Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 11/30/13


AREA FORECAST DISCUSSION
NWS ALBANY NY
631 AM EST THU NOV 28 2013 .SYNOPSIS... LOW PRESSURE WILL CONTINUE TO DEEPEN AND INTENSIFY AS IT MOVES FURTHER NORTHEAST INTO THE CANADIAN MARITIMES...AS HIGH PRESSURE WILL ATTEMPT TO BUILD IN FROM THE SOUTHEAST. BLUSTERY AND COLD CONDITIONS ARE EXPECTED FOR THANKSGIVING TODAY WITH SOME LAKE EFFECT SNOW SHOWERS WEST OF THE GREATER CAPITAL REGION. A WEAK DISTURBANCE WILL BRING SOME LAKE EFFECT SNOW SHOWERS AND FLURRIES TONIGHT INTO EARLY FRIDAY MAINLY WEST OF THE HUDSON RIVER VALLEY...BEFORE HIGH PRESSURE BUILDS IN LATE FRIDAY INTO THE FIRST HALF OF THE WEEKEND WITH DRY WEATHER AND BELOW NORMAL TEMPERATURES TO CLOSE NOVEMBER. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM EST...HAPPY THANKSGIVING EVERYONE ! BLUSTERY AND COLD CONDITIONS GREET ERN NY AND WRN NEW ENGLAND THIS MORNING...AS THE UPPER TROUGH AXIS TO THE STRONG STORM SYSTEM YESTERDAY HAS CROSSED THE REGION. THE CYCLONE IS NOW DEEPENING AND INTENSIFYING OVER LABRADOR /980 HPA/. SOME GUSTY WINDS ARE IMPACTING PARTS OF THE REGION WITH THE STRONG SFC PRESSURE GRADIENT BETWEEN THE DEPARTING CYCLONE...AND HIGH PRESSURE OVER THE LOWER MS RIVER VALLEY/SOUTHEAST. KALB HAD A PEAK WIND GUST OF 39 KTS /45 MPH/ BTWN 1-2 AM AND AT 5 AM. THE CORE OF THE STRONGEST WINDS AT H850 OF 40-50 KTS WILL BE OVER THE ERN HALF OF THE FCST AREA PRIOR TO 12Z. SOME GUSTS OF 30-45 MPH WILL BE POSSIBLE ESPECIALLY PRIOR TO NOON...AS THE SFC PRESSURE GRADIENT STARTS TO WEAKEN THEREAFTER. THE STRONGEST GUSTS WILL BE DUE TO THE FUNNELING EFFECT DOWN THE MOHAWK RIVER VALLEY. THE CYCLONIC FLOW WILL CONTINUE WITH H850 TEMPS FALLING TO -18C TO -13C FROM NORTHWEST TO SOUTHEAST OVER THE FCST AREA. IN THE W/NW SOME MULTIBANDS OF LAKE EFFECT WILL CONTINUE TO BE POSSIBLE. THE LATEST HRRR SHOWS A WEAKENING OF THE ACTIVITY AROUND 12Z. THE CURRENT RADAR SHOWS SEVERAL NARROW MULTIBANDS OFF LAKE ONTARIO IMPACTING THE WRN DACKS...W-CNTRL MOHAWK...AND NRN CATSKILLS. THESE BANDS SEEM TO BE ENDURING SOME SHEAR AND DRY AIR INTRUDING. POPS WERE ADJUSTED FOR MORE SNOW SHOWERS OVER THE NRN AND ERN CATSKILLS. NONETHELESS...LOCALLY A BURST OF WIND DRIVEN SNOW IS POSSIBLE ESPECIALLY ACROSS THE WRN DACKS...W-CNTRL MOHAWK VALLEY...AND THE SRN GREENS/BERKS...DUE TO THE W/NW UPSLOPE COMPONENT. THE LAKE EFFECT ADVISORY FOR SRN HERKIMER WILL CONTINUE...IT GOES ALL THE WAY TO 7 AM TOMORROW. THE ACTIVITY MAY SLIP SOUTH OF THE ADVISORY AREA LATER TODAY BASED ON THE HRRR...BUT THE LOCAL HIRES WRF SHOWS A COUPLE OF BANDS IN THE 300 DEG TRAJECTORY BOUNDARY LAYER FLOW...AND ONE DOES GO THROUGH SRN HERKIMER...MONTGOMERY AND WRN FULTON COUNTIES INTO THE PM. BOTH FORMS OF HIGH RESOLUTION GUIDANCE SHOWS THE BANDS WEAKENING IN THE AFTERNOON...UNTIL A SHORT-WAVE ARRIVES TONIGHT FROM THE GREAT LAKES REGION. COLD...WINDY...AND PARTLY CLOUDY CONDITIONS WILL PERSIST TODAY FOR A LARGE PORTION OF THE AREA WITH HIGH TEMPS ABOUT 15 DEGREES BELOW NORMAL. EXPECT HIGHS IN THE TEENS AND L20S OVER THE SRN DACKS...SRN GREENS...AND ERN CATSKILLS. MID AND U20S WILL BE COMMON ELSEWHERE...EXCEPT FOR A FEW L30S IN THE MID HUDSON VALLEY...SRN TACONICS...AND LITCHFIELD CTY CT. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... TONIGHT...THE AFOREMENTIONED IMPULSE IN THE CYCLONIC FLOW WILL MOVE ACROSS THE REGION WITH SOME LAKE ENHANCED SNOW SHOWERS AND FLURRIES. THE BOUNDARY LAYER FLOW SHOULD BACK INITIALLY FOR A 270-280 DEG TRAJECTORY FOR PERHAPS THE CNTRL PORTION OF HERKIMER AND SW HAMILTON COS TO GET A LITTLE SNOW...BEFORE VEERING AGAIN INTO THE WRN-CNTRL MOHAWK VALLEY AND NRN CATSKILLS. ANOTHER FEW INCHES OF SNOW WILL BE POSSIBLE IN THESE LOCATIONS...AND A 3-6" TALLY FOR THE ADVISORY AREA LOOKS FINE. CLOUDS WILL INCREASE FOR THE BULK OF THE REGION WITH PERHAPS SOME FLURRIES FROM THE CAPITAL REGION EASTWARD. THE MID LEVEL VORT MAX/SHORT-WAVE SHOULD MOVE DOWNSTREAM BY FRI MORNING WITH THE INVERSION HEIGHTS STARTING TO LOWER TO SQUASH THE LAKE EFFECT ACTIVITY. A COLD NIGHT IS EXPECTED WITH MAINLY TEENS FOR LOWS FOR THE REGION...EXCEPT SOME SINGLE DIGITS FOR THE SRN ADIRONDACK REGION....AND SRN GREENS. FRIDAY...THE BIG SHOPPING DAY LOOKS MAINLY DRY WITH THE LAKE EFFECT SNOW SHOWERS AND FLURRIES DWINDLING WITH A STRONG SFC ANTICYCLONE RIDGING IN FROM SE ONTARIO...AND THE ERN GREAT LAKES REGION. THE BEST CHC OF A STRAY SNOW SHOWER WILL BE OVER THE W-CNTRL MOHAWK RIVER VALLEY...AND NRN CATSKILLS. H850 TEMPS WILL STILL BE A LITTLE BELOW NORMAL WITH -12C TO -15C READINGS. MAX TEMPS MAY BE A SMIDGE WARMER THAN THANKSGIVING WITH HIGHS IN THE U20S TO L30S IN THE VALLEYS /EXCEPT THE MID HUDSON RIVER VALLEY WHERE A FEW M30S WILL BE POSSIBLE/...AND MAINLY LOWER TO M20S OVER THE HIGH PEAKS. FRIDAY NIGHT...A VERY COLD NIGHT WILL BE ON TAP...AS THE SFC HIGH STRENGTHENS TO 1043 HPA OVER ERN NY ON THE NAM40. MOSTLY CLEAR/CLEAR SKIES WITH LIGHT TO CALM WINDS WILL YIELD IDEAL RADIATIONAL COOLING CONDITIONS WITH LOWS FORECASTED CLOSER TO THE NAM MOS GUIDANCE. LOWS 5 ABOVE TO 5 BELOW ZERO OVER THE LAKE GEORGE REGION...AND SRN DACKS. SINGLE DIGITS IN THE MOHAWK RIVER VALLEY...NRN CATSKILLS...HELDERBERGS...SRN VT...N-CNTRL BERKS...AND NRN SARATOGA REGION...LOWER TEENS IN THE CAPITAL DISTRICT..TACONICS...SRN BERKS...MID HUDSON VALLEY...AND NW CT. SATURDAY-SATURDAY NIGHT...DRY WEATHER WILL START THE WEEKEND WITH TEMPS STILL RUNNING BELOW NORMAL BY 10-15 DEGS. THE SFC HIGH MOVES DOWN STREAM OVER NRN NEW ENGLAND AND THE GULF OF MAINE. A LIGHT S/SE BREEZE BEGINS LATE IN THE DAY. MOSTLY SUNNY SKIES EARLY ON WILL GIVE WAY TO INCREASE MID AND HIGH CLOUDS IN THE WARM ADVECTION REGIME. A CLIPPER LOW WILL BE APPROACHING FROM THE NRN GREAT LAKES REGION...AND S-CNTRL ONTARIO. THE TIMING IS VARIABLE ON THE GUIDANCE...AND SLIGHT CHC OF SNOW SHOWERS WAS PLACED IN THE GRIDS AFTER MIDNIGHT. LOWS SATURDAY WILL BE MUCH WARMER THAN THE PREVIOUS NIGHTS WITH TEENS TO THE NORTH OF THE MOHAWK RIVER VALLEY/CAPITAL REGION...AND LOWER TO M20S TO THE SOUTH. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... MUCH OF THE LONG TERM PERIOD IS EXPECTED TO BE DRY WITH THE MAIN FEATURE FOR EARLY NEXT WEEK BEING A COASTAL LOW WHICH WOULD POTENTIALLY IMPACT THE FA IN THE TUESDAY TO TUESDAY NIGHT TIME FRAME. SUNDAY AND SUNDAY NIGHT...A CLIPPER TYPE SYSTEM WITH LIMITED MOISTURE IS EXPECTED TO IMPACT THE FA AS IT TRACKS ACRS SRN CANADA AND NRN NEW ENGLAND. HIGHS ON SUNDAY ARE EXPECTED TO RANGE FROM THE LOWER 30S NORTHWEST TO MID 40S SOUTHEAST WITH LOWS SUNDAY NIGHT GENERALLY IN THE 20S TO AROUND 30. MONDAY AND MONDAY NIGHT...LOOK TO BE DRY AS HIGH PRESSURE BRIEFLY BUILDS BACK INTO THE FA. HIGHS ARE EXPECTED TO BE IN THE 30S TO AROUND 40 WITH SOME UPPER 20S ACROSS THE WESTERN ADIRONDACKS. LOWS ARE EXPECTED TO BE IN THE MID TEENS TO UPPER 20S. TUESDAY AND TUESDAY NIGHT...A COASTAL LOW MAY IMPACT THE FA AS IT WORKS NORTHWARD UP THE EASTERN SEABOARD TUESDAY AND INTO THE GULF OF MAINE BY LATE TUESDAY NIGHT. TOO FAR OUT TO GET VERY SPECIFIC AT THIS POINT IN TIME...BUT WILL INCLUDE CHANCE POPS IN THE FORECAST FOR NOW. EXPECT HIGHS ON TUESDAY IN THE UPPER 20S TO UPPER 30S WITH LOWS TUESDAY NIGHT IN THE MID TEENS TO MID 20S. WEDNESDAY...AT THIS TIME LOOKS TO BE A DRY DAY AS COASTAL SYSTEM DEPARTS EAST OF THE CANADIAN MARITIMES AND A RIDGE OF HIGH PRESSURE BUILDS SOUTHEAST FROM NORTH OF THE UPPER GREAT LAKES. EXPECT HIGHS ON WEDNESDAY TO BE IN THE MID 20S TO UPPER 30S. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... MAINLY VFR CONDITIONS ARE EXPECTED AT THE TAF SITES THROUGH THE END OF THE TAF PERIOD ENDING AT 12Z FRI. SKIES WILL GENERALLY BE SCT025-040 SCT100 TODAY EXCEPT FOR BRIEFLY OVC025 AT KPSF. SKIES WILL BECOME SKC THIS EVENING. THE WEST-NORTHWEST WINDS WILL REMAIN STRONG AS A STRONG PRESSURE GRADIENT REMAINS ACRS THE REGION. WIND GUSTS WILL INCREASE TO OVER 30 KTS AT TIMES. THE WINDS WILL GRADUALLY DIMINISH THU EVENING BECOMING LIGHT AND VARIABLE AFTER DARK. OUTLOOK... FRIDAY TO SATURDAY: NO OPERATIONAL IMPACT. NO SIG WX. SATURDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. SUNDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN. SUNDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. MONDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN. && .HYDROLOGY... THE RIVERS HAVE CRESTED...AND FLOWS ARE STARTING TO DECREASE WITH THE COLDER TEMPS. THE TREND THE NEXT 5 DAYS ARE FOR FLOWS TO DECREASE IN THE COLD AND DRY AIR MASS INTO THE HOLIDAY WEEKEND. ANY PRECIP WILL BE IN THE FORM OF SNOW SHOWERS PREDOMINANTLY WEST OF THE HUDSON RIVER VALLEY TODAY INTO FRIDAY. A CLIPPER LOW MAY BRING SOME SCT SNOW SHOWERS TO THE REGION TO CLOSE THE WEEKEND WITH VERY LIGHT QPF. MOST LOCATIONS OUTSIDE OF THE FAVORED LAKE EFFECT AREAS ARE NOT EXPECTED TO RECEIVE A TENTH OF AN INCH OF LIQUID EQUIVALENT THE NEXT 5 DAYS. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST FRIDAY FOR NYZ038. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...WASULA SHORT TERM...WASULA LONG TERM...11 AVIATION...11 HYDROLOGY...JPV/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
609 AM EST THU NOV 28 2013 .SYNOPSIS... LOW PRESSURE WILL CONTINUE TO DEEPEN AND INTENSIFY AS IT MOVES FURTHER NORTHEAST INTO THE CANADIAN MARITIMES...AS HIGH PRESSURE WILL ATTEMPT TO BUILD IN FROM THE SOUTHEAST. BLUSTERY AND COLD CONDITIONS ARE EXPECTED FOR THANKSGIVING TODAY WITH SOME LAKE EFFECT SNOW SHOWERS WEST OF THE GREATER CAPITAL REGION. A WEAK DISTURBANCE WILL BRING SOME LAKE EFFECT SNOW SHOWERS AND FLURRIES TONIGHT INTO EARLY FRIDAY MAINLY WEST OF THE HUDSON RIVER VALLEY...BEFORE HIGH PRESSURE BUILDS IN LATE FRIDAY INTO THE FIRST HALF OF THE WEEKEND WITH DRY WEATHER AND BELOW NORMAL TEMPERATURES TO CLOSE NOVEMBER. && .NEAR TERM /THROUGH TONIGHT/... AS OF 330 AM EST...HAPPY THANKSGIVING EVERYONE ! BLUSTERY AND COLD CONDITIONS GREET ERN NY AND WRN NEW ENGLAND THIS MORNING...AS THE UPPER TROUGH AXIS TO THE STRONG STORM SYSTEM YESTERDAY HAS CROSSED THE REGION. THE CYCLONE IS NOW DEEPENING AND INTENSIFYING OVER NEW BRUNSWICK /984 HPA/. SOME GUSTY WINDS ARE IMPACTING PARTS OF THE REGION WITH THE STRONG SFC PRESSURE GRADIENT BETWEEN THE DEPARTING CYCLONE...AND HIGH PRESSURE OVER THE LOWER MS RIVER VALLEY/SOUTHEAST. KALB HAD A PEAK WIND GUST OF 39 KTS /45 MPH/ BTWN 1-2 AM. THE CORE OF THE STRONGEST WINDS AT H850 OF 40-50 KTS WILL BE OVER THE ERN HALF OF THE FCST AREA PRIOR TO 12Z. SOME GUSTS OF 30-40 MPH WILL BE POSSIBLE ESPECIALLY PRIOR TO NOON...AS THE SFC PRESSURE GRADIENT STARTS TO WEAKEN THEREAFTER. THE CYCLONIC FLOW WILL CONTINUE WITH H850 TEMPS FALLING TO -18C TO -13C FROM NORTHWEST TO SOUTHEAST OVER THE FCST AREA. IN THE W/NW SOME MULTIBANDS OF LAKE EFFECT WILL CONTINUE TO BE POSSIBLE. THE LATEST HRRR SHOWS A WEAKENING OF THE ACTIVITY TOWARDS 12Z. THE CURRENT RADAR SHOWS SEVERAL NARROW MULTIBANDS OFF LAKE ONTARIO IMPACTING THE WRN DACKS...W-CNTRL MOHAWK...AND NRN CATSKILLS. THESE BANDS SEEM TO BE ENDURING SOME SHEAR AND DRY AIR INTRUDING. NONETHELESS...LOCALLY A BURST OF WIND DRIVEN SNOW IS POSSIBLE ESPECIALLY ACROSS THE WRN DACKS...W-CNTRL MOHAWK VALLEY...AND THE SRN GREENS/BERKS...DUE TO THE W/NW UPSLOPE COMPONENT. THE LAKE EFFECT ADVISORY FOR SRN HERKIMER WILL CONTINUE...IT GOES ALL THE WAY TO 7 AM TOMORROW. THE ACTIVITY MAY SLIP SOUTH OF THE ADVISORY AREA LATER TODAY BASED ON THE HRRR...BUT THE LOCAL HIRES WRF SHOWS A COUPLE OF BANDS IN THE 300 DEG TRAJECTORY BOUNDARY LAYER FLOW...AND ONE DOES GO THROUGH SRN HERKIMER...MONTGOMERY AND WRN FULTON COUNTIES INTO THE PM. BOTH FORMS OF HIGH RESOLUTION GUIDANCE SHOWS THE BANDS WEAKENING IN THE AFTERNOON...UNTIL A SHORT-WAVE ARRIVES TONIGHT FROM THE GREAT LAKES REGION. COLD...WINDY...AND PARTLY CLOUDY CONDITIONS WILL PERSIST TODAY FOR A LARGE PORTION OF THE AREA WITH HIGH TEMPS ABOUT 15 DEGREES BELOW NORMAL. EXPECT HIGHS IN THE TEENS AND L20S OVER THE SRN DACKS...SRN GREENS...AND ERN CATSKILLS. MID AND U20S WILL BE COMMON ELSEWHERE...EXCEPT FOR A FEW L30S IN THE MID HUDSON VALLEY...SRN TACONICS...AND LITCHFIELD CTY CT. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... TONIGHT...THE AFOREMENTIONED IMPULSE IN THE CYCLONIC FLOW WILL MOVE ACROSS THE REGION WITH SOME LAKE ENHANCED SNOW SHOWERS AND FLURRIES. THE BOUNDARY LAYER FLOW SHOULD BACK INITIALLY FOR A 270-280 DEG TRAJECTORY FOR PERHAPS THE CNTRL PORTION OF HERKIMER AND SW HAMILTON COS TO GET A LITTLE SNOW...BEFORE VEERING AGAIN INTO THE WRN-CNTRL MOHAWK VALLEY AND NRN CATSKILLS. ANOTHER FEW INCHES OF SNOW WILL BE POSSIBLE IN THESE LOCATIONS...AND A 3-6" TALLY FOR THE ADVISORY AREA LOOKS FINE. CLOUDS WILL INCREASE FOR THE BULK OF THE REGION WITH PERHAPS SOME FLURRIES FROM THE CAPITAL REGION EASTWARD. THE MID LEVEL VORT MAX/SHORT-WAVE SHOULD MOVE DOWNSTREAM BY FRI MORNING WITH THE INVERSION HEIGHTS STARTING TO LOWER TO SQUASH THE LAKE EFFECT ACTIVITY. A COLD NIGHT IS EXPECTED WITH MAINLY TEENS FOR LOWS FOR THE REGION...EXCEPT SOME SINGLE DIGITS FOR THE SRN ADIRONDACK REGION....AND SRN GREENS. FRIDAY...THE BIG SHOPPING DAY LOOKS MAINLY DRY WITH THE LAKE EFFECT SNOW SHOWERS AND FLURRIES DWINDLING WITH A STRONG SFC ANTICYCLONE RIDGING IN FROM SE ONTARIO...AND THE ERN GREAT LAKES REGION. THE BEST CHC OF A STRAY SNOW SHOWER WILL BE OVER THE W-CNTRL MOHAWK RIVER VALLEY...AND NRN CATSKILLS. H850 TEMPS WILL STILL BE A LITTLE BELOW NORMAL WITH -12C TO -15C READINGS. MAX TEMPS MAY BE A SMIDGE WARMER THAN THANKSGIVING WITH HIGHS IN THE U20S TO L30S IN THE VALLEYS /EXCEPT THE MID HUDSON RIVER VALLEY WHERE A FEW M30S WILL BE POSSIBLE/...AND MAINLY LOWER TO M20S OVER THE HIGH PEAKS. FRIDAY NIGHT...A VERY COLD NIGHT WILL BE ON TAP...AS THE SFC HIGH STRENGTHENS TO 1043 HPA OVER ERN NY ON THE NAM40. MOSTLY CLEAR/CLEAR SKIES WITH LIGHT TO CALM WINDS WILL YIELD IDEAL RADIATIONAL COOLING CONDITIONS WITH LOWS FORECASTED CLOSER TO THE NAM MOS GUIDANCE. LOWS 5 ABOVE TO 5 BELOW ZERO OVER THE LAKE GEORGE REGION...AND SRN DACKS. SINGLE DIGITS IN THE MOHAWK RIVER VALLEY...NRN CATSKILLS...HELDERBERGS...SRN VT...N-CNTRL BERKS...AND NRN SARATOGA REGION...LOWER TEENS IN THE CAPITAL DISTRICT..TACONICS...SRN BERKS...MID HUDSON VALLEY...AND NW CT. SATURDAY-SATURDAY NIGHT...DRY WEATHER WILL START THE WEEKEND WITH TEMPS STILL RUNNING BELOW NORMAL BY 10-15 DEGS. THE SFC HIGH MOVES DOWN STREAM OVER NRN NEW ENGLAND AND THE GULF OF MAINE. A LIGHT S/SE BREEZE BEGINS LATE IN THE DAY. MOSTLY SUNNY SKIES EARLY ON WILL GIVE WAY TO INCREASE MID AND HIGH CLOUDS IN THE WARM ADVECTION REGIME. A CLIPPER LOW WILL BE APPROACHING FROM THE NRN GREAT LAKES REGION...AND S-CNTRL ONTARIO. THE TIMING IS VARIABLE ON THE GUIDANCE...AND SLIGHT CHC OF SNOW SHOWERS WAS PLACED IN THE GRIDS AFTER MIDNIGHT. LOWS SATURDAY WILL BE MUCH WARMER THAN THE PREVIOUS NIGHTS WITH TEENS TO THE NORTH OF THE MOHAWK RIVER VALLEY/CAPITAL REGION...AND LOWER TO M20S TO THE SOUTH. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... MUCH OF THE LONG TERM PERIOD IS EXPECTED TO BE DRY WITH THE MAIN FEATURE FOR EARLY NEXT WEEK BEING A COASTAL LOW WHICH WOULD POTENTIALLY IMPACT THE FA IN THE TUESDAY TO TUESDAY NIGHT TIME FRAME. SUNDAY AND SUNDAY NIGHT...A CLIPPER TYPE SYSTEM WITH LIMITED MOISTURE IS EXPECTED TO IMPACT THE FA AS IT TRACKS ACRS SRN CANADA AND NRN NEW ENGLAND. HIGHS ON SUNDAY ARE EXPECTED TO RANGE FROM THE LOWER 30S NORTHWEST TO MID 40S SOUTHEAST WITH LOWS SUNDAY NIGHT GENERALLY IN THE 20S TO AROUND 30. MONDAY AND MONDAY NIGHT...LOOK TO BE DRY AS HIGH PRESSURE BRIEFLY BUILDS BACK INTO THE FA. HIGHS ARE EXPECTED TO BE IN THE 30S TO AROUND 40 WITH SOME UPPER 20S ACROSS THE WESTERN ADIRONDACKS. LOWS ARE EXPECTED TO BE IN THE MID TEENS TO UPPER 20S. TUESDAY AND TUESDAY NIGHT...A COASTAL LOW MAY IMPACT THE FA AS IT WORKS NORTHWARD UP THE EASTERN SEABOARD TUESDAY AND INTO THE GULF OF MAINE BY LATE TUESDAY NIGHT. TOO FAR OUT TO GET VERY SPECIFIC AT THIS POINT IN TIME...BUT WILL INCLUDE CHANCE POPS IN THE FORECAST FOR NOW. EXPECT HIGHS ON TUESDAY IN THE UPPER 20S TO UPPER 30S WITH LOWS TUESDAY NIGHT IN THE MID TEENS TO MID 20S. WEDNESDAY...AT THIS TIME LOOKS TO BE A DRY DAY AS COASTAL SYSTEM DEPARTS EAST OF THE CANADIAN MARITIMES AND A RIDGE OF HIGH PRESSURE BUILDS SOUTHEAST FROM NORTH OF THE UPPER GREAT LAKES. EXPECT HIGHS ON WEDNESDAY TO BE IN THE MID 20S TO UPPER 30S. && .AVIATION /11Z THURSDAY THROUGH MONDAY/... MAINLY VFR CONDITIONS ARE EXPECTED AT THE TAF SITES THROUGH THE END OF THE TAF PERIOD ENDING AT 12Z FRI. SKIES WILL GENERALLY BE SCT025-040 SCT100 TODAY EXCEPT FOR BRIEFLY OVC025 AT KPSF. SKIES WILL BECOME SKC THIS EVENING. THE WEST-NORTHWEST WINDS WILL REMAIN STRONG AS A STRONG PRESSURE GRADIENT REMAINS ACRS THE REGION. WIND GUSTS WILL INCREASE TO OVER 30 KTS AT TIMES. THE WINDS WILL GRADUALLY DIMINISH THU EVENING BECOMING LIGHT AND VARIABLE AFTER DARK. OUTLOOK... THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. FRIDAY TO SATURDAY: NO OPERATIONAL IMPACT. NO SIG WX. SATURDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. SUNDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN. SUNDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. MONDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN. && .HYDROLOGY... THE RIVERS HAVE CRESTED...AND FLOWS ARE STARTING TO DECREASE WITH THE COLDER TEMPS. THE TREND THE NEXT 5 DAYS ARE FOR FLOWS TO DECREASE IN THE COLD AND DRY AIR MASS INTO THE HOLIDAY WEEKEND. ANY PRECIP WILL BE IN THE FORM OF SNOW SHOWERS PREDOMINANTLY WEST OF THE HUDSON RIVER VALLEY TODAY INTO FRIDAY. A CLIPPER LOW MAY BRING SOME SCT SNOW SHOWERS TO THE REGION TO CLOSE THE WEEKEND WITH VERY LIGHT QPF. MOST LOCATIONS OUTSIDE OF THE FAVORED LAKE EFFECT AREAS ARE NOT EXPECTED TO RECEIVE A TENTH OF AN INCH OF LIQUID EQUIVALENT THE NEXT 5 DAYS. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST FRIDAY FOR NYZ038. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...WASULA SHORT TERM...WASULA LONG TERM...11 AVIATION...11 HYDROLOGY...JPV/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
331 AM EST THU NOV 28 2013 .SYNOPSIS... LOW PRESSURE WILL CONTINUE TO DEEPEN AND INTENSIFY AS IT MOVES FURTHER NORTHEAST INTO THE CANADIAN MARITIMES...AS HIGH PRESSURE WILL ATTEMPT TO BUILD IN FROM THE SOUTHEAST. BLUSTERY AND COLD CONDITIONS ARE EXPECTED FOR THANKSGIVING TODAY WITH SOME LAKE EFFECT SNOW SHOWERS WEST OF THE GREATER CAPITAL REGION. A WEAK DISTURBANCE WILL BRING SOME LAKE EFFECT SNOW SHOWERS AND FLURRIES TONIGHT INTO EARLY FRIDAY MAINLY WEST OF THE HUDSON RIVER VALLEY...BEFORE HIGH PRESSURE BUILDS IN LATE FRIDAY INTO THE FIRST HALF OF THE WEEKEND WITH DRY WEATHER AND BELOW NORMAL TEMPERATURES TO CLOSE NOVEMBER. && .NEAR TERM /THROUGH TODAY/... AS OF 330 AM EST...HAPPY THANKSGIVING EVERYONE ! BLUSTERY AND COLD CONDITIONS GREET ERN NY AND WRN NEW ENGLAND THIS MORNING...AS THE UPPER TROUGH AXIS TO THE STRONG STORM SYSTEM YESTERDAY HAS CROSSED THE REGION. THE CYCLONE IS NOW DEEPENING AND INTENSIFYING OVER NEW BRUNSWICK /984 HPA/. SOME GUSTY WINDS ARE IMPACTING PARTS OF THE REGION WITH THE STRONG SFC PRESSURE GRADIENT BETWEEN THE DEPARTING CYCLONE...AND HIGH PRESSURE OVER THE LOWER MS RIVER VALLEY/SOUTHEAST. KALB HAD A PEAK WIND GUST OF 39 KTS /45 MPH/ BTWN 1-2 AM. THE CORE OF THE STRONGEST WINDS AT H850 OF 40-50 KTS WILL BE OVER THE ERN HALF OF THE FCST AREA PRIOR TO 12Z. SOME GUSTS OF 30-40 MPH WILL BE POSSIBLE ESPECIALLY PRIOR TO NOON...AS THE SFC PRESSURE GRADIENT STARTS TO WEAKEN THEREAFTER. THE CYCLONIC FLOW WILL CONTINUE WITH H850 TEMPS FALLING TO -18C TO -13C FROM NORTHWEST TO SOUTHEAST OVER THE FCST AREA. IN THE W/NW SOME MULTIBANDS OF LAKE EFFECT WILL CONTINUE TO BE POSSIBLE. THE LATEST HRRR SHOWS A WEAKENING OF THE ACTIVITY TOWARDS 12Z. THE CURRENT RADAR SHOWS SEVERAL NARROW MULTIBANDS OFF LAKE ONTARIO IMPACTING THE WRN DACKS...W-CNTRL MOHAWK...AND NRN CATSKILLS. THESE BANDS SEEM TO BE ENDURING SOME SHEAR AND DRY AIR INTRUDING. NONETHELESS...LOCALLY A BURST OF WIND DRIVEN SNOW IS POSSIBLE ESPECIALLY ACROSS THE WRN DACKS...W-CNTRL MOHAWK VALLEY...AND THE SRN GREENS/BERKS...DUE TO THE W/NW UPSLOPE COMPONENT. THE LAKE EFFECT ADVISORY FOR SRN HERKIMER WILL CONTINUE...IT GOES ALL THE WAY TO 7 AM TOMORROW. THE ACTIVITY MAY SLIP SOUTH OF THE ADVISORY AREA LATER TODAY BASED ON THE HRRR...BUT THE LOCAL HIRES WRF SHOWS A COUPLE OF BANDS IN THE 300 DEG TRAJECTORY BOUNDARY LAYER FLOW...AND ONE DOES GO THROUGH SRN HERKIMER...MONTGOMERY AND WRN FULTON COUNTIES INTO THE PM. BOTH FORMS OF HIGH RESOLUTION GUIDANCE SHOWS THE BANDS WEAKENING IN THE AFTERNOON...UNTIL A SHORT-WAVE ARRIVES TONIGHT FROM THE GREAT LAKES REGION. COLD...WINDY...AND PARTLY CLOUDY CONDITIONS WILL PERSIST TODAY FOR A LARGE PORTION OF THE AREA WITH HIGH TEMPS ABOUT 15 DEGREES BELOW NORMAL. EXPECT HIGHS IN THE TEENS AND L20S OVER THE SRN DACKS...SRN GREENS...AND ERN CATSKILLS. MID AND U20S WILL BE COMMON ELSEWHERE...EXCEPT FOR A FEW L30S IN THE MID HUDSON VALLEY...SRN TACONICS...AND LITCHFIELD CTY CT. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... TONIGHT...THE AFOREMENTIONED IMPULSE IN THE CYCLONIC FLOW WILL MOVE ACROSS THE REGION WITH SOME LAKE ENHANCED SNOW SHOWERS AND FLURRIES. THE BOUNDARY LAYER FLOW SHOULD BACK INITIALLY FOR A 270-280 DEG TRAJECTORY FOR PERHAPS THE CNTRL PORTION OF HERKIMER AND SW HAMILTON COS TO GET A LITTLE SNOW...BEFORE VEERING AGAIN INTO THE WRN-CNTRL MOHAWK VALLEY AND NRN CATSKILLS. ANOTHER FEW INCHES OF SNOW WILL BE POSSIBLE IN THESE LOCATIONS...AND A 3-6" TALLY FOR THE ADVISORY AREA LOOKS FINE. CLOUDS WILL INCREASE FOR THE BULK OF THE REGION WITH PERHAPS SOME FLURRIES FROM THE CAPITAL REGION EASTWARD. THE MID LEVEL VORT MAX/SHORT-WAVE SHOULD MOVE DOWNSTREAM BY FRI MORNING WITH THE INVERSION HEIGHTS STARTING TO LOWER TO SQUASH THE LAKE EFFECT ACTIVITY. A COLD NIGHT IS EXPECTED WITH MAINLY TEENS FOR LOWS FOR THE REGION...EXCEPT SOME SINGLE DIGITS FOR THE SRN ADIRONDACK REGION....AND SRN GREENS. FRIDAY...THE BIG SHOPPING DAY LOOKS MAINLY DRY WITH THE LAKE EFFECT SNOW SHOWERS AND FLURRIES DWINDLING WITH A STRONG SFC ANTICYCLONE RIDGING IN FROM SE ONTARIO...AND THE ERN GREAT LAKES REGION. THE BEST CHC OF A STRAY SNOW SHOWER WILL BE OVER THE W-CNTRL MOHAWK RIVER VALLEY...AND NRN CATSKILLS. H850 TEMPS WILL STILL BE A LITTLE BELOW NORMAL WITH -12C TO -15C READINGS. MAX TEMPS MAY BE A SMIDGE WARMER THAN THANKSGIVING WITH HIGHS IN THE U20S TO L30S IN THE VALLEYS /EXCEPT THE MID HUDSON RIVER VALLEY WHERE A FEW M30S WILL BE POSSIBLE/...AND MAINLY LOWER TO M20S OVER THE HIGH PEAKS. FRIDAY NIGHT...A VERY COLD NIGHT WILL BE ON TAP...AS THE SFC HIGH STRENGTHENS TO 1043 HPA OVER ERN NY ON THE NAM40. MOSTLY CLEAR/CLEAR SKIES WITH LIGHT TO CALM WINDS WILL YIELD IDEAL RADIATIONAL COOLING CONDITIONS WITH LOWS FORECASTED CLOSER TO THE NAM MOS GUIDANCE. LOWS 5 ABOVE TO 5 BELOW ZERO OVER THE LAKE GEORGE REGION...AND SRN DACKS. SINGLE DIGITS IN THE MOHAWK RIVER VALLEY...NRN CATSKILLS...HELDERBERGS...SRN VT...N-CNTRL BERKS...AND NRN SARATOGA REGION...LOWER TEENS IN THE CAPITAL DISTRICT..TACONICS...SRN BERKS...MID HUDSON VALLEY...AND NW CT. SATURDAY-SATURDAY NIGHT...DRY WEATHER WILL START THE WEEKEND WITH TEMPS STILL RUNNING BELOW NORMAL BY 10-15 DEGS. THE SFC HIGH MOVES DOWN STREAM OVER NRN NEW ENGLAND AND THE GULF OF MAINE. A LIGHT S/SE BREEZE BEGINS LATE IN THE DAY. MOSTLY SUNNY SKIES EARLY ON WILL GIVE WAY TO INCREASE MID AND HIGH CLOUDS IN THE WARM ADVECTION REGIME. A CLIPPER LOW WILL BE APPROACHING FROM THE NRN GREAT LAKES REGION...AND S-CNTRL ONTARIO. THE TIMING IS VARIABLE ON THE GUIDANCE...AND SLIGHT CHC OF SNOW SHOWERS WAS PLACED IN THE GRIDS AFTER MIDNIGHT. LOWS SATURDAY WILL BE MUCH WARMER THAN THE PREVIOUS NIGHTS WITH TEENS TO THE NORTH OF THE MOHAWK RIVER VALLEY/CAPITAL REGION...AND LOWER TO M20S TO THE SOUTH. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... MUCH OF THE LONG TERM PERIOD IS EXPECTED TO BE DRY WITH THE MAIN FEATURE FOR EARLY NEXT WEEK BEING A COASTAL LOW WHICH WOULD POTENTIALLY IMPACT THE FA IN THE TUESDAY TO TUESDAY NIGHT TIME FRAME. SUNDAY AND SUNDAY NIGHT...A CLIPPER TYPE SYSTEM WITH LIMITED MOISTURE IS EXPECTED TO IMPACT THE FA AS IT TRACKS ACRS SRN CANADA AND NRN NEW ENGLAND. HIGHS ON SUNDAY ARE EXPECTED TO RANGE FROM THE LOWER 30S NORTHWEST TO MID 40S SOUTHEAST WITH LOWS SUNDAY NIGHT GENERALLY IN THE 20S TO AROUND 30. MONDAY AND MONDAY NIGHT...LOOK TO BE DRY AS HIGH PRESSURE BRIEFLY BUILDS BACK INTO THE FA. HIGHS ARE EXPECTED TO BE IN THE 30S TO AROUND 40 WITH SOME UPPER 20S ACROSS THE WESTERN ADIRONDACKS. LOWS ARE EXPECTED TO BE IN THE MID TEENS TO UPPER 20S. TUESDAY AND TUESDAY NIGHT...A COASTAL LOW MAY IMPACT THE FA AS IT WORKS NORTHWARD UP THE EASTERN SEABOARD TUESDAY AND INTO THE GULF OF MAINE BY LATE TUESDAY NIGHT. TOO FAR OUT TO GET VERY SPECIFIC AT THIS POINT IN TIME...BUT WILL INCLUDE CHANCE POPS IN THE FORECAST FOR NOW. EXPECT HIGHS ON TUESDAY IN THE UPPER 20S TO UPPER 30S WITH LOWS TUESDAY NIGHT IN THE MID TEENS TO MID 20S. WEDNESDAY...AT THIS TIME LOOKS TO BE A DRY DAY AS COASTAL SYSTEM DEPARTS EAST OF THE CANADIAN MARITIMES AND A RIDGE OF HIGH PRESSURE BUILDS SOUTHEAST FROM NORTH OF THE UPPER GREAT LAKES. EXPECT HIGHS ON WEDNESDAY TO BE IN THE MID 20S TO UPPER 30S. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... MAINLY VFR CONDITIONS ARE EXPECTED AT THE TAF SITES THROUGH THE END OF THE TAF PERIOD ENDING AT 06Z FRI. SKIES WILL GENERALLY BE OVC035-080 THROUGH THE OVERNIGHT AND THEN SCT025-035 SCT100 ON THURSDAY AND THEN BECOME SKC THU EVENING. THE WEST-NORTHWEST WINDS TOO WILL BE ON THE INCREASE AS PRESSURE GRADIENT REMAINS TIGHT. AS MIXING LAYER HEIGHTS INCREASE DURING THURSDAY...WIND GUSTS WILL INCREASE TO AROUND 30 KTS. THE WINDS WILL GRADUALLY DIMINISH THU EVENING BECOMING LIGHT AND VARIABLE AFTER DARK. OUTLOOK... THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. FRIDAY TO SATURDAY: NO OPERATIONAL IMPACT. NO SIG WX. SATURDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. SUNDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN. SUNDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. MONDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN. && .HYDROLOGY... THE RIVERS HAVE CRESTED...AND FLOWS ARE STARTING TO DECREASE WITH THE COLDER TEMPS. THE TREND THE NEXT 5 DAYS ARE FOR FLOWS TO DECREASE IN THE COLD AND DRY AIR MASS INTO THE HOLIDAY WEEKEND. ANY PRECIP WILL BE IN THE FORM OF SNOW SHOWERS PREDOMINANTLY WEST OF THE HUDSON RIVER VALLEY TODAY INTO FRIDAY. A CLIPPER LOW MAY BRING SOME SCT SNOW SHOWERS TO THE REGION TO CLOSE THE WEEKEND WITH VERY LIGHT QPF. MOST LOCATIONS OUTSIDE OF THE FAVORED LAKE EFFECT AREAS ARE NOT EXPECTED TO RECEIVE A TENTH OF AN INCH OF LIQUID EQUIVALENT THE NEXT 5 DAYS. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST FRIDAY FOR NYZ038. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...WASULA SHORT TERM...WASULA LONG TERM...11 AVIATION...11 HYDROLOGY...JPV/WASULA
AREA FORECAST DISCUSSION...UPDATED
NWS MIAMI FL
1224 PM EST THU NOV 28 2013 .AVIATION... THE WINDS WILL BE SWINGING TO A NORTHEAST DIRECTION EARLY THIS AFTERNOON AND REMAIN NORTHEAST THROUGH TONIGHT. THE SPEEDS WILL BE 5 TO 10 KNOTS THIS AFTERNOON INTO TONIGHT AT ALL OF THE TAF SITES...EXCEPT FOR KAPF TAF SITE WHERE THE SPEEDS WILL DROP DOWN TO 3 KNOTS AFTER 23Z TONIGHT. SOME CLOUDS FROM THE ATLANTIC WATERS WILL WORK INTO KFLL AND KPBI TAF STIES THIS AFTERNOON...BUT SHOULD REMAIN IN THE VFR CONDITIONS ALONG WITH THE VIS IN THE VFR CONDITIONS. REST OF THE TAF SITES OVER SOUTH FLORIDA WILL ALSO REMAIN IN THE VFR CONDITIONS FOR THE SKY AND VIS. && .AVIATION...54/BNB .PREV DISCUSSION... /ISSUED 951 AM EST THU NOV 28 2013/ UPDATE... OUTSIDE OF A FEW MINOR TWEAKS BASED ON THE LATEST OBSERVATIONS AROUND THE LOCAL AREA...NO MAJOR UPDATES WERE NECESSARY. THE WINDS OVER LAKE OKEECHOBEE WERE SLIGHTLY HIGHER THAN ORIGINALLY EXPECTED DUE TO STRONGER WINDS MIXING DOWN OVER THE WARMER LAKE WATERS...WHICH HAS PROMPTED A SHORT-FUSED ADVISORY. THESE WINDS SHOULD TREND DOWN THROUGH THE LATE MORNING AND AFTERNOON PERIOD AS THE GRADIENT RELAXES. THE MAIN STORY THIS MORNING HAS BEEN THE COOL TEMPERATURES...WHICH MARKS THE COOLEST MORNING OF THE SEASON FOR SOUTH FLORIDA. BRIGHTON IN NORTHERN GLADES COUNTY BRIEFLY DROPPED TO 36 DEGREES ..WHICH WAS THE COLDEST RECORDED TEMPERATURE IN OUR LOCAL AREA TODAY. ELSEWHERE...TEMPERATURES RANGED FROM THE UPPER 30S FROM THE INTERIOR AREAS (PALMDALE TO IMMOKALEE) TO THE LOWER 50S ALONG THE COAST IN MIAMI-DADE COUNTY. THE MORNING SOUNDING AT MIAMI REFLECTED THIS COOL AIR AT THE SURFACE BELOW A STRONG LOW-LEVEL INVERSION AROUND 1700 FT...THEN TOPPED WITH A SUBSTANTIAL AMOUNT OF DRY AIR ABOVE 3500 FT (PWAT OF .5"). THE LATEST RUC ANALYSIS HAS LINED UP WELL WITH THE CURRENT SYNOPTIC PATTERN AND GENERALLY INDICATES THE COLD AIR ADVECTION COMING TO AN END LATER TODAY AS THE LOW-LEVEL FLOW QUICKLY SHIFTS TO THE NORTHEAST. AFTERNOON HIGHS ARE FORECAST TO CLIMB INTO THE LOWER 70S. && .UPDATED...AG PREV DISCUSSION... /ISSUED 645 AM EST THU NOV 28 2013/ AVIATION...VFR WILL PREVAIL. SKIES WILL BE MOSTLY CLEAR AT KAPF THROUGH THE PERIOD. FOR THE EAST COAST, EXPECT SCT-BKN STRATO CU TO INCREASE LATER TODAY...AT AROUND 5K FT. BRIEF MVFR CIGS WILL CONTINUE IN MIAMI-DADE OVER THE NEXT HOUR BUT ARE EXPECTED TO IMPROVE. MOISTURE LOOKS TOO SHALLOW TO ADD ANY SHOWER MENTION. WINDS WILL PREVAIL NW AT NEAR 10 KT. GFS/NAM MOS LIKELY BRINGING WINDS OUT OF THE NE TOO QUICKLY ATLANTIC TERMINALS. HRRR LOOKS TO HAVE THE RIGHT IDEA, DELAYING NE WINDS UNTIL 18-19Z. /GREGORIA && PREV DISCUSSION... /ISSUED 406 AM EST THU NOV 28 2013/ DISCUSSION... TEMPERATURES IN THE LOW TO MID 50S ARE SEEN THIS MORNING ALONG THE EAST COAST WITH MID TO UPPER 40S ACROSS THE INTERIOR WITH BRISK NORTHERLY WINDS. WINDS SHOULD BEGIN TO VEER MORE TO THE NORTHEAST THROUGH THE DAY ALLOWING MORE OF A MARITIME INFLUENCE AND WEAK MOISTURE RETURN ACROSS THE AREA PARTICULARLY FOR THE EASTERN HALF OF THE AREA. HOWEVER...GENERALLY RAIN FREE WEATHER SHOULD PREVAIL THROUGH THE DAY. NORTHEAST FLOW SHOULD THEN PERSIST THROUGH THE WEEKEND AS HIGH PRESSURE REMAINS CENTERED JUST OFF THE CAROLINA COAST. THIS FLOW REGIME WILL ALLOW FOR A FEW SHOWERS TO STREAM ACROSS THE ATLANTIC WATERS AND INTO THE EAST COAST METRO AREAS DURING THIS TIME FRAME ALONG WITH SLIGHTLY WARMER TEMPERATURES. BY EARLY NEXT WEEK...A WEAK H5 SHORTWAVE IS FORECAST TO SURGE TO THE SOUTHEAST ACROSS THE DEEP SOUTH AND INTO NORTHERN FLORIDA. AS IT DOES...AN ASSOCIATED SURFACE LOW ACROSS THE WESTERN ATLANTIC WILL PULL TO THE NORTHEAST WRAPPING SOME DEEPER MOISTURE ACROSS THE FLORIDA PENINSULA RESULTING IN SLIGHT CHANCES FOR SHOWERS ON MONDAY. AS THE LOW CONTINUES TO MOVE ON...IT WILL SWING A COLD FRONT THROUGH THE AREA LATE MONDAY INTO TUESDAY WITH A RETURN TO DRIER CONDITIONS WITH MORE NORTHWEST TO NORTHERLY FLOW AND COOLER TEMPERATURES. MARINE... FRESH NORTH TO NORTHEASTERLY WINDS WILL PREVAIL TODAY AND THROUGH THE WEEKEND WITH HIGH PRESSURE SITUATED ACROSS THE WESTERN ATLANTIC. SEAS ACROSS THE GULF WATERS WILL BEGIN TO SUBSIDE THROUGH THE DAY AS WINDS BECOME MORE OFFSHORE. ACROSS THE ATLANTIC...SEAS SHOULD REMAIN NEAR ADVISORY LEVELS THROUGH SATURDAY BEFORE WINDS SUBSIDE SLIGHTLY. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 72 65 77 68 / - - 10 10 FORT LAUDERDALE 73 67 79 71 / - - 10 10 MIAMI 73 65 79 69 / - - 10 10 NAPLES 73 56 81 60 / - - - - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM- LAKE OKEECHOBEE-WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE TERRITORIAL WATERS OF THE BAHAMAS. SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM- WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM. GM...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM- COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM 20 TO 60 NM. && $$ DISCUSSION/MARINE/FIRE...10/CD AVIATION/RADAR...57/DG
AREA FORECAST DISCUSSION
NWS MIAMI FL
951 AM EST THU NOV 28 2013 .UPDATE... OUTSIDE OF A FEW MINOR TWEAKS BASED ON THE LATEST OBSERVATIONS AROUND THE LOCAL AREA...NO MAJOR UPDATES WERE NECESSARY. THE WINDS OVER LAKE OKEECHOBEE WERE SLIGHTLY HIGHER THAN ORIGINALLY EXPECTED DUE TO STRONGER WINDS MIXING DOWN OVER THE WARMER LAKE WATERS...WHICH HAS PROMPTED A SHORT-FUSED ADVISORY. THESE WINDS SHOULD TREND DOWN THROUGH THE LATE MORNING AND AFTERNOON PERIOD AS THE GRADIENT RELAXES. THE MAIN STORY THIS MORNING HAS BEEN THE COOL TEMPERATURES...WHICH MARKS THE COOLEST MORNING OF THE SEASON FOR SOUTH FLORIDA. BRIGHTON IN NORTHERN GLADES COUNTY BRIEFLY DROPPED TO 36 DEGREES ...WHICH WAS THE COLDEST RECORDED TEMPERATURE IN OUR LOCAL AREA TODAY. ELSEWHERE...TEMPERATURES RANGED FROM THE UPPER 30S FROM THE INTERIOR AREAS (PALMDALE TO IMMOKALEE) TO THE LOWER 50S ALONG THE COAST IN MIAMI-DADE COUNTY. THE MORNING SOUNDING AT MIAMI REFLECTED THIS COOL AIR AT THE SURFACE BELOW A STRONG LOW-LEVEL INVERSION AROUND 1700 FT...THEN TOPPED WITH A SUBSTANTIAL AMOUNT OF DRY AIR ABOVE 3500 FT (PWAT OF .5"). THE LATEST RUC ANALYSIS HAS LINED UP WELL WITH THE CURRENT SYNOPTIC PATTERN AND GENERALLY INDICATES THE COLD AIR ADVECTION COMING TO AN END LATER TODAY AS THE LOW-LEVEL FLOW QUICKLY SHIFTS TO THE NORTHEAST. AFTERNOON HIGHS ARE FORECAST TO CLIMB INTO THE LOWER 70S. AG && .PREV DISCUSSION... /ISSUED 645 AM EST THU NOV 28 2013/ AVIATION...VFR WILL PREVAIL. SKIES WILL BE MOSTLY CLEAR AT KAPF THROUGH THE PERIOD. FOR THE EAST COAST, EXPECT SCT-BKN STRATO CU TO INCREASE LATER TODAY...AT AROUND 5K FT. BRIEF MVFR CIGS WILL CONTINUE IN MIAMI-DADE OVER THE NEXT HOUR BUT ARE EXPECTED TO IMPROVE. MOISTURE LOOKS TOO SHALLOW TO ADD ANY SHOWER MENTION. WINDS WILL PREVAIL NW AT NEAR 10 KT. GFS/NAM MOS LIKELY BRINGING WINDS OUT OF THE NE TOO QUICKLY ATLANTIC TERMINALS. HRRR LOOKS TO HAVE THE RIGHT IDEA, DELAYING NE WINDS UNTIL 18-19Z. /GREGORIA PREV DISCUSSION... /ISSUED 406 AM EST THU NOV 28 2013/ DISCUSSION... TEMPERATURES IN THE LOW TO MID 50S ARE SEEN THIS MORNING ALONG THE EAST COAST WITH MID TO UPPER 40S ACROSS THE INTERIOR WITH BRISK NORTHERLY WINDS. WINDS SHOULD BEGIN TO VEER MORE TO THE NORTHEAST THROUGH THE DAY ALLOWING MORE OF A MARITIME INFLUENCE AND WEAK MOISTURE RETURN ACROSS THE AREA PARTICULARLY FOR THE EASTERN HALF OF THE AREA. HOWEVER...GENERALLY RAIN FREE WEATHER SHOULD PREVAIL THROUGH THE DAY. NORTHEAST FLOW SHOULD THEN PERSIST THROUGH THE WEEKEND AS HIGH PRESSURE REMAINS CENTERED JUST OFF THE CAROLINA COAST. THIS FLOW REGIME WILL ALLOW FOR A FEW SHOWERS TO STREAM ACROSS THE ATLANTIC WATERS AND INTO THE EAST COAST METRO AREAS DURING THIS TIME FRAME ALONG WITH SLIGHTLY WARMER TEMPERATURES. BY EARLY NEXT WEEK...A WEAK H5 SHORTWAVE IS FORECAST TO SURGE TO THE SOUTHEAST ACROSS THE DEEP SOUTH AND INTO NORTHERN FLORIDA. AS IT DOES...AN ASSOCIATED SURFACE LOW ACROSS THE WESTERN ATLANTIC WILL PULL TO THE NORTHEAST WRAPPING SOME DEEPER MOISTURE ACROSS THE FLORIDA PENINSULA RESULTING IN SLIGHT CHANCES FOR SHOWERS ON MONDAY. AS THE LOW CONTINUES TO MOVE ON...IT WILL SWING A COLD FRONT THROUGH THE AREA LATE MONDAY INTO TUESDAY WITH A RETURN TO DRIER CONDITIONS WITH MORE NORTHWEST TO NORTHERLY FLOW AND COOLER TEMPERATURES. MARINE... FRESH NORTH TO NORTHEASTERLY WINDS WILL PREVAIL TODAY AND THROUGH THE WEEKEND WITH HIGH PRESSURE SITUATED ACROSS THE WESTERN ATLANTIC. SEAS ACROSS THE GULF WATERS WILL BEGIN TO SUBSIDE THROUGH THE DAY AS WINDS BECOME MORE OFFSHORE. ACROSS THE ATLANTIC...SEAS SHOULD REMAIN NEAR ADVISORY LEVELS THROUGH SATURDAY BEFORE WINDS SUBSIDE SLIGHTLY. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 72 64 77 68 / - - 10 10 FORT LAUDERDALE 73 67 79 71 / - - 10 10 MIAMI 73 65 79 69 / - - 10 10 NAPLES 73 56 81 60 / - - - - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM- LAKE OKEECHOBEE-WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE TERRITORIAL WATERS OF THE BAHAMAS. SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM- WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM. GM...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM- COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM 20 TO 60 NM. && $$ DISCUSSION/MARINE/FIRE...85/AG AVIATION/RADAR...54/BNB
AREA FORECAST DISCUSSION
NWS MIAMI FL
645 AM EST THU NOV 28 2013 .AVIATION...VFR WILL PREVAIL. SKIES WILL BE MOSTLY CLEAR AT KAPF THROUGH THE PERIOD. FOR THE EAST COAST, EXPECT SCT-BKN STRATO CU TO INCREASE LATER TODAY...AT AROUND 5K FT. BRIEF MVFR CIGS WILL CONTINUE IN MIAMI-DADE OVER THE NEXT HOUR BUT ARE EXPECTED TO IMPROVE. MOISTURE LOOKS TOO SHALLOW TO ADD ANY SHOWER MENTION. WINDS WILL PREVAIL NW AT NEAR 10 KT. GFS/NAM MOS LIKELY BRINGING WINDS OUT OF THE NE TOO QUICKLY ATLANTIC TERMINALS. HRRR LOOKS TO HAVE THE RIGHT IDEA, DELAYING NE WINDS UNTIL 18-19Z. /GREGORIA && .PREV DISCUSSION... /ISSUED 406 AM EST THU NOV 28 2013/ DISCUSSION... TEMPERATURES IN THE LOW TO MID 50S ARE SEEN THIS MORNING ALONG THE EAST COAST WITH MID TO UPPER 40S ACROSS THE INTERIOR WITH BRISK NORTHERLY WINDS. WINDS SHOULD BEGIN TO VEER MORE TO THE NORTHEAST THROUGH THE DAY ALLOWING MORE OF A MARITIME INFLUENCE AND WEAK MOISTURE RETURN ACROSS THE AREA PARTICULARLY FOR THE EASTERN HALF OF THE AREA. HOWEVER...GENERALLY RAIN FREE WEATHER SHOULD PREVAIL THROUGH THE DAY. NORTHEAST FLOW SHOULD THEN PERSIST THROUGH THE WEEKEND AS HIGH PRESSURE REMAINS CENTERED JUST OFF THE CAROLINA COAST. THIS FLOW REGIME WILL ALLOW FOR A FEW SHOWERS TO STREAM ACROSS THE ATLANTIC WATERS AND INTO THE EAST COAST METRO AREAS DURING THIS TIME FRAME ALONG WITH SLIGHTLY WARMER TEMPERATURES. BY EARLY NEXT WEEK...A WEAK H5 SHORTWAVE IS FORECAST TO SURGE TO THE SOUTHEAST ACROSS THE DEEP SOUTH AND INTO NORTHERN FLORIDA. AS IT DOES...AN ASSOCIATED SURFACE LOW ACROSS THE WESTERN ATLANTIC WILL PULL TO THE NORTHEAST WRAPPING SOME DEEPER MOISTURE ACROSS THE FLORIDA PENINSULA RESULTING IN SLIGHT CHANCES FOR SHOWERS ON MONDAY. AS THE LOW CONTINUES TO MOVE ON...IT WILL SWING A COLD FRONT THROUGH THE AREA LATE MONDAY INTO TUESDAY WITH A RETURN TO DRIER CONDITIONS WITH MORE NORTHWEST TO NORTHERLY FLOW AND COOLER TEMPERATURES. MARINE... FRESH NORTH TO NORTHEASTERLY WINDS WILL PREVAIL TODAY AND THROUGH THE WEEKEND WITH HIGH PRESSURE SITUATED ACROSS THE WESTERN ATLANTIC. SEAS ACROSS THE GULF WATERS WILL BEGIN TO SUBSIDE THROUGH THE DAY AS WINDS BECOME MORE OFFSHORE. ACROSS THE ATLANTIC...SEAS SHOULD REMAIN NEAR ADVISORY LEVELS THROUGH SATURDAY BEFORE WINDS SUBSIDE SLIGHTLY. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 72 64 77 68 / - - 10 10 FORT LAUDERDALE 73 67 79 71 / - - 10 10 MIAMI 73 65 79 69 / - - 10 10 NAPLES 73 56 81 60 / - - - - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM- WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE TERRITORIAL WATERS OF THE BAHAMAS. SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM- WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM. GM...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM- COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM 20 TO 60 NM. && $$
AREA FORECAST DISCUSSION
NWS MIAMI FL
1243 AM EST THU NOV 28 2013 .AVIATION...VFR WILL PREVAIL. SKIES WILL BE SKC AT KAPF THROUGH THE PERIOD AND SKC-FEW050 EAST COAST THROUGH EARLY AFTERNOON, BEFORE STRATO CU MOVES ONSHORE FROM THE ATLANTIC. EXPECTING BKN050 TO PREVAIL EAST COAST TERMINALS LATE AFTERNOON AND THU NIGHT. MOISTURE LOOKS TOO SHALLOW TO ADD ANY SHOWER MENTION. WINDS WILL PREVAIL NW AT NEAR 10 KT. GFS/NAM MOS LIKELY BRINGING WINDS OUT OF THE NE TOO QUICKLY ATLANTIC TERMINALS. HRRR LOOKS TO HAVE THE RIGHT IDEA, DELAYING NE WINDS UNTIL 18-19Z. /GREGORIA && .PREV DISCUSSION... /ISSUED 654 PM EST WED NOV 27 2013/ UPDATE... EXPANDED THE SMALL CRAFT ADVISORY ACROSS THE GULF AND ATLANTIC WATERS TO INCLUDE LAKE OKEECHOBEE WITH LAKE SENSORS INDICATING WINDS IN EXCESS OF 20 KNOTS ACROSS PORTIONS OF THE LAKE. AFTER 06Z THURSDAY WINDS ARE FORECAST TO SLOWLY SUBSIDE...SO WILL LET THE ADVISORY FOR THE LAKE EXPIRE AT THAT TIME. FOR THE GULF WATERS...WINDS WILL REMAIN AROUND 20 KNOTS INTO THURSDAY WITH SEAS OF 8 TO 10 FEET POSSIBLE MAINLY ACROSS THE OFF SHORE WATERS INTO EARLY THURSDAY AND SLOWLY SUBSIDING INTO THURSDAY AFTERNOON. BASED ON THE CURRENT FORECAST THE SMALL CRAFT ADVISORY WAS EXTENDED TO 18Z THURSDAY. FOR THE ATLANTIC WATERS...WINDS TO NEAR 20 KNOTS WILL CONTINUE OVER NIGHT AND SLOWLY SUBSIDE LATER ON THURSDAY. AS WINDS BECOME MORE NORTHERLY EARLY THURSDAY GULF STREAM SEAS WILL SLOWLY INCREASE WITH SEAS TO NEAR 7 FEET POSSIBLE BY EARLY THURSDAY. THE SMALL CRAFT ADVISORY FOR THE ATLANTIC WATERS WAS ALSO EXTENDED TO 18Z THURSDAY. 60 PREV DISCUSSION... /ISSUED 637 PM EST WED NOV 27 2013/ AVIATION... SKIES SHOULD REMAIN MOSTLY CLEAR FOR THE EAST COAST TAF SITES OVERNIGHT. STRATUS AROUND 5KFT WAS MOVING ACROSS THE GULF WATERS...AND SOME OF THIS WILL MOVE ACROSS KAPF OVERNIGHT. WINDS WILL SHIFT TO THE NORTH AND NORTHEAST AROUND 10 KNOTS WITH HIGHER GUSTS THANKSGIVING DAY. SCT/BKN STRATUS AROUND 4KFT WILL MOVE INTO THE EAST COAST AREAS IN THE AFTERNOON. PREV DISCUSSION... /ISSUED 222 PM EST WED NOV 27 2013/ DRY AND COOLER CONDITIONS FOR SOUTH FLORIDA ON THANKSGIVING.... SHORT TERM... A COLD FRONT OVER THE EASTERN PORTION OF SOUTH FLORIDA WILL CONTINUE TO PUSH EAST THIS AFTERNOON AND SHOULD BE OVER THE BAHAMAS BY THIS EVENING. THE FRONT WILL CONTINUE TO MOVE EAST FURTHER INTO THE ATLANTIC WATERS TONIGHT INTO THANKSGIVING DAY AS HIGH PRESSURE OVER THE CENTRAL UNITED STATES MOVES SOUTHEAST INTO THE SOUTHEASTERN UNITED STATES. THIS WILL ALLOW FOR DRIER AND COOLER AIR TO WORK INTO THE AREA FROM THE NORTH TONIGHT INTO THANKSGIVING DAY...WHICH IN TURN WILL ALLOW FOR THE LOWS TONIGHT TO FALL DOWN INTO THE 40S OVER THE OVER MOST OF SOUTH FLORIDA EXCEPT AROUND 40 WEST OF LAKE OKEECHOBEE AND AROUND 50 OVER THE SOUTHEASTERN METRO AREAS OF SOUTH FLORIDA. THE WINDS WILL ALSO BE AROUND 5 TO 10 MPH OVER THE METRO AREAS TO AROUND 5 MPH OVER THE INTERIOR AREAS. THIS WILL ALLOW FOR THE WIND CHILLS TO FALL DOWN INTO THE LOWER TO MID 40S OVER MOST OF SOUTH FLORIDA LATE TONIGHT...EXCEPT UPPER 40S TO NEAR 50 OVER METRO BROWARD AND METRO MIAMI-DADE COUNTIES. THE HIGH WILL MOVE SLOWLY EAST INTO THE MID ATLANTIC WATERS THIS WEEKEND ALLOWING FOR THE WIND FLOW TO SWING TO A NORTHEAST DIRECTION. THIS WILL ALLOW FOR SOME SLOW WARMING IN THE TEMPERATURES THIS WEEKEND OVER SOUTH FLORIDA. HIGHS ON THURSDAY WILL BE IN THE 70S BEFORE INCREASING TO THE LOWER TO MID 80S BY THIS WEEKEND. LOWS ON THANKSGIVING NIGHT WILL BE IN THE 50S TO NEAR 60 BEFORE INCREASING TO THE 60S TO NEAR 70 THIS WEEKEND. THE WEATHER WILL ALSO BE MOSTLY DRY ACROSS SOUTH FLORIDA THIS WEEKEND DUE TO THE HIGH NORTH OF THE AREA MOVING SLOWLY EAST. THE ONLY EXCEPTION TO THIS IS OVER THE EAST COAST METRO AREAS WHERE A FEW SHOWERS COULD OCCUR ON THE NORTHEAST WIND FLOW. SO WILL KEEP A 10 PERCENT POPS IN PLACE FOR THE EAST COAST METRO AREAS FOR THIS WEEKEND. LONG TERM... THE HIGH WILL CONTINUE TO MOVE EAST INTO THE ATLANTIC WATERS EARLY NEXT WEEK ALLOWING FOR ANOTHER COLD FRONT CURRENTLY OVER THE NORTHWEST PORTION OF THE UNITED STATES TO MOVE SOUTHEAST AND THROUGH SOUTH FLORIDA. THIS FRONT WILL BRING A SLIGHT CHANCE OF SHOWERS TO THE EARLY NEXT WEEK...BEFORE DRY WEATHER WORKS BACK INTO THE AREA FROM THE NORTH. AVIATION... VFR CONDITIONS WILL PREVAIL FOR NEXT 24 HOURS AS HIGH PRESSURE BUILDS SOUTH INTO THE REGION. NORTHWEST WINDS OF 15-25 KTS TODAY WILL DIMINISH TO 10 KTS OVERNIGHT...BUT INCREASE AGAIN THURSDAY TO 15-20 KTS. WINDS SHOULD ALSO VEER TO NORTH-NORTHEAST BY MID-MORNING THURSDAY. MARINE... THE WINDS WILL BE NORTHERLY DIRECTION TONIGHT BEFORE SWINGING TO A NORTHEAST DIRECTION ON THANKSGIVING DAY...AND REMAIN AT A NORTHEAST DIRECTION THIS WEEKEND. THE WIND SPEEDS WILL ALSO REMAIN AT LEAST 20 KNOTS OVER THE MOST OF THE LOCAL WATERS...EXCEPT 15 TO 20 KNOTS OVER BISCAYNE BAY AND LAKE OKEECHOBEE TONIGHT THROUGH FRIDAY NIGHT. THIS WILL KEEP THE SEAS IN THE ATLANTIC WATERS AT 5 TO 7 FEET TONIGHT INTO FRIDAY NIGHT. FOR THE GULF SIDE...THE SEAS WILL BE 5 TO 7 FEET UP TO 10 FEET IN THE OFFSHORE WATERS TONIGHT BEFORE SLOWLY DECREASING TO LESS THAN 7 FEET BY THANKSGIVING NIGHT. SO WILL CONTINUE THE SCA FOR BOTH THE ATLANTIC AND GULF WATERS OF SOUTH FLORIDA FOR TONIGHT WITH A SCEC FOR BISCAYNE BAY AND LAKE OKEECHOBEE WATERS. FIRE WEATHER... THE RELATIVE HUMIDITY VALUES ON THANKSGIVING DAY SHOULD REMAIN ABOVE THE 35 PERCENT CRITICAL VALUE OVER SOUTH FLORIDA. HOWEVER...SOME ISOLATED AREAS OVER THE INTERIOR AND METRO AREAS OF COLLIER COUNTY COULD FALL DOWN CLOSE TO THE 35 PERCENT CRITICAL VALUE DURING THE AFTERNOON HOURS. AT THIS TIME...THE ENERGY RELEASE COMPONENT WILL REMAIN IN THE LOWER 20S FOR THANKSGIVING DAY AND THE 20 FOOT WINDS WILL REMAIN BELOW 15 MPH. SO WILL NOT BE ISSUING ANY FIRE WEATHER WATCH OR RED FLAG WARNINGS FOR COLLIER COUNTY OR REST OF SOUTH FLORIDA FOR THANKSGIVING DAY. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 64 77 69 80 / - 10 10 10 FORT LAUDERDALE 66 78 71 80 / - 10 10 10 MIAMI 67 79 71 81 / - 10 10 10 NAPLES 56 79 61 81 / - - - - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...RIP CURRENT RISK UNTIL 7 AM EST THIS MORNING FOR COASTAL COLLIER. AM...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM- WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE TERRITORIAL WATERS OF THE BAHAMAS. SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM- WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM. SMALL CRAFT ADVISORY UNTIL 1 AM EST EARLY THIS MORNING FOR LAKE OKEECHOBEE. GM...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM- COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM 20 TO 60 NM. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
230 PM CST THU NOV 28 2013 .DISCUSSION... 306 AM CST THE PRIMARY FORECAST CONCERNS ARE CENTERED ON CLOUD COVER AND TEMPERATURES THROUGH THE WEEKEND AND THEN CHANCES FOR PRECIPITATION NEXT WEEK IN WHAT APPEARS TO POSSIBLY BE AN UNSETTLED PATTERN...ALTHOUGH A HIGH DEGREE OF UNCERTAINTY. ONE MORE SHORT WAVE IS DIVING SOUTHEAST ACROSS THE GREAT LAKES THIS THANKSGIVING MORNING IN WHAT HAS BEEN A LITERAL PARADE OF THESE COLD-AIR-REINFORCING SYSTEMS. A 1017MB SURFACE LOW REFLECTION ACROSS IA WILL TRANSLATE EAST THIS MORNING AND WEAKEN AS IT DOES SUCH. MORNING CLOUDS IN PLACE WERE DEVELOPED WITHIN THE WARM AIR ADVECTION ENVELOPE OF THIS SYSTEM AND AS SUCH HAVE BASES MAINLY ABOVE 5000 FT...SO BELIEVE THEY WILL VACATE BY AFTERNOON ACROSS THE WESTERN AND SOUTHERN FORECAST AREA GIVEN THE CLOUD-BEARING WIND FLOW. LOW-LEVEL LAPSE RATES ARE MODESTLY STEEP BEHIND THE SYSTEM WITH SOME MARGINAL SATURATION FORECAST AT THE TOP OF THE MIXED LAYER...SO LIKELY SOME SCATTERED STRATOCU WILL CONTINUE. ALL-IN-ALL...EXPECTING SOME SUN LATE THIS MORNING AND AFTERNOON. GIVEN THE 850MB AND 925MB FORECAST TEMPS BY THE RAP AND NAM THIS AFTERNOON...WE ONCE AGAIN ARE IN THE BOTTOM TENTH PERCENTILE FOR THIS TIME OF YEAR. THIS FAVORS HIGHS IN THE LOWER TO MID 30S. SEE THE CLIMATE DISCUSSION BELOW FOR MORE ON WHERE THIS STACKS UP FOR THANKSGIVING DAYS. AS A CANADIAN SURFACE HIGH MOVES OVERHEAD TONIGHT TEMPERATURES SHOULD RADIATE QUICKLY THIS EVE...EVEN IF IT DOES TAKE A FEW HOURS AFTER SUNSET TO DIMINISH THE LINGERING STRATOCU. HAVE MID AND EVEN PATCHY LOWER TEENS IN OUTLYING AREAS. AS THE WIND FIELD OVER LAKE MI SHIFTS MORE NE TONIGHT IMMEDIATELY AHEAD OF THE HIGH CENTER...A LAKE PLUME OF AT LEAST CLOUDS LOOKS LIKELY INTO NORTHWEST INDIANA AND POSSIBLY NORTHEAST ILLINOIS. LAKE-INDUCED EQUILIBRIUM LEVELS AROUND 4500 FT FORECAST BY THE NAM SEEM A LITTLE SHALLOW FOR PRECIP AND ANY PRONOUNCED CONVERGENCE IS UNLIKELY. HAVE THUS ONLY ADDED A LOW CHANCE FOR SOME LIGHT SNOW IN NORTHWEST IN/FAR SOUTHEAST COOK COUNTY LATE TONIGHT AS WELL AS BUMPED UP CLOUD COVER. A MORE ZONAL PATTERN WILL MOVE OVER BY LATER FRIDAY INTO SATURDAY BRINGING MODERATING TEMPERATURES. THERE IS A FAIR AMOUNT OF SPREAD IN THE ENVELOPE OF GUIDANCE SOLUTIONS FOR HOW WARM SATURDAY WILL BE...AND POTENTIAL CLOUD COVER LIKELY HAS QUITE A BIT TO DO WITH THAT. THIS TIME OF YEAR SOUTHERLY LOW-LEVEL FLOW AFTER A COLD AIR MASS CAN READILY BECOME "CONTAMINATED" WITH SATURATION/CLOUDS. CLIMATOLOGY OF THE 850MB AND 925MB TEMPERATURES WOULD FAVOR MID AND MAYBE EVEN UPPER 40S...BUT THAT WARM CURRENTLY SEEMS UNLIKELY WITH AT LEAST SOME POTENTIAL FOR CLOUDS AND NOT THE STRONGEST OF WARM AIR ADVECTION SIGNALS. THE HEART OF THE SYSTEM IS OVER THE NORTHERN GREAT LAKES...SO FORCING AND SATURATION REMAINS MINIMAL OVER THE AREA. SO HAVE NO POPS AT THIS TIME. NEXT WEEK THE UNCERTAINTY REALLY STARTS TO RAMP UP BY MIDWEEK AFTER WHAT IS BECOMING A MORE FAVORED DRY SUNDAY AND MONDAY. ALTHOUGH MUCH LIKE SATURDAY...TEMPERATURE CONFIDENCE IS FAIRLY LOW GIVEN CLOUD POTENTIAL. IF CLOUDS ARE REMAINING INTO SUNDAY MORNING THEY VERY WELL COULD STICK AROUND ALL THE WAY THROUGH MONDAY NIGHT AS SURFACE PRESSURES ARE FORECAST TO BASICALLY REMAIN THE SAME...I.E. LITTLE ADVECTION. THE LONG ADVERTISED UPPER TROUGH ACROSS THE WEST COAST LOOKS TO EVOLVE IN THE BEGINNING OF THE WEEK AND FORCE DOWNSTREAM RIDGING AND SOUTHWEST FLOW ALOFT. THIS TROUGH SHOULD PACK QUITE A PUNCH OF COLD AIR INTO THE NORTHERN ROCKIES AND PLAINS...BUT THE MAIN BAROCLINIC ZONE DURING MIDWEEK LOOKS TO REMAIN TO THE NORTHWEST AND IF THAT IS THE CASE THEN ANY HEAVY WINTER PRECIP SHOULD AS WELL DURING MIDWEEK...BUT AGAIN CONFIDENCE IS LOW. ENERGY THAT TRANSLATES EAST FROM THIS TROUGH APPEARS TO BE IN PARTS AND THUS MULTIPLE CHANCES FOR PRECIP LOOK TO BE THE CASE ACROSS THE GREAT LAKES AND CORN BELT REGIONS DURING THE DEC 3-8 PERIOD. NIGHTTIME TEMPERATURES SHOULD BE MORE NEAR NORMAL OR EVEN ABOVE NORMAL GIVEN CLOUD COVER DURING MIDWEEK...BUT DAYTIME HIGHS COULD BE ANYWHERE IN A LARGE SPECTRUM OF SOLUTIONS DEPENDING ON STRENGTH OF SOUTHERLY FLOW AND WHEN LOW PASSAGES OCCUR. THOSE ARE BOTH VARIABLES DIFFICULT TO LOCK DOWN IN A FORECAST PATTERN OF A BROAD TROUGH IN THE WEST. MTF && .CLIMATE... 306 AM CST THE FORECAST HIGH TODAY FOR CHICAGO (O`HARE) IS 33 WHICH WOULD TIE MULTIPLE THANKSGIVINGS IN THE PAST TWO DECADES FOR A COOL HIGH...THE LAST BEING 2007. HOWEVER IF THE MERCURY STAYS BELOW THAT...IT WOULD BE THE COLDEST HIGH TEMPERATURE ON THANKSGIVING IN CHICAGO SINCE 1989. SIMILARLY FOR ROCKFORD...THE 31 DEGREE FORECAST HIGH WOULD BE THE COOLEST THANKSGIVING HIGH SINCE 1995 AND IF IT STAYS BELOW THAT IT WOULD BE THE COOLEST SINCE 1989. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * WEST NORTHWEST WIND BECOMING MORE NORTHWEST THIS AFTERNOON. * VFR CEILINGS EXPECTED THIS AFTERNOON...WITH A CHANCE FOR A BRIEF PERIOD OF MVFR CEILINGS EARLY THIS EVENING. RODRIGUEZ //DISCUSSION...UPDATED 18Z... AN APPROACHING COLD FRONT WILL PUSH ACROSS THE TERMINALS OVER THE NEXT 1-2 HOURS WITH WEST SOUTHWEST WINDS TURNING TO THE NORTHWEST...AND A RETURN OF VFR CEILINGS. THIS CLOUD COVER CAN BE OBSERVED MOVING SOUTHEAST ACROSS EASTERN IOWA AND SOUTHERN WISCONSIN...WITH DISTANCE SPEED TOOL BRINGING THIS TO RFD BY 19Z AND TO ORD BY 20Z. SHORT TERM GUIDANCE CONTINUES TO INDICATE THE POSSIBILITY OF MVFR CEILINGS LATER THIS EVENING...AND CANNOT RULE THIS OUT WITH COLDER AIR MOVING ACROSS THE REGION. SO HAVE SHOWED THIS POSSIBILITY IN THE TAF. VFR OR MVFR CEILINGS WILL NOT BE LONG LASTING THIS EVENING...WITH THIS AREA OF CLOUD COVER EXPECTED TO QUICKLY EXIT THE TERMINALS AND ONLY HIGH LEVEL CLOUDS TO THEN MOVE OVER THE TERMINALS THROUGH THE REMAINDER OF THE FORECAST PERIOD. WINDS WILL DIMINISH TONIGHT AND EVEN BECOME CALM OR LIGHT AND VARIABLE AS HIGH PRESSURE MOVES OVERHEAD...BUT THEN INCREASE OUT OF THE SOUTHEAST BY MID DAY FRIDAY. RODRIGUEZ //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE WITH WIND SPEED/DIRECTION. * LOW MEDIUM CONFIDENCE WITH MVFR POTENTIAL EARLY THIS EVENING. RODRIGUEZ //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...VFR. SATURDAY...VFR. SUNDAY AND MONDAY...MVFR POSSIBLE, TUESDAY...VFR. WEDNESDAY...CHANCE SHRA...MVFR POSSIBLE. MDB && .MARINE... 228 PM CST A BROAD RIDGE OF HIGH PRESSURE CONTINUES TO BE CENTERED ACROSS THE TENN VALLEY. WITH THE HIGH PRESSURE CENTERED SOUTH OF LAKE MICHIGAN...AND A WEAK LOW PRESSURE FLOATING SOUTHEAST ACROSS THE NORTHERN PORTIONS OF LAKE MICHIGAN THIS AFTERNOON...WINDS FOR THE SOUTHERN TWO-THIRDS OF LAKE MICHIGAN HAVE REMAINED WEST/NORTHWEST WHILE THE FAR NORTHERN SECTION IS EASTERLY. AT TIMES THE GRADIENT HAS BEEN TIGHT ENOUGH TO PRODUCE GUSTS TO 25KT NEAR THE STRAITS...HOWEVER IN GENERAL THE GRADIENT IS EXPECTED TO BE DIMINISHING. HIGH PRESSURE WILL BE LIFTING NORTHEAST ACROSS THE NORTHEASTERN CONUS...WHICH WILL ALLOW WINDS TO BACK TO THE SOUTHWEST/SOUTH FRIDAY AFTERNOON. THE GRADIENT DOES RAMP UP ALONG THE WESTERN EDGE OF THE HIGH PRESSURE FRIDAY NIGHT/SATURDAY. GUIDANCE HAS INDICATED THAT SOUTHERLY GUSTS MAY APPROACH 30KT...AND OCCASIONAL GALE FORCE GUSTS MAY OCCUR MAINLY FOR THE OPEN WATERS. A LOW PRESSURE WILL DEVELOP ACROSS THE NORTHERN PLAINS/SOUTHCENTRAL CANADA LATE FRI NIGHT...THEN STEADILY STRENGTHEN AS IT SLIDES EAST TOWARDS JAMES BAY SATURDAY AFTN. THIS MAY HELP TO PROLONG HIGHER GUSTS TO NEAR GALES FOR THE FAR NORTHERN PORTIONS OF LAKE MICHIGAN SAT. MEANWHILE FURTHER SOUTH THE GRADIENT WILL DIMINISH...WITH WINDS SHIFTING TO THE WEST THEN NORTH BEHIND A FRONTAL BOUNDARY SUN. THE GRADIENT DOES APPEAR TO REMAIN MINIMAL SUN NGT...WITH WEAK HIGH PRESSURE SLIDING NORTHEAST ACROSS NORTHEAST ONTARIO. THIS WILL ALLOW WINDS TO BECOME EASTERLY FOR EARLY NEXT WEEK...BUT WITH THE LACK OF ANY SIGNIFICANT GRADIENT...WINDS SHOULD REMAIN ARND 10-20KT FOR MON/TUE. THEN FOR THE MIDDLE OF NEXT WEEK FORECAST MODELS ARE INDICATING AN AREA OF LOW PRESSURE TO INTENSIFY ACROSS THE UPPER MIDWEST AND PIVOT EAST TOWARDS THE NORTHERN GREAT LAKES. THEN YET ANOTHER LOW PRESSURE TO WATCH LATER IN THE WEEK...WHICH COULD PROVIDE PROLONGED PERIOD OF SOUTH/SOUTHWEST WINDS AND BUILDING WAVES FOR THE NORTHERN PORTIONS OF LAKE MICHIGAN TUE NIGHT THROUGH THUR. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
