Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/24/13


AREA FORECAST DISCUSSION
NWS ALBANY NY
144 PM EST TUE JAN 22 2013 .SYNOPSIS... COLD TEMPERATURES WILL CONTINUE THROUGH THE UPCOMING WORK WEEK...AS AN ARCTIC AIR MASS SETTLES OVER THE REGION. BITTER COLD IS EXPECTED ACROSS THE REGION TODAY THROUGH THURSDAY. LOW PRESSURE MAY BRING WIDESPREAD SNOW TO THE REGION ON FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 130 PM...POLAR VORTEX CONTUINUES TO SPIN ACROSS AREA. -41C AT 500MB ON RUC ANALYSIS. KENX VAD WIND PROFILE SHOWS 15-30KTS WIND BETWEEN 2000 AND 7000 FEET MSL...SO CONTINUED BREEZY CONDITIONS EXPECTED. SUNS RADIATION COMBINED WITH COLD AIR ALOFT HAS LED TO CONVECTIVE CLOUDS COVERING A GOOD PART OF AREA. LAKE EFFECT BAND ALSO NOW POINTED RIGHT DOWN MOHAWK VALLEY...BUT VERY WEAK RETURNS...SO LIGHT SNOW AT WORST SOUTHERN HERKIMER COUNTY WITH FLURRIES FURTHER SOUTHEAST. TEMPS ARE COLD WITH SINGLE DIGITS IN THE HIGHER TERRAIN TO AROUND 20 IN THE HUDSON VALLEY. LITTLE CHANGE EXPECTED THROUGH SUNSET. THIS UPDATE CONTAINS COMPLETE REFRESH OF DATABASE THROUGH 7 AM FRIDAY MORNING. FIRE WEATHER GRIDS ALSO UPDATED. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... WIND CHILL ADVISORIES AND WARNINGS ARE IN EFFECT FOR TONIGHT AND WEDNESDAY. WIND CHILL VALUES WILL VARY CONSIDERABLY FROM LOCATION TO LOCATION...AND NOT ALL AREAS WITHIN EACH COUNTY WILL SEE THE WIND CHILLS REACH ADVISORY OR WARNING CRITERIA. LAKE EFFECT SNOW SHOWER ACTIVITY SHOULD CONTINUE TONIGHT...THEN GRADUALLY DIMINISH WEDNESDAY THROUGH WEDNESDAY NIGHT. SOURCES OF GUIDANCE SUGGEST BOUNDARY LAYER WINDS STAY RELATIVELY STRONG AND SHOULD MIX TO THE SURFACE PERIODICALLY THROUGH TONIGHT... ESPECIALLY IN HIGHER ELEVATIONS AND THROUGH THE MOHAWK VALLEY WITH CHANNELING EFFECTS. WIND CHILL WARNINGS IN EFFECT FOR THE SOUTHERN ADIRONDACKS. WIND CHILLS SHOULD RISE TO ADVISORY RANGE THROUGH WEDNESDAY MORNING FOR THE SOUTHERN ADIRONDACKS..BUT TO AVOID CONFUSION...JUST KEEPING THE ONE HEADLINE AND EXPLAINING THE WIND CHILL TRENDS IN THE WSW. WIND CHILL ADVISORIES IN EFFECT FOR THE WESTERN MOHAWK VALLEY...SCHOHARIE VALLEY...EASTERN CATSKILLS...LAKE GEORGE AND NORTHERN SARATOGA REGION...SOUTHERN VERMONT AND WESTERN MASSACHUSETTS. THE WIND CHILLS SHOULD RISE OUT OF WIND CHILL ADVISORY CRITERIA BY NOON WEDNESDAY...EVEN WITH POTENTIALLY BREEZY CONDITIONS AT TIMES THROUGH THE DAY. THERE COULD BE ADDITIONAL WIND CHILL HEADLINES NEEDED WEDNESDAY NIGHT...BUT WILL TREAT THAT AS A SEPARATE EVENT IF NECESSARY AND THOSE DECISIONS WILL BE MADE LATER TODAY OR TONIGHT. TEMPERATURES ARE A LITTLE TRICKY. WITH SUCH AN ARCTIC AIR MASS... USUALLY TEMPERATURES FALL BELOW GUIDANCE VALUES THROUGH THE PERIOD. HOWEVER...WITH STEADY AND RELATIVELY STRONG BOUNDARY LAYER WEST TO NORTHWEST FLOW...WITH WINDS OCCASIONALLY MIXING DOWN... EVEN AT NIGHT...MIXING COULD PREVENT TEMPERATURES FROM BEING AS COLD AS THEY COULD BE. ALSO...CENTER OF THE SURFACE HIGH PRESSURE QUITE A DISTANCE WEST OF OUR REGION AND MAXIMUM SUBSIDENCE MAY NOT AFFECT OUR REGION UNTIL LATE WEDNESDAY NIGHT...THURSDAY AND THURSDAY NIGHT. IN ADDITION...INLAND EXTENT OF LAKE EFFECT CLOUDS IN QUESTION...WHICH CAN PREVENT TEMPERATURES FROM BEING AS COLD AS THEY COULD BE. ALSO...NOT MUCH SNOW PACK TO AID IN STEEP TEMPERATURE DROPS. WITH THESE UNCERTAINTIES...STAYING CLOSE TO COLDEST GUIDANCE BUT NOT READY TO GO MUCH BELOW GUIDANCE THROUGH THE PERIOD UNTIL THE EXTENT OF THE WINDS AND LAKE EFFECT CLOUDS CAN BE DETERMINED BEYOND TODAY AND TONIGHT. STILL...WE CAN EXPECT THE COLDEST AIR OF THE WINTER SO FAR. HIGHS IN THE TEENS WEDNESDAY....WITH SINGLE NUMBER IN HIGHER ELEVATIONS. HIGHS THURSDAY JUST A FEW DEGREES WARMER THAN WEDNESDAY...IF THAT...DEPENDING ON WHETHER BOUNDARY LAYER TEMPERATURES CAN WARM A DEGREE OR TWO. LOWS WELL BELOW ZERO IN NORTHERN AREAS AND HIGHER ELEVATIONS...ZERO TO 10 IN THE HUDSON RIVER VALLEY AND SOUTHERN AREAS. && .LONG TERM /FRIDAY THROUGH MONDAY/... THE MAIN FORECAST CHALLENGE FOR THE PERIOD IS A POSSIBLE LIGHT TO MODERATE SNOW EVENT FOR MUCH OF THE FORECAST AREA FRIDAY THROUGH FRIDAY NIGHT. VARIOUS SOURCES OF MODEL GUIDANCE HAVE SHOWN DIFFERENCES AMONG EACH OTHER AND WITHIN THEMSELVES FROM RUN TO RUN. WILL LEAN MORE TOWARDS THE ECMWF/GGEM CAMP AND AWAY FROM THE GFS FOR THIS FORECAST. THE GFS HAS BEEN MORE INCONSISTENT AND IS NOW DEPICTING MORE OF A WEAKER NORTHERN STREAM SYSTEM MOVING ACROSS THE GREAT LAKES AND NORTHEAST...WHILE THE ECMWF/GGEM INDICATE SOUTHERN STREAM ENERGY EMERGING FROM THE TENNESSEE/OHIO VALLEY REGIONS AND POSSIBLY PHASING INTO A STRONGER SYSTEM NEAR THE SOUTHERN NEW ENGLAND COAST. THE LATEST ECMWF HAS A NEW WRINKLE IN THAT IS HAS EXPLOSIVE CYCLOGENESIS OCCURRING SATURDAY MORNING. SHOULD THE ECMWF SOLUTION OCCUR...WE WOULD BE DEALING WITH A HEAVIER SNOW EVENT. HOWEVER...THERE ARE QUITE A FEW VARIABLES TO CONSIDER AT THIS TIME. ALL INDICATIONS ARE FOR AT LEAST THE SAME PTYPE OF SNOW WITH TEMPS CONTINUED COLD. STILL PLENTY OF TIME TO SORT OUT THE DETAILS...AND IT NOW LOOKS LIKE ONSET OF SNOW WOULD BE DELAYED UNTIL FRIDAY AFTERNOON. WITH UNCERTAINTY IN THE DEGREE/POSITION OF COASTAL DEVELOPMENT...HAVE PAINTED THE HIGHEST POPS ACROSS SOUTHERN AREAS. WILL LINGER CHANCE POPS INTO SATURDAY NOW FOR THE POSSIBILITY OF A STRONGER AND SLOWER CYCLONE. MODELS ARE IN GOOD AGREEMENT SHOWING DRY N-NW FLOW BEHIND THE DEPARTING SYSTEM FOR SATURDAY NIGHT INTO SUNDAY WITH BRISK WINDS AND CONTINUED BELOW NORMAL TEMPERATURES. IT LOOKS LIKE THE SURFACE RIDGE WILL GRADUALLY MOVE ACROSS THE AREA THROUGH EARLY NEXT WEEK WITH A MODERATING TREND. TEMPERATURES MAY WARM BACK TO NORMAL BY MONDAY. THERE DOES NOT APPEAR TO BE MUCH OF A CHANCE FOR ANY PRECIP DURING THIS TIME WITH HIGH PRESSURE MAINLY IN CONTROL. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD ENDING AT 18Z ON WEDNESDAY. SCT-BKN STRATOCU CLOUDS FROM LAKE EFFECT ACTIVITY WELL TO THE WEST WILL WANDER ACROSS THE REGION THROUGH THE EVENING HOURS. WHILE NO SNOW SHOWERS ARE EXPECTED AT THE TERMINALS...SOME LEFT OVER CLOUDS WILL OCCUR FROM TIME TO TIME. IN ADDITION...W-NW WINDS WILL BE GUSTY THROUGH THE EVENING HOURS...WITH A FEW GUSTS TO AROUND 25 KTS...MAINLY FOR KPSF/KALB. WINDS WILL DIMINISH THIS EVENING...WITH FEW-SCT STRATOCU CONTINUING. THE INVERSION HEIGHT WILL SLOWLY LOWER BY WEDNESDAY MORNING...BUT FLYING CONDITIONS WILL STILL REMAIN VFR. WEST WINDS OF 5-10 KTS WILL CONTINUE OVERNIGHT. DURING DAYTIME MIXING ON WEDNESDAY...WIND SPEEDS WILL INCREASE WITH WINDS OF 10-15 KTS AND A FEW HIGHER GUSTS. SCT CU/STRATOCU WILL CONTINUE TO BE AROUND ON WEDNESDAY AT 3-4 KFT. OUTLOOK... WED PM-FRI AM...VFR. NO SIG WX. FRI PM-SAT...MVFR/IFR. CHC -SN. SUN...VFR. NO SIG WX. && .HYDROLOGY... PRECIPITATION THAT FALLS OVER THE NEXT FIVE DAYS IS EXPECTED TO BE IN THE FORM OF SNOW AS AN ARCTIC AIR MASS SETTLES IN. TEMPERATURES WILL AVERAGE WELL BELOW NORMAL DURING THE UPCOMING WEEK. THE PERSISTENT COLD WILL CAUSE ICE TO FORM ON MOST BODIES OF WATER. THERE IS THE POSSIBILITY FOR FREEZE UP ICE JAMS TO OCCUR ON SMALL STREAMS IN NORTHERN AREAS. THIS COULD RESULT IN SOME MINOR LOCALIZED FLOODING. 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. && .CLIMATE... WE ARE AT THE CLIMATOLOGICAL COLDEST TIME OF THE YEAR FOR OUR AREA. NORMAL TEMPERATURES FOR JANUARY 22ND THROUGH 24TH: ALBANY: HIGHS AROUND 30. LOWS IN THE MID TEENS. GLENS FALLS: HIGHS IN THE UPPER 20S. LOWS IN THE SINGLE DIGITS. POUGHKEEPSIE: HIGHS IN THE MID 30S. LOWS IN THE MID TEENS. BENNINGTON: HIGHS AROUND 30. LOWS NEAR 10. PITTSFIELD: HIGHS IN THE UPPER 20S. LOWS NEAR 10. RECORD LOWS FOR ALBANY (DAILY RECORDS DATE BACK TO 1874) JANUARY 22ND... -20 DEGREES 1984 JANUARY 23RD... -20 DEGREES 1970 JANUARY 24TH... -17 DEGREES 1948 && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...WIND CHILL ADVISORY FROM 7 PM THIS EVENING TO NOON EST WEDNESDAY FOR NYZ038-041-043-047-058-063-082-083. WIND CHILL WARNING FROM 7 PM THIS EVENING TO 6 PM EST WEDNESDAY FOR NYZ032-033-042. MA...WIND CHILL ADVISORY FROM 7 PM THIS EVENING TO NOON EST WEDNESDAY FOR MAZ001-025. VT...WIND CHILL ADVISORY FROM 7 PM THIS EVENING TO NOON EST WEDNESDAY FOR VTZ013>015. && $$ SYNOPSIS...SND/NAS NEAR TERM...SND/FRUGIS SHORT TERM...NAS LONG TERM...JPV AVIATION...FRUGIS HYDROLOGY...GJM/JPV CLIMATE...ALY
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
948 PM EST WED JAN 23 2013 .SYNOPSIS... A WEAK AREA OF LOW PRESSURE WILL QUICKLY DEVELOP EAST OF THE NORTH CAROLINA COAST EARLY THURSDAY. HIGH PRESSURE THEN BUILDS IN FOR LATE THURSDAY AND FRIDAY MORNING, BEFORE MOVING OFFSHORE. A WEAK AREA OF LOW PRESSURE SLIDES ACROSS THE MID ATLANTIC FRIDAY NIGHT, THEN INTENSIFIES AS IT TRACKS TOWARD THE CANADIAN MARITIMES THROUGH SATURDAY. AN EXPANSIVE AREA OF HIGH PRESSURE BUILDS INTO OUR REGION THIS WEEKEND, THEN SHIFTS OFFSHORE EARLY NEXT WEEK. A WARM FRONT LOOKS TO LIFT TO OUR NORTH LATE MONDAY INTO TUESDAY, WITH A COLD FRONT ARRIVING FROM THE WEST DURING WEDNESDAY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... 930 PM ESTF HAS USED LATEST AVBL HPC GRIDS WHICH THE 00Z/24 NAM AND LATEST AVBL RAP MIRRORS. STARTS WITH MO CLR SKIES ACROSS A GOOD CHUNK OF THE FCST AREA THIS EVENING BEFORE SKIES CLOUD OVER LATE. WE HAVE ALMOST 1.5 INCHES ALONG THE S BORDER OF SUSSEX COUNTY DE TAPERING TO TRACE JUST N OF KDOV TO KWWD. THERE MAY BE SOME OCEAN EFFECT ENHANCEMENT ALONG THE SE SUSSEX COUNTY BORDER NEAR DAWN AS -12C 950 MB TURNS EAST NE FOR A SHORT TIME. OTRW MULTI MODEL AGREEMENT ON A 2 TO 8 HOUR PERIOD OF SNOW FOR S DE AND ADJACENT WATERS/MD. HOW FAR NORTH...FLUFF FACTOR ETC DETERMINE FINAL AMTS. EVENT IS MOSTLY 06Z-12Z. LOW TEMPS NEAR 5 BELOW IN SOME OF THE SNOW COVERED FAR NORTH TO NEAR 20 FAR SOUTH. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... LOW PRESSURE TO THE EAST WILL DEEPEN THURSDAY AS HIGH PRESSURE BUILDS IN FROM THE WEST. ANY SNOW ASSOCIATED WITH THE LOW WILL BE EAST OF THE AREA BY MORNING...SO DRY WEATHER IS EXPECTED. WINDS WILL BE GUSTY 25 TO 30 MPH DURING THE DAY...AND WITH TEMPERATURES IN THE TEENS EARLY ON...THERE MAY STILL BE SOME COLD WIND CHILL READINGS EARLY ON. TEMPERATURES WILL MODERATE INTO THE 20S BY AFTERNOON....STILL ABOUT 15 DEGS COLDER THAN NORMAL! MILKY WHITE MIDDAY SKY AS VERY LARGE T1-T5 LAPSE RATES WRING OUT REMAINING BL MOISTURE FORMING LOTS OF VIRGA DURING THE MIDDAY HOURS BEFORE DRIER AIR PREVAILS AND EVAPORATES THE VIRGA. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... THE STRETCH OF RATHER COLD CONDITIONS CONTINUES INTO THE WEEKEND, HOWEVER THEN A BREAK LOOKS TO OCCUR ESPECIALLY EARLY NEXT WEEK. A QUICK MOVING SYSTEM LATER FRIDAY AFTERNOON AND NIGHT SHOULD BRING AT LEAST SOME ACCUMULATING SNOW TO THE AREA. THE OVERALL LARGE SCALE FLOW IS COMPRISED OF A POLAR VORTEX THAT TENDS TO RELAX SOME WITH TIME. AS THIS OCCURS, ADDITIONAL SHORT WAVE ENERGY TOPPING THE RIDGE OUT WEST DIVES SOUTHEASTWARD ACROSS THE NORTHERN PLAINS AND HELPS TO CARVE OUT ANOTHER UPPER-LEVEL TROUGH. THE OVERALL FLOW REGIME IS SUPPORTIVE OF PROGRESSIVE SYSTEMS. THE NORTHERN AND SOUTHERN STREAM ENERGY HAS BEEN CAUSING ADJUSTMENTS IN THE MODEL GUIDANCE, HOWEVER GIVEN THE SETUP A QUICK MOVING AND WEAK SYSTEM IS ANTICIPATED BEFORE IT STRENGTHENS OFFSHORE ON SATURDAY. IN SUPPORT OF THIS IS THE UPPER-LEVEL TROUGH IS FORECAST TO BE EITHER NEUTRAL OR POSITIVELY TILTED. THERE DOES APPEAR TO BE MORE OF A CONSENSUS NOW WITH THIS SYSTEM GENERALLY ZIPPING ACROSS THE MID ATLANTIC STATES FRIDAY NIGHT. THE SURFACE LOW THEN STRENGTHENS ONCE OFFSHORE AS IT ENCOUNTERS MORE ENERGY INTERACTION ALONG WITH A MUCH MORE IMPROVED BAROCLINIC REGION OVER THE OCEAN. A SHOT OF COLD AIR THEN ARRIVES IN THE WAKE OF THIS WEAK STORM, WITH SOME AIRMASS MODIFICATION TAKING PLACE EARLY NEXT WEEK. WE USED A MODEL BLEND/CONTINUITY FROM THURSDAY NIGHT INTO SATURDAY, THEN INCORPORATED HPC GUIDANCE THEREAFTER. HPC USED MOSTLY A BLEND OF THE ECMWF MEAN/GEFS MEAN SATURDAY NIGHT THROUGH WEDNESDAY. SOME TWEAKS WERE THEN MADE BASED ON ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES. FOR THURSDAY NIGHT...A FAIRLY STRONG AREA OF HIGH PRESSURE SETTLES IN AND THIS MAY SET THE STAGE FOR A VERY COLD NIGHT AS WINDS DECOUPLE. SOME CLOUDS MAY START TO INCREASE, HOWEVER AS OF NOW THIS SHOULD BE MAINLY THE HIGH LEVEL VARIETY. WE THEN TURN OUR ATTENTION TO THE WEST AND SOUTHWEST FOR OUR NEXT SYSTEM. FOR FRIDAY AND SATURDAY...WHILE A STORM IS EXPECTED TO IMPACT THE REGION, IT IS ANTICIPATED TO BE WEAK AND A QUICK MOVER. THE OVERALL PROGRESSIVE FLOW SHOULD TEND TO KEEP THE LARGE SCALE LIFT ON THE WEAKER SIDE BEFORE THE SURFACE LOW STRENGTHENS OFFSHORE AND MOVES AWAY. WHILE THERE STILL REMAINS SOME UNCERTAINTY IN THE DETAILS, THERE IS BETTER CONSENSUS THAT A LIGHT QPF EVENT MOVES ACROSS THE ENTIRE CWA. THE NAM CONTINUES TO APPEAR TO QUICK AND LIES ON THE EAST SIDE OF THE MODEL SPREAD BY SATURDAY MORNING IN THE WESTERN ATLANTIC. SINCE THERE IS NORTHERN AND SOME SOUTHERN STREAM ENERGY INVOLVED, THE PROGRESSIVE NATURE OF THE FLOW TENDS TO KEEP THE LARGE SCALE LIFT IN CHECK FOR AWHILE. THE GENERAL IDEA OF INCREASING WAA WILL HELP TO SPREAD OUT AN AREA OF LIGHT TO PERHAPS SOME EMBEDDED MODERATE SNOW. THE AIRMASS IS RATHER DRY TO START, BUT THE FORECAST SOUNDINGS OVERALL SUGGEST THAT THE SATURATION OCCURS FAIRLY QUICKLY DURING FRIDAY AFTERNOON. WE SHOULD LOSE SOME QPF TO EVAPORATION, BUT THE LIGHT SNOW MAY START FAIRLY QUICKLY THEREAFTER. WE CONTINUE TO PLAY THIS IS AN OVERRUNNING EVENT FOR MOST OF THE DURATION AS THE INITIAL WAA HELPS TO TIGHTEN THE THERMAL GRADIENT ALOFT, ALTHOUGH THIS IS NOT ROBUST ENOUGH TO GET MUCH IN THE WAY OF FRONTOGENETIC FORCING GOING. MODEL CROSS SECTIONS SHOW THE SNOW GROWTH REGION EDGING INTO THE LIFT AREA /SATURATION OCCURRING THROUGH THE DENDRITIC CRYSTAL LAYER/, HOWEVER THIS IS ON THE WEAKER SIDE. THIS ALL POINTS TO A LOW BANDING POTENTIAL UNTIL ONCE THE SURFACE LOW IS OFFSHORE AND MOVING AWAY AS IT STRENGTHENS. AT LEAST ONE CONCERN IS THAT AS THE MAIN SURFACE LOW STRENGTHENS OFFSHORE, DOES THIS CREATE A VOID OR MUCH WEAKER AREA OF LIFT TO ITS NORTHWEST SIDE. THIS IS A POSSIBILITY BUT FOR NOW IT IS NOT FACTORED IN AS IT APPEARS THAT A SWATH OF MAINLY LIGHT SNOW MOVES ACROSS THE ENTIRE AREA. WE SLOWED DOWN THE POPS A BIT MORE FROM WEST TO EAST DURING THE DAY FRIDAY AS THE MAIN SYSTEM LOOKS TO ARRIVE LATER IN THE AFTERNOON. IF THE GUIDANCE CONSENSUS HOLDS, POPS CAN BE INCREASED INTO THE CATEGORICAL RANGE. REGARDING PRECIPITATION TYPES, THE AIRMASS LOOKS PLENTY COLD AND GIVEN THE DRYNESS LEADING UP TO IT WE WILL MAINTAIN ALL SNOW THROUGHOUT. WHILE THE AIRMASS MOISTENS UP, THE FORECAST SOUNDINGS ARE STILL RATHER COLD WHICH WOULD TEND TO LEAD TOWARD HIGHER RATIOS. THE EVENT THAT TOOK PLACE THIS PAST MONDAY EVENING IN PARTS OF OUR CWA HAD RATHER HIGH RATIOS /ALSO STRONG FRONTOGENETIC FORCING WITH BANDING/ AND WHILE WE ARE NOT THINKING THEY WILL BE THIS HIGH FOR THIS EVENT, ABOUT 20 TO 1 IS CERTAINLY DOABLE. SINCE THERE IS WEAKER FORCING AND A LESS OF A CHC FOR BANDING, THE SNOWFALL RATES ARE ANTICIPATED TO BE ON THE LIGHT SIDE. BASED ON THE QPF CONSENSUS, WE ARE LEANING TOWARD A GENERAL 1-3 INCH SNOWFALL ACROSS THE AREA. WHILE THIS IS NOT A LOT, IT COULD CREATE SOME HAZARDOUS TRAVEL FOR A TIME AS THE AIR AND GROUND IS COLD. WE WILL CONTINUE TO MENTION THIS SYSTEM IN THE HAZARDOUS WEATHER OUTLOOK. THE SYSTEM MOVES AWAY DURING SATURDAY MORNING WITH A COLD AND GUSTY NORTHWESTERLY WIND IN ITS WAKE. THERE COULD BE SOME FLURRIES OR SNOW SHOWERS MAINLY IN THE POCONOS DUE TO SOME EASTERN GREAT LAKES RESPONSE. FOR SUNDAY AND MONDAY...AN EXPANSIVE SURFACE HIGH BUILDS ACROSS OUR AREA SUNDAY BEFORE SETTLING TO OUR SOUTH INTO MONDAY. A NORTHWESTERLY FLOW IS FORECAST TO BE MAINTAINED SUNDAY BEFORE BACKING MORE TO THE WEST AND EVEN SOUTHWEST MONDAY. THIS WILL RESULT IN AT LEAST SOME WAA OCCURRING AS THE MAIN TROUGH WEAKENS AND ALLOWS SOME WARMING TO ARRIVE FROM THE OHIO VALLEY. THERE MAY HOWEVER BE A WEAK DISTURBANCE ARRIVING PRIOR TO THE RIDGE MONDAY WITHIN THE FLOW AS THE WAA TO THE WEST HELPS TO INCREASE THE THERMAL GRADIENT ALOFT. THIS WILL ALSO AID IN THE DEVELOPMENT OF A WARM FRONT. SOME OF THE GUIDANCE INDICATING A PERIOD OF OVERRUNNING PRECIPITATION MONDAY AND MONDAY NIGHT AS THE WARM FRONT ARRIVES. THIS COULD FEATURE A LITTLE SNOW TO PERHAPS A WINTRY MIX DEPENDING ON THE THERMAL PROFILES. FOR NOW, WE DID NOT HIT THIS ALL THAT HARD GIVEN THE BULK OF THE ENERGY LOOKS TO BE FARTHER TO THE WEST AND IT MAY DAMPEN OUT AS IT SHIFTS EASTWARD. FOR TUESDAY...HIGH PRESSURE IS FORECAST TO BE CENTERED OFF THE SOUTHEASTERN U.S. COAST WITH AN UPPER-LEVEL RIDGE ARRIVING ALONG THE EAST COAST. THIS WILL GENERALLY BE ENHANCED AS LOW PRESSURE TRACKS ACROSS THE GREAT LAKES REGION WITH A WARM FRONT LIFTING TO OUR NORTH. THIS FRONTAL BOUNDARY THOUGH MAY REMAIN DRAPED NEARBY AS HIGH PRESSURE TRAVERSES SOUTHEASTERN CANADA. FOR NOW, KEPT A DRY FORECAST GOING FOR TUESDAY THEN BROUGHT IN SOME LOW CHC POPS AT NIGHT AS WE AWAIT FOR THE MAIN COLD FRONT TO GET CLOSER. A SOUTHERLY FLOW ALONG WITH WAA SHOULD RESULT IN MILDER SURFACE TEMPERATURES. FOR WEDNESDAY, CONTINUED WAA AHEAD OF A COLD FRONT SHOULD ALLOW FOR A MILDER DAY ALTHOUGH THIS MAY BE MUTED SOME BY SOME SHOWERS POTENTIALLY ARRIVING. IT APPEARS THE COLD FRONT ARRIVES BY LATE IN THE DAY. FOR NOW, INCLUDED LOW CHC POPS ACROSS THE REGION. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THROUGH THURSDAY...OCNL VFR CIGS THROUGH EARLY THURSDAY MORNING WITH A GENERAL NNW WIND UNDER 15 KT THRU THE NIGHT. A 2 TO 8 HOUR PERIOD OF SNOW VCNTY KDOV SOUTHWARD IN S DE LATE TONIGHT. THU AFTER 15Z...VFR SCT CLOUDS AOA 5000 FT AND A NW WIND G NEAR 25 KTS WITH PLENTY OF VIRGA AND AREAS OF BKN CIGS NEAR 5000FT FORENOON EVENTUALLY BECOMING CLEAR BY 21Z. OUTLOOK... THURSDAY NIGHT...VFR. WEST TO NORTHWEST WINDS 15 TO 20 KNOTS WITH GUSTS TO AROUND 25 KNOTS, DIMINISHING TO AROUND 10 KNOTS. FRIDAY...VFR THROUGH ABOUT MID AFTERNOON. MVFR CEILINGS AND VISIBILITIES SHOULD DEVELOP AS SNOW ARRIVES GENERALLY WEST OF THE DELAWARE RIVER THROUGH SUNSET. FRIDAY NIGHT...MVFR CEILINGS AND VISIBILITIES THROUGH ABOUT 06Z SATURDAY. LOCAL IFR VISIBILITIES ARE POSSIBLE FOR A TIME, ESPECIALLY EAST OF THE DELAWARE RIVER. DESPITE SOME LOWER CONFIDENCE, IT APPEARS A GENERAL 1 TO 3 INCHES OF SNOW OCCURS ACROSS THE ENTIRE AREA. THE SNOW IS ANTICIPATED TO BE RATHER FLUFFY GIVEN THE VERY COLD AND DRY AIR IN PLACE. SATURDAY...MAINLY VFR. WEST TO NORTHWEST WINDS 15 TO 20 KNOTS WITH GUSTS UP TO 30 KNOTS. SUNDAY AND MONDAY...VFR. NORTHWEST WINDS SUNDAY AROUND 10 KNOTS, BECOMING LIGHT AT NIGHT. LIGHTER WINDS ON MONDAY HOWEVER PROBABLY TURNING SOUTHERLY. && .MARINE... DESPITE THE G NEAR 25 KTS AT 44065 NO SCA AS ALL OTHER REPORTING SITES NEAR THE CW ARE UNDER 20 KTS. LIGHT FREEZING SPRAY CONTINUES AT THE 4 MONITORING LOCATIONS IN OUR WATERS NEAR 00Z. NEXT SCA DEVELOPS THU MORNING UNTIL 05Z FRIDAY. CONDITIONS ARE CLOSE TO GALE GUSTS MIDDAY THU AND THU AFTN...BUT CONFIDENCE IN GALE TOO LOW TO ISSUE ATTM. THERE IS A CHC FOR -SN OVER THE SRN COASTAL WATERS OVERNIGHT. THE MENTION OF LIGHT FREEZING SPRAY WILL REMAIN FOR TONIGHT AND THURSDAY. OUTLOOK... A TIGHTENED PRESSURE GRADIENT AHEAD OF AN EXPANSIVE AREA OF HIGH PRESSURE THURSDAY NIGHT WILL WEAKEN. A CONTINUED COLD AIR MASS WITHIN THE TIGHTENED PRESSURE GRADIENT ON THURSDAY WILL CONTINUE FOR A TIME DURING THE NIGHT. THIS WILL RESULT IN ADVISORY LEVEL GUSTS AT LEAST THROUGH THE EVENING. THEREAFTER, THE SURFACE HIGH SETTLES IN AND SHOULD LOWER THE WINDS. AS A RESULT, WE WILL GO WITH A SMALL CRAFT ADVISORY FOR ALL AREAS THROUGH 05Z FRIDAY. THE NEXT SYSTEM IS FORECAST TO MOVE THROUGH FAIRLY QUICKLY LATE FRIDAY AFTERNOON AND FRIDAY NIGHT. THIS SYSTEM WILL STRENGTHEN ONCE OVER THE ATLANTIC WATERS, WITH ANOTHER SHOT OF COLD AIR TO FOLLOW. ONCE AGAIN A TIGHTENING PRESSURE GRADIENT COMBINED WITH DEEPER MIXING WILL ALLOW FOR ADVISORY LEVEL WINDS OCCURRING LATE FRIDAY NIGHT AND ESPECIALLY SATURDAY. THERE ARE SOME DIFFERENCES REGARDING THE WINDS ABOVE THE SURFACE, AS THE GFS IS STRONGER AND WOULD HAVE A BETTER CHC OF A PERIOD OF GALE FORCE WINDS. AS OF NOW, LEANING MORE TOWARD A STRONG ADVISORY LEVEL EVENT SATURDAY. THE GRADIENT FLOW THEN DROPS OFF ENOUGH TO ALLOW WINDS TO DROP BACK BELOW SMALL CRAFT ADVISORY CRITERIA LATE SATURDAY NIGHT INTO SUNDAY. HIGH PRESSURE ARRIVES SUNDAY BEFORE SHIFTING TO OUR SOUTH AND EAST WITH A SOUTHERLY FLOW DEVELOPING. && .CLIMATE... TODAYS AVERAGE TEMPERATURE AT KMPO AND KPHL WAS THE COLDEST SINCE 1/24/11. AT KACY THE AVG TEMP COLDEST SINCE 1/16/09. TODAYS MAX TEMP AT MPO COLDEST SINCE 9F 1/17/09 TODAYS MAX TEMP AT ABE COLDEST SINCE 18F 1/17/09 TODAYS MAX TEMP AT PHL COLDEST SINCE 21F 1/30/10 TODAYS MAX TEMP AT ACY COLDEST SINCE 22F 1/30/10 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 AM THURSDAY TO MIDNIGHT EST THURSDAY NIGHT FOR ANZ430-431-450>455. && $$ SYNOPSIS...GORSE NEAR TERM...DRAG/O`HARA 948 SHORT TERM...DRAG/O`HARA LONG TERM...GORSE AVIATION...DRAG/GORSE/O`HARA 948 MARINE...DRAG/GORSE/O`HARA 948 CLIMATE...948
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
626 PM EST WED JAN 23 2013 .UPDATE/AVIATION... NR TERM MESOSCALE DVLPMNTS WARRANT AN EARLY UPDATE. IMPRESSIVE SW TROUGH DROPPING SWD OVR NRN WI YIELDING RAPID UPSTREAM LL VEERING ACRS LK MI AND RAPID COOLING OF CLD TOPS SEEN IN IR. COMPOSITE RADAR IMAGERY BLOSSOMING IN KIND AND NO DOUBT AUGMENTED W/SEEDER FEEDER MECHANISM IN PLACE INADV OF MID LVL SW. SHRT TERM RUC ALG W/LATEST 18Z HIGHRES GUIDANCE QUITE OMINOUS LTR THIS EVENING W/DVLPMNT OF INTENSE LK SNOW BANDS. AND UNLIKE LAST SVRL DAYS...MUCH IMPROVED THERMAL ENVIRONMENT W/DEEP...SATURATED ASCENT INDICATED IN WHAT SHLD EVOLVE TWD A LG INTENSE SINGLE BAND AFT MIDNIGHT. AS SUCH WILL JUMP ON EXPANDING ADVSY INTO LAPORTE COUNTY. CONTEMPLATED ADDING ST JOE TOO PER PLACEMENT OF SOME HIGHRES GUIDANCE HWVR THINK DEEPENING NRLY LL FLW COMPONENT WILL PUSH BAND WWD. REGARDLESS A SVRL HOUR BURST OF MOD-HVY SNOW XPCD FOR MUCH OF NW IN/SW MI AS THE EVENING GOES ON. WILL FURTHER MONITOR BAND EVOLUTION THROUGH THIS EVENING FOR POTENTIAL WARNING CRITERIA BEING MET. OTRWS FLIGHT CONDS OBVIOUSLY GOING DOWNHILL AT KSBN OVERNIGHT W/PRIMARILY IFR CONDS PREVAILING. SHRT PD OF MVFR CIGS AT KFWA XPCD THIS EVENING AS SFC TROUGH DROPS SWD BUT MAINLY VFR. && .PREV DISCUSSION... /ISSUED 337 PM EST WED JAN 23 2013/ SHORT TERM...THROUGH THURSDAY NIGHT. TWOFOLD FOCUS FOR THIS PACKAGE WITH AREA OF LIGHT SNOW FROM N ILLINOIS INTO SW PORTIONS OF THE CWA AND REINVIGORATE LAKE EFFECT POTENTIAL OVER THE NEXT 12 HOURS. RADAR/SFC OBS/SREF PRODUCTS ALL DEPICT AN AREA OF MID/UPPER LEVEL FORCING AND LEADING EDGE OF LFQ OF APPROACHING JET STREAK WITH THE S.W OF INTEREST FOR TONIGHT. THIS IS AIDING IN THE DEVELOPMENT OF A NARROW BAND OF ACCUMULATING SNOW ACROSS PORTIONS OF N/CNTRL IL. A FEW REPORTS OF OVER AN INCH HAVE BEEN NOTED WITH THIS FEATURE AS FAVORABLE DGZ SETUP HAS BEEN UNDERWAY. THIS FEATURE WAS TRACKING SE ACROSS THE SW PARTS OF THE FORECAST AREA WITH RADAR RETURNS INCREASING AND SOME FLURRIES BEING REPORTED. SOMEWHAT OF A WEAKENING TREND HAS BEEN NOTED AS THE AREA BUT STILL EXPECT THE SE TREND TO CONTINUE AND MAY GIVE A FEW TENTHS OF AN INCH OF SNOW AS IT PASSES. PREV UPDATE HAD BUMPED POPS TO LIKELY AND WILL LIKELY RUN WITH PRE 1ST PERIOD TO HANDLE. FOCUS THEN SHIFTS TO LAKE EFFECT FOR THE AREA. INITIAL ENERGY FROM THE SAME WAVE HAS ALLOWED FOR LAKE EFFECT TO EXPAND ACROSS MUCH OF NORTHERN BERRIEN COUNTY OVER THE PAST COUPLE OF HOURS. SOCIAL MEDIA REPORT OF 1 TO 2 INCHES OF NEW SNOW SEEN WITH MUCH LARGER SNOWFLAKES THAN EARLIER EVENT. THESE SNOW SHOWERS SHOULD CONTINUE AND WITH TIME EXPAND AS WAVE PASSES BY AND INCREASES LAKE EFFECT BAND COVERAGE AND INTENSITY AS WELL AS BEGINS TO ALLOW FOR TRANSIENT STATE TONIGHT. ALL HI RES MODELS STILL DEPICT AN INTERESTING SCENARIO TONIGHT WITH BANDS BECOMING MORE FOCUSED ACROSS CNTRL/S LWR MI AND EVENTUALLY DROPPING SOUTH AND WEST AS FLOW BECOMES MORE NW AND EVENTUALLY N OVERNIGHT. EAST AND SOUTH EXTENSION OF THE SNOW SHOWERS REMAINS TOUGH TO DETERMINE WITH SREF BRINGING A BURST OF LIGHT TO MODERATE SNOW TO MUCH OF THE NORTHERN HALF OF THE AREA LATE EVE INTO THE OVERNIGHT HOURS. NAM/RAP/WRF ALL KEEP THE ACTIVITY MORE CONFINED TO WITHIN A FEW COUNTIES INLAND. HAVE TRIED TO CAPTURE TRENDS THE BEST WITHOUT GOING OVERBOARD GIVEN HI BUST POTENTIAL ON EITHER SIDE. SEEING HOW MUCH FORCING HAS BEEN ASSOCIATED WITH THIS WAVE ALREADY AND A SMALL WINDOW OF SEMI FAVORABLE DGZ POSITIONING...COULD SEE SOME AREAS PICKUP A QUICK INCH OR TWO OF SNOW AS THE BAND PASSES. WENT WITH HPC QPF WHICH WAS REASONABLE AND ALIGNED NICELY WITH FAVORED LAKE EFFECT AREAS. GIVEN TRENDS SO FAR AND DISCUSSION WITH EVE SHIFT...WILL HESITANTLY DROP CASS COUNTY FROM THE ADVISORY. WHILE THEY MAY BE AFFECTED BY THE SNOWBAND FOR A PERIOD OF TIME THE OVERALL RISK SEEMS TO BE DIMINISHING WITH MAIN FOCUS FOR THE TIME BEING ON N BERRIEN COUNTY. BY THURSDAY MORNING...BAND WILL LIKELY BE ORIENTED NORTH TO SOUTH AND MOVING WEST AS FLOW BECOMES NE WITH TIME. IN ADDITION...A FEW OF THE HIGH RES MODELS SHOW A MESOLOW SETTING UP QUICKLY ACROSS N LK MI AND DROPPING SOUTH INTO S LK MI TOWARDS 12Z. HAVE ADJUSTED POPS TO REFLECT SLIGHTLY SLOWER TREND IN THE MORNING. CLEARING SKIES SHOULD RAPIDLY TAKE SHAPE IN THE MORNING EAST OF THE BAND. THIS WILL BE SHORT LIVED AS NORTHERN AND SOUTHERN STREAM ENERGY BEGIN TO CONVERGE ON THE AREA. DRY CONDITIONS SHOULD HOLD INTO MUCH OF THURS NGT BEFORE INCREASED FORCING MOVE IN FROM THE NW LATE THURS NGT. GIVEN FOCUS ON FIRST PERIOD OR TWO OF FORECAST AND TREND OF MODELS HAVING A SLOWER ARRIVAL TO ANY PRECIP HAVE KEPT THURS NGT UNTOUCHED WRT POPS AND DEFER TO OVERNIGHT SHIFT TO LOOK AT AGAIN. ANY ACCUMS TOWARDS FRI AM WOULD APPEAR TO BE ON THE LIGHT SIDE. LONG TERM... FRIDAY THROUGH WEDNESDAY...CHALLENGES THIS PACKAGE INCLUDE THE AMOUNT OF SNOW FRIDAY WITH A WEAK UPPER LEVEL SYSTEM AND THE TIMING AND TYPES OF PRECIPITATION NEXT WEEK IN AN UNSETTLED PATTERN. FOR THIS PACKAGE...FAVOR THE ECMWF A LITTLE MORE THAN THE GFS DUE TO RUN TO RUN CONSISTENCY OF THE ECMWF. THE 06Z AND 18Z GFS RUNS HAVE BEEN VERY INCONSISTENT WITH THE 12Z AND 00Z RUN. THE 12Z GFS RUN HAS TRENDED MUCH WARMER TUESDAY FROM THE 06Z RUN AND NOW SUPPORTS THE ECMWF. FOR FRIDAY...THE ONGOING TIMING AND AMOUNTS OF SNOW LOOK GOOD. THE GARCIA METHOD WITH MIXING RATIOS TOPPING 3 G/KG SUPPORT SNOW AMOUNTS OF GENERALLY 1 TO 3 INCHES GIVEN SOMEWHAT LIMITED ISENTROPIC LIFT...BUT FAVORABLE JET DYNAMICS AND AGEOSTROPHIC CIRCULATION. COLDER AIR WILL SPREAD BACK OVER THE REGION WITH MORE LAKE EFFECT SNOW EXPECTED FRIDAY NIGHT INTO SATURDAY. EXTENDED THE TIMING OF THE LAKE EFFECT SNOW A LITTLE MORE INTO SATURDAY GIVEN A FAVORABLE FETCH OVER THE LONG AXIS OF THE LAKE. FOR SUNDAY NIGHT INTO MONDAY...ADDED FREEZING RAIN AND SLEET GIVEN THERMAL PROFILES. UPDATED THE HAZARDOUS WEATHER OUTLOOK IN THIS REGARD FOR THE POTENTIAL FOR THIS WINTRY MIX WITH TRAVEL ISSUES POSSIBLE. TRENDED TUESDAY A LITTLE WARMER GIVEN WARM TEMPERATURES AT 850 MB AND GOOD MIXING EXPECTED. BELIEVE SNOW COVER SHOULD BE VERY LIMITED BY TUESDAY AFTERNOON AND SHOULD NOT BE AN ISSUE IN KEEP TEMPERATURES FROM CLIMBING WELL INTO THE 40S. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...LAKE EFFECT SNOW ADVISORY FROM 9 PM THIS EVENING TO 6 AM CST THURSDAY FOR INZ003. MI...LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST THURSDAY FOR MIZ077. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 11 AM EST THURSDAY FOR LMZ043-046. && $$ SHORT TERM...FISHER LONG TERM...SKIPPER UPDATE/AVIATION...T
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1240 AM EST TUE JAN 22 2013 .AVIATION... LAKE EFFECT CONTINUES WITH A DOMINANT BAND FOCUSED OVER KSBN. RADAR TRENDS SHOWS THIS BAND FAIRLY STATIONARY WITH RENEWED DEVELOPMENT UPSTREAM. KEPT VIS BELOW 1SM THROUGH THE NIGHT WITH OCCASIONAL 1/4SM AND HEAVY SNOW. THIS BAND MAY BEGIN TO SHIFT NORTH AFTER 12Z AS MEAN FLOW BACKS JUST A FEW DEGREES. STILL EXPECT CONTINUED SNOW SHOWERS WITH EXTREME INSTABILITY IN PLACE. VFR EXPECTED AT KFWA THOUGH MODELS SUGGEST SOUTHERN FRINGE OF LAKE CLOUDS MAY EXTEND INTO NORTHERN ALLEN COUNTY. && .UPDATE... MULTI BAND LK EFFECT CONTS UNABATED THIS EVENING IN RESPONSE TO EXTREME LK INDUCED INSTABILITY. PRIMARY LIMITING FCTR TO ACCUMS CONTS TO BE POOR MICROPHYSICAL THERMO ENVIRONMENT W/LL ASCENT MAXIMUM CNTRD ARND -20C. THUS XPC FINE POWDER SMALL PLATE CRYSTAL TYPE TO DOMINATE W/SUBSEQUENT ACCUMS SIGLY LIMITED. OTRWS HRRR/RUC MODEL FCST TRENDS DOVETAIL IN NICELY W/OBSVD RADAR/SAT TRENDS THIS EVENING W/GENERAL SLOW VEER AND SLOW SWD SUPPRESSION OF STRONGEST INLAND PENETRATING CONVERGENT BAND. XPC UPTICK IN BAND EVOLUTION OVERNIGHT W/BTR LK INDUCED SATURATION DVLPG WITHIN SHALLOW CLD GROWTH LYR. IN FACT BASED ON RUC CROSS-SECTIONS DEEPENING UVM MAY YIELD A PD OF LARGER SECTORED PLATE GROWTH TWD DAYBREAK TOMORROW. HWVR AS IT STANDS NOW WILL LEAVE ADVISORY AREA AS IS BUT CONCEDE SOME THREAT EXISTS SWD OF THE STATELINE ACRS ST. JOE...ELKHART AND LAGRANGE TO GET IN ON SOME DECENT SNOW ACCUMULATION LT TONIGHT THROUGH TUES. REGARDLESS PRIMARY OVERNIGHT GRID CHG SHIFTS HIGHEST POPS ABT 20 MILES SWD OF AFTN FCST. REMAINDER OF NR TERM GRIDS DEEMED ON TRACK AND LEFT UNCHGD. PROLONGED PD OF IFR/LIFR CONDS AT KSBN W/ORGANIZING SNOWBANDS OVERNIGHT...VFR AT KFWA. && .SHORT TERM...THROUGH TUESDAY NIGHT. LAKE EFFECT MACHINE HAS BEEN UNDERWAY ACROSS MUCH OF WESTERN LOWER MICHIGAN INTO PORTIONS OF NORTHERN INDIANA TODAY. ONE BAND SET UP FOR SEVERAL HOURS FROM BERRIEN INTO ST JOE COUNTIES IN MI BEFORE UNDULATING ACROSS THE AREA. DESPITE OCCASIONAL RETURNS UPWARDS OF 30 DBZ THAT WOULD SUGGEST 1 TO 2 INCH PER HOUR OR MORE SNOW RATES AMOUNTS THAT HAVE BEEN TRICKLING IN HAVE ONLY BEEN AN INCH OR LESS WITH SOME ISOLATED HIGHER AMOUNTS. ROADS HAVE BEEN REPORTED SNOW COVERED AND SLIPPERY ACROSS BERRIEN AND CASS COUNTIES WITH NO SIG IMPACTS ACROSS THE REMAINDER OF THE LAKE EFFECT ADVISORY AREA. HOWEVER...THE HEAVIER BANDS ARE STILL IMPACTING VSBYS...DOWN BELOW A HALF MILE AT TIMES...WITH BLOWING SNOW. RADAR TRENDS SUGGEST A LULL IN ACTIVITY MAY TRANSPIRE THIS EVENING AS WEAK SUBSIDENCE BEHIND THE DEPARTING WAVE KEEPS BANDS RATHER DISORGANIZED. GIVEN IMPACTS EXPECTED INTO THE EVENING AND LOWERING WIND CHILLS...WILL EXTEND LAKE EFFECT SNOW ADVISORY FOR WESTERN 3 MI COUNTIES THROUGH 5 AM BUT DROP BRANCH AND HILLSDALE. HI-RES MODELS INDICATE SNOW SHOWERS MAY PICK UP ONCE AGAIN LATER THIS EVENING INTO THE OVERNIGHT HOURS AND ESPECIALLY TUESDAY WITH ANOTHER SHOT OF MSTR AND INCREASED LIFT. SFC-850 MB DELTA T`S REMAIN MORE THAN FAVORABLE WELL INTO THE 20S BUT DGZ ONCE AGAIN WILL BE AT OR JUST ABOVE GROUND LEVEL...SETTING UP A SIMILAR SCENARIO TO TODAY WITH LACK OF DENDRITIC GROWTH AND RESULTANT LOW ACCUM POTENTIAL. SOME CHANGES MADE OVERNIGHT TO POPS TO ALIGN BETTER WITH CURRENT MODEL OUTPUT BUT NO SIG CHANGES MADE TO TUES/TUES NGT IN TERMS OF POPS/QPF/SNOWFALL. IN TERMS OF TEMPS AND WIND CHILLS...TEMPS TODAY HAVE FLUCTUATED BY SEVERAL DEGREES ACROSS THE AREA...WITH BRIEF RISES UNDER POCKETS OF SUNSHINE FOLLOWED BY A QUICK DROP BACK WITH CLOUD COVER ARRIVAL. UPSTREAM SIMILAR TRENDS ARE SEEN BUT MOST NOTABLE IS DECREASING DEWPTS...WELL INTO THE NEGATIVE TEENS. THESE SHOULD HEAD TOWARDS THE AREA TONIGHT. DESPITE LACK OF DECOUPLING TONIGHT OF WINDS...STRENGTH OF CAA WILL STILL ALLOW FOR A DROP OFF IN TEMPS INTO THE 0 TO 5 DEGREE ABOVE RANGE. WOULD NOT BE SURPRISED TO SEE A SPOT OR 2 GO SUB ZERO FOR A PERIOD. WIND CHILLS WILL STILL RANGE FROM -12 TO -18 IN MANY AREAS EVEN CLOSER TO THE LAKE. AS A RESULT WIND CHILL ADVISORY WILL CONTINUE WITH ONLY CHANGE BEING TO ADD BRANCH AND HILLSDALE COUNTIES. ONLY MODEST INCREASE IN TEMPS EXPECTED ON TUESDAY WITH HIGHS STRUGGLING INTO THE TEENS AND A QUICK DROP OFF BACK INTO THE SINGLE DIGITS TUES NGT. WIND CHILLS COULD HEAD TOWARDS CRITERIA ONCE AGAIN TUES NGT BUT WILL HOLD OFF ON ANY CHANGES/ADDITIONS TO THE CURRENT HEADLINES. && .LONG TERM.../WED-MON/ LONG WAVE TROF OVER ERN CANADA/U.S. WILL MAINTAIN NW FLOW ALOFT ACROSS THE GRTLKS AT START OF THIS PERIOD. ARCTIC AIRMASS WILL REMAIN IN PLACE WITH H85 TEMPS AROUND -20C WED MORNING. SHRTWV ROTATING AROUND CLOSED LOW OVER SE CANADA WILL DROP SE INTO THE WRN GRTLKS WED AND MAY PROVIDE SUFFICIENT FORCING TO CAUSE A FEW SNOW SHOWERS BEYOND JUST LAKE EFFECT AREAS. AS THE SHRTWV MOVES SE ACROSS THE GRTLKS WED NGT... WLY LOW LEVEL WINDS OVER SRN LM WILL VEER TO NE. IN THE PROCESS A BRIEF LONG NLY FETCH MAY ENHANCE LAKE EFFECT SNOW SHOWER ACTIVITY IN NW INDIANA... BUT PRBLY TOO SMALL A WINDOW TO RESULT IN SGFNT ACCUMS...ESPECIALLY CONSIDERING WARMING ALOFT AND LOWERING INVERSION OVERNIGHT. CLOSED LOW OVER NERN PAC EXPECTED TO KICK OUT A SHRTWV WHICH WILL BREAK DOWN WEST COAST RIDGE AND MOVE ACROSS PAC NW WED AND INTO THE PLAINS THU. CONSIDERABLE SPREAD IN LATEST MODELS ON TIMING/STRENGTH/TRACK OF THIS SYSTEM. ECMWF AND GFS OVER THE PAST 24HRS HAVE SLOWED EASTWARD MOVEMENT OF THE SHRTWV ACROSS THE COUNTRY AND AS SUCH HAVE LOWERED POPS FOR THU. UPR TROF SHOULD RESULT IN TWO SFC LOWS MOVG INTO THE PLAINS THU... WITH ONE MOVG SE FROM THE NRN PLAINS AND THE OTHER MOVG NE FROM THE SRN PLAINS THROUGH FRI. SRN LOW WILL HAVE MUCH MORE MOISTURE TO WORK WITH AND THUS GREATER POTENTIAL TO PRODUCE BAND OF SGFNT SNOW IN OR CLOSE TO OUR CWA. GIVEN RATHER LARGE MODEL DIFFERENCES ON TRACK OF SRN LOW... CONSIDERABLE UNCERTAINTY REMAINS AS TO WHERE THIS WILL BE... BUT APPEARS ATTM SRN PORTION OF OUR CWA OR POINTS FARTHER SOUTH HAVE GREATEST POTENTIAL. ANOTHER SURGE OF COLD AIR SHOULD FOLLOW THU NGT`S LOW INTO THE AREA WITH BLO NORMAL TEMPS AND SOME LES FRI-SAT. SFC HIGH PASSING TO THE EAST WITH MORE ZONAL FLOW ALOFT SHOULD RESULT IN A WARMING TREND SUNDAY-MONDAY. MEDIUM RANGE MODELS INDICATE A WK SHRTWV MAY MOVE THROUGH THE AREA IN THIS TIMEFRAME BUT GIVEN DISAGREEMENTS ON TIMING WITH SUCH A WK FEATURE... OPTED TO LEAVE PRECIP CHANCES OUT OF FCST FOR NOW. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL ADVISORY FROM 8 PM EST /7 PM CST/ THIS EVENING TO 11 AM EST /10 AM CST/ TUESDAY FOR INZ003>009-012>018-020- 022>027-032>034. MI...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 11 AM EST TUESDAY FOR MIZ080-081. LAKE EFFECT SNOW ADVISORY UNTIL 5 AM EST TUESDAY FOR MIZ077>079. OH...WIND CHILL ADVISORY FROM 8 PM THIS EVENING TO 11 AM EST TUESDAY FOR OHZ001-002-004-005-015-016-024-025. LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST WEDNESDAY FOR LMZ043-046. && $$ SHORT TERM...FISHER LONG TERM...JT UPDATE...T AVIATION...LASHLEY
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
940 PM CST WED JAN 23 2013 .UPDATE... FINAL BAND OF FLURRIES AND SNOW SHOWERS (ROUGHLY 30 MI WIDE) WITH LEADING EDGE FROM NEAR CLINTON TO STERLING WILL CONTINUE TO DIVE SOUTH NEXT FEW HRS EXITING CWA BY 07Z-08Z. THIS MAY BRING QUICK DUSTING OF ACCUM TO FEW LOCATIONS NEAR TO EAST OF MISSISSIPPI RVR. SKIES THEN CLEAR IN WAKE OF SYSTEM OVERNIGHT WITH JUST SOME HIGH THIN CLOUDS. AS FOR WIND CHILL ADVISORY FOR PORTIONS OF NORTHEAST IA AND NORTHWEST IL... IT WENT INTO EFFECT AT 8 PM BUT WE HAVE NOT BEEN CLOSE TO MEETING CRITERIA THUS FAR AS FCST TEMPS HAVE BEEN RUNNING COLDER THAN OBS. TO AVOID ANY CONFUSION I HAVE LEFT ADVISORY IN EFFECT HOWEVER I ADJUSTED WORDING IN ADVISORY TO HIGHLIGHT THE TIME PERIOD LATER TONIGHT THROUGH MID AM THU (08Z- 15Z) AS BEING THE MAIN WINDOW FOR THE DANGEROUSLY COLD WIND CHILLS OF AROUND 20 BELOW ZERO. AS FOR LOWS... TWEAKED UP 1-2 DEGS IN MOST PLACES WITH FCST RUNNING COLDER THAN OBS. LATEST RAP MODEL 2M TEMPS VERIFYING WELL WITH OBS AT 03Z AND SUPPORT LOWS AROUND ZERO TO 5 BELOW NORTH OF I-80 TO SINGLE DIGITS ABOVE ZERO TO THE SOUTH. GRIDS/ZFP HAVE BEEN SENT. && .PREV DISCUSSION... /ISSUED 656 PM CST WED JAN 23 2013/ UPDATE... BASED ON RADAR/SATL TRENDS AND OBS UPDATED FCST TO INCREASE CLOUD COVER AND MENTION ISOLD SNOW SHOWERS REST OF THE EVE FOR PORTIONS OF NORTHEAST IA AND NORTHWEST IL. PREV DISCUSSION... /ISSUED 610 PM CST WED JAN 23 2013/ AVIATION... LOW CLOUDS WITH SOME MVFR CIGS AND FLURRIES WILL AFFECT KDBQ TERMINAL NEXT FEW HRS BEFORE ERODING OR MOVING EAST WITH INCOMING SUBSIDENCE. OTHERWISE... VFR CONDITIONS TO PREVAIL THROUGH THU AFTN AS CANADIAN HIGH PRESSURE BUILDS IN. GUSTY NORTHWEST WINDS 10-20+ KTS TO GRADUALLY DIMINISH BELOW 10 KTS OVRNGT. ON THU... NORTHERLY WINDS 5-10 KTS TO BECOME E/SE BY MIDDAY THROUGH THU AFTN AS THE HIGH PRESSURE BEGINS TO PULL AWAY FROM REGION. PREV DISCUSSION... /ISSUED 258 PM CST WED JAN 23 2013/ SYNOPSIS... A COLD FRONT WAS PUSHING ACROSS EASTERN IA AT MID AFTERNOON WITH NORTHWEST WINDS GUSTING TO 25 TO 30 KNOTS BEHIND THE FRONT. STRONG COLD AIR ADVECTION WAS TAKING PLACE WITH THE PASSAGE OF THE FRONT AS TEMPERATURES HAVE FALLEN INTO THE TEENS IN NORTHERN IA AND SINGLE DIGITS IN SOUTHERN MN. EVEN COLDER FARTHER NORTH WITH READINGS BELOW ZERO ACROSS ND AND NORTHERN AND CENTRAL MN. CURRENTLY IN THE DVN CWA TEMPERATURES RANGED FROM ABOUT 20 FAR NORTH TO LOWER TO MID 30S FAR SOUTH. A NARROW BAND OF DENDRITIC SNOW THIS MORNING ACCUMULATED TO 0.5 TO 2.0 INCHES ROUGHLY ALONG HIGHWAY 20. THIS BAND OF SNOW OCCURRED ON THE CYCLONIC SIDE OF A NARROW 100 KNOT MID LEVEL WIND MAXIMUM WHERE VERTICAL MOTION WAS ENHANCED AND WAS CONCENTRATED IN A TIGHT BAROCLINIC ZONE. 850 MB TEMPERATURES AT 12Z WERE -20C AT KGRB AND +1C AT KOMA. SOUNDINGS INDICATED SATURATION OCCURRED IN THE FAVORED DENDRITIC GROWTH ZONE OF -12 TO -18C. SNOW/LIQUID RATIOS WERE AN INCREDIBLE 120:1 BASED ON OBSERVER MEASUREMENTS. HAASE SHORT TERM...TONIGHT AND THURSDAY... HEADLINES...HAVE ALREADY ISSUED A WIND CHILL ADVISORY FOR PORTIONS OF OUR NORTHERN CWA 8 PM THIS EVENING THROUGH 9 AM THURSDAY FOR WIND CHILLS OF 20 TO 25 BELOW ZERO. TONIGHT...FORECAST FOCUS ON TEMPERATURES AS COLD FRONT BRINGS COLDER WEATHER INTO THE REGION. FREQUENT WIND GUSTS TO 25 TO 30 WITH A FEW GUSTS POSSIBLY TO 35 MPH WILL OCCUR INTO THE EVENING HOURS. THESE WINDS WILL DIMINISH AFTER MIDNIGHT TO ABOUT 10 MPH AS 1044 MB HIGH PRESSURE BUILDS INTO THE REGION OUT OF CANADA. SKIES WILL CONTINUE TO CLEAR OVERNIGHT. OPERATIONAL MODELS HAVE LATCHED ONTO THE COLDER AIRMASS AND GUIDANCE IS NOW COLDER THAN PREVIOUS RUNS. IN ADDITION...THE FRESH SNOW THAT FELL IN OUR FAR NORTH THIS MORNING WILL HELP TO LOWER THE TEMPERATURE EVEN MORE. THEREFORE WILL FORECAST MINIMUM TEMPERATURES AS LOW AS 7 BELOW IN OUR FAR NORTH TO 5 ABOVE SOUTH. THIS WILL GIVE WIND CHILLS OF 15 TO 25 BELOW ZERO ALONG AND NORTH OF INTERSTATE 80. THURSDAY...FRIGID WIND CHILLS WILL CONTINUE THROUGH MID MORNING AND THEN IMPROVING CONDITIONS AS WINDS GO LESS THAN 10 MPH AS THE CENTER OF THE HIGH GETS CLOSER. IN THE AFTERNOON THE HIGH PRESSURE WILL PUSH INTO THE OHIO VALLEY. THIS WILL ALLOW LOW LEVEL WARM AIR ADVECTION TO KICK IN AND MID/HIGH LEVEL CLOUDS SHOULD INCREASE FROM WEST TO EAST. WILL BE A COLD DAY WITH MAXIMUM TEMPERATURES IN THE TEENS NORTH TO LOWER 20S SOUTH. WHERE THE FRESH SNOW FELL ACROSS PORTIONS OF HIGHWAY 20 THIS MORNING THOSE AREAS MAY STRUGGLE TO EVEN REACH THE TEENS ON THURSDAY. HAASE LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY... MODELS ARE CONSISTENT IN BRINGING A SHORT WAVE OUT OF THE NORTHERN PLAINS AND INTO THE WESTERN GREAT LAKES BY 12Z FRIDAY. MODEL QPF PROGS SHOW AN AREA OF LIGHT PRECIPITATION ASSOCIATED WITH THE SHORT WAVE FROM EASTERN IOWA INTO NORTHERN ILLINOIS LATE THURSDAY NIGHT. THE EXCEPTION TO THIS IS THE NAM SOLUTION WHICH KEEPS THE PRECIPITATION CLOSER TO THE S/W OVER MN AND WI. IT APPEARS THE NAMS LACK OF PCPN AWAY FROM THE S/W MAY BE DUE TO THE NAM HOLDING ON TO A LAYER OF NEAR SURFACE DRY AIR LONGER THAN THE OTHER OPERATIONAL MODELS. SINCE FORCING ON THE NAM LOOKS SIMILAR TO THE OTHER MODELS WILL STEER AWAY FROM IT/S DRIER SOLUTION AND LEAN TOWARD THE CONSENSUS. LIGHT SNOW IS EXPECTED TO SPREAD OVER THE AREA BEGINNING LATE THURSDAY EVENING AND CONTINUE OVERNIGHT. TIME HEIGHT PLOTS WERE SHOWING A BRIEF PERIOD...1 TO 2 HOURS...OF OPTIMAL LIFT IN THE DENDRITIC ZONE AFTER MIDNIGHT WHICH SHOULD PRODUCE MOST OF THE ACCUMULATIONS. WITH WATER EQUIVALENT AMOUNTS EXPECTED TO BE AROUND A TENTH OF AN INCH...ESPECIALLY OVER NORTHWEST ILLINOIS AND SNOW RATIOS IN THE 15 TO 20:1 RANGE...WE SHOULD SEE ACCUMULATIONS IN THE 1 TO 2 INCH RANGE ALONG AND EAST OF THE MISSISSIPPI RIVER BY 6 AM FRIDAY. THE SNOW SHOULD END QUICKLY FROM WEST TO EAST FRIDAY MORNING WITH ONLY SOME LINGERING FLURRIES POSSIBLE IN THE FAR EAST DURING THE AFTERNOON. AFTER MORNING LOWS IN THE TEENS FRIDAY...AFTERNOON SUN AND SOME MIXING SHOULD HELP TEMPERATURES REBOUND INTO THE 20S. HIGH PRESSURE MOVING INTO CENTRAL IOWA BY SATURDAY MORNING AND CLEAR SKIES SHOULD ALLOW GOOD RADIATIONAL COOLING. KEPT MINS IN THE SINGLE DIGITS OVER THE NORTHWEST HALF OF THE AREA SATURDAY MORNING AND AROUND 10 IN THE SOUTHEAST. THESE TEMPERATURES MAYBE ON THE WARM SIDE IF THE SNOWFALL PANS OUT THURSDAY NIGHT. SATURDAY WILL BE A TRANSITION DAY WITH THE WESTERN U.S. UPPER RIDGE MOVING EAST INTO THE CENTRAL U.S. AND A TROF DEVELOPING OVER THE WEST BY SATURDAY EVENING. LATE SATURDAY NIGHT A S/W EJECTS OUT OF THE WESTERN TROF AND MOVES THROUGH THE MID MISSISSIPPI VALLEY SUNDAY. THE MEDIUM RANGE MODELS ALL SHOW THIS SCENARIO BUT THERE ARE TIMING DIFFERENCES WITH THE ECMWF THE SLOWEST AND THE GFS ONE OF THE FASTER SOLUTIONS. DESPITE THE TIMING ISSUES...THE MODELS ALL SUGGEST A MIXED PRECIP EVENT SUNDAY AND SUNDAY NIGHT. THE PRECIP COULD BEGIN IN THE SOUTHWEST EARLY SUNDAY MORNING AND SPREAD NORTHEAST DURING THE DAY WITH THE PRECIP TYPE INCLUDING SNOW...FREEZING RAIN...SLEET AND RAIN. FOR MONDAY AND TUESDAY UNSETTLED WEATHER WILL STAY OVER THE AREA AS THE UPPER FLOW BECOMES SOUTHWESTERLY EARLY IN THE PERIOD CAUSING A WARM FRONT TO LIFT NORTH AND THEN STALL OVER OR JUST SOUTH OF THE FORECAST AREA. A WAVE IS THEN EXPECTED TO LIFT NORTHEAST ALONG THE BOUNDARY TUESDAY. THIS PATTERN SHOULD KEEP A MIX OF PRECIPITATION OVER THE AREA WITH MAINLY RAIN FAVORED IN THE SOUTH AND A MIX OF RAIN AND SNOW OVER THE NORTH MONDAY AND MONDAY NIGHT WITH MAINLY RAIN OVER THE ENTIRE AREA TUESDAY. THUNDERSTORMS OVER THE SOUTH AREN/T OUT OF THE QUESTION TUESDAY AS THE SURFACE LOW MOVES THROUGH OR NEAR THE FORECAST AREA. THE STALLED BOUNDARY WILL ALSO BRING MILD TEMPERATURES TO THE REGION WITH 30S AND 40S EXPECTED MONDAY AND 40S AND LOW 50S ON TUESDAY. COLDER AIR IS EXPECTED TO PUSH BACK INTO THE REGION TUESDAY NIGHT AND WEDNESDAY BEHIND THE DEPARTING SURFACE WAVE. DLF && .DVN WATCHES/WARNINGS/ADVISORIES... IA...WIND CHILL ADVISORY UNTIL 9 AM CST THURSDAY FOR BENTON-BUCHANAN- DELAWARE-DUBUQUE-JACKSON-JONES-LINN. IL...WIND CHILL ADVISORY UNTIL 9 AM CST THURSDAY FOR JO DAVIESS. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1144 AM CST TUE JAN 22 2013 .UPDATE... ADDED 18Z TAF DISCUSSION. MORNING UPDATE HAS LOWERED HIGHS SLIGHTLY AND LESSENED SNOW WORDING. FORECAST SOUNDINGS VS CURRENT OBS SUGGEST HIGHS NEEDED TO BE TRIMMED A BIT...MAINLY CENTRAL AND SW. CLOUDS SHOULD STAY IN PLACE AND COLD AIR SEEMS TO STILL BE ENTRENCHED WITH 15Z OBJECTIVE ANALYSIS STILL INDICATING WEAK PRESSURE RISES. WATER VAPOR IMAGERY AND LATEST RAP OUTPUT ALSO SUGGEST WEAK SHORT WAVE/PV ANOMALY JUST EXITING IA. VISIBLE IMAGERY ALSO SHOWS DEEPER TEXTURE ADVANCING INTO MO WHICH IS SUPPORTED BY REGIONAL RADAR MOSAIC SO HAVE REDUCED POPS AND ACCUMULATIONS. BETTER POTENTIAL MAY BE NORTH TONIGHT WHICH WILL BE RE-EVALUATED WITH AFTERNOON PACKAGE. REMNANTS OF WIND CHILL ADVISORY WILL BE ALLOWED TO EXPIRE AT 16Z. && .SHORT TERM /TODAY/... AREA OF SURFACE HIGH PRESSURE OVER THE AREA TO SLOWLY DRIFT EASTWARD AND SOUTHWARD TODAY...WITH CONTINUED NORTHWEST FLOW ALOFT. WEAK IMPULSES CONTINUE TO DROP SOUTHEASTWARD THROUGH THE STATE TODAY...ALONG WITH ZONE OF WAA/MOISTURE ADVECTION IN THE LOW/MID LEVELS MIGRATING OVER THE CWA THROUGH THE DAY SHOULD LEAD TO WEAK LIFT IN THE LOW/MID LEVELS THROUGHOUT THE DAY. ALSO DECENT ISENTROPIC LIFT SHOWING UP ACROSS EXTREME SOUTHWESTERN CWA THIS MORNING...AND PUSHING EAST/NORTHEASTWARD THIS AFTERNOON. AMOUNT OF MOISTURE BECOMES THE MAIN ISSUE...BUT SOUNDINGS SHOWING DECENT SATURATION ACROSS MUCH OF THE EASTERN CWA AT VARIOUS TIMES THROUGHOUT THE DAY. ALSO WITH COLD AIR IN PLACE BULK OF LIFT/SATURATION IN THE DENDRITIC LAYER. THEREFORE EVEN THOUGH MOISTURE IS LIMITED...SNOWFALL PRODUCTION WILL BE EFFICIENT THUS HAVE GONE WITH HIGHER POPS ACROSS THE SOUTHWEST THIS MORNING AND WEST/NORTHWEST THIS AFTERNOON. FEEL LIFT/MOISTURE AMOUNTS SHOULD BE ABLE TO SQUEEZE OUT A FEW TENTHS TO HALF AN INCH OR SO THROUGHOUT THE DAY. WAA WILL HELP TEMPS REBOUND SOME TODAY...BUT CLOUDS WILL INHIBIT THE WARMING SOME. THEREFORE STILL KEPT TEMPS ON THE COLD SIDE WITH HIGHS ONLY AROUND 10 ABOVE ACROSS THE NORTHEAST TO AROUND 20 SOUTH AND SOUTHWEST. BITTERLY COLD WIND CHILLS STILL EXPECTED THIS MORNING...SO HAVE CONTINUED THE WIND CHILL ADVISORY ACROSS THE NORTHEASTERN CWA THROUGH MID MORNING. .LONG TERM /TONIGHT THROUGH MONDAY/... WARM ADVECTION WILL INCREASE ACROSS THE STATE TONIGHT AS BAROCLINIC ZONE MOVES EAST ACROSS THE STATE. ISENTROPIC LIFT IS EXPECTED TO PERSIST THROUGH THE BOUNDARY WITH CLOUDS OVER MUCH OF CENTRAL IOWA DURING THE NIGHT. THE EXCEPTION WOULD BE IN THE SOUTHWEST WHERE LIFT SUBSIDES BY MIDNIGHT AS MAIN FORCING SHIFTS NORTHEAST. MODEL SOUNDINGS AT MASON CITY AND WATERLOO SHOW LOWEST 250MB OF SOUNDINGS CLOSE TO SATURATION IN THE DENDRITIC ZONE. ANTICIPATE SOME LIGHT SNOW OVERNIGHT ACROSS FAR NORTH CENTRAL INTO NORTHEAST CORNER OF THE FORECAST AREA AROUND WATERLOO. AMOUNTS WILL BE VERY LIGHT ALTHOUGH HIGH SNOW RATIOS MAY LEAD TO AN HALF OF INCH OF SNOW IN SOME LOCATIONS. THE STATE WILL SEE A BRIEF PERIOD OF WARMER TEMPERATURES INTO WEDNESDAY...HOWEVER A FRONT MOVING THROUGH DURING THE DAY WILL CURTAIL ANY WARMING ACROSS THE NORTH. READINGS FARTHER SOUTH WILL HAVE MORE TIME TO RISE AND MAY CLIMB ABOVE FREEZING BY EARLY AFTERNOON BEFORE COOLING ENSUES. GLANCING BLOW OF COOLER AIR INTO THURSDAY AS SURFACE RIDGE SLIDES INTO THE GREAT LAKES WITH WARM ADVECTION RE-INTENSIFYING BY THURSDAY AFTERNOON. NEXT SYSTEM WILL PASS THROUGH NORTHERN ROCKIES AND APPROACH THURSDAY NIGHT INTO FRIDAY. LIFT IS FORECAST TO INCREASE QUICKLY BY LATE THURSDAY AS MOISTURE BEGINS TO RETURN. LIGHT SNOW IS EXPECTED TO DEVELOP BY THURSDAY EVENING MAINLY ACROSS THE EASTERN HALF OF IOWA AS MOISTURE EVENTUALLY RETURNS. SOME LIGHT ACCUMULATIONS WILL BE POSSIBLE IN THE FAR EASTERN OF THE AREA BEFORE THE SYSTEM DEPARTS TO THE EAST ON FRIDAY MORNING. THERE WILL BE A BRIEF BREAK FROM LATE FRIDAY INTO SATURDAY EVENING AS HIGH PRESSURE PASSES THROUGH THE STATE. THE NEXT IN A SERIES OF SYSTEM IS FORECAST TO ARRIVE ON SUNDAY WITH THE THREAT OF RAIN OR SNOW AS THICKNESSES/TEMPERATURES CONTINUE TO INCREASE. && .AVIATION...22/18Z PERSISTENT BAND OF VFR CIGS FROM THE DAKOTAS INTO IA WILL CONTINUE TO DRIFT EASTWARD THROUGH THE PERIOD. LIGHT SNOW UPSTREAM IS EXPECTED TO MATURE BY EARLY EVENING AND BRUSH NRN IA 00-06Z...LIKELY AFFECTING KFOD/KMCW/KALO. CONDITIONS SHOULD DROP TO MVFR DURING THE LIGHT SNOW...AND POTENTIALLY LOWER...BUT CONFIDENCE IN THAT OCCURRENCE IS NOT GREAT ENOUGH TO INCLUDE AS OF YET. WINDS WILL BECOME NWLY AND INCREASE VERY LATE IN THE PERIOD AS WELL. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE/AVIATION...SMALL SHORT TERM...BEERENDS LONG TERM...COGIL
AREA FORECAST DISCUSSION
NWS DES MOINES IA
944 AM CST TUE JAN 22 2013 .UPDATE... MORNING UPDATE HAS LOWERED HIGHS SLIGHTLY AND LESSENED SNOW WORDING. FORECAST SOUNDINGS VS CURRENT OBS SUGGEST HIGHS NEEDED TO BE TRIMMED A BIT...MAINLY CENTRAL AND SW. CLOUDS SHOULD STAY IN PLACE AND COLD AIR SEEMS TO STILL BE ENTRENCHED WITH 15Z OBJECTIVE ANALYSIS STILL INDICATING WEAK PRESSURE RISES. WATER VAPOR IMAGERY AND LATEST RAP OUTPUT ALSO SUGGEST WEAK SHORT WAVE/PV ANOMALY JUST EXITING IA. VISIBLE IMAGERY ALSO SHOWS DEEPER TEXTURE ADVANCING INTO MO WHICH IS SUPPORTED BY REGIONAL RADAR MOSAIC SO HAVE REDUCED POPS AND ACCUMULATIONS. BETTER POTENTIAL MAY BE NORTH TONIGHT WHICH WILL BE RE-EVALUATED WITH AFTERNOON PACKAGE. REMNANTS OF WIND CHILL ADVISORY WILL BE ALLOWED TO EXPIRE AT 16Z. && .SHORT TERM /TODAY/... AREA OF SURFACE HIGH PRESSURE OVER THE AREA TO SLOWLY DRIFT EASTWARD AND SOUTHWARD TODAY...WITH CONTINUED NORTHWEST FLOW ALOFT. WEAK IMPULSES CONTINUE TO DROP SOUTHEASTWARD THROUGH THE STATE TODAY...ALONG WITH ZONE OF WAA/MOISTURE ADVECTION IN THE LOW/MID LEVELS MIGRATING OVER THE CWA THROUGH THE DAY SHOULD LEAD TO WEAK LIFT IN THE LOW/MID LEVELS THROUGHOUT THE DAY. ALSO DECENT ISENTROPIC LIFT SHOWING UP ACROSS EXTREME SOUTHWESTERN CWA THIS MORNING...AND PUSHING EAST/NORTHEASTWARD THIS AFTERNOON. AMOUNT OF MOISTURE BECOMES THE MAIN ISSUE...BUT SOUNDINGS SHOWING DECENT SATURATION ACROSS MUCH OF THE EASTERN CWA AT VARIOUS TIMES THROUGHOUT THE DAY. ALSO WITH COLD AIR IN PLACE BULK OF LIFT/SATURATION IN THE DENDRITIC LAYER. THEREFORE EVEN THOUGH MOISTURE IS LIMITED...SNOWFALL PRODUCTION WILL BE EFFICIENT THUS HAVE GONE WITH HIGHER POPS ACROSS THE SOUTHWEST THIS MORNING AND WEST/NORTHWEST THIS AFTERNOON. FEEL LIFT/MOISTURE AMOUNTS SHOULD BE ABLE TO SQUEEZE OUT A FEW TENTHS TO HALF AN INCH OR SO THROUGHOUT THE DAY. WAA WILL HELP TEMPS REBOUND SOME TODAY...BUT CLOUDS WILL INHIBIT THE WARMING SOME. THEREFORE STILL KEPT TEMPS ON THE COLD SIDE WITH HIGHS ONLY AROUND 10 ABOVE ACROSS THE NORTHEAST TO AROUND 20 SOUTH AND SOUTHWEST. BITTERLY COLD WIND CHILLS STILL EXPECTED THIS MORNING...SO HAVE CONTINUED THE WIND CHILL ADVISORY ACROSS THE NORTHEASTERN CWA THROUGH MID MORNING. .LONG TERM /TONIGHT THROUGH MONDAY/... WARM ADVECTION WILL INCREASE ACROSS THE STATE TONIGHT AS BAROCLINIC ZONE MOVES EAST ACROSS THE STATE. ISENTROPIC LIFT IS EXPECTED TO PERSIST THROUGH THE BOUNDARY WITH CLOUDS OVER MUCH OF CENTRAL IOWA DURING THE NIGHT. THE EXCEPTION WOULD BE IN THE SOUTHWEST WHERE LIFT SUBSIDES BY MIDNIGHT AS MAIN FORCING SHIFTS NORTHEAST. MODEL SOUNDINGS AT MASON CITY AND WATERLOO SHOW LOWEST 250MB OF SOUNDINGS CLOSE TO SATURATION IN THE DENDRITIC ZONE. ANTICIPATE SOME LIGHT SNOW OVERNIGHT ACROSS FAR NORTH CENTRAL INTO NORTHEAST CORNER OF THE FORECAST AREA AROUND WATERLOO. AMOUNTS WILL BE VERY LIGHT ALTHOUGH HIGH SNOW RATIOS MAY LEAD TO AN HALF OF INCH OF SNOW IN SOME LOCATIONS. THE STATE WILL SEE A BRIEF PERIOD OF WARMER TEMPERATURES INTO WEDNESDAY...HOWEVER A FRONT MOVING THROUGH DURING THE DAY WILL CURTAIL ANY WARMING ACROSS THE NORTH. READINGS FARTHER SOUTH WILL HAVE MORE TIME TO RISE AND MAY CLIMB ABOVE FREEZING BY EARLY AFTERNOON BEFORE COOLING ENSUES. GLANCING BLOW OF COOLER AIR INTO THURSDAY AS SURFACE RIDGE SLIDES INTO THE GREAT LAKES WITH WARM ADVECTION RE-INTENSIFYING BY THURSDAY AFTERNOON. NEXT SYSTEM WILL PASS THROUGH NORTHERN ROCKIES AND APPROACH THURSDAY NIGHT INTO FRIDAY. LIFT IS FORECAST TO INCREASE QUICKLY BY LATE THURSDAY AS MOISTURE BEGINS TO RETURN. LIGHT SNOW IS EXPECTED TO DEVELOP BY THURSDAY EVENING MAINLY ACROSS THE EASTERN HALF OF IOWA AS MOISTURE EVENTUALLY RETURNS. SOME LIGHT ACCUMULATIONS WILL BE POSSIBLE IN THE FAR EASTERN OF THE AREA BEFORE THE SYSTEM DEPARTS TO THE EAST ON FRIDAY MORNING. THERE WILL BE A BRIEF BREAK FROM LATE FRIDAY INTO SATURDAY EVENING AS HIGH PRESSURE PASSES THROUGH THE STATE. THE NEXT IN A SERIES OF SYSTEM IS FORECAST TO ARRIVE ON SUNDAY WITH THE THREAT OF RAIN OR SNOW AS THICKNESSES/TEMPERATURES CONTINUE TO INCREASE. && .AVIATION...22/12Z STILL EXPECTING MID/HIGH CLOUDS TO SLOWLY TRANSLATE EASTWARD THROUGH THE DAY...WITH SOME LOWER CLOUDS POSSIBLE ACROSS THE NORTHERN TAF SITES TOWARD THE LATTER PORTION OF THE TAF PERIOD. SOME LIGHT SNOW/FLURRIES ALSO POSSIBLE...WITH GREATEST CHANCES AT THE NORTHERN TAF SITES TOWARD LATE THIS AFTERNOON INTO TONIGHT. UNCERTAINTY IN HOW LOW CLOUD DECK WILL GET OR HOW MUCH VSBYS COULD BE REDUCED IN THE LIGHT SNOW...BUT AN OCCASIONAL DIP INTO MVFR VSBYS/CIGS IS POSSIBLE. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...SMALL SHORT TERM/AVIATION...BEERENDS LONG TERM...COGIL
AREA FORECAST DISCUSSION
NWS WICHITA KS
1147 PM CST MON JAN 21 2013 .AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU VFR CONDITIONS EXPECTED TO PREVAIL THRU THE FORECAST VALID PERIOD. LITTLE CHANGE TO THE PREVIOUS FORECAST...AS A DRY NORTHWEST FLOW REGIME ALOFT WILL CONTINUE AS A SHALLOW POLAR AIRMASS CONTINUES TO GRIP THE PLAINS. STRATUS AND STRATOCU CIGS WITHIN THE MORE FIRMLY ENTRENCHED COLD AIR IS EXPECTED TO REMAIN JUST NORTH AND EAST OF THE AREA...THOUGH A FEW LOWER CLOUDS AND A PERIOD OF ALTOCU WILL AFFECT PORTIONS OF CENTRAL AND EASTERN KANSAS OVERNIGHT. THE LIGHT EASTERLY COMPONENT SURFACE FLOW WILL VEER MORE SOUTHEASTERLY ON TUESDAY. KED && .PREV DISCUSSION... /ISSUED 546 PM CST MON JAN 21 2013/ AVIATION...00Z TAFS KRSL/KSLN/KHUT/KICT/KCNU VFR CONDITIONS EXPECTED TO PREVAIL THRU THE FORECAST VALID PERIOD. A DRY NORTHWEST FLOW REGIME ALOFT WILL CONTINUE AS A SHALLOW POLAR AIRMASS CONTINUES TO GRIP THE PLAINS. STRATOCU CIGS WITH THE MORE FIRMLY ENTRENCHED COLD AIR IS EXPECTED TO REMAIN JUST NORTH AND EAST OF THE AREA WITH THE SURFACE FLOW TAKING ON A GENERAL LIGHT EASTERLY COMPONENT. KED PREV DISCUSSION... /ISSUED 320 PM CST MON JAN 21 2013/ DISCUSSION... TODAY-WED: COMPLEX SURFACE PATTERN WITH REALLY COLD AIR SLOWLY BACKDOORING INTO FORECAST AREA...AND SOME RETURN FLOW DEVELOPING IN FAR WESTERN SECTIONS. NOT A LOT OF CONFIDENCE IN ANY OF THE MODELS ABILITY TO RESOLVE LOCATION OF COLDEST AIR AND RESULTANT LOW CLOUDS. BEST GUESS IS FOR COLD AIR TO CONTINUE TO SAG AT LEAST OVERNIGHT... POTENTIALLY LEAVING A SHARP BOUNDARY SOMEWHERE ACROSS THE AREA ON TUE. ANTICIPATE ANY LOW CLOUDS EARLY IN THE MORNING WILL BE ERODED FAIRLY QUICKLY AND WILL HAVE FAIR AMOUNT OF MODIFICATION OF COLD AIR NEAR BOUNDARY. BEST GUESS FOR WED IS LITTLE SURFACE FLOW... PROBABLY OUT OF THE EAST. THIS SHOULD RECIRCULATE COOL AIR...SO NOT EXPECTING MUCH RECOVERY AT THIS TIME. WED NIGHT-FRI: RETURN FLOW BEGINS TO DEVELOP ON BOTH ECMWF/GFS...WITH BOTH SHOWING 850MB MOISTURE WORKING NORTH...PRIMARY AFFECTING SOUTHERN SECTIONS DURING THE PERIOD. REMAINS TO BE SEEN WHETHER THERE WILL BE ENOUGH LIFT/MOISTURE TO OVERCOME DRY AIR NEAR SURFACE. BEST LIFT COMES THU AFTERNOON AND ESPECIALLY FRI MORNING. BEST CHANCE FOR PRECIPITATION THU WILL LIKELY BE IN SOUTHEAST KS IN THE AFTERNOON. BY FRI MORNING DRIER AIR WILL HAVE OVERSPREAD THE ENTIRE AREA. COLDER AIR SHOULD BE SPILLING INTO THE AREA ON FRI...WITH HIGH TEMPERATURES LOWER THAN ON THU. SAT-MON: GOOD AGREEMENT THAT LARGE SURFACE HIGH WILL DROP SOUTH ACROSS THE PLAINS ON SAT...WITH RETURN FLOW DEVELOPING ON SUN. HOWEVER SPREAD BETWEEN GFS/ECMWF STARTS TO INCREASE SIGNIFICANTLY DUE TO HANDLING OF SHORTWAVE MOVING THROUGH AND LONG WAVE TROUGH IN THE WESTERN US. BOTH APPEAR TO BE OVERLY AGRESSIVE WITH RETURN MOISTURE ON SUN AND MON AND HAVE OPTED TO KEEP FORECAST DRY FOR NOW. GIVEN SOUTHERN EXTENT OF SURFACE HIGH AND SURFACE TRAJECTORIES DURING THE PERIOD... SEEMS UNLIKELY TO GET SUFFICIENT MOISTURE THIS FAR NORTH THAT QUICK. SHOULD SEE TEMPERATURES REBOUND NICELY GIVEN RELATIVELY DRY AIR/DRY GROUND/SUNSHINE AND RETURN FLOW. -HOWERTON AVIATION...18Z TAFS KRSL/KSLN/KHUT/KICT/KCNU KRSL-KSLN-KCNU WILL BE FLIRTING WITH LOW VFR TO HIGH MVFR CIGS THIS AFTERNOON-EVENING...AND POSSIBLY THROUGH TONIGHT...AS SHALLOW COLD AIR TIED TO ARCTIC HIGH PRESSURE ENCROACHES FROM THE NORTHEAST. FOR NOW PLAYED THE CONSERVATIVE APPROACH...ALTHOUGH IF LATEST RUC BUFR SOUNDINGS VERIFY CIGS LESS THAN 2000 FT AGL COULD PREVAIL AS FAR SOUTH AS KHUT AND KICT BY MIDNIGHT. MODELS TEND TO NOT HANDLE SHALLOW COLD AIRMASSES VERY WELL...SO WILL CONTINUE TO MONITOR. ADK && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 18 45 26 52 / 0 0 0 0 HUTCHINSON 17 44 25 51 / 0 0 0 0 NEWTON 17 42 25 50 / 0 0 0 0 ELDORADO 16 41 25 52 / 0 0 0 0 WINFIELD-KWLD 19 46 27 57 / 0 0 0 0 RUSSELL 15 40 22 51 / 0 0 0 0 GREAT BEND 18 44 25 52 / 0 0 0 0 SALINA 15 38 22 49 / 0 0 0 0 MCPHERSON 16 42 24 50 / 0 0 0 0 COFFEYVILLE 17 44 27 58 / 0 0 10 10 CHANUTE 15 39 24 53 / 0 0 10 10 IOLA 15 37 24 51 / 0 0 0 0 PARSONS-KPPF 14 42 24 57 / 0 0 10 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CARIBOU ME
