCE POPS IN THE FORECAST FOR ALL ZONES IN
THE MORNING IS APPROPRIATE...BUT WILL REMOVE THUNDER MENTION. AS THE
FRONT SLIPS SOUTH OF I-4 DURING THE AFTERNOON WILL REMOVE POPS FOR
THE TAMPA BAY AND NATURE COAST ZONES...AND THEN REMOVE ALL RAIN
CHANCES FURTHER SOUTH BY SUNDOWN SUNDAY EVENING. SKIES WILL ALSO
CLEAR FROM NORTH TO SOUTH DURING THE SECOND HALF OF SUNDAY AND
SUNDAY NIGHT. A COLDER AND MUCH DRIER AIRMASS WILL ARRIVE SUNDAY
NIGHT IN THE WAKE OF THE FRONT. IN GENERAL MOS GUIDANCE IS TOO COLD
ON THESE ADVECTION NIGHTS DIRECTLY BEHIND A FRONT...AND HAVE RAISED
A MAV/MET BLEND BY SEVERAL DEGREES FOR THE CURRENT LOW TEMPERATURE
FORECAST. AFTER THE ADJUSTMENT WE ARE LEFT WITH UPPER 30S AROUND
CHIEFLAND...RANGING DOWN TO AROUND 50 FOR I-4...AND MIDDLE/UPPER 50S
FOR FORT MYERS.
MONDAY...THE FIRST DAY OF THE NEW WORK WEEK LOOKS TO BE A
PLEASANT...SUNNY AND SEASONABLY COOL DAY AS HIGH PRESSURE BUILDS
EAST ALONG THE NORTHERN GULF COAST AND SUBSIDENCE EXPANDS OVERHEAD.
ENJOY YOUR SATURDAY!
&&
.LONG TERM (MONDAY NIGHT THROUGH NEXT FRIDAY)...
COOLER AND DRIER HIGH PRESSURE FROM THE NORTHERN GULF REGION WILL BE
IN PLACE ACROSS THE AREA KEEPING A GENERALLY N/NE FLOW IN PLACE
THROUGH TUESDAY. THE HIGH PRESSURE CENTER THEN SLOWLY SHIFTS TO THE
NORTHEAST ACROSS THE SOUTHEASTERN STATES TUESDAY NIGHT THROUGH
THURSDAY SHIFTING WINDS TO THE NE AND EAST ALLOWING MOISTURE AND
TEMPERATURES TO MODERATE. THE HIGH CENTER SHIFTS OFFSHORE OVER THE
WEST ATLANTIC FOR THURSDAY NIGHT AND FRIDAY WITH WINDS SHIFTING TO
THE E/SE AND A SLIGHT CHANCE OF RAIN POSSIBLE WITH THE INCREASED
MOISTURE FOR FRIDAY AFTERNOON MAINLY ACROSS THE SOUTH. TEMPERATURES
WILL BEGIN BELOW NORMAL FOR MONDAY NIGHT...THEN NEAR NORMAL TUESDAY
THROUGH WEDNESDAY NIGHT...AND RISING ABOVE NORMAL THROUGH THE REST
OF THE PERIOD.
&&
.AVIATION...
MVFR CEILINGS ARE EXPECTED TO DEVELOP ACROSS THE AREA OVER THE NEXT
COUPLE OF HOURS BEFORE SUNRISE WITH SOME PATCHY FOG ALSO POSSIBLE
MAINLY AT THE KLAL AND KPGD TERMINALS. CONDITIONS SHOULD LIFT BY 15Z
WITH VFR THEN EXPECTED THROUGH THE REST OF THE PERIOD. A COUPLE OF
SHOWERS WILL BE POSSIBLE IN THE LATE AFTERNOON/EARLY EVENING ACROSS
THE NORTHERN TERMINALS...BUT CHANCES ARE CURRENTLY TOO LOW TO
INCLUDE IN THE TAF.
&&
.MARINE...
HIGH PRESSURE MOVES AWAY FROM THE REGION AS A COLD FRONT APPROACHES
FROM THE WEST LATER TODAY AND TONIGHT. CAUTIONARY LEVEL WINDS AWAY
FROM SHORE TODAY WILL SHIFT TO MARINE ZONES MAINLY NORTH OF TARPON
SPRINGS BY TONIGHT. THE COLD FRONT WILL PUSH NORTHWEST TO SOUTHEAST
ACROSS THE EASTERN GULF ON SUNDAY WITH A WINDS SHIFT FROM SOUTHWEST
TO NORTHWEST AND NORTH. A PERIOD OF CAUTIONARY TO LOW END ADVISORY
LEVEL WINDS FROM THE NORTH IS ANTICIPATED FOR LATER SUNDAY INTO
MONDAY. SHOWERS AND THUNDERSTORMS WILL BECOME NUMEROUS TO WIDESPREAD
IN NATURE LATER TODAY INTO TONIGHT FROM TARPON SPRINGS NORTHWARD AND
SCATTERED IN NATURE FURTHER SOUTH. SHOWERS WILL CLEAR FROM NORTH TO
SOUTH ON SUNDAY WITH THE FRONTAL PASSAGE.
&&
.FIRE WEATHER...
ABUNDANT LOW LEVEL MOISTURE AHEAD OF AN APPROACHING COLD FRONT WILL
KEEP RELATIVE HUMIDITY VALUES WELL ABOVE CRITICAL LEVELS TODAY
DESPITE UNSEASONABLY WARM TEMPERATURES. WINDS WILL BE SOMEWHAT GUSTY
FROM THE SOUTHEAST AND SOUTH THROUGH THE DAY WITH MODERATE TO HIGH
DISPERSION INDICES. A COLD FRONT WILL SHIFT SOUTH ACROSS THE REGION
WITH A WIND SHIFT TO THE NORTHWEST IN ITS WAKE ON SUNDAY. THE MAIN
ARRIVAL OF DRIER AIR IS NOT EXPECTED UNTIL SUNDAY NIGHT AND MONDAY
AND NO FIRE WEATHER CONCERNS ARE ANTICIPATED FOR SUNDAY. WITH THE
DRIER AIR IN PLACE BY MONDAY...RELATIVE HUMIDITY VALUES ARE
CURRENTLY ANTICIPATED TO BRIEFLY REACH CRITICAL LEVELS FOR MUCH OF
THE AREA.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 81 69 76 52 / 20 60 50 0
FMY 83 69 82 59 / 10 20 40 10
GIF 82 67 77 50 / 20 40 50 0
SRQ 80 69 76 55 / 10 40 50 0
BKV 82 67 74 46 / 30 60 50 0
SPG 80 69 74 56 / 20 50 50 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WEATHER...MROCZKA
LONG TERM/AVIATION...COLSON
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
345 AM EST SAT DEC 14 2013
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A UPPER LEVEL PATTERN IN
THE PROCESS OF TRANSITIONING FROM A GENERALLY ZONAL PATTERN OVER THE
EASTERN CONUS TO A PATTERN DOMINATED BY LONGWAVE TROUGHING. THE
LEADING IMPULSES IN THIS TRANSITION IS A STRONG SHORTWAVE EJECTING
EASTWARD FROM THE MID/LOWER MS VALLEY EARLY THIS MORNING TOWARD THE
TN VALLEY AND CAROLINAS. A SECONDARY SHORTWAVE AND IMPULSE IS
FOLLOWING CLOSE BEHIND OVER THE SOUTHERN PLAINS. THIS FIRST
SHORTWAVE WILL PASS WELL TO OUR NORTH DURING THE LATER MORNING
HOURS...AND THEN THE SECOND IMPULSE WILL MAKE A CLOSER PASS ALONG
THE NORTHERN GULF COAST TONIGHT AND SUNDAY. WV IMAGERY SHOWS LOTS OF
UPPER LEVEL MOISTURE STREAMING EASTWARD AHEAD OF THESE SYSTEMS
ACROSS THE GULF OF MEXICO AND FLORIDA PENINSULA. WV IMAGERY ALSO
SHOWS STRONG SUBSIDENCE/DRYING IN THE WAKE OF THIS LEAD
IMPULSE...HOWEVER THIS SUBSIDENCE WILL BYPASS WELL TO OUR NORTH AND
WE WILL NEED TO WAIT UNTIL THE WAKE OF THE SECONDARY SHORTWAVE LATER
SUNDAY AND SUNDAY NIGHT TO FINALLY CLEAR OUR SKIES ONCE AGAIN.
AT THE SURFACE...1028MB HIGH PRESSURE IS LETTING UP ITS INFLUENCE ON
THE FL PENINSULA THIS MORNING AS IT SLIDES EASTWARD INTO THE WESTERN
ATLANTIC IN RESPONSE TO A WAVE OF LOW PRESSURE MOVING EASTWARD FROM
THE LOWER MS VALLEY. A COLD FRONT CURRENTLY EXTENDS SOUTHWARD FROM
THIS FEATURE INTO THE WESTERN GULF OF MEXICO AND WILL BE MOVING
EASTWARD ACROSS THE GULF THROUGH THE DAY. SEEING A MUCH WARMER EARLY
MORNING THAN 24 HOURS AGO WITH MOST LOCATIONS HOLDING IN THE 50S AND
60S AS EAST AND SOUTHEASTERLY LOW LEVEL FLOW CONTINUES TO ADVECT
ATLANTIC MOISTURE ACROSS THE REGION.
&&
.SHORT TERM (TODAY THROUGH MONDAY)...
TODAY...FORECAST PHILOSOPHY HAS NOT CHANGED MUCH IN TERMS OF THE
SENSIBLE WEATHER AND TIMING OF THE FRONT AND FORCING MECHANISM
THROUGH THE NEXT 24 HOURS. AS THE LEAD SHORTWAVE PIVOTS
NORTHEASTWARD THROUGH THE DAY IT WILL DRAW THE SURFACE LOW
REFLECTION TO THE NORTHEAST AS WELL. THIS SURFACE FEATURE SHOULD
REACH THE EASTERN CAROLINAS AROUND SUNDOWN THIS EVENING WITH THE
COLD FRONT TRAILING BACK THROUGH GA TO THE FL PANHANDLE AND
NORTH-CENTRAL GULF. INITIAL "BATCH" OF DEEP LAYER QG-FORCING MISSES
THE REGION TO THE NORTH...AND THE SECOND ROUND OF FORCING AHEAD OF
THE SECOND SHORTWAVE DOES NOT BEGIN TO ARRIVE OVER OUR NORTHERN
ZONES UNTIL LATE TODAY AND THIS EVENING. THIS SYNOPTIC FORCING IS
ALSO NOT COMPLIMENTED BY ANY DECENT RRQ JET DYNAMICS UNTIL THIS
EVENING AND OVERNIGHT. WITH THE LOW LEVEL FOCUS OF THE FRONT MAINLY
TO OUR WEST ALL DAY AND THE LATE ARRIVAL OF THE UPPER FORCING...
STILL EXPECT MUCH OF THE FORECAST AREA TO SEE A GENERALLY DRY DAY.
DO BRING SCATTERED SHOWERS INTO THE NORTHERN NATURE COAST ZONES
AFTER 1-2PM...BUT DO NOT RAISE RAIN CHANCES TO LIKELY UNTIL AFTER
4-5PM. RAIN CHANCES WILL QUICKLY DECREASE SOUTHWARD TO THE I-4
CORRIDOR DURING THE LATER AFTERNOON HOURS...AND JUST HAVE ISOLATED
SHOWERS IN THE FORECAST FOR THE EARLY EVENING AROUND TAMPA BAY. FAR
REMOVED FROM THE FORCING LATER TODAY...AREAS SOUTH OF TAMPA BAY SHOW
A 10% POP OR LESS. IT WILL BE VERY WARM DECEMBER DAY WITHIN THE
THERMAL RIDGE AHEAD OF THE FRONT. THIS THERMAL RIDGE COMBINED WITH
DECENT DIURNAL MIXING WILL ALLOW MANY SPOTS TO REACH THE LOWER
80S...AND EVEN SOME MIDDLE 80S FOR THE SOUTHERN ZONES. BIGGER
QUESTION ON TEMPS WILL BE NORTH OF TAMPA BAY WHERE CLOUDS WILL
THICKEN/LOWER SOONER.
TONIGHT...SECONDARY SHORTWAVE QUICKLY HELPS TO EVOLVE/DEEPEN THE
LONGWAVE TROUGH OVER THE EASTERN CONUS TONIGHT...AND THE APPROACH OF
THIS ENERGY TO THE ATLANTIC COAST IS PROGGED TO RESULT IN RAPID
CYCLOGENESIS ALONG THE MID-ATLANTIC/NEW ENGLAND BAROCLINIC ZONE.
GFS/ECMWF STILL BOTH SHOW A DECENT SWATH OF QG-FORCING OVERSPREADING
THE NORTHERN HALF OF THE PENINSULA THIS EVENING AND OVERNIGHT...BUT
WITH TIME THE MAIN ENERGY WILL BEGIN TO TRANSLATE NORTHWARD TOWARD
THE DEEPENING SYSTEM OFF THE MID-ATLANTIC COAST. THE COLD FRONT IS
NOT THE FASTEST OF MOVING FEATURES AND TAKES MOST OF THE OVERNIGHT
TO REACH LEVY COUNTY AND THE NORTHERN MARINE ZONES. WITH THE MAIN
LOW LEVEL AND UPPER FORCING OVER THE NORTHERN PENINSULA...WILL SHOW
A FAIRLY TIGHT POP GRADIENT FROM CHANCE 40-55% POPS ALONG THE I-4
CORRIDOR TO CATEGORICAL 80-90% POPS UP TOWARD CITRUS/LEVY COUNTY.
FURTHER SOUTH FROM I-4...RAIN CHANCES DIMINISH QUICKLY AND LOOKING
FOR A MAINLY DRY OVERNIGHT FOR PLACES LIKE PUNTA GORDA AND FORT
MYERS OVER INTO HIGHLANDS COUNTY. 35-40KT LOW LEVEL JET MAY RESULT
IN A FEW STRONGER WIND GUSTS FOR LEVY COUNTY ASSOCIATED WITH ANY
STORMS...BUT THE OVERALL THREAT FOR SEVERE WEATHER APPEARS MARGINAL.
DEEP SOUTHWEST FLOW AHEAD OF THE FRONT WILL KEEP IT A WARM DECEMBER
NIGHT WITH LOW TEMPS FAILING TO FALL OUT OF THE MIDDLE AND UPPER
60S.
SUNDAY/SUNDAY NIGHT...
COLD FRONT BECOMES INCREASINGLY STRETCHED AS THE LOW NEAR NEW
ENGLAND DEEPENS AND QUICKLY MOVES NORTHEAST THROUGH THE DAY. THIS IS
A COMMON OCCURRENCE FOR US DURING THE COLD SEASON AND GENERALLY
MEANS THE CONVECTION AHEAD OF THE FRONT BECOMES LESS ORGANIZED WITH
TIME AS THE LOW LEVEL FOCUS DIMINISHES. THIS WILL HAPPEN HERE...BUT
WITH AT LEAST SOME WEAK LINGERING DEEP LAYER FORCING FOR
ASCENT...FEEL KEEPING CHANCE POPS IN THE FORECAST FOR ALL ZONES IN
THE MORNING IS APPROPRIATE...BUT WILL REMOVE THUNDER MENTION. AS THE
FRONT SLIPS SOUTH OF I-4 DURING THE AFTERNOON WILL REMOVE POPS FOR
THE TAMPA BAY AND NATURE COAST ZONES...AND THEN REMOVE ALL RAIN
CHANCES FURTHER SOUTH BY SUNDOWN SUNDAY EVENING. SKIES WILL ALSO
CLEAR FROM NORTH TO SOUTH DURING THE SECOND HALF OF SUNDAY AND
SUNDAY NIGHT. A COLDER AND MUCH DRIER AIRMASS WILL ARRIVE SUNDAY
NIGHT IN THE WAKE OF THE FRONT. IN GENERAL MOS GUIDANCE IS TOO COLD
ON THESE ADVECTION NIGHTS DIRECTLY BEHIND A FRONT...AND HAVE RAISED
A MAV/MET BLEND BY SEVERAL DEGREES FOR THE CURRENT LOW TEMPERATURE
FORECAST. AFTER THE ADJUSTMENT WE ARE LEFT WITH UPPER 30S AROUND
CHIEFLAND...RANGING DOWN TO AROUND 50 FOR I-4...AND MIDDLE/UPPER 50S
FOR FORT MYERS.
MONDAY...THE FIRST DAY OF THE NEW WORK WEEK LOOKS TO BE A
PLEASANT...SUNNY AND SEASONABLY COOL DAY AS HIGH PRESSURE BUILDS
EAST ALONG THE NORTHERN GULF COAST AND SUBSIDENCE EXPANDS OVERHEAD.
ENJOY YOUR SATURDAY!
&&
.LONG TERM (MONDAY NIGHT THROUGH NEXT FRIDAY)...
COOLER AND DRIER HIGH PRESSURE FROM THE NORTHERN GULF REGION WILL BE
IN PLACE ACROSS THE AREA KEEPING A GENERALLY N/NE FLOW IN PLACE
THROUGH TUESDAY. THE HIGH PRESSURE CENTER THEN SLOWLY SHIFTS TO THE
NORTHEAST ACROSS THE SOUTHEASTERN STATES TUESDAY NIGHT THROUGH
THURSDAY SHIFTING WINDS TO THE NE AND EAST ALLOWING MOISTURE AND
TEMPERATURES TO MODERATE. THE HIGH CENTER SHIFTS OFFSHORE OVER THE
WEST ATLANTIC FOR THURSDAY NIGHT AND FRIDAY WITH WINDS SHIFTING TO
THE E/SE AND A SLIGHT CHANCE OF RAIN POSSIBLE WITH THE INCREASED
MOISTURE FOR FRIDAY AFTERNOON MAINLY ACROSS THE SOUTH. TEMPERATURES
WILL BEGIN BELOW NORMAL FOR MONDAY NIGHT...THEN NEAR NORMAL TUESDAY
THROUGH WEDNESDAY NIGHT...AND RISING ABOVE NORMAL THROUGH THE REST
OF THE PERIOD.
&&
.AVIATION...
MVFR CEILINGS ARE EXPECTED TO DEVELOP ACROSS THE AREA OVER THE NEXT
COUPLE OF HOURS BEFORE SUNRISE WITH SOME PATCHY FOG ALSO POSSIBLE
MAINLY AT THE KLAL AND KPGD TERMINALS. CONDITIONS SHOULD LIFT BY 15Z
WITH VFR THEN EXPECTED THROUGH THE REST OF THE PERIOD. A COUPLE OF
SHOWERS WILL BE POSSIBLE IN THE LATE AFTERNOON/EARLY EVENING ACROSS
THE NORTHERN TERMINALS...BUT CHANCES ARE CURRENTLY TOO LOW TO
INCLUDE IN THE TAF.
&&
.MARINE...
HIGH PRESSURE MOVES AWAY FROM THE REGION AS A COLD FRONT APPROACHES
FROM THE WEST LATER TODAY AND TONIGHT. CAUTIONARY LEVEL WINDS AWAY
FROM SHORE TODAY WILL SHIFT TO MARINE ZONES MAINLY NORTH OF TARPON
SPRINGS BY TONIGHT. THE COLD FRONT WILL PUSH NORTHWEST TO SOUTHEAST
ACROSS THE EASTERN GULF ON SUNDAY WITH A WINDS SHIFT FROM SOUTHWEST
TO NORTHWEST AND NORTH. A PERIOD OF CAUTIONARY TO LOW END ADVISORY
LEVEL WINDS FROM THE NORTH IS ANTICIPATED FOR LATER SUNDAY INTO
MONDAY. SHOWERS AND THUNDERSTORMS WILL BECOME NUMEROUS TO WIDESPREAD
IN NATURE LATER TODAY INTO TONIGHT FROM TARPON SPRINGS NORTHWARD AND
SCATTERED IN NATURE FURTHER SOUTH. SHOWERS WILL CLEAR FROM NORTH TO
SOUTH ON SUNDAY WITH THE FRONTAL PASSAGE.
&&
.FIRE WEATHER...
ABUNDANT LOW LEVEL MOISTURE AHEAD OF AN APPROACHING COLD FRONT WILL
KEEP RELATIVE HUMIDITY VALUES WELL ABOVE CRITICAL LEVELS TODAY
DESPITE UNSEASONABLY WARM TEMPERATURES. WINDS WILL BE SOMEWHAT GUSTY
FROM THE SOUTHEAST AND SOUTH THROUGH THE DAY WITH MODERATE TO HIGH
DISPERSION INDICES. A COLD FRONT WILL SHIFT SOUTH ACROSS THE REGION
WITH A WIND SHIFT TO THE NORTHWEST IN ITS WAKE. THE MAIN ARRIVAL OF
DRIER IS NOT EXPECTED UNTIL SUNDAY NIGHT AND MONDAY AND NO FIRE
WEATHER CONCERNS ARE ANTICIPATED FOR SUNDAY. WITH THE DRIER AIR IN
PLACE BY MONDAY...RELATIVE HUMIDITY VALUES ARE CURRENTLY ANTICIPATED
TO BRIEFLY REACH CRITICAL LEVELS FOR MUCH OF THE AREA
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 81 69 76 52 / 20 60 50 0
FMY 83 69 82 59 / 10 20 40 10
GIF 82 67 77 50 / 20 40 50 0
SRQ 80 69 76 55 / 10 40 50 0
BKV 82 67 74 46 / 30 60 50 0
SPG 80 69 74 56 / 20 50 50 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WEATHER...MROCZKA
LONG TERM/AVIATION...COLSON
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1207 AM CST SAT DEC 14 2013
.DISCUSSION...
830 PM CST
NO BIG UPDATES TO GOING FORECAST WITH ALSO NO CHANGES TO CURRENT
HEADLINES IN PLACE.
LONGWAVE TROUGH CONTINUES TO SHIFT EAST THROUGH THE CENTRAL
CONUS...WITH SEVERAL LEAD WAVES LIFTING NORTHEAST OUT AHEAD OF IT.
ASSOCIATED FORCING AS WELL AS A GOOD WAA PUSH ALLOWED FOR LIGHT TO
MODERATE SNOW TO QUICKLY MOVE INTO AREAS SOUTH OF I-80 EARLY THIS
EVENING. HIGH AMOUNTS OF MOISTURE WERE PRESENT ON THE 00Z ILX
RAOB...WITH 0.74 INCH PWAT AND 4G/KG MIXING RATIO AT 700MB.
LOW/MID LEVEL CONVERGENCE OWING TO MID/LOW LEVEL BAROCLINIC ZONE
STRETCHED ACROSS NORTH CENTRAL ILLINOIS HAS ALSO AIDED IN THE
DEVELOPMENT OF SEVERAL SMALLER SCALE FEATURES OVER THE LAST HOUR.
THE VISIBILITY HAS GENERALLY STAYED IN THE 1-3SM RANGE...WHILE
FALLING UNDER ONE MILE IN THESE SMALLER HEAVIER BANDS. ALTHOUGH
THESE SMALLER FEATURES WILL LIKELY REMAIN OVER THE NEXT SEVERAL
HOURS...THEY HAVE REMAINED TRANSIENT WITH LOCATIONS ONLY OBSERVING
BRIEF PERIODS OF THIS HEAVIER SNOW.
EXPECT THIS LIGHT TO MODERATE SNOW TO SLOWLY LIFT NORTH WITH THE
I-88 CORRIDOR LIKELY OBSERVING SNOWFALL BY THE 930 PM CST TIME
FRAME. ALTHOUGH STRONGEST WAA APPEARS TO SHIFT TO THE EAST OF THE
CWA OVER THE NEXT SEVERAL HOURS...BROAD SCALE LIFT AS WELL AS
INCREASE IN LOW LEVEL FRONTOGENESIS IS EXPECTED TO HELP PERSIST
LIGHT/MODERATE SNOW AND EVEN PROVIDE BRIEF PERIODS OF HEAVIER
SNOW. THE STRONGEST MESOSCALE FORCING WILL PERSIST TONIGHT AND
REMAIN IN THE ADVISORY AND WARNING AREAS TONIGHT INTO SATURDAY
MORNING. HAD DEBATED ADDING LIVINGSTON/KANKAKEE/LAKE IN/PORTER
COUNTY IN THE WARNING...WITH THIS ANTICIPATED STRONGER FORCING.
ALTHOUGH...WITH ONLY AN ADDITIONAL INCH OR TWO TO THE GOING
TOTALS...HAVE DECIDED TO LEAVE THE ADVISORY GOING AND INSTEAD
INCREASE THE SNOW RANGE TO 4-7 INCHES. REST OF THE SNOW TOTALS IN
THE HEADLINES STILL APPEAR TO BE ON TRACK...WITH 5 TO 8 INCHES
STILL LIKELY IN THE WARNING AREA.
CONTINUE TO MONITOR A SEPARATE AREA OF DEVELOPING SNOW ACROSS
SOUTHERN WISCONSIN AND FAR NORTHERN ILLINOIS. OUTSIDE OF THE LAKE
EFFECT/ENHANCEMENT EXPECTED ACROSS THIS AREA...LATEST GUIDANCE
CONTINUES TO INDICATE ANOTHER AREA OF BETTER FRONTOGENITICAL
FORCING ACROSS SOUTHERN WISCONSIN. THIS FORCING COULD ACT TO
SLIGHTLY ENHANCE TOTALS MORE TOWARDS THE ILLINOIS/WISCONSIN
BORDER...WITH MAYBE MORE 1-3 INCHES COULD BE OBSERVED BY TOMORROW
MORNING. LAKE EFFECT/ENHANCEMENT FOR FAR NORTHEAST ILLINOIS HAS
SHOWN INCREASING TRENDS WITH LATEST GUIDANCE. ALTHOUGH NOT OVERLY
LARGE...THIS WAS ENOUGH TO INCREASE SNOW TOTALS SLIGHTLY. LOW
LEVEL CONVERGENCE INCREASES TOWARDS EARLY SATURDAY MORNING...AND
POSSIBLY LINGERS INTO SATURDAY AFTERNOON AS BOUNDARY LAYER FLOW
SLOWLY SHIFTS. WITH THIS POSSIBLY PROVIDING AN EXTENDED PERIOD OF
LIGHT SNOW...HAVE INCREASED SNOW TOTALS MORE TOWARDS 1-3 IN LAKE
IL...BUT HAVE STILL LEFT OUT OF THE ADVISORY AT THIS TIME.
ALTHOUGH AN ISOLATED 4 INCH REPORT CANNOT BE RULED OUT IN THIS
AREA...WAS NOT ENOUGH TO INCLUDE IN THE HEADLINE. ONCE AGAIN...THE
EXTENDED NATURE OF THIS LIGHT LAKE EFFECT SNOW COULD WARRANT
HIGHER TOTALS IN LAKE COUNTY IL AND POSSIBLY HEADLINE CHANGES
SATURDAY MORNING.
RODRIGUEZ
//PREV DISCUSSION...
319 PM CST
SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT...
NOT MUCH HAS CHANGED WITH THE CURRENT THINKING FOR TONIGHT AND
SATURDAY REGARDING SNOWFALL AMOUNTS AND PLACEMENT. THE CURRENT
WATER VAPOR IMAGERY CONTINUES TO INDICATE A DECENT DISTURBANCE
NEAR THE TEXAS PANHANDLE EARLY THIS AFTERNOON...WITH SEVERAL LEAD
DISTURBANCES ACROSS OK AND INTO WESTERN MO. PROFILER AND VWP DATA
ACROSS THE SOUTHERN PLAINS AND MID MISSISSIPPI VALLEY INDICATES
THAT AROUND 30KT OF SOUTHWESTERLY FLOW AROUND 850 MB HAS DEVELOPED
IN ASSOCIATION WITH THIS SYSTEM. THIS IS ALLOWING FOR SOME DECENT
MOISTURE TRANSPORT AND ISENTROPIC ASCENT ACROSS THE MISSOURI AND
WEST CENTRAL ILLINOIS THIS AFTERNOON. THIS HAS PRODUCED A GOOD
AREA OF PRECIPITATION ACROSS MISSOURI...ESPECIALLY ALONG THE
LEADING EDGE OF THE BETTER MOISTURE TRANSPORT.
I EXPECT THIS AREA OF PRECIP TO CONTINUE TO MOVE NORTHWARD AND TO
OVERSPREAD MOST AREAS ALONG AND SOUTH OF INTERSTATE 80 THROUGH THE
EVENING AS THE BETTER MOISTURE GETS DRAWN NORTHWARD IN ASSOCIATION
WITH THE APPROACHING SOUTHERN STREAM SYSTEM. IT APPEARS LIKELY THAT
A BAND OF MODERATE TO HEAVY SNOW WILL SET UP THIS EVENING ACROSS MY
SOUTHERN COUNTIES...IN ASSOCIATION WITH A DEVELOPING BAND OF
FRONTOGENESIS. THE ENHANCED FORCING FOR ASCENT WITHIN THE
FRONTOGENETIC CIRCULATION WILL ALLOW FOR SOME DECENT ASCENT WITHIN
THE DENDRITIC GROWTH ZONE. THIS ALONG WITH THE FACT THAT STEEP LAPSE
RATES AND -EPV EXITS WITHIN AND ABOVE THIS ZONE ALSO SUGGESTS THAT
THEIR WILL BE SOME FAIRLY EFFICIENT SNOWFALL PRODUCTION WITHIN THIS
BAND OF SNOW. WITH THIS IN MIND...IT APPEARS THAT SNOWFALL RATES
COULD APPROACH 1 INCH PER HOUR FOR A COUPLE HOUR PERIOD THIS
EVENING...ESPECIALLY TO THE SOUTH OF INTERSTATE 80 WITHIN AND NEAR
THE CURRENT WINTER STORM WARNING.
A SECOND AREA OF SNOW WILL BE FAVORED...MAINLY ACROSS SOUTHERN
WISCONSIN THIS EVENING AS A SECONDARY AXIS OF FRONTOGENESIS DEVELOPS
ALONG A BAROCLINIC RIBBON...AND COMBINES WITH INCREASING FLOW AND LOW
LEVEL CONVERGENCE OFF OF LAKE MICHIGAN. HOWEVER...MOST HIGH RES
GUIDANCE CONTINUES TO FAVOR AREAS NORTH OF THE ILLINOIS BOARDER.
THEREFORE...IT APPEARS MOST OF NORTHERN ILLINOIS WILL REMAIN SNOW
FREE...THROUGH AT LEAST MID TO LATE EVENING.
THE SNOW SHOULD BEGIN TO SPREAD NORTHWARD BY LATE THIS EVENING...AND
BEGIN IMPACTING MOST OF NORTHERN ILLINOIS BY OR SHORTLY AFTER
MIDNIGHT AS THE SURFACE INVERTED TROUGH BECOMES ORIENTED NORTH TO
SOUTH ACROSS THE AREA OVERNIGHT. THE SNOW WILL CONTINUE INTO
SATURDAY AS SOME LARGER SCALE SUPPORT FOR ASCENT OVERSPREADS THE
AREA IN ASSOCIATION WITH THE APPROACHING NORTHERN STREAM SHORT WAVE.
THIS COULD EVEN LEAD TO A BIT IN AN UPTICK TO THE SNOWFALL
INTENSITY...PARTICULARLY ACROSS EASTERN ILLINOIS AND NORTHWESTERN
INDIANA...WHERE MID LEVEL DEFORMATION WILL CONTINUE IN ASSOCIATION
WITH THE MID LEVEL CIRCULATION. THE SNOW WILL GRADUALLY END ACROSS
NORTHERN ILLINOIS AS THE FLOW TURNS NORTHWESTERLY. SOME LINGERING
LAKE EFFECT SNOW SHOWERS ARE POSSIBLE ACROSS NORTHWESTERN INDIANA
INTO SATURDAY EVENING.
THERE ARE SOME POSSIBILITIES FOR SOME LAKE ENHANCEMENT FOR AREAS
NEAR THE LAKE LATE TONIGHT AND INTO SATURDAY AS THE FLOW TURNS EAST
NORTHEASTWARD. HOWEVER...THERMODYNAMICS OVER THE LAKE DO NOT APPEAR
TO BE VERY FAVORABLE FOR ANY SIGNIFICANT LAKE ENHANCEMENT POTENTIAL.
DELTA T`S LOOK TO REMAIN AROUND 12 DEGREES CELSIUS AND EQUILIBRIUM
LEVELS NEVER APPEAR TO REACH INTO THE DENDRITIC GROWTH ZONE.
SO...OVERALL...IT STILL APPEARS SNOWFALL AMOUNTS WILL RANGE FROM
ABOUT 5 TO 8 INCHES ACROSS THE WARNING AREA...3 TO 6 INCHES IN THE
ADVISORY AREAS...AND 2 TO 3 INCHES AROUND NORTHEASTERN
ILLINOIS...AND AN INCH OR LESS ACROSS NORTH CENTRAL ILLINOIS.
ONCE THE SNOW ENDS...THE NORTHWESTERLY FLOW WILL ALLOW COLDER AIR
TO SPILL BACK ACROSS THE REGION SETTING UP ANOTHER COLD SUNDAY
MORNING.
KJB
MEDIUM-LONG RANGE...SUNDAY THROUGH NEXT FRIDAY...
HIGHLIGHTS OF THE MEDIUM-LONG RANGE FORECAST PERIOD ARE CONTINUED
NORTHWEST UPPER FLOW WITH A PARADE OF WEAK CLIPPER SYSTEMS INTO
MID-WEEK...THEN A SHIFT TOWARD SOUTHWEST FLOW ALOFT MID/LATE NEXT
WEEK AS UPPER RIDGE BUILDS ACROSS THE EASTERN PACIFIC AND GULF OF
ALASKA AND INDUCES DOWNSTREAM LONG WAVE TROUGH ACROSS WESTERN NORTH
AMERICA. THIS WILL SUPPORT A TRANSITION FROM BELOW NORMAL TEMPS
SUN-WED...WITH THE POTENTIAL FOR A BRIEF WARM-UP THURS-EARLY FRI
AHEAD OF WESTERN TROUGH.
SUNDAY THROUGH WEDNESDAY...
MID-LEVEL SHORT WAVE TROUGH AXIS ASSOCIATED WITH EARLY WEEKEND
WINTER STORM WILL BE WELL EAST OF THE REGION BY SUNDAY MORNING.
MID/UPPER LEVEL LOW OVER DEVELOPS OVER ONTARIO AND THE NORTHERN
LAKES HOWEVER...WITH REGION OF ENHANCED NORTHWEST FLOW ALOFT FROM
THE NORTHERN PLAINS TO THE MIDWEST. SEVERAL MINOR AMPLITUDE RIPPLES
ARE INDICATED IN MODEL GUIDANCE WHICH PROPAGATE ALONG LOW LEVEL
BAROCLINIC ZONE WHICH STRETCHES NORTHWEST-SOUTHEAST ACROSS THE
REGION. SOME TIMING DIFFERENCES WITH THE MORE SUBTLE DISTURBANCES
BETWEEN MODELS...THOUGH IT APPEARS A WEAK WAVE WILL TRAVERSE THE
AREA SUNDAY WITH A SOMEWHAT BETTER DEFINED VORT MOVING OVER THE AREA
SUNDAY NIGHT AND EARLY MONDAY. FORECAST SOUNDINGS AND TIME/HEIGHT
DEPICTIONS INDICATE GENERALLY DRY MOISTURE PROFILES...WITH ONLY A
POCKET OF DEEPER MID-LEVEL MOISTURE SUNDAY NIGHT-EARLY MONDAY WITH
ISENTROPIC FORCING AHEAD OF THE STRONGER WAVE. THUS THE BEST
POTENTIAL FOR A LITTLE LIGHT SNOW APPEARS BE SUNDAY NIGHT...THOUGH
WITH LITTLE ACCUMULATION EXPECTED (A DUSTING TO PERHAPS A HALF INCH)
AS LIFT APPEARS GENERALLY WEAK AND WELL BELOW THE DENDRITIC GROWTH
ZONE. WEAK ASCENT LINGERS INTO MONDAY...ESPECIALLY ACROSS THE
NORTHEAST/EAST PARTS OF THE CWA WITH THE LEFT EXIT REGION OF THE
UPPER JET STREAK HELPING TO MAINTAIN SOME LARGE SCALE SUPPORT DURING
THE DAY. A MORE AMPLIFIED SHORT WAVE IS PROGGED TO DIG ACROSS THE
WESTERN GREAT LAKES REGION ON TUESDAY...THOUGH THE BEST WARM
ADVECTION AND ISENTROPIC UPGLIDE APPEARS TO REMAIN JUST TO THE
NORTH/NORTHEAST OF THE CWA...THOUGH A REINFORCING PUSH OF COLDER AIR
DOES ARRIVE TUESDAY NIGHT WITH A COLD FRONT.
COLDEST CONDITIONS LOOK TO OCCUR SUNDAY BEHIND THE EARLY WEEKEND
WINTER STORM...WITH HIGHS IN THE TEENS AND LOWS IN THE SINGLE DIGITS
TO AROUND 10 ABOVE. SOME MODERATION OCCURS MON-TUE WITH THE WEAK BUT
NEARLY PERSISTENT WARM ADVECTION ASSOCIATED WITH THE AFOREMENTIONED
CLIPPERS. A LITTLE COOLER TUESDAY NIGHT-WEDNESDAY BEHIND TUESDAY
NIGHTS COLD FRONT.
AS INDICATED ABOVE...DEVELOPING UPPER RIDGING OVER THE EAST PACIFIC
AND TROUGH INDUCEMENT OVER THE WESTERN CONUS WEDNESDAY-THURSDAY
RESULTS IN SURFACE LOW PRESSURE DEVELOPMENT OVER THE PLAINS BY EARLY
THURSDAY. FAIRLY DECENT MODEL AGREEMENT IN THIS LOW DEEPENING AND
LIFTING NORTHEAST ACROSS MINNESOTA AND THE NORTHERN GREAT LAKES
THURSDAY AND THURSDAY NIGHT...PLACING WFO LOT CWA IN THE WARM SECTOR
AS WARM FRONT LIFTS NORTH. SHALLOW COLD SURFACE LAYER MAY RESULT IN
A LITTLE MIXED PRECIPITATION THURSDAY MORNING ESPECIALLY NORTH AS
WARMING OCCURS MORE VIGOROUSLY ALOFT...THOUGH GFS/ECMWF RUNS
INDICATE THAT LOW LEVELS WARM ENOUGH TO PRODUCE MAINLY RAIN BY
THURSDAY EVENING/NIGHT. SOME TIMING DIFFERENCES DO ARISE WITH THE
NEW 12Z ECMWF (THE 00Z RUN WAS IN BETTER AGREEMENT WITH THE 00/12Z
GFS AND ENSEMBLE MEMBERS)...WITH THE ECMWF FASTER WITH THE LOW
LIFTING ACROSS THE NORTHERN LAKES EARLY FRIDAY AND BRINGING THE
TRAILING COLD FRONT THROUGH FASTER. CONTINUE TO FAVOR A SLIGHTLY
SLOWER SOLUTION SIMILAR TO THE 00Z EC/12Z GFS AND GEFS RUNS. THIS
WOULD SUPPORT TEMPS POTENTIALLY WARMING INTO THE 35-40 F RANGE
THURSDAY AND POTENTIALLY INTO THE 40S/EVEN 50 ACROSS THE SOUTHEAST
FRIDAY PRIOR TO COLD FRONTAL PASSAGE. PRECIP POTENTIAL APPEARS TO BE
GREATEST ALONG/AHEAD OF THE COLD FRONT INTO FRIDAY. DECREASING
THICKNESSES IN COLDER AIR BEHIND THE FRONT PORTEND A CHANGE BACK TO
SNOW FROM THE WEST FRIDAY.
THINGS LOOK POTENTIALLY INTERESTING JUST BEYOND THE END OF DAY
7...AS SOUTHWEST-NORTHEAST ORIENTED BAROCLINIC ZONE COULD BECOME THE
FOCUS FOR A COUPLE OF ROUNDS OF WINTRY PRECIP SOMEWHERE FROM HERE
INTO THE OHIO VALLEY...WHILE HIGH PRESSURE AND A RETURN TO
SUB-AVERAGE TEMPS BUILD BACK ACROSS THE UPPER MIDWEST.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* LGT SNOW WILL PERSIST THROUGH EARLY AFTN. PERIOD OF MODERATE
SNOW BETWEEN 08-11Z.
* CIGS STEADILY LOWER TO ARND IFR...WITH A PERIOD OF LIFT PSBL
WITH THE MOD SNOW. THEN IFR CONDS PERSIST THRU MID-AFTN.
* E/NE WINDS 08-11KT THRU 16Z...THEN WINDS TURNS NE TO N LATE
AFTN/EVE.
BEACHLER
//DISCUSSION...UPDATED 06Z...
WINTER STORM CONTINUES TO ROTATE ACROSS THE REGION...SPREADING LGT
SNOW ACROSS NORTHERN IL/NORTHWEST IN AIRFIELDS. THE IFR CONDS HAVE
BEEN HOLDING FURTHER SOUTH OF ORD AT MDW...HOWEVER EXPECT OVER THE
NEXT COUPLE OF HOURS THIS LINE TO LIFT NORTH AND ORD WILL SEE IFR
CONDS DEVELOP. GUIDANCE CONTINUES TO INDICATE A BURST OF MODERATE
TO POSSIBLY A BRIEF HVY SNOW BETWEEN 08-11Z. IFR CONDS WILL THEN
PREVAIL AT MOST TAF SITES...WITH THE EXCEPTION OF RFD WHICH WILL
REMAIN JUST NORTHWEST OF THE STEADIER SNOW. AS THE LOW PRESSURE
LIFTS NORTHEAST...WINDS WILL STEADILY TURN NORTHEAST THEN
NORTHWEST. AS WINDS TURN NORTHEAST TO NORTHWEST THE PRECIP WILL
STEADILY PUSH EAST...AND BRING A SLOW IMPROVEMENT TO THE IFR CONDS
TO MVFR CIGS BY 00Z SUN.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN SNOW PERSISTING THRU EARLY AFTN.
* MEDIUM CONFIDENCE IN SNOW INTENSITY.
* MEDIUM/HIGH CONFIDENCE DURATION OF IFR WILL BE LONGER AT MDW.
* HIGH CONFIDENCE IN WIND DIR/SPEED.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...MVFR WITH A CHC OF SNOW.
MONDAY...SLIGHT CHC OF SNOW.
TUESDAY-WEDNESDAY...VFR LIKELY.
THURSDAY...CHC OF RAIN OR SNOW.
MTF
&&
.MARINE...
144 PM CST
A LARGE AREA OF HIGH PRESSURE IS SETTLING OVER THE SERN CONUS AS WEAK
LOW PRESSURE MOVING ACROSS NRN NEW ENGLAND DAGS A COLD FRONT DOWN
LAKE MICHIGAN. THE FRONT HAS STALLED OUT OVER THE SOUTHERN TIP OF
THE LAKE LEADING TO LIGHT AND VARIABLE WINDS OVER THE SOUTHERN TIP
OF THE LAKE. NORTH WINDS ARE STRENGTHENING OVER THE NORTHERN
PORTIONS OF THE LAKE AS ANOTHER AREA OF ARCTIC HIGH PRESSURE BUILDS
OUT OF CANADA AND SPREADS ACROSS THE NRN PLAINS AND UPPER GREAT
LAKES. THE FRONT OVER THE SRN PORTIONS OF THE LAKE WILL WASH OUT AS
A DOUBLE BARRELED LOW PRESSURE SYSTEM DEVELOPS OVER THE SRN AND
CNTRL PLAINS. THE COMPLEX LOW PRESSURE SYSTEM WILL TRACK EWD THIS
EVENING WITH ONE CIRCULATION CENTER TRACKING THROUGH CNTRL IL AND
ANOTHER TRACKING THROUGH THE LOWER MISSISSIPPI VALLEY. A WEAK
INVERTED SFC TROUGH AXIS ASSOCIATED WITH THE MORE NORTHERN OF THE
TWO LOWS WILL MOVE ACROSS THE LAKE EARLY TOMORROW. AS THE HIGH
BUILDS ACROSS THE UPPER GREAT LAKES THIS EVENING...WINDS OVER THE
ENTIRE LAKE WILL GRADUALLY TURN EASTERLY...BUT AS THE INVERTED
TROUGH AXIS CROSSES THE LAKE TOMORROW...WINDS OVER THE LAKE WILL
GRADUALLY BACK THROUGH NELY TO NORTHERLY TOMORROW EVENING AND THEN
THEN CONTINUE TO BACK TO NWLY BY LATE SATURDAY NIGHT AND EARLY
SUNDAY MORNING. AS COLDER AIR ASSOCIATED WITH THE ARCTIC HIGH IS
DRAWN OVER THE LAKE...THE STRONG COLD ADVECTION AND STRENGTHENING
PRESSURE GRADIENT WILL LEAD TO WINDS INCREASING TO AROUND 30KT
THROUGH THE DAY ON SUNDAY. WHILE GALES ARE NOT EXPECTED AT THIS
TIME...THE STRONG WINDS AND COLDER AIR WILL LEAD TO A CHANCE FOR
LIGHT TO MODERATE FREEZING SPRAY ON SUNDAY. THE BRISK NWLY WINDS
WILL PERSIST THROUGH SUNDAY NIGHT...AND THEN ANOTHER HIGH WILL BUILD
ACROSS LAKE MICHIGAN ON MONDAY...ALLOWING WINDS TO TEMPORARILY
SUBSIDE. AS THE HIGH MOVES OFF TO THE EAST ON TUESDAY...ANOTHER LOW
WILL TRACK ACROSS SCNTRL CANADA...LEADING TO INCREASING SWLY-WLY
WINDS BY TUESDAY...WHICH SHOULD PERSIST THROUGH THE MIDDLE OF NEXT
WEEK.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WARNING...ILZ033-ILZ039 UNTIL NOON SATURDAY.
WINTER WEATHER ADVISORY...ILZ014 UNTIL 6 PM SATURDAY.
WINTER WEATHER ADVISORY...ILZ019-ILZ021-ILZ022-ILZ023-ILZ032
UNTIL NOON SATURDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002 UNTIL NOON SATURDAY.
WINTER STORM WARNING...INZ010-INZ011-INZ019 UNTIL NOON SATURDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 3 PM SATURDAY.
SMALL CRAFT ADVISORY...LMZ741-LMZ742-LMZ743...3 AM SATURDAY TO 3
PM SATURDAY.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
1105 PM CST Fri Dec 13 2013
.DISCUSSION...
ISSUED 837 PM CST Fri Dec 13 2013
Have made some minor tweaks to grids and reworded some of the
precip type wording for this evening. Otherwise, no major changes
anticipated.
Lull between initial wave along front to our northwest and the
main area of diffluence associated with approaching southern
stream system is moving into the region southeast of I-55. As
precip over Arkansas moves northeast, snow will likely increase in
coverage and intensity again after midnight. Current snow amount
forecasts may be a bit overdone in this area, but hesitate to make
major changes with the second wave yet to come.
Somewhat concerned about the area northwest of the Illinois River.
2-3 inches have been reported across Fulton County to this point
and that area remains in the deformation area and near the surface
warm front. Would not be surprised if several reports approach 6
inches in that area.
Barker
&&
.AVIATION...
ISSUED 1105 PM CST Fri Dec 13 2013
Evolution of winter system preceding pretty much as expected.
After a brief period of mix and freezing rain earlier this evening
at KSPI and KDEC, precipitation has transitioned to all snow. Due
to the showery nature of the snow, vsbys will vary widely and will
have to cover generally through the rest of the night with
occasional vsbys down as low as 3/4SM. Would like to include more
detail, but impossible given nature of precipitation. Will keep at
least some mention of -SN around much of the day tomorrow until
the main wave axis moves through around 00z.
Upstream cigs are widespread IFR and will generally follow until
surface low moves east of the area 15-18z.
Warm front is bisecting terminals at 05z with KPIA in northeast
flow and the remainder of the sites continuing from 140-100
degrees. Latest model suite suggests that low will move along I-64
which should shift winds to 010-060 after 12z and then 300-350
degrees by 00z as the low pulls east.
Barker
&&
.PREV DISCUSSION...
ISSUED 205 PM CST Fri Dec 13 2013
Clouds continue to lower and thicken this afternoon ahead of the winter
storm system expected to affect our area tonight into Saturday. Already
seeing some light rain and sleet pushing into extreme southwest IL early
this afternoon as the upper level wave tracks across the southern Plains.
SHORT TERM...Tonight through Monday
Significant snowfall expected over parts of central through east
central Illinois tonight thru Saturday morning...but not much in
the way of strong winds with this particular storm system.
The main forecast challenge this period will be with snowfall totals
starting tonight thru early Saturday afternoon. Will continue to hold
on to the winter weather advisory with a few locations across central
thru east central Illinois edging close to 6 inches by the time the
snow tapers off to flurries Saturday afternoon. Forecast soundings,
at least for a few hours late this afternoon into early this evening,
continues to suggest a brief period of rain, sleet and possibly some
freezing rain over parts of west central Illinois before we see the
lower layers saturate and cool sufficiently enough to support mostly
snow thru the overnight hours. NAM-WRF time height cross sections
indicate the best forcing coupled with the deeper moisture/and dendritic
growth zone will be mainly tonight thru about 14z Saturday. Using a
13:1 SLR indicates 4 to 6 inches will be common across the area by the
time the snow diminishes on Saturday.
Still a bit concerned about the potential for banding, especially
along the inverted trof, which is expected to push across our area
early Saturday morning. Several of the hi-res models suggest the
threat is there but unfortunately, are not very consistent in depicting
the location. Past few runs of the HRRR have indicated one band to move
north across the area this evening, with a break over parts of central
thru east central IL around midnight, before another band pushes
acrs the area towards morning with the inverted trof. Wouldn`t at all
be surprised to see a few areas with 6 to 8 inches accumulation by late
Saturday morning, but at this time, the threat appears too isolated.
Models are a bit more consistent in showing an increase in snow totals
just to our east as the weak surface low and inverted trof shift off
to our east and we see a better coupled 250mb jet structure and
associated upper level divergence.
The upper level wave and surface reflection should push well off
to our east by late tomorrow afternoon with all of the precip shifting
out of the forecast area. The weather should be on the quiet side for
the rest of the short term period with a brief cool down in the wake
of the winter system Saturday night through Sunday night before we see
milder temperatures move into our area early next week.
LONG TERM...Tuesday through Friday
Medium range models indicate some fast moving waves approaching
our area from the northwest at the start of this forecast period
with little in the way of moisture available to produce much in
the way of precip in our area. The first such wave will move across
the lower Great Lakes on Monday with a hint for some very light
precip during the day, mainly to our north. The next wave moves
quickly southeast along the tight 850 mb baroclinic zone on Tue,
at least according to the latest ECMWF, with again little in the
way of moisture to work with. Will continue to keep the first part
of the week dry but could see some low chance pops added in later
forecasts.
Warmer temperatures expected in the Wed-Fri time frame as a deep
upper level trof drops southeast into the southern Rockies and
brings about a strong southwest flow aloft over our area. This
should result in mild temps, at least compared to what we have
been experiencing, through the end of the week. However, as the
deep upper level trof edges east into the central Plains, a strong
Arctic cold front will approach our area on Friday increasing the
precip chances Thursday night into Friday, followed by much colder
weather for next weekend.
Smith
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Noon CST Saturday FOR ILZ038-
042>046-051>057-061>063-066>068-071>073.
WINTER WEATHER ADVISORY until 6 AM CST Saturday FOR ILZ027>031-
036-037-040-041-047>050.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
810 PM EST SUN DEC 15 2013
.SYNOPSIS...
ISSUED AT 300 PM EST SUN DEC 15 2013
TONIGHT INTO MONDAY AND TUESDAY WILL FEATURE COLD CONDITIONS AND
SEVERAL CHANCES FOR LIGHT SNOW AS CLIPPER SYSTEMS TRACK SOUTHEAST
THROUGH THE AREA IN NORTHWEST FLOW. A WARMING TREND IS EXPECTED BY
MID TO LATE WEEK WITH RAIN POSSIBLE ALONG A COLD FRONT LATER
THURSDAY INTO FRIDAY.
&&
.UPDATE...
ISSUED AT 748 PM EST SUN DEC 15 2013
UPWARD NUDGE TO POPS ACRS FAR SWRN/SRN CWA OVERNIGHT WITH APPROACH
OF MID LEVEL 700-600MB JET STREAK ACRS ERN SD DIVES SEWD THROUGH
ERN IA/NCNTL IL TOWARD DAYBREAK. EFFECIENCY OF SEEDER/FEEDER
PROCESS AMID ARCTIC MODIFIED LOWER TROPOSPHERE. DECENT...ALBEIT
BRIEF SATURATION WITHIN THIN DGZ /10-13 KFT/ PER LATEST RAP BUFKIT
PROFILES...IN TANDEM WITH UPSTREAM RESPONSE...SUGGESTS HIR
POPS/CERTAINTY IN THIS AREA. LITTLE QPF/SNOWFALL MODIFICATIONS
GIVEN BREVITY OF EVENT.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY MORNING)
ISSUED AT 300 PM EST SUN DEC 15 2013
LAKE EFFECT SNOW SHOWERS AND LIGHT SNOW CHANCES ACROSS THE SOUTH
TONIGHT WITH WEAK CLIPPER SYSTEM THE MAIN ISSUES IN SHORT TERM
PERIOD.
COLD AIR ADVECTION AND NW FLOW ALLOWING FOR SCATTERED LAKE EFFECT
SNOW SHOWERS TODAY. THESE SHOULD CONTINUE INTO THE EVENING ACROSS
THE NORTH WITH FAVORABLE FLOW AND DELTA T VALUES IN MID TEENS.
LIMITING FACTOR WILL BE RELATIVELY SHALLOW MOISTURE AND INVERSION
HEIGHTS BELOW 4KFT. CONTINUATION OF PERSISTENT LIGHT ACTIVITY
EXPECTED WITH AN INCH OR TWO POSSIBLE TONIGHT. FLOW GRADUALLY BACKS
WITH CLIPPER PASSING BY TO SOUTH SO ACTIVITY SHOULD SHIFT NORTHWARD
WITH INLAND PENETRATION REDUCED.
CLIPPER SYSTEM OVER IA/MN THIS AFTERNOON WILL DIVE SOUTHEAST AND
MOVE THROUGH INDIANA OVERNIGHT. SOUTHERN CWA WILL BE ON NORTHERN
FRINGE OF MOISTURE AND WEAK LIFT. HIRES GUIDANCE INDICATING A FEW
HUNDREDTHS QPF WITH WEAK FORCING. HAVE KEPT POPS IN HIGH CHANCE
CATEGORY BUT WILL STOP SHORT OF LIKELY GIVEN WEAK NATURE AND
QUESTIONS WITH REGARDS TO SATURATION OF LOWER LEVELS AND NORTHERN
EXTENT OF PCPN. ANY ACCUMS LOOK TO BE AN INCH OR LESS.
TEMPERATURES WILL BE TRICKY WITH CLOUD COVER AND PARTIAL CLEARING
EXPECTED BETWEEN LAKE EFFECT CLOUD PLUME AND CLIPPER. ANY AREAS THAT
SEE CLEARING WILL SEE LARGE AND QUICK TEMP DROPS. WILL GO WITH A
BLEND OF LOWER OFFICIAL GRIDS AND LOWEST GUIDANCE GIVEN CLOUD COVER
UNCERTAINTY.
&&
.LONG TERM...(MONDAY AFTERNOON THROUGH SUNDAY)
ISSUED AT 300 PM EST SUN DEC 15 2013
COLD/ACTIVE WEST-NORTHWEST FLOW THROUGH MID-WEEK...BRIEF WARMING
TREND AND RAIN LATE WEEK...AND POTENTIAL FOR MORE SIGNIFICANT
WINTER STORM NEXT WEEKEND REMAIN HIGHLIGHTS THIS PERIOD...
POTENT WESTERN CANADA MID LEVEL SHORTWAVE TROUGH WILL AMPLIFY
SOUTHEAST INTO THE UPPER MIDWEST AND GREAT LAKES LATER MONDAY INTO
TUESDAY. WAA/SYSTEM RELATIVE ISENTROPIC ASCENT WITH LEAD PV
ANOMALY...COUPLED WITH LEFT EXIT ASSISTANCE FROM A 140-150 KT
UPPER JET DROPPING INTO THE NORTH-CENTRAL US...WILL LIKELY BRING A
3-5 HOUR PERIOD OF LIGHT SNOW TO NORTHERN TWO THIRDS OF FA LATE
MONDAY AFTERNOON INTO MONDAY EVENING. DECENT SNOW RATIOS OF
15-20:1 POSSIBLE WITH MODEL XSECTIONS/SOUNDINGS SHOWING OMEGA/FGEN
ALIGNED WITHIN 150 MB DEEP DGZ. LACKING MOISTURE AND QUICK
MOVEMENT DEFINITE LIMITING FACTORS FOR MORE SIGNIFICANT SNOW
ACCUMS...WITH CURRENT EXPECTATIONS FOR 1-3" NORTH OF US30...AROUND
AN INCH CENTRAL...AND LITTLE TO NO ACCUMULATION FAR SOUTH. A
SECOND VORT MAX LOOKS TO DROP THROUGH ON TUESDAY WITH ANOTHER
CHANCE FOR LIGHT SNOW ACCUMULATIONS...WITH LAKE EFFECT SNOW
SHOWERS POSSIBLE IN WAKE OF SYSTEM LATE TUESDAY-TUESDAY NIGHT.
WARMING TREND EXPECTED LATER WEDNESDAY THROUGH FRIDAY AS EASTERN
CONUS TROUGHING RELAXES AND UPPER TROUGH RELOADS ACROSS THE WEST.
THIS DEEP WESTERN CONUS TROUGH LOOKS TO FRACTURE WITH NORTHERN
STREAM WAVE PROPAGATING EAST INTO THE UPPER MIDWEST/GREAT LAKES
LATER THURSDAY-FRIDAY PER MODEL CONSENSUS. THE LOCAL AREA LOOKS TO
BE ON THE WARM/WET SIDE OF THIS SYSTEM WITH FRONTAL WAVE TRACK
NORTH THROUGH MICHIGAN. A BRIEF CHANGEOVER TO A WINTRY MIX STILL
APPEARS POSSIBLE BEFORE PRECIP ENDS LATE FRIDAY/FRIDAY NIGHT GIVEN
STRONG COLD ADVECTION UNDERCUT. PREFERENCE LIES WITH ECMWF/GEM/UKMET
SOLUTIONS FOR NEXT WEEKEND WITH POSSIBLE ICE/SNOW EVENT AS
SHORTWAVE ENERGY EVENTUALLY EJECTS OUT OF THE SOUTHWEST AND SPAWNS
A MORE FORMIDABLE SFC WAVE ALONG LEFTOVER OH VALLEY BAROCLINIC
ZONE.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 748 PM EST SUN DEC 15 2013
MVFR CIGS/ABOVE FUEL ALT AT KSBN TO GIVE WAY TO VFR AS BLYR WIND
FLOW CONTS TO BACK MORE SWRLY TOWARD DAYBREAK. OTHERWISE...
PRIMARY FOCUS ON RAPID DETERIORATION OF CONDS...ESPCLY WRT VSBYS
WITH NEXT UPSTREAM CLIPPER/SHORTWAVE TO ARRIVE LATE MON AFTN. IFR
MET CONDS APPEAR LIKELY AT KSBN. A BIT MORE OPTIMISTIC AT KFWA
WITH BOTH LATER TIMING AND THE POTNL THAT BULK OF SNOW STREAK TO
TRACK NORTH OF KFWA...LATER ISSUANCES WITH 00 UTC MODEL
INCORPORATION LKLY TO BETTER FOCUS ON ISSUE.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LMZ043-046.
&&
$$
UPDATE...MURPHY
SYNOPSIS...STEINWEDEL
SHORT TERM...LASHLEY
LONG TERM...STEINWEDEL
AVIATION...MURPHY
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AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
930 AM EST SAT DEC 14 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 356 AM EST SAT DEC 14 2013
ACCUMULATING SNOW WILL CONTINUE ACROSS MUCH OF THE FORECAST AREA
TODAY AS LOW PRESSURE TRACKS THROUGH THE OHIO VALLEY. ARCTIC AIR
WILL RETURN TONIGHT AS THE STORM MOVES AWAY TO THE EAST...WITH
CHILLY TEMPERATURES INTO THE EARLY PART OF THE WEEK. HIGH PRESSURE
WILL BRING DRY WEATHER AND A WARMING TREND THROUGH MIDWEEK.
UNSETTLED WEATHER RETURNS LATE THURSDAY AND FRIDAY AS LOW PRESSURE
TRACKS THROUGH THE REGION...WITH TEMPERATURES WARM ENOUGH FOR
PRECIPITATION TO FALL AS RAIN ACROSS CENTRAL INDIANA.
&&
.NEAR TERM /TODAY/...
ISSUED AT 356 AM EST SAT DEC 14 2013
COMPLEX WINTER STORM ONGOING ACROSS THE REGION EARLY THIS MORNING.
STEADIER SNOWS CONTINUE TO FALL OVER NORTHERN COUNTIES WITH A DRY
SLOT FURTHER SOUTH LIMITING PRECIP TO VERY LIGHT SNOW OR SHUTTING IT
OFF COMPLETELY ACROSS MUCH OF THE REST OF THE FORECAST AREA. BROADER
AREA OF HEAVIER PRECIPITATION QUICKLY EXPANDING NORTHEAST OUT OF THE
LOWER OHIO VALLEY. TEMPS WERE IN THE LOWER AND MIDDLE 30S AS OF 08Z.
DRY SLOT IS TAKING ITS TIME TO FILL IN...BUT EXPECT AREA OF HEAVIER
PRECIPITATION WILL EXPAND INTO THE FORECAST AREA OVER THE NEXT
SEVERAL HOURS WITH SNOWFALL COMMENCING ONCE AGAIN IN LOCATIONS WHERE
IT HAS STOPPED. RAP/NAM BOTH INDICATING A 50KT LOW LEVEL JET RIDING
UP THE MISSISSIPPI VALLEY AND CONTRIBUTING TO THE EXPANSION OF
PRECIP OVER THE LOWER OHIO VALLEY. THE LOW LEVEL JET WILL SHIFT EAST
ACROSS THE REGION AHEAD OF THE 850MB LOW THROUGH
MIDDAY...MAINTAINING A PLENTIFUL SURGE OF LOW LEVEL MOISTURE INTO
THE REGION. MAIN UPPER LEVEL WAVE LOCATED OVER SOUTHWEST MISSOURI
EARLY THIS MORNING WILL LIFT NORTHEAST ACROSS THE FORECAST AREA BY
EARLY AFTERNOON. SHORT RANGE MODEL GUIDANCE CONTINUING TO ADVERTISE
A DEFORMATION AXIS AND FRONTOGENETICAL FORCING WITHIN THE MID LEVELS
EXPANDING INTO THE FORECAST AREA PRIOR TO DAYBREAK AHEAD OF THE
UPPER WAVE.
ALL OF THESE FEATURES REMAIN SUPPORTIVE OF THE RESUMPTION OF
WIDESPREAD SNOW AND EXPECTATION FOR ADDITIONAL ACCUMULATIONS INTO
THE EARLY AFTERNOON...ESPECIALLY ACROSS THE NORTHERN HALF OF THE
FORECAST AREA. WITH THAT BEING SAID...TEMPERATURES WITHIN THE
BOUNDARY LAYER NEED TO BE MONITORED OVER THE NEXT SEVERAL HOURS AS
IMPACTS TO PRECIP TYPE OVER SOUTHERN COUNTIES AND SNOWFALL RATIOS IN
GENERAL ARE POSSIBLE. LAPS SOUNDINGS INDICATING A VERY SHALLOW LAYER
OF AIR NEAR THE SURFACE THAT SITS JUST ABOVE FREEZING OVER THE
SOUTHERN HALF OF THE FORECAST AREA WITH TEMPS AT 32-35F. WITH THE
LOW LEVEL JET TRANSPORTING SLIGHTLY WARMER BOUNDARY LAYER AIR NORTH
OVER THE NEXT FEW HOURS...EXPECTING SURFACE TEMPS TO MOVE LITTLE AND
MAY EVEN RISE A FEW DEGREES AFTER DAYBREAK. OVERALL...LOW LEVEL
THERMALS OVER THE NEXT SEVERAL HOURS REMAIN SUGGESTIVE OF SNOW AS
RATES INTENSIFY WITH THE EXPANSION OF THE PRECIP SHIELD. AS SLIGHTLY
WARMER AIR NOSES INTO SOUTHERN COUNTIES WITH THE LOW LEVEL JET AFTER
DAYBREAK HOWEVER...POTENTIAL FOR SOME LIGHT RAIN TO MIX IN WITH THE
SNOW. RAP AND NAM ARE THE MOST AGGRESSIVE WITH BRINGING THE 0C LINE
AT 850MB ACROSS THE SOUTHEASTERN HALF OF THE FORECAST AREA THROUGH
18Z...BOTH HINTING AT A TROWAL ROTATING INTO OUR SOUTHEAST AND
EASTERN COUNTIES. CONSIDERING RECENT TRENDS AND THE FACT THAT
SURFACE TEMPS ARE RUNNING A FEW DEGREES WARMER THAN PREVIOUSLY
THOUGHT...WILL BRING CHANCE FOR RAIN TO MIX IN WITH SNOW TO A
VINCENNES-BEDFORD-GREENSBURG LINE BY MID MORNING CONTINUING INTO
EARLY AFTERNOON.
CONSIDERING ABOVE THOUGHTS AND TAKING INTO ACCOUNT LIQUID TO
SNOWFALL RATIOS LIKELY REMAINING NEAR 10-1 FOR MUCH OF THE FORECAST
AREA FOR THE DURATION OF THE EVENT...HAVE TRIMMED TOTAL SNOWFALL
AMOUNTS A BIT OVER ALL BUT FAR NORTHERN SECTIONS. TOTAL SNOW ACCUMS
INCLUDING WHAT FELL SINCE FRIDAY EVENING STILL EXPECTED TO AROUND
6-7 INCHES OVER FAR NORTHERN COUNTIES...DIMINISHING TO 4-5 ALONG THE
I-70 CORRIDOR. FURTHER SOUTH...EXPECTING TOTALS GENERALLY AT 1-3
INCHES. THE NORTHWARD EXTENT OF THE ABOVE FREEZING AIR WITHIN THE
BOUNDARY LAYER AND THE POSSIBILITY OF ENHANCED FORCING IN THE
VICINITY OF A TROWAL COULD LEAD TO FURTHER ADJUSTMENTS IN THESE
AMOUNTS AND WILL CONTINUE TO MONITOR. THE WARNING AND ADVISORY WILL
CONTINUE IN THEIR CURRENT STATES THROUGH 23Z.
TEMPS...NEARLY STEADY TEMPS EXPECTED TODAY BUT IN GENERAL STILL FEEL
MOS IS TOO WARM WITH HIGHS. LEANED CLOSER TO CONSALL WITH TEMPS
RANGING FROM THE LOWER 30S NORTH TO MID 30S SOUTH.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
ISSUED AT 356 AM EST SAT DEC 14 2013
FORECAST CHALLENGES FOCUS ON MINOR SNOW CHANCES AND TEMPERATURES AS
COLDER AIR RETURNS FOR MUCH OF THE SHORT TERM.
ANY LINGERING LIGHT SNOW ON THE BACK SIDE OF THE DEPARTING SYSTEM
WILL END DURING THE EVENING...POSSIBLY AS A BRIEF PERIOD OF DRIZZLE
OR FREEZING DRIZZLE AS DRIER AIR DEEPENS ABOVE THE BOUNDARY LAYER.
LOW CLOUDS WILL PERSIST ALL NIGHT AS MOISTURE REMAINS TRAPPED
BENEATH A SHARP INVERSION.
THE PASSAGE OF TWO DEEP UPPER LOWS TO THE NORTH OF THE GREAT LAKES
WILL MAINTAIN BROAD TROUGHING ALOFT AND A GENERAL NORTHWEST FLOW
THROUGHOUT THE PERIOD. SEVERAL DISTURBANCES ALOFT WILL TRAVERSE THE
REGION MAINTAINING MOSTLY CLOUDY CONDITIONS AND BRINGING PERIODIC
LIGHT SNOW SHOWERS AND FLURRIES ACROSS MUCH OF THE FORECAST AREA.
FLURRIES ARE POSSIBLE WITHIN A BROAD CYCLONIC FLOW SUNDAY AND SUNDAY
NIGHT. STRONGER UPPER WAVE SET TO TRACK ACROSS THE LOWER GREAT LAKES
MONDAY AND WILL CARRY CHANCES FOR SNOW SHOWERS THROUGHOUT THE DAY.
SOUTHERLY FLOW WILL DEVELOP ON THE BACK SIDE OF A SURFACE HIGH
PRESSURE RIDGE BY MONDAY ALLOWING FOR WARM ADVECTION TO DEVELOP WITH
MODERATING TEMPS.
TEMPS...PREFER THE COLDER MAVMOS THROUGH MUCH OF THE PERIOD AS IT
APPEARS TO CAPTURE THE INFLUENCE FROM THE LEFTOVER SNOWPACK FROM
STORM TODAY BETTER. HIGHS WILL FALL BACK INTO THE LOWER/MIDDLE 20S
ON SUNDAY WITH STRONG COLD ADVECTION. THE SHIFT TO SOUTHERLY FLOW
MONDAY WILL ALLOW FOR A RECOVERY INTO THE 30S OVER SOUTHERN
COUNTIES. LOWS IN THE TEENS TONIGHT AND SUNDAY NIGHT WILL RECOVER
INTO THE 20S MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
ISSUED AT 357 AM EST SAT DEC 14 2013
THE EXTENDED PERIOD WILL START OUT WITH WEAK SHORTWAVES ROTATING
AROUND AN UPPER LOW OVER ONTARIO. THIS WILL RESULT IN LIGHT SNOW
SHOWERS OVER NORTHERN INDIANA. HOWEVER...CHOSE TO LEAVE PRECIP OUT
OF CENTRAL INDIANA ON TUESDAY SINCE BEST LIFT WILL BE NORTH OF
FORECAST AREA. DRY CONDITIONS WILL PREVAIL THROUGH MID-WEEK WITH
DECENT SUBSIDENCE ALOFT. HOWEVER...THE RIDGING OVER THE CENTRAL
U.S. WILL START TO BREAK DOWN BY THURSDAY AS A LOW PRESSURE SYSTEM
STRENGTHENS OVER THE WESTERN UNITED STATES. MEANWHILE...WARM AIR
WILL BE ADVECTED INTO CENTRAL INDIANA AHEAD OF A SURFACE
LOW...RESULTING IN ABOVE NORMAL TEMPERATURES. PRECIP ASSOCIATED
WITH THAT SURFACE LOW WILL INITIALLY FALL IN THE FORM OF RAIN ON
THURSDAY NIGHT AND FRIDAY...AND THEN TRANSITION TO A RAIN/SNOW MIX
AS COLDER AIR FILTERS IN BEHIND THE ASSOCIATED COLD FRONT.
&&
.AVIATION /DISCUSSION FOR THE 141500Z KIND TAF UPDATE/...
ISSUED AT 930 AM EST SAT DEC 14 2013
RADAR INDICATES HEAVIER PRECIPITATION MAY BE MOVING INTO THE KIND
AREA OVER THE NEXT HOUR OR SO. SURFACE REPORTS SUGGEST THE RAIN/SNOW
LINE IS GETTING CLOSE TO KIND...SO CONFIDENCE IN PRECIPITATION TYPE
FORECAST FOR THE NEXT SEVERAL HOURS IS LOW. APPEARS BASED ON DUAL
POL PRODUCTS THAT THE RAIN/SNOW LINE IS BEGINNING TO RETREAT AFTER
ADVANCING NORTH OVER THE PAST HOUR TO SO. FOR NOW...WILL KEEP ALL
SNOW IN THE FORECAST WITH POTENTIAL FOR PERIODS OF MODERATE SNOW
THROUGH THE EARLY AFTERNOON.
WILL BACK THE WIND FORECAST A BIT BASED ON CURRENT TRENDS. PREVIOUS
DISCUSSION FOLLOWS.
LIFR CONDITIONS CAN BE EXPECTED WELL INTO THIS AFTERNOON AS BANDS
OF SNOW CONTINUE TO PASS OVER TAF SITES. SNOW SHOWERS WILL WEAKEN
AFTER SAT 21Z AND THEN COME TO AN END AROUND SUN 00Z. MINIMAL
IMPROVEMENTS IN VISIBILITIES CAN BE EXPECTED BY THIS EVENING...BUT
DO NOT EXPECT CEILINGS TO IMPROVE TO MVFR CATEGORY UNTIL AFTER SUN
06Z. WINDS WILL BECOME NORTHWESTERLY THIS AFTERNOON AND STRENGTHEN
SLIGHTLY DURING THE EVENING HOURS WITH SUSTAINED SPEEDS OF
8 TO 12 KTS.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR
INZ053>057-060>065-067>072.
WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR INZ021-
028>031-035>049-051-052.
&&
$$
SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....TDUD
AVIATION...TDUD/JAS
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
WWW.TWITTER.COM/NWSINDIANAPOLIS
WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
627 AM EST SAT DEC 14 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 356 AM EST SAT DEC 14 2013
ACCUMULATING SNOW WILL CONTINUE ACROSS MUCH OF THE FORECAST AREA
TODAY AS LOW PRESSURE TRACKS THROUGH THE OHIO VALLEY. ARCTIC AIR
WILL RETURN TONIGHT AS THE STORM MOVES AWAY TO THE EAST...WITH
CHILLY TEMPERATURES INTO THE EARLY PART OF THE WEEK. HIGH PRESSURE
WILL BRING DRY WEATHER AND A WARMING TREND THROUGH MIDWEEK.
UNSETTLED WEATHER RETURNS LATE THURSDAY AND FRIDAY AS LOW PRESSURE
TRACKS THROUGH THE REGION...WITH TEMPERATURES WARM ENOUGH FOR
PRECIPITATION TO FALL AS RAIN ACROSS CENTRAL INDIANA.
&&
.NEAR TERM /TODAY/...
ISSUED AT 356 AM EST SAT DEC 14 2013
COMPLEX WINTER STORM ONGOING ACROSS THE REGION EARLY THIS MORNING.
STEADIER SNOWS CONTINUE TO FALL OVER NORTHERN COUNTIES WITH A DRY
SLOT FURTHER SOUTH LIMITING PRECIP TO VERY LIGHT SNOW OR SHUTTING IT
OFF COMPLETELY ACROSS MUCH OF THE REST OF THE FORECAST AREA. BROADER
AREA OF HEAVIER PRECIPITATION QUICKLY EXPANDING NORTHEAST OUT OF THE
LOWER OHIO VALLEY. TEMPS WERE IN THE LOWER AND MIDDLE 30S AS OF 08Z.
DRY SLOT IS TAKING ITS TIME TO FILL IN...BUT EXPECT AREA OF HEAVIER
PRECIPITATION WILL EXPAND INTO THE FORECAST AREA OVER THE NEXT
SEVERAL HOURS WITH SNOWFALL COMMENCING ONCE AGAIN IN LOCATIONS WHERE
IT HAS STOPPED. RAP/NAM BOTH INDICATING A 50KT LOW LEVEL JET RIDING
UP THE MISSISSIPPI VALLEY AND CONTRIBUTING TO THE EXPANSION OF
PRECIP OVER THE LOWER OHIO VALLEY. THE LOW LEVEL JET WILL SHIFT EAST
ACROSS THE REGION AHEAD OF THE 850MB LOW THROUGH
MIDDAY...MAINTAINING A PLENTIFUL SURGE OF LOW LEVEL MOISTURE INTO
THE REGION. MAIN UPPER LEVEL WAVE LOCATED OVER SOUTHWEST MISSOURI
EARLY THIS MORNING WILL LIFT NORTHEAST ACROSS THE FORECAST AREA BY
EARLY AFTERNOON. SHORT RANGE MODEL GUIDANCE CONTINUING TO ADVERTISE
A DEFORMATION AXIS AND FRONTOGENETICAL FORCING WITHIN THE MID LEVELS
EXPANDING INTO THE FORECAST AREA PRIOR TO DAYBREAK AHEAD OF THE
UPPER WAVE.
ALL OF THESE FEATURES REMAIN SUPPORTIVE OF THE RESUMPTION OF
WIDESPREAD SNOW AND EXPECTATION FOR ADDITIONAL ACCUMULATIONS INTO
THE EARLY AFTERNOON...ESPECIALLY ACROSS THE NORTHERN HALF OF THE
FORECAST AREA. WITH THAT BEING SAID...TEMPERATURES WITHIN THE
BOUNDARY LAYER NEED TO BE MONITORED OVER THE NEXT SEVERAL HOURS AS
IMPACTS TO PRECIP TYPE OVER SOUTHERN COUNTIES AND SNOWFALL RATIOS IN
GENERAL ARE POSSIBLE. LAPS SOUNDINGS INDICATING A VERY SHALLOW LAYER
OF AIR NEAR THE SURFACE THAT SITS JUST ABOVE FREEZING OVER THE
SOUTHERN HALF OF THE FORECAST AREA WITH TEMPS AT 32-35F. WITH THE
LOW LEVEL JET TRANSPORTING SLIGHTLY WARMER BOUNDARY LAYER AIR NORTH
OVER THE NEXT FEW HOURS...EXPECTING SURFACE TEMPS TO MOVE LITTLE AND
MAY EVEN RISE A FEW DEGREES AFTER DAYBREAK. OVERALL...LOW LEVEL
THERMALS OVER THE NEXT SEVERAL HOURS REMAIN SUGGESTIVE OF SNOW AS
RATES INTENSIFY WITH THE EXPANSION OF THE PRECIP SHIELD. AS SLIGHTLY
WARMER AIR NOSES INTO SOUTHERN COUNTIES WITH THE LOW LEVEL JET AFTER
DAYBREAK HOWEVER...POTENTIAL FOR SOME LIGHT RAIN TO MIX IN WITH THE
SNOW. RAP AND NAM ARE THE MOST AGGRESSIVE WITH BRINGING THE 0C LINE
AT 850MB ACROSS THE SOUTHEASTERN HALF OF THE FORECAST AREA THROUGH
18Z...BOTH HINTING AT A TROWAL ROTATING INTO OUR SOUTHEAST AND
EASTERN COUNTIES. CONSIDERING RECENT TRENDS AND THE FACT THAT
SURFACE TEMPS ARE RUNNING A FEW DEGREES WARMER THAN PREVIOUSLY
THOUGHT...WILL BRING CHANCE FOR RAIN TO MIX IN WITH SNOW TO A
VINCENNES-BEDFORD-GREENSBURG LINE BY MID MORNING CONTINUING INTO
EARLY AFTERNOON.
CONSIDERING ABOVE THOUGHTS AND TAKING INTO ACCOUNT LIQUID TO
SNOWFALL RATIOS LIKELY REMAINING NEAR 10-1 FOR MUCH OF THE FORECAST
AREA FOR THE DURATION OF THE EVENT...HAVE TRIMMED TOTAL SNOWFALL
AMOUNTS A BIT OVER ALL BUT FAR NORTHERN SECTIONS. TOTAL SNOW ACCUMS
INCLUDING WHAT FELL SINCE FRIDAY EVENING STILL EXPECTED TO AROUND
6-7 INCHES OVER FAR NORTHERN COUNTIES...DIMINISHING TO 4-5 ALONG THE
I-70 CORRIDOR. FURTHER SOUTH...EXPECTING TOTALS GENERALLY AT 1-3
INCHES. THE NORTHWARD EXTENT OF THE ABOVE FREEZING AIR WITHIN THE
BOUNDARY LAYER AND THE POSSIBILITY OF ENHANCED FORCING IN THE
VICINITY OF A TROWAL COULD LEAD TO FURTHER ADJUSTMENTS IN THESE
AMOUNTS AND WILL CONTINUE TO MONITOR. THE WARNING AND ADVISORY WILL
CONTINUE IN THEIR CURRENT STATES THROUGH 23Z.
TEMPS...NEARLY STEADY TEMPS EXPECTED TODAY BUT IN GENERAL STILL FEEL
MOS IS TOO WARM WITH HIGHS. LEANED CLOSER TO CONSALL WITH TEMPS
RANGING FROM THE LOWER 30S NORTH TO MID 30S SOUTH.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
ISSUED AT 356 AM EST SAT DEC 14 2013
FORECAST CHALLENGES FOCUS ON MINOR SNOW CHANCES AND TEMPERATURES AS
COLDER AIR RETURNS FOR MUCH OF THE SHORT TERM.
ANY LINGERING LIGHT SNOW ON THE BACK SIDE OF THE DEPARTING SYSTEM
WILL END DURING THE EVENING...POSSIBLY AS A BRIEF PERIOD OF DRIZZLE
OR FREEZING DRIZZLE AS DRIER AIR DEEPENS ABOVE THE BOUNDARY LAYER.
LOW CLOUDS WILL PERSIST ALL NIGHT AS MOISTURE REMAINS TRAPPED
BENEATH A SHARP INVERSION.
THE PASSAGE OF TWO DEEP UPPER LOWS TO THE NORTH OF THE GREAT LAKES
WILL MAINTAIN BROAD TROUGHING ALOFT AND A GENERAL NORTHWEST FLOW
THROUGHOUT THE PERIOD. SEVERAL DISTURBANCES ALOFT WILL TRAVERSE THE
REGION MAINTAINING MOSTLY CLOUDY CONDITIONS AND BRINGING PERIODIC
LIGHT SNOW SHOWERS AND FLURRIES ACROSS MUCH OF THE FORECAST AREA.
FLURRIES ARE POSSIBLE WITHIN A BROAD CYCLONIC FLOW SUNDAY AND SUNDAY
NIGHT. STRONGER UPPER WAVE SET TO TRACK ACROSS THE LOWER GREAT LAKES
MONDAY AND WILL CARRY CHANCES FOR SNOW SHOWERS THROUGHOUT THE DAY.
SOUTHERLY FLOW WILL DEVELOP ON THE BACK SIDE OF A SURFACE HIGH
PRESSURE RIDGE BY MONDAY ALLOWING FOR WARM ADVECTION TO DEVELOP WITH
MODERATING TEMPS.
TEMPS...PREFER THE COLDER MAVMOS THROUGH MUCH OF THE PERIOD AS IT
APPEARS TO CAPTURE THE INFLUENCE FROM THE LEFTOVER SNOWPACK FROM
STORM TODAY BETTER. HIGHS WILL FALL BACK INTO THE LOWER/MIDDLE 20S
ON SUNDAY WITH STRONG COLD ADVECTION. THE SHIFT TO SOUTHERLY FLOW
MONDAY WILL ALLOW FOR A RECOVERY INTO THE 30S OVER SOUTHERN
COUNTIES. LOWS IN THE TEENS TONIGHT AND SUNDAY NIGHT WILL RECOVER
INTO THE 20S MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
ISSUED AT 357 AM EST SAT DEC 14 2013
THE EXTENDED PERIOD WILL START OUT WITH WEAK SHORTWAVES ROTATING
AROUND AN UPPER LOW OVER ONTARIO. THIS WILL RESULT IN LIGHT SNOW
SHOWERS OVER NORTHERN INDIANA. HOWEVER...CHOSE TO LEAVE PRECIP OUT
OF CENTRAL INDIANA ON TUESDAY SINCE BEST LIFT WILL BE NORTH OF
FORECAST AREA. DRY CONDITIONS WILL PREVAIL THROUGH MID-WEEK WITH
DECENT SUBSIDENCE ALOFT. HOWEVER...THE RIDGING OVER THE CENTRAL
U.S. WILL START TO BREAK DOWN BY THURSDAY AS A LOW PRESSURE SYSTEM
STRENGTHENS OVER THE WESTERN UNITED STATES. MEANWHILE...WARM AIR
WILL BE ADVECTED INTO CENTRAL INDIANA AHEAD OF A SURFACE
LOW...RESULTING IN ABOVE NORMAL TEMPERATURES. PRECIP ASSOCIATED
WITH THAT SURFACE LOW WILL INITIALLY FALL IN THE FORM OF RAIN ON
THURSDAY NIGHT AND FRIDAY...AND THEN TRANSITION TO A RAIN/SNOW MIX
AS COLDER AIR FILTERS IN BEHIND THE ASSOCIATED COLD FRONT.
&&
.AVIATION /DISCUSSION FOR THE 14/12Z TAF ISSUANCE/...
ISSUED AT 609 AM EST SAT DEC 14 2013
LIFR CONDITIONS CAN BE EXPECTED WELL INTO THIS AFTERNOON AS BANDS
OF SNOW CONTINUE TO PASS OVER TAF SITES. SNOW SHOWERS WILL WEAKEN
AFTER SAT 21Z AND THEN COME TO AN END AROUND SUN 00Z. MINIMAL
IMPROVEMENTS IN VISIBILITIES CAN BE EXPECTED BY THIS EVENING...BUT
DO NOT EXPECT CEILINGS TO IMPROVE TO MVFR CATEGORY UNTIL AFTER SUN
06Z. WINDS WILL BECOME NORTHWESTERLY THIS AFTERNOON AND STRENGTHEN
SLIGHTLY DURING THE EVENING HOURS WITH SUSTAINED SPEEDS OF
8 TO 12 KTS.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR
INZ053>057-060>065-067>072.
WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR INZ021-
028>031-035>049-051-052.
&&
$$
SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....TDUD
AVIATION...TDUD
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
WWW.TWITTER.COM/NWSINDIANAPOLIS
WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
358 AM EST SAT DEC 14 2013
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 356 AM EST SAT DEC 14 2013
ACCUMULATING SNOW WILL CONTINUE ACROSS MUCH OF THE FORECAST AREA
TODAY AS LOW PRESSURE TRACKS THROUGH THE OHIO VALLEY. ARCTIC AIR
WILL RETURN TONIGHT AS THE STORM MOVES AWAY TO THE EAST...WITH
CHILLY TEMPERATURES INTO THE EARLY PART OF THE WEEK. HIGH PRESSURE
WILL BRING DRY WEATHER AND A WARMING TREND THROUGH MIDWEEK.
UNSETTLED WEATHER RETURNS LATE THURSDAY AND FRIDAY AS LOW PRESSURE
TRACKS THROUGH THE REGION...WITH TEMPERATURES WARM ENOUGH FOR
PRECIPITATION TO FALL AS RAIN ACROSS CENTRAL INDIANA.
&&
.NEAR TERM /TODAY/...
ISSUED AT 356 AM EST SAT DEC 14 2013
COMPLEX WINTER STORM ONGOING ACROSS THE REGION EARLY THIS MORNING.
STEADIER SNOWS CONTINUE TO FALL OVER NORTHERN COUNTIES WITH A DRY
SLOT FURTHER SOUTH LIMITING PRECIP TO VERY LIGHT SNOW OR SHUTTING IT
OFF COMPLETELY ACROSS MUCH OF THE REST OF THE FORECAST AREA. BROADER
AREA OF HEAVIER PRECIPITATION QUICKLY EXPANDING NORTHEAST OUT OF THE
LOWER OHIO VALLEY. TEMPS WERE IN THE LOWER AND MIDDLE 30S AS OF 08Z.
DRY SLOT IS TAKING ITS TIME TO FILL IN...BUT EXPECT AREA OF HEAVIER
PRECIPITATION WILL EXPAND INTO THE FORECAST AREA OVER THE NEXT
SEVERAL HOURS WITH SNOWFALL COMMENCING ONCE AGAIN IN LOCATIONS WHERE
IT HAS STOPPED. RAP/NAM BOTH INDICATING A 50KT LOW LEVEL JET RIDING
UP THE MISSISSIPPI VALLEY AND CONTRIBUTING TO THE EXPANSION OF
PRECIP OVER THE LOWER OHIO VALLEY. THE LOW LEVEL JET WILL SHIFT EAST
ACROSS THE REGION AHEAD OF THE 850MB LOW THROUGH
MIDDAY...MAINTAINING A PLENTIFUL SURGE OF LOW LEVEL MOISTURE INTO
THE REGION. MAIN UPPER LEVEL WAVE LOCATED OVER SOUTHWEST MISSOURI
EARLY THIS MORNING WILL LIFT NORTHEAST ACROSS THE FORECAST AREA BY
EARLY AFTERNOON. SHORT RANGE MODEL GUIDANCE CONTINUING TO ADVERTISE
A DEFORMATION AXIS AND FRONTOGENETICAL FORCING WITHIN THE MID LEVELS
EXPANDING INTO THE FORECAST AREA PRIOR TO DAYBREAK AHEAD OF THE
UPPER WAVE.
ALL OF THESE FEATURES REMAIN SUPPORTIVE OF THE RESUMPTION OF
WIDESPREAD SNOW AND EXPECTATION FOR ADDITIONAL ACCUMULATIONS INTO
THE EARLY AFTERNOON...ESPECIALLY ACROSS THE NORTHERN HALF OF THE
FORECAST AREA. WITH THAT BEING SAID...TEMPERATURES WITHIN THE
BOUNDARY LAYER NEED TO BE MONITORED OVER THE NEXT SEVERAL HOURS AS
IMPACTS TO PRECIP TYPE OVER SOUTHERN COUNTIES AND SNOWFALL RATIOS IN
GENERAL ARE POSSIBLE. LAPS SOUNDINGS INDICATING A VERY SHALLOW LAYER
OF AIR NEAR THE SURFACE THAT SITS JUST ABOVE FREEZING OVER THE
SOUTHERN HALF OF THE FORECAST AREA WITH TEMPS AT 32-35F. WITH THE
LOW LEVEL JET TRANSPORTING SLIGHTLY WARMER BOUNDARY LAYER AIR NORTH
OVER THE NEXT FEW HOURS...EXPECTING SURFACE TEMPS TO MOVE LITTLE AND
MAY EVEN RISE A FEW DEGREES AFTER DAYBREAK. OVERALL...LOW LEVEL
THERMALS OVER THE NEXT SEVERAL HOURS REMAIN SUGGESTIVE OF SNOW AS
RATES INTENSIFY WITH THE EXPANSION OF THE PRECIP SHIELD. AS SLIGHTLY
WARMER AIR NOSES INTO SOUTHERN COUNTIES WITH THE LOW LEVEL JET AFTER
DAYBREAK HOWEVER...POTENTIAL FOR SOME LIGHT RAIN TO MIX IN WITH THE
SNOW. RAP AND NAM ARE THE MOST AGGRESSIVE WITH BRINGING THE 0C LINE
AT 850MB ACROSS THE SOUTHEASTERN HALF OF THE FORECAST AREA THROUGH
18Z...BOTH HINTING AT A TROWAL ROTATING INTO OUR SOUTHEAST AND
EASTERN COUNTIES. CONSIDERING RECENT TRENDS AND THE FACT THAT
SURFACE TEMPS ARE RUNNING A FEW DEGREES WARMER THAN PREVIOUSLY
THOUGHT...WILL BRING CHANCE FOR RAIN TO MIX IN WITH SNOW TO A
VINCENNES-BEDFORD-GREENSBURG LINE BY MID MORNING CONTINUING INTO
EARLY AFTERNOON.
CONSIDERING ABOVE THOUGHTS AND TAKING INTO ACCOUNT LIQUID TO
SNOWFALL RATIOS LIKELY REMAINING NEAR 10-1 FOR MUCH OF THE FORECAST
AREA FOR THE DURATION OF THE EVENT...HAVE TRIMMED TOTAL SNOWFALL
AMOUNTS A BIT OVER ALL BUT FAR NORTHERN SECTIONS. TOTAL SNOW ACCUMS
INCLUDING WHAT FELL SINCE FRIDAY EVENING STILL EXPECTED TO AROUND
6-7 INCHES OVER FAR NORTHERN COUNTIES...DIMINISHING TO 4-5 ALONG THE
I-70 CORRIDOR. FURTHER SOUTH...EXPECTING TOTALS GENERALLY AT 1-3
INCHES. THE NORTHWARD EXTENT OF THE ABOVE FREEZING AIR WITHIN THE
BOUNDARY LAYER AND THE POSSIBILITY OF ENHANCED FORCING IN THE
VICINITY OF A TROWAL COULD LEAD TO FURTHER ADJUSTMENTS IN THESE
AMOUNTS AND WILL CONTINUE TO MONITOR. THE WARNING AND ADVISORY WILL
CONTINUE IN THEIR CURRENT STATES THROUGH 23Z.
TEMPS...NEARLY STEADY TEMPS EXPECTED TODAY BUT IN GENERAL STILL FEEL
MOS IS TOO WARM WITH HIGHS. LEANED CLOSER TO CONSALL WITH TEMPS
RANGING FROM THE LOWER 30S NORTH TO MID 30S SOUTH.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
ISSUED AT 356 AM EST SAT DEC 14 2013
FORECAST CHALLENGES FOCUS ON MINOR SNOW CHANCES AND TEMPERATURES AS
COLDER AIR RETURNS FOR MUCH OF THE SHORT TERM.
ANY LINGERING LIGHT SNOW ON THE BACK SIDE OF THE DEPARTING SYSTEM
WILL END DURING THE EVENING...POSSIBLY AS A BRIEF PERIOD OF DRIZZLE
OR FREEZING DRIZZLE AS DRIER AIR DEEPENS ABOVE THE BOUNDARY LAYER.
LOW CLOUDS WILL PERSIST ALL NIGHT AS MOISTURE REMAINS TRAPPED
BENEATH A SHARP INVERSION.
THE PASSAGE OF TWO DEEP UPPER LOWS TO THE NORTH OF THE GREAT LAKES
WILL MAINTAIN BROAD TROUGHING ALOFT AND A GENERAL NORTHWEST FLOW
THROUGHOUT THE PERIOD. SEVERAL DISTURBANCES ALOFT WILL TRAVERSE THE
REGION MAINTAINING MOSTLY CLOUDY CONDITIONS AND BRINGING PERIODIC
LIGHT SNOW SHOWERS AND FLURRIES ACROSS MUCH OF THE FORECAST AREA.
FLURRIES ARE POSSIBLE WITHIN A BROAD CYCLONIC FLOW SUNDAY AND SUNDAY
NIGHT. STRONGER UPPER WAVE SET TO TRACK ACROSS THE LOWER GREAT LAKES
MONDAY AND WILL CARRY CHANCES FOR SNOW SHOWERS THROUGHOUT THE DAY.
SOUTHERLY FLOW WILL DEVELOP ON THE BACK SIDE OF A SURFACE HIGH
PRESSURE RIDGE BY MONDAY ALLOWING FOR WARM ADVECTION TO DEVELOP WITH
MODERATING TEMPS.
TEMPS...PREFER THE COLDER MAVMOS THROUGH MUCH OF THE PERIOD AS IT
APPEARS TO CAPTURE THE INFLUENCE FROM THE LEFTOVER SNOWPACK FROM
STORM TODAY BETTER. HIGHS WILL FALL BACK INTO THE LOWER/MIDDLE 20S
ON SUNDAY WITH STRONG COLD ADVECTION. THE SHIFT TO SOUTHERLY FLOW
MONDAY WILL ALLOW FOR A RECOVERY INTO THE 30S OVER SOUTHERN
COUNTIES. LOWS IN THE TEENS TONIGHT AND SUNDAY NIGHT WILL RECOVER
INTO THE 20S MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
ISSUED AT 357 AM EST SAT DEC 14 2013
THE EXTENDED PERIOD WILL START OUT WITH WEAKS SHORTWAVES ROTATING
AROUND AN UPPER LOW OVER ONTARIO. THIS WILL RESULT IN LIGHT SNOW
SHOWERS OVER NORTHERN INDIANA. HOWEVER...CHOSE TO LEAVE PRECIP OUT
OF CENTRAL INDIANA ON TUESDAY SINCE BEST LIFT WILL BE NORTH OF
FORECAST AREA. DRY CONDITIONS WILL PREVAIL THROUGH MID-WEEK WITH
DECENT SUBSIDENCE ALOFT. HOWEVER...THE RIDGING OVER THE CENTRAL
U.S. WILL START TO BREAK DOWN BY THURSDAY AS A LOW PRESSURE SYSTEM
STRENGTHENS OVER THE WESTERN UNITED STATES. MEANWHILE...WARM AIR
WILL BE ADVECTED INTO CENTRAL INDIANA AHEAD OF A SURFACE
LOW...RESULTING IN ABOVE NORMAL TEMPERATURES. PRECIP ASSOCIATED
WITH THAT SURFACE LOW WILL INITIALLY FALL IN THE FORM OF RAIN ON
THURSDAY NIGHT AND FRIDAY...AND THEN TRANSITION TO A RAIN/SNOW MIX
AS COLDER AIR FILTERS IN BEHIND THE ASSOCIATED COLD FRONT.
&&
.AVIATION /DISCUSSION FOR THE 14/09Z TAF UPDATE/...
ISSUED AT 330 AM EST SAT DEC 14 2013
UPDATE...
NO MAJOR CHANGES. CONDITIONS CONTINUE TO FLUCTUATE BETWEEN MVFR
AND IFR CATEGORIES. MADE MINOR ADJUSTMENTS TO REFLECT CURRENT
OBSERVATIONS.
PREVIOUS DISCUSSION...
FLUCTUATING MVFR TO IFR THROUGH MUCH OF THE NIGHT...WITH CONDITIONS
WORSENING AGAIN BY DAYBREAK AND REMAINING IFR MUCH OF THE DAY.
SNOW HAS BECOME MORE SHOWERY IN THE WAKE OF THE FIRST WAVE...BUT
EXPECT THE NEXT WAVE TO INCREASE BY DAYBREAK. MAY SEE SOME LIFR AT
TIMES DURING THE MORNING TO MIDDAY HOURS.
WINDS WILL BE BELOW 10KT THROUGH THE PERIOD...LIMITING BLOWING OF
SNOW. WINDS WILL BE EASTERLY AND THEN BECOME NORTHERLY LATE IN THE
PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR
INZ053>057-060>065-067>072.
WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR INZ021-
028>031-035>049-051-052.
&&
$$
SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....TDUD
AVIATION...NIELD/TDUD
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
WWW.TWITTER.COM/NWSINDIANAPOLIS
WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
356 AM EST SAT DEC 14 2013
.UPDATE...
THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 356 AM EST SAT DEC 14 2013
ACCUMULATING SNOW WILL CONTINUE ACROSS MUCH OF THE FORECAST AREA
TODAY AS LOW PRESSURE TRACKS THROUGH THE OHIO VALLEY. ARCTIC AIR
WILL RETURN TONIGHT AS THE STORM MOVES AWAY TO THE EAST...WITH
CHILLY TEMPERATURES INTO THE EARLY PART OF THE WEEK. HIGH PRESSURE
WILL BRING DRY WEATHER AND A WARMING TREND THROUGH MIDWEEK.
UNSETTLED WEATHER RETURNS LATE THURSDAY AND FRIDAY AS LOW PRESSURE
TRACKS THROUGH THE REGION...WITH TEMPERATURES WARM ENOUGH FOR
PRECIPITATION TO FALL AS RAIN ACROSS CENTRAL INDIANA.
&&
.NEAR TERM /TODAY/...
ISSUED AT 356 AM EST SAT DEC 14 2013
COMPLEX WINTER STORM ONGOING ACROSS THE REGION EARLY THIS MORNING.
STEADIER SNOWS CONTINUE TO FALL OVER NORTHERN COUNTIES WITH A DRY
SLOT FURTHER SOUTH LIMITING PRECIP TO VERY LIGHT SNOW OR SHUTTING IT
OFF COMPLETELY ACROSS MUCH OF THE REST OF THE FORECAST AREA. BROADER
AREA OF HEAVIER PRECIPITATION QUICKLY EXPANDING NORTHEAST OUT OF THE
LOWER OHIO VALLEY. TEMPS WERE IN THE LOWER AND MIDDLE 30S AS OF 08Z.
DRY SLOT IS TAKING ITS TIME TO FILL IN...BUT EXPECT AREA OF HEAVIER
PRECIPITATION WILL EXPAND INTO THE FORECAST AREA OVER THE NEXT
SEVERAL HOURS WITH SNOWFALL COMMENCING ONCE AGAIN IN LOCATIONS WHERE
IT HAS STOPPED. RAP/NAM BOTH INDICATING A 50KT LOW LEVEL JET RIDING
UP THE MISSISSIPPI VALLEY AND CONTRIBUTING TO THE EXPANSION OF
PRECIP OVER THE LOWER OHIO VALLEY. THE LOW LEVEL JET WILL SHIFT EAST
ACROSS THE REGION AHEAD OF THE 850MB LOW THROUGH
MIDDAY...MAINTAINING A PLENTIFUL SURGE OF LOW LEVEL MOISTURE INTO
THE REGION. MAIN UPPER LEVEL WAVE LOCATED OVER SOUTHWEST MISSOURI
EARLY THIS MORNING WILL LIFT NORTHEAST ACROSS THE FORECAST AREA BY
EARLY AFTERNOON. SHORT RANGE MODEL GUIDANCE CONTINUING TO ADVERTISE
A DEFORMATION AXIS AND FRONTOGENETICAL FORCING WITHIN THE MID LEVELS
EXPANDING INTO THE FORECAST AREA PRIOR TO DAYBREAK AHEAD OF THE
UPPER WAVE.
ALL OF THESE FEATURES REMAIN SUPPORTIVE OF THE RESUMPTION OF
WIDESPREAD SNOW AND EXPECTATION FOR ADDITIONAL ACCUMULATIONS INTO
THE EARLY AFTERNOON...ESPECIALLY ACROSS THE NORTHERN HALF OF THE
FORECAST AREA. WITH THAT BEING SAID...TEMPERATURES WITHIN THE
BOUNDARY LAYER NEED TO BE MONITORED OVER THE NEXT SEVERAL HOURS AS
IMPACTS TO PRECIP TYPE OVER SOUTHERN COUNTIES AND SNOWFALL RATIOS IN
GENERAL ARE POSSIBLE. LAPS SOUNDINGS INDICATING A VERY SHALLOW LAYER
OF AIR NEAR THE SURFACE THAT SITS JUST ABOVE FREEZING OVER THE
SOUTHERN HALF OF THE FORECAST AREA WITH TEMPS AT 32-35F. WITH THE
LOW LEVEL JET TRANSPORTING SLIGHTLY WARMER BOUNDARY LAYER AIR NORTH
OVER THE NEXT FEW HOURS...EXPECTING SURFACE TEMPS TO MOVE LITTLE AND
MAY EVEN RISE A FEW DEGREES AFTER DAYBREAK. OVERALL...LOW LEVEL
THERMALS OVER THE NEXT SEVERAL HOURS REMAIN SUGGESTIVE OF SNOW AS
RATES INTENSIFY WITH THE EXPANSION OF THE PRECIP SHIELD. AS SLIGHTLY
WARMER AIR NOSES INTO SOUTHERN COUNTIES WITH THE LOW LEVEL JET AFTER
DAYBREAK HOWEVER...POTENTIAL FOR SOME LIGHT RAIN TO MIX IN WITH THE
SNOW. RAP AND NAM ARE THE MOST AGGRESSIVE WITH BRINGING THE 0C LINE
AT 850MB ACROSS THE SOUTHEASTERN HALF OF THE FORECAST AREA THROUGH
18Z...BOTH HINTING AT A TROWAL ROTATING INTO OUR SOUTHEAST AND
EASTERN COUNTIES. CONSIDERING RECENT TRENDS AND THE FACT THAT
SURFACE TEMPS ARE RUNNING A FEW DEGREES WARMER THAN PREVIOUSLY
THOUGHT...WILL BRING CHANCE FOR RAIN TO MIX IN WITH SNOW TO A
VINCENNES-BEDFORD-GREENSBURG LINE BY MID MORNING CONTINUING INTO
EARLY AFTERNOON.
CONSIDERING ABOVE THOUGHTS AND TAKING INTO ACCOUNT LIQUID TO
SNOWFALL RATIOS LIKELY REMAINING NEAR 10-1 FOR MUCH OF THE FORECAST
AREA FOR THE DURATION OF THE EVENT...HAVE TRIMMED TOTAL SNOWFALL
AMOUNTS A BIT OVER ALL BUT FAR NORTHERN SECTIONS. TOTAL SNOW ACCUMS
INCLUDING WHAT FELL SINCE FRIDAY EVENING STILL EXPECTED TO AROUND
6-7 INCHES OVER FAR NORTHERN COUNTIES...DIMINISHING TO 4-5 ALONG THE
I-70 CORRIDOR. FURTHER SOUTH...EXPECTING TOTALS GENERALLY AT 1-3
INCHES. THE NORTHWARD EXTENT OF THE ABOVE FREEZING AIR WITHIN THE
BOUNDARY LAYER AND THE POSSIBILITY OF ENHANCED FORCING IN THE
VICINITY OF A TROWAL COULD LEAD TO FURTHER ADJUSTMENTS IN THESE
AMOUNTS AND WILL CONTINUE TO MONITOR. THE WARNING AND ADVISORY WILL
CONTINUE IN THEIR CURRENT STATES THROUGH 23Z.
TEMPS...NEARLY STEADY TEMPS EXPECTED TODAY BUT IN GENERAL STILL FEEL
MOS IS TOO WARM WITH HIGHS. LEANED CLOSER TO CONSALL WITH TEMPS
RANGING FROM THE LOWER 30S NORTH TO MID 30S SOUTH.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
ISSUED AT 356 AM EST SAT DEC 14 2013
FORECAST CHALLENGES FOCUS ON MINOR SNOW CHANCES AND TEMPERATURES AS
COLDER AIR RETURNS FOR MUCH OF THE SHORT TERM.
ANY LINGERING LIGHT SNOW ON THE BACK SIDE OF THE DEPARTING SYSTEM
WILL END DURING THE EVENING...POSSIBLY AS A BRIEF PERIOD OF DRIZZLE
OR FREEZING DRIZZLE AS DRIER AIR DEEPENS ABOVE THE BOUNDARY LAYER.
LOW CLOUDS WILL PERSIST ALL NIGHT AS MOISTURE REMAINS TRAPPED
BENEATH A SHARP INVERSION.
THE PASSAGE OF TWO DEEP UPPER LOWS TO THE NORTH OF THE GREAT LAKES
WILL MAINTAIN BROAD TROUGHING ALOFT AND A GENERAL NORTHWEST FLOW
THROUGHOUT THE PERIOD. SEVERAL DISTURBANCES ALOFT WILL TRAVERSE THE
REGION MAINTAINING MOSTLY CLOUDY CONDITIONS AND BRINGING PERIODIC
LIGHT SNOW SHOWERS AND FLURRIES ACROSS MUCH OF THE FORECAST AREA.
FLURRIES ARE POSSIBLE WITHIN A BROAD CYCLONIC FLOW SUNDAY AND SUNDAY
NIGHT. STRONGER UPPER WAVE SET TO TRACK ACROSS THE LOWER GREAT LAKES
MONDAY AND WILL CARRY CHANCES FOR SNOW SHOWERS THROUGHOUT THE DAY.
SOUTHERLY FLOW WILL DEVELOP ON THE BACK SIDE OF A SURFACE HIGH
PRESSURE RIDGE BY MONDAY ALLOWING FOR WARM ADVECTION TO DEVELOP WITH
MODERATING TEMPS.
TEMPS...PREFER THE COLDER MAVMOS THROUGH MUCH OF THE PERIOD AS IT
APPEARS TO CAPTURE THE INFLUENCE FROM THE LEFTOVER SNOWPACK FROM
STORM TODAY BETTER. HIGHS WILL FALL BACK INTO THE LOWER/MIDDLE 20S
ON SUNDAY WITH STRONG COLD ADVECTION. THE SHIFT TO SOUTHERLY FLOW
MONDAY WILL ALLOW FOR A RECOVERY INTO THE 30S OVER SOUTHERN
COUNTIES. LOWS IN THE TEENS TONIGHT AND SUNDAY NIGHT WILL RECOVER
INTO THE 20S MONDAY NIGHT.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ISSUED AT 211 PM EST FRI DEC 13 2013
TRANQUIL WEATHER MOST OF THIS TIME FRAME WITH WARM UP COMING LATE
WEEK ALONG WITH RAIN. MODELS IN DECENT ENOUGH AGREEMENT FOR MOST
PERIODS AND HAVE USED A BLEND. IN LARGER PICTURE BROAD EASTERN
NORTH AMERICA TROUGH GRADUALLY SHIFTS OFF THE COAST AS FLOW ZONES
OUT THEN TURNS SOUTHWESTERLY FOR US AS UPPER TROUGH DIGS INTO THE
WESTERN US AND THUS THE TRANSITION FROM COLD TO MILD.
THIS PERIOD WILL START OUT WITH A DECENT SNOWPACK THAT WILL HAVE
AN IMPACT ON KEEPING TEMPS A BIT COOLER THAN THEY WOULD OTHERWISE
BE FOR MUCH OF THE WEEK. LATE WEEK STRONG STORM SYSTEM BRINGS
SUBSTANTIALLY WARMER TEMPS BEGINNING THURSDAY AND ATTENDANT
PRECIPITATION SHOULD BE AS RAIN RELATIVE TO RECENT SNOWY PERIOD.
TEENS AND LOWER 20S MIN TEMPS WILL BE REPLACED BY ABOVE FREEZING
MINS BY FRIDAY MORNING. MAX TEMPS IN 30S VS 20S WILL FEEL
RELATIVELY MILD EARLY WEEK BUT WILL WARM TO UPPER 30S AND 40S
THURSDAY AND THEN UPPER 40S AND 50S FRIDAY SO A LATE WEEK SNOWMELT
COMBINED WITH RAINS COULD BRING SOME RIVER ISSUES.
&&
.AVIATION /DISCUSSION FOR THE 14/09Z TAF UPDATE/...
ISSUED AT 330 AM EST SAT DEC 14 2013
UPDATE...
NO MAJOR CHANGES. CONDITIONS CONTINUE TO FLUCTUATE BETWEEN MVFR
AND IFR CATEGORIES. MADE MINOR ADJUSTMENTS TO REFLECT CURRENT
OBSERVATIONS.
PREVIOUS DISCUSSION...
FLUCTUATING MVFR TO IFR THROUGH MUCH OF THE NIGHT...WITH CONDITIONS
WORSENING AGAIN BY DAYBREAK AND REMAINING IFR MUCH OF THE DAY.
SNOW HAS BECOME MORE SHOWERY IN THE WAKE OF THE FIRST WAVE...BUT
EXPECT THE NEXT WAVE TO INCREASE BY DAYBREAK. MAY SEE SOME LIFR AT
TIMES DURING THE MORNING TO MIDDAY HOURS.
WINDS WILL BE BELOW 10KT THROUGH THE PERIOD...LIMITING BLOWING OF
SNOW. WINDS WILL BE EASTERLY AND THEN BECOME NORTHERLY LATE IN THE
PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR
INZ053>057-060>065-067>072.
WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR INZ021-
028>031-035>049-051-052.
&&
$$
SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....TUCEK
AVIATION...NIELD/TDUD
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
WWW.TWITTER.COM/NWSINDIANAPOLIS
WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1151 PM EST Fri Dec 13 2013
...Updated Aviation Discussion...