147 PM CST THU NOV 28 2013 .DISCUSSION... 306 AM CST THE PRIMARY FORECAST CONCERNS ARE CENTERED ON CLOUD COVER AND TEMPERATURES THROUGH THE WEEKEND AND THEN CHANCES FOR PRECIPITATION NEXT WEEK IN WHAT APPEARS TO POSSIBLY BE AN UNSETTLED PATTERN...ALTHOUGH A HIGH DEGREE OF UNCERTAINTY. ONE MORE SHORT WAVE IS DIVING SOUTHEAST ACROSS THE GREAT LAKES THIS THANKSGIVING MORNING IN WHAT HAS BEEN A LITERAL PARADE OF THESE COLD-AIR-REINFORCING SYSTEMS. A 1017MB SURFACE LOW REFLECTION ACROSS IA WILL TRANSLATE EAST THIS MORNING AND WEAKEN AS IT DOES SUCH. MORNING CLOUDS IN PLACE WERE DEVELOPED WITHIN THE WARM AIR ADVECTION ENVELOPE OF THIS SYSTEM AND AS SUCH HAVE BASES MAINLY ABOVE 5000 FT...SO BELIEVE THEY WILL VACATE BY AFTERNOON ACROSS THE WESTERN AND SOUTHERN FORECAST AREA GIVEN THE CLOUD-BEARING WIND FLOW. LOW-LEVEL LAPSE RATES ARE MODESTLY STEEP BEHIND THE SYSTEM WITH SOME MARGINAL SATURATION FORECAST AT THE TOP OF THE MIXED LAYER...SO LIKELY SOME SCATTERED STRATOCU WILL CONTINUE. ALL-IN-ALL...EXPECTING SOME SUN LATE THIS MORNING AND AFTERNOON. GIVEN THE 850MB AND 925MB FORECAST TEMPS BY THE RAP AND NAM THIS AFTERNOON...WE ONCE AGAIN ARE IN THE BOTTOM TENTH PERCENTILE FOR THIS TIME OF YEAR. THIS FAVORS HIGHS IN THE LOWER TO MID 30S. SEE THE CLIMATE DISCUSSION BELOW FOR MORE ON WHERE THIS STACKS UP FOR THANKSGIVING DAYS. AS A CANADIAN SURFACE HIGH MOVES OVERHEAD TONIGHT TEMPERATURES SHOULD RADIATE QUICKLY THIS EVE...EVEN IF IT DOES TAKE A FEW HOURS AFTER SUNSET TO DIMINISH THE LINGERING STRATOCU. HAVE MID AND EVEN PATCHY LOWER TEENS IN OUTLYING AREAS. AS THE WIND FIELD OVER LAKE MI SHIFTS MORE NE TONIGHT IMMEDIATELY AHEAD OF THE HIGH CENTER...A LAKE PLUME OF AT LEAST CLOUDS LOOKS LIKELY INTO NORTHWEST INDIANA AND POSSIBLY NORTHEAST ILLINOIS. LAKE-INDUCED EQUILIBRIUM LEVELS AROUND 4500 FT FORECAST BY THE NAM SEEM A LITTLE SHALLOW FOR PRECIP AND ANY PRONOUNCED CONVERGENCE IS UNLIKELY. HAVE THUS ONLY ADDED A LOW CHANCE FOR SOME LIGHT SNOW IN NORTHWEST IN/FAR SOUTHEAST COOK COUNTY LATE TONIGHT AS WELL AS BUMPED UP CLOUD COVER. A MORE ZONAL PATTERN WILL MOVE OVER BY LATER FRIDAY INTO SATURDAY BRINGING MODERATING TEMPERATURES. THERE IS A FAIR AMOUNT OF SPREAD IN THE ENVELOPE OF GUIDANCE SOLUTIONS FOR HOW WARM SATURDAY WILL BE...AND POTENTIAL CLOUD COVER LIKELY HAS QUITE A BIT TO DO WITH THAT. THIS TIME OF YEAR SOUTHERLY LOW-LEVEL FLOW AFTER A COLD AIR MASS CAN READILY BECOME "CONTAMINATED" WITH SATURATION/CLOUDS. CLIMATOLOGY OF THE 850MB AND 925MB TEMPERATURES WOULD FAVOR MID AND MAYBE EVEN UPPER 40S...BUT THAT WARM CURRENTLY SEEMS UNLIKELY WITH AT LEAST SOME POTENTIAL FOR CLOUDS AND NOT THE STRONGEST OF WARM AIR ADVECTION SIGNALS. THE HEART OF THE SYSTEM IS OVER THE NORTHERN GREAT LAKES...SO FORCING AND SATURATION REMAINS MINIMAL OVER THE AREA. SO HAVE NO POPS AT THIS TIME. NEXT WEEK THE UNCERTAINTY REALLY STARTS TO RAMP UP BY MIDWEEK AFTER WHAT IS BECOMING A MORE FAVORED DRY SUNDAY AND MONDAY. ALTHOUGH MUCH LIKE SATURDAY...TEMPERATURE CONFIDENCE IS FAIRLY LOW GIVEN CLOUD POTENTIAL. IF CLOUDS ARE REMAINING INTO SUNDAY MORNING THEY VERY WELL COULD STICK AROUND ALL THE WAY THROUGH MONDAY NIGHT AS SURFACE PRESSURES ARE FORECAST TO BASICALLY REMAIN THE SAME...I.E. LITTLE ADVECTION. THE LONG ADVERTISED UPPER TROUGH ACROSS THE WEST COAST LOOKS TO EVOLVE IN THE BEGINNING OF THE WEEK AND FORCE DOWNSTREAM RIDGING AND SOUTHWEST FLOW ALOFT. THIS TROUGH SHOULD PACK QUITE A PUNCH OF COLD AIR INTO THE NORTHERN ROCKIES AND PLAINS...BUT THE MAIN BAROCLINIC ZONE DURING MIDWEEK LOOKS TO REMAIN TO THE NORTHWEST AND IF THAT IS THE CASE THEN ANY HEAVY WINTER PRECIP SHOULD AS WELL DURING MIDWEEK...BUT AGAIN CONFIDENCE IS LOW. ENERGY THAT TRANSLATES EAST FROM THIS TROUGH APPEARS TO BE IN PARTS AND THUS MULTIPLE CHANCES FOR PRECIP LOOK TO BE THE CASE ACROSS THE GREAT LAKES AND CORN BELT REGIONS DURING THE DEC 3-8 PERIOD. NIGHTTIME TEMPERATURES SHOULD BE MORE NEAR NORMAL OR EVEN ABOVE NORMAL GIVEN CLOUD COVER DURING MIDWEEK...BUT DAYTIME HIGHS COULD BE ANYWHERE IN A LARGE SPECTRUM OF SOLUTIONS DEPENDING ON STRENGTH OF SOUTHERLY FLOW AND WHEN LOW PASSAGES OCCUR. THOSE ARE BOTH VARIABLES DIFFICULT TO LOCK DOWN IN A FORECAST PATTERN OF A BROAD TROUGH IN THE WEST. MTF && .CLIMATE... 306 AM CST THE FORECAST HIGH TODAY FOR CHICAGO (O`HARE) IS 33 WHICH WOULD TIE MULTIPLE THANKSGIVINGS IN THE PAST TWO DECADES FOR A COOL HIGH...THE LAST BEING 2007. HOWEVER IF THE MERCURY STAYS BELOW THAT...IT WOULD BE THE COLDEST HIGH TEMPERATURE ON THANKSGIVING IN CHICAGO SINCE 1989. SIMILARLY FOR ROCKFORD...THE 31 DEGREE FORECAST HIGH WOULD BE THE COOLEST THANKSGIVING HIGH SINCE 1995 AND IF IT STAYS BELOW THAT IT WOULD BE THE COOLEST SINCE 1989. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * WEST NORTHWEST WIND BECOMING MORE NORTHWEST THIS AFTERNOON. * VFR CEILINGS EXPECTED THIS AFTERNOON...WITH A CHANCE FOR A BRIEF PERIOD OF MVFR CEILINGS EARLY THIS EVENING. RODRIGUEZ //DISCUSSION...UPDATED 18Z... AN APPROACHING COLD FRONT WILL PUSH ACROSS THE TERMINALS OVER THE NEXT 1-2 HOURS WITH WEST SOUTHWEST WINDS TURNING TO THE NORTHWEST...AND A RETURN OF VFR CEILINGS. THIS CLOUD COVER CAN BE OBSERVED MOVING SOUTHEAST ACROSS EASTERN IOWA AND SOUTHERN WISCONSIN...WITH DISTANCE SPEED TOOL BRINGING THIS TO RFD BY 19Z AND TO ORD BY 20Z. SHORT TERM GUIDANCE CONTINUES TO INDICATE THE POSSIBILITY OF MVFR CEILINGS LATER THIS EVENING...AND CANNOT RULE THIS OUT WITH COLDER AIR MOVING ACROSS THE REGION. SO HAVE SHOWED THIS POSSIBILITY IN THE TAF. VFR OR MVFR CEILINGS WILL NOT BE LONG LASTING THIS EVENING...WITH THIS AREA OF CLOUD COVER EXPECTED TO QUICKLY EXIT THE TERMINALS AND ONLY HIGH LEVEL CLOUDS TO THEN MOVE OVER THE TERMINALS THROUGH THE REMAINDER OF THE FORECAST PERIOD. WINDS WILL DIMINISH TONIGHT AND EVEN BECOME CALM OR LIGHT AND VARIABLE AS HIGH PRESSURE MOVES OVERHEAD...BUT THEN INCREASE OUT OF THE SOUTHEAST BY MID DAY FRIDAY. RODRIGUEZ //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE WITH WIND SPEED/DIRECTION. * LOW MEDIUM CONFIDENCE WITH MVFR POTENTIAL EARLY THIS EVENING. RODRIGUEZ //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...VFR. SATURDAY...VFR. SUNDAY AND MONDAY...MVFR POSSIBLE, TUESDAY...VFR. WEDNESDAY...CHANCE SHRA...MVFR POSSIBLE. MDB && .MARINE... 221 AM CST THE MAIN FOCUS OF THE FORECAST CONTINUES TO BE THE POTENTIAL FOR GALE FORCE WINDS LATE FRIDAY NIGHT THROUGH MIDDAY/EARLY AFTERNOON SATURDAY...MAINLY ACROSS THE NORTH HALF OF THE LAKE. CURRENTLY...SURFACE LOW PRESSURE CONTINUES TO DEEPEN AS IT MOVES NORTHWARD INTO EASTERN QUEBEC AND NEWFOUNDLAND. HIGH PRESSURE RIDGING IS CROSSING LAKE MICHIGAN EARLY THIS MORNING WITH A WEAK AREA OF LOW PRESSURE OVER WESTERN MINNESOTA AND NORTHWEST IOWA. THIS LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATER TODAY AND THIS EVENING. WINDS HAVE TURNED WEST AND SOUTHWEST THANKS TO THE PASSAGE OF THE RIDGE AXIS WITH SPEEDS DIMINISHING BUT THEY WILL INCREASE SOMEWHAT AS THE LOW CROSSES THE AREA LATER TODAY. A NARROW CORRIDOR OF OFFSHORE SOUTHEASTERLY WINDS IS OCCURRING ALONG THE MICHIGAN SHORE BUT WILL DIMINISH THROUGH MID MORNING. WINDS ACROSS FAR NORTHERN LAKE MICHIGAN WILL BE TRICKY AS THE LOW CENTER IS EXPECTED TO CROSS THIS AREA THIS AFTERNOON. THIS WILL LIKELY LEAD TO AN EASTERLY SURFACE FLOW OVER FAR NORTHERN LAKE MICHIGAN LATER THIS MORNING AND THIS AFTERNOON...WHILE THE REST OF THE LAKE SEES WEST TO SOUTHWEST WINDS. A COOL FRONTAL BOUNDARY WILL CROSS THE LAKE LATER TODAY TURNING WINDS TO THE NORTHWEST. HIGH PRESSURE WILL SPREAD IN BEHIND THE FRONT AND STRENGTHEN AS IT CROSSES THE LAKE FRIDAY BEFORE SHIFTING TO THE EAST. THIS WILL TURN WINDS BACK TO THE SOUTH BY FRIDAY AFTERNOON WITH RATHER LIGHT SPEEDS. THE HIGH WILL CONTINUE TO STRENGTHEN AS IT MOVES ACROSS THE NORTHEAST U.S. WHILE A CLIPPER DROPS SOUTHEAST ACROSS WESTERN ONTARIO JUST NORTH OF LAKE SUPERIOR SATURDAY. THE PRESSURE GRADIENT WILL TIGHTEN BETWEEN THESE TWO SYSTEMS LEADING TO STRONG SOUTH TO SOUTHWEST WINDS LATE FRIDAY NIGHT AND SATURDAY MORNING. THE STRONGEST SPEEDS WILL OCCUR ACROSS NORTHERN PORTIONS OF THE LAKE. WILL HOLD WINDS TO 30 KT FOR NOW WITH THE STRONGEST WINDS NORTH...BUT AM CONCERNED THAT AN INCREASE TO GALES MAY BE NEEDED. THIS SYSTEM IS NOT TOO UNLIKE SEVERAL WHICH WE SAW EARLIER THIS FALL THAT FEATURED SURFACE LOWS PASSING TO THE NORTH AND WINDS THAT WERE HIGHER THAN EXPECTED. THIS MAY NOT BE THE CASE WITH THIS PARTICULAR SYSTEM BUT IT IS WORTH NOTING GIVEN THAT UNSTABLE CONDITIONS WILL BE IN PLACE ACROSS THE LAKE SIMILAR TO THESE EARLIER SYSTEMS. A COLD FRONT CROSSES THE LAKE SATURDAY AFTERNOON ALLOWING WINDS TO DROP OFF SATURDAY EVENING. ANOTHER AREA OF HIGH PRESSURE WILL MOVE ACROSS THE REGION SUNDAY AND CONTINUE TO KEEP LIGHTER WINDS IN PLACE THROUGH TUESDAY. FORECAST CONFIDENCE DROPS OFF BY WEDNESDAY BUT IT DOES APPEAR THAT A MORE ACTIVE PATTERN WILL BE SETTING UP BRINGING INCREASING CHANCES FOR STRONGER WINDS. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1218 PM CST THU NOV 28 2013 .DISCUSSION... 306 AM CST THE PRIMARY FORECAST CONCERNS ARE CENTERED ON CLOUD COVER AND TEMPERATURES THROUGH THE WEEKEND AND THEN CHANCES FOR PRECIPITATION NEXT WEEK IN WHAT APPEARS TO POSSIBLY BE AN UNSETTLED PATTERN...ALTHOUGH A HIGH DEGREE OF UNCERTAINTY. ONE MORE SHORT WAVE IS DIVING SOUTHEAST ACROSS THE GREAT LAKES THIS THANKSGIVING MORNING IN WHAT HAS BEEN A LITERAL PARADE OF THESE COLD-AIR-REINFORCING SYSTEMS. A 1017MB SURFACE LOW REFLECTION ACROSS IA WILL TRANSLATE EAST THIS MORNING AND WEAKEN AS IT DOES SUCH. MORNING CLOUDS IN PLACE WERE DEVELOPED WITHIN THE WARM AIR ADVECTION ENVELOPE OF THIS SYSTEM AND AS SUCH HAVE BASES MAINLY ABOVE 5000 FT...SO BELIEVE THEY WILL VACATE BY AFTERNOON ACROSS THE WESTERN AND SOUTHERN FORECAST AREA GIVEN THE CLOUD-BEARING WIND FLOW. LOW-LEVEL LAPSE RATES ARE MODESTLY STEEP BEHIND THE SYSTEM WITH SOME MARGINAL SATURATION FORECAST AT THE TOP OF THE MIXED LAYER...SO LIKELY SOME SCATTERED STRATOCU WILL CONTINUE. ALL-IN-ALL...EXPECTING SOME SUN LATE THIS MORNING AND AFTERNOON. GIVEN THE 850MB AND 925MB FORECAST TEMPS BY THE RAP AND NAM THIS AFTERNOON...WE ONCE AGAIN ARE IN THE BOTTOM TENTH PERCENTILE FOR THIS TIME OF YEAR. THIS FAVORS HIGHS IN THE LOWER TO MID 30S. SEE THE CLIMATE DISCUSSION BELOW FOR MORE ON WHERE THIS STACKS UP FOR THANKSGIVING DAYS. AS A CANADIAN SURFACE HIGH MOVES OVERHEAD TONIGHT TEMPERATURES SHOULD RADIATE QUICKLY THIS EVE...EVEN IF IT DOES TAKE A FEW HOURS AFTER SUNSET TO DIMINISH THE LINGERING STRATOCU. HAVE MID AND EVEN PATCHY LOWER TEENS IN OUTLYING AREAS. AS THE WIND FIELD OVER LAKE MI SHIFTS MORE NE TONIGHT IMMEDIATELY AHEAD OF THE HIGH CENTER...A LAKE PLUME OF AT LEAST CLOUDS LOOKS LIKELY INTO NORTHWEST INDIANA AND POSSIBLY NORTHEAST ILLINOIS. LAKE-INDUCED EQUILIBRIUM LEVELS AROUND 4500 FT FORECAST BY THE NAM SEEM A LITTLE SHALLOW FOR PRECIP AND ANY PRONOUNCED CONVERGENCE IS UNLIKELY. HAVE THUS ONLY ADDED A LOW CHANCE FOR SOME LIGHT SNOW IN NORTHWEST IN/FAR SOUTHEAST COOK COUNTY LATE TONIGHT AS WELL AS BUMPED UP CLOUD COVER. A MORE ZONAL PATTERN WILL MOVE OVER BY LATER FRIDAY INTO SATURDAY BRINGING MODERATING TEMPERATURES. THERE IS A FAIR AMOUNT OF SPREAD IN THE ENVELOPE OF GUIDANCE SOLUTIONS FOR HOW WARM SATURDAY WILL BE...AND POTENTIAL CLOUD COVER LIKELY HAS QUITE A BIT TO DO WITH THAT. THIS TIME OF YEAR SOUTHERLY LOW-LEVEL FLOW AFTER A COLD AIR MASS CAN READILY BECOME "CONTAMINATED" WITH SATURATION/CLOUDS. CLIMATOLOGY OF THE 850MB AND 925MB TEMPERATURES WOULD FAVOR MID AND MAYBE EVEN UPPER 40S...BUT THAT WARM CURRENTLY SEEMS UNLIKELY WITH AT LEAST SOME POTENTIAL FOR CLOUDS AND NOT THE STRONGEST OF WARM AIR ADVECTION SIGNALS. THE HEART OF THE SYSTEM IS OVER THE NORTHERN GREAT LAKES...SO FORCING AND SATURATION REMAINS MINIMAL OVER THE AREA. SO HAVE NO POPS AT THIS TIME. NEXT WEEK THE UNCERTAINTY REALLY STARTS TO RAMP UP BY MIDWEEK AFTER WHAT IS BECOMING A MORE FAVORED DRY SUNDAY AND MONDAY. ALTHOUGH MUCH LIKE SATURDAY...TEMPERATURE CONFIDENCE IS FAIRLY LOW GIVEN CLOUD POTENTIAL. IF CLOUDS ARE REMAINING INTO SUNDAY MORNING THEY VERY WELL COULD STICK AROUND ALL THE WAY THROUGH MONDAY NIGHT AS SURFACE PRESSURES ARE FORECAST TO BASICALLY REMAIN THE SAME...I.E. LITTLE ADVECTION. THE LONG ADVERTISED UPPER TROUGH ACROSS THE WEST COAST LOOKS TO EVOLVE IN THE BEGINNING OF THE WEEK AND FORCE DOWNSTREAM RIDGING AND SOUTHWEST FLOW ALOFT. THIS TROUGH SHOULD PACK QUITE A PUNCH OF COLD AIR INTO THE NORTHERN ROCKIES AND PLAINS...BUT THE MAIN BAROCLINIC ZONE DURING MIDWEEK LOOKS TO REMAIN TO THE NORTHWEST AND IF THAT IS THE CASE THEN ANY HEAVY WINTER PRECIP SHOULD AS WELL DURING MIDWEEK...BUT AGAIN CONFIDENCE IS LOW. ENERGY THAT TRANSLATES EAST FROM THIS TROUGH APPEARS TO BE IN PARTS AND THUS MULTIPLE CHANCES FOR PRECIP LOOK TO BE THE CASE ACROSS THE GREAT LAKES AND CORN BELT REGIONS DURING THE DEC 3-8 PERIOD. NIGHTTIME TEMPERATURES SHOULD BE MORE NEAR NORMAL OR EVEN ABOVE NORMAL GIVEN CLOUD COVER DURING MIDWEEK...BUT DAYTIME HIGHS COULD BE ANYWHERE IN A LARGE SPECTRUM OF SOLUTIONS DEPENDING ON STRENGTH OF SOUTHERLY FLOW AND WHEN LOW PASSAGES OCCUR. THOSE ARE BOTH VARIABLES DIFFICULT TO LOCK DOWN IN A FORECAST PATTERN OF A BROAD TROUGH IN THE WEST. MTF && .CLIMATE... 306 AM CST THE FORECAST HIGH TODAY FOR CHICAGO (O`HARE) IS 33 WHICH WOULD TIE MULTIPLE THANKSGIVINGS IN THE PAST TWO DECADES FOR A COOL HIGH...THE LAST BEING 2007. HOWEVER IF THE MERCURY STAYS BELOW THAT...IT WOULD BE THE COLDEST HIGH TEMPERATURE ON THANKSGIVING IN CHICAGO SINCE 1989. SIMILARLY FOR ROCKFORD...THE 31 DEGREE FORECAST HIGH WOULD BE THE COOLEST THANKSGIVING HIGH SINCE 1995 AND IF IT STAYS BELOW THAT IT WOULD BE THE COOLEST SINCE 1989. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * WIND SHIFT FROM WEST SOUTHWEST TO NORTHWEST BY 20Z. * VFR CEILINGS EXPECTED THIS AFTERNOON...WITH A CHANCE FOR A BRIEF PERIOD OF MVFR CEILINGS EARLY THIS EVENING. RODRIGUEZ //DISCUSSION...UPDATED 18Z... AN APPROACHING COLD FRONT WILL PUSH ACROSS THE TERMINALS OVER THE NEXT 1-2 HOURS WITH WEST SOUTHWEST WINDS TURNING TO THE NORTHWEST...AND A RETURN OF VFR CEILINGS. THIS CLOUD COVER CAN BE OBSERVED MOVING SOUTHEAST ACROSS EASTERN IOWA AND SOUTHERN WISCONSIN...WITH DISTANCE SPEED TOOL BRINGING THIS TO RFD BY 19Z AND TO ORD BY 20Z. SHORT TERM GUIDANCE CONTINUES TO INDICATE THE POSSIBILITY OF MVFR CEILINGS LATER THIS EVENING...AND CANNOT RULE THIS OUT WITH COLDER AIR MOVING ACROSS THE REGION. SO HAVE SHOWED THIS POSSIBILITY IN THE TAF. VFR OR MVFR CEILINGS WILL NOT BE LONG LASTING THIS EVENING...WITH THIS AREA OF CLOUD COVER EXPECTED TO QUICKLY EXIT THE TERMINALS AND ONLY HIGH LEVEL CLOUDS TO THEN MOVE OVER THE TERMINALS THROUGH THE REMAINDER OF THE FORECAST PERIOD. WINDS WILL DIMINISH TONIGHT AND EVEN BECOME CALM OR LIGHT AND VARIABLE AS HIGH PRESSURE MOVES OVERHEAD...BUT THEN INCREASE OUT OF THE SOUTHEAST BY MID DAY FRIDAY. RODRIGUEZ //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH CONFIDENCE WITH WIND SPEED/DIRECTION. * LOW MEDIUM CONFIDENCE WITH MVFR POTENTIAL EARLY THIS EVENING. RODRIGUEZ //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...VFR. SATURDAY...VFR. SUNDAY AND MONDAY...MVFR POSSIBLE, TUESDAY...VFR. WEDNESDAY...CHANCE SHRA...MVFR POSSIBLE. MDB && .MARINE... 221 AM CST THE MAIN FOCUS OF THE FORECAST CONTINUES TO BE THE POTENTIAL FOR GALE FORCE WINDS LATE FRIDAY NIGHT THROUGH MIDDAY/EARLY AFTERNOON SATURDAY...MAINLY ACROSS THE NORTH HALF OF THE LAKE. CURRENTLY...SURFACE LOW PRESSURE CONTINUES TO DEEPEN AS IT MOVES NORTHWARD INTO EASTERN QUEBEC AND NEWFOUNDLAND. HIGH PRESSURE RIDGING IS CROSSING LAKE MICHIGAN EARLY THIS MORNING WITH A WEAK AREA OF LOW PRESSURE OVER WESTERN MINNESOTA AND NORTHWEST IOWA. THIS LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATER TODAY AND THIS EVENING. WINDS HAVE TURNED WEST AND SOUTHWEST THANKS TO THE PASSAGE OF THE RIDGE AXIS WITH SPEEDS DIMINISHING BUT THEY WILL INCREASE SOMEWHAT AS THE LOW CROSSES THE AREA LATER TODAY. A NARROW CORRIDOR OF OFFSHORE SOUTHEASTERLY WINDS IS OCCURRING ALONG THE MICHIGAN SHORE BUT WILL DIMINISH THROUGH MID MORNING. WINDS ACROSS FAR NORTHERN LAKE MICHIGAN WILL BE TRICKY AS THE LOW CENTER IS EXPECTED TO CROSS THIS AREA THIS AFTERNOON. THIS WILL LIKELY LEAD TO AN EASTERLY SURFACE FLOW OVER FAR NORTHERN LAKE MICHIGAN LATER THIS MORNING AND THIS AFTERNOON...WHILE THE REST OF THE LAKE SEES WEST TO SOUTHWEST WINDS. A COOL FRONTAL BOUNDARY WILL CROSS THE LAKE LATER TODAY TURNING WINDS TO THE NORTHWEST. HIGH PRESSURE WILL SPREAD IN BEHIND THE FRONT AND STRENGTHEN AS IT CROSSES THE LAKE FRIDAY BEFORE SHIFTING TO THE EAST. THIS WILL TURN WINDS BACK TO THE SOUTH BY FRIDAY AFTERNOON WITH RATHER LIGHT SPEEDS. THE HIGH WILL CONTINUE TO STRENGTHEN AS IT MOVES ACROSS THE NORTHEAST U.S. WHILE A CLIPPER DROPS SOUTHEAST ACROSS WESTERN ONTARIO JUST NORTH OF LAKE SUPERIOR SATURDAY. THE PRESSURE GRADIENT WILL TIGHTEN BETWEEN THESE TWO SYSTEMS LEADING TO STRONG SOUTH TO SOUTHWEST WINDS LATE FRIDAY NIGHT AND SATURDAY MORNING. THE STRONGEST SPEEDS WILL OCCUR ACROSS NORTHERN PORTIONS OF THE LAKE. WILL HOLD WINDS TO 30 KT FOR NOW WITH THE STRONGEST WINDS NORTH...BUT AM CONCERNED THAT AN INCREASE TO GALES MAY BE NEEDED. THIS SYSTEM IS NOT TOO UNLIKE SEVERAL WHICH WE SAW EARLIER THIS FALL THAT FEATURED SURFACE LOWS PASSING TO THE NORTH AND WINDS THAT WERE HIGHER THAN EXPECTED. THIS MAY NOT BE THE CASE WITH THIS PARTICULAR SYSTEM BUT IT IS WORTH NOTING GIVEN THAT UNSTABLE CONDITIONS WILL BE IN PLACE ACROSS THE LAKE SIMILAR TO THESE EARLIER SYSTEMS. A COLD FRONT CROSSES THE LAKE SATURDAY AFTERNOON ALLOWING WINDS TO DROP OFF SATURDAY EVENING. ANOTHER AREA OF HIGH PRESSURE WILL MOVE ACROSS THE REGION SUNDAY AND CONTINUE TO KEEP LIGHTER WINDS IN PLACE THROUGH TUESDAY. FORECAST CONFIDENCE DROPS OFF BY WEDNESDAY BUT IT DOES APPEAR THAT A MORE ACTIVE PATTERN WILL BE SETTING UP BRINGING INCREASING CHANCES FOR STRONGER WINDS. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1005 AM CST THU NOV 28 2013 .DISCUSSION... 306 AM CST THE PRIMARY FORECAST CONCERNS ARE CENTERED ON CLOUD COVER AND TEMPERATURES THROUGH THE WEEKEND AND THEN CHANCES FOR PRECIPITATION NEXT WEEK IN WHAT APPEARS TO POSSIBLY BE AN UNSETTLED PATTERN...ALTHOUGH A HIGH DEGREE OF UNCERTAINTY. ONE MORE SHORT WAVE IS DIVING SOUTHEAST ACROSS THE GREAT LAKES THIS THANKSGIVING MORNING IN WHAT HAS BEEN A LITERAL PARADE OF THESE COLD-AIR-REINFORCING SYSTEMS. A 1017MB SURFACE LOW REFLECTION ACROSS IA WILL TRANSLATE EAST THIS MORNING AND WEAKEN AS IT DOES SUCH. MORNING CLOUDS IN PLACE WERE DEVELOPED WITHIN THE WARM AIR ADVECTION ENVELOPE OF THIS SYSTEM AND AS SUCH HAVE BASES MAINLY ABOVE 5000 FT...SO BELIEVE THEY WILL VACATE BY AFTERNOON ACROSS THE WESTERN AND SOUTHERN FORECAST AREA GIVEN THE CLOUD-BEARING WIND FLOW. LOW-LEVEL LAPSE RATES ARE MODESTLY STEEP BEHIND THE SYSTEM WITH SOME MARGINAL SATURATION FORECAST AT THE TOP OF THE MIXED LAYER...SO LIKELY SOME SCATTERED STRATOCU WILL CONTINUE. ALL-IN-ALL...EXPECTING SOME SUN LATE THIS MORNING AND AFTERNOON. GIVEN THE 850MB AND 925MB FORECAST TEMPS BY THE RAP AND NAM THIS AFTERNOON...WE ONCE AGAIN ARE IN THE BOTTOM TENTH PERCENTILE FOR THIS TIME OF YEAR. THIS FAVORS HIGHS IN THE LOWER TO MID 30S. SEE THE CLIMATE DISCUSSION BELOW FOR MORE ON WHERE THIS STACKS UP FOR THANKSGIVING DAYS. AS A CANADIAN SURFACE HIGH MOVES OVERHEAD TONIGHT TEMPERATURES SHOULD RADIATE QUICKLY THIS EVE...EVEN IF IT DOES TAKE A FEW HOURS AFTER SUNSET TO DIMINISH THE LINGERING STRATOCU. HAVE MID AND EVEN PATCHY LOWER TEENS IN OUTLYING AREAS. AS THE WIND FIELD OVER LAKE MI SHIFTS MORE NE TONIGHT IMMEDIATELY AHEAD OF THE HIGH CENTER...A LAKE PLUME OF AT LEAST CLOUDS LOOKS LIKELY INTO NORTHWEST INDIANA AND POSSIBLY NORTHEAST ILLINOIS. LAKE-INDUCED EQUILIBRIUM LEVELS AROUND 4500 FT FORECAST BY THE NAM SEEM A LITTLE SHALLOW FOR PRECIP AND ANY PRONOUNCED CONVERGENCE IS UNLIKELY. HAVE THUS ONLY ADDED A LOW CHANCE FOR SOME LIGHT SNOW IN NORTHWEST IN/FAR SOUTHEAST COOK COUNTY LATE TONIGHT AS WELL AS BUMPED UP CLOUD COVER. A MORE ZONAL PATTERN WILL MOVE OVER BY LATER FRIDAY INTO SATURDAY BRINGING MODERATING TEMPERATURES. THERE IS A FAIR AMOUNT OF SPREAD IN THE ENVELOPE OF GUIDANCE SOLUTIONS FOR HOW WARM SATURDAY WILL BE...AND POTENTIAL CLOUD COVER LIKELY HAS QUITE A BIT TO DO WITH THAT. THIS TIME OF YEAR SOUTHERLY LOW-LEVEL FLOW AFTER A COLD AIR MASS CAN READILY BECOME "CONTAMINATED" WITH SATURATION/CLOUDS. CLIMATOLOGY OF THE 850MB AND 925MB TEMPERATURES WOULD FAVOR MID AND MAYBE EVEN UPPER 40S...BUT THAT WARM CURRENTLY SEEMS UNLIKELY WITH AT LEAST SOME POTENTIAL FOR CLOUDS AND NOT THE STRONGEST OF WARM AIR ADVECTION SIGNALS. THE HEART OF THE SYSTEM IS OVER THE NORTHERN GREAT LAKES...SO FORCING AND SATURATION REMAINS MINIMAL OVER THE AREA. SO HAVE NO POPS AT THIS TIME. NEXT WEEK THE UNCERTAINTY REALLY STARTS TO RAMP UP BY MIDWEEK AFTER WHAT IS BECOMING A MORE FAVORED DRY SUNDAY AND MONDAY. ALTHOUGH MUCH LIKE SATURDAY...TEMPERATURE CONFIDENCE IS FAIRLY LOW GIVEN CLOUD POTENTIAL. IF CLOUDS ARE REMAINING INTO SUNDAY MORNING THEY VERY WELL COULD STICK AROUND ALL THE WAY THROUGH MONDAY NIGHT AS SURFACE PRESSURES ARE FORECAST TO BASICALLY REMAIN THE SAME...I.E. LITTLE ADVECTION. THE LONG ADVERTISED UPPER TROUGH ACROSS THE WEST COAST LOOKS TO EVOLVE IN THE BEGINNING OF THE WEEK AND FORCE DOWNSTREAM RIDGING AND SOUTHWEST FLOW ALOFT. THIS TROUGH SHOULD PACK QUITE A PUNCH OF COLD AIR INTO THE NORTHERN ROCKIES AND PLAINS...BUT THE MAIN BAROCLINIC ZONE DURING MIDWEEK LOOKS TO REMAIN TO THE NORTHWEST AND IF THAT IS THE CASE THEN ANY HEAVY WINTER PRECIP SHOULD AS WELL DURING MIDWEEK...BUT AGAIN CONFIDENCE IS LOW. ENERGY THAT TRANSLATES EAST FROM THIS TROUGH APPEARS TO BE IN PARTS AND THUS MULTIPLE CHANCES FOR PRECIP LOOK TO BE THE CASE ACROSS THE GREAT LAKES AND CORN BELT REGIONS DURING THE DEC 3-8 PERIOD. NIGHTTIME TEMPERATURES SHOULD BE MORE NEAR NORMAL OR EVEN ABOVE NORMAL GIVEN CLOUD COVER DURING MIDWEEK...BUT DAYTIME HIGHS COULD BE ANYWHERE IN A LARGE SPECTRUM OF SOLUTIONS DEPENDING ON STRENGTH OF SOUTHERLY FLOW AND WHEN LOW PASSAGES OCCUR. THOSE ARE BOTH VARIABLES DIFFICULT TO LOCK DOWN IN A FORECAST PATTERN OF A BROAD TROUGH IN THE WEST. MTF && .CLIMATE... 306 AM CST THE FORECAST HIGH TODAY FOR CHICAGO (O`HARE) IS 33 WHICH WOULD TIE MULTIPLE THANKSGIVINGS IN THE PAST TWO DECADES FOR A COOL HIGH...THE LAST BEING 2007. HOWEVER IF THE MERCURY STAYS BELOW THAT...IT WOULD BE THE COLDEST HIGH TEMPERATURE ON THANKSGIVING IN CHICAGO SINCE 1989. SIMILARLY FOR ROCKFORD...THE 31 DEGREE FORECAST HIGH WOULD BE THE COOLEST THANKSGIVING HIGH SINCE 1995 AND IF IT STAYS BELOW THAT IT WOULD BE THE COOLEST SINCE 1989. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * WIND SHIFT FROM SOUTHWEST TO NORTHWEST TOWARD 20Z. * VFR EXPECTED TO CONTINUE BUT THERE IS A LOW CHANCE FOR A PERIOD OF MVFR CIGS LATER THIS AFTERNOON. MDB/RODRIGUEZ //DISCUSSION...UPDATED 12Z... HIGH PRESSURE RIDGING HAS SHIFTED OFF TO THE EAST OF THE TERMINALS ALLOWING A STEADIER SOUTHERLY FLOW TO SET UP. AN UPPER LEVEL TROUGH IS CURRENTLY CROSSING THE AREA WITH ASSOCIATED PRECIP REMAINING NORTHEAST OF THE AREA. VFR CLOUD SHIELD WITH BASES OF 6000-7000 FT CONTINUES TO MOVE EASTWARD WITH THE BACK EDGE OF IT COMING INTO NORTH CENTRAL ILLINOIS. HAVE GONE AHEAD AND REDUCED CLOUD COVER OVER THE NEXT FEW HOURS AS SATELLITE SUPPORTS THIS CLOUD BAND EXITING TO THE EAST OF THE TERMINALS. COVERAGE COULD BE MUCH LESS THAN THE SCT INCLUDED IN THE TAFS BUT SOME ADDITIONAL CUMULUS COULD DEVELOP. SOUTH TO SOUTHWEST WINDS WILL CONTINUE THROUGH THE MORNING THEN TURN WEST AND THEN NORTHWEST WITH THE PASSAGE OF A COLD FRONTAL BOUNDARY THIS AFTERNOON. CLOUD COVER TO THE NORTH OF THE AREA LOOKS TO WORK SOUTHWARD INTO THE AREA LATER THIS AFTERNOON. EXPECT THE BULK OF THIS TO BE VFR BUT SOME MVFR MAY DEVELOP FOR A BRIEF PERIOD. WINDS WILL DIMINISH LATER THIS EVENING WHILE TRYING TO TURN MORE NORTHERLY OVERNIGHT WITH ANY LATE DAY CLOUD COVER EXITING THE AREA LEAVING LITTLE IN THE WAY OF SKY COVER GOING INTO FRIDAY MORNING. MDB //ORD AND MDW CONFIDENCE...UPDATED 16Z... * HIGH CONFIDENCE IN WIND FORECAST. * LOW CONFIDENCE IN MVFR POTENTIAL THIS AFTERNOON. MDB/RODRIGUEZ //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...VFR. SATURDAY...VFR. SUNDAY AND MONDAY...MVFR POSSIBLE, TUESDAY...VFR. WEDNESDAY...CHANCE SHRA...MVFR POSSIBLE. MDB && .MARINE... 221 AM CST THE MAIN FOCUS OF THE FORECAST CONTINUES TO BE THE POTENTIAL FOR GALE FORCE WINDS LATE FRIDAY NIGHT THROUGH MIDDAY/EARLY AFTERNOON SATURDAY...MAINLY ACROSS THE NORTH HALF OF THE LAKE. CURRENTLY...SURFACE LOW PRESSURE CONTINUES TO DEEPEN AS IT MOVES NORTHWARD INTO EASTERN QUEBEC AND NEWFOUNDLAND. HIGH PRESSURE RIDGING IS CROSSING LAKE MICHIGAN EARLY THIS MORNING WITH A WEAK AREA OF LOW PRESSURE OVER WESTERN MINNESOTA AND NORTHWEST IOWA. THIS LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATER TODAY AND THIS EVENING. WINDS HAVE TURNED WEST AND SOUTHWEST THANKS TO THE PASSAGE OF THE RIDGE AXIS WITH SPEEDS DIMINISHING BUT THEY WILL INCREASE SOMEWHAT AS THE LOW CROSSES THE AREA LATER TODAY. A NARROW CORRIDOR OF OFFSHORE SOUTHEASTERLY WINDS IS OCCURRING ALONG THE MICHIGAN SHORE BUT WILL DIMINISH THROUGH MID MORNING. WINDS ACROSS FAR NORTHERN LAKE MICHIGAN WILL BE TRICKY AS THE LOW CENTER IS EXPECTED TO CROSS THIS AREA THIS AFTERNOON. THIS WILL LIKELY LEAD TO AN EASTERLY SURFACE FLOW OVER FAR NORTHERN LAKE MICHIGAN LATER THIS MORNING AND THIS AFTERNOON...WHILE THE REST OF THE LAKE SEES WEST TO SOUTHWEST WINDS. A COOL FRONTAL BOUNDARY WILL CROSS THE LAKE LATER TODAY TURNING WINDS TO THE NORTHWEST. HIGH PRESSURE WILL SPREAD IN BEHIND THE FRONT AND STRENGTHEN AS IT CROSSES THE LAKE FRIDAY BEFORE SHIFTING TO THE EAST. THIS WILL TURN WINDS BACK TO THE SOUTH BY FRIDAY AFTERNOON WITH RATHER LIGHT SPEEDS. THE HIGH WILL CONTINUE TO STRENGTHEN AS IT MOVES ACROSS THE NORTHEAST U.S. WHILE A CLIPPER DROPS SOUTHEAST ACROSS WESTERN ONTARIO JUST NORTH OF LAKE SUPERIOR SATURDAY. THE PRESSURE GRADIENT WILL TIGHTEN BETWEEN THESE TWO SYSTEMS LEADING TO STRONG SOUTH TO SOUTHWEST WINDS LATE FRIDAY NIGHT AND SATURDAY MORNING. THE STRONGEST SPEEDS WILL OCCUR ACROSS NORTHERN PORTIONS OF THE LAKE. WILL HOLD WINDS TO 30 KT FOR NOW WITH THE STRONGEST WINDS NORTH...BUT AM CONCERNED THAT AN INCREASE TO GALES MAY BE NEEDED. THIS SYSTEM IS NOT TOO UNLIKE SEVERAL WHICH WE SAW EARLIER THIS FALL THAT FEATURED SURFACE LOWS PASSING TO THE NORTH AND WINDS THAT WERE HIGHER THAN EXPECTED. THIS MAY NOT BE THE CASE WITH THIS PARTICULAR SYSTEM BUT IT IS WORTH NOTING GIVEN THAT UNSTABLE CONDITIONS WILL BE IN PLACE ACROSS THE LAKE SIMILAR TO THESE EARLIER SYSTEMS. A COLD FRONT CROSSES THE LAKE SATURDAY AFTERNOON ALLOWING WINDS TO DROP OFF SATURDAY EVENING. ANOTHER AREA OF HIGH PRESSURE WILL MOVE ACROSS THE REGION SUNDAY AND CONTINUE TO KEEP LIGHTER WINDS IN PLACE THROUGH TUESDAY. FORECAST CONFIDENCE DROPS OFF BY WEDNESDAY BUT IT DOES APPEAR THAT A MORE ACTIVE PATTERN WILL BE SETTING UP BRINGING INCREASING CHANCES FOR STRONGER WINDS. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
810 AM CST THU NOV 28 2013 .DISCUSSION... 306 AM CST THE PRIMARY FORECAST CONCERNS ARE CENTERED ON CLOUD COVER AND TEMPERATURES THROUGH THE WEEKEND AND THEN CHANCES FOR PRECIPITATION NEXT WEEK IN WHAT APPEARS TO POSSIBLY BE AN UNSETTLED PATTERN...ALTHOUGH A HIGH DEGREE OF UNCERTAINTY. ONE MORE SHORT WAVE IS DIVING SOUTHEAST ACROSS THE GREAT LAKES THIS THANKSGIVING MORNING IN WHAT HAS BEEN A LITERAL PARADE OF THESE COLD-AIR-REINFORCING SYSTEMS. A 1017MB SURFACE LOW REFLECTION ACROSS IA WILL TRANSLATE EAST THIS MORNING AND WEAKEN AS IT DOES SUCH. MORNING CLOUDS IN PLACE WERE DEVELOPED WITHIN THE WARM AIR ADVECTION ENVELOPE OF THIS SYSTEM AND AS SUCH HAVE BASES MAINLY ABOVE 5000 FT...SO BELIEVE THEY WILL VACATE BY AFTERNOON ACROSS THE WESTERN AND SOUTHERN FORECAST AREA GIVEN THE CLOUD-BEARING WIND FLOW. LOW-LEVEL LAPSE RATES ARE MODESTLY STEEP BEHIND THE SYSTEM WITH SOME MARGINAL SATURATION FORECAST AT THE TOP OF THE MIXED LAYER...SO LIKELY SOME SCATTERED STRATOCU WILL CONTINUE. ALL-IN-ALL...EXPECTING SOME SUN LATE THIS MORNING AND AFTERNOON. GIVEN THE 850MB AND 925MB FORECAST TEMPS BY THE RAP AND NAM THIS AFTERNOON...WE ONCE AGAIN ARE IN THE BOTTOM TENTH PERCENTILE FOR THIS TIME OF YEAR. THIS FAVORS HIGHS IN THE LOWER TO MID 30S. SEE THE CLIMATE DISCUSSION BELOW FOR MORE ON WHERE THIS STACKS UP FOR THANKSGIVING DAYS. AS A CANADIAN SURFACE HIGH MOVES OVERHEAD TONIGHT TEMPERATURES SHOULD RADIATE QUICKLY THIS EVE...EVEN IF IT DOES TAKE A FEW HOURS AFTER SUNSET TO DIMINISH THE LINGERING STRATOCU. HAVE MID AND EVEN PATCHY LOWER TEENS IN OUTLYING AREAS. AS THE WIND FIELD OVER LAKE MI SHIFTS MORE NE TONIGHT IMMEDIATELY AHEAD OF THE HIGH CENTER...A LAKE PLUME OF AT LEAST CLOUDS LOOKS LIKELY INTO NORTHWEST INDIANA AND POSSIBLY NORTHEAST ILLINOIS. LAKE-INDUCED EQUILIBRIUM LEVELS AROUND 4500 FT FORECAST BY THE NAM SEEM A LITTLE SHALLOW FOR PRECIP AND ANY PRONOUNCED CONVERGENCE IS UNLIKELY. HAVE THUS ONLY ADDED A LOW CHANCE FOR SOME LIGHT SNOW IN NORTHWEST IN/FAR SOUTHEAST COOK COUNTY LATE TONIGHT AS WELL AS BUMPED UP CLOUD COVER. A MORE ZONAL PATTERN WILL MOVE OVER BY LATER FRIDAY INTO SATURDAY BRINGING MODERATING TEMPERATURES. THERE IS A FAIR AMOUNT OF SPREAD IN THE ENVELOPE OF GUIDANCE SOLUTIONS FOR HOW WARM SATURDAY WILL BE...AND POTENTIAL CLOUD COVER LIKELY HAS QUITE A BIT TO DO WITH THAT. THIS TIME OF YEAR SOUTHERLY LOW-LEVEL FLOW AFTER A COLD AIR MASS CAN READILY BECOME "CONTAMINATED" WITH SATURATION/CLOUDS. CLIMATOLOGY OF THE 850MB AND 925MB TEMPERATURES WOULD FAVOR MID AND MAYBE EVEN UPPER 40S...BUT THAT WARM CURRENTLY SEEMS UNLIKELY WITH AT LEAST SOME POTENTIAL FOR CLOUDS AND NOT THE STRONGEST OF WARM AIR ADVECTION SIGNALS. THE HEART OF THE SYSTEM IS OVER THE NORTHERN GREAT LAKES...SO FORCING AND SATURATION REMAINS MINIMAL OVER THE AREA. SO HAVE NO POPS AT THIS TIME. NEXT WEEK THE UNCERTAINTY REALLY STARTS TO RAMP UP BY MIDWEEK AFTER WHAT IS BECOMING A MORE FAVORED DRY SUNDAY AND MONDAY. ALTHOUGH MUCH LIKE SATURDAY...TEMPERATURE CONFIDENCE IS FAIRLY LOW GIVEN CLOUD POTENTIAL. IF CLOUDS ARE REMAINING INTO SUNDAY MORNING THEY VERY WELL COULD STICK AROUND ALL THE WAY THROUGH MONDAY NIGHT AS SURFACE PRESSURES ARE FORECAST TO BASICALLY REMAIN THE SAME...I.E. LITTLE ADVECTION. THE LONG ADVERTISED UPPER TROUGH ACROSS THE WEST COAST LOOKS TO EVOLVE IN THE BEGINNING OF THE WEEK AND FORCE DOWNSTREAM RIDGING AND SOUTHWEST FLOW ALOFT. THIS TROUGH SHOULD PACK QUITE A PUNCH OF COLD AIR INTO THE NORTHERN ROCKIES AND PLAINS...BUT THE MAIN BAROCLINIC ZONE DURING MIDWEEK LOOKS TO REMAIN TO THE NORTHWEST AND IF THAT IS THE CASE THEN ANY HEAVY WINTER PRECIP SHOULD AS WELL DURING MIDWEEK...BUT AGAIN CONFIDENCE IS LOW. ENERGY THAT TRANSLATES EAST FROM THIS TROUGH APPEARS TO BE IN PARTS AND THUS MULTIPLE CHANCES FOR PRECIP LOOK TO BE THE CASE ACROSS THE GREAT LAKES AND CORN BELT REGIONS DURING THE DEC 3-8 PERIOD. NIGHTTIME TEMPERATURES SHOULD BE MORE NEAR NORMAL OR EVEN ABOVE NORMAL GIVEN CLOUD COVER DURING MIDWEEK...BUT DAYTIME HIGHS COULD BE ANYWHERE IN A LARGE SPECTRUM OF SOLUTIONS DEPENDING ON STRENGTH OF SOUTHERLY FLOW AND WHEN LOW PASSAGES OCCUR. THOSE ARE BOTH VARIABLES DIFFICULT TO LOCK DOWN IN A FORECAST PATTERN OF A BROAD TROUGH IN THE WEST. MTF && .CLIMATE... 306 AM CST THE FORECAST HIGH TODAY FOR CHICAGO (O`HARE) IS 33 WHICH WOULD TIE MULTIPLE THANKSGIVINGS IN THE PAST TWO DECADES FOR A COOL HIGH...THE LAST BEING 2007. HOWEVER IF THE MERCURY STAYS BELOW THAT...IT WOULD BE THE COLDEST HIGH TEMPERATURE ON THANKSGIVING IN CHICAGO SINCE 1989. SIMILARLY FOR ROCKFORD...THE 31 DEGREE FORECAST HIGH WOULD BE THE COOLEST THANKSGIVING HIGH SINCE 1995 AND IF IT STAYS BELOW THAT IT WOULD BE THE COOLEST SINCE 1989. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * WIND SHIFT FROM SOUTHWEST TO NORTHWEST TOWARD 20Z. * VFR EXPECTED TO CONTINUE BUT THERE IS A LOW CHANCE FOR A PERIOD OF MVFR CIGS LATER THIS AFTERNOON. MDB/RODRIGUEZ //DISCUSSION...UPDATED 12Z... HIGH PRESSURE RIDGING HAS SHIFTED OFF TO THE EAST OF THE TERMINALS ALLOWING A STEADIER SOUTHERLY FLOW TO SET UP. AN UPPER LEVEL TROUGH IS CURRENTLY CROSSING THE AREA WITH ASSOCIATED PRECIP REMAINING NORTHEAST OF THE AREA. VFR CLOUD SHIELD WITH BASES OF 6000-7000 FT CONTINUES TO MOVE EASTWARD WITH THE BACK EDGE OF IT COMING INTO NORTH CENTRAL ILLINOIS. HAVE GONE AHEAD AND REDUCED CLOUD COVER OVER THE NEXT FEW HOURS AS SATELLITE SUPPORTS THIS CLOUD BAND EXITING TO THE EAST OF THE TERMINALS. COVERAGE COULD BE MUCH LESS THAN THE SCT INCLUDED IN THE TAFS BUT SOME ADDITIONAL CUMULUS COULD DEVELOP. SOUTH TO SOUTHWEST WINDS WILL CONTINUE THROUGH THE MORNING THEN TURN WEST AND THEN NORTHWEST WITH THE PASSAGE OF A COLD FRONTAL BOUNDARY THIS AFTERNOON. CLOUD COVER TO THE NORTH OF THE AREA LOOKS TO WORK SOUTHWARD INTO THE AREA LATER THIS AFTERNOON. EXPECT THE BULK OF THIS TO BE VFR BUT SOME MVFR MAY DEVELOP FOR A BRIEF PERIOD. WINDS WILL DIMINISH LATER THIS EVENING WHILE TRYING TO TURN MORE NORTHERLY OVERNIGHT WITH ANY LATE DAY CLOUD COVER EXITING THE AREA LEAVING LITTLE IN THE WAY OF SKY COVER GOING INTO FRIDAY MORNING. MDB //ORD AND MDW CONFIDENCE...UPDATED 14Z... * HIGH CONFIDENCE IN WIND FORECAST. * LOW CONFIDENCE IN MVFR POTENTIAL THIS AFTERNOON. MDB/RODRIGUEZ //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...VFR. SATURDAY...VFR. SUNDAY AND MONDAY...MVFR POSSIBLE, TUESDAY...VFR. WEDNESDAY...CHANCE SHRA...MVFR POSSIBLE. MDB && .MARINE... 221 AM CST THE MAIN FOCUS OF THE FORECAST CONTINUES TO BE THE POTENTIAL FOR GALE FORCE WINDS LATE FRIDAY NIGHT THROUGH MIDDAY/EARLY AFTERNOON SATURDAY...MAINLY ACROSS THE NORTH HALF OF THE LAKE. CURRENTLY...SURFACE LOW PRESSURE CONTINUES TO DEEPEN AS IT MOVES NORTHWARD INTO EASTERN QUEBEC AND NEWFOUNDLAND. HIGH PRESSURE RIDGING IS CROSSING LAKE MICHIGAN EARLY THIS MORNING WITH A WEAK AREA OF LOW PRESSURE OVER WESTERN MINNESOTA AND NORTHWEST IOWA. THIS LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATER TODAY AND THIS EVENING. WINDS HAVE TURNED WEST AND SOUTHWEST THANKS TO THE PASSAGE OF THE RIDGE AXIS WITH SPEEDS DIMINISHING BUT THEY WILL INCREASE SOMEWHAT AS THE LOW CROSSES THE AREA LATER TODAY. A NARROW CORRIDOR OF OFFSHORE SOUTHEASTERLY WINDS IS OCCURRING ALONG THE MICHIGAN SHORE BUT WILL DIMINISH THROUGH MID MORNING. WINDS ACROSS FAR NORTHERN LAKE MICHIGAN WILL BE TRICKY AS THE LOW CENTER IS EXPECTED TO CROSS THIS AREA THIS AFTERNOON. THIS WILL LIKELY LEAD TO AN EASTERLY SURFACE FLOW OVER FAR NORTHERN LAKE MICHIGAN LATER THIS MORNING AND THIS AFTERNOON...WHILE THE REST OF THE LAKE SEES WEST TO SOUTHWEST WINDS. A COOL FRONTAL BOUNDARY WILL CROSS THE LAKE LATER TODAY TURNING WINDS TO THE NORTHWEST. HIGH PRESSURE WILL SPREAD IN BEHIND THE FRONT AND STRENGTHEN AS IT CROSSES THE LAKE FRIDAY BEFORE SHIFTING TO THE EAST. THIS WILL TURN WINDS BACK TO THE SOUTH BY FRIDAY AFTERNOON WITH RATHER LIGHT SPEEDS. THE HIGH WILL CONTINUE TO STRENGTHEN AS IT MOVES ACROSS THE NORTHEAST U.S. WHILE A CLIPPER DROPS SOUTHEAST ACROSS WESTERN ONTARIO JUST NORTH OF LAKE SUPERIOR SATURDAY. THE PRESSURE GRADIENT WILL TIGHTEN BETWEEN THESE TWO SYSTEMS LEADING TO STRONG SOUTH TO SOUTHWEST WINDS LATE FRIDAY NIGHT AND SATURDAY MORNING. THE STRONGEST SPEEDS WILL OCCUR ACROSS NORTHERN PORTIONS OF THE LAKE. WILL HOLD WINDS TO 30 KT FOR NOW WITH THE STRONGEST WINDS NORTH...BUT AM CONCERNED THAT AN INCREASE TO GALES MAY BE NEEDED. THIS SYSTEM IS NOT TOO UNLIKE SEVERAL WHICH WE SAW EARLIER THIS FALL THAT FEATURED SURFACE LOWS PASSING TO THE NORTH AND WINDS THAT WERE HIGHER THAN EXPECTED. THIS MAY NOT BE THE CASE WITH THIS PARTICULAR SYSTEM BUT IT IS WORTH NOTING GIVEN THAT UNSTABLE CONDITIONS WILL BE IN PLACE ACROSS THE LAKE SIMILAR TO THESE EARLIER SYSTEMS. A COLD FRONT CROSSES THE LAKE SATURDAY AFTERNOON ALLOWING WINDS TO DROP OFF SATURDAY EVENING. ANOTHER AREA OF HIGH PRESSURE WILL MOVE ACROSS THE REGION SUNDAY AND CONTINUE TO KEEP LIGHTER WINDS IN PLACE THROUGH TUESDAY. FORECAST CONFIDENCE DROPS OFF BY WEDNESDAY BUT IT DOES APPEAR THAT A MORE ACTIVE PATTERN WILL BE SETTING UP BRINGING INCREASING CHANCES FOR STRONGER WINDS. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
540 AM CST THU NOV 28 2013 .DISCUSSION... 306 AM CST THE PRIMARY FORECAST CONCERNS ARE CENTERED ON CLOUD COVER AND TEMPERATURES THROUGH THE WEEKEND AND THEN CHANCES FOR PRECIPITATION NEXT WEEK IN WHAT APPEARS TO POSSIBLY BE AN UNSETTLED PATTERN...ALTHOUGH A HIGH DEGREE OF UNCERTAINTY. ONE MORE SHORT WAVE IS DIVING SOUTHEAST ACROSS THE GREAT LAKES THIS THANKSGIVING MORNING IN WHAT HAS BEEN A LITERAL PARADE OF THESE COLD-AIR-REINFORCING SYSTEMS. A 1017MB SURFACE LOW REFLECTION ACROSS IA WILL TRANSLATE EAST THIS MORNING AND WEAKEN AS IT DOES SUCH. MORNING CLOUDS IN PLACE WERE DEVELOPED WITHIN THE WARM AIR ADVECTION ENVELOPE OF THIS SYSTEM AND AS SUCH HAVE BASES MAINLY ABOVE 5000 FT...SO BELIEVE THEY WILL VACATE BY AFTERNOON ACROSS THE WESTERN AND SOUTHERN FORECAST AREA GIVEN THE CLOUD-BEARING WIND FLOW. LOW-LEVEL LAPSE RATES ARE MODESTLY STEEP BEHIND THE SYSTEM WITH SOME MARGINAL SATURATION FORECAST AT THE TOP OF THE MIXED LAYER...SO LIKELY SOME SCATTERED STRATOCU WILL CONTINUE. ALL-IN-ALL...EXPECTING SOME SUN LATE THIS MORNING AND AFTERNOON. GIVEN THE 850MB AND 925MB FORECAST TEMPS BY THE RAP AND NAM THIS AFTERNOON...WE ONCE AGAIN ARE IN THE BOTTOM TENTH PERCENTILE FOR THIS TIME OF YEAR. THIS FAVORS HIGHS IN THE LOWER TO MID 30S. SEE THE CLIMATE DISCUSSION BELOW FOR MORE ON WHERE THIS STACKS UP FOR THANKSGIVING DAYS. AS A CANADIAN SURFACE HIGH MOVES OVERHEAD TONIGHT TEMPERATURES SHOULD RADIATE QUICKLY THIS EVE...EVEN IF IT DOES TAKE A FEW HOURS AFTER SUNSET TO DIMINISH THE LINGERING STRATOCU. HAVE MID AND EVEN PATCHY LOWER TEENS IN OUTLYING AREAS. AS THE WIND FIELD OVER LAKE MI SHIFTS MORE NE TONIGHT IMMEDIATELY AHEAD OF THE HIGH CENTER...A LAKE PLUME OF AT LEAST CLOUDS LOOKS LIKELY INTO NORTHWEST INDIANA AND POSSIBLY NORTHEAST ILLINOIS. LAKE-INDUCED EQUILIBRIUM LEVELS AROUND 4500 FT FORECAST BY THE NAM SEEM A LITTLE SHALLOW FOR PRECIP AND ANY PRONOUNCED CONVERGENCE IS UNLIKELY. HAVE THUS ONLY ADDED A LOW CHANCE FOR SOME LIGHT SNOW IN NORTHWEST IN/FAR SOUTHEAST COOK COUNTY LATE TONIGHT AS WELL AS BUMPED UP CLOUD COVER. A MORE ZONAL PATTERN WILL MOVE OVER BY LATER FRIDAY INTO SATURDAY BRINGING MODERATING TEMPERATURES. THERE IS A FAIR AMOUNT OF SPREAD IN THE ENVELOPE OF GUIDANCE SOLUTIONS FOR HOW WARM SATURDAY WILL BE...AND POTENTIAL CLOUD COVER LIKELY HAS QUITE A BIT TO DO WITH THAT. THIS TIME OF YEAR SOUTHERLY LOW-LEVEL FLOW AFTER A COLD AIR MASS CAN READILY BECOME "CONTAMINATED" WITH SATURATION/CLOUDS. CLIMATOLOGY OF THE 850MB AND 925MB TEMPERATURES WOULD FAVOR MID AND MAYBE EVEN UPPER 40S...BUT THAT WARM CURRENTLY SEEMS UNLIKELY WITH AT LEAST SOME POTENTIAL FOR CLOUDS AND NOT THE STRONGEST OF WARM AIR ADVECTION SIGNALS. THE HEART OF THE SYSTEM IS OVER THE NORTHERN GREAT LAKES...SO FORCING AND SATURATION REMAINS MINIMAL OVER THE AREA. SO HAVE NO POPS AT THIS TIME. NEXT WEEK THE UNCERTAINTY REALLY STARTS TO RAMP UP BY MIDWEEK AFTER WHAT IS BECOMING A MORE FAVORED DRY SUNDAY AND MONDAY. ALTHOUGH MUCH LIKE SATURDAY...TEMPERATURE CONFIDENCE IS FAIRLY LOW GIVEN CLOUD POTENTIAL. IF CLOUDS ARE REMAINING INTO SUNDAY MORNING THEY VERY WELL COULD STICK AROUND ALL THE WAY THROUGH MONDAY NIGHT AS SURFACE PRESSURES ARE FORECAST TO BASICALLY REMAIN THE SAME...I.E. LITTLE ADVECTION. THE LONG ADVERTISED UPPER TROUGH ACROSS THE WEST COAST LOOKS TO EVOLVE IN THE BEGINNING OF THE WEEK AND FORCE DOWNSTREAM RIDGING AND SOUTHWEST FLOW ALOFT. THIS TROUGH SHOULD PACK QUITE A PUNCH OF COLD AIR INTO THE NORTHERN ROCKIES AND PLAINS...BUT THE MAIN BAROCLINIC ZONE DURING MIDWEEK LOOKS TO REMAIN TO THE NORTHWEST AND IF THAT IS THE CASE THEN ANY HEAVY WINTER PRECIP SHOULD AS WELL DURING MIDWEEK...BUT AGAIN CONFIDENCE IS LOW. ENERGY THAT TRANSLATES EAST FROM THIS TROUGH APPEARS TO BE IN PARTS AND THUS MULTIPLE CHANCES FOR PRECIP LOOK TO BE THE CASE ACROSS THE GREAT LAKES AND CORN BELT REGIONS DURING THE DEC 3-8 PERIOD. NIGHTTIME TEMPERATURES SHOULD BE MORE NEAR NORMAL OR EVEN ABOVE NORMAL GIVEN CLOUD COVER DURING MIDWEEK...BUT DAYTIME HIGHS COULD BE ANYWHERE IN A LARGE SPECTRUM OF SOLUTIONS DEPENDING ON STRENGTH OF SOUTHERLY FLOW AND WHEN LOW PASSAGES OCCUR. THOSE ARE BOTH VARIABLES DIFFICULT TO LOCK DOWN IN A FORECAST PATTERN OF A BROAD TROUGH IN THE WEST. MTF && .CLIMATE... 306 AM CST THE FORECAST HIGH TODAY FOR CHICAGO (O`HARE) IS 33 WHICH WOULD TIE MULTIPLE THANKSGIVINGS IN THE PAST TWO DECADES FOR A COOL HIGH...THE LAST BEING 2007. HOWEVER IF THE MERCURY STAYS BELOW THAT...IT WOULD BE THE COLDEST HIGH TEMPERATURE ON THANKSGIVING IN CHICAGO SINCE 1989. SIMILARLY FOR ROCKFORD...THE 31 DEGREE FORECAST HIGH WOULD BE THE COOLEST THANKSGIVING HIGH SINCE 1995 AND IF IT STAYS BELOW THAT IT WOULD BE THE COOLEST SINCE 1989. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * WINDS SHIFT FROM SOUTHWEST TO NORTHWEST TOWARD 20Z. * VFR EXPECTED TO CONTINUE BUT THERE IS A LOW CHANCE FOR A PERIOD OF MVFR CIGS LATER THIS AFTERNOON. MDB //DISCUSSION...UPDATED 12Z... HIGH PRESSURE RIDGING HAS SHIFTED OFF TO THE EAST OF THE TERMINALS ALLOWING A STEADIER SOUTHERLY FLOW TO SET UP. AN UPPER LEVEL TROUGH IS CURRENTLY CROSSING THE AREA WITH ASSOCIATED PRECIP REMAINING NORTHEAST OF THE AREA. VFR CLOUD SHIELD WITH BASES OF 6000-7000 FT CONTINUES TO MOVE EASTWARD WITH THE BACK EDGE OF IT COMING INTO NORTH CENTRAL ILLINOIS. HAVE GONE AHEAD AND REDUCED CLOUD COVER OVER THE NEXT FEW HOURS AS SATELLITE SUPPORTS THIS CLOUD BAND EXITING TO THE EAST OF THE TERMINALS. COVERAGE COULD BE MUCH LESS THAN THE SCT INCLUDED IN THE TAFS BUT SOME ADDITIONAL CUMULUS COULD DEVELOP. SOUTH TO SOUTHWEST WINDS WILL CONTINUE THROUGH THE MORNING THEN TURN WEST AND THEN NORTHWEST WITH THE PASSAGE OF A COLD FRONTAL BOUNDARY THIS AFTERNOON. CLOUD COVER TO THE NORTH OF THE AREA LOOKS TO WORK SOUTHWARD INTO THE AREA LATER THIS AFTERNOON. EXPECT THE BULK OF THIS TO BE VFR BUT SOME MVFR MAY DEVELOP FOR A BRIEF PERIOD. WINDS WILL DIMINISH LATER THIS EVENING WHILE TRYING TO TURN MORE NORTHERLY OVERNIGHT WITH ANY LATE DAY CLOUD COVER EXITING THE AREA LEAVING LITTLE IN THE WAY OF SKY COVER GOING INTO FRIDAY MORNING. MDB //ORD AND MDW CONFIDENCE...UPDATED 12Z... * HIGH CONFIDENCE IN WIND FORECAST. * LOW CONFIDENCE IN MVFR POTENTIAL THIS AFTERNOON. MDB //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...VFR. SATURDAY...VFR. SUNDAY AND MONDAY...MVFR POSSIBLE, TUESDAY...VFR. WEDNESDAY...CHANCE SHRA...MVFR POSSIBLE. MDB && .MARINE... 221 AM CST THE MAIN FOCUS OF THE FORECAST CONTINUES TO BE THE POTENTIAL FOR GALE FORCE WINDS LATE FRIDAY NIGHT THROUGH MIDDAY/EARLY AFTERNOON SATURDAY...MAINLY ACROSS THE NORTH HALF OF THE LAKE. CURRENTLY...SURFACE LOW PRESSURE CONTINUES TO DEEPEN AS IT MOVES NORTHWARD INTO EASTERN QUEBEC AND NEWFOUNDLAND. HIGH PRESSURE RIDGING IS CROSSING LAKE MICHIGAN EARLY THIS MORNING WITH A WEAK AREA OF LOW PRESSURE OVER WESTERN MINNESOTA AND NORTHWEST IOWA. THIS LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATER TODAY AND THIS EVENING. WINDS HAVE TURNED WEST AND SOUTHWEST THANKS TO THE PASSAGE OF THE RIDGE AXIS WITH SPEEDS DIMINISHING BUT THEY WILL INCREASE SOMEWHAT AS THE LOW CROSSES THE AREA LATER TODAY. A NARROW CORRIDOR OF OFFSHORE SOUTHEASTERLY WINDS IS OCCURRING ALONG THE MICHIGAN SHORE BUT WILL DIMINISH THROUGH MID MORNING. WINDS ACROSS FAR NORTHERN LAKE MICHIGAN WILL BE TRICKY AS THE LOW CENTER IS EXPECTED TO CROSS THIS AREA THIS AFTERNOON. THIS WILL LIKELY LEAD TO AN EASTERLY SURFACE FLOW OVER FAR NORTHERN LAKE MICHIGAN LATER THIS MORNING AND THIS AFTERNOON...WHILE THE REST OF THE LAKE SEES WEST TO SOUTHWEST WINDS. A COOL FRONTAL BOUNDARY WILL CROSS THE LAKE LATER TODAY TURNING WINDS TO THE NORTHWEST. HIGH PRESSURE WILL SPREAD IN BEHIND THE FRONT AND STRENGTHEN AS IT CROSSES THE LAKE FRIDAY BEFORE SHIFTING TO THE EAST. THIS WILL TURN WINDS BACK TO THE SOUTH BY FRIDAY AFTERNOON WITH RATHER LIGHT SPEEDS. THE HIGH WILL CONTINUE TO STRENGTHEN AS IT MOVES ACROSS THE NORTHEAST U.S. WHILE A CLIPPER DROPS SOUTHEAST ACROSS WESTERN ONTARIO JUST NORTH OF LAKE SUPERIOR SATURDAY. THE PRESSURE GRADIENT WILL TIGHTEN BETWEEN THESE TWO SYSTEMS LEADING TO STRONG SOUTH TO SOUTHWEST WINDS LATE FRIDAY NIGHT AND SATURDAY MORNING. THE STRONGEST SPEEDS WILL OCCUR ACROSS NORTHERN PORTIONS OF THE LAKE. WILL HOLD WINDS TO 30 KT FOR NOW WITH THE STRONGEST WINDS NORTH...BUT AM CONCERNED THAT AN INCREASE TO GALES MAY BE NEEDED. THIS SYSTEM IS NOT TOO UNLIKE SEVERAL WHICH WE SAW EARLIER THIS FALL THAT FEATURED SURFACE LOWS PASSING TO THE NORTH AND WINDS THAT WERE HIGHER THAN EXPECTED. THIS MAY NOT BE THE CASE WITH THIS PARTICULAR SYSTEM BUT IT IS WORTH NOTING GIVEN THAT UNSTABLE CONDITIONS WILL BE IN PLACE ACROSS THE LAKE SIMILAR TO THESE EARLIER SYSTEMS. A COLD FRONT CROSSES THE LAKE SATURDAY AFTERNOON ALLOWING WINDS TO DROP OFF SATURDAY EVENING. ANOTHER AREA OF HIGH PRESSURE WILL MOVE ACROSS THE REGION SUNDAY AND CONTINUE TO KEEP LIGHTER WINDS IN PLACE THROUGH TUESDAY. FORECAST CONFIDENCE DROPS OFF BY WEDNESDAY BUT IT DOES APPEAR THAT A MORE ACTIVE PATTERN WILL BE SETTING UP BRINGING INCREASING CHANCES FOR STRONGER WINDS. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
310 AM CST THU NOV 28 2013 .DISCUSSION... 306 AM CST THE PRIMARY FORECAST CONCERNS ARE CENTERED ON CLOUD COVER AND TEMPERATURES THROUGH THE WEEKEND AND THEN CHANCES FOR PRECIPITATION NEXT WEEK IN WHAT APPEARS TO POSSIBLY BE AN UNSETTLED PATTERN...ALTHOUGH A HIGH DEGREE OF UNCERTAINTY. ONE MORE SHORT WAVE IS DIVING SOUTHEAST ACROSS THE GREAT LAKES THIS THANKSGIVING MORNING IN WHAT HAS BEEN A LITERAL PARADE OF THESE COLD-AIR-REINFORCING SYSTEMS. A 1017MB SURFACE LOW REFLECTION ACROSS IA WILL TRANSLATE EAST THIS MORNING AND WEAKEN AS IT DOES SUCH. MORNING CLOUDS IN PLACE WERE DEVELOPED WITHIN THE WARM AIR ADVECTION ENVELOPE OF THIS SYSTEM AND AS SUCH HAVE BASES MAINLY ABOVE 5000 FT...SO BELIEVE THEY WILL VACATE BY AFTERNOON ACROSS THE WESTERN AND SOUTHERN FORECAST AREA GIVEN THE CLOUD-BEARING WIND FLOW. LOW-LEVEL LAPSE RATES ARE MODESTLY STEEP BEHIND THE SYSTEM WITH SOME MARGINAL SATURATION FORECAST AT THE TOP OF THE MIXED LAYER...SO LIKELY SOME SCATTERED STRATOCU WILL CONTINUE. ALL-IN-ALL...EXPECTING SOME SUN LATE THIS MORNING AND AFTERNOON. GIVEN THE 850MB AND 925MB FORECAST TEMPS BY THE RAP AND NAM THIS AFTERNOON...WE ONCE AGAIN ARE IN THE BOTTOM TENTH PERCENTILE FOR THIS TIME OF YEAR. THIS FAVORS HIGHS IN THE LOWER TO MID 30S. SEE THE CLIMATE DISCUSSION BELOW FOR MORE ON WHERE THIS STACKS UP FOR THANKSGIVING DAYS. AS A CANADIAN SURFACE HIGH MOVES OVERHEAD TONIGHT TEMPERATURES SHOULD RADIATE QUICKLY THIS EVE...EVEN IF IT DOES TAKE A FEW HOURS AFTER SUNSET TO DIMINISH THE LINGERING STRATOCU. HAVE MID AND EVEN PATCHY LOWER TEENS IN OUTLYING AREAS. AS THE WIND FIELD OVER LAKE MI SHIFTS MORE NE TONIGHT IMMEDIATELY AHEAD OF THE HIGH CENTER...A LAKE PLUME OF AT LEAST CLOUDS LOOKS LIKELY INTO NORTHWEST INDIANA AND POSSIBLY NORTHEAST ILLINOIS. LAKE-INDUCED EQUILIBRIUM LEVELS AROUND 4500 FT FORECAST BY THE NAM SEEM A LITTLE SHALLOW FOR PRECIP AND ANY PRONOUNCED CONVERGENCE IS UNLIKELY. HAVE THUS ONLY ADDED A LOW CHANCE FOR SOME LIGHT SNOW IN NORTHWEST IN/FAR SOUTHEAST COOK COUNTY LATE TONIGHT AS WELL AS BUMPED UP CLOUD COVER. A MORE ZONAL PATTERN WILL MOVE OVER BY LATER FRIDAY INTO SATURDAY BRINGING MODERATING TEMPERATURES. THERE IS A FAIR AMOUNT OF SPREAD IN THE ENVELOPE OF GUIDANCE SOLUTIONS FOR HOW WARM SATURDAY WILL BE...AND POTENTIAL CLOUD COVER LIKELY HAS QUITE A BIT TO DO WITH THAT. THIS TIME OF YEAR SOUTHERLY LOW-LEVEL FLOW AFTER A COLD AIR MASS CAN READILY BECOME "CONTAMINATED" WITH SATURATION/CLOUDS. CLIMATOLOGY OF THE 850MB AND 925MB TEMPERATURES WOULD FAVOR MID AND MAYBE EVEN UPPER 40S...BUT THAT WARM CURRENTLY SEEMS UNLIKELY WITH AT LEAST SOME POTENTIAL FOR CLOUDS AND NOT THE STRONGEST OF WARM AIR ADVECTION SIGNALS. THE HEART OF THE SYSTEM IS OVER THE NORTHERN GREAT LAKES...SO FORCING AND SATURATION REMAINS MINIMAL OVER THE AREA. SO HAVE NO POPS AT THIS TIME. NEXT WEEK THE UNCERTAINTY REALLY STARTS TO RAMP UP BY MIDWEEK AFTER WHAT IS BECOMING A MORE FAVORED DRY SUNDAY AND MONDAY. ALTHOUGH MUCH LIKE SATURDAY...TEMPERATURE CONFIDENCE IS FAIRLY LOW GIVEN CLOUD POTENTIAL. IF CLOUDS ARE REMAINING INTO SUNDAY MORNING THEY VERY WELL COULD STICK AROUND ALL THE WAY THROUGH MONDAY NIGHT AS SURFACE PRESSURES ARE FORECAST TO BASICALLY REMAIN THE SAME...I.E. LITTLE ADVECTION. THE LONG ADVERTISED UPPER TROUGH ACROSS THE WEST COAST LOOKS TO EVOLVE IN THE BEGINNING OF THE WEEK AND FORCE DOWNSTREAM RIDGING AND SOUTHWEST FLOW ALOFT. THIS TROUGH SHOULD PACK QUITE A PUNCH OF COLD AIR INTO THE NORTHERN ROCKIES AND PLAINS...BUT THE MAIN BAROCLINIC ZONE DURING MIDWEEK LOOKS TO REMAIN TO THE NORTHWEST AND IF THAT IS THE CASE THEN ANY HEAVY WINTER PRECIP SHOULD AS WELL DURING MIDWEEK...BUT AGAIN CONFIDENCE IS LOW. ENERGY THAT TRANSLATES EAST FROM THIS TROUGH APPEARS TO BE IN PARTS AND THUS MULTIPLE CHANCES FOR PRECIP LOOK TO BE THE CASE ACROSS THE GREAT LAKES AND CORN BELT REGIONS DURING THE DEC 3-8 PERIOD. NIGHTTIME TEMPERATURES SHOULD BE MORE NEAR NORMAL OR EVEN ABOVE NORMAL GIVEN CLOUD COVER DURING MIDWEEK...BUT DAYTIME HIGHS COULD BE ANYWHERE IN A LARGE SPECTRUM OF SOLUTIONS DEPENDING ON STRENGTH OF SOUTHERLY FLOW AND WHEN LOW PASSAGES OCCUR. THOSE ARE BOTH VARIABLES DIFFICULT TO LOCK DOWN IN A FORECAST PATTERN OF A BROAD TROUGH IN THE WEST. MTF && .CLIMATE... 306 AM CST THE FORECAST HIGH TODAY FOR CHICAGO (O`HARE) IS 33 WHICH WOULD TIE MULTIPLE THANKSGIVINGS IN THE PAST TWO DECADES FOR A COOL HIGH...THE LAST BEING 2007. HOWEVER IF THE MERCURY STAYS BELOW THAT...IT WOULD BE THE COLDEST HIGH TEMPERATURE ON THANKSGIVING IN CHICAGO SINCE 1989. SIMILARLY FOR ROCKFORD...THE 31 DEGREE FORECAST HIGH WOULD BE THE COOLEST THANKSGIVING HIGH SINCE 1995 AND IF IT STAYS BELOW THAT IT WOULD BE THE COOLEST SINCE 1989. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * WIND SHIFT FROM SOUTHWEST TO NORTHWEST TOWARD 21Z WITH COLD FRONTAL PASSAGE. * CHANCE FOR BRIEF PERIOD OF MVFR CIGS MID TO LATE AFTERNOON. MDB //DISCUSSION...UPDATED 06Z... HIGH PRESSURE RIDGING IS CROSSING THE AREA TONIGHT ALLOWING FOR LIGHT SOUTHWEST WINDS TO SET UP ACROSS THE TERMINALS. WINDS WILL LIKELY TURN MORE TO THE SOUTH LATER TONIGHT AS THE RIDGE SHIFTS EAST AND A WEAK LOW APPROACHES FROM THE WEST. AN UPPER LEVEL TROUGH WILL PASS NORTH OF THE AREA THROUGH THE MORNING BUT ASSOCIATED MVFR CIGS AND SNOW SHOWERS WILL REMAIN NORTH OF THE TERMINALS. BEYOND THAT...A COLD FRONT WILL BE DRAGGED ACROSS THE AREA WITH THE SURFACE LOW WHICH WILL TURN WINDS TO THE NORTHWEST DURING THE EARLY TO MID AFTERNOON HOURS. THERE WILL BE AT LEAST SOME CHANCE FOR A BAND OF MVFR CIGS TO ACCOMPANY THE FRONTAL PASSAGE SO WILL NEED TO MONITOR THE EXTENT SHOULD IT DEVELOP HOWEVER THE DURATION LOOKS TO BE RATHER SHORT IF IT DOES. HIGH PRESSURE WILL THEN MOVE IN INTO FRIDAY MORNING ALLOWING FOR LIGHT NORTHERLY WINDS. MDB //ORD AND MDW CONFIDENCE...UPDATED 09Z... * HIGH CONFIDENCE IN WIND FORECAST. * LOW-MEDIUM CONFIDENCE THAT SOME MVFR CIGS WILL DEVELOP DURING THE AFTERNOON. MDB //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY AND SATURDAY...VFR. SUNDAY AND MONDAY...MVFR CIG POSSIBLE. TUESDAY...VFR. ALLSOPP && .MARINE... 221 AM CST THE MAIN FOCUS OF THE FORECAST CONTINUES TO BE THE POTENTIAL FOR GALE FORCE WINDS LATE FRIDAY NIGHT THROUGH MIDDAY/EARLY AFTERNOON SATURDAY...MAINLY ACROSS THE NORTH HALF OF THE LAKE. CURRENTLY...SURFACE LOW PRESSURE CONTINUES TO DEEPEN AS IT MOVES NORTHWARD INTO EASTERN QUEBEC AND NEWFOUNDLAND. HIGH PRESSURE RIDGING IS CROSSING LAKE MICHIGAN EARLY THIS MORNING WITH A WEAK AREA OF LOW PRESSURE OVER WESTERN MINNESOTA AND NORTHWEST IOWA. THIS LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATER TODAY AND THIS EVENING. WINDS HAVE TURNED WEST AND SOUTHWEST THANKS TO THE PASSAGE OF THE RIDGE AXIS WITH SPEEDS DIMINISHING BUT THEY WILL INCREASE SOMEWHAT AS THE LOW CROSSES THE AREA LATER TODAY. A NARROW CORRIDOR OF OFFSHORE SOUTHEASTERLY WINDS IS OCCURRING ALONG THE MICHIGAN SHORE BUT WILL DIMINISH THROUGH MID MORNING. WINDS ACROSS FAR NORTHERN LAKE MICHIGAN WILL BE TRICKY AS THE LOW CENTER IS EXPECTED TO CROSS THIS AREA THIS AFTERNOON. THIS WILL LIKELY LEAD TO AN EASTERLY SURFACE FLOW OVER FAR NORTHERN LAKE MICHIGAN LATER THIS MORNING AND THIS AFTERNOON...WHILE THE REST OF THE LAKE SEES WEST TO SOUTHWEST WINDS. A COOL FRONTAL BOUNDARY WILL CROSS THE LAKE LATER TODAY TURNING WINDS TO THE NORTHWEST. HIGH PRESSURE WILL SPREAD IN BEHIND THE FRONT AND STRENGTHEN AS IT CROSSES THE LAKE FRIDAY BEFORE SHIFTING TO THE EAST. THIS WILL TURN WINDS BACK TO THE SOUTH BY FRIDAY AFTERNOON WITH RATHER LIGHT SPEEDS. THE HIGH WILL CONTINUE TO STRENGTHEN AS IT MOVES ACROSS THE NORTHEAST U.S. WHILE A CLIPPER DROPS SOUTHEAST ACROSS WESTERN ONTARIO JUST NORTH OF LAKE SUPERIOR SATURDAY. THE PRESSURE GRADIENT WILL TIGHTEN BETWEEN THESE TWO SYSTEMS LEADING TO STRONG SOUTH TO SOUTHWEST WINDS LATE FRIDAY NIGHT AND SATURDAY MORNING. THE STRONGEST SPEEDS WILL OCCUR ACROSS NORTHERN PORTIONS OF THE LAKE. WILL HOLD WINDS TO 30 KT FOR NOW WITH THE STRONGEST WINDS NORTH...BUT AM CONCERNED THAT AN INCREASE TO GALES MAY BE NEEDED. THIS SYSTEM IS NOT TOO UNLIKE SEVERAL WHICH WE SAW EARLIER THIS FALL THAT FEATURED SURFACE LOWS PASSING TO THE NORTH AND WINDS THAT WERE HIGHER THAN EXPECTED. THIS MAY NOT BE THE CASE WITH THIS PARTICULAR SYSTEM BUT IT IS WORTH NOTING GIVEN THAT UNSTABLE CONDITIONS WILL BE IN PLACE ACROSS THE LAKE SIMILAR TO THESE EARLIER SYSTEMS. A COLD FRONT CROSSES THE LAKE SATURDAY AFTERNOON ALLOWING WINDS TO DROP OFF SATURDAY EVENING. ANOTHER AREA OF HIGH PRESSURE WILL MOVE ACROSS THE REGION SUNDAY AND CONTINUE TO KEEP LIGHTER WINDS IN PLACE THROUGH TUESDAY. FORECAST CONFIDENCE DROPS OFF BY WEDNESDAY BUT IT DOES APPEAR THAT A MORE ACTIVE PATTERN WILL BE SETTING UP BRINGING INCREASING CHANCES FOR STRONGER WINDS. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM THURSDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
314 PM CST THU NOV 28 2013 .SYNOPSIS... ISSUED AT 218 PM CST THU NOV 28 2013 A WEAK SURFACE LOW MOVED EASTWARD INTO SOUTHERN LAKE MICHIGAN DURING THE DAY ON THURSDAY WITH A COLD FRONT STRETCHING SOUTHWESTWARD TO KSTL TO KJLN IN SOUTHWEST MISSOURI. SURFACE HIGH SAT OVER EASTERN NORTH DAKOTA. STRATUS ALONG THE SOUTH AND WEST SIDES OF THE HIGH PRESSURE HAS SLOWLY DISSIPATED THROUGH THE DAY. TEMPERATURES WERE IN THE UPPER 20S IN NORTHWEST ILLINOIS TO THE LOWER 40S IN WEST CENTRAL ILLINOIS. A CHANGE IN THE 500 HPA PATTERN WILL OCCUR OVER THE NEXT SEVEN DAYS AS WE GO FROM THE CURRENT NORTHWEST FLOW ALOFT TO A MORE ZONAL FLOW WHICH WILL CONTINUE INTO EARLY NEXT WEEK. THIS WILL RESULT IN SLOWLY MODERATING TEMPERATURES AS THE COLD AIR OF THE LAST WEEK RETREATS NORTHWARD. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 218 PM CST THU NOV 28 2013 MODELS ARE IN GOOD OVERALL AGREEMENT WITH THE NAM/RAP BEING AN OUTLIER WITH LOW LEVEL MOISTURE IN PLACE ACROSS THE REGION. THE MAIN FORECAST CONCERNS WILL BE THE POTENTIAL FOR CLOUD COVER OVERNIGHT INTO FRIDAY AS WELL AS TEMPERATURES ON FRIDAY. HIGH PRESSURE IS FORECAST TO BUILD SOUTHEASTWARD OVERNIGHT AND BE CENTERED ALONG THE IOWA AND ILLINOIS BORDER BY 12 UTC ON FRIDAY. AN EXTENSIVE STRATUS DECK DEVELOPED ON THE SOUTH AND WEST SIDES OF THE HIGH PRESSURE THIS MORNING WITH A STRONG INVERSION IN PLACE ACROSS THE UPPER MIDWEST AND NORTHERN PLAINS. THE 12 UTC SOUNDINGS AT KBIS AND KABR SHOWED EXTENSIVE LOW LEVEL MOISTURE IN PLACE. THE ECMWF...GFS... AND GEM CONTINUE TO SHOW A DRIER INVERSION IN PLACE ACROSS THE REGION OVERNIGHT WHILE THE NAM AND RAP SHOW MORE MOISTURE IN THE LOWER LEVELS OF THE ATMOSPHERE BUT NOT TO THE EXTENT THAT EXISTED AT KBIS AND KABR THIS MORNING. THEREFORE I AM NOT ANTICIPATING THE FORMATION OF NEW STRATUS TONIGHT SO GOING WITH CLEAR SKIES TONIGHT. A GOOD RADIATIONAL COOLING NIGHT AND EXPECT TEMPERATURES TO FALL QUICKLY THIS EVENING. HIGH PRESSURE IS FORECAST TO SHIFT EASTWARD DURING THE DAY ON FRIDAY WITH WINDS VEERING TO THE SOUTHEAST DURING THE AFTERNOON HOURS. 850 HPA TEMPERATURES WARM FROM -4 TO -10*C TODAY TO 0 TO -4*C ON FRIDAY. HAVE WARMED TEMPERATURES UP BY A COUPLE OF DEGREES BUT MID LEVEL CLOUDINESS WILL BE ON THE INCREASE TOMORROW AHEAD OF ANOTHER WAVE THAT WILL ARRIVE ON SATURDAY. THE INCREASING CLOUDS MAY HELP TO KEEP TEMPERATURES FROM WARMING AS THEY DID TODAY. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 218 PM CST THU NOV 28 2013 FRIDAY NIGHT...WEAK NORTHERN STREAM CLIPPER WILL CONTINUE MOVING TO GREAT LAKES BY SATURDAY MORNING. OVERNIGHT LOW TEMPERATURES WILL BE IN THE 20S. SATURDAY AND SUNDAY...TEMPERATURES WILL RANGE NEAR OR SLIGHTLY ABOVE NORMAL ON SATURDAY BEFORE A WEAK SURFACE TROF CROSSES THE AREA SWITCHING THE WIND TO THE WEST NORTHWEST LATE IN THE DAY. WITH LIMITED MOISTURE THIS TROF PASSAGE WILL BE DRY. ON SUNDAY...WEAK COLD AIR ADVECTION BEHIND THE TROF PASSAGE WILL PRODUCE LOW TEMPERATURES IN THE IN 20S ON SATURDAY NIGHT WITH HIGHS IN THE MID 30S ACROSS THE NORTHERN THIRD OF THE FORECAST AREA WITH HIGHS IN THE 40S OVER THE SOUTH. MONDAY THROUGH WEDNESDAY...LATEST MEDIUM RANGE MODEL SOLUTIONS CONTINUE TO DIVERGE BUT THERE IS OVERALL AGREEMENT IN DEVELOPING A DEEP TROF ACROSS THE WESTERN UNITED STATES BY MID WEEK. THE ENERGETIC SYSTEM CURRENTLY DIVING SOUTH ALONG THE WEST COAST WILL BEGIN A PERIOD OF ACTIVE WEATHER FOR THE MIDWEST. THE 12Z GFS KEEPS THE FORECAST AREA MAINLY DRY THROUGH TUESDAY. HOWEVER...THE 12Z ECMWF IS FASTER AND BRINGS PRECIPITATION INTO THE REGION ON MONDAY. IN EITHER CASE MOISTURE ADVECTION FROM THE GULF OF MEXICO AHEAD OF THE SURFACE LOW WILL BREAK OUT PRECIPITATION EITHER MONDAY OR TUESDAY. THE PRECIPITATION COULD FALL AS A MIXTURE OF RAIN AND SNOW. THURSDAY AND FRIDAY...CONFIDENCE IS LOW AS MODEL SOLUTIONS SHOW MAJOR DISCREPANCIES. THE 12Z RUN OF THE ECMWF PROGS A SURFACE LOW TO DEVELOP OVER THE CENTRAL ROCKIES AND TRACK NORTHWEST OF IOWA ON THURSDAY. IF THIS TRACK IS CORRECT WARM AIR ADVECTION AHEAD OF THIS LOW WOULD PRODUCE A RAIN OR RAIN/SNOW MIX TURNING TO ALL RAIN WITH A SNOW STORM OCCURRING OVER WESTERN IOWA AND THE NORTHERN PLAINS. ON THE OTHER HAND THE 12Z RUN OF THE GFS TRACKS THE SURFACE LOW FURTHER SOUTHEAST AND PROGS IT TO MOVE ACROSS MISSOURI INTO NORTHERN ILLINOIS/INDIANA BY FRIDAY. IF THE GFS SOLUTION IS CORRECT THERMAL PROFILES WOULD SUPPORT AN ALL SNOW EVENT LATE NEXT WEEK. HOWEVER I MUST STRONGLY REITERATE FORECAST CONFIDENCE IS LOW.&& .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1136 AM CST THU NOV 28 2013 A COOL FRONT HAS SHIFTED EASTWARD INTO ILLINOIS THIS MORNING WITH WINDS BECOMING WEST TO NORTHWEST BEHIND THE FRONT. EXPECT TAFS TO REMAIN VFR THROUGH THE PERIOD HOWEVER MONITORING STRATUS ACROSS THE DAKOTAS WHICH MAY MOVE INTO THE REGION AFTER 00 UTC ON FRIDAY. IN THE MEAN TIME A CEILING OF AROUND 4KFT WILL ROTATE THROUGH KDBQ AND KCID THIS AFTERNOON. IF THE STRATUS REMAINS IN PLACE A BKN CEILING OF AROUND 2500 WILL MOVE INTO ALL TAF SITES. OVERNIGHT. CONFIDENCE IS LOW THAT THIS WILL OCCUR. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...COUSINS SHORT TERM...COUSINS LONG TERM...KUHL AVIATION...COUSINS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1021 AM MST THU NOV 28 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 358 AM MST THU NOV 28 2013 FORECAST PROBLEM WILL BE TEMPERATURES. SATELLITE SHOWING AN AMPLIFIED PATTERN FROM THE PACIFIC INTO EASTERN NORTH AMERICA. SOUTHERN PORTION OF THE TROUGH ALONG THE WEST COAST HAS SPLIT AND CUT OFF FROM THE NORTHERN PORTION. THIS IS LEAVING A STRONG RIDGE OVER THE WESTERN PORTION OF THE COUNTRY WITH NORTHWEST FLOW ALOFT OVER THE AREA. DRY AIR MASS AT ALL LEVELS IS IN PLACE ACROSS THE REGION. MODELS DID FINE AT UPPER LEVELS. AT MID LEVELS...THE GFS WAS DOING THE BEST WITH THE UKMET NOT TOO FAR BEHIND IT. THE NAM WAS DOING A LITTLE BETTER THAN THE ECMWF ON THE SURFACE WIND AND PRESSURE FIELD. NAM AND ECMWF WERE DOING A LITTLE BETTER THAN THE GFS AND CANADIAN ON THE LOW LEVEL THERMAL FIELD. TODAY/TONIGHT...INTERESTING AND TRICKY TEMPERATURE FORECAST. SHALLOW COLD FRONT WAS BEGINNING TO PUSH THROUGH THE AREA AND SHOULD BE THROUGH MOST OF THE AREA BY 12Z TODAY. COLD AIR ADVECTION WILL CONTINUE THROUGH THE DAY AS SURFACE BECOME EASTERLY. SOME THIN HIGH LEVEL CLOUD COVER MAY COME IN DURING THE DAY AND CONTINUE INTO TONIGHT BUT DO NOT EXPECT IT TO BE HAMPER WARMING. WHAT MAY IMPACT HIGH TEMPERATURES TODAY IS LARGE AREA OF STRATUS MOVING SOUTH ACROSS NEBRASKA AT THIS TIME. THE RAP AND NAM TENDED TO CATCH THIS BUT WERE EITHER NOT FAR ENOUGH SOUTH OR WEST WITH THIS AREA. TAKING THOSE MODELS AT FACE VALUE WOULD SAY THAT STRATUS AND MAYBE SOME FOG WILL MOVE INTO THE NORTHEAST PORTION OF THE AREA THIS MORNING. THE RAP IS THE MOST AGGRESSIVE AND KEEPS THE COLDEST TEMPERATURES THERE. AFTER COLLABORATION...ALL I DID WAS INCREASE CLOUD COVER A LITTLE. HOWEVER WILL CONTINUE TO MONITOR TRENDS FOR AS LONG AS POSSIBLE AND MAKE ANY NEEDED ADJUSTMENTS. TENDED TO COOLER IN THE NORTHEAST AND WARMER IN THE WEST AND SOUTHWEST. FOR TONIGHT MORE THAN MODEL IS NOW CONSISTENT IN BRINGING STRATUS IN RETURN FLOW BY LATER THIS EVENING INTO THE OVERNIGHT HOURS. THE NAM IS THE MOST AGGRESSIVE BUT THE ECMWF...GFS AND SREF ARE NOT FAR BEHIND. WITH THIS NEW DATA AND COLLABORATION...KEPT THE FREEZING FOG AND INCREASED THE SKY COVER AFTER 06Z. DEPENDING ON HOW FAST THE STRATUS COMES IN...EASTERN LOCATIONS COULD DROP QUICKLY. FRIDAY/FRIDAY NIGHT...STRATUS LOOKS TO HANG ON THROUGH THE MORNING WHICH COULD IMPACT TEMPERATURES...ESPECIALLY IF IT HANGS ON LONGER. MODELS STILL WAFFLING BACK AND FORTH AS TO HOW FAR BACK EAST TO TAKE THE COLD AIR/COLD FRONT. EARLIER OUTPUT TENDED TO KEEP THE COLD AIR FARTHER WEST WHILE THE NEWER OUTPUT IS NOW FURTHER EAST. ONE THING FOR SURE...WILL DEFINITELY HAVE QUITE A GRADIENT IN TEMPERATURES WITH A HIGH DEGREE OF UNCERTAINTY/POTENTIAL TO BE VERY WRONG. SATURDAY/SATURDAY NIGHT...MODELS THEN START HAVING PROBLEMS IN RESOLVING THE MID AND UPPER LEVEL FLOW WITH LITTLE AGREEMENT SHOWN BY THE OUTPUT. WEST NORTHWEST TO NORTHWEST FLOW ALOFT WITH EMBEDDED SHORTWAVES COME THROUGH DURING THIS TIME. THE STRONGEST ONE MOVES ACROSS THE NORTH CENTRAL PORTION OF THE COUNTRY. THIS PUSHES ANOTHER COLD FRONT THROUGH FROM LATE IN THE MORNING INTO THE EARLY AFTERNOON. THE BRUNT OF THE COOLING LOOKS TO OCCUR OVER THE EASTERN THIRD TO HALF. SO ONCE AGAIN THERE COULD BE A BIG GRADIENT IN TEMPERATURES ACROSS THE AREA. CURRENT GRIDS HAD THIS LAYOUT CAPTURED WELL AND ONLY MADE SLIGHT ADJUSTMENTS. BUT THERE IS POTENTIAL THAT THESE TEMPERATURES WILL NEED TO BE ADJUSTED IF THE SPEED AND POSITION OF THIS FRONT CHANGES. THANKS TO ALL FOR THE COLLABORATION. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 358 AM MST THU NOV 28 2013 H5 ZONAL FLOW AND H3 CONFLUENCE WILL BE IN PLACE THROUGH THE EARLY PART OF THE WEEK...WHICH WILL SUPPORT LARGE SCALE STABLE/DRY CONDITIONS OVER MUCH OF THE PLAINS. SURFACE TO H85 W-SW FLOW ASSOCIATED WITH LEE TROUGH DEVELOPMENT ALONG THE KS/CO BORDER WILL SUPPORT WAA AND MILD TEMPERATURES ACROSS THE REGION. A WEAK COLD FRONT OVER THE NORTHERN PLAINS WILL LIFT NORTH AND EAST SUNDAY WITH HIGHS WARMING TO LOW TO MID 50S. CONTINUED MODERATION OF AIR MASS ON MONDAY SHOULD SUPPORT HIGHS AT LEAST IN THE MID 50S. ECMWF MOS CONTINUES TO SHOW HIGHS IN UPPER 50S/NEAR 60F AND BASED ON WARM EPISODES IN THE SHORT TERM THIS MIGHT BE REASONABLE. TUESDAY-WEDNESDAY NIGHT...LESS CONFIDENCE IN THESE PERIODS REGARDING FINER DETAILS OF TEMPS/PRECIP CHANCES...HOWEVER GUIDANCE CONTINUES TO ADVERTISE A LARGE SCALE SHIFT IN THE PATTERN ACROSS THE WESTERN US. A STRONG UPPER LOW ORIGINATING OVER ALASKA IS ADVERTISED TO DROP SOUTH ALONG AMPLIFIED PACIFIC RIDGE INTO THE PACIFIC NW BY MONDAY NIGHT PULLING WITH IT A STRONG ARCTIC AIR MASS FROM POLAR REGIONS INTO THE NORTHERN PLAINS. GEM IS THE FASTEST ON ARCTIC FRONT MOVING INTO OUR CWA TUESDAY EVENING...HOWEVER LAST FEW RUNS OF ECMWF/GFS/GEFS LEAN TOWARDS A SLOWER FRONTAL TIMING (POSSIBLY AS LATE AS WED NIGHT). THERE IS A LARGE AMOUNT OF SPREAD REGARDING THE EVOLUTION OF THE UPPER LOW IN THE WESTERN US...WHICH WILL IMPACT ONSET OF PRECIPITATION AND THE MAGNITUDE OF COLD AIR. YESTERDAYS 12Z RUN OF ECMWF WAS AN EXTREME (AND CONCERNING) OUTLIER WITH H85 TEMPS BY NEXT THU -20C OR COLDER OVER PARTS OF OUR CWA. LATEST RUN OF ECMWF AND GFS ARE A LITTLE MORE IN LINE...HOWEVER BOTH WOULD SUPPORT VERY COLD TEMPERATURES SETTLING IN BY AT LEAST THE LATER PART OF NEXT WEEK. CONSIDERING THE PATTERN SHOULD SUPPORT AT LEAST BREEZY CONDITIONS AND VERY COLD OVERNIGHT TEMPS WE MAY END UP SEEING THE NEED FOR A WIND CHILL ADVISORY (WC VALUES LESS/EQUAL TO -15F) OR WARNING IF THE EXTREME SPECTRUM OF GUIDANCE WERE TO VERIFY. I TEND TO LEAN TOWARD THE MODEL MEAN AT THIS POINT FOR TUE/WED CONSIDERING RUN-RUN DIFFERENCES WHICH SHOWS COLDER TEMPS AND BETTER PRECIP CHANCES DELAYED TOWARDS WED/WED NIGHT AND OUTSIDE OUR CURRENT VALID FORECAST PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1014 AM MST THU NOV 28 2013 AT KMCK...STRATUS DECK HAS BEEN STEADILY ADVANCING TOWARDS THE TERMINAL ALL MORNING AND A PERIOD OF LOWER CIGS IS EXPECTED ROUGHLY BETWEEN 19Z AND 22Z THIS AFTERNOON. SATELLITE TRENDS SHOW SOME EROSION ON THE LEADING EDGE...SO THERE IS STILL SOME UNCERTAINTY THAT THE STRATUS CAN BE MAINTAINED WITH SURFACE HEATING. TONIGHT...LOW CIGS WITH THE STRATUS WILL STILL BE A POSSIBILITY ALTHOUGH THE WINDS ARE LIGHT THEY WILL HAVE AN UPSLOPE COMPONENT. PATCHY FREEZING FOG MAY ALSO DEVELOP IN THE OVERNIGHT BUT CONFIDENCE IS LACKING TO MENTION ATTM. AT KGLD...VFR EXPECTED THROUGH THE AFTERNOON AND EARLY EVENING. HOWEVER AS THE NIGHT WEARS ON LIGHT UPSLOPE WINDS WILL CONTRIBUTE TO THE DEVELOPMENT OF STRATUS AND POSSIBLE LOW CIGS. PATCHY FREEZING FOG MAY ALSO DEVELOP IN THE OVERNIGHT BUT CONFIDENCE IS LACKING TO MENTION ATTM. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...BULLER LONG TERM...DJR AVIATION...024
AREA FORECAST DISCUSSION
NWS GOODLAND KS
