Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 02/27/13


AREA FORECAST DISCUSSION
NWS PUEBLO CO
746 PM MST TUE FEB 26 2013 .UPDATE... ISSUED AT 740 PM MST TUE FEB 26 2013 ISSUED A SHORT FUSED WINTER WEATHER ADVISORY FOR NORTHERN EL PASO COUNTY...AS WINDS HAVE INCREASED AND BANDS OF MODERATE TO HEAVY SNOW CONTINUE TO ROTATE SOUTH. LATEST HRRR KEEPS PRECIP GOING UNTIL 08Z...AND SHOWS WIND GUSTS OVER 30 KTS NEAR THE PALMER DIVIDE UNTIL AT LEAST 10Z. HAVE HAD NUMEROUS REPORTS OF ROAD CLOSURES/DIFFICULT TRAVEL DUE TO WIDESPREAD BLOWING/DRIFTING SNOW NORTH AND EAST OF COS. FORECASTS FOR THE REMAINDER OF THE AREA WERE REFRESHED TO ACCOUNT FOR ONGOING PRECIP. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 325 PM MST TUE FEB 26 2013 SHORT TERM METEOROLOGICAL ISSUES INCLUDE BUT ARE NOT LIMITED TO POPS/SNOW AMOUNTS...WINDS AND TEMPERATURES. FORECAST DISTRICT CURRENTLY NOTING SNOW ACTIVITY...ESPECIALLY OVER THE MOUNTAINS AND HIGHER TERRAIN AREAS AS WELL AS OVER MANY PORTIONS OF THE I-25 CORRIDOR AS WELL AS AREAS OF GUSTY NORTH WINDS. AS OF 3 PM MST...REPORTED SNOW AMOUNTS HAVE GENERALLY BEEN UNDER 4 INCHES...I.E RECENTLY RECEIVED A SPOTTER SNOW REPORT OF 3.5 INCHES OF SNOW 11 MILES TO THE NORTH-NORTHEAST OF CRESTONE IN CUSTER COUNTY(PUBLIC ZONE 72) WITH LIGHT SNOW CONTINUING. LATEST SHORT/NEAR-TERM COMPUTER SIMULATIONS...FORECAST MODEL SOUNDINGS AND REAL-TIME DATA INDICATE THAT THE UPPER DISTURBANCE WILL CONTINUE TO IMPACT MANY SECTIONS OF THE CWFA INTO TONIGHT BEFORE SHIFTING EAST OF THE FORECAST DISTRICT BY WEDNESDAY MORNING. STILL EXPECT THAT 4 TO 8 INCH SNOW TOTALS(INCLUDING SNOW THAT HAS ALREADY FALLEN EARLIER TODAY...I.E. 12 TO 18 HOUR TIME-RANGE) WILL BE POSSIBLE OVER MANY MOUNTAIN AND HIGHER FOOTHILL LOCATIONS WITH 2 TO 5 INCHES OF SNOW OVER NORTHERN EL PASO COUNTY AND 2 INCHES OR LESS OF SNOW ELSEWHERE WILL BE NOTED BEFORE THIS EVENT ENDS LATER TONIGHT. IN ADDITION...A FEW LOCALLY HIGHER SNOW AMOUNTS WILL ALSO BE POSSIBLE BY SUNRISE WEDNESDAY. IN ADDITION TO THE SNOW FROM THIS AFTERNOON INTO TONIGHT...GUSTY NORTH WINDS AT TIMES ARE ALSO EXPECTED IN COMBINATION WITH CONTINUED BELOW SEASONAL LATE FEBRUARY TEMPERATURES. FOR WEDNESDAY...AS UPPER SYSTEM DEPARTS SOUTHERN COLORADO...ANTICIPATE THAT GENERALLY DRY CONDITIONS IN COMBINATION WITH CLEARING SKIES...DECREASING WINDS(EXCEPT FOR POSSIBLY FAR EASTERN SECTIONS) AND WARMER TEMPERATURES(ALTHOUGH STILL BELOW LATE FEBRUARY CLIMATOLOGICAL AVERAGES) WILL BE NOTED ACROSS THE FORECAST DISTRICT. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 325 PM MST TUE FEB 26 2013 WED NIGHT...GENERALLY DRY NW FLOW ALOFT WL BE OVR THE AREA...BUT THERE COULD BE A FEW SHOWERS OVR THE CONTDVD MAINLY IN THE EVENING HOURS. FORECAST MODELS DO NOT AGREE ON THE WEATHER FOR LATE THU AND THU NIGHT. THE GFS HAS THE AREA MOSTLY DRY INTO THE EARLY AFTERNOON...BUT LATE IN THE AFTERNOON A SHORTWAVE TROF DROPS INTO SWRN WY AND AHEAD OF THIS SYSTEM...WITH MOISTURE INCREASING AND THE GFS BRINGS CHANCES FOR SNOW TO THE CENTRAL MTS AND TO THE PIKES PEAK TELLER COUNTY REGION. THEN THU NIGHT THAT SYSTEM DROP SOUTH THU CO...SPREADING PCPN CHANCES SOUTHWARD AS WELL. THE NAM AND THE ECMWF DO NOT HAVE THIS SHORTWAVE TROF AND IS KEEPING THE WEATHER DRY. WL STICK WITH SOME PCPN IN THE CENTRAL MTS...WITH MAYBE JUST A FEW SHOWERS OVR THE OTHER MTN PEAKS AND SEE WHAT FUTURE MODEL RUNS BRING. FRI...AS AN UPR LOW DROPS INTO WRN MO AND ERN KS A FRONT BRING SOME BREEZY NORTHERLY WINDS TO MUCH OF THE EASTERN CO PLAINS. THE NAM IS MOSTLY DRY OVR THE AREA FOR FRI...WHILE THE GFS AND ECMWF BOTH SHOW SOME POTENTIAL FOR PCPN OVR THE MTS AND ERN PLAINS. AN UPR RIDGE THEN BUILD OVR THE AREA FOR THE WEEKEND...RESULTING IN DRY WEATHER AND WARMER TEMPS. LATE SUN THE UPR RIDGE GETS FLATTENED OVR THE AREA AS A NEW UPR LOW MOVES INTO WRN MT. THE TRACK OF THAT UPR LOW IS THEN QUITE UNCERTAIN AS THE GFS BRINGS IT SOUTHEASTWARD AND ACRS NORTHEAST CO BY MIDDAY MON WHILE THE ECMWF STILL HAS IT OVR MT. BY 06Z TUE THE GFS MOVES THE LOW INTO NRN MO...WHILE THE ECMWF HAS IT OVR SRN MT AND NRN WY. THUS ITS HARD TO SAY EXACTLY WHAT IS IN STORE FOR THE FORECAST AREA SUN NIGHT AND MON BUT FOR NOW BOTH MODELS AT LEAST HAVE SOME PCPN OVR THE CENTRAL MTS. WL PROBABLY SEE A SHORTWAVE RIDGE AND MAINLY DRY WEATHER OVR THE AREA ON TUE. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 325 PM MST TUE FEB 26 2013 A WEATHER DISTURBANCE WILL CONTINUE TO PUSH ACROSS THE AVIATION DISTRICT THROUGH TONIGHT...ALLOWING AREAS OF SNOW AND LOWER CIGS...CAPABLE OF PRODUCING MVFR TO LIFR CONDITIONS AT TIMES...ESPECIALLY AT KCOS AND KPUB. VFR CONDITIONS SHOULD THEN RETURN TO THE KALS...KCOS AND KPUB TAF SITES BY WEDNESDAY MORNING AND CONTINUE INTO WEDNESDAY AFTERNOON. && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 2 AM MST WEDNESDAY FOR COZ084. && $$ UPDATE...PETERSEN SHORT TERM...77 LONG TERM...28 AVIATION...77
AREA FORECAST DISCUSSION
NWS DES MOINES IA
543 PM CST TUE FEB 26 2013 ...UPDATED FOR THE 00Z AVIATION DISCUSSION... .SHORT TERM /TONIGHT/... WINTER STORM WILL PERSIST THROUGH WEDNESDAY MORNING AS LIGHT TO MODERATE SNOW BANDING CONTINUES ON THE BACKSIDE OF THE SURFACE LOW LOCATED IN SOUTHEAST MISSOURI. SURFACE LOW LOOKS TO SLOWLY MIGRATE NORTHEAST FROM SOUTHEAST MISSOURI INTO CENTRAL ILLINOIS THIS EVENING INTO TOMORROW MORNING. LEANED TOWARD A SREF/GFS/NAM12 BLEND FOR TRENDS TONIGHT. WEAK LIFT WITHIN THE DENDRITIC GROWTH ZONE CONTINUES THIS AFTERNOON AND TONIGHT...AND EVEN PERSISTS INTO WEDNESDAY MORNING. HIGHER CONFIDENCE WITH THE ADDITIONAL LIGHT SNOW AMOUNTS THROUGH WEDNESDAY MORNING RESULTING IN ROUGHLY 1 TO 4 INCHES OF ADDITIONAL SNOW THROUGH 12Z ACROSS THE WARNING AREA. THE SNOW BAND AXIS LOOKS TO CONTINUE TO SLOWLY PIVOT COUNTERCLOCKWISE AROUND THE CENTRAL PORTION OF THE FORECAST RESULTING IN SOME AREAS RECEIVING AN ELONGATED PERIOD OF MODERATE TO BRIEF HEAVY SNOW THIS EVENING. WITH THE CURRENT TRACK OF THE SURFACE LOW...NOT EXPECTING THIS BAND TO DRIFT SOUTHEAST ALL THAT MUCH UNTIL EARLY WEDNESDAY MORNING. GENERALLY EXPECTING A HALF TO POSSIBLY ONE INCH PER HOUR SNOWFALL RATES THIS EVENING WITH THE WEAK LIFT IN THE DENDRITIC LAYER. SREF 100MB/50MB DENDRITE GROWTH ZONE PARAMETER DEPICTING 80-90 PERCENT PROBABILITY OF DENDRITIC SNOW THROUGH TOMORROW AND MATCHES UP WELL WITH PREVIOUSLY MENTION BAND PIVOTING ACROSS CENTRAL IOWA. BUFR SOUNDINGS REMAIN DEEPLY SATURATED THROUGH WEDNESDAY MORNING...WITH THE RAP SHOWING A MID LEVEL DRY LAYER ADVECTING INTO DSM TO ALO AND MAY SEE A BRIEF BREAK IN THE SNOW MID TO LATE EVENING. WINDS ATOP THE MIXED LAYER RANGE FROM 25 TO 30KTS THIS AFTERNOON AND TONIGHT AND EXPECTING BLOWING SNOW IMPACTS TO CONTINUE AS WELL. LEANED TOWARDS THE GFS/SREF QPF AMOUNTS TONIGHT AS NAM SEEMS TO HIGH ACROSS THE EAST...ESPECIALLY WITH THE WEAKER FORCING. .LONG TERM /WEDNESDAY THROUGH TUESDAY/... WEAKER LIFT WILL PERSIST INTO WEDNESDAY WITH THE SPC SREF INDICATING DEEP DENDRITIC GROWTH LAYER CONTINUING THROUGH CENTRAL IOWA. ALL SOUNDINGS CONTINUE TO ALSO SHOW DEEP SATURATION THROUGH AT LEAST MIDDAY TOMORROW AND ANTICIPATE THE LIGHT SNOW TO CONTINUE. HAVE GONE WITH LIKELY TO CATEGORICAL POPS FOR MUCH OF THE AREA UNDER THE CURRENT HEADLINE WITH THE SHARP CUTOFF ON THE NORTHERN SIDE OF THE PCPN AREA PERSISTING. WINDS WILL REMAIN RATHER STRONG THROUGH THE DAY WITH BRISK NORTHWEST FLOW PERSISTING WITH DECENT PRESSURE GRADIENT. EVENTUALLY...THE FORCING WILL BE DIMINISHING WITH THE SNOW TAPERING TO FLURRIES BY LATER IN THE DAY. CLOUDINESS IS EXPECTED TO PERSIST AS WELL IN CYCLONIC FLOW ON BACKSIDE INTO WEDNESDAY NIGHT WITH AN APPROACHING SHORTWAVE ON THURSDAY AND THURSDAY NIGHT HELPING THE CLOUDINESS TO MAINTAIN. IN FACT...SOME WEAK LIFT WITH THIS PASSING WAVE ON FRIDAY MAY HELP TO PRODUCE SOME FLURRIES IN SOUTHERN IOWA DURING THE DAY. UPPER RIDGING WILL SLIDE THROUGH THE REGION INTO THE WEEKEND WITH QUIET WEATHER DURING THIS TIME. TEMPERATURES WILL REMAIN BELOW NORMAL WITH WIDESPREAD SNOW PACK AND ONLY WEAK ADVECTION UNTIL SUNDAY NIGHT. THIS WARM ADVECTION IS IN ADVANCE OF THE NEXT SYSTEM WHICH WILL PASS THROUGH THE REGION ON MONDAY INTO TUESDAY IN BROAD NORTHWEST FLOW. BOTH GFS AND EURO HAVE INDICATED SOME DECENT FORCING AND ANTICIPATE PCPN DEVELOPING AND SLIDING ACROSS THE STATE ON MONDAY INTO EARLY TUESDAY. SOUNDINGS WOULD INDICATE GENERALLY SNOW DURING THIS TIME ACROSS THE STATE WITH LIGHT TO MODERATE ACCUMULATIONS EXPECTED. && .AVIATION...26/18Z AREAS OF LIGHT TO MODERATE SNOW WILL CONTINUE TO IMPACT THE KDSM/KOTM/KALO AREAS THROUGH TONIGHT. A MIX OF MVFR TO IFR STRATUS WILL ACCOMPANY THE SNOW. KFOD AND KMCW WILL HAVE LESS SNOW THOUGH PERIODS OF MVFR STRATUS OR LOWER ARE POSSIBLE AT TIMES. GUSTY NORTHERLY WINDS WILL PREVAIL THROUGH WEDNESDAY && .DMX WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL NOON CST WEDNESDAY FOR ADAIR-ADAMS- APPANOOSE-BLACK HAWK-BOONE-CLARKE-DALLAS-DAVIS-DECATUR-GRUNDY- HARDIN-JASPER-LUCAS-MADISON-MAHASKA-MARION-MARSHALL-MONROE-POLK- POWESHIEK-RINGGOLD-STORY-TAMA-TAYLOR-UNION-WAPELLO-WARREN-WAYNE. WINTER WEATHER ADVISORY UNTIL NOON CST WEDNESDAY FOR AUDUBON- BREMER-BUTLER-CASS-FRANKLIN-GREENE-GUTHRIE-HAMILTON. && $$ SHORT TERM...PODRAZIK LONG TERM...COGIL AVIATION...DONAVON
AREA FORECAST DISCUSSION
NWS TOPEKA KS
509 AM CST MON FEB 25 2013 .DISCUSSION... SEE PREV DISCUSSION. && .AVIATION... THE 09Z RAP AND 06Z NAM HAVE BEEN SHOWING DRY LOW LEVEL AIR ENTRAINING FROM THE NORTHEAST THROUGH MUCH OF THE DAY TODAY. ADDITIONALLY THE GFS AND NAM DO NOT BRING THE TROWAL WITH THE HEAVIEST SNOWFALL INTO THE TERMINALS UNTIL AFTER 00Z. THEREFORE EXPECT VFR CONDITIONS TO PREVAIL TODAY AND HAVE PUSHED BACK THE IFR CIGS AND VSBY WITH -SN UNTIL THIS EVENING. WOLTERS && .PREV DISCUSSION... /402 AM CST MON FEB 25 2013/ FORECAST IS STILL ON TRACK FOR A POTENT WINTER SYSTEM...EXPECTED TO AFFECT THE AREA WITH MODERATE TO HEAVY SNOW AND STRONG WINDS MONDAY THROUGH INTO TUESDAY. A VERY VIGOROUS MID LEVEL TROUGH IS CURRENTLY EVIDENT ON WATER VAPOR IMAGERY AS IT SPINS ACROSS EASTERN NEW MEXICO INTO FAR WESTERN TEXAS. THE TRACK OF THIS WAVE WILL LIKELY RUN ALONG THE RED RIVER TO NEAR DFW BEFORE NEGATIVELY TILTING AND EJECTING NORTHEASTWARD THROUGH OKLAHOMA INTO NW ARKANSAS. RADAR TRENDS SHOW INCREASING REFLECTIVITY RETURNS FROM ACROSS WESTERN OKLAHOMA AND TEXAS...INDICATING MORE INTENSE PRECIP WITH ACCOMPANYING THUNDER. ALSO EVIDENT ON RADAR IS A DEFORMATION BAND TAKING SHAPE ACROSS SOUTH CENTRAL KANSAS...EXTENDING NORTHEASTWARD INTO NORTH CENTRAL AND NORTHEAST KANSAS. THIS DEFORMATION BAND WILL KICK OFF THE PRECIPITATION EXPECTED FROM THIS WINTER STORM ACROSS THE REGION. SURFACE OBSERVATIONS INDICATE ABOVE FREEZING TEMPS IN NORTHEAST AND EAST CENTRAL KANSAS...AND AT OR BELOW FREEZING IN CENTRAL AND NORTH CENTRAL KANSAS. EXPECT THE LIGHT PRECIP TO FALL AS LIGHT SNOW...OR PERHAPS SOME LIGHT FREEZING RAIN...WITH MINOR TO NO ICE ACCUMULATION. THE AFOREMENTIONED MID LEVEL WAVE IS EXPECTED TO EJECT NORTH/NORTHEAST INTO NORTHWEST ARKANSAS LATER TONIGHT TAKING WITH IT A STRONG PV ANOMALY. THE PV ANOMALY WILL LIKELY TRAVERSE JUST SOUTH OF THE FORECAST AREA. WITH THE LOW AND MID LEVEL TROUGHS EXPECTED TO PASS THROUGH JUST SOUTH OF THE FORECAST AREA COLDER AIR WILL BE ALLOWED TO FILTER IN...ALLOWING FOR A QUICKER COOLING OF THE THERMAL PROFILE THROUGHOUT THE DAY. AREAS ALONG AND NORTH/NORTHWEST OF THE KANSAS TURNPIKE WILL LIKELY GO STRAIGHT TO SNOW AS THE COLUMN SATURATES...WITH AREAS SOUTH/SOUTHEAST OF THE TURNPIKE LIKELY HOLDING ONTO A PERIOD OF LIGHT RAIN/FREEZING RAIN THROUGH THE DAYTIME HOURS ON MONDAY. WITH SURFACE TEMPS HAVING A TOUGH TIME GETTING BELOW FREEZING WHERE LIGHT RAIN IS EXPECTED ITS UNLIKELY AT THIS TIME FOR FREEZING RAIN TO PRODUCE ANY KIND OF ACCUMULATION. BY MID DAY FORECAST SOUNDINGS VIRTUALLY ACROSS THE ENTIRE AREA INDICATE A GRADUAL MOISTENING OF THE THERMAL COLUMN AS IT COOLS. ISENTROPIC SURFACES ALONG THE 290 TO 305 K SURFACES INDICATE THAT THE EASTERN HALF OF THE CWA...TOWARD TOP/LWC/MCI WILL TAKE A WHILE TO OVERCOME THE DRY AIR...AS CONDENSATION PRESSURE DEFICITS REMAIN AROUND 50 TO 100 MB UNTIL ABOUT 21Z. RIGHT NOW PEGGING BETWEEN 21Z AND 00Z AS A LIKELY START TIME FOR LIGHT SNOW TO COMMENCE ALONG AND SOUTH OF INTERSTATE 70. BY 00Z GFS/NAM INDICATE A VERY IMPRESSIVE TROWAL SIGNATURE WITH CONDENSATION PRESSURE DEFICITS NEAR 0 ALONG THE PREVIOUSLY MENTIONED ISENTROPIC SURFACES INDICATING STRONG ISENTROPIC ASCENT AND SATURATION. AROUND 00Z NAM/GFS ALSO SHOW OFF A VERY IMPRESSIVE AND PRONOUNCED PERIOD OF LOW AND MID LEVEL FRONTOGENESIS...MAINLY SOUTHEAST OF A LINE BETWEEN HIAWATHA AND COUNCIL GROVE. DURING THIS TIME OF ENHANCED LOW/MID LEVEL FRONTOGENESIS THE COLUMN BECOMES SATURATED THROUGH THE DENDRITIC GROWTH ZONE...INDICATING EFFICIENT SNOWFALL IN FAR NE AND EC KANSAS. CONCURRENT WITH THE STRONG FRONTOGENESIS IS AN AREA OF WEAKENED STABILITY...INDICATED BY A RIBBON OF EPV AROUND -.5 TO -1.0 PVU...JUST ABOVE THE MAIN FRONTOGENESIS BULLS EYE. GIVEN THIS PERIOD OF POTENTIAL CONVECTIVE DEVELOPMENT (00Z TO 09Z TUESDAY) THE POTENTIAL EXISTS FOR HEAVY SNOWFALL IN EAST CENTRAL KANSAS WITH 1 TO POTENTIALLY 3 INCH PER HOUR RATES. BY 12Z TUESDAY THE FRONTOGENESIS AND EPV INFLUENCES MOVE OFF TO THE EAST...AND LIGHT SNOW MAY PERSIST WITHIN THE DEPARTING TROWAL THROUGH 12Z-18Z TUESDAY. REGARDING SNOW AMOUNTS...THE FORECAST REMAINS VERY TRICKY AS THERE WILL LIKELY BE A PRETTY TIGHT GRADIENT BETWEEN THE HIGHEST AMOUNTS IN EC KANSAS AND THE NORTHERN/WESTERN PERIPHERY OF THE SNOW ACCUMULATIONS. ALTHOUGH MODEL CONSENSUS ON GENERAL TRACK OF THE SYSTEM REMAINS PRETTY DECENT THE SLIGHTEST SHIFT IN ANY DIRECTION WOULD BRING UNEXPECTED TOTALS TO AREAS ALONG THE PERIPHERY OF THE SNOW SWATH. OBTAINED SNOW AMOUNTS FOR THIS FORECAST BY TAKING A GENERAL CONSENSUS OF MODEL QPF AND TONING IT BACK TO ABOUT 75 PERCENT OF ITS OUTPUT. WHEN MULTIPLIED BY SNOW RATIOS RANGING FROM 12-15:1 THROUGHOUT THE EVENT THE FINAL SNOW FALL FORECAST FOR THIS EVENT MATERIALIZED. GENERALLY EXPECT A 10-13 INCH SWATH TO FORM ACROSS EAST CENTRAL KANSAS...DECREASING RATHER RAPIDLY TO THE NORTH AND WEST...TO AROUND 10 INCHES IN TOP/LWC...AND 7-9 INCHES IN MHK...ABILENE...AND HIAWATHA...AND 3-5 INCHES ACROSS NORTH CENTRAL KANSAS. WAS TEMPTED TO LOWER AMOUNTS EVEN MORE IN THE EASTERN ZONES...CONSIDERING THE POSSIBILITY OF THE SYSTEM CREEPING EVEN FURTHER SOUTH/EAST...BUT 00Z 4KM WRF INDICATED THAT THE TROWAL PORTION OF THE SYSTEM MAY RESIDE OVER THE AREA...PRODUCING LIGHT TO MODERATE SNOW THROUGH POTENTIALLY TUESDAY NIGHT...BRINGING EVEN MORE ACCUMULATION. A TIGHTENING SURFACE LOW PRESSURE GRADIENT WILL CAUSE WINDS OUT OF THE NORTH/NORTHEAST TO INCREASE THROUGHOUT THE DAY...AND INTO TONIGHT...PRODUCING STRONG WINDS APPROACHING 20 TO 25 MPH WITH GUSTS NEARING 35 MPH. MODEL SOUNDINGS INDICATE STRONG LOW LEVEL WINDS APPROACHING 50 KTS...BUT WITH LOW LEVEL LAPSE RATES NOT BEING EXTREMELY STEEP DO NOT EXPECT ENOUGH MIXING TO ALLOW THOSE WINDS TO REACH THE SURFACE...THEREFORE TRUE BLIZZARD CONDITIONS ARE NOT EXPECTED...HOWEVER THE STRONG WINDS CONCURRENT WITH THE HEAVIEST SNOW WILL LIKELY BRING A PERIOD OF NEAR WHITE OUT CONDITIONS BETWEEN 00Z AND 012Z TUESDAY MORNING. AS A RESULT OF THIS FORECAST...WILL LEAVE THE HEADLINES ALONE AND LET THE UPCOMING DAY SHIFT ASSESS THE SYSTEM AND MAKE THE DECISION TO TWEAK THE WARNING/ADVISORY AREA. MID RANGE TO EXTENDED FORECAST (WEDNESDAY THROUGH SUNDAY)... COLD AIR WILL LIKELY STAY IN PLACE THROUGH THE REST OF THE FORECAST PERIOD...AS A BROAD SURFACE HIGH SLIDES INTO PLACE. ANOTHER WEAK TROUGH WILL COME THROUGH THE AREA ON WEDNESDAY AND MAY SQUEEZE OUT A LITTLE BIT OF MOISTURE TO PRODUCE SOME VERY LIGHT SNOW FALL WITH PERHAPS ANOTHER FEW TENTHS OF AN INCH OF ACCUMULATION. AFTER WEDNESDAY THE FORECAST LOOKS DRY WITH COOL TEMPERATURES IN THE MID 30S TO LOWER 40S REMAIN THROUGH THE WEEK/WEEKEND. JL && .TOP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 6 AM MONDAY TO NOON CST TUESDAY FOR KSZ012-023-024-026-038>040-054>056-058-059. WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR KSZ008-009- 020. WINTER STORM WARNING UNTIL NOON CST TUESDAY FOR KSZ021-022- 034>037. WINTER WEATHER ADVISORY FROM 6 AM MONDAY TO NOON CST TUESDAY FOR KSZ010-011. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1036 PM EST TUE FEB 26 2013 .SYNOPSIS... AN UPPER LEVEL LOW WILL PUSH INTO THE AREA OVERNIGHT...BRINGING A WINTRY MIX OF PRECIPITATION TO THE AREA. COLDER AIR ALOFT WILL THEN BRING A MIX OF RAIN AND SNOW SHOWERS TO THE AREA FOR THE REMAINDER OF THE WORK WEEK. && .NEAR TERM /THROUGH WEDNESDAY/... AN ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO ACCOUNT FOR THE LATEST RADAR AND SATELLITE TRENDS AS A DRY SLOT WORKS INTO THE RIDGES OF WV/MD/PA. THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A CLOSED LOW CENTERED ACROSS SOUTHERN ILLINOIS. 500MB VORT ENERGY IS SLIDING AROUND THE LOW AND INTO THE UPPER OHIO VALLEY WHILE DRIER AIR ALOFT BEGINS TO ADVECT FROM THE SOUTH INTO THE WV APPALACHIANS. 850MB ANALYSIS INDICATES A WARM WEDGE OF 3-4C EXTENDING FROM NORTHERN WV INTO SOUTHERN INDIANA COUNTY PENNSYLVANIA WITH A LOCALIZED AREA WITH TEMPS 0-1C NORTHWEST OF PITTSBURGH. AT THE SURFACE...A 998MB LOW IS CENTERED ACROSS THE OH/IN BORDER WITH AN OCCLUDED FRONT EXTENDING FROM THIS FEATURE EASTWARD TO THE MASON-DIXON LINE. 00Z KPIT SOUNDING INDICATED A FREEZING 900-750MB LAYER WITH TEMPS DROPPING TO -2C IN THE LAYER. ABOVE 750MB...THE MELTING LAYER HAS WEAKENED...ONLY AROUND 1C. THIS SOUNDING WAS CONFIRMED EARLIER FROM DUAL POLARIZATION RADAR REFLECTIVITY...CORRELATION COEFFICIENT...AND DIFFERENTIAL REFLECTIVITY WHICH INDICATED AREAS OF PREDOMINATELY SLEET WITH SNOW MIXING IN FOR THE PITTSBURGH METRO AND AREAS NORTHWARD THIS EVENING. ALONG THE I-80 CORRIDOR...WET BULBING BROUGHT TEMPS DOWN TO NEAR FREEZING AND THEY REMAIN STEADY THERE WITH AN EASTERLY LOW-LEVEL FLOW. THUS...POCKETS OF FREEZING RAIN HAVE BEEN REPORTED THERE. PRECIPITATION HAS MOSTLY COME TO AN END FOR THE LAUREL HIGHLANDS AND ALLEGHENY FRONT AS THE DRY SLOT FINALLY WORKS INTO THE AREA. OVERNIGHT...THE RAP/WRF-NMM INDICATE THE CLOSED LOW WILL SLIDE NORTHEASTWARD ALONG THE OHIO RIVER...BECOMING CENTERED OVER THE NORTHERN PANHANDLE OF WV BY 12Z WEDNESDAY. MEANWHILE...THE SURFACE LOW WILL PUSH NORTHWARD INTO SOUTHERN MICHIGAN WITH THE OCCLUDED FRONT EDGING SLOWLY NORTHEASTWARD INTO THE AREA. PRECIPITATION WILL BE MORE FOCUSED NORTH OF PITTSBURGH AND ACROSS EASTERN OHIO AS THE VORT LIFTS INTO THAT AREA. WRF SIMULATED GOES-R ABI SATELLITE IMAGERY HINTS THAT A DRY SLOT WILL MOSTLY DIMINISH PRECIP FOR LOCATIONS SOUTH AND WEST OF PITTSBURGH OVERNIGHT. 850MB WARM WEDGE OF AIR WILL BECOME PINCHED OFF AS IT SLIDES INTO NORTH- CENTRAL PA AND THE COLD POOL ASSOCIATED WITH THE UPPER LOW ADVECT INTO THE AREA FROM THE SOUTHWEST. WITH THIS IN MIND...SFC TEMPS ARE CLOSE TO A HRRR/LAMP BLEND...REMAINING IN THE LOWER TO MID 30S ACROSS THE AREA. IN ADDITION...THE WEDGE PINCHING OFF WILL ALLOW FOR A WINTRY MIX TO CONTINUE NORTH OF PITTSBURGH AND FOR THE LAUREL HIGHLANDS/ALLEGHENY FRONT...WITH SNOW BEGINNING TO MIX IN WITH RAIN SHOWERS SOUTHWEST OF PITTSBURGH BY DAWN. SNOW/SLEET ACCUMULATIONS WILL BE LESS THAN AN INCH NORTH AND EAST OF PITTSBURGH WITH ADDITIONAL LIGHT ICE ACCUMULATIONS WHERE TEMPS ARE SUB-FREEZING. WEDNESDAY...THE UPPER LOW WILL BECOME MORE ELONGATED AS IT EXTENDS FROM SOUTHERN MICHIGAN INTO CENTRAL PA. THUS...COLD POOL ALOFT WILL SUPPORT SNOW SHOWERS MIXING IN WITH RAIN EARLY. RAIN WILL MIX BACK IN AS 1000-850MB LAYER WARMS ABOVE FREEZING. WITH SURFACE TEMPS MOSTLY ABOVE FREEZING...THIS WILL LIMIT DAYTIME SNOWFALL ACCUMULATIONS ACROSS THE AREA DESPITE VORT ENERGY SUPPORTING A BROAD AREA OF LIFT PUSHING INTO THE AREA EARLY IN THE DAY. HIGH TEMPS UNDERCUT A MAV/MET BLEND BY 3-5 DEGREES AS CLOUD COVERAGE LIMITS TEMPS. HIGHS WILL RANGE FROM THE UPPER 30S TO LOWER 40S ACROSS MUCH OF THE AREA. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... MATURE/STACKED AND COLD LOW PRES WL WOBBLE ACROSS THE REGION THROUGH THURSDAY...AND DIG OFF THE COAST BY FRIDAY ACCORDING TO THE LATEST MDL SOLNS. SCT TO NMRS SHSN WL THUS CONT TO PLAGUE THE REGION FOR THE SHORT TERM PD...WITH UPSLOPE COMPONENT OF WIND ENHANCING SN POTENTIAL IN THE RIDGES. OVRALL ACCUMULATION POTENTIAL WL BE RETARDED OVR AREAS WHERE DAYTIME TEMPS RISE ABOVE FREEZING...SO HEADLINE POTENTIAL IS LIMITED. THE EXCEPTION MAY BE FOR THE RIDGES WHERE PROLONGED SHSN MAY REQUIRE A COUPLE-DAY ADVISORY. FOR NOW...WL MENTION IN THE HAZARDOUS WEATHER OUTLOOK AND TASK FUTURE SHIFTS TO MONITOR. SHORT TERM TEMPS WERE FORECAST CLOSER TO COOLER GFS GUIDANCE. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ECMWF AND GFS CONT TO INDICATE DEVELOPMENT OF AN ERN NORTH AMERICAN TROF FOR THE LONG TERM PD. THE EXTENDED FORECAST THUS CONTINUES TO FEATURE SUB AVERAGE TEMPS AND NR CLIMO...I.E. CHC POPS DEPENDANT ON SPPRTG SHRTWV ENERGY FOR THE INTIAL PDS. SHRTWV RIDGE IN ADVN OF MIDWRN LOW SHOULD REDUCE THOSE POPS BY MONDAY...BUT THAT REPRIEVE LOOKS TO BE BRIEF AS PCPN FM THAT SYSTEM IS CURRENTLY TIMED FOR A TUE INITIATION OVR THE UPR OH VALLEY. && .AVIATION /04Z WEDNESDAY THROUGH SUNDAY/... LOW CONFIDENCE FORECAST. AS OF 03Z...PRECIPITATION HAS BECOME MORE SCATTERED ACROSS TERMINALS. FKL/DUJ MAY REMAIN COLD ENOUGH FOR SNOW...BUT RAIN AT OTHER LOCATIONS SHOULD BE ALL RAIN. DRY SLOT MOVING IN FROM WEST VIRGINIA HAS MANAGED TO BRING VFR CIGS...WHILE FKL/DUJ CURRENTLY REMAIN IFR. FKL/DUJ COULD EVENTUALLY LIFT...BUT EVEN NEWEST MODEL GUIDANCE STILL SAYS THAT CONDITIONS SHOULD CURRENTLY BE IFR. THINK THAT CIGS WILL COME BACK DOWN EVENTUALLY...BUT DO NOT HAVE A GOOD IDEA AT ALL AS TO WHEN THAT WILL HAPPEN. AT THIS POINT...HAVE BROUGHT CONDITIONS DOWN TO MVFR AT 06Z...BUT DO NOT HAVE MUCH CONFIDENCE IN THIS TIMING. MVFR CIGS IN -RA DOMINATE WED...WITH PRECIPITATION EXPECTED TO REMAIN SNOW AT FKL/DUJ. WITH 00Z TAFS...HAVE ADDED GUSTS TO 15-20 KTS IN ADDITION TO THE SW WINDS AROUND 10 KTS. .OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/... BRIEF IFR RESTRICTIONS ARE POSSIBLE IN MODERATE RAIN OR SNOW SHOWERS THROUGH FRIDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...WINTER WEATHER ADVISORY UNTIL 1 AM EST WEDNESDAY FOR PAZ008- 009-015-016. WV...NONE. && $$ SYNOPSIS...WOODRUM NEAR TERM...WOODRUM AVIATION...TGREEN
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
804 PM EST TUE FEB 26 2013 .SYNOPSIS... AN UPPER LEVEL LOW WILL PUSH INTO THE AREA OVERNIGHT...BRINGING A WINTRY MIX OF PRECIPITATION TO THE AREA. COLDER AIR ALOFT WILL THEN BRING A MIX OF RAIN AND SNOW SHOWERS TO THE AREA FOR THE REMAINDER OF THE WORK WEEK. && .NEAR TERM /THROUGH WEDNESDAY/... AN EVENING ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO EXTEND THE WINTER WEATHER ADVISORY NORTHEAST OF PITTSBURGH TO 06Z AND TO PROLONG THE MENTION OF SLEET AND SNOW MIXING IN WITH RAIN NORTH OF I-70. THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A CLOSED LOW CENTERED ACROSS SOUTHERN ILLINOIS. 500MB VORT ENERGY IS SLIDING AROUND THE LOW AND INTO THE UPPER OHIO VALLEY WHILE DRIER AIR ALOFT BEGINS TO ADVECT FROM THE SOUTH INTO THE WV APPALACHIANS. 850MB ANALYSIS INDICATES A WARM WEDGE OF 3-4C EXTENDING FROM NORTHERN WV INTO SOUTHERN INDIANA COUNTY PENNSYLVANIA WITH A LOCALIZED AREA WITH TEMPS 0-1C NORTHWEST OF PITTSBURGH. AT THE SURFACE...A 998MB LOW IS CENTERED ACROSS THE OH/IN BORDER WITH AN OCCLUDED FRONT EXTENDING FROM THIS FEATURE EASTWARD TO THE MASON-DIXON LINE. 00Z KPIT SOUNDING INDICATES A FREEZING 900-750MB LAYER WITH TEMPS DROPPING TO -2C IN THE LAYER. ABOVE 750MB...THE MELTING LAYER HAS WEAKENED...ONLY AROUND 1C. THIS SOUNDING HAS BEEN CONFIRMED FROM DUAL POLARIZATION RADAR REFLECTIVITY...CORRELATION COEFFICIENT...AND DIFFERENTIAL REFLECTIVITY WHICH HAVE INDICATED AREAS ARE OF PREDOMINATELY SLEET WITH SNOW MIXING IN FOR THE PITTSBURGH METRO AND AREAS NORTHWARD THIS EVENING. ALONG THE I-80 CORRIDOR...WET BULBING BROUGHT TEMPS DOWN TO NEAR FREEZING AND THEY REMAIN STEADY THERE WITH AN EASTERLY LOW-LEVEL FLOW. THUS...POCKETS OF FREEZING RAIN HAVE BEEN REPORTED THERE. THE LAUREL HIGHLANDS AND ALLEGHENY FRONT HAVE CONTINUED TO HAVE MOSTLY FREEZING RAIN IN THE WARM WEDGE...ALTHOUGH PRECIPITATION IS BECOMING LIGHTER THERE AS A DRY SLOT FINALLY WORKS INTO THE AREA. OVERNIGHT...THE RAP/WRF-NMM INDICATE A CLOSED LOW WILL SLIDE NORTHEASTWARD ALONG THE OHIO RIVER...BECOMING CENTERED OVER THE NORTHERN PANHANDLE OF WV BY 12Z WEDNESDAY. MEANWHILE...THE SURFACE LOW WILL PUSH NORTHWARD INTO SOUTHERN MICHIGAN WITH THE OCCLUDED FRONT EDGING SLOWLY NORTHEASTWARD INTO THE AREA. PRECIPITATION WILL BE MORE FOCUSED NORTH OF PITTSBURGH AND ACROSS EASTERN OHIO AS THE VORT LIFTS INTO THAT AREA. WRF SIMULATED GOES-R ABI SATELLITE IMAGERY HINTS THAT A DRY SLOT WILL MOSTLY DIMINISH PRECIP FOR LOCATIONS SOUTH AND WEST OF PITTSBURGH OVERNIGHT. 850MB WARM WEDGE OF AIR WILL BECOME PINCHED OFF AS IT SLIDES INTO NORTH- CENTRAL PA AND THE COLD POOL ASSOCIATED WITH THE UPPER LOW ADVECT INTO THE AREA FROM THE SOUTHWEST. WITH THIS IN MIND...SFC TEMPS ARE CLOSE TO A HRRR/LAMP BLEND...REMAINING IN THE LOWER TO MID 30S ACROSS THE AREA. IN ADDITION...THE WEDGE PINCHING OFF WILL ALLOW FOR A WINTRY MIX TO CONTINUE NORTH OF PITTSBURGH AND FOR THE LAUREL HIGHLANDS/ALLEGHENY FRONT...WITH SNOW BEGINNING TO MIX IN WITH RAIN SHOWERS SOUTHWEST OF PITTSBURGH BY DAWN. SNOW/SLEET ACCUMULATIONS WILL BE LESS THAN AN INCH NORTH AND EAST OF PITTSBURGH WITH ADDITIONAL LIGHT ICE ACCUMULATIONS WHERE TEMPS ARE SUB-FREEZING. WEDNESDAY...THE UPPER LOW WILL BECOME MORE ELONGATED AS IT EXTENDS FROM SOUTHERN MICHIGAN INTO CENTRAL PA. THUS...COLD POOL ALOFT WILL SUPPORT SNOW SHOWERS MIXING IN WITH RAIN EARLY. RAIN WILL MIX BACK IN AS 1000-850MB LAYER WARMS ABOVE FREEZING. WITH SURFACE TEMPS MOSTLY ABOVE FREEZING...THIS WILL LIMIT DAYTIME SNOWFALL ACCUMULATIONS ACROSS THE AREA DESPITE VORT ENERGY SUPPORTING A BROAD AREA OF LIFT PUSHING INTO THE AREA EARLY IN THE DAY. HIGH TEMPS UNDERCUT A MAV/MET BLEND BY 3-5 DEGREES AS CLOUD COVERAGE LIMITS TEMPS. HIGHS WILL RANGE FROM THE UPPER 30S TO LOWER 40S ACROSS MUCH OF THE AREA. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... MATURE/STACKED AND COLD LOW PRES WL WOBBLE ACROSS THE REGION THROUGH THURSDAY...AND DIG OFF THE COAST BY FRIDAY ACCORDING TO THE LATEST MDL SOLNS. SCT TO NMRS SHSN WL THUS CONT TO PLAGUE THE REGION FOR THE SHORT TERM PD...WITH UPSLOPE COMPONENT OF WIND ENHANCING SN POTENTIAL IN THE RIDGES. OVRALL ACCUMULATION POTENTIAL WL BE RETARDED OVR AREAS WHERE DAYTIME TEMPS RISE ABOVE FREEZING...SO HEADLINE POTENTIAL IS LIMITED. THE EXCEPTION MAY BE FOR THE RIDGES WHERE PROLONGED SHSN MAY REQUIRE A COUPLE-DAY ADVISORY. FOR NOW...WL MENTION IN THE HAZARDOUS WEATHER OUTLOOK AND TASK FUTURE SHIFTS TO MONITOR. SHORT TERM TEMPS WERE FORECAST CLOSER TO COOLER GFS GUIDANCE. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ECMWF AND GFS CONT TO INDICATE DEVELOPMENT OF AN ERN NORTH AMERICAN TROF FOR THE LONG TERM PD. THE EXTENDED FORECAST THUS CONTINUES TO FEATURE SUB AVERAGE TEMPS AND NR CLIMO...I.E. CHC POPS DEPENDANT ON SPPRTG SHRTWV ENERGY FOR THE INTIAL PDS. SHRTWV RIDGE IN ADVN OF MIDWRN LOW SHOULD REDUCE THOSE POPS BY MONDAY...BUT THAT REPRIEVE LOOKS TO BE BRIEF AS PCPN FM THAT SYSTEM IS CURRENTLY TIMED FOR A TUE INITIATION OVR THE UPR OH VALLEY. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... LOW CONFIDENCE FORECAST. AS OF 00Z...DRY SLOT OF PRECIPITATION IS MOVING INTO SOUTHWEST PENNSYLVANIA...WHICH SHOULD GIVE MOST TERMINALS AT LEAST A TEMPORARY BREAK IN PRECIP. HOWEVER...WHERE PRECIPITATION REMAINS...ALL PRECIPITATION TYPES HAVE BEEN REPORTED. HAVE STUCK WITH RAIN IN THE TAFS THROUGH MUCH OF THE NIGHT EXCEPT AT DUJ...WHERE FREEZING RAIN MAY PERSIST. DRY SLOT COULD ALSO WRECK HAVOC ON CEILING FORECASTS TONIGHT. GUIDANCE INDICATES IFR/LIFR CONDITIONS DEVELOPING...WHILE VFR CIGS ARE MOVING IN WITH THE DRY SLOT. HAVE SPLIT THE BALANCE AT THIS POINT...GENERALLY KEEPING ALL CIGS MVFR. AS TEMPERATURES DECREASE...HAVE DROPPED FKL/DUJ TO SNOW WITH LIFR CIGS. MVFR CIGS IN -RA DOMINATE WED...WITH PRECIPITATION EXPECTED TO REMAIN SNOW AT FKL/DUJ. WITH 00Z TAFS...HAVE ADDED GUSTS TO 15-20 KTS IN ADDITION TO THE SW WINDS AROUND 10 KTS. .OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/... BRIEF IFR RESTRICTIONS ARE POSSIBLE IN MODERATE RAIN OR SNOW SHOWERS THROUGH FRIDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR MDZ001. OH...NONE. PA...WINTER WEATHER ADVISORY UNTIL 1 AM EST WEDNESDAY FOR PAZ008- 009-015-016-023. WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR PAZ074-076. WV...WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR WVZ023- 041. && $$ SYNOPSIS...WOODRUM NEAR TERM...WOODRUM AVIATION...TGREEN
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