...Forecast Update...
Issued at 955 PM EST Fri Dec 13 2013
That first wave of light to moderate precip (though the flakes at
times were large) that came through has helped to raise dewpoints
quite a bit, and they have stayed that way a couple of hours now
with upstream locations not dropping too much. Forecast soundings
from the models look like they are overdoing the dry air that was
supposed to follow that wave, though the RUC does keep higher
dewpoint air over us now. Given these changes, think the rain/snow
transition line can be moved north. Have adjusted the forecast as
such and now have snow totals of 1-2 inches only over my northern
stripe of counties as well as the northern parts of Perry and
Crawford. Thus have cancelled the advisory south of this line. Will
keep in a special weather statement for a mix of precip south of
that advisory.
Issued at 600 PM EST Fri Dec 13 2013
Seeing a NW/SE-oriented band of precipitation well out ahead of the
main rainmake for tonight. Several of the high-res models have
picked up on this band and then bring a quiet weather period behind
it for a few hours. Have adjusted our pop grids to match this trend
and to account for the earlier onset. Have had several PING reports
of snow coming out of that band and the ob at KOWB indicated a
rain/snow mix. Soundings indicate the dry air in the low levels is
helping to bring temperatures down quickly as this precipitation
falls into it. Temps over our area now are around 40, but within the
band over PAH`s area they have fallen to 34. Updated forecast will
be out shortly.
.SHORT TERM (Now through Saturday Night)...
Issued at 305 PM EST Fri Dec 13 2013
...A ROUND OF WINTERY WEATHER TONIGHT WITH LIGHT SNOW ACCUMULATIONS
ACROSS SOUTHERN INDIANA...
In the near term, mid-high level cloud cover is quickly
overspreading the region. Skies were partly to mostly cloudy and
with a southerly wind flow, temperatures have warmed into the 40s
across Kentucky with middle to upper 30s across southern Indiana.
We expect cloudy skies to persist for the rest of the afternoon and
into the early evening with temperatures falling back into the lower
30s across southern Indiana and into the middle-upper 30s in KY.
Latest model data continues to have pretty good continuity from
previous data sets. The models all indicate that an area of low
pressure over eastern TX will continue to deepen and head
northeastward through the heart of the Ohio Valley during the short
term forecast period. A large batch of precipitation will accompany
this feature and begin to overspread the region tonight. With
surface temperatures dropping to near the freezing mark, this will
bring a mixed bag of wintry weather to the area tonight...followed
by a cold rain for Saturday and then a transition back to snow
Saturday night as colder air moves into the region.
As precipitation moves eastward toward the region this evening, it
will encounter a relatively dry airmass that is in place. This can
easily be seen in the 12Z BNA and ILN sounding data. Precipitation
aloft will move into the region and begin to saturate the column
from top to bottom. Given the scope of isentropic lift and synoptic
scale ascent ahead of this system, it appears that it will take an
hour or two for the column to saturate down. With this top to
bottom saturation, we will see evaporative cooling effects in which
the lower atmosphere...while initially warm will cool to an extent
this evening. Thus, the initial precipitation developing across the
region looks to be in the form of rain with some sleet at the
onset. A mix of rain/sleet/snow is likely in areas north of the
river at onset due to a cooler atmospheric profile that is expected
to be in place.
As the evening wears on, we will see the rain/sleet mixture change
over to mainly a snow/sleet mixture across the northern half of
Kentucky and all of southern Indiana. Thermal profiles across
southern Kentucky suggest that rain will likely be the main
precipitation type...especially in areas south of a line from
Hartford to around Richmond, KY. As we head into the overnight
hours, we expect a snow/sleet mixture to continue across northern KY
with mainly snow and some sleet across southern Indiana.
Temperatures north of the BG/WK parkways look to cool into the lower
30s. Probably will see temperatures cool to around 32-34, but in
heavier bursts of precipitation that fall as snow, temperatures in
localized areas could drop to 29-30. As we head toward sunrise, all
of the available guidance suggests that low-level warm air advection
will push further northward into KY changing the sleet/snow mixture
over to plain rain. Only areas that look to remain snow by sunrise
would be along and north of the I-64 corridor into southern Indiana.
Low-level warm air advection is expected to continue into the day on
Saturday with most areas going over to cold rain during the day.
This low-level warm nose looks to push northward into southern
Indiana resulting in an eventual change over to mostly rain even
that far north. Precipitation will pull on off to the northeast as
the low-pressure system heads into New England. As this occurs,
colder air will be pulled back down into the region Saturday night.
This will result in any left over precipitation changing over to
light snow. However...model soundings do show a loss of substantial
moisture in the dendritic ice crystal layer so we could see more of
light freezing drizzle falling across much of the region Saturday
night despite having a large cold low-level airmass in place.
As mentioned above, temperatures tonight are expected to fall to
around 30 in areas north of the Ohio River. Areas south of the Ohio
River and north of the WK/BG Pkys should cool into the 32-34 degree
range. Areas south of the Parkways look to cool into the 34-36
degree range. Highs on Saturday look to warm into the 40s across KY
with middle 30s in southern Indiana. Lows Saturday night will drop
back into the 20s in all areas.
With regards to snowfall amounts, we continue to believe the area at
most risk for snowfall accumulation overnight will be in areas of
southern Indiana north of the I-64 corridor. Along the I-64
corridor we expect around an inch or two of snow accumulation. In
our northern row of counties (along/north of a Jasper to Deputy
line) two to three inches of snowfall will be possible. For this
reason, we will continue the Winter Weather Advisory for tonight and
into Saturday morning.
In areas south of the Ohio River...but north of the WK/BG Pkys,
snowfall accumulation will be substantially less due to the expected
wintry mixture and warmer surface temperatures. Generally think
that a coating to maybe a half inch will be possible along and north
of the BG/WK Parkways with a half to 1 inch possible up near the
I-64 corridor to near the Ohio River. In general, expect most
snowfall accumulations in this area will be mainly on grassy and
elevated surfaces, but some accumulation on roads will be possible
during heavier precipitation periods. Very little snow accumulation
is expected across south-central Kentucky as precipitation will
remain in the form of a cold rain.
Some minor snow accumulations are possible late Saturday night if
the colder air gets into the region more quickly than forecast and
if precipitation is slower to move out. The combination of wet
roads and falling temperatures made lead to slick spots developing
late Saturday night. We plan on addressing those concerns in the
Hazardous Weather Outlook product.
.LONG TERM (Sunday through Friday)...
Issued at 305 PM EST Fri Dec 13 2013
A dry northwesterly flow at 500mb will develop late Sunday in the
wake of Saturday`s system, which is forecast to deepen off the New
England Coast early Monday. With a broad cyclonic flow centered over
the Great Lakes, a couple of weak upper disturbances will rotate
through the northern Ohio Valley over the first several days of next
week. However any light snow or snow showers will likely stay
confined to northern Indiana and Ohio. The first feature may bring
light flurries late Monday as for south as southern Indiana. Our
second feature seems timed for late Tuesday, with only some variable
cloudiness associated with this feature.
Temperatures will tend to moderate through the week, but slowly at
first as warmer air across the southern plains will stay shunted to
our southwest by the Great Lakes longwave trough. High temperatures
Tuesday will rise around 5 to 8 degrees above Monday`s expected
highs in the Lower 40s. A weak frontal passage will cool down
Wednesday just a bit as high pressure builds overhead.
Monday and Tuesday will feature variably cloudy skies, as the
combination of residual low level moisture and upper level waves
will likely bring a few cloudy periods. Mostly clear skies
anticipated for Wednesday.
Mild temperatures will finally return for Thursday and Friday, and
possibly Saturday as well. A digging jet streak along the west coast
late Wednesday will act to amplify a trough over the Rockies by late
Thursday, in turn leading to cyclogenesis across the plains. Robust
southwesterly flow will develop across the Lower Ohio Valley by
Thursday, continuing Friday. Initially, on Thursday, recycled
continental air will lead to mostly clear skies. Eventually, Gulf
moisture will return by Friday into early Saturday, bringing very
mild temperatures and a potential for quite a bit of rain early next
weekend. Highs Thursday and especially Friday will reach the 50s.
&&
.AVIATION (06Z TAF Update)...
Updated at 1150 PM EST Fri Dec 13 2013
Precipitation continues to push back in across the area tonight. It
still looks like SDF and LEX may see a mix of rain and snow off an
on through the night. This should change to all rain by around
sunrise as warmer air pushes in. BWG is expected to stay all rain as
it will remain warmer there. Rain will continue through the day
before tapering off during the late afternoon to evening hours.
There may be a chance for some flurries or freezing drizzle tomorrow
night. However, confidence in this remains low, so will keep the
forecast dry for now.
As the atmosphere saturates tonight, ceilings will lower to MVFR and
then IFR during the early morning hours. Visibilities will likely
bounce around, but generally hold in the MVFR range. Low level
moisture will linger into Saturday night, so ceilings are not
expected to improve through this TAF period. Winds will become
variable today as the low pressure moves northeast along the Ohio
River. They will then shift to westerly/northwesterly this afternoon
and evening as the low moves east.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...WINTER WEATHER ADVISORY until 10 AM EST /9 AM CST/ Saturday FOR
INZ076>079-083-084-089.
&&
$$
Update.........RJS
Short Term.....MJ
Long Term......JSD
Aviation.......EER
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
507 PM EST SAT DEC 14 2013
.SYNOPSIS...
LOW PRESSURE OVER THE MID OHIO VALLEY WILL TRACK ACROSS
PEENSYLVANIA TONIGHT...WITH A SECONDARY LOW DEVELOPING OVER THE DELMARVA
THIS EVENING. THE COASTAL LOW WILL INTENSIFY AS IT MOVES TOWARD
SOUTHERN NEW ENGLAND SUNDAY. AN UPPER TROUGH OF LOW PRESSURE WILL
PERSIST OVER THE MID-ATLANTIC INTO WEDNESDAY.
&&
.NEAR TERM /TONIGHT/...
ADVISORIES AND WRNGS RMN IN EFFECT. NEW PNS HAS BEEN SENT. TOP
SNOWFALL IS ARND 4" AT THE HIGHER WRN ELEVS. SNOW/IP BURST CAME
THRU IAD AT 407 PM AND HAS NOW MOVED UP TO BWI/BALT CITY IN THE
FORM OF RASN. TEMPS IN THE CENTRAL SHEN VLLY IN THE M30S...AND LWX
AND RNK RDR BOTH SHOW RDR REFLECTIVITY BEING SPOTTY FM ROA TO CHO.
FURTHER HRRR SHOWS THE BACK EDGE OF THE PCPN MOVG E OF THE MTNS BY
00Z. WHAT THIS ALL MEANS IS THAT IT IS LKLY THAT SOME OF THE
ADVSRY WL BE DROPPED DURG THE EVE HRS...PSBLY WRNG AS WELL.
LGT RAIN IN THE BALT-WASH METRO AND SOUTH THROUGH THE EVENING.
ALL PRECIP TAPERS OFF THROUGH THE LATE EVENING ACROSS THE
AREA...HOLDING ON THROUGH MIDNIGHT FOR NERN ZONES. MIN TEMPS
GENERALLY LOW TO MID 30S. AREAS WITH SNOW ON THE GROUND SHOULD SEE
SOME ADVECTION FOG TONIGHT.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
SUNDAY...POST FRONTAL WLY FLOW BREAKS MORNING FOG/LOW CLOUDS THROUGH
THE MIDDLE MORNING. GUSTS UP TO 30 MPH POSSIBLE BY LATE MORNING.
DOWNSLOPING FLOW ALLOWS FOR MAX TEMPS IN THE UPR 30S TO LOW
40S...MID 30S FOR UP ALONG MASON-DIXON WHERE THE SNOW PACK PERSISTS
AND MID 40S FOR N-CNTRL VA WHERE GREATER DOWNSLOPING OCCURS.
UPSLOPE SNOW THROUGH THE DAY WEST OF THE ALLEGHENY FRONT WITH A
COUPLE INCHES EXPECTED. LATER SHIFTS WILL NEED TO ASSESS WHETHER TO
EXTEND WINTER HEADLINES OR IF IT WILL BE SUB-ADVISORY (3" REQUIRED
FOR ADVISORY).
HIGH PRESSURE WILL BUILD OVER THE MIDDLE ATLANTIC REGION SUNDAY
NIGHT...AND CONTINUE INTO EARLY TUESDAY. GOOD CAA SUN NGT...BUT
DIMINISHES MON. THOSE WL BE THE BREEZY PDS. MON AFTN-NGT SHOULD BE
CALM...AND COLD.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
EXPECTING TEMPS BELOW NORMAL FOR TUESDAY AND WEDNESDAY AS GREAT
LAKES UPPER TROUGH PASSES TO OUR NORTH. VORT MAX AROUND THE BASE
OF THE TROUGH ALONG WITH SOME LIMITED MOISTURE AND COLD FROPA
LOOKS TO BRING SOME UPSLOPE SNOW SHOWERS TO THE ALLEGHENY FRONT
TUESDAY INTO TUESDAY NIGHT. HIGH PRESSURE AND UPPER RIDGING BUILDS
ACROSS THE AREA FOR THURSDAY. A WARMING TREND INTO THE WEEKEND IS
EXPECTED AHEAD OF LONG WAVE TROUGH. SOUTHERN STREAM LOW EJECTING
INTO THE GREAT LAKES REGION FOR NEXT WEEKEND INTO EARLY NEXT WEEK
STILL HAS BIG TIMING AND PLACEMENT INCONSISTENCIES IN LONG TERM
MODELS.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
IFR IN SNOW ONLY REST OF THE AFTERNOON. ACCUMULATING SNOW ONLY IN
KMRB...MAYBE SOME SLUSH AT KBWI...OTW RAIN OR MELTING SNOW AT THE
OTHER TERMINALS. CIGS DROP AND RAIN INCREASES...WITH IFR EXPECTED
ACROSS THE TERMINALS THIS EVENING IN THE EARLY MORNING HOURS. COLD
FRONT CROSSES LATE TONIGHT...BUT IFR CIGS MAY NOT BREAK UNTIL
SUNRISE SUNDAY.
MOSTLY VFR CONDITIONS EXPECTED SUNDAY THROUGH THURSDAY. GUSTY WEST
TO NORTHWEST WINDS EXPECTED SUNDAY AND SUNDAY NIGHT.
&&
.MARINE...
SCA UP FOR ALL WATERS...THOUGH THE ELY FLOW LOOKS TO BE WEAK ON THE
TIDAL POTOMAC...WITH 20 KT GUSTS EXPECTED ON THE MD PORTION OF THE
BAY. THE CENTER OF THE COASTAL LOW WILL TRACK NEAR OR OVER THE MD
PART OF THE BAY...SO THERE WILL PROBABLY BE A LULL IN WINDS UNTIL
MORNING. WLY FLOW GUSTS 20 TO 25 KT ACROSS THE WATERS THROUGH SUNDAY.
BEST MIXING WILL SLIDE EAST OF THE WATERS SUNDAY NIGHT. HV SCA/S
ENDING IN THE PTMC AND WRN INLETS...BUT NOT THE BAY ITSELF OR ERN
INLETS. HIGH PRESSURE BUILDS LATER MON INTO TUE. THAT AFFORDS
ANOTHER OPPORTUNITY FOR DAYTIME MIXING TO REINVIGORATE WNDS MONDAY
MRNG.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER STORM WARNING UNTIL 1 AM EST SUNDAY FOR MDZ003-501-502.
WINTER WEATHER ADVISORY UNTIL 1 AM EST SUNDAY FOR MDZ004>007.
VA...WINTER WEATHER ADVISORY UNTIL 1 AM EST SUNDAY FOR VAZ025>031-
036>040-042-501-503-504.
WV...WINTER STORM WARNING UNTIL 1 AM EST SUNDAY FOR WVZ050>052-
501>504.
WINTER WEATHER ADVISORY UNTIL 1 AM EST SUNDAY FOR WVZ053-055-
505-506.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR ANZ530>534-
539>541-543.
SMALL CRAFT ADVISORY UNTIL 6 PM EST SUNDAY FOR ANZ535-542.
SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST SUNDAY NIGHT FOR
ANZ536>538.
&&
$$
UPDATE...WOODY!
PRVS...HTS/BAJ/AEB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
134 PM EST SAT DEC 14 2013
.UPDATE...
ISSUED AT 133 PM EST SAT DEC 14 2013
NO CHANGES EXPECT AT THIS TIME TO THE LAKE EFFECT SNOW ADVISORIES
FOR MENOMINEE AND DELTA COUNTIES. AS NOTED IN THE PREVIOUS
DISCUSSION...DOMINANT BANDS HAVE BEEN DIFFICULT TO FORM GIVEN THE
VARYING WINDS AT AND JUST ABOVE THE SFC. DID HAVE REPORT EARLIER
TODAY OF AROUND 1IN OR SNOW IN A LITTLE OVER AN HR OVER FAR SW
SCHOOLCRAFT CO. HAVE ALSO HAD A REPORT OF AROUND 2IN ELSEWHERE IN
THE ADVISORY AREA. RADAR CONTINUES TO HAVE A DIFFICULT TIME PICKING
UP THE BANDING...GIVEN ITS LOWEST SCAN AROUND 7KFT IN THIS AREA.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 503 AM EST SAT DEC 14 2013
WV IMAGERY AND RAP ANALYSIS SHOW A LONG WAVE TROUGH OVER THE
CENTRAL CONUS...WITH MUCH OF THE ENERGY IN THE SOUTHERN STREAM
MOVING THROUGH THE SOUTHERN THIRD OF THE CONUS. CLOSER TO THE UPPER
GREAT LAKES...A SHORTWAVE IS CURRENTLY TRACKING THROUGH SOUTHERN
MANITOBA AND INTO NORTHERN MINNESOTA AT THIS TIME...WITH A BROAD
AREA OF MOISTURE AHEAD OF THIS WAVE IN MN/WI/MI. AT THE SURFACE...A
ELONGATED AREA OF 1034MB HIGH PRESSURE STRETCHES FROM LAKE WINNIPEG
EAST-SOUTHEAST INTO SOUTHWEST QUEBEC...WHILE A TROUGH STRETCHES
NORTHEAST INTO SOUTHERN WISCONSIN FROM A 1007MB LOW IN NORTH
CENTRAL TEXAS. THE FORCING FROM THE SHORTWAVE AND INCREASED
MOISTURE AHEAD OF IT HAS LED TO -SHSN OVER MINNESOTA OVER THE LAST
SEVERAL HOURS AND THEY HAVE EXPANDED EAST INTO WESTERN WISCONSIN.
CLOSER TO THE U.P. 850MB TEMPS OF -17 TO -20C OVER THE CWA HAS
COMBINED WITH LIGHT NORTHEAST TO EASTERLY FLOW TO LEAD TO LIGHT
LAKE EFFECT SNOW SHOWERS OVER SOUTH CENTRAL LAKE SUPERIOR. IT HAS
FINALLY STARTED TO PUSH TO THE NORTHEAST AS THE LOW LEVEL WINDS HAVE
SWITCHED TO THE SOUTH. INVERSION HEIGHTS OF 3-4KFT ON 00Z KINL
SOUNDING AND 08Z KMQT VAD PROFILE ARE LIKELY THE MAIN LIMITING
FACTOR TO THE SNOW OVERNIGHT...IN ADDITION TO THE VARIABLE LOW LEVEL
FLOW. FARTHER SOUTH...LAKE ENHANCED SNOWFALL CONTINUES OFF
LAKE MICHIGAN IN EAST CENTRAL AND PARTS OF NORTHEAST WISCONSIN.
THERE WAS A STRONGER BAND AFFECTING OCONTO EARLIER IN THE
NIGHT...BUT IT HAS SINCE WEAKENED. THERE ARE SOME HINTS THAT THE
LAKE EFFECT IS NEARING MENOMINEE...BUT VISIBILITIES THERE ARE STILL
10SM.
MUCH OF THE FORECAST FOR THE SHORT TERM WILL FOCUS ON THE SHORTWAVE
AND LAKE EFFECT/ENHANCED SNOWFALL UNDER VEERING LOW LEVEL WINDS TO
THE SOUTHEAST THROUGH THE EVENING. AS THE SHORTWAVE SHIFTS INTO
WISCONSIN AND UPPER MICHIGAN THIS AFTERNOON...A INVERTED TROUGH WILL
DEVELOP NORTHWEST FROM THE LOW MOVING INTO THE MID ATLANTIC STATES.
00Z KINL SOUNDING FAIRLY REPRESENTATIVE OF THE LIMITED MOISTURE IN
LOWER LEVELS ROTATING AROUND THE HIGH (VERY DRY BETWEEN
940-700MB)...BUT EXPECT THAT TO GIVEWAY FROM SOUTHWEST TO NORTHEAST
LATE THIS MORNING AND CONTINUE INTO THE AFTERNOON. ALREADY FAIRLY
MOIST ON THE 00Z KGRB SOUNDING AND WITH THAT CLOSE PROXIMITY AND
LIGHT NORTHEASTERLY PUSH AROUND THE HIGH...THE DRIER AIR SHOULD GIVE
AWAY FAIRLY EASILY. FORCING FROM THE SHORTWAVE AND INVERTED TROUGH
WILL DEVELOP LIGHT SNOW ACROSS MUCH OF THE AREA LATE THIS MORNING
BEFORE DIMINISHING FROM WEST TO EAST THROUGH THE LATE AFTERNOON AND
EVENING HOURS. FOCUS TURNS TO LAKE EFFECT/ENHANCED SNOWFALL.
FIRST...THE SNOW OVER SOUTH CENTRAL LAKE SUPERIOR SHOULD CONTINUE
TO DRIFT NORTHWEST THIS MORNING AND BRIEFLY CROSS THE KEWEENAW
PENINSULA BEFORE MOVING BACK INTO LAKE SUPERIOR. THE MAIN AREA OF
CONCERN IS FOR LAKE ENHANCED SNOWFALL ALONG THE BAY OF GREEN BAY.
INDICATIONS ARE THERE FROM THE MODELS AND THE DELTA-T VALUES
OF 18 TO 21 SUPPORT IT...BUT HIGHER RESOLUTION MODELS WHICH
TRADITIONALLY OVER DO QPF ARE STRUGGLING TO PUT OUT ANY SIGNIFICANT
VALUES OVER SOUTHERN MENOMINEE AND SOUTHEAST DELTA COUNTIES TODAY.
HAVE A FEELING THAT THE STRUGGLE TO PUT OUT ANY DECENT QPF IS
RELATED TO THE LOW LEVEL SHEAR INDICATED BY THE MODELS. THIS CAN BE
SEEN AT THE PRESENT TIME IN EAST CENTRAL WISCONSIN WHERE WINDS ARE
PREDOMINATELY EASTERLY IN THE LOWER LEVELS AND LAKE ENHANCEMENT IS
OCCURRING. BUT FARTHER NORTH ACROSS THE BAY OF GREEN BAY...THE DRIER
AIR COMBINED WITH WINDS VARYING IN DIRECTION DEPENDING ON LEVEL
(850MB VEERING SOUTHEAST...925MB STAYING MAINLY EASTERLY...AND
SURFACE WINDS NORTHEASTERLY) HAS BEEN LIMITING DEVELOPMENT THUS
FAR. THIS WILL LIKELY CONTINUE THROUGH THE AFTERNOON UNTIL THE
TROUGH DEVELOPS ACROSS THE AREA AND FOCUSES WINDS OUT OF THE
SOUTHEASTERLY DIRECTION THIS EVENING. AM WONDERING IF THIS SHEAR
WILL BE ENOUGH TO LIMIT ANY REAL STRONG LAKE ENHANCED BANDS. IN
ADDITION...INVERSION HEIGHTS AROUND MENOMINEE THIS MORNING ARE
AROUND 5-6KFT AND REMAINS THROUGH MUCH OF TODAY...LIKELY LIMITING
STRONG ENHANCEMENT AND HIGHER TOTALS. THEY ARE A LITTLE HIGHER
AROUND ESCANABA (6-7KFT THIS AFTERNOON/EVENING) AND WHEN COMBINED
WITH THE MORE UNIFORM FLOW THIS EVENING...THINK THAT IS WHEN THEY
WILL HAVE THE BEST OPPORTUNITY FOR MODERATE SNOWFALL. ON THE
POSITIVE SIDE...MUCH OF THE LAKE ENHANCED FORCING IS IN OR JUST
BELOW THE DGZ AND ALLOW FOR SNOW RATIOS TO BE HIGHER AND AROUND 20
TO 1. UNFORTUNATELY...DEALING WITH AROUND 20-1 SNOW RATIOS MAKES FOR
A DIFFICULT TIME ON PINNING DOWN AMOUNTS ON THESE LOWER END QPF
AMOUNTS. MODEL COBB SNOW AMOUNTS ARE ALL OVER THE BOARD WITH 12Z NAM
FOR KESC GIVING AROUND 3.5-4IN AND OUR LOCAL 00Z WRF-ARW HAS
3-3.8IN...WHILE THE 08Z RAP IS GIVING 1.3IN THROUGH 02Z. 03Z SREF
MEAN HAS 2.3-3.0 AND THINK THAT IS A REASONABLE COMPROMISE. AMOUNTS
FOR KMNM HAVE A SIMILAR RANGE...WITH THE HIGHEST AMOUNTS FROM THE
MODELS OF 4-5INCHES...BUT THOSE RUNS HAD 2IN OF ACCUMULATION ALREADY
EVEN THOUGH IT HASN/T EVEN STARTED SNOWING. THEREFORE...OPTED TO
LOWER AMOUNTS ABOUT AN INCH AND MAY NEED TO DO MORE IF THE SNOW
STRUGGLES TO DEVELOP THIS MORNING. STILL THINK THE HIGHEST AMOUNTS
WILL BE OVER THE GARDEN PENINSULA...WHERE AMOUNTS COULD REACH 5
INCHES.
OVERALL VERY UNCERTAIN ON SNOWFALL AMOUNTS FOR MENOMINEE AND DELTA
COUNTIES TODAY...LARGELY DUE TO THE LOW LEVEL SHEAR THAT LOOKS LIKE
IT WILL OCCUR. A LITTLE MORE CONFIDENCE IN PORTIONS OF DELTA AS
WINDS BECOME MORE FAVORABLE THIS EVENING AND THERE IS LESS
SHEAR...BUT EVEN THEN THE BANDS WILL LIKELY BE MOVING ENOUGH TO THE
EAST TO LIMIT SIGNIFICANT ACCUMULATIONS. THEREFORE...WILL KEEP THE
ADVISORY GOING FOR NOW (WITH WEAKER WORDING AND GREATER RANGE IN
TOTALS TO SHOW UNCERTAINTY) SINCE THEY SHOULD SEE SOME SNOW AND
ALLOW THE DAY SHIFT TO ASSESS THE SITUATION THROUGH THE MORNING.
WITH THE UNCERTAINTY...DID NOT EXPAND ADVISORY TO SOUTHERN
SCHOOLCRAFT FOR TONIGHT EVEN THOUGH THERE TOTALS ARE IN THE SAME
RANGE AS SOUTHERN DELTA COUNTY.
A SURFACE LOW LOOKS TO DEVELOP ALONG THE SURFACE TROUGH OVER
NORTHERN LAKE SUPERIOR TONIGHT AS A SECONDARY AND STRONGER
SHORTWAVE DROPS OVER LAKE SUPERIOR. THE FLOW AROUND THE LOW WILL
KEEP MUCH OF THE LAKE EFFECT AWAY FROM THE LAKE SUPERIOR SHORELINES
THIS EVENING...BEFORE WINDS SHIFT TO THE WEST-NORTHWEST OVER THE
WESTERN LAKE OVERNIGHT WITH THE LOW MOVING INTO THE EASTERN LAKE.
THEREFORE...SHOULD SEE LAKE EFFECT INCREASING OVER THE WESTERN HALF
OF THE CWA OVERNIGHT WITH THAT WINDSHIFT AND THE INTENSIFYING LOW
OVER THE NORTHERN/EASTERN LAKE. INVERSION HEIGHTS DO LOOK TO IMPROVE
TO AROUND 10KFT OVER THE WESTERN LAKE OVERNIGHT AND WITH THE HELP OF
THE ADDITIONAL MOISTENING TODAY FROM THE SURFACE TROUGH...THAT AREA
SHOULD BE ABLE TO REALIZE THOSE FAIRLY HIGH INVERSION HEIGHTS.
850MB TEMPS FALL FROM -16C AT 06Z TO -20C BY 12Z SUNDAY...SO LAKE
INSTABILITY IS PRESENT AND BUFKIT SOUNDINGS ARE SHOWING LAKE INDUCED
CAPES IN THE 400-600 J/KG RANGE. IN ADDITION...THE EXTRA
FORCING FROM THE SHORTWAVE (INCREASING MID LEVEL Q-VECTOR
CONVERGENCE) WILL PRODUCE A CONDUCIVE PERIOD FOR LAKE EFFECT
SNOWFALL. THUS...WOULD EXPECT THERE TO BE A FAIRLY DECENT BURST OF
SNOW AFTER ABOUT 06Z FROM THE PORKIES UP THROUGH THE KEWEENAW
PENINSULA AS THE WINDS SHIFT TO THE WNW. HIGH RESOLUTION MODELS
AGREE FAIRLY WELL WITH THIS TIMING AND WILL BUMP POPS UP TO 100
PERCENT IN THOSE AREAS OVERNIGHT. WITH MUCH OF THE FORCING RIGHT
WITHIN AND A LITTLE ABOVE THE DGZ...SHOULD SEE FAIRLY DECENT SNOW
RATIOS (AROUND 20-22 TO 1) AND WOULD EXPECT AT LEAST OF COUPLE HOUR
PERIOD OF 1 IN/HR SNOWFALL AFTER 06Z IN SOME LOCATIONS.
THEREFORE...HAVE TRENDED THE SNOWFALL FORECAST UP A LITTLE BIT WITH
A GENERAL 1-3 INCH AMOUNTS AND HAVE THE HIGHEST VALUES OVER THE
HIGHER TERRAIN FROM THE PORKIES THROUGH THE KEWEENAW.
OVER THE REST OF THE CWA...WINDS WILL BE SHIFTING FROM
SOUTH-SOUTHEAST TO WESTERLY AS THE LOW MOVES TO THE EAST THROUGH
THE NIGHT. EXPECT THE ONGOING LAKE EFFECT OFF LAKE MICHIGAN TO
FOLLOW THAT EASTWARD PUSH THROUGH THE NIGHT AND LARGELY INFLUENCING
DELTA COUNTY IN THE EVENING AND THEN SCHOOLCRAFT AND SOUTHERN LUCE
COUNTIES DURING THE OVERNIGHT HOURS. THE EXPECTED EASTWARD MOVEMENT
OF THE LAKE ENHANCED SNOWFALL SHOULD LIMIT THE SNOWFALL AMOUNTS OVER
MOST OF THOSE AREAS TO A QUICK 1-3IN OF SNOW TONIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 403 AM EST SAT DEC 14 2013
NAM SHOWS A CLOSED 500 MB LOW NORTH OF LAKE SUPERIOR 12Z SUN WHICH
MOVES SOUTHEAST ON SUN. ANOTHER UPPER TROUGH DIGS SOUTHEAST INTO THE
AREA FOR MON NIGHT. NAM SHOWS SOME 850-500 MB Q-VECTOR CONVERGENCE
12Z MON MOVING INTO THE AREA WITH SOME DEEPER MOISTURE WHICH REMAINS
INTO MON NIGHT. LAKE EFFECT SNOW WILL CONTINUE THIS PERIOD FOR
SUNDAY INTO SUNDAY EVENING WITH COLD AIR IN NORTHWEST AND NORTH LAKE
EFFECT SNOW BELTS. ON MONDAY...THERE COULD BE SOME LAKE ENHANCEMENT
MON AFTERNOON AND EVENING OFF OF LAKE MICHIGAN AND HAVE THIS COVERED
WITH LIKELY POPS IN THE EASTERN CWA FOR SOUTHWEST WIND FLOW. HAVE
LIKELY POPS MON NIGHT ACROSS THE KEWEENAW FOR WEST FLOW LAKE EFFECT
SNOW BELTS. DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST FOR
TEMPERATURES.
IN THE EXTENDED...GFS AND ECMWF SHOW A BROAD 500 MB TROUGH OVER THE
CENTRAL AND EASTERN U.S. 12Z TUE. THIS TROUGH PULLS EAST 12Z WED
WITH SFC HIGH PRESSURE ALONG THE MISSISSIPPI RIVER VALLEY. SFC LOW
PRESSURE MOVES INTO THE CENTRAL PLAINS 12Z THU. GFS AND ECMWF SHOW A
500 MB TROUGH OVER THE NORTHERN PLAINS AND DESERT SW 12Z FRI. COLDER
THAN NORMAL TEMPERATURES LOOK TO CONTINUE THIS FORECAST PERIOD
EXCEPT FOR A BRIEF RESPITE ON THU INTO FRIDAY BEFORE COLD AIR
ARRIVES AGAIN. STILL LOOKS COLD ENOUGH WITH A WARM FRONT TO THE
SOUTH AND WARM AIR JUST TO THE SOUTH TO KEEP THE PCPN AS SNOW ON
THU...BUT WILL HAVE TO WATCH THIS AS THERE IS A LOW POSSIBILITY OF
SOME MIXED PCPN IN THE FAR SOUTH. BASICALLY...LAKE EFFECT SNOW WILL
CONTINUE THROUGH WED BEFORE SYSTEM KICKS OUT ON THU. COLD AIR THEN
ARRIVES AGAIN LATE ON FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 133 PM EST SAT DEC 14 2013
CEILINGS CONTINUE TO FLUCTUATE BETWEEN VFR AND MVFR...WITH SMALL
SNOWFLAKES RESULTING IN VIS RESTRICTIONS OF IFR BACK UP THROUGH VFR.
A SFC LOW OVER N AND W LAKE SUPERIOR WILL SLIDE ACROSS THE W
COUNTIES OF UPPER MI...INCLUDING THE IWD AND CMX TAF SITES BETWEEN
05-09Z SUNDAY. BEHIND THE EXITING LOW...A POCKET OF COLDER AIR ALOFT
ACCOMPANIED BY ONSHORE/UPSLOPE WINDS OFF LAKE SUPERIOR WILL RESULT
IN THE BEST CHANCE OF ACCUMULATING SNOW AND WORST FLYING CONDITIONS
SUNDAY FROM APPROX 10-18Z...WITH A SLOW IMPROVEMENT SUNDAY AFTERNOON
AS WINDS DIMINISH AND BECOME MORE NORTHERLY. THE NW WINDS WILL TAKE
OVER AT SAW BEHIND THE SFC LOW AROUND 12Z SUNDAY. WITH LESS THAN
FAVORABLE WINDS...WILL EXPECT VFR TO HIGH END MVFR CEILINGS/VIS
BEHIND THE LOW AND ITS ASSOCIATED TROUGH.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 503 AM EST SAT DEC 14 2013
HIGH PRESSURE OVER SOUTHERN ONTARIO EARLY THIS MORNING WILL MOVE
EAST INTO SOUTHWEST QUEBEC TODAY WHILE A LOW PRESSURE SYSTEM TAKING
SHAPE IN THE LOWER MISSISSIPPI VALLEY MOVES INTO THE MID ATLANTIC
STATES. WHILE THIS OCCURS...A LOW PRESSURE TROUGH WILL SETUP OVER
THE UPPER GREAT LAKES THIS AFTERNOON AND THEN DEVELOP INTO A WEAK
LOW TONIGHT BEFORE SHIFTING SOUTHEAST SUNDAY AFTERNOON INTO SUNDAY
NIGHT. EXPECT GENERALLY LIGHT WINDS ALONG THIS TROUGH TODAY AND
TONIGHT...BUT DO EXPECT THEM TO INCREASE OUT OF THE NORTHWEST ON
SUNDAY...WITH GUSTS TO 30KTS EXPECTED SUNDAY AFTERNOON/EVENING.
WINDS WILL QUICKLY DIMINISH LATE SUNDAY NIGHT BEFORE INCREASING OUT
OF THE SOUTHWEST ON MONDAY (GUSTS TO 30KTS) AHEAD OF A CLIPPER LIKE
LOW MOVING SOUTHEAST THROUGH SOUTHERN CANADA AND BRUSHING THE UPPER
GREAT LAKES ON MONDAY NIGHT AND TUESDAY. AS THE COLD FRONT SWEEPS
THROUGH ON MONDAY NIGHT...EXPECT WINDS TO SHIFT TO THE NORTHWEST
AND BE IN THE 20-30KT RANGE. THERE COULD EVEN BE SOME GALE FORCE
GUSTS TO 35KTS TUESDAY INTO TUESDAY NIGHT. ANOTHER QUICK HIGH
PRESSURE RIDGE WILL MOVE IN ON WEDNESDAY AND DIMINISH WINDS AHEAD
OF LOW DEVELOPING IN THE CENTRAL PLAINS AND EXPECTED TO MOVE
THROUGH THE GREAT LAKES REGION ON THURSDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY UNTIL 1 AM EST SUNDAY FOR MIZ013.
LAKE EFFECT SNOW ADVISORY UNTIL 8 PM CST THIS EVENING FOR MIZ012.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KF
SHORT TERM...SRF
LONG TERM...07
AVIATION...KF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
626 AM EST SAT DEC 14 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 503 AM EST SAT DEC 14 2013
WV IMAGERY AND RAP ANALYSIS SHOW A LONG WAVE TROUGH OVER THE
CENTRAL CONUS...WITH MUCH OF THE ENERGY IN THE SOUTHERN STREAM
MOVING THROUGH THE SOUTHERN THIRD OF THE CONUS. CLOSER TO THE UPPER
GREAT LAKES...A SHORTWAVE IS CURRENTLY TRACKING THROUGH SOUTHERN
MANITOBA AND INTO NORTHERN MINNESOTA AT THIS TIME...WITH A BROAD
AREA OF MOISTURE AHEAD OF THIS WAVE IN MN/WI/MI. AT THE SURFACE...A
ELONGATED AREA OF 1034MB HIGH PRESSURE STRETCHES FROM LAKE WINNIPEG
EAST-SOUTHEAST INTO SOUTHWEST QUEBEC...WHILE A TROUGH STRETCHES
NORTHEAST INTO SOUTHERN WISCONSIN FROM A 1007MB LOW IN NORTH
CENTRAL TEXAS. THE FORCING FROM THE SHORTWAVE AND INCREASED
MOISTURE AHEAD OF IT HAS LED TO -SHSN OVER MINNESOTA OVER THE LAST
SEVERAL HOURS AND THEY HAVE EXPANDED EAST INTO WESTERN WISCONSIN.
CLOSER TO THE U.P. 850MB TEMPS OF -17 TO -20C OVER THE CWA HAS
COMBINED WITH LIGHT NORTHEAST TO EASTERLY FLOW TO LEAD TO LIGHT
LAKE EFFECT SNOW SHOWERS OVER SOUTH CENTRAL LAKE SUPERIOR. IT HAS
FINALLY STARTED TO PUSH TO THE NORTHEAST AS THE LOW LEVEL WINDS HAVE
SWITCHED TO THE SOUTH. INVERSION HEIGHTS OF 3-4KFT ON 00Z KINL
SOUNDING AND 08Z KMQT VAD PROFILE ARE LIKELY THE MAIN LIMITING
FACTOR TO THE SNOW OVERNIGHT...IN ADDITION TO THE VARIABLE LOW LEVEL
FLOW. FARTHER SOUTH...LAKE ENHANCED SNOWFALL CONTINUES OFF
LAKE MICHIGAN IN EAST CENTRAL AND PARTS OF NORTHEAST WISCONSIN.
THERE WAS A STRONGER BAND AFFECTING OCONTO EARLIER IN THE
NIGHT...BUT IT HAS SINCE WEAKENED. THERE ARE SOME HINTS THAT THE
LAKE EFFECT IS NEARING MENOMINEE...BUT VISIBILITIES THERE ARE STILL
10SM.
MUCH OF THE FORECAST FOR THE SHORT TERM WILL FOCUS ON THE SHORTWAVE
AND LAKE EFFECT/ENHANCED SNOWFALL UNDER VEERING LOW LEVEL WINDS TO
THE SOUTHEAST THROUGH THE EVENING. AS THE SHORTWAVE SHIFTS INTO
WISCONSIN AND UPPER MICHIGAN THIS AFTERNOON...A INVERTED TROUGH WILL
DEVELOP NORTHWEST FROM THE LOW MOVING INTO THE MID ATLANTIC STATES.
00Z KINL SOUNDING FAIRLY REPRESENTATIVE OF THE LIMITED MOISTURE IN
LOWER LEVELS ROTATING AROUND THE HIGH (VERY DRY BETWEEN
940-700MB)...BUT EXPECT THAT TO GIVEWAY FROM SOUTHWEST TO NORTHEAST
LATE THIS MORNING AND CONTINUE INTO THE AFTERNOON. ALREADY FAIRLY
MOIST ON THE 00Z KGRB SOUNDING AND WITH THAT CLOSE PROXIMITY AND
LIGHT NORTHEASTERLY PUSH AROUND THE HIGH...THE DRIER AIR SHOULD GIVE
AWAY FAIRLY EASILY. FORCING FROM THE SHORTWAVE AND INVERTED TROUGH
WILL DEVELOP LIGHT SNOW ACROSS MUCH OF THE AREA LATE THIS MORNING
BEFORE DIMINISHING FROM WEST TO EAST THROUGH THE LATE AFTERNOON AND
EVENING HOURS. FOCUS TURNS TO LAKE EFFECT/ENHANCED SNOWFALL.
FIRST...THE SNOW OVER SOUTH CENTRAL LAKE SUPERIOR SHOULD CONTINUE
TO DRIFT NORTHWEST THIS MORNING AND BRIEFLY CROSS THE KEWEENAW
PENINSULA BEFORE MOVING BACK INTO LAKE SUPERIOR. THE MAIN AREA OF
CONCERN IS FOR LAKE ENHANCED SNOWFALL ALONG THE BAY OF GREEN BAY.
INDICATIONS ARE THERE FROM THE MODELS AND THE DELTA-T VALUES
OF 18 TO 21 SUPPORT IT...BUT HIGHER RESOLUTION MODELS WHICH
TRADITIONALLY OVER DO QPF ARE STRUGGLING TO PUT OUT ANY SIGNIFICANT
VALUES OVER SOUTHERN MENOMINEE AND SOUTHEAST DELTA COUNTIES TODAY.
HAVE A FEELING THAT THE STRUGGLE TO PUT OUT ANY DECENT QPF IS
RELATED TO THE LOW LEVEL SHEAR INDICATED BY THE MODELS. THIS CAN BE
SEEN AT THE PRESENT TIME IN EAST CENTRAL WISCONSIN WHERE WINDS ARE
PREDOMINATELY EASTERLY IN THE LOWER LEVELS AND LAKE ENHANCEMENT IS
OCCURRING. BUT FARTHER NORTH ACROSS THE BAY OF GREEN BAY...THE DRIER
AIR COMBINED WITH WINDS VARYING IN DIRECTION DEPENDING ON LEVEL
(850MB VEERING SOUTHEAST...925MB STAYING MAINLY EASTERLY...AND
SURFACE WINDS NORTHEASTERLY) HAS BEEN LIMITING DEVELOPMENT THUS
FAR. THIS WILL LIKELY CONTINUE THROUGH THE AFTERNOON UNTIL THE
TROUGH DEVELOPS ACROSS THE AREA AND FOCUSES WINDS OUT OF THE
SOUTHEASTERLY DIRECTION THIS EVENING. AM WONDERING IF THIS SHEAR
WILL BE ENOUGH TO LIMIT ANY REAL STRONG LAKE ENHANCED BANDS. IN
ADDITION...INVERSION HEIGHTS AROUND MENOMINEE THIS MORNING ARE
AROUND 5-6KFT AND REMAINS THROUGH MUCH OF TODAY...LIKELY LIMITING
STRONG ENHANCEMENT AND HIGHER TOTALS. THEY ARE A LITTLE HIGHER
AROUND ESCANABA (6-7KFT THIS AFTERNOON/EVENING) AND WHEN COMBINED
WITH THE MORE UNIFORM FLOW THIS EVENING...THINK THAT IS WHEN THEY
WILL HAVE THE BEST OPPORTUNITY FOR MODERATE SNOWFALL. ON THE
POSITIVE SIDE...MUCH OF THE LAKE ENHANCED FORCING IS IN OR JUST
BELOW THE DGZ AND ALLOW FOR SNOW RATIOS TO BE HIGHER AND AROUND 20
TO 1. UNFORTUNATELY...DEALING WITH AROUND 20-1 SNOW RATIOS MAKES FOR
A DIFFICULT TIME ON PINNING DOWN AMOUNTS ON THESE LOWER END QPF
AMOUNTS. MODEL COBB SNOW AMOUNTS ARE ALL OVER THE BOARD WITH 12Z NAM
FOR KESC GIVING AROUND 3.5-4IN AND OUR LOCAL 00Z WRF-ARW HAS
3-3.8IN...WHILE THE 08Z RAP IS GIVING 1.3IN THROUGH 02Z. 03Z SREF
MEAN HAS 2.3-3.0 AND THINK THAT IS A REASONABLE COMPROMISE. AMOUNTS
FOR KMNM HAVE A SIMILAR RANGE...WITH THE HIGHEST AMOUNTS FROM THE
MODELS OF 4-5INCHES...BUT THOSE RUNS HAD 2IN OF ACCUMULATION ALREADY
EVEN THOUGH IT HASN/T EVEN STARTED SNOWING. THEREFORE...OPTED TO
LOWER AMOUNTS ABOUT AN INCH AND MAY NEED TO DO MORE IF THE SNOW
STRUGGLES TO DEVELOP THIS MORNING. STILL THINK THE HIGHEST AMOUNTS
WILL BE OVER THE GARDEN PENINSULA...WHERE AMOUNTS COULD REACH 5
INCHES.
OVERALL VERY UNCERTAIN ON SNOWFALL AMOUNTS FOR MENOMINEE AND DELTA
COUNTIES TODAY...LARGELY DUE TO THE LOW LEVEL SHEAR THAT LOOKS LIKE
IT WILL OCCUR. A LITTLE MORE CONFIDENCE IN PORTIONS OF DELTA AS
WINDS BECOME MORE FAVORABLE THIS EVENING AND THERE IS LESS
SHEAR...BUT EVEN THEN THE BANDS WILL LIKELY BE MOVING ENOUGH TO THE
EAST TO LIMIT SIGNIFICANT ACCUMULATIONS. THEREFORE...WILL KEEP THE
ADVISORY GOING FOR NOW (WITH WEAKER WORDING AND GREATER RANGE IN
TOTALS TO SHOW UNCERTAINTY) SINCE THEY SHOULD SEE SOME SNOW AND
ALLOW THE DAY SHIFT TO ASSESS THE SITUATION THROUGH THE MORNING.
WITH THE UNCERTAINTY...DID NOT EXPAND ADVISORY TO SOUTHERN
SCHOOLCRAFT FOR TONIGHT EVEN THOUGH THERE TOTALS ARE IN THE SAME
RANGE AS SOUTHERN DELTA COUNTY.
A SURFACE LOW LOOKS TO DEVELOP ALONG THE SURFACE TROUGH OVER
NORTHERN LAKE SUPERIOR TONIGHT AS A SECONDARY AND STRONGER
SHORTWAVE DROPS OVER LAKE SUPERIOR. THE FLOW AROUND THE LOW WILL
KEEP MUCH OF THE LAKE EFFECT AWAY FROM THE LAKE SUPERIOR SHORELINES
THIS EVENING...BEFORE WINDS SHIFT TO THE WEST-NORTHWEST OVER THE
WESTERN LAKE OVERNIGHT WITH THE LOW MOVING INTO THE EASTERN LAKE.
THEREFORE...SHOULD SEE LAKE EFFECT INCREASING OVER THE WESTERN HALF
OF THE CWA OVERNIGHT WITH THAT WINDSHIFT AND THE INTENSIFYING LOW
OVER THE NORTHERN/EASTERN LAKE. INVERSION HEIGHTS DO LOOK TO IMPROVE
TO AROUND 10KFT OVER THE WESTERN LAKE OVERNIGHT AND WITH THE HELP OF
THE ADDITIONAL MOISTENING TODAY FROM THE SURFACE TROUGH...THAT AREA
SHOULD BE ABLE TO REALIZE THOSE FAIRLY HIGH INVERSION HEIGHTS.
850MB TEMPS FALL FROM -16C AT 06Z TO -20C BY 12Z SUNDAY...SO LAKE
INSTABILITY IS PRESENT AND BUFKIT SOUNDINGS ARE SHOWING LAKE INDUCED
CAPES IN THE 400-600 J/KG RANGE. IN ADDITION...THE EXTRA
FORCING FROM THE SHORTWAVE (INCREASING MID LEVEL Q-VECTOR
CONVERGENCE) WILL PRODUCE A CONDUCIVE PERIOD FOR LAKE EFFECT
SNOWFALL. THUS...WOULD EXPECT THERE TO BE A FAIRLY DECENT BURST OF
SNOW AFTER ABOUT 06Z FROM THE PORKIES UP THROUGH THE KEWEENAW
PENINSULA AS THE WINDS SHIFT TO THE WNW. HIGH RESOLUTION MODELS
AGREE FAIRLY WELL WITH THIS TIMING AND WILL BUMP POPS UP TO 100
PERCENT IN THOSE AREAS OVERNIGHT. WITH MUCH OF THE FORCING RIGHT
WITHIN AND A LITTLE ABOVE THE DGZ...SHOULD SEE FAIRLY DECENT SNOW
RATIOS (AROUND 20-22 TO 1) AND WOULD EXPECT AT LEAST OF COUPLE HOUR
PERIOD OF 1 IN/HR SNOWFALL AFTER 06Z IN SOME LOCATIONS.
THEREFORE...HAVE TRENDED THE SNOWFALL FORECAST UP A LITTLE BIT WITH
A GENERAL 1-3 INCH AMOUNTS AND HAVE THE HIGHEST VALUES OVER THE
HIGHER TERRAIN FROM THE PORKIES THROUGH THE KEWEENAW.
OVER THE REST OF THE CWA...WINDS WILL BE SHIFTING FROM
SOUTH-SOUTHEAST TO WESTERLY AS THE LOW MOVES TO THE EAST THROUGH
THE NIGHT. EXPECT THE ONGOING LAKE EFFECT OFF LAKE MICHIGAN TO
FOLLOW THAT EASTWARD PUSH THROUGH THE NIGHT AND LARGELY INFLUENCING
DELTA COUNTY IN THE EVENING AND THEN SCHOOLCRAFT AND SOUTHERN LUCE
COUNTIES DURING THE OVERNIGHT HOURS. THE EXPECTED EASTWARD MOVEMENT
OF THE LAKE ENHANCED SNOWFALL SHOULD LIMIT THE SNOWFALL AMOUNTS OVER
MOST OF THOSE AREAS TO A QUICK 1-3IN OF SNOW TONIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 403 AM EST SAT DEC 14 2013
NAM SHOWS A CLOSED 500 MB LOW NORTH OF LAKE SUPERIOR 12Z SUN WHICH
MOVES SOUTHEAST ON SUN. ANOTHER UPPER TROUGH DIGS SOUTHEAST INTO THE
AREA FOR MON NIGHT. NAM SHOWS SOME 850-500 MB Q-VECTOR CONVERGENCE
12Z MON MOVING INTO THE AREA WITH SOME DEEPER MOISTURE WHICH REMAINS
INTO MON NIGHT. LAKE EFFECT SNOW WILL CONTINUE THIS PERIOD FOR
SUNDAY INTO SUNDAY EVENING WITH COLD AIR IN NORTHWEST AND NORTH LAKE
EFFECT SNOW BELTS. ON MONDAY...THERE COULD BE SOME LAKE ENHANCEMENT
MON AFTERNOON AND EVENING OFF OF LAKE MICHIGAN AND HAVE THIS COVERED
WITH LIKELY POPS IN THE EASTERN CWA FOR SOUTHWEST WIND FLOW. HAVE
LIKELY POPS MON NIGHT ACROSS THE KEWEENAW FOR WEST FLOW LAKE EFFECT
SNOW BELTS. DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST FOR
TEMPERATURES.
IN THE EXTENDED...GFS AND ECMWF SHOW A BROAD 500 MB TROUGH OVER THE
CENTRAL AND EASTERN U.S. 12Z TUE. THIS TROUGH PULLS EAST 12Z WED
WITH SFC HIGH PRESSURE ALONG THE MISSISSIPPI RIVER VALLEY. SFC LOW
PRESSURE MOVES INTO THE CENTRAL PLAINS 12Z THU. GFS AND ECMWF SHOW A
500 MB TROUGH OVER THE NORTHERN PLAINS AND DESERT SW 12Z FRI. COLDER
THAN NORMAL TEMPERATURES LOOK TO CONTINUE THIS FORECAST PERIOD
EXCEPT FOR A BRIEF RESPITE ON THU INTO FRIDAY BEFORE COLD AIR
ARRIVES AGAIN. STILL LOOKS COLD ENOUGH WITH A WARM FRONT TO THE
SOUTH AND WARM AIR JUST TO THE SOUTH TO KEEP THE PCPN AS SNOW ON
THU...BUT WILL HAVE TO WATCH THIS AS THERE IS A LOW POSSIBILITY OF
SOME MIXED PCPN IN THE FAR SOUTH. BASICALLY...LAKE EFFECT SNOW WILL
CONTINUE THROUGH WED BEFORE SYSTEM KICKS OUT ON THU. COLD AIR THEN
ARRIVES AGAIN LATE ON FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 626 AM EST SAT DEC 14 2013
A SHORTWAVE AND DEVELOPING INVERTED TROUGH MOVING ACROSS UPPER
MICHIGAN TODAY WILL LEAD TO INCREASING CHANCES OF LIGHT SNOW
SHOWERS AND LOWERING CEILINGS THROUGH THE DAY. EXPECT THE SNOW AND
LOWER CEILINGS TO IMPACT KIWD FIRST AND THEN SPREAD TO KCMX/KSAW
LATE INTO THE AFTERNOON AND EARLY EVENING. UPSTREAM OBS GENERALLY
INDICATE MVFR/VFR VISIBILITIES WITH THE LIGHT SNOW AND WILL
CONTINUE TO FOLLOW THAT TREND. A LITTLE UNCERTAIN ON HOW SOON THE
CEILINGS AT KIWD WILL GO DOWN DUE TO THE UNFAVORABLE EAST-SOUTHEAST
FLOW...SO HAVE HELD THEM UP UNTIL THE BEST SNOW OCCURS IN THE
AFTERNOON. FOR KCMX/KSAW THIS MORNING...THE LAKE EFFECT SNOW SHOWERS
THAT WERE IMPACTING KSAW WILL CONTINUE NW THROUGH NOON. THINK THE
SHOWERS WILL BRUSH OR MISS KCMX TO THE NORTHEAST...SO HAVE TRENDED
VISIBILITIES UP THIS MORNING AND KEPT CEILINGS AT MVFR. DID BRING
CEILINGS DOWN AT KSAW EARLIER THAN THE OTHER SITES DUE TO FAVORABLE
UPSLOPE SOUTHEAST FLOW LATE THIS AFTERNOON.
AS A LOW DEVELOPS ALONG THE TROUGH IN NORTHERN LAKE SUPERIOR THIS
EVENING AND THEN MOVES SOUTHEAST OVERNIGHT...EXPECT A COLD FRONT
TO SWEEP ACROSS UPPER MICHIGAN AND SHIFT WINDS TO THE NORTHWEST.
BELIEVE THERE WILL BE A STRONG LINE OF SNOW SHOWERS ALONG THIS
FRONT AND THEN TRANSITIONING TO LAKE EFFECT OVERNIGHT AND
CONTINUING INTO SUNDAY. MODELS HAVE DECENT AGREEMENT ON
TIMING...WITH IT SWEEPING THROUGH KIWD/KCMX BETWEEN 05-07Z SUNDAY
AND HAVE FOLLOWED THAT IDEA FOR THOSE SITES. THE UNFAVORABLE
WEST-NORTHWEST FLOW FOR KSAW SHOULD LEAD TO A TRANSITION TO VFR
CEILINGS/VISIBILITIES.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 503 AM EST SAT DEC 14 2013
HIGH PRESSURE OVER SOUTHERN ONTARIO EARLY THIS MORNING WILL MOVE
EAST INTO SOUTHWEST QUEBEC TODAY WHILE A LOW PRESSURE SYSTEM TAKING
SHAPE IN THE LOWER MISSISSIPPI VALLEY MOVES INTO THE MID ATLANTIC
STATES. WHILE THIS OCCURS...A LOW PRESSURE TROUGH WILL SETUP OVER
THE UPPER GREAT LAKES THIS AFTERNOON AND THEN DEVELOP INTO A WEAK
LOW TONIGHT BEFORE SHIFTING SOUTHEAST SUNDAY AFTERNOON INTO SUNDAY
NIGHT. EXPECT GENERALLY LIGHT WINDS ALONG THIS TROUGH TODAY AND
TONIGHT...BUT DO EXPECT THEM TO INCREASE OUT OF THE NORTHWEST ON
SUNDAY...WITH GUSTS TO 30KTS EXPECTED SUNDAY AFTERNOON/EVENING.
WINDS WILL QUICKLY DIMINISH LATE SUNDAY NIGHT BEFORE INCREASING OUT
OF THE SOUTHWEST ON MONDAY (GUSTS TO 30KTS) AHEAD OF A CLIPPER LIKE
LOW MOVING SOUTHEAST THROUGH SOUTHERN CANADA AND BRUSHING THE UPPER
GREAT LAKES ON MONDAY NIGHT AND TUESDAY. AS THE COLD FRONT SWEEPS
THROUGH ON MONDAY NIGHT...EXPECT WINDS TO SHIFT TO THE NORTHWEST
AND BE IN THE 20-30KT RANGE. THERE COULD EVEN BE SOME GALE FORCE
GUSTS TO 35KTS TUESDAY INTO TUESDAY NIGHT. ANOTHER QUICK HIGH
PRESSURE RIDGE WILL MOVE IN ON WEDNESDAY AND DIMINISH WINDS AHEAD
OF LOW DEVELOPING IN THE CENTRAL PLAINS AND EXPECTED TO MOVE
THROUGH THE GREAT LAKES REGION ON THURSDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY UNTIL 1 AM EST SUNDAY FOR MIZ013.
LAKE EFFECT SNOW ADVISORY UNTIL 8 PM CST THIS EVENING FOR MIZ012.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...07
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
504 AM EST SAT DEC 14 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 503 AM EST SAT DEC 14 2013
WV IMAGERY AND RAP ANALYSIS SHOW A LONG WAVE TROUGH OVER THE
CENTRAL CONUS...WITH MUCH OF THE ENERGY IN THE SOUTHERN STREAM
MOVING THROUGH THE SOUTHERN THIRD OF THE CONUS. CLOSER TO THE UPPER
GREAT LAKES...A SHORTWAVE IS CURRENTLY TRACKING THROUGH SOUTHERN
MANITOBA AND INTO NORTHERN MINNESOTA AT THIS TIME...WITH A BROAD
AREA OF MOISTURE AHEAD OF THIS WAVE IN MN/WI/MI. AT THE SURFACE...A
ELONGATED AREA OF 1034MB HIGH PRESSURE STRETCHES FROM LAKE WINNIPEG
EAST-SOUTHEAST INTO SOUTHWEST QUEBEC...WHILE A TROUGH STRETCHES
NORTHEAST INTO SOUTHERN WISCONSIN FROM A 1007MB LOW IN NORTH
CENTRAL TEXAS. THE FORCING FROM THE SHORTWAVE AND INCREASED
MOISTURE AHEAD OF IT HAS LED TO -SHSN OVER MINNESOTA OVER THE LAST
SEVERAL HOURS AND THEY HAVE EXPANDED EAST INTO WESTERN WISCONSIN.
CLOSER TO THE U.P. 850MB TEMPS OF -17 TO -20C OVER THE CWA HAS
COMBINED WITH LIGHT NORTHEAST TO EASTERLY FLOW TO LEAD TO LIGHT
LAKE EFFECT SNOW SHOWERS OVER SOUTH CENTRAL LAKE SUPERIOR. IT HAS
FINALLY STARTED TO PUSH TO THE NORTHEAST AS THE LOW LEVEL WINDS HAVE
SWITCHED TO THE SOUTH. INVERSION HEIGHTS OF 3-4KFT ON 00Z KINL
SOUNDING AND 08Z KMQT VAD PROFILE ARE LIKELY THE MAIN LIMITING
FACTOR TO THE SNOW OVERNIGHT...IN ADDITION TO THE VARIABLE LOW LEVEL
FLOW. FARTHER SOUTH...LAKE ENHANCED SNOWFALL CONTINUES OFF
LAKE MICHIGAN IN EAST CENTRAL AND PARTS OF NORTHEAST WISCONSIN.
THERE WAS A STRONGER BAND AFFECTING OCONTO EARLIER IN THE
NIGHT...BUT IT HAS SINCE WEAKENED. THERE ARE SOME HINTS THAT THE
LAKE EFFECT IS NEARING MENOMINEE...BUT VISIBILITIES THERE ARE STILL
10SM.
MUCH OF THE FORECAST FOR THE SHORT TERM WILL FOCUS ON THE SHORTWAVE
AND LAKE EFFECT/ENHANCED SNOWFALL UNDER VEERING LOW LEVEL WINDS TO
THE SOUTHEAST THROUGH THE EVENING. AS THE SHORTWAVE SHIFTS INTO
WISCONSIN AND UPPER MICHIGAN THIS AFTERNOON...A INVERTED TROUGH WILL
DEVELOP NORTHWEST FROM THE LOW MOVING INTO THE MID ATLANTIC STATES.
00Z KINL SOUNDING FAIRLY REPRESENTATIVE OF THE LIMITED MOISTURE IN
LOWER LEVELS ROTATING AROUND THE HIGH (VERY DRY BETWEEN
940-700MB)...BUT EXPECT THAT TO GIVEWAY FROM SOUTHWEST TO NORTHEAST
LATE THIS MORNING AND CONTINUE INTO THE AFTERNOON. ALREADY FAIRLY
MOIST ON THE 00Z KGRB SOUNDING AND WITH THAT CLOSE PROXIMITY AND
LIGHT NORTHEASTERLY PUSH AROUND THE HIGH...THE DRIER AIR SHOULD GIVE
AWAY FAIRLY EASILY. FORCING FROM THE SHORTWAVE AND INVERTED TROUGH
WILL DEVELOP LIGHT SNOW ACROSS MUCH OF THE AREA LATE THIS MORNING
BEFORE DIMINISHING FROM WEST TO EAST THROUGH THE LATE AFTERNOON AND
EVENING HOURS. FOCUS TURNS TO LAKE EFFECT/ENHANCED SNOWFALL.
FIRST...THE SNOW OVER SOUTH CENTRAL LAKE SUPERIOR SHOULD CONTINUE
TO DRIFT NORTHWEST THIS MORNING AND BRIEFLY CROSS THE KEWEENAW
PENINSULA BEFORE MOVING BACK INTO LAKE SUPERIOR. THE MAIN AREA OF
CONCERN IS FOR LAKE ENHANCED SNOWFALL ALONG THE BAY OF GREEN BAY.
INDICATIONS ARE THERE FROM THE MODELS AND THE DELTA-T VALUES
OF 18 TO 21 SUPPORT IT...BUT HIGHER RESOLUTION MODELS WHICH
TRADITIONALLY OVER DO QPF ARE STRUGGLING TO PUT OUT ANY SIGNIFICANT
VALUES OVER SOUTHERN MENOMINEE AND SOUTHEAST DELTA COUNTIES TODAY.
HAVE A FEELING THAT THE STRUGGLE TO PUT OUT ANY DECENT QPF IS
RELATED TO THE LOW LEVEL SHEAR INDICATED BY THE MODELS. THIS CAN BE
SEEN AT THE PRESENT TIME IN EAST CENTRAL WISCONSIN WHERE WINDS ARE
PREDOMINATELY EASTERLY IN THE LOWER LEVELS AND LAKE ENHANCEMENT IS
OCCURRING. BUT FARTHER NORTH ACROSS THE BAY OF GREEN BAY...THE DRIER
AIR COMBINED WITH WINDS VARYING IN DIRECTION DEPENDING ON LEVEL
(850MB VEERING SOUTHEAST...925MB STAYING MAINLY EASTERLY...AND
SURFACE WINDS NORTHEASTERLY) HAS BEEN LIMITING DEVELOPMENT THUS
FAR. THIS WILL LIKELY CONTINUE THROUGH THE AFTERNOON UNTIL THE
TROUGH DEVELOPS ACROSS THE AREA AND FOCUSES WINDS OUT OF THE
SOUTHEASTERLY DIRECTION THIS EVENING. AM WONDERING IF THIS SHEAR
WILL BE ENOUGH TO LIMIT ANY REAL STRONG LAKE ENHANCED BANDS. IN
ADDITION...INVERSION HEIGHTS AROUND MENOMINEE THIS MORNING ARE
AROUND 5-6KFT AND REMAINS THROUGH MUCH OF TODAY...LIKELY LIMITING
STRONG ENHANCEMENT AND HIGHER TOTALS. THEY ARE A LITTLE HIGHER
AROUND ESCANABA (6-7KFT THIS AFTERNOON/EVENING) AND WHEN COMBINED
WITH THE MORE UNIFORM FLOW THIS EVENING...THINK THAT IS WHEN THEY
WILL HAVE THE BEST OPPORTUNITY FOR MODERATE SNOWFALL. ON THE
POSITIVE SIDE...MUCH OF THE LAKE ENHANCED FORCING IS IN OR JUST
BELOW THE DGZ AND ALLOW FOR SNOW RATIOS TO BE HIGHER AND AROUND 20
TO 1. UNFORTUNATELY...DEALING WITH AROUND 20-1 SNOW RATIOS MAKES FOR
A DIFFICULT TIME ON PINNING DOWN AMOUNTS ON THESE LOWER END QPF
AMOUNTS. MODEL COBB SNOW AMOUNTS ARE ALL OVER THE BOARD WITH 12Z NAM
FOR KESC GIVING AROUND 3.5-4IN AND OUR LOCAL 00Z WRF-ARW HAS
3-3.8IN...WHILE THE 08Z RAP IS GIVING 1.3IN THROUGH 02Z. 03Z SREF
MEAN HAS 2.3-3.0 AND THINK THAT IS A REASONABLE COMPROMISE. AMOUNTS
FOR KMNM HAVE A SIMILAR RANGE...WITH THE HIGHEST AMOUNTS FROM THE
MODELS OF 4-5INCHES...BUT THOSE RUNS HAD 2IN OF ACCUMULATION ALREADY
EVEN THOUGH IT HASN/T EVEN STARTED SNOWING. THEREFORE...OPTED TO
LOWER AMOUNTS ABOUT AN INCH AND MAY NEED TO DO MORE IF THE SNOW
STRUGGLES TO DEVELOP THIS MORNING. STILL THINK THE HIGHEST AMOUNTS
WILL BE OVER THE GARDEN PENINSULA...WHERE AMOUNTS COULD REACH 5
INCHES.
OVERALL VERY UNCERTAIN ON SNOWFALL AMOUNTS FOR MENOMINEE AND DELTA
COUNTIES TODAY...LARGELY DUE TO THE LOW LEVEL SHEAR THAT LOOKS LIKE
IT WILL OCCUR. A LITTLE MORE CONFIDENCE IN PORTIONS OF DELTA AS
WINDS BECOME MORE FAVORABLE THIS EVENING AND THERE IS LESS
SHEAR...BUT EVEN THEN THE BANDS WILL LIKELY BE MOVING ENOUGH TO THE
EAST TO LIMIT SIGNIFICANT ACCUMULATIONS. THEREFORE...WILL KEEP THE
ADVISORY GOING FOR NOW (WITH WEAKER WORDING AND GREATER RANGE IN
TOTALS TO SHOW UNCERTAINTY) SINCE THEY SHOULD SEE SOME SNOW AND
ALLOW THE DAY SHIFT TO ASSESS THE SITUATION THROUGH THE MORNING.
WITH THE UNCERTAINTY...DID NOT EXPAND ADVISORY TO SOUTHERN
SCHOOLCRAFT FOR TONIGHT EVEN THOUGH THERE TOTALS ARE IN THE SAME
RANGE AS SOUTHERN DELTA COUNTY.
A SURFACE LOW LOOKS TO DEVELOP ALONG THE SURFACE TROUGH OVER
NORTHERN LAKE SUPERIOR TONIGHT AS A SECONDARY AND STRONGER
SHORTWAVE DROPS OVER LAKE SUPERIOR. THE FLOW AROUND THE LOW WILL
KEEP MUCH OF THE LAKE EFFECT AWAY FROM THE LAKE SUPERIOR SHORELINES
THIS EVENING...BEFORE WINDS SHIFT TO THE WEST-NORTHWEST OVER THE
WESTERN LAKE OVERNIGHT WITH THE LOW MOVING INTO THE EASTERN LAKE.
THEREFORE...SHOULD SEE LAKE EFFECT INCREASING OVER THE WESTERN HALF
OF THE CWA OVERNIGHT WITH THAT WINDSHIFT AND THE INTENSIFYING LOW
OVER THE NORTHERN/EASTERN LAKE. INVERSION HEIGHTS DO LOOK TO IMPROVE
TO AROUND 10KFT OVER THE WESTERN LAKE OVERNIGHT AND WITH THE HELP OF
THE ADDITIONAL MOISTENING TODAY FROM THE SURFACE TROUGH...THAT AREA
SHOULD BE ABLE TO REALIZE THOSE FAIRLY HIGH INVERSION HEIGHTS.
850MB TEMPS FALL FROM -16C AT 06Z TO -20C BY 12Z SUNDAY...SO LAKE
INSTABILITY IS PRESENT AND BUFKIT SOUNDINGS ARE SHOWING LAKE INDUCED
CAPES IN THE 400-600 J/KG RANGE. IN ADDITION...THE EXTRA
FORCING FROM THE SHORTWAVE (INCREASING MID LEVEL Q-VECTOR
CONVERGENCE) WILL PRODUCE A CONDUCIVE PERIOD FOR LAKE EFFECT
SNOWFALL. THUS...WOULD EXPECT THERE TO BE A FAIRLY DECENT BURST OF
SNOW AFTER ABOUT 06Z FROM THE PORKIES UP THROUGH THE KEWEENAW
PENINSULA AS THE WINDS SHIFT TO THE WNW. HIGH RESOLUTION MODELS
AGREE FAIRLY WELL WITH THIS TIMING AND WILL BUMP POPS UP TO 100
PERCENT IN THOSE AREAS OVERNIGHT. WITH MUCH OF THE FORCING RIGHT
WITHIN AND A LITTLE ABOVE THE DGZ...SHOULD SEE FAIRLY DECENT SNOW
RATIOS (AROUND 20-22 TO 1) AND WOULD EXPECT AT LEAST OF COUPLE HOUR
PERIOD OF 1 IN/HR SNOWFALL AFTER 06Z IN SOME LOCATIONS.
THEREFORE...HAVE TRENDED THE SNOWFALL FORECAST UP A LITTLE BIT WITH
A GENERAL 1-3 INCH AMOUNTS AND HAVE THE HIGHEST VALUES OVER THE
HIGHER TERRAIN FROM THE PORKIES THROUGH THE KEWEENAW.
OVER THE REST OF THE CWA...WINDS WILL BE SHIFTING FROM
SOUTH-SOUTHEAST TO WESTERLY AS THE LOW MOVES TO THE EAST THROUGH
THE NIGHT. EXPECT THE ONGOING LAKE EFFECT OFF LAKE MICHIGAN TO
FOLLOW THAT EASTWARD PUSH THROUGH THE NIGHT AND LARGELY INFLUENCING
DELTA COUNTY IN THE EVENING AND THEN SCHOOLCRAFT AND SOUTHERN LUCE
COUNTIES DURING THE OVERNIGHT HOURS. THE EXPECTED EASTWARD MOVEMENT
OF THE LAKE ENHANCED SNOWFALL SHOULD LIMIT THE SNOWFALL AMOUNTS OVER
MOST OF THOSE AREAS TO A QUICK 1-3IN OF SNOW TONIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 403 AM EST SAT DEC 14 2013
NAM SHOWS A CLOSED 500 MB LOW NORTH OF LAKE SUPERIOR 12Z SUN WHICH
MOVES SOUTHEAST ON SUN. ANOTHER UPPER TROUGH DIGS SOUTHEAST INTO THE
AREA FOR MON NIGHT. NAM SHOWS SOME 850-500 MB Q-VECTOR CONVERGENCE
12Z MON MOVING INTO THE AREA WITH SOME DEEPER MOISTURE WHICH REMAINS
INTO MON NIGHT. LAKE EFFECT SNOW WILL CONTINUE THIS PERIOD FOR
SUNDAY INTO SUNDAY EVENING WITH COLD AIR IN NORTHWEST AND NORTH LAKE
EFFECT SNOW BELTS. ON MONDAY...THERE COULD BE SOME LAKE ENHANCEMENT
MON AFTERNOON AND EVENING OFF OF LAKE MICHIGAN AND HAVE THIS COVERED
WITH LIKELY POPS IN THE EASTERN CWA FOR SOUTHWEST WIND FLOW. HAVE
LIKELY POPS MON NIGHT ACROSS THE KEWEENAW FOR WEST FLOW LAKE EFFECT
SNOW BELTS. DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST FOR
TEMPERATURES.
IN THE EXTENDED...GFS AND ECMWF SHOW A BROAD 500 MB TROUGH OVER THE
CENTRAL AND EASTERN U.S. 12Z TUE. THIS TROUGH PULLS EAST 12Z WED
WITH SFC HIGH PRESSURE ALONG THE MISSISSIPPI RIVER VALLEY. SFC LOW
PRESSURE MOVES INTO THE CENTRAL PLAINS 12Z THU. GFS AND ECMWF SHOW A
500 MB TROUGH OVER THE NORTHERN PLAINS AND DESERT SW 12Z FRI. COLDER
THAN NORMAL TEMPERATURES LOOK TO CONTINUE THIS FORECAST PERIOD
EXCEPT FOR A BRIEF RESPITE ON THU INTO FRIDAY BEFORE COLD AIR
ARRIVES AGAIN. STILL LOOKS COLD ENOUGH WITH A WARM FRONT TO THE
SOUTH AND WARM AIR JUST TO THE SOUTH TO KEEP THE PCPN AS SNOW ON
THU...BUT WILL HAVE TO WATCH THIS AS THERE IS A LOW POSSIBILITY OF
SOME MIXED PCPN IN THE FAR SOUTH. BASICALLY...LAKE EFFECT SNOW WILL
CONTINUE THROUGH WED BEFORE SYSTEM KICKS OUT ON THU. COLD AIR THEN
ARRIVES AGAIN LATE ON FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1235 AM EST SAT DEC 14 2013
CMX...EXPECT PREDOMINANT VFR CONDITIONS UNTIL ABOUT SUNRISE...WHEN
THE VEERING LLVL WINDS ON THE SRN FLANK OF HI PRES MOVING ACRS
ONTARIO SHIFT TO THE E AND POSSIBLY ALLOW MORE -SHSN/MVFR CONDITIONS
TO IMPACT THIS LOCATION. AS THE FLOW CONTINUES TO VEER TO THE SE AND
THEN S...ANY LES SHOULD SHIFT TO THE N OF CMX BY LATE MRNG. THERE
MAY BE SOME -SN AS A DISTURBANCE APRCHS FM THE NW...BUT DOWNSLOPE
FLOW SHOULD RESULT IN VFR CONDITIONS. THE CLOSER APRCH OF SFC LO
PRES AND ATTENDANT COLD FNT LATE IN THE PERIOD MAY BRING A RETURN OF
HEAVIER SHSN/MVFR TO PERHAPS IFR CONDITIONS.
IWD...WITH DRY AND DOWNSLOPE E WIND VEERING TO THE S THRU THIS
PERIOD...VFR CONDITIONS SHOULD DOMINATE. SOME -SN MAY DEVELOP ON
SAT...BUT DOWNSLOPE NATURE OF THE PREVAILING FLOW SHOULD KEEP THE
LLVLS DRY ENUF FOR VFR CIGS/VSBYS. THE PASSAGE OF A COLD FNT AND
WSHFT TO THE WNW THIS EVNG WL BRING MORE SHSN/MVFR TO PERHAPS IFR
CONDITIONS.
SAW...EXPECT ANY LINGERING -SHSN TO SHIFT TO THE N OF SAW BY 06Z AS
THE LLVL FLOW VEERS TOWARD THE E. THEN WITH RELATIVELY DRY E TO SE
FLOW...VFR WX SHOULD THEN PREVAIL THRU THIS MRNG. SOME -SN IS LIKELY
TO DVLP ON SAT AFTN...AND SSE FLOW UPSLOPING OFF LK MI WL BRING
ABOUT MVFR CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 503 AM EST SAT DEC 14 2013
HIGH PRESSURE OVER SOUTHERN ONTARIO EARLY THIS MORNING WILL MOVE
EAST INTO SOUTHWEST QUEBEC TODAY WHILE A LOW PRESSURE SYSTEM TAKING
SHAPE IN THE LOWER MISSISSIPPI VALLEY MOVES INTO THE MID ATLANTIC
STATES. WHILE THIS OCCURS...A LOW PRESSURE TROUGH WILL SETUP OVER
THE UPPER GREAT LAKES THIS AFTERNOON AND THEN DEVELOP INTO A WEAK
LOW TONIGHT BEFORE SHIFTING SOUTHEAST SUNDAY AFTERNOON INTO SUNDAY
NIGHT. EXPECT GENERALLY LIGHT WINDS ALONG THIS TROUGH TODAY AND
TONIGHT...BUT DO EXPECT THEM TO INCREASE OUT OF THE NORTHWEST ON
SUNDAY...WITH GUSTS TO 30KTS EXPECTED SUNDAY AFTERNOON/EVENING.
WINDS WILL QUICKLY DIMINISH LATE SUNDAY NIGHT BEFORE INCREASING OUT
OF THE SOUTHWEST ON MONDAY (GUSTS TO 30KTS) AHEAD OF A CLIPPER LIKE
LOW MOVING SOUTHEAST THROUGH SOUTHERN CANADA AND BRUSHING THE UPPER
GREAT LAKES ON MONDAY NIGHT AND TUESDAY. AS THE COLD FRONT SWEEPS
THROUGH ON MONDAY NIGHT...EXPECT WINDS TO SHIFT TO THE NORTHWEST
AND BE IN THE 20-30KT RANGE. THERE COULD EVEN BE SOME GALE FORCE
GUSTS TO 35KTS TUESDAY INTO TUESDAY NIGHT. ANOTHER QUICK HIGH
PRESSURE RIDGE WILL MOVE IN ON WEDNESDAY AND DIMINISH WINDS AHEAD
OF LOW DEVELOPING IN THE CENTRAL PLAINS AND EXPECTED TO MOVE
THROUGH THE GREAT LAKES REGION ON THURSDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY FROM 9 AM THIS MORNING TO 1 AM EST
SUNDAY FOR MIZ013.
LAKE EFFECT SNOW ADVISORY UNTIL 8 PM CST THIS EVENING FOR MIZ012.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...07
AVIATION...KC
MARINE...SRF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
338 PM CST SAT DEC 14 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 338 PM CST SAT DEC 14 2013
LIGHT SNOW CONTINUED ACROSS THE REGION TODAY AHEAD OF A WEAK
SHORTWAVE THAT WAS EMBEDDED IN THE PERSISTENT NORTHWEST FLOW.
FORECAST SOUNDINGS OFF THE RAP SHOWED A BEAUTIFUL VEERING
PROFILE...WITH DENDRITIC SATURATION FROM THE SURFACE UP TO 650MB.
THE REGION OF ASCENT ROOTED IN THE POSITIVE VORTICITY ADVECTION
ASSOCIATED WITH THE CURVATURE OF THIS WAVE WILL CONTINUE TO SHIFT
EASTWARD OVERNIGHT. MODEST H500 HEIGHT RISES AND AN ASSOCIATED
SURFACE RIDGE OF HIGH PRESSURE WILL BUILD OVER WESTERN MN...WHICH
WILL SET THE STAGE FOR ANOTHER NIGHT OF COLD TEMPERATURES WITH LIGHT
WINDS...ESPECIALLY IF SKIES MANAGE TO CLEAR. HOWEVER...DESPITE THE
SURFACE HIGH...CONFIDENCE IN CLEARING SKIES IS LOW AS AGITATED
NORTHWEST FLOW WILL CONTINUE. THE THERMAL PROFILE FROM FORECAST
SOUNDINGS ARE SUCH THAT ONLY A SMALL AMOUNT OF UPWARD VERTICAL
MOTION IS REQUIRED TO PRODUCE A FEW SNOWFLAKES...LET ALONE MID LEVEL
CLOUDS. IN FACT...THE NEXT UPPER LEVEL WAVE / LOW LEVEL WARM AIR
ADVECTION DUO WILL MOVE ACROSS WESTERN MN ON SUNDAY...SO HAVE
INCREASED POPS CONSIDERABLY SINCE CONFIDENCE IS HIGH IN ANOTHER
ROUND OF LIGHT SNOWFALL ALONG THE MINNESOTA RIVER VALLEY. SUNDAYS
HIGH TEMPERATURES WILL STRUGGLE TO GET OUT OF THE SINGLE DIGITS FOR
MOST LOCATIONS.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 338 PM CST SAT DEC 14 2013
THE UPPER WAVE BRINGING LIGHT SNOW SUNDAY WILL SLIDE SOUTHEAST
INTO THE OHIO VALLEY SUNDAY NIGHT WHILE ANOTHER WAVE DIVES
SOUTHEAST INTO NORTHERN MINNESOTA EARLY MONDAY MORNING. A QUICK
SHOT OF DECENT ISENTROPIC UPGLIDE AND MODEST MOISTURE ADVECTION
WILL BE ENOUGH TO GENERATE A BAND OF SNOW ACROSS NORTHERN AND
CENTRAL MN WHICH WILL PROPAGATE INTO WESTERN WISCONSIN MONDAY
MORNING. ONE TO TWO INCHES OF SNOW ARE POSSIBLE BEFORE STRONG
ISENTROPIC DOWNGLIDE TAKES OVER AGAIN IN THE AFTERNOON AND MONDAY
NIGHT.
A TROUGH DIGGING INTO THE GREAT LAKES WILL CLIP THE FORECAST
AREA...LEAVING WESTERLY SURFACE FLOW IN PLACE THROUGH MIDWEEK.
MILD TEMPS /COMPARED TO THE REST OF THIS MONTH/ CAN BE
EXPECTED...ALTHOUGH TUESDAY NIGHT WILL BE COLD AS THE RIDGE
AXIS PASSES OVERHEAD.
EYES THEN TURN TO LATE WEEK AS A TROUGH DIGS DOWN THE WEST COAST
AND HIGH PRESSURE BUILDS SOUTHWARD INTO WESTERN AND CENTRAL
CANADA. FAST ZONAL FLOW WILL DEVELOP ALONG THE U.S./CANADIAN
BORDER WEDNESDAY WITH ONE WAVE RAPIDLY PUSHING EAST ACROSS
NORTHERN MINNESOTA. SENSIBLE WEATHER IMPACTS FOR OUR AREA WILL BE
MINIMAL INITIALLY WITH FORCING AND MOISTURE CONVERGENCE REMAINING
WELL NORTH. HOWEVER...THIS WAVE AND HIGH PRESSURE BUILDING TOWARD
THE NORTHERN PLAINS WILL PUSH A COLD FRONT SOUTH WEDNESDAY NIGHT.
AS SOME ENERGY ROUNDS THE BASE OF THE WESTERN TROUGH...A SURFACE
LOW WILL SPAWN OVER COLORADO THURSDAY AND TRACK EAST NORTHEAST
ACROSS THE PLAINS AND INTO THE LOWER GREAT LAKES LATE
THURSDAY/THURSDAY NIGHT. NORMALLY THIS WOULD BE A HIGHLY FAVORABLE
TRACK FOR HEAVY SNOWFALL ACROSS THE CWA. HOWEVER...GIVEN THE FAST
FLOW WITH TIGHTENING BAROCLINICITY LEADING TO A MORE PROGRESSIVE
FEATURE...IN CONJUNCTION WITH SURFACE RIDGING OVER THE GULF WHICH
WILL LIKELY DELAY THE NORTHERLY MOISTURE TRANSPORT UNTIL THE
SURFACE WAVE IS TO THE EAST OF THE AREA...WOULD LIMIT THE
POTENTIAL FOR A BIG SNOWFALL. IF MODELS EVOLVE THE WESTERN TROUGH
DIFFERENTLY...AND THEY MOST LIKELY WILL AT THIS RANGE...THIS
FORECAST CAN CERTAINLY CHANGE. LEFT POPS IN THE MID RANGE FOR NOW
WITH THE MOISTURE UNCERTAINTY AND SOME TIMING DIFFERENCES BETWEEN
THE MEDIUM RANGE MODELS.
THE HIGH WILL BUILD IN FOR FRIDAY AND SATURDAY WITH ANOTHER BLAST
OF ARCTIC AIR ACCOMPANYING IT. HIGHS WILL AGAIN BE IN THE SINGLE
DIGITS WITH LOWS FRIDAY NIGHT IN THE TEENS TO 20S BELOW ZERO.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1129 AM CST SAT DEC 14 2013
LIGHT SNOW WILL CONTINUE EASTWARD INTO WISCONSIN...WITH A FEW
FLURRIES LAGGING BEHIND. LIGHT WINDS WILL GRADUALLY BECOME
NORTHWESTERLY. CEILINGS REMAIN THE BIGGEST CHALLENGE...AND AFTER A
FEW BREAKS THIS AFTERNOON SHOULD SEE MVFR CLOUDS RETURN LATER
TONIGHT ACROSS THE NORTHERN SITES. TOMORROW LIGHT SNOW WILL
DEVELOP IN WESTERN MN AFFECTING KAXN AND KRWF.
KMSP...
VFR CONDITIONS SHOULD HOLD MOST OF THE AFTERNOON. A FEW BRIEF
REDUCTION IN VISBYS ARE POSSIBLE WITH LINGERING LIGHT SNOW
SHOWERS. CONFIDENCE IS LOW IN THE MVFR CEILING FORECAST FOR THIS
EVENING. TOMORROWS SNOW SHOULD BE WEST AND SOUTH OF THE
METRO...WITH ONLY MID LEVEL CLOUDS EXPECTED AT KMSP.
/OUTLOOK FOR KMSP/
MON...VFR/MVFR WITH IFR/-SN POSSIBLE. WINDS SW AT 10KTS.
TUE...VFR WITH MVFR/-SN POSSIBLE. WINDS W AT 10KTS.
WED...VFR. WINDS VRBL AT 05KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...JRB
LONG TERM...BORGHOFF
AVIATION...JRB
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1200 PM CST SAT DEC 14 2013
.UPDATE...
ISSUED AT 1155 AM CST SAT DEC 14 2013
UPDATED FOR AVIATION DISCUSSION.
UPDATE ISSUED AT 1017 AM CST SAT DEC 14 2013
LIGHT SNOW WAS FALLING ACROSS MOST OF THE NORTHLAND THIS
MORNING...WITH BANDS OF HEAVIER SNOWFALL OCCURRING FROM THE TWIN
PORTS NORTH ALONG THE NORTH SHORE. SPOTTERS AROUND LUTSEN AND
TOFTE HAVE HAD 3-4 INCHES SO FAR...WITH RATES OF 1 TO 1.5 INCHES
PER HOUR AT LUTSEN. CONDITIONS LOOK VERY FAVORABLE FOR PERIODS OF
HEAVIER SNOW BANDS FROM SILVER BAY THROUGH AT LEAST GRAND
MARAIS...SHIFTING AWAY FROM SILVER BAY EARLIER THIS AFTERNOON. WE
UPGRADED THE ADVISORY FOR COASTAL LAKE AND COOK COUNTIES TO A
WARNING WITH ADDITIONAL SNOWFALL OF 4 TO 7 INCHES...MAINLY BETWEEN
SILVER BAY AND GRAND MARAIS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 415 AM CST SAT DEC 14 2013
HAS BEEN QUITE A NIGHT IN TERMS OF LAKE EFFECT SNOW. RECEIVED A
REPORT A SHORT TIME AGO OF CLOSE TO A FOOT OF SNOW FROM A VERY
SMALL LAKE EFFECT SNOW BAND THAT PARKED OVER THE CITY OF SUPERIOR
FRIDAY EVENING. AFTER BEING IN ONE LOCATION FOR SEVERAL HOURS...IT
HAD BASICALLY STARTED ITS PROGRESSION ALONG THE NORTH SHORE BY
MIDNIGHT. THE HEAVIEST SNOW BAND WAS JUST NORTHEAST OF GOOSEBERRY
FALLS STATE PARK AS OF 4 AM. THE HIGH RESOLUTION MODELS ARE
GENERALLY IN AGREEMENT THAT THE BANDS WILL CONTINUE TO MEANDER
ACROSS THE NORTH SHORE OF LAKE SUPERIOR TODAY. THE HRRR SEEMS TO
HAVE A FAIRLY DECENT HANDLE ON THE CURRENT LOCATION OF THE
HEAVIEST SNOW BAND...WITH LOCALLY HEAVY SNOW ACROSS LAKE COUNTY
THROUGH THE MORNING. THE HRRR AND MOST OF THE OTHER MODELS THEN
MIGRATE THAT AREA OF HEAVIER SNOW INTO COOK COUNTY FOR THE
AFTERNOON. GOING TO CONTINUE THE LAKE EFFECT SNOW ADVISORY...WITH
LOCALIZED 5 TO 7 INCHES...BUT COULD POTENTIALLY SEE MORE THAN THAT
IF THE BANDS PARK OVER ONE LOCATION FOR TOO LONG. WILL HAVE TO
KEEP A CLOSE EYE ON IT TODAY.
MEANWHILE...LIGHT SNOW WILL PROGRESS ACROSS MUCH OF THE NORTHLAND
TODAY. AMOUNTS WILL GENERALLY BE LIGHT WITH 1 TO 2 INCHES FOR MOST
AREAS.
ARCTIC HIGH PRESSURE WILL THEN BUILD DOWN BEHIND THE DEPARTING
WEAK LOW PRESSURE SYSTEM TONIGHT. HAVE DROPPED TEMPS
CONSIDERABLY...ESPECIALLY ACROSS THE NORTH. COULD SEE SOME -20S
ESPECIALLY ACROSS THE NORTH.
HAVE ALSO DROPPED TEMPS A BIT FOR SUNDAY...AS IT APPEARS SOME
NORTHERN LOCATIONS MAY STRUGGLE TO REACH ZERO DESPITE PARTIAL
SUNSHINE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 415 AM CST SAT DEC 14 2013
FAST MOVING SHORTWAVE WILL MOVE ACROSS THE CWA EARLY IN THE PERIOD
WITH A PERIOD OF LIGHT SNOW OCCURRING LATE SUNDAY NIGHT INTO EARLY
TUESDAY. BEYOND THAT THE UPPER JET WILL STRETCH ACROSS THE REGION
THROUGH EARLY THURSDAY. WITHIN THAT TIME PASSING SNOW SHOWERS ARE
POSSIBLE...MAINLY OVER THE NRN AND ERN CWA. ALL MED RANGE MDLS
SUPPORT THE MOVEMENT OF ANOTHER MID LVL TROF OVER THE REGION
THUR/FRI. POPS INCREASE LATE IN THE WEEK HOWEVER DOMINANT NRN BRANCH
OF UPPER JET WILL KEEP ANY SIGNIFICANT SFC DEVELOPMENT SOUTH AND
EAST OF THE AREA. TEMPS WILL MODERATE TO SOME EXTENT DURING THE EARLY
WEEK ESPECIALLY OVER THE SOUTH AND WEST AS FAST FLOW ALOFT KEEPS ANY
REINFORCING ARCTIC AIR FOCUSED JUST NORTH OF THE REGION ACROSS SRN
CANADA. LATE IN THE WEEK A DEVELOPING SFC LOW WILL MOVE FROM THE
PLAINS INTO THE LOWER GT LAKES. THIS SYSTEM WILL PULL ANOTHER SURGE
OF COLDER AIR SOUTH FOR THE WEEKEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1155 AM CST SAT DEC 14 2013
VARIABLE CIGS THIS AFTERNOON AND THIS EVENING WITH IMPROVING VSBYS
IN LIGHT TO MDT SNOW SHOWERS. CIGS SHOULD BECOME DOMINANTLY MVFR
THIS EVENING AND TONIGHT...WITH LOW CLOUDS BREAKING UP SUNDAY
MORNING. LIGHT SW WINDS WILL SHIFT TO THE NW TONIGHT AND GUST 10
TO 20 KT IN THE LATE EVENING AND OVERNIGHT HOURS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 11 -11 1 -7 / 100 30 10 30
INL 3 -21 -3 -10 / 100 10 10 40
BRD 11 -13 3 -4 / 100 10 10 40
HYR 17 -8 4 -9 / 100 30 10 20
ASX 17 -1 8 -4 / 90 50 30 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...LAKE EFFECT SNOW ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ012.
LAKE EFFECT SNOW WARNING UNTIL 6 PM CST THIS EVENING FOR MNZ020-
021.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...DAP
LONG TERM...CANNON
AVIATION...BJT
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1140 AM CST SAT DEC 14 2013
.UPDATED FOR 18Z AVIATION DISCUSSION...
ISSUED AT 1129 AM CST SAT DEC 14 2013
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 312 AM CST SAT DEC 14 2013
YET ANOTHER PROLONGED LIGHT SNOW EVENT IS ONGOING ACROSS THE AREA
THIS MORNING. FORCING FOR THIS IS RATHER WEAK AND BEST EVIDENCE
OF THIS IS PROBABLY THE FACT THAT A QUICK WALK OUTSIDE AT 230 AM
THIS MORNING REVEALED THAT THE MOON WAS STILL VISIBLE THROUGH ALL
THE SNOW AND CLOUDS! THE UPPER WAVE RESPONSIBLE FOR THE SNOW SHOWS
UP WELL WITH A PLOT OF POTENTIAL VORT OFF THE RAP AT H4 WHICH HAS
SHOWN A WEAK ANOMALY STEADILY PUSHING EAST ACROSS THE DAKOTAS THIS
MORNING. THIS PV FEATURE AS ALSO BEEN AIDED BY WEAK DIFFLUENCE
ALOFT WITHIN THE RIGHT ENTRANCE OF AN UPPER JET THE STRETCHES FROM
CENTRAL MN OVER TO NEW ENGLAND. SNOW REPORTS FALL OFF QUICKLY WEST
OF THE PV FEATURE OVER THE DAKOTAS...AND EXPECT THIS TREND TO
CONTINUE AS THIS WAVE WORKS ACROSS THE AREA TODAY. HRRR TIMING FOR
WORKING THE BACK EDGE OF THE SNOW ACROSS THE AREA MATCHES UP
FAIRLY WELL WITH THE RAPS TIMING OF THE PV FEATURE ACROSS THE
AREA...SO LET THE HRRR REFLECTIVITY FORECAST GUIDE POPS FOR TODAY.
THIS RESULTED IN A SLIGHT SLOWING OF THE POP DECREASE FROM WEST TO
EAST THAT WILL START AROUND 12Z OUT BY THE SODAK BORDER. THIS
SYSTEM WILL QUICKLY MOVE OUT OF THE EASTERN CWA THIS
EVENING...WITH TONIGHT EXPECTED TO BE MAINLY SNOW FREE. THE ONLY
POTENTIAL EXCEPTION TO THIS WILL BE LATE TONIGHT OUT IN FAR
WESTERN MN AS NEXT SHIELD OF WAA PRECIP WILL BE MOVING ACROSS THE
DAKOTAS...THOUGH BETTER PRECIP CHANCES WITH THIS LOOK TO ARRIVE
SUNDAY MORNING.
FOR CURRENT SNOW...CONTINUED TREND OF FAIRLY WIDESPREAD 1-2 INCHES
OF SNOW ACROSS THE ENTIRE AREA. ALL MODELS FROM THE HRRR AND
HOPWRF TO THE ECMWF/GFS SHOW FAIRLY WIDESPREAD TOTAL QPF AMOUNTS
BETWEEN 0.05 AND 0.10 INCHES...WHICH SHOULD BE ABLE TO TRANSLATE
INTO THE 1-2 INCH RANGE. THOUGH BUFKIT THERMAL PROFILES WITH THEIR
DEEP DENDRITIC GROWTH ZONES WOULD SUGGEST SEEING SNOW RATIOS IN
EXCESS OF 20:1...WEAK NATURE OF FORCING HAS PREVENTED ICE CRYSTAL
GROWTH FROM GETTING OUT OF HAND...KEEPING SNOW TYPE AS MAINLY FINE
CRYSTALS. HENCE WHY 12-15 HOURS OF LIGHT SNOW IS ONLY EXPECTED TO
NET 1 TO 2 INCHES OF ACCUMULATIONS.
FOR TEMPERATURES...TODAY WILL BE SIMILAR TO FRIDAY AS CLOUDS
COMBINED WITH NORTH WINDS BRINGING DOWN THE ARCTIC AIR THAT IS
SITTING UP IN NRN MN HELPING TO LIMIT DIURNAL RANGES TODAY TO 5
DEGREES OR LESS. TONIGHT...THE ARCTIC AIR WILL FINALLY BE PUSHING
INTO THE MPX AREA...WHICH SHOULD ALLOW JUST ABOUT EVERYONE TO DIP
BELOW ZERO. TRENDED FORECAST LOWS TONIGHT TOWARD BIAS CORRECTED
VERSIONS OF THE ECMWF AND MET...WHICH RESULTED IN KNOCKING CLOSE 5
DEGREES OFF OF THE EXISTING FORECAST. IF WE CAN GET SKIES TO CLEAR
OUT...THEN TEMPS COULD GET COLDER STILL...ESPECIALLY OVER CENTRAL
MN WHERE LOWS IN THE -20S BELOW ZERO WOULD NOT BE OUT OF QUESTION.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 312 AM CST SAT DEC 14 2013
COLD NW FLOW WILL PERSIST ON THE BACKSIDE OF THE POTENT ERN
SEABOARD STORM OR SUN INTO MON AS RIDGING DEVELOPS OVER THE W
COAST. WHILE SFC HIGH PRES OVER S-CENTRAL CANADA...EXTENDING SWD
INTO THE DAKOTAS AND MN/WI...SEVERAL WAVES DRIVING SEWD WITHIN THE
FLOW ALOFT WILL ENCOUNTER ENHANCED H7-H5 LIFT AND A SWATH OF
RELATIVELY DEEPER MOISTURE. THIS COMBINATION WILL PRODUCE LIGHT
SNOW FOR SUN INTO MON. THOUGH WAA WILL COMMENCE DURG THE DAY ON
MON...THIS WAVE LOOKS TO EXIT THE REGION FAST ENOUGH SUCH THAT ANY
AND ALL PRECIP FROM IT SHALL REMAIN AS ALL -SN. SNOWFALL
ACCUMULATIONS WILL GENERALLY RANGE 1-2 INCHES...THOUGH IT IS
POSSIBLE THAT FAR ERN PORTIONS OF THE MPX CWFA /SPECIFICALLY...A
FEW WRN WI COUNTIES/ MAY RECEIVE UPWARDS OF 3-4 INCHES. STILL A
LITTLE BIT OF TIME TO IRON OUT THESE DETAILS.
MORE EXTENSIVE HIGH PRES WITH WARMER TEMPERATURES WILL CROSS THE
REGION TUE INTO WED...RESULTING IN HIGHER H5 HEIGHTS PRODUCING MAX
TEMPS INTO THE LOW-MID 20S WITH NO PRECIP EXPECTED.
ATTENTION THEN STILL IS FOCUSED ON THE END OF THE WEEK DUE TO THE
DEVELOPMENT OF A POTENT STORM SYSTEM DEVELOPING IN THE LEE OF THE
ROCKIES. AIDING THE DEVELOPMENT WILL BE THE WRN CONUS RIDGE
SHIFTING ACRS THE COUNTRY...PLACING THE SRN JET OVER THE
CYCLOGENESIS REGION AND ALLOWING A TRACK FOR IT TO MOVE NE. THERE
IS STILL MUCH UNCERTAINTY WITH REGARDS TO THE TRACK AND THE AMOUNT
OF WARM AIR ENTRAINED WITHIN THE SYSTEM. ATTM...THE TRACK OF THE
LOW PRES CENTER REMAINS S OF THE MPX CWFA...WHICH WOULD INDICATE
THAT THE PREVAILING P-TYPE IS -SN. HAVE ADVERTISED AS SUCH
ALTHOUGH THERE IS THE CAVEAT THAT IF THE TRACK SHIFTS FURTHER
N...THEN MULTIPLE P-TYPES MAY WELL BE INTRODUCED IN LATER
FORECASTS. THE SYSTEM DOES LOOK TO BE RATHER QUICK... TRACKING
FROM THE CO REGION NEWD INTO THE GREAT LAKES IN ABOUT 24 HRS. WITH
DEEP LONGWAVE TROUGHING AIDING ITS MOVEMENT...THE PRONOUNCED NW
FLOW BEHIND THIS SYSTEM WILL BRING DOWN ANOTHER ROUND OF ARCTIC
AIR STARTING THU NIGHT AND LASTING NOT ONLY FRIDAY BUT ALSO INTO
THE WEEKEND. SO...ALTHOUGH THERE IS LITTLE CONFIDENCE IN THE
DETAILS...THE OVERALL SCENARIO OF SEEING A POTENT WINTER STORM
FOLLOWED BY MUCH COLDER AIR IS LOOKING MORE REALISTIC BY THE MODEL
RUN.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1129 AM CST SAT DEC 14 2013
LIGHT SNOW WILL CONTINUE EASTWARD INTO WISCONSIN...WITH A FEW
FLURRIES LAGGING BEHIND. LIGHT WINDS WILL GRADUALLY BECOME
NORTHWESTERLY. CEILINGS REMAIN THE BIGGEST CHALLENGE...AND AFTER A
FEW BREAKS THIS AFTERNOON SHOULD SEE MVFR CLOUDS RETURN LATER
TONIGHT ACROSS THE NORTHERN SITES. TOMORROW LIGHT SNOW WILL
DEVELOP IN WESTERN MN AFFECTING KAXN AND KRWF.
KMSP...
VFR CONDITIONS SHOULD HOLD MOST OF THE AFTERNOON. A FEW BRIEF
REDUCTION IN VISBYS ARE POSSIBLE WITH LINGERING LIGHT SNOW
SHOWERS. CONFIDENCE IS LOW IN THE MVFR CEILING FORECAST FOR THIS
EVENING. TOMORROWS SNOW SHOULD BE WEST AND SOUTH OF THE
METRO...WITH ONLY MID LEVEL CLOUDS EXPECTED AT KMSP.
/OUTLOOK FOR KMSP/
MON...VFR/MVFR WITH IFR/-SN POSSIBLE. WINDS SW AT 10KTS.
TUE...VFR WITH MVFR/-SN POSSIBLE. WINDS W AT 10KTS.
WED...VFR. WINDS VRBL AT 05KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...MPG
LONG TERM...JPC
AVIATION...JRB
AREA FORECAST DISCUSSION
NWS DULUTH MN
1018 AM CST SAT DEC 14 2013
.UPDATE...
ISSUED AT 1017 AM CST SAT DEC 14 2013
LIGHT SNOW WAS FALLING ACROSS MOST OF THE NORTHLAND THIS
MORNING...WITH BANDS OF HEAVIER SNOWFALL OCCURRING FROM THE TWIN
PORTS NORTH ALONG THE NORTH SHORE. SPOTTERS AROUND LUTSEN AND
TOFTE HAVE HAD 3-4 INCHES SO FAR...WITH RATES OF 1 TO 1.5 INCHES
PER HOUR AT LUTSEN. CONDITIONS LOOK VERY FAVORABLE FOR PERIODS OF
HEAVIER SNOW BANDS FROM SILVER BAY THROUGH AT LEAST GRAND
MARAIS...SHIFTING AWAY FROM SILVER BAY EARLIER THIS AFTERNOON. WE
UPGRADED THE ADVISORY FOR COASTAL LAKE AND COOK COUNTIES TO A
WARNING WITH ADDITIONAL SNOWFALL OF 4 TO 7 INCHES...MAINLY BETWEEN
SILVER BAY AND GRAND MARAIS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 415 AM CST SAT DEC 14 2013
HAS BEEN QUITE A NIGHT IN TERMS OF LAKE EFFECT SNOW. RECEIVED A
REPORT A SHORT TIME AGO OF CLOSE TO A FOOT OF SNOW FROM A VERY
SMALL LAKE EFFECT SNOW BAND THAT PARKED OVER THE CITY OF SUPERIOR
FRIDAY EVENING. AFTER BEING IN ONE LOCATION FOR SEVERAL HOURS...IT
HAD BASICALLY STARTED ITS PROGRESSION ALONG THE NORTH SHORE BY
MIDNIGHT. THE HEAVIEST SNOW BAND WAS JUST NORTHEAST OF GOOSEBERRY
FALLS STATE PARK AS OF 4 AM. THE HIGH RESOLUTION MODELS ARE
GENERALLY IN AGREEMENT THAT THE BANDS WILL CONTINUE TO MEANDER
ACROSS THE NORTH SHORE OF LAKE SUPERIOR TODAY. THE HRRR SEEMS TO
HAVE A FAIRLY DECENT HANDLE ON THE CURRENT LOCATION OF THE
HEAVIEST SNOW BAND...WITH LOCALLY HEAVY SNOW ACROSS LAKE COUNTY
THROUGH THE MORNING. THE HRRR AND MOST OF THE OTHER MODELS THEN
MIGRATE THAT AREA OF HEAVIER SNOW INTO COOK COUNTY FOR THE
AFTERNOON. GOING TO CONTINUE THE LAKE EFFECT SNOW ADVISORY...WITH
LOCALIZED 5 TO 7 INCHES...BUT COULD POTENTIALLY SEE MORE THAN THAT
IF THE BANDS PARK OVER ONE LOCATION FOR TOO LONG. WILL HAVE TO
KEEP A CLOSE EYE ON IT TODAY.
MEANWHILE...LIGHT SNOW WILL PROGRESS ACROSS MUCH OF THE NORTHLAND
TODAY. AMOUNTS WILL GENERALLY BE LIGHT WITH 1 TO 2 INCHES FOR MOST
AREAS.
ARCTIC HIGH PRESSURE WILL THEN BUILD DOWN BEHIND THE DEPARTING
WEAK LOW PRESSURE SYSTEM TONIGHT. HAVE DROPPED TEMPS
CONSIDERABLY...ESPECIALLY ACROSS THE NORTH. COULD SEE SOME -20S
ESPECIALLY ACROSS THE NORTH.
HAVE ALSO DROPPED TEMPS A BIT FOR SUNDAY...AS IT APPEARS SOME
NORTHERN LOCATIONS MAY STRUGGLE TO REACH ZERO DESPITE PARTIAL
SUNSHINE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 415 AM CST SAT DEC 14 2013
FAST MOVING SHORTWAVE WILL MOVE ACROSS THE CWA EARLY IN THE PERIOD
WITH A PERIOD OF LIGHT SNOW OCCURRING LATE SUNDAY NIGHT INTO EARLY
TUESDAY. BEYOND THAT THE UPPER JET WILL STRETCH ACROSS THE REGION
THROUGH EARLY THURSDAY. WITHIN THAT TIME PASSING SNOW SHOWERS ARE
POSSIBLE...MAINLY OVER THE NRN AND ERN CWA. ALL MED RANGE MDLS
SUPPORT THE MOVEMENT OF ANOTHER MID LVL TROF OVER THE REGION
THUR/FRI. POPS INCREASE LATE IN THE WEEK HOWEVER DOMINANT NRN BRANCH
OF UPPER JET WILL KEEP ANY SIGNIFICANT SFC DEVELOPMENT SOUTH AND
EAST OF THE AREA. TEMPS WILL MODERATE TO SOME EXTENT DURING THE EARLY
WEEK ESPECIALLY OVER THE SOUTH AND WEST AS FAST FLOW ALOFT KEEPS ANY
REINFORCING ARCTIC AIR FOCUSED JUST NORTH OF THE REGION ACROSS SRN
CANADA. LATE IN THE WEEK A DEVELOPING SFC LOW WILL MOVE FROM THE
PLAINS INTO THE LOWER GT LAKES. THIS SYSTEM WILL PULL ANOTHER SURGE
OF COLDER AIR SOUTH FOR THE WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 551 AM CST SAT DEC 14 2013
LOW VFR/MVFR CEILINGS WILL TRANSITION TO MAINLY MVFR THIS MORNING
AS LIGHT SNOW CROSSES THE REGION. VISIBILITY MAY LOWER TO IFR AT
TIMES BUT CONFIDENCE NOT VERY HIGH AT THIS POINT. HIGHEST PROB OF
SNOW WILL BE THROUGH 00Z BEFORE INVERTED SFC TROUGH MOVES EAST AND
MOISTURE DECREASES. CYCLONIC MOIST FLOW WILL CONTINUE BEHIND
SYSTEM TONIGHT SO CLOUDS WILL BE SLOW TO DECREASE.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 11 -11 1 -7 / 100 30 10 30
INL 3 -21 -3 -10 / 100 10 10 40
BRD 11 -13 3 -4 / 100 10 10 40
HYR 17 -8 4 -9 / 100 30 10 20
ASX 17 -1 8 -4 / 90 50 30 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...LAKE EFFECT SNOW ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ012.
LAKE EFFECT SNOW WARNING UNTIL 6 PM CST THIS EVENING FOR MNZ020-
021.
WI...NONE.
LS...NONE.
&&
$$
UPDATE...MELDE
SHORT TERM...DAP
LONG TERM...CANNON
AVIATION...CANNON
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
630 AM CST SAT DEC 14 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 415 AM CST SAT DEC 14 2013
HAS BEEN QUITE A NIGHT IN TERMS OF LAKE EFFECT SNOW. RECEIVED A
REPORT A SHORT TIME AGO OF CLOSE TO A FOOT OF SNOW FROM A VERY
SMALL LAKE EFFECT SNOW BAND THAT PARKED OVER THE CITY OF SUPERIOR
FRIDAY EVENING. AFTER BEING IN ONE LOCATION FOR SEVERAL HOURS...IT
HAD BASICALLY STARTED ITS PROGRESSION ALONG THE NORTH SHORE BY
MIDNIGHT. THE HEAVIEST SNOW BAND WAS JUST NORTHEAST OF GOOSEBERRY
FALLS STATE PARK AS OF 4 AM. THE HIGH RESOLUTION MODELS ARE
GENERALLY IN AGREEMENT THAT THE BANDS WILL CONTINUE TO MEANDER
ACROSS THE NORTH SHORE OF LAKE SUPERIOR TODAY. THE HRRR SEEMS TO
HAVE A FAIRLY DECENT HANDLE ON THE CURRENT LOCATION OF THE
HEAVIEST SNOW BAND...WITH LOCALLY HEAVY SNOW ACROSS LAKE COUNTY
THROUGH THE MORNING. THE HRRR AND MOST OF THE OTHER MODELS THEN
MIGRATE THAT AREA OF HEAVIER SNOW INTO COOK COUNTY FOR THE
AFTERNOON. GOING TO CONTINUE THE LAKE EFFECT SNOW ADVISORY...WITH
LOCALIZED 5 TO 7 INCHES...BUT COULD POTENTIALLY SEE MORE THAN THAT
IF THE BANDS PARK OVER ONE LOCATION FOR TOO LONG. WILL HAVE TO
KEEP A CLOSE EYE ON IT TODAY.