446 AM MST THU NOV 28 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 358 AM MST THU NOV 28 2013 FORECAST PROBLEM WILL BE TEMPERATURES. SATELLITE SHOWING AN AMPLIFIED PATTERN FROM THE PACIFIC INTO EASTERN NORTH AMERICA. SOUTHERN PORTION OF THE TROUGH ALONG THE WEST COAST HAS SPLIT AND CUT OFF FROM THE NORTHERN PORTION. THIS IS LEAVING A STRONG RIDGE OVER THE WESTERN PORTION OF THE COUNTRY WITH NORTHWEST FLOW ALOFT OVER THE AREA. DRY AIR MASS AT ALL LEVELS IS IN PLACE ACROSS THE REGION. MODELS DID FINE AT UPPER LEVELS. AT MID LEVELS...THE GFS WAS DOING THE BEST WITH THE UKMET NOT TOO FAR BEHIND IT. THE NAM WAS DOING A LITTLE BETTER THAN THE ECMWF ON THE SURFACE WIND AND PRESSURE FIELD. NAM AND ECMWF WERE DOING A LITTLE BETTER THAN THE GFS AND CANADIAN ON THE LOW LEVEL THERMAL FIELD. TODAY/TONIGHT...INTERESTING AND TRICKY TEMPERATURE FORECAST. SHALLOW COLD FRONT WAS BEGINNING TO PUSH THROUGH THE AREA AND SHOULD BE THROUGH MOST OF THE AREA BY 12Z TODAY. COLD AIR ADVECTION WILL CONTINUE THROUGH THE DAY AS SURFACE BECOME EASTERLY. SOME THIN HIGH LEVEL CLOUD COVER MAY COME IN DURING THE DAY AND CONTINUE INTO TONIGHT BUT DO NOT EXPECT IT TO BE HAMPER WARMING. WHAT MAY IMPACT HIGH TEMPERATURES TODAY IS LARGE AREA OF STRATUS MOVING SOUTH ACROSS NEBRASKA AT THIS TIME. THE RAP AND NAM TENDED TO CATCH THIS BUT WERE EITHER NOT FAR ENOUGH SOUTH OR WEST WITH THIS AREA. TAKING THOSE MODELS AT FACE VALUE WOULD SAY THAT STRATUS AND MAYBE SOME FOG WILL MOVE INTO THE NORTHEAST PORTION OF THE AREA THIS MORNING. THE RAP IS THE MOST AGGRESSIVE AND KEEPS THE COLDEST TEMPERATURES THERE. AFTER COLLABORATION...ALL I DID WAS INCREASE CLOUD COVER A LITTLE. HOWEVER WILL CONTINUE TO MONITOR TRENDS FOR AS LONG AS POSSIBLE AND MAKE ANY NEEDED ADJUSTMENTS. TENDED TO COOLER IN THE NORTHEAST AND WARMER IN THE WEST AND SOUTHWEST. FOR TONIGHT MORE THAN MODEL IS NOW CONSISTENT IN BRINGING STRATUS IN RETURN FLOW BY LATER THIS EVENING INTO THE OVERNIGHT HOURS. THE NAM IS THE MOST AGGRESSIVE BUT THE ECMWF...GFS AND SREF ARE NOT FAR BEHIND. WITH THIS NEW DATA AND COLLABORATION...KEPT THE FREEZING FOG AND INCREASED THE SKY COVER AFTER 06Z. DEPENDING ON HOW FAST THE STRATUS COMES IN...EASTERN LOCATIONS COULD DROP QUICKLY. FRIDAY/FRIDAY NIGHT...STRATUS LOOKS TO HANG ON THROUGH THE MORNING WHICH COULD IMPACT TEMPERATURES...ESPECIALLY IF IT HANGS ON LONGER. MODELS STILL WAFFLING BACK AND FORTH AS TO HOW FAR BACK EAST TO TAKE THE COLD AIR/COLD FRONT. EARLIER OUTPUT TENDED TO KEEP THE COLD AIR FARTHER WEST WHILE THE NEWER OUTPUT IS NOW FURTHER EAST. ONE THING FOR SURE...WILL DEFINITELY HAVE QUITE A GRADIENT IN TEMPERATURES WITH A HIGH DEGREE OF UNCERTAINTY/POTENTIAL TO BE VERY WRONG. SATURDAY/SATURDAY NIGHT...MODELS THEN START HAVING PROBLEMS IN RESOLVING THE MID AND UPPER LEVEL FLOW WITH LITTLE AGREEMENT SHOWN BY THE OUTPUT. WEST NORTHWEST TO NORTHWEST FLOW ALOFT WITH EMBEDDED SHORTWAVES COME THROUGH DURING THIS TIME. THE STRONGEST ONE MOVES ACROSS THE NORTH CENTRAL PORTION OF THE COUNTRY. THIS PUSHES ANOTHER COLD FRONT THROUGH FROM LATE IN THE MORNING INTO THE EARLY AFTERNOON. THE BRUNT OF THE COOLING LOOKS TO OCCUR OVER THE EASTERN THIRD TO HALF. SO ONCE AGAIN THERE COULD BE A BIG GRADIENT IN TEMPERATURES ACROSS THE AREA. CURRENT GRIDS HAD THIS LAYOUT CAPTURED WELL AND ONLY MADE SLIGHT ADJUSTMENTS. BUT THERE IS POTENTIAL THAT THESE TEMPERATURES WILL NEED TO BE ADJUSTED IF THE SPEED AND POSITION OF THIS FRONT CHANGES. THANKS TO ALL FOR THE COLLABORATION. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 358 AM MST THU NOV 28 2013 H5 ZONAL FLOW AND H3 CONFLUENCE WILL BE IN PLACE THROUGH THE EARLY PART OF THE WEEK...WHICH WILL SUPPORT LARGE SCALE STABLE/DRY CONDITIONS OVER MUCH OF THE PLAINS. SURFACE TO H85 W-SW FLOW ASSOCIATED WITH LEE TROUGH DEVELOPMENT ALONG THE KS/CO BORDER WILL SUPPORT WAA AND MILD TEMPERATURES ACROSS THE REGION. A WEAK COLD FRONT OVER THE NORTHERN PLAINS WILL LIFT NORTH AND EAST SUNDAY WITH HIGHS WARMING TO LOW TO MID 50S. CONTINUED MODERATION OF AIR MASS ON MONDAY SHOULD SUPPORT HIGHS AT LEAST IN THE MID 50S. ECMWF MOS CONTINUES TO SHOW HIGHS IN UPPER 50S/NEAR 60F AND BASED ON WARM EPISODES IN THE SHORT TERM THIS MIGHT BE REASONABLE. TUESDAY-WEDNESDAY NIGHT...LESS CONFIDENCE IN THESE PERIODS REGARDING FINER DETAILS OF TEMPS/PRECIP CHANCES...HOWEVER GUIDANCE CONTINUES TO ADVERTISE A LARGE SCALE SHIFT IN THE PATTERN ACROSS THE WESTERN US. A STRONG UPPER LOW ORIGINATING OVER ALASKA IS ADVERTISED TO DROP SOUTH ALONG AMPLIFIED PACIFIC RIDGE INTO THE PACIFIC NW BY MONDAY NIGHT PULLING WITH IT A STRONG ARCTIC AIR MASS FROM POLAR REGIONS INTO THE NORTHERN PLAINS. GEM IS THE FASTEST ON ARCTIC FRONT MOVING INTO OUR CWA TUESDAY EVENING...HOWEVER LAST FEW RUNS OF ECMWF/GFS/GEFS LEAN TOWARDS A SLOWER FRONTAL TIMING (POSSIBLY AS LATE AS WED NIGHT). THERE IS A LARGE AMOUNT OF SPREAD REGARDING THE EVOLUTION OF THE UPPER LOW IN THE WESTERN US...WHICH WILL IMPACT ONSET OF PRECIPITATION AND THE MAGNITUDE OF COLD AIR. YESTERDAYS 12Z RUN OF ECMWF WAS AN EXTREME (AND CONCERNING) OUTLIER WITH H85 TEMPS BY NEXT THU -20C OR COLDER OVER PARTS OF OUR CWA. LATEST RUN OF ECWMF AND GFS ARE A LITTLE MORE IN LINE...HOWEVER BOTH WOULD SUPPORT VERY COLD TEMPERATURES SETTLING IN BY AT LEAST THE LATER PART OF NEXT WEEK. CONSIDERING THE PATTERN SHOULD SUPPORT AT LEAST BREEZY CONDITIONS AND VERY COLD OVERNIGHT TEMPS WE MAY END UP SEEING THE NEED FOR A WIND CHILL ADVISORY (WC VALUES LESS/EQUAL TO -15F) OR WARNING IF THE EXTREME SPECTRUM OF GUIDANCE WERE TO VERIFY. I TEND TO LEAN TOWARD THE MODEL MEAN AT THIS POINT FOR TUE/WED CONSIDERING RUN-RUN DIFFERENCES WHICH SHOWS COLDER TEMPS AND BETTER PRECIP CHANCES DELAYED TOWARDS WED/WED NIGHT AND OUTSIDE OUR CURRENT VALID FORECAST PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 441 AM MST THU NOV 28 2013 MAIN PROBLEMS TO DEAL WITH ARE STRATUS NEAR KMCK IN THE FIRST PART OF THE PERIOD AND STRATUS FOR BOTH SITES...ESPECIALLY AT KGLD...TOWARD THE END OF THE PERIOD. COLD FRONT HAS MOVED THROUGH BOTH SITES. A LARGE AREA OF STRATUS HAS BEEN MOVING SOUTH ACROSS NEBRASKA. THIS AREA IS STILL WELL TO THE NORTHEAST OF KMCK. AT THIS TIME IT LOOKS LIKE THE EDGE OF THIS STRATUS FIELD WILL COME CLOSE TO KMCK. SO FROM MID MORNING UNTIL EARLY AFTERNOON PUT IN A SCATTERED LOW DECK WITH A TEMPO GROUP COVERING THE POSSIBILITY OF A MVFR CEILING. LATER TONIGHT AS SOUTHERLY WINDS INCREASE ON THE WEST SIDE OF THE EXITING SURFACE HIGH...LOW LEVEL MOISTURE WILL BE DRAWN NORTHWARD. AT THIS TIME IT LOOK LIKE KGLD HAVE MVFR CEILINGS DEVELOP AFTER 06Z. IT LOOKS LIKE ANY CEILINGS WILL STAY TO THE WEST OF KMCK AT THIS TIME. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...BULLER LONG TERM...DJR AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
358 AM MST THU NOV 28 2013 .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 358 AM MST THU NOV 28 2013 FORECAST PROBLEM WILL BE TEMPERATURES. SATELLITE SHOWING AN AMPLIFIED PATTERN FROM THE PACIFIC INTO EASTERN NORTH AMERICA. SOUTHERN PORTION OF THE TROUGH ALONG THE WEST COAST HAS SPLIT AND CUT OFF FROM THE NORTHERN PORTION. THIS IS LEAVING A STRONG RIDGE OVER THE WESTERN PORTION OF THE COUNTRY WITH NORTHWEST FLOW ALOFT OVER THE AREA. DRY AIR MASS AT ALL LEVELS IS IN PLACE ACROSS THE REGION. MODELS DID FINE AT UPPER LEVELS. AT MID LEVELS...THE GFS WAS DOING THE BEST WITH THE UKMET NOT TOO FAR BEHIND IT. THE NAM WAS DOING A LITTLE BETTER THAN THE ECMWF ON THE SURFACE WIND AND PRESSURE FIELD. NAM AND ECMWF WERE DOING A LITTLE BETTER THAN THE GFS AND CANADIAN ON THE LOW LEVEL THERMAL FIELD. TODAY/TONIGHT...INTERESTING AND TRICKY TEMPERATURE FORECAST. SHALLOW COLD FRONT WAS BEGINNING TO PUSH THROUGH THE AREA AND SHOULD BE THROUGH MOST OF THE AREA BY 12Z TODAY. COLD AIR ADVECTION WILL CONTINUE THROUGH THE DAY AS SURFACE BECOME EASTERLY. SOME THIN HIGH LEVEL CLOUD COVER MAY COME IN DURING THE DAY AND CONTINUE INTO TONIGHT BUT DO NOT EXPECT IT TO BE HAMPER WARMING. WHAT MAY IMPACT HIGH TEMPERATURES TODAY IS LARGE AREA OF STRATUS MOVING SOUTH ACROSS NEBRASKA AT THIS TIME. THE RAP AND NAM TENDED TO CATCH THIS BUT WERE EITHER NOT FAR ENOUGH SOUTH OR WEST WITH THIS AREA. TAKING THOSE MODELS AT FACE VALUE WOULD SAY THAT STRATUS AND MAYBE SOME FOG WILL MOVE INTO THE NORTHEAST PORTION OF THE AREA THIS MORNING. THE RAP IS THE MOST AGGRESSIVE AND KEEPS THE COLDEST TEMPERATURES THERE. AFTER COLLABORATION...ALL I DID WAS INCREASE CLOUD COVER A LITTLE. HOWEVER WILL CONTINUE TO MONITOR TRENDS FOR AS LONG AS POSSIBLE AND MAKE ANY NEEDED ADJUSTMENTS. TENDED TO COOLER IN THE NORTHEAST AND WARMER IN THE WEST AND SOUTHWEST. FOR TONIGHT MORE THAN MODEL IS NOW CONSISTENT IN BRINGING STRATUS IN RETURN FLOW BY LATER THIS EVENING INTO THE OVERNIGHT HOURS. THE NAM IS THE MOST AGGRESSIVE BUT THE ECMWF...GFS AND SREF ARE NOT FAR BEHIND. WITH THIS NEW DATA AND COLLABORATION...KEPT THE FREEZING FOG AND INCREASED THE SKY COVER AFTER 06Z. DEPENDING ON HOW FAST THE STRATUS COMES IN...EASTERN LOCATIONS COULD DROP QUICKLY. FRIDAY/FRIDAY NIGHT...STRATUS LOOKS TO HANG ON THROUGH THE MORNING WHICH COULD IMPACT TEMPERATURES...ESPECIALLY IF IT HANGS ON LONGER. MODELS STILL WAFFLING BACK AND FORTH AS TO HOW FAR BACK EAST TO TAKE THE COLD AIR/COLD FRONT. EARLIER OUTPUT TENDED TO KEEP THE COLD AIR FARTHER WEST WHILE THE NEWER OUTPUT IS NOW FURTHER EAST. ONE THING FOR SURE...WILL DEFINITELY HAVE QUITE A GRADIENT IN TEMPERATURES WITH A HIGH DEGREE OF UNCERTAINTY/POTENTIAL TO BE VERY WRONG. SATURDAY/SATURDAY NIGHT...MODELS THEN START HAVING PROBLEMS IN RESOLVING THE MID AND UPPER LEVEL FLOW WITH LITTLE AGREEMENT SHOWN BY THE OUTPUT. WEST NORTHWEST TO NORTHWEST FLOW ALOFT WITH EMBEDDED SHORTWAVES COME THROUGH DURING THIS TIME. THE STRONGEST ONE MOVES ACROSS THE NORTH CENTRAL PORTION OF THE COUNTRY. THIS PUSHES ANOTHER COLD FRONT THROUGH FROM LATE IN THE MORNING INTO THE EARLY AFTERNOON. THE BRUNT OF THE COOLING LOOKS TO OCCUR OVER THE EASTERN THIRD TO HALF. SO ONCE AGAIN THERE COULD BE A BIG GRADIENT IN TEMPERATURES ACROSS THE AREA. CURRENT GRIDS HAD THIS LAYOUT CAPTURED WELL AND ONLY MADE SLIGHT ADJUSTMENTS. BUT THERE IS POTENTIAL THAT THESE TEMPERATURES WILL NEED TO BE ADJUSTED IF THE SPEED AND POSITION OF THIS FRONT CHANGES. THANKS TO ALL FOR THE COLLABORATION. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 358 AM MST THU NOV 28 2013 H5 ZONAL FLOW AND H3 CONFLUENCE WILL BE IN PLACE THROUGH THE EARLY PART OF THE WEEK...WHICH WILL SUPPORT LARGE SCALE STABLE/DRY CONDITIONS OVER MUCH OF THE PLAINS. SURFACE TO H85 W-SW FLOW ASSOCIATED WITH LEE TROUGH DEVELOPMENT ALONG THE KS/CO BORDER WILL SUPPORT WAA AND MILD TEMPERATURES ACROSS THE REGION. A WEAK COLD FRONT OVER THE NORTHERN PLAINS WILL LIFT NORTH AND EAST SUNDAY WITH HIGHS WARMING TO LOW TO MID 50S. CONTINUED MODERATION OF AIR MASS ON MONDAY SHOULD SUPPORT HIGHS AT LEAST IN THE MID 50S. ECMWF MOS CONTINUES TO SHOW HIGHS IN UPPER 50S/NEAR 60F AND BASED ON WARM EPISODES IN THE SHORT TERM THIS MIGHT BE REASONABLE. TUESDAY-WEDNESDAY NIGHT...LESS CONFIDENCE IN THESE PERIODS REGARDING FINER DETAILS OF TEMPS/PRECIP CHANCES...HOWEVER GUIDANCE CONTINUES TO ADVERTISE A LARGE SCALE SHIFT IN THE PATTERN ACROSS THE WESTERN US. A STRONG UPPER LOW ORIGINATING OVER ALASKA IS ADVERTISED TO DROP SOUTH ALONG AMPLIFIED PACIFIC RIDGE INTO THE PACIFIC NW BY MONDAY NIGHT PULLING WITH IT A STRONG ARCTIC AIR MASS FROM POLAR REGIONS INTO THE NORTHERN PLAINS. GEM IS THE FASTEST ON ARCTIC FRONT MOVING INTO OUR CWA TUESDAY EVENING...HOWEVER LAST FEW RUNS OF ECMWF/GFS/GEFS LEAN TOWARDS A SLOWER FRONTAL TIMING (POSSIBLY AS LATE AS WED NIGHT). THERE IS A LARGE AMOUNT OF SPREAD REGARDING THE EVOLUTION OF THE UPPER LOW IN THE WESTERN US...WHICH WILL IMPACT ONSET OF PRECIPITATION AND THE MAGNITUDE OF COLD AIR. YESTERDAYS 12Z RUN OF ECMWF WAS AN EXTREME (AND CONCERNING) OUTLIER WITH H85 TEMPS BY NEXT THU -20C OR COLDER OVER PARTS OF OUR CWA. LATEST RUN OF ECWMF AND GFS ARE A LITTLE MORE IN LINE...HOWEVER BOTH WOULD SUPPORT VERY COLD TEMPERATURES SETTLING IN BY AT LEAST THE LATER PART OF NEXT WEEK. CONSIDERING THE PATTERN SHOULD SUPPORT AT LEAST BREEZY CONDITIONS AND VERY COLD OVERNIGHT TEMPS WE MAY END UP SEEING THE NEED FOR A WIND CHILL ADVISORY (WC VALUES LESS/EQUAL TO -15F) OR WARNING IF THE EXTREME SPECTRUM OF GUIDANCE WERE TO VERIFY. I TEND TO LEAN TOWARD THE MODEL MEAN AT THIS POINT FOR TUE/WED CONSIDERING RUN-RUN DIFFERENCES WHICH SHOWS COLDER TEMPS AND BETTER PRECIP CHANCES DELAYED TOWARDS WED/WED NIGHT AND OUTSIDE OUR CURRENT VALID FORECAST PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1029 PM MST WED NOV 27 2013 VFR CONDITIONS WILL PREVAIL ACROSS THE CENTRAL HIGH PLAINS REGION AND THE MCK AND GLD TAF SITES THROUGH THE TAF PERIOD. LIGHT NORTHWEST TO WEST WINDS WILL TURN NORTHEASTERLY BY 19Z THURSDAY AS THE SURFACE HIGH PRESSURE AREA OVER THE NORTHERN PLAINS MOVES INTO THE CENTRAL PLAINS STATES. WINDS WILL REMAIN LIGHT AND TURN TO THE SOUTH AS THE HIGH MOVES OFF TO THE EAST AND A LEE TROUGH DEEPENS ALONG THE FRONT RANGE AFTER 00Z FRIDAY. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...BULLER LONG TERM...DJR AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1248 PM EST THU NOV 28 2013 LATEST UPDATE... AVIATION .SYNOPSIS... ISSUED AT 343 AM EST THU NOV 28 2013 A CLIPPER SYSTEM WILL BRING LAKE ENHANCED SNOWFALL TO THE REGION TODAY. TWO TO FIVE INCHES CAN BE EXPECTED BY THIS EVENING NORTH OF I-96...WHILE AREAS SOUTH OF I-96 WILL ONLY GET TWO INCHES OR LESS. THE SNOW IS EXPECTED TO GRADUALLY TAPER OFF TONIGHT. AFTER A QUIET FRIDAY AND FRIDAY NIGHT...ANOTHER COLD FRONT COMES IN FOR SATURDAY. THIS SYSTEM LOOKS TO BE WEAKER AND SHOULD ONLY GIVE THE REGION A DUSTING OF SNOW. THE WEEKEND AND INTO EARLY NEXT WEEK LOOKS QUIET...WITH THE NEXT CHANCE OF PRECIPITATION COMING IN ON WEDNESDAY. HIGH TEMPERATURES SHOULD MAINLY BE IN THE 30S. && .UPDATE... ISSUED AT 1150 PM EST THU NOV 28 2013 THE ADVISORIES HAVE BEEN UPDATED..MAIN EXPECTATION IS AREA OF LOCALIZED 3 TO 6 INCH SNOW POTENTIAL WITH NICE AREA OF SNOW THAT HAS DEVELOPED WEST AND NORTH OF GRAND RAPIDS AND INLAND FROM HOLLAND...MUSKEOGON...WHITEHALL. THE HRRR HAS THE BEST HANDLE ON THIS AREA ALTHOUGH IT DEVELOPED ABOUT 2 HOURS AHEAD OF WHAT THE HRRR WAS INDICATING EARLIER. THIS AREA WILL PERSIST THROUGH THE EARLY AFTNERNOON BEFORE GRADUALLY PIVOTING EAST AND SOUTH AND WEAKENING. SO GRAND RAPIDS MAY SEE ANOTHER PERIOD OF LIGHT SNOW LATE AFTERNOON INTO EARLY THIS EVENING...OTHERWISE THE EVENT IS ABOUT OVER. THE ENHANCED SNOW IS ASSOCIATED WITH AN AREA OF COVERGING LAKE MOISTURE INTO A WEAK TROUGH OF LOW PRESSURE EXTENDING ACROSS THE STATE. LOW LEVEL CLOUD TEMPERATURES ARE GREAT TODAY FOR BOTH THE EFFICIENT PRODUCTION OF PRECIPITATON AND HIGH SNOW TO LIQUID RATIOS...I.E. LARGE...DRY...AND FLUFFY SNOWFLAKES. BASED ON PAST SIMILAR SCENARIOS...WOULD NOT BE SURPRISED TO SEE VERY LOCAL ADDITIONAL SNOWFALL OF 6+ INCHES THIS AFTERNOON...BUT THE LIGHT NATURE OF THE SNOW WILL MITIGATE THE POTENTIAL IMPACTS. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 343 AM EST THU NOV 28 2013 WILL KEEP THE SAME COUNTIES IN THE HEADLINE...BUT NOW THAT WE A TRANSITIONING INTO A SYNOPTIC/LAKE EFFECT COMBO EVENT...WILL JUST CALL IT A WINTER WEATHER ADVISORY FOR ALL COUNTIES. SOLID SW FLOW ENHANCED EVENT EVOLVING EARLY THIS MORNING. THE N/S ORIENTED LAKE BAND FROM OVERNIGHT WAS BEING PUSHED INLAND AS THE FLOW WAS GOING WEST AND WILL CONTINUE TO BACK TO THE SW LATE THIS MORNING. DEEP MOISTURE SEEN WITHIN THE DGZ ALONG WITH A STRONG OMEGA FOR THE CLASSIC BULLS-EYE WHICH SHOULD RESULT IN LARGER FLAKES AND FAVORABLE ACCUMULATION RATES BY LATE MORNING/EARLY AFTERNOON. INCREASED SNOW TOTALS FOR PORTIONS OF THE NW CWA AS THIS AREA SHOULD SEE THE BEST SYNOPTIC/LE COMBO. FEEL WE WILL SEE A FEW 5-6 INCH REPORTS FROM THIS ONE. THE HIGHEST TOTALS SHOULD OCCUR WHERE OROGRAPHIC LIFT ALSO PITCHES IN...OVER NORTHERN NEWAYGO AND LAKE COUNTIES. AS THE WAVE PASSES EAST THE FLOW WILL PIVOT TO THE WNW TOWARD NIGHTFALL...THEN CONTINUE TO PIVOT TO THE NNW BY LATE EVENING. THIS WILL SPRAY MUCH OF THE WESTERN HALF WITH SNOWFALL THIS EVENING. THEN INVERSION HEIGHTS CRASH TOWARD MIDNIGHT WHEN THE SNOW WILL DIMINISH. ANOTHER NORTHERN STREAM SYSTEM MOVES IN FOR SATURDAY. THIS APPEARS TO BE A WEAKER SYSTEM THAT SHOULD ONLY PUT DOWN MINIMAL SNOWS...LESS THAN AN INCH...AND MAINLY NORTH OF I-96. H8 TEMPS WARM BY THEN...SO IT APPEARS THIS SYSTEM WILL NOT HAVE MUCH LAKE EFFECT POTENTIAL. .LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 343 AM EST THU NOV 28 2013 THE LONG TERM PERIOD WILL BE PREDOMINATELY DRY WITH TEMPERATURES CLOSE TO NORMAL. SFC HIGH PRESSURE TO OUR NORTH OVER ONTARIO WILL PROVIDE MICHIGAN WITH A DRY/COOL EASTERLY FLOW OF AIR AND A PREDOMINATELY FLAT/ZONAL FLOW ALOFT WILL RESULT IN A VERY LOW POTENTIAL FOR ANY SIGNIFICANT SYSTEMS. THE UPPER FLOW DOES BEGIN TO AMPLIFY FOR THE MIDDLE TO LATE PART OF NEXT WEEK WITH A LONG WAVE TROUGH DEVELOPING OVER THE WRN UNITED STATES. SO THE PATTERN SHOULD BECOME MORE ACTIVE FOR SW MI BY NEXT THURSDAY... BUT CURRENTLY IT LOOKS LIKE RAIN WOULD BE THE MAIN PRECIP TYPE. THE COLD FRONT WHICH PASSES THROUGH ON SATURDAY NIGHT BRINGS DOWN H8 AIR NEAR -10C. THIS SHOULD BE COLD ENOUGH TO GENERATE SOME LAKE EFFECT CLOUDINESS AND LIGHT SNOW SHOWERS OR FLURRIES. INITIALLY ON SUNDAY THE FLOW IS NORTHERLY WHICH SUPPORTS SOME LIGHT SNOW ACROSS PORTIONS OF MASON AND OCEANA COUNTIES. THEN FOR SUNDAY NIGHT THROUGH TUESDAY THE LOW LEVEL FLOW IS MORE EASTERLY WHICH MEANS MOST OF THE AREA WILL BE DRY ALTHOUGH SOME FLURRIES FROM LAKE HURON MAY MAKE IT INLAND TOWARD THE CLARE AREA. THE DRY LOW LEVEL EAST FLOW AND SURFACE RIDGING MAY DELAY/FEND OFF INCOMING WAA PRECIP NEXT WEDNESDAY BUT MAY ALSO RESULT IN A WINTRY MIX AT THE PRECIP ONSET WED NIGHT DUE TO EVAPORATIVE COOLING/WET BULB EFFECTS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1239 PM EST THU NOV 28 2013 LIGHT SNOW WILL DIMINISH THIS EVENING. CIGS SHOULD REMAIN MOSTLY VFR EXCEPT AT KMKG THIS AFTERNOON. && .MARINE... ISSUED AT 343 AM EST THU NOV 28 2013 EXTENDED THE SCA THROUGH TODAY AS THE SW FLOW REMAIN BRISK. AFTER A CALMER PERIOD FOR TONIGHT AND FRIDAY...WE MAY NEED ANOTHER SCA BY FRIDAY NIGHT AS SSW WINDS INCREASE. && .HYDROLOGY... ISSUED AT 343 AM EST THU NOV 28 2013 PCPN WILL BE ALL SNOW THROUGH THE SHORT TERM WITH MINIMAL MELTING... SO NO HYDRO IMPACTS ARE EXPECTED. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ037>040-043>046-050-051-056-057-064. FLOOD WATCH THROUGH SATURDAY EVENING FOR MIZ045. LM...NONE. && $$ UPDATE...COBB SYNOPSIS...JK SHORT TERM...JK LONG TERM...MEADE AVIATION...93 HYDROLOGY...JK MARINE...JK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1238 PM EST THU NOV 28 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 520 AM EST THU NOV 28 2013 LARGE SCALE FIRST...THEN LETS TALK ABOUT MESOSCALE AND LK EFFECT ISSUES THAT ARE PLENTY. SHORTWAVE AND LOW PRESSURE TROUGH IN COOL NW FLOW CLOSING IN ON WESTERN UPR MICHIGAN. BATCH OF LGT SNOW EXTENDS FROM FAR WEST CWA TO THE NORTHWEST ALONG MN/ONTARIO BORDER. SO WIDESPREAD LGT SNOW WILL IMPACT THOSE TRAVELING THIS THANKSGIVING MORNING...ESPECIALLY OVER WESTERN CWA AND TOWARD WISCONSIN BORDER WHERE BETTER FORCING WITH THE SHORTWAVE RESIDES. OMEGA IN THE H7-H6 LAYER EXITS AFT 15Z...LEAVING MOSTLY NEGATIVE LARGE SCALE FORCING THROUGH TONIGHT. NOW ONTO THE MESOSCALE AND LAKE EFFECT ISSUES. IT IS NEVER A GOOD THING WHEN A LARGER SCALE TROUGH MERGES INTO AN UNSTABLE AND LIGHT WIND LAKE EFFECT ENVIRONMENT. CRAZY THINGS CAN HAPPEN. TODAY MAY END UP BEING ONE OF THESE DAYS. ONLY TIME WILL TELL. LK EFFECT IS ALREADY ONGOING. FIRST FOR LK SUPERIOR...STRONG MESOLOW CIRCULATION IS TAKING OFF JUST OFFSHORE OF MUNSING AND MAY ACTUALLY BE CLIPPING GRAND ISLAND. THIS IS LIKELY THE BEGINNING OF EVENTUAL HEAVY SNOW BAND TO IMPACT FAR NORTHERN KEWEENAW PENINSULA...VCNTY OF DELAWARE AND COPPER HARBOR...THOUGH MIDDAY. WINDS OVER LK SUPERIOR ARE MAINLY NE AT THIS TIME...BUT TOWARD THE SOUTH SHORE ARE BECOMING VARIABLE OR EVEN SOUTH THANKS TO APPROACHING LOW PRESSURE TROUGH AND LAND BREEZES /ACTUALLY SAW TEMPS DIP BLO ZERO OVR PARTS OF INTERIOR EASTERN UPR MICHIGAN THIS MORNING SHOWING THE CHILL OF THE AIRMASS/. AS THE MORNING WEARS ON...INCREASING SOUTH WINDS WILL CONVERGE WITH ENE WINDS OVR LK SUPERIOR RESULTING IN DOMINANT BAND OF SNOW OVR TIP OF KEWEENAW. ALREADY SEEING ECHOES ON MQT RADAR NEAR COPPER HARBOR BUT NOTHING YET PER THE KEWEENAW CO SHERIFF IN EAGLE RIVER. 00Z NAM SEEMED TOO QUICK IN SWINGING DOMINANT BAND BACK TO SOUTH THIS AFTN. 06Z NAM ADJUSTED AND NOW LOOKS LIKE PREFERRED 00Z GEM-REGIONAL AND LOCAL WRF-ARW AND RUC13. UPSHOT IS HEAVIER SNOW HANGS OUT ON TIP OF KEWEENAW THROUGH MIDDAY THEN SINKS SOUTH WITH MORE BRIEF HEAVIER SNOW SOUTH OF CALUMET BY MID-LATE AFTN. OVERALL THE GOING LK EFFECT SNOW ADVY LOOKS GOOD...THOUGH ISOLD AMOUNTS UP TO 10 INCHES NOT OUT QUESTION IF BAND STAYS IN SAME LOCATION. NOT ALL ABOUT LK SUPERIOR THOUGH AS LK MICHIGAN COULD BE INTERESTING AS WELL. SOUTH WINDS FORMING ON LK MICHIGAN ARE LEADING TO CONCERNS THAT LK EFFECT...POSSIBLY HEAVY...COULD IMPACT PARTS OF DELTA AND SOUTHERN SCHOOLCRAFT INTO THIS AFTN. GRB/APX RADAR ALREADY SHOWING SIGNS OF LK EFFECT MESO FEATURES ALONG DOOR PENINSULA AND ALONG NW SHORE OF NORTHERN LOWER MICHIGAN. RUC13 SFC CONVERGENCE FIELD DOING VERY NICE JOB OF PEGGING THESE AREAS AND IT SHOWS THEM MERGING OVER FAR NORTHERN LK MICHIGAN AFT 15Z AND AFFECTING MAINLY GARDEN PENINSULA ACROSS SOUTHERN SCHOOLCRAFT ZONE THIS AFTN. WAS VERY CLOSE TO GO WITH ADVY...BUT CONFIDENCE WAS NOT THERE AS THESE IS UNCERTAINTY IN HOW FAR NORTH THESE CIRCULATIONS WILL GET. RUC FCST IS VERIFYING WELL THOUGH AND DOES GET A LOT OF MERIT. SO...WILL PASS THIS ON TO DAYSHIFT AND LET THEM SEE HOW THINGS LOOK AFT DAYBREAK. PUT OUT A STRONGLY WORDED SPS AND MENTIONED THAT EITHER ADVY/WARNING COULD BE NEEDED LATER TODAY. ANYTHING IS POSSIBLE IN THIS KIND OF SETUP. TONIGHT WILL BASICALLY BE AN EXTENSION OF HOW LK EFFECT DEVELOPS TODAY...SO IT IS STILL KIND OF UNCERTAIN. LEANED ON NCEP HIGH RES WRF-ARW AND NMM RUNS AS WELL AS NAM WHICH COMES BACK INTO LINE WITH GOING THINKING. GENERALLY...SFC TROUGH SHOULD MOVE TO EASTERN LK SUPERIOR ALLOWING WINDS TO BECOME MORE NW OR WEST OVR MUCH OF UPR MICHIGAN. FIRST IMPACT WILL BE TO SHUNT LK EFFECT OFF LK MICHIGAN BACK TO THE SOUTH. HAVE CHANCES VERY EARLY IN THE EVENING...THEN DROP THEM TO SLIGHTS BY LATE EVENING. FARTHER NORTH...LK EFFECT SNOW SHOWERS WILL BE AFFECTING NORTHWEST CWA LATE AFTN/EARLY EVENING AND SHOULD SINK TOWARD NCNTRL UPR MICHIGAN...BIG BAY/MARQUETTE THROUGH THE EVENING AND OVERNIGHT HOURS AND EVENTUALLY MAKE IT ONSHORE TO EAST OF MARQUETTE TOWARD MUNISING AND GRAND MARAIS LATER TONIGHT. MODERATE ACCUMS COULD OCCUR TONIGHT FOR HIGHER TERRAIN OF WEST...VCNTY OF PORCUPINE MTS AND SETUP SEEMS GOOD FOR CONVERGENT BAND OF SNOW TO AFFECT GOOD PART OF BARAGA COUNTY...MAYBE EVEN RIGHT ALONG LK SHORE AT BARAGA/L`ANSE AS WELL. FOR NOW HAVE 2-4 INCHES IN THERE FOR THESE AREAS THIS EVENING. LOCALLY HEAVY SNOW MAY SPREAD TO BIG BAY/MARQUETTE LATER TONIGHT AS CONVERGENCE MAXIMIZES BTWN NW WINDS OVER LK SUPERIOR AND POSSIBLE LAND BREEZE OVER CNTRL UPR MICHIGAN. INLAND FM ALL THE LK EFFECT AND CLOUDS...SOME CLEARING AND LIGHTER WINDS MAY ALLOW TEMPS TO FALL INTO THE SINGLE DIGITS TOWARD WI BORDER AND OVER INTERIOR EASTERN CWA. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 505 AM EST THU NOV 28 2013 FRIDAY...A SPRAWLING SFC HIGH FROM NRN ONTARIO INTO THE OHIO VALLEY WILL RESULT IN A VERY WEAK GRADIENT ACROSS THE NRN GREAT LAKES. THE HIGH RES MODELS SUGGEST THAT THE CIRCULATION AROUND A LAKE INDUCED LOW OR TROUGH OVER SE LAKE SUPERIOR COULD FOCUS LES BANDS ANYWHERE FROM MARQUETTE TO MUNISING. IF THE LOW LEVEL CONVERGENCE IS STRONG ENOUGH THERE MAY BE A PERIOD OF HEAVY SNOW. HOWEVER...CONFIDENCE IN THE LOCATION AND DURATION OF SUCH A BAND IS LOW. SO...FCST SNOWFALL AMOUNTS WERE LIMITED TO AROUND AN INCH. DEVELOPING SRLY FLOW IN THE AFTERNOON WILL PUSH THE REMAINING LES OFFSHORE. ANY SNOWBANDS MOVING INTO THE WEST SHOULD ALSO WEAKEN AND POSSIBLY LINGER ALONG THE SHORELINE UNTIL AFTERNOON WHEN OFF SHORE WINDS STRENGTHEN. 850 MB WAA WILL INCREASE IN THE AFTERNOON AS WEAK MID LEVEL RIDGING MOVES BACK OVER THE AREA AND A SFC HIGH BUILDS INTO THE ERN LAKES. HIGH TEMPS ARE EXPECTED TO REBOUND INTO THE MID AND UPPER 20S. FRI NIGHT AND SAT...THE MODELS WERE IN GOOD AGREEMENT WITH THE NEXT CLIPPER SHORTWAVE TROUGH SLIDING ACROSS NRN LAKE SUPERIOR LATE IN THE DAY ON SATURDAY. LIGHT SNOW DEVELOPING OVER SCNTRL CANADA IN THE WAA PATTERN AHEAD OF THE SHORTWAVE WILL SPREAD SNOW ACROSS NRN LAKE SUPERIOR FRI NIGHT PERHAPS BRUSHING THE NRN AND ERN COUNTIES WITH SOME LIGHT SNOW LATE FRI NIGHT INTO SAT. THE STRONGER FORCING AND BETTER SNOW POTENTIAL IS EXPECTED TO REMAIN NORTH OF LAKE SUPERIOR. HOWEVER...THERE MAY ALSO BE A PERIOD OF LAKE ENAHCNED SNOW INTO THE ERN CWA FROM LATE FRI NIGHT INTO SAT WITH SSW LOW LEVEL FLOW OFF OF LAKE MI VEERING TO THE SW. THE LONG FETCH WILL BE FAVORABLE BUT INSTABILITY WILL BE LIMITED WITH RELATIVELY DRY AIR OVER THE AREA BEFORE THE SHRTWV ARRIVES AND WAA PUSHING 850 MB TEMPS -8C TO -5C. SAT NIGHT...SOME LIGHT LAKE EFFECT SNOW SHOWERS ARE POSSIBLE IN THE WAKE OF THE SFC TROUGH AS WINDS VEER FROM NW TO N AND 850 MB TEMPS DROP FROM -10C TO -12C. WITH ONLY MARGINAL INSTABILITY...ONLY CHANCE POPS WERE INCLUDED. SUN INTO MON...AS HIGH PRES BUILDS INTO NRN ONTARIO WINDS WILL CONTINUE TO VEER FROM NNE TO E. 850 MB TEMPS AROUND -12C WILL PROVIDE JUST ENOUGH INSTABILITY TO KEEP LES CHANCES GOING ACROSS NORTH CENTRAL UPPER MICHIGAN AND THE KEWEENAW. NEAR NORMAL TEMPS ARE EXPECTED WITH HIGHS AROUND 30 TO THE LOWER 30S AND LOWS IN THE LOWER 20S. TUE AND WED...MODELS DIFFER WITH THE APPROACH OF THE NEXT SHORTWAVE EMERGING FROM THE WRN CONUS TROF. THE GFS INDICATES A MORE POSITIVE-TILT WRN CONUS TROF AND LESS AMPLIFICATION OF RIDGE DOWNSTREAM ALLOWING FOR A QUICKER ADVANCE OF A SHORTWAVE AND ASSOCIATED FRONTAL SYSTEM INTO THE WRN LAKES. THE ECMWF INDICATES A MORE AMPLIFIED PATTERN ACROSS THE CONUS WITH A SLOWER ADVANCE OF THE SHORTWAVE MOVING TOWARD THE WRN LAKES. THE FCST CONTINUED TO USE A MDLS CONSENSUS THAT REFLECTS A SLIGHTLY LATER ARRIVAL OF PCPN CHANCES FROM TUE NIGHT INTO WED. THE MODELS ALSO TRENDED TOWARD A LESS AMPLIFIED SOLUTION WITH COLDER AIR ACROSS THE NRN LAKES WHICH WOULD REDUCE THE CHANCE FOR ANY RAIN. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1237 PM EST THU NOV 28 2013 FORECAST WILL BE A CHALLENGE OVER THE NEXT 24HRS. MULTIPLE MESO-LOWS OVER LAKE SUPERIOR THAT ARE NOT HANDLED WELL BY ANY MODELS SHOULD MOVE ONSHORE TODAY INTO TONIGHT...MAKING ALL TAF ELEMENTS VERY DIFFICULT TO FORECAST MORE THAN A COUPLE HOURS OUT. PUT BEST GUESS INTO TAFS...BUT MULTIPLE AMENDMENTS MAY BE NEEDED AS VERY SMALL SCALE FEATURES MOVE OVER TAF SITES. SEEMS CMX HAS THE BEST CHANCE OF SEEING LOWERED CONDITIONS AS A HEAVY LAKE EFFECT SNOW BAND OVER THE NORTHERN KEWEENAW MOVES SOUTH. IWD HAS THE NEXT BEST CHANCE OF LOWERING CONDITIONS AS A STRONG MESO-LOW OVER WESTERN LAKE SUPERIOR MOVES ONSHORE IN NW WI OR WRN UPPER MI. SAW HAS THE LOWEST CHANCES OF SEEING DECREASED CONDITIONS...BUT THERE IS STILL A CHANCE THAT A MESO-LOW OVER SOUTH CENTRAL LAKE SUPERIOR WILL MOVE ONSHORE NEAR MARQUETTE THAT WOULD IMPACT THAT SITE AS WELL. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 343 PM EST WED NOV 27 2013 STRONGER N WINDS WILL CONTINUE TO SLOWLY DIMINISH THIS EVENING. A RIDGE OF HIGH PRESSURE WILL EXTEND OVER LAKE SUPERIOR THIS EVENING...WHILE A WEAK LOW OVER THE EASTERN DAKOTAS PUSHES ACROSS THE UPPER GREAT LAKES LATE TONIGHT THROUGH THURSDAY. LARGER HIGH PRESSURE EXTENDING ACROSS MUCH OF CENTRAL CANADA THROUGH THE CENTRAL PLAINS THURSDAY AFTERNOON WILL SWING ACROSS THE UPPER GREAT LAKES THURSDAY NIGHT...BEFORE EXITING TO THE LOWER GREAT LAKES AND NEW ENGLAND STATES FRIDAY AFTERNOON THROUGH SATURDAY. EXPECT A LOW OVER LAKE WINNIPEG FRIDAY NIGHT TO PUSH ACROSS SOUTHERN ONTARIO AND LAKE SUPERIOR SATURDAY AND SATURDAY EVENING. THERE IS THE POTENTIAL FOR 30KT S GUSTS DURING THE DAY SATURDAY. FOR SUNDAY AND MONDAY...HIGH PRESSURE SCOOTING ACROSS ONTARIO WILL PUSH A RIDGE OVER LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ001. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...JLB AVIATION...TITUS MARINE...KF
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1154 AM EST THU NOV 28 2013 LATEST UPDATE...MORNING UPDATE .SYNOPSIS... ISSUED AT 343 AM EST THU NOV 28 2013 A CLIPPER SYSTEM WILL BRING LAKE ENHANCED SNOWFALL TO THE REGION TODAY. TWO TO FIVE INCHES CAN BE EXPECTED BY THIS EVENING NORTH OF I-96...WHILE AREAS SOUTH OF I-96 WILL ONLY GET TWO INCHES OR LESS. THE SNOW IS EXPECTED TO GRADUALLY TAPER OFF TONIGHT. AFTER A QUIET FRIDAY AND FRIDAY NIGHT...ANOTHER COLD FRONT COMES IN FOR SATURDAY. THIS SYSTEM LOOKS TO BE WEAKER AND SHOULD ONLY GIVE THE REGION A DUSTING OF SNOW. THE WEEKEND AND INTO EARLY NEXT WEEK LOOKS QUIET...WITH THE NEXT CHANCE OF PRECIPITATION COMING IN ON WEDNESDAY. HIGH TEMPERATURES SHOULD MAINLY BE IN THE 30S. && .UPDATE... ISSUED AT 1150 PM EST THU NOV 28 2013 THE ADVISORIES HAVE BEEN UPDATED..MAIN EXPECTATION IS AREA OF LOCALIZED 3 TO 6 INCH SNOW POTENTIAL WITH NICE AREA OF SNOW THAT HAS DEVELOPED WEST AND NORTH OF GRAND RAPIDS AND INLAND FROM HOLLAND...MUSKEOGON...WHITEHALL. THE HRRR HAS THE BEST HANDLE ON THIS AREA ALTHOUGH IT DEVELOPED ABOUT 2 HOURS AHEAD OF WHAT THE HRRR WAS INDICATING EARLIER. THIS AREA WILL PERSIST THROUGH THE EARLY AFTNERNOON BEFORE GRADUALLY PIVOTING EAST AND SOUTH AND WEAKENING. SO GRAND RAPIDS MAY SEE ANOTHER PERIOD OF LIGHT SNOW LATE AFTERNOON INTO EARLY THIS EVENING...OTHERWISE THE EVENT IS ABOUT OVER. THE ENHANCED SNOW IS ASSOCIATED WITH AN AREA OF COVERGING LAKE MOISTURE INTO A WEAK TROUGH OF LOW PRESSURE EXTENDING ACROSS THE STATE. LOW LEVEL CLOUD TEMPERATURES ARE GREAT TODAY FOR BOTH THE EFFICIENT PRODUCTION OF PRECIPITATON AND HIGH SNOW TO LIQUID RATIOS...I.E. LARGE...DRY...AND FLUFFY SNOWFLAKES. BASED ON PAST SIMILAR SCENARIOS...WOULD NOT BE SURPRISED TO SEE VERY LOCAL ADDITIONAL SNOWFALL OF 6+ INCHES THIS AFTERNOON...BUT THE LIGHT NATURE OF THE SNOW WILL MITIGATE THE POTENTIAL IMPACTS. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 343 AM EST THU NOV 28 2013 WILL KEEP THE SAME COUNTIES IN THE HEADLINE...BUT NOW THAT WE A TRANSITIONING INTO A SYNOPTIC/LAKE EFFECT COMBO EVENT...WILL JUST CALL IT A WINTER WEATHER ADVISORY FOR ALL COUNTIES. SOLID SW FLOW ENHANCED EVENT EVOLVING EARLY THIS MORNING. THE N/S ORIENTED LAKE BAND FROM OVERNIGHT WAS BEING PUSHED INLAND AS THE FLOW WAS GOING WEST AND WILL CONTINUE TO BACK TO THE SW LATE THIS MORNING. DEEP MOISTURE SEEN WITHIN THE DGZ ALONG WITH A STRONG OMEGA FOR THE CLASSIC BULLS-EYE WHICH SHOULD RESULT IN LARGER FLAKES AND FAVORABLE ACCUMULATION RATES BY LATE MORNING/EARLY AFTERNOON. INCREASED SNOW TOTALS FOR PORTIONS OF THE NW CWA AS THIS AREA SHOULD SEE THE BEST SYNOPTIC/LE COMBO. FEEL WE WILL SEE A FEW 5-6 INCH REPORTS FROM THIS ONE. THE HIGHEST TOTALS SHOULD OCCUR WHERE OROGRAPHIC LIFT ALSO PITCHES IN...OVER NORTHERN NEWAYGO AND LAKE COUNTIES. AS THE WAVE PASSES EAST THE FLOW WILL PIVOT TO THE WNW TOWARD NIGHTFALL...THEN CONTINUE TO PIVOT TO THE NNW BY LATE EVENING. THIS WILL SPRAY MUCH OF THE WESTERN HALF WITH SNOWFALL THIS EVENING. THEN INVERSION HEIGHTS CRASH TOWARD MIDNIGHT WHEN THE SNOW WILL DIMINISH. ANOTHER NORTHERN STREAM SYSTEM MOVES IN FOR SATURDAY. THIS APPEARS TO BE A WEAKER SYSTEM THAT SHOULD ONLY PUT DOWN MINIMAL SNOWS...LESS THAN AN INCH...AND MAINLY NORTH OF I-96. H8 TEMPS WARM BY THEN...SO IT APPEARS THIS SYSTEM WILL NOT HAVE MUCH LAKE EFFECT POTENTIAL. .LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 343 AM EST THU NOV 28 2013 THE LONG TERM PERIOD WILL BE PREDOMINATELY DRY WITH TEMPERATURES CLOSE TO NORMAL. SFC HIGH PRESSURE TO OUR NORTH OVER ONTARIO WILL PROVIDE MICHIGAN WITH A DRY/COOL EASTERLY FLOW OF AIR AND A PREDOMINATELY FLAT/ZONAL FLOW ALOFT WILL RESULT IN A VERY LOW POTENTIAL FOR ANY SIGNIFICANT SYSTEMS. THE UPPER FLOW DOES BEGIN TO AMPLIFY FOR THE MIDDLE TO LATE PART OF NEXT WEEK WITH A LONG WAVE TROUGH DEVELOPING OVER THE WRN UNITED STATES. SO THE PATTERN SHOULD BECOME MORE ACTIVE FOR SW MI BY NEXT THURSDAY... BUT CURRENTLY IT LOOKS LIKE RAIN WOULD BE THE MAIN PRECIP TYPE. THE COLD FRONT WHICH PASSES THROUGH ON SATURDAY NIGHT BRINGS DOWN H8 AIR NEAR -10C. THIS SHOULD BE COLD ENOUGH TO GENERATE SOME LAKE EFFECT CLOUDINESS AND LIGHT SNOW SHOWERS OR FLURRIES. INITIALLY ON SUNDAY THE FLOW IS NORTHERLY WHICH SUPPORTS SOME LIGHT SNOW ACROSS PORTIONS OF MASON AND OCEANA COUNTIES. THEN FOR SUNDAY NIGHT THROUGH TUESDAY THE LOW LEVEL FLOW IS MORE EASTERLY WHICH MEANS MOST OF THE AREA WILL BE DRY ALTHOUGH SOME FLURRIES FROM LAKE HURON MAY MAKE IT INLAND TOWARD THE CLARE AREA. THE DRY LOW LEVEL EAST FLOW AND SURFACE RIDGING MAY DELAY/FEND OFF INCOMING WAA PRECIP NEXT WEDNESDAY BUT MAY ALSO RESULT IN A WINTRY MIX AT THE PRECIP ONSET WED NIGHT DUE TO EVAPORATIVE COOLING/WET BULB EFFECTS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 657 AM EST THU NOV 28 2013 IFR VSBYS IN SNOW ARE LIKELY AT MKG/GRR/LAN THROUGH MID MORNING WITH MVFR TYPE VSBYS EXPECTED THEREAFTER. CONDITIONS SHOULD IMPROVE TO VFR TONIGHT AS THE SNOW ENDS. BASED ON WHERE THE SRN EDGE OF THE SNOW IS SETTING UP... THERE IS A HIGH PROBABILITY OF VFR CONDITIONS WITH NO SNOW TODAY ALONG THE I-94 CORRIDOR REGION INCLUDING AZO/BTL/JXN. && .MARINE... ISSUED AT 343 AM EST THU NOV 28 2013 EXTENDED THE SCA THROUGH TODAY AS THE SW FLOW REMAIN BRISK. AFTER A CALMER PERIOD FOR TONIGHT AND FRIDAY...WE MAY NEED ANOTHER SCA BY FRIDAY NIGHT AS SSW WINDS INCREASE. && .HYDROLOGY... ISSUED AT 343 AM EST THU NOV 28 2013 PCPN WILL BE ALL SNOW THROUGH THE SHORT TERM WITH MINIMAL MELTING... SO NO HYDRO IMPACTS ARE EXPECTED. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ037>040-043>046-050-051-056-057-064. FLOOD WATCH THROUGH SATURDAY EVENING FOR MIZ045. LM...NONE. && $$ UPDATE...COBB SYNOPSIS...JK SHORT TERM...JK LONG TERM...MEADE AVIATION...MEADE HYDROLOGY...JK MARINE...JK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
650 AM EST THU NOV 28 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 520 AM EST THU NOV 28 2013 LARGE SCALE FIRST...THEN LETS TALK ABOUT MESOSCALE AND LK EFFECT ISSUES THAT ARE PLENTY. SHORTWAVE AND LOW PRESSURE TROUGH IN COOL NW FLOW CLOSING IN ON WESTERN UPR MICHIGAN. BATCH OF LGT SNOW EXTENDS FROM FAR WEST CWA TO THE NORTHWEST ALONG MN/ONTARIO BORDER. SO WIDESPREAD LGT SNOW WILL IMPACT THOSE TRAVELING THIS THANKSGIVING MORNING...ESPECIALLY OVER WESTERN CWA AND TOWARD WISCONSIN BORDER WHERE BETTER FORCING WITH THE SHORTWAVE RESIDES. OMEGA IN THE H7-H6 LAYER EXITS AFT 15Z...LEAVING MOSTLY NEGATIVE LARGE SCALE FORCING THROUGH TONIGHT. NOW ONTO THE MESOSCALE AND LAKE EFFECT ISSUES. IT IS NEVER A GOOD THING WHEN A LARGER SCALE TROUGH MERGES INTO AN UNSTABLE AND LIGHT WIND LAKE EFFECT ENVIRONMENT. CRAZY THINGS CAN HAPPEN. TODAY MAY END UP BEING ONE OF THESE DAYS. ONLY TIME WILL TELL. LK EFFECT IS ALREADY ONGOING. FIRST FOR LK SUPERIOR...STRONG MESOLOW CIRCULATION IS TAKING OFF JUST OFFSHORE OF MUNSING AND MAY ACTUALLY BE CLIPPING GRAND ISLAND. THIS IS LIKELY THE BEGINNING OF EVENTUAL HEAVY SNOW BAND TO IMPACT FAR NORTHERN KEWEENAW PENINSULA...VCNTY OF DELAWARE AND COPPER HARBOR...THOUGH MIDDAY. WINDS OVER LK SUPERIOR ARE MAINLY NE AT THIS TIME...BUT TOWARD THE SOUTH SHORE ARE BECOMING VARIABLE OR EVEN SOUTH THANKS TO APPROACHING LOW PRESSURE TROUGH AND LAND BREEZES /ACTUALLY SAW TEMPS DIP BLO ZERO OVR PARTS OF INTERIOR EASTERN UPR MICHIGAN THIS MORNING SHOWING THE CHILL OF THE AIRMASS/. AS THE MORNING WEARS ON...INCREASING SOUTH WINDS WILL CONVERGE WITH ENE WINDS OVR LK SUPERIOR RESULTING IN DOMINANT BAND OF SNOW OVR TIP OF KEWEENAW. ALREADY SEEING ECHOES ON MQT RADAR NEAR COPPER HARBOR BUT NOTHING YET PER THE KEWEENAW CO SHERIFF IN EAGLE RIVER. 00Z NAM SEEMED TOO QUICK IN SWINGING DOMINANT BAND BACK TO SOUTH THIS AFTN. 06Z NAM ADJUSTED AND NOW LOOKS LIKE PREFERRED 00Z GEM-REGIONAL AND LOCAL WRF-ARW AND RUC13. UPSHOT IS HEAVIER SNOW HANGS OUT ON TIP OF KEWEENAW THROUGH MIDDAY THEN SINKS SOUTH WITH MORE BRIEF HEAVIER SNOW SOUTH OF CALUMET BY MID-LATE AFTN. OVERALL THE GOING LK EFFECT SNOW ADVY LOOKS GOOD...THOUGH ISOLD AMOUNTS UP TO 10 INCHES NOT OUT QUESTION IF BAND STAYS IN SAME LOCATION. NOT ALL ABOUT LK SUPERIOR THOUGH AS LK MICHIGAN COULD BE INTERESTING AS WELL. SOUTH WINDS FORMING ON LK MICHIGAN ARE LEADING TO CONCERNS THAT LK EFFECT...POSSIBLY HEAVY...COULD IMPACT PARTS OF DELTA AND SOUTHERN SCHOOLCRAFT INTO THIS AFTN. GRB/APX RADAR ALREADY SHOWING SIGNS OF LK EFFECT MESO FEATURES ALONG DOOR PENINSULA AND ALONG NW SHORE OF NORTHERN LOWER MICHIGAN. RUC13 SFC CONVERGENCE FIELD DOING VERY NICE JOB OF PEGGING THESE AREAS AND IT SHOWS THEM MERGING OVER FAR NORTHERN LK MICHIGAN AFT 15Z AND AFFECTING MAINLY GARDEN PENINSULA ACROSS SOUTHERN SCHOOLCRAFT ZONE THIS AFTN. WAS VERY CLOSE TO GO WITH ADVY...BUT CONFIDENCE WAS NOT THERE AS THESE IS UNCERTAINTY IN HOW FAR NORTH THESE CIRCULATIONS WILL GET. RUC FCST IS VERIFYING WELL THOUGH AND DOES GET A LOT OF MERIT. SO...WILL PASS THIS ON TO DAYSHIFT AND LET THEM SEE HOW THINGS LOOK AFT DAYBREAK. PUT OUT A STRONGLY WORDED SPS AND MENTIONED THAT EITHER ADVY/WARNING COULD BE NEEDED LATER TODAY. ANYTHING IS POSSIBLE IN THIS KIND OF SETUP. TONIGHT WILL BASICALLY BE AN EXTENSION OF HOW LK EFFECT DEVELOPS TODAY...SO IT IS STILL KIND OF UNCERTAIN. LEANED ON NCEP HIGH RES WRF-ARW AND NMM RUNS AS WELL AS NAM WHICH COMES BACK INTO LINE WITH GOING THINKING. GENERALLY...SFC TROUGH SHOULD MOVE TO EASTERN LK SUPERIOR ALLOWING WINDS TO BECOME MORE NW OR WEST OVR MUCH OF UPR MICHIGAN. FIRST IMPACT WILL BE TO SHUNT LK EFFECT OFF LK MICHIGAN BACK TO THE SOUTH. HAVE CHANCES VERY EARLY IN THE EVENING...THEN DROP THEM TO SLIGHTS BY LATE EVENING. FARTHER NORTH...LK EFFECT SNOW SHOWERS WILL BE AFFECTING NORTHWEST CWA LATE AFTN/EARLY EVENING AND SHOULD SINK TOWARD NCNTRL UPR MICHIGAN...BIG BAY/MARQUETTE THROUGH THE EVENING AND OVERNIGHT HOURS AND EVENTUALLY MAKE IT ONSHORE TO EAST OF MARQUETTE TOWARD MUNISING AND GRAND MARAIS LATER TONIGHT. MODERATE ACCUMS COULD OCCUR TONIGHT FOR HIGHER TERRAIN OF WEST...VCNTY OF PORCUPINE MTS AND SETUP SEEMS GOOD FOR CONVERGENT BAND OF SNOW TO AFFECT GOOD PART OF BARAGA COUNTY...MAYBE EVEN RIGHT ALONG LK SHORE AT BARAGA/L`ANSE AS WELL. FOR NOW HAVE 2-4 INCHES IN THERE FOR THESE AREAS THIS EVENING. LOCALLY HEAVY SNOW MAY SPREAD TO BIG BAY/MARQUETTE LATER TONIGHT AS CONVERGENCE MAXIMIZES BTWN NW WINDS OVER LK SUPERIOR AND POSSIBLE LAND BREEZE OVER CNTRL UPR MICHIGAN. INLAND FM ALL THE LK EFFECT AND CLOUDS...SOME CLEARING AND LIGHTER WINDS MAY ALLOW TEMPS TO FALL INTO THE SINGLE DIGITS TOWARD WI BORDER AND OVER INTERIOR EASTERN CWA. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 505 AM EST THU NOV 28 2013 FRIDAY...A SPRAWLING SFC HIGH FROM NRN ONTARIO INTO THE OHIO VALLEY WILL RESULT IN A VERY WEAK GRADIENT ACROSS THE NRN GREAT LAKES. THE HIGH RES MODELS SUGGEST THAT THE CIRCULATION AROUND A LAKE INDUCED LOW OR TROUGH OVER SE LAKE SUPERIOR COULD FOCUS LES BANDS ANYWHERE FROM MARQUETTE TO MUNISING. IF THE LOW LEVEL CONVERGENCE IS STRONG ENOUGH THERE MAY BE A PERIOD OF HEAVY SNOW. HOWEVER...CONFIDENCE IN THE LOCATION AND DURATION OF SUCH A BAND IS LOW. SO...FCST SNOWFALL AMOUNTS WERE LIMITED TO AROUND AN INCH. DEVELOPING SRLY FLOW IN THE AFTERNOON WILL PUSH THE REMAINING LES OFFSHORE. ANY SNOWBANDS MOVING INTO THE WEST SHOULD ALSO WEAKEN AND POSSIBLY LINGER ALONG THE SHORELINE UNTIL AFTERNOON WHEN OFF SHORE WINDS STRENGTHEN. 850 MB WAA WILL INCREASE IN THE AFTERNOON AS WEAK MID LEVEL RIDGING MOVES BACK OVER THE AREA AND A SFC HIGH BUILDS INTO THE ERN LAKES. HIGH TEMPS ARE EXPECTED TO REBOUND INTO THE MID AND UPPER 20S. FRI NIGHT AND SAT...THE MODELS WERE IN GOOD AGREEMENT WITH THE NEXT CLIPPER SHORTWAVE TROUGH SLIDING ACROSS NRN LAKE SUPERIOR LATE IN THE DAY ON SATURDAY. LIGHT SNOW DEVELOPING OVER SCNTRL CANADA IN THE WAA PATTERN AHEAD OF THE SHORTWAVE WILL SPREAD SNOW ACROSS NRN LAKE SUPERIOR FRI NIGHT PERHAPS BRUSHING THE NRN AND ERN COUNTIES WITH SOME LIGHT SNOW LATE FRI NIGHT INTO SAT. THE STRONGER FORCING AND BETTER SNOW POTENTIAL IS EXPECTED TO REMAIN NORTH OF LAKE SUPERIOR. HOWEVER...THERE MAY ALSO BE A PERIOD OF LAKE ENAHCNED SNOW INTO THE ERN CWA FROM LATE FRI NIGHT INTO SAT WITH SSW LOW LEVEL FLOW OFF OF LAKE MI VEERING TO THE SW. THE LONG FETCH WILL BE FAVORABLE BUT INSTABILITY WILL BE LIMITED WITH RELATIVELY DRY AIR OVER THE AREA BEFORE THE SHRTWV ARRIVES AND WAA PUSHING 850 MB TEMPS -8C TO -5C. SAT NIGHT...SOME LIGHT LAKE EFFECT SNOW SHOWERS ARE POSSIBLE IN THE WAKE OF THE SFC TROUGH AS WINDS VEER FROM NW TO N AND 850 MB TEMPS DROP FROM -10C TO -12C. WITH ONLY MARGINAL INSTABILITY...ONLY CHANCE POPS WERE INCLUDED. SUN INTO MON...AS HIGH PRES BUILDS INTO NRN ONTARIO WINDS WILL CONTINUE TO VEER FROM NNE TO E. 850 MB TEMPS AROUND -12C WILL PROVIDE JUST ENOUGH INSTABILITY TO KEEP LES CHANCES GOING ACROSS NORTH CENTRAL UPPER MICHIGAN AND THE KEWEENAW. NEAR NORMAL TEMPS ARE EXPECTED WITH HIGHS AROUND 30 TO THE LOWER 30S AND LOWS IN THE LOWER 20S. TUE AND WED...MODELS DIFFER WITH THE APPROACH OF THE NEXT SHORTWAVE EMERGING FROM THE WRN CONUS TROF. THE GFS INDICATES A MORE POSITIVE-TILT WRN CONUS TROF AND LESS AMPLIFICATION OF RIDGE DOWNSTREAM ALLOWING FOR A QUICKER ADVANCE OF A SHORTWAVE AND ASSOCIATED FRONTAL SYSTEM INTO THE WRN LAKES. THE ECMWF INDICATES A MORE AMPLIFIED PATTERN ACROSS THE CONUS WITH A SLOWER ADVANCE OF THE SHORTWAVE MOVING TOWARD THE WRN LAKES. THE FCST CONTINUED TO USE A MDLS CONSENSUS THAT REFLECTS A SLIGHTLY LATER ARRIVAL OF PCPN CHANCES FROM TUE NIGHT INTO WED. THE MODELS ALSO TRENDED TOWARD A LESS AMPLIFIED SOLUTION WITH COLDER AIR ACROSS THE NRN LAKES WHICH WOULD REDUCE THE CHANCE FOR ANY RAIN. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 649 AM EST THU NOV 28 2013 FCST WILL BE A CHALLENGE OVER THE NEXT 24HRS. WITH DISTURBANCE APPROACHING FROM THE NW...WINDS HAVE SWUNG AROUND TO A LIGHT S TO SW DIRECTION. -SN ASSOCIATED WITH APPROACHING DISTURBANCE WILL AFFECT ALL THE TAF SITES WITH MAINLY MVFR CONDITIONS THIS MORNING. OTHERWISE...FOCUS WILL SHIFT TO MESOLOW DEVELOPING OVER WRN LAKE SUPERIOR THIS MORNING. AS THE LOW SHIFTS INTO WRN UPPER MI THIS AFTN...A PERIOD OF MDT TO POTENTIALLY HVY SNOW WILL IMPACT KIWD/KCMX AS WINDS SHIFT TO AN ONSHORE DIRECTION. FOR NOW...INCLUDED IFR CONDITIONS AT BOTH TERMINALS FOR SEVERAL HRS IN THE AFTN TO EVENING. OCNL LIFR CONDITIONS NOT OUT OF THE QUESTION. BEST SHOT OF THAT WILL BE AT CMX SO INCLUDED TEMPO GROUP. KSAW SHOULD GENERALLY REMAIN VFR INTO THE AFTN BEFORE WINDS BECOME LIGHT NRLY. MIGHT BE A PERIOD OF HEAVIER SHSN/LOWER CONDITIONS AT KSAW THIS EVENING. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 343 PM EST WED NOV 27 2013 STRONGER N WINDS WILL CONTINUE TO SLOWLY DIMINISH THIS EVENING. A RIDGE OF HIGH PRESSURE WILL EXTEND OVER LAKE SUPERIOR THIS EVENING...WHILE A WEAK LOW OVER THE EASTERN DAKOTAS PUSHES ACROSS THE UPPER GREAT LAKES LATE TONIGHT THROUGH THURSDAY. LARGER HIGH PRESSURE EXTENDING ACROSS MUCH OF CENTRAL CANADA THROUGH THE CENTRAL PLAINS THURSDAY AFTERNOON WILL SWING ACROSS THE UPPER GREAT LAKES THURSDAY NIGHT...BEFORE EXITING TO THE LOWER GREAT LAKES AND NEW ENGLAND STATES FRIDAY AFTERNOON THROUGH SATURDAY. EXPECT A LOW OVER LAKE WINNIPEG FRIDAY NIGHT TO PUSH ACROSS SOUTHERN ONTARIO AND LAKE SUPERIOR SATURDAY AND SATURDAY EVENING. THERE IS THE POTENTIAL FOR 30KT S GUSTS DURING THE DAY SATURDAY. FOR SUNDAY AND MONDAY...HIGH PRESSURE SCOOTING ACROSS ONTARIO WILL PUSH A RIDGE OVER LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ001. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...JLB AVIATION...JLA MARINE...KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
521 AM EST THU NOV 28 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 520 AM EST THU NOV 28 2013 LARGE SCALE FIRST...THEN LETS TALK ABOUT MESOSCALE AND LK EFFECT ISSUES THAT ARE PLENTY. SHORTWAVE AND LOW PRESSURE TROUGH IN COOL NW FLOW CLOSING IN ON WESTERN UPR MICHIGAN. BATCH OF LGT SNOW EXTENDS FROM FAR WEST CWA TO THE NORTHWEST ALONG MN/ONTARIO BORDER. SO WIDESPREAD LGT SNOW WILL IMPACT THOSE TRAVELING THIS THANKSGIVING MORNING...ESPECIALLY OVER WESTERN CWA AND TOWARD WISCONSIN BORDER WHERE BETTER FORCING WITH THE SHORTWAVE RESIDES. OMEGA IN THE H7-H6 LAYER EXITS AFT 15Z...LEAVING MOSTLY NEGATIVE LARGE SCALE FORCING THROUGH TONIGHT. NOW ONTO THE MESOSCALE AND LAKE EFFECT ISSUES. IT IS NEVER A GOOD THING WHEN A LARGER SCALE TROUGH MERGES INTO AN UNSTABLE AND LIGHT WIND LAKE EFFECT ENVIRONMENT. CRAZY THINGS CAN HAPPEN. TODAY MAY END UP BEING ONE OF THESE DAYS. ONLY TIME WILL TELL. LK EFFECT IS ALREADY ONGOING. FIRST FOR LK SUPERIOR...STRONG MESOLOW CIRCULATION IS TAKING OFF JUST OFFSHORE OF MUNSING AND MAY ACTUALLY BE CLIPPING GRAND ISLAND. THIS IS LIKELY THE BEGINNING OF EVENTUAL HEAVY SNOW BAND TO IMPACT FAR NORTHERN KEWEENAW PENINSULA...VCNTY OF DELAWARE AND COPPER HARBOR...THOUGH MIDDAY. WINDS OVER LK SUPERIOR ARE MAINLY NE AT THIS TIME...BUT TOWARD THE SOUTH SHORE ARE BECOMING VARIABLE OR EVEN SOUTH THANKS TO APPROACHING LOW PRESSURE TROUGH AND LAND BREEZES /ACTUALLY SAW TEMPS DIP BLO ZERO OVR PARTS OF INTERIOR EASTERN UPR MICHIGAN THIS MORNING SHOWING THE CHILL OF THE AIRMASS/. AS THE MORNING WEARS ON...INCREASING SOUTH WINDS WILL CONVERGE WITH ENE WINDS OVR LK SUPERIOR RESULTING IN DOMINANT BAND OF SNOW OVR TIP OF KEWEENAW. ALREADY SEEING ECHOES ON MQT RADAR NEAR COPPER HARBOR BUT NOTHING YET PER THE KEWEENAW CO SHERIFF IN EAGLE RIVER. 00Z NAM SEEMED TOO QUICK IN SWINGING DOMINANT BAND BACK TO SOUTH THIS AFTN. 06Z NAM ADJUSTED AND NOW LOOKS LIKE PREFERRED 00Z GEM-REGIONAL AND LOCAL WRF-ARW AND RUC13. UPSHOT IS HEAVIER SNOW HANGS OUT ON TIP OF KEWEENAW THROUGH MIDDAY THEN SINKS SOUTH WITH MORE BRIEF HEAVIER SNOW SOUTH OF CALUMET BY MID-LATE AFTN. OVERALL THE GOING LK EFFECT SNOW ADVY LOOKS GOOD...THOUGH ISOLD AMOUNTS UP TO 10 INCHES NOT OUT QUESTION IF BAND STAYS IN SAME LOCATION. NOT ALL ABOUT LK SUPERIOR THOUGH AS LK MICHIGAN COULD BE INTERESTING AS WELL. SOUTH WINDS FORMING ON LK MICHIGAN ARE LEADING TO CONCERNS THAT LK EFFECT...POSSIBLY HEAVY...COULD IMPACT PARTS OF DELTA AND SOUTHERN SCHOOLCRAFT INTO THIS AFTN. GRB/APX RADAR ALREADY SHOWING SIGNS OF LK EFFECT MESO FEATURES ALONG DOOR PENINSULA AND ALONG NW SHORE OF NORTHERN LOWER MICHIGAN. RUC13 SFC CONVERGENCE FIELD DOING VERY NICE JOB OF PEGGING THESE AREAS AND IT SHOWS THEM MERGING OVER FAR NORTHERN LK MICHIGAN AFT 15Z AND AFFECTING MAINLY GARDEN PENINSULA ACROSS SOUTHERN SCHOOLCRAFT ZONE THIS AFTN. WAS VERY CLOSE TO GO WITH ADVY...BUT CONFIDENCE WAS NOT THERE AS THESE IS UNCERTAINTY IN HOW FAR NORTH THESE CIRCULATIONS WILL GET. RUC FCST IS VERIFYING WELL THOUGH AND DOES GET A LOT OF MERIT. SO...WILL PASS THIS ON TO DAYSHIFT AND LET THEM SEE HOW THINGS LOOK AFT DAYBREAK. PUT OUT A STRONGLY WORDED SPS AND MENTIONED THAT EITHER ADVY/WARNING COULD BE NEEDED LATER TODAY. ANYTHING IS POSSIBLE IN THIS KIND OF SETUP. TONIGHT WILL BASICALLY BE AN EXTENSION OF HOW LK EFFECT DEVELOPS TODAY...SO IT IS STILL KIND OF UNCERTAIN. LEANED ON NCEP HIGH RES WRF-ARW AND NMM RUNS AS WELL AS NAM WHICH COMES BACK INTO LINE WITH GOING THINKING. GENERALLY...SFC TROUGH SHOULD MOVE TO EASTERN LK SUPERIOR ALLOWING WINDS TO BECOME MORE NW OR WEST OVR MUCH OF UPR MICHIGAN. FIRST IMPACT WILL BE TO SHUNT LK EFFECT OFF LK MICHIGAN BACK TO THE SOUTH. HAVE CHANCES VERY EARLY IN THE EVENING...THEN DROP THEM TO SLIGHTS BY LATE EVENING. FARTHER NORTH...LK EFFECT SNOW SHOWERS WILL BE AFFECTING NORTHWEST CWA LATE AFTN/EARLY EVENING AND SHOULD SINK TOWARD NCNTRL UPR MICHIGAN...BIG BAY/MARQUETTE THROUGH THE EVENING AND OVERNIGHT HOURS AND EVENTUALLY MAKE IT ONSHORE TO EAST OF MARQUETTE TOWARD MUNISING AND GRAND MARAIS LATER TONIGHT. MODERATE ACCUMS COULD OCCUR TONIGHT FOR HIGHER TERRAIN OF WEST...VCNTY OF PORCUPINE MTS AND SETUP SEEMS GOOD FOR CONVERGENT BAND OF SNOW TO AFFECT GOOD PART OF BARAGA COUNTY...MAYBE EVEN RIGHT ALONG LK SHORE AT BARAGA/L`ANSE AS WELL. FOR NOW HAVE 2-4 INCHES IN THERE FOR THESE AREAS THIS EVENING. LOCALLY HEAVY SNOW MAY SPREAD TO BIG BAY/MARQUETTE LATER TONIGHT AS CONVERGENCE MAXIMIZES BTWN NW WINDS OVER LK SUPERIOR AND POSSIBLE LAND BREEZE OVER CNTRL UPR MICHIGAN. INLAND FM ALL THE LK EFFECT AND CLOUDS...SOME CLEARING AND LIGHTER WINDS MAY ALLOW TEMPS TO FALL INTO THE SINGLE DIGITS TOWARD WI BORDER AND OVER INTERIOR EASTERN CWA. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 505 AM EST THU NOV 28 2013 FRIDAY...A SPRAWLING SFC HIGH FROM NRN ONTARIO INTO THE OHIO VALLEY WILL RESULT IN A VERY WEAK GRADIENT ACROSS THE NRN GREAT LAKES. THE HIGH RES MODELS SUGGEST THAT THE CIRCULATION AROUND A LAKE INDUCED LOW OR TROUGH OVER SE LAKE SUPERIOR COULD FOCUS LES BANDS ANYWHERE FROM MARQUETTE TO MUNISING. IF THE LOW LEVEL CONVERGENCE IS STRONG ENOUGH THERE MAY BE A PERIOD OF HEAVY SNOW. HOWEVER...CONFIDENCE IN THE LOCATION AND DURATION OF SUCH A BAND IS LOW. SO...FCST SNOWFALL AMOUNTS WERE LIMITED TO AROUND AN INCH. DEVELOPING SRLY FLOW IN THE AFTERNOON WILL PUSH THE REMAINING LES OFFSHORE. ANY SNOWBANDS MOVING INTO THE WEST SHOULD ALSO WEAKEN AND POSSIBLY LINGER ALONG THE SHORELINE UNTIL AFTERNOON WHEN OFF SHORE WINDS STRENGTHEN. 850 MB WAA WILL INCREASE IN THE AFTERNOON AS WEAK MID LEVEL RIDGING MOVES BACK OVER THE AREA AND A SFC HIGH BUILDS INTO THE ERN LAKES. HIGH TEMPS ARE EXPECTED TO REBOUND INTO THE MID AND UPPER 20S. FRI NIGHT AND SAT...THE MODELS WERE IN GOOD AGREEMENT WITH THE NEXT CLIPPER SHORTWAVE TROUGH SLIDING ACROSS NRN LAKE SUPERIOR LATE IN THE DAY ON SATURDAY. LIGHT SNOW DEVELOPING OVER SCNTRL CANADA IN THE WAA PATTERN AHEAD OF THE SHORTWAVE WILL SPREAD SNOW ACROSS NRN LAKE SUPERIOR FRI NIGHT PERHAPS BRUSHING THE NRN AND ERN COUNTIES WITH SOME LIGHT SNOW LATE FRI NIGHT INTO SAT. THE STRONGER FORCING AND BETTER SNOW POTENTIAL IS EXPECTED TO REMAIN NORTH OF LAKE SUPERIOR. HOWEVER...THERE MAY ALSO BE A PERIOD OF LAKE ENAHCNED SNOW INTO THE ERN CWA FROM LATE FRI NIGHT INTO SAT WITH SSW LOW LEVEL FLOW OFF OF LAKE MI VEERING TO THE SW. THE LONG FETCH WILL BE FAVORABLE BUT INSTABILITY WILL BE LIMITED WITH RELATIVELY DRY AIR OVER THE AREA BEFORE THE SHRTWV ARRIVES AND WAA PUSHING 850 MB TEMPS -8C TO -5C. SAT NIGHT...SOME LIGHT LAKE EFFECT SNOW SHOWERS ARE POSSIBLE IN THE WAKE OF THE SFC TROUGH AS WINDS VEER FROM NW TO N AND 850 MB TEMPS DROP FROM -10C TO -12C. WITH ONLY MARGINAL INSTABILITY...ONLY CHANCE POPS WERE INCLUDED. SUN INTO MON...AS HIGH PRES BUILDS INTO NRN ONTARIO WINDS WILL CONTINUE TO VEER FROM NNE TO E. 850 MB TEMPS AROUND -12C WILL PROVIDE JUST ENOUGH INSTABILITY TO KEEP LES CHANCES GOING ACROSS NORTH CENTRAL UPPER MICHIGAN AND THE KEWEENAW. NEAR NORMAL TEMPS ARE EXPECTED WITH HIGHS AROUND 30 TO THE LOWER 30S AND LOWS IN THE LOWER 20S. TUE AND WED...MODELS DIFFER WITH THE APPROACH OF THE NEXT SHORTWAVE EMERGING FROM THE WRN CONUS TROF. THE GFS INDICATES A MORE POSITIVE-TILT WRN CONUS TROF AND LESS AMPLIFICATION OF RIDGE DOWNSTREAM ALLOWING FOR A QUICKER ADVANCE OF A SHORTWAVE AND ASSOCIATED FRONTAL SYSTEM INTO THE WRN LAKES. THE ECMWF INDICATES A MORE AMPLIFIED PATTERN ACROSS THE CONUS WITH A SLOWER ADVANCE OF THE SHORTWAVE MOVING TOWARD THE WRN LAKES. THE FCST CONTINUED TO USE A MDLS CONSENSUS THAT REFLECTS A SLIGHTLY LATER ARRIVAL OF PCPN CHANCES FROM TUE NIGHT INTO WED. THE MODELS ALSO TRENDED TOWARD A LESS AMPLIFIED SOLUTION WITH COLDER AIR ACROSS THE NRN LAKES WHICH WOULD REDUCE THE CHANCE FOR ANY RAIN. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1206 AM EST THU NOV 28 2013 FCST WILL BE A CHALLENGE OVER THE NEXT 24HRS. WITH DISTURBANCE APPROACHING FROM THE NW...WINDS ARE IN THE PROCESS OF SWINGING AROUND TO A LIGHT S TO SW DIRECTION. AS A RESULT...LAKE EFFECT SNOW SHOWERS FOR THE TIME BEING HAVE ENDED AT KIWD/KCMX/KSAW...AND VFR CONDITIONS SHOULD GENERALLY PREVAIL OVERNIGHT. HOWEVER...-SN ASSOCIATED WITH APPROACHING DISTURBANCE MAY AFFECT KIWD OVERNIGHT INTO THE MORNING...BRINGING MVFR CONDITIONS. OTHERWISE...FOCUS WILL SHIFT TO MESOLOW DEVELOPING OVER WRN LAKE SUPERIOR OVERNIGHT. AS THE LOW SHIFTS INTO WRN UPPER MI THIS AFTN...A PERIOD OF MDT TO POTENTIALLY HVY SNOW WILL IMPACT KIWD/KCMX AS WINDS SHIFT TO AN ONSHORE DIRECTION. FOR NOW...INCLUDED IFR CONDITIONS AT BOTH TERMINALS FOR SEVERAL HRS IN THE AFTN TO EVENING. OCNL LIFR CONDITIONS NOT OUT OF THE QUESTION. KSAW SHOULD GENERALLY REMAIN VFR INTO THE AFTN BEFORE WINDS BECOME LIGHT NRLY. MIGHT BE A PERIOD OF HEAVIER SHSN/LOWER CONDITIONS AT KSAW THIS EVENING. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 343 PM EST WED NOV 27 2013 STRONGER N WINDS WILL CONTINUE TO SLOWLY DIMINISH THIS EVENING. A RIDGE OF HIGH PRESSURE WILL EXTEND OVER LAKE SUPERIOR THIS EVENING...WHILE A WEAK LOW OVER THE EASTERN DAKOTAS PUSHES ACROSS THE UPPER GREAT LAKES LATE TONIGHT THROUGH THURSDAY. LARGER HIGH PRESSURE EXTENDING ACROSS MUCH OF CENTRAL CANADA THROUGH THE CENTRAL PLAINS THURSDAY AFTERNOON WILL SWING ACROSS THE UPPER GREAT LAKES THURSDAY NIGHT...BEFORE EXITING TO THE LOWER GREAT LAKES AND NEW ENGLAND STATES FRIDAY AFTERNOON THROUGH SATURDAY. EXPECT A LOW OVER LAKE WINNIPEG FRIDAY NIGHT TO PUSH ACROSS SOUTHERN ONTARIO AND LAKE SUPERIOR SATURDAY AND SATURDAY EVENING. THERE IS THE POTENTIAL FOR 30KT S GUSTS DURING THE DAY SATURDAY. FOR SUNDAY AND MONDAY...HIGH PRESSURE SCOOTING ACROSS ONTARIO WILL PUSH A RIDGE OVER LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ001. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...JLB AVIATION...ROLFSON MARINE...KF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1136 AM CST THU NOV 28 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 250 AM CST THU NOV 28 2013 MAIN ISSUE FOR THE SHORT TERM IS HOW LONG WILL IT TAKE FOR THE CLOUDS TO CLEAR OUT TODAY. A 1018MB SFC LOW HAS BEEN MAKING SLOW BUT STEADY PROGRESS ACROSS NRN IOWA OVERNIGHT AND WILL CONTINUE ON A TRACK TOWARD SRN LAKE MICHIGAN BY THE AFTERNOON. AN INVERTED SFC TROUGH HAS BEEN WORKING EAST ACROSS MN IN CONCERT WITH THE IOWA LOW AND HAS HELPED MAINTAIN THE STRATUS NORTH OF THE LOW. BEHIND THIS INVERTED TROUGH...ANOTHER CANADIAN HIGH IS BUILDING SOUTH ACROSS THE DAKOTAS. RH TIME-HEIGHT PROFILES SHOW PLENTY OF DRYING AND SUBSIDENCE OCCURRING AS THIS HIGH MOVES IN...WHICH IS WHY THE QUESTION WITH THE CLOUDS IS HOW LONG DO THEY STICK AROUND. FOR NOW...HAVE A RATHER CLOUDY FORECAST THROUGH 18Z...BUT QUICKLY START TO IMPROVE THINGS FROM WEST TO EAST THIS AFTERNOON...IN LINE WITH WHAT THE RAP 925-850 MB RH SHOWS. ALTHOUGH THERE IS CURRENTLY A SEA OF LIGHT SNOW REPORTS ACROSS NRN MN AND NODAK...THESE ARE NOT EXPECTED TO MAKE IT INTO THE MPX AREA. THE REASON FOR THIS IS THAT SFC TEMPERATURES WHERE THE SNOW IS BEING REPORTED RIGHT NOW ARE ALL IN THE LOW TO MID TEENS...WHICH MEANS UP THERE...THE DENDRITIC GROWTH ZONE IS DOWN AT THE SURFACE AND EXTENDS UP THROUGH THE CLOUD LAYER. ADD IN THE WEAK LIFT ALONG/AHEAD OF THE INVERTED TROUGH WITH A DGZ ALL THE WAY DOWN TO THE SURFACE AND YOU END UP WITH THE SCENARIO WHERE ALL CLOUDS HAVE SNOW. COMING DOWN TO CENTRAL/SRN MN...SFC TEMPS DOWN HERE ARE ALL IN THE UPPER TEENS/LOWER 20S...OUTSIDE OF THE DGZ. THE SHALLOWER DGZ THAT DOES NOT EXTEND TO THE SFC HAS ALLOWED THE CLOUDS DOWN HERE TO REMAIN SNOW FREE. CAA AT THE MOMENT IS NOT STRONG ENOUGH TO COOL OUR SFC TEMPS DOWN INTO THE DGZ BEFORE WE START GETTING SOME SOLAR HEATING...SO DO NOT ANTICIPATE THE SNOW/FLURRY REPORTS TO MAKE IT MUCH FARTHER SOUTH THAN THEY CURRENTLY ARE. THE COMBINATION OF WEAK CAA AND CLOUD COVER WILL AGAIN LIMIT THE DIURNAL TEMPERATURE INCREASE AGAIN TODAY...WITH TEMPERATURES THIS AFTERNOON ONLY EXPECTED TO INCREASE ABOUT 5 OR 10 DEGREES ABOVE THEIR CURRENT VALUES THIS MORNING. TONIGHT...YET ANOTHER SFC RIDGE AXIS WILL BE CENTERED ACROSS THE AREA...RESULTING IN ANOTHER NIGHT WITH LOWS IN THE SINGLE DIGITS TO LOWER TEENS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 250 AM CST THU NOV 28 2013 THE LONG TERM WILL BEGIN TRANQUIL BUT WILL LIKELY END RATHER ACTIVE AS A MAJOR PATTERN SHIFT UNFOLDS. HIGH PRESSURE OVER THE GREAT LAKES WILL SLIDE EAST FRIDAY WITH WAA COMMENCING AT THE START OF THE PERIOD. BREEZY SOUTHEAST WINDS WILL BRING HIGHS BACK TO WHERE THEY SHOULD BE IN THE UPPER 20S TO MID 30S. A WEAK CLIPPER SYSTEM WILL DIVE SOUTHEAST ACROSS NORTHERN LAKE SUPERIOR FRIDAY NIGHT AND EARLY SATURDAY. FORECAST SOUNDINGS SHOW SUFFICIENT MOISTENING IN THE LOWER LEVELS AFTER MIDNIGHT TO SUPPORT A CHANCE OF FREEZING DRIZZLE OR FLURRIES OVER WESTERN WISCONSIN. HOWEVER...KEPT PROBABILITIES RATHER LOW DUE TO THE SOURCE REGION OF THIS MOISTURE BEING FROM THE SPRAWLING EASTERN CONUS HIGH PRESSURE SYSTEM THAT DROVE A COLD FRONT THROUGH THE GULF AND CUBA. NEEDLESS TO SAY...NOT A WHOLE LOT OF MOISTURE TO BE FOUND ANYWHERE NEARBY. SURFACE RIDGING WILL RETURN SATURDAY AND SUNDAY WITH TEMPERATURES REMAINING NEAR NORMAL. MEANWHILE...A POTENT UPPER LOW TRAVERSING ALASKA WILL DIVE SOUTHEAST ALONG THE BRITISH COLOMBIAN COAST INTO THE PACIFIC NORTHWEST AND THE CENTRAL ROCKIES BY THE MIDDLE OF NEXT WEEK. THIS WILL BE REPLACED WITH A 570DM RIDGE OVER ALASKA MONDAY AND BUILDING HEIGHTS ACROSS THE CENTRAL AND EASTERN CONUS FOR LATE WEEK. A SIZABLE CHUNK OF ARCTIC AIR WILL DISLODGE FROM THE POLAR VORTEX AND SINK SOUTH TOWARD THE NORTHERN CONUS BY LATE IN THE LONG TERM. FOLLOWED THE ECMWF/GEM/GFS ENSEMBLE SOLUTION WITH A MORE ZONAL LOOK ACROSS THE NORTHERN TIER OF STATES AS OPPOSED TO THE OPERATIONAL GFS WHICH SEEMED TOO AMPLIFIED DURING MID TO LATE WEEK. SOUTHERLY FLOW AHEAD OF THE WESTERN TROUGH AND MODEST ISENTROPIC LIFT IN THE PRESENCE OF INCREASING MID LEVEL MOISTURE LOOKS INCREASINGLY LIKELY WILL ALLOW FOR PERIODS OF LIGHT SNOW ALONG AN EAST-WEST STATIONARY BOUNDARY FROM SUNDAY NIGHT THROUGH TUESDAY NIGHT. DUE TO A SURFACE HIGH ANCHORED TO THE NORTH...EASTERLY SURFACE FLOW WILL BRING A CONTINUED SUPPLY OF DRY BOUNDARY LAYER AIR AND THUS AMOUNTS WILL BE LIGHT DURING THIS PERIOD. SURFACE LOW ORGANIZING TO THE LEE OF THE ROCKIES IN ADVANCE OF THE ROCKIES TROUGH MAY EJECT NORTHEAST TOWARD THE GREAT LAKES IN THE WEDNESDAY NIGHT/THURSDAY TIMEFRAME. ECMWF BRINGS A PRETTY IMPRESSIVE SYSTEM THROUGH WITH SIGNIFICANT ACCUMULATING SNOW. GEM IS A BIT FURTHER SOUTH. REGARDLESS...FOLLOWING THIS POTENTIAL STORM WILL BE AN EXPANSIVE INTRUSION OF ARCTIC AIR FOR MOST OF THE CENTRAL AND WESTERN CONUS. THIS SIGNAL HAS BEEN SOLID IN CLIMATE FORECASTING MODELS FOR WEEKS NOW AND AS CPC POINTS OUT IN THEIR 6-10 AND 8-14 DAY OUTLOOKS...PROBABILITY OF OCCUR RANCE IS VERY HIGH. IF WE CAN GET A SNOWPACK DOWN BEFORE THIS ARRIVES...TEMPS COULD BE 20-30+ DEGREES BELOW AVERAGE FOR EARLY DECEMBER. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1120 AM CST THU NOV 28 2013 VFR/MVFR CIGS MOVING SOUTHWARD ACROSS EASTERN MN MAY ALLOW FOR SOME CIGS ARND 2.5 TEMPORARY THIS AFTN. THE BEST CHC OF MVFR CIGS WILL OCCUR AT KSTC/KRNH DURING THE EARLY AFTN. ELSEWHERE...MORE SCATTERED CLDS ARE EXPECTED. BY 22Z...ANY MINOR DAYTIME HEATING WILL QUICKLY ERODE THE CLDS WITH ONLY CIRRUS EXPECTED AFT 00Z. WINDS WILL QUICKLY BECOME NEAR CALM OVERNIGHT...BEFORE SHIFTING TO THE S/SSE BY DAWN AND INCREASE TO 14-16 KTS IN WESTERN MN...AND ARND 12 KTS IN EASTERN MN. KMSP... MVFR CIGS AS CLOSE AS KMIC WHICH MAY AFFECT THE AIRPORT GROUNDS DURING THE EARLY AFTN HRS. BEST TIME FRAME WILL OCCUR BETWEEN 18-20Z WITH CIGS ARND 2.5K. OTHERWISE...SKIES WILL QUICKLY BECOME CLR THIS EVENING WITH CIRRUS MOVING IN AFT MIDNIGHT. GUSTY WINDS ARND 14-16 KTS THIS AFTN WILL BECOME CALM AND SHIFT TO THE SE BY MORNING...BECOMING GUSTY AGAIN BY THE AFTN. /OUTLOOK FOR KMSP/ SAT...VFR. SW WINDS AT 5-10KTS BECOMING W/NW DURING THE AFT/EVE. SUN...VFR...POSSIBLY MVFR CIGS LATE WITH -SN. WINDS E/SE AT 5KTS. MON...VFR WITH CHC OF MIX PREC LATE WITH MVFR CIGS. SE WNDS 10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM...BORGHOFF AVIATION...JLT
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