1239 PM EST TUE JAN 22 2013 .SYNOPSIS... FRIGID ARCTIC HIGH PRESSURE WILL BUILD IN FROM THE WEST THROUGH MID WEEK THEN CREST OVER THE REGION ON FRIDAY. LOW PRESSURE WILL PASS WELL SOUTH OF THE AREA ON SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... 1220 PM UPDATE...ADJUSTED THE SKY FORECAST TO ACCOUNT FOR MORE CLOUDS ADVANCING INTO OUR SWRN AREAS AND THAT SHIELD PUSHING NE ACROSS EAST-CENTRAL AREAS W/THAT LOW OFFSHORE. THE CANADIAN GEM WAS DOING WELL W/THIS SETUP AS WELL AS THE RUC WHICH WERE USED TO INITIALIZE AT 12 PM. MOST OF THE CLOUDS ACROSS THE NORTHERN 1/2 OF THE CWA WILL BE HIGH CLOUDINESS AND THIN. POPS NEEDED A FURTHER ADJUSTMENT S AND W BASED ON THE LATEST RADAR TRENDS AND OBS. LATEST VISIBLE SATL IMAGERY SHOWED A NICE EYE ON THE LOW OFFSHORE INDICATIVE OF THE INSTABILITY AROUND THE CENTER OF THE LOW. PREVIOUS DISCUSSION... THE LOW IS TRACKING JUST SOUTH OF THE GULF OF MAINE THIS MORNING AND WILL RAPIDLY MOVE NE TODAY PASSING JUST EAST OF GRAND BANK NEWFOUNDLAND THIS EVENING. A NORLUN TROUGH EXTENDS FROM THE LOW TO THE NH SEACOAST/SOUTHWEST MAINE COAST. THE HEAVIER SNOW (3 TO 6 INCHES) IS EXPECTED TO REMAIN SOUTH OF OUR CWA. THE POPS/QPF/SNOW AMOUNTS WERE INCREASED ACROSS THE SOUTHERN HALF OF HANCOCK COUNTY WITH UP TO 2 INCHES OF SNOW EXPECTED OVERNIGHT INTO THIS MORNING. ONCE THE LOW KICKS OUT THIS AFTERNOON THE FLOOD GATES OPEN FOR THE COLDEST AIR MASS OF THE WINTER TO SPILL INTO THE AREA TONIGHT AND WEDNESDAY. THE HEART OF THE COLDEST AIR MASS IS CURRENTLY BACK ACROSS NORTHERN ONTARIO WHERE SATELLITE INDICATES THAT THERE ARE LIKELY SFC TEMPS AS LOW AS -50F. THE UPPER LOW ASSOCIATED WITH THIS COLD BALL WILL MOVE EAST WITH THE TROUGH AXIS EXTENDING DOWN INTO NORTHERN NEW ENGLAND. BY 12Z WEDNESDAY 850 MB TEMPS OF -30C ARE EXPECTED ACROSS THE CROWN OF MAINE AND NOT MUCH WARMER ALONG THE COAST. THE CYCLONIC FLOW AROUND THE TROUGH WILL KEEP SOME CLOUD COVER AROUND AND PERHAPS EVEN A FEW WIDELY SCATTERED SNOW SHOWERS ACROSS NORTHERN AND WESTERN MAINE. AN INCREASING PRESSURE GRADIENT WILL PREVENT THE LOWER LEVELS FROM DECOUPLING. THE BIG CONCERN WILL BE FOR DANGEROUSLY COLD WIND CHILLS BEGINNING AROUND MIDNIGHT TONIGHT AND CONTINUING INTO THE SHORT TERM. A WIND CHILL WATCH WILL BE ISSUED FOR THE NORTHERN HALF OF THE CWA STARTING AT 06Z TONIGHT. ADVISORIES WILL LIKELY BE NEEDED TOWARD 12Z WEDNESDAY FOR INTERIOR DOWNEAST. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... THE CORE OF SOME BITTERLY COLD ARCTIC AIR WILL BE PRESSING INTO THE REGION ON WEDNESDAY. THE GRADIENT BETWEEN HIGH PRESSURE BUILDING IN FROM THE WEST AND LOWER PRESSURE IN EASTERN CANADA WILL BRING GUSTY WEST TO NORTHWEST WINDS WEDNESDAY INTO THURSDAY WITH THE FRIGID COLD LASTING INTO THURSDAY. WIND CHILLS ARE EXPECTED TO BE AS LOW AS 35 TO 40 BELOW ACROSS CENTRAL AND NORTHERN AREAS WHERE A WIND CHILL WATCH HAS BEEN ISSUED WEDNESDAY INTO THURSDAY. SOME MOISTURE BACKING AROUND THE EASTERN CANADIAN TROUGH WILL WORK ITS WAY INTO THE AREA LATE WEDNESDAY THROUGH WEDNESDAY NIGHT. THIS WILL BRING A THIN OVERCAST AND SOME VERY FINE POWDERY PATCHY LIGHT SNOW SHOWERS ESPECIALLY ACROSS THE FAR NORTH AND NORTHWEST. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... ARCTIC HIGH PRESSURE WILL BUILD OVER THE AREA ON FRIDAY BRINGING SUNSHINE AND LIGHTER WINDS BUT STILL VERY COLD TEMPS. LOW PRESSURE WILL TRACK OFF THE MID ATLANTIC COAST FRIDAY NIGHT. MODELS ARE IN DISAGREEMENT ABOUT THE TRACK OF THIS LOW. THE GFS SLIDES THE SYSTEM OUT TO SEA BRUSHING THE DOWNEAST COAST WITH SOME LIGHT SNOW. THE NEW ECMWF ALLOWS A NEW TROUGH DIGGING INTO THE GREAT LAKES REGION TO CAPTURE THE LOW AND CARRY IT NORTH BRINGING SIGNIFICANT SNOW TO OUR REGION. THIS IS A BIG CHANGE FROM PREVIOUS RUNS. FOR NOW WILL FORECAST A CHANCE OF SNOW FOR SATURDAY WITH BEST CHANCES DOWNEAST. COLD DRY WEATHER WILL FOLLOW FOR LATE IN THE WEEKEND INTO EARLY NEXT WEEK. && .AVIATION /17Z TUESDAY THROUGH SATURDAY/... NEAR TERM: VFR AT THE NORTHERN TERMINALS TODAY WITH A FEW BRIEF PERIODS OF MVFR TONIGHT IN ISO -SHSN. A BRIEF PERIOD OF MVFR POSSIBLE AT KBHB IN -SN THIS MORNING...BUT NOW LOOKING MORE LIKE IT WILL REMAIN VFR AS THE STEADIER SNOW REMAINS SOUTH OF THE TERMINAL. SHORT TERM: GENERALLY VFR CONDITIONS ARE EXPECTED WEDNESDAY THROUGH THURSDAY ALTHOUGH PATCHY LIGHT SNOW SHOWERS MAY BRIEFLY LOWER CONDITIONS TO MVFR ACROSS THE NORTH. VFR CONDITIONS ARE EXPECTED ON FRIDAY. VFR CONDITIONS ACROSS THE NORTH AND MVFR CONDITIONS IN LIGHT SNOW DOWNEAST ARE EXPECTED ON SATURDAY. && .MARINE... NEAR TERM: THE GLW WILL BE ABLE TO TRANSITION TO A SCA BY 19Z AS WIND GUSTS HAVE DROPPED BELOW 35 KTS. THE WINDS WILL GET CRANKING LATER TONIGHT AS THE STRONGER COLD AIR ADVECTION REACHES THE COAST. SHORT TERM: AN SCA IS EXPECTED WEDNESDAY THROUGH THURSDAY WITH SIGNIFICANT FREEZING SPRAY IN BITTER COLD CONDITIONS. WINDS SHOULD BE LIGHTER ON FRIDAY AS HIGH PRESSURE BUILDS OVER. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...WIND CHILL WARNING FROM 3 AM WEDNESDAY TO 1 PM EST THURSDAY FOR MEZ001>006-010. WIND CHILL ADVISORY FROM 3 AM TO 5 PM EST WEDNESDAY FOR MEZ011- 015>017-029>032. MARINE...GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR ANZ050>052. && $$ NEAR TERM...HEWITT
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1228 PM EST TUE JAN 22 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 431 AM EST TUE JAN 22 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW STEADY STATE HI AMPLITUDE PATTERN WITH DEEP TROF OVER ERN NAMERICA DOWNSTREAM OF RDG ALONG THE W COAST. CORE OF ARCTIC AIR AT 00Z WAS CENTERED IN NW ONTARIO OVER YPL...WHICH REPORTED LOWEST H85 TEMP ON THE MAP WITH -36C. INL/RB ALSO REPORTED NOTEWORTHY H85 TEMPS OF -30C/-31C AT 00Z. FARTHER NW OF THIS CORE OF COLDEST AIR...00Z H85 TEMPS AT THE PAS MANITOBA AND CHURCHILL MANITOBA WERE A MUCH MORE MODEST -23C. A FEW PLACES OVER INTERIOR UPR MI HAVE SEEN SFC TEMPS FALL AS LO AS -15 TO -20F...WITH LOWEST WIND CHILLS IN THE -30 TO -35F RANGE. WITH LINGERING CYC NW FLOW OVER THE UPR LKS UNDER THIS BITTERLY COLD AIR...LES CONTINUES MAINLY IN THE NW WIND SN BELTS. AS EXPECTED... WITH VERY COLD AIR ELIMINATING THE DGZ...SNOWFLAKE SIZE HAS BEEN VERY SMALL. THE SMALL FLAKES ARE VERY EFFECTIVE AT REDUCING VSBY... SO WHERE LES IS OCCURRING...WHITE-OUTS ARE COMMON. FOR THE MOST PART...SMALL FLAKES ARE LIMITING ACCUMS WITH MOST RECENT SPOTTER/ COOP REPORTS INDICATING MOSTLY 1-3IN/12HR SNOWFALL RATES. EXCEPTION IS OVER THE FAR NE FCST AREA...WHERE MORE LONGER FETCH/MORE LK MODERATION IS LIKELY ALLOWING THE DGZ INTO THE LOWEST LYRS AND SHARPER LLVL CNVGC ENHANCED BY LAND BREEZES IS PROVIDING EXTRA LLVL LIFT/FOCUS FOR SHSN. LOOKING JUST UPSTREAM TO THE NW...A WEAKER PRES GRADIENT IS APPARENT UPSTREAM OF LK SUP. TODAY...CWA WL REMAIN UNDER PERSISTENT NW FLOW ALF...BUT CORE OF COLDEST AIR NOW IN PLACE IS PROGGED TO SHIFT TO THE E AS THE LLVL FLOW BACKS...WITH H85 TEMPS FCST TO RISE TO WITHIN A FEW DEGREES OF -25C BY 00Z THIS EVNG. COMBINATION OF CORE OF COLDEST AIR SHIFTING TO THE E AND LIGHTER WINDS THAN YDAY WITH ARRIVAL OF WEAKER PRES GRADIENT SHOULD ALLOW SOME MODERATION IN THE WIND CHILLS. SO GOING ADVY EXPIRATION OF THOSE ADVYS AT 18Z LOOKS ON TRACK. HOWEVER...THE AIRMASS WL REMAIN MORE THAN SUFFICIENTLY COLD FOR PERSISTENT LES/LK CLDS DESPITE LARGER SCALE QVECTOR DVGC/SUBSIDENCE THAT IS FCST TO LOWER INVRN BASE TOWARD 5K FT AND LIMIT DEPTH OF MSTR. BUT FCST SDNGS STILL SHOW TEMPS WITHIN THE COLUMN WL REMAIN TOO LO FOR SN FLAKE GROWTH...SO EXPECT FINER FLAKES TO REMAIN THE RULE. HEAVIER LES WITH SOMEWHAT HIER TEMPS MODERATED BY LONGER FETCH OVER THE LK AND LINGERING SHARPER LLVL CNVGC WL REMAIN THE RULE IN AREAS E OF MUNISING. AS THE LARGER SCALE FLOW BACKS MORE WNW...EXPECT THE LES OVER THE ERN CWA TO BECOME MORE CONFINED TO AREAS NEAR LK SUP E OF MUNISING. OVER THE W...THE LES BANDS SHOULD SHIFT N OUT OF GOGEBIC COUNTY BUT STILL IMPACT AREAS FM ONTONAGON THRU THE KEWEENAW. TNGT...EXPECT A CONTINUED SLOW MODERATION AS LLVL WNW FLOW SHIFTS COLDEST H85 AIR TO THE E. BY 12Z...H85 TEMPS ARE PROGGED TO BE ARND -22C. LES SHOULD BE CONFINED TO MAINLY AREAS N OF ONTONAGON OVER THE W AND TO NEAR LK SUP E OF PICTURED ROCKS OVER THE ERN CWA. WITH SOME MODERATION IN THE CHILL...SN/WATER RATIOS WL LIKELY BECOME HIER WITH EMERGENCE OF THE DGZ IN THE LOWEST FEW THOUSAND FEET OF THE CONVECTIVE LYR. WITH THE MODERATING AIRMASS...MIN TEMPS WL NOT BE AS LO AS THIS MRNG AT MOST SPOTS EXCEPT OVER THE INTERIO WCNTRL WHERE LIGHTER WINDS AND AT LEAST SOME CLRG WL ALLOW MORE RADIATION COOLING. SINCE WINDS OVER THE COLDER INTERIOR SHOULD GENERALLY BE UNDER 10 MPH...SUSPECT WIND CHILLS FOR THE MOST PART WL REMAIN ABV ADVY CRITERIA. OPTED TO EXTEND LES WRNG FOR ALGER/LUCE COUNTIES AND WINTER WX ADVY FOR ONTONAGON COUNTY/THE KEWEENAW THRU TNGT TO ACCOUNT FOR EXPECTED TRENDS NOTED ABV. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 431 AM EST TUE JAN 22 2013 MODELS ARE IN GOOD AGREEMENT THROUGH ALL BUT SUN/MON...SO FORECAST CONFIDENCE IS HIGH THROUGH MOST OF THE LONG TERM. WED AND WED NIGHT...AN UPPER TROUGH WILL PUSH THROUGH THE CWA WED...HELPING FORM A MESO-LOW /AS INDICATED BY MAJORITY OF MODELS/ OVER FAR ERN LAKE SUPERIOR. WINDS WILL INITIALLY BE OUT OF THE WNW WED MORNING...BUT WILL TURN NLY BY 00Z THU AFTER THE TROUGH PASSES...THE MESO LOW DIMINISHES AND A SFC HIGH BEGINS PUSHING IN FROM THE NW. 850MB TEMPS WILL START THE DAY AROUND -22C AND END THE DAY AROUND -25C. EARLY IN THE DAY CONDITIONS WILL BE PRIME FOR MODERATE TO LOCALLY HEAVY LES...BUT BY TIME WINDS TURN NLY...DRY AIR AND LOWERING INVERSIONS WILL BEGIN TO LIMIT LES TO LIGHT TO MODERATE INTENSITY. BY 12Z THU...WINDS WILL BE LIGHT AND QUITE ANTICYCLONIC OVER LAKE SUPERIOR AS THE HIGH CENTER IS JUST NW OF THE LAKE. EXPECT DIMINISHING LES THROUGH WED NIGHT. HIGHEST SNOWFALL AMOUNTS FOR WED THROUGH WED NIGHT LOOK TO BE E OF MUNISING NEAR LAKE SUPERIOR WITH OVER 6 INCHES AND FROM ONTONAGON TO TWIN LAKES WITH OVER 5 INCHES. ELSEWHERE NEAR LAKE SUPERIOR...EXPECT 2-4 INCHES. THU...THE SFC HIGH WILL SHIFT E OF THE CWA THROUGH THE DAY...REACHING THE LOWER GREAT LAKES BY 00Z FRI. THIS PUTS THE REGION UNDER S-SE LOW LEVEL FLOW BEHIND THE HIGH AND AHEAD OF A TROUGH AND SFC LOW THAT WILL BE OVER THE DAKOTAS AT 00Z FRI. THU NIGHT AND FRI...SLY FLOW CONTINUES AS THE TROUGH/SFC LOW MOVES TO SE MN BY 12Z FRI...CAUSING 850MB TEMPS TO WARM TO THE MID TEENS BELOW ZERO. SHOULD SEE LAKE EFFECT/ENHANCED SNOW OFF LAKE MI AHEAD OF THE SYSTEM...HELPING TO BOOST SNOWFALL TOTALS IN SCHOOLCRAFT AND LUCE COUNTIES DEPENDING ON EXACT WIND DIRECTION. THE INVERTED TROUGH N OF THE SFC LOW WILL MOVE TO THE CENTRAL CWA AROUND 18Z FRI...THEN TO THE ERN CWA BY 00Z SAT. MODELS SHOW AROUND 0.2 INCHES OF SYNOPTIC QPF...AND NEARLY DOUBLE THAT DOWNWIND OF LAKE MICHIGAN. LOOKING AT MODEL PROFILES...THE BEST LIFT WILL BE ABOVE THE FAIRLY SHALLOW DGZ...SO SNOW TO LIQUID RATIOS WILL PROBABLY NOT BE THAT HIGH. AT THIS POINT IT LOOKS LIKE MOST LOCATIONS WILL SEE AROUND 3 INCHES OF SNOW WITH POSSIBLY 6 INCHES DOWNWIND OF LAKE MICHIGAN. A SHORTWAVE TROUGH LOOKS TO MOVE THROUGH LATE FRI INTO EARLY SAT NIGHT...WHICH SHOULD HELP GIVE A BRIEF BOOST TO LES IN THE NNW LOW LEVEL WINDS AND 850MB TEMPS AROUND -17C. ANY GOOD LES SHOULD NOT LAST LONG AS A SFC HIGH RIDGE MOVES TO WRN LAKE SUPERIOR AND 850MB TEMPS INCREASE TO AROUND -13C BY 18Z. LOW LEVEL FLOW ONCE AGAIN BECOMES SELY BEHIND THE RIDGE SAT NIGHT WITH 850MB TEMPS INCREASING TO A BALMY -5 OR SO BY 12Z SUN. FOR SUN AND MON...MODELS DO NOT HAVE GOOD AGREEMENT...BUT THEY SUGGEST THAT A SHORTWAVE MAY MOVE SOMEWHERE NEAR OR OVER THE AREA SUN OR SUN NIGHT. JUST USED A CONSENSUS OF MODELS FOR THIS PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1228 PM EST TUE JAN 22 2013 KIWD...AS THE LLVL FLOW BACKS MORE TO THE SW...EXPECT VFR CONDITIONS TO CONTINUE UNTIL A SHORTWAVE PASSES WED MORNING AND BRINGS BACK IN MVFR LAKE EFFECT SNOW SHOWERS. KCMX...EXPECT PREDOMINANT IFR CONDITIONS THRU THE DAY WITH UPSLOPE WNW FLOW OF ARCTIC AIR/LES. CONDITIONS SHOULD DETERIORATE TO LIFR TNGT AS AXIS OF SHARP CNVGC GETS SITUATED OVER THE KEWEENAW AND ENHANCES LES INTENSITY IN PERSISTENT UPSLOPE FLOW. KSAW...EXPECT PREDOMINANT VFR CONDITIONS THRU THIS FCST PERIOD WITH DOWNSLOPE WSW FLOW OF DRY AIR. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 431 AM EST TUE JAN 22 2013 EXPECT NW WINDS UP TO 20 TO 25 KTS THRU TONIGHT TO DRIVE ARCTIC AIR OVER THE UPPER GREAT LAKES. THERE WILL BE PERIODS OF HEAVY FREEZING SPRAY IN AREAS WHERE THE WINDS ARE STRONGEST. THE NW WINDS WILL STRENGTHEN TO 25 TO 30 KTS ON WED FOLLOWING THE PASSAGE OF A DISTRUBANCE...CAUSING MORE HEAVY FREEZING SPRAY THRU WED NIGHT. A WEAKER PRES GRADIENT/LIGHTER WINDS AND SOME MODERATION OF THE CHILL WILL END THE HEAVY FREEZING SPRAY BY THU. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR MIZ001>003- 084. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ085. WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ009. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST WEDNESDAY FOR MIZ006-007. WIND CHILL ADVISORY UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR MIZ004-005-010>014. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ THURSDAY FOR LSZ240>251-263>267. HEAVY FREEZING SPRAY WARNING UNTIL 1 AM EST /MIDNIGHT CST/ THURSDAY FOR LSZ162. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...TITUS AVIATION...07 MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
632 AM EST TUE JAN 22 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 431 AM EST TUE JAN 22 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW STEADY STATE HI AMPLITUDE PATTERN WITH DEEP TROF OVER ERN NAMERICA DOWNSTREAM OF RDG ALONG THE W COAST. CORE OF ARCTIC AIR AT 00Z WAS CENTERED IN NW ONTARIO OVER YPL...WHICH REPORTED LOWEST H85 TEMP ON THE MAP WITH -36C. INL/RB ALSO REPORTED NOTEWORTHY H85 TEMPS OF -30C/-31C AT 00Z. FARTHER NW OF THIS CORE OF COLDEST AIR...00Z H85 TEMPS AT THE PAS MANITOBA AND CHURCHILL MANITOBA WERE A MUCH MORE MODEST -23C. A FEW PLACES OVER INTERIOR UPR MI HAVE SEEN SFC TEMPS FALL AS LO AS -15 TO -20F...WITH LOWEST WIND CHILLS IN THE -30 TO -35F RANGE. WITH LINGERING CYC NW FLOW OVER THE UPR LKS UNDER THIS BITTERLY COLD AIR...LES CONTINUES MAINLY IN THE NW WIND SN BELTS. AS EXPECTED... WITH VERY COLD AIR ELIMINATING THE DGZ...SNOWFLAKE SIZE HAS BEEN VERY SMALL. THE SMALL FLAKES ARE VERY EFFECTIVE AT REDUCING VSBY... SO WHERE LES IS OCCURRING...WHITE-OUTS ARE COMMON. FOR THE MOST PART...SMALL FLAKES ARE LIMITING ACCUMS WITH MOST RECENT SPOTTER/ COOP REPORTS INDICATING MOSTLY 1-3IN/12HR SNOWFALL RATES. EXCEPTION IS OVER THE FAR NE FCST AREA...WHERE MORE LONGER FETCH/MORE LK MODERATION IS LIKELY ALLOWING THE DGZ INTO THE LOWEST LYRS AND SHARPER LLVL CNVGC ENHANCED BY LAND BREEZES IS PROVIDING EXTRA LLVL LIFT/FOCUS FOR SHSN. LOOKING JUST UPSTREAM TO THE NW...A WEAKER PRES GRADIENT IS APPARENT UPSTREAM OF LK SUP. TODAY...CWA WL REMAIN UNDER PERSISTENT NW FLOW ALF...BUT CORE OF COLDEST AIR NOW IN PLACE IS PROGGED TO SHIFT TO THE E AS THE LLVL FLOW BACKS...WITH H85 TEMPS FCST TO RISE TO WITHIN A FEW DEGREES OF -25C BY 00Z THIS EVNG. COMBINATION OF CORE OF COLDEST AIR SHIFTING TO THE E AND LIGHTER WINDS THAN YDAY WITH ARRIVAL OF WEAKER PRES GRADIENT SHOULD ALLOW SOME MODERATION IN THE WIND CHILLS. SO GOING ADVY EXPIRATION OF THOSE ADVYS AT 18Z LOOKS ON TRACK. HOWEVER...THE AIRMASS WL REMAIN MORE THAN SUFFICIENTLY COLD FOR PERSISTENT LES/LK CLDS DESPITE LARGER SCALE QVECTOR DVGC/SUBSIDENCE THAT IS FCST TO LOWER INVRN BASE TOWARD 5K FT AND LIMIT DEPTH OF MSTR. BUT FCST SDNGS STILL SHOW TEMPS WITHIN THE COLUMN WL REMAIN TOO LO FOR SN FLAKE GROWTH...SO EXPECT FINER FLAKES TO REMAIN THE RULE. HEAVIER LES WITH SOMEWHAT HIER TEMPS MODERATED BY LONGER FETCH OVER THE LK AND LINGERING SHARPER LLVL CNVGC WL REMAIN THE RULE IN AREAS E OF MUNISING. AS THE LARGER SCALE FLOW BACKS MORE WNW...EXPECT THE LES OVER THE ERN CWA TO BECOME MORE CONFINED TO AREAS NEAR LK SUP E OF MUNISING. OVER THE W...THE LES BANDS SHOULD SHIFT N OUT OF GOGEBIC COUNTY BUT STILL IMPACT AREAS FM ONTONAGON THRU THE KEWEENAW. TNGT...EXPECT A CONTINUED SLOW MODERATION AS LLVL WNW FLOW SHIFTS COLDEST H85 AIR TO THE E. BY 12Z...H85 TEMPS ARE PROGGED TO BE ARND -22C. LES SHOULD BE CONFINED TO MAINLY AREAS N OF ONTONAGON OVER THE W AND TO NEAR LK SUP E OF PICTURED ROCKS OVER THE ERN CWA. WITH SOME MODERATION IN THE CHILL...SN/WATER RATIOS WL LIKELY BECOME HIER WITH EMERGENCE OF THE DGZ IN THE LOWEST FEW THOUSAND FEET OF THE CONVECTIVE LYR. WITH THE MODERATING AIRMASS...MIN TEMPS WL NOT BE AS LO AS THIS MRNG AT MOST SPOTS EXCEPT OVER THE INTERIO WCNTRL WHERE LIGHTER WINDS AND AT LEAST SOME CLRG WL ALLOW MORE RADIATION COOLING. SINCE WINDS OVER THE COLDER INTERIOR SHOULD GENERALLY BE UNDER 10 MPH...SUSPECT WIND CHILLS FOR THE MOST PART WL REMAIN ABV ADVY CRITERIA. OPTED TO EXTEND LES WRNG FOR ALGER/LUCE COUNTIES AND WINTER WX ADVY FOR ONTONAGON COUNTY/THE KEWEENAW THRU TNGT TO ACCOUNT FOR EXPECTED TRENDS NOTED ABV. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 431 AM EST TUE JAN 22 2013 MODELS ARE IN GOOD AGREEMENT THROUGH ALL BUT SUN/MON...SO FORECAST CONFIDENCE IS HIGH THROUGH MOST OF THE LONG TERM. WED AND WED NIGHT...AN UPPER TROUGH WILL PUSH THROUGH THE CWA WED...HELPING FORM A MESO-LOW /AS INDICATED BY MAJORITY OF MODELS/ OVER FAR ERN LAKE SUPERIOR. WINDS WILL INITIALLY BE OUT OF THE WNW WED MORNING...BUT WILL TURN NLY BY 00Z THU AFTER THE TROUGH PASSES...THE MESO LOW DIMINISHES AND A SFC HIGH BEGINS PUSHING IN FROM THE NW. 850MB TEMPS WILL START THE DAY AROUND -22C AND END THE DAY AROUND -25C. EARLY IN THE DAY CONDITIONS WILL BE PRIME FOR MODERATE TO LOCALLY HEAVY LES...BUT BY TIME WINDS TURN NLY...DRY AIR AND LOWERING INVERSIONS WILL BEGIN TO LIMIT LES TO LIGHT TO MODERATE INTENSITY. BY 12Z THU...WINDS WILL BE LIGHT AND QUITE ANTICYCLONIC OVER LAKE SUPERIOR AS THE HIGH CENTER IS JUST NW OF THE LAKE. EXPECT DIMINISHING LES THROUGH WED NIGHT. HIGHEST SNOWFALL AMOUNTS FOR WED THROUGH WED NIGHT LOOK TO BE E OF MUNISING NEAR LAKE SUPERIOR WITH OVER 6 INCHES AND FROM ONTONAGON TO TWIN LAKES WITH OVER 5 INCHES. ELSEWHERE NEAR LAKE SUPERIOR...EXPECT 2-4 INCHES. THU...THE SFC HIGH WILL SHIFT E OF THE CWA THROUGH THE DAY...REACHING THE LOWER GREAT LAKES BY 00Z FRI. THIS PUTS THE REGION UNDER S-SE LOW LEVEL FLOW BEHIND THE HIGH AND AHEAD OF A TROUGH AND SFC LOW THAT WILL BE OVER THE DAKOTAS AT 00Z FRI. THU NIGHT AND FRI...SLY FLOW CONTINUES AS THE TROUGH/SFC LOW MOVES TO SE MN BY 12Z FRI...CAUSING 850MB TEMPS TO WARM TO THE MID TEENS BELOW ZERO. SHOULD SEE LAKE EFFECT/ENHANCED SNOW OFF LAKE MI AHEAD OF THE SYSTEM...HELPING TO BOOST SNOWFALL TOTALS IN SCHOOLCRAFT AND LUCE COUNTIES DEPENDING ON EXACT WIND DIRECTION. THE INVERTED TROUGH N OF THE SFC LOW WILL MOVE TO THE CENTRAL CWA AROUND 18Z FRI...THEN TO THE ERN CWA BY 00Z SAT. MODELS SHOW AROUND 0.2 INCHES OF SYNOPTIC QPF...AND NEARLY DOUBLE THAT DOWNWIND OF LAKE MICHIGAN. LOOKING AT MODEL PROFILES...THE BEST LIFT WILL BE ABOVE THE FAIRLY SHALLOW DGZ...SO SNOW TO LIQUID RATIOS WILL PROBABLY NOT BE THAT HIGH. AT THIS POINT IT LOOKS LIKE MOST LOCATIONS WILL SEE AROUND 3 INCHES OF SNOW WITH POSSIBLY 6 INCHES DOWNWIND OF LAKE MICHIGAN. A SHORTWAVE TROUGH LOOKS TO MOVE THROUGH LATE FRI INTO EARLY SAT NIGHT...WHICH SHOULD HELP GIVE A BRIEF BOOST TO LES IN THE NNW LOW LEVEL WINDS AND 850MB TEMPS AROUND -17C. ANY GOOD LES SHOULD NOT LAST LONG AS A SFC HIGH RIDGE MOVES TO WRN LAKE SUPERIOR AND 850MB TEMPS INCREASE TO AROUND -13C BY 18Z. LOW LEVEL FLOW ONCE AGAIN BECOMES SELY BEHIND THE RIDGE SAT NIGHT WITH 850MB TEMPS INCREASING TO A BALMY -5 OR SO BY 12Z SUN. FOR SUN AND MON...MODELS DO NOT HAVE GOOD AGREEMENT...BUT THEY SUGGEST THAT A SHORTWAVE MAY MOVE SOMEWHERE NEAR OR OVER THE AREA SUN OR SUN NIGHT. JUST USED A CONSENSUS OF MODELS FOR THIS PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 630 AM EST TUE JAN 22 2013 KIWD...AS THE LLVL FLOW BACKS MORE TO THE WSW...EXPECT LINGERING LES TO SHIFT TO THE N OF THIS LOCATION. SO MVFR/OCNL IFR CONDITIONS THIS MRNG SHOULD GIVE WAY TO VFR CIGS DURING THE AFTN AND TNGT. KCMX...EXPECT PREDOMINANT IFR CONDITIONS THRU THE DAY WITH UPSLOPE WNW FLOW OF ARCTIC AIR/LES. CONDITIONS SHOULD DETERIORATE TO LIFR TNGT AS AXIS OF SHARP CNVGC GETS SITUATED OVER THE KEWEENAW AND ENHANCES LES INTENSITY IN PERSISTENT UPSLOPE FLOW. KSAW...EXPECT PREDOMINANT VFR CONDITIONS THRU THIS FCST PERIOD WITH DOWNSLOPE WSW FLOW OF DRY AIR. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 431 AM EST TUE JAN 22 2013 EXPECT NW WINDS UP TO 20 TO 25 KTS THRU TONIGHT TO DRIVE ARCTIC AIR OVER THE UPPER GREAT LAKES. THERE WILL BE PERIODS OF HEAVY FREEZING SPRAY IN AREAS WHERE THE WINDS ARE STRONGEST. THE NW WINDS WILL STRENGTHEN TO 25 TO 30 KTS ON WED FOLLOWING THE PASSAGE OF A DISTRUBANCE...CAUSING MORE HEAVY FREEZING SPRAY THRU WED NIGHT. A WEAKER PRES GRADIENT/LIGHTER WINDS AND SOME MODERATION OF THE CHILL WILL END THE HEAVY FREEZING SPRAY BY THU. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR MIZ001>003- 084. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ085. WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ009. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST WEDNESDAY FOR MIZ006-007. WIND CHILL ADVISORY UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR MIZ004-005-010>014. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ THURSDAY FOR LSZ240>251-263>267. HEAVY FREEZING SPRAY WARNING UNTIL 1 AM EST /MIDNIGHT CST/ THURSDAY FOR LSZ162. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...TITUS AVIATION...KC MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
434 AM EST TUE JAN 22 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 431 AM EST TUE JAN 22 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW STEADY STATE HI AMPLITUDE PATTERN WITH DEEP TROF OVER ERN NAMERICA DOWNSTREAM OF RDG ALONG THE W COAST. CORE OF ARCTIC AIR AT 00Z WAS CENTERED IN NW ONTARIO OVER YPL...WHICH REPORTED LOWEST H85 TEMP ON THE MAP WITH -36C. INL/RB ALSO REPORTED NOTEWORTHY H85 TEMPS OF -30C/-31C AT 00Z. FARTHER NW OF THIS CORE OF COLDEST AIR...00Z H85 TEMPS AT THE PAS MANITOBA AND CHURCHILL MANITOBA WERE A MUCH MORE MODEST -23C. A FEW PLACES OVER INTERIOR UPR MI HAVE SEEN SFC TEMPS FALL AS LO AS -15 TO -20F...WITH LOWEST WIND CHILLS IN THE -30 TO -35F RANGE. WITH LINGERING CYC NW FLOW OVER THE UPR LKS UNDER THIS BITTERLY COLD AIR...LES CONTINUES MAINLY IN THE NW WIND SN BELTS. AS EXPECTED... WITH VERY COLD AIR ELIMINATING THE DGZ...SNOWFLAKE SIZE HAS BEEN VERY SMALL. THE SMALL FLAKES ARE VERY EFFECTIVE AT REDUCING VSBY... SO WHERE LES IS OCCURRING...WHITE-OUTS ARE COMMON. FOR THE MOST PART...SMALL FLAKES ARE LIMITING ACCUMS WITH MOST RECENT SPOTTER/ COOP REPORTS INDICATING MOSTLY 1-3IN/12HR SNOWFALL RATES. EXCEPTION IS OVER THE FAR NE FCST AREA...WHERE MORE LONGER FETCH/MORE LK MODERATION IS LIKELY ALLOWING THE DGZ INTO THE LOWEST LYRS AND SHARPER LLVL CNVGC ENHANCED BY LAND BREEZES IS PROVIDING EXTRA LLVL LIFT/FOCUS FOR SHSN. LOOKING JUST UPSTREAM TO THE NW...A WEAKER PRES GRADIENT IS APPARENT UPSTREAM OF LK SUP. TODAY...CWA WL REMAIN UNDER PERSISTENT NW FLOW ALF...BUT CORE OF COLDEST AIR NOW IN PLACE IS PROGGED TO SHIFT TO THE E AS THE LLVL FLOW BACKS...WITH H85 TEMPS FCST TO RISE TO WITHIN A FEW DEGREES OF -25C BY 00Z THIS EVNG. COMBINATION OF CORE OF COLDEST AIR SHIFTING TO THE E AND LIGHTER WINDS THAN YDAY WITH ARRIVAL OF WEAKER PRES GRADIENT SHOULD ALLOW SOME MODERATION IN THE WIND CHILLS. SO GOING ADVY EXPIRATION OF THOSE ADVYS AT 18Z LOOKS ON TRACK. HOWEVER...THE AIRMASS WL REMAIN MORE THAN SUFFICIENTLY COLD FOR PERSISTENT LES/LK CLDS DESPITE LARGER SCALE QVECTOR DVGC/SUBSIDENCE THAT IS FCST TO LOWER INVRN BASE TOWARD 5K FT AND LIMIT DEPTH OF MSTR. BUT FCST SDNGS STILL SHOW TEMPS WITHIN THE COLUMN WL REMAIN TOO LO FOR SN FLAKE GROWTH...SO EXPECT FINER FLAKES TO REMAIN THE RULE. HEAVIER LES WITH SOMEWHAT HIER TEMPS MODERATED BY LONGER FETCH OVER THE LK AND LINGERING SHARPER LLVL CNVGC WL REMAIN THE RULE IN AREAS E OF MUNISING. AS THE LARGER SCALE FLOW BACKS MORE WNW...EXPECT THE LES OVER THE ERN CWA TO BECOME MORE CONFINED TO AREAS NEAR LK SUP E OF MUNISING. OVER THE W...THE LES BANDS SHOULD SHIFT N OUT OF GOGEBIC COUNTY BUT STILL IMPACT AREAS FM ONTONAGON THRU THE KEWEENAW. TNGT...EXPECT A CONTINUED SLOW MODERATION AS LLVL WNW FLOW SHIFTS COLDEST H85 AIR TO THE E. BY 12Z...H85 TEMPS ARE PROGGED TO BE ARND -22C. LES SHOULD BE CONFINED TO MAINLY AREAS N OF ONTONAGON OVER THE W AND TO NEAR LK SUP E OF PICTURED ROCKS OVER THE ERN CWA. WITH SOME MODERATION IN THE CHILL...SN/WATER RATIOS WL LIKELY BECOME HIER WITH EMERGENCE OF THE DGZ IN THE LOWEST FEW THOUSAND FEET OF THE CONVECTIVE LYR. WITH THE MODERATING AIRMASS...MIN TEMPS WL NOT BE AS LO AS THIS MRNG AT MOST SPOTS EXCEPT OVER THE INTERIO WCNTRL WHERE LIGHTER WINDS AND AT LEAST SOME CLRG WL ALLOW MORE RADIATION COOLING. SINCE WINDS OVER THE COLDER INTERIOR SHOULD GENERALLY BE UNDER 10 MPH...SUSPECT WIND CHILLS FOR THE MOST PART WL REMAIN ABV ADVY CRITERIA. OPTED TO EXTEND LES WRNG FOR ALGER/LUCE COUNTIES AND WINTER WX ADVY FOR ONTONAGON COUNTY/THE KEWEENAW THRU TNGT TO ACCOUNT FOR EXPECTED TRENDS NOTED ABV. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 431 AM EST TUE JAN 22 2013 MODELS ARE IN GOOD AGREEMENT THROUGH ALL BUT SUN/MON...SO FORECAST CONFIDENCE IS HIGH THROUGH MOST OF THE LONG TERM. WED AND WED NIGHT...AN UPPER TROUGH WILL PUSH THROUGH THE CWA WED...HELPING FORM A MESO-LOW /AS INDICATED BY MAJORITY OF MODELS/ OVER FAR ERN LAKE SUPERIOR. WINDS WILL INITIALLY BE OUT OF THE WNW WED MORNING...BUT WILL TURN NLY BY 00Z THU AFTER THE TROUGH PASSES...THE MESO LOW DIMINISHES AND A SFC HIGH BEGINS PUSHING IN FROM THE NW. 850MB TEMPS WILL START THE DAY AROUND -22C AND END THE DAY AROUND -25C. EARLY IN THE DAY CONDITIONS WILL BE PRIME FOR MODERATE TO LOCALLY HEAVY LES...BUT BY TIME WINDS TURN NLY...DRY AIR AND LOWERING INVERSIONS WILL BEGIN TO LIMIT LES TO LIGHT TO MODERATE INTENSITY. BY 12Z THU...WINDS WILL BE LIGHT AND QUITE ANTICYCLONIC OVER LAKE SUPERIOR AS THE HIGH CENTER IS JUST NW OF THE LAKE. EXPECT DIMINISHING LES THROUGH WED NIGHT. HIGHEST SNOWFALL AMOUNTS FOR WED THROUGH WED NIGHT LOOK TO BE E OF MUNISING NEAR LAKE SUPERIOR WITH OVER 6 INCHES AND FROM ONTONAGON TO TWIN LAKES WITH OVER 5 INCHES. ELSEWHERE NEAR LAKE SUPERIOR...EXPECT 2-4 INCHES. THU...THE SFC HIGH WILL SHIFT E OF THE CWA THROUGH THE DAY...REACHING THE LOWER GREAT LAKES BY 00Z FRI. THIS PUTS THE REGION UNDER S-SE LOW LEVEL FLOW BEHIND THE HIGH AND AHEAD OF A TROUGH AND SFC LOW THAT WILL BE OVER THE DAKOTAS AT 00Z FRI. THU NIGHT AND FRI...SLY FLOW CONTINUES AS THE TROUGH/SFC LOW MOVES TO SE MN BY 12Z FRI...CAUSING 850MB TEMPS TO WARM TO THE MID TEENS BELOW ZERO. SHOULD SEE LAKE EFFECT/ENHANCED SNOW OFF LAKE MI AHEAD OF THE SYSTEM...HELPING TO BOOST SNOWFALL TOTALS IN SCHOOLCRAFT AND LUCE COUNTIES DEPENDING ON EXACT WIND DIRECTION. THE INVERTED TROUGH N OF THE SFC LOW WILL MOVE TO THE CENTRAL CWA AROUND 18Z FRI...THEN TO THE ERN CWA BY 00Z SAT. MODELS SHOW AROUND 0.2 INCHES OF SYNOPTIC QPF...AND NEARLY DOUBLE THAT DOWNWIND OF LAKE MICHIGAN. LOOKING AT MODEL PROFILES...THE BEST LIFT WILL BE ABOVE THE FAIRLY SHALLOW DGZ...SO SNOW TO LIQUID RATIOS WILL PROBABLY NOT BE THAT HIGH. AT THIS POINT IT LOOKS LIKE MOST LOCATIONS WILL SEE AROUND 3 INCHES OF SNOW WITH POSSIBLY 6 INCHES DOWNWIND OF LAKE MICHIGAN. A SHORTWAVE TROUGH LOOKS TO MOVE THROUGH LATE FRI INTO EARLY SAT NIGHT...WHICH SHOULD HELP GIVE A BRIEF BOOST TO LES IN THE NNW LOW LEVEL WINDS AND 850MB TEMPS AROUND -17C. ANY GOOD LES SHOULD NOT LAST LONG AS A SFC HIGH RIDGE MOVES TO WRN LAKE SUPERIOR AND 850MB TEMPS INCREASE TO AROUND -13C BY 18Z. LOW LEVEL FLOW ONCE AGAIN BECOMES SELY BEHIND THE RIDGE SAT NIGHT WITH 850MB TEMPS INCREASING TO A BALMY -5 OR SO BY 12Z SUN. FOR SUN AND MON...MODELS DO NOT HAVE GOOD AGREEMENT...BUT THEY SUGGEST THAT A SHORTWAVE MAY MOVE SOMEWHERE NEAR OR OVER THE AREA SUN OR SUN NIGHT. JUST USED A CONSENSUS OF MODELS FOR THIS PERIOD. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING) ISSUED AT 630 PM EST MON JAN 21 2013 LAKE EFFECT SNOW SHOWERS WILL CONTINUE OVER MAINLY THE IWD AND CMX TAF SITES THROUGH TUESDAY AFTERNOON. VISIBILITY WILL BE REDUCED TO 1/4 MILE AT TIMES AS THE HEAVIER SNOWBANDS MOVE THROUGH. IWD WILL LIKELY SEE A BRIEF BREAK IN THE SNOW SHOWERS EARLY THIS EVENING BEFORE THE NEXT AREA OF SNOW SHOWERS BUILDS SOUTHWARD INTO THE SITE. WINDS WILL ALSO BE GUSTING TO 20 KTS OR BETTER ALLOWING FOR INCREASED BLSN POTENTIAL...ALSO HELPING TO REDUCE VSBY. CEILINGS ARE EXPECTED TO REMAIN AROUND 1500 TO 2000 FT AT CMX AND IWD. KSAW WILL REMAIN AT MVFR THROUGH TUESDAY MORNING AS INCREASED MOISTURE MOVES INTO THE TAF SITE. DOWNSLOPING WESTERLY WINDS WILL HELP TO ERODE THE CLOUD COVER THROUGH THE LATE MORNING AND EARLY AFTERNOON HOURS...POSSIBLY SCATTERING OUT BY 19Z. VSBY SHOULD REMAIN VFR THROUGH THE TAF PERIOD WITH ONLY MINOR REDUCTION IN VSBY THIS EVENING WITH GUSTY WINDS CREATING BLSN. WEST TO NORTHWEST WINDS ARE NOT A FAVORED LAKE EFFECT DIRECTION FOR KSAW...THEREFORE HAVE KEPT -SHSN OUT OF THE TAF ALTHOUGH A FEW SNOW SHOWERS ARE STILL POSSIBLE. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 431 AM EST TUE JAN 22 2013 EXPECT NW WINDS UP TO 20 TO 25 KTS THRU TONIGHT TO DRIVE ARCTIC AIR OVER THE UPPER GREAT LAKES. THERE WILL BE PERIODS OF HEAVY FREEZING SPRAY IN AREAS WHERE THE WINDS ARE STRONGEST. THE NW WINDS WILL STRENGTHEN TO 25 TO 30 KTS ON WED FOLLOWING THE PASSAGE OF A DISTRUBANCE...CAUSING MORE HEAVY FREEZING SPRAY THRU WED NIGHT. A WEAKER PRES GRADIENT/LIGHTER WINDS AND SOME MODERATION OF THE CHILL WILL END THE HEAVY FREEZING SPRAY BY THU. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR MIZ001>003- 084. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ085. WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ009. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST WEDNESDAY FOR MIZ006-007. WIND CHILL ADVISORY UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR MIZ004-005-010>014. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ THURSDAY FOR LSZ240>251-263>267. HEAVY FREEZING SPRAY WARNING UNTIL 1 AM EST /MIDNIGHT CST/ THURSDAY FOR LSZ162. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...TITUS AVIATION...KEC MARINE...KC
AREA FORECAST DISCUSSION...CORRECTED
NWS HASTINGS NE
1206 AM CST TUE JAN 22 2013 .AVIATION.../06Z GRI TAF THROUGH 06Z TUESDAY NIGHT/ THRU 12Z: MVFR CIGS SEEM TO BE EXPANDING WHICH INCREASES CONFIDENCE THAT MVFR CIGS WILL PREVAIL...BUT CONFIDENCE IS ONLY AVERAGE BECAUSE THE EDGE IS BETWEEN ODX AND GRI. LIGHT SE WINDS 5 KTS OR LESS. UNRESTRICTED VSBYS. TUE: MVFR OR LOW-END VFR OVC THRU 20Z...BUT AS TEMPS INCREASE CLEARING WILL MOVE THRU AFTER 21Z. SE WINDS AT OR BELOW 10 KTS. UNRESTRICTED VSBYS. TUE EVE: ESSENTIALLY VFR SKC. SE WINDS AROUND 5 KTS. CIG CONFIDENCE: AVERAGE THRU 21Z THEN HIGH VSBY CONFIDENCE: HIGH WIND CONFIDENCE: HIGH WX CONFIDENCE: HIGH && .PREV DISCUSSION... /ISSUED 957 PM CST MON JAN 21 2013/ UPDATE...THE RUC CONTINUES TO GENERATE LIGHT SNOW ACROSS OUR NORTHEAST ZONES THIS EVENING...WHICH THUS FAR HAS FAILED TO MATERIALIZE. THE NAM PUTS THE BEST CHANCE OF LIGHT SNOW JUST TO THE NORTHEAST OF OUR CWA AFTER MIDNIGHT. OVERALL CONFIDENCE IN SEEING LIGHT SNOWFALL ACCUMULATIONS ACROSS OUR NORTHEAST ZONES HAS DECREASED AND THEREFORE HAVE TRENDED SLIGHTLY LOWER WITH POPS. PREV DISCUSSION... /ISSUED 245 PM CST MON JAN 21 2013/ SHORT TERM...TONIGHT AND TUESDAY. FOCUS IS ON LIGHT SNOW POTENTIAL FOR TONIGHT. THE PATTERN ALOFT PLACED AN UPPER RIDGE AXIS ALONG THE WEST COAST STATES...NORTHWEST FLOW ACROSS THE INTERIOR CONUS WITH AN UPPER LOW ORIENTED FM ONTARIO SOUTH THRU THE OHIO VALLEY. AN ARCTIC AIRMASS HAD SETTLED ACROSS THE DAKOTAS THRU THE EASTERN PORTIONS OF THE CENTRAL PLAINS STATES...AND AT THE SURFACE...A 1032MB SURFACE HIGH WAS ORIENTED ALONG THE MISSOURI RIVER. BANDS OF SNOW DEVELOPED THIS MORNING ACROSS OUR NORTHERN/EASTERN ZONES AS A 150KT JET STREAK NOSED SOUTH ALONG THE MISSOURI RIVER...DRIVING SHEARED ENERGY SOUTH ACROSS THE PLAINS. THE SNOW DEVELOPED IN AN AREA OF MID LEVEL FRONTOGENESIS AND THE AREA OF LIFT WAS ALSO DEPICTED WELL ON THE 290K ISENTROPIC SURFACE. HAD A REPORT OF SOME AREAS PICKING UP SNOW OF A HALF INCH TO THREE QUARTERS OF AN INCH IN THE HEAVIER BANDS...AND VSBYS DROPPED BELOW TWO MILES AT TIMES. MODELS ARE PRETTY CONSISTENT INDICATING THAT THIS INITIAL ROUND OF SNOW WILL CONTINUE TO WIND DOWN THIS AFTERNOON IN DECREASING LIFT/DYNAMICS...WITH ANOTHER ROUND OF SNOW SETTING UP THIS EVENING/TONIGHT. LIFT INCREASES AGAIN TONIGHT WITH A 130KT JET STREAK NOSING SOUTH THRU EASTERN NEBRASKA...AGAIN NEAR THE MISSOURI RIVER. THIS AGAIN DRIVES SHEARED ENERGY SOUTH AND ISENTROPIC LIFT INCREASES THIS EVENING WITH BETTER LIFT HEADING INTO TONIGHT. SNOW IS EXPECTED TO REDEVELOP ACROSS OUR NORTHERN ZONES INITIALLY AND SPREAD SOUTH AND AFFECT OUR EAST/NORTHEAST ZONES OVERNIGHT...OR GENERALLY PRETTY MUCH ACROSS THE SAME AREAS WHICH SAW SNOWFALL TODAY. SNOWFALL ACCUMULATIONS ARE EXPECTED TO REMAIN RATHER LIGHT...GENERALLY A DUSTING TO UP TO ONE INCH. THE LIGHT SNOWFALL POTENTIAL IS BEST SUPPORTED BY SREF...12Z SPC WRF AND RUC/RAP. DECIDED TO HANDLE THIS EVENT WITH HIGH POPS AND LOW SNOWFALL ACCUMULATIONS. SET UP LOOKS GOOD FOR SNOW BUT AMOUNTS SHOULD NOT BE HIGH. CURRENT FORECAST HAS FOG POTENTIAL TONIGHT...AND LEFT THIS IN AS DEVELOPMENT STILL LOOKS POSSIBLE ALONG OUR SOUTHERN/WESTERN ZONES IN LIGHT EASTERLY RETURN FLOW FM SFC HIGH TO THE EAST AND THESE LOCATIONS WILL ALSO BE ON THE EDGE/PERIPHERY OF THE STRATUS. HRRR VSBY PROGS ACTUALLY INDICATE POTENTIAL FOR DENSE FOG ACROSS PORTIONS OF WESTERN NEB/KS WITH OUR WESTERN ZONES ON THE EDGE OF THIS. DEFINITELY SOMETHING TO KEEP AN EYE ON TONIGHT. SOME FLURRIES MAY LINGER FOR A FEW HOURS TUESDAY MORNING IN OUR NORTHEAST...WITH POTENTIAL FOR FOG REMAINING IN THE MORNING IN OUR SOUTH/WEST. THE SURFACE RIDGE AXIS CONTINUES TO GRADUALLY SHIFT EAST AND HEIGHTS BEGIN TO RISE ACROSS THE PLAINS. LOW CLOUDS BEGIN TO ERODE FM WEST/EAST BUT STILL NOT LOOKING FOR A WHOLE LOT OF IMPROVEMENT IN TEMPS TOMORROW AFTN IN OUR EAST...ALTHOUGH SOME LOW 20S ARE POSSIBLE. TO THE WEST...IN INCREASING INSOLATION AND PROXIMITY TO WARMER AIR...READINGS NEAR 40F ARE POSSIBLE. LONG TERM...TUESDAY NIGHT THROUGH MONDAY. PRIMARY FORECAST CONCERN LIES WITH TEMPERATURES. NORTHWESTERLY FLOW IN THE UPPER LEVELS IS EXPECTED TO BE IN PLACE AT THE START OF THE LONG TERM PERIOD...WITH BROAD TROUGHING IN PLACE OVER THE MIDWEST/EAST COAST AND A RIDGE AXIS EXTENDING THROUGH THE ROCKIES AND INTO CANADA. THE SURFACE PATTERN STARTS OUT WITH LIGHT GENERALLY SOUTHERLY WINDS ACROSS THE CWA...AS HIGH PRESSURE ENCOMPASSES MUCH OF THE CONUS EAST OF THE MO RIVER...AND A TROUGH OF LOW PRESSURE REMAINS OVER THE HIGH PLAINS. THE FORECAST THROUGH WEDNESDAY NIGHT REMAINS DRY WITH NO NOTABLE SYSTEMS TAKING AIM ON THE REGION...THOUGH AN UPPER LEVEL DISTURBANCE SWINGING OUT OF CANADA AND INTO THE GREAT LAKES REGION DURING THE DAYTIME HOURS ON WEDNESDAY WILL HAVE SOME IMPACT ON OUR CWA. A BACKDOOR FRONT WILL WORK ITS WAY INTO THE AREA FROM THE N/NE...BRINGING NE/E WINDS AND IS EXPECTED TO KEEP ROUGHLY THE NORTHEASTERN HALF OF THE CWA IN THE MID/UPPER 30S FOR HIGHS...WITH THE SOUTH AND WEST IN THE 40S. A LITTLE MORE UNCERTAINTY IN THE FORECAST ARISES AS WE GET INTO THURSDAY...MAINLY WITH THE TIMING OF ANOTHER COLD FRONT EXPECTED TO PUSH THROUGH THE NRN/CENTRAL PLAINS. ANOTHER...STRONGER UPPER LEVEL DISTURBANCE WILL AGAIN PUSH OUT OF CENTRAL CANADA AND MOVE SOUTHEAST THROUGH THE NORTHERN PLAINS AND EVENTUALLY INTO THE MIDWEST. THE 12Z NAM WAS AN OUTLIER COMPARED TO OTHER MODELS WITH THE TIMING OF THE FRONT...ALREADY MAKING A GOOD PUSH THROUGH THE CWA BY MIDDAY THURSDAY...WITH THE EC/GFS/SREF ALL SLOWER AND BRINGING THE FRONT TROUGH MORE DURING THE THURS EVENING/OVERNIGHT HOURS. KEPT THE FORECAST CLOSER TO THOSE SLOWER SOLUTIONS. AS HAS BEEN THE CASE THE PAST FEW DAYS...MODELS CONTINUING TO SHOW BETTER PRECIPITATION CHANCES REMAINING WELL TO THE SOUTH OF THE CWA CLOSER TO THE MAIN SFC WARM FRONT...AND TO THE NORTH WITH THE BETTER UPPER LEVEL FORCING. THIS FRONT WILL USHER IS COLDER AIR AND LOWER TEMPERATURES FOR FRIDAY...AND FORECAST HIGHS RANGE FROM THE LOWER 20S IN THE NORTHEAST TO THE UPPER 30S IN THE SOUTHWEST. ALREADY FRIDAY NIGHT...MODELS IN GOOD AGREEMENT SHOWING THIS LATEST BATCH OF COLDER STARTING TO SHIFT OFF TO THE EAST OF THE CWA...AS RIDGING STARTS TO REAMPLIFY OVER THE ROCKIES WITH ANOTHER UPPER LEVEL TROUGH OF THE WEST COAST. THIS RIDGE LOOKS TO REMAIN THE MAIN PLAYER IN THE UPPER LEVELS THROUGH AT LEAST THE UPCOMING WEEKEND...WITH A LITTLE MORE UNCERTAINTY WHETHER IT CONTINUES INTO MONDAY LIKE THE 12Z EC IS SHOWING /THE GFS SHOWS ANOTHER FRONT MOVING THROUGH/. FORECAST CURRENTLY CALLING FOR MID 30S/MID 40S FOR HIGHS ON SAT...WITH MID 40S/LOWER 50S FOR SUN/MON. IF THE ECMWF SOLUTION IS THE ONE OTHER MODELS TREND TOO...MAY NEED UPWARD TWEAKS FOR SUN/MON TEMPS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ AVIATION...HALBLAUB 1206
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1137 PM CST MON JAN 21 2013 .AVIATION.../06Z GRI TAF THROUGH 06Z TUESDAY NIGHT/ THRU 12Z: MVFR CIGS SEEM TO BE EXPANDING WHICH INCREASES CONFIDENCE THAT MVFR CIGS WILL PREVAIL...BUT CONFIDENCE IS ONLY AVERAGE BECAUSE THE EDGE IS BETWEEN ODX AND GRI. LIGHT SE WINDS 5 KTS OR LESS. UNRESTRICTED VSBYS. TUE: MVFR OR LOW-END VFR OVC THRU 20Z...BUT AS TEMPS INCREASE CLEARING WILL MOVE THRU AFTER 21Z. SE WINDS AT OR BELOW 10 KTS. UNRESTRICTED VSBYS. TUE EVE: ESSENTIALLY VFR SKC. SE WINDS AROUND 5 KTS. && .PREV DISCUSSION... /ISSUED 957 PM CST MON JAN 21 2013/ UPDATE...THE RUC CONTINUES TO GENERATE LIGHT SNOW ACROSS OUR NORTHEAST ZONES THIS EVENING...WHICH THUS FAR HAS FAILED TO MATERIALIZE. THE NAM PUTS THE BEST CHANCE OF LIGHT SNOW JUST TO THE NORTHEAST OF OUR CWA AFTER MIDNIGHT. OVERALL CONFIDENCE IN SEEING LIGHT SNOWFALL ACCUMULATIONS ACROSS OUR NORTHEAST ZONES HAS DECREASED AND THEREFORE HAVE TRENDED SLIGHTLY LOWER WITH POPS. PREV DISCUSSION... /ISSUED 245 PM CST MON JAN 21 2013/ SHORT TERM...TONIGHT AND TUESDAY. FOCUS IS ON LIGHT SNOW POTENTIAL FOR TONIGHT. THE PATTERN ALOFT PLACED AN UPPER RIDGE AXIS ALONG THE WEST COAST STATES...NORTHWEST FLOW ACROSS THE INTERIOR CONUS WITH AN UPPER LOW ORIENTED FM ONTARIO SOUTH THRU THE OHIO VALLEY. AN ARCTIC AIRMASS HAD SETTLED ACROSS THE DAKOTAS THRU THE EASTERN PORTIONS OF THE CENTRAL PLAINS STATES...AND AT THE SURFACE...A 1032MB SURFACE HIGH WAS ORIENTED ALONG THE MISSOURI RIVER. BANDS OF SNOW DEVELOPED THIS MORNING ACROSS OUR NORTHERN/EASTERN ZONES AS A 150KT JET STREAK NOSED SOUTH ALONG THE MISSOURI RIVER...DRIVING SHEARED ENERGY SOUTH ACROSS THE PLAINS. THE SNOW DEVELOPED IN AN AREA OF MID LEVEL FRONTOGENESIS AND THE AREA OF LIFT WAS ALSO DEPICTED WELL ON THE 290K ISENTROPIC SURFACE. HAD A REPORT OF SOME AREAS PICKING UP SNOW OF A HALF INCH TO THREE QUARTERS OF AN INCH IN THE HEAVIER BANDS...AND VSBYS DROPPED BELOW TWO MILES AT TIMES. MODELS ARE PRETTY CONSISTENT INDICATING THAT THIS INITIAL ROUND OF SNOW WILL CONTINUE TO WIND DOWN THIS AFTERNOON IN DECREASING LIFT/DYNAMICS...WITH ANOTHER ROUND OF SNOW SETTING UP THIS EVENING/TONIGHT. LIFT INCREASES AGAIN TONIGHT WITH A 130KT JET STREAK NOSING SOUTH THRU EASTERN NEBRASKA...AGAIN NEAR THE MISSOURI RIVER. THIS AGAIN DRIVES SHEARED ENERGY SOUTH AND ISENTROPIC LIFT INCREASES THIS EVENING WITH BETTER LIFT HEADING INTO TONIGHT. SNOW IS EXPECTED TO REDEVELOP ACROSS OUR NORTHERN ZONES INITIALLY AND SPREAD SOUTH AND AFFECT OUR EAST/NORTHEAST ZONES OVERNIGHT...OR GENERALLY PRETTY MUCH ACROSS THE SAME AREAS WHICH SAW SNOWFALL TODAY. SNOWFALL ACCUMULATIONS ARE EXPECTED TO REMAIN RATHER LIGHT...GENERALLY A DUSTING TO UP TO ONE INCH. THE LIGHT SNOWFALL POTENTIAL IS BEST SUPPORTED BY SREF...12Z SPC WRF AND RUC/RAP. DECIDED TO HANDLE THIS EVENT WITH HIGH POPS AND LOW SNOWFALL ACCUMULATIONS. SET UP LOOKS GOOD FOR SNOW BUT AMOUNTS SHOULD NOT BE HIGH. CURRENT FORECAST HAS FOG POTENTIAL TONIGHT...AND LEFT THIS IN AS DEVELOPMENT STILL LOOKS POSSIBLE ALONG OUR SOUTHERN/WESTERN ZONES IN LIGHT EASTERLY RETURN FLOW FM SFC HIGH TO THE EAST AND THESE LOCATIONS WILL ALSO BE ON THE EDGE/PERIPHERY OF THE STRATUS. HRRR VSBY PROGS ACTUALLY INDICATE POTENTIAL FOR DENSE FOG ACROSS PORTIONS OF WESTERN NEB/KS WITH OUR WESTERN ZONES ON THE EDGE OF THIS. DEFINITELY SOMETHING TO KEEP AN EYE ON TONIGHT. SOME FLURRIES MAY LINGER FOR A FEW HOURS TUESDAY MORNING IN OUR NORTHEAST...WITH POTENTIAL FOR FOG REMAINING IN THE MORNING IN OUR SOUTH/WEST. THE SURFACE RIDGE AXIS CONTINUES TO GRADUALLY SHIFT EAST AND HEIGHTS BEGIN TO RISE ACROSS THE PLAINS. LOW CLOUDS BEGIN TO ERODE FM WEST/EAST BUT STILL NOT LOOKING FOR A WHOLE LOT OF IMPROVEMENT IN TEMPS TOMORROW AFTN IN OUR EAST...ALTHOUGH SOME LOW 20S ARE POSSIBLE. TO THE WEST...IN INCREASING INSOLATION AND PROXIMITY TO WARMER AIR...READINGS NEAR 40F ARE POSSIBLE. LONG TERM...TUESDAY NIGHT THROUGH MONDAY. PRIMARY FORECAST CONCERN LIES WITH TEMPERATURES. NORTHWESTERLY FLOW IN THE UPPER LEVELS IS EXPECTED TO BE IN PLACE AT THE START OF THE LONG TERM PERIOD...WITH BROAD TROUGHING IN PLACE OVER THE MIDWEST/EAST COAST AND A RIDGE AXIS EXTENDING THROUGH THE ROCKIES AND INTO CANADA. THE SURFACE PATTERN STARTS OUT WITH LIGHT GENERALLY SOUTHERLY WINDS ACROSS THE CWA...AS HIGH PRESSURE ENCOMPASSES MUCH OF THE CONUS EAST OF THE MO RIVER...AND A TROUGH OF LOW PRESSURE REMAINS OVER THE HIGH PLAINS. THE FORECAST THROUGH WEDNESDAY NIGHT REMAINS DRY WITH NO NOTABLE SYSTEMS TAKING AIM ON THE REGION...THOUGH AN UPPER LEVEL DISTURBANCE SWINGING OUT OF CANADA AND INTO THE GREAT LAKES REGION DURING THE DAYTIME HOURS ON WEDNESDAY WILL HAVE SOME IMPACT ON OUR CWA. A BACKDOOR FRONT WILL WORK ITS WAY INTO THE AREA FROM THE N/NE...BRINGING NE/E WINDS AND IS EXPECTED TO KEEP ROUGHLY THE NORTHEASTERN HALF OF THE CWA IN THE MID/UPPER 30S FOR HIGHS...WITH THE SOUTH AND WEST IN THE 40S. A LITTLE MORE UNCERTAINTY IN THE FORECAST ARISES AS WE GET INTO THURSDAY...MAINLY WITH THE TIMING OF ANOTHER COLD FRONT EXPECTED TO PUSH THROUGH THE NRN/CENTRAL PLAINS. ANOTHER...STRONGER UPPER LEVEL DISTURBANCE WILL AGAIN PUSH OUT OF CENTRAL CANADA AND MOVE SOUTHEAST THROUGH THE NORTHERN PLAINS AND EVENTUALLY INTO THE MIDWEST. THE 12Z NAM WAS AN OUTLIER COMPARED TO OTHER MODELS WITH THE TIMING OF THE FRONT...ALREADY MAKING A GOOD PUSH THROUGH THE CWA BY MIDDAY THURSDAY...WITH THE EC/GFS/SREF ALL SLOWER AND BRINGING THE FRONT TROUGH MORE DURING THE THURS EVENING/OVERNIGHT HOURS. KEPT THE FORECAST CLOSER TO THOSE SLOWER SOLUTIONS. AS HAS BEEN THE CASE THE PAST FEW DAYS...MODELS CONTINUING TO SHOW BETTER PRECIPITATION CHANCES REMAINING WELL TO THE SOUTH OF THE CWA CLOSER TO THE MAIN SFC WARM FRONT...AND TO THE NORTH WITH THE BETTER UPPER LEVEL FORCING. THIS FRONT WILL USHER IS COLDER AIR AND LOWER TEMPERATURES FOR FRIDAY...AND FORECAST HIGHS RANGE FROM THE LOWER 20S IN THE NORTHEAST TO THE UPPER 30S IN THE SOUTHWEST. ALREADY FRIDAY NIGHT...MODELS IN GOOD AGREEMENT SHOWING THIS LATEST BATCH OF COLDER STARTING TO SHIFT OFF TO THE EAST OF THE CWA...AS RIDGING STARTS TO REAMPLIFY OVER THE ROCKIES WITH ANOTHER UPPER LEVEL TROUGH OF THE WEST COAST. THIS RIDGE LOOKS TO REMAIN THE MAIN PLAYER IN THE UPPER LEVELS THROUGH AT LEAST THE UPCOMING WEEKEND...WITH A LITTLE MORE UNCERTAINTY WHETHER IT CONTINUES INTO MONDAY LIKE THE 12Z EC IS SHOWING /THE GFS SHOWS ANOTHER FRONT MOVING THROUGH/. FORECAST CURRENTLY CALLING FOR MID 30S/MID 40S FOR HIGHS ON SAT...WITH MID 40S/LOWER 50S FOR SUN/MON. IF THE ECMWF SOLUTION IS THE ONE OTHER MODELS TREND TOO...MAY NEED UPWARD TWEAKS FOR SUN/MON TEMPS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
116 PM EST TUE JAN 22 2013 .SYNOPSIS... COLDER AIR WILL ARRIVE ON GUSTY WEST TO NORTHWEST WINDS THIS MORNING...WHICH WILL ALLOW LAKE EFFECT SNOWS TO DEVELOP NORTH OF THE NEW YORK THRUWAY. OUTSIDE OF THE LAKE EFFECT SNOW...PARTLY TO MOSTLY CLOUDY SKIES AND SCATTERED SNOW SHOWERS OR FLURRIES ARE EXPECTED. THIS ACTIVITY WILL DIMINISH ON WEDNESDAY AS THE NEXT CLIPPER MOVES IN. HIGH PRESSURE WILL THEN BUILD IN ON THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1020 AM UPDATE... INTERESTING MESO WX DAY CONTINUES. SWD MVMNT OF LES SNOW BAND ACRS ERN LAKE ONTARIO HAS SLOWED OVER THE PAST HR...WITH FETCH BEING SOMEWHAT REDUCED. THIS HAS RESULTED IN THE WEAKENING OF THE BAND ACRS NRN ONEIDA COUNTY. THERE ARE SOME HINTS IN RDR REFLEECTIVITY THAT A MESO-VORTEX MAY BE DVLPNG ALONG THE BAND JUST W OF ROC. 00Z MESO MDLS WERE HINTING AT THIS DVLPMNT. THIS REMAINS A LOW CONFIDENCE FCST...BUT WE THINK THE BAND WILL REMAIN PRETTY MUCH WHERE IT IS UNTIL DROPPING SWD LATER THIS AFTN (MAYBE WITH THE PSSG OF THE MESO-VORT). NAM12 AND RUC STILL INDICATE A QUICKER SWD MVMNT OF THE BAND (18-29Z INTO NRN CWA) ALBIET IN A WEAKER STATE. GIVEN THE UNCERTAINTY...NO CHGS WILL BE MADE TO THE CRNT FCST. WE WILL RE-EVALUATE ALL HEADLINES WITH THE AFTN PCKG. THANX BUF FOR COLLAB. PREV BLO... 850 AM UPDATE... LAKE BAND HAS BEGUN TO SHOW A SWD DRIFT ACRS SRN LAKE ONTARIO...WITH LTL MVMNT NOTED THUS FAR ACRS THE ERN SXNS. SOME INDICATIONS IN THE MESO-MDLS THAT WE`LL SEE ANOTHER MESO-VORTEX MOVG EWD ALONG THE BNDRY THIS AFTN. SIG DIFFS IN THE SHORT TERM GDNC W/ RESPECT TO THE SWD MVMNT OF THE BNDRY...WITH ARW SUGGESTING THE SLOWEST MVMNT...WITH RUC SUGGESTING IT OVG INTO TEH SYR AREA BY 18Z. WE WILL CONTINUE TO MONITOR BUT ARE THINKNG THAT THE SWD DRIFT WILL BE A BIT LATER THAN CRNTLY FCST (LOW CONFIDENCE)...SO WARNINGS HAVE BEEN DELAYED TIL 18Z FOR ONON/MAD/SRN ONEIDA. IF ARW IS CORRECT...EVEN THIS TIMING WILL BE TOO SLOW. NEEDLESS TO SAY...AN INTERESTING MESO MET DAY. ELSEWHERE...SCT -SHSN OFF LAKE ERIE ACRS TNE SRN TIER INTO NE PA. PREV BLO... 330 AM UPDATE... COMPLICATED SFC PATTERN ACRS THE AREA TONIGHT. SFC LOW ACRS SRN ONTARIO IS SLIDING EAST ALONG STATIONARY FRONT LURKING FM THE MAINE COAST WWD INTO THE MOHAWK VLY. THIS FRNT SEPARATES WEST WINDS ACRS FAR NRN ZONES FM EAST-NORTHEAST WINDS OVR THE DACKS AND SRN CANADA. LK EFFECT BAND THAT TRAVERSED THRU SYRACUSE AND HAS LIFTED NORTH INTO ONEIDA CNTY LKLY DUE TO UL WVS TRAVERSING ACRS THE AREA. MAIN PART OF THE LAKE BAND TOOK ON NORTH TO SOUTH CONFIGURATION AS IT DRIFTED THRU ONONDAGA CNTY AND IS NOW BECOMING MORE SINGULAR IN ORIENTATION. WEST-SOUTHWEST FLOW IS OCCURRING NOW WITH UPSTREAM CONNECTION TO LK HURON. HIRES AND NAM12 INDICATES SFC LOW WL HEAD EAST BY 12Z DUE TO PRESSURE FALLS AND AS IT PASSES INTO THE DACKS WINDS SHUD TURN MORE NWRLY AS IT DOES SO. THIS WL LKLY START TO SHIFT THE LK BAND JUST A TAD FURTHER SOUTH INTO NRN ONEIDA CNTY. HV GONE CATEGORICAL FOR ONEIDA CNTY BTWN 12Z-18Z FOR SNOW SHOWERS WITH OCNLY HEAVY SNOW. LK EFFECT SNOW SQUALLS CAN BE EXPECTED ACRS NRN ZONES NORTH OF THE NEW YORK THRUWAY WITH TOTALS THRU 00Z WED APPCHG A FOOT ACRS NWRN ONEIDA CNTY. LK EFFECT SNOW WARNING APPEARS REASONABLE FOR ALL OF ONEIDA CNTY TDA. EXTREME INSTABILITY WL BE PRESENT WITH LK-INDUCED CAPES > 1000 J/KG WITH INVERSION DEPTHS OF ARND 10KFT. THIS MAY PRODUCE SNOWFALL RATES OF ARND 2 INCHES PER HR AT TIMES TDA. HIRES MODELS INDICATE BAND WL BEGIN TO SLIP SOUTH AFT 18Z THIS AFTN INTO ONONDAGA/MADISON CNTYS THO HOW FAR SOUTH RMNS TO BE SEEN. 6-HR AMNTS OF 2-5 INCHES IN THESE CNTYS WL BE POSSIBLE BY 00Z WED. AFTN MAXES EXPECTED TO RISE INTO THE LWR TEENS TDA AS COLD AIRMASS RMNS LOCKED IN ACRS CWA. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... 330 AM UPDATE... SNOW BAND WILL DROP FURTHER SOUTH OVRNGT WITH HVY SNOW INTO ONONDAGA/MADISON CNTYS AND HV UPGRADED THESE CNTYS TO WARNINGS. OVRNGT MINS WL DIP IN THE SINGLE DIGITS AND WITH WINDS ARND 10 MPH, WIND CHILL VALUES WILL DIP BLO -15F TONIGHT FOR NY COUNTIES EAST OF I-81. THUS HV OPTED TO ISSUE A WIND CHILL ADVISORY FOR THESE LOCALES FROM 05Z TONIGHT THRU 15Z WED. ANOTHER CLIPPER ON TAP FOR WEDNESDAY WITH SNOW EXPECTED ONCE AGAIN WITH AMNTS BTWN 0.5 AND 1 INCH. TEMPS WL ONCE AGAIN BE IN THE TEENS ON WEDNESDAY AS NRLY FLOW PROVIDES A STEADY FLOW OF CLD AIR FM CANADA. HIPRES BUILDS IN BRIEFLY FOR THURSDAY SHUTTING OFF PCPN AND ALLOWING TEMPS TO WARM SEVERAL DEGREES ABV VALUES EARLY IN THE WEEK. NEXT SYSTEM WL MV IN FRI MRNG BUT IS SLOW TO ARRIVE WITH HIPRES HOLDING TIGHT TO CWA THRU 12Z. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... MEDIUM RANGE MODELS CONTINUE TO SHOW FAIR AGREEMENT THROUGH THE EXTENDED PERIOD. INITIALLY THE PERIOD BEGINS WITH SFC LOW PRES IN THE MID ATLANTIC REGION LIFTING NORTHEAST ALONG THE NEW ENGLAND COAST. THE ECMWF IS MUCH STRONGER AND FARTHER NORTH THAN THE GFS WITH THIS FEATURE BUT SYSTEM REMAINS RATHER WEAK UNTIL ITS WELL EAST OF AREA. WILL CONTINUE WITH HIGH CHC/LIKELY POPS FRIDAY NIGHT WITH HIGHEST POPS NE PA AND SOUTHERN TIER. SATURDAY THROUGH SUNDAY, AREA WILL BE UNDER A COLD AIRMASS WITH NW FLOW. SCATTERED SNOW SHOWERS WILL PERSIST FOR MUCH OF CENTRAL NEW YORK AS TEMPS RUN 5 TO 10 DEGREES BELOW NORMAL. MONDAY THROUGH TUESDAY...UPPER LEVEL TROF WILL LIFT OUT OF THE NORTHEAST AS A FLAT RIDGE BUILDS IN. TEMPS WILL MODERATE BACK TO SEASONAL OR SLIGHTLY ABOVE SEASONAL NORMALS. THERE ALSO IS THE CHC FOR LIGHT SNOW SHOWERS DUE TO THE WARM AIR ADVECTION. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... LAKE EFFECT SNOW BAND SOUTHEAST OF LAKE ONTARIO WILL CONTINUE SLOW PROGRESS SOUTHWARD THROUGH EARLY EVENING THEN GRADUALLY WEAKEN OVERNIGHT. AT KRME, LAKE BAND IS CURRENTLY OVER TERMINAL WITH LOW MVFR CONDITIONS EXPECTED THROUGH EARLY EVENING WITH OCCASIONAL IFR THROUGH LATE AFTERNOON. OVERNIGHT, BAND WILL RESIDE SOUTH OF AREA WITH PRIMARILY VFR CONDITIONS EXPECTED. AT KSYR, LAKE BAND WILL DROP INTO THE AIRPORT BY 21Z. FROM LATE THIS AFTERNOON THROUGH LATE TONIGHT IFR CONDITIONS WILL PERSISTS WITH OCCASIONAL BELOW AIRPORT MINS FROM LATE THIS AFTERNOON THROUGH EARLY EVENING. AFTER 09Z, BAND IS EXPECTED TO WEAKEN WITH CONDITIONS IMPROVING TO MVFR. AT KITH/KBGM/KELM, DIURNAL SNOW SHOWERS HAVE DEVELOPED DUE TO VERY UNSTABLE LOW LEVELS. FOR THIS REASON INCLUDED OCCASIONAL IFR SNOW SHOWERS THROUGH LATE AFTERNOON. REMAINDER OF PERIOD SHOULD BE PRIMARILY VFR WITH STRATO CU AROUND 3500 FT. AFTER 18Z WED MORE SNOW SHOWERS ARE LIKELY WITH POSSIBLE IFR. AT KAVP, CONDITIONS WILL BE PRIMARILY VFR WITH CIGS AROUND 4K FT. WEST WINDS 15 TO 20 KTS WITH GUSTS TO 25-30 KTS. THIS EVENING WINDS WILL DECREASE TO 5-10 KNOTS AND CONTINUE THROUGH WEDNESDAY. .OUTLOOK... WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...PRIMARILY VFR. FRI... IFR CONDITIONS POSSIBLE IN SNOW. FRIDAY NIGHT/SATURDAY...MVFR SNOW SHOWERS RESTRICTIONS LIKELY FOR CENTRAL NY. SUNDAY...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EST WEDNESDAY FOR NYZ009-036-037-045-046-057-062. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST WEDNESDAY FOR NYZ018- 036-037. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST WEDNESDAY FOR NYZ009. && $$ SYNOPSIS...PVN NEAR TERM...PVN SHORT TERM...PVN LONG TERM...RRM AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1029 AM EST TUE JAN 22 2013 .SYNOPSIS... COLDER AIR WILL ARRIVE ON GUSTY WEST TO NORTHWEST WINDS THIS MORNING...WHICH WILL ALLOW LAKE EFFECT SNOWS TO DEVELOP NORTH OF THE NEW YORK THRUWAY. OUTSIDE OF THE LAKE EFFECT SNOW...PARTLY TO MOSTLY CLOUDY SKIES AND SCATTERED SNOW SHOWERS OR FLURRIES ARE EXPECTED. THIS ACTIVITY WILL DIMINISH ON WEDNESDAY AS THE NEXT CLIPPER MOVES IN. HIGH PRESSURE WILL THEN BUILD IN ON THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1020 AM UPDATE... INTERESTING MESO WX DAY CONTINUES. SWD MVMNT OF LES SNOW BAND ACRS ERN LAKE ONTARIO HAS SLOWED OVER THE PAST HR...WITH FETCH BEING SOMEWHAT REDUCED. THIS HAS RESULTED IN THE WEAKENING OF THE BAND ACRS NRN ONEIDA COUNTY. THERE ARE SOME HINTS IN RDR REFLEECTIVITY THAT A MESO-VORTEX MAY BE DVLPNG ALONG THE BAND JUST W OF ROC. 00Z MESO MDLS WERE HINTING AT THIS DVLPMNT. THIS REMAINS A LOW CONFIDENCE FCST...BUT WE THINK THE BAND WILL REMAIN PRETTY MUCH WHERE IT IS UNTIL DROPPING SWD LATER THIS AFTN (MAYBE WITH THE PSSG OF THE MESO-VORT). NAM12 AND RUC STILL INDICATE A QUICKER SWD MVMNT OF THE BAND (18-29Z INTO NRN CWA) ALBIET IN A WEAKER STATE. GIVEN THE UNCERTAINTY...NO CHGS WILL BE MADE TO THE CRNT FCST. WE WILL RE-EVALUATE ALL HEADLINES WITH THE AFTN PCKG. THANX BUF FOR COLLAB. PREV BLO... 850 AM UPDATE... LAKE BAND HAS BEGUN TO SHOW A SWD DRIFT ACRS SRN LAKE ONTARIO...WITH LTL MVMNT NOTED THUS FAR ACRS THE ERN SXNS. SOME INDICATIONS IN THE MESO-MDLS THAT WE`LL SEE ANOTHER MESO-VORTEX MOVG EWD ALONG THE BNDRY THIS AFTN. SIG DIFFS IN THE SHORT TERM GDNC W/ RESPECT TO THE SWD MVMNT OF THE BNDRY...WITH ARW SUGGESTING THE SLOWEST MVMNT...WITH RUC SUGGESTING IT OVG INTO TEH SYR AREA BY 18Z. WE WILL CONTINUE TO MONITOR BUT ARE THINKNG THAT THE SWD DRIFT WILL BE A BIT LATER THAN CRNTLY FCST (LOW CONFIDENCE)...SO WARNINGS HAVE BEEN DELAYED TIL 18Z FOR ONON/MAD/SRN ONEIDA. IF ARW IS CORRECT...EVEN THIS TIMING WILL BE TOO SLOW. NEEDLESS TO SAY...AN INTERESTING MESO MET DAY. ELSEWHERE...SCT -SHSN OFF LAKE ERIE ACRS TNE SRN TIER INTO NE PA. PREV BLO... 330 AM UPDATE... COMPLICATED SFC PATTERN ACRS THE AREA TONIGHT. SFC LOW ACRS SRN ONTARIO IS SLIDING EAST ALONG STATIONARY FRONT LURKING FM THE MAINE COAST WWD INTO THE MOHAWK VLY. THIS FRNT SEPARATES WEST WINDS ACRS FAR NRN ZONES FM EAST-NORTHEAST WINDS OVR THE DACKS AND SRN CANADA. LK EFFECT BAND THAT TRAVERSED THRU SYRACUSE AND HAS LIFTED NORTH INTO ONEIDA CNTY LKLY DUE TO UL WVS TRAVERSING ACRS THE AREA. MAIN PART OF THE LAKE BAND TOOK ON NORTH TO SOUTH CONFIGURATION AS IT DRIFTED THRU ONONDAGA CNTY AND IS NOW BECOMING MORE SINGULAR IN ORIENTATION. WEST-SOUTHWEST FLOW IS OCCURRING NOW WITH UPSTREAM CONNECTION TO LK HURON. HIRES AND NAM12 INDICATES SFC LOW WL HEAD EAST BY 12Z DUE TO PRESSURE FALLS AND AS IT PASSES INTO THE DACKS WINDS SHUD TURN MORE NWRLY AS IT DOES SO. THIS WL LKLY START TO SHIFT THE LK BAND JUST A TAD FURTHER SOUTH INTO NRN ONEIDA CNTY. HV GONE CATEGORICAL FOR ONEIDA CNTY BTWN 12Z-18Z FOR SNOW SHOWERS WITH OCNLY HEAVY SNOW. LK EFFECT SNOW SQUALLS CAN BE EXPECTED ACRS NRN ZONES NORTH OF THE NEW YORK THRUWAY WITH TOTALS THRU 00Z WED APPCHG A FOOT ACRS NWRN ONEIDA CNTY. LK EFFECT SNOW WARNING APPEARS REASONABLE FOR ALL OF ONEIDA CNTY TDA. EXTREME INSTABILITY WL BE PRESENT WITH LK-INDUCED CAPES > 1000 J/KG WITH INVERSION DEPTHS OF ARND 10KFT. THIS MAY PRODUCE SNOWFALL RATES OF ARND 2 INCHES PER HR AT TIMES TDA. HIRES MODELS INDICATE BAND WL BEGIN TO SLIP SOUTH AFT 18Z THIS AFTN INTO ONONDAGA/MADISON CNTYS THO HOW FAR SOUTH RMNS TO BE SEEN. 6-HR AMNTS OF 2-5 INCHES IN THESE CNTYS WL BE POSSIBLE BY 00Z WED. AFTN MAXES EXPECTED TO RISE INTO THE LWR TEENS TDA AS COLD AIRMASS RMNS LOCKED IN ACRS CWA. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... 330 AM UPDATE... SNOW BAND WILL DROP FURTHER SOUTH OVRNGT WITH HVY SNOW INTO ONONDAGA/MADISON CNTYS AND HV UPGRADED THESE CNTYS TO WARNINGS. OVRNGT MINS WL DIP IN THE SINGLE DIGITS AND WITH WINDS ARND 10 MPH, WIND CHILL VALUES WILL DIP BLO -15F TONIGHT FOR NY COUNTIES EAST OF I-81. THUS HV OPTED TO ISSUE A WIND CHILL ADVISORY FOR THESE LOCALES FROM 05Z TONIGHT THRU 15Z WED. ANOTHER CLIPPER ON TAP FOR WEDNESDAY WITH SNOW EXPECTED ONCE AGAIN WITH AMNTS BTWN 0.5 AND 1 INCH. TEMPS WL ONCE AGAIN BE IN THE TEENS ON WEDNESDAY AS NRLY FLOW PROVIDES A STEADY FLOW OF CLD AIR FM CANADA. HIPRES BUILDS IN BRIEFLY FOR THURSDAY SHUTTING OFF PCPN AND ALLOWING TEMPS TO WARM SEVERAL DEGREES ABV VALUES EARLY IN THE WEEK. NEXT SYSTEM WL MV IN FRI MRNG BUT IS SLOW TO ARRIVE WITH HIPRES HOLDING TIGHT TO CWA THRU 12Z. && .LONG TERM /FRIDAY THROUGH MONDAY/... MODELS SIMILAR. GRIDS LOOK GOOD. LITTLE CHANGE. PREVIOUS DISCUSSION... MEDIUM RANGE MODELS ARE IN FAIR AGREEMENT THROUGH THE EXTENDED. INITIALLY A SOUTHERN STREAM SYSTEM WILL TRACK THROUGH THE MID ATLANTIC REGION ON FRIDAY. THE ECMWF/CANADIAN IS MUCH FASTER THAN THE GFS, LEANED TOWARD THE ECMWF ENSEMBLE WHICH IS A GOOD COMPROMISE. THURSDAY NIGHT BACKED OFF ON POPS TO JUST CHC THEN CHC/LIKELY ON FRIDAY WITH LIKELY POPS ACROSS THE SOUTHERN TIER AND NE PA. MODELS INDICATE ALL SNOW WITH NO HINT OF ANY WARM LAYER. BEHIND THIS WAVE THE UPPER LEVEL TROF WILL AMPLIFY OVER THE NORTHEAST MAKING FOR A COLD WEEKEND WITH SCATTERED SNOW SHOWERS IN NORTH/NORTHWEST FLOW. BY SUNDAY/MONDAY, UPPER LEVEL HEIGHTS RISE WITH THE AIRMASS EXPECTED TO MODIFY UNDER SOUTHWEST FLOW. && .AVIATION /16Z TUESDAY THROUGH SATURDAY/... 630 AM UPDATE... A COLD WNW FLOW WILL CONTINUE TO GENERATE LAKE EFFECT SNOW. TWO BANDS AFFECTING ALL SITES. THE STRONGER, A SINGLE BAND OF LAKE EFFECT OFF OF LAKE ONTARIO WILL AFFECT ROME ALL MORNING INTO THE AFTN. RME WILL HAVE IFR CONDITIONS AND ALTERNATE MINIMUM. THE BAND WILL DROP FURTHER SOUTH TO SYR MIDDAY AGAIN WITH IFR CONDITIONS AND BELOW ALTERNATE MINIMUM. THIS WILL LAST THERE INTO THE EVENING. THE SECOND BAND OFF OF LAKE ERIE IS NOT AS INTENSE AND NOT CONTINUOUS. THIS HAS BEEN WAVERING ACROSS THE TWIN TIERS AND AFFECTING MOSTLY ELM OF LATE BUT HAS GOTTEN AVP BGM ITH TOO. AGAIN SOME IFR VSBYS BUT NOT SURE IF IT WILL CONTINUE AT THIS RATE. MODEL FORECASTS ONLY SHOW WEAK LAKE EFFECT BUT HAVE UNDERDONE EARLY THIS MORNING. FOR THIS PACKAGE ISSUED ONLY PUT A TEMPO FOR MVFR AT ELM. WEST WINDS AROUND 10 KTS EARLY THIS MORNING. INCREASING TO 10 TO 15 KTS WITH GUSTS TO 25 KTS BY 15Z CONTINUING UNTIL 23Z. WINDS DROPPING TO 10 KTS AT 23Z. .OUTLOOK... WED...MVFR/IFR IN SNOW SHOWERS FOR KRME/KSYR OTHERWISE PRIMARILY VFR. THURSDAY/THURSDAY NIGHT...PRIMARILY VFR. FRI... IFR CONDITIONS POSSIBLE IN SNOW. FRIDAY NIGHT/SATURDAY...MVFR SNOW SHOWERS RESTRICTIONS LIKELY FOR CENTRAL NY. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EST WEDNESDAY FOR NYZ009-036-037-045-046-057-062. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST WEDNESDAY FOR NYZ018- 036-037. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST WEDNESDAY FOR NYZ009. && $$ SYNOPSIS...PVN NEAR TERM...PVN SHORT TERM...PVN LONG TERM...RRM/TAC AVIATION...TAC
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