MEANWHILE...LIGHT SNOW WILL PROGRESS ACROSS MUCH OF THE NORTHLAND
TODAY. AMOUNTS WILL GENERALLY BE LIGHT WITH 1 TO 2 INCHES FOR MOST
AREAS.
ARCTIC HIGH PRESSURE WILL THEN BUILD DOWN BEHIND THE DEPARTING
WEAK LOW PRESSURE SYSTEM TONIGHT. HAVE DROPPED TEMPS
CONSIDERABLY...ESPECIALLY ACROSS THE NORTH. COULD SEE SOME -20S
ESPECIALLY ACROSS THE NORTH.
HAVE ALSO DROPPED TEMPS A BIT FOR SUNDAY...AS IT APPEARS SOME
NORTHERN LOCATIONS MAY STRUGGLE TO REACH ZERO DESPITE PARTIAL
SUNSHINE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 415 AM CST SAT DEC 14 2013
FAST MOVING SHORTWAVE WILL MOVE ACROSS THE CWA EARLY IN THE PERIOD
WITH A PERIOD OF LIGHT SNOW OCCURRING LATE SUNDAY NIGHT INTO EARLY
TUESDAY. BEYOND THAT THE UPPER JET WILL STRETCH ACROSS THE REGION
THROUGH EARLY THURSDAY. WITHIN THAT TIME PASSING SNOW SHOWERS ARE
POSSIBLE...MAINLY OVER THE NRN AND ERN CWA. ALL MED RANGE MDLS
SUPPORT THE MOVEMENT OF ANOTHER MID LVL TROF OVER THE REGION
THUR/FRI. POPS INCREASE LATE IN THE WEEK HOWEVER DOMINANT NRN BRANCH
OF UPPER JET WILL KEEP ANY SIGNIFICANT SFC DEVELOPMENT SOUTH AND
EAST OF THE AREA. TEMPS WILL MODERATE TO SOME EXTENT DURING THE EARLY
WEEK ESPECIALLY OVER THE SOUTH AND WEST AS FAST FLOW ALOFT KEEPS ANY
REINFORCING ARCTIC AIR FOCUSED JUST NORTH OF THE REGION ACROSS SRN
CANADA. LATE IN THE WEEK A DEVELOPING SFC LOW WILL MOVE FROM THE
PLAINS INTO THE LOWER GT LAKES. THIS SYSTEM WILL PULL ANOTHER SURGE
OF COLDER AIR SOUTH FOR THE WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 551 AM CST SAT DEC 14 2013
LOW VFR/MVFR CEILINGS WILL TRANSITION TO MAINLY MVFR THIS MORNING
AS LIGHT SNOW CROSSES THE REGION. VISIBILITY MAY LOWER TO IFR AT
TIMES BUT CONFIDENCE NOT VERY HIGH AT THIS POINT. HIGHEST PROB OF
SNOW WILL BE THROUGH 00Z BEFORE INVERTED SFC TROUGH MOVES EAST AND
MOISTURE DECREASES. CYCLONIC MOIST FLOW WILL CONTINUE BEHIND
SYSTEM TONIGHT SO CLOUDS WILL BE SLOW TO DECREASE.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 11 -11 1 -7 / 70 30 10 30
INL 3 -21 -3 -10 / 70 10 10 40
BRD 11 -13 3 -4 / 80 10 10 40
HYR 17 -8 4 -9 / 80 30 10 20
ASX 17 -1 8 -4 / 60 50 30 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...LAKE EFFECT SNOW ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ012-
020-021.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...DAP
LONG TERM...CANNON
AVIATION...CANNON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
539 AM CST SAT DEC 14 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 312 AM CST SAT DEC 14 2013
YET ANOTHER PROLONGED LIGHT SNOW EVENT IS ONGOING ACROSS THE AREA
THIS MORNING. FORCING FOR THIS IS RATHER WEAK AND BEST EVIDENCE
OF THIS IS PROBABLY THE FACT THAT A QUICK WALK OUTSIDE AT 230 AM
THIS MORNING REVEALED THAT THE MOON WAS STILL VISIBLE THROUGH ALL
THE SNOW AND CLOUDS! THE UPPER WAVE RESPONSIBLE FOR THE SNOW SHOWS
UP WELL WITH A PLOT OF POTENTIAL VORT OFF THE RAP AT H4 WHICH HAS
SHOWN A WEAK ANOMALY STEADILY PUSHING EAST ACROSS THE DAKOTAS THIS
MORNING. THIS PV FEATURE AS ALSO BEEN AIDED BY WEAK DIFFLUENCE
ALOFT WITHIN THE RIGHT ENTRANCE OF AN UPPER JET THE STRETCHES FROM
CENTRAL MN OVER TO NEW ENGLAND. SNOW REPORTS FALL OFF QUICKLY WEST
OF THE PV FEATURE OVER THE DAKOTAS...AND EXPECT THIS TREND TO
CONTINUE AS THIS WAVE WORKS ACROSS THE AREA TODAY. HRRR TIMING FOR
WORKING THE BACK EDGE OF THE SNOW ACROSS THE AREA MATCHES UP
FAIRLY WELL WITH THE RAPS TIMING OF THE PV FEATURE ACROSS THE
AREA...SO LET THE HRRR REFLECTIVITY FORECAST GUIDE POPS FOR TODAY.
THIS RESULTED IN A SLIGHT SLOWING OF THE POP DECREASE FROM WEST TO
EAST THAT WILL START AROUND 12Z OUT BY THE SODAK BORDER. THIS
SYSTEM WILL QUICKLY MOVE OUT OF THE EASTERN CWA THIS
EVENING...WITH TONIGHT EXPECTED TO BE MAINLY SNOW FREE. THE ONLY
POTENTIAL EXCEPTION TO THIS WILL BE LATE TONIGHT OUT IN FAR
WESTERN MN AS NEXT SHIELD OF WAA PRECIP WILL BE MOVING ACROSS THE
DAKOTAS...THOUGH BETTER PRECIP CHANCES WITH THIS LOOK TO ARRIVE
SUNDAY MORNING.
FOR CURRENT SNOW...CONTINUED TREND OF FAIRLY WIDESPREAD 1-2 INCHES
OF SNOW ACROSS THE ENTIRE AREA. ALL MODELS FROM THE HRRR AND
HOPWRF TO THE ECMWF/GFS SHOW FAIRLY WIDESPREAD TOTAL QPF AMOUNTS
BETWEEN 0.05 AND 0.10 INCHES...WHICH SHOULD BE ABLE TO TRANSLATE
INTO THE 1-2 INCH RANGE. THOUGH BUFKIT THERMAL PROFILES WITH THEIR
DEEP DENDRITIC GROWTH ZONES WOULD SUGGEST SEEING SNOW RATIOS IN
EXCESS OF 20:1...WEAK NATURE OF FORCING HAS PREVENTED ICE CRYSTAL
GROWTH FROM GETTING OUT OF HAND...KEEPING SNOW TYPE AS MAINLY FINE
CRYSTALS. HENCE WHY 12-15 HOURS OF LIGHT SNOW IS ONLY EXPECTED TO
NET 1 TO 2 INCHES OF ACCUMULATIONS.
FOR TEMPERATURES...TODAY WILL BE SIMILAR TO FRIDAY AS CLOUDS
COMBINED WITH NORTH WINDS BRINGING DOWN THE ARCTIC AIR THAT IS
SITTING UP IN NRN MN HELPING TO LIMIT DIURNAL RANGES TODAY TO 5
DEGREES OR LESS. TONIGHT...THE ARCTIC AIR WILL FINALLY BE PUSHING
INTO THE MPX AREA...WHICH SHOULD ALLOW JUST ABOUT EVERYONE TO DIP
BELOW ZERO. TRENDED FORECAST LOWS TONIGHT TOWARD BIAS CORRECTED
VERSIONS OF THE ECMWF AND MET...WHICH RESULTED IN KNOCKING CLOSE 5
DEGREES OFF OF THE EXISTING FORECAST. IF WE CAN GET SKIES TO CLEAR
OUT...THEN TEMPS COULD GET COLDER STILL...ESPECIALLY OVER CENTRAL
MN WHERE LOWS IN THE -20S BELOW ZERO WOULD NOT BE OUT OF QUESTION.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 312 AM CST SAT DEC 14 2013
COLD NW FLOW WILL PERSIST ON THE BACKSIDE OF THE POTENT ERN
SEABOARD STORM OR SUN INTO MON AS RIDGING DEVELOPS OVER THE W
COAST. WHILE SFC HIGH PRES OVER S-CENTRAL CANADA...EXTENDING SWD
INTO THE DAKOTAS AND MN/WI...SEVERAL WAVES DRIVING SEWD WITHIN THE
FLOW ALOFT WILL ENCOUNTER ENHANCED H7-H5 LIFT AND A SWATH OF
RELATIVELY DEEPER MOISTURE. THIS COMBINATION WILL PRODUCE LIGHT
SNOW FOR SUN INTO MON. THOUGH WAA WILL COMMENCE DURG THE DAY ON
MON...THIS WAVE LOOKS TO EXIT THE REGION FAST ENOUGH SUCH THAT ANY
AND ALL PRECIP FROM IT SHALL REMAIN AS ALL -SN. SNOWFALL
ACCUMULATIONS WILL GENERALLY RANGE 1-2 INCHES...THOUGH IT IS
POSSIBLE THAT FAR ERN PORTIONS OF THE MPX CWFA /SPECIFICALLY...A
FEW WRN WI COUNTIES/ MAY RECEIVE UPWARDS OF 3-4 INCHES. STILL A
LITTLE BIT OF TIME TO IRON OUT THESE DETAILS.
MORE EXTENSIVE HIGH PRES WITH WARMER TEMPERATURES WILL CROSS THE
REGION TUE INTO WED...RESULTING IN HIGHER H5 HEIGHTS PRODUCING MAX
TEMPS INTO THE LOW-MID 20S WITH NO PRECIP EXPECTED.
ATTENTION THEN STILL IS FOCUSED ON THE END OF THE WEEK DUE TO THE
DEVELOPMENT OF A POTENT STORM SYSTEM DEVELOPING IN THE LEE OF THE
ROCKIES. AIDING THE DEVELOPMENT WILL BE THE WRN CONUS RIDGE
SHIFTING ACRS THE COUNTRY...PLACING THE SRN JET OVER THE
CYCLOGENESIS REGION AND ALLOWING A TRACK FOR IT TO MOVE NE. THERE
IS STILL MUCH UNCERTAINTY WITH REGARDS TO THE TRACK AND THE AMOUNT
OF WARM AIR ENTRAINED WITHIN THE SYSTEM. ATTM...THE TRACK OF THE
LOW PRES CENTER REMAINS S OF THE MPX CWFA...WHICH WOULD INDICATE
THAT THE PREVAILING P-TYPE IS -SN. HAVE ADVERTISED AS SUCH
ALTHOUGH THERE IS THE CAVEAT THAT IF THE TRACK SHIFTS FURTHER
N...THEN MULTIPLE P-TYPES MAY WELL BE INTRODUCED IN LATER
FORECASTS. THE SYSTEM DOES LOOK TO BE RATHER QUICK... TRACKING
FROM THE CO REGION NEWD INTO THE GREAT LAKES IN ABOUT 24 HRS. WITH
DEEP LONGWAVE TROUGHING AIDING ITS MOVEMENT...THE PRONOUNCED NW
FLOW BEHIND THIS SYSTEM WILL BRING DOWN ANOTHER ROUND OF ARCTIC
AIR STARTING THU NIGHT AND LASTING NOT ONLY FRIDAY BUT ALSO INTO
THE WEEKEND. SO...ALTHOUGH THERE IS LITTLE CONFIDENCE IN THE
DETAILS...THE OVERALL SCENARIO OF SEEING A POTENT WINTER STORM
FOLLOWED BY MUCH COLDER AIR IS LOOKING MORE REALISTIC BY THE MODEL
RUN.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 513 AM CST SAT DEC 14 2013
CLOUD TOPS BEGINNING TO WARM ACROSS WRN MN AS LIGHT SNOW THAT HAS
BEEN FALLING ALL NIGHT IS BEGINNING TO COME TO AN END OUT TO THE
WEST. EXISTING TAFS HAD A PRETTY GOOD HANDEL ON TIMING OF THE
DEPARTURE OF -SN...WITH ONLY MINOR TIMING REFINEMENTS MADE TO GET
TAFS MORE IN LINE WITH THE TIMING OF THE HRRR. CIG HEIGHTS ARE A
BIT MORE TRICKY AS CIGS HAVE BEEN TRENDING TOWARD VFR ACROSS THE
AREA AS THE -SN HAS BEGUN TO LIGHTEN UP. HOWEVER...EXTENSIVE MVFR
CIGS SIT ACROSS THE ERN DAKOTAS AND EXPECT THESE CIGS TO MOVE
BACK INTO THE AREA AS LOW LEVEL WINDS BECOME WRLY THIS MORNING
INTO THE AFTERNOON. IMPROVED CIGS TO START...WITH LOWER CONDITIONS
RETURNING LATE MORNING INTO THE AFTERNOON AS CLOUDS OVER THE
DAKOTAS WORK EAST. FOR TONIGHT...LOTS OF CLOUD COVER CAN BE FOUND
UPSTREAM INTO SRN CANADA...SO WE MAY MAINTAIN MOSTLY CLOUDY
CONDITIONS AS THE GFS SHOWS...THOUGH SAFELY IN THE VFR CATEGORY.
KMSP...LOWEST VSBYS ALL NIGHT ACROSS THE AREA WITH THE -SN HAVE
BEEN RIGHT OVER THE TWIN CITIES...AS MOST SURROUNDING SITES HAVE
MAINTAINED A 3-5SM VSBY WITH -SN. MAY SEE IFR VIS -SN CONTINUE
BEYOND 13Z...BUT THOSE KINDS OF VIS RESTRICTIONS SHOULD BE DONE BY
15Z. CIG FORECAST MAY BE OVERDONE TODAY AS CURRENT CHAOTIC STATE
OF CIG HEIGHTS DOES NOT HELP YIELD MUCH CONFIDENCE IN CIGS THROUGH
TODAY. AT THE VERY LEAST...HARD PRESSED AT THE MOMENT TO SEE CIGS
EVER DROPPING BELOW 018.
/OUTLOOK FOR KMSP/
SUN...MVFR CIGS PSBL. CHC OF -SN LATE. WINDS LGT AND VRB.
MON...MVFR CIGS PSBL. CHC OF -SN EARLY. WINDS SW 5-10 KTS.
TUE...VFR. WINDS WNW 10-15 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...MPG
LONG TERM...JPC
AVIATION...MPG
AREA FORECAST DISCUSSION
NWS DULUTH MN
416 AM CST SAT DEC 14 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 415 AM CST SAT DEC 14 2013
HAS BEEN QUITE A NIGHT IN TERMS OF LAKE EFFECT SNOW. RECEIVED A
REPORT A SHORT TIME AGO OF CLOSE TO A FOOT OF SNOW FROM A VERY
SMALL LAKE EFFECT SNOW BAND THAT PARKED OVER THE CITY OF SUPERIOR
FRIDAY EVENING. AFTER BEING IN ONE LOCATION FOR SEVERAL HOURS...IT
HAD BASICALLY STARTED ITS PROGRESSION ALONG THE NORTH SHORE BY
MIDNIGHT. THE HEAVIEST SNOW BAND WAS JUST NORTHEAST OF GOOSEBERRY
FALLS STATE PARK AS OF 4 AM. THE HIGH RESOLUTION MODELS ARE
GENERALLY IN AGREEMENT THAT THE BANDS WILL CONTINUE TO MEANDER
ACROSS THE NORTH SHORE OF LAKE SUPERIOR TODAY. THE HRRR SEEMS TO
HAVE A FAIRLY DECENT HANDLE ON THE CURRENT LOCATION OF THE
HEAVIEST SNOW BAND...WITH LOCALLY HEAVY SNOW ACROSS LAKE COUNTY
THROUGH THE MORNING. THE HRRR AND MOST OF THE OTHER MODELS THEN
MIGRATE THAT AREA OF HEAVIER SNOW INTO COOK COUNTY FOR THE
AFTERNOON. GOING TO CONTINUE THE LAKE EFFECT SNOW ADVISORY...WITH
LOCALIZED 5 TO 7 INCHES...BUT COULD POTENTIALLY SEE MORE THAN THAT
IF THE BANDS PARK OVER ONE LOCATION FOR TOO LONG. WILL HAVE TO
KEEP A CLOSE EYE ON IT TODAY.
MEANWHILE...LIGHT SNOW WILL PROGRESS ACROSS MUCH OF THE NORTHLAND
TODAY. AMOUNTS WILL GENERALLY BE LIGHT WITH 1 TO 2 INCHES FOR MOST
AREAS.
ARCTIC HIGH PRESSURE WILL THEN BUILD DOWN BEHIND THE DEPARTING
WEAK LOW PRESSURE SYSTEM TONIGHT. HAVE DROPPED TEMPS
CONSIDERABLY...ESPECIALLY ACROSS THE NORTH. COULD SEE SOME -20S
ESPECIALLY ACROSS THE NORTH.
HAVE ALSO DROPPED TEMPS A BIT FOR SUNDAY...AS IT APPEARS SOME
NORTHERN LOCATIONS MAY STRUGGLE TO REACH ZERO DESPITE PARTIAL
SUNSHINE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 415 AM CST SAT DEC 14 2013
FAST MOVING SHORTWAVE WILL MOVE ACROSS THE CWA EARLY IN THE PERIOD
WITH A PERIOD OF LIGHT SNOW OCCURRING LATE SUNDAY NIGHT INTO EARLY
TUESDAY. BEYOND THAT THE UPPER JET WILL STRETCH ACROSS THE REGION
THROUGH EARLY THURSDAY. WITHIN THAT TIME PASSING SNOW SHOWERS ARE
POSSIBLE...MAINLY OVER THE NRN AND ERN CWA. ALL MED RANGE MDLS
SUPPORT THE MOVEMENT OF ANOTHER MID LVL TROF OVER THE REGION
THUR/FRI. POPS INCREASE LATE IN THE WEEK HOWEVER DOMINANT NRN BRANCH
OF UPPER JET WILL KEEP ANY SIGNIFICANT SFC DEVELOPMENT SOUTH AND
EAST OF THE AREA. TEMPS WILL MODERATE TO SOME EXTENT DURING THE EARLY
WEEK ESPECIALLY OVER THE SOUTH AND WEST AS FAST FLOW ALOFT KEEPS ANY
REINFORCING ARCTIC AIR FOCUSED JUST NORTH OF THE REGION ACROSS SRN
CANADA. LATE IN THE WEEK A DEVELOPING SFC LOW WILL MOVE FROM THE
PLAINS INTO THE LOWER GT LAKES. THIS SYSTEM WILL PULL ANOTHER SURGE
OF COLDER AIR SOUTH FOR THE WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1225 AM CST SAT DEC 14 2013
SNOW OVERSPREADING AREA FROM THE WEST. CURRENTLY CONDITIONS VARY
FROM VFR TO MVFR...EXPECT THAT CIGS AND VSBYS WILL SLOWLY FALL TO
MVFR FOR MOST LOCATIONS. KDLH MAY ALSO FALL TO LIFR WITH THE LAKE
EFFECT SNOW BAND EXPECTED TO MOVE ACROSS THE TERMINAL IN THE NEXT
FEW HOURS. MVFR TO TEMPORARY IFR CONDITIONS IN LIGHT SNOW EXPECTED TO
PERSIST THROUGH APPROXIMATELY 21Z...BEFORE LIFTING TO MVFR CIGS
WITH VFR CIGS FOR THE EVENING.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 11 -11 1 -7 / 70 30 10 30
INL 3 -21 -3 -10 / 70 10 10 40
BRD 11 -13 3 -4 / 80 10 10 40
HYR 17 -8 4 -9 / 80 30 10 20
ASX 17 -1 8 -4 / 60 50 30 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...LAKE EFFECT SNOW ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ012-
020-021.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...DAP
LONG TERM...CANNON
AVIATION...CANNON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
413 AM CST SAT DEC 14 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 312 AM CST SAT DEC 14 2013
YET ANOTHER PROLONGED LIGHT SNOW EVENT IS ONGOING ACROSS THE AREA
THIS MORNING. FORCING FOR THIS IS RATHER WEAK AND BEST EVIDENCE
OF THIS IS PROBABLY THE FACT THAT A QUICK WALK OUTSIDE AT 230 AM
THIS MORNING REVEALED THAT THE MOON WAS STILL VISIBLE THROUGH ALL
THE SNOW AND CLOUDS! THE UPPER WAVE RESPONSIBLE FOR THE SNOW SHOWS
UP WELL WITH A PLOT OF POTENTIAL VORT OFF THE RAP AT H4 WHICH HAS
SHOWN A WEAK ANOMALY STEADILY PUSHING EAST ACROSS THE DAKOTAS THIS
MORNING. THIS PV FEATURE AS ALSO BEEN AIDED BY WEAK DIFFLUENCE
ALOFT WITHIN THE RIGHT ENTRANCE OF AN UPPER JET THE STRETCHES FROM
CENTRAL MN OVER TO NEW ENGLAND. SNOW REPORTS FALL OFF QUICKLY WEST
OF THE PV FEATURE OVER THE DAKOTAS...AND EXPECT THIS TREND TO
CONTINUE AS THIS WAVE WORKS ACROSS THE AREA TODAY. HRRR TIMING FOR
WORKING THE BACK EDGE OF THE SNOW ACROSS THE AREA MATCHES UP
FAIRLY WELL WITH THE RAPS TIMING OF THE PV FEATURE ACROSS THE
AREA...SO LET THE HRRR REFLECTIVITY FORECAST GUIDE POPS FOR TODAY.
THIS RESULTED IN A SLIGHT SLOWING OF THE POP DECREASE FROM WEST TO
EAST THAT WILL START AROUND 12Z OUT BY THE SODAK BORDER. THIS
SYSTEM WILL QUICKLY MOVE OUT OF THE EASTERN CWA THIS
EVENING...WITH TONIGHT EXPECTED TO BE MAINLY SNOW FREE. THE ONLY
POTENTIAL EXCEPTION TO THIS WILL BE LATE TONIGHT OUT IN FAR
WESTERN MN AS NEXT SHIELD OF WAA PRECIP WILL BE MOVING ACROSS THE
DAKOTAS...THOUGH BETTER PRECIP CHANCES WITH THIS LOOK TO ARRIVE
SUNDAY MORNING.
FOR CURRENT SNOW...CONTINUED TREND OF FAIRLY WIDESPREAD 1-2 INCHES
OF SNOW ACROSS THE ENTIRE AREA. ALL MODELS FROM THE HRRR AND
HOPWRF TO THE ECMWF/GFS SHOW FAIRLY WIDESPREAD TOTAL QPF AMOUNTS
BETWEEN 0.05 AND 0.10 INCHES...WHICH SHOULD BE ABLE TO TRANSLATE
INTO THE 1-2 INCH RANGE. THOUGH BUFKIT THERMAL PROFILES WITH THEIR
DEEP DENDRITIC GROWTH ZONES WOULD SUGGEST SEEING SNOW RATIOS IN
EXCESS OF 20:1...WEAK NATURE OF FORCING HAS PREVENTED ICE CRYSTAL
GROWTH FROM GETTING OUT OF HAND...KEEPING SNOW TYPE AS MAINLY FINE
CRYSTALS. HENCE WHY 12-15 HOURS OF LIGHT SNOW IS ONLY EXPECTED TO
NET 1 TO 2 INCHES OF ACCUMULATIONS.
FOR TEMPERATURES...TODAY WILL BE SIMILAR TO FRIDAY AS CLOUDS
COMBINED WITH NORTH WINDS BRINGING DOWN THE ARCTIC AIR THAT IS
SITTING UP IN NRN MN HELPING TO LIMIT DIURNAL RANGES TODAY TO 5
DEGREES OR LESS. TONIGHT...THE ARCTIC AIR WILL FINALLY BE PUSHING
INTO THE MPX AREA...WHICH SHOULD ALLOW JUST ABOUT EVERYONE TO DIP
BELOW ZERO. TRENDED FORECAST LOWS TONIGHT TOWARD BIAS CORRECTED
VERSIONS OF THE ECMWF AND MET...WHICH RESULTED IN KNOCKING CLOSE 5
DEGREES OFF OF THE EXISTING FORECAST. IF WE CAN GET SKIES TO CLEAR
OUT...THEN TEMPS COULD GET COLDER STILL...ESPECIALLY OVER CENTRAL
MN WHERE LOWS IN THE -20S BELOW ZERO WOULD NOT BE OUT OF QUESTION.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 312 AM CST SAT DEC 14 2013
COLD NW FLOW WILL PERSIST ON THE BACKSIDE OF THE POTENT ERN
SEABOARD STORM OR SUN INTO MON AS RIDGING DEVELOPS OVER THE W
COAST. WHILE SFC HIGH PRES OVER S-CENTRAL CANADA...EXTENDING SWD
INTO THE DAKOTAS AND MN/WI...SEVERAL WAVES DRIVING SEWD WITHIN THE
FLOW ALOFT WILL ENCOUNTER ENHANCED H7-H5 LIFT AND A SWATH OF
RELATIVELY DEEPER MOISTURE. THIS COMBINATION WILL PRODUCE LIGHT
SNOW FOR SUN INTO MON. THOUGH WAA WILL COMMENCE DURG THE DAY ON
MON...THIS WAVE LOOKS TO EXIT THE REGION FAST ENOUGH SUCH THAT ANY
AND ALL PRECIP FROM IT SHALL REMAIN AS ALL -SN. SNOWFALL
ACCUMULATIONS WILL GENERALLY RANGE 1-2 INCHES...THOUGH IT IS
POSSIBLE THAT FAR ERN PORTIONS OF THE MPX CWFA /SPECIFICALLY...A
FEW WRN WI COUNTIES/ MAY RECEIVE UPWARDS OF 3-4 INCHES. STILL A
LITTLE BIT OF TIME TO IRON OUT THESE DETAILS.
MORE EXTENSIVE HIGH PRES WITH WARMER TEMPERATURES WILL CROSS THE
REGION TUE INTO WED...RESULTING IN HIGHER H5 HEIGHTS PRODUCING MAX
TEMPS INTO THE LOW-MID 20S WITH NO PRECIP EXPECTED.
ATTENTION THEN STILL IS FOCUSED ON THE END OF THE WEEK DUE TO THE
DEVELOPMENT OF A POTENT STORM SYSTEM DEVELOPING IN THE LEE OF THE
ROCKIES. AIDING THE DEVELOPMENT WILL BE THE WRN CONUS RIDGE
SHIFTING ACRS THE COUNTRY...PLACING THE SRN JET OVER THE
CYCLOGENESIS REGION AND ALLOWING A TRACK FOR IT TO MOVE NE. THERE
IS STILL MUCH UNCERTAINTY WITH REGARDS TO THE TRACK AND THE AMOUNT
OF WARM AIR ENTRAINED WITHIN THE SYSTEM. ATTM...THE TRACK OF THE
LOW PRES CENTER REMAINS S OF THE MPX CWFA...WHICH WOULD INDICATE
THAT THE PREVAILING P-TYPE IS -SN. HAVE ADVERTISED AS SUCH
ALTHOUGH THERE IS THE CAVEAT THAT IF THE TRACK SHIFTS FURTHER
N...THEN MULTIPLE P-TYPES MAY WELL BE INTRODUCED IN LATER
FORECASTS. THE SYSTEM DOES LOOK TO BE RATHER QUICK... TRACKING
FROM THE CO REGION NEWD INTO THE GREAT LAKES IN ABOUT 24 HRS. WITH
DEEP LONGWAVE TROUGHING AIDING ITS MOVEMENT...THE PRONOUNCED NW
FLOW BEHIND THIS SYSTEM WILL BRING DOWN ANOTHER ROUND OF ARCTIC
AIR STARTING THU NIGHT AND LASTING NOT ONLY FRIDAY BUT ALSO INTO
THE WEEKEND. SO...ALTHOUGH THERE IS LITTLE CONFIDENCE IN THE
DETAILS...THE OVERALL SCENARIO OF SEEING A POTENT WINTER STORM
FOLLOWED BY MUCH COLDER AIR IS LOOKING MORE REALISTIC BY THE MODEL
RUN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1012 PM CST FRI DEC 13 2013
REFLECTIVITY HAS FLOURISHED SINCE LAST UPDATE A FEW HOURS AGO.
INTERESTINGLY...THE HI RES MODELS TRY TO SHOW THIS BROAD AREA OF
LIGHT SNOW ESSENTIALLY DISAPPEARING BEFORE COMING BACK AROUND 10Z.
I DONT SEE A LOGICAL REASON FOR THIS...SO KEPT THE SNOW IN THE
FORECAST ACROSS THE AREA. LIFT IS STILL NOT IMPRESSIVE...BUT THE
MODEL SOUNDINGS DO INDICATE A VERY DEEP DENDRITIC GROWTH ZONE
WHICH WILL ONLY HELP LOWER VSBYS AND ACCUMULATION TO OCCUR. EXPECT
GENERALLY A DUSTING TO TWO INCHES ACROSS THE FA...WITH A FEW SPOTS
EXCEEDING TWO INCHES OF ACCUMULATION. CEILINGS HAVE RAPIDLY
LOWERED AT MOST SITES...AND SHOULD STAY DOWN THROUGH THE NIGHT.
WINDS OUT OF THE NORTHEAST WILL EVENTUALLY BACK TO NW BY
TOMORROW AFTN.
KMSP...SNOWFALL WITH CEILINGS CONTINUING TO FALL TO AROUND 015
OVERNIGHT IS EXPECTED. ONE TO TWO INCHES OF ACCUMULATION LIKELY BY
MIDDAY SUNDAY. HEAVIEST SNOW EXPECTED TO LIGHTEN UP AROUND
13Z...BUT VERY LIGHT SNOW COULD LINGER INTO THE AFTERNOON.
/OUTLOOK FOR KMSP/
SUN...MVFR CIGS PSBL. CHC OF -SN LATE. WINDS NW 5 KTS.
MON...MVFR CIGS PSBL. CHC OF -SN EARLY. WINDS SW 5-10 KTS.
TUE...VFR. WINDS WNW 10-15 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...MPG
LONG TERM...JPC
AVIATION...SPD
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
920 PM CST Sun Dec 15 2013
.UPDATE:
Issued at 849 PM CST Sun Dec 15 2013
A well-defined baroclinic zone reaching from the Dakotas
southeastward through northwest Missouri has extended through east
central Missouri and into southwest Illinois this evening, and
makes for a bit of a tricky forecast overnight tonight. Despite
uncertainties associated with this baroclinic zone, feel that
overall, the going forecast this evening remains on track.
Pockets of light snow have continued over Iowa and Illinois in
response to a vort max moving within the northwest flow aloft, and
while much of the activity looks to remain north of the area,
still cannot rule out some light freezing rain or light snow,
mainly over the northern periphery of the forecast area. The most
recent run of the HRRR supports this, indicating spotty
precipitation over the next few hours over northeast Missouri and
west central Illinois. Near and south of the baroclinic zone,
dewpoints this evening are still hanging in the middle to upper
20s, thus feel that the mention of fog for this area continues to
be warranted tonight as temperatures fall. Beyond adjusting near
term trends based on current observations, no major changes have
been warranted this evening.
JP
&&
.SHORT TERM: (Tonight through Monday)
Issued at 259 PM CST Sun Dec 15 2013
Lots of caveats to the forecast for tonight leading to low confidence
in some of the details. A strong surface front currently extends
from western SD through central NE and northeast KS across northern
MO into west central IL. The models are in decent agreement that a
surface low pressure wave will track southeastward along the front
from the central Plains into southern IL tonight with the front
sagging southward in its wake. This surface low will be in response
to a weak elongated short wave/vort max migrating southeastward
within the NW flow aloft. The large scale forcing and strongest
low level baroclinicity/frontogenesis will reside to the north of
the forecast area from Iowa thru north central IL into southeast
IN and this is where the greatest threat of snow should reside.
Along the far southern periphery of this zone which encompasses a
zone from around Edina to Quincy to White Hall to Nokomis, the RAP
suggests there could be a brief shot of decent ascent. It also has
some very light QPF within this zone and the last few available
runs of the HRRR showed some spotty precipitation. The overall low
level flow regime is characterized south of the aforementioned
front and above the boundary layer by warm air advection. This WAA
while also contributing to lift has warmed the atmosphere and
soundings suggest any precipitation could teeter between light
freezing rain or light snow. I have added some low pops to account
for this probability and it will bear close watching on the
evening shift. Further south snow melt has contributed to low
level moistening and some of the guidance suggests fog and stratus
will develop. The 12z run of the NAM even went as far as developing
freezing drizzle. The boundary layer is where all the models have
the poorest time resolving, thus my confidence is limited, but
given the current surface dew points are now close to the forecast
mins I have opted to included a mention of fog in the forecast. If
stratus and fog are widespread on Monday morning, then the trend
should be for this to erode/dissipate as the morning progresses
and weak low level WAA kicks in. If the stratus/fog or clouds are
at a minimum then my forecast highs are likely to cool.
Glass
.LONG TERM: (Monday Night through Next Sunday)
Issued at 259 PM CST Sun Dec 15 2013
Despite another weak and ill-defined cold front passing though the
area on Tuesday, the temperatures should moderate some. The real
moderation however will begin to unfold on Tuesday night as the
surface high retreats and low level WAA gets underway. Strong WAA
will be in full swing on Wednesday as low level flow becomes
south/southwesterly and the upper flow transitions to quasi-zonal.
This should be a big snow melter with highs in the upper 40s-middle
50s.
The extended portion of the forecast, especially towards the
weekend, is marked by considerable uncertainty. A big pattern change
will continue to evolve with considerable amplification from the
central Pacific across the CONUS. The main feature will be the
development of a split flow regime with a deep long wave positively
tilted trof in the western U.S. and upper low in the southwest. This trof
develops in response to the absorption of an upper low currently in
the southeast Pacific near 27N/134W and short waves digging
southward out of the Gulf of AK along the west coast. The northern
stream will serve to bring a cold front through the area Thursday
night/early Friday accompanied by a chance of rain and possibly some
rain/snow mix in the wake. However the northern stream is sharper on
the GFS and it also leaves the upper low spinning in the vicinity of
northern Baja CA. This solution would suggest limited post-frontal
precipitation with high pressure building into the Mid MS Valley
late Friday and then additional waves in the northern stream
reinforcing the high pressure and essentially keeping precipitation
south of the area. Alternatively the ECMWF develops an overrunning
scenario Saturday into Sunday and potential for a winter mess.
There is no scientific basis at this point in time to suggest one
solution is vastly better than another and the models will continue
to change multiple times in the details in the coming week. Given
the forecast large scale pattern changes and vastly differing model
solutions and resultant low confidence, the best approach at this
time is more of an ensemblistic approach with some mixed flavor.
Glass
&&
.AVIATION: (For the 00z TAFs through 00z Monday Evening)
Issued at 554 PM CST Sun Dec 15 2013
A low pressure system passing through the region may bring a few
hours of light snow to KUIN however snow is expected to remain
north and east of the other TAF sites. With the additional low
level moisture provided by melting snow, the key questions for
tonight concern the development and timing of MVFR to IFR
conditions. BUFKIT soundings from the RAP show light winds and a
strong surface-based inversion along with nearly saturated
conditions at the lowest levels, suggesting that fog will develop
and then lift to stratus around 14-17z. Stratus is likely to
linger for most of the day due to poor mixing and low sun angle.
There is low confidence in the timing of MVFR/IFR onset (and
whether the restrictions will be due to fog, stratus, or both) but
reasonable confidence that MVFR/IFR conditions will occur for
several hours between 03z and 12z.
Specifics for KSTL: Fog, stratus, or both are expected to develop
tonight due to the additional low level moisture provided by
melting snow and at least some radiational cooling once mid clouds
begin to thin out. BUFKIT soundings from the RAP show light winds
through the lowest 1000 ft as well as a strong surface-based
inversion and nearly saturated conditions through 1400 ft, which
suggests that IFR restrictions would begin as fog before lifting
to stratus around 14-16z. IFR or MVFR stratus is likely to linger
for most of the day due to poor mixing and low sun angle. There is
low confidence in the timing of IFR onset (and whether the
restrictions will be due to fog, stratus, or both) but reasonable
confidence that IFR will occur for several hours between 03z and
12z.
Kanofsky
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
626 PM CST Sun Dec 15 2013
.SHORT TERM: (Tonight through Monday)
Issued at 259 PM CST Sun Dec 15 2013
Lots of caveats to the forecast for tonight leading to low confidence
in some of the details. A strong surface front currently extends
from western SD through central NE and northeast KS across northern
MO into west central IL. The models are in decent agreement that a
surface low pressure wave will track southeastward along the front
from the central Plains into southern IL tonight with the front
sagging southward in its wake. This surface low will be in response
to a weak elongated short wave/vort max migrating southeastward
within the NW flow aloft. The large scale forcing and strongest
low level baroclinicity/frontogenesis will reside to the north of
the forecast area from Iowa thru north central IL into southeast
IN and this is where the greatest threat of snow should reside.
Along the far southern periphery of this zone which encompasses a
zone from around Edina to Quincy to White Hall to Nokomis, the RAP
suggests there could be a brief shot of decent ascent. It also has
some very light QPF within this zone and the last few available
runs of the HRRR showed some spotty precipitation. The overall low
level flow regime is characterized south of the aforementioned
front and above the boundary layer by warm air advection. This WAA
while also contributing to lift has warmed the atmosphere and
soundings suggest any precipitation could teeter between light
freezing rain or light snow. I have added some low pops to account
for this probability and it will bear close watching on the
evening shift. Further south snow melt has contributed to low
level moistening and some of the guidance suggests fog and stratus
will develop. The 12z run of the NAM even went as far as developing
freezing drizzle. The boundary layer is where all the models have
the poorest time resolving, thus my confidence is limited, but
given the current surface dew points are now close to the forecast
mins I have opted to included a mention of fog in the forecast. If
stratus and fog are widespread on Monday morning, then the trend
should be for this to erode/dissipate as the morning progresses
and weak low level WAA kicks in. If the stratus/fog or clouds are
at a minimum then my forecast highs are likely to cool.
Glass
.LONG TERM: (Monday Night through Next Sunday)
Issued at 259 PM CST Sun Dec 15 2013
Despite another weak and ill-defined cold front passing though the
area on Tuesday, the temperatures should moderate some. The real
moderation however will begin to unfold on Tuesday night as the
surface high retreats and low level WAA gets underway. Strong WAA
will be in full swing on Wednesday as low level flow becomes
south/southwesterly and the upper flow transitions to quasi-zonal.
This should be a big snow melter with highs in the upper 40s-middle
50s.
The extended portion of the forecast, especially towards the
weekend, is marked by considerable uncertainty. A big pattern change
will continue to evolve with considerable amplification from the
central Pacific across the CONUS. The main feature will be the
development of a split flow regime with a deep long wave positively
tilted trof in the western U.S. and upper low in the southwest. This trof
develops in response to the absorption of an upper low currently in
the southeast Pacific near 27N/134W and short waves digging
southward out of the Gulf of AK along the west coast. The northern
stream will serve to bring a cold front through the area Thursday
night/early Friday accompanied by a chance of rain and possibly some
rain/snow mix in the wake. However the northern stream is sharper on
the GFS and it also leaves the upper low spinning in the vicinity of
northern Baja CA. This solution would suggest limited post-frontal
precipitation with high pressure building into the Mid MS Valley
late Friday and then additional waves in the northern stream
reinforcing the high pressure and essentially keeping precipitation
south of the area. Alternatively the ECMWF develops an overrunning
scenario Saturday into Sunday and potential for a winter mess.
There is no scientific basis at this point in time to suggest one
solution is vastly better than another and the models will continue
to change multiple times in the details in the coming week. Given
the forecast large scale pattern changes and vastly differing model
solutions and resultant low confidence, the best approach at this
time is more of an ensemblistic approach with some mixed flavor.
Glass
&&
.AVIATION: (For the 00z TAFs through 00z Monday Evening)
Issued at 554 PM CST Sun Dec 15 2013
A low pressure system passing through the region may bring a few
hours of light snow to KUIN however snow is expected to remain
north and east of the other TAF sites. With the additional low
level moisture provided by melting snow, the key questions for
tonight concern the development and timing of MVFR to IFR
conditions. BUFKIT soundings from the RAP show light winds and a
strong surface-based inversion along with nearly saturated
conditions at the lowest levels, suggesting that fog will develop
and then lift to stratus around 14-17z. Stratus is likely to
linger for most of the day due to poor mixing and low sun angle.
There is low confidence in the timing of MVFR/IFR onset (and
whether the restrictions will be due to fog, stratus, or both) but
reasonable confidence that MVFR/IFR conditions will occur for
several hours between 03z and 12z.
Specifics for KSTL: Fog, stratus, or both are expected to develop
tonight due to the additional low level moisture provided by
melting snow and at least some radiational cooling once mid clouds
begin to thin out. BUFKIT soundings from the RAP show light winds
through the lowest 1000 ft as well as a strong surface-based
inversion and nearly saturated conditions through 1400 ft, which
suggests that IFR restrictions would begin as fog before lifting
to stratus around 14-16z. IFR or MVFR stratus is likely to linger
for most of the day due to poor mixing and low sun angle. There is
low confidence in the timing of IFR onset (and whether the
restrictions will be due to fog, stratus, or both) but reasonable
confidence that IFR will occur for several hours between 03z and
12z.
Kanofsky
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1116 AM CST Sat Dec 14 2013
.SHORT TERM...(Today through Sunday Night)
Issued at 313 AM CST SAT DEC 14 2013
Winter storm is departing the region early this morning. Lingering
areas of drizzle will cause some minor icing from eastern KS into
western and central MO through sunrise as temperatures continue to
drop below freezing. Additional snow amounts will be mostly confined
to areas around Boonville and Moberly where another inch or so is
possible through early morning. An additional band of light snow has
developed from Kansas City into Chillicothe and Kirksville in
response to a narrow band of frontogenesis. RAP and NAM hold on to
this frontogenetical forcing through about 12Z and drop it to near
I-70, so it`s conceivable for this area of snow to hold together for
a few more hours and produce a dusting of snow with local amounts up
to a half inch near and northeast of KC. With temperatures falling
below freezing, any light snow that falls may fall on top of ice
developing on roads as lingering water freezes. Will therefore keep
the advisory going through 9 am as planned.
Precipitation will taper off from northwest to southeast through mid
morning. There`s a slight chance for some flurries or freezing
drizzle to redevelop late this morning into early afternoon as the
main upper trough axis swings through and interacts with low-level
cold air advection. Anything that does fall through this period
should be very light if anything at all.
Clouds will begin to scatter out later this afternoon and evening
with low-level ridging building in from the west. This will allow
temperatures to drop well into the single digits across northern and
central MO where a decent snow pack exists. Temperatures will begin
to moderate by Sunday and Sunday night with conditions returning to
near average.
.LONG TERM...(Monday through Friday)
Issued at 313 AM CST SAT DEC 14 2013
Monday - Tuesday:
General troughing across eastern Canada and the northern Great Lakes
will keep the area under benign northwest flow aloft. Nearer the
surface, downsloping westerly flow will allow temperatures to climb
where there is no snowpack. Highs across east central Kansas and
west central Missouri will rise into the mid to upper 40s whereas
across north central Missouri, where there is snowpack, highs will
only reach the mid to upper 30s. Tuesday a weak cold front will drop
through the area however this will have little effect on
temperatures as highs Tuesday should again range in the upper 30s to
upper 40s.
Wednesday:
The upper level pattern begins to shift on Wednesday becoming more
zonal across the region. Surface winds will also increase out of the
south providing for WAA and highs will be in the upper 30s to near
50. The next feature of interest, in the form of an upper level
trough, will move into the southwestern CONUS.
Thursday - Friday:
Models are in a bit of disagreement this far in the extended range.
However, the ECMWF, GFS and GEM all show the upper level shortwave
moving into the western Plains on Thursday and forcing a strong cold
front towards the area. Warm moist air streaming out ahead of this
front may produce light rain or drizzle on Thursday as high
temperatures move above average into the mid 40s to mid 50s. Models
depict rain changing to snow behind the front as it moves through
the area on Thursday night. The model differences occur on Friday as
the GFS stalls the front south of the area with snow continuing
through the day Friday whereas, the EC builds high pressure into the
area keeping conditions dry. On Friday, left the chance POPs in the
grids inherited by the initialization to account for the GFS
solution.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1114 AM CST SAT DEC 14 2013
A gradual improvement from the current MVFR cigs/vis is expected
over the next few hours. May see borderline MVFR/VFR cloud deck
currently over SE NE to approach from the north late this afternoon.
Period of clearing will be possible post-sunset before another wave
of VFR cloud cover moves into the area. Otherwise, wind speeds will
gradually decrease during the afternoon with a variable direction
overnight.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...Hawblitzel
LONG TERM...73
AVIATION...Blair
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
528 AM CST Sat Dec 14 2013
.SHORT TERM...(Today through Sunday Night)
Issued at 313 AM CST SAT DEC 14 2013
Winter storm is departing the region early this morning. Lingering
areas of drizzle will cause some minor icing from eastern KS into
western and central MO through sunrise as temperatures continue to
drop below freezing. Additional snow amounts will be mostly confined
to areas around Boonville and Moberly where another inch or so is
possible through early morning. An additional band of light snow has
developed from Kansas City into Chillicothe and Kirksville in
response to a narrow band of frontogenesis. RAP and NAM hold on to
this frontogenetical forcing through about 12Z and drop it to near
I-70, so it`s conceivable for this area of snow to hold together for
a few more hours and produce a dusting of snow with local amounts up
to a half inch near and northeast of KC. With temperatures falling
below freezing, any light snow that falls may fall on top of ice
developing on roads as lingering water freezes. Will therefore keep
the advisory going through 9 am as planned.
Precipitation will taper off from northwest to southeast through mid
morning. There`s a slight chance for some flurries or freezing
drizzle to redevelop late this morning into early afternoon as the
main upper trough axis swings through and interacts with low-level
cold air advection. Anything that does fall through this period
should be very light if anything at all.
Clouds will begin to scatter out later this afternoon and evening
with low-level ridging building in from the west. This will allow
temperatures to drop well into the single digits across northern and
central MO where a decent snow pack exists. Temperatures will begin
to moderate by Sunday and Sunday night with conditions returning to
near average.
.LONG TERM...(Monday through Friday)
Issued at 313 AM CST SAT DEC 14 2013
Monday - Tuesday:
General troughing across eastern Canada and the northern Great Lakes
will keep the area under benign northwest flow aloft. Nearer the
surface, downsloping westerly flow will allow temperatures to climb
where there is no snowpack. Highs across east central Kansas and
west central Missouri will rise into the mid to upper 40s whereas
across north central Missouri, where there is snowpack, highs will
only reach the mid to upper 30s. Tuesday a weak cold front will drop
through the area however this will have little effect on
temperatures as highs Tuesday should again range in the upper 30s to
upper 40s.
Wednesday:
The upper level pattern begins to shift on Wednesday becoming more
zonal across the region. Surface winds will also increase out of the
south providing for WAA and highs will be in the upper 30s to near
50. The next feature of interest, in the form of an upper level
trough, will move into the southwestern CONUS.
Thursday - Friday:
Models are in a bit of disagreement this far in the extended range.
However, the ECMWF, GFS and GEM all show the upper level shortwave
moving into the western Plains on Thursday and forcing a strong cold
front towards the area. Warm moist air streaming out ahead of this
front may produce light rain or drizzle on Thursday as high
temperatures move above average into the mid 40s to mid 50s. Models
depict rain changing to snow behind the front as it moves through
the area on Thursday night. The model differences occur on Friday as
the GFS stalls the front south of the area with snow continuing
through the day Friday whereas, the EC builds high pressure into the
area keeping conditions dry. On Friday, left the chance POPs in the
grids inherited by the initialization to account for the GFS
solution.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday Morning)
Issued at 528 AM CST SAT DEC 14 2013
Wintry precipitation has ended for the Kansas City and St. Joseph
areas. Lingering light snow and drizzle will end by 14Z for the DMO
area. IFR ceilings will likely lift to low-end MVFR shortly and
remain there for the remainder of the day.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...WINTER WEATHER ADVISORY until 9 AM CST this morning FOR KSZ025-
057-060-102>105.
MO...WINTER WEATHER ADVISORY until 9 AM CST this morning FOR
MOZ004>008-012>017-020>025-028>033-037>040-043>046-053-054.
&&
$$
SHORT TERM...Hawblitzel
LONG TERM...73
AVIATION...Hawblitzel
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
313 AM CST Sat Dec 14 2013
.SHORT TERM...(Today through Sunday Night)
Issued at 313 AM CST SAT DEC 14 2013
Winter storm is departing the region early this morning. Lingering
areas of drizzle will cause some minor icing from eastern KS into
western and central MO through sunrise as temperatures continue to
drop below freezing. Additional snow amounts will be mostly confined
to areas around Boonville and Moberly where another inch or so is
possible through early morning. An additional band of light snow has
developed from Kansas City into Chillicothe and Kirksville in
response to a narrow band of frontogenesis. RAP and NAM hold on to
this frontogenetical forcing through about 12Z and drop it to near
I-70, so it`s conceivable for this area of snow to hold together for
a few more hours and produce a dusting of snow with local amounts up
to a half inch near and northeast of KC. With temperatures falling
below freezing, any light snow that falls may fall on top of ice
developing on roads as lingering water freezes. Will therefore keep
the advisory going through 9 am as planned.
Precipitation will taper off from northwest to southeast through mid
morning. There`s a slight chance for some flurries or freezing
drizzle to redevelop late this morning into early afternoon as the
main upper trough axis swings through and interacts with low-level
cold air advection. Anything that does fall through this period
should be very light if anything at all.
Clouds will begin to scatter out later this afternoon and evening
with low-level ridging building in from the west. This will allow
temperatures to drop well into the single digits across northern and
central MO where a decent snow pack exists. Temperatures will begin
to moderate by Sunday and Sunday night with conditions returning to
near average.
.LONG TERM...(Monday through Friday)
Issued at 313 AM CST SAT DEC 14 2013
Monday - Tuesday:
General troughing across eastern Canada and the northern Great Lakes
will keep the area under benign northwest flow aloft. Nearer the
surface, downsloping westerly flow will allow temperatures to climb
where there is no snowpack. Highs across east central Kansas and
west central Missouri will rise into the mid to upper 40s whereas
across north central Missouri, where there is snowpack, highs will
only reach the mid to upper 30s. Tuesday a weak cold front will drop
through the area however this will have little effect on
temperatures as highs Tuesday should again range in the upper 30s to
upper 40s.
Wednesday:
The upper level pattern begins to shift on Wednesday becoming more
zonal across the region. Surface winds will also increase out of the
south providing for WAA and highs will be in the upper 30s to near
50. The next feature of interest, in the form of an upper level
trough, will move into the southwestern CONUS.
Thursday - Friday:
Models are in a bit of disagreement this far in the extended range.
However, the ECMWF, GFS and GEM all show the upper level shortwave
moving into the western Plains on Thursday and forcing a strong cold
front towards the area. Warm moist air streaming out ahead of this
front may produce light rain or drizzle on Thursday as high
temperatures move above average into the mid 40s to mid 50s. Models
depict rain changing to snow behind the front as it moves through
the area on Thursday night. The model differences occur on Friday as
the GFS stalls the front south of the area with snow continuing
through the day Friday whereas, the EC builds high pressure into the
area keeping conditions dry. On Friday, left the chance POPs in the
grids inherited by the initialization to account for the GFS
solution.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday Night)
Issued at 1133 PM CST FRI DEC 13 2013
Light to moderate snow will continue to shift east out of the region
during the early morning hours, leaving behind some light drizzle and
patchy fog across the area. As temperatures fall over the next few
hours, freezing drizzle will be possible in areas mainly south of Hwy
36. Drier, colder air will work down from the north during the morning,
eventually helping ceilings to lift out of the LIFR category and also
bringing increased northerly winds in the 10 to 15 kt range. Stratus
is expected to scatter out from north to south during the early to
mid afternoon hours, leaving behind VFR conditions for the end of the
TAF period.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...WINTER WEATHER ADVISORY until 9 AM CST this morning FOR KSZ025-
057-060-102>105.
MO...WINTER WEATHER ADVISORY until 9 AM CST this morning FOR
MOZ004>008-012>017-020>025-028>033-037>040-043>046-053-054.
&&
$$
SHORT TERM...Hawblitzel
LONG TERM...73
AVIATION...Laflin
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1012 PM EST SUN DEC 15 2013
.SYNOPSIS...
A COLD WEST FLOW OF AIR CROSSING THE LOWER GREAT LAKES WILL CONTINUE
TO GENERATE LAKE EFFECT SNOWS EAST AND SOUTHEAST OF THE LAKES INTO
MONDAY. A CLIPPER SYSTEM BRINGS ANOTHER GENERAL LIGHT SNOWFALL
MONDAY NIGHT THROUGH TUESDAY NIGHT. TEMPERATURES WILL RISE ABOVE
NORMAL TOWARD THE END OF THE WEEK WITH A CHANCE FOR RAIN FRIDAY
AHEAD OF THE NEXT STORM SYSTEM.
&&
.NEAR TERM /THROUGH MONDAY/...
MADE A FEW CHANGES TO THE LAKE EFFECT HEADLINES THIS EVENING. THE
SOUTHWEST-NORTHEAST ORIENTED LAKE BAND WHICH BROUGHT WHITE OUT
CONDITIONS AND 3 IN/HR SNOWFALL RATES TO THE BUFFALO SOUTHTOWNS HAS
SINCE WEAKENED SOME AND SHIFTED BACK SOUTH ACROSS THE SOUTHERN TIER
WITH WINDS VEERING TO WESTERLY. A LAKE EFFECT SNOW WARNING CONTINUES
ACROSS CHAUTAUQUA AND CATTARAUGUS COUNTIES THROUGH MIDNIGHT AS THE
BAND IS STILL SHOWING ONE TO TWO INCH PER HOUR SNOWFALL RATES. LAKE
EFFECT SNOW ADVISORY HAS BEEN ADDED FOR ALLEGANY AS THE LAKE BAND IS
EXTENDING EAST ACROSS THE NORTHERN HALF OF THE COUNTY WITH SNOWFALL
RATES OF A HALF TO ONE INCH PER HOUR. MESOSCALE GUIDANCE INCLUDING
THE HRRR AND RGEM SHOW LAKE SNOWS WILL CONTINUE AFTER MIDNIGHT BUT
SHOULD BE IN A BIT WEAKER STATE AS THE SHORTER FETCH ACROSS THE LAKE
BREAKS THE BAND INTO WEAKER MULTI-BANDS. HEADLINES WILL BE
RE-EVALUATED TOWARD MIDNIGHT FOR EXTENSION BASED ON RADAR TRENDS.
OFF LAKE ONTARIO...A STRONGER LONG AXIS PARALLEL LAKE BAND IS
ONGOING EAST OF THE LAKE. THE BAND IS CENTERED ON THE
OSWEGO/JEFFERSON COUNTY BORDER. RADAR IS SHOWING SNOWFALL RATES OF
ONE TO ONE AND A HALF INCHES PER HOUR BETWEEN SANDY CREEK AND
MANNSVILLE WITH LOCALLY HIGHER RATES POSSIBLE. A LAKE EFFECT SNOW
ADVISORY WAS ADDED TO JEFFERSON COUNTY TO COVER FOR A SHORT PERIOD
OF HEAVY SNOW THIS EVENING WITH THE LEWIS COUNTY ADVISORY
CONTINUING. MESOSCALE GUIDANCE HERE SUGGESTS THE BAND WILL MAINTAIN
A WEST-EAST ORIENTATION THROUGH MIDNIGHT THEN BEGIN TO DRIFT SOUTH
AS STEERING WINDS VEER TO NORTHWESTERLY BEHIND A SURFACE TROUGH
SHIFTING SOUTH JUST TO THE NORTH OF THE LAKE. THE BAND WILL DRIFT SOUTH
BETWEEN 4-8Z THEN RUN ALONG THE SOUTHEASTERN LAKE ONTARIO SHORELINE
THROUGH THE REMAINDER OF THE NIGHT. THE HIGHER QPF IS EXPECTED
ACROSS OSWEGO COUNTY THROUGH THE EVENT SO THIS COUNTY HAS BEEN
UPGRADED TO A WARNING. SNOWFALL RATES OF ONE-TWO OR MORE INCHES PER
HOUR CAN BRING 6-12 INCHES OF SNOW POSSIBLY OVERNIGHT. ONCE THE BAND
BECOMES MORE NORTHWEST-SOUTHEAST ORIENTED THEN LAKE SNOWS WILL BEGIN
TO ACCUMULATE ACROSS NORTHERN CAYUGA AND WAYNE COUNTIES TOWARD EARLY
MONDAY MORNING.
MONDAY...ONGOING WEAKER NORTHWEST FLOW LAKE EFFECT SNOWS IN THE MORNING
SHOULD DECREASE IN INTENSITY WITH DEPLETING MOISTURE PROFILES AND
LOWERING INVERSIONS. NAM BUFKIT PROFILES SHOW INVERSIONS LOWERING
BELOW 10KFT TOWARD 18Z AS WEAK HIGH PRESSURE NOSES DOWN ACROSS THE
LOWER GREAT LAKES. TEMPERATURES WILL REMAIN VERY COLD WITH HIGHS
LIMITED TO THE TEENS ACROSS WNY AND SINGLE DIGITS EAST OF LAKE
ONTARIO. WIND CHILLS UNDER A WEST TO NORTHWEST FLOW WILL RUN A SOLID
10 DEGREES BELOW OBSERVED SURFACE TEMPS. OUTSIDE OF THE LAKE EFFECT
SOME SUNSHINE SHOULD BREAK OUT TOWARD THE AFTERNOON AS THE HIGH
PRESSURE BUILDS OVERHEAD WITH MAINLY DRY BUT COLD CONDITIONS.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
TO START THIS TIME PERIOD LAKE EFFECT SNOW WILL LIKELY BE ONGOING
EAST OF BOTH LAKES. AT THE SURFACE HIGH PRESSURE WILL QUICKLY PASS
ACROSS THE REGION MONDAY NIGHT...AND WHILE WINDS WILL BACK SOME
AHEAD OF THE AREA OF HIGH PRESSURE SENDING LAKE EFFECT SNOW
NORTHWARD...INCREASING WIND SHEAR AND BRIEF PASSAGE OF DRIER AIR
WILL QUICKLY ERODE AWAY THE SNOW BANDS.
THE 12Z OPERATIONAL MODEL RUNS ARE COMING INTO BETTER ALIGNMENT WITH
A STRENGTHENING RIDGE OF HIGH PRESSURE OVER THE WEST...WITH SEVERAL
SHORTWAVES DIVING SOUTHWARD ACROSS THE GREAT LAKES REGION. EACH OF
THESE WAVES OF LOW PRESSURE WILL LIKELY BRING A BURST OF SNOW TO THE
REGION...GENERALLY SEVERAL INCHES TO LOW END ADVISORY LEVEL
SNOWS...WITH THE FIRST WAVE ARRIVING LATER MONDAY NIGHT.
WEAK ISENTROPIC UPGLIDE AHEAD OF THE SHORTWAVE...COMBINED WITH
DIFFLUENT FLOW AHEAD OF THE SHORTWAVE PROMOTING VERTICAL UPLIFT
SHOULD BRING A LIGHT SNOW TO WESTERN NEW YORK OVERNIGHT...AND
REACHING EASTERN ZONES LATE MONDAY NIGHT OR EARLY TUESDAY.
BEHIND THE FIRST SHORTWAVE TROUGH A SHORTWAVE RIDGE WILL CROSS THE
REGION TUESDAY WITH PRECIPITATION CHANCES TRENDING DOWN WITH THE
LOSS OF UPWARD MOTION. HOWEVER THE NEXT SHORTWAVE WILL ARRIVE
TUESDAY NIGHT WITH ANOTHER ROUND OF LIGHT SNOW ACROSS THE REGION.
ON WEDNESDAY NORTHWEST FLOW WILL CONTINUE ALOFT...WHILE HIGH
PRESSURE AT THE SURFACE CENTERED OVER THE TENNESSEE VALLEY WILL BRING
MORE OF A WEST TO EAST FLOW ACROSS THE GREAT LAKES. TEMPERATURES AT
850 HPA WILL BE JUST COLD ENOUGH TO PROMOTE INSTABILITY FOR ANOTHER
ROUND OF LAKE EFFECT SNOWS...WITH THE LAKES NOW COOLED DOWN TO
AROUND +2C ON ERIE AND +3-4C ON LAKE ONTARIO. FALLING LAKE INDUCED
EQUILIBRIUM LEVELS AND LOWERING INVERSION HEIGHTS THROUGH THE DAY
WILL NOT MAKE FOR AN IDEAL LAKE EFFECT SNOW SET UP THAT WE SAW
LAST WEEK. STILL SEVERAL ADDITIONAL INCHES OF SNOW ARE POSSIBLE
THROUGH THE DAY WEDNESDAY...TAPERING OFF WEDNESDAY NIGHT. OUTSIDE
OF THESE LAKE BANDS SOME SUNSHINE IS POSSIBLE.
TEMPERATURES WILL LIKELY REMAIN JUST BELOW NORMAL THROUGH THE TIME
PERIOD...AND NOT AS COLD AS IN PRIOR DAYS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A BRIEF PATTERN CHANGE WILL EVOLVE THIS TIME PERIOD AS A LONG WAVE
TROUGH FLATTENS THE WESTERN US RIDGE. IN RESPONSE DOWNSTREAM A RIDGE
OF HIGH PRESSURE WILL DEVELOP ACROSS THE EAST COAST...THOUGH THE
COLD POLAR LOW DROPPING SOUTHWARD TO HUDSON BAY WILL LIKELY RESTRICT
THE AMPLIFICATION OF THE RIDGE.
THIS WILL BRING SOME WARMING TEMPERATURES TO THE AREA TO START THE
TIME PERIOD. MODELS ARE STILL SHOWING SOME INCONSISTENCIES WITH
THE TIMING OF THE EJECTION OF THE CUT OFF LOW OVER THE DESERT
SOUTHWEST. THIS CUT OFF LOW OVER THE SOUTHWEST WILL EVENTUALLY EJECT
FROM THE SOUTHWEST AND LIKELY INTERACT WITH THE NORTHERN BRANCH OF
THE JET STREAM.
WILL BRING SOME CHANCE POPS ACROSS THE REGION FOR NEXT WEEKEND AS
SHORTWAVES WITHIN THE NORTHERN BRANCH OF THE JET STREAM CROSS THE
AREA. WITH THE 12Z MODELS BACKING OFF ON THE TIMING OF THE EJECTION
OF THE DESERT CUT OFF LOW...A DEEPER LOW POSING A LARGER STORM
SYSTEM MAY NOT REACH THE AREA UNTIL THE BEGINNING OF NEXT WEEK.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
LAKE EFFECT SNOWS OFF LAKE ERIE HAVE SHIFTED SOUTH THIS EVENING NOW
STEAMING EAST ACROSS THE SOUTHERN TIER WITH IFR CONDITIONS AT KJHW.
LAKE EFFECT WILL CONTINUE BUT IN AN MUCH WEAKENED STATE THROUGH THE
OVERNIGHT EVENTUALLY TAPERING OFF MONDAY MORNING. NORTH OF THIS LAKE
EFFECT VFR IS ONGOING AND WILL CONTINUE THROUGH TOMORROW AT
KBUF/KIAG/KROC.
EAST OF LAKE ONTARIO AN INTENSE BAND OF LAKE EFFECT IS OBSERVED
BETWEEN KART AND KSYR. THE NORTHERN EDGE IS IMPACTING KART WITH IFR
CONDITIONS. LATER TONIGHT THIS BAND WILL SHIFT SOUTH TOWARD KSYR AND
KFZY WITH KART BECOMING VFR AGAIN. LAKE SNOWS WILL CONTINUE UNDER A
NORTHWEST FLOW THROUGH MONDAY MORNING THEN BEGIN TO TAPER OFF AS
HIGH PRESSURE BUILD OVERHEAD MONDAY AFTERNOON.
OUTLOOK...
MONDAY NIGHT...MAINLY VFR.
TUESDAY...SNOW SHOWERS LIKELY WITH AREAS OF MVFR/IFR.
WEDNESDAY...MAINLY VFR WITH A CHANCE OF SNOW SHOWERS...EXCEPT LAKE
EFFECT SNOW SHOWERS LIKELY SOUTHEAST OF THE LAKES WITH LOCAL IFR.
THURSDAY AND FRIDAY...MAINLY VFR.
&&
.MARINE...
BRISK WESTERLY WINDS ACROSS THE LAKE IS RESULTING IN A PERIOD OF
ADVISORY LEVEL WINDS AND WAVES ON BOTH LAKES TONIGHT LASTING INTO
MONDAY BEFORE HIGH PRESSURE BUILDS OVER THE REGION ALONG WITH
DIMINISHING WINDS. A CLIPPER SYSTEM WILL DROP SOUTH ACROSS THE LAKES
ON TUESDAY. WINDS AND WAVES WILL INCREASE AGAIN TUESDAY NIGHT INTO
WEDNESDAY BEHIND THIS PASSING CLIPPER SYSTEM.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR NYZ007-008.
LAKE EFFECT SNOW WARNING UNTIL 4 PM EST MONDAY FOR NYZ006.
LAKE EFFECT SNOW ADVISORY UNTIL 4 PM EST MONDAY FOR NYZ004-005.
LAKE EFFECT SNOW WARNING UNTIL MIDNIGHT EST TONIGHT FOR NYZ019-
020.
LAKE EFFECT SNOW ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
NYZ012-021.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST MONDAY FOR LEZ040-041.
SMALL CRAFT ADVISORY UNTIL 7 PM EST MONDAY FOR
LOZ043>045.
SMALL CRAFT ADVISORY UNTIL 1 PM EST MONDAY FOR LOZ042.
&&
$$
SYNOPSIS...SMITH
NEAR TERM...SMITH
SHORT TERM...THOMAS
LONG TERM...THOMAS
AVIATION...SMITH
MARINE...SMITH/TMA
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
556 PM EST SAT DEC 14 2013
.SYNOPSIS...
LOW PRESSURE WILL PASS WEST OF THE AREA TONIGHT...BRINGING PERIODS OF
RAIN INTO SUNDAY. A COLD FRONT WILL CROSS THE COAST EARLY ON
SUNDAY...BRINGING COOL AND DRY WEATHER INTO EARLY NEXT WEEK. DRY
AND SEASONABLE WEATHER EXPECTED MUCH OF NEXT WEEK AS SURFACE HIGH
PRESSURE IS REINFORCED OVER THE AREA. A LOW PRESSURE SYSTEM WILL
APPROACH THE AREA NEXT WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 PM SATURDAY...SWIFT COLUMN WINDS ARE TRANSPORTING
INCREASING MOISTURE INTO THE AREA AS PRECIPITABLE WATERS CLIMB
THIS AFTERNOON ACROSS THE FORECAST AREA. KLTX VAD WIND PROFILE
CLOCKING 40 KNOT BARBS IN THE LOWEST GATES ADVECTING HIGHER
BOUNDARY LAYER DEWPOINTS OFF THE ATLANTIC ONTO LAND...WHILE ALOFT
A 50-70 KT SOUTHWEST TRAJECTORIES WERE STREAMING GULF MOISTURE
INTO THE CAROLINAS. LATEST SATELLITE-SENSED PWAT LOOPS DEPICT PWAT
VALUES IN EXCESS OF 1-INCH CROSSING THE SC/NC BORDER.
A WARM FRONT IS PUSHING NW ACROSS OUR FORECAST AREA PRESENTLY.
GUSTY SE WINDS AND RISING T/TD VALUES CHARACTERIZED CONDITIONS
EAST OF THE BOUNDARY. THIS TREND WILL CONTINUE INTO EARLY EVENING
INCREASING INSTABILITY OVER THE AREA AND MOST NOTABLY ALONG THE
COAST WHERE HIGHER TD VALUES ARE ANTICIPATED.
A NEARLY MOIST ADIABATIC SOUNDING PROFILE TONIGHT WILL LIMIT
OVERALL INSTABILITY BUT MOST OF THE MODELS APPEAR TO GENERATE CAPE
VALUES THIS EVENING SUFFICIENT FOR A FEW UPDRAFTS...AND BESIDES WE
SHOULD HAVE ADEQUATE JET SUPPORT ALOFT. OVERLAYED TEMPORALLY WITH
THIS INSTABILITY MAXIMA MAINLY BETWEEN 0Z/7PM AND 6Z/1AM...ARE
ELEVATED 0-3 KM HELICITY VALUES...AS CYCLOGENESIS PROMPTS A
DEEPENING WAVE OF LOW PRESSURE ALONG THE FRONT THAT TRACKS OVER
THE AREA THIS EVENING. THERE REMAINS ENOUGH INGREDIENTS TO RETAIN
A MENTION OF POTENTIALLY DAMAGING WINDS WITH ANY THUNDERSTORMS
THAT MAY FORM...DUE TO DYNAMIC WIND-FIELDS AND FAVORABLE HELICITY
AND HODOGRAPH PROFILES. THE BEST VERTICAL SHEAR PROFILES CONTINUE
TO REMAIN ALONG THE COAST AND COASTAL INTERIOR ALTHOUGH ANY ONE
LOCATION ACROSS THE FORECAST AREA WOULD POSSESS A SMALL CHANCE OF
WIND-DAMAGE AS THE FRONT TRANSITS.
COOL AIR ADVECTION LATER TONIGHT WILL BRING OUR MILD TEMPERATURES
DOWN EVEN THOUGH WIND DIRECTIONS MAY BE ESSENTIALLY WEST TO EAST
HAVING CRESTED THE APPALACHIANS BEFORE THE LEADING EDGE OF HIGH
PRESSURE ARRIVES. MINIMUMS THEREFOR IN THE MIDDLE TO UPPER 50S
THE COAST AND A CHILLIER MIDDLE UPPER 40S ACROSS OUR FAR INTERIOR.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 230 PM SATURDAY...THE SHORT TERM FORECAST IS RATHER STRAIGHT FORWARD AS
THE MID LEVEL TROUGH WILL CONTINUE TO MOVE OFFSHORE SUNDAY WITH A
MODEST NORTHWEST FLOW ENSUING THROUGH THE REMAINDER OF THE PERIOD.
AT THE SURFACE...HIGH PRESSURE BUILDS IN FROM THE NORTHWEST THEN THE
SURFACE PATTERN SHOWS A WEAKNESS DEVELOPING LATER MONDAY. ALTHOUGH
THERE ARE WEAK SHORTWAVES IN THE FLOW...NONE ARE STRONG ENOUGH TO
REINFORCE THE MODEST COLD AIR ADVECTION THAT MOVES IN SUNDAY.
OVERALL GUIDANCE REMAINS IN GOOD AGREEMENT WITH HIGHS IN THE 50S AND
LOWS IN THE 30S.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 300 PM SATURDAY...ZONAL FLOW ON TUESDAY EVEN AS IMPRESSIVE JET
OF 100KT DIVES ACROSS NRN PLAINS. THE MID LEVEL WAVE WRAPS UP FAIRLY
QUICKLY AND THUS DOES NOT LEAD TO A VERY DEEP TROUGH. EVEN SO IT
WILL MANAGE TO PUSH A RAIN-FREE COLD FRONT THROUGH THE CAROLINAS
TUESDAY NIGHT. HIGH RISES ALREADY UNDERWAY THOUGH WEDNESDAY MORNING
AS THE SYSTEM ALOFT SWINGS NEGATIVE AND LIFTS INTO NEW ENGLAND.
WEDNESDAY IS WHEN SURFACE PRESSURE GRADIENT FINALLY BECOMES LESS
NOISY AS HIGH PRESSURE CONGEALS OVER THE NC SOUNDS WHILE SUBTLE MID
LEVEL HEIGHT RISES CONTINUE. SURFACE RIDGE MOVES CONSIDERABLY TO THE
EAST FOR THE LATE WEEK PERIOD AND MID LEVEL TROUGHINESS DEVELOPS
OVER THE SWRN U.S. BOUNDARY LAYER WARMTH AND MOISTURE WILL BE ON THE
RISE BUT NOT SUFFICIENTLY FOR ANY MEANINGFUL RAIN CHANCES.
&&
.AVIATION /00Z SATURDAY THROUGH THURSDAY/...
AS OF 00Z...CONVECTION ONGOING WITH BRIEF PERIODS OF 1-2SM
VISIBILITY IN HEAVY SHOWERS...WITH ISOLATED EMBEDDED THUNDER. STRONG
HELICITY COUNTERED BY WEAK CAPE WILL LIKELY PRODUCE ISOLATED SEVERE
WEATHER. MOST OF THE ACTIVITY WILL BE OVER BY 03Z. THE HRRR HAS A
SECONDARY LINE MOVING FROM WEST TO EAST ALONG THE FRONT...BUT THE
AREA IS WEAKER THAN THE EARLIER MAIN LINE. LOOK FOR BRIEF BOUTS OF
IFR STRATUS. OVERNIGHT...CONDITIONS WILL IMPROVE AS THE THE FRONT
MOVES THROUGH. WINDS WILL SHIFT TO THE WEST...REMAINING ELEVATED.
SHOWERS WILL END FROM WEST TO EAST BY 06-08Z. BECOMING VFR TOWARD
MORNING...CONTINUING ON SUNDAY WITH A GUSTY NORTHWEST WIND.
EXTENDED OUTLOOK...SHOWERS LIKELY WITH PERIODS OF MVFR/IFR
CONDITIONS INTO EARLY SUNDAY. VFR DEVELOPING SUNDAY AND
PERSISTING THROUGH MID-WEEK.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 230 PM SATURDAY...DANGEROUS MARINE CONDITIONS OVERNIGHT AS A
MODERATELY STRONG COLD FRONT CROSSES THE AREA AND JACKS UP SW
WINDS IN ADVANCE THROUGH EARLY SUNDAY....WITH SW 20-30 KT LIKELY
OVER THE WATERS. A FEW GALE GUSTS BEYOND 20 NM IN WARMER WATERS
IS POSSIBLE...SUCH AS THE FRYING PAN SHOALS AREA. SEAS OF 5-9 FT
EXPECTED AND HIGHEST OFFSHORE...COMPOSED MAINLY OF LARGE S WAVES
EVERY 6-8 SECONDS. SEVERAL STRONG TSTMS ARE POSSIBLE ON THE WATERS
TONIGHT...AND WILL BE CAPABLE OF GENERATING GUSTS TO 50KT IN
ISOLATED MARINE LOCATIONS.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 230 PM SATURDAY...INITIALLY A WESTERLY FLOW WILL BE IN PLACE OVER
THE WATERS IN A RANGE OF 15-20 KNOTS. AS SUNDAY PROGRESSES...WINDS
WILL OBTAIN A MORE NORTHWESTERLY COMPONENT AND DECREASE. THE WINDS
WILL VERY GRADUALLY DIMINISH TO 10-15 KNOTS THROUGH THE REMAINDER
OF THE PERIOD. AS FOR SEAS...THE CHANGE IN FETCH WILL BE WELL
UNDERWAY EARLY WITH A FEW SIX FOOTERS REMAINING ACROSS THE OUTER
WATERS WITH A WIDE RANGE OF 2-6 FEET. SEAS WILL GRADUALLY DIMINISH
TO 2-3 FEET BY MONDAY.
LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 230 PM SATURDAY...WEST TO SOUTHWEST WINDS PICK UP AHEAD OF A
COLD FRONT ON TUESDAY. THE OFFSHORE FLOW DIRECTION BUILDS SEAS AWAY
FROM SHORE TO 3 OR 4 FT WHILE LANDMASS WAVE SHADOWING KEEPS THE
NEARSHORE WAVES CLOSER TO 2 FT. VEERING FLOW BEHIND THE BOUNDARY ON
WEDNESDAY TO SHORTEN THE PERIOD SOMEWHAT AS WAVE FACES STEEPEN BUT
LITTLE OVERALL CHANGE IN SIG WAVE HEIGHT EXPECTED. THURSDAY PUTS US
INTO A SOUTHERLY RETURN FLOW REGIME THAT WILL LAST FOR SEVERAL DAYS.
ANY BUILDING OF SEAS WILL BE GRADUAL AND LIKELY NOT OCCUR UNTIL
AFTER THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST SUNDAY FOR AMZ250-252-254-
256.
&&
$$
SYNOPSIS...SHK
NEAR TERM...MJC
SHORT TERM...SHK
LONG TERM...MBB
AVIATION...43
AREA FORECAST DISCUSSION
NWS RALEIGH NC
255 PM EST SAT DEC 14 2013
.SYNOPSIS...LOW PRESSURE AND A COLD FRONT WILL MOVE ACROSS THE
REGION TONIGHT. HIGH PRESSURE WILL THEN PROVIDE FAIR WEATHER
ACROSS OUR AREA THROUGH MUCH OF NEXT WEEK.
&&
NEAR TERM /THROUGH TONIGHT/...
AS OF 255 PM SATURDAY...
CURRENT PATTERN FEATURES A POSITIVELY TILTED L/W TROUGH MVG ACROSS
THE MIDDLE OF THE COUNTRY WITH A WELL DEFINED EMBEDDED S/W MOVING NE
ALONG THE OH RIVER VALLEY...AND ANOTHER S/W IN THE BASE OF THE L/W
TROUGH MVG ACROSS THE SRN PLAINS. A CLASSIC MILLER TYPE-B
CYCLOGENESIS PATTERN IS UNFOLDING ACROSS THE REGION ATTM WITH LOW
PRESSURE AND AN ASSOC COLD FRONT MVG ACROSS THE TN VALLEY AND
CYCLOGENESIS NOW OCCURRING OVER THE CAROLINAS WITH SEVERAL RECENT
OBS SHOWING RAPID PRESSURE FALLS FROM NORTHCENTRAL SC NEWD ACROSS
THE NC SANDHILLS AND COASTAL PLAIN. THE WEDGE BOUNDARY CONTINUES
ALONG AND WEST OF THE I-85 CORRIDOR STRENGTHENED BY ONGOING RAIN
ACROSS WESTERN PIEDMONT...WHILE THE COASTAL FRONT HAS BEEN SLOW TO
PUSH INLAND AND STILL LOCATED NEAR THE COAST. MEANWHILE...A LARGE
PRECIP SHIELD ASSOC WITH THE ADVANCING SHORT WAVES AND PREFRONTAL
TROUGH HAS CROSSED THE MOUNTAINS AND IS WELL-DEPICTED BY NEAR-TERM
GUIDANCE AND PROGGED TO CONTINUE MOVING ACROSS OUR CWA THROUGH THIS
EVENING INTO THE EARLY OVERNIGHT HOURS. THE HEAVIEST RAIN IS
EXPECTED TO OCCUR ACROSS OUR WESTERN ZONES AND THE TRIAD REGION
BETWEEN NOW AND 22Z...ACROSS OUR CENTRAL ZONES AND THE TRIANGLE
REGION BETWEEN 21Z AND 00Z...AND ACROSS OUR COASTAL PLAIN ZONES
BETWEEN 23Z AND 03Z.
THE PRIMARY CONCERN FOR THIS EVENING IS THE POTENTIAL FOR THUNDER.
WHILE PRESSURE IS FALLING RAPIDLY ATTM ACROSS THE SANDHILLS AND
COASTAL PLAIN REGION...AND THE SFC LOW IS EXPECTED TO MOVE NE ALONG
OR TO THE EAST OF THE I-95 CORRIDOR...THE AIRMASS WITH THE BEST
BUOYANCY IS STILL S/E OF THE COASTAL FRONT. AS PRESSURES CONTINUE TO
FALL AND THE LOW FURTHER DEVELOPS...WE MAY YET SEE AN INLAND
ADVANCEMENT OF THIS BOUNDARY. HOWEVER...THE CURRENT PRESSURE FALLS
AND SFC TEMP/WIND OBS SUGGEST THAT THE BEST TEMP/DWPT ADVECTION (AND
THUS INSTABILITY) SHOULD REMAIN MOSTLY EAST OF OUR CWA. AS SUCH...
RIGHT NOW THE BEST CHANCE FOR THUNDER IN OUR CWA APPEARS TO BE
ACROSS OUR FAR E/SE ZONES. PRIMARY IMPACTS WITH TSTMS ACROSS OUR
AREA SHOULD BE LIMITED TO SCATTERED HEAVY DOWNPOURS AND PERHAPS A
BRIEF WIND GUST OR TWO BELOW SVR LIMITS. NONETHELESS...THESE
SCATTERED HEAVIER DOWNPOURS MAY RESULT IN BRIEF PERIODS OF LOW
VISIBILITY AND WATER PONDING IN THE TYPICAL POOR DRAINAGE AREAS.
WHILE THE STEADY PRECIP IS EXPECTED TO END ACROSS OUR WESTERN ZONES
BY 02-03Z AND OUR EASTERN ZONES BY 05-06Z...LATEST HRRR SHOWS SOME
LIGHT PRECIP REDEVELOPMENT ASSOC WITH SFC FRONT AFT MIDNIGHT...SO
WILL KEEP A LINGERING 20-40 PERCENT POP GOING OVERNIGHT THROUGH 09Z.
IN ADDITION...FORECAST SOUNDINGS CONTINUE TO SHOW THE SFC NEARLY
SATURATED WITH LIGHT WINDS...THUS LOOK FOR LOW CLOUDS AND SOME FOG
TO PERSIST THROUGH SUNRISE. LOWS TONIGHT WILL RANGE FROM THE MID 30S
NW TO MID 40S SE.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 255 PM SATURDAY...
AFTER SUNRISE SUNDAY...SKIES WILL BEGIN TO CLEAR OUT AS NW LOW LEVEL
FLOW INCREASES BEHIND THE DEPARTING LOW AND BL MIXING HELPS TO DRY
OUT THE AIRMASS. AS MIXING INCREASES THROUGH THE MORNING...WE MAY
SEE A FEW HOURS OF 15-20 MPH WIND GUSTS FROM THE NW. OTHERWISE...
LOOK FOR PLENTY OF SUNSHINE...WITH HIGHS NEAR SEASONAL VALUES IN THE
LOW-MID 50S.
MAINLY CLEAR SKIES AND LIGHT WINDS WILL PROMOTE GOOD RADIATIONAL
COOLING SUNDAY NIGHT. LOWS WILL RANGE FROM THE UPPER 20S NW TO LOWER
30S E...A FEW DEGREES BELOW NORMAL.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
AS OF 235 PM SATURDAY...
A LOW PRESSURE SYSTEM DIVING OUT OF THE CANADIAN ROCKIES WILL
APPROACH THE GREAT LAKES AND DIVE THROUGH NEW ENGLAND AS AN UPPER
LEVEL TROUGH DIGS DOWN THE EASTERN SEABOARD BUT WILL HAVE A HARD
TIME EXTENDING SOUTHWARD. THIS WILL MAKE UPPER LEVEL FLOW MORE ZONAL
OVER NORTH CAROLINA CAUSING A FAIRLY CONSTANT TEMPERATURE PATTERN
WITH SOME OSCILLATION IN HIGH AND LOW TEMPS FOR THE FIRST TWO THIRDS
OF THE PERIOD. BY THE END OF THE WEEK A FEW SHORTWAVES DEVELOP IN
THE SOUTHERN STREAM AND STRONG WARM AIR ADVECTION TAKES TEMPERATURES
WELL ABOVE SEASONAL NORMALS FOR FRIDAY AND SATURDAY BEFORE A
STRONGER LOW DEVELOPS AND MOVES THROUGH THE OHIO VALLEY ON SUNDAY.
MONDAY AND TUESDAY: WHILE MODELS GENERALLY KEEP THE PATTERN THE SAME
...THE GFS HAS A BROADER SURFACE HIGH OVER THE REGION...THUS
SHUTTING OFF ANY SLIGHT COLD AIR ADVECTION ON THE FRONT SIDE OF THE
HIGH. THE ECMWF HANGS BACK WITH THIS AND THUS ITS TEMPERATURES ARE
COOLER. EITHER WAY A SLIGHT WARMING TREND FROM MONDAY TO TUESDAY
WITH UPPER 40S TO LOW 50S EXPECTED MONDAY AND MID 50S ON TUESDAY.
DRY AND MOSTLY CLEAR WITH VERY LIGHT WINDS OUT OF THE NORTHWEST.
LOWS IN THE LOWER TO MID 30S.
WEDNESDAY AND THURSDAY: A MORE NORTHWESTERLY UPPER LEVEL FLOW AND A
TIGHTER GRADIENT IN THE GFS YIELD SOME LOWER TEMPERATURES FOR
WEDNESDAY BUT THE PATTERN IS MORE RELAXED IN THE LATEST EUROPEAN
WITH MOST OF THE STRONGER DYNAMICS WELL TO THE NORTH. WILL INDICATE
A SMALL REDUCTION IN HIGHS ON WEDNESDAY...LOWER TO MID 50S WITH LOWS
IN THE LOWER 30S THURSDAY MORNING. ON THURSDAY UPPER LEVEL FLOW WILL
BEGIN TO BACK AROUND TO WESTERLY AND THEN SOUTHWESTERLY. AT THE SAME
TIME THE SURFACE HIGH MOVES OFF SHORT. THIS WILL BEGIN A PERIOD OF
SIGNIFICANT WARM AIR ADVECTION WHICH WILL PUT HIGHS ON THURSDAY INTO
THE MID TO UPPER 50S WITH LOWS IN THE LOWER 40S.
FRIDAY AND SATURDAY: AS FLOW BECOMES MORE SOUTHWESTERLY...INCREASED
WARM AIR ADVECTION WILL HELP TEMPERATURES RISE ABOVE SEASONAL
NORMALS. INCREASED MOISTURE AHEAD OF A DEVELOPING FRONTAL ZONE IN
THE TN VALLEY WILL BEGIN TO BRING MORE CLOUDS INTO THE AREA AND A
SLIGHT CHANCE OF SOME DRIZZLE OR LIGHT RAIN FRIDAY AFTERNOON AND
EVENING...INCREASING TO CHANCE OF RAIN BY SATURDAY. HIGHEST
POTENTIAL FOR RAIN WILL BE IN THE NORTHWEST. HIGHS POTENTIALLY
RISING TO THE MID TO UPPER 60S BY SATURDAY...ALMOST 15 DEGREES ABOVE
NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 100 PM SATURDAY...
AVIATION CONDITIONS WILL CONTINUE TO DETERIORATE THE REMAINDER OF
THIS AFTERNOON AS THE MAIN RAIN SHIELD TO OUR WEST CONTINUES TO MOVE
EAST. LOOK FOR WIDESPREAD LOW-MVFR AND IFR CONDITIONS (ISOLD POCKETS
OF LIFR) TO DEVELOP ACROSS MOST OF CENTRAL NC BETWEEN NOW AND 21Z.
THE RAIN IS EXPECTED TO END FROM WEST TO EAST BETWEEN 03Z-06Z AS THE
FRONT MOVES THROUGH AND LOW PRESSURE EXITS TO OUR E/NE. HOWEVER IFR
CONDITIONS WITH LOW CLOUDS AND FOG MAY PERSIST FOR THE REMAINDER OF
THE NIGHT DUE TO LINGERING LOW LEVEL MOISTURE. AFTER SUNRISE...LOOK
FOR FLIGHT CONDITIONS TO IMPROVE TO VFR AS WINDS BECOME NW AND DRIER
AIR MOVES INTO THE REGION...RESULTING IN CLEARING SKIES.
OTHERWISE...LOW LEVEL WIND SHEAR MAY STILL POSE A THREAT TO AVIATORS
THROUGH THIS EVENING AS SURFACE WINDS FROM THE EAST AT SPEEDS LESS
THAN 12 KTS ARE TOPPED BY 30-40 KT WINDS AROUND 2000 FT AGL FROM THE
SOUTH. HOWEVER...THIS CONCERN HAS BEEN DIMINISHING SOME DURING THE
PAST FEW HOURS AS LOCAL WVPS HAVE BEEN SHOWING SPEEDS AROUND 2K FT
WEAKENING JUST A BIT.
LOOKING BEYOND 18Z SUNDAY...VFR CONDITIONS EXPECTED THROUGH MID-
WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
SYNOPSIS...NP
NEAR TERM...NP
SHORT TERM...NP
LONG TERM...ELLIS
AVIATION...NP
AREA FORECAST DISCUSSION
NWS RALEIGH NC
237 PM EST SAT DEC 14 2013
.SYNOPSIS...A STORM SYSTEM WILL TRACK FROM THE SOUTHERN MISSISSIPPI
VALLEY NORTHEAST ACROSS THE CAROLINAS AND MID ATLANTIC REGION
THROUGH THE WEEKEND. HIGH PRESSURE WILL BUILD IN FROM THE SOUTHWEST
LATE SUNDAY THROUGH TUESDAY.
&&
.NEAR TERM /TODAY THROUGH TONIGHT/... AS OF 1055 AM SATURDAY...
LATEST REGIONAL ANALYSIS SHOWS A WARM FRONT ALONG THE COAST
GRADUALLY MOVING ONSHORE. LIGHT RAIN SHOWERS HAVE BEEN FORMING ALONG
THIS BOUNDARY AND MOVING INLAND AND NORTH ACROSS THE SOUTHERN
COASTAL PLAIN. FARTHER WEST...A LARGE SHIELD OF LIGHT TO MODERATE
RAIN...ASSOCIATED WITH THE LARGER SYNOPTIC SCALE TROUGH AND COMPLEX
SFC LOW PATTERN...IS STEADILY MOVING EWD ACROSS THE MOUNTAINS AND
APPROACHING THE WESTERN PIEDMONT. A TYPICAL WEDGE FRONT HAS BEEN
TAKIN SHAPE THE PAST FEW HOURS AND IS GENERALLY POSITIONED ACROSS
THE ERN FOOTHILLS/WRN PIEDMONT ATTM. THE NEAR-TERM MODELS SUCH AS
THE RAP AND HRRR HAVE A FAIRLY GOOD HANDLE ON THE PATTERN AND
REFLECT OUR CONCEPTUAL IDEA FOR THE REST OF TODAY. LOOK FOR THE RAIN
TO OUR W TO CONTINUE TO MOVE E AND EXPAND ACROSS OUR CWA AS THE DAY
PROGRESSES AS THE LARGER SCALE SYSTEM CONTINUES TO DRIFT E. THE
AFOREMENTIONED RAIN SHOULD FURTHER STRENGTHEN THE LOW LEVEL WEDGE
AND ASSOC BOUNDARY ACROSS WESTERN PIEDMONT...SO TEMPS THERE NOT
EXPECTED TO INCREASE MUCH FROM CURRENT READINGS IN THE U30S TO L40S.
MEANWHILE...THE WARM FRONT FARTHER EAST IS EXPECTED TO GRADUALLY
PUSH INLAND...WITH TEMPS ACROSS OUR E/SE ZONES CLIMBING THROUGH THE
50S AS THE AFTERNOON PROGRESSES. IN BETWEEN THESE TWO BOUNDARIES
ACROSS OUR CNTRL ZONES...TEMPS EXPECTED TO ONLY SLOWLY RISE INTO THE
UPPER 40S TO PERHAPS LOWER 50S.
IN TERMS OF PRECIP...AS ELUDED TO...THE STEADIER LIGHT/MOD PRECIP
ENTERING OUR WRN ZONES WILL CONTINUE TO GRADUALLY SPREAD EWD...SO
THROUGH EARLY AFTERNOON...LOOK FOR RAIN TO BECOME DEVELOP AND BECOME
STEADY ACROSS OUR FAR W/NW ZONES (TRIAD)...WHILE FURTHER E...THE
RAIN WILL BE MORE SCATTERED AND SHOWERY IN NATURE. THEN LATER THIS
AFTERNOON...LOOK FOR THE RAIN TO BECOME STEADY ACROSS MUCH OF OUR
CWA AS THE LOW LEVEL JET AND LARGER SCALE FORCING CURRENTLY TO OUR W
SHIFTS E ACROSS OUR AREA. BY THIS EVENING...THE PRECIP ACROSS OUR
ERN ZONES MAY BECOME MORE CONVECTIVE IN NATURE WITH THE POTENTIAL
FOR A FEW HEAVIER DOWNPOURS AS THE AFOREMENTIONED LOW LEVEL JET AND
LARGER SYNOP SCALE FORCING ENCOUNTERS THE COASTAL BOUNDARY WHICH
SHOULD BE POSITIONED SOMEWHERE ALONG OR TO THE EAST OF I-95 BY THAT
TIME. FORECAST SOUNDINGS HOWEVER SHOW WHAT LITTLE INSTABILITY THERE
IS TO BE ELEVATED...SO IMPACTS W/CONVECTION...AT LEAST AS IT APPEARS
AT THIS POINT...SHOULD BE LIMITED TO SCATTERED HEAVY DOWNPOURS AND
PERHAPS A BRIEF WIND GUST OR TWO BELOW SVR LIMITS. NONETHELESS...
THESE SCATTERED HEAVIER DOWNPOURS MAY RESULT IN BRIEF PERIODS OF LOW
VISIBILITY AND WATER PONDING IN THE TYPICAL POOR DRAINAGE AREAS.
PRECIP EXPECTED TO END ACROSS OUR WRN ZONES BY 8 PM OR SO...AND
ACROSS OUR ERN ZONES SHORTLY AFT MIDNIGHT. -NP
WILL TAPER DOWN POPS WNW TO ESE LATE TONIGHT. MODEL SOUNDINGS SHOW
THE LOW LEVELS REMAINING VERY MOIST AND STABLE... SO EXPECT LOW
CLOUDS AND FOG TO HOLD IN INTO THE OVERNIGHT HOURS... BEFORE FINALLY
LIFTING AND MIXING OUT AS THE SYSTEM CONGEALS INTO A SINGLE LOW JUST
OFF NYC TOWARD SUNRISE SUNDAY. LOWS FROM 33 NW TO 47 SE. -GIH
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM SATURDAY...
AFTER SOME MORNING CLOUDINESS ASSOCIATED WITH THE WEAK SURFACE
TROUGH TRAILING FROM THE COASTAL LOW OFF NYC... THE ENSUING
DOWNSLOPE LOW LEVEL FLOW WILL HELP DRY OUT THE LOWER TROPOSPHERE...
AS INCREASING DEEP LAYER SUBSIDENCE IN THE WAKE OF THE DEPARTING
BROAD TROUGH AXIS HELPS DRY AND STABILIZE THE MID-UPPER LEVELS.
EXPECT PLENTY OF SUNSHINE BY THE AFTERNOON HOURS. THICKNESSES DO
FALL DURING THE DAY (MUCH OF WHICH IS A FUNCTION OF COOLING AT 925-
850 MB WITH A MORE TYPICAL DIURNAL TREND NOTED BELOW 925 MB ALBEIT
WITH SHALLOW MIXING)... BUT THE INCOMING AIR MASS IS MODIFIED AND
SOURCED FROM OUR WSW... AND LATE-DAY THICKNESSES ARE STILL JUST
SLIGHTLY BELOW NORMAL. HIGHS 51-57... CLOSE TO SEASONAL NORMALS.
LOWS 26-33 AS A PORTION OF THE SURFACE HIGH NOSES IN FROM THE SW
CAUSING WINDS TO BECOME LIGHT WITH MOSTLY CLEAR SKIES FACILITATING
RADIATIONAL COOLING. -GIH
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
AS OF 235 PM SATURDAY...
A LOW PRESSURE SYSTEM DIVING OUT OF THE CANADIAN ROCKIES WILL
APPROACH THE GREAT LAKES AND DIVE THROUGH NEW ENGLAND AS AN UPPER
LEVEL TROUGH DIGS DOWN THE EASTERN SEABOARD BUT WILL HAVE A HARD
TIME EXTENDING SOUTHWARD. THIS WILL MAKE UPPER LEVEL FLOW MORE ZONAL
OVER NORTH CAROLINA CAUSING A FAIRLY CONSTANT TEMPERATURE PATTERN
WITH SOME OSCILLATION IN HIGH AND LOW TEMPS FOR THE FIRST TWO THIRDS
OF THE PERIOD. BY THE END OF THE WEEK A FEW SHORTWAVES DEVELOP IN
THE SOUTHERN STREAM AND STRONG WARM AIR ADVECTION TAKES TEMPERATURES
WELL ABOVE SEASONAL NORMALS FOR FRIDAY AND SATURDAY BEFORE A
STRONGER LOW DEVELOPS AND MOVES THROUGH THE OHIO VALLEY ON SUNDAY.
MONDAY AND TUESDAY: WHILE MODELS GENERALLY KEEP THE PATTERN THE SAME
...THE GFS HAS A BROADER SURFACE HIGH OVER THE REGION...THUS
SHUTTING OFF ANY SLIGHT COLD AIR ADVECTION ON THE FRONT SIDE OF THE
HIGH. THE ECMWF HANGS BACK WITH THIS AND THUS ITS TEMPERATURES ARE
COOLER. EITHER WAY A SLIGHT WARMING TREND FROM MONDAY TO TUESDAY
WITH UPPER 40S TO LOW 50S EXPECTED MONDAY AND MID 50S ON TUESDAY.
DRY AND MOSTLY CLEAR WITH VERY LIGHT WINDS OUT OF THE NORTHWEST.
LOWS IN THE LOWER TO MID 30S.
WEDNESDAY AND THURSDAY: A MORE NORTHWESTERLY UPPER LEVEL FLOW AND A
TIGHTER GRADIENT IN THE GFS YIELD SOME LOWER TEMPERATURES FOR
WEDNESDAY BUT THE PATTERN IS MORE RELAXED IN THE LATEST EUROPEAN
WITH MOST OF THE STRONGER DYNAMICS WELL TO THE NORTH. WILL INDICATE
A SMALL REDUCTION IN HIGHS ON WEDNESDAY...LOWER TO MID 50S WITH LOWS
IN THE LOWER 30S THURSDAY MORNING. ON THURSDAY UPPER LEVEL FLOW WILL
BEGIN TO BACK AROUND TO WESTERLY AND THEN SOUTHWESTERLY. AT THE SAME
TIME THE SURFACE HIGH MOVES OFF SHORT. THIS WILL BEGIN A PERIOD OF
SIGNIFICANT WARM AIR ADVECTION WHICH WILL PUT HIGHS ON THURSDAY INTO
THE MID TO UPPER 50S WITH LOWS IN THE LOWER 40S.
FRIDAY AND SATURDAY: AS FLOW BECOMES MORE SOUTHWESTERLY...INCREASED
WARM AIR ADVECTION WILL HELP TEMPERATURES RISE ABOVE SEASONAL
NORMALS. INCREASED MOISTURE AHEAD OF A DEVELOPING FRONTAL ZONE IN
THE TN VALLEY WILL BEGIN TO BRING MORE CLOUDS INTO THE AREA AND A
SLIGHT CHANCE OF SOME DRIZZLE OR LIGHT RAIN FRIDAY AFTERNOON AND
EVENING...INCREASING TO CHANCE OF RAIN BY SATURDAY. HIGHEST
POTENTIAL FOR RAIN WILL BE IN THE NORTHWEST. HIGHS POTENTIALLY
RISING TO THE MID TO UPPER 60S BY SATURDAY...ALMOST 15 DEGREES ABOVE
NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 100 PM SATURDAY...
AVIATION CONDITIONS WILL CONTINUE TO DETERIORATE THE REMAINDER OF
THIS AFTERNOON AS THE MAIN RAIN SHIELD TO OUR WEST CONTINUES TO MOVE
EAST. LOOK FOR WIDESPREAD LOW-MVFR AND IFR CONDITIONS (ISOLD POCKETS
OF LIFR) TO DEVELOP ACROSS MOST OF CENTRAL NC BETWEEN NOW AND 21Z.
THE RAIN IS EXPECTED TO END FROM WEST TO EAST BETWEEN 03Z-06Z AS THE
FRONT MOVES THROUGH AND LOW PRESSURE EXITS TO OUR E/NE. HOWEVER IFR
CONDITIONS WITH LOW CLOUDS AND FOG MAY LFRIDAY NIGHTINGER FOR THE REMAINDER OF
THE NIGHT DUE TO LINGERING LOW LEVEL MOISTURE. AFTER SUNRISE...LOOK
FOR FLIGHT CONDITIONS TO IMPROVE TO VFR AS WINDS BECOME NW AND DRIER
AIR MOVES INTO THE REGION...RESULTING IN CLEARING SKIES.
OTHERWISE...LOW LEVEL WIND SHEAR MAY STILL POSE A THREAT TO AVIATORS
THROUGH THIS EVENING AS SURFACE WINDS FROM THE EAST AT SPEEDS LESS
THAN 12 KTS ARE TOPPED BY 30-40 KT WINDS AROUND 2000 FT AGL FROM THE
SOUTH. HOWEVER...THIS CONCERN HAS BEEN DIMINISHING SOME DURING THE
PAST FEW HOURS AS LOCAL WVPS HAVE BEEN SHOWING SPEEDS AROUND 2K FT
WEAKENING JUST A BIT.
LOOKING BEYOND 18Z SUNDAY...VFR CONDITIONS EXPECTED THROUGH MID-
WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...NP/HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...ELLIS
AVIATION...NP
AREA FORECAST DISCUSSION
NWS RALEIGH NC
100 PM EST SAT DEC 14 2013
.SYNOPSIS...A STORM SYSTEM WILL TRACK FROM THE SOUTHERN MISSISSIPPI
VALLEY NORTHEAST ACROSS THE CAROLINAS AND MID ATLANTIC REGION
THROUGH THE WEEKEND. HIGH PRESSURE WILL BUILD IN FROM THE SOUTHWEST
LATE SUNDAY THROUGH TUESDAY.
&&
.NEAR TERM /TODAY THROUGH TONIGHT/... AS OF 1055 AM SATURDAY...
LATEST REGIONAL ANALYSIS SHOWS A WARM FRONT ALONG THE COAST
GRADUALLY MOVING ONSHORE. LIGHT RAIN SHOWERS HAVE BEEN FORMING ALONG
THIS BOUNDARY AND MOVING INLAND AND NORTH ACROSS THE SOUTHERN
COASTAL PLAIN. FARTHER WEST...A LARGE SHIELD OF LIGHT TO MODERATE
RAIN...ASSOCIATED WITH THE LARGER SYNOPTIC SCALE TROUGH AND COMPLEX
SFC LOW PATTERN...IS STEADILY MOVING EWD ACROSS THE MOUNTAINS AND
APPROACHING THE WESTERN PIEDMONT. A TYPICAL WEDGE FRONT HAS BEEN
TAKIN SHAPE THE PAST FEW HOURS AND IS GENERALLY POSITIONED ACROSS
THE ERN FOOTHILLS/WRN PIEDMONT ATTM. THE NEAR-TERM MODELS SUCH AS
THE RAP AND HRRR HAVE A FAIRLY GOOD HANDLE ON THE PATTERN AND
REFLECT OUR CONCEPTUAL IDEA FOR THE REST OF TODAY. LOOK FOR THE RAIN
TO OUR W TO CONTINUE TO MOVE E AND EXPAND ACROSS OUR CWA AS THE DAY
PROGRESSES AS THE LARGER SCALE SYSTEM CONTINUES TO DRIFT E. THE
AFOREMENTIONED RAIN SHOULD FURTHER STRENGTHEN THE LOW LEVEL WEDGE
AND ASSOC BOUNDARY ACROSS WESTERN PIEDMONT...SO TEMPS THERE NOT
EXPECTED TO INCREASE MUCH FROM CURRENT READINGS IN THE U30S TO L40S.
MEANWHILE...THE WARM FRONT FARTHER EAST IS EXPECTED TO GRADUALLY
PUSH INLAND...WITH TEMPS ACROSS OUR E/SE ZONES CLIMBING THROUGH THE
50S AS THE AFTERNOON PROGRESSES. IN BETWEEN THESE TWO BOUNDARIES
ACROSS OUR CNTRL ZONES...TEMPS EXPECTED TO ONLY SLOWLY RISE INTO THE
UPPER 40S TO PERHAPS LOWER 50S.
IN TERMS OF PRECIP...AS ELUDED TO...THE STEADIER LIGHT/MOD PRECIP
ENTERING OUR WRN ZONES WILL CONTINUE TO GRADUALLY SPREAD EWD...SO
THROUGH EARLY AFTERNOON...LOOK FOR RAIN TO BECOME DEVELOP AND BECOME
STEADY ACROSS OUR FAR W/NW ZONES (TRIAD)...WHILE FURTHER E...THE
RAIN WILL BE MORE SCATTERED AND SHOWERY IN NATURE. THEN LATER THIS
AFTERNOON...LOOK FOR THE RAIN TO BECOME STEADY ACROSS MUCH OF OUR
CWA AS THE LOW LEVEL JET AND LARGER SCALE FORCING CURRENTLY TO OUR W
SHIFTS E ACROSS OUR AREA. BY THIS EVENING...THE PRECIP ACROSS OUR
ERN ZONES MAY BECOME MORE CONVECTIVE IN NATURE WITH THE POTENTIAL
FOR A FEW HEAVIER DOWNPOURS AS THE AFOREMENTIONED LOW LEVEL JET AND
LARGER SYNOP SCALE FORCING ENCOUNTERS THE COASTAL BOUNDARY WHICH
SHOULD BE POSITIONED SOMEWHERE ALONG OR TO THE EAST OF I-95 BY THAT
TIME. FORECAST SOUNDINGS HOWEVER SHOW WHAT LITTLE INSTABILITY THERE
IS TO BE ELEVATED...SO IMPACTS W/CONVECTION...AT LEAST AS IT APPEARS
AT THIS POINT...SHOULD BE LIMITED TO SCATTERED HEAVY DOWNPOURS AND
PERHAPS A BRIEF WIND GUST OR TWO BELOW SVR LIMITS. NONETHELESS...
THESE SCATTERED HEAVIER DOWNPOURS MAY RESULT IN BRIEF PERIODS OF LOW
VISIBILITY AND WATER PONDING IN THE TYPICAL POOR DRAINAGE AREAS.
PRECIP EXPECTED TO END ACROSS OUR WRN ZONES BY 8 PM OR SO...AND
ACROSS OUR ERN ZONES SHORTLY AFT MIDNIGHT. -NP
WILL TAPER DOWN POPS WNW TO ESE LATE TONIGHT. MODEL SOUNDINGS SHOW
THE LOW LEVELS REMAINING VERY MOIST AND STABLE... SO EXPECT LOW
CLOUDS AND FOG TO HOLD IN INTO THE OVERNIGHT HOURS... BEFORE FINALLY
LIFTING AND MIXING OUT AS THE SYSTEM CONGEALS INTO A SINGLE LOW JUST
OFF NYC TOWARD SUNRISE SUNDAY. LOWS FROM 33 NW TO 47 SE. -GIH
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM SATURDAY...
AFTER SOME MORNING CLOUDINESS ASSOCIATED WITH THE WEAK SURFACE
TROUGH TRAILING FROM THE COASTAL LOW OFF NYC... THE ENSUING
DOWNSLOPE LOW LEVEL FLOW WILL HELP DRY OUT THE LOWER TROPOSPHERE...
AS INCREASING DEEP LAYER SUBSIDENCE IN THE WAKE OF THE DEPARTING
BROAD TROUGH AXIS HELPS DRY AND STABILIZE THE MID-UPPER LEVELS.
EXPECT PLENTY OF SUNSHINE BY THE AFTERNOON HOURS. THICKNESSES DO
FALL DURING THE DAY (MUCH OF WHICH IS A FUNCTION OF COOLING AT 925-
850 MB WITH A MORE TYPICAL DIURNAL TREND NOTED BELOW 925 MB ALBEIT
WITH SHALLOW MIXING)... BUT THE INCOMING AIR MASS IS MODIFIED AND
SOURCED FROM OUR WSW... AND LATE-DAY THICKNESSES ARE STILL JUST
SLIGHTLY BELOW NORMAL. HIGHS 51-57... CLOSE TO SEASONAL NORMALS.
LOWS 26-33 AS A PORTION OF THE SURFACE HIGH NOSES IN FROM THE SW
CAUSING WINDS TO BECOME LIGHT WITH MOSTLY CLEAR SKIES FACILITATING
RADIATIONAL COOLING. -GIH
&&
.LONG TERM /MONDAY THROUGH FRIDAY NIGHT/...
AS OF 330 AM SATURDAY...
MONDAY AND MONDAY NIGHT: THE LATEST LONG RANGE GUIDANCE CONTINUES TO
INDICATE DRY/BENIGN WEATHER THROUGH THE UPCOMING WORK WEEK...WITH
THE NEXT CHANCE FOR PRECIPITATION PERHAPS NOT UNTIL NEXT WEEKEND.
WEAK HIGH PRESSURE WILL BUILD INTO THE REGION SUN NIGHT/MON IN THE
WAKE OF A COLD FRONTAL PASSAGE...WITH HIGHS ON MONDAY COOLER THAN
SUNDAY...RANGING FROM THE UPPER 40S TO LOWER 50S. LOWS MON NIGHT IN
THE UPPER 20S TO NEAR 30F.
TUESDAY THROUGH WEDNESDAY NIGHT: EXPECT SOME DEGREE OF WARMING ON
TUE VIA SOUTHWEST LOW-LEVEL FLOW AND WARM ADVECTION ASSOC/W A
TIGHTENING MSLP/HEIGHT GRADIENT IN ADVANCE OF A POTENT SHORTWAVE AND
ATTENDANT CLIPPER LOW APPROACHING THE UPPER GREAT LAKES. THE
AFOREMENTIONED SHORTWAVE ENERGY DIGGING SOUTHEAST FROM CANADA TO THE
UPPER GREAT LAKES MON NIGHT/TUE WILL PROGRESS ACROSS THE LOWER GREAT
LAKES/NEW ENGLAND TUE NIGHT AND EARLY WED BEFORE MOVING OFFSHORE NEW
ENGLAND LATE WED. THE GFS/ECMWF GUIDANCE DIFFER ON THE AMPLITUDE OF
THIS SYSTEM...RESULTING IN SOME UNCERTAINTY W/REGARD TO MAX/MIN
TEMPERATURES ACROSS CENTRAL NC TUE/WED. THE GFS SUGGESTS A MORE
AMPLIFIED WAVE WITH STRONGER WARM ADVECTION ON TUE IN ADVANCE OF
IT...AND STRONGER COLD ADVECTION IN THE WAKE OF IT TUE NIGHT/WED...