653 PM EST TUE FEB 26 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 428 PM EST TUE FEB 26 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW PRONOUNCED SPLIT FLOW CONTINUING ACROSS NAMERICA. IN WHAT HAS BEEN A VERY ACTIVE SRN STREAM RECENTLY...A WELL-DEFINED MID LEVEL LOW IS MOVING ENE INTO THE LWR OHIO VALLEY. SRN STREAM RIDGING AHEAD OF FEATURE EXTENDS FROM JUST OFF THE SE COAST TO SRN NEW ENGLAND AND THEN BACK INTO THE UPPER LAKES. WITH NRN STREAM WELL N OF HERE...ARCTIC AIR HAS RETREATED INTO NRN CANADA. CLOSER TO HOME...PESKY STRATOCU HAS CONTINUED TO PLAGUE UPPER MI TODAY. HOWEVER...ROUGHLY THE W THIRD OF THE FCST AREA HAS ENJOYED MOSTLY SUNNY SKIES FOR AT LEAST A PORTION OF THE DAY. THE POCKET OF MOSTLY SUNNY SKIES CURRENTLY OVER THE W IS SHOWING SIGNS OF EXPANDING EASTWARD AS STRONGER DAYTIME HEATING UNDER HIGHER LATE FEB SUN ANGLE IS WORKING ON LOWER ALBEDO FORESTED TERRAIN TO RAISE MIXED LAYER AND THUS MIX OUT THE SHALLOW MOIST LAYER. DURING THE SHORT TERM...MAIN FCST ISSUE WILL REVOLVE AROUND NORTHWARD PROGESS OF A WEAKENING PCPN SHIELD SPREADING N AROUND SRN STREAM MID LEVEL LOW AS IT TRACKS INTO THE UPPER OHIO VALLEY/LWR LAKES REGION. EARLY ON...LOW CLOUDS WILL CONTINUE TO PRESENT SOME ISSUES. CLEARING MAY CONTINUE TO EXPAND E FROM WRN UPPER MI OVER THE NEXT COUPLE OF HRS...BUT WITH LOSS OF DAYTIME HEATING...STRATOCU WILL PROBABLY TEND TO SPREAD BACK INTO THE AREAS THAT HAVE CLEARED...ESPECIALLY IF THE STRATOCU TO THE E AND NE DOES NOT BREAK UP DURING THE LATE AFTN/EVENING. LATEST VIS SATELLITE IMAGERY DOES SHOW STRATOCU THINNING OVER ERN LAKE SUPERIOR...SO THERE MAY YET BE SOME MORE CLEARING DURING THE EVENING. WILL BE A TREND TO MONITOR. WHILE CLOUDS WILL AGAIN MAKE OR BREAK TEMP FCST...THERE WILL LIKELY NOT BE AS GREAT OF A TEMP SPREAD TONIGHT AS IN PREVIOUS NIGHTS BTWN AREAS WITH CLOUDS AND AREAS WITH LESS CLOUD SINCE INCREASING GRADIENT WINDS WILL LIMIT RADIATIONAL COOLING. TRENDED TEMPS TOWARD RAW MODEL GUIDANCE WHICH PUTS MIN TEMPS GENERALLY IN THE MID/UPPER 20S. AS FOR PCPN...THE STRONG ISENTROPIC ASCENT COMPONENT TO PCPN SHIELD SPREADING N INTO SRN WI/SRN MI ATTM WILL GRADUALLY FADE WITH TIME AS THE ZONE OF STRONG ASCENT TRANSLATES EASTWARD...RESULTING IN ZONE OF HEAVIEST PCPN SHIFTING E TOWARD THE LWR LAKES/SRN NEW ENGLAND TONIGHT/WED MORNING. THUS...A DECAYING SHIELD OF PCPN WILL BE LIFTING TOWARD UPPER MI TONIGHT/WED MORNING. RECENT MODEL TRENDS GENERALLY POINT TOWARD A MORE AGGRESSIVE PUSH OF LIGHT SNOW INTO UPPER MI. GIVEN THE STRONG NORTHWARD PUSH OF PCPN THRU LWR MI ATTM AND THE LACK OF A LAYER OF VERY DRY AIR AT THE LOWER LEVELS TO THE N ACROSS UPPER MI...HAVE OPTED TO TREND PCPN CHC SLIGHTLY FARTHER N THAN PREVIOUS FCST TO ROUGHLY A KERY/KSAW/KIMT LINE AND RAISED POPS TO HIGH CHC ALONG LAKE MI. WITH 850MB TEMPS NO LWR THAN -8/-9C... IT`S VERY UNLIKELY THAT ANY LES WILL DEVELOP OFF LAKE SUPERIOR UNDER STRONG NE CYCLONIC FLOW WED. IF SHIELD OF LIGHT SYNOPTIC SNOW DOES REACH LAKE SUPERIOR...THEN A LITTLE LAKE COMPONENT WILL BE THERE. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 428 PM EST TUE FEB 26 2013 LITTLE CHANGES TO THE LONG TERM FROM 24 HOURS AGO...WITH THE MAIN ITEM OF DIFFERENCE A SLIGHT WOBBLE TO THE NORTHWEST WITH THE SYSTEM CURRENTLY MOVING THROUGH THE MID MISSISSIPPI VALLEY THAT WILL MOVE THROUGH THE LOWER GREAT LAKES. THIS SLIGHT ADJUSTMENT...PUSHES THE PRECIPITATION A TOUCH FARTHER INLAND FROM LAKE MICHIGAN. BUT AS THE LONG TERM PERIOD BEGINS...THE LOW WILL START IT/S EASTWARD SHIFT TOWARDS NEW YORK AND DIMINISH THE SNOW ALONG THE LAKE MICHIGAN SHORELINE. ATTENTION THEN TURNS TO THE AMOUNT OF MOISTURE AND COLD AIR IN THE LOWER LEVELS TO SUPPORT LAKE ENHANCED AND UPSLOPE SNOW SHOWERS. LATEST TRENDS IN THE MOISTURE AND COLD AIR /850MB TEMPERATURES FALLING FROM -9C AT WEDNESDAY NIGHT TO -13C BETWEEN 900-850MB BY THURSDAY AFTERNOON/ LEADS TO GREATER CONFIDENCE IN SCATTERED SNOW SHOWERS OCCURRING FOR LOCATIONS NEAR LAKE SUPERIOR FROM PICTURED ROCKS AND WESTWARD. INVERSION HEIGHTS AROUND 3-4KFT SHOULD KEEP THE INTENSITY IN CHECK AND HELPS KEEP LAKE INDUCED CAPES BELOW 200 J/KG. THUS...WILL BUMP POPS UP 5-10 PERCENT INTO HIGHER END CHANCE CATEGORY. SNOWFALL AMOUNTS SHOULD BE FAIRLY LIGHT...SINCE CLOUD DEPTH IS FAIRLY LIMITED. WITH THE INITIAL CLOUD LAYER MAINLY BEING BELOW THE DGZ WEDNESDAY NIGHT...WOULD EXPECT FLAKES TO BE FAIRLY SMALL. BUT AS THE COLDER AIR ARRIVES...IT DOES ATTEMPT TO PUSH THE CLOUD LAYER INTO THE DGZ AND HELP SNOW RATIOS. BUT WITH THE LIMITED CLOUD DEPTH/MOISTURE TO WORK WITH...WOULDN/T EXPECT MUCH MORE THAN AN INCH OR TWO OF TOTAL ACCUMULATION BY THE TIME IT STARTS WINDING DOWN ON FRIDAY. THE HIGHEST AMOUNTS WILL BE IN THE FAVORED UPSLOPE LOCATIONS WITH NORTHEAST WINDS...ESPECIALLY IN/NEAR THE HURON MOUNTAINS WHICH COULD APPROACH 3 INCHES. A BUILDING CANADIAN HIGH OVER HUDSON BAY WILL SLIDE A RIDGE SOUTH INTO THE UPPER GREAT LAKES REGION FRIDAY AND IT WILL REMAIN INTO THE FIRST PART OF THE NEXT WEEK. THIS WILL WORK TO REDUCE THE INVERSION HEIGHTS TO 2KFT AND SHOULD BRING AN END TO THE LAKE ENHANCED/EFFECT BY FRIDAY NIGHT. WILL GO WITH PARTLY CLOUDY SKIES THROUGH THE WEEKEND...BUT THERE IS SOME CONCERN THAT THERE COULD BE LINGERING LOW CLOUDS BELOW THE STRENGTHENING INVERSION DURING THAT TIME. MAIN QUESTION FOR NEXT WEEK WILL BE THE LOCATION OF A SHORTWAVE CUTTING THROUGH THE UPPER RIDGE OVER THE WESTERN CONUS AND IT/S INFLUENCE ON THE UPPER TROUGH ON THE EAST COAST. 00Z ECMWF HOLDS THE TROUGH OVER THE AREA...WHILE THE GFS TRIES TO PUSH THE RIDGE OVER THE AREA ON MONDAY. THIS HAS THE POTENTIAL FOR WEAKENING THE SURFACE RIDGE AND PUSHING SOME PRECIPITATION INTO THE AREA ON THE EAST SIDE OF A LOW MOVING THROUGH CENTRAL PLAINS OR UPPER MISSISSIPPI VALLEY. WILL RESPECT THE CONSISTENCY SHOWN IN THE ECMWF OVER THE LAST SEVERAL DAYS AND TRY TO KEEP MUCH OF THE AREA DRY. HIGH TEMPERATURES ARE STILL LOOKING TO BE BELOW NORMAL THROUGH THE LONG TERM PERIOD. LOOKING AT THE LONGER RANGE FORECASTS /EVEN THOUGH SKILL IS FAIRLY LIMITED/...NOT TOO MANY SIGNS OF SPRING FOR THE FIRST WEEK OR TWO OF MARCH. GFS/ECMWF ENS MEANS ARE SHOWING 850MB TEMPS BELOW NORMAL THROUGH THE FIRST WEEK AND GFS ENS 500MB MEAN HEIGHTS ARE SHOWING A TROUGH REMAINING OVER THE EASTERN CONUS THROUGH THE MIDDLE OF MARCH. AFTER BEING SPOILED BY WARM MARCH WEATHER IN 2010/2012...ITS LOOKING LIKE MARCH WILL BE MORE TRADITIONAL TEMPERATURE WISE. UNFORTUNATELY FOR SOME OF THE LOCATIONS OF CENTRAL UPPER MICHIGAN THAT HAVE SEEN PROLONGED DRYNESS...THIS PATTERN WON/T BE SUPPORTIVE OF ANY SIGNIFICANT PRECIPITATION AND MAINLY JUST LIGHT PRECIPITATION FROM CLIPPERS. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 652 PM EST TUE FEB 26 2013 DEVELOPING UPSLOPE NE FLOW AT KIWD SHOULD LEAD TO MVFR CLOUDS MOVING BACK IN LATE TONIGHT AFT 09Z AND THEN PERSISTING THROUGH WEDNESDAY. DEVELOPING DOWNSLOPE NE FLOW AT KCMX SHOULD LEAD TO MVFR DECK DISSIPATING LATER THIS EVENING. CONTINUING NE FLOW SHOULD MAINTAIN VFR CONDITIONS THRU WEDNESDAY WITH SOME INCREASE IN MID-LVL CLOUDS EXPECTED WITH APPROACH OF MOISTURE FM SYSTEM OVER THE LOWER LAKES. NE UPSLOPE FLOW SHOULD MAINTAIN MVFR CONDITIONS AT KSAW THROUGH THE FCST PD. TIGHTENING PRES GRADIENT WILL LEAD TO AN INCREASE IN NE WIND GUSTS AOA 25 KTS ON WEDNESDAY. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 428 PM EST TUE FEB 26 2013 TIGHTENING PRES GRADIENT BTWN HIGH PRES TO THE N AND NW AND LOW PRES TRACKING THRU THE LWR OHIO VALLEY TO LWR LAKES WILL RESULT IN NORTHEASTERLY WINDS ACROSS LAKE SUPERIOR INCREASING TO 20-30KT TONIGHT THRU WED. MIGHT SEE A FEW GALE FORCE GUSTS WED AFTN OVER THE E HALF. EVEN THOUGH THE LOW CONTINUES TO MOVE E THU...THE HIGH BUILDING TOWARD THE AREA FROM N WILL MAINTAIN A TIGHT PRES GRADIENT...RESULTING IN CONTINUED 20-30KT WINDS WITH SOME GALE FORCE GUSTS POSSIBLE OVER THE E HALF THRU THU MORNING. WINDS WILL THEN VERY SLOWLY DIMINISH FROM W TO E FRI/SAT AS THE HIGH PRES MOVES CLOSER...BUT IT WILL PROBABLY BE SAT BEFORE WINDS DROP BLO 20KT ACROSS THE ENTIRE LAKE. THE PERIOD OF STRONG WINDS WED NIGHT THRU FRI WILL ALSO BRING THE POTENTIAL FOR FREEZING SPRAY. LIGHT WINDS UNDER 10KT ARE EXPECTED SUN AS SFC HIGH PRES RIDGE WILL EXTEND FROM HUDSON BAY S ACROSS LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...SRF AVIATION...VOSS MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
414 PM EST MON FEB 25 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 413 PM EST MON FEB 25 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A SPLIT FLOW PATTERN ACROSS NAMERICA. IN THE SRN STREAM...A WELL-DEFINED MID LEVEL LOW WAS OVER N TX. IN THE NRN STREAM...A SHORTWAVE TROF EXTENDS FROM HUDSON BAY TO THE UPPER MISSISSIPPI VALLEY. SOME FLURRIES HAVE BEEN NOTED IN WI TODAY IN AN AREA OF WEAK ISENTROPIC ASCENT. SOME OF THOSE FLURRIES MAY HAVE SLIPPED INTO SCTNRL UPPER MI THIS AFTN ALTHOUGH NO REPORTS HAVE BEEN NOTED. OTHERWISE...MOSTLY CLOUDY SKIES HAVE BEEN THE RULE TODAY...THOUGH THERE WAS A PERIOD OF MOSTLY SUNNY SKIES FOR A TIME EARLIER OVER THE FAR W AND NW. ALTHOUGH THE SHORT TERM PORTION OF THE FCST WILL FEATURE TRANQUIL WEATHER...CLOUDS AND TEMPS WILL OFFER SOME CHALLENGING ASPECTS TO THE FCST. UNDER WEAK ISENTROPIC ASCENT...WILL MAINTAIN A MENTION OF A FEW FLURRIES INTO THE EVENING HRS OVER THE SRN PORTION OF THE FCST AREA. CLOUD FCST IS NOT CERTAIN AT ALL AND THAT OPENS THE DOOR TO BIG TEMP BUST POTENTIAL TONIGHT. UNDER LIGHT SW FLOW INTO THE EVENING...MULTI-LAYERED CLOUDS TO THE SW SHOULD AFFECT MUCH OF THE FCST AREA. OVERNIGHT...LOW-LEVEL WIND FIELDS BECOME VERY LIGHT WITH A TREND TO LIGHT EASTERLY LATE WHICH SUGGESTS LITTLE ADVECTION OF DRIER AIR. THUS...IT WOULD SEEM THAT MUCH OF THE AREA WILL SEE MOSTLY CLOUDY SKIES TONIGHT. HOWEVER...THE PROXIMITY OF CLEAR SKIES JUST TO THE W SUGGESTS THE WRN FCST AREA MAY HAVE THE BEST SHOT OF SEEING A PERIOD OF PARTLY CLOUDY AND POSSIBLY CLEAR SKIES TONIGHT. ALL IN ALL...THERE IS VERY LOW CONFIDENCE ON SKY CONDITION THRU THE NIGHT. WITH LIGHT/CALM WINDS AT THE SFC...TEMPS WILL FALL SIGNIFICANTLY IN SOME AREAS IF SKIES BECOME CLEAR/PARTLY CLOUDY FOR A TIME. THIS COULD ALSO LEAD TO SOME FOG DEVELOPMENT. AT THIS POINT...WILL PLAY IT CONSERVATIVE UTILIZING A CONSENSUS APPROACH TO TEMPS...BUT WILL GO WITH LOWEST MIN TEMPS OVER THE W (MID TEENS) WHERE IT APPEARS THERE IS A BETTER SHOT OF SEEING LESS CLOUDS FOR AT LEAST A PORTION OF THE NIGHT. COULD EASILY SEE TEMPS FALL INTO THE SINGLE DIGITS IF ANY LOCATIONS END UP CLEAR FOR A FEW HRS. E TO NE WINDS WILL DEVELOP TUE AS UPPER MI FALLS INTO THE NRN PERIPHERY OF THE CIRCULATION AROUND SRN STREAM LOW. WINDS WILL BE STRONGEST IN THE MENOMINEE AREA AS A STIFF NE WIND WILL BE THE RULE IN THE AFTN DUE TO COASTAL CONVERGENCE/FUNNELING DOWN THE BAY. STRATOCU SHOULD TEND TO BREAK UP AS MODELS SUGGEST SOME DRYING... BUT THE LWR CLOUDS WILL PROBABLY HANG ON LONGEST WHERE EASTERLY WINDS UPSLOPE. WHERE LOW CLOUDS SCATTER OUT OR CLEAR...THERE SHOULD BE A FAIR AMOUNT OF SUNSHINE THRU ONLY SOME HIGH CLOUDS. EXPECT MAX TEMPS IN THE 30S...COOLEST (LOW 30S) AT LOCATIONS WHERE WINDS ARE OFF THE LAKES AND IN THE UPSLOPE AREAS. TEMPS COULD RISE TO NEAR 40 IN LOCATIONS THAT SEE DOWNSLOPING WITH EASTERLY WINDS. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 413 PM EST MON FEB 25 2013 THREE SHORTWAVES WILL INFLUENCE THE WEATHER FOR MUCH OF THE EASTERN HALF OF THE CONUS OVER THE NEXT SEVERAL DAYS AND SETUP THE WEATHER PATTERN HEADING INTO THE FIRST WEEK OF MARCH. THE FIRST WAVE IS CURRENTLY SPINNING IN THE SOUTHERN PLAINS AND WILL EJECT TOWARDS THE LOWER GREAT LAKES ON TUESDAY INTO TUESDAY NIGHT...WHILE THE NEXT WAVE DIVES SOUTHEAST ACROSS THE CENTRAL ROCKIES. MODELS HAVE BECOME MUCH MORE CONSISTENT WITH THIS SYSTEM IN THE LAST 24 HOURS...AS THERE WERE DIFFERENCES IN THE INTERACTION BETWEEN THE FIRST AND SECOND WAVES...WITH THE MERGER AND NORTHWARD EXTENT. EVERYTHING SEEMS TO HAVE COME INTO AGREEMENT WITH THE CONSISTENT ECMWF ON A MORE SOUTHERN TRACK THAT JUST BRUSHES THE FAR SOUTHEAST PART OF UPPER MICHIGAN /NEAR LAKE MICHIGAN/ WITH LIGHT SNOW LATE TUESDAY NIGHT INTO WEDNESDAY EVENING. ANY SLIGHT DIFFERENCES IN THE NORTHWEST EXTENT OF THE TRACK WILL NOT ONLY AFFECT THE SNOW NEAR LAKE MICHIGAN...BUT ALSO THE POTENTIAL FOR LIGHT LAKE ENHANCEMENT OR UPSLOPE PRECIPITATION WITH THE NORTH-NORTHEAST FLOW AROUND THE LOW. WITH THE LIMITED COLD AIR IN PLACE AT THIS TIME...IT LOOKS LIKE 850MB TEMPS ON WEDNESDAY ARE ONLY AROUND -5C...SO DELTA-T VALUES ARE FAIRLY MARGINAL. WHEN COMBINING THAT WITH LIMITED MOISTURE...UNLESS THE FARTHER NW 06Z NAM IS CORRECT...WOULDN/T THINK AREAS AWAY FROM LAKE MICHIGAN WOULD SEE MUCH MORE THAN LOW CLOUDS AND UPSLOPE FLURRIES OR LIGHT SNOW OVER THE NORTH CENTRAL ON WEDNESDAY PENDING ENOUGH MOISTURE. MODELS ARE IN BETTER AGREEMENT ON LOW LEVEL MOISTURE MOVING IN ON WEDNESDAY NIGHT AS THE LOW SHIFTS EAST INTO NEW YORK. THIS IS IN RESPONSE TO ADDITIONAL MOISTURE ASSOCIATED WITH A NORTHERN STREAM SHORTWAVE MOVING THROUGH SOUTHERN CANADA. THIS WILL LIKELY LEAD TO THE BEST POTENTIAL FOR PRECIPITATION FOR AREAS NEAR LAKE SUPERIOR WEDNESDAY NIGHT INTO THURSDAY. 850MB TEMPS ARE STILL MARGINAL THROUGH THIS PERIOD...BUT DO DROP TO -10C. WITH THE MARGINAL DELTA-T VALUES AND AN INVERSION HEIGHT SITTING AROUND 4KFT...THINKING THAT THE LIGHT SNOW SHOWERS WILL REMAIN IN THE NORTH-NORTHEAST FAVORED LOCATIONS OF NORTHERN UPPER MICHIGAN. STRONGEST SHOWERS SHOULD OCCUR OVER THE HIGHER TERRAIN OF NORTH CENTRAL UPPER MICHIGAN...WHERE UPSLOPE FLOW WILL AID THE FORCING SOME. WILL CONTINUE TO MENTION SLIGHTS AND LOW CHANCE POPS IN THESE AREAS INTO THURSDAY NIGHT. MEANWHILE...THE THIRD MAIN SHORTWAVE WILL BE DIVING SOUTHEAST THROUGH THE ROCKIES ON WEDNESDAY NIGHT AND THURSDAY AND AMPLIFY THE UPPER TROUGH OVER THE EASTERN CONUS. THIS WILL LEAD THE UPPER GREAT LAKES INTO A COLDER THAN NORMAL PERIOD FOR THE LAST DAY OF FEBRUARY AND THE FIRST WEEK OF MARCH. WHILE THIS BRINGS GRADUALLY COLDER AIR /925-900MB TEMPS FALLING TOWARDS -12 TO -14C/...IT WILL ALSO PUSH A HIGH PRESSURE RIDGE OVER THE AREA FROM A HIGH CENTERED OVER HUDSON BAY. THIS SUBSIDENCE WILL WORK TO LOWER THE INVERSION HEIGHTS BELOW 3KFT BY FRIDAY MORNING. THEREFORE...WOULD JUST EXPECT LINGERING LOW CLOUDS AND AN ISOLATED SNOW SHOWER FOR FRIDAY INTO SATURDAY OVER LOCATIONS NEAR LAKE SUPERIOR. THERE ARE SOME DIFFERENCES IN THE WIND DIRECTION ROTATING AROUND THE HIGH...BUT WILL MAINLY FOCUS THE SLIGHT CHANCES OVER THE NORTH CENTRAL. DIFFERENCES ARRIVE HEADING INTO THE SECOND HALF OF THE WEEKEND WITH THE HANDLING OF A SHORTWAVE DROPPING THROUGH ON THE BACK SIDE OF THE RIDGE OVER THE WESTERN CONUS. THE 00Z ECMWF KEEPS THE RIDGE FARTHER TO THE WEST BEHIND THE SHORTWAVE...WHILE THE 12Z GFS PUSHES IT INTO THE UPPER GREAT LAKES. DEPENDING ON THE SOLUTION...THIS WILL EITHER KEEP THE AREA UNDER THE SURFACE RIDGE INTO THE FIRST PART OF NEXT WEEK OR HAVE THE AREA INFLUENCED BY THE NEXT CLIPPER SYSTEM APPROACHING FOR MONDAY. WILL GO WITH THE PERSISTENT HIGH AND DRIER SOLUTION INTO MONDAY. AFTER A FAIRLY ACTIVE PERIOD FOR THE LAST COUPLE OF WEEKS OF FEBRUARY...IT/S LOOKING LIKE MARCH WILL COME IN LIKE A LAMB FOR MUCH OF THE UPPER GREAT LAKES REGION. FORTUNATELY...THIS ACTIVE PERIOD BROUGHT THE AREA CLOSER TO NORMAL SNOWFALL...ALTHOUGH SOME LOCATIONS ARE STILL BELOW NORMAL ON SNOWFALL /OUR OFFICE/ AND SNOW WATER EQUIVALENT /MICHIGAMME RIVER BASIN/. BUT LOOKING AT MODEL RUN QPF...THE NEXT 10 DAYS DON/T APPEAR TO BE TOO PROMISING FOR ADDITIONS TO THE SNOW PACK. 00Z ECMWF ONLY SHOWS 10 DAY ACCUMULATION OF 0.02-0.08 INCH FOR THE ENTIRE CWA. 00Z GFS FOR THE SIMILAR PERIOD KEEPS VALUES UNDER 0.25 OF AN INCH...WITH MUCH OF THAT COMING FROM THE SYSTEM BRUSHING THE AREA ON WEDNESDAY AND THURSDAY. ON THE POSITIVE SIDE...THE EXISTING SNOWPACK WILL REMAIN IN PLACE AS TEMPERATURES TREND TOWARDS A COOLER THAN NORMAL PERIOD FOR THE AREA FRIDAY INTO THE NEXT WORK WEEK /HIGHS IN THE 20S AND LOWS IN THE SINGLE DIGITS ABOVE ZERO/. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1237 PM EST MON FEB 25 2013 VFR CONDITIONS SHOULD PREVAIL THRU THE FCST PERIOD AT KIWD/KCMX... THOUGH PROXIMITY OF LOWER CIGS JUST TO THE S AND SW MAY RESULT IN MVFR CIGS DEVELOPING AT KIWD AND PERHAPS AT KCMX THIS AFTN/EVENING. SHOULD SKIES CLEAR TONIGHT...FOG AND POSSIBLE IFR CONDITIONS COULD DEVELOP AT KIWD/KCMX. AT KSAW...HIGH MVFR CIGS ARE LIKELY TO PREVAIL INTO THE EVENING GIVEN UPSTREAM MVFR CIGS. IF CLOUDS SCATTER OUT LATER TONIGHT...IFR CONDITIONS COULD ALSO DEVELOP AT KSAW. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 413 PM EST MON FEB 25 2013 ALTHOUGH HIGH PRES WILL BE DEPARTING...WINDS WILL REMAIN UNDER 20KT PROBABLY THRU TUE AFTN. THEREAFTER...TIGHTENING PRES GRADIENT BTWN HIGH PRES TO THE N AND NW AND LOW PRES TRACKING THRU THE LOWER OHIO VALLEY TO LOWER LAKES TUE/WED WILL RESULT IN NORTHEASTERLY WINDS INCREASING TO 20-30KT TUE NIGHT THRU WED. MIGHT SEE A FEW GALE FORCE GUSTS WED OVER THE E HALF. EVEN THOUGH THE LOW CONTINUES TO MOVE E THU...THE HIGH BUILDING TOWARD THE AREA FROM N WILL MAINTAIN A TIGHT PRES GRADIENT...RESULTING IN CONTINUED 20-30KT WINDS WITH SOME GALE FORCE GUSTS POSSIBLE OVER THE E HALF. WINDS WILL THEN VERY SLOWLY DIMINISH FROM W TO E FRI/SAT AS THE HIGH PRES MOVES CLOSER... BUT IT WILL PROBABLY BE SAT BEFORE WINDS DROP BLO 20KT ACROSS THE ENTIRE LAKE. ALONG WITH THE PERIOD OF STRONGER WINDS MID WEEK...FREEZING SPRAY IS ALSO EXPECTED. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...SRF AVIATION...ROLFSON MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1239 PM EST MON FEB 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 337 AM EST MON FEB 25 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW DOMINATING THE FLOW OVER NAMERICA. RDG IN THE NRN BRANCH IS PRESENT FM JAMES BAY INTO THE UPR GRT LKS TO THE W OF DEPARTING CLOSED LO IN SE CANADA/NEW ENGLAND...AND A SFC HI PRES RDG EXTENDS FM NE ONTARIO THRU ECENTRAL UPR MI INTO THE UPR MIDWEST. WITH DRY AIR AOA H8 AS SHOWN ON 00Z APX/GRB RAOBS AND LARGER SCALE SUBSIDENCE UNDER THE RDG...THERE IS NO PCPN IN THE AREA. EVEN LES IS ABSENT WITH LLVL ACYC FLOW AND H85 TEMPS -6C AT INL AND GRB. DESPITE PASSAGE OF SFC RDG AXIS...QUITE A BIT OF LO CLD LINGERS WITH SOME MSTR/RELATIVELY HI SFC DEWPTS TRAPPED BLO SUBSIDENCE INVRN H825-875 SHOWN ON THE 00Z APX/GRB RAOBS. SOME CLRG HAS OCCURRED OVER THE W AND NEAR THE WI BORDER INTO NE MN/NRN WI...WHERE SOME LLVL DRY AIR SHOWN ON THE 00Z GRB/MPX RAOBS HAS SHIFTED TO THE N. WHERE SKIES HAVE CLRD...TEMPS FELL OFF SHARPLY IN THE PRESENCE OF NEAR CALM WINDS. SOME PATCHY FOG/ST HAS ALSO DVLPD...SO THE CLRG HOLES ARE IN SOME CASES SHORT LIVED. ALTHOUGH THERE ARE MORE HOLES IN THE LO CLDS OVER FAR NRN WI/NE MN...MORE LO/MID CLDS ARE STREAMING NEWD INTO CNTRL MN/WI IN THE LLVL SW FLOW BTWN RDG AXIS OVER UPR MI AND LO PRES TROF EXTENDING FM LK WINNIPEG INTO THE NRN PLAINS ASSOCIATED WITH PAIR OF NRN BRANCH DISTURBANCES. A POTENT DISTURBANCE IN THE THE SRN BRANCH IS PRESENT OVER THE SRN ROCKIES. MAIN FCST CONCERNS IN THE SHORT TERM ARE TRICKY CLD TRENDS/IMPACT ON TEMPS. DESPITE SOME DIURNAL HEATING FM INCRSG SUN ANGLE AND SW FLOW ON THE BACK SIDE OF HI PRES THAT WL ELIMINATE ANY LK SUP INFLUENCE AND ADVECT SOME DRIER AIR THAT HAS CAUSED CLRG OVER NW WI...RECENT TRENDS INDICATE LO CLDS MIGHT PROVE QUITE RESILIENT OVER THE CWA WITH MORE MORE LO CLDS TENDING TO FORM OVER NRN WI. THE WINDOW FOR CLRG WL BE RELATIVELY SHORT AS WELL BECAUSE BOTH 00Z NAM/GFS INDICATE CLDS NOW STREAMING NEWD TOWARD CENTRAL WI AHEAD OF PAIR OF SLOWLY APRCHG NRN BRANCH DISTURBANCES WL ARRIVE AT THE WI BORDER LATER THIS MRNG. INCLUDED A MENTION OF FLURRIES OVER THE SCENTRAL THIS AFTN WITH SOMEWHAT DEEPER MSTR UNDER AREA OF WEAK DEEP LYR QVECTOR CNVGC. WITH ABUNDANT CLD COVER MORE LIKELY...WL TEND TOWARD THE LOWER END OF GUIDANCE FOR MAX TEMPS...WHICH IS IN GOOD AGREEMENT WITH GOING FCST. EXPECT THE HIER MAX TEMPS OVER THE NCENTRAL FM BARAGA-MQT WHERE LLVL SSW FLOW DOWNSLOPES. TNGT...AS PAIR OF NRN BRANCH SHRTWVS SHIFT E INTO THE UPR LKS... GUIDANCE SHOWS THESE DISTURBANCES FADING UNDER LARGER SCALE HGT RISES ASSOCIATED WITH BLDG UPR RDG ON NRN FLANK OF STRONGER SRN BRANCH DISTURBANCE MOVING INTO THE MID-MS RIVER VALLEY. ALTHOUGH LLVL FLOW TENDS ACYC...WINDS ARE FCST TO BE LGT. SO RATHER MOIST LLVLS WL BE LINGERING IN THE ABSENCE OF SGNFT LLVL DRYING. THE QUESTION IS WHETHER LARGER SCALE SUBSIDENCE WL RESULT IN THE BREAK UP OF THIS LO CLD. IN THE ABSENCE OF SGNFT LLVL DRYING AND IN THE PRESENCE OF DIURNAL COOLING...SUSPECT THE RESULT WL BE LINGERING LO CLDS THRU THE NGT WITH SUBSIDENCE STRENGTHENING THE INVRN THAT TRAPS THIS MSTR. CONSIDERING THE UNCERTAINTY...MADE FEW CHGS TO GOING MIN TEMPS FCST. IF THE LO CLDS ARE MORE PERSISTENT...FCST MIN TEMPS IN THE UPR TEENS/LO 20S WL HAVE TO BE RAISED. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 337 AM EST MON FEB 25 2013 UPPER MICHIGAN LOOK TO BE TAKING A BREAK FROM THE MODERATE TO HEAVY SNOW THAT HAS BEEN COMMON PLACE OVER THE PAST WEEK OR SO. THE CURRENT 500MB LOW SWINGING ACROSS NORTHERN TEXAS THIS MORNING SHOULD BE OVER NORTHERN ARKANSAS/SOUTHERN MISSOURI BY 12Z TUESDAY...WITH THE RIDGE EXTENDING FROM THE ATLANTIC BACK THROUGH UPPER MICHIGAN/LAKE SUPERIOR/NORTHERN MINNESOTA. THE 500MB RIDGE WILL BE QUICKLY PUSHED NORTH OF THE AREA DURING THE DAY TUESDAY...WITH THE THEN NEARLY STACKED SFC-500MB SHOULD BE ABLE TO LIFT TO SOUTHERN ILLINOIS/INDIANA. E-ENE WINDS WILL BE ON THE INCREASE ACROSS UPPER MICHIGAN...AND IN PARTICULAR ALONG LAKE MICHIGAN. WITH SURFACE TEMPERATURES IN THE LOW 30S...AND 850MB TEMPS HOVERING AROUND -3C NO LAKE EFFECT SNOW IS EXPECTED. IN FACT...DRY WEATHER SHOULD BE THE RULE THROUGH TUESDAY EVENING. THE 25/00Z NAM IS A STRONGER FAR NORTHERN OUTLIER WITH THE 500MB LOW...BRINGING THE 500MB LOW OVER CENTRAL LOWER MI BY 18Z WEDNESDAY. THE CONSENSUS OF THE GFS/ECMWF/CANADIAN HAS THE FEATURE SOUTH OF DETROIT... NORTHERN OHIO...OR ACROSS NORTHWESTERN PENNSYLVANIA. THE DIVERGENCE OF THE NAM SOLUTION IS MOST DRAMATIC AFTER 00Z WEDNESDAY...AND WILL THEREFORE NOT BE UTILIZED IN OUR ONGOING FORECAST BEYOND THAT POINT. TO A LESSER EXTENT THE CANADIAN BRIDGES THE GAP BETWEEN THE FASTER GFS/ECMWF AND THE NORTHWESTERLY NAM...BUT ENDS UP RUNNING APPROXIMATELY 12HRS BEHIND THE ECMWF BY THURSDAY /AT 500MB ACROSS NEW YORK AND THE NEW ENGLAND STATES. MAY NEED TO ADD FLURRIES FOR UPSLOPE AREAS OF NORTH CENTRAL UPPER MICHIGAN NEAR LAKE SUPERIOR LATE WEDNESDAY AFTERNOON ON. EXPECT A SHORTWAVE TO SWING ACROSS ONTARIO WEDNESDAY NIGHT INTO THURSDAY...BUT HAVE LITTLE INFLUENCE ON OUR WEATHER OTHER THAN KEEPING CLOUDS OVERHEAD. 850MB TEMPS WILL BE ABLE TO DROP TO AROUND -8C THURSDAY AS COOLER AIR PUSHES IN BEHIND THE MAIN LOW. WITH N-NNE WINDS OFF LAKE SUPERIOR THERE WILL BE AN INCREASED CHANCE OF LIGHT LAKE EFFECT SNOW SHOWERS...WITH A SLIGHT INCREASE IN LOW LEVEL MOISTURE...DESPITE A STRONG INVERSION NOTED OFF THE GFS HOVERING NEAR 850MB. THE DGZ LOOKS TO REBOUND...ALTHOUGH THIN /ABOUT 50MB THICK/ LATE WEDNESDAY NIGHT THROUGH SATURDAY MORNING. ANOTHER 500MB RIDGE WILL BE ABLE TO PUSH ACROSS THE UPPER GREAT LAKES THURSDAY THROUGH MUCH OF FRIDAY. EXPECT COOLER AIR TO FILTER IN AGAIN FRIDAY NIGHT...AND TAKE HOLD OF THE UPPER GREAT LAKES BY SUNDAY AS 850MB TEMPS FALL FROM AROUND -10C TO -13 OR -14C. WIND DIRECTION DOES NOT CHANGE MUCH DURING THIS TIME...WITH FAIRLY STEADY N-NE WINDS SLIDING IN OFF LAKE SUPERIOR. AS A RESULT...IT WILL BE DIFFICULT TO TAKE OUT THE MENTION OF LIGHT SNOW SHOWERS NEAR LAKE SUPERIOR /EVEN IF IT IS JUST A SLIGHT CHANCE/...DESPITE THE STRONG SURFACE HIGH STRETCHING FROM NORTHERN HUDSON BAY THROUGH ONTARIO AND PORTIONS OF LAKE SUPERIOR THURSDAY NIGHT THROUGH SUNDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1237 PM EST MON FEB 25 2013 VFR CONDITIONS SHOULD PREVAIL THRU THE FCST PERIOD AT KIWD/KCMX... THOUGH PROXIMITY OF LOWER CIGS JUST TO THE S AND SW MAY RESULT IN MVFR CIGS DEVELOPING AT KIWD AND PERHAPS AT KCMX THIS AFTN/EVENING. SHOULD SKIES CLEAR TONIGHT...FOG AND POSSIBLE IFR CONDITIONS COULD DEVELOP AT KIWD/KCMX. AT KSAW...HIGH MVFR CIGS ARE LIKELY TO PREVAIL INTO THE EVENING GIVEN UPSTREAM MVFR CIGS. IF CLOUDS SCATTER OUT LATER TONIGHT...IFR CONDITIONS COULD ALSO DEVELOP AT KSAW. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 337 AM EST MON FEB 25 2013 A RIDGE OF HIGH PRESSURE JUST EAST OF LAKE SUPERIOR WILL REMAIN OVER THE UPPER GREAT LAKES THROUGH TONIGHT. EXPECT LOW PRESSURE OVER THE SOUTHERN PLAINS TO TRACK NORTHEAST ACROSS THE MID MISSISSIPPI VALLEY ON TUESDAY...BEFORE STALLING OVER THE LOWER GREAT LAKES ON WEDNESDAY. A PROLONGED PERIOD OF N TO NE WINDS CAN BE EXPECTED...WITH WINDS OF 15 TO 30KTS TUESDAY INTO FRIDAY. A FEW GALE FORCE GUSTS TO 35 KNOTS WILL BE POSSIBLE THURSDAY OVER MAINLY CENTRAL LAKE SUPERIOR. THE LOW WILL THEN MOVE EAST THURSDAY THROUGH FRIDAY AS HIGH PRESSURE OF NOSES SOUTHWARD INTO NORTHERN ONTARIO...WITH LIGHTER WINDS TAKING HOLD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...KF AVIATION...ROLFSON MARINE...KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
623 AM EST MON FEB 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 337 AM EST MON FEB 25 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW DOMINATING THE FLOW OVER NAMERICA. RDG IN THE NRN BRANCH IS PRESENT FM JAMES BAY INTO THE UPR GRT LKS TO THE W OF DEPARTING CLOSED LO IN SE CANADA/NEW ENGLAND...AND A SFC HI PRES RDG EXTENDS FM NE ONTARIO THRU ECENTRAL UPR MI INTO THE UPR MIDWEST. WITH DRY AIR AOA H8 AS SHOWN ON 00Z APX/GRB RAOBS AND LARGER SCALE SUBSIDENCE UNDER THE RDG...THERE IS NO PCPN IN THE AREA. EVEN LES IS ABSENT WITH LLVL ACYC FLOW AND H85 TEMPS -6C AT INL AND GRB. DESPITE PASSAGE OF SFC RDG AXIS...QUITE A BIT OF LO CLD LINGERS WITH SOME MSTR/RELATIVELY HI SFC DEWPTS TRAPPED BLO SUBSIDENCE INVRN H825-875 SHOWN ON THE 00Z APX/GRB RAOBS. SOME CLRG HAS OCCURRED OVER THE W AND NEAR THE WI BORDER INTO NE MN/NRN WI...WHERE SOME LLVL DRY AIR SHOWN ON THE 00Z GRB/MPX RAOBS HAS SHIFTED TO THE N. WHERE SKIES HAVE CLRD...TEMPS FELL OFF SHARPLY IN THE PRESENCE OF NEAR CALM WINDS. SOME PATCHY FOG/ST HAS ALSO DVLPD...SO THE CLRG HOLES ARE IN SOME CASES SHORT LIVED. ALTHOUGH THERE ARE MORE HOLES IN THE LO CLDS OVER FAR NRN WI/NE MN...MORE LO/MID CLDS ARE STREAMING NEWD INTO CNTRL MN/WI IN THE LLVL SW FLOW BTWN RDG AXIS OVER UPR MI AND LO PRES TROF EXTENDING FM LK WINNIPEG INTO THE NRN PLAINS ASSOCIATED WITH PAIR OF NRN BRANCH DISTURBANCES. A POTENT DISTURBANCE IN THE THE SRN BRANCH IS PRESENT OVER THE SRN ROCKIES. MAIN FCST CONCERNS IN THE SHORT TERM ARE TRICKY CLD TRENDS/IMPACT ON TEMPS. DESPITE SOME DIURNAL HEATING FM INCRSG SUN ANGLE AND SW FLOW ON THE BACK SIDE OF HI PRES THAT WL ELIMINATE ANY LK SUP INFLUENCE AND ADVECT SOME DRIER AIR THAT HAS CAUSED CLRG OVER NW WI...RECENT TRENDS INDICATE LO CLDS MIGHT PROVE QUITE RESILIENT OVER THE CWA WITH MORE MORE LO CLDS TENDING TO FORM OVER NRN WI. THE WINDOW FOR CLRG WL BE RELATIVELY SHORT AS WELL BECAUSE BOTH 00Z NAM/GFS INDICATE CLDS NOW STREAMING NEWD TOWARD CENTRAL WI AHEAD OF PAIR OF SLOWLY APRCHG NRN BRANCH DISTURBANCES WL ARRIVE AT THE WI BORDER LATER THIS MRNG. INCLUDED A MENTION OF FLURRIES OVER THE SCENTRAL THIS AFTN WITH SOMEWHAT DEEPER MSTR UNDER AREA OF WEAK DEEP LYR QVECTOR CNVGC. WITH ABUNDANT CLD COVER MORE LIKELY...WL TEND TOWARD THE LOWER END OF GUIDANCE FOR MAX TEMPS...WHICH IS IN GOOD AGREEMENT WITH GOING FCST. EXPECT THE HIER MAX TEMPS OVER THE NCENTRAL FM BARAGA-MQT WHERE LLVL SSW FLOW DOWNSLOPES. TNGT...AS PAIR OF NRN BRANCH SHRTWVS SHIFT E INTO THE UPR LKS... GUIDANCE SHOWS THESE DISTURBANCES FADING UNDER LARGER SCALE HGT RISES ASSOCIATED WITH BLDG UPR RDG ON NRN FLANK OF STRONGER SRN BRANCH DISTURBANCE MOVING INTO THE MID-MS RIVER VALLEY. ALTHOUGH LLVL FLOW TENDS ACYC...WINDS ARE FCST TO BE LGT. SO RATHER MOIST LLVLS WL BE LINGERING IN THE ABSENCE OF SGNFT LLVL DRYING. THE QUESTION IS WHETHER LARGER SCALE SUBSIDENCE WL RESULT IN THE BREAK UP OF THIS LO CLD. IN THE ABSENCE OF SGNFT LLVL DRYING AND IN THE PRESENCE OF DIURNAL COOLING...SUSPECT THE RESULT WL BE LINGERING LO CLDS THRU THE NGT WITH SUBSIDENCE STRENGTHENING THE INVRN THAT TRAPS THIS MSTR. CONSIDERING THE UNCERTAINTY...MADE FEW CHGS TO GOING MIN TEMPS FCST. IF THE LO CLDS ARE MORE PERSISTENT...FCST MIN TEMPS IN THE UPR TEENS/LO 20S WL HAVE TO BE RAISED. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 337 AM EST MON FEB 25 2013 UPPER MICHIGAN LOOK TO BE TAKING A BREAK FROM THE MODERATE TO HEAVY SNOW THAT HAS BEEN COMMON PLACE OVER THE PAST WEEK OR SO. THE CURRENT 500MB LOW SWINGING ACROSS NORTHERN TEXAS THIS MORNING SHOULD BE OVER NORTHERN ARKANSAS/SOUTHERN MISSOURI BY 12Z TUESDAY...WITH THE RIDGE EXTENDING FROM THE ATLANTIC BACK THROUGH UPPER MICHIGAN/LAKE SUPERIOR/NORTHERN MINNESOTA. THE 500MB RIDGE WILL BE QUICKLY PUSHED NORTH OF THE AREA DURING THE DAY TUESDAY...WITH THE THEN NEARLY STACKED SFC-500MB SHOULD BE ABLE TO LIFT TO SOUTHERN ILLINOIS/INDIANA. E-ENE WINDS WILL BE ON THE INCREASE ACROSS UPPER MICHIGAN...AND IN PARTICULAR ALONG LAKE MICHIGAN. WITH SURFACE TEMPERATURES IN THE LOW 30S...AND 850MB TEMPS HOVERING AROUND -3C NO LAKE EFFECT SNOW IS EXPECTED. IN FACT...DRY WEATHER SHOULD BE THE RULE THROUGH TUESDAY EVENING. THE 25/00Z NAM IS A STRONGER FAR NORTHERN OUTLIER WITH THE 500MB LOW...BRINGING THE 500MB LOW OVER CENTRAL LOWER MI BY 18Z WEDNESDAY. THE CONSENSUS OF THE GFS/ECMWF/CANADIAN HAS THE FEATURE SOUTH OF DETROIT... NORTHERN OHIO...OR ACROSS NORTHWESTERN PENNSYLVANIA. THE DIVERGENCE OF THE NAM SOLUTION IS MOST DRAMATIC AFTER 00Z WEDNESDAY...AND WILL THEREFORE NOT BE UTILIZED IN OUR ONGOING FORECAST BEYOND THAT POINT. TO A LESSER EXTENT THE CANADIAN BRIDGES THE GAP BETWEEN THE FASTER GFS/ECMWF AND THE NORTHWESTERLY NAM...BUT ENDS UP RUNNING APPROXIMATELY 12HRS BEHIND THE ECMWF BY THURSDAY /AT 500MB ACROSS NEW YORK AND THE NEW ENGLAND STATES. MAY NEED TO ADD FLURRIES FOR UPSLOPE AREAS OF NORTH CENTRAL UPPER MICHIGAN NEAR LAKE SUPERIOR LATE WEDNESDAY AFTERNOON ON. EXPECT A SHORTWAVE TO SWING ACROSS ONTARIO WEDNESDAY NIGHT INTO THURSDAY...BUT HAVE LITTLE INFLUENCE ON OUR WEATHER OTHER THAN KEEPING CLOUDS OVERHEAD. 850MB TEMPS WILL BE ABLE TO DROP TO AROUND -8C THURSDAY AS COOLER AIR PUSHES IN BEHIND THE MAIN LOW. WITH N-NNE WINDS OFF LAKE SUPERIOR THERE WILL BE AN INCREASED CHANCE OF LIGHT LAKE EFFECT SNOW SHOWERS...WITH A SLIGHT INCREASE IN LOW LEVEL MOISTURE...DESPITE A STRONG INVERSION NOTED OFF THE GFS HOVERING NEAR 850MB. THE DGZ LOOKS TO REBOUND...ALTHOUGH THIN /ABOUT 50MB THICK/ LATE WEDNESDAY NIGHT THROUGH SATURDAY MORNING. ANOTHER 500MB RIDGE WILL BE ABLE TO PUSH ACROSS THE UPPER GREAT LAKES THURSDAY THROUGH MUCH OF FRIDAY. EXPECT COOLER AIR TO FILTER IN AGAIN FRIDAY NIGHT...AND TAKE HOLD OF THE UPPER GREAT LAKES BY SUNDAY AS 850MB TEMPS FALL FROM AROUND -10C TO -13 OR -14C. WIND DIRECTION DOES NOT CHANGE MUCH DURING THIS TIME...WITH FAIRLY STEADY N-NE WINDS SLIDING IN OFF LAKE SUPERIOR. AS A RESULT...IT WILL BE DIFFICULT TO TAKE OUT THE MENTION OF LIGHT SNOW SHOWERS NEAR LAKE SUPERIOR /EVEN IF IT IS JUST A SLIGHT CHANCE/...DESPITE THE STRONG SURFACE HIGH STRETCHING FROM NORTHERN HUDSON BAY THROUGH ONTARIO AND PORTIONS OF LAKE SUPERIOR THURSDAY NIGHT THROUGH SUNDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 620 AM EST MON FEB 25 2013 EXPECT VFR CONDITIONS TO PREDOMINATE TODAY WITH DAYTIME HEATING AND ARRIVAL OF LLVL DRY AIR SHOWN ON THE 00Z GRB/MPX RAOBS IN GENERAL SW FLOW. THE ONLY EXCEPTION MAY BE SOME FOG AT SAW EARLY UNDER SMALL AREA OF MOCLR SKIES. CIGS MAY DIP INTO THE MVFR RANGE FOR A TIME TNGT WITH ARRIVAL OF A BIT MORE LLVL MSTR IN THE PRESENCE OF DIURNAL COOLING. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 337 AM EST MON FEB 25 2013 A RIDGE OF HIGH PRESSURE JUST EAST OF LAKE SUPERIOR WILL REMAIN OVER THE UPPER GREAT LAKES THROUGH TONIGHT. EXPECT LOW PRESSURE OVER THE SOUTHERN PLAINS TO TRACK NORTHEAST ACROSS THE MID MISSISSIPPI VALLEY ON TUESDAY...BEFORE STALLING OVER THE LOWER GREAT LAKES ON WEDNESDAY. A PROLONGED PERIOD OF N TO NE WINDS CAN BE EXPECTED...WITH WINDS OF 15 TO 30KTS TUESDAY INTO FRIDAY. A FEW GALE FORCE GUSTS TO 35 KNOTS WILL BE POSSIBLE THURSDAY OVER MAINLY CENTRAL LAKE SUPERIOR. THE LOW WILL THEN MOVE EAST THURSDAY THROUGH FRIDAY AS HIGH PRESSURE OF NOSES SOUTHWARD INTO NORTHERN ONTARIO...WITH LIGHTER WINDS TAKING HOLD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...KF AVIATION...KC MARINE...KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
338 AM EST MON FEB 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 337 AM EST MON FEB 25 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW DOMINATING THE FLOW OVER NAMERICA. RDG IN THE NRN BRANCH IS PRESENT FM JAMES BAY INTO THE UPR GRT LKS TO THE W OF DEPARTING CLOSED LO IN SE CANADA/NEW ENGLAND...AND A SFC HI PRES RDG EXTENDS FM NE ONTARIO THRU ECENTRAL UPR MI INTO THE UPR MIDWEST. WITH DRY AIR AOA H8 AS SHOWN ON 00Z APX/GRB RAOBS AND LARGER SCALE SUBSIDENCE UNDER THE RDG...THERE IS NO PCPN IN THE AREA. EVEN LES IS ABSENT WITH LLVL ACYC FLOW AND H85 TEMPS -6C AT INL AND GRB. DESPITE PASSAGE OF SFC RDG AXIS...QUITE A BIT OF LO CLD LINGERS WITH SOME MSTR/RELATIVELY HI SFC DEWPTS TRAPPED BLO SUBSIDENCE INVRN H825-875 SHOWN ON THE 00Z APX/GRB RAOBS. SOME CLRG HAS OCCURRED OVER THE W AND NEAR THE WI BORDER INTO NE MN/NRN WI...WHERE SOME LLVL DRY AIR SHOWN ON THE 00Z GRB/MPX RAOBS HAS SHIFTED TO THE N. WHERE SKIES HAVE CLRD...TEMPS FELL OFF SHARPLY IN THE PRESENCE OF NEAR CALM WINDS. SOME PATCHY FOG/ST HAS ALSO DVLPD...SO THE CLRG HOLES ARE IN SOME CASES SHORT LIVED. ALTHOUGH THERE ARE MORE HOLES IN THE LO CLDS OVER FAR NRN WI/NE MN...MORE LO/MID CLDS ARE STREAMING NEWD INTO CNTRL MN/WI IN THE LLVL SW FLOW BTWN RDG AXIS OVER UPR MI AND LO PRES TROF EXTENDING FM LK WINNIPEG INTO THE NRN PLAINS ASSOCIATED WITH PAIR OF NRN BRANCH DISTURBANCES. A POTENT DISTURBANCE IN THE THE SRN BRANCH IS PRESENT OVER THE SRN ROCKIES. MAIN FCST CONCERNS IN THE SHORT TERM ARE TRICKY CLD TRENDS/IMPACT ON TEMPS. DESPITE SOME DIURNAL HEATING FM INCRSG SUN ANGLE AND SW FLOW ON THE BACK SIDE OF HI PRES THAT WL ELIMINATE ANY LK SUP INFLUENCE AND ADVECT SOME DRIER AIR THAT HAS CAUSED CLRG OVER NW WI...RECENT TRENDS INDICATE LO CLDS MIGHT PROVE QUITE RESILIENT OVER THE CWA WITH MORE MORE LO CLDS TENDING TO FORM OVER NRN WI. THE WINDOW FOR CLRG WL BE RELATIVELY SHORT AS WELL BECAUSE BOTH 00Z NAM/GFS INDICATE CLDS NOW STREAMING NEWD TOWARD CENTRAL WI AHEAD OF PAIR OF SLOWLY APRCHG NRN BRANCH DISTURBANCES WL ARRIVE AT THE WI BORDER LATER THIS MRNG. WITH ABUNDANT CLD COVER MORE LIKELY...WL TEND TOWARD THE LOWER END OF GUIDANCE FOR MAX TEMPS...WHICH IS IN GOOD AGREEMENT WITH GOING FCST. EXPECT THE HIER MAX TEMPS OVER THE NCENTRAL FM BARAGA-MQT WHERE LLVL SSW FLOW DOWNSLOPES. TNGT...AS PAIR OF NRN BRANCH SHRTWVS SHIFT E INTO THE UPR LKS... GUIDANCE SHOWS THESE DISTURBANCES FADING UNDER LARGER SCALE HGT RISES ASSOCIATED WITH BLDG UPR RDG ON NRN FLANK OF STRONGER SRN BRANCH DISTURBANCE MOVING INTO THE MID-MS RIVER VALLEY. ALTHOUGH LLVL FLOW TENDS ACYC...WINDS ARE FCST TO BE LGT. SO RATHER MOIST LLVLS WL BE LINGERING IN THE ABSENCE OF SGNFT LLVL DRYING. THE QUESTION IS WHETHER LARGER SCALE SUBSIDENCE WL RESULT IN THE BREAK UP OF THIS LO CLD. IN THE ABSENCE OF SGNFT LLVL DRYING AND IN THE PRESENCE OF DIURNAL COOLING...SUSPECT THE RESULT WL BE LINGERING LO CLDS THRU THE NGT WITH SUBSIDENCE STRENGTHENING THE INVRN THAT TRAPS THIS MSTR. CONSIDERING THE UNCERTAINTY...MADE FEW CHGS TO GOING MIN TEMPS FCST. IF THE LO CLDS ARE MORE PERSISTENT...FCST MIN TEMPS IN THE UPR TEENS/LO 20S WL HAVE TO BE RAISED. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 337 AM EST MON FEB 25 2013 UPPER MICHIGAN LOOK TO BE TAKING A BREAK FROM THE MODERATE TO HEAVY SNOW THAT HAS BEEN COMMON PLACE OVER THE PAST WEEK OR SO. THE CURRENT 500MB LOW SWINGING ACROSS NORTHERN TEXAS THIS MORNING SHOULD BE OVER NORTHERN ARKANSAS/SOUTHERN MISSOURI BY 12Z TUESDAY...WITH THE RIDGE EXTENDING FROM THE ATLANTIC BACK THROUGH UPPER MICHIGAN/LAKE SUPERIOR/NORTHERN MINNESOTA. THE 500MB RIDGE WILL BE QUICKLY PUSHED NORTH OF THE AREA DURING THE DAY TUESDAY...WITH THE THEN NEARLY STACKED SFC-500MB SHOULD BE ABLE TO LIFT TO SOUTHERN ILLINOIS/INDIANA. E-ENE WINDS WILL BE ON THE INCREASE ACROSS UPPER MICHIGAN...AND IN PARTICULAR ALONG LAKE MICHIGAN. WITH SURFACE TEMPERATURES IN THE LOW 30S...AND 850MB TEMPS HOVERING AROUND -3C NO LAKE EFFECT SNOW IS EXPECTED. IN FACT...DRY WEATHER SHOULD BE THE RULE THROUGH TUESDAY EVENING. THE 25/00Z NAM IS A STRONGER FAR NORTHERN OUTLIER WITH THE 500MB LOW...BRINGING THE 500MB LOW OVER CENTRAL LOWER MI BY 18Z WEDNESDAY. THE CONSENSUS OF THE GFS/ECMWF/CANADIAN HAS THE FEATURE SOUTH OF DETROIT... NORTHERN OHIO...OR ACROSS NORTHWESTERN PENNSYLVANIA. THE DIVERGENCE OF THE NAM SOLUTION IS MOST DRAMATIC AFTER 00Z WEDNESDAY...AND WILL THEREFORE NOT BE UTILIZED IN OUR ONGOING FORECAST BEYOND THAT POINT. TO A LESSER EXTENT THE CANADIAN BRIDGES THE GAP BETWEEN THE FASTER GFS/ECMWF AND THE NORTHWESTERLY NAM...BUT ENDS UP RUNNING APPROXIMATELY 12HRS BEHIND THE ECMWF BY THURSDAY /AT 500MB ACROSS NEW YORK AND THE NEW ENGLAND STATES. MAY NEED TO ADD FLURRIES FOR UPSLOPE AREAS OF NORTH CENTRAL UPPER MICHIGAN NEAR LAKE SUPERIOR LATE WEDNESDAY AFTERNOON ON. EXPECT A SHORTWAVE TO SWING ACROSS ONTARIO WEDNESDAY NIGHT INTO THURSDAY...BUT HAVE LITTLE INFLUENCE ON OUR WEATHER OTHER THAN KEEPING CLOUDS OVERHEAD. 850MB TEMPS WILL BE ABLE TO DROP TO AROUND -8C THURSDAY AS COOLER AIR PUSHES IN BEHIND THE MAIN LOW. WITH N-NNE WINDS OFF LAKE SUPERIOR THERE WILL BE AN INCREASED CHANCE OF LIGHT LAKE EFFECT SNOW SHOWERS...WITH A SLIGHT INCREASE IN LOW LEVEL MOISTURE...DESPITE A STRONG INVERSION NOTED OFF THE GFS HOVERING NEAR 850MB. THE DGZ LOOKS TO REBOUND...ALTHOUGH THIN /ABOUT 50MB THICK/ LATE WEDNESDAY NIGHT THROUGH SATURDAY MORNING. ANOTHER 500MB RIDGE WILL BE ABLE TO PUSH ACROSS THE UPPER GREAT LAKES THURSDAY THROUGH MUCH OF FRIDAY. EXPECT COOLER AIR TO FILTER IN AGAIN FRIDAY NIGHT...AND TAKE HOLD OF THE UPPER GREAT LAKES BY SUNDAY AS 850MB TEMPS FALL FROM AROUND -10C TO -13 OR -14C. WIND DIRECTION DOES NOT CHANGE MUCH DURING THIS TIME...WITH FAIRLY STEADY N-NE WINDS SLIDING IN OFF LAKE SUPERIOR. AS A RESULT...IT WILL BE DIFFICULT TO TAKE OUT THE MENTION OF LIGHT SNOW SHOWERS NEAR LAKE SUPERIOR /EVEN IF IT IS JUST A SLIGHT CHANCE/...DESPITE THE STRONG SURFACE HIGH STRETCHING FROM NORTHERN HUDSON BAY THROUGH ONTARIO AND PORTIONS OF LAKE SUPERIOR THURSDAY NIGHT THROUGH SUNDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1231 AM EST MON FEB 25 2013 GIVEN FAIRLY LOW DEWPOINT DEPRESSIONS AND THE OBSERVANCE OF PATCHY FOG FORMING OVER NRN WI...HAVE DECIDED TO INCLUDE A MENTION OF MVFR OR EVEN IFR VSBYS IN FOG AT ALL TAF SITES LATER TONIGHT WITH MVFR CIGS. ANY FOG SHOULD LIFT BY LATE MON MORNING AND EXPECT MVFR CLOUDS TO LIFT BY AFTERNOON WITH ADVECTION OF DRIER AIR AT LOW-LVLS IN SW FLOW. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 337 AM EST MON FEB 25 2013 A RIDGE OF HIGH PRESSURE JUST EAST OF LAKE SUPERIOR WILL REMAIN OVER THE UPPER GREAT LAKES THROUGH TONIGHT. EXPECT LOW PRESSURE OVER THE SOUTHERN PLAINS TO TRACK NORTHEAST ACROSS THE MID MISSISSIPPI VALLEY ON TUESDAY...BEFORE STALLING OVER THE LOWER GREAT LAKES ON WEDNESDAY. A PROLONGED PERIOD OF N TO NE WINDS CAN BE EXPECTED...WITH WINDS OF 15 TO 30KTS TUESDAY INTO FRIDAY. A FEW GALE FORCE GUSTS TO 35 KNOTS WILL BE POSSIBLE THURSDAY OVER MAINLY CENTRAL LAKE SUPERIOR. THE LOW WILL THEN MOVE EAST THURSDAY THROUGH FRIDAY AS HIGH PRESSURE OF NOSES SOUTHWARD INTO NORTHERN ONTARIO...WITH LIGHTER WINDS TAKING HOLD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...KF AVIATION...VOSS/KC MARINE...KF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