529 AM CST THU NOV 28 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 250 AM CST THU NOV 28 2013 MAIN ISSUE FOR THE SHORT TERM IS HOW LONG WILL IT TAKE FOR THE CLOUDS TO CLEAR OUT TODAY. A 1018MB SFC LOW HAS BEEN MAKING SLOW BUT STEADY PROGRESS ACROSS NRN IOWA OVERNIGHT AND WILL CONTINUE ON A TRACK TOWARD SRN LAKE MICHIGAN BY THE AFTERNOON. AN INVERTED SFC TROUGH HAS BEEN WORKING EAST ACROSS MN IN CONCERT WITH THE IOWA LOW AND HAS HELPED MAINTAIN THE STRATUS NORTH OF THE LOW. BEHIND THIS INVERTED TROUGH...ANOTHER CANADIAN HIGH IS BUILDING SOUTH ACROSS THE DAKOTAS. RH TIME-HEIGHT PROFILES SHOW PLENTY OF DRYING AND SUBSIDENCE OCCURRING AS THIS HIGH MOVES IN...WHICH IS WHY THE QUESTION WITH THE CLOUDS IS HOW LONG DO THEY STICK AROUND. FOR NOW...HAVE A RATHER CLOUDY FORECAST THROUGH 18Z...BUT QUICKLY START TO IMPROVE THINGS FROM WEST TO EAST THIS AFTERNOON...IN LINE WITH WHAT THE RAP 925-850 MB RH SHOWS. ALTHOUGH THERE IS CURRENTLY A SEA OF LIGHT SNOW REPORTS ACROSS NRN MN AND NODAK...THESE ARE NOT EXPECTED TO MAKE IT INTO THE MPX AREA. THE REASON FOR THIS IS THAT SFC TEMPERATURES WHERE THE SNOW IS BEING REPORTED RIGHT NOW ARE ALL IN THE LOW TO MID TEENS...WHICH MEANS UP THERE...THE DENDRITIC GROWTH ZONE IS DOWN AT THE SURFACE AND EXTENDS UP THROUGH THE CLOUD LAYER. ADD IN THE WEAK LIFT ALONG/AHEAD OF THE INVERTED TROUGH WITH A DGZ ALL THE WAY DOWN TO THE SURFACE AND YOU END UP WITH THE SCENARIO WHERE ALL CLOUDS HAVE SNOW. COMING DOWN TO CENTRAL/SRN MN...SFC TEMPS DOWN HERE ARE ALL IN THE UPPER TEENS/LOWER 20S...OUTSIDE OF THE DGZ. THE SHALLOWER DGZ THAT DOES NOT EXTEND TO THE SFC HAS ALLOWED THE CLOUDS DOWN HERE TO REMAIN SNOW FREE. CAA AT THE MOMENT IS NOT STRONG ENOUGH TO COOL OUR SFC TEMPS DOWN INTO THE DGZ BEFORE WE START GETTING SOME SOLAR HEATING...SO DO NOT ANTICIPATE THE SNOW/FLURRY REPORTS TO MAKE IT MUCH FARTHER SOUTH THAN THEY CURRENTLY ARE. THE COMBINATION OF WEAK CAA AND CLOUD COVER WILL AGAIN LIMIT THE DIURNAL TEMPERATURE INCREASE AGAIN TODAY...WITH TEMPERATURES THIS AFTERNOON ONLY EXPECTED TO INCREASE ABOUT 5 OR 10 DEGREES ABOVE THEIR CURRENT VALUES THIS MORNING. TONIGHT...YET ANOTHER SFC RIDGE AXIS WILL BE CENTERED ACROSS THE AREA...RESULTING IN ANOTHER NIGHT WITH LOWS IN THE SINGLE DIGITS TO LOWER TEENS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 250 AM CST THU NOV 28 2013 THE LONG TERM WILL BEGIN TRANQUIL BUT WILL LIKELY END RATHER ACTIVE AS A MAJOR PATTERN SHIFT UNFOLDS. HIGH PRESSURE OVER THE GREAT LAKES WILL SLIDE EAST FRIDAY WITH WAA COMMENCING AT THE START OF THE PERIOD. BREEZY SOUTHEAST WINDS WILL BRING HIGHS BACK TO WHERE THEY SHOULD BE IN THE UPPER 20S TO MID 30S. A WEAK CLIPPER SYSTEM WILL DIVE SOUTHEAST ACROSS NORTHERN LAKE SUPERIOR FRIDAY NIGHT AND EARLY SATURDAY. FORECAST SOUNDINGS SHOW SUFFICIENT MOISTENING IN THE LOWER LEVELS AFTER MIDNIGHT TO SUPPORT A CHANCE OF FREEZING DRIZZLE OR FLURRIES OVER WESTERN WISCONSIN. HOWEVER...KEPT PROBABILITIES RATHER LOW DUE TO THE SOURCE REGION OF THIS MOISTURE BEING FROM THE SPRAWLING EASTERN CONUS HIGH PRESSURE SYSTEM THAT DROVE A COLD FRONT THROUGH THE GULF AND CUBA. NEEDLESS TO SAY...NOT A WHOLE LOT OF MOISTURE TO BE FOUND ANYWHERE NEARBY. SURFACE RIDGING WILL RETURN SATURDAY AND SUNDAY WITH TEMPERATURES REMAINING NEAR NORMAL. MEANWHILE...A POTENT UPPER LOW TRAVERSING ALASKA WILL DIVE SOUTHEAST ALONG THE BRITISH COLOMBIAN COAST INTO THE PACIFIC NORTHWEST AND THE CENTRAL ROCKIES BY THE MIDDLE OF NEXT WEEK. THIS WILL BE REPLACED WITH A 570DM RIDGE OVER ALASKA MONDAY AND BUILDING HEIGHTS ACROSS THE CENTRAL AND EASTERN CONUS FOR LATE WEEK. A SIZABLE CHUNK OF ARCTIC AIR WILL DISLODGE FROM THE POLAR VORTEX AND SINK SOUTH TOWARD THE NORTHERN CONUS BY LATE IN THE LONG TERM. FOLLOWED THE ECMWF/GEM/GFS ENSEMBLE SOLUTION WITH A MORE ZONAL LOOK ACROSS THE NORTHERN TIER OF STATES AS OPPOSED TO THE OPERATIONAL GFS WHICH SEEMED TOO AMPLIFIED DURING MID TO LATE WEEK. SOUTHERLY FLOW AHEAD OF THE WESTERN TROUGH AND MODEST ISENTROPIC LIFT IN THE PRESENCE OF INCREASING MID LEVEL MOISTURE LOOKS INCREASINGLY LIKELY WILL ALLOW FOR PERIODS OF LIGHT SNOW ALONG AN EAST-WEST STATIONARY BOUNDARY FROM SUNDAY NIGHT THROUGH TUESDAY NIGHT. DUE TO A SURFACE HIGH ANCHORED TO THE NORTH...EASTERLY SURFACE FLOW WILL BRING A CONTINUED SUPPLY OF DRY BOUNDARY LAYER AIR AND THUS AMOUNTS WILL BE LIGHT DURING THIS PERIOD. SURFACE LOW ORGANIZING TO THE LEE OF THE ROCKIES IN ADVANCE OF THE ROCKIES TROUGH MAY EJECT NORTHEAST TOWARD THE GREAT LAKES IN THE WEDNESDAY NIGHT/THURSDAY TIMEFRAME. ECMWF BRINGS A PRETTY IMPRESSIVE SYSTEM THROUGH WITH SIGNIFICANT ACCUMULATING SNOW. GEM IS A BIT FURTHER SOUTH. REGARDLESS...FOLLOWING THIS POTENTIAL STORM WILL BE AN EXPANSIVE INTRUSION OF ARCTIC AIR FOR MOST OF THE CENTRAL AND WESTERN CONUS. THIS SIGNAL HAS BEEN SOLID IN CLIMATE FORECASTING MODELS FOR WEEKS NOW AND AS CPC POINTS OUT IN THEIR 6-10 AND 8-14 DAY OUTLOOKS...PROBABILITY OF OCCUR RANCE IS VERY HIGH. IF WE CAN GET A SNOWPACK DOWN BEFORE THIS ARRIVES...TEMPS COULD BE 20-30+ DEGREES BELOW AVERAGE FOR EARLY DECEMBER. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 519 AM CST THU NOV 28 2013 HIGH PRESSURE WILL BE MOVING ACROSS THE TERMINALS THIS PERIOD...RESULTING IN YET ANOTHER QUIET TAF PERIOD. MAIN ISSUE FOR TODAY IS WHEN WILL THE VFR STRATUS CLEAR. ALREADY SEEING SOME CLEARING DEVELOP NORTH OF FARGO...AND RAP 925-850 MB RH SHOWS CLEARING DEVELOPING FROM THIS AREA QUICKLY AFTER 15Z OR SO. CURRENT TAFS LOOKED TO HAVE THINGS TIMED WELL WITH RESPECT TO CLEARING SO MADE FEW CHANGES. WILL SEE NW WINDS TODAY THAT WILL GO CALM OVERNIGHT WITH THE HIGH AS SE WINDS RETURN LATE AT MN TERMINALS. KMSP...ABOUT THE ONLY POSSIBLE DEVIATION THAT COULD BE SEEN FROM CURRENT TAF WOULD BE A LATER SCATTERING OUT OF VFR CIGS THAN CURRENTLY INDICATED...BUT AT 5K FT...THEY WILL BE OF MINIMAL IMPACT. /OUTLOOK FOR KMSP/ FRI...VFR. WINDS SE AT 5-10KTS. SAT...VFR. SW WINDS AT 5-10KTS BECOMING W/NW DURING THE AFT/EVE. SUN...VFR. WINDS E/SE AT 5KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM...BORGHOFF AVIATION...MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
414 AM CST THU NOV 28 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 250 AM CST THU NOV 28 2013 MAIN ISSUE FOR THE SHORT TERM IS HOW LONG WILL IT TAKE FOR THE CLOUDS TO CLEAR OUT TODAY. A 1018MB SFC LOW HAS BEEN MAKING SLOW BUT STEADY PROGRESS ACROSS NRN IOWA OVERNIGHT AND WILL CONTINUE ON A TRACK TOWARD SRN LAKE MICHIGAN BY THE AFTERNOON. AN INVERTED SFC TROUGH HAS BEEN WORKING EAST ACROSS MN IN CONCERT WITH THE IOWA LOW AND HAS HELPED MAINTAIN THE STRATUS NORTH OF THE LOW. BEHIND THIS INVERTED TROUGH...ANOTHER CANADIAN HIGH IS BUILDING SOUTH ACROSS THE DAKOTAS. RH TIME-HEIGHT PROFILES SHOW PLENTY OF DRYING AND SUBSIDENCE OCCURRING AS THIS HIGH MOVES IN...WHICH IS WHY THE QUESTION WITH THE CLOUDS IS HOW LONG DO THEY STICK AROUND. FOR NOW...HAVE A RATHER CLOUDY FORECAST THROUGH 18Z...BUT QUICKLY START TO IMPROVE THINGS FROM WEST TO EAST THIS AFTERNOON...IN LINE WITH WHAT THE RAP 925-850 MB RH SHOWS. ALTHOUGH THERE IS CURRENTLY A SEA OF LIGHT SNOW REPORTS ACROSS NRN MN AND NODAK...THESE ARE NOT EXPECTED TO MAKE IT INTO THE MPX AREA. THE REASON FOR THIS IS THAT SFC TEMPERATURES WHERE THE SNOW IS BEING REPORTED RIGHT NOW ARE ALL IN THE LOW TO MID TEENS...WHICH MEANS UP THERE...THE DENDRITIC GROWTH ZONE IS DOWN AT THE SURFACE AND EXTENDS UP THROUGH THE CLOUD LAYER. ADD IN THE WEAK LIFT ALONG/AHEAD OF THE INVERTED TROUGH WITH A DGZ ALL THE WAY DOWN TO THE SURFACE AND YOU END UP WITH THE SCENARIO WHERE ALL CLOUDS HAVE SNOW. COMING DOWN TO CENTRAL/SRN MN...SFC TEMPS DOWN HERE ARE ALL IN THE UPPER TEENS/LOWER 20S...OUTSIDE OF THE DGZ. THE SHALLOWER DGZ THAT DOES NOT EXTEND TO THE SFC HAS ALLOWED THE CLOUDS DOWN HERE TO REMAIN SNOW FREE. CAA AT THE MOMENT IS NOT STRONG ENOUGH TO COOL OUR SFC TEMPS DOWN INTO THE DGZ BEFORE WE START GETTING SOME SOLAR HEATING...SO DO NOT ANTICIPATE THE SNOW/FLURRY REPORTS TO MAKE IT MUCH FARTHER SOUTH THAN THEY CURRENTLY ARE. THE COMBINATION OF WEAK CAA AND CLOUD COVER WILL AGAIN LIMIT THE DIURNAL TEMPERATURE INCREASE AGAIN TODAY...WITH TEMPERATURES THIS AFTERNOON ONLY EXPECTED TO INCREASE ABOUT 5 OR 10 DEGREES ABOVE THEIR CURRENT VALUES THIS MORNING. TONIGHT...YET ANOTHER SFC RIDGE AXIS WILL BE CENTERED ACROSS THE AREA...RESULTING IN ANOTHER NIGHT WITH LOWS IN THE SINGLE DIGITS TO LOWER TEENS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 250 AM CST THU NOV 28 2013 THE LONG TERM WILL BEGIN TRANQUIL BUT WILL LIKELY END RATHER ACTIVE AS A MAJOR PATTERN SHIFT UNFOLDS. HIGH PRESSURE OVER THE GREAT LAKES WILL SLIDE EAST FRIDAY WITH WAA COMMENCING AT THE START OF THE PERIOD. BREEZY SOUTHEAST WINDS WILL BRING HIGHS BACK TO WHERE THEY SHOULD BE IN THE UPPER 20S TO MID 30S. A WEAK CLIPPER SYSTEM WILL DIVE SOUTHEAST ACROSS NORTHERN LAKE SUPERIOR FRIDAY NIGHT AND EARLY SATURDAY. FORECAST SOUNDINGS SHOW SUFFICIENT MOISTENING IN THE LOWER LEVELS AFTER MIDNIGHT TO SUPPORT A CHANCE OF FREEZING DRIZZLE OR FLURRIES OVER WESTERN WISCONSIN. HOWEVER...KEPT PROBABILITIES RATHER LOW DUE TO THE SOURCE REGION OF THIS MOISTURE BEING FROM THE SPRAWLING EASTERN CONUS HIGH PRESSURE SYSTEM THAT DROVE A COLD FRONT THROUGH THE GULF AND CUBA. NEEDLESS TO SAY...NOT A WHOLE LOT OF MOISTURE TO BE FOUND ANYWHERE NEARBY. SURFACE RIDGING WILL RETURN SATURDAY AND SUNDAY WITH TEMPERATURES REMAINING NEAR NORMAL. MEANWHILE...A POTENT UPPER LOW TRAVERSING ALASKA WILL DIVE SOUTHEAST ALONG THE BRITISH COLOMBIAN COAST INTO THE PACIFIC NORTHWEST AND THE CENTRAL ROCKIES BY THE MIDDLE OF NEXT WEEK. THIS WILL BE REPLACED WITH A 570DM RIDGE OVER ALASKA MONDAY AND BUILDING HEIGHTS ACROSS THE CENTRAL AND EASTERN CONUS FOR LATE WEEK. A SIZABLE CHUNK OF ARCTIC AIR WILL DISLODGE FROM THE POLAR VORTEX AND SINK SOUTH TOWARD THE NORTHERN CONUS BY LATE IN THE LONG TERM. FOLLOWED THE ECMWF/GEM/GFS ENSEMBLE SOLUTION WITH A MORE ZONAL LOOK ACROSS THE NORTHERN TIER OF STATES AS OPPOSED TO THE OPERATIONAL GFS WHICH SEEMED TOO AMPLIFIED DURING MID TO LATE WEEK. SOUTHERLY FLOW AHEAD OF THE WESTERN TROUGH AND MODEST ISENTROPIC LIFT IN THE PRESENCE OF INCREASING MID LEVEL MOISTURE LOOKS INCREASINGLY LIKELY WILL ALLOW FOR PERIODS OF LIGHT SNOW ALONG AN EAST-WEST STATIONARY BOUNDARY FROM SUNDAY NIGHT THROUGH TUESDAY NIGHT. DUE TO A SURFACE HIGH ANCHORED TO THE NORTH...EASTERLY SURFACE FLOW WILL BRING A CONTINUED SUPPLY OF DRY BOUNDARY LAYER AIR AND THUS AMOUNTS WILL BE LIGHT DURING THIS PERIOD. SURFACE LOW ORGANIZING TO THE LEE OF THE ROCKIES IN ADVANCE OF THE ROCKIES TROUGH MAY EJECT NORTHEAST TOWARD THE GREAT LAKES IN THE WEDNESDAY NIGHT/THURSDAY TIMEFRAME. ECMWF BRINGS A PRETTY IMPRESSIVE SYSTEM THROUGH WITH SIGNIFICANT ACCUMULATING SNOW. GEM IS A BIT FURTHER SOUTH. REGARDLESS...FOLLOWING THIS POTENTIAL STORM WILL BE AN EXPANSIVE INTRUSION OF ARCTIC AIR FOR MOST OF THE CENTRAL AND WESTERN CONUS. THIS SIGNAL HAS BEEN SOLID IN CLIMATE FORECASTING MODELS FOR WEEKS NOW AND AS CPC POINTS OUT IN THEIR 6-10 AND 8-14 DAY OUTLOOKS...PROBABILITY OF OCCUR RANCE IS VERY HIGH. IF WE CAN GET A SNOWPACK DOWN BEFORE THIS ARRIVES...TEMPS COULD BE 20-30+ DEGREES BELOW AVERAGE FOR EARLY DECEMBER. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 1025 PM CST WED NOV 27 2013 A BKN-OVC DECK FROM 5KFT-7KFT WILL PREVAIL OVERNIGHT...AS MVFR LEVEL CLOUDS APPROACH FROM THE NORTH/WEST. SAID CLOUDS ARE EXPECTED TO ENTER WEST CENTRAL MN /KAXN/ BY DAYBREAK...AND GRADUALLY SNAKE SOUTH AND EAST /TOWARD KRWF/ DURING THE MORNING. THE CLOUDS SHOULD BECOME MORE TRANSPARENT DURING THE DAYTIME HOWEVER...SO HAVE ONLY INCLUDED A SCATTERED GROUP AT KMSP...BUT KEAU/KRNH LIKELY SEEING BKN-OVC MVFR CIGS THROUGH A GOOD PORTION OF THE DAY. LIGHT AND VARIABLE WINDS OVERNIGHT BECOME WEST/NORTHWEST ON THURSDAY AND INCREASE TO 10-15KTS IN THE WAKE OF THE TROUGH. KMSP... A 5000FT CIG WILL PREVAIL INTO THURSDAY...WITH A POSSIBILITY FOR MVFR LEVEL CLOUDS BETWEEN 18Z THU AND 00Z FRI. HAVE INCLUDED A SCT MENTION FOR NOW. LIGHT AND VARIABLE WINDS OVERNIGHT SHIFT TO THE NORTHWEST BY 14Z THURSDAY /AND GUST TO AROUND 15KTS DURING THE AFTERNOON/. /OUTLOOK FOR KMSP/ FRI...VFR. WINDS SE AT 5-10KTS. SAT...VFR. SW WINDS AT 5-10KTS BECOMING W/NW DURING THE AFT/EVE. SUN...VFR WITH MVFR AND -SN POSSIBLE LATE. WINDS E/SE AT 5KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM...BORGHOFF AVIATION...LS
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1023 PM CST WED NOV 27 2013 .UPDATE...FOR 06Z AVIATION DISCUSSION BELOW && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 215 PM CST WED NOV 27 2013 EARLY AFTERNOON WATER VAPOR IMAGERY TOGETHER WITH GFS 27.12 HEIGHTS AND WINDS IMMEDIATELY IDENTIFIED A LONG WAVE TROUGH ACROSS THE EASTERN CONUS...WITH A CYCLONE DOWNSTREAM OF THIS TROUGH AXIS. NORTHWEST FLOW PREVAILED ACROSS THE CENTRAL CONUS UPSTREAM OF THE TROUGH AXIS. A WEAK SHORTWAVE ALONG THE ND/MN BORDER WAS EMBEDDED IN THIS NORTHWEST FLOW. WARM AIR ADVECTION AHEAD IF THIS SHORTWAVE TOGETHER WITH THE UPPER LEVEL DYNAMICS ASSOCIATED WITH THE 5M/HR HEIGHT FALLS WERE THE DRIVING FORCE BEHIND AN AREA OF SNOW ACROSS NORTHERN MINNESOTA. THIS EVENING THE FORCING WILL WEAKEN...BUT SNOW SHOULD CONTINUE TO SPREAD SOUTHEASTWARD INTO NORTHERN WISCONSIN. THE NORTHEASTERN COUNTIES IN THE CWA WILL BE RIGHT ON THE EDGE OF THIS SNOW...BUT FORECAST SOUNDINGS FOR EAU CLAIRE AND NEW RICHMOND WOULD SUPPORT AT LEAST A FEW HOURS OF SNOW. THE LOW LEVEL DRY AIR WILL DELAY THE ONSET UNTIL CLOSER TO 00Z THIS EVENING. SNOW TOTALS WILL BE LESS THAN AN INCH...AND SHOULD TAPER OFF TO FLURRIES BY THURSDAY MORNING. THE CHALLENGE FOR THURSDAYS FORECAST WAS THE CLOUD COVER. INCREASED IT SLIGHTLY BASED OFF THE 0-1RH FROM BOTH THE NAM AND RAP WHICH SEEM TO HAVE A GOOD HANDLE ON THE STRATUS CURRENTLY ENTERING NORTHERN NORTH DAKOTA. ALSO LOWERED HIGH TEMPS A COUPLE OF DEGREES BECAUSE OF THE INCREASED CLOUD COVER. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 215 PM CST WED NOV 27 2013 BIG CHGS ARE EXPECTED NEXT WEEK AS A SIGNIFICANT ARCTIC AIR MASS SURGES SOUTHWARD ACROSS THE WESTERN CONUS...AND EVENTUALLY TAKING HOLD OF MOST OF THE U.S...WITH THE EXCEPTION IN THE DEEP SE. CURRENT LONG WAVE PATTERN REMAINS FROM THE NW ACROSS THE UPPER MIDWEST ALONG WITH A SPLIT FLOW REGIME FOR THE REMAINDER OF THE CONUS. THE SOUTHERN STREAM HAS BEEN THE MOST ACTIVE IN RECENT WEEKS...TAKING THE BULK OF THE SIGNIFICANT WX TRACKS SOUTH AND EAST OF THE UPPER MIDWEST. ALTHOUGH SOME TIMING AND STRENGTH PARAMETERS REMAIN UNCLEAR IN THE DETERMINISTIC RUNS FROM BOTH THE EC/GFS...THERE REMAINS ONE THEME...A SIGNIFICANT COLD AIR MASS WILL INVADE MOST OF THE U.S. STARTING THIS WEEKEND IN THE PACIFIC NW...AND EVENTUALLY THE ROCKIES/PLAINS/GREAT LAKES BY THE FOLLOWING WEEKEND. USUALLY MODELS ARE TOO FAST ON PATTERN CHGS...AND THIS IS EVIDENT WITH EACH MODEL RUN. ALTHOUGH THE EC HAS BEEN THE STRONGEST ON THE DEEP TROUGH DEVELOPING ACROSS MOST OF THE WESTERN/CENTRAL PART OF THE U.S. BY LATE NEXT WEEK...THE ENSEMBLE MEANS /EC & GFS/ HAVE CONTINUED TO KEEP A MORE PROGRESSIVE WX PATTERN. EVEN THE LATEST EC 12Z/27 RUN HAS A MORE PRONOUNCED DEEP TROUGH ACROSS THE NORTHERN ROCKIES BY THE END OF NEXT WEEK COMPARED TO THE 50H ENSEMBLE MEAN. BASICALLY WITH THE STRONGER AND DEEPER TROUGH...STORM SYSTEMS WILL LIKELY BE SLOWER ON THE ONSET OF SFC LOW /BOMBS/ DEVELOPING ACROSS THE PLAINS. OVER THE PAST 3-5 RUNS OF THE EC...THE SFC LOW AND ASSOCIATED ARCTIC BOUNDARY KEEPS GETTING PUSHED BACK IN TIME ON THE EVOLUTION OF A STRONG STORM SYSTEM IN THE PLAINS. THIS WILL LIKELY KEEP OUR REGION UNEVENTFUL UNTIL LATE IN THE PERIOD...AND POSSIBLY OUTSIDE OUR 7 DAY FORECAST IF THE TROUGH IN THE WEST CONTINUES TO DEEPEN. IN ADDITION TO THE SLOWER PACE OF THE STORM SYSTEM MOVING OUT INTO THE PLAINS...THE LARGE AREA OF ARCTIC HIGH PRESSURE CIRCULATING FROM THE EASTERN CANADA...AND ACROSS THE GREAT LAKES /EAST & NE FLOW IN THE BOUNDARY LAYER/...KEEPS OUR REGION RELATIVELY DRY. THEREFORE...I AM NOT CONFIDENT ON ANY CHC OF PRECIPITATION NEXT WEEK UNTIL THIS SYSTEM MOVES OUT INTO THE PLAINS. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 1025 PM CST WED NOV 27 2013 A BKN-OVC DECK FROM 5KFT-7KFT WILL PREVAIL OVERNIGHT...AS MVFR LEVEL CLOUDS APPROACH FROM THE NORTH/WEST. SAID CLOUDS ARE EXPECTED TO ENTER WEST CENTRAL MN /KAXN/ BY DAYBREAK...AND GRADUALLY SNAKE SOUTH AND EAST /TOWARD KRWF/ DURING THE MORNING. THE CLOUDS SHOULD BECOME MORE TRANSPARENT DURING THE DAYTIME HOWEVER...SO HAVE ONLY INCLUDED A SCATTERED GROUP AT KMSP...BUT KEAU/KRNH LIKELY SEEING BKN-OVC MVFR CIGS THROUGH A GOOD PORTION OF THE DAY. LIGHT AND VARIABLE WINDS OVERNIGHT BECOME WEST/NORTHWEST ON THURSDAY AND INCREASE TO 10-15KTS IN THE WAKE OF THE TROUGH. KMSP... A 5000FT CIG WILL PREVAIL INTO THURSDAY...WITH A POSSIBILITY FOR MVFR LEVEL CLOUDS BETWEEN 18Z THU AND 00Z FRI. HAVE INCLUDED A SCT MENTION FOR NOW. LIGHT AND VARIABLE WINDS OVERNIGHT SHIFT TO THE NORTHWEST BY 14Z THURSDAY /AND GUST TO AROUND 15KTS DURING THE AFTERNOON/. /OUTLOOK FOR KMSP/ FRI...VFR. WINDS SE AT 5-10KTS. SAT...VFR. SW WINDS AT 5-10KTS BECOMING W/NW DURING THE AFT/EVE. SUN...VFR WITH MVFR AND -SN POSSIBLE LATE. WINDS E/SE AT 5KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...JRB LONG TERM...JLT AVIATION...LS
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
554 AM CST Thu Nov 28 2013 .SHORT TERM: (Through Late This Afternoon) Issued at 327 AM CST Thu Nov 28 2013 Southerly winds ahead of low pressure zipping from N IA into MI today will bring a brief shot of warm air into the CWA this morning, which will then be followed by a secondary surge of cold air during the afternoon and into the evening. Primary question for this Thanksgiving Day is how warm to go for high temperatures given the see-saw nature of the temperature advection during the day. Have followed trend of going forecasts in heading towards the warm side of guidance, especially along and south of the I-70 corridor in Missouri where thermal ridge ahead of cold front, mixing, and strong sunshine should all combine to have their greatest impact. In northern sections of the CWA it may be that temps will make a fairly substantial jump this morning, but additional temp climb during the afternoon will struggle as the return of colder air trumps the effects of afternoon sunshine. Have also gone with lots of sunshine today. Will need to keep an eye on post frontal stratus that is making a strong southward surge into E NE early today, but if all of the forecast soundings and RH guidance is to be believed the dry airmass and mixing will cause this deck to erode before reaching our CWA. Truett .LONG TERM: (Tonight through Wednesday) Issued at 327 AM CST Thu Nov 28 2013 (Tonight through Saturday Night) Now that the energy along the East Coast has moved offshore, what is left is a broad low amplitude trough across the ern half of the country and nw flow along the Canadian border funneling into the ern trough. There is split flow along the West Coast with a closed low off the srn CA coast. The NW flow keeps the parade of cold fronts coming every 48 hrs or so with the most recent bndry exiting the CWA early this evening. The next short wave and assoc cold front is fcst for Saturday night. The fronts are passing with such frequency that the atmosphere does not have much chance to recover. Therefore, there isn`t much moisture to work with and the fronts pass quietly with no precip and little to no cloud cover. This front will fail to tap a true arctic airmass and shouldn`t be anymore than a subtle wind shift. There is another short wave that is expected to pass thru the area late this week. The vort max is expected to move across srn MO/IL Friday night into Saturday morning. Due to limited moisture, no precip is expected with this feature. Temps will be slightly cooler on Friday behind the cold front. I generally used a blend of MOS guidance but, tended to favor the warmer MAV. Temps are expected to bounce back again on Saturday in advance of the next cold front. Generally used a blend of guidance but went on the warm side of guidance across cntrl and e cntrl MO due to the synoptic set up for a decent warm up. (Sunday thru Wednesday) Model consensus agrees that NW flow continues thru Monday and then transitions to SW flow by Wednesday. The problem is the path they take from NW to SW flow. Return flow begins Tuesday. The column eventually moistens sufficiently for clouds and rain chances beginning Tuesday night and continuing thru Wednesday. Due to model differences, this is a lower confidence fcst. Highs are expected to be 5-10 degrees cooler on Sunday after the Saturday night FROPA. A slow warming trend begins on Monday that continues thru Wednesday with temps near seasonal norms by Tuesday and Wednesday. 2% && .AVIATION: (For the 12z TAFs through 12z Friday Morning) Issued at 550 AM CST Thu Nov 28 2013 Latest RUC data continues to indicate low level jet over the region early this morning, with southwest winds in the 40-45kt range. LLWS was introduced to the TAFs several hours ago because of this, and will continue the LLWS in the 12z TAFs until 15z when mixing begins to lessen this low level flow. Surface low pressure is allowing warm air to work into the region early today on south-southwest winds, but the cold front trailing the low has now dropped into NW MO. This front will work across the CWA later this afternoon, and 12z TAFs attempt to reflect the wind shift associated with the front. With extremely dry ams forecast in the lower levels of the AMS over the mid-Mississippi Valley, any cloudiness should be limited to some patchy high level cirrus. Will need to keep an eye on stratus dropping across NE and behind the cold front, but all indications are that these clouds will erode before reaching our CWA. Specifics for KSTL: Low level wind shear threat should subside around 15z. Otherwise, it appears favorable flying conditions are in the offing for the KSTL area, with clouds limited to a bit of patchy cirrus. Surface winds will slowly veer to the west during the morning, and then to the northwest this afternoon with the passage of the aforementioned cold front. Truett && .LSX WATCHES/WARNINGS/ADVISORIES: MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1144 AM CST THU NOV 28 2013 .UPDATE... ISSUED AT 913 AM CST THU NOV 28 2013 WITH THICK STRATUS EVIDENT ON SATELLITE IMAGERY AND LATEST RAP COMING IN WITH PESSIMISTIC CONDITIONS FOR THE REST OF THE DAY...WENT AHEAD AND FURTHER INCREASED CLOUD COVER FROM PREVIOUS UPDATE AS WELL AS DROPPED FORECAST HIGH TEMPERATURES ABOUT 5 DEGREES ACROSS THE BOARD. OTHERWISE...NO ADDITIONAL CHANGES NECESSARY AT THIS TIME. UPDATE ISSUED AT 749 AM CST THU NOV 28 2013 BASED ON LATEST SHORTWAVE IR SATELLITE AND MODEL TRENDS... ANTICIPATE WE WILL NEED TO MAKE SOME SUBSTANTIAL CHANGES TO THE FCST TODAY AND POSSIBLY INTO TONIGHT AND TOMORROW. THESE CHANGES WILL INVOLVE MORE CLOUDS AND COOLER TEMPS...PROBABLY NOT BECOMING AS WARM AS THOUGHT THE LAST FEW DAYS AND WE SAW THIS AS A POTENTIAL OPTION EARLIER THIS WEEK. IT/S TOUGH TO FCST FAR IN ADVANCE THOUGH. THERE IS AN EXTENSIVE BANK OF STRATUS RACING S TO THE KS-NEB BORDER AT THIS TIME AND IT EXTENDS ALL THE WAY UP INTO THE CANADIAN PRAIRIES. BELIEVE THIS IS GOING TO BE A FCST PROBLEM THRU SUNSET TOMORROW AS IT WILL BE STUCK IN A THERMAL TROF /COLD POCKET/ AND WILL RESIST EROSION. WE REALLY NEED WARM AIR ADVECTION TO GET RID OF IT AND THAT WILL NOT HAPPEN UNTIL LATE TONIGHT OR TOMORROW. SO THE FCST SKY HAS BEEN TURNED SIGNIFICANTLY MORE PESSIMISTIC THRU MIDDAY AND EXPECT WE WILL NEED TO PUSH THIS FURTHER INTO THE AFTERNOON PENDING THE LATEST SATELLITE TRENDS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 332 AM CST THU NOV 28 2013 OVERNIGHT UPPER AIR ANALYSIS INDICATES MID TO UPPER LEVEL TROUGHING OVER THE EASTERN CONUS...WITH A RIDGE OVER THE WEST AND A MID LEVEL LOW OVER THE PACIFIC OFF THE CALIFORNIA COAST. A SUBTLE MID LEVEL PERTURBATION IS ALSO NOTED OVER SOUTHERN MINNESOTA...MOVING SOUTHEAST. MID TO UPPER LEVEL JET ENERGY EXTENDS FROM SOUTH CENTRAL CANADA...SOUTHEAST INTO THE CENTRAL CONUS...AND FINALLY EAST AND NORTHEAST ALONG THE EASTERN CONUS INTO SOUTHEASTERN CANADA. MID TO UPPER LEVEL FLOW OVER OUR AREA MAXES OUT AT AROUND 70KTS BETWEEN 300MB AND 200MB PER 00Z SOUNDING DATA FROM KLBF AND KOAX. WATER VAPOR IMAGERY INDICATES INCREASED VALUES OF MID LEVEL MOISTURE EXTENDING ALONG THE BACK SIDE OF THE WEST COAST RIDGE...AS WELL AS FROM THE PACIFIC EASTWARD INTO MEXICO AND THE SOUTHERN PLAINS. MID LEVEL MOISTURE OVER OUR AREA HOWEVER REMAINS FAIRLY LIMITED. AT THE SURFACE...AN AREA OF LOW BAROMETRIC PRESSURE EXISTS OVER NORTHWEST IOWA JUST AHEAD OF THE AFOREMENTIONED MID LEVEL PERTURBATION...WITH AN ASSOCIATED COLD FRONT EXTENDING FROM WESTERN IOWA INTO SOUTHEASTERN NEBRASKA AND NORTHERN KANSAS. THIS FRONT HAS CLEARED MOST ALL OF OUR CWA AND AS A RESULT...THE LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE NORTH/NORTHWEST. GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL SUGGEST NORTHWESTERLY MID TO UPPER LEVEL FLOW WILL PERSIST OVER OUR AREA THROUGH THE NEXT 24 HOURS AS THE EASTERN CONUS TROUGH AND WESTERN CONUS RIDGE BOTH TREK EAST. THE MID LEVEL PERTURBATION...CURRENTLY OVER SOUTHERN MINNESOTA...IS EXPECTED TO CONTINUE MOVING SOUTHEAST THROUGH THE NEXT 24 HOURS...WITH NO OTHER MID LEVEL SHORTWAVES/PERTURBATIONS EXPECTED TO IMPACT THE REGION. AT THE SURFACE...THE AREA OF LOW BAROMETRIC PRESSURE...CURRENTLY OVER NORTHWEST IOWA...SHOULD ALSO CONTINUE MOVING TO THE EAST/SOUTHEAST THROUGH THE NEXT 24 HOURS...WITH THE ASSOCIATED LOW LEVEL BAROCLINIC ZONE PUSHING FARTHER SOUTH/SOUTHEAST ACROSS THE PLAINS. THE LOW LEVEL WIND FIELD ACROSS OUR AREA SHOULD REMAIN FROM THE NORTH/NORTHWEST THROUGH MUCH OF TODAY AS A RESULT. THAT BEING SAID...GUIDANCE SUGGESTS THE PASSAGE OF A SURFACE RIDGE TO EAST SHOULD ALLOW FOR LOW LEVEL RETURN FLOW ACROSS OUR AREA DURING THE OVERNIGHT HOURS TONIGHT. WITH AN OVERALL LACK IN OMEGA EXPECTED OVER OUR AREA...DRY CONDITIONS ARE CURRENTLY FORECAST THROUGH THE NEXT 24 HOURS. SATELLITE IMAGERY INDICATES A BAND OF STRATUS OVER MUCH OF THE NORTHERN PLAINS THIS MORNING AND THIS STRATUS IS ADVANCING TO THE SOUTH...ABOUT 150 MILES NORTH OF THE AFOREMENTIONED SURFACE FRONT. GUIDANCE FROM THE NAM AND RAP BOTH SHOW THIS STRATUS...WITH HIGH RELATIVE HUMIDITY VALUES AT 925MB NOTED ON PLAN VIEW MAPS...INFILTRATING OUR NORTH/NORTHEASTERN CWA JUST PRIOR TO SUNRISE THIS MORNING...BUT DISSIPATING POST-SUNRISE AS DIABATIC HEATING RESULTS IN INCREASED BOUNDARY LAYER HEIGHT AND MIXING. WENT AHEAD AND PLAYED PRETTY CLOSE TO NAM AND RAP GUIDANCE FOR THE CLOUD FORECAST THROUGH THE FIRST PART OF THE SHORT TERM FORECAST PERIOD...WITH THIS STRATUS EXPECTED TO IMPACT OUR NORTH/NORTHEAST BY 10Z OR 11Z THIS MORNING...AND THEN DISSIPATE BY 15Z OR 16Z. WITH LOW LEVEL RETURN FLOW INFILTRATING THE REGION TONIGHT...THERE ARE INDICATIONS OF ISENTROPIC UPGLIDE AND SATURATION...PRIMARILY ALONG THE 275-285K SURFACES...OVER THE HIGH PLAINS OF KANSAS AND NEBRASKA. ALTHOUGH IT APPEARS MUCH OF OUR CWA SHOULD BE SPARED FROM ANY STRATUS DEVELOPMENT THROUGH 12Z FRIDAY...925MB RELATIVE HUMIDITY PLAN VIEW MAPS FROM THE NAM...OPERATIONAL GFS AND EC ALL SUGGEST OUR EXTREME WEST/SOUTHWEST COULD ACTUALLY OBSERVE QUITE A BIT OF CLOUD COVER TOWARDS SUNRISE FRIDAY AS THE EASTERN PERIPHERY OF THE HIGH PLAINS STRATUS CLIPS THE AREA. WENT AHEAD WITH A BROKEN CEILING ACROSS OUR EXTREME WEST/SOUTHWEST BY 12Z FRIDAY AS A RESULT. THE INTRUSION OF A COOLER LOW LEVEL AIRMASS BEHIND THE LOW LEVEL BAROCLINIC ZONE SHOULD RESULT IN A COOLER DAY TODAY WHEN COMPARED TO WEDNESDAY. HIGH TEMPERATURES GENERALLY IN THE MID 30S ACROSS OUR NORTH...AND INTO THE MID 40S ACROSS OUR SOUTH...ARE FORECAST FOR TODAY AS A RESULT. IT MIGHT OTHERWISE BE REASONABLE TO THINK TONIGHT WILL BE COOLER WHEN COMPARED TO EARLY THIS MORNING...BUT WITH LOW LEVEL RETURN FLOW EXPECTED TO INFILTRATE OUR AREA DURING THE OVERNIGHT HOURS...OVERNIGHT LOWS TONIGHT SHOULD ACTUALLY BE PRETTY CLOSE TO WHAT WE ARE EXPECTING EARLY THIS MORNING. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 332 AM CST THU NOV 28 2013 THE FIRST PART OF THE LONG TERM FORECAST IS DRY WITH ABOVE NORMAL TEMPERATURES...AFTER WHICH A MORE UNSETTLED...COLDER AND MORE CHALLENGING FORECAST TAKES HOLD BY MID NEXT WEEK. A TRANSITIONING WEST/NORTHWEST UPPER LEVEL FLOW WILL KEEP THE REGION MAINLY DRY AND MILD THROUGH THROUGH THE REMAINDER OF THE HOLIDAY WEEKEND. REGIONAL TRAVEL CONCERNS WILL BE NIL...AND BOTH DAYTIME HIGHS AND NIGHTTIME LOWS WILL BE AT OR SLIGHTLY ABOVE SEASONAL NORMALS. ONE NOTABLE WEATHER ELEMENT WILL THE WIND...OR LACK THERE OF ON SATURDAY AND SUNDAY. THAT WILL HELP OFFSET ANY COOLING FROM PASSING CLOUDS THROUGHOUT THE WEEKEND. OVERALL...PRETTY NICE FOR THE END OF NOVEMBER. WARM ADVECTION ASSOCIATED WITH WAVE ACROSS THE NORTHERN PLAINS SUNDAY WILL THICKEN CLOUDS...BUT NOT TOO EXCITED ABOUT INCURRING ANY MEASURABLE PRECIPITATION AT THIS POINT. ACTUALLY THE MILD WEATHER WILL CONTINUE INTO THE FIRST PART OF NEXT WEEK...ALTHOUGH THINGS WILL BE CHANGING AS UPPER LEVEL HEIGHTS LOWER AND WE START TO SEE UPPER LEVEL LOW PRESSURE DEEPEN IN THE GREAT BASIN REGION. AS THE LOW STRENGTHENS...AN INCREASING SOUTH TO SOUTHEAST FLOW ACROSS THE CENTRAL/SOUTHERN PLAINS DEVELOPS WHICH WILL KEEP TEMPERATURES ON THE MILD SIDE MONDAY/TUESDAY. THERE IS SOME MODEL LIKENESS IN OVERALL TRENDS...BUT VERY UNEASY IN TRYING TO PIN DOWN ANY SPECIFIC DETAILS FOR NEXT WEEKS FORECAST AT THIS POINT. WE HAVE BEEN ANTICIPATING A COLD AIR PUSH NEXT WEEK...AND THAT STILL LOOKS ON TRACK FOR ABOUT WEDNESDAY...BUT THE COLD AIR PLUNGE COMES IN PIECES WITH THE COLDEST AIR NOT LIKELY TO MAKE IT INTO THE AREA UNTIL LATER NEXT WEEK. MODELS SUGGEST HEAVIEST PRECIPITATION TRENDS WILL LIKELY BE ACROSS THE DAKOTAS AT THIS POINT...WITH ONLY SMALL CHANCES FOR RAIN OR RAIN/SNOW MIX IN THE FORECAST AT THIS POINT AS THE SYSTEM APPROACHES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1140 AM CST THU NOV 28 2013 A BREAK IN MVFR STRATUS IS EVIDENT ON LATEST SATELLITE IMAGERY...BUT EXPECT THIS STRATUS TO RAPIDLY FILL BACK IN BY ABOUT 28/20Z...AND PERSIST THROUGH THE LATE AFTERNOON OR EARLY EVENING HOURS. WINDS WILL GENERALLY REMAIN NORTHERLY THROUGH THE AFTERNOON HOURS...EVENTUALLY BECOMING LIGHT AND VARIABLE AS THE SURFACE HIGH TRACKS SOUTH ACROSS THE MISSOURI RIVER VALLEY. SOUTHERLY WINDS ARE EXPECTED TO INCREASE IN RETURN FLOW AROUND THIS HIGH PRESSURE SYSTEM ON FRIDAY. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...ROSSI SHORT TERM...NOAA/NWS/BRYANT LONG TERM...NOAA/NWS/MORITZ AVIATION...ROSSI
AREA FORECAST DISCUSSION
NWS HASTINGS NE
919 AM CST THU NOV 28 2013 .UPDATE... ISSUED AT 913 AM CST THU NOV 28 2013 WITH THICK STRATUS EVIDENT ON SATELLITE IMAGERY AND LATEST RAP COMING IN WITH PESSIMISTIC CONDITIONS FOR THE REST OF THE DAY...WENT AHEAD AND FURTHER INCREASED CLOUD COVER FROM PREVIOUS UPDATE AS WELL AS DROPPED FORECAST HIGH TEMPERATURES ABOUT 5 DEGREES ACROSS THE BOARD. OTHERWISE...NO ADDITIONAL CHANGES NECESSARY AT THIS TIME. UPDATE ISSUED AT 749 AM CST THU NOV 28 2013 BASED ON LATEST SHORTWAVE IR SATELLITE AND MODEL TRENDS... ANTICIPATE WE WILL NEED TO MAKE SOME SUBSTANTIAL CHANGES TO THE FCST TODAY AND POSSIBLY INTO TONIGHT AND TOMORROW. THESE CHANGES WILL INVOLVE MORE CLOUDS AND COOLER TEMPS...PROBABLY NOT BECOMING AS WARM AS THOUGHT THE LAST FEW DAYS AND WE SAW THIS AS A POTENTIAL OPTION EARLIER THIS WEEK. IT/S TOUGH TO FCST FAR IN ADVANCE THOUGH. THERE IS AN EXTENSIVE BANK OF STRATUS RACING S TO THE KS-NEB BORDER AT THIS TIME AND IT EXTENDS ALL THE WAY UP INTO THE CANADIAN PRAIRIES. BELIEVE THIS IS GOING TO BE A FCST PROBLEM THRU SUNSET TOMORROW AS IT WILL BE STUCK IN A THERMAL TROF /COLD POCKET/ AND WILL RESIST EROSION. WE REALLY NEED WARM AIR ADVECTION TO GET RID OF IT AND THAT WILL NOT HAPPEN UNTIL LATE TONIGHT OR TOMORROW. SO THE FCST SKY HAS BEEN TURNED SIGNIFICANTLY MORE PESSIMISTIC THRU MIDDAY AND EXPECT WE WILL NEED TO PUSH THIS FURTHER INTO THE AFTERNOON PENDING THE LATEST SATELLITE TRENDS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 332 AM CST THU NOV 28 2013 OVERNIGHT UPPER AIR ANALYSIS INDICATES MID TO UPPER LEVEL TROUGHING OVER THE EASTERN CONUS...WITH A RIDGE OVER THE WEST AND A MID LEVEL LOW OVER THE PACIFIC OFF THE CALIFORNIA COAST. A SUBTLE MID LEVEL PERTURBATION IS ALSO NOTED OVER SOUTHERN MINNESOTA...MOVING SOUTHEAST. MID TO UPPER LEVEL JET ENERGY EXTENDS FROM SOUTH CENTRAL CANADA...SOUTHEAST INTO THE CENTRAL CONUS...AND FINALLY EAST AND NORTHEAST ALONG THE EASTERN CONUS INTO SOUTHEASTERN CANADA. MID TO UPPER LEVEL FLOW OVER OUR AREA MAXES OUT AT AROUND 70KTS BETWEEN 300MB AND 200MB PER 00Z SOUNDING DATA FROM KLBF AND KOAX. WATER VAPOR IMAGERY INDICATES INCREASED VALUES OF MID LEVEL MOISTURE EXTENDING ALONG THE BACK SIDE OF THE WEST COAST RIDGE...AS WELL AS FROM THE PACIFIC EASTWARD INTO MEXICO AND THE SOUTHERN PLAINS. MID LEVEL MOISTURE OVER OUR AREA HOWEVER REMAINS FAIRLY LIMITED. AT THE SURFACE...AN AREA OF LOW BAROMETRIC PRESSURE EXISTS OVER NORTHWEST IOWA JUST AHEAD OF THE AFOREMENTIONED MID LEVEL PERTURBATION...WITH AN ASSOCIATED COLD FRONT EXTENDING FROM WESTERN IOWA INTO SOUTHEASTERN NEBRASKA AND NORTHERN KANSAS. THIS FRONT HAS CLEARED MOST ALL OF OUR CWA AND AS A RESULT...THE LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE NORTH/NORTHWEST. GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL SUGGEST NORTHWESTERLY MID TO UPPER LEVEL FLOW WILL PERSIST OVER OUR AREA THROUGH THE NEXT 24 HOURS AS THE EASTERN CONUS TROUGH AND WESTERN CONUS RIDGE BOTH TREK EAST. THE MID LEVEL PERTURBATION...CURRENTLY OVER SOUTHERN MINNESOTA...IS EXPECTED TO CONTINUE MOVING SOUTHEAST THROUGH THE NEXT 24 HOURS...WITH NO OTHER MID LEVEL SHORTWAVES/PERTURBATIONS EXPECTED TO IMPACT THE REGION. AT THE SURFACE...THE AREA OF LOW BAROMETRIC PRESSURE...CURRENTLY OVER NORTHWEST IOWA...SHOULD ALSO CONTINUE MOVING TO THE EAST/SOUTHEAST THROUGH THE NEXT 24 HOURS...WITH THE ASSOCIATED LOW LEVEL BAROCLINIC ZONE PUSHING FARTHER SOUTH/SOUTHEAST ACROSS THE PLAINS. THE LOW LEVEL WIND FIELD ACROSS OUR AREA SHOULD REMAIN FROM THE NORTH/NORTHWEST THROUGH MUCH OF TODAY AS A RESULT. THAT BEING SAID...GUIDANCE SUGGESTS THE PASSAGE OF A SURFACE RIDGE TO EAST SHOULD ALLOW FOR LOW LEVEL RETURN FLOW ACROSS OUR AREA DURING THE OVERNIGHT HOURS TONIGHT. WITH AN OVERALL LACK IN OMEGA EXPECTED OVER OUR AREA...DRY CONDITIONS ARE CURRENTLY FORECAST THROUGH THE NEXT 24 HOURS. SATELLITE IMAGERY INDICATES A BAND OF STRATUS OVER MUCH OF THE NORTHERN PLAINS THIS MORNING AND THIS STRATUS IS ADVANCING TO THE SOUTH...ABOUT 150 MILES NORTH OF THE AFOREMENTIONED SURFACE FRONT. GUIDANCE FROM THE NAM AND RAP BOTH SHOW THIS STRATUS...WITH HIGH RELATIVE HUMIDITY VALUES AT 925MB NOTED ON PLAN VIEW MAPS...INFILTRATING OUR NORTH/NORTHEASTERN CWA JUST PRIOR TO SUNRISE THIS MORNING...BUT DISSIPATING POST-SUNRISE AS DIABATIC HEATING RESULTS IN INCREASED BOUNDARY LAYER HEIGHT AND MIXING. WENT AHEAD AND PLAYED PRETTY CLOSE TO NAM AND RAP GUIDANCE FOR THE CLOUD FORECAST THROUGH THE FIRST PART OF THE SHORT TERM FORECAST PERIOD...WITH THIS STRATUS EXPECTED TO IMPACT OUR NORTH/NORTHEAST BY 10Z OR 11Z THIS MORNING...AND THEN DISSIPATE BY 15Z OR 16Z. WITH LOW LEVEL RETURN FLOW INFILTRATING THE REGION TONIGHT...THERE ARE INDICATIONS OF ISENTROPIC UPGLIDE AND SATURATION...PRIMARILY ALONG THE 275-285K SURFACES...OVER THE HIGH PLAINS OF KANSAS AND NEBRASKA. ALTHOUGH IT APPEARS MUCH OF OUR CWA SHOULD BE SPARED FROM ANY STRATUS DEVELOPMENT THROUGH 12Z FRIDAY...925MB RELATIVE HUMIDITY PLAN VIEW MAPS FROM THE NAM...OPERATIONAL GFS AND EC ALL SUGGEST OUR EXTREME WEST/SOUTHWEST COULD ACTUALLY OBSERVE QUITE A BIT OF CLOUD COVER TOWARDS SUNRISE FRIDAY AS THE EASTERN PERIPHERY OF THE HIGH PLAINS STRATUS CLIPS THE AREA. WENT AHEAD WITH A BROKEN CEILING ACROSS OUR EXTREME WEST/SOUTHWEST BY 12Z FRIDAY AS A RESULT. THE INTRUSION OF A COOLER LOW LEVEL AIRMASS BEHIND THE LOW LEVEL BAROCLINIC ZONE SHOULD RESULT IN A COOLER DAY TODAY WHEN COMPARED TO WEDNESDAY. HIGH TEMPERATURES GENERALLY IN THE MID 30S ACROSS OUR NORTH...AND INTO THE MID 40S ACROSS OUR SOUTH...ARE FORECAST FOR TODAY AS A RESULT. IT MIGHT OTHERWISE BE REASONABLE TO THINK TONIGHT WILL BE COOLER WHEN COMPARED TO EARLY THIS MORNING...BUT WITH LOW LEVEL RETURN FLOW EXPECTED TO INFILTRATE OUR AREA DURING THE OVERNIGHT HOURS...OVERNIGHT LOWS TONIGHT SHOULD ACTUALLY BE PRETTY CLOSE TO WHAT WE ARE EXPECTING EARLY THIS MORNING. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 332 AM CST THU NOV 28 2013 THE FIRST PART OF THE LONG TERM FORECAST IS DRY WITH ABOVE NORMAL TEMPERATURES...AFTERWHICH A MORE UNSETTLED...COLDER AND MORE CHALLENGING FORECAST TAKES HOLD BY MID NEXT WEEK. A TRANSITIONING WEST/NORTHWEST UPPER LEVEL FLOW WILL KEEP THE REGION MAINLY DRY AND MILD THROUGH THROUGH THE REMAINDER OF THE HOLIDAY WEEKEND. REGIONAL TRAVEL CONCERNS WILL BE NIL...AND BOTH DAYTIME HIGHS AND NIGHTTIME LOWS WILL BE AT OR SLIGHTLY ABOVE SEASONAL NORMALS. ONE NOTABLE WEATHER ELEMENT WILL THE WIND...OR LACK THERE OF ON SATURDAY AND SUNDAY. THAT WILL HELP OFFSET ANY COOLING FROM PASSING CLOUDS THROUGHOUT THE WEEKEND. OVERALL...PRETTY NICE FOR THE END OF NOVEMBER. WARM ADVECTION ASSOCIATED WITH WAVE ACROSS THE NORTHERN PLAINS SUNDAY WILL THICKEN CLOUDS...BUT NOT TOO EXCITED ABOUT INCURRING ANY MEASURABLE PRECIPITATION AT THIS POINT. ACTUALLY THE MILD WEATHER WILL CONTINUE INTO THE FIRST PART OF NEXT WEEK...ALTHOUGH THINGS WILL BE CHANGING AS UPPER LEVEL HEIGHTS LOWER AND WE START TO SEE UPPER LEVEL LOW PRESSURE DEEPEN IN THE GREAT BASIN REGION. AS THE LOW STRENGTHENS...AN INCREASING SOUTH TO SOUTHEAST FLOW ACROSS THE CENTRAL/SOUTHERN PLAINS DEVELOPS WHICH WILL KEEP TEMPERATURES ON THE MILD SIDE MONDAY/TUESDAY. THERE IS SOME MODEL LIKENESS IN OVERALL TRENDS...BUT VERY UNEASY IN TRYING TO PIN DOWN ANY SPECIFIC DETAILS FOR NEXT WEEKS FORECAST AT THIS POINT. WE HAVE BEEN ANTICIPATING A COLD AIR PUSH NEXT WEEK...AND THAT STILL LOOKS ON TRACK FOR ABOUT WEDNESDAY...BUT THE COLD AIR PLUNGE COMES IN PIECES WITH THE COLDEST AIR NOT LIKELY TO MAKE IT INTO THE AREA UNTIL LATER NEXT WEEK. MODELS SUGGEST HEAVIEST PRECIPITATION TRENDS WILL LIKELY BE ACROSS THE DAKOTAS AT THIS POINT...WITH ONLY SMALL CHANCES FOR RAIN OR RAIN/SNOW MIX IN THE FORECAST AT THIS POINT AS THE SYSTEM APPROACHES. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 530 AM CST THU NOV 28 2013 MVFR CONDITIONS EXPECTED TO START THE TAF PERIOD...WITH VFR CONDITIONS EXPECTED 15Z AND BEYOND. AN AREA OF STRATUS HAS BEEN MOVING SOUTH FROM SOUTH DAKOTA ALL NIGHT AND IS NOW MOVING INTO THE GRI AREA. THE CEILING WITHIN THIS STRATUS GENERALLY RANGES BETWEEN 1000FT AND 1500FT AGL...THUS THE MVFR FORECAST 12-15Z. GUIDANCE CONTINUES TO SUGGEST THIS STRATUS WILL LIFT AND BREAK APART AFTER SUNRISE AS INCREASING DIABATIC HEATING ALLOWS FOR INCREASING BOUNDARY LAYER DEPTH AND MIXING. VFR CONDITIONS ARE CURRENTLY EXPECTED TO BE RESTORED BY 15Z...BUT THIS WILL NEED TO BE MONITORED THROUGH THE NEXT FEW HOURS FOR POSSIBLE UPDATES TO THE TAF. THE SURFACE WIND WILL REMAIN FROM THE NORTH/NORTHEAST TODAY...SUSTAINED AT AROUND 10KTS. THE PASSAGE OF A SURFACE RIDGE WILL THEN ALLOW FOR A WEAK...NO GREATER THAN 6KTS...SOUTHEASTERLY LOW LEVEL WIND FIELD OVERNIGHT TONIGHT. VISIBILITY RESTRICTION IS NOT EXPECTED AT GRI THROUGH THE NEXT 24 HOURS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...ROSSI SHORT TERM...NOAA/NWS/BRYANT LONG TERM...NOAA/NWS/MORITZ AVIATION...NOAA/NWS/BRYANT
AREA FORECAST DISCUSSION
NWS HASTINGS NE
749 AM CST THU NOV 28 2013 .UPDATE... ISSUED AT 749 AM CST THU NOV 28 2013 BASED ON LATEST SHORTWAVE IR SATELLITE AND MODEL TRENDS... ANTICIPATE WE WILL NEED TO MAKE SOME SUBSTANTIAL CHANGES TO THE FCST TODAY AND POSSIBLY INTO TONIGHT AND TOMORROW. THESE CHANGES WILL INVOLVE MORE CLOUDS AND COOLER TEMPS...PROBABLY NOT BECOMING AS WARM AS THOUGHT THE LAST FEW DAYS AND WE SAW THIS AS A POTENTIAL OPTION EARLIER THIS WEEK. IT/S TOUGH TO FCST FAR IN ADVANCE THOUGH. THERE IS AN EXTENSIVE BANK OF STRATUS RACING S TO THE KS-NEB BORDER AT THIS TIME AND IT EXTENDS ALL THE WAY UP INTO THE CANADIAN PRAIRIES. BELIEVE THIS IS GOING TO BE A FCST PROBLEM THRU SUNSET TOMORROW AS IT WILL BE STUCK IN A THERMAL TROF /COLD POCKET/ AND WILL RESIST EROSION. WE REALLY NEED WARM AIR ADVECTION TO GET RID OF IT AND THAT WILL NOT HAPPEN UNTIL LATE TONIGHT OR TOMORROW. SO THE FCST SKY HAS BEEN TURNED SIGNIFICANTLY MORE PESSIMISTIC THRU MIDDAY AND EXPECT WE WILL NEED TO PUSH THIS FURTHER INTO THE AFTERNOON PENDING THE LATEST SATELLITE TRENDS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 332 AM CST THU NOV 28 2013 OVERNIGHT UPPER AIR ANALYSIS INDICATES MID TO UPPER LEVEL TROUGHING OVER THE EASTERN CONUS...WITH A RIDGE OVER THE WEST AND A MID LEVEL LOW OVER THE PACIFIC OFF THE CALIFORNIA COAST. A SUBTLE MID LEVEL PERTURBATION IS ALSO NOTED OVER SOUTHERN MINNESOTA...MOVING SOUTHEAST. MID TO UPPER LEVEL JET ENERGY EXTENDS FROM SOUTH CENTRAL CANADA...SOUTHEAST INTO THE CENTRAL CONUS...AND FINALLY EAST AND NORTHEAST ALONG THE EASTERN CONUS INTO SOUTHEASTERN CANADA. MID TO UPPER LEVEL FLOW OVER OUR AREA MAXES OUT AT AROUND 70KTS BETWEEN 300MB AND 200MB PER 00Z SOUNDING DATA FROM KLBF AND KOAX. WATER VAPOR IMAGERY INDICATES INCREASED VALUES OF MID LEVEL MOISTURE EXTENDING ALONG THE BACK SIDE OF THE WEST COAST RIDGE...AS WELL AS FROM THE PACIFIC EASTWARD INTO MEXICO AND THE SOUTHERN PLAINS. MID LEVEL MOISTURE OVER OUR AREA HOWEVER REMAINS FAIRLY LIMITED. AT THE SURFACE...AN AREA OF LOW BAROMETRIC PRESSURE EXISTS OVER NORTHWEST IOWA JUST AHEAD OF THE AFOREMENTIONED MID LEVEL PERTURBATION...WITH AN ASSOCIATED COLD FRONT EXTENDING FROM WESTERN IOWA INTO SOUTHEASTERN NEBRASKA AND NORTHERN KANSAS. THIS FRONT HAS CLEARED MOST ALL OF OUR CWA AND AS A RESULT...THE LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE NORTH/NORTHWEST. GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL SUGGEST NORTHWESTERLY MID TO UPPER LEVEL FLOW WILL PERSIST OVER OUR AREA THROUGH THE NEXT 24 HOURS AS THE EASTERN CONUS TROUGH AND WESTERN CONUS RIDGE BOTH TREK EAST. THE MID LEVEL PERTURBATION...CURRENTLY OVER SOUTHERN MINNESOTA...IS EXPECTED TO CONTINUE MOVING SOUTHEAST THROUGH THE NEXT 24 HOURS...WITH NO OTHER MID LEVEL SHORTWAVES/PERTURBATIONS EXPECTED TO IMPACT THE REGION. AT THE SURFACE...THE AREA OF LOW BAROMETRIC PRESSURE...CURRENTLY OVER NORTHWEST IOWA...SHOULD ALSO CONTINUE MOVING TO THE EAST/SOUTHEAST THROUGH THE NEXT 24 HOURS...WITH THE ASSOCIATED LOW LEVEL BAROCLINIC ZONE PUSHING FARTHER SOUTH/SOUTHEAST ACROSS THE PLAINS. THE LOW LEVEL WIND FIELD ACROSS OUR AREA SHOULD REMAIN FROM THE NORTH/NORTHWEST THROUGH MUCH OF TODAY AS A RESULT. THAT BEING SAID...GUIDANCE SUGGESTS THE PASSAGE OF A SURFACE RIDGE TO EAST SHOULD ALLOW FOR LOW LEVEL RETURN FLOW ACROSS OUR AREA DURING THE OVERNIGHT HOURS TONIGHT. WITH AN OVERALL LACK IN OMEGA EXPECTED OVER OUR AREA...DRY CONDITIONS ARE CURRENTLY FORECAST THROUGH THE NEXT 24 HOURS. SATELLITE IMAGERY INDICATES A BAND OF STRATUS OVER MUCH OF THE NORTHERN PLAINS THIS MORNING AND THIS STRATUS IS ADVANCING TO THE SOUTH...ABOUT 150 MILES NORTH OF THE AFOREMENTIONED SURFACE FRONT. GUIDANCE FROM THE NAM AND RAP BOTH SHOW THIS STRATUS...WITH HIGH RELATIVE HUMIDITY VALUES AT 925MB NOTED ON PLAN VIEW MAPS...INFILTRATING OUR NORTH/NORTHEASTERN CWA JUST PRIOR TO SUNRISE THIS MORNING...BUT DISSIPATING POST-SUNRISE AS DIABATIC HEATING RESULTS IN INCREASED BOUNDARY LAYER HEIGHT AND MIXING. WENT AHEAD AND PLAYED PRETTY CLOSE TO NAM AND RAP GUIDANCE FOR THE CLOUD FORECAST THROUGH THE FIRST PART OF THE SHORT TERM FORECAST PERIOD...WITH THIS STRATUS EXPECTED TO IMPACT OUR NORTH/NORTHEAST BY 10Z OR 11Z THIS MORNING...AND THEN DISSIPATE BY 15Z OR 16Z. WITH LOW LEVEL RETURN FLOW INFILTRATING THE REGION TONIGHT...THERE ARE INDICATIONS OF ISENTROPIC UPGLIDE AND SATURATION...PRIMARILY ALONG THE 275-285K SURFACES...OVER THE HIGH PLAINS OF KANSAS AND NEBRASKA. ALTHOUGH IT APPEARS MUCH OF OUR CWA SHOULD BE SPARED FROM ANY STRATUS DEVELOPMENT THROUGH 12Z FRIDAY...925MB RELATIVE HUMIDITY PLAN VIEW MAPS FROM THE NAM...OPERATIONAL GFS AND EC ALL SUGGEST OUR EXTREME WEST/SOUTHWEST COULD ACTUALLY OBSERVE QUITE A BIT OF CLOUD COVER TOWARDS SUNRISE FRIDAY AS THE EASTERN PERIPHERY OF THE HIGH PLAINS STRATUS CLIPS THE AREA. WENT AHEAD WITH A BROKEN CEILING ACROSS OUR EXTREME WEST/SOUTHWEST BY 12Z FRIDAY AS A RESULT. THE INTRUSION OF A COOLER LOW LEVEL AIRMASS BEHIND THE LOW LEVEL BAROCLINIC ZONE SHOULD RESULT IN A COOLER DAY TODAY WHEN COMPARED TO WEDNESDAY. HIGH TEMPERATURES GENERALLY IN THE MID 30S ACROSS OUR NORTH...AND INTO THE MID 40S ACROSS OUR SOUTH...ARE FORECAST FOR TODAY AS A RESULT. IT MIGHT OTHERWISE BE REASONABLE TO THINK TONIGHT WILL BE COOLER WHEN COMPARED TO EARLY THIS MORNING...BUT WITH LOW LEVEL RETURN FLOW EXPECTED TO INFILTRATE OUR AREA DURING THE OVERNIGHT HOURS...OVERNIGHT LOWS TONIGHT SHOULD ACTUALLY BE PRETTY CLOSE TO WHAT WE ARE EXPECTING EARLY THIS MORNING. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 332 AM CST THU NOV 28 2013 THE FIRST PART OF THE LONG TERM FORECAST IS DRY WITH ABOVE NORMAL TEMPERATURES...AFTERWHICH A MORE UNSETTLED...COLDER AND MORE CHALLENGING FORECAST TAKES HOLD BY MID NEXT WEEK. A TRANSITIONING WEST/NORTHWEST UPPER LEVEL FLOW WILL KEEP THE REGION MAINLY DRY AND MILD THROUGH THROUGH THE REMAINDER OF THE HOLIDAY WEEKEND. REGIONAL TRAVEL CONCERNS WILL BE NIL...AND BOTH DAYTIME HIGHS AND NIGHTTIME LOWS WILL BE AT OR SLIGHTLY ABOVE SEASONAL NORMALS. ONE NOTABLE WEATHER ELEMENT WILL THE WIND...OR LACK THERE OF ON SATURDAY AND SUNDAY. THAT WILL HELP OFFSET ANY COOLING FROM PASSING CLOUDS THROUGHOUT THE WEEKEND. OVERALL...PRETTY NICE FOR THE END OF NOVEMBER. WARM ADVECTION ASSOCIATED WITH WAVE ACROSS THE NORTHERN PLAINS SUNDAY WILL THICKEN CLOUDS...BUT NOT TOO EXCITED ABOUT INCURRING ANY MEASURABLE PRECIPITATION AT THIS POINT. ACTUALLY THE MILD WEATHER WILL CONTINUE INTO THE FIRST PART OF NEXT WEEK...ALTHOUGH THINGS WILL BE CHANGING AS UPPER LEVEL HEIGHTS LOWER AND WE START TO SEE UPPER LEVEL LOW PRESSURE DEEPEN IN THE GREAT BASIN REGION. AS THE LOW STRENGTHENS...AN INCREASING SOUTH TO SOUTHEAST FLOW ACROSS THE CENTRAL/SOUTHERN PLAINS DEVELOPS WHICH WILL KEEP TEMPERATURES ON THE MILD SIDE MONDAY/TUESDAY. THERE IS SOME MODEL LIKENESS IN OVERALL TRENDS...BUT VERY UNEASY IN TRYING TO PIN DOWN ANY SPECIFIC DETAILS FOR NEXT WEEKS FORECAST AT THIS POINT. WE HAVE BEEN ANTICIPATING A COLD AIR PUSH NEXT WEEK...AND THAT STILL LOOKS ON TRACK FOR ABOUT WEDNESDAY...BUT THE COLD AIR PLUNGE COMES IN PIECES WITH THE COLDEST AIR NOT LIKELY TO MAKE IT INTO THE AREA UNTIL LATER NEXT WEEK. MODELS SUGGEST HEAVIEST PRECIPITATION TRENDS WILL LIKELY BE ACROSS THE DAKOTAS AT THIS POINT...WITH ONLY SMALL CHANCES FOR RAIN OR RAIN/SNOW MIX IN THE FORECAST AT THIS POINT AS THE SYSTEM APPROACHES. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 530 AM CST THU NOV 28 2013 MVFR CONDITIONS EXPECTED TO START THE TAF PERIOD...WITH VFR CONDITIONS EXPECTED 15Z AND BEYOND. AN AREA OF STRATUS HAS BEEN MOVING SOUTH FROM SOUTH DAKOTA ALL NIGHT AND IS NOW MOVING INTO THE GRI AREA. THE CEILING WITHIN THIS STRATUS GENERALLY RANGES BETWEEN 1000FT AND 1500FT AGL...THUS THE MVFR FORECAST 12-15Z. GUIDANCE CONTINUES TO SUGGEST THIS STRATUS WILL LIFT AND BREAK APART AFTER SUNRISE AS INCREASING DIABATIC HEATING ALLOWS FOR INCREASING BOUNDARY LAYER DEPTH AND MIXING. VFR CONDITIONS ARE CURRENTLY EXPECTED TO BE RESTORED BY 15Z...BUT THIS WILL NEED TO BE MONITORED THROUGH THE NEXT FEW HOURS FOR POSSIBLE UPDATES TO THE TAF. THE SURFACE WIND WILL REMAIN FROM THE NORTH/NORTHEAST TODAY...SUSTAINED AT AROUND 10KTS. THE PASSAGE OF A SURFACE RIDGE WILL THEN ALLOW FOR A WEAK...NO GREATER THAN 6KTS...SOUTHEASTERLY LOW LEVEL WIND FIELD OVERNIGHT TONIGHT. VISIBILITY RESTRICTION IS NOT EXPECTED AT GRI THROUGH THE NEXT 24 HOURS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...HALBLAUB SHORT TERM...NOAA/NWS/BRYANT LONG TERM...NOAA/NWS/MORITZ AVIATION...NOAA/NWS/BRYANT
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
548 AM CST THU NOV 28 2013 .AVIATION... 12Z TAFS FOR KOMA...KOFK...KLNK THE MAIN INITIAL ISSUE IS THE MVFR STRATUS DECK THAT HAS MOVED INTO KOFK AND IS APPROACHING KOMA/KLNK. THE MODELS ARE NOT HANDLING THIS DECK WELL WITH THE RUC13 LIKELY DOING THE BEST. LATEST SAT IMAGERY INDICATES THE CLOUDS EWD PROGRESS HAS SLOWED AND THIS IS INDICATED IN MOST MODELS THROUGH THE MORNING. THUS WE WILL LEAVE THE DECK OUT OF KOMA FOR NOW...AND ALTHOUGH THE SWD MOVEMENT HAS ALSO SLOWED WE WILL INCLUDE A TEMPO MVFR GROUP THIS MORNING FOR A TIME AS THE CLOUDS ARE MORE LIKELY TO MAKE IT THERE GIVEN THE 925 MB WINDS. OTHERWISE THE MVFR CLOUDS WILL SLOWLY DISSIPATE THIS AFTERNOON AT KOFK...AND ONCE THIS OCCURS VFR CONDITIONS ARE EXPECTED FOR THE REST OF THE PERIOD AT ALL SITES. WINDS WILL START TO DIMINISH THIS AFTN AND WILL GO LIGHT OVERNIGHT. BOUSTEAD && .PREV DISCUSSION... /ISSUED 329 AM CST THU NOV 28 2013/ DISCUSSION... WATER VAPOR IMAGERY THIS MORNING SHOWING A DISTINCT CLOSED LOW SPINNING JUST OFF THE WEST COAST ALONG WITH A WELL AMPLIFIED RIDGE OVER THE WRN CONUS EXTENDING ALL THE WAY UP THE CANADIAN WEST COAST. MEANWHILE BROAD DOWNSTREAM TROF WAS SITUATED OVER THE ERN CONUS. HAVE OPTED TO MAKE SOME POP CHANGES IN THE EXTENDED PDS...IN PARTICULAR MON THRU WED BASED ON 00Z ECM TRENDING TWD DRIER GFS SOLUTION. FIRST THOUGH...ANTICIPATED MODERATE WARMING TREND THRU EARLY NEXT APPEARS TO BE ON TRACK. ALL THIS IN PART TO LARGE SCALE FLOW TRANSITIONING TO SWLY WITH GRADUAL HGT RISES SPREADING OVER THE CNTRL PLAINS. AND AT THIS POINT...MET/MEX/ECE MOS PROJECTING HIGHS IN THE LOW/MID 40S LOOK PRETTY REASONABLE. AS FOR PCPN CHANCES NEXT WEEK...WITH THE ECM/GFS IN SOMEWHAT BETTER AGREEMENT...FEEL COMPELLED TO GO DRY ON MONDAY AS WELL AS TRIM POPS BACK TO SLGT TUESDAY THRU THURSDAY. BOTH GENERALLY PLACE BRUNT OF QPF FIELD NORTH OF THE CWA...WHICH THE CMC LENDS SOME CREDENCE TO. BUFKIT/CRITICAL THNKS PROGS GENERALLY SUPPORT RA WITH POSSIBLE RA/SN MIX DURING THE OVERNIGHT HOURS. DEE && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
530 AM CST THU NOV 28 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 332 AM CST THU NOV 28 2013 OVERNIGHT UPPER AIR ANALYSIS INDICATES MID TO UPPER LEVEL TROUGHING OVER THE EASTERN CONUS...WITH A RIDGE OVER THE WEST AND A MID LEVEL LOW OVER THE PACIFIC OFF THE CALIFORNIA COAST. A SUBTLE MID LEVEL PERTURBATION IS ALSO NOTED OVER SOUTHERN MINNESOTA...MOVING SOUTHEAST. MID TO UPPER LEVEL JET ENERGY EXTENDS FROM SOUTH CENTRAL CANADA...SOUTHEAST INTO THE CENTRAL CONUS...AND FINALLY EAST AND NORTHEAST ALONG THE EASTERN CONUS INTO SOUTHEASTERN CANADA. MID TO UPPER LEVEL FLOW OVER OUR AREA MAXES OUT AT AROUND 70KTS BETWEEN 300MB AND 200MB PER 00Z SOUNDING DATA FROM KLBF AND KOAX. WATER VAPOR IMAGERY INDICATES INCREASED VALUES OF MID LEVEL MOISTURE EXTENDING ALONG THE BACK SIDE OF THE WEST COAST RIDGE...AS WELL AS FROM THE PACIFIC EASTWARD INTO MEXICO AND THE SOUTHERN PLAINS. MID LEVEL MOISTURE OVER OUR AREA HOWEVER REMAINS FAIRLY LIMITED. AT THE SURFACE...AN AREA OF LOW BAROMETRIC PRESSURE EXISTS OVER NORTHWEST IOWA JUST AHEAD OF THE AFOREMENTIONED MID LEVEL PERTURBATION...WITH AN ASSOCIATED COLD FRONT EXTENDING FROM WESTERN IOWA INTO SOUTHEASTERN NEBRASKA AND NORTHERN KANSAS. THIS FRONT HAS CLEARED MOST ALL OF OUR CWA AND AS A RESULT...THE LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE NORTH/NORTHWEST. GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL SUGGEST NORTHWESTERLY MID TO UPPER LEVEL FLOW WILL PERSIST OVER OUR AREA THROUGH THE NEXT 24 HOURS AS THE EASTERN CONUS TROUGH AND WESTERN CONUS RIDGE BOTH TREK EAST. THE MID LEVEL PERTURBATION...CURRENTLY OVER SOUTHERN MINNESOTA...IS EXPECTED TO CONTINUE MOVING SOUTHEAST THROUGH THE NEXT 24 HOURS...WITH NO OTHER MID LEVEL SHORTWAVES/PERTURBATIONS EXPECTED TO IMPACT THE REGION. AT THE SURFACE...THE AREA OF LOW BAROMETRIC PRESSURE...CURRENTLY OVER NORTHWEST IOWA...SHOULD ALSO CONTINUE MOVING TO THE EAST/SOUTHEAST THROUGH THE NEXT 24 HOURS...WITH THE ASSOCIATED LOW LEVEL BAROCLINIC ZONE PUSHING FARTHER SOUTH/SOUTHEAST ACROSS THE PLAINS. THE LOW LEVEL WIND FIELD ACROSS OUR AREA SHOULD REMAIN FROM THE NORTH/NORTHWEST THROUGH MUCH OF TODAY AS A RESULT. THAT BEING SAID...GUIDANCE SUGGESTS THE PASSAGE OF A SURFACE RIDGE TO EAST SHOULD ALLOW FOR LOW LEVEL RETURN FLOW ACROSS OUR AREA DURING THE OVERNIGHT HOURS TONIGHT. WITH AN OVERALL LACK IN OMEGA EXPECTED OVER OUR AREA...DRY CONDITIONS ARE CURRENTLY FORECAST THROUGH THE NEXT 24 HOURS. SATELLITE IMAGERY INDICATES A BAND OF STRATUS OVER MUCH OF THE NORTHERN PLAINS THIS MORNING AND THIS STRATUS IS ADVANCING TO THE SOUTH...ABOUT 150 MILES NORTH OF THE AFOREMENTIONED SURFACE FRONT. GUIDANCE FROM THE NAM AND RAP BOTH SHOW THIS STRATUS...WITH HIGH RELATIVE HUMIDITY VALUES AT 925MB NOTED ON PLAN VIEW MAPS...INFILTRATING OUR NORTH/NORTHEASTERN CWA JUST PRIOR TO SUNRISE THIS MORNING...BUT DISSIPATING POST-SUNRISE AS DIABATIC HEATING RESULTS IN INCREASED BOUNDARY LAYER HEIGHT AND MIXING. WENT AHEAD AND PLAYED PRETTY CLOSE TO NAM AND RAP GUIDANCE FOR THE CLOUD FORECAST THROUGH THE FIRST PART OF THE SHORT TERM FORECAST PERIOD...WITH THIS STRATUS EXPECTED TO IMPACT OUR NORTH/NORTHEAST BY 10Z OR 11Z THIS MORNING...AND THEN DISSIPATE BY 15Z OR 16Z. WITH LOW LEVEL RETURN FLOW INFILTRATING THE REGION TONIGHT...THERE ARE INDICATIONS OF ISENTROPIC UPGLIDE AND SATURATION...PRIMARILY ALONG THE 275-285K SURFACES...OVER THE HIGH PLAINS OF KANSAS AND NEBRASKA. ALTHOUGH IT APPEARS MUCH OF OUR CWA SHOULD BE SPARED FROM ANY STRATUS DEVELOPMENT THROUGH 12Z FRIDAY...925MB RELATIVE HUMIDITY PLAN VIEW MAPS FROM THE NAM...OPERATIONAL GFS AND EC ALL SUGGEST OUR EXTREME WEST/SOUTHWEST COULD ACTUALLY OBSERVE QUITE A BIT OF CLOUD COVER TOWARDS SUNRISE FRIDAY AS THE EASTERN PERIPHERY OF THE HIGH PLAINS STRATUS CLIPS THE AREA. WENT AHEAD WITH A BROKEN CEILING ACROSS OUR EXTREME WEST/SOUTHWEST BY 12Z FRIDAY AS A RESULT. THE INTRUSION OF A COOLER LOW LEVEL AIRMASS BEHIND THE LOW LEVEL BAROCLINIC ZONE SHOULD RESULT IN A COOLER DAY TODAY WHEN COMPARED TO WEDNESDAY. HIGH TEMPERATURES GENERALLY IN THE MID 30S ACROSS OUR NORTH...AND INTO THE MID 40S ACROSS OUR SOUTH...ARE FORECAST FOR TODAY AS A RESULT. IT MIGHT OTHERWISE BE REASONABLE TO THINK TONIGHT WILL BE COOLER WHEN COMPARED TO EARLY THIS MORNING...BUT WITH LOW LEVEL RETURN FLOW EXPECTED TO INFILTRATE OUR AREA DURING THE OVERNIGHT HOURS...OVERNIGHT LOWS TONIGHT SHOULD ACTUALLY BE PRETTY CLOSE TO WHAT WE ARE EXPECTING EARLY THIS MORNING. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 332 AM CST THU NOV 28 2013 THE FIRST PART OF THE LONG TERM FORECAST IS DRY WITH ABOVE NORMAL TEMPERATURES...AFTERWHICH A MORE UNSETTLED...COLDER AND MORE CHALLENGING FORECAST TAKES HOLD BY MID NEXT WEEK. A TRANSITIONING WEST/NORTHWEST UPPER LEVEL FLOW WILL KEEP THE REGION MAINLY DRY AND MILD THROUGH THROUGH THE REMAINDER OF THE HOLIDAY WEEKEND. REGIONAL TRAVEL CONCERNS WILL BE NIL...AND BOTH DAYTIME HIGHS AND NIGHTTIME LOWS WILL BE AT OR SLIGHTLY ABOVE SEASONAL NORMALS. ONE NOTABLE WEATHER ELEMENT WILL THE WIND...OR LACK THERE OF ON SATURDAY AND SUNDAY. THAT WILL HELP OFFSET ANY COOLING FROM PASSING CLOUDS THROUGHOUT THE WEEKEND. OVERALL...PRETTY NICE FOR THE END OF NOVEMBER. WARM ADVECTION ASSOCIATED WITH WAVE ACROSS THE NORTHERN PLAINS SUNDAY WILL THICKEN CLOUDS...BUT NOT TOO EXCITED ABOUT INCURRING ANY MEASURABLE PRECIPITATION AT THIS POINT. ACTUALLY THE MILD WEATHER WILL CONTINUE INTO THE FIRST PART OF NEXT WEEK...ALTHOUGH THINGS WILL BE CHANGING AS UPPER LEVEL HEIGHTS LOWER AND WE START TO SEE UPPER LEVEL LOW PRESSURE DEEPEN IN THE GREAT BASIN REGION. AS THE LOW STRENGTHENS...AN INCREASING SOUTH TO SOUTHEAST FLOW ACROSS THE CENTRAL/SOUTHERN PLAINS DEVELOPS WHICH WILL KEEP TEMPERATURES ON THE MILD SIDE MONDAY/TUESDAY. THERE IS SOME MODEL LIKENESS IN OVERALL TRENDS...BUT VERY UNEASY IN TRYING TO PIN DOWN ANY SPECIFIC DETAILS FOR NEXT WEEKS FORECAST AT THIS POINT. WE HAVE BEEN ANTICIPATING A COLD AIR PUSH NEXT WEEK...AND THAT STILL LOOKS ON TRACK FOR ABOUT WEDNESDAY...BUT THE COLD AIR PLUNGE COMES IN PIECES WITH THE COLDEST AIR NOT LIKELY TO MAKE IT INTO THE AREA UNTIL LATER NEXT WEEK. MODELS SUGGEST HEAVIEST PRECIPITATION TRENDS WILL LIKELY BE ACROSS THE DAKOTAS AT THIS POINT...WITH ONLY SMALL CHANCES FOR RAIN OR RAIN/SNOW MIX IN THE FORECAST AT THIS POINT AS THE SYSTEM APPROACHES. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 530 AM CST THU NOV 28 2013 MVFR CONDITIONS EXPECTED TO START THE TAF PERIOD...WITH VFR CONDITIONS EXPECTED 15Z AND BEYOND. AN AREA OF STRATUS HAS BEEN MOVING SOUTH FROM SOUTH DAKOTA ALL NIGHT AND IS NOW MOVING INTO THE GRI AREA. THE CEILING WITHIN THIS STRATUS GENERALLY RANGES BETWEEN 1000FT AND 1500FT AGL...THUS THE MVFR FORECAST 12-15Z. GUIDANCE CONTINUES TO SUGGEST THIS STRATUS WILL LIFT AND BREAK APART AFTER SUNRISE AS INCREASING DIABATIC HEATING ALLOWS FOR INCREASING BOUNDARY LAYER DEPTH AND MIXING. VFR CONDITIONS ARE CURRENTLY EXPECTED TO BE RESTORED BY 15Z...BUT THIS WILL NEED TO BE MONITORED THROUGH THE NEXT FEW HOURS FOR POSSIBLE UPDATES TO THE TAF. THE SURFACE WIND WILL REMAIN FROM THE NORTH/NORTHEAST TODAY...SUSTAINED AT AROUND 10KTS. THE PASSAGE OF A SURFACE RIDGE WILL THEN ALLOW FOR A WEAK...NO GREATER THAN 6KTS...SOUTHEASTERLY LOW LEVEL WIND FIELD OVERNIGHT TONIGHT. VISIBILITY RESTRICTION IS NOT EXPECTED AT GRI THROUGH THE NEXT 24 HOURS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...NOAA/NWS/BRYANT LONG TERM...NOAA/NWS/MORITZ AVIATION...NOAA/NWS/BRYANT
AREA FORECAST DISCUSSION
NWS HASTINGS NE
332 AM CST THU NOV 28 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 332 AM CST THU NOV 28 2013 OVERNIGHT UPPER AIR ANALYSIS INDICATES MID TO UPPER LEVEL TROUGHING OVER THE EASTERN CONUS...WITH A RIDGE OVER THE WEST AND A MID LEVEL LOW OVER THE PACIFIC OFF THE CALIFORNIA COAST. A SUBTLE MID LEVEL PERTURBATION IS ALSO NOTED OVER SOUTHERN MINNESOTA...MOVING SOUTHEAST. MID TO UPPER LEVEL JET ENERGY EXTENDS FROM SOUTH CENTRAL CANADA...SOUTHEAST INTO THE CENTRAL CONUS...AND FINALLY EAST AND NORTHEAST ALONG THE EASTERN CONUS INTO SOUTHEASTERN CANADA. MID TO UPPER LEVEL FLOW OVER OUR AREA MAXES OUT AT AROUND 70KTS BETWEEN 300MB AND 200MB PER 00Z SOUNDING DATA FROM KLBF AND KOAX. WATER VAPOR IMAGERY INDICATES INCREASED VALUES OF MID LEVEL MOISTURE EXTENDING ALONG THE BACK SIDE OF THE WEST COAST RIDGE...AS WELL AS FROM THE PACIFIC EASTWARD INTO MEXICO AND THE SOUTHERN PLAINS. MID LEVEL MOISTURE OVER OUR AREA HOWEVER REMAINS FAIRLY LIMITED. AT THE SURFACE...AN AREA OF LOW BAROMETRIC PRESSURE EXISTS OVER NORTHWEST IOWA JUST AHEAD OF THE AFOREMENTIONED MID LEVEL PERTURBATION...WITH AN ASSOCIATED COLD FRONT EXTENDING FROM WESTERN IOWA INTO SOUTHEASTERN NEBRASKA AND NORTHERN KANSAS. THIS FRONT HAS CLEARED MOST ALL OF OUR CWA AND AS A RESULT...THE LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM THE NORTH/NORTHWEST. GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL SUGGEST NORTHWESTERLY MID TO UPPER LEVEL FLOW WILL PERSIST OVER OUR AREA THROUGH THE NEXT 24 HOURS AS THE EASTERN CONUS TROUGH AND WESTERN CONUS RIDGE BOTH TREK EAST. THE MID LEVEL PERTURBATION...CURRENTLY OVER SOUTHERN MINNESOTA...IS EXPECTED TO CONTINUE MOVING SOUTHEAST THROUGH THE NEXT 24 HOURS...WITH NO OTHER MID LEVEL SHORTWAVES/PERTURBATIONS EXPECTED TO IMPACT THE REGION. AT THE SURFACE...THE AREA OF LOW BAROMETRIC PRESSURE...CURRENTLY OVER NORTHWEST IOWA...SHOULD ALSO CONTINUE MOVING TO THE EAST/SOUTHEAST THROUGH THE NEXT 24 HOURS...WITH THE ASSOCIATED LOW LEVEL BAROCLINIC ZONE PUSHING FARTHER SOUTH/SOUTHEAST ACROSS THE PLAINS. THE LOW LEVEL WIND FIELD ACROSS OUR AREA SHOULD REMAIN FROM THE NORTH/NORTHWEST THROUGH MUCH OF TODAY AS A RESULT. THAT BEING SAID...GUIDANCE SUGGESTS THE PASSAGE OF A SURFACE RIDGE TO EAST SHOULD ALLOW FOR LOW LEVEL RETURN FLOW ACROSS OUR AREA DURING THE OVERNIGHT HOURS TONIGHT. WITH AN OVERALL LACK IN OMEGA EXPECTED OVER OUR AREA...DRY CONDITIONS ARE CURRENTLY FORECAST THROUGH THE NEXT 24 HOURS. SATELLITE IMAGERY INDICATES A BAND OF STRATUS OVER MUCH OF THE NORTHERN PLAINS THIS MORNING AND THIS STRATUS IS ADVANCING TO THE SOUTH...ABOUT 150 MILES NORTH OF THE AFOREMENTIONED SURFACE FRONT. GUIDANCE FROM THE NAM AND RAP BOTH SHOW THIS STRATUS...WITH HIGH RELATIVE HUMIDITY VALUES AT 925MB NOTED ON PLAN VIEW MAPS...INFILTRATING OUR NORTH/NORTHEASTERN CWA JUST PRIOR TO SUNRISE THIS MORNING...BUT DISSIPATING POST-SUNRISE AS DIABATIC HEATING RESULTS IN INCREASED BOUNDARY LAYER HEIGHT AND MIXING. WENT AHEAD AND PLAYED PRETTY CLOSE TO NAM AND RAP GUIDANCE FOR THE CLOUD FORECAST THROUGH THE FIRST PART OF THE SHORT TERM FORECAST PERIOD...WITH THIS STRATUS EXPECTED TO IMPACT OUR NORTH/NORTHEAST BY 10Z OR 11Z THIS MORNING...AND THEN DISSIPATE BY 15Z OR 16Z. WITH LOW LEVEL RETURN FLOW INFILTRATING THE REGION TONIGHT...THERE ARE INDICATIONS OF ISENTROPIC UPGLIDE AND SATURATION...PRIMARILY ALONG THE 275-285K SURFACES...OVER THE HIGH PLAINS OF KANSAS AND NEBRASKA. ALTHOUGH IT APPEARS MUCH OF OUR CWA SHOULD BE SPARED FROM ANY STRATUS DEVELOPMENT THROUGH 12Z FRIDAY...925MB RELATIVE HUMIDITY PLAN VIEW MAPS FROM THE NAM...OPERATIONAL GFS AND EC ALL SUGGEST OUR EXTREME WEST/SOUTHWEST COULD ACTUALLY OBSERVE QUITE A BIT OF CLOUD COVER TOWARDS SUNRISE FRIDAY AS THE EASTERN PERIPHERY OF THE HIGH PLAINS STRATUS CLIPS THE AREA. WENT AHEAD WITH A BROKEN CEILING ACROSS OUR EXTREME WEST/SOUTHWEST BY 12Z FRIDAY AS A RESULT. THE INTRUSION OF A COOLER LOW LEVEL AIRMASS BEHIND THE LOW LEVEL BAROCLINIC ZONE SHOULD RESULT IN A COOLER DAY TODAY WHEN COMPARED TO WEDNESDAY. HIGH TEMPERATURES GENERALLY IN THE MID 30S ACROSS OUR NORTH...AND INTO THE MID 40S ACROSS OUR SOUTH...ARE FORECAST FOR TODAY AS A RESULT. IT MIGHT OTHERWISE BE REASONABLE TO THINK TONIGHT WILL BE COOLER WHEN COMPARED TO EARLY THIS MORNING...BUT WITH LOW LEVEL RETURN FLOW EXPECTED TO INFILTRATE OUR AREA DURING THE OVERNIGHT HOURS...OVERNIGHT LOWS TONIGHT SHOULD ACTUALLY BE PRETTY CLOSE TO WHAT WE ARE EXPECTING EARLY THIS MORNING. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 332 AM CST THU NOV 28 2013 THE FIRST PART OF THE LONG TERM FORECAST IS DRY WITH ABOVE NORMAL TEMPERATURES...AFTERWHICH A MORE UNSETTLED...COLDER AND MORE CHALLENGING FORECAST TAKES HOLD BY MID NEXT WEEK. A TRANSITIONING WEST/NORTHWEST UPPER LEVEL FLOW WILL KEEP THE REGION MAINLY DRY AND MILD THROUGH THROUGH THE REMAINDER OF THE HOLIDAY WEEKEND. REGIONAL TRAVEL CONCERNS WILL BE NIL...AND BOTH DAYTIME HIGHS AND NIGHTTIME LOWS WILL BE AT OR SLIGHTLY ABOVE SEASONAL NORMALS. ONE NOTABLE WEATHER ELEMENT WILL THE WIND...OR LACK THERE OF ON SATURDAY AND SUNDAY. THAT WILL HELP OFFSET ANY COOLING FROM PASSING CLOUDS THROUGHOUT THE WEEKEND. OVERALL...PRETTY NICE FOR THE END OF NOVEMBER. WARM ADVECTION ASSOCIATED WITH WAVE ACROSS THE NORTHERN PLAINS SUNDAY WILL THICKEN CLOUDS...BUT NOT TOO EXCITED ABOUT INCURRING ANY MEASURABLE PRECIPITATION AT THIS POINT. ACTUALLY THE MILD WEATHER WILL CONTINUE INTO THE FIRST PART OF NEXT WEEK...ALTHOUGH THINGS WILL BE CHANGING AS UPPER LEVEL HEIGHTS LOWER AND WE START TO SEE UPPER LEVEL LOW PRESSURE DEEPEN IN THE GREAT BASIN REGION. AS THE LOW STRENGTHENS...AN INCREASING SOUTH TO SOUTHEAST FLOW ACROSS THE CENTRAL/SOUTHERN PLAINS DEVELOPS WHICH WILL KEEP TEMPERATURES ON THE MILD SIDE MONDAY/TUESDAY. THERE IS SOME MODEL LIKENESS IN OVERALL TRENDS...BUT VERY UNEASY IN TRYING TO PIN DOWN ANY SPECIFIC DETAILS FOR NEXT WEEKS FORECAST AT THIS POINT. WE HAVE BEEN ANTICIPATING A COLD AIR PUSH NEXT WEEK...AND THAT STILL LOOKS ON TRACK FOR ABOUT WEDNESDAY...BUT THE COLD AIR PLUNGE COMES IN PIECES WITH THE COLDEST AIR NOT LIKELY TO MAKE IT INTO THE AREA UNTIL LATER NEXT WEEK. MODELS SUGGEST HEAVIEST PRECIPITATION TRENDS WILL LIKELY BE ACROSS THE DAKOTAS AT THIS POINT...WITH ONLY SMALL CHANCES FOR RAIN OR RAIN/SNOW MIX IN THE FORECAST AT THIS POINT AS THE SYSTEM APPROACHES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1133 PM CST WED NOV 27 2013 VFR CONDITIONS EXPECTED THROUGH 11Z...WITH MVFR CONDITIONS FORECAST 11-18Z...FOLLOWED BY VFR CONDITIONS 18Z ONWARD. LITTLE IN THE WAY OF CLOUD COVER WILL BE OBSERVED TO START THE TAF PERIOD. STRATUS...CURRENTLY OVER SOUTH DAKOTA...IS SURGING TOWARD THE AREA AND MAY IMPACT THE AREA TOWARDS SUNRISE THURSDAY. BASED ON CURRENT OBSERVATIONS ACROSS SOUTH DAKOTA...AS WELL AS CURRENT GUIDANCE...WENT AHEAD WITH A CEILING AROUND 1500FT AGL STARTING AT 11Z. THE SURFACE WIND WILL REMAIN FROM THE NORTH/NORTHWEST AT AROUND 10KTS THROUGH THE OVERNIGHT HOURS AND INTO THURSDAY MORNING...THEN BECOMING LIGHT AND VARIABLE HEADING INTO THE AFTERNOON HOURS THURSDAY. VISIBILITY RESTRICTION IS NOT EXPECTED AT GRI THROUGH THE NEXT 24 HOURS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...NOAA/NWS/BRYANT LONG TERM...NOAA/NWS/MORITZ AVIATION...NOAA/NWS/BRYANT