WHILE THE ECMWF IS WEAKER AND MORE MODERATE WITH TEMPERATURES.
EITHER WAY...DRY CONDITIONS WILL PREVAIL WITH FORCING FOR ASCENT
REMAINING WELL NORTH OF THE REGION. WILL INDICATE HIGHS IN THE
MID/UPPER 50S ON TUE...LOWS IN THE MID 30S TUE NIGHT...AND HIGHS IN
THE LOWER/MID 50S ON WED.
THURSDAY THROUGH FRIDAY NIGHT...EXPECT RISING HEIGHTS ALOFT ALONG
THE EASTERN SEABOARD AND INCREASING MOISTURE ACROSS THE MID-ATLANTIC
AND CAROLINAS IN ASSOC/W A SOUTHERLY RETURN FLOW ON THE WESTERN
PERIPHERY OF OFFSHORE HIGH PRESSURE. UPSTREAM OF THE REGION...
EXPECT TROUGHING ALOFT ACROSS THE CENTRAL CONUS AND ROCKIES...WITH A
STRENGTHENING FRONTAL ZONE EXTENDING FROM THE LOWER MIDWEST
NORTHEAST INTO THE OH VALLEY BY FRI/FRI NIGHT. BOTH THE GFS/ECMWF
AGREE WELL ON THE OVERALL PATTERN...WHICH WOULD SUGGEST A WARMING
TREND ALONG WITH INCREASING CLOUD COVER OVER CENTRAL NC. AT THIS
TIME...EXPECT ANY CHANCE FOR PRECIPITATION TO REMAIN WEST OF THE
MOUNTAINS THROUGH FRIDAY NIGHT. -VINCENT
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 100 PM SATURDAY...
AVIATION CONDITIONS WILL CONTINUE TO DETERIORATE THE REMAINDER OF
THIS AFTERNOON AS THE MAIN RAIN SHIELD TO OUR WEST CONTINUES TO MOVE
EAST. LOOK FOR WIDESPREAD LOW-MVFR AND IFR CONDITIONS (ISOLD POCKETS
OF LIFR) TO DEVELOP ACROSS MOST OF CENTRAL NC BETWEEN NOW AND 21Z.
THE RAIN IS EXPECTED TO END FROM WEST TO EAST BETWEEN 03Z-06Z AS THE
FRONT MOVES THROUGH AND LOW PRESSURE EXITS TO OUR E/NE. HOWEVER IFR
CONDITIONS WITH LOW CLOUDS AND FOG MAY LINGER FOR THE REMAINDER OF
THE NIGHT DUE TO LINGERING LOW LEVEL MOISTURE. AFTER SUNRISE...LOOK
FOR FLIGHT CONDITIONS TO IMPROVE TO VFR AS WINDS BECOME NW AND DRIER
AIR MOVES INTO THE REGION...RESULTING IN CLEARING SKIES.
OTHERWISE...LOW LEVEL WIND SHEAR MAY STILL POSE A THREAT TO AVIATORS
THROUGH THIS EVENING AS SURFACE WINDS FROM THE EAST AT SPEEDS LESS
THAN 12 KTS ARE TOPPED BY 30-40 KT WINDS AROUND 2000 FT AGL FROM THE
SOUTH. HOWEVER...THIS CONCERN HAS BEEN DIMINISHING SOME DURING THE
PAST FEW HOURS AS LOCAL WVPS HAVE BEEN SHOWING SPEEDS AROUND 2K FT
WEAKENING JUST A BIT.
LOOKING BEYOND 18Z SUNDAY...VFR CONDITIONS EXPECTED THROUGH MID-
WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...NP/HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...VINCENT
AVIATION...NP
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1055 AM EST SAT DEC 14 2013
.SYNOPSIS...A STORM SYSTEM WILL TRACK FROM THE SOUTHERN MISSISSIPPI
VALLEY NORTHEAST ACROSS THE CAROLINAS AND MID ATLANTIC REGION
THROUGH THE WEEKEND. HIGH PRESSURE WILL BUILD IN FROM THE SOUTHWEST
LATE SUNDAY THROUGH TUESDAY.
&&
.NEAR TERM /TODAY THROUGH TONIGHT/... AS OF 1055 AM SATURDAY...
LATEST REGIONAL ANALYSIS SHOWS A WARM FRONT ALONG THE COAST
GRADUALLY MOVING ONSHORE. LIGHT RAIN SHOWERS HAVE BEEN FORMING ALONG
THIS BOUNDARY AND MOVING INLAND AND NORTH ACROSS THE SOUTHERN
COASTAL PLAIN. FARTHER WEST...A LARGE SHIELD OF LIGHT TO MODERATE
RAIN...ASSOCIATED WITH THE LARGER SYNOPTIC SCALE TROUGH AND COMPLEX
SFC LOW PATTERN...IS STEADILY MOVING EWD ACROSS THE MOUNTAINS AND
APPROACHING THE WESTERN PIEDMONT. A TYPICAL WEDGE FRONT HAS BEEN
TAKIN SHAPE THE PAST FEW HOURS AND IS GENERALLY POSITIONED ACROSS
THE ERN FOOTHILLS/WRN PIEDMONT ATTM. THE NEAR-TERM MODELS SUCH AS
THE RAP AND HRRR HAVE A FAIRLY GOOD HANDLE ON THE PATTERN AND
REFLECT OUR CONCEPTUAL IDEA FOR THE REST OF TODAY. LOOK FOR THE RAIN
TO OUR W TO CONTINUE TO MOVE E AND EXPAND ACROSS OUR CWA AS THE DAY
PROGRESSES AS THE LARGER SCALE SYSTEM CONTINUES TO DRIFT E. THE
AFOREMENTIONED RAIN SHOULD FURTHER STRENGTHEN THE LOW LEVEL WEDGE
AND ASSOC BOUNDARY ACROSS WESTERN PIEDMONT...SO TEMPS THERE NOT
EXPECTED TO INCREASE MUCH FROM CURRENT READINGS IN THE U30S TO L40S.
MEANWHILE...THE WARM FRONT FARTHER EAST IS EXPECTED TO GRADUALLY
PUSH INLAND...WITH TEMPS ACROSS OUR E/SE ZONES CLIMBING THROUGH THE
50S AS THE AFTERNOON PROGRESSES. IN BETWEEN THESE TWO BOUNDARIES
ACROSS OUR CNTRL ZONES...TEMPS EXPECTED TO ONLY SLOWLY RISE INTO THE
UPPER 40S TO PERHAPS LOWER 50S.
IN TERMS OF PRECIP...AS ELUDED TO...THE STEADIER LIGHT/MOD PRECIP
ENTERING OUR WRN ZONES WILL CONTINUE TO GRADUALLY SPREAD EWD...SO
THROUGH EARLY AFTERNOON...LOOK FOR RAIN TO BECOME DEVELOP AND BECOME
STEADY ACROSS OUR FAR W/NW ZONES (TRIAD)...WHILE FURTHER E...THE
RAIN WILL BE MORE SCATTERED AND SHOWERY IN NATURE. THEN LATER THIS
AFTERNOON...LOOK FOR THE RAIN TO BECOME STEADY ACROSS MUCH OF OUR
CWA AS THE LOW LEVEL JET AND LARGER SCALE FORCING CURRENTLY TO OUR W
SHIFTS E ACROSS OUR AREA. BY THIS EVENING...THE PRECIP ACROSS OUR
ERN ZONES MAY BECOME MORE CONVECTIVE IN NATURE WITH THE POTENTIAL
FOR A FEW HEAVIER DOWNPOURS AS THE AFOREMENTIONED LOW LEVEL JET AND
LARGER SYNOP SCALE FORCING ENCOUNTERS THE COASTAL BOUNDARY WHICH
SHOULD BE POSITIONED SOMEWHERE ALONG OR TO THE EAST OF I-95 BY THAT
TIME. FORECAST SOUNDINGS HOWEVER SHOW WHAT LITTLE INSTABILITY THERE
IS TO BE ELEVATED...SO IMPACTS W/CONVECTION...AT LEAST AS IT APPEARS
AT THIS POINT...SHOULD BE LIMITED TO SCATTERED HEAVY DOWNPOURS AND
PERHAPS A BRIEF WIND GUST OR TWO BELOW SVR LIMITS. NONETHELESS...
THESE SCATTERED HEAVIER DOWNPOURS MAY RESULT IN BRIEF PERIODS OF LOW
VISIBILITY AND WATER PONDING IN THE TYPICAL POOR DRAINAGE AREAS.
PRECIP EXPECTED TO END ACROSS OUR WRN ZONES BY 8 PM OR SO...AND
ACROSS OUR ERN ZONES SHORTLY AFT MIDNIGHT. -NP
WILL TAPER DOWN POPS WNW TO ESE LATE TONIGHT. MODEL SOUNDINGS SHOW
THE LOW LEVELS REMAINING VERY MOIST AND STABLE... SO EXPECT LOW
CLOUDS AND FOG TO HOLD IN INTO THE OVERNIGHT HOURS... BEFORE FINALLY
LIFTING AND MIXING OUT AS THE SYSTEM CONGEALS INTO A SINGLE LOW JUST
OFF NYC TOWARD SUNRISE SUNDAY. LOWS FROM 33 NW TO 47 SE. -GIH
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM SATURDAY...
AFTER SOME MORNING CLOUDINESS ASSOCIATED WITH THE WEAK SURFACE
TROUGH TRAILING FROM THE COASTAL LOW OFF NYC... THE ENSUING
DOWNSLOPE LOW LEVEL FLOW WILL HELP DRY OUT THE LOWER TROPOSPHERE...
AS INCREASING DEEP LAYER SUBSIDENCE IN THE WAKE OF THE DEPARTING
BROAD TROUGH AXIS HELPS DRY AND STABILIZE THE MID-UPPER LEVELS.
EXPECT PLENTY OF SUNSHINE BY THE AFTERNOON HOURS. THICKNESSES DO
FALL DURING THE DAY (MUCH OF WHICH IS A FUNCTION OF COOLING AT 925-
850 MB WITH A MORE TYPICAL DIURNAL TREND NOTED BELOW 925 MB ALBEIT
WITH SHALLOW MIXING)... BUT THE INCOMING AIR MASS IS MODIFIED AND
SOURCED FROM OUR WSW... AND LATE-DAY THICKNESSES ARE STILL JUST
SLIGHTLY BELOW NORMAL. HIGHS 51-57... CLOSE TO SEASONAL NORMALS.
LOWS 26-33 AS A PORTION OF THE SURFACE HIGH NOSES IN FROM THE SW
CAUSING WINDS TO BECOME LIGHT WITH MOSTLY CLEAR SKIES FACILITATING
RADIATIONAL COOLING. -GIH
&&
.LONG TERM /MONDAY THROUGH FRIDAY NIGHT/...
AS OF 330 AM SATURDAY...
MONDAY AND MONDAY NIGHT: THE LATEST LONG RANGE GUIDANCE CONTINUES TO
INDICATE DRY/BENIGN WEATHER THROUGH THE UPCOMING WORK WEEK...WITH
THE NEXT CHANCE FOR PRECIPITATION PERHAPS NOT UNTIL NEXT WEEKEND.
WEAK HIGH PRESSURE WILL BUILD INTO THE REGION SUN NIGHT/MON IN THE
WAKE OF A COLD FRONTAL PASSAGE...WITH HIGHS ON MONDAY COOLER THAN
SUNDAY...RANGING FROM THE UPPER 40S TO LOWER 50S. LOWS MON NIGHT IN
THE UPPER 20S TO NEAR 30F.
TUESDAY THROUGH WEDNESDAY NIGHT: EXPECT SOME DEGREE OF WARMING ON
TUE VIA SOUTHWEST LOW-LEVEL FLOW AND WARM ADVECTION ASSOC/W A
TIGHTENING MSLP/HEIGHT GRADIENT IN ADVANCE OF A POTENT SHORTWAVE AND
ATTENDANT CLIPPER LOW APPROACHING THE UPPER GREAT LAKES. THE
AFOREMENTIONED SHORTWAVE ENERGY DIGGING SOUTHEAST FROM CANADA TO THE
UPPER GREAT LAKES MON NIGHT/TUE WILL PROGRESS ACROSS THE LOWER GREAT
LAKES/NEW ENGLAND TUE NIGHT AND EARLY WED BEFORE MOVING OFFSHORE NEW
ENGLAND LATE WED. THE GFS/ECMWF GUIDANCE DIFFER ON THE AMPLITUDE OF
THIS SYSTEM...RESULTING IN SOME UNCERTAINTY W/REGARD TO MAX/MIN
TEMPERATURES ACROSS CENTRAL NC TUE/WED. THE GFS SUGGESTS A MORE
AMPLIFIED WAVE WITH STRONGER WARM ADVECTION ON TUE IN ADVANCE OF
IT...AND STRONGER COLD ADVECTION IN THE WAKE OF IT TUE NIGHT/WED...
WHILE THE ECMWF IS WEAKER AND MORE MODERATE WITH TEMPERATURES.
EITHER WAY...DRY CONDITIONS WILL PREVAIL WITH FORCING FOR ASCENT
REMAINING WELL NORTH OF THE REGION. WILL INDICATE HIGHS IN THE
MID/UPPER 50S ON TUE...LOWS IN THE MID 30S TUE NIGHT...AND HIGHS IN
THE LOWER/MID 50S ON WED.
THURSDAY THROUGH FRIDAY NIGHT...EXPECT RISING HEIGHTS ALOFT ALONG
THE EASTERN SEABOARD AND INCREASING MOISTURE ACROSS THE MID-ATLANTIC
AND CAROLINAS IN ASSOC/W A SOUTHERLY RETURN FLOW ON THE WESTERN
PERIPHERY OF OFFSHORE HIGH PRESSURE. UPSTREAM OF THE REGION...
EXPECT TROUGHING ALOFT ACROSS THE CENTRAL CONUS AND ROCKIES...WITH A
STRENGTHENING FRONTAL ZONE EXTENDING FROM THE LOWER MIDWEST
NORTHEAST INTO THE OH VALLEY BY FRI/FRI NIGHT. BOTH THE GFS/ECMWF
AGREE WELL ON THE OVERALL PATTERN...WHICH WOULD SUGGEST A WARMING
TREND ALONG WITH INCREASING CLOUD COVER OVER CENTRAL NC. AT THIS
TIME...EXPECT ANY CHANCE FOR PRECIPITATION TO REMAIN WEST OF THE
MOUNTAINS THROUGH FRIDAY NIGHT. -VINCENT
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 650 AM SATURDAY...
HIGH CONFIDENCE IN DETERIORATING AVIATION CONDITIONS FROM WEST TO
EAST STARTING THIS MORNING AFTER 14Z. CURRENT CONDITIONS OVER
CENTRAL NC ARE GOOD WITH VFR VSBYS/SKIES... BUT AS A STRONG STORM
SYSTEM NOW OVER AR/LA TRACKS EASTWARD THEN NORTHEAST... CROSSING THE
DEEP SOUTH TOWARD THE CAROLINAS EARLY THIS MORNING THROUGH
TONIGHT... RAPID SATURATION WILL CAUSE CIGS/VSBYS TO DROP TO MVFR BY
13Z-17Z (FROM WRN TO ERN TAFS) IN WIDESPREAD RAIN... AND TO IFR FROM
17Z-21Z (WRN TO ERN TAFS)... OCCASIONALLY DROPPING TO LIFR. THESE
POOR AVIATION CONDITIONS WILL LAST THROUGH SUNSET. RAIN WILL END
WEST TO EAST BETWEEN 03Z AND 08Z AS THE FRONTAL SYSTEM MOVES
THROUGH... BUT IFR/LIFR CIGS/VSBYS IN FOG ARE LIKELY TO PERSIST
UNTIL AROUND 12Z... WHEN SURFACE WINDS BECOME FROM THE WEST OR WNW
LEADING TO THE ONSET OF DOWNSLOPE FLOW. LOW LEVEL WIND SHEAR WILL
POST A THREAT TO AVIATORS THROUGH TODAY AS SURFACE WINDS FROM THE
EAST OR ESE UNDER 12 KTS ARE TOPPED BY 30-40 KT WINDS AROUND 2000 FT
AGL FROM THE SW. THIS MAY CAUSE SIGNIFICANT HANDLING DIFFICULTY AND
MECHANICAL TURBULENCE FROM 14Z THROUGH 05Z.
LOOKING BEYOND 12Z SUNDAY MORNING... EXPECT RISING CIGS/VSBYS TO VFR
THROUGH 14Z. VFR CONDITIONS LIKELY TO HOLD FROM MIDDAY SUN THROUGH
WED AS HIGH PRESSURE BUILDS IN FROM THE SW. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...NP/HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...VINCENT
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
949 PM CST SUN DEC 15 2013
.UPDATE...
ISSUED AT 949 PM CST SUN DEC 15 2013
MAIN UPDATE CONCERN WAS INCREASING WINDS LATE TONIGHT INTO MONDAY
AND POSSIBLY SOME MIXED PRECIPITATION. 16 DEC 00 UTC NAM SOUNDINGS
SHOW QUITE A BIT OF WARM AIR ALOFT LATEST HRRR CONTINUES TO
INDICATE A BAND OF LIGHT PRECIPITATION MOVING NORTHWEST TO
SOUTHEAST ACROSS THE AREA LATE TONIGHT. IF THIS DEVELOPS...NAM
SOUNDINGS INDICATE A POSSIBILITY OF FREEZING RAIN OR SLEET. AS YOU
GET INTO EASTERN PORTIONS OF CENTRAL NORTH DAKOTA IT MAY REMAIN
COLD ENOUGH FOR ALL SNOW. PRECIPITATION SHOULD REMAIN LIGHT SO AT
THIS TIME AM NOT ANTICIPATING ANY ADVISORY. WILL MENTION THE
POSSIBILITY OF MIXED PRECIPITATION IN THE UPDATED HWO. WILL ALSO
MENTION PATCHY BLOWING SNOW...MAINLY NORTH LATE TONIGHT INTO
MONDAY AS WEST WINDS INCREASE BEHIND THE WARM FRONT. UPDATED
PRODUCTS WILL BE SENT OUT SHORTLY.
UPDATE ISSUED AT 658 PM CST SUN DEC 15 2013
WILL NEED TO CONTINUE AND MONITOR TEMPERATURES THROUGH THE
EVENING. WARM FRONT REMAINS OVER WESTERN NORTH DAKOTA AND WILL
LIKELY BE A FEW MORE HOURS BEFORE IT BEGINS TO MAKE PROGRESS
EASTWARD. THUS WILL NEED TO MODIFY EVENING TEMPERATURES WITH
CENTRAL AND EASTERN AREAS STARTING OUT WITH TEMPERATURES MAINLY IN
THE SINGLE DIGITS ABOVE ZERO...WITH THE FAR EAST IN THE SINGLE
DIGITS BELOW ZERO. TEMPERATURES ARE EXPECTED TO RISE OVERNIGHT SO
THESE WILL LIKELY BE THE OVERNIGHT LOWS...UNLESS WE WOULD DROP A
FEW MORE DEGREES BEFORE TEMPERATURES BEGIN TO CLIMB.
LATEST RAP AND ESPECIALLY HRRR SEEM TO HAVE A REASONABLE HANDLE ON
THE CURRENT LIGHT SNOW OVER THE NORTHEAST CWA. UTILIZED THE HRRR
FOR SHORT TERM POPS TONIGHT. THE AREA OVER THE NORTH CENTRAL MOVES
SOUTHEAST WITH ANOTHER AREA OF LIGHT SNOW DEVELOPING OVER THE
NORTHWEST LATER THIS EVENING AND SPREADING SOUTHEAST AS THE WARM
FRONT TRACKS EAST ACROSS THE CWA.
&&
.SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON)
ISSUED AT 319 PM CST SUN DEC 15 2013
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE CHANCES FOR
LIGHT SNOW TONIGHT AND MONDAY...ALONG WITH A WARMING TREND OVER
THE NEXT 24 HOURS FOR MOST LOCATIONS.
CURRENTLY...LIGHT SNOW CONTINUES TO DIMINISH AND PUSH EAST AS
FORCING AHEAD OF A SFC TROUGH DECREASES. SKIES HAVE PARTIALLY
CLEARED WEST CENTRAL AND SOUTHWEST BEHIND THE TROUGH. LEFT EXIT
REGION OF AN UPPER LEVEL JET STREAK WILL REMAIN ALOFT AT LEAST
THROUGH TONIGHT. COUPLED WITH A WEAK MID LEVEL DISTURBANCE WILL
MAINTAIN A SLIGHT CHANCE OF LIGHT SNOW MOST LOCATIONS THROUGH 12Z
ALONG WITH CLOUDY SKIES.
WEAK CAA TONIGHT INTO MONDAY...HOWEVER WITH THE INCREASE IN MIXING
WE EXPECT THE ARCTIC AIR TO BE SCOURED OUT RESULTING IN STEADY TO
WARMING TEMPERATURES TONIGHT INTO MONDAY. HIGHS IN THE 30S WILL BE
COMMON ACROSS WEST AND CENTRAL NORTH DAKOTA MONDAY AFTERNOON.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 319 PM CST SUN DEC 15 2013
THE MAIN FORECAST ISSUE IS THE POTENTIAL FOR ANOTHER ROUND OF SNOW
AND COLDER TEMPERATURES MID TO LATE WEEK.
RELATIVELY MILD AIR WILL OVERSPREAD THE ENTIRE FORECAST AREA ON
MONDAY AND WILL CONTINUE MONDAY NIGHT THROUGH TUESDAY NIGHT. A
REINFORCEMENT OF MILD PACIFIC AIR WILL MOVE INTO THE REGION TUESDAY
NIGHT AS AN ALBERTA CLIPPER LOW PRESSURE SYSTEM MOVES FROM ALBERTA
TUESDAY AFTERNOON TO SOUTHERN MANITOBA BY WEDNESDAY MORNING...WITH A
WARM FRONT EXTENDING FROM THE LOW THAT WILL MOVE EAST ACROSS NORTH
DAKOTA TUESDAY NIGHT.
ON WEDNESDAY AN ARCTIC COLD FRONT IS FORECAST TO ENTER NORTHERN
NORTH DAKOTA LATE MORNING/NOON...AND MOVE SOUTH ACROSS THE STATE
REACHING THE SOUTH DAKOTA BORDER BY/DURING WEDNESDAY EVENING. THUS A
LARGE TEMPERATURE DIFFERENCE FROM NORTH TO SOUTH ACROSS THE STATE ON
WEDNESDAY. TEMPERATURES SHOULD REACH INTO THE TEENS TO LOWER 20S
ALONG AND AHEAD OF THE ARCTIC FRONT IN THE NORTHERN COUNTIES...AND
REACH INTO THE UPPER 20S/MID 30S SOUTHERN COUNTIES.
AS THE SURFACE ARCTIC FRONT MOVES SOUTH...AN UPPER LEVEL TROUGH WILL
DIG SOUTHWARD ACROSS THE ROCKIES/FRONT RANGE...AND THE TROUGH AXIS
AND ACCOMPANYING ENERGY IMPULSE WILL ACT TO INDUCE SNOWFALL ALONG
AND BEHIND THE ARCTIC FRONT. AT THIS TIME THE MODEL SOLUTIONS APPEAR
TO COME CLOSER TO AGREEMENT...WITH SNOWFALL IN MONTANA
WEDNESDAY...EXPANDING EASTWARD INTO NORTH DAKOTA WEDNESDAY NIGHT AND
THURSDAY...AND EXITING THE STATE TO THE EAST THURSDAY NIGHT. CURRENT
MODELS SUGGEST SOUTHERN NORTH DAKOTA AND NORTHERN SOUTH DAKOTA WOULD
BE THE TARGET FOR HIGHEST PRECIPITATION AMOUNTS.
CURRENT ESTIMATES ARE THAT IN A TIME PERIOD OF WEDNESDAY NIGHT
THROUGH THURSDAY NIGHT: 2 TO 3 INCHES OF SNOW ALONG AND SOUTH OF
INTERSTATE 94...TO AROUND 1/2 INCH ALONG THE CANADIAN BORDER.
THE ARCTIC AIR REMAINS IN PLACE THURSDAY THROUGH FRIDAY/FRIDAY
NIGHT. LOW TEMPERATURES BELOW ZERO IN THE NORTH WEDNESDAY
NIGHT...AND OVER ALL OF NORTH DAKOTA THURSDAY NIGHT...AND MOST AREAS
FRIDAY NIGHT. WIND CHILL HEADLINES MAY BE NEEDED THURSDAY NIGHT
THROUGH FRIDAY MORNING. THEN SOME MODERATION OVER THE WEEKEND - BUT
STILL BELOW AVERAGE TEMPERATURES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 949 PM CST SUN DEC 15 2013
FOR THE 06Z UTC TAF ISSUANCE...MAINLY VFR CONDITIONS TO BEGIN THE
PERIOD. A WARM FRONT IS EXPECTED TO MOVE EAST ACROSS THE AREA
TONIGHT BRINGING A BAND OF LIGHT SNOW OR POSSIBLY MIXED
PRECIPITATION...WITH OCCASIONAL MVFR CEILINGS AND VISIBILITIES
FROM WILLISTON AND MINOT LATE THIS EVENING TOWARD BISMARCK AND
JAMESTOWN LATE TONIGHT. DICKINSON MAY REMAIN OUT OF THIS BAND OF
SNOW. WINDS ARE EXPECTED TO SHIFT WESTERLY FROM WEST TO EAST
TONIGHT. WEST WINDS WILL CONTINUE ON MONDAY BECOMING GUSTY AT
TIMES IN THE AFTERNOON. EXPECT MAINLY VFR CONDITIONS ACROSS THE
AREA ON MONDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...NH
LONG TERM...JV
AVIATION...TWH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
658 PM CST SUN DEC 15 2013
.UPDATE...
ISSUED AT 658 PM CST SUN DEC 15 2013
WILL NEED TO CONTINUE AND MONITOR TEMPERATURES THROUGH THE
EVENING. WARM FRONT REMAINS OVER WESTERN NORTH DAKOTA AND WILL
LIKELY BE A FEW MORE HOURS BEFORE IT BEGINS TO MAKE PROGRESS
EASTWARD. THUS WILL NEED TO MODIFY EVENING TEMPERATURES WITH
CENTRAL AND EASTERN AREAS STARTING OUT WITH TEMPERATURES MAINLY IN
THE SINGLE DIGITS ABOVE ZERO...WITH THE FAR EAST IN THE SINGLE
DIGITS BELOW ZERO. TEMPERATURES ARE EXPECTED TO RISE OVERNIGHT SO
THESE WILL LIKELY BE THE OVERNIGHT LOWS...UNLESS WE WOULD DROP A
FEW MORE DEGREES BEFORE TEMPERATURES BEGIN TO CLIMB.
LATEST RAP AND ESPECIALLY HRRR SEEM TO HAVE A REASONABLE HANDLE ON
THE CURRENT LIGHT SNOW OVER THE NORTHEAST CWA. UTILIZED THE HRRR
FOR SHORT TERM POPS TONIGHT. THE AREA OVER THE NORTH CENTRAL MOVES
SOUTHEAST WITH ANOTHER AREA OF LIGHT SNOW DEVELOPING OVER THE
NORTHWEST LATER THIS EVENING AND SPREADING SOUTHEAST AS THE WARM
FRONT TRACKS EAST ACROSS THE CWA.
&&
.SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON)
ISSUED AT 319 PM CST SUN DEC 15 2013
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE CHANCES FOR
LIGHT SNOW TONIGHT AND MONDAY...ALONG WITH A WARMING TREND OVER
THE NEXT 24 HOURS FOR MOST LOCATIONS.
CURRENTLY...LIGHT SNOW CONTINUES TO DIMINISH AND PUSH EAST AS
FORCING AHEAD OF A SFC TROUGH DECREASES. SKIES HAVE PARTIALLY
CLEARED WEST CENTRAL AND SOUTHWEST BEHIND THE TROUGH. LEFT EXIT
REGION OF AN UPPER LEVEL JET STREAK WILL REMAIN ALOFT AT LEAST
THROUGH TONIGHT. COUPLED WITH A WEAK MID LEVEL DISTURBANCE WILL
MAINTAIN A SLIGHT CHANCE OF LIGHT SNOW MOST LOCATIONS THROUGH 12Z
ALONG WITH CLOUDY SKIES.
WEAK CAA TONIGHT INTO MONDAY...HOWEVER WITH THE INCREASE IN MIXING
WE EXPECT THE ARCTIC AIR TO BE SCOURED OUT RESULTING IN STEADY TO
WARMING TEMPERATURES TONIGHT INTO MONDAY. HIGHS IN THE 30S WILL BE
COMMON ACROSS WEST AND CENTRAL NORTH DAKOTA MONDAY AFTERNOON.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 319 PM CST SUN DEC 15 2013
THE MAIN FORECAST ISSUE IS THE POTENTIAL FOR ANOTHER ROUND OF SNOW
AND COLDER TEMPERATURES MID TO LATE WEEK.
RELATIVELY MILD AIR WILL OVERSPREAD THE ENTIRE FORECAST AREA ON
MONDAY AND WILL CONTINUE MONDAY NIGHT THROUGH TUESDAY NIGHT. A
REINFORCEMENT OF MILD PACIFIC AIR WILL MOVE INTO THE REGION TUESDAY
NIGHT AS AN ALBERTA CLIPPER LOW PRESSURE SYSTEM MOVES FROM ALBERTA
TUESDAY AFTERNOON TO SOUTHERN MANITOBA BY WEDNESDAY MORNING...WITH A
WARM FRONT EXTENDING FROM THE LOW THAT WILL MOVE EAST ACROSS NORTH
DAKOTA TUESDAY NIGHT.
ON WEDNESDAY AN ARCTIC COLD FRONT IS FORECAST TO ENTER NORTHERN
NORTH DAKOTA LATE MORNING/NOON...AND MOVE SOUTH ACROSS THE STATE
REACHING THE SOUTH DAKOTA BORDER BY/DURING WEDNESDAY EVENING. THUS A
LARGE TEMPERATURE DIFFERENCE FROM NORTH TO SOUTH ACROSS THE STATE ON
WEDNESDAY. TEMPERATURES SHOULD REACH INTO THE TEENS TO LOWER 20S
ALONG AND AHEAD OF THE ARCTIC FRONT IN THE NORTHERN COUNTIES...AND
REACH INTO THE UPPER 20S/MID 30S SOUTHERN COUNTIES.
AS THE SURFACE ARCTIC FRONT MOVES SOUTH...AN UPPER LEVEL TROUGH WILL
DIG SOUTHWARD ACROSS THE ROCKIES/FRONT RANGE...AND THE TROUGH AXIS
AND ACCOMPANYING ENERGY IMPULSE WILL ACT TO INDUCE SNOWFALL ALONG
AND BEHIND THE ARCTIC FRONT. AT THIS TIME THE MODEL SOLUTIONS APPEAR
TO COME CLOSER TO AGREEMENT...WITH SNOWFALL IN MONTANA
WEDNESDAY...EXPANDING EASTWARD INTO NORTH DAKOTA WEDNESDAY NIGHT AND
THURSDAY...AND EXITING THE STATE TO THE EAST THURSDAY NIGHT. CURRENT
MODELS SUGGEST SOUTHERN NORTH DAKOTA AND NORTHERN SOUTH DAKOTA WOULD
BE THE TARGET FOR HIGHEST PRECIPITATION AMOUNTS.
CURRENT ESTIMATES ARE THAT IN A TIME PERIOD OF WEDNESDAY NIGHT
THROUGH THURSDAY NIGHT: 2 TO 3 INCHES OF SNOW ALONG AND SOUTH OF
INTERSTATE 94...TO AROUND 1/2 INCH ALONG THE CANADIAN BORDER.
THE ARCTIC AIR REMAINS IN PLACE THURSDAY THROUGH FRIDAY/FRIDAY
NIGHT. LOW TEMPERATURES BELOW ZERO IN THE NORTH WEDNESDAY
NIGHT...AND OVER ALL OF NORTH DAKOTA THURSDAY NIGHT...AND MOST AREAS
FRIDAY NIGHT. WIND CHILL HEADLINES MAY BE NEEDED THURSDAY NIGHT
THROUGH FRIDAY MORNING. THEN SOME MODERATION OVER THE WEEKEND - BUT
STILL BELOW AVERAGE TEMPERATURES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 658 PM CST SUN DEC 15 2013
FOR THE 00Z UTC TAF ISSUANCE...MAINLY VFR CONDITIONS TO BEGIN THE
PERIOD. A WARM FRONT IS EXPECTED TO MOVE EAST ACROSS THE AREA
TONIGHT BRINGING A BAND OF LIGHT SNOW WITH OCCASIONAL MVFR
CEILINGS AND VISIBILITIES FROM WILLISTON AND MINOT LATE THIS
EVENING TOWARD BISMARCK AND JAMESTOWN LATE TONIGHT. DICKINSON MAY
REMAIN OUT OF THIS BAND OF SNOW. WINDS ARE EXPECTED TO SHIFT
WESTERLY FROM WEST TO EAST TONIGHT. WEST WINDS WILL CONTINUE ON
MONDAY BECOMING GUSTY AT TIMES IN THE AFTERNOON. EXPECT MAINLY VFR
CONDITIONS ACROSS THE AREA ON MONDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...NH
LONG TERM...JV
AVIATION...TWH
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
646 PM CST SUN DEC 15 2013
.UPDATE...
ISSUED AT 646 PM CST SUN DEC 15 2013
THE CURRENT FORECAST HAS THE RIGHT TRENDS...AND IS ON TRACK. WILL
ATTEMPT TO ADD SOME DETAIL THROUGH THE OVERNIGHT HOURS.
TEMPERATURES ALONG AND EAST OF THE VALLEY ARE NOT WARMING AS
QUICKLY AS EXPECTED...AND WILL ADJUST THESE VALUES THROUGH MONDAY
MORNING (USING A CONSENSUS OF HI-RES SHORT TERM MODELS).
THE AREA OF 850MB WARM AIR ADVECTION SNOWFALL IS NOW EAST OF THE
VALLEY. ACCUMULATION ASSOCIATED WITH THIS SNOW BAND HAS BEEN
MOSTLY JUST A TRACE OR MOSTLY FLURRIES. WILL BE WATCHING A COUPLE
UPPER WAVES UPSTREAM AS A STRONG 100+ KNOT UPPER JET MOVES INTO
THE REGION. THE HRRR AND RAP INDICATE A COUPLE WAVES THAT WILL
PROVIDE A PERIOD OF SNOWFALL...JUST NOT SURE EXACTLY WHERE. THE
FIRST AREA OF SNOWFALL IS MOVING INTO NORTHEAST NORTH DAKOTA...AND
SHOULD CONTINUE TO THE SOUTHEAST...AND INTO WEST CENTRAL MINNESOTA
BY MIDNIGHT. THE RAP AND HRRR INDICATE AN INCH OR SO OF SNOWFALL
POSSIBLE IN A NARROW BAND. INCREASED POPS TO 50% FOR THIS FEATURE
WHERE IT IS EXPECTED TO TRACK. THE NEXT WAVE IS EXPECTED TO MOVE
OUT OF NW NORTH DAKOTA AFTER 06Z...AND MOVE THROUGH THE SOUTHERN
FA AFTER 10Z. WILL MONITOR OBSERVATIONS AND INCOMING MODEL
GUIDANCE...BUT FOR NOW CONFIDENCE IS TOO LOW TO INCREASE POPS FOR
THIS FEATURE.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 302 PM CST SUN DEC 15 2013
FORECAST CHALLENGES WILL BE THE LIGHT SNOW MOVING THROUGH THE FA
TONIGHT AND THE ADVERTISED WARM UP. MODELS HAVE BEEN DOING A FAIR
JOB WITH THE LIGHT SNOW TODAY BUT TEMPS HAVE BEEN HARD TO NAIL
DOWN. AS OF MID AFTERNOON ANY LIGHT SNOW HAS MAIN STAYED WEST OF
THE RED RIVER VALLEY. CANADIAN RADARS SEEM TO SHOW SOME BETTER
ECHOES TRYING TO MOVE TOWARD THE NORTHERN VALLEY SO SOME LIGHT
SNOW SHOULD CONTINUE TO PUSH EASTWARD TONIGHT. TEMPS HAVE
STRUGGLED TO REACH 10 BELOW AT KGFK WHILE DOWN AT KBWP TEMPS HAVE
HIT ZERO. MEANWHILE THE NORTHEAST WAS MAINLY 10 BELOW TO 15
BELOW. CLOUDS WILL CONTINUE TO PUSH EASTWARD AND SHOULD HELP BRING
STEADY OR SLOWLY RISING TEMPS THERE. TRADITIONALLY DO NOT SEE GOOD
THERMAL RECOVERY IN THE WINTER WITH SNOW ON THE GROUND UNLESS
THERE IS SOME WESTERLY COMPONENT TO THE WIND. THIS DOES HAPPEN
AFTER MIDNIGHT FOR THE HIGHER ELEVATIONS ACROSS THE WESTERN FA AND
INTO THE RED RIVER VALLEY TOWARD 12Z MON.
AFOREMENTIONED BOUNDARY/WARM FRONT WILL MOVE INTO THE MN FA ON
MONDAY WITH SOME LINGERING LIGHT SNOW CHANCES WITH IT. WILL KEEP
THE WESTERN FA DRY. WILL SEE HOW WARM IT WILL ACTUALLY GET WITH SO
MUCH SNOW ON THE GROUND. PRETTY MUCH KEPT HIGHS IN THE UPPER 20S
AS HAS BEEN CONTINUITY. MODELS CONTINUE TO LINGER SOME LIGHT SNOW
IN THE EAST MON NIGHT SO MATCHED NEIGHBORS WITH SOME LIGHT SNOW
CHANCES THEN.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 302 PM CST SUN DEC 15 2013
TUE SHOULD BE DRY SO MAIN QUESTION WILL BE TEMPS. EXPECT
DECREASING WIND SPEEDS THRU THE DAY AND NOT AS MUCH OF A WESTERLY
COMPONENT. THEREFORE A BIT OF COOLER DAY BUT STILL MILD IN
COMPARISON TO RECENT DAYS. LOOKING LIKE A WEAK CLIPPER SYSTEM TUE
NIGHT INTO WED WITH ITS MAIN EFFECTS ACROSS THE NORTH.
MAIN ISSUES WILL BE THE LIGHT SNOW EVENT THURSDAY. 12Z ECMWF HAS
COME AROUND A BIT FARTHER NORTH WITH LIGHT SNOW BAND ACROSS SOUTHERN
2/3 OF ND INTO NRN MN WITH QPF INDICATING UP TO 4 INCHES OF SNOW
PSBL. 12Z GFS A BIT FARTHER SOUTH BUT QUITE A BIT WEAKER ALONG
ND/SD BORDER WHILE 12Z GEM IS SIMILAR IN STRENGTH TO ECMWF BUT MORE
SO ALONG ND/SD BORDER INTO THE DULUTH AREA. SFC LOW WITH THIS
SYSTEM WAY SOUTH BUT A GOOD MID LEVEL FRONTOGENETIC ZONE IS PRESENT
IN THE COLD AIR. KEPT ALL BLEND POPS WHICH IS 20S TO AROUND 50 PCT
NORTH TO SOUTH. AFTERWARDS COLDER AIR TO MOVE IN...THOUGH ALL
MODELS NOT QUITE AS COLD FRI-SAT WITH EURO WITH THE BIGGER DUMP OF
COLD AIR SUNDAY WHEREAS GFS IS A BIT WARMER. KEPT ALL BLEND TEMPS
AGAIN FOR NOW BUT AS WE SAW MONDAY MORNING LOW TEMPS STRONGLY
DEPENDENT ON WIND AND CLOUD COVER.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 646 PM CST SUN DEC 15 2013
MOSTLY VFR CIGS EXPECTED THROUGH THE OVERNIGHT. HOWEVER...THERE IS
A DECENT CHANCE FOR BRIEF PERIODS OF MVFR CONDITIONS IN LOWER CIGS
AND/OR SNOWFALL. SOUTHEAST WINDS WILL INCREASE TO 10 TO 20
KNOTS...THEN TURN WESTERLY ON MONDAY WITH HIGHER GUSTS TO 25
KNOTS. SKIES ARE EXPECTED TO CLEAR AS THE WINDS BECOME WESTERLY ON
MONDAY.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...TG
SHORT TERM...GODON
LONG TERM...GODON/RIDDLE
AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1145 PM CST FRI DEC 13 2013
.UPDATE...
ISSUED AT 1144 PM CST FRI DEC 13 2013
SNOW HAS BRIEFLY ENDED IN THE NORTHWESTERN CWA SO CUT BACK POPS
DURING THE NEXT FEW HOURS. HOWEVER...MORE IS UPSTREAM AS SEEN ON
CANADIAN RADAR. NAM AND RAP SEEM TO HAVE A FAIRLY GOOD HANDLE ON
SNOW...SO WENT JUST FOR A BREAK IN THE NORTH DURING THE NEXT FEW
HOURS AND THEN HIGH POPS AGAIN AFTER 06Z TONIGHT. TEMPS CONTINUE
TO BE ON TRACK.
UPDATE ISSUED AT 927 PM CST FRI DEC 13 2013
MAIN ISSUE FOR THE UPDATE IS TEMPS AND THE WIND CHILLS. TEMPS SEEM
ON TRACK TO DROP INTO THE TEENS BELOW ZERO IN THE NORTH TO NEAR
ZERO IN THE SOUTH. WINDS WILL CONTINUE TO DIMINISH...AND MOST
LOCATIONS ARE ALREADY BELOW WIND CHILL CRITERIA. THE EXCEPTION IS
IN THE DEVILS LAKE AREA...BUT WITH WINDS CONTINUING TO GO DOWN
THINK THIS WILL NOT LAST MUCH LONGER THAN AN HOUR OR TWO. LET THE
WIND CHILL ADVISORY EXPIRE ON TIME AT 9 PM. HIGH POP/LOW QPF SNOW
LOOKS LIKE IT WILL CONTINUE...SO MADE ONLY MINOR TWEAKS TO POPS.
UPDATE ISSUED AT 629 PM CST FRI DEC 13 2013
MADE ONLY A FEW MINOR TWEAKS TO POPS AS VERY LIGHT SNOW CONTINUES
TO BE REPORTED IN PORTIONS OF THE WESTERN AND SOUTHERN CWA. THINK
THAT THE HIGH POP/LOW QPF SITUATION CONTINUES TO SEEM VALID. TEMPS
WILL CONTINUE TO DROP INTO THE TEENS BELOW ZERO...AND WE SHOULD
SEE WINDS FALL OFF LATER TONIGHT AND THE WIND CHILL THREAT
DIMINISH.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 316 PM CST FRI DEC 13 2013
THE BAND OF SNOW WHICH PRODUCED AN INCH OR TWO OF FRESH SNOW LAST
NIGHT INTO THIS MORNING ROUGHLY FROM SOUTHEASTERN SASK THROUGH
DEVILS LAKE REGION TO THE MID RED RIVER VALLEY IS WEAKENING THOUGH
SOME LIGHT SNOW WILL CONTINUE IN THE FAR WEST AND SOUTHWESTERN
FCST AREA THIS EVE. NEXT SHORT WAVE SEEN OVER EAST CENTRAL ALBERTA
ON WATER VAPOR IS PRODUCING SNOW IN CENTRAL SASK WHERE 10-15 CM
ARE EXPECTED. THIS AREA OF SNOW WILL DROP SOUTHEAST INTO NE ND/FAR
NW MN NR 06Z AND SPREAD EAST-SOUTHEAST INTO SATURDAY MORNING. THE
LIGHT SNOW WILL END IN ERN ND SAT MORNING AND NW MN SAT AFTN.
COORD WITH NEIGHBORS AND ALL AGREED WITH THE HIGH POP/LOW QPF
ANGLE SO HAVE HIGH POPS TONIGHT INTO SATURDAY MORNING. SIMILAR
AMOUNTS TO THIS PAST WAVE WITH MOST AREAS AN INCH OR LESS WITH
POCKETS OF 2 INCHES..ESP IT SEEMS VIA HPC QPF IN NORTHEASTERN ND.
THE BEST LOW LEVEL COLD ADVECTION DOES END THIS EVENING AND AS
WAVE COMES DOWN OVERALL DONT EXPECT A BIG FALL TONIGHT TEMP WISE.
WINDS WILL LIGHTEN OVERNIGHT AS PUSH OF COLD AIR EASES AND WINDS
4 KTS OR LESS AND NOT ENOUGH TO PUSH WIND CHILL VALUES INTO THE
ADVISORY RANGE PAST ABOUT 05Z. THUS WILL LET CURRENT WIND CHILL
ADV EXPIRE ON TIME AT 03Z. COULD BE A 1-3 HOUR PERIOD WITH A FEW
SITES IN ADVISORY RANGE ON THE LOW END BUT NOT NOTEWORTHY.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 316 PM CST FRI DEC 13 2013
NEXT 500 MB SHORT WAVE SEEN WEST OF JUNEAU ALASKA WILL MOVE
SOUTHEAST SUNDAY INTO MONDAY. THIS WILL MAINLY GO A BIT
NORTH...BUT WARM ADVECTION PRETTY STRONG AND EXPECT A BAND OF
LIGHT SNOW TO AGAIN SPREAD OVER THE AREA LATE SAT NIGHT IN THE FAR
WEST AND SUNDAY ELSEWHERE WITH UP TO 1 INCH OF NEW SNOWFALL. VERY
TIGHT TEMP GRADIENT EXPECTED WITH A BREEZY SOUTH WIND LIKELY TO
DEVELOP SAT NIGHT AND CONTINUE INTO SUNDAY EAST OF SURFACE
TROUGH/WARM FRONT WHICH 12Z SUN WILL BE IN CNTRL ND. QUITE COLD
STILL EAST OF FRONT....BUT AS OFTEN THE CASE LOOK FOR TEMP RISE TO
COINCIDE WITH PASSAGE OF TROUGH/WARM FRONT SUN MIDDAY-AFTN AND A
WIND SHIFT TO THE WEST. 850 MB TEMPS WARMEST 12Z-18Z SUN THEN
COOL...BUT COLD AIR ADVECTION AT SURFACE LAGS ABOUT 6 HOURS...SO
DO EXPECT MILD TEMPS INTO SUN EVE IN THE SOUTH BEFORE COLD AIR
DROPS BACK SOUTH. KEPT IDEA OF MID TO UPPER 20S EAST OF THE RED
RIVER VALLEY AND AROUND 30 IN THE RED RIVER VALLEY AND LOWER 30S
OR PSBLY MID 30S HIGHER TERRAIN WEST OF THE RED RIVER VALLEY...ESP
AREAS CLOSER TO THE SOUTH DAKOTA BORDER.
PRECIPITATION CHANCES FOR THE FIRST HALF OF THE WEEK ARE ESSENTIALLY
NIL AS THE TRAIN OF WEAK DISTURBANCES CONTINUES TO MOVE THROUGH
NORTHWEST FLOW ALOFT. A FORECAST OF SNOW FORECAST BECOMES
MORE TO RECKON WITH LATE WEDNESDAY INTO THURSDAY AS MODELS SHOW A
LARGE TROUGH DIGGING INTO THE GREAT BASIN AND DESERT SOUTHWEST.
MORE TO THE DETAILS...GFS IS PORTRAYING NORTHWEST FLOW REGIME WITH
A DEFINED HYBRID TYPE CYCLONIC SYSTEM MOVING INTO UPPER MIDWEST
DURING THURSDAY. INVERTED TROUGH SEEMS TO BE FOCUSED OVER
NORTHEAST CWA WHERE MOST ACTIVE WEATHER WOULD BE LIKELY. AFTER THAT
JUST MORE ARCTIC COLD FOR FRIDAY AS H1000-500 THICKNESSES DROP BELOW
500 HPA ONCE MORE. ECMWF IN AGREEMENT WITH RESPECT TO A SYSTEM FOR
THURSDAY BUT IT IS MORE DIFFUSE IN NATURE. POPS ARE HIGHEST DURING
THIS PERIOD...IN THE CHC CATEGORY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1144 PM CST FRI DEC 13 2013
VFR CIGS WILL CONTINUE...ALTHOUGH A SNOW BAND OVER KFAR HAS KEPT
VIS BOUNCING BETWEEN 1 AND 2SM. THAT BAND WILL MOVE SOUTH...BUT
ANOTHER ROUND OF LIGHT SNOW WILL MOVE IN FROM THE NORTHWEST. THINK
THAT VIS WILL BE AROUND 3 TO 5SM WITH CIGS IN THE MVFR CATEGORY.
THE LIGHT SNOW AND LOWER CIGS WILL LINGER INTO THE MORNING HOURS
BEFORE MOVING OFF TO THE EAST. VFR CONDITIONS SHOULD RETURN BY
AFTERNOON. WINDS WILL BE LIGHT AND VARIABLE BEFORE PICKING UP A
BIT OUT OF THE NORTHWEST BY THE END OF THE PERIOD.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...JR
SHORT TERM...RIDDLE
LONG TERM...WJB/RIDDLE
AVIATION...JR
AREA FORECAST DISCUSSION
NWS NORMAN OK
1100 AM CST SAT DEC 14 2013
.AVIATION...
MFVR CEILINGS WILL SHIFT EAST OF TAF SITES SHORTLY AFTER BEGINNING
OF FORECAST PERIOD WITH VFR CONDITIONS THROUGH REMAINDER OF FORECAST.
GUSTY NORTH WINDS WILL ALSO BEGIN TO DECREASE THIS AFTN AND BECOME
LIGHT AROUND SUNSET. LIGHT WINDS WILL CONTINUE OVERNIGHT WITH A
GRADUAL SHIFT TO THE WEST AND SOUTHWEST. AN INCREASE IN MID/HIGH
CLOUDS EXPECTED AFTER 14Z SUNDAY.
30
&&
.PREV DISCUSSION... /ISSUED 515 AM CST SAT DEC 14 2013/
.DISCUSSION...
AVIATION DISCUSSION FOR THE 12Z TAFS IS BELOW.
&&
.AVIATION...
IMPROVING CONDITIONS ARE EXPECTED.
MAINLY MVFR CONDITIONS WITH PATCHES OF IFR CONDITIONS WILL CONTINUE
AT ALL SITES THROUGH AT LEAST 15Z. CONDITIONS WILL IMPROVE WEST TO
EAST 15-20Z. HAVE HIGH CONFIDENCE THAT ALL SITES WILL BE VFR BY 20Z.
GUSTY NORTH TO NORTHWEST WINDS CAN BE EXPECTED AT ALL SITES...
SLOWLY DIMINISHING AFTER 20Z...THEN WEAKENING SIGNIFICANTLY 22-24Z.
MBS
&&
.PREV DISCUSSION... /ISSUED 338 AM CST SAT DEC 14 2013/
DISCUSSION...
WARMER WEATHER OVER THE NEXT SEVERAL DAYS WILL BE THE MAIN WEATHER
STORY.
DENSE FOG ADVISORY ACROSS MAINLY SOUTHERN OKLAHOMA IS IN OKAY
SHAPE...THOUGH VISIBILITIES HAVE BEEN INCREASING RAPIDLY DUE TO
INCREASING LOW LEVEL WINDS AND COLD AIR ADVECTION BEHIND A COLD
FRONT THAT WAS NEAR A WAURIKA TO SEMINOLE LINE AT 330 AM. THE
ADVISORY GOES UNTIL 6 AM THIS MORNING AND MAY BE CANCELLED BEFORE
THEN AS VISIBILITIES SHOULD CONTINUE TO IMPROVE.
KEPT PATCHY DRIZZLE/PATCHY FREEZING DRIZZLE THIS MORNING EAST OF
I-35 AS LATEST RADARS INDICATED LIGHT ECHOES EAST OF WICHITA AND
NEAR TULSA. LATEST HRRR RUNS AND THE RADAR DATA SHOW THAT SOME OF
THIS VERY LIGHT PRECIPITATION MAY AFFECT LOCATIONS EAST OF I-35.
NO PROBLEMS ARE EXPECTED AS THE PRECIPITATION WOULD BE VERY LIGHT
AND MOST LIKELY EVAPORATE ON SURFACES DUE TO THE BRISK NORTH
WINDS.
TODAY WILL BE A BRISK AND COLDER DAY. CLOUDS WILL ERODE WEST TO
EAST WITH THE CLEARING LINE NEAR I-35 AROUND NOON. MODEL GUIDANCE
HIGHS IN THE MID 30S EAST OF I-35 TO THE UPPER 40S ACROSS FAR
WESTERN NORTH TEXAS WERE ACCEPTED.
TONIGHT...CLEAR AND SEASONABLY COLD CONDITIONS WILL OCCUR WITH
LOWS MAINLY IN THE 20S.
SUNDAY WILL BE SUNNY AND WARMER. THINK HIGHS WILL GET IN THE 50S
AREAWIDE...AND PERHAPS ABOVE 60 DEGREES ACROSS PARTS OF WESTERN
OKLAHOMA AND WESTERN NORTH TEXAS.
SUNDAY NIGHT THROUGH THURSDAY...A PERIOD OF WARM AND DRY CAN BE
EXPECTED. TEMPERATURES WILL GENERALLY BE 5 TO 15 DEGREES ABOVE
AVERAGE. HIGHS MAY GET ABOVE 70 DEGREES IN A FEW LOCATIONS.
THURSDAY NIGHT INTO FRIDAY...CONFIDENCE IS GROWING THAT MUCH
COLDER AIR WILL RETURN TO THE AREA WITH AN ARCTIC COLD FRONT.
WINTRY PRECIPITATION MAY RESULT. PRECIPITATION TYPES...
LOCATIONS...AND AMOUNTS REMAIN VERY UNCERTAIN. FOR NOW...KEPT LOW
PRECIPITATION CHANCES ACROSS THE AREA MAINLY ON FRIDAY.
MBS
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 37 26 58 31 / 0 0 0 0
HOBART OK 43 25 56 27 / 0 0 0 0
WICHITA FALLS TX 46 26 61 30 / 0 0 0 0
GAGE OK 47 21 59 23 / 0 0 0 0
PONCA CITY OK 38 24 56 27 / 0 0 0 0
DURANT OK 40 28 53 33 / 0 0 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR OKZ043-
047-048-051-052.
TX...NONE.
&&
$$
25/17/17
AREA FORECAST DISCUSSION
NWS NORMAN OK
515 AM CST SAT DEC 14 2013
.DISCUSSION...
AVIATION DISCUSSION FOR THE 12Z TAFS IS BELOW.
&&
.AVIATION...
IMPROVING CONDITIONS ARE EXPECTED.
MAINLY MVFR CONDITIONS WITH PATCHES OF IFR CONDITIONS WILL CONTINUE
AT ALL SITES THROUGH AT LEAST 15Z. CONDITIONS WILL IMPROVE WEST TO
EAST 15-20Z. HAVE HIGH CONFIDENCE THAT ALL SITES WILL BE VFR BY 20Z.
GUSTY NORTH TO NORTHWEST WINDS CAN BE EXPECTED AT ALL SITES...
SLOWLY DIMINISHING AFTER 20Z...THEN WEAKENING SIGNIFICANTLY 22-24Z.
MBS
&&
.PREV DISCUSSION... /ISSUED 338 AM CST SAT DEC 14 2013/
DISCUSSION...
WARMER WEATHER OVER THE NEXT SEVERAL DAYS WILL BE THE MAIN WEATHER
STORY.
DENSE FOG ADVISORY ACROSS MAINLY SOUTHERN OKLAHOMA IS IN OKAY
SHAPE...THOUGH VISIBILITIES HAVE BEEN INCREASING RAPIDLY DUE TO
INCREASING LOW LEVEL WINDS AND COLD AIR ADVECTION BEHIND A COLD
FRONT THAT WAS NEAR A WAURIKA TO SEMINOLE LINE AT 330 AM. THE
ADVISORY GOES UNTIL 6 AM THIS MORNING AND MAY BE CANCELLED BEFORE
THEN AS VISIBILITIES SHOULD CONTINUE TO IMPROVE.
KEPT PATCHY DRIZZLE/PATCHY FREEZING DRIZZLE THIS MORNING EAST OF
I-35 AS LATEST RADARS INDICATED LIGHT ECHOES EAST OF WICHITA AND
NEAR TULSA. LATEST HRRR RUNS AND THE RADAR DATA SHOW THAT SOME OF
THIS VERY LIGHT PRECIPITATION MAY AFFECT LOCATIONS EAST OF I-35.
NO PROBLEMS ARE EXPECTED AS THE PRECIPITATION WOULD BE VERY LIGHT
AND MOST LIKELY EVAPORATE ON SURFACES DUE TO THE BRISK NORTH
WINDS.
TODAY WILL BE A BRISK AND COLDER DAY. CLOUDS WILL ERODE WEST TO
EAST WITH THE CLEARING LINE NEAR I-35 AROUND NOON. MODEL GUIDANCE
HIGHS IN THE MID 30S EAST OF I-35 TO THE UPPER 40S ACROSS FAR
WESTERN NORTH TEXAS WERE ACCEPTED.
TONIGHT...CLEAR AND SEASONABLY COLD CONDITIONS WILL OCCUR WITH
LOWS MAINLY IN THE 20S.
SUNDAY WILL BE SUNNY AND WARMER. THINK HIGHS WILL GET IN THE 50S
AREAWIDE...AND PERHAPS ABOVE 60 DEGREES ACROSS PARTS OF WESTERN
OKLAHOMA AND WESTERN NORTH TEXAS.
SUNDAY NIGHT THROUGH THURSDAY...A PERIOD OF WARM AND DRY CAN BE
EXPECTED. TEMPERATURES WILL GENERALLY BE 5 TO 15 DEGREES ABOVE
AVERAGE. HIGHS MAY GET ABOVE 70 DEGREES IN A FEW LOCATIONS.
THURSDAY NIGHT INTO FRIDAY...CONFIDENCE IS GROWING THAT MUCH
COLDER AIR WILL RETURN TO THE AREA WITH AN ARCTIC COLD FRONT.
WINTRY PRECIPITATION MAY RESULT. PRECIPITATION TYPES...
LOCATIONS...AND AMOUNTS REMAIN VERY UNCERTAIN. FOR NOW...KEPT LOW
PRECIPITATION CHANCES ACROSS THE AREA MAINLY ON FRIDAY.
MBS
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 37 26 58 31 / 0 0 0 0
HOBART OK 43 25 56 27 / 0 0 0 0
WICHITA FALLS TX 46 26 61 30 / 0 0 0 0
GAGE OK 47 21 59 23 / 0 0 0 0
PONCA CITY OK 38 24 56 27 / 0 0 0 0
DURANT OK 40 28 53 33 / 0 0 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR OKZ043-
047-048-051-052.
TX...NONE.
&&
$$
25/17/17
AREA FORECAST DISCUSSION
NWS NORMAN OK
338 AM CST SAT DEC 14 2013
.DISCUSSION...
WARMER WEATHER OVER THE NEXT SEVERAL DAYS WILL BE THE MAIN WEATHER
STORY.
DENSE FOG ADVISORY ACROSS MAINLY SOUTHERN OKLAHOMA IS IN OKAY
SHAPE...THOUGH VISIBILITIES HAVE BEEN INCREASING RAPIDLY DUE TO
INCREASING LOW LEVEL WINDS AND COLD AIR ADVECTION BEHIND A COLD
FRONT THAT WAS NEAR A WAURIKA TO SEMINOLE LINE AT 330 AM. THE
ADVISORY GOES UNTIL 6 AM THIS MORNING AND MAY BE CANCELLED BEFORE
THEN AS VISIBILITIES SHOULD CONTINUE TO IMPROVE.
KEPT PATCHY DRIZZLE/PATCHY FREEZING DRIZZLE THIS MORNING EAST OF
I-35 AS LATEST RADARS INDICATED LIGHT ECHOES EAST OF WICHITA AND
NEAR TULSA. LATEST HRRR RUNS AND THE RADAR DATA SHOW THAT SOME OF
THIS VERY LIGHT PRECIPITATION MAY AFFECT LOCATIONS EAST OF I-35.
NO PROBLEMS ARE EXPECTED AS THE PRECIPITATION WOULD BE VERY LIGHT
AND MOST LIKELY EVAPORATE ON SURFACES DUE TO THE BRISK NORTH
WINDS.
TODAY WILL BE A BRISK AND COLDER DAY. CLOUDS WILL ERODE WEST TO
EAST WITH THE CLEARING LINE NEAR I-35 AROUND NOON. MODEL GUIDANCE
HIGHS IN THE MID 30S EAST OF I-35 TO THE UPPER 40S ACROSS FAR
WESTERN NORTH TEXAS WERE ACCEPTED.
TONIGHT...CLEAR AND SEASONABLY COLD CONDITIONS WILL OCCUR WITH
LOWS MAINLY IN THE 20S.
SUNDAY WILL BE SUNNY AND WARMER. THINK HIGHS WILL GET IN THE 50S
AREAWIDE...AND PERHAPS ABOVE 60 DEGREES ACROSS PARTS OF WESTERN
OKLAHOMA AND WESTERN NORTH TEXAS.
SUNDAY NIGHT THROUGH THURSDAY...A PERIOD OF WARM AND DRY CAN BE
EXPECTED. TEMPERATURES WILL GENERALLY BE 5 TO 15 DEGREES ABOVE
AVERAGE. HIGHS MAY GET ABOVE 70 DEGREES IN A FEW LOCATIONS.
THURSDAY NIGHT INTO FRIDAY...CONFIDENCE IS GROWING THAT MUCH
COLDER AIR WILL RETURN TO THE AREA WITH AN ARCTIC COLD FRONT.
WINTRY PRECIPITATION MAY RESULT. PRECIPITATION TYPES...
LOCATIONS...AND AMOUNTS REMAIN VERY UNCERTAIN. FOR NOW...KEPT LOW
PRECIPITATION CHANCES ACROSS THE AREA MAINLY ON FRIDAY.
MBS
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 37 26 58 31 / 0 0 0 0
HOBART OK 43 25 56 27 / 0 0 0 0
WICHITA FALLS TX 46 26 61 30 / 0 0 0 0
GAGE OK 47 21 59 23 / 0 0 0 0
PONCA CITY OK 38 24 56 27 / 0 0 0 0
DURANT OK 40 28 53 33 / 0 0 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
OKZ028>032-039>043-045>048-050>052.
TX...DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR TXZ090.
&&
$$
25/17
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1015 PM EST SUN DEC 15 2013
.SYNOPSIS...
A DISTURBANCE ALOFT WILL MOVE SOUTHEAST ACROSS THE GREAT LAKES
TONIGHT INTO MONDAY REINFORCING THE COLD AIR. ANOTHER CLIPPER TYPE
DISTURBANCE WILL TRACK ACROSS THE AREA LATE MONDAY NIGHT AND
TUESDAY. MILDER AIR WILL BRIEFLY RETURN THURSDAY AND FRIDAY
BEFORE A FRONT DELIVERS MORE COLD AIR FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A SERIES OF SHORTWAVES EMBEDDED IN THE NW FLOW ALOFT WILL
CONTINUE TO DIVE SE OUT OF THE CENTRAL GR LAKES. THE CONTINUED
COLD FLOW OVER THE GR LAKES WILL HELP MAINTAIN PLENTIFUL CLOUD
COVER OVER MOST OF CENTRAL AND WESTERN PA ALONG WITH FRQT SNOW
SHOWERS IN THE USUAL AREAS DOWNWIND OF LAKE ERIE AND IN THE LAUREL
HIGHLANDS. A PRETTY TYPICAL NW FLOW REGIME IN THE WAKE OF
SATURDAY`S WINTER STORM.
THE FAIRLY STEADY LIGHT SNOW THAT`S BEEN PREVALENT ACROSS THE NRN
AND WRN MTNS OF THE STATE SHOULD AMOUNT TO PERHAPS AN INCH OR TWO
FROM KBFD DOWN TO KJST. OCCASIONAL VERY LIGHT SNOW AND FLURRIES
WILL CONTINUE TO SPILL OVER INTO THE CENTRAL RIDGE AND VALLEY
REGION. I TRIMMED BACK POPS AND QPF IN THESE CENTRAL AREAS WHERE
MOST PLACES WILL SEE NO ACCUMULATIONS OF SNOW.
THE COLD AIR MOVING OVER THE LAKES WILL GRADUALLY TAKE ON MORE OF
A WNW TRAJECTORY ALLOWING FOR THE POSSIBILITY THAT SOME BETTER
ORGANIZED LAKE SNOW BANDS CAN WORK THEIR WAY FURTHER SOUTH INTO THE
NW MOUNTAINS THIS EVENING AND OVERNIGHT. THE HIGH RESOLUTION RAP
AND 4KM NAM/ARW EACH SHOW THIS EVOLUTION.
FROM EARLIER...
EXPANDED THE WINTER WEATHER ADVISORY TO MCKEAN COUNTY FOR
LATE THIS EVENING THROUGH 15Z MONDAY...AS THE MODERATELY STRONG
MEAN BLYR FLOW VEERS ABOUT 20-30 DEG...BACK TO A 270-280
DIRECTION. THIS TYPE OF STEADY STATE WNW FLOW TYPICALLY SUPPORTS A
LONGER DURATION/SINGLE LES BAND THAT CAN PENETRATE FAIRLY FAR
INLAND. A LIGHT COATING OF SNOW IS POSSIBLE LATER TONIGHT AND
MONDAY MORNING IN THE KIPT AREA WITH SOME PTS TO THE NORTH AND
EAST SEEING A QUICK HALF INCH TO ONE-INCH.
THE FCST SNOW AMOUNTS EMPLOY A BLEND OF HIGH RESOLUTION MODELS AND
ANTICIPATED SNOWFALL RATES AND RESIDENCE TIME OF THE SNOW-BANDS USING
MEAN SFC-875MB WIND OFF THE RAP AND NAM BUFKIT PROFILES.
MEAN SNOWFALL FOR WARREN CTY IS IN THE 3-6 INCH RANGE...WHILE 2-4
INCHES IS LIKELY ACROSS THE NW HALF OF MCKEAN COUNTY/.
THE NAM IMPLIES AN EXTENSIVE QUASI-SINGLE BAND STRUCTURE PENETRATING
FAR INLAND ACROSS THE NRN TIER COUNTIES...AND PERHAPS THROUGH
SULLIVAN CTY ON TWD THE POCONOS.
THIS SIMULATION AND THE RAP MAKE IT CLEAR BOTH FORECAST SYSTEMS
THINK THERE SHOULD BE A GOOD LES BAND IN SOUTHERN NY AND NW PA
OVERNIGHT TONIGHT.
OUTSIDE THE LES AND UPSLOPE SNOW AREAS...IT WILL BE A VERY COLD
EVENING AND OVERNIGHT WITH GUSTY WINDS...TO AROUND 30 MPH AT TIMES.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
WEAK RIDGING SLIDES OVER THE AREA BENEATH THE FAST WESTERLY FLOW
ALOFT. LAKE EFFECT SNOW SHOWERS WILL DECREASE IN INTENSITY AND
BECOME MORE MULTI-BANDED ACROSS THE NW MTNS IN THE MORNING...BEFORE
LIFTING NORTH AND DIMINISHING DURING THE AFTERNOON.
IT/LL BE QUITE COLD MONDAY WITH MAX TEMPS ONLY IN THE UPPER TEENS TO
LOWER 20S ACROSS THE MTNS...AND MID TO UPPER 20S IN THE SUSQ VALLEY.
THESE TEMPS WILL BE ABOUT 15F BELOW NORMAL.
SIGNIFICANT BREAKS IN THE STRATO CU WILL DEVELOP ACROSS THE CENTRAL
AND SE ZONES MONDAY WHILE SKY COVER STAYS BKN-OVC ACROSS THE LAURELS
AND NW MTNS DUE TO LLVL UPSLOPE FLOW AND THICKER MID/HIGH CLOUDS
SPREADING IN LATE AHEAD OF A POTENT CLIPPER.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
THE GEFS-CMCEPS-SREF ALL SHOWS A CLIPPER PASSING TO OUR NORTH
TUESDAY. TIMING VARIES AND TRACK IS TO OUR NORTH THUS ANY
PRECIPITATION SHOULD BE LIGHT. TRIED TO SHOW THE POTENTIAL FOR
LIGHT SNOW TUESDAY. KEPT SNOW GENERALLY LOWER THAN 1 INCH AND
MAINLY CENTRAL AND NORTHERN AREAS.
THE NW FLOW WEAKENS AS A 500 HPA LOW DEVELOPS IN SW US LATER IN
THE WEEK. THIS ALLOWS FOR SOUTHWESTERLY FLOW AND A GRADUAL WARM UP
LIKELY THURSDAY INTO FRIDAY. MODELS IMPLY WARMEST DAY WOULD BE
FRIDAY. THIS WILL NOT LAST AS MODELS SHOWS DEEPENING TROUGH TO OUR
NORTH AND WEST AND A POOL OF ARCTIC AIR MOVING INTO THE LAKES
FRIDAY INTO SATURDAY. THUS SURFACE COLD FRONT SHOULD PUSH COLD AIR
BACK INTO OUR REGION SOMETIME NEXT WEEKEND.
BIAS CORRECT GEFS AND NAEFS SUGGEST TROUGH AND GENERALLY COLD
WEATHER SETTLE BACK IN THIS COMING WEEKEND AND INTO THE CHRISTMAS
WEEK.
AT THIS TIME NO BIG STORMS IN THE ENSEMBLES.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
16/03Z...HIGHEST CONFIDENCE IN IFR CONDS REMAINS AT BFD WHERE LES
SHOULD BECOME MORE OF A FACTOR AS THE LLVL FLOW VEERS MORE TO THE
WNW BEHIND POTENT UPPER LEVEL DISTURBANCES CROSSING SERN CANADA. SFC
WNDS/GUSTS HAVE BEEN NOTICEABLY STRONGER THAN FCST /IN THE 20-35KT
RANGE/ AT JST AND AOO...WITH BLSN ADDED TO JST TAF PER 03Z OB.
LOWERED THE WINDS AT MDT/LNS WITH IR SATL SHOWING THE BKN STRATOCU
ON THE DOORSTEP AT LNS.
A FAST AND PERSISTENT WEST-NORTHWEST FLOW ALOFT WITH A SERIES OF
EMBEDDED CLIPPER SYSTEMS WILL RESULT IN WIDESPREAD MVFR CIGS AND
MVFR-IFR VISBYS AT BFD/JST...WITH OCNL MVFR-IFR CONDS FURTHER EAST
ACRS THE CENTRAL AND EASTERN AIRFIELDS. MUCH OF THE AIRSPACE COULD
SEE -SN AND ASSOCD MVFR TO IFR VIS MON NGT- TUE NGT. IMPROVING
CONDS SHOULD ARRIVE LATER WED INTO THUR AS HIGH PRESSURE EXPANDS
OVER THE REGION. ANOTHER FRONTAL SYSTEM SHOULD ARRIVE BY FRIDAY
WITH TEMPERATURES INITIALLY WARM ENOUGH FOR RAIN.
OUTLOOK...
MON...MAINLY VFR CENTRAL/EAST. MVFR-IFR IN SHSN AT BFD/JST.
MON NGT-TUE NGT...WIDESPREAD LGT SNOW/REDUCED VSBYS POSSIBLE.
WED-THU...SHSN/REDUCED VSBYS WEST BCMG VFR. VFR ELSEWHERE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST MONDAY FOR PAZ004-
005.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LAMBERT
LONG TERM...GRUMM/CERU
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
939 PM EST SUN DEC 15 2013
.SYNOPSIS...
A DISTURBANCE ALOFT WILL MOVE SOUTHEAST ACROSS THE GREAT LAKES
TONIGHT INTO MONDAY REINFORCING THE COLD AIR. ANOTHER CLIPPER TYPE
DISTURBANCE WILL TRACK ACROSS THE AREA LATE MONDAY NIGHT AND
TUESDAY. MILDER AIR WILL BRIEFLY RETURN THURSDAY AND FRIDAY
BEFORE A FRONT DELIVERS MORE COLD AIR FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A SERIES OF SHORTWAVES EMBEDDED IN THE NW FLOW ALOFT WILL
CONTINUE TO DIVE SE OUT OF THE CENTRAL GR LAKES. THE CONTINUED
COLD FLOW OVER THE GR LAKES WILL HELP MAINTAIN PLENTIFUL CLOUD
COVER OVER MOST OF CENTRAL AND WESTERN PA ALONG WITH FRQT SNOW
SHOWERS IN THE USUAL AREAS DOWNWIND OF LAKE ERIE AND IN THE LAUREL
HIGHLANDS. A PRETTY TYPICAL NW FLOW REGIME IN THE WAKE OF
SATURDAY`S WINTER STORM.
THE FAIRLY STEADY LIGHT SNOW THAT`S BEEN PREVALENT ACROSS THE NRN
AND WRN MTNS OF THE STATE SHOULD AMOUNT TO PERHAPS AN INCH OR TWO
FROM KBFD DOWN TO KJST. OCCASIONAL VERY LIGHT SNOW AND FLURRIES
WILL CONTINUE TO SPILL OVER INTO THE CENTRAL RIDGE AND VALLEY
REGION. I TRIMMED BACK POPS AND QPF IN THESE CENTRAL AREAS WHERE
MOST PLACES WILL SEE NO ACCUMULATIONS OF SNOW.
THE COLD AIR MOVING OVER THE LAKES WILL GRADUALLY TAKE ON MORE OF
A WNW TRAJECTORY ALLOWING FOR THE POSSIBILITY THAT SOME BETTER
ORGANIZED LAKE SNOW BANDS CAN WORK THEIR WAY FURTHER SOUTH INTO THE
NW MOUNTAINS THIS EVENING AND OVERNIGHT. THE HIGH RESOLUTION RAP
AND 4KM NAM/ARW EACH SHOW THIS EVOLUTION.
FROM EARLIER...
EXPANDED THE WINTER WEATHER ADVISORY TO MCKEAN COUNTY FOR
LATE THIS EVENING THROUGH 15Z MONDAY...AS THE MODERATELY STRONG
MEAN BLYR FLOW VEERS ABOUT 20-30 DEG...BACK TO A 270-280
DIRECTION. THIS TYPE OF STEADY STATE WNW FLOW TYPICALLY SUPPORTS A
LONGER DURATION/SINGLE LES BAND THAT CAN PENETRATE FAIRLY FAR
INLAND. A LIGHT COATING OF SNOW IS POSSIBLE LATER TONIGHT AND
MONDAY MORNING IN THE KIPT AREA WITH SOME PTS TO THE NORTH AND
EAST SEEING A QUICK HALF INCH TO ONE-INCH.
THE FCST SNOW AMOUNTS EMPLOY A BLEND OF HIGH RESOLUTION MODELS AND
ANTICIPATED SNOWFALL RATES AND RESIDENCE TIME OF THE SNOW-BANDS USING
MEAN SFC-875MB WIND OFF THE RAP AND NAM BUFKIT PROFILES.
MEAN SNOWFALL FOR WARREN CTY IS IN THE 3-6 INCH RANGE...WHILE 2-4
INCHES IS LIKELY ACROSS THE NW HALF OF MCKEAN COUNTY/.
THE NAM IMPLIES AN EXTENSIVE QUASI-SINGLE BAND STRUCTURE PENETRATING
FAR INLAND ACROSS THE NRN TIER COUNTIES...AND PERHAPS THROUGH
SULLIVAN CTY ON TWD THE POCONOS.
THIS SIMULATION AND THE RAP MAKE IT CLEAR BOTH FORECAST SYSTEMS
THINK THERE SHOULD BE A GOOD LES BAND IN SOUTHERN NY AND NW PA
OVERNIGHT TONIGHT.
OUTSIDE THE LES AND UPSLOPE SNOW AREAS...IT WILL BE A VERY COLD
EVENING AND OVERNIGHT WITH GUSTY WINDS...TO AROUND 30 MPH AT TIMES.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
WEAK RIDGING SLIDES OVER THE AREA BENEATH THE FAST WESTERLY FLOW
ALOFT. LAKE EFFECT SNOW SHOWERS WILL DECREASE IN INTENSITY AND
BECOME MORE MULTI-BANDED ACROSS THE NW MTNS IN THE MORNING...BEFORE
LIFTING NORTH AND DIMINISHING DURING THE AFTERNOON.
IT/LL BE QUITE COLD MONDAY WITH MAX TEMPS ONLY IN THE UPPER TEENS TO
LOWER 20S ACROSS THE MTNS...AND MID TO UPPER 20S IN THE SUSQ VALLEY.
THESE TEMPS WILL BE ABOUT 15F BELOW NORMAL.
SIGNIFICANT BREAKS IN THE STRATO CU WILL DEVELOP ACROSS THE CENTRAL
AND SE ZONES MONDAY WHILE SKY COVER STAYS BKN-OVC ACROSS THE LAURELS
AND NW MTNS DUE TO LLVL UPSLOPE FLOW AND THICKER MID/HIGH CLOUDS
SPREADING IN LATE AHEAD OF A POTENT CLIPPER.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
THE GEFS-CMCEPS-SREF ALL SHOWS A CLIPPER PASSING TO OUR NORTH
TUESDAY. TIMING VARIES AND TRACK IS TO OUR NORTH THUS ANY
PRECIPITATION SHOULD BE LIGHT. TRIED TO SHOW THE POTENTIAL FOR
LIGHT SNOW TUESDAY. KEPT SNOW GENERALLY LOWER THAN 1 INCH AND
MAINLY CENTRAL AND NORTHERN AREAS.
THE NW FLOW WEAKENS AS A 500 HPA LOW DEVELOPS IN SW US LATER IN
THE WEEK. THIS ALLOWS FOR SOUTHWESTERLY FLOW AND A GRADUAL WARM UP
LIKELY THURSDAY INTO FRIDAY. MODELS IMPLY WARMEST DAY WOULD BE
FRIDAY. THIS WILL NOT LAST AS MODELS SHOWS DEEPENING TROUGH TO OUR
NORTH AND WEST AND A POOL OF ARCTIC AIR MOVING INTO THE LAKES
FRIDAY INTO SATURDAY. THUS SURFACE COLD FRONT SHOULD PUSH COLD AIR
BACK INTO OUR REGION SOMETIME NEXT WEEKEND.
BIAS CORRECT GEFS AND NAEFS SUGGEST TROUGH AND GENERALLY COLD
WEATHER SETTLE BACK IN THIS COMING WEEKEND AND INTO THE CHRISTMAS
WEEK.
AT THIS TIME NO BIG STORMS IN THE ENSEMBLES.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
16/00Z...MADE NO SIGNIFICANT CHANGES TO 15/21Z UPDATED TAFS. HIRES
MDLS SHOW THE LES BAND CURRENTLY MOVG ACRS LAKE ERIE WILL IMPACT
BFD LATER TONIGHT AND COULD DROP THE VIS BLW 1SM AT TIMES LATER
TONIGHT. MOIST UPSLOPE WLY FLOW ASCENDING THE SW MTNS/JST WILL
KEEP AT LEAST BORDERLINE IFR CONDS THERE...IF NOT IFR ALTHOUGH
CONFIDENCE IS AVG.
A FAST AND PERSISTENT WEST-NORTHWEST FLOW ALOFT WITH A
SERIES OF EMBEDDED CLIPPER SYSTEMS WILL RESULT IN WIDESPREAD MVFR
CIGS AND MVFR-IFR VISBYS AT BFD/JST...WITH OCNL MVFR-IFR CONDS
FURTHER EAST ACRS THE CENTRAL AND EASTERN AIRFIELDS. MUCH OF THE
AIRSPACE COULD SEE -SN AND ASSOCD MVFR TO IFR VIS MON NGT- TUE
NGT. IMPROVING CONDS SHOULD ARRIVE LATER WED INTO THUR AS HIGH
PRESSURE EXPANDS OVER THE REGION. ANOTHER FRONTAL SYSTEM SHOULD
ARRIVE BY FRIDAY WITH TEMPERATURES INITIALLY WARM ENOUGH FOR RAIN.
OUTLOOK...
MON...MAINLY VFR CENTRAL/EAST. MVFR-IFR IN SHSN AT BFD/JST.
MON NGT-TUE NGT...WIDESPREAD LGT SNOW/REDUCED VSBYS POSSIBLE.
WED-THU...SHSN/REDUCED VSBYS WEST BCMG VFR. VFR ELSEWHERE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST MONDAY FOR PAZ004-
005.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LAMBERT
LONG TERM...GRUMM/CERU
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
731 PM EST SUN DEC 15 2013
.SYNOPSIS...
A DISTURBANCE ALOFT WILL MOVE SOUTHEAST ACROSS THE GREAT LAKES
TONIGHT INTO MONDAY REINFORCING THE COLD AIR. ANOTHER CLIPPER TYPE
DISTURBANCE WILL TRACK ACROSS THE AREA LATE MONDAY NIGHT AND
TUESDAY. MILDER AIR WILL BRIEFLY RETURN THURSDAY AND FRIDAY
BEFORE A FRONT DELIVERS MORE COLD AIR FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A WELL-DEFINED UPPER LEVEL SHORTWAVE WILL CONTINUE TO DIVE SE OUT
OF THE CENTRAL GR LAKES. THE CONTINUED COLD FLOW OVER THE GR LAKES
WILL HELP MAINTAIN PLENTIFUL CLOUD COVER OVER MOST OF CENTRAL AND
WESTERN PA ALONG WITH FRQT SNOW SHOWERS IN THE USUAL AREAS
DOWNWIND OF LAKE ERIE AND IN THE LAUREL HIGHLANDS. A PRETTY
TYPICAL NW FLOW REGIME IN THE WAKE OF SATURDAY`S WINTER STORM.
THE FAIRLY STEADY LIGHT SNOW THAT`S BEEN PREVALENT TODAY ACROSS
THE NRN AND WRN MTNS OF THE STATE SHOULD AMOUNT TO PERHAPS AN INCH
OR TWO FROM KBFD DOWN TO KJST. OCCASIONAL VERY LIGHT SNOW AND
FLURRIES WILL CONTINUE TO SPILL OVER INTO THE CENTRAL RIDGE AND
VALLEY REGION. I TRIMMED BACK POPS AND QPF IN THESE CENTRAL AREAS
WHERE MOST PLACES WILL SEE NO ACCUMULATIONS OF SNOW.
THE COLD AIR MOVING OVER THE LAKES WILL GRADUALLY TAKE ON MORE OF
A WNW TRAJECTORY ALLOWING FOR THE POSSIBILITY THAT SOME BETTER
ORGANIZED LAKE SNOW BANDS CAN WORK THEIR WAY FURTHER SOUTH INTO THE
NW MOUNTAINS THIS EVENING AND OVERNIGHT. THE HIGH RESOLUTION RAP
AND 4KM NAM/ARW EACH SHOW THIS EVOLUTION.
FROM EARLIER...
EXPANDED THE WINTER WEATHER ADVISORY TO MCKEAN COUNTY FOR
LATE THIS EVENING THROUGH 15Z MONDAY...AS THE MODERATELY STRONG
MEAN BLYR FLOW VEERS ABOUT 20-30 DEG...BACK TO A 270-280
DIRECTION. THIS TYPE OF STEADY STATE WNW FLOW TYPICALLY SUPPORTS A
LONGER DURATION/SINGLE LES BAND THAT CAN PENETRATE FAIRLY FAR
INLAND. A LIGHT COATING OF SNOW IS POSSIBLE LATER TONIGHT AND
MONDAY MORNING IN THE KIPT AREA WITH SOME PTS TO THE NORTH AND
EAST SEEING A QUICK HALF INCH TO ONE-INCH.
THE FCST SNOW AMOUNTS EMPLOY A BLEND OF HIGH RESOLUTION MODELS AND
ANTICIPATED SNOWFALL RATES AND RESIDENCE TIME OF THE SNOW-BANDS USING
MEAN SFC-875MB WIND OFF THE RAP AND NAM BUFKIT PROFILES.
MEAN SNOWFALL FOR WARREN CTY IS IN THE 3-6 INCH RANGE...WHILE 2-4
INCHES IS LIKELY ACROSS THE NW HALF OF MCKEAN COUNTY/.
THE NAM IMPLIES AN EXTENSIVE QUASI-SINGLE BAND STRUCTURE PENETRATING
FAR INLAND ACROSS THE NRN TIER COUNTIES...AND PERHAPS THROUGH
SULLIVAN CTY ON TWD THE POCONOS.
THIS SIMULATION AND THE RAP MAKE IT CLEAR BOTH FORECAST SYSTEMS
THINK THERE SHOULD BE A GOOD LES BAND IN SOUTHERN NY AND NW PA
OVERNIGHT TONIGHT.
OUTSIDE THE LES AND UPSLOPE SNOW AREAS...IT WILL BE A VERY COLD
EVENING AND OVERNIGHT WITH GUSTY WINDS...TO AROUND 30 MPH AT TIMES.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
WEAK RIDGING SLIDES OVER THE AREA BENEATH THE FAST WESTERLY FLOW
ALOFT. LAKE EFFECT SNOW SHOWERS WILL DECREASE IN INTENSITY AND
BECOME MORE MULTI-BANDED ACROSS THE NW MTNS IN THE MORNING...BEFORE
LIFTING NORTH AND DIMINISHING DURING THE AFTERNOON.
IT/LL BE QUITE COLD MONDAY WITH MAX TEMPS ONLY IN THE UPPER TEENS TO
LOWER 20S ACROSS THE MTNS...AND MID TO UPPER 20S IN THE SUSQ VALLEY.
THESE TEMPS WILL BE ABOUT 15F BELOW NORMAL.
SIGNIFICANT BREAKS IN THE STRATO CU WILL DEVELOP ACROSS THE CENTRAL
AND SE ZONES MONDAY WHILE SKY COVER STAYS BKN-OVC ACROSS THE LAURELS
AND NW MTNS DUE TO LLVL UPSLOPE FLOW AND THICKER MID/HIGH CLOUDS
SPREADING IN LATE AHEAD OF A POTENT CLIPPER.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
THE GEFS-CMCEPS-SREF ALL SHOWS A CLIPPER PASSING TO OUR NORTH
TUESDAY. TIMING VARIES AND TRACK IS TO OUR NORTH THUS ANY
PRECIPITATION SHOULD BE LIGHT. TRIED TO SHOW THE POTENTIAL FOR
LIGHT SNOW TUESDAY. KEPT SNOW GENERALLY LOWER THAN 1 INCH AND
MAINLY CENTRAL AND NORTHERN AREAS.
THE NW FLOW WEAKENS AS A 500 HPA LOW DEVELOPS IN SW US LATER IN
THE WEEK. THIS ALLOWS FOR SOUTHWESTERLY FLOW AND A GRADUAL WARM UP
LIKELY THURSDAY INTO FRIDAY. MODELS IMPLY WARMEST DAY WOULD BE
FRIDAY. THIS WILL NOT LAST AS MODELS SHOWS DEEPENING TROUGH TO OUR
NORTH AND WEST AND A POOL OF ARCTIC AIR MOVING INTO THE LAKES
FRIDAY INTO SATURDAY. THUS SURFACE COLD FRONT SHOULD PUSH COLD AIR
BACK INTO OUR REGION SOMETIME NEXT WEEKEND.
BIAS CORRECT GEFS AND NAEFS SUGGEST TROUGH AND GENERALLY COLD
WEATHER SETTLE BACK IN THIS COMING WEEKEND AND INTO THE CHRISTMAS
WEEK.
AT THIS TIME NO BIG STORMS IN THE ENSEMBLES.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
16/00Z...MADE NO SIGNIFICANT CHANGES TO 15/21Z UPDATED TAFS. HIRES
MDLS SHOW THE LES BAND CURRENTLY MOVG ACRS LAKE ERIE WILL IMPACT
BFD LATER TONIGHT AND COULD DROP THE VIS BLW 1SM AT TIMES LATER
TONIGHT. MOIST UPSLOPE WLY FLOW ASCENDING THE SW MTNS/JST WILL
KEEP AT LEAST BORDERLINE IFR CONDS THERE...IF NOT IFR ALTHOUGH
CONFIDENCE IS AVG.
A FAST AND PERSISTENT WEST-NORTHWEST FLOW ALOFT WITH A
SERIES OF EMBEDDED CLIPPER SYSTEMS WILL RESULT IN WIDESPREAD MVFR
CIGS AND MVFR-IFR VISBYS AT BFD/JST...WITH OCNL MVFR-IFR CONDS
FURTHER EAST ACRS THE CENTRAL AND EASTERN AIRFIELDS. MUCH OF THE
AIRSPACE COULD SEE -SN AND ASSOCD MVFR TO IFR VIS MON NGT- TUE
NGT. IMPROVING CONDS SHOULD ARRIVE LATER WED INTO THUR AS HIGH
PRESSURE EXPANDS OVER THE REGION. ANOTHER FRONTAL SYSTEM SHOULD
ARRIVE BY FRIDAY WITH TEMPERATURES INITIALLY WARM ENOUGH FOR RAIN.
OUTLOOK...
MON...MAINLY VFR CENTRAL/EAST. MVFR-IFR IN SHSN AT BFD/JST.
MON NGT-TUE NGT...WIDESPREAD LGT SNOW/REDUCED VSBYS POSSIBLE.
WED-THU...SHSN/REDUCED VSBYS WEST BCMG VFR. VFR ELSEWHERE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST MONDAY FOR PAZ005.
LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST MONDAY FOR PAZ004.
&&
$$
SYNOPSIS...LA CORTE/LAMBERT
NEAR TERM...LA CORTE/LAMBERT
SHORT TERM...LAMBERT
LONG TERM...GRUMM/CERU
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
651 PM EST SUN DEC 15 2013
.SYNOPSIS...
A DISTURBANCE ALOFT WILL MOVE SOUTHEAST ACROSS THE GREAT LAKES
TONIGHT INTO MONDAY REINFORCING THE COLD AIR. ANOTHER CLIPPER TYPE
DISTURBANCE WILL TRACK ACROSS THE AREA LATE MONDAY NIGHT AND
TUESDAY. MILDER AIR WILL BRIEFLY RETURN THURSDAY AND FRIDAY
BEFORE A FRONT DELIVERS MORE COLD AIR FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A WELL-DEFINED UPPER LEVEL SHORTWAVE WILL CONTINUE TO DIVE SE OUT
OF THE CENTRAL GR LAKES. THE CONTINUED COLD FLOW OVER THE GR LAKES
WILL HELP MAINTAIN PLENTIFUL CLOUDCOVER OVER MOST OF CENTRAL AND
WESTERN PA ALONG WITH FRQT SNOW SHOWERS IN THE USUAL AREAS
DOWNWIND OF LAKE ERIE AND IN THE LAUREL HIGHLANDS. A PRETTY
TYPICAL NW FLOW REGIME IN THE WAKE OF SATURDAY`S WINTER STORM.
THE FAIRLY STEADY LIGHT SNOW THAT`S BEEN PREVALENT TODAY ACROSS
THE NRN AND WRN MTNS OF THE STATE SHOULD AMOUNT TO PERHAPS AN INCH
OR TWO FROM KBFD DOWN TO KJST. OCCASIONAL VERY LIGHT SNOW AND
FLURRIES WILL CONTINUE TO SPILL OVER INTO THE CENTRAL RIDGE AND
VALLEY REGION. I TRIMMED BACK POPS AND QPF IN THESE CENTRAL AREAS
WHERE MOST PLACES WILL SEE NO ACCUMULATIONS OF SNOW.
THE COLD AIR MOVING OVER THE LAKES WILL GRADUALLY TAKE ON MORE OF
A WNW TRAJECTORY ALLOWING FOR THE POSSIBILITY THAT SOME BETTER
ORGANIZED LAKE SNOW BANDS CAN WORK THEIR WAY FURTHER SOUTH INTO THE
NW MOUNTAINS THIS EVENING AND OVERNIGHT. THE HIGH RESOLUTION RAP
AND 4KM NAM/ARW EACH SHOW THIS EVOLUTION.
FROM EARLIER...
EXPANDED THE WINTER WEATHER ADVISORY TO MCKEAN COUNTY FOR
LATE THIS EVENING THROUGH 15Z MONDAY...AS THE MODERATELY STRONG
MEAN BLYR FLOW VEERS ABOUT 20-30 DEG...BACK TO A 270-280
DIRECTION. THIS TYPE OF STEADY STATE WNW FLOW TYPICALLY SUPPORTS A
LONGER DURATION/SINGLE LES BAND THAT CAN PENETRATE FAIRLY FAR
INLAND. A LIGHT COATING OF SNOW IS POSSIBLE LATER TONIGHT AND
MONDAY MORNING IN THE KIPT AREA WITH SOME PTS TO THE NORTH AND
EAST SEEING A QUICK HALF INCH TO ONE-INCH.
THE FCST SNOW AMOUNTS EMPLOY A BLEND OF HIGH RESOLUTION MODELS AND
ANTICIPATED SNOWFALL RATES AND RESIDENCE TIME OF THE SNOW-BANDS USING
MEAN SFC-875MB WIND OFF THE RAP AND NAM BUFKIT PROFILES.
MEAN SNOWFALL FOR WARREN CTY IS IN THE 3-6 INCH RANGE...WHILE 2-4
INCHES IS LIKELY ACROSS THE NW HALF OF MCKEAN COUNTY/.
THE NAM IMPLIES AN EXTENSIVE QUASI-SINGLE BAND STRUCTURE PENETRATING
FAR INLAND ACROSS THE NRN TIER COUNTIES...AND PERHAPS THROUGH
SULLIVAN CTY ON TWD THE POCONOS.
THIS SIMULATION AND THE RAP MAKE IT CLEAR BOTH FORECAST SYSTEMS
THINK THERE SHOULD BE A GOOD LES BAND IN SOUTHERN NY AND NW PA
OVERNIGHT TONIGHT.
OUTSIDE THE LES AND UPSLOPE SNOW AREAS...IT WILL BE A VERY COLD
EVENING AND OVERNIGHT WITH GUSTY WINDS...TO AROUND 30 MPH AT TIMES.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
WEAK RIDGING SLIDES OVER THE AREA BENEATH THE FAST WESTERLY FLOW
ALOFT. LAKE EFFECT SNOW SHOWERS WILL DECREASE IN INTENSITY AND
BECOME MORE MULTI-BANDED ACROSS THE NW MTNS IN THE MORNING...BEFORE
LIFTING NORTH AND DIMINISHING DURING THE AFTERNOON.
IT/LL BE QUITE COLD MONDAY WITH MAX TEMPS ONLY IN THE UPPER TEENS TO
LOWER 20S ACROSS THE MTNS...AND MID TO UPPER 20S IN THE SUSQ VALLEY.
THESE TEMPS WILL BE ABOUT 15F BELOW NORMAL.
SIGNIFICANT BREAKS IN THE STRATO CU WILL DEVELOP ACROSS THE CENTRAL
AND SE ZONES MONDAY WHILE SKY COVER STAYS BKN-OVC ACROSS THE LAURELS
AND NW MTNS DUE TO LLVL UPSLOPE FLOW AND THICKER MID/HIGH CLOUDS
SPREADING IN LATE AHEAD OF A POTENT CLIPPER.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
THE GEFS-CMCEPS-SREF ALL SHOWS A CLIPPER PASSING TO OUR NORTH
TUESDAY. TIMING VARIES AND TRACK IS TO OUR NORTH THUS ANY
PRECIPITATION SHOULD BE LIGHT. TRIED TO SHOW THE POTENTIAL FOR
LIGHT SNOW TUESDAY. KEPT SNOW GENERALLY LOWER THAN 1 INCH AND
MAINLY CENTRAL AND NORTHERN AREAS.
THE NW FLOW WEAKENS AS A 500 HPA LOW DEVELOPS IN SW US LATER IN
THE WEEK. THIS ALLOWS FOR SOUTHWESTERLY FLOW AND A GRADUAL WARM UP
LIKELY THURSDAY INTO FRIDAY. MODELS IMPLY WARMEST DAY WOULD BE
FRIDAY. THIS WILL NOT LAST AS MODELS SHOWS DEEPENING TROUGH TO OUR
NORTH AND WEST AND A POOL OF ARCTIC AIR MOVING INTO THE LAKES
FRIDAY INTO SATURDAY. THUS SURFACE COLD FRONT SHOULD PUSH COLD AIR
BACK INTO OUR REGION SOMETIME NEXT WEEKEND.
BIAS CORRECT GEFS AND NAEFS SUGGEST TROUGH AND GENERALLY COLD
WEATHER SETTLE BACK IN THIS COMING WEEKEND AND INTO THE CHRISTMAS
WEEK.
AT THIS TIME NO BIG STORMS IN THE ENSEMBLES.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
15/21Z...A FAST AND PERSISTENT WEST-NORTHWEST FLOW ALOFT WITH
A SERIES OF EMBEDDED CLIPPER SYSTEMS WILL RESULT IN WIDESPREAD
MVFR CIGS AND MVFR-IFR VISBYS AT BFD/JST...WITH OCNL MVFR-IFR
CONDS FURTHER EAST ACRS THE CENTRAL AND EASTERN AIRFIELDS. MUCH
OF THE AIRSPACE COULD SEE -SN AND ASSOCD MVFR TO IFR VIS MON NGT-
TUE NGT. IMPROVING CONDS SHOULD ARRIVE LATER WED INTO THUR AS HIGH
PRESSURE EXPANDS OVER THE REGION. ANOTHER FRONTAL SYSTEM SHOULD
ARRIVE BY FRIDAY WITH TEMPERATURES INITIALLY WARM ENOUGH FOR
RAIN.
OUTLOOK...
MON...MAINLY VFR CENTRAL/EAST. MVFR-IFR IN SHSN AT BFD/JST.
MON NITE-TUE NGT...WIDESPREAD LGT SNOW/REDUCED VSBYS POSSIBLE.
WED-THU...SHSN/REDUCED VSBYS WEST BCMG VFR. VFR ELSEWHERE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST MONDAY FOR PAZ005.
LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST MONDAY FOR PAZ004.
&&
$$
SYNOPSIS...LA CORTE/LAMBERT
NEAR TERM...LA CORTE/LAMBERT
SHORT TERM...LAMBERT
LONG TERM...GRUMM/CERU
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1132 PM CST FRI DEC 13 2013
.AVIATION...
FOR THE 06Z TAFS...NO SIGNIFICANT CHANGES FROM THE OVERALL
THINKING OF THE 00Z TAFS...SO THE PREVIOUS DISCUSSION HAS BEEN
LEFT APPENDED BELOW.
THE BIGGEST CHANGE WITH THE 06Z TAFS WAS TO LOWER VISIBILITIES OUT
AHEAD OF THE COLD FRONT. AREAS OF DENSE FOG WERE DEVELOPING OVER
MANY PARTS OF NORTH AND CENTRAL TEXAS...AND WILL LIKELY DEVELOP AT
AREA AIRPORTS BEFORE THE FRONT ARRIVES AT 10Z. LOWERED VSBYS THE
MOST AT KFTW AND KAFW AS IR SATELLITE OBSERVED MOSTLY CLEAR SKIES
OVER THESE SITES. FOR THE REMAINDER OF THE DFW AREA TAFS CONTINUE
TO FORECAST A DROP IN VSBYS AFTER MIDNIGHT. KDFW AND KDAL WERE
STILL REPORTING MVFR SURFACE VSBYS IN THE REMARKS OF THEIR
OBSERVATIONS...WHICH IS WHY THE TAFS START OUT THAT WAY DESPITE
VSBYS THAT LOOK LOWER IN THE ACTUAL OBSERVATION. KACT WAS ALREADY
SURROUNDED WITH DENSE FOG...AND THIS IS UNLIKELY TO CHANGE UNTIL
THE FRONT ARRIVES AT 12Z.
CAVANAUGH
.../PREVIOUS AVIATION DISCUSSION/...
FOR THE 00Z TAFS...FLIGHT CATEGORY RESTRICTIONS ASSOCIATED WITH AN
APPROACHING COLD FRONT AND ONGOING LIGHT RAINFALL ACROSS THE
REGION ARE THE PRIMARY FORECAST CONCERNS.
23 TO 00Z OBSERVATIONS WERE HOVERING AROUND HIGH IFR TO LOW MVFR
CONDITIONS ACROSS THE DFW METROPLEX. OPTED TO GO WITH IFR CIGS
WITH MVFR VSBYS TO START OFF THE TAFS AS FORECAST SOUNDINGS ALL
SHOW CIGS LOWERING FROM 00 TO 03Z. LIGHT RAINFALL WILL LIKELY
PERSIST THROUGH MIDNIGHT BEFORE DRY AIR STARTS TO BUILD OVER THE
REGION BEHIND AN EXITING UPPER LEVEL DISTURBANCE. LIGHT
RAIN/DRIZZLE CONCERNS THROUGH MIDNIGHT PROMPTED THE CONTINUATION
OF THE MVFR VSBYS FOR THE START OF THE FORECAST.
SURFACE LOW PRESSURE IS EXPECTED TO SWEEP EAST ACROSS THE REGION
JUST OUT AHEAD OF A COLD FRONT. THIS WILL CAUSE WINDS TO VEER AND
DROP IN INTENSITY FOR A FEW HOURS BEFORE THE COLD FRONT ARRIVES.
THIS DROP IN WIND SPEEDS MAY ALLOW FOR SOME SHALLOW GROUND FOG TO
DEVELOP...SO WENT AHEAD WITH IFR VSBYS FOR THE WINDOW IN BETWEEN
MIDNIGHT AND WHEN THE FRONT IS EXPECTED TO ARRIVE...OR AROUND 10Z.
FORECAST SOUNDINGS INDICATE IFR CIGS AND ARE INCONCLUSIVE ON FOG
POTENTIAL. THE RAP AND LAMP GUIDANCE CERTAINLY HIT THE FOG
POTENTIAL HARD...BUT WITH LOW STRATUS IN PLACE...RADIATIONAL
COOLING WILL BE STUNTED WHICH SHOULD GENERALLY PREVENT DENSE FOG
FROM DEVELOPING AROUND AREA AIRPORTS AFTER MIDNIGHT. AT THIS POINT
WILL WAIT AND SEE IF IT LOOKS LIKE SHALLOW/GROUND FOG IS GOING TO
BE MORE EXPANSIVE TONIGHT...IF SO WILL HIT THE FOG POTENTIAL AND
VISIBILITIES HARDER AT THE 03 OR 06Z TAF ISSUANCES.
BEHIND THE FRONT...WINDS ARE EXPECTED TO BE STRONG ENOUGH TO CAUSE
ANY FOG THAT MANAGES TO DEVELOP TO DISSIPATE QUICKLY. WENT AHEAD
WITH VFR VSBYS AFTER THE FRONTAL PASSAGE AS A RESULT. CIGS WILL
REMAIN IFR RIGHT AFTER THE FRONTAL PASSAGE...AND WILL RISE TO MVFR
AND EVENTUALLY VFR BY TOMORROW AFTERNOON AS DRIER AIR WORKS INTO
THE REGION.
CAVANAUGH
&&
.UPDATE...
WILL UPDATE FOR PATCHY DENSE FOG IN AREAS EAST OF A LINE FROM
LAMPASAS TO GRANBURY TO BOWIE...AND ISSUE ADVISORY. WILL ALSO END
THE PRECIP AT 10 PM BASED ON EXTRAPOLATION OF CURRENT SHOWERS IN
THE EAST. IN AREAS WITH ICE...THE 40 DEW POINT AIR AND THE 30
DEGREE ICE WILL AID IN FOG FORMATION...AND MANY OTHER AREAS JUST
RECEIVED RAIN WHICH WILL ALSO AID IN FOG FORMATION. THE FRONT
SHOULD INCREASE VISIBILITY STARTING BEFORE SUNRISE FROM NORTHWEST
TO SOUTHEAST. THE HEAT ISLAND WILL ALSO LIKELY KEEP VISIBILITIES
ABOVE ADVISORY CRITERIA IN THE MIDDLE OF THE DFW METROPLEX.
UPDATE OUT SHORTLY. 84
&&
.PREV DISCUSSION... /ISSUED 349 PM CST FRI DEC 13 2013/
WATER VAPOR LOOP SHOWS A WELL DEFINED SHORTWAVE MOVING INTO THE
TEXAS PANHANDLE NOW. NORTH TEXAS IS CURRENTLY LOCATED IN A REGION
OF STRONG LIFT...BUT DEEPER MOISTURE IS ALREADY BEING SHUNTED EAST
OF THE AREA AS A DRY SLOT ALOFT WORKS THROUGH FROM THE SOUTHWEST.
HOWEVER THE LOW LEVELS REMAIN MOIST AND SATURATED AND THIS LIFT
WILL CONTINUE TO RESULT IN SCATTERED LOW TOPPED SHOWERS AND PATCHY
DRIZZLE OVER THE NEXT FEW HOURS. MUCH OF THIS ACTIVITY WILL END AS
THE BEST LIFT MOVES EAST OF THE CWA...AND FIRST PERIOD POPS WHICH
BEGIN AFTER 6PM WILL BE ON THE LOW SIDE FOR THE CENTRAL/WESTERN
CWA. A SECOND STRONG SHORTWAVE RIGHT ON THE HEELS OF THE FIRST
WILL APPROACH THE AREA LATE TONIGHT WHICH WILL ENSURE SOUTHERLY
WINDS THIS EVENING AND WARM/MOIST ADVECTION NEAR OR JUST ABOVE THE
SURFACE. THE WINDS AND WARM ADVECTION WILL LIKELY LIMIT THE
POTENTIAL FOR FOG TONIGHT...DESPITE A VERY FAVORABLE PROFILE...BUT
MAY ENHANCE THE POTENTIAL FOR LOW CLOUDS AND DRIZZLE. TEMPS WILL
LIKELY REMAIN NEARLY STEADY TONIGHT IN THE 40S AHEAD A COLD FRONT.
A SURFACE LOW AND COLD FRONT WILL MOVE THROUGH NORTH TEXAS AFTER 3
AM WITH WINDS BECOMING NORTH AT 15 MPH BY SUNRISE. STRONG
FRONTOGENETIC LIFTING OF A SATURATED LAYER NEAR THE SURFACE WILL
RESULT IN WIDESPREAD LOW CLOUDS AND SOME DRIZZLE BEHIND THE FRONT
SATURDAY MORNING. CLOUDS WILL CLEAR FROM NORTHWEST TO SOUTHEAST
DURING THE MID-LATE AFTERNOON HOURS ON SATURDAY. DUE TO THE CLOUDS
AND COLD ADVECTION BEHIND THE FRONT HIGHS SATURDAY WILL LIKELY
REMAIN IN THE LOW TO MID 40S. HOWEVER RADIATIONAL COOLING LOOK
GOOD SATURDAY NIGHT WITH LOWS FALLING INTO THE 20S AREA WIDE.
A GRADUAL MODERATION IN TEMPERATURES IS EXPECTED SUNDAY INTO THE
MIDDLE OF NEXT WEEK. GENERALLY CLEAR SKIES AND DRY AIR WILL ALLOW
FOR WARMER/MILD DAYS AND COOL NIGHTS. HIGHS SUNDAY WILL BE IN THE
50S FOR MOST AREAS...BUT 60S ARE EXPECTED MONDAY AND BEYOND. BY
WEDNESDAY SOUTHERLY WINDS WILL INCREASE AND BEGIN TO BRING HIGHER
DEWPOINTS INTO THE AREA WITH LOWS WELL ABOVE NORMAL IN THE 50S.
MEANWHILE...ANOTHER ARCTIC AIRMASS WILL BE GATHERING ACROSS CANADA
AS A POLAR VORTEX TRACKS FROM SIBERIA...ACROSS THE NORTH
POLE...AND INTO THE HUDSON BAY AREA BY NEXT WEEKEND. THIS UPPER
LEVEL PATTERN WILL RESULT IN ANTI-CYCLOGENESIS AND THE DEVELOPMENT
OF AN INTENSE ARCTIC HIGH PRESSURE CELL THAT DROPS INTO THE PLAINS
BY THURSDAY. THIS FRONT WOULD LIKELY TRACK THROUGH NORTH TEXAS ON
FRIDAY WITH TEMPERATURES AGAIN FALLING TO WELL BELOW NORMAL NEXT
WEEKEND. WE HAVE SEEN THE MODELS WAFFLE A BIT ON JUST HOW COLD
THIS AIRMASS WILL BE OVER THE LAST FEW DAYS FOR NORTH TEXAS. WHILE
THIS WILL SURELY BE ANOTHER NOTEWORTHY COLD SNAP FOR MUCH OF THE
COUNTRY...AS FAR AS NORTH TEXAS IS CONCERNED...THE MODELS ARE NOT
FORECASTING AN UPPER LEVEL PATTERN THAT WOULD RESULT IN ANY TYPE
OF RECORD BREAKING COLD HERE. AT THIS POINT I DONT SEE ANY
COMPELLING REASON TO BELIEVE THIS WILL BE ANY COLDER THAN OUR LAST
ARCTIC SPELL. THIS IS BECAUSE ALL MODELS HAVE BEEN VERY CONSISTENT
ON STRONG SURFACE LOW CYCLOGENESIS ACROSS THE PLAINS AND GREAT
LAKES WHICH WILL SERVE TO KEEP THE UPPER LEVEL LONGWAVE TROUGH
MORE PROGRESSIVE. PROGRESSIVE LONGWAVE TROUGHS DONT LET AS MUCH
COLD AIR DROP THIS FAR SOUTH AS SLOW MOVING OR STATIONARY UPPER
TROUGHS DO. ESSENTIALLY IN THIS UPPER LEVEL PATTERN...THE CORE OF
THE COLD AIR ENDS UP HEADING MORE EAST THAN SOUTH ONCE IT ARRIVES
INTO THE PLAINS AND MIDWEST.
CONCERNING WINTER PRECIP POTENTIAL...THERE IS STILL A TREMENDOUS
AMOUNT OF UNCERTAINTY WITH THE SHORTER WAVELENGTH FEATURES THAT
WOULD POSSIBLY PROVIDE THE LIFT AND MOISTURE REQUIRED FOR POST
FRONTAL WINTER PRECIP. IT WILL CERTAINLY BE COLD ENOUGH OVER NORTH
TEXAS FOR WINTER PRECIP AND LIKELY SNOW BY SATURDAY. THE KEY AT
THIS POINT IS VERY WEAK SHORTWAVE TROUGH THAT IS CURRENTLY OVER
JAPAN. THIS SYSTEM IS FORECAST TO REMAIN A RATHER INNOCUOUS POCKET
OF POTENTIAL VORTICITY FOR THE NEXT SEVERAL DAYS AS IT TRACKS
ACROSS THE PACIFIC...BUT IS FORECAST TO AMPLIFY/INTENSIFY AS IT
ARRIVES INTO THE PACIFIC NORTHWEST WEDNESDAY AND THURSDAY. THE 12Z
GFS/CANADIAN PHASE THIS ENERGY INTO THE BROADER LONGWAVE TROUGH...