303 PM CST MON FEB 25 2013 .DISCUSSION... A RATHER BENIGN FORECAST PERIOD IS AHEAD FOR THE LOCAL AREA...AS EYES ARE FOCUSED TO THE SOUTH WITH THE POTENT WINTER STORM UNDERWAY. FOR THE MPX CWA...THE PRIMARY CONCERNS THIS FORECAST PERIOD ARE FOG TONIGHT AND SNOWFALL CHANCES FOR TOMORROW NIGHT INTO WEDNESDAY. FOG AND LOW CLOUDS HAVE BEEN VERY SLOW TO ERODE TODAY...WITH THE LIGHT WINDS AND LOITERING HIGH PRESSURE RIDGE FIRMLY IN PLACE. HAVE FINALLY MADE SOME HEADWAY IN THE CLEARING THIS AFTERNOON...BUT THINK FOG REDEVELOPMENT IS QUITE POSSIBLE AGAIN TONIGHT...ESPECIALLY FROM CENTRAL INTO WEST CENTRAL MN WHERE TEMP/DEWPOINT SPREADS ARE LOW AND WINDS WILL REMAIN LIGHT THROUGH THE NIGHT. HAVE HIGHLIGHTED THE POTENTIAL FOR PATCHY DENSE FOG IN THE HWO AND GRIDS...AND WILL MONITOR FOR THE POTENTIAL NEED FOR AN ADVISORY THIS EVENING AS THE CLEARING EVOLVES. ON TUESDAY...NORTHEAST WINDS INCREASE AS THE AFOREMENTIONED LOW PRESSURE SYSTEM LIFTS ACROSS THE OH VALLEY. ON TUESDAY NIGHT INTO WEDNESDAY...WEAK MID LEVEL ENERGY ON THE NORTHERN/WESTERN PERIPHERY PIVOTS ACROSS CENTRAL WI AND SERN MN. WHILE THE LIFT AND MOISTURE ARE MODEST...COULD BE SUFFICIENT TO SQUEEZE OUT A FEW TENTHS OF AN INCH OF SNOW FROM NEAR ALBERT LEA TOWARD EAU CLAIRE...WHERE SLIGHT CHANCE POPS HAVE BEEN INCLUDED FOR TUESDAY NIGHT AND WEDNESDAY. AFTER THAT...CHANCES FOR MEASURABLE SNOW REALLY DO NOT ARRIVE UNTIL EARLY NEXT WEEK...AS A CLIPPER SYSTEM DIVES SOUTHEAST FROM CANADA. THERE/S STILL A LARGE AMOUNT OF UNCERTAINTY WITH THE ROUTE THIS TROUGH WILL TAKE...BUT WESTERN INTO SOUTH CENTRAL MN APPEARS TO BE THE MORE FAVORED ROUTE FOR LIGHT SNOWFALL ON MONDAY INTO TUESDAY. TEMPERATURES WILL VARY LITTLE THROUGH THE FORECAST PERIOD...WITH HIGHS GENERALLY FROM 25 TO 35...AND LOWS FROM 10 TO 25. && .AVIATION.../18Z TAF ISSUANCE/ VERY COMPLICATED AVIATION FORECAST AS WINDS REMAIN NEARLY CALM UP TO 500 METERS WHICH WILL LIMIT ANY MIXING. THE ONLY HELP THIS AFTN IS THE HIGHER SUN ANGLE ALLOWING FOR BETTER ISOLATION WHICH WILL LEAD TO SOME EROSION IN THE CLOUDS FROM TOP TO BOTTOM. REGIONAL SATELLITE INDICATED THE BACK EDGE OF THE LOW CIGS ALONG THE ND/SD BORDER WITH LITTLE MOVEMENT EASTWARD OVER THE PAST FEW HRS. BASED ON THE LATEST RAP MIX LAYER UP TO 500 METERS...WINDS ARE NEARLY CALM AS EXPLAINED BEFORE WITH A MORE SW ORIENTATION NORTH/NE OF THE FA. A MORE N/NE FLOW ACROSS SW MN WHICH IS HAVING SOME AFFECTS FROM THE STORM SYSTEM ACROSS THE SOUTH. THE MAIN DILEMMA IS WHETHER TO SCATTER OUT THE CLOUD COVER THIS AFTN...AND TO LOWER CIGS/VSBYS ONCE AGAIN OVERNIGHT IN THE TYPICAL AREAS IN THE MN RIVER VALLEY TO AXN. ONE ITEM THAT DOES PLAY INTO THE FORECAST AFT 12Z TUE...IS THE INCREASING PRESSURE GRADIENT FROM THE STORM SYSTEM TO THE SOUTH. EVENTUALLY THE PRESSURE GRADIENT WILL PRODUCE A MORE EAST/NE FLOW TUE...AND ESPECIALLY TUE AFTN/EVENING. THIS WILL ALLOW FOR MORE MIXING AND THE BETTER CHC OF VFR CONDS TO DEVELOP AFT THIS TAF PERIOD. WILL CONTINUE PERSISTENCE WITH SOME VFR CONDS DEVELOPING THIS AFTN AT AXN/RWF/STC. THIS COULD BE VERY SHORT LIVED...OR EVEN NON-EXISTENT IF THE SUN ISOLATION IS NOT A FACTOR. KMSP... WILL CONTINUE THE MVFR CIGS THIS AFTN...WITH A POSSIBLE BREAK TO VFR BY 00Z. CONFIDENCE IS LOW AS MIXING IN THE BOUNDARY LAYER IS WEAK. EVENTUALLY WINDS WILL BECOME MORE E/NE LATE TONIGHT/TUESDAY WHICH SHOULD BEGIN TO ERODE THE STAGNANT AIR MASS THAT HAS BEEN IN PLACE OVER THE REGION. THE LATEST RAP/HOPWRF REMAINS VERY PESSIMISTIC FOR THE MVFR CIGS TO CONTINUE WITH VSBYS ALSO LOWERING OVERNIGHT. WILL CONTINUE THE SAME TREND WITH A PERIOD OF VFR THIS EVENING...THEN BECOMING MVFR ONCE AGAIN AFT 6Z...WITH THE POSSIBILITY OF VFR CONDS DEVELOPING AFT 18Z TUE. WINDS WILL BE LIGHT AND VARIABLE THRU 6Z...WITH A MORE E/NE FLOW DEVELOPING OVERNIGHT...AND BECOMING STRONGER FROM THE NE TUESDAY AFTN. /OUTLOOK FOR KMSP/ WED...MVFR IN THE MORNING...THEN VFR. WINDS NNW 15KTS. THU/FRI...VFR WITH MVFR CIGS POSSIBLE. WINDS N/NNE 5 TO 10KTS. ..JLT.. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ LS/JLT
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1126 AM CST MON FEB 25 2013 .DISCUSSION... OVERVIEW...SNOWSTORM STILL ON TRACK FOR THE CENTRAL/SOUTHERN PLAINS AND THE GREAT LAKES REGION OVER THE NEXT 48 HOURS. WE REMAIN ON THE NORTHERN FRINGE FOR EVEN LIGHT SNOW AT THIS POINT. BEST CHANCE FOR ANY SNOW REMAINS ACROSS PORTIONS OF WEST CENTRAL WISCONSIN AND SOUTHEAST MINNESOTA TUESDAY NIGHT AND WEDNESDAY. TEMPS WILL REMAIN NEAR CLIMATE NORMALS FOR THE NEXT SEVERAL DAYS. WEAK 850-700MB WARM ADVECTION AND EVEN A SMALL AMOUNT OF FGEN IN ROUGHLY THE SAME LAYER CONTRIBUTING TO THE LIGHT SNOW CURRENTLY STRETCHING FROM EASTERN NE TO SOUTHWEST MN. MOST OF THIS IS FALLING OUTSIDE OF THE FORECAST AREA...AND THERE IS EVEN LESS A CHANCE FOR LIGHT SNOW AFTER 12Z. INCLUDED SCATTERED FLURRIES IN WEST CENTRAL WI...BUT KEPT THE CHANCE FOR MEASURABLE UNDER 15%. TEMPS THIS MORNING ARE BEING HELD IN CHECK DUE TO THE STEADY STREAM OF MID AND HIGH CLOUDS FROM THE LOW CURRENTLY IN WESTERN TEXAS...AND LOW CLOUDS THAT WERE ADVECTED INTO MN SUNDAY AFTERNOON AND HAVE LINGERED SINCE. THE QUESTION IS IF AND OR WHEN DO WE CLEAR OUT TODAY. INCLUDED FOG IN THE GRID IN WESTERN/NORTHERN PORTIONS OF THE FORECAST AREA WHERE WE THINK THERE IS A BETTER CHANCE OF BEING CLEAR TONIGHT. DEVELOPING INVERSION TONIGHT ALONG HYDROLAPSE IN THE LOWEST 500 FT SUGGEST AREAS OF FOG ARE POSSIBLE. THERE ARE A COUPLE SITES THIS MORNING REPORTING DENSE FOG AND WITH A LITTLE MORE MELTING EXPECTED TODAY...FOG WILL REMAIN A PROBLEM IF WE CLEAR OUT TONIGHT. THE GRADIENT REMAINS LIGHT OVER THE NEXT 18-24 HOURS...HOWEVER...AS THE SURFACE LOW LIFTS INTO SOUTHERN MO LIGHT NORTHEAST WINDS ARE POSSIBLE BY 12Z TUESDAY ACROSS THE SOUTHERN HALF OF THE CWA. NOT SURE THIS WILL BE ENOUGH TO PROHIBIT FOG FORMATION. IT`S FAIRLY CLEAR AFTER VIEWING THE GFS/NAM/ECMWF OVER THE PAST FEW RUNS THAT THERE ISN`T MUCH CONCERN FOR SNOW IN THE FORECAST AREA TUESDAY NIGHT AND WEDNESDAY. THE TREND HAS BEEN NEAR STEADY TO A SLIGHT EASTWARD SHIFT WITH TIME. THE WEAK MID LEVEL FRONTOGENESIS THAT HANGS BACK WELL WEST OF THE SURFACE LOW ISN`T AS STRONG AS IT HAS LOOKED IN A COUPLE RUNS THIS PAST WEEKEND. THE MAIN 500 MB LIFTS OUT OF THE PLAINS OVER THE NEXT 24 HOURS...BUT ANY HOPE FOR LIGHT SNOW HERE SEEMS TO REST WITH THE SHORT WAVE NOW MOVING INLAND INTO WASHINGTON STATE AND BRITISH COLUMBIA. IN TERMS OF TEMPERATURES...REALLY STARTING TO SEE THE EFFECTS OF THE ALBEDO DIFFERENCES ACROSS THE FORECAST AREA...WITH THE SNOW COVERED PLAINS AND THE WOODED AREAS IN CENTRAL MN AND WI. EVEN THE METRO AREAS ARE SHOWING UP AS MORE PRONOUNCED WARM SPOTS WITH THE PROGRESSIVELY STRONGER LATE FEBRUARY SUNSHINE. THIS IS WHERE OUR BIAS CORRECTED DATABASE TYPICALLY STARTS DOMINATING THE VERIFICATION...BUT WE`LL HAVE TO WAIT FOR A MOSTLY SUNNY STRETCH TO SEE THE FULL BENEFIT OF BIAS CORRECTED GRIDS AND WE MIGHT BE FAIRLY CLOUDS THROUGH MID WEEK. HAVE TO ADMIT...NOT TERRIBLY CONFIDENT WITH THE CURRENT SKY AND TEMP FORECAST IN THE COMING DAYS. THERE IS SOME BUST POTENTIAL WITH THE HIGHS AND LOWS IN THE COMING DAYS...FOR SUNNY DAYS IN OUR LOW ALBEDO AREAS AND CLEAR NIGHTS WITH THE EXTENT OF OUR SNOW COVER. && .AVIATION.../18Z TAF ISSUANCE/ VERY COMPLICATED AVIATION FORECAST AS WINDS REMAIN NEARLY CALM UP TO 500 METERS WHICH WILL LIMIT ANY MIXING. THE ONLY HELP THIS AFTN IS THE HIGHER SUN ANGLE ALLOWING FOR BETTER ISOLATION WHICH WILL LEAD TO SOME EROSION IN THE CLOUDS FROM TOP TO BOTTOM. REGIONAL SATELLITE INDICATED THE BACK EDGE OF THE LOW CIGS ALONG THE ND/SD BORDER WITH LITTLE MOVEMENT EASTWARD OVER THE PAST FEW HRS. BASED ON THE LATEST RAP MIX LAYER UP TO 500 METERS...WINDS ARE NEARLY CALM AS EXPLAINED BEFORE WITH A MORE SW ORIENTATION NORTH/NE OF THE FA. A MORE N/NE FLOW ACROSS SW MN WHICH IS HAVING SOME AFFECTS FROM THE STORM SYSTEM ACROSS THE SOUTH. THE MAIN DILEMMA IS WHETHER TO SCATTER OUT THE CLOUD COVER THIS AFTN...AND TO LOWER CIGS/VSBYS ONCE AGAIN OVERNIGHT IN THE TYPICAL AREAS IN THE MN RIVER VALLEY TO AXN. ONE ITEM THAT DOES PLAY INTO THE FORECAST AFT 12Z TUE...IS THE INCREASING PRESSURE GRADIENT FROM THE STORM SYSTEM TO THE SOUTH. EVENTUALLY THE PRESSURE GRADIENT WILL PRODUCE A MORE EAST/NE FLOW TUE...AND ESPECIALLY TUE AFTN/EVENING. THIS WILL ALLOW FOR MORE MIXING AND THE BETTER CHC OF VFR CONDS TO DEVELOP AFT THIS TAF PERIOD. WILL CONTINUE PERSISTENCE WITH SOME VFR CONDS DEVELOPING THIS AFTN AT AXN/RWF/STC. THIS COULD BE VERY SHORT LIVED...OR EVEN NON-EXISTENT IF THE SUN ISOLATION IS NOT A FACTOR. KMSP... WILL CONTINUE THE MVFR CIGS THIS AFTN...WITH A POSSIBLE BREAK TO VFR BY 00Z. CONFIDENCE IS LOW AS MIXING IN THE BOUNDARY LAYER IS WEAK. EVENTUALLY WINDS WILL BECOME MORE E/NE LATE TONIGHT/TUESDAY WHICH SHOULD BEGIN TO ERODE THE STAGNANT AIR MASS THAT HAS BEEN IN PLACE OVER THE REGION. THE LATEST RAP/HOPWRF REMAINS VERY PESSIMISTIC FOR THE MVFR CIGS TO CONTINUE WITH VSBYS ALSO LOWERING OVERNIGHT. WILL CONTINUE THE SAME TREND WITH A PERIOD OF VFR THIS EVENING...THEN BECOMING MVFR ONCE AGAIN AFT 6Z...WITH THE POSSIBILITY OF VFR CONDS DEVELOPING AFT 18Z TUE. WINDS WILL BE LIGHT AND VARIABLE THRU 6Z...WITH A MORE E/NE FLOW DEVELOPING OVERNIGHT...AND BECOMING STRONGER FROM THE NE TUESDAY AFTN. /OUTLOOK FOR KMSP/ WED...MVFR IN THE MORNING...THEN VFR. WINDS NNW 15KTS. THU/FRI...VFR WITH MVFR CIGS POSSIBLE. WINDS N/NNE 5 TO 10KTS. ..JLT.. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ CF/JLT
AREA FORECAST DISCUSSION
NWS GLASGOW MT
858 PM MST TUE FEB 26 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY... MINOR TWEAKS TO SHORT TERM FORECAST FOR THIS UPDATE. CURRENTLY...A SMALL MID-LEVEL WAVE IS MOVING EASTWARD FROM MONTANA INTO NORTH DAKOTA. SOME VERY MILD DYNAMICAL LIFT WITH THIS WAVE HAS GENERATED SOME SHOWERS IN SOUTHEAST SASKATCHEWAN ALONG WITH A FEW SUB-TRACE SHOWERS IN NORTHEAST MONTANA. HRRR MODEL IS NOT OPTIMISTIC ABOUT ANYTHING MORE THAN A TRACE WITH THIS WAVE OVERNIGHT...SO HAVE LIGHT...BUT NOT NONEXISTENT...PPT IN THE FORECAST FOR THE NORTHEAST CORNER OF THE CWA OVERNIGHT. OUTSIDE OF THIS VERY LIMITED POSSIBILITY OF SHOWERS TONIGHT...SHORT TERM FORECAST THROUGH THURSDAY HAS LITTLE CHANCE FOR ANY PPT DUE TO WEAK AND ILL-DEFINED DYNAMICAL FEATURES. CLOUDS LOOK LIKE THEY WILL CLEAR FROM WEST TO EAST OVERNIGHT...SO SHADED TEMPERATURES LOWER IN THE WESTERN HALF OF THE CWA WHERE CLEARING SKIES SEEMS LIKELY TO ALLOW TEMPERATURES TO FALL IN THE EARLY MORNING HOURS. WEDNESDAY STILL LOOKS SLIGHTLY COOLER THAN TUESDAY...THOUGH LESS WINDY...WITH A WARMING TREND BEGINNING ON THURSDAY. MARTIN PREVIOUS DISCUSSION... A WEAK UPPER LEVEL TROUGH WILL DOMINATE THE WEATHER OF NORTHEAST MONTANA THROUGH THE SHORT TERM. GUSTY NORTHWEST WINDS WILL TAPER OFF THIS EVENING AS COLD AIR ADVECTION ENDS. SPLITTING ENERGY UNDER THE TROUGH WILL KEEP CONDITIONS MAINLY DRY ACROSS THE AREA TONIGHT. THE EXCEPTION TO THIS WILL BE THE NORTHEAST AND EAST WHICH COULD SEE SOME LIGHT SNOW SHOWERS AS THE NORTHERN BRANCH OF THE SPLITTING WAVE PUSHES THROUGH. WEDNESDAY THE WEATHER WILL BE QUIET IN BETWEEN SHORTWAVE FEATURES AND SKIES WILL AT LEAST PARTIALLY CLEAR. WEDNESDAY NIGHT A SECOND SHORTWAVE FEATURE WILL PUSH IN FROM THE WEST-NORTHWEST. MOISTURE IS LACKING WITH THIS FEATURE BUT IT COULD BRING SOME ISOLATED SHOWERS TO THE SOUTHWEST AS IT PUSHES IN. WEDNESDAY THE DISTURBANCE WILL EXIT THE REGION AS A NORTHWEST FLOW ALOFT BUILDS IN ON THE BACK SIDE OF THE UPPER TROUGH. AGAIN CONDITIONS WILL REMAIN MAINLY DRY...BUT AN ISOLATED SHOWER COULD POP UP AS THE ATMOSPHERE DESTABILIZES...THUS KEPT THE ISOLATED POPS IN THE SOUTHEAST. GILCHRIST .LONG TERM...THURSDAY NIGHT THROUGH TUESDAY... THE EXTENDED FORECAST REMAINS IN DECENT SHAPE. 12Z MODELS CONTINUE TO SHOW AN UPPER RIDGE BUILDING INTO NORTHEAST MONTANA DRIVING IN RISING 500MB HEIGHTS ALONG WITH WARMING 850MB TEMPERATURES BEGINNING ON THURSDAY NIGHT. THUS...CONTINUED THE TREND OF WARMING TEMPERATURES HEADING INTO SATURDAY. IN FACT...THE 12Z ECMWF HAS 850MB TEMPERATURES AS WARM AS +10C BY SATURDAY EVENING. IT IS NOT OUT OF THE REALM OF POSSIBILITY THAT SOME OF THE SOUTHWESTERN ZONES REACH HIGHS IN THE UPPER 50S. GIVEN THE RIDGE PARKED ACROSS THE AREA AND LARGE SCALE SUBSIDENCE...DECIDED TO ALSO KEEP THE CWA DRY. SUNDAY NIGHT AND BEYOND...THE POTENTIAL EXISTS FOR A SIGNIFICANT WINTER STORM TO AFFECT MONTANA LATE THIS WEEKEND INTO THE EARLY PORTIONS OF NEXT WEEK. THE 12Z ECMWF AND GFS HAVE COME INTO MUCH BETTER AGREEMENT ON TIMING SINCE PREVIOUS RUNS AND IT APPEARS NOW THAT THE BEST CHANCES OF PRECIPITATION WILL OCCUR FROM LATE SUNDAY EVENING LASTING PERHAPS AS LONG AS MONDAY NIGHT AS AN UPPER LEVEL SHORTWAVE TROUGH DIVES THROUGH THE NORTHWESTERN U.S. AND THEN INTO THE CENTRAL PLAINS. AN ASSOCIATED AREA OF SURFACE LOW PRESSURE WILL PASS SOUTH OF THE FORECAST AREA SUNDAY NIGHT AND SLIDE SOUTHEAST OF THE REGION MONDAY INTO MONDAY NIGHT. AS THIS HAPPENS...MOISTURE WILL WRAP AROUND THIS LOW PRESSURE SYSTEM AND INTO NORTHEAST MONTANA. THERMAL PROFILES ARE MARGINAL SUNDAY NIGHT AND SO THE ONSET PRECIPITATION MAY BEGIN IN THE FORM OF RAIN...BUT AS THE PRECIPITATION BECOMES STEADIER...DIABATIC COOLING WILL TAKE PLACE WHICH WILL ACT TO COOL THE VERTICAL PROFILES. COLD AIR WILL ALSO ADVECT INTO THE REGION BEHIND A COLD FRONTAL PASSAGE ASSOCIATED WITH THE SURFACE LOW. THIS WILL ALLOW ANY RAIN TO GRADUALLY TRANSITION TO ALL SNOW. AT THIS TIME IS WHEN THE BEST CHANCES FOR SNOWFALL ACCUMULATIONS WILL OCCUR ACROSS THE FORECAST REGION. HAVING SAID ALL THAT...FINAL SNOW AMOUNTS WILL GREATLY DEPEND UPON THE EXACT TRACK OF THE LOW PRESSURE SYSTEM AS WELL AS HOW MUCH OF THE PRECIPITATION FALLS AS RAIN. VERTICAL PROFILES DO SHOW PLENTY OF MOISTURE IN THE LOW AND MID LEVELS AND SO THE POTENTIAL EXISTS FOR SIGNIFICANT SNOWFALL ACCUMULATIONS TO OCCUR. HOWEVER...MANY OF THESE DETAILS DISCUSSED HERE ARE DIFFICULT TO DECIPHER THIS FAR OUT IN THE FORECAST PERIOD. GIVEN INCREASED SUPPORT FROM GUIDANCE ON THIS SYSTEM THOUGH...HAVE CERTAINLY INCREASED POPS ACROSS MUCH OF THE CWA SUNDAY INTO MONDAY NIGHT AND DROPPED TEMPERATURES. GUSTY WINDS ARE ALSO POSSIBLE ON THE BACKSIDE OF THIS LOW PRESSURE SYSTEM AS IT PULLS AWAY FROM THE FORECAST AREA. MALIAWCO PREVIOUS LONG TERM DISCUSSION... LENGTHENING DAYS AND A HIGHER SUN ARE BEGINNING TO SHOW AS THE WARMING CONTINUES. AN UPPER RIDGE BUILDING UP OVER THE WESTERN STATES WILL PUSH THE STATIONARY BOUNDARY EAST. THIS BOUNDARY WILL ACT AS A WARM FRONT THURSDAY NIGHT AND FRIDAY. EXPECT SOME ASSOCIATED CLOUDINESS WITH THE FRONT AND A LEE SIDE SURFACE TROUGH THROUGH FRIDAY NIGHT. 850MB TEMPERATURES WILL RAMP UP FROM AROUND -4C AT 00Z FRIDAY TO +4C AT 12Z SATURDAY. DURING THE SAME TIME FRAME 1000MB-500MB THICKNESS HEIGHTS INCREASE FROM 528DM TO 546DM. THEREFORE BEGINNING FRIDAY LOOK FOR ANOTHER SIGNIFICANT WARMING. GUIDANCE SUGGESTS TMAX ON SATURDAY REACHING THE UPPER 50S IN THE SW TO AROUND 40 IN THE NE AS THE RIDGE AXIS PEAKS OVER EASTERN MONTANA. WITH THE RAPIDLY DIMINISHING SNOW PACK THE HIGHS COULD TREND HIGHER. THESE MILD TEMPERATURE WILL LAST INTO SUNDAY. SUNDAY NIGHT AND BEYOND...A CLOSED PACIFIC LOW...CURRENTLY OUT NEAR THE WESTERN END OF THE ALEUTIANS ISLANDS...WILL BEGIN TO KNOCK DOWN THE RIDGE ON SUNDAY AS IT MOVES INTO THE NORTHERN ROCKIES. THIS STORM HAS MUCH MORE ENERGY THAN RECENT STORMS. THE UPPER LOW REMAINS CLOSED WHILE THE DEVELOPING LEE SURFACE TROUGH SHOWS SIGNS OF ALSO CLOSING OFF. THIS STORM SHOULD BRING MUCH MORE MOISTURE WITH IT...WHICH MIGHT FINALLY BRING IN SOME LOCAL PRECIPITATION. THE GFS IS QUICKER WITH THIS WAVE THAN THE EC...SO EXPECT THAT THE TIMING AND LOCATION HAVE NOT SETTLED IN YET...ALTHOUGH LATE IN THE SHIFT THE 00Z EC CAME IN MORE IN SYNC WITH THE 00Z GFS. THE TROUGH WILL SEND A DISTINCT COLD FRONT OVER THE REGION. WITH INITIALLY WARM TEMPERATURES...PRECIPITATION COULD BEGIN AS RAIN... THEN TURNING TO SNOW. BEYOND SUNDAY NIGHT LOCATION BECOME MUCH LESS CLEAR...BUT MODELS SUGGEST THE LOWS BEGIN TO STACK UP...WHICH COULD KEEP PRECIPITATION GOING WITH THE MOISTURE WRAPPING AROUND THE BACKSIDE OF THE STORM. THIS SYSTEM WILL LIKELY PRODUCE A SIGNIFICANT AMOUNT OF SNOW...BUT IT IS TOO EARLY TO TELL IF IT WILL BE IN SOUTHERN CANADA OR MONTANA. SCT && .AVIATION... MVFR CEILINGS THROUGH THIS EVENING. FUEL LOADING MAY BE NEEDED. CEILINGS WILL SHALLOW AND CLEAR DURING THE MID TO LATE MORNING WITH VFR BY THE AFTERNOON HOURS. WINDS WILL BE OUT OF THE NORTHWEST AROUND 5 TO 15 KTS OVERNIGHT SWITCHING TO THE EAST AND SOUTHEAST AROUND NOON. GAH && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
314 PM EST MON FEB 25 2013 .SYNOPSIS... LAKE EFFECT CLOUDS AND SCATTERED FLURRIES THIS MORNING...MAINLY IN CENTRAL NEW YORK...WILL YIELD TO BUILDING HIGH PRESSURE THIS AFTERNOON. THIS WILL HELP BREAK UP THE CLOUDS LATER TODAY...AND KEEP THINGS DRY AND QUIET TONIGHT THROUGH MOST OF TUESDAY. HOWEVER...A MIX OF WINTRY PRECIPITATION IS LIKELY LATE TUESDAY THROUGH EARLY WEDNESDAY AS LOW PRESSURE MOVES TOWARDS THE REGION FROM THE OHIO VALLEY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 1030 AM UPDATE... VSBL SAT ANIMATION INDICATES THAT CLDS ARE HANGING TOUGH LATE THIS MRNG ACRS CNY/PTNS OF NE PA. THE LATEST HI-RES NWP GUIDANCE STILL INDICATES THAT SOME DRYING WILL TAKE PLACE DURG THE COURSE OF THE AFTN...SPCLY FROM THE TWIN TIERS SWD. WE BLENDED IN THE LATEST RUC13 DATA...WHICH SEEMS TO HAVE A GOOD HANDLE ON THE CURRENT EVOLUTION. ANY LINGERING FLRYS SHOULD BE GONE BY 18-19Z. BASED ON THE 12Z RAOBS AND WEAK ANTICIPATED THERMAL ADVECTION THIS AFTN...OUR PRESENT HIGH TEMP FCST LOOKS GOOD...AND WAS ONLY TWEAKED VERY SLIGHTLY. PREV DISC... 630 AM UPDATE... GRIDS TWEAKED AS PER CURRENT OBS...AND TO LINGER CLOUD COVER A BIT LONGER INTO THE AFTERNOON. FORECAST GENERALLY ON TRACK...WITH ONLY SCATTERED FLURRIES REMAINING DOWNWIND OF LAKE ONTARIO. EARLIER DISCUSSION... ATMOSPHERIC COLUMN AS A WHOLE IS DRYING OUT...YET MOISTURE REMAINS TRAPPED IN THE LOWEST FEW THOUSAND FEET AGL UNDER A WEAK INVERSION. 850MB TEMPERATURES ARE ABOUT 9 OR 10 BELOW ZERO CELSIUS...BARELY ENOUGH FOR THE WEAK LAKE RESPONSE OF SCATTERED SNOW SHOWERS CURRENTLY DOWNWIND OF LAKE ONTARIO. WARM AIR ADVECTION ALOFT WILL GRADUALLY RAISE 850MB TEMPERATURES HEADING INTO THE DAY WHICH WILL ALLOW SNOW SHOWERS TO TAPER OFF TO A FEW FLURRIES BEFORE ENDING. HOWEVER...STRATOCUMULUS WILL BE A BIT MORE STUBBORN...ESPECIALLY CENTRAL NY. OVERALL...SUNSHINE WILL INCREASE THROUGH THE DAY BUT WILL TAKE LONGER IN SOME PLACES THAN OTHERS...AND HIGHS WILL BE RIGHT AROUND CLIMATOLOGICAL AVERAGES. HIGH PRESSURE IN CHARGE TONIGHT FOR QUIET AND MOSTLY CLEAR CONDITIONS. THE GOOD RADIATIONAL COOLING SET UP WILL YIELD MAINLY LOWER 20S FOR LOWS...THOUGH SOME TEENS FOR THE MORE TYPICALLY PRONE COLD AIR DRAINAGE VALLEYS. IN MANY CASES...AT OR SLIGHTLY BELOW COLDEST MODEL GUIDANCE. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... 500 AM UPDATE... TUESDAY....FAIRLY GOOD AGREEMENT AMONGST THE MODELS WITH REGARDS TO SYNOPTIC FEATURES WITH A DOMINANT SURFACE LOW AROUND 995 MB TRACKING THROUGH CENTRAL INDIANA WITH A NEW LOW FORMING OVER NORTH CENTRAL NC BY 0Z WEDNESDAY. THIS IS THE EASIEST PART OF THE FORECAST WITH THICKENING CLOUDS AND PRECIP HOLDING OFF UNTIL LATE IN THE DAY. LOOKING FOR ARRIVAL OF PRECIP TOWARD 23Z FAR SOUTH AND WEST. MODEL PROFILES SHOW WARM SURFACE TEMPS SO INITIAL SHOT OF PRECIP COULD BE IN THE FORM OF SNOW...SLEET OR PLAIN RAIN. TUESDAY NIGHT...UNCERTAINTY IS THE KEY WORD FOR THIS PART OF THE FORECAST. DESPITE GOOD MODEL AGREEMENT WITH THE SYNOPTIC PLAYERS...SUBTLE DIFFERENCES IN TEMP PROFILES GIVE US THE WHOLE RANGE OF P-TYPE POSSIBILITIES DURING THE NIGHT. IF THAT WERE NOT ENOUGH QPF AMOUNTS ARE ALSO HIGHER VARIABLE. WILL TACKLE EACH ISSUE SEPARATELY FOR NOW. P TYPE...THE EURO REMAINS THE COLDEST OF ALL MODELS SHOWING A MOSTLY SNOW EVENT FOR MOST OF THE CWA UNTIL CLOSER TO DAYBREAK WHEN WARMER AIR AROUND 850 MB MAKES ITS WAY INTO THE POCONOS. MEANWHILE THE GFS AND NAM ARE FAIRLY SIMILAR IN THAT THEY SHOW A TONGUE OF WARMER AIR AROUND 850 MB MOVE IN. THAT WOULD IMPLY ANY SNOW WOULD EVENTUALLY MIX WITH SLEET/FREEZING RAIN AND PLAIN RAIN. A FEW ITEMS THAT WE WILL BE WATCHING. THIS LAYER OF WARMER AIR ALOFT MAY BE ABLE TO BE OVERCOME FOR A PERIOD DURING THE NIGHT WHEN LIFT IS MAXIMIZED AND DYNAMIC COOLING ALLOWS FOR A SWITCH OVER TO ALL SNOW. WITH TEMP PROFILES SO CLOSE..THIS MAY BE JUST ENOUGH...ESPECIALLY OVER THE HIGHER TERRAIN OF THE CATSKILLS AND WESTERN SOUTHERN TIER FOR A PERIOD OF HEAVIER SNOW. HOWEVER...IF THE NAM AND GFS ARE CORRECT WITH THIS WARMER LAYER ALOFT...FREEZING RAIN POTENTIAL WILL HAVE TO BE WATCHED CAREFULLY. MOST MODEL SOUNDINGS SHOW SURFACE TEMPS NEAR OR BELOW FREEZING FROM ABOUT 04Z THROUGH 12Z...WITH MODEL QPFS AROUND A HALF OF AN INCH. CONFIDENCE HOWEVER IN THIS ICE POTENTIAL IS LOW GIVEN THE MODEL UNCERTAINTY WITH P-TYPE. IN ADDITION THOSE MODELS THAT SUGGEST THE WARMER LAYER ALOFT...ALSO SHOW A FAIRLY DEEP LAYER OF COLDER AIR BELOW THIS WARM NOSE WHICH WOULD SUGGEST PROLONGED SLEET VERSUS FREEZING RAIN. IF THE FREEZING RAIN DOES PAN OUT...THE POSITION OF THE SURFACE HIGH OVER NOVA SCOTIA WOULD GIVE US MORE OF AN EASTERLY COMPONENT TO THE SURFACE WIND WHICH MAY NOT LOCK IN THE COLD AIR AS MUCH FOR THE MAJORITY OF THE CWA...ASIDE FROM THE MOHAWK VALLEY WHERE IT IS IDEAL. WITH SO MUCH UNCERTAINTY PLAYED THE GRIDS TO SHOW THIS. PLAYED A WINTRY MIX FOR MOST OF THE AREA THROUGH THE NIGHT. BOTH THE EURO/NAM/AND GFS DO SHOW WARMER AIR MOVING INTO NEPA SO HERE I REMOVED THE MENTION OF SNOW OR SLEET IN THE WYOMING VALLEY TOWARD 12Z WITH ICE REMAINING IN THE POCONOS. WOULD LOVE TO BE MORE SPECIFIC BUT SOMETIMES WE JUST DON`T KNOW THIS FAR OUT YET AND DO NOT WANT TO CONVEY THAT WE KNOW THE EXACT P-TYPES THAT WILL FALL. QPF...THE NAM APPEARS TO BE WAY OVERDONE WITH QPF WITH VALUES OF BETWEEN .75" AND AN INCH BY 12Z WEDNESDAY. THE EURO IS ABOUT HALF THAT OR AROUND A HALF OF AN INCH...WITH THE SREFS AND GFS IN THE MIDDLE (.50-.75). PER COORDINATION WITH THE OTHER OFFICES DECIDED TO HOLD OFF ON ANY WATCHES WITH TOO MUCH UNCERTAINTY REGARDING P-TYPE. WEDNESDAY....SURFACE COLD AIR MAY REMAIN ACROSS THE MOHAWK VALLEY AND PARTS OF SULLIVAN COUNTY WITH THE EASTERLY FLOW...OTHERWISE WARM BOUNDARY LAYER TEMPS SUPPORT A CHANGE TO MOSTLY RAIN DURING THE DAY. TOWARD 0Z AS COLDER AIR MOVES IN FROM THE WEST SOME WET SNOW IS POSSIBLE. STILL SOME UNCERTAINTY HERE HOWEVER GIVEN THE EURO IS MUCH COLDER AND WOULD SUPPORT SNOW THROUGHOUT MOST OF THE DAY. WILL STICK WITH CONTINUITY FROM THE PREVIOUS FORECAST AS IT IS SUPPORTED BY THE GFS AND NAM...ALONG WITH MAIN SURFACE LOW TRACK BEING TO OUR WEST AND NOT A FAVORABLE POSITION OF THE SURFACE HIGH FOR ALL SNOW. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... XTNDD PD DOMINATED BY A MEANDERING UPR LVL LOW AND COOL AIR. LOW INITIALLY DRIFTS EAST EARLY IN THE PD...BUT IS REPLACED BY A SCNDRY LOW WHICH ROTATES BACK AROUND TROF INTO THE AREA. GFS IS A BIT MORE PROGRESSIVE THRU THE PD BUT WLD STILL KEEP THE AREA IN A NLY FLOW WITH DEEP MOISTURE. THERE/S NOT ANY STRONG LIFT WITH THE UPR LOW SO PCPN WILL BE LGT...BUT PERSISTENT. ALSO...TEMPS UNDER THE LOW SLOWLY MODIFY...WITH THE ECMWF BEING COOLER MAINTAINING THE UPR TROF. GNRLY FLWD THE HPC GUID THRU THE PD WHICH WAS CLOSER TO THE ECMWF...HWVR...DID ADJUST SLGTLY WRMR FOR COLLABORATION AND TO EDGE TWRD THE GFS. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... 18Z MON UPDATE... LWR CLDS (MVFR CIGS AT MOST SITES) WILL PERSIST THROUGH THIS EVE. LTR TNT (GENERALLY IN THE 03-09Z TIME FRAME)...SOME DRIER AIR AT LWR LVLS SHOULD BUILD IN...WITH CLEARING SKIES ANTICIPATED AT THAT TIME. VFR SHOULD THEN HOLD FOR THE REMAINDER OF THE VALID TAF PD (18Z TUE). THE NEXT ROUND OF WINTRY PCPN SHOULD HOLD OFF TIL LATE IN THE DAY TUE...OR EARLY IN THE EVE (22Z OR LATER). N TO NW WINDS 5-10 KT THIS AFTN...WILL TURN LGT AND VRBL TNT...BEFORE SHIFTING INTO THE SE TUE AM AT 5-10 KT. .OUTLOOK... TUE NGT/WED MRNG...MVFR TO IFR LIKELY...WITH A WINTRY MIX OF PCPN TYPES (SNOW/SLEET/FRZG RAIN). WED AFTN THRU FRI...RESTRICTIONS ARE LIKELY TO CONTINUE...WITH PDS OF LIGHT RAIN OR SNOW. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MDP NEAR TERM...MLJ/MDP SHORT TERM...HEDEN LONG TERM...DGM AVIATION...MLJ
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1206 PM EST MON FEB 25 2013 .SYNOPSIS... LAKE EFFECT CLOUDS AND SCATTERED FLURRIES THIS MORNING...MAINLY IN CENTRAL NEW YORK...WILL YIELD TO BUILDING HIGH PRESSURE THIS AFTERNOON. THIS WILL HELP BREAK UP THE CLOUDS LATER TODAY...AND KEEP THINGS DRY AND QUIET TONIGHT THROUGH MOST OF TUESDAY. HOWEVER...A MIX OF WINTRY PRECIPITATION IS LIKELY LATE TUESDAY THROUGH EARLY WEDNESDAY AS LOW PRESSURE MOVES TOWARDS THE REGION FROM THE OHIO VALLEY. && .NEAR TERM /THROUGH TONIGHT/... 1030 AM UPDATE... VSBL SAT ANIMATION INDICATES THAT CLDS ARE HANGING TOUGH LATE THIS MRNG ACRS CNY/PTNS OF NE PA. THE LATEST HI-RES NWP GUIDANCE STILL INDICATES THAT SOME DRYING WILL TAKE PLACE DURG THE COURSE OF THE AFTN...SPCLY FROM THE TWIN TIERS SWD. WE BLENDED IN THE LATEST RUC13 DATA...WHICH SEEMS TO HAVE A GOOD HANDLE ON THE CURRENT EVOLUTION. ANY LINGERING FLRYS SHOULD BE GONE BY 18-19Z. BASED ON THE 12Z RAOBS AND WEAK ANTICIPATED THERMAL ADVECTION THIS AFTN...OUR PRESENT HIGH TEMP FCST LOOKS GOOD...AND WAS ONLY TWEAKED VERY SLIGHTLY. PREV DISC... 630 AM UPDATE... GRIDS TWEAKED AS PER CURRENT OBS...AND TO LINGER CLOUD COVER A BIT LONGER INTO THE AFTERNOON. FORECAST GENERALLY ON TRACK...WITH ONLY SCATTERED FLURRIES REMAINING DOWNWIND OF LAKE ONTARIO. EARLIER DISCUSSION... ATMOSPHERIC COLUMN AS A WHOLE IS DRYING OUT...YET MOISTURE REMAINS TRAPPED IN THE LOWEST FEW THOUSAND FEET AGL UNDER A WEAK INVERSION. 850MB TEMPERATURES ARE ABOUT 9 OR 10 BELOW ZERO CELSIUS...BARELY ENOUGH FOR THE WEAK LAKE RESPONSE OF SCATTERED SNOW SHOWERS CURRENTLY DOWNWIND OF LAKE ONTARIO. WARM AIR ADVECTION ALOFT WILL GRADUALLY RAISE 850MB TEMPERATURES HEADING INTO THE DAY WHICH WILL ALLOW SNOW SHOWERS TO TAPER OFF TO A FEW FLURRIES BEFORE ENDING. HOWEVER...STRATOCUMULUS WILL BE A BIT MORE STUBBORN...ESPECIALLY CENTRAL NY. OVERALL...SUNSHINE WILL INCREASE THROUGH THE DAY BUT WILL TAKE LONGER IN SOME PLACES THAN OTHERS...AND HIGHS WILL BE RIGHT AROUND CLIMATOLOGICAL AVERAGES. HIGH PRESSURE IN CHARGE TONIGHT FOR QUIET AND MOSTLY CLEAR CONDITIONS. THE GOOD RADIATIONAL COOLING SET UP WILL YIELD MAINLY LOWER 20S FOR LOWS...THOUGH SOME TEENS FOR THE MORE TYPICALLY PRONE COLD AIR DRAINAGE VALLEYS. IN MANY CASES...AT OR SLIGHTLY BELOW COLDEST MODEL GUIDANCE. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... 500 AM UPDATE... TUESDAY....FAIRLY GOOD AGREEMENT AMONGST THE MODELS WITH REGARDS TO SYNOPTIC FEATURES WITH A DOMINANT SURFACE LOW AROUND 995 MB TRACKING THROUGH CENTRAL INDIANA WITH A NEW LOW FORMING OVER NORTH CENTRAL NC BY 0Z WEDNESDAY. THIS IS THE EASIEST PART OF THE FORECAST WITH THICKENING CLOUDS AND PRECIP HOLDING OFF UNTIL LATE IN THE DAY. LOOKING FOR ARRIVAL OF PRECIP TOWARD 23Z FAR SOUTH AND WEST. MODEL PROFILES SHOW WARM SURFACE TEMPS SO INITIAL SHOT OF PRECIP COULD BE IN THE FORM OF SNOW...SLEET OR PLAIN RAIN. TUESDAY NIGHT...UNCERTAINTY IS THE KEY WORD FOR THIS PART OF THE FORECAST. DESPITE GOOD MODEL AGREEMENT WITH THE SYNOPTIC PLAYERS...SUBTLE DIFFERENCES IN TEMP PROFILES GIVE US THE WHOLE RANGE OF P-TYPE POSSIBILITIES DURING THE NIGHT. IF THAT WERE NOT ENOUGH QPF AMOUNTS ARE ALSO HIGHER VARIABLE. WILL TACKLE EACH ISSUE SEPARATELY FOR NOW. P TYPE...THE EURO REMAINS THE COLDEST OF ALL MODELS SHOWING A MOSTLY SNOW EVENT FOR MOST OF THE CWA UNTIL CLOSER TO DAYBREAK WHEN WARMER AIR AROUND 850 MB MAKES ITS WAY INTO THE POCONOS. MEANWHILE THE GFS AND NAM ARE FAIRLY SIMILAR IN THAT THEY SHOW A TONGUE OF WARMER AIR AROUND 850 MB MOVE IN. THAT WOULD IMPLY ANY SNOW WOULD EVENTUALLY MIX WITH SLEET/FREEZING RAIN AND PLAIN RAIN. A FEW ITEMS THAT WE WILL BE WATCHING. THIS LAYER OF WARMER AIR ALOFT MAY BE ABLE TO BE OVERCOME FOR A PERIOD DURING THE NIGHT WHEN LIFT IS MAXIMIZED AND DYNAMIC COOLING ALLOWS FOR A SWITCH OVER TO ALL SNOW. WITH TEMP PROFILES SO CLOSE..THIS MAY BE JUST ENOUGH...ESPECIALLY OVER THE HIGHER TERRAIN OF THE CATSKILLS AND WESTERN SOUTHERN TIER FOR A PERIOD OF HEAVIER SNOW. HOWEVER...IF THE NAM AND GFS ARE CORRECT WITH THIS WARMER LAYER ALOFT...FREEZING RAIN POTENTIAL WILL HAVE TO BE WATCHED CAREFULLY. MOST MODEL SOUNDINGS SHOW SURFACE TEMPS NEAR OR BELOW FREEZING FROM ABOUT 04Z THROUGH 12Z...WITH MODEL QPFS AROUND A HALF OF AN INCH. CONFIDENCE HOWEVER IN THIS ICE POTENTIAL IS LOW GIVEN THE MODEL UNCERTAINTY WITH P-TYPE. IN ADDITION THOSE MODELS THAT SUGGEST THE WARMER LAYER ALOFT...ALSO SHOW A FAIRLY DEEP LAYER OF COLDER AIR BELOW THIS WARM NOSE WHICH WOULD SUGGEST PROLONGED SLEET VERSUS FREEZING RAIN. IF THE FREEZING RAIN DOES PAN OUT...THE POSITION OF THE SURFACE HIGH OVER NOVA SCOTIA WOULD GIVE US MORE OF AN EASTERLY COMPONENT TO THE SURFACE WIND WHICH MAY NOT LOCK IN THE COLD AIR AS MUCH FOR THE MAJORITY OF THE CWA...ASIDE FROM THE MOHAWK VALLEY WHERE IT IS IDEAL. WITH SO MUCH UNCERTAINTY PLAYED THE GRIDS TO SHOW THIS. PLAYED A WINTRY MIX FOR MOST OF THE AREA THROUGH THE NIGHT. BOTH THE EURO/NAM/AND GFS DO SHOW WARMER AIR MOVING INTO NEPA SO HERE I REMOVED THE MENTION OF SNOW OR SLEET IN THE WYOMING VALLEY TOWARD 12Z WITH ICE REMAINING IN THE POCONOS. WOULD LOVE TO BE MORE SPECIFIC BUT SOMETIMES WE JUST DON`T KNOW THIS FAR OUT YET AND DO NOT WANT TO CONVEY THAT WE KNOW THE EXACT P-TYPES THAT WILL FALL. QPF...THE NAM APPEARS TO BE WAY OVERDONE WITH QPF WITH VALUES OF BETWEEN .75" AND AN INCH BY 12Z WEDNESDAY. THE EURO IS ABOUT HALF THAT OR AROUND A HALF OF AN INCH...WITH THE SREFS AND GFS IN THE MIDDLE (.50-.75). PER COORDINATION WITH THE OTHER OFFICES DECIDED TO HOLD OFF ON ANY WATCHES WITH TOO MUCH UNCERTAINTY REGARDING P-TYPE. WEDNESDAY....SURFACE COLD AIR MAY REMAIN ACROSS THE MOHAWK VALLEY AND PARTS OF SULLIVAN COUNTY WITH THE EASTERLY FLOW...OTHERWISE WARM BOUNDARY LAYER TEMPS SUPPORT A CHANGE TO MOSTLY RAIN DURING THE DAY. TOWARD 0Z AS COLDER AIR MOVES IN FROM THE WEST SOME WET SNOW IS POSSIBLE. STILL SOME UNCERTAINTY HERE HOWEVER GIVEN THE EURO IS MUCH COLDER AND WOULD SUPPORT SNOW THROUGHOUT MOST OF THE DAY. WILL STICK WITH CONTINUITY FROM THE PREVIOUS FORECAST AS IT IS SUPPORTED BY THE GFS AND NAM...ALONG WITH MAIN SURFACE LOW TRACK BEING TO OUR WEST AND NOT A FAVORABLE POSITION OF THE SURFACE HIGH FOR ALL SNOW. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... 130 PM UPDATE... AS FRONT MVS THRU ON WEDNESDAY, CWA WL BE UNDER THE INFLUENCE OF H5 LOW CLOSING OFF ACRS NERN U.S. MED RANGE GUIDANCE CONTS TO SUGGEST THIS WL HAPPEN BY MID-WEEK AND EVENTUALLY HEAD EAST LATE IN THE WEEK (PER 00Z/12Z EURO) OR HANG OUT THRU THE WEEKEND (PER 12Z GFS). MAIN DIFFERENCES CNTR AROUND H5 HEIGHTS BEGINNING LATE IN THE WEEK WITH EURO DROPPING WAVE INTO THE INTERMOUNTAIN WEST WHILE GFS IS QUICKER WITH THIS WV AND MVS IT INTO THE DAKOTAS AT 12Z THURSDAY. BY 00Z FRIDAY, ECMWF APPEARS TO TREAT IT AS A KICKER AND KICKS THE UL TO THE EAST. GFS ALLOWS THIS WV TO GET ABSORBED AS IT DROPS INTO THE TN VLY AND JUST RE-INTENSIFIES THE LOW OVR TOP OF US. THE LATEST GFS IS QUITE A CHG FM ITS 06Z RUN AS IT APPEARED TO BE IN LOCK-STEP WITH ECMWF. THUS, HV FOLLOWED 12Z EURO DUE TO ITS CONSISTENCY WITH THE 00Z RUN. EITHER WAY, SCTD POPS EXPECTED FM THURSDAY ON IN ONE FORM OR ANOTHER, GENERALLY A RAIN/SNOW SHOWER MIX DRG THE DAYLIGHT HOURS AND SNOW SHOWERS AT NIGHT. GIVEN THE EXTENSIVE CLD CVR EXPECTED AND NW FLOW WORKING IN, TEMPS WL BE FAIRLY STEADY THRU THE PD WITH ONLY A DEGREE OR TWO CHANGE BTWN THE OVRNGT LOWS AND AFTN HIGHS. && .AVIATION /18Z MONDAY THROUGH FRIDAY/... 18Z MON UPDATE... LWR CLDS (MVFR CIGS AT MOST SITES) WILL PERSIST THROUGH THIS EVE. LTR TNT (GENERALLY IN THE 03-09Z TIME FRAME)...SOME DRIER AIR AT LWR LVLS SHOULD BUILD IN...WITH CLEARING SKIES ANTICIPATED AT THAT TIME. VFR SHOULD THEN HOLD FOR THE REMAINDER OF THE VALID TAF PD (18Z TUE). THE NEXT ROUND OF WINTRY PCPN SHOULD HOLD OFF TIL LATE IN THE DAY TUE...OR EARLY IN THE EVE (22Z OR LATER). N TO NW WINDS 5-10 KT THIS AFTN...WILL TURN LGT AND VRBL TNT...BEFORE SHIFTING INTO THE SE TUE AM AT 5-10 KT. .OUTLOOK... TUE NGT/WED MRNG...MVFR TO IFR LIKELY...WITH A WINTRY MIX OF PCPN TYPES (SNOW/SLEET/FRZG RAIN). WED AFTN THRU FRI...RESTRICTIONS ARE LIKELY TO CONTINUE...WITH PDS OF LIGHT RAIN OR SNOW. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MDP NEAR TERM...MLJ/MDP SHORT TERM...HEDEN LONG TERM...PVN AVIATION...MLJ