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
131 AM EST THU NOV 28 2013 .SYNOPSIS... A STORM SYSTEM OVER NEW ENGLAND WILL CONTINUE MOVING NORTHEAST TONIGHT. STEADY SNOW WILL END THIS EVENING, BUT LAKE EFFECT SNOW SHOWERS WILL SET UP ACROSS UPSTATE NEW YORK TONIGHT AND CONTINUE INTO THANKSGIVING NIGHT. HIGH PRESSURE AND DRY WEATHER WILL RETURN FRIDAY NIGHT TO SATURDAY NIGHT. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 920 PM UPDATE... REDUCED OVERNIGHT SNOWFALL AMOUNTS IN PROJECTED BANDS FROM AROUND 2 TO 3 INCHES, DOWN TO 1.5 TO 2 INCHES. THIS IS MOSTLY FROM A REDUCTION IN THE FIRST 6 HOURS, AS BAND INTO SYR AREA HAS NOT YET SHOWN SIGNS OF FORMING. LATEST HRRR HAS A PRETTY GOOD HANDLE ON THE RADAR DEPICTION, AND IT KEEPS THE RETURNS PRETTY LIGHT THROUGH THE NEXT FEW HOURS. STILL ANTICIPATE BAND INTENSIFICATION SOMETIME BETWEEN 7Z AND 9Z, WITH MOST OF THE OVERNIGHT SNOW ACCUMULATION COMING IN THE FINAL 6 HOURS OF THE OVERNIGHT PERIOD. 515 PM UPDATE... QUICK UPDATE TO LOWER POPS TO SLIGHT CHANCE OVER NY COUNTIES WEST OF I-81 IN LOWER DEWPOINT ATMOSPHERE. BACK EDGE OF SYNOPTIC SNOW IS ALONG THE I-81 CORRIDOR EASTWARD. WESTWARD - JUST A FEW RADAR RETURNS AND MAJORITY OF OBS ARE REPORTING DRY WEATHER. AS THE EVENING WEARS ON...THE EVENT WILL TRANSITION TO LAKE EFFECT OVER NORTHERN FA. 3 PM UPDATE... BACK EDGE OF SYNOPTIC PRECIP STILL IN NE PA AND THE CATSKILLS. RAIN HAS NOW MOSTLY CHANGED TO SNOW. THIS WILL LIFT NE BY 6 PM AS THE LARGE SFC LOW IN EASTERN NEW ENGLAND. NW FLOW ACROSS THE ENTIRE CWA WITH WEAK LAKE EFFECT STARTING. AS THE LOW LEVEL FLOW ALIGNS AND COLDER AIR COMES IN THE LAKE EFFECT SNOW WILL EXPAND IN COVERAGE AND INCREASE IN INTENSITY. WITH A 320 FLOW IT WILL BE MULTIBANDS. GEORGIAN BAY CONNECTION COMES INTO PLAY AS THE FLOW SHIFTS SOME TO WNW. MOISTURE DEPTH OF 10KT. DENDRITE ZONE OF 2K FT STARTS AROUND 6K THEN DROPS TO 4K LATE TONIGHT. GOOD LIFT THROUGH THE MOISTURE AND DENDRITE ZONES. ISSUED A LES ADVISORY FOR ONONDAGA ONEIDA MADISON FOR TONIGHT TO THU NGT. OUTSIDE OF THE LAKE EFFECT IN CENTRAL NY...NE PA WILL BE CLOUDY AND MOSTLY DRY. CAA IS STRONG WITH TEMPS FALLING UPPER TEENS AND L20S. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY/... 3 PM UPDATE... THU MORNING A LULL BEFORE A SHORT WAVE DROPS SE HELPING TO ENHANCE THE LAKE EFFECT. LOW LEVEL FLOW SHIFTS TO 290 BRINGING THE BEST BAND INTO SYRACUSE AND ONEIDA AND CAZENOVIA. THIS BAND WILL CONTINUE INTO THE EVENING BEFORE WEAKENING LATE THU NGT. MULTILAKE CONNECTION FROM GEORGIAN BAY. COULD BE A GOOD ENOUGH BAND FOR HALF AN INCH TO AN INCH AN HOUR SNOW. HEAVIEST SNOW TOTALS THU PM 3 TO 5 INCHES. FRIDAY COLD NW LOW LEVEL FLOW STILL GOING AS A LARGE DRY CANADIAN HIGH PRESSURE MOVES IN FROM THE NW. LL FLOW BECOMES LIGHT AND IS SHEARED SO SNOW ACCUMULATIONS WILL BE LESS THAN 2 INCHES EVERYWHERE BEFORE LES SHUTS DOWN FRI AFTN. HIGH OVER THE CWA FRI NGT AND STALLS INTO SAT NGT. WAA AT 850MB KICKS IN WHILE UPPER LEVEL HEIGHTS RISE. SFC TEMPS STILL BELOW NORMAL AND MOSTLY BELOW FREEZING. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... PD BEGINS WITH A WEAK WV DROPPING THRU THE GREAT LAKES. DFRNCS BETWEEN THE EURO AND GFS WILL HAVE LTL EFFECT ON THE SENSIBLE WX FOR THE SYSTEM WHICH LOOKS TO GENERATE SOME LGT PCPNSAT NGT INTO SUNDAY. TEMPS MRGNL...BUT LOOKS COLD ENUF FOR SOME LGT SNOW MOST PLACE...ESP NORTH. SLGTLY MILDER OVER NEPA BUT WITH A LWR CHANCE PF PCPN IT MAY NOT MAKE MUCH DFRNC. SYSTEM, PASSES THRU SUN BUT LEAVES THE AREA IN A SHALLOW UT BROAD UPR TROF OVER THE LAKES...AND WEAK AREA OF MOISTURE PCPN. EURO SUGGESTS SOME WEAK CSTL DVLPMT ON TUE PERHAPS ORGANIZING THE PCPN A BIT MORE. GFS HAS DVLPMT FURTHER OUT TO SEA BUT STILL SOME ENHANCED PCPN OVER THE ERN ZONES. HWVR...IN GNRL JUST A SEASONABLY COOL PD WITH LGT PCPN AT TIMES. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... A BRISK NORTHWEST FLOW WILL PREVAIL ACROSS THE AREA THROUGH THIS TAF PERIOD WITH WIDESPREAD MVFR CIGS AND FLURRIES EXPECTED AT ALL TERMINALS EXCEPT FOR KELM/KAVP WHERE CONDITIONS WILL BE PRIMARILY VFR. AT KSYR, A LAKE EFFECT SNOWBAND CONTINUES TO PRODUCE IFR RESTRICTIONS NOW. IT APPEARS BASED ON RADAR AND MODEL SOUNDINGS SHOWING DRIER AIR WORKING IN FROM ABOVE...THAT THE BEST SHOT FOR IFR WILL COME OVER THE NEXT FEW HOURS. WITH THE 09Z UPDATE I MAY HAVE TO REMOVE IFR VSBYS THAT WE CURRENTLY HAVE NEAR DAYBREAK. LATER TODAY AS MOISTURE INCREASES IN THE COLUMN...MORE LAKE SNOWS ARE POSSIBLE ESPECIALLY AT KRME AND KSYR WITH IFR VSBYS POSSIBLE. NORTHWEST WINDS 10-15 KNOTS WITH GUSTS AROUND 25 KNOTS DIMINISHING TO 10-12 KNOTS BY MID MORNING THURSDAY. OUTLOOK... THU NIGHT TO SUN MORN...MAINLY VFR. SUN AFTN TO MON...MVFR AND MAYBE IFR IN MIXED PRECIP. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST FRIDAY FOR NYZ009-018- 036-037. && $$ SYNOPSIS...TAC NEAR TERM...DJP/TAC SHORT TERM...TAC LONG TERM...DGM AVIATION...HEDEN/RRM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
306 PM CST THU NOV 28 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 306 PM CST THU NOV 28 2013 THE MAIN FORECAST ISSUE IN THE SHORT TERM PERIOD WILL BE SKY COVER TONIGHT AND IMPACT ON TEMPERATURES. PORTIONS OF THE STRATUS DECK HAVE ERODED ACROSS THE FORECAST AREA THIS AFTERNOON. RAP 925MB RELATIVE HUMIDITY HAS THIS MODELED RELATIVELY WELL AND SUGGEST THAT STRATUS SHOULD FILL BACK IN THIS EVENING AND OVERNIGHT. TEMPERATURES WILL LIKELY DROP QUICKLY THIS EVENING IN CLOUD FREE AREAS...BEFORE THE STRONGER SE WINDS DEVELOP. THE STRONGER GRADIENT WILL BE LOCATED OVER THE WEST AND HAVE KEPT OVERNIGHT LOWS RELATIVELY MILD...IN THE TEENS TO LOWER 20S. EAST/NORTHEAST PORTIONS OF THE FORECAST AREA...FROM THE TURTLE MOUNTAINS THROUGH THE JAMES RIVER VALLEY...SHOULD BE ABLE TO GET INTO THE SINGLE DIGITS. HOURLY TRENDS WILL LIKELY NEED TO BE UPDATED THIS EVENING. ON FRIDAY...STRONGER WARM AIR ADVECTION WILL KICK IN...WITH HIGHS IN THE MID 20S NORTHEAST TO LOWER 40S SOUTHWEST. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 306 PM CST THU NOV 28 2013 THE HIGHLIGHT OF THE EXTENDED FORECAST IS THE RETURN OF ARCTIC AIR AND THE POTENTIAL FOR WIDESPREAD ACCUMULATING SNOW NEXT WEEK. THE 12 UTC GUIDANCE SUITE IS IN GOOD AGREEMENT ON A SIGNIFICANT UPPER LEVEL LOW COMING ONSHORE TO THE PACIFIC NORTHWEST ON MONDAY. THEREAFTER...UNCERTAINTY INCREASES IN REGARDS TO THE EVOLUTION AND PROPAGATION OF THIS LOW ACROSS THE INTERMOUNTAIN WEST AND POTENTIALLY INTO THE NORTHERN PLAINS LATE TUESDAY AND INTO WEDNESDAY. THE 12 UTC ECMWF CONTINUES THE TREND OF ITS PREVIOUS RUNS OVER THE PAST 24 HOURS OF THE DEEPEST LOW YIELDING SIGNIFICANT QPF AND SNOW ACROSS THE NORTHERN PLAINS TUESDAY INTO WEDNESDAY. THE 12 UTC GFS HAS TRENDED MORE TOWARDS THE ECMWF...HOWEVER...IS NOT AS DEEP WITH LESSER QPF...MUCH LIKE THE 12 UTC GEM. THE ECMWF HAS BEEN THE MOST CONSISTENT AND IS SUPPORTED BY THE GEFS MEAN...AND FAVORED BY WPC. THUS...WILL CONTINUE TO MONITOR THE POTENTIAL FOR ACCUMULATING SNOW NEXT WEEK. NO MATTER THE MODEL...ARCTIC AIR IS FORECAST TO OVERTAKE THE NORTHERN PLAINS ONCE AGAIN TUESDAY THROUGH THE END OF NEXT WEEK WITH A PATTERN SHIFT TO BROAD WESTERN AND CENTRAL CONUS UPPER LEVEL TROUGHING. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 306 PM CST THU NOV 28 2013 EXPECT MAINLY MVFR CEILINGS THROUGH TONIGHT...WITH SOME PERIODS THIS AFTERNOON WHEN CLOUDS SCATTER OUT...ESPECIALLY AT KDIK/KJMS/KMOT. A FEW FLURRIES WILL PERSIST. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM/AVIATION...RP KINNEY LONG TERM...AYD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1234 PM CST THU NOV 28 2013 .UPDATE... ISSUED AT 1228 PM CST THU NOV 28 2013 TEMPERATURES HAVE BEEN SLOW TO RECOVER OVER PORTIONS OF NW MN LIKELY A RESULT OF FRESH SNOW COVER AND LOWERED MAXIMUM TEMPERATURES 3-5 DEGREES. TEMPERATURES ON TRACK ELSEWHERE WHERE PARTIAL SOLAR HELPING THE SLIGHT RECOVERY EXPECTED. NO OTHER CHANGES MADE TO ONGOING FORECAST. UPDATE ISSUED AT 936 AM CST THU NOV 28 2013 MAIN CHALLENGE TODAY WILL BE CLOUD TRENDS AND TEMPERATURES. LATEST SATELLITE IMAGERY SHOWING A GENERAL DECREASE IN CLOUD COVER ACROSS THE REGION BEST DEPICTED BY RAP MESO-MODEL. WILL CONTINUE WITH A GRADUAL DECREASE IN CLOUDS THROUGH THE MORNING BASED ON RAP GUIDANCE AND CURRENT TRENDS. AT THIS POINT WITH EXPECTED PARTIAL SOLAR WILL HOLD WITH TEMPERATURES FOR NOW. ONLY CHANGES WERE MINOR CLOUD TREND ADJUSTMENTS. UPDATE ISSUED AT 641 AM CST THU NOV 28 2013 CLOUDS CONTINUE TO BE A CHALLENGE. RAP/HRRR CIG GUIDANCE INITIALIZES WITH CLEAR SKIES...BUT THEN DEVELOPS LOW CIGS DURING THE AFTERNOON HOURS (LIKELY CU...LOW CONVECTIVE TEMPS) WHICH GET TRAPPED UNDER THE RIDGE TONIGHT. RAP 925MB-850MB RH FIELD ACTUALLY INDICATES THE DRYING THAT IS WORKING THROUGH THE VALLEY...AND PROBABLY IS CLOSEST TO THE TRUTH. ADJUSTED THE SKY GRIDS FOR CURRENT OBSERVATIONS AND LATEST RAP 925MB-850MB RH. NO MAJOR CHANGES YET UNTIL MORE CONFIDENCE CAN BE OBTAINED WITH WHAT EVER THE CLOUDS WILL DO TODAY. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 300 AM CST THU NOV 28 2013 NORTHWEST FLOW ALOFT WILL CONTINUE INTO FRIDAY...WITH ANOTHER SHORTWAVE EXPECTED FRIDAY INTO FRIDAY NIGHT. 00Z MODELS INDICATE THAT THIS NEXT SHORTWAVE WILL TRACK FURTHER NORTH THAN THE ONE YESTERDAY...KEEPING ACCUMULATING SNOWFALL OUTSIDE OF THE FA. FOR TODAY...THE REGION WILL BE BETWEEN SHORTWAVES AS HIGH PRESSURE BUILDS FROM THE NORTH. THIS WILL LEAVE CLOUD TRENDS AS THE MAIN CHALLENGE. 09Z SATELLITE IMAGERY SHOWS CLEARING WORKING INTO THE NORTHERN VALLEY. MODELS ARE STRUGGLING WITH THE CURRENT CLOUD COVER...ALTHOUGH THE 07Z RAP IS CLOSEST WHEN LOOKING AT THE 925MB- 850MB RH FIELD. THIS MODEL INDICATES THAT CLEARING WILL CONTINUE TO MOVE DOWN THE VALLEY...WITH CLOUDS DISSIPATING ALONG BOTH EDGES THROUGH THE DAY. THIS SCENARIO MAKES SOME SENSE WITH THE HIGH BUILDING INTO THE REGION. HOWEVER...CONVECTIVE TEMPS WILL BE IN THE TEENS UNTIL LATE AFTERNOON...WHICH COULD LEAD TO REDEVELOPMENT WITHIN CLEARING AREAS. DID DELAY THE CLEARING...BUT REMAINED OPTIMISTIC THAT MOST AREAS WILL CLEAR THIS AFTERNOON. ALSO...CONSIDERING CURRENT CONDITIONS...MENTIONED FLURRIES WITHIN EXPECTED CLOUDY AREAS. MIN TEMPS TONIGHT VERY DEPENDENT ON WHETHER OR NOT WE GET RID OF THE CLOUDS TODAY. IF WE DO CLEAR...THERE WILL LIKELY WILL BE A QUICK DROP THIS EVENING BEFORE RETURN FLOW KICKS IN AND TEMPS BECOME STEADY AFTER MIDNIGHT. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 300 AM CST THU NOV 28 2013 FRIDAY NIGHT-SATURDAY NIGHT...HIGH PRESSURE MOVING THROUGH SHOULD LEAD TO DRY WEATHER. NOT SURE ABOUT CLOUD COVER (CONSIDERING CURRENT CONDITIONS FOLLOWING A SHORTWAVE). CURRENT THOUGHT IS THAT SINCE THE FRIDAY SHORTWAVE WILL TRACK FURTHER NORTH THAN THE CURRENT SYSTEM...SHOULD BE LESS CLOUDS. ALSO...ANTICIPATE A WARMER AIRMASS. SUNDAY-WEDNESDAY...DETERMINISTIC MODEL RUNS CONTINUE TO SUGGEST A MORE ACTIVE PATTERN TAKING SHAPE NEXT WEEK AS AN UPPER WAVE CURRENTLY ACROSS ALASKA DIVES SOUTHWARD INTO THE WESTERN CONUS DURING THE FIRST HALF OF NEXT WEEK...WITH ZONAL FLOW TRANSITIONING TO SOUTHWEST FLOW ALOFT DOWNSTREAM ACROSS THE PLAINS. 00Z MODELS SUGGEST THE POTENTIAL FOR SOME LIGHT SNOW WITH WARM ADVECTION LATER SUNDAY INTO MONDAY. BEYOND THIS POINT...CONFIDENCE REGARDING ANY PARTICULAR DETAILS IS VERY LOW...WITH SIGNIFICANT DIFFERENCES AMONG MODELS IN HANDLING THE UPPER LONGWAVE TROUGH AND TIMING/PLACEMENT OF EMBEDDED SHORTWAVE TROUGHS. THE LOW TO MID-LEVEL BAROCLINIC ZONE WILL REMAIN POSITIONED ACROSS THE NORTHERN PLAINS THROUGH MID-WEEK BEFORE ADVANCING SOUTHWARD. ANY WAVE EJECTING OUT OF THE BROADER TROUGH TO THE WEST ALONG THIS BAROCLINIC ZONE WILL NEED TO BE WATCHED FOR SFC CYCLONE DEVELOPMENT...WITH THE 00Z ECMWF INDICATING A MORE SIGNIFICANT WAVE FOR THE MIDDLE OF THE WEEK. GIVEN THE VARIED MODEL SOLUTIONS...CONTINUED WITH BROAD BRUSHED SLIGHT/CHANCE POPS THROUGH MUCH OF THE PERIOD. TEMPS THROUGH MID-WEEK LOOK TO BE SEASONABLE BEFORE COLDER AIR ARRIVES LATE IN THE WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1228 PM CST THU NOV 28 2013 MVFR CEILINGS WITH PATCHY LIGHT SNOW/FLURRIES CONTINUE ACROSS THE FAR EASTERN PORTIONS OF THE FA...THIS INCLUDES KTVF AND KBJI. OTHERWISE...SKIES HAVE UNDERGONE A CLEARING TREND IN THE HEART OF THE RED RIVER VALLEY AND SOUTHERN PORTIONS OF THE FA. THESE TRENDS SHOULD CONTINUE FOR THE REMAINDER OF THE DAYLIGHT HOURS. CLOUD COVER IS THEN EXPECTED TO INCREASE AGAIN ACROSS THE NORTHERN FA AFTER 00Z AND CONTINUING OVERNIGHT. SURFACE WINDS WILL SLACKEN IN THE EVENING AND THEN BEGIN TO TURN AROUND OUT OF THE SOUTHEAST AS THE SURFACE RIDGE PASSES TO THE EAST OF THE REGION. THE WINDS SHOULD INCREASE AFTER SUNRISE ON FRIDAY AND GUST TO AROUND 20 KNOTS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...VOELKER SHORT TERM...TG LONG TERM...TG/MAKOWSKI AVIATION...BRAMER
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
940 AM CST THU NOV 28 2013 .UPDATE... ISSUED AT 936 AM CST THU NOV 28 2013 MAIN CHALLENGE TODAY WILL BE CLOUD TRENDS AND TEMPERATURES. LATEST SATELLITE IMAGERY SHOWING A GENERAL DECREASE IN CLOUD COVER ACROSS THE REGION BEST DEPICTED BY RAP MESO-MODEL. WILL CONTINUE WITH A GRADUAL DECREASE IN CLOUDS THROUGH THE MORNING BASED ON RAP GUIDANCE AND CURRENT TRENDS. AT THIS POINT WITH EXPECTED PARTIAL SOLAR WILL HOLD WITH TEMPERATURES FOR NOW. ONLY CHANGES WERE MINOR CLOUD TREND ADJUSTMENTS. UPDATE ISSUED AT 641 AM CST THU NOV 28 2013 CLOUDS CONTINUE TO BE A CHALLENGE. RAP/HRRR CIG GUIDANCE INITIALIZES WITH CLEAR SKIES...BUT THEN DEVELOPS LOW CIGS DURING THE AFTERNOON HOURS (LIKELY CU...LOW CONVECTIVE TEMPS) WHICH GET TRAPPED UNDER THE RIDGE TONIGHT. RAP 925MB-850MB RH FIELD ACTUALLY INDICATES THE DRYING THAT IS WORKING THROUGH THE VALLEY...AND PROBABLY IS CLOSEST TO THE TRUTH. ADJUSTED THE SKY GRIDS FOR CURRENT OBSERVATIONS AND LATEST RAP 925MB-850MB RH. NO MAJOR CHANGES YET UNTIL MORE CONFIDENCE CAN BE OBTAINED WITH WHAT EVER THE CLOUDS WILL DO TODAY. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 300 AM CST THU NOV 28 2013 NORTHWEST FLOW ALOFT WILL CONTINUE INTO FRIDAY...WITH ANOTHER SHORTWAVE EXPECTED FRIDAY INTO FRIDAY NIGHT. 00Z MODELS INDICATE THAT THIS NEXT SHORTWAVE WILL TRACK FURTHER NORTH THAN THE ONE YESTERDAY...KEEPING ACCUMULATING SNOWFALL OUTSIDE OF THE FA. FOR TODAY...THE REGION WILL BE BETWEEN SHORTWAVES AS HIGH PRESSURE BUILDS FROM THE NORTH. THIS WILL LEAVE CLOUD TRENDS AS THE MAIN CHALLENGE. 09Z SATELLITE IMAGERY SHOWS CLEARING WORKING INTO THE NORTHERN VALLEY. MODELS ARE STRUGGLING WITH THE CURRENT CLOUD COVER...ALTHOUGH THE 07Z RAP IS CLOSEST WHEN LOOKING AT THE 925MB- 850MB RH FIELD. THIS MODEL INDICATES THAT CLEARING WILL CONTINUE TO MOVE DOWN THE VALLEY...WITH CLOUDS DISSIPATING ALONG BOTH EDGES THROUGH THE DAY. THIS SCENARIO MAKES SOME SENSE WITH THE HIGH BUILDING INTO THE REGION. HOWEVER...CONVECTIVE TEMPS WILL BE IN THE TEENS UNTIL LATE AFTERNOON...WHICH COULD LEAD TO REDEVELOPMENT WITHIN CLEARING AREAS. DID DELAY THE CLEARING...BUT REMAINED OPTIMISTIC THAT MOST AREAS WILL CLEAR THIS AFTERNOON. ALSO...CONSIDERING CURRENT CONDITIONS...MENTIONED FLURRIES WITHIN EXPECTED CLOUDY AREAS. MIN TEMPS TONIGHT VERY DEPENDENT ON WHETHER OR NOT WE GET RID OF THE CLOUDS TODAY. IF WE DO CLEAR...THERE WILL LIKELY WILL BE A QUICK DROP THIS EVENING BEFORE RETURN FLOW KICKS IN AND TEMPS BECOME STEADY AFTER MIDNIGHT. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 300 AM CST THU NOV 28 2013 FRIDAY NIGHT-SATURDAY NIGHT...HIGH PRESSURE MOVING THROUGH SHOULD LEAD TO DRY WEATHER. NOT SURE ABOUT CLOUD COVER (CONSIDERING CURRENT CONDITIONS FOLLOWING A SHORTWAVE). CURRENT THOUGHT IS THAT SINCE THE FRIDAY SHORTWAVE WILL TRACK FURTHER NORTH THAN THE CURRENT SYSTEM...SHOULD BE LESS CLOUDS. ALSO...ANTICIPATE A WARMER AIRMASS. SUNDAY-WEDNESDAY...DETERMINISTIC MODEL RUNS CONTINUE TO SUGGEST A MORE ACTIVE PATTERN TAKING SHAPE NEXT WEEK AS AN UPPER WAVE CURRENTLY ACROSS ALASKA DIVES SOUTHWARD INTO THE WESTERN CONUS DURING THE FIRST HALF OF NEXT WEEK...WITH ZONAL FLOW TRANSITIONING TO SOUTHWEST FLOW ALOFT DOWNSTREAM ACROSS THE PLAINS. 00Z MODELS SUGGEST THE POTENTIAL FOR SOME LIGHT SNOW WITH WARM ADVECTION LATER SUNDAY INTO MONDAY. BEYOND THIS POINT...CONFIDENCE REGARDING ANY PARTICULAR DETAILS IS VERY LOW...WITH SIGNIFICANT DIFFERENCES AMONG MODELS IN HANDLING THE UPPER LONGWAVE TROUGH AND TIMING/PLACEMENT OF EMBEDDED SHORTWAVE TROUGHS. THE LOW TO MID-LEVEL BAROCLINIC ZONE WILL REMAIN POSITIONED ACROSS THE NORTHERN PLAINS THROUGH MID-WEEK BEFORE ADVANCING SOUTHWARD. ANY WAVE EJECTING OUT OF THE BROADER TROUGH TO THE WEST ALONG THIS BAROCLINIC ZONE WILL NEED TO BE WATCHED FOR SFC CYCLONE DEVELOPMENT...WITH THE 00Z ECMWF INDICATING A MORE SIGNIFICANT WAVE FOR THE MIDDLE OF THE WEEK. GIVEN THE VARIED MODEL SOLUTIONS...CONTINUED WITH BROAD BRUSHED SLIGHT/CHANCE POPS THROUGH MUCH OF THE PERIOD. TEMPS THROUGH MID-WEEK LOOK TO BE SEASONABLE BEFORE COLDER AIR ARRIVES LATE IN THE WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 641 AM CST THU NOV 28 2013 LOW CONFIDENCE FORECAST FOR TODAY AS GUIDANCE IS PERFORMING POORLY WITH THE CURRENT SITUATION. THE MOST LIKELY SCENARIO IS THAT MVFR CIGS WILL REMAIN WEST OF THE VALLEY THROUGH MUCH OF THE DAY...BREAKING UP BY THIS EVENING. SKY WITHIN THE VALLEY (KGFK/KFAR) IS CURRENTLY CLEAR...AND SHOULD REMAIN THAT WAY (WITH A BRIEF PERIOD OF MVFR CU DEVELOPMENT MID-DAY). ANTICIPATE CLEARING EAST OF THE VALLEY BY EARLY TO MID AFTERNOON. WILL AMEND THE TAFS IF MORE CONFIDENCE CAN BE OBTAINED. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...VOELKER SHORT TERM...TG LONG TERM...TG/MAKOWSKI AVIATION...TG
AREA FORECAST DISCUSSION
NWS BISMARCK ND
646 AM CST THU NOV 28 2013 .UPDATE... ISSUED AT 646 AM CST THU NOV 28 2013 HIGH RESOLUTION MODELS INCLUDING RAP AND NAM NOT SHOWING MUCH INDICATION OF LOW STRATUS SCATTERING OUT ANYTIME SOON. LATEST SATELLITE IMAGERY DOES SHOW CLEARING WORKING SOUTH INTO SOUTHWESTERN MANITOBA...AND THE LATEST RAP DOES DEPICT THIS AND CONTINUES THE CLEARING SOUTH. THUS TRENDING SKY CONDITIONS SCT-BKN OVER MY EAST AS THIS CLEARING DEVELOPS SOUTHWARD. MODELS ALSO INDICATING THE WESTERN EDGE OF THE STRATUS DECK ERODING SO TRENDED SKY OVER SOUTHWEST ND SCT-BKN AS WELL. OTHERWISE DO NOT SEE CIGS SCOURING OUT TODAY ELSEWHERE. PIREP REPORTS FROM LAST EVENING INDICATED THE THICKNESS OF THE STRATUS DECK AT AROUND 1500FT...SO MAY ONLY SEE THE EDGES ERODING TODAY WITH REDEVELOPMENT TONIGHT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 419 AM CST THU NOV 28 2013 CURRENTLY...ARCTIC HIGH PRESSURE WAS CENTERED OVER NORTHERN MANITOBA...WITH ITS AXIS EXTENDING SOUTHWESTWARD TO THE MONTANA/NORTH DAKOTA BORDER. A WIDE AREA OF STRATUS CLOUDS WAS SITUATED ON THE WESTERN AND SOUTHERN FRINGES OF THE ARCTIC HIGH. THE STRATUS CLOUDS EXTENDED FROM NORTHERN ALBERTA/SASKATCHEWAN ACROSS NORTHEASTERN MONTANA...ALL OF NORTH DAKOTA...MOST OF MINNESOTA AND SOUTH DAKOTA...AND THE LEADING EDGE OF THE SOUTHERNMOST EXTENT WAS NOSING INTO NORTHEASTERN NEBRASKA. THE MAIN FORECAST CHALLENGES TODAY ARE SKY COVER AND TEMPERATURES. THE STRATUS CLOUDS HAVE INHIBITED RADIATIONAL COOLING DURING THE NIGHTTIME HOURS...AND THINK THE MORNING LOW TEMPERATURES OVER WESTERN AND CENTRAL NORTH DAKOTA WILL BE HIGHER THAN FORECAST. THE ARCTIC HIGH IS FORECAST TO MOVE EAST/SOUTHEAST TODAY...SUCH THAT THE HIGH AXIS WOULD CROSS THE STATE WEST-TO-EAST AND THE AXIS WOULD LIE ACROSS MINNESOTA/IOWA BY THIS EVENING...THEN CONTINUE MOVING SOUTHEAST TOWARDS THE OHIO VALLEY TONIGHT. THERE IS MUCH UNCERTAINTY IN HOW LONG THE STRATUS CLOUDS MAY LINGER IN NORTH DAKOTA. THE MODELS ARE SUGGESTING THE STRATUS REMAINING WELL-ENTRENCHED OVER THE STATE FOR THE MORNING HOURS...THEN BEGIN ERODING FROM THE SOUTH THIS AFTERNOON AS WINDS SWITCH FROM NORTHWEST TO SOUTHEAST AFTER THE HIGH AXIS MOVES THROUGH. HOWEVER...CONFIDENCE IS LOW WHETHER CLOUDS WILL ERODE MUCH. THERE IS SUCH A WIDE SWATH OF CLOUDS ASSOCIATED WITH THE WESTERN AND SOUTHERN PORTIONS OF THE ARCTIC AIRMASS/HIGH...THAT AM THINKING ANY EROSION OF THE CLOUDS IN SOUTHERN NORTH DAKOTA WOULD BE SHORT-LIVED...AND CLOUDS WOULD RETURN DURING THE EVENING HOURS AS FORECAST LOW LEVEL MOISTURE FIELDS ARE VERY HIGH IN THE MODELS. EVEN THIS IS SUSPECT...BECAUSE WARM ADVECTION SHOULD BE TAKING PLACES FROM WEST TO EAST AS THE ARCTIC HIGH EXITS THE REGION. ALL OF THE UNCERTAINTY IN CLOUD COVER WILL IMPACT BOTH FORECAST MAX TEMPERATURES TODAY AND MIN TEMPERATURES TONIGHT. THE LATEST MODEL CONSENSUS WOULD RESULT IN MAX TEMPERATURES RANGING FROM THE TEENS NORTH CENTRAL TO THE LOWER 30S SOUTHWEST...AND MINIMUM TEMPERATURES TONIGHT RANGING FROM AROUND 5 ABOVE IN THE TURTLE MOUNTAINS TO AROUND 20 IN THE FAR SOUTHWEST. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 419 AM CST THU NOV 28 2013 THE MAIN HIGHLIGHT IN THE LONG TERM FORECAST PERIOD CONTINUES TO BE THE POTENTIAL FOR A PROLONGED PERIOD OF SEVERE WINTER WEATHER FROM SUNDAY THROUGH THE MIDDLE OF NEXT WEEK. WILL STRESS AT THE GET-GO THAT FORECAST UNCERTAINTY REMAINS HIGH AND CONFIDENCE BELOW AVERAGE...ESPECIALLY MONDAY-WEDNESDAY. THE EXTENDED PERIOD BEGINS FRIDAY MORNING WITH RELATIVELY WEAK NORTHWEST FLOW ALOFT. AN EMBEDDED S/WV WILL BE MOVING EAST- SOUTHEAST ACROSS NORTHERN SASKATCHEWAN/MANITOBA...WITH AN ASSOCIATED SFC TROUGH AXIS APPROACHING THE FAR WESTERN DAKOTAS. EXTENSIVE AREA OF LOW STRATUS CURRENTLY OVER THE REGION THIS THURSDAY MORNING IS PROJECTED TO STILL HAVE SOME REMNANTS ALONG TO AHEAD OF THIS BOUNDARY FRIDAY MORNING...SLOWLY ERODING WEST TO EAST AND ACROSS THE SOUTHERN EXTENT AS THE FRONTAL BOUNDARY MOVES ACROSS THE WEST AND CENTRAL PORTIONS OF THE STATE AS THE DAY PROGRESSES. EXPECT A MAINLY DRY FROPA WITH MAINLY A MODERATE TO HIGH PERCENT OF CLOUD COVER THE MAIN RESULT INTO FRIDAY NIGHT. CAA FRIDAY NIGHT INTO SATURDAY WITH WEAK HIGH PRESSURE DEVELOPING ACROSS THE REGION. DESPITE SOME CLOUD COVER...SATURDAY IS SHAPING UP TO BE AN OVERALL PLEASANT LATE-FALL DAY WITH A WEAK SFC PRESSURE GRADIENT RESULTING IN LIGHT WINDS AND TEMPERATURES SEASONABLE AROUND 30 NORTH TO THE LOWER 40S SOUTHWEST. NOT A BAD DAY TO WRAP UP OUTSIDE HOUSE WORK OR FINISH CHRISTMAS DECORATING CONSIDERING WHAT IS IN STORE FOR US NEXT WEEK. UPPER LEVEL LOW PRESSURE CURRENTLY SPINNING OVER ALASKA IS FORECAST TO PROPAGATE SOUTHEAST ALONG THE BRITISH COLUMBIA COAST SATURDAY NIGHT INTO SUNDAY NIGHT...POSITIONED OVER THE PACIFIC NORTHWEST BY MONDAY MORNING. MODELS HAVE TRENDED A TAD MORE CONSISTENT WITH LEAD S/WV APPROACHING AND MOVING THROUGH THE NORTHERN PLAINS SUNDAY MORNING - SUNDAY NIGHT...ALONG WITH INCREASING THERMAL UPGLIDE OVER THE WEST AND CENTRAL PORTIONS OF THE STATE SUNDAY DAYTIME WITH A LEE SIDE SFC TROUGH TAKING SHAPE JUST OFF TO OUR WEST OVER THE NORTHERN HIGH PLAINS OF MT/WY. 00Z BUFFER DATA IS INDICATING THERE MAY BE ENOUGH ABOVE FREEZING MID LEVEL AIR SUNDAY/SUNDAY NIGHT ACROSS THE SOUTHWEST FOR MIXED PRECIPITATION WITH SUB-FREEZING SFC TEMPERATURES FORECAST. ELSEWHERE THE PRECIP TYPE SHOULD BE ALL SNOW. GENERALLY LIGHT QPF WITH THIS FIRST WAVE OF OVERRUNNING PRECIPITATION. WILL NOT GET INTO DETAILS MONDAY-WEDNESDAY WITH STILL A WIDE VARIETY OF SOLUTIONS ON THE EVENTUAL EVOLUTION OF THE PACIFIC NORTHWEST LOW. THE 00Z GFS REMAINS MUCH MORE PROGRESSIVE AT FIRST MONDAY AND TUESDAY WITH THE EASTWARD EXTENT OF THE LOW AND THE LARGE SIZE OF CYCLONIC CIRCULATION...THEN MORPHING INTO A SPLIT FLOW REGIME TUESDAY NIGHT - WED. THE LAST TWO RUNS (12Z ON THE 27TH AND 00Z ON THE 28TH) OF THE ECMWF ARE MUCH LESS PROGRESSIVE...MAINTAINING A CLOSED SYSTEM THROUGH WEDNESDAY NIGHT OVER THE INTERMOUNTAIN WEST AND NORTHERN U.S. ROCKIES. THE 12Z RUN MAINTAINED A CLOSED SYSTEM THROUGH THE WORKWEEK...WHILE THE LATEST 00Z RUN OF THE ECMWF NOW DEVELOPS SPLIT FLOW BY THURSDAY. EMBEDDED ENERGY EJECTING OUT OF THIS FEATURE IMPOSSIBLE AT THIS TIME TO ACCURATELY TIME OR TRACK SO LEANED ON ALLBLEND GUIDANCE WITH ZERO EDITS FROM ITS OUTPUT DAYS 5-8. WILL MENTION THAT THE LAST TWO ECMWF RUNS DO INDICATE HIGH QPF ACROSS SOUTH DAKOTA INTO SOUTHERN NORTH DAKOTA BEGINNING TUESDAY NIGHT AND ENDING SOMETIME THURSDAY. WITH THE COLD PROFILE ADVERTISED WOULD SEE SIGNIFICANT SNOW ACCUMULATIONS BASED ON THESE TWO MODEL OUTPUTS ALONG TO SOUTH OF I-94. WILL CONTINUE TO MONITOR. & .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 419 AM CST THU NOV 28 2013 LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS SHOW MVFR CIGS ACROSS ALL OF NORTH DAKOTA EARLY THIS MORNING. EXPECT ALL AERODROMES TO REMAIN MVFR THROUGH SUNRISE. CIGS SHOULD BEGIN TO IMPROVE TO VFR DURING THE LATE AFTERNOON OR EARLY EVENING HOURS ON THURSDAY. THERE IS MUCH UNCERTAINTY FOR WHEN/IF/TIMING OF MVFR CLOUDS SCATTERING OUT DURING THE DAYLIGHT HOURS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 646 AM CST THU NOV 28 2013 LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS SHOW MVFR CIGS ACROSS ALL OF NORTH DAKOTA EARLY THIS MORNING. EXPECT ALL AERODROMES TO REMAIN MVFR THROUGH SUNRISE. CIGS SHOULD BEGIN TO IMPROVE TO VFR DURING THE LATE AFTERNOON OR EARLY EVENING HOURS ON THURSDAY. THERE IS MUCH UNCERTAINTY FOR WHEN/IF/TIMING OF MVFR CLOUDS SCATTERING OUT DURING THE DAYLIGHT HOURS. AFTER 00Z LOWER LEVEL CIGS EXPECTED TO REDEVELOP WITH MVFR CIGS AFTER 03Z. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...NH SHORT TERM...JV LONG TERM...NH AVIATION...JV
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
641 AM CST THU NOV 28 2013 .UPDATE... ISSUED AT 641 AM CST THU NOV 28 2013 CLOUDS CONTINUE TO BE A CHALLENGE. RAP/HRRR CIG GUIDANCE INITIALIZES WITH CLEAR SKIES...BUT THEN DEVELOPS LOW CIGS DURING THE AFTERNOON HOURS (LIKELY CU...LOW CONVECTIVE TEMPS) WHICH GET TRAPPED UNDER THE RIDGE TONIGHT. RAP 925MB-850MB RH FIELD ACTUALLY INDICATES THE DRYING THAT IS WORKING THROUGH THE VALLEY...AND PROBABLY IS CLOSEST TO THE TRUTH. ADJUSTED THE SKY GRIDS FOR CURRENT OBSERVATIONS AND LATEST RAP 925MB-850MB RH. NO MAJOR CHANGES YET UNTIL MORE CONFIDENCE CAN BE OBTAINED WITH WHAT EVER THE CLOUDS WILL DO TODAY. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 300 AM CST THU NOV 28 2013 NORTHWEST FLOW ALOFT WILL CONTINUE INTO FRIDAY...WITH ANOTHER SHORTWAVE EXPECTED FRIDAY INTO FRIDAY NIGHT. 00Z MODELS INDICATE THAT THIS NEXT SHORTWAVE WILL TRACK FURTHER NORTH THAN THE ONE YESTERDAY...KEEPING ACCUMULATING SNOWFALL OUTSIDE OF THE FA. FOR TODAY...THE REGION WILL BE BETWEEN SHORTWAVES AS HIGH PRESSURE BUILDS FROM THE NORTH. THIS WILL LEAVE CLOUD TRENDS AS THE MAIN CHALLENGE. 09Z SATELLITE IMAGERY SHOWS CLEARING WORKING INTO THE NORTHERN VALLEY. MODELS ARE STRUGGLING WITH THE CURRENT CLOUD COVER...ALTHOUGH THE 07Z RAP IS CLOSEST WHEN LOOKING AT THE 925MB- 850MB RH FIELD. THIS MODEL INDICATES THAT CLEARING WILL CONTINUE TO MOVE DOWN THE VALLEY...WITH CLOUDS DISSIPATING ALONG BOTH EDGES THROUGH THE DAY. THIS SCENARIO MAKES SOME SENSE WITH THE HIGH BUILDING INTO THE REGION. HOWEVER...CONVECTIVE TEMPS WILL BE IN THE TEENS UNTIL LATE AFTERNOON...WHICH COULD LEAD TO REDEVELOPMENT WITHIN CLEARING AREAS. DID DELAY THE CLEARING...BUT REMAINED OPTIMISTIC THAT MOST AREAS WILL CLEAR THIS AFTERNOON. ALSO...CONSIDERING CURRENT CONDITIONS...MENTIONED FLURRIES WITHIN EXPECTED CLOUDY AREAS. MIN TEMPS TONIGHT VERY DEPENDENT ON WHETHER OR NOT WE GET RID OF THE CLOUDS TODAY. IF WE DO CLEAR...THERE WILL LIKELY WILL BE A QUICK DROP THIS EVENING BEFORE RETURN FLOW KICKS IN AND TEMPS BECOME STEADY AFTER MIDNIGHT. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 300 AM CST THU NOV 28 2013 FRIDAY NIGHT-SATURDAY NIGHT...HIGH PRESSURE MOVING THROUGH SHOULD LEAD TO DRY WEATHER. NOT SURE ABOUT CLOUD COVER (CONSIDERING CURRENT CONDITIONS FOLLOWING A SHORTWAVE). CURRENT THOUGHT IS THAT SINCE THE FRIDAY SHORTWAVE WILL TRACK FURTHER NORTH THAN THE CURRENT SYSTEM...SHOULD BE LESS CLOUDS. ALSO...ANTICIPATE A WARMER AIRMASS. SUNDAY-WEDNESDAY...DETERMINISTIC MODEL RUNS CONTINUE TO SUGGEST A MORE ACTIVE PATTERN TAKING SHAPE NEXT WEEK AS AN UPPER WAVE CURRENTLY ACROSS ALASKA DIVES SOUTHWARD INTO THE WESTERN CONUS DURING THE FIRST HALF OF NEXT WEEK...WITH ZONAL FLOW TRANSITIONING TO SOUTHWEST FLOW ALOFT DOWNSTREAM ACROSS THE PLAINS. 00Z MODELS SUGGEST THE POTENTIAL FOR SOME LIGHT SNOW WITH WARM ADVECTION LATER SUNDAY INTO MONDAY. BEYOND THIS POINT...CONFIDENCE REGARDING ANY PARTICULAR DETAILS IS VERY LOW...WITH SIGNIFICANT DIFFERENCES AMONG MODELS IN HANDLING THE UPPER LONGWAVE TROUGH AND TIMING/PLACEMENT OF EMBEDDED SHORTWAVE TROUGHS. THE LOW TO MID-LEVEL BAROCLINIC ZONE WILL REMAIN POSITIONED ACROSS THE NORTHERN PLAINS THROUGH MID-WEEK BEFORE ADVANCING SOUTHWARD. ANY WAVE EJECTING OUT OF THE BROADER TROUGH TO THE WEST ALONG THIS BAROCLINIC ZONE WILL NEED TO BE WATCHED FOR SFC CYCLONE DEVELOPMENT...WITH THE 00Z ECMWF INDICATING A MORE SIGNIFICANT WAVE FOR THE MIDDLE OF THE WEEK. GIVEN THE VARIED MODEL SOLUTIONS...CONTINUED WITH BROADBRUSHED SLIGHT/CHANCE POPS THROUGH MUCH OF THE PERIOD. TEMPS THROUGH MID-WEEK LOOK TO BE SEASONABLE BEFORE COLDER AIR ARRIVES LATE IN THE WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 641 AM CST THU NOV 28 2013 LOW CONFIDENCE FORECAST FOR TODAY AS GUIDANCE IS PERFORMING POORLY WITH THE CURRENT SITUATION. THE MOST LIKELY SCENARIO IS THAT MVFR CIGS WILL REMAIN WEST OF THE VALLEY THROUGH MUCH OF THE DAY...BREAKING UP BY THIS EVENING. SKY WITHIN THE VALLEY (KGFK/KFAR) IS CURRENTLY CLEAR...AND SHOULD REMAIN THAT WAY (WITH A BRIEF PERIOD OF MVFR CU DEVELOPMENT MID-DAY). ANTICIPATE CLEARING EAST OF THE VALLEY BY EARLY TO MID AFTERNOON. WILL AMEND THE TAFS IF MORE CONFIDENCE CAN BE OBTAINED. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...TG SHORT TERM...TG LONG TERM...TG/MAKOWSKI AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
300 AM CST THU NOV 28 2013 .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 300 AM CST THU NOV 28 2013 NORTHWEST FLOW ALOFT WILL CONTINUE INTO FRIDAY...WITH ANOTHER SHORTWAVE EXPECTED FRIDAY INTO FRIDAY NIGHT. 00Z MODELS INDICATE THAT THIS NEXT SHORTWAVE WILL TRACK FURTHER NORTH THAN THE ONE YESTERDAY...KEEPING ACCUMULATING SNOWFALL OUTSIDE OF THE FA. FOR TODAY...THE REGION WILL BE BETWEEN SHORTWAVES AS HIGH PRESSURE BUILDS FROM THE NORTH. THIS WILL LEAVE CLOUD TRENDS AS THE MAIN CHALLENGE. 09Z SATELLITE IMAGERY SHOWS CLEARING WORKING INTO THE NORTHERN VALLEY. MODELS ARE STRUGGLING WITH THE CURRENT CLOUD COVER...ALTHOUGH THE 07Z RAP IS CLOSEST WHEN LOOKING AT THE 925MB- 850MB RH FIELD. THIS MODEL INDICATES THAT CLEARING WILL CONTINUE TO MOVE DOWN THE VALLEY...WITH CLOUDS DISSIPATING ALONG BOTH EDGES THROUGH THE DAY. THIS SCENARIO MAKES SOME SENSE WITH THE HIGH BUILDING INTO THE REGION. HOWEVER...CONVECTIVE TEMPS WILL BE IN THE TEENS UNTIL LATE AFTERNOON...WHICH COULD LEAD TO REDEVELOPMENT WITHIN CLEARING AREAS. DID DELAY THE CLEARING...BUT REMAINED OPTIMISTIC THAT MOST AREAS WILL CLEAR THIS AFTERNOON. ALSO...CONSIDERING CURRENT CONDITIONS...MENTIONED FLURRIES WITHIN EXPECTED CLOUDY AREAS. MIN TEMPS TONIGHT VERY DEPENDENT ON WHETHER OR NOT WE GET RID OF THE CLOUDS TODAY. IF WE DO CLEAR...THERE WILL LIKELY WILL BE A QUICK DROP THIS EVENING BEFORE RETURN FLOW KICKS IN AND TEMPS BECOME STEADY AFTER MIDNIGHT. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 300 AM CST THU NOV 28 2013 FRIDAY NIGHT-SATURDAY NIGHT...HIGH PRESSURE MOVING THROUGH SHOULD LEAD TO DRY WEATHER. NOT SURE ABOUT CLOUD COVER (CONSIDERING CURRENT CONDITIONS FOLLOWING A SHORTWAVE). CURRENT THOUGHT IS THAT SINCE THE FRIDAY SHORTWAVE WILL TRACK FURTHER NORTH THAN THE CURRENT SYSTEM...SHOULD BE LESS CLOUDS. ALSO...ANTICIPATE A WARMER AIRMASS. SUNDAY-WEDNESDAY...DETERMINISTIC MODEL RUNS CONTINUE TO SUGGEST A MORE ACTIVE PATTERN TAKING SHAPE NEXT WEEK AS AN UPPER WAVE CURRENTLY ACROSS ALASKA DIVES SOUTHWARD INTO THE WESTERN CONUS DURING THE FIRST HALF OF NEXT WEEK...WITH ZONAL FLOW TRANSITIONING TO SOUTHWEST FLOW ALOFT DOWNSTREAM ACROSS THE PLAINS. 00Z MODELS SUGGEST THE POTENTIAL FOR SOME LIGHT SNOW WITH WARM ADVECTION LATER SUNDAY INTO MONDAY. BEYOND THIS POINT...CONFIDENCE REGARDING ANY PARTICULAR DETAILS IS VERY LOW...WITH SIGNIFICANT DIFFERENCES AMONG MODELS IN HANDLING THE UPPER LONGWAVE TROUGH AND TIMING/PLACEMENT OF EMBEDDED SHORTWAVE TROUGHS. THE LOW TO MID-LEVEL BAROCLINIC ZONE WILL REMAIN POSITIONED ACROSS THE NORTHERN PLAINS THROUGH MID-WEEK BEFORE ADVANCING SOUTHWARD. ANY WAVE EJECTING OUT OF THE BROADER TROUGH TO THE WEST ALONG THIS BAROCLINIC ZONE WILL NEED TO BE WATCHED FOR SFC CYCLONE DEVELOPMENT...WITH THE 00Z ECMWF INDICATING A MORE SIGNIFICANT WAVE FOR THE MIDDLE OF THE WEEK. GIVEN THE VARIED MODEL SOLUTIONS...CONTINUED WITH BROADBRUSHED SLIGHT/CHANCE POPS THROUGH MUCH OF THE PERIOD. TEMPS THROUGH MID-WEEK LOOK TO BE SEASONABLE BEFORE COLDER AIR ARRIVES LATE IN THE WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1148 PM CST WED NOV 27 2013 MVFR CIGS CONTINUE TO REMAIN WEST OF THE RED RIVER VALLEY AND CONTINUE TO MOVE SOUTH FROM WEST AND CENTRAL ND. WILL GENERALLY KEEP VFR CIGS ACROSS THE AREA EXCEPT FOR THE EAST/NORTHEAST ZONES. LIGHT SNOW SHOULD LOWER CIGS AND VISIBILITIES IN THE NORTHEAST ZONES. LOW LEVEL RH GETS TO BE A THIN LAYER BY THU AFTERNOON. WILL SCATTER CLOUDS OUT AROUND THE NOON HOUR. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ SHORT TERM...TG LONG TERM...TG/MAKOWSKI AVIATION...HOPPES
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1236 AM CST THU NOV 28 2013 .UPDATE... ISSUED AT 1236 AM CST THU NOV 28 2013 STRATUS CLOUDS COVERED ALL BUT THE EXTREME SOUTHWESTERN CORNER OF THE STATE...AND THE TREND IN SATELLITE LOOP INDICATES THE SOUTHWEST CORNER SHOULD SOON BE CLOUDY. THE LOW PRESSURE CENTER ASSOCIATED WITH THE COLD FRONT THAT MOVED THROUGH THE STATE WEDNESDAY WAS WELL TO THE SOUTHEAST...FROM MINNESOTA/IOWA TO SOUTHERN NEBRASKA AND NORTHWEST WINDS CONTINUED ACROSS NORTH DAKOTA. THE ARCTIC HIGH WAS CENTERED OVER NORTHERN MANITOBA WITH ITS AXIS EXTENDING SOUTHWESTWARD ACROSS SOUTHERN SASKATCHEWAN AND INTO THE MONTANA/NORTH DAKOTA BORDER. SKIES SHOULD REMAIN CLOUDY FOR THE REST OF THE NIGHTTIME HOURS...BUT THERE IS UNCERTAINTY AS TO WHEN/IF/WHERE THE LOW CLOUDS WILL SCATTER DURING THE DAYLIGHT HOURS ON THANKSGIVING DAY. ONLY ADJUSTMENTS WERE TO THE HOURLY TEMPERATURE/DEWPOINT TRENDS. OTHERWISE CURRENT FORECAST ON TRACK. UPDATE ISSUED AT 924 PM CST WED NOV 27 2013 LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS CONTINUE TO SHOW WESTERN AND CENTRAL NORTH DAKOTA INUNDATED WITH STRATUS. ISOLATED FLURRIES CONTINUE IN THE NORTH. ONLY ADJUSTMENT WAS TO RAISE OVERNIGHT TEMPERATURES BETWEEN 3 AND 5 DEGREES DUE TO THE CLOUDS AND MIXED BOUNDARY LAYER/BRISK WINDS. LATEST NAM AND RAP13 SHOWS THE STRATUS CONTINUING THROUGH 18Z THURSDAY...AND POSSIBLY INTO THE AFTERNOON. UPDATE ISSUED AT 556 PM CST WED NOV 27 2013 MAIN UPDATE THIS EVENING WAS TO INCREASE SKY GRIDS TO 100 PERCENT OVER MOST OF WESTERN AND CENTRAL NORTH DAKOTA. LATEST FOG/STRATUS LOOP IN CONJUNCTION WITH THE RAP13 AND HRRR 925MB-H85 RH FIELD...ARE VERIFYING WELL AND ARE IN GOOD AGREEMENT TONIGHT. THE STRATUS WILL MAKE IT TO THE SOUTHERN BORDER IN THE NEXT FEW HOURS AS WELL AS INTO THE JAMES RIVER VALLEY. EXPECT OVERCAST CONDITIONS WITH ISOLATED FLURRIES TONIGHT INTO MID MORNING THURSDAY BEFORE SKY IMPROVEMENTS BEGIN. REST OF FORECAST IS ON TRACK. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 352 PM CST WED NOV 27 2013 THE TEMPERATURE ROLLER COASTER WILL CONTINUE TONIGHT AND THURSDAY AS ANOTHER SHOT OF COLD CANADIAN AIR PUSHES SOUTH INTO NORTH DAKOTA. LOW STRATUS HAS ADVANCED INTO FAR NORTHWEST ND DURING THE EARLY AFTERNOON...AND WILL CONTINUE A SOUTHWARD PUSH...ACCOMPANIED BY A FEW FLURRIES. EXPECT ANOTHER NIGHT OF LOWS IN THE SINGLE DIGITS TO TEENS SOUTHWEST. ON THANKSGIVING DAY...HIGH PRESSURE WILL DRIFT INTO EASTERN NORTH DAKOTA ON THURSDAY...SETTING UP ANOTHER NE-SW TEMPERATURE GRADIENT. HIGHS ARE FORECAST IN THE MID TEENS NEAR THE TURTLE MOUNTAINS...LOW TO MID 20S NEAR BISMARCK/MANDAN...AND NEAR 30 AT BOWMAN. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 352 PM CST WED NOV 27 2013 POTENTIAL MAJOR WINTER STORM NEXT WEEK. THE MAIN FOCUS THROUGH THE EXTENDED PERIOD IS ON A POTENTIAL WINTER STORM THAT MAY IMPACT THE REGION SUNDAY THROUGH THURSDAY. AT THIS TIME THERE IS A LOT OF UNCERTAINTY AS TO TIMING...PLACEMENT AND AMOUNTS. MODEL RUNS HAVE SLOWLY COME INTO BETTER AGREEMENT OVER THE PAST RUN...BUT THERE ARE STILL LARGE DISCREPANCIES THAT NEED TO BE RESOLVED BEFORE CONFIDENCE CLIMBS HIGH ENOUGH TO WARRANT ANY THOUGHT OF WINTER WEATHER HEADLINES. THE 12 UTC HAS THE POLAR AND SUBTROPICAL JETS PHASING TOGETHER LATE NEXT WEEK AS A VERY POTENT LONGWAVE TROUGH DIGS SOUTH ACROSS THE MOUNTAIN WEST. THIS WOULD SET UP VERY STRONG CYCLOGENESIS ACROSS THE PLAINS. THE ECMWF IS STRONGER AND DEEPER WITH THIS TROUGH AND CYCLOGENESIS AND THEREFORE FURTHER SOUTH AND SLIGHTLY SLOWER THAN THE GFS. THE 12 UTC GFS MAINTAINS SPLIT FLOW UNTIL THE VERY END OF NEXT WEEK AND DEVELOPS MORE OF A PROGRESSIVE OPEN WAVE. THIS WOULD TEND TO FAVOR A QUICKER AND FURTHER NORTH SOLUTION. ONE THING THAT IS MORE CERTAIN IS THE INTRUSION OF COLD AIR. A VERY COLD AIRMASS IS SETTING UP ACROSS EASTERN SIBERIA AND IS PROGGED TO ENTER EASTERN ALASKA AND FROM THERE MAKE A BEELINE TOWARD THE CENTRAL CONTINENTAL USA. THIS COULD POTENTIALLY BE THE COLDEST AIR WE HAVE SEEN YET WITH 850MB TEMPS AROUND -25. UNTIL LATE SUNDAY TEMPERATURES SHOULD BE MILD AND AND PRECIP CHANCES MINIMAL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1236 AM CST THU NOV 28 2013 LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS SHOW MVFR CIGS ACROSS NEARLY ALL OF NORTH DAKOTA EARLY THIS MORNING. EXPECT ALL AERODROMES TO REMAIN MVFR THROUGH SUNRISE. CIGS SHOULD BEGIN TO IMPROVE TO VFR DURING THE LATE AFTERNOON OR EARLY EVENING HOURS ON THURSDAY. THERE IS MUCH UNCERTAINTY FOR WHEN/IF/TIMING OF MVFR CLOUDS SCATTERING OUT DURING THE DAYLIGHT HOURS. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JV SHORT TERM...RK LONG TERM...AJ AVIATION...JV
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1150 AM CST THU NOV 28 2013 .UPDATE... ISSUED AT 949 AM CST THU NOV 28 2013 CLOUDS ARE PROVIDING THE GREATEST CHALLENGE FOR THE SHORT TERM TODAY. FAIRLY EXTENSIVE CLOUDS PRESENT EARLY THIS MORNING HAVE DIMINISHED IN COVERAGE EAST...BUT ARE FAIRLY SOLID FOR THE TIME WEST. BASED ON KABR/KBIS MORNING RAOBS...THESE CLOUDS ARE FAIRLY SHALLOW...BUT IMPRESSIVELY TRAPPED BELOW INVERSION...MAKING THE DISSIPATION LIKELY TO BE A RESULT OF DRYING AND LIMITED HEATING BELOW INVERSION AS WELL AS AN ADVECTIVE COMPONENT. RAP ON THE RIGHT TRACK...BUT TOO PESSIMISTIC TOWARD I 29 CORRIDOR. AT THIS TIME... CLOUDS LOOK TO BE FAIRLY TOUGH TO SHAKE IN THE WEST/SOUTHWEST CWA WHILE THOSE AREAS IN ADVANCE OF THE LOW LEVEL RIDGE AXIS FROM AROUND I29 EASTWARD ARE CERTAIN TO FIND A MIX OF CLOUDS AND SUN THROUGH MIDDAY AND THEN TRENDING TOWARD MORE SUN. BASED ON TEMPS ON CLOUD BEARING LEVEL AS WELL AS UPSTREAM OBSERVATIONS...HAVE ADDED IN A FEW FLURRIES TO AREAS AS FAR SOUTH AS AROUND KFSD...BUT EXPECT STRONGER COVERAGE OF LOW REFLECTIVITIES ON KABR RADAR TO DWINDLE SOMEWHAT WITH INCREASING DISTANCE FROM WEAK TERRAIN SUPPORT. EARLIER FLURRIES IN SW MN COULD HAVE IMPACTED SOMEWHAT MORE RAPID DISSIPATION IN CLOUDS...AND MAY ALSO INFLUENCE THE CLEARING TREND. TEMPS ALSO CHALLENGING WITH CONTINUED LOW LEVEL COLD AIR ADVECTION...BUT TEMPS ALREADY REACHING INDICATED MIXING POTENTIAL UNDER CLOUDY AREAS BY MID MORNING. PROBABLY NOT MUCH ROOM TO WARM MORE THAN A FEW DEGREES ANYWHERE TODAY...MOST SO IN AREAS WITH SUNSHINE TO THE EAST. UPDATES OUT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 520 AM CST THU NOV 28 2013 CURRENT SURFACE ANALYSIS SHOWS THE FRONTAL BOUNDARY HAVING PUSHED THROUGH OUR CWA EARLY THIS MORNING...WITH AN AREA OF STRATUS STREAMING INTO OUR WESTERN CWA BEHIND THE EXITING SYSTEM. THE SURFACE RIDGE AXIS PRESENTLY LOCATED THROUGH THE WESTERN PORTIONS OF THE DAKOTA WILL SLIDE TO THE SOUTH AND EAST TODAY...AND WITH DRYING AND SUBSIDENCE LOOKING FOR THE LOW CLOUDS TO THIN OUT ACROSS THE AREA BY LATE MORNING OR EARLY AFTERNOON. OTHERWISE...IT WILL BE BREEZY DURING THE EARLY PART OF THE DAY...ESPECIALLY IN THE EAST...WITH COLD AIR ADVECTION AND A DECENT GRADIENT ACROSS THE AREA...THEN TAPERING DOWN IN THE AFTERNOON AS HIGH PRESSURE BUILDS IN AND THE GRADIENT RELAXES AND ML WINDS DECREASE. THERMAL PROFILES DO COOL A BIT TODAY...THOUGH NOTHING TOO EXTREME WITH HIGHS STILL MAKING IT INTO THE MID 20S TO LOWER 30S FROM NORTHEAST TO SOUTHWEST RESPECTIVELY. THE HIGH PRESSURE MOVES QUICKLY TO THE EAST TONIGHT...AND WITH THAT WINDS WILL TRANSITION TO SOUTHEASTERLY AND PICK UP LATER AT NIGHT. IT WILL STILL BE A COLD NIGHT WITH LOWS IN THE UPPER SINGLE DIGITS TO TEENS...WITH TEMPS STEADYING OUT OR RISING SOME LATE AT NIGHT AS THE WINDS INCREASE. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 520 AM CST THU NOV 28 2013 POTENT PACIFIC LOW DIVES INTO THE PACIFIC NORTHWEST FRIDAY AND SATURDAY...SHIFTING THE INTERMOUNTAIN WEST RIDGING ITO THE PLAINS STATES. A STRONG PUSH OF WARM AIR ADVECTION AND BREEZY SOUTHERLY WINDS WILL BRING MILDER TEMPERATURES ON FRIDAY DESPITE SOME PASSING MID AND HIGH CLOUDS FILTERING THE SUNSHINE. HIGHS WILL WARM TO SLIGHTLY ABOVE NORMAL READINGS IN THE LOW 30S EAST TO THE MID 40S WEST. A WEAK FRONT SAGS ACROSS THE FORECAST AREA FRIDAY NIGHT THROUGH SATURDAY MORNING...BUT WITHOUT MOISTURE OR A REAL COLD AIR PUSH BEHIND IT...CONDITIONS WILL REMAIN DRY AND MILD WITH HIGHS MIXING INTO THE UPPER 30S TO MID 40S. MUCH GREATER UNCERTAINTY SHOWS UP EARLY NEXT WEEK AS THE PACIFIC TROUGH STRENGTHENS AND MOVES INTO THE NORTHERN ROCKIES. MODELS STILL SHOWING SIGNIFICANT DIFFERENCES IN THE STRENGTH...TIMING AND TRACK OF THE UPPER LOW. THE GFS FOLLOWS A MORE NORTHERLY TRACK WHILE THE ECMWF IS SLOWER AND FURTHER SOUTH. FINALLY...THE CANADIAN DEPICTS A MUCH WEAKER SYSTEM OVERALL WHICH GIVEN THE ENERGETIC NATURE OF THIS SYSTEM SEEMS THE LEAST LIKELY. INITIAL SHORTWAVE AHEAD OF THE MAIN SYSTEM SLIDES SOUTHEAST ACROSS THE REGION AROUND THE SUNDAY NIGHT/MONDAY TIME FRAME. WITH THE GFS RAPIDLY AMPLIFYING THE PAC NW TROUGH AND UPPER RIDGE AHEAD OF IT...THIS WAVE IS WEAKER AND FASTER MOVING THAN THE ECMWF WHICH DEVELOPS AN INVERTED TROUGH FEATURE OVER THE NORTHERN AND CENTRAL PLAINS AND KEEPS IT IN THE PICTURE WELL INTO TUESDAY. SIGNIFICANT DIFFERENCES IN TEMPERATURE PROFILES ALSO MAKE PRECIPITATION TYPES DIFFICULT TO PINPOINT. TEMPERATURES LOOK TO REMAIN SEASONALLY MILD THROUGH WEDNESDAY WITH MUCH COOLER READINGS ARRIVING LATE IN THE WEEK. FOR NOW WILL KEEP MENTION OF BOTH RAIN AND SNOW. NOT MUCH CONFIDENCE IN THE TIMING OF THE PRECIPITATION BUT CHANCES DO APPEAR TO IMPROVE AS WE MOVE TOWARDS MID WEEK AS THE MAIN PACIFIC TROUGH ADVANCES TOWARDS THE REGION. FOR NOW DID NOT ALTER THE ALLBLEND POPS OR TEMPS MUCH GIVEN SUCH UNCERTAINTY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1149 AM CST THU NOV 28 2013 MVFR CEILINGS WILL CONTINUE ACROSS MUCH OF THE AREA EARLY THIS AFTERNOON... BUT SHOULD GRADUALLY SEE COVERAGE BEGIN TO FAVOR AREAS WEST OF THE JAMES RIVER VALLEY AFTER 21Z. REMAINDER OF THE PERIOD SHOULD BE VFR...WITH EXCEPTION OF THOSE CEILINGS HANGING UP IN THE FAR WEST. AT THIS POINT...IT IS ANTICIPATED THAT MOST OF THE CEILINGS WILL DISSIPATE BEFORE RETURNING EASTWARD EARLY FRIDAY...BUT COULD HAVE TO WATCH KHON FOR SOME MVFR CLOUDS AGAIN BY AROUND 15Z. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ UPDATE...CHAPMAN SHORT TERM... LONG TERM...JM AVIATION...CHAPMAN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1123 AM CST THU NOV 28 2013 .UPDATE... SEE UPDATED AVIATION DISCUSSION BELOW. THE MAIN FORECAST CHANGES THIS MORNING REVOLVE AROUND THE STRATUS DECK THAT HAS SPREAD OVER THE REGION. MODELS ARE MUCH TO OPTIMISTIC IN ERODING THE CLOUD DECK...SO ADJUSTED THE SKY GRIDS TO KEEP THE WESTERN HALF OF THE CWA UNDER CLOUD COVER MUCH LONGER THAN ORIGINALLY ANTICIPATED. ALSO EXTENDED THE FLURRIES MENTION AS SEVERAL OBS HAVE REPORTED VERY LIGHT SNOW THIS MORNING. OVERALL THE OTHER FORECAST FIELDS SEEM TO BE ON TRACK...TEMPERATURES WILL REMAIN PRETTY STEADY THROUGH THE DAY...AND THE INHERITED FORECAST TREND SEEMS TO BE REFLECTING THIS WELL. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH SATURDAY AN EXTENSIVE STRATUS DECK OVER THE REGION IS KEEPING TEMPERATURES RELATIVELY MILD WITH CURRENT READINGS IN THE MID 20S. BASED ON THE PAST FEW RUNS OF THE RUC...IT SEEMS UNLIKELY THIS STRATUS DECK WILL DISSIPATE ANYTIME SOON. WOULD NOT BE TOO SURPRISED IF THESE CLOUDS HANG AROUND THROUGH THIS AFTERNOON BEFORE DRIER AIR AT 925 MB MOVES IN FROM THE SOUTHWEST. OF COURSE THESE CLOUDS WILL MAKE FORECASTING HIGH TEMPERATURES RATHER DIFFICULT. HAVE RELIED UPON THE RUC MODEL WHICH SHOWS A SLIGHT COOL DOWN AROUND SUNRISE...THEN A SLIGHT INCREASE BY 21Z. HIGH PRESSURE SHIFTS EAST OF THE REGION TONIGHT...ALLOWING WAA TO SPREAD ACROSS THE WESTERN CWA WHERE TEMPERATURES SHOULD BECOME STEADY OR SLOWLY RISE AFTER MIDNIGHT. ANOTHER WEAK LOW PRESSURE SYSTEM PASSING ACROSS THE REGION ON FRIDAY WILL BRING WARM TEMPERATURES BACK INTO THE AREA. TEMPS AT 925/850 MB ARE PROJECTED TO RANGE AROUND NORMAL...WHICH WHEN COMBINED WITH DECENT MIXING WINDS SHOULD EQUAL HIGHS IN THE MID 30S...TO THE MID 40S. WOULD NOT BE TOO SURPRISED IF HIGH TEMPERATURES END UP BEING WARMER. SLIGHTLY COOLER LOW LEVEL TEMPERATURES ALONG WITH WEAK CAA ON SATURDAY WILL RESULT IN HIGHS IN THE LOW TO MID 30S. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY LATEST MODEL RUNS CONTINUE TO FORECAST A MAJOR PATTERN SHIFT DURING THE LONG TERM. HOWEVER THE DETAILS REMAIN SKETCHY AS EACH MODEL HAS ITS OWN IDEA ON HOW TO HANDLE ENERGY WITHIN THE DEVELOPING MID LEVEL TROF AND THAT TROFS EVOLUTION THROUGH THE MIDDLE OF NEXT WEEK. THE ECMWF IS BY FAR THE MOST AGGRESSIVE IN SETTING UP A BAROCLINIC ZONE ACROSS THE REGION AND CRANKS OUT COPIOUS AMOUNTS OF PCPN FROM TUESDAY THROUGH THURSDAY. THE GFS IS MORE PROGRESSIVE AND FEATURES A MORE POSITIVE TILT MID LEVEL TROF OVER THE WESTERN/CENTRAL CONUS LEADING TO A LESS INTENSE BAROCLINIC ZONE OVER THE NORTHERN PLAINS. THE LAST COUPLE RUNS OF THE ECMWF HAVE BEEN CONSISTENTLY SLOWER AND WETTER VS THE GFS. BUT IT SEEMS OVERLY WET. NONETHELESS WILL BE AN INTERESTING MIDDLE OF NEXT WEEK WEATHER-WISE WITH A MIXED BAG OF PCPN EXPECTED NO MATTER WHICH MODEL YOU LIKE. TEMPERATURES ARE EXPECTED TO BE ABOVE NORMAL FOR THE FIRST PART OF THE PERIOD...BUT THEN TRANSITION TOWARD NORMAL AS COLDER AIR INVADES FROM CANADA TOWARD MID TO LATE WEEK. && .AVIATION... 18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS MVFR CIGS WILL PREVAIL THIS AFTERNOON AND INTO THE OVERNIGHT HOURS ACROSS THE WESTERN HALF OF THE CWA...INCLUDING KPIR AND KMBG. KABR AND KATY LOOK TO BE RIGHT ON THE EDGE OF THESE CIGS...SO WILL BE IN AND OUT OF THE MVFR CIGS. FROM LATE TONIGHT AND THROUGH THE MORNING HOURS ON FRIDAY...VFR CONDITIONS WILL PREVAIL. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...SERR SHORT TERM...SD LONG TERM...TDK AVIATION...PARKIN WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1035 AM CST THU NOV 28 2013 .UPDATE... THE MAIN FORECAST CHANGES THIS MORNING REVOLVE AROUND THE STRATUS DECK THAT HAS SPREAD OVER THE REGION. MODELS ARE MUCH TO OPTIMISTIC IN ERODING THE CLOUD DECK...SO ADJUSTED THE SKY GRIDS TO KEEP THE WESTERN HALF OF THE CWA UNDER CLOUD COVER MUCH LONGER THAN ORIGINALLY ANTICIPATED. ALSO EXTENDED THE FLURRIES MENTION AS SEVERAL OBS HAVE REPORTED VERY LIGHT SNOW THIS MORNING. OVERALL THE OTHER FORECAST FIELDS SEEM TO BE ON TRACK...TEMPERATURES WILL REMAIN PRETTY STEADY THROUGH THE DAY...AND THE INHERITED FORECAST TREND SEEMS TO BE REFLECTING THIS WELL. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH SATURDAY AN EXTENSIVE STRATUS DECK OVER THE REGION IS KEEPING TEMPERATURES RELATIVELY MILD WITH CURRENT READINGS IN THE MID 20S. BASED ON THE PAST FEW RUNS OF THE RUC...IT SEEMS UNLIKELY THIS STRATUS DECK WILL DISSIPATE ANYTIME SOON. WOULD NOT BE TOO SURPRISED IF THESE CLOUDS HANG AROUND THROUGH THIS AFTERNOON BEFORE DRIER AIR AT 925 MB MOVES IN FROM THE SOUTHWEST. OF COURSE THESE CLOUDS WILL MAKE FORECASTING HIGH TEMPERATURES RATHER DIFFICULT. HAVE RELIED UPON THE RUC MODEL WHICH SHOWS A SLIGHT COOL DOWN AROUND SUNRISE...THEN A SLIGHT INCREASE BY 21Z. HIGH PRESSURE SHIFTS EAST OF THE REGION TONIGHT...ALLOWING WAA TO SPREAD ACROSS THE WESTERN CWA WHERE TEMPERATURES SHOULD BECOME STEADY OR SLOWLY RISE AFTER MIDNIGHT. ANOTHER WEAK LOW PRESSURE SYSTEM PASSING ACROSS THE REGION ON FRIDAY WILL BRING WARM TEMPERATURES BACK INTO THE AREA. TEMPS AT 925/850 MB ARE PROJECTED TO RANGE AROUND NORMAL...WHICH WHEN COMBINED WITH DECENT MIXING WINDS SHOULD EQUAL HIGHS IN THE MID 30S...TO THE MID 40S. WOULD NOT BE TOO SURPRISED IF HIGH TEMPERATURES END UP BEING WARMER. SLIGHTLY COOLER LOW LEVEL TEMPERATURES ALONG WITH WEAK CAA ON SATURDAY WILL RESULT IN HIGHS IN THE LOW TO MID 30S. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY LATEST MODEL RUNS CONTINUE TO FORECAST A MAJOR PATTERN SHIFT DURING THE LONG TERM. HOWEVER THE DETAILS REMAIN SKETCHY AS EACH MODEL HAS ITS OWN IDEA ON HOW TO HANDLE ENERGY WITHIN THE DEVELOPING MID LEVEL TROF AND THAT TROFS EVOLUTION THROUGH THE MIDDLE OF NEXT WEEK. THE ECMWF IS BY FAR THE MOST AGGRESSIVE IN SETTING UP A BAROCLINIC ZONE ACROSS THE REGION AND CRANKS OUT COPIOUS AMOUNTS OF PCPN FROM TUESDAY THROUGH THURSDAY. THE GFS IS MORE PROGRESSIVE AND FEATURES A MORE POSITIVE TILT MID LEVEL TROF OVER THE WESTERN/CENTRAL CONUS LEADING TO A LESS INTENSE BAROCLINIC ZONE OVER THE NORTHERN PLAINS. THE LAST COUPLE RUNS OF THE ECMWF HAVE BEEN CONSISTENTLY SLOWER AND WETTER VS THE GFS. BUT IT SEEMS OVERLY WET. NONETHELESS WILL BE AN INTERESTING MIDDLE OF NEXT WEEK WEATHER-WISE WITH A MIXED BAG OF PCPN EXPECTED NO MATTER WHICH MODEL YOU LIKE. TEMPERATURES ARE EXPECTED TO BE ABOVE NORMAL FOR THE FIRST PART OF THE PERIOD...BUT THEN TRANSITION TOWARD NORMAL AS COLDER AIR INVADES FROM CANADA TOWARD MID TO LATE WEEK. && .AVIATION... 12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS MVFR CIGS ARE EXPECTED TO PERSIST AT LEAST INTO THE AFTERNOON FOR MOST TERMINALS. MOST AREAS SHOULD BECOME VFR BY EVENING. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...SERR SHORT TERM...SD LONG TERM...TDK AVIATION...TDK WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
949 AM CST THU NOV 28 2013 .UPDATE... ISSUED AT 949 AM CST THU NOV 28 2013 CLOUDS ARE PROVIDING THE GREATEST CHALLENGE FOR THE SHORT TERM TODAY. FAIRLY EXTENSIVE CLOUDS PRESENT EARLY THIS MORNING HAVE DIMINISHED IN COVERAGE EAST...BUT ARE FAIRLY SOLID FOR THE TIME WEST. BASED ON KABR/KBIS MORNING RAOBS...THESE CLOUDS ARE FAIRLY SHALLOW...BUT IMPRESSIVELY TRAPPED BELOW INVERSION...MAKING THE DISSIPATION LIKELY TO BE A RESULT OF DRYING AND LIMITED HEATING BELOW INVERSION AS WELL AS AN ADVECTIVE COMPONENT. RAP ON THE RIGHT TRACK...BUT TOO PESSIMISTIC TOWARD I 29 CORRIDOR. AT THIS TIME... CLOUDS LOOK TO BE FAIRLY TOUGH TO SHAKE IN THE WEST/SOUTHWEST CWA WHILE THOSE AREAS IN ADVANCE OF THE LOW LEVEL RIDGE AXIS FROM AROUND I29 EASTWARD ARE CERTAIN TO FIND A MIX OF CLOUDS AND SUN THROUGH MIDDAY AND THEN TRENDING TOWARD MORE SUN. BASED ON TEMPS ON CLOUD BEARING LEVEL AS WELL AS UPSTREAM OBSERVATIONS...HAVE ADDED IN A FEW FLURRIES TO AREAS AS FAR SOUTH AS AROUND KFSD...BUT EXPECT STRONGER COVERAGE OF LOW REFLECTIVITIES ON KABR RADAR TO DWINDLE SOMEWHAT WITH INCREASING DISTANCE FROM WEAK TERRAIN SUPPORT. EARLIER FLURRIES IN SW MN COULD HAVE IMPACTED SOMEWHAT MORE RAPID DISSIPATION IN CLOUDS...AND MAY ALSO INFLUENCE THE CLEARING TREND. TEMPS ALSO CHALLENGING WITH CONTINUED LOW LEVEL COLD AIR ADVECTION...BUT TEMPS ALREADY REACHING INDICATED MIXING POTENTIAL UNDER CLOUDY AREAS BY MID MORNING. PROBABLY NOT MUCH ROOM TO WARM MORE THAN A FEW DEGREES ANYWHERE TODAY...MOST SO IN AREAS WITH SUNSHINE TO THE EAST. UPDATES OUT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 520 AM CST THU NOV 28 2013 CURRENT SURFACE ANALYSIS SHOWS THE FRONTAL BOUNDARY HAVING PUSHED THROUGH OUR CWA EARLY THIS MORNING...WITH AN AREA OF STRATUS STREAMING INTO OUR WESTERN CWA BEHIND THE EXITING SYSTEM. THE SURFACE RIDGE AXIS PRESENTLY LOCATED THROUGH THE WESTERN PORTIONS OF THE DAKOTA WILL SLIDE TO THE SOUTH AND EAST TODAY...AND WITH DRYING AND SUBSIDENCE LOOKING FOR THE LOW CLOUDS TO THIN OUT ACROSS THE AREA BY LATE MORNING OR EARLY AFTERNOON. OTHERWISE...IT WILL BE BREEZY DURING THE EARLY PART OF THE DAY...ESPECIALLY IN THE EAST...WITH COLD AIR ADVECTION AND A DECENT GRADIENT ACROSS THE AREA...THEN TAPERING DOWN IN THE AFTERNOON AS HIGH PRESSURE BUILDS IN AND THE GRADIENT RELAXES AND ML WINDS DECREASE. THERMAL PROFILES DO COOL A BIT TODAY...THOUGH NOTHING TOO EXTREME WITH HIGHS STILL MAKING IT INTO THE MID 20S TO LOWER 30S FROM NORTHEAST TO SOUTHWEST RESPECTIVELY. THE HIGH PRESSURE MOVES QUICKLY TO THE EAST TONIGHT...AND WITH THAT WINDS WILL TRANSITION TO SOUTHEASTERLY AND PICK UP LATER AT NIGHT. IT WILL STILL BE A COLD NIGHT WITH LOWS IN THE UPPER SINGLE DIGITS TO TEENS...WITH TEMPS STEADYING OUT OR RISING SOME LATE AT NIGHT AS THE WINDS INCREASE. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 520 AM CST THU NOV 28 2013 POTENT PACIFIC LOW DIVES INTO THE PACIFIC NORTHWEST FRIDAY AND SATURDAY...SHIFTING THE INTERMOUNTAIN WEST RIDGING ITO THE PLAINS STATES. A STRONG PUSH OF WARM AIR ADVECTION AND BREEZY SOUTHERLY WINDS WILL BRING MILDER TEMPERATURES ON FRIDAY DESPITE SOME PASSING MID AND HIGH CLOUDS FILTERING THE SUNSHINE. HIGHS WILL WARM TO SLIGHTLY ABOVE NORMAL READINGS IN THE LOW 30S EAST TO THE MID 40S WEST. A WEAK FRONT SAGS ACROSS THE FORECAST AREA FRIDAY NIGHT THROUGH SATURDAY MORNING...BUT WITHOUT MOISTURE OR A REAL COLD AIR PUSH BEHIND IT...CONDITIONS WILL REMAIN DRY AND MILD WITH HIGHS MIXING INTO THE UPPER 30S TO MID 40S. MUCH GREATER UNCERTAINTY SHOWS UP EARLY NEXT WEEK AS THE PACIFIC TROUGH STRENGTHENS AND MOVES INTO THE NORTHERN ROCKIES. MODELS STILL SHOWING SIGNIFICANT DIFFERENCES IN THE STRENGTH...TIMING AND TRACK OF THE UPPER LOW. THE GFS FOLLOWS A MORE NORTHERLY TRACK WHILE THE ECMWF IS SLOWER AND FURTHER SOUTH. FINALLY...THE CANADIAN DEPICTS A MUCH WEAKER SYSTEM OVERALL WHICH GIVEN THE ENERGETIC NATURE OF THIS SYSTEM SEEMS THE LEAST LIKELY. INITIAL SHORTWAVE AHEAD OF THE MAIN SYSTEM SLIDES SOUTHEAST ACROSS THE REGION AROUND THE SUNDAY NIGHT/MONDAY TIME FRAME. WITH THE GFS RAPIDLY AMPLIFYING THE PAC NW TROUGH AND UPPER RIDGE AHEAD OF IT...THIS WAVE IS WEAKER AND FASTER MOVING THAN THE ECMWF WHICH DEVELOPS AN INVERTED TROUGH FEATURE OVER THE NORTHERN AND CENTRAL PLAINS AND KEEPS IT IN THE PICTURE WELL INTO TUESDAY. SIGNIFICANT DIFFERENCES IN TEMPERATURE PROFILES ALSO MAKE PRECIPITATION TYPES DIFFICULT TO PINPOINT. TEMPERATURES LOOK TO REMAIN SEASONALLY MILD THROUGH WEDNESDAY WITH MUCH COOLER READINGS ARRIVING LATE IN THE WEEK. FOR NOW WILL KEEP MENTION OF BOTH RAIN AND SNOW. NOT MUCH CONFIDENCE IN THE TIMING OF THE PRECIPITATION BUT CHANCES DO APPEAR TO IMPROVE AS WE MOVE TOWARDS MID WEEK AS THE MAIN PACIFIC TROUGH ADVANCES TOWARDS THE REGION. FOR NOW DID NOT ALTER THE ALLBLEND POPS OR TEMPS MUCH GIVEN SUCH UNCERTAINTY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 520 AM CST THU NOV 28 2013 STRATUS CONTINUES TO EXPAND SOUTHWARD BEHIND EXITING COLD FRONT...AND THE CHALLENGE BECOMES WHEN THIS AREA OF LOW CLOUDS WILL BREAK UP. WITH HIGH PRESSURE BUILDING ACROSS THE REGION AND ASSOCIATED SUBSIDENCE AND DRYING...WOULD EXPECT CLOUDS TO BEGIN TO DISSIPATE BY MID AFTERNOON. THERE IS SOME DISAGREEMENT AMONG MODELS...WITH THE RAP HOLDING IT IN THROUGH AT LEAST LATE AFTERNOON. AT THIS POINT WILL LEAN A LITTLE EARLIER WITH CLOUDS SCATTERING OUT MOST PLACES AFTER AROUND 19Z. OTHERWISE...NORTHWESTERLY WINDS...GUSTY AT TIMES EARLY...WILL TAPER DOWN...BECOMING LIGHT BY THIS EVENING. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ UPDATE...CHAPMAN SHORT TERM... LONG TERM...JM AVIATION...JM
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
528 AM CST THU NOV 28 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 520 AM CST THU NOV 28 2013 CURRENT SURFACE ANALYSIS SHOWS THE FRONTAL BOUNDARY HAVING PUSHED THROUGH OUR CWA EARLY THIS MORNING...WITH AN AREA OF STRATUS STREAMING INTO OUR WESTERN CWA BEHIND THE EXITING SYSTEM. THE SURFACE RIDGE AXIS PRESENTLY LOCATED THROUGH THE WESTERN PORTIONS OF THE DAKOTA WILL SLIDE TO THE SOUTH AND EAST TODAY...AND WITH DRYING AND SUBSIDENCE LOOKING FOR THE LOW CLOUDS TO THIN OUT ACROSS THE AREA BY LATE MORNING OR EARLY AFTERNOON. OTHERWISE...IT WILL BE BREEZY DURING THE EARLY PART OF THE DAY...ESPECIALLY IN THE EAST...WITH COLD AIR ADVECTION AND A DECENT GRADIENT ACROSS THE AREA...THEN TAPERING DOWN IN THE AFTERNOON AS HIGH PRESSURE BUILDS IN AND THE GRADIENT RELAXES AND ML WINDS DECREASE. THERMAL PROFILES DO COOL A BIT TODAY...THOUGH NOTHING TOO EXTREME WITH HIGHS STILL MAKING IT INTO THE MID 20S TO LOWER 30S FROM NORTHEAST TO SOUTHWEST RESPECTIVELY. THE HIGH PRESSURE MOVES QUICKLY TO THE EAST TONIGHT...AND WITH THAT WINDS WILL TRANSITION TO SOUTHEASTERLY AND PICK UP LATER AT NIGHT. IT WILL STILL BE A COLD NIGHT WITH LOWS IN THE UPPER SINGLE DIGITS TO TEENS...WITH TEMPS STEADYING OUT OR RISING SOME LATE AT NIGHT AS THE WINDS INCREASE. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 520 AM CST THU NOV 28 2013 POTENT PACIFIC LOW DIVES INTO THE PACIFIC NORTHWEST FRIDAY AND SATURDAY...SHIFTING THE INTERMOUNTAIN WEST RIDGING ITO THE PLAINS STATES. A STRONG PUSH OF WARM AIR ADVECTION AND BREEZY SOUTHERLY WINDS WILL BRING MILDER TEMPERATURES ON FRIDAY DESPITE SOME PASSING MID AND HIGH CLOUDS FILTERING THE SUNSHINE. HIGHS WILL WARM TO SLIGHTLY ABOVE NORMAL READINGS IN THE LOW 30S EAST TO THE MID 40S WEST. A WEAK FRONT SAGS ACROSS THE FORECAST AREA FRIDAY NIGHT THROUGH SATURDAY MORNING...BUT WITHOUT MOISTURE OR A REAL COLD AIR PUSH BEHIND IT...CONDITIONS WILL REMAIN DRY AND MILD WITH HIGHS MIXING INTO THE UPPER 30S TO MID 40S. MUCH GREATER UNCERTAINTY SHOWS UP EARLY NEXT WEEK AS THE PACIFIC TROUGH STRENGTHENS AND MOVES INTO THE NORTHERN ROCKIES. MODELS STILL SHOWING SIGNIFICANT DIFFERENCES IN THE STRENGTH...TIMING AND TRACK OF THE UPPER LOW. THE GFS FOLLOWS A MORE NORTHERLY TRACK WHILE THE ECMWF IS SLOWER AND FURTHER SOUTH. FINALLY...THE CANADIAN DEPICTS A MUCH WEAKER SYSTEM OVERALL WHICH GIVEN THE ENERGETIC NATURE OF THIS SYSTEM SEEMS THE LEAST LIKELY. INITIAL SHORTWAVE AHEAD OF THE MAIN SYSTEM SLIDES SOUTHEAST ACROSS THE REGION AROUND THE SUNDAY NIGHT/MONDAY TIME FRAME. WITH THE GFS RAPIDLY AMPLIFYING THE PAC NW TROUGH AND UPPER RIDGE AHEAD OF IT...THIS WAVE IS WEAKER AND FASTER MOVING THAN THE ECMWF WHICH DEVELOPS AN INVERTED TROUGH FEATURE OVER THE NORTHERN AND CENTRAL PLAINS AND KEEPS IT IN THE PICTURE WELL INTO TUESDAY. SIGNIFICANT DIFFERENCES IN TEMPERATURE PROFILES ALSO MAKE PRECIPITATION TYPES DIFFICULT TO PINPOINT. TEMPERATURES LOOK TO REMAIN SEASONALLY MILD THROUGH WEDNESDAY WITH MUCH COOLER READINGS ARRIVING LATE IN THE WEEK. FOR NOW WILL KEEP MENTION OF BOTH RAIN AND SNOW. NOT MUCH CONFIDENCE IN THE TIMING OF THE PRECIPITATION BUT CHANCES DO APPEAR TO IMPROVE AS WE MOVE TOWARDS MID WEEK AS THE MAIN PACIFIC TROUGH ADVANCES TOWARDS THE REGION. FOR NOW DID NOT ALTER THE ALLBLEND POPS OR TEMPS MUCH GIVEN SUCH UNCERTAINTY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 520 AM CST THU NOV 28 2013 STRATUS CONTINUES TO EXPAND SOUTHWARD BEHIND EXITING COLD FRONT...AND THE CHALLENGE BECOMES WHEN THIS AREA OF LOW CLOUDS WILL BREAK UP. WITH HIGH PRESSURE BUILDING ACROSS THE REGION AND ASSOCIATED SUBSIDENCE AND DRYING...WOULD EXPECT CLOUDS TO BEGIN TO DISSIPATE BY MID AFTERNOON. THERE IS SOME DISAGREEMENT AMONG MODELS...WITH THE RAP HOLDING IT IN THROUGH AT LEAST LATE AFTERNOON. AT THIS POINT WILL LEAN A LITTLE EARLIER WITH CLOUDS SCATTERING OUT MOST PLACES AFTER AROUND 19Z. OTHERWISE...NORTHWESTERLY WINDS...GUSTY AT TIMES EARLY...WILL TAPER DOWN...BECOMING LIGHT BY THIS EVENING. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM... LONG TERM...JM AVIATION...JM
SEE BELOW FOR AN UPDATED AVIATION FORECAST DISCUSSION.