AND SUGGEST ALL PRECIP WILL END BEFORE THE AIR GETS COLD ENOUGH
FOR SNOW. THE ECMWF AND SEVERAL GFS ENSEMBLE MEMBERS INDICATE
THAT THE ENERGY WITH THIS SYSTEM WILL REMAIN DETACHED FROM THE
MAIN UPPER TROUGH AND FORM INTO A CLOSED UPPER LOW WHICH TRACKS
OVER THE REGION SATURDAY. THIS SOLUTION WOULD RESULT IN A CHANCE
OF SNOW...ESPECIALLY OVER THE NORTHWEST/NORTHERN ZONES SATURDAY.
RIGHT NOW BASED ON ALL ENSEMBLE AND AVAILABLE OPERATIONAL RUNS WE
WOULD ESTIMATE THE CHANCE OF SNOW IN PART OF OUR CWA NEXT
SATURDAY AT 20 PERCENT. OF COURSE AT THIS TIME RANGE THERE IS
PLENTY OF TIME FOR MODELS TO TREND IN EITHER DIRECTION...SO WE
WILL HAVE TO WAIT AND SEE.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 40 43 29 54 35 / 10 10 0 0 0
WACO, TX 38 45 28 55 30 / 10 10 0 0 0
PARIS, TX 37 43 26 49 31 / 20 10 0 0 0
DENTON, TX 39 43 24 54 30 / 10 10 0 0 0
MCKINNEY, TX 39 42 25 52 28 / 20 10 0 0 0
DALLAS, TX 40 42 30 53 37 / 10 10 0 0 0
TERRELL, TX 40 43 27 52 30 / 20 10 0 0 0
CORSICANA, TX 41 44 28 53 34 / 20 10 0 0 0
TEMPLE, TX 39 46 29 56 30 / 10 10 0 0 0
MINERAL WELLS, TX 37 44 25 58 30 / 5 10 0 0 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 8 AM CST SATURDAY FOR TXZ091>095-
102>107-117>123-131>135-143>148-156>162-174-175.
&&
$$
/
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1235 PM EST SAT DEC 14 2013
.SYNOPSIS...
A COMPLEX LOW PRESSURE SYSTEM OVER THE LOWER MISSISSIPPI VALLEY
WILL MOVE NORTHEAST TODAY AND INTO THE CENTRAL APPALACHIANS BY
THIS EVENING. THE LOW DEEPENS AND MOVES OFF THE NEW ENGLAND COAST
BY SUNDAY MORNING. HIGH PRESSURE WILL BE OVER THE REGION MONDAY
AND TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM EST SATURDAY...
ADDED MORE SNOW ACROSS THE NORTHWEST TO MATCH UP WITH BAND OF
SNOW LIFTING NORTHWEST. WITH TEMPERATURES NEAR FREEZING...PLACED
SOME FREEZING RAIN ALONG THE SOUTHERN BLUE RIDGE. MODIFIED
TEMPERATURES AND DEW POINTS FOR LATEST OBS AND MODEL TRENDS.
SEE LATEST PNS FOR SNOW AMOUNTS. MORE CHANGES THIS AFTERNOON...
AS OF 925 AM EST SATURDAY...
FIRST BAND OF SNOW EARLY THIS MORNING PRODUCED A LIGHT COATING TO
AROUND ONE INCH ACROSS THE NORTH....WHILE SCATTERED SHOWERS FELL
IN A FEW LOCATIONS. MIX BATCH OF PRECIPITATION ENTERING PORTION
OF CWA THIS MORNING. RECEIVED REPORTS OF SOME SLEET NEAR
INDEPENDENCE IN GRAYSON COUNTY AND ALSO NEAR LYH. HRRR AND
RNKWRFARW SHOWED PRECIPITATION STARTING IN THE SOUTHWEST
SPREADING NORTHEAST ACROSS THE REGION THIS MORNING INTO THIS
AFTERNOON. LOOKING AT TEMPERATURES PROFILES LOOKS LIKE A PERIOD OF
SNOW AND SLEET STILL APPEARS POSSIBLE ESPECIALLY DURING THE ONSET
IN THE SOUTH BEFORE CHANGING TO RAIN. MADE SOME ADJUSTMENTS TO
TEMPERATURES AND DEW POINTS WITH LATEST OBS AND TRENDS. ADDED SOME
FOG FOR THIS MORNING. WITH ACTIVE WEATHER EXPECT MORE CHANGES
LATER THIS MORNING.
AS OF 500 AM EST SATURDAY...
BAND OF SNOW...WELL AHEAD OF THE MAIN AREA OF SYNOPTIC LIFT WAS
MOVING NORTHEAST OUT OF THE COUNTY WARNING AREA AT 5AM. THIS WAS
THE BEGINNING OF THE BREAK IN PRECIPITATION. CLOUD HEIGHTS WERE
STILL LOWERING AND RETURNS ON THE RADAR SHOWED THE PRECIPITATION
THAT WAS AIDING IN THE SATURATION OF THE AIR MASS.
HRRR...LOCAL WRF AND BUFKIT WERE SIMILAR WITH THE TIMING OF THE
MAIN BATCH OF PRECIPITATION...STARTING IN THE SOUTHWEST COUNTY
WARNING AREA BY 9AM AND REACHING THE NORTHEAST COUNTIES BY NOON.
DURATION OF PRECIPITATION WILL BE LIMITED...WITH A WELL DEFINED
DRY SLOT SEEN ON THE NATIONAL RADAR MOSAIC. EXPECT DRY SLOT AND
END OF MUCH OF THE PRECIPITATION TO REACH THE WESTERN COUNTY
WARNING AREA DURING THE MID AFTERNOON...WITH THE PRECIPITATION
ENDING IN THE EAST BY 9PM.
STRONG ISENTROPIC LIFT WILL RESULT IN SOME DECENT PRECIPITATION
RATES. MODELS WERE SHOWING SOME DIABATIC COOLING DURING THE
AFTERNOON NORTH OF ROUTE 460. THIS WILL IMPACT PRECIPITATION TYPE.
EVEN WITH EVAPORATIVE COOLING BRINING THE THERMAL PROFILE BELOW
ZERO...BUFKIT SHOWED A WEAK WARM NOSE FOR MUCH OF THE DAY. HAVE
MORE SLEET IN THE FORECAST THAN EARLIER WHICH WILL LIMIT
ACCUMULATIONS BUT IF PRECIPITATION IS HEAVY ENOUGH...IT WOULD STAY
AS SNOW. BY AFTERNOON TEMPERATURES ALOFT ARE WARM ENOUGH TO SUPPORT
FREEZING RAIN. ALSO BY THEN THE DEPTH OF THE MOISTURE WILL
GRADUALLY BECOME TOO SHALLOW FOR CRYSTAL GROWTH.
STRONG FLOW OFF THE GULF OF MEXICO BRINGS PRECIPITABLE WATER
VALUES BACK ABOVE ONE HALF INCH. HAVE INCREASED AMOUNT OF RAIN IN
THE SOUTHEAST COUNTY WARNING AREA WHERE PRECIPITABLE WATER VALUES
ARE HIGHER. NET RESULT WAS NO CHANGE IN ADVISORY AREA OR TIMING.
NON-DIURNAL TEMPERATURE TREND EXPECTED TODAY AS ONSET OF
PRECIPITATION INITIALLY COOLS SURFACE TEMPERATURES. COLDER AIR
COMES IN TONIGHT AS THE SURFACE LOW DEEPENS OFF THE MID ATLANTIC
COAST AND BRINGS THE WIND AROUND TO THE WEST. UPSLOPE SNOW
SHOWERS WILL PERSIST IN THE FAVORED AREAS OF SOUTHEAST WEST
VIRGINIA.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 345 AM EST SATURDAY...
SHORT TERM PERIOD OF FORECAST WILL BE RATHER UNEVENTFUL AS BROAD
UPPER TROF REMAINS ANCHORED OVER THE UPPER GREAT LAKES. COLD WEST
TO NORTHWEST UPSLOPING WINDS SHOULD MAINTAIN ABUNDANT CLOUD COVER
AND THREAT FOR OCCASIONAL LIGHT SNOW SHOWERS WITH SPOTTY LIGHT
ACCUMULATIONS ACROSS THE WESTERN FLANKS OF THE APPALACHIANS SUNDAY
INTO MONDAY BEFORE FINALLY ABATING BY MONDAY NIGHT AS SURFACE RIDGE
MOVES SOUTHEAST OF THE AREA...ENDING UPSLOPING MOIST FETCH FROM OFF
THE UPPER GREAT LAKES AS SURFACE WINDS BACK INTO THE SOUTHWEST.
TEMPERATURES IN THE UPSLOPE AREAS WILL BE HARD PRESSED TO CLIMB MUCH
ABOVE FREEZING THROUGH THE ENTIRE SHORT TERM PERIOD DUE TO COOLING
FROM FORCED ASCENT AND PERSISTENT CLOUD COVER. HAVE MAINTAINED
PREVIOUS FORECAST THINKING OF GOING A BIT BELOW MOS GUIDANCE DURING
DAYTIME PERIODS...WHICH TYPICALLY OVERESTIMATES THE EXTENT OF
DAYTIME WARMING UNDER THESE CONDITIONS.
ELSEWHERE...ESPECIALLY IN DOWNSLOPING AREAS EAST OF THE BLUE RIDGE
WHERE SKIES WILL REMAIN MOSTLY CLEAR THROUGH THE ENTIRE PERIOD...
DAYTIME HIGHS LIKELY TO CLIMB WELL INTO THE 40S TO LOWER 50S...AND
MOS GUIDANCE GENERALLY ACCEPTED IN THESE AREAS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 335 PM EST FRIDAY...
UNDER ZONAL FLOW AND SOUTHWEST FLOW...THE FORECAST AREA WILL WARM UP
TO NORMAL LEVELS TUESDAY. THE COLD FRONT...WHICH WILL BE MOVING
ACROSS THE OHIO VALLEY TUESDAY...IS A LITTLE SLOWER ON THE 12Z MODEL
RUNS. DESPITE IT BEING SLOWER...STILL LOOKING AT A MOSTLY DRY
FRONTAL PASSAGE AS HIGH PRESSURE BLOCKS MOISTURE RETURNS FROM THE
GULF. MODELS CONTINUE TO ADVERTISE UPSLOPE SNOW SHOWERS FOR WESTERN
GREENBRIER NORTHWARD FOLLOWING THE FRONTAL PASSAGE AND WITH A SHORT
WAVE TRACKING ACROSS THE CENTRAL APPALACHIANS TUESDAY NIGHT...TAPER
TO FLURRIES WEDNESDAY MORNING. A PRESSURE GRADIENT ALSO TIGHTENS
OVER THE AREA TUESDAY NIGHT INTO WEDNESDAY TO BRING WINDY/GUSTY
CONDITIONS TO THE AREA. A SUBSIDENCE INVERSION SHOULD KEEP THE
HIGHER WINDS ABOVE 3 KFT TUESDAY NIGHT. AS THE INVERSION BREAKS AND
CLOUDS ERODE WEDNESDAY...MIXING ACROSS THE ENTIRE FORECAST AREA IS
EXPECTED. WINDS ACROSS THE HIGHER ELEVATIONS MAY REACH WIND ADVISORY
CRITERIA. HIGH PRESSURE BUILDS OVER THE REGION WEDNESDAY NIGHT...
ALLOWING THE WINDS TO SUBSIDE. HIGH PRESSURE WILL THEN MOVE OFF THE
MID ATLANTIC COAST ON FRIDAY. THIS WILL ALLOW THE NEXT SYSTEM TO
APPROACH THE REGION NEXT WEEKEND.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 1235 PM EST SATURDAY...
POOR FLYING CONDITIONS EXPECTED DURING THE PERIOD WITH
WINTERY MIX OF RAIN...FREEZING RAIN...SNOW AND SLEET FALLING
ACROSS THE REGION THIS AFTERNOON INTO TONIGHT. IN
GENERAL...CONDITIONS ARE MVFR WITH LOCALIZED IFR/LIFR IN HEAVY
BANDS OF PRECIPITATION.
AS THE LOW MOVES OFFSHORE...WINDS WILL TURN TO THE WEST. THIS
WILL LEAD TO UPSLOPE IFR TO LIFR CLOUDS AND PRECIPITATION AT
KBLF/KLWB. CEILINGS WILL GRADUALLY LIFT EAST OF THE BLUE
RIDGE...BUT CLOUDS MAY NOT BECOME SCATTERED UNTIL AFTER THE 12Z.
THE UPSLOPE CLOUDS WILL HOLD IN OVER SOUTHEAST WEST VIRGINIA
THROUGH SUNDAY NIGHT.
MEDIUM CONDIFENCE IN CEILINGS AND VISIBILITIES DURING THE
TAF PERIOD. HIGH CONFIDENCE IN WIND DURING THE PERIOD.
HIGH PRESSURE EXPECTED TO BUILD INTO THE REGION FROM THE WEST
SUNDAY NIGHT INTO MONDAY...ALLOWING UPSLOPING CLOUDS TO GRADUALLY
ERODE OVER THE MOUNTAINS...BRINGING A RETURN TO VFR WEATHER WITH
UNRESTRICTED CONDITIONS...EVEN IN THE UPSLOPE AREAS...BY MIDDAY
MONDAY. DRY WEATHER WITH MAINLY VFR WEATHER IS THEN EXPECTED IN
MOST AREAS INTO MID WEEK...WITH PERHAPS THE EXCEPTION OF A PERIOD
OF SOME UPSLOPING CLOUDS WITH MVFR CEILINGS ACROSS THE WESTERN
FLANKS OF THE APPALACHIANS LATER TUESDAY INTO WEDNESDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY UNTIL 1 AM EST SUNDAY FOR VAZ018>020-
023-024-034-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY UNTIL 1 AM EST SUNDAY FOR WVZ044-045.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/KK
SHORT TERM...WERT
LONG TERM...RCS
AVIATION...AMS/WERT/KK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
925 AM EST SAT DEC 14 2013
.SYNOPSIS...
A COMPLEX LOW PRESSURE SYSTEM OVER THE LOWER MISSISSIPPI VALLEY
WILL MOVE NORTHEAST TODAY AND INTO THE CENTRAL APPALACHIANS BY
THIS EVENING. THE LOW DEEPENS AND MOVES OFF THE NEW ENGLAND COAST
BY SUNDAY MORNING. HIGH PRESSURE WILL BE OVER THE REGION MONDAY
AND TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 925 AM EST SATURDAY...
FIRST BAND OF SNOW EARLY THIS MORNING PRODUCED A LIGHT COATING TO
AROUND ONE INCH ACROSS THE NORTH....WHILE SCATTERED SHOWERS FELL
IN A FEW LOCATIONS. MIX BATCH OF PRECIPITATION ENTERING PORTION
OF CWA THIS MORNING. RECEIVED REPORTS OF SOME SLEET NEAR
INDEPENDENCE IN GRAYSON COUNTY AND ALSO NEAR LYH. HRRR AND
RNKWRFARW SHOWED PRECIPITATION STARTING IN THE SOUTHWEST
SPREADING NORTHEAST ACROSS THE REGION THIS MORNING INTO THIS
AFTERNOON. LOOKING AT TEMPERATURES PROFILES LOOKS LIKE A PERIOD OF
SNOW AND SLEET STILL APPEARS POSSIBLE ESPECIALLY DURING THE ONSET
IN THE SOUTH BEFORE CHANGING TO RAIN. MADE SOME ADJUSTMENTS TO
TEMPERATURES AND DEW POINTS WITH LATEST OBS AND TRENDS. ADDED SOME
FOG FOR THIS MORNING. WITH ACTIVE WEATHER EXPECT MORE CHANGES
LATER THIS MORNING.
AS OF 500 AM EST SATURDAY...
BAND OF SNOW...WELL AHEAD OF THE MAIN AREA OF SYNOPTIC LIFT WAS
MOVING NORTHEAST OUT OF THE COUNTY WARNING AREA AT 5AM. THIS WAS
THE BEGINNING OF THE BREAK IN PRECIPITATION. CLOUD HEIGHTS WERE
STILL LOWERING AND RETURNS ON THE RADAR SHOWED THE PRECIPITATION
THAT WAS AIDING IN THE SATURATION OF THE AIR MASS.
HRRR...LOCAL WRF AND BUFKIT WERE SIMILAR WITH THE TIMING OF THE
MAIN BATCH OF PRECIPITATION...STARTING IN THE SOUTHWEST COUNTY
WARNING AREA BY 9AM AND REACHING THE NORTHEAST COUNTIES BY NOON.
DURATION OF PRECIPITATION WILL BE LIMITED...WITH A WELL DEFINED
DRY SLOT SEEN ON THE NATIONAL RADAR MOSAIC. EXPECT DRY SLOT AND
END OF MUCH OF THE PRECIPITATION TO REACH THE WESTERN COUNTY
WARNING AREA DURING THE MID AFTERNOON...WITH THE PRECIPITATION
ENDING IN THE EAST BY 9PM.
STRONG ISENTROPIC LIFT WILL RESULT IN SOME DECENT PRECIPITATION
RATES. MODELS WERE SHOWING SOME DIABATIC COOLING DURING THE
AFTERNOON NORTH OF ROUTE 460. THIS WILL IMPACT PRECIPITATION TYPE.
EVEN WITH EVAPORATIVE COOLING BRINING THE THERMAL PROFILE BELOW
ZERO...BUFKIT SHOWED A WEAK WARM NOSE FOR MUCH OF THE DAY. HAVE
MORE SLEET IN THE FORECAST THAN EARLIER WHICH WILL LIMIT
ACCUMULATIONS BUT IF PRECIPITATION IS HEAVY ENOUGH...IT WOULD STAY
AS SNOW. BY AFTERNOON TEMPERATURES ALOFT ARE WARM ENOUGH TO SUPPORT
FREEZING RAIN. ALSO BY THEN THE DEPTH OF THE MOISTURE WILL
GRADUALLY BECOME TOO SHALLOW FOR CRYSTAL GROWTH.
STRONG FLOW OFF THE GULF OF MEXICO BRINGS PRECIPITABLE WATER
VALUES BACK ABOVE ONE HALF INCH. HAVE INCREASED AMOUNT OF RAIN IN
THE SOUTHEAST COUNTY WARNING AREA WHERE PRECIPITABLE WATER VALUES
ARE HIGHER. NET RESULT WAS NO CHANGE IN ADVISORY AREA OR TIMING.
NON-DIURNAL TEMPERATURE TREND EXPECTED TODAY AS ONSET OF
PRECIPITATION INITIALLY COOLS SURFACE TEMPERATURES. COLDER AIR
COMES IN TONIGHT AS THE SURFACE LOW DEEPENS OFF THE MID ATLANTIC
COAST AND BRINGS THE WIND AROUND TO THE WEST. UPSLOPE SNOW
SHOWERS WILL PERSIST IN THE FAVORED AREAS OF SOUTHEAST WEST
VIRGINIA.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 345 AM EST SATURDAY...
SHORT TERM PERIOD OF FORECAST WILL BE RATHER UNEVENTFUL AS BROAD
UPPER TROF REMAINS ANCHORED OVER THE UPPER GREAT LAKES. COLD WEST
TO NORTHWEST UPSLOPING WINDS SHOULD MAINTAIN ABUNDANT CLOUD COVER
AND THREAT FOR OCCASIONAL LIGHT SNOW SHOWERS WITH SPOTTY LIGHT
ACCUMULATIONS ACROSS THE WESTERN FLANKS OF THE APPALACHIANS SUNDAY
INTO MONDAY BEFORE FINALLY ABATING BY MONDAY NIGHT AS SURFACE RIDGE
MOVES SOUTHEAST OF THE AREA...ENDING UPSLOPING MOIST FETCH FROM OFF
THE UPPER GREAT LAKES AS SURFACE WINDS BACK INTO THE SOUTHWEST.
TEMPERATURES IN THE UPSLOPE AREAS WILL BE HARD PRESSED TO CLIMB MUCH
ABOVE FREEZING THROUGH THE ENTIRE SHORT TERM PERIOD DUE TO COOLING
FROM FORCED ASCENT AND PERSISTENT CLOUD COVER. HAVE MAINTAINED
PREVIOUS FORECAST THINKING OF GOING A BIT BELOW MOS GUIDANCE DURING
DAYTIME PERIODS...WHICH TYPICALLY OVERESTIMATES THE EXTENT OF
DAYTIME WARMING UNDER THESE CONDITIONS.
ELSEWHERE...ESPECIALLY IN DOWNSLOPING AREAS EAST OF THE BLUE RIDGE
WHERE SKIES WILL REMAIN MOSTLY CLEAR THROUGH THE ENTIRE PERIOD...
DAYTIME HIGHS LIKELY TO CLIMB WELL INTO THE 40S TO LOWER 50S...AND
MOS GUIDANCE GENERALLY ACCEPTED IN THESE AREAS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 335 PM EST FRIDAY...
UNDER ZONAL FLOW AND SOUTHWEST FLOW...THE FORECAST AREA WILL WARM UP
TO NORMAL LEVELS TUESDAY. THE COLD FRONT...WHICH WILL BE MOVING
ACROSS THE OHIO VALLEY TUESDAY...IS A LITTLE SLOWER ON THE 12Z MODEL
RUNS. DESPITE IT BEING SLOWER...STILL LOOKING AT A MOSTLY DRY
FRONTAL PASSAGE AS HIGH PRESSURE BLOCKS MOISTURE RETURNS FROM THE
GULF. MODELS CONTINUE TO ADVERTISE UPSLOPE SNOW SHOWERS FOR WESTERN
GREENBRIER NORTHWARD FOLLOWING THE FRONTAL PASSAGE AND WITH A SHORT
WAVE TRACKING ACROSS THE CENTRAL APPALACHIANS TUESDAY NIGHT...TAPER
TO FLURRIES WEDNESDAY MORNING. A PRESSURE GRADIENT ALSO TIGHTENS
OVER THE AREA TUESDAY NIGHT INTO WEDNESDAY TO BRING WINDY/GUSTY
CONDITIONS TO THE AREA. A SUBSIDENCE INVERSION SHOULD KEEP THE
HIGHER WINDS ABOVE 3 KFT TUESDAY NIGHT. AS THE INVERSION BREAKS AND
CLOUDS ERODE WEDNESDAY...MIXING ACROSS THE ENTIRE FORECAST AREA IS
EXPECTED. WINDS ACROSS THE HIGHER ELEVATIONS MAY REACH WIND ADVISORY
CRITERIA. HIGH PRESSURE BUILDS OVER THE REGION WEDNESDAY NIGHT...
ALLOWING THE WINDS TO SUBSIDE. HIGH PRESSURE WILL THEN MOVE OFF THE
MID ATLANTIC COAST ON FRIDAY. THIS WILL ALLOW THE NEXT SYSTEM TO
APPROACH THE REGION NEXT WEEKEND.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
AS OF 715 AM EST SATURDAY...
CEILINGS WILL CONTINUE TO LOWER THIS MORNING AS MOISTURE INCREASES
AND A LOW PRESSURE SYSTEM OVER THE LOWER MISSISSIPPI VALLEY
APPROACHES FROM THE WEST. AS PRECIPITATION BEGINS...IT WILL COOL
AND MOISTEN THE AIR MASS WHICH WILL RESULT IN SNOW AND/OR SLEET
AT THE ONSET. AS SHOWN IN BUFKIT SOUNDINGS...THE PRECIPITATION
WILL BECOME PRIMARILY RAIN AT KROA/KDAN/KBCB/KBLF/KLYH BY
AFTERNOON BUT WILL STAY MOSTLY SNOW AT KLWB.
HIGH CONFIDENCE IN THE TIMING OF THE PRECIPITATION...MOVING IN
FROM THE WEST AROUND 8AM AND EXITING THE EAST AROUND 8PM. LESS
CONFIDENCE ABOUT THE EXACT PRECIPITATION TYPE...ESPECIALLY THIS
MORNING.
AS THE LOW MOVES OFFSHORE...WINDS WILL TURN TO THE WEST. THIS WILL
LEAD TO UPSLOPE IFR TO LIFR CLOUDS AND PRECIPITATION AT KBLF/KLWB.
CEILINGS WILL GRADUALLY LIFT EAST OF THE BLUE RIDGE...BUT CLOUDS
MAY NOT BECOME SCATTERED UNTIL AFTER THE 12Z END OF THE TAF
FORECAST PERIOD. THE UPSLOPE CLOUDS WILL HOLD IN OVER SOUTHEAST
WEST VIRGINIA THROUGH SUNDAY NIGHT.
HIGH PRESSURE EXPECTED TO BUILD INTO THE REGION FROM THE WEST
SUNDAY NIGHT INTO MONDAY...ALLOWING UPSLOPING CLOUDS TO GRADUALLY
ERODE OVER THE MOUNTAINS...BRINGING A RETURN TO VFR WEATHER WITH
UNRESTRICTED CONDITIONS...EVEN IN THE UPSLOPE AREAS...BY MIDDAY
MONDAY. DRY WEATHER WITH MAINLY VFR WEATHER IS THEN EXPECTED IN
MOST AREAS INTO MID WEEK...WITH PERHAPS THE EXCEPTION OF A PERIOD
OF SOME UPSLOPING CLOUDS WITH MVFR CEILINGS ACROSS THE WESTERN
FLANKS OF THE APPALACHIANS LATER TUESDAY INTO WEDNESDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY UNTIL 1 AM EST SUNDAY FOR VAZ018>020-
023-024-034-035.
NC...NONE.
WV...WINTER WEATHER ADVISORY UNTIL 1 AM EST SUNDAY FOR WVZ044-045.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/KK
SHORT TERM...WERT
LONG TERM...RCS
AVIATION...AMS/WERT
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1010 AM PST Sat Dec 14 2013
.SYNOPSIS...
A series of weak weather systems will clip the Inland Northwest
through Tuesday bringing a chance for light snow showers at times
for areas mainly near the Canadian border and Idaho Panhandle. On
Wednesday into Thursday a stronger system will bring better
chances for rain and snow. Temperatures are expected climb
slightly above normal through Wednesday before falling back to
below normal for the end of next week.
&&
.DISCUSSION...
Radar imagery as of 830 am showed a band of light rain and snow
associated with a warm front moving east into the Idaho Panhandle,
Coeur D`Alene area, Palouse, and Lewiston area. Snow levels have
risen with this front to around 3000 feet over the Idaho Panhandle
and around 5000 feet over the Blue Mountains. Forecast has been
updated based on these latest trends. This area of light
precipitation should only last for a few hours with latest GFS,
NAM, and HRRR showing little in the way of qpf after the warm
front exits this morning. However abundant low level moisture and
southwest winds at 850mb of 15-20 kts will likely result in some
lingering shower activity over the Idaho Panhandle and Northeast
Washington into the afternoon. Also a saturated boundary layer
over much of Eastern Washington and weak low level upslope
southerly winds into Spokane and the Upper Columbia Basin will
likely result in at least patchy fog lingering into the late
morning and afternoon so fog was extended in time in these areas. JW
&&
.AVIATION...
18Z TAFS: A saturated boundary layer over northeast Washington into
the Idaho Panhandle will result in conditions mainly IFR/MVFR
through the afternoon although some improvement is expected. KCOE
may improve to VFR before falling back to IFR conditions tonight.
Downslope southeast winds for KPUW-KLWS should result in CIGS
remaining VFR through 18z Sunday. For tonight into Sunday morning
there is an increased threat for stratus expanding west into Moses
Lake and Wenatchee aided by low level southeast winds. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 36 27 36 29 36 27 / 10 10 10 0 0 10
Coeur d`Alene 38 29 38 31 37 30 / 40 10 10 10 10 10
Pullman 39 30 41 31 40 29 / 60 10 10 0 0 0
Lewiston 41 34 42 33 40 31 / 30 10 10 0 0 0
Colville 36 28 36 28 35 27 / 30 20 10 10 10 20
Sandpoint 36 27 37 29 37 28 / 60 30 20 20 10 30
Kellogg 36 30 38 32 37 31 / 60 20 30 20 20 10
Moses Lake 35 24 38 26 37 25 / 10 10 0 0 0 0
Wenatchee 33 27 38 28 36 27 / 0 10 0 0 0 0
Omak 32 25 34 24 33 23 / 10 10 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
849 AM PST Sat Dec 14 2013
.SYNOPSIS...
A series of weak weather systems will clip the Inland Northwest
through Tuesday bringing a chance for light snow showers at times
for areas mainly near the Canadian border and Idaho Panhandle. On
Wednesday into Thursday a stronger system will bring better
chances for rain and snow. Temperatures are expected climb
slightly above normal through Wednesday before falling back to
below normal for the end of next week.
&&
.DISCUSSION...
Radar imagery as of 830 am showed a band of light rain and snow
associated with a warm front moving east into the Idaho Panhandle,
Coeur D`Alene area, Palouse, and Lewiston area. Snow levels have
risen with this front to around 3000 feet over the Idaho Panhandle
and around 5000 feet over the Blue Mountains. Forecast has been
updated based on these latest trends. This area of light
precipitation should only last for a few hours with latest GFS,
NAM, and HRRR showing little in the way of qpf after the warm
front exits this morning. However abundant low level moisture and
southwest winds at 850mb of 15-20 kts will likely result in some
lingering shower activity over the Idaho Panhandle and Northeast
Washington into the afternoon. Also a saturated boundary layer
over much of Eastern Washington and weak low level upslope
southerly winds into Spokane and the Upper Columbia Basin will
likely result in at least patchy fog lingering into the late
morning and afternoon so fog was extended in time in these areas. JW
&&
.AVIATION...
12Z TAFS: A weak frontal boundary is moving through eastern
Washington this morning and will bring brief rain and snow showers
to the eastern taf sites. This may/should mix up cigs for a short
period of time through 14-15z. Otherwise a saturated boundary layer
will result in conditions mainly IFR/LIFR through the morning. Some
improvement is expected this afternoon...but not much relief is
expected at KGEG-KSFF. KCOE may improve to VFR before falling back
to IFR conditions tonight. KPUW-KLWS mainly VFR but KPUW may see MVFR
conditions briefly this morning. Prevailing VFR conditions for
KMWH-KEAT through early afternoon...then things get quite
complicated as southeast flow should push boundary layer moisture
into this region this afternoon or early this evening. Not much
confidence in the forecast in this area for the last 12 hours...but
the expectation is for stratus development after 03z. /Tobin
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 36 27 36 29 36 27 / 10 10 10 0 0 10
Coeur d`Alene 38 29 38 31 37 30 / 40 10 10 10 10 10
Pullman 39 30 41 31 40 29 / 60 10 10 0 0 0
Lewiston 41 34 42 33 40 31 / 30 10 10 0 0 0
Colville 36 28 36 28 35 27 / 30 20 10 10 10 20
Sandpoint 36 27 37 29 37 28 / 60 30 20 20 10 30
Kellogg 36 30 38 32 37 31 / 60 20 30 20 20 10
Moses Lake 35 24 38 26 37 25 / 10 10 0 0 0 0
Wenatchee 33 27 38 28 36 27 / 0 10 0 0 0 0
Omak 32 25 34 24 33 23 / 10 10 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1010 AM CST SAT DEC 14 2013
.UPDATE...SNOW BANDS HAVE FINALLY DEVELOPED ACROSS FAR SE WI
WHICH IS REFLECTED THE BEST BY THE HRRR AND RAP. THESE MODELS
INDICATE SNOW WILL CONTINUE THROUGH AROUND NOON IN SOUTH-CENTRAL
AND EARLY AFTERNOON FOR THE LAKESHORE COUNTIES.
MID TO LOWER LEVEL FRONTOGENESIS CONTINUES TO CONTRIBUTE TO
FORCING INSTEAD OF MUCH LAKE EFFECT...ALTHOUGH LAKE ENHANCEMENT IS
PROBABLY PLAYING A ROLE...SO KEPT THE LAKE EFFECT SNOW ADVISORY
GOING. RAP AND NAM SOUNDINGS SHOW THE DENDRITE GROWTH ZONE REMAINS
SATURATED THROUGH MOST OF THE AFTERNOON...HOWEVER OMEGA QUICKLY
BECOMES POSITIVE AROUND MIDDAY AS UPPER TROUGH MOVES IN...WHICH
WILL HELP TO DIMINISH SNOW. WINDS WILL THEN TURN NORTHWEST IN THE
EVENING ENDING SNOW CHANCES AS THE SURFACE LOW MOVES INTO OHIO AND
UPPER TROUGH AXIS MOVES ACROSS E WI.
&&
.AVIATION/18Z TAFS/...LAKE EFFECT/ENHANCED SNOW WILL CONTINUE
THROUGH MUCH OF THE DAY...WINDING DOWN WEST TO EAST THIS AFTERNOON.
LATEST RADAR TRENDS SHOW AN OVERALL WEAKENING OF RETURNS...BUT AS
LONG AS THE FLOW REMAINS ONSHORE THERE WILL BE A THREAT OF HEAVIER
BANDS. VISIBILITIES WILL GENERALLY RANGE FROM 1 TO 3 MILES INTO
EARLY AFTERNOON...WITH IMPROVING CONDITIONS AS THE SNOW LETS UP.
COULD SEE SOME BRIEFLY LOWER VISIBILITIES WITHIN HEAVIER SNOW
BANDS. COULD SEE ANOTHER INCH OR SO OF SNOW THROUGH THE REST OF
THE DAY.
MAY SEE A LITTLE SNOW LINGER NORTH IN THE EVENING AND OVERNIGHT AS
THE UPPER TROUGH MOVES THROUGH...BUT OTHERWISE SHOULD BE DRY THEN
THROUGH SUNDAY. MVFR CIGS MAY HANG AROUND THROUGH THE NIGHT AND
INTO SUNDAY...WITH VFR CONDITIONS PROBABLY RETURNING BY AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 346 AM CST SAT DEC 14 2013/
SHORT TERM...
TODAY-FORECAST CONFIDENCE HIGH
FRONTOGENESIS IN RIGHT ENTRANCE REGION OF 140 KNOT 250 MB JET HAS
SLOWLY HELPED MOISTEN COLUMN DURING THE NIGHT...BUT SIGNIFICANT
PRECIPITATION HAS BEEN SLOWER TO DEVELOP THAN MOST OF THE MODEL
GUIDANCE SUGGESTED GOING INTO THE EVENT. IR SHOWS CLOUD TOPS
COOLING INTO -40 TO -50C RANGE FROM CENTRAL IOWA INTO SOUTHERN
WISCONSIN. NARROW FRONTOGENESIS BAND FROM KPVB TO JUST SOUTH OF
KMSN TO KMWC HAS PRODUCED LIGHT SNOW THUS FAR MAINLY NEAR THE SHORE.
TMKE SHOWS LIGHT MULTI-BAND LAKE EFFECT SNOW SHOWERS MOVING ONSHORE
IN EASTERLY FLOW REGIME. THIS SHOULD CONTINUE WELL INTO THE
AFTERNOON AND EXPECT COVERAGE TO INCREASE FURTHER AS SEEDING FROM
MID LEVEL FRONTOGENESIS BANDS ENHANCES THE PRECIPITATION. CONSENSUS
OF AVAILABLE MODEL GUIDANCE CONTINUES TO SHOW QPF OF ABOUT 0.25"
NEAR THE SHORE ESPECIALLY NEAR MILWAUKEE COUNTY AREA...WHERE MID
LEVEL FRONTOGENESIS BAND IS SHOWN TO PIVOT OVER THE NEXT 12 HOURS.
THUS 3-5" SNOWFALL SUPPORTING LAKE EFFECT SNOW ADVISORY WITHIN 1-2
COUNTIES OF THE SHORE STILL LOOKS REASONABLE. ELSEWHERE UP TO 1-2"
SEEMS REASONABLE AS NORTHERN BRANCH TROUGH APPROACHES FROM MINNESOTA
WITH ASSOCIATED 70 METER 500 MB HEIGHT FALLS.
UPPER TROUGH MOVES THROUGH IN THE LATE AFTERNOON WITH LOW LEVEL FLOW
TURNING TO THE NORTHWEST RAPIDLY SO EXPECT CUTOFF IN PRECIPITATION
AROUND DARK.
TONIGHT-FORECAST CONFIDENCE HIGH
COLD NORTHWEST FLOW WITH GRADUALLY FALLING HEIGHTS EXPECTED.
CYCLONIC FLOW AND LINGERING BOUNDARY LAYER MOISTURE PROBABLY KEEPS
THINGS OVERCAST MUCH OF THE NIGHT SO NOT MUCH OPPORTUNITY FOR
RADIATION. THIS ESPECIALLY TRUE GIEVN 30 KNOT NORTHWEST FLOW AT 850
MB. SHOULD BE DRY.
SUNDAY THROUGH MONDAY NIGHT...FORECAST CONFIDENCE
IS MEDIUM.
DRY AIR CONTINUES TO SHIFT INTO THE REGION ON SUNDAY...AS WEST
NORTHWEST WINDS REMAIN. 500 MB VORTICITY MAXIMUM PASSES JUST NORTH
OF THE AREA...EXCEPT NAM WHICH CLIPS THE NORTHEAST PORTIONS OF THE
AREA. AREA FORECAST SOUNDINGS SHOWING SOME MID LEVEL CLOUDS MOVING
THROUGH THE REGION...WITH LOW LEVELS DRY. LEFT SUNDAY DRY...WITH
COLD TEMPERATURES CONTINUING PER 925 MB TEMPERATURE FIELDS.
KEPT SUNDAY NIGHT DRY AS WELL...WITH 500 MB VORTICITY MAXIMUM
REMAINING SOUTHWEST OF THE AREA. GFS/ECMWF/CANADIAN MODELS TRY TO
CLIP THE FAR SOUTHWEST COUNTIES WITH LIGHT QPF WITH THIS
FEATURE...BUT FORECAST SOUNDINGS ARE SHOWING ONLY SOME LOW
CLOUDS...WITH THE MID LEVELS DRY. TEMPERATURES WILL CONTINUE TO BE
COLD...WITH LOWS DROPPING INTO THE SINGLE DIGITS ABOVE ZERO.
MAINTAINED POPS FOR MONDAY AND MONDAY NIGHT ACROSS THE AREA. PUSH
OF WARM AIR ADVECTION OCCURS IN THE LOW LEVELS FOR
MONDAY...FOLLOWED BY A STRONG 500 MB VORTICITY MAXIMUM PASSING
THROUGH THE REGION MONDAY NIGHT. AREA FORECAST SOUNDINGS SHOW SOME
SATURATION IN THE AIR COLUMN MONDAY...WITH SOME DIFFERENCES
BETWEEN THE GFS AND NAM. THEY ARE SOMEWHAT DRY MONDAY NIGHT.
TEMPERATURES TRY TO MODERATE SOMEWHAT DURING THIS TIME.
LONG TERM...TUESDAY THROUGH SATURDAY...FORECAST CONFIDENCE IS
MEDIUM.
GFS/ECMWF SHOWING SOME AGREEMENT EARLY IN THE PERIOD...AS THEY
BRING A 500MB VORTICITY MAXIMUM THROUGH THE REGION ON TUESDAY.
AREA FORECAST SOUNDINGS FROM GFS ARE SOMEWHAT DRY...THOUGH DO HAVE
WEAK LOW LEVEL INSTABILITY. KEPT DRY FORECAST FOR NOW. HIGH
PRESSURE AXIS PASSES THROUGH THE REGION TUESDAY NIGHT INTO
WEDNESDAY...CONTINUING THE QUIET WEATHER. WARM AIR ADVECTION THEN
KICKS IN WEDNESDAY NIGHT...BUT AIRMASS IS FAIRLY DRY. TEMPERATURES
ARE STILL BELOW SEASONAL NORMALS.
GFS/ECMWF THEN BRING DEVELOPING LOW PRESSURE FROM THE CENTRAL HIGH
PLAINS TO NORTHERN LOWER MICHIGAN THURSDAY THROUGH THURSDAY
NIGHT...BEFORE HIGH PRESSURE RETURNS FOR FRIDAY INTO SATURDAY.
WARM AIR ADVECTION ON THE FRONT SIDE MAY LEAD TO A MIX OF
PRECIPITATION THURSDAY AFTERNOON AND EVENING...BEFORE COLD FRONT
MOVES THROUGH AND COOLS THINGS OFF. FOR NOW...USED CONSENSUS OF
MODELS FOR POPS AND TEMPERATURES IN THIS PERIOD.
AVIATION/12Z TAFS/...
COMBINATION OF LAKE EFFECT SNOW SHOWERS AND BANDS OF SYNOPTIC SCALE
SNOW SHOULD KEEP IFR CONDITIONS MUCH OF THE DAY ESPECIALLY OVER THE
SOUTHEAST WISCONSIN TAF SITES. ALTHOUGH SNOW HAS BEEN SLOW TO
DEVELOP AT KMSN THERE IS A FRONTOGENESIS BAND JUST SOUTH OF THE
AIRPORT THAT SHOULD EVENTUALLY WORK ITS WAY NORTH AND EXPAND DURING
THE MORNING.
NO BETTER THAN LOWER END MVFR CEILINGS OUTSIDE OF THE SNOW LATE THIS
AFTERNOON AND TONIGHT AS CLOUDS ARE EXPECTED TO LINGER AFTER SNOW
MOVES OUT AND FLOW TURNS FROM EASTERLY TO NORTHWEST.
&&
MARINE...
MODERATE EAST WINDS GENERATE WAVES UP TO 6 FEET THROUGH EARLY
AFTERNOON BEFORE WINDS TURN NORTHWEST. WINDS AND WAVES SUBSIDING
LATE THIS AFTERNOON AND EVENING SO EXPECT BRIEF RESPITE IN SMALL
CRAFT ADVISORY CONDITIONS TONIGHT.
WESTERLY WINDS MAY REACH SMALL CRAFT ADVISORY CRITERIA ON SUNDAY
BEHIND THE DEPARTING SYSTEM.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...LAKE EFFECT SNOW ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ052-
059-060-065-066-071-072.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS EVENING FOR LMZ643>646.
&&
$$
UPDATE...SM/DDV
TODAY/TONIGHT AND AVIATION/MARINE...CRAVEN
SUNDAY THROUGH FRIDAY...WOOD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
230 AM CST SAT DEC 14 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 230 AM CST SAT DEC 14 2013
TWO AREAS OF PCPN TO WATCH TODAY.
FIRST...THE ONE ACROSS IOWA/ILL THAT IS BEING DRIVEN BY AN UPPER
LEVEL SHORTWAVE TROUGH SPINNING TOWARD THE OH RIVER VALLEY. RADAR
AND MESO MODEL TRENDS ON THIS PCPN REGION ARE TO KEEP IT JUST SOUTH
OF THE FORECAST AREA.
SECOND...AREAS OF SNOW ACROSS MUCH OF MN/NORTHERN PLAINS TRACKING
EAST SOUTHEAST...WITH SOME LOW LEVEL THERMODYNAMIC FORCING AND A
SHORTWAVE TROUGH DROPPING SOUTH OUT OF SOUTHERN CANADA HAVING A HAND
IN ITS PRODUCTION. THIS WILL BE THE SNOW THAT FALLS ACROSS THE
FORECAST AREA TODAY...LIKELY LINGERING INTO THE EVENING HOURS AS THE
SHORTWAVE MAKES IT WAY ACROSS THE UPPER MISSISSIPPI RIVER VALLEY.
GENERALLY...IT LOOKS LIKE UP TO AN INCH OF FLUFFY ACCUMULATIONS FOR
MOST LOCATIONS...BUT UP TO 2 INCHES NORTH/EAST OF I-94 WHERE THE
SHORTWAVE INFLUENCE WILL BE FELT LONGER.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 230 AM CST SAT DEC 14 2013
A COUPLE UPPER LEVEL SHORTWAVES WILL TAKE AIM ON THE REGION AS THE
BUSY NORTHWEST FLOW CONTINUES. DECENT AGREEMENT BETWEEN THE
NAM/GFS/EC WITH SLIDING A BIT OF UPPER LEVEL ENERGY ACROSS MN/IA
SUNDAY NIGHT...WITH A STRONGER SHORTWAVE MOVING OVER NORTHERN WI
MONDAY AFTERNOON/NIGHT. LIGHT SNOW WOULD BE LIKELY WITH THESE UPPER
LEVEL FEATURES...BUT TIMING/POSITIONING IS PROBLEMATIC. WILL SIDE
WITH HIGH CHANCES FOR SNOW FOR NOW.
THE GFS AND ECMWF HAVE BEEN AT ODDS AT HOW TO HANDLE AN END OF THE
WORK WEEK LOW PRESSURE SYSTEM...BUT THEY ARE STARTING TO SHOW MORE
COMPATIBILITY WITH THEIR RECENT SOLUTIONS. TRENDS ARE FAVORING THE
FASTER...MORE NORTH SOLUTION THAT THE EC HAD BEEN ALLUDING TO...WITH
AN UPPER LEVEL SHORTWAVE SPINNING OUT OF THE SOUTHERN ROCKIES...TO
ACROSS THE SOUTHERN GREAT LAKES BY TOWARD 00Z FRI. THE ACCOMPANYING
SFC LOW TRACKS INTO SOUTHERN WI BY THIS TIME. STRONG SLUG OF LOW
LEVEL WARM AIR ADVECTION AND ISENTROPIC UPGLIDE AHEAD OF THE
SHORTWAVE. GOOD PUSH OF LOW LEVEL MOISTURE ADVECTION ALSO INDICATED
AS A 50 KT 850 MB JET POINTS INTO THE SOUTHERN GREAT LAKES. AMPLE
THERMODYNAMICS FOR PCPN PRODUCTION ON THU...WITH THE SHORTWAVE
ENHANCING THE PCPN BY 00Z FRI. CURRENT TRENDS WOULD SHIFT THE SYSTEM
TO THE EAST/NORTHEAST BY 12Z FRI.
OF INTEREST WITH THIS PCPN MAKER IS THAT PCPN TYPE WILL BE A
CONCERN. LATEST TIME/HEIGHT X-SECTIONS AND BUFKIT SOUNDINGS INDICATE
BOTH A NEAR SFC WARM LAYER...AND SHALLOW SATURATION ON THE FRONT END
OF THE LOW PRESSURE SYSTEM. BOTH WOULD RESULT IN LIQUID...AND
DEPENDING ON SFC TEMPS...SOME FREEZING PCPN COULD RESULT. SPEED/
TIMING/POSITIONING OF THE SYSTEM PUTS ACCUMULATING SNOWS IN QUESTION
TOO...AS IT MIGHT BE TOO WARM AND DOESN/T LINGER LONG ENOUGH FOR
COLD AIR TO WORK IN. GOING TO STICK WITH RAIN OR SNOW FOR PTYPES
NOW.
THE SYSTEM BEARS WATCHING MORE FOR THE PCPN TYPES RATHER THAN
AMOUNTS.
HIGH PRESSURE IS THE SLATED TO BUILD IN FROM THE PLAINS BY FRIDAY
NIGHT...STICKING AROUND ON SAT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1123 PM CST FRI DEC 13 2013
THE BAND OF MVFR CLOUDS MOVED BACK OVER BOTH TAF SITES AS EXPECTED
THIS EVENING AND NOW LOOKS LIKE IT WILL REMAIN THROUGH THE PERIOD.
THE THREAT FOR SOME SNOW WILL COME FROM THE SHORT WAVE TROUGH
APPROACHING FROM THE WEST. LIGHT SNOW IS FALLING AHEAD OF THIS WAVE
FROM WESTERN MINNESOTA INTO WISCONSIN WEST OF THE TWIN CITIES. AS
THE WAVE CONTINUES TO MOVE EAST...LOOK FOR THE LIGHT SNOW TO SLOWLY
MOVE SOUTHEAST AND SPREAD OVER THE TAF SITES DURING THE OVERNIGHT
HOURS. CONDITIONS ARE QUITE VARIABLE WITH THE SNOW...BUT ARE
PRIMARILY MVFR WITH SOME LOCATIONS REPORTING IFR CONDITIONS. THIS
CORRESPONDS WELL TO THE 14.00Z NAM AND 14.03Z RAP BUFKIT SOUNDINGS
FOR BOTH SITES AND WILL SHOW PREVAILING MVFR CONDITIONS IN THE LIGHT
SNOW WITH A PERIOD OF IFR POSSIBLE LATE TONIGHT INTO EARLY SATURDAY
MORNING. ONCE THE FORCING FROM THE MAIN WAVE MOVES PAST...THE NAM
SUGGEST SOME WEAK FRONTOGENESIS IN THE 1000-850 MB LAYER WILL LINGER
OVER EASTERN MINNESOTA INTO THE DAY AS THE NEXT NORTHERN STREAM
SHORT WAVE TROUGH MOVES ACROSS THE REGION. WILL THUS KEEP A MVFR
VISIBILITY INTO THE AFTERNOON BEFORE GOING TO FLURRIES AS THE
FRONTOGENESIS WEAKENS BY MID AFTERNOON.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION.....04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1123 PM CST FRI DEC 13 2013
.SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 205 PM CST FRI DEC 13 2013
WATER VAPOR LOOP/LATEST RUC 500MB ANALYSIS SHOWS A BROAD LONG WAVE
TROUGH ENCOMPASSING THE ENTIRE CONUS. WITHIN THIS LONG WAVE TROUGH
THERE ARE TWO MID-LEVEL SHORTWAVE TROUGHS THAT WILL EVENTUALLY
IMPACT THE AREA TONIGHT THROUGH SATURDAY EVENING. TROUGH NUMBER ONE
WAS MOVING EAST OUT OF MT/WY TOWARD THE NORTHERN PLAINS WHILE A MORE
POTENT TROUGH NUMBER TWO WAS MOVING EAST OUT OF CO/NM INTO THE
SOUTHERN PLAINS. AT THE SURFACE...THIS TRANSLATED TO AN AREA OF
CYCLOGENESIS OVER WESTERN KS WITH A WARM FRONT EXTENDING ALONG THE
IA/MO BORDER INTO CENTRAL IL. CURRENTLY...OUR LOCAL FORECAST AREA
WAS IN BETWEEN THE INFLUENCES OF THE SOUTHERN PLAINS LOW AND HIGH
PRESSURE OVER SOUTHERN MANITOBA CANADA WITH EAST WINDS AND MOSTLY
CLOUDY CONDITIONS RESULTING. TEMPERATURES THIS AFTERNOON RANGED FROM
THE TEENS ACROSS NORTH CENTRAL WI...TO THE LOWER AND MIDDLE 20S
ELSEWHERE.
WILL BE WATCHING THE SOUTHERN PLAINS AND NORTHERN PLAINS TROUGHS
CONVERGE ON THE AREA LATE TONIGHT INTO SATURDAY. NOT PARTICULARLY
STRONG DYNAMICS ASSOCIATED WITH THESE WAVES. HOWEVER...THE AREA WILL
BE IN LONG-LIVED RIGHT ENTRANCE REGION OF 300MB JET WHILE THERE IS
SOME WEAK ISENTROPIC UPGLIDE NOTED ON THE NAM 275K SURFACE.
ALSO...THERE IS A DECENT PASSING LOBE OF 700-300 PV-ADVECTION FROM
ABOUT 12Z-18Z SATURDAY. ALL THIS IS EXPECTED TO COME TOGETHER TO
PRODUCE A FAIRLY WIDESPREAD AREA OF LIGHT SNOW WITH THE PEAK
CENTERED FROM ABOUT 09Z-15Z...THEN TAPERING OFF IN THE
AFTERNOON/SATURDAY EVENING AS THE TROUGH AXIS PASSES AND SUBSIDENCE
TAKES OVER. SOME VERY LIGHT SNOW/FLURRIES WILL BE POSSIBLE THROUGH
MIDNIGHT SATURDAY NIGHT BEFORE FULL SUBSIDENCE KICKS IN...DRYING
THINGS OUT. APPEARS AT THIS TIME THERE IS THE POTENTIAL FOR 1/2 UP
TO 2 INCHES OF SNOWFALL OUT OF THIS FROM TONIGHT THROUGH SATURDAY
EVENING. TEMPERATURE-WISE... LOOK FOR LOWS TONIGHT IN THE SINGLE
DIGITS AND TEENS...HIGHS ON SATURDAY IN THE UPPER TEENS TO MIDDLE
20S...AND LOWS SATURDAY NIGHT DROPPING INTO THE SINGLE DIGITS ABOVE
AND BELOW ZERO.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 205 PM CST FRI DEC 13 2013
SUNDAY LOOKS DRY AT THIS TIME BUT CLOUDS WILL BE THICKENING ONCE
AGAIN IN ADVANCE OF THE NEXT MID-LEVEL SHORTWAVE TO IMPACT THE AREA.
FOR SUNDAY NIGHT INTO MONDAY...WARM AIR ADVECTION WING OF THIS WAVE
MOVES IN WITH A GOOD CHANCE FOR LIGHT SNOW TO OVERSPREAD THE AREA.
WILL HAVE TO WATCH CLOSELY AS MODEL BUFKIT SOUNDINGS HINT AT THE
POTENTIAL FOR SOME LOSS OF ICE IN THE COLUMN. THIS COULD LEAD TO
SOME FREEZING DRIZZLE ISSUES. KEPT PRECIPITATION AS ALL SNOW FOR NOW
AFTER COORDINATION/COLLABORATION WITH OTHER OFFICES...BUT WILL
REMAIN LEARY AND KEEP A CLOSE EYE ON LATER MODEL RUNS FOR FREEZING
DRIZZLE POTENTIAL. OTHERWISE...SNOWFALL LOOKS TO BE VERY LIGHT WITH
LESS THAN AN INCH EXPECTED.
TUESDAY THROUGH WEDNESDAY LOOK TO BE DRY FOR NOW AS NORTHWEST FLOW
ALOFT PERSISTS ACROSS THE EASTERN HALF OF THE CONUS.
ECMWF/GFS COMING INTO BETTER AGREEMENT WITH THE LOW PRESSURE SYSTEM
AFFECTING THE AREA ON THURSDAY. APPEARS THERE WILL BE ENOUGH WARM
AIR DRAWN IN WITH THIS SYSTEM TO PRODUCE A RAIN/SNOW MIX FOR
PORTIONS OF THE AREA AS TEMPERATURES WARM INTO THE LOWER/MIDDLE 30S
ALONG AND SOUTH OF I-90. LOOK FOR THE PRECIPITATION TO SWITCH BACK
TO ALL SNOW AS COLD AIR SWEEPS IN BEHIND THE DEPARTING LOW THURSDAY
NIGHT.
THERE WILL BE A LINGERING CHANCE FOR LIGHT SNOW ON FRIDAY AS A
POTENT/COLD MID-LEVEL TROUGH MOVES TOWARD THE UPPER MISSISSIPPI
RIVER FROM THE NORTHERN PLAINS. OTHERWISE...MUCH COLDER TEMPERATURES
LOOK TO INVADE THE AREA WITH HIGHS DROPPING BACK INTO THE TEENS/20S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1123 PM CST FRI DEC 13 2013
THE BAND OF MVFR CLOUDS MOVED BACK OVER BOTH TAF SITES AS EXPECTED
THIS EVENING AND NOW LOOKS LIKE IT WILL REMAIN THROUGH THE PERIOD.
THE THREAT FOR SOME SNOW WILL COME FROM THE SHORT WAVE TROUGH
APPROACHING FROM THE WEST. LIGHT SNOW IS FALLING AHEAD OF THIS
WAVE FROM WESTERN MINNESOTA INTO WISCONSIN WEST OF THE TWIN
CITIES. AS THE WAVE CONTINUES TO MOVE EAST...LOOK FOR THE LIGHT
SNOW TO SLOWLY MOVE SOUTHEAST AND SPREAD OVER THE TAF SITES DURING
THE OVERNIGHT HOURS. CONDITIONS ARE QUITE VARIABLE WITH THE
SNOW...BUT ARE PRIMARILY MVFR WITH SOME LOCATIONS REPORTING IFR
CONDITIONS. THIS CORRESPONDS WELL TO THE 14.00Z NAM AND 14.03Z RAP
BUFKIT SOUNDINGS FOR BOTH SITES AND WILL SHOW PREVAILING MVFR
CONDITIONS IN THE LIGHT SNOW WITH A PERIOD OF IFR POSSIBLE LATE
TONIGHT INTO EARLY SATURDAY MORNING. ONCE THE FORCING FROM THE
MAIN WAVE MOVES PAST...THE NAM SUGGEST SOME WEAK FRONTOGENESIS
IN THE 1000-850 MB LAYER WILL LINGER OVER EASTERN MINNESOTA INTO
THE DAY AS THE NEXT NORTHERN STREAM SHORT WAVE TROUGH MOVES ACROSS
THE REGION. WILL THUS KEEP A MVFR VISIBILITY INTO THE AFTERNOON
BEFORE GOING TO FLURRIES AS THE FRONTOGENESIS WEAKENS BY MID
AFTERNOON.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...04
AREA FORECAST DISCUSSION
NWS PADUCAH KY
128 AM CST Mon Dec 16 2013
.UPDATE...
ISSUED AT 1141 PM CST SUN DEC 15 2013
Updated aviation section for 06z TAF package.
&&
.SHORT TERM...(This Evening through Tuesday Night)
ISSUED AT 213 PM CST SUN DEC 15 2013
The short term forecast will continue to be a sky and temperature
challenge, as no measureable precipitation is forecast with
northwest flow aloft continuing.
Plenty of remnant low level moisture has resulted in a prolonged
period of cloudy skies early today. However, by mid morning,
progress was being made in clearing skies in parts of southeast MO.
The RAP model seemed to be doing the best with regards to the low
level moisture departing that area. It indicates that the clearing
will continue across southeast MO and maybe a bit further east into
southwest IL/KY However, upstream cloudiness from disturbances aloft
will likely keep most of southern IL, southwest IN and a good chunk
of western KY in the clouds through tonight into Monday.
Weak warm air advection will start up in southeast MO later today
and into tonight. As this weak warm advection develops over top a
cold moist snow covered ground, we could be looking at fog
potential, as noted by the previous shift. Fog will be most
prevalent in areas where the clouds have cleared and stay clear.
Therefore, we expect the greatest fog potential in southeast MO. It
will be tricky though because there is quite a bit of low level
moisture upstream yet to travel down this way so pinpointing what
areas might stay partly cloudy vs cloudy will be difficult,
especially when mid clouds are expected later tonight as well.
Interestingly enough, the 12Z SREF indicates the best chance for fog
development, especially after 06Z tonight, in SEMO/far southwest IL.
However, numerical guidance is not as hot on the idea. Will opt for
patchy fog wording in SEMO for now and let the evening shift adjust
as need be.
Although no precipitation is forecast for tonight, weak disturbances
in the flow are going to bring some mid level moisture. Northern
neighboring WFOs have flurries/light snow forecast for tonight.
Looking at soundings/mid level moisture plots in our area, there does
appear to be enough moisture aloft (especially around 06Z)to produce
snowflakes but the atmosphere is very dry below 750mb. But in our
extreme northern counties, the 18Z NAM indicates there just might be
enough moisture and we could wet bulb enough to produce a few
flurries up north of the I-64 corridor but most of the activity
should stay to our north, where the better moisture will be.
Monday through Tuesday, below normal temperatures will persist as
the region remains in northwest flow aloft on the back side of a
longwave trough over the east. Minor disturbances traveling through
this NW flow will likely bring us intermittent clouds but no
precipitation is currently forecast...with the cloudiest areas
being southern IL, southwest IN and parts of west KY. Finally, we
start to get rid of this low level moisture Monday night into
Tuesday across a good part of the area. We will also see robust warm
air advection take place Tuesday night, which will start our big
warm up.
.LONG TERM...(Wednesday Night through Sunday)
ISSUED AT 119 AM CST MON DEC 16 2013
We start the long term portion of the forecast with subtle shifts
in the pattern that will lead to a moderation in temps. The upper
level flow will be backing, as height falls in the southern Plains
occur in response to a digging upper level jet. Downstream ridging
will work in as upper level southwesterlies aid the moderation
process.
By Thursday, this moderating trend includes moisture, and
elevated/overrunning pops begin to appear from the north and west,
as a front will be taking shape and approach from that direction.
Thursday night-Friday, we see surface dew point temps surging
through the 50s, with 60F not far off. 850 mb winds have increased
to 50 kts. Elevated instability parameters such as the K index
suggest at least an isolated mention of thunder is still possible.
Beyond Friday is where the model divergence takes place. However,
despite the differing solutions, a trend of warmer layer threshold
temps is starting to appear, as both the ECMWF/GFS have trended
this direction the last two forecast nights. The ECMWF keeps a
wetter forecast as the boundary still sets up/hangs in the vcnty
thru the weekend, while the GFS moves it on thru before
stalling/returning it. Both suggest mainly liquid pcpn chances by
and large as a whole, although both also support a changeover
before ending mention by late day 7 into day 8.
&&
.AVIATION...
ISSUED AT 119 AM CST MON DEC 16 2013
Lingering IFR cigs at KEVV/KOWB should move out soon. Broken mid
level clouds are expected otherwise with occasional MVFR vsbys possible.
After 14z, VFR conditions are expected through the day. Winds will
be south to southwest at 5 to 10 kts through the TAF period.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1141 PM CST Sun Dec 15 2013
.UPDATE...
ISSUED AT 1141 PM CST SUN DEC 15 2013
Updated aviation section for 06z TAF package.
&&
.SHORT TERM...(This Evening through Tuesday Night)
ISSUED AT 213 PM CST SUN DEC 15 2013
The short term forecast will continue to be a sky and temperature
challenge, as no measureable precipitation is forecast with
northwest flow aloft continuing.
Plenty of remnant low level moisture has resulted in a prolonged
period of cloudy skies early today. However, by mid morning,
progress was being made in clearing skies in parts of southeast MO.
The RAP model seemed to be doing the best with regards to the low
level moisture departing that area. It indicates that the clearing
will continue across southeast MO and maybe a bit further east into
southwest IL/KY However, upstream cloudiness from disturbances aloft
will likely keep most of southern IL, southwest IN and a good chunk
of western KY in the clouds through tonight into Monday.
Weak warm air advection will start up in southeast MO later today
and into tonight. As this weak warm advection develops over top a
cold moist snow covered ground, we could be looking at fog
potential, as noted by the previous shift. Fog will be most
prevalent in areas where the clouds have cleared and stay clear.
Therefore, we expect the greatest fog potential in southeast MO. It
will be tricky though because there is quite a bit of low level
moisture upstream yet to travel down this way so pinpointing what
areas might stay partly cloudy vs cloudy will be difficult,
especially when mid clouds are expected later tonight as well.
Interestingly enough, the 12Z SREF indicates the best chance for fog
development, especially after 06Z tonight, in SEMO/far southwest IL.
However, numerical guidance is not as hot on the idea. Will opt for
patchy fog wording in SEMO for now and let the evening shift adjust
as need be.
Although no precipitation is forecast for tonight, weak disturbances
in the flow are going to bring some mid level moisture. Northern
neighboring WFOs have flurries/light snow forecast for tonight.
Looking at soundings/mid level moisture plots in our area, there does
appear to be enough moisture aloft (especially around 06Z)to produce
snowflakes but the atmosphere is very dry below 750mb. But in our
extreme northern counties, the 18Z NAM indicates there just might be
enough moisture and we could wet bulb enough to produce a few
flurries up north of the I-64 corridor but most of the activity
should stay to our north, where the better moisture will be.
Monday through Tuesday, below normal temperatures will persist as
the region remains in northwest flow aloft on the back side of a
longwave trough over the east. Minor disturbances traveling through
this NW flow will likely bring us intermittent clouds but no
precipitation is currently forecast...with the cloudiest areas
being southern IL, southwest IN and parts of west KY. Finally, we
start to get rid of this low level moisture Monday night into
Tuesday across a good part of the area. We will also see robust warm
air advection take place Tuesday night, which will start our big
warm up.
.LONG TERM...(Wednesday through Sunday)
ISSUED AT 213 PM CST SUN DEC 15 2013
Will continue the forecast for an active weather regime late this
week possibly extending into the weekend.
Surface high pressure`s dominance on our FA will quickly fade as the
high moves east toward the south Atlantic Coast by Wednesday
evening. This will set the stage for southerly winds and a
pronounced warm up Wednesday with the FA remaining in the warm
sector until a cold front moves across the FA Friday. Both the ECMWF
and GFS now bring this front through the FA Friday with the ECMWF
now even a bit faster than the GFS. Will maintain small POPS across
the west/NW part of the FA for Thursday and increase POPS slightly
for Thursday night and Friday given the fairly consistent signal
with the synoptic pattern through Friday. Will also keep a chance of
thunderstorms for Thu night and Fri with K indices consistently AOA
30 for the last several model runs.
Confidence with the post frontal part of the forecast remains more
uncertain given major model changes with the GFS in particular. This
is due to forecasting the movement of the southwest U.S. upper
low/trough which is much slower with the latest GFS run and
therefore the significant change/lesser precip chances for the
weekend as a result of the southeast progression of the surface cold
front and subsequent post frontal drying. Will tend to lean more
toward the ECMWF position of maintaining... including with the 12Z
model run...ample moisture across our FA given its NE progression of
the upper low.
Precip type will once again be borderline with the often
generalization of the N part of the FA having the best chance for
wintry precip and areas near the MO/AR and KY/TN border having a
greater likelihood of rain as supported by a blend of several
thickness parameters. This is particularly valid of the late weekend
precip ahead of the upper low...assuming this even materializes
given the aforementioned model differences.
Warm air advection will occur Wed-Fri until the cold front moves
through the FA Friday. The trend has been even warmer temps for
Thursday which is now forecast to be as warm as Friday with the
exception of the southeast/Pennyrile area where a later passage of
the cold front should result in Friday temps AOA 60. Back to more
typical temps thereafter.
&&
.AVIATION...
ISSUED AT 1141 PM CST SUN DEC 15 2013
Lingering IFR cigs at KEVV/KOWB will move out by 08z. Broken mid
level clouds are expected overnight with occasional MVFR vsbys
possible. After 14z, VFR conditions are expected through the day.
Winds will be south to southwest at 5 to 10 kts through the TAF
period.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
AVIATION...RST
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
324 AM CST Mon Dec 16 2013
.SHORT TERM: (Through Tonight)
Issued at 1233 AM CST Mon Dec 16 2013
Clipper continues to move esewd thru the region with the sfc fnt
stretched thru the area near I-70. A lot of uncertainty remains as
to where any fg develops, if any, or if mainly st will develop.
Areas S of the fnt may continue to see enuf mixing to prevent any
fg development despite the additional moisture due to sn melt.
Clouds are expected to linger thru much of the day across the nrn
half of the CWA.
Have trended twd the warmer guidance across the region. May still
need to raise temps across the srn counties as some areas further
SW have already reached the lower to mid 40s.
With mixing expected to continue overnight and at least high
clouds spreading over the region, have trended twd the warmer
guidance thru tonight as well.
Tilly
.LONG TERM: (Tuesday through Sunday)
Issued at 242 AM CST Mon Dec 16 2013
(Tuesday through Wednesday)
With no precip expected thru this period, focus will be warming
temps. Mdls are in good agreement regarding mass fields. Prev
forecast still appears to be largely on track and have therefore
made only minor changes. In general, continued trend twd warmer
guidance. With strong WAA over the region on Wed, going forecast
may not be warm enuf as thermal ridge pushes thru the region.
Believe mdls are holding on to the snow field too long into the
forecast period. One factor that may hinder this strong warming is
development of fg/st.
(Thursday through Sunday)
Focus quickly turns to the systems to impact the area late this
week and thru the weekend.
Mdls are coming into better agreement, but differences remain that
would be the difference in ra turning to sn or resulting in fzra.
Timing and placement differences exist over the weekend as another
system pulls newd thru the region. The ECMWF brings the sfc low
further nwd suggesting ra, while the GFS keeps the system further S
suggesting mostly a sn event. Due to uncertainty regarding
placement and timing, have kept the going forecast as is except
for changes in POPs to account for at least an agreement or
possibility of precip. Will make adjustments as needed as mdls
come into better agreement.
Tilly
&&
.AVIATION: (For the 06z TAFs through 06z Monday Night)
Issued at 1138 PM CST Sun Dec 15 2013
BUFKIT soundings from the RAP still show light winds and a strong
surface-based inversion along with nearly saturated conditions at
the lowest levels. It still looks like a period of IFR to MVFR fog
will develop over the next 6 hours, then lift into stratus during
the morning hours, but confidence remains low with respect to the
timing. Stratus is likely to linger for most of the day due to
poor mixing and low sun angle, especially at KUIN. Conditions
should improve during the day, but fog/stratus is possible again
on Monday night due to the additional moisture provided by melting
snow.
Specifics for KSTL: A boundary is wavering back and forth across
KSTL, causing fluctuations in the temperature and dew point, which
in turn is affecting the fog potential. It still looks like a
period of IFR or MVFR fog will develop over the next 6 hours, then
lift into stratus during the morning hours. Confidence in the
timing of fog remains low. Conditions should improve during the
day, however fog/stratus is possible again on Monday night due to
the additional moisture provided by melting snow.
Kanofsky
&&
.PRELIMINARY POINT TEMPS/POPS:
Saint Louis 42 28 45 29 / 5 0 0 0
Quincy 32 22 38 22 / 5 0 0 0
Columbia 45 27 46 28 / 5 0 0 0
Jefferson City 46 27 48 28 / 5 0 0 0
Salem 40 27 41 26 / 10 0 0 0
Farmington 47 28 48 28 / 5 0 0 0
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
109 AM CST Mon Dec 16 2013
.SHORT TERM: (Through Tonight)
Issued at 1233 AM CST Mon Dec 16 2013
Clipper continues to move esewd thru the region with the sfc fnt
stretched thru the area near I-70. A lot of uncertainty remains as
to where any fg develops, if any, or if mainly st will develop.
Areas S of the fnt may continue to see enuf mixing to prevent any
fg development despite the additional moisture due to sn melt.
Clouds are expected to linger thru much of the day across the nrn
half of the CWA.
Have trended twd the warmer guidance across the region. May still
need to raise temps across the srn counties as some areas further
SW have already reached the lower to mid 40s.
With mixing expected to continue overnight and at least high
clouds spreading over the region, have trended twd the warmer
guidance thru tonight as well.
Tilly
.LONG TERM: (Monday Night through Next Sunday)
Issued at 259 PM CST Sun Dec 15 2013
Despite another weak and ill-defined cold front passing though the
area on Tuesday, the temperatures should moderate some. The real
moderation however will begin to unfold on Tuesday night as the
surface high retreats and low level WAA gets underway. Strong WAA
will be in full swing on Wednesday as low level flow becomes
south/southwesterly and the upper flow transitions to quasi-zonal.
This should be a big snow melter with highs in the upper 40s-middle
50s.
The extended portion of the forecast, especially towards the
weekend, is marked by considerable uncertainty. A big pattern change
will continue to evolve with considerable amplification from the
central Pacific across the CONUS. The main feature will be the
development of a split flow regime with a deep long wave positively
tilted trof in the western U.S. and upper low in the southwest. This trof
develops in response to the absorption of an upper low currently in
the southeast Pacific near 27N/134W and short waves digging
southward out of the Gulf of AK along the west coast. The northern
stream will serve to bring a cold front through the area Thursday
night/early Friday accompanied by a chance of rain and possibly some
rain/snow mix in the wake. However the northern stream is sharper on
the GFS and it also leaves the upper low spinning in the vicinity of
northern Baja CA. This solution would suggest limited post-frontal
precipitation with high pressure building into the Mid MS Valley
late Friday and then additional waves in the northern stream
reinforcing the high pressure and essentially keeping precipitation
south of the area. Alternatively the ECMWF develops an overrunning
scenario Saturday into Sunday and potential for a winter mess.
There is no scientific basis at this point in time to suggest one
solution is vastly better than another and the models will continue
to change multiple times in the details in the coming week. Given
the forecast large scale pattern changes and vastly differing model
solutions and resultant low confidence, the best approach at this
time is more of an ensemblistic approach with some mixed flavor.
Glass
&&
.AVIATION: (For the 06z TAFs through 06z Monday Night)
Issued at 1138 PM CST Sun Dec 15 2013
BUFKIT soundings from the RAP still show light winds and a strong
surface-based inversion along with nearly saturated conditions at
the lowest levels. It still looks like a period of IFR to MVFR fog
will develop over the next 6 hours, then lift into stratus during
the morning hours, but confidence remains low with respect to the
timing. Stratus is likely to linger for most of the day due to
poor mixing and low sun angle, especially at KUIN. Conditions
should improve during the day, but fog/stratus is possible again
on Monday night due to the additional moisture provided by melting
snow.
Specifics for KSTL: A boundary is wavering back and forth across
KSTL, causing fluctuations in the temperature and dew point, which
in turn is affecting the fog potential. It still looks like a
period of IFR or MVFR fog will develop over the next 6 hours, then
lift into stratus during the morning hours. Confidence in the
timing of fog remains low. Conditions should improve during the
day, however fog/stratus is possible again on Monday night due to
the additional moisture provided by melting snow.
Kanofsky
&&
.PRELIMINARY POINT TEMPS/POPS:
Saint Louis 28 44 28 54 / 0 0 0 0
Quincy 22 37 21 48 / 0 0 0 0
Columbia 27 45 27 56 / 0 0 0 0
Jefferson City 27 47 27 57 / 0 0 0 0
Salem 27 40 25 48 / 0 0 0 0
Farmington 28 47 27 52 / 0 0 0 0
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1159 PM CST Sun Dec 15 2013
.UPDATE:
Issued at 849 PM CST Sun Dec 15 2013
A well-defined baroclinic zone reaching from the Dakotas
southeastward through northwest Missouri has extended through east
central Missouri and into southwest Illinois this evening, and
makes for a bit of a tricky forecast overnight tonight. Despite
uncertainties associated with this baroclinic zone, feel that
overall, the going forecast this evening remains on track.
Pockets of light snow have continued over Iowa and Illinois in
response to a vort max moving within the northwest flow aloft, and
while much of the activity looks to remain north of the area,
still cannot rule out some light freezing rain or light snow,
mainly over the northern periphery of the forecast area. The most
recent run of the HRRR supports this, indicating spotty
precipitation over the next few hours over northeast Missouri and
west central Illinois. Near and south of the baroclinic zone,
dewpoints this evening are still hanging in the middle to upper
20s, thus feel that the mention of fog for this area continues to
be warranted tonight as temperatures fall. Beyond adjusting near
term trends based on current observations, no major changes have
been warranted this evening.
JP
&&
.SHORT TERM: (Tonight through Monday)
Issued at 259 PM CST Sun Dec 15 2013
Lots of caveats to the forecast for tonight leading to low confidence
in some of the details. A strong surface front currently extends
from western SD through central NE and northeast KS across northern
MO into west central IL. The models are in decent agreement that a
surface low pressure wave will track southeastward along the front
from the central Plains into southern IL tonight with the front
sagging southward in its wake. This surface low will be in response
to a weak elongated short wave/vort max migrating southeastward
within the NW flow aloft. The large scale forcing and strongest
low level baroclinicity/frontogenesis will reside to the north of
the forecast area from Iowa thru north central IL into southeast
IN and this is where the greatest threat of snow should reside.
Along the far southern periphery of this zone which encompasses a
zone from around Edina to Quincy to White Hall to Nokomis, the RAP
suggests there could be a brief shot of decent ascent. It also has
some very light QPF within this zone and the last few available
runs of the HRRR showed some spotty precipitation. The overall low
level flow regime is characterized south of the aforementioned
front and above the boundary layer by warm air advection. This WAA
while also contributing to lift has warmed the atmosphere and
soundings suggest any precipitation could teeter between light
freezing rain or light snow. I have added some low pops to account
for this probability and it will bear close watching on the
evening shift. Further south snow melt has contributed to low
level moistening and some of the guidance suggests fog and stratus
will develop. The 12z run of the NAM even went as far as developing
freezing drizzle. The boundary layer is where all the models have
the poorest time resolving, thus my confidence is limited, but
given the current surface dew points are now close to the forecast
mins I have opted to included a mention of fog in the forecast. If
stratus and fog are widespread on Monday morning, then the trend
should be for this to erode/dissipate as the morning progresses
and weak low level WAA kicks in. If the stratus/fog or clouds are
at a minimum then my forecast highs are likely too cool.
Glass
.LONG TERM: (Monday Night through Next Sunday)
Issued at 259 PM CST Sun Dec 15 2013
Despite another weak and ill-defined cold front passing though the
area on Tuesday, the temperatures should moderate some. The real
moderation however will begin to unfold on Tuesday night as the
surface high retreats and low level WAA gets underway. Strong WAA
will be in full swing on Wednesday as low level flow becomes
south/southwesterly and the upper flow transitions to quasi-zonal.
This should be a big snow melter with highs in the upper 40s-middle
50s.
The extended portion of the forecast, especially towards the
weekend, is marked by considerable uncertainty. A big pattern change
will continue to evolve with considerable amplification from the
central Pacific across the CONUS. The main feature will be the
development of a split flow regime with a deep long wave positively
tilted trof in the western U.S. and upper low in the southwest. This trof
develops in response to the absorption of an upper low currently in
the southeast Pacific near 27N/134W and short waves digging
southward out of the Gulf of AK along the west coast. The northern
stream will serve to bring a cold front through the area Thursday
night/early Friday accompanied by a chance of rain and possibly some
rain/snow mix in the wake. However the northern stream is sharper on
the GFS and it also leaves the upper low spinning in the vicinity of
northern Baja CA. This solution would suggest limited post-frontal
precipitation with high pressure building into the Mid MS Valley
late Friday and then additional waves in the northern stream
reinforcing the high pressure and essentially keeping precipitation
south of the area. Alternatively the ECMWF develops an overrunning
scenario Saturday into Sunday and potential for a winter mess.
There is no scientific basis at this point in time to suggest one
solution is vastly better than another and the models will continue
to change multiple times in the details in the coming week. Given
the forecast large scale pattern changes and vastly differing model
solutions and resultant low confidence, the best approach at this
time is more of an ensemblistic approach with some mixed flavor.
Glass
&&
.AVIATION: (For the 06z TAFs through 06z Monday Night)
Issued at 1138 PM CST Sun Dec 15 2013
BUFKIT soundings from the RAP still show light winds and a strong
surface-based inversion along with nearly saturated conditions at
the lowest levels. It still looks like a period of IFR to MVFR fog
will develop over the next 6 hours, then lift into stratus during
the morning hours, but confidence remains low with respect to the
timing. Stratus is likely to linger for most of the day due to
poor mixing and low sun angle, especially at KUIN. Conditions
should improve during the day, but fog/stratus is possible again
on Monday night due to the additional moisture provided by melting
snow.
Specifics for KSTL: A boundary is wavering back and forth across
KSTL, causing fluctuations in the temperature and dew point, which
in turn is affecting the fog potential. It still looks like a
period of IFR or MVFR fog will develop over the next 6 hours, then
lift into stratus during the morning hours. Confidence in the
timing of fog remains low. Conditions should improve during the
day, however fog/stratus is possible again on Monday night due to
the additional moisture provided by melting snow.
Kanofsky
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
357 AM CST MON DEC 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CST MON DEC 16 2013
TODAY AND TONIGHT...A POWERFUL THERMAL RIDGE WILL CONTINUE OPERATING
ACROSS THE FORECAST AREA. A WEAK COLD FRONT ACROSS SERN MT THIS
MORNING COULD DROP THROUGH THE NERN PORTION OF THE FCST AREA THIS
AFTERNOON BUT TEMPS BEHIND THE FRONT ARE ABOVE FREEZING SO NO
SIGNIFICANT COOLING IS EXPECTED. THE TEMPERATURE FCST TODAY FOLLOWS
THE WARMEST MODELS WHICH ARE THE HRRR AND RAP FORECASTING MID TO
UPPER 50S ACROSS SWRN NEB. THESE MODELS HAVE VERIFIED THE BEST OVER
THE WEEKEND. 40S ARE EXPECTED ACROSS THE SNOW COVER NORTH AND THIS
SNOW IS MELTING.
WINDS AT H850 MB CONTINUE AT 30 TO 40 KT TODAY WITH 500M AGL WINDS
OF 20 TO 25 KTS. THIS WOULD PRODUCE 15 TO 25 MPH WINDS AT THE SFC.
THE MID LEVEL CLOUD SHIELD ACROSS WRN SD AND ERN MT IS EXPECTED TO
SLICE THROUGH THE NERN PORTION OF THE FCST AREA TODAY WITH SCT-BKN
CIRRUS SOUTH AND WEST.
HIGH CLOUDS ARE EXPECTED TONIGHT AND THE NAM SUGGESTED MID LEVEL
CLOUDS NORTH AND EAST. ALL OF THESE CLOUDS SHOULD LIMIT RADIATIONAL
COOLING AND THE BEST GUESS WITH LOWS TONIGHT IS 20S WITH UPPER 20S
UNDER THE MID LEVEL CLOUD DECK. H850 MB WINDS WEAKEN TO 10 TO 25 KTS
WEST WHICH WOULD SUPPORT MODEST RADIATIONAL COOLING DESPITE THE
CLOUD COVER. 30 TO 40KT H850 WINDS CONTINUE NORTH AND EAST
SUPPORTING THE WARMER LOWS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 356 AM CST MON DEC 16 2013
PRIMARY FORECAST CONCERNS DEAL WITH TEMPERATURES THE NEXT SEVERAL
DAYS...THEN TURNS TO STRONG FRONTAL PASSAGE THURSDAY WITH COLDER
TEMPERATURES AND POSSIBLY SNOW FOR PARTS OF THE AREA.
RIDGING ALOFT WILL BUILD OVER THE CENTRAL PLAINS ON TUESDAY IN THE
WAKE OF AN UPPER LEVEL SHORTWAVE TROUGH. STILL EXPECT TO SEE AN
INFLUENCE ON TEMPERATURES OVER THE NORTHERN PARTS OF NEBRASKA FROM
THE SNOWPACK...HOWEVER WITH TEMPERATURES RISING ABOVE FREEZING
SHOULD CONTINUE TO SEE THE SNOW MELT IN THE COMING DAYS. DO HAVE A
WARMING TREND FOR THE SNOWPACK LOCATIONS...HOWEVER DIDN/T GO TOO
WARM YET UNTIL START TO SEE MUCH LESS INFLUENCE FROM THE SNOW. WHERE
THE GROUND IS DRY...LOOKING AT HIGHS 10 TO 15 DEGREES WARMER IN THE
50S TO NEAR 60 ON TUESDAY.
THE UPPER LEVEL LOW CURRENTLY OVER ALASKA...AS WELL AS THE UPPER LOW
OFF THE CALIFORNIA COAST WILL BOTH MAKE THEIR WAY ONTO THE WEST
COAST TUESDAY NIGHT AND WEDNESDAY. THESE TWO SYSTEMS WILL STAY
SEPARATE...BUT WILL BOTH WORK TO DEEPEN THE TROUGH ACROSS THE
WESTERN CONUS. AS THIS OCCURS...THE THERMAL RIDGE WILL STRENGTHEN
WITH 850MB TEMPERATURES NEARING 16C. DID INCREASE LOWS FOR TUESDAY
NIGHT DUE TO THE WARMING EXPECTED...HOWEVER WITH FAIRLY LIGHT WINDS
AND DEWPOINTS IN THE UPPER TEENS AND LOW 20S...MAY STILL GET
TEMPERATURES TO FALL INTO THE MID AND UPPER 20S. THIS PERIOD MAY
NEED TO BE ADJUSTED IN COMING FORECASTS. THEN FOR WEDNESDAY...SOME
PORTIONS OF SOUTHWEST NEBRASKA SHOULD APPROACH OR EXCEED 60 DEGREES.
AGAIN...AREAS ACROSS THE NORTH ARE QUESTIONABLE DUE TO THE SNOWPACK.
WILL SEE HOW THE NEXT COUPLE OF DAYS MELT THE SNOW AND WILL ADJUST
HIGHS IN THESE AREAS AS NEEDED. WINDS LOOK TO BE PRETTY LIGHT ON
WEDNESDAY TO LIMIT THE MIXING WITH MODELS ONLY MIXING TO 850MB OR
LOWER. IF DEEPER MIXING CAN BE REALIZED TEMPERATURES WILL BE TOO LOW
AND NEED TO BE ADJUSTED UPWARDS. FOR EXAMPLE...AT LBF MIXING TO
850MB WEDNESDAY AFTERNOON WOULD BRING A HIGH OF 64 DEGREES.
IS SOME DIFFERENCES ON TIMING OF THE ARCTIC FRONT ON
THURSDAY...WHICH THEN TRANSLATES TO LOWER CONFIDENCE ON HIGHS.
LOOKING AT THE 16.00Z MODELS...THE OPERATIONAL GFS HAS STAYED FAIRLY
SIMILAR IN TIMING WHICH IS THE COLDEST SOLUTION. THIS WOULD SUGGEST
HIGHS FROM THE UPPER TEENS OVER NORTH CENTRAL NEBRASKA TO THE MID
30S IN THE SOUTHWEST. HOWEVER THE GFS ENSEMBLES ARE SHOWING A
VARIETY OF SOLUTIONS AS IT SHOWS A DIFFERENCE OF 5 STANDARD
DEVIATIONS FOR MUCH OF THE FORECAST WHICH TRANSLATES TO A 20 DEGREE
DIFFERENCE AMONG JUST THE GFS SOLUTIONS. THE ECMWF DID SPEED THE
FRONT UP SLIGHTLY WITH THE 16.00Z RUN...HOWEVER THE GEM SLOWED IT
DOWN. WITH THE WIDE VARIETY OF SOLUTIONS AND LOWER CONFIDENCE WILL
KEEP THE FORECAST FAIRLY SIMILAR TO THE ONGOING FORECAST UNTIL THERE
IS BETTER SUPPORT TO GO COLDER.
IT DOES CONTINUE TO LOOK LIKE THERE WILL BE SOME POST-FRONTAL
PRECIPITATION...HOWEVER IT LOOKS LIKE VERY LIGHT PRECIPITATION. IN
THE UPPER LEVEL PATTERN...THE UPPER LOW NOW OFF THE CALIFORNIA COAST
WILL MOVE ACROSS THE CENTRAL PLAINS JUST AHEAD OF THE ARCTIC FRONT
/WITH LITTLE OR NO IMPACT IN THE SENSIBLE WEATHER/...AND WITH THE
WEST COAST SYSTEM DIGGING INTO SOUTHERN CALIFORNIA ON
THURSDAY...THERE ISN/T A GOOD MOISTURE FEED INTO THE AREA AS THE
ARCTIC FRONT PASSES. THIS WILL LEAD TO A DISJOINTED ATTEMPT AT
PRECIPITATION AS LIFT IS NOT IN THE AREA WHEN THE COLUMN SEES THE
GREATEST AMOUNT OF MOISTURE...WHILE THE MODELS ARE ALSO SHOWING A
DRY LAYER AROUND 700MB TO ALSO INHIBIT PRECIPITATION. CURRENT
FORECAST LIMITS THE PRECIPITATION TO MAINLY THE NORTHWEST HALF OF
THE FORECAST AREA. HAVE BEEN WATCHING A SIGNAL FOR DRIZZLE ON
THURSDAY OVER THE PAST FEW DAYS...AND ALTHOUGH SOUNDINGS WON/T
DISCOUNT IT RIGHT NOW WITH THE DRY LAYER EXPECTED...THEY ARE ALSO
SHOWING ENOUGH DRY AIR RIGHT AT THE SURFACE WHICH MAY KEEP ANY
DRIZZLE FROM BEING A THREAT. THEN AS THE COLUMN COOLS FURTHER WITH
THE COLD AIR INTRUSION...AND THE DRY LAYER GOES AWAY...DRIZZLE
POTENTIAL WILL DIMINISH WITH ONLY SNOW CHANCES. WILL CONTINUE TO
KEEP THE DRIZZLE MENTION OUT OF THE FORECAST FOR NOW AND WATCH IN
THE COMING DAYS.
BEYOND THURSDAY NIGHT THE MODELS ARE TRYING TO KICK OUT THE COLD AIR
TO BRING MORE SEASONABLE TEMPERATURES TO THE FORECAST AREA INTO NEXT
WEEKEND. HOWEVER...THE GFS ENSEMBLE MEMBERS ARE ALL OVER THE BOARD
WITH STANDARD DEVIATIONS OF 5 TO 7 ON HIGHS AND LOWS FRIDAY THROUGH
SUNDAY SO CONFIDENCE IS NOT REAL HIGH AT THIS POINT ON TEMPERATURES
THROUGH THAT TIME FRAME AND HAVE USED A CONSENSUS APPROACH FOR THE
FORECAST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1115 PM CST SUN DEC 15 2013
WITH ONLY MIDDLE AND HIGH CLOUD CEILINGS AND NO RESTRICTIONS TO
VISIBILITY...FLIGHT CONDITIONS WILL BE UNRESTRICTED THROUGH MONDAY
EVENING.
WIND 270-300 AT LESS THAN 10KT WILL INCREASE TO 10-14KT BY LATE
MONDAY MORNING OR EARLY AFTERNOON.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...BROOKS
AVIATION...SPRINGER
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1217 AM CST MON DEC 16 2013
.UPDATE...
ISSUED AT 1217 AM CST MON DEC 16 2013
LATEST WATER VAPOR SHOWS THE NEXT UPSTREAM SHORTWAVE NOW SEEN
CIRCULATING INTO SOUTHWEST MANITOBA. REGIONAL RADAR HAS AN AREA OF
LIGHT SNOW SHIFTING ACROSS THE NORTHERN BORDER WILL BE WATCHED
CLOSELY AS THE PREVIOUS FORECAST CAPTURED THE POTENTIAL FOR
FREEZING RAIN AS WARMER AIR CONTINUES TO ADVECT IN FROM THE WEST.
THE HRRR AND RAP13 HAVE AN AREA OF LIGHT SNOW FOLLOWED BY A POCKET
OF LIGHT FREEZING RAIN ON ITS BACKEDGE SPREADING FROM NORTHWEST TO
SOUTHEAST OVERNIGHT. THIS IS ALSO CONFIRMED ON THE NAM HOURLY
BUFKIT SOUNDINGS. THE CURRENT FORECAST HAS THIS HANDLED WELL WITH
LITTLE CHANGES NEEDED AT THIS TIME.
UPDATE ISSUED AT 949 PM CST SUN DEC 15 2013
MAIN UPDATE CONCERN WAS INCREASING WINDS LATE TONIGHT INTO MONDAY
AND POSSIBLY SOME MIXED PRECIPITATION. 16 DEC 00 UTC NAM SOUNDINGS
SHOW QUITE A BIT OF WARM AIR ALOFT LATEST HRRR CONTINUES TO
INDICATE A BAND OF LIGHT PRECIPITATION MOVING NORTHWEST TO
SOUTHEAST ACROSS THE AREA LATE TONIGHT. IF THIS DEVELOPS...NAM
SOUNDINGS INDICATE A POSSIBILITY OF FREEZING RAIN OR SLEET. AS YOU
GET INTO EASTERN PORTIONS OF CENTRAL NORTH DAKOTA IT MAY REMAIN
COLD ENOUGH FOR ALL SNOW. PRECIPITATION SHOULD REMAIN LIGHT SO AT
THIS TIME AM NOT ANTICIPATING ANY ADVISORY. WILL MENTION THE
POSSIBILITY OF MIXED PRECIPITATION IN THE UPDATED HWO. WILL ALSO
MENTION PATCHY BLOWING SNOW...MAINLY NORTH LATE TONIGHT INTO
MONDAY AS WEST WINDS INCREASE BEHIND THE WARM FRONT. UPDATED
PRODUCTS WILL BE SENT OUT SHORTLY.
UPDATE ISSUED AT 658 PM CST SUN DEC 15 2013
WILL NEED TO CONTINUE AND MONITOR TEMPERATURES THROUGH THE
EVENING. WARM FRONT REMAINS OVER WESTERN NORTH DAKOTA AND WILL
LIKELY BE A FEW MORE HOURS BEFORE IT BEGINS TO MAKE PROGRESS
EASTWARD. THUS WILL NEED TO MODIFY EVENING TEMPERATURES WITH
CENTRAL AND EASTERN AREAS STARTING OUT WITH TEMPERATURES MAINLY IN
THE SINGLE DIGITS ABOVE ZERO...WITH THE FAR EAST IN THE SINGLE
DIGITS BELOW ZERO. TEMPERATURES ARE EXPECTED TO RISE OVERNIGHT SO
THESE WILL LIKELY BE THE OVERNIGHT LOWS...UNLESS WE WOULD DROP A
FEW MORE DEGREES BEFORE TEMPERATURES BEGIN TO CLIMB.
LATEST RAP AND ESPECIALLY HRRR SEEM TO HAVE A REASONABLE HANDLE ON
THE CURRENT LIGHT SNOW OVER THE NORTHEAST CWA. UTILIZED THE HRRR
FOR SHORT TERM POPS TONIGHT. THE AREA OVER THE NORTH CENTRAL MOVES
SOUTHEAST WITH ANOTHER AREA OF LIGHT SNOW DEVELOPING OVER THE
NORTHWEST LATER THIS EVENING AND SPREADING SOUTHEAST AS THE WARM
FRONT TRACKS EAST ACROSS THE CWA.
&&
.SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON)
ISSUED AT 319 PM CST SUN DEC 15 2013
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE CHANCES FOR
LIGHT SNOW TONIGHT AND MONDAY...ALONG WITH A WARMING TREND OVER
THE NEXT 24 HOURS FOR MOST LOCATIONS.
CURRENTLY...LIGHT SNOW CONTINUES TO DIMINISH AND PUSH EAST AS
FORCING AHEAD OF A SFC TROUGH DECREASES. SKIES HAVE PARTIALLY
CLEARED WEST CENTRAL AND SOUTHWEST BEHIND THE TROUGH. LEFT EXIT
REGION OF AN UPPER LEVEL JET STREAK WILL REMAIN ALOFT AT LEAST
THROUGH TONIGHT. COUPLED WITH A WEAK MID LEVEL DISTURBANCE WILL
MAINTAIN A SLIGHT CHANCE OF LIGHT SNOW MOST LOCATIONS THROUGH 12Z
ALONG WITH CLOUDY SKIES.
WEAK CAA TONIGHT INTO MONDAY...HOWEVER WITH THE INCREASE IN MIXING
WE EXPECT THE ARCTIC AIR TO BE SCOURED OUT RESULTING IN STEADY TO
WARMING TEMPERATURES TONIGHT INTO MONDAY. HIGHS IN THE 30S WILL BE
COMMON ACROSS WEST AND CENTRAL NORTH DAKOTA MONDAY AFTERNOON.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 319 PM CST SUN DEC 15 2013
THE MAIN FORECAST ISSUE IS THE POTENTIAL FOR ANOTHER ROUND OF SNOW
AND COLDER TEMPERATURES MID TO LATE WEEK.
RELATIVELY MILD AIR WILL OVERSPREAD THE ENTIRE FORECAST AREA ON
MONDAY AND WILL CONTINUE MONDAY NIGHT THROUGH TUESDAY NIGHT. A
REINFORCEMENT OF MILD PACIFIC AIR WILL MOVE INTO THE REGION TUESDAY
NIGHT AS AN ALBERTA CLIPPER LOW PRESSURE SYSTEM MOVES FROM ALBERTA
TUESDAY AFTERNOON TO SOUTHERN MANITOBA BY WEDNESDAY MORNING...WITH A
WARM FRONT EXTENDING FROM THE LOW THAT WILL MOVE EAST ACROSS NORTH
DAKOTA TUESDAY NIGHT.
ON WEDNESDAY AN ARCTIC COLD FRONT IS FORECAST TO ENTER NORTHERN
NORTH DAKOTA LATE MORNING/NOON...AND MOVE SOUTH ACROSS THE STATE
REACHING THE SOUTH DAKOTA BORDER BY/DURING WEDNESDAY EVENING. THUS A
LARGE TEMPERATURE DIFFERENCE FROM NORTH TO SOUTH ACROSS THE STATE ON
WEDNESDAY. TEMPERATURES SHOULD REACH INTO THE TEENS TO LOWER 20S
ALONG AND AHEAD OF THE ARCTIC FRONT IN THE NORTHERN COUNTIES...AND
REACH INTO THE UPPER 20S/MID 30S SOUTHERN COUNTIES.
AS THE SURFACE ARCTIC FRONT MOVES SOUTH...AN UPPER LEVEL TROUGH WILL
DIG SOUTHWARD ACROSS THE ROCKIES/FRONT RANGE...AND THE TROUGH AXIS
AND ACCOMPANYING ENERGY IMPULSE WILL ACT TO INDUCE SNOWFALL ALONG
AND BEHIND THE ARCTIC FRONT. AT THIS TIME THE MODEL SOLUTIONS APPEAR
TO COME CLOSER TO AGREEMENT...WITH SNOWFALL IN MONTANA
WEDNESDAY...EXPANDING EASTWARD INTO NORTH DAKOTA WEDNESDAY NIGHT AND
THURSDAY...AND EXITING THE STATE TO THE EAST THURSDAY NIGHT. CURRENT
MODELS SUGGEST SOUTHERN NORTH DAKOTA AND NORTHERN SOUTH DAKOTA WOULD
BE THE TARGET FOR HIGHEST PRECIPITATION AMOUNTS.
CURRENT ESTIMATES ARE THAT IN A TIME PERIOD OF WEDNESDAY NIGHT
THROUGH THURSDAY NIGHT: 2 TO 3 INCHES OF SNOW ALONG AND SOUTH OF
INTERSTATE 94...TO AROUND 1/2 INCH ALONG THE CANADIAN BORDER.
THE ARCTIC AIR REMAINS IN PLACE THURSDAY THROUGH FRIDAY/FRIDAY
NIGHT. LOW TEMPERATURES BELOW ZERO IN THE NORTH WEDNESDAY
NIGHT...AND OVER ALL OF NORTH DAKOTA THURSDAY NIGHT...AND MOST AREAS
FRIDAY NIGHT. WIND CHILL HEADLINES MAY BE NEEDED THURSDAY NIGHT
THROUGH FRIDAY MORNING. THEN SOME MODERATION OVER THE WEEKEND - BUT
STILL BELOW AVERAGE TEMPERATURES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1217 AM CST MON DEC 16 2013
THROUGH 14Z MONDAY...HAVE INCLUDED A BRIEF PERIOD OF LIGHT SNOW AND
FREEZING RAIN FROM KMOT TO KJMS. USED A VCSH FROM KISN/KBIS/KDIK.
AFTER 14Z MONDAY...BRISK WEST TO NORTHWEST WINDS OF 15 TO 30 MPH
WILL TAKE CONTROL ACROSS WESTERN AND CENTRAL NORTH DAKOTA. EXPECT
MAINLY VFR CIGS AND VSBYS THROUGH THE PERIOD.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...NH
LONG TERM...JV
AVIATION...KS
AREA FORECAST DISCUSSION
NWS PORTLAND OR
925 PM PST SUN DEC 15 2013
.SYNOPSIS...A WEAK STATIONARY FRONT IS DISSIPATING OVER OREGON THIS
EVENING LEAVING PLENTY OF LOW LEVEL MOISTURE BEHIND. THIS MOISTURE
WILL RESULT IN LOCALLY DENSE FOG TONIGHT AND MONDAY MORNING. HIGH
PRESSURE WILL BUILD INTO THE PACIFIC NORTHWEST MONDAY FOR INCREASING
OFFSHORE FLOW...WHICH SHOULD CONFINE THE FOG MORE TOWARD EUGENE
LATER MONDAY INTO TUESDAY. A COLDER SYSTEM IS EXPECTED TO BRING RAIN
AND MOUNTAIN SNOW BY WEDNESDAY...WITH SNOW LEVELS LOWERING WELL INTO
THE FOOTHILLS BY THURSDAY. LOW SNOW LEVELS WILL PERSIST THURSDAY
NIGHT INTO EARLY FRIDAY AS THE NEXT PACIFIC FRONT APPROACHES...BUT
WARMER AIR IS EXPECTED TO PUSH IN WITH THE FRONT LATER FRIDAY AND
SATURDAY.
&&
.UPDATE...BAROCLINIC ZONE WILL REMAIN DRAPED OVER THE AREA TONIGHT.
ANY MINIMAL FORCING ON THE FRONT WILL TAPER OFF TONIGHT...BUT EXPECT
A FEW MORE HOURS OF DRIZZLE AT THE COAST/COAST RANGE...AND IN THE
HIGHER TERRAIN. WINDS ARE EASING UP AND WE ARE STARTING TO SEE SOME
MORE FOG AND LOWERING OF THE CLOUD DECK...BUT FEEL THAT IT WILL BE A
LATER START TO MORE WIDESPREAD DENSE FOG...AND THIS IS CONFIRMED BY
THE HRRR SFC VISBY PROG SHOWING A LOWERING OF CIGS/REDUCED VISBYS
LATE TONIGHT INTO EARLY MONDAY. ISSUED A DENSE FOG ADVISORY FOR MUCH
OF THE VALLEY...THAT WILL AFFECT SOME AREAS FOR THE MONDAY MORNING
COMMUTE. WILL WATCH WEB CAMS CLOSELY TO SEE IF DENSE FOG BECOMES
MORE WIDESPREAD ALONG THE COAST. HAD SPOTTER REPORTS OF LOWERING
VSBYS NEAR TILLAMOOK AND ALREADY HAVE PRETTY THICK FOG AROUND
ASTORIA. /KMD
.SHORT TERM...TONIGHT THROUGH WEDNESDAY...A WEAK COLD FRONT STALLED
OVER OREGON EARLIER TODAY...AND IS NOW DISSIPATING AS A STATIONARY
FRONT ACROSS THE REGION. THE BULK OF THE PRECIPITATION MOVED THROUGH
WITH A FAST-MOVING SHORTWAVE EARLIER TODAY...BUT THERE ARE STILL SOME
AREAS OF LIGHT RAIN AND DRIZZLE WITHIN THE LEFTOVER LOW-LEVEL MOIST
LAYER. EXPECT THESE AREAS TO BECOME MORE CONFINED TO THE HIGHER
TERRAIN OVERNIGHT AS HIGH PRESSURE BUILDS IN FROM THE PACIFIC.
WITH RIDGING DEVELOPING AT THE SURFACE AND ALOFT...CONDITIONS WILL BE
IDEAL FOR INVERSION BUILDING TONIGHT. WITH ABUNDANT MOISTURE TRAPPED
WITHIN THE INVERSION EXPECT FOG TO BE FAIRLY WIDESPREAD
TONIGHT...BECOMING DENSE IN THE WILLAMETTE VALLEY. A THERMAL TROUGH
EXTENDING NORTHWARD FROM THE CALIFORNIA COAST SHOULD INDUCE SOME
NORTHERLY FLOW MONDAY...ALLOWING FOR SOME MIXING MOST AREAS. HOWEVER
THE NORTHERLY FLOW WILL PROBABLY CAUSE LEFTOVER LOW CLOUDS TO BANK UP
AGAINST THE SOUTH END OF THE WILLAMETTE VALLEY...LEADING TO A COOL
AND CLAMMY DAY WITH HIGHS AROUND 40 MONDAY AS MOST OTHER AREAS AIM
FOR 50 DEGREES...OR AT LEAST THE UPPER 40S IF CLOUDS ARE A BIT
PESKIER AS SOME GUIDANCE SUGGESTS. SHOULD BE A NICE DAY IN THE
FOOTHILLS AND CASCADES.
NORTHERLY FLOW WILL WANE MONDAY NIGHT AND TUESDAY...POSSIBLY ALLOWING
SOME FOG TO FORM IN THE VALLEYS AWAY FROM THE WEST END OF THE
COLUMBIA GORGE. WITH 12Z MET/MAV GUIDANCE SHOWING LOWER DEWPOINTS
OUTLYING VALLEYS...WILL HAVE A BETTER SHOT AT GETTING BELOW FREEZING
AND THUS AREAS OF FREEZING FOG TUE MORNING. WITH LIGHT FLOW AND
INCREASING HIGH CLOUDS TUESDAY ANY LOW CLOUDS SHOULD BE FAIRLY
PERSISTENT AND SLOW TO BURN OFF IN THE STRONGER INVERSION. WHILE
VALLEYS REMAIN IN THE UPPER 30S AND 40S...18Z NAM 850 MB TEMPS AROUND
+5 TO +6 DEG C SHOULD SUPPORT TEMPS IN THE MID TO UPPER 50S IN THE
FOOTHILLS ABOVE THE INVERSION. COASTAL AREAS SHOULD ALSO BE FAIRLY
MILD BOTH MONDAY AND TUESDAY.
MEANWHILE A SYSTEM PRESENTLY OUT IN THE PACIFIC NEAR 160W SHOULD
MERGE WITH A COLD GULF OF ALASKA LOW OVER THE NEXT 24-48 HOURS...
EVENTUALLY PUSHING A COLD FRONT FROM THE GULF OF ALASKA SOUTH TOWARD
THE PACIFIC NORTHWEST LATE TUESDAY. AT THIS POINT MODEL CONSENSUS
SHOWS FAIRLY LIGHT QPF...BUT THERE IS SOME POTENTIAL FOR A WEAK AND
BRIEF SUBTROPICAL TAP TO SET UP WITH THIS FRONT. EITHER WAY...RAIN
SHOULD SPREAD FROM NORTH TO SOUTH ACROSS THE FORECAST AREA TUE NIGHT
AND WED...FOLLOWED BY COLDER AIR WITH SNOW LEVELS FALLING INTO THE
COAST RANGE AND FOOTHILL ELEVATIONS BY WED NIGHT. WEAGLE
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY. THE COLD FRONT WILL
CONTINUE TO MOVE THROUGH THE AREA BY LATE WEDNESDAY NIGHT AND
PRECIPITATION WILL TAPER OFF LEAVING ONLY A FEW LINGERING SHOWERS BY
EARLY THURSDAY MORNING. THIS WILL BE IN THE FORM OF RAIN FOR THE
LOWER ELEVATIONS AND SNOW IN THE CASCADES AS THE SNOW LEVELS WILL
FALL BEHIND THE FRONT. THERE IS A CHANCE FOR SOME SNOW IN THE HIGHER
ELEVATIONS OF THE COAST RANGE...BUT THIS IS DEPENDENT UPON HOW FAST
SNOW LEVELS DROP BEFORE THE PRECIP ENDS.
THURSDAY WILL BE DRY UNDER NORTHERLY FLOW ALOFT AHEAD OF THE NEXT
SYSTEM. TIMING DIFFERENCES REMAIN BETWEEN FORECAST MODELS WITH THE
ARRIVAL OF THIS SYSTEM...WITH THE 12Z ECMWF STILL ABOUT 12 HRS
FASTER THAN THE GFS. IF THE SYSTEM DOES ARRIVE EARLIER...PRECIP MAY
BEGIN AS SNOW FOR AREAS SUCH AS THE COAST RANGE...WILLAPA HILLS...
AND CASCADE FOOTHILLS THROUGH EARLY FRIDAY MORNING. HOWEVER...THIS
WILL LIKELY BE RAIN FOR MOST OF THE AREA AS SNOW LEVELS QUICKLY
RISE...AND SNOW LEVELS SHOULD RISE ABOVE THE CASCADE PASSES BY
SATURDAY MORNING. THIS RAIN WILL CONTINUE INTO SATURDAY AND ENHANCED
BY A PASSING SHORTWAVE EMBEDDED IN THE UPPER LEVEL FLOW. ANOTHER
DISTURBANCE MAY IMPACT THE NORTHERN PARTS OF THE AREA BY SUNDAY...
BUT THIS FEATURE IS MUCH WEAKER IN THE 12Z ECMWF. CULLEN
&&
.AVIATION...GENERALLY IFR ALONG THE COAST AND IN THE INTERIOR
VALLEYS AS OF 04Z. HOWEVER...NOT NEARLY AS MUCH LIFR COMPARED TO
24 HOURS AGO. LIFR COVERAGE TO INCREASE THROUGH THE NIGHT WITH
ABUNDANT LOW LEVEL MOISTURE IN PLACE AND LITTLE IN THE WAY OF
WIND. MODELS SHOW A HINT OF N TO NE LOW-LEVEL FLOW DEVELOPING MON
AFTERNOON...WITH THE NAM THE MOST PRONOUNCED WITH IT. WOULD EXPECT
COASTAL SITES TO BECOME VFR BY AT LEAST 18Z MON...ESPECIALLY KONP.
INLAND VALLEYS SHOULD ALSO ACHIEVE VFR CONDITIONS...BUT PROBABLY
NOT UNTIL 20Z OR A BIT LATER. THE LOW-LEVEL NLY FLOW MAY KEEP KEUG
IN MVFR OR WORSE THE ENTIRE DAY.
KPDX AND APPROACHES...IFR TO LIFR CONDITIONS EXPECTED TO PERSIST
THROUGH AT LEAST 20Z MON. A BETTER CHANCE OF IMPROVING TO VFR MON
AFTERNOON WITH LIGHT LOW-LEVEL NE-E FLOW. WEISHAAR
&&
.MARINE...SEAS AT 00Z WERE RUNNING ABOUT 1-2 FT BELOW ENP GUIDANCE
VALID AT 00Z. SHORTLY BEFORE 04Z SEAS HAD RISEN TO 12-14
FT...CLOSE TO THE 06Z ENP FORECAST. THIS LONG-PERIOD SWELL TRAIN
WILL CONTINUE THROUGH MON AFTERNOON. SEAS MAY DROP BELOW 10 FT A
BIT EARLIER THAN GUIDANCE SUGGESTS...BUT WILL LEAVE THE SMALL
CRAFT ADVISORY TIMING AS IS.
LITTLE IN THE WAY OF WIND ISSUES FOR THE NEXT COUPLE OF DAYS.
MODELS...ESPECIALLY THE NAM...DEVELOP A THERMAL TROUGH ALONG THE
SOUTH OREGON COAST LATE TONIGHT THROUGH MON...WHICH COULD PRODUCE
SOME N-NE 20 KT GUSTS OVER THE FAR SRN WATERS. BELIEVE THE NAM MAY
BE A BIT OVERDONE WITH THIS THERMAL TROUGH FEATURE. ECMWF AND GFS
NOT NEARLY AS STRONG WITH IT.
ANOTHER WEAK FRONT IS EXPECTED TO PUSH THROUGH THE WATERS LATE
TUE. THE MODELS INDICATE LOW END SMALL CRAFT ADVISORY WINDS MAY BE
A POSSIBILITY IN THE NW POST FRONTAL WINDS ON WED. IN ADDITION
SEAS MAY BUILD BACK NEAR 10 FT WED AND WED NIGHT. WEISHAAR
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...DENSE FOG ADVISORY FOR THE WILLAMETTE VALLEY...GREATER PORTLAND
AREA AND LOWER COLUMBIA LATE TONIGHT THROUGH 10 AM MONDAY.
WA...DENSE FOG ADVISORY FOR THE GREATER VANCOUVER AREA AND LOWER COLUMBIA
LATE TONIGHT THROUGH 10 AM MONDAY.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM PST MONDAY
FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR
OUT 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM
PST MONDAY.
&&
$$
MORE WEATHER INFORMATION ONLINE AT..