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1056 AM EST MON FEB 25 2013 .SYNOPSIS... LAKE EFFECT CLOUDS AND SCATTERED FLURRIES THIS MORNING...MAINLY IN CENTRAL NEW YORK...WILL YIELD TO BUILDING HIGH PRESSURE THIS AFTERNOON. THIS WILL HELP BREAK UP THE CLOUDS LATER TODAY...AND KEEP THINGS DRY AND QUIET TONIGHT THROUGH MOST OF TUESDAY. HOWEVER...A MIX OF WINTRY PRECIPITATION IS LIKELY LATE TUESDAY THROUGH EARLY WEDNESDAY AS LOW PRESSURE MOVES TOWARDS THE REGION FROM THE OHIO VALLEY. && .NEAR TERM /THROUGH TONIGHT/... 1030 AM UPDATE... VSBL SAT ANIMATION INDICATES THAT CLDS ARE HANGING TOUGH LATE THIS MRNG ACRS CNY/PTNS OF NE PA. THE LATEST HI-RES NWP GUIDANCE STILL INDICATES THAT SOME DRYING WILL TAKE PLACE DURG THE COURSE OF THE AFTN...SPCLY FROM THE TWIN TIERS SWD. WE BLENDED IN THE LATEST RUC13 DATA...WHICH SEEMS TO HAVE A GOOD HANDLE ON THE CURRENT EVOLUTION. ANY LINGERING FLRYS SHOULD BE GONE BY 18-19Z. BASED ON THE 12Z RAOBS AND WEAK ANTICIPATED THERMAL ADVECTION THIS AFTN...OUR PRESENT HIGH TEMP FCST LOOKS GOOD...AND WAS ONLY TWEAKED VERY SLIGHTLY. PREV DISC... 630 AM UPDATE... GRIDS TWEAKED AS PER CURRENT OBS...AND TO LINGER CLOUD COVER A BIT LONGER INTO THE AFTERNOON. FORECAST GENERALLY ON TRACK...WITH ONLY SCATTERED FLURRIES REMAINING DOWNWIND OF LAKE ONTARIO. EARLIER DISCUSSION... ATMOSPHERIC COLUMN AS A WHOLE IS DRYING OUT...YET MOISTURE REMAINS TRAPPED IN THE LOWEST FEW THOUSAND FEET AGL UNDER A WEAK INVERSION. 850MB TEMPERATURES ARE ABOUT 9 OR 10 BELOW ZERO CELSIUS...BARELY ENOUGH FOR THE WEAK LAKE RESPONSE OF SCATTERED SNOW SHOWERS CURRENTLY DOWNWIND OF LAKE ONTARIO. WARM AIR ADVECTION ALOFT WILL GRADUALLY RAISE 850MB TEMPERATURES HEADING INTO THE DAY WHICH WILL ALLOW SNOW SHOWERS TO TAPER OFF TO A FEW FLURRIES BEFORE ENDING. HOWEVER...STRATOCUMULUS WILL BE A BIT MORE STUBBORN...ESPECIALLY CENTRAL NY. OVERALL...SUNSHINE WILL INCREASE THROUGH THE DAY BUT WILL TAKE LONGER IN SOME PLACES THAN OTHERS...AND HIGHS WILL BE RIGHT AROUND CLIMATOLOGICAL AVERAGES. HIGH PRESSURE IN CHARGE TONIGHT FOR QUIET AND MOSTLY CLEAR CONDITIONS. THE GOOD RADIATIONAL COOLING SET UP WILL YIELD MAINLY LOWER 20S FOR LOWS...THOUGH SOME TEENS FOR THE MORE TYPICALLY PRONE COLD AIR DRAINAGE VALLEYS. IN MANY CASES...AT OR SLIGHTLY BELOW COLDEST MODEL GUIDANCE. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... 500 AM UPDATE... TUESDAY....FAIRLY GOOD AGREEMENT AMONGST THE MODELS WITH REGARDS TO SYNOPTIC FEATURES WITH A DOMINANT SURFACE LOW AROUND 995 MB TRACKING THROUGH CENTRAL INDIANA WITH A NEW LOW FORMING OVER NORTH CENTRAL NC BY 0Z WEDNESDAY. THIS IS THE EASIEST PART OF THE FORECAST WITH THICKENING CLOUDS AND PRECIP HOLDING OFF UNTIL LATE IN THE DAY. LOOKING FOR ARRIVAL OF PRECIP TOWARD 23Z FAR SOUTH AND WEST. MODEL PROFILES SHOW WARM SURFACE TEMPS SO INITIAL SHOT OF PRECIP COULD BE IN THE FORM OF SNOW...SLEET OR PLAIN RAIN. TUESDAY NIGHT...UNCERTAINTY IS THE KEY WORD FOR THIS PART OF THE FORECAST. DESPITE GOOD MODEL AGREEMENT WITH THE SYNOPTIC PLAYERS...SUBTLE DIFFERENCES IN TEMP PROFILES GIVE US THE WHOLE RANGE OF P-TYPE POSSIBILITIES DURING THE NIGHT. IF THAT WERE NOT ENOUGH QPF AMOUNTS ARE ALSO HIGHER VARIABLE. WILL TACKLE EACH ISSUE SEPARATELY FOR NOW. P TYPE...THE EURO REMAINS THE COLDEST OF ALL MODELS SHOWING A MOSTLY SNOW EVENT FOR MOST OF THE CWA UNTIL CLOSER TO DAYBREAK WHEN WARMER AIR AROUND 850 MB MAKES ITS WAY INTO THE POCONOS. MEANWHILE THE GFS AND NAM ARE FAIRLY SIMILAR IN THAT THEY SHOW A TONGUE OF WARMER AIR AROUND 850 MB MOVE IN. THAT WOULD IMPLY ANY SNOW WOULD EVENTUALLY MIX WITH SLEET/FREEZING RAIN AND PLAIN RAIN. A FEW ITEMS THAT WE WILL BE WATCHING. THIS LAYER OF WARMER AIR ALOFT MAY BE ABLE TO BE OVERCOME FOR A PERIOD DURING THE NIGHT WHEN LIFT IS MAXIMIZED AND DYNAMIC COOLING ALLOWS FOR A SWITCH OVER TO ALL SNOW. WITH TEMP PROFILES SO CLOSE..THIS MAY BE JUST ENOUGH...ESPECIALLY OVER THE HIGHER TERRAIN OF THE CATSKILLS AND WESTERN SOUTHERN TIER FOR A PERIOD OF HEAVIER SNOW. HOWEVER...IF THE NAM AND GFS ARE CORRECT WITH THIS WARMER LAYER ALOFT...FREEZING RAIN POTENTIAL WILL HAVE TO BE WATCHED CAREFULLY. MOST MODEL SOUNDINGS SHOW SURFACE TEMPS NEAR OR BELOW FREEZING FROM ABOUT 04Z THROUGH 12Z...WITH MODEL QPFS AROUND A HALF OF AN INCH. CONFIDENCE HOWEVER IN THIS ICE POTENTIAL IS LOW GIVEN THE MODEL UNCERTAINTY WITH P-TYPE. IN ADDITION THOSE MODELS THAT SUGGEST THE WARMER LAYER ALOFT...ALSO SHOW A FAIRLY DEEP LAYER OF COLDER AIR BELOW THIS WARM NOSE WHICH WOULD SUGGEST PROLONGED SLEET VERSUS FREEZING RAIN. IF THE FREEZING RAIN DOES PAN OUT...THE POSITION OF THE SURFACE HIGH OVER NOVA SCOTIA WOULD GIVE US MORE OF AN EASTERLY COMPONENT TO THE SURFACE WIND WHICH MAY NOT LOCK IN THE COLD AIR AS MUCH FOR THE MAJORITY OF THE CWA...ASIDE FROM THE MOHAWK VALLEY WHERE IT IS IDEAL. WITH SO MUCH UNCERTAINTY PLAYED THE GRIDS TO SHOW THIS. PLAYED A WINTRY MIX FOR MOST OF THE AREA THROUGH THE NIGHT. BOTH THE EURO/NAM/AND GFS DO SHOW WARMER AIR MOVING INTO NEPA SO HERE I REMOVED THE MENTION OF SNOW OR SLEET IN THE WYOMING VALLEY TOWARD 12Z WITH ICE REMAINING IN THE POCONOS. WOULD LOVE TO BE MORE SPECIFIC BUT SOMETIMES WE JUST DON`T KNOW THIS FAR OUT YET AND DO NOT WANT TO CONVEY THAT WE KNOW THE EXACT P-TYPES THAT WILL FALL. QPF...THE NAM APPEARS TO BE WAY OVERDONE WITH QPF WITH VALUES OF BETWEEN .75" AND AN INCH BY 12Z WEDNESDAY. THE EURO IS ABOUT HALF THAT OR AROUND A HALF OF AN INCH...WITH THE SREFS AND GFS IN THE MIDDLE (.50-.75). PER COORDINATION WITH THE OTHER OFFICES DECIDED TO HOLD OFF ON ANY WATCHES WITH TOO MUCH UNCERTAINTY REGARDING P-TYPE. WEDNESDAY....SURFACE COLD AIR MAY REMAIN ACROSS THE MOHAWK VALLEY AND PARTS OF SULLIVAN COUNTY WITH THE EASTERLY FLOW...OTHERWISE WARM BOUNDARY LAYER TEMPS SUPPORT A CHANGE TO MOSTLY RAIN DURING THE DAY. TOWARD 0Z AS COLDER AIR MOVES IN FROM THE WEST SOME WET SNOW IS POSSIBLE. STILL SOME UNCERTAINTY HERE HOWEVER GIVEN THE EURO IS MUCH COLDER AND WOULD SUPPORT SNOW THROUGHOUT MOST OF THE DAY. WILL STICK WITH CONTINUITY FROM THE PREVIOUS FORECAST AS IT IS SUPPORTED BY THE GFS AND NAM...ALONG WITH MAIN SURFACE LOW TRACK BEING TO OUR WEST AND NOT A FAVORABLE POSITION OF THE SURFACE HIGH FOR ALL SNOW. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... 130 PM UPDATE... AS FRONT MVS THRU ON WEDNESDAY, CWA WL BE UNDER THE INFLUENCE OF H5 LOW CLOSING OFF ACRS NERN U.S. MED RANGE GUIDANCE CONTS TO SUGGEST THIS WL HAPPEN BY MID-WEEK AND EVENTUALLY HEAD EAST LATE IN THE WEEK (PER 00Z/12Z EURO) OR HANG OUT THRU THE WEEKEND (PER 12Z GFS). MAIN DIFFERENCES CNTR AROUND H5 HEIGHTS BEGINNING LATE IN THE WEEK WITH EURO DROPPING WAVE INTO THE INTERMOUNTAIN WEST WHILE GFS IS QUICKER WITH THIS WV AND MVS IT INTO THE DAKOTAS AT 12Z THURSDAY. BY 00Z FRIDAY, ECMWF APPEARS TO TREAT IT AS A KICKER AND KICKS THE UL TO THE EAST. GFS ALLOWS THIS WV TO GET ABSORBED AS IT DROPS INTO THE TN VLY AND JUST RE-INTENSIFIES THE LOW OVR TOP OF US. THE LATEST GFS IS QUITE A CHG FM ITS 06Z RUN AS IT APPEARED TO BE IN LOCK-STEP WITH ECMWF. THUS, HV FOLLOWED 12Z EURO DUE TO ITS CONSISTENCY WITH THE 00Z RUN. EITHER WAY, SCTD POPS EXPECTED FM THURSDAY ON IN ONE FORM OR ANOTHER, GENERALLY A RAIN/SNOW SHOWER MIX DRG THE DAYLIGHT HOURS AND SNOW SHOWERS AT NIGHT. GIVEN THE EXTENSIVE CLD CVR EXPECTED AND NW FLOW WORKING IN, TEMPS WL BE FAIRLY STEADY THRU THE PD WITH ONLY A DEGREE OR TWO CHANGE BTWN THE OVRNGT LOWS AND AFTN HIGHS. && .AVIATION /16Z MONDAY THROUGH FRIDAY/... 12Z UPDATE... MOISTURE REMAINS TRAPPED UNDER INVERSION...WITH LIGHT NORTHWEST FLOW OFF OF LAKE ONTARIO ALLOWING AT LEAST MVFR CIGS TO PERSIST...AND EVEN STILL BRIEFLY IFR CIG KBGM AND KRME. GRADUAL IMPROVEMENT AND EVENTUAL SCATTERING OUT WILL OCCUR DURING THE AFTERNOON AS DRY AIR AND NEUTRALIZING INVERSION WIN OUT. CLEARING AND QUIET TONIGHT. THOUGH NOT IN TAFS DUE TO UNCERTAINTY...SOME MIST NOT OUT OF THE QUESTION FOR VALLEY TERMINALS DURING PREDAWN HOURS TUESDAY MORNING. .OUTLOOK... TUE...VFR...THEN MVFR ENCROACHING FROM SW LATE TUE AFTN. TUE NGT/WED MRNG...IFR/MVFR AND WINTRY MIX FROM LARGE SYSTEM. WED AFTN THRU FRI...IFR/MVFR IN INTERMITTENT SNOW AND RAIN SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MDP NEAR TERM...MLJ/MDP SHORT TERM...HEDEN LONG TERM...PVN AVIATION...MDP
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
731 PM EST TUE FEB 26 2013 .SYNOPSIS... A COLD FRONT WILL PUSH THROUGH THE AREA FROM THE WEST OVERNIGHT...AS LOW PRESSURE MOVES ACROSS TO THE WEST AND NORTH OF THE AREA. SLOW MOVING LOW PRESSURE OVER THE NORTHEAST WILL CIRCULATE A WESTERLY FLOW OF COLD AIR ACROSS THE REGION THURSDAY INTO THE WEEKEND. A SERIES OF LOW PRESSURE SYSTEMS WILL DEVELOP OFF THE SOUTHEAST AND MID ATLANTIC COASTS OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... WATCHING CLOSELY THE CONVECTION THAT HAS DEVELOPED IN THE VCNTY OF SFC TROF OVER THE PIEDMONT. NO LTG SEEN AS YET BUT THESE STORMS HAD KNOCKED SOME TREES DOWN AS THEY MOVE NEAR FLORENCE SC EARLIER THIS EVE BUT NO RECENT DAMAGE HAS BEEN REPORTED. VERY SHORT RANGE MODEL GUIDANCE VIA HRRR AND RAP SUGGESTS THE STORMS WEAKEN AS INSTABILITY REMAINS LACKING GOING INTO THE EVENING HOURS. VERY STRONG WINDS OF 40-50KT ARE BEING OBSERVED JUST ABOVE THE SURFACE AND ANY WEAK CONVECTION MAY BE ABLE TO BRING THESE DOWN AND CAUSE SOME MINOR DAMAGE THIS EVE. TEMPS WILL CONTINUE NON-DIURNAL TREND THIS EVENING...THEN WILL DROP OVERNIGHT WITH PASSAGE OF COLD FRONT. WENT WITH MOS BLEND...UPR 40S INLAND TO LOWER 50S COAST. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... AS OF 330 PM WEDNESDAY...MOSTLY SUNNY AND DRYING CONDITIONS EXPECTED WITH MODERATE SW WINDS...AS AREA WILL BE INFLUENCED BY BROAD CIRCULATION AROUND CONSOLIDATING LOW PRES OVER NEW ENGLAND. OFFSHORE WINDS WILL ALLOW TEMPS TO RISE BACK INTO LOW-MID 60S INLAND AS COLDER AIR MASS IS HELD OFF UNTIL WED NIGHT AND THU. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... AS OF 345 PM TUE...LOW PRES ACROSS THE GREAT LAKES WILL REMAIN NEARLY STATIONARY WED NIGHT THROUGH THU WHICH WILL RESULT IN TIGHTENED PRESSURE GRADIENT ACROSS EASTERN NC. FOR THUR...GUSTY WESTERLY WINDS IN WELL MIXED BOUNDARY LAYER WILL SUPPORT HIGHS WELL INTO THE 50S FOR THE AREA...AS DOWNSLOPING COMPONENT OFF SRN APPALACHIANS HELPS DRY THE LOWER ATMS. FRONT/SHORTWAVE WILL MIGRATE THROUGH THUR EVE. AT THIS TIME MOISTURE STILL APPEARS TO BE LIMITED...SO WILL CONTINUE TO LEAVE OUT PRECIP MENTION...JUST AN INCREASE IN CLOUD COVER AND COOLER AIRMASS. COOLER TEMPS EXPECTED FRI GENERALLY UPPER 40S TO LOWER 50S FOR HIGHS...AND LOWS IN THE 30S FRI MORNING. ANOMALOUS DEEP TROUGHING WILL BE IN PLACE THIS COMING WEEKEND AND TEMPS WILL BE QUITE A BIT COOLER THAN CLIMO. HAVE UNDERSHOT COOLEST ECMWF MOS GUIDANCE BY SEVERAL DEGREES DUE TO WARM BIAS TOWARDS CLIMO IN MOS OUTPUT. HIGH WILL GENERALLY BE IN THE 40S WITH LOWS NEAR FREEZING. HAVE CONTINUED TO MENTION SLIGHT CHANCE POPS SAT INTO SAT NIGHT AS DEEP UPPER LOW ROTATES THROUGH E NC...THOUGH ATTM MOISTURE PRESENCE IS QUESTIONABLE AS NO REAL SFC FEATURE IS PRESENT. GFS CONTINUES TO BE AN OUTLIER IN SPINNING UP SFC LOW NEAR THE COAST... OPER GFS LACKS SUPPORT FROM ITS 26/00Z ENSEMBLE MEAN...OPER ECM AND ECM ENSEMBLE MEAN SO HAVE CONTINUED TO KEEP NO HIGHER THAN 20 POPS IN GRIDS. IF PRECIP OCCURS...COULD CERTAINLY BE A RAIN/SNOW MIX INLAND AS BOUNDARY LAYER TEMPS COULD BE JUST COLD ENOUGH TO SUPPORT THE WINTRY MIX SAT NIGHT. AT THIS TIME BELIEVE TEMPS WILL BE JUST WARM ENOUGH TO KEEP PRECIP ALL RAIN ALONG THE COAST. UPPER TROUGH WILL MOVE OFF THE EAST COAST SUN NIGHT INTO MON. A SLIGHT WARMUP POSSIBLE BY TUE AS COLD UPPER LOW PULLS AWAY FROM THE REGION... THOUGH INDICATIONS ARE TO BE REPLACED BY REINFORCING COLD BY MID NEXT WEEK AS INDICIES INDICATE A CONTINUED BELOW NORMAL TEMP PATTERN. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... SHORT TERM /THROUGH 18Z WEDNESDAY/... CEILINGS HAVE LIFTED IN THE DEVELOPING DRY SLOT WORKING THRU EASTERN NC ATTM WITH CIGS NOW MVFR OR VFR AND IMPROVING. CONVECTION TO THE WEST SHUD BE WEAKENING BUT MAY SEE A BRIEF GUSTY SHOWER MOVE THRU THE TERMINALS 02-04Z. EXPECTED A PERIOD OF LOW CLOUDS/FOG TO BRIEFLY PRODUCE LIFR/IFR CONDITIONS DURING THE LATE EVENING AND VERY EARLY MORN BEFORE DEEPER DRYING MOVES IN WITH PASSAGE OF UPPER TROF IN THE 07-08Z TIME FRAME. VFR EXPECTED THEREAFTER THRU WED AS HIGH PRES BUILDS IN ALTHO WIND GUSTS 20-25 LIKELY FROM MID MORNING THRU MID AFTN COINCIDENT WITH BEST MIXING. LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... AS OF 345 PM TUE...MAINLY VFR THROUGH THE EXTENDED PERIOD. SOME INC IN CLOUDINESS WED NIGHT THOUGH SHOULD REMAIN VFR. GUSTY WESTERLY WINDS EXPECTED THUR LATE MORNING AND AFTERNOON. LIGHTER WINDS FOR THE FRI THROUGH WEEKEND TIME PERIOD... WITH WINDS IN THE NW TO N DIRECTION. && .MARINE... SHORT TERM /THROUGH TONIGHT/... AS OF 330 PM TUESDAY...STRONG SCA CONDITIONS CONTINUING TO SPREAD OVER AREA LATE THIS AFTN WITH WARM FRONT LIFTING N AS LOW PRES MOVES N OVER INLAND SECTIONS. LATEST GDNC SUPPORTS PREVIOUS FCST WITH STRONG SE TO S WINDS THIS EVENING...BECOMING SW AND SUBSIDING OVERNIGHT. GUSTY SW FLOW WILL CONTINUE OVER AREA WED...PRIMARILY OVER SRN AND CENTRAL WATERS. LATEST WW3 AND SWAN/NWPS SUPPORT PREVIOUS FCST WITH SEAS BUILDING TO 10-13 FT THIS EVENING...THEN GRADUALLY SUBSIDING OVERNIGHT AND WED. LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 345 PM TUE...UNSETTLED MARINE CONDITIONS EXPECTED TO CONTINUE INTO FRIDAY. LOW PRES WILL REMAIN NEARLY STATIONARY THROUGH THU. THIS WILL RESULT IN A CONTINUED TIGHTENED PRESSURE GRADIENT ACROSS THE WATERS WITH MODERATE TO STRONG WINDS AT TIMES. WSW WINDS 15-25KT WED NIGHT BECOME WLY THU. ELEVATED SEAS WILL CONTINUE THROUGH THU NIGHT/FRI. GRADIENT WILL BEGIN TO RELAX FRI NIGHT WITH WINDS AND SEAS SLOWLY SUBSIDING AS LOW MOVES OFF THE NE COAST. AN AREA OF LOW PRESSURE MAY DEVELOP OFF THE SE COAST SUN...THOUGH THERE IS STILL QUITE A BIT OF UNCERTAINTY WITH THIS FEATURE IN REGARDS TO POSITIONING...STRENGTH...OR IF THE SYSTEM DEVELOPS. SHOULD DEVELOPMENT OCCUR...WINDS WOULD BE STRONGER THAN CURRENTLY ADVERTISED FOR SUN INTO MON. && .TIDES/COASTAL FLOODING... NO CHANGE TO HIGH SURF ADVISORY FOR THIS EVENING. STRONG SOUTHEAST TO SOUTH FLOW WILL PRODUCE DANGEROUS ROUGH SURF ALONG THE COAST WITH 6 TO 8 FT BREAKERS EXPECTED. SOME MINOR WATER RISES OF 1-2 FT WILL OCCUR OVER PORTIONS OF MAINLAND HYDE...MAINLAND DARE...BEAUFORT...AND PAMLICO COUNTIES ADJACENT TO THE PAMLICO SOUND DUE TO THE STRONG SOUTHERLY FLOW BUT NO SIGNIFICANT ISSUES ARE EXPECTED. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...HIGH SURF ADVISORY UNTIL 1 AM EST WEDNESDAY FOR NCZ095-098-103- 104. MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EST WEDNESDAY FOR AMZ135. SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR AMZ130. SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR AMZ150-152-154- 156-158. && $$ SYNOPSIS...JBM NEAR TERM...JBM/BTC SHORT TERM...JBM LONG TERM...TL AVIATION...BTC/TL/LEP MARINE...JBM/TL TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
105 AM EST MON FEB 25 2013 .SYNOPSIS... HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST TONIGHT THEN MOVE OFF THE MID ATLANTIC COAST ON MONDAY. A WARM FRONT WILL APPROACH FROM THE SOUTH MONDAY NIGHT. LOW PRESSURE WILL DEVELOP ON THE WARM FRONT TUESDAY AND PASS TO THE WEST WITH ITS TRAILING COLD FRONT CROSSING TUESDAY NIGHT. A COLD TROUGH OF LOW PRESSURE WILL SETTLE OVER THE MID ATLANTIC STATES WEDNESDAY THROUGH THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 100 AM MONDAY...A WEAK EAST-WEST BOUNDARY NEAR THE PAMLICO RIVER AS SEEN AS A FINE LINE IN THE DOPPLER RADAR IMAGERY..IS MOVING RAPIDLY SOUTHWARD ACROSS EASTERN NC LATE TONIGHT. MAIN EFFECT IS FOR WINDS TO INCREASE OUT OF THE NORTH AND NORTHEAST BEHIND IT WHICH IS DISSIPATING THE PATCHES OF LOCALLY DENSE FOG WHICH HAVE FORMED ACROSS THE AREA LATE IN THE EVENING. EXPECT MOST IF NOT ALL OF THE FOG TO DIMINISHED BY 09Z. SKIES WILL BE CLEAR FOR THE REMAINDER OF THE NIGHT BEHIND THE BOUNDARY AS HIGH PRESSURE BUILDS INTO THE AREA FROM THE NORTH. TEMPERATURES STILL EXPECTED TO FALL INTO THE MIDDLE AND UPPER 30S RANGING TO THE MIDDLE 40S ALONG THE OUTER BANKS. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 AM TUESDAY/... LOW AMPLITUDE RIDGE CROSSES THE AREA MONDAY AS SFC HIGH MOVES OFFSHORE TO THE NE. SHUD SEE PLENTY OF SUN EARLY BUT INCREASING AFTERNOON CLOUDS AHEAD OF A SOUTHERN STREAM SYSTEM AND DEVELOPING ONSHORE BREEZE WILL HOLD HIGH TEMPS IN THE UPPER 40S TO LOWER 50S MOST AREAS. && .LONG TERM /TUESDAY THROUGH MONDAY/... AS OF 3 PM SUN...SFC HIGH PRES WILL BE RIDGING S INTO THE REGION WITH RIDGING ALOFT TO START THE LONG TERM BUT CONDITIONS WILL DETERIORATE MON NIGHT AS A ROBUST UPPER LEVEL CUT-OFF LOW CENTERED NEAR THE ARKLATEX REGION AT 00Z TUE LIFTS NE TO THE OHIO RIVER VALLEY THROUGH TUE NIGHT. CLOUDS WILL BE THICKENING AND LOWERING THROUGH THE EVENING BUT MODELS IN GOOD AGREEMENT WITH PCPN HOLDING OFF UNTIL AFTER MIDNIGHT...WITH STRONG ISENTROPIC LIFT SPREADING FROM SOUTH TO NORTH AFTER 09Z. PERIODS OF MODERATE TO HEAVY RAIN EXPECTED TUESDAY WITH A STRONG 50 KT LOW LEVEL JET TRANSPORTING ABUNDANT MOISTURE ACROSS THE AREA...PW`S INCREASE TO 1.5"...AND GOOD DIFLUENCE ALOFT AHEAD OF THE UPPER LOW. WIDESPREAD 1 TO 2" WILL BE POSSIBLE WITH LOCALLY HIGHER AMOUNTS WHICH MAY BRING MINOR FLOODING CONCERNS...ESPECIALLY ACROSS URBAN AND LOW LYING AREAS. THE WARM FRONT WILL LIFT N ACROSS THE AREA TUE AFTERNOON WHICH WILL BRIEFLY PLACE ERN NC IN THE WARM SECTOR OF THE SYSTEM WHICH MAY BRING JUST ENOUGH INSTABILITY...MAINLY ELEVATED...TO PRODUCE A FEW THUNDERSTORMS. WITH ABUNDANT SHEAR IN PLACE ANY THUNDERSTORMS THAT DEVELOP COULD HAVE THE POTENTIAL TO PRODUCE DAMAGING WIND GUSTS AND SPC HAS THE REGION IN A 5% PROBABILITY OF SEVERE. SHOWERS END TUE EVENING WITH LOW PRES LIFTING NORTH AND ASSOCIATED COLD FRONT MOVING ACROSS ERN NC. THE CUT-OFF LOW WILL REMAIN QUASI-STATIONARY ACROSS THE NRN MID-ATLANTIC STATES AND NEW ENGLAND THROUGH THE REST OF THE LONG TERM. A MID LEVEL VORT MAX MOVES ACROSS THE AREA WED WHICH MAY BRING AN ISOLATED SHOWER IF SUFFICIENT LOW LEVEL MOISTURE REMAINS...WHICH WILL MAINLY BE NORTH OF HIGHWAY 70. TEMPS WILL BE SEASONABLE WITH WRLY FLOW BRINGING HIGHS M50S TO AROUND 60 MOST AREAS. UPPER PATTERN WILL BECOME HIGHLY AMPLIFIED ACROSS THE EASTERN CONUS BY THE WEEKEND AS A ROBUST SHORTWAVE PIVOTS THROUGH THE FLOW ALOFT. A SERIES OF MAINLY DRY COLD FRONTAL PASSAGES WILL MOVE THROUGH GIVEN THE APPARENT LACK OF DEEP MOISTURE SOURCES IN THE OVERALL WESTERLY FLOW. TEMPS WILL SHOW A GRADUAL COOLDOWN THROUGH THE END OF THE WEEK AND WEEKEND WITH CAA BRINGING HEIGHT FALLS HIGHS IN THE MID 50S THU WILL COOL DOWN 2-3 DEGREES EACH DAY WITH HIGHS SUNDAY EXPECTED IN THE MID 40S WITH H85 TEMPS COOLING TO AROUND -8C. LOWS LIKELY AT OR BLO FREEZING INLAND THU NIGHT THROUGH SUN NIGHT. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... SHORT TERM /THROUGH MONDAY AFTERNOON/ AS OF 100 AM SUNDAY...PATCHES OF LOCALLY DENSE FOG WILL OCCUR AT THE SOUTHERN TAF SITES THROUGH 08Z THEN A WEAK BOUNDARY MOVING SOUTHWARD ACROSS THE AREA WILL CAUSE THE WINDS TO INCREASE OUT OF THE NORTH AND NORTHEAST AND DISSIPATE THE FOG. THEREAFTER EXPECTING VFR CONDITIONS FOR THE REMAINDER OF THE TAF PERIOD AS HIGH PRESSURE BUILDS IN WITH HIGH CLOUDS THICKENING AND LOWERING THIS AFTERNOON. LONG TERM /MON NIGHT THROUGH THURSDAY/... AS OF 3 PM SUN...VFR CONDITIONS TO START MON NIGHT BUT CONDITIONS DETERIORATE AFTER MIDNIGHT AS A ROBUST LOW PRES SYSTEM LIFT NW OF THE AREA. SUB-VFR CONDITIONS LIKELY LATE MON NIGHT INTO TUE EVENING...WITH IFR POSSIBLE TUE WITH HEAVIEST RAIN. ISOLATED TSTMS WILL BE POSSIBLE TUE AFTERNOON AND EVENING. COULD SEE S/SE WIND GUSTS AROUND 20-30 KT TUE AFTERNOON WITH STRONGER GUSTS IN TSTMS IF THEY DEVELOP. PRED VFR CONDITIONS WILL RETURN WED THROUGH FRI. && .MARINE... SHORT TERM /THROUGH TONIGHT/... AS OF 100 AM MONDAY...LATEST RAP MODEL INDICATES A SURGE WILL WORK ITS WAY DOWN THE COAST THROUGH THE OVERNIGHT HOURS. AS A RESULT...LIGHT SW/W WILL BECOME NORTH AND INCREASE TO 15 TO 20 KNOTS WITH A GUSTS TO 25 KTS AS HIGH PRESSURE OVER THE GREAT LAKES MOVES SOUTHEAST AND THE CAA SURGE WORKS DOWN THE COAST. WINDS GRADUALLY VEER NE AND DECREASE AS THE PRES GRADIENT EASES MON AFTERNOON. SEAS BUILD TO 5-7 FT LATE TONIGHT IN THE MODERATE NORTH FLOW THEN SLOWLY SUBSIDE MONDAY AFTN AS WINDS BEGIN TO VEER AND DECREASE. MAIN CHANGE TO THE FORECAST WAS TO EXTEND THE ADVISORY SOUTH DOWN TO CAPE LOOKOUT. LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... AS OF 3 PM SUN...UNSETTLED CONDITIONS EXPECTED THROUGH THE PERIOD. CONDITIONS WILL QUICKLY DETERIORATE MON NIGHT INTO EARLY TUE MORNING AS WARM FRONT AND AN AREA OF LOW PRESSURE LIFT INTO THE AREA...FLOWING BECOMING SE AND INCREASING TO 15-25KT TUE WITH SEAS BUILDING TO 7-12FT BY TUE EVENING. WINDS EXPECTED TO PEAK TUE AFTERNOON AND EVENING WITH A PERIOD OF GALE FORCE CONDITIONS POSSIBLE. A BRIEF PERIOD OF HIGH SURF CONDITIONS WILL ALSO BE POSSIBLE GIVEN STRONG ONSHORE FLOW AND BREAKING WAVES 7-10FT. TUE NIGHT THE SFC LOW WILL LIFT INTO THE MID-ATLANTIC WITH THE ATTENDANT COLD FRONT MOVING THROUGH THE WATERS. GRADIENT WILL REMAIN TIGHTENED THROUGH FRI WITH SW/W WINDS 15-25KT AND SEAS REMAINING AROUND 4-7 FT THROUGH THU...THEN SUBSIDE TO BLO 6 FT FRI. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR AMZ152- 154. SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR AMZ135- 150-156. && $$ SYNOPSIS...BTC NEAR TERM...CTC/JME SHORT TERM...BTC LONG TERM...SK AVIATION...JME/SK MARINE...CTC/BTC/JME/SK
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
848 PM CST TUE FEB 26 2013 .DISCUSSION... LATE AFTERNOON AND EARLY EVENING SAW LOW CLOUDS HANG ON IN A STRIP FROM CROOKSTON TO FARGO TO GWINNER AND FERGUS FALLS AND ELBOW LAKE. FOG QUICKLY RE-FORMED IN THIS AREA AND BY 02Z MANY SITES HAD DROPPED TO 1/4SM IN VSBY WITH FOG SPREADING TO HALLOCK AS WELL AND WEST INTO PARTS OF GRAND FORKS COUNTY. LATEST RAP MODEL AND OTHER SHORT RANGE MODELS INDICATE SFC-925 MB WINDS PICKING UP FROM THE NORTH LATE TONIGHT INTO WEDNESDAY SO THIS MAY HELP BREAK UP THE FOG A BIT EARLIER THAN OTHERWISE WOULD OCCUR. BUT AS USUAL WITH FOG THAT TIMING IS HIGHLY SUSPECT. ANOTHER PROBLEM TONIGHT IS THAT WIDESPREAD HIGH CLOUDS OVER THE AREA DUE TO THE LARGE STORM SYSTEM OVER THE CHICAGO AREA IS MASKING THE LOW CLOUDS BENEATH MAKING IT QUITE HARD TO SEE COVERAGE AND LOCATION OF LOW CLOUDS. TEMPS VARY AS WELL WITH FEW SITES DOWN TO 10F WHILE OTHER SITES NR 20. AVERAGE LOWS TONIGHT 10-15. && .AVIATION... TAF FORECASTS ARE VERY DIFFICULT TONIGHT INTO WEDNESDAY MORNING DUE TO THE PATCHY NATURE OF THE 1/4SM VSBY AND DUE TO HIGH CLOUDS MASKING THE LOW CLOUDS UNDERNEATH. GFK-FAR ESP VERY DIFFICULT AS 1/4SM VSBYS QUITE LIKELY BUT LENGTH OF TIME AT 1/4SM IS UNKNOWN AND VSBY COULD VARY GREATLY. OBS AT TVF IS NOT GETTING INTO THE COMMS SYSTEM THUS NO SKED AMENDMENTS FOR THAT SITE UNTIL COMMS PROBLEM RESOLVED. TICKET OPENED UP WITH FAA. BJI MAY SEE RADIATIONAL FOG LATER TONIGHT WHILE DVL REGION APPEARS LEAST PRONE TO FOG FORMATION AS IN PAST NIGHTS. .PREV DISCUSSION... /ISSUED 246 PM CST TUE FEB 26 2013/ SHORT TERM... FOG/STRATUS AND TEMPS REMAIN THE MAIN FORECAST CHALLENGES. HARD TO FIND A MODEL THAT HAS BEEN DEALING WELL WITH THE CURRENT CONDITIONS SO WILL HAVE TO RELY MORE ON TRENDS IN THE IMMEDIATE SHORT TERM. TONIGHT...THE WORST OF THE STRATUS AND FOG SEEM CONFINED TO THE IMMEDIATE RED RIVER VALLEY AND SOUTHEAST ND. IN THIS AREA TEMPS TODAY HAVE BEEN QUITE A BIT LOWER THAN SURROUNDING AREAS TO THE EAST AND WEST. LIKE THE PAST COUPLE OF DAYS THERE IS VERY LITTLE LOW LEVEL FLOW TO HELP SCOUR THIS OUT. THEREFORE WHERE THE STRATUS AND FOG ARE NOW MAY BE WHERE IT REMAINS FOR THE REST OF THE NIGHT. NOT AS SURE ABOUT DENSE FOG AGAIN SO WILL HAVE TO LET THE EVENING SHIFT MONITOR THAT ONCE AGAIN. AREAS WITH FOG AND LOW CLOUDS WILL STAY WARMER AS USUAL. WED-FRI...AMERICAN MODELS CONTINUE TO SHOW BETTER CHANCES FOR ANY LIGHT SNOW OR FLURRIES ON WED/THU THAN THE ECMWF. VERY WEAK FORCING SO WILL MATCH UP WITH NEIGHBORS AND GO WITH FLURRIES RATHER THAN LIGHT SNOW. TEMPS CONTINUE TO LOOK MILD ALTHOUGH THE RED RIVER VALLEY HAS TRENDED COOLER THAN PAST FEW DAYS. WILL NEED BETTER MIXING WITH WEST OR SW WINDS TO PUSH THE WARMER TEMPS DOWN INTO THE VALLEY AND REALLY DO NOT SEE THIS IN THE SHORT TERM. HARD TO FORECAST FOG TOO FAR OUT BUT IT SEEMS WE ARE GETTING BACK TO THE SPRING SNOWMELT SCENARIO WHERE MODELS FORECAST SUNNY DAYS BUT FOG/STRATUS HANG AROUND ALL DAY. LONG TERM (FRI NIGHT-TUE)... THROUGH THE WEEKEND MID LEVEL RIDGE OVER ROCKIES WILL SHIFT SLOWLY EAST. RIDGE AXIS REMAINS TO OUR WEST HOWEVER WEATHER TO BE QUIET WITH TEMPERATURES AT OR A LITTLE ABOVE AVERAGE. SURFACE LOW DROPPING INTO CENTRAL PLAINS EARLY NEXT WEEK WILL BRING FAVORED SNOW CHANCES TO WESTERN AND SOUTHERN PORTIONS OF THE REGION. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...DENSE FOG ADVISORY UNTIL 8 AM CST WEDNESDAY FOR NDZ008-016-027- 030-039-049-052-053. MN...DENSE FOG ADVISORY UNTIL 8 AM CST WEDNESDAY FOR MNZ001>004-007- 027-029-030-040. && $$ RIDDLE/GODON
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1255 PM EST MON FEB 25 2013 .SYNOPSIS... NORTH OF A DEVELOPING WARM FRONT...MOISTURE WILL SPREAD ATOP OUR REGION FROM THE GULF OF MEXICO. STRONG LOW PRESSURE WILL DRIVE A COLD FRONT ACROSS OUR AREA ON TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... 930 AM UPDATE...HIGH TEMPS HAVE BEEN LOWERED A FEW DEGREES. CAD WEDGE AND THICK CIRRUS DECK HAVE KEPT TEMPS COOLER THAN PREV FCST SO FAR TODAY. LATEST AVBL MOS GUIDANCE AS WELL AS RAW MODEL TEMPS KEPT PRACTICALLY ALL OF THE CWA IN THE 40S THROUGH THE DAY. FEEL THIS IS APPROPRIATE. AS FOR PRECIP...LATEST RAP INDICATES A WAVE OF PRECIP EARLY THIS AFTN THEN A LULL BEFORE WARM FRONTAL PRECIP TONIGHT. DISCOUNTING THIS AS MODEL CONSENSUS IS FOR STEADILY INCREASING LLVL ISENTROPIC FORCING FROM AFTN INTO EVENING...THUS OUR STEADILY INCREASING POPS LOOK GOOD. PREVIOUS DISCUSSION... A WELL DEFINED ULVL CONFLUENT ZONE HAS SET UP ACROSS THE NE CONUS WHICH IS ALLOWING A 1025 MB OH VALLEY SFC HIGH TO RIDGE EAST AND SOUTH INTO THE REGION. MEANWHILE...AN H5 S/W IS CROSSING TO THE SOUTH AND BRINGING IN A WIDE AREA OF CI. THIS SCENARIO IS CAPTURED WELL BY THE OP MODELS ALONG WITH A DEEPENING H5 CUTOFF LOW PROGGED TO MOVE INTO THE SRN MS RIVER VALLEY THROUGH THE PERIOD. A FAIRLY STRONG WEDGE WILL DEVELOP TODAY WHILE MOISTURE FLUX OFF BOTH THE GOM AND THE ATL ADVECT INTO THE AREA. CROSS SECTIONS ARE PRETTY CONSISTENT ON THE GFS/NAM/SREF WITH THE DEEPER MOISTURE AND ISENT OMEGA REACHING THE SRN ZONES AROUND 00Z AND SPREADING PRECIP OVER THE ENTIRE CWFA QUICKLY THROUGH 03Z. POPS WERE ADJ DOWN EARLY FOR A SOMEWHAT LATER ONSET TIME...BUT ALL AREAS SHOULD BE AT OR NEAR 100 POP BY 06Z THROUGH THE PERIOD. THERE IS NOT A LOT OF COOLING NOR LOW TD/S ASSOCIATED WITH THIS WEDGE...SO PRECIP TYPES OVERNIGHT WILL REMAIN RAIN AT ALL LOCALES...EXCEPT FOR THE HIGHER TERRAIN OF THE BLACK MTNS AND THE NRN MTNS WHERE PERIODS -FZRA WILL DEVELOP IN DIURNAL COOLING. MOST OF THESE LOCATIONS WONT SEE SIGFNT ICE ACCUMS...BUT ISOLATED PEAKS AROUND BEECH MTN COULD SEE A COUPLE TENTHS OF ICE AS THEY WILL EXPERIENCE THE LONGEST PERIOD OF ICING BEFORE LLVL WAA CHANGES ALL PRECIP TO RAIN. RAINFALL AMOUNTS OVERNIGHT WILL BE FAIRLY UNIFORM ACROSS THE NC ZONES...AROUND AN INCH...AND UP TO AN INCH AND A HALF ACROSS THE SRN ZONES AND NE GA. THIS WONT CREATE ANY FLOODING CONCERN DUE TO THE 12 HR TIMEFRAME...BUT ADDITIONAL RAINFALL THROUGH TUE MAY BEGIN TO ELEVATE SMALL STREAM AND CREEK LEVELS. ANOTHER ISSUE WITH THIS SYSTEM WILL BE THE HIGHLY DYNAMIC OCCLUDED SFC LOW TO THE WEST AND THE STRENGTHENING SFC RIDGE EAST. THIS WILL SET UP A RATHER STRONG P/GRAD...BUT THE SFC WINDS WONT BECOME OVERLY GUSTY WITH THE STRONGER VELOCITIES REMAINING ABOVE THE WEDGE INVERSION. THE HIGHER ELEVATIONS OF THE WRN NC MTNS WILL LIKELY SEE A SE/LY MTN WAVE SET UP AND DAMAGING WIND GUSTS FORCED TO THE SFC. THE MODELS ARE SHOWING VERY GOOD ISENT DECENT AND RELATIVELY DEEP NEG OMEGA AFT 06Z ALIGNED WITH WIND SPEEDS OF 55 KTS ABOVE 3.5 K FEET. BASED ON GOOD CONFIDENCE WITH THIS IMPENDING SCENARIO...A HIGH WIND WARNING WILL BE ISSUED FOR THE WRN NC MTNS ABOVE 3.5 K. MAX TEMPS TODAY WILL BE ON THE COOL SIDE WITH WEDGE AND CLOUD COVER. BLENDED THE OFFICIAL FCST WITH LOWER END METMOS GUIDANCE...WHICH GAVE MAXES IN THE L50S NON/MTNS...AND U40S MTN VALLEYS. CONTINUED NE/LY FLOW AND COOLER AIR ALOFT GUSTING TO THE SFC...YET HIGH CLOUD COVER...LOWS SHOULD DROP TO RIGHT AROUND NORMAL. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 330 AM EST MONDAY...THE SHORT RANGE WILL BE DOMINATED BY THE PASSAGE OF A LARGE AND DYNAMIC UPPER LOW MOVING FROM THE MID MS VALLEY...UP THE OH VALLEY...TO THE LOWER GREAT LAKES THROUGH THE PERIOD. THE MAIN ACTION WILL BE TUESDAY...WITH A CLASSIC COLD AIR DAMMING WEDGE IN PLACE AT SUNRISE WITH PRECIP FALLING ACROSS NEARLY THE ENTIRE FCST AREA. THERE ARE MANY CONCERNS. HIGH WIND POTENTIAL WILL REMAIN HIGH ALONG THE TN BORDER SO THE HIGH WIND WARNING WILL BE RUN THROUGH NOON. ANY LINGERING PRECIP TYPE ISSUES NEAR THE BLUE RIDGE OVER THE NRN MTNS AND NRN FOOTHILLS SHOULD GO AWAY QUICKLY AFTER SUNRISE WITH TEMPS WARMING ABOVE FREEZING. HEAVY RAIN IS ONE OF THE PRIMARY CONCERNS...AND THE OTHER IS SEVERE WEATHER. MUCH OF THIS WILL DEPEND ON THE TRACK OF A TRIPLE POINT LOW. THE LATEST MODEL GUIDANCE SHOWS THIS FEATURE MOVING ACROSS THE MIDDLE OF SC AND NC...OFF TO OUR EAST...DURING THE DAY. THIS WOULD TEND TO DECREASE THE HEAVY RAIN THREAT OVER THE MTNS AND BLUE RIDGE ALONG THE SC/NC BORDER. PW ANOMALIES ARE NOT OVERLY HIGH EITHER. WILL NOT ISSUE A FLOOD WATCH AT THIS TIME OWING TO THE DOWNWARD QPF TREND. AS FOR THE SEVERE WEATHER...IF THE TRIPLE POINT LOW TAKES A MORE WESTWARD TRACK AS SHOWN BY THE NAM...WE COULD GET THE SRN/ERN PARTS OF METRO CLT INTO THE WARMER AIR ON THE COASTAL SIDE OF THE WEDGE BOUNDARY IN THE LATE AFTERNOON...WHICH WOULD INCREASE THE THREAT FOR SEVERE STORMS. FOR NOW...WILL INCLUDE SOME THUNDER IN THE FCST THERE. THE PRECIP SHOULD EXIT THE REGION DURING THE LATE AFTERNOON AND EARLY EVENING ON TUESDAY...AFTER WHICH ANY LINGERING POP IS RELEGATED TO THE MTNS...MOSTLY NEAR THE TN BORDER. THE MAIN CULPRIT WILL BE WRAP-AROUND SHOWERS THROUGH TUESDAY NIGHT AND INTO WEDNESDAY. THE LOW LEVEL FLOW REMAINS SW INITIALLY AND IS ONLY SLOWLY EXPECTED TO COME AROUND TO W AND THEN NW WEDNESDAY NIGHT. THUS...PRECIP POTENTIAL WILL GRADUALLY IMPROVE WEDNESDAY NIGHT AS COLDER AIR MOVES IN TO CHANGE THE P-TYPE TO SNOW TOWARD DAYBREAK ON THURSDAY. SOME ACCUM SHOULD BE EXPECTED ON THE TN BORDER...AND THIS IS EXPECTED TO CONTINUE INTO THE MEDIUM RANGE. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 230 AM MONDAY...A DEEPENING LOW PRES SYSTEM WILL CONSOLIDATE OVER WRN PA/NY EARLY THU. THERE IS GOOD MODEL CONSENSUS ON THE LOCATION AND DEPTH OF THIS MAJOR FEATURE EARLY ON...BUT THEN VARYING SOLUTIONS ON ADDITIONAL ENERGY PIVOTING AROUND THE LOW AND CROSSING THE REGION FRI THROUGH SUN. AS THE LOW SLOWLY DEPARTS PA AND NY AREA TO THE EAST THURS THROUGH FRI...LOW LEVEL MOISTURE WILL BE IN PLACE OVER EAST TN UP AGAINST THE NC MTNS. THIS MOISTURE WILL BE DEEPEST IN THIS MEDIUM RANGE PERIOD ON THURS AND GRADUALLY DECREASE DEPENDING ON THE MODEL REFERENCED INTO THE WEEKEND. 850MB TEMPS OVER THE MTNS WILL RANGE FROM -5 TO -7C AT 12Z THURS BEING SLIGHTLY COLDEST IN THE ECMWF. THESE 850MB TEMPS WARM A DEGREE OR TWO INTO FRI AND THEN COLDER THROUGH THE WEEKEND DOWN TO -8 TO -11C 12Z SUNDAY. ALONG WITH THE DEEPEST MOISTURE ON THURSDAY...THE WIND IS FORECAST TO BE FROM THE WNW. AS THE LOW MOVES EAST ALONG WITH MORE SHALLOW MOISTURE...THE WIND BECOMES NW WHICH IS MOST FAVORABLE FOR UPSLOPE SNOW SHOWERS. SOME SHORTWAVE ENERGY ROUNDS THE BASE OF THE TROUGH LATE FRIDAY ENHANCING THE UPSLOPE SNSH. ANOTHER SPOKE OF ENERGY CROSSES SAT PM AND THE ECMWF CONTINUES TO HAVE A CUT OFF LOW WHICH KICKS OFF LIGHT PRECIP OVER ALL OF THE WESTERN CAROLINAS AND NORTH GA SAT PM. THE GFS HAS SOME PRECIP OVER NRN GA AND UPSTATE AND THE CMC LAYS OUT A BROADER TROUGH AND SMALLER AMOUNTS OF SPOTTY PRECIP. THE UPPER TROUGH AXIS IF FORECAST TO CROSS OUR AREA LATE SUNDAY. EXPECT MINS 5 TO 10 DEGREES BELOW NORMAL...WITH MAXES 10 TO 15 DEGREES BELOW NORMAL...THROUGH THE PERIOD. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AT KCLT...CIRRUS CIG THIS AFTN WILL BEGIN TO LOWER BY LATE AFTN AS ISENTROPIC LIFT OVER COLD SFC WEDGE RAMPS UP. LOW VFR LOOKS TO SET IN BY ABOUT 01Z FOLLOWED BY RAPID LOWERING TO IFR CIG WITH ONSET OF RAINFALL THAT WILL CONTINUE THROUGH THE END OF THE PERIOD. GUIDANCE SUGGESTS MVFR VSBY WILL ACCOMPANY THE RAIN BUT FOG NOT EXPECTED WITH NEAR SFC AIR REMAINING DRY. WINDS REMAIN NE TO ENE UNDER THE WEDGE GRADUALLY INCREASING IN STRENGTH AS SFC LOW ENTERS OHIO VALLEY. APPROACHING COLD FRONT WILL LIKELY SCOUR OUT THE WEDGE...TURN WINDS SWLY AND END THE PRECIP...BUT CURRENT TIMING HAS THIS OCCURRING AFTER 18Z. ELSEWHERE...VFR CIGS THIS AFTN WILL LOWER FROM SOUTH TO NORTH AS WARM FRONT/ISENTROPIC LIFT INCREASES AHEAD OF APPROACHING SFC LOW. FAR SOUTHERN PART OF THE FCST AREA EXPECTED TO SEE MVFR CIG BY AROUND SUNSET WHEN PRECIP SHOULD ALSO BEGIN. PRECIP WILL SPREAD NORTHWARD ACROSS ALL SITES OVERNIGHT PEAKING IN COVERAGE AROUND SUNRISE. RAIN WILL LIKELY LOWER VSBY TO MVFR...AND THOUGH SFC TEMPS MAY REMAIN JUST ABOVE FREEZING IN THE MTNS SOME SNOW/SLEET MAY MIX WITH THE RAIN THERE LATE TONIGHT. GUIDANCE GIVING FAIRLY STRONG SIGNAL OF WIDESPREAD IFR CIGS ACROSS THE AREA FORMING AROUND 09Z. THIS IS LIKELY TO LAST UNTIL COLD FRONT WORKS INTO THE REGION FROM THE WEST NEAR THE END OF THE PERIOD. KAVL MAY SEE LIFTING TO VFR JUST BEFORE 18Z. WINDS WILL REMAIN IN NE QUADRANT AT ALL SITES UNTIL THE FRONT MOVES THROUGH...AGAIN THE ONLY SITE AFFECTED IS KAVL. OUTLOOK...CLEARING SKIES ARE IN STORE TUESDAY NIGHT WITH VFR EXPECTED THROUGH THURSDAY EAST OF THE MOUNTAINS. SOME POTENTIAL FOR MVFR ACROSS THE NC MTNS WITH SNOW SHOWERS MID TO LATE WEEK. CONFIDENCE TABLE... 18-24Z 00-06Z 06-12Z 12-18Z KCLT HIGH 100% HIGH 100% MED 72% HIGH 93% KGSP HIGH 100% HIGH 81% MED 62% HIGH 89% KAVL HIGH 100% HIGH 87% HIGH 83% HIGH 80% KHKY HIGH 100% HIGH 100% MED 75% HIGH 89% KGMU HIGH 100% MED 79% MED 62% HIGH 89% KAND HIGH 100% MED 75% MED 77% HIGH 93% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...HIGH WIND WARNING FROM MIDNIGHT TONIGHT TO 6 PM EST TUESDAY FOR NCZ033-048>052-058-059. WIND ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST TUESDAY FOR NCZ033-048>052-058-059. SC...NONE. && $$ SYNOPSIS...DEO NEAR TERM...SBK/WIMBERLEY SHORT TERM...PM LONG TERM...DEO AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
