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. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
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 VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
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. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
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