&& .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH SATURDAY AN EXTENSIVE STRATUS DECK OVER THE REGION IS KEEPING TEMPERATURES RELATIVELY MILD WITH CURRENT READINGS IN THE MID 20S. BASED ON THE PAST FEW RUNS OF THE RUC...IT SEEMS UNLIKELY THIS STRATUS DECK WILL DISSIPATE ANYTIME SOON. WOULD NOT BE TOO SURPRISED IF THESE CLOUDS HANG AROUND THROUGH THIS AFTERNOON BEFORE DRIER AIR AT 925 MB MOVES IN FROM THE SOUTHWEST. OF COURSE THESE CLOUDS WILL MAKE FORECASTING HIGH TEMPERATURES RATHER DIFFICULT. HAVE RELIED UPON THE RUC MODEL WHICH SHOWS A SLIGHT COOL DOWN AROUND SUNRISE...THEN A SLIGHT INCREASE BY 21Z. HIGH PRESSURE SHIFTS EAST OF THE REGION TONIGHT...ALLOWING WAA TO SPREAD ACROSS THE WESTERN CWA WHERE TEMPERATURES SHOULD BECOME STEADY OR SLOWLY RISE AFTER MIDNIGHT. ANOTHER WEAK LOW PRESSURE SYSTEM PASSING ACROSS THE REGION ON FRIDAY WILL BRING WARM TEMPERATURES BACK INTO THE AREA. TEMPS AT 925/850 MB ARE PROJECTED TO RANGE AROUND NORMAL...WHICH WHEN COMBINED WITH DECENT MIXING WINDS SHOULD EQUAL HIGHS IN THE MID 30S...TO THE MID 40S. WOULD NOT BE TOO SURPRISED IF HIGH TEMPERATURES END UP BEING WARMER. SLIGHTLY COOLER LOW LEVEL TEMPERATURES ALONG WITH WEAK CAA ON SATURDAY WILL RESULT IN HIGHS IN THE LOW TO MID 30S. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY LATEST MODEL RUNS CONTINUE TO FORECAST A MAJOR PATTERN SHIFT DURING THE LONG TERM. HOWEVER THE DETAILS REMAIN SKETCHY AS EACH MODEL HAS ITS OWN IDEA ON HOW TO HANDLE ENERGY WITHIN THE DEVELOPING MID LEVEL TROF AND THAT TROFS EVOLUTION THROUGH THE MIDDLE OF NEXT WEEK. THE ECMWF IS BY FAR THE MOST AGGRESSIVE IN SETTING UP A BAROCLINIC ZONE ACROSS THE REGION AND CRANKS OUT COPIOUS AMOUNTS OF PCPN FROM TUESDAY THROUGH THURSDAY. THE GFS IS MORE PROGRESSIVE AND FEATURES A MORE POSITIVE TILT MID LEVEL TROF OVER THE WESTERN/CENTRAL CONUS LEADING TO A LESS INTENSE BAROCLINIC ZONE OVER THE NORTHERN PLAINS. THE LAST COUPLE RUNS OF THE ECMWF HAVE BEEN CONSISTENTLY SLOWER AND WETTER VS THE GFS. BUT IT SEEMS OVERLY WET. NONETHELESS WILL BE AN INTERESTING MIDDLE OF NEXT WEEK WEATHER-WISE WITH A MIXED BAG OF PCPN EXPECTED NO MATTER WHICH MODEL YOU LIKE. TEMPERATURES ARE EXPECTED TO BE ABOVE NORMAL FOR THE FIRST PART OF THE PERIOD...BUT THEN TRANSITION TOWARD NORMAL AS COLDER AIR INVADES FROM CANADA TOWARD MID TO LATE WEEK. && .AVIATION... 12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS MVFR CIGS ARE EXPECTED TO PERSIST AT LEAST INTO THE AFTERNOON FOR MOST TERMINALS. MOST AREAS SHOULD BECOME VFR BY EVENING. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...TDK SHORT TERM...SD LONG TERM...TDK AVIATION...TDK WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
331 AM CST THU NOV 28 2013 .SHORT TERM...TODAY THROUGH SATURDAY AN EXTENSIVE STRATUS DECK OVER THE REGION IS KEEPING TEMPERATURES RELATIVELY MILD WITH CURRENT READINGS IN THE MID 20S. BASED ON THE PAST FEW RUNS OF THE RUC...IT SEEMS UNLIKELY THIS STRATUS DECK WILL DISSIPATE ANYTIME SOON. WOULD NOT BE TOO SURPRISED IF THESE CLOUDS HANG AROUND THROUGH THIS AFTERNOON BEFORE DRIER AIR AT 925 MB MOVES IN FROM THE SOUTHWEST. OF COURSE THESE CLOUDS WILL MAKE FORECASTING HIGH TEMPERATURES RATHER DIFFICULT. HAVE RELIED UPON THE RUC MODEL WHICH SHOWS A SLIGHT COOL DOWN AROUND SUNRISE...THEN A SLIGHT INCREASE BY 21Z. HIGH PRESSURE SHIFTS EAST OF THE REGION TONIGHT...ALLOWING WAA TO SPREAD ACROSS THE WESTERN CWA WHERE TEMPERATURES SHOULD BECOME STEADY OR SLOWLY RISE AFTER MIDNIGHT. ANOTHER WEAK LOW PRESSURE SYSTEM PASSING ACROSS THE REGION ON FRIDAY WILL BRING WARM TEMPERATURES BACK INTO THE AREA. TEMPS AT 925/850 MB ARE PROJECTED TO RANGE AROUND NORMAL...WHICH WHEN COMBINED WITH DECENT MIXING WINDS SHOULD EQUAL HIGHS IN THE MID 30S...TO THE MID 40S. WOULD NOT BE TOO SURPRISED IF HIGH TEMPERATURES END UP BEING WARMER. SLIGHTLY COOLER LOW LEVEL TEMPERATURES ALONG WITH WEAK CAA ON SATURDAY WILL RESULT IN HIGHS IN THE LOW TO MID 30S. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY LATEST MODEL RUNS CONTINUE TO FORECAST A MAJOR PATTERN SHIFT DURING THE LONG TERM. HOWEVER THE DETAILS REMAIN SKETCHY AS EACH MODEL HAS ITS OWN IDEA ON HOW TO HANDLE ENERGY WITHIN THE DEVELOPING MID LEVEL TROF AND THAT TROFS EVOLUTION THROUGH THE MIDDLE OF NEXT WEEK. THE ECMWF IS BY FAR THE MOST AGGRESSIVE IN SETTING UP A BAROCLINIC ZONE ACROSS THE REGION AND CRANKS OUT COPIOUS AMOUNTS OF PCPN FROM TUESDAY THROUGH THURSDAY. THE GFS IS MORE PROGRESSIVE AND FEATURES A MORE POSITIVE TILT MID LEVEL TROF OVER THE WESTERN/CENTRAL CONUS LEADING TO A LESS INTENSE BAROCLINIC ZONE OVER THE NORTHERN PLAINS. THE LAST COUPLE RUNS OF THE ECMWF HAVE BEEN CONSISTENTLY SLOWER AND WETTER VS THE GFS. BUT IT SEEMS OVERLY WET. NONETHELESS WILL BE AN INTERESTING MIDDLE OF NEXT WEEK WEATHER-WISE WITH A MIXED BAG OF PCPN EXPECTED NO MATTER WHICH MODEL YOU LIKE. TEMPERATURES ARE EXPECTED TO BE ABOVE NORMAL FOR THE FIRST PART OF THE PERIOD...BUT THEN TRANSITION TOWARD NORMAL AS COLDER AIR INVADES FROM CANADA TOWARD MID TO LATE WEEK. && .AVIATION... 06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS MVFR STRATUS /1500FT TO 2500FT AGL CIGS/ IS SPREADING OVER ALL FOUR TERMINALS. KATY SHOULD SEE THE STRATUS WORKING IN BY 08Z. CURRENT MODEL DEPICTIONS SUGGEST THE CLOUDS ARE BREAKING UP OR LIFTING BY AROUND 18Z THURSDAY. THERE COULD ALSO END UP BEING A FEW SNOW FLURRIES OBSERVED FALLING OUT OF THIS STRATUS FIELD BEFORE IT`S ALL SAID AND DONE. WINDS WILL BE FROM THE NORTHWEST AT ALL FOUR TERMINALS THROUGH THURSDAY MORNING BEFORE SURFACE HIGH PRESSURE BUILDING INTO THE REGION TURNS THEM LIGHT AND VARIABLE AND THEN EVENTUALLY SOUTHEASTERLY AROUND 5 TO 10 KNOTS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...SD LONG TERM...TDK AVIATION...DORN WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
925 PM EST FRI NOV 29 2013 .SYNOPSIS... HIGH PRESSURE WILL BE ACROSS THE REGION THROUGH THE WEEKEND WHILE A SERIES OF UPPER LEVEL DISTURBANCES PASS NORTH OF THE REGION. A WEAK DISTURBANCE WILL PASS THROUGH THE AREA ON MONDAY WHILE AN AREA OF LOW PRESSURE MOVES NORTH ALONG THE COAST. THE NEXT SYSTEM TO BRING PRECIPITATION TO MOST OF OUR REGION WILL ARRIVE THURSDAY INTO FRIDAY. && .NEAR TERM /THROUGH SATURDAY/... AS OF 920 PM EST FRIDAY ADJUSTED OVERNIGHT MIN TEMPS DOWN A FEW DEGREES AS SKIES REMAIN CLEAR SO FAR WITH CALMS WINDS NEARLY EVERYWHERE. STILL HOLDING TO IDEA OF LOW CLOUDS DRIFTING SW ACROSS THE MOUNTAINS BY THE EARLY MORNING HOURS AS SHOWN BY LATEST RAP AND NAM MODELS WHICH WOULD ARREST THE DOWNWARD TRAJECTORY IN TEMPS SOMEWHAT. LOWERED WINDS SLIGHTLY AS WELL BUT OTHERWISE NO SUBSTANTIVE CHANGES. PREVIOUS VALID DISCUSSION AS OF 300 PM EST FRIDAY... A WEAK UPPER LEVEL DISTURBANCE WILL PROGRESS THROUGH THE GREAT LAKES REGION TONIGHT INTO SATURDAY. SURFACE HIGH PRESSURE WILL BECOME CENTERED OVER NEW ENGLAND BY SATURDAY MORNING...AND ITS ASSOCIATED RIDGE AXIS WILL TRAIL SOUTHWEST ALONG THE LEE OFF THE APPALACHIANS. LOW LEVEL MOISTURE HAS BEEN ABUNDANT TODAY FROM NORTHERN WEST VIRGINIA...NORTH INTO PENNSYLVANIA. TWO WEATHER PATTERNS WILL CONTRIBUTE TO INCREASING CLOUD COVER TONIGHT INTO SATURDAY. FIRST...THE ADVANCING SYSTEM THROUGH THE GREAT LAKES REGION HAS ALREADY ALLOWED FOR SOME DOWNSTREAM ADVANCEMENT OF MID TO HIGH LEVEL CLOUD COVER OVER PARTS OF INDIANA AND KENTUCKY. THIS CLOUD COVER WILL PROGRESS INTO OUR REGION OVERNIGHT WITH INCREASING COVERAGE THROUGH SATURDAY. THE GREATEST CONCENTRATION WILL OVER THE NORTHERN PARTS OF THE FORECAST AREA. SECOND...BOTH 12Z/7AM GFS AND TO A GREATER DEGREE THE 12Z/7AM NAM ARE DEPICTING A SOUTHERN ADVANCEMENT OF THE WV/MD/PA MOISTURE ALONG THE LEE OF THE APPALACHIANS OVERNIGHT. THIS MOISTURE IS DEPICTED AS BEING SHALLOW WITHIN ROUGHLY THE 925-900 MB LAYER. 925 MB WINDS WILL BE COMPARABLE TO THE ORIENTATION TYPICALLY ASSOCIATED WITH ONSET OF A HIGH PRESSURE RIDGE ALONG COMMON DAMMING AREA. 925 MB WINDS WILL GRADUALLY VEER OVERNIGHT TO NORTHEAST AND THEN TO THE EAST. THE WV/MD/PA MOISTURE IS PROGGED TO GET CAUGHT UP IN THIS FLOW AND EVENTUALLY TAKE AN UPSLOPE ORIENTATION TO THE BLUE RIDGE. THIS WILL HELP IN THE FORMATION OF LOW LEVEL CLOUD COVER ACROSS THOSE REGIONS OF THE FORECAST AREA GENERALLY ALONG AND WEST OF THE CREST OF THE BLUE RIDGE. THE WINDOW OF BEST COVERAGE WILL BE FROM ROUGHLY 300 AM SATURDAY THROUGH 10AM SATURDAY. PAST THIS POINT THE NOCTURNAL INVERSION WILL HAVE ERODED AND THE CLOUDS BEGIN TO DISSIPATE. FOR LOWS TONIGHT...I HAVE FAVORED NUMBERS AT OR SLIGHTLY ABOVE GUIDANCE IN THOSE AREAS THAT WILL EXPERIENCE THE BULK OF THE AFOREMENTIONED CLOUD COVER. FOR SATURDAY...THE REGION WILL STILL BE CONTENDING WITH THE MID TO HIGH LEVEL CLOUD COVER...AGAIN PRIMARILY IN THE NORTH...IN ASSOCIATION WITH PASSING SHORTWAVE TROUGH TO OUR NORTH. CLOSER TO THE SURFACE...THE 925 MB FLOW BECOMES EASTERLY THE WHOLE WAY TO THE COAST. THIS WILL ALLOW ATLANTIC MOISTURE TO PROGRESS INTO AT LEAST THE PIEDMONT REGION OF THE FORECAST AREA BY THE LATE AFTERNOON. WILL BE SHOWING INCREASING CLOUD COVER IN THIS REGION TO ACCOUNT FOR THIS. HAVE NOT DEVIATED TOO FAR FROM A BLEND OF THE GFS AND NAM MOS FOR HIGH TEMPERATURES. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 240 PM EST FRIDAY... ZONAL FLOW ALOFT OVER THE MID APPALACHIAN AND MID ATLANTIC REGION WILL GRADUALLY BE REPLACED BY MEAN TROFING OVER THE EASTERN PORTION OF THE NATION BY THE END OF THE SHORT TERM PERIOD AS A SERIES OF WEAK SHORT WAVE TROFS EMBEDDED IN NORTHERN STREAM HELPS TO SLOWLY BUCKLE UPPER FLOW. PRESENCE OF WEAK SURFACE HIGH PRESSURE...NEGLIGIBLE THERMAL ADVECTION...AND PRESENCE OF HIGH AND OCCASIONALLY MID LEVEL CLOUDS UNDER REGION OF CHANNELIZED VORTICITY SHOULD MAINTAIN RATHER UNEVENTFUL WEATHER OVER THE BLACKSBURG FORECAST AREA SATURDAY NIGHT THROUGH SUNDAY NIGHT WITH SOMEWHAT MODERATED DIURNAL TEMPERATURE PROFILE. NIGHTTIME LOWS EXPECTED TO RANGE FROM THE MID 20S TO LOWER 30S IN MOST AREAS...WITH COOLEST READINGS IN THE DEEPER VALLEYS... AND MILDER READINGS ACROSS THE RIDGELINES AND NC FOOTHILLS. DAYTIME HIGHS ON SATURDAY EXPECTED TO RANGE FROM THE LOWER TO MID 40S IN THE MOUNTAINS TO LOWER 50S ACROSS THE PIEDMONT. A MORE SIGNIFICANT SHORT WAVE IS EXPECTED TO AMPLIFY UPPER FLOW AS IT DIVES EAST-SOUTHEAST OUT OF THE MISSISSIPPI VALLEY ON MONDAY...REACHING THE EAST COAST BY LATE MONDAY NIGHT. BACKING FLOW ALOFT WILL HELP STRENGTHEN BAROCLINIC ZONE ALONG THE SOUTHEAST COAST...RESULTING IN CYCLOGENESIS WITH SURFACE LOW EXPECTED TO DEVELOP AND STRENGTHEN ALONG THE COAST BY LATE IN SHORT TERM PERIOD. MID-RANGE MODELS NOT YET CONSISTENTLY RESOLVING DEVELOPMENT... PLACEMENT...AND TIMING OF THIS FEATURE...YET MOST IMPLY THAT FLOW WILL NOT AMPLIFY SUFFICIENTLY OR SOON ENOUGH TO ALLOW DEVELOPING AREA OF PRECIPITATION IN ISENTROPIC ZONE TO SIGNIFICANTLY THREATEN BLACKSBURG AREA OF CONCERN BEFORE MOVING OFF THE EAST. CONSIDERING THAT PAST COUPLE OF MODEL TRENDS HAVE BECOME A BIT MORE BULLISH IN AMPLIFICATION OF THIS SYSTEM...WILL CONTINUE TO MAINTAIN A LOW THREAT FOR PRECIPITATION IN MOST AREAS MONDAY AFTERNOON INTO MONDAY NIGHT...WITH HIGHEST THREAT FOR PRECIPITATION EXPECTED TO BE RESTRICTED TO MAINLY NORTHWESTERN MOUNTAINS WHERE LOCAL UPSLOPING WILL BE MAXIMIZED. CONSIDERING THERMAL PROFILE...ANY PRECIPITATION ON MONDAY WILL LIKELY COME IN THE FORM OF SPOTTY LIGHT SHOWERS...HOWEVER INCREASING COLD ADVECTION ON BACKSIDE OF COASTAL LOW WILL LIKELY BE/BECOME SUFFICIENT ENOUGH TO ALLOW CHANGEOVER TO SNOW OR RAIN/SNOW MIX IN MOUNTAINS ON MONDAY NIGHT. FURTHER EAST...EVEN IF COASTAL LOW IS ABLE TO CRANK UP FAST ENOUGH TO PUSH PRECIPITATION UNDER DEVELOPING DEFORMATION ZONE WESTWARD INTO EASTERN PIEDMONT COUNTIES...THERMAL PROFILE IN THAT AREA LIKELY TO REMAIN ABOVE FREEZING (HENCE ONLY A COLD RAIN) UNTIL SYSTEM LIFTS AWAY FROM THE AREA BY/BEFORE DAYBREAK TUESDAY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 300 PM EST FRIDAY... THE BEGINNING OF THE LONG TERM PERIOD WILL BEGIN WITH SOME UPSLOPE PRECIPITATION ACROSS THE MOUNTAINS. BOTH THE GFS AND THE ECMWF SHOW PRECIPITATION THROUGH ABOUT 6Z WEDNESDAY. LIKELY WILL BE SNOW SHOWERS ACROSS WESTERN GREENBRIER WITH A MIX OF RAIN AND SNOW ACROSS LOWER ELEVATION MOUNTAIN AREAS. MODELS ALSO AGREE THAT THERE WILL CONTINUE TO BE A GENERAL WARMING TREND AS 500 MB HEIGHT LEVELS CONTINUE TO RISE THROUGH THE WEEK. FROM THURSDAY ON THROUGH SATURDAY 850MB TEMPS WILL BE +5-10C. THIS SHOULD ALLOW DAYTIME MAX TEMPS TO EASILY REACH THE 50S AND EVEN LOWER 60S EAST OF THE BLUE RIDGE BY THE END OF THE WEEK. WHILE WE WILL BE WARMER...A STRONG COLD FRONT WILL BEGIN TO APPROACH THE REGION ON THURSDAY AND FRIDAY. BOTH THE GFS AND ECMWF BRING MOISTURE IN AHEAD OF THE FRONT. CHANCE SHOWERS ARE MENTIONED FROM THURSDAY THROUGH THE REST OF THE LONG TERM PERIOD ON 12Z SATURDAY. LOOKING BEYOND SATURDAY...A DEEP TROUGH ACROSS THE WESTERN UNITED STATES WILL BRING PLENTY OF COLD AIR FROM CANADA ALL THE WAY INTO THE CENTRAL PLAINS. BY THE END OF THE 240HR MODEL RUN OUR REGION CONTINUES TO BE UNDER THE INFLUENCE OF THE RIDGE AND THUS WILL STAY ON THE WARMER SIDE. A CLOSER EYE WILL BE PAID TO FUTURE MODEL RUNS TO SEE HOW THE PATTERN PROGRESSES. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... AS OF 630 PM EST FRIDAY... VFR CONDITIONS PREVAIL ACROSS THE REGION THIS EVENING AS HIGH PRESSURE BUILDS INTO THE REGION BUT SHORT-WAVR PASSING TO OUR NORTH HAS BROUGHT SOME LOW LEVEL MOISTURE AS CLOSE TO THE REGION AS NORTHERN WV AND SOUTHERN PA. OVERNIGHT...MODELS CONTINUE TO SHOW SOME OF THIS LOW LEVEL MOISTURE OVER WV/MD/PA WORKING SOUTH AND THEN WEST AS LOW LEVEL WINDS VEER MORE TO THE NORTHEAST OVER THE PIEDMONT AND EAST OVER THE MOUNTAINS. RAP/NAM/GFS MODELS ALL CONTINUE TO SHOW THIS SHALLOW RIBBON OF MOISTURE AROUND THE 925-900 MB LEVEL ADVECTING INTO THE REGION BETWEEN ROUGHLY 03Z-06Z /10PM- 1AM TONIGHT AND PROVIDE FOR SCT-BKN MVFR LEVEL CLOUDS. THE CONCENTRATION IS EXPECTED TO BE GREATEST ALONG AND WEST OF A KTNB- KBCB-KLWB LINE. THIS MOISTURE WILL REMAIN TRAPPED UNDER THE NOCTURNAL INVERSION UNTIL IT HAS A CHANCE TO ERODE AROUND 14Z-15Z /9AM-10AM SATURDAY. ADDITIONAL MVFR CLOUDS ARE POSSIBLE SATURDAY AFTERNOON AND EVENING AS LOW LEVEL WINDS ACROSS THE PIEDMONT VEER MORE EASTERLY AND WE START TO TAP ATLANTIC MOISTURE INTO THE REGION. BY LATE SATURDAY NIGHT LOW LEVEL WINDS ARE EXPECTED TO HAVE VEERED SOUTHWEST...AND WE LOSE THE UPLSOPE COMPONENT RESPONSIBLE FOR THE MVFR CLOUDS. SUNDAY INTO MONDAY MAINLY VFR CONDITIONS ARE EXPECTED AS WE BECOME POSITIONED BETWEEN A LOW MOVING NORTH ALONG THE COAST AND A TROUGH AXIS OVER THE OH/TN VALLEY. ISOLATED TO SCATTERED RAIN/SNOW SHOWERS WILL BE POSSIBLE BY MONDAY NIGHT AS THE TROUGH APPROACHES FROM THE WEST. TUESDAY INTO WEDNESDAY MAINLY VFR CONDITIONS ARE EXPECTED AS THE TROUGH PASSES TO OUR EAST AND AN AREA OF LOW PRESSURE DEVELOPS OFF THE COAST. OUR REGION WILL BE LEFT IN A NORTHWEST FLOW PATTERN WITH THE POTENTIAL FOR UPSLOPE CLOUDS OVER THE MOUNTAINS. THERE MAY BE PATCHY MVFR CIGS WITHIN THESE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...DS NEAR TERM...DS/PC SHORT TERM...WERT LONG TERM...CF AVIATION...DS/PC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
325 PM CST THU NOV 28 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 325 PM CST THU NOV 28 2013 AT 3 PM...A LAKE INDUCED VORTICITY WAS LOCATED OVER THE APOSTLE ISLANDS IN WESTERN LAKE SUPERIOR. MEANWHILE A SURFACE LOW WAS LOCATED OVER EASTERN UPPER MICHIGAN. THIS LOW WAS PRODUCING WEAK CYCLONIC FLOW ACROSS ACROSS WISCONSIN AND EAST CENTRAL MINNESOTA. THIS CYCLONIC FLOW ALONG WITH STEEP 950-900 MB LAPSE RATES /ASSOCIATED WITH A THERMAL TROUGH LOCATED FROM NORTHERN MINNESOTA SOUTHEAST INTO EASTERN WISCONSIN/ IS HELPING MAINTAIN THESE CLOUDS. THE 28.19Z RAP HAS A VERY GOOD HANDLE ON THESE CLOUDS AND THEY SHOW THAT THEY WILL CONTINUE TO MOVE SOUTHEAST ACROSS MAINLY OUR WISCONSIN COUNTIES AND THEN QUICKLY DISSIPATES THEM BETWEEN 28.01Z AND 28.03Z AS THE FLOW STARTS TO BECOME ANTICYCLONIC AND THE 950-900 MB LAPSE RATES DECREASE. FROM LATE TONIGHT INTO FRIDAY...THE 28.12Z MODELS CONTINUE TO SHOW THAT WEAK WARM AIR ADVECTION WILL DEVELOP ABOVE 600 MB AS A WEAK SHORT WAVE TROUGH APPROACHES THE REGION FROM THE CENTRAL PLAINS. THIS WILL RESULT IN SOME MID TO HIGH CLOUDS ACROSS THE AREA. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 325 PM CST THU NOV 28 2013 ON FRIDAY NIGHT...THE 28.12Z MODELS CONTINUE TO SHOW THAT A STRONG SHORT WAVE TROUGH WILL MOVE SOUTHEAST ACROSS SOUTHWEST ONTARIO. MUCH OF THE PV ADVECTION ASSOCIATED WITH THIS SYSTEM STAYS WILL NORTH OF THE FORECAST AREA. THERE IS WEAK TO MODERATE 285 TO 300K ISENTROPIC LIFT ACROSS NORTHERN AND EASTERN WISCONSIN. THIS LOWERS THE CONDENSATION PRESSURE DEFICITS TO LESS 40 MB. MEANWHILE AT THE 285 AND 290K ISENTROPIC SURFACES YOU STILL NEED 100 TO 200 MB OF LIFT FOR SATURATION. AS A RESULT...IT IS NOT LOOKING PROMISING FOR ANY PRECIPITATION ACROSS TAYLOR AND NORTHERN CLARK COUNTY IN NORTH CENTRAL WISCONSIN. HOWEVER WITH THE ECMWF...GEM...AND NAM STILL INDICATING A POSSIBILITY. JUST KEPT A SLIGHT CHANCE /LESS THAN 20 PERCENT/ ACROSS THIS AREA. BUFKIT SOUNDINGS CONTINUE TO SHOW NO ICE...SO IF PRECIPITATION DOES INDEED OCCURS IT WOULD BE IN THE FORM OF FREEZING DRIZZLE. ON SATURDAY NIGHT...WEAK TO MODERATE WARM AIR ADVECTION AND STRONG 290 TO 300K ISENTROPIC LIFT DEVELOP ACROSS THE AREA AS A STRONG SHORT WAVE TROUGH MOVES ACROSS THE REGION. THE 290-300K ISENTROPIC CONDENSATION PRESSURE DEFICITS DROP TO LESS THAN 30 MB...SO WE WILL LIKELY SEE CLOUDS WITH THIS WAVE. HOWEVER...THE 285K CONDENSATION DEFICITS REMAIN IN THE 100 TO 200 MB RANGE...SO NOT EXPECTING ANY PRECIPITATION WITH THIS WAVE. FROM SUNDAY NIGHT INTO MONDAY...THE MODELS CONTINUE TO STRUGGLE WITH THE TIMING OF A SHORT WAVE TROUGH COMING OUT AHEAD OF THE DEVELOPING LONG WAVE TROUGH IN THE WESTERN UNITED STATE. BOTH THE GEM AND ECMWF BRING A WAVE AHEAD OF THIS SYSTEM. MEANWHILE THE GFS DOES NOT. AS AS RESULT...THE GEM AND ECMWF PRODUCES SOME LIGHT PRECIPITATION ACROSS THE AREA. MEANWHILE THE GFS KEEPS THE AREA DRY. SINCE THE MODELS HAVE BEEN CONSISTENT...JUST STAYED WITH THE SLIGHT CHANCES THAT THE ALL BLEND PROVIDED. FROM MONDAY NIGHT THROUGH THURSDAY...THE MODELS CONTINUE TO STRUGGLE WITH THE EVOLUTION OF A LONG WAVE TROUGH OVER THE WESTERN UNITED STATES. DUE TO THIS...THERE HAS BEEN A VARIETY OF DIFFERENT LOW PRESSURE TRACKS FROM THE NORTHERN PLAINS EAST INTO THE GREAT LAKES. THIS SYSTEM HAS THE POTENTIAL OF PRODUCING A WINTER STORM SOMEWHERE ACROSS THE REGION...BUT WHERE IS VERY UNCERTAIN...SO JUST STAYED WITH THE ALL BLEND FOR THIS TIME PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1130 AM CST THU NOV 28 2013 SKIES HAVE CLEARED OUT TO START THE TAF FORECAST. A LOW PRESSURE TROUGH WAS SEEN UPSTREAM NEAR MSP...PRODUCING SOME MVFR TO VFR STRATOCUMULUS AND EVEN A FEW FLURRIES. IF THIS TROUGH AND CLOUDS HOLD TOGETHER...THEY WILL ARRIVE IN THE TAF SITES BETWEEN 20-22Z AND HANG AROUND FOR A FEW HOURS. THINKING THE CEILINGS WILL RISE AS THEY RUN INTO DRIER AIR AHEAD OF THEM...THUS HAVE MAINTAINED A SCATTERED VFR CLOUD DECK THROUGH THE AFTERNOON. NEEDLESS TO SAY SOMETHING TO WATCH DURING THE AFTERNOON HOURS. OTHERWISE...ANY OF THIS STRATOCUMULUS SHOULD EITHER EXIT OR DISSIPATE AROUND THE TAF SITES BY 01Z...WITH VFR CONDITIONS PERSISTING THROUGH FRIDAY MORNING. NORTHWEST WINDS OF 10-15KT ARE EXPECTED TO DIMINISH THIS EVENING WITH LOSS OF DAYTIME HEATING AND A RIDGE OF HIGH PRESSURE MOVING IN. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1134 PM CST WED NOV 27 2013 .UPDATE... ISSUED AT 712 PM CST WED NOV 27 2013 FRONTOGENETIC BAND FROM NORTHERN MINNESOTA INTO NORTH CENTRAL WISCONSIN CONTINUES TO PRODUCE EFFICIENT SNOW AMOUNTS WITH DECENT LIFT IN DENDRITIC SNOW GROWTH ZONE. REPORTS OF 2 TO 4 INCHES UPSTREAM...AND EVEN THOUGH FORCING IS FORECAST TO WEAKEN AS SYSTEM ADVECTS EAST...BUMPED UP SNOW ACCUMULATIONS SLIGHTLY MAINLY ALONG AND NORTH OF HIGHWAY 29 IN PARTS OF NORTH CENTRAL WISCONSIN TONIGHT. && .SHORT TERM...(THIS EVENING THROUGH THANKSGIVING) ISSUED AT 310 PM CST WED NOV 27 2013 OVERALL A QUIET WEATHER PERIOD THROUGH THE WEEKEND...AFTER SOME LIGHT SNOW ACROSS THE NORTH TONIGHT. HAVE BEEN MONITORING SHORTWAVE TROUGH 1 MOVING INTO MINNESOTA THIS AFTERNOON WITH LIGHT SNOW IN THE 1-2SM VISIBILITY RANGE...WITH A BIT LOWER FURTHER NORTHWEST ALONG THE MN/CANADA BORDER. ECHO IS INCREASING IN NW WI...BUT THE PRECIPITATION IS WORKING ON SATURATION AND NOT MAKING IT TO THE SURFACE. THE UPPER TROPOSPHERIC SHORTWAVE TROUGH IS LOCATED IN NWRN MN AT 20Z PER GOES WATER VAPOR IMAGERY...WITH SHORTWAVE TROUGH 2 ON ITS HEALS JUST NORTHWEST OF LAKE WINNIPEG. MORNING RAOB AT KMPX WAS DEEPLY DRY BUT THE FORCING WITH THE SHORTWAVE TROUGH IS WORKING PRETTY RAPIDLY TO SATURATE THE COLUMN AND PRODUCE SNOW....ON THE ORDER OF A COUPLE HOURS. PER THE LATEST RAP...THIS FORCING IS A CONTRIBUTION FROM WARM ADVECTION IN THE LOW LEVELS / AND 700MB FRONTOGENESIS/ AND MID-UPPER LEVEL QG CONVERGENCE. THE FIRST SHORTWAVE WILL TRACK TOWARD THE NORTHERN FORECAST AREA THIS AFTERNOON AND ARRIVE AROUND 6-7 PM IN CLARK AND TAYLOR COUNTIES PER RAP FORECASTS AND TRACKING. THIS FIRST SHORTWAVE TROUGH WEAKENS AS IT MOVES IN PER THE CONSENSUS MODEL GUIDANCE AS THE SECOND WAVE INTENSIFIES AND DEEPENS. HOWEVER...THERE IS GUIDANCE /HRRR/ SOLUTIONS DIMINISHING THE WEATHER AS IT MOVES SOUTHEAST AND DRY AIR IN PLACE WILL DOMINATE. WITH CONSENSUS FORCING SWIPING A BAND OF SNOW IN THE EVENING AND CURRENT CONDITIONS...HAVE FORECAST THE SNOW TO MOVE IN DURING THE EVENING AND ACCUMULATE...MAINLY I-94 AND NORTH. THIS IS NOT A BIG CHANGE TO ONGOING FORECAST..BUT HIGHER CONFIDENCE. WILL LIKELY HIT THIS A BIT IN THE SOCIAL MEDIA AND SPECIAL WEATHER STATEMENTS WITH MORE TRAVEL THIS EVENING HAPPENING. SOME DIFFICULTY IN TRYING TO FIGURE OUT THE REMAINDER OF THE NIGHT AFTER MIDNIGHT...AHEAD OF THE SECOND SHORT WAVE TROUGH. IT APPEARS THE FRONTOGENESIS NEAR 700MB WILL BE STRONGER THAN THE FIRST SHORTWAVE AND WITH THE UPPER QG FORCING MAINLY OVER NRN WI /MODEL CONSENSUS/...SNOW SEEMS TO BE A GIVEN. BUT AS SHORTWAVE TROUGH 2 DEEPENS...THE FORCING SHIFTS INTO NORTHERN WI AND MAY SPREAD ITS SNOW NORTH OF TAYLOR COUNTY. FEEL FAIRLY CONFIDENT SNOW WILL OCCUR OVERNIGHT...BUT HAVE DECIDED TO MOVE IT NORTH WITH TIME AND LEAVE FLURRIES SOUTH TO I-94. THE SNOW RATIOS COULD BE QUITE HIGH WITH THIS SNOW WITH MOST OF THE SATURATED COLUMN IN THE DENDRITE GROWTH ZONE -12 TO -18C...THUS LOW QPF COULD PRODUCE AN INCH PRETTY EASY. MAINLY FLURRIES SHOULD REMAIN DURING THE EARLY MORNING THURSDAY WITH ROADS CLEANING UP FOR TRAVEL. SUN IS EXPECTED BY AFTERNOON. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 310 PM CST WED NOV 27 2013 A PERIOD OF QUIET WEATHER WITH SOME MODERATION IN TEMPERATURES BEGINNING FRIDAY...BUT A COLD START THAT MORNING UNDER HIGH PRESSURE AND CLEAR SKIES. IF A BIT MORE SNOW FALLS IN TAYLOR COUNTY TONIGHT ACROSS TAYLOR COUNTY...FRIDAY MORNING COULD BE NEAR ZERO. NEXT WEATHER SYSTEM SHIFTS ACROSS NORTHERN GREAT LAKES FRIDAY NIGHT AND SATURDAY WITH THE MORE FAVORABLE FORCING NORTH OF THE AREA. MAYBE SOME CLOUDS AND FLURRIES IN TAYLOR COUNTY BUT HAVE KEPT DRY FORECAST INTACT. SUNDAY THROUGH WEDNESDAY...LOW CONFIDENCE IN THIS PERIOD AS THE MODEL GUIDANCE HAS DIFFERENT EVOLUTIONS AND TIMING TO THE MAJOR READJUSTMENT OF THE LARGE SCALE PATTERN OVER NORTH AMERICA. MAJOR TROUGH AND COLD POOL OF AIR INVADE THE WESTERN CONUS WITH AN ASTOUNDING -3.5 TO -4 STANDARD DEVIATION BELOW NORMAL 850 MB TEMP IN THE WESTERN CONUS. BECAUSE OF THE SPREAD IN THE MODELS AND HOW ENERGY EJECTS OUT OF THE TROUGH...THE FORECAST HAS SMALL PRECIPITATION CHANCES MONDAY TO WEDNESDAY. THIS COULD BE A DRY PERIOD SHOULD THE 27.12Z ECMWF SOLUTION OCCUR...WHICH THE 27.12Z GFS TRENDED TOWARD...WITH MORE WEATHER LATER IN THE WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY MORNING) ISSUED AT 1134 PM CST WED NOV 27 2013 MID LEVEL FRONTOGENETIC BAND MOVING ACROSS CENTRAL WISCONSIN IS ONLY AVIATION IMPACT TONIGHT BUT THAT FEATURE IS QUICKLY PUSHING OFF TO THE EAST. MEANWHILE NEXT SHORT WAVE WILL BRING A COLD FRONT INTO THE AREA EARLY THANKSGIVING MORNING AND SHALLOW COLD AIR ADVECTION THROUGH MUCH OF THE DAY. EXTENSIVE STRATUS FIELD UPSTREAM SUGGESTS IDEA OF MORE CLOUDS IS ON TRACK WITH INVERSION SETTING UP. DRY AIRMASS ALOFT BUT IT WILL TAKE SOME TIME TO MIX OUT STRATUS FIELD LOCKED BELOW. GENERALLY CONDITIONS WILL REMAIN VFR BUT COULD SEE SOME MVFR CEILINGS AT TIME...ESPECIALLY NORTH OF INTERSTATE 90 THURSDAY MORNING. WILL BE OPTIMISTIC THAT CEILINGS WILL BREAK UP HEADING INTO THURSDAY EVENING AS RIDGE BUILDS IN. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE........SHEA SHORT TERM...BAUMGARDT LONG TERM...BAUMGARDT AVIATION...SHEA
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1032 AM MST THU NOV 28 2013 .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 332 AM MST THU NOV 28 2013 10Z SURFACE ANALYSIS SHOWS THE COLD FRONT BISECTING THE CWA FROM NORTHWEST TO SOUTHEAST WITH LIGHT WINDS THROUGHOUT THE AREA. HIGH CLOUDS ARE STREAMING OVERHEAD IN NORTHWEST FLOW WITH A STRATUS DECK CREEPING SOUTH-SOUTHWESTWARD ACROSS THE CENTRAL PLAINS AND TOWARD THE NORTHERN NEBRASKA PANHANDLE. CURRENT TRENDS COMBINED WITH NAM BUFKIT SOUNDINGS AND RECENT HRRR RUNS SUGGEST THAT THIS STRATUS DECK WILL IMPACT CHADRON AROUND SUNRISE AND MAY SNEAK INTO ALLIANCE AS WELL THROUGH THE MORNING. GUIDANCE ALSO SUGGESTS THE LOW CLOUDS WILL PERSIST THROUGH THE MORNING...AND WILL SCATTER OUT SLOWLY WITH INCREASED SOLAR INSOLATION. IN ADDITION...SOUTHEASTERLY WINDS WILL BECOME BREEZY ACROSS THE EASTERN PLAINS AS THE SFC HIGH SLIDES SOUTH-SOUTHEAST ACROSS THE CENTRAL PLAINS. THIS WILL ADVECT SOME LLVL MOISTURE INTO THE EASTERN PLAINS AND LIKELY CONTRIBUTE TO THE SLOWER MIXING OUT OF THE STRATUS. INCREASED CLOUD COVER FOR TODAY IN THIS AREA AS A RESULT...AND LOWERED MAX TEMPS A FEW DEGREES DUE TO THE MORE PERSISTENT CLOUD DECK. OTHERWISE...EXPECTING A DRY...CALM THANKSGIVING DAY WITH LIGHT WINDS AND CONTINUAL HIGH CIRRUS MOVING OVERHEAD FROM THE NORTHWEST. TONIGHT...A SHORTWAVE WILL MOVE EASTWARD ACROSS CENTRAL CANADA WHILE A SECOND WEAK WAVE WILL MOVE ACROSS COLORADO. THE COMBINATION OF FEATURES WILL DEEPEN THE LEESIDE SFC PRESSURE TROUGH...ALTHOUGH THE DEEPEST PRESSURE FALLS WILL REMAIN WELL REMOVED FROM THE REGION AND THEREFORE THE SFC PRESSURE GRADIENT WILL NOT BECOME VERY STRONG. STILL LOOKING AT 850/700 MB CAG-CPR GRADIENTS OF 30 DAM OR LESS BY EARLY FRIDAY MORNING. A LOOK AT A CROSS SECTION OF LAPSE RATES AND WINDS THROUGH THE WIND PRONE REGIONS ALONG AND WEST OF THE LARAMIE RANGE SHOWS THE INCREASE IN WINDS WITH THE STRENGTHENING GRADIENT...BUT THE INVERSION REMAINS NEAR THE GROUND EARLY FRIDAY MORNING WHICH SHOULD MINIMIZE GAP EFFECTS. THE INVERSION WILL LIFT JUST OFF THE SURFACE AND WILL REMAIN RELATIVELY WEAK THROUGH FRIDAY...BUT SHOULD BE STRONG ENOUGH TO PRODUCE MODERATE GRADIENT/GAP WINDS THROUGH FRIDAY NIGHT. LOOKING AT SUSTAINED WEST-SOUTHWEST WINDS IN THIS AREA ON AVERAGE OF 25 TO 35 MPH WITH A FEW PERIODS OF STRONGER WINDS IN THE MORNING HOURS AS THE INVERSION BEGINS TO LIFT. GUSTS SHOULD REMAIN WITHIN THE 50 TO 55 MPH ZONE AS WINDS JUST OFF THE SURFACE ARE PROGGED TO ONLY BE AS HIGH AS 40 KTS. LASTLY FOR FRIDAY...LITTLE CHANGE TO THE AIRMASS OUT IN THE FAR WESTERN PORTIONS OF THE FORECAST AREA ON FRIDAY MORNING SUGGESTS A RETURN OF STRATUS AND PATCHY FOG IN FAR SOUTHWESTERN CARBON COUNTY. WITH LITTLE CHANGE IN THE SYNOPTIC PATTERN ON SATURDAY...EXPECT MODERATE WINDS TO CONTINUE THROUGH AT LEAST SATURDAY AFTERNOON. BREEZY WEST-NORTHWEST WINDS WILL EXPAND WESTWARD AND JUST TO THE LEE OF THE MOUNTAINS DURING THE AFTERNOON HOURS AS THE INVERSION LIFTS...WHICH WILL WARM TEMPS ACROSS THE EASTERN PLAINS BACK INTO THE 50S FOR FRIDAY AND SATURDAY DUE TO DOWNSLOPE WARMING EFFECTS. A WEAK SHORTWAVE MOVING TOWARD THE REGION ON SATURDAY AFTERNOON WILL BRING WITH IT A PLUME OF LOW-MID LEVEL MOISTURE. COULD SEE A FEW OROGRAPHIC SNOW SHOWERS OVER THE MOUNTAINS IN THE LATE AFTERNOON AS THIS WEAK ENERGY AND MOISTURE MOVE OVERHEAD. .LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 332 AM MST THU NOV 28 2013 VERY DEFINITE PATTERN CHANGE CONTINUES TO BE ADVERTISED IN THE LONG TERM. LOOKS VERY COLD AND WET FOR NEXT WEEK. STARTING OFF SATURDAY NIGHT...LOOKS LIKE OUR WIND PRONE AREAS WILL BE WINDY AS GFS 700MB WINDS ARE UP AROUND 45KTS SATURDAY NIGHT. AFTER A DECREASE IN WINDS DURING THE DAY SUNDAY...THEY PICK UP AGAIN SUNDAY NIGHT...THOUGH NOT AS STRONG AS PREVIOUS MODEL RUNS WERE ADVERTISING. RIGHT NOW...THE NEW GFS WINDS ARE RIGHT AROUND 45-50KTS SUNDAY EVENING INTO MONDAY. CRAIG TO CASPER 700MB HEIGHT GRADIENT STILL TIGHT THOUGH...RIGHT AROUND 70MTRS...SO IF THIS HOLDS TRUE...WE WILL PROBABLY NEED SOME WIND HEADLINES FOR THIS TIME FRAME. MODELS STILL ADVERTISING A DRASTIC CHANGE IN THE WEATHER TUESDAY AS A STRONG PACIFIC LOW PRESSURE SYSTEM MOVES INTO THE PACNW. FRONT DOES NOT MAKE IT INTO SOUTHEAST WYOMING UNTIL WEDNESDAY MORNING. MODELS CONTINUE TO SHOW THIS FRONT STALLING OVER NORTHERN COLORADO AND PERSISTING THROUGH THE REMAINDER OF THE WEEK. 700MB TEMPERATURES ARE QUITE COLD BEHIND THE FRONT. GFS SHOWING -18 TO -20C WHILE NEW ECMWF RUN SHOWING -16 TO -18C. GOING TO BE QUITE COLD THROUGH THE REMAINDER OF THE WEEK. HIGHS THURSDAY/FRIDAY MAY ONLY BE IN THE TEENS WITH LOWS CLOSE TO ZERO AT MANY LOCATIONS. && .AVIATION...(FOR THE 18Z TAFS) STRATUS ACROSS SOUTH DAKOTA AND CENTRAL/EASTERN NEBRASKA IS NOT EXPECTED TO MOVE INTO THE NORTHERN NE PANHANDLE THIS AFTERNOON...ALTHOUGH IT IS CLOSE TO KCDR AT THIS HOUR. WILL CONTINUE TO MONITOR THE WESTWARD PROGRESSION OF THIS LOW CIG STRATUS. OTHERWISE...LIGHT WINDS AND VFR CONDITIONS WILL CONTINUE ACROSS SOUTHEAST WYOMING AND WESTERN NEBRASKA THROUGH TONIGHT. && .FIRE WEATHER... ISSUED AT 332 AM MST THU NOV 28 2013 NO FIRE WEATHER CONCERNS ANTICIPATED THROUGH THE NEAR TERM. MILD AND DRY CONDITIONS WILL CONTINUE ACROSS THE DISTRICT OVER THE NEXT FEW DAYS WITH DAYTIME TEMPS AVERAGING IN THE 40S AND 50S DEGREES...WITH COOLER READINGS OVER THE HIGHER TERRAIN. MINIMUM HUMIDITIES WILL BE AT OR ABOVE 30 PERCENT EACH AFTERNOON. MODERATE WINDS ARE EXPECTED ON FRIDAY AND SATURDAY IN THE WIND PRONE REGIONS ALONG AND WEST OF THE LARAMIE RANGE WITH SUSTAINED SPEEDS BETWEEN 25 AND 40 MPH AND GUSTS AROUND 50 MPH AT TIMES. A STRONG WEATHER SYSTEM WILL BEGIN TO TAKE SHAPE LATE THIS WEEKEND INTO THE EARLY PART OF NEXT WEEK...LIKELY BRINGING STRONGER WINDS...COLDER TEMPERATURES AND AN INCREASED CHANCE FOR ACCUMULATING SNOWS. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...RJM LONG TERM...CLAYCOMB AVIATION...TJT FIRE WEATHER...RJM
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
333 AM MST THU NOV 28 2013 .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 332 AM MST THU NOV 28 2013 10Z SURFACE ANALYSIS SHOWS THE COLD FRONT BISECTING THE CWA FROM NORTHWEST TO SOUTHEAST WITH LIGHT WINDS THROUGHOUT THE AREA. HIGH CLOUDS ARE STREAMING OVERHEAD IN NORTHWEST FLOW WITH A STRATUS DECK CREEPING SOUTH-SOUTHWESTWARD ACROSS THE CENTRAL PLAINS AND TOWARD THE NORTHERN NEBRASKA PANHANDLE. CURRENT TRENDS COMBINED WITH NAM BUFKIT SOUNDINGS AND RECENT HRRR RUNS SUGGEST THAT THIS STRATUS DECK WILL IMPACT CHADRON AROUND SUNRISE AND MAY SNEAK INTO ALLIANCE AS WELL THROUGH THE MORNING. GUIDANCE ALSO SUGGESTS THE LOW CLOUDS WILL PERSIST THROUGH THE MORNING...AND WILL SCATTER OUT SLOWLY WITH INCREASED SOLAR INSOLATION. IN ADDITION...SOUTHEASTERLY WINDS WILL BECOME BREEZY ACROSS THE EASTERN PLAINS AS THE SFC HIGH SLIDES SOUTH-SOUTHEAST ACROSS THE CENTRAL PLAINS. THIS WILL ADVECT SOME LLVL MOISTURE INTO THE EASTERN PLAINS AND LIKELY CONTRIBUTE TO THE SLOWER MIXING OUT OF THE STRATUS. INCREASED CLOUD COVER FOR TODAY IN THIS AREA AS A RESULT...AND LOWERED MAX TEMPS A FEW DEGREES DUE TO THE MORE PERSISTENT CLOUD DECK. OTHERWISE...EXPECTING A DRY...CALM THANKSGIVING DAY WITH LIGHT WINDS AND CONTINUAL HIGH CIRRUS MOVING OVERHEAD FROM THE NORTHWEST. TONIGHT...A SHORTWAVE WILL MOVE EASTWARD ACROSS CENTRAL CANADA WHILE A SECOND WEAK WAVE WILL MOVE ACROSS COLORADO. THE COMBINATION OF FEATURES WILL DEEPEN THE LEESIDE SFC PRESSURE TROUGH...ALTHOUGH THE DEEPEST PRESSURE FALLS WILL REMAIN WELL REMOVED FROM THE REGION AND THEREFORE THE SFC PRESSURE GRADIENT WILL NOT BECOME VERY STRONG. STILL LOOKING AT 850/700 MB CAG-CPR GRADIENTS OF 30 DAM OR LESS BY EARLY FRIDAY MORNING. A LOOK AT A CROSS SECTION OF LAPSE RATES AND WINDS THROUGH THE WIND PRONE REGIONS ALONG AND WEST OF THE LARAMIE RANGE SHOWS THE INCREASE IN WINDS WITH THE STRENGTHENING GRADIENT...BUT THE INVERSION REMAINS NEAR THE GROUND EARLY FRIDAY MORNING WHICH SHOULD MINIMIZE GAP EFFECTS. THE INVERSION WILL LIFT JUST OFF THE SURFACE AND WILL REMAIN RELATIVELY WEAK THROUGH FRIDAY...BUT SHOULD BE STRONG ENOUGH TO PRODUCE MODERATE GRADIENT/GAP WINDS THROUGH FRIDAY NIGHT. LOOKING AT SUSTAINED WEST-SOUTHWEST WINDS IN THIS AREA ON AVERAGE OF 25 TO 35 MPH WITH A FEW PERIODS OF STRONGER WINDS IN THE MORNING HOURS AS THE INVERSION BEGINS TO LIFT. GUSTS SHOULD REMAIN WITHIN THE 50 TO 55 MPH ZONE AS WINDS JUST OFF THE SURFACE ARE PROGGED TO ONLY BE AS HIGH AS 40 KTS. LASTLY FOR FRIDAY...LITTLE CHANGE TO THE AIRMASS OUT IN THE FAR WESTERN PORTIONS OF THE FORECAST AREA ON FRIDAY MORNING SUGGESTS A RETURN OF STRATUS AND PATCHY FOG IN FAR SOUTHWESTERN CARBON COUNTY. WITH LITTLE CHANGE IN THE SYNOPTIC PATTERN ON SATURDAY...EXPECT MODERATE WINDS TO CONTINUE THROUGH AT LEAST SATURDAY AFTERNOON. BREEZY WEST-NORTHWEST WINDS WILL EXPAND WESTWARD AND JUST TO THE LEE OF THE MOUNTAINS DURING THE AFTERNOON HOURS AS THE INVERSION LIFTS...WHICH WILL WARM TEMPS ACROSS THE EASTERN PLAINS BACK INTO THE 50S FOR FRIDAY AND SATURDAY DUE TO DOWNSLOPE WARMING EFFECTS. A WEAK SHORTWAVE MOVING TOWARD THE REGION ON SATURDAY AFTERNOON WILL BRING WITH IT A PLUME OF LOW-MID LEVEL MOISTURE. COULD SEE A FEW OROGRAPHIC SNOW SHOWERS OVER THE MOUNTAINS IN THE LATE AFTERNOON AS THIS WEAK ENERGY AND MOISTURE MOVE OVERHEAD. .LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 332 AM MST THU NOV 28 2013 VERY DEFINITE PATTERN CHANGE CONTINUES TO BE ADVERTISED IN THE LONG TERM. LOOKS VERY COLD AND WET FOR NEXT WEEK. STARTING OFF SATURDAY NIGHT...LOOKS LIKE OUR WIND PRONE AREAS WILL BE WINDY AS GFS 700MB WINDS ARE UP AROUND 45KTS SATURDAY NIGHT. AFTER A DECREASE IN WINDS DURING THE DAY SUNDAY...THEY PICK UP AGAIN SUNDAY NIGHT...THOUGH NOT AS STRONG AS PREVIOUS MODEL RUNS WERE ADVERTISING. RIGHT NOW...THE NEW GFS WINDS ARE RIGHT AROUND 45-50KTS SUNDAY EVENING INTO MONDAY. CRAIG TO CASPER 700MB HEIGHT GRADIENT STILL TIGHT THOUGH...RIGHT AROUND 70MTRS...SO IF THIS HOLDS TRUE...WE WILL PROBABLY NEED SOME WIND HEADLINES FOR THIS TIME FRAME. MODELS STILL ADVERTISING A DRASTIC CHANGE IN THE WEATHER TUESDAY AS A STRONG PACIFIC LOW PRESSURE SYSTEM MOVES INTO THE PACNW. FRONT DOES NOT MAKE IT INTO SOUTHEAST WYOMING UNTIL WEDNESDAY MORNING. MODELS CONTINUE TO SHOW THIS FRONT STALLING OVER NORTHERN COLORADO AND PERSISTING THROUGH THE REMAINDER OF THE WEEK. 700MB TEMPERATURES ARE QUITE COLD BEHIND THE FRONT. GFS SHOWING -18 TO -20C WHILE NEW ECMWF RUN SHOWING -16 TO -18C. GOING TO BE QUITE COLD THROUGH THE REMAINDER OF THE WEEK. HIGHS THURSDAY/FRIDAY MAY ONLY BE IN THE TEENS WITH LOWS CLOSE TO ZERO AT MANY LOCATIONS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 332 AM MST THU NOV 28 2013 SOME CONCERN FOR THE NORTHERN NEBRASKA PANHANDLE AS LATEST 11-3.9U SATELLITE IMAGERY SHOWING LOW STRATUS MOVING SOUTHWEST OUT OF SOUTH DAKOTA. LATEST HRRR MODEL BRINGS IFR CONDITIONS INTO KCDR AND KEEPS IT IN THROUGH 18Z. WILL BE ADJUSTING THE 12Z KCDR TAF BASED ON THIS AND THE SATELLITE TRENDS ONCE THE STRATUS GETS CLOSER. && .FIRE WEATHER... ISSUED AT 332 AM MST THU NOV 28 2013 NO FIRE WEATHER CONCERNS ANTICIPATED THROUGH THE NEAR TERM. MILD AND DRY CONDITIONS WILL CONTINUE ACROSS THE DISTRICT OVER THE NEXT FEW DAYS WITH DAYTIME TEMPS AVERAGING IN THE 40S AND 50S DEGREES...WITH COOLER READINGS OVER THE HIGHER TERRAIN. MINIMUM HUMIDITIES WILL BE AT OR ABOVE 30 PERCENT EACH AFTERNOON. MODERATE WINDS ARE EXPECTED ON FRIDAY AND SATURDAY IN THE WIND PRONE REGIONS ALONG AND WEST OF THE LARAMIE RANGE WITH SUSTAINED SPEEDS BETWEEN 25 AND 40 MPH AND GUSTS AROUND 50 MPH AT TIMES. A STRONG WEATHER SYSTEM WILL BEGIN TO TAKE SHAPE LATE THIS WEEKEND INTO THE EARLY PART OF NEXT WEEK...LIKELY BRINGING STRONGER WINDS...COLDER TEMPERATURES AND AN INCREASED CHANCE FOR ACCUMULATING SNOWS. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...RJM LONG TERM...CLAYCOMB AVIATION...CLAYCOMB FIRE WEATHER...RJM
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
337 AM CST SAT NOV 30 2013 .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 337 AM CST SAT NOV 30 2013 00Z MODELS INITIALIZED WITH MINIMAL ERRORS AND ARE IN GOOD AGREEMENT THROUGH SUNDAY. THE CHALLENGE FOR TODAY WILL BE TEMPERATURES AND CLOUD COVER. THE CHALLENGE FOR SUNDAY WILL BE -SN CHANCES. TODAY-TONIGHT...WEAK COLD FRONT WILL BE THROUGH THE REGION WHICH SHOULD LEAD TO SLIGHTLY COOLER TEMPERATURES THAN YESTERDAY. THE MID-LEVEL CLOUDS ALONG AND AHEAD OF THIS FEATURE WILL MOVE SOUTH...BUT WILL NEED TO WATCH THE LOW-LEVEL CIGS APPROACHING FROM THE NORTH. 06Z RAP IS MOST AGGRESSIVE BRINGING THESE CIGS INTO THE ENTIRE FA...WHILE MOST OTHER GUIDANCE SUGGESTS ONLY PORTIONS OF NW MN WILL BE AFFECTED. WILL SIDE WITH THE MAJORITY...AND TAKE A CLOSER LOOK AT THE 7AM UPDATE. SUNDAY...00Z MODELS HAVE SLOWED THE SHORTWAVE BRINGING -SN CHANCES...ADJUSTED POPS ACCORDINGLY. MUCH OF SUNDAY SHOULD BE DRY (UNTIL THE EVENING HOURS). .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 337 AM CST SAT NOV 30 2013 SUNDAY NIGHT-MONDAY NIGHT...00Z MODELS BEGIN TO DIVERGE...WITH THE ECMWF/GEM/UKMET DIGGING THE UPPER LOW INTO THE NW CONUS BY 12Z TUE...AND THE NAM/GFS BRINGING THIS FEATURE INTO MONTANA/WESTERN DAKOTAS. THE ECMWF/GEM/UKMET HAVE BEEN THE MORE CONSISTENT MODELS...AND ARE SUPPORTED BY ENSEMBLES (WILL FOLLOW FOR FORECAST DETAILS). THERE WILL BE A COUPLE LEAD SHORTWAVES EJECTING FROM THE MAIN UPPER TROUGH. THE FIRST WILL MOVE THROUGH THE REGION SUNDAY NIGHT...AND THE SECOND MONDAY AFTERNOON/NIGHT. SINCE THERE HAVE BEEN A FEW MODEL RUNS INDICATING THESE FEATURES...WILL INCREASE POPS TO LIKELY AND ATTEMPT TO TIME THESE FEATURES THROUGH THE REGION. THE FIRST WAVE IS WEAKER...AND SHOULD HAVE LESS AVAILABLE MOISTURE. MESOSCALE FORCING IS ALSO WEAK...SO UP TO AN INCH OF SNOWFALL APPEARS POSSIBLE (MAYBE 2 INCHES). THE SECOND WAVE IS STRONGER...WITH MORE AVAILABLE MOISTURE (PWATS APPROACHING 0.5 INCHES). MODELS INDICATE A DEFINED CIRCULATION AT 850MB (AND A WEAK 700MB LOW) PROPAGATING FROM NW ND INTO SE ND ON MONDAY...LOSING DEFINITION MONDAY NIGHT AS IT PROPAGATES FURTHER TO THE SE. ASSOCIATED WARM AIR ADVECTION/DEFORMATION COMBINED WITH THE 0.5 INCH PWATS SHOULD LEAD TO A FEW INCHES OF SNOWFALL. MODELS INDICATE 0.25-0.40 INCHES QPF ACROSS ALL BUT THE NE FA...AND COMBINED WITH 12:1-13:1 SNOW RATIOS WOULD LEAD TO AN AREA OF 3-5 INCHES OF SNOW. P-TYPE WILL BE ALL SNOW IF THE EXPECTED SOLUTION VERIFIES. THE NAM/SREF/GFS HAVE WARMER MID-LEVEL TEMPERATURES SINCE THE UPPER WAVE IS CLOSER TO THE REGION (LOW LEVEL SOUTHERLY FLOW IS STRONGER)...AND WOULD LEAD TO FZRA/RA POTENTIAL (BUT THIS PROBABILITY SEEMS VERY LOW ATTM). TUESDAY-FRIDAY...A VERY WINTRY PERIOD IS IN STORE...WITH THE MAIN FOCUS INITIALLY BEING SNOW POTENTIAL THROUGH MID-WEEK FOLLOWED BY A COLD ARCTIC AIR MASS SPILLING SOUTH. MODEL SPREAD CONTINUES TO BE SIGNIFICANT...ALTHOUGH THE ECMWF HAS SHOWN BETTER CONSISTENCY OVER THE PAST FEW RUNS...SO HAVE TRENDED A BIT IN THAT DIRECTION. THE 00Z GFS/ECMWF BOTH BRING THE UPPER TROUGH EASTWARD INTO THE PLAINS WED/THU. HOWEVER...A CHALLENGE CONTINUES TO BE TIMING OF EMBEDDED WAVES. THE ECMWF REMAINS DEEPEST AND FARTHEST WEST WITH SFC LOW DEVELOPMENT FROM THE CENTRAL PLAINS NORTHEAST INTO ONTARIO IN CONJUNCTION WITH A STRONG SHORTWAVE TROUGH ASSOCIATED WITH THE LIFTING UPPER LOW...WHILE THE GFS IS MORE PROGRESSIVE WITH A WEAKER SFC LOW ASSOCIATED WITH A LEAD WAVE. THUS...THE ECMWF AND TO A LESSER EXTENT THE GEM ARE MORE AGGRESSIVE WITH QPF. THE 500 MB GFS ENSEMBLE MEAN HEIGHT FIELD GENERALLY SUPPORTS THE ECMWF BROADLY. CONFIDENCE STILL IS RATHER LOW REGARDING THE PLACEMENT AND MAGNITUDE OF SNOWFALL...ALTHOUGH THE MID-WEEK PERIOD WILL CONTINUE TO BEAR WATCHING FOR ACCUMULATING SNOWFALL. ARCTIC AIR WILL BLAST SOUTH DURING THE LATTER PART OF THE WEEK INTO NEXT WEEKEND. THE ECMWF CONTINUES TO INDICATE 925 MB TEMPS DOWN TO -20 TO -25C THURSDAY/FRIDAY BEHIND INITIAL SURGE OF COLD ADVECTION. BLUSTERY WINDS WILL COMBINE WITH VERY COLD TEMPS TO PRODUCE POTENTIALLY HAZARDOUS WIND CHILLS AT TIMES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1146 PM CST FRI NOV 29 2013 SATELLITE AND SURFACE OBS INDICATE CIGS ABOVE 9 THOUSAND FT WERE LOCATED OVER NORTHERN ND AND PARTS OF SOUTHEAST ND. MID LEVEL DECK SHOULD CONTINUE TO MOVE SOUTHEAST THROUGH THE AREA TONIGHT AND SAT. ALSO CLEAR SLOT OVER SOUTHERN SASK AND SOUTHWEST MAN CONTINUES TO MOVE SOUTHEAST. ELSEWHERE CIGS AROUND 35 HUNDRED FT WERE LOCATED OVER THE FAR NORTHEAST ZONES AND MAY CONTINUE THERE FOR THE REST OF THE NIGHT. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ SHORT TERM...TG LONG TERM...TG/MAKOWSKI AVIATION...HOPPES
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
349 AM CST SAT NOV 30 2013 .SHORT TERM...TODAY THROUGH MONDAY CHANCES FOR PRECIPITATION AS WELL AS P-TYPE WILL BE THE FORECAST CHALLENGES. A WEAK MID LEVEL SHORT WAVE CURRENTLY OVER MONTANA WILL TRACK SOUTHEASTWARD ACROSS THE REGION TODAY...BRINGING PARTLY CLOUDY SKIES TO THE CWA. THE PAST FEW RUNS OF THE RUC AND THE NSSL WRF BOTH SHOW SOME LIGHT RAIN FOR THE FAR NW PORTION OF THE CWA...PERHAPS REACHING KMBG BY THIS AFTERNOON. THUS HAVE ADDED A LOW POP. ANOTHER MID LEVEL SHORT WAVE AND FRONTAL BOUNDARY WILL TRACK ACROSS THE REGION ON SUNDAY. MODELS HAVE SIGNIFICANTLY SLOWED DOWN THE PROGRESSION OF THE TROUGH...WITH PCPN NOT REACHING THE JAMES RIVER VALLEY UNTIL AFTER 18Z. IT STILL APPEARS AS THOUGH THE LEADING EDGE OF THE PCPN WILL FALL AS ALL SNOW. HOWEVER WITH WAA QUICKLY PUSHING IN ON THE BACK SIDE...THE SNOW WILL TRANSITION OVER TO ALL RAIN. THIS SYSTEM DOES NOT CONTAIN A GREAT DEAL OF LOW LEVEL MOISTURE SO WILL MAINTAIN CHC POP ALONG THE ND/SD BORDER FOR NOW. A MUCH STRONGER STORM SYSTEM WILL BEGIN IMPACTING THE REGION ON MONDAY. HOWEVER MODEL ARE NOT IN A REAL GOOD AGREEMENT WITH THE OVERALL PLACEMENT OF THIS MID LEVEL CLOSED LOW...WHICH LEADS TO A LOW FORECASTER CONFIDENCE. EVEN WITH A DISAGREEMENT ON THE PLACEMENT THERE IS A GENERAL CONSENSUS THAT TEMPERATURES WILL BE WARM ENOUGH TO SUPPORT A MOSTLY RAIN EVENT. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY STILL NOT A LOT OF CONFIDENCE WITH THE FINER DETAILS WITHIN THE EXTENDED...THOUGH TWO GENERAL TRENDS CAN BE EXPECTED. THE FIRST WILL BE THE INFLUENCE OF A BROAD UPPER TROF AND EMBEDDED SHORTWAVES MOVING ACROSS THE NORTHERN TIER CONUS. MOST OF THE PRECIPITATION WILL BE ASSOCIATED WITH AN H7 LOW THAT LOOKS TO TRACK ACROSS NORTH DAKOTA/MINNESOTA...THOUGH IT MAY PIVOT THROUGH WESTERN SOUTH DAKOTA DEPENDING ON THE MODEL. THIS TRACK SUGGESTS NORTH DAKOTA WILL RECEIVE THE MAJORITY OF PRECIPITATION WITHIN THE WARM ADVECTION BAND AND ANY TROWAL BASED WRAP AROUND. THE GFS IS GENERALLY WEAKER WITH SIGNIFICANTLY LOWER PRECIPITATION POTENTIAL. THE ECMWF IS STRONGER...WITH A MORE SOUTHERLY TRACK...AND STRONGER WINDS WITH POTENTIALLY MORE IMPACTS TO THE CWA. THE SECOND FEATURE WILL BE ANOMALOUSLY COLD AIR POURING INTO THE REGION. TIMING DIFFERENCES CONTINUE BETWEEN THE GFS AND ECMWF...VARYING BETWEEN TUESDAY AND WEDNESDAY RESPECTIVELY. BOTH MODELS RESOLVE THE COLD POOL WITH SIMILAR INTENSITY AND DURATION...AS IT WILL COME TO DOMINATE THE WEATHER THROUGH THE END OF THE WORK WEEK. UNFORTUNATELY...BOTH MODELS HAVE BEEN REASONABLY CONSISTENT WITH THEIR INDIVIDUAL TRENDS. WILL CONTINUE TO BROADBRUSH THE FIRST FEW PERIODS OF THE EXTENDED WITH CHANCE POPS/SNOW UNTIL MODELS ENTER BETTER ALIGNMENT. && .AVIATION... 06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD. LIGHT WINDS WILL PERSIST OVERNIGHT BEFORE SWITCHING TO NORTH-NORTHWEST AROUND 5 TO 10 KNOTS ON SATURDAY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...SD LONG TERM...CONNELLY AVIATION...DORN WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1226 AM EST SAT NOV 30 2013 .SYNOPSIS... HIGH PRESSURE WILL BE ACROSS THE REGION THROUGH THE WEEKEND WHILE A SERIES OF UPPER LEVEL DISTURBANCES PASS NORTH OF THE REGION. A WEAK DISTURBANCE WILL PASS THROUGH THE AREA ON MONDAY WHILE AN AREA OF LOW PRESSURE MOVES NORTH ALONG THE COAST. THE NEXT SYSTEM TO BRING PRECIPITATION TO MOST OF OUR REGION WILL ARRIVE THURSDAY INTO FRIDAY. && .NEAR TERM /THROUGH TODAY/... AS OF 920 PM EST FRIDAY ADJUSTED OVERNIGHT MIN TEMPS DOWN A FEW DEGREES AS SKIES REMAIN CLEAR SO FAR WITH CALMS WINDS NEARLY EVERYWHERE. STILL HOLDING TO IDEA OF LOW CLOUDS DRIFTING SW ACROSS THE MOUNTAINS BY THE EARLY MORNING HOURS AS SHOWN BY LATEST RAP AND NAM MODELS WHICH WOULD ARREST THE DOWNWARD TRAJECTORY IN TEMPS SOMEWHAT. LOWERED WINDS SLIGHTLY AS WELL BUT OTHERWISE NO SUBSTANTIVE CHANGES. PREVIOUS VALID DISCUSSION AS OF 300 PM EST FRIDAY... A WEAK UPPER LEVEL DISTURBANCE WILL PROGRESS THROUGH THE GREAT LAKES REGION TONIGHT INTO SATURDAY. SURFACE HIGH PRESSURE WILL BECOME CENTERED OVER NEW ENGLAND BY SATURDAY MORNING...AND ITS ASSOCIATED RIDGE AXIS WILL TRAIL SOUTHWEST ALONG THE LEE OFF THE APPALACHIANS. LOW LEVEL MOISTURE HAS BEEN ABUNDANT TODAY FROM NORTHERN WEST VIRGINIA...NORTH INTO PENNSYLVANIA. TWO WEATHER PATTERNS WILL CONTRIBUTE TO INCREASING CLOUD COVER TONIGHT INTO SATURDAY. FIRST...THE ADVANCING SYSTEM THROUGH THE GREAT LAKES REGION HAS ALREADY ALLOWED FOR SOME DOWNSTREAM ADVANCEMENT OF MID TO HIGH LEVEL CLOUD COVER OVER PARTS OF INDIANA AND KENTUCKY. THIS CLOUD COVER WILL PROGRESS INTO OUR REGION OVERNIGHT WITH INCREASING COVERAGE THROUGH SATURDAY. THE GREATEST CONCENTRATION WILL OVER THE NORTHERN PARTS OF THE FORECAST AREA. SECOND...BOTH 12Z/7AM GFS AND TO A GREATER DEGREE THE 12Z/7AM NAM ARE DEPICTING A SOUTHERN ADVANCEMENT OF THE WV/MD/PA MOISTURE ALONG THE LEE OF THE APPALACHIANS OVERNIGHT. THIS MOISTURE IS DEPICTED AS BEING SHALLOW WITHIN ROUGHLY THE 925-900 MB LAYER. 925 MB WINDS WILL BE COMPARABLE TO THE ORIENTATION TYPICALLY ASSOCIATED WITH ONSET OF A HIGH PRESSURE RIDGE ALONG COMMON DAMMING AREA. 925 MB WINDS WILL GRADUALLY VEER OVERNIGHT TO NORTHEAST AND THEN TO THE EAST. THE WV/MD/PA MOISTURE IS PROGGED TO GET CAUGHT UP IN THIS FLOW AND EVENTUALLY TAKE AN UPSLOPE ORIENTATION TO THE BLUE RIDGE. THIS WILL HELP IN THE FORMATION OF LOW LEVEL CLOUD COVER ACROSS THOSE REGIONS OF THE FORECAST AREA GENERALLY ALONG AND WEST OF THE CREST OF THE BLUE RIDGE. THE WINDOW OF BEST COVERAGE WILL BE FROM ROUGHLY 300 AM SATURDAY THROUGH 10AM SATURDAY. PAST THIS POINT THE NOCTURNAL INVERSION WILL HAVE ERODED AND THE CLOUDS BEGIN TO DISSIPATE. FOR LOWS TONIGHT...I HAVE FAVORED NUMBERS AT OR SLIGHTLY ABOVE GUIDANCE IN THOSE AREAS THAT WILL EXPERIENCE THE BULK OF THE AFOREMENTIONED CLOUD COVER. FOR SATURDAY...THE REGION WILL STILL BE CONTENDING WITH THE MID TO HIGH LEVEL CLOUD COVER...AGAIN PRIMARILY IN THE NORTH...IN ASSOCIATION WITH PASSING SHORTWAVE TROUGH TO OUR NORTH. CLOSER TO THE SURFACE...THE 925 MB FLOW BECOMES EASTERLY THE WHOLE WAY TO THE COAST. THIS WILL ALLOW ATLANTIC MOISTURE TO PROGRESS INTO AT LEAST THE PIEDMONT REGION OF THE FORECAST AREA BY THE LATE AFTERNOON. WILL BE SHOWING INCREASING CLOUD COVER IN THIS REGION TO ACCOUNT FOR THIS. HAVE NOT DEVIATED TOO FAR FROM A BLEND OF THE GFS AND NAM MOS FOR HIGH TEMPERATURES. && .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... AS OF 240 PM EST FRIDAY... ZONAL FLOW ALOFT OVER THE MID APPALACHIAN AND MID ATLANTIC REGION WILL GRADUALLY BE REPLACED BY MEAN TROFING OVER THE EASTERN PORTION OF THE NATION BY THE END OF THE SHORT TERM PERIOD AS A SERIES OF WEAK SHORT WAVE TROFS EMBEDDED IN NORTHERN STREAM HELPS TO SLOWLY BUCKLE UPPER FLOW. PRESENCE OF WEAK SURFACE HIGH PRESSURE...NEGLIGIBLE THERMAL ADVECTION...AND PRESENCE OF HIGH AND OCCASIONALLY MID LEVEL CLOUDS UNDER REGION OF CHANNELIZED VORTICITY SHOULD MAINTAIN RATHER UNEVENTFUL WEATHER OVER THE BLACKSBURG FORECAST AREA SATURDAY NIGHT THROUGH SUNDAY NIGHT WITH SOMEWHAT MODERATED DIURNAL TEMPERATURE PROFILE. NIGHTTIME LOWS EXPECTED TO RANGE FROM THE MID 20S TO LOWER 30S IN MOST AREAS...WITH COOLEST READINGS IN THE DEEPER VALLEYS... AND MILDER READINGS ACROSS THE RIDGELINES AND NC FOOTHILLS. DAYTIME HIGHS ON SATURDAY EXPECTED TO RANGE FROM THE LOWER TO MID 40S IN THE MOUNTAINS TO LOWER 50S ACROSS THE PIEDMONT. A MORE SIGNIFICANT SHORT WAVE IS EXPECTED TO AMPLIFY UPPER FLOW AS IT DIVES EAST-SOUTHEAST OUT OF THE MISSISSIPPI VALLEY ON MONDAY...REACHING THE EAST COAST BY LATE MONDAY NIGHT. BACKING FLOW ALOFT WILL HELP STRENGTHEN BAROCLINIC ZONE ALONG THE SOUTHEAST COAST...RESULTING IN CYCLOGENESIS WITH SURFACE LOW EXPECTED TO DEVELOP AND STRENGTHEN ALONG THE COAST BY LATE IN SHORT TERM PERIOD. MID-RANGE MODELS NOT YET CONSISTENTLY RESOLVING DEVELOPMENT... PLACEMENT...AND TIMING OF THIS FEATURE...YET MOST IMPLY THAT FLOW WILL NOT AMPLIFY SUFFICIENTLY OR SOON ENOUGH TO ALLOW DEVELOPING AREA OF PRECIPITATION IN ISENTROPIC ZONE TO SIGNIFICANTLY THREATEN BLACKSBURG AREA OF CONCERN BEFORE MOVING OFF THE EAST. CONSIDERING THAT PAST COUPLE OF MODEL TRENDS HAVE BECOME A BIT MORE BULLISH IN AMPLIFICATION OF THIS SYSTEM...WILL CONTINUE TO MAINTAIN A LOW THREAT FOR PRECIPITATION IN MOST AREAS MONDAY AFTERNOON INTO MONDAY NIGHT...WITH HIGHEST THREAT FOR PRECIPITATION EXPECTED TO BE RESTRICTED TO MAINLY NORTHWESTERN MOUNTAINS WHERE LOCAL UPSLOPING WILL BE MAXIMIZED. CONSIDERING THERMAL PROFILE...ANY PRECIPITATION ON MONDAY WILL LIKELY COME IN THE FORM OF SPOTTY LIGHT SHOWERS...HOWEVER INCREASING COLD ADVECTION ON BACKSIDE OF COASTAL LOW WILL LIKELY BE/BECOME SUFFICIENT ENOUGH TO ALLOW CHANGEOVER TO SNOW OR RAIN/SNOW MIX IN MOUNTAINS ON MONDAY NIGHT. FURTHER EAST...EVEN IF COASTAL LOW IS ABLE TO CRANK UP FAST ENOUGH TO PUSH PRECIPITATION UNDER DEVELOPING DEFORMATION ZONE WESTWARD INTO EASTERN PIEDMONT COUNTIES...THERMAL PROFILE IN THAT AREA LIKELY TO REMAIN ABOVE FREEZING (HENCE ONLY A COLD RAIN) UNTIL SYSTEM LIFTS AWAY FROM THE AREA BY/BEFORE DAYBREAK TUESDAY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 300 PM EST FRIDAY... THE BEGINNING OF THE LONG TERM PERIOD WILL BEGIN WITH SOME UPSLOPE PRECIPITATION ACROSS THE MOUNTAINS. BOTH THE GFS AND THE ECMWF SHOW PRECIPITATION THROUGH ABOUT 6Z WEDNESDAY. LIKELY WILL BE SNOW SHOWERS ACROSS WESTERN GREENBRIER WITH A MIX OF RAIN AND SNOW ACROSS LOWER ELEVATION MOUNTAIN AREAS. MODELS ALSO AGREE THAT THERE WILL CONTINUE TO BE A GENERAL WARMING TREND AS 500 MB HEIGHT LEVELS CONTINUE TO RISE THROUGH THE WEEK. FROM THURSDAY ON THROUGH SATURDAY 850MB TEMPS WILL BE +5-10C. THIS SHOULD ALLOW DAYTIME MAX TEMPS TO EASILY REACH THE 50S AND EVEN LOWER 60S EAST OF THE BLUE RIDGE BY THE END OF THE WEEK. WHILE WE WILL BE WARMER...A STRONG COLD FRONT WILL BEGIN TO APPROACH THE REGION ON THURSDAY AND FRIDAY. BOTH THE GFS AND ECMWF BRING MOISTURE IN AHEAD OF THE FRONT. CHANCE SHOWERS ARE MENTIONED FROM THURSDAY THROUGH THE REST OF THE LONG TERM PERIOD ON 12Z SATURDAY. LOOKING BEYOND SATURDAY...A DEEP TROUGH ACROSS THE WESTERN UNITED STATES WILL BRING PLENTY OF COLD AIR FROM CANADA ALL THE WAY INTO THE CENTRAL PLAINS. BY THE END OF THE 240HR MODEL RUN OUR REGION CONTINUES TO BE UNDER THE INFLUENCE OF THE RIDGE AND THUS WILL STAY ON THE WARMER SIDE. A CLOSER EYE WILL BE PAID TO FUTURE MODEL RUNS TO SEE HOW THE PATTERN PROGRESSES. && .AVIATION /05Z SATURDAY THROUGH WEDNESDAY/... AS OF 1210 AM EST SATURDAY... VFR CONDITIONS EXPECTED DURING MUCH OF THIS PERIOD. PREVIOUS FORECASTS WERE THINKING SOME MVFR CIGS AT BLF/LWB/BCB. 00Z SOUNDING AT RNK...FORECAST MODEL SOUNDINGS AND SATELLITE SHOW NO INDICATION THAT LOWER CIGS WILL BE DEVELOP DUE TO DRY AIR. WILL GO WITH SCT020 AROUND 09Z...BUT CONFIDENCE IS HIGH THAT MVFR CIGS WILL NOT FORM. HIGH PRESSURE WEDGED SOUTHWARD ACROSS THE MID ATLANTIC INTO THE CAROLINAS WITH TIGHER GRADIENT OVER THE MTNS WILL LEAD TO SOME GUSTS TO 20-25 KNOTS AT BLF EARLY BEFORE RELAXING. MVFR CIGS ARE POSSIBLE SATURDAY AFTERNOON AND EVENING IN THE PIEDMONT AS LOW LEVEL WINDS VEER MORE EASTERLY AND WE START TO TAP ATLANTIC MOISTURE INTO THE REGION. BY LATE SATURDAY NIGHT LOW LEVEL WINDS ARE EXPECTED TO HAVE VEERED SOUTHWEST...AND WE LOSE THE UPLSOPE COMPONENT RESPONSIBLE FOR THE MVFR CLOUDS. WITH CONFIDENCE IN THIS REMAINING LOW WILL ONLY HAVE FEW-SCT MVFR AT DAN/LYH. SUNDAY INTO MONDAY MAINLY VFR CONDITIONS ARE EXPECTED AS WE BECOME POSITIONED BETWEEN A LOW MOVING NORTH ALONG THE COAST AND A TROUGH AXIS OVER THE OH/TN VALLEY. ISOLATED TO SCATTERED RAIN/SNOW SHOWERS WILL BE POSSIBLE BY MONDAY NIGHT AS THE TROUGH APPROACHES FROM THE WEST. TUESDAY INTO WEDNESDAY MAINLY VFR CONDITIONS ARE EXPECTED AS THE TROUGH PASSES TO OUR EAST AND AN AREA OF LOW PRESSURE DEVELOPS OFF THE COAST. OUR REGION WILL BE LEFT IN A NORTHWEST FLOW PATTERN WITH THE POTENTIAL FOR UPSLOPE CLOUDS OVER THE MOUNTAINS. THERE MAY BE PATCHY MVFR CIGS WITHIN THESE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...DS NEAR TERM...DS/PC SHORT TERM...WERT LONG TERM...CF AVIATION...DS/PC/WP
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
925 AM EST SAT NOV 30 2013 .DISCUSSION... CURRENT-THIS AFTERNOON...FIRST COUPLE OF VISIBLE SATELLITE IMAGES SHOWING CLOUD COVER THINNING OUT TO THE EAST OF THE COAST FROM VERO BEACH NORTH. SKIES EAST OF THE COAST FROM FORT PIERCE SOUTH WERE CLOUDY AND RADAR SHOWED HEAVIER RAIN ASSOCIATED WITH A LINE OF WIND CONVERGENCE THAT STRETCHED PAST GRAND BAHAMA. ANOTHER AREA OF HEAVIER RAIN WAS APPROACHING THE BREVARD VOLUSIA COUNTY COAST BETWEEN CAPE CANAVERAL AND PONCE INLET. THIS AREA OF RAIN SHOULD BE SHORT LIVED AS THE VERTICAL WIND PROFILER(S) AT THE SPACE CENTER WERE DETECTING EASTERLY WINDS 15 TO 20 MPH PUSHING THE RAIN TOWARD THE COAST. MORNING UPDATE WILL LOOK AT POTENTIAL CHANGES TO SKY COVER. WINDS LOOK GOOD BASED ON THE VERTICAL WIND PROFILER OBSERVATIONS. PREVIOUS ZONES DISCUSSION TODAY...HIGH PRESSURE CENTERED OVER NEW ENGLAND WILL SHIFT EAST WHILE ITS RIDGE AXIS EXTENDS SOUTHWARD ALONG THE EASTERN SLOPES OF THE APPALACHIANS. THIS SLIGHT SHIFT IN ORIENTATION OF THE HIGH SHOULD ALLOW THE INVERTED COASTAL TROUGH JUST OFFSHORE THE FL EAST COAST TO BREAK DOWN...CAUSING WINDS TO VEER FROM NORTH TO NORTHEAST BUT REMAINING BREEZY. IT WILL ALSO BRING SHOWERS ACROSS THE COAST AND HAVE INCREASED RAIN CHANCES TO 30 PERCENT ALONG THE COAST...20 PERCENT INTERIOR...WHICH IS A LITTLE ABOVE MOS GUIDANCE. WOULD NOT BE SURPRISED IF THE FOCUS FOR SHOWERS IS THIS MORNING WITH SOME DECREASE IN RAIN CHANCES THIS AFTN. THUNDER IS NOT EXPECTED. MAX TEMPS WILL REACH THE MID TO UPPER 70S WHICH IS A FEW DEGREES ABOVE NORMAL. TONIGHT...WIND FLOW IS FORECAST TO VEER A LITTLE MORE TO THE ENE. AS A RESULT...THE GFS PULLS SOME HIGHER MOISTURE TOWARD THE COAST ASSOCD WITH AN OLD FRONTAL BOUNDARY. SO WILL HOLD ONTO SLIGHT CHANCE (20 PERCENT) POPS FOR THE COAST. SFC WINDS OVER THE INTERIOR WILL BECOME LIGHT NORTH WHICH MAY PRODUCE SOME LOW CLOUDS/PATCHY FOG OVER THE FAR INTERIOR. SUN/MON...MID LEVEL FLOW WILL BRIEFLY BECOME ZONAL EARLY SUNDAY BEFORE BACKING SUNDAY NIGHT AND EARLY MONDAY IN RESPONSE TO TAIL END OF QUICK MOVING SHORTWAVE WHICH WILL PASS OFFSHORE BY SUNSET MONDAY. SHALLOW/MOIST ONSHORE FLOW WILL ADVECT SMALL COVERAGE OF SHOWERS ONSHORE SUNDAY THROUGH EARLY MONDAY...MAINLY IMPACTING COASTAL COUNTIES. SURFACE CONVERGENCE ASSOCIATED WITH WEAK FRONT WILL PROLONG ISOLATED SHOWERS CHANCE INTO MONDAY...EVEN INLAND. NW WIND SHIFT BY LATE AFTERNOON/EVENING WILL RETURN DRIER AIRMASS. TEMPS SEVERAL DEGREES ABOVE NORMAL...ESPECIALLY MINS NEAR THE COAST. TUE-FRI...ZONAL MID LEVEL FLOW TUE BECOMES INCREASINGLY ANTICYCLONIC MID-LATE WEEK WITH 500 MB HEIGHTS RISING 12+ DM AS A RIDGE BUILDS FROM THE YUCATAN PENINSULA TO SOUTH FLORIDA TO NEAR BERMUDA. MEANWHILE...SURFACE HIGH SINKS SLOWLY SE FROM NEAR THE CAROLINA COAST TO THE WESTERN ATLANTIC WITH THE RIDGE AXIS DROPPING TO NORTH FLORIDA BY LATE WEDNESDAY...THEN SETTLING TO THE CENTRAL/SOUTH PENINSULA THU/FRI. GENERALLY LIGHT FLOW VEERS TO EASTERLY WED/THU AND SE FRI...TAPPING 1000-500 MB RELATIVE HUMIDITY VALUES IN THE 40-45 PERCENT RANGE. FORECAST WILL THEREFORE REMAIN DRY DURING THE EXTENDED PERIOD...WITH THE NEXT THREAT OF SHOWER LIKELY HOLDING OFF TIL NEXT FRONT POSSIBLY APPROACHES NEXT WEEKEND. TEMPS FALL TO NEAR CLIMO TUE IN WAKE OF FRONTAL BOUNDARY/WIND SHIFT...THEN WILL REBOUND NEAR TWO DEGREE PER DAY WED-FRI AS ONSHORE/VEERING FLOW SLOWLY MODIFIES AIRMASS. && .AVIATION... IFR CEILINGS OVER THE INTERIOR WEST OF KMCO BECOME MVFR/VFR AFTER 15Z AS THE MODERATE TO FRESH EASTERLY FLOW COMING IN FROM THE EAST PUSHES THE LOW CLOUDS OUT OF THE AREA. TEMPO MVFR CEILINGS AND VISIBILITIES ALONG THE COAST AS SHOWERS COME OFF THE ATLANTIC AND MOVE INLAND. LOOKING AT PREVAILING MVFR/VFR AFTER 15Z NORTH OF KFPR AS VISIBLE SATELLITE IMAGES SHOW THE CLOUD COVER BECOMING SCATTERED. PREVIOUS AVIATION DISCUSSION OCCASIONAL CIGS NEAR 010 AGL WILL OCCUR AT MCO/SFB/DAB THROUGH 12Z BUT THEN SHOULD DIMINISH AS WINDS VEER FROM NORTH TO NE. EXPECT A HIGHER STRATOCUMULUS CEILING TO AFFECT MUCH OF THE COAST THROUGH 00Z WITH BASES MAINLY AT OR ABOVE 035 AGL. THERE IS A CHANCE FOR TEMPO MVFR CONDS AS ISOLATED TO SCATTERED SHOWERS PUSH INTO THE COAST. SOME OF THE STRATOCUMULUS WILL PUSH TO THE INTERIOR TERMINALS. && .MARINE... CURRENT-THIS AFTERNOON...REPORTS FROM BUOY 009 20NM EAST OF CAPE CANAVERAL HAS SHOWN STEADY EASTERLY WINDS IN THE 20 TO 25 KNOT RANGE WITH A SHARP INCREASE FROM 7 FEET TO 8 AND 9 PLUS FEET THE PAST COUPLE OF HOURS DUE TO THE STRONGER WINDS BUILDING THE SEAS. THE SCRIPPS BUOY 4NM EAST OF PORT CANAVERAL WAS RECORDING 5 FOOT SEAS AND THE BUOY 6NM NORTHEAST OF FORT PIERCE INLET WAS RECORDING 7 FOOT SEAS. THE LATEST RUC AND MSAS SURFACE ANALYSIS INDICATE THAT THE SURFACE TROUGH EAST OF FLORIDA WAS SLOW TO BREAK DOWN. WINDS/SEAS MAY BE A BIT LOW BUT WILL WATCH THE BUOY REPORTS FOR ANOTHER HOUR BEFORE MAKING ANY SIGNIFICANT CHANGES TO THE AFTERNOON FORECAST. PREVIOUS MARINE DISCUSSION TODAY/TONIGHT...BOATING CONDITIONS WILL REMAIN POOR FOR SMALL CRAFT ESPECIALLY IN THE GULF STREAM. COASTAL TROUGH WILL BREAK DOWN AND WINDS SHOULD BECOME UNIFORMLY NE ACROSS THE WATERS. PRESSURE GRADIENT WILL SUPPORT 15-20 KNOTS WITH SEAS 5 TO 7 FEET...AND A LITTLE HIGHER IN THE GULF STREAM. SO WILL MAINTAIN SMALL CRAFT ADVISORY FOR ALL THE WATERS TODAY. WINDS SHOULD BEGIN TO DECREASE A BIT TONIGHT AS PRES GRAD SLACKENS SUPPORTING AROUND 15 KNOTS. SHOULD BE ABLE TO TRANSITION TO ADVISORY FOR THE GULF STREAM ONLY WITH A CAUTION FOR THE NEARSHORE WATERS TONIGHT. SUN-WED...NE/E FLOW LESSENS BELOW 15 KT BUT LONG ONSHORE FETCH MEANS SEAS WILL BE SLOW TO SUBSIDE. WILL EXTEND SCA FOR SEAS WITHIN THE GULF STREAM THROUGH THE AFTERNOON. BRIEF INCREASE OF NW FLOW BEHIND FRONT MONDAY WILL BUMP WINDS TO NEAR 15 KT AND SUSTAIN SEAS 5-6 FEET WITHIN GULF STREAM...AND 3-4 FT NEAR SHORE THROUGH DAYBREAK TUE. WIND/SEA CONDITIONS IMPROVE SIGNIFICANTLY BY WED AS LOW LEVEL RIDGE AXIS BUILDS DOWN THE ATLANTIC SEABOARD. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR COASTAL WATERS FROM FLAGLER BEACH TO SEBASTIAN INLET OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 4 PM EST SUNDAY FOR COASTAL WATERS FROM SEBASTIAN INLET TO JUPITER INLET OUT 20 NM-WATERS FROM FLAGLER BEACH TO JUPITER INLET 20 TO 60 NM OFFSHORE. && $$ UPDATES.....WIMMER IMPACT WX...PENDERGRAST
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