944 AM EST MON FEB 25 2013 .SYNOPSIS... HIGH PRESSURE CENTERED OVER THE GREAT LAKES TODAY AS MOISTURE SPREADS OVER OUR REGION FROM THE GULF OF MEXICO AHEAD OF A WARM FRONT. STRONG LOW PRESSURE WILL MOVE FROM NORTHEAST TEXAS TODAY TO WESTERN KENTUCKY LATE TUESDAY. A COLD FRONT WILL CROSS OUR AREA WEDNESDAY EVENING. && .NEAR TERM /THROUGH TONIGHT/... 930 AM UPDATE...HIGH TEMPS HAVE BEEN LOWERED A FEW DEGREES. CAD WEDGE AND THICK CIRRUS DECK HAVE KEPT TEMPS COOLER THAN PREV FCST SO FAR TODAY. LATEST AVBL MOS GUIDANCE AS WELL AS RAW MODEL TEMPS KEPT PRACTICALLY ALL OF THE CWA IN THE 40S THROUGH THE DAY. FEEL THIS IS APPROPRIATE. AS FOR PRECIP...LATEST RAP INDICATES A WAVE OF PRECIP EARLY THIS AFTN THEN A LULL BEFORE WARM FRONTAL PRECIP TONIGHT. DISCOUNTING THIS AS MODEL CONSENSUS IS FOR STEADILY INCREASING LLVL ISENTROPIC FORCING FROM AFTN INTO EVENING...THUS OUR STEADILY INCREASING POPS LOOK GOOD. PREVIOUS DISCUSSION... A WELL DEFINED ULVL CONFLUENT ZONE HAS SET UP ACROSS THE NE CONUS WHICH IS ALLOWING A 1025 MB OH VALLEY SFC HIGH TO RIDGE EAST AND SOUTH INTO THE REGION. MEANWHILE...AN H5 S/W IS CROSSING TO THE SOUTH AND BRINGING IN A WIDE AREA OF CI. THIS SCENARIO IS CAPTURED WELL BY THE OP MODELS ALONG WITH A DEEPENING H5 CUTOFF LOW PROGGED TO MOVE INTO THE SRN MS RIVER VALLEY THROUGH THE PERIOD. A FAIRLY STRONG WEDGE WILL DEVELOP TODAY WHILE MOISTURE FLUX OFF BOTH THE GOM AND THE ATL ADVECT INTO THE AREA. CROSS SECTIONS ARE PRETTY CONSISTENT ON THE GFS/NAM/SREF WITH THE DEEPER MOISTURE AND ISENT OMEGA REACHING THE SRN ZONES AROUND 00Z AND SPREADING PRECIP OVER THE ENTIRE CWFA QUICKLY THROUGH 03Z. POPS WERE ADJ DOWN EARLY FOR A SOMEWHAT LATER ONSET TIME...BUT ALL AREAS SHOULD BE AT OR NEAR 100 POP BY 06Z THROUGH THE PERIOD. THERE IS NOT A LOT OF COOLING NOR LOW TD/S ASSOCIATED WITH THIS WEDGE...SO PRECIP TYPES OVERNIGHT WILL REMAIN RAIN AT ALL LOCALES...EXCEPT FOR THE HIGHER TERRAIN OF THE BLACK MTNS AND THE NRN MTNS WHERE PERIODS -FZRA WILL DEVELOP IN DIURNAL COOLING. MOST OF THESE LOCATIONS WONT SEE SIGFNT ICE ACCUMS...BUT ISOLATED PEAKS AROUND BEECH MTN COULD SEE A COUPLE TENTHS OF ICE AS THEY WILL EXPERIENCE THE LONGEST PERIOD OF ICING BEFORE LLVL WAA CHANGES ALL PRECIP TO RAIN. RAINFALL AMOUNTS OVERNIGHT WILL BE FAIRLY UNIFORM ACROSS THE NC ZONES...AROUND AN INCH...AND UP TO AN INCH AND A HALF ACROSS THE SRN ZONES AND NE GA. THIS WONT CREATE ANY FLOODING CONCERN DUE TO THE 12 HR TIMEFRAME...BUT ADDITIONAL RAINFALL THROUGH TUE MAY BEGIN TO ELEVATE SMALL STREAM AND CREEK LEVELS. ANOTHER ISSUE WITH THIS SYSTEM WILL BE THE HIGHLY DYNAMIC OCCLUDED SFC LOW TO THE WEST AND THE STRENGTHENING SFC RIDGE EAST. THIS WILL SET UP A RATHER STRONG P/GRAD...BUT THE SFC WINDS WONT BECOME OVERLY GUSTY WITH THE STRONGER VELOCITIES REMAINING ABOVE THE WEDGE INVERSION. THE HIGHER ELEVATIONS OF THE WRN NC MTNS WILL LIKELY SEE A SE/LY MTN WAVE SET UP AND DAMAGING WIND GUSTS FORCED TO THE SFC. THE MODELS ARE SHOWING VERY GOOD ISENT DECENT AND RELATIVELY DEEP NEG OMEGA AFT 06Z ALIGNED WITH WIND SPEEDS OF 55 KTS ABOVE 3.5 K FEET. BASED ON GOOD CONFIDENCE WITH THIS IMPENDING SCENARIO...A HIGH WIND WARNING WILL BE ISSUED FOR THE WRN NC MTNS ABOVE 3.5 K. MAX TEMPS TODAY WILL BE ON THE COOL SIDE WITH WEDGE AND CLOUD COVER. BLENDED THE OFFICIAL FCST WITH LOWER END METMOS GUIDANCE...WHICH GAVE MAXES IN THE L50S NON/MTNS...AND U40S MTN VALLEYS. CONTINUED NE/LY FLOW AND COOLER AIR ALOFT GUSTING TO THE SFC...YET HIGH CLOUD COVER...LOWS SHOULD DROP TO RIGHT AROUND NORMAL. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 330 AM EST MONDAY...THE SHORT RANGE WILL BE DOMINATED BY THE PASSAGE OF A LARGE AND DYNAMIC UPPER LOW MOVING FROM THE MID MS VALLEY...UP THE OH VALLEY...TO THE LOWER GREAT LAKES THROUGH THE PERIOD. THE MAIN ACTION WILL BE TUESDAY...WITH A CLASSIC COLD AIR DAMMING WEDGE IN PLACE AT SUNRISE WITH PRECIP FALLING ACROSS NEARLY THE ENTIRE FCST AREA. THERE ARE MANY CONCERNS. HIGH WIND POTENTIAL WILL REMAIN HIGH ALONG THE TN BORDER SO THE HIGH WIND WARNING WILL BE RUN THROUGH NOON. ANY LINGERING PRECIP TYPE ISSUES NEAR THE BLUE RIDGE OVER THE NRN MTNS AND NRN FOOTHILLS SHOULD GO AWAY QUICKLY AFTER SUNRISE WITH TEMPS WARMING ABOVE FREEZING. HEAVY RAIN IS ONE OF THE PRIMARY CONCERNS...AND THE OTHER IS SEVERE WEATHER. MUCH OF THIS WILL DEPEND ON THE TRACK OF A TRIPLE POINT LOW. THE LATEST MODEL GUIDANCE SHOWS THIS FEATURE MOVING ACROSS THE MIDDLE OF SC AND NC...OFF TO OUR EAST...DURING THE DAY. THIS WOULD TEND TO DECREASE THE HEAVY RAIN THREAT OVER THE MTNS AND BLUE RIDGE ALONG THE SC/NC BORDER. PW ANOMALIES ARE NOT OVERLY HIGH EITHER. WILL NOT ISSUE A FLOOD WATCH AT THIS TIME OWING TO THE DOWNWARD QPF TREND. AS FOR THE SEVERE WEATHER...IF THE TRIPLE POINT LOW TAKES A MORE WESTWARD TRACK AS SHOWN BY THE NAM...WE COULD GET THE SRN/ERN PARTS OF METRO CLT INTO THE WARMER AIR ON THE COASTAL SIDE OF THE WEDGE BOUNDARY IN THE LATE AFTERNOON...WHICH WOULD INCREASE THE THREAT FOR SEVERE STORMS. FOR NOW...WILL INCLUDE SOME THUNDER IN THE FCST THERE. THE PRECIP SHOULD EXIT THE REGION DURING THE LATE AFTERNOON AND EARLY EVENING ON TUESDAY...AFTER WHICH ANY LINGERING POP IS RELEGATED TO THE MTNS...MOSTLY NEAR THE TN BORDER. THE MAIN CULPRIT WILL BE WRAP-AROUND SHOWERS THROUGH TUESDAY NIGHT AND INTO WEDNESDAY. THE LOW LEVEL FLOW REMAINS SW INITIALLY AND IS ONLY SLOWLY EXPECTED TO COME AROUND TO W AND THEN NW WEDNESDAY NIGHT. THUS...PRECIP POTENTIAL WILL GRADUALLY IMPROVE WEDNESDAY NIGHT AS COLDER AIR MOVES IN TO CHANGE THE P-TYPE TO SNOW TOWARD DAYBREAK ON THURSDAY. SOME ACCUM SHOULD BE EXPECTED ON THE TN BORDER...AND THIS IS EXPECTED TO CONTINUE INTO THE MEDIUM RANGE. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 230 AM MONDAY...A DEEPENING LOW PRES SYSTEM WILL CONSOLIDATE OVER WRN PA/NY EARLY THU. THERE IS GOOD MODEL CONSENSUS ON THE LOCATION AND DEPTH OF THIS MAJOR FEATURE EARLY ON...BUT THEN VARYING SOLUTIONS ON ADDITIONAL ENERGY PIVOTING AROUND THE LOW AND CROSSING THE REGION FRI THROUGH SUN. AS THE LOW SLOWLY DEPARTS PA AND NY AREA TO THE EAST THURS THROUGH FRI...LOW LEVEL MOISTURE WILL BE IN PLACE OVER EAST TN UP AGAINST THE NC MTNS. THIS MOISTURE WILL BE DEEPEST IN THIS MEDIUM RANGE PERIOD ON THURS AND GRADUALLY DECREASE DEPENDING ON THE MODEL REFERENCED INTO THE WEEKEND. 850MB TEMPS OVER THE MTNS WILL RANGE FROM -5 TO -7C AT 12Z THURS BEING SLIGHTLY COLDEST IN THE ECMWF. THESE 850MB TEMPS WARM A DEGREE OR TWO INTO FRI AND THEN COLDER THROUGH THE WEEKEND DOWN TO -8 TO -11C 12Z SUNDAY. ALONG WITH THE DEEPEST MOISTURE ON THURSDAY...THE WIND IS FORECAST TO BE FROM THE WNW. AS THE LOW MOVES EAST ALONG WITH MORE SHALLOW MOISTURE...THE WIND BECOMES NW WHICH IS MOST FAVORABLE FOR UPSLOPE SNOW SHOWERS. SOME SHORTWAVE ENERGY ROUNDS THE BASE OF THE TROUGH LATE FRIDAY ENHANCING THE UPSLOPE SNSH. ANOTHER SPOKE OF ENERGY CROSSES SAT PM AND THE ECMWF CONTINUES TO HAVE A CUT OFF LOW WHICH KICKS OFF LIGHT PRECIP OVER ALL OF THE WESTERN CAROLINAS AND NORTH GA SAT PM. THE GFS HAS SOME PRECIP OVER NRN GA AND UPSTATE AND THE CMC LAYS OUT A BROADER TROUGH AND SMALLER AMOUNTS OF SPOTTY PRECIP. THE UPPER TROUGH AXIS IF FORECAST TO CROSS OUR AREA LATE SUNDAY. EXPECT MINS 5 TO 10 DEGREES BELOW NORMAL...WITH MAXES 10 TO 15 DEGREES BELOW NORMAL...THROUGH THE PERIOD. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... AT KCLT /15Z UPDATE/...LATEST PROG SOUNDINGS SHOW SOME MIXING OCCURRING IN COLD WEDGE DESPITE MUCH SFC WARMING. SOME LOW END GUSTS HAVE ALREADY OCCURRED AND MORE COULD OCCUR...BUT WINDS SHOULD GRADUALLY INCREASE TO A STEADY 10KT OR SO REDUCING GUST FREQUENCY. UPPER LEVEL CLOUDS WILL LOWER THROUGH THE PERIOD ALONG WITH PERHAPS A FEW LOW VFR CLOUDS SEEN THIS AFTN. MVFR CIGS EXPECTED AFTER 03Z. A CONTINUED LOWERING DECK TO IFR BY 10Z WILL BE ACCOMPANIED BY -SHRA. THE WEDGE WILL STRENGTHEN AS THE PRECIP MOVES IN AND NE/LY WINDS WILL VEER TO ENE/LY AROUND 00Z AND BECOME MODERATELY GUSTY THROUGH THE REMAINDER OF THE TAF PERIOD. ELSEWHERE...WITH A SFC WEDGE STRENGTHENING DURING THE DAY...WINDS WILL BE MAINTAINED GENERALLY NE/LY AT ALL NON/MTN TAF SITES BECOMING GUSTY AROUND 00Z. WINDS WILL HAVE LESS GUST POTENTIAL...BUT STILL SUSTAINED AROUND 10 KTS...AT KAVL AND ALIGNED SE/LY DOWN THE FRENCH BROAD VALLEY. ALL SITES WILL EXPERIENCE LOWERING CIGS INTO MVFR ACCOMPANIED BY -SHRA BY 00Z WITH IFR PROBABLE ACROSS THE UPSTATE AROUND 09Z. OUTLOOK...CLEARING SKIES ARE IN STORE TUESDAY NIGHT WITH VFR EXPECTED THROUGH THURSDAY EAST OF THE MOUNTAINS. SOME POTENTIAL FOR MVFR ACROSS THE NC MTNS WITH SNOW SHOWERS MID TO LATE WEEK. CONFIDENCE TABLE... 14-20Z 20-02Z 02-08Z 08-14Z KCLT HIGH 100% HIGH 100% HIGH 94% HIGH 94% KGSP HIGH 100% HIGH 100% HIGH 86% HIGH 92% KAVL HIGH 100% HIGH 100% HIGH 84% HIGH 92% KHKY HIGH 100% HIGH 100% HIGH 95% HIGH 92% KGMU HIGH 100% HIGH 100% HIGH 87% HIGH 92% KAND HIGH 100% HIGH 83% HIGH 91% HIGH 85% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...HIGH WIND WARNING FROM MIDNIGHT TONIGHT TO 6 PM EST TUESDAY FOR NCZ033-048>052-058-059. WIND ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST TUESDAY FOR NCZ033-048>052-058-059. SC...NONE. && $$ SYNOPSIS...DEO NEAR TERM...SBK/WIMBERLEY SHORT TERM...PM LONG TERM...DEO AVIATION...SBK/WIMBERLEY
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
350 PM CST MON FEB 25 2013 .DISCUSSION... POWERFUL WINTER STORM CONTINUES TO MOVE THROUGH THE SOUTHERN PLAINS THIS AFTERNOON RESULTING IN PRIMARILY A WIND EVENT ACROSS NORTH TEXAS...BUT SOME WINTRY WEATHER IS EXPECTED THROUGH THIS EVENING FOR PARTS OF THE AREA. LATEST SURFACE ANALYSIS SHOWS THE CENTER OF THE SURFACE LOW NEAR EL DORADO ARKANSAS WHERE 3 HOUR PRESSURE FALLS ARE IN EXCESS OF 7MB. PRESSURE FALLS EXTEND ALL THE WAY WESTWARD TOWARD WICHITA FALLS WHERE A SURFACE TROUGH HAS PERSISTED ALL DAY. THESE PERSISTENT PRESSURE FALLS ARE AN INDICATION THAT THE ENTIRE UPPER STORM SYSTEM IS DEEPENING. WATER VAPOR IMAGERY SHOWS A WELL DEFINED CIRCULATION WHICH APPEARS TO NOW BE MOVING DUE EAST TOWARD THE BEST SURFACE PRESSURE FALLS. THIS IS CONCERNING BECAUSE SUBSTANTIAL WRAP AROUND PRECIPITATION DRIVEN BY FRONTOGENETICAL FORCING WILL LIKELY TRACK FARTHER SOUTH THAN EARLIER ANTICIPATED. SHORT TERM HIGH RESOLUTION GUIDANCE APPEARS TO HAVE SOMEWHAT OF A HANDLE ON THE MOVEMENT OF THE UPPER SYSTEM BUT PRECIPITATION IS QUICKLY ERODED DUE TO STRONG SUBSIDENCE. MESOSCALE FRONTOGENETICAL FORCING IS LIKELY TO WIN OUT AT LEAST FOR A FEW HOURS ON THE BACK SIDE OF THE SYSTEM RESULTING IN PRECIPITATION ACROSS MAINLY THE NORTHWEST COUNTIES THROUGH MIDNIGHT. CONCERNING THE PRECIPITATION...FORECAST SOUNDINGS FROM BOTH THE HIGH RES 3KM TTU WRF AND RAP MODEL SUGGEST THAT THE THERMAL PROFILE WILL BE SUFFICIENTLY COLD FOR SNOWFALL PRODUCTION GENERALLY NORTH OF INTERSTATE 20 THROUGH LATE TONIGHT...DESPITE THE WARM SURFACE TEMPERATURES. INITIAL CONVECTIVE SHOWERS NORTHEAST OF THE METROPLEX SHOULD REMAIN ALL LIQUID. GIVEN THE POTENTIAL FOR SNOWFALL...ALONG WITH STRONG GUSTY WINDS...HAVE ISSUED A SHORT DURATION WINTER WEATHER ADVISORY FOR THE FAR NORTHWEST COUNTIES THROUGH MIDNIGHT. WITH WARM GROUND TEMPERATURES AND GENERALLY ABOVE FREEZING SURFACE TEMPERATURES...EXPECT ANY ACCUMULATIONS TO BE CONFINED TO GRASSY SURFACES. THE PRIMARY CONCERN WILL BE FOR BLOWING SNOW WHICH COULD REDUCE VISIBILITY TO LESS THAN 1/2 MILE AT TIMES. ROADS SHOULD REMAIN IN GOOD SHAPE. THE OTHER MAIN CONCERN IS WINDS THROUGH LATE TONIGHT. WITH THE CENTER OF THE SURFACE LOW NEARBY FOR MUCH OF THE AFTERNOON...WINDS HAVE GENERALLY BEEN HIGHEST ACROSS THE SOUTHERN COUNTIES WHERE GUSTS TO 54 MPH HAVE BEEN REPORTED. WITH THE SURFACE LOW NOW MOVING EAST...THE PRESSURE GRADIENT WILL CONTINUE TO TIGHTEN THROUGH EVENING. THE STRONGEST LOW LEVEL JET WILL BE CENTERED ACROSS THE AREA RIGHT AROUND MIDNIGHT SO IT APPEARS THAT THE STRONGEST WINDS ACROSS MUCH OF THE REGION ARE STILL TO COME. ONE LIMITING FACTOR TO STRONGER WINDS WILL BE THE FACT THAT IT WILL BE NIGHT WHEN THE STRONGEST WINDS ALOFT ARE OVERHEAD. THE CURRENT WIND ADVISORY WILL REMAIN IN EFFECT THROUGH 4 AM FOR ALL OF NORTH TEXAS. WITH THE ENTIRE SYSTEM MOVING TO THE NORTHEAST TOMORROW...SKIES SHOULD CLEAR AND WINDS WILL DIMINISH. A COUPLE OF REINFORCING FRONTS...ONE ON WEDNESDAY AND ANOTHER LATE THURSDAY NIGHT...WILL KEEP TEMPERATURES COOL THROUGH THE WEEK. NO SIGNIFICANT CHANGES TO THE EXTENDED FORECAST AS IT APPEARS THAT IT WILL REMAIN DRY THROUGH THE PERIOD. DUNN && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 35 54 34 54 34 / 20 5 0 0 5 WACO, TX 35 61 34 60 33 / 5 0 0 0 5 PARIS, TX 36 49 31 51 31 / 40 5 0 0 5 DENTON, TX 35 53 30 51 31 / 30 5 0 0 5 MCKINNEY, TX 36 52 32 51 32 / 30 5 0 0 5 DALLAS, TX 37 56 35 55 35 / 20 5 0 0 5 TERRELL, TX 36 52 34 54 34 / 10 5 0 0 5 CORSICANA, TX 37 57 35 58 34 / 5 0 0 0 5 TEMPLE, TX 36 63 36 63 33 / 5 0 0 0 5 MINERAL WELLS, TX 34 57 30 54 29 / 40 0 0 0 5 && .FWD WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 4 AM CST TUESDAY FOR TXZ091>095-100>107- 115>123-129>135-141>148-156>162-174-175. WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR TXZ091- 100-101-115. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS AMARILLO TX
1157 AM CST MON FEB 25 2013 .AVIATION... FOR THE 18Z TAFS...AN AVIATION WEATHER WARNING REMAINS IN EFFECT FOR KAMA AND TRADEWIND AIRPORT THROUGH 00Z TONIGHT DUE TO STRONG GUSTY WINDS. SNOW...BLOWING SNOW...AND GUSTY WINDS WILL BE THE PRIMARY FOCUS THROUGH EARLY EVENING. SNOW HAS STOPPED AT KDHT...WITH THE POSSIBILITY FOR BLOWING SNOW THROUGH 21Z AS WINDS REMAIN GUSTY TO 45KTS. CEILINGS SHOULD CONTINUE TO IMPROVE THROUGH 03Z WHEN SKIES WILL CLEAR AT KAMA AND KGUY...SNOW AND BLOWING SNOW CONTINUE TO REDUCE VISIBILITY BELOW 1 MILE...WITH KAMA VSBY AT 1/4SM TO 1/2SM WHILE SNOW REMAINS HEAVY. SNOW SHOULD TAPER OFF BY 00Z. IFR CEILINGS SLOWLY IMPROVING TO MVFR CEILINGS BY 21Z TO 00Z...BEFORE CLEARING AFTER 03Z. NF && .PREV DISCUSSION... /ISSUED 1057 AM CST MON FEB 25 2013/ UPDATE... MADE MINOR ADJUSTMENTS TO THE SNOW AMOUNT GRIDS FROM NOON TO 6 PM TO ACCOUNT FOR HIGHER SNOWFALL RATES AS THE UPPER LOW LIFTS TO THE NORTH AND EAST. DURING THIS TIME FRAME 3 TO 6 ADDITIONAL INCHES OF SNOW WILL BE POSSIBLE ACROSS THE EASTERN OKLAHOMA AND TEXAS PANHANDLE AND THE SOUTH CENTRAL TEXAS PANHANDLE. PREV DISCUSSION... /ISSUED 833 AM CST MON FEB 25 2013/ .CRIPPLING BLIZZARD ROARS ON... UPDATE... GOING FORECAST STILL ON TRACK. THE NWS OFFICE NOW HAS OVER 13 INCHES ON THE GROUND WITH 3-4 FOOT DRIFTS AND A MAX GUST TO 58 MPH. THE SE TX PANHANDLE HAS BEEN SLOW TO FILL IN WITH SNOW AFTER THE THUNDERSTORMS THAT DROPPED HEAVY RAIN LAST NIGHT AND THESE AREAS MIGHT END UP WITH AMOUNTS CLOSER TO THE 8 INCH SIDE THAN THE 14 INCH SIDE OF THEIR RANGE. AT THE END OF THE DAY...THE HEAVIEST TOTALS WILL ALMOST CERTAINLY BE ALONG A PALO DURO CANYON TO AMARILLO TO STINNETT TO PERRYTON LINE. SOME RECORDS SEEM TO BE IN A PRECARIOUS POSITION TODAY. THE FIRST IS AN ALL-TIME 24 HOUR SNOWFALL RECORD AT AMARILLO OF 20.6 INCHES FROM MARCH 25-26 1934. WE WILL LIKELY GET VERY CLOSE OR SURPASS THIS NUMBER BY THIS AFTERNOON. THE OTHER IS THE ALL-TIME STATE OF TEXAS 24 HOUR SNOWFALL RECORD OF 25 INCHES IN FOLLETT SET MARCH 28 2009. SOMEWHERE IN THE PERRYTON/STINNETT/BORGER/AMARILLO AREA COULD APPROACH THIS VALUE BY THIS AFTERNOON. SIMPSON PREV DISCUSSION... /ISSUED 541 AM CST MON FEB 25 2013/ AVIATION.../12Z TAFS/ VERY HAZARDOUS FLYING CONDITIONS EXPECTED TO CONTINUE THROUGH AT LEAST 00Z AT ALL TERMINALS. HEAVIEST SNOW AND LOWEST VISIBILITIES WILL BE AT KAMA 15-20Z. AWW REMAINS IN EFFECT FOR KAMA AND TRADEWINDS AIRPORT UNTIL 00Z. VFR CONDITIONS ARE EXPECTED TO RETURN TO ALL TERMINALS 00-02Z. NW WINDS ARE EXPECTED TO SUBSIDE BELOW 12 KT AT ALL TERMINALS BY 04Z. JACKSON PREV DISCUSSION... /ISSUED 446 AM CST MON FEB 25 2013/ SNOW PILING UP...WINDS INCREASING AND CREATING FULL FLEDGED BLIZZARD CONDITIONS AT THIS WRITING... DISCUSSION... MAIN CHANGE TO PREVIOUS FORECAST WAS TO ATTEMPT TO PIN POINT THE BAND OF HIGHEST SNOW TOTALS...WHICH WILL LIKELY STRETCH ALONG AN ARC FROM TULIA TO AMARILLO TO STINNETT TO SPEARMAN. LOCATIONS ON THIS ARC AND 30 MILES TO THE EAST AND WEST OF IT ARE SET TO RECEIVE AT LEAST A FOOT OF SNOW...WITH TOTALS UP TO 2 FEET NOT COMPLETELY OUT OF THE QUESTION. THE REST OF THE PANHANDLES WILL SEE SLIGHTLY LESSER AMOUNTS...BUT STILL BLIZZARD CONDITIONS. SEE THE BLIZZARD WARNING AND GRAPHICS ON WFO AMA HOMEPAGE AND FACEBOOK FOR A BETTER REPRESENTATION OF THIS EVENT THAN CAN BE TYPED IN BLOCK TEXT. THE NAM AND RUC HAVE DONE A GOOD JOB IN SHOWING A STRONG BAND OF FRONTOGENETICAL FORCING...THOUGH THE PLACEMENT HAS BEEN TOO FAR EAST. THIS BAND HAS SET UP OVER THE AFOREMENTIONED ARC AND CONVECTIVE ENHANCEMENT WITH RATES TO 2-3 INCHES PER HOUR HAVE BEEN NOTED. IN FACT...WE HAVE OBSERVED AT LEAST A HALF DOZEN CLOUD TO GROUND STRIKES AT THE NWS AMA OFFICE OVERNIGHT...WITH ABOUT 6 INCHES ALREADY ON THE GROUND AS OF 4 AM. INTENSE MESOSCALE BANDING SHOULD PERSIST INTO THE MORING HOURS AND POSSIBLY INTO THE AFTERNOON... THOUGH RATES WILL LIKELY SUBSIDE A BIT AFTER 18Z. WINDS... DOWNWARD MOMENTUM TRANSFER/MIXING OF A DEVELOPING 60-70KT LLJ WILL RESULT IN FREQUENT GUSTS ABOVE 50 MPH AND POTENTIALLY A FEW GUSTS TO 65 MPH. THE WORST OF THE WINDS WILL OCCUR FROM 12-22Z TODAY. ALL-IN-ALL...THE WELL ADVERTISED BLIZZARD IS COMING TO FRUITION FOR THE VAST MAJORITY OF THE PANHANDLES. THE ONLY LOCATIONS THAT WILL SEE REDUCED SNOWFALL AMOUNTS WILL BE THE FAR NW PANHANDLES...BUT VERY STRONG WINDS WILL BLOW AROUND ANY MINOR SNOWFALL ACCUMULATIONS AND STILL CREATE BRIEF BLIZZARD CONDITIONS. TUESDAY THROUGH SUNDAY... A COLD AND MAINLY DRY PERIOD WILL BE NOTED UNDER PREDOMINATELY NORTH WINDS. A FEW WEAK UPR WAVES COULD KICK OFF A FLURRY TUE NIGHT AND AGAIN THU...BUT NOTHING APPRECIABLE IS EXPECTED. WINDS MIGHT FINALLY SWING AROUND TO THE SOUTH SAT NIGHT AND SUN...BUT QUICKLY COME BACK TO THE NORTH BEHIND ANOTHER COLD FRONT ON SUNDAY NIGHT. SIMPSON FIRE WEATHER... ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE NOT EXPECTED THROUGH NEXT GIVEN THE EXPECTED SNOW COVER. SIMPSON && .AMA WATCHES/WARNINGS/ADVISORIES... TX...BLIZZARD WARNING UNTIL 3 AM CST TUESDAY FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH...DALLAM...DEAF SMITH... DONLEY...GRAY...HANSFORD...HARTLEY...HEMPHILL... HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE...OLDHAM... POTTER...RANDALL...ROBERTS...SHERMAN...WHEELER. OK...BLIZZARD WARNING UNTIL 3 AM CST TUESDAY FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. && $$ 06/14
AREA FORECAST DISCUSSION
NWS AMARILLO TX
1057 AM CST MON FEB 25 2013 .UPDATE... MADE MINOR ADJUSTMENTS TO THE SNOW AMOUNT GRIDS FROM NOON TO 6 PM TO ACCOUNT FOR HIGHER SNOWFALL RATES AS THE UPPER LOW LIFTS TO THE NORTH AND EAST. DURING THIS TIME FRAME 3 TO 6 ADDITIONAL INCHES OF SNOW WILL BE POSSIBLE ACROSS THE EASTERN OKLAHOMA AND TEXAS PANHANDLE AND THE SOUTH CENTRAL TEXAS PANHANDLE. && .PREV DISCUSSION... /ISSUED 833 AM CST MON FEB 25 2013/ ..CRIPPLING BLIZZARD ROARS ON... UPDATE... GOING FORECAST STILL ON TRACK. THE NWS OFFICE NOW HAS OVER 13 INCHES ON THE GROUND WITH 3-4 FOOT DRIFTS AND A MAX GUST TO 58 MPH. THE SE TX PANHANDLE HAS BEEN SLOW TO FILL IN WITH SNOW AFTER THE THUNDERSTORMS THAT DROPPED HEAVY RAIN LAST NIGHT AND THESE AREAS MIGHT END UP WITH AMOUNTS CLOSER TO THE 8 INCH SIDE THAN THE 14 INCH SIDE OF THEIR RANGE. AT THE END OF THE DAY...THE HEAVIEST TOTALS WILL ALMOST CERTAINLY BE ALONG A PALO DURO CANYON TO AMARILLO TO STINNETT TO PERRYTON LINE. SOME RECORDS SEEM TO BE IN A PRECARIOUS POSITION TODAY. THE FIRST IS AN ALL-TIME 24 HOUR SNOWFALL RECORD AT AMARILLO OF 20.6 INCHES FROM MARCH 25-26 1934. WE WILL LIKELY GET VERY CLOSE OR SURPASS THIS NUMBER BY THIS AFTERNOON. THE OTHER IS THE ALL-TIME STATE OF TEXAS 24 HOUR SNOWFALL RECORD OF 25 INCHES IN FOLLETT SET MARCH 28 2009. SOMEWHERE IN THE PERRYTON/STINNETT/BORGER/AMARILLO AREA COULD APPROACH THIS VALUE BY THIS AFTERNOON. SIMPSON PREV DISCUSSION... /ISSUED 541 AM CST MON FEB 25 2013/ AVIATION.../12Z TAFS/ VERY HAZARDOUS FLYING CONDITIONS EXPECTED TO CONTINUE THROUGH AT LEAST 00Z AT ALL TERMINALS. HEAVIEST SNOW AND LOWEST VISIBILITIES WILL BE AT KAMA 15-20Z. AWW REMAINS IN EFFECT FOR KAMA AND TRADEWINDS AIRPORT UNTIL 00Z. VFR CONDITIONS ARE EXPECTED TO RETURN TO ALL TERMINALS 00-02Z. NW WINDS ARE EXPECTED TO SUBSIDE BELOW 12 KT AT ALL TERMINALS BY 04Z. JACKSON PREV DISCUSSION... /ISSUED 446 AM CST MON FEB 25 2013/ SNOW PILING UP...WINDS INCREASING AND CREATING FULL FLEDGED BLIZZARD CONDITIONS AT THIS WRITING... DISCUSSION... MAIN CHANGE TO PREVIOUS FORECAST WAS TO ATTEMPT TO PIN POINT THE BAND OF HIGHEST SNOW TOTALS...WHICH WILL LIKELY STRETCH ALONG AN ARC FROM TULIA TO AMARILLO TO STINNETT TO SPEARMAN. LOCATIONS ON THIS ARC AND 30 MILES TO THE EAST AND WEST OF IT ARE SET TO RECEIVE AT LEAST A FOOT OF SNOW...WITH TOTALS UP TO 2 FEET NOT COMPLETELY OUT OF THE QUESTION. THE REST OF THE PANHANDLES WILL SEE SLIGHTLY LESSER AMOUNTS...BUT STILL BLIZZARD CONDITIONS. SEE THE BLIZZARD WARNING AND GRAPHICS ON WFO AMA HOMEPAGE AND FACEBOOK FOR A BETTER REPRESENTATION OF THIS EVENT THAN CAN BE TYPED IN BLOCK TEXT. THE NAM AND RUC HAVE DONE A GOOD JOB IN SHOWING A STRONG BAND OF FRONTOGENETICAL FORCING...THOUGH THE PLACEMENT HAS BEEN TOO FAR EAST. THIS BAND HAS SET UP OVER THE AFOREMENTIONED ARC AND CONVECTIVE ENHANCEMENT WITH RATES TO 2-3 INCHES PER HOUR HAVE BEEN NOTED. IN FACT...WE HAVE OBSERVED AT LEAST A HALF DOZEN CLOUD TO GROUND STRIKES AT THE NWS AMA OFFICE OVERNIGHT...WITH ABOUT 6 INCHES ALREADY ON THE GROUND AS OF 4 AM. INTENSE MESOSCALE BANDING SHOULD PERSIST INTO THE MORING HOURS AND POSSIBLY INTO THE AFTERNOON... THOUGH RATES WILL LIKELY SUBSIDE A BIT AFTER 18Z. WINDS... DOWNWARD MOMENTUM TRANSFER/MIXING OF A DEVELOPING 60-70KT LLJ WILL RESULT IN FREQUENT GUSTS ABOVE 50 MPH AND POTENTIALLY A FEW GUSTS TO 65 MPH. THE WORST OF THE WINDS WILL OCCUR FROM 12-22Z TODAY. ALL-IN-ALL...THE WELL ADVERTISED BLIZZARD IS COMING TO FRUITION FOR THE VAST MAJORITY OF THE PANHANDLES. THE ONLY LOCATIONS THAT WILL SEE REDUCED SNOWFALL AMOUNTS WILL BE THE FAR NW PANHANDLES...BUT VERY STRONG WINDS WILL BLOW AROUND ANY MINOR SNOWFALL ACCUMULATIONS AND STILL CREATE BRIEF BLIZZARD CONDITIONS. TUESDAY THROUGH SUNDAY... A COLD AND MAINLY DRY PERIOD WILL BE NOTED UNDER PREDOMINATELY NORTH WINDS. A FEW WEAK UPR WAVES COULD KICK OFF A FLURRY TUE NIGHT AND AGAIN THU...BUT NOTHING APPRECIABLE IS EXPECTED. WINDS MIGHT FINALLY SWING AROUND TO THE SOUTH SAT NIGHT AND SUN...BUT QUICKLY COME BACK TO THE NORTH BEHIND ANOTHER COLD FRONT ON SUNDAY NIGHT. SIMPSON FIRE WEATHER... ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE NOT EXPECTED THROUGH NEXT GIVEN THE EXPECTED SNOW COVER. SIMPSON && .AMA WATCHES/WARNINGS/ADVISORIES... TX...BLIZZARD WARNING UNTIL 3 AM CST TUESDAY FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH...DALLAM...DEAF SMITH... DONLEY...GRAY...HANSFORD...HARTLEY...HEMPHILL... HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE...OLDHAM... POTTER...RANDALL...ROBERTS...SHERMAN...WHEELER. OK...BLIZZARD WARNING UNTIL 3 AM CST TUESDAY FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. && $$ 99/14
AREA FORECAST DISCUSSION
NWS AMARILLO TX
833 AM CST MON FEB 25 2013 ...CRIPPLING BLIZZARD ROARS ON... .UPDATE... GOING FORECAST STILL ON TRACK. THE NWS OFFICE NOW HAS OVER 13 INCHES ON THE GROUND WITH 3-4 FOOT DRIFTS AND A MAX GUST TO 58 MPH. THE SE TX PANHANDLE HAS BEEN SLOW TO FILL IN WITH SNOW AFTER THE THUNDERSTORMS THAT DROPPED HEAVY RAIN LAST NIGHT AND THESE AREAS MIGHT END UP WITH AMOUNTS CLOSER TO THE 8 INCH SIDE THAN THE 14 INCH SIDE OF THEIR RANGE. AT THE END OF THE DAY...THE HEAVIEST TOTALS WILL ALMOST CERTAINLY BE ALONG A PALO DURO CANYON TO AMARILLO TO STINNETT TO PERRYTON LINE. SOME RECORDS SEEM TO BE IN A PRECARIOUS POSITION TODAY. THE FIRST IS AN ALL-TIME 24 HOUR SNOWFALL RECORD AT AMARILLO OF 20.6 INCHES FROM MARCH 25-26 1934. WE WILL LIKELY GET VERY CLOSE OR SURPASS THIS NUMBER BY THIS AFTERNOON. THE OTHER IS THE ALL-TIME STATE OF TEXAS 24 HOUR SNOWFALL RECORD OF 25 INCHES IN FOLLETT SET MARCH 28 2009. SOMEWHERE IN THE PERRYTON/STINNETT/BORGER/AMARILLO AREA COULD APPROACH THIS VALUE BY THIS AFTERNOON. SIMPSON && .PREV DISCUSSION... /ISSUED 541 AM CST MON FEB 25 2013/ AVIATION.../12Z TAFS/ VERY HAZARDOUS FLYING CONDITIONS EXPECTED TO CONTINUE THROUGH AT LEAST 00Z AT ALL TERMINALS. HEAVIEST SNOW AND LOWEST VISIBILITIES WILL BE AT KAMA 15-20Z. AWW REMAINS IN EFFECT FOR KAMA AND TRADEWINDS AIRPORT UNTIL 00Z. VFR CONDITIONS ARE EXPECTED TO RETURN TO ALL TERMINALS 00-02Z. NW WINDS ARE EXPECTED TO SUBSIDE BELOW 12 KT AT ALL TERMINALS BY 04Z. JACKSON PREV DISCUSSION... /ISSUED 446 AM CST MON FEB 25 2013/ .SNOW PILING UP...WINDS INCREASING AND CREATING FULL FLEDGED BLIZZARD CONDITIONS AT THIS WRITING... DISCUSSION... MAIN CHANGE TO PREVIOUS FORECAST WAS TO ATTEMPT TO PIN POINT THE BAND OF HIGHEST SNOW TOTALS...WHICH WILL LIKELY STRETCH ALONG AN ARC FROM TULIA TO AMARILLO TO STINNETT TO SPEARMAN. LOCATIONS ON THIS ARC AND 30 MILES TO THE EAST AND WEST OF IT ARE SET TO RECEIVE AT LEAST A FOOT OF SNOW...WITH TOTALS UP TO 2 FEET NOT COMPLETELY OUT OF THE QUESTION. THE REST OF THE PANHANDLES WILL SEE SLIGHTLY LESSER AMOUNTS...BUT STILL BLIZZARD CONDITIONS. SEE THE BLIZZARD WARNING AND GRAPHICS ON WFO AMA HOMEPAGE AND FACEBOOK FOR A BETTER REPRESENTATION OF THIS EVENT THAN CAN BE TYPED IN BLOCK TEXT. THE NAM AND RUC HAVE DONE A GOOD JOB IN SHOWING A STRONG BAND OF FRONTOGENETICAL FORCING...THOUGH THE PLACEMENT HAS BEEN TOO FAR EAST. THIS BAND HAS SET UP OVER THE AFOREMENTIONED ARC AND CONVECTIVE ENHANCEMENT WITH RATES TO 2-3 INCHES PER HOUR HAVE BEEN NOTED. IN FACT...WE HAVE OBSERVED AT LEAST A HALF DOZEN CLOUD TO GROUND STRIKES AT THE NWS AMA OFFICE OVERNIGHT...WITH ABOUT 6 INCHES ALREADY ON THE GROUND AS OF 4 AM. INTENSE MESOSCALE BANDING SHOULD PERSIST INTO THE MORING HOURS AND POSSIBLY INTO THE AFTERNOON... THOUGH RATES WILL LIKELY SUBSIDE A BIT AFTER 18Z. WINDS... DOWNWARD MOMENTUM TRANSFER/MIXING OF A DEVELOPING 60-70KT LLJ WILL RESULT IN FREQUENT GUSTS ABOVE 50 MPH AND POTENTIALLY A FEW GUSTS TO 65 MPH. THE WORST OF THE WINDS WILL OCCUR FROM 12-22Z TODAY. ALL-IN-ALL...THE WELL ADVERTISED BLIZZARD IS COMING TO FRUITION FOR THE VAST MAJORITY OF THE PANHANDLES. THE ONLY LOCATIONS THAT WILL SEE REDUCED SNOWFALL AMOUNTS WILL BE THE FAR NW PANHANDLES...BUT VERY STRONG WINDS WILL BLOW AROUND ANY MINOR SNOWFALL ACCUMULATIONS AND STILL CREATE BRIEF BLIZZARD CONDITIONS. TUESDAY THROUGH SUNDAY... A COLD AND MAINLY DRY PERIOD WILL BE NOTED UNDER PREDOMINATELY NORTH WINDS. A FEW WEAK UPR WAVES COULD KICK OFF A FLURRY TUE NIGHT AND AGAIN THU...BUT NOTHING APPRECIABLE IS EXPECTED. WINDS MIGHT FINALLY SWING AROUND TO THE SOUTH SAT NIGHT AND SUN...BUT QUICKLY COME BACK TO THE NORTH BEHIND ANOTHER COLD FRONT ON SUNDAY NIGHT. SIMPSON FIRE WEATHER... ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE NOT EXPECTED THROUGH NEXT GIVEN THE EXPECTED SNOW COVER. SIMPSON && .AMA WATCHES/WARNINGS/ADVISORIES... TX...BLIZZARD WARNING UNTIL 3 AM CST TUESDAY FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH...DALLAM...DEAF SMITH... DONLEY...GRAY...HANSFORD...HARTLEY...HEMPHILL... HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE...OLDHAM... POTTER...RANDALL...ROBERTS...SHERMAN...WHEELER. OK...BLIZZARD WARNING UNTIL 3 AM CST TUESDAY FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. && $$ 13/09
AREA FORECAST DISCUSSION...UPDATED
NWS AMARILLO TX