857 AM EST TUE JAN 22 2013 .SYNOPSIS... COLDER AIR WILL ARRIVE ON GUSTY WEST TO NORTHWEST WINDS THIS MORNING...WHICH WILL ALLOW LAKE EFFECT SNOWS TO DEVELOP NORTH OF THE NEW YORK THRUWAY. OUTSIDE OF THE LAKE EFFECT SNOW...PARTLY TO MOSTLY CLOUDY SKIES AND SCATTERED SNOW SHOWERS OR FLURRIES ARE EXPECTED. THIS ACTIVITY WILL DIMINISH ON WEDNESDAY AS THE NEXT CLIPPER MOVES IN. HIGH PRESSURE WILL THEN BUILD IN ON THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 850 AM UPDATE... LAKE BAND HAS BEGUN TO SHOW A SWD DRIFT ACRS SRN LAKE ONTARIO...WITH LTL MVMNT NOTED THUS FAR ACRS THE ERN SXNS. SOME INDICATIONS IN THE MESO-MDLS THAT WE`LL SEE ANOTHER MESO-VORTEX MOVG EWD ALONG THE BNDRY THIS AFTN. SIG DIFFS IN THE SHORT TERM GDNC W/ RESPECT TO THE SWD MVMNT OF THE BNDRY...WITH ARW SUGGESTING THE SLOWEST MVMNT...WITH RUC SUGGESTING IT OVG INTO TEH SYR AREA BY 18Z. WE WILL CONTINUE TO MONITOR BUT ARE THINKNG THAT THE SWD DRIFT WILL BE A BIT LATER THAN CRNTLY FCST (LOW CONFIDENCE)...SO WARNINGS HAVE BEEN DELAYED TIL 18Z FOR ONON/MAD/SRN ONEIDA. IF ARW IS CORRECT...EVEN THIS TIMING WILL BE TOO SLOW. NEEDLESS TO SAY...AN INTERESTING MESO MET DAY. ELSEWHERE...SCT -SHSN OFF LAKE ERIE ACRS TNE SRN TIER INTO NE PA. PREV BLO... 330 AM UPDATE... COMPLICATED SFC PATTERN ACRS THE AREA TONIGHT. SFC LOW ACRS SRN ONTARIO IS SLIDING EAST ALONG STATIONARY FRONT LURKING FM THE MAINE COAST WWD INTO THE MOHAWK VLY. THIS FRNT SEPARATES WEST WINDS ACRS FAR NRN ZONES FM EAST-NORTHEAST WINDS OVR THE DACKS AND SRN CANADA. LK EFFECT BAND THAT TRAVERSED THRU SYRACUSE AND HAS LIFTED NORTH INTO ONEIDA CNTY LKLY DUE TO UL WVS TRAVERSING ACRS THE AREA. MAIN PART OF THE LAKE BAND TOOK ON NORTH TO SOUTH CONFIGURATION AS IT DRIFTED THRU ONONDAGA CNTY AND IS NOW BECOMING MORE SINGULAR IN ORIENTATION. WEST-SOUTHWEST FLOW IS OCCURRING NOW WITH UPSTREAM CONNECTION TO LK HURON. HIRES AND NAM12 INDICATES SFC LOW WL HEAD EAST BY 12Z DUE TO PRESSURE FALLS AND AS IT PASSES INTO THE DACKS WINDS SHUD TURN MORE NWRLY AS IT DOES SO. THIS WL LKLY START TO SHIFT THE LK BAND JUST A TAD FURTHER SOUTH INTO NRN ONEIDA CNTY. HV GONE CATEGORICAL FOR ONEIDA CNTY BTWN 12Z-18Z FOR SNOW SHOWERS WITH OCNLY HEAVY SNOW. LK EFFECT SNOW SQUALLS CAN BE EXPECTED ACRS NRN ZONES NORTH OF THE NEW YORK THRUWAY WITH TOTALS THRU 00Z WED APPCHG A FOOT ACRS NWRN ONEIDA CNTY. LK EFFECT SNOW WARNING APPEARS REASONABLE FOR ALL OF ONEIDA CNTY TDA. EXTREME INSTABILITY WL BE PRESENT WITH LK-INDUCED CAPES > 1000 J/KG WITH INVERSION DEPTHS OF ARND 10KFT. THIS MAY PRODUCE SNOWFALL RATES OF ARND 2 INCHES PER HR AT TIMES TDA. HIRES MODELS INDICATE BAND WL BEGIN TO SLIP SOUTH AFT 18Z THIS AFTN INTO ONONDAGA/MADISON CNTYS THO HOW FAR SOUTH RMNS TO BE SEEN. 6-HR AMNTS OF 2-5 INCHES IN THESE CNTYS WL BE POSSIBLE BY 00Z WED. AFTN MAXES EXPECTED TO RISE INTO THE LWR TEENS TDA AS COLD AIRMASS RMNS LOCKED IN ACRS CWA. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... 330 AM UPDATE... SNOW BAND WILL DROP FURTHER SOUTH OVRNGT WITH HVY SNOW INTO ONONDAGA/MADISON CNTYS AND HV UPGRADED THESE CNTYS TO WARNINGS. OVRNGT MINS WL DIP IN THE SINGLE DIGITS AND WITH WINDS ARND 10 MPH, WIND CHILL VALUES WILL DIP BLO -15F TONIGHT FOR NY COUNTIES EAST OF I-81. THUS HV OPTED TO ISSUE A WIND CHILL ADVISORY FOR THESE LOCALES FROM 05Z TONIGHT THRU 15Z WED. ANOTHER CLIPPER ON TAP FOR WEDNESDAY WITH SNOW EXPECTED ONCE AGAIN WITH AMNTS BTWN 0.5 AND 1 INCH. TEMPS WL ONCE AGAIN BE IN THE TEENS ON WEDNESDAY AS NRLY FLOW PROVIDES A STEADY FLOW OF CLD AIR FM CANADA. HIPRES BUILDS IN BRIEFLY FOR THURSDAY SHUTTING OFF PCPN AND ALLOWING TEMPS TO WARM SEVERAL DEGREES ABV VALUES EARLY IN THE WEEK. NEXT SYSTEM WL MV IN FRI MRNG BUT IS SLOW TO ARRIVE WITH HIPRES HOLDING TIGHT TO CWA THRU 12Z. && .LONG TERM /FRIDAY THROUGH MONDAY/... MODELS SIMILAR. GRIDS LOOK GOOD. LITTLE CHANGE. PREVIOUS DISCUSSION... MEDIUM RANGE MODELS ARE IN FAIR AGREEMENT THROUGH THE EXTENDED. INITIALLY A SOUTHERN STREAM SYSTEM WILL TRACK THROUGH THE MID ATLANTIC REGION ON FRIDAY. THE ECMWF/CANADIAN IS MUCH FASTER THAN THE GFS, LEANED TOWARD THE ECMWF ENSEMBLE WHICH IS A GOOD COMPROMISE. THURSDAY NIGHT BACKED OFF ON POPS TO JUST CHC THEN CHC/LIKELY ON FRIDAY WITH LIKELY POPS ACROSS THE SOUTHERN TIER AND NE PA. MODELS INDICATE ALL SNOW WITH NO HINT OF ANY WARM LAYER. BEHIND THIS WAVE THE UPPER LEVEL TROF WILL AMPLIFY OVER THE NORTHEAST MAKING FOR A COLD WEEKEND WITH SCATTERED SNOW SHOWERS IN NORTH/NORTHWEST FLOW. BY SUNDAY/MONDAY, UPPER LEVEL HEIGHTS RISE WITH THE AIRMASS EXPECTED TO MODIFY UNDER SOUTHWEST FLOW. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... 630 AM UPDATE... A COLD WNW FLOW WILL CONTINUE TO GENERATE LAKE EFFECT SNOW. TWO BANDS AFFECTING ALL SITES. THE STRONGER, A SINGLE BAND OF LAKE EFFECT OFF OF LAKE ONTARIO WILL AFFECT ROME ALL MORNING INTO THE AFTN. RME WILL HAVE IFR CONDITIONS AND ALTERNATE MINIMUM. THE BAND WILL DROP FURTHER SOUTH TO SYR MIDDAY AGAIN WITH IFR CONDITIONS AND BELOW ALTERNATE MINIMUM. THIS WILL LAST THERE INTO THE EVENING. THE SECOND BAND OFF OF LAKE ERIE IS NOT AS INTENSE AND NOT CONTINUOUS. THIS HAS BEEN WAVERING ACROSS THE TWIN TIERS AND AFFECTING MOSTLY ELM OF LATE BUT HAS GOTTEN AVP BGM ITH TOO. AGAIN SOME IFR VSBYS BUT NOT SURE IF IT WILL CONTINUE AT THIS RATE. MODEL FORECASTS ONLY SHOW WEAK LAKE EFFECT BUT HAVE UNDERDONE EARLY THIS MORNING. FOR THIS PACKAGE ISSUED ONLY PUT A TEMPO FOR MVFR AT ELM. WEST WINDS AROUND 10 KTS EARLY THIS MORNING. INCREASING TO 10 TO 15 KTS WITH GUSTS TO 25 KTS BY 15Z CONTINUING UNTIL 23Z. WINDS DROPPING TO 10 KTS AT 23Z. .OUTLOOK... WED...MVFR/IFR IN SNOW SHOWERS FOR KRME/KSYR OTHERWISE PRIMARILY VFR. THURSDAY/THURSDAY NIGHT...PRIMARILY VFR. FRI... IFR CONDITIONS POSSIBLE IN SNOW. FRIDAY NIGHT/SATURDAY...MVFR SNOW SHOWERS RESTRICTIONS LIKELY FOR CENTRAL NY. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EST WEDNESDAY FOR NYZ009-036-037-045-046-057-062. LAKE EFFECT SNOW WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST WEDNESDAY FOR NYZ018-036-037. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST WEDNESDAY FOR NYZ009. && $$ SYNOPSIS...PVN NEAR TERM...PVN SHORT TERM...PVN LONG TERM...RRM/TAC AVIATION...TAC
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
144 AM EST TUE JAN 22 2013 .SYNOPSIS... PERIODS OF LIGHT SNOW WILL CONTINUE OFF AND ON OVERNIGHT TONIGHT. COLDER AIR WILL ARRIVE ON GUSTY WEST TO NORTHWEST WINDS LATER TONIGHT...WHICH WILL ALLOW LAKE EFFECT SNOWS TO DEVELOP. THIS ACTIVITY WILL DIMINISH ON THURSDAY AS HIGH PRESSURE BRIEFLY MOVES INTO THE AREA. OUTSIDE OF THE LAKE EFFECT SNOW...PARTLY TO MOSTLY CLOUDY SKIES AND SCATTERED SNOW SHOWERS OR FLURRIES ARE EXPECTED. && .NEAR TERM /THROUGH TODAY/... 1220 AM UPDATE... QUICK UPDATE TO GRIDS TO ACCNT FOR MODERATE TO HVY SNOW OVR NRN ONONDAGA CNTY WITH 1-2.5 INCH PER HR AMNTS. THANKFULLY THIS SNOW IS MVG QUICKLY INTO ONEIDA CNTY ATTM, THUS NO CHGS TO HEADLINES NEEDED. ANOTHER BATCH OF SNOW IS MVG THRU THE TWIN TIERS DUE TO LES OFF OF LK ERIE. EXPECT THIS TO CONTINUE FOR THE NEXT 1-2 HRS AND HV INCRSD POPS TO LKLY TO ACCNT FOR THIS ACTIVITY AS IT HEADS EAST. EXPECTING A QUICK HALF INCH TO ONE INCH OF SNOW WITH THESE SNOW SHOWERS AS THEY PASS THRU THE REGION. 1020 PM UPDATE... LATEST HIGH-RES MODELS CONTINUE TO ADVERTISE LAKE BAND DEVELOPMENT EAST OF LAKE ONTARIO THIS EVENING WITH RECENT RADAR TRENDS FROM BOTH KBUF AND KTYX NOW SHOWING THE INITIAL STAGES OF BAND DEVELOPMENT. THAT SAID...WE HAVE ELECTED TO EXTEND THE LAKE EFFECT SNOW WARNING SOUTH TO INCLUDE ALL ONEIDA COUNTY BEGINNING AT 06Z THIS EVENING. CONSIDERING THE BANDS ARE FORECAST BY HIGH-RES MODELS TO EXTEND SOUTH INTO ONONDAGA AND MADISON COUNTIES...HAVE POSTED A LAKE EFFECT SNOW WATCH FOR ZONES BEGINNING AT 15Z TUE WHERE 5 TO 9 INCHES OF NEW SNOW WILL BE POSSIBLE THROUGH TUE NIGHT. AS STATED IN THE PREVIOUS UPDATE...MODELS CONTINUE TO SHOW A FAIR AMOUNT OF BAND MOVEMENT DURING THE DAYLIGHT HOURS WHICH MAY BE A MANIFESTATION OF CONVECTIVE OVERTURNING DUE TO A STRONGLY UNSTABLE MIXED LAYER. ONCE THE BAND DOES FORM...WE EXPECT THE FEATURE TO BE FAIRLY INTENSE WITH HOURLY SNOWFALL RATES OF 1-2"/HR DEFINITELY A POSSIBILITY CONSIDERING HIGH INVERSION LEVELS (>14 KFT) AND STRONG INSTABILITY. ELSEWHERE...EVERYTHING REMAINS ON TRACK AND NO MAJOR ADJUSTMENTS ARE NEEDED AT THIS TIME. 820 PM UPDATE... EARLIER SNOWS THAT WARRANTED THE ISSUANCE OF A QUICK WINTER WX ADVISORY HAVE PUSHED EAST AND CONTINUE TO EXIT THE FORECAST AREA STAGE RIGHT. UPSTREAM RADAR TRENDS FROM KBUF CONTINUE TO SHOW A HEALTHY LAKE ERIE BAND WHICH HAS LED TO OVER A FOOT OF SNOW IN LESS THAN 4 HOURS ACROSS PORTIONS OF CHAUTAUQUA COUNTY EARLIER THIS EVENING. FORTUNATELY...THIS BAND WILL ONLY IMPACT PORTIONS OF STEUBEN AND YATES COUNTIES WITH ACCUMULATIONS ACROSS THESE AREAS LIKELY REMAINING BELOW ADVISORY THRESHOLDS. MAIN CONCERN THROUGH THE REMAINDER OF THE OVERNIGHT CONTINUES TO BE DEVELOPING LAKE SNOWS EAST OF LAKE ONTARIO AND POTENTIAL IMPACTS ACROSS PORTIONS OF ONEIDA COUNTY. LATEST HIGH-RES MODEL SUITE CONTINUES TO SHOW SOLID BAND ORGANIZATION AFTER THE 06Z TIME FRAME AS WESTERLY FLOW BECOMES ALIGNED WITH THE LONG AXIS OF LAKE ONTARIO. QUICK LOOK AT THE MOST RECENT 00Z BUF SOUNDING REVEALS MIXED LAYER HEIGHTS UP TO ROUGHLY 14 KFT WITH MANUAL SKEW-T ADJUSTMENTS FOR CURRENT LAKE TEMPS YIELDING CAPE VALUES IN EXCESS OF 500 J/KG. THIS COMBINED 850-MB TEMPS NEAR OF NEAR -20C WILL SET THE STAGE FOR WHAT SHOULD BE A BONAFIDE SINGLE LAKE EFFECT BAND THROUGH THE EARLY MORNING WITH THIS FEATURE THEN PERSISTING FOR MUCH OF THE DAY ON TUESDAY. MAIN QUESTION CONTINUES TO BE JUST HOW FAR SOUTH THIS BAND WILL GO AS CURRENT HIGH-RES MODELS SUGGEST BAND WILL OSCILLATE QUITE A BIT THROUGH THE DAY WHICH MAY BE A RESULT OF EXTREME INSTABILITY IN THE MIXED LAYER AND POTENTIAL CONVECTIVE OVERTURNING. THIS RAISES OUR SUSPICIONS THAT SOUTHERN ONEIDA COUNTY MAY ALSO GET A FAIRLY HEALTHY DOSE OF FRESH SNOW AS THE EVENT PROGRESSES AND FUTURE FORECAST UPDATES MAY HAVE TO CONSIDER A SOUTHWARD EXTENSION TO THE CURRENT LAKE EFFECT SNOW WARNING. ELSEWHERE TONIGHT...EXPECT PASSING LIGHT SNOW SHOWERS FROM TIME TO TIME WITH LITTLE TO NO ADDITIONAL ACCUMULATIONS ACROSS THE FINGER LAKES AND POINTS SOUTH. TEMPS WILL CONTINUE TO FALL INTO THE LOWER TO MIDDLE TEENS FOR OVERNIGHT LOWS. 450 PM UPDATE... HAVE HOISTED A QUICK WINTER WX ADVISORY FROM THE CENTRAL SOUTHERN TIER NORTHEAST THROUGH THE FINGER LAKES AND UPPER SUSQUEHANNA VALLEY REGIONS AS A NOTABLE LOW-LEVEL CONVERGENT SIGNATURE AS NOTED IN THE LATEST MSLP FIELD IS LEADING TO AN IMPRESSIVE LINEAR SNOW BAND. HAVE RECEIVED MULTIPLE 3 TO 5 INCH REPORTS ACROSS THE CENTRAL FINGER LAKES REGION AND BASED ON LATEST RR FORECASTS FROM THE SPC MESO PAGE...WE EXPECT THIS LOW-LEVEL CONVERGENCE REGION TO REMAIN IN PLACE FOR A FEW MORE HRS BEFORE FINALLY WINDING DOWN AFTER 00Z. BASED ON THIS...HAVE INCREASED SNOWFALL TOTALS ACROSS THE REGION WITH 4 TO 6 INCHES POSSIBLE FOR AREAS IN CLOSE PROXIMITY TO THE LOW-LEVEL CONVERGENT MAXIMUM. NO OTHER CHANGES NEEDED AT THIS TIME. PREVIOUS NEAR TERM DISCUSSION... FCST AREA WILL REMAIN UNDER NW FLOW ALOFT WITH A FEW EMBEDDED S/WV`S TRAVERSING THE RGN. 1ST ONE IS CRNTLY AFFECTING THE FCST AREA WITH AREAS OF LGT SNOW...AND 2ND ONE IS FCST TO MOVE INTO THE RGN ON WED NGT. A MEANDERING FNTL BNDRY AND LES INFLUENCES WILL CONTINUE TO MODULATE THE SHSN ACTIVITY ACRS THE FCST AREA INTO MID WEEK. LATER TNGT AS THE 1ST WAVE DEPARTS...LOW LVL FLOW WILL BCM WRLY AND FOCUS LES EFFECTS INTO NRN ONEIDA COUNTY AS 850 TEMPS DROPS TO ARND -20C. LOW LVL 270 FLOW BCMS ALIGNED BY 06Z. HIGH INVERSION LVL (10K FT)...ALIGNED FLOW AND GOOD SNOW GROWTH PROFILE. CRNT FCST HAS ACCUMS OF 6-10 INCHES PRIMARILY NEAR THE OSWEGO/LEWIS COUNTY BORDER. BOTTOM LINE IS THAT SRN PERIPHERY OF THIS BAND IS XPCTD TO BE OVER NRN ONEIDA WITH LOW END WARNING ACCUMS. THIS BAND IS FCST TO DROP SWD LATE TUE AFTN INTO NRN ONON/MAD/SRN ONEIDA/NRN OTSEGO. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... LES BAND XPCTD TO MEANDER ACRS FAVORED 290-300 FLOW REGIONS INTO WED MRNG...WHICH MAY BE ENHANCED BY LOW LVL CONVERGENCE ASSCD WITH SAGGING ARCTIC BNDRY. THIS ACTIVITY SHUD WEAKEN BY WED AFTN. PROFILES STILL LOOKING GOOD DURING THIS TIME FRAME...AS INVERSION LVL REMAINS HIGH AT 9-10 K FT AND LOW LVL FLOW REMAINS ALIGNED ARND 300 DEG...THEN THE INVERSION LOWERS AND FLOW WEAKENS BY WED AFTN. INITIAL THOUGHTS ARE THAT WE`LL NEED LES ADVISORIES FOR THIS TIME PERIOD. WE`LL DEFER ON THE POTNL HEADLINES ATTM...AND LET THE EVNG/MID SHIFTS RE-ASSESS. HAVE MENTIONED POTNL IN THE UPDATED HWO. OUTSIDE THE MAIN LES AREAS...SLGT CHC TO LOW CHC POPS...WITH POTNL FOR LAKE ERIE ACTIVITY TO CUT ACRS PORTIONS OF THE SRN TIER AND NE PA. CONCERNING WIND CHILLS...GIVEN CRNT FCST TEMPS AND WINDS WE DO NOT SHOW ANY VALUES BLO -15 UNTIL TMRW NGT ACRS ONEIDA COUNTY. PSBL THAT A FEW OTHER LOCATIONS COULD APRCH VALUES. LATER SHIFTS CAN RE-EVALUATE THIS. ON WED XPCT LES ACTIVITY TO DIMINISH BUT APRCHNG S/WV COULD RESULT IN DVLPMNT OF MORE --SHSN AS THE DAY PROGRESSES SO WE CONTINUE WITH CHC POPS MOST LOCATIONS. BEST CHC FOR A DRY DAY WILL BE THURSDAY AS SFC HIGH IS XPCTD TO CREST OVER THE RGN LATE IN THE DAY. && .LONG TERM /FRIDAY THROUGH MONDAY/... MODELS SIMILAR. GRIDS LOOK GOOD. LITTLE CHANGE. PREVIOUS DISCUSSION... MEDIUM RANGE MODELS ARE IN FAIR AGREEMENT THROUGH THE EXTENDED. INITIALLY A SOUTHERN STREAM SYSTEM WILL TRACK THROUGH THE MID ATLANTIC REGION ON FRIDAY. THE ECMWF/CANADIAN IS MUCH FASTER THAN THE GFS, LEANED TOWARD THE ECMWF ENSEMBLE WHICH IS A GOOD COMPROMISE. THURSDAY NIGHT BACKED OFF ON POPS TO JUST CHC THEN CHC/LIKELY ON FRIDAY WITH LIKELY POPS ACROSS THE SOUTHERN TIER AND NE PA. MODELS INDICATE ALL SNOW WITH NO HINT OF ANY WARM LAYER. BEHIND THIS WAVE THE UPPER LEVEL TROF WILL AMPLIFY OVER THE NORTHEAST MAKING FOR A COLD WEEKEND WITH SCATTERED SNOW SHOWERS IN NORTH/NORTHWEST FLOW. BY SUNDAY/MONDAY, UPPER LEVEL HEIGHTS RISE WITH THE AIRMASS EXPECTED TO MODIFY UNDER SOUTHWEST FLOW. && .AVIATION /07Z TUESDAY THROUGH SATURDAY/... 1230 AM UPDATE... A SHORTWAVE GOING THROUGH NOW HAS PUSHED IFR SNOW SHOWERS THROUGH BGM ITH AND SYR. THESE HAVE ENDED THERE. RME WILL HAVE IFR VSBYS AND MAYBE CIGS FOR AN HOUR OR TWO BEFORE LIFTING NORTH OF THEM. A SINGLE BAND OF LAKE EFFECT OFF OF LAKE ONTARIO WILL SET UP IN OSWEGO AND LEWIS COUNTIES. THIS BAND WILL DROP SOUTH INTO RME AROUND 12Z AND REMAIN MOST OF THE DAY. RME WILL HAVE IFR CONDITIONS AND ALTERNATE MINIMUM. THE BAND WILL DROP FURTHER SOUTH TO SYR MIDDAY AGAIN WITH IFR CONDITIONS AND BELOW ALTERNATE MINIMUM. WITH THIS WSW FLOW THE REST OF THE TAF SITES SHOULD BE MOSTLY VFR AND FAR ENOUGH AWAY FROM LAKE ERIE TO CAUSE REDUCTIONS. EXCEPTION IS KAVP AS THE SNOW THAT WENT THROUGH ITH AND BGM DROPS SOUTH. SOME MVFR POSSIBLE THERE 8 TO 12Z. WEST WINDS AROUND 10 KTS EARLY THIS MORNING. INCREASING TO 10 TO 15 KTS WITH GUSTS TO 25 KTS DURING THE DAY. WINDS DROPPING TO 10 KTS AT 23Z. .OUTLOOK... TUE NIGHT THRU WED...MVFR/IFR IN SNOW SHOWERS FOR KRME/KSYR OTHERWISE PRIMARILY VFR. THURSDAY/THURSDAY NIGHT...PRIMARILY VFR. FRI... IFR CONDITIONS POSSIBLE IN SNOW. FRIDAY NIGHT/SATURDAY...MVFR SNOW SHOWERS RESTRICTIONS LIKELY FOR CENTRAL NY. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...LAKE EFFECT SNOW WATCH FROM 10 AM EST THIS MORNING THROUGH WEDNESDAY MORNING FOR NYZ018-036. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST WEDNESDAY FOR NYZ009- 037. && $$ SYNOPSIS... NEAR TERM...CMG/PVN SHORT TERM... LONG TERM...RRM/TAC AVIATION...TAC
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1226 AM EST TUE JAN 22 2013 .SYNOPSIS... PERIODS OF LIGHT SNOW WILL CONTINUE OFF AND ON OVERNIGHT TONIGHT. COLDER AIR WILL ARRIVE ON GUSTY WEST TO NORTHWEST WINDS LATER TONIGHT...WHICH WILL ALLOW LAKE EFFECT SNOWS TO DEVELOP. THIS ACTIVITY WILL DIMINISH ON THURSDAY AS HIGH PRESSURE BRIEFLY MOVES INTO THE AREA. OUTSIDE OF THE LAKE EFFECT SNOW...PARTLY TO MOSTLY CLOUDY SKIES AND SCATTERED SNOW SHOWERS OR FLURRIES ARE EXPECTED. && .NEAR TERM /THROUGH TODAY/... 1220 AM UPDATE... QUICK UPDATE TO GRIDS TO ACCNT FOR MODERATE TO HVY SNOW OVR NRN ONONDAGA CNTY WITH 1-2.5 INCH PER HR AMNTS. THANKFULLY THIS SNOW IS MVG QUICKLY INTO ONEIDA CNTY ATTM, THUS NO CHGS TO HEADLINES NEEDED. ANOTHER BATCH OF SNOW IS MVG THRU THE TWIN TIERS DUE TO LES OFF OF LK ERIE. EXPECT THIS TO CONTINUE FOR THE NEXT 1-2 HRS AND HV INCRSD POPS TO LKLY TO ACCNT FOR THIS ACTIVITY AS IT HEADS EAST. EXPECTING A QUICK HALF INCH TO ONE INCH OF SNOW WITH THESE SNOW SHOWERS AS THEY PASS THRU THE REGION. 1020 PM UPDATE... LATEST HIGH-RES MODELS CONTINUE TO ADVERTISE LAKE BAND DEVELOPMENT EAST OF LAKE ONTARIO THIS EVENING WITH RECENT RADAR TRENDS FROM BOTH KBUF AND KTYX NOW SHOWING THE INITIAL STAGES OF BAND DEVELOPMENT. THAT SAID...WE HAVE ELECTED TO EXTEND THE LAKE EFFECT SNOW WARNING SOUTH TO INCLUDE ALL ONEIDA COUNTY BEGINNING AT 06Z THIS EVENING. CONSIDERING THE BANDS ARE FORECAST BY HIGH-RES MODELS TO EXTEND SOUTH INTO ONONDAGA AND MADISON COUNTIES...HAVE POSTED A LAKE EFFECT SNOW WATCH FOR ZONES BEGINNING AT 15Z TUE WHERE 5 TO 9 INCHES OF NEW SNOW WILL BE POSSIBLE THROUGH TUE NIGHT. AS STATED IN THE PREVIOUS UPDATE...MODELS CONTINUE TO SHOW A FAIR AMOUNT OF BAND MOVEMENT DURING THE DAYLIGHT HOURS WHICH MAY BE A MANIFESTATION OF CONVECTIVE OVERTURNING DUE TO A STRONGLY UNSTABLE MIXED LAYER. ONCE THE BAND DOES FORM...WE EXPECT THE FEATURE TO BE FAIRLY INTENSE WITH HOURLY SNOWFALL RATES OF 1-2"/HR DEFINITELY A POSSIBILITY CONSIDERING HIGH INVERSION LEVELS (>14 KFT) AND STRONG INSTABILITY. ELSEWHERE...EVERYTHING REMAINS ON TRACK AND NO MAJOR ADJUSTMENTS ARE NEEDED AT THIS TIME. 820 PM UPDATE... EARLIER SNOWS THAT WARRANTED THE ISSUANCE OF A QUICK WINTER WX ADVISORY HAVE PUSHED EAST AND CONTINUE TO EXIT THE FORECAST AREA STAGE RIGHT. UPSTREAM RADAR TRENDS FROM KBUF CONTINUE TO SHOW A HEALTHY LAKE ERIE BAND WHICH HAS LED TO OVER A FOOT OF SNOW IN LESS THAN 4 HOURS ACROSS PORTIONS OF CHAUTAUQUA COUNTY EARLIER THIS EVENING. FORTUNATELY...THIS BAND WILL ONLY IMPACT PORTIONS OF STEUBEN AND YATES COUNTIES WITH ACCUMULATIONS ACROSS THESE AREAS LIKELY REMAINING BELOW ADVISORY THRESHOLDS. MAIN CONCERN THROUGH THE REMAINDER OF THE OVERNIGHT CONTINUES TO BE DEVELOPING LAKE SNOWS EAST OF LAKE ONTARIO AND POTENTIAL IMPACTS ACROSS PORTIONS OF ONEIDA COUNTY. LATEST HIGH-RES MODEL SUITE CONTINUES TO SHOW SOLID BAND ORGANIZATION AFTER THE 06Z TIME FRAME AS WESTERLY FLOW BECOMES ALIGNED WITH THE LONG AXIS OF LAKE ONTARIO. QUICK LOOK AT THE MOST RECENT 00Z BUF SOUNDING REVEALS MIXED LAYER HEIGHTS UP TO ROUGHLY 14 KFT WITH MANUAL SKEW-T ADJUSTMENTS FOR CURRENT LAKE TEMPS YIELDING CAPE VALUES IN EXCESS OF 500 J/KG. THIS COMBINED 850-MB TEMPS NEAR OF NEAR -20C WILL SET THE STAGE FOR WHAT SHOULD BE A BONAFIDE SINGLE LAKE EFFECT BAND THROUGH THE EARLY MORNING WITH THIS FEATURE THEN PERSISTING FOR MUCH OF THE DAY ON TUESDAY. MAIN QUESTION CONTINUES TO BE JUST HOW FAR SOUTH THIS BAND WILL GO AS CURRENT HIGH-RES MODELS SUGGEST BAND WILL OSCILLATE QUITE A BIT THROUGH THE DAY WHICH MAY BE A RESULT OF EXTREME INSTABILITY IN THE MIXED LAYER AND POTENTIAL CONVECTIVE OVERTURNING. THIS RAISES OUR SUSPICIONS THAT SOUTHERN ONEIDA COUNTY MAY ALSO GET A FAIRLY HEALTHY DOSE OF FRESH SNOW AS THE EVENT PROGRESSES AND FUTURE FORECAST UPDATES MAY HAVE TO CONSIDER A SOUTHWARD EXTENSION TO THE CURRENT LAKE EFFECT SNOW WARNING. ELSEWHERE TONIGHT...EXPECT PASSING LIGHT SNOW SHOWERS FROM TIME TO TIME WITH LITTLE TO NO ADDITIONAL ACCUMULATIONS ACROSS THE FINGER LAKES AND POINTS SOUTH. TEMPS WILL CONTINUE TO FALL INTO THE LOWER TO MIDDLE TEENS FOR OVERNIGHT LOWS. 450 PM UPDATE... HAVE HOISTED A QUICK WINTER WX ADVISORY FROM THE CENTRAL SOUTHERN TIER NORTHEAST THROUGH THE FINGER LAKES AND UPPER SUSQUEHANNA VALLEY REGIONS AS A NOTABLE LOW-LEVEL CONVERGENT SIGNATURE AS NOTED IN THE LATEST MSLP FIELD IS LEADING TO AN IMPRESSIVE LINEAR SNOW BAND. HAVE RECEIVED MULTIPLE 3 TO 5 INCH REPORTS ACROSS THE CENTRAL FINGER LAKES REGION AND BASED ON LATEST RR FORECASTS FROM THE SPC MESO PAGE...WE EXPECT THIS LOW-LEVEL CONVERGENCE REGION TO REMAIN IN PLACE FOR A FEW MORE HRS BEFORE FINALLY WINDING DOWN AFTER 00Z. BASED ON THIS...HAVE INCREASED SNOWFALL TOTALS ACROSS THE REGION WITH 4 TO 6 INCHES POSSIBLE FOR AREAS IN CLOSE PROXIMITY TO THE LOW-LEVEL CONVERGENT MAXIMUM. NO OTHER CHANGES NEEDED AT THIS TIME. PREVIOUS NEAR TERM DISCUSSION... FCST AREA WILL REMAIN UNDER NW FLOW ALOFT WITH A FEW EMBEDDED S/WV`S TRAVERSING THE RGN. 1ST ONE IS CRNTLY AFFECTING THE FCST AREA WITH AREAS OF LGT SNOW...AND 2ND ONE IS FCST TO MOVE INTO THE RGN ON WED NGT. A MEANDERING FNTL BNDRY AND LES INFLUENCES WILL CONTINUE TO MODULATE THE SHSN ACTIVITY ACRS THE FCST AREA INTO MID WEEK. LATER TNGT AS THE 1ST WAVE DEPARTS...LOW LVL FLOW WILL BCM WRLY AND FOCUS LES EFFECTS INTO NRN ONEIDA COUNTY AS 850 TEMPS DROPS TO ARND -20C. LOW LVL 270 FLOW BCMS ALIGNED BY 06Z. HIGH INVERSION LVL (10K FT)...ALIGNED FLOW AND GOOD SNOW GROWTH PROFILE. CRNT FCST HAS ACCUMS OF 6-10 INCHES PRIMARILY NEAR THE OSWEGO/LEWIS COUNTY BORDER. BOTTOM LINE IS THAT SRN PERIPHERY OF THIS BAND IS XPCTD TO BE OVER NRN ONEIDA WITH LOW END WARNING ACCUMS. THIS BAND IS FCST TO DROP SWD LATE TUE AFTN INTO NRN ONON/MAD/SRN ONEIDA/NRN OTSEGO. && .SHORT TERM /TONIGHT THROUGH THURSDAY/... LES BAND XPCTD TO MEANDER ACRS FAVORED 290-300 FLOW REGIONS INTO WED MRNG...WHICH MAY BE ENHANCED BY LOW LVL CONVERGENCE ASSCD WITH SAGGING ARCTIC BNDRY. THIS ACTIVITY SHUD WEAKEN BY WED AFTN. PROFILES STILL LOOKING GOOD DURING THIS TIME FRAME...AS INVERSION LVL REMAINS HIGH AT 9-10 K FT AND LOW LVL FLOW REMAINS ALIGNED ARND 300 DEG...THEN THE INVERSION LOWERS AND FLOW WEAKENS BY WED AFTN. INITIAL THOUGHTS ARE THAT WE`LL NEED LES ADVISORIES FOR THIS TIME PERIOD. WE`LL DEFER ON THE POTNL HEADLINES ATTM...AND LET THE EVNG/MID SHIFTS RE-ASSESS. HAVE MENTIONED POTNL IN THE UPDATED HWO. OUTSIDE THE MAIN LES AREAS...SLGT CHC TO LOW CHC POPS...WITH POTNL FOR LAKE ERIE ACTIVITY TO CUT ACRS PORTIONS OF THE SRN TIER AND NE PA. CONCERNING WIND CHILLS...GIVEN CRNT FCST TEMPS AND WINDS WE DO NOT SHOW ANY VALUES BLO -15 UNTIL TMRW NGT ACRS ONEIDA COUNTY. PSBL THAT A FEW OTHER LOCATIONS COULD APRCH VALUES. LATER SHIFTS CAN RE-EVALUATE THIS. ON WED XPCT LES ACTIVITY TO DIMINISH BUT APRCHNG S/WV COULD RESULT IN DVLPMNT OF MORE --SHSN AS THE DAY PROGRESSES SO WE CONTINUE WITH CHC POPS MOST LOCATIONS. BEST CHC FOR A DRY DAY WILL BE THURSDAY AS SFC HIGH IS XPCTD TO CREST OVER THE RGN LATE IN THE DAY. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... MEDIUM RANGE MODELS ARE IN FAIR AGREEMENT THROUGH THE EXTENDED. INITIALLY A SOUTHERN STREAM SYSTEM WILL TRACK THROUGH THE MID ATLANTIC REGION ON FRIDAY. THE ECMWF/CANADIAN IS MUCH FASTER THAN THE GFS, LEANED TOWARD THE ECMWF ENSEMBLE WHICH IS A GOOD COMPROMISE. THURSDAY NIGHT BACKED OFF ON POPS TO JUST CHC THEN CHC/LIKELY ON FRIDAY WITH LIKELY POPS ACROSS THE SOUTHERN TIER AND NE PA. MODELS INDICATE ALL SNOW WITH NO HINT OF ANY WARM LAYER. BEHIND THIS WAVE THE UPPER LEVEL TROF WILL AMPLIFY OVER THE NORTHEAST MAKING FOR A COLD WEEKEND WITH SCATTERED SNOW SHOWERS IN NORTH/NORTHWEST FLOW. BY SUNDAY/MONDAY, UPPER LEVEL HEIGHTS RISE WITH THE AIRMASS EXPECTED TO MODIFY UNDER SOUTHWEST FLOW. && .AVIATION /05Z TUESDAY THROUGH SATURDAY/... AN UPPER LEVEL DISTURBANCE AND ITS ASSOCIATED WEAK SFC FEATURE WILL TRACK ACROSS CENTRAL PA LATE THIS AFTERNOON THROUGH THE EARLY EVENING. THIS SYSTEM WILL PRODUCE WIDESPREAD MVFR CONDITIONS IN LIGHT SNOW ACROSS ALL OF THE TERMINALS THIS AFTERNOON THROUGH THE EARLY EVENING PERIOD. ACROSS THE SOUTHERN TERMINALS IFR CONDITIONS ARE POSSIBLE BETWEEN 18Z-00Z, BUT MOST LIKELY AT KBGM/KAVP. BEHIND THIS WAVE NORTHWEST FLOW WILL DEVELOP KEEPING PRIMARILY MVFR CONDITIONS ACROSS THE REGION THROUGH 06Z WITH SCATTERED FLURRIES AND SNOW SHOWERS. AFTER 06Z CONDITIONS WILL BE PRIMARILY VFR WITH SOUTHWEST WINDS DEVELOPING. THE LAKE EFFECT SNOW IS EXPECTED TO REMAIN NORTH OF THE KRME/KSYR TERMINALS THROUGH 18Z BUT AFTER 18Z IT IS EXPECTED TO AFFECT THE AIRPORTS WITH IFR CONDITIONS LIKELY. SOUTHWEST WINDS AROUND 5 KNOTS OT LIGHT AND VARIABLE BECOMING NORTHWEST THIS EVENING AROUND 10 KNOTS SHIFTING TO THE SOUTHWEST TOWARD DAYBREAK AND INCREASING TO 12-15 KNOTS WITH GUSTS AROUND 25 KNOTS. .OUTLOOK... TUE NIGHT THRU WED...MVFR/IFR IN SNOW SHOWERS FOR KRME/KSYR OTHERWISE PRIMARILY VFR. THURSDAY/THURSDAY NIGHT...PRIMARILY VFR. FRI... IFR CONDITIONS POSSIBLE IN SNOW. FRIDAY NIGHT/SATURDAY...MVFR SNOW SHOWERS RESTRICTIONS LIKELY FOR CENTRAL NY. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...LAKE EFFECT SNOW WATCH FROM 10 AM EST THIS MORNING THROUGH WEDNESDAY MORNING FOR NYZ018-036. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST WEDNESDAY FOR NYZ009- 037. && $$ SYNOPSIS...PVN NEAR TERM...CMG/PVN SHORT TERM... LONG TERM...RRM AVIATION...MLJ/RRM
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1212 AM EST TUE JAN 22 2013 .SYNOPSIS... ARCTIC AIR WILL POUR INTO CENTRAL PENNSYLVANIA TONIGHT BEHIND A CLIPPER SYSTEM...PRODUCING SCATTERED TO NUMEROUS SNOW SHOWERS AND A FEW SQUALLS. LAKE EFFECT SNOW WILL PRODUCE SEVERAL INCHES OF ACCUMULATION OVER THE FAR NORTHWEST...WHILE WIND CHILLS WILL DROP BELOW 15 BELOW ZERO OVER THE LAUREL HIGHLANDS LATER TONIGHT. THE SURGE OF ARCTIC AIR WILL LAST THROUGH MID WEEK. LAKE EFFECT SNOW SHOWERS WILL CONTINUE INTO TUESDAY EVENING BEFORE DECREASING. A LOW PRESSURE SYSTEM WILL TRACK FROM THE SOUTHERN PLAINS TO THE MID ATLANTIC COAST LATE IN THE WEEK BRINGING A CHANCE OF SNOW TO MOST OF THE AREA. && .NEAR TERM /UNTIL 8 AM TUESDAY MORNING/... BIG OL LES BAND PARALLEL TO THE LAKE SHORE LINE IS BREAKING UP AS THE FLOW IN THE LOWEST 5-10KFT BECOMES MORE NWRLY. THE PROGS FROM THE NAM/RUC AND HRRR STILL POINT TO THIS BAND/AREA CONTINUING TO SLIDE ESE AND PIVOT TO BE MORE WEST-EAST BEFORE FIZZLING AS IT NEARS I-80. THE TRANSITORY NATURE SHOULD KEEP ACCUMS IN THE RANGE WE HAVE GOING. FETCH IS ALL VERY FAVORABLE FOR SNOW TO PILE UP OVER WARREN COUNTY AND ALSO ACCUMULATE ACROSS THE REST OF THE NW/NRN MTS. CONSIDERED A BUMP TO LES WARNING FOR WARREN COUNTY /AND PERHAPS ADVY IN MCKEAN CO/ WITH SOME HIGHER THAN 8 INCH ACCUMS POSS IN THE NW SNOW BELT AND N OF ROUTE 6. BUT DECIDED TO HOLD THE COURSE SINCE THERE HAS BEEN LITTLE SNOW IN WARREN COUNTY THROUGH THE DAY. NEW NAM AND OTHER MESO MDLS ALSO HOLD NO BIG REVELATIONS. THE UPSLOPE FLOW IS ABOUT THE ONLY THING GOING FOR SNOW ACCUMS IN THE LAURELS. LOTS OF LARGE BREAKS IN THE CLOUDS NOW...BUT IT TOO SHOULD TREND TOWARD A CLIMO LOOK AS THE FLOW BECOMES WNW. THE ARCTIC AIR HAS ALREADY BROUGHT TEMPS DOWN TO 10F IN THE WRN MTS...AND WIND CHILLS ARE BELOW ZERO THERE AS WELL. WINDS JUST PICKED UP IN THE VALLEYS OF THE EAST...AND WILL STAY UP ALL NIGHT ACROSS THE AREA - WITH THE HIGHEST SPEEDS IN THE MTS. THUS...THE WIND CHILL ADVY IS SOLID...AND WILL REMAIN. SPOTTY -15F WIND CHILLS MAY BE HAD IN THE NRN MTS...BUT CLOUDS AND SLIGHTLY LOWER WIND SPEEDS THERE SHOULD KEEP COUNTY-WIDE AREAS OF -15 FROM OCCURRING. THIS IS ALREADY THE COLDEST NIGHT OF THE SEASON FOR MOST OF PENNSYLVANIA. && .SHORT TERM /8 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... THE UPPER TROF SWINGS ACROSS PA TONIGHT AND EARLY TUESDAY. A WELL MIXED BLYR SHOULD ALLOW 25-30KT GUSTS TO MIX TO THE SFC TUESDAY...PERSISTING THROUGHOUT THE DAY WITH WIND CHILLS REMAINING BELOW ZERO FOR MUCH OF THE REGION. WIND CHILL ADVISORY WILL REMAIN IN EFFECT OVER THE LAURELS THROUGHOUT THE DAY. ENS MEAN 850MB TEMPS ARND -21C SHOULD TRANSLATE TO HIGHS ONLY NEAR 10F ACROSS THE ALLEGHENY MTNS AND AROUND 20F ACROSS THE SUSQ VALLEY. REGARDING LAKE EFFECT SNOW ADVISORY...BOUNDARY LAYER FLOW OF ARND 280 DEGREES WOULD PRECLUDE ANY HURON CONNECTION OR LONG FETCH WITH THE HEAVIEST BANDS AND ACCUMS STAYING JUST NORTH OF MY AREA. STILL...THE NEXT 24 HRS COULD HOLD 8 INCHES ACROSS NORTHWESTERN WARREN COUNTY. A SLIGHT SOUTHWARD SHIFT IN BANDS COULD ALWAYS OCCUR...AND WILL BE MONITORED. 20/1 RATIOS PRODUCE 6-8 INCHES OVER THE SNOWBELT OF NW WARREN COUNTY BTWN THIS AFTN AND TUE EVENING. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... SOME SNOW SHOWERS WILL BE ACROSS NORTHERN AND WESTERN AREAS TUE NIGHT AND WED...GIVEN NW FLOW OF COLD AIR. MODELS HINT THAT ACTIVITY COULD BE A LITTLE MORE ACTIVE ON WED...AS JET MAX MOVES ACROSS THE AREA. DID NOT RUSH TO TAPER ACTIVITY WED NIGHT...GIVEN HOW COLD THE AIRMASS IS. THU WILL BE THE BEST DAY. LEFT AMTS CLOSE TO WHAT WAS IN GRIDS FOR NEXT MODERATE SNOW EVENT. YESTERDAY...MODELS WERE A LITTLE FASTER WITH THE SYSTEM...TODAY THEY ARE SLOWER...SO MADE SOME TIMING ADJUSTMENTS. DID PUT SOME SLEET BACK IN...BUT JUST THE FAR SOUTH...GIVEN POTENTIAL FOR SOME MID LVL WARMING. SYSTEM DOES NOT HAVE A LOT OF GULF MOISTURE TO WORK WITH...BUT STRONG WARM ADVECTION MAY AID IN BRIEF HEAVIER BURST OF SNOW. MORE COLD AND SNOW SHOWERS FOR THE FIRST PART OF THE WEEKEND. TEMPS MODERATE SOME FOR LATER SUNDAY INTO MONDAY. SPEAKING OF TEMPS...COMBINATION OF WIND AND COLD SUPPORT WIND CHILLS IN THE ADVISORY RANGE. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... BANDS OF SNOW SHOWERS AND ACCOMPANYING GUSTY WINDS CONTINUE TO CAUSE MVFR/OCNL IFR CIGS AND VSBYS ACROSS THE NORTH EASTERN AREAS. BANDS OF HEAVIER SNOW SHOWERS AND A FEW SQUALLS WILL ACCOMPANY LOW PRESSURE AND ITS ASSOCIATED COLD FRONT MAINLY THROUGH THE NW MTNS. MUCH COLDER AIR WILL MOVE IN OVERNIGHT WITH /-20C AT 850MB/. MOISTURE AGAIN WILL BE LIMITED WHICH WILL KEEP CIG/VSBY REDUCTIONS AND SNOW IMPACTS CONFINED MAINLY TO HIGHER TERRAIN IN THE WEST. COLD FLOW ACROSS MUCH WARMER LAKES WILL BRING LOWER CLOUDS INTO KBFD-KJST STARTING LATE TUESDAY MORNING AND ENHANCE SNOW POTENTIAL IN THOSE SAME AREAS. BIGGEST SNOWFALL WILL BE CONFINED CLOSER TO LAKE ERIE...BUT LIGHTER INTERMITTANT BANDED SNOWS WILL IMPACT KBFD-KJST FOR NEXT COUPLE OF DAYS AS PERSISTENT NW FLOW ESTABLISHES ITSELF. OCNL ENCROACHMENT OF MVFR POSS INTO CENTRAL MTNS...WHILE DOWNSLOPE FLOW KEEPS WEATHER VFR IN THE EAST. WINDS WILL PICK BACK UP TODAY A BIT...ESPECIALLY OVER WESTERN HIGHER TERRAIN WHERE GUSTS TO 20-30 MPH WILL AGAIN BECOME COMMON. OUTLOOK... TUE-THU AM...SHSN WITH MVFR/OCNL IFR W MTNS...SCT/LIKELY SHSN IN MVFR CENTRAL MTNS...SCT SHSN AND PRIMARILY VFR SE. THU PM-FRI...MVFR/IFR POSSIBLE LATE. && .CTP WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST TUESDAY FOR PAZ004. WIND CHILL ADVISORY UNTIL 1 PM EST WEDNESDAY FOR PAZ024-033. && $$ SYNOPSIS...DEVOIR NEAR TERM...DANGELO SHORT TERM...DANGELO/DEVOIR LONG TERM...MARTIN AVIATION...DEVOIR/CERU
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
949 PM EST WED JAN 23 2013 .SYNOPSIS... COOL CANADIAN HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE REGION TONIGHT. THIS COLD AIRMASS WILL SLOWLY WARM...WHILE A WARM FRONT WORKS INTO THE REGION TOMORROW. A COLD FRONT WILL THEN CROSS THE AREA FRIDAY AND MIX IN SOME ARCTIC AIR OVER THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY/... AS OF 945 PM...THE 00Z NAM AND 21Z SREF HAVE BACKED OFF ON THE DEVELOPMENT OF PRECIP OVERNIGHT WITH THE WEAK CLIPPER SYSTEM MOVING THRU. THE LAST SEVERAL RAP RUNS HAVE BEEN DRY...BUT THE 17Z LOCAL WRF-ARW STILL HAVE SOME PRECIP...ALBEIT VERY LIGHT. THESE TRENDS APPEAR TO BE VALID AS SAT PIX ONLY NOW SHOWING SOME LOW CLOUDS FORMING TO OUR NW. THEREFORE...HAVE FOLLOWED THE TRENDS AND BACKED OFF ON PRECIP FROM THE WWA FORCING AHEAD OF THE SYSTEM...BUT KEEP PRECIP IN THE NW FLOW FORCING BEHIND THE SYSTEM. THIS MEANS ONLY A SMALL CHC OF VERY LIGHT FREEZING RAIN WITH SNOW BEING THE MAIN P-TYPE. IN ADDITION...WENT WITH THE P-TYPE NOMOGRAM METHOD OF CREATING WX GRIDS INSTEAD OF TOP DOWN. THE NOMOGRAM SEEMS TO CAPTURE THE PREVIOUS AND CURRENT THINKING OF FZRA TURNING TO SN BETTER THAN THE TOP DOWN WHICH KEEPS MORE WIDESPREAD FZRA IN LONGER. OF COURSE...GIVEN THE LACK OF PRECIP UPSTREAM...THIS COULD ALL JUST BE AN EXERCISE IN FUTILITY. HAVE BACKED OFF ON QPF AS WELL GIVEN THE LACK OF PRECIP UPSTREAM AND LATEST MDL GUIDANCE. THIS STILL GIVES A TRACE OF GLAZE IN THE HIGHEST ELEVATIONS AND A DUSTING OF SNOW. GIVEN THE OVERALL TRENDS AND LACK OF CONFIDENCE...IT STILL SEEMS AN ADV IS NOT WARRANTED. THEREFORE...WILL JUST LET THE FORECAST SPEAK FOR ITSELF WITH A BRIEF PERIOD OF POTENTIAL WINTRY PRECIP WITH LITTLE TO NO ACCUM. HAD TO DROP LOWS ACROSS MUCH OF THE AREA AS TEMPS WERE RUNNING COOLER THAN NORMAL. IT LOOKS LIKE WINDS ARE PICKING UP ACROSS THE NRN MTNS...SO THE WIND ADV STILL SEEMS WELL PLACED. AS OF 645 PM...18Z MDLS CONTINUE TO SHOW PREVIOUS TRENDS OF WWA FORCED PRECIP DEVELOPING ACROSS THE MTNS LATE THIS EVENING THEN BECOMING DOMINATED BY NW FLOW PROCESSES BY MORNING. THEREFORE...THE FCST POP AND P-TYPE TRENDS STILL LOOK GOOD. STILL EXPECT ONLY VERY LIGHT PRECIP AMOUNTS...SO NO WINTER WX ADV IS EXPECTED. MAIN UPDATES WERE FOR CURRENT CONDITIONS. PREVIOUS DISCUSSION...A SHORT WAVE TROUGH WILL DIG SOUTHEAST TOWARD THE OHIO VALLEY AND MID-ATLANTIC THIS EVENING...DEEPENING THE MEAN LONG WAVE TROUGH OVER THE EASTERN CONUS AND REINFORCING THE UNSEASONABLY COOL AIR MASS WITH ANOTHER (MOSTLY DRY) COLD FRONT. HOWEVER...A WAA PATTERN DEVELOPING ACROSS THE TENN VALLEY WILL RESULT IN SOME ENHANCED LOW LEVEL MOISTURE AHEAD OF THE FRONT. THIS WILL BE AUGMENTED ACROSS THE WESTERN MOUNTAINS BY A STRONG WESTERLY LOW LEVEL FLOW. THE FORCING TONIGHT WILL REMAIN WEAK...LIMITED TO WEAK WAA AND A BIT OF AN UPSLOPE COMPONENT ALONG THE SPINE OF THE APPALACHIANS...AND MOISTURE WILL BE SHALLOW. THEREFORE...POPS WILL GENERALLY BE CONFINED TO THE COUNTIES BORDERING TENN...AND WILL BE LIMITED TO THE 30-50 RANGE. P-TYPE IS SOMEWHAT PROBLEMATIC. TEMPS IN THE MOIST LAYER DO NOT FALL BELOW -8 C UNTIL COLD ADVECTION OVERTAKES THE AREA TOWARD 12Z. THIS DOES NOT ALWAYS TRANSLATE TO A LACK OF SNOW DURING NW FLOW EVENTS (MAINLY DUE TO THE CONVECTIVE NATURE OF THOSE EVENTS). HOWEVER...THE /WARM SIDE/ OF TONIGHT/S EVENT WILL NOT BE A TRUE NW FLOW REGIME... SO I THINK THIS IS A CASE IN WHICH -FZRA OR -FZDZ WILL BE THE PRIMARY P-TYPE...UNTIL THE COLD FRONT SWEEPS THROUGH THE AREA... AFTER WHICH WE WILL SEE A TRANSITION TO A BRIEF NW FLOW SNOW EVENT. PRECIP RATES AND BRIEF DURATION OF THE EVENT SHOULD RESULT IN VERY LIGHT ICE/SNOW ACCUMS. TRAVEL PROBLEMS COULD ARISE IF WE SEE A COUPLE OF HOURS OF FREEZING DRIZZLE...WHICH COULD POTENTIALLY MAKE THE ROADS A MESS IN AREAS RIGHT ALONG THE STATE LINE. THIS IS POSSIBLE...BUT I/M NOT CONFIDENT ENOUGH TO ISSUE ANY PRODUCTS ATTM. WE WILL CONTINUE TO MENTION THIS IN THE HWO. THE OTHER CONCERN WILL BE THE WIND...AS H8 WINDS TURN TOWARD THE NW TOWARD DAYBREAK AND STRENGTHEN IN THE STRONG COLD ADVECTION. WINDS AT THE TOP OF THE MIXED LAYER INCREASE TO 45-55 KT ACROSS MUCH OF THE MTNS AS A SURFACE LOW DEEPENS OFF THE NC COAST. HOWEVER...THE SURFACE GRADIENT ACROSS THE MTNS NEVER EXCEEDS 5 OR 6 MB. WHILE THIS DOES NOT FAVOR A HIGH WIND EVENT...A WIND ADVISORY SEEMS PRUDENT FOR THE NORTHERN MTNS AND HIGH ELEVATIONS OF THE NORTHERN FOOTHILLS LATE TONIGHT AND TOMORROW MORNING. INCREASING CLOUDS AND PERSISTENT MIXING WILL RESULT IN MIN TEMPS MUCH CLOSER TO NORMAL THAN WE HAVE SEEN THE PAST COUPLE OF MORNINGS. DESPITE CLEARING SKIES DURING THE AFTERNOON THURSDAY...MAX TEMPS WILL BE COOLER THAN TODAY/S READINGS (MUCH COOLER OVER THE MTNS) OWING TO THE RESURGENCE OF COLD AIR. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... AS OF MIDDAY WED...NOT MUCH GOING ON IN THE UPPER ATMOSPHERE TO START THE PERIOD AT 00Z FRI...WITH A PRONOUNCED TROUGH SLIDING OFF INTO THE ATLANTIC LEAVING QUASI-ZONAL FLOW IN PLACE ACROSS THE EAST BEFORE NEXT TROUGH MOVES FROM THE NORTHERN PLAINS OVER THE MID-ATLANTIC REGION LATE IN THE SHORT TERM PERIOD. MOST OF THE ACTION WILL COME FROM LOW LEVEL FORCING ASSOCIATED WITH SPRAWLING SFC HIGH SHIFTING FROM THE OHIO VALLEY ONTO THE EASTERN SEABOARD THU NIGHT SETTING UP IN-SITU CAD ACROSS THE CAROLINAS. SFC LOW DEVELOPS IN ITS WAKE OVER THE NRN PLAINS AT THAT TIME...MAGNIFYING SOUTHERLY FLOW ACROSS THE LOWER MISS VALLEY AND LEADING TO DEVELOPMENT OF PRECIP IN THE BAROCLINIC ZONE THERE. THE LOW SHIFTS INTO THE GREAT LAKES REGION OVERNIGHT THU NIGHT PULLING THE BEST ISENTROPIC LIFT AND MOISTURE ADVECTION INTO THE TENN VALLEY BY EARLY FRI MORNING. AS NOTED YESTERDAY...NAM IS FIRST TO BRING PRECIP INTO OUR SW MTNS WITH ACCUMULATIONS ALREADY BY DAYBREAK FRI. HOWEVER THE ISENTROPIC LIFT WITH LOW CONDENSATION PRESSURE DEFICITS IS SEEN ON THE GFS/EC PRIOR TO THAT TIME SO I FAVOR THE EARLY START. THE RELATIVELY RAPID MOVEMENT OF THE LOW MEANS THE PRECIP SHOULD SPREAD EAST QUICKLY AND NOT BE AN ESPECIALLY LONG DURATION EVENT. QPF VALUES ARE HIGHEST FROM THE NAM...WHICH IS A LITTLE SURPRISING GIVEN THE SLIGHTLY HIGHER PWATS SEEN ON THE GFS. FOR THE MOST PART...FAVORED A BLEND OF HPC AND GFS GUIDANCE WHICH WERE FAIRLY CLOSELY MATCHED. THE TRACK OF THE LOW IS SUCH THAT IT COULD ERODE THE CAD WEDGE...AND THE MODELS SHOW THIS. HOWEVER GIVEN THE PRE-EXISTING COLD AIR MASS PRESENTLY IN PLACE AND PAST EXPERIENCE WITH HIGH PRESSURE CENTERS FOLLOWING THIS TRACK...THE WEDGE COULD HOLD STRONG. THE NAM HOLDS ON TO THE WEDGE THE LONGEST OF THE OPNL MODELS AND ALSO HAS THE COOLEST RAW TEMPS. THAT SEEMS LIKE THE MOST PLAUSIBLE SOLUTION SO I FAVORED A BLEND OF RAW NAM AND NAM MOS TEMPS FRIDAY...ALONG WITH NAM THERMAL PROFILES THROUGH THE EVENT. WITH THE STRONG WARM ADVECTION OVERRIDING THE COLD WEDGE...MOST OF THE CWFA LOOKS TO GET MOSTLY FREEZING RAIN. SOME SLEET WILL OCCUR FURTHER NORTH WHERE THE WARM NOSE WILL NOT BE QUITE AS STRONG PER BOURGOUIN PTYPE TECHNIQUE...WITH MOSTLY TO ALL SNOW ACROSS OUR NORTHERN TIER OF COUNTIES. AS THE SFC LOW MOVES INTO THE MID-ATLANTIC AND TURNS FLOW WESTERLY ACROSS THE REGION...MOISTURE AND WARMER AIR ARE PUSHED OUT OF THE PIEDMONT BY FRI EVENING. UPSLOPE WILL ALLOW CONTINUING PRECIP IN THE MTNS. THE SHALLOW MOIST LAYER IS TOO WARM FOR ICE NUCLEATION SO FREEZING RAIN SHOULD RESULT...THOUGH WITH ONLY VERY SMALL ADDITIONAL ACCUMULATION. SAID PCPN IS EXPECTED TO BE CONFINED TO PRIME UPSLOPE AREAS IN THE NRN NC MTNS AND DIMINISH BY MID MORNING SAT. HIGHS WILL REBOUND A BIT OVER THE PIEDMONT GIVEN THE SUNSHINE...BUT STILL SEVERAL DEGREES BELOW NORMAL. THERE IS RELATIVELY HIGH CONFIDENCE IN THE FRIDAY EVENT PRODUCING WINTER WX ACROSS THE REGION. THE SOUTHWEST MOUNTAINS LOOK TO RECEIVE ICE ACCUMULATION OF A QUARTER INCH OR MORE ESPECIALLY AT HIGHER ELEVATIONS. TOGETHER THESE POINTS WARRANT A WINTER STORM WATCH FOR THAT AREA. TEMPERATURES REMAIN SOMEWHAT CRITICAL DURING THE DAY FRIDAY. IF TEMPS ARE ABLE TO WARM SUFFICIENTLY BEFORE THE BULK OF THE PRECIP ARRIVES...THE AREA MAY SEE LARGELY RAIN AND ICE ACCUMS MAY BE LIMITED. THE CURRENT FCST TEMP AND PRECIP TRENDS SUPPORT THE WATCH DESPITE HAVING AFTERNOON TEMPS ABOVE FREEZING AND RAIN AT THAT TIME. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AT 1430 EST WEDNESDAY...AN UPPER TROUGH WILL PROGRESS AWAY FROM THE COAST SATURDAY NIGHT...WHILE AN UPPER RIDGE AMPLIFIES OVER THE PLAINS. THIS RIDGE SLOWLY PROGRESSES TO THE EASTERN USA BY EARLY NEXT WEEK. SURFACE HIGH PRESSURE BEHIND A DEPARTING COLD FRONT WILL MOVE TO THE APPALACHIANS BY SUNDAY...THEN TO THE MID ATLANTIC COAST BY MONDAY. MOIST GULF INFLOW ON THE BACK SIDE OF THIS HIGH WILL REACH OUR AREA MONDAY AND TUESDAY...WHILE THE HIGH MOVES OFFSHORE. GULF INFLOW WILL DIMINISH WEDNESDAY WITH A WEAKENING PRESSURE GRADIENT...WHILE A COLD FRONT APPROACHES FORM THE NORTHWEST. THE FRONT CROSSES OUR AREA DURING THE DAY...FOLLOWED BY MOIST NW FLOW INTO THE NC MOUNTAINS...WHERE TEMPERATURES SHOULD STILL SUPPORT LIQUID PRECIPITATION IN THE AFTERNOON. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... AT KCLT AND OTHER PIEDMONT/FOOTHILL TERMINALS...MOISTURE INCREASES AHEAD OF AN APPROACHING FRONTAL BOUNDARY TONIGHT. THIS MAY RESULT IN SOME SCT/BKN LOW VFR/HIGH MVFR STRATOCU APPROACHING THE UPSTATE SC TERMINALS AND KHKY. MAIN CLOUD HEIGHT WILL BE CIRRUS LEVEL. ANY PRECIPITATION ASSOCIATED WITH THE FRONT IS EXPECTED TO REMAIN CONFINED TO THE MTNS. THE COLD FRONT WILL SWEEP ACROSS THE AREA THURSDAY MORNING...TURNING WINDS TO THE W AND NW THEN N...WITH GUSTS APPROACHING 20 KT POSSIBLE AFTER SUNRISE...MAINLY AT KCLT. GUSTS DIMINISH BY LATE AFTERNOON WITH WINDS BECOMING NE. AT KAVL...UP-VALLEY WINDS WILL CONTINUE THRU THE EVENING...BUT WINDS WILL BE WLY ALOFT. LLWS CANNOT BE RULED OUT...BUT LOOKS LIKE IT WILL BE JUST SHY OF CRITERIA. MOISTURE INCREASING AHEAD OF A COLD FRONT SHOULD RESULT IN LOW VFR STRATOCU...WITH CIGS EXPECTED TO LOWER TO MVFR AS STRONG UP-VALLEY FLOW DEVELOPS IN THE WAKE OF A COLD FRONT. NW GUSTS AROUND 20 KTS ARE EXPECTED BY DAYBREAK WITH 30 KT GUSTS COMMON AFTER SUNRISE THURSDAY. CLOUDS SHOULD GRADUALLY DISSIPATE ON THURSDAY WITH GUSTS NEAR 25 KTS BY MID AFTERNOON THEN DIMINISHING BY SUNSET. OUTLOOK...A COLD FRONT WILL MOVE THROUGH FRIDAY WITH FLIGHT RESTRICTIONS AND A WINTRY MIX LIKELY. DRY HIGH PRESSURE WILL RETURN BY SATURDAY WITH MORE VFR CONDITIONS...PERSISTING INTO MONDAY. AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE CATEGORY IS AVAILABLE AT THE FOLLOWING LINK (USE LOWER CASE)... WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .FIRE WEATHER... FUEL MOISTURE AND MINIMUM RELATIVE HUMIDITY VALUES WILL BE CLOSE TO FIRE DANGER STATEMENT CRITERIA IN NE GA ON THURSDAY. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...WINTER STORM WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY EVENING FOR GAZ010-017. NC...WINTER STORM WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY EVENING FOR NCZ051-052-058-059-062>065. WIND ADVISORY FROM 1 AM TO 1 PM EST THURSDAY FOR NCZ033-049- 050-501-503-505. SC...WINTER STORM WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY EVENING FOR SCZ001>003. && $$ SYNOPSIS...JPT NEAR TERM...JDL/RWH SHORT TERM...WIMBERLEY LONG TERM...JAT AVIATION...RWH FIRE WEATHER...
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
955 AM MST TUE JAN 22 2013 .AVIATION...18Z TAFS AREAS OF MVFR CIGS TOWARDS CTRL SD WILL IMPROVE TO VFR THRU THIS AFTERNOON. OTHERWISE...VFR CONDITIONS WILL PREVAIL THRU THE FORECAST PERIOD. && .PREV DISCUSSION... /ISSUED 829 AM MST TUE JAN 22 2013/ UPDATE...15Z SURFACE ANALYSIS HAD WARM FRONT FROM EAST CENTRAL MT TO THE NE PANHANDLE. 12Z KUNR SOUNDING SHOWED STRONG INVERSION WITH WARM AIR NOT FAR FROM THE SURFACE OVER THE HIGHER ELEVATIONS. AS UPPER RIDGE OVER THE WEST INCHES EAST TODAY...WARM FRONT SHOULD MAKE SOME PROGRESS INTO THE FAR WESTERN SD PLAINS. SHARP TEMPERATURE GRADIENT EXPECTED BY AFTERNOON. 12Z RAP AS WELL AS BUFKIT MOMENTUM TRANSFER GUIDANCE SUGGESTS A FEW BREEZY/GUSTY SPOTS OVER NORTHEAST WY/HIGHER ELEVATIONS OF THE BLACK HILLS FOR THIS AFTERNOON...SO HAVE ADJUSTED ACCORDINGLY. REST OF FORECAST IN GOOD SHAPE. PREV DISCUSSION... /ISSUED 256 AM MST TUE JAN 22 2013/ DISCUSSION...STAUNCH WESTERN CONUS RIDGE CONTINUES TO SLOWLY PUSH EAST...HOWEVER...THE ENTRENCHED ARCTIC AIR MASS IS REFUSING TO EXIT EASY. ANOTHER STRONG COMPACT FAST MOVING MID LEVEL IMPULSE IS DIVING SE ACROSS MB...AND WILL HELP REINFORCE THE CURRENT AIR MASS ACROSS THE NORTHERN PLAINS. OTHERWISE...WAA IS ONGOING ACROSS THE REGION...WITH VERY WARM TEMPS IN PLACE ACROSS NE WY AND THE BH PER A DECENTLY MIXED BL. LIGHT SNOW/FLURRIES CONTINUE OVER THE EASTERN FA PER THE WAA INDUCED UPGLIDE...WITH THIS AREA CONTINUING TO SHIFT EAST. OTHERWISE....A RATHER STRONG NE PAC UPPER TROUGH IS ADVANCING INTO THE WESTERN NOAM RIDGE AND WILL EVENTUALLY SPAWN A CLIPPER SYSTEM INTO THE REGION...AFFECTING THE LOCAL AREA WED INTO THUR. STRONG TEMP GRADIENT WILL CONTINUE ACROSS THE FA TODAY...WITH HIGHS NEAR 50 IN NE WY TO THE LOWER 20S OVER THE EAST. SFC WARM FRONT WILL STRUGGLE EAST OFF THE HIGHER TERRAIN GIVEN A RATHER STRONG WAA INVERSION IN PLACE AND RELATIVELY POOR LL FLOW TO SUPPORT MIXING. CONTINUED LIGHT SNOW SHOWER CHANCES THIS MORNING ACROSS THE FAR EAST...WITH DRY CONDITIONS THIS AFTERNOON ALL PLACES. AMPLE SUNSHINE EXPECTED WESTERN AREAS...WITH FGEN CLOUDS LINGERING OVER THE EAST THROUGH MUCH OF THE DAY. LL FLOW WILL BEGIN TO RESPOND TO THE ADVECTING NW CONUS UPPER IMPULSE WED...WITH SFC PRESSURE FALLS UPTICKING OVER NE WY. MEANWHILE...TODAY/S MB TROUGH WILL SUPPORT A COLD PUSH ACROSS THE EASTERN NORTHERN PLAINS TONIGHT...WHICH WILL SETTLE WEST INTO THE FA GIVEN SFC PRESSURE FALLS IN THE LEE OF THE ROCKIES SUPPORTING EASTERLY FLOW. FORECAST MODELS HAVE TRENDED MUCH COLDER PER TEMPS OVER THE EASTERN 2/3 OF THE FA WED...AND HAVE CUT HIGHS SIG FOR THIS. UPSLOPE COMPONENT TO THE FLOW CERTAINLY WILL NOT HELP THINGS EITHER. LL EASTERLY UPSLOPE /SUFFICIENTLY MOIST/ FLOW MAY SUPPORT LOW CLOUDS OVER THE SD PLAINS BY WED AFTERNOON/EVENING...WITH FOG POSSIBLE OVER THE EASTERN BH FOOTHILLS BY EVENING. HAVE INTRODUCED A PATCHY FOG MENTION FOR THIS. MEANWHILE NE WY AND THE BH WILL REMAIN QUITE WARM...AS THE LL COLD AIR MASS WILL REMAIN SHALLOW AND CONFINED TO LOWER TERRAIN. KEPT WARM TEMPS IN THIS REGION THROUGH WED. CLIPPER SYSTEM WILL SHIFT WINDS WESTERLY OVER THE ENTIRE FA THUR...WITH BL WARM DOWNSLOPE FLOW EXPECTED TO MIX DOWN AT MOST PLACES...ESP THE SW 3/4. HAVE CUT BACK ON POPS WITH THIS SYSTEM GIVEN LACK OF APPRECIABLE MOISTURE WITH BEST LL AND MID LEVEL FORCING EXPECTED TO REMAIN NORTH OF THE FA. REMOVED POPS WED NIGHT AND RETAINED A LOW CHANCE MENTION ACROSS THE NORTH THUR. PERHAPS THE MAIN IMPACT FROM THIS SYSTEM WILL BE WINDS ON THE BACKSIDE OF THIS SYSTEM THUR AFTERNOON AND EVENING. DECENT PRESSURE RISE/CAA COMBO SHOULD SUPPORT ADV TO NEAR ADV CRITERIA FOR MUCH OF NW SD. COLD AIR WILL FILTER BACK INTO MUCH OF THE AREA THUR NIGHT...WITH WINDS SLOWLY SUBSIDING. EXTENDED...RIDGE OVER THE WRN CONUS WILL SLOWLY SHIFT EAST ACROSS THE NORTHERN PLAINS THROUGH THE WEEKEND...BRINGING MILD AND DRY CONDITIONS. MODELS START TO DIVERGE ON A SOLUTION TO START NEXT WEEK THOUGH OVERALL PATTERN REMAINS UNSETTLED...SO WILL LEAVE LOW POPS IN FOR NOW. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ SHORT TERM...WFO UNR LONG TERM....WFO UNR AVIATION...77
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
829 AM MST TUE JAN 22 2013 .UPDATE...15Z SURFACE ANALYSIS HAD WARM FRONT FROM EAST CENTRAL MT TO THE NE PANHANDLE. 12Z KUNR SOUNDING SHOWED STRONG INVERSION WITH WARM AIR NOT FAR FROM THE SURFACE OVER THE HIGHER ELEVATIONS. AS UPPER RIDGE OVER THE WEST INCHES EAST TODAY...WARM FRONT SHOULD MAKE SOME PROGRESS INTO THE FAR WESTERN SD PLAINS. SHARP TEMPERATURE GRADIENT EXPECTED BY AFTERNOON. 12Z RAP AS WELL AS BUFKIT MOMENTUM TRANSFER GUIDANCE SUGGESTS A FEW BREEZY/GUSTY SPOTS OVER NORTHEAST WY/HIGHER ELEVATIONS OF THE BLACK HILLS FOR THIS AFTERNOON...SO HAVE ADJUSTED ACCORDINGLY. REST OF FORECAST IN GOOD SHAPE. && .AVIATION...12Z TAFS FLURRIES OVER NORTHWEST INTO CENTRAL SOUTH DAKOTA WILL CONTINUE TO MOVE EAST OUT OF THE AREA THIS MORNING. OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. && .PREV DISCUSSION... /ISSUED 256 AM MST TUE JAN 22 2013/ DISCUSSION...STAUNCH WESTERN CONUS RIDGE CONTINUES TO SLOWLY PUSH EAST...HOWEVER...THE ENTRENCHED ARCTIC AIR MASS IS REFUSING TO EXIT EASY. ANOTHER STRONG COMPACT FAST MOVING MID LEVEL IMPULSE IS DIVING SE ACROSS MB...AND WILL HELP REINFORCE THE CURRENT AIR MASS ACROSS THE NORTHERN PLAINS. OTHERWISE...WAA IS ONGOING ACROSS THE REGION...WITH VERY WARM TEMPS IN PLACE ACROSS NE WY AND THE BH PER A DECENTLY MIXED BL. LIGHT SNOW/FLURRIES CONTINUE OVER THE EASTERN FA PER THE WAA INDUCED UPGLIDE...WITH THIS AREA CONTINUING TO SHIFT EAST. OTHERWISE....A RATHER STRONG NE PAC UPPER TROUGH IS ADVANCING INTO THE WESTERN NOAM RIDGE AND WILL EVENTUALLY SPAWN A CLIPPER SYSTEM INTO THE REGION...AFFECTING THE LOCAL AREA WED INTO THUR. STRONG TEMP GRADIENT WILL CONTINUE ACROSS THE FA TODAY...WITH HIGHS NEAR 50 IN NE WY TO THE LOWER 20S OVER THE EAST. SFC WARM FRONT WILL STRUGGLE EAST OFF THE HIGHER TERRAIN GIVEN A RATHER STRONG WAA INVERSION IN PLACE AND RELATIVELY POOR LL FLOW TO SUPPORT MIXING. CONTINUED LIGHT SNOW SHOWER CHANCES THIS MORNING ACROSS THE FAR EAST...WITH DRY CONDITIONS THIS AFTERNOON ALL PLACES. AMPLE SUNSHINE EXPECTED WESTERN AREAS...WITH FGEN CLOUDS LINGERING OVER THE EAST THROUGH MUCH OF THE DAY. LL FLOW WILL BEGIN TO RESPOND TO THE ADVECTING NW CONUS UPPER IMPULSE WED...WITH SFC PRESSURE FALLS UPTICKING OVER NE WY. MEANWHILE...TODAY/S MB TROUGH WILL SUPPORT A COLD PUSH ACROSS THE EASTERN NORTHERN PLAINS TONIGHT...WHICH WILL SETTLE WEST INTO THE FA GIVEN SFC PRESSURE FALLS IN THE LEE OF THE ROCKIES SUPPORTING EASTERLY FLOW. FORECAST MODELS HAVE TRENDED MUCH COLDER PER TEMPS OVER THE EASTERN 2/3 OF THE FA WED...AND HAVE CUT HIGHS SIG FOR THIS. UPSLOPE COMPONENT TO THE FLOW CERTAINLY WILL NOT HELP THINGS EITHER. LL EASTERLY UPSLOPE /SUFFICIENTLY MOIST/ FLOW MAY SUPPORT LOW CLOUDS OVER THE SD PLAINS BY WED AFTERNOON/EVENING...WITH FOG POSSIBLE OVER THE EASTERN BH FOOTHILLS BY EVENING. HAVE INTRODUCED A PATCHY FOG MENTION FOR THIS. MEANWHILE NE WY AND THE BH WILL REMAIN QUITE WARM...AS THE LL COLD AIR MASS WILL REMAIN SHALLOW AND CONFINED TO LOWER TERRAIN. KEPT WARM TEMPS IN THIS REGION THROUGH WED. CLIPPER SYSTEM WILL SHIFT WINDS WESTERLY OVER THE ENTIRE FA THUR...WITH BL WARM DOWNSLOPE FLOW EXPECTED TO MIX DOWN AT MOST PLACES...ESP THE SW 3/4. HAVE CUT BACK ON POPS WITH THIS SYSTEM GIVEN LACK OF APPRECIABLE MOISTURE WITH BEST LL AND MID LEVEL FORCING EXPECTED TO REMAIN NORTH OF THE FA. REMOVED POPS WED NIGHT AND RETAINED A LOW CHANCE MENTION ACROSS THE NORTH THUR. PERHAPS THE MAIN IMPACT FROM THIS SYSTEM WILL BE WINDS ON THE BACKSIDE OF THIS SYSTEM THUR AFTERNOON AND EVENING. DECENT PRESSURE RISE/CAA COMBO SHOULD SUPPORT ADV TO NEAR ADV CRITERIA FOR MUCH OF NW SD. COLD AIR WILL FILTER BACK INTO MUCH OF THE AREA THUR NIGHT...WITH WINDS SLOWLY SUBSIDING. EXTENDED...RIDGE OVER THE WRN CONUS WILL SLOWLY SHIFT EAST ACROSS THE NORTHERN PLAINS THROUGH THE WEEKEND...BRINGING MILD AND DRY CONDITIONS. MODELS START TO DIVERGE ON A SOLUTION TO START NEXT WEEK THOUGH OVERALL PATTERN REMAINS UNSETTLED...SO WILL LEAVE LOW POPS IN FOR NOW. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ SHORT TERM...HELGESON LONG TERM...WFO UNR AVIATION...WFO UNR UPDATE...WFO UNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1008 PM MST MON JAN 21 2013 .AVIATION...06Z TAF FORECASTS SNOW FLURRIES ON THE WESTERN SD PLAINS WILL GRADUALLY SHIFT EAST AND TAPER OFF OVERNIGHT. AREAS OF MVFR CIGS OVER WESTERN SOUTH DAKOTA WILL IMPROVE TO VFR TUESDAY MORNING. && PREV DISCUSSION... /ISSUED 431 PM MST MON JAN 21 2013/ DISCUSSION...21Z SURFACE ANALYSIS HAD WARM FRONT FROM CENTRAL MT INTO WESTERN NE. LIFT ALONG 140KT JET STREAK ON COLD SIDE OF WARM FRONT CONTINUING TO PRODUCE -SN OVER WESTERN SD PER KUDX RADAR. 12Z GUIDANCE AS WELL AS 18Z RAP SHOW ACTIVITY WANING AND SLOWLY MOVING EAST TONIGHT. MOST ACTIVITY SHOULD EXIT CWA BY 12Z TUESDAY. ACCUMULATIONS WILL CONTINUE TO BE MINOR. TEMPERATURES NEAR GUIDANCE LOOK REASONABLE. TUESDAY...UPPER RIDGE BUILDS EAST INTO THE ROCKIES AS SURFACE WARM FRONT WORKS ACROSS WESTERN SD. HOW FAR EAST IT GOES IT THE MAIN QUESTION...BUT IT SHOULD AT LEAST MAKE IT TO A K2WX TO KVTN LINE. BEHIND IT TEMPERATURES SHOULD REACH WELL INTO THE 30S TO LOWER 40S GIVEN FORECAST LOWER TROPOSPHERIC PROFILES. WEDNESDAY...UPPER RIDGE MOVES OVER THE NORTHERN PLAINS AND DEAMPLIFIES AS SHORTWAVE TROUGHS MOVES INTO THE NORTHERN ROCKIES. INITIAL TROUGH/COOL FRONT WILL SLIDE INTO THE CWA. TEMPERATURES SHOULD ROCKET INTO THE 40S OVER WY/HIGHER ELEVATIONS...BUT AS AN EASTERLY COMPONENT TO THE SURFACE WIND DEVELOPS ON THE SD PLAINS BY AFTERNOON...EXPECT TEMPERATURES RISES TO BE HALTED MAINLY IN THE 20S. ST/BR MAY DEVELOP WEDNESDAY NIGHT GIVEN WEAK UPSLOPE FLOW AHEAD OF NEXT FRONT FOR THURSDAY. EXTENDED...A FAST MOVING CLIPPER SYSTEM WILL MOVE THROUGH THE NRN PLAINS ON THURSDAY...BRINGING GUSTY NORTHWEST WINDS ALONG WITH CHANCES FOR PRECIP MAINLY OVER THE NRN CWA. RIDGE OVER THE WRN CONUS WILL THEN SLOWLY SHIFT EAST...BRINGING MILD AND DRY CONDITIONS FOR THE WEEKEND. MODELS START TO DIVERGE ON A SOLUTION TO START NEXT WEEK THOUGH OVERALL PATTERN REMAINS UNSETTLED...SO WILL LEAVE LOW POPS IN FOR NOW. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
645 AM EST TUE JAN 22 2013 .SYNOPSIS... HIGH PRESSURE WITH VERY COLD AIR WILL COVER THE AREA TODAY AND WEDNESDAY. A LOW PRESSURE SYSTEM WILL MOVE FROM THE PLAINS ON THURSDAY INTO THE OHIO VALLEY AND MID ATLANTIC REGION ON FRIDAY. HIGH PRESSURE AND MORE COLD AIR IS EXPECTED SATURDAY AND SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 345 AM EST TUESDAY... A COUPLE OF WEAK SHORT WAVES AND STRING UPSLOPE IN EASTERN WET VIRGINIA HAVE SQUEEZED ENOUGH LOW LEVEL MOISTURE OUT OF THIS ARCTIC AIRMASS FOR LOW CLOUDS ALONG THE WESTERN SLOPES OF THE MOUNTAINS FROM GREENBRIER COUNTY NORTH INTO CENTRAL PENNSYLVANIA. AREA NATIONAL WEATHER SERVICE RADARS SHOWED ONLY MINIMAL SHOW SHOWER COVERAGE IN SOUTHEAST WEST VIRGINIA. SUBTLE SHORT WAVES WILL CONTINUE TO ROTATE THROUGH THE LONG WAVE THROUGH TODAY AND TONIGHT. THE RUC AND OOZE WRF SUGGEST THE LOWER CLOUDS MAY EXPAND SOUTH TO BLUEFIELD AND TAZEWELL COUNTY THIS MORNING. OTHERWISE AS A JET STREAK CROSSES THE FORECAST AREA EXPECT MOUNTAIN CIRRUS ON THE EAST SLOPES OF THE CENTRAL AND SOUTHERN APPALACHIANS THIS EVENING. HAVE ADJUSTED CLOUD COVER FORECAST FOR THESE TRENDS. AIR MASS UPSTREAM AT 00Z HAD 850 MB TEMPERATURES FROM -15 TO -20 AND SURFACE DEW POINTS WELL BELOW ZERO. HAVE GONE COLDER THAN GUIDANCE FOR BOTH HIGHS TODAY AND LOWS TONIGHT. SURFACE PRESSURE CONTINUES TO RISE TODAY AND BY WEDNESDAY MORNING THE CENTER OF THE HIGH WILL BE OVER EASTERN TENNESSEE. WIND WILL BEGIN TO DIMINISH THIS MORNING AND WILL BE MUCH LIGHTER IN THE VALLEYS TONIGHT. AT THE HIGHER ELEVATIONS OF BATH...GREENBRIER AND ALLEGHANY VIRGINIA...WIND CHILLS STAY CLOSE TO THE ZERO TO -5 RANGE DESPITE THE DECREASING WIND SPEEDS. HAVE EXTENDED THE WIND CHILL ADVISORY IN THESE COUNTIES THROUGH WEDNESDAY MORNING. ANOTHER ADVISORY MADE BE NEEDED FOR LATE TONIGHT FOR THE WESTERN PART OF THE FORECAST AREA. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... AS OF 400 AM EST TUESDAY... COMPLEX FORECAST FOR THE LATER HALF OF THE WEEK. ARCTIC AIR WILL BE FIRMLY ENTRENCHED ACROSS THE FORECAST AREA EARLY WEDNESDAY MORNING. UPPER TROUGH/POLAR VORTEX OVER ERN CANADA WILL MOVE VERY LITTLE FROM WEDNESDAY THROUGH FRIDAY...ALTHOUGH WILL SEE BRIEF RETREAT OF COLDEST AIR WEDNESDAY AND AGAIN FRIDAY AHEAD OF TWO SEPARATE SHORT WAVES THAT WILL CROSS THE REGION DURING THIS TIME FRAME. THE FIRST WAVE WILL MOVE THROUGH THE GREAT LAKES AND ALONG THE MASON- DIXON WEDNESDAY NIGHT. THIS WILL CAUSE WINDS TO BACK WITH DEVELOPMENT OF ISENTROPIC LIFT ACROSS THE OHIO VALLEY WEDNESDAY... THIS AREA OF FORCING SCOOTING BY TO OUR NORTH WEDNESDAY NIGHT. AT THE VERY LEAST SHOULD SEE INCREASING CLOUDINESS WEDNESDAY...CLOUDS THICKENING PRIOR TO THE PASSAGE OF THE SHORTWAVE WEDNESDAY NIGHT. A BRIEF PERIOD OF LIGHT SNOW OR FLURRIES IS POSSIBLE...BUT MAINLY FOR THE WV MTNS AND VA HIGHLANDS. FORECAST BUFKIT SOUNDINGS INDICATE LITTLE IN THE WAY OF PRECIP REACHING THE GROUND PER VERY DRY AIRMASS OVER THE FCST AREA. AS SUCH...RUNNING WITH VERY LOW POPS WEDNESDAY NIGHT WITH LITTLE (UPWARDS OF AN INCH IN NW GREENBRIER?) OR NO SNOW ACCUMULATION. PASSAGE OF THIS WAVE WILL BRING REINFORCING SURGE OF ARCTIC AIR TO THE AREA THURSDAY. THE SECOND SHORT WAVE IS FORECAST TO DIP A BIT FARTHER SOUTH... TAPPING RIBBON OF GULF MOISTURE FOR FRIDAY. AREA OF ISENTROPIC LIFT IS FORECAST TO PASS ALMOST DIRECTLY OVHD WITH ENOUGH LIFT TO GENERATE UPWARDS OF A THIRD OF AN INCH OF QPF. THE SUBFREEZING ANTECEDENT CONDITIONS SUGGEST WE WILL BE LOOKING AT P-TYPE ISSUES WITH POTENTIAL FOR BOTH FREEZING AND FROZEN PRECIPITATION AREAWIDE...AND COVERING A LARGE GEOGRAPHIC SWATH FROM THE OHIO VALLEY EASTWARD THROUGH THE MID ATLANTIC AND POINTS NORTH. FOR OUR CWA...ESP THE SOUTHERN HALF...MODEL FORECAST SOUNDINGS INDICATE WARM NOSE (+1 TO +3 DEG C) VCNTY OF 800 MB TO OVERRIDE THE SHALLOW BUT VERY COLD BOUNDARY LAYER. LATEST MODELS HAVE TRENDED COLDER WITH THIS SYSTEM SUGGESTING A GOOD PORTION OF THE QPF MAY BE SNOW OR SLEET B4 CHANGING TO FREEZING RAIN. ATTM THINK WE WILL BE LOOKING AT WINTER WEATHER ADVISORY CONDITIONS FRIDAY. WOULD NEED A BIT MORE QPF...OR...FOR ALL OF THE PRECIP TO FALL AS FREEZING RAIN IN ORDER TO JUSTIFY A WATCH/WARNING SORT OF CONCERN. AT THE VERY LEAST...THIS WILL BE A CONCERN FOR SCHOOLS/DOT/TRAVEL INTERESTS AS THE GROUND WILL BE FROZEN ALLOWING FOR EASY ACCUMULATION FOR WHATEVER WINTER PTYPE OCCURS. TEMPERATURES THROUGH THE END OF THE WEEK WILL STRUGGLE TO REACH FREEZING. EVEN FOR AREAS THAT MANAGE TO GET ABOVE FREEZING...THE WETBULB WILL REMAIN BELOW 32. THIS SUGGESTS THE REMAINING SNOW COVER IN THE MOUNTAINS IS NOT GOING ANYWHERE FOR THE REST OF THIS WEEK. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 400 AM EST TUESDAY... ANY WARM AIR THAT TRIES TO DISPLACE THE COLD AIR FRIDAY WILL GET SQUASHED BY SATURDAY. NORTHWEST WINDS ARE FORECAST TO DEVELOP IN THE WAKE OF FRIDAYS SYSTEM...85H TEMPS DIPPING BACK DOWN TO NEAR M15 BY SATURDAY MORNING. THIS SAME NORTHWEST FLOW WILL RESULT IN PERSISTENT CLOUDS/-SHSN/FLURRIES OVER THE MOUNTAINS WITH DRY BUT BRISK CONDITIONS ELSEWHERE. SUNDAY WILL BRING TRANSITION BACK TO SUNNY SKIES...WINDS DIMINISHING...1035 MB HIGH PRESSURE PASSING OVERHD. A WARMING TREND IS EXPECTED TO GET UNDERWAY FOR THE FOLLOWING WEEK AS SOUTHERLY WINDS DEVELOP AROUND THE DEPARTING ANTICYCLONE...TEMPERATURES TRENDING BACK ABOVE NORMAL. THE PATTERN ALSO LOOKS WET...WIND FLOW COMING UP FROM THE GULF COAST REGION. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 630 AM EST TUESDAY... SATELLITE PICTURES SHOWED A SMALL PERSISTENT PATCH OF VFR CLOUDS IN WESTERN GREENBRIER COUNTY THIS MORNING. EXPECT THIS CLOUD COVER TO STAY WEST OF LWB TODAY. UPPER JET CROSSING THE SOUTHERN APPALACHIANS THIS EVENING MAY PRODUCE A SCT TO BKN LAYER OF CIRRUS EAST OF THE APPALACHIANS TONIGHT. HIGH CONFIDENCE THAT BLF/LWB/BCB/ROA/LYH AND DAN WILL BE VFR THROUGH THE TAF FORECAST PERIOD. WINDS WILL BE GUSTY FROM 290 TO 310 TODAY WITH WIND SPEEDS GRADUALLY DIMINISHING AFTER NOON. AS SURFACE HIGH PRESSURE BUILDS IN TO THE AREA TONIGHT...WINDS WILL DECOUPLE IN THE WEST VALLEYS...INCLUDING AT LWB...BECOMING CALM TO LIGHT AND VARIABLE. ISENTROPIC LIFT AHEAD A DEVELOPING LOW PRESSURE SYSTEM TRACKING FROM THE PLAINS TO THE TENNESSEE VALLEY ON THURSDAY WILL SPREAD CLOUDS COVER ACROSS THE REGION BY THURSDAY NIGHT. MODELS HAVE SLOWED DOWN ARRIVAL OF THE PRECIPITATION WITH MOST GUIDANCE HOLDING OFF UNTIL AFTER 12Z/7AM FRIDAY. SOME FORM OF WINTER PRECIPITATION IS LIKELY BUT THE CONFIDENCE ON WHICH PRECIPITATION TYPE IS LOW. AT THIS TIME THE MOST LIKELY IS FOR SLEET AND FREEZING RAIN WITH IFR CEILINGS ON FRIDAY. AS THIS SYSTEM MOVES OFFSHORE BY SATURDAY MORNING...WIND GUST TO 30 KTS ARE POSSIBLE. CEILINGS AND POSSIBLY VISIBILITIES WILL REMAIN MVFR WITH SNOW SHOWERS AT BLF AND LWB THROUGH FRIDAY NIGHT..BUT WILL BE VFR AT ROA/DAN/LYH FRIDAY NIGHT AND SATURDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR VAZ007-009>018- 023-024. WIND CHILL ADVISORY UNTIL NOON EST WEDNESDAY FOR VAZ019-020. NC...WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR NCZ001-002-018. WV...WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR WVZ042>044. WIND CHILL ADVISORY UNTIL NOON EST WEDNESDAY FOR WVZ045. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...PM LONG TERM...PM/RCS AVIATION...AMS/PM
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