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS PORTLAND OR
900 PM PST SUN DEC 15 2013
.SYNOPSIS...A WEAK STATIONARY FRONT IS DISSIPATING OVER OREGON THIS
EVENING LEAVING PLENTY OF LOW LEVEL MOISTURE BEHIND. THIS MOISTURE
WILL RESULT IN LOCALLY DENSE FOG TONIGHT AND MONDAY MORNING. HIGH
PRESSURE WILL BUILD INTO THE PACIFIC NORTHWEST MONDAY FOR INCREASING
OFFSHORE FLOW...WHICH SHOULD CONFINE THE FOG MORE TOWARD EUGENE
LATER MONDAY INTO TUESDAY. A COLDER SYSTEM IS EXPECTED TO BRING RAIN
AND MOUNTAIN SNOW BY WEDNESDAY...WITH SNOW LEVELS LOWERING WELL INTO
THE FOOTHILLS BY THURSDAY. LOW SNOW LEVELS WILL PERSIST THURSDAY
NIGHT INTO EARLY FRIDAY AS THE NEXT PACIFIC FRONT APPROACHES...BUT
WARMER AIR IS EXPECTED TO PUSH IN WITH THE FRONT LATER FRIDAY AND
SATURDAY.
&&
.UPDATE...BAROCLINIC ZONE WILL REMAIN DRAPED OVER THE AREA TONIGHT.
ANY MINIMAL FORCING ON THE FRONT WILL TAPER OFF TONIGHT...BUT EXPECT
A FEW MORE HOURS OF DRIZZLE AT THE COAST/COAST RANGE...AND IN THE
HIGHER TERRAIN. WINDS ARE EASING UP AND WE ARE STARTING TO SEE SOME
MORE FOG...BUT FEEL THAT IT WILL BE A LATER START TO MORE WIDESPREAD
DENSE FOG...AND THIS IS CONFIRMED BY THE HRRR SFC VISBY PROG SHOWING
A LOWERING OF CIGS/REDUCED VISBYS LATE TONIGHT INTO EARLY MONDAY. WE
HAVE A POTENTIAL FOR A DENSE FOG ADVISORY TO BE ISSUED
OVERNIGHT...JUST WORKING ON TIMING AS THIS WILL LIKELY AFFECT AREAS
FOR THE MONDAY MORNING COMMUTE. MAY SEE THIS COME OUT AS EARLY AS
THIS EVENING. /KMD
.SHORT TERM...TONIGHT THROUGH WEDNESDAY...A WEAK COLD FRONT STALLED
OVER OREGON EARLIER TODAY...AND IS NOW DISSIPATING AS A STATIONARY
FRONT ACROSS THE REGION. THE BULK OF THE PRECIPITATION MOVED THROUGH
WITH A FAST-MOVING SHORTWAVE EARLIER TODAY...BUT THERE ARE STILL SOME
AREAS OF LIGHT RAIN AND DRIZZLE WITHIN THE LEFTOVER LOW-LEVEL MOIST
LAYER. EXPECT THESE AREAS TO BECOME MORE CONFINED TO THE HIGHER
TERRAIN OVERNIGHT AS HIGH PRESSURE BUILDS IN FROM THE PACIFIC.
WITH RIDGING DEVELOPING AT THE SURFACE AND ALOFT...CONDITIONS WILL BE
IDEAL FOR INVERSION BUILDING TONIGHT. WITH ABUNDANT MOISTURE TRAPPED
WITHIN THE INVERSION EXPECT FOG TO BE FAIRLY WIDESPREAD
TONIGHT...BECOMING DENSE IN THE WILLAMETTE VALLEY. A THERMAL TROUGH
EXTENDING NORTHWARD FROM THE CALIFORNIA COAST SHOULD INDUCE SOME
NORTHERLY FLOW MONDAY...ALLOWING FOR SOME MIXING MOST AREAS. HOWEVER
THE NORTHERLY FLOW WILL PROBABLY CAUSE LEFTOVER LOW CLOUDS TO BANK UP
AGAINST THE SOUTH END OF THE WILLAMETTE VALLEY...LEADING TO A COOL
AND CLAMMY DAY WITH HIGHS AROUND 40 MONDAY AS MOST OTHER AREAS AIM
FOR 50 DEGREES...OR AT LEAST THE UPPER 40S IF CLOUDS ARE A BIT
PESKIER AS SOME GUIDANCE SUGGESTS. SHOULD BE A NICE DAY IN THE
FOOTHILLS AND CASCADES.
NORTHERLY FLOW WILL WANE MONDAY NIGHT AND TUESDAY...POSSIBLY ALLOWING
SOME FOG TO FORM IN THE VALLEYS AWAY FROM THE WEST END OF THE
COLUMBIA GORGE. WITH 12Z MET/MAV GUIDANCE SHOWING LOWER DEWPOINTS
OUTLYING VALLEYS...WILL HAVE A BETTER SHOT AT GETTING BELOW FREEZING
AND THUS AREAS OF FREEZING FOG TUE MORNING. WITH LIGHT FLOW AND
INCREASING HIGH CLOUDS TUESDAY ANY LOW CLOUDS SHOULD BE FAIRLY
PERSISTENT AND SLOW TO BURN OFF IN THE STRONGER INVERSION. WHILE
VALLEYS REMAIN IN THE UPPER 30S AND 40S...18Z NAM 850 MB TEMPS AROUND
+5 TO +6 DEG C SHOULD SUPPORT TEMPS IN THE MID TO UPPER 50S IN THE
FOOTHILLS ABOVE THE INVERSION. COASTAL AREAS SHOULD ALSO BE FAIRLY
MILD BOTH MONDAY AND TUESDAY.
MEANWHILE A SYSTEM PRESENTLY OUT IN THE PACIFIC NEAR 160W SHOULD
MERGE WITH A COLD GULF OF ALASKA LOW OVER THE NEXT 24-48 HOURS...
EVENTUALLY PUSHING A COLD FRONT FROM THE GULF OF ALASKA SOUTH TOWARD
THE PACIFIC NORTHWEST LATE TUESDAY. AT THIS POINT MODEL CONSENSUS
SHOWS FAIRLY LIGHT QPF...BUT THERE IS SOME POTENTIAL FOR A WEAK AND
BRIEF SUBTROPICAL TAP TO SET UP WITH THIS FRONT. EITHER WAY...RAIN
SHOULD SPREAD FROM NORTH TO SOUTH ACROSS THE FORECAST AREA TUE NIGHT
AND WED...FOLLOWED BY COLDER AIR WITH SNOW LEVELS FALLING INTO THE
COAST RANGE AND FOOTHILL ELEVATIONS BY WED NIGHT. WEAGLE
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY. THE COLD FRONT WILL
CONTINUE TO MOVE THROUGH THE AREA BY LATE WEDNESDAY NIGHT AND
PRECIPITATION WILL TAPER OFF LEAVING ONLY A FEW LINGERING SHOWERS BY
EARLY THURSDAY MORNING. THIS WILL BE IN THE FORM OF RAIN FOR THE
LOWER ELEVATIONS AND SNOW IN THE CASCADES AS THE SNOW LEVELS WILL
FALL BEHIND THE FRONT. THERE IS A CHANCE FOR SOME SNOW IN THE HIGHER
ELEVATIONS OF THE COAST RANGE...BUT THIS IS DEPENDENT UPON HOW FAST
SNOW LEVELS DROP BEFORE THE PRECIP ENDS.
THURSDAY WILL BE DRY UNDER NORTHERLY FLOW ALOFT AHEAD OF THE NEXT
SYSTEM. TIMING DIFFERENCES REMAIN BETWEEN FORECAST MODELS WITH THE
ARRIVAL OF THIS SYSTEM...WITH THE 12Z ECMWF STILL ABOUT 12 HRS
FASTER THAN THE GFS. IF THE SYSTEM DOES ARRIVE EARLIER...PRECIP MAY
BEGIN AS SNOW FOR AREAS SUCH AS THE COAST RANGE...WILLAPA HILLS...
AND CASCADE FOOTHILLS THROUGH EARLY FRIDAY MORNING. HOWEVER...THIS
WILL LIKELY BE RAIN FOR MOST OF THE AREA AS SNOW LEVELS QUICKLY
RISE...AND SNOW LEVELS SHOULD RISE ABOVE THE CASCADE PASSES BY
SATURDAY MORNING. THIS RAIN WILL CONTINUE INTO SATURDAY AND ENHANCED
BY A PASSING SHORTWAVE EMBEDDED IN THE UPPER LEVEL FLOW. ANOTHER
DISTURBANCE MAY IMPACT THE NORTHERN PARTS OF THE AREA BY SUNDAY...
BUT THIS FEATURE IS MUCH WEAKER IN THE 12Z ECMWF. CULLEN
&&
.AVIATION...GENERALLY IFR ALONG THE COAST AND IN THE INTERIOR
VALLEYS AS OF 04Z. HOWEVER...NOT NEARLY AS MUCH LIFR COMPARED TO
24 HOURS AGO. LIFR COVERAGE TO INCREASE THROUGH THE NIGHT WITH
ABUNDANT LOW LEVEL MOISTURE IN PLACE AND LITTLE IN THE WAY OF
WIND. MODELS SHOW A HINT OF N TO NE LOW-LEVEL FLOW DEVELOPING MON
AFTERNOON...WITH THE NAM THE MOST PRONOUNCED WITH IT. WOULD EXPECT
COASTAL SITES TO BECOME VFR BY AT LEAST 18Z MON...ESPECIALLY KONP.
INLAND VALLEYS SHOULD ALSO ACHIEVE VFR CONDITIONS...BUT PROBABLY
NOT UNTIL 20Z OR A BIT LATER. THE LOW-LEVEL NLY FLOW MAY KEEP KEUG
IN MVFR OR WORSE THE ENTIRE DAY.
KPDX AND APPROACHES...IFR TO LIFR CONDITIONS EXPECTED TO PERSIST
THROUGH AT LEAST 20Z MON. A BETTER CHANCE OF IMPROVING TO VFR MON
AFTERNOON WITH LIGHT LOW-LEVEL NE-E FLOW. WEISHAAR
&&
.MARINE...SEAS AT 00Z WERE RUNNING ABOUT 1-2 FT BELOW ENP GUIDANCE
VALID AT 00Z. SHORTLY BEFORE 04Z SEAS HAD RISEN TO 12-14
FT...CLOSE TO THE 06Z ENP FORECAST. THIS LONG-PERIOD SWELL TRAIN
WILL CONTINUE THROUGH MON AFTERNOON. SEAS MAY DROP BELOW 10 FT A
BIT EARLIER THAN GUIDANCE SUGGESTS...BUT WILL LEAVE THE SMALL
CRAFT ADVISORY TIMING AS IS.
LITTLE IN THE WAY OF WIND ISSUES FOR THE NEXT COUPLE OF DAYS.
MODELS...ESPECIALLY THE NAM...DEVELOP A THERMAL TROUGH ALONG THE
SOUTH OREGON COAST LATE TONIGHT THROUGH MON...WHICH COULD PRODUCE
SOME N-NE 20 KT GUSTS OVER THE FAR SRN WATERS. BELIEVE THE NAM MAY
BE A BIT OVERDONE WITH THIS THERMAL TROUGH FEATURE. ECMWF AND GFS
NOT NEARLY AS STRONG WITH IT.
ANOTHER WEAK FRONT IS EXPECTED TO PUSH THROUGH THE WATERS LATE
TUE. THE MODELS INDICATE LOW END SMALL CRAFT ADVISORY WINDS MAY BE
A POSSIBILITY IN THE NW POST FRONTAL WINDS ON WED. IN ADDITION
SEAS MAY BUILD BACK NEAR 10 FT WED AND WED NIGHT. WEISHAAR
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM PST MONDAY
FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR
OUT 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM
PST MONDAY.
&&
$$
MORE WEATHER INFORMATION ONLINE AT..
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
329 AM CST MON DEC 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 329 AM CST MON DEC 16 2013
MONITORING DYNAMIC SYSTEM NEAR LAKE WINNIPEG AND THE RADAR BAND
DEVELOPING ACROSS ND AT 08Z. OTHER RADAR ECHO AND SOME SCT REPORTS
OF SN- BEING REPORTED ALONG WARM ADVECTION ARM EXTENDING THROUGH
THE EASTERN DAKOTAS AND INTO THE MN RIVER VALLEY. THIS SYSTEM WAS
HANDLED WELL AND FEW CHANGES WERE MADE TO THE ONGOING FORECAST
FOR TODAY EXCEPT FOR TIMING.
STRONG CIRCULATION CLEARLY SEEN IN GOES WATER VAPOR IMAGERY NEAR
LAKE WINNIPEG AND THIS SYSTEM AND ITS POTENTIAL VORTICITY
ADVECTION WILL DIG TOWARD LAKE SUPERIOR AND DRAG GOOD DYNAMICS
ACROSS NORTHERN WI TODAY. THIS POTENTIAL VORTICITY ADVECTION...IN
COMBINATION WITH WARM ADVECTION ALONG THE THERMAL RIBBON FROM
700-900 MB...AND SOME MODERATE 250MB JET EXIT REGION DIVERGENCE WILL
PRODUCE A SWATH OF 1-2 SNOW TODAY. HRRR TRENDS SHOW A SOMEWHAT
NARROW BAND SHIFTING ACROSS WI DURING THE DAY...WITH ABOUT 2
HOURS OF SNOW AT ANY ONE POINT. HI-RES WINDOWS FROM NCEP NMM/ARW
16.00Z RUNS SUGGEST SIMILAR TIMING TODAY AND INTENSITY...BUT MAYBEA
BIT WIDER BAND.
A BREAK OCCURS LATE TODAY AND THIS EVENING...BUT HAVE INCREASED
THE SNOW CHANCES TONIGHT WITH ANOTHER 1-2 INCHES NOW EXPECTED
ALONG AND NORTH OF I-90. SECONDARY SHORTWAVE TROUGH RIDING ON THE
NOSE OF THE POLAR JET WILL COME ACROSS THE AREA TONIGHT...A DIRECT
HIT. SO...SNOWFALL SHOULD BREAK OUT AGAIN ALONG AND NORTH OF I-90
AROUND MIDNIGHT...WITH AREAS SOUTH A BIT MORE LIMITED IN THEIR
SATURATION. THE ENERGY WILL SHIFT EAST BY SUNRISE. MODEL GUIDANCE
HAS SOME SPREAD ON THE LOCATION OF THE SNOW WITH SOME SOLUTIONS
FURTHER SOUTH...BUT IT SEEMS THE TRACK OF THE WAVE AND THE JET
FLOW ALOFT WOULD SHOW PREFERENCE TO THE I-90 CORRIDOR AND NORTH.
NEW SNOW TOTALS BY TUESDAY MORNING WILL BE IN THE 1-3 INCH RANGE
WITH THE 3 INCH TOTALS MOST LIKELY ALONG AND NORTH OF I-94. HAVE
COLLABORATED WITH SURROUNDING NWS OFFICES AND WILL HOLD OFF ON THE
ADVISORY AS THE TWO SYSTEMS SHOULD BE SPACED IN TIME...AND THE 3
INCH TOTALS SHOULD BE THE HIGHER END RATHER THAN THE RULE. WILL
COVER IT IN THE HAZ WEATHER OUTLOOK AND POSSIBLY A SPECIAL
STATEMENT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 329 AM CST MON DEC 16 2013
TUESDAY LOOKS TO BE A BREEZY DAY BEHIND THIS WAVE...IN THE 15-25
MPH RANGE. THEN...RIDGE BUILDING STARTS WITH MAINLY SUNSHINE
EXCEPT ACROSS THE NORTH WHERE THE STORM TRACK SHIFT TO. A STRONG
SHORTWAVE TRAVELS ALONG THE U.S. CANADA BORDER AND MORE WARM
ADVECTION IS EXPECTED TUESDAY NIGHT AND WEDNESDAY NIGHT...WITH
PRECIPITATION STILL OFF TO THE NORTH.
THURSDAY-SUNDAY...
SIGNALS CONTINUE IN THE MODEL GUIDANCE FOR PRECIPITATION TO
SPREAD IN LATE THURSDAY AND THURSDAY NIGHT WITH THE FIRST
SHORTWAVE TROUGH EJECTION FROM THE LONGWAVE DEVELOPING ACROSS THE
WRN CONUS. THE SIGNAL IS REMAINING CONSISTENT WITH THE GFS AND GFS
ENSEMBLES STILL THE COLDER SOLUTIONS...WITH THE FRONTAL BOUNDARY
REMAINING THROUGH IL AND THE SOUTHERN FORECAST AREA IN SUB-ZERO
SURFACE TEMPERATURES. ACROSS ABOUT THE SOUTHERN TWO-THIRDS...THE
LIFT APPEARS LIMITED WITH ABUNDANT MOISTURE IN THE 0-3KM
LAYER...BUT NOT ABOVE IN THE ICE PRODUCING LAYER. THUS THE GFS HAS
A 3KM DEEP SUPERCOOLED LIQUID LAYER...CONSISTENT OVER THE PAST
RUNS. THIS IS A FZDZ/FZRA SITUATION AND HOLD THE POTENTIAL FOR
ICING. THE WARMER SOLUTIONS OF THE ECMWF/CANADIAN MODELS WOULD
CAUSE RAIN IN THE SOUTH. THE SPREAD IN THE TEMPERATURE PROFILE IS
STILL VERY LARGE THURSDAY/THU NIGHT AMONG THE WARM VERSUS COLD
SOLUTIONS...WITH SURFACE HIGHS 28F IN THE GFS THURSDAY...AND 45F
IN THE CANADIAN MODEL...WITH THE 16.00Z ECMWF IN THE MIDDLE. THAT
IS WHERE OUR FORECAST TEMPERATURES REMAIN...THUS A MORE LIMITED
ICING AREA IN NERN IA AND SWRN WI...AND AMOUNTS HAVE TRENDED
LOWER...LESS THAN 0.10 INCHES.
TO THE NORTH ON THURSDAY NIGHT IT APPEARS THE NORTHERN STREAM WAVE
WILL PROVIDE ENOUGH FORCING FOR DEEP SATURATION AND LIGHT SNOWFALL
THAT WOULD ACCUMULATE AROUND AN INCH. CURRENT FORECAST HAS THIS
LIQUID VERSUS SNOW OUTCOME ALONG A KMCW-KISW LINE...WITH SNOW
NORTHWEST. OVERALL...DID RAISE PRECIPITATION CHANCES BUT OVERALL
CHANGES WERE MINOR WITH THAT SYSTEM.
THE LONGWAVE TROUGH DIGS DEEPLY INTO MEXICO ON THE WEEKEND AND THERE
IS HIGH SPREAD ON THE OUTCOMES FOR THIS MAJOR ENERGY. THERE WILL BE
MAJOR WINTER WEATHER WITH THIS SYSTEM...BUT THE FURTHER SOUTH IT
DIGS...THE MORE THE AREA WOULD SEEM TO REMAIN UNDER THE NRN
STREAM OF ENERGY AND NOT BE AFFECTED. HAVE SMALL CHANCES OF
PRECIPITATION IN THE FORECAST FOR NOW MAINLY FOR E/SE AREAS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1115 PM CST SUN DEC 15 2013
THE BAND OF LIGHT SNOW THIS EVENING HAS PERSISTED LONGER AND MOVED
A LITTLE FARTHER NORTHEAST THAN PREVIOUSLY EXPECTED. HOWEVER...IT
CONTINUES TO MOVE SOUTHEAST AND WILL BE PAST BOTH TAF SITES BY
06Z. LOOKING UPSTREAM BEHIND THE SNOW BAND...VFR CONDITIONS
EXPECTED TO PREVAIL THROUGH THE NIGHT. THE NEXT SHORT WAVE TROUGH
CONTINUES TO MOVE SOUTHEAST ACROSS SASKATCHEWAN AND WILL MOVE
ACROSS THE UPPER MIDWEST MONDAY. GOOD FORCING FROM THIS WAVE
EXPECTED TO PRODUCE ANOTHER BAND OF LIGHT SNOW DURING THE DAY. THE
15.21Z SREF CONTINUES TO INDICATE IFR CONDITIONS IN THE LIGHT SNOW
AND WILL SHOW THIS AT BOTH TAF SITES FROM MID MORNING INTO THE
EARLY AFTERNOON. THE 16.00Z NAM CONTINUES TO SUGGEST THE
POSSIBILITY OF LOOSING ICE IN THE CLOUDS AS THE PRECIPITATION IS
COMING TO AN END FOR THE POSSIBILITY OF SOME FREEZING DRIZZLE.
CONFIDENCE IS NOT HIGH IN THIS OUTCOME AND OPTED TO NOT INCLUDE AT
THIS TIME. CONDITIONS SHOULD GO BACK UP TO VFR BEHIND THE SNOW
BAND ONLY TO COME BACK DOWN TO MVFR DURING THE LATE EVENING AS THE
NEXT SHORT WAVE TROUGH APPROACHES. THIS WAVE WILL PRODUCE YET
ANOTHER BAND OF LIGHT SNOW OVERNIGHT MONDAY AND THE NEXT FORECAST
WILL HAVE TO ADDRESS THIS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...04
Area Forecast Discussion
National Weather Service Lincoln IL
1000 AM CST Mon Dec 16 2013
.DISCUSSION...
ISSUED 1000 AM CST Mon Dec 16 2013
Clouds currently blanket most of central Illinois in the wake of
a weak clipper system that tracked through the region overnight.
Trailing frontal boundary stretches from southern Illinois
northwestward into the Dakotas. Immediately north of the
boundary, low clouds and fog persist from near Terre Haute,
Indiana westward to Quincy. With winds expected to remain very
light from the east/northeast until later this afternoon when the
front begins to lift back northward, think clouds will hold firm
across the area. The exception will be across the far southern
KILX CWA around Flora and Lawrenceville where partly to mostly
sunny skies will be observed. Meanwhile, next clipper system is
currently evident on water vapor imagery over northern Minnesota.
This system is bringing light snow to much of Minnesota into
northern Iowa, with its projected trajectory to remain mostly
north of central Illinois today. 12z NAM forecast soundings remain
quite dry and latest HRRR keeps radar echoes further north. Will
therefore only mention a chance for flurries along/north of I-74
this afternoon/evening. Zone update has already been issued.
Barnes
&&
.AVIATION...
ISSUED 600 AM CST Mon Dec 16 2013
MVFR conditions will prevail for much of the next 18 hours as one
clipper system departs early this morning and another arrives this
afternoon. There is a possibility of a brief period of VFR
conditions as satellite images show a small area of higher clouds and
clearing west of PIA and SPI, moving east. Have kept the TAFs on
the pessimistic side as the breaks in the clouds have not been
consistent.
High pressure passing across Wisconsin and far northern IL should
should provide some subsidence for the morning to keep additional
snowfall to a minimum. Afternoon flurries may develop north of a
line from Canton to Mattoon, as the next clipper starts to affect
the area. No snow accumulation is expected, an no mention of snow
was put in the TAFs yet.
Winds will be light northeast to start the day, then winds will
become south by afternoon as return flow sets up behind the
departing high pressure. Directions will eventually veer around to
the west tonight as the clipper passes. Winds speeds should
remain less than 10kt for the most part under the weak pressure
gradient.
Shimon
&&
.PREV DISCUSSION...
ISSUED 256 AM CST Mon Dec 16 2013
Weak high pressure over much of the Midwest with northwesterly
flow aloft ushering in a couple of clipper systems in the short
term. Snow coming to an end this morning over ILX, but first
issues with the forecast revolve around the resolution of the next
system moving in later this afternoon/evening. Ridge building in
the SW will eventually result in some moderation of the
temperatures in the region, but existing snow field will counter
the warm up as well. Influence of the snowpack not represented
well in the models. In addition, GFS and ECMWF starting to come
more into line with the next major system next weekend. However,
the details are the fine line with major ramifications to the
thermal profile and resultant precip type.
SHORT TERM...Today and Tomorrow...
Cold and cloudy conditions continue as one clipper pulls away from
the region and another comes in on its heels later this afternoon.
Snow showers should remain mainly to the NE, but considering the
more southerly track of this mornings wave, will keep slight
chance pops in the NE. Little to no accumulations expected and
will keep the QPF low. Temperatures a little under guidance today
as the impact of the snow is not showing up enough in the models.
Another cold overnight, and temperatures begin to moderate with
more westerly flow at the sfc for Tuesday. Still concerned that
the forecast is a couple degrees too high, particularly in the
south. Winds becoming more southwesterly for Tuesday night,
especially after midnight, ushering in warmer air with a bit more
moisture. Moving this RH over a snowpack brings the threat of fog.
However, between the winds staying up just a bit and with the
models having a major issue with the boundary layer, confidence is
low.
LONG TERM...Wednesday through Sunday...
Low confidence continues with the temperatures through the middle
of the week. Will depend greatly on the persistence of the WAA
from the SW and the snow melt. After the main trof pulls to the
east Tues night/Wed, flow eventually moves to a more SWrly pattern
with a trof digging in over the west coast. Deep upper low
becoming briefly cut off in the GFS and ECMWF as the models start
to converge. SWrly flow setting up and putting ILX in a transition
zone temperature wise with the initial passage of the front on
Thurs night/Friday. Front moving into and stalling out just to the
south over the Ohio River Valley. Location of the boundary as a
series of upper waves eject out and along said front will make a
major difference on the forecast. Northerly extent of the precip
with respect to the front is the main issue for the forecast as
well as how deep into the cold air the precip reaches. Latest
ECMWF even pointing to ice, while GFS maintains mostly snow after
a transitional mix. Precip type is still ambiguous, much less QPF
depending on extent of precip with the front stalled to the
south. A series of small waves rippling along the stalled front
keeps high chance pops in the AllBlend for Fri through Sunday and
will leave that as is.
HJS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
518 AM CST MON DEC 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CST MON DEC 16 2013
TODAY AND TONIGHT...A POWERFUL THERMAL RIDGE WILL CONTINUE OPERATING
ACROSS THE FORECAST AREA. A WEAK COLD FRONT ACROSS SERN MT THIS
MORNING COULD DROP THROUGH THE NERN PORTION OF THE FCST AREA THIS
AFTERNOON BUT TEMPS BEHIND THE FRONT ARE ABOVE FREEZING SO NO
SIGNIFICANT COOLING IS EXPECTED. THE TEMPERATURE FCST TODAY FOLLOWS
THE WARMEST MODELS WHICH ARE THE HRRR AND RAP FORECASTING MID TO
UPPER 50S ACROSS SWRN NEB. THESE MODELS HAVE VERIFIED THE BEST OVER
THE WEEKEND. 40S ARE EXPECTED ACROSS THE SNOW COVER NORTH AND THIS
SNOW IS MELTING.
WINDS AT H850 MB CONTINUE AT 30 TO 40 KT TODAY WITH 500M AGL WINDS
OF 20 TO 25 KTS. THIS WOULD PRODUCE 15 TO 25 MPH WINDS AT THE SFC.
THE MID LEVEL CLOUD SHIELD ACROSS WRN SD AND ERN MT IS EXPECTED TO
SLICE THROUGH THE NERN PORTION OF THE FCST AREA TODAY WITH SCT-BKN
CIRRUS SOUTH AND WEST.
HIGH CLOUDS ARE EXPECTED TONIGHT AND THE NAM SUGGESTED MID LEVEL
CLOUDS NORTH AND EAST. ALL OF THESE CLOUDS SHOULD LIMIT RADIATIONAL
COOLING AND THE BEST GUESS WITH LOWS TONIGHT IS 20S WITH UPPER 20S
UNDER THE MID LEVEL CLOUD DECK. H850 MB WINDS WEAKEN TO 10 TO 25 KTS
WEST WHICH WOULD SUPPORT MODEST RADIATIONAL COOLING DESPITE THE
CLOUD COVER. 30 TO 40KT H850 WINDS CONTINUE NORTH AND EAST
SUPPORTING THE WARMER LOWS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 356 AM CST MON DEC 16 2013
PRIMARY FORECAST CONCERNS DEAL WITH TEMPERATURES THE NEXT SEVERAL
DAYS...THEN TURNS TO STRONG FRONTAL PASSAGE THURSDAY WITH COLDER
TEMPERATURES AND POSSIBLY SNOW FOR PARTS OF THE AREA.
RIDGING ALOFT WILL BUILD OVER THE CENTRAL PLAINS ON TUESDAY IN THE
WAKE OF AN UPPER LEVEL SHORTWAVE TROUGH. STILL EXPECT TO SEE AN
INFLUENCE ON TEMPERATURES OVER THE NORTHERN PARTS OF NEBRASKA FROM
THE SNOWPACK...HOWEVER WITH TEMPERATURES RISING ABOVE FREEZING
SHOULD CONTINUE TO SEE THE SNOW MELT IN THE COMING DAYS. DO HAVE A
WARMING TREND FOR THE SNOWPACK LOCATIONS...HOWEVER DIDN/T GO TOO
WARM YET UNTIL START TO SEE MUCH LESS INFLUENCE FROM THE SNOW. WHERE
THE GROUND IS DRY...LOOKING AT HIGHS 10 TO 15 DEGREES WARMER IN THE
50S TO NEAR 60 ON TUESDAY.
THE UPPER LEVEL LOW CURRENTLY OVER ALASKA...AS WELL AS THE UPPER LOW
OFF THE CALIFORNIA COAST WILL BOTH MAKE THEIR WAY ONTO THE WEST
COAST TUESDAY NIGHT AND WEDNESDAY. THESE TWO SYSTEMS WILL STAY
SEPARATE...BUT WILL BOTH WORK TO DEEPEN THE TROUGH ACROSS THE
WESTERN CONUS. AS THIS OCCURS...THE THERMAL RIDGE WILL STRENGTHEN
WITH 850MB TEMPERATURES NEARING 16C. DID INCREASE LOWS FOR TUESDAY
NIGHT DUE TO THE WARMING EXPECTED...HOWEVER WITH FAIRLY LIGHT WINDS
AND DEWPOINTS IN THE UPPER TEENS AND LOW 20S...MAY STILL GET
TEMPERATURES TO FALL INTO THE MID AND UPPER 20S. THIS PERIOD MAY
NEED TO BE ADJUSTED IN COMING FORECASTS. THEN FOR WEDNESDAY...SOME
PORTIONS OF SOUTHWEST NEBRASKA SHOULD APPROACH OR EXCEED 60 DEGREES.
AGAIN...AREAS ACROSS THE NORTH ARE QUESTIONABLE DUE TO THE SNOWPACK.
WILL SEE HOW THE NEXT COUPLE OF DAYS MELT THE SNOW AND WILL ADJUST
HIGHS IN THESE AREAS AS NEEDED. WINDS LOOK TO BE PRETTY LIGHT ON
WEDNESDAY TO LIMIT THE MIXING WITH MODELS ONLY MIXING TO 850MB OR
LOWER. IF DEEPER MIXING CAN BE REALIZED TEMPERATURES WILL BE TOO LOW
AND NEED TO BE ADJUSTED UPWARDS. FOR EXAMPLE...AT LBF MIXING TO
850MB WEDNESDAY AFTERNOON WOULD BRING A HIGH OF 64 DEGREES.
IS SOME DIFFERENCES ON TIMING OF THE ARCTIC FRONT ON
THURSDAY...WHICH THEN TRANSLATES TO LOWER CONFIDENCE ON HIGHS.
LOOKING AT THE 16.00Z MODELS...THE OPERATIONAL GFS HAS STAYED FAIRLY
SIMILAR IN TIMING WHICH IS THE COLDEST SOLUTION. THIS WOULD SUGGEST
HIGHS FROM THE UPPER TEENS OVER NORTH CENTRAL NEBRASKA TO THE MID
30S IN THE SOUTHWEST. HOWEVER THE GFS ENSEMBLES ARE SHOWING A
VARIETY OF SOLUTIONS AS IT SHOWS A DIFFERENCE OF 5 STANDARD
DEVIATIONS FOR MUCH OF THE FORECAST WHICH TRANSLATES TO A 20 DEGREE
DIFFERENCE AMONG JUST THE GFS SOLUTIONS. THE ECMWF DID SPEED THE
FRONT UP SLIGHTLY WITH THE 16.00Z RUN...HOWEVER THE GEM SLOWED IT
DOWN. WITH THE WIDE VARIETY OF SOLUTIONS AND LOWER CONFIDENCE WILL
KEEP THE FORECAST FAIRLY SIMILAR TO THE ONGOING FORECAST UNTIL THERE
IS BETTER SUPPORT TO GO COLDER.
IT DOES CONTINUE TO LOOK LIKE THERE WILL BE SOME POST-FRONTAL
PRECIPITATION...HOWEVER IT LOOKS LIKE VERY LIGHT PRECIPITATION. IN
THE UPPER LEVEL PATTERN...THE UPPER LOW NOW OFF THE CALIFORNIA COAST
WILL MOVE ACROSS THE CENTRAL PLAINS JUST AHEAD OF THE ARCTIC FRONT
/WITH LITTLE OR NO IMPACT IN THE SENSIBLE WEATHER/...AND WITH THE
WEST COAST SYSTEM DIGGING INTO SOUTHERN CALIFORNIA ON
THURSDAY...THERE ISN/T A GOOD MOISTURE FEED INTO THE AREA AS THE
ARCTIC FRONT PASSES. THIS WILL LEAD TO A DISJOINTED ATTEMPT AT
PRECIPITATION AS LIFT IS NOT IN THE AREA WHEN THE COLUMN SEES THE
GREATEST AMOUNT OF MOISTURE...WHILE THE MODELS ARE ALSO SHOWING A
DRY LAYER AROUND 700MB TO ALSO INHIBIT PRECIPITATION. CURRENT
FORECAST LIMITS THE PRECIPITATION TO MAINLY THE NORTHWEST HALF OF
THE FORECAST AREA. HAVE BEEN WATCHING A SIGNAL FOR DRIZZLE ON
THURSDAY OVER THE PAST FEW DAYS...AND ALTHOUGH SOUNDINGS WON/T
DISCOUNT IT RIGHT NOW WITH THE DRY LAYER EXPECTED...THEY ARE ALSO
SHOWING ENOUGH DRY AIR RIGHT AT THE SURFACE WHICH MAY KEEP ANY
DRIZZLE FROM BEING A THREAT. THEN AS THE COLUMN COOLS FURTHER WITH
THE COLD AIR INTRUSION...AND THE DRY LAYER GOES AWAY...DRIZZLE
POTENTIAL WILL DIMINISH WITH ONLY SNOW CHANCES. WILL CONTINUE TO
KEEP THE DRIZZLE MENTION OUT OF THE FORECAST FOR NOW AND WATCH IN
THE COMING DAYS.
BEYOND THURSDAY NIGHT THE MODELS ARE TRYING TO KICK OUT THE COLD AIR
TO BRING MORE SEASONABLE TEMPERATURES TO THE FORECAST AREA INTO NEXT
WEEKEND. HOWEVER...THE GFS ENSEMBLE MEMBERS ARE ALL OVER THE BOARD
WITH STANDARD DEVIATIONS OF 5 TO 7 ON HIGHS AND LOWS FRIDAY THROUGH
SUNDAY SO CONFIDENCE IS NOT REAL HIGH AT THIS POINT ON TEMPERATURES
THROUGH THAT TIME FRAME AND HAVE USED A CONSENSUS APPROACH FOR THE
FORECAST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 514 AM CST MON DEC 16 2013
VFR IS EXPECTED ALL AREAS TODAY AND TONIGHT.
SCT-BKN MID AND HIGH LEVEL CLOUDS WILL CONTINUE MOVING SOUTHEAST
THROUGH THE REGION.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...BROOKS
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1026 AM EST MON DEC 16 2013
.SYNOPSIS...
A SERIES OF CLIPPERS WILL BRING PERIODS OF LIGHT SNOW OR SNOW
SHOWERS TO CENTRAL NEW YORK AND NORTHEAST PENNSYLVANIA THROUGH
MIDWEEK. LAKE EFFECT SNOW SHOWERS WILL ALSO BE POSSIBLE AT TIMES
EAST AND SOUTHEAST OF LAKE ONTARIO. TEMPERATURES WILL BEGIN TO
MODERATE BY THE END OF THE WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
KBGM AND KTYX 88D/S CONT TO SHOW A NARROW LES BAND ACRS LAKE
ONTARIO E OF SODUS BAY INTO NW ONONDAGA CO WHERE IT BECOMES MORE
DIFFUSE. VIS SATL IMAGERY ALSO SHOWS THIS BAND WHICH EVENTUALLY
SNAKES DOWN THRU SRN MADISON...OTSEGO TO SCHOHARIE COUNTIES. THE
BAND LOSES ITS ORGANIZATION IN THE MTNS OF CORTLAND SRN MADISON
AND CHENANGO/OTSEGO CO/S. THE FLOW WAS RATHER LIGHT IN THE SFC
LAYER RUNNING LESS THAN 10 KNOTS FROM THE W OR NW. BUT THE 925 MB
FLO REMAINS ARND 10-15 KTS AND CONTS TO DIRECT LAKE MOISTURE IN NC
NY FROM LAKE ONTARIO THRU THE AFTERNOON ON A 290 TO 300 DEGREE
FLOW. TEMPS WERE VERY COLD UNDER THE INVERSION WHICH WERE ARND
-20C NR 7000 FEET AGL. THE INVERSION LOWERS FROM 7000 FEET TO 3000
FEET AGL BY 23Z. THIS OCCURS AS THE COLD BUILDS IN AT LOWER LEVELS
WITH -18C AT 3000 FEET AGL BY 22Z AS PER LATEST RAP MODEL SOUNDING
AT KSYR. THE MEAN WIND BELOW THE INVERSION REMAINS FROM 290-300
DEGREES SO WILL CONT WITH CAT TO LIKELY POPS ACRS ONONDAGA TO
MADISON/SRN ONEIDA CO/S WITH JUST MINOR TWEAKS FROM PREV SHIFT.
HAVE 2-4 INCHES OF SNOW FALLING UP THERE BY LATE EVENING. DECIDED
AGAINST AN LES ADVY BECAUSE THERE WAS SHEAR IN THE LOW-
LEVELS...THE FLO WEAKENS LATER THIS AFTERNOON AND THERE WAS LARGE
SCALE SUBSC PUSHING THE INVERSION DOWN.
REST OF CWA WILL SEE SCT-BKN SC WITH FLURRIES AS THE MAX GROWTH
ZONE FOR ICE CRYSTALS IS NOT FAR ABV THE SFC. THIS MEANS THAT ANY
LIFTG EITHER OROGRAPHIC OR SIMPLY SOME WEAK CONVECTIVE OVERTURNING
IN AN SC CLOUD CUD PRODUCE A FEW FLAKES FOR THE REMAINDER OF THE
AFTERNOON.
SUBSC CONTS TO WORK IN ACRS THE CWA TONIGHT. THE LES WILL
EVENTUALLY WEAKEN AND SHIFT N OF THE CWA AS THE FLOW TURNS MORE
SWRLY BY 3Z OR SO. CLDS FROM NEXT SYSTEM WILL ADVECT OVHD LATER IN
THE NIGHT. HENCE I SEE MAINLY CLR SKIES MUCH OF CWA LEADING TO
SIGNIFICANT NET RAD COOLING IN THE EVENING...THINK TEMPS WILL FALL
QUICKLY...THEN REBOUND SOME LATE TONIGHT AS THE CLDS INCREASE AND
THICKEN. LATEST LAV GUIDC SUGGESTS THIS.
PREVIOUS DISCUSSION IS BELOW...
445 AM UPDATE...LES ADVISORY FOR NRN ONEIDA CANCELLED. PREV BLO...
ARCTIC FNT ENTERING THE NRN CWA EARLY THIS MRNG SHIFTING THE LOW
LVL FLOW TO MORE OF A NWLY DIRECTION. LES SNOW WILL LIKELY REMAIN
OVER ONON/MADISON AND FAR SRN ONEIDA TDA. VERY DRY LOW LVL AIR
WORKING INTO THE RGN BEHIND THIS FNT...AND LOW LVL FLOW WEAKENS
LATER THIS MRNG. XPCT ACCUMS GNRLY IN THE 2-3 INCH RNG FOR MUCH OF
THIS AREA TDA. THIS ACTIVITY WILL GRADUALLY SHIFT NWD LATE TDA
INTO THE EVNG HRS AS LOW LVL FLOW BACKS. SCT -SHSN ACRS PORTIONS
OF THE SRN TIER INTO NE PA THIS MRNG DUE TO ERIE STREAMER.
LATE TNGT NXT S/WV...CRNTLY OVER SRN CANADA...WILL DIVE SEWD INTO
THE FCST AREA. AREA OF LGT SNOW WILL BEGIN TO WORK INTO THE RGN
AFTER 06Z. MIN TEMPS TNGT LIKELY TO BE ARND 06Z WITH STEADY OR
SLOWLY RISING TEMPS AFTERWARDS. THIS AREA OF SNOW SHUD PUSH EWD
AND OUT OF THE RGN BY LATE MRNG OR EARLY AFTN...BUT NXT S/WV IS RIGHT
ON IT`S HEELS WHICH MAY SPREAD MORE LGT SNOW ACRS THE RGN LATER
IN THE AFTN. ATTM...WE ARE ANTICIPATING ACCUMS IN THE 2-4 INCH RNG
WITH THIS SYSTEM. WILL HAVE TO MONITOR 2NDRY CYCLOGENESIS OFF THE
JERSEY CST WHICH COULD BUMP UP AMTS A BIT ACRS THE CATSKILLS AND
POCONOS.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
XPCT SCT -SHSN TO PREVAIL ON TUE NGT WITH A SFC TROF IN THE
VCNTY...AIDED BY ANOTHER S/WV. IT APPEARS THAT LES SNOWS WILL DVLP
ON WED AS THE SFC TROF DEPARTS AND FLOW BCMS MORE WRLY. ACTIVITY
SHUD BE FAIRLY SHORT LIVED AS WINDS COME ARND TO THE SW WED EVNG
AS LOW PRES MOVS INTO THE CNTRL GTLAKES.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
UPPER LEVEL PATTERN THROUGH MUCH OF THE EXTENDED FEATURES A
NEGATIVE PNA PATTERN, WRN TROF/ERN RIDGE.
MAINLY DRY WEATHER IS EXPECTED WEDNESDAY NIGHT THROUGH THURSDAY
NIGHT AS SFC HIGH PRES WILL BE OFF THE MID ATLANTIC WITH LOW PRES
MOVING INTO THE UPPER GREAT LAKES. SOUTHWEST FLOW WILL PROVIDE
MODERATING CONDITIONS.
LATTER PART OF THE EXTENDED SHOWS THE MEDIUM RANGE MODELS WITH
SIGNIFICANT DIFFERENCES. FOLLOWED WPC GUIDANCE WHICH FOLLOWS THE
ECMWF. ON FRIDAY, SFC LOW PRES MOVING THROUGH EASTERN CANADA WILL
BRING RAIN SHOWERS FOLLOWED BY MIXED RAIN/SNOW SHOWERS AFTER FROPA
FRIDAY NIGHT. THIS BOUNDARY THEN STALLS JUST SOUTH OF AREA WITH
SEVERAL WAVES MOVING NORTHEAST ALONG BOUNDARY. THIS WILL BRING A
CONTINUATION OF CHC POPS FOR RAIN/SNOW SHOWERS.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
12Z UPDATE...
LAKE SNOWS WILL CONTINUE OFF AND ON THROUGH THE DAY WITH OCNL
MVFR/IFR RESTRICTIONS AT KSYR. EXPECT IFR VSBYS IN BLOWING SNOW
BETWEEN NOW AND 16Z. REMAINDER OF TERMINALS SHOULD BE VFR TODAY
WITH OCNL MVFR RESTRICTION POSSIBLY PASSING THROUGH BUT NOT ENOUGH
CONFIDENCE TO INCLUDE IN TAFS AT THIS TIME.
LIGHT MVFR SNOWS MOVE IN AFTER 10Z FROM THE WEST ON TUESDAY FOR
ALL BUT KRME.
W-NW WINDS AROUND 10-12KTS WILL GUST DURING THE DAY TO AROUND
20KTS. WINDS BCM LGT/VRB OVERNIGHT THEN BECOME SERLY AROUND 5KTS
TOWARD 12Z.
OUTLOOK...
TUESDAY THROUGH WEDNESDAY...RESTRICTIONS POSSIBLE FROM SNOW
SHOWERS.
WEDNESDAY NIGHT THROUGH THURSDAY...BECOMING VFR.
THURSDAY NIGHT AND FRIDAY...RESTRICTIONS POSSIBLE IN RAIN SHOWERS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN
SHORT TERM...
LONG TERM...PVN/RRM
AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1213 AM EST MON DEC 16 2013
.SYNOPSIS...
A COLD WEST FLOW OF AIR CROSSING THE LOWER GREAT LAKES WILL CONTINUE
TO GENERATE LAKE EFFECT SNOWS EAST AND SOUTHEAST OF THE LAKES INTO
MONDAY. A CLIPPER SYSTEM BRINGS ANOTHER GENERAL LIGHT SNOWFALL
MONDAY NIGHT THROUGH TUESDAY NIGHT. TEMPERATURES WILL RISE ABOVE
NORMAL TOWARD THE END OF THE WEEK WITH A CHANCE FOR RAIN FRIDAY
AHEAD OF THE NEXT STORM SYSTEM.
&&
.NEAR TERM /THROUGH TODAY/...
WESTERLY FLOW ACROSS THE LAKES WILL CONTINUE LAKE EFFECT SNOWS
OVERNIGHT. A COLD FRONT DROPPING SOUTH ACROSS LAKE ONTARIO WILL
CROSS SOUTH ACROSS NEW YORK OVERNIGHT WITH WINDS VEERING TO
NORTHWEST. THIS WILL SHIFT THE LAKE BANDS FURTHER SOUTH THROUGH THE
EARLY MORNING.
OFF LAKE ERIE...THE LAKE EFFECT SNOW BAND EXTENDS WEST TO EAST
ACROSS ALONG THE I-86 CORRIDOR AT MIDNIGHT. THE BAND HAS WEAKENED
SOME FROM EARLIER IN THE EVENING BUT SNOW RATES UP TO AN INCH AN
HOUR WILL CONTINUE INTO THE EARLY MORNING HOURS. THE LAKE SNOW
ADVISORY FOR WYOMING HAS BEEN DROPPED AND THE LAKE SNOW WARNINGS FOR
CHAUTAUQUA AND CATTARAUGUS COUNTIES AND THE ADVISORY FOR ALLEGANY HAVE
BEEN EXTENDED THROUGH 15Z. MESOSCALE GUIDANCE INCLUDING THE HRRR AND
RGEM CONTINUE TO SHOW LAKE SNOWS WILL CONTINUING INTO THE EARLY
MORNING HOURS BUT IN A BIT WEAKER STATE AS THE FRONT DROPS SOUTH
SHIFTING THE LAKE BANDS TO A NORTHWEST-SOUTHEAST ORIENTATION.
THE SHORTER FETCH ACROSS THE LAKE WILL BREAK THE BAND INTO WEAKER
MULTI-BANDS WHICH WILL PRODUCE AN ADDITIONAL 3-5 INCHES THROUGH THE
MORNING.
OFF LAKE ONTARIO...A VERY STRONG LONG AXIS PARALLEL LAKE BAND AS OF
MIDNIGHT IS SHOWING SIGNS OF SHIFTING SOUTHWARD AS THE COLD FRONT
BEGINS TO CROSS LAKE ONTARIO. LAKE EFFECT SNOW WARNINGS WERE ADDED
TO JEFFERSON AND LEWIS COUNTIES AS REPORTS OF SNOW RATES EXCEEDING
3-4 INCHES PER HOUR HAVE BEEN OBSERVED BENEATH THE BAND. MESOSCALE
GUIDANCE HERE SUGGESTS THE BAND WILL SLOWLY SHIFT SOUTH SOUTH AS
STEERING WINDS VEER TO NORTHWESTERLY BEHIND THE COLD FRONT SHIFTING
SOUTH OF THE LAKE. THE BAND WILL DRIFT SOUTH THROUGH 10Z THEN RUN
ALONG THE SOUTHEASTERN LAKE ONTARIO SHORELINE THROUGH THE REMAINDER
OF THE NIGHT. THE HIGHER QPF IS EXPECTED ACROSS OSWEGO COUNTY
THROUGH THE EVENT SO A WARNING REMAINS HERE. SNOWFALL RATES OF
ONE-TWO OR MORE INCHES PER HOUR CAN BRING 7-14 INCHES OF SNOW
POSSIBLY OVERNIGHT. ONCE THE BAND BECOMES MORE NORTHWEST-SOUTHEAST
ORIENTED THEN LAKE SNOWS WILL BEGIN TO ACCUMULATE ACROSS NORTHERN
CAYUGA AND WAYNE COUNTIES TOWARD EARLY MONDAY MORNING.
MONDAY...ONGOING WEAKER NORTHWEST FLOW LAKE EFFECT SNOWS IN THE MORNING
SHOULD DECREASE IN INTENSITY WITH DEPLETING MOISTURE PROFILES AND
LOWERING INVERSIONS. NAM BUFKIT PROFILES SHOW INVERSIONS LOWERING
BELOW 10KFT TOWARD 18Z AS WEAK HIGH PRESSURE NOSES DOWN ACROSS THE
LOWER GREAT LAKES. TEMPERATURES WILL REMAIN VERY COLD WITH HIGHS
LIMITED TO THE TEENS ACROSS WNY AND SINGLE DIGITS EAST OF LAKE
ONTARIO. WIND CHILLS UNDER A WEST TO NORTHWEST FLOW WILL RUN A SOLID
10 DEGREES BELOW OBSERVED SURFACE TEMPS. OUTSIDE OF THE LAKE EFFECT
SOME SUNSHINE SHOULD BREAK OUT TOWARD THE AFTERNOON AS THE HIGH
PRESSURE BUILDS OVERHEAD WITH MAINLY DRY BUT COLD CONDITIONS.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
TO START THIS TIME PERIOD LAKE EFFECT SNOW WILL LIKELY BE ONGOING
EAST OF BOTH LAKES. AT THE SURFACE HIGH PRESSURE WILL QUICKLY PASS
ACROSS THE REGION MONDAY NIGHT...AND WHILE WINDS WILL BACK SOME
AHEAD OF THE AREA OF HIGH PRESSURE SENDING LAKE EFFECT SNOW
NORTHWARD...INCREASING WIND SHEAR AND BRIEF PASSAGE OF DRIER AIR
WILL QUICKLY ERODE AWAY THE SNOW BANDS.
THE 12Z OPERATIONAL MODEL RUNS ARE COMING INTO BETTER ALIGNMENT WITH
A STRENGTHENING RIDGE OF HIGH PRESSURE OVER THE WEST...WITH SEVERAL
SHORTWAVES DIVING SOUTHWARD ACROSS THE GREAT LAKES REGION. EACH OF
THESE WAVES OF LOW PRESSURE WILL LIKELY BRING A BURST OF SNOW TO THE
REGION...GENERALLY SEVERAL INCHES TO LOW END ADVISORY LEVEL
SNOWS...WITH THE FIRST WAVE ARRIVING LATER MONDAY NIGHT.
WEAK ISENTROPIC UPGLIDE AHEAD OF THE SHORTWAVE...COMBINED WITH
DIFFLUENT FLOW AHEAD OF THE SHORTWAVE PROMOTING VERTICAL UPLIFT
SHOULD BRING A LIGHT SNOW TO WESTERN NEW YORK OVERNIGHT...AND
REACHING EASTERN ZONES LATE MONDAY NIGHT OR EARLY TUESDAY.
BEHIND THE FIRST SHORTWAVE TROUGH A SHORTWAVE RIDGE WILL CROSS THE
REGION TUESDAY WITH PRECIPITATION CHANCES TRENDING DOWN WITH THE
LOSS OF UPWARD MOTION. HOWEVER THE NEXT SHORTWAVE WILL ARRIVE
TUESDAY NIGHT WITH ANOTHER ROUND OF LIGHT SNOW ACROSS THE REGION.
ON WEDNESDAY NORTHWEST FLOW WILL CONTINUE ALOFT...WHILE HIGH
PRESSURE AT THE SURFACE CENTERED OVER THE TENNESSEE VALLEY WILL BRING
MORE OF A WEST TO EAST FLOW ACROSS THE GREAT LAKES. TEMPERATURES AT
850 HPA WILL BE JUST COLD ENOUGH TO PROMOTE INSTABILITY FOR ANOTHER
ROUND OF LAKE EFFECT SNOWS...WITH THE LAKES NOW COOLED DOWN TO
AROUND +2C ON ERIE AND +3-4C ON LAKE ONTARIO. FALLING LAKE INDUCED
EQUILIBRIUM LEVELS AND LOWERING INVERSION HEIGHTS THROUGH THE DAY
WILL NOT MAKE FOR AN IDEAL LAKE EFFECT SNOW SET UP THAT WE SAW
LAST WEEK. STILL SEVERAL ADDITIONAL INCHES OF SNOW ARE POSSIBLE
THROUGH THE DAY WEDNESDAY...TAPERING OFF WEDNESDAY NIGHT. OUTSIDE
OF THESE LAKE BANDS SOME SUNSHINE IS POSSIBLE.
TEMPERATURES WILL LIKELY REMAIN JUST BELOW NORMAL THROUGH THE TIME
PERIOD...AND NOT AS COLD AS IN PRIOR DAYS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A BRIEF PATTERN CHANGE WILL EVOLVE THIS TIME PERIOD AS A LONG WAVE
TROUGH FLATTENS THE WESTERN US RIDGE. IN RESPONSE DOWNSTREAM A RIDGE
OF HIGH PRESSURE WILL DEVELOP ACROSS THE EAST COAST...THOUGH THE
COLD POLAR LOW DROPPING SOUTHWARD TO HUDSON BAY WILL LIKELY RESTRICT
THE AMPLIFICATION OF THE RIDGE.
THIS WILL BRING SOME WARMING TEMPERATURES TO THE AREA TO START THE
TIME PERIOD. MODELS ARE STILL SHOWING SOME INCONSISTENCIES WITH
THE TIMING OF THE EJECTION OF THE CUT OFF LOW OVER THE DESERT
SOUTHWEST. THIS CUT OFF LOW OVER THE SOUTHWEST WILL EVENTUALLY EJECT
FROM THE SOUTHWEST AND LIKELY INTERACT WITH THE NORTHERN BRANCH OF
THE JET STREAM.
WILL BRING SOME CHANCE POPS ACROSS THE REGION FOR NEXT WEEKEND AS
SHORTWAVES WITHIN THE NORTHERN BRANCH OF THE JET STREAM CROSS THE
AREA. WITH THE 12Z MODELS BACKING OFF ON THE TIMING OF THE EJECTION
OF THE DESERT CUT OFF LOW...A DEEPER LOW POSING A LARGER STORM
SYSTEM MAY NOT REACH THE AREA UNTIL THE BEGINNING OF NEXT WEEK.
&&
.AVIATION /05Z MONDAY THROUGH FRIDAY/...
LAKE EFFECT SNOWS OFF LAKE ERIE IS NOW STEAMING EAST ACROSS THE
SOUTHERN TIER WITH IFR CONDITIONS AT KJHW. LAKE EFFECT WILL CONTINUE
BUT IN AN MUCH WEAKENED STATE THROUGH THE OVERNIGHT EVENTUALLY
TAPERING OFF MONDAY MORNING. NORTH OF THIS LAKE EFFECT VFR IS
ONGOING AND WILL CONTINUE THROUGH MONDAY AT KBUF/KIAG/KROC.
EAST OF LAKE ONTARIO AN INTENSE BAND OF LAKE EFFECT IS OBSERVED
BETWEEN KART AND KSYR. THE NORTHERN EDGE IS IMPACTING KART WITH IFR
CONDITIONS. LATER TONIGHT THIS BAND WILL SHIFT SOUTH TOWARD KSYR AND
KFZY WITH KART BECOMING VFR AGAIN. LAKE SNOWS WILL CONTINUE UNDER A
NORTHWEST FLOW THROUGH MONDAY MORNING THEN BEGIN TO TAPER OFF AS
HIGH PRESSURE BUILD OVERHEAD MONDAY AFTERNOON.
OUTLOOK...
MONDAY NIGHT...MAINLY VFR.
TUESDAY...SNOW SHOWERS LIKELY WITH AREAS OF MVFR/IFR.
WEDNESDAY...MAINLY VFR WITH A CHANCE OF SNOW SHOWERS...EXCEPT LAKE
EFFECT SNOW SHOWERS LIKELY SOUTHEAST OF THE LAKES WITH LOCAL IFR.
THURSDAY AND FRIDAY...MAINLY VFR.
&&
.MARINE...
BRISK WESTERLY WINDS ACROSS THE LAKE IS RESULTING IN A PERIOD OF
HIGH END ADVISORY LEVEL WINDS AND WAVES ON BOTH LAKES TONIGHT
LASTING INTO MONDAY BEFORE HIGH PRESSURE BUILDS OVER THE REGION
ALONG WITH DIMINISHING WINDS. A CLIPPER SYSTEM WILL DROP SOUTH
ACROSS THE LAKES ON TUESDAY. WINDS AND WAVES WILL INCREASE AGAIN
TUESDAY NIGHT INTO WEDNESDAY BEHIND THIS PASSING CLIPPER SYSTEM.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW WARNING UNTIL 5 AM EST EARLY THIS MORNING FOR
NYZ007-008.
LAKE EFFECT SNOW WARNING UNTIL 4 PM EST THIS AFTERNOON FOR
NYZ006.
LAKE EFFECT SNOW ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
NYZ004-005.
LAKE EFFECT SNOW WARNING UNTIL 10 AM EST THIS MORNING FOR
NYZ019-020.
LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR
NYZ021.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR LEZ040-
041.
SMALL CRAFT ADVISORY UNTIL 3 AM EST EARLY THIS MORNING FOR
LEZ020.
SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR
LOZ043>045.
SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
LOZ042.
&&
$$
SYNOPSIS...SMITH
NEAR TERM...SMITH
SHORT TERM...THOMAS
LONG TERM...THOMAS
AVIATION...SMITH
MARINE...SMITH/TMA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
649 AM CST MON DEC 16 2013
.UPDATE...
ISSUED AT 642 AM CST MON DEC 16 2013
UPDATE FOR EARLY MORNING TEMPERATURE TRENDS AND TO INCREASE POPS
NORTH AND EAST THIS AFTERNOON. LATEST TRENDS AND HI-RES MODEL RUNS
INDICATE LITTLE OR NO THREAT FOR FREEZING RAIN/SLEET WITH P-TYPE
EXPECTED TO BE ALL SNOW OR POSSIBLE RAIN/SNOW MIX THIS AFTERNOON
IN LOCATIONS WITH WARMER SURFACE TEMPS. LATEST EARLY MORNING MODEL
RUNS INCLUDING THE 06Z WRF AND 11Z RAP ARE ALSO INSISTENT ON AN
AREA OF LIGHT SNOW TRACKING OVER THE NORTHERN AND EASTERN PORTIONS
OF THE FORECAST AREA THIS AFTERNOON. HAVE INCREASED POPS DURING
THE AFTERNOON. THE LIGHT SNOW MAY ADD TO THE TRAVEL HAZARDS...IN
THE FORM OF BRIEF REDUCED VISIBILITY...AS WINDS GUST TO 35 MPH.
THIS IS IN ADDITION TO THE THREAT OF EXISTING SNOW BLOWING ACROSS
ROADS...MELTING...THEN RE-FREEZING.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CST MON DEC 16 2013
MAIN HIGHLIGHTS WILL BE AREAS OF BLOWING/DRIFTING SNOW WITH ICY
ROADS/BLACK ICE POSSIBLY DEVELOPING MONDAY AFTERNOON NORTH...AND A
SLIGHT CHANCE OF MIXED PRECIPITATION THIS AFTERNOON AS ANOTHER
SHORTWAVE TRAVERSES THROUGH.
THE LATEST WATER VAPOR IMAGERY SHOWS TWO SHORTWAVES OF INTEREST.
THE FIRST WAS LOCATED NEAR LAKE WINNIPEG MOVING SOUTHEAST WITH
TIME. LOCAL AND REGIONAL RADAR WAS SHOWING AN AREA OF LIGHT SNOW
FROM NORTHEAST MONTANA...ACROSS NORTHWEST AND INTO NORTH CENTRAL
NORTH DAKOTA. THIS SHORTWAVE IS ALSO INTERACTING WITH A SURFACE
WARM FRONT LOCATED FROM NEAR SHERWOOD...TO MINOT...AND SOUTH TO
GLEN ULLIN AND THEN SNAKING INTO PIERRE SOUTH DAKOTA. MINOT DUAL
POL RADAR SHOWS SOME POTENTIAL FOR AN ELEVATED MELTING LAYER AND
POSSIBLY MIXED PRECIPITATION. THE RAP13 WAS INDICATING THAT LIGHT
SNOW WOULD MAINLY DOMINATE THE PRECIPITATION BAND WITH THE
POSSIBILITY OF LIGHT FREEZING RAIN ON THE BACK EDGE. WILL CONTINUE
WITH THIS THINKING EARLY THIS MORNING.
THE SECOND SHORTWAVE WAS LOCATED IN EAST CENTRAL ALBERTA...WHICH
IS FORECAST TO SHIFT INTO MOHALL BY 00Z TUESDAY. THE LEFT EXIT
REGION OF A 140KT H3 JET WILL CREATE ENOUGH LIFT TO PRODUCE A
SLIGHT CHC OF MIXED PRECIPITATION FOR THE NORTH THIS AFTERNOON.
MOST TEMPERATURES WILL WARM ABOVE FREEZING FROM WEST TO EAST
TODAY AS THE WARM FRONT CONTINUES TO ADVANCE EAST. THE MAIN ISSUE
THIS AFTERNOON WILL BE BRISK WESTERLY WINDS OF 20 TO 30 MPH
CREATING BLOWING/DRIFTING SNOW ACROSS THE HIGHWAYS WITH POSSIBLE
BLACK ICE FORMING. A SPECIAL WEATHER STATEMENT WAS ISSUED
HIGHLIGHTING THE POTENTIAL FOR BLOWING AND DRIFTING
SNOW...MELTING...AND THEN REFREEZING ACROSS THE NORTH. GIVEN
SUCCESSIVE ROUNDS OF LIGHT SNOW THE LAST FEW DAYS...BRISK
WINDS...AND AFTERNOON TEMPERATURES HOVERING AROUND FREEZING...THIS
AREA WILL BE IN LINE FOR THE BLOWING/DRIFTING/MELTING/REFREEZING
PROCESSES. FARTHER SOUTH AND WEST WHERE TEMPERATURES WILL BE IN
THE UPPER 30S...EXPECT ICY TRAVEL TO DEVELOP TONIGHT ONCE WE FALL
BELOW FREEZING AFTER SUNSET. AFTERNOON HIGHS TODAY WILL RANGE FROM
THE UPPER 20S IN THE TURTLE MOUNTAINS TO THE UPPER 30S WEST.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 315 AM CST MON DEC 16 2013
THE MAIN FORECAST ISSUE IS SNOWFALL AMOUNTS AND COVERAGE WITH THE
MID WEEK STORM.
ON TUESDAY...COLDER AIR WILL BEGIN TO GRADUALLY SAG INTO NORTHEAST
NORTH DAKOTA WITH HIGHS EXPECTED TO ONLY REACH THE TEENS. MILD
WEATHER WILL CONTINUE IN THE SOUTHWEST WITH HIGHS IN THE 30S LIKELY.
MODEL AGREEMENT IS IMPROVING REGARDING THE NORTHERN STREAM TROUGH
THAT WILL IMPACT THE STATE WEDNESDAY NIGHT INTO THURSDAY. THE
SOUTHERN HALF OF THE FORECAST AREA...PARTICULARLY ALONG AND SOUTH OF
THE INTERSTATE 94 CORRIDOR...IS STILL FAVORED FOR THE HIGHER
SNOWFALL AMOUNTS. MODEL QPF GENERALLY RANGES FROM 0.2 TO AROUND 0.3
INCHES. WITH RELATIVELY CONSERVATIVE SNOW TO LIQUID RATIOS NEAR OR
BELOW 20 TO 1...THAT WOULD RESULT IN GENERAL 4 TO 6 INCH SNOWFALL
AMOUNTS. HOWEVER...WITH THE INCREASINGLY COLD THERMAL PROFILE AND
POTENTIAL FOR NARROW BANDS OF ENHANCED LIFT...WE COULD EASILY SEE
PERIODS OF HIGHER RATIOS...WHICH WOULD PUSH SNOWFALL AMOUNTS OVER
WARNING CRITERIA SOME AREAS. PLENTY COULD CHANGE OVER THE NEXT 2 TO
3 DAYS...BUT THE POTENTIAL IS THERE.
VERY COLD AIR WILL ACCOMPANY THE TROUGH WEDNESDAY NIGHT THROUGH
SATURDAY. SOME AREAS...ESPECIALLY THE NORTH...MAY HIT WIND CHILL
ADVISORY CRITERIA WEDNESDAY AND THURSDAY NIGHTS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 642 AM CST MON DEC 16 2013
VFR CIGS/VSBYS CAN BE EXPECTED NEXT 24HR. BKN/OVC CIGS BETWEEN 5KFT
AND 10KFT WITH GUSTY WEST-NORTHWESTERLY WINDS OF 20KT TO 30KT WILL
DOMINATE MOST OF THE AERODROMES. BLOWING/DRIFTING SNOW IS POSSIBLE
BUT NOT EXPECTED TO AFFECT VISIBILITIES BELOW VFR AT THIS TIME. A
VCSH HAS BEEN ADDED TO KISN/KMOT/KJMS MONDAY AFTERNOON AS AN UPPER
LEVEL DISTURBANCE TRACKS ACROSS NORTHERN AND CENTRAL NORTH DAKOTA.
EXPECT SCT CLOUDS TO SKC AFTER 00Z TUESDAY WITH BRISK WINDS OF 15KT
CONTINUING THROUGH 12Z TUESDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/LONG TERM...RP KINNEY
SHORT TERM/AVIATION...KS
AREA FORECAST DISCUSSION...UPDATED
NWS PORTLAND OR
532 AM PST MON DEC 16 2013
.SYNOPSIS...AREAS OF FOG ACROSS THE REGION THIS MORNING. HIGH
PRESSURE WILL BUILD TODAY FOR INCREASING OFFSHORE FLOW...AND
POSSIBLE CLEARING TONIGHT. CLEAR SKIES COMBINED WITH LIGHT WINDS
WILL RESULT IN COOLER TEMPERATURES LATE TONIGHT WITH MORE VALLEY FOG
AND POSSIBLY FREEZING FOG FOR TUESDAY MORNING. A COLDER SYSTEM WILL
BRING RAIN AND MOUNTAIN SNOW TUESDAY NIGHT AND WEDNESDAY. THERE WILL
BE A BREAK IN PRECIPITATION THURSDAY BEFORE A SERIES OF WARMER
SYSTEMS BRING PERIODS OF RAIN AND MOUNTAIN SNOW FRIDAY AND THROUGH
THE WEEKEND.
&&
.UPDATE...FOG HAS LIFTED IN MANY AREAS WARRANTING THE CANCELLATION
OF THE DENSE FOG ADVISORY. THERE WILL BE PATCHY DENSE FOG THROUGH THE
MORNING.
PREVIOUS SHORT TERM DISCUSSION...TODAY THROUGH WEDNESDAY
NIGHT...THE WEAK FRONT AND LOW-LEVEL PRECIPITATION THAT STALLED OVER
THE AREA LAST NIGHT IS DISSIPATING AND PUSHING EASTWARD EARLY THIS
MORNING. SURFACE WINDS ARE EASING OVER THE AREA AND WIDESPREAD FOG
HAS DEVELOPED. VISIBILITIES ARE MOSTLY AROUND A HALF OF A MILE...BUT
SHOULD LOWER TO A QUARTER OF A MILE IN THE NEXT COUPLE OF HOURS AS
THE WINDS CONTINUE TO EASE. THIS FOG WILL LIKELY CONTINUE THROUGH
THE MORNING COMMUTE AND HAVE CONTINUED THE DENSE FOG ADVISORY FOR
THE WILLAMETTE VALLEY AND ALONG THE I-5 CORRIDOR OF THE LOWER
COLUMBIA RIVER. ALTHOUGH NOT CURRENTLY INCLUDED IN THE
ADVISORY...THE COAST WILL ALSO HAVE POCKETS OF DENSE FOG. WILL
MONITOR WEB CAMERAS FOR THE COASTAL FOG AND UPDATE THE FORECAST IF
THE DENSE FOG BECOMES MORE WIDESPREAD.
HIGH PRESSURE ALOFT WILL STRENGTHEN OVER THE AREA TODAY AND HOLD
THROUGH TUESDAY WITH A STRONG SUBSIDENCE INVERSION OVER THE AREA
RESULTING IN WARMER TEMPERATURES FOR THE HIGHER TERRAIN THAN THE
LOWER ELEVATIONS. THE INVERSION WILL ALSO LIMIT MIXING TO THE LOWER
LEVELS AND VALLEY FOG MAY REMAIN INTO THE AFTERNOON. THE HRRR MODEL
FORECASTS FOG WITH VISIBILITIES AT OR BELOW A HALF OF A MILE IN THE
INTERIOR VALLEYS THROUGH 21Z (1 PM). A THERMAL TROUGH WILL DEVELOP
OVER THE COAST TODAY AND WEAK N-NE WINDS SHOULD AID IN THE FOG
CLEARING SOMEWHAT THIS AFTERNOON. HOWEVER...THE NORTHERLY FLOW WILL
PROBABLY CAUSE LEFTOVER LOW CLOUDS TO BANK UP AGAINST THE SOUTH END
OF THE WILLAMETTE VALLEY...LEADING TO A COOL AND CLOUDY CONDITIONS
FOR THE SOUTH VALLEY.
CLEARING IS LIKELY THIS EVENING IN MOST AREAS EXCEPT FOR THE SOUTHERN
WILLAMETTE VALLEY AS PREVIOUSLY DISCUSSED. ANY CLEARING WILL LEAD TO
ENHANCED RADIATION COOLING WITH NEAR FREEZING TEMPERATURES EARLY
TUESDAY MORNING. FOG WILL AGAIN DEVELOP IN THE INTERIOR VALLEYS AS
THE WINDS EASE LATE TONIGHT WITH THE POSSIBILITY FOR AT LEAST SPOTTY
FREEZING FOG TUESDAY MORNING.
WITH LIGHT FLOW AND INCREASING HIGH CLOUDS TUESDAY AHEAD OF AN
APPROACHING FRONT ANY LOW CLOUDS WILL BE STUBBORN AND SLOW TO
DISSIPATE UNDER THE STRONGER INVERSION. WHILE VALLEYS REMAIN IN THE
UPPER 30S AND 40S...FOOTHILLS MAY WARM TO THE MID TO UPPER 50S.
A WEAK COLD FRONT WILL BRING INCREASING CHANCES FOR PRECIPITATION
ACROSS THE NORTH TUESDAY EVENING AND NIGHT. THE FRONT WILL SLOWLY
MOVE SOUTHWARD WITH PRECIPITATION REACHING SOUTHERN AREAS BY
WEDNESDAY AFTERNOON. MODEL SOUNDINGS SHOW THAT THE MOISTURE WILL
AGAIN BE CONFINED TO THE LOWER LEVELS WITH THIS FRONT AND THINK THE
PRECIPITATION WILL BE REALLY LIGHT WITH A MIX OF DRIZZLE AND RAIN.
SNOW LEVELS WILL INITIALLY BE HIGH...ABOVE 6000 FEET.
COLDER AIR BEHIND THE FRONT WILL LOWER SNOW LEVELS DOWN TO AROUND
1500 TO 2000 FEET WEDNESDAY NIGHT. MODELS ARE FORECASTING THAT A
SHORTWAVE TROUGH WILL ENHANCE PRECIPITATION OVER THE CASCADES LATE
WEDNESDAY NIGHT...AND EXPECT A QUICK BURST OF ACCUMULATING SNOW FOR
THE CASCADES AND CASCADE FOOTHILLS. HARTLEY
.LONG TERM...THURSDAY THROUGH SUNDAY...MOUNTAIN SHOWERS WILL DECREASE
THURSDAY MORNING AS THE UPPER RIDGE REASSERTS ITSELF OVER THE PACIFIC
NW...WITH WIDESPREAD FOG ALONG THE COAST AND THE INTERIOR VALLEYS.
THURSDAY WILL BE DRY BUT CLOUDY. MODELS ARE IN BETTER AGREEMENT THAT
THE NEXT FRONT WILL APPROACH FROM THE NORTH THURSDAY NIGHT AND DRAG
PRECIPITATION FROM NORTH TO SOUTH ACROSS THE AREA FRIDAY AND
SATURDAY. ONSHORE WINDS SHOULD RAPIDLY RAISE SNOW LEVELS BEFORE THE
ONSET OF PRECIPITATION AND EXPECT SNOW TO BE LIMITED TO THE CASCADES.
SNOW LEVELS SHOULD RISE ABOVE PASS LEVEL FRIDAY NIGHT. MODELS HINT OF
A DIRTY RIDGE PATTERN THROUGH EARLY NEXT WEEK WITH A SERIES OF WEAK
SYSTEMS RIDING OVER THE RIDGE AND BRINGING PERIODS OF LIGHT RAIN AND
MOUNTAIN SNOW. HARTLEY
&&
.AVIATION...WIDESPREAD LIFR AND IFR CONDITIONS EXIST ACROSS THE
AREA EARLY THIS MORNING. WITH INCREASING...ALBEIT LIGHT...OFFSHORE
FLOW...KONP SHOULD IMPROVE TO VFR THIS MORNING. HOWEVER...IMPROVEMENT
WILL BE SLOWER TO OCCUR FOR THE REST OF THE TAF SITES. THERE IS A
DISTINCT POSSIBILITY THAT SEVERAL OF THE INLAND TAF
SITES...ESPECIALLY KSLE AND KEUG...MAY STAY IFR THROUGH THE FORECAST
PERIOD. HOWEVER...FOR NOW WE WILL CONTINUE THE TREND THAT AT LEAST
SOME MVFR TO EVEN VFR CONDITIONS WILL DEVELOP FOR THE PORTLAND TAF
SITES DURING THE AFTERNOON AS WEAK EASTERLY AND NORTHERLY FLOW HELPS
MIX OUT SOME OF THE LOW LEVEL MOISTURE. WHAT IMPROVEMENT DOES OCCUR
MONDAY AFTERNOON...WILL LIKELY DETERIORATE QUICKLY TO IFR AND LIFR
CONDITIONS TOWARDS 03Z TUESDAY FOR MOST TAF SITES AWAY FROM THE
COLUMBIA RIVER.
KPDX AND APPROACHES...IFR TO LIFR CONDITIONS SHOULD PERSIST UNTIL
APPROXIMATELY 20Z MONDAY. LIGHT EASTERLY FLOW SHOULD ALLOW
CONDITIONS TO IMPROVE TO VFR FOR SEVERAL HOURS THIS AFTERNOON.
VFR CONDITIONS WILL LIKELY DETERIORATE TO LIFR/IFR CONDITIONS
TOWARDS 03-06Z TUESDAY. /NEUMAN
&&
.MARINE...WINDS REMAIN RATHER LIGHT ACROSS THE WATERS EARLY THIS
MORNING WITH THIS TREND CONTINUING THROUGH TUESDAY NIGHT.
HOWEVER...SEAS ARE CURRENTLY IN THE 12-13 FT RANGE. LATEST MODEL
GUIDANCE SUGGESTS THESE WILL DROP BELOW 10 FT TOWARDS MIDDAY.
HOWEVER...WILL KEEP THE SMALL CRAFT FOR SEAS OUT THROUGH 00Z TO
ACCOUNT FOR SOME OF THE UNCERTAINTY.
OTHERWISE...A WEAK FRONT WILL PUSH INTO THE WATERS TUESDAY NIGHT.
MODELS CONTINUE TO SUGGEST POST FRONTAL NORTHWESTERLIES WILL REACH
SMALL CRAFT THRESHOLDS OF 25 TO 30 KT LATE WEDNESDAY. THIS SHOULD
PUSH SEAS BACK UP TOWARDS 10 FT THURSDAY. ANOTHER SYSTEM LOOKS ON TAP
FOR FRIDAY...BUT AT THIS POINT...GALE FORCE OR HIGHER WINDS ARE
NOT ANTICIPATED. /NEUMAN
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR CENTRAL
WILLAMETTE VALLEY-GREATER PORTLAND METRO AREA-LOWER
COLUMBIA-SOUTH WILLAMETTE VALLEY.
WA...DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR GREATER
VANCOUVER AREA.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM PST THIS
AFTERNOON FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
FLORENCE OR OUT 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM
PST THIS AFTERNOON.
&&
$$
MORE WEATHER INFORMATION ONLINE AT..
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS PORTLAND OR
301 AM PST MON DEC 16 2013
.SYNOPSIS...AREAS OF FOG ACROSS THE REGION THIS MORNING WITH PATCHY
DENSE FOG LIKELY DURING THE MORNING COMMUTE. HIGH PRESSURE WILL BUILD
TODAY FOR INCREASING OFFSHORE FLOW...AND POSSIBLE CLEARING TONIGHT.
CLEAR SKIES COMBINED WITH LIGHT WINDS WILL RESULT IN COOLER
TEMPERATURES LATE TONIGHT WITH MORE VALLEY FOG AND POSSIBLY FREEZING
FOG FOR TUESDAY MORNING. A COLDER SYSTEM WILL BRING RAIN
AND MOUNTAIN SNOW TUESDAY NIGHT AND WEDNESDAY. THERE WILL BE A BREAK
IN PRECIPITATION THURSDAY BEFORE A SERIES OF WARMER SYSTEMS BRING
PERIODS OF RAIN AND MOUNTAIN SNOW FRIDAY AND THROUGH THE WEEKEND.
&&
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...THE WEAK FRONT AND
LOW-LEVEL PRECIPITATION THAT STALLED OVER THE AREA LAST NIGHT IS
DISSIPATING AND PUSHING EASTWARD EARLY THIS MORNING. SURFACE WINDS
ARE EASING OVER THE AREA AND WIDESPREAD FOG HAS DEVELOPED.
VISIBILITIES ARE MOSTLY AROUND A HALF OF A MILE...BUT SHOULD LOWER TO
A QUARTER OF A MILE IN THE NEXT COUPLE OF HOURS AS THE WINDS CONTINUE
TO EASE. THIS FOG WILL LIKELY CONTINUE THROUGH THE MORNING COMMUTE
AND HAVE CONTINUED THE DENSE FOG ADVISORY FOR THE WILLAMETTE VALLEY
AND ALONG THE I-5 CORRIDOR OF THE LOWER COLUMBIA RIVER. ALTHOUGH NOT
CURRENTLY INCLUDED IN THE ADVISORY...THE COAST WILL ALSO HAVE POCKETS
OF DENSE FOG. WILL MONITOR WEB CAMERAS FOR THE COASTAL FOG AND UPDATE
THE FORECAST IF THE DENSE FOG BECOMES MORE WIDESPREAD.
HIGH PRESSURE ALOFT WILL STRENGTHEN OVER THE AREA TODAY AND HOLD
THROUGH TUESDAY WITH A STRONG SUBSIDENCE INVERSION OVER THE AREA
RESULTING IN WARMER TEMPERATURES FOR THE HIGHER TERRAIN THAN THE
LOWER ELEVATIONS. THE INVERSION WILL ALSO LIMIT MIXING TO THE LOWER
LEVELS AND VALLEY FOG MAY REMAIN INTO THE AFTERNOON. THE HRRR MODEL
FORECASTS FOG WITH VISIBILITIES AT OR BELOW A HALF OF A MILE IN THE
INTERIOR VALLEYS THROUGH 21Z (1 PM). A THERMAL TROUGH WILL DEVELOP
OVER THE COAST TODAY AND WEAK N-NE WINDS SHOULD AID IN THE FOG
CLEARING SOMEWHAT THIS AFTERNOON. HOWEVER...THE NORTHERLY FLOW WILL
PROBABLY CAUSE LEFTOVER LOW CLOUDS TO BANK UP AGAINST THE SOUTH END
OF THE WILLAMETTE VALLEY...LEADING TO A COOL AND CLOUDY CONDITIONS
FOR THE SOUTH VALLEY.
CLEARING IS LIKELY THIS EVENING IN MOST AREAS EXCEPT FOR THE SOUTHERN
WILLAMETTE VALLEY AS PREVIOUSLY DISCUSSED. ANY CLEARING WILL LEAD TO
ENHANCED RADIATION COOLING WITH NEAR FREEZING TEMPERATURES EARLY
TUESDAY MORNING. FOG WILL AGAIN DEVELOP IN THE INTERIOR VALLEYS AS
THE WINDS EASE LATE TONIGHT WITH THE POSSIBILITY FOR AT LEAST SPOTTY
FREEZING FOG TUESDAY MORNING.
WITH LIGHT FLOW AND INCREASING HIGH CLOUDS TUESDAY AHEAD OF AN
APPROACHING FRONT ANY LOW CLOUDS WILL BE STUBBORN AND SLOW TO
DISSIPATE UNDER THE STRONGER INVERSION. WHILE VALLEYS REMAIN IN THE
UPPER 30S AND 40S...FOOTHILLS MAY WARM TO THE MID TO UPPER 50S.
A WEAK COLD FRONT WILL BRING INCREASING CHANCES FOR PRECIPITATION
ACROSS THE NORTH TUESDAY EVENING AND NIGHT. THE FRONT WILL SLOWLY
MOVE SOUTHWARD WITH PRECIPITATION REACHING SOUTHERN AREAS BY
WEDNESDAY AFTERNOON. MODEL SOUNDINGS SHOW THAT THE MOISTURE WILL
AGAIN BE CONFINED TO THE LOWER LEVELS WITH THIS FRONT AND THINK THE
PRECIPITATION WILL BE REALLY LIGHT WITH A MIX OF DRIZZLE AND RAIN.
SNOW LEVELS WILL INITIALLY BE HIGH...ABOVE 6000 FEET.
COLDER AIR BEHIND THE FRONT WILL LOWER SNOW LEVELS DOWN TO AROUND
1500 TO 2000 FEET WEDNESDAY NIGHT. MODELS ARE FORECASTING THAT A
SHORTWAVE TROUGH WILL ENHANCE PRECIPITATION OVER THE CASCADES LATE
WEDNESDAY NIGHT...AND EXPECT A QUICK BURST OF ACCUMULATING SNOW FOR
THE CASCADES AND CASCADE FOOTHILLS. HARTLEY
.LONG TERM...THURSDAY THROUGH SUNDAY...MOUNTAIN SHOWERS WILL DECREASE
THURSDAY MORNING AS THE UPPER RIDGE REASSERTS ITSELF OVER THE PACIFIC
NW...WITH WIDESPREAD FOG ALONG THE COAST AND THE INTERIOR VALLEYS.
THURSDAY WILL BE DRY BUT CLOUDY. MODELS ARE IN BETTER AGREEMENT THAT
THE NEXT FRONT WILL APPROACH FROM THE NORTH THURSDAY NIGHT AND DRAG
PRECIPITATION FROM NORTH TO SOUTH ACROSS THE AREA FRIDAY AND
SATURDAY. ONSHORE WINDS SHOULD RAPIDLY RAISE SNOW LEVELS BEFORE THE
ONSET OF PRECIPITATION AND EXPECT SNOW TO BE LIMITED TO THE CASCADES.
SNOW LEVELS SHOULD RISE ABOVE PASS LEVEL FRIDAY NIGHT. MODELS HINT OF
A DIRTY RIDGE PATTERN THROUGH EARLY NEXT WEEK WITH A SERIES OF WEAK
SYSTEMS RIDING OVER THE RIDGE AND BRINGING PERIODS OF LIGHT RAIN AND
MOUNTAIN SNOW. HARTLEY
&&
.AVIATION...WIDESPREAD LIFR AND IFR CONDITIONS EXIST ACROSS THE
AREA EARLY THIS MORNING. WITH INCREASING...ALBEIT LIGHT...OFFSHORE
FLOW...KONP SHOULD IMPROVE TO VFR THIS MORNING. HOWEVER...IMPROVEMENT
WILL BE SLOWER TO OCCUR FOR THE REST OF THE TAF SITES. THERE IS A
DISTINCT POSSIBILITY THAT SEVERAL OF THE INLAND TAF
SITES...ESPECIALLY KSLE AND KEUG...MAY STAY IFR THROUGH THE FORECAST
PERIOD. HOWEVER...FOR NOW WE WILL CONTINUE THE TREND THAT AT LEAST
SOME MVFR TO EVEN VFR CONDITIONS WILL DEVELOP FOR THE PORTLAND TAF
SITES DURING THE AFTERNOON AS WEAK EASTERLY AND NORTHERLY FLOW HELPS
MIX OUT SOME OF THE LOW LEVEL MOISTURE. WHAT IMPROVEMENT DOES OCCUR
MONDAY AFTERNOON...WILL LIKELY DETERIORATE QUICKLY TO IFR AND LIFR
CONDITIONS TOWARDS 03Z TUESDAY FOR MOST TAF SITES AWAY FROM THE
COLUMBIA RIVER.
KPDX AND APPROACHES...IFR TO LIFR CONDITIONS SHOULD PERSIST UNTIL
APPROXIMATELY 20Z MONDAY. LIGHT EASTERLY FLOW SHOULD ALLOW
CONDITIONS TO IMPROVE TO VFR FOR SEVERAL HOURS THIS AFTERNOON.
VFR CONDITIONS WILL LIKELY DETERIORATE TO LIFR/IFR CONDITIONS
TOWARDS 03-06Z TUESDAY. /NEUMAN
&&
.MARINE...WINDS REMAIN RATHER LIGHT ACROSS THE WATERS EARLY THIS
MORNING WITH THIS TREND CONTINUING THROUGH TUESDAY NIGHT.
HOWEVER...SEAS ARE CURRENTLY IN THE 12-13 FT RANGE. LATEST MODEL
GUIDANCE SUGGESTS THESE WILL DROP BELOW 10 FT TOWARDS MIDDAY.
HOWEVER...WILL KEEP THE SMALL CRAFT FOR SEAS OUT THROUGH 00Z TO
ACCOUNT FOR SOME OF THE UNCERTAINTY.
OTHERWISE...A WEAK FRONT WILL PUSH INTO THE WATERS TUESDAY NIGHT.
MODELS CONTINUE TO SUGGEST POST FRONTAL NORTHWESTERLIES WILL REACH
SMALL CRAFT THRESHOLDS OF 25 TO 30 KT LATE WEDNESDAY. THIS SHOULD
PUSH SEAS BACK UP TOWARDS 10 FT THURSDAY. ANOTHER SYSTEM LOOKS ON TAP
FOR FRIDAY...BUT AT THIS POINT...GALE FORCE OR HIGHER WINDS ARE
NOT ANTICIPATED. /NEUMAN
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR CENTRAL
WILLAMETTE VALLEY-GREATER PORTLAND METRO AREA-LOWER
COLUMBIA-SOUTH WILLAMETTE VALLEY.
WA...DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR GREATER
VANCOUVER AREA.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM PST THIS
AFTERNOON FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
FLORENCE OR OUT 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM
PST THIS AFTERNOON.
&&
$$
MORE WEATHER INFORMATION ONLINE AT..
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1013 AM EST MON DEC 16 2013
.SYNOPSIS...
A SERIES OF WEAK LOW PRESSURE SYSTEMS WILL TRACK FROM THE
NORTHERN PLAINS THROUGH THE EASTERN UNITED STATES TODAY THROUGH
TUESDAY. HIGH PRESSURE WILL BE OVER THE REGION WEDNESDAY AND
THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
FORECAST ON TRACK WITH LIGHT SNOW CONFINED TO NW GREENBRIER COUNTY
THIS MORNING WITH VERY LITTLE OF SIGNIFICANCE FALLING AS FAR EAST
AS LEWISBURG. ADJUSTED SKY/WIND/T/TD GRIDS PER LATEST
OBS/SATELLITE.
PREVIOUS VALID DISCUSSION AS OF 300 AM EST MONDAY TWO PIECES OF
ENERGY COME THROUGH THE NORTHWEST FLOW TODAY AND TONIGHT. FEATURES
WERE SUBTLE IN THE WATER VAPOR LOOP BUT EACH HAD AN AREA OF DEEPER
MOISTURE. FIRST WAVE ARRIVES EARLY THIS MORNING CROSSING THROUGH
WEST VIRGINIA INTO SOUTHERN PENNSYLVANIA BETWEEN 09Z/4AM AND
18Z/1PM. THE NEXT WAVE WILL BE SLIGHTLY STRONGER AND HAS A SURFACE
COLD FRONT WITH IT. THIS REACHES THE WESTERN COUNTY WARNING AREA
AFTER 06Z/1AM TONIGHT. WILL HAVE BEST PROBABILITY OF PRECIPITATION
AS THESE SHORT WAVES CROSS THROUGH.
BY TONIGHT SURFACE AND LOW LEVEL WINDS BECOME MORE WEST SO UPSLOPE
COMPONENT WILL NOT BE AS FAVORABLE. HIGHEST PROBABILITY WILL REMAIN
OVER NORTHWEST SECTIONS OF GREENBRIER COUNTY.
LEE CIRRUS WAS FORMING FROM NEW JERSEY TO CENTRAL VIRGINIA AT 2AM.
MODELS INDICATED HIGH CLOUDS WILL CONTINUE TO EXPAND EAST OF THE
BLUE RIDGE AND SPREAD FARTHER SOUTH ALONG THE MOUNTAINS.
STAYED CLOSE TO MAV GUIDANCE FOR WINDS AND TEMPERATURES TODAY AND
TONIGHT.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM EST MONDAY...
THE FIRST OF TWO SHORTWAVE TROUGHS WITHIN A LARGER LONGWAVE TROUGH
PATTERN WILL MOVE THROUGH THE REGION TUESDAY MORNING. THE SECOND
WILL CROSS THE AREA TUESDAY EVENING. THE BULK OF THE ASSOCIATED
ENERGY WITH BOTH OF THESE WILL REMAIN NORTH OF THE REGION.
HOWEVER...ENOUGH ASSOCIATED MOISTURE...UPPER LEVEL SUPPORT...AND
STRONG NORTHWEST FLOW UPSLOPING WILL TAKE PLACE TO ALLOW FOR SOME
SNOW SHOWERS ACROSS PARTS OF SOUTHEAST WEST VIRGINIA. MOST OF THE
ACCUMULATING SNOW WILL BE CONFINED TO THE PREFERRED UPSLOPE AREAS OF
WESTERN GREENBRIER COUNTY WV. ONE TO TWO INCHES OF SNOW WILL BE
POSSIBLE IN THIS REGION DURING THIS TIME PERIOD.
MODEL GUIDANCE CONTINUE TO SUGGEST THE FORMATION OF A TIGHT PRESSURE
GRADIENT OVER THE REGION ALONG WITH 850 MB WINDS IN THE 40 TO 50 KT
RANGE. WE WILL STILL FORECAST VERY GUSTY WINDS ACROSS THE MOUNTAINS
FROM LATE TUESDAY THROUGH EARLY WEDNESDAY MORNING. SPEEDS WILL BE
LESS ACROSS THE PIEDMONT...BUT STILL WITH NOTABLE GUSTS. AFTER THIS
TIME...THE WINDS WILL BACK MORE TO THE WEST AND THEN SOUTHWEST AS AN
UPPER RIDGE BUILDS OVER THE OHIO VALLEY. THIS WILL BRING AN END TO
THE UPSLOPE SNOW SHOWERS OVER SE WV AND A TREND TOWARD LESS CLOUD
COVER. SURFACE WINDS WILL BECOME LIGHT AS SURFACE HIGH PRESSURE
BUILDS OVER THE REGION.
BY THURSDAY...THE SURFACE HIGH WILL SHIFT TO THE COAST...THUS
ALLOWING WINDS TO BECOME MORE SOUTHERLY. NO PRECIPITATION IS EXPECTED
ON THURSDAY...BUT CLOUD COVER WILL START TO INCREASE WITH THE
APPROACH OF A DISTURBANCE THROUGH THE MID-MISSISSIPPI VALLEY.
TEMPERATURES WILL BEGIN TO TREND MILDER ON THURSDAY...A TREND THAT
WILL CONTINUE THE WEEKEND.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 253 PM EST SUNDAY...
SOUTHWESTERLY FLOW AND INCREASING HEIGHTS WILL BRING TEMPERATURES
WARMER THAN NORMAL TEMPERATURES ON FRIDAY. SATURDAY TEMPERATURES
COULD ALSO BE WARMER THAN NORMAL...BUT MAY FEEL A LITTLE COOLER
WITH PASSING SHOWERS. A COLD FRONT IS EXPECTED TO PASS OVER THE
REGION ON SUNDAY. THIS FRONT WILL BRING TEMPERATURES BACK TO
SEASONAL LEVELS.
FOR THE MOST PART...MODELS ARE IN FAIRLY GOOD AGREEMENT WITH
TRACKING A COLD FRONT FROM THE CENTRAL PLAINS ON THURSDAY TO THE
EAST COAST ON SUNDAY. MODELS SHOWING WAVES TRACKING ALONG THE FRONT
EACH DAY. AS EACH WAVE PASSES...THE FRONT WILL ADVANCE TO THE EAST.
THE CHANCE FOR SHOWERS WILL INCREASE ACROSS THE MOUNTAINS ON FRIDAY.
POPS INCREASE FOR THE ENTIRE FORECAST AREA ON SATURDAY AS THE FRONT
EDGES CLOSER...BUT WILL KEEP CHANCES BETWEEN 30-40 PERCENT. THE
BETTER CHANCE FOR SHOWERS WILL BE WITH THE FRONTAL PASSAGE ON
SUNDAY.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
AS OF 705 AM EST MONDAY...
SHORT WAVE TRACKING OUT OF THE OHIO VALLEY WILL RESULT IN IFR
CEILINGS ACROSS SOUTHEAST WEST VIRGINIA...ALONG WITH OCCASIONAL
LIGHT SNOW WITH MVFR VISIBILITIES. DOWNSLOPE COMPONENT TO THE
WINDS WILL KEEP KROA/KLYH AND KDAN VFR ALTHOUGH WIDESPREAD MID AND
HIGH CLOUDS ARE EXPECTED. THIS WAVE WILL PASS THROUGH THE AREA BY
EARLY AFTERNOON GIVING A BREAK IN PRECIPITATION TO THE WESTERN
UPSLOPE AREAS. HOWEVER...FOLLOWING THIS FEATURE WINDS MAY BRIEFLY
GUSTS 15 TO 25 KNOTS. HRRR AND LOCAL WRF MODELS SHOWED REASONABLE
TIMING AND LOCATION OF PRECIPITATION THIS MORNING.
ANOTHER SHORT WAVE WILL FOLLOW A SIMILAR PATH TONIGHT...REACHING
THE AREA AROUND MIDNIGHT. THIS WAVE WILL BRING SNOW BACK INTO KBLF
AND KLWB AND WILL PUSH A COLD FRONT THROUGH THE REGION. VERY GUSTY
WINDS ARE EXPECTED ON TUESDAY BEHIND THE FRONT. WIND GUSTS OF 20
TO 40 MPH ARE POSSIBLE.
THE EXTENDED LOOKS TO FEATURE VFR CONDITIONS KROA/KLYH/KDAN BUT
KBCB/KBLF/KLWB WILL BE PERIODICALLY BATTLING UPSLOPE CLOUDS AND
SNOW SHOWERS THROUGH WEDNESDAY. WINDS WILL ALSO BE A CONCERN AT
ALL SITES THROUGH MID-WEEK. HIGH PRESSURE THEN GAINS CONTROL FOR
THE END OF THE WEEK WITH LIGHTER SOUTHWEST WINDS AND VFR
CONDITIONS.
THINGS WILL BE DETERIORATING FOR THE WEEKEND AS NEXT LOW PRESSURE
SYSTEM MOVES IN FROM THE WEST WITH PRECIPITATION AND MVFR OR LOWER
CONDITIONS EXPECTED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/PC
SHORT TERM...DS
LONG TERM...RCS
AVIATION...AMS/PM
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
712 AM EST MON DEC 16 2013
.SYNOPSIS...
A SERIES OF WEAK LOW PRESSURE SYSTEMS WILL TRACK FROM THE
NORTHERN PLAINS THROUGH THE EASTERN UNITED STATES TODAY THROUGH
TUESDAY. HIGH PRESSURE WILL BE OVER THE REGION WEDNESDAY AND
THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM EST MONDAY
TWO PIECES OF ENERGY COME THROUGH THE NORTHWEST FLOW TODAY AND
TONIGHT. FEATURES WERE SUBTLE IN THE WATER VAPOR LOOP BUT EACH HAD
AN AREA OF DEEPER MOISTURE. FIRST WAVE ARRIVES EARLY THIS MORNING
CROSSING THROUGH WEST VIRGINIA INTO SOUTHERN PENNSYLVANIA BETWEEN
09Z/4AM AND 18Z/1PM. THE NEXT WAVE WILL BE SLIGHTLY STRONGER AND
HAS A SURFACE COLD FRONT WITH IT. THIS REACHES THE WESTERN COUNTY
WARNING AREA AFTER 06Z/1AM TONIGHT. WILL HAVE BEST PROBABILITY OF
PRECIPITATION AS THESE SHORT WAVES CROSS THROUGH.
BY TONIGHT SURFACE AND LOW LEVEL WINDS BECOME MORE WEST SO UPSLOPE
COMPONENT WILL NOT BE AS FAVORABLE. HIGHEST PROBABILITY WILL REMAIN
OVER NORTHWEST SECTIONS OF GREENBRIER COUNTY.
LEE CIRRUS WAS FORMING FROM NEW JERSEY TO CENTRAL VIRGINIA AT 2AM.
MODELS INDICATED HIGH CLOUDS WILL CONTINUE TO EXPAND EAST OF THE
BLUE RIDGE AND SPREAD FARTHER SOUTH ALONG THE MOUNTAINS.
STAYED CLOSE TO MAV GUIDANCE FOR WINDS AND TEMPERATURES TODAY AND
TONIGHT.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM EST MONDAY...
THE FIRST OF TWO SHORTWAVE TROUGHS WITHIN A LARGER LONGWAVE TROUGH
PATTERN WILL MOVE THROUGH THE REGION TUESDAY MORNING. THE SECOND
WILL CROSS THE AREA TUESDAY EVENING. THE BULK OF THE ASSOCIATED
ENERGY WITH BOTH OF THESE WILL REMAIN NORTH OF THE REGION.
HOWEVER...ENOUGH ASSOCIATED MOISTURE...UPPER LEVEL SUPPORT...AND
STRONG NORTHWEST FLOW UPSLOPING WILL TAKE PLACE TO ALLOW FOR SOME
SNOW SHOWERS ACROSS PARTS OF SOUTHEAST WEST VIRGINIA. MOST OF THE
ACCUMULATING SNOW WILL BE CONFINED TO THE PREFERRED UPSLOPE AREAS OF
WESTERN GREENBRIER COUNTY WV. ONE TO TWO INCHES OF SNOW WILL BE
POSSIBLE IN THIS REGION DURING THIS TIME PERIOD.
MODEL GUIDANCE CONTINUE TO SUGGEST THE FORMATION OF A TIGHT PRESSURE
GRADIENT OVER THE REGION ALONG WITH 850 MB WINDS IN THE 40 TO 50 KT
RANGE. WE WILL STILL FORECAST VERY GUSTY WINDS ACROSS THE MOUNTAINS
FROM LATE TUESDAY THROUGH EARLY WEDNESDAY MORNING. SPEEDS WILL BE
LESS ACROSS THE PIEDMONT...BUT STILL WITH NOTABLE GUSTS. AFTER THIS
TIME...THE WINDS WILL BACK MORE TO THE WEST AND THEN SOUTHWEST AS AN
UPPER RIDGE BUILDS OVER THE OHIO VALLEY. THIS WILL BRING AN END TO
THE UPSLOPE SNOW SHOWERS OVER SE WV AND A TREND TOWARD LESS CLOUD
COVER. SURFACE WINDS WILL BECOME LIGHT AS SURFACE HIGH PRESSURE
BUILDS OVER THE REGION.
BY THURSDAY...THE SURFACE HIGH WILL SHIFT TO THE COAST...THUS
ALLOWING WINDS TO BECOME MORE SOUTHERLY. NO PRECIPITATION IS EXPECTED
ON THURSDAY...BUT CLOUD COVER WILL START TO INCREASE WITH THE
APPROACH OF A DISTURBANCE THROUGH THE MID-MISSISSIPPI VALLEY.
TEMPERATURES WILL BEGIN TO TREND MILDER ON THURSDAY...A TREND THAT
WILL CONTINUE THE WEEKEND.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 253 PM EST SUNDAY...
SOUTHWESTERLY FLOW AND INCREASING HEIGHTS WILL BRING TEMPERATURES
WARMER THAN NORMAL TEMPERATURES ON FRIDAY. SATURDAY TEMPERATURES
COULD ALSO BE WARMER THAN NORMAL...BUT MAY FEEL A LITTLE COOLER
WITH PASSING SHOWERS. A COLD FRONT IS EXPECTED TO PASS OVER THE
REGION ON SUNDAY. THIS FRONT WILL BRING TEMPERATURES BACK TO
SEASONAL LEVELS.
FOR THE MOST PART...MODELS ARE IN FAIRLY GOOD AGREEMENT WITH
TRACKING A COLD FRONT FROM THE CENTRAL PLAINS ON THURSDAY TO THE
EAST COAST ON SUNDAY. MODELS SHOWING WAVES TRACKING ALONG THE FRONT
EACH DAY. AS EACH WAVE PASSES...THE FRONT WILL ADVANCE TO THE EAST.
THE CHANCE FOR SHOWERS WILL INCREASE ACROSS THE MOUNTAINS ON FRIDAY.
POPS INCREASE FOR THE ENTIRE FORECAST AREA ON SATURDAY AS THE FRONT
EDGES CLOSER...BUT WILL KEEP CHANCES BETWEEN 30-40 PERCENT. THE
BETTER CHANCE FOR SHOWERS WILL BE WITH THE FRONTAL PASSAGE ON
SUNDAY.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AS OF 705 AM EST MONDAY...
SHORT WAVE TRACKING OUT OF THE OHIO VALLEY WILL RESULT IN IFR
CEILINGS ACROSS SOUTHEAST WEST VIRGINIA...ALONG WITH OCCASIONAL
LIGHT SNOW WITH MVFR VISIBILITIES. DOWNSLOPE COMPONENT TO THE
WINDS WILL KEEP KROA/KLYH AND KDAN VFR ALTHOUGH WIDESPREAD MID AND
HIGH CLOUDS ARE EXPECTED. THIS WAVE WILL PASS THROUGH THE AREA BY
EARLY AFTERNOON GIVING A BREAK IN PRECIPITATION TO THE WESTERN
UPSLOPE AREAS. HOWEVER...FOLLOWING THIS FEATURE WINDS MAY BRIEFLY
GUSTS 15 TO 25 KNOTS. HRRR AND LOCAL WRF MODELS SHOWED REASONABLE
TIMING AND LOCATION OF PRECIPITATION THIS MORNING.
ANOTHER SHORT WAVE WILL FOLLOW A SIMILAR PATH TONIGHT...REACHING
THE AREA AROUND MIDNIGHT. THIS WAVE WILL BRING SNOW BACK INTO KBLF
AND KLWB AND WILL PUSH A COLD FRONT THROUGH THE REGION. VERY GUSTY
WINDS ARE EXPECTED ON TUESDAY BEHIND THE FRONT. WIND GUSTS OF 20
TO 40 MPH ARE POSSIBLE.
THE EXTENDED LOOKS TO FEATURE VFR CONDITIONS KROA/KLYH/KDAN BUT
KBCB/KBLF/KLWB WILL BE PERIODICALLY BATTLING UPSLOPE CLOUDS AND
SNOW SHOWERS THROUGH WEDNESDAY. WINDS WILL ALSO BE A CONCERN AT
ALL SITES THROUGH MID-WEEK. HIGH PRESSURE THEN GAINS CONTROL FOR
THE END OF THE WEEK WITH LIGHTER SOUTHWEST WINDS AND VFR
CONDITIONS.
THINGS WILL BE DETERIORATING FOR THE WEEKEND AS NEXT LOW PRESSURE
SYSTEM MOVES IN FROM THE WEST WITH PRECIPITATION AND MVFR OR LOWER
CONDITIONS EXPECTED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...DS
LONG TERM...RCS
AVIATION...AMS/PM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
602 AM CST MON DEC 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 329 AM CST MON DEC 16 2013
MONITORING DYNAMIC SYSTEM NEAR LAKE WINNIPEG AND THE RADAR BAND
DEVELOPING ACROSS ND AT 08Z. OTHER RADAR ECHO AND SOME SCT REPORTS
OF SN- BEING REPORTED ALONG WARM ADVECTION ARM EXTENDING THROUGH
THE EASTERN DAKOTAS AND INTO THE MN RIVER VALLEY. THIS SYSTEM WAS
HANDLED WELL AND FEW CHANGES WERE MADE TO THE ONGOING FORECAST
FOR TODAY EXCEPT FOR TIMING.
STRONG CIRCULATION CLEARLY SEEN IN GOES WATER VAPOR IMAGERY NEAR
LAKE WINNIPEG AND THIS SYSTEM AND ITS POTENTIAL VORTICITY
ADVECTION WILL DIG TOWARD LAKE SUPERIOR AND DRAG GOOD DYNAMICS
ACROSS NORTHERN WI TODAY. THIS POTENTIAL VORTICITY ADVECTION...IN
COMBINATION WITH WARM ADVECTION ALONG THE THERMAL RIBBON FROM
700-900 MB...AND SOME MODERATE 250MB JET EXIT REGION DIVERGENCE WILL
PRODUCE A SWATH OF 1-2 SNOW TODAY. HRRR TRENDS SHOW A SOMEWHAT
NARROW BAND SHIFTING ACROSS WI DURING THE DAY...WITH ABOUT 2
HOURS OF SNOW AT ANY ONE POINT. HI-RES WINDOWS FROM NCEP NMM/ARW
16.00Z RUNS SUGGEST SIMILAR TIMING TODAY AND INTENSITY...BUT MAYBEA
BIT WIDER BAND.
A BREAK OCCURS LATE TODAY AND THIS EVENING...BUT HAVE INCREASED
THE SNOW CHANCES TONIGHT WITH ANOTHER 1-2 INCHES NOW EXPECTED
ALONG AND NORTH OF I-90. SECONDARY SHORTWAVE TROUGH RIDING ON THE
NOSE OF THE POLAR JET WILL COME ACROSS THE AREA TONIGHT...A DIRECT
HIT. SO...SNOWFALL SHOULD BREAK OUT AGAIN ALONG AND NORTH OF I-90
AROUND MIDNIGHT...WITH AREAS SOUTH A BIT MORE LIMITED IN THEIR
SATURATION. THE ENERGY WILL SHIFT EAST BY SUNRISE. MODEL GUIDANCE
HAS SOME SPREAD ON THE LOCATION OF THE SNOW WITH SOME SOLUTIONS
FURTHER SOUTH...BUT IT SEEMS THE TRACK OF THE WAVE AND THE JET
FLOW ALOFT WOULD SHOW PREFERENCE TO THE I-90 CORRIDOR AND NORTH.
NEW SNOW TOTALS BY TUESDAY MORNING WILL BE IN THE 1-3 INCH RANGE
WITH THE 3 INCH TOTALS MOST LIKELY ALONG AND NORTH OF I-94. HAVE
COLLABORATED WITH SURROUNDING NWS OFFICES AND WILL HOLD OFF ON THE
ADVISORY AS THE TWO SYSTEMS SHOULD BE SPACED IN TIME...AND THE 3
INCH TOTALS SHOULD BE THE HIGHER END RATHER THAN THE RULE. WILL
COVER IT IN THE HAZ WEATHER OUTLOOK AND POSSIBLY A SPECIAL
STATEMENT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 329 AM CST MON DEC 16 2013
TUESDAY LOOKS TO BE A BREEZY DAY BEHIND THIS WAVE...IN THE 15-25
MPH RANGE. THEN...RIDGE BUILDING STARTS WITH MAINLY SUNSHINE
EXCEPT ACROSS THE NORTH WHERE THE STORM TRACK SHIFT TO. A STRONG
SHORTWAVE TRAVELS ALONG THE U.S. CANADA BORDER AND MORE WARM
ADVECTION IS EXPECTED TUESDAY NIGHT AND WEDNESDAY NIGHT...WITH
PRECIPITATION STILL OFF TO THE NORTH.
THURSDAY-SUNDAY...
SIGNALS CONTINUE IN THE MODEL GUIDANCE FOR PRECIPITATION TO
SPREAD IN LATE THURSDAY AND THURSDAY NIGHT WITH THE FIRST
SHORTWAVE TROUGH EJECTION FROM THE LONGWAVE DEVELOPING ACROSS THE
WRN CONUS. THE SIGNAL IS REMAINING CONSISTENT WITH THE GFS AND GFS
ENSEMBLES STILL THE COLDER SOLUTIONS...WITH THE FRONTAL BOUNDARY
REMAINING THROUGH IL AND THE SOUTHERN FORECAST AREA IN SUB-ZERO
SURFACE TEMPERATURES. ACROSS ABOUT THE SOUTHERN TWO-THIRDS...THE
LIFT APPEARS LIMITED WITH ABUNDANT MOISTURE IN THE 0-3KM
LAYER...BUT NOT ABOVE IN THE ICE PRODUCING LAYER. THUS THE GFS HAS
A 3KM DEEP SUPERCOOLED LIQUID LAYER...CONSISTENT OVER THE PAST
RUNS. THIS IS A FZDZ/FZRA SITUATION AND HOLD THE POTENTIAL FOR
ICING. THE WARMER SOLUTIONS OF THE ECMWF/CANADIAN MODELS WOULD
CAUSE RAIN IN THE SOUTH. THE SPREAD IN THE TEMPERATURE PROFILE IS
STILL VERY LARGE THURSDAY/THU NIGHT AMONG THE WARM VERSUS COLD
SOLUTIONS...WITH SURFACE HIGHS 28F IN THE GFS THURSDAY...AND 45F
IN THE CANADIAN MODEL...WITH THE 16.00Z ECMWF IN THE MIDDLE. THAT
IS WHERE OUR FORECAST TEMPERATURES REMAIN...THUS A MORE LIMITED
ICING AREA IN NERN IA AND SWRN WI...AND AMOUNTS HAVE TRENDED
LOWER...LESS THAN 0.10 INCHES.
TO THE NORTH ON THURSDAY NIGHT IT APPEARS THE NORTHERN STREAM WAVE
WILL PROVIDE ENOUGH FORCING FOR DEEP SATURATION AND LIGHT SNOWFALL
THAT WOULD ACCUMULATE AROUND AN INCH. CURRENT FORECAST HAS THIS
LIQUID VERSUS SNOW OUTCOME ALONG A KMCW-KISW LINE...WITH SNOW
NORTHWEST. OVERALL...DID RAISE PRECIPITATION CHANCES BUT OVERALL
CHANGES WERE MINOR WITH THAT SYSTEM.