954 AM EST SAT NOV 30 2013 .UPDATE... NEAR TERM FOR THE REST OF TODAY HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 328 AM EST SAT NOV 30 2013 AFTER A MAINLY SUNNY DAY...CLOUDS WILL INCREASE ACROSS THE OHIO VALLEY FOR THE SECOND HALF OF THE WEEKEND INTO EARLY NEXT WEEK AS A WEAK FRONT SLIDES INTO THE REGION. A FEW LIGHT RAIN SHOWERS OR SPRINKLES WILL BE POSSIBLE FROM SUNDAY AFTERNOON THROUGH MONDAY AS A COUPLE OF WEAK WAVE ALOFT MOVE ACROSS THE OHIO VALLEY. A MUCH BETTER CHANCE FOR RAIN WILL COME FOR THE SECOND HALF OF THE WEEK AS A STRONG COLD FRONT TRACKS THROUGH THE REGION. COLDER AIR WILL ONCE AGAIN RETURN BY THE END OF THE WEEK. && .NEAR TERM /REST OF TODAY/... ISSUED AT 954 AM EST SAT NOV 30 2013 UPDATE... SOME MID/HIGH CLOUDS WERE STILL ACROSS OUR FAR EAST...BUT HAVE CLEARED OUT ELSEWHERE. UPSTREAM SKIES WERE CLEAR AND WILL SCALE BACK CLOUD COVER A LITTLE WITH MOST AREAS BEING SUNNY THIS AFTERNOON. ONLY OTHER CHANGE WAS TO TWEAK TEMPERATURES UP A DEGREE SOME AREAS BASED ON 12Z RUC 2 METER TEMPERATURES...LOTS OF SUNSHINE AND WARM ADVECTION. ALL IN ALL THE CURRENT FORECAST IS ON TRACK. PREVIOUS NEAR TERM DISCUSSION FOLLOWS... MID AND HIGH LEVEL CLOUD COVER DRAPED ACROSS MUCH OF THE OHIO VALLEY EARLY THIS MORNING AS A WEAK WAVE ALOFT TRACKS ACROSS THE AREA. TEMPS WERE MAINLY IN THE 20S AT 08Z. BACK EDGE OF THE MORE SUBSTANTIAL HIGHER CLOUDS IS ALREADY EAST OF THE MISSISSIPPI RIVER EARLY THIS MORNING. EXPECT CLOUDS TO DIMINISH FROM WEST TO EAST ACROSS THE FORECAST AREA AROUND OR SHORTLY AFTER DAYBREAK...WITH SKIES THEN BECOMING MOSTLY SUNNY WITH ONLY PATCHY CIRRUS FOR THE REST OF THE DAY. WITH THE BROAD HIGH PRESSURE RIDGE NOW LOCATED EAST OF THE REGION...RETURN SOUTHERLY FLOW WILL DEVELOP AND INCREASE BY THIS AFTERNOON AS BOUNDARY LAYER FLOW STRENGTHENS AHEAD OF AN APPROACHING COLD FRONT. MODEL SOUNDINGS SUPPORT MAX GUSTS TO 20-25MPH BY THE AFTERNOON AS LOW LEVEL MIXING INCREASES. GUSTS WILL DROP OFF NEAR SUNSET AS THE NOCTURNAL INVERSION ESTABLISHES. TEMPS...SOUTHERLY FLOW AND WARM ADVECTION WILL BRING WARMER TEMPS INTO CENTRAL INDIANA FOR TODAY. MOS GUIDANCE MATCHES UP NICELY WITH LOW LEVEL THERMALS...WITH HIGHS TOPPING OUT NEAR LATE NOVEMBER NORMALS IN THE MID/UPPER 40S. && .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... ISSUED AT 328 AM EST SAT NOV 30 2013 FORECAST CHALLENGES FOCUS ON POTENTIAL FOR LIGHT PRECIP AS THE AFOREMENTIONED COLD FRONT DROPS INTO THE REGION...STALLS AND EVENTUALLY WASHES OUT. PREDOMINANT ZONAL FLOW IN THE UPPER LEVELS WILL BE PRESENT THROUGH THE PERIOD WITH SEVERAL WEAK WAVES ALOFT TRACKING QUICKLY THROUGH THE OHIO VALLEY. AT THE SURFACE...THE COLD FRONT WILL SLIDE SLOWLY SOUTH INTO THE REGION ON SUNDAY...EVENTUALLY STALLING OUT OVER SOUTHERN INDIANA SUNDAY NIGHT BEFORE WASHING OUT MONDAY. MOISTURE ACCOMPANYING THE FRONT WILL BE LIMITED...BUT MODEL SOUNDINGS AND RH PROGS CONTINUE TO SHOW IT IN GREATEST ABUNDANCE IN THE UPPER PORTIONS OF THE BOUNDARY LAYER BEGINNING EARLY SUNDAY...GRADUALLY LOWERING TO AROUND 2-3KFT INTO MONDAY AS AN INVERSION STEADILY STRENGTHENS. EXPECT CLOUDS TO EXPAND SOUTHEAST INTO THE FORECAST AREA AHEAD OF THE FRONT BEGINNING LATE TONIGHT AND CONTINUING INTO SUNDAY. WEAK ISENTROPIC LIFT AND A SUBTLE WAVE ALOFT MAY BE JUST ENOUGH TO GENERATE SOME LIGHT PRECIP SUNDAY AFTERNOON AND NIGHT...LIKELY IN THE FORM OF SPRINKLES...DRIZZLE OR VERY LIGHT RAIN SHOWERS. LOW LEVELS AND SURFACE TEMPS SHOULD REMAIN WARM ENOUGH TO SUPPORT PRECIP TYPE AS RAIN ONLY SUNDAY NIGHT. MODEL GUIDANCE LARGELY IN AGREEMENT ON BRINGING A SLIGHTLY STRONGER...BETTER PHASED UPPER WAVE ACROSS THE OHIO VALLEY ON MONDAY. WITH LOW LEVEL MOISTURE IN ABUNDANCE... THIS FEATURE SHOULD PRESENT A BETTER OPPORTUNITY FOR A FEW LIGHT RAIN SHOWERS. WILL CARRY JUST LOW CHANCE POPS HOWEVER AS ISENTROPIC LIFT REMAINS WEAK. MAJORITY OF THE MODEL GUIDANCE FAVORING THE PASSAGE OF THIS UPPER WAVE BY MONDAY EVENING...AND WILL END PRECIP CHANCES AS RIDGING ALOFT EXPANDS INTO THE OHIO VALLEY BY EARLY TUESDAY. TEMPS...CONSIDERING THE INCREASING CLOUDS AND POTENTIAL FOR WEAK COLD ADVECTION TO DEVELOP ON SUNDAY...METMOS TEMPS IN THE UPPER 40S/LOWER 50S LOOK RATHER AGGRESSIVE. HAVE TRENDED CLOSER TO /BUT NOT AS COLD AS/ THE MAVMOS FOR SUNDAY HIGHS. LEANED TOWARDS THE MAVMOS AGAIN FOR MONDAY WITH LIGHT RAIN/CLOUDS PRESENT. NEAR MAVMOS FOR LOWS TONIGHT...THEN TRENDED TOWARDS THE WARMER METMOS FOR SUNDAY NIGHT WITH EXPECTED CLOUD COVER. && .LONG TERM /TUESDAY THROUGH FRIDAY/... ISSUED AT 328 AM EST SAT NOV 30 2013 ENSEMBLES ARE IN GOOD AGREEMENT ON THE EVOLVING WEATHER PATTERN NEXT WEEK. UPPER RIDGING EXPECTED TO DEVELOP ALONG THE EAST COAST AS A TROUGH SETS UP FROM THE NORTHERN MIDWEST BACK INTO THE SOUTHERN ROCKIES. THIS WILL RESULT IN SOUTHWESTERLY UPPER FLOW LOCALLY. APPEARS A DECENT CHUNK OF ENERGY WILL EJECT OUT OF THE WESTERN TROUGH INTO WESTERN GREAT LAKES AROUND NEXT THURSDAY. WILL KEEP POPS IN THE FORECAST FOR RAIN ON WEDNESDAY AND ESPECIALLY THURSDAY AS THE UPPER DISTURBANCE MOVES THROUGH. SEVERAL ENSEMBLES SUGGEST MORE ENERGY MAY EJECT OUT ACROSS THE OHIO OR TENNESSEE VALLEY AROUND NEXT FRIDAY...WHICH MAY INDUCE A SURFACE WAVE ON THE PRIMARY COLD FRONT. WILL GO WITH CHANCE POPS FOR RAIN OR SNOW AT THAT TIME. AT THIS POINT...THE ENSEMBLES INDICATE ANY SNOW ACCUMULATIONS LATE NEXT WEEK WILL BE MINOR. && .AVIATION /DISCUSSION FOR THE 301500Z TAF UPDATE/... ISSUED AT 920 AM EST SAT NOV 30 2013 KIND TAF LOOKS GOOD. ONLY MINOR TWEAKS MADE. PREVIOUS DISCUSSION FOLLOWS... NO SIGNIFICANT CLOUD COVER...UNRESTRICTED VISIBILITY...SURFACE WINDS AT OR BELOW 10 KTS EXPECTED AT THE TAF SITES THROUGH 010000Z. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN/JH SHORT TERM...RYAN LONG TERM....JAS AVIATION...JAS/50 VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1051 AM EST SAT NOV 30 2013 .SYNOPSIS... HIGH PRESSURE WILL EXTEND SOUTHWEST INTO THE REGION THROUGH TONIGHT...THEN WEAKEN ON SUNDAY. A LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP ALONG THE CAROLINA COAST ON MONDAY AS AN UPPER LEVEL DISTURBANCE APPROACHES FROM THE WEST. && .NEAR TERM /THROUGH TODAY/... AS OF 1050 AM SATURDAY... SURFACE HIGH AS OF 15Z IS CENTERED WELL TO THE NORTHEAST...OVER NEW ENGLAND AND INTO MAINE...WITH THE RIDGE AXIS EXTENDING SOUTHWEST INTO NC...MAINLY ALONG THE WESTERN PORTION OF THE AREA. THE PRESSURE GRADIENT WILL RELAX SOME AS THE HIGH MOVES OFF THE NE COAST AND THE RIDGE WEAKENS...THUS ALLOWING THE WINDS TO RELAX SOME AS WELL. THE RETURN FLOW WILL BECOME MORE NORTHEASTERLY AS THAT HAPPENS... ALLOWING FOR WARMER TEMPS ACROSS THE SOUTH AND EAST AND COOLER IN THE NW. THE 12Z UPPER AIR ANALYSES SHOW THE TROUGH... MORE PROMINENT AT 700 AND 850 MB...EXTENDING FROM THE WESTERN GREAT LAKES SW INTO OK/TX...WITH HIGH PRESSURE/RIDGING OVER THE EASTERN US. AN UPPER LEVEL WAVE JUST WEST OF THE APPALACHIANS...SHOWN IN BOTH SATELLITE IMAGERY AND INDICATED BY MODEL GENERATED VORTICITY PLOTS...IS GENERATING AN AREA OF CLOUDS OVER WV/VA...WHICH MAY EXTEND INTO THE NORTHERN AND WESTERN PORTIONS OF THE AREA TODAY...ALTHOUGH THE GREATEST COVERAGE WILL BE OVER VA. WITH THE STRONG WESTERLY FLOW ALOFT EXPECTED TO CONTINUE TODAY AS THE UPPER LEVEL RIDGE CONTINUES TO BUILD...SUBSIDENCE SHOULD BE STRONG ENOUGH TO LIMIT MIXING IN THE LOW LEVELS...WHICH IN COMBINATION WITH THE INCREASING CLOUD COVER... SHOULD BE ENOUGH TO YIELD HIGHS TODAY A BIT COOLER THAN YESTERDAY... MAINLY IN THE MID 40S TO LOW 50S. -KC THE LATEST RAP...ALONG WITH THE HRRR WRF...FORECAST AN INCREASE IN LOW-LEVEL MOISTURE FROM THE SOUTHEAST LATE IN THE DAY. THIS MAY BE REASONABLE...AS THE SATELLITE FOG PRODUCT SHOWED AREAS OF LOW CLOUDS JUST OFFSHORE FROM SOUTHEAST NORTH CAROLINA EARLY THIS MORNING. HAVE ADDED SOME CLOUD COVER TO THE FORECAST PARTICULARLY TOWARD THE SOUTH AND EAST DURING THE AFTERNOON. -DJF && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... AS OF 650 AM SATURDAY... SURFACE HIGH PRESSURE SHOULD BE DIRECTLY OVERHEAD OVERNIGHT KEEPING THE GRADIENT VERY RELAXED. THE POTENTIAL FOR A QUITE CHILLY NIGHT WOULD EXIST BUT THE COMBINATION OF SOME HIGH CLOUDS AND THE GFS FORECAST OF INCREASING 850MB MOISTURE FROM THE SOUTH AND SOUTHWEST MAY ACT TO KEEP TEMPERATURES CLOSE TO THE GUIDANCE LOWS OVERNIGHT. THE LATEST SATELLITE FOG PRODUCT SHOWS LOW-LEVEL MOISTURE MOVING WEST TOWARD THE SOUTH CAROLINA COAST...AND LOW-LEVEL ISENTROPIC FORECASTS ALONG WITH THE INCREASING 850MB MOISTURE SUPPORT AN INCREASE IN CLOUD COVER TO PARTLY-TO-MOSTLY CLOUDY PARTICULARLY ALONG AND SOUTH OF ABOUT INTERSTATE 85 DURING THE OVERNIGHT HOURS. THE TIMING OF THIS IS...OF COURSE...CRITICAL TO THE OVERNIGHT TEMPERATURE FORECAST...BUT FOR THIS FORECAST WILL LEAN TOWARD THE COOLER MOS GUIDANCE IN THE TRIAD AND THE WARMER MOS GUIDANCE ELSEWHERE. K INDICES SLOWLY RISE SUNDAY...WITH PRECIPITABLE WATER VALUES RISING LATE SUNDAY TO BETWEEN 0.75 AND ONE INCH...ABOVE NORMAL FOR VERY EARLY DECEMBER AT ABOUT THE 75TH PERCENTILE. LIFT STARTS TO INCREASE LATE SUNDAY AND PARTICULARLY SUNDAY NIGHT AS ISENTROPIC LIFT ON THE 300K SURFACE INCREASES...WITH THE BEST POTENTIAL VORTICITY ON THE 1.5PVU SURFACE FORECAST BY THE GFS ALONG AND SOUTH OF ABOUT U.S. 64 LATE SUNDAY THROUGH SUNDAY NIGHT. SURFACE DEPICTIONS OF THE NAM AND GFS DIFFER AND ARE FAIRLY CONSISTENT WITH THEMSELVES OVER THE LAST TWO OR THREE RUNS...WITH THE NAM SHOWING A WEAK SURFACE LOW JUST OFF THE SOUTH CAROLINA COAST SUNDAY NIGHT WHILE THE GFS FORECASTS MORE OF AN INVERTED TROUGH BEFORE SURFACE LOW PRESSURE STRENGTHENS OFFSHORE. REGARDLESS...QPF AND MOS GUIDANCE POPS ARE SIMILAR... KEEPING MOST CHANCES FOR PRECIPITATION AT BAY SUNDAY AND INCREASING CHANCES OVER MOST OF CENTRAL NORTH CAROLINA SUNDAY NIGHT. WILL NOTE A SLIGHT CHANCE OF RAIN MAINLY OVER THE SANDHILLS AND SOUTHERN COASTAL PLAIN SUNDAY WHERE THE BEST LOW-LEVEL MOISTURE SHOULD RESIDE AS POTENTIAL VORTICITY INCREASES...WITH A CHANCE OF RAIN SUNDAY NIGHT MAINLY ALONG AND EAST OF A LINE FROM ABOUT KIXA TO KAFP WITH A SLIGHT CHANCE NORTH OF THAT LINE. DEBATED WHETHER OR NOT TO INCLUDE A SLIGHT CHANCE IN THE TRIAD AND FOR THIS FORECAST WILL SHOW A VERY LOW SLIGHT CHANCE THERE OVERNIGHT SUNDAY...THOUGH THIS COULD END UP BEING OVERDONE WITH SUFFICIENT MOISTURE AND LIFT REMAINING JUST EAST. SURFACE WET BULB TEMPERATURES AND PARTIAL THICKNESSES SUPPORT ALL LIQUID. ONCE AGAIN 1000-850MB THICKNESSES WOULD SUPPORT HIGHS SUNDAY ABOVE MOS GUIDANCE...BUT GIVEN THE EXPECTED CLOUD COVER...WILL FORECAST HIGHS AS A BLEND OF MAV AND MET MOS GUIDANCE FOR A FAIRLY UNIFORM LOWER 50S IN MOST LOCATIONS. OVERNIGHT SUNDAY...IF IT REMAINS DRY IN THE TRIAD LOWS SHOULD BE NEAR THE WARMER GUIDANCE...WHILE WHERE IT RAINS TEMPERATURES WOULD APPROACH THE DEW POINT. THIS COINCIDES WITH A BLEND OF MOS GUIDANCE...ALTHOUGH HIGHER THAN GUIDANCE TOWARD KRWI...FOR LOWS IN THE MID TO UPPER 30S NORTHWEST...TO MID 40S TOWARD KCTZ. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 235 AM SATURDAY... ON MONDAY A LOW AMPLITUDE NORTHERN STREAM SHORTWAVE DROPS INTO THE THE DEEP SOUTH AS A SHEARING SOUTHERN STREAM SYSTEM WITH A 250MB JET OF 140 KTS PHASE TOGETHER BEFORE THE TROUGH AXIS MOVES OFF THE SOUTHEAST COAST MONDAY NIGHT. THE TROUGH BECOMES NEGATIVELY TILTED AND INITIATES SURFACE CYCLOGENESIS MONDAY NIGHT AND TUESDAY. RECENT NWP TRENDS HAVE SUGGESTED A LESS AMPLIFIED SYSTEM WHILE PRODUCING A BIT MORE QPF ACROSS MAINLY SOUTHEASTERN NC. IT REMAINS DIFFICULT AND CONFIDENCE IS LOW REGARDING HOW FAR NORTH AND WEST PRECIPITATION WILL SPREAD ACROSS CENTRAL NC BUT CONFIDENCE IS GROWING THAT SOME LIGHT PRECIPITATION WILL FALL ACROSS THE SOUTHERN COASTAL PLAIN AND SANDHILLS REGION. NWP CONSENSUS SHOWS THE DEEPEST MOISTURE AND STRONGEST FORCING WILL BE CONFINED TO SOUTHEASTERN PORTIONS OF THE RAH CWA WITH RAPIDLY DECREASING RAIN CHANCES ACROSS THE NORTHERN AND WESTERN PIEDMONT. ISENTROPIC ANALYSIS DEPICTS THE PATTERN WELL WITH A FAIRLY NARROW CORRIDOR OF LIFT/SATURATION THAT SLIDES MAINLY ACROSS SOUTHERN AND EASTERN NC. PRECIPITATION CHANCES QUICKLY TAIL OFF FROM WEST TO EAST ON MONDAY NIGHT. THE AIR MASS AHEAD OF THE SYSTEM WILL HAVE MODIFIED AND THE PRECIPITATION WILL FALL AS RAIN. GIVEN THE MODIFICATION OF THE AIR MASS AND THE LIGHT PRECIPITATION CHANCES...DO NOT EXPECT A SIGNIFICANT CAD EVENT TO OCCUR. HIGHS MONDAY WILL RANGE IN THE 49-56 RANGE WITH MAX TEMPERATURES DEPENDENT ON THE LOCATION AND INTENSITY OF THE PRECIPITATION. AFTER THE UPPER TROUGH AXIS MOVES OFFSHORE...THE FLOW ALOFT BECOMES MORE NORTHWESTERLY. ANOTHER DISTURBANCE IN THE FLOW AND SOME RESIDUAL MOISTURE SHOULD BE SUFFICIENT TO PRODUCE SOME CLOUDINESS ON TUESDAY BUT OTHERWISE FAIR CONDITIONS ARE EXPECTED WITH HIGHS IN THE LOWER TO MID 50S. THE FLOW FLATTENS ON TUESDAY NIGHT AND HEIGHTS RISE ON WEDNESDAY INTO THURSDAY WITH INCREASING HIGH CLOUDS LATE WEDNESDAY AND A FAIR AMOUNT OF CLOUDS EXPECTED ON THURSDAY. EXPECT DRY WEATHER THROUGH AT LEAST THURSDAY AFTERNOON AS THE RIDGE AXIS BUILDS OVERHEAD. MODERATING TEMPERATURES ARE EXPECTED ON THURSDAY INTO FRIDAY WITH HIGHS IN THE MID TO UPPER 50S ON WEDNESDAY WARMING INTO THE UPPER 50S TO LOWER 60S ON THURSDAY WITH MORNING LOWS IN THE MID 30S TO AROUND 40. A LONGWAVE TROUGH DEVELOPS OVER THE WESTERN U.S. LATE THURSDAY INTO FRIDAY AS AN ARCTIC AIRMASS DROPS INTO THE NORTHERN ROCKIES AND NORTHERN PLAINS. AN INCREASINGLY MOIST SOUTHERLY TO SOUTHWESTERLY FLOW DEVELOPS ACROSS THE CENTRAL U.S. AS THE TROUGH PUSHES EAST ON FRIDAY. THE ASSOCIATED COLD FRONT REACHES THE WESTERN APPALACHIANS ON FRIDAY MORNING. THERE ARE TIMING DIFFERENCES AMONG THE GUIDANCE REGARDING THE EASTWARD ADVANCEMENT OF THE FRONT AND THE ASSOCIATED PRECIPITATION WITH WPC PREFERRING A GEFS MEAN AND EC ENS MEAN. REGARDLESS...THE THREAT OF RAIN WILL ARRIVE WITH LOW PROBABILITIES IN THE WEST LATE THURSDAY NIGHT. POPS WILL INCREASE FROM WEST TO EAST FRIDAY AND FRIDAY NIGHT WITH THE BEST CHANCE OF RAIN AT THIS POINT APPEARING TO BE FRIDAY NIGHT AND SATURDAY. AHEAD OF THE FRONT AND THE RAIN...TEMPERATURES ARE LIKELY TO CLIMB INTO THE 60S FRIDAY AFTERNOON. -BLAES && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 650 AM SATURDAY... VFR CONDITIONS CONTINUE THROUGH MUCH OF THE 12Z VALID TAF PERIOD. WINDS REMAIN NOTICEABLE DURING THE EARLY MORNING IN THE TIGHTER GRADIENT ON THE EAST SIDE OF THE RIDGE AXIS...AND THE KRAX WSR-88D SHOWED WINDS OF 40KT EARLIER JUST ABOVE 2K FEET...BUT THESE WINDS HAVE SINCE DIMINISHED ALMOST IN HALF SINCE 06Z. MODEL GUIDANCE SHOWS SUCH WINDS CONTINUING TO DECREASE SOME DURING THE MORNING...BUT THESE COULD TRANSLATE TO A FEW WIND GUSTS IN THE TEENS KTS AFTER SUNRISE WITH EVEN MINIMAL MIXING AT KRDU AND ESPECIALLY KFAY AND KRWI. AS HIGH PRESSURE SETTLES OVERHEAD FOR THIS EVENING...WINDS SHOULD BECOME LIGHT. AS LOW-LEVEL MOISTURE INCREASES THIS EVENING AND OVERNIGHT...THERE IS THE POTENTIAL FOR AT LEAST A PERIOD OF MVFR CEILINGS PARTICULARLY TOWARD KFAY WITH A LESSER LIKELIHOOD TOWARD KRDU AND KRWI. BEYOND THE 12Z VALID TAF PERIOD...SUB-VFR CONDITIONS ARE POSSIBLE EARLY SUNDAY MAINLY TOWARD KFAY...AND SUCH CONDITIONS ARE QUITE POSSIBLE SUNDAY NIGHT MAINLY EAST AND SOUTHEAST OF THE TRIAD AS MOISTURE INCREASES...ALONG WITH A CHANCE OF RAIN MAINLY EAST AND SOUTHEAST OF THE TRIAD. THE PROBABILITY OF SUB-VFR CONDITIONS INCREASES LATE SUNDAY NIGHT INTO MONDAY...AGAIN BEST EAST AND SOUTHEAST OF THE TRIAD...WITH IMPROVING CONDITIONS FOR TUESDAY CONTINUING INTO WEDNESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE && $$ SYNOPSIS...VINCENT NEAR TERM...KC/DJF SHORT TERM...DJF LONG TERM...BLAES AVIATION...DJF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
958 AM EST SAT NOV 30 2013 .SYNOPSIS... HIGH PRESSURE WILL EXTEND SOUTHWEST INTO THE REGION THROUGH TONIGHT...THEN WEAKEN ON SUNDAY. A LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP ALONG THE CAROLINA COAST ON MONDAY AS AN UPPER LEVEL DISTURBANCE APPROACHES FROM THE WEST. && .NEAR TERM /THROUGH TODAY/... AS OF 650 AM SATURDAY... THE LATEST SURFACE ANALYSIS SHOWED THE AXIS OF SURFACE HIGH PRESSURE NORTHEAST TO SOUTHWEST ACROSS CENTRAL NORTH CAROLINA...AND DURING THE DAY THE RIDGE SETTLES SLOWLY SOUTH WHICH SHOULD RELAX THE GRADIENT FOR THE LATE DAY AND OVERNIGHT. A MODERATE MID-LEVEL SHORTWAVE WAS OBSERVED ON WATER VAPOR IMAGERY MOVING EAST FROM MISSOURI AND ILLINOIS TOWARD THE MID-ATLANTIC...WITH A MID-LEVEL TROUGH PASSING EAST OF THE STATE AS OF THIS WRITING. 1000-850MB THICKNESSES ARE FORECAST VERY SIMILAR TO THOSE THAT OCCURRED FRIDAY...WHEN HIGHS WERE AROUND 50 TO THE MID 50S. HOWEVER... GUIDANCE IS VERY CONSISTENT IN SHOWING HIGHS TODAY ROUGHLY A CATEGORY...POSSIBLY EVEN TWO...COOLER. NAM AND GFS BUFR SOUNDINGS MAINTAIN STRONG SUBSIDENCE AND LIMITED MIXING POTENTIAL...AND AHEAD OF THE MODEST MID-LEVEL SHORTWAVE TO OUR WEST THAT BOTH THE NAM AND THE GFS MOVE ACROSS CENTRAL NORTH CAROLINA LATE THIS AFTERNOON AND OVERNIGHT...DIFFLUENCE ALOFT INCREASES AS A 90KT 300MB JET APPROACHES FROM THE WEST...WITH POSSIBLY JUST ENOUGH HIGH CLOUDS TO TEMPER HIGHS SOMEWHAT. WILL LEAN TOWARD WARMER GUIDANCE FOR HIGHS IN THE MID 40S TO LOWER 50S. ESPECIALLY ALONG AND EAST OF U.S. 1 THERE SHOULD BE JUST A FEW WIND GUSTS IN THE TEENS KNOTS WITH MIXING LATER THIS MORNING BEFORE THE SURFACE RIDGING SETTLES SOUTH. 925MB WINDS ARE FORECAST ONLY TO AROUND 15KT DURING THE DAY. THE LATEST RAP...ALONG WITH THE HRRR WRF...FORECAST AN INCREASE IN LOW-LEVEL MOISTURE FROM THE SOUTHEAST LATE IN THE DAY. THIS MAY BE REASONABLE...AS THE SATELLITE FOG PRODUCT SHOWED AREAS OF LOW CLOUDS JUST OFFSHORE FROM SOUTHEAST NORTH CAROLINA EARLY THIS MORNING. HAVE ADDED SOME CLOUD COVER TO THE GRIDDED AND WORDED FORECASTS PARTICULARLY TOWARD KCTZ DURING THE AFTERNOON. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... AS OF 650 AM SATURDAY... SURFACE HIGH PRESSURE SHOULD BE DIRECTLY OVERHEAD OVERNIGHT KEEPING THE GRADIENT VERY RELAXED. THE POTENTIAL FOR A QUITE CHILLY NIGHT WOULD EXIST BUT THE COMBINATION OF SOME HIGH CLOUDS AND THE GFS FORECAST OF INCREASING 850MB MOISTURE FROM THE SOUTH AND SOUTHWEST MAY ACT TO KEEP TEMPERATURES CLOSE TO THE GUIDANCE LOWS OVERNIGHT. THE LATEST SATELLITE FOG PRODUCT SHOWS LOW-LEVEL MOISTURE MOVING WEST TOWARD THE SOUTH CAROLINA COAST...AND LOW-LEVEL ISENTROPIC FORECASTS ALONG WITH THE INCREASING 850MB MOISTURE SUPPORT AN INCREASE IN CLOUD COVER TO PARTLY-TO-MOSTLY CLOUDY PARTICULARLY ALONG AND SOUTH OF ABOUT INTERSTATE 85 DURING THE OVERNIGHT HOURS. THE TIMING OF THIS IS...OF COURSE...CRITICAL TO THE OVERNIGHT TEMPERATURE FORECAST...BUT FOR THIS FORECAST WILL LEAN TOWARD THE COOLER MOS GUIDANCE IN THE TRIAD AND THE WARMER MOS GUIDANCE ELSEWHERE. K INDICES SLOWLY RISE SUNDAY...WITH PRECIPITABLE WATER VALUES RISING LATE SUNDAY TO BETWEEN 0.75 AND ONE INCH...ABOVE NORMAL FOR VERY EARLY DECEMBER AT ABOUT THE 75TH PERCENTILE. LIFT STARTS TO INCREASE LATE SUNDAY AND PARTICULARLY SUNDAY NIGHT AS ISENTROPIC LIFT ON THE 300K SURFACE INCREASES...WITH THE BEST POTENTIAL VORTICITY ON THE 1.5PVU SURFACE FORECAST BY THE GFS ALONG AND SOUTH OF ABOUT U.S. 64 LATE SUNDAY THROUGH SUNDAY NIGHT. SURFACE DEPICTIONS OF THE NAM AND GFS DIFFER AND ARE FAIRLY CONSISTENT WITH THEMSELVES OVER THE LAST TWO OR THREE RUNS...WITH THE NAM SHOWING A WEAK SURFACE LOW JUST OFF THE SOUTH CAROLINA COAST SUNDAY NIGHT WHILE THE GFS FORECASTS MORE OF AN INVERTED TROUGH BEFORE SURFACE LOW PRESSURE STRENGTHENS OFFSHORE. REGARDLESS...QPF AND MOS GUIDANCE POPS ARE SIMILAR... KEEPING MOST CHANCES FOR PRECIPITATION AT BAY SUNDAY AND INCREASING CHANCES OVER MOST OF CENTRAL NORTH CAROLINA SUNDAY NIGHT. WILL NOTE A SLIGHT CHANCE OF RAIN MAINLY OVER THE SANDHILLS AND SOUTHERN COASTAL PLAIN SUNDAY WHERE THE BEST LOW-LEVEL MOISTURE SHOULD RESIDE AS POTENTIAL VORTICITY INCREASES...WITH A CHANCE OF RAIN SUNDAY NIGHT MAINLY ALONG AND EAST OF A LINE FROM ABOUT KIXA TO KAFP WITH A SLIGHT CHANCE NORTH OF THAT LINE. DEBATED WHETHER OR NOT TO INCLUDE A SLIGHT CHANCE IN THE TRIAD AND FOR THIS FORECAST WILL SHOW A VERY LOW SLIGHT CHANCE THERE OVERNIGHT SUNDAY...THOUGH THIS COULD END UP BEING OVERDONE WITH SUFFICIENT MOISTURE AND LIFT REMAINING JUST EAST. SURFACE WET BULB TEMPERATURES AND PARTIAL THICKNESSES SUPPORT ALL LIQUID. ONCE AGAIN 1000-850MB THICKNESSES WOULD SUPPORT HIGHS SUNDAY ABOVE MOS GUIDANCE...BUT GIVEN THE EXPECTED CLOUD COVER...WILL FORECAST HIGHS AS A BLEND OF MAV AND MET MOS GUIDANCE FOR A FAIRLY UNIFORM LOWER 50S IN MOST LOCATIONS. OVERNIGHT SUNDAY...IF IT REMAINS DRY IN THE TRIAD LOWS SHOULD BE NEAR THE WARMER GUIDANCE...WHILE WHERE IT RAINS TEMPERATURES WOULD APPROACH THE DEW POINT. THIS COINCIDES WITH A BLEND OF MOS GUIDANCE...ALTHOUGH HIGHER THAN GUIDANCE TOWARD KRWI...FOR LOWS IN THE MID TO UPPER 30S NORTHWEST...TO MID 40S TOWARD KCTZ. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 235 AM SATURDAY... ON MONDAY A LOW AMPLITUDE NORTHERN STREAM SHORTWAVE DROPS INTO THE THE DEEP SOUTH AS A SHEARING SOUTHERN STREAM SYSTEM WITH A 250MB JET OF 140 KTS PHASE TOGETHER BEFORE THE TROUGH AXIS MOVES OFF THE SOUTHEAST COAST MONDAY NIGHT. THE TROUGH BECOMES NEGATIVELY TILTED AND INITIATES SURFACE CYCLOGENESIS MONDAY NIGHT AND TUESDAY. RECENT NWP TRENDS HAVE SUGGESTED A LESS AMPLIFIED SYSTEM WHILE PRODUCING A BIT MORE QPF ACROSS MAINLY SOUTHEASTERN NC. IT REMAINS DIFFICULT AND CONFIDENCE IS LOW REGARDING HOW FAR NORTH AND WEST PRECIPITATION WILL SPREAD ACROSS CENTRAL NC BUT CONFIDENCE IS GROWING THAT SOME LIGHT PRECIPITATION WILL FALL ACROSS THE SOUTHERN COASTAL PLAIN AND SANDHILLS REGION. NWP CONSENSUS SHOWS THE DEEPEST MOISTURE AND STRONGEST FORCING WILL BE CONFINED TO SOUTHEASTERN PORTIONS OF THE RAH CWA WITH RAPIDLY DECREASING RAIN CHANCES ACROSS THE NORTHERN AND WESTERN PIEDMONT. ISENTROPIC ANALYSIS DEPICTS THE PATTERN WELL WITH A FAIRLY NARROW CORRIDOR OF LIFT/SATURATION THAT SLIDES MAINLY ACROSS SOUTHERN AND EASTERN NC. PRECIPITATION CHANCES QUICKLY TAIL OFF FROM WEST TO EAST ON MONDAY NIGHT. THE AIR MASS AHEAD OF THE SYSTEM WILL HAVE MODIFIED AND THE PRECIPITATION WILL FALL AS RAIN. GIVEN THE MODIFICATION OF THE AIR MASS AND THE LIGHT PRECIPITATION CHANCES...DO NOT EXPECT A SIGNIFICANT CAD EVENT TO OCCUR. HIGHS MONDAY WILL RANGE IN THE 49-56 RANGE WITH MAX TEMPERATURES DEPENDENT ON THE LOCATION AND INTENSITY OF THE PRECIPITATION. AFTER THE UPPER TROUGH AXIS MOVES OFFSHORE...THE FLOW ALOFT BECOMES MORE NORTHWESTERLY. ANOTHER DISTURBANCE IN THE FLOW AND SOME RESIDUAL MOISTURE SHOULD BE SUFFICIENT TO PRODUCE SOME CLOUDINESS ON TUESDAY BUT OTHERWISE FAIR CONDITIONS ARE EXPECTED WITH HIGHS IN THE LOWER TO MID 50S. THE FLOW FLATTENS ON TUESDAY NIGHT AND HEIGHTS RISE ON WEDNESDAY INTO THURSDAY WITH INCREASING HIGH CLOUDS LATE WEDNESDAY AND A FAIR AMOUNT OF CLOUDS EXPECTED ON THURSDAY. EXPECT DRY WEATHER THROUGH AT LEAST THURSDAY AFTERNOON AS THE RIDGE AXIS BUILDS OVERHEAD. MODERATING TEMPERATURES ARE EXPECTED ON THURSDAY INTO FRIDAY WITH HIGHS IN THE MID TO UPPER 50S ON WEDNESDAY WARMING INTO THE UPPER 50S TO LOWER 60S ON THURSDAY WITH MORNING LOWS IN THE MID 30S TO AROUND 40. A LONGWAVE TROUGH DEVELOPS OVER THE WESTERN U.S. LATE THURSDAY INTO FRIDAY AS AN ARCTIC AIRMASS DROPS INTO THE NORTHERN ROCKIES AND NORTHERN PLAINS. AN INCREASINGLY MOIST SOUTHERLY TO SOUTHWESTERLY FLOW DEVELOPS ACROSS THE CENTRAL U.S. AS THE TROUGH PUSHES EAST ON FRIDAY. THE ASSOCIATED COLD FRONT REACHES THE WESTERN APPALACHIANS ON FRIDAY MORNING. THERE ARE TIMING DIFFERENCES AMONG THE GUIDANCE REGARDING THE EASTWARD ADVANCEMENT OF THE FRONT AND THE ASSOCIATED PRECIPITATION WITH WPC PREFERRING A GEFS MEAN AND EC ENS MEAN. REGARDLESS...THE THREAT OF RAIN WILL ARRIVE WITH LOW PROBABILITIES IN THE WEST LATE THURSDAY NIGHT. POPS WILL INCREASE FROM WEST TO EAST FRIDAY AND FRIDAY NIGHT WITH THE BEST CHANCE OF RAIN AT THIS POINT APPEARING TO BE FRIDAY NIGHT AND SATURDAY. AHEAD OF THE FRONT AND THE RAIN...TEMPERATURES ARE LIKELY TO CLIMB INTO THE 60S FRIDAY AFTERNOON. -BLAES && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 650 AM SATURDAY... VFR CONDITIONS CONTINUE THROUGH MUCH OF THE 12Z VALID TAF PERIOD. WINDS REMAIN NOTICEABLE DURING THE EARLY MORNING IN THE TIGHTER GRADIENT ON THE EAST SIDE OF THE RIDGE AXIS...AND THE KRAX WSR-88D SHOWED WINDS OF 40KT EARLIER JUST ABOVE 2K FEET...BUT THESE WINDS HAVE SINCE DIMINISHED ALMOST IN HALF SINCE 06Z. MODEL GUIDANCE SHOWS SUCH WINDS CONTINUING TO DECREASE SOME DURING THE MORNING...BUT THESE COULD TRANSLATE TO A FEW WIND GUSTS IN THE TEENS KTS AFTER SUNRISE WITH EVEN MINIMAL MIXING AT KRDU AND ESPECIALLY KFAY AND KRWI. AS HIGH PRESSURE SETTLES OVERHEAD FOR THIS EVENING...WINDS SHOULD BECOME LIGHT. AS LOW-LEVEL MOISTURE INCREASES THIS EVENING AND OVERNIGHT...THERE IS THE POTENTIAL FOR AT LEAST A PERIOD OF MVFR CEILINGS PARTICULARLY TOWARD KFAY WITH A LESSER LIKELIHOOD TOWARD KRDU AND KRWI. BEYOND THE 12Z VALID TAF PERIOD...SUB-VFR CONDITIONS ARE POSSIBLE EARLY SUNDAY MAINLY TOWARD KFAY...AND SUCH CONDITIONS ARE QUITE POSSIBLE SUNDAY NIGHT MAINLY EAST AND SOUTHEAST OF THE TRIAD AS MOISTURE INCREASES...ALONG WITH A CHANCE OF RAIN MAINLY EAST AND SOUTHEAST OF THE TRIAD. THE PROBABILITY OF SUB-VFR CONDITIONS INCREASES LATE SUNDAY NIGHT INTO MONDAY...AGAIN BEST EAST AND SOUTHEAST OF THE TRIAD...WITH IMPROVING CONDITIONS FOR TUESDAY CONTINUING INTO WEDNESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE && $$ SYNOPSIS...VINCENT NEAR TERM...DJF SHORT TERM...DJF LONG TERM...BLAES AVIATION...DJF
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 650 AM
EST SAT NOV 30 2013
.SYNOPSIS... SURFACE HIGH PRESSURE REMAINS IN PLACE THROUGH THE DAY SUNDAY. MOISTURE INCREASES AHEAD OF LOW PRESSURE THAT GRADUALLY STRENGTHENS JUST OFF THE CAROLINA COAST LATE SUNDAY NIGHT THROUGH TUESDAY. HIGH PRESSURE RETURNS FOR THE MIDDLE OF THE WEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 650 AM SATURDAY... THE LATEST SURFACE ANALYSIS SHOWED THE AXIS OF SURFACE HIGH PRESSURE NORTHEAST TO SOUTHWEST ACROSS CENTRAL NORTH CAROLINA...AND DURING THE DAY THE RIDGE SETTLES SLOWLY SOUTH WHICH SHOULD RELAX THE GRADIENT FOR THE LATE DAY AND OVERNIGHT. A MODERATE MID-LEVEL SHORTWAVE WAS OBSERVED ON WATER VAPOR IMAGERY MOVING EAST FROM MISSOURI AND ILLINOIS TOWARD THE MID-ATLANTIC...WITH A MID-LEVEL TROUGH PASSING EAST OF THE STATE AS OF THIS WRITING. 1000-850MB THICKNESSES ARE FORECAST VERY SIMILAR TO THOSE THAT OCCURRED FRIDAY...WHEN HIGHS WERE AROUND 50 TO THE MID 50S. HOWEVER... GUIDANCE IS VERY CONSISTENT IN SHOWING HIGHS TODAY ROUGHLY A CATEGORY...POSSIBLY EVEN TWO...COOLER. NAM AND GFS BUFR SOUNDINGS MAINTAIN STRONG SUBSIDENCE AND LIMITED MIXING POTENTIAL...AND AHEAD OF THE MODEST MID-LEVEL SHORTWAVE TO OUR WEST THAT BOTH THE NAM AND THE GFS MOVE ACROSS CENTRAL NORTH CAROLINA LATE THIS AFTERNOON AND OVERNIGHT...DIFFLUENCE ALOFT INCREASES AS A 90KT 300MB JET APPROACHES FROM THE WEST...WITH POSSIBLY JUST ENOUGH HIGH CLOUDS TO TEMPER HIGHS SOMEWHAT. WILL LEAN TOWARD WARMER GUIDANCE FOR HIGHS IN THE MID 40S TO LOWER 50S. ESPECIALLY ALONG AND EAST OF U.S. 1 THERE SHOULD BE JUST A FEW WIND GUSTS IN THE TEENS KNOTS WITH MIXING LATER THIS MORNING BEFORE THE SURFACE RIDGING SETTLES SOUTH. 925MB WINDS ARE FORECAST ONLY TO AROUND 15KT DURING THE DAY. THE LATEST RAP...ALONG WITH THE HRRR WRF...FORECAST AN INCREASE IN LOW-LEVEL MOISTURE FROM THE SOUTHEAST LATE IN THE DAY. THIS MAY BE REASONABLE...AS THE SATELLITE FOG PRODUCT SHOWED AREAS OF LOW CLOUDS JUST OFFSHORE FROM SOUTHEAST NORTH CAROLINA EARLY THIS MORNING. HAVE ADDED SOME CLOUD COVER TO THE GRIDDED AND WORDED FORECASTS PARTICULARLY TOWARD KCTZ DURING THE AFTERNOON. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... AS OF 650 AM SATURDAY... SURFACE HIGH PRESSURE SHOULD BE DIRECTLY OVERHEAD OVERNIGHT KEEPING THE GRADIENT VERY RELAXED. THE POTENTIAL FOR A QUITE CHILLY NIGHT WOULD EXIST BUT THE COMBINATION OF SOME HIGH CLOUDS AND THE GFS FORECAST OF INCREASING 850MB MOISTURE FROM THE SOUTH AND SOUTHWEST MAY ACT TO KEEP TEMPERATURES CLOSE TO THE GUIDANCE LOWS OVERNIGHT. THE LATEST SATELLITE FOG PRODUCT SHOWS LOW-LEVEL MOISTURE MOVING WEST TOWARD THE SOUTH CAROLINA COAST...AND LOW-LEVEL ISENTROPIC FORECASTS ALONG WITH THE INCREASING 850MB MOISTURE SUPPORT AN INCREASE IN CLOUD COVER TO PARTLY-TO-MOSTLY CLOUDY PARTICULARLY ALONG AND SOUTH OF ABOUT INTERSTATE 85 DURING THE OVERNIGHT HOURS. THE TIMING OF THIS IS...OF COURSE...CRITICAL TO THE OVERNIGHT TEMPERATURE FORECAST...BUT FOR THIS FORECAST WILL LEAN TOWARD THE COOLER MOS GUIDANCE IN THE TRIAD AND THE WARMER MOS GUIDANCE ELSEWHERE. K INDICES SLOWLY RISE SUNDAY...WITH PRECIPITABLE WATER VALUES RISING LATE SUNDAY TO BETWEEN 0.75 AND ONE INCH...ABOVE NORMAL FOR VERY EARLY DECEMBER AT ABOUT THE 75TH PERCENTILE. LIFT STARTS TO INCREASE LATE SUNDAY AND PARTICULARLY SUNDAY NIGHT AS ISENTROPIC LIFT ON THE 300K SURFACE INCREASES...WITH THE BEST POTENTIAL VORTICITY ON THE 1.5PVU SURFACE FORECAST BY THE GFS ALONG AND SOUTH OF ABOUT U.S. 64 LATE SUNDAY THROUGH SUNDAY NIGHT. SURFACE DEPICTIONS OF THE NAM AND GFS DIFFER AND ARE FAIRLY CONSISTENT WITH THEMSELVES OVER THE LAST TWO OR THREE RUNS...WITH THE NAM SHOWING A WEAK SURFACE LOW JUST OFF THE SOUTH CAROLINA COAST SUNDAY NIGHT WHILE THE GFS FORECASTS MORE OF AN INVERTED TROUGH BEFORE SURFACE LOW PRESSURE STRENGTHENS OFFSHORE. REGARDNESS...QPF AND MOS GUIDANCE POPS ARE SIMILAR... KEEPING MOST CHANCES FOR PRECIPITATION AT BAY SUNDAY AND INCREASING CHANCES OVER MOST OF CENTRAL NORTH CAROLINA SUNDAY NIGHT. WILL NOTE A SLIGHT CHANCE OF RAIN MAINLY OVER THE SANDHILLS AND SOUTHERN COASTAL PLAIN SUNDAY WHERE THE BEST LOW-LEVEL MOISTURE SHOULD RESIDE AS POTENTIAL VORTICITY INCREASES...WITH A CHANCE OF RAIN SUNDAY NIGHT MAINLY ALONG AND EAST OF A LINE FROM ABOUT KIXA TO KAFP WITH A SLIGHT CHANCE NORTH OF THAT LINE. DEBATED WHETHER OR NOT TO INCLUDE A SLIGHT CHANCE IN THE TRIAD AND FOR THIS FORECAST WILL SHOW A VERY LOW SLIGHT CHANCE THERE OVERNIGHT SUNDAY...THOUGH THIS COULD END UP BEING OVERDONE WITH SUFFICIENT MOISTURE AND LIFT REMAINING JUST EAST. SURFACE WET BULB TEMPERATURES AND PARTIAL THICKNESSES SUPPORT ALL LIQUID. ONCE AGAIN 1000-850MB THICKNESSES WOULD SUPPORT HIGHS SUNDAY ABOVE MOS GUIDANCE...BUT GIVEN THE EXPECTED CLOUD COVER...WILL FORECAST HIGHS AS A BLEND OF MAV AND MET MOS GUIDANCE FOR A FAIRLY UNIFORM LOWER 50S IN MOST LOCATIONS. OVERNIGHT SUNDAY...IF IT REMAINS DRY IN THE TRIAD LOWS SHOULD BE NEAR THE WARMER GUIDANCE...WHILE WHERE IT RAINS TEMPERATURES WOULD APPROACH THE DEW POINT. THIS COINCIDES WITH A BLEND OF MOS GUIDANCE...ALTHOUGH HIGHER THAN GUIDANCE TOWARD KRWI...FOR LOWS IN THE MID TO UPPER 30S NORTHWEST...TO MID 40S TOWARD KCTZ. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 235 AM SATURDAY... ON MONDAY A LOW AMPLITUDE NORTHERN STREAM SHORTWAVE DROPS INTO THE THE DEEP SOUTH AS A SHEARING SOUTHERN STREAM SYSTEM WITH A 250MB JET OF 140 KTS PHASE TOGETHER BEFORE THE TROUGH AXIS MOVES OFF THE SOUTHEAST COAST MONDAY NIGHT. THE TROUGH BECOMES NEGATIVELY TILTED AND INITIATES SURFACE CYCLOGENESIS MONDAY NIGHT AND TUESDAY. RECENT NWP TRENDS HAVE SUGGESTED A LESS AMPLIFIED SYSTEM WHILE PRODUCING A BIT MORE QPF ACROSS MAINLY SOUTHEASTERN NC. IT REMAINS DIFFICULT AND CONFIDENCE IS LOW REGARDING HOW FAR NORTH AND WEST PRECIPITATION WILL SPREAD ACROSS CENTRAL NC BUT CONFIDENCE IS GROWING THAT SOME LIGHT PRECIPITATION WILL FALL ACROSS THE SOUTHERN COASTAL PLAIN AND SANDHILLS REGION. NWP CONSENSUS SHOWS THE DEEPEST MOISTURE AND STRONGEST FORCING WILL BE CONFINED TO SOUTHEASTERN PORTIONS OF THE RAH CWA WITH RAPIDLY DECREASING RAIN CHANCES ACROSS THE NORTHERN AND WESTERN PIEDMONT. ISENTROPIC ANALYSIS DEPICTS THE PATTERN WELL WITH A FAIRLY NARROW CORRIDOR OF LIFT/SATURATION THAT SLIDES MAINLY ACROSS SOUTHERN AND EASTERN NC. PRECIPITATION CHANCES QUICKLY TAIL OFF FROM WEST TO EAST ON MONDAY NIGHT. THE AIR MASS AHEAD OF THE SYSTEM WILL HAVE MODIFIED AND THE PRECIPITATION WILL FALL AS RAIN. GIVEN THE MODIFICATION OF THE AIR MASS AND THE LIGHT PRECIPITATION CHANCES...DO NOT EXPECT A SIGNIFICANT CAD EVENT TO OCCUR. HIGHS MONDAY WILL RANGE IN THE 49-56 RANGE WITH MAX TEMPERATURES DEPENDENT ON THE LOCATION AND INTENSITY OF THE PRECIPITATION. AFTER THE UPPER TROUGH AXIS MOVES OFFSHORE...THE FLOW ALOFT BECOMES MORE NORTHWESTERLY. ANOTHER DISTURBANCE IN THE FLOW AND SOME RESIDUAL MOISTURE SHOULD BE SUFFICIENT TO PRODUCE SOME CLOUDINESS ON TUESDAY BUT OTHERWISE FAIR CONDITIONS ARE EXPECTED WITH HIGHS IN THE LOWER TO MID 50S. THE FLOW FLATTENS ON TUESDAY NIGHT AND HEIGHTS RISE ON WEDNESDAY INTO THURSDAY WITH INCREASING HIGH CLOUDS LATE WEDNESDAY AND A FAIR AMOUNT OF CLOUDS EXPECTED ON THURSDAY. EXPECT DRY WEATHER THROUGH AT LEAST THURSDAY AFTERNOON AS THE RIDGE AXIS BUILDS OVERHEAD. MODERATING TEMPERATURES ARE EXPECTED ON THURSDAY INTO FRIDAY WITH HIGHS IN THE MID TO UPPER 50S ON WEDNESDAY WARMING INTO THE UPPER 50S TO LOWER 60S ON THURSDAY WITH MORNING LOWS IN THE MID 30S TO AROUND 40. A LONGWAVE TROUGH DEVELOPS OVER THE WESTERN U.S. LATE THURSDAY INTO FRIDAY AS AN ARCTIC AIRMASS DROPS INTO THE NORTHERN ROCKIES AND NORTHERN PLAINS. AN INCREASINGLY MOIST SOUTHERLY TO SOUTHWESTERLY FLOW DEVELOPS ACROSS THE CENTRAL U.S. AS THE TROUGH PUSHES EAST ON FRIDAY. THE ASSOCIATED COLD FRONT REACHES THE WESTERN APPALACHIANS ON FRIDAY MORNING. THERE ARE TIMING DIFFERENCES AMONG THE GUIDANCE REGARDING THE EASTWARD ADVANCEMENT OF THE FRONT AND THE ASSOCIATED PRECIPITATION WITH WPC PREFERRING A GEFS MEAN AND EC ENS MEAN. REGARDLESS...THE THREAT OF RAIN WILL ARRIVE WITH LOW PROBABILITIES IN THE WEST LATE THURSDAY NIGHT. POPS WILL INCREASE FROM WEST TO EAST FRIDAY AND FRIDAY NIGHT WITH THE BEST CHANCE OF RAIN AT THIS POINT APPEARING TO BE FRIDAY NIGHT AND SATURDAY. AHEAD OF THE FRONT AND THE RAIN...TEMPERATURES ARE LIKELY TO CLIMB INTO THE 60S FRIDAY AFTERNOON. -BLAES && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 650 AM SATURDAY... VFR CONDITIONS CONTINUE THROUGH MUCH OF THE 12Z VALID TAF PERIOD. WINDS REMAIN NOTICEABLE DURING THE EARLY MORNING IN THE TIGHTER GRADIENT ON THE EAST SIDE OF THE RIDGE AXIS...AND THE KRAX WSR-88D SHOWED WINDS OF 40KT EARLIER JUST ABOVE 2K FEET...BUT THESE WINDS HAVE SINCE DIMINISHED ALMOST IN HALF SINCE 06Z. MODEL GUIDANCE SHOWS SUCH WINDS CONTINUING TO DECREASE SOME DURING THE MORNING...BUT THESE COULD TRANSLATE TO A FEW WIND GUSTS IN THE TEENS KTS AFTER SUNRISE WITH EVEN MINIMAL MIXING AT KRDU AND ESPECIALLY KFAY AND KRWI. AS HIGH PRESSURE SETTLES OVERHEAD FOR THIS EVENING...WINDS SHOULD BECOME LIGHT. AS LOW-LEVEL MOISTURE INCREASES THIS EVENING AND OVERNIGHT...THERE IS THE POTENTIAL FOR AT LEAST A PERIOD OF MVFR CEILINGS PARTICULARLY TOWARD KFAY WITH A LESSER LIKELIHOOD TOWARD KRDU AND KRWI. BEYOND THE 12Z VALID TAF PERIOD...SUB-VFR CONDITIONS ARE POSSIBLE EARLY SUNDAY MAINLY TOWARD KFAY...AND SUCH CONDITIONS ARE QUITE POSSIBLE SUNDAY NIGHT MAINLY EAST AND SOUTHEAST OF THE TRIAD AS MOISTURE INCREASES...ALONG WITH A CHANCE OF RAIN MAINLY EAST AND SOUTHEAST OF THE TRIAD. THE PROBABILITY OF SUB-VFR CONDITIONS INCREASES LATE SUNDAY NIGHT INTO MONDAY...AGAIN BEST EAST AND SOUTHEAST OF THE TRIAD...WITH IMPROVING CONDITIONS FOR TUESDAY CONTINUING INTO WEDNESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE && $$ SYNOPSIS... DJF NEAR TERM...DJF SHORT TERM...DJF LONG TERM...BLAES AVIATION...DJF
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
946 AM CST SAT NOV 30 2013 .UPDATE... ISSUED AT 946 AM CST SAT NOV 30 2013 LOWERED HIGHS FOR TODAY ACROSS THE NORTHWESTERN COUNTIES AND DROPPED THEM EVEN A DEGREE OR SO DOWN TO FARGO. CLEAR SKIES ALLOWED TEMPS AROUND KDVL TO DROP INTO THE LOWER TEENS...AND WITH STRATUS MOVING IN THERE WILL BE NOT TOO MUCH RISE THIS AFTERNOON. AT THIS TIME THE SOUTHWESTERN CWA COULD STILL SEE SOME SUN AND CLIMB INTO THE MID 30S...BUT THERE ARE MORE MID CLOUDS MOVING IN FROM THE WEST. MADE SOME FURTHER TWEAKS TO CLOUDS AND WILL KEEP AN EYE ON TEMPS IN CASE THEY NEED TO BE DROPPED MORE LATER ON TODAY. UPDATE ISSUED AT 644 AM CST SAT NOV 30 2013 WILL NEED TO INCREASE SKY TODAY. THE RAP GUIDANCE IS VERIFYING THE BEST...SHOWING THE LOW LEVEL CIGS FROM CANADA ADVECTING INTO THE FORECAST AREA. WILL FOLLOW THE 09Z RAP FOR ARRIVAL TIMES. WILL ALSO KEEP THE REGION CLOUDY THROUGH THE OVERNIGHT HOURS. FORECASTED MAX TEMPS TODAY MAY BE A BIT HIGH...BUT SHOULD BE IN THE BALL PARK. FORECASTED MIN TEMPS TONIGHT ARE LIKELY TOO COLD (IF CLOUDS STICK AROUND AS EXPECTED). WILL CONCENTRATE ON SKY FOR THIS UPDATE...AND WORRY ABOUT TEMPS WITH THE NEXT UPDATES. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 337 AM CST SAT NOV 30 2013 00Z MODELS INITIALIZED WITH MINIMAL ERRORS AND ARE IN GOOD AGREEMENT THROUGH SUNDAY. THE CHALLENGE FOR TODAY WILL BE TEMPERATURES AND CLOUD COVER. THE CHALLENGE FOR SUNDAY WILL BE -SN CHANCES. TODAY-TONIGHT...WEAK COLD FRONT WILL BE THROUGH THE REGION WHICH SHOULD LEAD TO SLIGHTLY COOLER TEMPERATURES THAN YESTERDAY. THE MID-LEVEL CLOUDS ALONG AND AHEAD OF THIS FEATURE WILL MOVE SOUTH...BUT WILL NEED TO WATCH THE LOW-LEVEL CIGS APPROACHING FROM THE NORTH. 06Z RAP IS MOST AGGRESSIVE BRINGING THESE CIGS INTO THE ENTIRE FA...WHILE MOST OTHER GUIDANCE SUGGESTS ONLY PORTIONS OF NW MN WILL BE AFFECTED. WILL SIDE WITH THE MAJORITY...AND TAKE A CLOSER LOOK AT THE 7AM UPDATE. SUNDAY...00Z MODELS HAVE SLOWED THE SHORTWAVE BRINGING -SN CHANCES...ADJUSTED POPS ACCORDINGLY. MUCH OF SUNDAY SHOULD BE DRY (UNTIL THE EVENING HOURS). .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 337 AM CST SAT NOV 30 2013 SUNDAY NIGHT-MONDAY NIGHT...00Z MODELS BEGIN TO DIVERGE...WITH THE ECMWF/GEM/UKMET DIGGING THE UPPER LOW INTO THE NW CONUS BY 12Z TUE...AND THE NAM/GFS BRINGING THIS FEATURE INTO MONTANA/WESTERN DAKOTAS. THE ECMWF/GEM/UKMET HAVE BEEN THE MORE CONSISTENT MODELS...AND ARE SUPPORTED BY ENSEMBLES (WILL FOLLOW FOR FORECAST DETAILS). THERE WILL BE A COUPLE LEAD SHORTWAVES EJECTING FROM THE MAIN UPPER TROUGH. THE FIRST WILL MOVE THROUGH THE REGION SUNDAY NIGHT...AND THE SECOND MONDAY AFTERNOON/NIGHT. SINCE THERE HAVE BEEN A FEW MODEL RUNS INDICATING THESE FEATURES...WILL INCREASE POPS TO LIKELY AND ATTEMPT TO TIME THESE FEATURES THROUGH THE REGION. THE FIRST WAVE IS WEAKER...AND SHOULD HAVE LESS AVAILABLE MOISTURE. MESOSCALE FORCING IS ALSO WEAK...SO UP TO AN INCH OF SNOWFALL APPEARS POSSIBLE (MAYBE 2 INCHES). THE SECOND WAVE IS STRONGER...WITH MORE AVAILABLE MOISTURE (PWATS APPROACHING 0.5 INCHES). MODELS INDICATE A DEFINED CIRCULATION AT 850MB (AND A WEAK 700MB LOW) PROPAGATING FROM NW ND INTO SE ND ON MONDAY...LOSING DEFINITION MONDAY NIGHT AS IT PROPAGATES FURTHER TO THE SE. ASSOCIATED WARM AIR ADVECTION/DEFORMATION COMBINED WITH THE 0.5 INCH PWATS SHOULD LEAD TO A FEW INCHES OF SNOWFALL. MODELS INDICATE 0.25-0.40 INCHES QPF ACROSS ALL BUT THE NE FA...AND COMBINED WITH 12:1-13:1 SNOW RATIOS WOULD LEAD TO AN AREA OF 3-5 INCHES OF SNOW. P-TYPE WILL BE ALL SNOW IF THE EXPECTED SOLUTION VERIFIES. THE NAM/SREF/GFS HAVE WARMER MID-LEVEL TEMPERATURES SINCE THE UPPER WAVE IS CLOSER TO THE REGION (LOW LEVEL SOUTHERLY FLOW IS STRONGER)...AND WOULD LEAD TO FZRA/RA POTENTIAL (BUT THIS PROBABILITY SEEMS VERY LOW ATTM). TUESDAY-FRIDAY...A VERY WINTRY PERIOD IS IN STORE...WITH THE MAIN FOCUS INITIALLY BEING SNOW POTENTIAL THROUGH MID-WEEK FOLLOWED BY A COLD ARCTIC AIR MASS SPILLING SOUTH. MODEL SPREAD CONTINUES TO BE SIGNIFICANT...ALTHOUGH THE ECMWF HAS SHOWN BETTER CONSISTENCY OVER THE PAST FEW RUNS...SO HAVE TRENDED A BIT IN THAT DIRECTION. THE 00Z GFS/ECMWF BOTH BRING THE UPPER TROUGH EASTWARD INTO THE PLAINS WED/THU. HOWEVER...A CHALLENGE CONTINUES TO BE TIMING OF EMBEDDED WAVES. THE ECMWF REMAINS DEEPEST AND FARTHEST WEST WITH SFC LOW DEVELOPMENT FROM THE CENTRAL PLAINS NORTHEAST INTO ONTARIO IN CONJUNCTION WITH A STRONG SHORTWAVE TROUGH ASSOCIATED WITH THE LIFTING UPPER LOW...WHILE THE GFS IS MORE PROGRESSIVE WITH A WEAKER SFC LOW ASSOCIATED WITH A LEAD WAVE. THUS...THE ECMWF AND TO A LESSER EXTENT THE GEM ARE MORE AGGRESSIVE WITH QPF. THE 500 MB GFS ENSEMBLE MEAN HEIGHT FIELD GENERALLY SUPPORTS THE ECMWF BROADLY. CONFIDENCE STILL IS RATHER LOW REGARDING THE PLACEMENT AND MAGNITUDE OF SNOWFALL...ALTHOUGH THE MID-WEEK PERIOD WILL CONTINUE TO BEAR WATCHING FOR ACCUMULATING SNOWFALL. ARCTIC AIR WILL BLAST SOUTH DURING THE LATTER PART OF THE WEEK INTO NEXT WEEKEND. THE ECMWF CONTINUES TO INDICATE 925 MB TEMPS DOWN TO -20 TO -25C THURSDAY/FRIDAY BEHIND INITIAL SURGE OF COLD ADVECTION. BLUSTERY WINDS WILL COMBINE WITH VERY COLD TEMPS TO PRODUCE POTENTIALLY HAZARDOUS WIND CHILLS AT TIMES. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 644 AM CST SAT NOV 30 2013 MAJOR CHANGE WITH THE 12Z TAF ISSUANCE TO BRING MVFR CIGS INTO THE REGION TODAY. USED THE 09Z RAP FOR HELP WITH ARRIVAL TIMES. SATELLITE IMAGERY INDICATES THESE CIGS CONTINUE TO ADVECT SOUTHWARD FROM CANADA...WITH THE RAP GUIDANCE HANDLING THIS SCENARIO THE BEST. THESE CIGS WILL LIKELY REMAIN THROUGH THE OVERNIGHT HOURS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...JR SHORT TERM...TG LONG TERM...TG/MAKOWSKI AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
644 AM CST SAT NOV 30 2013 .UPDATE... ISSUED AT 644 AM CST SAT NOV 30 2013 WILL NEED TO INCREASE SKY TODAY. THE RAP GUIDANCE IS VERIFYING THE BEST...SHOWING THE LOW LEVEL CIGS FROM CANADA ADVECTING INTO THE FORECAST AREA. WILL FOLLOW THE 09Z RAP FOR ARRIVAL TIMES. WILL ALSO KEEP THE REGION CLOUDY THROUGH THE OVERNIGHT HOURS. FORECASTED MAX TEMPS TODAY MAY BE A BIT HIGH...BUT SHOULD BE IN THE BALL PARK. FORECASTED MIN TEMPS TONIGHT ARE LIKELY TOO COLD (IF CLOUDS STICK AROUND AS EXPECTED). WILL CONCENTRATE ON SKY FOR THIS UPDATE...AND WORRY ABOUT TEMPS WITH THE NEXT UPDATES. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 337 AM CST SAT NOV 30 2013 00Z MODELS INITIALIZED WITH MINIMAL ERRORS AND ARE IN GOOD AGREEMENT THROUGH SUNDAY. THE CHALLENGE FOR TODAY WILL BE TEMPERATURES AND CLOUD COVER. THE CHALLENGE FOR SUNDAY WILL BE -SN CHANCES. TODAY-TONIGHT...WEAK COLD FRONT WILL BE THROUGH THE REGION WHICH SHOULD LEAD TO SLIGHTLY COOLER TEMPERATURES THAN YESTERDAY. THE MID-LEVEL CLOUDS ALONG AND AHEAD OF THIS FEATURE WILL MOVE SOUTH...BUT WILL NEED TO WATCH THE LOW-LEVEL CIGS APPROACHING FROM THE NORTH. 06Z RAP IS MOST AGGRESSIVE BRINGING THESE CIGS INTO THE ENTIRE FA...WHILE MOST OTHER GUIDANCE SUGGESTS ONLY PORTIONS OF NW MN WILL BE AFFECTED. WILL SIDE WITH THE MAJORITY...AND TAKE A CLOSER LOOK AT THE 7AM UPDATE. SUNDAY...00Z MODELS HAVE SLOWED THE SHORTWAVE BRINGING -SN CHANCES...ADJUSTED POPS ACCORDINGLY. MUCH OF SUNDAY SHOULD BE DRY (UNTIL THE EVENING HOURS). .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 337 AM CST SAT NOV 30 2013 SUNDAY NIGHT-MONDAY NIGHT...00Z MODELS BEGIN TO DIVERGE...WITH THE ECMWF/GEM/UKMET DIGGING THE UPPER LOW INTO THE NW CONUS BY 12Z TUE...AND THE NAM/GFS BRINGING THIS FEATURE INTO MONTANA/WESTERN DAKOTAS. THE ECMWF/GEM/UKMET HAVE BEEN THE MORE CONSISTENT MODELS...AND ARE SUPPORTED BY ENSEMBLES (WILL FOLLOW FOR FORECAST DETAILS). THERE WILL BE A COUPLE LEAD SHORTWAVES EJECTING FROM THE MAIN UPPER TROUGH. THE FIRST WILL MOVE THROUGH THE REGION SUNDAY NIGHT...AND THE SECOND MONDAY AFTERNOON/NIGHT. SINCE THERE HAVE BEEN A FEW MODEL RUNS INDICATING THESE FEATURES...WILL INCREASE POPS TO LIKELY AND ATTEMPT TO TIME THESE FEATURES THROUGH THE REGION. THE FIRST WAVE IS WEAKER...AND SHOULD HAVE LESS AVAILABLE MOISTURE. MESOSCALE FORCING IS ALSO WEAK...SO UP TO AN INCH OF SNOWFALL APPEARS POSSIBLE (MAYBE 2 INCHES). THE SECOND WAVE IS STRONGER...WITH MORE AVAILABLE MOISTURE (PWATS APPROACHING 0.5 INCHES). MODELS INDICATE A DEFINED CIRCULATION AT 850MB (AND A WEAK 700MB LOW) PROPAGATING FROM NW ND INTO SE ND ON MONDAY...LOSING DEFINITION MONDAY NIGHT AS IT PROPAGATES FURTHER TO THE SE. ASSOCIATED WARM AIR ADVECTION/DEFORMATION COMBINED WITH THE 0.5 INCH PWATS SHOULD LEAD TO A FEW INCHES OF SNOWFALL. MODELS INDICATE 0.25-0.40 INCHES QPF ACROSS ALL BUT THE NE FA...AND COMBINED WITH 12:1-13:1 SNOW RATIOS WOULD LEAD TO AN AREA OF 3-5 INCHES OF SNOW. P-TYPE WILL BE ALL SNOW IF THE EXPECTED SOLUTION VERIFIES. THE NAM/SREF/GFS HAVE WARMER MID-LEVEL TEMPERATURES SINCE THE UPPER WAVE IS CLOSER TO THE REGION (LOW LEVEL SOUTHERLY FLOW IS STRONGER)...AND WOULD LEAD TO FZRA/RA POTENTIAL (BUT THIS PROBABILITY SEEMS VERY LOW ATTM). TUESDAY-FRIDAY...A VERY WINTRY PERIOD IS IN STORE...WITH THE MAIN FOCUS INITIALLY BEING SNOW POTENTIAL THROUGH MID-WEEK FOLLOWED BY A COLD ARCTIC AIR MASS SPILLING SOUTH. MODEL SPREAD CONTINUES TO BE SIGNIFICANT...ALTHOUGH THE ECMWF HAS SHOWN BETTER CONSISTENCY OVER THE PAST FEW RUNS...SO HAVE TRENDED A BIT IN THAT DIRECTION. THE 00Z GFS/ECMWF BOTH BRING THE UPPER TROUGH EASTWARD INTO THE PLAINS WED/THU. HOWEVER...A CHALLENGE CONTINUES TO BE TIMING OF EMBEDDED WAVES. THE ECMWF REMAINS DEEPEST AND FARTHEST WEST WITH SFC LOW DEVELOPMENT FROM THE CENTRAL PLAINS NORTHEAST INTO ONTARIO IN CONJUNCTION WITH A STRONG SHORTWAVE TROUGH ASSOCIATED WITH THE LIFTING UPPER LOW...WHILE THE GFS IS MORE PROGRESSIVE WITH A WEAKER SFC LOW ASSOCIATED WITH A LEAD WAVE. THUS...THE ECMWF AND TO A LESSER EXTENT THE GEM ARE MORE AGGRESSIVE WITH QPF. THE 500 MB GFS ENSEMBLE MEAN HEIGHT FIELD GENERALLY SUPPORTS THE ECMWF BROADLY. CONFIDENCE STILL IS RATHER LOW REGARDING THE PLACEMENT AND MAGNITUDE OF SNOWFALL...ALTHOUGH THE MID-WEEK PERIOD WILL CONTINUE TO BEAR WATCHING FOR ACCUMULATING SNOWFALL. ARCTIC AIR WILL BLAST SOUTH DURING THE LATTER PART OF THE WEEK INTO NEXT WEEKEND. THE ECMWF CONTINUES TO INDICATE 925 MB TEMPS DOWN TO -20 TO -25C THURSDAY/FRIDAY BEHIND INITIAL SURGE OF COLD ADVECTION. BLUSTERY WINDS WILL COMBINE WITH VERY COLD TEMPS TO PRODUCE POTENTIALLY HAZARDOUS WIND CHILLS AT TIMES. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 644 AM CST SAT NOV 30 2013 MAJOR CHANGE WITH THE 12Z TAF ISSUANCE TO BRING MVFR CIGS INTO THE REGION TODAY. USED THE 09Z RAP FOR HELP WITH ARRIVAL TIMES. SATELLITE IMAGERY INDICATES THESE CIGS CONTINUE TO ADVECT SOUTHWARD FROM CANADA...WITH THE RAP GUIDANCE HANDLING THIS SCENARIO THE BEST. THESE CIGS WILL LIKELY REMAIN THROUGH THE OVERNIGHT HOURS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...TG SHORT TERM...TG LONG TERM...TG/MAKOWSKI AVIATION...TG
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
543 AM CST SAT NOV 30 2013 .UPDATE... 12Z AVIATION DISCUSSION BELOW... && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH MONDAY CHANCES FOR PRECIPITATION AS WELL AS P-TYPE WILL BE THE FORECAST CHALLENGES. A WEAK MID LEVEL SHORT WAVE CURRENTLY OVER MONTANA WILL TRACK SOUTHEASTWARD ACROSS THE REGION TODAY...BRINGING PARTLY CLOUDY SKIES TO THE CWA. THE PAST FEW RUNS OF THE RUC AND THE NSSL WRF BOTH SHOW SOME LIGHT RAIN FOR THE FAR NW PORTION OF THE CWA...PERHAPS REACHING KMBG BY THIS AFTERNOON. THUS HAVE ADDED A LOW POP. ANOTHER MID LEVEL SHORT WAVE AND FRONTAL BOUNDARY WILL TRACK ACROSS THE REGION ON SUNDAY. MODELS HAVE SIGNIFICANTLY SLOWED DOWN THE PROGRESSION OF THE TROUGH...WITH PCPN NOT REACHING THE JAMES RIVER VALLEY UNTIL AFTER 18Z. IT STILL APPEARS AS THOUGH THE LEADING EDGE OF THE PCPN WILL FALL AS ALL SNOW. HOWEVER WITH WAA QUICKLY PUSHING IN ON THE BACK SIDE...THE SNOW WILL TRANSITION OVER TO ALL RAIN. THIS SYSTEM DOES NOT CONTAIN A GREAT DEAL OF LOW LEVEL MOISTURE SO WILL MAINTAIN CHC POP ALONG THE ND/SD BORDER FOR NOW. A MUCH STRONGER STORM SYSTEM WILL BEGIN IMPACTING THE REGION ON MONDAY. HOWEVER MODEL ARE NOT IN A REAL GOOD AGREEMENT WITH THE OVERALL PLACEMENT OF THIS MID LEVEL CLOSED LOW...WHICH LEADS TO A LOW FORECASTER CONFIDENCE. EVEN WITH A DISAGREEMENT ON THE PLACEMENT THERE IS A GENERAL CONSENSUS THAT TEMPERATURES WILL BE WARM ENOUGH TO SUPPORT A MOSTLY RAIN EVENT. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY STILL NOT A LOT OF CONFIDENCE WITH THE FINER DETAILS WITHIN THE EXTENDED...THOUGH TWO GENERAL TRENDS CAN BE EXPECTED. THE FIRST WILL BE THE INFLUENCE OF A BROAD UPPER TROF AND EMBEDDED SHORTWAVES MOVING ACROSS THE NORTHERN TIER CONUS. MOST OF THE PRECIPITATION WILL BE ASSOCIATED WITH AN H7 LOW THAT LOOKS TO TRACK ACROSS NORTH DAKOTA/MINNESOTA...THOUGH IT MAY PIVOT THROUGH WESTERN SOUTH DAKOTA DEPENDING ON THE MODEL. THIS TRACK SUGGESTS NORTH DAKOTA WILL RECEIVE THE MAJORITY OF PRECIPITATION WITHIN THE WARM ADVECTION BAND AND ANY TROWAL BASED WRAP AROUND. THE GFS IS GENERALLY WEAKER WITH SIGNIFICANTLY LOWER PRECIPITATION POTENTIAL. THE ECMWF IS STRONGER...WITH A MORE SOUTHERLY TRACK...AND STRONGER WINDS WITH POTENTIALLY MORE IMPACTS TO THE CWA. THE SECOND FEATURE WILL BE ANOMALOUSLY COLD AIR POURING INTO THE REGION. TIMING DIFFERENCES CONTINUE BETWEEN THE GFS AND ECMWF...VARYING BETWEEN TUESDAY AND WEDNESDAY RESPECTIVELY. BOTH MODELS RESOLVE THE COLD POOL WITH SIMILAR INTENSITY AND DURATION...AS IT WILL COME TO DOMINATE THE WEATHER THROUGH THE END OF THE WORK WEEK. UNFORTUNATELY...BOTH MODELS HAVE BEEN REASONABLY CONSISTENT WITH THEIR INDIVIDUAL TRENDS. WILL CONTINUE TO BROADBRUSH THE FIRST FEW PERIODS OF THE EXTENDED WITH CHANCE POPS/SNOW UNTIL MODELS ENTER BETTER ALIGNMENT. && .AVIATION... 12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS EXPECTED AT ALL TERMINALS. LIGHT WINDS WILL BE OUT OF THE NORTHWEST GRADUALLY SHIFTING TO THE NORTH. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...CONNELLY SHORT TERM...SD LONG TERM...CONNELLY AVIATION...CONNELLY WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
404 PM CST SAT NOV 30 2013 .DISCUSSION... 252 PM CST SYNOPSIS...MORE SEASONAL TEMPERATURES WILL BE WITH US THROUGH EARLY NEXT WEEK...WITH TEMPS PEAKING MID WEEK. THEN TEMPS QUICKLY FALL TO WELL BELOW NORMAL BY NEXT WEEKEND. THERE A FEW SLIGHT CHANCES OF PRECIP EARLY NEXT WEEK WITH A MUCH BETTER CHANCE FOR PRECIP MID WEEK. THE MID WEEK SYSTEM WILL BRING MOSTLY RAIN WITH A CHANCE OF WINTRY PRECIP LATE NEXT WEEK. REST OF TODAY THROUGH SUNDAY... WEAK LOW PRESSURE IS OVER LAKE SUPERIOR AND NORTHERN WI WITH ITS COLD FRONT STRETCHING FROM MEDFORD WI THROUGH MASON CITY IA. THE LOW WILL CONTINUE EASTWARD AND DISSIPATE OVER THE EASTERN GREAT LAKES SUNDAY NIGHT. WE HAVE MIXED MUCH MORE THAN WE WERE EXPECTING TODAY...RESULTING IN HIGH TEMPS IN THE LOWER 50S. NOT BAD FOR LATE NOVEMBER! AS SUCH RAISED LOW TEMPS BY A COUPLE DEGREES TONIGHT. CLOUDS WILL ALSO BE INCREASING THIS EVENING AND OVERNIGHT LIMITING COOLING. AN UPPER LEVEL SHORTWAVE PASSES OVERHEAD TOMORROW MORNING WITH NO PRECIP EXPECTED. CAA ALOFT AND WEAK SURFACE FLOW LEAD ME TO BELIEVE WE WILL BE A BIT COOLER TOMORROW WITH HIGHS AROUND 40. MONDAY AND TUESDAY... ANOTHER SLIGHTLY DEEPER UPPER LEVEL SHORTWAVE ARRIVES MONDAY. THIS TROUGH IS ALSO FURTHER SOUTH MOVING RIGHT OVER NORTHERN IL...WHICH MAY PROVIDE JUST ENOUGH FORCING FOR A LITTLE LIGHT PRECIP. TEMPS WILL BE ON THE RISE THROUGH THE MORNING SO WENT WITH LIGHT SNOW AT FIRST TURNING OVER TO RAIN BY MONDAY AFTERNOON. THE PRECIP WILL TRAVEL EAST WITH THE SHORTWAVE THROUGH THE DAY. HIGH TEMPS ON MONDAY WILL ONCE AGAIN BE AROUND 40. AN UPPER LEVEL VORT STREAMER PASSES JUST TO THE NORTH LATE MONDAY NIGHT WHICH MAY PRODUCE A LITTLE LIGHT SNOW OVER NORTH CENTRAL IL. MAY SEE A LITTLE MORE PRECIP COVERAGE TUESDAY MORNING WITH PRECIP TURNING OVER TO RAIN AS TEMPS WARM. THE FORCING THEN LIFTS OFF TO THE NE SO KEPT A SLIGHT CHANCE OF PRECIP OVER NORTH CENTRAL IL TUESDAY AFTERNOON WITH THE MAJORITY OF PRECIP STAYING NORTH OF OUR REGION CLOSER TO THE VORT STREAMER. A STATIONARY FRONT THEN STRETCHES OVER NORTHERN IL TUESDAY NIGHT SO KEPT A SLIGHT CHANCE TO CHANCE OF RAIN GOING. WAA ALOFT WILL KEEP TUESDAY NIGHT TEMPS ABOVE FREEZING. WEDNESDAY THROUGH FRIDAY... THE UPPER LEVEL RIDGE SHIFTS TO THE EAST WITH SOUTHWEST FLOW SETTING UP THROUGH LATE FRIDAY. THE UPPER LEVEL TROUGH AXIS PASSES OVERHEAD SATURDAY. LONG DISTANCE GUIDANCE AGREES ON THE OVERALL PATTERN...BUT THE GFS AND ECMWF DIFFER GREATLY ON WHEN THESE FEATURES WILL IMPACT THE REGION. WENT WITH THE MORE STEADY ECMWF IN THE LONG TERM AS THE GFS LOOKS MUCH TOO FAST. A SURFACE LOW MOVES OVER THE CENTRAL PLAINS LATE TUESDAY NIGHT INTO WEDNESDAY WITH WAA IMPACTING THE REGION TUESDAY NIGHT THROUGH WEDNESDAY EVENING. WITH ALL OF THE WAA RAISED TEMPS TUESDAY NIGHT AND WEDNESDAY...AND HONESTLY...STILL THINK TEMPS ARE TOO LOW. COULD EASILY SEE AT LEAST LOW 50S ON WEDNESDAY. RAIN ARRIVES BEHIND THE WARM FRONT WEDNESDAY AFTERNOON WITH GUIDANCE BACKING OFF A LITTLE WITH QPF...TO AROUND 0.1 INCHES. THE LOWS COLD FRONT SWINGS THROUGH WED NIGHT/THURSDAY WITH TEMPS CRASHING BEHIND IT. COULD EASILY SEE A 10+ DEGREE DIFFERENCE IN HIGH TEMPS WEDNESDAY AND THURSDAY. PRECIP MAY LINGER A BIT BEHIND THE COLD FRONT...MEANING WINTRY PRECIP IS POSSIBLE. GUIDANCE INDICATES PRECIP WILL ALSO FORM AHEAD OF THE UPPER LEVEL TROUGH AXIS...RESULTING IN RAIN/SNOW THURSDAY BECOMING ALL SNOW THURSDAY NIGHT THROUGH LATE FRIDAY. ARCTIC AIR MOVES IN WITH THE TROUGH AXIS RESULTING IN HIGH TEMPS IN THE 20S LATE NEXT WEEK. MAY EVEN SEE HIGH TEMPS IN THE TEENS ON SATURDAY. CONFIDENCE IS HIGH THAT THE SYSTEM WILL IMPACT THE REGION MID NEXT WEEK...PRECIP WILL BE MOSTLY RAIN...AND IN TEMP TRENDS. MEDIUM CONFIDENCE IN HOW LONG PRECIP WILL LINGER. JEE && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 22Z... * MVFR CIGS POSSIBLE SUNDAY MORNING IZZI //DISCUSSION...UPDATED 18Z... HIGH PRESSURE WAS OVER NEW ENGLAND AND WEAK LOW PRESSURE WAS OVER LAKE SUPERIOR AT MIDDAY...WITH A COLD FRONT TRAILING THROUGH NORTHWEST WISCONSIN AND IOWA. SOUTHWEST FLOW AHEAD OF THE FRONT WAS BRINGING MILD DRY AIR TO THE REGION. A FAIRLY SHALLOW INVERSION IS IN PLACE BUT WITH FULL SUN THERE IS ENOUGH MIXING FOR A FEW GUSTS IN THE MID TO UPPER TEENS THIS AFTERNOON. LATE THIS AFTERNOON WITH LOSS OF HEATING AND MIXING...WINDS AND GUSTS WILL DIMINISH. WINDS WILL GRADUALLY VEER FROM SSW TO SW TO WSW THROUGH THE EVENING HOURS AS THE FRONT APPROACHES. WINDS WILL BE LIGHT AS THE WEAK FRONT SLIPS THROUGH THE AREA. NEW SHORT RANGE MODELS ALL VERY SIMILAR IN TIMING OF THE FRONTAL PASSAGE THROUGH THE TERMINALS. WINDS WILL QUICKLY SHIFT TO NW BEHIND THE FRONT...THEN GRADUALLY CONTINUE TO COME AROUND TO NNE DURING THE DAY SUNDAY. MAIN CONCERN IS FOR THE POTENTIAL OF MVFR CIG AND SOME LIGHT FOG AND HAZE IN THE EARLY MORNING BEHIND THE FRONT. NAM AND LOCAL ARW MOST AGGRESSIVE IN MOISTENING LOWEST PART OF SOUNDING. THIS WOULD SUGGEST CIGS AT OR BELOW 1000 FT WITH SOME FOG AND HAZE. GFS KEEPS INVERSION AROUND 2500 FT. TIMING OF STRATUS COULD BE DELAYED A FEW HOURS AFTER FROPA. FOR NOW WILL CONTINUE TREND OF PREVIOUS FORECAST WITH CIGS AROUND 2K FT AFTER FROPA. ALLSOPP //ORD AND MDW CONFIDENCE...UPDATED 22Z... * HIGH CONFIDENCE IN WIND FORECAST * HIGH CONFIDENCE IN VFR CONDITIONS THROUGH TONIGHT * LOW/MEDIUM CONFIDENCE ON MVFR CIGS SUNDAY MORNING IZZI //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...VFR...THOUGH MVFR CIGS POSSIBLE. MONDAY INTO TUESDAY...MVFR CIGS POSSIBLE. SLIGHT CHANCE -RASN. WEDNESDAY...MVFR CIGS PROBABLE CHANCE OF IFR. CHANCE OF RAIN. THURSDAY...MVFR CIGS PROBABLE. CHANCE -RASN. FRIDAY...VFR. RATZER && .MARINE... 252 PM CST WINDS WILL TURN NORTH TONIGHT THROUGH THE OVERNIGHT BEHIND A COLD FRONT...BUT WILL BE LIGHTER AT 20 KT OR LESS DUE TO A WEAK PRESSURE GRADIENT. THE GENERALLY LIGHT WIND REGIME WILL CONTINUE SUNDAY INTO TUESDAY MORNING WITH WINDS GRADUALLY SHIFTING FROM NORTHEAST TO SOUTHEAST. UNCERTAINTY THEN INCREASES AMONGST MEDIUM RANGE GUIDANCE WITH TRACK AND TIMING OF LOW PRESSURE SYSTEM MOVING EAST FROM THE PLAINS. WITH THIS FORECAST PACKAGE HAVE FAVORED A SLOWER TIMING OF THIS SYSTEM...WHICH WILL RESULT IN INCREASINGLY STRONG SOUTHEAST TO SOUTH WINDS TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. A COLD FRONT IS THEN EXPECTED TO SWEEP ACROSS THE LAKE ON THURSDAY AS THE LOW TRACKS TO OR NORTH OF LAKE SUPERIOR BY THURSDAY. THIS WILL RESULT IN STRONGER SOUTHWEST TO WESTERLY WINDS. THE POTENTIAL EXISTS FOR A PERIOD OR TWO OF GALES IN ASSOCIATION WITH THIS SYSTEM...BUT DUE TO THE UNCERTAINTY...THERE ARE NO GALES IN THE FORECAST YET. THE ACTIVE PATTERN OVER THE LAKE THEN LOOKS TO CONTINUE INTO NEXT WEEKEND. RC && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
  [top] Area Forecast Discussion National Weather Service Lincoln IL 336 PM CST Sat Nov 30 2013 .DISCUSSION... ISSUED 335 PM CST Sat Nov 30 2013 A relatively mild weather pattern will start out the first few days of December, before our next best chance of precipitation and much colder air moves in for the latter part of the week. The short range models are in fair agreement into the first part of next week. However, the medium range solutions diverge significantly by mid-week which has pretty big implications on the forecast. SHORT TERM...Tonight through Monday A weak cold front from western WI across southern MN and South Dakota is expected to approach central IL Sunday morning. Ahead of this front, a light wind and dew points mainly in the lower 30s could result in some light fog and few low clouds late tonight and early Sunday morning. The NAM model is hitting this harder than the others, which it has been doing more so lately and seems to have this tendency in the cool season. Will go with partly cloudy conditions for now and monitor this evening. Mild conditions are expected on Sunday, with readings of 45 to 50 in central IL and the lower 50s south of I-70. The forecast gets a bit tricky for Sunday night into Monday as a shortwave in the WNW flow approaches the state. Many of the short range model solutions are depicting the potential for light rain as early as late Sunday night and during the day Monday. Will hold off on any mention for Sunday night into early Monday morning because of a fairly thick layer of dry air expected between 850-925 mb. Will stick with the slight chance for rain during the day Monday as a bit stronger lift could produce isolated pockets of light rain. LONG TERM...Tuesday through Saturday There are quiet significant model differences between the GFS, Canadian and European solutions starting Tuesday, which continues right through the rest of the forecast period. The GFS is much quicker with shifting an upper level low from the Pacific NW across the northern states. However, while it is doing this, it is also digging a portion of the upper level energy toward the southwestern U.S. This should result in upper level ridging in the Midwest, which would force any northern energy up into central Canada. The GFS does not do this though, which results in a cold front moving through late Tuesday/early Wednesday. The European and Canadian model solutions make much more sense by holding off on the frontal passage at least 24-36 hours later, on early Thursday. Several shortwaves moving up from the southwest, and a slowing front expected to become parallel to the flow aloft will mean periods of precipitation from Wednesday through much of Friday. Rain will be the primary precipitation type at onset on Wednesday, but then as colder air gradually advects toward the region, a mixture changing to snow is anticipated - primarily later in the day Thursday, and especially Friday. The best low level moisture and forcing is expected to the east and south of our region - closer to the frontal position - near the Ohio Valley. Thus, at this time we are not anticipating any major snow amounts, but with the complex evolution of this system and the fact that it is six days away, the confidence factor is not very high either way. Miller && .AVIATION... ISSUED 1105 AM CST Sat Nov 30 2013 High pressure sliding to the east giving way to increasing RH in the region resulting in a troublesome forecast for the overnight hours in ILX terminals. NAM has far more moisture trapped in the boundary layer and guidance resulting in everything from MVFR vis to LIFR cigs and vis. GFS in the same shape with less moisture and the HRRR is a little slower and more conservative but still moisture laden particularly NW of the Illinois River Valley. Trouble is, lower res models have increased moisture already in central MO, and sat imagery pointing to an overdone model run. That being said, dewpoints are on the increase with swrly flow. HRRR depiction of sfc RH a little more on track and def highlighting overnight NW of the IL river. Trouble is whether or not we are looking at stratus developing or vis drop. Not to mention that if enough moisture makes it into the SE and does not mix out this afternoon, chance for reduced vis in the SE as the skies clear out a bit tonight. For now, forecast conservative, but starting the trend for a visibility drop with majority rule to a cloud deck in the 4000 to 5000 ft range for PIA BMI and SPI this evening and through the overnight. HJS && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1152 AM CST SAT NOV 30 2013 .DISCUSSION... 1051 AM CST MORNING UPDATE... MIXING HEIGHTS ARE FAIRLY SHALLOW TODAY...BUT SOUTH-SOUTHWEST WARM ADVECTION PATTERN AND FULL SUNSHINE ARE RESULTING IN A MUCH MORE PLEASANT DAY THAN WE HAVE SEEN OF LATE. TEMPERATURES WERE INITIALLY SLOW TO RISE THIS MORNING...BUT SINCE HAVE BEEN QUICKLY WARMING. BASED ON TRENDS AND EXPECTATIONS OF CONTINUED STEADY WARMING UNTIL ABOUT 3PM...HAVE BUMPED UP HIGH TEMPERATURES TO THE MID AND UPPER 40S NORTH OF I-80 AND UPPER 40S TO LOCALLY AROUND 50 SOUTH OF I-80. WILL CONTINUE TO MONITOR TEMPERATURE TRENDS...AS SOME SHORT RANGE GUIDANCE INDICATES THE POTENTIAL TO WARM EVEN A BIT MORE THAN THIS. RC //PREV DISCUSSION... 248 AM CST PRIMARY FORECAST CHALLENGE WILL BE PINNING DOWN BEST CHANCES FOR PRECIP AS PATTERN BECOMES ACTIVE NEXT WEEK... THIS WEEKEND... QUIET WEATHER SHOULD PREVAIL LOCALLY AS DEPARTING HIGH PRESSURE ALLOWS RETURN FLOW INTO THE UPPER MIDWEST TO HELP MODERATE TEMPERATURES THIS AFTERNOON. GUIDANCE IN PRETTY GOOD AGREEMENT INDICATING LOW TO MID 40S ACROSS THE CWA TODAY. BLENDED TOWARDS NAM WHICH HAS A DECENT ALBEIT TOO FAR SOUTH AND TOO BROAD A HANDLE ON THE SNOWFALL CURRENTLY ON THE GROUND ACROSS THE FAR NORTHERN CWA...BUT INDICATES THOSE AREAS WILL NOT GET OUT OF THE UPPER 30S THIS AFTERNOON. A CLIPPER SYSTEM WILL BRING SNOW TO THE NORTHERN LAKES REGION THIS WEEKEND...BUT A TRAILING COLD FRONT WHICH WILL PASS OVER THE LOCAL AREA TONIGHT AND EARLY SUNDAY WILL BE MOISTURE STARVED AND LIKELY NOT PRODUCE ANY PRECIPITATION. THE CAVEAT...NAM GUIDANCE IN PARTICULAR CONTINUES TO INDICATE A SHALLOW POST FRONTAL STRATUS DECK WITH WEAK HEIGHT FALLS AS A SHEARED UPPER WAVE PUSHES ACROSS THE AREA...WHICH MAY CULMINATE IN LIGHT FREEZING DRIZZLE. BUT GIVEN THE NAMS LOW LEVEL MOISTURE BIAS AND THE GFS BACKING OFF ON A STRONGER UPPER WAVE THAT PREVIOUS RUNS WERE ADVERTISING...WILL CONTINUE TO MAINTAIN A DRY FORECAST. MONDAY AND TUESDAY... STRONG UPPER LOW DIGGING ACROSS THE PAC NW THIS PERIOD WILL RESULT IN DOWNSTREAM AMPLIFICATION OF LONGWAVE RIDGE AS STRONG WARM ADVECTION DEVELOPS ACROSS THE MID/UPPER MISSISSIPPI VALLEY. MID LEVEL THERMAL RIBBON WILL SET UP FROM THE DAKOTAS SOUTHEAST INTO THE MID MISSISSIPPI VALLEY WITH ISENTROPIC ASCENT RESULTING IN PRECIPITATION WHICH APPEARS WILL BE FOCUSED JUST TO OUR WEST MONDAY...THOUGH GUIDANCE CONTINUES TO STRUGGLE LOCKING ONTO DETAILS. THERE MAY BE A SUBTLE WAVE THAT MOVES ACROSS THE AREA...WHICH ECMWF AND NAM SUGGEST WILL BRING LIGHT PRECIP TO THE AREA EARLY MONDAY. PRETTY DRY MIDLEVEL AIRMASS THOUGH MAY BE INSURMOUNTABLE...SO CAPPED POPS AT SLIGHT CHC MONDAY. THERMAL RIDGE WILL GRADUALLY TRANSLATE ENE MONDAY NIGHT AND SHOULD EVENTUALLY SPREAD ACROSS THE CWA. MOISTURE AVAILABILITY STILL A BIG QUESTION MARK WITH RESPECT TO TIMING THE ONSET OF PRECIPITATION...BUT MORE PERSISTENT FORCING SHOULD EVENTUALLY SATURATE THE COLUMN. PRECIP SHOULD START AS SNOW...OR POSSIBLY RAIN SNOW MIX BEFORE TRANSITIONING TO ALL RAIN TUESDAY AS WE CONTINUE TO WARM THE COLUMN. WEDNESDAY AND THURSDAY... ELONGATED SURFACE LOW IS PROGGED TO LIFT NORTHEAST ACROSS THE UPPER MIDWEST INTO THE NORTHERN LAKES REGION WEDNESDAY INTO THURSDAY. AS THE WARM FRONT LIFTS NORTH ACROSS THE AREA...CONTINUE TO FEEL THAT 50S MAY OVERSPREAD AT LEAST THE SOUTHERN HALF OF THE CWA IF NOT INTO THE CHICAGO METRO AREA WEDNESDAY AFTERNOON...DESPITE CLOUD COVER AND PRECIP CHANCES. LATEST EMCWF TAKES THE 50 ISOTHERM ALL THE WAY TO THE STATE LINE...AND OFTEN IS ONE OF THE BETTER PERFORMING MODELS UNDER A THERMAL RIDGE. REMAIN CONSERVATIVE BRINGING THE WARMTH NORTHWARD...BUT DID TREND TEMPERATURES UP A COUPLE DEGREES FROM GOING FORECAST. THERE CONTINUES TO BE CONSIDERABLE SPREAD IN MODEL SOLUTIONS RESULTING IN LOW CONFIDENCE PARTICULARLY WITH TIMING PRECIP...THOUGH CONFIDENCE IN WIDESPREAD PRECIP OVERSPREADING THE AREA AT SOME POINT IS FAIRLY HIGH AS THE WARM CONVEYOR BELT TRANSLATES EAST ACROSS THE REGION WEDNESDAY/WEDNESDAY NIGHT. A COLD FRONT WILL THEN SWEEP ACROSS THE AREA LATE WEDNESDAY NIGHT INTO THURSDAY WITH PRECIP CHANGING OVER TO SNOW BRIEFLY BEFORE ENDING. AT THIS POINT DO NOT ANTICIPATE ANY ACCUMULATIONS WITH THE BULK OF THE PRECIP LIQUID. LEANED HEAVILY ON BLEND OF EMCWF AND GEM GUIDANCE FOR TIMING POPS WHICH WERE BETTER CLUSTERED COMPARED TO THE MUCH FASTER GFS. DEUBELBEISS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * WEAK COLD FRONT WILL TURN WINDS FROM SW TO NNW LATE TONIGHT. * MVFR CIG WILL LIKELY DEVELOP BEHIND COLD FRONT SUNDAY MORNING AND PERSIST THROUGH THE DAY SUNDAY. ALLSOPP //DISCUSSION...UPDATED 18Z... HIGH PRESSURE WAS OVER NEW ENGLAND AND WEAK LOW PRESSURE WAS OVER LAKE SUPERIOR AT MIDDAY...WITH A COLD FRONT TRAILING THROUGH NORTHWEST WISCONSIN AND IOWA. SOUTHWEST FLOW AHEAD OF THE FRONT WAS BRINGING MILD DRY AIR TO THE REGION. A FAIRLY SHALLOW INVERSION IS IN PLACE BUT WITH FULL SUN THERE IS ENOUGH MIXING FOR A FEW GUSTS IN THE MID TO UPPER TEENS THIS AFTERNOON. LATE THIS AFTERNOON WITH LOSS OF HEATING AND MIXING...WINDS AND GUSTS WILL DIMINISH. WINDS WILL GRADUALLY VEER FROM SSW TO SW TO WSW THROUGH THE EVENING HOURS AS THE FRONT APPROACHES. WINDS WILL BE LIGHT AS THE WEAK FRONT SLIPS THROUGH THE AREA. NEW SHORT RANGE MODELS ALL VERY SIMILAR IN TIMING OF THE FRONTAL PASSAGE THROUGH THE TERMINALS. WINDS WILL QUICKLY SHIFT TO NW BEHIND THE FRONT...THEN GRADUALLY CONTINUE TO COME AROUND TO NNE DURING THE DAY SUNDAY. MAIN CONCERN IS FOR THE POTENTIAL OF MVFR CIG AND SOME LIGHT FOG AND HAZE IN THE EARLY MORNING BEHIND THE FRONT. NAM AND LOCAL ARW MOST AGGRESSIVE IN MOISTENING LOWEST PART OF SOUNDING. THIS WOULD SUGGEST CIGS AT OR BELOW 1000 FT WITH SOME FOG AND HAZE. GFS KEEPS INVERSION AROUND 2500 FT. TIMING OF STRATUS COULD BE DELAYED A FEW HOURS AFTER FROPA. FOR NOW WILL CONTINUE TREND OF PREVIOUS FORECAST WITH CIGS AROUND 2K FT AFTER FROPA. ALLSOPP //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH CONFIDENCE IN WIND FORECAST. * MEDIUM TO HIGH CONFIDENCE IN MVFR CIG DEVELOPING BUT LOW CONFIDENCE IN TIMING AND HEIGHT OF CIG. ALLSOPP //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...VFR...THOUGH MVFR CIGS POSSIBLE. MONDAY INTO TUESDAY...MVFR CIGS POSSIBLE. SLIGHT CHANCE -RASN. WEDNESDAY...MVFR CIGS PROBABLE CHANCE OF IFR. CHANCE OF RAIN. THURSDAY...MVFR CIGS PROBABLE. CHANCE -RASN. FRIDAY...VFR. RATZER && .MARINE... 302 AM CST MAIN MARINE FORECAST CONCERNS ARE STRONG SOUTH WINDS AND GALES ON THE NORTHERN PART OF THE LAKE THIS MORNING...AND TIMING OF A STRONG LOW PRESSURE SYSTEM EXPECTED TO AFFECT THE WESTERN GREAT LAKES REGION TOWARD THE MIDDLE OF NEXT WEEK. STRONG HIGH PRESSURE WAS OVER NEW ENGLAND THIS MORNING...AND WILL MOVE SLOWLY EAST OFF OF THE ATLANTIC COAST TODAY. LOW PRESSURE OVER THE DAKOTAS WILL TRACK EAST ACROSS LAKE SUPERIOR TODAY...THEN SOUTHEAST ACROSS THE EASTERN LAKES TONIGHT. IN THE PROCESS...A COLD FRONT TRAILING FROM THIS LOW WILL MOVE SOUTHEAST ACROSS LAKE MICHIGAN LATE THIS AFTERNOON AND TONIGHT. WITH THE STRONG HIGH TO THE EAST AND THE LOW PASSING TO THE NORTH...THE SURFACE PRESSURE GRADIENT HAS TIGHTENED AND WAS PRODUCING SOUTH WINDS 30-35 KT ACROSS THE NORTHERN PART OF THE LAKE...AND NEAR 30 KT SOUTH. THIS WILL CONTINUE THROUGH THE MID-MORNING HOURS TODAY...BEFORE THE GRADIENT WEAKENS WITH THE APPROACH OF THE LOW AND COLD FRONTAL TROUGH. THIS WILL ALLOW WINDS TO DIMINISH...EVENTUALLY VEERING TO THE NORTH BEHIND THE COLD FRONT AND THEN BECOMING NORTH-NORTHEAST ON SUNDAY. HIGH PRESSURE WILL THEN SPREAD EAST ACROSS ONTARIO AND QUEBEC SUNDAY INTO MONDAY...WITH WEAKER RIDGING EXTENDING ACROSS THE WESTERN LAKES. A LARGE AREA OF LOW PRESSURE IS EXPECTED TO DEVELOP OVER THE NORTHERN HIGH PLAINS MONDAY...DEEPENING AND SLOWLY MOVING EAST TOWARD THE LAKES THROUGH MID-WEEK. MODEST EAST-NORTHEAST WINDS NEAR THE SURFACE HIGH PRESSURE RIDGE WILL EVENTUALLY BECOME MORE EAST-SOUTHEAST AND INCREASE AS THE LOW APPROACHES TUESDAY NIGHT AND WEDNESDAY. FOR THE ILLINOIS AND INDIANA NEAR SHORE WATERS...SOUTH WINDS GUSTING 20-25 KT THIS MORNING ARE LIKELY PRODUCING WAVES OF 4+ FT NORTH OF DOWNTOWN CHICAGO. THEREFORE HAVE ISSUED A SMALL CRAFT ADVISORY FOR THAT PART OF THE IL SHORE THROUGH MID-MORNING. WINDS BECOMING SOUTHWEST WILL ALLOW WAVES TO SUBSIDE BELOW SMALL CRAFT ADVISORY CRITERIA AFTER THAT TIME. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 1149 AM CST Sat Nov 30 2013 .DISCUSSION... ISSUED 1057 AM CST Sat Nov 30 2013 High pressure sliding to the east this morning and southerly flow setting up over Central Illinois. Temperatures are warming up faster than the diurnal trend and have boosted highs a degree or two as well as adjusted the hourlys and the sky grids for more sunshine. Overall subtle adjustments, but will send out an update to cover the few changes. && .AVIATION... ISSUED 1105 AM CST Sat Nov 30 2013 High pressure sliding to the east giving way to increasing RH in the region resulting in a troublesome forecast for the overnight hours in ILX terminals. NAM has far more moisture trapped in the boundary layer and guidance resulting in everything from MVFR vis to LIFR cigs and vis. GFS in the same shape with less moisture and the HRRR is a little slower and more conservative but still moisture laden particularly NW of the Illinois River Valley. Trouble is, lower res models have increased moisture already in central MO, and sat imagery pointing to an overdone model run. That being said, dewpoints are on the increase with swrly flow. HRRR depiction of sfc RH a little more on track and def highlighting overnight NW of the IL river. Trouble is whether or not we are looking at stratus developing or vis drop. Not to mention that if enough moisture makes it into the SE and does not mix out this afternoon, chance for reduced vis in the SE as the skies clear out a bit tonight. For now, forecast conservative, but starting the trend for a visibility drop with majority rule to a cloud deck in the 4000 to 5000 ft range for PIA BMI and SPI this evening and through the overnight. HJS && .PREV DISCUSSION... ISSUED 227 AM CST Sat Nov 30 2013 Main forecast challenge focuses on departing storm system for the middle and end of next week...and whether or not it will produce any wintry precipitation across central Illinois. SHORT TERM...Today through Monday Mild and quiet weather will prevail through the short-term. Increasing southerly winds on the back-side of high pressure anchored along the East Coast will bring above normal temperatures back into the area today. Despite a chilly start to the day, the southerly flow coupled with ample afternoon sunshine will boost highs into the middle to upper 40s, with a few locations across the S/SW KILX CWA potentially reaching the 50 degree mark. A weak cold front will sag southward into the area on Sunday, bringing a few clouds and a shift in the winds. Thanks to northerly winds behind the boundary across the northern half of the CWA, temperatures will be a couple of degrees cooler than today. Front will become parallel to the zonal upper-level flow and will stall across the Ohio River Valley Sunday night into Monday. As Gulf moisture continues to flow northward over the boundary and a short-wave trough ripples eastward out of the Plains, a few light rain showers may develop on Monday. Several of the operational models are hinting at this, so have included a 20 POP accordingly. LONG TERM...Tuesday through Friday Main show will hold off until the extended, as an upper-level low currently over Alaska sinks southward and carves out a long-wave trough across the western CONUS by the middle of the week. Downstream ridging will produce deep southwesterly flow over the Midwest, resulting in cloudy skies and increasing precip chances Wednesday into Thursday. Model spread is still significant, so exact evolution of the developing storm system is uncertain at this time. General consensus develops surface low pressure in the lee of the Rockies, then tracks it northeastward into Canada by Thursday. Trailing cold front will likely push through Illinois Wednesday night into Thursday, triggering scattered showers and perhaps a thunderstorm. Things get tricky once the front passes and the colder air begins to arrive Thursday into Friday. 00z Nov 30 GFS/GEM both show front quickly advancing eastward, with precip largely ending before the cold airmass spreads into the area. This would tend to support a brief change-over to light snow Thursday night as the front slides eastward into Indiana before the precip comes to an end on Friday. Meanwhile, the 00z ECMWF suggests much more precip will hang back in the cold air Thursday night, followed by another wave of low pressure riding along the boundary and a renewed round of precip in the cold airmass on Friday. This could lead to a much more wintry scenario, with rain changing to snow Thursday night and another chance for snow on Friday. At this point, will trend toward the GFS/GEM consensus. As a result, will mention a rain/snow mix west of the Illinois River as early as Thursday, with rain changing to light snow further east to the Indiana border Thursday night. Will go with a mainly dry forecast for Friday, but will hold on to a chance for rain/snow across the far E/SE CWA in case secondary wave does indeed develop along departing front. Once this system exits the region, much colder weather will be on tap for the end of the week. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