420 AM EST TUE JAN 22 2013 .SYNOPSIS... HIGH PRESSURE WITH VERY COLD AIR WILL COVER THE AREA TODAY AND WEDNESDAY. A LOW PRESSURE SYSTEM WILL MOVE FROM THE PLAINS ON THURSDAY INTO THE OHIO VALLEY AND MID ATLANTIC REGION ON FRIDAY. HIGH PRESSURE AND MORE COLD AIR IS EXPECTED SATURDAY AND SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 345 AM EST TUESDAY... A COUPLE OF WEAK SHORT WAVES AND STRING UPSLOPE IN EASTERN WET VIRGINIA HAVE SQUEEZED ENOUGH LOW LEVEL MOISTURE OUT OF THIS ARCTIC AIRMASS FOR LOW CLOUDS ALONG THE WESTERN SLOPES OF THE MOUNTAINS FROM GREENBRIER COUNTY NORTH INTO CENTRAL PENNSYLVANIA. AREA NATIONAL WEATHER SERVICE RADARS SHOWED ONLY MINIMAL SHOW SHOWER COVERAGE IN SOUTHEAST WEST VIRGINIA. SUBTLE SHORT WAVES WILL CONTINUE TO ROTATE THROUGH THE LONG WAVE THROUGH TODAY AND TONIGHT. THE RUC AND OOZE WRF SUGGEST THE LOWER CLOUDS MAY EXPAND SOUTH TO BLUEFIELD AND TAZEWELL COUNTY THIS MORNING. OTHERWISE AS A JET STREAK CROSSES THE FORECAST AREA EXPECT MOUNTAIN CIRRUS ON THE EAST SLOPES OF THE CENTRAL AND SOUTHERN APPALACHIANS THIS EVENING. HAVE ADJUSTED CLOUD COVER FORECAST FOR THESE TRENDS. AIR MASS UPSTREAM AT 00Z HAD 850 MB TEMPERATURES FROM -15 TO -20 AND SURFACE DEW POINTS WELL BELOW ZERO. HAVE GONE COLDER THAN GUIDANCE FOR BOTH HIGHS TODAY AND LOWS TONIGHT. SURFACE PRESSURE CONTINUES TO RISE TODAY AND BY WEDNESDAY MORNING THE CENTER OF THE HIGH WILL BE OVER EASTERN TENNESSEE. WIND WILL BEGIN TO DIMINISH THIS MORNING AND WILL BE MUCH LIGHTER IN THE VALLEYS TONIGHT. AT THE HIGHER ELEVATIONS OF BATH...GREENBRIER AND ALLEGHANY VIRGINIA...WIND CHILLS STAY CLOSE TO THE ZERO TO -5 RANGE DESPITE THE DECREASING WIND SPEEDS. HAVE EXTENDED THE WIND CHILL ADVISORY IN THESE COUNTIES THROUGH WEDNESDAY MORNING. ANOTHER ADVISORY MADE BE NEEDED FOR LATE TONIGHT FOR THE WESTERN PART OF THE FORECAST AREA. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... AS OF 400 AM EST TUESDAY... COMPLEX FORECAST FOR THE LATER HALF OF THE WEEK. ARCTIC AIR WILL BE FIRMLY ENTRENCHED ACROSS THE FORECAST AREA EARLY WEDNESDAY MORNING. UPPER TROUGH/POLAR VORTEX OVER ERN CANADA WILL MOVE VERY LITTLE FROM WEDNESDAY THROUGH FRIDAY...ALTHOUGH WILL SEE BRIEF RETREAT OF COLDEST AIR WEDNESDAY AND AGAIN FRIDAY AHEAD OF TWO SEPARATE SHORT WAVES THAT WILL CROSS THE REGION DURING THIS TIME FRAME. THE FIRST WAVE WILL MOVE THROUGH THE GREAT LAKES AND ALONG THE MASON- DIXON WEDNESDAY NIGHT. THIS WILL CAUSE WINDS TO BACK WITH DEVELOPMENT OF ISENTROPIC LIFT ACROSS THE OHIO VALLEY WEDNESDAY... THIS AREA OF FORCING SCOOTING BY TO OUR NORTH WEDNESDAY NIGHT. AT THE VERY LEAST SHOULD SEE INCREASING CLOUDINESS WEDNESDAY...CLOUDS THICKENING PRIOR TO THE PASSAGE OF THE SHORTWAVE WEDNESDAY NIGHT. A BRIEF PERIOD OF LIGHT SNOW OR FLURRIES IS POSSIBLE...BUT MAINLY FOR THE WV MTNS AND VA HIGHLANDS. FORECAST BUFKIT SOUNDINGS INDICATE LITTLE IN THE WAY OF PRECIP REACHING THE GROUND PER VERY DRY AIRMASS OVER THE FCST AREA. AS SUCH...RUNNING WITH VERY LOW POPS WEDNESDAY NIGHT WITH LITTLE (UPWARDS OF AN INCH IN NW GREENBRIER?) OR NO SNOW ACCUMULATION. PASSAGE OF THIS WAVE WILL BRING REINFORCING SURGE OF ARCTIC AIR TO THE AREA THURSDAY. THE SECOND SHORT WAVE IS FORECAST TO DIP A BIT FARTHER SOUTH... TAPPING RIBBON OF GULF MOISTURE FOR FRIDAY. AREA OF ISENTROPIC LIFT IS FORECAST TO PASS ALMOST DIRECTLY OVHD WITH ENOUGH LIFT TO GENERATE UPWARDS OF A THIRD OF AN INCH OF QPF. THE SUBFREEZING ANTECEDENT CONDITIONS SUGGEST WE WILL BE LOOKING AT P-TYPE ISSUES WITH POTENTIAL FOR BOTH FREEZING AND FROZEN PRECIPITATION AREAWIDE...AND COVERING A LARGE GEOGRAPHIC SWATH FROM THE OHIO VALLEY EASTWARD THROUGH THE MID ATLANTIC AND POINTS NORTH. FOR OUR CWA...ESP THE SOUTHERN HALF...MODEL FORECAST SOUNDINGS INDICATE WARM NOSE (+1 TO +3 DEG C) VCNTY OF 800 MB TO OVERRIDE THE SHALLOW BUT VERY COLD BOUNDARY LAYER. LATEST MODELS HAVE TRENDED COLDER WITH THIS SYSTEM SUGGESTING A GOOD PORTION OF THE QPF MAY BE SNOW OR SLEET B4 CHANGING TO FREEZING RAIN. ATTM THINK WE WILL BE LOOKING AT WINTER WEATHER ADVISORY CONDITIONS FRIDAY. WOULD NEED A BIT MORE QPF...OR...FOR ALL OF THE PRECIP TO FALL AS FREEZING RAIN IN ORDER TO JUSTIFY A WATCH/WARNING SORT OF CONCERN. AT THE VERY LEAST...THIS WILL BE A CONCERN FOR SCHOOLS/DOT/TRAVEL INTERESTS AS THE GROUND WILL BE FROZEN ALLOWING FOR EASY ACCUMULATION FOR WHATEVER WINTER PTYPE OCCURS. TEMPERATURES THROUGH THE END OF THE WEEK WILL STRUGGLE TO REACH FREEZING. EVEN FOR AREAS THAT MANAGE TO GET ABOVE FREEZING...THE WETBULB WILL REMAIN BELOW 32. THIS SUGGESTS THE REMAINING SNOWCOVER IN THE MOUNTAINS IS NOT GOING ANYWHERE FOR THE REST OF THIS WEEK. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 400 AM EST TUESDAY... ANY WARM AIR THAT TRIES TO DISPLACE THE COLD AIR FRIDAY WILL GET SQUASHED BY SATURDAY. NORTHWEST WINDS ARE FORECAST TO DEVELOP IN THE WAKE OF FRIDAYS SYSTEM...85H TEMPS DIPPING BACK DOWN TO NEAR M15 BY SATURDAY MORNING. THIS SAME NORTHWEST FLOW WILL RESULT IN PERSISTENT CLOUDS/-SHSN/FLURRIES OVER THE MOUNTAINS WITH DRY BUT BRISK CONDITIONS ELSEWHERE. SUNDAY WILL BRING TRANSITION BACK TO SUNNY SKIES...WINDS DIMINISHING...1035 MB HIGH PRESSURE PASSING OVERHD. A WARMING TREND IS EXPECTED TO GET UNDERWAY FOR THE FOLLOWING WEEK AS SOUTHERLY WINDS DEVELOP AROUND THE DEPARTING ANTICYCLONE...TEMPERATURES TRENDING BACK ABOVE NORMAL. THE PATTERN ALSO LOOKS WET...WINDFLOW COMING UP FROM THE GULF COAST REGION. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/... AS OF 125 AM EST TUESDAY... COLD HIGH PRESSURE OVER THE NORTHERN PLAINS WILL MOVE SOUTHEAST TO TENNESSEE VALLEY/EASTERN GULF COAST BY WEDNESDAY MORNING. THE COLD AIR WILL FLOW OVER THE GREAT LAKES AIDING IN THE DEVELOPMENT OF LAKE EFFECT SNOW DOWNWIND FROM THE GREAT LAKES THROUGH WEDNESDAY MORNING. THIS WILL RESULT IN THE POTENTIAL FOR MVFR CONDITIONS VCNTY OF BLF/LWB BY MID WEEK. EAST OF THE MTNS...PRIMARILY VFR CONDITIONS EXPECTED THROUGH THE TAF PD. WINDS WILL BE GUSTY ATTMS WITH SFC GUSTS APPROACHING 30KTS FROM THE WEST OR NORTHWEST TONIGHT INTO TUESDAY MORNING. ISENTROPIC LIFT/WARM FRONT MAY BRING LIGHT FREEZING DRIZZLE OR FLURRIES TO LWB/BLF FOR A FEW HOURS ON THURSDAY OR THURSDAY NIGHT. A LOW PRESSURE SYSTEM AND FRONT MOVING THROUGH THE TN VALLEY MAY OVERSPREAD THE REGION WITH RAIN/FREEZING RAIN/SNOW/SLEET WITH IFR CIGS BLF/LWB/BCB LATE FRIDAY OR FRIDAY NIGHT. WINDS MAY ALSO GUST TO 30 KTS IN THE WAKE OF FRIDAYS WEATHER SYSTEM. GUSTY WINDS CONTINUE SATURDAY WITH IFR CIGS/VIS POTENTIALLY WITH SNOW SHOWERS AT LWB/BLF. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR VAZ007-009>018- 023-024. WIND CHILL ADVISORY UNTIL NOON EST WEDNESDAY FOR VAZ019-020. NC...WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR NCZ001-002-018. WV...WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR WVZ042>044. WIND CHILL ADVISORY UNTIL NOON EST WEDNESDAY FOR WVZ045. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...PM LONG TERM...PM/RCS AVIATION...AMS/PM
AREA FORECAST DISCUSSION...UPDATED
NWS GREEN BAY WI
745 PM CST WED JAN 23 2013 .UPDATE...MUCH AS WITH THE INFLUX OF THE ARCTIC AIR SATURDAY EVENING...SHSN WOUND UP BEING MORE SIG THAN INITIALLY EXPECTED. BUT OTHER THAN THE LAKE-EFFECT AFFECTING N-C WI AND SOME LAKE- EFFECT PUSHING INTO THE NORTHERN DOOR...THE LAST SIG SHSN WAS EXITING THE FCST AREA OVER SRN LAKE WINNEBAGO. SKIES CLEARING RAPIDLY IN THE STG SUBSIDENCE BEHIND THE DEPARTING SHRTWV AND IN THE CAA REGIME AHEAD OF STG ANTICYCLONE HEADING INTO THE RGN. A FEW REPORTS OF SIG SNOWS RECEIVED FM THE DLH OFFICE FM IRON COUNTY WI. BUT FLOW ACRS LAKE SUPERIOR IS A BIT TOO NLY TO BE IDEAL FOR VILAS COUNTY...SO THINK REALLY SIG SNOWS WL REMAIN JUST W/NW OF VILAS. WIND CHILL SITN NOT REAL CLEAR CUT. A PERIOD OF GUSTY WINDS EXPECTED THIS EVENING AS COLD AIR RE-ASSERTS ITSELF ACRS THE AREA. BUT THEN LATER TNGT WINDS WL DIE OFF TO NEARLY CALM IN C/N-C WI AS SFC ANTICYCLONE NEARS THE RGN. IN THE END...MAY NOT HAVE A PROLONGED PERIOD OF WIND CHILLS REACHING ADVISORY CRITERIA. BUT IT WL BE CLOSE...SO NOT PLANNING ANY CHANGES TO THE HEADLINE AT THIS POINT. ACTUAL FCST MIN AIR TEMPS...HOWEVER...SEEMED A LITTLE WARM GIVEN STRENGTH OF CAA AND CURRENT TEMPS BACK OUT TO THE W. PLUS...SKIES ARE CLEARING AND SOME AREAS HAVE PROBABLY GOTTEN JUST ENOUGH SNOW FM THE SHSN THIS AFTN/EVE TO IMPACT TEMPS. EDGED MINS DOWN A LITTLE FM PREV FCST. UPDATED PRODUCT SUITE OUT ASAP. SKOWRONSKI && .PREV DISCUSSION...ISSUED AT 523 PM CST WED JAN 23 2013... SHORT TERM...TONIGHT AND THURSDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A COMPACT SHORTWAVE DIVING SOUTHEAST OVER THE ARROWHEAD OF MINNESOTA EARLY THIS AFTERNOON...WHICH IS HELPING TO PUSH ALONG A SURFACE LOW OVER SOUTHERN LAKE SUPERIOR. AHEAD OF THE SHORTWAVE...A COMBINATION OF DPVA AND ISENTROPIC ASCENT IS CONTRIBUTING TO OCCASIONAL LIGHT SNOW ACROSS MUCH OF THE STATE OF WISCONSIN. BEHIND THE SHORTWAVE...ANOTHER SURGE OF ARCTIC AIR IS SLIDING SOUTHEAST...WITH TEMPERATURES FALLING OVER NORTHERN MINNESOTA...AND WINDS GUSTING INTO THE 30-35 MPH RANGE. PLENTY OF CONCERNS IN THE SHORT TERM...INCLUDING LIGHT SNOW...WIND...AND WIND CHILL ISSUES. TONIGHT...THE SHORTWAVE TROUGH WILL BE OVERHEAD AT THE START OF THE EVENING BEFORE DEPARTING BY MIDNIGHT. SOME SNOW SHOWERS ARE DIURNALLY ENHANCED...BUT THINK WILL SEE SNOW SHOWERS LINGER EARLY THIS EVENING WITHIN THE LATEST REINFORCING SURGE OF ARCTIC AIR. BEHIND THE SHORTWAVE...LOW LEVEL WINDS WILL TURN TO THE NNW AND BECOME GUSTY FOR A PERIOD THIS EVENING. COULD SEE SOME GUSTS UP TO 30 MPH. THE WIND DIRECTION WILL ALSO INCREASE LAKE EFFECT POTENTIAL WITHIN THE SNOW BELTS OF N-C WISCONSIN. 850MB TEMPS IN THE MID 20S BELOW ZERO ARE NOT CONDUCIVE FOR GOOD ACCUMULATIONS (TALCUM POWDER SNOW)...BUT UP TO AN INCH OVER THE NW PART OF VILAS COUNTY LOOKS POSSIBLE. POTENTIAL WOULD BE THERE FOR MORE ACCUMS IF THE WIND DIRECTION DIDNT TURN DUE NORTH AFTER MIDNIGHT. ARCTIC HIGH PRESSURE WILL BE BUILDING SE INTO THE WESTERN GREAT LAKES AFTER MIDNIGHT AS WELL WHICH WILL CONTRIBUTE TO CLEARING SKIES. WINDS WILL BE DIMINISHING RATHER QUICKLY AND WILL LIKELY GO LIGHT AND VARIABLE LATE TONIGHT. THIS WILL SET UP CONCERNS FOR WIND CHILL HEADLINES. PROJECTED WIND CHILL VALUES FALL TO 20-25 BELOW BY 02Z OVER CENTRAL AND NORTH-CENTRAL WISCONSIN WHERE THEY WILL REMAIN UNTIL LATE TONIGHT WHEN WINDS DROP OFF. SO THIS SETS UP A WEIRD SCENARIO WHERE WIND CHILLS WILL BE THE COLDEST DURING THE LATE EVENING AND EARLY OVERNIGHT HOURS...BEFORE IMPROVING AS WINDS TURN CALM. WITH COORD FROM OTHER OFFICES...WILL RUN A WIND ADVISORY FROM 02Z THROUGH 12Z THU. POTENTIAL WILL BE THERE TO CANCEL EARLY IF WINDS DO TURN CALM. LOWS FROM 15 BELOW OVER NORTH-CENTRAL WISCONSIN TO AROUND 0 DEGREES NEAR LAKE MICHIGAN. THURSDAY...ARCTIC HIGH PRESSURE WILL BE CENTERED ACROSS THE REGION. ANY LINGERING LAKE EFFECT SNOW SHOWERS WILL BE ENDING THURSDAY MORNING AS WINDS TURN LIGHT AND BACK AROUND TO THE WEST. OTHERWISE WILL SEE A GOOD DEAL OF SUNSHINE. CIRRUS WILL BE INCREASING DURING THE AFTERNOON...BUT MORE SUNSHINE AND LOW LEVEL TEMPS SLIGHTLY WARMER THAN TODAY SHOULD GIVE TEMPS A DEGREE OR TWO WARMER IN MOST LOCATIONS. HIGHS FROM THE UPPER SINGLE DIGITS NORTH TO THE MID TEENS NEAR LAKE MICHIGAN. LONG TERM...THURSDAY NIGHT THROUGH TUESDAY. ALBERTA CLIPPER EXPECTED TO SWING ACROSS THE WESTERN LAKES THURSDAY NIGHT INTO FRIDAY. SNOW IS EXPECTED TO SPREAD INTO NORTHERN MINNESOTA THURSDAY AFTERNOON AND THEN OVERSPREAD THE FORECAST AREA THURSDAY NIGHT. STILL SOME DIFFERENCES WITH THE ONSET OF THE TIMING OF THE SNOW BETWEEN THE GFS/WRF...BUT TRENDED TOWARD THE QUICKER GFS/CANADIAN/ECMWF SOLUTION DUE TO COLD AIR MASS IN PLACE AND QUICKER SATURATION OF THE ATMOSPHERE. WENT WITH SNOW AFTER MIDNIGHT. ACCUMULATIONS SHOULD RANGE FROM 1 TO 3 INCHES ACROSS THE SOUTHWEST TO 2 TO 4 INCHES OVER NORTH-CENTRAL AND NORTHEAST WISCONSIN. WILL NEED TO WATCH DOOR COUNTY AS 925MB WINDS TURN TO THE SOUTH LATE THURSDAY NIGHT INTO FRIDAY MORNING. COULD SEE SOME LAKE EFFECT SNOW SHOWERS/LAKE ENHANCEMENT ACROSS NORTHERN DOOR COUNTY. LIGHT SNOW WILL CONTINUE INTO FRIDAY MORNING BEFORE TAPERING OFF TO SCATTERED SNOW SHOWERS OR FLURRIES FRIDAY AFTERNOON. AROUND AN INCH ADDITIONAL ACCUMULATION IS EXPECTED...BRINGING THE TOTAL STORM ACCUMULATIONS OF 2 TO 4 INCHES ACROSS THE SOUTHWEST PORTION OF THE FORECAST AREA WITH 3 TO 5 INCHES ELSEWHERE. LOCALLY HIGHER AMOUNTS ARE POSSIBLE ACROSS NORTHERN DOOR COUNTY DUE TO LAKE ENHANCEMENT/LAKE EFFECT POTENTIAL. COLDER AIR WILL WORK INTO THE REGION FRIDAY NIGHT. COULD BE SOME GUSTY WINDS BEHIND DEPARTING SYSTEM THAT COULD PRODUCE SOME BLOWING AND DRIFTING SNOW. WILL MENTION IN THE HAZARDOUS WEATHER OUTLOOK. ANOTHER SURGE OF ARCTIC AIR WILL PLUNGE INTO THE AREA BY SATURDAY MORNING WITH TEMPERATURES A FEW DEGREES BELOW ZERO ACROSS CENTRAL WISCONSIN AND NEAR 5 ABOVE ALONG THE LAKE. FORECAST CONFIDENCE WANES QUICKLY SUNDAY INTO THE MIDDLE OF NEXT WEEK. FIRST SYSTEM FOR SUNDAY INTO MONDAY. NEW ECMWF CONTINUES TO BRING BRUNT OF THE SYSTEM SOUTH OF THE AREA WITH ONLY PRECIPITATION UP TO HIGHWAY 29. THE GFS/CANADIAN WOULD SUPPORT AN ACCUMULATING SNOW SUNDAY INTO MONDAY. WILL CONTINUE WITH PREVIOUS FORECAST AS I SUSPECT THE ECMWF WILL SHIFT SYSTEM A LITTLE FURTHER NORTH. THE NEXT SYSTEM EARLY NEXT WEEK CONTINUES TO BE PROBLEMATIC AS WELL. THE CANADIAN/GFS DO NOT BRING SYSTEM UP ALONG THE ARCTIC BOUNDARY. THE 12Z ECMWF WOULD BRING A FAIRLY POTENT SYSTEM FOR MONDAY NIGHT INTO TUESDAY THAT WOULD BRING AN ONSET OF SNOW...FREEZING RAIN BEFORE CHANGING OVER TO RAIN OR FREEZING RAIN. DID NOT INTRODUCE FREEZING RAIN AT THIS TIME SINCE THERE WAS UNCERTAINTY IF THIS STORM WOULD ACTUALLY EXIST. OTHERWISE...ARCTIC AIR IS EXPECTED TO LINGER ALONG THE UNITED STATES/CANADIAN BORDER THROUGH THE END OF NEXT WEEK. HOW MUCH OF THIS ARCTIC INTRUSION WILL FILTER INTO NORTHEAST WISCONSIN IS STILL QUESTIONABLE...BUT IT APPEARS THAT BELOW NORMAL TEMPERATURES CAN BE EXPECTED THROUGH MUCH OF THE PERIOD...EXCEPT FOR THE POSSIBILITY OF TUESDAY IF ECMWF IS CORRECT. && .AVIATION...FOR 00Z TAF ISSUANCE. REINFORCING SHOT OF ARCTIC AIR WL SURGE INTO THE AREA THIS EVENING. THOUGH VFR CONDITIONS WL PREVAIL...SOME VFR/IFR CIGS AND VSBYS WL OCCUR AT TIMES...ESP WITH THE STRONGER SHSN THIS EVENING. ARCTIC HIGH PUSHING ACRS THE STATE WL BRING DECR CLDS AND WINDS BY LATE TNGT. SKOWRONSKI && .GRB WATCHES/WARNINGS/ADVISORIES... WIND CHILL ADVISORY UNTIL 6 AM CST THURSDAY FOR WIZ005-010-011- 018-019-030-035-036. && $$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
523 PM CST WED JAN 23 2013 UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE .SHORT TERM...TONIGHT AND THURSDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A COMPACT SHORTWAVE DIVING SOUTHEAST OVER THE ARROWHEAD OF MINNESOTA EARLY THIS AFTERNOON...WHICH IS HELPING TO PUSH ALONG A SURFACE LOW OVER SOUTHERN LAKE SUPERIOR. AHEAD OF THE SHORTWAVE...A COMBINATION OF DPVA AND ISENTROPIC ASCENT IS CONTRIBUTING TO OCCASIONAL LIGHT SNOW ACROSS MUCH OF THE STATE OF WISCONSIN. BEHIND THE SHORTWAVE...ANOTHER SURGE OF ARCTIC AIR IS SLIDING SOUTHEAST...WITH TEMPERATURES FALLING OVER NORTHERN MINNESOTA...AND WINDS GUSTING INTO THE 30-35 MPH RANGE. PLENTY OF CONCERNS IN THE SHORT TERM...INCLUDING LIGHT SNOW...WIND...AND WIND CHILL ISSUES. TONIGHT...THE SHORTWAVE TROUGH WILL BE OVERHEAD AT THE START OF THE EVENING BEFORE DEPARTING BY MIDNIGHT. SOME SNOW SHOWERS ARE DIURNALLY ENHANCED...BUT THINK WILL SEE SNOW SHOWERS LINGER EARLY THIS EVENING WITHIN THE LATEST REINFORCING SURGE OF ARCTIC AIR. BEHIND THE SHORTWAVE...LOW LEVEL WINDS WILL TURN TO THE NNW AND BECOME GUSTY FOR A PERIOD THIS EVENING. COULD SEE SOME GUSTS UP TO 30 MPH. THE WIND DIRECTION WILL ALSO INCREASE LAKE EFFECT POTENTIAL WITHIN THE SNOW BELTS OF N-C WISCONSIN. 850MB TEMPS IN THE MID 20S BELOW ZERO ARE NOT CONDUCIVE FOR GOOD ACCUMULATIONS (TALCUM POWDER SNOW)...BUT UP TO AN INCH OVER THE NW PART OF VILAS COUNTY LOOKS POSSIBLE. POTENTIAL WOULD BE THERE FOR MORE ACCUMS IF THE WIND DIRECTION DIDNT TURN DUE NORTH AFTER MIDNIGHT. ARCTIC HIGH PRESSURE WILL BE BUILDING SE INTO THE WESTERN GREAT LAKES AFTER MIDNIGHT AS WELL WHICH WILL CONTRIBUTE TO CLEARING SKIES. WINDS WILL BE DIMINISHING RATHER QUICKLY AND WILL LIKELY GO LIGHT AND VARIABLE LATE TONIGHT. THIS WILL SET UP CONCERNS FOR WIND CHILL HEADLINES. PROJECTED WIND CHILL VALUES FALL TO 20-25 BELOW BY 02Z OVER CENTRAL AND NORTH-CENTRAL WISCONSIN WHERE THEY WILL REMAIN UNTIL LATE TONIGHT WHEN WINDS DROP OFF. SO THIS SETS UP A WEIRD SCENARIO WHERE WIND CHILLS WILL BE THE COLDEST DURING THE LATE EVENING AND EARLY OVERNIGHT HOURS...BEFORE IMPROVING AS WINDS TURN CALM. WITH COORD FROM OTHER OFFICES...WILL RUN A WIND ADVISORY FROM 02Z THROUGH 12Z THU. POTENTIAL WILL BE THERE TO CANCEL EARLY IF WINDS DO TURN CALM. LOWS FROM 15 BELOW OVER NORTH-CENTRAL WISCONSIN TO AROUND 0 DEGREES NEAR LAKE MICHIGAN. THURSDAY...ARCTIC HIGH PRESSURE WILL BE CENTERED ACROSS THE REGION. ANY LINGERING LAKE EFFECT SNOW SHOWERS WILL BE ENDING THURSDAY MORNING AS WINDS TURN LIGHT AND BACK AROUND TO THE WEST. OTHERWISE WILL SEE A GOOD DEAL OF SUNSHINE. CIRRUS WILL BE INCREASING DURING THE AFTERNOON...BUT MORE SUNSHINE AND LOW LEVEL TEMPS SLIGHTLY WARMER THAN TODAY SHOULD GIVE TEMPS A DEGREE OR TWO WARMER IN MOST LOCATIONS. HIGHS FROM THE UPPER SINGLE DIGITS NORTH TO THE MID TEENS NEAR LAKE MICHIGAN. .LONG TERM...THURSDAY NIGHT THROUGH TUESDAY. ALBERTA CLIPPER EXPECTED TO SWING ACROSS THE WESTERN LAKES THURSDAY NIGHT INTO FRIDAY. SNOW IS EXPECTED TO SPREAD INTO NORTHERN MINNESOTA THURSDAY AFTERNOON AND THEN OVERSPREAD THE FORECAST AREA THURSDAY NIGHT. STILL SOME DIFFERENCES WITH THE ONSET OF THE TIMING OF THE SNOW BETWEEN THE GFS/WRF...BUT TRENDED TOWARD THE QUICKER GFS/CANADIAN/ECMWF SOLUTION DUE TO COLD AIR MASS IN PLACE AND QUICKER SATURATION OF THE ATMOSPHERE. WENT WITH SNOW AFTER MIDNIGHT. ACCUMULATIONS SHOULD RANGE FROM 1 TO 3 INCHES ACROSS THE SOUTHWEST TO 2 TO 4 INCHES OVER NORTH-CENTRAL AND NORTHEAST WISCONSIN. WILL NEED TO WATCH DOOR COUNTY AS 925MB WINDS TURN TO THE SOUTH LATE THURSDAY NIGHT INTO FRIDAY MORNING. COULD SEE SOME LAKE EFFECT SNOW SHOWERS/LAKE ENHANCEMENT ACROSS NORTHERN DOOR COUNTY. LIGHT SNOW WILL CONTINUE INTO FRIDAY MORNING BEFORE TAPERING OFF TO SCATTERED SNOW SHOWERS OR FLURRIES FRIDAY AFTERNOON. AROUND AN INCH ADDITIONAL ACCUMULATION IS EXPECTED...BRINGING THE TOTAL STORM ACCUMULATIONS OF 2 TO 4 INCHES ACROSS THE SOUTHWEST PORTION OF THE FORECAST AREA WITH 3 TO 5 INCHES ELSEWHERE. LOCALLY HIGHER AMOUNTS ARE POSSIBLE ACROSS NORTHERN DOOR COUNTY DUE TO LAKE ENHANCEMENT/LAKE EFFECT POTENTIAL. COLDER AIR WILL WORK INTO THE REGION FRIDAY NIGHT. COULD BE SOME GUSTY WINDS BEHIND DEPARTING SYSTEM THAT COULD PRODUCE SOME BLOWING AND DRIFTING SNOW. WILL MENTION IN THE HAZARDOUS WEATHER OUTLOOK. ANOTHER SURGE OF ARCTIC AIR WILL PLUNGE INTO THE AREA BY SATURDAY MORNING WITH TEMPERATURES A FEW DEGREES BELOW ZERO ACROSS CENTRAL WISCONSIN AND NEAR 5 ABOVE ALONG THE LAKE. FORECAST CONFIDENCE WANES QUICKLY SUNDAY INTO THE MIDDLE OF NEXT WEEK. FIRST SYSTEM FOR SUNDAY INTO MONDAY. NEW ECMWF CONTINUES TO BRING BRUNT OF THE SYSTEM SOUTH OF THE AREA WITH ONLY PRECIPITATION UP TO HIGHWAY 29. THE GFS/CANADIAN WOULD SUPPORT AN ACCUMULATING SNOW SUNDAY INTO MONDAY. WILL CONTINUE WITH PREVIOUS FORECAST AS I SUSPECT THE ECMWF WILL SHIFT SYSTEM A LITTLE FURTHER NORTH. THE NEXT SYSTEM EARLY NEXT WEEK CONTINUES TO BE PROBLEMATIC AS WELL. THE CANADIAN/GFS DO NOT BRING SYSTEM UP ALONG THE ARCTIC BOUNDARY. THE 12Z ECMWF WOULD BRING A FAIRLY POTENT SYSTEM FOR MONDAY NIGHT INTO TUESDAY THAT WOULD BRING AN ONSET OF SNOW...FREEZING RAIN BEFORE CHANGING OVER TO RAIN OR FREEZING RAIN. DID NOT INTRODUCE FREEZING RAIN AT THIS TIME SINCE THERE WAS UNCERTAINTY IF THIS STORM WOULD ACTUALLY EXIST. OTHERWISE...ARCTIC AIR IS EXPECTED TO LINGER ALONG THE UNITED STATES/CANADIAN BORDER THROUGH THE END OF NEXT WEEK. HOW MUCH OF THIS ARCTIC INTRUSION WILL FILTER INTO NORTHEAST WISCONSIN IS STILL QUESTIONABLE...BUT IT APPEARS THAT BELOW NORMAL TEMPERATURES CAN BE EXPECTED THROUGH MUCH OF THE PERIOD...EXCEPT FOR THE POSSIBILITY OF TUESDAY IF ECMWF IS CORRECT. && .AVIATION...FOR 00Z TAF ISSUANCE. REINFORCING SHOT OF ARCTIC AIR WL SURGE INTO THE AREA THIS EVENING. THOUGH VFR CONDITIONS WL PREVAIL...SOME VFR/IFR CIGS AND VSBYS WL OCCUR AT TIMES...ESP WITH THE STRONGER SHSN THIS EVENING. ARCTIC HIGH PUSHING ACRS THE STATE WL BRING DECR CLDS AND WINDS BY LATE TNGT. SKOWRONSKI && .GRB WATCHES/WARNINGS/ADVISORIES... WIND CHILL ADVISORY UNTIL 6 AM CST THURSDAY FOR WIZ005-010-011- 018-019-030-035-036. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1129 PM CST MON JAN 21 2013 .SHORT TERM...TONIGHT THROUGH THURSDAY 300 PM CST MON JAN 21 2013 MAIN FORECAST CONCERNS ARE ON HOW QUICK THE CURRENT ARCTIC AIRMASS MODIFIES...IF SNOW CAN FORM OFF OF LAKE PEPIN AGAIN TONIGHT...AND LIGHT SNOW CHANCES TUESDAY NIGHT THROUGH THURSDAY. CURRENTLY AS OF 21Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED RIDGING ALONG THE WEST COAST OF THE U.S. INTO BRITISH COLUMBIA...WHILE DEEP TROUGHING WAS IN PLACE OVER SOUTHEAST CANADA INTO THE WESTERN GREAT LAKES REGION. UNDER THIS DEEP TROUGHING... 850MB TEMPS WERE -25C AT MPX...-27C AT GRB AND -35C AT INL PER 12Z SOUNDINGS...OR 2 TO 2.5 STANDARD DEVIATIONS BELOW NORMAL. THESE COLD READINGS...COMBINED WITH A NORTHWEST BREEZE RESULTING FROM A TIGHT PRESSURE GRADIENT BETWEEN LOW PRESSURE IN NORTHERN LAKE HURON AND ARCTIC HIGH PRESSURE IN THE DAKOTAS...HAVE RESULTED IN TEMPERATURES ONLY SLOWLY RISING TODAY. STILL...WITH MOST OF THE AREA EXCLUDING NORTH OF HIGHWAY 10 HAVING BARE GROUND...AND SUNSHINE THROUGH SOME CONVECTIVELY INDUCED STRATOCUMULUS UNDER THE 850MB THERMAL TROUGH HAS ALLOWED TEMPERATURES SOUTH OF HIGHWAY 10 TO CLIMB TO OR SLIGHTLY ABOVE ZERO. WIND CHILLS ARE STILL 15 TO 30 BELOW...THOUGH. TO THE WEST...RAP ANALYSIS SHOWED A 140KT JET AT THE TROPOPAUSE DROPPING DOWN THROUGH THE EASTERN DAKOTAS. ALONG AND WEST OF THIS UPPER JET STREAK...MID AND HIGH CLOUDS ARE PRESENT...REFLECTING THE UPPER LEVEL MOISTURE SEEN ON WATER VAPOR. 850MB TEMPS WARM QUITE A BIT TOO WEST OF THE UPPER JET...AS EXPECTED THROUGH THE THERMAL WIND RELATIONSHIP...CLIMBING FROM -23C AT BIS TO -14C AT UNR PER 12Z SOUNDINGS. TONIGHT AND TUESDAY...THE UPPER LEVEL PATTERN IS NOT FORECAST TO CHANGE MUCH OVER THE NEXT 24 HOURS...WITH PERHAPS ONLY A SLIGHT EASTWARD PROGRESSION TO THE WESTERN RIDGE AND DEEP TROUGH. HOWEVER...THIS PROGRESSION WILL BE ENOUGH TO SLIDE THE ARCTIC HIGH OVER THE DAKOTAS INTO THE FORECAST AREA BY 00Z WEDNESDAY...ALONG WITH THE UPPER JET STREAK AND THE MID/HIGH CLOUDS ACCOMPANYING THE JET STREAK. OF INTEREST TONIGHT IS TO SEE IF ANOTHER NARROW BAND CAN FORM OFF LAKE PEPIN...WHICH WILL DEPEND ON IF THE LAKE WAS ABLE TO FREEZE OVER. LAST NIGHT...WITH THE ARCTIC AIR FLOWING IN...A NARROW BAND FORMED WITH VISIBILITIES LESS THAN 1/4 MILE. SEE OUR NEWS STORY ON OUR WEBSITE FOR MORE ABOUT THE BAND. THE 20.12Z HIRES-ARW YESTERDAY SHOWED THE BAND HAPPENING LAST NIGHT...THOUGH THE THOUGHT AT THE TIME WAS THAT THE ENTIRE MISSISSIPPI RIVER SYSTEM WAS FROZEN OVER. THE 21.06Z/12Z HIRES-ARW SHOW A BAND FORMING AGAIN TONIGHT... AND GIVEN THAT IT HAS STAYED BREEZY TODAY TO HELP PREVENT ICE FORMATION ON LAKE PEPIN...HAVE THUS INCLUDED SOME SMALL PRECIPITATION CHANCES FOR THE BAND BETWEEN 06-15Z TUESDAY. OTHERWISE TEMPERATURES AND WIND CHILLS ARE THE MAIN ISSUE. THE 925MB THERMAL TROUGH REMAINS IN PLACE TONIGHT WITH READINGS OF -24 TO -28C... COLDEST NORTH OF I-94. SINCE WE MAINTAIN A BREEZE MOST OF THE NIGHT...THE BOUNDARY LAYER SHOULD REMAIN MIXED AT LEAST UP TO 950MB IF NOT TO THAT 925MB LEVEL...RESULTING IN LOWS BETWEEN 5 AND 15 BELOW. COLDEST READINGS WOULD OCCUR NORTH OF HIGHWAY 10 WHERE A LITTLE SNOW PACK EXISTS. ON TUESDAY...GRADUAL WARMING TAKES PLACE TO THE 925MB TEMPS WITH THE SHIFT EAST OF THE DEEP TROUGHING...CLIMBING TO -19 TO -23C BY 21Z. THUS...WE SHOULD SEE HIGHS JUST A FEW DEGREES WARMER THAN THOSE TODAY UNDER MOSTLY SUNNY SKIES. TUESDAY NIGHT AND WEDNESDAY...THERE HAS BEEN A TREND TO SLOW UP THE PATTERN MORE DURING THIS TIME PERIOD COMPARED TO PREVIOUS FORECASTS...AND TO SOME DEGREE DRAMATICALLY. THE REASON FOR THE SLOW DOWN IS THAT MODELS HAVE FOCUSED ON A POTENT SHORTWAVE DROPPING SOUTH OUT OF NORTHERN MANITOBA. ALL MODELS HAVE IT DIGGING DOWN INTO UPPER MICHIGAN AND EVEN NORTHERN WISCONSIN BY 00Z THURSDAY. THIS HOLDS UP THE RIDGE OVER THE WESTERN U.S. FROM PUSHING EAST. IN ADDITION...WE END UP NOW SEEING ANOTHER ARCTIC HIGH DROPPING DOWN INTO THE RED RIVER VALLEY OF NORTH DAKOTA...WITH A COLD FRONTAL PASSAGE COMING THROUGH THE FORECAST AREA AHEAD OF IT DURING THE DAY WEDNESDAY. PRIOR TO THIS FRONTAL PASSAGE...THE 21.12Z CANADIAN/UKMET AND 21.00Z ECMWF DEPICT A BAND OF LIGHT QPF COMING INTO THE FORECAST AREA FROM THE WEST...REACHING ABOUT THE MISSISSIPPI RIVER SOUTH OF I-90 BY 12Z WEDNESDAY. THIS BAND IS THAT SAME BAND OF MID/HIGH CLOUDS TRAVERSING THE PLAINS WHICH ENDS UP MARCHING EAST. GIVEN THAT THERE ARE OBSERVATIONS OF SNOW UNDER THE BAND...HAVE MAINTAINED FLURRIES AND INCLUDED 20 PERCENT CHANCES. THE BAND DOES WEAKEN OVER TIME AS THAT POTENT SHORTWAVE DIGS SOUTH...AND AFTER 18Z ANY FLURRIES ASSOCIATED WITH IT SHOULD HAVE SHIFTED OFF TO THE SOUTHEAST. SOME FLURRY ACTIVITY COULD OCCUR NORTH OF I-94 IN THE AFTERNOON WITH THE SHORTWAVE. WITH MORE CLOUDS TUESDAY NIGHT... EXPECT A WARMER NIGHT...AND IN FACT TEMPERATURES COULD RISE AFTER MIDNIGHT AS 925MB TEMPS WARM WITH THE SOUTHWEST WINDS AHEAD OF THE FRONT. THE WARMER NIGHT PLUS 925MB TEMPS OF -12 TO -18C AT 18Z WEDNESDAY SHOULD YIELD HIGHS IN THE TEENS TO LOW 20S IN MOST LOCATIONS. WEDNESDAY NIGHT AND THURSDAY...GOOD AGREEMENT EXISTS AMONG THE 21.12Z GFS/ECMWF/UKMET/CANADIAN OF TAKING A POTENT SHORTWAVE TROUGH COMING INTO THE PACIFIC NORTHWEST AT 00Z THURSDAY ACROSS THE NORTHERN ROCKIES...THEN INTO THE DAKOTAS BY 00Z FRIDAY. AGAIN...THIS IS QUITE A BIT SLOWER THAN YESTERDAYS FORECAST. THE NAM IS AN OUTLIER BY ALMOST BRINGING IT INTO MN...BUT IS NOT DEEP ENOUGH DIGGING THE WEDNESDAY SHORTWAVE. GIVEN THE SLOWER TREND...THE SPREAD OF DPVA AND WARM ADVECTION / FRONTOGENESIS INDUCED SNOW DOWNSTREAM IS SLOWER TOO...WITH DRY CONDITIONS NOW INDICATED THROUGH AT LEAST 18Z THURSDAY FOR THE FORECAST AREA. AFTER 18Z...MODELS CONTINUE TO BACK OFF ON THE AMOUNT OF PRECIPITATION...PRIMARILY BECAUSE THIS POTENT SHORTWAVE TROUGH IS MOISTURE STARVED. ALL THE BETTER MOISTURE IS TIED UP WITH A SOUTHERN STREAM-TYPE SHORTWAVE AND SURFACE LOW PRESSURE SYSTEM OVER THE SOUTHERN PLAINS. THERE STILL IS SOME LIGHT SNOW INDICATED OVER THE AREA PER THE 27.12Z ECMWF...BUT THE 27.12Z GFS IS DRY. THEREFORE...HAVE LOWERED CHANCES ABOUT 10 PERCENT. IF TRENDS CONTINUE...LIKELY THURSDAY WILL END UP DRY WITH JUST SOME INCREASING MID AND HIGH CLOUDS. DUE TO THE DEEPER WEDNESDAY SHORTWAVE TROUGH...HAVE LOWERED LOWS A FEW DEGREES WEDNESDAY NIGHT TO ACCOUNT FOR MORE CANADIAN AIR ADVECTING IN. 925MB TEMPS ACTUALLY FALL TO AROUND -20C BY 12Z THURSDAY. WIND CHILLS LOOK TO STAY OUT OF ADVISORY CRITERIA THIS TIME...THOUGH. WITH MORE CANADIAN AIR IN PLACE ON THURSDAY...ENDING UP ALSO COOLING THURSDAY JUST SLIGHTLY...BUT HAVING BARE GROUND AND A LITTLE MORE SUN WILL HELP COUNTERACT THE COLDER 850MB TEMPS. .LONG TERM...THURSDAY NIGHT THROUGH MONDAY 300 PM CST MON JAN 21 2013 21.12Z ECMWF/CANADIAN/GFS AND ECMWF ENSEMBLES STILL IN PRETTY GOOD AGREEMENT FOR THE LONG TERM FORECAST AND SHOW A SIMILAR SOLUTION TO YESTERDAY. THERE ARE TWO MAIN DIFFERENCES: 1. THE THURSDAY NIGHT DEAL WITH RESPECT TO PRECIPITATION IS NOW LOOKING A LOT LESS THAN WHAT THE 20.12Z ECMWF HAD...SINCE WE ARE ONLY INFLUENCED BY THAT POTENT SHORTWAVE DROPPING THROUGH THE AREA FRIDAY MORNING. ALL OF THE MOISTURE AGAIN IS TIED UP WITH THE SOUTHERN STREAM SYSTEM...SO AT MOST WE END UP WITH A FEW HUNDREDTHS OF LIQUID EQUIVALENT. GIVEN THE POTENT NATURE OF THE TROUGH... DEFINITELY MAINTAINED SOME 30-40 PERCENT CHANCES OF PRECIPITATION FOR THURSDAY NIGHT. FUTURE FORECASTS MAY HAVE TO RAISE THESE SINCE IT IS LOOKING LIKE MOST LOCATIONS SHOULD BE ABLE TO GET A HUNDREDTH. ALSO ADDED SOME LOW CHANCES OF PRECIPITATION TO FRIDAY BEING UNDER THE SHORTWAVE TROUGH TO ALLOW FOR A MORE CONVECTIVE SITUATION. 2. UPPER RIDGING IS STILL PROGGED TO BUILD TOWARDS THE AREA FOR THE WEEKEND...BRINGING TEMPERATURES BACK UP TO NEAR AND EVEN ABOVE NORMAL FOR SUNDAY. HOWEVER...NOW THERE ARE INDICATIONS OF A SHORTWAVE TROUGH MOVING THROUGH THIS RIDGING...IMPACTING THE AREA ON SUNDAY. FOLLOWED THE CONSENSUS AND ADDED 20 PERCENT CHANCES OF SNOW TO THE FORECAST. THIS TROUGH ALSO HOLDS BACK SOME OF THE WARMING THAT WOULD HAVE OCCURRED UNDER THE LOW LEVEL SOUTHWEST FLOW. HEADING INTO MONDAY...MORE TROUGHING IS SUGGESTED ALONG THE WEST COAST OF THE U.S....BUT UNCERTAINTY EXISTS ON WHETHER IT SPLITS INTO TWO AS SHOWN BY THE 21.12Z ECMWF OR STAYS TOGETHER PER 21.12Z GFS. 21.12Z ECMWF ENSEMBLE MEAN SEEMS TO SUGGEST BOTH SCENARIOS ARE PLAUSIBLE. EITHER SCENARIO AT LEAST FOR MONDAY DOES NOT RESULT IN ANY PRECIPITATION FOR US...WITH WARMING COMING BACK INTO THE AREA IN THE WAKE OF THE SUNDAY SHORTWAVE TROUGH. READINGS LOOK LIKE THEY SHOULD GET BACK ABOVE FREEZING FOR HIGHS. && .AVIATION...THROUGH 06Z WEDNESDAY 1129 PM CST MON JAN 21 2013 SIMILIAR CONDITIONS EXPECTED TO CONTINUE WITH MAINLY SCATTERED STRATO CUMULUS WITH BASES BETWEEN 015K-025K FEET THROUGH 00Z WEDNESDAY. WILL LIKELY BE SOME PERIODS OF BROKEN CEILINGS WHICH COULD PRODUCE A FEW FLURRIES. MID LEVEL CLOUDS WILL INCREASE AFTER 00Z. && .ARX WATCHES/WARNINGS/ADVISORIES... 300 PM CST MON JAN 21 2013 WI...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR WIZ017-029- 032>034-041>044-053>055-061. MN...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR MNZ079-086>088- 094>096. IA...WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR IAZ008>011-018- 019-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1022 PM CST MON JAN 21 2013 UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE .PREV DISCUSSION...ISSUED AT 749 PM CST MON JAN 21 2013... UPDATE...THE CORE OF THE COLDEST POOL OF AIR WL MOVE ACROSS THE AREA THIS EVENING...THEN BEGIN EDGING OFF TO THE E LATE TNGT. BUT THERE WL STILL BE SOME NOCTURNAL DROP OFF IN TEMPS TNGT...SO VERY COLD READINGS ARE LIKELY BY TOMORROW MORNING. UNLIKE YDA NGT WHEN SECONDARY PUSH OF CAA LATER IN THE NGT STEEPENED LOW-LEVEL LAPSE RATES AND CAUSED WINDS TO PICK UP LATE AT NGT AND DURING THE EARLY MORNING HRS...THINK WE WL SETTLE INTO A MORE STEADY STATE 7-14 MPH WIND IN MOST AREAS OVERNIGHT. WINDS WL PROBABLY DROP OUT AT TIMES IN SOME OF THE MORE PROTECTED AREAS OF N-C WI. THAT WL PROBABLY CAUSE WIND CHILL INDICES TO BOUNCE ARND SOME...AND THEY AREN/T GOING TO FIT CLEANLY INTO OUR ADVISORY/WARNING CRITERIA AT ALL TIMES. BUT CURRENT HEADLINES SEEM ON TARGET FOR HILIGHTING THE DANGER OF FROSTBITE TO ANYONE GOING OUTDOORS WITHOUT TAKING APPROPRIATE PRECAUTIONS...SO SEE NO REASON TO MAKE ANY CHANGES. UPDATED PRODUCT SUITE OUT ASAP. SKOWRONSKI DISCUSSION ISSUED AT 448 PM CST MON JAN 21 2013... SHORT TERM...TONIGHT AND TUESDAY. THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH PRESSURE STRETCHING SOUTHEAST ACROSS THE GREAT PLAINS EARLY THIS AFTERNOON. WEAK SHORTWAVE IS DROPPING ACROSS THE STATE WHICH IS CONTRIBUTING TO A STRATO-CU FIELD...WITH THE HELP FROM STEEP LOW LEVEL LAPSE RATES. SCT FLURRIES ARE FALLING OUT OF THIS STRATO-CU DECK FROM THE SOUTHERN FOX VALLEY TO CENTRAL AND NORTH-CENTRAL WISCONSIN. TEMPERATURES AND WIND CHILL READINGS HAVE HARDLY BUDGED SINCE EARLIER THIS MORNING...AND PLENTY OF 30-35 BELOW WIND CHILL READINGS REMAIN OVER NORTH-CENTRAL WISCONSIN. FORECAST CONCERNS INCLUDE CLOUD TRENDS AND WIND CHILL HEADLINES. TONIGHT...ARCTIC HIGH PRESSURE WILL BE BUILDING SOUTHEAST ACROSS THE NORTHERN MISSISSIPPI VALLEY THROUGH THE NIGHT. SHORTWAVE TROUGH OVERHEAD WILL BE EXITING THE REGION BY LATE THIS AFTERNOON OR EARLY THIS EVENING. WITH LOSS OF A SMALL DIURNAL COMPONENT...AM COUNTING ON INCREASING SUBSIDENCE TO HELP GRADUALLY DISSIPATE MUCH OF THE STRATO-CU FIELD OVER CENTRAL AND EAST-CENTRAL WISCONSIN THIS EVENING. NORTH-CENTRAL WISCONSIN MAY NOT CLEAR OUT MUCH AT ALL...AS LOW LEVEL WINDS VEER AROUND SLIGHTLY TO THE NORTHWEST AND PUSH LAKE EFFECT CLOUDS SOUTHEAST BENEATH A FAIRLY SHARP INVERSION. TOO COLD FOR MUCH ACCUMS...BUT POSSIBLY UP TO AN INCH OVER THE FAR NORTHERN PART OF THE COUNTY. THE CLEARING SKIES WILL HELP TEMPS BECOME COLDER TONIGHT COMPARED TO LAST NIGHT...BUT THIS WILL BE OFFSET BY A WEAKENING PRESSURE GRADIENT AND WIND SPEEDS. APPARENT TEMP GRIDS SHOW WIND CHILLS FALLING ONLY A FEW DEGREES THIS EVENING...BUT READINGS HAVE REMAINED STEADY ACROSS NORTH-CENTRAL WISCONSIN TODAY...SO WILL NOT TAKE MUCH OF A FALL TO REACH WARNING CRITERIA. AFTER COORDINATING WITH SURROUNDING OFFICES...WILL ISSUE A WIND CHILL WARNING WHERE AM MOST CONFIDENT IN REACHING CRITERIA...FROM LINCOLN AND LANGLADE TO VILAS AND FOREST COUNTY STARTING THIS EVENING AND GOING THROUGH MID-MORNING TUESDAY. TUESDAY...ARCTIC HIGH PRESSURE WILL BE SLIDING TO THE OHIO VALLEY. CORE OF THE COLDEST AIR WILL BE SHIFTING TO THE NORTHEAST...ALONG WITH THE HIGHER LOW LEVEL HUMIDITY. BUT WILL ALREADY BE OFF TO A VERY COLD START SO TEMPS WILL NOT BE SIGNIFICANTLY WARMER THAN TODAYS READINGS. WITH WINDS BACKING TO THE WEST...SHOULD SEE MORE SUNSHINE THAN TODAY. WINDS WILL ALSO BE LIGHTER...AND WIND CHILL READINGS SHOULD BE IMPROVING RAPIDLY BY MID TO LATE MORNING. WILL CONTINUE TO RUN WIND CHILL HEADLINES TO 18Z. HIGHS RANGING FROM 5 BELOW NORTH TO ABOUT 4 ABOVE NEAR LAKE MICHIGAN. LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY. PRIMARY ISSUE CONTINUES TO BE THE DURATION OF THE COLD AIR THIS WEEK FOLLOWED BY A CLIPPER TYPE SYSTEM LATER THIS WEEK. COLD AIR INTRUSION CONTINUES TUESDAY NIGHT WITH THE LIKELY CHANCE OF ADDITIONAL WIND CHILL HEADLINES ACROSS AT LEAST THE NORTH HALF OF THE FORECAST AREA. A WEAK TROUGH IS PROGGED DROPS OVER THE GREAT LAKES REGION IN THE NORTHWEST FLOW WED INTO WED EVENING...FOLLOWED WITH ANOTHER BRIEF PERIOD OF CAA INTO THURSDAY MORNING. THIS BIT LONGER DURATION OF COLDER AIR INTO WEDNESDAY NIGHT PRECEDES THE TREND OF SLOWING DOWN THE CLIPPER TYPE SYSTEM FOR LATER THURSDAY AND INTO FRIDAY MORNING...WHICH IS SUPPORTED BY THE LAST FEW MODEL RUNS. WOULD NOT BE SURPRISED WITH LATER RUNS INDICATING THE CLIPPER WILL LINGER MORE INTO FRIDAY AS THIS CLIPPER SYSTEM PHASES WITH A SOUTHERN STREAM SYSTEM. COULD SEE A FEW INCHES OF SNOW BY FRIDAY OVER MOST LOCATIONS. AFTER A BRIEF PERIOD OF CAA IN THE WAKE OF THE CLIPPER...GRADUALLY MODERATING TEMPERATURES TO NEAR SEASONAL NORMS STILL EXPECTED FOR THE WEEKEND AND INTO MONDAY. WAA FOR SUNDAY ALONG WITH A H850 TROUGH TRACKING OVER THE AREA MAY WILL PROVIDE A CHANCE FOR LIGHT SNOW OR FLURRIES. LAKE EFFECT POTENTIAL. THE CHANCE FOR LAKE EFFECT SNOWS INCREASE TOWARD WEDNESDAY NIGHT OVER FAR NORTHERN WISCONSIN AS THE SHORT WAVE TROUGH SWINGS THROUGH AND WINDS TURN BRIEFLY NORTHWEST AGAIN. NORTHWEST WINDS WILL NOT LAST LONG AS THE COLD SURFACE HIGH DROPS INTO THE REGION. BUT WINDS BEGIN TO TURN MORE EASTERLY THURSDAY INTO THURSDAY NIGHT TO INCREASE THE POTENTIAL OF MORE SNOW SHOWERS ALONG LAKE MICHIGAN..ESPECIALLY AS THE WEAK CLIPPER TRACKS THROUGH TO PROVIDE SOME LIFT. COULD HAVE HIGHER SNOW AMOUNTS ALONG THE LAKE MICHIGAN SHORELINE THURSDAY NIGHT INTO FRIDAY. && .AVIATION...FOR 06Z TAF ISSUANCE. VFR CONDITIONS EXPECTED AS ARCTIC AIR DOMINATES THE AREA. THE ONLY EXCEPTION WL BE NR THE UPPER MICHIGAN BORDER WHERE CLDS OFF LAKE SUPERIOR WL DROP CIGS INTO MVFR CAT AT TIMES. SKOWRONSKI && .GRB WATCHES/WARNINGS/ADVISORIES... WIND CHILL ADVISORY UNTIL NOON CST TUESDAY FOR WIZ012-013- 020>022-030-031-035>040-045-048>050-073-074. WIND CHILL WARNING UNTIL NOON CST TUESDAY FOR WIZ005-010-011-018- 019. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
358 AM CST THU JAN 24 2013 .DISCUSSION... 358 AM CST - - DDHHMM WRKMAR A LOT GOING ON THROUGH THE NEXT 7 DAYS... TODAY... LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z. HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF PRODUCING SOME ACCUMULATING SNOW. HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED. TONIGHT THROUGH FRIDAY... HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST. GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON. WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT 900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800 MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY NIGHT. SUNDAY THROUGH WEDNESDAY... HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55 RFD. MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH 850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT PERIOD OF SLEET/FREEZING RAIN. 00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN. THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID- LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY... THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF THROUGH THE DAY. FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY. WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING 500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * NORTHWEST WINDS GUSTING TO THE MID TEENS EARLY THIS MORNING...THEN VEERING TO THE NORTHEAST AND THEN SOUTHEAST TODAY. * POSSIBILITY FOR LIGHT SNOW/MVFR VIS/MVFR CEILINGS BY MID MORNING TODAY...AND PERSISTING INTO THE EARLY AFTERNOON. * POSSIBILITY FOR LIGHT SNOW AGAIN LATE IN THE PERIOD...EARLY FRIDAY MORNING. RODRIGUEZ //DISCUSSION...UPDATED 06Z... MAIN CONCERNS TODAY WILL BE CENTERED AROUND ONGOING LAKE EFFECT SNOW SHOWERS CURRENTLY PUSHING SOUTH THROUGH NORTHWEST INDIANA. EXPECT THESE SNOW SHOWERS TO PERSIST THIS MORNING INITIALLY AFFECTING GYY IN THE NEAR TERM...WITH VIS DROPPING BELOW 1 MILE AT TIMES. THIS SHOULD AFFECT GYY THROUGH AROUND THE 12Z TIME...WITH THIS SNOW THEN SHIFTING MORE TOWARDS NORTHEAST ILLINOIS. ALTHOUGH THIS SNOW WILL MOVE TOWARDS THE MDW/ORD TERMINALS...EXPECT A SLIGHT DIMINISHING TREND BUT OF MORE IMPORTANCE EXPECT THE MAIN SNOW BAND TO REMAIN JUST EAST OF THE TERMINALS. DESPITE THIS...DO EXPECT VIS OF 3-5SM IN LIGHT SNOW TO BE POSSIBLE FOR ORD/MDW THROUGH MID TO LATE MORNING BEFORE IT CONTINUES TO SHIFT NORTHEAST OUT OF THE AREA. RODRIGUEZ //ORD AND MDW CONFIDENCE...UPDATED 09Z... * HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION. * MEDIUM CONFIDENCE WITH LIGHT SNOW/MVFR VIS/MVFR CEILINGS TRENDS BY MID MORNING. * MEDIUM CONFIDENCE WITH LIGHT SNOW AGAIN LATE IN THE PERIOD. RODRIGUEZ //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...SNOW LIKELY...MAINLY IN THE MORNING...WITH IFR CONDITIONS AND LIGHT SNOW POSSIBLY LINGERING THROUGH THE AFTERNOON. CONDITIONS SHOULD IMPROVE TO VFR IN THE EVENING. SATURDAY...VFR. WX NIL. SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS LIKELY. MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH FREEZING RAIN EARLY...AND POSSIBLY MIXING WITH SNOW OVERNIGHT. MVFR/IFR CONDITIONS LIKELY. TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE. KREIN && .MARINE... 230 PM CST A QUICKLY MIGRATING PATTERN OVER LAKE MICHIGAN THROUGH SATURDAY WILL KEEP WIND SHIFTS AND UPS AND DOWNS IN SPEEDS FREQUENT. A DEVELOPING COLD FRONT WILL MOVE DOWN THE LAKE THIS EVENING AND BECAUSE OF AN IMPEDING STRONG HIGH FROM THE NORTHERN PLAINS...THE PRESSURE GRADIENT RAPIDLY TIGHTENS. WITH CONCURRENT COLD AIR ADVECTION THIS EVENING...NORTHERLY WINDS WILL INCREASE QUICKLY AFTER THE FRONT INCLUDING AT LEAST OCCASIONAL GALES. HAVE OPTED TO GO WITH A GALE WARNING FOR THE SOUTHERN HALF OF THE LAKE FOR THIS...AS THE DURATION LOOKS TO BE SIX TO NINE HOURS OF SUCH WINDS. WITH THE ONSHORE FLOW INTO THE INDIANA SHORE HAVE ALSO GONE WITH A GALE WARNING FOR THERE. THE COMBINATION OF THESE WINDS AND THE FALLING TEMPERATURES WILL OFFER A MODERATE FREEZING SPRAY THREAT TONIGHT. THEN A BRIEF PERIOD OF HIGH PRESSURE WILL PREVAIL BEFORE THE NEXT LOW PRESSURE APPROACHING THURSDAY NIGHT AND MOVING PAST BY LATER FRIDAY. THIS WILL HAVE MODEST SOUTHERLY FLOW AHEAD OF IT DUE AGAIN TO THE STRONG PRESSURE GRADIENT SET UP BY THE QUICK MOVING PATTERN. AFTER ANOTHER HIGH PRESSURE SATURDAY THE PATTERN SHIFTS SOMEWHAT ALLOWING LOW PRESSURES TO APPROACH THE LAKE FROM THE SOUTHWEST. A SOMEWHAT WEAK LOW IS PROJECTED ON SUNDAY NIGHT INTO MONDAY BEFORE A STRONG ONE DURING MIDWEEK. ALL THIS WILL LIKELY MEAN SOUTHERLY FLOW...ESPECIALLY LATER MONDAY THROUGH TUESDAY. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...LAKE EFFECT SNOW ADVISORY...INZ001-INZ002 UNTIL NOON THURSDAY. LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM THURSDAY. GALE WARNING...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM THURSDAY. SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 PM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
403 AM EST THU JAN 24 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 338 AM EST THU JAN 24 2013 HIGH PRESSURE WILL BRING DRY CHILLY WEATHER TO CENTRAL INDIANA TODAY. LOW PRESSURE WILL TRACK THROUGH THE GREAT LAKES ON FRIDAY...WITH SNOW DEVELOPING LATE TONIGHT AND CONTINUING THROUGH FRIDAY AFTERNOON. A MORE ACTIVE WEATHER PATTERN ARRIVES BEGINNING SUNDAY AND CONTINUING INTO NEXT WEEK AS A WARM FRONT LIFTS INTO THE REGION WITH SEVERAL DISTURBANCES TRACKING ALONG IT. AFTER THE POTENTIAL FOR A WINTRY MIX SUNDAY AFTERNOON AND NIGHT...TEMPERATURES WILL BE WARM ENOUGH FOR RAIN FOR MUCH OF NEXT WEEK. && .NEAR TERM /TODAY/... ISSUED AT 338 AM EST THU JAN 24 2013 LAKE EFFECT SNOW SHOWERS AND FLURRIES CONTINUE TO MOVE SOUTH INTO THE NORTHERN HALF OF THE FORECAST AREA EARLY THIS MORNING. OUTSIDE OF SNOW SHOWERS/FLURRIES...SKIES WERE PARTLY CLOUDY AS HIGH PRESSURE BEGINNING TO EXPAND INTO THE REGION. TEMPS WERE FALLING THROUGH THE 20S AND INTO THE TEENS AS COLD ADVECTION ESTABLISHES. INITIAL FOCUS OF THE NEAR TERM IS ON THE TRANSIENT NATURE OF THE SNOW SHOWERS AND FLURRIES COMING OUT OF NORTHERN INDIANA AND INTO NORTHERN COUNTIES. LOW LEVEL FLOW VIA THE MOST RECENT RAP DATA REMAINS FROM THE NORTHWEST WITH THE VAD PROFILE OFF OF THE KIND RADAR INDICATING 25-30KTS PRESENT AT ABOUT 3KFT. HAVE SEEN POCKETS OF HEAVIER SNOW SHOWERS WITHIN A BAND EXTENDING FROM LOGANSPORT SOUTHEAST THROUGH KOKOMO TO NEAR NOBLESVILLE. EXPECT THESE SNOW SHOWERS/FLURRIES TO SHIFT WEST AND WEAKEN AS THEY DROP SOUTH WITH BOUNDARY LAYER FLOW SET TO VEER TO A MORE NORTHERLY DIRECTION THROUGH DAYBREAK. THERE ARE SIGNS THIS SHIFT IN LOW LEVEL FLOW IS ALREADY BEGINNING AS AN INCREASINGLY DOMINANT SNOW BAND DEVELOPING DUE SOUTH OFF OF LAKE MICHIGAN OVER LAKE AND PORTER COS. POTENTIAL REMAINS FOR THE OUTER FRINGES OF THIS BAND TO WORK ALL THE WAY SOUTH INTO CARROLL AND TIPPECANOE COS AFTER 09Z AND THROUGH DAYBREAK BEFORE LOW LEVEL FLOW VEERS FURTHER AND WEAKENS. HAVE HELD ONTO LOW CHANCE POPS FOR THE NEXT FEW HOURS TO ACCOUNT FOR ONGOING SNOW SHOWERS...THEN REFOCUSED IT OVER THE NORTHERN WABASH VALLEY TO ENCOMPASS ABOVE THOUGHTS. COULD SEE A DUSTING IN LOCALIZED AREAS OVER THE NEXT FEW HOURS TO THE NORTH OF INDY...BUT WITH A DRY SNOW MOST WILL BE BLOWN AROUND MORE THAN ANYTHING ELSE. BROAD CANADIAN HIGH PRESSURE WILL THEN TAKE OVER FOR THE REMAINDER OF THE SHORT TERM...WITH ANOTHER SURGE OF DRY ARCTIC AIR SPREADING ACROSS THE REGION. DEEP SUBSIDENCE EXPANDING INTO THE BOUNDARY LAYER WILL LEAD TO MOSTLY SUNNY SKIES THROUGH MIDDAY...WITH A SLOW EXPANSION IN MID AND HIGH LEVEL CLOUDS BY LATE AFTERNOON AS MOISTURE ALOFT SPREADS INTO THE REGION FROM THE NORTHWEST. WIND GUSTS THIS MORNING SHOULD DROP OFF RATHER QUICKLY AS THE CENTER OF THE HIGH MOVES ACROSS THE REGION THIS AFTERNOON. TEMPS...COLD ADVECTION THROUGH THE AFTERNOON WILL KEEP IT CHILLY... WITH LOW LEVEL THERMALS SUPPORTING MOS TEMPS IN THE LOWER TO MID 20S. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... ISSUED AT 338 AM EST THU JAN 24 2013 FORECAST CHALLENGES FOCUS ON SNOW CHANCES LATE TONIGHT THROUGH FRIDAY AS LOW PRESSURE DROPS THROUGH THE GREAT LAKES. STILL SOME DISCREPANCIES BETWEEN MODELS WITH RESPECT TO MOISTURE AVAILABILITY AND FORCING ASSOCIATED WITH THE SURFACE WAVE...BUT OVERALL GUIDANCE IN BETTER AGREEMENT THIS MORNING ON THE MAIN FEATURES. CLOUDS WILL INCREASE TONIGHT AS THE WAVE APPROACHES FROM THE NORTHWEST AS ISENTROPIC LIFT AND MOISTURE DEVELOP ALONG A BOUNDARY OVER THE TENNESSEE VALLEY. SUSPECT MOISTENING OF THE LOWER LEVELS WILL TAKE SOME TIME AND EFFORT AFTER MIDNIGHT AS SURFACE FLOW DIRECTION VEERS ONLY SLOWLY FROM EASTERLY TO A MORE S/SE DIRECTION BY 12Z FRIDAY. HAVE DELAYED ONSET OF POPS UNTIL LATE TONIGHT WITH THE INITIAL VERY DRY BOUNDARY LAYER. STILL HAVE QUESTIONS AS TO THE DEPTH OF THE MOISTURE THAT WILL ACCOMPANY THE SYSTEM...AS NO STRONG GULF FEED WILL BE PRESENT WITH BOUNDARY LAYER WINDS SHIFTING MORE TO A W/SW FLOW. BRIEF PERIOD OF ISENTROPIC LIFT DEVELOPS JUST PRIOR TO DAYBREAK AND EXTENDS THROUGH THE MORNING FRIDAY BEFORE MOISTURE AND MORE SUBSTANTIAL LIFT SHIFTS EAST INTO THE AFTERNOON. MODEL SOUNDINGS CONTINUE TO SHOW PRECIP FALLING AS ALL SNOW ACROSS THE FORECAST AREA...ALTHOUGH HINTS OF A THIN LAYER OF ABOVE FREEZING AIR IN THE BOUNDARY LAYER BRIEFLY COMING INTO SOUTHERN INDIANA FRIDAY MORNING HAVE RETURNED. FOCUS OF HEAVIEST SNOWFALL FRIDAY MORNING SHOULD SET UP OVER THE NORTHEAST HALF OF THE FORECAST AREA WHERE AXIS OF STRONGEST ISENTROPIC LIFT COMBINES WITH A PERIOD WITH GREATER VERTICAL VELOCITIES AND A SLIGHTLY DEEPER DENDRITIC GROWTH ZONE. WITH SNOW RATIOS LIKELY TO BE ELEVATED AND CLOSER TO 15 TO 1 IN THESE AREAS...FEEL COMFORTABLE PLACING A GENERAL 1 TO 2 INCHES THROUGH FRIDAY AFTERNOON NORTHEAST OF A ROCKVILLE-MARTINSVILLE- COLUMBUS LINE WITH AMOUNTS DROPPING OFF QUICKLY TO THE SOUTH OF THAT LINE. OP GFS EVEN HINTS AT DEVELOPMENT OF A TROWAL OVER OHIO FRIDAY MORNING WHICH MAY SERVE TO ENHANCE LIFT EVEN A TOUCH MORE OVER NORTHEAST COUNTIES AND ENABLE A FEW SPOTS FROM KOKOMO TO MUNCIE AND WINCHESTER TO MAKE A RUN AT 2 TO 3 INCHES FOR A FINAL TALLY. DRIER AIR WILL ADVECT INTO THE REGION FROM THE WEST RATHER QUICKLY ON FRIDAY AFTERNOON...SHUTTING OFF LIGHT SNOW FOR MOST OF THE REGION AND POTENTIALLY EVEN LEADING TO SOME CLEARING LATE. HAVE HELD ONTO LOW CHANCE POPS HOWEVER THROUGH THE REST OF THE AFTERNOON OVER NORTHEAST HALF OF THE FORECAST AREA AS A SECONDARY WAVE ALOFT DROPS THROUGH THE LOWER GREAT LAKES WITH THE SURFACE LOW AND MAY SERVE TO MAINTAIN SCATTERED LIGHT SNOW SHOWERS OR FLURRIES. ANY LINGERING FLURRIES WILL END OVER NORTHEAST COUNTIES FRIDAY EVENING WITH HIGH PRESSURE REESTABLISHING OVER THE REGION FOR THE REMAINDER OF THE SHORT TERM. THE HIGH WILL BRING ANOTHER SHOT OF COLDER AIR FOR FRIDAY NIGHT AND SATURDAY...BUT WARM ADVECTION WILL COMMENCE SATURDAY NIGHT AS THE HIGH MOVES OFF TO THE EAST AND RIDGING ALOFT EXPANDS INTO THE OHIO VALLEY. MID AND HIGH LEVEL CLOUD COVER WILL INCREASE LATE SATURDAY NIGHT AS LOW PRESSURE AND AN ASSOCIATED WARM FRONT LIFTS OUT OF THE CENTRAL PLAINS. TEMPS...PREFERRED COOLER METMOS GUIDANCE FOR HIGHS FRIDAY AS CLOUDS AND PRECIP FOR MUCH OF THE DAY FOLLOWED BY COLD ADVECTION. MAVMOS LOOKED REASONABLE FOR HIGHS SATURDAY PRIMARILY IN THE MID AND UPPER 20S. TRENDED TOWARDS MAVMOS FOR LOWS TONIGHT...THEN GENERALLY WENT AT OR A COUPLE DEGREES BELOW GUIDANCE FOR FRI/SAT NIGHTS CONSIDERING MAY HAVE A THIN SNOW COVER IN SOME SPOTS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... ISSUED AT 327 AM EST THU JAN 24 2013 AN ACTIVE WEATHER PATTERN SETS UP IN THE LONG TERM WITH AN UPPER TROUGH MOVING THROUGH THE PACIFIC NORTHWEST INTO THE CENTRAL U.S. THROUGH THE PERIOD. A SERIES OF UPPER SHORTWAVES WILL EJECT FROM THE UPPER TROUGH AND BRING CHANCES FOR PRECIPITATION TO THE AREA. AT THE SURFACE A WARM FRONT WILL FORM SOUTH OF THE AREA AND SLOWLY MOVE NORTH BEFORE THE SURFACE LOW EJECTS FROM THE PLAINS AND TRAVERSES THE GREAT LAKES. MODELS HAVE SOME MINOR DISAGREEMENTS IN TIMING/TEMPERATURES EARLY WITH SIGNIFICANT DIFFERENCES BY TUESDAY NIGHT. GENERALLY ACCEPTED ALLBLEND INITIALIZATION. BIGGEST CHALLENGE WILL BE PRECIPITATION TYPE FOR SUNDAY-MONDAY. ENTIRE COLUMN IS BELOW FREEZING SUNDAY MORNING BEFORE PRECIPITATION ARRIVES. BY SUNDAY AFTERNOON WITH UPPER SHORTWAVE APPROACHING ECMWF AND GFS SHOW AN INTRUSION OF WARM AIR ALOFT INTO THE SOUTHWEST AND BY SUNDAY NIGHT THIS MOVES ALL ACROSS THE AREA. MOST OF THE AREA SHOULD SEE A PROGRESSION FROM A CHANCE FOR SNOW TO A CHANCE FOR SNOW AND SLEET TO A CHANCE FOR FREEZING RAIN AND SLEET BEFORE TRANSITIONING TO RAIN. TRIED TO MATCH TRANSITION UP WITH FORECAST SOUNDINGS AND PARTIAL THICKNESSES...BUT BOTTOM LINE IS MUCH OF THE AREA WILL SEE SOME TYPE OF WINTRY MIX BEFORE THE TRANSITION TO ALL RAIN WHICH SHOULD OCCUR BY SOMETIME MONDAY MORNING. THEN CHANCES FOR RAIN WILL BE THE RULE UNTIL WEDNESDAY WHEN PRECIP TYPE IS UP IN THE AIR BECAUSE OF AFOREMENTIONED SIGNIFICANT MODEL TEMPERATURE DIFFERENCES. ANOTHER ITEM OF NOTE IS THE STRENGTH OF THE SYSTEM EJECTING FROM THE PLAINS TUESDAY/TUESDAY NIGHT. IF THE VERY WARM GFS WERE TO VERIFY COULD SEE CHANCES FOR THUNDER EEK THIS FAR NORTH. WILL LEAVE OUT FOR NOW AS ECMWF PAINTS A MUCH DIFFERENT PICTURE AND WOULD RATHER HAVE SOME AGREEMENT TO INCLUDE THUNDER THIS TIME OF YEAR. && .AVIATION /DISCUSSION FOR THE 24/09Z TAF UPDATE/... ISSUED AT 403 AM EST THU JAN 24 2013 A FEW BANDS OF LAKE EFFECT SNOW SHOWERS REMAIN ACROSS THE AREA AND CLOUDS WITHIN THESE BANDS HAVE CEILINGS IN THE 025-035 FT RANGE. AT THIS TIME RADAR TRENDS INDICATE POTENTIAL TO IMPACT KBMG AND PERHAPS CLIP KIND OVER THE NEXT COUPLE HOURS. KLAF COULD GET TAPPED WITH ANOTHER BAND CURRENTLY COMING OFF THE LAKE...BUT THEY MAY NOT HOLD TOGETHER THAT FAR SOUTH AS THE WIND SHIFTS. THEREFORE JUST INCLUDED A TEMPO MVFR GROUP AT KBMG. WIND GUSTS HAVE COME TO AN END AND SO REMOVED THEM. EXPECT THEM TO VEER TO NORTHEASTERLY THIS MORNING. CLOUDS WILL FILL IN AGAIN BY EVENING AHEAD OF THE NEXT SYSTEM. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM....CP AVIATION...CP
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
338 AM EST THU JAN 24 2013 .UPDATE... THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 338 AM EST THU JAN 24 2013 HIGH PRESSURE WILL BRING DRY CHILLY WEATHER TO CENTRAL INDIANA TODAY. LOW PRESSURE WILL TRACK THROUGH THE GREAT LAKES ON FRIDAY...WITH SNOW DEVELOPING LATE TONIGHT AND CONTINUING THROUGH FRIDAY AFTERNOON. A MORE ACTIVE WEATHER PATTERN ARRIVES BEGINNING SUNDAY AND CONTINUING INTO NEXT WEEK AS A WARM FRONT LIFTS INTO THE REGION WITH SEVERAL DISTURBANCES TRACKING ALONG IT. AFTER THE POTENTIAL FOR A WINTRY MIX SUNDAY AFTERNOON AND NIGHT...TEMPERATURES WILL BE WARM ENOUGH FOR RAIN FOR MUCH OF NEXT WEEK. && .NEAR TERM /TODAY/... ISSUED AT 338 AM EST THU JAN 24 2013 LAKE EFFECT SNOW SHOWERS AND FLURRIES CONTINUE TO MOVE SOUTH INTO THE NORTHERN HALF OF THE FORECAST AREA EARLY THIS MORNING. OUTSIDE OF SNOW SHOWERS/FLURRIES...SKIES WERE PARTLY CLOUDY AS HIGH PRESSURE BEGINNING TO EXPAND INTO THE REGION. TEMPS WERE FALLING THROUGH THE 20S AND INTO THE TEENS AS COLD ADVECTION ESTABLISHES. INITIAL FOCUS OF THE NEAR TERM IS ON THE TRANSIENT NATURE OF THE SNOW SHOWERS AND FLURRIES COMING OUT OF NORTHERN INDIANA AND INTO NORTHERN COUNTIES. LOW LEVEL FLOW VIA THE MOST RECENT RAP DATA REMAINS FROM THE NORTHWEST WITH THE VAD PROFILE OFF OF THE KIND RADAR INDICATING 25-30KTS PRESENT AT ABOUT 3KFT. HAVE SEEN POCKETS OF HEAVIER SNOW SHOWERS WITHIN A BAND EXTENDING FROM LOGANSPORT SOUTHEAST THROUGH KOKOMO TO NEAR NOBLESVILLE. EXPECT THESE SNOW SHOWERS/FLURRIES TO SHIFT WEST AND WEAKEN AS THEY DROP SOUTH WITH BOUNDARY LAYER FLOW SET TO VEER TO A MORE NORTHERLY DIRECTION THROUGH DAYBREAK. THERE ARE SIGNS THIS SHIFT IN LOW LEVEL FLOW IS ALREADY BEGINNING AS AN INCREASINGLY DOMINANT SNOW BAND DEVELOPING DUE SOUTH OFF OF LAKE MICHIGAN OVER LAKE AND PORTER COS. POTENTIAL REMAINS FOR THE OUTER FRINGES OF THIS BAND TO WORK ALL THE WAY SOUTH INTO CARROLL AND TIPPECANOE COS AFTER 09Z AND THROUGH DAYBREAK BEFORE LOW LEVEL FLOW VEERS FURTHER AND WEAKENS. HAVE HELD ONTO LOW CHANCE POPS FOR THE NEXT FEW HOURS TO ACCOUNT FOR ONGOING SNOW SHOWERS...THEN REFOCUSED IT OVER THE NORTHERN WABASH VALLEY TO ENCOMPASS ABOVE THOUGHTS. COULD SEE A DUSTING IN LOCALIZED AREAS OVER THE NEXT FEW HOURS TO THE NORTH OF INDY...BUT WITH A DRY SNOW MOST WILL BE BLOWN AROUND MORE THAN ANYTHING ELSE. BROAD CANADIAN HIGH PRESSURE WILL THEN TAKE OVER FOR THE REMAINDER OF THE SHORT TERM...WITH ANOTHER SURGE OF DRY ARCTIC AIR SPREADING ACROSS THE REGION. DEEP SUBSIDENCE EXPANDING INTO THE BOUNDARY LAYER WILL LEAD TO MOSTLY SUNNY SKIES THROUGH MIDDAY...WITH A SLOW EXPANSION IN MID AND HIGH LEVEL CLOUDS BY LATE AFTERNOON AS MOISTURE ALOFT SPREADS INTO THE REGION FROM THE NORTHWEST. WIND GUSTS THIS MORNING SHOULD DROP OFF RATHER QUICKLY AS THE CENTER OF THE HIGH MOVES ACROSS THE REGION THIS AFTERNOON. TEMPS...COLD ADVECTION THROUGH THE AFTERNOON WILL KEEP IT CHILLY... WITH LOW LEVEL THERMALS SUPPORTING MOS TEMPS IN THE LOWER TO MID 20S. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... ISSUED AT 338 AM EST THU JAN 24 2013 FORECAST CHALLENGES FOCUS ON SNOW CHANCES LATE TONIGHT THROUGH FRIDAY AS LOW PRESSURE DROPS THROUGH THE GREAT LAKES. STILL SOME DISCREPANCIES BETWEEN MODELS WITH RESPECT TO MOISTURE AVAILABILITY AND FORCING ASSOCIATED WITH THE SURFACE WAVE...BUT OVERALL GUIDANCE IN BETTER AGREEMENT THIS MORNING ON THE MAIN FEATURES. CLOUDS WILL INCREASE TONIGHT AS THE WAVE APPROACHES FROM THE NORTHWEST AS ISENTROPIC LIFT AND MOISTURE DEVELOP ALONG A BOUNDARY OVER THE TENNESSEE VALLEY. SUSPECT MOISTENING OF THE LOWER LEVELS WILL TAKE SOME TIME AND EFFORT AFTER MIDNIGHT AS SURFACE FLOW DIRECTION VEERS ONLY SLOWLY FROM EASTERLY TO A MORE S/SE DIRECTION BY 12Z FRIDAY. HAVE DELAYED ONSET OF POPS UNTIL LATE TONIGHT WITH THE INITIAL VERY DRY BOUNDARY LAYER. STILL HAVE QUESTIONS AS TO THE DEPTH OF THE MOISTURE THAT WILL ACCOMPANY THE SYSTEM...AS NO STRONG GULF FEED WILL BE PRESENT WITH BOUNDARY LAYER WINDS SHIFTING MORE TO A W/SW FLOW. BRIEF PERIOD OF ISENTROPIC LIFT DEVELOPS JUST PRIOR TO DAYBREAK AND EXTENDS THROUGH THE MORNING FRIDAY BEFORE MOISTURE AND MORE SUBSTANTIAL LIFT SHIFTS EAST INTO THE AFTERNOON. MODEL SOUNDINGS CONTINUE TO SHOW PRECIP FALLING AS ALL SNOW ACROSS THE FORECAST AREA...ALTHOUGH HINTS OF A THIN LAYER OF ABOVE FREEZING AIR IN THE BOUNDARY LAYER BRIEFLY COMING INTO SOUTHERN INDIANA FRIDAY MORNING HAVE RETURNED. FOCUS OF HEAVIEST SNOWFALL FRIDAY MORNING SHOULD SET UP OVER THE NORTHEAST HALF OF THE FORECAST AREA WHERE AXIS OF STRONGEST ISENTROPIC LIFT COMBINES WITH A PERIOD WITH GREATER VERTICAL VELOCITIES AND A SLIGHTLY DEEPER DENDRITIC GROWTH ZONE. WITH SNOW RATIOS LIKELY TO BE ELEVATED AND CLOSER TO 15 TO 1 IN THESE AREAS...FEEL COMFORTABLE PLACING A GENERAL 1 TO 2 INCHES THROUGH FRIDAY AFTERNOON NORTHEAST OF A ROCKVILLE-MARTINSVILLE- COLUMBUS LINE WITH AMOUNTS DROPPING OFF QUICKLY TO THE SOUTH OF THAT LINE. OP GFS EVEN HINTS AT DEVELOPMENT OF A TROWAL OVER OHIO FRIDAY MORNING WHICH MAY SERVE TO ENHANCE LIFT EVEN A TOUCH MORE OVER NORTHEAST COUNTIES AND ENABLE A FEW SPOTS FROM KOKOMO TO MUNCIE AND WINCHESTER TO MAKE A RUN AT 2 TO 3 INCHES FOR A FINAL TALLY. DRIER AIR WILL ADVECT INTO THE REGION FROM THE WEST RATHER QUICKLY ON FRIDAY AFTERNOON...SHUTTING OFF LIGHT SNOW FOR MOST OF THE REGION AND POTENTIALLY EVEN LEADING TO SOME CLEARING LATE. HAVE HELD ONTO LOW CHANCE POPS HOWEVER THROUGH THE REST OF THE AFTERNOON OVER NORTHEAST HALF OF THE FORECAST AREA AS A SECONDARY WAVE ALOFT DROPS THROUGH THE LOWER GREAT LAKES WITH THE SURFACE LOW AND MAY SERVE TO MAINTAIN SCATTERED LIGHT SNOW SHOWERS OR FLURRIES. ANY LINGERING FLURRIES WILL END OVER NORTHEAST COUNTIES FRIDAY EVENING WITH HIGH PRESSURE REESTABLISHING OVER THE REGION FOR THE REMAINDER OF THE SHORT TERM. THE HIGH WILL BRING ANOTHER SHOT OF COLDER AIR FOR FRIDAY NIGHT AND SATURDAY...BUT WARM ADVECTION WILL COMMENCE SATURDAY NIGHT AS THE HIGH MOVES OFF TO THE EAST AND RIDGING ALOFT EXPANDS INTO THE OHIO VALLEY. MID AND HIGH LEVEL CLOUD COVER WILL INCREASE LATE SATURDAY NIGHT AS LOW PRESSURE AND AN ASSOCIATED WARM FRONT LIFTS OUT OF THE CENTRAL PLAINS. TEMPS...PREFERRED COOLER METMOS GUIDANCE FOR HIGHS FRIDAY AS CLOUDS AND PRECIP FOR MUCH OF THE DAY FOLLOWED BY COLD ADVECTION. MAVMOS LOOKED REASONABLE FOR HIGHS SATURDAY PRIMARILY IN THE MID AND UPPER 20S. TRENDED TOWARDS MAVMOS FOR LOWS TONIGHT...THEN GENERALLY WENT AT OR A COUPLE DEGREES BELOW GUIDANCE FOR FRI/SAT NIGHTS CONSIDERING MAY HAVE A THIN SNOW COVER IN SOME SPOTS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... ISSUED AT 327 AM EST THU JAN 24 2013 AN ACTIVE WEATHER PATTERN SETS UP IN THE LONG TERM WITH AN UPPER TROUGH MOVING THROUGH THE PACIFIC NORTHWEST INTO THE CENTRAL U.S. THROUGH THE PERIOD. A SERIES OF UPPER SHORTWAVES WILL EJECT FROM THE UPPER TROUGH AND BRING CHANCES FOR PRECIPITATION TO THE AREA. AT THE SURFACE A WARM FRONT WILL FORM SOUTH OF THE AREA AND SLOWLY MOVE NORTH BEFORE THE SURFACE LOW EJECTS FROM THE PLAINS AND TRAVERSES THE GREAT LAKES. MODELS HAVE SOME MINOR DISAGREEMENTS IN TIMING/TEMPERATURES EARLY WITH SIGNIFICANT DIFFERENCES BY TUESDAY NIGHT. GENERALLY ACCEPTED ALLBLEND INITIALIZATION. BIGGEST CHALLENGE WILL BE PRECIPITATION TYPE FOR SUNDAY-MONDAY. ENTIRE COLUMN IS BELOW FREEZING SUNDAY MORNING BEFORE PRECIPITATION ARRIVES. BY SUNDAY AFTERNOON WITH UPPER SHORTWAVE APPROACHING ECMWF AND GFS SHOW AN INTRUSION OF WARM AIR ALOFT INTO THE SOUTHWEST AND BY SUNDAY NIGHT THIS MOVES ALL ACROSS THE AREA. MOST OF THE AREA SHOULD SEE A PROGRESSION FROM A CHANCE FOR SNOW TO A CHANCE FOR SNOW AND SLEET TO A CHANCE FOR FREEZING RAIN AND SLEET BEFORE TRANSITIONING TO RAIN. TRIED TO MATCH TRANSITION UP WITH FORECAST SOUNDINGS AND PARTIAL THICKNESSES...BUT BOTTOM LINE IS MUCH OF THE AREA WILL SEE SOME TYPE OF WINTRY MIX BEFORE THE TRANSITION TO ALL RAIN WHICH SHOULD OCCUR BY SOMETIME MONDAY MORNING. THEN CHANCES FOR RAIN WILL BE THE RULE UNTIL WEDNESDAY WHEN PRECIP TYPE IS UP IN THE AIR BECAUSE OF AFOREMENTIONED SIGNIFICANT MODEL TEMPERATURE DIFFERENCES. ANOTHER ITEM OF NOTE IS THE STRENGTH OF THE SYSTEM EJECTING FROM THE PLAINS TUESDAY/TUESDAY NIGHT. IF THE VERY WARM GFS WERE TO VERIFY COULD SEE CHANCES FOR THUNDER EEK THIS FAR NORTH. WILL LEAVE OUT FOR NOW AS ECMWF PAINTS A MUCH DIFFERENT PICTURE AND WOULD RATHER HAVE SOME AGREEMENT TO INCLUDE THUNDER THIS TIME OF YEAR. && .AVIATION /DISCUSSION FOR THE 24/06Z TAF ISSUANCE/... ISSUED AT 1148 PM EST WED JAN 23 2013 WINDS ARE STARTING TO STRENGTHEN AND BECOME NORTHWESTERLY ON THE BACK SIDE OF A GREAT LAKES DISTURBANCE. ANY SNOW SHOWERS ASSOCIATED WITH THE LOW HAVE EXITED THE AREA. HOWEVER...WILL LEAVE MENTION OF SNOW SHOWERS AT KLAF TONIGHT WITH THE PERFECT SET UP FOR LAKE EFFECT. DO NOT EXPECT CONDITIONS TO FALL BELOW VFR CATEGORY THOUGH. WINDS WILL WEAKEN AROUND MID MORNING TOMORROW AND TAKE ON MORE OF A NORTHEASTERLY COMPONENT. CLOUDS WILL BREAK UP BRIEFLY TOMORROW AFTERNOON...AND THEN FILL IN AGAIN BY EVENING AHEAD OF THE NEXT SYSTEM. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM....CP AVIATION...TDUD