541 AM CST MON FEB 25 2013 .AVIATION.../12Z TAFS/ VERY HAZARDOUS FLYING CONDITIONS EXPECTED TO CONTINUE THROUGH AT LEAST 00Z AT ALL TERMINALS. HEAVIEST SNOW AND LOWEST VISIBILITIES WILL BE AT KAMA 15-20Z. AWW REMAINS IN EFFECT FOR KAMA AND TRADEWINDS AIRPORT UNTIL 00Z. VFR CONDITIONS ARE EXPECTED TO RETURN TO ALL TERMINALS 00-02Z. NW WINDS ARE EXPECTED TO SUBSIDE BELOW 12 KT AT ALL TERMINALS BY 04Z. JACKSON && .PREV DISCUSSION... /ISSUED 446 AM CST MON FEB 25 2013/ ..SNOW PILING UP...WINDS INCREASING AND CREATING FULL FLEDGED BLIZZARD CONDITIONS AT THIS WRITING... DISCUSSION... MAIN CHANGE TO PREVIOUS FORECAST WAS TO ATTEMPT TO PIN POINT THE BAND OF HIGHEST SNOW TOTALS...WHICH WILL LIKELY STRETCH ALONG AN ARC FROM TULIA TO AMARILLO TO STINNETT TO SPEARMAN. LOCATIONS ON THIS ARC AND 30 MILES TO THE EAST AND WEST OF IT ARE SET TO RECEIVE AT LEAST A FOOT OF SNOW...WITH TOTALS UP TO 2 FEET NOT COMPLETELY OUT OF THE QUESTION. THE REST OF THE PANHANDLES WILL SEE SLIGHTLY LESSER AMOUNTS...BUT STILL BLIZZARD CONDITIONS. SEE THE BLIZZARD WARNING AND GRAPHICS ON WFO AMA HOMEPAGE AND FACEBOOK FOR A BETTER REPRESENTATION OF THIS EVENT THAN CAN BE TYPED IN BLOCK TEXT. THE NAM AND RUC HAVE DONE A GOOD JOB IN SHOWING A STRONG BAND OF FRONTOGENETICAL FORCING...THOUGH THE PLACEMENT HAS BEEN TOO FAR EAST. THIS BAND HAS SET UP OVER THE AFOREMENTIONED ARC AND CONVECTIVE ENHANCEMENT WITH RATES TO 2-3 INCHES PER HOUR HAVE BEEN NOTED. IN FACT...WE HAVE OBSERVED AT LEAST A HALF DOZEN CLOUD TO GROUND STRIKES AT THE NWS AMA OFFICE OVERNIGHT...WITH ABOUT 6 INCHES ALREADY ON THE GROUND AS OF 4 AM. INTENSE MESOSCALE BANDING SHOULD PERSIST INTO THE MORING HOURS AND POSSIBLY INTO THE AFTERNOON... THOUGH RATES WILL LIKELY SUBSIDE A BIT AFTER 18Z. WINDS... DOWNWARD MOMENTUM TRANSFER/MIXING OF A DEVELOPING 60-70KT LLJ WILL RESULT IN FREQUENT GUSTS ABOVE 50 MPH AND POTENTIALLY A FEW GUSTS TO 65 MPH. THE WORST OF THE WINDS WILL OCCUR FROM 12-22Z TODAY. ALL-IN-ALL...THE WELL ADVERTISED BLIZZARD IS COMING TO FRUITION FOR THE VAST MAJORITY OF THE PANHANDLES. THE ONLY LOCATIONS THAT WILL SEE REDUCED SNOWFALL AMOUNTS WILL BE THE FAR NW PANHANDLES...BUT VERY STRONG WINDS WILL BLOW AROUND ANY MINOR SNOWFALL ACCUMULATIONS AND STILL CREATE BRIEF BLIZZARD CONDITIONS. TUESDAY THROUGH SUNDAY... A COLD AND MAINLY DRY PERIOD WILL BE NOTED UNDER PREDOMINATELY NORTH WINDS. A FEW WEAK UPR WAVES COULD KICK OFF A FLURRY TUE NIGHT AND AGAIN THU...BUT NOTHING APPRECIABLE IS EXPECTED. WINDS MIGHT FINALLY SWING AROUND TO THE SOUTH SAT NIGHT AND SUN...BUT QUICKLY COME BACK TO THE NORTH BEHIND ANOTHER COLD FRONT ON SUNDAY NIGHT. SIMPSON FIRE WEATHER... ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE NOT EXPECTED THROUGH NEXT GIVEN THE EXPECTED SNOW COVER. SIMPSON && .AMA WATCHES/WARNINGS/ADVISORIES... TX...BLIZZARD WARNING UNTIL 3 AM CST TUESDAY FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH...DALLAM...DEAF SMITH... DONLEY...GRAY...HANSFORD...HARTLEY...HEMPHILL... HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE...OLDHAM... POTTER...RANDALL...ROBERTS...SHERMAN...WHEELER. OK...BLIZZARD WARNING UNTIL 3 AM CST TUESDAY FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. && $$ JJ/BJS
AREA FORECAST DISCUSSION
NWS AMARILLO TX
446 AM CST MON FEB 25 2013 ...SNOW PILING UP...WINDS INCREASING AND CREATING FULL FLEDGED BLIZZARD CONDITIONS AT THIS WRITING... .DISCUSSION... MAIN CHANGE TO PREVIOUS FORECAST WAS TO ATTEMPT TO PIN POINT THE BAND OF HIGHEST SNOW TOTALS...WHICH WILL LIKELY STRETCH ALONG AN ARC FROM TULIA TO AMARILLO TO STINNETT TO SPEARMAN. LOCATIONS ON THIS ARC AND 30 MILES TO THE EAST AND WEST OF IT ARE SET TO RECEIVE AT LEAST A FOOT OF SNOW...WITH TOTALS UP TO 2 FEET NOT COMPLETELY OUT OF THE QUESTION. THE REST OF THE PANHANDLES WILL SEE SLIGHTLY LESSER AMOUNTS...BUT STILL BLIZZARD CONDITIONS. SEE THE BLIZZARD WARNING AND GRAPHICS ON WFO AMA HOMEPAGE AND FACEBOOK FOR A BETTER REPRESENTATION OF THIS EVENT THAN CAN BE TYPED IN BLOCK TEXT. THE NAM AND RUC HAVE DONE A GOOD JOB IN SHOWING A STRONG BAND OF FRONTOGENETICAL FORCING...THOUGH THE PLACEMENT HAS BEEN TOO FAR EAST. THIS BAND HAS SET UP OVER THE AFOREMENTIONED ARC AND CONVECTIVE ENHANCEMENT WITH RATES TO 2-3 INCHES PER HOUR HAVE BEEN NOTED. IN FACT...WE HAVE OBSERVED AT LEAST A HALF DOZEN CLOUD TO GROUND STRIKES AT THE NWS AMA OFFICE OVERNIGHT...WITH ABOUT 6 INCHES ALREADY ON THE GROUND AS OF 4 AM. INTENSE MESOSCALE BANDING SHOULD PERSIST INTO THE MORING HOURS AND POSSIBLY INTO THE AFTERNOON... THOUGH RATES WILL LIKELY SUBSIDE A BIT AFTER 18Z. WINDS... DOWNWARD MOMENTUM TRANSFER/MIXING OF A DEVELOPING 60-70KT LLJ WILL RESULT IN FREQUENT GUSTS ABOVE 50 MPH AND POTENTIALLY A FEW GUSTS TO 65 MPH. THE WORST OF THE WINDS WILL OCCUR FROM 12-22Z TODAY. ALL-IN-ALL...THE WELL ADVERTISED BLIZZARD IS COMING TO FRUITION FOR THE VAST MAJORITY OF THE PANHANDLES. THE ONLY LOCATIONS THAT WILL SEE REDUCED SNOWFALL AMOUNTS WILL BE THE FAR NW PANHANDLES...BUT VERY STRONG WINDS WILL BLOW AROUND ANY MINOR SNOWFALL ACCUMULATIONS AND STILL CREATE BRIEF BLIZZARD CONDITIONS. TUESDAY THROUGH SUNDAY... A COLD AND MAINLY DRY PERIOD WILL BE NOTED UNDER PREDOMINATELY NORTH WINDS. A FEW WEAK UPR WAVES COULD KICK OFF A FLURRY TUE NIGHT AND AGAIN THU...BUT NOTHING APPRECIABLE IS EXPECTED. WINDS MIGHT FINALLY SWING AROUND TO THE SOUTH SAT NIGHT AND SUN...BUT QUICKLY COME BACK TO THE NORTH BEHIND ANOTHER COLD FRONT ON SUNDAY NIGHT. SIMPSON && .FIRE WEATHER... ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE NOT EXPECTED THROUGH NEXT GIVEN THE EXPECTED SNOW COVER. SIMPSON && .PRELIMINARY POINT TEMPS/POPS... AMARILLO TX 30 12 35 18 38 / 100 20 5 20 5 BEAVER OK 30 4 35 18 34 / 100 60 5 10 5 BOISE CITY OK 34 12 40 16 35 / 70 5 5 20 5 BORGER TX 32 9 35 21 38 / 100 30 5 20 5 BOYS RANCH TX 34 8 40 21 40 / 100 10 5 20 5 CANYON TX 32 11 35 18 39 / 100 10 5 20 5 CLARENDON TX 31 17 35 22 39 / 100 30 5 10 5 DALHART TX 35 7 40 15 39 / 90 5 5 20 5 GUYMON OK 32 7 37 17 38 / 100 20 5 20 5 HEREFORD TX 33 9 38 18 39 / 100 5 5 20 5 LIPSCOMB TX 32 11 33 20 34 / 100 60 5 10 5 PAMPA TX 27 9 34 19 35 / 100 40 5 20 5 SHAMROCK TX 31 19 35 21 37 / 100 50 5 10 5 WELLINGTON TX 32 21 36 24 40 / 100 40 5 10 5 && .AMA WATCHES/WARNINGS/ADVISORIES... TX...BLIZZARD WARNING UNTIL 3 AM CST TUESDAY FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH...DALLAM...DEAF SMITH... DONLEY...GRAY...HANSFORD...HARTLEY...HEMPHILL... HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE...OLDHAM... POTTER...RANDALL...ROBERTS...SHERMAN...WHEELER. OK...BLIZZARD WARNING UNTIL 3 AM CST TUESDAY FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. && $$ 13/09
AREA FORECAST DISCUSSION
NWS SPOKANE WA
942 PM PST Sun Feb 24 2013 .SYNOPSIS...A winter storm system will affect the Inland Northwest tonight into Monday, with accumulating snows and breezy winds expected over most locations. Another quick-moving, weaker system will affect the region midweek. Warmer weather will make an appearance late this week, with Spring-like temperatures expected. && .DISCUSSION... Little if any changes made to current forecast. Majority of significant precipitation begins roughly near 7Z near the cascades and more toward 9-10Z for the Spokane area per the most recent HRRR solutions and the grids and forecast already had a good handle on that. Other issues of note would be the increase in post frontal winds as the surface low passing near the Southern British Columbia border along with the cold front passage increase the pressure gradient. Perhaps may increase wind near the Waterville Plateau a bit more upon further scrutiny toward near Advisory wind gusts amounts. /Pelatti && .AVIATION... 06Z TAFS: A storm system will bring mostly snow as far as precipitation goes to all TAF sites tonight and continuing into tomorrow morning. Ceilings associated with the snow should lower to MVFR/IFR. Wind should increase and be gusty to 30KTS and perhaps some speed shear type low level wind shear may occur in the vicinity of east slopes of the Cascades and into some of the lowlands overnight into tomorrow morning as well. /Pelatti && .PRELIMINARY POINT TEMPS/POPS... Spokane 31 41 26 38 28 40 / 60 100 20 0 20 30 Coeur d`Alene 31 38 27 38 26 40 / 50 100 30 10 20 40 Pullman 31 39 27 39 28 42 / 40 100 30 10 10 40 Lewiston 34 48 32 48 32 50 / 20 70 20 0 10 30 Colville 31 41 27 43 26 44 / 80 100 30 10 30 50 Sandpoint 32 37 28 37 24 37 / 60 100 60 10 20 60 Kellogg 30 34 27 36 24 39 / 40 100 80 20 20 60 Moses Lake 33 48 27 48 30 49 / 60 20 0 0 10 10 Wenatchee 31 44 28 46 31 47 / 60 20 10 0 10 10 Omak 25 38 22 37 24 42 / 80 60 0 10 40 20 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Winter Weather Advisory from 4 AM to 10 PM PST Monday for Central Panhandle Mountains. Winter Weather Advisory until 10 AM PST Monday for Coeur d`Alene Area-Idaho Palouse. Winter Weather Advisory until 10 AM PST Monday for Northern Panhandle. WA...Winter Weather Advisory until 10 AM PST Monday for Spokane Area- Washington Palouse. Winter Weather Advisory until 10 AM PST Monday for Northeast Mountains-Okanogan Highlands. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1059 AM CST MON FEB 25 2013 .SHORT TERM...UPDATE THROUGH THIS AFTERNOON 1031 AM CST MON FEB 25 2013 WATER VAPOR SATELLITE IMAGERY SHOWS A MID-LEVEL TROUGH PUSHING EAST ACROSS MN AT THIS TIME. RAP SHOWING SOME WEAK ISENTROPIC UPGLIDE ON THE 285K SURFACE BETWEEN 850-750MB INTO THIS AFTERNOON MAINLY ACROSS NORTHEAST IA INTO SOUTHWEST WI IN RESPONSE TO THIS WAVE. PERIODIC/VERY LIGHT SNOW FALLING IN RESPONSE TO THIS LIFT WITH CHARLES CITY IA REPORTING A VERY LIGHT DUSTING THIS PAST HOUR. HAVE ADJUSTED FORECAST ACCORDINGLY TO REFLECT THIS SCENARIO INTO THE AFTERNOON HOURS. .LONG TERM...THURSDAY THROUGH SUNDAY 320 AM CST MON FEB 25 2013 AFTER THE SYSTEM MOVES OFF TO THE EAST COAST BY MID WEEK...A BROAD RIDGE OF HIGH PRESSURE WILL EXTEND DOWN FROM NORTH CENTRAL CANADA DOWN TO THE GULF COAST AND REMAIN ACROSS THE UPPER MISSISSIPPI RIVER VALLEY REGION INTO NEXT WEEKEND. WHILE THE LOW TO UPPER LEVEL FLOW WILL BE OUT OF THE NORTH...THERE IS NOT MUCH OF A COLD SOURCE TO PULL FROM OUT OF CENTRAL CANADA...SO TEMPERATURES SHOULD NOT TAKE MUCH OF A HIT THROUGH THE WEEK. CLEARING SKIES AND AN INCREASING SUN ANGLE WILL HELP AS WELL TO KEEP TEMPERATURES NEAR NORMAL. && .AVIATION...THROUGH 18Z TUESDAY 1058 AM CST MON FEB 25 2013 FAIRLY DIFFICULT FORECAST THROUGH THE NEXT 24 HOURS WITH REGARD TO LOW CLOUD/FOG POTENTIAL. CURRENTLY THERE IS A MID-LEVEL WAVE PUSHING EAST ACROSS THE AREA AND THIS HAS BEEN RESPONSIBLE FOR SOME PERIODIC VERY LIGHT SNOW IN WEAK ISENTROPIC UPGLIDE. OTHERWISE...VIS/3.9MICRON IMAGERY SURFACE OBSERVATIONS SHOWING QUITE A BIT OF IFR/LIFR STRATUS AND FOG OUT ACROSS SOUTH CENTRAL MN/WESTERN IA. EASTERN PERIPHERY OF THIS WAS UNCOMFORTABLY CLOSE TO KRST TAF SITE. THINKING WITH THE SURFACE RIDGE AXIS LAYING UP W-E ACROSS THE AREA INTO THIS EVENING ALONG WITH PARTIAL SNOWMELT LOADING THE LOWER BOUNDARY LAYER WITH ADDITIONAL MOISTURE...POTENTIAL IS SETTING UP FOR SOME IFR/LIFR CONDITIONS AT LEAST ACROSS SOUTHEAST MN INCLUDING THE KRST TAF SITE. DON/T THINK THAT KLSE WILL BE AS BAD AND PLANNING ON CARRYING MVFR CONDITIONS GOING INTO THIS EVENING. LOW PRESSURE SYSTEM MOVING ACROSS THE SOUTHERN PLAINS INTO THE BOOTHEEL REGION OF MO OVERNIGHT WILL BRING AN INCREASING/DRIER LOW LEVEL FLOW INTO THE AREA AFTER MIDNIGHT AND THINKING THAT THIS WILL IMPROVE CONDITIONS INTO VFR RANGE. WILL TAKE A CLOSER LOOK AT EVERYTHING BEFORE SENDING OUT FINALIZED 18Z TAFS. && .ARX WATCHES/WARNINGS/ADVISORIES... 320 AM CST MON FEB 25 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM....HALBACH AVIATION...DAS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
530 AM CST MON FEB 25 2013 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT 230 AM CST MON FEB 25 2013 THE MAIN FOCUS THROUGH THE NEXT FEW DAYS IS ON THE SNOW POTENTIAL...PARTICULARLY ON TUESDAY AS A LOW PRESSURE SYSTEM TRACKS TO THE SOUTH OF THE REGION. CURRENTLY TRACKING SOME SPOTTY LIGHT SNOW THAT HAS DEVELOPED ALONG AN INVERTED SURFACE TROUGH AND AHEAD OF A MID LEVEL SHORTWAVE TROUGH PUSHING INTO WESTERN MINNESOTA. THIS SNOW IS RUNNING INTO AN AREA OF DRIER AIR AT THE SURFACE DUE TO A RIDGE AXIS THAT RUNS ACROSS THE SOUTHERN GREAT LAKES TOWARD CENTRAL MINNESOTA. 25.07Z RAP SOUNDINGS FROM ACROSS SOUTHEAST MINNESOTA INTO WESTERN WISCONSIN SHOW A DEEPENING SATURATED LAYER THAT COINCIDES WITH THE WEAK TO MODERATE LIFT FROM LOW LEVEL FRONTOGENESIS THIS MORNING AND SHOULD HELP TO PROMOTE THE DEVELOPMENT OF THE LIGHT SNOW. VISIBILITY HAS MAINLY BEEN IN THE 3-6SM RANGE ACROSS SOUTHEAST MINNESOTA SO FAR THIS MORNING...BUT THERE HAVE BEEN TIMES WHEN IT HAS DROPPED TO LESS THAN 2SM. REPORTS SO FAR FROM THIS AREA HAVE BEEN THAT THERE HAS JUST BEEN A TRACE TO PERHAPS A TENTH OR TWO OF SNOW ACCUMULATION. 25.00Z MESO-MODELS SUGGEST THAT THIS BAND WILL LIFT TO THE NORTHEAST THIS MORNING TOWARD GREEN BAY AND GENERALLY DISSIPATE IN COVERAGE AS THE LIFT WEAKENS. STILL KEPT SOME SMALL CHANCES IN THROUGH 18Z WITH JUST THE TENTH OR TWO OF ACCUMULATION EXPECTED. THE MAIN CONCERN IS JUST THE TIMING OF IT COMING IN RIGHT BEFORE THIS MORNINGS COMMUTE WHICH COULD MAKE FOR A FEW SLICK SPOTS IF IT CAN ACCUMULATE. THE 25.07Z RAP SOUNDINGS ALSO INDICATE A POSSIBLE LOSS OF ICE LATER THIS MORNING...BUT THINK THAT THE FORCING WILL HAVE CEASED AT THAT POINT AND IS LIKELY THE REASON THE MID LEVEL SATURATION ENDS. AS THE INVERTED SURFACE TROUGH WASHES OUT TODAY AND THE NEXT SYSTEM TRACKS THROUGH THE OZARKS...THE SURFACE RIDGE AXIS WILL LIFT NORTH OF THE REGION AND SHOULD KEEP ANY OF THE POTENTIAL FOG THERE AS WELL. THE DRY LOW LEVEL AIR IN PLACE FROM THE RIDGE IS ONE OF THE CONCERNS GOING INTO THE NEXT SYSTEM ON TUESDAY AND HOW FAST THE COLUMN WILL BE ABLE TO SATURATE OUT. CONFIDENCE REMAINS SOMEWHAT LOW IN HOW THE SYSTEM ON TUESDAY WILL PAN OUT...BUT THE TREND STILL APPEARS TO BE FOR A SOUTHERN TRACK THAT MAY KEEP MUCH OF THE FORECAST AREA ON THE DRY SIDE. THE 25.00Z NAM IS A CONSIDERABLE OUTLIER WITH ITS TRACK TO THE NORTH AND HAS BEEN CORRECTED WITH THE 25.06Z RUN. 25.00Z GFS/25.06Z NAM BUFKIT SOUNDINGS SHOW A DRY LAYER BETWEEN 900MB AND 700MB THAT WILL TAKE SOME TIME TO SATURATE OUT AS THE SYSTEM APPROACHES FROM THE SOUTHWEST. HAVE REALLY SLOWED DOWN THE TIMING OF THE SNOW MOVING IN ON TUESDAY FROM THE SOUTH AS THE DRY AIR APPEARS TO WIN OUT FOR MUCH OF THE DAY. THROUGH 00Z WEDNESDAY...THE BEST CHANCES FOR ANY SNOW APPEAR TO BE IN CLAYTON/GRANT COUNTIES...THOUGH THE ONLY 25.00Z MODEL THAT HAS ANY SNOW IN THERE BY THAT TIME IS THE GFS WHICH IS NOTORIOUSLY HIGH ON ITS HUMIDITY AT TIMES. THUS...MORE ADJUSTMENTS MAY BE NEEDED IN FORECAST AS CONFIDENCE INCREASES THAT THE SNOW WILL NOT OCCUR. THIS 12Z TUESDAY THROUGH 00Z WEDNESDAY PERIOD IS CRUCIAL BECAUSE IT IS GOING TO BE THE MAIN TIME FRAME FOR ANY DECENT SNOWFALL ACCUMULATION. AFTER 00Z WEDNESDAY...THE SYSTEM LOSES A LOT OF ITS DEEP/STRONG FORCING AS THE LOW FILLS INTO THE NIGHT. FOR NOW...HAVE MAINTAINED SOME 2-4 INCH SNOW AMOUNTS FOR CLAYTON/GRANT COUNTY WITH LESS THAN 2 INCHES NORTHWEST OF THERE TUESDAY INTO TUESDAY NIGHT...BUT AS MENTIONED...CONFIDENCE IN THIS OCCURRING IS FAIRLY LOW AND BASED ON THIS WOULD NOT THINK THAT AN ADVISORY IS GOING TO BE NEEDED. HOW LONG THE LIGHT SNOW MAY LINGER IS ALSO IN QUESTION AS 25.00Z GFS/25.06Z NAM BUFKIT SOUNDINGS SHOW WEAK LIFT AND DIMINISHING SATURATION OF THE COLUMN INTO WEDNESDAY NIGHT. MAINTAINED SOME CHANCES OF SOME LIGHT SNOW WITH THE HIGHEST CHANCES ACROSS SOUTHWEST WISCONSIN AND NORTHEAST IOWA WHERE THE CORE OF THE UPPER LEVEL LOW WILL TRACK ACROSS. ANY SNOW AMOUNTS OVER THIS PERIOD WOULD BE LIGHT AT LESS THAN AN INCH. .LONG TERM...THURSDAY THROUGH SUNDAY 320 AM CST MON FEB 25 2013 AFTER THE SYSTEM MOVES OFF TO THE EAST COAST BY MID WEEK...A BROAD RIDGE OF HIGH PRESSURE WILL EXTEND DOWN FROM NORTH CENTRAL CANADA DOWN TO THE GULF COAST AND REMAIN ACROSS THE UPPER MISSISSIPPI RIVER VALLEY REGION INTO NEXT WEEKEND. WHILE THE LOW TO UPPER LEVEL FLOW WILL BE OUT OF THE NORTH...THERE IS NOT MUCH OF A COLD SOURCE TO PULL FROM OUT OF CENTRAL CANADA...SO TEMPERATURES SHOULD NOT TAKE MUCH OF A HIT THROUGH THE WEEK. CLEARING SKIES AND AN INCREASING SUN ANGLE WILL HELP AS WELL TO KEEP TEMPERATURES NEAR NORMAL. && .AVIATION...TODAY AND TONIGHT 530 AM CST MON FEB 25 2013 CLOUDS WILL BE THE RULE ACROSS THE TAF SITES TODAY/TONIGHT...BUT MOSTLY BE AOA 3500 FT AS THE LOWER LEVEL AIRMASS ACROSS THE AREA REMAINS ON THE DRY SIDE. DUE TO A MORE MOIST BOUNDARY LAYER AND WEAK GRADIENT/LIGHT WINDS...SOME MVFR VSBYS IN BR WILL PREVAIL ACROSS THE HIGHER TERRAIN AREAS OF NORTHEAST IA/SOUTHEAST MN THRU MUCH OF THIS MORNING. WEAK FORCING/LIFT WILL CONTINUE TO SPREAD ACROSS THE AREA EARLY THIS MORNING. THIS LIFT WAS PRODUCING SOME -SN AROUND KLSE INTO WESTERN WI. AS THE LIFT WEAKENS/EXITS BY MID MORNING THIS -SN WILL EXIT EAST OF THE KLSE AREA...WITH VFR VSBYS THEN EXPECTED TO PREVAIL AT BOTH KRST/KLSE FOR THE LATE MORNING HOURS AND THRU TONIGHT. CLOUD COVER TONIGHT...AHEAD OF THE SYSTEM LIFTING OUT OF THE SOUTHERN PLAINS...ALONG WITH INCREASING NORTHEAST WINDS AS THE SFC LOW LIFTS INTO SOUTHERN MO...ARE EXPECTED TO PREVENT ANY MVFR BR DEVELOPMENT TONIGHT INTO TUE MORNING. && .ARX WATCHES/WARNINGS/ADVISORIES... 320 AM CST MON FEB 25 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM....HALBACH AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
320 AM CST MON FEB 25 2013 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT 230 AM CST MON FEB 25 2013 THE MAIN FOCUS THROUGH THE NEXT FEW DAYS IS ON THE SNOW POTENTIAL...PARTICULARLY ON TUESDAY AS A LOW PRESSURE SYSTEM TRACKS TO THE SOUTH OF THE REGION. CURRENTLY TRACKING SOME SPOTTY LIGHT SNOW THAT HAS DEVELOPED ALONG AN INVERTED SURFACE TROUGH AND AHEAD OF A MID LEVEL SHORTWAVE TROUGH PUSHING INTO WESTERN MINNESOTA. THIS SNOW IS RUNNING INTO AN AREA OF DRIER AIR AT THE SURFACE DUE TO A RIDGE AXIS THAT RUNS ACROSS THE SOUTHERN GREAT LAKES TOWARD CENTRAL MINNESOTA. 25.07Z RAP SOUNDINGS FROM ACROSS SOUTHEAST MINNESOTA INTO WESTERN WISCONSIN SHOW A DEEPENING SATURATED LAYER THAT COINCIDES WITH THE WEAK TO MODERATE LIFT FROM LOW LEVEL FRONTOGENESIS THIS MORNING AND SHOULD HELP TO PROMOTE THE DEVELOPMENT OF THE LIGHT SNOW. VISIBILITY HAS MAINLY BEEN IN THE 3-6SM RANGE ACROSS SOUTHEAST MINNESOTA SO FAR THIS MORNING...BUT THERE HAVE BEEN TIMES WHEN IT HAS DROPPED TO LESS THAN 2SM. REPORTS SO FAR FROM THIS AREA HAVE BEEN THAT THERE HAS JUST BEEN A TRACE TO PERHAPS A TENTH OR TWO OF SNOW ACCUMULATION. 25.00Z MESO-MODELS SUGGEST THAT THIS BAND WILL LIFT TO THE NORTHEAST THIS MORNING TOWARD GREEN BAY AND GENERALLY DISSIPATE IN COVERAGE AS THE LIFT WEAKENS. STILL KEPT SOME SMALL CHANCES IN THROUGH 18Z WITH JUST THE TENTH OR TWO OF ACCUMULATION EXPECTED. THE MAIN CONCERN IS JUST THE TIMING OF IT COMING IN RIGHT BEFORE THIS MORNINGS COMMUTE WHICH COULD MAKE FOR A FEW SLICK SPOTS IF IT CAN ACCUMULATE. THE 25.07Z RAP SOUNDINGS ALSO INDICATE A POSSIBLE LOSS OF ICE LATER THIS MORNING...BUT THINK THAT THE FORCING WILL HAVE CEASED AT THAT POINT AND IS LIKELY THE REASON THE MID LEVEL SATURATION ENDS. AS THE INVERTED SURFACE TROUGH WASHES OUT TODAY AND THE NEXT SYSTEM TRACKS THROUGH THE OZARKS...THE SURFACE RIDGE AXIS WILL LIFT NORTH OF THE REGION AND SHOULD KEEP ANY OF THE POTENTIAL FOG THERE AS WELL. THE DRY LOW LEVEL AIR IN PLACE FROM THE RIDGE IS ONE OF THE CONCERNS GOING INTO THE NEXT SYSTEM ON TUESDAY AND HOW FAST THE COLUMN WILL BE ABLE TO SATURATE OUT. CONFIDENCE REMAINS SOMEWHAT LOW IN HOW THE SYSTEM ON TUESDAY WILL PAN OUT...BUT THE TREND STILL APPEARS TO BE FOR A SOUTHERN TRACK THAT MAY KEEP MUCH OF THE FORECAST AREA ON THE DRY SIDE. THE 25.00Z NAM IS A CONSIDERABLE OUTLIER WITH ITS TRACK TO THE NORTH AND HAS BEEN CORRECTED WITH THE 25.06Z RUN. 25.00Z GFS/25.06Z NAM BUFKIT SOUNDINGS SHOW A DRY LAYER BETWEEN 900MB AND 700MB THAT WILL TAKE SOME TIME TO SATURATE OUT AS THE SYSTEM APPROACHES FROM THE SOUTHWEST. HAVE REALLY SLOWED DOWN THE TIMING OF THE SNOW MOVING IN ON TUESDAY FROM THE SOUTH AS THE DRY AIR APPEARS TO WIN OUT FOR MUCH OF THE DAY. THROUGH 00Z WEDNESDAY...THE BEST CHANCES FOR ANY SNOW APPEAR TO BE IN CLAYTON/GRANT COUNTIES...THOUGH THE ONLY 25.00Z MODEL THAT HAS ANY SNOW IN THERE BY THAT TIME IS THE GFS WHICH IS NOTORIOUSLY HIGH ON ITS HUMIDITY AT TIMES. THUS...MORE ADJUSTMENTS MAY BE NEEDED IN FORECAST AS CONFIDENCE INCREASES THAT THE SNOW WILL NOT OCCUR. THIS 12Z TUESDAY THROUGH 00Z WEDNESDAY PERIOD IS CRUCIAL BECAUSE IT IS GOING TO BE THE MAIN TIME FRAME FOR ANY DECENT SNOWFALL ACCUMULATION. AFTER 00Z WEDNESDAY...THE SYSTEM LOSES A LOT OF ITS DEEP/STRONG FORCING AS THE LOW FILLS INTO THE NIGHT. FOR NOW...HAVE MAINTAINED SOME 2-4 INCH SNOW AMOUNTS FOR CLAYTON/GRANT COUNTY WITH LESS THAN 2 INCHES NORTHWEST OF THERE TUESDAY INTO TUESDAY NIGHT...BUT AS MENTIONED...CONFIDENCE IN THIS OCCURRING IS FAIRLY LOW AND BASED ON THIS WOULD NOT THINK THAT AN ADVISORY IS GOING TO BE NEEDED. HOW LONG THE LIGHT SNOW MAY LINGER IS ALSO IN QUESTION AS 25.00Z GFS/25.06Z NAM BUFKIT SOUNDINGS SHOW WEAK LIFT AND DIMINISHING SATURATION OF THE COLUMN INTO WEDNESDAY NIGHT. MAINTAINED SOME CHANCES OF SOME LIGHT SNOW WITH THE HIGHEST CHANCES ACROSS SOUTHWEST WISCONSIN AND NORTHEAST IOWA WHERE THE CORE OF THE UPPER LEVEL LOW WILL TRACK ACROSS. ANY SNOW AMOUNTS OVER THIS PERIOD WOULD BE LIGHT AT LESS THAN AN INCH. .LONG TERM...THURSDAY THROUGH SUNDAY 320 AM CST MON FEB 25 2013 AFTER THE SYSTEM MOVES OFF TO THE EAST COAST BY MID WEEK...A BROAD RIDGE OF HIGH PRESSURE WILL EXTEND DOWN FROM NORTH CENTRAL CANADA DOWN TO THE GULF COAST AND REMAIN ACROSS THE UPPER MISSISSIPPI RIVER VALLEY REGION INTO NEXT WEEKEND. WHILE THE LOW TO UPPER LEVEL FLOW WILL BE OUT OF THE NORTH...THERE IS NOT MUCH OF A COLD SOURCE TO PULL FROM OUT OF CENTRAL CANADA...SO TEMPERATURES SHOULD NOT TAKE MUCH OF A HIT THROUGH THE WEEK. CLEARING SKIES AND AN INCREASING SUN ANGLE WILL HELP AS WELL TO KEEP TEMPERATURES NEAR NORMAL. && .AVIATION...THROUGH 06Z TUESDAY 1149 PM CST SUN FEB 24 2013 CLOUDS ARE NOW FIRMLY ENTRENCHED AT THE TAF SITES. A THICK UPPER CLOUD HAS ALSO FORMED ABOVE THE LOWEST CEILING LAYER...WHICH WILL PREVENT IFR FOG FROM FORMING THROUGH MORNING. HOWEVER...SOME MVFR BR AND LOWER MVFR CIGS ARE EXPECTED TO FORM AS A BAND OF LIFT ACROSS KRST BEGINS TO CAUSE SOME -SHSN AND BETTER SATURATION IN THE BOUNDARY LAYER. CURRENT THINKING ON THE -SNSH IS THAT IT WILL BE SPOTTY NEAR KRST UNTIL THE NEAR-DAWN HOURS MONDAY WHEN A LIGHT SNOW PERIOD IS POSSIBLE. THIS MAY CAUSE PERIODIC IFR SHOULD THE LIFT BE STRONG ENOUGH TO SATURATE THE LOW-LEVELS. KLSE MAY SEE A FEW -SHSN BUT CONFIDENCE WAS NOT HIGH ENOUGH TO INCLUDE IN THE TAF. THIS LIFT WILL PASS OF TO THE NORTHEAST BY LATER MORNING ENDING THE SHSN ACTIVITY...WITH IMPROVING CONDITIONS TO VFR. && .ARX WATCHES/WARNINGS/ADVISORIES... 320 AM CST MON FEB 25 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM...HALBACH AVIATION...BAUMGARDT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1150 PM CST SUN FEB 24 2013 .SHORT TERM... 1008 PM CST SUN FEB 24 2013 TOUGH LITTLE FORECAST TONIGHT WITH DETAILS IN A MESSY PATTERN. WAS WORKING TO TRY AND FIGURE OUT THE FORECAST OF THE BAND OF WEAK ECHO FROM ROUGHLY OMAHA TO ROCHESTER MN AND ITS IMPACT LATE TONIGHT. BIGGEST CONCERN IS A BIT OF LIGHT ACCUMULATING SNOW AROUND COMMUTE TIME. TWO LEVELS OF CLOUDS ARE SLOWLY WORKING INTO THE AREA FROM THE SOUTHWEST. WEST OF THE MISS RIVER A LOWER LEVEL CLOUD DECK IS KEEPING TEMPERATURES WARMER THAN FORECAST AND HAVE ADJUSTED THESE AND WITH MORE CLOUD OVERNIGHT...HAVE RAISED OVERNIGHT LOWS BY A2-3F THERE. CLEARING IN CENTRAL WI WILL CONTINUE TO PROMOTE COOLING AND FOG IN THE RIDGE AXIS. WITH CLOUDS COMING IN THOUGH...ANY DENSE FOG SHOULD BE SHORT LIVED SO CONTINUED THE TREND OF NO FOG AFTER 09Z SOUTH OF I-94. FRONTOGENETIC BAND BETWEEN NORTHERN SYSTEM AND SOUTHERN SYSTEM IS CAUSING ENOUGH LIFT FOR THE ECHO BAND MENTIONED ABOVE FROM OMAHA NORTHEAST. GUIDANCE HAVE MIXED REVIEWS ON THIS BAND BUT OVERALL IT SHOULD INTENSIFY OVER IOWA AND SHIFT NORTHEAST OVERNIGHT. NEW 25.00Z NAM HAS ABOUT 0.5 INCHES ACROSS SERN MN/NERN IA BY MID- MORNING. 24.18Z GFS AND RAP ALSO SHOW MEASURABLE SNOW. SO...HAVE TAKEN A STEP TOWARD LIGHT SNOW MOVING IN BY SUNRISE. THEN...THE SNOWS SHIFT NORTHEAST AND THE FORCING DOES WEAKEN. THEREFORE...HAVE LEFT FLURRIES IN THE MORNING OVER THE NORTHWEST FORECAST AREA. THE RAOB AT KMPX AT 00Z IS QUITE DRY...BUT IT IS MORE MOIST FURTHER SOUTH. SYSTEM TO THE SOUTH WILL BE VERY CLOSE WITH THE NEW 25.00Z NAM COMING IN WITH HIGHER AMOUNTS. THE FAR SOUTH /GRANT AND FAYETTE COUNTIES/ ARE VERY CLOSE TO A WATCH WITH SOME HIGHER WIND GUSTS ALSO INVOLVED. WITH THE 24.18Z GFS SUGGESTING 8 INCHES AS THE HIGH OUTLIER AS OF LATE. WILL NOT MAKE CHANGES NOW...BUT A HIGH END ADVISORY IS A SURE BET IT APPEARS. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY 306 PM CST SUN FEB 24 2013 THE LONG TERM FORECAST CONTINUES TO LOOK QUIET. GOOD MODEL AGREEMENT CONTINUES AMONGST THE 24.12Z ECMWF/GFS/CANADIAN AND ECMWF ENSEMBLES...WHICH SHOW RIDGING BUILDING UP OVER THE WESTERN U.S. THROUGH SATURDAY WHILE TROUGHING HANGS IN PLACE OVER THE EASTERN U.S.. THE FORECAST AREA IS CAUGHT IN THE MIDDLE BETWEEN THE TWO...FAVORING A RIDGE OF HIGH PRESSURE WHICH SLOWLY BUILDS EAST INTO THE FORECAST AREA DURING THIS PERIOD. THERE ARE INDICATIONS OF A SHORTWAVE TROUGH DROPPING SOUTH THROUGH THE AREA ON FRIDAY...BUT THERE ARE BOTH UNCERTAINTIES EXACTLY ON WHERE IT TRACKS AND WHETHER IT WILL HAVE ENOUGH MOISTURE TO PRODUCE PRECIPITATION. THEREFORE... AFTER SOME LINGERING SMALL PRECIPITATION CHANCES OVER WISCONSIN AREAS WEDNESDAY NIGHT ASSOCIATED WITH THE SLOWLY DEPARTING AND WEAKENING STORM TO OUR EAST...HAVE A DRY FORECAST FOR THURSDAY INTO SATURDAY. HEADING INTO SUNDAY...A MORE POTENT SHORTWAVE TROUGH LOOKS TO CRASH THROUGH THE WESTERN U.S. RIDGE...BUT ONLY MAKE IT INTO THE NORTHERN ROCKIES BY 00Z MONDAY. IT SHOULD BE ENOUGH TO PUSH SOME OF THE UPPER RIDGE EAST...ALLOWING THE SURFACE HIGH PRESSURE RIDGE TO AT LEAST MOVE OVER IF NOT SHIFT OFF TO THE EAST FORECAST AREA. NEEDLESS TO SAY...ANOTHER DRY DAY IS ANTICIPATED SUNDAY. TEMPERATURES ARE A LITTLE TOUGH GIVEN A NORTHERLY FLOW PRESENT WHICH BRINGS DOWN SOME COOLER AIR FOR MUCH OF THE PERIOD. HOWEVER...IT IS NOT THAT COLD...NOTED BY 850MB TEMPS AT MOST DROPPING TO -8 TO -12C BY FRIDAY. ANY SUNSHINE THAT OCCURS...WHICH MORE COULD HAPPEN IF THE ECMWF IS RIGHT...WILL ALLOW FOR GOOD MIXING. THUS HAVE LEFT A CONSENSUS APPROACH WHICH YIELDS HIGHS JUST SLIGHTLY BELOW NORMAL. && .AVIATION...THROUGH 06Z TUESDAY 1149 PM CST SUN FEB 24 2013 CLOUDS ARE NOW FIRMLY ENTRENCHED AT THE TAF SITES. A THICK UPPER CLOUD HAS ALSO FORMED ABOVE THE LOWEST CEILING LAYER...WHICH WILL PREVENT IFR FOG FROM FORMING THROUGH MORNING. HOWEVER...SOME MVFR BR AND LOWER MVFR CIGS ARE EXPECTED TO FORM AS A BAND OF LIFT ACROSS KRST BEGINS TO CAUSE SOME -SHSN AND BETTER SATURATION IN THE BOUNDARY LAYER. CURRENT THINKING ON THE -SNSH IS THAT IT WILL BE SPOTTY NEAR KRST UNTIL THE NEAR-DAWN HOURS MONDAY WHEN A LIGHT SNOW PERIOD IS POSSIBLE. THIS MAY CAUSE PERIODIC IFR SHOULD THE LIFT BE STRONG ENOUGH TO SATURATE THE LOW-LEVELS. KLSE MAY SEE A FEW -SHSN BUT CONFIDENCE WAS NOT HIGH ENOUGH TO INCLUDE IN THE TAF. THIS LIFT WILL PASS OF TO THE NORTHEAST BY LATER MORNING ENDING THE SHSN ACTIVITY...WITH IMPROVING CONDITIONS TO VFR. && .ARX WATCHES/WARNINGS/ADVISORIES... 306 PM CST SUN FEB 24 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BAUMGARDT LONG TERM...AJ AVIATION...BAUMGARDT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1008 PM CST SUN FEB 24 2013 .SHORT TERM... 1008 PM CST SUN FEB 24 2013 TOUGH LITTLE FORECAST TONIGHT WITH DETAILS IN A MESSY PATTERN. WAS WORKING TO TRY AND FIGURE OUT THE FORECAST OF THE BAND OF WEAK ECHO FROM ROUGHLY OMAHA TO ROCHESTER MN AND ITS IMPACT LATE TONIGHT. BIGGEST CONCERN IS A BIT OF LIGHT ACCUMULATING SNOW AROUND COMMUTE TIME. TWO LEVELS OF CLOUDS ARE SLOWLY WORKING INTO THE AREA FROM THE SOUTHWEST. WEST OF THE MISS RIVER A LOWER LEVEL CLOUD DECK IS KEEPING TEMPERATURES WARMER THAN FORECAST AND HAVE ADJUSTED THESE AND WITH MORE CLOUD OVERNIGHT...HAVE RAISED OVERNIGHT LOWS BY A2-3F THERE. CLEARING IN CENTRAL WI WILL CONTINUE TO PROMOTE COOLING AND FOG IN THE RIDGE AXIS. WITH CLOUDS COMING IN THOUGH...ANY DENSE FOG SHOULD BE SHORT LIVED SO CONTINUED THE TREND OF NO FOG AFTER 09Z SOUTH OF I-94. FRONTOGENETIC BAND BETWEEN NORTHERN SYSTEM AND SOUTHERN SYSTEM IS CAUSING ENOUGH LIFT FOR THE ECHO BAND MENTIONED ABOVE FROM OMAHA NORTHEAST. GUIDANCE HAVE MIXED REVIEWS ON THIS BAND BUT OVERALL IT SHOULD INTENSIFY OVER IOWA AND SHIFT NORTHEAST OVERNIGHT. NEW 25.00Z NAM HAS ABOUT 0.5 INCHES ACROSS SERN MN/NERN IA BY MID- MORNING. 24.18Z GFS AND RAP ALSO SHOW MEASURABLE SNOW. SO...HAVE TAKEN A STEP TOWARD LIGHT SNOW MOVING IN BY SUNRISE. THEN...THE SNOWS SHIFT NORTHEAST AND THE FORCING DOES WEAKEN. THEREFORE...HAVE LEFT FLURRIES IN THE MORNING OVER THE NORTHWEST FORECAST AREA. THE RAOB AT KMPX AT 00Z IS QUITE DRY...BUT IT IS MORE MOSIT FURTHER SOUTH. SYSTEM TO THE SOUTH WILL BE VERY CLOSE WITH THE NEW 25.00Z NAM COMING IN WITH HIGHER AMOUNTS. THE FAR SOUTH /GRANT AND FAYETTE COUNTIES/ ARE VERY CLOSE TO A WATCH WITH SOME HIGHER WIND GUSTS ALSO INVOLVED. WITH THE 24.18Z GFS SUGGESTING 8 INCHES AS THE HIGH OUTLIER AS OF LATE. WILL NOT MAKE CHANGES NOW...BUT A HIGH END ADVISORY IS A SURE BET IT APPEARS. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY 306 PM CST SUN FEB 24 2013 THE LONG TERM FORECAST CONTINUES TO LOOK QUIET. GOOD MODEL AGREEMENT CONTINUES AMONGST THE 24.12Z ECMWF/GFS/CANADIAN AND ECMWF ENSEMBLES...WHICH SHOW RIDGING BUILDING UP OVER THE WESTERN U.S. THROUGH SATURDAY WHILE TROUGHING HANGS IN PLACE OVER THE EASTERN U.S.. THE FORECAST AREA IS CAUGHT IN THE MIDDLE BETWEEN THE TWO...FAVORING A RIDGE OF HIGH PRESSURE WHICH SLOWLY BUILDS EAST INTO THE FORECAST AREA DURING THIS PERIOD. THERE ARE INDICATIONS OF A SHORTWAVE TROUGH DROPPING SOUTH THROUGH THE AREA ON FRIDAY...BUT THERE ARE BOTH UNCERTAINTIES EXACTLY ON WHERE IT TRACKS AND WHETHER IT WILL HAVE ENOUGH MOISTURE TO PRODUCE PRECIPITATION. THEREFORE... AFTER SOME LINGERING SMALL PRECIPITATION CHANCES OVER WISCONSIN AREAS WEDNESDAY NIGHT ASSOCIATED WITH THE SLOWLY DEPARTING AND WEAKENING STORM TO OUR EAST...HAVE A DRY FORECAST FOR THURSDAY INTO SATURDAY. HEADING INTO SUNDAY...A MORE POTENT SHORTWAVE TROUGH LOOKS TO CRASH THROUGH THE WESTERN U.S. RIDGE...BUT ONLY MAKE IT INTO THE NORTHERN ROCKIES BY 00Z MONDAY. IT SHOULD BE ENOUGH TO PUSH SOME OF THE UPPER RIDGE EAST...ALLOWING THE SURFACE HIGH PRESSURE RIDGE TO AT LEAST MOVE OVER IF NOT SHIFT OFF TO THE EAST FORECAST AREA. NEEDLESS TO SAY...ANOTHER DRY DAY IS ANTICIPATED SUNDAY. TEMPERATURES ARE A LITTLE TOUGH GIVEN A NORTHERLY FLOW PRESENT WHICH BRINGS DOWN SOME COOLER AIR FOR MUCH OF THE PERIOD. HOWEVER...IT IS NOT THAT COLD...NOTED BY 850MB TEMPS AT MOST DROPPING TO -8 TO -12C BY FRIDAY. ANY SUNSHINE THAT OCCURS...WHICH MORE COULD HAPPEN IF THE ECMWF IS RIGHT...WILL ALLOW FOR GOOD MIXING. THUS HAVE LEFT A CONSENSUS APPROACH WHICH YIELDS HIGHS JUST SLIGHTLY BELOW NORMAL. && .AVIATION...TONIGHT AND TUESDAY 626 PM CST SUN FEB 24 2013 A CHALLENGING CLOUD AND FOG FORECAST OVERNIGHT INTO MONDAY. AT 00Z...A NORTHEAST-SOUTHWEST ORIENTED MVFR STRATUS DECK IS LOCATED FROM SERN MN TO OMAHA NEBRASKA. KRST NOW IS IN THIS STRATUS... WHICH IS SPREADING SLOWLY NORTHEAST. THIS WILL WORK INTO KLSE SHORTLY. SOME HIGHER CLOUD OVER THE TOP OF THE MVFR STRATUS IS ALSO SPREADING NORTHEAST FROM THE BIGGER STORM SYSTEM OVER THE SOUTHERN PLAINS. WITH LIGHT WINDS AND SURFACE RIDGING IN PLACE AND LIGHT WINDS...AS OVERNIGHT TEMPERATURES COOL...THE STRATUS IS EXPECTED TO SLOWLY LOWER AS THE BOUNDARY LAYER SATURATES. AT THIS TIME THE NEW TAFS HAVE SLOWED THE DETERIORATION TO IFR AT KRST TO AFTER 06Z. BUT HAVE ALSO LOWERED THE VSBYS TO 1 MILE BY MORNING...AND IT COULD BE LIFR CIG/VSBY SHOULD THE CONDITIONS COME TOGETHER RIGHT AND THE SECOND LAYER OF CLOUD ABOVE THE STRATUS IS MINIMAL. THOSE WITH FLYING INTERESTS IN THE MORNING SHOULD AT LEAST PLAN ON LOWER MVFR...POSSIBLY DOWN TO LIFR. && .ARX WATCHES/WARNINGS/ADVISORIES... 306 PM CST SUN FEB 24 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BAUMGARDT LONG TERM...AJ AVIATION...BAUMGARDT
AREA FORECAST DISCUSSION
NWS PUEBLO CO