228 PM EST SAT NOV 30 2013 .UPDATE... THE LONG TERM SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 328 AM EST SAT NOV 30 2013 AFTER A MAINLY SUNNY DAY...CLOUDS WILL INCREASE ACROSS THE OHIO VALLEY FOR THE SECOND HALF OF THE WEEKEND INTO EARLY NEXT WEEK AS A WEAK FRONT SLIDES INTO THE REGION. A FEW LIGHT RAIN SHOWERS OR SPRINKLES WILL BE POSSIBLE FROM SUNDAY AFTERNOON THROUGH MONDAY AS A COUPLE OF WEAK WAVE ALOFT MOVE ACROSS THE OHIO VALLEY. A MUCH BETTER CHANCE FOR RAIN WILL COME FOR THE SECOND HALF OF THE WEEK AS A STRONG COLD FRONT TRACKS THROUGH THE REGION. COLDER AIR WILL ONCE AGAIN RETURN BY THE END OF THE WEEK. && .NEAR TERM /REST OF TODAY/... ISSUED AT 954 AM EST SAT NOV 30 2013 UPDATE... SOME MID/HIGH CLOUDS WERE STILL ACROSS OUR FAR EAST...BUT HAVE CLEARED OUT ELSEWHERE. UPSTREAM SKIES WERE CLEAR AND WILL SCALE BACK CLOUD COVER A LITTLE WITH MOST AREAS BEING SUNNY THIS AFTERNOON. ONLY OTHER CHANGE WAS TO TWEAK TEMPERATURES UP A DEGREE SOME AREAS BASED ON 12Z RUC 2 METER TEMPERATURES...LOTS OF SUNSHINE AND WARM ADVECTION. ALL IN ALL THE CURRENT FORECAST IS ON TRACK. PREVIOUS NEAR TERM DISCUSSION FOLLOWS... MID AND HIGH LEVEL CLOUD COVER DRAPED ACROSS MUCH OF THE OHIO VALLEY EARLY THIS MORNING AS A WEAK WAVE ALOFT TRACKS ACROSS THE AREA. TEMPS WERE MAINLY IN THE 20S AT 08Z. BACK EDGE OF THE MORE SUBSTANTIAL HIGHER CLOUDS IS ALREADY EAST OF THE MISSISSIPPI RIVER EARLY THIS MORNING. EXPECT CLOUDS TO DIMINISH FROM WEST TO EAST ACROSS THE FORECAST AREA AROUND OR SHORTLY AFTER DAYBREAK...WITH SKIES THEN BECOMING MOSTLY SUNNY WITH ONLY PATCHY CIRRUS FOR THE REST OF THE DAY. WITH THE BROAD HIGH PRESSURE RIDGE NOW LOCATED EAST OF THE REGION...RETURN SOUTHERLY FLOW WILL DEVELOP AND INCREASE BY THIS AFTERNOON AS BOUNDARY LAYER FLOW STRENGTHENS AHEAD OF AN APPROACHING COLD FRONT. MODEL SOUNDINGS SUPPORT MAX GUSTS TO 20-25MPH BY THE AFTERNOON AS LOW LEVEL MIXING INCREASES. GUSTS WILL DROP OFF NEAR SUNSET AS THE NOCTURNAL INVERSION ESTABLISHES. TEMPS...SOUTHERLY FLOW AND WARM ADVECTION WILL BRING WARMER TEMPS INTO CENTRAL INDIANA FOR TODAY. MOS GUIDANCE MATCHES UP NICELY WITH LOW LEVEL THERMALS...WITH HIGHS TOPPING OUT NEAR LATE NOVEMBER NORMALS IN THE MID/UPPER 40S. && .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... ISSUED AT 328 AM EST SAT NOV 30 2013 FORECAST CHALLENGES FOCUS ON POTENTIAL FOR LIGHT PRECIP AS THE AFOREMENTIONED COLD FRONT DROPS INTO THE REGION...STALLS AND EVENTUALLY WASHES OUT. PREDOMINANT ZONAL FLOW IN THE UPPER LEVELS WILL BE PRESENT THROUGH THE PERIOD WITH SEVERAL WEAK WAVES ALOFT TRACKING QUICKLY THROUGH THE OHIO VALLEY. AT THE SURFACE...THE COLD FRONT WILL SLIDE SLOWLY SOUTH INTO THE REGION ON SUNDAY...EVENTUALLY STALLING OUT OVER SOUTHERN INDIANA SUNDAY NIGHT BEFORE WASHING OUT MONDAY. MOISTURE ACCOMPANYING THE FRONT WILL BE LIMITED...BUT MODEL SOUNDINGS AND RH PROGS CONTINUE TO SHOW IT IN GREATEST ABUNDANCE IN THE UPPER PORTIONS OF THE BOUNDARY LAYER BEGINNING EARLY SUNDAY...GRADUALLY LOWERING TO AROUND 2-3KFT INTO MONDAY AS AN INVERSION STEADILY STRENGTHENS. EXPECT CLOUDS TO EXPAND SOUTHEAST INTO THE FORECAST AREA AHEAD OF THE FRONT BEGINNING LATE TONIGHT AND CONTINUING INTO SUNDAY. WEAK ISENTROPIC LIFT AND A SUBTLE WAVE ALOFT MAY BE JUST ENOUGH TO GENERATE SOME LIGHT PRECIP SUNDAY AFTERNOON AND NIGHT...LIKELY IN THE FORM OF SPRINKLES...DRIZZLE OR VERY LIGHT RAIN SHOWERS. LOW LEVELS AND SURFACE TEMPS SHOULD REMAIN WARM ENOUGH TO SUPPORT PRECIP TYPE AS RAIN ONLY SUNDAY NIGHT. MODEL GUIDANCE LARGELY IN AGREEMENT ON BRINGING A SLIGHTLY STRONGER...BETTER PHASED UPPER WAVE ACROSS THE OHIO VALLEY ON MONDAY. WITH LOW LEVEL MOISTURE IN ABUNDANCE... THIS FEATURE SHOULD PRESENT A BETTER OPPORTUNITY FOR A FEW LIGHT RAIN SHOWERS. WILL CARRY JUST LOW CHANCE POPS HOWEVER AS ISENTROPIC LIFT REMAINS WEAK. MAJORITY OF THE MODEL GUIDANCE FAVORING THE PASSAGE OF THIS UPPER WAVE BY MONDAY EVENING...AND WILL END PRECIP CHANCES AS RIDGING ALOFT EXPANDS INTO THE OHIO VALLEY BY EARLY TUESDAY. TEMPS...CONSIDERING THE INCREASING CLOUDS AND POTENTIAL FOR WEAK COLD ADVECTION TO DEVELOP ON SUNDAY...METMOS TEMPS IN THE UPPER 40S/LOWER 50S LOOK RATHER AGGRESSIVE. HAVE TRENDED CLOSER TO /BUT NOT AS COLD AS/ THE MAVMOS FOR SUNDAY HIGHS. LEANED TOWARDS THE MAVMOS AGAIN FOR MONDAY WITH LIGHT RAIN/CLOUDS PRESENT. NEAR MAVMOS FOR LOWS TONIGHT...THEN TRENDED TOWARDS THE WARMER METMOS FOR SUNDAY NIGHT WITH EXPECTED CLOUD COVER. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... ISSUED AT 228 PM EST SAT NOV 30 2013 MODELS ARE CLOSE ENOUGH FOR THE MOST PART INTO THURSDAY...BUT DIFFER IN PRECIPITATION SIGNIFICANTLY ON FRIDAY. UNCERTAINTY IS HIGH SO GENERALLY STUCK CLOSE TO THE ALLBLEND INITIALIZATION FOR MOST ITEMS. THERE IS SOME UNCERTAINTY ON LIGHT RAIN DEVELOPMENT IN THE WARM ADVECTION PATTERN AHEAD OF THE ARCTIC FRONT TUESDAY NIGHT INTO WEDNESDAY. WITH ONLY LOW CHANCES FOR RAIN DECIDED TO KEEP CONTINUITY WITH PREVIOUS FORECAST AND GO DRY TUESDAY NIGHT AND SLIGHT CHANCE POPS FOR WEDNESDAY. CHANCES FOR RAIN THEN INCREASE INTO THURSDAY WITH LIKELY POPS THURSDAY AND THURSDAY NIGHT. ARCTIC FRONT SHOULD HAVE PLENTY OF MOISTURE TO WORK WITH DURING THIS PERIOD. QUESTIONS THEN ARISE FOR POPS ON FRIDAY. 00Z AND 12Z ECMWF KEEP PRECIPITATION ACROSS THE AREA AS A WAVE RIDES ALONG THE FRONT. GFS KEEPS WAVE FARTHER SOUTHEAST SO OUR AREA REMAINS DRY. SOME GFS ENSEMBLES ARE CLOSER TO THE ECMWF SOLUTION. 12Z CANADIAN WOULD APPEAR TO SUPPORT ECMWF AS WELL. THEREFORE KEPT HIGH CHANCE CATEGORY POPS FRIDAY WITH LOWER POPS FRIDAY NIGHT. THERMAL PROFILES INDICATE A MIX OF RAIN AND SNOW FRIDAY WITH SNOW FRIDAY NIGHT AS THE ARCTIC AIR MOVES IN. SATURDAY LOOKS TO BE VERY COLD AND DRY WITH ARCTIC HIGH MOVING IN. BEFORE THE ARCTIC FRONT ARRIVES THURSDAY EXPECT ABOVE NORMAL TEMPERATURES. && .AVIATION /DISCUSSION FOR THE 301800Z TAF ISSUANCE/... ISSUED AT 1159 AM EST SAT NOV 30 2013 VFR EXPECTED THROUGH THE PERIOD...ALTHOUGH CONFIDENCE LOWERS AFTER 12Z SUNDAY. WINDS COULD BRIEFLY GUST TO NEAR 15KT THIS AFTERNOON BUT MOST OF THE TIME WINDS WILL BE LESS THAN 10KT UNDER JUST SOME HIGH CLOUDS. LOW LEVEL MOISTURE INCREASES AHEAD OF A COLD FRONT TONIGHT SO ADDED A CEILING AROUND BKN060 AFTER 06Z. MODELS ARE TRYING TO HINT AT EVEN LOWER CEILINGS AFTER 12Z SUNDAY. CONFIDENCE IS NOT HIGH IN THIS SCENARIO...BUT ODDS ARE GETTING BETTER WITH EACH RUN. THEREFORE WILL LOWER CEILINGS TO LOW END OF VFR FOR NOW. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN/JH SHORT TERM...RYAN LONG TERM....50 AVIATION...50 VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1159 AM EST SAT NOV 30 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 328 AM EST SAT NOV 30 2013 AFTER A MAINLY SUNNY DAY...CLOUDS WILL INCREASE ACROSS THE OHIO VALLEY FOR THE SECOND HALF OF THE WEEKEND INTO EARLY NEXT WEEK AS A WEAK FRONT SLIDES INTO THE REGION. A FEW LIGHT RAIN SHOWERS OR SPRINKLES WILL BE POSSIBLE FROM SUNDAY AFTERNOON THROUGH MONDAY AS A COUPLE OF WEAK WAVE ALOFT MOVE ACROSS THE OHIO VALLEY. A MUCH BETTER CHANCE FOR RAIN WILL COME FOR THE SECOND HALF OF THE WEEK AS A STRONG COLD FRONT TRACKS THROUGH THE REGION. COLDER AIR WILL ONCE AGAIN RETURN BY THE END OF THE WEEK. && .NEAR TERM /REST OF TODAY/... ISSUED AT 954 AM EST SAT NOV 30 2013 UPDATE... SOME MID/HIGH CLOUDS WERE STILL ACROSS OUR FAR EAST...BUT HAVE CLEARED OUT ELSEWHERE. UPSTREAM SKIES WERE CLEAR AND WILL SCALE BACK CLOUD COVER A LITTLE WITH MOST AREAS BEING SUNNY THIS AFTERNOON. ONLY OTHER CHANGE WAS TO TWEAK TEMPERATURES UP A DEGREE SOME AREAS BASED ON 12Z RUC 2 METER TEMPERATURES...LOTS OF SUNSHINE AND WARM ADVECTION. ALL IN ALL THE CURRENT FORECAST IS ON TRACK. PREVIOUS NEAR TERM DISCUSSION FOLLOWS... MID AND HIGH LEVEL CLOUD COVER DRAPED ACROSS MUCH OF THE OHIO VALLEY EARLY THIS MORNING AS A WEAK WAVE ALOFT TRACKS ACROSS THE AREA. TEMPS WERE MAINLY IN THE 20S AT 08Z. BACK EDGE OF THE MORE SUBSTANTIAL HIGHER CLOUDS IS ALREADY EAST OF THE MISSISSIPPI RIVER EARLY THIS MORNING. EXPECT CLOUDS TO DIMINISH FROM WEST TO EAST ACROSS THE FORECAST AREA AROUND OR SHORTLY AFTER DAYBREAK...WITH SKIES THEN BECOMING MOSTLY SUNNY WITH ONLY PATCHY CIRRUS FOR THE REST OF THE DAY. WITH THE BROAD HIGH PRESSURE RIDGE NOW LOCATED EAST OF THE REGION...RETURN SOUTHERLY FLOW WILL DEVELOP AND INCREASE BY THIS AFTERNOON AS BOUNDARY LAYER FLOW STRENGTHENS AHEAD OF AN APPROACHING COLD FRONT. MODEL SOUNDINGS SUPPORT MAX GUSTS TO 20-25MPH BY THE AFTERNOON AS LOW LEVEL MIXING INCREASES. GUSTS WILL DROP OFF NEAR SUNSET AS THE NOCTURNAL INVERSION ESTABLISHES. TEMPS...SOUTHERLY FLOW AND WARM ADVECTION WILL BRING WARMER TEMPS INTO CENTRAL INDIANA FOR TODAY. MOS GUIDANCE MATCHES UP NICELY WITH LOW LEVEL THERMALS...WITH HIGHS TOPPING OUT NEAR LATE NOVEMBER NORMALS IN THE MID/UPPER 40S. && .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... ISSUED AT 328 AM EST SAT NOV 30 2013 FORECAST CHALLENGES FOCUS ON POTENTIAL FOR LIGHT PRECIP AS THE AFOREMENTIONED COLD FRONT DROPS INTO THE REGION...STALLS AND EVENTUALLY WASHES OUT. PREDOMINANT ZONAL FLOW IN THE UPPER LEVELS WILL BE PRESENT THROUGH THE PERIOD WITH SEVERAL WEAK WAVES ALOFT TRACKING QUICKLY THROUGH THE OHIO VALLEY. AT THE SURFACE...THE COLD FRONT WILL SLIDE SLOWLY SOUTH INTO THE REGION ON SUNDAY...EVENTUALLY STALLING OUT OVER SOUTHERN INDIANA SUNDAY NIGHT BEFORE WASHING OUT MONDAY. MOISTURE ACCOMPANYING THE FRONT WILL BE LIMITED...BUT MODEL SOUNDINGS AND RH PROGS CONTINUE TO SHOW IT IN GREATEST ABUNDANCE IN THE UPPER PORTIONS OF THE BOUNDARY LAYER BEGINNING EARLY SUNDAY...GRADUALLY LOWERING TO AROUND 2-3KFT INTO MONDAY AS AN INVERSION STEADILY STRENGTHENS. EXPECT CLOUDS TO EXPAND SOUTHEAST INTO THE FORECAST AREA AHEAD OF THE FRONT BEGINNING LATE TONIGHT AND CONTINUING INTO SUNDAY. WEAK ISENTROPIC LIFT AND A SUBTLE WAVE ALOFT MAY BE JUST ENOUGH TO GENERATE SOME LIGHT PRECIP SUNDAY AFTERNOON AND NIGHT...LIKELY IN THE FORM OF SPRINKLES...DRIZZLE OR VERY LIGHT RAIN SHOWERS. LOW LEVELS AND SURFACE TEMPS SHOULD REMAIN WARM ENOUGH TO SUPPORT PRECIP TYPE AS RAIN ONLY SUNDAY NIGHT. MODEL GUIDANCE LARGELY IN AGREEMENT ON BRINGING A SLIGHTLY STRONGER...BETTER PHASED UPPER WAVE ACROSS THE OHIO VALLEY ON MONDAY. WITH LOW LEVEL MOISTURE IN ABUNDANCE... THIS FEATURE SHOULD PRESENT A BETTER OPPORTUNITY FOR A FEW LIGHT RAIN SHOWERS. WILL CARRY JUST LOW CHANCE POPS HOWEVER AS ISENTROPIC LIFT REMAINS WEAK. MAJORITY OF THE MODEL GUIDANCE FAVORING THE PASSAGE OF THIS UPPER WAVE BY MONDAY EVENING...AND WILL END PRECIP CHANCES AS RIDGING ALOFT EXPANDS INTO THE OHIO VALLEY BY EARLY TUESDAY. TEMPS...CONSIDERING THE INCREASING CLOUDS AND POTENTIAL FOR WEAK COLD ADVECTION TO DEVELOP ON SUNDAY...METMOS TEMPS IN THE UPPER 40S/LOWER 50S LOOK RATHER AGGRESSIVE. HAVE TRENDED CLOSER TO /BUT NOT AS COLD AS/ THE MAVMOS FOR SUNDAY HIGHS. LEANED TOWARDS THE MAVMOS AGAIN FOR MONDAY WITH LIGHT RAIN/CLOUDS PRESENT. NEAR MAVMOS FOR LOWS TONIGHT...THEN TRENDED TOWARDS THE WARMER METMOS FOR SUNDAY NIGHT WITH EXPECTED CLOUD COVER. && .LONG TERM /TUESDAY THROUGH FRIDAY/... ISSUED AT 328 AM EST SAT NOV 30 2013 ENSEMBLES ARE IN GOOD AGREEMENT ON THE EVOLVING WEATHER PATTERN NEXT WEEK. UPPER RIDGING EXPECTED TO DEVELOP ALONG THE EAST COAST AS A TROUGH SETS UP FROM THE NORTHERN MIDWEST BACK INTO THE SOUTHERN ROCKIES. THIS WILL RESULT IN SOUTHWESTERLY UPPER FLOW LOCALLY. APPEARS A DECENT CHUNK OF ENERGY WILL EJECT OUT OF THE WESTERN TROUGH INTO WESTERN GREAT LAKES AROUND NEXT THURSDAY. WILL KEEP POPS IN THE FORECAST FOR RAIN ON WEDNESDAY AND ESPECIALLY THURSDAY AS THE UPPER DISTURBANCE MOVES THROUGH. SEVERAL ENSEMBLES SUGGEST MORE ENERGY MAY EJECT OUT ACROSS THE OHIO OR TENNESSEE VALLEY AROUND NEXT FRIDAY...WHICH MAY INDUCE A SURFACE WAVE ON THE PRIMARY COLD FRONT. WILL GO WITH CHANCE POPS FOR RAIN OR SNOW AT THAT TIME. AT THIS POINT...THE ENSEMBLES INDICATE ANY SNOW ACCUMULATIONS LATE NEXT WEEK WILL BE MINOR. && .AVIATION /DISCUSSION FOR THE 301800Z TAF ISSUANCE/... ISSUED AT 1159 AM EST SAT NOV 30 2013 VFR EXPECTED THROUGH THE PERIOD...ALTHOUGH CONFIDENCE LOWERS AFTER 12Z SUNDAY. WINDS COULD BRIEFLY GUST TO NEAR 15KT THIS AFTERNOON BUT MOST OF THE TIME WINDS WILL BE LESS THAN 10KT UNDER JUST SOME HIGH CLOUDS. LOW LEVEL MOISTURE INCREASES AHEAD OF A COLD FRONT TONIGHT SO ADDED A CEILING AROUND BKN060 AFTER 06Z. MODELS ARE TRYING TO HINT AT EVEN LOWER CEILINGS AFTER 12Z SUNDAY. CONFIDENCE IS NOT HIGH IN THIS SCENARIO...BUT ODDS ARE GETTING BETTER WITH EACH RUN. THEREFORE WILL LOWER CEILINGS TO LOW END OF VFR FOR NOW. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN/JH SHORT TERM...RYAN LONG TERM....JAS AVIATION...50 VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
1136 AM MST SAT NOV 30 2013 .UPDATE... LOW CLOUDS AND AREAS OF FOG ARE HANGING TOUGH ACROSS THE FOUR CORNERS REGION. MODELS GENERALLY DO NOT HAVE A GOOD HANDLE ON WHEN THE INVERSION WILL BREAK...BUT RUC SEEMS TO HAVE THE BETTER GRASP OF ANY. INCREASED CLOUD COVER FOR THE AREA THROUGH THE AFTERNOON...AND WITH THE EXPECTED CLOUD COVER...HAVE LOWERED TEMPS A FEW DEGREES...ESPECIALLY FOR KFMN. UPDATES OUT SHORTLY. 34 && .PREV DISCUSSION...1109 AM MST SAT NOV 30 2013... .AVIATION... 18Z TAF CYCLE HIGH CIRRUS CLOUDS WILL STICK AROUND OVER THE SOUTHERN HALF TO TWO THIRDS OF THE FORECAST AREA THROUGH THE NEXT 24 HOURS. LATEST SATELLITE AND OBSERVATIONS SHOW SLOWLY IMPROVING CONDITIONS AT GUP/FMN. THIS TREND SHOULD CONTINUE BUT THE MODELS HAVE HAD A HARD TIME PREDICTING THE LIFR/IFR AND MVFR CONDTIONS. THESE CONDITIONS SHOULD RETURN WITH ABUNDANT LOW LVL MOISTURE AND A STABLE INVERSION TONIGHT. QUESTION IS WHEN. THINKING SLIGHTLY EARLIER THAN LAST NIGHT AND THIS IS REFLECTED IN THE LATEST TERMINAL FORECASTS AT GUP/FMN. 50 .PREV DISCUSSION...318 AM MST SAT NOV 30 2013... LATEST GOES IMAGER FOG PRODUCT PICKING UP ON AN AREA OF FOG ACROSS THE NORTHWEST PLATEAU...WEST OF THE DIVIDE TO NEAR GALLUP. ONE QUARTER MILE VISIBILITY IN FREEZING FOG IN THE LATEST KFMN AND KGUP OBS...LIKELY TO PERSIST BEYOND SUNRISE FOR A COUPLE OF HOURS. STREAM OF PACIFIC MOISTURE RESULTING IN AN ELONGATED AREA OF DENSE HIGH CLOUDS FROM THE EASTERN PACIFIC OCEAN...NORTHEAST ACROSS NW MEXICO...SOUTHERN AZ AND NM MAKING FOR A TRICKY HIGH TEMPERATURE FORECAST TODAY. THE UPPER FLOW TO BECOME MORE WESTERLY OVER THE NEXT 24-36HRS...WHICH WILL CAUSE THE PACIFIC MOISTURE TAP TO SHIFT SOUTH AND EAST OF OUR FORECAST AREA. HOWEVER...HIGH CLOUDS WILL HANG AROUND AND MOVE ACROSS NM FROM THE NORTHWEST GOING INTO MONDAY. BREEZY TO LOCALLY WINDY CONDITIONS FORECAST AS NW FLOW INCREASES SUNDAY INTO MONDAY...WITH THE EAST SLOPES OF THE CENTRAL MOUNTAIN CHAIN...ADJACENT HIGHLANDS AND PORTIONS OF THE EAST CENTRAL PLAINS FAVORED FOR STRONGER WINDS. WINDS ALOFT BACK FROM NW TO WSW TUESDAY INTO WEDNESDAY IN ADVANCE OF A POTENT UPPER LEVEL TROUGH. TEMPS WILL TREND UP IN ADVANCE OF THIS ANOMALOUSLY COLD SYNOPTIC WEATHER FEATURE AND WILL BE ABOVE TO WELL ABOVE NORMAL TUESDAY AND TUESDAY NIGHT. A DEEPENING LEE SIDE TROUGH WILL BE PARTIALLY RESPONSIBLE FOR INCREASING WINDS... ESPECIALLY ACROSS THE NORTHEAST PLAINS AND HIGHLANDS. TEMPS BEGIN A DOWNWARD TREND WEDNESDAY AS CLOUDS AND CHANCES FOR PRECIPITATION TREND UP. A STRONG COLD FRONT TO MOVE EAST ACROSS THE AREA LATE WEDNESDAY INTO THURSDAY...WITH A BACKDOOR PUSH DOWN THE EASTERN PLAINS. WINDY CONDITIONS ARE FORECAST WEDNESDAY IN ADVANCE OF AND IMMEDIATELY BEHIND THE COLD FRONT...MAY EVENT HIT WIND ADVISORY THRESHOLDS IN A FEW SPOTS. PRECIP CHANCES LOOK TO FAVOR THE NORTHERN AND WESTERN MOUNTAINS...ESPECIALLY WEDNESDAY AS THE FRONT PUSHES THROUGH. SNOW ACCUMULATION MAY BE SIGNIFICANT ENOUGH TO WARRANT ADVISORIES ACROSS THE NORTHERN MOUNTAINS. BOTH THE LATEST ECMWF AND GFS SHOW THE UPPER LEVEL TROUGH AXIS PUSHING THROUGH THURSDAY NIGHT INTO FRIDAY. THIS AIRMASS WILL LIKELY BE THE COLDEST SO FAR THIS SEASON WITH THE LATEST MEDIUM RANGE MODELS SHOWING NEAR -20C AT 700MB ALONG THE NM/CO BORDER BY 12Z FRIDAY. THE BIG WEATHER STORY FROM LATE THURSDAY THROUGH INTO SATURDAY WILL DEFINITELY BE THE WELL BELOW NORMAL TEMPERATURES. 11 .FIRE WEATHER... A FEW MORE DAYS OF POOR VENTILATION WILL PLAGUE NORTHERN AND CENTRAL NEW MEXICO BEFORE THE PATTERN SHIFTS TO A WINDIER ONE. A CUT OFF LOW WILL STAY OVER THE EASTERN PACIFIC WATERS WITH HIGH LEVEL MOISTURE STREAMING INTO NEW MEXICO TODAY. TEMPERATURES SHOULD STILL REACH SEASONABLE AVERAGES FOR LATE NOVEMBER. LEE SIDE SURFACE TROUGH WILL LOSE SOME STRENGTH BY AFTERNOON...AND THUS AFTERNOON BREEZES WILL BE MODERATED IN EASTERN PARTS OF THE STATE TODAY. THESE LIGHT WINDS AND STEEP INVERSIONS WILL PRODUCE THE POOR MIXING AND INEFFICIENT DISPERSION. MINIMUM HUMIDITY WILL FALL TO 25 TO 45 PERCENT ACROSS THE FORECAST AREA...RECOVERING TO 60 TO 80 PERCENT IN MOST OF THE EASTERN PLAINS TONIGHT AND UP TO 80 TO 100 PERCENT IN THE WEST THROUGH SUNDAY MORNING. AS FLOW ALOFT TURNS MORE NORTHWESTERLY...A WEAK DISTURBANCE ALOFT WILL SLIDE DOWN TOWARD NM TONIGHT AND SUNDAY...BUT THIS FEATURE SHOULD POSE LITTLE ALTERATIONS TO THE OVERALL WEATHER ELEMENTS. WHILE THE WINDS ALOFT WILL STRENGTHEN SOME SUNDAY AND MONDAY...MIXING AND VENTILATION WILL STILL REMAIN POOR. LITTLE TEMPERATURE VARIATION WILL ALSO BE NOTICED SUNDAY AND MONDAY. BY TUESDAY FLOW ALOFT WILL BEGIN SHIFTING MORE SOUTHWESTERLY OVER NM AS A TROUGH DEEPENS OVER THE WESTERN STATES. WINDS WILL INCREASE SIGNIFICANTLY...ENOUGH TO IMPROVE VENTILATION BUT ALSO POTENTIALLY INTRODUCING SOME NEAR-CRITICAL WINDS. AT THIS TIME FORECAST WIND SPEEDS ARE BELOW CRITICAL CRITERIA...DUE TO SOME MODEL DISCREPANCIES ON THE PLACEMENT OF THE LEE-SIDE SURFACE LOW. SHOULD MODELS CONVERGE ON A MORE FAVORABLE PLACEMENT OF THIS FEATURE...WINDS MAY NEED TO BE INCREASED. TEMPERATURES ARE EXPECTED TO STILL BE FAIRLY WARM ON TUESDAY...ESPECIALLY IN THE EAST WITH DOWNSLOPING. HOWEVER...RH FORECAST AT THIS TIME IS RESTING JUST ABOVE CRITICAL THRESHOLDS. COOLER CONDITIONS AND BATCHES OF PRECIPITATION WILL BE SPREADING INTO NM WEDNESDAY THROUGH THE END OF THE WORK WEEK AS THE BASE OF THE AFOREMENTIONED TROUGH SWINGS THROUGH. WINDS WILL BE ELEVATED THROUGH THIS PERIOD WITH BETTER VENTILATION...BUT NO CRITICAL CONDITIONS ARE EXPECTED AS OF RIGHT NOW. 52 .AVIATION... 06Z TAF CYCLE HIGH CLOUDS STREAMING NEWD AHEAD OF UPR LOW OFF SOCAL AND OVR NM. SFC LEE TROF THRU 30/12Z THEN WK WND SHIFT EXPECTED IN THE ERN PLNS AS SFC LOW SAGS SWD TO VCNTY KCVS. POTENTIAL FOR MVFR/IFR CIGS/VSBYS FOUR CORNERS/KGUP REGION IN BR/FZFG PRIOR TO 15Z. && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 34
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1248 PM EST SAT NOV 30 2013 .SYNOPSIS... HIGH PRESSURE WILL EXTEND SOUTHWEST INTO THE REGION THROUGH TONIGHT...THEN WEAKEN ON SUNDAY. A LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP ALONG THE CAROLINA COAST ON MONDAY AS AN UPPER LEVEL DISTURBANCE APPROACHES FROM THE WEST. && .NEAR TERM /THROUGH TODAY/... AS OF 1050 AM SATURDAY... SURFACE HIGH AS OF 15Z IS CENTERED WELL TO THE NORTHEAST...OVER NEW ENGLAND AND INTO MAINE...WITH THE RIDGE AXIS EXTENDING SOUTHWEST INTO NC...MAINLY ALONG THE WESTERN PORTION OF THE AREA. THE PRESSURE GRADIENT WILL RELAX SOME AS THE HIGH MOVES OFF THE NE COAST AND THE RIDGE WEAKENS...THUS ALLOWING THE WINDS TO RELAX SOME AS WELL. THE RETURN FLOW WILL BECOME MORE NORTHEASTERLY AS THAT HAPPENS... ALLOWING FOR WARMER TEMPS ACROSS THE SOUTH AND EAST AND COOLER IN THE NW. THE 12Z UPPER AIR ANALYSES SHOW THE TROUGH... MORE PROMINENT AT 700 AND 850 MB...EXTENDING FROM THE WESTERN GREAT LAKES SW INTO OK/TX...WITH HIGH PRESSURE/RIDGING OVER THE EASTERN US. AN UPPER LEVEL WAVE JUST WEST OF THE APPALACHIANS...SHOWN IN BOTH SATELLITE IMAGERY AND INDICATED BY MODEL GENERATED VORTICITY PLOTS...IS GENERATING AN AREA OF CLOUDS OVER WV/VA...WHICH MAY EXTEND INTO THE NORTHERN AND WESTERN PORTIONS OF THE AREA TODAY...ALTHOUGH THE GREATEST COVERAGE WILL BE OVER VA. WITH THE STRONG WESTERLY FLOW ALOFT EXPECTED TO CONTINUE TODAY AS THE UPPER LEVEL RIDGE CONTINUES TO BUILD...SUBSIDENCE SHOULD BE STRONG ENOUGH TO LIMIT MIXING IN THE LOW LEVELS...WHICH IN COMBINATION WITH THE INCREASING CLOUD COVER... SHOULD BE ENOUGH TO YIELD HIGHS TODAY A BIT COOLER THAN YESTERDAY... MAINLY IN THE MID 40S TO LOW 50S. -KC THE LATEST RAP...ALONG WITH THE HRRR WRF...FORECAST AN INCREASE IN LOW-LEVEL MOISTURE FROM THE SOUTHEAST LATE IN THE DAY. THIS MAY BE REASONABLE...AS THE SATELLITE FOG PRODUCT SHOWED AREAS OF LOW CLOUDS JUST OFFSHORE FROM SOUTHEAST NORTH CAROLINA EARLY THIS MORNING. HAVE ADDED SOME CLOUD COVER TO THE FORECAST PARTICULARLY TOWARD THE SOUTH AND EAST DURING THE AFTERNOON. -DJF && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... AS OF 650 AM SATURDAY... SURFACE HIGH PRESSURE SHOULD BE DIRECTLY OVERHEAD OVERNIGHT KEEPING THE GRADIENT VERY RELAXED. THE POTENTIAL FOR A QUITE CHILLY NIGHT WOULD EXIST BUT THE COMBINATION OF SOME HIGH CLOUDS AND THE GFS FORECAST OF INCREASING 850MB MOISTURE FROM THE SOUTH AND SOUTHWEST MAY ACT TO KEEP TEMPERATURES CLOSE TO THE GUIDANCE LOWS OVERNIGHT. THE LATEST SATELLITE FOG PRODUCT SHOWS LOW-LEVEL MOISTURE MOVING WEST TOWARD THE SOUTH CAROLINA COAST...AND LOW-LEVEL ISENTROPIC FORECASTS ALONG WITH THE INCREASING 850MB MOISTURE SUPPORT AN INCREASE IN CLOUD COVER TO PARTLY-TO-MOSTLY CLOUDY PARTICULARLY ALONG AND SOUTH OF ABOUT INTERSTATE 85 DURING THE OVERNIGHT HOURS. THE TIMING OF THIS IS...OF COURSE...CRITICAL TO THE OVERNIGHT TEMPERATURE FORECAST...BUT FOR THIS FORECAST WILL LEAN TOWARD THE COOLER MOS GUIDANCE IN THE TRIAD AND THE WARMER MOS GUIDANCE ELSEWHERE. K INDICES SLOWLY RISE SUNDAY...WITH PRECIPITABLE WATER VALUES RISING LATE SUNDAY TO BETWEEN 0.75 AND ONE INCH...ABOVE NORMAL FOR VERY EARLY DECEMBER AT ABOUT THE 75TH PERCENTILE. LIFT STARTS TO INCREASE LATE SUNDAY AND PARTICULARLY SUNDAY NIGHT AS ISENTROPIC LIFT ON THE 300K SURFACE INCREASES...WITH THE BEST POTENTIAL VORTICITY ON THE 1.5PVU SURFACE FORECAST BY THE GFS ALONG AND SOUTH OF ABOUT U.S. 64 LATE SUNDAY THROUGH SUNDAY NIGHT. SURFACE DEPICTIONS OF THE NAM AND GFS DIFFER AND ARE FAIRLY CONSISTENT WITH THEMSELVES OVER THE LAST TWO OR THREE RUNS...WITH THE NAM SHOWING A WEAK SURFACE LOW JUST OFF THE SOUTH CAROLINA COAST SUNDAY NIGHT WHILE THE GFS FORECASTS MORE OF AN INVERTED TROUGH BEFORE SURFACE LOW PRESSURE STRENGTHENS OFFSHORE. REGARDLESS...QPF AND MOS GUIDANCE POPS ARE SIMILAR... KEEPING MOST CHANCES FOR PRECIPITATION AT BAY SUNDAY AND INCREASING CHANCES OVER MOST OF CENTRAL NORTH CAROLINA SUNDAY NIGHT. WILL NOTE A SLIGHT CHANCE OF RAIN MAINLY OVER THE SANDHILLS AND SOUTHERN COASTAL PLAIN SUNDAY WHERE THE BEST LOW-LEVEL MOISTURE SHOULD RESIDE AS POTENTIAL VORTICITY INCREASES...WITH A CHANCE OF RAIN SUNDAY NIGHT MAINLY ALONG AND EAST OF A LINE FROM ABOUT KIXA TO KAFP WITH A SLIGHT CHANCE NORTH OF THAT LINE. DEBATED WHETHER OR NOT TO INCLUDE A SLIGHT CHANCE IN THE TRIAD AND FOR THIS FORECAST WILL SHOW A VERY LOW SLIGHT CHANCE THERE OVERNIGHT SUNDAY...THOUGH THIS COULD END UP BEING OVERDONE WITH SUFFICIENT MOISTURE AND LIFT REMAINING JUST EAST. SURFACE WET BULB TEMPERATURES AND PARTIAL THICKNESSES SUPPORT ALL LIQUID. ONCE AGAIN 1000-850MB THICKNESSES WOULD SUPPORT HIGHS SUNDAY ABOVE MOS GUIDANCE...BUT GIVEN THE EXPECTED CLOUD COVER...WILL FORECAST HIGHS AS A BLEND OF MAV AND MET MOS GUIDANCE FOR A FAIRLY UNIFORM LOWER 50S IN MOST LOCATIONS. OVERNIGHT SUNDAY...IF IT REMAINS DRY IN THE TRIAD LOWS SHOULD BE NEAR THE WARMER GUIDANCE...WHILE WHERE IT RAINS TEMPERATURES WOULD APPROACH THE DEW POINT. THIS COINCIDES WITH A BLEND OF MOS GUIDANCE...ALTHOUGH HIGHER THAN GUIDANCE TOWARD KRWI...FOR LOWS IN THE MID TO UPPER 30S NORTHWEST...TO MID 40S TOWARD KCTZ. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 235 AM SATURDAY... ON MONDAY A LOW AMPLITUDE NORTHERN STREAM SHORTWAVE DROPS INTO THE THE DEEP SOUTH AS A SHEARING SOUTHERN STREAM SYSTEM WITH A 250MB JET OF 140 KTS PHASE TOGETHER BEFORE THE TROUGH AXIS MOVES OFF THE SOUTHEAST COAST MONDAY NIGHT. THE TROUGH BECOMES NEGATIVELY TILTED AND INITIATES SURFACE CYCLOGENESIS MONDAY NIGHT AND TUESDAY. RECENT NWP TRENDS HAVE SUGGESTED A LESS AMPLIFIED SYSTEM WHILE PRODUCING A BIT MORE QPF ACROSS MAINLY SOUTHEASTERN NC. IT REMAINS DIFFICULT AND CONFIDENCE IS LOW REGARDING HOW FAR NORTH AND WEST PRECIPITATION WILL SPREAD ACROSS CENTRAL NC BUT CONFIDENCE IS GROWING THAT SOME LIGHT PRECIPITATION WILL FALL ACROSS THE SOUTHERN COASTAL PLAIN AND SANDHILLS REGION. NWP CONSENSUS SHOWS THE DEEPEST MOISTURE AND STRONGEST FORCING WILL BE CONFINED TO SOUTHEASTERN PORTIONS OF THE RAH CWA WITH RAPIDLY DECREASING RAIN CHANCES ACROSS THE NORTHERN AND WESTERN PIEDMONT. ISENTROPIC ANALYSIS DEPICTS THE PATTERN WELL WITH A FAIRLY NARROW CORRIDOR OF LIFT/SATURATION THAT SLIDES MAINLY ACROSS SOUTHERN AND EASTERN NC. PRECIPITATION CHANCES QUICKLY TAIL OFF FROM WEST TO EAST ON MONDAY NIGHT. THE AIR MASS AHEAD OF THE SYSTEM WILL HAVE MODIFIED AND THE PRECIPITATION WILL FALL AS RAIN. GIVEN THE MODIFICATION OF THE AIR MASS AND THE LIGHT PRECIPITATION CHANCES...DO NOT EXPECT A SIGNIFICANT CAD EVENT TO OCCUR. HIGHS MONDAY WILL RANGE IN THE 49-56 RANGE WITH MAX TEMPERATURES DEPENDENT ON THE LOCATION AND INTENSITY OF THE PRECIPITATION. AFTER THE UPPER TROUGH AXIS MOVES OFFSHORE...THE FLOW ALOFT BECOMES MORE NORTHWESTERLY. ANOTHER DISTURBANCE IN THE FLOW AND SOME RESIDUAL MOISTURE SHOULD BE SUFFICIENT TO PRODUCE SOME CLOUDINESS ON TUESDAY BUT OTHERWISE FAIR CONDITIONS ARE EXPECTED WITH HIGHS IN THE LOWER TO MID 50S. THE FLOW FLATTENS ON TUESDAY NIGHT AND HEIGHTS RISE ON WEDNESDAY INTO THURSDAY WITH INCREASING HIGH CLOUDS LATE WEDNESDAY AND A FAIR AMOUNT OF CLOUDS EXPECTED ON THURSDAY. EXPECT DRY WEATHER THROUGH AT LEAST THURSDAY AFTERNOON AS THE RIDGE AXIS BUILDS OVERHEAD. MODERATING TEMPERATURES ARE EXPECTED ON THURSDAY INTO FRIDAY WITH HIGHS IN THE MID TO UPPER 50S ON WEDNESDAY WARMING INTO THE UPPER 50S TO LOWER 60S ON THURSDAY WITH MORNING LOWS IN THE MID 30S TO AROUND 40. A LONGWAVE TROUGH DEVELOPS OVER THE WESTERN U.S. LATE THURSDAY INTO FRIDAY AS AN ARCTIC AIRMASS DROPS INTO THE NORTHERN ROCKIES AND NORTHERN PLAINS. AN INCREASINGLY MOIST SOUTHERLY TO SOUTHWESTERLY FLOW DEVELOPS ACROSS THE CENTRAL U.S. AS THE TROUGH PUSHES EAST ON FRIDAY. THE ASSOCIATED COLD FRONT REACHES THE WESTERN APPALACHIANS ON FRIDAY MORNING. THERE ARE TIMING DIFFERENCES AMONG THE GUIDANCE REGARDING THE EASTWARD ADVANCEMENT OF THE FRONT AND THE ASSOCIATED PRECIPITATION WITH WPC PREFERRING A GEFS MEAN AND EC ENS MEAN. REGARDLESS...THE THREAT OF RAIN WILL ARRIVE WITH LOW PROBABILITIES IN THE WEST LATE THURSDAY NIGHT. POPS WILL INCREASE FROM WEST TO EAST FRIDAY AND FRIDAY NIGHT WITH THE BEST CHANCE OF RAIN AT THIS POINT APPEARING TO BE FRIDAY NIGHT AND SATURDAY. AHEAD OF THE FRONT AND THE RAIN...TEMPERATURES ARE LIKELY TO CLIMB INTO THE 60S FRIDAY AFTERNOON. -BLAES && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 1245 PM SATURDAY... 24 HOUR TAF PERIOD: HIGH CONFIDENCE OF CONTINUED VFR CONDITIONS THROUGH THIS AFTERNOON AND EVENING WITH THE RIDGE EXTENDING INTO NC AND LIGHT NW WINDS. STILL EXPECT AN INCREASE IN LOW LEVEL MOISTURE ACROSS THE COASTAL PLAIN OVERNIGHT AND INTO SUNDAY MORNING... WHICH COULD YIELD A PERIOD OF SUB-VFR CONDITIONS...MAINLY AT KFAY...AND POSSIBLY AT KRWI (LESS LIKELY TOWARD KRDU) AND POINTS ALONG AND SOUTHEAST OF THERE. ALTHOUGH THE WINDS WILL BE LIGHT...THEY WILL BE SLOWLY BACKING FROM PREDOMINANTLY NORTH AND NORTHEAST TO WEST AND NORTHWEST BY THE END OF THE TAF PERIOD. LOOKING AHEAD: EXPECT MOISTURE ADVECTION INTO THE AREA SUNDAY NIGHT TO LEAD TO INCREASING CLOUD COVER AND THE CHANCE FOR RAIN. THERE IS A GOOD CHANCE FOR SUB-VFR CONDITIONS DURING THIS TIME. EXPECT THE ATMOSPHERE TO DRY FROM THE TOP DOWN ON TUESDAY...LIKELY IMPROVING AVIATION CONDITIONS TO VFR FOR THE REMAINDER OF TUESDAY AND INTO WEDNESDAY. SUB-VFR CONDITIONS ARE POSSIBLE AGAIN WEDNESDAY NIGHT INTO THURSDAY AS SOUTHERLY FLOW ADVECTS MOISTURE INTO CENTRAL NC. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE && $$ SYNOPSIS...VINCENT NEAR TERM...KC/DJF SHORT TERM...DJF LONG TERM...BLAES AVIATION...KC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
253 PM CST SAT NOV 30 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 252 PM CST SAT NOV 30 2013 THE MAIN FORECAST CONCERNS IN THE SHORT TERM WILL BE PRECIPITATION CHANCES LATE TONIGHT INTO SUNDAY. THERE IS GENERAL AGREEMENT AMONG THE SHORT TERM MODELS THAT ANOTHER UPPER WAVE WILL MOVE ACROSS THE NORTHERN PLAINS TONIGHT INTO SUNDAY AS AN H3 JET APPROACHES THE REGION. THERE ARE SOME DIFFERENCES IN TIMING...BUT MOST SOLUTIONS KEEP THE PRECIPITATION CHANCES WEST OF THE FORECAST AREA UNTIL LATE TONIGHT. WILL SHOW INCREASING POPS IN THE WEST AFTER MIDNIGHT...AND THEN SPREAD THE HIGHER POPS ACROSS WESTERN AND CENTRAL NORTH DAKOTA ON SUNDAY. PRECIPITATION TYPE WILL BE A CHALLENGE WITH THERMAL PROFILES SUGGESTING MAINLY SNOW IN THE NORTH AND EAST...HOWEVER WARMER AIR IS EXPECTED TO BE IN PLACE IN THE SOUTH AND WEST. HAVE GONE WITH A MIX OF PRECIPITATION TYPES IN THE WEST CENTRAL AND SOUTHWEST LATE TONIGHT AND SUNDAY. KEPT MOST SNOW AMOUNTS AN INCH OR LESS...AND DID NOT CARRY ANY ICE ACCUMULATIONS DUE TO THE UNCERTAINTY STILL SURROUNDING THE THERMAL PROFILES. LATER SHIFTS WILL HAVE TO KEEP AN EYE ON HOW THINGS PROGRESS...BUT DO NOT HAVE ENOUGH CONFIDENCE IN THE MIXED PRECIPITATION ACCUMULATING ENOUGH TONIGHT / SUNDAY TO WARRANT THE ISSUANCE OF ANY ADVISORIES AT THE MOMENT. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 252 PM CST SAT NOV 30 2013 THE HIGHLIGHT OF THE EXTENDED FORECAST IS A POTENTIAL PROLONGED SNOW EVENT MONDAY THROUGH WEDNESDAY...FOLLOWED BY VERY COLD ARCTIC AIR. THE 12 UTC DETERMINISTIC GUIDANCE IS IN GOOD AGREEMENT ON SURFACE CYCLOGENESIS ACROSS SOUTHEAST ALBERTA AND INTO CENTRAL MONTANA SUNDAY NIGHT INTO MONDAY. IN RESPONSE...A BAND OF PREICPITATION IN LOW LEVEL ISENTROPIC LIFT IS FORECAST TO DEVELOP ACROSS NORTHWEST AND INTO CENTRAL NORTH DAKOTA. PRECIPITATION IS EXPECTED TO BE ALL SNOW ACROSS NORTHERN NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY. HOWEVER...A MIX OF FREEZING RAIN AND SLEET IS POSSIBLE ON THE WESTERN PERIPHERY OF THE BAND...ESPECIALLY DURING THE MORNING...WHERE A +1 TO +3 C MELTING LAYER ALOFT WILL BE IN PLACE. A WINTER WEATHER ADVISORY MAY BE NEEDED FOR THIS EVENT AS TWO TO FOUR INCHES OF SNOW ARE POSSIBLE ALONG AND NORTH OF US HIGHWAY 2 AND INTO THE JAMES RIVER VALLEY...WITH POSSIBLE MINOR ICE ACCUMULATIONS ACROSS THE SOUTH CENTRAL. FOR THE MONDAY NIGHT THROUGH WEDNESDAY PORTION OF THE STORM...THE 12 UTC GFS/NAM AND 15 UTC SREF WERE DISCOUNTED AS THEY EJECT A DEEP AND RAPIDLY PROPAGATING UPPER LEVEL LOW OUT OF THE MAIN LONGWAVE. THIS IS MUCH DIFFERENT AND A SIGNIFICANT CHANGE FROM THE PREFERRED 12 UTC ECMWF AND GEM SOLUTIONS. FOLLOWING THESE SOLUTIONS...A PROLONGED PERIOD OF LIGHT TO MODERATE SNOW IS EXPECTED FROM MONDAY NIGHT THROUGH WEDNESDAY ACROSS OF WESTERN AND CENTRAL NORTH DAKOTA WITH A DEEP FETCH OF SOUTHWEST FLOW ALOFT. HEAVY SNOWFALL ACCUMULATIONS ARE POSSIBLE...WITH BLOWING SNOW BECOMING A THREAT WEDNESDAY ON THE BACKSIDE OF THE SURFACE LOW. THEREAFTER...VERY COLD ARCTIC AIR TAKES OVER THE REGION INTO THE WEEKEND. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 252 PM CST SAT NOV 30 2013 AFTERNOON VISIBLE SATELLITE IMAGERY SHOW STRATUS ACROSS PARTS OF SOUTHERN CANADA MOVING SOUTH TOWARDS NORTHERN NORTH DAKOTA. THE LATEST RAP MODEL SUGGESTS THE STRATUS COULD REACH KMOT AND BY LATE AFTERNOON...AND THEN CONTINUE TO SPREAD SOUTH TONIGHT. LOWER CLOUDS ARE ALSO POSSIBLE AS A CHANCE OF PRECIPITATION MOVES TOWARDS THE REGION LATE TONIGHT INTO SUNDAY. OVERALL...WILL SHOW A DOWNWARD TREND IN REGARDS TO CEILINGS...WITH VISIBILITY RESTRICTIONS POSSIBLE AS PRECIPITATION CHANCES INCREASE. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...CK LONG TERM...AYD AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1258 PM CST SAT NOV 30 2013 .UPDATE... ISSUED AT 1258 PM CST SAT NOV 30 2013 WEAK RADAR RETURNS CONTINUE ACROSS PARTS OF WEST AND SOUTH CENTRAL NORTH DAKOTA EARLY THIS AFTERNOON. THE LATEST RAP STILL SHOWS LIGHT PRECIPITATION ACROSS THE FAR SOUTHWEST FOR ANOTHER COUPLE HOURS...SO WILL MAINTAIN A SLIGHT CHANCE POP IN THAT AREA. BAKER MONTANA REPORTED LIGHT RAIN IN THE PAST HOUR...AND WITH SURFACE TEMPERATURES ACROSS THE SOUTHWEST NOW IN THE MID 30S...THE PREVAILING PRECIPITATION TYPE SHOULD BE RAIN. UPDATE ISSUED AT 959 AM CST SAT NOV 30 2013 A WEAK UPPER WAVE WILL CONTINUE TO MOVE ACROSS WESTERN / SOUTHERN NORTH DAKOTA TODAY. AREA RADARS SHOW WEAK RETURNS ACROSS WESTERN AND CENTRAL NORTH DAKOTA...HOWEVER DRY AIR AS SHOWN IN THE 12Z BISMARCK SOUNDING HAS PREVENTED MOST OF THE PRECIPITATION FROM REACHING THE GROUND. THE 30.12Z NAM STILL SUGGESTS THERE COULD BE LIGHT PRECIPITATION IN THE SOUTHWEST INTO EARLY AFTERNOON...SO WILL KEEP A SLIGHT CHANCE POP IN THAT AREA. PRECIPITATION TYPE IS ALSO A CHALLENGE WITH THERMAL PROFILES SUGGESTING MAINLY RAIN / FREEZING RAIN THIS MORNING...BUT COOLER AIR BY EARLY AFTERNOON COULD CAUSE A TRANSITION TO A RAIN / SNOW MIX. STRATUS ACROSS THE EASTERN PART OF NORTH DAKOTA HAS BEEN TRENDING STEADILY WESTWARD THIS MORNING. THE CURRENT FORECAST COVERS THIS WELL IN THE SKY GRIDS...BUT DECIDED TO MODIFY HIGH TEMPERATURES DOWNWARD A COUPLE OF DEGREES TOWARDS THE TURTLE MOUNTAINS WHERE THE CLOUDS WILL ARRIVE FIRST. UPDATE ISSUED AT 637 AM CST SAT NOV 30 2013 WEAK EMBEDDED ENERGY MOVING EAST-SOUTHEAST ACROSS MONTANA CONTINUES TO GENERATE EXTENSIVE CLOUDS FROM THE NORTHERN ROCKIES EAST ACROSS WEST INTO SOUTH CENTRAL NORTH DAKOTA. WITH SFC OBS REPORTING MAINLY OVC CONDITIONS...BEEFED UP SKY COVER. WILL MAINTAIN SLIGHT CHANCES FOR SNOW OR LIGHT FREEZING RAIN WEST CENTRAL INTO SOUTHWEST. EXPECT LITTLE MOISTURE IS REACHING THE GROUND WITH CIGS OVER 5K FEET AGL. HOWEVER...DID HAVE REPORTS OF -ZR AT WOLF POINT IN NORTHEAST MONTANA A COUPLE OF HOURS AGO...SO ALTHOUGH LIMITED WE SHOULD SEE ISOLATED PRECIP. CURRENT CLOUDS ARE PROJECTED TO REMAIN FOR MOST OF THIS MORNING IF NOT THROUGH THE AFTERNOON WITH ANOTHER WEAK IMPULSE APPROACHING MY NORTHWEST EARLY THIS AFTERNOON IN OUR NORTHWEST FLOW ALOFT. LAST BIG CHANGE WITH THIS UPDATE WAS TO INCREASE CLOUDS OVER MY NORTH CENTRAL TRENDING SOUTH. LARGE AREA OF LOW STRATUS TO OUR NORTH ACROSS SOUTH CENTRAL CANADA IS SLOWLY MOVING SOUTH. LATEST RAP AND NAM SHOW THE STRATUS REACHING MY NORTH CENTRAL/NORTHEAST 14-15Z THEN CONTINUING SOUTH AND EAST...REACHING THE JAMES VALLEY 18-21Z...AND THE SD BORDER BY MID EVENING...THEN PERSISTING THROUGH THE NIGHT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 501 AM CST SAT NOV 30 2013 REPORTS OF LIGHT FREEZING RAIN FROM NORTHEASTERN MONTANA CONFIRM THAT SOME OF THE PRECIPITATION INDICATED ON RADAR IMAGERY IS REACHING THE GROUND. IT APPEARS THIS ACTIVITY WILL SLOWLY SLIDE SOUTHEAST TODAY. WHILE TRAVEL IMPACTS ARE NOT EXPECTED...THERE COULD BE A BAND OR TWO OF PRECIPITATION THAT RESULTS IN ICY ROADS BETWEEN WILLISTON AND HETTINGER...AND WESTWARD TODAY. THERE WAS A LARGE SLOWDOWN IN THE ONSET OF PRECIPITATION FROM THE FIRST SHORTWAVE DUE INTO THE STATE ON SUNDAY. NOW...THE 00 UTC ECMWF/GFS/GEM GLOBAL/NAM ALL KEEP QPF OUT OF NORTH DAKOTA UNTIL SUNDAY MORNING AROUND 3 AM CST. PRECIPITATION CHANCES WERE HELD TO THE NORTHWESTERN COUNTIES UNTIL SUNRISE SUNDAY MORNING. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 501 AM CST SAT NOV 30 2013 A PROLONGED PERIOD OF WINTER WEATHER REMAINS THE MAIN HIGHLIGHT IN THE LONG TERM PERIOD...WITH INCREASING POTENTIAL FOR A MAJOR WINTER STORM TUESDAY-WEDNESDAY NIGHT. 00Z MODELS HAVE TRENDED INTO MUCH BETTER AGREEMENT FOR SUNDAY/SUNDAY NIGHT...WITH UNCERTAINTY DECREASING QUITE A BIT FOR MONDAY. UNCERTAINTY STILL REMAINS ELEVATED AFTERWARDS FOR TUESDAY AND ON. UPPER LEVEL LOW PRESSURE OVER ALASKA HAS STARTED ITS SOUTHWARD JOURNEY THIS MORNING...AND WILL TRACK SOUTH ALONG THE BRITISH COLUMBIA COAST OVER THE WEEKEND DROPPING INTO THE PACIFIC NORTHWEST ON MONDAY. AN UNASSOCIATED EMBEDDED S/WV IMPULSE CURRENTLY SOUTH OF THIS FEATURE OVER THE NORTHEAST PACIFIC WILL TRACK EAST-SOUTHEAST ONSHORE THIS MORNING THEN ACROSS THE ROCKIES TONIGHT ON THE NOSE OF AN UPPER LEVEL JET. LEE SIDE SFC TROUGH DEVELOPS TONIGHT IN RESPONSE TO THE INCREASING UPPER LEVEL DIVERGENCE. MODELS HAVE TRENDED SLOWER WITH PRECIPITATION INITIALIZATION WITH THERMAL UPGLIDE EAST OF THE TROUGH AND BEST DIVERGENCE ALOFT FOR ASCENT NOW TAKING PLACE OVER WESTERN NORTH DAKOTA 12-18Z SUNDAY MORNING. OVERRUNNING FLOW AND UPPER LEVEL SUPPORT IN THE LEFT EXIT REGION OF THE JET WILL SPREAD EASTWARD SUNDAY AFTERNOON AND EVENING. THIS FIRST WAVE OF MOISTURE STALLS ACROSS THE EAST GRADUALLY DIMINISHING AS FORCING WANES IN RESPONSE TO DECREASING SUPPORT ALOFT. GENERALLY LIGHT QPF WITH THIS FIRST WAVE UP TO A TENTH OF AN INCH OF MOISTURE...RESULTING IN SNOWFALL AMOUNTS MAYBE AROUND AN INCH NORTH AND EAST. STILL POTENTIAL FOR MIXED PRECIPITATION SOUTHWEST IN THE MORNING MAINLY IN THE FORM OF SLEET WITH THE WARM LAYER WET BULB AROUND 1-3C. RAIN WILL BE POSSIBLE ACROSS THE SOUTH CENTRAL WITH TEMPERATURES WARMING TO NEAR 40F IN THE AFTERNOON. MODELS HAVE COME INTO MUCH BETTER AGREEMENT WITH THE NEXT WAVE OF MOISTURE...ASSOCIATED WITH A POTENT LEAD SHORT WAVE ORIGINATING WITH THE UPPER LOW. PRECIPITATION IS FORECAST TO DEVELOP ACROSS MONTANA SUNDAY EVENING...SPREADING EASTWARD SUNDAY NIGHT INTO MONDAY DAYTIME ACROSS NORTH DAKOTA. MORE LIFT WILL BE PRESENT WITH THIS FEATURE MAKING IT MORE PRODUCTIVE THAN SUNDAY`S DISTURBANCE WITH PRECIPITATION PRODUCTION. QPF UP TO A QUARTER OF AN INCH WILL BE ADVERTISED WRAPPING AROUND A SFC LOW FORECAST TO MOVE FROM EASTERN MONTANA MONDAY MORNING INTO WESTERN SOUTH DAKOTA MONDAY EVENING. THIS TRACK PUTS THE HIGHER QPF OVER MY NORTH..CENTRAL...AND EAST. SIMILAR THERMAL PROFILE AS ON SUNDAY RESULTS IN ANOTHER CHANCE OF MIXED PRECIPITATION SOUTHWEST. SFC TEMPS MAY BE WARMER RESULTING IN MORE OF A RAIN/SNOW MIX VERSUS SLEET. IN FACT...MODELS WARM UP THE SOUTHWEST AND SOUTH CENTRAL TO SUPPORT ALL RAIN LATER MONDAY MORNING INTO THE AFTERNOON BEFORE CAA OVERTAKES THE STATE BY 00Z TUESDAY. WITH THE HIGHER QPF WILL SEE HIGHER SNOWFALL TOTALS...ONCE AGAIN ACROSS THE NORTH AND MY EAST WHERE ALL SNOW IS FORECAST...UP TO 4 INCHES POSSIBLE. THUS WILL NEED TO KEEP A CLOSE EYE ON MODEL TRENDS IN CASE A WINTER WEATHER ADVISORY BECOMES NEEDED LATE SUNDAY NIGHT THROUGH MONDAY. THIRD...FINAL...AND POSSIBLY GREATEST WAVE OF PRECIPITATION WILL INITIATE WEST LATE MONDAY NIGHT...POTENTIALLY LASTING THROUGH TUESDAY AND MUCH OF WEDNESDAY...AS THE UPPER LOW MOVES ACROSS THE ROCKIES THEN LIFTS THROUGH THE NORTHERN PLAINS SOMETIME TUESDAY NIGHT OR WEDNESDAY. STILL LOTS OF SPREAD AMONGST MODELS WITH A VARIETY OF SOLUTIONS PRESENT WHEN COMPARING THE 00Z RUNS OF THE GFS/GEM/ECMWF. THE LAST SEVERAL RUNS OF THE ECMWF HAVE BEEN THE MOST CONSISTENT...WHICH BRINGS THE HEAVIEST SNOW AND STRONGEST WINDS TO NORTH DAKOTA TUESDAY THROUGH WEDNESDAY NIGHT THANKS TO AN INVERTED SFC TROUGH ACROSS THE DAKOTAS. BOTH THE GFS AND GEM BRING LESS SNOW WITH THE GFS MUCH FASTER AND THE GEM FARTHER TO THE SOUTH WITH LOW PRESSURE. WILL CONTINUE TO MONITOR MODEL TRENDS CLOSE OVER THE NEXT FEW DAYS. WHILE THE SNOW POTENTIAL REMAINS UNCERTAIN MID-WEEK...MORE CONFIDENCE IN COLD ARCTIC AIR SURGING SOUTH IN THE UPPER LOWS WAKE WEDNESDAY INTO FRIDAY...AND REMAINING ENTRENCHED OVER THE NORTHERN PLAINS THROUGH NEXT WEEKEND. SUBZERO HIGHS ARE FORECAST...WITH LOWS 20 BELOW OR COLDER. WILL CONTINUE TO MENTION THE ABOVE HAZARDS IN A SPECIAL WEATHER STATEMENT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1258 PM CST SAT NOV 30 2013 AFTERNOON VISIBLE SATELLITE IMAGERY SHOW STRATUS ACROSS PARTS OF SOUTHERN CANADA MOVING SOUTH TOWARDS NORTHERN NORTH DAKOTA. THE LATEST RAP MODEL SUGGESTS THE STRATUS COULD REACH KMOT AND BY LATE AFTERNOON...AND THEN CONTINUE TO SPREAD SOUTH TONIGHT. LOWER CLOUDS ARE ALSO POSSIBLE AS A CHANCE OF PRECIPITATION MOVES TOWARDS THE REGION LATE TONIGHT INTO SUNDAY. OVERALL...WILL SHOW A DOWNWARD TREND IN REGARDS TO CEILINGS...WITH VISIBILITY RESTRICTIONS POSSIBLE AS PRECIPITATION CHANCES INCREASE. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CK SHORT TERM...SCHECK LONG TERM...NH AVIATION...CK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1224 PM CST SAT NOV 30 2013 .UPDATE... ISSUED AT 1224 PM CST SAT NOV 30 2013 ADJUSTED CLOUDS TO REFLECT CURRENT SAT TRENDS...AND ADDED SOME PATCHY FOG IN THE NORTHWEST WHERE LANGDON OBS AND WEB CAMS SHOW SOME REDUCED VIS. SOUTHWARD AND WESTWARD PROGRESSION OF THE LOW CLOUDS HAS SLOWED A BIT...SO BUMPED UP HIGHS SLIGHTLY IN THE FAR WEST AND SOUTHWEST WHERE THEY HAVE SEEN SOME SUN. LOWERED HIGHS A BIT IN THE NORTH AND CENTRAL COUNTIES WHERE STRATUS HAS KEEP US FROM RISING MORE THAN A FEW DEGREES. UPDATE ISSUED AT 946 AM CST SAT NOV 30 2013 LOWERED HIGHS FOR TODAY ACROSS THE NORTHWESTERN COUNTIES AND DROPPED THEM EVEN A DEGREE OR SO DOWN TO FARGO. CLEAR SKIES ALLOWED TEMPS AROUND KDVL TO DROP INTO THE LOWER TEENS...AND WITH STRATUS MOVING IN THERE WILL BE NOT TOO MUCH RISE THIS AFTERNOON. AT THIS TIME THE SOUTHWESTERN CWA COULD STILL SEE SOME SUN AND CLIMB INTO THE MID 30S...BUT THERE ARE MORE MID CLOUDS MOVING IN FROM THE WEST. MADE SOME FURTHER TWEAKS TO CLOUDS AND WILL KEEP AN EYE ON TEMPS IN CASE THEY NEED TO BE DROPPED MORE LATER ON TODAY. UPDATE ISSUED AT 644 AM CST SAT NOV 30 2013 WILL NEED TO INCREASE SKY TODAY. THE RAP GUIDANCE IS VERIFYING THE BEST...SHOWING THE LOW LEVEL CIGS FROM CANADA ADVECTING INTO THE FORECAST AREA. WILL FOLLOW THE 09Z RAP FOR ARRIVAL TIMES. WILL ALSO KEEP THE REGION CLOUDY THROUGH THE OVERNIGHT HOURS. FORECASTED MAX TEMPS TODAY MAY BE A BIT HIGH...BUT SHOULD BE IN THE BALL PARK. FORECASTED MIN TEMPS TONIGHT ARE LIKELY TOO COLD (IF CLOUDS STICK AROUND AS EXPECTED). WILL CONCENTRATE ON SKY FOR THIS UPDATE...AND WORRY ABOUT TEMPS WITH THE NEXT UPDATES. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 337 AM CST SAT NOV 30 2013 00Z MODELS INITIALIZED WITH MINIMAL ERRORS AND ARE IN GOOD AGREEMENT THROUGH SUNDAY. THE CHALLENGE FOR TODAY WILL BE TEMPERATURES AND CLOUD COVER. THE CHALLENGE FOR SUNDAY WILL BE -SN CHANCES. TODAY-TONIGHT...WEAK COLD FRONT WILL BE THROUGH THE REGION WHICH SHOULD LEAD TO SLIGHTLY COOLER TEMPERATURES THAN YESTERDAY. THE MID-LEVEL CLOUDS ALONG AND AHEAD OF THIS FEATURE WILL MOVE SOUTH...BUT WILL NEED TO WATCH THE LOW-LEVEL CIGS APPROACHING FROM THE NORTH. 06Z RAP IS MOST AGGRESSIVE BRINGING THESE CIGS INTO THE ENTIRE FA...WHILE MOST OTHER GUIDANCE SUGGESTS ONLY PORTIONS OF NW MN WILL BE AFFECTED. WILL SIDE WITH THE MAJORITY...AND TAKE A CLOSER LOOK AT THE 7AM UPDATE. SUNDAY...00Z MODELS HAVE SLOWED THE SHORTWAVE BRINGING -SN CHANCES...ADJUSTED POPS ACCORDINGLY. MUCH OF SUNDAY SHOULD BE DRY (UNTIL THE EVENING HOURS). .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 337 AM CST SAT NOV 30 2013 SUNDAY NIGHT-MONDAY NIGHT...00Z MODELS BEGIN TO DIVERGE...WITH THE ECMWF/GEM/UKMET DIGGING THE UPPER LOW INTO THE NW CONUS BY 12Z TUE...AND THE NAM/GFS BRINGING THIS FEATURE INTO MONTANA/WESTERN DAKOTAS. THE ECMWF/GEM/UKMET HAVE BEEN THE MORE CONSISTENT MODELS...AND ARE SUPPORTED BY ENSEMBLES (WILL FOLLOW FOR FORECAST DETAILS). THERE WILL BE A COUPLE LEAD SHORTWAVES EJECTING FROM THE MAIN UPPER TROUGH. THE FIRST WILL MOVE THROUGH THE REGION SUNDAY NIGHT...AND THE SECOND MONDAY AFTERNOON/NIGHT. SINCE THERE HAVE BEEN A FEW MODEL RUNS INDICATING THESE FEATURES...WILL INCREASE POPS TO LIKELY AND ATTEMPT TO TIME THESE FEATURES THROUGH THE REGION. THE FIRST WAVE IS WEAKER...AND SHOULD HAVE LESS AVAILABLE MOISTURE. MESOSCALE FORCING IS ALSO WEAK...SO UP TO AN INCH OF SNOWFALL APPEARS POSSIBLE (MAYBE 2 INCHES). THE SECOND WAVE IS STRONGER...WITH MORE AVAILABLE MOISTURE (PWATS APPROACHING 0.5 INCHES). MODELS INDICATE A DEFINED CIRCULATION AT 850MB (AND A WEAK 700MB LOW) PROPAGATING FROM NW ND INTO SE ND ON MONDAY...LOSING DEFINITION MONDAY NIGHT AS IT PROPAGATES FURTHER TO THE SE. ASSOCIATED WARM AIR ADVECTION/DEFORMATION COMBINED WITH THE 0.5 INCH PWATS SHOULD LEAD TO A FEW INCHES OF SNOWFALL. MODELS INDICATE 0.25-0.40 INCHES QPF ACROSS ALL BUT THE NE FA...AND COMBINED WITH 12:1-13:1 SNOW RATIOS WOULD LEAD TO AN AREA OF 3-5 INCHES OF SNOW. P-TYPE WILL BE ALL SNOW IF THE EXPECTED SOLUTION VERIFIES. THE NAM/SREF/GFS HAVE WARMER MID-LEVEL TEMPERATURES SINCE THE UPPER WAVE IS CLOSER TO THE REGION (LOW LEVEL SOUTHERLY FLOW IS STRONGER)...AND WOULD LEAD TO FZRA/RA POTENTIAL (BUT THIS PROBABILITY SEEMS VERY LOW ATTM). TUESDAY-FRIDAY...A VERY WINTRY PERIOD IS IN STORE...WITH THE MAIN FOCUS INITIALLY BEING SNOW POTENTIAL THROUGH MID-WEEK FOLLOWED BY A COLD ARCTIC AIR MASS SPILLING SOUTH. MODEL SPREAD CONTINUES TO BE SIGNIFICANT...ALTHOUGH THE ECMWF HAS SHOWN BETTER CONSISTENCY OVER THE PAST FEW RUNS...SO HAVE TRENDED A BIT IN THAT DIRECTION. THE 00Z GFS/ECMWF BOTH BRING THE UPPER TROUGH EASTWARD INTO THE PLAINS WED/THU. HOWEVER...A CHALLENGE CONTINUES TO BE TIMING OF EMBEDDED WAVES. THE ECMWF REMAINS DEEPEST AND FARTHEST WEST WITH SFC LOW DEVELOPMENT FROM THE CENTRAL PLAINS NORTHEAST INTO ONTARIO IN CONJUNCTION WITH A STRONG SHORTWAVE TROUGH ASSOCIATED WITH THE LIFTING UPPER LOW...WHILE THE GFS IS MORE PROGRESSIVE WITH A WEAKER SFC LOW ASSOCIATED WITH A LEAD WAVE. THUS...THE ECMWF AND TO A LESSER EXTENT THE GEM ARE MORE AGGRESSIVE WITH QPF. THE 500 MB GFS ENSEMBLE MEAN HEIGHT FIELD GENERALLY SUPPORTS THE ECMWF BROADLY. CONFIDENCE STILL IS RATHER LOW REGARDING THE PLACEMENT AND MAGNITUDE OF SNOWFALL...ALTHOUGH THE MID-WEEK PERIOD WILL CONTINUE TO BEAR WATCHING FOR ACCUMULATING SNOWFALL. ARCTIC AIR WILL BLAST SOUTH DURING THE LATTER PART OF THE WEEK INTO NEXT WEEKEND. THE ECMWF CONTINUES TO INDICATE 925 MB TEMPS DOWN TO -20 TO -25C THURSDAY/FRIDAY BEHIND INITIAL SURGE OF COLD ADVECTION. BLUSTERY WINDS WILL COMBINE WITH VERY COLD TEMPS TO PRODUCE POTENTIALLY HAZARDOUS WIND CHILLS AT TIMES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1224 PM CST SAT NOV 30 2013 MAIN CHALLENGE FOR AVIATION IS CIGS. BAND OF MVFR/IFR CIGS SPREADING OVER THE AREA AND OBS UPSTREAM SHOWS SOME VARIANCE BETWEEN 800 TO 1500 FEET. HARD TO NAIL DOWN EXACT CIG HEIGHTS WITH THE STRATUS DECK...SO WENT WITH PERSISTENCE ATTM AND KEPT CIGS GENERALLY AROUND 1000 FEET. EXPECT SOME VARIABILITY IN VSBY AS WELL...BUT WILL KEEP IN VFR CATEGORY FOR NOW. OTHERWISE...VERY WEAK PRESSURE GRADIENT IS EXPECTED TO PERSIST OVER THE AREA THRU THE TAF PERIOD SO KEPT WINDS ON THE LIGHT SIDE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...JR SHORT TERM...TG LONG TERM...TG/MAKOWSKI AVIATION...HOPKINS
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
1123 AM CST SAT NOV 30 2013 .UPDATE... UPDATE TO 18Z AVIATION DISCUSSION BELOW. NO MAJOR CHANGES MADE TO THE FORECAST THIS MORNING. CURRENT RADAR IMAGES SHOW SOME WEAK ECHOES PUSHING OVER THE NORTHWESTERN CWA AT THIS TIME...SO WILL STICK WITH A SCHC POP IN THAT AREA...WITH LITTLE IN THE WAY OF RAINFALL ACCUMULATION EXPECTED. NO CHANGES MADE TO WINDS OR TEMPERATURES AT THIS TIME. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH MONDAY CHANCES FOR PRECIPITATION AS WELL AS P-TYPE WILL BE THE FORECAST CHALLENGES. A WEAK MID LEVEL SHORT WAVE CURRENTLY OVER MONTANA WILL TRACK SOUTHEASTWARD ACROSS THE REGION TODAY...BRINGING PARTLY CLOUDY SKIES TO THE CWA. THE PAST FEW RUNS OF THE RUC AND THE NSSL WRF BOTH SHOW SOME LIGHT RAIN FOR THE FAR NW PORTION OF THE CWA...PERHAPS REACHING KMBG BY THIS AFTERNOON. THUS HAVE ADDED A LOW POP. ANOTHER MID LEVEL SHORT WAVE AND FRONTAL BOUNDARY WILL TRACK ACROSS THE REGION ON SUNDAY. MODELS HAVE SIGNIFICANTLY SLOWED DOWN THE PROGRESSION OF THE TROUGH...WITH PCPN NOT REACHING THE JAMES RIVER VALLEY UNTIL AFTER 18Z. IT STILL APPEARS AS THOUGH THE LEADING EDGE OF THE PCPN WILL FALL AS ALL SNOW. HOWEVER WITH WAA QUICKLY PUSHING IN ON THE BACK SIDE...THE SNOW WILL TRANSITION OVER TO ALL RAIN. THIS SYSTEM DOES NOT CONTAIN A GREAT DEAL OF LOW LEVEL MOISTURE SO WILL MAINTAIN CHC POP ALONG THE ND/SD BORDER FOR NOW. A MUCH STRONGER STORM SYSTEM WILL BEGIN IMPACTING THE REGION ON MONDAY. HOWEVER MODELS ARE NOT IN A REAL GOOD AGREEMENT WITH THE OVERALL PLACEMENT OF THIS MID LEVEL CLOSED LOW...WHICH LEADS TO A LOW FORECASTER CONFIDENCE. EVEN WITH A DISAGREEMENT ON THE PLACEMENT THERE IS A GENERAL CONSENSUS THAT TEMPERATURES WILL BE WARM ENOUGH TO SUPPORT A MOSTLY RAIN EVENT. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY STILL NOT A LOT OF CONFIDENCE WITH THE FINER DETAILS WITHIN THE EXTENDED...THOUGH TWO GENERAL TRENDS CAN BE EXPECTED. THE FIRST WILL BE THE INFLUENCE OF A BROAD UPPER TROF AND EMBEDDED SHORTWAVES MOVING ACROSS THE NORTHERN TIER CONUS. MOST OF THE PRECIPITATION WILL BE ASSOCIATED WITH AN H7 LOW THAT LOOKS TO TRACK ACROSS NORTH DAKOTA/MINNESOTA...THOUGH IT MAY PIVOT THROUGH WESTERN SOUTH DAKOTA DEPENDING ON THE MODEL. THIS TRACK SUGGESTS NORTH DAKOTA WILL RECEIVE THE MAJORITY OF PRECIPITATION WITHIN THE WARM ADVECTION BAND AND ANY TROWAL BASED WRAP AROUND. THE GFS IS GENERALLY WEAKER WITH SIGNIFICANTLY LOWER PRECIPITATION POTENTIAL. THE ECMWF IS STRONGER...WITH A MORE SOUTHERLY TRACK...AND STRONGER WINDS WITH POTENTIALLY MORE IMPACTS TO THE CWA. THE SECOND FEATURE WILL BE ANOMALOUSLY COLD AIR POURING INTO THE REGION. TIMING DIFFERENCES CONTINUE BETWEEN THE GFS AND ECMWF...VARYING BETWEEN TUESDAY AND WEDNESDAY RESPECTIVELY. BOTH MODELS RESOLVE THE COLD POOL WITH SIMILAR INTENSITY AND DURATION...AS IT WILL COME TO DOMINATE THE WEATHER THROUGH THE END OF THE WORK WEEK. UNFORTUNATELY...BOTH MODELS HAVE BEEN REASONABLY CONSISTENT WITH THEIR INDIVIDUAL TRENDS. WILL CONTINUE TO BROADBRUSH THE FIRST FEW PERIODS OF THE EXTENDED WITH CHANCE POPS/SNOW UNTIL MODELS ENTER BETTER ALIGNMENT. && .AVIATION... 18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS EXPECTED AT ALL TERMINALS WITH WINDS UNDER 10 KTS. A MID LEVEL CLOUD DECK WILL MOVE ACROSS THE AREA TODAY AND OVERNIGHT AOA 5 KFT. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...PARKIN SHORT TERM...SD LONG TERM...CONNELLY AVIATION...SCARLETT WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1116 AM CST SAT NOV 30 2013 .UPDATE... ISSUED AT 1116 AM CST SAT NOV 30 2013 TEMPERATURES WARMING EVEN FASTER THAN FORECAST AND CURRENTLY 5 TO 10 DEGREES WARMER THAN RAP AND NAM. WHILE STRONG INVERSION WILL EVENTUALLY SLOW THE RISE...EXPECT THAT AREAS ALONG AND SOUTH OF I90 WILL MIX TO AROUND 900 MB. THIS FAVORS TEMPERATURES CLOSE TO 50 ALONG I-90 AND INTO THE LOWER 50S IN THE MISSOURI VALLEY AND PORTIONS OF NORTHWEST IOWA. DESPITE THE WARMER TEMPERATURES... WINDS WILL NOT BE MUCH STRONGER...10 MPH OR LESS IN MOST AREAS. DID NOT WARM QUITE AS MUCH ALONG HWY 14 IN EAST CENTRAL SD AND SW MN DUE TO MORE CLOUDS THIS AFTERNOON. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 345 AM CST SAT NOV 30 2013 A MILD AND MUCH LESS WINDY DAY TODAY AS A WEAK BOUNDARY MOVES INTO THE AREA. WHILE THE LOWER AND MID LEVEL THERMAL FIELD WILL BE A LITTLE COOLER THAN YESTERDAY BETTER MIXING SHOULD SUPPORT WARMER READINGS. WITH QUITE A FEW 50S TO THE WEST YESTERDAY AND THAT AIR MASS MOVING INTO THE AREA WILL GO AHEAD AND RAISE IN MOST LOCATIONS...ESPECIALLY WITH THE THOUGHT THAT CLOUD COVER WILL BE A LITTLE LESS THROUGH MID AFTERNOON THAN PREVIOUSLY THOUGHT. DO EXPECT SOME MID LEVEL CLOUDS TO REACH THE HIGHWAY 14 CORRIDOR BY ABOUT MID DAY BUT THE INTERSTATE 90 CORRIDOR AND POINTS SOUTH SHOULD HOLD OFF UNTIL AT LEAST MID AFTERNOON. FULL MIXING TO 900MB OR SO IN THE SOUTHERN CWA SUPPORT ABOUT 52 TO 53 SO FOR NOW WILL GO ABOUT 50 IN THIS AREA WHICH LEAVES A BIT OF WIGGLE ROOM IN CASE MIXING IS NOT QUITE AS GOOD AS EXPECTED BUT WITH NO SNOW COVER SUSPECT THAT IT WILL BE. THE REST OF THE AREA SHOULD BE MAINLY MID TO UPPER 40S WITH SOME LOWER 40S ALONG THE HIGHWAY 14 CORRIDOR WHERE CLOUDS MOVE IN QUICKER. SHOULD BE FAIRLY MILD OVERNIGHT ALTHOUGH IT WILL BE A BATTLE BETWEEN LIGHT WINDS...NO SNOW COVER AND SOME CLOUD COVER. WILL GO WITH MAINLY UPPER TEENS TO LOWER 20S. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 345 AM CST SAT NOV 30 2013 RELATIVELY QUIET WEATHER PATTERN CONTINUES INTO SUNDAY WITH LARGE TROUGH BECOMING BETTER ORGANIZED OVER THE WEST COAST AND SURFACE HIGH PRESSURE DOMINATING ACROSS THE EASTERN TWO THIRDS OF THE COUNTRY. MODELS SHOW A FAIR AMOUNT OF MID AND HIGH LEVEL CLOUDS STREAMING INTO THE FORECAST AREA. THERE IS EVEN SOME WEAK LIFT THAT DEVELOPS ACROSS THE NORTHERN EDGE OF THE FORECAST AREA AS A WEAK INITIAL WAVE PASSES BY...BUT THE LOWEST 4-5K FEET REMAIN UNSATURATED MAKING IT TOUGH FOR THE PRECIPITATION TO REACH THE SURFACE. HAVE A SLIGHT CHANCE OF RAIN OR SNOW IN THE LATE AFTERNOON HOURS ALONG THE HIGHWAY 14 CORRIDOR...BUT OTHERWISE EXPECT DRY CONDITIONS TO PREVAIL. THROUGH THE EVENING HOURS SOUNDINGS WET BULB DOWN TO SNOW FAIRLY QUICK AS ANOTHER WEAK WAVE PASSES TO THE NORTH. COULD SEE SOME LIGHT SNOW WITH THIS WAVE ACROSS THE NORTHEAST HALF OF THE FORECAST AREA SUNDAY NIGHT...BUT ANYTHING THAT FALLS WILL BE VERY LIGHT. MONDAY APPEARS TO BE DRY AND SOMEWHAT MILD AS WARM FRONT PIVOTS THROUGH THE REGION RESULTING IN A FAIR AMOUNT OF WARMING. 925 HPA TEMPS WARM WELL INTO THE SINGLE DIGITS ABOVE FREEZING...AND HAVE RAISED FORECAST HIGHS WITH GREATEST FOCUS FOR WARMING WEST OF THE JAMES RIVER VALLEY. SOUTHERLY WINDS SHOULD AID IN THE WARMING...WHILE A FAIR AMOUNT OF CLOUD COVER IS EXPECTED AS SURFACE LOW WORKS IN NORTH DAKOTA. MODEL AGREEMENT REALLY STARTS TO DISINTEGRATE THEREAFTER WITH GFS OFFERING A MORE PROGRESSIVE EVOLUTION OF THE LOW THAN THE ECMWF. WITH MODELS INDICATING A FAIRLY SIGNIFICANT CYCLONE AND JET ENERGY HANGING BACK ON THE WEST SIDE OF THE TROUGH THROUGH AT LEAST MID DAY TUESDAY...HAVE SIDED TOWARDS THE SLOWER EVOLUTION OF THIS SYSTEM. CONTINUED MENTION OF MID RANGE POPS MONDAY NIGHT - TUESDAY WITH INCREASE IN POPS ON WEDNESDAY. OVERALL...APPEARS AS THOUGH MUCH OF THE MID AND UPPER LEVEL FORCING REMAINS TO THE NORTH AND WEST. IF WE WERE ABLE TO GET PRECIP HERE...WOULD BE A TOUGH CALL BUT APPEARS TO BE SOME SORT OF MIXTURE TO THE SOUTH WITH SNOW DOMINANTLY FALLING ACROSS THE NORTH AND WEST. MODELS SHOW FALLING TEMPERATURES ON WEDNESDAY THROUGH THE REMAINDER OF THE EXTENDED AS INVERTED TROUGH SHIFTS THROUGH WITH MUCH COOLER AIR POURING INTO THE NORTHERN PLAINS. HAVE SQUASHED THE DIURNAL RANGE ON WEDNESDAY ACROSS THE WEST...WITH LESS MANIPULATION FURTHER TO THE SOUTH AND EAST. HAVE ALSO LOWERED FORECAST HIGHS ON THURSDAY WITH -15 TO -17 DEGREE AIR ACROSS THE FORECAST AREA AT 925 HPA. HAVE ALSO RAISED WINDS CLOSER TO MOS VALUES UNDER THE INFLUENCE OF STRONG COLD AIR ADVECTION. AT THIS POINT...DID NOT GO STRONGLY COOL...AS LIMITED SNOW COVER MAY AID IN SOME MIXING. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1116 AM CST SAT NOV 30 2013 LIGHT WINDS AND VFR CLOUDS AND CIGS EXPECTED THROUGH 18Z AT TAF LOCATIONS...KFSD...KSUX AND KHON. CIGS WILL BE LOWERING OVERNIGHT AND INTO SUNDAY MORNING ACROSS SE SD AS WARM FRONT APPROACHES BUT WITH VERY DRY LOW LEVEL AIR MASS DO NOT EXPECT PRECIPITATION TO DEVELOP. HOWEVER...CIGS COULD FALL TO AS LOW AS 4000 FT ON SUNDAY MORNING. OTHER CONCERN IS STRATUS IN THE RED RIVER VALLEY OF ND AND NW MN. LOW LEVEL TRAJECTORIES BRING THESE CLOUDS INTO THE MINNESOTA RIVER VALLEY THIS EVENING AND MAY RESULT IN MVFR CIGS AS FAR WEST AS KMML AND KMWM THIS EVENING BEFORE CLOUDS BEGIN TO MOVE EAST TOWARD SUNRISE. WINDS THROUGH THE PERIOD WILL BE LESS THAN 10 KTS...FROM THE NORTHWEST THIS AFTERNOON AND EVENING...AND FROM THE SOUTHEAST ON SUNDAY MORNING. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ UPDATE...SCHUMACHER SHORT TERM...08 LONG TERM... AVIATION...SCHUMACHER
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1021 AM CST SAT NOV 30 2013 .UPDATE... NO MAJOR CHANGES MADE TO THE FORECAST THIS MORNING. CURRENT RADAR IMAGES SHOW SOME WEAK ECHOES PUSHING OVER THE NORTHWESTERN CWA AT THIS TIME...SO WILL STICK WITH A SCHC POP IN THAT AREA...WITH LITTLE IN THE WAY OF RAINFALL ACCUMULATION EXPECTED. NO CHANGES MADE TO WINDS OR TEMPERATURES AT THIS TIME. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH MONDAY CHANCES FOR PRECIPITATION AS WELL AS P-TYPE WILL BE THE FORECAST CHALLENGES. A WEAK MID LEVEL SHORT WAVE CURRENTLY OVER MONTANA WILL TRACK SOUTHEASTWARD ACROSS THE REGION TODAY...BRINGING PARTLY CLOUDY SKIES TO THE CWA. THE PAST FEW RUNS OF THE RUC AND THE NSSL WRF BOTH SHOW SOME LIGHT RAIN FOR THE FAR NW PORTION OF THE CWA...PERHAPS REACHING KMBG BY THIS AFTERNOON. THUS HAVE ADDED A LOW POP. ANOTHER MID LEVEL SHORT WAVE AND FRONTAL BOUNDARY WILL TRACK ACROSS THE REGION ON SUNDAY. MODELS HAVE SIGNIFICANTLY SLOWED DOWN THE PROGRESSION OF THE TROUGH...WITH PCPN NOT REACHING THE JAMES RIVER VALLEY UNTIL AFTER 18Z. IT STILL APPEARS AS THOUGH THE LEADING EDGE OF THE PCPN WILL FALL AS ALL SNOW. HOWEVER WITH WAA QUICKLY PUSHING IN ON THE BACK SIDE...THE SNOW WILL TRANSITION OVER TO ALL RAIN. THIS SYSTEM DOES NOT CONTAIN A GREAT DEAL OF LOW LEVEL MOISTURE SO WILL MAINTAIN CHC POP ALONG THE ND/SD BORDER FOR NOW. A MUCH STRONGER STORM SYSTEM WILL BEGIN IMPACTING THE REGION ON MONDAY. HOWEVER MODELS ARE NOT IN A REAL GOOD AGREEMENT WITH THE OVERALL PLACEMENT OF THIS MID LEVEL CLOSED LOW...WHICH LEADS TO A LOW FORECASTER CONFIDENCE. EVEN WITH A DISAGREEMENT ON THE PLACEMENT THERE IS A GENERAL CONSENSUS THAT TEMPERATURES WILL BE WARM ENOUGH TO SUPPORT A MOSTLY RAIN EVENT. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY STILL NOT A LOT OF CONFIDENCE WITH THE FINER DETAILS WITHIN THE EXTENDED...THOUGH TWO GENERAL TRENDS CAN BE EXPECTED. THE FIRST WILL BE THE INFLUENCE OF A BROAD UPPER TROF AND EMBEDDED SHORTWAVES MOVING ACROSS THE NORTHERN TIER CONUS. MOST OF THE PRECIPITATION WILL BE ASSOCIATED WITH AN H7 LOW THAT LOOKS TO TRACK ACROSS NORTH DAKOTA/MINNESOTA...THOUGH IT MAY PIVOT THROUGH WESTERN SOUTH DAKOTA DEPENDING ON THE MODEL. THIS TRACK SUGGESTS NORTH DAKOTA WILL RECEIVE THE MAJORITY OF PRECIPITATION WITHIN THE WARM ADVECTION BAND AND ANY TROWAL BASED WRAP AROUND. THE GFS IS GENERALLY WEAKER WITH SIGNIFICANTLY LOWER PRECIPITATION POTENTIAL. THE ECMWF IS STRONGER...WITH A MORE SOUTHERLY TRACK...AND STRONGER WINDS WITH POTENTIALLY MORE IMPACTS TO THE CWA. THE SECOND FEATURE WILL BE ANOMALOUSLY COLD AIR POURING INTO THE REGION. TIMING DIFFERENCES CONTINUE BETWEEN THE GFS AND ECMWF...VARYING BETWEEN TUESDAY AND WEDNESDAY RESPECTIVELY. BOTH MODELS RESOLVE THE COLD POOL WITH SIMILAR INTENSITY AND DURATION...AS IT WILL COME TO DOMINATE THE WEATHER THROUGH THE END OF THE WORK WEEK. UNFORTUNATELY...BOTH MODELS HAVE BEEN REASONABLY CONSISTENT WITH THEIR INDIVIDUAL TRENDS. WILL CONTINUE TO BROADBRUSH THE FIRST FEW PERIODS OF THE EXTENDED WITH CHANCE POPS/SNOW UNTIL MODELS ENTER BETTER ALIGNMENT. && .AVIATION... 12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS EXPECTED AT ALL TERMINALS. LIGHT WINDS WILL BE OUT OF THE NORTHWEST GRADUALLY SHIFTING TO THE NORTH. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...PARKIN SHORT TERM...SD LONG TERM...CONNELLY AVIATION...CONNELLY WEATHER.GOV/ABERDEEN