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1242 AM EST THU JAN 24 2013 .AVIATION... 06Z TAFS...A BRIEF LULL IN HEAVIER SNOW SHOWERS AT KSBN...BUT UPSTREAM RADAR TRENDS SUGGEST MORE ORGANIZED LAKE EFFECT SNOW BAND ALONG EASTERN SHORE OF LAKE MICHIGAN WILL AFFECT KSBN IN THE 07Z- 09Z TIMEFRAME. PERIODS OF LIFR VSBY RESTRICTIONS ARE LIKELY WITH THIS BAND...WITH HEAVIEST SNOW LIKELY SHIFTING WEST OF THE TERMINAL AFTER 09Z. A BRIEF BURST OF HEAVIER SNOW EXPECTED AT KFWA OVER THE NEXT HOUR...BUT BY 07Z ALL OF LAKE EFFECT SNOW SHOULD REMAIN SOUTH AND WEST OF THE TERMINAL. LINGERING MVFR CIGS AT KSBN SHOULD SCATTER BY MID MORNING. QUIET AVIATION WEATHER WILL SET UP FOR THE REMAINDER OF THIS PERIOD WITH STRONG SUBSIDENCE IN WAKE OF SYNOPTIC TROUGH. STRONG MID LEVEL WARM ADVECTION IN ADVANCE OF NEXT UPPER TROUGH WILL ALLOW MID LEVEL CIGS TO OVERSPREAD AREA TONIGHT...BUT SNOW WITH THIS SYSTEM NOT EXPECTED UNTIL AFTER THE END OF THIS FORECAST VALID PERIOD. && .UPDATE2... HAVE ISSUED A LAKE EFFECT SNOW ADVISORY FOR CASS MI IN SOUTHWEST LOWER MICHIGAN...ALONG WITH ELKHART...MARSHALL...AND STARKE COUNTIES IN NORTHERN INDIANA. LATEST MARINE OBS SUGGESTING ALONG SHORE CONVERGENCE BEGINNING TO SHARPEN AND RADAR MOSAIC OVER PAST HOUR HAS SHOWN BETTER ORGANIZATION OF BANDING ALONG EASTERN SHORELINE EXTENDING INTO NORTHERN BERRIEN COUNTIES. SHORT TERM CONCERN THROUGH 07Z WILL BE FOR LOCALLY HIGHER SNOWFALL RATES ACROSS BERRIEN COUNTY INTO WESTERN CASS MICHIGAN COUNTY...AND THEN FOCUSING MORE OVER SOUTHWEST BERRIEN AND INTO LAPORTE/ST.JOSEPH COUNTIES AFTER 07Z. SNOWFALL RATES OF 1 TO 2 INCHES PER HOUR WILL BE POSSIBLE WITH THIS BAND. STILL CONCERN FOR HEAVIER SNOWFALL TOTALS LATE TONIGHT ACROSS SOUTHWEST BERRIEN AND NORTHERN LAPORTE...WHERE THERMAL CONVERGENCE MAY REMAIN ANCHORED FOR A TIME BEFORE BAND SHIFTS WEST OF THE AREA TOWARD DAYBREAK. .PREV DISCUSSION... /ISSUED 626 PM EST WED JAN 23 2013/ UPDATE1/AVIATION... NR TERM MESOSCALE DVLPMNTS WARRANT AN EARLY UPDATE. IMPRESSIVE SW TROUGH DROPPING SWD OVR NRN WI YIELDING RAPID UPSTREAM LL VEERING ACRS LK MI AND RAPID COOLING OF CLD TOPS SEEN IN IR. COMPOSITE RADAR IMAGERY BLOSSOMING IN KIND AND NO DOUBT AUGMENTED W/SEEDER FEEDER MECHANISM IN PLACE INADV OF MID LVL SW. SHRT TERM RUC ALG W/LATEST 18Z HIGHRES GUIDANCE QUITE OMINOUS LTR THIS EVENING W/DVLPMNT OF INTENSE LK SNOW BANDS. AND UNLIKE LAST SVRL DAYS...MUCH IMPROVED THERMAL ENVIRONMENT W/DEEP...SATURATED ASCENT INDICATED IN WHAT SHLD EVOLVE TWD A LG INTENSE SINGLE BAND AFT MIDNIGHT. AS SUCH WILL JUMP ON EXPANDING ADVSY INTO LAPORTE COUNTY. CONTEMPLATED ADDING ST JOE TOO PER PLACEMENT OF SOME HIGHRES GUIDANCE HWVR THINK DEEPENING NRLY LL FLW COMPONENT WILL PUSH BAND WWD. REGARDLESS A SVRL HOUR BURST OF MOD-HVY SNOW XPCD FOR MUCH OF NW IN/SW MI AS THE EVENING GOES ON. WILL FURTHER MONITOR BAND EVOLUTION THROUGH THIS EVENING FOR POTENTIAL WARNING CRITERIA BEING MET. OTRWS FLIGHT CONDS OBVIOUSLY GOING DOWNHILL AT KSBN OVERNIGHT W/PRIMARILY IFR CONDS PREVAILING. SHRT PD OF MVFR CIGS AT KFWA XPCD THIS EVENING AS SFC TROUGH DROPS SWD BUT MAINLY VFR. PREV DISCUSSION... /ISSUED 337 PM EST WED JAN 23 2013/ SHORT TERM...THROUGH THURSDAY NIGHT. TWOFOLD FOCUS FOR THIS PACKAGE WITH AREA OF LIGHT SNOW FROM N ILLINOIS INTO SW PORTIONS OF THE CWA AND REINVIGORATE LAKE EFFECT POTENTIAL OVER THE NEXT 12 HOURS. RADAR/SFC OBS/SREF PRODUCTS ALL DEPICT AN AREA OF MID/UPPER LEVEL FORCING AND LEADING EDGE OF LFQ OF APPROACHING JET STREAK WITH THE S.W OF INTEREST FOR TONIGHT. THIS IS AIDING IN THE DEVELOPMENT OF A NARROW BAND OF ACCUMULATING SNOW ACROSS PORTIONS OF N/CNTRL IL. A FEW REPORTS OF OVER AN INCH HAVE BEEN NOTED WITH THIS FEATURE AS FAVORABLE DGZ SETUP HAS BEEN UNDERWAY. THIS FEATURE WAS TRACKING SE ACROSS THE SW PARTS OF THE FORECAST AREA WITH RADAR RETURNS INCREASING AND SOME FLURRIES BEING REPORTED. SOMEWHAT OF A WEAKENING TREND HAS BEEN NOTED AS THE AREA BUT STILL EXPECT THE SE TREND TO CONTINUE AND MAY GIVE A FEW TENTHS OF AN INCH OF SNOW AS IT PASSES. PREV UPDATE HAD BUMPED POPS TO LIKELY AND WILL LIKELY RUN WITH PRE 1ST PERIOD TO HANDLE. FOCUS THEN SHIFTS TO LAKE EFFECT FOR THE AREA. INITIAL ENERGY FROM THE SAME WAVE HAS ALLOWED FOR LAKE EFFECT TO EXPAND ACROSS MUCH OF NORTHERN BERRIEN COUNTY OVER THE PAST COUPLE OF HOURS. SOCIAL MEDIA REPORT OF 1 TO 2 INCHES OF NEW SNOW SEEN WITH MUCH LARGER SNOWFLAKES THAN EARLIER EVENT. THESE SNOW SHOWERS SHOULD CONTINUE AND WITH TIME EXPAND AS WAVE PASSES BY AND INCREASES LAKE EFFECT BAND COVERAGE AND INTENSITY AS WELL AS BEGINS TO ALLOW FOR TRANSIENT STATE TONIGHT. ALL HI RES MODELS STILL DEPICT AN INTERESTING SCENARIO TONIGHT WITH BANDS BECOMING MORE FOCUSED ACROSS CNTRL/S LWR MI AND EVENTUALLY DROPPING SOUTH AND WEST AS FLOW BECOMES MORE NW AND EVENTUALLY N OVERNIGHT. EAST AND SOUTH EXTENSION OF THE SNOW SHOWERS REMAINS TOUGH TO DETERMINE WITH SREF BRINGING A BURST OF LIGHT TO MODERATE SNOW TO MUCH OF THE NORTHERN HALF OF THE AREA LATE EVE INTO THE OVERNIGHT HOURS. NAM/RAP/WRF ALL KEEP THE ACTIVITY MORE CONFINED TO WITHIN A FEW COUNTIES INLAND. HAVE TRIED TO CAPTURE TRENDS THE BEST WITHOUT GOING OVERBOARD GIVEN HI BUST POTENTIAL ON EITHER SIDE. SEEING HOW MUCH FORCING HAS BEEN ASSOCIATED WITH THIS WAVE ALREADY AND A SMALL WINDOW OF SEMI FAVORABLE DGZ POSITIONING...COULD SEE SOME AREAS PICKUP A QUICK INCH OR TWO OF SNOW AS THE BAND PASSES. WENT WITH HPC QPF WHICH WAS REASONABLE AND ALIGNED NICELY WITH FAVORED LAKE EFFECT AREAS. GIVEN TRENDS SO FAR AND DISCUSSION WITH EVE SHIFT...WILL HESITANTLY DROP CASS COUNTY FROM THE ADVISORY. WHILE THEY MAY BE AFFECTED BY THE SNOWBAND FOR A PERIOD OF TIME THE OVERALL RISK SEEMS TO BE DIMINISHING WITH MAIN FOCUS FOR THE TIME BEING ON N BERRIEN COUNTY. BY THURSDAY MORNING...BAND WILL LIKELY BE ORIENTED NORTH TO SOUTH AND MOVING WEST AS FLOW BECOMES NE WITH TIME. IN ADDITION...A FEW OF THE HIGH RES MODELS SHOW A MESOLOW SETTING UP QUICKLY ACROSS N LK MI AND DROPPING SOUTH INTO S LK MI TOWARDS 12Z. HAVE ADJUSTED POPS TO REFLECT SLIGHTLY SLOWER TREND IN THE MORNING. CLEARING SKIES SHOULD RAPIDLY TAKE SHAPE IN THE MORNING EAST OF THE BAND. THIS WILL BE SHORT LIVED AS NORTHERN AND SOUTHERN STREAM ENERGY BEGIN TO CONVERGE ON THE AREA. DRY CONDITIONS SHOULD HOLD INTO MUCH OF THURS NGT BEFORE INCREASED FORCING MOVE IN FROM THE NW LATE THURS NGT. GIVEN FOCUS ON FIRST PERIOD OR TWO OF FORECAST AND TREND OF MODELS HAVING A SLOWER ARRIVAL TO ANY PRECIP HAVE KEPT THURS NGT UNTOUCHED WRT POPS AND DEFER TO OVERNIGHT SHIFT TO LOOK AT AGAIN. ANY ACCUMS TOWARDS FRI AM WOULD APPEAR TO BE ON THE LIGHT SIDE. LONG TERM... FRIDAY THROUGH WEDNESDAY...CHALLENGES THIS PACKAGE INCLUDE THE AMOUNT OF SNOW FRIDAY WITH A WEAK UPPER LEVEL SYSTEM AND THE TIMING AND TYPES OF PRECIPITATION NEXT WEEK IN AN UNSETTLED PATTERN. FOR THIS PACKAGE...FAVOR THE ECMWF A LITTLE MORE THAN THE GFS DUE TO RUN TO RUN CONSISTENCY OF THE ECMWF. THE 06Z AND 18Z GFS RUNS HAVE BEEN VERY INCONSISTENT WITH THE 12Z AND 00Z RUN. THE 12Z GFS RUN HAS TRENDED MUCH WARMER TUESDAY FROM THE 06Z RUN AND NOW SUPPORTS THE ECMWF. FOR FRIDAY...THE ONGOING TIMING AND AMOUNTS OF SNOW LOOK GOOD. THE GARCIA METHOD WITH MIXING RATIOS TOPPING 3 G/KG SUPPORT SNOW AMOUNTS OF GENERALLY 1 TO 3 INCHES GIVEN SOMEWHAT LIMITED ISENTROPIC LIFT...BUT FAVORABLE JET DYNAMICS AND AGEOSTROPHIC CIRCULATION. COLDER AIR WILL SPREAD BACK OVER THE REGION WITH MORE LAKE EFFECT SNOW EXPECTED FRIDAY NIGHT INTO SATURDAY. EXTENDED THE TIMING OF THE LAKE EFFECT SNOW A LITTLE MORE INTO SATURDAY GIVEN A FAVORABLE FETCH OVER THE LONG AXIS OF THE LAKE. FOR SUNDAY NIGHT INTO MONDAY...ADDED FREEZING RAIN AND SLEET GIVEN THERMAL PROFILES. UPDATED THE HAZARDOUS WEATHER OUTLOOK IN THIS REGARD FOR THE POTENTIAL FOR THIS WINTRY MIX WITH TRAVEL ISSUES POSSIBLE. TRENDED TUESDAY A LITTLE WARMER GIVEN WARM TEMPERATURES AT 850 MB AND GOOD MIXING EXPECTED. BELIEVE SNOW COVER SHOULD BE VERY LIMITED BY TUESDAY AFTERNOON AND SHOULD NOT BE AN ISSUE IN KEEP TEMPERATURES FROM CLIMBING WELL INTO THE 40S. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ THIS MORNING FOR INZ005-012-014. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST /6 AM CST/ THIS MORNING FOR INZ003-004. MI...LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST THIS MORNING FOR MIZ078. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST THIS MORNING FOR MIZ077. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR LMZ043-046. && $$ SHORT TERM...FISHER LONG TERM...SKIPPER UPDATE1/AVIATION...T UPDATE2...MARSILI AVIATION...MARSILI
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1124 PM CST WED JAN 23 2013 .AVIATION... VFR CONDITIONS TO PREVAIL THROUGH THURSDAY EVENING WITH MAINLY JUST SOME HIGH CLOUDINESS AS SFC HIGH PRESSURE REMAINS IN CONTROL. GUSTY NORTH WINDS TO GRADUALLY DIMINISH BELOW 10 KTS THURSDAY AM THEN VEER TO THE S/SE DURING THE AFTN THROUGH EVE AS THE HIGH PRESSURE SYSTEM BEGINS TO MOVE AWAY FROM REGION. JUST BEYOND THE END OF THE TAF CYCLE... OR LATE THURSDAY NIGHT INTO FRIDAY AM... LIGHT SNOW IS EXPECTED TO DEVELOP OVER THE REGION WITH WARM ADVECTION ALOFT AS STORM SYSTEM PASSES TO OUR NORTH... WHILE ANOTHER PASSES TO THE SOUTH. CONDITIONS LIKELY TO LOWER TO MVFR IN THE LIGHT SNOW WITH IFR POSSIBLE. && .PREV DISCUSSION... /ISSUED 940 PM CST WED JAN 23 2013/ UPDATE... FINAL BAND OF FLURRIES AND SNOW SHOWERS (ROUGHLY 30 MI WIDE) WITH LEADING EDGE FROM NEAR CLINTON TO STERLING WILL CONTINUE TO DIVE SOUTH NEXT FEW HRS EXITING CWA BY 07Z-08Z. THIS MAY BRING QUICK DUSTING OF ACCUM TO FEW LOCATIONS NEAR TO EAST OF MISSISSIPPI RVR. SKIES THEN CLEAR IN WAKE OF SYSTEM OVERNIGHT WITH JUST SOME HIGH THIN CLOUDS. AS FOR WIND CHILL ADVISORY FOR PORTIONS OF NORTHEAST IA AND NORTHWEST IL... IT WENT INTO EFFECT AT 8 PM BUT WE HAVE NOT BEEN CLOSE TO MEETING CRITERIA THUS FAR AS FCST TEMPS HAVE BEEN RUNNING COLDER THAN OBS. TO AVOID ANY CONFUSION I HAVE LEFT ADVISORY IN EFFECT HOWEVER I ADJUSTED WORDING IN ADVISORY TO HIGHLIGHT THE TIME PERIOD LATER TONIGHT THROUGH MID AM THU (08Z- 15Z) AS BEING THE MAIN WINDOW FOR THE DANGEROUSLY COLD WIND CHILLS OF AROUND 20 BELOW ZERO. AS FOR LOWS... TWEAKED UP 1-2 DEGS IN MOST PLACES WITH FCST RUNNING COLDER THAN OBS. LATEST RAP MODEL 2M TEMPS VERIFYING WELL WITH OBS AT 03Z AND SUPPORT LOWS AROUND ZERO TO 5 BELOW NORTH OF I-80 TO SINGLE DIGITS ABOVE ZERO TO THE SOUTH. GRIDS/ZFP HAVE BEEN SENT. PREV DISCUSSION... /ISSUED 656 PM CST WED JAN 23 2013/ UPDATE... BASED ON RADAR/SATL TRENDS AND OBS UPDATED FCST TO INCREASE CLOUD COVER AND MENTION ISOLD SNOW SHOWERS REST OF THE EVE FOR PORTIONS OF NORTHEAST IA AND NORTHWEST IL. PREV DISCUSSION... /ISSUED 258 PM CST WED JAN 23 2013/ SYNOPSIS... A COLD FRONT WAS PUSHING ACROSS EASTERN IA AT MID AFTERNOON WITH NORTHWEST WINDS GUSTING TO 25 TO 30 KNOTS BEHIND THE FRONT. STRONG COLD AIR ADVECTION WAS TAKING PLACE WITH THE PASSAGE OF THE FRONT AS TEMPERATURES HAVE FALLEN INTO THE TEENS IN NORTHERN IA AND SINGLE DIGITS IN SOUTHERN MN. EVEN COLDER FARTHER NORTH WITH READINGS BELOW ZERO ACROSS ND AND NORTHERN AND CENTRAL MN. CURRENTLY IN THE DVN CWA TEMPERATURES RANGED FROM ABOUT 20 FAR NORTH TO LOWER TO MID 30S FAR SOUTH. A NARROW BAND OF DENDRITIC SNOW THIS MORNING ACCUMULATED TO 0.5 TO 2.0 INCHES ROUGHLY ALONG HIGHWAY 20. THIS BAND OF SNOW OCCURRED ON THE CYCLONIC SIDE OF A NARROW 100 KNOT MID LEVEL WIND MAXIMUM WHERE VERTICAL MOTION WAS ENHANCED AND WAS CONCENTRATED IN A TIGHT BAROCLINIC ZONE. 850 MB TEMPERATURES AT 12Z WERE -20C AT KGRB AND +1C AT KOMA. SOUNDINGS INDICATED SATURATION OCCURRED IN THE FAVORED DENDRITIC GROWTH ZONE OF -12 TO -18C. SNOW/LIQUID RATIOS WERE AN INCREDIBLE 120:1 BASED ON OBSERVER MEASUREMENTS. HAASE SHORT TERM...TONIGHT AND THURSDAY... HEADLINES...HAVE ALREADY ISSUED A WIND CHILL ADVISORY FOR PORTIONS OF OUR NORTHERN CWA 8 PM THIS EVENING THROUGH 9 AM THURSDAY FOR WIND CHILLS OF 20 TO 25 BELOW ZERO. TONIGHT...FORECAST FOCUS ON TEMPERATURES AS COLD FRONT BRINGS COLDER WEATHER INTO THE REGION. FREQUENT WIND GUSTS TO 25 TO 30 WITH A FEW GUSTS POSSIBLY TO 35 MPH WILL OCCUR INTO THE EVENING HOURS. THESE WINDS WILL DIMINISH AFTER MIDNIGHT TO ABOUT 10 MPH AS 1044 MB HIGH PRESSURE BUILDS INTO THE REGION OUT OF CANADA. SKIES WILL CONTINUE TO CLEAR OVERNIGHT. OPERATIONAL MODELS HAVE LATCHED ONTO THE COLDER AIRMASS AND GUIDANCE IS NOW COLDER THAN PREVIOUS RUNS. IN ADDITION...THE FRESH SNOW THAT FELL IN OUR FAR NORTH THIS MORNING WILL HELP TO LOWER THE TEMPERATURE EVEN MORE. THEREFORE WILL FORECAST MINIMUM TEMPERATURES AS LOW AS 7 BELOW IN OUR FAR NORTH TO 5 ABOVE SOUTH. THIS WILL GIVE WIND CHILLS OF 15 TO 25 BELOW ZERO ALONG AND NORTH OF INTERSTATE 80. THURSDAY...FRIGID WIND CHILLS WILL CONTINUE THROUGH MID MORNING AND THEN IMPROVING CONDITIONS AS WINDS GO LESS THAN 10 MPH AS THE CENTER OF THE HIGH GETS CLOSER. IN THE AFTERNOON THE HIGH PRESSURE WILL PUSH INTO THE OHIO VALLEY. THIS WILL ALLOW LOW LEVEL WARM AIR ADVECTION TO KICK IN AND MID/HIGH LEVEL CLOUDS SHOULD INCREASE FROM WEST TO EAST. WILL BE A COLD DAY WITH MAXIMUM TEMPERATURES IN THE TEENS NORTH TO LOWER 20S SOUTH. WHERE THE FRESH SNOW FELL ACROSS PORTIONS OF HIGHWAY 20 THIS MORNING THOSE AREAS MAY STRUGGLE TO EVEN REACH THE TEENS ON THURSDAY. HAASE LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY... MODELS ARE CONSISTENT IN BRINGING A SHORT WAVE OUT OF THE NORTHERN PLAINS AND INTO THE WESTERN GREAT LAKES BY 12Z FRIDAY. MODEL QPF PROGS SHOW AN AREA OF LIGHT PRECIPITATION ASSOCIATED WITH THE SHORT WAVE FROM EASTERN IOWA INTO NORTHERN ILLINOIS LATE THURSDAY NIGHT. THE EXCEPTION TO THIS IS THE NAM SOLUTION WHICH KEEPS THE PRECIPITATION CLOSER TO THE S/W OVER MN AND WI. IT APPEARS THE NAMS LACK OF PCPN AWAY FROM THE S/W MAY BE DUE TO THE NAM HOLDING ON TO A LAYER OF NEAR SURFACE DRY AIR LONGER THAN THE OTHER OPERATIONAL MODELS. SINCE FORCING ON THE NAM LOOKS SIMILAR TO THE OTHER MODELS WILL STEER AWAY FROM IT/S DRIER SOLUTION AND LEAN TOWARD THE CONSENSUS. LIGHT SNOW IS EXPECTED TO SPREAD OVER THE AREA BEGINNING LATE THURSDAY EVENING AND CONTINUE OVERNIGHT. TIME HEIGHT PLOTS WERE SHOWING A BRIEF PERIOD...1 TO 2 HOURS...OF OPTIMAL LIFT IN THE DENDRITIC ZONE AFTER MIDNIGHT WHICH SHOULD PRODUCE MOST OF THE ACCUMULATIONS. WITH WATER EQUIVALENT AMOUNTS EXPECTED TO BE AROUND A TENTH OF AN INCH...ESPECIALLY OVER NORTHWEST ILLINOIS AND SNOW RATIOS IN THE 15 TO 20:1 RANGE...WE SHOULD SEE ACCUMULATIONS IN THE 1 TO 2 INCH RANGE ALONG AND EAST OF THE MISSISSIPPI RIVER BY 6 AM FRIDAY. THE SNOW SHOULD END QUICKLY FROM WEST TO EAST FRIDAY MORNING WITH ONLY SOME LINGERING FLURRIES POSSIBLE IN THE FAR EAST DURING THE AFTERNOON. AFTER MORNING LOWS IN THE TEENS FRIDAY...AFTERNOON SUN AND SOME MIXING SHOULD HELP TEMPERATURES REBOUND INTO THE 20S. HIGH PRESSURE MOVING INTO CENTRAL IOWA BY SATURDAY MORNING AND CLEAR SKIES SHOULD ALLOW GOOD RADIATIONAL COOLING. KEPT MINS IN THE SINGLE DIGITS OVER THE NORTHWEST HALF OF THE AREA SATURDAY MORNING AND AROUND 10 IN THE SOUTHEAST. THESE TEMPERATURES MAYBE ON THE WARM SIDE IF THE SNOWFALL PANS OUT THURSDAY NIGHT. SATURDAY WILL BE A TRANSITION DAY WITH THE WESTERN U.S. UPPER RIDGE MOVING EAST INTO THE CENTRAL U.S. AND A TROF DEVELOPING OVER THE WEST BY SATURDAY EVENING. LATE SATURDAY NIGHT A S/W EJECTS OUT OF THE WESTERN TROF AND MOVES THROUGH THE MID MISSISSIPPI VALLEY SUNDAY. THE MEDIUM RANGE MODELS ALL SHOW THIS SCENARIO BUT THERE ARE TIMING DIFFERENCES WITH THE ECMWF THE SLOWEST AND THE GFS ONE OF THE FASTER SOLUTIONS. DESPITE THE TIMING ISSUES...THE MODELS ALL SUGGEST A MIXED PRECIP EVENT SUNDAY AND SUNDAY NIGHT. THE PRECIP COULD BEGIN IN THE SOUTHWEST EARLY SUNDAY MORNING AND SPREAD NORTHEAST DURING THE DAY WITH THE PRECIP TYPE INCLUDING SNOW...FREEZING RAIN...SLEET AND RAIN. FOR MONDAY AND TUESDAY UNSETTLED WEATHER WILL STAY OVER THE AREA AS THE UPPER FLOW BECOMES SOUTHWESTERLY EARLY IN THE PERIOD CAUSING A WARM FRONT TO LIFT NORTH AND THEN STALL OVER OR JUST SOUTH OF THE FORECAST AREA. A WAVE IS THEN EXPECTED TO LIFT NORTHEAST ALONG THE BOUNDARY TUESDAY. THIS PATTERN SHOULD KEEP A MIX OF PRECIPITATION OVER THE AREA WITH MAINLY RAIN FAVORED IN THE SOUTH AND A MIX OF RAIN AND SNOW OVER THE NORTH MONDAY AND MONDAY NIGHT WITH MAINLY RAIN OVER THE ENTIRE AREA TUESDAY. THUNDERSTORMS OVER THE SOUTH AREN/T OUT OF THE QUESTION TUESDAY AS THE SURFACE LOW MOVES THROUGH OR NEAR THE FORECAST AREA. THE STALLED BOUNDARY WILL ALSO BRING MILD TEMPERATURES TO THE REGION WITH 30S AND 40S EXPECTED MONDAY AND 40S AND LOW 50S ON TUESDAY. COLDER AIR IS EXPECTED TO PUSH BACK INTO THE REGION TUESDAY NIGHT AND WEDNESDAY BEHIND THE DEPARTING SURFACE WAVE. DLF && .DVN WATCHES/WARNINGS/ADVISORIES... IA...WIND CHILL ADVISORY UNTIL 9 AM CST THURSDAY FOR BENTON-BUCHANAN- DELAWARE-DUBUQUE-JACKSON-JONES-LINN. IL...WIND CHILL ADVISORY UNTIL 9 AM CST THURSDAY FOR JO DAVIESS. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
400 AM CST THU JAN 24 2013 ...UPDATED FOR SHORT TERM DISCUSSION... .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 347 AM CST THU JAN 24 2013 A SHORTWAVE TROUGH WAS MOVING SOUTHEAST INTO THE GREAT LAKES REGION THIS MORNING AND COLD HIGH PRESSURE WAS PUSHING SOUTH IN ITS WAKE. THE WESTERN EDGE OF THIS COLD AIR WAS MOVING INTO SOUTHWEST KANSAS IN UPSLOPE FASHION FROM THE NORTHEAST. MEANWHILE, THE NEXT SHORTWAVE TROUGH WAS PROGRESSING ACROSS THE PACIFIC NORTHWEST EARLY THIS MORNING. THIS SYSTEM WILL APPROACH THE NORTHERN HIGH PLAINS BY THIS AFTERNOON AND RESULT IN SURFACE TROUGHING IN THE LEE OF THE NORTHERN ROCKIES. IF THIS SYSTEM WAS FASTER, THE ASSOCIATED PACIFIC COLD FRONT WOULD HAVE NO PROBLEM SCOURING THE SHALLOW COLD AIR OUT OF WESTERN KANSAS. HOWEVER, IT APPEARS THAT THE COLD FRONTAL PASSAGE WILL HOLD OFF UNTIL LATER TONIGHT. ALSO, THE LEE TROUGH AND ASSOCIATED SOUTHERLY WINDS AHEAD OF THE SYSTEM ARE NOT ADVERTISED TO BE STRONG ENOUGH TO SCOUR OUT THE COLD AIR. INSTEAD, THE ISENTROPIC LIFT WITH THE DEVELOPING SOUTHERLIES WILL AID IN LOW CLOUD DEVELOPMENT THIS MORNING AND A WEAK UPSLOPE COMPONENT WILL PERSIST AT LOWER LEVELS THROUGH THE DAY. THE NAM SOUNDINGS SHOW A SHALLOW LAYER OF SATURATION ABOVE 900MB AND THIS IS REASONABLE BASED ON THE HIGHER OBSERVED SURFACE DEWPOINTS CURRENTLY RESIDING ACROSS OKLAHOMA. ALSO, PLENTY OF HIGH LEVEL CLOUD WAS PRESENT ACROSS KANSAS THIS MORNING AND SHOULD PERSIST THROUGH THE DAY AND FURTHER LIMIT INSOLATION. THEREFORE, TEMPERATURES FROM DODGE CITY EASTWARD WILL STAY AT OR BELOW FREEZING. SOME COLD AIR EROSION IS EXPECTED IN FAR WESTERN KANSAS WHERE TEMPERATURES COULD REACH INTO THE UPPER 30S AND 40S. THE OFFICIAL FORECAST WILL BE A FEW DEGREES COLDER THAN THE NAM. FOR SOME REASON THE RAP ERODES THE COLD AIR WITH HIGHS IN THE MID 40S EVEN AS FAR EAST AS DODGE CITY. BY TONIGHT, THE LOW LEVEL WINDS ARE EXPECTED TO VEER TO THE SOUTHWEST AS THE AFOREMENTIONED PACIFIC COLD FRONT APPROACHES. THUS THE LOW CLOUDS WILL RAPIDLY CLEAR OUT. TEMPERATURES WILL INITIALLY FALL INTO THE 20S OVERNIGHT BUT THEN HOLD STEADY OR EVEN RISE AFTER 3 AM AS VERTICAL MIXING INCREASES BEHIND THE PACIFIC COLD FRONT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 330 AM CST THU JAN 24 2013 FRIDAY WILL START WITH THE UPPER LEVEL FLOW OVER KANSAS IN A SLIGHT DOWNSLOPE PATTERN WITH NORTHWEST FLOW ALOFT. SKIES SHOULD START OUT FRIDAY MORNING SUNNY, WITH LIGHT NORTH TO NORTHWEST SURFACE WINDS. BY FRIDAY AFTERNOON, A FEW HIGH CIRRUS CLOUDS WILL STREAM IN WITH SKIES BECOMING MOSTLY SUNNY, AND WINDS SHIFTING TO THE SOUTH AT 10 MPH OR LESS. CLOUDS WILL CONTINUE TO INCREASE FRIDAY NIGHT. WINDS WILL REMAIN SOUTH AT AROUND 10 MPH, SO MINIMUM TEMPS WILL BE MILD IN THE MID 20S TO LOWER 30S. ON SATURDAY, AN UPPER LEVEL WAVE WILL BE APPROACHING FROM THE SOUTHWEST. PLENTY OF MOISTURE IS STILL SITTING OVER TEXAS AND WILL STILL BE THERE SATURDAY. THE DEEP, SOUTHWEST FLOW ALOFT WILL ADVECT SOME OF THAT MOISTURE NORTH INTO KANSAS. WHEN THAT UPPER WAVE APPROACHES LATE SATURDAY, THE MOISTURE WILL BE IN PLACE. THERE ARE SLIGHT CHANCES FOR RAIN IN OUR EAST VERY LATE ON SATURDAY, BUT PRECIPITATION CHANCES WILL INCREASE SATURDAY NIGHT AS THE UPPER LIFT MOVES IN. PRECIPITATION CHANCES WILL BE AS HIGH AS 50 PERCENT IN OUR EAST AND SOUTHEAST, BASICALLY EAST OF HIGHWAY 19. AS FOR PRECIPITATION, RAIN WILL DOMINATE, AND RAINFALL AMOUNTS WILL BE ON THE LIGHT SIDE. THE GFS MODEL HAS THE MOST PRECIP, WITH 0.25 IN OUR EAST, BUT THE GEM AND THE ECMWF MODELS BOTH PRODUCE LESS THAN A TENTH OF AN INCH OF RAINFALL SATURDAY AND SUNDAY MORNING. SUNDAY, PRECIP CHANCES WILL JUST BE ACROSS OUR EXTREME EASTERN TIER OF COUNTIES, FROM ELLIS SOUTH TO BARBER COUNTY. AFTER THIS WAVE PASSES SUNDAY, THE UPPER PATTERN WILL TURN TO THE SOUTHWEST, WITH A WARMING TREND. BY TUESDAY, MAX TEMPS SHOULD BE WELL INTO THE MID 50S NORTH OF I-70 TO THE MID 60S SOUTH ALONG THE OKLAHOMA BORDER. A LARGE, BROAD SCALE UPPER TROUGH WILL BE MOVING INTO THE PLAINS TUESDAY INTO WEDNESDAY, AND A LOW END SLIGHT CHANCE FOR RAIN WILL EXIST OVER OUR NORTHERN MOST COUNTIES OF ELLIS AND TREGO. I AM NOT TOO CONFIDENT IN THESE PRECIPITATION CHANCES TUESDAY AND WEDNESDAY, SO STAYED WITH LOW 15-16 PERCENT CHANCES ONLY, FOR NOW. FOR MOST OF THIS EXTENDED FORECAST, THE ECMWF MODEL WAS FAVORED. THE GFS SEEMS TOO WET AND SLOWER WITH THE UPPER PROGRESSION OF WAVES. THE GEM CANADIAN MODEL ON THE OTHER HAND IS FASTER AND LESS WET. THUS, THE ECMWF IS A GOOD COMPROMISE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1102 PM CST WED JAN 23 2013 LOW LEVEL EASTERLY UPSLOPE FLOW WILL RESULT IN A GRADUAL MOISTENING OF THE LOWER LEVELS, LEADING TO MVFR CIG DEVELOPMENT BETWEEN 11 AND 14Z AT GCK/DDC/HYS. WINDS WILL SHIFT TO A SOUTHERLY DIRECTION LATER IN THE AFTERNOON, RESULTING IN A LOSS OF UPSLOPE AND EROSION OF THE CIGS. && .PRELIMINARY POINT TEMPS/POPS... DDC 32 25 52 27 / 0 0 0 0 GCK 37 25 52 28 / 0 0 0 0 EHA 47 27 53 32 / 0 0 0 0 LBL 38 26 53 29 / 0 0 0 0 HYS 32 22 50 26 / 0 0 0 0 P28 29 27 53 26 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...FINCH LONG TERM...BURKE AVIATION...FINCH
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
425 AM EST THU JAN 24 2013 .SYNOPSIS... A CLIPPER SYSTEM MOVES ACROSS THE MID ATLANTIC REGION THIS MORNING. HIGH PRESSURE BUILDS IN FROM THE NORTH THURSDAY AND SETTLES OVER THE AREA THURSDAY NIGHT. ANOTHER LOW PRESSURE SYSTEM CROSSES THE REGION FRIDAY AFTERNOON INTO FRIDAY EVENING...BEFORE HIGH PRESSURE RETURNS FOR THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A CLIPPER SYSTEM IS PRESENTLY AFFECTING THE AREA WITH SNOW FALLING FROM THE CENTRAL VA PIEDMONT TO THE EASTERN SHORE. THE HEAVIEST BAND PER 88D RADAR MOSAIC AS DEVELOPED ROUGHLY ALONG A LINE FROM EZF-NUI-WAL WITH ADDITIONAL ENHANCEMENT OF ECHOES OVER THE MIDDLE PENINSULA. 24/06Z RUC DATA INDICATES ROBUST FRONTOGENETIC FORCING PERSISTING FROM THE NRN NECK/MIDDLE PENINSULA TO THE EASTERN SHORE OVER THE NEXT FEW HOURS BEFORE DECLINING WNW-ESE FROM ABOUT 12-14Z. GIVEN THIS THERE IS RATHER HIGH CONFIDENCE OF 1-2IN OF SNOW ACCUMULATION WITH ISOLATED AMOUNTS TO 3IN POSSIBLE IN THE HEAVIEST BAND. RUC DATA ALSO SUGGEST THE BEST WAA BEGINS TO DIMINISH OVER THE PIEDMONT DURING THE NEXT FEW HOURS...BUT GIVEN THE PERSISTENCE OF LIGHT SNOW OVER THE PAST FEW HOURS SOME LOCATIONS COULD RECEIVE A TOTAL SNOW ACCUMULATION OF 1 TO PERHAPS 2IN. A WINTER WEATHER ADVISORY HAS BEEN ISSUED TO ACCOUNT FOR THIS. THE ENTIRE ADVISORY IS IN ONE SEGMENT ENDING AT 15Z (10AM) FOR SIMPLICITY...BUT WESTERN AREAS WILL LIKELY SEE AN IMPROVEMENT WELL BEFORE THEN. A PORTION OF THE MAIN POLAR VORTEX DROPS SE ACROSS NY OVERNIGHT TOWARD LONG ISLAND BY MIDDAY. THIS TRIGGERS THE CLIPPER TO STRENGTHEN OFFSHORE DRIVING STRONG CAA ACROSS THE MID ATLANTIC THIS MORNING. FORECAST SOUNDINGS INDICATE STEEP LOW-LEVEL LAPSE RATES WITH LINGERING MOISTURE FROM ABOUT 950-750MB RESULTING IN SOME LIMITED CONVECTIVE INSTABILITY. HENCE THERE IS A POTENTIAL FOR SCATTERED OR PERHAPS A BROKEN LINE OF SNOW SHOWERS TRACKING N-S THROUGH THE MORNING FROM EASTERN VA TO NE NC AS SUGGESTED BY HIGH-RES MODEL DATA. A RATHER QUICK CLEARING TREND IS EXPECTED FROM NW-SE BY AFTERNOON ALTHOUGH CHILLY TEMPERATURES WILL CONTINUE. HIGHS SHOULD RANGE FROM THE UPPER 20S/LOW 30S N...TO MID 30S S. A 15-20MPH N WIND WITH GUSTS TO 25 MPH WILL PRODUCE WIND CHILL VALUES OF 15-20 THROUGH MUCH OF THE DAY. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... A 1035MB ARCTIC (IN ORIGIN) HIGH BUILDS INTO THE MID ATLANTIC TONIGHT. MEANWHILE...ANOTHER CLIPPER DIVES SE ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST. HIGH THIN CIRRUS WILL LIKELY BEGIN TO OVERSPREAD THE REGION LATE...BUT MOST OF THE NIGHT SHOULD REMAIN CLEAR TO MOSTLY CLEAR. THIS WILL ALLOW TEMPERATURES TO DROP OFF VERY QUICKLY EVENTUALLY PLUMMETING TO 10-15 ASIDE FROM 15-20 FOR EXTREME SE COASTAL LOCATIONS. AREAS WITH SNOW COVER FROM THE CURRENT CLIPPER COULD FALL TO 5-10...ESPECIALLY OVER THE EASTERN SHORE WHERE THE SKY SHOULD REMAIN CLEAR FOR THE LONGEST DURATION. HIGH PRESSURE REMAINS OVER THE REGION TO BEGIN THE DAY FRIDAY BEFORE SHIFTING OFFSHORE DURING THE AFTERNOON AS THE NEXT CLIPPER APPROACHES FROM THE WEST. THE INITIAL SHORTWAVE REMAINS WELL N OF THE REGION...BUT SECONDARY SHORTWAVE ENERGY TRIGGERS A WEAK LOW ALONG THE ARCTIC BOUNDARY...WHICH TRACKS ACROSS NC BEFORE MOVING OFF THE COAST AND DEEPENING WELL OFFSHORE FRIDAY NIGHT. MOISTURE INCREASES ALOFT THROUGHOUT THE MORNING. HOWEVER...THE LOWER LEVELS WILL REMAIN VERY DRY AND FORECAST SOUNDING DO NOT INDICATE SATURATION UNTIL 18-21Z FOR THE PIEDMONT...AND 21-00Z FOR I-95 EAST. DRY AIR ALOFT THEN QUICKLY INTRUDES THROUGH THE EVENING AS THE LOW DEEPENS OFFSHORE. GIVEN THIS...QPF AMOUNTS WILL BE LIGHT AND EVEN 0.25IN SEEMS DIFFICULT TO ACHIEVE. THE BEST FRONTOGENETIC FORCING APPEARS TO SET-UP FROM S-CENTRAL/SE VA TO THE EASTERN SHORE DURING A SHORT PERIOD FORM LATE FRIDAY AFTERNOON INTO FRIDAY EVENING. P-TYPE SHOULD PRIMARILY BE SNOW. HOWEVER...WITH SSW FLOW A MIX OR CHANGE TO IP IS LIKELY OVER EXTREME SE VA AND NE NC. PORTIONS OF NE NC COULD EVEN HAVE THE PRECIP END AS A PERIOD OF LIGHT FREEZING DRIZZLE. ANY ICE ACCUMULATION SHOULD BE MINIMAL. AS FOR SNOW ACCUMULATION...A BAND OF 1-2IN IS EXPECTED FROM INTERIOR NE NC ACROSS S-CENTRAL/SE VA...WHILE 2-3IN IS POSSIBLE OVER THE EASTERN SHORE. ELSEWHERE...SNOW ACCUMULATION SHOULD BE AN INCH OR LESS. HIGHS FRIDAY SHOULD RANGE FROM THE UPPER 20 NW...TO THE MID/UPPER 30S SE (PRIOR TO PRECIP EVAPORATING INTO THE AMBIENT AIRMASS). DRY NW FLOW PREVAILS SATURDAY AS THE LOW STRENGTHENS WELL OFF THE COAST AND SFC HIGH PRESSURE RETURNS. LOWS SHOULD RANGE FROM THE UPPER TEENS NW...TO MID 20S SE...FOLLOWED BY HIGHS RANGING FROM THE LOW/MID 30S N...TO AROUND 40 S. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... GOING WITH A COMBINATION OF THE 12Z GFS AND 12Z ECMWF MODELS FOR THE EXTENDED PERIOD. DRY AND COLD CONDITIONS EXPECTED INITIALLY SAT NGT AND SUN...THEN MILDER...ABOVE NORMAL TEMPS FCST FOR TUE AND WED. HI PRES WILL BLD INTO AND OVR THE AREA SAT NGT AND SUN...THEN SLIDE OFF THE CST FOR MON INTO WED. THERE COULD BE ISLTD RAIN SHOWERS...ESPLY ACRS EXTRM NW OR NRN CNTIES MON AFTN THRU TUE NEAR A WARM FRONT. OTHRWISE...A BETTER CHC FOR RAIN SHOWERS WILL BE DURING WED...AS A COLD FRONT PUSHES INTO THE REGION. MIN TEMPS WILL RANGE FM THE UPR TEENS TO MID 20S SUN MORNG...IN THE MID 20S TO NEAR 30 MON MORNG...IN THE MID 30S TO LWR 40S TUE MORNG...AND IN THE 40S WED MORNG. MAX TEMPS WILL RANGE FM THE MID 30S TO LWR 40S SUN...IN THE 40S TO NEAR 50 MON...IN THE LWR 50S TO LWR 60S TUE...AND MAINLY IN THE UPR 50S TO MID 60S WED. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... SNOW SHOWERS ARE EXPECTED OVRNGT THRU EARLY THU MORNG...ESPECIALLY AT RIC/SBY FM A CLIPPER SYSTEM MOVING THRU THE AREA. VSBY/CIG REDUCTIONS (TO MVFR AT RIC AND IFR AT SBY) HAVE BEEN ADDED...WITH MENTION OF -SN IN THE SBY/RIC TAFS UNTIL 12Z. VFR CONDITIONS WILL PREVAIL AFTER 12Z THU AS WINDS SHIFT TO THE N BEHIND THIS SYSTEM. WINDS WILL BE GUSTY THRU MUCH OF THE AFTN DUE TO A TIGHTENING PRESSURE GRADIENT AS THE SYSTEM STRENGTHENS OFFSHORE. ANOTHER LO PRES SYSTEM MAY BRING A PERIOD OF SNOW (MIXED PCPN FOR ECG) TO THE AREA FRI AFTN/EVENG WITH BRIEF PERIODS OF IFR POSSIBLE. DRY WX AND VFR CONDITIONS EXPECTED FOR SAT AND SUN. && .MARINE... ALL MARINE HEADLINES ARE NOW IN EFFECT WITH CONDITIONS EXPECTED WITHIN 12 HR. AREA OF LO PRES CURRENTLY OVER THE AREA WILL PUSH OFFSHORE THRU THE MRNG HRS...ALLOWING FOR WINDS TO BECOME N/NW OVER ALL WATERS BY MID MRNG. STRONG SFC PRES RISES WEST OF THE AREA AND CAA WILL LEAD TO GALE CONDITIONS OVER THE SOUND/MOUTH OF THE BAY/COASTAL WATERS SOUTH OF PARRAMORE ISLAND...WITH STRONG SCA CONDITIONS OVER ALL OTHER WATERS. GALE FORCE WINDS WILL LAST UNTIL ERLY THIS EVENG WHEN CAA CEASES...WITH GALE HEADLINES LIKELY BEING REPLACED BY A SCA. EXPECT 5-7 FT SEAS OVER COASTAL WATERS AND 3-5 FT WAVES OVER THE BAY TDY. STRONG HI PRES BLDS DIRECTLY OVER THE AREA LATE TNGT INTO FRI AS MARINE CONDITIONS IMPROVE. WINDS BECOME SOUTHERLY ~10 KT FRI AFTN AS THE HI MOVES OFFSHORE. AN AREA OF LO PRES WILL TRACK INTO THE AREA LATE FRI...STRENGTHENING AS IT PUSHES OFFSHORE FRI NGT INTO SAT. SCA CONDITIONS ARE EXPECTED BEHIND THIS SYSTM WITH GUSTS UP TO GALE FORCE POSSIBLE...ESPECIALLY OVER COASTAL WATERS. && .HYDROLOGY... FLOOD WARNINGS REMAIN IN EFFECT FOR THE BLACKWATER RIVER ABOVE FRANKLIN AND THE NOTTOWAY RIVER AT SEBRELL. BOTH RIVERS CONTINUE TO TREND DOWNWARD. SEE LATEST FLSAKQ/FLWAKQ FOR DETAILS. && .CLIMATE... AT RICHMOND...TODAY`S HIGH WAS ABOVE 32 F...NOW MAKING IT 732 CONSECUTIVE DAYS WITH A HIGH ABOVE 32 F (AND STILL COUNTING). THE PREVIOUS LONGEST STREAK HAD BEEN 730 DAYS (12/27/1948 TO 12/26/1950). IT WILL BE CLOSE THURSDAY AS THE LATEST FORECAST IS FOR HIGHS NEAR 32 F. NOTE: NORFOLK HAS SET NO RECORDS WITH REGARD TO THESE CRITERIA. WELL BELOW AVERAGE TEMPERATURES CONTINUE THURS BUT STILL NOT GOING TO CHALLENGE ANY RECORDS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR MDZ021>025. NC...NONE. VA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ049-063-064-072>078-083>086-099-100. MARINE...GALE WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ633-634-654- 656-658. SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR ANZ630>632-650- 652. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ635>638. && $$ SYNOPSIS...AJZ NEAR TERM...AJZ SHORT TERM...AJZ LONG TERM...TMG AVIATION...MAS MARINE...MAS HYDROLOGY...AKQ CLIMATE...AKQ
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
249 AM EST THU JAN 24 2013 .SYNOPSIS... A CLIPPER SYSTEM MOVES ACROSS THE MID ATLANTIC REGION LATE TONIGHT INTO THURSDAY MORNING. HIGH PRESSURE BUILDS IN FROM THE NORTH THURSDAY AND SETTLES OVER THE AREA THURSDAY NIGHT. ANOTHER LOW PRESSURE SYSTEM CROSSES THE REGION FRIDAY AFTERNOON INTO FRIDAY EVENING...BEFORE HIGH PRESSURE RETURNS FOR THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A CLIPPER SYSTEM IS PRESENTLY AFFECTING THE AREA WITH SNOW FALLING FROM THE CENTRAL VA PIEDMONT TO THE EASTERN SHORE. THE HEAVIEST BAND PER 88D RADAR MOSAIC AS DEVELOPED ROUGHLY ALONG A LINE FROM EZF-NUI-WAL WITH ADDITIONAL ENHANCEMENT OF ECHOES OVER THE MIDDLE PENINSULA. 24/06Z RUC DATA INDICATES ROBUST FRONTOGENETIC FORCING PERSISTING FROM THE NRN NECK/MIDDLE PENINSULA TO THE EASTERN SHORE OVER THE NEXT FEW HOURS BEFORE DECLINING WNW-ESE FROM ABOUT 12-14Z. GIVEN THIS THERE IS RATHER HIGH CONFIDENCE OF 1-2IN OF SNOW ACCUMULATION WITH ISOLATED AMOUNTS TO 3IN POSSIBLE IN THE HEAVIEST BAND. RUC DATA ALSO SUGGEST THE BEST WAA BEGINS TO DIMINISH OVER THE PIEDMONT DURING THE NEXT FEW HOURS...BUT GIVEN THE PERSISTENCE OF LIGHT SNOW OVER THE PAST FEW HOURS SOME LOCATIONS COULD RECEIVE A TOTAL SNOW ACCUMULATION OF 1 TO PERHAPS 2IN. A WINTER WEATHER ADVISORY HAS BEEN ISSUED TO ACCOUNT FOR THIS. THE ENTIRE ADVISORY IS IN ONE SEGMENT ENDING AT 15Z (10AM) FOR SIMPLICITY...BUT WESTERN AREAS WILL LIKELY SEE AN IMPROVEMENT WELL BEFORE THEN. A PORTION OF THE MAIN POLAR VORTEX DROPS SE ACROSS NY OVERNIGHT TOWARD LONG ISLAND BY MIDDAY. THIS TRIGGERS THE CLIPPER TO STRENGTHEN OFFSHORE DRIVING STRONG CAA ACROSS THE MID ATLANTIC THIS MORNING. FORECAST SOUNDINGS INDICATE STEEP LOW-LEVEL LAPSE RATES WITH LINGERING MOISTURE FROM ABOUT 950-750MB RESULTING IN SOME LIMITED CONVECTIVE INSTABILITY. HENCE THERE IS A POTENTIAL FOR SCATTERED OR PERHAPS A BROKEN LINE OF SNOW SHOWERS TRACKING N-S THROUGH THE MORNING FROM EASTERN VA TO NE NC AS SUGGESTED BY HIGH-RES MODEL DATA. A RATHER QUICK CLEARING TREND IS EXPECTED FROM NW-SE BY AFTERNOON ALTHOUGH CHILLY TEMPERATURES WILL CONTINUE. HIGHS SHOULD RANGE FROM THE UPPER 20S/LOW 30S N...TO MID 30S S. A 15-20MPH N WIND WITH GUSTS TO 25 MPH WILL PRODUCE WIND CHILL VALUES OF 15-20 THROUGH MUCH OF THE DAY. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... CAA RESUMES THURSDAY AS HIGH PRESSURE BUILDS IN FROM THE N RE- ENFORCING THE ARCTIC AIR. HIGH TEMPERATURES SHOULD RANGE FROM THE UPPER 20S N...TO MID 30S S UNDER A PARTLY TO MOSTLY SUNNY SKY. A N WIND OF 15-20 MPH...WITH GUSTS TO 25-30 MPH WILL PUSH WIND CHILL VALUES INTO THE UPPER SINGLE DIGITS TO MID TEENS THURSDAY MORNING...WHICH WILL ONLY IMPROVE TO THE MID TEENS TO LOW 20S BY AFTERNOON. A 1030-1035M AREA OF HIGH PRESSURE BUILDS INTO THE REGION THURSDAY NIGHT THROUGH FRIDAY MORNING. CLEAR SKIES EARLY ON SHOULD ALLOW LOW TEMPERATURES TO FALL INTO THE TEENS AND POTENTIALLY SINGLE DIGITS OVER THE EASTERN SHORE. HIGH PRESSURE WEAKENS AND SHIFTS OFFSHORE FRIDAY AFTERNOON AHEAD OF A DISORGANIZED AREA OF LOW PRESSURE APPROACHING FROM THE WEST...WHICH WEAKENS FRIDAY AFTERNOON AND THEN REDEVELOPS OFF THE COAST FRIDAY NIGHT. THIS REMAINS A LOW CONFIDENCE FORECAST AT THIS TIME...BUT PRESENTLY THERE IS LITTLE MODEL DATA THAT SUPPORTS THIS BEING A SUBSTANTIAL WINTER STORM. ALL AREAS SHOULD BE COLD ENOUGH FOR SNOW...WITH THE POSSIBLE EXCEPTION OF THE FAR SE (NE NC) WHERE SOME RAIN MAY MIX IN. OUTSIDE OF MAYBE COASTAL NE NC...P-TYPE SHOULD BE ALL SNOW WITH MOST DATA INDICATING ONLY A MINOR ACCUMULATION (COATING TO 2 INCHES) AT THIS TIME. SIMILAR TO TONIGHT...A DRY AIRMASS WILL BE IN PLACE SO INITIAL PRECIPITATION WILL EVAPORATE TO MOISTEN THE AIRMASS. IF MODELS CONTINUE ON CURRENT TRENDS...THEN THE BEST CHANCE FOR 1-2" OF SNOW WILL BE ACROSS SE VA AND NE NC (SOUTHEAST OF METRO RIC). DRY NW FLOW PREVAILS LATE FRIDAY NIGHT INTO SATURDAY AS THE LOW STRENGTHENS WELL OFF THE COAST AND SFC HIGH PRESSURE RETURNS. LOWS SHOULD RANGE FROM THE UPPER TEENS NW...TO UPPER 20S SE. HIGHS SATURDAY IN THE 30S. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... GOING WITH A COMBINATION OF THE 12Z GFS AND 12Z ECMWF MODELS FOR THE EXTENDED PERIOD. DRY AND COLD CONDITIONS EXPECTED INITIALLY SAT NGT AND SUN...THEN MILDER...ABOVE NORMAL TEMPS FCST FOR TUE AND WED. HI PRES WILL BLD INTO AND OVR THE AREA SAT NGT AND SUN...THEN SLIDE OFF THE CST FOR MON INTO WED. THERE COULD BE ISLTD RAIN SHOWERS...ESPLY ACRS EXTRM NW OR NRN CNTIES MON AFTN THRU TUE NEAR A WARM FRONT. OTHRWISE...A BETTER CHC FOR RAIN SHOWERS WILL BE DURING WED...AS A COLD FRONT PUSHES INTO THE REGION. MIN TEMPS WILL RANGE FM THE UPR TEENS TO MID 20S SUN MORNG...IN THE MID 20S TO NEAR 30 MON MORNG...IN THE MID 30S TO LWR 40S TUE MORNG...AND IN THE 40S WED MORNG. MAX TEMPS WILL RANGE FM THE MID 30S TO LWR 40S SUN...IN THE 40S TO NEAR 50 MON...IN THE LWR 50S TO LWR 60S TUE...AND MAINLY IN THE UPR 50S TO MID 60S WED. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... SNOW SHOWERS ARE EXPECTED OVRNGT THRU EARLY THU MORNG...ESPECIALLY AT RIC/SBY FM A CLIPPER SYSTEM MOVING THRU THE AREA. VSBY/CIG REDUCTIONS (TO MVFR AT RIC AND IFR AT SBY) HAVE BEEN ADDED...WITH MENTION OF -SN IN THE SBY/RIC TAFS UNTIL 12Z. VFR CONDITIONS WILL PREVAIL AFTER 12Z THU AS WINDS SHIFT TO THE N BEHIND THIS SYSTEM. WINDS WILL BE GUSTY THRU MUCH OF THE AFTN DUE TO A TIGHTENING PRESSURE GRADIENT AS THE SYSTEM STRENGTHENS OFFSHORE. ANOTHER LO PRES SYSTEM MAY BRING A PERIOD OF SNOW (MIXED PCPN FOR ECG) TO THE AREA FRI AFTN/EVENG WITH BRIEF PERIODS OF IFR POSSIBLE. DRY WX AND VFR CONDITIONS EXPECTED FOR SAT AND SUN. && .MARINE... CALM CONDITIONS THIS EVENING AND OVERNIGHT WILL GIVE WAY TO ROUGH CONDITIONS BY EARLY THURSDAY MORNING. A CLIPPER SYSTEM WILL SWING ACROSS THE WATERS FROM NW TO SE BEFORE MOVING OFF THE MID ATLANTIC COAST THURSDAY MORNING. WINDS WILL SHIFT TO A W OR NW DIRECTION IN THE VICINITY OF THE COLD FRONT...THEN BECOME NW-N BEHIND IT AS THE PRESSURE GRADIENT TIGHTENS AND STRONG CAA COMMENCES. GENERALLY WINDS WILL BE 15-20 KT ALL WATERS DURING THE PRE-DAWN HOURS...WHICH WILL THEN INCREASE RAPIDLY BY MID MORNING. CLOSEST TO THE DEPARTING LOW PRESSURE SYSTEM...GALE FORCE WIND GUSTS OF 35-40 KT WILL OCCUR FROM MID MORNING THROUGH THE AFTERNOON OVER THE FOLLOWING AREAS: COASTAL WATERS FROM PARRAMORE ISLAND TO CURRITUCK LIGHT...CURRITUCK SOUND...AND THE MOUTH OF CHES BAY. GALE CONDITIONS ARE EXPECTED TO DIMINISH INTO SOLID SCA SPEEDS BY EARLY THU EVENING. GALE WARNINGS HAVE BEEN ISSUED FOR THESE AREAS...WITH THE MAIN IMPACT OCCURRING THURSDAY MID MORNING THROUGH THE AFTERNOON. SEAS WILL BUILD TO 4-7 FT AND WAVES IN THE BAY WILL BE 4-5 FT DURING THIS TIMEFRAME. STRONG SCA CONDITIONS WILL DEVELOP AROUND DAYBREAK OVER THE REST OF CHES BAY...ERN VA RIVERS AND NRN COAST WATERS FROM FENWICK ISLAND TO PARRAMORE ISLAND AND SCA FLAGS CONTINUE FOR THESE AREAS. N WINDS GENERALLY 20-25 KT WITH GUSTS TO AROUND 30 KT WILL REMAIN ELEVATED THROUGH THE AFTERNOON BEFORE TAPERING OFF THROUGH THE EVENING. SEAS WILL BUILD TO 4-6 FT AND WAVES TO 4 FT DURING THIS TIME. HIGH PRESSURE THEN BUILDS INTO THE AREA THURSDAY NIGHT AND NW-N WINDS WILL BECOME LIGHT (AOB 15 KT) THROUGH FRIDAY. HIGH PRESSURE WILL SHIFT EAST AND PUSH OFFSHORE FRIDAY AFTERNOON AND SOUTHERLY FLOW WILL DEVELOP. A LOW PRESSURE SYSTEM OVER THE GREAT LAKES THEN TRACKS INTO THE MID ATLANTIC REGION FRIDAY NIGHT. ONCE IT MOVES OFFSHORE...IT WILL DEEPEN AND RESULT IN YET ANOTHER CAA SURGE LATE FRIDAY NIGHT INTO SATURDAY. GALE FORCE GUSTS MAY BE POSSIBLE ON SATURDAY. && .HYDROLOGY... FLOOD WARNINGS REMAIN IN EFFECT FOR THE BLACKWATER RIVER ABOVE FRANKLIN AND THE NOTTOWAY RIVER AT SEBRELL. BOTH RIVERS CONTINUE TO TREND DOWNWARD. SEE LATEST FLSAKQ/FLWAKQ FOR DETAILS. && .CLIMATE... AT RICHMOND...TODAY`S HIGH WAS ABOVE 32 F...NOW MAKING IT 732 CONSECUTIVE DAYS WITH A HIGH ABOVE 32 F (AND STILL COUNTING). THE PREVIOUS LONGEST STREAK HAD BEEN 730 DAYS (12/27/1948 TO 12/26/1950). IT WILL BE CLOSE THURSDAY AS THE LATEST FORECAST IS FOR HIGHS NEAR 32 F. NOTE: NORFOLK HAS SET NO RECORDS WITH REGARD TO THESE CRITERIA. WELL BELOW AVERAGE TEMPERATURES CONTINUE THURS BUT STILL NOT GOING TO CHALLENGE ANY RECORDS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR MDZ021>025. NC...NONE. VA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ049-063-064-072>078-083>086-099-100. MARINE...GALE WARNING UNTIL 6 PM EST THIS EVENING FOR ANZ634-654-656- 658. SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 1 AM EST FRIDAY FOR ANZ650-652. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ635>638. SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR ANZ630>632. GALE WARNING UNTIL 6 PM EST THIS EVENING FOR ANZ633. && $$ SYNOPSIS...ALB/JDM NEAR TERM...AJZ SHORT TERM...AJZ/JDM LONG TERM...TMG AVIATION...MAS/TMG/DAP MARINE...BMD HYDROLOGY...AKQ CLIMATE...AKQ
AREA FORECAST DISCUSSION
NWS RALEIGH NC
336 AM EST THU JAN 24 2013 .SYNOPSIS... AN ARCTIC COLD FRONT WILL USHER STRONG HIGH PRESSURE INTO THE CAROLINAS TODAY AND TONIGHT. A COMPLEX LOW PRESSURE SYSTEM WILL TRACK EAST ACROSS THE REGION ON FRIDAY. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 325 AM THURSDAY... TODAY: A POTENT UPPER LEVEL TROUGH OVER THE LOWER GREAT LAKES AT 06Z WILL DIG SOUTHEAST OFFSHORE THE MID-ATLANTIC COAST BETWEEN 12-18Z TODAY. AN ATTENDANT CLIPPER LOW WILL TRACK RAPIDLY EAST THROUGH NC/VA BETWEEN 06-12Z...PROGRESSING OFFSHORE AFTER SUNRISE. PRONOUNCED SUBSIDENCE IN THE WAKE OF THE UPPER LEVEL TROUGH WILL RESULT IN STRONG PRESSURE RISES OVER THE OH VALLEY AND MID-ATLANTIC THIS MORNING...DRIVING AN ARCTIC COLD FRONT RAPIDLY SOUTHWARD THROUGH CENTRAL NC BETWEEN 12-15Z. PRESSURE RISES AS GREAT AS 5-7 MB IN 3-HR ARE PROGGED OVER CENTRAL NC IN THE WAKE OF THE FRONT BETWEEN ROUGHLY 14-17Z...AND THE 06Z RAP INDICATES LOW-LEVEL FLOW BETWEEN 30-40 KT AT THE BEGINNING OF THAT TIME-FRAME (STRONGEST SE COASTAL PLAIN) WHEN THE MIXED LAYER WILL BE RAPIDLY DEEPENING IN ASSOC/W THE ONSET OF STRONG COLD ADVECTION. EXPECT STRONG NORTHERLY WINDS FOR A FEW HOURS IN THE IMMEDIATE WAKE OF THE FRONT...WITH PEAK SUSTAINED WINDS AS HIGH AS 20-30 MPH AND GUSTS AS HIGH AS 35-40 MPH FOR A BRIEF PERIOD...ESPECIALLY ACROSS PORTIONS OF THE SANDHILLS (CUMBERLAND) AND SE COASTAL PLAIN (WAYNE/SAMPSON). GIVEN A STRONG FRONTAL PASSAGE BY MID MORNING...WITH 1000-850 THICKNESSES PLUMMETING TO 1255-1265 METERS AND H85 TEMPS DECREASING TO -12 TO -15C BY MID AFTERNOON... EXPECT THAT TEMPS WILL STRUGGLE TO RISE AT ALL DURING THE DAY. WILL INDICATE HIGHS RANGING FROM THE LOWER 30S NORTH TO MID/UPPER 30S SOUTH. THE BEST FORCING ASSOC/W THE UPPER LEVEL WAVE WILL REMAIN NORTH OF CENTRAL NC THIS MORNING...OVER SOUTHEAST VA AND THE DELMARVA. H85 FRONTOGENESIS WILL STRENGTHEN OVER THE NORTHERN PIEDMONT BETWEEN 09-12Z...CONTRIBUTING TO OVERCAST CLOUD COVER WITH CEILINGS 3500-5000 FT AGL NORTH OF HWY 64. HOWEVER...THE ONSET OF LOW-LEVEL COLD ADVECTION WILL HELP TO `CANCEL OUT` FORCING ASSOC/W FRONTOGENESIS...AND A RELATIVELY DRY BOUNDARY LAYER WILL PROVIDE A FURTHER BARRIER FOR ANY LIGHT PRECIPITATION TO MAKE IT TO THE GROUND. INTERESTINGLY...H85 COLD ADVECTION WILL BE SO STRONG THAT TEMPS AT THAT LEVEL WILL FALL WITHIN THE ICE NUCLEATION ZONE (-12 TO -15C) NORTH OF HWY 64 THIS AFTERNOON...AND FCST SOUNDINGS SHOW A POTENTIAL FOR VERY SHALLOW DESTABILIZATION BETWEEN 17-21Z IN THE NE COASTAL PLAIN WHERE NORTHERLY FLOW WILL ADVECT LOW-LEVEL MOISTURE SOUTHWARD FROM THE MID-ATLANTIC COAST INTO EASTERN PORTIONS OF NC. AS A RESULT...IT IS POSSIBLE THAT ISOLD SNOW SHOWERS COULD DEVELOP OVER NORTHEASTERN NC THIS AFTERNOON. WITH THIS IN MIND...WILL INDICATE A SLIGHT CHANCE OF SHOWER SHOWERS OVER WARREN/HALIFAX AND EDGECOMBE COUNTIES BETWEEN 17-21Z...CONSISTENT WITH SIMULATED REFLECTIVITY OUTPUT FROM THE 00Z HIGH RES WRF-NMM. TONIGHT: EXPECT CLEAR SKIES OVERNIGHT AS ARCTIC HIGH PRESSURE BUILDS DIRECTLY OVER CENTRAL NC. LOWS WILL BE DRIVEN BY A COMBINATION OF COLD ADVECTION (EARLY ON) AND RADIATIONAL COOLING. WILL INDICATE LOWS RANGING FROM THE MID/UPPER TEENS TO LOWER 20S. -VINCENT && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... AS OF 240 AM THURSDAY... ...A LIGHT WINTRY MIX STILL POSSIBLE FRIDAY AND FRIDAY EVENING... THE TREND OF THE MODELS CONTINUES TO BE TOWARD A FLATTER MID/UPPER WAVE SOLUTION AND VERY LIGHT QPF... FOR FRIDAY AND FRIDAY EVENING AS THE SYSTEM MOVES THROUGH THE TENNESSEE AND LOWER OHIO VALLEY REGION ACROSS THE APPALACHIANS TO THE MID-ATLANTIC COAST. VERY COLD ARCTIC AIR WILL BE IN PLACE. HOWEVER... MOISTURE WILL BE LACKING FOR A SIGNIFICANT WINTER STORM. YET... WITH SUCH COLD AIR IN PLACE FRIDAY BEFORE THE LIGHT PRECIPITATION EVENT UNFOLDS... THIS COULD TURN OUT TO BE A MINIMAL PRECIPITATION / BUT HIGH IMPACT EVENT (I.E. THE 19JAN2005 LIGHT SNOW / HIGH IMPACT EVENT)... WHEN RDU MEASURED 1 INCH OF SNOW WITH 0.04 LIQUID EQUIVALENT / WITH TEMPERATURES IN THE MID 20S DURING THE AFTERNOON. THE LATEST MODELS CONTINUE TO INDICATE LOW QPF IN THE RANGE OF 0.1 TO 0.2 OF AN INCH... WITH MOST ENSEMBLE MEMBERS IN THE 0.05 TO 0.15 RANGE. THE MAJORITY OF THE PRECIPITATION TIMING IS FORECAST TO BE IN THE LATE MORNING OR EARLY AFTERNOON BEGIN TIME... EXCEPT DURING THE AFTERNOON IN THE SOUTHEAST... ENDING QUICKLY BY LATE AFTERNOON OR VERY EARLY EVENING. ALTHOUGH THE MODEL 1000/850 AND 850/700 THICKNESS FORECASTS CONTINUE TO SHOW DECENT SPREAD... THE FAVORED 00Z/EC CONTINUES TO INDICATE THE PREDOMINATE P-TYPE TO BE LIGHT SNOW NW (1280/1535M THICKNESSES) ...LIGHT SNOW WITH SLEET IN THE I-64 CORRIDOR (PARTIALS IN THE 1280S AND 1540S - ENDING WITH 1300 AND 1550 OR SO). SURFACE WET BULB FORECASTS KEEP TEMPERATURES IN THE 20S ALL DAY FROM RALEIGH WEST AND NORTH THROUGH THE PIEDMONT INTO THE BLUE RIDGE. THIS WILL BE THE AREA WHERE MEASURABLE SNOW AND SLEET IS FAVORED... WITH A CHANGE-OVER TO LIGHT FREEZING RAIN OR FREEZING DRIZZLE BY SUNSET OR SO (AS WE LOSE SATURATION IN THE ICE NUCLEATION ZONE ALOFT). SNOWFALL ACCUMULATIONS OF AROUND AN INCH APPEAR POSSIBLE. THIS IS WHERE A WINTER WEATHER ADVISORY WILL LIKELY BE NEEDED FRIDAY INTO FRIDAY EVENING IN LATER FORECASTS (ASSUMING THE MODELS DO NOT COMPLETELY DRY UP). IN THE CORRIDOR FROM THE FAR SOUTHERN PIEDMONT... NORTHERN SANDHILLS AND MUCH OF THE CENTRAL COASTAL PLAIN... MAINLY TO THE NORTH OF A LINE FROM LAURINBURG TO FAYETTEVILLE TO GOLDSBORO / SOUTH OF 1-64 SHOULD BEGIN WITH LIGHT SNOW/SLEET WITH A CHANGE-OVER TO LIGHT FREEZING RAIN WITH TRACE SNOW/SLEET (PREDOMINATE P-TYPES). SURFACE WET BULBS HERE ARE FORECAST TO REACH NEAR 32... PLACING THIS REGION IN LIKELY ADVISORY CRITERIA AS WELL. TO THE EAST AND SOUTH OF LAURINBURG TO FAYETTEVILLE TO GOLDSBORO... A COLD LIGHT RAIN MIXED WITH SLEET IS EXPECTED WITH WET BULBS 33-34 OR SO DURING THE AFTERNOON. BOTTOM LINE... DUE TO THE EXPECTED LIGHT NATURE OF THE PRECIPITATION EPISODE AND THE VERY COLD AIR IN PLACE FRIDAY INTO FRIDAY EVENING... THIS COULD VERY WELL TURN OUT TO BE A LOW PRECIPITATION... YET RATHER HIGH IMPACT EVENT. MODEL TRENDS CONTINUE TO DAMPEN THE WAVE AND LESSEN THE QPF WITH TIME... WHICH MAKES THIS ONLY A LOW TO MODERATE CONFIDENCE FORECAST FOR AMOUNTS. P-TYPE AND COLD AIR ARE HIGH CONFIDENCE... QPF IS LOW CONFIDENCE. CLOUDY AND COLD FRIDAY WITH LIGHT SNOW LIKELY NW... LIGHT SNOW/SLEET CENTRAL... AND MOSTLY LIGHT RAIN SE LATE MORNING THROUGH THE AFTERNOON. HIGHS 28 TO 35. FRIDAY NIGHT... PATCHY FREEZING RAIN/FREEZING DRIZZLE POSSIBLE EARLY... THEN CLEARING LATE. COLD WITH POTENTIAL BLACK ICE. LOWS IN THE 20S. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 200 AM THURSDAY... SATURDAY AND SUNDAY: ANOTHER MODIFIED ARCTIC AIR MASS DRIVEN BY A 1035+ SURFACE HIGH WILL DIVE SE ACROSS OUR REGION. THE COLDEST NIGHT WILL LIKELY BE SATURDAY NIGHT... ALTHOUGH SUNDAY NIGHT WILL BE NEARLY AS COLD... BUT WITH LIGHTER WINDS. EXPECT MOSTLY CLEAR SKIES WITH LOWS IN THE 15-20 RANGE. HIGHS IN THE MID 30S TO MID 40S NW TO SE. A STOUT WARMING TREND WILL BEGIN MONDAY... THEN BE FELT IN FULL FORCE BY TUE-WED. THE ARCTIC HIGH SHIFTS QUICKLY OFFSHORE MONDAY... FOLLOWED BY A MODERATING SW FLOW. HIGHS SHOULD SHOOT UP QUICKLY INTO THE MID 50S TO LOWER 60S MONDAY... AND REACH THE 60S TUE-WED. MUCH MILDER NIGHTS ARE EXPECTED AS WELL WITH LOWS IN THE MID 30S TO LOWER 40S BY TUE AND IN THE 40S WEDNESDAY. THE NEXT CHANCE OF RAIN APPEARS TO BE WEDNESDAY AS A COLD FRONT APPROACHES FROM THE WEST. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 215 AM THURSDAY... 24-HR TAF PERIOD: VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. A POSSIBLE EXCEPTION WILL BE THE RWI TERMINAL WHERE A BRIEF PERIOD OF MVFR CEILINGS WILL BE POSSIBLE BETWEEN 15-20Z. THE BIGGEST AVIATION CONCERN WILL BE STRONG NORTHERLY WINDS FOR SEVERAL HOURS IN THE WAKE OF A COLD FRONTAL PASSAGE EXPECTED TO OCCUR BETWEEN 12-14Z THIS MORNING...EARLIEST AT THE INT/GSO TERMINALS AND LATEST AT THE FAY TERMINAL. GIVEN STRONG PRESSURE RISES AND 30-40 KT FLOW IN A RAPIDLY DEEPENING MIXED LAYER BEHIND THE FRONT...EXPECT PEAK SUSTAINED WINDS OUT OF THE N/NNW AT 15-25 KT WITH GUSTS AS HIGH AS 30-35 KT IN THE IMMEDIATE 2-4 HOURS (BETWEEN 14-18Z) POST FROPA. WINDS WILL GRADUALLY WEAKEN TO 10-15 KT BY 21Z THIS AFTERNOON...BECOMING CALM BY 00Z. LOOKING AHEAD: DETERIORATING CONDITIONS ARE EXPECTED DURING THE DAY FRIDAY IN ASSOCIATION WITH A WEAK LOW PRESSURE SYSTEM MOVING EAST ACROSS THE REGION. EXPECT THAT CEILINGS WILL LOWER INTO THE MVFR CATEGORY EVERYWHERE BETWEEN 15-21Z FRI (EARLIEST INT/GSO AND LATEST FAY/RWI)...WITH LIGHT PRECIP AND POTENTIALLY IFR/LIFR CONDITIONS ASSOCIATED WITH A COLD AIR DAMMING WEDGE DURING THE LATE AFTERNOON AND EVENING. A WINTRY MIX IS EXPECTED AT THE INT/GSO/RDU/RWI TERMINALS...AND IFR/LIFR CONDITIONS ASSOCIATED WITH THE CAD WEDGE WOULD BE UNLIKELY TO IMPROVE UNTIL SATURDAY WHEN ARCTIC HIGH PRESSURE BUILDS INTO THE CAROLINAS. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...BADGETT LONG TERM...BADGETT AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
114 AM EST THU JAN 24 2013 .SYNOPSIS... COOL CANADIAN HIGH PRESSURE WILL CONTINUE OVER THE EASTERN STATES TODAY. THIS HIGH WILL MOVE OFF THE EAST COAST EARLY FRIDAY AS A COLD FRONT CROSSES TENNESSEE REACHING THE NORTH CAROLINA MOUNTAINS FRIDAY AFTERNOON. ANOTHER CANADIAN HIGH PRESSURE WILL DOMINATE OUR WEATHER THIS WEEKEND AND EARLY NEXT WEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 1245 AM EST THURSDAY...HAVE MADE MINOR ADJUSTMENTS TO TEMPERATURES AND DEW POINTS PER LATEST OBS. OTHERWISE...THE FORECAST IS ON TRACK. AS OF 945 PM...THE 00Z NAM AND 21Z SREF HAVE BACKED OFF ON THE DEVELOPMENT OF PRECIP OVERNIGHT WITH THE WEAK CLIPPER SYSTEM MOVING THRU. THE LAST SEVERAL RAP RUNS HAVE BEEN DRY...BUT THE 17Z LOCAL WRF-ARW STILL HAVE SOME PRECIP...ALBEIT VERY LIGHT. THESE TRENDS APPEAR TO BE VALID AS SAT PIX ONLY NOW SHOWING SOME LOW CLOUDS FORMING TO OUR NW. THEREFORE...HAVE FOLLOWED THE TRENDS AND BACKED OFF ON PRECIP FROM THE WWA FORCING AHEAD OF THE SYSTEM...BUT KEEP PRECIP IN THE NW FLOW FORCING BEHIND THE SYSTEM. THIS MEANS ONLY A SMALL CHC OF VERY LIGHT FREEZING RAIN WITH SNOW BEING THE MAIN P-TYPE. IN ADDITION...WENT WITH THE P-TYPE NOMOGRAM METHOD OF CREATING WX GRIDS INSTEAD OF TOP DOWN. THE NOMOGRAM SEEMS TO CAPTURE THE PREVIOUS AND CURRENT THINKING OF FZRA TURNING TO SN BETTER THAN THE TOP DOWN WHICH KEEPS MORE WIDESPREAD FZRA IN LONGER. OF COURSE...GIVEN THE LACK OF PRECIP UPSTREAM...THIS COULD ALL JUST BE AN EXERCISE IN FUTILITY. HAVE BACKED OFF ON QPF AS WELL GIVEN THE LACK OF PRECIP UPSTREAM AND LATEST MDL GUIDANCE. THIS STILL GIVES A TRACE OF GLAZE IN THE HIGHEST ELEVATIONS AND A DUSTING OF SNOW. GIVEN THE OVERALL TRENDS AND LACK OF CONFIDENCE...IT STILL SEEMS AN ADV IS NOT WARRANTED. THEREFORE...WILL JUST LET THE FORECAST SPEAK FOR ITSELF WITH A BRIEF PERIOD OF POTENTIAL WINTRY PRECIP WITH LITTLE TO NO ACCUM. HAD TO DROP LOWS ACROSS MUCH OF THE AREA AS TEMPS WERE RUNNING COOLER THAN NORMAL. IT LOOKS LIKE WINDS ARE PICKING UP ACROSS THE NRN MTNS...SO THE WIND ADV STILL SEEMS WELL PLACED. AS OF 645 PM...18Z MDLS CONTINUE TO SHOW PREVIOUS TRENDS OF WWA FORCED PRECIP DEVELOPING ACROSS THE MTNS LATE THIS EVENING THEN BECOMING DOMINATED BY NW FLOW PROCESSES BY MORNING. THEREFORE...THE FCST POP AND P-TYPE TRENDS STILL LOOK GOOD. STILL EXPECT ONLY VERY LIGHT PRECIP AMOUNTS...SO NO WINTER WX ADV IS EXPECTED. MAIN UPDATES WERE FOR CURRENT CONDITIONS. PREVIOUS DISCUSSION...A SHORT WAVE TROUGH WILL DIG SOUTHEAST TOWARD THE OHIO VALLEY AND MID-ATLANTIC THIS EVENING...DEEPENING THE MEAN LONG WAVE TROUGH OVER THE EASTERN CONUS AND REINFORCING THE UNSEASONABLY COOL AIR MASS WITH ANOTHER (MOSTLY DRY) COLD FRONT. HOWEVER...A WAA PATTERN DEVELOPING ACROSS THE TENN VALLEY WILL RESULT IN SOME ENHANCED LOW LEVEL MOISTURE AHEAD OF THE FRONT. THIS WILL BE AUGMENTED ACROSS THE WESTERN MOUNTAINS BY A STRONG WESTERLY LOW LEVEL FLOW. THE FORCING TONIGHT WILL REMAIN WEAK...LIMITED TO WEAK WAA AND A BIT OF AN UPSLOPE COMPONENT ALONG THE SPINE OF THE APPALACHIANS...AND MOISTURE WILL BE SHALLOW. THEREFORE...POPS WILL GENERALLY BE CONFINED TO THE COUNTIES BORDERING TENN...AND WILL BE LIMITED TO THE 30-50 RANGE. P-TYPE IS SOMEWHAT PROBLEMATIC. TEMPS IN THE MOIST LAYER DO NOT FALL BELOW -8 C UNTIL COLD ADVECTION OVERTAKES THE AREA TOWARD 12Z. THIS DOES NOT ALWAYS TRANSLATE TO A LACK OF SNOW DURING NW FLOW EVENTS (MAINLY DUE TO THE CONVECTIVE NATURE OF THOSE EVENTS). HOWEVER...THE /WARM SIDE/ OF TONIGHT/S EVENT WILL NOT BE A TRUE NW FLOW REGIME... SO I THINK THIS IS A CASE IN WHICH -FZRA OR -FZDZ WILL BE THE PRIMARY P-TYPE...UNTIL THE COLD FRONT SWEEPS THROUGH THE AREA... AFTER WHICH WE WILL SEE A TRANSITION TO A BRIEF NW FLOW SNOW EVENT. PRECIP RATES AND BRIEF DURATION OF THE EVENT SHOULD RESULT IN VERY LIGHT ICE/SNOW ACCUMS. TRAVEL PROBLEMS COULD ARISE IF WE SEE A COUPLE OF HOURS OF FREEZING DRIZZLE...WHICH COULD POTENTIALLY MAKE THE ROADS A MESS IN AREAS RIGHT ALONG THE STATE LINE. THIS IS POSSIBLE...BUT I/M NOT CONFIDENT ENOUGH TO ISSUE ANY PRODUCTS ATTM. WE WILL CONTINUE TO MENTION THIS IN THE HWO. THE OTHER CONCERN WILL BE THE WIND...AS H8 WINDS TURN TOWARD THE NW TOWARD DAYBREAK AND STRENGTHEN IN THE STRONG COLD ADVECTION. WINDS AT THE TOP OF THE MIXED LAYER INCREASE TO 45-55 KT ACROSS MUCH OF THE MTNS AS A SURFACE LOW DEEPENS OFF THE NC COAST. HOWEVER...THE SURFACE GRADIENT ACROSS THE MTNS NEVER EXCEEDS 5 OR 6 MB. WHILE THIS DOES NOT FAVOR A HIGH WIND EVENT...A WIND ADVISORY SEEMS PRUDENT FOR THE NORTHERN MTNS AND HIGH ELEVATIONS OF THE NORTHERN FOOTHILLS LATE TONIGHT AND TOMORROW MORNING. INCREASING CLOUDS AND PERSISTENT MIXING WILL RESULT IN MIN TEMPS MUCH CLOSER TO NORMAL THAN WE HAVE SEEN THE PAST COUPLE OF MORNINGS. DESPITE CLEARING SKIES DURING THE AFTERNOON THURSDAY...MAX TEMPS WILL BE COOLER THAN TODAY/S READINGS (MUCH COOLER OVER THE MTNS) OWING TO THE RESURGENCE OF COLD AIR. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... AS OF MIDDAY WED...NOT MUCH GOING ON IN THE UPPER ATMOSPHERE TO START THE PERIOD AT 00Z FRI...WITH A PRONOUNCED TROUGH SLIDING OFF INTO THE ATLANTIC LEAVING QUASI-ZONAL FLOW IN PLACE ACROSS THE EAST BEFORE NEXT TROUGH MOVES FROM THE NORTHERN PLAINS OVER THE MID-ATLANTIC REGION LATE IN THE SHORT TERM PERIOD. MOST OF THE ACTION WILL COME FROM LOW LEVEL FORCING ASSOCIATED WITH SPRAWLING SFC HIGH SHIFTING FROM THE OHIO VALLEY ONTO THE EASTERN SEABOARD THU NIGHT SETTING UP IN-SITU CAD ACROSS THE CAROLINAS. SFC LOW DEVELOPS IN ITS WAKE OVER THE NRN PLAINS AT THAT TIME...MAGNIFYING SOUTHERLY FLOW ACROSS THE LOWER MISS VALLEY AND LEADING TO DEVELOPMENT OF PRECIP IN THE BAROCLINIC ZONE THERE. THE LOW SHIFTS INTO THE GREAT LAKES REGION OVERNIGHT THU NIGHT PULLING THE BEST ISENTROPIC LIFT AND MOISTURE ADVECTION INTO THE TENN VALLEY BY EARLY FRI MORNING. AS NOTED YESTERDAY...NAM IS FIRST TO BRING PRECIP INTO OUR SW MTNS WITH ACCUMULATIONS ALREADY BY DAYBREAK FRI. HOWEVER THE ISENTROPIC LIFT WITH LOW CONDENSATION PRESSURE DEFICITS IS SEEN ON THE GFS/EC PRIOR TO THAT TIME SO I FAVOR THE EARLY START. THE RELATIVELY RAPID MOVEMENT OF THE LOW MEANS THE PRECIP SHOULD SPREAD EAST QUICKLY AND NOT BE AN ESPECIALLY LONG DURATION EVENT. QPF VALUES ARE HIGHEST FROM THE NAM...WHICH IS A LITTLE SURPRISING GIVEN THE SLIGHTLY HIGHER PWATS SEEN ON THE GFS. FOR THE MOST PART...FAVORED A BLEND OF HPC AND GFS GUIDANCE WHICH WERE FAIRLY CLOSELY MATCHED. THE TRACK OF THE LOW IS SUCH THAT IT COULD ERODE THE CAD WEDGE...AND THE MODELS SHOW THIS. HOWEVER GIVEN THE PRE-EXISTING COLD AIR MASS PRESENTLY IN PLACE AND PAST EXPERIENCE WITH HIGH PRESSURE CENTERS FOLLOWING THIS TRACK...THE WEDGE COULD HOLD STRONG. THE NAM HOLDS ON TO THE WEDGE THE LONGEST OF THE OPNL MODELS AND ALSO HAS THE COOLEST RAW TEMPS. THAT SEEMS LIKE THE MOST PLAUSIBLE SOLUTION SO I FAVORED A BLEND OF RAW NAM AND NAM MOS TEMPS FRIDAY...ALONG WITH NAM THERMAL PROFILES THROUGH THE EVENT. WITH THE STRONG WARM ADVECTION OVERRIDING THE COLD WEDGE...MOST OF THE CWFA LOOKS TO GET MOSTLY FREEZING RAIN. SOME SLEET WILL OCCUR FURTHER NORTH WHERE THE WARM NOSE WILL NOT BE QUITE AS STRONG PER BOURGOUIN PTYPE TECHNIQUE...WITH MOSTLY TO ALL SNOW ACROSS OUR NORTHERN TIER OF COUNTIES. AS THE SFC LOW MOVES INTO THE MID-ATLANTIC AND TURNS FLOW WESTERLY ACROSS THE REGION...MOISTURE AND WARMER AIR ARE PUSHED OUT OF THE PIEDMONT BY FRI EVENING. UPSLOPE WILL ALLOW CONTINUING PRECIP IN THE MTNS. THE SHALLOW MOIST LAYER IS TOO WARM FOR ICE NUCLEATION SO FREEZING RAIN SHOULD RESULT...THOUGH WITH ONLY VERY SMALL ADDITIONAL ACCUMULATION. SAID PCPN IS EXPECTED TO BE CONFINED TO PRIME UPSLOPE AREAS IN THE NRN NC MTNS AND DIMINISH BY MID MORNING SAT. HIGHS WILL REBOUND A BIT OVER THE PIEDMONT GIVEN THE SUNSHINE...BUT STILL SEVERAL DEGREES BELOW NORMAL. THERE IS RELATIVELY HIGH CONFIDENCE IN THE FRIDAY EVENT PRODUCING WINTER WX ACROSS THE REGION. THE SOUTHWEST MOUNTAINS LOOK TO RECEIVE ICE ACCUMULATION OF A QUARTER INCH OR MORE ESPECIALLY AT HIGHER ELEVATIONS. TOGETHER THESE POINTS WARRANT A WINTER STORM WATCH FOR THAT AREA. TEMPERATURES REMAIN SOMEWHAT CRITICAL DURING THE DAY FRIDAY. IF TEMPS ARE ABLE TO WARM SUFFICIENTLY BEFORE THE BULK OF THE PRECIP ARRIVES...THE AREA MAY SEE LARGELY RAIN AND ICE ACCUMS MAY BE LIMITED. THE CURRENT FCST TEMP AND PRECIP TRENDS SUPPORT THE WATCH DESPITE HAVING AFTERNOON TEMPS ABOVE FREEZING AND RAIN AT THAT TIME. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AT 1430 EST WEDNESDAY...AN UPPER TROUGH WILL PROGRESS AWAY FROM THE COAST SATURDAY NIGHT...WHILE AN UPPER RIDGE AMPLIFIES OVER THE PLAINS. THIS RIDGE SLOWLY PROGRESSES TO THE EASTERN USA BY EARLY NEXT WEEK. SURFACE HIGH PRESSURE BEHIND A DEPARTING COLD FRONT WILL MOVE TO THE APPALACHIANS BY SUNDAY...THEN TO THE MID ATLANTIC COAST BY MONDAY. MOIST GULF INFLOW ON THE BACK SIDE OF THIS HIGH WILL REACH OUR AREA MONDAY AND TUESDAY...WHILE THE HIGH MOVES OFFSHORE. GULF INFLOW WILL DIMINISH WEDNESDAY WITH A WEAKENING PRESSURE GRADIENT...WHILE A COLD FRONT APPROACHES FORM THE NORTHWEST. THE FRONT CROSSES OUR AREA DURING THE DAY...FOLLOWED BY MOIST NW FLOW INTO THE NC MOUNTAINS...WHERE TEMPERATURES SHOULD STILL SUPPORT LIQUID PRECIPITATION IN THE AFTERNOON. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AT KCLT AND OTHER PIEDMONT/FOOTHILLS TERMINALS...VFR THROUGH THE TAF PERIOD. A DRY COLD FRONT WILL SLIP SOUTHEAST THROUGH THE AREA EARLY THURSDAY MORNING. AHEAD OF AN APPROACHING FRONT...MOISTURE WILL INCREASE OVERNIGHT HOURS. MODEL SOUNDING/TIME HEIGHTS SUGGEST CONSIDERABLE AMOUNTS OF HIGH CLOUDS WILL SPREAD OVERHEAD THROUGH THUR MORNING WITH SOME LOW VFR CEILING STRATUS POSSIBLE OVER THE NORTHERN NC PIEDMONT. WINDS WILL VEER FROM SW TO NW/N IN THE WAKE OF THE FRONTAL PASSAGE. AS CANADIAN HIGH PRESSURE BUILDS BEHIND IN THE FRONT THURSDAY...GUSTY N WINDS OF 15-20KT WILL OCCUR LATE THUR MORNING THROUGH MIDDAY MAINLY OVER THE NC PIEDMONT AFFECTING KCLT AND KHKY. GUSTS DIMINISH BY LATE AFTERNOON WITH WINDS BECOMING NE. SKY WILL REMAIN MOSTLY CLEAR THUR INTO THUR NIGHT. AT KAVL...MOISTURE INCREASING AHEAD OF A COLD FRONT SHOULD RESULT IN LOW VFR STRATOCU. NW GUSTS AROUND 20 KTS ARE EXPECTED BY DAYBREAK WITH 30 KT GUSTS COMMON AFTER SUNRISE THURSDAY. CLOUDS SHOULD GRADUALLY DISSIPATE BY MIDDAY THURSDAY WITH GUSTY N WINDS DIMINISHING BY EVENING. OUTLOOK...A COLD FRONT WILL MOVE THROUGH FRIDAY WITH FLIGHT RESTRICTIONS AND A WINTRY MIX LIKELY. DRY HIGH PRESSURE WILL RETURN BY SATURDAY WITH MORE VFR CONDITIONS...PERSISTING INTO MONDAY. AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE CATEGORY IS AVAILABLE AT THE FOLLOWING LINK (USE LOWER CASE)... WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .FIRE WEATHER... FUEL MOISTURE AND MINIMUM RELATIVE HUMIDITY VALUES WILL BE CLOSE TO FIRE DANGER STATEMENT CRITERIA IN NE GA ON THURSDAY. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING FOR GAZ010-017. NC...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING FOR NCZ051-052-058-059-062>065. WIND ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NCZ033-049-050- 501-503-505. SC...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING FOR SCZ001>003. && $$ SYNOPSIS...JPT NEAR TERM...JOH/RWH SHORT TERM...WIMBERLEY LONG TERM...JAT AVIATION...JOH FIRE WEATHER...