THE LONGWAVE TROUGH DIGS DEEPLY INTO MEXICO ON THE WEEKEND AND THERE
IS HIGH SPREAD ON THE OUTCOMES FOR THIS MAJOR ENERGY. THERE WILL BE
MAJOR WINTER WEATHER WITH THIS SYSTEM...BUT THE FURTHER SOUTH IT
DIGS...THE MORE THE AREA WOULD SEEM TO REMAIN UNDER THE NRN
STREAM OF ENERGY AND NOT BE AFFECTED. HAVE SMALL CHANCES OF
PRECIPITATION IN THE FORECAST FOR NOW MAINLY FOR E/SE AREAS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 602 AM CST MON DEC 16 2013
A COUPLE OF WEAK DISTURBANCES WILL BRING TWO ROUNDS LIGHT SNOW
TO THE TAF SITES WITH IFR CONDITIONS EXPECTED. THE FIRST ROUND
WILL MOVE INTO KRST AROUND 14Z...THEN INTO KLSE AROUND 15Z...WITH
VISIBILITIES FALLING TO 1.5 MILES AND CEILINGS LOWERING INTO THE
800 TO 1KFT RANGE. THIS FIRST ROUND OF SNOW SHOULD EXIT THE AREA
BY LATE THIS AFTERNOON WITH CONDITIONS IMPROVING TO VFR. THE
SECOND ROUND OF LIGHT SNOW MOVES IN AFTER MIDNIGHT TONIGHT WITH
IFR CONDITIONS EXPECTED ONCE AGAIN. PLAN ON TOTAL SNOW
ACCUMULATIONS OF AROUND 1 INCH AT KRST AND AROUND 2 INCHES AT
KLSE. THE SECOND ROUND OF SNOW WILL TAPER OFF AFTER 12Z WITH VFR
CONDITIONS RETURNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
339 PM MST MON DEC 16 2013
.SHORT TERM...MODERATE NORTHWEST FLOW ALOFT CURRENTLY OVER THE
REGION WITH MID LEVEL JET STREAK MOVING INTO WESTERN WYOMING.
COMBINATION OF MIXING AND WEAK MOUNTAIN WAVE KEEPING GUSTY WINDS
GOING ACROSS HIGHER MOUNTAINS AND ALONG FOOTHILLS. ALSO A WEAK
INVERSION AT MOUNTAIN TOP...THOUGH IT SEEMS IT`S BEING OFFSET BY
SOME COLDER AIR AT MID LEVELS. THE MIXING HELPED SPREAD WINDS
FURTHER EAST ACROSS URBAN CORRIDOR. SOME GUSTS AROUND 55 MPH WERE
OBSERVED IN THE FAVORED TERRAIN. JET STREAK EXPECTED TO MOVE JUST
NORTHEAST OF THE AREA DURING THE EVENING...WITH INCREASED
SUBSIDENCE BY MIDNIGHT. CROSS SECTIONS SHOWING SOME MID LEVEL
WARMING BEHIND THE JET STREAK WHICH SHOULD INCREASE THE MOUNTAIN
TOP INVERSION AND ENHANCE THE MOUNTAIN WAVE. LATEST RAP CROSS
SECTIONS SHOW THE CROSS MOUNTAIN FLOW INCREASING TO AROUND 40 KTS
NEAR MOUNTAIN TOP AFTER MIDNIGHT. THUS...SHOULD SEE WINDS INCREASE
ACROSS THE MOUNTAINS AND FOOTHILLS OVERNIGHT. LATEST MODEL
GUIDANCE STILL INDICATING THE STRONGER WINDS IN THE MID AND UPPER
SLOPES OF THE NORTHERN FOOTHILLS...AND SEEMS REASONABLE BASED ON
THE NORTHWEST FLOW ALOFT. SPEEDS TO STAY BELOW HIGH WIND CRITERIA.
POTENTIAL FOR OCCASIONAL WESTERLY WINDS SPREADING ONTO THE
ADJACENT PLAINS. DID INCREASE THE WINDS SLIGHTLY ALONG THE BASE OF
THE FOOTHILLS OVERNIGHT. INCREASED OVERNIGHT TEMPERATURES A FEW
MORE DEGREES...ESPECIALLY IN AND NEAR FOOTHILLS WHERE DOWNSLOPE
WINDS WILL KEEP TEMPERATURES FAIRLY MILD. ON TUESDAY...FLOW ALOFT
BECOMES A BIT MORE WESTERLY AND DECREASES SLIGHTLY. THERE IS SOME
WEAK DOWNWARD MOTION...WITH WEAKENING SUBSIDENCE. BUT MIXING IS
EXPECTED BY AFTERNOON WHICH WILL HELP KEEP SOME GUSTY WINDS GOING
IN AND NEAR FOOTHILLS. ACROSS PLAINS...WEAK SURFACE GRADIENT WILL
ALLOW FOR WINDS TO BE LIGHT AND TREND TOWARD DIURNAL TRENDS.
TEMPERATURES ACROSS PLAINS TO BE SLIGHTLY COOLER DUE TO LESS
DOWNSLOPE FLOW...STILL SHOULD WARM CLOSE TO 60 DEGREES.
.LONG TERM...FLOW ALOFT WILL FLATTEN AND BECOME WESTERLY TUESDAY
NIGHT AND WEDNESDAY AS AN UPPER LEVEL TROUGH MOVES OVER THE PACIFIC
NORTHWEST AND KNOCKS DOWN THE RIDGE OVER THE WESTERN STATES. AIRMASS
WILL REMAIN WARM UNDER THE WESTERLY FLOW WITH HIGHS IN THE 60S.
MOISTURE AT THE UPPER LEVELS WILL INCREASE...SO EXPECT HIGH CLOUDS
TO INCREASE AND COULD HOLD BACK TEMPERATURES SOME IF THICK WAVE
CLOUDS FORM. RECORD HIGH FOR WEDNESDAY IS 66 AND COULD BE BROKEN IF
ENOUGH SUNSHINE PREVAILS.
A WEAK SHORT WAVE TROUGH WILL MOVE ACROSS THE STATE WEDNESDAY NIGHT
AS FLOW ALOFT BACKS TO THE SOUTHWEST. WILL HAVE LOW POPS IN THE
MOUNTAINS FOR THIS. ELSEWHERE JUST EXPECTED AN INCREASE IN CLOUDS.
TEMPERATURES WILL REMAIN MILD WEDNESDAY NIGHT WITH LOWS ABOVE
FREEZING MOST LOCATIONS.
COLD FRONT WILL MOVE ACROSS NORTHEAST COLORADO THURSDAY MORNING.
HIGHS WILL BE REACHED EARLY IN THE DAY AND EXPECT TEMPERATURES TO
FALL DURING THE AFTERNOON HOURS. THE COLD AIRMASS IS SHALLOW SO DO
NOT EXPECT MUCH IF ANY PRECIPITATION TO FORM DUE TO UPSLOPE
WINDS. MODELS SHOWING A BAND OF PRECIPITATION FORMING OVER
NORTHWEST COLORADO AND INTO WYOMING DUE TO THE JET. THE NORTH
CENTRAL MOUNTAINS WILL HAVE A GOOD CHANCE AT SEEING SOME OF THE
SNOW...BUT ELSEWHERE CHANCES ARE LOW. THE SNOW THAT DOES FALL IS
EXPECTED TO BE LIGHT.
MAIN LOW DIVES SOUTH AND CUTS OFF OVER NORTHERN MEXICO AND THE MAIN
JET STAYS TO OUR NORTH LEAVING THE AREA UNDER A WEAK FLOW ALOFT
FRIDAY AND SATURDAY. THERE WILL BE ANOTHER CHANCE/SLIGHT CHANCE OF
SNOW AS THE TROUGH AXIS MOVE ACROSS COLORADO SATURDAY. THOUGH IF ANY
SNOW FORMS IT WILL BE LIGHT. THE MOUNTAINS WILL HAVE THE BEST CHANCE
FOR SNOW DUE TO OROGRAPHIC LIFT. TEMPERATURES WILL BE COOL FRIDAY
AND SATURDAY WITH HIGHS IN THE 30S OVER NORTHEAST COLORADO.
NORTHWEST FLOW ALOFT WILL PREVAIL SUNDAY AND MONDAY AS THE MAIN
TROUGH SHIFTS EAST OF COLORADO AND A RIDGE DEVELOPS ALONG THE WEST
COAST. TEMPERATURES WILL WARM A LITTLE SUNDAY AND MONDAY. MAY BE
ENOUGH MOISTURE EMBEDDED IN THE NORTHWEST FLOW ALOFT TO PRODUCE
LIGHT SNOW AT TIMES ALONG AND WEST OF THE CONTINENTAL DIVIDE.
&&
.AVIATION...
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....MEIER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1009 AM MST MON DEC 16 2013
.UPDATE...
&&
.SHORT TERM...WINDS BEEN A BIT GUSTY IN AND NEAR FOOTHILLS DUE
TO MIXING AND SUBSIDENCE WITH NORTHWEST FLOW ALOFT. SOUNDINGS
INDICATING PERSISTENT MOUNTAIN TOP INVERSION. JET STREAK CURRENTLY
MOVING ACROSS WYOMING HELPING WITH SUBSIDENCE OVER COLORADO. THERE
MAY BE SOME DECREASE IN THE WINDS THIS AFTERNOON AS A BIT OF COLD
AIR ADVECTION WEAKENS THE INVERSION. CURRENT WIND FORECASTS SEEM
REASONABLE FOR NOW...BUT WILL INCLUDE A BIT MORE WIND TO URBAN
CORRIDOR FOR THIS AFTERNOON BASED ON CURRENT OBSERVATIONS AND
EXPECTED MIXING. MOUNTAIN WAVE MAY BE AMPLIFIED OVERNIGHT WITH
SOME WARM AIR ADVECTION...WITH POTENTIAL FOR STRONGER WIND GUSTS.
NO WIND HILITIES EXPECTED AT THIS TIME...SPEEDS SHOULD REMAIN
BELOW CRITERIA.
.AVIATION...NORTHWEST WINDS OCCURRING ACROSS AREA AIRPORTS...WOULD
EXPECT THIS TREND TO CONTINUE THROUGH THE AFTERNOON AS NORTHWEST
WINDS ALOFT CONTINUE TO MIX TO THE SURFACE. THE RAP AND HRRR DO
INDICATE WEAK ANTICYCLONE DEVELOPING NORTH OF DENVER DURING THE
AFTERNOON...WITH LIGHT NORTHEAST WINDS AT KDEN. FEEL THIS WILL BE
SHORT LIVED DUE TO THE EXPECTED MIXING. WILL CONTINUE TREND OF
CURRENT TAFS.
&&
.PREV DISCUSSION... /ISSUED 423 AM MST MON DEC 16 2013/
SHORT TERM...NORTHWESTERLY FLOW ALOFT WILL CONTINUE OVER COLORADO
TODAY. MODELS HAVE STRUGGLED A BIT WITH THE LITTLE RIPPLES IN THE
FLOW...AND HAVE TRIED TO DECREASE THE WINDS A BIT TOO QUICKLY.
SUSPECT THIS WILL STILL BE THE CASE TODAY AS ANOTHER JET STREAK
SLIDES JUST NORTHEAST OF US. THERE IS A LITTLE COLD ADVECTION
ALOFT TODAY...THEN WARM ADVECTION AGAIN BEHIND THE JET STREAK BY
THIS EVENING. THIS SHOULD CREATE A MORE FAVORABLE TEMPERATURE
PROFILE FOR AN AMPLIFIED MOUNTAIN WAVE AGAIN SO DESPITE THE VERY
GRADUAL DECREASING GRADIENT...THERE MAY ACTUALLY BE STRONGER GUSTS
OVERNIGHT. BLENDED IN THE LATEST WIND GUIDANCE WHICH FOCUSES THE
WINDS MORE IN THE MID TO UPPER SLOPES OF THE FRONT RANGE OVERNIGHT
WHICH IS PROBABLY ALRIGHT...BUT THE WINDS WILL PROBABLY ALSO SPILL
INTO THE BOULDER AREA AT TIMES SINCE THE COLD AIR HAS BEEN PRETTY
WELL DISPLACED. I WARMED TEMPERATURES SLIGHTLY IN LIGHT OF THE
CURRENT READINGS...GFS LOOKS TOO WARM BUT NAM SEEMS NOT TO KNOW
THAT THE SURFACE COLD AIR IS GONE. ALSO ADDED A BIT MORE CLOUD
COVER AS WAVE CLOUDS WILL LIKELY COME AND GO.
LONG TERM...MODELS HAVE NORTHWESTERLY FLOW ALOFT BECOMING WEST-
NORTHWESTERLY FROM TUESDAY AT 12Z THROUGH WEDNESDAY AT 12Z. A
FLATTENING UPPER RIDGE AXIS MOVES ACROSS THE CWA ON WEDNESDAY AND
THE FLOW ALOFT BECOMES SOUTHWESTERLY BY WEDNESDAY NIGHT LATE. AT
12Z THURSDAY MORNING...THE MODELS SHOW AN UPPER TROUGH JUST
GETTING INTO THE NORTHWESTERN GREAT BASIN. WEAK DOWNWARD QG
VERTICAL VELOCITY IS PROGGED FOR THE CWA TUESDAY INTO WEDNESDAY.
BY WEDNESDAY AFTERNOON...WEAK UPWARD MOTION IS INDICATED...WHICH
CONTINUES WEDNESDAY NIGHT. THE BOUNDARY LAYER WINDS CONTINUE TO
HAVE A DOWNSLOPING COMPONENT TO THEM TUESDAY INTO MID DAY
WEDNESDAY. NORMAL DIURNAL PATTERNS THEN KICK IN. THE GFS AND
CANADIAN BRING A COLD FRONT INTO THE NORTHEAST BY 12Z THURSDAY
MORNING...THE ECMWF KEEPS SHOWING IT MOVE IN ON THURSDAY. FOR
MOISTURE...IT IS DRY TUESDAY AND TUESDAY NIGHT. THERE IS SOME
UPPER LEVEL MOISTURE PROGGED ON WEDNESDAY...THEN LATE WEDNESDAY
NIGHT...MOISTURE STARTS MOVING INTO THE WESTERN CWA IN EARNEST DUE
TO THE NEXT UPPER TROUGH. THERE IS A TAD OF MEASURABLE
PRECIPITATION OVER THE HIGH MOUNTAINS WEST OF THE DIVIDE BY
THURSDAY MORNING. NO POPS TUESDAY THROUGH WEDNESDAY NIGHT. FOR
TEMPERATURES...TUESDAY`S HIGHS ARE 1-3 C WARM THAN TODAY`S
EXPECTED HIGHS. WEDNESDAY`S HIGHS ARE UP ANOTHER 1-3 C OVER
TUESDAY`S. FOR THE LATER DAYS...THURSDAY THROUGH SUNDAY...MODELS
HAVE WEST-SOUTHWESTERLY FLOW ALOFT ON THURSDAY WITH AN UPPER
TROUGH DEVELOPING OVER THE GREAT BASIN. SOUTHWESTERLY FLOW ALOFT
IS PROGGED FRIDAY WITH THE UPPER TROUGH AXIS OVER WESTERN COLORADO
LATE FRIDAY AFTERNOON. THE UPPER TROUGH AXIS IS NOT PROGGED TO
PUSH EASTWARD ACROSS THE CWA UNTIL SATURDAY AFTERNOON AND NIGHT.
ON SUNDAY...NORTH-NORTHWESTERLY FLOW ALOFT IS PROGGED FOR
COLORADO. THE STORMS AND THE COLD AIR IS NOT SIGNIFICANT ACCORDING
TO THE LATEST RUNS.
AVIATION...VFR THROUGH TONIGHT. WESTERLY WINDS WILL
PREVAIL...WITH GUSTS TO 30 KNOTS AT KBJC AND 20 KNOTS AT
KDEN...PROBABLY LIGHTER AT KAPA. TREND MAY BE A BIT MORE NW
DURING THE DAY...THEN BACK TO MORE SW THIS EVENING. MOUNTAIN WAVE
ACTIVITY TO THE WEST COULD EVEN BRING PERIODS OF S TO SE WINDS
TONIGHT...THOUGH THIS IS UNCERTAIN.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....RJK
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1108 AM CST MON DEC 16 2013
.UPDATE...
1108 AM CST
THE NEXT CLIPPER CONTINUES TO MAKE SOUTHEAST PROGRESS TOWARD THE
AREA. LATEST RADAR MOSAIC SHOWS A BAND OF MODERATE TO HEAVY SNOW
STRETCHING FROM NEAR RICE LAKE WISCONSIN SOUTH JUST EAST OF
ROCHESTER MINNESOTA TO PRAIRIE DU CHIEN WISCONSIN WHICH IS
TRACKING SOUTHEAST. A LOOK AT RECENT OBS FROM UP THIS WAY SHOW
PERIODS OF 1/4SM VSBY WITH ROCHESTER COMING IN WITH ABOUT AN HOUR
AND 20 MINUTES OF VSBY BELOW 1SM. BASED ON TRAJECTORY OF MOVEMENT
THE CURRENT SOUTHERN EDGE OF THE HIGHEST REFLECTIVITY WOULD LIKELY
TRACK JUST NORTH OF A LINE FROM ROCKFORD TO CHICAGO WITH
PERIPHERAL LIGHTER INTENSITY SNOW EXTENDING FURTHER SOUTH ROUGHLY
A STERLING TO RENSSELAER LINE. GOING POPS IN GOOD SHAPE COVERAGE
WISE SO WILL ONLY MAKE MINOR TWEAKS AS WELL AS RAISE VALUES IN THE
FAR NORTHEAST. TIMING STILL LOOKS ON TRACK TO AFFECT RFD EARLY
THIS AFTERNOON AND THE CHICAGO METRO LATE THIS AFTERNOON...WITH
THE PEAK PERIOD IN THE 3 OR 4 TO ABOUT 6 PM TIME FRAME. NEAR TERM
FORECAST GUIDANCE SHOWS A RANGE OF SNOW FALL AMOUNTS AND HAVE VERY
FEW RECENT REPORTS. AREAS A BIT FURTHER UPSTREAM ACROSS FAR
SOUTHERN MINNESOTA DID SHOW AMOUNTS OF 1 TO 1.5 INCHES WHICH SEEMS
REASONABLE AND FALLS IN LINE WITH THE CURRENT FORECAST OF 1 TO
POSSIBLY 2 INCHES ALONG AND NORTH OF THE ROCKFORD TO CHICAGO TO
VALPARAISO LINE WITH A QUICK DROP OFF TO THE SOUTH. THE MAIN ISSUE
MAY BE A NARROWER BAND OF HIGHER INTENSITY SNOW THAN WHAT IS
CURRENTLY OBSERVED UPSTREAM...LEADING TO A SHORTER DURATION WHICH
WOULD THEN ALLOW FOR AMOUNTS OF LESS THAN AN INCH IN THE NORTHERN
AREAS BUT THIS WILL BE MORE OF A NOWCAST DETERMINATION SO WILL
STICK WITH THE 1-2 RANGE WITH HIGHEST AMOUNTS NORTH WITH RATES OF
0.5 TO 0.75 INCHES PER HOUR POSSIBLE.
MDB
//PREV DISCUSSION...
316 AM CST
TODAY...
MAIN CONCERNS FOR TODAY WILL BE ON THE APPROACH OF A CLIPPER SYSTEM
THAT IS CURRENTLY PROGRESSING SOUTHEAST ACROSS THE NORTHERN PLAINS.
IR IMAGERY EARLY THIS MORNING INDICATES A WEAK WAVE OVER
CENTRAL/NORTHERN IL PUSHING EAST INTO NORTHCENTRAL IN. REGIONAL
RADAR AND SFC OBS DEPICT SOME LIGHT SNOW FALLING FROM THIS
WAVE...WITH A HANDFUL OF REPORTING SITES INDICATING REDUCED VSBYS TO
ARND 1SM...INDICATING SOME LIGHT ACCUMS ARE LIKELY TAKING PLACE. THE
BULK OF THE SNOW EARLY THIS MORNING HAS FALLEN SOUTH OF A ROCKFORD
TO OHARE LINE...WITH AN EVEN GREATER FOCUS FROM LASALLE TO EASTERN
WILL COUNTY AND POINTS SOUTH. EXPECT MOST LOCATIONS THAT HAVE SEEN
LGT SNOW TO PICK UP BETWEEN A FEW TENTHS UP TO AND ARND 1" BEFORE
ENDING ARND DAYBREAK. BASED ON IR IMAGERY THE CLEARING LINE WAS
ALREADY PUSHING INTO FAR NORTHWEST IL...AND WILL CONTINUE TO BRING
AN END TO THE MORNING SNOW. TEMPS BRIEFLY WARMED WITH THIS
WAVE...HOWEVER WITH THE CLEARING EXPECTED TO PUSH OVER THESE AREAS
WITHIN THE NEXT COUPLE OF HOURS TEMPS WILL QUICKLY RADIATE INTO THE
SINGLE DIGITS AND POSSIBLY A HANDFUL OF POINTS ACROSS THE FAR
WESTERN CWFA MAY DIP TO BELOW ZERO.
AS PREVIOUSLY NOTED...YET ANOTHER MID-LVL WAVE IS PROGGED TO TAKE
THE EXPRESS TRAIN FROM THE NORTHERN PLAINS TOWARDS SOUTHEAST
WISC/NORTHEAST IL. ESTIMATED TIME OF ARRIVAL APPEARS TO BE BY
MIDDAY...QUICKLY SHIFTING EAST BY MID-AFTERNOON. THE AREAS OF
GREATEST CONCERN ARE NORTH OF A OGLE COUNTY TO KANKAKEE COUNTY
LINE...WITH THE HIGHEST TOTALS FALLING ALONG AND NORTH OF A ROCKFORD
TO CHICAGO LINE. UNFORTUNATELY IT SETS THE STAGE FOR A ROUGH COMMUTE
HOME. GUIDANCE HAS BEEN UNDERDOING THIS WAVE WITH RESPECT TO THE
WEAK ADVECTION AHEAD...IRONICALLY THE GFS HAS HAD A SLIGHTLY BETTER
HANDLE. LOOKING AT BUFR PROFILES VIA THE GFS AND A LITTLE WEDGE OF
3HOURS BETWEEN 20-23Z INDICATES IMPRESSIVE OMEGA (LIFT) INTO THE
FAVORED DGZ. DESPITE THE DGZ NOT BEING VERY THICK...THE EFFICIENCY
OF THIS WAVE WILL LIKELY PRODUCE A BURST OF MODERATE TO HEAVY SNOW
IN THIS TIMEFRAME. COBB OUTPUT USING THE GFS INDICATES HOURLY
SNOWFALL RATES OF 1"/HR WITH A RATIO IN THE UPPER TEENS. THIS
APPEARS TO PUT DOWN A QUICK 1-2" OF SNOWFALL THIS AFTN...AND IF THE
SYSTEM SLOWS...THIS COULD EASILY BECOME 2-3" MAINLY ALONG AND NORTH
OF A ROCKFORD TO CHICAGO LINE.
AS FOR TEMPS TODAY...CONSIDERABLE CLOUD COVER WILL KEEP TEMPS IN
CHECK AND LIKELY TOP OUT IN THE UPR TEENS TO LOW 20S. THE FAR
SOUTHERN CWFA COULD WARM INTO THE MID 20S BY MID/LATE AFTN.
CONFIDENCE IN TEMPS/SNOW...HIGH.
CONFIDENCE IN SNOWFALL TOTALS...HIGH.
TONIGHT...
ON THE HEELS OF THE AFTN MID-LVL CLIPPER PRODUCING SNOW FOR PORTIONS
OF THE CWFA...IT APPEARS MOTHER NATURE HAS INDEED FOLLOWED SUIT WITH
THE GIFT THAT KEEPS ON GIVING...AS YET ANOTHER MID-LVL WAVE IS
POISED TO ARRIVE ACROSS THE UPPER MIDWEST AND INTO THE CWFA LATE
TONIGHT THRU DAYBREAK TUE.
MID-LVL VORT WILL REMAIN OVERHEAD WITH TEMPS ALOFT HOLDING IN THE -6
TO -9 DEG C RANGE. DESPITE CONSIDERABLE CLOUD COVER TONIGHT...TEMPS
SHUD BE ABLE TO RADIATE INTO THE LOW/MID TEENS. THE OVERNIGHT
CLIPPER DOES NOT APPEAR TO BE AS POTENT AS ITS
PREDECESSOR...NONETHELESS IT WILL NOT TAKE MUCH MOISTURE TO EASILY
PRODUCE ANOTHER HALF INCH OF SNOWFALL OVERNIGHT INTO DAYBREAK TUE.
CONFIDENCE IN TEMPS/SNOW...HIGH.
TUESDAY THROUGH WEDNESDAY...
MAIN FEATURE FOR TUE WILL BE THE EVOLVING WEATHER PATTERN...WHICH
WILL BE UNDERGOING SOME CHANGES. THE CHALLENGE WILL BE ON HOW WARM
SFC TEMPS WILL BE...GIVEN THE EXPANSIVE SNOWPACK.
ENSEMBLES INDICATE THE ANOMALOUS RIDGES...ONE ACROSS THE CENTRAL
ATLANTIC AND THE OTHER ACROSS THE EASTERN PACIFIC...WILL BE ON THE
MOVE BY TUE. THIS HAS RECENTLY CREATED A BOTTLENECK WITH THE 500MB
TROUGH PARKED ACROSS THE GREAT LAKES/ONTARIO...BUT WILL BEGIN TO
WEAKEN AND PIVOT EAST THROUGH THE MIDDLE OF THE WEEK.
BY WED GUIDANCE INDICATES THE MID-LVL FLOW WILL FLATTEN OUT...WHICH
ONLY APPEARS TO BE MORE OF A TRANSITIONAL PHASE AS YET ANOTHER HIGH
AMPLITUDE RIDGE IS POISED TO DEVELOP ACROSS THE EASTERN PACIFIC.
SFC RIDGING WILL ENGULF MUCH OF THE SOUTHERN STATES...AND LIKELY
STRETCH NORTH INTO THE CWFA BY TUE AFTN THRU WED. BRINGING A PERIOD
OF DRY WEATHER THRU WED EVE.
THE LARGEST CHALLENGE FOR TUE/WED WILL BE ON HOW WARM TEMPS WILL
ACTUALLY BECOME. AS PREVIOUSLY NOTED ABOUT THE EXPANSIVE
SNOWPACK...GUIDANCE HAS CONTINUED TO STRUGGLE WITH THE SIZE AND
DEPTH OF SNOWPACK...WHICH MOST LIKELY IS CAUSING TEMPS TO BE
MODERATING A LITTLE TOO MUCH FOR WED. FLOW DOES TURN SOUTHWESTERLY
WITH WARMER AIR ADVECTING INTO THE REGION...HOWEVER IT WILL LIKELY
BECOME SOMEWHAT TEMPERED BY THE SNOWPACK. SO A DECENT THERMAL
INVERSION WILL PROB SETUP WED AFTN/EVE. WITH THE WARMER SLOWLY
LIFTING OVERHEAD...COUPLED WITH RISING DEW POINTS...THE SNOWPACK
WILL BEGIN TO MELT. THUS LEADING TO THE DEVELOPMENT OF PATCHY FOG.
AT THIS TIME HAVE COOLED TEMPS A DEG OR TWO FOR WED...SIDING MORE
WITH THE LATEST GFS...WHICH KEEPS TEMPS MAINLY ARND 30. THEN
OVERNIGHT LOWS WILL LIKELY ONLY FALL A FEW DEGREES INTO THE MID/UPR
20S.
CONFIDENCE IN TEMPS...MEDIUM.
THURSDAY THROUGH SATURDAY...
THE SEMI-ZONAL FLOW THAT SETUP FOR WED WILL EVOLVE INTO A
SOUTHWESTERLY FLOW WITH WEAK RIDGING DEVELOPING ACROSS THE EASTERN
CONUS. GUIDANCE HAS CONTINUED IN THE MEDIUM TERM TO PROG A 500MB
VORT MAX SLIDING EAST INTO THE FAR SOUTHWESTERN CONUS THUR. TIMING
HAS SLOWED SLIGHTLY...HOWEVER THE ENERGY ASSOCIATED WITH THIS SYSTEM
WILL LIKELY SPAWN A SFC WAVE SOMEWHERE ALONG THE LEE-SIDE OF THE
ROCKIES NEAR THE OKLAHOMA PAN-HANDLE. THE EC/GFS DIFFER ON THE PATH
OF THIS WAVE BEYOND THUR. THIS WILL LIKELY REMAIN A CHALLENGE AS
NUMERICAL WEATHER MODELS FREQUENTLY STRUGGLE ON THE PLACEMENT OF
BARE GROUND/SNOWPACK...RESULTING IN A SOMEWHAT WOBBLE EFFECT ON THE
PATH A SFC LOW WILL TAKE. AT THIS TIME IT APPEARS FAVORABLE THAT THE
LOW WILL LIFT NORTHEAST ACROSS THE CENTRAL PLAINS TOWARDS THE CWFA
FRI MORNING. WITH THE ABUNDANCE OF WARM AIR ADVECTION ACROSS THE
REGION THUR-FRI...PRECIP WILL LIKELY CHANGE OVER FROM A RAIN/SNOW
MIX AT ONSET TO RAIN. PATCHY FOG WILL ALSO ACCOMPANY THE PRECIP FROM
THE MELTING SNOWPACK.
MAX TEMPS FOR THUR/FRI WILL CONTINUE TO BE A CHALLENGE GIVEN THE
AFOREMENTIONED CONDITIONS...SO HAVE SIDED MORE WITH PREVIOUS
FORECASTS AND KEEPING TEMPS IN THE MID/UPR 30S. ALTHOUGH THIS WILL
ALSO HINGE ON THE TRACK OF THE SFC LOW...WHICH ANY ADJUSTMENTS TO
THE SOUTHEAST WOULD FAVORED COOLER TEMPS AND MAY INTRODUCE
ADDITIONAL P-TYPE CONCERNS.
THEN ENSEMBLES CONTINUE TO POINT TOWARDS A RETURN OF TROUGHING FOR
THE UPPER MIDWEST/GREAT LAKES REGION TOWARDS THE END OF THE WEEK. A
COLD FRONT SHUD PUSH ACROSS THE CWFA FRI...BRINGING TEMPS BACK TO
SEASONAL CONDS.
SAT WILL FEATURE TEMPS HOLDING IN THE UPR 20S/ARND 30. ACROSS THE
WESTERN CONUS THE 500MB TROUGH WILL PIVOT EAST SAT...AND GUIDANCE
CONTINUES TO INDICATE A POTENT SYSTEM EJECTING EAST AND LIFTING
NORTHEAST ACROSS THE TENN/OHIO VALLEY FOR THE WEEKEND.
CONFIDENCE...MEDIUM.
SUNDAY THROUGH FIRST HALF OF CHRISTMAS WEEK...
FOR THE SECOND HALF OF THE WEEKEND INTO EARLY CHRISTMAS
WEEK...ENSEMBLES CONTINUE TO POINT AT A RETURN TO COOL WEATHER FOR
THE REGION. THE EASTERN PACIFIC/WESTERN ATLANTIC MID-LVL RIDGES
RETURN...ALTHOUGH DO NOT APPEAR TO BE AS STRONG. THIS ALLOWS SOME
TROUGHING ACROSS THE GREAT LAKES...WITH PERHAPS A SERIES OF WEAK
WAVES AND SOME LGT SNOW FOR THE END OF THE WEEKEND/EARLY CHRISTMAS
WEEK.
CONFIDENCE...MEDIUM.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* SNOW THIS AFTERNOON AFTER 21Z. A PERIOD OF VIS UNDER A MILE
POSSIBLE IN THE HEAVIER BANDS OF SNOW...BETWEEN 22 AND 00 UTC.
* CIGS MAY FALL TO IFR FOR A PERIOD IN THE AFTN DURING THE SNOW.
* CIGS REMAIN MVFR OVERNIGHT WITH SNOW ENDING IN THE EVENING.
* ANOTHER ROUND OF SNOW EXPECTED BETWEEN 12 AND 16 UTC...WITH LOW
VIS DOWN AROUND 1SM LIKELY.
* STRONG NORTHWESTERLY WINDS ON DEVELOPING AFTER 16 UTC ON TUESDAY.
KJB
//DISCUSSION...UPDATED 18Z...
THERE WILL BE A FAIRLY ACTIVE PERIOD OF WEATHER ACROSS THE TERMINALS
THROUGH THE PERIOD...AS TWO CLIPPER SYSTEMS IMPACT THE AREA.
THE FIRST DISTURBANCE...CURRENTLY DROPPING SOUTHEASTWARD ACROSS
WISCONSIN AND NORTHERN IOWA...IS SUPPORTING A BAND OF MODERATE TO
OCCASIONALLY HEAVY SNOW ACROSS SOUTHEASTERN MN AND ADJACENT AREAS
OF WI AND IA EARLY THIS AFTERNOON. THIS ACTIVITY SHOULD MOVE ACROSS
NORTHERN ILLINOIS BY MID TO LATE AFTERNOON...LIKELY PRODUCING A SHORT
PERIOD OF MODERATE SNOW. SEVERAL SITES UNDER THIS BAND OF SNOW ARE
DROPPING DOWN TO A QUARTER MILE. IT APPEARS SIMILAR CONDITIONS WILL
BE OBSERVED AT MOST OF THE EASTERN TERMINALS AFTER 3 PM THIS
AFTERNOON...WITH THE MOSTLY LIKELY TIME FOR LOW VIS UNDER A MILE
BETWEEN 4 AND 6 PM...AND A HOUR OR TWO SOONER AT KRFD. ANY HEAVY
SNOW BURSTS WOULD LIKELY ONLY LAST UP TO AN HOUR...WITH LIGHTER SNOW
OUTSIDE OF THESE BANDS. CIGS WITHIN THE SNOW WILL ALSO LIKELY FALL
DOWN AROUND OR POSSIBLY JUST BELOW 1,000 FEET AGL FOR BRIEF PERIODS.
THE SNOW WILL ABATE QUICKLY AFTER 7 PM THIS EVENING.
THE NEXT DISTURBANCE ARRIVES FOR EARLY TUESDAY MORNING. THIS SYSTEM
WILL BE VERY SIMILAR TO THE FIRST...WITH ANOTHER DECENT 3 TO 4 HOUR
WINDOW OF SOME MODERATE...TO PERHAPS HEAVY SNOWFALL. THE BEST TIMING
FOR MOST TERMINAL SITES WOULD BE BETWEEN ABOUT 12 UTC AND 16 UTC
TUESDAY MORNING. ONCE THE SNOW ENDS BY LATE MORNING...THE MAIN
CONCERN WILL BE WITH THE WINDS. THE WINDS ARE EXPECTED TO INCREASE
OUT OF THE NORTHWEST BY LATE MORNING. WIND GUSTS IN EXCESS OF 30 KT
APPEAR LIKELY...AND THEY COULD EVEN BE CLOSE TO 35 KT FOR A SHORT
PERIOD EARLY TUESDAY AFTERNOON.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN SNOW FALLING THIS AFTN AND RELATED VSBY AND
CIG HEIGHTS.
* MEDIUM-HIGH CONFIDENCE IN SN TUESDAY MORNING.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
KJB
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT AND WEDNESDAY...VFR.
THURSDAY...CHC OF RA AND SN IN THE MORNING BECOMING ALL RAIN. FOG
IS LIKELY. IFR CIGS.
FRIDAY...CHC RAIN OR SNOW BECOMING ALL SNOW BY THE AFTERNOON. IFR
CIGS PSBL...IMPROVING OVERNIGHT.
SATURDAY...CHC SNOW. MVFR OR LOWER.
SUNDAY...SCHC SNOW IN THE MORNING. MVFR PSBL.
JEE
&&
.MARINE...
403 AM CST
HIGH PRESSURE IS MOVING OVER THE LAKE THIS MORNING WITH WINDS
BECOMING SOUTHWEST THROUGH THE MORNING. WAVES WILL CONTINUE TO
SUBSIDE THEREFORE EXPECTING THE SMALL CRAFT ADVISORY FOR PLACES EAST
OF GARY INDIANA TO END ON TIME THIS MORNING. LOW PRESSURE PASSES TO
THE NORTH TOMORROW AND THE PRESSURE GRADIENT TIGHTENS RESULTING IN
INCREASING WINDS THROUGH TUESDAY. ISSUED A GALE WATCH FOR THE
SOUTHERN HALF OF THE LAKE AND POINTS EAST OF GARY FOR TUESDAY
MORNING THROUGH TUESDAY EVENING. THE OPEN WATERS SEEM LIKE A SLAM
DUNK...BUT CONFIDENCE IS MEDIUM FOR THE INDIANA NEARSHORE WATERS.
REGARDLESS A WATCH IS CERTAINLY VALID. FOR THE ILLINOIS NEARSHORE
WATERS...ISSUED ANOTHER SMALL CRAFT ADVISORY AS WINDS SHOULD TOP OUT
AROUND 30 KT. COULD SEE A FEW GALE FORCE GUSTS TUESDAY
MORNING...BUT NOT ENOUGH TO WARRANT A GALE HEADLINE. WINDS DIMINISH
TUESDAY NIGHT BUT WAVES WILL REMAIN HAZARDOUS OVER NORTHWEST
INDIANA...SO AN ADDITIONAL SMALL CRAFT ADVISORY WILL BE NEEDED.
HIGH PRESSURE PASSES TO OUR SOUTH TUESDAY NIGHT INTO WEDNESDAY AND A
LOW PRESSURE TROUGH APPROACHES FROM THE WEST WEDNESDAY. WINDS TURN
SOUTHWEST AND INCREASE IN SPEED. A SMALL CRAFT ADVISORY MAY BE
NEEDED FOR HIGH WINDS. THE NEXT LOW PRESSURE SYSTEM PASSES OVER THE
LAKE THURSDAY NIGHT WITH WINDS BECOMING NORTHWEST ON ITS BACKSIDE.
HIGH PRESSURE ARRIVES FRIDAY NIGHT WITH LIGHT WINDS EXPECTED AS WE
MOVE INTO THE WEEKEND. YET ANOTHER LOW PRESSURE SYSTEM PUSHES UP
THE OHIO RIVER VALLEY SATURDAY NIGHT INTO SUNDAY WITH WINDS
STRENGTHENING AND BECOMING NORTHWEST.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ744-LMZ745...MIDNIGHT TUESDAY TO 9 AM
TUESDAY.
GALE WATCH...LMZ744-LMZ745...9 AM TUESDAY TO 9 PM TUESDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...MIDNIGHT
TUESDAY TO MIDNIGHT WEDNESDAY.
GALE WATCH...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...5 AM
TUESDAY TO 9 PM TUESDAY.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
1150 AM CST Mon Dec 16 2013
.DISCUSSION...
ISSUED 1000 AM CST Mon Dec 16 2013
Clouds currently blanket most of central Illinois in the wake of
a weak clipper system that tracked through the region overnight.
Trailing frontal boundary stretches from southern Illinois
northwestward into the Dakotas. Immediately north of the
boundary, low clouds and fog persist from near Terre Haute,
Indiana westward to Quincy. With winds expected to remain very
light from the east/northeast until later this afternoon when the
front begins to lift back northward, think clouds will hold firm
across the area. The exception will be across the far southern
KILX CWA around Flora and Lawrenceville where partly to mostly
sunny skies will be observed. Meanwhile, next clipper system is
currently evident on water vapor imagery over northern Minnesota.
This system is bringing light snow to much of Minnesota into
northern Iowa, with its projected trajectory to remain mostly
north of central Illinois today. 12z NAM forecast soundings remain
quite dry and latest HRRR keeps radar echoes further north. Will
therefore only mention a chance for flurries along/north of I-74
this afternoon/evening. Zone update has already been issued.
Barnes
&&
.AVIATION...
ISSUED 1150 AM CST Mon Dec 16 2013
IFR conditions will continue at the I-72 terminals this afternoon
as a stationary frontal boundary remains in the vicinity. Once
weak low pressure tracks into the Great Lakes, light/variable
winds initially will become westerly by early evening. This will
allow ceilings to improve markedly into the VFR category. Based on
timing of clipper system to the north, winds will switch to
westerly at KPIA by 00z then further east at KCMI by 03z. After
that, W/NW winds will prevail through Tuesday morning with
gradually clearing skies.
Barnes
&&
.PREV DISCUSSION...
ISSUED 256 AM CST Mon Dec 16 2013
Weak high pressure over much of the Midwest with northwesterly
flow aloft ushering in a couple of clipper systems in the short
term. Snow coming to an end this morning over ILX, but first
issues with the forecast revolve around the resolution of the next
system moving in later this afternoon/evening. Ridge building in
the SW will eventually result in some moderation of the
temperatures in the region, but existing snow field will counter
the warm up as well. Influence of the snowpack not represented
well in the models. In addition, GFS and ECMWF starting to come
more into line with the next major system next weekend. However,
the details are the fine line with major ramifications to the
thermal profile and resultant precip type.
SHORT TERM...Today and Tomorrow...
Cold and cloudy conditions continue as one clipper pulls away from
the region and another comes in on its heels later this afternoon.
Snow showers should remain mainly to the NE, but considering the
more southerly track of this mornings wave, will keep slight
chance pops in the NE. Little to no accumulations expected and
will keep the QPF low. Temperatures a little under guidance today
as the impact of the snow is not showing up enough in the models.
Another cold overnight, and temperatures begin to moderate with
more westerly flow at the sfc for Tuesday. Still concerned that
the forecast is a couple degrees too high, particularly in the
south. Winds becoming more southwesterly for Tuesday night,
especially after midnight, ushering in warmer air with a bit more
moisture. Moving this RH over a snowpack brings the threat of fog.
However, between the winds staying up just a bit and with the
models having a major issue with the boundary layer, confidence is
low.
LONG TERM...Wednesday through Sunday...
Low confidence continues with the temperatures through the middle
of the week. Will depend greatly on the persistence of the WAA
from the SW and the snow melt. After the main trof pulls to the
east Tues night/Wed, flow eventually moves to a more SWrly pattern
with a trof digging in over the west coast. Deep upper low
becoming briefly cut off in the GFS and ECMWF as the models start
to converge. SWrly flow setting up and putting ILX in a transition
zone temperature wise with the initial passage of the front on
Thurs night/Friday. Front moving into and stalling out just to the
south over the Ohio River Valley. Location of the boundary as a
series of upper waves eject out and along said front will make a
major difference on the forecast. Northerly extent of the precip
with respect to the front is the main issue for the forecast as
well as how deep into the cold air the precip reaches. Latest
ECMWF even pointing to ice, while GFS maintains mostly snow after
a transitional mix. Precip type is still ambiguous, much less QPF
depending on extent of precip with the front stalled to the
south. A series of small waves rippling along the stalled front
keeps high chance pops in the AllBlend for Fri through Sunday and
will leave that as is.
HJS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
ISSUED BY NATIONAL WEATHER SERVICE LA CROSSE WI
302 PM CST MON DEC 16 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 302 PM CST MON DEC 16 2013
MAIN SHORT TERM CONCERN IS ON SNOW POTENTIAL LATE TONIGHT INTO
TUESDAY MORNING.
CURRENTLY AS OF 21Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER THE WESTERN U.S. INTO BRITISH COLUMBIA WHILE
TROUGHING DOMINATED EASTERN CANADA AND IN GENERAL THE EASTERN U.S..
WITHIN THIS TROUGHING...TWO SHORTWAVES WERE NOTED OVER SOUTHERN
MINNESOTA AND IN NORTH DAKOTA. THE SHORTWAVE OVER SOUTHERN MINNESOTA
WAS PRODUCING A BAND OF SNOW ON RADAR MARCHING ACROSS WISCONSIN...
CLIPPING PORTIONS OF NORTHEAST IOWA INTO NORTHERN ILLINOIS. THE
NEXT AREA OF SNOW EXISTS OVER EASTERN MONTANA INTO WESTERN NORTH
DAKOTA...ON THE WEST SIDE OF THE SHORTWAVE THERE. THIS BAND OF
SNOW IS BEING PRODUCED MORE BY MID-LEVEL FRONTOGENESIS AND UPPER
DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A 110-130 KT JET STREAK
IN NORTHEAST MONTANA PER RAP ANALYSIS. CLOSER TO THE FORECAST
AREA...COMBINATION OF LOW SUN ANGLE AND A SURFACE RIDGE OF HIGH
PRESSURE IN PLACE HAS BEEN LIMITING MIXING...KEEPING A STRATUS
DECK IN PLACE FOR MUCH OF THE DAY. THE AIRMASS IS ALSO COOL IN A
SHALLOW LAYER...SINCE 850MB TEMPS RANGE FROM 4C TO -4C SOUTHWEST
TO NORTHEAST ACROSS THE FORECAST AREA. 12Z DVN SOUNDING REALLY
REFLECTS THE SHALLOW COOL LAYER AND THE STRATUS WITH A SATURATED
VERY STRONG INVERSION BETWEEN 925MB AND 825MB.
FOCUS IS ON THE SHORTWAVE COMING OUT OF NORTH DAKOTA...ALONG WITH
THE MID LEVEL FRONTOGENESIS AND UPPER JET STREAK ON ITS WESTERN
SIDE...WHICH ARE PROGGED TO DIG SOUTHEAST TO DUBUQUE BY 12Z TUESDAY.
MODELS ARE IN VERY GOOD AGREEMENT ON ALL OF THE AFOREMENTIONED
FEATURES THUS HAVE FOLLOWED THE CONSENSUS. WE SHOULD SEE A DRY
EVENING AREA WIDE...THEN THE BAND OF SNOW UP IN WESTERN NORTH DAKOTA
WILL ARRIVE GENERALLY TO LOCATIONS ALONG/NORTH OF US-20. RAISED
PRECIPITATION CHANCES UP TO 70 IN THIS AREA...AND EVEN INCLUDED SOME
CHANCES A BIT FARTHER SOUTH TOWARDS BUT NOT TO THE I-80 CORRIDOR IN
THE EVENT THE BAND SLIPS A BIT FARTHER SOUTH. MUCH OF THE SNOW LOOKS
TO BE CONFINED BETWEEN 06-12Z TUESDAY...WITH PERHAPS A LITTLE SNOW
LINGERING IN NORTHWEST ILLINOIS BETWEEN 12-14Z BEFORE IT PUSHES
OFF TO THE EAST. TOTAL SNOW AMOUNTS MAY BE UPWARDS OF 1/2 INCH TO
1 INCH...HIGHEST NEAR DUBUQUE.
OTHER ISSUES OF NOTE IN THE SHORT TERM.
1. WINDS PICKING UP IN THE WAKE OF THE SHORTWAVE PASSAGE. THE
PRESSURE GRADIENT IS PROGGED TO REALLY TIGHTEN UP TUESDAY
MORNING...RESULTING IN WEST TO NORTHWEST SPEEDS OF 15 TO 25 MPH WITH
GUSTS PERHAPS APPROACHING 35 MPH. WINDS DO NOT LOOK TO RELAX UNTIL
LATE IN THE DAY WITH DIURNAL COOLING AND THE APPROACH OF A SURFACE
RIDGE AXIS. THE WINDS COULD BLOW SOME OF THE SNOW AROUND THAT FALLS
TONIGHT INTO TUESDAY MORNING.
2. CLOUDS. THE STRATUS DECK CURRENTLY IN PLACE LOOKS TO CLEAR OUT
THIS EVENING AS WINDS SHIFT WEST...DRAWING DRIER AIR IN OUT OF
NEBRASKA AND WESTERN IOWA. SKIES HAVE BEEN CLEARING IN WESTERN IOWA
ALL DAY REFLECTING THE DRY AIR. CLOUDS SHOULD TEMPORARILY INCREASE
WITH THE APPROACH OF THE NORTH DAKOTA SNOW BAND...THEN DECREASE
AGAIN ON TUESDAY IN ITS WAKE.
3. TEMPERATURES. IF WINDS CAN DECOUPLE THIS EVENING WHEN SKIES ARE
CLEAR...READINGS COULD DIP INTO THE SINGLE DIGITS. CONFIDENCE IS NOT
HIGH ENOUGH TO GO THAT COLD...THUS STAYED CLOSER TOWARDS THE
CONSENSUS. HIGHS DEFINITELY WARMER TOMORROW WITH MORE SUN AND WINDS
FOR MIXING...THOUGH 850MB TEMPS ARE COOLER BETWEEN -8 AND -10C.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 PM CST MON DEC 16 2013
MAIN LONG TERM FORECAST CONCERNS ARE ON PRECIPITATION TYPES
WEDNESDAY NIGHT THROUGH FRIDAY...AND AGAIN SATURDAY INTO SUNDAY.
MODELS REMAIN CONSISTENT IN SHOWING A MAJOR PATTERN CHANGE OVER THE
NEXT FEW DAYS...RESULTING FROM A POTENT TROUGH DIGGING DOWN FROM
NORTHERN BRITISH COLUMBIA AT 00Z WEDNESDAY TO SOUTHERN CALIFORNIA BY
00Z FRIDAY. THIS MODULATES THE PATTERN DOWNSTREAM OVER THE
FORECAST AREA FROM NORTHWEST FLOW ON TUESDAY...TO ZONAL ON
WEDNESDAY...AND FINALLY SOUTHWESTERLY ON THURSDAY. IN RESPONSE TO
THIS PATTERN CHANGE...WARM ADVECTION IS EXPECTED...WITH MOISTURE
ADVECTION COMING INTO PLAY AS WELL ONCE HIGH PRESSURE MOVES OUT OF
THE WAY OF THE GULF OF MEXICO COME WEDNESDAY.
AFTER WHAT WILL BE QUIET WEATHER TUESDAY NIGHT AND WEDNESDAY...
THINGS GET MORE INTERESTING FOR WEDNESDAY NIGHT AND THURSDAY. 16.12Z
NAM/GFS/ECMWF ALL SHOW LOW LEVEL SATURATION TAKING PLACE WEDNESDAY
NIGHT...WITH THE DEPTH OF THE SATURATION GROWING IN TIME THROUGH
THURSDAY. AS HIGHER MOISTURE IMPINGES ON THE COOLER...SNOW PACK OVER
THE AREA...ANTICIPATING AREAS OF FOG TO DEVELOP WEDNESDAY EVENING.
MAY EVENTUALLY NEED A DENSE FOG ADVISORY. IN ADDITION...THERE COULD
EVEN BE SOME DRIZZLE IN THIS FOG WEDNESDAY NIGHT...AS SUGGESTED BY
THE 16.12Z NAM QPF FIELDS...BUT CONFIDENCE IS TOO LOW TO MENTION
PRIOR TO 12Z THURSDAY. BETTER MODEL AGREEMENT AFTER 12Z THURSDAY FOR
DEEPER LOW LEVEL MOISTURE AND THE ISENTROPIC LIFT DOES GRADUALLY
INCREASE. THUS...PRECIPITATION CHANCES INCREASE THROUGH THE DAY
THURSDAY. SOUNDINGS DEPICT NO ICE IN THE CLOUDS...THUS ANY
PRECIPITATION THAT FALLS WILL BE IN LIQUID FORM...WITH THE SURFACE
AND POSSIBLY EVEN GROUND TEMPERATURE DICTATING WHETHER IT FREEZES
ON CONTACT. IT DOES SEEM THAT THE GREATER ICING THREAT WOULD BE
NORTH OF I-80 THURSDAY MORNING...SINCE TEMPERATURES IN MOST PLACES
ALONG/SOUTH OF I-80 MAY STRUGGLE TO FALL BELOW FREEZING WEDNESDAY
NIGHT. A COLD FRONTAL BOUNDARY IS PROGGED TO SLOWLY SLIDE
SOUTHEAST THROUGH THE FORECAST AREA ON THURSDAY...WHICH COMBINED
WITH DAYTIME HEATING SHOULD HELP TO GET RID OF THE FOG.
AS WE HEAD TOWARDS THE WEEKEND...MODELS ARE IN GOOD AGREEMENT
SPLITTING UP THAT WESTERN TROUGH. THE NORTHERN PORTION SHORTWAVE
TROUGH IS PROGGED TO SLIDE ACROSS MN AND WI...WHICH SIMULTANEOUSLYBRINGS
A SURFACE LOW NORTHEAST THROUGH THE FORECAST AREA. PRECIPITATION
SHOULD INTENSIFY SOME AHEAD OF THE SURFACE LOW...ENOUGH TO WARRANT
HIGHER PRECIPITATION CHANCES. THE PRECIPITATION THEN EXITS OFF TO
THE EAST FRIDAY WITH THE PASSAGE OF THE TROUGH. AGAIN...NO ICE IS
SUGGESTED IN THE CLOUDS...MEANING EITHER RAIN OR FREEZING RAIN AT
THE SURFACE DEPENDING ON THE SURFACE TEMPERATURE.
FOCUS THEN SHIFTS TO THE SOUTHERN PORTION OF THE WESTERN
TROUGH...WHICH THE 16.12Z ECMWF/CANADIAN/GFS ALL SHOW LIFTING UP
THROUGH THE CENTRAL PLAINS AND ILLINOIS SATURDAY INTO SUNDAY. WE
NEED TO WATCH THIS SHORTWAVE AND ASSOCIATED SYSTEM CLOSELY FOR
SNOW...SLEET AND FREEZING RAIN. THE THREAT FOR SLEET AND FREEZING
RAIN RIGHT NOW SEEMS TO BE HIGHEST SOUTHEAST OF A LINE FROM ROCK
FALLS TO MOLINE IL AND MT. PLEASANT IA. RAISED PRECIPITATION
CHANCES IN THIS AREA TOO FOR SATURDAY NIGHT TOWARDS 60 AS MODELS
ARE COMING INTO BETTER AGREEMENT. COLDER AND DRIER AIR WILL FILTER
IN BEHIND THIS SYSTEM FOR SUNDAY NIGHT AND MONDAY AS AN ARCTIC
HIGH PRESSURE AREA BUILDS SOUTH INTO THE REGION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1112 AM CST MON DEC 16 2013
LOW STRATUS FIELD STUCK IN INVERSION CONTINUES TO PRODUCE IFR AND
MVFR CEILINGS. IN ADDITION...LATEST SHORT WAVE DROPPING OUT OF
CANADA WAS SWEEPING IN SOME SNOW TO AREAS NORTH OF INTERSTATE 80
WHICH COULD ALSO IMPACT AVIATION MAINLY AT KDBQ AREA. ONCE WAVE
PASSES AND LOW LEVEL WINDS BEGIN TO VEER...EXPECT SOME OF THE
STRATUS TO LIFT ALLOWING FOR MORE VFR CONDITIONS GOING INTO TONIGHT.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...SHEA/ARX
AREA FORECAST DISCUSSION
NWS PADUCAH KY
228 PM CST Mon Dec 16 2013
.SHORT TERM...(This Evening through Wednesday night)
ISSUED AT 228 PM CST MON DEC 16 2013
We have finally gotten rid of the low level moisture and mainly
clear skies are common across the Quad State. This is in stark
contrast to conditions immediately north of our CWA, on the other side
of a frontal boundary, where ceilings are below 1000 ft and
visibilities are restricted and winds are northeasterly. The RAP13
keeps the bulk of the lower level moisture to our north/northeast
throughout the rest of the day. If any low clouds do invade our
area, it would be up in the EVV - tristate region.
The aforementioned boundary to our north is progged to slide south
across the region later today/this evening, as energy aloft to our
northwest travels southeast in the NW flow. Not sure of the amount
of cloudiness that will accompany the frontal passage, as the GFS is
more robust with the low level moisture returning this evening. It
appears as though a secondary boundary moves through the area during
the morning hours on Tuesday and brings another possible wave of
clouds. Not enough moisture in either frontal passage to worry about
any precipitation.
However, decent cold air advection will take place behind this
secondary front and likely cause temperatures to be lower on Tuesday
then today. While this was seen in the models yesterday, it appears
as though the degree of cold air coming in is a bit more impressive.
Low level temps (~925mb) drop back down to -7/-8 deg C by the end of
the day Tuesday. Therefore, we might not get above 40 in our far
northern counties and remain in the low to mid 40s elsewhere, with
sfc high pressure centered over Springfield MO by 00Z Wed.
This colder weather is definitely not here to stay however. We start
to see warm air advection begin in earnest on Tuesday night...as
high pressure slides southeast into the TN valley by 12Z Wednesday.
High pressure continues to move southeast toward the southeast coast
throughout the day, putting our area in increasing southwest flow.
This should pump everyone well into the 40s and 50s for highs Wednesday.
Guidance numbers seem a bit too cool, especially given how warm we
are getting today, although we did start out warmer this morning.
Tuesday nights lows via guidance seem too cold though and that is
likely why they are lower for highs on Wednesday. It seems more
logical that highs should top out in the upper 40s to mid 50s.
.LONG TERM...(Thursday through Monday)
ISSUED AT 228 PM CST MON DEC 16 2013
The latest long range models are in general agreement, that a
frontal boundary will enter into the area Friday, then slow down
through Saturday night, then push east of the area on Sunday as low
pressure tracks NE from the Ozarks to the Ohio Valley region. Mild
temperatures are forecast Thursday through Saturday. Turning colder
again Sunday.
Scattered showers are forecast as early as Thursday night into
Friday as weak mid level support, increased moisture and low level
warm advection support the chance. Upper system is forecast to track
across Old Mexico, then turn NE into the southern Plains and
eventually mid Mississippi Valley region over the weekend. An
increase in moisture and ascent is expected Friday night through
Saturday night, with periods of showers (and a few thunderstorms
given the persistent elevated instability forecast). Locally heavy
rain appears a good possibility given the forecast upper air pattern
supports this scenario. Forecast precipitable water values are
expected to exceed 1.5" which is above the 99th percentile for this
time of year. Still time for the models to adjust and lock in. So
expect adjustments and such as we progress through the week. Could
be a window of opportunity for strong storms late Saturday night
into Sunday morning if the aforementioned low tracks along the Ohio
River. Some of the models show very strong wind fields and a hint of
surface based instability, mainly over west KY. Will see. Again,
adjustments will likely be made. Falling temps expected Sunday in
the wake of the front. Cannot rule out very light snow or flurries
on the backside of the system late Sunday / Sunday night. Will not
play this up at all, as the models show decreasing moisture in the
confluence region of the phasing positive tilt mid level trof over
the nation`s mid section.
Dry and cold weather is forecast Monday with high pressure back
across the area.
&&
.AVIATION...
ISSUED AT 1037 AM CST MON DEC 16 2013
SSW winds today up to 10 kts, with just a few mid/high clouds.
Confidence in lower clouds tonight is low. NAM guidance more
suggestive of low clouds, fog potential than the GFS. The RAP shows
moisture near surface, dry aloft. Should winds become light enough
and with more snow melt today, will have to monitor for low cloud
and/or patchy fog potential. For now, just a hedge forecast in that
direction.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
SHORT TERM...CW
LONG TERM...CN
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1037 AM CST Mon Dec 16 2013
.SHORT TERM...(Today through Wednesday)
ISSUED AT 348 AM CST MON DEC 16 2013
Low clouds have cleared much of the region early this morning,
with the exception of perhaps a few locations in the Evansville
tri-state area. The low clouds were replaced by mid level clouds
accompanying the passage of a mid level disturbance overnight.
Model guidance indicates these clouds should clear the region from
west to east through the morning. Some redevelopment of low clouds
is possible by late morning and afternoon with lingering low level
moisture still in place. However, their impact should gradually
lessen as we progress towards mid week.
Over the last 24 hours, we have expressed some concern for fog
development for the next few nights as low level warm advection
develops over top a cold moist snow covered ground. Despite what
some raw model guidance was suggesting last night, little to no
fog has formed over southeast Missouri thus far. Winds have stayed
up overnight, but this should not inhibit the advection fog
process we thought might occur. The air advecting into the region
from the southwest is relatively dry, so that may be an inhibiting
factor to fog formation instead, especially with a persistent
light southwest wind. Similar conditions are expected tonight, so
fog will hopefully not be much of an issue. Tuesday night may be
a different story as light winds beneath a clear sky create more
favorable conditions for radiation fog, particularly where any
snow cover still exists. Low confidence precludes a mention in the
forecast at this time - just something to keep in mind nonetheless.
Below normal temperatures will persist today as the region remains
in northwest flow aloft on the back side of a longwave trough over
the east. However, a transition to a more zonal flow pattern by
mid week will help to slowly moderate temperatures through the
period. Highs by Tuesday should top the 40 degree mark in most
locations, and possibly reach close to 50 degrees over southern
portions of the area. Highs on Wednesday are expected to range
from the upper 40s to mid 50s. Weak energy rotating across the
Great Lakes may keep more sky cover in our northeastern counties
through Tuesday, but this influence will lessen by Wednesday with
more sunshine across the entire region.
.LONG TERM...(Wednesday Night through Sunday)
ISSUED AT 119 AM CST MON DEC 16 2013
We start the long term portion of the forecast with subtle shifts
in the pattern that will lead to a moderation in temps. The upper
level flow will be backing, as height falls in the southern Plains
occur in response to a digging upper level jet. Downstream ridging
will work in as upper level southwesterlies aid the moderation
process.
By Thursday, this moderating trend includes moisture, and
elevated/overrunning pops begin to appear from the north and west,
as a front will be taking shape and approach from that direction.
Thursday night-Friday, we see surface dew point temps surging
through the 50s, with 60F not far off. 850 mb winds have increased
to 50 kts. Elevated instability parameters such as the K index
suggest at least an isolated mention of thunder is still possible.
Beyond Friday is where the model divergence takes place. However,
despite the differing solutions, a trend of warmer layer threshold
temps is starting to appear, as both the ECMWF/GFS have trended
this direction the last two forecast nights. The ECMWF keeps a
wetter forecast as the boundary still sets up/hangs in the vcnty
thru the weekend, while the GFS moves it on thru before
stalling/returning it. Both suggest mainly liquid pcpn chances by
and large as a whole, although both also support a changeover
before ending mention by late day 7 into day 8.
&&
.AVIATION...
ISSUED AT 1037 AM CST MON DEC 16 2013
SSW winds today up to 10 kts, with just a few mid/high clouds.
Confidence in lower clouds tonight is low. NAM guidance more
suggestive of low clouds, fog potential than the GFS. The RAP shows
moisture near surface, dry aloft. Should winds become light enough
and with more snow melt today, will have to monitor for low cloud
and/or patchy fog potential. For now, just a hedge forecast in that
direction.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
441 PM EST MON DEC 16 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 347 PM EST MON DEC 16 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOWS PERSISTENT NW
FLOW ALF OVER THE GREAT LKS BTWN DEEP TROF OVER ERN NAMERICA AND RDG
ALONG THE W COAST. VERY COLD CNDN AIR IS IN PLACE OVER THE UPR LKS
WITH H5/H85 TEMPS JUST UNDER -30C/ARND -18 OR 19C. DISTURBANCE
RESPONSIBLE FOR SN ON SUN HAS NOW PUSHED E INTO QUEBEC...BUT ANOTHER
WELL DEFINED CLIPPER SHRTWV JUST E OF LK WINNIPEG EARLY THIS AFTN IS
FOLLOWING QUICKLY BEHIND. SHRTWV RDG/DRY MID LVL AIR SHOWN ON THE
12Z APX/GRB RAOBS BROUGHT DRY WX TO UPR MI EARLY THIS AFTN. ALTHOUGH
ABSOLUTE MSTR IS LIMITED FOR THE TRAILING DISTURBANCE WITH 12Z PWATS
NO HIER THAN 0.25-0.35 INCH IN MN...A BAND OF SN UNDER THE DEEP LYR
QVECTOR CNVGC/DPVA/ISENTROPIC ASCENT AHEAD OF THIS FEATURE IS MOVING
INTO WRN LK SUP. THE BAND IS RATHER NARROW...BUT VSBYS UNDER THE
HEAVIER SN HAVE FALLEN AS LO AS 1/4-3/4 MILES. THIS SN BAND SHIFTED
INTO THE WRN COUNTIES BY MID AFTN...AND THE VSBY AT IWD DROPPED TO
1/4SM FOR AN HR. SOME SHSN AND PERHAPS A VORTEX ARE PRESENT OVER
NCNTRL LK MI...AND THESE ARE DRIFTING TO THE NNE. ALTHOUGH SOME
LIGHT SN LINGERS BACK INTO NW MN BEHIND THIS BAND...VSBYS THERE ARE
AOA 3 MILES UNDER THE UPR LVL DRYING SHOWN ON WV IMAGERY/QVECTOR
DVGC IN THE WAKE OF THE SHRTWV TROF. IN FACT...THERE HAS BEEN SOME
CLRG OVER CENTRAL MN. FARTHER TO THE NW...THERE IS ANOTHER CLIPPER
DISTURBANCE DIGGING SEWD IN SASKATCHEWAN.
MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE POPS/SN AMNTS AND GOING
HEADLINE OVER THE ERN CWA ASSOCIATED WITH APRCHG CLIPPER SHRTWV.
FOCUS FOR TUE SHIFTS TO POTENTIAL IMPACT OF SECOND TRAILING
DISTURBANCE IN WRN CANADA AS WELL AS THE CHC FOR MORE LK EFFECT SN.
LATE THIS AFTN/THRU THIS EVNG...TENDED TO BUMP POPS UP TO
CATEGORICAL FOR A FEW HRS AT MOST PLACES W-E THIS AFTN INTO EARLY
EVNG WITH PASSAGE OF RATHER NARROW BAND OF SN UNDER AXIS OF H85-5
QVECTOR CNVGC AHEAD OF APRCHG SHRTWV. WITH 2G/KG SPECIFIC HUMIDITY
PRESENT NEAR H725 AND A 2-3 HR PERIOD OF HEAVIER SN...EXPECT MOST
PLACES WL SEE ARND AN INCH TO PERHAPS 2 INCHES OF SN UNDER THIS
HEAVIER BURST. THE ONE EXCEPTION WL BE IN THE SSW FLOW DOWNWIND OF
LK MI...WHERE SOME LK ENHANCEMENT WITH H85 TEMPS NEAR -16C/DEEPER
MSTR/DYNAMIC FORCING JUSTIFIES GOING WINTER WX ADVY UNTIL PASSAGE OF
THE BAND/WSHFT TO THE WSW AFT MIDNGT OVER THE E WL DIMINISH THESE
SHSN. FVRBL OMEGA PROFILE WITHIN THE DGZ WL AID IN SN ACCUMS. TO THE
W...JUST SOME LINGERING SCT -SHSN WL FOLLOW THE BAND UNDER MID LVL
DRYING/QVECTOR DVGC. WHERE THERE IS A BETTER CHC FOR AT LEAST
PARTIAL CLRG OVER THE SCNTRL...TENDED TO LOWER FCST MIN TEMPS A BIT
WELL INTO THE SINGLE NUMBERS ABV ZERO.
LATER TNGT/TUE...MOST OF THE EARLY MRNG SHOULD BE MOCLDY WITH JUST
SOME SCT -SHSN/FLURRIES UNDER QVECTOR DVGC IN THE WAKE OF THE
DEPARTING CLIPPER. THE SHRTWV NOW OVER SASKATCHEWAN IS FCST TO DIG
SEWD AND INTO THE UPR LKS BY 12Z TUE. ALTHOUGH MORE IMPRESSIVE
MSTR/DYNAMIC FORCING WL ACCOMPANY ANOTHER SHRTWV PASSING TO THE S IN
WI...ARRIVAL OF COLD FNT/DEEPER MSTR ASSOCIATED WITH THE
SASKATCHEWAN DISTURBANCE WL BRING A RETURN OF HIER POPS TO MAINLY NW
UPR MI ON TUE MRNG. THERE IS SOME DISAGREEMENT AMONG THE MODELS ON
HOW MUCH DEEPER MSTR WL ACCOMPANY THIS FROPA. IN GENERAL...THE 12Z
NAM/GFS SHOW MORE FVRBL ALIGNMENT BTWN THE DEEPER MSTR AND FROPA
TIMING. ALTHOUGH THERE IS SOME POTENTIAL FOR A BRIEF PERIOD OF LK
ENHANCED SN WITH H85 TEMPS RISING TO -10C IN THE NARROW THERMAL RDG
AHEAD OF THIS FNT...THE NAM/GFS SHOW DEEPER MSTR LINGERING FOR ONLY
A 3-6HR PERIOD. AS THE FNT SHIFTS TO THE E...THESE SHSN WL FOLLOW
THE BNDRY...WITH THE HIER POPS CLOSER TO LK SUP. BUT WL CARRY LOWER
CHC POPS EVEN OVER THE SCENTRAL...WHICH WL BE CLOSER TO THE DYNAMIC
FORCING ASSOCIATED WITH SHRTWV PASSING THRU WI. AFTER THE HEAVIER
SHSN END OVER THE NW...EXPECT LIGHTER MULTIPLE BAND LES TO IMPACT
THE WNW WIND SN BELTS THERE AS COLDER AIR WITH H85 TEMPS FALLING TO
ARND -18C BY 00Z WED FOLLOW THE BNDRY. NOT OUT OF THE QUESTION THERE
COULD BE ADVY SN FALL OVER THE NW THRU THE DAY...BUT CONCERNS
ABOUT TIMING OF DEEPER MSTR LOWER CONFIDENCE ENUF TO HOLD OFF ON A
HEADLINE FOR NOW.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 440 PM EST MON DEC 16 2013
EXPECT CONTINUED NW FLOW OVER THE KEWEENAW PENINSULA TUESDAY EVENING
WITH ANOTHER 1 TO ALMOST 2IN. A QUICK 1-4IN OF SNOW WILL BE POSSIBLE
E OF MUNISING AND N OF NEWBERRY TUESDAY NIGHT. MAY NEED TO HOIST A
LES ADVISORY FOR E ALGER AND N PORTIONS OF LUCE COUNTY...WITH THE
CONVERGENCE BEHIND THE EXITING LOW.
WITH THE 500MB TROUGH SET UP FROM E ONTARIO THROUGH THE LOWER GREAT
LAKES...AND A SIZABLE RIDGE DOMINATING THE W HALF OF THE
NATION...CHANCES ARE GOOD FOR RIDGING TO MOVE IN FOR MID WEEK. THE
RIDGE WILL SLIDE IN AT THE SFC AND ALOFT WEDNESDAY MORNING...AHEAD
OF A BROAD AREA OF LOW PRESSURE SET UP FROM SW AND SCENTRAL CANADA
THROUGH THE NORTHERN PLAINS. THE WARM WEATHER WILL CONTINUE FOR
WEDNESDAY AHEAD OF THIS LOW. ENJOY IT WHILE IT LASTS. WHILE READINGS
WILL BE ABOVE WHAT WE HAVE BEEN USE TO /HAVE NOT HAD TEMPS ABOVE 15F
AT NWS MQT SINCE THE FIRST 5 DAYS OF DECEMBER/...THEY WILL REMAIN
AROUND NORMAL FOR THIS TIME OF YEAR. HIGHS ARE TYPICALLY IN THE MID
TO UPPER 20S IN MID DECEMBER.
EXPECT THE RIDGE ALOFT TO QUICKLY TURNING TO MORE ZONAL FLOW
WEDNESDAY NIGHT WITH BOOKEND TROUGHS OVER THE FAR W AND E SECTIONS
OF THE UNITED STATES. BY 00Z THURSDAY THE SFC LOW WILL HAVE MOVED TO
THE SE...STRETCHING FROM E CO THROUGH LAKE SUPERIOR.
THE N EXTENT OF THE SFC LOW WILL SLOWLY SINK ACROSS LAKE MI AND
LOWER MI THROUGH THE DAY THURSDAY...WITH SW FLOW AT 500MB ON
THURSDAY IN RESPONSE TO THE LOW DIVING ALONG THE W COAST INTO
CA...AND THE NORTHERN LOW PUSHING ACROSS CENTRAL CANADA. A QUICK
TENTH OF AN INCH OR SO OF LIQUID FROM THURSDAY AFTERNOON THROUGH
THURSDAY EVENING. WITH SNOW RATIOS OF 20-25:1...WILL LIKELY HAVE
1-2IN OF SNOW CWA WIDE BY MIDNIGHT.
THE SFC LOW WILL THEN CONSOLIDATE ACROSS LOWER MI AND LAKE HURON AT
12Z FRIDAY...WITH UPPER MI AND THE UPPER GREAT LAKES RETURNING TO
OUR TROUGH PATTERN FROM THURSDAY THROUGH NEXT MONDAY. ANOTHER 1-2IN
OF SNOW POSSIBLE BEFORE DRYING UP BY LATE FRIDAY MORNING.
A BRIEF RIDGE WILL ATTEMPT TO BUILD IN ALOFT SATURDAY OVER THE SE
CWA...AS THE NEXT SIGNIFICANT TROUGH PUSHES IN FROM CENTRAL CANADA
AND THE PLAINS STATES. A SERIES OF EMBEDDED WAVES WILL CONTINUE TO
NEAR FROM THE NW THROUGH AT LEAST MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1222 PM EST MON DEC 16 2013
EXPECT VFR CONDITIONS AT TAF ISSUANCE TO DETERIORATE TO IFR W-E AS A
BAND OF SN CROSSES UPR MI W-E. THERE MAY BE BRIEF PERIOD OF LIFR
CONDITIONS WHEN THE SN IS HEAVIEST. THIS BAND OF SN WL SHIFT E OF
SAW AFT 00Z. CONDITIONS IN THE WAKE OF THIS BAND ARE LIKELY TO
IMPROVE TO MVFR AND THEN PERHAPS VFR UNDER MID LVL DRYING AT IWD AND
SAW...WHERE THE EXPECTED W-SW FLOW IN ITS WAKE WL DOWNSLOPE. CMX IS
LIKELY TO HOLD ON TO MVFR CONDITIONS. THE ARRIVAL OF ANOTHER LO PRES
TROF/DEEPER MSTR WL BRING A PERIOD OF HEAVIER SHSN/IFR CONDITIONS TO
CMX/IWD ON TUE MRNG...BUT DOWNSLOPE NATURE OF THE W WIND INDICATES
NO WORSE THAN MVFR WX AT SAW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 355 PM EST MON DEC 16 2013
S WINDS UP TO 25 TO 30 KTS THIS AFTERNOON AHEAD OF AN APPROACHING
LOW PRESSURE TROUGH WILL SHIFT TO THE SW AND DIMINISH OVERNIGHT TO
20 TO 25 KTS AS THE TROUGH SHIFTS TO THE EAST. A STRONGER WEST TO
NORTHWEST WIND UP TO 30 KTS WILL DEVELOP ON TUE FOLLOWING THE
PASSAGE OF A COLD FRONT. NOT OUT OF THE QUESTION THERE COULD BE A
FEW GUSTS TO NEAR GALE FORCE OVER WESTERN LAKE SUPERIOR. NO GALES
ARE FORESEEN QUITE YET FROM TUESDAY NIGHT THROUGH
SATURDAY...ALTHOUGH A COUPLE OF PERIODS GET CLOSER TO GUSTS OF
25-30KTS. HIGH PRESSURE WILL MOVE INTO THE CENTRAL PLAINS TUESDAY
EVENING AND WILL PUSH A BRIEF RIDGE ACROSS LAKE SUPERIOR WEDNESDAY.
A TROUGH EXTENDING FROM A BROAD LOW OVER THE ROCKIES AND NORTHERN
PLAINS WILL MOVE INTO THE UPPER GREAT LAKES WEDNESDAY NIGHT AND
THURSDAY. EXPECT THE LOW TO SINK ACROSS LOWER MICHIGAN BY FRIDAY
MORNING. IN THE WAKE OF THE LOW...HIGH PRESSURE OVER THE CENTRAL
PLAINS FRIDAY MORNING SHOULD SLOWLY BUILD INTO THE UPPER GREAT LAKES
ON FRIDAY...AND REMAIN IN PLACE THROUGH FRIDAY NIGHT. WEAK LOW
PRESSURE WILL THEN PUSH ACROSS THE AREA FOR THE START OF THE WEEKEND.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 1 AM EST TUESDAY FOR MIZ007-014.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...KC
MARINE...KC/KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
355 PM EST MON DEC 16 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 347 PM EST MON DEC 16 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOWS PERSISTENT NW
FLOW ALF OVER THE GREAT LKS BTWN DEEP TROF OVER ERN NAMERICA AND RDG
ALONG THE W COAST. VERY COLD CNDN AIR IS IN PLACE OVER THE UPR LKS
WITH H5/H85 TEMPS JUST UNDER -30C/ARND -18 OR 19C. DISTURBANCE
RESPONSIBLE FOR SN ON SUN HAS NOW PUSHED E INTO QUEBEC...BUT ANOTHER
WELL DEFINED CLIPPER SHRTWV JUST E OF LK WINNIPEG EARLY THIS AFTN IS
FOLLOWING QUICKLY BEHIND. SHRTWV RDG/DRY MID LVL AIR SHOWN ON THE
12Z APX/GRB RAOBS BROUGHT DRY WX TO UPR MI EARLY THIS AFTN. ALTHOUGH
ABSOLUTE MSTR IS LIMITED FOR THE TRAILING DISTURBANCE WITH 12Z PWATS
NO HIER THAN 0.25-0.35 INCH IN MN...A BAND OF SN UNDER THE DEEP LYR
QVECTOR CNVGC/DPVA/ISENTROPIC ASCENT AHEAD OF THIS FEATURE IS MOVING
INTO WRN LK SUP. THE BAND IS RATHER NARROW...BUT VSBYS UNDER THE
HEAVIER SN HAVE FALLEN AS LO AS 1/4-3/4 MILES. THIS SN BAND SHIFTED
INTO THE WRN COUNTIES BY MID AFTN...AND THE VSBY AT IWD DROPPED TO
1/4SM FOR AN HR. SOME SHSN AND PERHAPS A VORTEX ARE PRESENT OVER
NCNTRL LK MI...AND THESE ARE DRIFTING TO THE NNE. ALTHOUGH SOME
LIGHT SN LINGERS BACK INTO NW MN BEHIND THIS BAND...VSBYS THERE ARE
AOA 3 MILES UNDER THE UPR LVL DRYING SHOWN ON WV IMAGERY/QVECTOR
DVGC IN THE WAKE OF THE SHRTWV TROF. IN FACT...THERE HAS BEEN SOME
CLRG OVER CENTRAL MN. FARTHER TO THE NW...THERE IS ANOTHER CLIPPER
DISTURBANCE DIGGING SEWD IN SASKATCHEWAN.
MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE POPS/SN AMNTS AND GOING
HEADLINE OVER THE ERN CWA ASSOCIATED WITH APRCHG CLIPPER SHRTWV.
FOCUS FOR TUE SHIFTS TO POTENTIAL IMPACT OF SECOND TRAILING
DISTURBANCE IN WRN CANADA AS WELL AS THE CHC FOR MORE LK EFFECT SN.
LATE THIS AFTN/THRU THIS EVNG...TENDED TO BUMP POPS UP TO
CATEGORICAL FOR A FEW HRS AT MOST PLACES W-E THIS AFTN INTO EARLY
EVNG WITH PASSAGE OF RATHER NARROW BAND OF SN UNDER AXIS OF H85-5
QVECTOR CNVGC AHEAD OF APRCHG SHRTWV. WITH 2G/KG SPECIFIC HUMIDITY
PRESENT NEAR H725 AND A 2-3 HR PERIOD OF HEAVIER SN...EXPECT MOST
PLACES WL SEE ARND AN INCH TO PERHAPS 2 INCHES OF SN UNDER THIS
HEAVIER BURST. THE ONE EXCEPTION WL BE IN THE SSW FLOW DOWNWIND OF
LK MI...WHERE SOME LK ENHANCEMENT WITH H85 TEMPS NEAR -16C/DEEPER
MSTR/DYNAMIC FORCING JUSTIFIES GOING WINTER WX ADVY UNTIL PASSAGE OF
THE BAND/WSHFT TO THE WSW AFT MIDNGT OVER THE E WL DIMINISH THESE
SHSN. FVRBL OMEGA PROFILE WITHIN THE DGZ WL AID IN SN ACCUMS. TO THE
W...JUST SOME LINGERING SCT -SHSN WL FOLLOW THE BAND UNDER MID LVL
DRYING/QVECTOR DVGC. WHERE THERE IS A BETTER CHC FOR AT LEAST
PARTIAL CLRG OVER THE SCNTRL...TENDED TO LOWER FCST MIN TEMPS A BIT
WELL INTO THE SINGLE NUMBERS ABV ZERO.
LATER TNGT/TUE...MOST OF THE EARLY MRNG SHOULD BE MOCLDY WITH JUST
SOME SCT -SHSN/FLURRIES UNDER QVECTOR DVGC IN THE WAKE OF THE
DEPARTING CLIPPER. THE SHRTWV NOW OVER SASKATCHEWAN IS FCST TO DIG
SEWD AND INTO THE UPR LKS BY 12Z TUE. ALTHOUGH MORE IMPRESSIVE
MSTR/DYNAMIC FORCING WL ACCOMPANY ANOTHER SHRTWV PASSING TO THE S IN
WI...ARRIVAL OF COLD FNT/DEEPER MSTR ASSOCIATED WITH THE
SASKATCHEWAN DISTURBANCE WL BRING A RETURN OF HIER POPS TO MAINLY NW
UPR MI ON TUE MRNG. THERE IS SOME DISAGREEMENT AMONG THE MODELS ON
HOW MUCH DEEPER MSTR WL ACCOMPANY THIS FROPA. IN GENERAL...THE 12Z
NAM/GFS SHOW MORE FVRBL ALIGNMENT BTWN THE DEEPER MSTR AND FROPA
TIMING. ALTHOUGH THERE IS SOME POTENTIAL FOR A BRIEF PERIOD OF LK
ENHANCED SN WITH H85 TEMPS RISING TO -10C IN THE NARROW THERMAL RDG
AHEAD OF THIS FNT...THE NAM/GFS SHOW DEEPER MSTR LINGERING FOR ONLY
A 3-6HR PERIOD. AS THE FNT SHIFTS TO THE E...THESE SHSN WL FOLLOW
THE BNDRY...WITH THE HIER POPS CLOSER TO LK SUP. BUT WL CARRY LOWER
CHC POPS EVEN OVER THE SCENTRAL...WHICH WL BE CLOSER TO THE DYNAMIC
FORCING ASSOCIATED WITH SHRTWV PASSING THRU WI. AFTER THE HEAVIER
SHSN END OVER THE NW...EXPECT LIGHTER MULTIPLE BAND LES TO IMPACT
THE WNW WIND SN BELTS THERE AS COLDER AIR WITH H85 TEMPS FALLING TO
ARND -18C BY 00Z WED FOLLOW THE BNDRY. NOT OUT OF THE QUESTION THERE
COULD BE ADVY SN FALL OVER THE NW THRU THE DAY...BUT CONCERNS
ABOUT TIMING OF DEEPER MSTR LOWER CONFIDENCE ENUF TO HOLD OFF ON A
HEADLINE FOR NOW.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 400 AM EST MON DEC 16 2013
UPPER TROUGH THAT WILL SWING INTO THE REGION THIS AFTERNOON AND
TONIGHT WILL CONTINUE TO INFLUENCE THE UPPER GREAT LAKES REGION ON
TUESDAY BEFORE DEPARTING ON TUESDAY NIGHT. AT THE SURFACE...AN
ELONGATED TROUGH WILL BE STRETCHING SOUTH FROM HUDSON BAY TO NORTHERN
LAKE SUPERIOR AT 12Z TUESDAY AND IT WILL SHIFT EAST THROUGH THE DAY.
THIS SHIFT WILL ALLOW FOR COLDER 850MB TEMPERATURES TO SLIDE
SOUTHEAST ACROSS UPPER MICHIGAN THROUGH THE DAY (FROM -10C AT 12Z TO
-16C AT 00Z WEDNESDAY). ALTHOUGH THERE ARE SOME MINOR DIFFERENCES IN
THE MODELS ON THE 850MB TEMPS...THEY ARE FAIRLY CONSISTENT IN THE
WIND FIELDS WITH WEST-NORTHWESTERLY FLOW ACROSS THE AREA. MOISTURE ON
THE OTHER HAND IS ALL OVER THE MAP AND LEADS TO UNCERTAINTY ON THE
SNOWFALL AMOUNTS IN THE WNW SNOW BELTS. THERE SHOULD BE ENOUGH LOW
LEVEL MOISTURE FOR SOME LIGHT LAKE EFFECT SNOW TO START TUESDAY
MORNING (EVEN THOUGH DELTA-T VALUES ARE A LITTLE MARGINAL). BUT WITH
THE 850-700MB MOISTURE LACKING OVER MUCH OF THE AREA AS THE MAIN AREA
SLIDES SOUTH OF THE CWA WITH AN EMBEDDED SHORTWAVE...WOULD EXPECT
ACCUMULATIONS TO BE LIGHT. MODEL QPF SEEMS TO PICK UP ON THIS IDEA
FAIRLY WELL AND ONLY SHOW VERY LIGHT AMOUNTS FOR THE FIRST PART OF
THE MORNING. BUT AS THE COLDER AIR AND DEEPER MOISTURE SWEEP IN
DURING THE AFTERNOON WITH A WEAK SHORTWAVE...WOULD EXPECT THE
INTENSITY OF THE SHOWERS TO INCREASE AS INVERSION HEIGHTS RISE TO
8-10KFT AND LAKE INDUCED CAPES RISE TO 400-500 J/KG. MODEL SOUNDINGS
SHOW MUCH OF THE FAVORED LIFT TO BE RIGHT WITHIN THE DGZ...SO WOULD
EXPECT SNOW RATIOS TO BE HIGHER END DURING THE AFTERNOON AND FIRST
PART OF THE EVENING (MID-UPPER 20S). DID TREND RATIOS UP TOWARDS THAT
VALUE...BUT WILL NEED TO KEEP AN EYE ON BL WINDS...BECAUSE THE
STRONGER WINDS INDICATED BY THE NAM (NEARING 30KTS) MAY BE ENOUGH TO
FRACTURE THE FLAKES AND REDUCE RATIOS. WITH THIS FAVORABLE
PERIOD...DID TREND SNOW AMOUNTS UP FOR THE HIGHER TERRAIN FROM
ROCKLAND THROUGH THE KEWEENAW (TO 2-4 INCHES) THROUGH THE EVENING
HOURS. IN ADDITION...THE SHORTWAVE FORCING...BETTER MOISTURE AND
20-25KT BL WINDS WOULD EXPECT THE SNOW SHOWERS TO HANG TOGETHER
FARTHER INLAND THAN PURE LAKE EFFECT AND HAVE CHANCE OF SNOW SHOWERS
STRETCHING EAST TO COVER MUCH OF THE WESTERN HALF OF THE U.P.
WITH THE DELAYED ARRIVAL OF THE COLDER AIR AND MOISTURE...TRENDED
POPS BACK SIGNIFICANTLY OVER THE EAST TO START TUESDAY. WOULD EXPECT
A PERIOD OF LITTLE TO NO SNOW INTO THE FIRST PART OF THE
AFTERNOON...BEFORE THE COLDER AIR ARRIVES BEHIND THE TROUGH AND
INCREASES THE SNOW THROUGH THE EVENING. WHILE THE SNOW IS INCREASING
OVER THE EAST...THERE SHOULD BE A DIMINISHING TREND OVER THE WEST
DUE TO AN INCOMING HIGH PRESSURE RIDGE. BUFKIT SOUNDINGS ARE SHOWING
SIGNIFICANT FALLS TO THE INVERSION HEIGHTS (BELOW 4KFT OVERNIGHT)
WITH THE ASSOCIATED SUBSIDENCE. THEREFORE...WILL CONTINUE TO SHOW
THE DIMINISHING IDEA WITH THE POPS FIRST OVER THE WEST AND THEN THE
EAST LATE IN THE NIGHT. OVERALL...WOULD THINK AREAS EAST OF
MUNISING WOULD SEE SNOWFALL AMOUNTS THROUGH TUESDAY NIGHT OF 2-5
INCHES.
THE ACTIVE PERIOD OF WEAK SYSTEMS CONTINUES ON WEDNESDAY AS
SHORTWAVE QUICKLY SLIDES THROUGH UPPER MICHIGAN. MODELS HAVE
TRENDED FARTHER NORTH WITH THIS WAVE AND ASSOCIATED WARM AIR
ADVECTION THAN 24HRS AGO...WHICH PUTS THE MAIN AXIS OF THE LIGHT
SNOW OVER NORTHERN UPPER MICHIGAN OR LAKE SUPERIOR. A WEAK SURFACE
LOW WILL ALSO BE ASSOCIATED WITH THIS WAVE...WITH A TRACK SIMILAR
BUT DELAYED FROM THE SNOW AXIS. WILL ATTEMPT TO PROVIDE BETTER
TIMING ON THE SNOW/POPS FOR WEDNESDAY AS IT TRAVELS ACROSS THE CWA.
WILL KEEP POPS AT CHANCE VALUES AT THIS POINT DUE TO THERE STILL
BEING MODEL DIFFERENCES IN THE EXACT LOCATIONS OF BEST SNOW.
AMOUNTS SHOULD BE ON THE LIGHT SIDE...WITH A DUSTING TO MAYBE
1-1.5IN. SNOW RATIOS WILL LIKELY BE IN THE UPPER TEENS OR AROUND
20...SINCE THE FORCING IS IN THE DGZ BUT WINDS IN THAT AREA WILL
LIKELY FRACTURE THE FLAKES ENOUGH TO KEEP THE RATIOS FROM BEING
HIGHER.
MODELS DIFFER ON THE LOW LEVEL AND SURFACE FEATURES WEDNESDAY NIGHT
INTO THURSDAY AND LEADS TO UNCERTAINTY ON PCPN FORECAST. UPPER
GREAT LAKES REGION WILL BE UNDER NEARLY ZONAL FLOW FOR THIS TIME
FRAME AS AN UPPER TROUGH BEGINS TO DEVELOP OVER THE WESTERN CONUS.
DECENT DIFFERENCES IN THE 00Z GEM/ECMWF AND THE 00Z GFS IN HOW FAR
NORTH THE UPPER JET WILL BE...WHICH INFLUENCES THE LOWER LEVEL
TEMPERATURE FIELDS. AT THE SURFACE...THE GEM/ECMWF/UKMET HOLD A
SURFACE TROUGH OVER THE GREAT LAKES REGION THAT STRETCHES SOUTHWEST
TO THE DEVELOPING LOW THAT WILL BE CONTROLLING THE WEATHER FOR
THURSDAY NIGHT. GFS ON THE OTHERHAND HAS THE TROUGH FARTHER TO THE
SOUTH AND A HIGH PRESSURE RIDGE FROM A HIGH IN SOUTHERN
SASKATCHEWAN NOSING OVER LAKE SUPERIOR (OTHER MODELS KEEP IT IN
SOUTHERN ONTARIO). THESE LITTLE DIFFERENCES HAVE A FAIRLY
SIGNIFICANT AFFECT ON PRECIPITATION MODE WITH 850MB TEMPS AROUND 3C
COOLER (-13C OVER LAKE SUPERIOR) AND LOCATIONS (GFS MORE NORTHERLY
THAN EAST-NORTHEAST SEEN ON GEM/ECMWF). IN ADDITION...ECMWF DOES
SHOW SOME BROAD WARM AIR ADVECTION ALONG THE THERMAL BOUNDARY ON
THURSDAY THAT COULD LEAD TO MORE SYNOPTIC SNOW. OVERALL...WILL
GO WITH CHANCE POPS ON THURSDAY...MAINLY OVER THE NORTHWEST
HALF OF THE CWA AND HAVE SOME HIGHER VALUES OVER THE KEWEENAW WHERE
THE SNOW WILL BE MOST LIKELY.
DIFFERENCES CONTINUE WITH LOW THAT IS EXPECTED TO MOVE OUT OF THE
CENTRAL PLAINS AND THROUGH THE GREAT LAKES REGION. ITS TRACK WILL
LARGELY BE DETERMINED ON WHICH MODELS SURFACE TROUGH POSTION IS
CORRECT...AS IT WILL TRACK ALONG THAT SAME PATH. THUS...ECMWF/GEM
ARE FARTHER NORTH (MOVING THROUGH NORTHERN/CENTRAL LOWER MICHIGAN)
AND THE GFS SLIDES IT ACROSS LAKE ERIE. THIS ALSO AFFECTS THERMAL
FIELDS...BUT THE U.P. SHOULD SEE IT STAYING AS ALL SNOW EVEN
IF THE ECMWF SOLUTION IS CORRECT. WOULD EXPECT AN AREA OF FGEN
PRECIPITATION TO MOVE ACROSS UPPER MICHIGAN...BUT LOCATION IS TOO
UNCERTAIN AT THIS POINT. ALSO...925-850MB TEMPS SHOULD BE COLD
ENOUGH FOR ENHANCEMENT OFF LAKE SUPERIOR WITH THE NORTHERLY WINDS.
WILL CONTINUE TO SHOW HIGH CHANCE OR LIKELY POPS FOR THE THURSDAY
NIGHT PERIOD AND WOULD THINK A GENERAL 2-4 INCHES OF SNOW WOULD BE
EXPECTED IF USING A BLEND OF THE GEM/ECMWF. THE HIGHEST AMOUNTS
WOULD BE NEAR LAKE SUPERIOR AND IF THE FGEN AND LAKE ENHANCEMENT
LOCATIONS LINE UP TOTALS COULD BE A LITTLE HIGHER.
BEHIND THE LOW...WOULD EXPECT A PERIOD OF LAKE EFFECT ON FRIDAY
BEFORE QUICKLY DIMINISHING AS HIGH PRESSURE TAKES HOLD. TOO MUCH
UNCERTAINTY IN THE MODELS FOR THE WEEKEND WEATHER...BUT NO
SIGNIFICANT SNOW IS EXPECTED. WILL LIKELY SEE LAKE EFFECT
SNOW NEAR LAKE SUPERIOR ON SUNDAY AS WINDS TURN NORTHERLY
AND 850MB TEMPERATURES FALL BEHIND A WEAK LOW. HIGHS THIS WEEKEND
(TEENS) LOOK TO CONTINUE THE BELOW NORMAL TREND THIS MONTH.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1222 PM EST MON DEC 16 2013
EXPECT VFR CONDITIONS AT TAF ISSUANCE TO DETERIORATE TO IFR W-E AS A
BAND OF SN CROSSES UPR MI W-E. THERE MAY BE BRIEF PERIOD OF LIFR
CONDITIONS WHEN THE SN IS HEAVIEST. THIS BAND OF SN WL SHIFT E OF
SAW AFT 00Z. CONDITIONS IN THE WAKE OF THIS BAND ARE LIKELY TO
IMPROVE TO MVFR AND THEN PERHAPS VFR UNDER MID LVL DRYING AT IWD AND
SAW...WHERE THE EXPECTED W-SW FLOW IN ITS WAKE WL DOWNSLOPE. CMX IS
LIKELY TO HOLD ON TO MVFR CONDITIONS. THE ARRIVAL OF ANOTHER LO PRES
TROF/DEEPER MSTR WL BRING A PERIOD OF HEAVIER SHSN/IFR CONDITIONS TO
CMX/IWD ON TUE MRNG...BUT DOWNSLOPE NATURE OF THE W WIND INDICATES
NO WORSE THAN MVFR WX AT SAW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 355 PM EST MON DEC 16 2013
S WINDS UP TO 25 TO 30 KTS THIS AFTERNOON AHEAD OF AN APPROACHING
LOW PRESSURE TROUGH WILL SHIFT TO THE SW AND DIMINISH OVERNIGHT TO
20 TO 25 KTS AS THE TROUGH SHIFTS TO THE EAST. A STRONGER WEST TO
NORTHWEST WIND UP TO 30 KTS WILL DEVELOP ON TUE FOLLOWING THE
PASSAGE OF A COLD FRONT. NOT OUT OF THE QUESTION THERE COULD BE A
FEW GUSTS TO NEAR GALE FORCE OVER WESTERN LAKE SUPERIOR. NO GALES
ARE FORESEEN QUITE YET FROM TUESDAY NIGHT THROUGH
SATURDAY...ALTHOUGH A COUPLE OF PERIODS GET CLOSER TO GUSTS OF
25-30KTS. HIGH PRESSURE WILL MOVE INTO THE CENTRAL PLAINS TUESDAY
EVENING AND WILL PUSH A BRIEF RIDGE ACROSS LAKE SUPERIOR WEDNESDAY.
A TROUGH EXTENDING FROM A BROAD LOW OVER THE ROCKIES AND NORTHERN
PLAINS WILL MOVE INTO THE UPPER GREAT LAKES WEDNESDAY NIGHT AND
THURSDAY. EXPECT THE LOW TO SINK ACROSS LOWER MICHIGAN BY FRIDAY
MORNING. IN THE WAKE OF THE LOW...HIGH PRESSURE OVER THE CENTRAL
PLAINS FRIDAY MORNING SHOULD SLOWLY BUILD INTO THE UPPER GREAT LAKES
ON FRIDAY...AND REMAIN IN PLACE THROUGH FRIDAY NIGHT. WEAK LOW
PRESSURE WILL THEN PUSH ACROSS THE AREA FOR THE START OF THE WEEKEND.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 1 AM EST TUESDAY FOR MIZ007-014.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...SRF
AVIATION...KC
MARINE...KC/KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
348 PM EST MON DEC 16 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 347 PM EST MON DEC 16 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOWS PERSISTENT NW
FLOW ALF OVER THE GREAT LKS BTWN DEEP TROF OVER ERN NAMERICA AND RDG
ALONG THE W COAST. VERY COLD CNDN AIR IS IN PLACE OVER THE UPR LKS
WITH H5/H85 TEMPS JUST UNDER -30C/ARND -18 OR 19C. DISTURBANCE
RESPONSIBLE FOR SN ON SUN HAS NOW PUSHED E INTO QUEBEC...BUT ANOTHER
WELL DEFINED CLIPPER SHRTWV JUST E OF LK WINNIPEG EARLY THIS AFTN IS
FOLLOWING QUICKLY BEHIND. SHRTWV RDG/DRY MID LVL AIR SHOWN ON THE
12Z APX/GRB RAOBS BROUGHT DRY WX TO UPR MI EARLY THIS AFTN. ALTHOUGH
ABSOLUTE MSTR IS LIMITED FOR THE TRAILING DISTURBANCE WITH 12Z PWATS
NO HIER THAN 0.25-0.35 INCH IN MN...A BAND OF SN UNDER THE DEEP LYR
QVECTOR CNVGC/DPVA/ISENTROPIC ASCENT AHEAD OF THIS FEATURE IS MOVING
INTO WRN LK SUP. THE BAND IS RATHER NARROW...BUT VSBYS UNDER THE
HEAVIER SN HAVE FALLEN AS LO AS 1/4-3/4 MILES. THIS SN BAND SHIFTED
INTO THE WRN COUNTIES BY MID AFTN...AND THE VSBY AT IWD DROPPED TO
1/4SM FOR AN HR. SOME SHSN AND PERHAPS A VORTEX ARE PRESENT OVER
NCNTRL LK MI...AND THESE ARE DRIFTING TO THE NNE. ALTHOUGH SOME
LIGHT SN LINGERS BACK INTO NW MN BEHIND THIS BAND...VSBYS THERE ARE
AOA 3 MILES UNDER THE UPR LVL DRYING SHOWN ON WV IMAGERY/QVECTOR
DVGC IN THE WAKE OF THE SHRTWV TROF. IN FACT...THERE HAS BEEN SOME
CLRG OVER CENTRAL MN. FARTHER TO THE NW...THERE IS ANOTHER CLIPPER
DISTURBANCE DIGGING SEWD IN SASKATCHEWAN.
MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE POPS/SN AMNTS AND GOING
HEADLINE OVER THE ERN CWA ASSOCIATED WITH APRCHG CLIPPER SHRTWV.
FOCUS FOR TUE SHIFTS TO POTENTIAL IMPACT OF SECOND TRAILING
DISTURBANCE IN WRN CANADA AS WELL AS THE CHC FOR MORE LK EFFECT SN.
LATE THIS AFTN/THRU THIS EVNG...TENDED TO BUMP POPS UP TO
CATEGORICAL FOR A FEW HRS AT MOST PLACES W-E THIS AFTN INTO EARLY
EVNG WITH PASSAGE OF RATHER NARROW BAND OF SN UNDER AXIS OF H85-5
QVECTOR CNVGC AHEAD OF APRCHG SHRTWV. WITH 2G/KG SPECIFIC HUMIDITY
PRESENT NEAR H725 AND A 2-3 HR PERIOD OF HEAVIER SN...EXPECT MOST
PLACES WL SEE ARND AN INCH TO PERHAPS 2 INCHES OF SN UNDER THIS
HEAVIER BURST. THE ONE EXCEPTION WL BE IN THE SSW FLOW DOWNWIND OF
LK MI...WHERE SOME LK ENHANCEMENT WITH H85 TEMPS NEAR -16C/DEEPER
MSTR/DYNAMIC FORCING JUSTIFIES GOING WINTER WX ADVY UNTIL PASSAGE OF
THE BAND/WSHFT TO THE WSW AFT MIDNGT OVER THE E WL DIMINISH THESE
SHSN. FVRBL OMEGA PROFILE WITHIN THE DGZ WL AID IN SN ACCUMS. TO THE
W...JUST SOME LINGERING SCT -SHSN WL FOLLOW THE BAND UNDER MID LVL
DRYING/QVECTOR DVGC. WHERE THERE IS A BETTER CHC FOR AT LEAST
PARTIAL CLRG OVER THE SCNTRL...TENDED TO LOWER FCST MIN TEMPS A BIT
WELL INTO THE SINGLE NUMBERS ABV ZERO.
LATER TNGT/TUE...MOST OF THE EARLY MRNG SHOULD BE MOCLDY WITH JUST
SOME SCT -SHSN/FLURRIES UNDER QVECTOR DVGC IN THE WAKE OF THE
DEPARTING CLIPPER. THE SHRTWV NOW OVER SASKATCHEWAN IS FCST TO DIG
SEWD AND INTO THE UPR LKS BY 12Z TUE. ALTHOUGH MORE IMPRESSIVE
MSTR/DYNAMIC FORCING WL ACCOMPANY ANOTHER SHRTWV PASSING TO THE S IN
WI...ARRIVAL OF COLD FNT/DEEPER MSTR ASSOCIATED WITH THE
SASKATCHEWAN DISTURBANCE WL BRING A RETURN OF HIER POPS TO MAINLY NW
UPR MI ON TUE MRNG. THERE IS SOME DISAGREEMENT AMONG THE MODELS ON
HOW MUCH DEEPER MSTR WL ACCOMPANY THIS FROPA. IN GENERAL...THE 12Z
NAM/GFS SHOW MORE FVRBL ALIGNMENT BTWN THE DEEPER MSTR AND FROPA
TIMING. ALTHOUGH THERE IS SOME POTENTIAL FOR A BRIEF PERIOD OF LK
ENHANCED SN WITH H85 TEMPS RISING TO -10C IN THE NARROW THERMAL RDG
AHEAD OF THIS FNT...THE NAM/GFS SHOW DEEPER MSTR LINGERING FOR ONLY
A 3-6HR PERIOD. AS THE FNT SHIFTS TO THE E...THESE SHSN WL FOLLOW
THE BNDRY...WITH THE HIER POPS CLOSER TO LK SUP. BUT WL CARRY LOWER
CHC POPS EVEN OVER THE SCENTRAL...WHICH WL BE CLOSER TO THE DYNAMIC
FORCING ASSOCIATED WITH SHRTWV PASSING THRU WI. AFTER THE HEAVIER
SHSN END OVER THE NW...EXPECT LIGHTER MULTIPLE BAND LES TO IMPACT
THE WNW WIND SN BELTS THERE AS COLDER AIR WITH H85 TEMPS FALLING TO
ARND -18C BY 00Z WED FOLLOW THE BNDRY. NOT OUT OF THE QUESTION THERE
COULD BE ADVY SN FALL OVER THE NW THRU THE DAY...BUT CONCERNS
ABOUT TIMING OF DEEPER MSTR LOWER CONFIDENCE ENUF TO HOLD OFF ON A
HEADLINE FOR NOW.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 400 AM EST MON DEC 16 2013
UPPER TROUGH THAT WILL SWING INTO THE REGION THIS AFTERNOON AND
TONIGHT WILL CONTINUE TO INFLUENCE THE UPPER GREAT LAKES REGION ON
TUESDAY BEFORE DEPARTING ON TUESDAY NIGHT. AT THE SURFACE...AN
ELONGATED TROUGH WILL BE STRETCHING SOUTH FROM HUDSON BAY TO NORTHERN
LAKE SUPERIOR AT 12Z TUESDAY AND IT WILL SHIFT EAST THROUGH THE DAY.
THIS SHIFT WILL ALLOW FOR COLDER 850MB TEMPERATURES TO SLIDE
SOUTHEAST ACROSS UPPER MICHIGAN THROUGH THE DAY (FROM -10C AT 12Z TO
-16C AT 00Z WEDNESDAY). ALTHOUGH THERE ARE SOME MINOR DIFFERENCES IN
THE MODELS ON THE 850MB TEMPS...THEY ARE FAIRLY CONSISTENT IN THE
WIND FIELDS WITH WEST-NORTHWESTERLY FLOW ACROSS THE AREA. MOISTURE ON
THE OTHER HAND IS ALL OVER THE MAP AND LEADS TO UNCERTAINTY ON THE
SNOWFALL AMOUNTS IN THE WNW SNOW BELTS. THERE SHOULD BE ENOUGH LOW
LEVEL MOISTURE FOR SOME LIGHT LAKE EFFECT SNOW TO START TUESDAY
MORNING (EVEN THOUGH DELTA-T VALUES ARE A LITTLE MARGINAL). BUT WITH
THE 850-700MB MOISTURE LACKING OVER MUCH OF THE AREA AS THE MAIN AREA
SLIDES SOUTH OF THE CWA WITH AN EMBEDDED SHORTWAVE...WOULD EXPECT
ACCUMULATIONS TO BE LIGHT. MODEL QPF SEEMS TO PICK UP ON THIS IDEA
FAIRLY WELL AND ONLY SHOW VERY LIGHT AMOUNTS FOR THE FIRST PART OF
THE MORNING. BUT AS THE COLDER AIR AND DEEPER MOISTURE SWEEP IN
DURING THE AFTERNOON WITH A WEAK SHORTWAVE...WOULD EXPECT THE
INTENSITY OF THE SHOWERS TO INCREASE AS INVERSION HEIGHTS RISE TO
8-10KFT AND LAKE INDUCED CAPES RISE TO 400-500 J/KG. MODEL SOUNDINGS
SHOW MUCH OF THE FAVORED LIFT TO BE RIGHT WITHIN THE DGZ...SO WOULD
EXPECT SNOW RATIOS TO BE HIGHER END DURING THE AFTERNOON AND FIRST
PART OF THE EVENING (MID-UPPER 20S). DID TREND RATIOS UP TOWARDS THAT
VALUE...BUT WILL NEED TO KEEP AN EYE ON BL WINDS...BECAUSE THE
STRONGER WINDS INDICATED BY THE NAM (NEARING 30KTS) MAY BE ENOUGH TO
FRACTURE THE FLAKES AND REDUCE RATIOS. WITH THIS FAVORABLE
PERIOD...DID TREND SNOW AMOUNTS UP FOR THE HIGHER TERRAIN FROM
ROCKLAND THROUGH THE KEWEENAW (TO 2-4 INCHES) THROUGH THE EVENING
HOURS. IN ADDITION...THE SHORTWAVE FORCING...BETTER MOISTURE AND
20-25KT BL WINDS WOULD EXPECT THE SNOW SHOWERS TO HANG TOGETHER
FARTHER INLAND THAN PURE LAKE EFFECT AND HAVE CHANCE OF SNOW SHOWERS
STRETCHING EAST TO COVER MUCH OF THE WESTERN HALF OF THE U.P.
WITH THE DELAYED ARRIVAL OF THE COLDER AIR AND MOISTURE...TRENDED
POPS BACK SIGNIFICANTLY OVER THE EAST TO START TUESDAY. WOULD EXPECT
A PERIOD OF LITTLE TO NO SNOW INTO THE FIRST PART OF THE
AFTERNOON...BEFORE THE COLDER AIR ARRIVES BEHIND THE TROUGH AND
INCREASES THE SNOW THROUGH THE EVENING. WHILE THE SNOW IS INCREASING
OVER THE EAST...THERE SHOULD BE A DIMINISHING TREND OVER THE WEST
DUE TO AN INCOMING HIGH PRESSURE RIDGE. BUFKIT SOUNDINGS ARE SHOWING
SIGNIFICANT FALLS TO THE INVERSION HEIGHTS (BELOW 4KFT OVERNIGHT)
WITH THE ASSOCIATED SUBSIDENCE. THEREFORE...WILL CONTINUE TO SHOW
THE DIMINISHING IDEA WITH THE POPS FIRST OVER THE WEST AND THEN THE
EAST LATE IN THE NIGHT. OVERALL...WOULD THINK AREAS EAST OF
MUNISING WOULD SEE SNOWFALL AMOUNTS THROUGH TUESDAY NIGHT OF 2-5
INCHES.
THE ACTIVE PERIOD OF WEAK SYSTEMS CONTINUES ON WEDNESDAY AS
SHORTWAVE QUICKLY SLIDES THROUGH UPPER MICHIGAN. MODELS HAVE
TRENDED FARTHER NORTH WITH THIS WAVE AND ASSOCIATED WARM AIR
ADVECTION THAN 24HRS AGO...WHICH PUTS THE MAIN AXIS OF THE LIGHT
SNOW OVER NORTHERN UPPER MICHIGAN OR LAKE SUPERIOR. A WEAK SURFACE
LOW WILL ALSO BE ASSOCIATED WITH THIS WAVE...WITH A TRACK SIMILAR
BUT DELAYED FROM THE SNOW AXIS. WILL ATTEMPT TO PROVIDE BETTER
TIMING ON THE SNOW/POPS FOR WEDNESDAY AS IT TRAVELS ACROSS THE CWA.
WILL KEEP POPS AT CHANCE VALUES AT THIS POINT DUE TO THERE STILL
BEING MODEL DIFFERENCES IN THE EXACT LOCATIONS OF BEST SNOW.
AMOUNTS SHOULD BE ON THE LIGHT SIDE...WITH A DUSTING TO MAYBE
1-1.5IN. SNOW RATIOS WILL LIKELY BE IN THE UPPER TEENS OR AROUND
20...SINCE THE FORCING IS IN THE DGZ BUT WINDS IN THAT AREA WILL
LIKELY FRACTURE THE FLAKES ENOUGH TO KEEP THE RATIOS FROM BEING
HIGHER.
MODELS DIFFER ON THE LOW LEVEL AND SURFACE FEATURES WEDNESDAY NIGHT
INTO THURSDAY AND LEADS TO UNCERTAINTY ON PCPN FORECAST. UPPER
GREAT LAKES REGION WILL BE UNDER NEARLY ZONAL FLOW FOR THIS TIME
FRAME AS AN UPPER TROUGH BEGINS TO DEVELOP OVER THE WESTERN CONUS.