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
108 AM EST THU JAN 24 2013 .SYNOPSIS... COOL CANADIAN HIGH PRESSURE WILL CONTINUE OVER THE EASTERN STATES TODAY. THIS HIGH WILL MOVE OFF THE EAST COAST EARLY FRIDAY AS A COLD FRONT CROSSES TENNESSEE REACHING THE NORTH CAROLINA MOUNTAINS FRIDAY AFTERNOON. ANOTHER CANADIAN HIGH PRESSURE WILL DOMINATE OUR WEATHER THIS WEEKEND AND EARLY NEXT WEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 945 PM...THE 00Z NAM AND 21Z SREF HAVE BACKED OFF ON THE DEVELOPMENT OF PRECIP OVERNIGHT WITH THE WEAK CLIPPER SYSTEM MOVING THRU. THE LAST SEVERAL RAP RUNS HAVE BEEN DRY...BUT THE 17Z LOCAL WRF-ARW STILL HAVE SOME PRECIP...ALBEIT VERY LIGHT. THESE TRENDS APPEAR TO BE VALID AS SAT PIX ONLY NOW SHOWING SOME LOW CLOUDS FORMING TO OUR NW. THEREFORE...HAVE FOLLOWED THE TRENDS AND BACKED OFF ON PRECIP FROM THE WWA FORCING AHEAD OF THE SYSTEM...BUT KEEP PRECIP IN THE NW FLOW FORCING BEHIND THE SYSTEM. THIS MEANS ONLY A SMALL CHC OF VERY LIGHT FREEZING RAIN WITH SNOW BEING THE MAIN P-TYPE. IN ADDITION...WENT WITH THE P-TYPE NOMOGRAM METHOD OF CREATING WX GRIDS INSTEAD OF TOP DOWN. THE NOMOGRAM SEEMS TO CAPTURE THE PREVIOUS AND CURRENT THINKING OF FZRA TURNING TO SN BETTER THAN THE TOP DOWN WHICH KEEPS MORE WIDESPREAD FZRA IN LONGER. OF COURSE...GIVEN THE LACK OF PRECIP UPSTREAM...THIS COULD ALL JUST BE AN EXERCISE IN FUTILITY. HAVE BACKED OFF ON QPF AS WELL GIVEN THE LACK OF PRECIP UPSTREAM AND LATEST MDL GUIDANCE. THIS STILL GIVES A TRACE OF GLAZE IN THE HIGHEST ELEVATIONS AND A DUSTING OF SNOW. GIVEN THE OVERALL TRENDS AND LACK OF CONFIDENCE...IT STILL SEEMS AN ADV IS NOT WARRANTED. THEREFORE...WILL JUST LET THE FORECAST SPEAK FOR ITSELF WITH A BRIEF PERIOD OF POTENTIAL WINTRY PRECIP WITH LITTLE TO NO ACCUM. HAD TO DROP LOWS ACROSS MUCH OF THE AREA AS TEMPS WERE RUNNING COOLER THAN NORMAL. IT LOOKS LIKE WINDS ARE PICKING UP ACROSS THE NRN MTNS...SO THE WIND ADV STILL SEEMS WELL PLACED. AS OF 645 PM...18Z MDLS CONTINUE TO SHOW PREVIOUS TRENDS OF WWA FORCED PRECIP DEVELOPING ACROSS THE MTNS LATE THIS EVENING THEN BECOMING DOMINATED BY NW FLOW PROCESSES BY MORNING. THEREFORE...THE FCST POP AND P-TYPE TRENDS STILL LOOK GOOD. STILL EXPECT ONLY VERY LIGHT PRECIP AMOUNTS...SO NO WINTER WX ADV IS EXPECTED. MAIN UPDATES WERE FOR CURRENT CONDITIONS. PREVIOUS DISCUSSION...A SHORT WAVE TROUGH WILL DIG SOUTHEAST TOWARD THE OHIO VALLEY AND MID-ATLANTIC THIS EVENING...DEEPENING THE MEAN LONG WAVE TROUGH OVER THE EASTERN CONUS AND REINFORCING THE UNSEASONABLY COOL AIR MASS WITH ANOTHER (MOSTLY DRY) COLD FRONT. HOWEVER...A WAA PATTERN DEVELOPING ACROSS THE TENN VALLEY WILL RESULT IN SOME ENHANCED LOW LEVEL MOISTURE AHEAD OF THE FRONT. THIS WILL BE AUGMENTED ACROSS THE WESTERN MOUNTAINS BY A STRONG WESTERLY LOW LEVEL FLOW. THE FORCING TONIGHT WILL REMAIN WEAK...LIMITED TO WEAK WAA AND A BIT OF AN UPSLOPE COMPONENT ALONG THE SPINE OF THE APPALACHIANS...AND MOISTURE WILL BE SHALLOW. THEREFORE...POPS WILL GENERALLY BE CONFINED TO THE COUNTIES BORDERING TENN...AND WILL BE LIMITED TO THE 30-50 RANGE. P-TYPE IS SOMEWHAT PROBLEMATIC. TEMPS IN THE MOIST LAYER DO NOT FALL BELOW -8 C UNTIL COLD ADVECTION OVERTAKES THE AREA TOWARD 12Z. THIS DOES NOT ALWAYS TRANSLATE TO A LACK OF SNOW DURING NW FLOW EVENTS (MAINLY DUE TO THE CONVECTIVE NATURE OF THOSE EVENTS). HOWEVER...THE /WARM SIDE/ OF TONIGHT/S EVENT WILL NOT BE A TRUE NW FLOW REGIME... SO I THINK THIS IS A CASE IN WHICH -FZRA OR -FZDZ WILL BE THE PRIMARY P-TYPE...UNTIL THE COLD FRONT SWEEPS THROUGH THE AREA... AFTER WHICH WE WILL SEE A TRANSITION TO A BRIEF NW FLOW SNOW EVENT. PRECIP RATES AND BRIEF DURATION OF THE EVENT SHOULD RESULT IN VERY LIGHT ICE/SNOW ACCUMS. TRAVEL PROBLEMS COULD ARISE IF WE SEE A COUPLE OF HOURS OF FREEZING DRIZZLE...WHICH COULD POTENTIALLY MAKE THE ROADS A MESS IN AREAS RIGHT ALONG THE STATE LINE. THIS IS POSSIBLE...BUT I/M NOT CONFIDENT ENOUGH TO ISSUE ANY PRODUCTS ATTM. WE WILL CONTINUE TO MENTION THIS IN THE HWO. THE OTHER CONCERN WILL BE THE WIND...AS H8 WINDS TURN TOWARD THE NW TOWARD DAYBREAK AND STRENGTHEN IN THE STRONG COLD ADVECTION. WINDS AT THE TOP OF THE MIXED LAYER INCREASE TO 45-55 KT ACROSS MUCH OF THE MTNS AS A SURFACE LOW DEEPENS OFF THE NC COAST. HOWEVER...THE SURFACE GRADIENT ACROSS THE MTNS NEVER EXCEEDS 5 OR 6 MB. WHILE THIS DOES NOT FAVOR A HIGH WIND EVENT...A WIND ADVISORY SEEMS PRUDENT FOR THE NORTHERN MTNS AND HIGH ELEVATIONS OF THE NORTHERN FOOTHILLS LATE TONIGHT AND TOMORROW MORNING. INCREASING CLOUDS AND PERSISTENT MIXING WILL RESULT IN MIN TEMPS MUCH CLOSER TO NORMAL THAN WE HAVE SEEN THE PAST COUPLE OF MORNINGS. DESPITE CLEARING SKIES DURING THE AFTERNOON THURSDAY...MAX TEMPS WILL BE COOLER THAN TODAY/S READINGS (MUCH COOLER OVER THE MTNS) OWING TO THE RESURGENCE OF COLD AIR. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... AS OF MIDDAY WED...NOT MUCH GOING ON IN THE UPPER ATMOSPHERE TO START THE PERIOD AT 00Z FRI...WITH A PRONOUNCED TROUGH SLIDING OFF INTO THE ATLANTIC LEAVING QUASI-ZONAL FLOW IN PLACE ACROSS THE EAST BEFORE NEXT TROUGH MOVES FROM THE NORTHERN PLAINS OVER THE MID-ATLANTIC REGION LATE IN THE SHORT TERM PERIOD. MOST OF THE ACTION WILL COME FROM LOW LEVEL FORCING ASSOCIATED WITH SPRAWLING SFC HIGH SHIFTING FROM THE OHIO VALLEY ONTO THE EASTERN SEABOARD THU NIGHT SETTING UP IN-SITU CAD ACROSS THE CAROLINAS. SFC LOW DEVELOPS IN ITS WAKE OVER THE NRN PLAINS AT THAT TIME...MAGNIFYING SOUTHERLY FLOW ACROSS THE LOWER MISS VALLEY AND LEADING TO DEVELOPMENT OF PRECIP IN THE BAROCLINIC ZONE THERE. THE LOW SHIFTS INTO THE GREAT LAKES REGION OVERNIGHT THU NIGHT PULLING THE BEST ISENTROPIC LIFT AND MOISTURE ADVECTION INTO THE TENN VALLEY BY EARLY FRI MORNING. AS NOTED YESTERDAY...NAM IS FIRST TO BRING PRECIP INTO OUR SW MTNS WITH ACCUMULATIONS ALREADY BY DAYBREAK FRI. HOWEVER THE ISENTROPIC LIFT WITH LOW CONDENSATION PRESSURE DEFICITS IS SEEN ON THE GFS/EC PRIOR TO THAT TIME SO I FAVOR THE EARLY START. THE RELATIVELY RAPID MOVEMENT OF THE LOW MEANS THE PRECIP SHOULD SPREAD EAST QUICKLY AND NOT BE AN ESPECIALLY LONG DURATION EVENT. QPF VALUES ARE HIGHEST FROM THE NAM...WHICH IS A LITTLE SURPRISING GIVEN THE SLIGHTLY HIGHER PWATS SEEN ON THE GFS. FOR THE MOST PART...FAVORED A BLEND OF HPC AND GFS GUIDANCE WHICH WERE FAIRLY CLOSELY MATCHED. THE TRACK OF THE LOW IS SUCH THAT IT COULD ERODE THE CAD WEDGE...AND THE MODELS SHOW THIS. HOWEVER GIVEN THE PRE-EXISTING COLD AIR MASS PRESENTLY IN PLACE AND PAST EXPERIENCE WITH HIGH PRESSURE CENTERS FOLLOWING THIS TRACK...THE WEDGE COULD HOLD STRONG. THE NAM HOLDS ON TO THE WEDGE THE LONGEST OF THE OPNL MODELS AND ALSO HAS THE COOLEST RAW TEMPS. THAT SEEMS LIKE THE MOST PLAUSIBLE SOLUTION SO I FAVORED A BLEND OF RAW NAM AND NAM MOS TEMPS FRIDAY...ALONG WITH NAM THERMAL PROFILES THROUGH THE EVENT. WITH THE STRONG WARM ADVECTION OVERRIDING THE COLD WEDGE...MOST OF THE CWFA LOOKS TO GET MOSTLY FREEZING RAIN. SOME SLEET WILL OCCUR FURTHER NORTH WHERE THE WARM NOSE WILL NOT BE QUITE AS STRONG PER BOURGOUIN PTYPE TECHNIQUE...WITH MOSTLY TO ALL SNOW ACROSS OUR NORTHERN TIER OF COUNTIES. AS THE SFC LOW MOVES INTO THE MID-ATLANTIC AND TURNS FLOW WESTERLY ACROSS THE REGION...MOISTURE AND WARMER AIR ARE PUSHED OUT OF THE PIEDMONT BY FRI EVENING. UPSLOPE WILL ALLOW CONTINUING PRECIP IN THE MTNS. THE SHALLOW MOIST LAYER IS TOO WARM FOR ICE NUCLEATION SO FREEZING RAIN SHOULD RESULT...THOUGH WITH ONLY VERY SMALL ADDITIONAL ACCUMULATION. SAID PCPN IS EXPECTED TO BE CONFINED TO PRIME UPSLOPE AREAS IN THE NRN NC MTNS AND DIMINISH BY MID MORNING SAT. HIGHS WILL REBOUND A BIT OVER THE PIEDMONT GIVEN THE SUNSHINE...BUT STILL SEVERAL DEGREES BELOW NORMAL. THERE IS RELATIVELY HIGH CONFIDENCE IN THE FRIDAY EVENT PRODUCING WINTER WX ACROSS THE REGION. THE SOUTHWEST MOUNTAINS LOOK TO RECEIVE ICE ACCUMULATION OF A QUARTER INCH OR MORE ESPECIALLY AT HIGHER ELEVATIONS. TOGETHER THESE POINTS WARRANT A WINTER STORM WATCH FOR THAT AREA. TEMPERATURES REMAIN SOMEWHAT CRITICAL DURING THE DAY FRIDAY. IF TEMPS ARE ABLE TO WARM SUFFICIENTLY BEFORE THE BULK OF THE PRECIP ARRIVES...THE AREA MAY SEE LARGELY RAIN AND ICE ACCUMS MAY BE LIMITED. THE CURRENT FCST TEMP AND PRECIP TRENDS SUPPORT THE WATCH DESPITE HAVING AFTERNOON TEMPS ABOVE FREEZING AND RAIN AT THAT TIME. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AT 1430 EST WEDNESDAY...AN UPPER TROUGH WILL PROGRESS AWAY FROM THE COAST SATURDAY NIGHT...WHILE AN UPPER RIDGE AMPLIFIES OVER THE PLAINS. THIS RIDGE SLOWLY PROGRESSES TO THE EASTERN USA BY EARLY NEXT WEEK. SURFACE HIGH PRESSURE BEHIND A DEPARTING COLD FRONT WILL MOVE TO THE APPALACHIANS BY SUNDAY...THEN TO THE MID ATLANTIC COAST BY MONDAY. MOIST GULF INFLOW ON THE BACK SIDE OF THIS HIGH WILL REACH OUR AREA MONDAY AND TUESDAY...WHILE THE HIGH MOVES OFFSHORE. GULF INFLOW WILL DIMINISH WEDNESDAY WITH A WEAKENING PRESSURE GRADIENT...WHILE A COLD FRONT APPROACHES FORM THE NORTHWEST. THE FRONT CROSSES OUR AREA DURING THE DAY...FOLLOWED BY MOIST NW FLOW INTO THE NC MOUNTAINS...WHERE TEMPERATURES SHOULD STILL SUPPORT LIQUID PRECIPITATION IN THE AFTERNOON. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AT KCLT AND OTHER PIEDMONT/FOOTHILLS TERMINALS...VFR THROUGH THE TAF PERIOD. A DRY COLD FRONT WILL SLIP SOUTHEAST THROUGH THE AREA EARLY THURSDAY MORNING. AHEAD OF AN APPROACHING FRONT...MOISTURE WILL INCREASE OVERNIGHT HOURS. MODEL SOUNDING/TIME HEIGHTS SUGGEST CONSIDERABLE AMOUNTS OF HIGH CLOUDS WILL SPREAD OVERHEAD THROUGH THUR MORNING WITH SOME LOW VFR CEILING STRATUS POSSIBLE OVER THE NORTHERN NC PIEDMONT. WINDS WILL VEER FROM SW TO NW/N IN THE WAKE OF THE FRONTAL PASSAGE. AS CANADIAN HIGH PRESSURE BUILDS BEHIND IN THE FRONT THURSDAY...GUSTY N WINDS OF 15-20KT WILL OCCUR LATE THUR MORNING THROUGH MIDDAY MAINLY OVER THE NC PIEDMONT AFFECTING KCLT AND KHKY. GUSTS DIMINISH BY LATE AFTERNOON WITH WINDS BECOMING NE. SKY WILL REMAIN MOSTLY CLEAR THUR INTO THUR NIGHT. AT KAVL...MOISTURE INCREASING AHEAD OF A COLD FRONT SHOULD RESULT IN LOW VFR STRATOCU. NW GUSTS AROUND 20 KTS ARE EXPECTED BY DAYBREAK WITH 30 KT GUSTS COMMON AFTER SUNRISE THURSDAY. CLOUDS SHOULD GRADUALLY DISSIPATE BY MIDDAY THURSDAY WITH GUSTY N WINDS DIMINISHING BY EVENING. OUTLOOK...A COLD FRONT WILL MOVE THROUGH FRIDAY WITH FLIGHT RESTRICTIONS AND A WINTRY MIX LIKELY. DRY HIGH PRESSURE WILL RETURN BY SATURDAY WITH MORE VFR CONDITIONS...PERSISTING INTO MONDAY. AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE CATEGORY IS AVAILABLE AT THE FOLLOWING LINK (USE LOWER CASE)... WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .FIRE WEATHER... FUEL MOISTURE AND MINIMUM RELATIVE HUMIDITY VALUES WILL BE CLOSE TO FIRE DANGER STATEMENT CRITERIA IN NE GA ON THURSDAY. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING FOR GAZ010-017. NC...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING FOR NCZ051-052-058-059-062>065. WIND ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NCZ033-049-050- 501-503-505. SC...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING FOR SCZ001>003. && $$ SYNOPSIS...JPT NEAR TERM...JDL/RWH SHORT TERM...WIMBERLEY LONG TERM...JAT AVIATION...JOH FIRE WEATHER...
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
339 AM CST THU JAN 24 2013 .DISCUSSION... UPPER LEVEL RIDGE IS NOW CENTERED SOUTHWEST OF THE AREA WITH HIGH CLOUDS STREAMING OVER THE TOP OF THE RIDGE AND INTO THE STATE. AT THE SURFACE...SOME STRATUS CLOUDS ARE NOW DEVELOPING ACROSS SOUTHEAST TEXAS...BUT ARE MOVING TO THE EAST AND NORTHEAST. SOME LOW CLOUDS WILL OCCUR OVER THE SOUTHEASTERN COUNTIES THIS MORNING...BUT SHOULD DISSIPATE BEFORE MIDDAY. IN ADDITION...THERE IS SOME SCATTERED PATCHY OF FOG ASSOCIATED WITH THE LOW CLOUDS IN SOUTHEAST TEXAS. AT THIS TIME DO NOT HAVE FOG MENTIONED IN THE GRIDS AS CURRENT THINKING IS THAT MOST OF THE FOG WILL STAY JUST OUTSIDE OUR AREA...BUT WILL UPDATE IF THE FOG BECOMES MORE WIDESPREAD. WILL ALSO BE MONITORING FOR FOG DEVELOPMENT NEAR THE RED RIVER THIS MORNING AS A COLD FRONT APPROACHES AND THE WINDS BECOME LIGHT. THE COLD FRONT HAS NOW PUSHED INTO SOUTHERN OKLAHOMA WITH TEMPERATURES IN THE 30S AND 40S BEHIND THE FRONT. THIS FRONT WILL EDGE JUST SOUTH OF THE RED RIVER TODAY...RESULTING IN MUCH COOLER TEMPERATURES ACROSS OUR NORTHERN COUNTIES. HIGH TEMPERATURES THIS AFTERNOON WILL RANGE FROM THE UPPER 50S ALONG THE RED RIVER TO NEAR 80 DEGREES IN OUR SOUTHWESTERN COUNTIES. HIGH CLOUDS ACROSS THE REGION AND SOME LOWER LEVEL CLOUDS DEVELOPING BEHIND PARTS OF THE FRONT WILL KEEP TEMPERATURES ON THE COOLER SIDE OF GUIDANCE TODAY. YESTERDAY...IT APPEARED THAT THE FRONT WOULD STALL OR EVEN RETREAT A LITTLE NEAR THE RED RIVER TONIGHT. HOWEVER...HI-RES GUIDANCE INCLUDING THE RAP AND TEXAS TECH WRF ALL SUPPORT THE NAM WHICH BEGINS TO PUSH THE FRONT SOUTH TONIGHT. WITH THE COLD TEMPERATURES THAT ARE ALREADY OCCURRING BEHIND THE FRONT...THIS SOLUTION IS THE MOST PLAUSIBLE ONE AND WILL SHOW THE FRONT SLOWLY MOVING SOUTH AFTER SUNSET. THE FRONT WILL CONTINUE MOVING SOUTH ON FRIDAY...HAVING MADE ITS WAY ALMOST ENTIRELY THROUGH THE CWA BY MIDDAY. TEMPERATURES TONIGHT WILL AGAIN BE VARIABLE WITH OVERNIGHT LOWS BEHIND THE FRONT IN THE 30S AND LOWER 40S...BUT UP TO THE UPPER 50S AHEAD OF THE FRONT. THERE IS STILL A LOW CHANCE FOR DRIZZLE OR VERY LIGHT RAIN OVER THE FAR NORTHEASTERN COUNTIES TONIGHT. FRIDAY THROUGH SATURDAY WILL CONTINUE TO BE COOL BEHIND THE FRONT. WENT WITH THE COOLER GUIDANCE ON SATURDAY ANTICIPATING MOSTLY CLOUDY SKIES AND POSSIBLY SOME ADDITIONAL LIGHT RAIN. THIS CHANCE FOR LIGHT RAIN WILL BE ASSOCIATED WITH A WEAK SHORTWAVE LIFTING NORTHEAST ACROSS THE SOUTHWEST CONUS AND INTO THE PLAINS. THE TRACK OF THIS SHORTWAVE IS SLIGHTLY FARTHER NORTH TONIGHT WITH THE BEST CHANCES FOR RAIN NORTH OF THE REGION. THEREFORE REDUCED POPS TO ONLY 20 PERCENT OF LIGHT RAIN...AND REMOVED THE POPS FROM SUNDAY AS THE SHORTWAVE WILL BE CROSSING OUT OF THE PLAINS BY THEN. AGAIN...ANY PRECIPITATION ON SATURDAY MAY LIKELY ONLY BE DRIZZLE INDUCED BY SOME ISENTROPIC LIFT OVER THE COOL SURFACE LAYER. AFTER SATURDAY...SOUTH TO SOUTHWEST FLOW IN THE LOW TO MID LEVELS OF THE ATMOSPHERE WILL RESULT IN ANOTHER WARM UP. WE WILL SEE TEMPERATURES BACK THE 70S BY MONDAY...WITH BREEZY WINDS AND MOSTLY CLOUDY SKIES. BOTH THE GFS AND ECMWF CONTINUE TO ADVERTISE A STRONGER UPPER LEVEL TROUGH MOVING THROUGH THE PLAINS AROUND THE MIDDLE OF NEXT WEEK...BUT THE LATEST ECMWF SOLUTION HAS CHANGED FROM THE PAST FEW RUNS WITH THE TROUGH NOW FARTHER NORTH AND MUCH BROADER. HOWEVER...IT STILL LOOKS LIKE NORTH AND CENTRAL TEXAS WILL HAVE A CHANCE FOR SHOWERS AND THUNDERSTORMS ON TUESDAY AS A DRYLINE AND COLD FRONT MOVE THROUGH THE REGION. SIDED WITH THE ECMWF IN THE EXTENDED BY CLEARING THE RAIN OUT WITH THE FRONT ON TUESDAY. THE REMAINDER OF THE FORECAST LOOKS DRY AS WE TRANSITION TO NORTHWEST AND/OR MORE ZONAL FLOW FOR A FEW DAYS. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 75 42 56 41 55 / 5 10 5 5 20 WACO, TX 79 53 62 44 62 / 10 10 10 10 20 PARIS, TX 56 39 53 35 53 / 10 20 10 5 20 DENTON, TX 72 40 53 38 53 / 5 10 5 5 20 MCKINNEY, TX 72 40 54 39 53 / 10 10 5 5 20 DALLAS, TX 75 43 57 42 55 / 5 10 5 5 20 TERRELL, TX 74 46 57 41 55 / 10 10 10 5 20 CORSICANA, TX 75 52 61 43 58 / 10 10 10 10 20 TEMPLE, TX 79 54 65 46 64 / 10 5 10 10 20 MINERAL WELLS, TX 73 39 56 39 54 / 5 5 0 5 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 58/82
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1104 PM CST WED JAN 23 2013 .AVIATION... HIGH CLOUDS CONTINUE TO STREAM FROM NW TO SE ACROSS NORTH TEXAS AND SURFACE WINDS REMAIN FROM THE SOUTH AROUND 5 TO 10 KNOTS. THE MAIN CONCERN OVERNIGHT WILL BE THE POTENTIAL FOR FOG/LOW CLOUDS. AS THE PREVIOUS DISCUSSION STATED...THE DEPTH OF THE MOISTURE WILL LIMIT THE THREAT FOR STRATUS. ALSO...SURFACE WINDS OF 5-10 KTS AND SW WINDS AROUND 20-25 KTS JUST OFF THE SURFACE SHOULD LIMIT THE THREAT FOR FOG. LATEST RAP SOUNDINGS INDICATE VERY LITTLE THREAT FOR RESTRICTIONS OVERNIGHT...WHILE THE NAM CONTINUES TO SHOW POSSIBLE LOW CLOUDS. A SURFACE FRONT IN OKLAHOMA WILL BE LOCATED NEAR THE RED RIVER BY DAYBREAK AND THE BEST CHANCES FOR FOG WILL BE LOCATED ALONG THIS SLOW-MOVING BOUNDARY WHERE WINDS BRIEFLY GO CALM. ADDITIONAL FOG IS LIKELY ACROSS SOUTHEAST TEXAS WHERE THE BEST MOISTURE AND LIGHTER SURFACE WINDS ARE LOCATED. JUST MADE MINOR TWEAKS TO THE PREVIOUS TAFS...AS SIGNIFICANT CHANGES WERE NOT NEEDED. FOR THE METROPLEX...WILL SHOW 6SM AND SCT004 TO HINT AT THE POSSIBILITY OF SOMETHING FORMING BY MORNING...BUT SINCE CONFIDENCE IS LOW IN THIS OUTCOME...DIDNT WANT TO PREVAIL ANY RESTRICTIONS. MOISTURE LOOKS TO BE A BIT DEEPER FOR WACO AND WILL CONTINUE THE TEMPO GROUP FROM 11-15Z...BUT LOWERED THE CEILINGS TO 400 FEET. THE CONFIDENCE IN THIS OUTCOME IS STILL NOT HIGH. ANY CIGS/VIS RESTRICTIONS SHOULD LIFT AROUND 15Z. THE FRONTAL TIMING DIFFERS BETWEEN THE GUIDANCE BUT WILL STICK WITH THE NAM/RAP GROUP WHICH SLOWLY BRINGS THE FRONT THROUGH THE METROPLEX LATE IN THE EVENING. MVFR CIGS ARE LIKELY BEHIND THE FRONT. HAMPSHIRE && .UPDATE... HAVE AMENDED SKY FORECAST FOR MORE CLOUDS IN THE EAST LATE TONIGHT AND ACROSS THE NORTH TOMORROW NEAR/BEHIND THE WEAK FRONT. TR.92 && .PREV DISCUSSION... /ISSUED 303 PM CST WED JAN 23 2013/ A WEAK COLD FRONT WILL DROP ACROSS NORTHERN AREAS OF NORTH TEXAS THURSDAY. THIS WILL PRODUCE LIGHTER WINDS THURSDAY THAN WE HAD BEEN FORECASTING EARLIER IN THE WEEK...BUT THE ONLY ASSOCIATED WEATHER WILL BE SOME LIGHT RAIN IN THE NORTHEAST THURSDAY NIGHT. THE FRONT GETS ANOTHER PUSH ON FRIDAY MORNING AND SWEEPS SOUTH ACROSS NORTH TEXAS...BUT PRECIP IS EXPECTED TO REMAIN EAST AND SOUTH OF OUR AREA. OVER THE WEEKEND...FLOW ALOFT SWITCHES FROM NORTHWEST TO SOUTHWEST AS A LOW AMPLITUDE RIDGE MOVES EAST...AND A SERIES OF DISTURBANCES ARE EXPECTED TO PRODUCE INTERVALS OF PRECIPITATION. ON SATURDAY MORNING SOME LIGHT RAIN/DRIZZLE SHOULD FALL AS MOISTURE OVERRUNS THE FRONT...AND WEAK LARGE SCALE LIFT FROM THE UPPER DISTURBANCES ON SUNDAY AND MONDAY WILL PRODUCE AREAS OF SHOWERS. AS A STRONGER TROF APPROACHES THE AREA TUESDAY...WIDESPREAD LIFT INCREASES AND LAPSE RATES STEEPEN. THUNDERSTORMS THEN ENTER THE EQUATION AS WELL. CAPE IS NOT LOOKING THAT IMPRESSIVE YET...SO THE SEVERE THREAT CURRENTLY APPEARS FAIRLY MINIMAL. TIMING AND INTENSITY OF THE UPPER TROF AS WELL AS FROPA ARE NOT YET WELL HANDLED...BUT PRE HPC AND MY OWN OBSERVATION OVER THE LAST FEW DAYS THE ECMWF/CMC HAVE HAD BETTER CONTINUITY THAN THE GFS AND I USED THEIR TIMING FOR THE FROPA AND END OF PRECIP TUESDAY NIGHT. 84 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 52 74 49 55 42 / 0 5 10 5 20 WACO, TX 54 77 54 59 45 / 0 10 10 10 20 PARIS, TX 47 60 43 53 38 / 5 10 20 10 20 DENTON, TX 49 72 45 53 39 / 0 5 10 5 20 MCKINNEY, TX 50 72 46 53 39 / 0 10 10 5 20 DALLAS, TX 55 73 50 55 43 / 0 5 10 5 20 TERRELL, TX 53 72 50 55 42 / 0 10 10 10 20 CORSICANA, TX 54 74 53 58 46 / 0 10 10 10 20 TEMPLE, TX 54 78 55 59 47 / 0 10 5 10 20 MINERAL WELLS, TX 50 68 44 56 39 / 0 5 5 0 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ /
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AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1022 PM CST WED JAN 23 2013 UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE .PREV DISCUSSION...ISSUED AT 745 PM CST WED JAN 23 2013... UPDATE...MUCH AS WITH THE INFLUX OF THE ARCTIC AIR SATURDAY EVENING...SHSN WOUND UP BEING MORE SIG THAN INITIALLY EXPECTED. BUT OTHER THAN THE LAKE-EFFECT AFFECTING N-C WI AND SOME LAKE- EFFECT PUSHING INTO THE NORTHERN DOOR...THE LAST SIG SHSN WAS EXITING THE FCST AREA OVER SRN LAKE WINNEBAGO. SKIES CLEARING RAPIDLY IN THE STG SUBSIDENCE BEHIND THE DEPARTING SHRTWV AND IN THE CAA REGIME AHEAD OF STG ANTICYCLONE HEADING INTO THE RGN. A FEW REPORTS OF SIG SNOWS RECEIVED FM THE DLH OFFICE FM IRON COUNTY WI. BUT FLOW ACRS LAKE SUPERIOR IS A BIT TOO NLY TO BE IDEAL FOR VILAS COUNTY...SO THINK REALLY SIG SNOWS WL REMAIN JUST W/NW OF VILAS. WIND CHILL SITN NOT REAL CLEAR CUT. A PERIOD OF GUSTY WINDS EXPECTED THIS EVENING AS COLD AIR RE-ASSERTS ITSELF ACRS THE AREA. BUT THEN LATER TNGT WINDS WL DIE OFF TO NEARLY CALM IN C/N-C WI AS SFC ANTICYCLONE NEARS THE RGN. IN THE END...MAY NOT HAVE A PROLONGED PERIOD OF WIND CHILLS REACHING ADVISORY CRITERIA. BUT IT WL BE CLOSE...SO NOT PLANNING ANY CHANGES TO THE HEADLINE AT THIS POINT. ACTUAL FCST MIN AIR TEMPS...HOWEVER...SEEMED A LITTLE WARM GIVEN STRENGTH OF CAA AND CURRENT TEMPS BACK OUT TO THE W. PLUS...SKIES ARE CLEARING AND SOME AREAS HAVE PROBABLY GOTTEN JUST ENOUGH SNOW FM THE SHSN THIS AFTN/EVE TO IMPACT TEMPS. EDGED MINS DOWN A LITTLE FM PREV FCST. UPDATED PRODUCT SUITE OUT ASAP. SKOWRONSKI DISCUSSION ISSUED AT 523 PM CST WED JAN 23 2013... SHORT TERM...TONIGHT AND THURSDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A COMPACT SHORTWAVE DIVING SOUTHEAST OVER THE ARROWHEAD OF MINNESOTA EARLY THIS AFTERNOON...WHICH IS HELPING TO PUSH ALONG A SURFACE LOW OVER SOUTHERN LAKE SUPERIOR. AHEAD OF THE SHORTWAVE...A COMBINATION OF DPVA AND ISENTROPIC ASCENT IS CONTRIBUTING TO OCCASIONAL LIGHT SNOW ACROSS MUCH OF THE STATE OF WISCONSIN. BEHIND THE SHORTWAVE...ANOTHER SURGE OF ARCTIC AIR IS SLIDING SOUTHEAST...WITH TEMPERATURES FALLING OVER NORTHERN MINNESOTA...AND WINDS GUSTING INTO THE 30-35 MPH RANGE. PLENTY OF CONCERNS IN THE SHORT TERM...INCLUDING LIGHT SNOW...WIND...AND WIND CHILL ISSUES. TONIGHT...THE SHORTWAVE TROUGH WILL BE OVERHEAD AT THE START OF THE EVENING BEFORE DEPARTING BY MIDNIGHT. SOME SNOW SHOWERS ARE DIURNALLY ENHANCED...BUT THINK WILL SEE SNOW SHOWERS LINGER EARLY THIS EVENING WITHIN THE LATEST REINFORCING SURGE OF ARCTIC AIR. BEHIND THE SHORTWAVE...LOW LEVEL WINDS WILL TURN TO THE NNW AND BECOME GUSTY FOR A PERIOD THIS EVENING. COULD SEE SOME GUSTS UP TO 30 MPH. THE WIND DIRECTION WILL ALSO INCREASE LAKE EFFECT POTENTIAL WITHIN THE SNOW BELTS OF N-C WISCONSIN. 850MB TEMPS IN THE MID 20S BELOW ZERO ARE NOT CONDUCIVE FOR GOOD ACCUMULATIONS (TALCUM POWDER SNOW)...BUT UP TO AN INCH OVER THE NW PART OF VILAS COUNTY LOOKS POSSIBLE. POTENTIAL WOULD BE THERE FOR MORE ACCUMS IF THE WIND DIRECTION DIDNT TURN DUE NORTH AFTER MIDNIGHT. ARCTIC HIGH PRESSURE WILL BE BUILDING SE INTO THE WESTERN GREAT LAKES AFTER MIDNIGHT AS WELL WHICH WILL CONTRIBUTE TO CLEARING SKIES. WINDS WILL BE DIMINISHING RATHER QUICKLY AND WILL LIKELY GO LIGHT AND VARIABLE LATE TONIGHT. THIS WILL SET UP CONCERNS FOR WIND CHILL HEADLINES. PROJECTED WIND CHILL VALUES FALL TO 20-25 BELOW BY 02Z OVER CENTRAL AND NORTH-CENTRAL WISCONSIN WHERE THEY WILL REMAIN UNTIL LATE TONIGHT WHEN WINDS DROP OFF. SO THIS SETS UP A WEIRD SCENARIO WHERE WIND CHILLS WILL BE THE COLDEST DURING THE LATE EVENING AND EARLY OVERNIGHT HOURS...BEFORE IMPROVING AS WINDS TURN CALM. WITH COORD FROM OTHER OFFICES...WILL RUN A WIND ADVISORY FROM 02Z THROUGH 12Z THU. POTENTIAL WILL BE THERE TO CANCEL EARLY IF WINDS DO TURN CALM. LOWS FROM 15 BELOW OVER NORTH-CENTRAL WISCONSIN TO AROUND 0 DEGREES NEAR LAKE MICHIGAN. THURSDAY...ARCTIC HIGH PRESSURE WILL BE CENTERED ACROSS THE REGION. ANY LINGERING LAKE EFFECT SNOW SHOWERS WILL BE ENDING THURSDAY MORNING AS WINDS TURN LIGHT AND BACK AROUND TO THE WEST. OTHERWISE WILL SEE A GOOD DEAL OF SUNSHINE. CIRRUS WILL BE INCREASING DURING THE AFTERNOON...BUT MORE SUNSHINE AND LOW LEVEL TEMPS SLIGHTLY WARMER THAN TODAY SHOULD GIVE TEMPS A DEGREE OR TWO WARMER IN MOST LOCATIONS. HIGHS FROM THE UPPER SINGLE DIGITS NORTH TO THE MID TEENS NEAR LAKE MICHIGAN. LONG TERM...THURSDAY NIGHT THROUGH TUESDAY. ALBERTA CLIPPER EXPECTED TO SWING ACROSS THE WESTERN LAKES THURSDAY NIGHT INTO FRIDAY. SNOW IS EXPECTED TO SPREAD INTO NORTHERN MINNESOTA THURSDAY AFTERNOON AND THEN OVERSPREAD THE FORECAST AREA THURSDAY NIGHT. STILL SOME DIFFERENCES WITH THE ONSET OF THE TIMING OF THE SNOW BETWEEN THE GFS/WRF...BUT TRENDED TOWARD THE QUICKER GFS/CANADIAN/ECMWF SOLUTION DUE TO COLD AIR MASS IN PLACE AND QUICKER SATURATION OF THE ATMOSPHERE. WENT WITH SNOW AFTER MIDNIGHT. ACCUMULATIONS SHOULD RANGE FROM 1 TO 3 INCHES ACROSS THE SOUTHWEST TO 2 TO 4 INCHES OVER NORTH-CENTRAL AND NORTHEAST WISCONSIN. WILL NEED TO WATCH DOOR COUNTY AS 925MB WINDS TURN TO THE SOUTH LATE THURSDAY NIGHT INTO FRIDAY MORNING. COULD SEE SOME LAKE EFFECT SNOW SHOWERS/LAKE ENHANCEMENT ACROSS NORTHERN DOOR COUNTY. LIGHT SNOW WILL CONTINUE INTO FRIDAY MORNING BEFORE TAPERING OFF TO SCATTERED SNOW SHOWERS OR FLURRIES FRIDAY AFTERNOON. AROUND AN INCH ADDITIONAL ACCUMULATION IS EXPECTED...BRINGING THE TOTAL STORM ACCUMULATIONS OF 2 TO 4 INCHES ACROSS THE SOUTHWEST PORTION OF THE FORECAST AREA WITH 3 TO 5 INCHES ELSEWHERE. LOCALLY HIGHER AMOUNTS ARE POSSIBLE ACROSS NORTHERN DOOR COUNTY DUE TO LAKE ENHANCEMENT/LAKE EFFECT POTENTIAL. COLDER AIR WILL WORK INTO THE REGION FRIDAY NIGHT. COULD BE SOME GUSTY WINDS BEHIND DEPARTING SYSTEM THAT COULD PRODUCE SOME BLOWING AND DRIFTING SNOW. WILL MENTION IN THE HAZARDOUS WEATHER OUTLOOK. ANOTHER SURGE OF ARCTIC AIR WILL PLUNGE INTO THE AREA BY SATURDAY MORNING WITH TEMPERATURES A FEW DEGREES BELOW ZERO ACROSS CENTRAL WISCONSIN AND NEAR 5 ABOVE ALONG THE LAKE. FORECAST CONFIDENCE WANES QUICKLY SUNDAY INTO THE MIDDLE OF NEXT WEEK. FIRST SYSTEM FOR SUNDAY INTO MONDAY. NEW ECMWF CONTINUES TO BRING BRUNT OF THE SYSTEM SOUTH OF THE AREA WITH ONLY PRECIPITATION UP TO HIGHWAY 29. THE GFS/CANADIAN WOULD SUPPORT AN ACCUMULATING SNOW SUNDAY INTO MONDAY. WILL CONTINUE WITH PREVIOUS FORECAST AS I SUSPECT THE ECMWF WILL SHIFT SYSTEM A LITTLE FURTHER NORTH. THE NEXT SYSTEM EARLY NEXT WEEK CONTINUES TO BE PROBLEMATIC AS WELL. THE CANADIAN/GFS DO NOT BRING SYSTEM UP ALONG THE ARCTIC BOUNDARY. THE 12Z ECMWF WOULD BRING A FAIRLY POTENT SYSTEM FOR MONDAY NIGHT INTO TUESDAY THAT WOULD BRING AN ONSET OF SNOW...FREEZING RAIN BEFORE CHANGING OVER TO RAIN OR FREEZING RAIN. DID NOT INTRODUCE FREEZING RAIN AT THIS TIME SINCE THERE WAS UNCERTAINTY IF THIS STORM WOULD ACTUALLY EXIST. OTHERWISE...ARCTIC AIR IS EXPECTED TO LINGER ALONG THE UNITED STATES/CANADIAN BORDER THROUGH THE END OF NEXT WEEK. HOW MUCH OF THIS ARCTIC INTRUSION WILL FILTER INTO NORTHEAST WISCONSIN IS STILL QUESTIONABLE...BUT IT APPEARS THAT BELOW NORMAL TEMPERATURES CAN BE EXPECTED THROUGH MUCH OF THE PERIOD...EXCEPT FOR THE POSSIBILITY OF TUESDAY IF ECMWF IS CORRECT. && .AVIATION...FOR 06Z TAF ISSUANCE. SUBSIDENCE HAS RESULTED IN RAPID CLEARING THIS EVENING. OTHER THAN SOME LINGERING SHSN NEAR THE UPPER MICHIGAN BORDER AND OVER FAR NRN DOOR COUNTY...VFR CONDITIONS EXPECTED THROUGH THU. SKOWRONSKI && .GRB WATCHES/WARNINGS/ADVISORIES... WIND CHILL ADVISORY UNTIL 6 AM CST THURSDAY FOR WIZ005-010-011- 018-019-030-035-036. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
936 AM CST THU JAN 24 2013 .DISCUSSION... 358 AM CST A LOT GOING ON THROUGH THE NEXT 7 DAYS... TODAY... LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z. HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF PRODUCING SOME ACCUMULATING SNOW. HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED. TONIGHT THROUGH FRIDAY... HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST. GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON. WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT 900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800 MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY NIGHT. SUNDAY THROUGH WEDNESDAY... HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55 RFD. MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH 850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT PERIOD OF SLEET/FREEZING RAIN. 00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN. THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID- LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY... THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF THROUGH THE DAY. FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY. WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING 500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * LAKE EFFECT SNOW SHOWERS THROUGH EARLY AFTERNOON...POSSIBLY DROPPING THE VIS UNDER 3 MILES AND DROPPING CIGS UNDER 2000 FT AT MDW AFTER 1645 UTC. * LIGHT SNOW EXPECTED ONCE AGAIN LATE TONIGHT AND EARLY FRIDAY MORNING WITH CEILINGS AND VIS FALLING TO MVFR. RODRIGUEZ/KB //DISCUSSION...UPDATED 16Z... A VERY IMPRESSIVE BAND OF LAKE EFFECT SNOW CONTINUES TO SLOWLY PROGRESS WEST SOUTHWESTWARD TOWARDS CHICAGO. THE MOST INTENSE BAND IS BASICALLY OFFSHORE FROM DOWNTOWN SOUTHWARD TO JUST WEST OF GARY. THE ACTIVITY WITHIN THIS BAND HAS BEEN VERY HEAVY WITH 1/4 OR LESS VIS. THIS BAND SHOULD BEGIN TO WEAKEN OVER THE NEXT HOUR OR TWO AS THE BOUNDARY LAYER FLOW BEGINS TO SHIFT MORE EAST SOUTHEASTWARD. HOWEVER...ENOUGH OF A CONVERGENCE ZONE LOOKS TO REMAIN IN PLACE TO CONTINUE TO SUPPORT LAKE EFFECT SNOW SHOWERS ACROSS THE AREA INTO THE EARLY TO MID AFTERNOON...BEFORE THE ACTIVITY RAPIDLY SHIFTS NORTHWARD. CURRENT TIMING WOULD BRING THE SNOW SHOWERS INTO MDW BY OR JUST PRIOR TO 17 UTC...WITH CONDITIONS LIKELY DROPPING BELOW 5 MILES ON -SNSH. I WILL CONTINUE TO MONITOR OVER THE NEXT 30 MINUTES TO SEE IF LOWER VIS IS JUSTIFIED AT MDW. CONDITIONS REMAIN MORE UNCERTAIN AT ORD AS THE SNOW SHOWERS MAY STRUGGLE TO GET TO FAR INLAND. HOWEVER...I STILL DO THINK THERE IS A DECENT POSSIBILITY THAT ORD WILL SEE SOME -SHSN AFTER 1730 UTC. //DISCUSSION...UPDATED 12Z... QUIET CONDITIONS TO START OFF THE FORECAST PERIOD HERE WITH ONLY HIGH LEVEL CIRRUS OVERHEAD. OF MAIN CONCERN THIS MORNING IS ONGOING LAKE EFFECT SNOW SHOWERS ACROSS NORTHWEST INDIANA...AS THIS SNOW IS EXPECTED TO DRIFT WESTWARD WITH TIME. AS THIS SNOW BAND SHIFTS WEST THIS MORNING IT WILL INITIALLY AFFECT GYY WITH MVFR CEILNGS OF AROUND 2500FT POSSIBLE...AS WELL AS A BRIEF PERIOD OF LIGHT SNOW BRINGING VIS OF 2-3SM. EXPECT THIS BAND TO REMAIN TRANSIENT QUICKLY MOVING WEST. THIS SNOW IS THEN EXPECTED TO MOVE ACROSS NORTHEAST ILLINOIS AFFECTING MDW/ORD BY MID MORNING. ALTHOUGH LIGHT SNOW IS POSSIBLE...IT DOES APPEAR THAT THE HEAVIER SNOW SHOWERS SHOULD STAY JUST TO THE EAST OF THE TERMINALS. NONETHELESS...IT COULD BRING A PERIOD OF MVFR CEILINGS AROUND 2500FT AND VIS TO REMAIN AT AROUND 3-5SM. ONCE AGAIN...THIS MOVING SNOW SHOULD CONTINUE TO PUSH NORTH INTO THE EARLY AFTERNOON WITH SNOW ENDING AS WELL AS OVERALL CONDITIONS IMPROVING. EXPECT ONLY MID LEVEL VFR CEILNGS LATE THIS AFTERNOON AND MOST OF THIS EVENING AS THE NEXT SYSTEM APPROACHES. CEILINGS WILL FALL ONCE AGAIN LATE TONIGHT INTO EARLY FRIDAY MORNING AS LIGHT SNOW/LOWER VIS OVERSPREADS THE TERMINALS AND CONTINUES THROUGH THE REMAINDER OF THE FORECAST PERIOD. RODRIGUEZ //ORD AND MDW CONFIDENCE...UPDATED 16Z... * MEDIUM TO HIGH CONFIDENCE WITH LIGHT SNOW/MVFR VIS/MVFR CEILINGS AT MDW LATER THIS MORNING. LOWER CONFIDENCE AT ORD. * MEDIUM CONFIDENCE WITH LIGHT SNOW AGAIN LATE TONIGHT AND EARLY FRIDAY MORNING. RODRIGUEZ/KB //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...VFR. SATURDAY...VFR. SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS LIKELY. MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH FREEZING RAIN EARLY. MVFR/IFR CONDITIONS LIKELY. TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE. WEDNESDAY...CHANCE LIGHT SNOW SHOWERS. MVFR CONDITIONS POSSIBLE. RODRIGUEZ && .MARINE... 439 AM CST AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO 35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS. EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30 KT WINDS EXPECTED TO PERSIST INTO SATURDAY. RODRIGUEZ && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...LAKE EFFECT SNOW ADVISORY...INZ001 UNTIL NOON THURSDAY. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 PM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
603 AM CST THU JAN 24 2013 .DISCUSSION... 358 AM CST A LOT GOING ON THROUGH THE NEXT 7 DAYS... TODAY... LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z. HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF PRODUCING SOME ACCUMULATING SNOW. HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED. TONIGHT THROUGH FRIDAY... HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST. GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON. WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT 900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800 MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY NIGHT. SUNDAY THROUGH WEDNESDAY... HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55 RFD. MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH 850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT PERIOD OF SLEET/FREEZING RAIN. 00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN. THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID- LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY... THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF THROUGH THE DAY. FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY. WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING 500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * NORTHWEST WINDS WITH SPORADIC GUSTS TO THE MID TEENS THIS MORNING...THEN VEERING TO THE NORTHEAST AND THEN SOUTHEAST TODAY. * POSSIBILITY FOR LIGHT SNOW/MVFR VIS/MVFR CEILINGS BY MID MORNING TODAY...AND PERSISTING INTO THE EARLY AFTERNOON. * LIGHT SNOW EXPECTED ONCE AGAIN LATE TONIGHT AND EARLY FRIDAY MORNING WITH CEILINGS AND VIS FALLING TO MVFR. RODRIGUEZ //DISCUSSION...UPDATED 12Z... QUIET CONDITIONS TO START OFF THE FORECAST PERIOD HERE WITH ONLY HIGH LEVEL CIRRUS OVERHEAD. OF MAIN CONCERN THIS MORNING IS ONGOING LAKE EFFECT SNOW SHOWERS ACROSS NORTHWEST INDIANA...AS THIS SNOW IS EXPECTED TO DRIFT WESTWARD WITH TIME. AS THIS SNOW BAND SHIFTS WEST THIS MORNING IT WILL INITIALLY AFFECT GYY WITH MVFR CEILNGS OF AROUND 2500FT POSSIBLE...AS WELL AS A BRIEF PERIOD OF LIGHT SNOW BRINGING VIS OF 2-3SM. EXPECT THIS BAND TO REMAIN TRANSIENT QUICKLY MOVING WEST. THIS SNOW IS THEN EXPECTED TO MOVE ACROSS NORTHEAST ILLINOIS AFFECTING MDW/ORD BY MID MORNING. ALTHOUGH LIGHT SNOW IS POSSIBLE...IT DOES APPEAR THAT THE HEAVIER SNOW SHOWERS SHOULD STAY JUST TO THE EAST OF THE TERMINALS. NONETHELESS...IT COULD BRING A PERIOD OF MVFR CEILINGS AROUND 2500FT AND VIS TO REMAIN AT AROUND 3-5SM. ONCE AGAIN...THIS MOVING SNOW SHOULD CONTINUE TO PUSH NORTH INTO THE EARLY AFTERNOON WITH SNOW ENDING AS WELL AS OVERALL CONDITIONS IMPROVING. EXPECT ONLY MID LEVEL VFR CEILNGS LATE THIS AFTERNOON AND MOST OF THIS EVENING AS THE NEXT SYSTEM APPROACHES. CEILINGS WILL FALL ONCE AGAIN LATE TONIGHT INTO EARLY FRIDAY MORNING AS LIGHT SNOW/LOWER VIS OVERSPREADS THE TERMINALS AND CONTINUES THROUGH THE REMAINDER OF THE FORECAST PERIOD. RODRIGUEZ //ORD AND MDW CONFIDENCE...UPDATED 12Z... * MEDIUM HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION TODAY. * MEDIUM CONFIDENCE WITH LIGHT SNOW/MVFR VIS/MVFR CEILINGS TRENDS BY MID MORNING. * MEDIUM CONFIDENCE WITH LIGHT SNOW AGAIN LATE TONIGHT AND EARLY FRIDAY MORNING. RODRIGUEZ //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...VFR. SATURDAY...VFR. SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS LIKELY. MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH FREEZING RAIN EARLY. MVFR/IFR CONDITIONS LIKELY. TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE. WEDNESDAY...CHANCE LIGHT SNOW SHOWERS. MVFR CONDITIONS POSSIBLE. RODRIGUEZ && .MARINE... 439 AM CST AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO 35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS. EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30 KT WINDS EXPECTED TO PERSIST INTO SATURDAY. RODRIGUEZ && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...LAKE EFFECT SNOW ADVISORY...INZ001-INZ002 UNTIL NOON THURSDAY. LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 AM THURSDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM THURSDAY. GALE WARNING...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 10 AM THURSDAY. SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM THURSDAY TO 4 PM THURSDAY. && $$
AREA FORECAST DISCUSSION...CORRECTED
NWS CHICAGO/ROMEOVILLE IL
522 AM CST THU JAN 24 2013 .DISCUSSION... 358 AM CST A LOT GOING ON THROUGH THE NEXT 7 DAYS... TODAY... LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z. HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF PRODUCING SOME ACCUMULATING SNOW. HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED. TONIGHT THROUGH FRIDAY... HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST. GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON. WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT 900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800 MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY NIGHT. SUNDAY THROUGH WEDNESDAY... HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55 RFD. MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH 850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT PERIOD OF SLEET/FREEZING RAIN. 00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN. THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID- LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY... THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF THROUGH THE DAY. FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY. WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING 500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * NORTHWEST WINDS GUSTING TO THE MID TEENS EARLY THIS MORNING...THEN VEERING TO THE NORTHEAST AND THEN SOUTHEAST TODAY. * POSSIBILITY FOR LIGHT SNOW/MVFR VIS/MVFR CEILINGS BY MID MORNING TODAY...AND PERSISTING INTO THE EARLY AFTERNOON. * POSSIBILITY FOR LIGHT SNOW AGAIN LATE IN THE PERIOD...EARLY FRIDAY MORNING. RODRIGUEZ //DISCUSSION...UPDATED 06Z... MAIN CONCERNS TODAY WILL BE CENTERED AROUND ONGOING LAKE EFFECT SNOW SHOWERS CURRENTLY PUSHING SOUTH THROUGH NORTHWEST INDIANA. EXPECT THESE SNOW SHOWERS TO PERSIST THIS MORNING INITIALLY AFFECTING GYY IN THE NEAR TERM...WITH VIS DROPPING BELOW 1 MILE AT TIMES. THIS SHOULD AFFECT GYY THROUGH AROUND THE 12Z TIME...WITH THIS SNOW THEN SHIFTING MORE TOWARDS NORTHEAST ILLINOIS. ALTHOUGH THIS SNOW WILL MOVE TOWARDS THE MDW/ORD TERMINALS...EXPECT A SLIGHT DIMINISHING TREND BUT OF MORE IMPORTANCE EXPECT THE MAIN SNOW BAND TO REMAIN JUST EAST OF THE TERMINALS. DESPITE THIS...DO EXPECT VIS OF 3-5SM IN LIGHT SNOW TO BE POSSIBLE FOR ORD/MDW THROUGH MID TO LATE MORNING BEFORE IT CONTINUES TO SHIFT NORTHEAST OUT OF THE AREA. RODRIGUEZ //ORD AND MDW CONFIDENCE...UPDATED 09Z... * HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION. * MEDIUM CONFIDENCE WITH LIGHT SNOW/MVFR VIS/MVFR CEILINGS TRENDS BY MID MORNING. * MEDIUM CONFIDENCE WITH LIGHT SNOW AGAIN LATE IN THE PERIOD. RODRIGUEZ //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...SNOW LIKELY...MAINLY IN THE MORNING...WITH IFR CONDITIONS AND LIGHT SNOW POSSIBLY LINGERING THROUGH THE AFTERNOON. CONDITIONS SHOULD IMPROVE TO VFR IN THE EVENING. SATURDAY...VFR. WX NIL. SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS LIKELY. MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH FREEZING RAIN EARLY...AND POSSIBLY MIXING WITH SNOW OVERNIGHT. MVFR/IFR CONDITIONS LIKELY. TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE. KREIN && .MARINE... 439 AM CST AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO 35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS. EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30 KT WINDS EXPECTED TO PERSIST INTO SATURDAY. RODRIGUEZ && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...LAKE EFFECT SNOW ADVISORY...INZ001-INZ002 UNTIL NOON THURSDAY. LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 AM THURSDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM THURSDAY. GALE WARNING...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 10 AM THURSDAY. SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM THURSDAY TO 4 PM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
439 AM CST THU JAN 24 2013 .DISCUSSION... 358 AM CST - - DDHHMM WRKMAR A LOT GOING ON THROUGH THE NEXT 7 DAYS... TODAY... LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z. HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF PRODUCING SOME ACCUMULATING SNOW. HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED. TONIGHT THROUGH FRIDAY... HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST. GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON. WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT 900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800 MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY NIGHT. SUNDAY THROUGH WEDNESDAY... HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55 RFD. MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH 850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT PERIOD OF SLEET/FREEZING RAIN. 00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN. THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID- LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY... THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF THROUGH THE DAY. FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY. WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING 500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * NORTHWEST WINDS GUSTING TO THE MID TEENS EARLY THIS MORNING...THEN VEERING TO THE NORTHEAST AND THEN SOUTHEAST TODAY. * POSSIBILITY FOR LIGHT SNOW/MVFR VIS/MVFR CEILINGS BY MID MORNING TODAY...AND PERSISTING INTO THE EARLY AFTERNOON. * POSSIBILITY FOR LIGHT SNOW AGAIN LATE IN THE PERIOD...EARLY FRIDAY MORNING. RODRIGUEZ //DISCUSSION...UPDATED 06Z... MAIN CONCERNS TODAY WILL BE CENTERED AROUND ONGOING LAKE EFFECT SNOW SHOWERS CURRENTLY PUSHING SOUTH THROUGH NORTHWEST INDIANA. EXPECT THESE SNOW SHOWERS TO PERSIST THIS MORNING INITIALLY AFFECTING GYY IN THE NEAR TERM...WITH VIS DROPPING BELOW 1 MILE AT TIMES. THIS SHOULD AFFECT GYY THROUGH AROUND THE 12Z TIME...WITH THIS SNOW THEN SHIFTING MORE TOWARDS NORTHEAST ILLINOIS. ALTHOUGH THIS SNOW WILL MOVE TOWARDS THE MDW/ORD TERMINALS...EXPECT A SLIGHT DIMINISHING TREND BUT OF MORE IMPORTANCE EXPECT THE MAIN SNOW BAND TO REMAIN JUST EAST OF THE TERMINALS. DESPITE THIS...DO EXPECT VIS OF 3-5SM IN LIGHT SNOW TO BE POSSIBLE FOR ORD/MDW THROUGH MID TO LATE MORNING BEFORE IT CONTINUES TO SHIFT NORTHEAST OUT OF THE AREA. RODRIGUEZ //ORD AND MDW CONFIDENCE...UPDATED 09Z... * HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION. * MEDIUM CONFIDENCE WITH LIGHT SNOW/MVFR VIS/MVFR CEILINGS TRENDS BY MID MORNING. * MEDIUM CONFIDENCE WITH LIGHT SNOW AGAIN LATE IN THE PERIOD. RODRIGUEZ //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...SNOW LIKELY...MAINLY IN THE MORNING...WITH IFR CONDITIONS AND LIGHT SNOW POSSIBLY LINGERING THROUGH THE AFTERNOON. CONDITIONS SHOULD IMPROVE TO VFR IN THE EVENING. SATURDAY...VFR. WX NIL. SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS LIKELY. MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH FREEZING RAIN EARLY...AND POSSIBLY MIXING WITH SNOW OVERNIGHT. MVFR/IFR CONDITIONS LIKELY. TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE. KREIN && .MARINE... 439 AM CST AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO 35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS. EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30 KT WINDS EXPECTED TO PERSIST INTO SATURDAY. RODRIGUEZ && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...LAKE EFFECT SNOW ADVISORY...INZ001-INZ002 UNTIL NOON THURSDAY. LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 AM THURSDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM THURSDAY. GALE WARNING...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 10 AM THURSDAY. SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM THURSDAY TO 4 PM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
920 AM EST THU JAN 24 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 338 AM EST THU JAN 24 2013 HIGH PRESSURE WILL BRING DRY CHILLY WEATHER TO CENTRAL INDIANA TODAY. LOW PRESSURE WILL TRACK THROUGH THE GREAT LAKES ON FRIDAY...WITH SNOW DEVELOPING LATE TONIGHT AND CONTINUING THROUGH FRIDAY AFTERNOON. A MORE ACTIVE WEATHER PATTERN ARRIVES BEGINNING SUNDAY AND CONTINUING INTO NEXT WEEK AS A WARM FRONT LIFTS INTO THE REGION WITH SEVERAL DISTURBANCES TRACKING ALONG IT. AFTER THE POTENTIAL FOR A WINTRY MIX SUNDAY AFTERNOON AND NIGHT...TEMPERATURES WILL BE WARM ENOUGH FOR RAIN FOR MUCH OF NEXT WEEK. && .NEAR TERM /TODAY/... ISSUED AT 338 AM EST THU JAN 24 2013 LAKE EFFECT SNOW SHOWERS AND FLURRIES CONTINUE TO MOVE SOUTH INTO THE NORTHERN HALF OF THE FORECAST AREA EARLY THIS MORNING. OUTSIDE OF SNOW SHOWERS/FLURRIES...SKIES WERE PARTLY CLOUDY AS HIGH PRESSURE BEGINNING TO EXPAND INTO THE REGION. TEMPS WERE FALLING THROUGH THE 20S AND INTO THE TEENS AS COLD ADVECTION ESTABLISHES. INITIAL FOCUS OF THE NEAR TERM IS ON THE TRANSIENT NATURE OF THE SNOW SHOWERS AND FLURRIES COMING OUT OF NORTHERN INDIANA AND INTO NORTHERN COUNTIES. LOW LEVEL FLOW VIA THE MOST RECENT RAP DATA REMAINS FROM THE NORTHWEST WITH THE VAD PROFILE OFF OF THE KIND RADAR INDICATING 25-30KTS PRESENT AT ABOUT 3KFT. HAVE SEEN POCKETS OF HEAVIER SNOW SHOWERS WITHIN A BAND EXTENDING FROM LOGANSPORT SOUTHEAST THROUGH KOKOMO TO NEAR NOBLESVILLE. EXPECT THESE SNOW SHOWERS/FLURRIES TO SHIFT WEST AND WEAKEN AS THEY DROP SOUTH WITH BOUNDARY LAYER FLOW SET TO VEER TO A MORE NORTHERLY DIRECTION THROUGH DAYBREAK. THERE ARE SIGNS THIS SHIFT IN LOW LEVEL FLOW IS ALREADY BEGINNING AS AN INCREASINGLY DOMINANT SNOW BAND DEVELOPING DUE SOUTH OFF OF LAKE MICHIGAN OVER LAKE AND PORTER COS. POTENTIAL REMAINS FOR THE OUTER FRINGES OF THIS BAND TO WORK ALL THE WAY SOUTH INTO CARROLL AND TIPPECANOE COS AFTER 09Z AND THROUGH DAYBREAK BEFORE LOW LEVEL FLOW VEERS FURTHER AND WEAKENS. HAVE HELD ONTO LOW CHANCE POPS FOR THE NEXT FEW HOURS TO ACCOUNT FOR ONGOING SNOW SHOWERS...THEN REFOCUSED IT OVER THE NORTHERN WABASH VALLEY TO ENCOMPASS ABOVE THOUGHTS. COULD SEE A DUSTING IN LOCALIZED AREAS OVER THE NEXT FEW HOURS TO THE NORTH OF INDY...BUT WITH A DRY SNOW MOST WILL BE BLOWN AROUND MORE THAN ANYTHING ELSE. BROAD CANADIAN HIGH PRESSURE WILL THEN TAKE OVER FOR THE REMAINDER OF THE SHORT TERM...WITH ANOTHER SURGE OF DRY ARCTIC AIR SPREADING ACROSS THE REGION. DEEP SUBSIDENCE EXPANDING INTO THE BOUNDARY LAYER WILL LEAD TO MOSTLY SUNNY SKIES THROUGH MIDDAY...WITH A SLOW EXPANSION IN MID AND HIGH LEVEL CLOUDS BY LATE AFTERNOON AS MOISTURE ALOFT SPREADS INTO THE REGION FROM THE NORTHWEST. WIND GUSTS THIS MORNING SHOULD DROP OFF RATHER QUICKLY AS THE CENTER OF THE HIGH MOVES ACROSS THE REGION THIS AFTERNOON. TEMPS...COLD ADVECTION THROUGH THE AFTERNOON WILL KEEP IT CHILLY... WITH LOW LEVEL THERMALS SUPPORTING MOS TEMPS IN THE LOWER TO MID 20S. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... ISSUED AT 338 AM EST THU JAN 24 2013 FORECAST CHALLENGES FOCUS ON SNOW CHANCES LATE TONIGHT THROUGH FRIDAY AS LOW PRESSURE DROPS THROUGH THE GREAT LAKES. STILL SOME DISCREPANCIES BETWEEN MODELS WITH RESPECT TO MOISTURE AVAILABILITY AND FORCING ASSOCIATED WITH THE SURFACE WAVE...BUT OVERALL GUIDANCE IN BETTER AGREEMENT THIS MORNING ON THE MAIN FEATURES. CLOUDS WILL INCREASE TONIGHT AS THE WAVE APPROACHES FROM THE NORTHWEST AS ISENTROPIC LIFT AND MOISTURE DEVELOP ALONG A BOUNDARY OVER THE TENNESSEE VALLEY. SUSPECT MOISTENING OF THE LOWER LEVELS WILL TAKE SOME TIME AND EFFORT AFTER MIDNIGHT AS SURFACE FLOW DIRECTION VEERS ONLY SLOWLY FROM EASTERLY TO A MORE S/SE DIRECTION BY 12Z FRIDAY. HAVE DELAYED ONSET OF POPS UNTIL LATE TONIGHT WITH THE INITIAL VERY DRY BOUNDARY LAYER. STILL HAVE QUESTIONS AS TO THE DEPTH OF THE MOISTURE THAT WILL ACCOMPANY THE SYSTEM...AS NO STRONG GULF FEED WILL BE PRESENT WITH BOUNDARY LAYER WINDS SHIFTING MORE TO A W/SW FLOW. BRIEF PERIOD OF ISENTROPIC LIFT DEVELOPS JUST PRIOR TO DAYBREAK AND EXTENDS THROUGH THE MORNING FRIDAY BEFORE MOISTURE AND MORE SUBSTANTIAL LIFT SHIFTS EAST INTO THE AFTERNOON. MODEL SOUNDINGS CONTINUE TO SHOW PRECIP FALLING AS ALL SNOW ACROSS THE FORECAST AREA...ALTHOUGH HINTS OF A THIN LAYER OF ABOVE FREEZING AIR IN THE BOUNDARY LAYER BRIEFLY COMING INTO SOUTHERN INDIANA FRIDAY MORNING HAVE RETURNED. FOCUS OF HEAVIEST SNOWFALL FRIDAY MORNING SHOULD SET UP OVER THE NORTHEAST HALF OF THE FORECAST AREA WHERE AXIS OF STRONGEST ISENTROPIC LIFT COMBINES WITH A PERIOD WITH GREATER VERTICAL VELOCITIES AND A SLIGHTLY DEEPER DENDRITIC GROWTH ZONE. WITH SNOW RATIOS LIKELY TO BE ELEVATED AND CLOSER TO 15 TO 1 IN THESE AREAS...FEEL COMFORTABLE PLACING A GENERAL 1 TO 2 INCHES THROUGH FRIDAY AFTERNOON NORTHEAST OF A ROCKVILLE-MARTINSVILLE- COLUMBUS LINE WITH AMOUNTS DROPPING OFF QUICKLY TO THE SOUTH OF THAT LINE. OP GFS EVEN HINTS AT DEVELOPMENT OF A TROWAL OVER OHIO FRIDAY MORNING WHICH MAY SERVE TO ENHANCE LIFT EVEN A TOUCH MORE OVER NORTHEAST COUNTIES AND ENABLE A FEW SPOTS FROM KOKOMO TO MUNCIE AND WINCHESTER TO MAKE A RUN AT 2 TO 3 INCHES FOR A FINAL TALLY. DRIER AIR WILL ADVECT INTO THE REGION FROM THE WEST RATHER QUICKLY ON FRIDAY AFTERNOON...SHUTTING OFF LIGHT SNOW FOR MOST OF THE REGION AND POTENTIALLY EVEN LEADING TO SOME CLEARING LATE. HAVE HELD ONTO LOW CHANCE POPS HOWEVER THROUGH THE REST OF THE AFTERNOON OVER NORTHEAST HALF OF THE FORECAST AREA AS A SECONDARY WAVE ALOFT DROPS THROUGH THE LOWER GREAT LAKES WITH THE SURFACE LOW AND MAY SERVE TO MAINTAIN SCATTERED LIGHT SNOW SHOWERS OR FLURRIES. ANY LINGERING FLURRIES WILL END OVER NORTHEAST COUNTIES FRIDAY EVENING WITH HIGH PRESSURE REESTABLISHING OVER THE REGION FOR THE REMAINDER OF THE SHORT TERM. THE HIGH WILL BRING ANOTHER SHOT OF COLDER AIR FOR FRIDAY NIGHT AND SATURDAY...BUT WARM ADVECTION WILL COMMENCE SATURDAY NIGHT AS THE HIGH MOVES OFF TO THE EAST AND RIDGING ALOFT EXPANDS INTO THE OHIO VALLEY. MID AND HIGH LEVEL CLOUD COVER WILL INCREASE LATE SATURDAY NIGHT AS LOW PRESSURE AND AN ASSOCIATED WARM FRONT LIFTS OUT OF THE CENTRAL PLAINS. TEMPS...PREFERRED COOLER METMOS GUIDANCE FOR HIGHS FRIDAY AS CLOUDS AND PRECIP FOR MUCH OF THE DAY FOLLOWED BY COLD ADVECTION. MAVMOS LOOKED REASONABLE FOR HIGHS SATURDAY PRIMARILY IN THE MID AND UPPER 20S. TRENDED TOWARDS MAVMOS FOR LOWS TONIGHT...THEN GENERALLY WENT AT OR A COUPLE DEGREES BELOW GUIDANCE FOR FRI/SAT NIGHTS CONSIDERING MAY HAVE A THIN SNOW COVER IN SOME SPOTS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... ISSUED AT 327 AM EST THU JAN 24 2013 AN ACTIVE WEATHER PATTERN SETS UP IN THE LONG TERM WITH AN UPPER TROUGH MOVING THROUGH THE PACIFIC NORTHWEST INTO THE CENTRAL U.S. THROUGH THE PERIOD. A SERIES OF UPPER SHORTWAVES WILL EJECT FROM THE UPPER TROUGH AND BRING CHANCES FOR PRECIPITATION TO THE AREA. AT THE SURFACE A WARM FRONT WILL FORM SOUTH OF THE AREA AND SLOWLY MOVE NORTH BEFORE THE SURFACE LOW EJECTS FROM THE PLAINS AND TRAVERSES THE GREAT LAKES. MODELS HAVE SOME MINOR DISAGREEMENTS IN TIMING/TEMPERATURES EARLY WITH SIGNIFICANT DIFFERENCES BY TUESDAY NIGHT. GENERALLY ACCEPTED ALLBLEND INITIALIZATION. BIGGEST CHALLENGE WILL BE PRECIPITATION TYPE FOR SUNDAY-MONDAY. ENTIRE COLUMN IS BELOW FREEZING SUNDAY MORNING BEFORE PRECIPITATION ARRIVES. BY SUNDAY AFTERNOON WITH UPPER SHORTWAVE APPROACHING ECMWF AND GFS SHOW AN INTRUSION OF WARM AIR ALOFT INTO THE SOUTHWEST AND BY SUNDAY NIGHT THIS MOVES ALL ACROSS THE AREA. MOST OF THE AREA SHOULD SEE A PROGRESSION FROM A CHANCE FOR SNOW TO A CHANCE FOR SNOW AND SLEET TO A CHANCE FOR FREEZING RAIN AND SLEET BEFORE TRANSITIONING TO RAIN. TRIED TO MATCH TRANSITION UP WITH FORECAST SOUNDINGS AND PARTIAL THICKNESSES...BUT BOTTOM LINE IS MUCH OF THE AREA WILL SEE SOME TYPE OF WINTRY MIX BEFORE THE TRANSITION TO ALL RAIN WHICH SHOULD OCCUR BY SOMETIME MONDAY MORNING. THEN CHANCES FOR RAIN WILL BE THE RULE UNTIL WEDNESDAY WHEN PRECIP TYPE IS UP IN THE AIR BECAUSE OF AFOREMENTIONED SIGNIFICANT MODEL TEMPERATURE DIFFERENCES. ANOTHER ITEM OF NOTE IS THE STRENGTH OF THE SYSTEM EJECTING FROM THE PLAINS TUESDAY/TUESDAY NIGHT. IF THE VERY WARM GFS WERE TO VERIFY COULD SEE CHANCES FOR THUNDER EEK THIS FAR NORTH. WILL LEAVE OUT FOR NOW AS ECMWF PAINTS A MUCH DIFFERENT PICTURE AND WOULD RATHER HAVE SOME AGREEMENT TO INCLUDE THUNDER THIS TIME OF YEAR. && .AVIATION /DISCUSSION FOR 241500Z IND TAF UPDATE/... ISSUED AT 920 AM EST THU JAN 24 2013 OBSERVATIONAL...SATELLITE AND RADAR TRENDS ALONG WITH MODEL TIME SECTIONS SUGGEST THERE WILL BE LITTLE TO NO CU THE REST OF THE DAY WITH ONLY THICK CIRRUS LEFT BEHIND. SO...PULLED SCATTERED CU...OTHERWISE...TAF LOOKS GOOD. PREVIOUS DISCUSSION FOLLOWS... MAINLY VFR CONDITIONS AT THE SITES THROUGH THE PERIOD. THE ONLY EXCEPTION TO THIS COULD BE OVER THE NEXT COUPLE OF HOURS WITH LAKE EFFECT SNOW SHOWERS CONTINUING TO DRIFT SOUTH. THESE LEFTOVER ECHOES COULD BRIEFLY DROP KIND AND KBMG TO MVFR BUT DO NOT EXPECT THIS TO LAST FOR LONG. COULD ACTUALLY BE FINISHED ISSUANCE TIME AT KIND BUT MAY INCLUDE A BRIEF MENTION AT KBMG FOR MVFR CEILINGS. AFTER THAT ONLY SOME CIRRUS EXPECTED THROUGH THE DAY. A CLIPPER SYSTEM WILL APPROACH NEAR THE END OF THE PERIOD AND BRING LOWERING CEILINGS...BUT DON/T EXPECT AN IMPACT ON FLYING CONDITIONS UNTIL THE EXTENDED PORTION OF THE TAF. WINDS WILL SHIFT FROM NORTHWEST TO NORTHEAST LATER THIS MORNING BEFORE BECOMING SOUTHEASTERLY THIS EVENING. SPEED GENERALLY 5 TO 12 KTS WITH NO GUSTS EXPECTED. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM....CP AVIATION...CP/MK
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
550 AM EST THU JAN 24 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 338 AM EST THU JAN 24 2013 HIGH PRESSURE WILL BRING DRY CHILLY WEATHER TO CENTRAL INDIANA TODAY. LOW PRESSURE WILL TRACK THROUGH THE GREAT LAKES ON FRIDAY...WITH SNOW DEVELOPING LATE TONIGHT AND CONTINUING THROUGH FRIDAY AFTERNOON. A MORE ACTIVE WEATHER PATTERN ARRIVES BEGINNING SUNDAY AND CONTINUING INTO NEXT WEEK AS A WARM FRONT LIFTS INTO THE REGION WITH SEVERAL DISTURBANCES TRACKING ALONG IT. AFTER THE POTENTIAL FOR A WINTRY MIX SUNDAY AFTERNOON AND NIGHT...TEMPERATURES WILL BE WARM ENOUGH FOR RAIN FOR MUCH OF NEXT WEEK. && .NEAR TERM /TODAY/... ISSUED AT 338 AM EST THU JAN 24 2013 LAKE EFFECT SNOW SHOWERS AND FLURRIES CONTINUE TO MOVE SOUTH INTO THE NORTHERN HALF OF THE FORECAST AREA EARLY THIS MORNING. OUTSIDE OF SNOW SHOWERS/FLURRIES...SKIES WERE PARTLY CLOUDY AS HIGH PRESSURE BEGINNING TO EXPAND INTO THE REGION. TEMPS WERE FALLING THROUGH THE 20S AND INTO THE TEENS AS COLD ADVECTION ESTABLISHES. INITIAL FOCUS OF THE NEAR TERM IS ON THE TRANSIENT NATURE OF THE SNOW SHOWERS AND FLURRIES COMING OUT OF NORTHERN INDIANA AND INTO NORTHERN COUNTIES. LOW LEVEL FLOW VIA THE MOST RECENT RAP DATA REMAINS FROM THE NORTHWEST WITH THE VAD PROFILE OFF OF THE KIND RADAR INDICATING 25-30KTS PRESENT AT ABOUT 3KFT. HAVE SEEN POCKETS OF HEAVIER SNOW SHOWERS WITHIN A BAND EXTENDING FROM LOGANSPORT SOUTHEAST THROUGH KOKOMO TO NEAR NOBLESVILLE. EXPECT THESE SNOW SHOWERS/FLURRIES TO SHIFT WEST AND WEAKEN AS THEY DROP SOUTH WITH BOUNDARY LAYER FLOW SET TO VEER TO A MORE NORTHERLY DIRECTION THROUGH DAYBREAK. THERE ARE SIGNS THIS SHIFT IN LOW LEVEL FLOW IS ALREADY BEGINNING AS AN INCREASINGLY DOMINANT SNOW BAND DEVELOPING DUE SOUTH OFF OF LAKE MICHIGAN OVER LAKE AND PORTER COS. POTENTIAL REMAINS FOR THE OUTER FRINGES OF THIS BAND TO WORK ALL THE WAY SOUTH INTO CARROLL AND TIPPECANOE COS AFTER 09Z AND THROUGH DAYBREAK BEFORE LOW LEVEL FLOW VEERS FURTHER AND WEAKENS. HAVE HELD ONTO LOW CHANCE POPS FOR THE NEXT FEW HOURS TO ACCOUNT FOR ONGOING SNOW SHOWERS...THEN REFOCUSED IT OVER THE NORTHERN WABASH VALLEY TO ENCOMPASS ABOVE THOUGHTS. COULD SEE A DUSTING IN LOCALIZED AREAS OVER THE NEXT FEW HOURS TO THE NORTH OF INDY...BUT WITH A DRY SNOW MOST WILL BE BLOWN AROUND MORE THAN ANYTHING ELSE. BROAD CANADIAN HIGH PRESSURE WILL THEN TAKE OVER FOR THE REMAINDER OF THE SHORT TERM...WITH ANOTHER SURGE OF DRY ARCTIC AIR SPREADING ACROSS THE REGION. DEEP SUBSIDENCE EXPANDING INTO THE BOUNDARY LAYER WILL LEAD TO MOSTLY SUNNY SKIES THROUGH MIDDAY...WITH A SLOW EXPANSION IN MID AND HIGH LEVEL CLOUDS BY LATE AFTERNOON AS MOISTURE ALOFT SPREADS INTO THE REGION FROM THE NORTHWEST. WIND GUSTS THIS MORNING SHOULD DROP OFF RATHER QUICKLY AS THE CENTER OF THE HIGH MOVES ACROSS THE REGION THIS AFTERNOON. TEMPS...COLD ADVECTION THROUGH THE AFTERNOON WILL KEEP IT CHILLY... WITH LOW LEVEL THERMALS SUPPORTING MOS TEMPS IN THE LOWER TO MID 20S. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... ISSUED AT 338 AM EST THU JAN 24 2013 FORECAST CHALLENGES FOCUS ON SNOW CHANCES LATE TONIGHT THROUGH FRIDAY AS LOW PRESSURE DROPS THROUGH THE GREAT LAKES. STILL SOME DISCREPANCIES BETWEEN MODELS WITH RESPECT TO MOISTURE AVAILABILITY AND FORCING ASSOCIATED WITH THE SURFACE WAVE...BUT OVERALL GUIDANCE IN BETTER AGREEMENT THIS MORNING ON THE MAIN FEATURES. CLOUDS WILL INCREASE TONIGHT AS THE WAVE APPROACHES FROM THE NORTHWEST AS ISENTROPIC LIFT AND MOISTURE DEVELOP ALONG A BOUNDARY OVER THE TENNESSEE VALLEY. SUSPECT MOISTENING OF THE LOWER LEVELS WILL TAKE SOME TIME AND EFFORT AFTER MIDNIGHT AS SURFACE FLOW DIRECTION VEERS ONLY SLOWLY FROM EASTERLY TO A MORE S/SE DIRECTION BY 12Z FRIDAY. HAVE DELAYED ONSET OF POPS UNTIL LATE TONIGHT WITH THE INITIAL VERY DRY BOUNDARY LAYER. STILL HAVE QUESTIONS AS TO THE DEPTH OF THE MOISTURE THAT WILL ACCOMPANY THE SYSTEM...AS NO STRONG GULF FEED WILL BE PRESENT WITH BOUNDARY LAYER WINDS SHIFTING MORE TO A W/SW FLOW. BRIEF PERIOD OF ISENTROPIC LIFT DEVELOPS JUST PRIOR TO DAYBREAK AND EXTENDS THROUGH THE MORNING FRIDAY BEFORE MOISTURE AND MORE SUBSTANTIAL LIFT SHIFTS EAST INTO THE AFTERNOON. MODEL SOUNDINGS CONTINUE TO SHOW PRECIP FALLING AS ALL SNOW ACROSS THE FORECAST AREA...ALTHOUGH HINTS OF A THIN LAYER OF ABOVE FREEZING AIR IN THE BOUNDARY LAYER BRIEFLY COMING INTO SOUTHERN INDIANA FRIDAY MORNING HAVE RETURNED. FOCUS OF HEAVIEST SNOWFALL FRIDAY MORNING SHOULD SET UP OVER THE NORTHEAST HALF OF THE FORECAST AREA WHERE AXIS OF STRONGEST ISENTROPIC LIFT COMBINES WITH A PERIOD WITH GREATER VERTICAL VELOCITIES AND A SLIGHTLY DEEPER DENDRITIC GROWTH ZONE. WITH SNOW RATIOS LIKELY TO BE ELEVATED AND CLOSER TO 15 TO 1 IN THESE AREAS...FEEL COMFORTABLE PLACING A GENERAL 1 TO 2 INCHES THROUGH FRIDAY AFTERNOON NORTHEAST OF A ROCKVILLE-MARTINSVILLE- COLUMBUS LINE WITH AMOUNTS DROPPING OFF QUICKLY TO THE SOUTH OF THAT LINE. OP GFS EVEN HINTS AT DEVELOPMENT OF A TROWAL OVER OHIO FRIDAY MORNING WHICH MAY SERVE TO ENHANCE LIFT EVEN A TOUCH MORE OVER NORTHEAST COUNTIES AND ENABLE A FEW SPOTS FROM KOKOMO TO MUNCIE AND WINCHESTER TO MAKE A RUN AT 2 TO 3 INCHES FOR A FINAL TALLY. DRIER AIR WILL ADVECT INTO THE REGION FROM THE WEST RATHER QUICKLY ON FRIDAY AFTERNOON...SHUTTING OFF LIGHT SNOW FOR MOST OF THE REGION AND POTENTIALLY EVEN LEADING TO SOME CLEARING LATE. HAVE HELD ONTO LOW CHANCE POPS HOWEVER THROUGH THE REST OF THE AFTERNOON OVER NORTHEAST HALF OF THE FORECAST AREA AS A SECONDARY WAVE ALOFT DROPS THROUGH THE LOWER GREAT LAKES WITH THE SURFACE LOW AND MAY SERVE TO MAINTAIN SCATTERED LIGHT SNOW SHOWERS OR FLURRIES. ANY LINGERING FLURRIES WILL END OVER NORTHEAST COUNTIES FRIDAY EVENING WITH HIGH PRESSURE REESTABLISHING OVER THE REGION FOR THE REMAINDER OF THE SHORT TERM. THE HIGH WILL BRING ANOTHER SHOT OF COLDER AIR FOR FRIDAY NIGHT AND SATURDAY...BUT WARM ADVECTION WILL COMMENCE SATURDAY NIGHT AS THE HIGH MOVES OFF TO THE EAST AND RIDGING ALOFT EXPANDS INTO THE OHIO VALLEY. MID AND HIGH LEVEL CLOUD COVER WILL INCREASE LATE SATURDAY NIGHT AS LOW PRESSURE AND AN ASSOCIATED WARM FRONT LIFTS OUT OF THE CENTRAL PLAINS. TEMPS...PREFERRED COOLER METMOS GUIDANCE FOR HIGHS FRIDAY AS CLOUDS AND PRECIP FOR MUCH OF THE DAY FOLLOWED BY COLD ADVECTION. MAVMOS LOOKED REASONABLE FOR HIGHS SATURDAY PRIMARILY IN THE MID AND UPPER 20S. TRENDED TOWARDS MAVMOS FOR LOWS TONIGHT...THEN GENERALLY WENT AT OR A COUPLE DEGREES BELOW GUIDANCE FOR FRI/SAT NIGHTS CONSIDERING MAY HAVE A THIN SNOW COVER IN SOME SPOTS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... ISSUED AT 327 AM EST THU JAN 24 2013 AN ACTIVE WEATHER PATTERN SETS UP IN THE LONG TERM WITH AN UPPER TROUGH MOVING THROUGH THE PACIFIC NORTHWEST INTO THE CENTRAL U.S. THROUGH THE PERIOD. A SERIES OF UPPER SHORTWAVES WILL EJECT FROM THE UPPER TROUGH AND BRING CHANCES FOR PRECIPITATION TO THE AREA. AT THE SURFACE A WARM FRONT WILL FORM SOUTH OF THE AREA AND SLOWLY MOVE NORTH BEFORE THE SURFACE LOW EJECTS FROM THE PLAINS AND TRAVERSES THE GREAT LAKES. MODELS HAVE SOME MINOR DISAGREEMENTS IN TIMING/TEMPERATURES EARLY WITH SIGNIFICANT DIFFERENCES BY TUESDAY NIGHT. GENERALLY ACCEPTED ALLBLEND INITIALIZATION. BIGGEST CHALLENGE WILL BE PRECIPITATION TYPE FOR SUNDAY-MONDAY. ENTIRE COLUMN IS BELOW FREEZING SUNDAY MORNING BEFORE PRECIPITATION ARRIVES. BY SUNDAY AFTERNOON WITH UPPER SHORTWAVE APPROACHING ECMWF AND GFS SHOW AN INTRUSION OF WARM AIR ALOFT INTO THE SOUTHWEST AND BY SUNDAY NIGHT THIS MOVES ALL ACROSS THE AREA. MOST OF THE AREA SHOULD SEE A PROGRESSION FROM A CHANCE FOR SNOW TO A CHANCE FOR SNOW AND SLEET TO A CHANCE FOR FREEZING RAIN AND SLEET BEFORE TRANSITIONING TO RAIN. TRIED TO MATCH TRANSITION UP WITH FORECAST SOUNDINGS AND PARTIAL THICKNESSES...BUT BOTTOM LINE IS MUCH OF THE AREA WILL SEE SOME TYPE OF WINTRY MIX BEFORE THE TRANSITION TO ALL RAIN WHICH SHOULD OCCUR BY SOMETIME MONDAY MORNING. THEN CHANCES FOR RAIN WILL BE THE RULE UNTIL WEDNESDAY WHEN PRECIP TYPE IS UP IN THE AIR BECAUSE OF AFOREMENTIONED SIGNIFICANT MODEL TEMPERATURE DIFFERENCES. ANOTHER ITEM OF NOTE IS THE STRENGTH OF THE SYSTEM EJECTING FROM THE PLAINS TUESDAY/TUESDAY NIGHT. IF THE VERY WARM GFS WERE TO VERIFY COULD SEE CHANCES FOR THUNDER EEK THIS FAR NORTH. WILL LEAVE OUT FOR NOW AS ECMWF PAINTS A MUCH DIFFERENT PICTURE AND WOULD RATHER HAVE SOME AGREEMENT TO INCLUDE THUNDER THIS TIME OF YEAR. && .AVIATION /DISCUSSION FOR 241200Z TAF ISSUANCE/... ISSUED AT 549 AM EST THU JAN 24 2013 MAINLY VFR CONDITIONS AT THE SITES THROUGH THE PERIOD. THE ONLY EXCEPTION TO THIS COULD BE OVER THE NEXT COUPLE OF HOURS WITH LAKE EFFECT SNOW SHOWERS CONTINUING TO DRIFT SOUTH. THESE LEFTOVER ECHOES COULD BRIEFLY DROP KIND AND KBMG TO MVFR BUT DO NOT EXPECT THIS TO LAST FOR LONG. COULD ACTUALLY BE FINISHED ISSUANCE TIME AT KIND BUT MAY INCLUDE A BRIEF MENTION AT KBMG FOR MVFR CEILINGS. AFTER THAT ONLY SOME CIRRUS EXPECTED THROUGH THE DAY. A CLIPPER SYSTEM WILL APPROACH NEAR THE END OF THE PERIOD AND BRING LOWERING CEILINGS...BUT DON/T EXPECT AN IMPACT ON FLYING CONDITIONS UNTIL THE EXTENDED PORTION OF THE TAF. WINDS WILL SHIFT FROM NORTHWEST TO NORTHEAST LATER THIS MORNING BEFORE BECOMING SOUTHEASTERLY THIS EVENING. SPEED GENERALLY 5 TO 12 KTS WITH NO GUSTS EXPECTED. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM....CP AVIATION...CP
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
524 AM CST THU JAN 24 2013 ...UPDATED FOR THE AVIATION DISCUSSION... .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 347 AM CST THU JAN 24 2013 A SHORTWAVE TROUGH WAS MOVING SOUTHEAST INTO THE GREAT LAKES REGION THIS MORNING AND COLD HIGH PRESSURE WAS PUSHING SOUTH IN ITS WAKE. THE WESTERN EDGE OF THIS COLD AIR WAS MOVING INTO SOUTHWEST KANSAS IN UPSLOPE FASHION FROM THE NORTHEAST. MEANWHILE, THE NEXT SHORTWAVE TROUGH WAS PROGRESSING ACROSS THE PACIFIC NORTHWEST EARLY THIS MORNING. THIS SYSTEM WILL APPROACH THE NORTHERN HIGH PLAINS BY THIS AFTERNOON AND RESULT IN SURFACE TROUGHING IN THE LEE OF THE NORTHERN ROCKIES. IF THIS SYSTEM WAS FASTER, THE ASSOCIATED PACIFIC COLD FRONT WOULD HAVE NO PROBLEM SCOURING THE SHALLOW COLD AIR OUT OF WESTERN KANSAS. HOWEVER, IT APPEARS THAT THE COLD FRONTAL PASSAGE WILL HOLD OFF UNTIL LATER TONIGHT. ALSO, THE LEE TROUGH AND ASSOCIATED SOUTHERLY WINDS AHEAD OF THE SYSTEM ARE NOT ADVERTISED TO BE STRONG ENOUGH TO SCOUR OUT THE COLD AIR. INSTEAD, THE ISENTROPIC LIFT WITH THE DEVELOPING SOUTHERLIES WILL AID IN LOW CLOUD DEVELOPMENT THIS MORNING AND A WEAK UPSLOPE COMPONENT WILL PERSIST AT LOWER LEVELS THROUGH THE DAY. THE NAM SOUNDINGS SHOW A SHALLOW LAYER OF SATURATION ABOVE 900MB AND THIS IS REASONABLE BASED ON THE HIGHER OBSERVED SURFACE DEWPOINTS CURRENTLY RESIDING ACROSS OKLAHOMA. ALSO, PLENTY OF HIGH LEVEL CLOUD WAS PRESENT ACROSS KANSAS THIS MORNING AND SHOULD PERSIST THROUGH THE DAY AND FURTHER LIMIT INSOLATION. THEREFORE, TEMPERATURES FROM DODGE CITY EASTWARD WILL STAY AT OR BELOW FREEZING. SOME COLD AIR EROSION IS EXPECTED IN FAR WESTERN KANSAS WHERE TEMPERATURES COULD REACH INTO THE UPPER 30S AND 40S. THE OFFICIAL FORECAST WILL BE A FEW DEGREES COLDER THAN THE NAM. FOR SOME REASON THE RAP ERODES THE COLD AIR WITH HIGHS IN THE MID 40S EVEN AS FAR EAST AS DODGE CITY. BY TONIGHT, THE LOW LEVEL WINDS ARE EXPECTED TO VEER TO THE SOUTHWEST AS THE AFOREMENTIONED PACIFIC COLD FRONT APPROACHES. THUS THE LOW CLOUDS WILL RAPIDLY CLEAR OUT. TEMPERATURES WILL INITIALLY FALL INTO THE 20S OVERNIGHT BUT THEN HOLD STEADY OR EVEN RISE AFTER 3 AM AS VERTICAL MIXING INCREASES BEHIND THE PACIFIC COLD FRONT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 330 AM CST THU JAN 24 2013 FRIDAY WILL START WITH THE UPPER LEVEL FLOW OVER KANSAS IN A SLIGHT DOWNSLOPE PATTERN WITH NORTHWEST FLOW ALOFT. SKIES SHOULD START OUT FRIDAY MORNING SUNNY, WITH LIGHT NORTH TO NORTHWEST SURFACE WINDS. BY FRIDAY AFTERNOON, A FEW HIGH CIRRUS CLOUDS WILL STREAM IN WITH SKIES BECOMING MOSTLY SUNNY, AND WINDS SHIFTING TO THE SOUTH AT 10 MPH OR LESS. CLOUDS WILL CONTINUE TO INCREASE FRIDAY NIGHT. WINDS WILL REMAIN SOUTH AT AROUND 10 MPH, SO MINIMUM TEMPS WILL BE MILD IN THE MID 20S TO LOWER 30S. ON SATURDAY, AN UPPER LEVEL WAVE WILL BE APPROACHING FROM THE SOUTHWEST. PLENTY OF MOISTURE IS STILL SITTING OVER TEXAS AND WILL STILL BE THERE SATURDAY. THE DEEP, SOUTHWEST FLOW ALOFT WILL ADVECT SOME OF THAT MOISTURE NORTH INTO KANSAS. WHEN THAT UPPER WAVE APPROACHES LATE SATURDAY, THE MOISTURE WILL BE IN PLACE. THERE ARE SLIGHT CHANCES FOR RAIN IN OUR EAST VERY LATE ON SATURDAY, BUT PRECIPITATION CHANCES WILL INCREASE SATURDAY NIGHT AS THE UPPER LIFT MOVES IN. PRECIPITATION CHANCES WILL BE AS HIGH AS 50 PERCENT IN OUR EAST AND SOUTHEAST, BASICALLY EAST OF HIGHWAY 19. AS FOR PRECIPITATION, RAIN WILL DOMINATE, AND RAINFALL AMOUNTS WILL BE ON THE LIGHT SIDE. THE GFS MODEL HAS THE MOST PRECIP, WITH 0.25 IN OUR EAST, BUT THE GEM AND THE ECMWF MODELS BOTH PRODUCE LESS THAN A TENTH OF AN INCH OF RAINFALL SATURDAY AND SUNDAY MORNING. SUNDAY, PRECIP CHANCES WILL JUST BE ACROSS OUR EXTREME EASTERN TIER OF COUNTIES, FROM ELLIS SOUTH TO BARBER COUNTY. AFTER THIS WAVE PASSES SUNDAY, THE UPPER PATTERN WILL TURN TO THE SOUTHWEST, WITH A WARMING TREND. BY TUESDAY, MAX TEMPS SHOULD BE WELL INTO THE MID 50S NORTH OF I-70 TO THE MID 60S SOUTH ALONG THE OKLAHOMA BORDER. A LARGE, BROAD SCALE UPPER TROUGH WILL BE MOVING INTO THE PLAINS TUESDAY INTO WEDNESDAY, AND A LOW END SLIGHT CHANCE FOR RAIN WILL EXIST OVER OUR NORTHERN MOST COUNTIES OF ELLIS AND TREGO. I AM NOT TOO CONFIDENT IN THESE PRECIPITATION CHANCES TUESDAY AND WEDNESDAY, SO STAYED WITH LOW 15-16 PERCENT CHANCES ONLY, FOR NOW. FOR MOST OF THIS EXTENDED FORECAST, THE ECMWF MODEL WAS FAVORED. THE GFS SEEMS TOO WET AND SLOWER WITH THE UPPER PROGRESSION OF WAVES. THE GEM CANADIAN MODEL ON THE OTHER HAND IS FASTER AND LESS WET. THUS, THE ECMWF IS A GOOD COMPROMISE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 513 AM CST THU JAN 24 2013 AS THE SURFACE FLOW CONTINUES FROM THE EAST AND UPSLOPE IN NATURE, LOW STRATUS CLOUDS WILL CONTINUE TO DEVELOP AND SPREAD FROM WEST TO EAST. THIS WILL RESULT IN IFR CIGS AT GCK AND POSSIBLY HYS, AND IN THE MVFR CATEGORY AT DDC. LATER THIS EVENING, THE CLOUDS SHOULD BREAK UP AND VFR CONDITIONS DEVELOP, AS WINDS BECOME FROM THE SOUTH AT AROUND 10 MPH. && .PRELIMINARY POINT TEMPS/POPS... DDC 32 25 52 27 / 0 0 0 0 GCK 37 25 52 28 / 0 0 0 0 EHA 47 27 53 32 / 0 0 0 0 LBL 38 26 53 29 / 0 0 0 0 HYS 32 22 50 26 / 0 0 0 0 P28 29 27 53 26 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...FINCH LONG TERM...BURKE AVIATION...BURKE
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
708 AM EST THU JAN 24 2013 .SYNOPSIS... A CLIPPER SYSTEM MOVES ACROSS THE MID ATLANTIC REGION THIS MORNING. HIGH PRESSURE BUILDS IN FROM THE NORTH THURSDAY AND SETTLES OVER THE AREA THURSDAY NIGHT. ANOTHER LOW PRESSURE SYSTEM CROSSES THE REGION FRIDAY AFTERNOON INTO FRIDAY EVENING...BEFORE HIGH PRESSURE RETURNS FOR THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... SNOW IS TAPERING OFF ACROSS THE REGION THIS MORNING. THE WINTER WEATHER ADVISORY HAS BEEN CANCELLED FOR THE CENTRAL VA PIEDMONT AND MIDDLE PENINSULA AS VERY LITTLE TO NO ADDITIONAL ACCUMULATION IS EXPECTED. HOWEVER...SLICK SPOTS COULD CONTINUE ON OVERPASSES AND SECONDARY ROADS FOR THE NEXT FEW HOURS. FARTHER EAST...THE ADVISORY HAS BEEN MAINTAINED AS A FEW LIGHT BANDS OF SNOW CONTINUE TO AFFECT THE EASTERN SHORE. ADDITIONAL ACCUMULATION SHOULD BE LESS THAN ONE INCH. PREVIOUS DISCUSSION... A CLIPPER SYSTEM IS PRESENTLY AFFECTING THE AREA WITH SNOW FALLING FROM THE CENTRAL VA PIEDMONT TO THE EASTERN SHORE. THE HEAVIEST BAND PER 88D RADAR MOSAIC AS DEVELOPED ROUGHLY ALONG A LINE FROM EZF-NUI-WAL WITH ADDITIONAL ENHANCEMENT OF ECHOES OVER THE MIDDLE PENINSULA. 24/06Z RUC DATA INDICATES ROBUST FRONTOGENETIC FORCING PERSISTING FROM THE NRN NECK/MIDDLE PENINSULA TO THE EASTERN SHORE OVER THE NEXT FEW HOURS BEFORE DECLINING WNW-ESE FROM ABOUT 12-14Z. GIVEN THIS THERE IS RATHER HIGH CONFIDENCE OF 1-2IN OF SNOW ACCUMULATION WITH ISOLATED AMOUNTS TO 3IN POSSIBLE IN THE HEAVIEST BAND. RUC DATA ALSO SUGGEST THE BEST WAA BEGINS TO DIMINISH OVER THE PIEDMONT DURING THE NEXT FEW HOURS...BUT GIVEN THE PERSISTENCE OF LIGHT SNOW OVER THE PAST FEW HOURS SOME LOCATIONS COULD RECEIVE A TOTAL SNOW ACCUMULATION OF 1 TO PERHAPS 2IN. A WINTER WEATHER ADVISORY HAS BEEN ISSUED TO ACCOUNT FOR THIS. THE ENTIRE ADVISORY IS IN ONE SEGMENT ENDING AT 15Z (10AM) FOR SIMPLICITY...BUT WESTERN AREAS WILL LIKELY SEE AN IMPROVEMENT WELL BEFORE THEN. A PORTION OF THE MAIN POLAR VORTEX DROPS SE ACROSS NY OVERNIGHT TOWARD LONG ISLAND BY MIDDAY. THIS TRIGGERS THE CLIPPER TO STRENGTHEN OFFSHORE DRIVING STRONG CAA ACROSS THE MID ATLANTIC THIS MORNING. FORECAST SOUNDINGS INDICATE STEEP LOW-LEVEL LAPSE RATES WITH LINGERING MOISTURE FROM ABOUT 950-750MB RESULTING IN SOME LIMITED CONVECTIVE INSTABILITY. HENCE THERE IS A POTENTIAL FOR SCATTERED OR PERHAPS A BROKEN LINE OF SNOW SHOWERS TRACKING N-S THROUGH THE MORNING FROM EASTERN VA TO NE NC AS SUGGESTED BY HIGH-RES MODEL DATA. A RATHER QUICK CLEARING TREND IS EXPECTED FROM NW-SE BY AFTERNOON ALTHOUGH CHILLY TEMPERATURES WILL CONTINUE. HIGHS SHOULD RANGE FROM THE UPPER 20S/LOW 30S N...TO MID 30S S. A 15-20MPH N WIND WITH GUSTS TO 25 MPH WILL PRODUCE WIND CHILL VALUES OF 15-20 THROUGH MUCH OF THE DAY. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... A 1035MB ARCTIC (IN ORIGIN) HIGH BUILDS INTO THE MID ATLANTIC TONIGHT. MEANWHILE...ANOTHER CLIPPER DIVES SE ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST. HIGH THIN CIRRUS WILL LIKELY BEGIN TO OVERSPREAD THE REGION LATE...BUT MOST OF THE NIGHT SHOULD REMAIN CLEAR TO MOSTLY CLEAR. THIS WILL ALLOW TEMPERATURES TO DROP OFF VERY QUICKLY EVENTUALLY PLUMMETING TO 10-15 ASIDE FROM 15-20 FOR EXTREME SE COASTAL LOCATIONS. AREAS WITH SNOW COVER FROM THE CURRENT CLIPPER COULD FALL TO 5-10...ESPECIALLY OVER THE EASTERN SHORE WHERE THE SKY SHOULD REMAIN CLEAR FOR THE LONGEST DURATION. HIGH PRESSURE REMAINS OVER THE REGION TO BEGIN THE DAY FRIDAY BEFORE SHIFTING OFFSHORE DURING THE AFTERNOON AS THE NEXT CLIPPER APPROACHES FROM THE WEST. THE INITIAL SHORTWAVE REMAINS WELL N OF THE REGION...BUT SECONDARY SHORTWAVE ENERGY TRIGGERS A WEAK LOW ALONG THE ARCTIC BOUNDARY...WHICH TRACKS ACROSS NC BEFORE MOVING OFF THE COAST AND DEEPENING WELL OFFSHORE FRIDAY NIGHT. MOISTURE INCREASES ALOFT THROUGHOUT THE MORNING. HOWEVER...THE LOWER LEVELS WILL REMAIN VERY DRY AND FORECAST SOUNDING DO NOT INDICATE SATURATION UNTIL 18-21Z FOR THE PIEDMONT...AND 21-00Z FOR I-95 EAST. DRY AIR ALOFT THEN QUICKLY INTRUDES THROUGH THE EVENING AS THE LOW DEEPENS OFFSHORE. GIVEN THIS...QPF AMOUNTS WILL BE LIGHT AND EVEN 0.25IN SEEMS DIFFICULT TO ACHIEVE. THE BEST FRONTOGENETIC FORCING APPEARS TO SET-UP FROM S-CENTRAL/SE VA TO THE EASTERN SHORE DURING A SHORT PERIOD FORM LATE FRIDAY AFTERNOON INTO FRIDAY EVENING. P-TYPE SHOULD PRIMARILY BE SNOW. HOWEVER...WITH SSW FLOW A MIX OR CHANGE TO IP IS LIKELY OVER EXTREME SE VA AND NE NC. PORTIONS OF NE NC COULD EVEN HAVE THE PRECIP END AS A PERIOD OF LIGHT FREEZING DRIZZLE. ANY ICE ACCUMULATION SHOULD BE MINIMAL. AS FOR SNOW ACCUMULATION...A BAND OF 1-2IN IS EXPECTED FROM INTERIOR NE NC ACROSS S-CENTRAL/SE VA...WHILE 2-3IN IS POSSIBLE OVER THE EASTERN SHORE. ELSEWHERE...SNOW ACCUMULATION SHOULD BE AN INCH OR LESS. HIGHS FRIDAY SHOULD RANGE FROM THE UPPER 20 NW...TO THE MID/UPPER 30S SE (PRIOR TO PRECIP EVAPORATING INTO THE AMBIENT AIRMASS). DRY NW FLOW PREVAILS SATURDAY AS THE LOW STRENGTHENS WELL OFF THE COAST AND SFC HIGH PRESSURE RETURNS. LOWS SHOULD RANGE FROM THE UPPER TEENS NW...TO MID 20S SE...FOLLOWED BY HIGHS RANGING FROM THE LOW/MID 30S N...TO AROUND 40 S. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... GOING WITH A COMBINATION OF THE 12Z GFS AND 12Z ECMWF MODELS FOR THE EXTENDED PERIOD. DRY AND COLD CONDITIONS EXPECTED INITIALLY SAT NGT AND SUN...THEN MILDER...ABOVE NORMAL TEMPS FCST FOR TUE AND WED. HI PRES WILL BLD INTO AND OVR THE AREA SAT NGT AND SUN...THEN SLIDE OFF THE CST FOR MON INTO WED. THERE COULD BE ISLTD RAIN SHOWERS...ESPLY ACRS EXTRM NW OR NRN CNTIES MON AFTN THRU TUE NEAR A WARM FRONT. OTHRWISE...A BETTER CHC FOR RAIN SHOWERS WILL BE DURING WED...AS A COLD FRONT PUSHES INTO THE REGION. MIN TEMPS WILL RANGE FM THE UPR TEENS TO MID 20S SUN MORNG...IN THE MID 20S TO NEAR 30 MON MORNG...IN THE MID 30S TO LWR 40S TUE MORNG...AND IN THE 40S WED MORNG. MAX TEMPS WILL RANGE FM THE MID 30S TO LWR 40S SUN...IN THE 40S TO NEAR 50 MON...IN THE LWR 50S TO LWR 60S TUE...AND MAINLY IN THE UPR 50S TO MID 60S WED. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... LGT SNOW WILL COME TO AN END AT RIC/SBY OVER NEXT COUPLE HRS. HELD ONTO IFR CONDITIONS UNTIL 13Z AT RIC AND 14Z AT SBY...IMPROVING TO MVFR FOR A COUPLE HRS BEFORE BCMG VFR FOR THE REMAINDER OF THE DAY. CLIPPER SYSTM MOVES OFFSHORE TDY...WITH WINDS SHIFTING TO THE N/NW BEHIND THE SYSTM. WINDS WILL BE GUSTY THRU MIDDAY AND AFTN DUE TO A TIGHTENING PRESSURE GRADIENT AS THE SYSTM STRENGTHENS OFFSHORE AND STRONG HI PRES BLDS IN FROM THE WEST. ANOTHER LO PRES SYSTEM MAY BRING A PERIOD OF SNOW (MIXED PCPN FOR ECG) TO THE AREA FRI AFTN/EVENG WITH BRIEF PERIODS OF IFR POSSIBLE. DRY WX AND VFR CONDITIONS EXPECTED FOR SAT AND SUN. && .MARINE... ALL MARINE HEADLINES ARE NOW IN EFFECT WITH CONDITIONS EXPECTED WITHIN 12 HR. AREA OF LO PRES CURRENTLY OVER THE AREA WILL PUSH OFFSHORE THRU THE MRNG HRS...ALLOWING FOR WINDS TO BECOME N/NW OVER ALL WATERS BY MID MRNG. STRONG SFC PRES RISES WEST OF THE AREA AND CAA WILL LEAD TO GALE CONDITIONS OVER THE SOUND/MOUTH OF THE BAY/COASTAL WATERS SOUTH OF PARRAMORE ISLAND...WITH STRONG SCA CONDITIONS OVER ALL OTHER WATERS. GALE FORCE WINDS WILL LAST UNTIL ERLY THIS EVENG WHEN CAA CEASES...WITH GALE HEADLINES LIKELY BEING REPLACED BY A SCA. EXPECT 5-7 FT SEAS OVER COASTAL WATERS AND 3-5 FT WAVES OVER THE BAY TDY. STRONG HI PRES BLDS DIRECTLY OVER THE AREA LATE TNGT INTO FRI AS MARINE CONDITIONS IMPROVE. WINDS BECOME SOUTHERLY ~10 KT FRI AFTN AS THE HI MOVES OFFSHORE. AN AREA OF LO PRES WILL TRACK INTO THE AREA LATE FRI...STRENGTHENING AS IT PUSHES OFFSHORE FRI NGT INTO SAT. SCA CONDITIONS ARE EXPECTED BEHIND THIS SYSTM WITH GUSTS UP TO GALE FORCE POSSIBLE...ESPECIALLY OVER COASTAL WATERS. && .HYDROLOGY... FLOOD WARNING REMAINS IN EFFECT FOR THE NOTTOWAY RIVER AT SEBRELL. THE RIVER CONTINUES TO TREND DOWNWARD. SEE LATEST FLSAKQ/FLWAKQ FOR DETAILS. && .CLIMATE... AT RICHMOND...YESTERDAY`S HIGH WAS ABOVE 32 F...NOW MAKING IT 732 CONSECUTIVE DAYS WITH A HIGH ABOVE 32 F (AND STILL COUNTING). THE PREVIOUS LONGEST STREAK HAD BEEN 730 DAYS (12/27/1948 TO 12/26/1950). IT WILL BE CLOSE THURSDAY AS THE LATEST FORECAST IS FOR HIGHS NEAR 32 F. NOTE: NORFOLK HAS SET NO RECORDS WITH REGARD TO THESE CRITERIA. WELL BELOW AVERAGE TEMPERATURES CONTINUE THURSDAY BUT STILL NOT GOING TO CHALLENGE ANY RECORDS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR MDZ021>025. NC...NONE. VA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ075>078-099-100. MARINE...GALE WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ633-634-654- 656-658. SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR ANZ630>632-650- 652. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ635>638. && $$ SYNOPSIS...AJZ NEAR TERM...AJZ SHORT TERM...AJZ LONG TERM...TMG AVIATION...MAS MARINE...MAS HYDROLOGY... CLIMATE...