DECENT DIFFERENCES IN THE 00Z GEM/ECMWF AND THE 00Z GFS IN HOW FAR
NORTH THE UPPER JET WILL BE...WHICH INFLUENCES THE LOWER LEVEL
TEMPERATURE FIELDS. AT THE SURFACE...THE GEM/ECMWF/UKMET HOLD A
SURFACE TROUGH OVER THE GREAT LAKES REGION THAT STRETCHES SOUTHWEST
TO THE DEVELOPING LOW THAT WILL BE CONTROLLING THE WEATHER FOR
THURSDAY NIGHT. GFS ON THE OTHERHAND HAS THE TROUGH FARTHER TO THE
SOUTH AND A HIGH PRESSURE RIDGE FROM A HIGH IN SOUTHERN
SASKATCHEWAN NOSING OVER LAKE SUPERIOR (OTHER MODELS KEEP IT IN
SOUTHERN ONTARIO). THESE LITTLE DIFFERENCES HAVE A FAIRLY
SIGNIFICANT AFFECT ON PRECIPITATION MODE WITH 850MB TEMPS AROUND 3C
COOLER (-13C OVER LAKE SUPERIOR) AND LOCATIONS (GFS MORE NORTHERLY
THAN EAST-NORTHEAST SEEN ON GEM/ECMWF). IN ADDITION...ECMWF DOES
SHOW SOME BROAD WARM AIR ADVECTION ALONG THE THERMAL BOUNDARY ON
THURSDAY THAT COULD LEAD TO MORE SYNOPTIC SNOW. OVERALL...WILL
GO WITH CHANCE POPS ON THURSDAY...MAINLY OVER THE NORTHWEST
HALF OF THE CWA AND HAVE SOME HIGHER VALUES OVER THE KEWEENAW WHERE
THE SNOW WILL BE MOST LIKELY.
DIFFERENCES CONTINUE WITH LOW THAT IS EXPECTED TO MOVE OUT OF THE
CENTRAL PLAINS AND THROUGH THE GREAT LAKES REGION. ITS TRACK WILL
LARGELY BE DETERMINED ON WHICH MODELS SURFACE TROUGH POSTION IS
CORRECT...AS IT WILL TRACK ALONG THAT SAME PATH. THUS...ECMWF/GEM
ARE FARTHER NORTH (MOVING THROUGH NORTHERN/CENTRAL LOWER MICHIGAN)
AND THE GFS SLIDES IT ACROSS LAKE ERIE. THIS ALSO AFFECTS THERMAL
FIELDS...BUT THE U.P. SHOULD SEE IT STAYING AS ALL SNOW EVEN
IF THE ECMWF SOLUTION IS CORRECT. WOULD EXPECT AN AREA OF FGEN
PRECIPITATION TO MOVE ACROSS UPPER MICHIGAN...BUT LOCATION IS TOO
UNCERTAIN AT THIS POINT. ALSO...925-850MB TEMPS SHOULD BE COLD
ENOUGH FOR ENHANCEMENT OFF LAKE SUPERIOR WITH THE NORTHERLY WINDS.
WILL CONTINUE TO SHOW HIGH CHANCE OR LIKELY POPS FOR THE THURSDAY
NIGHT PERIOD AND WOULD THINK A GENERAL 2-4 INCHES OF SNOW WOULD BE
EXPECTED IF USING A BLEND OF THE GEM/ECMWF. THE HIGHEST AMOUNTS
WOULD BE NEAR LAKE SUPERIOR AND IF THE FGEN AND LAKE ENHANCEMENT
LOCATIONS LINE UP TOTALS COULD BE A LITTLE HIGHER.
BEHIND THE LOW...WOULD EXPECT A PERIOD OF LAKE EFFECT ON FRIDAY
BEFORE QUICKLY DIMINISHING AS HIGH PRESSURE TAKES HOLD. TOO MUCH
UNCERTAINTY IN THE MODELS FOR THE WEEKEND WEATHER...BUT NO
SIGNIFICANT SNOW IS EXPECTED. WILL LIKELY SEE LAKE EFFECT
SNOW NEAR LAKE SUPERIOR ON SUNDAY AS WINDS TURN NORTHERLY
AND 850MB TEMPERATURES FALL BEHIND A WEAK LOW. HIGHS THIS WEEKEND
(TEENS) LOOK TO CONTINUE THE BELOW NORMAL TREND THIS MONTH.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1222 PM EST MON DEC 16 2013
EXPECT VFR CONDITIONS AT TAF ISSUANCE TO DETERIORATE TO IFR W-E AS A
BAND OF SN CROSSES UPR MI W-E. THERE MAY BE BRIEF PERIOD OF LIFR
CONDITIONS WHEN THE SN IS HEAVIEST. THIS BAND OF SN WL SHIFT E OF
SAW AFT 00Z. CONDITIONS IN THE WAKE OF THIS BAND ARE LIKELY TO
IMPROVE TO MVFR AND THEN PERHAPS VFR UNDER MID LVL DRYING AT IWD AND
SAW...WHERE THE EXPECTED W-SW FLOW IN ITS WAKE WL DOWNSLOPE. CMX IS
LIKELY TO HOLD ON TO MVFR CONDITIONS. THE ARRIVAL OF ANOTHER LO PRES
TROF/DEEPER MSTR WL BRING A PERIOD OF HEAVIER SHSN/IFR CONDITIONS TO
CMX/IWD ON TUE MRNG...BUT DOWNSLOPE NATURE OF THE W WIND INDICATES
NO WORSE THAN MVFR WX AT SAW.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 449 AM EST MON DEC 16 2013
WITH A HIGH PRESSURE RIDGE OVER THE AREA...GALES HAVE ENDED. NEXT
CHANCE FOR STRONGER WINDS WOULD BE TUESDAY AFTERNOON AS THERE COULD
BE SOME GALE FORCE GUSTS TO 35 KNOTS ACROSS THE WEST HALF OF LAKE
SUPERIOR WITH NORTHWEST WINDS AND COLDER AIR COMING ACROSS LAKE
SUPERIOR. OTHERWISE...NO GALES ARE SEEN AS NO STRONG PRESSURE
SYSTEMS STAY AWAY FROM THE AREA.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 1 AM EST TUESDAY FOR MIZ007-014.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...SRF
AVIATION...KC
MARINE...07
AREA FORECAST DISCUSSION
NWS BILLINGS MT
330 PM MST MON DEC 16 2013
.SHORT TERM...VALID FOR TUE AND WED...
MILD AND WINDY WEATHER WILL CONTINUE THROUGH WED BENEATH NORTHWEST
FLOW ALOFT...BUT A SHORT WAVE TROUGH WILL THEN SEND AN ARCTIC COLD
FRONT SOUTH THROUGH THE REGION WITH SNOW BEGINNING WED NIGHT.
TONIGHT...WE HAVE LINGERED SOME LIKELY POPS THROUGH THE EVENING IN
THE BAKER AREA...LARGELY BASED ON RECENT RAP SIMULATIONS WHICH ARE
ABOUT THE ONLY GUIDANCE CAPTURING ONGOING SNOW OVER THAT AREA. THE
SNOW /WHICH WE DID NOT EXPECT TO THIS MAGNITUDE/ APPEARS DRIVEN BY
MID-LEVEL FRONTOGENESIS...WHICH SHOULD ONLY SLOWLY WANE DURING THE
LATE AFTERNOON AND EVENING. OTHERWISE...WINDS WILL INCREASE BEFORE
DAYBREAK AGAIN IN THE LIVINGSTON AND NYE AREAS AS SUBSTANTIAL LEE-
SIDE SURFACE PRESSURE FALLS TAKE SHAPE FROM NORTH CENTRAL MT UP TO
CENTRAL ALBERTA. WE THUS BEGAN A WIND ADVISORY AT 09 UTC FOR THOSE
LOCATIONS. FINALLY...WE GENERALLY HELD LOWS A BIT WARMER THAN WHAT
GUIDANCE WOULD SUGGEST IN MOST PLACES TONIGHT SINCE DEWPOINTS THIS
AFTERNOON HAVE MAINLY STAYED IN THE 20S F. OUR CONFIDENCE IS LOWER
THAN NORMAL THOUGH. ONE EXCEPTION TO THIS METHODOLOGY WAS AT BAKER
WHERE FRESH SNOW COULD ALLOW TEMPERATURES TO FALL QUICKLY.
TUE...A STRONG LOW-LEVEL PRESSURE GRADIENT WILL CONTINUE FOR SOUTH
CENTRAL MT AND CONTINUE TO BE AIDED BY ISALLOBARIC FORCING WITH AN
AXIS OF 5 HPA/3 HOUR SURFACE PRESSURE FALLS NORTHEAST OF THE LOCAL
AREA. THE MAGNITUDE OF MID-LEVEL STABILITY AND 700-HPA WIND SPEEDS
OF 50 KT OVER LIVINGSTON BODE WELL FOR ADVISORY-LEVEL WINDS THANKS
TO A 15-20 HPA SURFACE GRADIENT BETWEEN IDAHO FALLS AND LEWISTOWN.
DOWNSTREAM...MID-LEVEL WINDS ARE CLOSER TO 60 KT FOR HARLOWTON AND
BIG TIMBER...AND LOW-LEVEL LAPSE RATES ARE STEEP ENOUGH TO SUPPORT
60 MPH GUSTS IN THOSE AREAS. THUS...WE ISSUED A WIND ADVISORY OVER
NORTHERN SWEET GRASS COUNTY AND A HIGH WIND WATCH ACROSS SOUTHERN
WHEATLAND COUNTY /WHERE WARNING CRITERIA IS LOWER/ BEGINNING AT 13
UTC TUE. AN IN-HOUSE STATISTICAL METHOD FOR HIGH WINDS IN SOUTHERN
WHEATLAND COUNTY ALSO SUPPORTS 60-65 MPH GUSTS AT HARLOWTON. HIGHS
WILL BE MILD AGAIN TUE...WITH 50+ F READINGS IN SOUTH CENTRAL MT.
TUE NIGHT...STRONG WINDS WILL CONTINUE IN SOUTH CENTRAL MT...SO WE
KEPT HEADLINES GOING. A WELL-MIXED BOUNDARY LAYER MAY KEEP LOWS ON
THE WARM SIDE...EVEN ON THE RIDGETOPS OF SOUTHEASTERN MT.
BY WED...THE LOW-LEVEL PRESSURE GRADIENT WILL BE RELAXING...SO THE
WINDS SHOULD BEGIN DECREASING DURING THE MORNING. ANOTHER MILD DAY
IS IN STORE...AND MUCH LIKE PRIOR DAYS IT/S POSSIBLE THAT GUIDANCE
WILL HAVE A COLD BIAS GIVEN THE RAPIDLY MELTING SNOW FIELD. ON WED
NIGHT...WE HAVE HIGH CONFIDENCE IN AN ARCTIC COLD FRONT PUSHING TO
THE SOUTH ACROSS THE AREA...WITH WIDESPREAD SNOW DEVELOPING BEHIND
THE BOUNDARY PER WELL-CLUSTERED 12 UTC MODEL SOLUTIONS. QG FORCING
ALOFT AND LOW-LEVEL UPSLOPE STRONGLY SUPPORTS A FEW INCHES OF SNOW
OVER MUCH OF THE AREA BY DAYBREAK THU. SCHULTZ
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
SURGE OF ARCTIC AIR THURSDAY MORNING WILL BE CONTINUING TO SUPPORT
SNOWFALL AS A DISTURBANCE SWING THROUGH WESTERN MONTANA. SURFACE
WINDS LOOK TO STAY IN A NORTHEASTERLY ORIENTATION WHICH WILL FAVOR
UPSLOPE EFFECTS AND GENERALLY EXPECT 2 TO 6 INCH SNOWFALL AMOUNTS
ACROSS THE REGION WITH 4 TO 5 INCHES BEING REALLY COMMON. THIS IS
TIMING WITH THE THURSDAY MORNING COMMUTE SO SLICK ROADS AND POOR
VISIBILITY SHOULD BE EXPECTED. SNOW DISSIPATES THURSDAY AFTERNOON
AND EARLY EVENING AS THE ARCTIC HIGH QUICKLY PULLS TO THE
SOUTHEAST AND LEESIDE TROFFING BEGINS ALONG THE FRONT RANGE. THIS
PATTERN MAY CAUSE AN EPISODE OF BLOWING SNOW LATE THURSDAY NIGHT
AND FRIDAY SO WILL HAVE TO WATCH FOR A BIMODAL WINTER THREAT BUT
IT MAY NOT BE CONTINUOUS. TEMPERATURES ON THURSDAY LOOK GO NOWHERE
WITH COLD ADVECTION CONTINUING AND CLOUDS AND SNOW ELIMINATING
HEATING. WILL BE SOME COLD SPOTS THURSDAY NIGHT ACROSS THE EAST
BUT MIXING OVER THE WESTERN ZONES SHOULD LIMIT TEMPERATURES FROM
FALLING BELOW ZERO.
FRIDAY TEMPERATURES ALREADY MODERATING ACROSS THE AREA WITH
WESTERN ZONES TRYING TO APPROACH 30. WINDS WILL BE ON THE INCREASE
FOR GAP FLOW AREAS WITH THIS PATTERN CONTINUING INTO SATURDAY.
FOR SATURDAY AND BEYOND NORTHWEST FLOW ALOFT LOOKS MOIST AND
UNSETTLED WITH A WAFFLING ARCTIC BOUNDARY ACROSS THE REGION.
ANALOGS AND CONFIDENCE TOOLKIT DIAGNOSTICS SHOW IT IS NOT A VERY
WET PATTERN BUT SOME SHOWER ACTIVITY SHOULD BE EXPECTED WITH
MODELS INDICATING A STRONG MOISTURE TAP MOVING INTO THE PACIFIC
NORTHWEST. MODELS ARE ALSO SHOWING A BETTER PUSH OF COLD AIR INTO
SOUTHEAST MONTANA SATURDAY NIGHT AND SUSPECT THAT THIS MAY BE A
RECURRENT THEME THROUGH THE EXTENDED. HAVE ADDED ISOLATED TO
SCATTERED SHOWER ACTIVITY FOR PERIODS SATURDAY AND BEYOND. BORSUM
&&
.AVIATION...
LIGHT SNOW WITH MVFR CONDITIONS WILL PERSIST INVOF KMLS WITH IFR
CONDITIONS TO THE EAST INCLUDING KBHK. VFR CONDITIONS ACROSS
WESTERN AREAS WITH GUSTY WINDS ALONG THE FOOTHILLS. EXPECT WINDS
TO BECOME EVEN STRONGER AFTER MIDNIGHT TONIGHT. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
TUE WED THU FRI SAT SUN MON
-----------------------------------------------------------
BIL 026/052 033/047 010/014 002/028 017/030 019/039 026/040
00/N 02/R 88/S 12/J 32/J 22/J 22/J
LVM 032/049 034/048 012/016 004/028 019/031 024/037 028/040
00/N 02/R 88/S 22/J 32/J 22/J 22/J
HDN 020/055 029/048 007/014 908/027 009/029 009/038 018/041
00/B 02/R 88/S 11/B 22/J 22/J 22/J
MLS 020/040 026/042 002/008 910/019 002/020 009/031 018/037
10/B 02/R 88/S 11/B 12/J 22/J 22/J
4BQ 019/047 025/048 005/014 908/024 006/025 012/038 021/042
10/B 00/B 58/S 11/B 22/J 22/J 22/J
BHK 017/038 022/039 002/008 908/018 004/019 006/028 019/036
60/B 01/B 78/S 10/B 12/J 22/J 22/J
SHR 023/051 027/050 008/016 906/025 009/029 012/037 018/043
00/B 01/B 58/S 11/B 22/J 22/J 22/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...HIGH WIND WATCH IN EFFECT FROM TUESDAY MORNING THROUGH
WEDNESDAY MORNING FOR ZONE 28.
WIND ADVISORY IN EFFECT FROM 6 AM TUESDAY TO NOON MST
WEDNESDAY FOR ZONE 41.
WIND ADVISORY IN EFFECT FROM 2 AM TUESDAY TO NOON MST
WEDNESDAY FOR ZONES 65-66.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1132 AM CST MON DEC 16 2013
.UPDATE...
ISSUED AT 1035 AM CST MON DEC 16 2013
AFTER A RELATIVELY MILD START TO THE MORNING...TEMPERATURES ARE
WARMING RAPIDLY...AIDED IN PART BY CLEAR SKIES AND A DOWNSLOPING
COMPONENT TO THE LOW LEVEL WIND. FOR THIS AFTERNOON...MODEL GUIDANCE
CONTINUES TO INDICATE COOLING IN MID LEVELS ATOP THE REGION TODAY
AS A WAVE ADVANCES SOUTHEAST FROM THE CANADIAN PRAIRIES INTO THE
GREAT LAKES REGION. BUT DESPITE THE COOLING ALOFT...LITTLE IMPACT
ON THE SURFACE TEMPERATURES IS ANTICIPATED. IN FACT WILL PUSH UP
HIGHS SLIGHTLY ACROSS OUR NORTH AS KONL AND KANW HAVE ALREADY
ECLIPSED 40F AS OF 10 AM THIS MORNING.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CST MON DEC 16 2013
TODAY AND TONIGHT...A POWERFUL THERMAL RIDGE WILL CONTINUE OPERATING
ACROSS THE FORECAST AREA. A WEAK COLD FRONT ACROSS SERN MT THIS
MORNING COULD DROP THROUGH THE NERN PORTION OF THE FCST AREA THIS
AFTERNOON BUT TEMPS BEHIND THE FRONT ARE ABOVE FREEZING SO NO
SIGNIFICANT COOLING IS EXPECTED. THE TEMPERATURE FCST TODAY FOLLOWS
THE WARMEST MODELS WHICH ARE THE HRRR AND RAP FORECASTING MID TO
UPPER 50S ACROSS SWRN NEB. THESE MODELS HAVE VERIFIED THE BEST OVER
THE WEEKEND. 40S ARE EXPECTED ACROSS THE SNOW COVER NORTH AND THIS
SNOW IS MELTING.
WINDS AT H850 MB CONTINUE AT 30 TO 40 KT TODAY WITH 500M AGL WINDS
OF 20 TO 25 KTS. THIS WOULD PRODUCE 15 TO 25 MPH WINDS AT THE SFC.
THE MID LEVEL CLOUD SHIELD ACROSS WRN SD AND ERN MT IS EXPECTED TO
SLICE THROUGH THE NERN PORTION OF THE FCST AREA TODAY WITH SCT-BKN
CIRRUS SOUTH AND WEST.
HIGH CLOUDS ARE EXPECTED TONIGHT AND THE NAM SUGGESTED MID LEVEL
CLOUDS NORTH AND EAST. ALL OF THESE CLOUDS SHOULD LIMIT RADIATIONAL
COOLING AND THE BEST GUESS WITH LOWS TONIGHT IS 20S WITH UPPER 20S
UNDER THE MID LEVEL CLOUD DECK. H850 MB WINDS WEAKEN TO 10 TO 25 KTS
WEST WHICH WOULD SUPPORT MODEST RADIATIONAL COOLING DESPITE THE
CLOUD COVER. 30 TO 40KT H850 WINDS CONTINUE NORTH AND EAST
SUPPORTING THE WARMER LOWS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 356 AM CST MON DEC 16 2013
PRIMARY FORECAST CONCERNS DEAL WITH TEMPERATURES THE NEXT SEVERAL
DAYS...THEN TURNS TO STRONG FRONTAL PASSAGE THURSDAY WITH COLDER
TEMPERATURES AND POSSIBLY SNOW FOR PARTS OF THE AREA.
RIDGING ALOFT WILL BUILD OVER THE CENTRAL PLAINS ON TUESDAY IN THE
WAKE OF AN UPPER LEVEL SHORTWAVE TROUGH. STILL EXPECT TO SEE AN
INFLUENCE ON TEMPERATURES OVER THE NORTHERN PARTS OF NEBRASKA FROM
THE SNOWPACK...HOWEVER WITH TEMPERATURES RISING ABOVE FREEZING
SHOULD CONTINUE TO SEE THE SNOW MELT IN THE COMING DAYS. DO HAVE A
WARMING TREND FOR THE SNOWPACK LOCATIONS...HOWEVER DIDN/T GO TOO
WARM YET UNTIL START TO SEE MUCH LESS INFLUENCE FROM THE SNOW. WHERE
THE GROUND IS DRY...LOOKING AT HIGHS 10 TO 15 DEGREES WARMER IN THE
50S TO NEAR 60 ON TUESDAY.
THE UPPER LEVEL LOW CURRENTLY OVER ALASKA...AS WELL AS THE UPPER LOW
OFF THE CALIFORNIA COAST WILL BOTH MAKE THEIR WAY ONTO THE WEST
COAST TUESDAY NIGHT AND WEDNESDAY. THESE TWO SYSTEMS WILL STAY
SEPARATE...BUT WILL BOTH WORK TO DEEPEN THE TROUGH ACROSS THE
WESTERN CONUS. AS THIS OCCURS...THE THERMAL RIDGE WILL STRENGTHEN
WITH 850MB TEMPERATURES NEARING 16C. DID INCREASE LOWS FOR TUESDAY
NIGHT DUE TO THE WARMING EXPECTED...HOWEVER WITH FAIRLY LIGHT WINDS
AND DEWPOINTS IN THE UPPER TEENS AND LOW 20S...MAY STILL GET
TEMPERATURES TO FALL INTO THE MID AND UPPER 20S. THIS PERIOD MAY
NEED TO BE ADJUSTED IN COMING FORECASTS. THEN FOR WEDNESDAY...SOME
PORTIONS OF SOUTHWEST NEBRASKA SHOULD APPROACH OR EXCEED 60 DEGREES.
AGAIN...AREAS ACROSS THE NORTH ARE QUESTIONABLE DUE TO THE SNOWPACK.
WILL SEE HOW THE NEXT COUPLE OF DAYS MELT THE SNOW AND WILL ADJUST
HIGHS IN THESE AREAS AS NEEDED. WINDS LOOK TO BE PRETTY LIGHT ON
WEDNESDAY TO LIMIT THE MIXING WITH MODELS ONLY MIXING TO 850MB OR
LOWER. IF DEEPER MIXING CAN BE REALIZED TEMPERATURES WILL BE TOO LOW
AND NEED TO BE ADJUSTED UPWARDS. FOR EXAMPLE...AT LBF MIXING TO
850MB WEDNESDAY AFTERNOON WOULD BRING A HIGH OF 64 DEGREES.
IS SOME DIFFERENCES ON TIMING OF THE ARCTIC FRONT ON
THURSDAY...WHICH THEN TRANSLATES TO LOWER CONFIDENCE ON HIGHS.
LOOKING AT THE 16.00Z MODELS...THE OPERATIONAL GFS HAS STAYED FAIRLY
SIMILAR IN TIMING WHICH IS THE COLDEST SOLUTION. THIS WOULD SUGGEST
HIGHS FROM THE UPPER TEENS OVER NORTH CENTRAL NEBRASKA TO THE MID
30S IN THE SOUTHWEST. HOWEVER THE GFS ENSEMBLES ARE SHOWING A
VARIETY OF SOLUTIONS AS IT SHOWS A DIFFERENCE OF 5 STANDARD
DEVIATIONS FOR MUCH OF THE FORECAST WHICH TRANSLATES TO A 20 DEGREE
DIFFERENCE AMONG JUST THE GFS SOLUTIONS. THE ECMWF DID SPEED THE
FRONT UP SLIGHTLY WITH THE 16.00Z RUN...HOWEVER THE GEM SLOWED IT
DOWN. WITH THE WIDE VARIETY OF SOLUTIONS AND LOWER CONFIDENCE WILL
KEEP THE FORECAST FAIRLY SIMILAR TO THE ONGOING FORECAST UNTIL THERE
IS BETTER SUPPORT TO GO COLDER.
IT DOES CONTINUE TO LOOK LIKE THERE WILL BE SOME POST-FRONTAL
PRECIPITATION...HOWEVER IT LOOKS LIKE VERY LIGHT PRECIPITATION. IN
THE UPPER LEVEL PATTERN...THE UPPER LOW NOW OFF THE CALIFORNIA COAST
WILL MOVE ACROSS THE CENTRAL PLAINS JUST AHEAD OF THE ARCTIC FRONT
/WITH LITTLE OR NO IMPACT IN THE SENSIBLE WEATHER/...AND WITH THE
WEST COAST SYSTEM DIGGING INTO SOUTHERN CALIFORNIA ON
THURSDAY...THERE ISN/T A GOOD MOISTURE FEED INTO THE AREA AS THE
ARCTIC FRONT PASSES. THIS WILL LEAD TO A DISJOINTED ATTEMPT AT
PRECIPITATION AS LIFT IS NOT IN THE AREA WHEN THE COLUMN SEES THE
GREATEST AMOUNT OF MOISTURE...WHILE THE MODELS ARE ALSO SHOWING A
DRY LAYER AROUND 700MB TO ALSO INHIBIT PRECIPITATION. CURRENT
FORECAST LIMITS THE PRECIPITATION TO MAINLY THE NORTHWEST HALF OF
THE FORECAST AREA. HAVE BEEN WATCHING A SIGNAL FOR DRIZZLE ON
THURSDAY OVER THE PAST FEW DAYS...AND ALTHOUGH SOUNDINGS WON/T
DISCOUNT IT RIGHT NOW WITH THE DRY LAYER EXPECTED...THEY ARE ALSO
SHOWING ENOUGH DRY AIR RIGHT AT THE SURFACE WHICH MAY KEEP ANY
DRIZZLE FROM BEING A THREAT. THEN AS THE COLUMN COOLS FURTHER WITH
THE COLD AIR INTRUSION...AND THE DRY LAYER GOES AWAY...DRIZZLE
POTENTIAL WILL DIMINISH WITH ONLY SNOW CHANCES. WILL CONTINUE TO
KEEP THE DRIZZLE MENTION OUT OF THE FORECAST FOR NOW AND WATCH IN
THE COMING DAYS.
BEYOND THURSDAY NIGHT THE MODELS ARE TRYING TO KICK OUT THE COLD AIR
TO BRING MORE SEASONABLE TEMPERATURES TO THE FORECAST AREA INTO NEXT
WEEKEND. HOWEVER...THE GFS ENSEMBLE MEMBERS ARE ALL OVER THE BOARD
WITH STANDARD DEVIATIONS OF 5 TO 7 ON HIGHS AND LOWS FRIDAY THROUGH
SUNDAY SO CONFIDENCE IS NOT REAL HIGH AT THIS POINT ON TEMPERATURES
THROUGH THAT TIME FRAME AND HAVE USED A CONSENSUS APPROACH FOR THE
FORECAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1132 AM CST MON DEC 16 2013
VFR TO PREVAIL ACROSS ALL WESTERN AND NORTH CENTRAL NEBRASKA TERMINALS
THROUGH THE 18Z TAF ISSUANCE PERIOD. OTHERWISE BREEZY
NORTHWESTERLY WINDS WILL CONTINUE THIS AFTERNOON FOR MUCH OF THE
REGION...BUT SHOULD WEAKEN THIS EVENING AS THE ATMOSPHERE
DECOUPLES. AT KVTN...A WEAK BOUNDARY WILL HELP KEEP THE LOWER
TROPOSPHERE MIXED THIS EVENING...WITH WIND GUST POTENTIAL OF UP TO
18KTS THROUGH 05Z. THE ONLY OTHER CONCERN TO THE AVIATION COMMUNITY
IS THAT GUIDANCE IS PEGGING AN AREA OF 25KT LOW LEVEL WIND SHEAR
OVERNIGHT ACROSS NORTH CENTRAL NEBRASKA /INCLUDING KVTN/. BUT WILL
NOT INCLUDE A MENTION OF WS IN THE OFFICIAL TAF FOR NOW AS VALUES
FALL BELOW ISSUANCE CRITERIA...WILL CONTINUE TO MONITOR.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JACOBS
SHORT TERM...CDC
LONG TERM...BROOKS
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1036 AM CST MON DEC 16 2013
.UPDATE...
ISSUED AT 1035 AM CST MON DEC 16 2013
AFTER A RELATIVELY MILD START TO THE MORNING...TEMPERATURES ARE
WARMING RAPIDLY...AIDED IN PART BY CLEAR SKIES AND A DOWNSLOPING
COMPONENT TO THE LOW LEVEL WIND. FOR THIS AFTERNOON...MODEL GUIDANCE
CONTINUES TO INDICATE COOLING IN MID LEVELS ATOP THE REGION TODAY
AS A WAVE ADVANCES SOUTHEAST FROM THE CANADIAN PRAIRIES INTO THE
GREAT LAKES REGION. BUT DESPITE THE COOLING ALOFT...LITTLE IMPACT
ON THE SURFACE TEMPERATURES IS ANTICIPATED. IN FACT WILL PUSH UP
HIGHS SLIGHTLY ACROSS OUR NORTH AS KONL AND KANW HAVE ALREADY
ECLIPSED 40F AS OF 10 AM THIS MORNING.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CST MON DEC 16 2013
TODAY AND TONIGHT...A POWERFUL THERMAL RIDGE WILL CONTINUE OPERATING
ACROSS THE FORECAST AREA. A WEAK COLD FRONT ACROSS SERN MT THIS
MORNING COULD DROP THROUGH THE NERN PORTION OF THE FCST AREA THIS
AFTERNOON BUT TEMPS BEHIND THE FRONT ARE ABOVE FREEZING SO NO
SIGNIFICANT COOLING IS EXPECTED. THE TEMPERATURE FCST TODAY FOLLOWS
THE WARMEST MODELS WHICH ARE THE HRRR AND RAP FORECASTING MID TO
UPPER 50S ACROSS SWRN NEB. THESE MODELS HAVE VERIFIED THE BEST OVER
THE WEEKEND. 40S ARE EXPECTED ACROSS THE SNOW COVER NORTH AND THIS
SNOW IS MELTING.
WINDS AT H850 MB CONTINUE AT 30 TO 40 KT TODAY WITH 500M AGL WINDS
OF 20 TO 25 KTS. THIS WOULD PRODUCE 15 TO 25 MPH WINDS AT THE SFC.
THE MID LEVEL CLOUD SHIELD ACROSS WRN SD AND ERN MT IS EXPECTED TO
SLICE THROUGH THE NERN PORTION OF THE FCST AREA TODAY WITH SCT-BKN
CIRRUS SOUTH AND WEST.
HIGH CLOUDS ARE EXPECTED TONIGHT AND THE NAM SUGGESTED MID LEVEL
CLOUDS NORTH AND EAST. ALL OF THESE CLOUDS SHOULD LIMIT RADIATIONAL
COOLING AND THE BEST GUESS WITH LOWS TONIGHT IS 20S WITH UPPER 20S
UNDER THE MID LEVEL CLOUD DECK. H850 MB WINDS WEAKEN TO 10 TO 25 KTS
WEST WHICH WOULD SUPPORT MODEST RADIATIONAL COOLING DESPITE THE
CLOUD COVER. 30 TO 40KT H850 WINDS CONTINUE NORTH AND EAST
SUPPORTING THE WARMER LOWS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 356 AM CST MON DEC 16 2013
PRIMARY FORECAST CONCERNS DEAL WITH TEMPERATURES THE NEXT SEVERAL
DAYS...THEN TURNS TO STRONG FRONTAL PASSAGE THURSDAY WITH COLDER
TEMPERATURES AND POSSIBLY SNOW FOR PARTS OF THE AREA.
RIDGING ALOFT WILL BUILD OVER THE CENTRAL PLAINS ON TUESDAY IN THE
WAKE OF AN UPPER LEVEL SHORTWAVE TROUGH. STILL EXPECT TO SEE AN
INFLUENCE ON TEMPERATURES OVER THE NORTHERN PARTS OF NEBRASKA FROM
THE SNOWPACK...HOWEVER WITH TEMPERATURES RISING ABOVE FREEZING
SHOULD CONTINUE TO SEE THE SNOW MELT IN THE COMING DAYS. DO HAVE A
WARMING TREND FOR THE SNOWPACK LOCATIONS...HOWEVER DIDN/T GO TOO
WARM YET UNTIL START TO SEE MUCH LESS INFLUENCE FROM THE SNOW. WHERE
THE GROUND IS DRY...LOOKING AT HIGHS 10 TO 15 DEGREES WARMER IN THE
50S TO NEAR 60 ON TUESDAY.
THE UPPER LEVEL LOW CURRENTLY OVER ALASKA...AS WELL AS THE UPPER LOW
OFF THE CALIFORNIA COAST WILL BOTH MAKE THEIR WAY ONTO THE WEST
COAST TUESDAY NIGHT AND WEDNESDAY. THESE TWO SYSTEMS WILL STAY
SEPARATE...BUT WILL BOTH WORK TO DEEPEN THE TROUGH ACROSS THE
WESTERN CONUS. AS THIS OCCURS...THE THERMAL RIDGE WILL STRENGTHEN
WITH 850MB TEMPERATURES NEARING 16C. DID INCREASE LOWS FOR TUESDAY
NIGHT DUE TO THE WARMING EXPECTED...HOWEVER WITH FAIRLY LIGHT WINDS
AND DEWPOINTS IN THE UPPER TEENS AND LOW 20S...MAY STILL GET
TEMPERATURES TO FALL INTO THE MID AND UPPER 20S. THIS PERIOD MAY
NEED TO BE ADJUSTED IN COMING FORECASTS. THEN FOR WEDNESDAY...SOME
PORTIONS OF SOUTHWEST NEBRASKA SHOULD APPROACH OR EXCEED 60 DEGREES.
AGAIN...AREAS ACROSS THE NORTH ARE QUESTIONABLE DUE TO THE SNOWPACK.
WILL SEE HOW THE NEXT COUPLE OF DAYS MELT THE SNOW AND WILL ADJUST
HIGHS IN THESE AREAS AS NEEDED. WINDS LOOK TO BE PRETTY LIGHT ON
WEDNESDAY TO LIMIT THE MIXING WITH MODELS ONLY MIXING TO 850MB OR
LOWER. IF DEEPER MIXING CAN BE REALIZED TEMPERATURES WILL BE TOO LOW
AND NEED TO BE ADJUSTED UPWARDS. FOR EXAMPLE...AT LBF MIXING TO
850MB WEDNESDAY AFTERNOON WOULD BRING A HIGH OF 64 DEGREES.
IS SOME DIFFERENCES ON TIMING OF THE ARCTIC FRONT ON
THURSDAY...WHICH THEN TRANSLATES TO LOWER CONFIDENCE ON HIGHS.
LOOKING AT THE 16.00Z MODELS...THE OPERATIONAL GFS HAS STAYED FAIRLY
SIMILAR IN TIMING WHICH IS THE COLDEST SOLUTION. THIS WOULD SUGGEST
HIGHS FROM THE UPPER TEENS OVER NORTH CENTRAL NEBRASKA TO THE MID
30S IN THE SOUTHWEST. HOWEVER THE GFS ENSEMBLES ARE SHOWING A
VARIETY OF SOLUTIONS AS IT SHOWS A DIFFERENCE OF 5 STANDARD
DEVIATIONS FOR MUCH OF THE FORECAST WHICH TRANSLATES TO A 20 DEGREE
DIFFERENCE AMONG JUST THE GFS SOLUTIONS. THE ECMWF DID SPEED THE
FRONT UP SLIGHTLY WITH THE 16.00Z RUN...HOWEVER THE GEM SLOWED IT
DOWN. WITH THE WIDE VARIETY OF SOLUTIONS AND LOWER CONFIDENCE WILL
KEEP THE FORECAST FAIRLY SIMILAR TO THE ONGOING FORECAST UNTIL THERE
IS BETTER SUPPORT TO GO COLDER.
IT DOES CONTINUE TO LOOK LIKE THERE WILL BE SOME POST-FRONTAL
PRECIPITATION...HOWEVER IT LOOKS LIKE VERY LIGHT PRECIPITATION. IN
THE UPPER LEVEL PATTERN...THE UPPER LOW NOW OFF THE CALIFORNIA COAST
WILL MOVE ACROSS THE CENTRAL PLAINS JUST AHEAD OF THE ARCTIC FRONT
/WITH LITTLE OR NO IMPACT IN THE SENSIBLE WEATHER/...AND WITH THE
WEST COAST SYSTEM DIGGING INTO SOUTHERN CALIFORNIA ON
THURSDAY...THERE ISN/T A GOOD MOISTURE FEED INTO THE AREA AS THE
ARCTIC FRONT PASSES. THIS WILL LEAD TO A DISJOINTED ATTEMPT AT
PRECIPITATION AS LIFT IS NOT IN THE AREA WHEN THE COLUMN SEES THE
GREATEST AMOUNT OF MOISTURE...WHILE THE MODELS ARE ALSO SHOWING A
DRY LAYER AROUND 700MB TO ALSO INHIBIT PRECIPITATION. CURRENT
FORECAST LIMITS THE PRECIPITATION TO MAINLY THE NORTHWEST HALF OF
THE FORECAST AREA. HAVE BEEN WATCHING A SIGNAL FOR DRIZZLE ON
THURSDAY OVER THE PAST FEW DAYS...AND ALTHOUGH SOUNDINGS WON/T
DISCOUNT IT RIGHT NOW WITH THE DRY LAYER EXPECTED...THEY ARE ALSO
SHOWING ENOUGH DRY AIR RIGHT AT THE SURFACE WHICH MAY KEEP ANY
DRIZZLE FROM BEING A THREAT. THEN AS THE COLUMN COOLS FURTHER WITH
THE COLD AIR INTRUSION...AND THE DRY LAYER GOES AWAY...DRIZZLE
POTENTIAL WILL DIMINISH WITH ONLY SNOW CHANCES. WILL CONTINUE TO
KEEP THE DRIZZLE MENTION OUT OF THE FORECAST FOR NOW AND WATCH IN
THE COMING DAYS.
BEYOND THURSDAY NIGHT THE MODELS ARE TRYING TO KICK OUT THE COLD AIR
TO BRING MORE SEASONABLE TEMPERATURES TO THE FORECAST AREA INTO NEXT
WEEKEND. HOWEVER...THE GFS ENSEMBLE MEMBERS ARE ALL OVER THE BOARD
WITH STANDARD DEVIATIONS OF 5 TO 7 ON HIGHS AND LOWS FRIDAY THROUGH
SUNDAY SO CONFIDENCE IS NOT REAL HIGH AT THIS POINT ON TEMPERATURES
THROUGH THAT TIME FRAME AND HAVE USED A CONSENSUS APPROACH FOR THE
FORECAST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 514 AM CST MON DEC 16 2013
VFR IS EXPECTED ALL AREAS TODAY AND TONIGHT.
SCT-BKN MID AND HIGH LEVEL CLOUDS WILL CONTINUE MOVING SOUTHEAST
THROUGH THE REGION.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JACOBS
SHORT TERM...CDC
LONG TERM...BROOKS
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
309 PM EST MON DEC 16 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL TRACK FROM THE UPPER OHIO VALLEY TO
OFF THE NEW JERSEY COAST BY TUESDAY AFTERNOON. THIS LOW WILL BRING
A LIGHT SNOWFALL TO MUCH OF CENTRAL NEW YORK AND A MODERATE
SNOWFALL TO PARTS OF NORTHEAST PENNSYLVANIA AND THE CATSKILLS FROM
LATE TONIGHT THROUGH TUESDAY. AFTER THIS LOW PASSES BY...COLD AIR
WILL REMAIN ACROSS THE REGION THROUGH WEDNESDAY WITH MORE LAKE
EFFECT SNOW SHOWERS AND FLURRIES. MUCH MILDER AIR WILL BEGIN TO
RETURN TO THE REGION BY THE END OF THE WEEK AS A SOUTHWESTERLY
FLOW OF AIR BECOMES ESTABLISHED ACROSS THE EASTERN UNITED STATES.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
SINGLE SHORELINE LAKE EFFECT SNOW BAND OFF LAKE ONTARIO HAS NOW
SHIFTED INLAND AND WAS BREAKING UP INTO MULTIPLE BANDS OF LESS
ORGANIZED SNOW SHOWERS AND FLURRIES. RAP MODEL SOUNDINGS SHOW A
PRONOUNCED SHIFT TO NW FLOW UNDER THE INVERSION AT 18-19Z AND
INDEED THE KTYX 88D SHOWS A NW FLO ARND 340 DEGREES AT 3000 FEET
AGL. IN ADDTN...SUBSDC WILL CONT TO PUSH THE INVERSION DOWN WHICH
AS PER MODEL SOUNDINGS IS PROJECTED TO DROP TO ARND 3000 FEET AGL
FROM 7000 FEET AGL AT PRESENT. BY 00 TO 01Z...THE LL FLOW BACKS TO
THE SW. THIS IN EFFECT WILL CUT OFF THE LES SNOWS AND FLURRIES BY
03Z THE LATEST. FOR ACCUMULATIONS...I CAN SEE ANTHR 1-2 INCHES
BTWN SYR AND CORTLAND IN THE HIGHLANDS OF CENTRAL NY. REST OF CWA
WILL SEE PC SKIES THIS AFTERNOON WITH SCATTERED FLURRIES AS THE
TEMPERATURES IN THE BNDRY LAYER UNDER THE INVERSION WERE IN THE
MAXIMUM ZONE OF ICE CRYSTAL FORMATION ARND -12C TO 15C (AT 1000 MB
MAX GROWTH IS -12C). HENCE FLOW OVER THE HILLS AND EVEN A LITTLE
CONVECTIVE OVERTURNING IN SC CLDS WILL SPIT OUT SOME FLURRIES.
FARTHER AWAY FROM THE LAKES IN NE PA...WHERE BNDRY LAYER WAS
DRIER...FLURRIES WERE SUBLIMATING SO HAVE NO POPS THERE.
AFTER SUNSET...WITH THE LOSS OF THE SFC HEATING AND THE LL FLOW
TURNING MORE W-SW...SKIES SHUD CLR AND THE LES ACVTY WILL END AS
STATED ABV. I SEE RAPID COOLING IN THE BNDRY LAYER...UNTIL HIGHER
CLDS BEGIN ARRIVING FROM THE SW BTWN 6 AND 9Z AHEAD OF CLIPPER
SYSTEM. I HAVE SOME LIGHT SNOWS AND FLURRIES ARRIVING FROM 9Z TO
12Z ACRS ENTIRE FORECAST AREA FROM APPROACHING CLIPPER SYSTEM. SO
I HAVE ADDED POPS LATE.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
ISSUED WINTER WEATHER ADVY FOR TUESDAY FROM 5 AM TO 5 PM FOR THE
APPROACHING CLIPPER-LIKE SYSTEM. ALL SYNOPTIC AND MESOSCALE MODELS
SHOW A DECENT SHOT OF SIGNIFICANT WAA/ISEN LIFT WITH ENUF MOISTURE
TO SQUEEZE OUT AT LEAST .1 TO .2 INCHES OF QPF...WITH POTENTIALLY A
LITTLE MORE ACRS PIKE/SULLIVAN CO/S. ASSUMING A 15 TO 1 SNOW TO
QPF RATIO I CAN SEE ARND 3-5 INCHES IN THESE TWO COUNTIES WHICH
MEETS OUR ADVY CRITERIA OF 4 INCHES/12 HOURS. SO IN COLLABORATION
WITH SURROUNDING OFFICES WE ISSUED A WW ADVY FOR SNOW. WPC WWD
GRAPHIC ALSO IN LINE SHOWING A SMALL AREA OF 4-6 INCHES IN
SULLIVAN/PIKE CO/S. REST OF CWA WE FEEL WILL SEE MAINLY 1-3
INCHES. WILL MENTION IN HWO AS ROADS LIKELY WILL BE HAZARDOUS TO
SOME EXTENT TUE AM FOR REST OF FORECAST AREA.
AFTER THIS SYSTEM PASSES BY...AN UPR LVL TROF WILL PUSH SOUTHEAST
ACRS THE REGION WITH MODEST CAA. I KEPT CHC SN SHOWERS/FLURRIES IN
AS SOME LAKE EFFECT MOISTURE WILL CONT TO STREAM INTO C NY AND NRN
PA UNDER THIS COLDER AIR ALOFT. HIGHEST POPS AND AMNTS WILL BE IN OUR
FAR NRN COUNTIES DIRECTLY DOWNWIND OF LAKE ONTARIO. MAY NEED TO
CONSIDER LES ADVYS LATER IN THIS PERIOD FOR MAINLY WEDNESDAY.
THEN FOR WED NGT SOME WAA KICKS IN COINCIDENT WITH RISING HGHTS SO
THERE LIKELY WILL BE SOME LIMITED AMNTS OF LIFTG TO SUPPORT JUST A
CHC POPS FOR SN SHOWERS/FLURRIES.
THEN FOR THURSDAY...SW FLO SETS UP IN EARNEST AS TEMPS BEGIN TO
SOAR AT 850 MB. THIS WILL CUT OFF ALL LAKE EFFECT MOISTURE AND
START A TURN TO MUCH MILDER WX FOR OUR REGION.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
MEDIUM RANGE MODELS ARE NOW IN MUCH BETTER AGREEMENT DURING THIS
ACTIVE EXTENDED FORECAST PERIOD. THE UPPER LEVEL PATTERN WILL
FEATURE A DEEP WESTERN TROF AND STRONG SOUTHEAST RIDGE THAT WILL
PROVIDE A FAIRLY MILD DEEP SOUTHWEST FLOW ACROSS THE NORTHEAST.
AT THE SFC, THURSDAY NIGHT THROUGH FRIDAY NIGHT, SFC LOW PRES WILL
TRACK FROM THE MID WEST NORTHEAST ACROSS THE UPPER GREAT LAKES
THEN EAST ACROSS NEARBY SOUTHERN CANADA. AS THIS SYSTEM PASSES TO
OUR WEST WARM AIR WILL OVERSPREAD THE AREA BRINGING MAINLY RAIN
SHOWERS ON FRIDAY. FRIDAY NIGHT THE TRAILING COLD FRONT IS EXPECTED
TO CROSS THE AREA WITH MIXED RAIN/SNOW SHOWERS POSSIBLE.
SATURDAY MAY BE MAINLY DRY AS SFC HIGH PRES BRIEFLY BUILDS SOUTH
OVER THE NORTHEAST. SATURDAY NIGHT THROUGH SUNDAY NIGHT, ANOTHER
LOW PRES SYSTEM WILL MOVE NORTHEAST ALONG THIS STALLED BOUNDARY
AND INTO THE NORTHEAST. A STRONG THERMAL GRADIENT WILL RESIDE OVER
THE REGION THEREFORE DETERMINING P-TYPE WILL BE VERY DIFFICULT. FOR
NOW WILL MENTION BOTH RAIN/SNOW. CURRENT TREND IS FOR A WARMER
SOLUTION SO THIS SECOND WAVE COULD BE ASSOCIATED WITH SIGNIFICANT
RAINFALL. STILL MUCH TO BE DETERMINED.
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
A WEAK SFC TROF IS PASSING THROUGH THE REGION THIS AFTERNOON WITH
WIDESPREAD FLURRIES AND OCCASIONAL MVFR CONDITIONS. AT KSYR, A
BETTER DEFINED LAKE SNOW BAND WILL BRING OCCASIONAL IFR CONDITIONS
THROUGH 22Z. BY THIS EVENING WEAK FLOW AND SOME LOW LEVEL DRYING
SHOULD RESULT IN VFR CONDITIONS FOR MUCH OF THE OVERNIGHT PERIOD.
A SYSTEM PASSING TO OUR SOUTH WILL SPREAD IFR/MVFR SNOW ACROSS THE
TERMINALS BEGINNING 10Z-12Z. THE LOWER RESTRICTIONS ARE EXPECTED
OVER THE SRN/CNTRL TERMINALS.
NORTHWEST WINDS AT 1O KNOTS WITH GUST AROUND 18 KNOTS BECOMING LIGHT
THIS EVENING THEN SOUTHEAST AT 5-10 KNOTS ON TUESDAY.
OUTLOOK...
TUESDAY THROUGH WEDNESDAY...RESTRICTIONS POSSIBLE FROM SNOW
SHOWERS.
WEDNESDAY NIGHT THROUGH THURSDAY...BECOMING VFR.
THURSDAY NIGHT THROUGH SATURDAY...RESTRICTIONS POSSIBLE IN RAIN/SNOW
SHOWERS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY FROM 5 AM TO 5 PM EST TUESDAY FOR
PAZ048.
NY...WINTER WEATHER ADVISORY FROM 5 AM TO 5 PM EST TUESDAY FOR
NYZ062.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN
SHORT TERM...DJN
LONG TERM...RRM
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
224 PM EST MON DEC 16 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL TRACK FROM THE UPPER OHIO VALLEY TO
OFF THE NEW JERSEY COAST BY TUESDAY AFTERNOON. THIS LOW WILL BRING
A LIGHT SNOWFALL TO MUCH OF CENTRAL NEW YORK AND A MODERATE
SNOWFALL TO PARTS OF NORTHEAST PENNSYLVANIA AND THE CATSKILLS FROM
LATE TONIGHT THROUGH TUESDAY. AFTER THIS LOW PASSES BY...COLD AIR
WILL REMAIN ACROSS THE REGION THROUGH WEDNESDAY WITH MORE LAKE
EFFECT SNOW SHOWERS AND FLURRIES. MUCH MILDER AIR WILL BEGIN TO
RETURN TO THE REGION BY THE END OF THE WEEK AS A SOUTHWESTERLY
FLOW OF AIR BECOMES ESTABLISHED ACROSS THE EASTERN UNITED STATES.
&&
.NEAR TERM /THROUGH TONIGHT/...
SINGLE SHORELINE LAKE EFFECT SNOW BAND OFF LAKE ONTARIO HAS NOW
SHIFTED INLAND AND WAS BREAKING UP INTO MULTIPLE BANDS OF LESS
ORGANIZED SNOW SHOWERS AND FLURRIES. RAP MODEL SOUNDINGS SHOW A
PRONOUNCED SHIFT TO NW FLOW UNDER THE INVERSION AT 18-19Z AND
INDEED THE KTYX 88D SHOWS A NW FLO ARND 340 DEGREES AT 3000 FEET
AGL. IN ADDTN...SUBSDC WILL CONT TO PUSH THE INVERSION DOWN WHICH
AS PER MODEL SOUNDINGS IS PROJECTED TO DROP TO ARND 3000 FEET AGL
FROM 7000 FEET AGL AT PRESENT. BY 00 TO 01Z...THE LL FLOW BACKS TO
THE SW. THIS IN EFFECT WILL CUT OFF THE LES SNOWS AND FLURRIES BY
03Z THE LATEST. FOR ACCUMULATIONS...I CAN SEE ANTHR 1-2 INCHES
BTWN SYR AND CORTLAND IN THE HIGHLANDS OF CENTRAL NY. REST OF CWA
WILL SEE PC SKIES THIS AFTERNOON WITH SCATTERED FLURRIES AS THE
TEMPERATURES IN THE BNDRY LAYER UNDER THE INVERSION WERE IN THE
MAXIMUM ZONE OF ICE CRYSTAL FORMATION ARND -12C TO 15C (AT 1000 MB
MAX GROWTH IS -12C). HENCE FLOW OVER THE HILLS AND EVEN A LITTLE
CONVECTIVE OVERTURNING IN SC CLDS WILL SPIT OUT SOME FLURRIES.
FARTHER AWAY FROM THE LAKES IN NE PA...WHERE BNDRY LAYER WAS
DRIER...FLURRIES WERE SUBLIMATING SO HAVE NO POPS THERE.
AFTER SUNSET...WITH THE LOSS OF THE SFC HEATING AND THE LL FLOW
TURNING MORE W-SW...SKIES SHUD CLR AND THE LES ACVTY WILL END AS
STATED ABV. I SEE RAPID COOLING IN THE BNDRY LAYER...UNTIL HIGHER
CLDS BEGIN ARRIVING FROM THE SW BTWN 6 AND 9Z AHEAD OF CLIPPER
SYSTEM. I HAVE SOME LIGHT SNOWS AND FLURRIES ARRIVING FROM 9Z TO
12Z ACRS ENTIRE FORECAST AREA FROM APPROACHING CLIPPER SYSTEM. SO
I HAVE ADDED POPS LATE.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
XPCT SCT -SHSN TO PREVAIL ON TUE NGT WITH A SFC TROF IN THE
VCNTY...AIDED BY ANOTHER S/WV. IT APPEARS THAT LES SNOWS WILL DVLP
ON WED AS THE SFC TROF DEPARTS AND FLOW BCMS MORE WRLY. ACTIVITY
SHUD BE FAIRLY SHORT LIVED AS WINDS COME ARND TO THE SW WED EVNG
AS LOW PRES MOVS INTO THE CNTRL GTLAKES.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
MEDIUM RANGE MODELS ARE NOW IN MUCH BETTER AGREEMENT DURING THIS
ACTIVE EXTENDED FORECAST PERIOD. THE UPPER LEVEL PATTERN WILL
FEATURE A DEEP WESTERN TROF AND STRONG SOUTHEAST RIDGE THAT WILL
PROVIDE A FAIRLY MILD DEEP SOUTHWEST FLOW ACROSS THE NORTHEAST.
AT THE SFC, THURSDAY NIGHT THROUGH FRIDAY NIGHT, SFC LOW PRES WILL
TRACK FROM THE MID WEST NORTHEAST ACROSS THE UPPER GREAT LAKES
THEN EAST ACROSS NEARBY SOUTHERN CANADA. AS THIS SYSTEM PASSES TO
OUR WEST WARM AIR WILL OVERSPREAD THE AREA BRINGING MAINLY RAIN
SHOWERS ON FRIDAY. FRIDAY NIGHT THE TRAILING COLD FRONT IS EXPECTED
TO CROSS THE AREA WITH MIXED RAIN/SNOW SHOWERS POSSIBLE.
SATURDAY MAY BE MAINLY DRY AS SFC HIGH PRES BRIEFLY BUILDS SOUTH
OVER THE NORTHEAST. SATURDAY NIGHT THROUGH SUNDAY NIGHT, ANOTHER
LOW PRES SYSTEM WILL MOVE NORTHEAST ALONG THIS STALLED BOUNDARY
AND INTO THE NORTHEAST. A STRONG THERMAL GRADIENT WILL RESIDE OVER
THE REGION THEREFORE DETERMINING P-TYPE WILL BE VERY DIFFICULT. FOR
NOW WILL MENTION BOTH RAIN/SNOW. CURRENT TREND IS FOR A WARMER
SOLUTION SO THIS SECOND WAVE COULD BE ASSOCIATED WITH SIGNIFICANT
RAINFALL. STILL MUCH TO BE DETERMINED.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
A WEAK SFC TROF IS PASSING THROUGH THE REGION THIS AFTERNOON WITH
WIDESPREAD FLURRIES AND OCCASIONAL MVFR CONDITIONS. AT KSYR, A
BETTER DEFINED LAKE SNOW BAND WILL BRING OCCASIONAL IFR CONDITIONS
THROUGH 22Z. BY THIS EVENING WEAK FLOW AND SOME LOW LEVEL DRYING
SHOULD RESULT IN VFR CONDITIONS FOR MUCH OF THE OVERNIGHT PERIOD.
A SYSTEM PASSING TO OUR SOUTH WILL SPREAD IFR/MVFR SNOW ACROSS THE
TERMINALS BEGINNING 10Z-12Z. THE LOWER RESTRICTIONS ARE EXPECTED
OVER THE SRN/CNTRL TERMINALS.
NORTHWEST WINDS AT 1O KNOTS WITH GUST AROUND 18 KNOTS BECOMING LIGHT
THIS EVENING THEN SOUTHEAST AT 5-10 KNOTS ON TUESDAY.
OUTLOOK...
TUESDAY THROUGH WEDNESDAY...RESTRICTIONS POSSIBLE FROM SNOW
SHOWERS.
WEDNESDAY NIGHT THROUGH THURSDAY...BECOMING VFR.
THURSDAY NIGHT THROUGH SATURDAY...RESTRICTIONS POSSIBLE IN RAIN/SNOW
SHOWERS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN
SHORT TERM...
LONG TERM...RRM
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
145 PM EST MON DEC 16 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL TRACK FROM THE UPPER OHIO VALLEY TO
OFF THE NEW JERSEY COAST BY TUESDAY AFTERNOON. THIS LOW WILL BRING
A LIGHT SNOWFALL TO MUCH OF CENTRAL NEW YORK AND A MODERATE
SNOWFALL TO PARTS OF NORTHEAST PENNSYLVANIA AND THE CATSKILLS FROM
LATE TONIGHT THROUGH TUESDAY. AFTER THIS LOW PASSES BY...COLD AIR
WILL REMAIN ACROSS THE REGION THROUGH WEDNESDAY WITH MORE LAKE
EFFECT SNOW SHOWERS AND FLURRIES. MUCH MILDER AIR WILL BEGIN TO
RETURN TO THE REGION BY THE END OF THE WEEK AS A SOUTHWESTERLY
FLOW OF AIR BECOMES ESTABLISHED ACROSS THE EASTERN UNITED STATES.
&&
.NEAR TERM /THROUGH TONIGHT/...
SINGLE SHORELINE LAKE EFFECT SNOW BAND OFF LAKE ONTARIO HAS NOW
SHIFTED INLAND AND WAS BREAKING UP INTO MULTIPLE BANDS OF LESS
ORGANIZED SNOW SHOWERS AND FLURRIES. RAP MODEL SOUNDINGS SHOW A
PRONOUNCED SHIFT TO NW FLOW UNDER THE INVERSION AT 18-19Z AND
INDEED THE KTYX 88D SHOWS A NW FLO ARND 340 DEGREES AT 3000 FEET
AGL. IN ADDTN...SUBSDC WILL CONT TO PUSH THE INVERSION DOWN WHICH
AS PER MODEL SOUNDINGS IS PROJECTED TO DROP TO ARND 3000 FEET AGL
FROM 7000 FEET AGL AT PRESENT. BY 00 TO 01Z...THE LL FLOW BACKS TO
THE SW. THIS IN EFFECT WILL CUT OFF THE LES SNOWS AND FLURRIES BY
03Z THE LATEST. FOR ACCUMULATIONS...I CAN SEE ANTHR 1-2 INCHES
BTWN SYR AND CORTLAND IN THE HIGHLANDS OF CENTRAL NY. REST OF CWA
WILL SEE PC SKIES THIS AFTERNOON WITH SCATTERED FLURRIES AS THE
TEMPERATURES IN THE BNDRY LAYER UNDER THE INVERSION WERE IN THE
MAXIMUM ZONE OF ICE CRYSTAL FORMATION ARND -12C TO 15C (AT 1000 MB
MAX GROWTH IS -12C). HENCE FLOW OVER THE HILLS AND EVEN A LITTLE
CONVECTIVE OVERTURNING IN SC CLDS WILL SPIT OUT SOME FLURRIES.
FARTHER AWAY FROM THE LAKES IN NE PA...WHERE BNDRY LAYER WAS
DRIER...FLURRIES WERE SUBLIMATING SO HAVE NO POPS THERE.
AFTER SUNSET...WITH THE LOSS OF THE SFC HEATING AND THE LL FLOW
TURNING MORE W-SW...SKIES SHUD CLR AND THE LES ACVTY WILL END AS
STATED ABV. I SEE RAPID COOLING IN THE BNDRY LAYER...UNTIL HIGHER
CLDS BEGIN ARRIVING FROM THE SW BTWN 6 AND 9Z AHEAD OF CLIPPER
SYSTEM. I HAVE SOME LIGHT SNOWS AND FLURRIES ARRIVING FROM 9Z TO
12Z ACRS ENTIRE FORECAST AREA FROM APPROACHING CLIPPER SYSTEM. SO
I HAVE ADDED POPS LATE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
XPCT SCT -SHSN TO PREVAIL ON TUE NGT WITH A SFC TROF IN THE
VCNTY...AIDED BY ANOTHER S/WV. IT APPEARS THAT LES SNOWS WILL DVLP
ON WED AS THE SFC TROF DEPARTS AND FLOW BCMS MORE WRLY. ACTIVITY
SHUD BE FAIRLY SHORT LIVED AS WINDS COME ARND TO THE SW WED EVNG
AS LOW PRES MOVS INTO THE CNTRL GTLAKES.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
UPPER LEVEL PATTERN THROUGH MUCH OF THE EXTENDED FEATURES A
NEGATIVE PNA PATTERN, WRN TROF/ERN RIDGE.
MAINLY DRY WEATHER IS EXPECTED WEDNESDAY NIGHT THROUGH THURSDAY
NIGHT AS SFC HIGH PRES WILL BE OFF THE MID ATLANTIC WITH LOW PRES
MOVING INTO THE UPPER GREAT LAKES. SOUTHWEST FLOW WILL PROVIDE
MODERATING CONDITIONS.
LATTER PART OF THE EXTENDED SHOWS THE MEDIUM RANGE MODELS WITH
SIGNIFICANT DIFFERENCES. FOLLOWED WPC GUIDANCE WHICH FOLLOWS THE
ECMWF. ON FRIDAY, SFC LOW PRES MOVING THROUGH EASTERN CANADA WILL
BRING RAIN SHOWERS FOLLOWED BY MIXED RAIN/SNOW SHOWERS AFTER FROPA
FRIDAY NIGHT. THIS BOUNDARY THEN STALLS JUST SOUTH OF AREA WITH
SEVERAL WAVES MOVING NORTHEAST ALONG BOUNDARY. THIS WILL BRING A
CONTINUATION OF CHC POPS FOR RAIN/SNOW SHOWERS.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
A WEAK SFC TROF IS PASSING THROUGH THE REGION THIS AFTERNOON WITH
WIDESPREAD FLURRIES AND OCCASIONAL MVFR CONDITIONS. AT KSYR, A
BETTER DEFINED LAKE SNOW BAND WILL BRING OCCASIONAL IFR CONDITIONS
THROUGH 22Z. BY THIS EVENING WEAK FLOW AND SOME LOW LEVEL DRYING
SHOULD RESULT IN VFR CONDITIONS FOR MUCH OF THE OVERNIGHT PERIOD.
A SYSTEM PASSING TO OUR SOUTH WILL SPREAD IFR/MVFR SNOW ACROSS THE
TERMINALS BEGINNING 10Z-12Z. THE LOWER RESTRICTIONS ARE EXPECTED
OVER THE SRN/CNTRL TERMINALS.
NORTHWEST WINDS AT 1O KNOTS WITH GUST AROUND 18 KNOTS BECOMING LIGHT
THIS EVENING THEN SOUTHEAST AT 5-10 KNOTS ON TUESDAY.
OUTLOOK...
TUESDAY THROUGH WEDNESDAY...RESTRICTIONS POSSIBLE FROM SNOW
SHOWERS.
WEDNESDAY NIGHT THROUGH THURSDAY...BECOMING VFR.
THURSDAY NIGHT THROUGH SATURDAY...RESTRICTIONS POSSIBLE IN RAIN/SNOW
SHOWERS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN
SHORT TERM...
LONG TERM...PVN/RRM
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1252 PM EST MON DEC 16 2013
.SYNOPSIS...
A SERIES OF CLIPPERS WILL BRING PERIODS OF LIGHT SNOW OR SNOW
SHOWERS TO CENTRAL NEW YORK AND NORTHEAST PENNSYLVANIA THROUGH
MIDWEEK. LAKE EFFECT SNOW SHOWERS WILL ALSO BE POSSIBLE AT TIMES
EAST AND SOUTHEAST OF LAKE ONTARIO. TEMPERATURES WILL BEGIN TO
MODERATE BY THE END OF THE WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
KBGM AND KTYX 88D/S CONT TO SHOW A NARROW LES BAND ACRS LAKE
ONTARIO E OF SODUS BAY INTO NW ONONDAGA CO WHERE IT BECOMES MORE
DIFFUSE. VIS SATL IMAGERY ALSO SHOWS THIS BAND WHICH EVENTUALLY
SNAKES DOWN THRU SRN MADISON...OTSEGO TO SCHOHARIE COUNTIES. THE
BAND LOSES ITS ORGANIZATION IN THE MTNS OF CORTLAND SRN MADISON
AND CHENANGO/OTSEGO CO/S. THE FLOW WAS RATHER LIGHT IN THE SFC
LAYER RUNNING LESS THAN 10 KNOTS FROM THE W OR NW. BUT THE 925 MB
FLO REMAINS ARND 10-15 KTS AND CONTS TO DIRECT LAKE MOISTURE IN NC
NY FROM LAKE ONTARIO THRU THE AFTERNOON ON A 290 TO 300 DEGREE
FLOW. TEMPS WERE VERY COLD UNDER THE INVERSION WHICH WERE ARND
-20C NR 7000 FEET AGL. THE INVERSION LOWERS FROM 7000 FEET TO 3000
FEET AGL BY 23Z. THIS OCCURS AS THE COLD BUILDS IN AT LOWER LEVELS
WITH -18C AT 3000 FEET AGL BY 22Z AS PER LATEST RAP MODEL SOUNDING
AT KSYR. THE MEAN WIND BELOW THE INVERSION REMAINS FROM 290-300
DEGREES SO WILL CONT WITH CAT TO LIKELY POPS ACRS ONONDAGA TO
MADISON/SRN ONEIDA CO/S WITH JUST MINOR TWEAKS FROM PREV SHIFT.
HAVE 2-4 INCHES OF SNOW FALLING UP THERE BY LATE EVENING. DECIDED
AGAINST AN LES ADVY BECAUSE THERE WAS SHEAR IN THE LOW-
LEVELS...THE FLO WEAKENS LATER THIS AFTERNOON AND THERE WAS LARGE
SCALE SUBSC PUSHING THE INVERSION DOWN.
REST OF CWA WILL SEE SCT-BKN SC WITH FLURRIES AS THE MAX GROWTH
ZONE FOR ICE CRYSTALS IS NOT FAR ABV THE SFC. THIS MEANS THAT ANY
LIFTG EITHER OROGRAPHIC OR SIMPLY SOME WEAK CONVECTIVE OVERTURNING
IN AN SC CLOUD CUD PRODUCE A FEW FLAKES FOR THE REMAINDER OF THE
AFTERNOON.
SUBSC CONTS TO WORK IN ACRS THE CWA TONIGHT. THE LES WILL
EVENTUALLY WEAKEN AND SHIFT N OF THE CWA AS THE FLOW TURNS MORE
SWRLY BY 3Z OR SO. CLDS FROM NEXT SYSTEM WILL ADVECT OVHD LATER IN
THE NIGHT. HENCE I SEE MAINLY CLR SKIES MUCH OF CWA LEADING TO
SIGNIFICANT NET RAD COOLING IN THE EVENING...THINK TEMPS WILL FALL
QUICKLY...THEN REBOUND SOME LATE TONIGHT AS THE CLDS INCREASE AND
THICKEN. LATEST LAV GUIDC SUGGESTS THIS.
PREVIOUS DISCUSSION IS BELOW...
445 AM UPDATE...LES ADVISORY FOR NRN ONEIDA CANCELLED. PREV BLO...
ARCTIC FNT ENTERING THE NRN CWA EARLY THIS MRNG SHIFTING THE LOW
LVL FLOW TO MORE OF A NWLY DIRECTION. LES SNOW WILL LIKELY REMAIN
OVER ONON/MADISON AND FAR SRN ONEIDA TDA. VERY DRY LOW LVL AIR
WORKING INTO THE RGN BEHIND THIS FNT...AND LOW LVL FLOW WEAKENS
LATER THIS MRNG. XPCT ACCUMS GNRLY IN THE 2-3 INCH RNG FOR MUCH OF
THIS AREA TDA. THIS ACTIVITY WILL GRADUALLY SHIFT NWD LATE TDA
INTO THE EVNG HRS AS LOW LVL FLOW BACKS. SCT -SHSN ACRS PORTIONS
OF THE SRN TIER INTO NE PA THIS MRNG DUE TO ERIE STREAMER.
LATE TNGT NXT S/WV...CRNTLY OVER SRN CANADA...WILL DIVE SEWD INTO
THE FCST AREA. AREA OF LGT SNOW WILL BEGIN TO WORK INTO THE RGN
AFTER 06Z. MIN TEMPS TNGT LIKELY TO BE ARND 06Z WITH STEADY OR
SLOWLY RISING TEMPS AFTERWARDS. THIS AREA OF SNOW SHUD PUSH EWD
AND OUT OF THE RGN BY LATE MRNG OR EARLY AFTN...BUT NXT S/WV IS RIGHT
ON IT`S HEELS WHICH MAY SPREAD MORE LGT SNOW ACRS THE RGN LATER
IN THE AFTN. ATTM...WE ARE ANTICIPATING ACCUMS IN THE 2-4 INCH RNG
WITH THIS SYSTEM. WILL HAVE TO MONITOR 2NDRY CYCLOGENESIS OFF THE
JERSEY CST WHICH COULD BUMP UP AMTS A BIT ACRS THE CATSKILLS AND
POCONOS.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
XPCT SCT -SHSN TO PREVAIL ON TUE NGT WITH A SFC TROF IN THE
VCNTY...AIDED BY ANOTHER S/WV. IT APPEARS THAT LES SNOWS WILL DVLP
ON WED AS THE SFC TROF DEPARTS AND FLOW BCMS MORE WRLY. ACTIVITY
SHUD BE FAIRLY SHORT LIVED AS WINDS COME ARND TO THE SW WED EVNG
AS LOW PRES MOVS INTO THE CNTRL GTLAKES.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
UPPER LEVEL PATTERN THROUGH MUCH OF THE EXTENDED FEATURES A
NEGATIVE PNA PATTERN, WRN TROF/ERN RIDGE.
MAINLY DRY WEATHER IS EXPECTED WEDNESDAY NIGHT THROUGH THURSDAY
NIGHT AS SFC HIGH PRES WILL BE OFF THE MID ATLANTIC WITH LOW PRES
MOVING INTO THE UPPER GREAT LAKES. SOUTHWEST FLOW WILL PROVIDE
MODERATING CONDITIONS.
LATTER PART OF THE EXTENDED SHOWS THE MEDIUM RANGE MODELS WITH
SIGNIFICANT DIFFERENCES. FOLLOWED WPC GUIDANCE WHICH FOLLOWS THE
ECMWF. ON FRIDAY, SFC LOW PRES MOVING THROUGH EASTERN CANADA WILL
BRING RAIN SHOWERS FOLLOWED BY MIXED RAIN/SNOW SHOWERS AFTER FROPA
FRIDAY NIGHT. THIS BOUNDARY THEN STALLS JUST SOUTH OF AREA WITH
SEVERAL WAVES MOVING NORTHEAST ALONG BOUNDARY. THIS WILL BRING A
CONTINUATION OF CHC POPS FOR RAIN/SNOW SHOWERS.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
A WEAK SFC TROF IS PASSING THROUGH THE REGION THIS AFTERNOON WITH
WIDESPREAD FLURRIES AND OCCASIONAL MVFR CONDITIONS. AT KSYR, A
BETTER DEFINED LAKE SNOW BAND WILL BRING OCCASIONAL IFR CONDITIONS
THROUGH 22Z. BY THIS EVENING WEAK FLOW AND SOME LOW LEVEL DRYING
SHOULD RESULT IN VFR CONDITIONS FOR MUCH OF THE OVERNIGHT PERIOD.
A SYSTEM PASSING TO OUR SOUTH WILL SPREAD IFR/MVFR SNOW ACROSS THE
TERMINALS BEGINNING 10Z-12Z. THE LOWER RESTRICTIONS ARE EXPECTED
OVER THE SRN/CNTRL TERMINALS.
NORTHWEST WINDS AT 1O KNOTS WITH GUST AROUND 18 KNOTS BECOMING LIGHT
THIS EVENING THEN SOUTHEAST AT 5-10 KNOTS ON TUESDAY.
OUTLOOK...
TUESDAY THROUGH WEDNESDAY...RESTRICTIONS POSSIBLE FROM SNOW
SHOWERS.
WEDNESDAY NIGHT THROUGH THURSDAY...BECOMING VFR.
THURSDAY NIGHT THROUGH SATURDAY...RESTRICTIONS POSSIBLE IN RAIN/SNOW
SHOWERS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN
SHORT TERM...
LONG TERM...PVN/RRM
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
334 PM CST MON DEC 16 2013
.SHORT TERM...(THIS AFTERNOON THROUGH TUESDAY AFTERNOON)
ISSUED AT 334 PM CST MON DEC 16 2013
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE AREAS OF
BLOWING/DRIFTING SNOW RESULTING IN POSSIBLE ICY ROADS/BLACK ICE
ACROSS THE NORTH THROUGH THIS EVENING...AND A CHANCE OF LIGHT SNOW
THIS AFTERNOON AND EVENING WEST TO EAST.
CURRENTLY...STRONG NORTHWEST FLOW ALOFT WITH A SHARP RIDGE OFF
THE WEST COAST AND A BROAD LONG WAVE TROUGH OVER THE EASTERN
UNITED STATES. UPPER LEVEL JET STREAM EXTENDS FROM THE TOP OF THE
RIDGE OVER ALASKA...SOUTHEAST INTO THE NORTHERN HIGH PLAINS OF
MT/WY. STRONG PRESSURE GRADIENT CONTINUES TO DEVELOP ACROSS WEST
AND CENTRAL NORTH DAKOTA WEST OF A SURFACE TROUGH OVER FAR WESTERN
MINNESOTA. GRADIENT FORCING WILL INCREASE THROUGHOUT THE DAY AND
INTO THIS EVENING AS THE TROUGH REMAINS QUASI-STATIONARY AND AS A
SURFACE HIGH BUILDS OFF TO OUR WEST CENTERED OVER THE NORTHEASTERN
SNAKE RIVER VALLEY OF EASTERN IDAHO.
MODELS EARLIER WERE LOOKING LIKE THEY WERE TRENDING TOWARDS A
CONSENSUS REGARDING PRECIPITATION CHANCES THIS AFTERNOON AND
EVENING. NOW NOT SO MUCH. MOISTURE IS HAVING A HARD TIME REACHING
THE GROUND ACROSS MY WEST CENTRAL. WEB CAMS OVER SOUTHWEST NORTH
DAKOTA DEFINITELY SHOWING SNOWFALL ALTHOUGH MOSTLY MELTING ON THE
ROAD SURFACES. BOWMAN RADAR STILL LIT UP...AND BAKER MT STILL
REPORTING SNOW. THE 12Z ECMWF AND LATEST RAP SEEM TO BE CAPTURING
REALITY THE BEST VERSUS OTHER GUIDANCE. LEANED IN THEIR DIRECTION
WITH LINGERING LIGHT PRECIPITATION SOUTHWEST NOW THROUGH THIS
EVENING...AND ANOTHER AREA OF LIGHT PRECIPITATION MOVING SOUTHEAST
OVER MY EASTERN COUNTIES LATE AFTERNOON AND EVENING. THIS AREA
CURRENTLY SHOWING UP ON RADAR OVER SOUTHEAST SK/SOUTHWEST
MANITOBA.
THE INCREASING PRESSURE GRADIENT WILL SEE WINDS INCREASE TO JUST
BELOW WIND ADVISORY CRITERIA MOST LOCATIONS NOW THROUGH THE
EVENING HOURS...BEFORE WINDING DOWN AFTER 06Z. AT THIS TIME WINDS
ARE SUSTAINED AT 15-25 MPH MOST LOCATIONS...WITH GUSTS AS HIGH AS
35 MPH REPORTED. ROAD SFC TEMPS REMAIN AT OR BELOW FREEZING NORTH
AND ABOVE 32F SOUTH. AIR TEMPERATURES MAINLY IN THE LOWER TO MID
30S. WIND DRIVEN SNOW IS STILL EXPECTED TO CREATE HAZARDOUS
TRAVEL...ESPECIALLY WHEN WET ROADS REFREEZE AND/OR BLOWING SNOW
STARTS TO STICK THIS AFTERNOON. WILL MAINTAIN THE SPECIAL WEATHER
STATEMENT AS IS FOR NOW AND LET THE EVENING CREW DECIDE ITS FATE
AT THE 7PM UPDATE PERIOD.
TUESDAY MORNING/AFTERNOON LOOK TO BE RELATIVELY QUIET WITH PARTLY
CLOUDY SKIES AND DRY CONDITIONS. A WARM FRONT MOVING INTO
SOUTHEAST MONTANA WILL SEE TEMPERATURES WARMING TO NEAR 40 OVER MY
FAR SOUTHWEST CORNER. SHARP TEMPERATURE GRADIENT WITH HIGHS AROUND
15 ABOVE FOR THE TURTLE MOUNTAINS.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 334 PM CST MON DEC 16 2013
THE MAIN FORECAST ISSUE IS SNOWFALL AMOUNTS AND COVERAGE WITH THE
MID WEEK STORM.
A LOW PRESSURE CLIPPER SYSTEM IS FORECAST TO DEVELOP TUESDAY OVER
ALBERTA AND MOVE EAST/SOUTHEAST TOWARDS NORTH DAKOTA TUESDAY NIGHT.
WINDS ACROSS THE FORECAST AREA SHOULD START OUT SOUTHERLY EARLY
TUESDAY EVENING...BECOMING WEST DURING THE EVENING/NIGHT WITH WARM
ADVECTION AS NORTH DAKOTA REMAINS IN THE WARM SECTOR OF THE SYSTEM.
ON WEDNESDAY THE CLIPPER LOW DEVELOPS INTO MORE OF A COLD FRONT IN
NATURE...MOVING SOUTH ACROSS THE STATE. IT APPEARS THAT THE MARKED
COLD ADVECTION WITH THE ARCTIC AIR BEGINS WEDNESDAY AROUND NOON IN
THE NORTH AND DURING THE AFTERNOON FARTHER SOUTH. HIGHS WEDNESDAY
SHOULD RANGE FROM THE UPPER TEENS/MID 20S NORTH TO THE UPPER 20S/30S
SOUTH. KEPT A SLIGHT CHANCE OF LIGHT SNOW IN THE NORTHWEST AND NORTH
CENTRAL NORTH DAKOTA ALONG THE ARCTIC COLD FRONT.
MODEL AGREEMENT CONTINUES TO IMPROVE REGARDING THE MAIN SYNOPTIC
FEATURES OF THE UPPER LEVEL TROUGH AND VORT ENERGY IMPULSES...AS
WELL AS THE POSITION OF THE COLD FRONT AND ARCTIC HIGH PRESSURE
SYSTEM. THE UPPER LEVEL TROUGH MOVES ACROSS NORTH DAKOTA
THURSDAY/THURSDAY EVENING. MEANWHILE THE SURFACE ARCTIC HIGH DIVES
SOUTH FROM ALBERTA INTO MONTANA WEDNESDAY NIGHT/THURSDAY. IN NORTH
DAKOTA...THE ARCTIC COLD FRONT MOVES SOUTH ACROSS THE STATE
WEDNESDAY AFTERNOON/EVENING WITH COLD ADVECTION CONTINUING THROUGH
THE DAY THURSDAY.
THE PLACEMENT OF SNOWFALL LOOKS TO BE HIGHEST IN MONTANA...BUT SNOW
ACCUMULATIONS ALONG THE NORTH DAKOTA/SOUTH DAKOTA BORDER SHOULD BE
IN THE 2-4 INCH RANGE. FOR WESTERN AND CENTRAL NORTH DAKOTA THE BULK
OF THE SNOWFALL SHOULD BEGIN WEDNESDAY NIGHT IN THE WEST...AND
EXPAND INTO CENTRAL NORTH DAKOTA AFTER MIDNIGHT WEDNESDAY
NIGHT/DAYBREAK THURSDAY MORNING...CONTINUE FOR MUCH OF THE
DAY THURSDAY...BEFORE TAPERING OFF IN THE JAMES RIVER VALLEY
THURSDAY EVENING.
VERY COLD AIR WILL ACCOMPANY THIS STORM SYSTEM WEDNESDAY NIGHT
THROUGH SATURDAY. SOME AREAS...ESPECIALLY THE NORTH...MAY HIT WIND
CHILL ADVISORY CRITERIA WEDNESDAY NIGHT AND THURSDAY NIGHT.
THE UPPER LEVEL PATTERN THROUGH THE WEEKEND CONTINUES NORTHWEST FLOW
ALOFT WITH A LARGE HUDSON BAY LOW IN PLACE. TOWARDS THE BEGINNING OF
NEXT WEEK THE MODELS ARE HINTING AT A MORE PROGRESSIVE PATTERN WITH
A WESTERN RIDGE BUILDING AND PUSHING THE HUDSON BAY LOW EASTWARD. NO
BIG WARM-UPS BUT NO BIG ARCTIC OUTBREAKS EITHER.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 334 PM CST MON DEC 16 2013
MAINLY VFR CIGS/VSBYS EXPECTED NEXT 24HR. BKN/OVC CIGS BETWEEN
5KFT AND 10KFT WITH GUSTY WEST-NORTHWESTERLY WINDS OF 20KT TO 30KT
WILL DOMINATE MOST OF THE AERODROMES TODAY AND THIS EVENING.
BLOWING/DRIFTING SNOW IS POSSIBLE BUT NOT EXPECTED TO AFFECT
VISIBILITIES BELOW VFR AT THIS TIME. A VCSH AND A TEMPO GROUP WILL
BE MAINTAINED FOR KDIK AND KJMS. SHOULD REMAIN MAINLY DRY OTHER
TERMINALS. EXPECT SCT CLOUDS TO SKC AFTER 06Z TUESDAY WITH BRISK
WINDS OF 15KT CONTINUING THROUGH 12Z TUESDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...NH
LONG TERM...JV
AVIATION...NH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
100 PM CST MON DEC 16 2013
.UPDATE...
ISSUED AT 100 PM CST MON DEC 16 2013
STRONG NORTHWEST FLOW ALOFT WITH A RIDGE OFF THE WEST COAST AND A
BROAD TROUGH OVER THE EASTERN CONUS. UPPER LEVEL JET STREAM
EXTENDS FROM ALASKA SOUTHEAST INTO THE NORTHERN HIGH PLAINS.
STRONG PRESSURE GRADIENT TAKING SHAPE ACROSS WEST AND CENTRAL
NORTH DAKOTA WEST OF A SURFACE TROUGH NEAR THE RED RIVER VALLEY.
GRADIENT FORCING WILL INCREASE THROUGHOUT THE DAY AND INTO THIS
EVENING AS THE TROUGH REMAINS QUASI-STATIONARY AND AS A SURFACE
HIGH BUILDS OFF TO OUR WEST CENTERED OVER THE NORTHEASTERN SNAKE
RIVER VALLEY OF EASTERN IDAHO.
MODELS ARE STARTING TO SHOW THEIR CARDS REGARDING PRECIPITATION
CHANCES THIS AFTERNOON AND EVENING. DECENT AREA OF RADAR ECHOS
COVER MOST OF NORTHEASTERN MONTANA. LATEST NAM AND 4KM WRF ARE
DEPICTING THIS RATHER WELL. LEANED ON THEIR GUIDANCE IN BRINGING
THIS AREA OF PRECIPITATION EAST ACROSS WEST AND CENTRAL NORTH
DAKOTA THROUGH THIS AFTERNOON AND EARLY EVENING AS UPPER LEVEL
DIVERGENCE IN THE LEFT EXIT REGION OF THE UPPER JET OVERSPREADS
THE NORTHERN PLAINS. EMBEDDED MID LEVEL IMPULSE WILL ALSO AID IN
PRECIPITATION DEVELOPMENT. AT THIS TIME EXPECT QPF TO BE LIGHT
WITH MAYBE UP TO HALF AN INCH OF SNOWFALL POSSIBLE.
WITH THE INCREASING PRESSURE GRADIENT MENTIONED ABOVE...WILL SEE
WINDS INCREASE TO JUST BELOW WIND ADVISORY CRITERIA THIS AFTERNOON
MOST LOCATIONS...THEN MORE CENTRAL AND EAST THIS EVENING BEFORE
WINDING DOWN AFTER 06Z. AT THIS TIME WINDS ARE SUSTAINED AT 15-20
MPH MOST LOCATIONS...WITH GUSTS AS HIGH AS 30 MPH REPORTED...AND
WILL ONLY INCREASE OVER THE NEXT FEW HOURS. NORTH DAKOTA DOT
REPORTED FROST COVERED ROADS ACROSS CERTAIN PARTS OF THE
STATE THE PAST SEVERAL HOURS...IN ADDITION TO NOW ICE COVERED
ROADS NORTH WHERE ROAD SFC TEMPS REMAIN BELOW FREEZING BUT AIR
TEMPERATURES HAVE WARMED TO NEAR 32F. WIND DRIVEN SNOW THUS
CREATING HAZARDOUS TRAVEL. EXPECT TRAVEL PROBLEMS TO ONLY INCREASE
FOR THE REMAINDER OF THE AFTERNOON AND EVENING. WILL MAINTAIN THE
SPECIAL WEATHER STATEMENT AS IS FOR NOW. MAY NEED TO CONSIDER
EXPANDING DEPENDING ON HOW WARM WE WILL GET...ANY REPORTS FROM THE
DOT OR LAW ENFORCEMENT...AND HOW MUCH SNOW MAY FALL THROUGH EARLY
TO MID EVENING.
UPDATE
ISSUED AT 1007 AM CST MON DEC 16 2013
HOURLY WEATHER ELEMENTS WERE UPDATED BASED ON LATEST OBSERVATIONS.
DID NOT CHANGE OUR FORECAST HIGHS MUCH FROM WHAT WAS INHERITED.
MAIN UPDATE WAS TO INCREASE POPS SOUTHWEST THIS MORNING WITH BAKER
MT REPORTING LIGHT SNOW AND THE BOWMAN RADAR LIT UP PRETTY GOOD
OVER MY FAR SOUTHWEST CORNER.
UPDATE ISSUED AT 642 AM CST MON DEC 16 2013
UPDATE FOR EARLY MORNING TEMPERATURE TRENDS AND TO INCREASE POPS
NORTH AND EAST THIS AFTERNOON. LATEST TRENDS AND HI-RES MODEL RUNS
INDICATE LITTLE OR NO THREAT FOR FREEZING RAIN/SLEET WITH P-TYPE
EXPECTED TO BE ALL SNOW OR POSSIBLE RAIN/SNOW MIX THIS AFTERNOON
IN LOCATIONS WITH WARMER SURFACE TEMPS. LATEST EARLY MORNING MODEL
RUNS INCLUDING THE 06Z WRF AND 11Z RAP ARE ALSO INSISTENT ON AN
AREA OF LIGHT SNOW TRACKING OVER THE NORTHERN AND EASTERN PORTIONS
OF THE FORECAST AREA THIS AFTERNOON. HAVE INCREASED POPS DURING
THE AFTERNOON. THE LIGHT SNOW MAY ADD TO THE TRAVEL HAZARDS...IN
THE FORM OF BRIEF REDUCED VISIBILITY...AS WINDS GUST TO 35 MPH.
THIS IS IN ADDITION TO THE THREAT OF EXISTING SNOW BLOWING ACROSS
ROADS...MELTING...THEN RE-FREEZING.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CST MON DEC 16 2013
MAIN HIGHLIGHTS WILL BE AREAS OF BLOWING/DRIFTING SNOW WITH ICY
ROADS/BLACK ICE POSSIBLY DEVELOPING MONDAY AFTERNOON NORTH...AND A
SLIGHT CHANCE OF MIXED PRECIPITATION THIS AFTERNOON AS ANOTHER
SHORTWAVE TRAVERSES THROUGH.
THE LATEST WATER VAPOR IMAGERY SHOWS TWO SHORTWAVES OF INTEREST.
THE FIRST WAS LOCATED NEAR LAKE WINNIPEG MOVING SOUTHEAST WITH
TIME. LOCAL AND REGIONAL RADAR WAS SHOWING AN AREA OF LIGHT SNOW
FROM NORTHEAST MONTANA...ACROSS NORTHWEST AND INTO NORTH CENTRAL
NORTH DAKOTA. THIS SHORTWAVE IS ALSO INTERACTING WITH A SURFACE
WARM FRONT LOCATED FROM NEAR SHERWOOD...TO MINOT...AND SOUTH TO
GLEN ULLIN AND THEN SNAKING INTO PIERRE SOUTH DAKOTA. MINOT DUAL
POL RADAR SHOWS SOME POTENTIAL FOR AN ELEVATED MELTING LAYER AND
POSSIBLY MIXED PRECIPITATION. THE RAP13 WAS INDICATING THAT LIGHT
SNOW WOULD MAINLY DOMINATE THE PRECIPITATION BAND WITH THE
POSSIBILITY OF LIGHT FREEZING RAIN ON THE BACK EDGE. WILL CONTINUE
WITH THIS THINKING EARLY THIS MORNING.
THE SECOND SHORTWAVE WAS LOCATED IN EAST CENTRAL ALBERTA...WHICH
IS FORECAST TO SHIFT INTO MOHALL BY 00Z TUESDAY. THE LEFT EXIT
REGION OF A 140KT H3 JET WILL CREATE ENOUGH LIFT TO PRODUCE A
SLIGHT CHC OF MIXED PRECIPITATION FOR THE NORTH THIS AFTERNOON.
MOST TEMPERATURES WILL WARM ABOVE FREEZING FROM WEST TO EAST
TODAY AS THE WARM FRONT CONTINUES TO ADVANCE EAST. THE MAIN ISSUE
THIS AFTERNOON WILL BE BRISK WESTERLY WINDS OF 20 TO 30 MPH
CREATING BLOWING/DRIFTING SNOW ACROSS THE HIGHWAYS WITH POSSIBLE
BLACK ICE FORMING. A SPECIAL WEATHER STATEMENT WAS ISSUED
HIGHLIGHTING THE POTENTIAL FOR BLOWING AND DRIFTING
SNOW...MELTING...AND THEN REFREEZING ACROSS THE NORTH. GIVEN
SUCCESSIVE ROUNDS OF LIGHT SNOW THE LAST FEW DAYS...BRISK
WINDS...AND AFTERNOON TEMPERATURES HOVERING AROUND FREEZING...THIS
AREA WILL BE IN LINE FOR THE BLOWING/DRIFTING/MELTING/REFREEZING
PROCESSES. FARTHER SOUTH AND WEST WHERE TEMPERATURES WILL BE IN
THE UPPER 30S...EXPECT ICY TRAVEL TO DEVELOP TONIGHT ONCE WE FALL
BELOW FREEZING AFTER SUNSET. AFTERNOON HIGHS TODAY WILL RANGE FROM
THE UPPER 20S IN THE TURTLE MOUNTAINS TO THE UPPER 30S WEST.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 315 AM CST MON DEC 16 2013
THE MAIN FORECAST ISSUE IS SNOWFALL AMOUNTS AND COVERAGE WITH THE
MID WEEK STORM.
ON TUESDAY...COLDER AIR WILL BEGIN TO GRADUALLY SAG INTO NORTHEAST
NORTH DAKOTA WITH HIGHS EXPECTED TO ONLY REACH THE TEENS. MILD
WEATHER WILL CONTINUE IN THE SOUTHWEST WITH HIGHS IN THE 30S LIKELY.
MODEL AGREEMENT IS IMPROVING REGARDING THE NORTHERN STREAM TROUGH
THAT WILL IMPACT THE STATE WEDNESDAY NIGHT INTO THURSDAY. THE
SOUTHERN HALF OF THE FORECAST AREA...PARTICULARLY ALONG AND SOUTH OF
THE INTERSTATE 94 CORRIDOR...IS STILL FAVORED FOR THE HIGHER
SNOWFALL AMOUNTS. MODEL QPF GENERALLY RANGES FROM 0.2 TO AROUND 0.3
INCHES. WITH RELATIVELY CONSERVATIVE SNOW TO LIQUID RATIOS NEAR OR
BELOW 20 TO 1...THAT WOULD RESULT IN GENERAL 4 TO 6 INCH SNOWFALL
AMOUNTS. HOWEVER...WITH THE INCREASINGLY COLD THERMAL PROFILE AND
POTENTIAL FOR NARROW BANDS OF ENHANCED LIFT...WE COULD EASILY SEE
PERIODS OF HIGHER RATIOS...WHICH WOULD PUSH SNOWFALL AMOUNTS OVER
WARNING CRITERIA SOME AREAS. PLENTY COULD CHANGE OVER THE NEXT 2 TO
3 DAYS...BUT THE POTENTIAL IS THERE.
VERY COLD AIR WILL ACCOMPANY THE TROUGH WEDNESDAY NIGHT THROUGH
SATURDAY. SOME AREAS...ESPECIALLY THE NORTH...MAY HIT WIND CHILL
ADVISORY CRITERIA WEDNESDAY AND THURSDAY NIGHTS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 100 PM CST MON DEC 16 2013
MAINLY VFR CIGS/VSBYS EXPECTED NEXT 24HR. BKN/OVC CIGS BETWEEN
5KFT AND 10KFT WITH GUSTY WEST-NORTHWESTERLY WINDS OF 20KT TO 30KT
WILL DOMINATE MOST OF THE AERODROMES TODAY. BLOWING/DRIFTING SNOW
IS POSSIBLE BUT NOT EXPECTED TO AFFECT VISIBILITIES BELOW VFR AT
THIS TIME. A VCSH AND A TEMPO GROUP HAS BEEN ADDED ALL LOCATIONS
THIS AFTERNOON THROUGH MID EVENING AS AN AREA OF SNOW IS EXPECTED
TO MOVE EAST ACROSS NORTH DAKOTA OVER THE NEXT SEVERAL
HOURS...POSSIBLY ACCOMPANIED BY A BRIEF MVFR CIG AND/OR VIS.
EXPECT SCT CLOUDS TO SKC AFTER 06Z TUESDAY WITH BRISK WINDS OF
15KT CONTINUING THROUGH 12Z TUESDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
SHORT TERM...KS
LONG TERM...RK
AVIATION...NH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1007 AM CST MON DEC 16 2013
.UPDATE...
ISSUED AT 1007 AM CST MON DEC 16 2013
HOURLY WEATHER ELEMENTS WERE UPDATED BASED ON LATEST OBSERVATIONS.
DID NOT CHANGE OUR FORECAST HIGHS MUCH FROM WHAT WAS INHERITED.
MAIN UPDATE WAS TO INCREASE POPS SOUTHWEST THIS MORNING WITH BAKER
MT REPORTING LIGHT SNOW AND THE BOWMAN RADAR LIT UP PRETTY GOOD
OVER MY FAR SOUTHWEST CORNER.
UPDATE ISSUED AT 642 AM CST MON DEC 16 2013
UPDATE FOR EARLY MORNING TEMPERATURE TRENDS AND TO INCREASE POPS
NORTH AND EAST THIS AFTERNOON. LATEST TRENDS AND HI-RES MODEL RUNS
INDICATE LITTLE OR NO THREAT FOR FREEZING RAIN/SLEET WITH P-TYPE
EXPECTED TO BE ALL SNOW OR POSSIBLE RAIN/SNOW MIX THIS AFTERNOON
IN LOCATIONS WITH WARMER SURFACE TEMPS. LATEST EARLY MORNING MODEL
RUNS INCLUDING THE 06Z WRF AND 11Z RAP ARE ALSO INSISTENT ON AN
AREA OF LIGHT SNOW TRACKING OVER THE NORTHERN AND EASTERN PORTIONS
OF THE FORECAST AREA THIS AFTERNOON. HAVE INCREASED POPS DURING
THE AFTERNOON. THE LIGHT SNOW MAY ADD TO THE TRAVEL HAZARDS...IN
THE FORM OF BRIEF REDUCED VISIBILITY...AS WINDS GUST TO 35 MPH.
THIS IS IN ADDITION TO THE THREAT OF EXISTING SNOW BLOWING ACROSS
ROADS...MELTING...THEN RE-FREEZING.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CST MON DEC 16 2013
MAIN HIGHLIGHTS WILL BE AREAS OF BLOWING/DRIFTING SNOW WITH ICY
ROADS/BLACK ICE POSSIBLY DEVELOPING MONDAY AFTERNOON NORTH...AND A
SLIGHT CHANCE OF MIXED PRECIPITATION THIS AFTERNOON AS ANOTHER
SHORTWAVE TRAVERSES THROUGH.
THE LATEST WATER VAPOR IMAGERY SHOWS TWO SHORTWAVES OF INTEREST.
THE FIRST WAS LOCATED NEAR LAKE WINNIPEG MOVING SOUTHEAST WITH
TIME. LOCAL AND REGIONAL RADAR WAS SHOWING AN AREA OF LIGHT SNOW
FROM NORTHEAST MONTANA...ACROSS NORTHWEST AND INTO NORTH CENTRAL
NORTH DAKOTA. THIS SHORTWAVE IS ALSO INTERACTING WITH A SURFACE
WARM FRONT LOCATED FROM NEAR SHERWOOD...TO MINOT...AND SOUTH TO
GLEN ULLIN AND THEN SNAKING INTO PIERRE SOUTH DAKOTA. MINOT DUAL
POL RADAR SHOWS SOME POTENTIAL FOR AN ELEVATED MELTING LAYER AND
POSSIBLY MIXED PRECIPITATION. THE RAP13 WAS INDICATING THAT LIGHT
SNOW WOULD MAINLY DOMINATE THE PRECIPITATION BAND WITH THE
POSSIBILITY OF LIGHT FREEZING RAIN ON THE BACK EDGE. WILL CONTINUE
WITH THIS THINKING EARLY THIS MORNING.
THE SECOND SHORTWAVE WAS LOCATED IN EAST CENTRAL ALBERTA...WHICH
IS FORECAST TO SHIFT INTO MOHALL BY 00Z TUESDAY. THE LEFT EXIT
REGION OF A 140KT H3 JET WILL CREATE ENOUGH LIFT TO PRODUCE A
SLIGHT CHC OF MIXED PRECIPITATION FOR THE NORTH THIS AFTERNOON.
MOST TEMPERATURES WILL WARM ABOVE FREEZING FROM WEST TO EAST
TODAY AS THE WARM FRONT CONTINUES TO ADVANCE EAST. THE MAIN ISSUE
THIS AFTERNOON WILL BE BRISK WESTERLY WINDS OF 20 TO 30 MPH
CREATING BLOWING/DRIFTING SNOW ACROSS THE HIGHWAYS WITH POSSIBLE
BLACK ICE FORMING. A SPECIAL WEATHER STATEMENT WAS ISSUED
HIGHLIGHTING THE POTENTIAL FOR BLOWING AND DRIFTING
SNOW...MELTING...AND THEN REFREEZING ACROSS THE NORTH. GIVEN
SUCCESSIVE ROUNDS OF LIGHT SNOW THE LAST FEW DAYS...BRISK
WINDS...AND AFTERNOON TEMPERATURES HOVERING AROUND FREEZING...THIS
AREA WILL BE IN LINE FOR THE BLOWING/DRIFTING/MELTING/REFREEZING
PROCESSES. FARTHER SOUTH AND WEST WHERE TEMPERATURES WILL BE IN
THE UPPER 30S...EXPECT ICY TRAVEL TO DEVELOP TONIGHT ONCE WE FALL
BELOW FREEZING AFTER SUNSET. AFTERNOON HIGHS TODAY WILL RANGE FROM
THE UPPER 20S IN THE TURTLE MOUNTAINS TO THE UPPER 30S WEST.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 315 AM CST MON DEC 16 2013
THE MAIN FORECAST ISSUE IS SNOWFALL AMOUNTS AND COVERAGE WITH THE
MID WEEK STORM.
ON TUESDAY...COLDER AIR WILL BEGIN TO GRADUALLY SAG INTO NORTHEAST
NORTH DAKOTA WITH HIGHS EXPECTED TO ONLY REACH THE TEENS. MILD
WEATHER WILL CONTINUE IN THE SOUTHWEST WITH HIGHS IN THE 30S LIKELY.
MODEL AGREEMENT IS IMPROVING REGARDING THE NORTHERN STREAM TROUGH
THAT WILL IMPACT THE STATE WEDNESDAY NIGHT INTO THURSDAY. THE
SOUTHERN HALF OF THE FORECAST AREA...PARTICULARLY ALONG AND SOUTH OF
THE INTERSTATE 94 CORRIDOR...IS STILL FAVORED FOR THE HIGHER
SNOWFALL AMOUNTS. MODEL QPF GENERALLY RANGES FROM 0.2 TO AROUND 0.3
INCHES. WITH RELATIVELY CONSERVATIVE SNOW TO LIQUID RATIOS NEAR OR
BELOW 20 TO 1...THAT WOULD RESULT IN GENERAL 4 TO 6 INCH SNOWFALL
AMOUNTS. HOWEVER...WITH THE INCREASINGLY COLD THERMAL PROFILE AND
POTENTIAL FOR NARROW BANDS OF ENHANCED LIFT...WE COULD EASILY SEE
PERIODS OF HIGHER RATIOS...WHICH WOULD PUSH SNOWFALL AMOUNTS OVER
WARNING CRITERIA SOME AREAS. PLENTY COULD CHANGE OVER THE NEXT 2 TO
3 DAYS...BUT THE POTENTIAL IS THERE.
VERY COLD AIR WILL ACCOMPANY THE TROUGH WEDNESDAY NIGHT THROUGH
SATURDAY. SOME AREAS...ESPECIALLY THE NORTH...MAY HIT WIND CHILL
ADVISORY CRITERIA WEDNESDAY AND THURSDAY NIGHTS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 642 AM CST MON DEC 16 2013
VFR CIGS/VSBYS CAN BE EXPECTED NEXT 24HR. BKN/OVC CIGS BETWEEN 5KFT
AND 10KFT WITH GUSTY WEST-NORTHWESTERLY WINDS OF 20KT TO 30KT WILL
DOMINATE MOST OF THE AERODROMES. BLOWING/DRIFTING SNOW IS POSSIBLE
BUT NOT EXPECTED TO AFFECT VISIBILITIES BELOW VFR AT THIS TIME. A
VCSH HAS BEEN ADDED TO KISN/KMOT/KJMS MONDAY AFTERNOON AS AN UPPER
LEVEL DISTURBANCE TRACKS ACROSS NORTHERN AND CENTRAL NORTH DAKOTA.
EXPECT SCT CLOUDS TO SKC AFTER 00Z TUESDAY WITH BRISK WINDS OF 15KT
CONTINUING THROUGH 12Z TUESDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
SHORT TERM...KS
LONG TERM...RK
AVIATION...KS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1159 AM CST MON DEC 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 329 AM CST MON DEC 16 2013
MONITORING DYNAMIC SYSTEM NEAR LAKE WINNIPEG AND THE RADAR BAND
DEVELOPING ACROSS ND AT 08Z. OTHER RADAR ECHO AND SOME SCT REPORTS
OF SN- BEING REPORTED ALONG WARM ADVECTION ARM EXTENDING THROUGH
THE EASTERN DAKOTAS AND INTO THE MN RIVER VALLEY. THIS SYSTEM WAS
HANDLED WELL AND FEW CHANGES WERE MADE TO THE ONGOING FORECAST
FOR TODAY EXCEPT FOR TIMING.
STRONG CIRCULATION CLEARLY SEEN IN GOES WATER VAPOR IMAGERY NEAR
LAKE WINNIPEG AND THIS SYSTEM AND ITS POTENTIAL VORTICITY
ADVECTION WILL DIG TOWARD LAKE SUPERIOR AND DRAG GOOD DYNAMICS
ACROSS NORTHERN WI TODAY. THIS POTENTIAL VORTICITY ADVECTION...IN
COMBINATION WITH WARM ADVECTION ALONG THE THERMAL RIBBON FROM
700-900 MB...AND SOME MODERATE 250MB JET EXIT REGION DIVERGENCE WILL
PRODUCE A SWATH OF 1-2 SNOW TODAY. HRRR TRENDS SHOW A SOMEWHAT
NARROW BAND SHIFTING ACROSS WI DURING THE DAY...WITH ABOUT 2
HOURS OF SNOW AT ANY ONE POINT. HI-RES WINDOWS FROM NCEP NMM/ARW
16.00Z RUNS SUGGEST SIMILAR TIMING TODAY AND INTENSITY...BUT MAYBEA
BIT WIDER BAND.
A BREAK OCCURS LATE TODAY AND THIS EVENING...BUT HAVE INCREASED
THE SNOW CHANCES TONIGHT WITH ANOTHER 1-2 INCHES NOW EXPECTED
ALONG AND NORTH OF I-90. SECONDARY SHORTWAVE TROUGH RIDING ON THE
NOSE OF THE POLAR JET WILL COME ACROSS THE AREA TONIGHT...A DIRECT
HIT. SO...SNOWFALL SHOULD BREAK OUT AGAIN ALONG AND NORTH OF I-90
AROUND MIDNIGHT...WITH AREAS SOUTH A BIT MORE LIMITED IN THEIR
SATURATION. THE ENERGY WILL SHIFT EAST BY SUNRISE. MODEL GUIDANCE
HAS SOME SPREAD ON THE LOCATION OF THE SNOW WITH SOME SOLUTIONS
FURTHER SOUTH...BUT IT SEEMS THE TRACK OF THE WAVE AND THE JET
FLOW ALOFT WOULD SHOW PREFERENCE TO THE I-90 CORRIDOR AND NORTH.
NEW SNOW TOTALS BY TUESDAY MORNING WILL BE IN THE 1-3 INCH RANGE
WITH THE 3 INCH TOTALS MOST LIKELY ALONG AND NORTH OF I-94. HAVE
COLLABORATED WITH SURROUNDING NWS OFFICES AND WILL HOLD OFF ON THE
ADVISORY AS THE TWO SYSTEMS SHOULD BE SPACED IN TIME...AND THE 3
INCH TOTALS SHOULD BE THE HIGHER END RATHER THAN THE RULE. WILL
COVER IT IN THE HAZ WEATHER OUTLOOK AND POSSIBLY A SPECIAL
STATEMENT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 329 AM CST MON DEC 16 2013
TUESDAY LOOKS TO BE A BREEZY DAY BEHIND THIS WAVE...IN THE 15-25
MPH RANGE. THEN...RIDGE BUILDING STARTS WITH MAINLY SUNSHINE
EXCEPT ACROSS THE NORTH WHERE THE STORM TRACK SHIFT TO. A STRONG
SHORTWAVE TRAVELS ALONG THE U.S. CANADA BORDER AND MORE WARM
ADVECTION IS EXPECTED TUESDAY NIGHT AND WEDNESDAY NIGHT...WITH
PRECIPITATION STILL OFF TO THE NORTH.
THURSDAY-SUNDAY...
SIGNALS CONTINUE IN THE MODEL GUIDANCE FOR PRECIPITATION TO
SPREAD IN LATE THURSDAY AND THURSDAY NIGHT WITH THE FIRST
SHORTWAVE TROUGH EJECTION FROM THE LONGWAVE DEVELOPING ACROSS THE
WRN CONUS. THE SIGNAL IS REMAINING CONSISTENT WITH THE GFS AND GFS
ENSEMBLES STILL THE COLDER SOLUTIONS...WITH THE FRONTAL BOUNDARY
REMAINING THROUGH IL AND THE SOUTHERN FORECAST AREA IN SUB-ZERO
SURFACE TEMPERATURES. ACROSS ABOUT THE SOUTHERN TWO-THIRDS...THE
LIFT APPEARS LIMITED WITH ABUNDANT MOISTURE IN THE 0-3KM
LAYER...BUT NOT ABOVE IN THE ICE PRODUCING LAYER. THUS THE GFS HAS
A 3KM DEEP SUPERCOOLED LIQUID LAYER...CONSISTENT OVER THE PAST
RUNS. THIS IS A FZDZ/FZRA SITUATION AND HOLD THE POTENTIAL FOR
ICING. THE WARMER SOLUTIONS OF THE ECMWF/CANADIAN MODELS WOULD
CAUSE RAIN IN THE SOUTH. THE SPREAD IN THE TEMPERATURE PROFILE IS
STILL VERY LARGE THURSDAY/THU NIGHT AMONG THE WARM VERSUS COLD
SOLUTIONS...WITH SURFACE HIGHS 28F IN THE GFS THURSDAY...AND 45F
IN THE CANADIAN MODEL...WITH THE 16.00Z ECMWF IN THE MIDDLE. THAT
IS WHERE OUR FORECAST TEMPERATURES REMAIN...THUS A MORE LIMITED
ICING AREA IN NERN IA AND SWRN WI...AND AMOUNTS HAVE TRENDED
LOWER...LESS THAN 0.10 INCHES.
TO THE NORTH ON THURSDAY NIGHT IT APPEARS THE NORTHERN STREAM WAVE
WILL PROVIDE ENOUGH FORCING FOR DEEP SATURATION AND LIGHT SNOWFALL
THAT WOULD ACCUMULATE AROUND AN INCH. CURRENT FORECAST HAS THIS
LIQUID VERSUS SNOW OUTCOME ALONG A KMCW-KISW LINE...WITH SNOW
NORTHWEST. OVERALL...DID RAISE PRECIPITATION CHANCES BUT OVERALL
CHANGES WERE MINOR WITH THAT SYSTEM.
THE LONGWAVE TROUGH DIGS DEEPLY INTO MEXICO ON THE WEEKEND AND THERE
IS HIGH SPREAD ON THE OUTCOMES FOR THIS MAJOR ENERGY. THERE WILL BE
MAJOR WINTER WEATHER WITH THIS SYSTEM...BUT THE FURTHER SOUTH IT
DIGS...THE MORE THE AREA WOULD SEEM TO REMAIN UNDER THE NRN
STREAM OF ENERGY AND NOT BE AFFECTED. HAVE SMALL CHANCES OF
PRECIPITATION IN THE FORECAST FOR NOW MAINLY FOR E/SE AREAS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1158 AM CST MON DEC 16 2013
CURRENTLY WATCHING A TROUGH OF LOW PRESSURE AND ASSOCIATED N-S
BAND OF MODERATE TO OCCASIONALLY HEAVY SNOW MOVING EAST ACROSS THE
MISSISSIPPI RIVER AT THIS TIME. SNOW SHOULD END AT KRST BY 20Z AND
AT KLSE BY 22Z WITH CIGS/VIS IMPROVING INTO MVFR CATEGORY. PLAN ON
MVFR STRATOCUMULUS TO LINGER INTO THIS EVENING.
ANOTHER FAIRLY POTENT TROUGH OF LOW PRESSURE IS POISED TO IMPACT
THE AREA AFTER MIDNIGHT WITH ANOTHER ROUND OF LIGHT TO MODERATE
SNOW WITH VIS/CIGS DROPPING BACK INTO IFR/TEMPO LIFR CATEGORY IN
THE 07-11Z TIME FRAME. IN ADDITION...LOOKS LIKE THIS TROUGH WILL
BRING SOME GUSTY NORTHWEST WINDS BEHIND IT. PLAN ON NORTHWEST
WINDS IN THE 20-30KT RANGE AT KRST AFTER 11Z...AND AT KLSE AFTER
12Z. THESE WINDS OVER A FALLING/FRESH SNOW IS EXPECTED TO PRODUCE
SOME BLOWING SNOW ACROSS THE OPEN AREAS OF SOUTHEAST MN...INLUDING
KRST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...DAS