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
648 AM EST THU JAN 24 2013 .SYNOPSIS... A CLIPPER SYSTEM MOVES ACROSS THE MID ATLANTIC REGION THIS MORNING. HIGH PRESSURE BUILDS IN FROM THE NORTH THURSDAY AND SETTLES OVER THE AREA THURSDAY NIGHT. ANOTHER LOW PRESSURE SYSTEM CROSSES THE REGION FRIDAY AFTERNOON INTO FRIDAY EVENING...BEFORE HIGH PRESSURE RETURNS FOR THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A CLIPPER SYSTEM IS PRESENTLY AFFECTING THE AREA WITH SNOW FALLING FROM THE CENTRAL VA PIEDMONT TO THE EASTERN SHORE. THE HEAVIEST BAND PER 88D RADAR MOSAIC AS DEVELOPED ROUGHLY ALONG A LINE FROM EZF-NUI-WAL WITH ADDITIONAL ENHANCEMENT OF ECHOES OVER THE MIDDLE PENINSULA. 24/06Z RUC DATA INDICATES ROBUST FRONTOGENETIC FORCING PERSISTING FROM THE NRN NECK/MIDDLE PENINSULA TO THE EASTERN SHORE OVER THE NEXT FEW HOURS BEFORE DECLINING WNW-ESE FROM ABOUT 12-14Z. GIVEN THIS THERE IS RATHER HIGH CONFIDENCE OF 1-2IN OF SNOW ACCUMULATION WITH ISOLATED AMOUNTS TO 3IN POSSIBLE IN THE HEAVIEST BAND. RUC DATA ALSO SUGGEST THE BEST WAA BEGINS TO DIMINISH OVER THE PIEDMONT DURING THE NEXT FEW HOURS...BUT GIVEN THE PERSISTENCE OF LIGHT SNOW OVER THE PAST FEW HOURS SOME LOCATIONS COULD RECEIVE A TOTAL SNOW ACCUMULATION OF 1 TO PERHAPS 2IN. A WINTER WEATHER ADVISORY HAS BEEN ISSUED TO ACCOUNT FOR THIS. THE ENTIRE ADVISORY IS IN ONE SEGMENT ENDING AT 15Z (10AM) FOR SIMPLICITY...BUT WESTERN AREAS WILL LIKELY SEE AN IMPROVEMENT WELL BEFORE THEN. A PORTION OF THE MAIN POLAR VORTEX DROPS SE ACROSS NY OVERNIGHT TOWARD LONG ISLAND BY MIDDAY. THIS TRIGGERS THE CLIPPER TO STRENGTHEN OFFSHORE DRIVING STRONG CAA ACROSS THE MID ATLANTIC THIS MORNING. FORECAST SOUNDINGS INDICATE STEEP LOW-LEVEL LAPSE RATES WITH LINGERING MOISTURE FROM ABOUT 950-750MB RESULTING IN SOME LIMITED CONVECTIVE INSTABILITY. HENCE THERE IS A POTENTIAL FOR SCATTERED OR PERHAPS A BROKEN LINE OF SNOW SHOWERS TRACKING N-S THROUGH THE MORNING FROM EASTERN VA TO NE NC AS SUGGESTED BY HIGH-RES MODEL DATA. A RATHER QUICK CLEARING TREND IS EXPECTED FROM NW-SE BY AFTERNOON ALTHOUGH CHILLY TEMPERATURES WILL CONTINUE. HIGHS SHOULD RANGE FROM THE UPPER 20S/LOW 30S N...TO MID 30S S. A 15-20MPH N WIND WITH GUSTS TO 25 MPH WILL PRODUCE WIND CHILL VALUES OF 15-20 THROUGH MUCH OF THE DAY. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... A 1035MB ARCTIC (IN ORIGIN) HIGH BUILDS INTO THE MID ATLANTIC TONIGHT. MEANWHILE...ANOTHER CLIPPER DIVES SE ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST. HIGH THIN CIRRUS WILL LIKELY BEGIN TO OVERSPREAD THE REGION LATE...BUT MOST OF THE NIGHT SHOULD REMAIN CLEAR TO MOSTLY CLEAR. THIS WILL ALLOW TEMPERATURES TO DROP OFF VERY QUICKLY EVENTUALLY PLUMMETING TO 10-15 ASIDE FROM 15-20 FOR EXTREME SE COASTAL LOCATIONS. AREAS WITH SNOW COVER FROM THE CURRENT CLIPPER COULD FALL TO 5-10...ESPECIALLY OVER THE EASTERN SHORE WHERE THE SKY SHOULD REMAIN CLEAR FOR THE LONGEST DURATION. HIGH PRESSURE REMAINS OVER THE REGION TO BEGIN THE DAY FRIDAY BEFORE SHIFTING OFFSHORE DURING THE AFTERNOON AS THE NEXT CLIPPER APPROACHES FROM THE WEST. THE INITIAL SHORTWAVE REMAINS WELL N OF THE REGION...BUT SECONDARY SHORTWAVE ENERGY TRIGGERS A WEAK LOW ALONG THE ARCTIC BOUNDARY...WHICH TRACKS ACROSS NC BEFORE MOVING OFF THE COAST AND DEEPENING WELL OFFSHORE FRIDAY NIGHT. MOISTURE INCREASES ALOFT THROUGHOUT THE MORNING. HOWEVER...THE LOWER LEVELS WILL REMAIN VERY DRY AND FORECAST SOUNDING DO NOT INDICATE SATURATION UNTIL 18-21Z FOR THE PIEDMONT...AND 21-00Z FOR I-95 EAST. DRY AIR ALOFT THEN QUICKLY INTRUDES THROUGH THE EVENING AS THE LOW DEEPENS OFFSHORE. GIVEN THIS...QPF AMOUNTS WILL BE LIGHT AND EVEN 0.25IN SEEMS DIFFICULT TO ACHIEVE. THE BEST FRONTOGENETIC FORCING APPEARS TO SET-UP FROM S-CENTRAL/SE VA TO THE EASTERN SHORE DURING A SHORT PERIOD FORM LATE FRIDAY AFTERNOON INTO FRIDAY EVENING. P-TYPE SHOULD PRIMARILY BE SNOW. HOWEVER...WITH SSW FLOW A MIX OR CHANGE TO IP IS LIKELY OVER EXTREME SE VA AND NE NC. PORTIONS OF NE NC COULD EVEN HAVE THE PRECIP END AS A PERIOD OF LIGHT FREEZING DRIZZLE. ANY ICE ACCUMULATION SHOULD BE MINIMAL. AS FOR SNOW ACCUMULATION...A BAND OF 1-2IN IS EXPECTED FROM INTERIOR NE NC ACROSS S-CENTRAL/SE VA...WHILE 2-3IN IS POSSIBLE OVER THE EASTERN SHORE. ELSEWHERE...SNOW ACCUMULATION SHOULD BE AN INCH OR LESS. HIGHS FRIDAY SHOULD RANGE FROM THE UPPER 20 NW...TO THE MID/UPPER 30S SE (PRIOR TO PRECIP EVAPORATING INTO THE AMBIENT AIRMASS). DRY NW FLOW PREVAILS SATURDAY AS THE LOW STRENGTHENS WELL OFF THE COAST AND SFC HIGH PRESSURE RETURNS. LOWS SHOULD RANGE FROM THE UPPER TEENS NW...TO MID 20S SE...FOLLOWED BY HIGHS RANGING FROM THE LOW/MID 30S N...TO AROUND 40 S. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... GOING WITH A COMBINATION OF THE 12Z GFS AND 12Z ECMWF MODELS FOR THE EXTENDED PERIOD. DRY AND COLD CONDITIONS EXPECTED INITIALLY SAT NGT AND SUN...THEN MILDER...ABOVE NORMAL TEMPS FCST FOR TUE AND WED. HI PRES WILL BLD INTO AND OVR THE AREA SAT NGT AND SUN...THEN SLIDE OFF THE CST FOR MON INTO WED. THERE COULD BE ISLTD RAIN SHOWERS...ESPLY ACRS EXTRM NW OR NRN CNTIES MON AFTN THRU TUE NEAR A WARM FRONT. OTHRWISE...A BETTER CHC FOR RAIN SHOWERS WILL BE DURING WED...AS A COLD FRONT PUSHES INTO THE REGION. MIN TEMPS WILL RANGE FM THE UPR TEENS TO MID 20S SUN MORNG...IN THE MID 20S TO NEAR 30 MON MORNG...IN THE MID 30S TO LWR 40S TUE MORNG...AND IN THE 40S WED MORNG. MAX TEMPS WILL RANGE FM THE MID 30S TO LWR 40S SUN...IN THE 40S TO NEAR 50 MON...IN THE LWR 50S TO LWR 60S TUE...AND MAINLY IN THE UPR 50S TO MID 60S WED. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... LGT SNOW WILL COME TO AN END AT RIC/SBY OVER NEXT COUPLE HRS. HELD ONTO IFR CONDITIONS UNTIL 13Z AT RIC AND 14Z AT SBY...IMPROVING TO MVFR FOR A COUPLE HRS BEFORE BCMG VFR FOR THE REMAINDER OF THE DAY. CLIPPER SYSTM MOVES OFFSHORE TDY...WITH WINDS SHIFTING TO THE N/NW BEHIND THE SYSTM. WINDS WILL BE GUSTY THRU MIDDAY AND AFTN DUE TO A TIGHTENING PRESSURE GRADIENT AS THE SYSTM STRENGTHENS OFFSHORE AND STRONG HI PRES BLDS IN FROM THE WEST. ANOTHER LO PRES SYSTEM MAY BRING A PERIOD OF SNOW (MIXED PCPN FOR ECG) TO THE AREA FRI AFTN/EVENG WITH BRIEF PERIODS OF IFR POSSIBLE. DRY WX AND VFR CONDITIONS EXPECTED FOR SAT AND SUN. && .MARINE... ALL MARINE HEADLINES ARE NOW IN EFFECT WITH CONDITIONS EXPECTED WITHIN 12 HR. AREA OF LO PRES CURRENTLY OVER THE AREA WILL PUSH OFFSHORE THRU THE MRNG HRS...ALLOWING FOR WINDS TO BECOME N/NW OVER ALL WATERS BY MID MRNG. STRONG SFC PRES RISES WEST OF THE AREA AND CAA WILL LEAD TO GALE CONDITIONS OVER THE SOUND/MOUTH OF THE BAY/COASTAL WATERS SOUTH OF PARRAMORE ISLAND...WITH STRONG SCA CONDITIONS OVER ALL OTHER WATERS. GALE FORCE WINDS WILL LAST UNTIL ERLY THIS EVENG WHEN CAA CEASES...WITH GALE HEADLINES LIKELY BEING REPLACED BY A SCA. EXPECT 5-7 FT SEAS OVER COASTAL WATERS AND 3-5 FT WAVES OVER THE BAY TDY. STRONG HI PRES BLDS DIRECTLY OVER THE AREA LATE TNGT INTO FRI AS MARINE CONDITIONS IMPROVE. WINDS BECOME SOUTHERLY ~10 KT FRI AFTN AS THE HI MOVES OFFSHORE. AN AREA OF LO PRES WILL TRACK INTO THE AREA LATE FRI...STRENGTHENING AS IT PUSHES OFFSHORE FRI NGT INTO SAT. SCA CONDITIONS ARE EXPECTED BEHIND THIS SYSTM WITH GUSTS UP TO GALE FORCE POSSIBLE...ESPECIALLY OVER COASTAL WATERS. && .HYDROLOGY... FLOOD WARNING REMAINS IN EFFECT FOR THE NOTTOWAY RIVER AT SEBRELL. THE RIVER CONTINUES TO TREND DOWNWARD. SEE LATEST FLSAKQ/FLWAKQ FOR DETAILS. && .CLIMATE... AT RICHMOND...YESTERDAY`S HIGH WAS ABOVE 32 F...NOW MAKING IT 732 CONSECUTIVE DAYS WITH A HIGH ABOVE 32 F (AND STILL COUNTING). THE PREVIOUS LONGEST STREAK HAD BEEN 730 DAYS (12/27/1948 TO 12/26/1950). IT WILL BE CLOSE THURSDAY AS THE LATEST FORECAST IS FOR HIGHS NEAR 32 F. NOTE: NORFOLK HAS SET NO RECORDS WITH REGARD TO THESE CRITERIA. WELL BELOW AVERAGE TEMPERATURES CONTINUE THURSDAY BUT STILL NOT GOING TO CHALLENGE ANY RECORDS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR MDZ021>025. NC...NONE. VA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ049-063-064-072>078-083>086-099-100. MARINE...GALE WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ633-634-654- 656-658. SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR ANZ630>632-650- 652. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ635>638. && $$ SYNOPSIS...AJZ NEAR TERM...AJZ SHORT TERM...AJZ LONG TERM...TMG AVIATION...MAS MARINE...MAS HYDROLOGY... CLIMATE...
AREA FORECAST DISCUSSION
NWS RALEIGH NC
555 AM EST THU JAN 24 2013 .SYNOPSIS... AN ARCTIC COLD FRONT WILL USHER STRONG HIGH PRESSURE INTO THE CAROLINAS TODAY. A COMPLEX LOW PRESSURE SYSTEM WILL TRACK EAST ACROSS THE REGION ON FRIDAY. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 325 AM THURSDAY... TODAY: A POTENT UPPER LEVEL TROUGH OVER THE LOWER GREAT LAKES AT 06Z WILL DIG SOUTHEAST OFFSHORE THE MID-ATLANTIC COAST BETWEEN 12-18Z TODAY. AN ATTENDANT CLIPPER LOW WILL TRACK RAPIDLY EAST THROUGH NC/VA BETWEEN 06-12Z...PROGRESSING OFFSHORE AFTER SUNRISE. PRONOUNCED SUBSIDENCE IN THE WAKE OF THE UPPER LEVEL TROUGH WILL RESULT IN STRONG PRESSURE RISES OVER THE OH VALLEY AND MID-ATLANTIC THIS MORNING...DRIVING AN ARCTIC COLD FRONT RAPIDLY SOUTHWARD THROUGH CENTRAL NC BETWEEN 12-15Z. PRESSURE RISES AS GREAT AS 5-7 MB IN 3-HR ARE PROGGED OVER CENTRAL NC IN THE WAKE OF THE FRONT BETWEEN ROUGHLY 14-17Z...AND THE 06Z RAP INDICATES LOW-LEVEL FLOW BETWEEN 30-40 KT AT THE BEGINNING OF THAT TIME-FRAME (STRONGEST SE COASTAL PLAIN) WHEN THE MIXED LAYER WILL BE RAPIDLY DEEPENING IN ASSOC/W THE ONSET OF STRONG COLD ADVECTION. EXPECT STRONG NORTHERLY WINDS FOR A FEW HOURS IN THE IMMEDIATE WAKE OF THE FRONT...WITH PEAK SUSTAINED WINDS AS HIGH AS 20-30 MPH AND GUSTS AS HIGH AS 35-40 MPH FOR A BRIEF PERIOD...ESPECIALLY ACROSS PORTIONS OF THE SANDHILLS (CUMBERLAND) AND SE COASTAL PLAIN (WAYNE/SAMPSON). GIVEN A STRONG FRONTAL PASSAGE BY MID MORNING...WITH 1000-850 THICKNESSES PLUMMETING TO 1255-1265 METERS AND H85 TEMPS DECREASING TO -12 TO -15C BY MID AFTERNOON... EXPECT THAT TEMPS WILL STRUGGLE TO RISE AT ALL DURING THE DAY. WILL INDICATE HIGHS RANGING FROM THE LOWER 30S NORTH TO MID/UPPER 30S SOUTH. THE BEST FORCING ASSOC/W THE UPPER LEVEL WAVE WILL REMAIN NORTH OF CENTRAL NC THIS MORNING...OVER SOUTHEAST VA AND THE DELMARVA. H85 FRONTOGENESIS WILL STRENGTHEN OVER THE NORTHERN PIEDMONT BETWEEN 09-12Z...CONTRIBUTING TO OVERCAST CLOUD COVER WITH CEILINGS 3500-5000 FT AGL NORTH OF HWY 64. HOWEVER...THE ONSET OF LOW-LEVEL COLD ADVECTION WILL HELP TO `CANCEL OUT` FORCING ASSOC/W FRONTOGENESIS...AND A RELATIVELY DRY BOUNDARY LAYER WILL PROVIDE A FURTHER BARRIER FOR ANY LIGHT PRECIPITATION TO MAKE IT TO THE GROUND. INTERESTINGLY...H85 COLD ADVECTION WILL BE SO STRONG THAT TEMPS AT THAT LEVEL WILL FALL WITHIN THE ICE NUCLEATION ZONE (-12 TO -15C) NORTH OF HWY 64 THIS AFTERNOON...AND FCST SOUNDINGS SHOW A POTENTIAL FOR VERY SHALLOW DESTABILIZATION BETWEEN 17-21Z IN THE NE COASTAL PLAIN WHERE NORTHERLY FLOW WILL ADVECT LOW-LEVEL MOISTURE SOUTHWARD FROM THE MID-ATLANTIC COAST INTO EASTERN PORTIONS OF NC. AS A RESULT...IT IS POSSIBLE THAT ISOLD SNOW SHOWERS COULD DEVELOP OVER NORTHEASTERN NC THIS AFTERNOON. WITH THIS IN MIND...WILL INDICATE A SLIGHT CHANCE OF SHOWER SHOWERS OVER WARREN/HALIFAX AND EDGECOMBE COUNTIES BETWEEN 17-21Z...CONSISTENT WITH SIMULATED REFLECTIVITY OUTPUT FROM THE 00Z HIGH RES WRF-NMM. TONIGHT: EXPECT CLEAR SKIES OVERNIGHT AS ARCTIC HIGH PRESSURE BUILDS DIRECTLY OVER CENTRAL NC. LOWS WILL BE DRIVEN BY A COMBINATION OF COLD ADVECTION (EARLY ON) AND RADIATIONAL COOLING. WILL INDICATE LOWS RANGING FROM THE MID/UPPER TEENS TO LOWER 20S. -VINCENT && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... AS OF 240 AM THURSDAY... ...A LIGHT WINTRY MIX STILL POSSIBLE FRIDAY AND FRIDAY EVENING... THE TREND OF THE MODELS CONTINUES TO BE TOWARD A FLATTER MID/UPPER WAVE SOLUTION AND VERY LIGHT QPF... FOR FRIDAY AND FRIDAY EVENING AS THE SYSTEM MOVES THROUGH THE TENNESSEE AND LOWER OHIO VALLEY REGION ACROSS THE APPALACHIANS TO THE MID-ATLANTIC COAST. VERY COLD ARCTIC AIR WILL BE IN PLACE. HOWEVER... MOISTURE WILL BE LACKING FOR A SIGNIFICANT WINTER STORM. YET... WITH SUCH COLD AIR IN PLACE FRIDAY BEFORE THE LIGHT PRECIPITATION EVENT UNFOLDS... THIS COULD TURN OUT TO BE A MINIMAL PRECIPITATION / BUT HIGH IMPACT EVENT (I.E. THE 19JAN2005 LIGHT SNOW / HIGH IMPACT EVENT)... WHEN RDU MEASURED 1 INCH OF SNOW WITH 0.04 LIQUID EQUIVALENT / WITH TEMPERATURES IN THE MID 20S DURING THE AFTERNOON. THE LATEST MODELS CONTINUE TO INDICATE LOW QPF IN THE RANGE OF 0.1 TO 0.2 OF AN INCH... WITH MOST ENSEMBLE MEMBERS IN THE 0.05 TO 0.15 RANGE. THE MAJORITY OF THE PRECIPITATION TIMING IS FORECAST TO BE IN THE LATE MORNING OR EARLY AFTERNOON BEGIN TIME... EXCEPT DURING THE AFTERNOON IN THE SOUTHEAST... ENDING QUICKLY BY LATE AFTERNOON OR VERY EARLY EVENING. ALTHOUGH THE MODEL 1000/850 AND 850/700 THICKNESS FORECASTS CONTINUE TO SHOW DECENT SPREAD... THE FAVORED 00Z/EC CONTINUES TO INDICATE THE PREDOMINATE P-TYPE TO BE LIGHT SNOW NW (1280/1535M THICKNESSES) ...LIGHT SNOW WITH SLEET IN THE I-64 CORRIDOR (PARTIALS IN THE 1280S AND 1540S - ENDING WITH 1300 AND 1550 OR SO). SURFACE WET BULB FORECASTS KEEP TEMPERATURES IN THE 20S ALL DAY FROM RALEIGH WEST AND NORTH THROUGH THE PIEDMONT INTO THE BLUE RIDGE. THIS WILL BE THE AREA WHERE MEASURABLE SNOW AND SLEET IS FAVORED... WITH A CHANGE-OVER TO LIGHT FREEZING RAIN OR FREEZING DRIZZLE BY SUNSET OR SO (AS WE LOSE SATURATION IN THE ICE NUCLEATION ZONE ALOFT). SNOWFALL ACCUMULATIONS OF AROUND AN INCH APPEAR POSSIBLE. THIS IS WHERE A WINTER WEATHER ADVISORY WILL LIKELY BE NEEDED FRIDAY INTO FRIDAY EVENING IN LATER FORECASTS (ASSUMING THE MODELS DO NOT COMPLETELY DRY UP). IN THE CORRIDOR FROM THE FAR SOUTHERN PIEDMONT... NORTHERN SANDHILLS AND MUCH OF THE CENTRAL COASTAL PLAIN... MAINLY TO THE NORTH OF A LINE FROM LAURINBURG TO FAYETTEVILLE TO GOLDSBORO / SOUTH OF 1-64 SHOULD BEGIN WITH LIGHT SNOW/SLEET WITH A CHANGE-OVER TO LIGHT FREEZING RAIN WITH TRACE SNOW/SLEET (PREDOMINATE P-TYPES). SURFACE WET BULBS HERE ARE FORECAST TO REACH NEAR 32... PLACING THIS REGION IN LIKELY ADVISORY CRITERIA AS WELL. TO THE EAST AND SOUTH OF LAURINBURG TO FAYETTEVILLE TO GOLDSBORO... A COLD LIGHT RAIN MIXED WITH SLEET IS EXPECTED WITH WET BULBS 33-34 OR SO DURING THE AFTERNOON. BOTTOM LINE... DUE TO THE EXPECTED LIGHT NATURE OF THE PRECIPITATION EPISODE AND THE VERY COLD AIR IN PLACE FRIDAY INTO FRIDAY EVENING... THIS COULD VERY WELL TURN OUT TO BE A LOW PRECIPITATION... YET RATHER HIGH IMPACT EVENT. MODEL TRENDS CONTINUE TO DAMPEN THE WAVE AND LESSEN THE QPF WITH TIME... WHICH MAKES THIS ONLY A LOW TO MODERATE CONFIDENCE FORECAST FOR AMOUNTS. P-TYPE AND COLD AIR ARE HIGH CONFIDENCE... QPF IS LOW CONFIDENCE. CLOUDY AND COLD FRIDAY WITH LIGHT SNOW LIKELY NW... LIGHT SNOW/SLEET CENTRAL... AND MOSTLY LIGHT RAIN SE LATE MORNING THROUGH THE AFTERNOON. HIGHS 28 TO 35. FRIDAY NIGHT... PATCHY FREEZING RAIN/FREEZING DRIZZLE POSSIBLE EARLY... THEN CLEARING LATE. COLD WITH POTENTIAL BLACK ICE. LOWS IN THE 20S. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 200 AM THURSDAY... SATURDAY AND SUNDAY: ANOTHER MODIFIED ARCTIC AIR MASS DRIVEN BY A 1035+ SURFACE HIGH WILL DIVE SE ACROSS OUR REGION. THE COLDEST NIGHT WILL LIKELY BE SATURDAY NIGHT... ALTHOUGH SUNDAY NIGHT WILL BE NEARLY AS COLD... BUT WITH LIGHTER WINDS. EXPECT MOSTLY CLEAR SKIES WITH LOWS IN THE 15-20 RANGE. HIGHS IN THE MID 30S TO MID 40S NW TO SE. A STOUT WARMING TREND WILL BEGIN MONDAY... THEN BE FELT IN FULL FORCE BY TUE-WED. THE ARCTIC HIGH SHIFTS QUICKLY OFFSHORE MONDAY... FOLLOWED BY A MODERATING SW FLOW. HIGHS SHOULD SHOOT UP QUICKLY INTO THE MID 50S TO LOWER 60S MONDAY... AND REACH THE 60S TUE-WED. MUCH MILDER NIGHTS ARE EXPECTED AS WELL WITH LOWS IN THE MID 30S TO LOWER 40S BY TUE AND IN THE 40S WEDNESDAY. THE NEXT CHANCE OF RAIN APPEARS TO BE WEDNESDAY AS A COLD FRONT APPROACHES FROM THE WEST. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 600 AM THURSDAY... 24-HR TAF PERIOD: VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. A POSSIBLE EXCEPTION WILL BE THE RWI TERMINAL WHERE A BRIEF PERIOD OF MVFR CEILINGS WILL BE POSSIBLE BETWEEN 17-21Z. THE BIGGEST AVIATION CONCERN WILL BE STRONG NORTHERLY WINDS FOR SEVERAL HOURS IN THE WAKE OF A COLD FRONTAL PASSAGE EXPECTED TO OCCUR BETWEEN 12-15Z THIS MORNING...EARLIEST AT THE INT/GSO TERMINALS AND LATEST AT THE FAY TERMINAL. GIVEN STRONG PRESSURE RISES AND 30-40 KT FLOW IN A RAPIDLY DEEPENING MIXED LAYER BEHIND THE FRONT...EXPECT PEAK SUSTAINED WINDS OUT OF THE N/NNW AT 15-25 KT WITH GUSTS AS HIGH AS 30-35 KT IN THE IMMEDIATE 2-3 HOURS (BETWEEN 15-18Z) POST FROPA. WINDS WILL GRADUALLY WEAKEN TO 10-15 KT BY 21Z THIS AFTERNOON...BECOMING CALM BY 00Z. LOOKING AHEAD: DETERIORATING CONDITIONS ARE EXPECTED DURING THE DAY FRIDAY IN ASSOCIATION WITH A WEAK LOW PRESSURE SYSTEM MOVING EAST ACROSS THE REGION. EXPECT THAT CEILINGS WILL LOWER INTO THE MVFR CATEGORY EVERYWHERE BETWEEN 15-21Z FRI (EARLIEST INT/GSO AND LATEST FAY/RWI)...WITH LIGHT PRECIP AND POTENTIALLY IFR/LIFR CONDITIONS ASSOCIATED WITH A COLD AIR DAMMING WEDGE DURING THE LATE AFTERNOON AND EVENING. A WINTRY MIX IS EXPECTED AT THE INT/GSO/RDU/RWI TERMINALS...AND IFR/LIFR CONDITIONS ASSOCIATED WITH THE CAD WEDGE WOULD BE UNLIKELY TO IMPROVE UNTIL SATURDAY WHEN ARCTIC HIGH PRESSURE BUILDS INTO THE CAROLINAS. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...BADGETT LONG TERM...BADGETT AVIATION...VINCENT
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
657 AM CST THU JAN 24 2013 .AVIATION... METROPLEX... WIDESPREAD FOG WITH VISIBILITIES OF LESS THAN 1 MILE SHOULD BE MAINLY NORTH AND EAST OF THE METROPLEX TAF SITES THIS MORNING. HAVE PLACED 6SM BR...BUT BE AWARE THAT SOME BRIEF GROUND FOG MAY QUICKLY DROP VISIBILITIES TO 1SM OR LESS BETWEEN 13-16Z. SOUTHERLY WINDS SHOULD INCREASE TO AROUND 10 KNOTS BY 16Z WHICH SHOULD DISPERSE ANY REMAINING FOG. A COLD FRONT THAT EXTNEDS SOUTH OF A MCALESTER OKLAHOMA /KMLC/ TO WICHITA FALLS /KSPS/ TO PLAINVIEW /KPVW/ LINE AT 6 AM WILL MOVE INTO THE METROPLEX TAF SITES BETWEEN 01 AND 03Z. HAVE INDICATED 36007KT AT 03Z IN THE METROPLEX TAFS. AS MOISTURE IS LIFTED ABOVE THE FRONT...SOME MVFR STRATUS MAY DEVELOP BY 08Z. WACO...IFR CONDITIONS ARE EXPECTED IN THE WACO AREA THROUGH 16Z. AREAS OF FOG AND MAYBE LOW CLOUDS WILL AFFECT THE WACO AREA THIS MORNING. VISIBILITIES MAY BRIEFLY FALL TO 1/4 MILE OR LESS...BUT SHOULD MAINLY BE 1/2 MILE OR GREATER. VFR CONDITIONS SHOULD RETURN BETWEEN 16 AND 17Z. A COLD FRONT IS EXPECTED TO APPROACH WACO 09-10Z FRIDAY...SO HAVE PLACED A WIND SHIFT TO 32006KT AT 09Z. 58 && .UPDATE... DESPITE WINDS OF 5 TO 10 MPH...THE FOG HAS BECOME MORE WIDESPREAD THIS MORNING AND WILL UPDATE TO INCLUDE FOG THROUGH THE MID MORNING HOURS. AREAS ALONG THE RED RIVER ARE REPORTING DENSE FOG WHERE THE WINDS HAVE BECOME LIGHT. ELSEWHERE...DENSE FOG IS BEING REPORTED IN ISOLATED AREAS ACROSS THE EASTERN COUNTIES...EAST OF THE HWY 75/I-45 CORRIDORS. WILL ISSUE A DENSE FOG ADVISORY FOR THESE TWO AREAS. 82/JLD && .PREV DISCUSSION... /ISSUED 339 AM CST THU JAN 24 2013/ UPPER LEVEL RIDGE IS NOW CENTERED SOUTHWEST OF THE AREA WITH HIGH CLOUDS STREAMING OVER THE TOP OF THE RIDGE AND INTO THE STATE. AT THE SURFACE...SOME STRATUS CLOUDS ARE NOW DEVELOPING ACROSS SOUTHEAST TEXAS...BUT ARE MOVING TO THE EAST AND NORTHEAST. SOME LOW CLOUDS WILL OCCUR OVER THE SOUTHEASTERN COUNTIES THIS MORNING...BUT SHOULD DISSIPATE BEFORE MIDDAY. IN ADDITION...THERE IS SOME SCATTERED PATCHY OF FOG ASSOCIATED WITH THE LOW CLOUDS IN SOUTHEAST TEXAS. AT THIS TIME DO NOT HAVE FOG MENTIONED IN THE GRIDS AS CURRENT THINKING IS THAT MOST OF THE FOG WILL STAY JUST OUTSIDE OUR AREA...BUT WILL UPDATE IF THE FOG BECOMES MORE WIDESPREAD. WILL ALSO BE MONITORING FOR FOG DEVELOPMENT NEAR THE RED RIVER THIS MORNING AS A COLD FRONT APPROACHES AND THE WINDS BECOME LIGHT. THE COLD FRONT HAS NOW PUSHED INTO SOUTHERN OKLAHOMA WITH TEMPERATURES IN THE 30S AND 40S BEHIND THE FRONT. THIS FRONT WILL EDGE JUST SOUTH OF THE RED RIVER TODAY...RESULTING IN MUCH COOLER TEMPERATURES ACROSS OUR NORTHERN COUNTIES. HIGH TEMPERATURES THIS AFTERNOON WILL RANGE FROM THE UPPER 50S ALONG THE RED RIVER TO NEAR 80 DEGREES IN OUR SOUTHWESTERN COUNTIES. HIGH CLOUDS ACROSS THE REGION AND SOME LOWER LEVEL CLOUDS DEVELOPING BEHIND PARTS OF THE FRONT WILL KEEP TEMPERATURES ON THE COOLER SIDE OF GUIDANCE TODAY. YESTERDAY...IT APPEARED THAT THE FRONT WOULD STALL OR EVEN RETREAT A LITTLE NEAR THE RED RIVER TONIGHT. HOWEVER...HI-RES GUIDANCE INCLUDING THE RAP AND TEXAS TECH WRF ALL SUPPORT THE NAM WHICH BEGINS TO PUSH THE FRONT SOUTH TONIGHT. WITH THE COLD TEMPERATURES THAT ARE ALREADY OCCURRING BEHIND THE FRONT...THIS SOLUTION IS THE MOST PLAUSIBLE ONE AND WILL SHOW THE FRONT SLOWLY MOVING SOUTH AFTER SUNSET. THE FRONT WILL CONTINUE MOVING SOUTH ON FRIDAY...HAVING MADE ITS WAY ALMOST ENTIRELY THROUGH THE CWA BY MIDDAY. TEMPERATURES TONIGHT WILL AGAIN BE VARIABLE WITH OVERNIGHT LOWS BEHIND THE FRONT IN THE 30S AND LOWER 40S...BUT UP TO THE UPPER 50S AHEAD OF THE FRONT. THERE IS STILL A LOW CHANCE FOR DRIZZLE OR VERY LIGHT RAIN OVER THE FAR NORTHEASTERN COUNTIES TONIGHT. FRIDAY THROUGH SATURDAY WILL CONTINUE TO BE COOL BEHIND THE FRONT. WENT WITH THE COOLER GUIDANCE ON SATURDAY ANTICIPATING MOSTLY CLOUDY SKIES AND POSSIBLY SOME ADDITIONAL LIGHT RAIN. THIS CHANCE FOR LIGHT RAIN WILL BE ASSOCIATED WITH A WEAK SHORTWAVE LIFTING NORTHEAST ACROSS THE SOUTHWEST CONUS AND INTO THE PLAINS. THE TRACK OF THIS SHORTWAVE IS SLIGHTLY FARTHER NORTH TONIGHT WITH THE BEST CHANCES FOR RAIN NORTH OF THE REGION. THEREFORE REDUCED POPS TO ONLY 20 PERCENT OF LIGHT RAIN...AND REMOVED THE POPS FROM SUNDAY AS THE SHORTWAVE WILL BE CROSSING OUT OF THE PLAINS BY THEN. AGAIN...ANY PRECIPITATION ON SATURDAY MAY LIKELY ONLY BE DRIZZLE INDUCED BY SOME ISENTROPIC LIFT OVER THE COOL SURFACE LAYER. AFTER SATURDAY...SOUTH TO SOUTHWEST FLOW IN THE LOW TO MID LEVELS OF THE ATMOSPHERE WILL RESULT IN ANOTHER WARM UP. WE WILL SEE TEMPERATURES BACK THE 70S BY MONDAY...WITH BREEZY WINDS AND MOSTLY CLOUDY SKIES. BOTH THE GFS AND ECMWF CONTINUE TO ADVERTISE A STRONGER UPPER LEVEL TROUGH MOVING THROUGH THE PLAINS AROUND THE MIDDLE OF NEXT WEEK...BUT THE LATEST ECMWF SOLUTION HAS CHANGED FROM THE PAST FEW RUNS WITH THE TROUGH NOW FARTHER NORTH AND MUCH BROADER. HOWEVER...IT STILL LOOKS LIKE NORTH AND CENTRAL TEXAS WILL HAVE A CHANCE FOR SHOWERS AND THUNDERSTORMS ON TUESDAY AS A DRYLINE AND COLD FRONT MOVE THROUGH THE REGION. SIDED WITH THE ECMWF IN THE EXTENDED BY CLEARING THE RAIN OUT WITH THE FRONT ON TUESDAY. THE REMAINDER OF THE FORECAST LOOKS DRY AS WE TRANSITION TO NORTHWEST AND/OR MORE ZONAL FLOW FOR A FEW DAYS. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 75 42 56 41 55 / 5 10 5 5 20 WACO, TX 79 53 62 44 62 / 10 10 10 10 20 PARIS, TX 56 39 53 35 53 / 10 20 10 5 20 DENTON, TX 72 40 53 38 53 / 5 10 5 5 20 MCKINNEY, TX 72 40 54 39 53 / 10 10 5 5 20 DALLAS, TX 75 43 57 42 55 / 5 10 5 5 20 TERRELL, TX 74 46 57 41 55 / 10 10 10 5 20 CORSICANA, TX 75 52 61 43 58 / 10 10 10 10 20 TEMPLE, TX 79 54 65 46 64 / 10 5 10 10 20 MINERAL WELLS, TX 73 39 56 39 54 / 5 5 0 5 20 && .FWD WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR TXZ091>095- 102>107-121>123-135-148. && $$ 58/82
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
604 AM CST THU JAN 24 2013 .UPDATE... DESPITE WINDS OF 5 TO 10 MPH...THE FOG HAS BECOME MORE WIDESPREAD THIS MORNING AND WILL UPDATE TO INCLUDE FOG THROUGH THE MID MORNING HOURS. AREAS ALONG THE RED RIVER ARE REPORTING DENSE FOG WHERE THE WINDS HAVE BECOME LIGHT. ELSEWHERE...DENSE FOG IS BEING REPORTED IN ISOLATED AREAS ACROSS THE EASTERN COUNTIES...EAST OF THE HWY 75/I-45 CORRIDORS. WILL ISSUE A DENSE FOG ADVISORY FOR THESE TWO AREAS. 82/JLD && .PREV DISCUSSION... /ISSUED 339 AM CST THU JAN 24 2013/ UPPER LEVEL RIDGE IS NOW CENTERED SOUTHWEST OF THE AREA WITH HIGH CLOUDS STREAMING OVER THE TOP OF THE RIDGE AND INTO THE STATE. AT THE SURFACE...SOME STRATUS CLOUDS ARE NOW DEVELOPING ACROSS SOUTHEAST TEXAS...BUT ARE MOVING TO THE EAST AND NORTHEAST. SOME LOW CLOUDS WILL OCCUR OVER THE SOUTHEASTERN COUNTIES THIS MORNING...BUT SHOULD DISSIPATE BEFORE MIDDAY. IN ADDITION...THERE IS SOME SCATTERED PATCHY OF FOG ASSOCIATED WITH THE LOW CLOUDS IN SOUTHEAST TEXAS. AT THIS TIME DO NOT HAVE FOG MENTIONED IN THE GRIDS AS CURRENT THINKING IS THAT MOST OF THE FOG WILL STAY JUST OUTSIDE OUR AREA...BUT WILL UPDATE IF THE FOG BECOMES MORE WIDESPREAD. WILL ALSO BE MONITORING FOR FOG DEVELOPMENT NEAR THE RED RIVER THIS MORNING AS A COLD FRONT APPROACHES AND THE WINDS BECOME LIGHT. THE COLD FRONT HAS NOW PUSHED INTO SOUTHERN OKLAHOMA WITH TEMPERATURES IN THE 30S AND 40S BEHIND THE FRONT. THIS FRONT WILL EDGE JUST SOUTH OF THE RED RIVER TODAY...RESULTING IN MUCH COOLER TEMPERATURES ACROSS OUR NORTHERN COUNTIES. HIGH TEMPERATURES THIS AFTERNOON WILL RANGE FROM THE UPPER 50S ALONG THE RED RIVER TO NEAR 80 DEGREES IN OUR SOUTHWESTERN COUNTIES. HIGH CLOUDS ACROSS THE REGION AND SOME LOWER LEVEL CLOUDS DEVELOPING BEHIND PARTS OF THE FRONT WILL KEEP TEMPERATURES ON THE COOLER SIDE OF GUIDANCE TODAY. YESTERDAY...IT APPEARED THAT THE FRONT WOULD STALL OR EVEN RETREAT A LITTLE NEAR THE RED RIVER TONIGHT. HOWEVER...HI-RES GUIDANCE INCLUDING THE RAP AND TEXAS TECH WRF ALL SUPPORT THE NAM WHICH BEGINS TO PUSH THE FRONT SOUTH TONIGHT. WITH THE COLD TEMPERATURES THAT ARE ALREADY OCCURRING BEHIND THE FRONT...THIS SOLUTION IS THE MOST PLAUSIBLE ONE AND WILL SHOW THE FRONT SLOWLY MOVING SOUTH AFTER SUNSET. THE FRONT WILL CONTINUE MOVING SOUTH ON FRIDAY...HAVING MADE ITS WAY ALMOST ENTIRELY THROUGH THE CWA BY MIDDAY. TEMPERATURES TONIGHT WILL AGAIN BE VARIABLE WITH OVERNIGHT LOWS BEHIND THE FRONT IN THE 30S AND LOWER 40S...BUT UP TO THE UPPER 50S AHEAD OF THE FRONT. THERE IS STILL A LOW CHANCE FOR DRIZZLE OR VERY LIGHT RAIN OVER THE FAR NORTHEASTERN COUNTIES TONIGHT. FRIDAY THROUGH SATURDAY WILL CONTINUE TO BE COOL BEHIND THE FRONT. WENT WITH THE COOLER GUIDANCE ON SATURDAY ANTICIPATING MOSTLY CLOUDY SKIES AND POSSIBLY SOME ADDITIONAL LIGHT RAIN. THIS CHANCE FOR LIGHT RAIN WILL BE ASSOCIATED WITH A WEAK SHORTWAVE LIFTING NORTHEAST ACROSS THE SOUTHWEST CONUS AND INTO THE PLAINS. THE TRACK OF THIS SHORTWAVE IS SLIGHTLY FARTHER NORTH TONIGHT WITH THE BEST CHANCES FOR RAIN NORTH OF THE REGION. THEREFORE REDUCED POPS TO ONLY 20 PERCENT OF LIGHT RAIN...AND REMOVED THE POPS FROM SUNDAY AS THE SHORTWAVE WILL BE CROSSING OUT OF THE PLAINS BY THEN. AGAIN...ANY PRECIPITATION ON SATURDAY MAY LIKELY ONLY BE DRIZZLE INDUCED BY SOME ISENTROPIC LIFT OVER THE COOL SURFACE LAYER. AFTER SATURDAY...SOUTH TO SOUTHWEST FLOW IN THE LOW TO MID LEVELS OF THE ATMOSPHERE WILL RESULT IN ANOTHER WARM UP. WE WILL SEE TEMPERATURES BACK THE 70S BY MONDAY...WITH BREEZY WINDS AND MOSTLY CLOUDY SKIES. BOTH THE GFS AND ECMWF CONTINUE TO ADVERTISE A STRONGER UPPER LEVEL TROUGH MOVING THROUGH THE PLAINS AROUND THE MIDDLE OF NEXT WEEK...BUT THE LATEST ECMWF SOLUTION HAS CHANGED FROM THE PAST FEW RUNS WITH THE TROUGH NOW FARTHER NORTH AND MUCH BROADER. HOWEVER...IT STILL LOOKS LIKE NORTH AND CENTRAL TEXAS WILL HAVE A CHANCE FOR SHOWERS AND THUNDERSTORMS ON TUESDAY AS A DRYLINE AND COLD FRONT MOVE THROUGH THE REGION. SIDED WITH THE ECMWF IN THE EXTENDED BY CLEARING THE RAIN OUT WITH THE FRONT ON TUESDAY. THE REMAINDER OF THE FORECAST LOOKS DRY AS WE TRANSITION TO NORTHWEST AND/OR MORE ZONAL FLOW FOR A FEW DAYS. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 75 42 56 41 55 / 5 10 5 5 20 WACO, TX 79 53 62 44 62 / 10 10 10 10 20 PARIS, TX 56 39 53 35 53 / 10 20 10 5 20 DENTON, TX 72 40 53 38 53 / 5 10 5 5 20 MCKINNEY, TX 72 40 54 39 53 / 10 10 5 5 20 DALLAS, TX 75 43 57 42 55 / 5 10 5 5 20 TERRELL, TX 74 46 57 41 55 / 10 10 10 5 20 CORSICANA, TX 75 52 61 43 58 / 10 10 10 10 20 TEMPLE, TX 79 54 65 46 64 / 10 5 10 10 20 MINERAL WELLS, TX 73 39 56 39 54 / 5 5 0 5 20 && .FWD WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR TXZ091>095- 102>107-121>123-135-148. && $$ 58/82
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
139 PM CST THU JAN 24 2013 .MESOSCALE DISCUSSION... 955 AM CST THE LAKE EFFECT SNOW ADVISORY FOR LAKE COUNTY INDIANA WILL LIKELY BE CANCELLED SHORTLY AS THE LAKE EFFECT SNOW BAND SHIFTS WESTWARD. MINOR ACCUMULATIONS IN EASTERN COOK COUNTY...ESPECIALLY SOUTHEAST...ARE STILL ON TRACK. VISIBLE SATELLITE AND RADAR MOSAIC TOGETHER SHOW AN IMPRESSIVELY LENGTHY SNOW SHOWER BAND FROM NNE TO SSW ACROSS LAKE MI. WITHIN THIS HAVE BEEN SOME EMBEDDED CIRCULATIONS AS SEEN ON RADAR...AND THESE HAVE BEEN NEAR OR MOVED ONSHORE AND LIKELY BEEN RESPONSIBLE FOR SOME OF THE VERY HEAVY SNOWFALL BURSTS SEEN ON WEBCAMS AND RELAYED TO THE NWS. THE OVERALL CONVERGENCE CONTINUES TO BE STRONG MID-LAKE PER STREAMLINE ANALYSIS AND JUST THE LOOK OF THE CLOUDS ON VISBILE. TOWARD THE NE IL SHORE THIS HAS APPEARED TO WEAKEN SOME...ALTHOUGH THERE ARE STILL SIGNS OF SMALL SCALE CIRCULATIONS IN THE REFLECTIVITY. THE 12Z 850MB AND 925MB TEMPERATURES ARE BOTH AROUND -20C PER MORNING RAOBS AIDING IN SHARP LAPSE RATES OF AIR FROM THE LAKE. A MODIFIED 14Z MDW AMDAR SOUNDING FOR ESTIMATED LAKE TEMPERATURES AND MODIFIED DEW POINTS INDICATING NEARLY 500 J/KG OF LAKE INDUCED CAPE. RAP GUIDANCE SHIFTS AND WEAKENS THE FOCUS OF THE BOUNDARY LAYER CONVERGENCE NORTHWEST DICTATED BY THE AMBIENT FLOW TURNING MORE ESE THIS AFTERNOON. SO THINKING THAT WHILE SNOW SHOWERS MAY NOT BE AS CONCENTRATED INTO COOK AND LAKE COUNTIES IL AS THEY WERE IN NORTHWEST IN EARLIER...THE INSTABILITY WILL HELP TO DRIVE STRONGER SHOWERS AT TIMES. ONE TO TWO INCH AMOUNTS ARE LIKELY IN ANY OF THE LAKESHORE AREAS THAT GET UNDER ONE OF THESE BURSTS EVEN IF FOR JUST A HALF HOUR. MTF && .DISCUSSION... 358 AM CST A LOT GOING ON THROUGH THE NEXT 7 DAYS... TODAY... LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z. HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF PRODUCING SOME ACCUMULATING SNOW. HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED. TONIGHT THROUGH FRIDAY... HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST. GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON. WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT 900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800 MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY NIGHT. SUNDAY THROUGH WEDNESDAY... HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55 RFD. MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH 850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT PERIOD OF SLEET/FREEZING RAIN. 00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN. THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID- LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY... THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF THROUGH THE DAY. FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY. WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING 500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * SNOW DEVELOPING LATE TONIGHT AND CONTINUING INTO FRIDAY MORNING...IFR OR LOWER VIS AND LOW MVFR CIGS POSSIBLE. * GUSTY WEST-NORTHWEST WINDS LATE FRIDAY AFTERNOON/EVENING. KJB //DISCUSSION...UPDATED 18Z... THE REMNANT LAKE EFFECT SNOW SHOWERS ARE CURRENTLY MOVING ACROSS ORD...BUT THE LINE HAS WEAKENED CONSIDERABLY...AND IS NOT RESULTING IN ANY SIGNIFICANT RESTRICTIONS TO THE VISIBILITIES. THIS ACTIVITY WILL QUICKLY MOVE OUT OF THE AREA BY 1 PM THIS AFTERNOON. THE WINDS WILL GRADUALLY BECOME EASTERLY AND THEN SOUTHEASTERLY THROUGH THE AFTERNOON AS HIGH PRESSURE DROPS SOUTHEASTWARD ACROSS LOWER MICHIGAN. OUR NEXT STORM SYSTEM WILL MOVE ACROSS THE REGION LATE TONIGHT AND INTO FRIDAY MORNING. SNOW IS EXPECTED TO DEVELOP AFTER 1 AM NEAR KRFD AND AFTER 3 AM AT THE EASTERN TERMINALS. THERE WILL BE SOME DRY AIR TO OVERCOME INITIALLY. HOWEVER...WITH THE DECENT ISENTROPIC ASCENT AND THE INCREASINGLY SOUTHERLY FLOW...I FEEL THAT THIS DRY AIR WILL BE OVERCOME FAIRLY QUICKLY. MODEL BUFFER SOUNDINGS INDICATE SOME DECENT MID LEVEL LAPSE RATES EARLY FRIDAY MORNING...DURING THE HEIGHT OF THE EVENT. THIS COULD LEAD TO A PERIOD OF SNOW WITH VISIBILITIES POSSIBLY DROPPING DOWN AROUND 1 MILE FOR A FEW HOURS TOMORROW MORNING. THE SNOW SHOULD ABATE LATER IN THE MORNING AS THE MID LEVEL WAVE MOVES EAST OF THE AREA AND DRIER AIR BUILDS INTO THE MID LEVELS. A SURFACE LOW WILL BE MOVING ACROSS THE UPPER GREAT LAKES REGION WITH THE WARM SECTOR BRIEFLY MOVING ACROSS THE AREA FRIDAY EARLY AFTERNOON BEFORE ANOTHER COLD FRONT COMES PUSHING ACROSS THE AREA BY VERY LATE AFTERNOON OR EARLY FRIDAY EVENING. IT IS POSSIBLE THAT SOME ADDITIONAL SNOW SHOWERS COULD DEVELOP DURING THIS TIME AS LOW LEVEL FORCING INCREASES WITH STEEP LOW LEVEL LAPSE RATES. THIS FRONTAL PASSAGE WILL ALSO LEAD TO AN UPTAKE IN THE WIND SPEEDS OUT OF THE WEST NORTHWEST BY EARLY FRIDAY EVENING. KJB //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE IN SNOW WITH MVFR VIS AND CIGS. * MEDIUM CONFIDENCE IN IFR OR LOWER VIS FOR A SHORT PERIOD EARLY FRIDAY MORNING. * LOW CONFIDENCE ON SNOW SHOWERS FRIDAY AFTERNOON. * MEDIUM CONFIDENCE IN GUSTY WINDS FRIDAY LATE AFTERNOON/EVENING. KJB //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...VFR. SATURDAY...VFR. SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS LIKELY. MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH FREEZING RAIN EARLY. MVFR/IFR CONDITIONS LIKELY. TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE. WEDNESDAY...CHANCE LIGHT SNOW SHOWERS. MVFR CONDITIONS POSSIBLE. RODRIGUEZ && .MARINE... 439 AM CST AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO 35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS. EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30 KT WINDS EXPECTED TO PERSIST INTO SATURDAY. RODRIGUEZ && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 PM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1212 PM CST THU JAN 24 2013 .MESOSCALE DISCUSSION... 955 AM CST THE LAKE EFFECT SNOW ADVISORY FOR LAKE COUNTY INDIANA WILL LIKELY BE CANCELLED SHORTLY AS THE LAKE EFFECT SNOW BAND SHIFTS WESTWARD. MINOR ACCUMULATIONS IN EASTERN COOK COUNTY...ESPECIALLY SOUTHEAST...ARE STILL ON TRACK. VISIBLE SATELLITE AND RADAR MOSAIC TOGETHER SHOW AN IMPRESSIVELY LENGTHY SNOW SHOWER BAND FROM NNE TO SSW ACROSS LAKE MI. WITHIN THIS HAVE BEEN SOME EMBEDDED CIRCULATIONS AS SEEN ON RADAR...AND THESE HAVE BEEN NEAR OR MOVED ONSHORE AND LIKELY BEEN RESPONSIBLE FOR SOME OF THE VERY HEAVY SNOWFALL BURSTS SEEN ON WEBCAMS AND RELAYED TO THE NWS. THE OVERALL CONVERGENCE CONTINUES TO BE STRONG MID-LAKE PER STREAMLINE ANALYSIS AND JUST THE LOOK OF THE CLOUDS ON VISBILE. TOWARD THE NE IL SHORE THIS HAS APPEARED TO WEAKEN SOME...ALTHOUGH THERE ARE STILL SIGNS OF SMALL SCALE CIRCULATIONS IN THE REFLECTIVITY. THE 12Z 850MB AND 925MB TEMPERATURES ARE BOTH AROUND -20C PER MORNING RAOBS AIDING IN SHARP LAPSE RATES OF AIR FROM THE LAKE. A MODIFIED 14Z MDW AMDAR SOUNDING FOR ESTIMATED LAKE TEMPERATURES AND MODIFIED DEW POINTS INDICATING NEARLY 500 J/KG OF LAKE INDUCED CAPE. RAP GUIDANCE SHIFTS AND WEAKENS THE FOCUS OF THE BOUNDARY LAYER CONVERGENCE NORTHWEST DICTATED BY THE AMBIENT FLOW TURNING MORE ESE THIS AFTERNOON. SO THINKING THAT WHILE SNOW SHOWERS MAY NOT BE AS CONCENTRATED INTO COOK AND LAKE COUNTIES IL AS THEY WERE IN NORTHWEST IN EARLIER...THE INSTABILITY WILL HELP TO DRIVE STRONGER SHOWERS AT TIMES. ONE TO TWO INCH AMOUNTS ARE LIKELY IN ANY OF THE LAKESHORE AREAS THAT GET UNDER ONE OF THESE BURSTS EVEN IF FOR JUST A HALF HOUR. MTF && .DISCUSSION... 358 AM CST A LOT GOING ON THROUGH THE NEXT 7 DAYS... TODAY... LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z. HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF PRODUCING SOME ACCUMULATING SNOW. HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED. TONIGHT THROUGH FRIDAY... HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST. GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON. WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT 900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800 MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY NIGHT. SUNDAY THROUGH WEDNESDAY... HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55 RFD. MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH 850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT PERIOD OF SLEET/FREEZING RAIN. 00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN. THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID- LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY... THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF THROUGH THE DAY. FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY. WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING 500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * SNOW DEVELOPING LATE TONIGHT AND CONTINUING INTO FRIDAY MORNING...IFR OR LOWER VIS AND LOW MVFR CIGS POSSIBLE. * GUSTY WEST-NORTHWEST WINDS LATE FRIDAY AFTERNOON/EVENING. KJB //DISCUSSION...UPDATED 18Z... THE REMNANT LAKE EFFECT SNOW SHOWERS ARE CURRENTLY MOVING ACROSS ORD...BUT THE LINE HAS WEAKENED CONSIDERABLY...AND IS NOT RESULTING IN ANY SIGNIFICANT RESTRICTIONS TO THE VISIBILITIES. THIS ACTIVITY WILL QUICKLY MOVE OUT OF THE AREA BY 1 PM THIS AFTERNOON. THE WINDS WILL GRADUALLY BECOME EASTERLY AND THEN SOUTHEASTERLY THROUGH THE AFTERNOON AS HIGH PRESSURE DROPS SOUTHEASTWARD ACROSS LOWER MICHIGAN. OUR NEXT STORM SYSTEM WILL MOVE ACROSS THE REGION LATE TONIGHT AND INTO FRIDAY MORNING. SNOW IS EXPECTED TO DEVELOP AFTER 1 AM NEAR KRFD AND AFTER 3 AM AT THE EASTERN TERMINALS. THERE WILL BE SOME DRY AIR TO OVERCOME INITIALLY. HOWEVER...WITH THE DECENT ISENTROPIC ASCENT AND THE INCREASINGLY SOUTHERLY FLOW...I FEEL THAT THIS DRY AIR WILL BE OVERCOME FAIRLY QUICKLY. MODEL BUFFER SOUNDINGS INDICATE SOME DECENT MID LEVEL LAPSE RATES EARLY FRIDAY MORNING...DURING THE HEIGHT OF THE EVENT. THIS COULD LEAD TO A PERIOD OF SNOW WITH VISIBILITIES POSSIBLY DROPPING DOWN AROUND 1 MILE FOR A FEW HOURS TOMORROW MORNING. THE SNOW SHOULD ABATE LATER IN THE MORNING AS THE MID LEVEL WAVE MOVES EAST OF THE AREA AND DRIER AIR BUILDS INTO THE MID LEVELS. A SURFACE LOW WILL BE MOVING ACROSS THE UPPER GREAT LAKES REGION WITH THE WARM SECTOR BRIEFLY MOVING ACROSS THE AREA FRIDAY EARLY AFTERNOON BEFORE ANOTHER COLD FRONT COMES PUSHING ACROSS THE AREA BY VERY LATE AFTERNOON OR EARLY FRIDAY EVENING. IT IS POSSIBLE THAT SOME ADDITIONAL SNOW SHOWERS COULD DEVELOP DURING THIS TIME AS LOW LEVEL FORCING INCREASES WITH STEEP LOW LEVEL LAPSE RATES. THIS FRONTAL PASSAGE WILL ALSO LEAD TO AN UPTAKE IN THE WIND SPEEDS OUT OF THE WEST NORTHWEST BY EARLY FRIDAY EVENING. KJB //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH CONFIDENCE IN SNOW WITH MVFR VIS AND CIGS. * MEDIUM CONFIDENCE IN IFR OR LOWER VIS FOR A SHORT PERIOD EARLY FRIDAY MORNING. * LOW CONFIDENCE ON SNOW SHOWERS FRIDAY AFTERNOON. * MEDIUM CONFIDENCE IN GUSTY WINDS FRIDAY LATE AFTERNOON/EVENING. KJB //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...VFR. SATURDAY...VFR. SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS LIKELY. MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH FREEZING RAIN EARLY. MVFR/IFR CONDITIONS LIKELY. TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE. WEDNESDAY...CHANCE LIGHT SNOW SHOWERS. MVFR CONDITIONS POSSIBLE. RODRIGUEZ && .MARINE... 439 AM CST AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO 35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS. EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30 KT WINDS EXPECTED TO PERSIST INTO SATURDAY. RODRIGUEZ && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 PM THURSDAY. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
1003 AM CST THU JAN 24 2013 .MESOSCALE DISCUSSION... 955 AM CST THE LAKE EFFECT SNOW ADVISORY FOR LAKE COUNTY INDIANA WILL LIKELY BE CANCELLED SHORTLY AS THE LAKE EFFECT SNOW BAND SHIFTS WESTWARD. MINOR ACCUMULATIONS IN EASTERN COOK COUNTY...ESPECIALLY SOUTHEAST...ARE STILL ON TRACK. VISIBLE SATELLITE AND RADAR MOSAIC TOGETHER SHOW AN IMPRESSIVELY LENGTHY SNOW SHOWER BAND FROM NNE TO SSW ACROSS LAKE MI. WITHIN THIS HAVE BEEN SOME EMBEDDED CIRCULATIONS AS SEEN ON RADAR...AND THESE HAVE BEEN NEAR OR MOVED ONSHORE AND LIKELY BEEN RESPONSIBLE FOR SOME OF THE VERY HEAVY SNOWFALL BURSTS SEEN ON WEBCAMS AND RELAYED TO THE NWS. THE OVERALL CONVERGENCE CONTINUES TO BE STRONG MID-LAKE PER STREAMLINE ANALYSIS AND JUST THE LOOK OF THE CLOUDS ON VISBILE. TOWARD THE NE IL SHORE THIS HAS APPEARED TO WEAKEN SOME...ALTHOUGH THERE ARE STILL SIGNS OF SMALL SCALE CIRCULATIONS IN THE REFLECTIVITY. THE 12Z 850MB AND 925MB TEMPERATURES ARE BOTH AROUND -20C PER MORNING RAOBS AIDING IN SHARP LAPSE RATES OF AIR FROM THE LAKE. A MODIFIED 14Z MDW AMDAR SOUNDING FOR ESTIMATED LAKE TEMPERATURES AND MODIFIED DEW POINTS INDICATING NEARLY 500 J/KG OF LAKE INDUCED CAPE. RAP GUIDANCE SHIFTS AND WEAKENS THE FOCUS OF THE BOUNDARY LAYER CONVERGENCE NORTHWEST DICTATED BY THE AMBIENT FLOW TURNING MORE ESE THIS AFTERNOON. SO THINKING THAT WHILE SNOW SHOWERS MAY NOT BE AS CONCENTRATED INTO COOK AND LAKE COUNTIES IL AS THEY WERE IN NORTHWEST IN EARLIER...THE INSTABILITY WILL HELP TO DRIVE STRONGER SHOWERS AT TIMES. ONE TO TWO INCH AMOUNTS ARE LIKELY IN ANY OF THE LAKESHORE AREAS THAT GET UNDER ONE OF THESE BURSTS EVEN IF FOR JUST A HALF HOUR. MTF && .DISCUSSION... 358 AM CST A LOT GOING ON THROUGH THE NEXT 7 DAYS... TODAY... LAKE EFFECT SNOW ADVISORY FOR NORTHWEST INDIANA THROUGH 18Z. HIGHLIGHTS...PERIOD OF SIGNIFICANT LAKE EFFECT THIS MORNING FOR NORTHWEST INDIANA...WITH MULTI-BAND NORTHWEST FLOW TRANSITIONING TO A SINGLE-BAND NORTH FLOW SETUP EARLY. THERMODYNAMIC/WIND PARAMETERS THEN GRADUALLY WEAKEN LATER THIS MORNING/MIDDAY...THOUGH WITH THE BAND LIKELY SHIFTING WEST INTO CHICAGO AND STILL CAPABLE OF PRODUCING SOME ACCUMULATING SNOW. HIGH RES RUNS OF RAP AND OUR LOCALLY RUN WRF CONTINUE TO INDICATE SINGLE BAND NORTH-SOUTH ORIENTED LES PLUME WILL DEVELOP OVER THE NEXT SEVERAL HOURS...BRINGING ADDITIONAL MODERATE/OCCASIONALLY HEAVY SNOW SHOWERS INTO PORTER AND LAKE COUNTIES. CURRENT RADAR MOSAIC FROM AROUND LAKE MICHIGAN DOES INDEED DEPICT BAND DEVELOPING OVER THE EAST PART OF THE LAKE. VEERING OF LOW LEVEL WIND FIELD NOTED IN FORECAST SOUNDINGS DURING THE MORNING/MIDDAY HOURS SHOULD BRING THE BAND WEST OF THE IL/IN STATE LINE...AFFECTING INITIALLY SOUTHEAST COOK LATER THIS MORNING...WITH A SLIGHT WEAKENING OF THERMODYNAMIC PARAMETERS WITH TIME...AND MORE IMPORTANTLY WEAKENING OF THE LOW LEVEL WIND FIELD. WILL MAINTAIN THE LAKE EFFECT SNOW ADVISORY FOR LAKE/PORTER THROUGH THE MORNING AS THEY WILL HAVE THE LONGEST RESIDENCE TIME BENEATH THE MORE ORGANIZED BAND...WITH SOLID 3-6 INCH AMOUNTS STILL LOOKING GOOD THERE. BAND SHOULD BE MORE TRANSITORY AS IT MOVES WEST INTO IL LATER THIS MORNING AND THIS AFTERNOON...WITH PERHAPS 1-3 INCHES CLOSE TO THE LAKE...ESPECIALLY ON THE SOUTHEAST SIDE OF CHICAGO THROUGH MIDDAY. EVEN UP THE SHORE INTO LAKE CO IL WILL PROBABLY SEE SOME WEAKER SNOW SHOWERS AND MINOR ACCUMS OF PERHAPS AN INCH OR TWO IN SOME SPOTS INTO THIS AFTERNOON AS THE LOW LEVEL FLOW CONTINUES TO WEAKEN AND BECOME MORE DISORGANIZED. TONIGHT THROUGH FRIDAY... HIGHLIGHTS...PERIOD OF LIGHT ACCUMULATING SNOW LATE TONIGHT INTO FRIDAY MORNING. 1-3 INCH ACCUMULATIONS EXPECTED...MOSTLY NORTH/EAST. GUIDANCE REMAINS QUITE SIMILAR IN DEPICTING MID-LEVEL SHORT WAVE TROUGH WHICH DROPS SOUTHEAST FROM THE CANADIAN PRAIRIES SOUTHEAST ACROSS THE GREAT LAKES REGION TONIGHT THROUGH FRIDAY AFTERNOON. WHILE THE TRACK OF THE SURFACE LOW PASSES NORTH OF THE CWA...MODEL ISENTROPIC PROGS OF THE 290-300 K SURFACES DEPICT A PERIOD OF FAIRLY STRONG WARM ADVECTION ASCENT FROM LATE THIS EVENING THROUGH EARLY FRIDAY MORNING...WITH A PROGRESSIVE MOISTENING FROM HIGHER LEVELS DOWN TO THE SURFACE. IN ADDITION...FORECAST SOUNDINGS INDICATE THAT THE THERMAL PROFILE PASSES THROUGH TWO FAVORABLE DENDRITIC GROWTH TEMPERATURE LAYERS...ONE AROUND 600 MB AND THE OTHER BETWEEN ABOUT 900-850 MB. THE COMBINATION OF STRONG ISENTROPIC ASCENT AND GOOD OMEGA IN THE DENDRITIC GROWTH LAYER SUGGEST SOME DECENT SNOWFALL RATES ARE POSSIBLE AFTER SATURATION OCCURS LATE TONIGHT/EARLY FRIDAY. GUIDANCE QPF AMOUNTS RANGE FROM 0.10-0.15 INCH LIQUID...THOUGH THE WRF-NAM AND ASSOCIATED WRF-NMM ARE SIGNIFICANTLY LOWER WITH QPF BEING SLOWER TO SATURATE THE COLUMN. SNOW:LIQUID RATIOS IN THE 15-20:1 RANGE INDICATED BY BUFKIT/COBB METHODS...WHICH WOULD PRODUCE 1-3 INCH TOTALS WITH THE HIGHER AMOUNTS MAINLY ACROSS THE NORTH/EAST PARTS OF THE CWA. ISENTROPIC ASCENT DECREASES RAPIDLY BY 15Z FRIDAY MORNING...WITH PRETTY GOOD DRYING OF THE MID/UPPER LEVELS OCCURRING AS WELL. THIS SHOULD SHUT OFF THE WIDESPREAD SNOW BY MID-MORNING OR SO. HOWEVER...SOUNDINGS KEEP THE LAYER BELOW 800 MB FAIRLY MOIST AND WITHIN THE GOOD CRYSTAL GROWTH -10 TO -15 C RANGE WHICH WILL PROBABLY CONTINUE TO SUPPORT SCATTERED FLURRIES/SNOW SHOWERS INTO THE AFTERNOON AS THE MID-LEVEL TROUGH AXIS MOVES THROUGH. SUBSIDENCE ASSOCIATED WITH HEIGHT RISES AND APPROACH OF THE SURFACE HIGH FRIDAY EVENING PORTENDS BLUSTERY...COLDER AND DECREASINGLY CLOUDY CONDITIONS INTO FRIDAY NIGHT. SUNDAY THROUGH WEDNESDAY... HIGHLIGHTS...POTENTIAL FOR PERIOD OF SLEET/FREEZING RAIN LATE SUNDAY/SUNDAY NIGHT...THEN UNSEASONABLY MILD WEATHER WITH POSSIBLE RECORD WARMTH AND POTENTIAL FOR SHOWERS/THUNDER MONDAY NIGHT INTO TUESDAY. RECORD HIGHS FOR TUESDAY/JANUARY 29TH ARE 59 FOR CHI...55 RFD. MEDIUM RANGE GUIDANCE CONTINUES TO SHOW VERY GOOD AGREEMENT WITH THE PATTERN IN DAYS 4-7. LARGE AREA OF SURFACE HIGH PRESSURE MOVES EAST OF THE WESTERN GREAT LAKES REGION SATURDAY NIGHT...AS FLAT UPPER RIDGING DEVELOPS ALOFT IN THE WAKE OF DEPARTING EAST COAST LONG-WAVE TROUGH. ECMWF/GFS/GEM ALL INDICATE A MID-LEVEL SHORT WAVE EJECTING FROM THE DESERT SOUTHWEST BY 12Z SUNDAY...WITH WEAK LEE CYCLOGENESIS DEVELOPING OVER THE CENTRAL HIGH PLAINS. THIS INDUCES SOUTH RETURN FLOW IN THE LOWER LEVELS ACROSS THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY...WITH WARM/MOIST LOW LEVEL ADVECTION EVENTUALLY DEVELOPING ALOFT INTO OUR FORECAST AREA SUNDAY AFTERNOON AND NIGHT ATOP SHALLOW RETREATING COLD AIR MASS. FORECAST SOUNDINGS DEPICT SUB-FREEZING SURFACE TEMPS INITIALLY...WITH WARM NOSE ALOFT INCREASING TO AS MUCH AS +3 TO +6C SUNDAY NIGHT IN THE 900-800 MB LAYER PER IN HIGHER RESOLUTION GFS SOUNDINGS. THIS IS ALSO WELL DEPICTED IN MODEL PARTIAL THICKNESS FIELDS...WITH 1000-850 MB THICKNESS RANGING FROM 1280-1290 METERS IN BOTH ECMWF AND GFS...WITH 850-700 MB THICKNESS VALUES INCREASING TO IN EXCESS OF 1550 METERS OVER THE SOUTHERN 2/3 OR MORE OF THE CWA SUNDAY NIGHT. WITH GUIDANCE PRODUCING 0.20-0.50 INCHES OF LIQUID QPF ACROSS THE CWA SUNDAY AFTERNOON/NIGHT...THIS SUGGESTS THE POTENTIAL FOR A SIGNIFICANT PERIOD OF SLEET/FREEZING RAIN. 00Z GFS/GEM SOLUTIONS BOTH LIFT SURFACE WARM FRONT TOWARD WI BORDER BY 12Z MONDAY MORNING...WHILE THE 00Z ECMWF IS SLIGHTLY FARTHER SOUTH AND HAS TRENDED TOWARD THE GFS/GEM POSITION SINCE ITS 12Z RUN. THIS WOULD SUGGEST THE POTENTIAL FOR SLEET/FREEZING RAIN WOULD THEN DIMINISH MONDAY MORNING AS TEMPS RISE ABOVE FREEZING CWA-WIDE. MID- LEVEL TROUGH AXIS MOVES EAST OF THE AREA BY EARLY MONDAY...WITH LOSS OF STRONGER FORCING AND SOME MID-LEVEL DRYING DEPICTED IN MODEL TIME/HEIGHT SECTIONS. THIS SHOULD ALLOW PRECIP TO TAPER OFF EARLY... THOUGH MODELS DO RETAIN MOIST LOW LEVELS AND SOME VERY LIGHT QPF THROUGH THE DAY. FARTHER TO THE WEST...LONG-WAVE UPPER TROUGH OVER WESTERN CONUS BEGINS TO PUSH EAST BY MONDAY...RESULTING IN SURFACE LOW DEVELOPMENT EAST OF THE ROCKIES. ECMWF/GFS/GEM BEGIN TO DIVERGE A LITTLE WITH EXACT TIMING/PATH OF THE LOW...BUT THE OVERALL CONSENSUS IS THAT IT WILL LIFT NORTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY TUESDAY. WITH THE WFO CHICAGO CWA TO THE SOUTHEAST OF THE LOW TRACK THIS ENABLES THE WARM SECTOR TO SURGE NORTH MONDAY/MONDAY NIGHT...WITH PROGGED SURFACE TEMPERATURES RISING ABOVE FREEZING BY MONDAY EVENING AND ACTUALLY RISING INTO THE 40S MONDAY NIGHT ACROSS MUCH OF THE CWA. VARIOUS MODEL 850 MB TEMPS REACH +8 TO +11 C TUESDAY AHEAD OF THE COLD FRONT...PRESENTING THE POTENTIAL TO WARM WELL INTO THE 50S DEPENDING UPON HOW QUICKLY THE COLD FRONT PUSHES ACROSS THE AREA. IT WILL LIKELY BE RAINY/SHOWERY HOWEVER...AS ALL MODELS INDICATE A MID-LEVEL SHORT WAVE TROUGH LIFTING THROUGH THE EASTERN SIDE OF THE LARGER SCALE LONG-WAVE TROUGH...INCREASING DEEP FORCING FOR ASCENT ABOVE VERY MOIST WARM SECTOR AIR MASS. COULD EVEN BE CONSIDERABLE THUNDER...EVEN SEVERE WEATHER...WITH 12Z GFS SOUNDINGS DEPICTING 500+ J/K OF MLCAPE AND 50-60 KTS OF 0-6 KM BULK SHEAR TUESDAY AFTERNOON. WARMTH WILL BE SHORT-LIVED HOWEVER...AS TEMPS SHOULD SLIDE BACK TOWARD NORMAL WEDNESDAY BEHIND THE COLD FRONT. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * LAKE EFFECT SNOW SHOWERS THROUGH EARLY AFTERNOON...POSSIBLY DROPPING THE VIS UNDER 3 MILES AND DROPPING CIGS UNDER 2000 FT AT MDW AFTER 1645 UTC. * LIGHT SNOW EXPECTED ONCE AGAIN LATE TONIGHT AND EARLY FRIDAY MORNING WITH CEILINGS AND VIS FALLING TO MVFR. RODRIGUEZ/KB //DISCUSSION...UPDATED 16Z... A VERY IMPRESSIVE BAND OF LAKE EFFECT SNOW CONTINUES TO SLOWLY PROGRESS WEST SOUTHWESTWARD TOWARDS CHICAGO. THE MOST INTENSE BAND IS BASICALLY OFFSHORE FROM DOWNTOWN SOUTHWARD TO JUST WEST OF GARY. THE ACTIVITY WITHIN THIS BAND HAS BEEN VERY HEAVY WITH 1/4 OR LESS VIS. THIS BAND SHOULD BEGIN TO WEAKEN OVER THE NEXT HOUR OR TWO AS THE BOUNDARY LAYER FLOW BEGINS TO SHIFT MORE EAST SOUTHEASTWARD. HOWEVER...ENOUGH OF A CONVERGENCE ZONE LOOKS TO REMAIN IN PLACE TO CONTINUE TO SUPPORT LAKE EFFECT SNOW SHOWERS ACROSS THE AREA INTO THE EARLY TO MID AFTERNOON...BEFORE THE ACTIVITY RAPIDLY SHIFTS NORTHWARD. CURRENT TIMING WOULD BRING THE SNOW SHOWERS INTO MDW BY OR JUST PRIOR TO 17 UTC...WITH CONDITIONS LIKELY DROPPING BELOW 5 MILES ON -SNSH. I WILL CONTINUE TO MONITOR OVER THE NEXT 30 MINUTES TO SEE IF LOWER VIS IS JUSTIFIED AT MDW. CONDITIONS REMAIN MORE UNCERTAIN AT ORD AS THE SNOW SHOWERS MAY STRUGGLE TO GET TO FAR INLAND. HOWEVER...I STILL DO THINK THERE IS A DECENT POSSIBILITY THAT ORD WILL SEE SOME -SHSN AFTER 1730 UTC. //DISCUSSION...UPDATED 12Z... QUIET CONDITIONS TO START OFF THE FORECAST PERIOD HERE WITH ONLY HIGH LEVEL CIRRUS OVERHEAD. OF MAIN CONCERN THIS MORNING IS ONGOING LAKE EFFECT SNOW SHOWERS ACROSS NORTHWEST INDIANA...AS THIS SNOW IS EXPECTED TO DRIFT WESTWARD WITH TIME. AS THIS SNOW BAND SHIFTS WEST THIS MORNING IT WILL INITIALLY AFFECT GYY WITH MVFR CEILNGS OF AROUND 2500FT POSSIBLE...AS WELL AS A BRIEF PERIOD OF LIGHT SNOW BRINGING VIS OF 2-3SM. EXPECT THIS BAND TO REMAIN TRANSIENT QUICKLY MOVING WEST. THIS SNOW IS THEN EXPECTED TO MOVE ACROSS NORTHEAST ILLINOIS AFFECTING MDW/ORD BY MID MORNING. ALTHOUGH LIGHT SNOW IS POSSIBLE...IT DOES APPEAR THAT THE HEAVIER SNOW SHOWERS SHOULD STAY JUST TO THE EAST OF THE TERMINALS. NONETHELESS...IT COULD BRING A PERIOD OF MVFR CEILINGS AROUND 2500FT AND VIS TO REMAIN AT AROUND 3-5SM. ONCE AGAIN...THIS MOVING SNOW SHOULD CONTINUE TO PUSH NORTH INTO THE EARLY AFTERNOON WITH SNOW ENDING AS WELL AS OVERALL CONDITIONS IMPROVING. EXPECT ONLY MID LEVEL VFR CEILNGS LATE THIS AFTERNOON AND MOST OF THIS EVENING AS THE NEXT SYSTEM APPROACHES. CEILINGS WILL FALL ONCE AGAIN LATE TONIGHT INTO EARLY FRIDAY MORNING AS LIGHT SNOW/LOWER VIS OVERSPREADS THE TERMINALS AND CONTINUES THROUGH THE REMAINDER OF THE FORECAST PERIOD. RODRIGUEZ //ORD AND MDW CONFIDENCE...UPDATED 16Z... * MEDIUM TO HIGH CONFIDENCE WITH LIGHT SNOW/MVFR VIS/MVFR CEILINGS AT MDW LATER THIS MORNING. LOWER CONFIDENCE AT ORD. * MEDIUM CONFIDENCE WITH LIGHT SNOW AGAIN LATE TONIGHT AND EARLY FRIDAY MORNING. RODRIGUEZ/KB //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...VFR. SATURDAY...VFR. SUNDAY...CHANCE LIGHT SNOW...POSSIBLY MIXING WITH SLEET OR FREEZING RAIN IN THE EVENING AND OVERNIGHT. MVFR/IFR CONDITIONS LIKELY. MONDAY...CHANCE RAIN THROUGH THE DAY...POSSIBLY MIXING WITH FREEZING RAIN EARLY. MVFR/IFR CONDITIONS LIKELY. TUESDAY...CHANCE RAIN. MVFR CONDITIONS POSSIBLE. WEDNESDAY...CHANCE LIGHT SNOW SHOWERS. MVFR CONDITIONS POSSIBLE. RODRIGUEZ && .MARINE... 439 AM CST AS A TROUGH OF LOW PRESSURE CONTINUES TO DEPART TO THE SOUTHEAST AND HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A FAIRLY TIGHT PRESSURE GRADIENT REMAINS OVER THE LAKE THIS MORNING. THIS IS ALLOWING FOR STRONG NORTHERLY WINDS TO PERSIST WITH EVEN GALES TO 35 KT STILL ONGOING OVER THE SOUTHERN END OF THE LAKE. WITH EXPECTED NORTHERLY GALES TO CONTINUE OVER THE NEXT SEVERAL HOURS...EXTENDED THE GALE WARNING FOR THE SOUTHERN HALF OF THE LAKE AND NEARSHORE WATERS IN INDIANA THROUGH MID MORNING. THEN SHOULD OBSERVE A RAPID DIMINISHING TREND AS WINDS ALSO VEER TO THE EAST AND SOUTHEAST TODAY. WITH THIS HIGH PRESSURE QUICK TO PROGRESS THROUGH THE REGION...WINDS WILL PICK UP OUT OF THE SOUTH TONIGHT AS NEW LOW PRESSURE MOVES THROUGH THE NORTHERN PLAINS. EXPECT A PERIOD OF SOUTHERLY WINDS TO 30 KT TONIGHT AND FRIDAY BEFORE WINDS TURN MORE WEST/NORTHWEST LATE IN THE DAY...WITH TO 30 KT WINDS EXPECTED TO PERSIST INTO SATURDAY. RODRIGUEZ && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...LAKE EFFECT SNOW ADVISORY...INZ001 UNTIL NOON THURSDAY. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 PM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
217 PM CST THU JAN 24 2013 ...UPDATE TO LONG TERM... .SYNOPSIS... ISSUED AT 1139 AM CST THU JAN 24 2013 AT 12Z THURSDAY A 500MB TROUGH WAS LOCATED ACROSS WESTERN MONTANA/NORTHERN IDAHO. THIS UPPER LEVEL TROUGH WAS ASSOCIATED WITH A +120KT 250MB JET. EAST OF THIS UPPER LEVEL SYSTEM AT THE 850MB LEVEL A WEDGE OF WARM AIR WAS EVIDENT FROM EASTERN MONTANA SOUTHWARD INTO WYOMING. THE 850MB TEMPERATURE AT GLASGOW, MT AT 12Z THURSDAY WAS +6C. AT THE SURFACE A COLD FRONT EXTENDED FROM EASTERN MONTANA SOUTHWARD ACROSS WYOMING AND EASTERN COLORADO INTO THE PANHANDLE OF TEXAS. NORTHEAST OF THIS FRONT SOME WARM MOIST AIR WAS BEING ADVECTED INTO SOUTHWEST KANSAS AND HAD RESULTED IN WIDESPREAD STATUS. DODGE CITY SOUNDING AT 12Z INDICATED THIS STATUS DECK WAS MAINLY CONFINED TO THE 900MB TO 850MB LEVEL. BELOW THIS STATUS DECK SURFACE TEMPERATURES AS OF 17Z WERE MAINLY IN THE 20S. && .SHORT TERM...(THIS EVENING THROUGH TOMORROW) ISSUED AT 143 PM CST THU JAN 24 2013 12Z NAM AND 12Z GFS VERIFIED FAIRLY WELL AT 18Z WITH THE LOCATION OF AN UPPER LEVEL TROUGH THAT WAS LOCATED OVER WESTERN MONTANA/NORTHERN IDAHO EARLIER THIS MORNING. THE NAM AND GFS REMAINED IN GOOD AGREEMENT MOVING THIS UPPER LEVEL TROUGH ACROSS THE NORTHERN PLAINS DURING THE OVERNIGHT HOURS AND BY EARLY FRIDAY MORNING PLACED THIS UPPER TROUGH OVER THE WESTERN GREAT LAKES REGION. AS THIS SYSTEM CROSSES THE NORTHERN PLAINS OVERNIGHT, A COLD FRONT WILL DROP SOUTH TOWARDS THE CENTRAL PLAINS. AS THIS FRONT APPROACHES KANSAS EARLY TONIGHT...A WEDGE OF WARMER AIR IN THE LOWER LEVELS THAT WAS LOCATED AHEAD OF THIS COLD FRONT OVER EASTERN WYOMING/MONTANA AT 12Z THURSDAY WILL DROP SOUTHEAST INTO WESTERN KANSAS. GIVEN THIS WARMER AIR SPREADING INTO THE AREA OVERNIGHT ALONG WITH MOSTLY CLOUDY SKIES, IT STILL APPEARS THE PREVIOUS FORECAST IS ON TRACK KEEPING THE DIURNAL CHANGE IN TEMPERATURES BETWEEN EARLIER TODAY AND OVERNIGHT SMALL. BASED ON EXPECTED HIGHS TODAY WILL FAVOR OVERNIGHT LOWS MAINLY IN THE LOW TO MID 20S. ON FRIDAY AN UPPER LEVEL RIDGE AXIS WILL BUILD ACROSS THE ROCKIES AS THE UPPER LEVEL TROUGH CROSSES THE GREAT LAKES AND OHIO VALLEY. 850MB TEMPERATURES FRIDAY AFTERNOON ARE FORECAST TO RANGE FROM +4C TO +6C. 925MB TEMPERATURES WILL AVERAGE BETWEEN +8 AND +12C. USING THESE AS A GUIDE FOR HIGHS FRIDAY AFTERNOON IT WOULD APPEAR TEMPERATURES SHOULD REBOUND BACK AT LEAST INTO THE LOWER 50S. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 208 PM CST THU JAN 24 2013 MEDIUM RANGE MODELS CONTINUE TO INDICATE AN UPPER LEVEL TROUGH OF LOW PRESSURE PUSHING ASHORE INTO SOUTHERN CALIFORNIA LATE FRIDAY NIGHT THEN LIFTING NORTHEASTWARD ACROSS THE CENTRAL AND SOUTHERN ROCKIES SATURDAY. THIS WILL BRING THE NEXT CHANCE FOR PRECIP TO CENTRAL AND PORTIONS OF WESTERN KANSAS SATURDAY EVENING INTO EARLY SUNDAY. A DEVELOPING SOUTH TO SOUTHEASTERLY LOW LEVEL FLOW WILL ADVECT SOME INCREASED MOISTURE NORTHWARD INTO WESTERN KANSAS WITH H85 DEWPOINTS CLIMBING ABOVE 0C LATE SATURDAY AFTERNOON. INCREASED DIVERGENCE ALOFT COMBINED WITH A MODEST +70KT UPPER LEVEL JET WILL PROVIDE ENOUGH FAVORABLE DYNAMIC SUPPORT TO SUPPORT PRECIP DEVELOPMENT FROM THE SOUTH PLAINS OF THE TEXAS PANHANDLE AND WESTERN OKLAHOMA NORTHEAST INTO KANSAS. GFS AND ECMWF MODEL SOUNDINGS SHOW A LACK OF INSTABILITY WITH ENVIRONMENTAL PROFILES REMAINING ABOVE FREEZING GENERALLY BELOW H7 SUGGESTING A LIGHT TO MODERATE RAIN EVENT, PARTICULARLY WITH LOW QPF AND PW VALUES OF LESS THAN ONE INCH. ANY PRECIP WILL COME TO AN END WEST TO EAST BY LATE SUNDAY AFTERNOON. DRIER CONDITIONS ARE THEN EXPECTED INTO THE EARLY PART OF NEXT WEEK AS A DEEP UPPER LEVEL TROUGH BEGINS TO DIG SOUTHEAST ACROSS THE FAR WESTERN CONUS. THIS SYSTEM COULD PROVIDE SOME CHANCE FOR PRECIP ACROSS THE WESTERN HIGH PLAINS IN THE TUESDAY/WEDNESDAY TIME FRAME. ABOVE NORMAL TEMPERATURES ARE EXPECTED SATURDAY AS SURFACE TROUGHING IN EASTERN COLORADO CONTINUES TO HELP INFLUENCE A LOW LEVEL SOUTHERLY FLOW INTO WESTERN KANSAS. THIS WILL DRAW SLIGHTLY WARMER AIR FURTHER NORTH INTO WESTERN KANSAS WITH THE GEM, GFS, AND ECMWF SHOWING H85 TEMPERATURES RANGING FROM THE MID SINGLE DIGITS(C) ACROSS CENTRAL KANSAS TO NEAR 10C CLOSE TO THE COLORADO BORDER. COMBINED WITH DECREASING CLOUDS, LOOK FOR WIDESPREAD 50S(F) ACROSS SOUTHWEST KANSAS WITH NEAR 60F POSSIBLE IN EXTREME SOUTHWEST KANSAS. THE SURFACE TROUGH IS PROJECTED TO EDGE SLOWLY EAST INTO FAR WESTERN KANSAS SUNDAY INFLUENCING MORE OF A WEST TO SOUTHWESTERLY DOWNSLOPE FLOW ACROSS WESTERN KANSAS LEADING TO EVEN WARMER TEMPERATURES SUNDAY AFTERNOON. EXPECT HIGHS WELL UP INTO THE 50S(F) WITH LOWER TO MID 60S(F) POSSIBLE ALONG THE OKLAHOMA BORDER IN FAR SOUTHWEST KANSAS. THE WARMING TREND WILL CONTINUE INTO MONDAY AS ANOTHER SURFACE LOW DEVELOPS LEE OF THE ROCKIES IN ADVANCE OF A STRONG UPPER LEVEL TROUGH APPROACHING FROM THE WEST. WIDESPREAD 60S(F) ARE LIKELY MONDAY AFTERNOON WITH NEAR 70F A POSSIBILITY IN SOME LOCATIONS. A SURGE OF COLD AIR BEHIND A FRONTAL PASSAGE WILL LOWER HIGH TEMPERATURES TUESDAY THROUGH THE END OF THE PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1139 AM CST THU JAN 24 2013 12Z BUFR SOUNDINGS SUGGESTING MVFR STATUS DECK WILL LINGER ACROSS ALL THE TAF SITES THROUGH AT LEAST THE LATE AFTERNOON. HRRR WAS A LITTLE MORE PESSIMISTIC KEEPING THE STATUS IN AT GCK UNTIL AROUND 00Z. AT THIS TIME GIVEN THE LATEST SATELLITE LOOP WHICH SUGGESTED SOME MID-HIGH LEVEL MOISTURE WAS ALREADY BEGINNING TO SPREAD INTO WESTERN KANSAS LATE THIS MORNING HAVE DECIDED TO FOLLOW THE SLOWER EROSION OF THE MVFR CIGS. AS A RESULT EXPECT CIGS TO REMAIN AS IS UNTIL 00Z FRIDAY AT GCK, 03Z AT DDC AND HYS. EASTERLY SURFACE WINDS AT 10KTS OR LESS WILL GRADUALLY SHIFT TO THE SOUTH/SOUTHWEST BY LATE DAY. && .PRELIMINARY POINT TEMPS/POPS... DDC 23 53 27 55 / 0 0 0 10 GCK 23 53 28 57 / 0 0 0 10 EHA 28 54 32 58 / 0 0 0 10 LBL 25 54 29 57 / 0 0 0 10 HYS 21 52 26 54 / 0 0 0 0 P28 23 55 26 54 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BURGERT SHORT TERM...BURGERT LONG TERM...JJOHNSON AVIATION...BURGERT
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
146 PM CST THU JAN 24 2013 ...UPDATED SHORT TERM DISCUSSION... .SYNOPSIS... ISSUED AT 1139 AM CST THU JAN 24 2013 AT 12Z THURSDAY A 500MB TROUGH WAS LOCATED ACROSS WESTERN MONTANA/NORTHERN IDAHO. THIS UPPER LEVEL TROUGH WAS ASSOCIATED WITH A +120KT 250MB JET. EAST OF THIS UPPER LEVEL SYSTEM AT THE 850MB LEVEL A WEDGE OF WARM AIR WAS EVIDENT FROM EASTERN MONTANA SOUTHWARD INTO WYOMING. THE 850MB TEMPERATURE AT GLASGOW, MT AT 12Z THURSDAY WAS +6C. AT THE SURFACE A COLD FRONT EXTENDED FROM EASTERN MONTANA SOUTHWARD ACROSS WYOMING AND EASTERN COLORADO INTO THE PANHANDLE OF TEXAS. NORTHEAST OF THIS FRONT SOME WARM MOIST AIR WAS BEING ADVECTED INTO SOUTHWEST KANSAS AND HAD RESULTED IN WIDESPREAD STATUS. DODGE CITY SOUNDING AT 12Z INDICATED THIS STATUS DECK WAS MAINLY CONFINED TO THE 900MB TO 850MB LEVEL. BELOW THIS STATUS DECK SURFACE TEMPERATURES AS OF 17Z WERE MAINLY IN THE 20S. && .SHORT TERM...(THIS EVENING THROUGH TOMORROW) ISSUED AT 143 PM CST THU JAN 24 2013 12Z NAM AND 12Z GFS VERIFIED FAIRLY WELL AT 18Z WITH THE LOCATION OF AN UPPER LEVEL TROUGH THAT WAS LOCATED OVER WESTERN MONTANA/NORTHERN IDAHO EARLIER THIS MORNING. THE NAM AND GFS REMAINED IN GOOD AGREEMENT MOVING THIS UPPER LEVEL TROUGH ACROSS THE NORTHERN PLAINS DURING THE OVERNIGHT HOURS AND BY EARLY FRIDAY MORNING PLACED THIS UPPER TROUGH OVER THE WESTERN GREAT LAKES REGION. AS THIS SYSTEM CROSSES THE NORTHERN PLAINS OVERNIGHT, A COLD FRONT WILL DROP SOUTH TOWARDS THE CENTRAL PLAINS. AS THIS FRONT APPROACHES KANSAS EARLY TONIGHT...A WEDGE OF WARMER AIR IN THE LOWER LEVELS THAT WAS LOCATED AHEAD OF THIS COLD FRONT OVER EASTERN WYOMING/MONTANA AT 12Z THURSDAY WILL DROP SOUTHEAST INTO WESTERN KANSAS. GIVEN THIS WARMER AIR SPREADING INTO THE AREA OVERNIGHT ALONG WITH MOSTLY CLOUDY SKIES, IT STILL APPEARS THE PREVIOUS FORECAST IS ON TRACK KEEPING THE DIURNAL CHANGE IN TEMPERATURES BETWEEN EARLIER TODAY AND OVERNIGHT SMALL. BASED ON EXPECTED HIGHS TODAY WILL FAVOR OVERNIGHT LOWS MAINLY IN THE LOW TO MID 20S. ON FRIDAY AN UPPER LEVEL RIDGE AXIS WILL BUILD ACROSS THE ROCKIES AS THE UPPER LEVEL TROUGH CROSSES THE GREAT LAKES AND OHIO VALLEY. 850MB TEMPERATURES FRIDAY AFTERNOON ARE FORECAST TO RANGE FROM +4C TO +6C. 925MB TEMPERATURES WILL AVERAGE BETWEEN +8 AND +12C. USING THESE AS A GUIDE FOR HIGHS FRIDAY AFTERNOON IT WOULD APPEAR TEMPERATURES SHOULD REBOUND BACK AT LEAST INTO THE LOWER 50S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 330 AM CST THU JAN 24 2013 FRIDAY WILL START WITH THE UPPER LEVEL FLOW OVER KANSAS IN A SLIGHT DOWNSLOPE PATTERN WITH NORTHWEST FLOW ALOFT. SKIES SHOULD START OUT FRIDAY MORNING SUNNY, WITH LIGHT NORTH TO NORTHWEST SURFACE WINDS. BY FRIDAY AFTERNOON, A FEW HIGH CIRRUS CLOUDS WILL STREAM IN WITH SKIES BECOMING MOSTLY SUNNY, AND WINDS SHIFTING TO THE SOUTH AT 10 MPH OR LESS. CLOUDS WILL CONTINUE TO INCREASE FRIDAY NIGHT. WINDS WILL REMAIN SOUTH AT AROUND 10 MPH, SO MINIMUM TEMPS WILL BE MILD IN THE MID 20S TO LOWER 30S. ON SATURDAY, AN UPPER LEVEL WAVE WILL BE APPROACHING FROM THE SOUTHWEST. PLENTY OF MOISTURE IS STILL SITTING OVER TEXAS AND WILL STILL BE THERE SATURDAY. THE DEEP, SOUTHWEST FLOW ALOFT WILL ADVECT SOME OF THAT MOISTURE NORTH INTO KANSAS. WHEN THAT UPPER WAVE APPROACHES LATE SATURDAY, THE MOISTURE WILL BE IN PLACE. THERE ARE SLIGHT CHANCES FOR RAIN IN OUR EAST VERY LATE ON SATURDAY, BUT PRECIPITATION CHANCES WILL INCREASE SATURDAY NIGHT AS THE UPPER LIFT MOVES IN. PRECIPITATION CHANCES WILL BE AS HIGH AS 50 PERCENT IN OUR EAST AND SOUTHEAST, BASICALLY EAST OF HIGHWAY 19. AS FOR PRECIPITATION, RAIN WILL DOMINATE, AND RAINFALL AMOUNTS WILL BE ON THE LIGHT SIDE. THE GFS MODEL HAS THE MOST PRECIP, WITH 0.25 IN OUR EAST, BUT THE GEM AND THE ECMWF MODELS BOTH PRODUCE LESS THAN A TENTH OF AN INCH OF RAINFALL SATURDAY AND SUNDAY MORNING. SUNDAY, PRECIP CHANCES WILL JUST BE ACROSS OUR EXTREME EASTERN TIER OF COUNTIES, FROM ELLIS SOUTH TO BARBER COUNTY. AFTER THIS WAVE PASSES SUNDAY, THE UPPER PATTERN WILL TURN TO THE SOUTHWEST, WITH A WARMING TREND. BY TUESDAY, MAX TEMPS SHOULD BE WELL INTO THE MID 50S NORTH OF I-70 TO THE MID 60S SOUTH ALONG THE OKLAHOMA BORDER. A LARGE, BROAD SCALE UPPER TROUGH WILL BE MOVING INTO THE PLAINS TUESDAY INTO WEDNESDAY, AND A LOW END SLIGHT CHANCE FOR RAIN WILL EXIST OVER OUR NORTHERN MOST COUNTIES OF ELLIS AND TREGO. I AM NOT TOO CONFIDENT IN THESE PRECIPITATION CHANCES TUESDAY AND WEDNESDAY, SO STAYED WITH LOW 15-16 PERCENT CHANCES ONLY, FOR NOW. FOR MOST OF THIS EXTENDED FORECAST, THE ECMWF MODEL WAS FAVORED. THE GFS SEEMS TOO WET AND SLOWER WITH THE UPPER PROGRESSION OF WAVES. THE GEM CANADIAN MODEL ON THE OTHER HAND IS FASTER AND LESS WET. THUS, THE ECMWF IS A GOOD COMPROMISE. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1139 AM CST THU JAN 24 2013 12Z BUFR SOUNDINGS SUGGESTING MVFR STATUS DECK WILL LINGER ACROSS ALL THE TAF SITES THROUGH AT LEAST THE LATE AFTERNOON. HRRR WAS A LITTLE MORE PESSIMISTIC KEEPING THE STATUS IN AT GCK UNTIL AROUND 00Z. AT THIS TIME GIVEN THE LATEST SATELLITE LOOP WHICH SUGGESTED SOME MID-HIGH LEVEL MOISTURE WAS ALREADY BEGINNING TO SPREAD INTO WESTERN KANSAS LATE THIS MORNING HAVE DECIDED TO FOLLOW THE SLOWER EROSION OF THE MVFR CIGS. AS A RESULT EXPECT CIGS TO REMAIN AS IS UNTIL 00Z FRIDAY AT GCK, 03Z AT DDC AND HYS. EASTERLY SURFACE WINDS AT 10KTS OR LESS WILL GRADUALLY SHIFT TO THE SOUTH/SOUTHWEST BY LATE DAY. && .PRELIMINARY POINT TEMPS/POPS... DDC 23 53 27 53 / 0 0 0 10 GCK 23 53 28 54 / 0 0 0 10 EHA 28 54 32 57 / 0 0 0 10 LBL 25 54 29 56 / 0 0 0 10 HYS 21 52 26 48 / 0 0 0 0 P28 23 55 26 49 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BURGERT SHORT TERM...BURGERT LONG TERM...BURKE AVIATION...BURGERT
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1224 PM CST THU JAN 24 2013 ...UPDATED THIS AFTERNOON PERIOD TO LOWER MAX TEMPERATURES... .SYNOPSIS... ISSUED AT 1139 AM CST THU JAN 24 2013 AT 12Z THURSDAY A 500MB TROUGH WAS LOCATED ACROSS WESTERN MONTANA/NORTHERN IDAHO. THIS UPPER LEVEL TROUGH WAS ASSOCIATED WITH A +120KT 250MB JET. EAST OF THIS UPPER LEVEL SYSTEM AT THE 850MB LEVEL A WEDGE OF WARM AIR WAS EVIDENT FROM EASTERN MONTANA SOUTHWARD INTO WYOMING. THE 850MB TEMPERATURE AT GLASGOW, MT AT 12Z THURSDAY WAS +6C. AT THE SURFACE A COLD FRONT EXTENDED FROM EASTERN MONTANA SOUTHWARD ACROSS WYOMING AND EASTERN COLORADO INTO THE PANHANDLE OF TEXAS. JUST NORTH OF THIS FRONT SOME WARM MOIST AIR WAS BEING ADVECTED INTO SOUTHWEST KANSAS AND HAD RESULTED IN WIDESPREAD STATUS. DODGE CITY SOUNDING AT 12Z INDICATED THIS STATUS DECK WAS MAINLY CONFINED TO THE 900MB TO 850MB LEVEL. BELOW THIS STATUS DECK SURFACE TEMPERATURES AS OF 17Z WERE MAINLY IN THE 20S. && .UPDATE... ISSUED AT 1211 PM CST THU JAN 24 2013 LOW STATUS DECK ACROSS WESTERN KANSAS HAS BEEN SLOW TO ERODE EARLIER THIS MORNING. BASED ON 17Z VISIBLE SATELLITE LOOP SOME HIGHER LEVEL CLOUDS NOW APPEAR TO BE SPREADING INTO WESTERN KANSAS OVER THIS LINGERING LOW STATUS DECK. 12Z NAM BUFR SOUNDINGS DOES SUGGEST CLEARING IN THE WEST AFTER 3 PM, HOWEVER THE 14Z AND 15Z RAPID REFRESH MODEL APPEARS TO BE MORE SLOWER WITH THE EROSION OF THESE LOW CLOUDS. GIVEN THE HIGHER LEVEL CLOUD COVER THAT WERE ALREADY BEGINNING TO SPREAD ACROSS WESTERN KANSAS HAVE FAVOR THE RAPID REFRESH MODEL IN KEEPING CLOUDS IN LONGER. AS A RESULT HAVE LOWERED AFTERNOON TEMPERATURES ACROSS WESTERN KANSAS. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 347 AM CST THU JAN 24 2013 A SHORTWAVE TROUGH WAS MOVING SOUTHEAST INTO THE GREAT LAKES REGION THIS MORNING AND COLD HIGH PRESSURE WAS PUSHING SOUTH IN ITS WAKE. THE WESTERN EDGE OF THIS COLD AIR WAS MOVING INTO SOUTHWEST KANSAS IN UPSLOPE FASHION FROM THE NORTHEAST. MEANWHILE, THE NEXT SHORTWAVE TROUGH WAS PROGRESSING ACROSS THE PACIFIC NORTHWEST EARLY THIS MORNING. THIS SYSTEM WILL APPROACH THE NORTHERN HIGH PLAINS BY THIS AFTERNOON AND RESULT IN SURFACE TROUGHING IN THE LEE OF THE NORTHERN ROCKIES. IF THIS SYSTEM WAS FASTER, THE ASSOCIATED PACIFIC COLD FRONT WOULD HAVE NO PROBLEM SCOURING THE SHALLOW COLD AIR OUT OF WESTERN KANSAS. HOWEVER, IT APPEARS THAT THE COLD FRONTAL PASSAGE WILL HOLD OFF UNTIL LATER TONIGHT. ALSO, THE LEE TROUGH AND ASSOCIATED SOUTHERLY WINDS AHEAD OF THE SYSTEM ARE NOT ADVERTISED TO BE STRONG ENOUGH TO SCOUR OUT THE COLD AIR. INSTEAD, THE ISENTROPIC LIFT WITH THE DEVELOPING SOUTHERLIES WILL AID IN LOW CLOUD DEVELOPMENT THIS MORNING AND A WEAK UPSLOPE COMPONENT WILL PERSIST AT LOWER LEVELS THROUGH THE DAY. THE NAM SOUNDINGS SHOW A SHALLOW LAYER OF SATURATION ABOVE 900MB AND THIS IS REASONABLE BASED ON THE HIGHER OBSERVED SURFACE DEWPOINTS CURRENTLY RESIDING ACROSS OKLAHOMA. ALSO, PLENTY OF HIGH LEVEL CLOUD WAS PRESENT ACROSS KANSAS THIS MORNING AND SHOULD PERSIST THROUGH THE DAY AND FURTHER LIMIT INSOLATION. THEREFORE, TEMPERATURES FROM DODGE CITY EASTWARD WILL STAY AT OR BELOW FREEZING. SOME COLD AIR EROSION IS EXPECTED IN FAR WESTERN KANSAS WHERE TEMPERATURES COULD REACH INTO THE UPPER 30S AND 40S. THE OFFICIAL FORECAST WILL BE A FEW DEGREES COLDER THAN THE NAM. FOR SOME REASON THE RAP ERODES THE COLD AIR WITH HIGHS IN THE MID 40S EVEN AS FAR EAST AS DODGE CITY. BY TONIGHT, THE LOW LEVEL WINDS ARE EXPECTED TO VEER TO THE SOUTHWEST AS THE AFOREMENTIONED PACIFIC COLD FRONT APPROACHES. THUS THE LOW CLOUDS WILL RAPIDLY CLEAR OUT. TEMPERATURES WILL INITIALLY FALL INTO THE 20S OVERNIGHT BUT THEN HOLD STEADY OR EVEN RISE AFTER 3 AM AS VERTICAL MIXING INCREASES BEHIND THE PACIFIC COLD FRONT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 330 AM CST THU JAN 24 2013 FRIDAY WILL START WITH THE UPPER LEVEL FLOW OVER KANSAS IN A SLIGHT DOWNSLOPE PATTERN WITH NORTHWEST FLOW ALOFT. SKIES SHOULD START OUT FRIDAY MORNING SUNNY, WITH LIGHT NORTH TO NORTHWEST SURFACE WINDS. BY FRIDAY AFTERNOON, A FEW HIGH CIRRUS CLOUDS WILL STREAM IN WITH SKIES BECOMING MOSTLY SUNNY, AND WINDS SHIFTING TO THE SOUTH AT 10 MPH OR LESS. CLOUDS WILL CONTINUE TO INCREASE FRIDAY NIGHT. WINDS WILL REMAIN SOUTH AT AROUND 10 MPH, SO MINIMUM TEMPS WILL BE MILD IN THE MID 20S TO LOWER 30S. ON SATURDAY, AN UPPER LEVEL WAVE WILL BE APPROACHING FROM THE SOUTHWEST. PLENTY OF MOISTURE IS STILL SITTING OVER TEXAS AND WILL STILL BE THERE SATURDAY. THE DEEP, SOUTHWEST FLOW ALOFT WILL ADVECT SOME OF THAT MOISTURE NORTH INTO KANSAS. WHEN THAT UPPER WAVE APPROACHES LATE SATURDAY, THE MOISTURE WILL BE IN PLACE. THERE ARE SLIGHT CHANCES FOR RAIN IN OUR EAST VERY LATE ON SATURDAY, BUT PRECIPITATION CHANCES WILL INCREASE SATURDAY NIGHT AS THE UPPER LIFT MOVES IN. PRECIPITATION CHANCES WILL BE AS HIGH AS 50 PERCENT IN OUR EAST AND SOUTHEAST, BASICALLY EAST OF HIGHWAY 19. AS FOR PRECIPITATION, RAIN WILL DOMINATE, AND RAINFALL AMOUNTS WILL BE ON THE LIGHT SIDE. THE GFS MODEL HAS THE MOST PRECIP, WITH 0.25 IN OUR EAST, BUT THE GEM AND THE ECMWF MODELS BOTH PRODUCE LESS THAN A TENTH OF AN INCH OF RAINFALL SATURDAY AND SUNDAY MORNING. SUNDAY, PRECIP CHANCES WILL JUST BE ACROSS OUR EXTREME EASTERN TIER OF COUNTIES, FROM ELLIS SOUTH TO BARBER COUNTY. AFTER THIS WAVE PASSES SUNDAY, THE UPPER PATTERN WILL TURN TO THE SOUTHWEST, WITH A WARMING TREND. BY TUESDAY, MAX TEMPS SHOULD BE WELL INTO THE MID 50S NORTH OF I-70 TO THE MID 60S SOUTH ALONG THE OKLAHOMA BORDER. A LARGE, BROAD SCALE UPPER TROUGH WILL BE MOVING INTO THE PLAINS TUESDAY INTO WEDNESDAY, AND A LOW END SLIGHT CHANCE FOR RAIN WILL EXIST OVER OUR NORTHERN MOST COUNTIES OF ELLIS AND TREGO. I AM NOT TOO CONFIDENT IN THESE PRECIPITATION CHANCES TUESDAY AND WEDNESDAY, SO STAYED WITH LOW 15-16 PERCENT CHANCES ONLY, FOR NOW. FOR MOST OF THIS EXTENDED FORECAST, THE ECMWF MODEL WAS FAVORED. THE GFS SEEMS TOO WET AND SLOWER WITH THE UPPER PROGRESSION OF WAVES. THE GEM CANADIAN MODEL ON THE OTHER HAND IS FASTER AND LESS WET. THUS, THE ECMWF IS A GOOD COMPROMISE. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1139 AM CST THU JAN 24 2013 12Z BUFR SOUNDINGS SUGGESTING MVFR STATUS DECK WILL LINGER ACROSS ALL THE TAF SITES THROUGH AT LEAST THE LATE AFTERNOON. HRRR WAS A LITTLE MORE PESSIMISTIC KEEPING THE STATUS IN AT GCK UNTIL AROUND 00Z. AT THIS TIME GIVEN THE LATEST SATELLITE LOOP WHICH SUGGESTED SOME MID-HIGH LEVEL MOISTURE WAS ALREADY BEGINNING TO SPREAD INTO WESTERN KANSAS LATE THIS MORNING HAVE DECIDED TO FOLLOW THE SLOWER EROSION OF THE MVFR CIGS. AS A RESULT EXPECT CIGS TO REMAIN AS IS UNTIL 00Z FRIDAY AT GCK, 03Z AT DDC AND HYS. EASTERLY SURFACE WINDS AT 10KTS OR LESS WILL GRADUALLY SHIFT TO THE SOUTH/SOUTHWEST BY LATE DAY. && .PRELIMINARY POINT TEMPS/POPS... DDC 25 52 27 53 / 0 0 0 20 GCK 25 52 28 54 / 0 0 0 10 EHA 27 53 32 57 / 0 0 0 10 LBL 26 53 29 56 / 0 0 0 10 HYS 22 50 26 48 / 0 0 0 20 P28 27 53 26 49 / 0 0 0 20 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...BURGERT SYNOPSIS...BURGERT SHORT TERM...FINCH LONG TERM...BURKE AVIATION...BURGERT
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1141 AM CST THU JAN 24 2013 ...UPDATED SYNOPSIS AND AVIATION DISCUSSION... .SYNOPSIS... ISSUED AT 1139 AM CST THU JAN 24 2013 AT 12Z THURSDAY A 500MB TROUGH WAS LOCATED ACROSS WESTERN MONTANA/NORTHERN IDAHO. THIS UPPER LEVEL TROUGH WAS ASSOCIATED WITH A +120KT 250MB JET. EAST OF THIS UPPER LEVEL SYSTEM AT THE 850MB LEVEL A WEDGE OF WARM AIR WAS EVIDENT FROM EASTERN MONTANA SOUTHWARD INTO WYOMING. THE 850MB TEMPERATURE AT GLASGOW, MT AT 12Z THURSDAY WAS +6C. AT THE SURFACE A COLD FRONT EXTENDED FROM EASTERN MONTANA SOUTHWARD ACROSS WYOMING AND EASTERN COLORADO INTO THE PANHANDLE OF TEXAS. JUST NORTH OF THIS FRONT SOME WARM MOIST AIR WAS BEING ADVECTED INTO SOUTHWEST KANSAS AND HAD RESULTED IN WIDESPREAD STATUS. DODGE CITY SOUNDING AT 12Z INDICATED THIS STATUS DECK WAS MAINLY CONFINED TO THE 900MB TO 850MB LEVEL. BELOW THIS STATUS DECK SURFACE TEMPERATURES AS OF 17Z WERE MAINLY IN THE 20S. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 347 AM CST THU JAN 24 2013 A SHORTWAVE TROUGH WAS MOVING SOUTHEAST INTO THE GREAT LAKES REGION THIS MORNING AND COLD HIGH PRESSURE WAS PUSHING SOUTH IN ITS WAKE. THE WESTERN EDGE OF THIS COLD AIR WAS MOVING INTO SOUTHWEST KANSAS IN UPSLOPE FASHION FROM THE NORTHEAST. MEANWHILE, THE NEXT SHORTWAVE TROUGH WAS PROGRESSING ACROSS THE PACIFIC NORTHWEST EARLY THIS MORNING. THIS SYSTEM WILL APPROACH THE NORTHERN HIGH PLAINS BY THIS AFTERNOON AND RESULT IN SURFACE TROUGHING IN THE LEE OF THE NORTHERN ROCKIES. IF THIS SYSTEM WAS FASTER, THE ASSOCIATED PACIFIC COLD FRONT WOULD HAVE NO PROBLEM SCOURING THE SHALLOW COLD AIR OUT OF WESTERN KANSAS. HOWEVER, IT APPEARS THAT THE COLD FRONTAL PASSAGE WILL HOLD OFF UNTIL LATER TONIGHT. ALSO, THE LEE TROUGH AND ASSOCIATED SOUTHERLY WINDS AHEAD OF THE SYSTEM ARE NOT ADVERTISED TO BE STRONG ENOUGH TO SCOUR OUT THE COLD AIR. INSTEAD, THE ISENTROPIC LIFT WITH THE DEVELOPING SOUTHERLIES WILL AID IN LOW CLOUD DEVELOPMENT THIS MORNING AND A WEAK UPSLOPE COMPONENT WILL PERSIST AT LOWER LEVELS THROUGH THE DAY. THE NAM SOUNDINGS SHOW A SHALLOW LAYER OF SATURATION ABOVE 900MB AND THIS IS REASONABLE BASED ON THE HIGHER OBSERVED SURFACE DEWPOINTS CURRENTLY RESIDING ACROSS OKLAHOMA. ALSO, PLENTY OF HIGH LEVEL CLOUD WAS PRESENT ACROSS KANSAS THIS MORNING AND SHOULD PERSIST THROUGH THE DAY AND FURTHER LIMIT INSOLATION. THEREFORE, TEMPERATURES FROM DODGE CITY EASTWARD WILL STAY AT OR BELOW FREEZING. SOME COLD AIR EROSION IS EXPECTED IN FAR WESTERN KANSAS WHERE TEMPERATURES COULD REACH INTO THE UPPER 30S AND 40S. THE OFFICIAL FORECAST WILL BE A FEW DEGREES COLDER THAN THE NAM. FOR SOME REASON THE RAP ERODES THE COLD AIR WITH HIGHS IN THE MID 40S EVEN AS FAR EAST AS DODGE CITY. BY TONIGHT, THE LOW LEVEL WINDS ARE EXPECTED TO VEER TO THE SOUTHWEST AS THE AFOREMENTIONED PACIFIC COLD FRONT APPROACHES. THUS THE LOW CLOUDS WILL RAPIDLY CLEAR OUT. TEMPERATURES WILL INITIALLY FALL INTO THE 20S OVERNIGHT BUT THEN HOLD STEADY OR EVEN RISE AFTER 3 AM AS VERTICAL MIXING INCREASES BEHIND THE PACIFIC COLD FRONT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 330 AM CST THU JAN 24 2013 FRIDAY WILL START WITH THE UPPER LEVEL FLOW OVER KANSAS IN A SLIGHT DOWNSLOPE PATTERN WITH NORTHWEST FLOW ALOFT. SKIES SHOULD START OUT FRIDAY MORNING SUNNY, WITH LIGHT NORTH TO NORTHWEST SURFACE WINDS. BY FRIDAY AFTERNOON, A FEW HIGH CIRRUS CLOUDS WILL STREAM IN WITH SKIES BECOMING MOSTLY SUNNY, AND WINDS SHIFTING TO THE SOUTH AT 10 MPH OR LESS. CLOUDS WILL CONTINUE TO INCREASE FRIDAY NIGHT. WINDS WILL REMAIN SOUTH AT AROUND 10 MPH, SO MINIMUM TEMPS WILL BE MILD IN THE MID 20S TO LOWER 30S. ON SATURDAY, AN UPPER LEVEL WAVE WILL BE APPROACHING FROM THE SOUTHWEST. PLENTY OF MOISTURE IS STILL SITTING OVER TEXAS AND WILL STILL BE THERE SATURDAY. THE DEEP, SOUTHWEST FLOW ALOFT WILL ADVECT SOME OF THAT MOISTURE NORTH INTO KANSAS. WHEN THAT UPPER WAVE APPROACHES LATE SATURDAY, THE MOISTURE WILL BE IN PLACE. THERE ARE SLIGHT CHANCES FOR RAIN IN OUR EAST VERY LATE ON SATURDAY, BUT PRECIPITATION CHANCES WILL INCREASE SATURDAY NIGHT AS THE UPPER LIFT MOVES IN. PRECIPITATION CHANCES WILL BE AS HIGH AS 50 PERCENT IN OUR EAST AND SOUTHEAST, BASICALLY EAST OF HIGHWAY 19. AS FOR PRECIPITATION, RAIN WILL DOMINATE, AND RAINFALL AMOUNTS WILL BE ON THE LIGHT SIDE. THE GFS MODEL HAS THE MOST PRECIP, WITH 0.25 IN OUR EAST, BUT THE GEM AND THE ECMWF MODELS BOTH PRODUCE LESS THAN A TENTH OF AN INCH OF RAINFALL SATURDAY AND SUNDAY MORNING. SUNDAY, PRECIP CHANCES WILL JUST BE ACROSS OUR EXTREME EASTERN TIER OF COUNTIES, FROM ELLIS SOUTH TO BARBER COUNTY. AFTER THIS WAVE PASSES SUNDAY, THE UPPER PATTERN WILL TURN TO THE SOUTHWEST, WITH A WARMING TREND. BY TUESDAY, MAX TEMPS SHOULD BE WELL INTO THE MID 50S NORTH OF I-70 TO THE MID 60S SOUTH ALONG THE OKLAHOMA BORDER. A LARGE, BROAD SCALE UPPER TROUGH WILL BE MOVING INTO THE PLAINS TUESDAY INTO WEDNESDAY, AND A LOW END SLIGHT CHANCE FOR RAIN WILL EXIST OVER OUR NORTHERN MOST COUNTIES OF ELLIS AND TREGO. I AM NOT TOO CONFIDENT IN THESE PRECIPITATION CHANCES TUESDAY AND WEDNESDAY, SO STAYED WITH LOW 15-16 PERCENT CHANCES ONLY, FOR NOW. FOR MOST OF THIS EXTENDED FORECAST, THE ECMWF MODEL WAS FAVORED. THE GFS SEEMS TOO WET AND SLOWER WITH THE UPPER PROGRESSION OF WAVES. THE GEM CANADIAN MODEL ON THE OTHER HAND IS FASTER AND LESS WET. THUS, THE ECMWF IS A GOOD COMPROMISE. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1139 AM CST THU JAN 24 2013 12Z BUFR SOUNDINGS SUGGESTING MVFR STATUS DECK WILL LINGER ACROSS ALL THE TAF SITES THROUGH AT LEAST THE LATE AFTERNOON. HRRR WAS A LITTLE MORE PESSIMISTIC KEEPING THE STATUS IN AT GCK UNTIL AROUND 00Z. AT THIS TIME GIVEN THE LATEST SATELLITE LOOP WHICH SUGGESTED SOME MID-HIGH LEVEL MOISTURE WAS ALREADY BEGINNING TO SPREAD INTO WESTERN KANSAS LATE THIS MORNING HAVE DECIDED TO FOLLOW THE SLOWER EROSION OF THE MVFR CIGS. AS A RESULT EXPECT CIGS TO REMAIN AS IS UNTIL 00Z FRIDAY AT GCK, 03Z AT DDC AND HYS. EASTERLY SURFACE WINDS AT 10KTS OR LESS WILL GRADUALLY SHIFT TO THE SOUTH/SOUTHWEST BY LATE DAY. && .PRELIMINARY POINT TEMPS/POPS... DDC 32 25 52 27 / 0 0 0 0 GCK 36 25 52 28 / 0 0 0 0 EHA 46 27 53 32 / 0 0 0 0 LBL 38 26 53 29 / 0 0 0 0 HYS 31 22 50 26 / 0 0 0 0 P28 31 27 53 26 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BURGERT SHORT TERM...FINCH LONG TERM...BURKE AVIATION...BURGERT
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
340 PM CST THU JAN 24 2013 .SHORT TERM... ISSUED AT 334 PM CST THU JAN 24 2013 (TONIGHT) THE MAIN ISSUE FOR TONIGHT IS WHETHER OR NOT WE WILL SEE SOME LIGHT WINTRY PRECIPITATION. THE OVERALL SYNOPTIC SCENARION APPEARS UNCHANGED. AN EXPANSIVE COLD HIGH PRESSURE SYSTEM CURRENTLY CENTERED THRU THE WRN GREAT LAKES WILL RETREAT EASTWARD THRU THE OH VALLEY AND INTO THE EASTERN U.S. BY DAYBREAK FRIDAY. IN THE PROCESS...LOW LEVEL FLOW WILL VEER TO MORE SELY TONIGHT AND A BROAD LOW LEVEL WAA REGIME WILL DEVELOP. CONCURRENTLY A VERY WEAK IMPULSE WILL TRACK THRU THE MID MS VALLEY WITHIN THE NW FLOW ALOFT. BOTH OF THESE FEATURES WILL PRODUCE SOME WEAK ASCENT WITH THE LOW LEVEL WAA MORE FOCUSED ACROSS SRN MO AND SRN IL WHILE THE MAIN ASCENT WITH THE UPPER DISTURBANCE WILL BE FOCUSED NORTH OF THE CWA. MOISTURE IS ALSO AN INSUE WITH HIGH LEVEL MOISTURE WITHIN THE NW FLOW ALOFT STREAMING ACROSS THE AREA WHILE THE SWLY LLJ TRANSPORTS MODEST LOW LEVEL MOISTURE FROM THE SRN PLAINS AND LOWER MS VALLEY. THE RESULTANT MOISTURE STRATIFICATION IS HIGH AND LOW WITH MOST OF THE LIFT INDICATED TO BE INBETWEEN THE TWO MOISTURE SOURCES WHERE THE AIR MASS IS DRY. NORMALLY THIS MIGHT SUGGEST DRIZZLY PCPN BUT THE LOW LEVELS WONT BE THAT DRAMATICALLY MOIST - I.E. IFR AND LOWER CIGS. THIS IS IN PART DUE TO THE DRY BOUNDARY LAYER CURRENTLY OVER THE AREA. THE GFS SEEMS TO RECOGNIZE THIS AS DOES THE HRRR AND RUC...WHICH HAVE NO QPF OR A COUPLE OF SPITS. ALTERNATIVELY THE NAM AND LOCAL WRF SUGGEST VERY LIGHT QPF OVER THE ENTIRE CWA...HOWEVER THEY ARE ALREADY IN ERROR AS THERE SHOULD BE PCPN ACROSS OK AND AR. ADDING TO THE QUANDRY IS THE THERMAL PROFILES WHICH SUGGEST SLEET OR FREEZING RAIN ACROSS SE MO AND MAINLY SNOW OR SLEET CENTERED ALONG I-70 AND SNOW FURTHER NORTH. THE BOTTOM LINE IS THAT I THINK DRIZZLE IS LESS LIKELY AND ANY PCPN THAT OCCURS WILL BE EITHER BE VERY LIGHT OR SHOWERY IN NATURE...WITH THE GREATEST PROBABILITY ACROSS SE MO AFTER 06Z. WHATEVER DOES FALL AND ACCUMULATE WILL BE VERY LIGHT. GIVEN THE UNCERTAINTIES I HAVE KEPT WITH THE CHANCE POPS FROM THE PREVIOUS FORECAST AND DONT HAVE ANY HEADLINES. THAT SAID...SOME ZL-- OR ZR-- COULD PRODUCE A VERY LIGHT GLAZE ON ANY UNTREATED SURFACES. I WILL ISSUE AN SPS TO HIGHLIGHT THIS POTENTIAL. GLASS && .LONG TERM... ISSUED AT 334 PM CST THU JAN 24 2013 (FRIDAY - SUNDAY) LIGHT PRECIPITATION SHOULD BE ON THE WAY OUT EARLY TOMORROW MORNING AS BY 1200 UTC NAM 290-305K ISENTROPIC SURFACES DEPICT SUBSIDENCE WEST OF THE MISSISSIPPI RIVER WHICH SPREADS EAST WITH TIME. LEFT SCHC POPS FOR THE EASTERN THIRD OF THE CWA WHERE WEAK MOIST/WARM ADVECTION CONTINUES UNTIL ROUGHLY 1500 UTC. SKIES SHOULD QUICKLY CLEAR OUT TOMORROW WITH SUBSIDENCE IN THE WAKE OF SHORTWAVE TROUGH PASSING THROUGH THE GREAT LAKES REGION. AT THE SFC...A WEAK COLD FRONT/WIND SHIFT WILL COME THROUGH ATTENDANT TO A SFC CYCLONE ASSOCIATED WITH THE NORTHERN STREAM CLIPPER. WITH CLEARING SKIES AND A WESTERLY COMPONENT TO THE WIND...WENT ABOVE WARMEST GUIDANCE YIELDING HIGHS FROM UPPER 30S IN THE NORTH TO NEAR 50 OVER PORTIONS OF SOUTHEAST MISSOURI. ANOTHER SHOT OF COLD CANADIAN AIR IS IN STORE FOR FRIDAY NIGHT AND SATURDAY WITH A 1030+ HPA SFC HIGH SLIDING SE INTO THE MID-MISSOURI RIVER VALLEY BY 0600 UTC SATURDAY. EXPECT LOWS IN THE TEENS AND TWENTIES WITH CLEAR SKIES AND LOW DEWPOINTS. WINDS SHOULD STAY UP JUST ENOUGH MOST LIKELY TO PREVENT DECOUPLING AND TEMPERATURES BOTTOMING OUT SEVERAL DEGREES COOLER. FOR HIGHS ON SATURDAY...COOLEST READINGS WILL BE IN THE M/U 20S OVER WEST-CENTRAL ILLINOIS AND MID 30S OVER CENTRAL MISSOURI. THESE READINGS ARE CLOSER TO COOLER MET GUIDANCE GIVEN WEAK CAA AND INCREASING CIRRUS THROUGHOUT THE DAY. CLOUDS SHOULD CONTINUE TO BE ON THE INCREASE AND GRADUALLY LOWER THROUGHT SATURDAY NIGHT AS A SHORTWAVE TROUGH EJECTS OUT OF THE DESERT SOUTHWEST. THE COMBINATION OF STRONG MOIST/WARM ADVECTION AROUND THE WESTERN PERIPHERY OF A LOW-LEVEL ANTICYCLONE OVER THE GULF COAST AND DCPVA AHEAD OF THE TROUGH AXIS SHOULD PROVIDE PLENTY OF SUPPORT FOR GOING POPS. WITH COLD AIR STILL IN PLACE BEHIND DEPARTING CANADIAN AIRMASS AND COLD GROUND TEMPERATURES FROM PREVIOUS SPELLS OF ARCTIC AIR...POTENTIAL FOR ACCUMULATING FREEZING RAIN APPEARS LIKELY FOR PORTIONS OF THE AREA. CURRENT EXPECTATION IS FOR FREEZING RAIN TO BEGIN LATE SATURDAY NIGHT OVER CENTRAL MISSOURI AND SPREADING E/NE WITH TIME. ONSET OF PRECIPITATION WILL LIKELY BE A COMBINATION OF SLEET/SNOW DUE TO VERY DRY AMS VELOW 700 HPA LEADING TO STRONG EVAPORATIONAL COOLING/WETBULBING. HOWEVER...WAA WILL WIN OUT FAIRLY QUICKLY (WITHIN AN HOUR OR TWO) AND CHANGE PTYPE OVER TO FREEZING RAIN AND EVENTUALLY RAIN AS SFC TEMPS WARM ABOVE FREEZING. EXCEPTION WOULD BE OVER NORTHERN SECTIONS OF THE AREA INCLUDING QUINCY WHERE SLEET/SNOW MIX MAY CONTINUE FOR A FEW HOURS BEFORE CHANGING OVER TO FREEZING RAIN. IN THIS AREA...HAVE HALF AN INCH OF SNOW OR LESS TO ACCOUNT FOR THIS SCENARIO. GENERALLY...EXPECTING A 6-HR PERIOD OR SO OF FROZEN PRECIPITATION WITH FREEZING RAIN BEING THE PRIMARY PTYPE BEFORE THE CHANGEOVER TO PLAIN OLD RAIN FOR MOST LOCATIONS. AMOUNTS OF FREEZING RAIN IN THE CURRENT FORECAST ARE ON THE ORDER OF A TENTH OF AN INCH OR LESS...BUT CERTAINLY ENOUGH TO CREATE TRAVEL PROBLEMS FOR THOSE VENTURING OUT SUNDAY MORNING. TEMPERATURES BEHIND THE WARM FRONT WILL CONTINUE TO RISE THROUGH THE OVERNIGHT HOURS SO WENT WITH A NON-DIURNAL TEMPERATURE TREND FOR SUNDAY NIGHT. (MONDAY - THURSDAY) VERY WARM AIR IS IN STORE FOR MONDAY-TUESDAY WITH HIGHS IN THE 50S AND 60S EACH DAY. MAIN CONCERN WITH REACHING THESE TEMPERATURES IS OBVIOUSLY CLOUDS/PRECIP CHANCES. MODELS CONTINUE TO PRINT OUT LIGHT QPF EACH DAY... BUT FORCING SEEMS INOCUOUS AND BELIEVE MODELS ARE DOING THIS DUE TO THE VERY STRONG AND ANOMALOUS LOW-LEVEL MOISTURE RETURN. WARMEST DAY SHOULD BE TUESDAY AHEAD OF FRONT AS NWP GUIDANCE HAS 850-HPA TEMPS AOA +8C. DEEP MIXING FOR THE TIME OF YEAR TO NEAR 850 HPA AND COMPRESSIONAL WARMING AHEAD OF FRONT ALL SUGGEST HIGHS NEAR RECORD OR RECORD-BREAKING. THEREFORE... HAVE OPTED TO INCLUDE RECORD HIGHS AND RECORD HIGH MINIMUMS FOR MONDAY AND TUESDAY IN THE CLIMO SECTION BELOW. HIGH TEMPERATURES...ESPECIALLY FOR TUESDAY...WOULD LIKELY BE SEVERAL DEGREES TOO COOL IF THERE ARE BREAKS IN THE CLOUDS. FOR EARLY WEEK...WENT AT LEAST A FEW DEGREES ABOVE CR INITIALIZATION DUE TO REASONING MENTIONED ABOVE. COLD FRONT SHOULD MOVE THROUGH ON THE DAY TUESDAY WITH SHOWERS AND THUNDERSTORMS STILL A GOOD BET ALONG AND AHEAD OF THE BOUNDARY. ALSO POTENTIAL FOR SEVERE WEATHER GIVEN STRONG DYNAMICS PROGGED AND INSTABILITY PARAMETERS. SFC DEWPOINTS MAY EVEN APPROACH 60 DEGREES...WHICH FOR THIS TIME OF YEAR IS CERTAINLY A RED FLAG FOR POTENTIAL STRONG TO SEVERE STORMS. HOWEVER...THERE IS STILL QUITE A BIT OF UNCERTAINTY IN REGARDS TO EXACT TRACK OF SFC LOW AND AMOUNT OF INSTABILITY AHEAD OF BOUNDARY. NEW ECMWF WHICH CUTS OFF SHORTWAVE TROUGH OFF THE COAST OF CALIFORNIA WITH A NORTHERN STREAM SHORTWAVE TRAVERSING THE NORTHERN PLAINS IS AN OUTLIER AND WAS DISCOUNTED FOR NOW. THIS SCENARIO WOULD HAVE A WEAKER FROPA EARLIER ON TUESDAY WITH LESS DYNAMICS FOR SEVERE WEATHER. BEHIND THE COLD FRONT...WEDNESDAY AND THURSDAY LOOK MUCH COOLER...I.E.... TOWARD SEASONAL NORMS WITH HIGHS IN THE 30S AND 40S. THIS TIME PERIOD ALSO WILL LIKELY BE DRY...THOUGH SOME MODELS HAVE HINTED AT THE POSSIBILITY OF SOME ENERGY LAGGING BEHIND IN THE FOUR-CORNERS REGION WHICH COULD YIELD POTENTIALLY WINTRY WEATHER SOMETIME LATER NEXT WEEK. GOSSELIN && .AVIATION... ISSUED AT 1127 AM CST THU JAN 24 2013 A SURFACE HIGH CURRENTLY CENTERED IN THE UPPER MS VALLEY WILL MOVE EAST THROUGH THE OH VALLEY OVER THE NEXT 24 HOURS RESULTING IN WINDS VEERING FROM EASTERLY THIS AFTERNOON TO SOUTHEASTERLY TONIGHT. THROUGH MUCH OF THE EVENING...VFR CONDITIONS ARE EXPECTED TO PREVAIL. MEANWHILE A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE LOWER MS VALLEY TONIGHT ALLOWING WARM AND MOIST AIR WILL RIDE UP AND OVER THE COLD AIR AT THE SURFACE....BRINGING THE POTENTIAL OF A LIGHT WINTRY MIX ACROSS EASTERN MISSOURI AND ILLINOIS LATE TONIGHT AND CIGS LOWERING TO MVFR. THERE STILL REMAINS MUCH UNCERTAINTY ON THE LIKELYHOOD OF ANY PRECIPITATION BUT IF IT OCCURS...AMOUNTS SHOULD BE QUITE LIGHT. I HAVE KEPT THE PROB30 GROUPS FROM 09-12Z TO ACCOUNT FOR THE PROBABILITY OF PRECIPITATION. CIGS SHOULD IMPROVE FROM WEST TO EAST ON FRIDAY MORNING INTO THE EARLY AFTERNOON AS A NEW COLD FRONT BRINGS A WESTERLY WIND SHIFT. SPECIFICS FOR KSTL... VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE EVENING AS WINDS GRADUALLY VEER FROM EASTERLY THIS AFTERNOON TO SOUTHEAST THIS EVENING. A STORM SYSTEM TO THE SOUTH COULD PRODUCE A LIGHT WINTRY MIX BETWEEN 09-12Z WITH CIGS LOWERING TO MVFR. THERE STILL REMAINS MUCH UNCERTAINTY ON THE LIKELYHOOD OF ANY PRECIPITATION BUT IF IT OCCURS...AMOUNTS SHOULD BE QUITE LIGHT AND THE MOST LIKELY PTYPES ARE SLEET AND FREEZING DRIZZLE. CIGS SHOULD LIFT BY EARLY AFTERNOON AS A NEW COLD FRONT BRINGS A WESTERLY WIND SHIFT. GLASS && .CLIMATE... ISSUED AT 334 PM CST THU JAN 24 2013 RECORD OR NEAR RECORD-BREAKING TEMPERATURES ARE EXPECTED ON MONDAY AND TUESDAY. BELOW IS A TABLE OF RECORD HIGHS AND RECORD HIGH MINIMUMS FOR ARE THREE OFFICIAL CLIMATE STATIONS: ST. LOUIS (STL)...COLUMBIA (COU)...AND QUINCY (UIN): ST. LOUIS HIGH HIGH MINIMUM 1/2876 (1970)53 (1914) 1/2973 (2008)44 (1947) COLUMBIA HIGH HIGH MINIMUM 1/28 67 (2002) 53 (1914) 1/29 64 (2008) 44 (1938) QUINCY HIGH HIGH MINIMUM 1/28 63 (1914) 46 (1914) 1/29 63 (1914) 38 (1989) && .PRELIMINARY POINT TEMPS/POPS... ST LOUIS 23 45 22 31 / 40 20 5 0 QUINCY 19 37 14 26 / 50 10 5 0 COLUMBIA 23 46 20 36 / 20 10 5 0 JEFFERSON CITY 25 47 19 37 / 20 10 5 0 SALEM 23 42 22 30 / 50 20 5 0 FARMINGTON 25 48 22 34 / 50 20 5 0 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
254 PM CST THU JAN 24 2013 .SHORT TERM...TONIGHT THROUGH FRIDAY AFTERNOON...PLENTY OF CLOUD COVER ACROSS THE REGION THIS AFTERNOON AS A WARM FRONT ACROSS WESTERN NEBRASKA IS SLOWLY PROGRESSING EASTWARD. THIS THICK CLOUD COVER HAS LIMITED SOLAR HEATING TODAY...AND WITH A COLD AIRMASS IN PLACE...HAVE STRUGGLED TO CLIMB OUT OF THE TEENS SO FAR IN SPOTS...WHILE IN WESTERN NEBRASKA BEHIND THE WARM FRONT... TEMPERATURES MANAGED TO CLIMB INTO THE LOWER 60S. AS THIS WARM FRONT CROSS THE LOCAL AREA DURING THE EVENING HOURS...EXPECT LOW TEMPERATURES TO BE REALIZED JUST AHEAD OF THE BOUNDARY PASSAGE...WITH STEADY OR SLOWLY RISING TEMPERATURES POSSIBLE OVERNIGHT. WITH HRRR AND NAM IN FAIR AGREEMENT...TAKING THIS FRONT ACROSS KGRI AROUND 3Z...WENT AHEAD AND ADJUSTED HOURLY TEMPERATURE GRIDS TO REFLECT LOW TEMPERATURES AT MOST AREAS BETWEEN 00Z AND 04Z THIS EVENING. OTHER THAN THE WARMER AIRMASS AND SWITCH TO MORE SOUTHWESTERLY WINDS WITH THE PASSAGE OF THIS FRONT...NO OTHER IMPACTS ARE EXPECTED. FOR FRIDAY...EXPECT THE WARMER AIRMASS IN PLACE ACROSS THE LOCAL AREA COMBINED WITH LIGHT WEST NORTHWESTERLY DOWNSLOPE FLOW...TO HELP AFTERNOON TEMPERATURES SOAR PAST SEASONAL NORMALS...WITH MID TO UPPER 40S FORECAST FOR MOST LOCATIONS. A PASSING SHORTWAVE OVER THE TOP OF THE RIDGE IS EXPECTED TO REMAIN WELL TO THE NORTH OF THE LOCAL AREA...WITH THE ASSOCIATED SURFACE COLD FRONT NOT EXPECTED TO REACH THE LOCAL AREA. THEREFORE...WITH THINNING CLOUD COVER BEHIND THE WARM FRONT AND LIGHT NORTHWESTERLY SURFACE WINDS...A MOSTLY SUNNY AND PLEASANT END TO THE WEEK IS EXPECTED ACROSS THE REGION. .LONG TERM...FRIDAY NIGHT THROUGH THURSDAY. MAIN FORECAST CONCERNS WILL BE CHANCE FOR PRECIPITATION SATURDAY NIGHT INTO SUNDAY AND AGAIN MONDAY NIGHT INTO TUESDAY AND TEMPERATURES THROUGH THE PERIOD. A BROAD UPPER LEVEL RIDGE WILL DRIFT THROUGH THE AREA FRIDAY NIGHT AND SATURDAY. TEMPERATURES FRIDAY NIGHT WILL STILL DROP INTO THE TEENS AND LOWER 20S. DURING THE DAY WINDS WILL TURN TO THE SOUTH AND WITH WARM ADVECTION THE TEMPERATURES SHOULD RISE INTO THE 40S TO LOWER 50S. BY SATURDAY NIGHT THERE IS AN UPPER LEVEL WAVE THAT MOVES INTO THE AREA. THE SOUTH WINDS DURING THE DAY ON SATURDAY WILL BRING MOIST AIR INTO THE AREA. BY SATURDAY NIGHT THERE ARE SOME DIFFERENCES IN THE LOCATION OF THE PRECIPITATION DURING THE NIGHT. THE GFS BRINGS MORE PRECIPITATION INTO THE AREA WHERE THE ECMWF AND THE NAM KEEP THE PRECIPITATION FURTHER TO THE SOUTH. HAVE LOWERED THE CHANCES FOR PRECIPITATION FOR THE NORTH AND WEST A BIT. THE QUESTION BECOMES WHAT TYPE OF PRECIPITATION TO EXPECT. MOST OF THE NIGHT THERE WILL BE RAIN AS THE TEMPERATURES WILL BE WARM ENOUGH FOR PRECIPITATION TO REMAIN LIQUID. THE PROBLEM BECOMES TOWARD MORNING AS PRECIPITATION SPREADS FURTHER TO THE NORTH. THERE COULD BE A BRIEF PERIOD OF SOME FREEZING RAIN FURTHER NORTH. BY SUNDAY MORNING THE TEMPERATURES SHOULD WARM UP AND PRECIPITATION SHOULD TURN TO RAIN ACROSS THE AREA. BY LATER IN THE DAY ON SUNDAY THE RAIN SHOULD START TO MOVE OUT OF THE AREA. SUNDAY NIGHT AND MONDAY THERE WILL BE A DEVELOPING WAVE IN THE WESTERN CONUS AND SOUTHWEST FLOW ACROSS THE AREA. THERE WILL BE WARM ADVECTION AND MILD TEMPERATURES. BY MONDAY NIGHT THE UPPER LEVEL WAVE STARTS TO AFFECT THE FORECAST AREA. MODELS HAVE SOME DIFFERENCES IN THE PROGRESSION OF THE WAVE ACROSS THE AREA. THE GFS IS FASTER WITH A MORE OPEN WAVE WHILE THE ECMWF IS SLOWER WITH A CLOSED LOW. HAVE KEPT THE PRECIPITATION IN ACROSS THE AREA FOR MONDAY NIGHT INTO TUESDAY WHICH IS CLOSER TO THE GFS. THERE IS COLDER AIR MOVING INTO THE AREA BEHIND A COLD FRONT THAT MOVES THROUGH MONDAY NIGHT. EXPECT RAIN OR SNOW MONDAY NIGHT WITH THE COLDER AIR MOVING INTO THE AREA. THEN ON TUESDAY THERE WILL BE SNOW FURTHER WEST OR NORTHWEST WHERE THE COLDER AIR IS...RAIN IN THE SOUTHEAST AND A MIX OF RAIN OR SNOW POSSIBLE IN BETWEEN. COLD AIR CONTINUES ACROSS THE AREA ON WEDNESDAY BUT THERE IS A LITTLE WARM ADVECTION AND TEMPERATURES WARM A LITTLE FOR THURSDAY. && .PREV DISCUSSION... /ISSUED 1134 AM CST THU JAN 24 2013/ AVIATION...PREVAILING VFR CONDITIONS ARE EXPECTED AT KGRI FOR AT LEAST THE NEXT 24 HOURS. PLENTY OF HIGH CLOUD COVER IS EXPECTED ACROSS THE TERMINAL THROUGH THE PERIOD...WITH A BRIEF PERIOD OF MVFR CIGS THIS AFTERNOON...WITH THE PRIMARY FOCUS BEING ON WIND DIRECTION AND SPEED. EXPECT THE AREA OF SURFACE HIGH PRESSURE ACROSS MINNESOTA THIS MORNING TO SLIP SOUTH THROUGH THE AFTERNOON HORUS...AS A WARM FRONT APPROACHES FROM THE WEST. THIS SHOULD ACT TO TIGHTEN THE LOCAL PRESSURE GRADIENT...WITH WINDS INCREASING AND SHIFTING FROM THE SOUTHEAST TO SOUTHWEST BY AFTERNOON. AFTER THE PASSAGE OF THIS WARM FRONT...EXPECT WINDS TO SHIFT AND BECOME NORTHWESTERLY DURING THE OVERNIGHT HOURS...WITH 30 TO 35KTS OF LLWS POSSIBLE AROUND THE PASSAGE OF THIS BOUNDARY. KEPT MENTION OF LLWS OUT OF TAF FOR TIME BEING...BUT MAY NEED TO CONSIDER FOR 00Z TAF. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1202 PM CST THU JAN 24 2013 .AVIATION... MAIN AVIATION FORECAST CONCERN CENTERS ON THE TIMING AND SOUTHWARD EXTENT OF COLD FRONT CURRENTLY LOCATED OVER EXTREME SRN OK/WRN N TX. THIS BOUNDARY HAS SHOWN LITTLE SWD MOTION IN THE PAST 4 HOURS. HOWEVER...BASED ON VERY MODEST SHORT-TERM PRESSURE RISES OVER W OK...BELIEVE IT WILL HAVE ENOUGH MOMENTUM TO REACH THE METROPLEX TAF SITES DURING THE 02-03Z TIMEFRAME. THIS WILL RESULT IN A SHIFT TO LIGHT NORTHERLY WINDS IN THIS AREA. EXTENSIVE POST- FRONTAL STRATUS OVER OK WILL REMAIN N OF THE METROPLEX UNTIL 08Z OR LATER...AT WHICH TIME MVFR CEILINGS WILL LIKELY MOVE INTO THE AREA AND PERSIST THRU AT LEAST MID MORNING FRIDAY. IN THE WACO AREA...EXPECT VFR CONDITIONS UNTIL 09Z...AT WHICH TIME STRATUS/AREAS OF FOG WILL LIKELY DEVELOP AS IN PREVIOUS MORNINGS. COLD FRONT WILL BE MUCH DELAYED IN REACHING KACT...BUT DO EXPECT ARRIVAL...AND ASSOCIATED NORTHERLY WIND SHIFT BY AROUND FRI/15Z. 66 && .UPDATE... THE DENSE FOG ADVISORY WAS ALLOWED TO EXPIRE AT 10 AM. PATCHY FOG PERSISTS IN A FEW OF THE EASTERN AND NORTHERN AREAS...BUT VISIBILITIES WILL CONTINUE TO IMPROVE LATE THIS MORNING. THE COLD FRONT WAS LOCATED VERY CLOSE TO THE RED RIVER ON THE 16Z ANALYSIS AND HAS SHOWN A VERY SLOW SOUTHWARD PROGRESSION. THE FRONT IS EXPECTED TO CONTINUE A SLOW SOUTHWARD PUSH AS PER OUR CURRENT FORECAST. THE TIGHT TEMPERATURE GRADIENT NEAR THE FRONT WILL PLAY HAVOC WITH THE TEMPERATURE FORECAST TODAY AND TONIGHT. EXPECT TEMPERATURES TO REMAIN OR FALL INTO THE UPPER 50S NORTH OF THE FRONT...WITH TEMPERATURES SOARING WELL INTO THE 70S IN MOST AREAS SOUTH OF THE FRONT. MORNING SOUNDING HERE IN FORT WORTH SUGGESTS THAT TEMPERATURES WILL LIKELY RISE SLIGHTLY ABOVE THE PREVIOUS FORECAST HIGH TEMPERATURES IN AREAS SOUTH OF THE SLOWLY ADVANCING COLD FRONT. WE EXPECT AREAS THAT WILL RECEIVE NEARLY FULL SUN THIS AFTERNOON WILL APPROACH 80F AS WINDS TEND TO VEER TO SOUTHWEST OR WEST AHEAD OF THE FRONT. THE RECORD HIGH AT DFW TODAY IS 82...AND THE RECORD HIGH AT WACO IS 83. THE CURRENT FORECASTS FOR THIS AFTERNOON AT DFW /79F/ AND AT WACO /80F/ WILL FALL A FEW DEGREES SHORT OF THE RECORD HIGHS. IN THE EASTERN ZONES...GENERALLY EAST OF A LINE FROM MCKINNEY TO HEARNE...THE LOW CLOUDS WILL HOLD HIGH TEMPERATURES DOWN INTO THE UPPER 60S AND LOWER 70S. AND TEMPERATURES IN THE COUNTIES ALONG THE RED RIVER WILL BE DEPENDENT ON THE EXACT POSITION OF THE FRONT AS DISCUSSED ABOVE. NO CHANGES TO LATER PERIODS OF FORECAST AT THIS TIME. 09/GP && .PREV DISCUSSION... /ISSUED 339 AM CST THU JAN 24 2013/ UPPER LEVEL RIDGE IS NOW CENTERED SOUTHWEST OF THE AREA WITH HIGH CLOUDS STREAMING OVER THE TOP OF THE RIDGE AND INTO THE STATE. AT THE SURFACE...SOME STRATUS CLOUDS ARE NOW DEVELOPING ACROSS SOUTHEAST TEXAS...BUT ARE MOVING TO THE EAST AND NORTHEAST. SOME LOW CLOUDS WILL OCCUR OVER THE SOUTHEASTERN COUNTIES THIS MORNING...BUT SHOULD DISSIPATE BEFORE MIDDAY. IN ADDITION...THERE IS SOME SCATTERED PATCHY OF FOG ASSOCIATED WITH THE LOW CLOUDS IN SOUTHEAST TEXAS. AT THIS TIME DO NOT HAVE FOG MENTIONED IN THE GRIDS AS CURRENT THINKING IS THAT MOST OF THE FOG WILL STAY JUST OUTSIDE OUR AREA...BUT WILL UPDATE IF THE FOG BECOMES MORE WIDESPREAD. WILL ALSO BE MONITORING FOR FOG DEVELOPMENT NEAR THE RED RIVER THIS MORNING AS A COLD FRONT APPROACHES AND THE WINDS BECOME LIGHT. THE COLD FRONT HAS NOW PUSHED INTO SOUTHERN OKLAHOMA WITH TEMPERATURES IN THE 30S AND 40S BEHIND THE FRONT. THIS FRONT WILL EDGE JUST SOUTH OF THE RED RIVER TODAY...RESULTING IN MUCH COOLER TEMPERATURES ACROSS OUR NORTHERN COUNTIES. HIGH TEMPERATURES THIS AFTERNOON WILL RANGE FROM THE UPPER 50S ALONG THE RED RIVER TO NEAR 80 DEGREES IN OUR SOUTHWESTERN COUNTIES. HIGH CLOUDS ACROSS THE REGION AND SOME LOWER LEVEL CLOUDS DEVELOPING BEHIND PARTS OF THE FRONT WILL KEEP TEMPERATURES ON THE COOLER SIDE OF GUIDANCE TODAY. YESTERDAY...IT APPEARED THAT THE FRONT WOULD STALL OR EVEN RETREAT A LITTLE NEAR THE RED RIVER TONIGHT. HOWEVER...HI-RES GUIDANCE INCLUDING THE RAP AND TEXAS TECH WRF ALL SUPPORT THE NAM WHICH BEGINS TO PUSH THE FRONT SOUTH TONIGHT. WITH THE COLD TEMPERATURES THAT ARE ALREADY OCCURRING BEHIND THE FRONT...THIS SOLUTION IS THE MOST PLAUSIBLE ONE AND WILL SHOW THE FRONT SLOWLY MOVING SOUTH AFTER SUNSET. THE FRONT WILL CONTINUE MOVING SOUTH ON FRIDAY...HAVING MADE ITS WAY ALMOST ENTIRELY THROUGH THE CWA BY MIDDAY. TEMPERATURES TONIGHT WILL AGAIN BE VARIABLE WITH OVERNIGHT LOWS BEHIND THE FRONT IN THE 30S AND LOWER 40S...BUT UP TO THE UPPER 50S AHEAD OF THE FRONT. THERE IS STILL A LOW CHANCE FOR DRIZZLE OR VERY LIGHT RAIN OVER THE FAR NORTHEASTERN COUNTIES TONIGHT. FRIDAY THROUGH SATURDAY WILL CONTINUE TO BE COOL BEHIND THE FRONT. WENT WITH THE COOLER GUIDANCE ON SATURDAY ANTICIPATING MOSTLY CLOUDY SKIES AND POSSIBLY SOME ADDITIONAL LIGHT RAIN. THIS CHANCE FOR LIGHT RAIN WILL BE ASSOCIATED WITH A WEAK SHORTWAVE LIFTING NORTHEAST ACROSS THE SOUTHWEST CONUS AND INTO THE PLAINS. THE TRACK OF THIS SHORTWAVE IS SLIGHTLY FARTHER NORTH TONIGHT WITH THE BEST CHANCES FOR RAIN NORTH OF THE REGION. THEREFORE REDUCED POPS TO ONLY 20 PERCENT OF LIGHT RAIN...AND REMOVED THE POPS FROM SUNDAY AS THE SHORTWAVE WILL BE CROSSING OUT OF THE PLAINS BY THEN. AGAIN...ANY PRECIPITATION ON SATURDAY MAY LIKELY ONLY BE DRIZZLE INDUCED BY SOME ISENTROPIC LIFT OVER THE COOL SURFACE LAYER. AFTER SATURDAY...SOUTH TO SOUTHWEST FLOW IN THE LOW TO MID LEVELS OF THE ATMOSPHERE WILL RESULT IN ANOTHER WARM UP. WE WILL SEE TEMPERATURES BACK THE 70S BY MONDAY...WITH BREEZY WINDS AND MOSTLY CLOUDY SKIES. BOTH THE GFS AND ECMWF CONTINUE TO ADVERTISE A STRONGER UPPER LEVEL TROUGH MOVING THROUGH THE PLAINS AROUND THE MIDDLE OF NEXT WEEK...BUT THE LATEST ECMWF SOLUTION HAS CHANGED FROM THE PAST FEW RUNS WITH THE TROUGH NOW FARTHER NORTH AND MUCH BROADER. HOWEVER...IT STILL LOOKS LIKE NORTH AND CENTRAL TEXAS WILL HAVE A CHANCE FOR SHOWERS AND THUNDERSTORMS ON TUESDAY AS A DRYLINE AND COLD FRONT MOVE THROUGH THE REGION. SIDED WITH THE ECMWF IN THE EXTENDED BY CLEARING THE RAIN OUT WITH THE FRONT ON TUESDAY. THE REMAINDER OF THE FORECAST LOOKS DRY AS WE TRANSITION TO NORTHWEST AND/OR MORE ZONAL FLOW FOR A FEW DAYS. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 78 42 56 41 55 / 5 10 5 5 20 WACO, TX 80 53 62 44 62 / 10 10 10 10 20 PARIS, TX 59 39 53 35 53 / 10 20 10 5 20 DENTON, TX 72 40 53 38 53 / 5 10 5 5 20 MCKINNEY, TX 74 40 54 39 53 / 10 10 5 5 20 DALLAS, TX 78 43 57 42 55 / 5 10 5 5 20 TERRELL, TX 76 46 57 41 55 / 10 10 10 5 20 CORSICANA, TX 77 52 61 43 58 / 10 10 10 10 20 TEMPLE, TX 79 54 65 46 64 / 10 5 10 10 20 MINERAL WELLS, TX 74 39 56 39 54 / 5 5 0 5 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ /
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1054 AM CST THU JAN 24 2013 .UPDATE... THE DENSE FOG ADVISORY WAS ALLOWED TO EXPIRE AT 10 AM. PATCHY FOG PERSISTS IN A FEW OF THE EASTERN AND NORTHERN AREAS...BUT VISIBILITIES WILL CONTINUE TO IMPROVE LATE THIS MORNING. THE COLD FRONT WAS LOCATED VERY CLOSE TO THE RED RIVER ON THE 16Z ANALYSIS AND HAS SHOWN A VERY SLOW SOUTHWARD PROGRESSION. THE FRONT IS EXPECTED TO CONTINUE A SLOW SOUTHWARD PUSH AS PER OUR CURRENT FORECAST. THE TIGHT TEMPERATURE GRADIENT NEAR THE FRONT WILL PLAY HAVOC WITH THE TEMPERATURE FORECAST TODAY AND TONIGHT. EXPECT TEMPERATURES TO REMAIN OR FALL INTO THE UPPER 50S NORTH OF THE FRONT...WITH TEMPERATURES SOARING WELL INTO THE 70S IN MOST AREAS SOUTH OF THE FRONT. MORNING SOUNDING HERE IN FORT WORTH SUGGESTS THAT TEMPERATURES WILL LIKELY RISE SLIGHTLY ABOVE THE PREVIOUS FORECAST HIGH TEMPERATURES IN AREAS SOUTH OF THE SLOWLY ADVANCING COLD FRONT. WE EXPECT AREAS THAT WILL RECEIVE NEARLY FULL SUN THIS AFTERNOON WILL APPROACH 80F AS WINDS TEND TO VEER TO SOUTHWEST OR WEST AHEAD OF THE FRONT. THE RECORD HIGH AT DFW TODAY IS 82...AND THE RECORD HIGH AT WACO IS 83. THE CURRENT FORECASTS FOR THIS AFTERNOON AT DFW /79F/ AND AT WACO /80F/ WILL FALL A FEW DEGREES SHORT OF THE RECORD HIGHS. IN THE EASTERN ZONES...GENERALLY EAST OF A LINE FROM MCKINNEY TO HEARNE...THE LOW CLOUDS WILL HOLD HIGH TEMPERATURES DOWN INTO THE UPPER 60S AND LOWER 70S. AND TEMPERATURES IN THE COUNTIES ALONG THE RED RIVER WILL BE DEPENDENT ON THE EXACT POSITION OF THE FRONT AS DISCUSSED ABOVE. NO CHANGES TO LATER PERIODS OF FORECAST AT THIS TIME. 09/GP && .AVIATION... METROPLEX... WIDESPREAD FOG WITH VISIBILITIES OF LESS THAN 1 MILE SHOULD BE MAINLY NORTH AND EAST OF THE METROPLEX TAF SITES THIS MORNING. HAVE PLACED 6SM BR...BUT BE AWARE THAT SOME BRIEF GROUND FOG MAY QUICKLY DROP VISIBILITIES TO 1SM OR LESS BETWEEN 13-16Z. SOUTHERLY WINDS SHOULD INCREASE TO AROUND 10 KNOTS BY 16Z WHICH SHOULD DISPERSE ANY REMAINING FOG. A COLD FRONT THAT EXTENDS SOUTH OF A MCALESTER OKLAHOMA /KMLC/ TO WICHITA FALLS /KSPS/ TO PLAINVIEW /KPVW/ LINE AT 6 AM WILL MOVE INTO THE METROPLEX TAF SITES BETWEEN 01 AND 03Z. HAVE INDICATED 36007KT AT 03Z IN THE METROPLEX TAFS. AS MOISTURE IS LIFTED ABOVE THE FRONT...SOME MVFR STRATUS MAY DEVELOP BY 08Z. WACO...IFR CONDITIONS ARE EXPECTED IN THE WACO AREA THROUGH 16Z. AREAS OF FOG AND MAYBE LOW CLOUDS WILL AFFECT THE WACO AREA THIS MORNING. VISIBILITIES MAY BRIEFLY FALL TO 1/4 MILE OR LESS...BUT SHOULD MAINLY BE 1/2 MILE OR GREATER. VFR CONDITIONS SHOULD RETURN BETWEEN 16 AND 17Z. A COLD FRONT IS EXPECTED TO APPROACH WACO 09-10Z FRIDAY...SO HAVE PLACED A WIND SHIFT TO 32006KT AT 09Z. 58 && .PREV UPDATE... .UPDATE... DESPITE WINDS OF 5 TO 10 MPH...THE FOG HAS BECOME MORE WIDESPREAD THIS MORNING AND WILL UPDATE TO INCLUDE FOG THROUGH THE MID MORNING HOURS. AREAS ALONG THE RED RIVER ARE REPORTING DENSE FOG WHERE THE WINDS HAVE BECOME LIGHT. ELSEWHERE...DENSE FOG IS BEING REPORTED IN ISOLATED AREAS ACROSS THE EASTERN COUNTIES...EAST OF THE HWY 75/I-45 CORRIDORS. WILL ISSUE A DENSE FOG ADVISORY FOR THESE TWO AREAS. 82/JLD && .PREV DISCUSSION... /ISSUED 339 AM CST THU JAN 24 2013/ UPPER LEVEL RIDGE IS NOW CENTERED SOUTHWEST OF THE AREA WITH HIGH CLOUDS STREAMING OVER THE TOP OF THE RIDGE AND INTO THE STATE. AT THE SURFACE...SOME STRATUS CLOUDS ARE NOW DEVELOPING ACROSS SOUTHEAST TEXAS...BUT ARE MOVING TO THE EAST AND NORTHEAST. SOME LOW CLOUDS WILL OCCUR OVER THE SOUTHEASTERN COUNTIES THIS MORNING...BUT SHOULD DISSIPATE BEFORE MIDDAY. IN ADDITION...THERE IS SOME SCATTERED PATCHY OF FOG ASSOCIATED WITH THE LOW CLOUDS IN SOUTHEAST TEXAS. AT THIS TIME DO NOT HAVE FOG MENTIONED IN THE GRIDS AS CURRENT THINKING IS THAT MOST OF THE FOG WILL STAY JUST OUTSIDE OUR AREA...BUT WILL UPDATE IF THE FOG BECOMES MORE WIDESPREAD. WILL ALSO BE MONITORING FOR FOG DEVELOPMENT NEAR THE RED RIVER THIS MORNING AS A COLD FRONT APPROACHES AND THE WINDS BECOME LIGHT. THE COLD FRONT HAS NOW PUSHED INTO SOUTHERN OKLAHOMA WITH TEMPERATURES IN THE 30S AND 40S BEHIND THE FRONT. THIS FRONT WILL EDGE JUST SOUTH OF THE RED RIVER TODAY...RESULTING IN MUCH COOLER TEMPERATURES ACROSS OUR NORTHERN COUNTIES. HIGH TEMPERATURES THIS AFTERNOON WILL RANGE FROM THE UPPER 50S ALONG THE RED RIVER TO NEAR 80 DEGREES IN OUR SOUTHWESTERN COUNTIES. HIGH CLOUDS ACROSS THE REGION AND SOME LOWER LEVEL CLOUDS DEVELOPING BEHIND PARTS OF THE FRONT WILL KEEP TEMPERATURES ON THE COOLER SIDE OF GUIDANCE TODAY. YESTERDAY...IT APPEARED THAT THE FRONT WOULD STALL OR EVEN RETREAT A LITTLE NEAR THE RED RIVER TONIGHT. HOWEVER...HI-RES GUIDANCE INCLUDING THE RAP AND TEXAS TECH WRF ALL SUPPORT THE NAM WHICH BEGINS TO PUSH THE FRONT SOUTH TONIGHT. WITH THE COLD TEMPERATURES THAT ARE ALREADY OCCURRING BEHIND THE FRONT...THIS SOLUTION IS THE MOST PLAUSIBLE ONE AND WILL SHOW THE FRONT SLOWLY MOVING SOUTH AFTER SUNSET. THE FRONT WILL CONTINUE MOVING SOUTH ON FRIDAY...HAVING MADE ITS WAY ALMOST ENTIRELY THROUGH THE CWA BY MIDDAY. TEMPERATURES TONIGHT WILL AGAIN BE VARIABLE WITH OVERNIGHT LOWS BEHIND THE FRONT IN THE 30S AND LOWER 40S...BUT UP TO THE UPPER 50S AHEAD OF THE FRONT. THERE IS STILL A LOW CHANCE FOR DRIZZLE OR VERY LIGHT RAIN OVER THE FAR NORTHEASTERN COUNTIES TONIGHT. FRIDAY THROUGH SATURDAY WILL CONTINUE TO BE COOL BEHIND THE FRONT. WENT WITH THE COOLER GUIDANCE ON SATURDAY ANTICIPATING MOSTLY CLOUDY SKIES AND POSSIBLY SOME ADDITIONAL LIGHT RAIN. THIS CHANCE FOR LIGHT RAIN WILL BE ASSOCIATED WITH A WEAK SHORTWAVE LIFTING NORTHEAST ACROSS THE SOUTHWEST CONUS AND INTO THE PLAINS. THE TRACK OF THIS SHORTWAVE IS SLIGHTLY FARTHER NORTH TONIGHT WITH THE BEST CHANCES FOR RAIN NORTH OF THE REGION. THEREFORE REDUCED POPS TO ONLY 20 PERCENT OF LIGHT RAIN...AND REMOVED THE POPS FROM SUNDAY AS THE SHORTWAVE WILL BE CROSSING OUT OF THE PLAINS BY THEN. AGAIN...ANY PRECIPITATION ON SATURDAY MAY LIKELY ONLY BE DRIZZLE INDUCED BY SOME ISENTROPIC LIFT OVER THE COOL SURFACE LAYER. AFTER SATURDAY...SOUTH TO SOUTHWEST FLOW IN THE LOW TO MID LEVELS OF THE ATMOSPHERE WILL RESULT IN ANOTHER WARM UP. WE WILL SEE TEMPERATURES BACK THE 70S BY MONDAY...WITH BREEZY WINDS AND MOSTLY CLOUDY SKIES. BOTH THE GFS AND ECMWF CONTINUE TO ADVERTISE A STRONGER UPPER LEVEL TROUGH MOVING THROUGH THE PLAINS AROUND THE MIDDLE OF NEXT WEEK...BUT THE LATEST ECMWF SOLUTION HAS CHANGED FROM THE PAST FEW RUNS WITH THE TROUGH NOW FARTHER NORTH AND MUCH BROADER. HOWEVER...IT STILL LOOKS LIKE NORTH AND CENTRAL TEXAS WILL HAVE A CHANCE FOR SHOWERS AND THUNDERSTORMS ON TUESDAY AS A DRYLINE AND COLD FRONT MOVE THROUGH THE REGION. SIDED WITH THE ECMWF IN THE EXTENDED BY CLEARING THE RAIN OUT WITH THE FRONT ON TUESDAY. THE REMAINDER OF THE FORECAST LOOKS DRY AS WE TRANSITION TO NORTHWEST AND/OR MORE ZONAL FLOW FOR A FEW DAYS. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 79 42 56 41 55 / 5 10 5 5 20 WACO, TX 80 53 62 44 62 / 10 10 10 10 20 PARIS, TX 59 39 53 35 53 / 10 20 10 5 20 DENTON, TX 72 40 53 38 53 / 5 10 5 5 20 MCKINNEY, TX 74 40 54 39 53 / 10 10 5 5 20 DALLAS, TX 78 43 57 42 55 / 5 10 5 5 20 TERRELL, TX 76 46 57 41 55 / 10 10 10 5 20 CORSICANA, TX 77 52 61 43 58 / 10 10 10 10 20 TEMPLE, TX 79 54 65 46 64 / 10 5 10 10 20 MINERAL WELLS, TX 74 39 56 39 54 / 5 5 0 5 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
230 PM CST THU JAN 24 2013 .SHORT TERM...TONIGHT AND FRIDAY. LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH PRESSURE CENTERED ACROSS THE STATE EARLY THIS AFTERNOON. MID AND HIGH CLOUDS ARE ALREADY ON THE INCREASE...HOWEVER...AHEAD OF THE NEXT SHORTWAVE TROUGH MOVING ESE OVER SOUTHERN SASKATCHEWAN. RADARS ARE PUSHING AN AREA OF LIGHT TO MODERATE SNOW OVER FAR NORTHERN NORTH DAKOTA AND SOUTHERN MANITOBA AND IS STARTING TO ENTER NORTHERN MINNESOTA. AS THE SHORTWAVE TRACKS TOWARDS THE REGION TONIGHT AND OVER THE REGION ON FRIDAY...SNOWFALL AMOUNTS AND HEADLINES ARE THE MAIN FORECAST CONCERNS. TONIGHT...SHORTWAVE TROUGH OVER THE SOUTHERN CANADIAN PRAIRIE WILL DIVE SOUTHEAST TONIGHT ON ITS WAY TO THE ARROWHEAD OF MINNESOTA BY 12Z FRIDAY. AHEAD OF THE SHORTWAVE...FORCING IN THE FORM OF DPVA AND ISENTROPIC ASCENT ON THE 280-285K SURFACES WILL SPREAD SOUTHEAST WHICH WILL LEAD TO A WARM ADVECTION BAND ENTERING NW WISCONSIN BY 00-03Z AND NORTH-CENTRAL AND NORTHEAST WISCONSIN IN THE 03-06Z TIME PERIOD. PLENTY OF UNCERTAINTY WITH THE DETAILS...INCLUDING WHERE AND WHEN THE BAND ENTERS THE FORECAST AREA...AND ALSO SNOWFALL RATIOS. THE LATEST SHORTER RANGE GUIDANCE INDICATES THAT A WARM ADVECTION SNOW BAND WILL DIVE SE INTO RHI-GRB LINE BETWEEN 03-06Z BEFORE WIDESPREAD SNOW ENTERS THE AREA AFTER MIDNIGHT. FGEN AND INSTABILITY ALOFT ARE NOT PARTICULARLY IMPRESSIVE...BUT MICROPHYSICS ARE A DIFFERENT STORY. BUFKIT SOUNDINGS FOR THE BOTH THE NAM/GFS INDICATE AN ISOTHERMAL LAYER FROM THE SURFACE TO ABOUT 575MB...FIRMLY IN THE DENDRITIC GROWTH ZONE. ASCENT WONT OCCUPY THIS ENTIRE LAYER...BUT SHOULD COINCIDE FOR ABOUT 200MB FROM LATE THIS EVENING THROUGH EARLY FRIDAY MORNING. AS A RESULT...DESPITE MEDIOCRE FORCING AND INSTABILITY...SHOULDNT TAKE MUCH QPF IN ORDER TO GET A SUBSTANTIAL AMOUNT OF SNOW. ESTIMATING SNOWFALL RATIOS OF 20-30:1 WILL YIELD WIDESPREAD 2-4 INCH AMOUNTS BY MORNING FROM NORTH-CENTRAL WISCONSIN TO THE SOUTHERN FOX VALLEY. WILL ADD WAUPACA AND THE REST OF THE FOX VALLEY/LAKESHORE TO THE WINTER WEATHER ADVISORY SINCE THE SNOW WILL BE FLYING DURING THE MORNING RUSH HOURS WHERE 2-3 INCHES WILL PROBABLY ALREADY HAVE FALLEN. WILL ALSO BUMP UP THE START TIME OVER N-C WISCONSIN TO START IT AT 03Z. FRIDAY...THE SHORTWAVE WILL PASS ACROSS THE AREA DURING THE DAY...AND IT WILL PUSH A SURFACE LOW ACROSS NORTHERN WISCONSIN DURING THE AFTERNOON. FORCING WILL BE SHIFTING TO THE SOUTHEAST FRIDAY MORNING...WHICH MAY LEAD TO SOME DRY SLOTTING OVER CENTRAL AND EAST-CENTRAL WISCONSIN. BUT DEEPER COMMA HEAD MOISTURE DOES PASS OVER NORTH-CENTRAL AND NORTHEAST WISCONSIN DURING THE DAY...WHERE HIGHER ACCUMS SHOULD RESIDE. WILL STILL HAVE THE VERY GOOD SNOW RATIOS FOR MUCH OF THE DAY...AND CAN SEE ADDITIONAL 1-2 INCHES OVER NORTHEAST HALF OF THE FORECAST AREA...AND LESS THAN AN INCH OVER THE SOUTHWEST. WINDS MAY START TO GET GUSTY LATE IN THE AFTERNOON...WHICH MAY LEAD TO MINOR BLOWING AND DRIFTING SNOW. HIGHS IN THE MID TEENS TO MID 20S. .LONG TERM...FRIDAY NIGHT THROUGH THURSDAY. CLIPPER SYSTEM WILL CONTINUE TO MOVE AWAY FROM THE AREA FRIDAY NIGHT. COULD BE A BRIEF PERIOD OF GUSTY WINDS AND BLOWING AND DRIFTING OF THE SNOW AS SYSTEM MOVES AWAY AND COLDER AIR FILTERS INTO THE REGION. WILL MENTION IT IN THE HAZARDOUS WEATHER OUTLOOK... BUT WILL NOT HAVE IT IN THE GRIDS DUE TO THE BRIEF NATURE OF THE EVENT. OTHERWISE...LAKE EFFECT SNOW SHOWERS WILL CONTINUE THROUGH MOST OF THE NIGHT ACROSS THE FAR NORTH. HAVE INCREASED POPS INTO THE CATEGORICAL RANGE FOR VILAS COUNTY AND INCREASED POPS OVER THE REMAINDER OF THE NORTH AS WELL. DID ADD A CHANCE OF FLURRIES THROUGH MOST OF THE NIGHT ACROSS THE SOUTH UNTIL CLEARING ARRIVES. DID SLOW THE ARRIVAL OF THE CLEARING BY SEVERAL HOURS...MAINLY DUE TO COLD NORTHERLY FLOW OFF THE WARMER WATERS OF LAKE SUPERIOR. MODELS DO SHOW DRYING OF THE 850MB MOISTURE TOWARDS 12Z ACROSS CENTRAL WISCONSIN. ON SATURDAY...DID LEAVE A FEW LINGERING FLURRIES FOR A FEW HOURS SATURDAY MORNING ACROSS THE FAR NORTH/NORTHEAST. WITH SUCH A COLD AIR MASS IN PLACE...ANY CUMULUS CLOUD COULD PRODUCE A FEW FLURRIES BEFORE DISSIPATING. NEW QUESTIONS ARISE FOR THE SATURDAY NIGHT PERIOD. LATEST WRF/CANADIAN NOW PRODUCE A FEW INCHES OF LIGHT SNOW ACROSS CENTRAL AND NORTHERN WISCONSIN...WHILE THE GFS/ECMWF DO NOT SHOW THIS FEATURE. WILL HAVE A SLIGHT CHANCE OF LIGHT SNOW ACROSS THE NORTH FOR NOW. CONFIDENCE REMAINS LOW THROUGHOUT THE REST OF THE FORECAST PERIOD WITH HANDLING OF SYSTEM SUNDAY NIGHT AND SUNDAY NIGHT...AND AGAIN TUESDAY. LATEST CANADIAN/ECMWF MODELS HAVE SHIFTED SYSTEM SUNDAY/ SUNDAY NIGHT FURTHER SOUTH AND WOULD JUST CLIP OUR FAR SOUTH. SINCE MODELS HAVE BEEN JUMPING AROUND SIGNIFICANT ON LOCATION OF THIS SYSTEM... WILL CONTINUE WITH PERSISTENCE FOR NOW UNTIL THERE IS A CLEAR TREND. PRECIPITATION TYPE ISSUES STILL CONTINUE WITH THIS SYSTEM WILL PRECIPITATION COULD END UP AS LIGHT SNOW...FREEZING RAIN OR SLEET. THE SYSTEM FOR TUESDAY CONTINUE TO BE PROBLEMATIC AS THE ECMWF CONTINUES TO GO BACK AND FORTH WITH SURFACE LOW TRACKING WEST OF GREEN BAY. THE GFS CONTINUED THIS TREND ON THE MORNING RUN...BUT 12Z ECMWF HAS NO SUCH FEATURE ON THIS RUN. WILL CONTINUE WITH PERSISTENCE WITH THIS PERIOD AS WELL UNTIL MODELS CONVERGE ON A CLEAR SOLUTION. AT OR ABOVE NORMAL TEMPERATURES ARE EXPECTED MONDAY AND TUESDAY...THEN BELOW NORMAL TEMPERATURES ARE EXPECTED LATE NEXT WEEK AS ANOTHER SURGE OF ARCTIC AIR WILL SWEEP INTO THE NORTHERN UNITED STATES. && .AVIATION...ARCTIC HIGH PRESSURE OVERHEAD TODAY WILL LEAD TO GREAT FLYING CONDITIONS THIS AFTERNOON. CONDITIONS DETERIORATE THIS EVENING WHEN A BAND OF SNOW AHEAD OF A LOW PRESSURE SYSTEM DIVES SOUTHEAST INTO THE NORTHERN HALF OF THE STATE. AS THE CLOUD DECK LOWERS...OBSERVATIONS UPSTREAM SUGGEST IFR/LIFR VSBYS/CIGS ARE POSSIBLE AFTER MIDNIGHT INTO FRIDAY MORNING. SEVERAL INCHES OF FLUFFY SNOW IS LIKELY NORTH OF ROUTE 29. SNOW WILL BE GRADUALLY DIMINISHING FRIDAY AFTERNOON AND CONDITIONS WILL SLOWLY IMPROVE. MPC && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM CST FRIDAY FOR WIZ022-037>040-048>050-073-074. WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO NOON CST FRIDAY FOR WIZ005-010>013-018>021-030-031. && $$ MPC/ECKBERG