150 AM MST WED FEB 27 2013 .UPDATE... ISSUED AT 141 AM MST WED FEB 27 2013 ALTHOUGH STARTING TO TREND DOWNWARD...SNOW AND BLOWING SNOW CONTINUES OVER THE PALMER DIVIDE. EXTENDED WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW FOR THE DIVIDE THROUGH 5 AM. UPDATED SHORT TERM FORECASTS TO REFLECT CURRENT OBSERVATIONS AND TRENDS. LW UPDATE ISSUED AT 1022 PM MST TUE FEB 26 2013 SNOW GRADUALLY WINDING DOWN OVER NORTHERN EL PASO COUNTY...THOUGH STILL A COUPLE MORE NARROW BANDS OF AT LEAST BRIEFLY MODERATE SNOW POSSIBLE OVER EXTREME NERN PART OF THE COUNTY AS AREA OF HIGHER REFLECTIVITY EAST OF DENVER METRO ROTATES SOUTH. EXPECT ANY ADDITIONAL ACCUMULATIONS TO BE GENERALLY AN INCH OR LESS. WINDS STILL GUSTING 25-35 KNOTS FROM KFLY AND KMNH EAST TO KLIC...AND LATEST HRRR KEEPS GUSTS IN THE 25-30 KT RANGE UNTIL AROUND 09Z- 10Z. WILL KEEP ADVISORY IN PLACE UNTIL 09Z...AS LOCAL MEDIA/ROAD REPORTS CONTINUE TO INDICATE VERY DIFFICULT TRAVEL EAST/NORTHEAST OF COLORADO SPRINGS DUE TO LOW VIS AND DRIFTING SNOW. ELSEWHERE...LIGHT SNOW WILL CONTINUE A FEW MORE HOURS MAINLY SOUTH OF THE ARKANSAS RIVER AND OVER THE WETS/SANGRES...THOUGH ADDITIONAL ACCUMS HERE LOOK LIGHT...LESS THAN AN INCH. UPDATE ISSUED AT 740 PM MST TUE FEB 26 2013 ISSUED A SHORT FUSED WINTER WEATHER ADVISORY FOR NORTHERN EL PASO COUNTY...AS WINDS HAVE INCREASED AND BANDS OF MODERATE TO HEAVY SNOW CONTINUE TO ROTATE SOUTH. LATEST HRRR KEEPS PRECIP GOING UNTIL 08Z...AND SHOWS WIND GUSTS OVER 30 KTS NEAR THE PALMER DIVIDE UNTIL AT LEAST 10Z. HAVE HAD NUMEROUS REPORTS OF ROAD CLOSURES/DIFFICULT TRAVEL DUE TO WIDESPREAD BLOWING/DRIFTING SNOW NORTH AND EAST OF COS. FORECASTS FOR THE REMAINDER OF THE AREA WERE REFRESHED TO ACCOUNT FOR ONGOING PRECIP. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 325 PM MST TUE FEB 26 2013 SHORT TERM METEOROLOGICAL ISSUES INCLUDE BUT ARE NOT LIMITED TO POPS/SNOW AMOUNTS...WINDS AND TEMPERATURES. FORECAST DISTRICT CURRENTLY NOTING SNOW ACTIVITY...ESPECIALLY OVER THE MOUNTAINS AND HIGHER TERRAIN AREAS AS WELL AS OVER MANY PORTIONS OF THE I-25 CORRIDOR AS WELL AS AREAS OF GUSTY NORTH WINDS. AS OF 3 PM MST...REPORTED SNOW AMOUNTS HAVE GENERALLY BEEN UNDER 4 INCHES...I.E RECENTLY RECEIVED A SPOTTER SNOW REPORT OF 3.5 INCHES OF SNOW 11 MILES TO THE NORTH-NORTHEAST OF CRESTONE IN CUSTER COUNTY(PUBLIC ZONE 72) WITH LIGHT SNOW CONTINUING. LATEST SHORT/NEAR-TERM COMPUTER SIMULATIONS...FORECAST MODEL SOUNDINGS AND REAL-TIME DATA INDICATE THAT THE UPPER DISTURBANCE WILL CONTINUE TO IMPACT MANY SECTIONS OF THE CWFA INTO TONIGHT BEFORE SHIFTING EAST OF THE FORECAST DISTRICT BY WEDNESDAY MORNING. STILL EXPECT THAT 4 TO 8 INCH SNOW TOTALS(INCLUDING SNOW THAT HAS ALREADY FALLEN EARLIER TODAY...I.E. 12 TO 18 HOUR TIME-RANGE) WILL BE POSSIBLE OVER MANY MOUNTAIN AND HIGHER FOOTHILL LOCATIONS WITH 2 TO 5 INCHES OF SNOW OVER NORTHERN EL PASO COUNTY AND 2 INCHES OR LESS OF SNOW ELSEWHERE WILL BE NOTED BEFORE THIS EVENT ENDS LATER TONIGHT. IN ADDITION...A FEW LOCALLY HIGHER SNOW AMOUNTS WILL ALSO BE POSSIBLE BY SUNRISE WEDNESDAY. IN ADDITION TO THE SNOW FROM THIS AFTERNOON INTO TONIGHT...GUSTY NORTH WINDS AT TIMES ARE ALSO EXPECTED IN COMBINATION WITH CONTINUED BELOW SEASONAL LATE FEBRUARY TEMPERATURES. FOR WEDNESDAY...AS UPPER SYSTEM DEPARTS SOUTHERN COLORADO...ANTICIPATE THAT GENERALLY DRY CONDITIONS IN COMBINATION WITH CLEARING SKIES...DECREASING WINDS(EXCEPT FOR POSSIBLY FAR EASTERN SECTIONS) AND WARMER TEMPERATURES(ALTHOUGH STILL BELOW LATE FEBRUARY CLIMATOLOGICAL AVERAGES) WILL BE NOTED ACROSS THE FORECAST DISTRICT. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 325 PM MST TUE FEB 26 2013 WED NIGHT...GENERALLY DRY NW FLOW ALOFT WL BE OVR THE AREA...BUT THERE COULD BE A FEW SHOWERS OVR THE CONTDVD MAINLY IN THE EVENING HOURS. FORECAST MODELS DO NOT AGREE ON THE WEATHER FOR LATE THU AND THU NIGHT. THE GFS HAS THE AREA MOSTLY DRY INTO THE EARLY AFTERNOON...BUT LATE IN THE AFTERNOON A SHORTWAVE TROF DROPS INTO SWRN WY AND AHEAD OF THIS SYSTEM...WITH MOISTURE INCREASING AND THE GFS BRINGS CHANCES FOR SNOW TO THE CENTRAL MTS AND TO THE PIKES PEAK TELLER COUNTY REGION. THEN THU NIGHT THAT SYSTEM DROP SOUTH THU CO...SPREADING PCPN CHANCES SOUTHWARD AS WELL. THE NAM AND THE ECMWF DO NOT HAVE THIS SHORTWAVE TROF AND IS KEEPING THE WEATHER DRY. WL STICK WITH SOME PCPN IN THE CENTRAL MTS...WITH MAYBE JUST A FEW SHOWERS OVR THE OTHER MTN PEAKS AND SEE WHAT FUTURE MODEL RUNS BRING. FRI...AS AN UPR LOW DROPS INTO WRN MO AND ERN KS A FRONT BRING SOME BREEZY NORTHERLY WINDS TO MUCH OF THE EASTERN CO PLAINS. THE NAM IS MOSTLY DRY OVR THE AREA FOR FRI...WHILE THE GFS AND ECMWF BOTH SHOW SOME POTENTIAL FOR PCPN OVR THE MTS AND ERN PLAINS. AN UPR RIDGE THEN BUILD OVR THE AREA FOR THE WEEKEND...RESULTING IN DRY WEATHER AND WARMER TEMPS. LATE SUN THE UPR RIDGE GETS FLATTENED OVR THE AREA AS A NEW UPR LOW MOVES INTO WRN MT. THE TRACK OF THAT UPR LOW IS THEN QUITE UNCERTAIN AS THE GFS BRINGS IT SOUTHEASTWARD AND ACRS NORTHEAST CO BY MIDDAY MON WHILE THE ECMWF STILL HAS IT OVR MT. BY 06Z TUE THE GFS MOVES THE LOW INTO NRN MO...WHILE THE ECMWF HAS IT OVR SRN MT AND NRN WY. THUS ITS HARD TO SAY EXACTLY WHAT IS IN STORE FOR THE FORECAST AREA SUN NIGHT AND MON BUT FOR NOW BOTH MODELS AT LEAST HAVE SOME PCPN OVR THE CENTRAL MTS. WL PROBABLY SEE A SHORTWAVE RIDGE AND MAINLY DRY WEATHER OVR THE AREA ON TUE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1022 PM MST TUE FEB 26 2013 AT KCOS...STILL A FEW LIGHT -SHSN IN THE AREA AS OF 0530Z...THOUGH INTENSITY HAS BEEN DECREASING THE LAST COUPLE HOURS. WILL CARRY -SN IN THE TAF UNTIL AROUND 08Z...ALONG WITH OCCASIONAL MVFR VIS IN BLOWING SNOW AS GUSTY NORTH WINDS PERSIST. VFR CONDITIONS THEN EXPECTED FROM EARLY MORNING THROUGH THE DAY WEDNESDAY AS UPPER SYSTEM PULLS AWAY. NORTH WINDS WILL DIMINISH THROUGH THE MORNING...GRADUALLY TURNING TO THE SOUTH BY AFTERNOON. AT KPUB AND KALS...KEPT A MENTION OF VCSH UNTIL 08Z...THOUGH ANY -SHSN WILL BE VERY BRIEF AND HAVE LITTLE IMPACT. NORTH WINDS WILL REMAIN GUSTY UNTIL 10-12Z...THEN DIMINISH. ON TUES...EXPECT VFR CONDITONS WITH MUCH LIGHTER WINDS. MOUNTAINS AND PALMER DIVIDE WILL CONTINUE TO BE OBSCURRED BY LOW CLOUDS AND -SHSN THROUGH THE NIGHT...THEN SNOW ENDS AND SKIES GRADUALLY CLEAR AROUND SUNRISE. OVER THE PLAINS...ISOLATED MVFR CIGS/VIS IN -SHSN WILL COME TO AND END 08Z-10Z WITH VFR MOST AREAS BY 12Z. && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 5 AM MST EARLY THIS MORNING FOR COZ084. && $$ UPDATE...LW SHORT TERM...77 LONG TERM...28 AVIATION...PETERSEN
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1039 PM MST TUE FEB 26 2013 .UPDATE... ISSUED AT 1022 PM MST TUE FEB 26 2013 SNOW GRADUALLY WINDING DOWN OVER NORTHERN EL PASO COUNTY...THOUGH STILL A COUPLE MORE NARROW BANDS OF AT LEAST BRIEFLY MODERATE SNOW POSSIBLE OVER EXTREME NERN PART OF THE COUNTY AS AREA OF HIGHER REFLECTIVITY EAST OF DENVER METRO ROTATES SOUTH. EXPECT ANY ADDITIONAL ACCUMULATIONS TO BE GENERALLY AN INCH OR LESS. WINDS STILL GUSTING 25-35 KNOTS FROM KFLY AND KMNH EAST TO KLIC...AND LATEST HRRR KEEPS GUSTS IN THE 25-30 KT RANGE UNTIL AROUND 09Z- 10Z. WILL KEEP ADVISORY IN PLACE UNTIL 09Z...AS LOCAL MEDIA/ROAD REPORTS CONTINUE TO INDICATE VERY DIFFICULT TRAVEL EAST/NORTHEAST OF COLORADO SPRINGS DUE TO LOW VIS AND DRIFTING SNOW. ELSEWHERE...LIGHT SNOW WILL CONTINUE A FEW MORE HOURS MAINLY SOUTH OF THE ARKANSAS RIVER AND OVER THE WETS/SANGRES...THOUGH ADDITIONAL ACCUMS HERE LOOK LIGHT...LESS THAN AN INCH. UPDATE ISSUED AT 740 PM MST TUE FEB 26 2013 ISSUED A SHORT FUSED WINTER WEATHER ADVISORY FOR NORTHERN EL PASO COUNTY...AS WINDS HAVE INCREASED AND BANDS OF MODERATE TO HEAVY SNOW CONTINUE TO ROTATE SOUTH. LATEST HRRR KEEPS PRECIP GOING UNTIL 08Z...AND SHOWS WIND GUSTS OVER 30 KTS NEAR THE PALMER DIVIDE UNTIL AT LEAST 10Z. HAVE HAD NUMEROUS REPORTS OF ROAD CLOSURES/DIFFICULT TRAVEL DUE TO WIDESPREAD BLOWING/DRIFTING SNOW NORTH AND EAST OF COS. FORECASTS FOR THE REMAINDER OF THE AREA WERE REFRESHED TO ACCOUNT FOR ONGOING PRECIP. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 325 PM MST TUE FEB 26 2013 SHORT TERM METEOROLOGICAL ISSUES INCLUDE BUT ARE NOT LIMITED TO POPS/SNOW AMOUNTS...WINDS AND TEMPERATURES. FORECAST DISTRICT CURRENTLY NOTING SNOW ACTIVITY...ESPECIALLY OVER THE MOUNTAINS AND HIGHER TERRAIN AREAS AS WELL AS OVER MANY PORTIONS OF THE I-25 CORRIDOR AS WELL AS AREAS OF GUSTY NORTH WINDS. AS OF 3 PM MST...REPORTED SNOW AMOUNTS HAVE GENERALLY BEEN UNDER 4 INCHES...I.E RECENTLY RECEIVED A SPOTTER SNOW REPORT OF 3.5 INCHES OF SNOW 11 MILES TO THE NORTH-NORTHEAST OF CRESTONE IN CUSTER COUNTY(PUBLIC ZONE 72) WITH LIGHT SNOW CONTINUING. LATEST SHORT/NEAR-TERM COMPUTER SIMULATIONS...FORECAST MODEL SOUNDINGS AND REAL-TIME DATA INDICATE THAT THE UPPER DISTURBANCE WILL CONTINUE TO IMPACT MANY SECTIONS OF THE CWFA INTO TONIGHT BEFORE SHIFTING EAST OF THE FORECAST DISTRICT BY WEDNESDAY MORNING. STILL EXPECT THAT 4 TO 8 INCH SNOW TOTALS(INCLUDING SNOW THAT HAS ALREADY FALLEN EARLIER TODAY...I.E. 12 TO 18 HOUR TIME-RANGE) WILL BE POSSIBLE OVER MANY MOUNTAIN AND HIGHER FOOTHILL LOCATIONS WITH 2 TO 5 INCHES OF SNOW OVER NORTHERN EL PASO COUNTY AND 2 INCHES OR LESS OF SNOW ELSEWHERE WILL BE NOTED BEFORE THIS EVENT ENDS LATER TONIGHT. IN ADDITION...A FEW LOCALLY HIGHER SNOW AMOUNTS WILL ALSO BE POSSIBLE BY SUNRISE WEDNESDAY. IN ADDITION TO THE SNOW FROM THIS AFTERNOON INTO TONIGHT...GUSTY NORTH WINDS AT TIMES ARE ALSO EXPECTED IN COMBINATION WITH CONTINUED BELOW SEASONAL LATE FEBRUARY TEMPERATURES. FOR WEDNESDAY...AS UPPER SYSTEM DEPARTS SOUTHERN COLORADO...ANTICIPATE THAT GENERALLY DRY CONDITIONS IN COMBINATION WITH CLEARING SKIES...DECREASING WINDS(EXCEPT FOR POSSIBLY FAR EASTERN SECTIONS) AND WARMER TEMPERATURES(ALTHOUGH STILL BELOW LATE FEBRUARY CLIMATOLOGICAL AVERAGES) WILL BE NOTED ACROSS THE FORECAST DISTRICT. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 325 PM MST TUE FEB 26 2013 WED NIGHT...GENERALLY DRY NW FLOW ALOFT WL BE OVR THE AREA...BUT THERE COULD BE A FEW SHOWERS OVR THE CONTDVD MAINLY IN THE EVENING HOURS. FORECAST MODELS DO NOT AGREE ON THE WEATHER FOR LATE THU AND THU NIGHT. THE GFS HAS THE AREA MOSTLY DRY INTO THE EARLY AFTERNOON...BUT LATE IN THE AFTERNOON A SHORTWAVE TROF DROPS INTO SWRN WY AND AHEAD OF THIS SYSTEM...WITH MOISTURE INCREASING AND THE GFS BRINGS CHANCES FOR SNOW TO THE CENTRAL MTS AND TO THE PIKES PEAK TELLER COUNTY REGION. THEN THU NIGHT THAT SYSTEM DROP SOUTH THU CO...SPREADING PCPN CHANCES SOUTHWARD AS WELL. THE NAM AND THE ECMWF DO NOT HAVE THIS SHORTWAVE TROF AND IS KEEPING THE WEATHER DRY. WL STICK WITH SOME PCPN IN THE CENTRAL MTS...WITH MAYBE JUST A FEW SHOWERS OVR THE OTHER MTN PEAKS AND SEE WHAT FUTURE MODEL RUNS BRING. FRI...AS AN UPR LOW DROPS INTO WRN MO AND ERN KS A FRONT BRING SOME BREEZY NORTHERLY WINDS TO MUCH OF THE EASTERN CO PLAINS. THE NAM IS MOSTLY DRY OVR THE AREA FOR FRI...WHILE THE GFS AND ECMWF BOTH SHOW SOME POTENTIAL FOR PCPN OVR THE MTS AND ERN PLAINS. AN UPR RIDGE THEN BUILD OVR THE AREA FOR THE WEEKEND...RESULTING IN DRY WEATHER AND WARMER TEMPS. LATE SUN THE UPR RIDGE GETS FLATTENED OVR THE AREA AS A NEW UPR LOW MOVES INTO WRN MT. THE TRACK OF THAT UPR LOW IS THEN QUITE UNCERTAIN AS THE GFS BRINGS IT SOUTHEASTWARD AND ACRS NORTHEAST CO BY MIDDAY MON WHILE THE ECMWF STILL HAS IT OVR MT. BY 06Z TUE THE GFS MOVES THE LOW INTO NRN MO...WHILE THE ECMWF HAS IT OVR SRN MT AND NRN WY. THUS ITS HARD TO SAY EXACTLY WHAT IS IN STORE FOR THE FORECAST AREA SUN NIGHT AND MON BUT FOR NOW BOTH MODELS AT LEAST HAVE SOME PCPN OVR THE CENTRAL MTS. WL PROBABLY SEE A SHORTWAVE RIDGE AND MAINLY DRY WEATHER OVR THE AREA ON TUE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1022 PM MST TUE FEB 26 2013 AT KCOS...STILL A FEW LIGHT -SHSN IN THE AREA AS OF 0530Z...THOUGH INTENSITY HAS BEEN DECREASING THE LAST COUPLE HOURS. WILL CARRY -SN IN THE TAF UNTIL AROUND 08Z...ALONG WITH OCCASIONAL MVFR VIS IN BLOWING SNOW AS GUSTY NORTH WINDS PERSIST. VFR CONDITIONS THEN EXPECTED FROM EARLY MORNING THROUGH THE DAY WEDNESDAY AS UPPER SYSTEM PULLS AWAY. NORTH WINDS WILL DIMINISH THROUGH THE MORNING...GRADUALLY TURNING TO THE SOUTH BY AFTERNOON. AT KPUB AND KALS...KEPT A MENTION OF VCSH UNTIL 08Z...THOUGH ANY -SHSN WILL BE VERY BRIEF AND HAVE LITTLE IMPACT. NORTH WINDS WILL REMAIN GUSTY UNTIL 10-12Z...THEN DIMINISH. ON TUES...EXPECT VFR CONDITONS WITH MUCH LIGHTER WINDS. MOUNTAINS AND PALMER DIVIDE WILL CONTINUE TO BE OBSCURRED BY LOW CLOUDS AND -SHSN THROUGH THE NIGHT...THEN SNOW ENDS AND SKIES GRADUALLY CLEAR AROUND SUNRISE. OVER THE PLAINS...ISOLATED MVFR CIGS/VIS IN -SHSN WILL COME TO AND END 08Z-10Z WITH VFR MOST AREAS BY 12Z. && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 2 AM MST WEDNESDAY FOR COZ084. && $$ UPDATE...MW SHORT TERM...77 LONG TERM...28 AVIATION...PETERSEN
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
359 AM EST WED FEB 27 2013 .DISCUSSION... TODAY-TONIGHT...COOL FRONT NEAR OKEECHOBEE SHOULD ONLY SLIDE A LITTLE MORE TO THE SOUTH AS IT BECOMES NEARLY ALIGNED WITH FLOW ALOFT. THE MODELS ARE SHOWING AN AREA OF RAINFALL BREAKING OUT ACROSS THE SOUTHERN PENINSULA AS MOISTURE OVERRUNS THE BOUNDARY. HOW FAR NORTH THIS OCCURS IS PROBLEMATIC. THE GFS IS QUITE BULLISH WITH 60 POPS IN MARTIN COUNTY AND EVEN 30 PERCENT ALL THE WAY UP TO BREVARD...WHILE THE NAM HAS VALUES ABOUT HALF THAT. WILL SIDE CLOSE TO THE NAM AS CURRENTLY THE ONLY RAINFALL IS OVER FLORIDA BY AND FEEL MOST OF THE PRECIP SHOULD BE FROM LAKE OKEECHOBEE SOUTHWARD. MAX TEMPS WILL BE 5-10 DEGREES COOLER THAN YESTERDAY. DEW POINTS WILL BE NOTICEABLY LOWER ESPECIALLY ACROSS THE NORTH HALF. THE FRONTAL BOUNDARY WILL SLIDE FARTHER SOUTH TONIGHT WHICH WILL ALLOW LOWS TONIGHT TO COOL A LITTLE FURTHER...INTO THE MID-UPPER 40S NORTH AND LOWER 50S SOUTH. THU-FRI...ZONAL FLOW ALOFT EXPECTED OVER THE AREA INTO LATE WEEK WITH DEEP LOW PRESSURE SYSTEM EVENTUALLY MOVING OFFSHORE OF THE NORTHEAST U.S. COAST. LOW LEVEL NORTHWEST FLOW WILL CONTINUE TO TRANSPORT DRIER AND COOLER AIR INTO CENTRAL FLORIDA. HIGHS THURSDAY EXPECTED TO BE IN THE LOW/MID 70S AND THEN IN THE MID/UPPER 60S FRIDAY. LOWS FORECAST TO RANGE FROM THE MID 40S TO LOW 50S THURSDAY NIGHT AND LOW/MID 40S FRIDAY NIGHT. MAY SEE SOME GREATER CLOUD COVER OVER THE AREA FRIDAY AS GFS INDICATES AN INCREASING MID/UPPER LEVEL CLOUD DECK OVER THE REGION ASSOCIATED WITH STRONG 150+ KT JET OVER THE SOUTHEAST UNITED STATES. SAT-SUN...VIGOROUS SHORTWAVE TROUGH WILL DIG SOUTHWARD INTO THE GULF OF MEXICO SATURDAY AND ACROSS FLORIDA SAT NIGHT INTO SUNDAY. LOW LEVEL FLOW WILL REMAIN OUT OF THE W/NW WHICH WILL CONTINUE GRADUAL COOLING INTO THE WEEKEND. TEMPERATURES WILL BE 10 TO 15 DEGREES BELOW NORMAL AND COULD POTENTIALLY SEE LOWS NEAR FREEZING OVER FAR NORTHERN LAKE AND VOLUSIA COUNTIES LATE SUNDAY NIGHT. THE OVERALL AIRMASS WILL REMAIN QUITE DRY WITH PW VALUES AROUND 0.50 INCHES OR LESS. DESPITE THIS THE GFS EXTENDED GUIDANCE KEEPS 20-30 PERCENT POPS OVER THE REGION...DUE TO STRONG TROUGH MOVING THROUGH THE AREA AND INCREASING LOW LEVEL MOISTURE. STILL FEEL THESE POPS ARE TOO HIGH...ESPECIALLY WITH THE GFS AND ECMWF NOT SHOWING ANY QPF OVER EAST CENTRAL FLORIDA. WILL LEAN TOWARD THE ECMWF MOS GUIDANCE AND KEEP A DRY FORECAST OVER THE AREA. MON-TUE...UPPER LEVEL TROUGH PUSHES EAST OF THE AREA INTO EARLY NEXT WEEK WITH HIGH PRESSURE AT THE SURFACE EVENTUALLY BUILDING OVER FLORIDA. BELOW NORMAL TEMPERATURES EXPECTED TO CONTINUE INTO MON/MON NIGHT WITH TEMPERATURES WARMING BACK INTO THE 70S TUESDAY. DRY AIRMASS REMAINS OVER THE AREA...KEEPING RAIN CHANCES OUT OF THE FORECAST. && .AVIATION... SOME MVFR CEILINGS HAVE BEEN OCCURRING EARLY THIS MORNING ESPECIALLY IN THE SOUTH NEAR SLOW MOVING FRONTAL BOUNDARY. DRIER AIR SLOWLY FILTERING IN SHOULD BRING VFR LATER THIS MORNING. MVFR CEILINGS MAY RETURN OVER SOUTHERN AREAS BY AFTERNOON AS MOISTURE OVERRUNS THE FRONTAL BOUNDARY...MAINLY KFPR-KSUA. THERE COULD ALSO BE SOME LIGHT RAIN THERE. && .MARINE... TODAY-TONIGHT...WINDS AT 41009 FINALLY PICKED UP TO ADVISORY LEVELS IN THE LAST FEW HOURS. SHORT RANGE GUIDANCE INDICATES A WEAKENING PRESSURE GRADIENT BY LATE THIS MORNING AS HIGH PRESSURE RIDGE NOSES IN BEHIND SLOW MOVING FRONTAL BOUNDARY THAT WILL SETTLE JUST SOUTH OF THE WATERS. DUE TO RECENT BUOY TRENDS...WILL EXTEND THE ADVISORY A LITTLE LONGER FOR THE OFFSHORE WATERS. THE RAP AND LOCAL WRF MODELS SHOW THE 20 KNOT WINDS ABATING AROUND 9 AM. WINDS SHOULD THEN DROP BELOW 10 KNOTS THIS AFTERNOON AND INTO EARLY EVENING. THE FRONT WILL SAG BACK TO THE SOUTH TONIGHT WITH THE MODELS INDICATING A NORTHWEST WIND SURGE 15-20 KNOTS AFTER MIDNIGHT. THU-SUN...W/NW WINDS WILL PERSIST INTO LATE WEEK AND THROUGH THE WEEKEND. PERIODS OF INCREASING WINDS UP TO NEAR/AROUND 20 KNOTS WILL OCCUR AND CREATE ROUGHER BOATING CONDITIONS...ESPECIALLY OFFSHORE. && .FIRE WEATHER... TODAY...MIN RH VALUES SHOULD FALL TO AROUND 35 PERCENT ACROSS THE INTERIOR FROM OSCEOLA NORTH. THU-FRI...DRY AIRMASS OVER THE AREA WILL PRODUCE MIN RH VALUES AROUND 30 TO 35 PERCENT OVER MUCH OF THE AREA EACH AFTERNOON. HOWEVER WIND SPEEDS EXPECTED TO REMAIN JUST BELOW 15 MPH BOTH DAYS. && .PRELIMINARY POINT TEMPS/POPS... DAB 72 47 73 48 / 10 0 0 0 MCO 77 50 75 51 / 10 10 0 0 MLB 75 51 74 52 / 10 10 0 0 VRB 76 50 74 50 / 20 10 0 0 LEE 74 49 73 49 / 10 0 0 0 SFB 75 49 75 49 / 10 0 0 0 ORL 76 52 74 52 / 10 10 0 0 FPR 75 54 74 50 / 20 10 0 0 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 9 AM THIS MORNING FOR WATERS FROM FLAGLER BEACH TO VOLUSIA BREVARD COUNTY LINE 20 TO 60 NM OFFSHORE-WATERS FROM VOLUSIA BREVARD COUNTY LINE TO SEBASTIAN INLET 20 TO 60 NM OFFSHORE. && $$ SHORT TERM/AVIATION...LASCODY LONG TERM....WEITLICH
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1156 PM CST TUE FEB 26 2013 .UPDATE... INITIAL UPPER LOW IS LIFTING NORTHEAST THROUGH THE LOWER OHIO VALLEY THIS EVENING WHILE THE SECOND UPPER LEVEL SYSTEM IS PROGRESSING EAST THROUGH KANSAS. SEVERAL IMPULSES AREA MOVING AROUND THE CYCLONIC FLOW AND ARE HELPING FLARE UP BANDS OF SNOW AS THEY PASS THROUGH CENTRAL IA. ONE IMPULSE HAS SETTLED SOUTH INTO NORTHERN MISSOURI WHILE THE NEXT IS NOW MOVING INTO NORTHEAST IOWA OUT OF WISCONSIN WHILE ANOTHER IS BACK FARTHER EAST AND JUST MOVING WEST FROM LAKE SUPERIOR. BETWEEN THE ENERGY...DRIER AIR HAS FILTERED SOUTH AND NOW COVERS NEARLY THE NORTHWEST HALF OF THE STATE AND HAS TEMPORARILY BROUGHT AN END TO THE SNOW OVER NORTHWEST HEADLINE AREAS. IMPULSE MOVING INTO NORTHEAST IOWA WILL HELP SHIFT ANOTHER BAND OF SNOW WESTWARD ACROSS THESE REGIONS. LATEST SREF 100 MB DEPTH DENDRITIC GROWTH ZONE REMAINS LOCKED ON TO THESE ENHANCED BANDS. TRENDS CONTINUE TO SUGGEST THE FOCUS FOR DENDRITIC SNOW IS OVER CENTRAL IOWA THROUGH NOON WEDNESDAY. ANOTHER 1 TO 3 INCHES LIKELY THROUGH THIS TIME THROUGH THE WARNED AREA. && .SHORT TERM /TONIGHT/... WINTER STORM WILL PERSIST THROUGH WEDNESDAY MORNING AS LIGHT TO MODERATE SNOW BANDING CONTINUES ON THE BACKSIDE OF THE SURFACE LOW LOCATED IN SOUTHEAST MISSOURI. SURFACE LOW LOOKS TO SLOWLY MIGRATE NORTHEAST FROM SOUTHEAST MISSOURI INTO CENTRAL ILLINOIS THIS EVENING INTO TOMORROW MORNING. LEANED TOWARD A SREF/GFS/NAM12 BLEND FOR TRENDS TONIGHT. WEAK LIFT WITHIN THE DENDRITIC GROWTH ZONE CONTINUES THIS AFTERNOON AND TONIGHT...AND EVEN PERSISTS INTO WEDNESDAY MORNING. HIGHER CONFIDENCE WITH THE ADDITIONAL LIGHT SNOW AMOUNTS THROUGH WEDNESDAY MORNING RESULTING IN ROUGHLY 1 TO 4 INCHES OF ADDITIONAL SNOW THROUGH 12Z ACROSS THE WARNING AREA. THE SNOW BAND AXIS LOOKS TO CONTINUE TO SLOWLY PIVOT COUNTERCLOCKWISE AROUND THE CENTRAL PORTION OF THE FORECAST RESULTING IN SOME AREAS RECEIVING AN ELONGATED PERIOD OF MODERATE TO BRIEF HEAVY SNOW THIS EVENING. WITH THE CURRENT TRACK OF THE SURFACE LOW...NOT EXPECTING THIS BAND TO DRIFT SOUTHEAST ALL THAT MUCH UNTIL EARLY WEDNESDAY MORNING. GENERALLY EXPECTING A HALF TO POSSIBLY ONE INCH PER HOUR SNOWFALL RATES THIS EVENING WITH THE WEAK LIFT IN THE DENDRITIC LAYER. SREF 100MB/50MB DENDRITE GROWTH ZONE PARAMETER DEPICTING 80-90 PERCENT PROBABILITY OF DENDRITIC SNOW THROUGH TOMORROW AND MATCHES UP WELL WITH PREVIOUSLY MENTION BAND PIVOTING ACROSS CENTRAL IOWA. BUFR SOUNDINGS REMAIN DEEPLY SATURATED THROUGH WEDNESDAY MORNING...WITH THE RAP SHOWING A MID LEVEL DRY LAYER ADVECTING INTO DSM TO ALO AND MAY SEE A BRIEF BREAK IN THE SNOW MID TO LATE EVENING. WINDS ATOP THE MIXED LAYER RANGE FROM 25 TO 30KTS THIS AFTERNOON AND TONIGHT AND EXPECTING BLOWING SNOW IMPACTS TO CONTINUE AS WELL. LEANED TOWARDS THE GFS/SREF QPF AMOUNTS TONIGHT AS NAM SEEMS TO HIGH ACROSS THE EAST...ESPECIALLY WITH THE WEAKER FORCING. .LONG TERM /WEDNESDAY THROUGH TUESDAY/... WEAKER LIFT WILL PERSIST INTO WEDNESDAY WITH THE SPC SREF INDICATING DEEP DENDRITIC GROWTH LAYER CONTINUING THROUGH CENTRAL IOWA. ALL SOUNDINGS CONTINUE TO ALSO SHOW DEEP SATURATION THROUGH AT LEAST MIDDAY TOMORROW AND ANTICIPATE THE LIGHT SNOW TO CONTINUE. HAVE GONE WITH LIKELY TO CATEGORICAL POPS FOR MUCH OF THE AREA UNDER THE CURRENT HEADLINE WITH THE SHARP CUTOFF ON THE NORTHERN SIDE OF THE PCPN AREA PERSISTING. WINDS WILL REMAIN RATHER STRONG THROUGH THE DAY WITH BRISK NORTHWEST FLOW PERSISTING WITH DECENT PRESSURE GRADIENT. EVENTUALLY...THE FORCING WILL BE DIMINISHING WITH THE SNOW TAPERING TO FLURRIES BY LATER IN THE DAY. CLOUDINESS IS EXPECTED TO PERSIST AS WELL IN CYCLONIC FLOW ON BACKSIDE INTO WEDNESDAY NIGHT WITH AN APPROACHING SHORTWAVE ON THURSDAY AND THURSDAY NIGHT HELPING THE CLOUDINESS TO MAINTAIN. IN FACT...SOME WEAK LIFT WITH THIS PASSING WAVE ON FRIDAY MAY HELP TO PRODUCE SOME FLURRIES IN SOUTHERN IOWA DURING THE DAY. UPPER RIDGING WILL SLIDE THROUGH THE REGION INTO THE WEEKEND WITH QUIET WEATHER DURING THIS TIME. TEMPERATURES WILL REMAIN BELOW NORMAL WITH WIDESPREAD SNOW PACK AND ONLY WEAK ADVECTION UNTIL SUNDAY NIGHT. THIS WARM ADVECTION IS IN ADVANCE OF THE NEXT SYSTEM WHICH WILL PASS THROUGH THE REGION ON MONDAY INTO TUESDAY IN BROAD NORTHWEST FLOW. BOTH GFS AND EURO HAVE INDICATED SOME DECENT FORCING AND ANTICIPATE PCPN DEVELOPING AND SLIDING ACROSS THE STATE ON MONDAY INTO EARLY TUESDAY. SOUNDINGS WOULD INDICATE GENERALLY SNOW DURING THIS TIME ACROSS THE STATE WITH LIGHT TO MODERATE ACCUMULATIONS EXPECTED. && .AVIATION...27/06Z BANDS OF LIGHT TO MODERATE SNOW WILL CONTINUE OVERNIGHT ALONG WITH MVFR TO IFR CIGS. THE CIGS SHOULD MOVE INTO THE KFOD/KMCW AREAS OVERNIGHT AS WELL AFTER BEGINNING VFR. SNOW WILL GRADUALLY DIMINISH AFTERNOON ON WEDNESDAY HOWEVER IFR TO MVFR CIGS LIKELY TO CONTINUE THROUGH THE PERIOD. BREEZY NORTHERLY WINDS OVERNIGHT WILL BECOME GUSTY AGAIN ON WEDNESDAY. && .DMX WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL NOON CST WEDNESDAY FOR ADAIR-ADAMS- APPANOOSE-BLACK HAWK-BOONE-CLARKE-DALLAS-DAVIS-DECATUR-GRUNDY- HARDIN-JASPER-LUCAS-MADISON-MAHASKA-MARION-MARSHALL-MONROE-POLK- POWESHIEK-RINGGOLD-STORY-TAMA-TAYLOR-UNION-WAPELLO-WARREN-WAYNE. WINTER WEATHER ADVISORY UNTIL NOON CST WEDNESDAY FOR AUDUBON- BREMER-BUTLER-CASS-FRANKLIN-GREENE-GUTHRIE-HAMILTON. && $$ UPDATE...DONAVON SHORT TERM...PODRAZIK LONG TERM...COGIL AVIATION...DONAVON
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1101 PM CST TUE FEB 26 2013 .UPDATE... INITIAL UPPER LOW IS LIFTING NORTHEAST THROUGH THE LOWER OHIO VALLEY THIS EVENING WHILE THE SECOND UPPER LEVEL SYSTEM IS PROGRESSING EAST THROUGH KANSAS. SEVERAL IMPULSES AREA MOVING AROUND THE CYCLONIC FLOW AND ARE HELPING FLARE UP BANDS OF SNOW AS THEY PASS THROUGH CENTRAL IA. ONE IMPULSE HAS SETTLED SOUTH INTO NORTHERN MISSOURI WHILE THE NEXT IS NOW MOVING INTO NORTHEAST IOWA OUT OF WISCONSIN WHILE ANOTHER IS BACK FARTHER EAST AND JUST MOVING WEST FROM LAKE SUPERIOR. BETWEEN THE ENERGY...DRIER AIR HAS FILTERED SOUTH AND NOW COVERS NEARLY THE NORTHWEST HALF OF THE STATE AND HAS TEMPORARILY BROUGHT AN END TO THE SNOW OVER NORTHWEST HEADLINE AREAS. IMPULSE MOVING INTO NORTHEAST IOWA WILL HELP SHIFT ANOTHER BAND OF SNOW WESTWARD ACROSS THESE REGIONS. LATEST SREF 100 MB DEPTH DENDRITIC GROWTH ZONE REMAINS LOCKED ON TO THESE ENHANCED BANDS. TRENDS CONTINUE TO SUGGEST THE FOCUS FOR DENDRITIC SNOW IS OVER CENTRAL IOWA THROUGH NOON WEDNESDAY. ANOTHER 1 TO 3 INCHES LIKELY THROUGH THIS TIME THROUGH THE WARNED AREA. && .SHORT TERM /TONIGHT/... WINTER STORM WILL PERSIST THROUGH WEDNESDAY MORNING AS LIGHT TO MODERATE SNOW BANDING CONTINUES ON THE BACKSIDE OF THE SURFACE LOW LOCATED IN SOUTHEAST MISSOURI. SURFACE LOW LOOKS TO SLOWLY MIGRATE NORTHEAST FROM SOUTHEAST MISSOURI INTO CENTRAL ILLINOIS THIS EVENING INTO TOMORROW MORNING. LEANED TOWARD A SREF/GFS/NAM12 BLEND FOR TRENDS TONIGHT. WEAK LIFT WITHIN THE DENDRITIC GROWTH ZONE CONTINUES THIS AFTERNOON AND TONIGHT...AND EVEN PERSISTS INTO WEDNESDAY MORNING. HIGHER CONFIDENCE WITH THE ADDITIONAL LIGHT SNOW AMOUNTS THROUGH WEDNESDAY MORNING RESULTING IN ROUGHLY 1 TO 4 INCHES OF ADDITIONAL SNOW THROUGH 12Z ACROSS THE WARNING AREA. THE SNOW BAND AXIS LOOKS TO CONTINUE TO SLOWLY PIVOT COUNTERCLOCKWISE AROUND THE CENTRAL PORTION OF THE FORECAST RESULTING IN SOME AREAS RECEIVING AN ELONGATED PERIOD OF MODERATE TO BRIEF HEAVY SNOW THIS EVENING. WITH THE CURRENT TRACK OF THE SURFACE LOW...NOT EXPECTING THIS BAND TO DRIFT SOUTHEAST ALL THAT MUCH UNTIL EARLY WEDNESDAY MORNING. GENERALLY EXPECTING A HALF TO POSSIBLY ONE INCH PER HOUR SNOWFALL RATES THIS EVENING WITH THE WEAK LIFT IN THE DENDRITIC LAYER. SREF 100MB/50MB DENDRITE GROWTH ZONE PARAMETER DEPICTING 80-90 PERCENT PROBABILITY OF DENDRITIC SNOW THROUGH TOMORROW AND MATCHES UP WELL WITH PREVIOUSLY MENTION BAND PIVOTING ACROSS CENTRAL IOWA. BUFR SOUNDINGS REMAIN DEEPLY SATURATED THROUGH WEDNESDAY MORNING...WITH THE RAP SHOWING A MID LEVEL DRY LAYER ADVECTING INTO DSM TO ALO AND MAY SEE A BRIEF BREAK IN THE SNOW MID TO LATE EVENING. WINDS ATOP THE MIXED LAYER RANGE FROM 25 TO 30KTS THIS AFTERNOON AND TONIGHT AND EXPECTING BLOWING SNOW IMPACTS TO CONTINUE AS WELL. LEANED TOWARDS THE GFS/SREF QPF AMOUNTS TONIGHT AS NAM SEEMS TO HIGH ACROSS THE EAST...ESPECIALLY WITH THE WEAKER FORCING. .LONG TERM /WEDNESDAY THROUGH TUESDAY/... WEAKER LIFT WILL PERSIST INTO WEDNESDAY WITH THE SPC SREF INDICATING DEEP DENDRITIC GROWTH LAYER CONTINUING THROUGH CENTRAL IOWA. ALL SOUNDINGS CONTINUE TO ALSO SHOW DEEP SATURATION THROUGH AT LEAST MIDDAY TOMORROW AND ANTICIPATE THE LIGHT SNOW TO CONTINUE. HAVE GONE WITH LIKELY TO CATEGORICAL POPS FOR MUCH OF THE AREA UNDER THE CURRENT HEADLINE WITH THE SHARP CUTOFF ON THE NORTHERN SIDE OF THE PCPN AREA PERSISTING. WINDS WILL REMAIN RATHER STRONG THROUGH THE DAY WITH BRISK NORTHWEST FLOW PERSISTING WITH DECENT PRESSURE GRADIENT. EVENTUALLY...THE FORCING WILL BE DIMINISHING WITH THE SNOW TAPERING TO FLURRIES BY LATER IN THE DAY. CLOUDINESS IS EXPECTED TO PERSIST AS WELL IN CYCLONIC FLOW ON BACKSIDE INTO WEDNESDAY NIGHT WITH AN APPROACHING SHORTWAVE ON THURSDAY AND THURSDAY NIGHT HELPING THE CLOUDINESS TO MAINTAIN. IN FACT...SOME WEAK LIFT WITH THIS PASSING WAVE ON FRIDAY MAY HELP TO PRODUCE SOME FLURRIES IN SOUTHERN IOWA DURING THE DAY. UPPER RIDGING WILL SLIDE THROUGH THE REGION INTO THE WEEKEND WITH QUIET WEATHER DURING THIS TIME. TEMPERATURES WILL REMAIN BELOW NORMAL WITH WIDESPREAD SNOW PACK AND ONLY WEAK ADVECTION UNTIL SUNDAY NIGHT. THIS WARM ADVECTION IS IN ADVANCE OF THE NEXT SYSTEM WHICH WILL PASS THROUGH THE REGION ON MONDAY INTO TUESDAY IN BROAD NORTHWEST FLOW. BOTH GFS AND EURO HAVE INDICATED SOME DECENT FORCING AND ANTICIPATE PCPN DEVELOPING AND SLIDING ACROSS THE STATE ON MONDAY INTO EARLY TUESDAY. SOUNDINGS WOULD INDICATE GENERALLY SNOW DURING THIS TIME ACROSS THE STATE WITH LIGHT TO MODERATE ACCUMULATIONS EXPECTED. && .AVIATION...26/18Z AREAS OF LIGHT TO MODERATE SNOW WILL CONTINUE TO IMPACT THE KDSM/KOTM/KALO AREAS THROUGH TONIGHT. A MIX OF MVFR TO IFR STRATUS WILL ACCOMPANY THE SNOW. KFOD AND KMCW WILL HAVE LESS SNOW THOUGH PERIODS OF MVFR STRATUS OR LOWER ARE POSSIBLE AT TIMES. GUSTY NORTHERLY WINDS WILL PREVAIL THROUGH WEDNESDAY && .DMX WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL NOON CST WEDNESDAY FOR ADAIR-ADAMS- APPANOOSE-BLACK HAWK-BOONE-CLARKE-DALLAS-DAVIS-DECATUR-GRUNDY- HARDIN-JASPER-LUCAS-MADISON-MAHASKA-MARION-MARSHALL-MONROE-POLK- POWESHIEK-RINGGOLD-STORY-TAMA-TAYLOR-UNION-WAPELLO-WARREN-WAYNE. WINTER WEATHER ADVISORY UNTIL NOON CST WEDNESDAY FOR AUDUBON- BREMER-BUTLER-CASS-FRANKLIN-GREENE-GUTHRIE-HAMILTON. && $$ UPDATE...DONAVON SHORT TERM...PODRAZIK LONG TERM...COGIL AVIATION...DONAVON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
332 AM EST WED FEB 27 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 428 PM EST TUE FEB 26 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW PRONOUNCED SPLIT FLOW CONTINUING ACROSS NAMERICA. IN WHAT HAS BEEN A VERY ACTIVE SRN STREAM RECENTLY...A WELL-DEFINED MID LEVEL LOW IS MOVING ENE INTO THE LWR OHIO VALLEY. SRN STREAM RIDGING AHEAD OF FEATURE EXTENDS FROM JUST OFF THE SE COAST TO SRN NEW ENGLAND AND THEN BACK INTO THE UPPER LAKES. WITH NRN STREAM WELL N OF HERE...ARCTIC AIR HAS RETREATED INTO NRN CANADA. CLOSER TO HOME...PESKY STRATOCU HAS CONTINUED TO PLAGUE UPPER MI TODAY. HOWEVER...ROUGHLY THE W THIRD OF THE FCST AREA HAS ENJOYED MOSTLY SUNNY SKIES FOR AT LEAST A PORTION OF THE DAY. THE POCKET OF MOSTLY SUNNY SKIES CURRENTLY OVER THE W IS SHOWING SIGNS OF EXPANDING EASTWARD AS STRONGER DAYTIME HEATING UNDER HIGHER LATE FEB SUN ANGLE IS WORKING ON LOWER ALBEDO FORESTED TERRAIN TO RAISE MIXED LAYER AND THUS MIX OUT THE SHALLOW MOIST LAYER. DURING THE SHORT TERM...MAIN FCST ISSUE WILL REVOLVE AROUND NORTHWARD PROGESS OF A WEAKENING PCPN SHIELD SPREADING N AROUND SRN STREAM MID LEVEL LOW AS IT TRACKS INTO THE UPPER OHIO VALLEY/LWR LAKES REGION. EARLY ON...LOW CLOUDS WILL CONTINUE TO PRESENT SOME ISSUES. CLEARING MAY CONTINUE TO EXPAND E FROM WRN UPPER MI OVER THE NEXT COUPLE OF HRS...BUT WITH LOSS OF DAYTIME HEATING...STRATOCU WILL PROBABLY TEND TO SPREAD BACK INTO THE AREAS THAT HAVE CLEARED...ESPECIALLY IF THE STRATOCU TO THE E AND NE DOES NOT BREAK UP DURING THE LATE AFTN/EVENING. LATEST VIS SATELLITE IMAGERY DOES SHOW STRATOCU THINNING OVER ERN LAKE SUPERIOR...SO THERE MAY YET BE SOME MORE CLEARING DURING THE EVENING. WILL BE A TREND TO MONITOR. WHILE CLOUDS WILL AGAIN MAKE OR BREAK TEMP FCST...THERE WILL LIKELY NOT BE AS GREAT OF A TEMP SPREAD TONIGHT AS IN PREVIOUS NIGHTS BTWN AREAS WITH CLOUDS AND AREAS WITH LESS CLOUD SINCE INCREASING GRADIENT WINDS WILL LIMIT RADIATIONAL COOLING. TRENDED TEMPS TOWARD RAW MODEL GUIDANCE WHICH PUTS MIN TEMPS GENERALLY IN THE MID/UPPER 20S. AS FOR PCPN...THE STRONG ISENTROPIC ASCENT COMPONENT TO PCPN SHIELD SPREADING N INTO SRN WI/SRN MI ATTM WILL GRADUALLY FADE WITH TIME AS THE ZONE OF STRONG ASCENT TRANSLATES EASTWARD...RESULTING IN ZONE OF HEAVIEST PCPN SHIFTING E TOWARD THE LWR LAKES/SRN NEW ENGLAND TONIGHT/WED MORNING. THUS...A DECAYING SHIELD OF PCPN WILL BE LIFTING TOWARD UPPER MI TONIGHT/WED MORNING. RECENT MODEL TRENDS GENERALLY POINT TOWARD A MORE AGGRESSIVE PUSH OF LIGHT SNOW INTO UPPER MI. GIVEN THE STRONG NORTHWARD PUSH OF PCPN THRU LWR MI ATTM AND THE LACK OF A LAYER OF VERY DRY AIR AT THE LOWER LEVELS TO THE N ACROSS UPPER MI...HAVE OPTED TO TREND PCPN CHC SLIGHTLY FARTHER N THAN PREVIOUS FCST TO ROUGHLY A KERY/KSAW/KIMT LINE AND RAISED POPS TO HIGH CHC ALONG LAKE MI. WITH 850MB TEMPS NO LWR THAN -8/-9C... IT`S VERY UNLIKELY THAT ANY LES WILL DEVELOP OFF LAKE SUPERIOR UNDER STRONG NE CYCLONIC FLOW WED. IF SHIELD OF LIGHT SYNOPTIC SNOW DOES REACH LAKE SUPERIOR...THEN A LITTLE LAKE COMPONENT WILL BE THERE. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 331 AM EST WED FEB 27 2013 THURSDAY THROUGH FRIDAY...VERTICALLY STACKED SURFACE AND UPPER LEVEL 500MB CLOSED LOW LOCATED OVER THE LOWER GREAT LAKES THURSDAY MORNING WILL SHIFT EASTWARD INTO THE NORTHEASTERN U.S. BY THURSDAY NIGHT. IT DOES APPEAR AS THOUGH ENOUGH MOISTURE WILL REMAIN IN PLACE DURING THIS TIME PERIOD TO KEEP LAKE EFFECT SNOW SHOWERS OVER AREAS FAVORED BY A NORTH-NORTHEAST WIND. H850 TEMPERATURES ARE EXPECTED TO COOL TO AROUND -10 TO -12C WHICH WOULD BE SUPPORTIVE OF LAKE EFFECT SNOW SHOWERS AS LAKE TEMPERATURES ARE AVERAGING BETWEEN 1 AND 2C. AS MENTIONED BY THE PREVIOUS SHIFT INVERSION HEIGHTS LOOK TO REMAIN AROUND 3-4KFT...THIS COUPLED WITH A FAIRLY SHALLOW CLOUD LAYER WOULD HELP TO LIMIT SNOW ACCUMULATION AS LITTLE IF ANY MOISTURE/LIFT IS COLLOCATED WITH THE DGZ. LATE THURSDAY NIGHT SURFACE HIGH PRESSURE WILL BUILD FROM JAMES BAY INTO THE UPPER GREAT LAKES. AT THE SAME TIME A 500MB RIDGE WILL BUILD ACROSS THE AREA AS WELL. THE COMBINATION OF WARMING ALOFT ALONG WITH DRY AIR FROM CANADA WRAPPING IN FROM THE NORTH WILL HELP DIMINISH THE SNOW SHOWERS THROUGH THE EARLY MORNING HOURS FRIDAY. THE REMAINDER OF FRIDAY LOOKS TO BE DRY AT THIS POINT. FRIDAY NIGHT THROUGH SUNDAY NIGHT...THE SURFACE RIDGE AND DRY AIR ARE PROGGED TO REMAIN IN PLACE OVER MUCH OF THE UPPER GREAT LAKES REGION THROUGH THIS TIME PERIOD HELPING TO LIMIT PRECIPITATION CHANCES. THE LACK OF MOISTURE WILL ALSO HELP TO KEEP SKIES PARTLY CLOUDY TO MOSTLY CLEAR THROUGH THIS TIME FRAME AS WELL. TEMPERATURES ARE EXPECTED TO BE NEAR TO SLIGHTLY BELOW NORMAL THROUGH THIS TIME PERIOD AS H850 TEMPS ARE EXPECTED TO BE BETWEEN -12C AND -14C. MONDAY THROUGH TUESDAY NIGHT...UPPER LEVEL 500MB TROUGH IS EXPECTED TO REMAIN IN PLACE OVER MUCH OF THE EASTERN SEABOARD THROUGH THIS TIME PERIOD AS SHOWN BY THE 00Z GFS/EC/GEM. MONDAY MORNING A LOW PRESSURE SYSTEMS IS PROGGED TO DEVELOP OVER THE CENTRAL PLAINS AT THE SAME TIME THAT AN UPPER LEVEL 500MB TROUGH DIGS INTO THE PLAINS. MODELS ARE IN GENERAL AGREEMENT THAT THE LOW WILL REMAIN SOUTH OF THE UPPER PENINSULA AS THE SURFACE HIGH PRESSURE SYSTEM REMAINS IN PLACE OVER MUCH OF THE UPPER MIDWEST...SHIFTING SLIGHTLY WEST MONDAY NIGHT INTO TUESDAY MORNING. THE 00Z GFS/EC ALONG WITH THE GFS ENSEMBLE MEMBERS KEEP THE LOW SOUTH OF THE AREA...WITH THE LOW PASSING ALONG OR JUST NORTH OF THE AR/MO BORDER. MODELS ALSO INDICATED COLDER AIR AT H850 SHIFTING INTO THE REGION WITH WINDS OUT OF THE NORTH. H850 TEMPS ARE PROGGED TO BE BETWEEN -10 AND -13C WHILE MOISTURE BETWEEN 1000-850MB IS EXPECTED TO INCREASE. THIS SHOULD ALLOW LAKE EFFECT SNOW SHOWERS TO DEVELOP OVER NORTH WIND FAVORED SNOW BELTS. DECIDED TO MENTION ONLY SLIGHT CHANCES MONDAY NIGHT INTO TUESDAY AS THIS IS STILL SEVERAL DAYS OUT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1201 AM EST WED FEB 27 2013 MOIST NE FLOW SHOULD GENERALLY MAINTAIN MVFR CLOUDS THROUGH PD AT ALL TAF SITES. DOWNSLOPING FLOW AT KCMX COULD PERHAPS LEAD TO BRIEF BREAKS IN CLOUDS THERE...BUT OTHERWISE INCREASINGLY MOIST NE FLOW SHOULD ENSURE LOW CLOUDS THROUGH FCST PD. KSAW COULD SEE SOME AFTERNOON FLURRIES FROM DEEPER MOISTURE WRAPPING BACK INTO AREA FROM SYSTEM LIFTING THROUGH LOWER LAKES. TIGHTENING PRES GRAD WILL ALLOW NE WINDS TO GUST NEAR 25 KTS BY LATE WED MORNING/EARLY AFTERNOON...ESPECIALLY AT KSAW && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 428 PM EST TUE FEB 26 2013 TIGHTENING PRES GRADIENT BTWN HIGH PRES TO THE N AND NW AND LOW PRES TRACKING THRU THE LWR OHIO VALLEY TO LWR LAKES WILL RESULT IN NORTHEASTERLY WINDS ACROSS LAKE SUPERIOR INCREASING TO 20-30KT TONIGHT THRU WED. MIGHT SEE A FEW GALE FORCE GUSTS WED AFTN OVER THE E HALF. EVEN THOUGH THE LOW CONTINUES TO MOVE E THU...THE HIGH BUILDING TOWARD THE AREA FROM N WILL MAINTAIN A TIGHT PRES GRADIENT...RESULTING IN CONTINUED 20-30KT WINDS WITH SOME GALE FORCE GUSTS POSSIBLE OVER THE E HALF THRU THU MORNING. WINDS WILL THEN VERY SLOWLY DIMINISH FROM W TO E FRI/SAT AS THE HIGH PRES MOVES CLOSER...BUT IT WILL PROBABLY BE SAT BEFORE WINDS DROP BLO 20KT ACROSS THE ENTIRE LAKE. THE PERIOD OF STRONG WINDS WED NIGHT THRU FRI WILL ALSO BRING THE POTENTIAL FOR FREEZING SPRAY. LIGHT WINDS UNDER 10KT ARE EXPECTED SUN AS SFC HIGH PRES RIDGE WILL EXTEND FROM HUDSON BAY S ACROSS LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... GALE WARNING FROM 7 PM THIS EVENING TO 10 AM EST THURSDAY FOR LSZ244-245-248>250-264>267. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...KEC AVIATION...VOSS MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1202 AM EST WED FEB 27 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 428 PM EST TUE FEB 26 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW PRONOUNCED SPLIT FLOW CONTINUING ACROSS NAMERICA. IN WHAT HAS BEEN A VERY ACTIVE SRN STREAM RECENTLY...A WELL-DEFINED MID LEVEL LOW IS MOVING ENE INTO THE LWR OHIO VALLEY. SRN STREAM RIDGING AHEAD OF FEATURE EXTENDS FROM JUST OFF THE SE COAST TO SRN NEW ENGLAND AND THEN BACK INTO THE UPPER LAKES. WITH NRN STREAM WELL N OF HERE...ARCTIC AIR HAS RETREATED INTO NRN CANADA. CLOSER TO HOME...PESKY STRATOCU HAS CONTINUED TO PLAGUE UPPER MI TODAY. HOWEVER...ROUGHLY THE W THIRD OF THE FCST AREA HAS ENJOYED MOSTLY SUNNY SKIES FOR AT LEAST A PORTION OF THE DAY. THE POCKET OF MOSTLY SUNNY SKIES CURRENTLY OVER THE W IS SHOWING SIGNS OF EXPANDING EASTWARD AS STRONGER DAYTIME HEATING UNDER HIGHER LATE FEB SUN ANGLE IS WORKING ON LOWER ALBEDO FORESTED TERRAIN TO RAISE MIXED LAYER AND THUS MIX OUT THE SHALLOW MOIST LAYER. DURING THE SHORT TERM...MAIN FCST ISSUE WILL REVOLVE AROUND NORTHWARD PROGESS OF A WEAKENING PCPN SHIELD SPREADING N AROUND SRN STREAM MID LEVEL LOW AS IT TRACKS INTO THE UPPER OHIO VALLEY/LWR LAKES REGION. EARLY ON...LOW CLOUDS WILL CONTINUE TO PRESENT SOME ISSUES. CLEARING MAY CONTINUE TO EXPAND E FROM WRN UPPER MI OVER THE NEXT COUPLE OF HRS...BUT WITH LOSS OF DAYTIME HEATING...STRATOCU WILL PROBABLY TEND TO SPREAD BACK INTO THE AREAS THAT HAVE CLEARED...ESPECIALLY IF THE STRATOCU TO THE E AND NE DOES NOT BREAK UP DURING THE LATE AFTN/EVENING. LATEST VIS SATELLITE IMAGERY DOES SHOW STRATOCU THINNING OVER ERN LAKE SUPERIOR...SO THERE MAY YET BE SOME MORE CLEARING DURING THE EVENING. WILL BE A TREND TO MONITOR. WHILE CLOUDS WILL AGAIN MAKE OR BREAK TEMP FCST...THERE WILL LIKELY NOT BE AS GREAT OF A TEMP SPREAD TONIGHT AS IN PREVIOUS NIGHTS BTWN AREAS WITH CLOUDS AND AREAS WITH LESS CLOUD SINCE INCREASING GRADIENT WINDS WILL LIMIT RADIATIONAL COOLING. TRENDED TEMPS TOWARD RAW MODEL GUIDANCE WHICH PUTS MIN TEMPS GENERALLY IN THE MID/UPPER 20S. AS FOR PCPN...THE STRONG ISENTROPIC ASCENT COMPONENT TO PCPN SHIELD SPREADING N INTO SRN WI/SRN MI ATTM WILL GRADUALLY FADE WITH TIME AS THE ZONE OF STRONG ASCENT TRANSLATES EASTWARD...RESULTING IN ZONE OF HEAVIEST PCPN SHIFTING E TOWARD THE LWR LAKES/SRN NEW ENGLAND TONIGHT/WED MORNING. THUS...A DECAYING SHIELD OF PCPN WILL BE LIFTING TOWARD UPPER MI TONIGHT/WED MORNING. RECENT MODEL TRENDS GENERALLY POINT TOWARD A MORE AGGRESSIVE PUSH OF LIGHT SNOW INTO UPPER MI. GIVEN THE STRONG NORTHWARD PUSH OF PCPN THRU LWR MI ATTM AND THE LACK OF A LAYER OF VERY DRY AIR AT THE LOWER LEVELS TO THE N ACROSS UPPER MI...HAVE OPTED TO TREND PCPN CHC SLIGHTLY FARTHER N THAN PREVIOUS FCST TO ROUGHLY A KERY/KSAW/KIMT LINE AND RAISED POPS TO HIGH CHC ALONG LAKE MI. WITH 850MB TEMPS NO LWR THAN -8/-9C... IT`S VERY UNLIKELY THAT ANY LES WILL DEVELOP OFF LAKE SUPERIOR UNDER STRONG NE CYCLONIC FLOW WED. IF SHIELD OF LIGHT SYNOPTIC SNOW DOES REACH LAKE SUPERIOR...THEN A LITTLE LAKE COMPONENT WILL BE THERE. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 428 PM EST TUE FEB 26 2013 LITTLE CHANGES TO THE LONG TERM FROM 24 HOURS AGO...WITH THE MAIN ITEM OF DIFFERENCE A SLIGHT WOBBLE TO THE NORTHWEST WITH THE SYSTEM CURRENTLY MOVING THROUGH THE MID MISSISSIPPI VALLEY THAT WILL MOVE THROUGH THE LOWER GREAT LAKES. THIS SLIGHT ADJUSTMENT...PUSHES THE PRECIPITATION A TOUCH FARTHER INLAND FROM LAKE MICHIGAN. BUT AS THE LONG TERM PERIOD BEGINS...THE LOW WILL START IT/S EASTWARD SHIFT TOWARDS NEW YORK AND DIMINISH THE SNOW ALONG THE LAKE MICHIGAN SHORELINE. ATTENTION THEN TURNS TO THE AMOUNT OF MOISTURE AND COLD AIR IN THE LOWER LEVELS TO SUPPORT LAKE ENHANCED AND UPSLOPE SNOW SHOWERS. LATEST TRENDS IN THE MOISTURE AND COLD AIR /850MB TEMPERATURES FALLING FROM -9C AT WEDNESDAY NIGHT TO -13C BETWEEN 900-850MB BY THURSDAY AFTERNOON/ LEADS TO GREATER CONFIDENCE IN SCATTERED SNOW SHOWERS OCCURRING FOR LOCATIONS NEAR LAKE SUPERIOR FROM PICTURED ROCKS AND WESTWARD. INVERSION HEIGHTS AROUND 3-4KFT SHOULD KEEP THE INTENSITY IN CHECK AND HELPS KEEP LAKE INDUCED CAPES BELOW 200 J/KG. THUS...WILL BUMP POPS UP 5-10 PERCENT INTO HIGHER END CHANCE CATEGORY. SNOWFALL AMOUNTS SHOULD BE FAIRLY LIGHT...SINCE CLOUD DEPTH IS FAIRLY LIMITED. WITH THE INITIAL CLOUD LAYER MAINLY BEING BELOW THE DGZ WEDNESDAY NIGHT...WOULD EXPECT FLAKES TO BE FAIRLY SMALL. BUT AS THE COLDER AIR ARRIVES...IT DOES ATTEMPT TO PUSH THE CLOUD LAYER INTO THE DGZ AND HELP SNOW RATIOS. BUT WITH THE LIMITED CLOUD DEPTH/MOISTURE TO WORK WITH...WOULDN/T EXPECT MUCH MORE THAN AN INCH OR TWO OF TOTAL ACCUMULATION BY THE TIME IT STARTS WINDING DOWN ON FRIDAY. THE HIGHEST AMOUNTS WILL BE IN THE FAVORED UPSLOPE LOCATIONS WITH NORTHEAST WINDS...ESPECIALLY IN/NEAR THE HURON MOUNTAINS WHICH COULD APPROACH 3 INCHES. A BUILDING CANADIAN HIGH OVER HUDSON BAY WILL SLIDE A RIDGE SOUTH INTO THE UPPER GREAT LAKES REGION FRIDAY AND IT WILL REMAIN INTO THE FIRST PART OF THE NEXT WEEK. THIS WILL WORK TO REDUCE THE INVERSION HEIGHTS TO 2KFT AND SHOULD BRING AN END TO THE LAKE ENHANCED/EFFECT BY FRIDAY NIGHT. WILL GO WITH PARTLY CLOUDY SKIES THROUGH THE WEEKEND...BUT THERE IS SOME CONCERN THAT THERE COULD BE LINGERING LOW CLOUDS BELOW THE STRENGTHENING INVERSION DURING THAT TIME. MAIN QUESTION FOR NEXT WEEK WILL BE THE LOCATION OF A SHORTWAVE CUTTING THROUGH THE UPPER RIDGE OVER THE WESTERN CONUS AND IT/S INFLUENCE ON THE UPPER TROUGH ON THE EAST COAST. 00Z ECMWF HOLDS THE TROUGH OVER THE AREA...WHILE THE GFS TRIES TO PUSH THE RIDGE OVER THE AREA ON MONDAY. THIS HAS THE POTENTIAL FOR WEAKENING THE SURFACE RIDGE AND PUSHING SOME PRECIPITATION INTO THE AREA ON THE EAST SIDE OF A LOW MOVING THROUGH CENTRAL PLAINS OR UPPER MISSISSIPPI VALLEY. WILL RESPECT THE CONSISTENCY SHOWN IN THE ECMWF OVER THE LAST SEVERAL DAYS AND TRY TO KEEP MUCH OF THE AREA DRY. HIGH TEMPERATURES ARE STILL LOOKING TO BE BELOW NORMAL THROUGH THE LONG TERM PERIOD. LOOKING AT THE LONGER RANGE FORECASTS /EVEN THOUGH SKILL IS FAIRLY LIMITED/...NOT TOO MANY SIGNS OF SPRING FOR THE FIRST WEEK OR TWO OF MARCH. GFS/ECMWF ENS MEANS ARE SHOWING 850MB TEMPS BELOW NORMAL THROUGH THE FIRST WEEK AND GFS ENS 500MB MEAN HEIGHTS ARE SHOWING A TROUGH REMAINING OVER THE EASTERN CONUS THROUGH THE MIDDLE OF MARCH. AFTER BEING SPOILED BY WARM MARCH WEATHER IN 2010/2012...ITS LOOKING LIKE MARCH WILL BE MORE TRADITIONAL TEMPERATURE WISE. UNFORTUNATELY FOR SOME OF THE LOCATIONS OF CENTRAL UPPER MICHIGAN THAT HAVE SEEN PROLONGED DRYNESS...THIS PATTERN WON/T BE SUPPORTIVE OF ANY SIGNIFICANT PRECIPITATION AND MAINLY JUST LIGHT PRECIPITATION FROM CLIPPERS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1201 AM EST WED FEB 27 2013 MOIST NE FLOW SHOULD GENERALLY MAINTAIN MVFR CLOUDS THROUGH PD AT ALL TAF SITES. DOWNSLOPING FLOW AT KCMX COULD PERHAPS LEAD TO BRIEF BREAKS IN CLOUDS THERE...BUT OTHERWISE INCREASINGLY MOIST NE FLOW SHOULD ENSURE LOW CLOUDS THROUGH FCST PD. KSAW COULD SEE SOME AFTERNOON FLURRIES FROM DEEPER MOISTURE WRAPPING BACK INTO AREA FROM SYSTEM LIFTING THROUGH LOWER LAKES. TIGHTENING PRES GRAD WILL ALLOW NE WINDS TO GUST NEAR 25 KTS BY LATE WED MORNING/EARLY AFTERNOON...ESPECIALLY AT KSAW && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 428 PM EST TUE FEB 26 2013 TIGHTENING PRES GRADIENT BTWN HIGH PRES TO THE N AND NW AND LOW PRES TRACKING THRU THE LWR OHIO VALLEY TO LWR LAKES WILL RESULT IN NORTHEASTERLY WINDS ACROSS LAKE SUPERIOR INCREASING TO 20-30KT TONIGHT THRU WED. MIGHT SEE A FEW GALE FORCE GUSTS WED AFTN OVER THE E HALF. EVEN THOUGH THE LOW CONTINUES TO MOVE E THU...THE HIGH BUILDING TOWARD THE AREA FROM N WILL MAINTAIN A TIGHT PRES GRADIENT...RESULTING IN CONTINUED 20-30KT WINDS WITH SOME GALE FORCE GUSTS POSSIBLE OVER THE E HALF THRU THU MORNING. WINDS WILL THEN VERY SLOWLY DIMINISH FROM W TO E FRI/SAT AS THE HIGH PRES MOVES CLOSER...BUT IT WILL PROBABLY BE SAT BEFORE WINDS DROP BLO 20KT ACROSS THE ENTIRE LAKE. THE PERIOD OF STRONG WINDS WED NIGHT THRU FRI WILL ALSO BRING THE POTENTIAL FOR FREEZING SPRAY. LIGHT WINDS UNDER 10KT ARE EXPECTED SUN AS SFC HIGH PRES RIDGE WILL EXTEND FROM HUDSON BAY S ACROSS LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...SRF AVIATION...VOSS MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1144 PM CST TUE FEB 26 2013 .AVIATION... /06Z TAF ISSUANCE/ LIFR OR LOWER CONDITIONS SHOULD REMAIN JUST WEST OF KAXN AND KRWF OVERNIGHT AS DRIER AIR LOW LEVEL AIR CONTINUES TO STREAM IN FROM THE NORTHEAST. VISIBILITIES BETWEEN 2 AND 4SM IN BR WILL BE COMMON. MVFR CEILINGS (BKN-OVC020-025) HAVE SPREAD ACROSS KEAU FROM THE EAST AND WILL SOON REACH KRNH AND KMSP BY 09Z. SHORT TERM GUIDANCE SUGGESTS THAT THIS WILL LAST THROUGH THE DAY AND THE UPCOMING NIGHT WITH A SMALL CHANCE FOR VFR LATE WEDNESDAY AFTERNOON AND EARLY EVENING. HOWEVER...CONFIDENCE IS NOT HIGH ENOUGH TO STRAY FROM MVFR ATTM. THERE WILL ALSO BE SOME LIGHT SNOW AT KEAU WEDNESDAY MORNING AND EARLY AFTERNOON. THE BEST PERIOD FOR SMALL ACCUMULATIONS LOOKS TO BE BETWEEN 14Z AND 20Z. SOME SNOW SHOWERS COULD REACH KRNH. ALL SITES EXPECTED TO BE AOB 030 WEDNESDAY NIGHT WITH KAXN AOB 010. NORTHERLY WINDS OVERNIGHT NEAR 10 KNOTS INCREASING TO 12-15 KNOTS WITH GUSTS TO 22-25 KNOTS ON WEDNESDAY. KMSP...MVFR CEILINGS CURRENTLY ABOUT 50 MILES EAST OF THE AIRFIELD. ITS DIFFICULT TO CALCULATE THEIR WESTWARD SPEED DUE TO THE EXTENSIVE HIGH LEVEL OVERCAST ACROSS THE REGION. A ROUGH ESTIMATE IS 25 KTS WHICH WOULD BRING THE CEILINGS IN BEFORE 07Z. CHANCES ARE PRETTY HIGH THAT THE MVFR CEILINGS WILL CONTINUE THROUGH THE TAF PERIOD ALTHOUGH THERE IS A SMALL CHANCE FOR IMPROVEMENT WEDNESDAY AFTERNOON/EVENING AS THE LOW LEVEL NE FLOW OFF OF LAKE SUPERIOR ENDS AND BECOMES MORE NORTHERLY. CHANCES THEN INCREASE AGAIN FOR MVFR CEILINGS OVERNIGHT AND THURSDAY MORNING AS A TROUGH OF LOW PRESSURE DROPS SOUTH ACROSS THE REGION. /OUTLOOK FOR KMSP/ THU...MVFR CIGS. N WIND 10 KTS. FRI...VFR WITH MVFR CIGS POSSIBLE. N WIND 5-10 KTS. SAT...VFR. N WIND 5 KTS. && .DISCUSSION... /ISSUED AT 233 PM CST TUE FEB 26 2013/ INITIAL CONCERN IS CLOUD COVER OVERNIGHT. DRIER WEDGE IN LOWER LEVEL CIRCULATING AROUND STORM TO THE SOUTH WAS STRONG ENOUGH THIS AFTERNOON TO ERODE CLOUDS SOME. ANOTHER SURGE OF MOISTURE APPEARS TO BE WORKING ACROSS THE UP AND NORTHEAST WI AND IS NOW MOVING ACROSS WEST CENTRAL WI. LATEST RAP HAS THIS WORKING SOUTHWEST LATE AFTERNOON INTO THE EVENING...AFFECTING MAINLY SOUTH CENTRAL MN. STRATUS AND FOG IS NOW ERODING FROM THE NORTH AS WELL...IN DRIER AIR FLOW OVER NORTHEAST MN. DIFFICULT TO DISCERN HOW FAR SOUTH AND WEST THIS WILL GO. MODELS TREND MUCH DRIER IN THE 925-850MB LAYER OVER THE WESTERN AREAS. STILL BELIEVE SIGNIFICANT AMOUNT OF MID/HIGH CLOUDS WILL CONTINUE TO STREAM NORTH AND WEST OVER NIGHT AND SHOULD MAINTAIN AT LEAST A MOSTLY CLOUDY SKY OVER MOST OF THE AREA. FOG SHOULD BE LIMITED TO THE FAR WEST INTO THE EVENING...AND SHOULDNT BECOME DENSE OR AS WIDESPREAD WITH THE GRADIENT INCREASING AS WELL AS THE SURFACE WINDS OVERNIGHT. CONCERN NUMBER TWO REMAINS HOW FAR NORTHWEST SNOW WILL DEVELOP MAINLY DURING THE DAY WEDNESDAY. MODELS FAIRLY CONSISTENT ON DRAGGING SNOW INTO FAR SOUTHEAST CWA...WITH THE NAM REMAINING THE DRIEST. THE GFS IS FARTHER WEST INTO OUR CWA...WITH THE 12Z GEM AND ECMWF CONFINING POSSIBILITY TO THE FAR SOUTHEAST CORNER OF THE AREA. IT ALL HINGES ON HOW THE SECONDARY UPPER TROUGH MOVES ACROSS KANSAS AND MERGES WITH THE UPPER LOW MOVING OVER THE OHIO RIVER RIVER VALLEY. WILL CONTINUE THE TREND OF LOW END CHANCE POPS OVER THAT REGION THROUGH WEDNESDAY. SHOULD SEE SOME CLEARING INTO WEDNESDAY NIGHT FOLLOWING THE STORM SYSTEM TO THE SOUTHEAST...BUT MODELS TREND ANOTHER SHORT WAVE DROPPING SOUTHEAST OVER THE DAKOTAS AND MINNESOTA...THURSDAY INTO FRIDAY. THIS SHOULD YIELD AT LEAST MORE CLOUDS AND THE THREAT OF SOME FLURRIES...MAINLY OVER THE WESTERN AREAS. THE 12Z ECMWF IS NOT AS AMPLIFIED WITH THIS FEATURE AND IS A BIT DRIER...SO WILL LEAVE FLURRY MENTION OUT FOR NOW. HIGH TEMPERATURES FORECAST SLIGHTLY BELOW NORMAL INTO THE WEEKEND. NEXT STRONG TROUGH MOVES ASHORE ON THE WEST COAST OVER THE WEEKEND. LONGER TERM MODELS BRINGING THIS NEXT WAVE/TROUGH INTO THE AREA MAINLY SUNDAY NIGHT INTO TUESDAY. HAVE INCLUDED SMALL CHANCE POPS FOR THIS FEATURE AS IT MOVES THROUGH THE AREA FOR NOW. COULD BE WARM ENOUGH FOR A POSSIBLY MIX AS THE SYSTEM WORKS INTO THE AREA...AT LEAST INITIALLY. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ RAH/DWE
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AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1102 PM CST TUE FEB 26 2013 .UPDATE... ADDED FOND DU LAC AND WASHINGTON COUNTIES TO WARNING AS PERSISTENT SNOW BAND LINGERS WITH CALLS TO THE SHERIFF DEPARTMENTS INDICATING THE FALLING SNOW AND GUSTY WINDS WERE MAKING ROADS NEARLY IMPASSIBLE IN EASTERN FOND DU LAC COUNTY AND NORTHERN WASHINGTON. HEAVIER SNOW BANDS NOT MAKING A LOT OF PROGRESS TO THE WEST AS DRIER AIR...MARKED BY LOWER DEW POINTS...IS NOSING INTO NW PORTIONS OF THE FORECAST AREA. ALSO WATCHING THE FIRST OF NUMEROUS SNOW SHOWERS MOVING ONSHORE OVER EXTREME NE IL/SE WI. WAUKEGAN IL DOWN TO 3/4 MILE...OR 1/2 INCH/HOUR SNOW RATE...WITH THIS LEAD SNOW SHOWER BAND. && .AVIATION/06Z TAFS/... WILL LIKELY KEEP TAF SITES AT IFR LEVELS...ESPECIALLY CIGS...THROUGH THE FORECAST PERIOD ...THOUGH GFS GUIDANCE INDICATES KMSN MAY IMPROVE TO MVFR EARLY WEDNESDAY EVENING IN SUBSIDENCE BEHIND SPOKE OF VORTICITY ROTATING AROUND UPPER LOW. EXPECT STEADY ACCUMULATING SNOW TO BECOME MORE OCCASIONAL THROUGH THE OVERNIGHT AS FORM OF PRECIPITATION TURNS TO SNOW SHOWERS...WITH BREAKS BETWEEN CELLS. NORTHEAST WINDS WILL TURN NORTH BUT REMAIN GUSTY...WITH THE STRONGEST WINDS AT KMKE AND KENW...EASING SLOWLY TO THE WEST AT KUES AND KMSN. && .MARINE... WILL BE EXTENDING GALE WARNING UNTIL 09Z AS BOTH RAP AND NAM SOUNDINGS TAP 37 KNOT+ WINDS UNTIL AT LEAST 08Z. NOT SEEING GALE GUSTS AT SOUTHERN LOCATIONS AT THIS TIME...BUT GRADIENT WILL TIGHTEN FOR A TIME AS LOW LIFTS TOWARD SRN LOWER MICHIGAN AND WINDS BECOME NORTH. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...WINTER STORM WARNING UNTIL NOON CST WEDNESDAY FOR WIZ051-052-059- 060-066-070>072. WINTER WEATHER ADVISORY UNTIL NOON CST WEDNESDAY FOR WIZ058- 062>065-067>069. LM...GALE WARNING UNTIL 3 AM CST WEDNESDAY FOR LMZ643>646. && $$ UPDATE...REM TONIGHT/WEDNESDAY AND AVIATION/MARINE...MEB WEDNESDAY NIGHT THROUGH TUESDAY...DAVIS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
324 AM MST WED FEB 27 2013 .SHORT TERM...VALID FOR TDY AND THU... A COUPLE OF DYNAMICALLY-WEAK AND MOISTURE-STARVED WAVES ARE HEADED OUR WAY THE NEXT TWO DAYS...BUT IMPACTS WITH THEM APPEAR MINIMAL. TODAY...STRATUS BUILT SOUTHEAST INTO MILES CITY AND BAKER BEHIND A WEAK COLD FRONT OVERNIGHT...SO A PRIMARY FORECAST CONSIDERATION IS WHEN IT WILL BREAK UP. RAP-BASED SOLUTIONS HOLD THE STRATUS ACROSS MUCH OF SOUTHEASTERN MT THROUGH THE DAY...WHICH KEEPS HIGHS IN THE LOWER 30S F EVEN FOR MILES CITY IN THOSE MODEL SIMULATIONS. HAVING SAID THAT...THE PLANETARY BOUNDARY LAYER PARAMETERIZATION THAT THE RAP USES IS KNOWN TO BE TOO SLOW IN ERODING STRATUS...SO THAT IDEA IS PROBABLY THE WORST-CASE SCENARIO. RECENT HRRR RUNS SEEM TO HAVE A BETTER HANDLE ON THE STRATUS...TAKING IT OUT OF MILES CITY PRIOR TO 18 UTC...AND LINGERING IT INTO THE AFTERNOON ONLY AROUND BAKER. WE THUS REDUCED HIGHS INTO THE MID 30S F AT BAKER...BUT DECIDED TO LEAVE THEM ALONE OVER THE REST OF SOUTHEASTERN MT. HIGHS OVER MOST OF THE AREA ARE IN LINE WITH THE 00 UTC BIAS-CORRECTED MULTI-MODEL CONSENSUS...WHICH SUPPORTS READINGS OF 40 TO 45 F AGAIN TODAY WITH BARE GROUND HELPING OUT WARMING DESPITE MODEST MIXING. TONIGHT...A WEAK 500-HPA SHORT WAVE TROUGH WILL CROSS THE AREA. WE LEFT LOW-END POPS IN PLAY FOR CONTINUITY/S SAKE AND OUT OF RESPECT TO THE 00 UTC GFS...WHICH DOES SIMULATE SOME SHOWERS. THE GFS IDEA IS ADMITTEDLY A BIT OF AN OUTLIER THOUGH. OTHERWISE...WINDS SHOULD INCREASE AT BOTH LIVINGSTON AND BIG TIMBER AS THE SURFACE GRADIENT TIGHTENS WITH THE PASSAGE OF THE SHORT WAVE. IF THE GFS DOES PROVE CORRECT...WE MAY ACTUALLY NEED TO FURTHER INCREASE WIND SPEEDS FOR BIG TIMBER. FORECAST LOWS TONIGHT ARE BASED ALMOST ENTIRELY ON THE 00 UTC BIAS-CORRECTED GFS GRIDDED MOS OUTPUT...WHICH HAS PERFORMED MUCH BETTER THAN MOST COLD-BIASED LOW TEMPERATURE GUIDANCE LATELY. THU...WEAK COLD AIR ADVECTION ALOFT WILL YIELD MIXING UP TO AROUND 750 HPA IN MOST AREAS...WHICH WILL COMBINE WITH DOWNSLOPE WINDS IN THE BOUNDARY LAYER TO PROMOTE ANOTHER SEASONABLY MILD DAY. THE GFS AND WRF-BASED SOLUTIONS LIKE THE NAM AND SREF ARE AT ODDS WITH THE NEXT WEAK 500-HPA SHORT WAVE...WITH THE LATTER MODELS SUPPORTING A LOW-END SHOWER CHANCE AGAIN...ESPECIALLY BY THU EVENING. GIVEN THE MODEL SPREAD...WE CHOSE TO LEAVE OUR MAINLY DRY FORECAST ALONE FOR NOW. THAT ALSO SERVES TO LIMIT THE NUMBER OF PERIODS CONTAINING 20 OR 30 PERCENT POPS IN WHAT IS GENERALLY A BENIGN PATTERN. SCHULTZ .LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE... MODELS HAVING TROUBLE RESOLVING SMALLER FEATURES THROUGH THE EXTENDED SO HAVE KEPT A BROADBRUSH APPROACH GOING WITH THIS PACKAGE. MODELS ARE IN AGREEMENT WITH STRONG UPPER RIDGE DEVELOPING FOR LATE THURSDAY INTO SUNDAY. DEEP TROF IN THE EASTERN U.S. WILL BLOCK FLOW ACROSS THE REGION...ESPECIALLY THE NORTHERN JET STREAM...RESULTING IN RIDGE DEVELOPMENT OVER THE AREA LATE WEEK INTO THE WEEKEND. 850 TEMPERATURES PUSH DOUBLE DIGITS BY FRIDAY INTO SATURDAY FOR HIGHS IN THE 50S TO LOWER 60S. THERE IS A GOOD MOISTURE STREAM OVER RIDING THE RIDGE SO EXPECT A GOOD DEAL OF MID AND HIGH CLOUD COVER AND A FEW SNOW SHOWERS FOR MOUNTAIN AREAS. MODEL SPECTRUM DOES SHOW A VERY LARGE SPREAD FOR TEMPERATURES FRIDAY INTO SATURDAY DUE TO A FEW MODEL SOLUTIONS HOLDING ONTO COLDER SOLUTION FROM THE PAST FEW DAYS. LATEST RUNS SEEM SOLIDLY IN THE WARM SIDE OF GUIDANCE AND RECENT MODEL SOLUTIONS HAVE TRENDED TOO COLD BY 5 TO 10 DEGREES THUS PUSHED CURRENT FORECAST TOWARD THE HIGH END OF GUIDANCE. SUNDAY INTO WEDNESDAY LOOKS UNSETTLED AS SEVERAL PACIFIC SYSTEMS TRY TO BUILD INTO THE AREA. BLOCKING BY DEEP TROF OVER THE EASTERN U.S. WILL CONTINUE TO PRESENT A PROBLEM FOR EASTERLY MOVEMENT AND HAVE SEEN MODELS JUMP AROUND FROM SOLUTIONS THAT SIT THESE PACIFIC DISTURBANCES OVER THE AREA FOR A DAY OR TWO TO OTHER SOLUTIONS THAT MOVE SYSTEMS IN FROM THE WEST THEN DEFLECT THEM SOUTHWARD INTO WYOMING AND COLORADO. MODELS BRING THE FIRST OF THE SYSTEMS INTO THE AREA SUNDAY AFTERNOON...BUT THIS MAY BE A BIT FAST GIVEN UPSTREAM BLOCK. KEPT TEMPERATURES ON THE WARM END SUNDAY BUT DID ADD MENTION OF CHANCE POPS TO WESTERN HALF OF FORECAST AREA. MONDAY INTO WEDNESDAY LOOK UNSETTLED WITH BROADBRUSH 30 AND 40 POPS FOR LOWER ELEVATIONS AND LIKELY POPS FOR THE MOUNTAINS ON MONDAY...AND CLIMO TYPE POPS AND TEMPERATURES FOR TUESDAY INTO WEDNESDAY BASED ON MODEL INCONSISTENCY. CHAMBERS && .AVIATION... MVFR CEILINGS WILL PERSIST THIS MORNING EAST OF ROSEBUD COUNTY INCLUDING KMLS AND KBHK...SLOWLY CLEARING FROM WEST TO EAST THIS AFTERNOON. OTHERWISE VFR CONDITIONS WILL PREVAIL TODAY. A WEAK DISTURBANCE WILL BRING ISOLATED RAIN/SNOW SHOWERS TO THE AREA THIS AFTERNOON INTO TONIGHT. CHAMBERS && .PRELIMINARY POINT TEMP/POPS... TDY THU FRI SAT SUN MON TUE ------------------------------------------------------- BIL 043 027/044 028/051 036/058 039/046 037/040 025/043 0/B 21/B 11/B 00/U 12/W 53/J 11/B LVM 039 024/040 028/044 032/052 035/043 031/036 022/041 1/N 22/W 12/J 00/B 14/W 43/J 22/J HDN 042 024/042 024/048 032/056 036/052 038/039 026/042 0/U 21/B 10/B 00/U 12/W 54/J 11/B MLS 044 028/046 030/049 036/056 038/055 038/038 028/041 1/B 21/B 10/B 00/B 11/B 44/J 21/E 4BQ 040 023/040 026/046 034/054 035/052 037/038 027/041 0/B 22/J 10/B 00/B 02/W 44/J 31/E BHK 034 023/039 024/044 033/051 036/050 033/034 025/035 1/E 12/W 11/B 00/B 01/B 44/J 31/E SHR 036 013/037 018/042 028/052 029/051 026/035 020/039 0/U 11/B 11/B 10/U 02/W 53/J 21/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
530 AM CST WED FEB 27 2013 .DISCUSSION.../ISSUED AT 308 AM CST/ A MOSTLY CLOUDY AND BREEZY DAY IS IN STORE FOR THE AREA. LOW CLOUDS SEEM TO BE BREAKING UP OVER MUCH OF THE AREA...BUT MID AND HIGH CLOUDS WILL REMAIN ABUNDANT. NORTHWESTERLY WINDS WILL INCREASE THROUGH THE DAY...WITH GUSTS AROUND 30 MPH THIS AFTERNOON. STRONGEST WINDS ARE ANTICIPATED ALONG THE MISSOURI RIVER...AND ACROSS PORTIONS OF NORTHWEST IOWA AND SOUTHWEST MINNESOTA...WHERE WE COULD SEE GUSTS UP TO 35 MPH. HIGHS WILL CONTINUE TO RUN A FEW DEGREES BELOW NORMAL...WITH READINGS MAINLY IN THE LOW TO MID 30S. LOOKS LIKE STRATUS WILL MOVE BACK INTO THE AREA LATER TODAY INTO TONIGHT FROM NORTHWEST TO SOUTHEAST IN A WEAK COLD AIR ADVECTION REGIME. THESE CLOUDS AND A CONTINUED NORTHERLY BREEZE SHOULD KEEP LOWS IN THE LOW 20S. LOW LEVEL MOISTURE EVENTUALLY BECOMES PRETTY DEEP BY LATER TONIGHT INTO THURSDAY MORNING...SUGGESTING WE COULD END UP SEEING SOME SCATTERED FLURRIES FROM THE LOW CLOUDS. AREA OF UPPER LEVEL DIVQ IS ALSO OVERHEAD THURSDAY...BUT ENOUGH MID LEVEL DRY AIR EXISTS...THAT FEEL ANY FLURRIES THAT DO FALL WILL BE LOW STRATUS BASED...AND NOT FROM THE UPPER LEVEL FORCING...AND THE BEST THREAT OF THIS WILL PROBABLY BE ALONG AND NORTH OF INTERSTATE 90. HIGHS THURSDAY LIKELY A BIT COOLER THAN TODAY...MAINLY UPPER 20S TO LOW 30S. SOME SIGNS THAT WE SEE A FRONTAL BAND OF SNOW ON THURSDAY NIGHT INTO FRIDAY MORNING AS A WAVE AND SURFACE LOW DROPS SOUTHEAST. NAM IS MOST AGGRESSIVE WITH THIS FEATURE...BUT THE GFS...SREF AND ECMWF ALL HINTING AT SOMETHING. THUS WILL ADD IN A SLIGHT CHANCE OF SNOW WEST OF THE JAMES RIVER...WHERE BEST THREAT APPEARS TO BE. OTHERWISE MUCH OF THE SAME FRIDAY...WITH PARTLY TO MOSTLY CLOUDY SKIES AND HIGHS IN THE MID 20S TO LOWER 30S. WEST COAST RIDGE TRIES TO BUILD EAST OVER THE WEEKEND. QUITE THE DIFFERENCE BETWEEN THE GFS AND ECMWF ON HOW FAR EAST THE RIDGE BUILDS...WITH AROUND A 10C DIFFERENCE IN MODEL 850MB TEMPERATURES...ECMWF BEING WARMER. GEM SEEMS TO BE BETWEEN THE TWO...AND THUS WILL CONTINUE WITH VALUES CLOSE TO CONSENSUS THROUGH THE WEEKEND. EVEN IF THE WARMER ECMWF VERIFIES...WARMING WILL LIKELY BE TEMPERED BY SNOW COVER AND CLOUDINESS. FOR NOW HIGHS IN THE 20S EAST TO 40S WEST SEEM MOST LIKELY. ATTENTION WILL THEN TURN TO A WAVE COMING ASHORE ALONG THE PACIFIC NORTHWEST COAST...WHICH WILL DIVE SOUTHEAST INTO THE PLAINS MONDAY INTO MONDAY NIGHT. ECMWF AND GEM A BIT STRONGER WITH THIS WAVE AND THUS A LITTLE FURTHER SOUTH. WILL HAVE TO CONTINUE TO MONITOR TRENDS...BUT AT THIS TIME FAVOR A SOLUTION CLOSER TO THE GEM AND ECMWF. THIS SYSTEM DOES HAVE SOME DECENT MOISTURE TO WORK WITH...SO WHILE NOT EXPECTING ANYTHING TOO SIGNIFICANT...THINK AN AREA OF ACCUMULATING SNOW IS PROBABLE TO THE NORTH OF THE LOW TRACK. IN FACT THE ECMWF SHOWS A LARGE SWATH OF 0.4 TO 0.7 INCHES OF QPF IN A BAND NORTH OF THE LOW TRACK. EVEN IF THIS IS OVERDONE...WOULD EXPECT AT LEAST LIGHT SNOW ACCUMULATIONS...WITH POTENTIALLY A NARROWER AREA OF MORE MODERATE AMOUNTS. AGAIN WHERE THIS OCCURS IS STILL UNCERTAIN...AND IF THE SOUTHWARD TREND ON THE ECMWF WERE TO CONTINUE...MOST OF THE SNOW COULD EVEN END UP SOUTHWEST OF OUR CWA. EITHER WAY SOMETHING TO WATCH OVER THE COMING DAYS. PRECIP TYPE MAY INITIALLY BE RAIN OR SNOW...BUT WITH THE SOUTHWARD TREND...EXPECTING MAINLY SNOW WITH ANYTHING THAT ENDS UP FALLING. TEMPERATURES SHOULD STAY A LITTLE BELOW NORMAL BEHIND THIS SYSTEM INTO EARLY NEXT WEEK. /CHENARD && .AVIATION.../FOR THE 12Z TAF ISSUANCE/ THE SIOUX FALLS FORECAST AREA HAS NOW LOST ALL STRATUS EXCEPT FOR A NARROW STRIPE OF IFR EXTENDING FROM KYKN TO KSUX. THE STRATUS IN THIS AREA CONTINUES TO BE OBSCURED ON THE IR SATELLITE BY ABUNDANT HIGH LEVEL CLOUDINESS. BUT WITH LOW LEVEL WINDS FROM THE NORTH AND NORTHWEST...IT IS LIKELY THAT DRIER AIR WILL ALSO ENTRAIN INTO THESE AREAS SHORTLY...AND THUS GIVE THE KSUX TAF SITE VFR CONDITIONS BY EARLY THIS MORNING. TO THE WEST OF OUR FORECAST AREA...PLENTY OF MVFR STRATUS EXISTS IN CENTRAL SD AND ND. EVENTUALLY...THIS STRATUS WILL BEGIN TO MOVE INTO OUR WESTERN ZONES. BUT IT MAY TAKE AWHILE AS WINDS AT 925MB WILL REMAIN DUE NORTHERLY THROUGH THE MORNING HOURS IN OUR FORECAST AREA. BOTH THE NAM12 AND RAP MODELS STRONGLY SUGGEST THAT THE MVFR CEILINGS WILL NOT GET INTO THE KHON TAF SITE UNTIL ABOUT 20Z. THIS AFTERNOON...THE 925MB WINDS DO INDEED BECOME MORE NORTHWESTERLY AS OPPOSED TO NORTH...SO THIS MAKES SENSE AT THIS TIME. EXTRAPOLATING THE STRATUS FURTHER EASTWARD...GIVES AN MVFR ARRIVAL OF AROUND 00Z/28 FOR KFSD...AND ABOUT 02Z/28 FOR KSUX. LASTLY...NORTHWEST SURFACE WINDS WILL BE RATHER BREEZY IN THE LATE MORNING AND AFTERNOON AT 15 TO 25 KNOTS EAST OF THE JAMES RIVER VALLEY. HOWEVER DUE TO A WELL MIXED DAY TODAY...THERE WILL LIKELY NOT BE ANY VISIBILITY RESTRICTIONS TONIGHT BELOW THE VFR OR MVFR CATEGORY. /MJF && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1006 AM MST WED FEB 27 2013 .UPDATE... && .SHORT TERM...CURRENT FORECASTS LOOK ON TRACK. NORTHERLY FLOW FINALLY WEAKENING ACROSS THE PLAINS WITH SURFACE OBS SHOWING WINDS DECREASING THOUGH STILL SOME GUSTS AROUND 25 KTS. COULD REMAIN A BIT GUSTY FAR EASTERN ZONES THROUGH THE AFTERNOON AS MODELS STILL SHOW A NORTHERLY GRADIENT. SOME MOISTURE STILL TRAPPED ACROSS THE MOUNTAINS...WITH WEB CAMS SHOWING SOME LIGHT SNOW ALONG THE RIDGES OF SUMMIT AND GRAND COUNTIES. COULD ALSO BE SOME LIGHT SNOW OVER THE PARK AND GORE RANGES OF JACKSON COUNTY. LATEST RAP CROSS SECTIONS MAINTAIN SOME MOISTURE THERE THROUGH THE AFTERNOON ALONG WITH MODEST LAPSE RATES AND OROGRAPHICS. WILL KEEP SOME LIGHT SNOW THERE THROUGH THE DAY. ANY ACCUMULATIONS TO BE MINIMAL. SLIGHT WARMING EXPECTED TODAY WITH GOOD SUNSHINE...THOUGH RECENT SNOWFALL WILL SLOW PROGRESS. .AVIATION...SKIES HAVE CLEARED ACROSS THE AREA AIRPORTS AS DRIER AIR HAS SPREAD OVER THE REGION. LATEST MODELS SHOWING WINDS SHIFTING TO THE NORTHWEST AROUND 18 OR 19Z WITH SPEEDS AROUND 8 KTS...THEN WEAKENING AROUND 21Z AND A BIT MORE NORTHERLY. RAP AND HRRR SUGGESTING NORTHEAST TO EAST WINDS AFTER 21Z WITH THE DEVELOPMENT OF A WEAK ANTICYCLONE. WITH NORTHWEST FLOW ALOFT... UNSURE ABOUT THE ANTICYCLONE DEVELOPING AND WILL MAINTAIN THE CURRENT TAF TRENDS. && .PREV DISCUSSION... /ISSUED 444 AM MST WED FEB 27 2013/ UPDATE... SHORT TERM...UPDATED TO REMOVE THE EXPIRATION OF THE ADVISORY FROM PORTIONS OF THE PLAINS. 88D SHOWING LIGHT ECHOES RAPIDLY DIMINISHING. PREV DISCUSSION... /ISSUED 309 AM MST WED FEB 27 2013/ SHORT TERM...THE AREA OF SNOW ACROSS THE NORTHEAST PLAINS IS EVER SO SLOWLY BEGINNING TO SHRINK IN COVERAGE. EARLIER HAD EXTENDED THE ADVISORY UNTIL 4 AM AND THINK THAT SHOULD BE FINE. THERE STILL MAY BE SOME AREAS OF VERY LIGHT SNOW THROUGH THE EARLY MORNING HOURS BUT ANY ADDITIONAL ACCUMULATION WILL BE UNDER A HALF INCH. THERE ARE STILL SOME GUSTY WINDS ON THE PLAINS BUT THESE WINDS WILL ALSO DECREASE THIS MORNING AS THE SURFACE GRADIENT RELAXES. STILL QUITE A BIT OF CLOUD COVER UPSTREAM SO HAVE DELAYED SOME OF THE CLEARING THIS MORNING. A SLOW MODERATION OF TEMPERATURES THIS AFTERNOON WITH MOSTLY SUNNY SKIES. FOR TONIGHT...WILL SOME INCREASING MID AND HIGH LEVEL CLOUDS IN ADVANCE OF NEXT SYSTEM. LONG TERM...YET ANOTHER DISTURBANCE IN THE NORTHWEST FLOW ALOFT WILL SWING DOWN OVER NORTHEAST COLORADO THURSDAY INTO FRIDAY. THIS SYSTEM SHOULD MAINLY AFFECT THE MOUNTAINS IN THE FAVORED FLOW...HOWEVER SOME MODELS ARE PICKING UP ON A POSSIBILITY OF A FEW SHOWERS MOVING OVER THE PLAINS. OVERALL...MODEL AGREEMENT IS POOR ON THE UPPER LEVELS OF THIS DISTURBANCE...AND NORTHWEST FLOW IS USUALLY MORE OF A DOWNSLOPE PATTERN FOR THE PLAINS. HOWEVER CANNOT IGNORE ABOUT HALF OF THE MODELS VIEWED SHOWING LIGHT PRECIPITATION. RUN TO RUN CONSISTENCY IS NOT THE BEST WITH THIS PIECE OF ENERGY...WITH TIMING DIFFERENCES WITH EACH NEW RUN. THE BEST TIME FRAME HOWEVER LOOKS TO BE THURSDAY EVENING FOR A FEW SHOWERS OVER THE PLAINS. OTHERWISE...SNOW WILL BE INCREASING OVER THE MOUNTAINS THROUGH THE DAY THURSDAY AND INTO THE NIGHT...BEFORE EASING OFF FRIDAY. ACCUMULATIONS OVER THE MOUNTAINS WILL MAINLY BE OROGRAPHICALLY DRIVEN...LEAVING THE HIGHEST AMOUNTS ON WEST TO NORTHWEST FACING SLOPES. CURRENTLY EXPECT 3 TO 6 INCHES THURSDAY THROUGH FRIDAY AFTERNOON. THURSDAY TEMPERATURES WILL BE SIMILAR TO TODAYS WITH ONLY A DEGREE OR TWO OF WARMING. FRIDAY WILL SEE TEMPERATURES WARM EVEN MORE WITH THE PLAINS FINALLY REACHING INTO THE LOW 40S AND THE MOUNTAINS IN THE 20S. NORTHWESTERLY SURFACE WINDS WILL BE INCREASING THURSDAY AND INTO FRIDAY AS A 115 KT N TO S JET MOVES OVERHEAD AND AIDED BY SURFACE PRESSURE GRADIENT FROM HIGH PRESSURE OVER SW WYOMING AND LOWER PRESSURE OVER TEXAS. NO HIGHLIGHTS ARE NEEDED. GUSTS MAY REACH 40 TO 50 MPH IN THE FOOTHILLS AND UP TO 30 MPH OVER THE PLAINS THURSDAY NIGHT INTO FRIDAY. FRIDAY NIGHT INTO SUNDAY AFTERNOON...AN UPPER RIDGE BUILDS OVERHEAD TO BRING WARMER AND DRIER CONDITIONS. TEMPERATURES ARE EXPECTED TO RETURN TO NEAR NORMAL READINGS WITH UPPER 40S TO LOW 50S FOR THE PLAINS AND 30S TO LOW 40S FOR THE MOUNTAINS. SUNDAY NIGHT AND INTO MONDAY IS THE NEXT CHANCE FOR MORE PRECIPITATION FOR THE FORECAST AREA. MODELS SHOWING A PACIFIC NORTHWEST SYSTEM DIGGING SOUTHEAST TOWARD THE AREA SUNDAY NIGHT...HOWEVER WITH A DEEPER AND SLOWER SOLUTION SHOWN BY THE ECMWF AND A WEAKER AND MORE PROGRESSIVE SOLUTION BY THE GFS...AND AN EVEN MORE PROGRESSIVE SOLUTION BY THE CANADIAN MODEL. WILL KEEP THE CHANCE OF SNOW FOR THE MOUNTAINS SUNDAY NIGHT INTO MONDAY AND PUT A SLIGHT CHANCE FOR THE PLAINS SUNDAY NIGHT AS MODELS SHOWING SOME SORT OF COLD FRONT MARCHING DOWN THEN. THEN YET ANOTHER UPPER RIDGE WILL BUILD IN MONDAY EVENING INTO WEDNESDAY FOR ANOTHER WARMING AND DRYING TREND. AVIATION...MID LEVEL DECK OF CLOUDS IN THE 6000 TO 8000 FT AGL LEVEL WILL HANG THRU MID MORNING GIVEN THE OBSERVATIONS TO THE NORTHWEST ACROSS WYOMING. SKIES WILL BECOME MOSTLY SUNNY THIS AFTERNOON. NORTH TO NORTHWEST SURFACE WINDS WILL PERSIST THIS MORNING BUT SPEEDS GENERALLY UNDER 15KT. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....KRIEDERMAN AVIATION...D-L
AREA FORECAST DISCUSSION
NWS JACKSON KY
124 PM EST WED FEB 27 2013 .UPDATE... ISSUED AT 124 PM EST WED FEB 27 2013 UPDATED TEMPS FOR THIS AFTERNOON AND EVENING BASED ON CURRENT OBS AND THE HRRR MODEL. ALSO ADJUST PRECIP TYPE BASED ON THIS TONIGHT. THE IMPACT ON THE OVERALL FORECAST IS NEGLIGIBLE. UPDATE ISSUED AT 1007 AM EST WED FEB 27 2013 BASED ON RADAR TRENDS AND FORECAST SOUNDINGS...HAVE ADDED MORE RAIN AND DRIZZLE TO THE FORECAST FOR TODAY...BUT ALL POPS ARE IN THE 20-30 PERCENT RANGE. UPDATE ISSUED AT 627 AM EST WED FEB 27 2013 PRECIPITATION HAS TAPERED TO PRETTY MUCH JUST DRIZZLE AS THE COOLER CLOUD TOPS HAVE EXITED. RUC/NAM BUFR SOUNDINGS CONTINUE TO SHOW A LITTLE BIT OF MOISTURE ABOVE THE LOW LEVEL INVERSION SUPPORTING DRIZZLE THROUGH MID MORNING. HOWEVER...SOME WEAK MID LEVEL SUBSIDENCE WILL ESSENTIALLY TAKE ITS TOLL ON THIS SHALLOW MOISTURE BY LATE THIS MORNING...LEAVING BEHIND GENERALLY OVERCAST SKIES. THE DRY CONDITIONS ARE STILL EXPECTED TO PERSIST THROUGH THE AFTERNOON AND LIKELY INTO THE EARLY EVENING HOURS. RAP/HRRR ALONG WITH SUPPORT FROM THE NAM HAS RAIN SPREADING BACK INTO THE AREA TOWARDS 00Z TONIGHT. RAP/NAM STILL STRONGLY SUPPORT MAINLY RAIN AT THE ONSET AS SURFACE TEMPERATURES REMAIN TOO WARM FOR SNOW. HOWEVER...AS PRECIPITATION INTENSITY INCREASES...WE SHOULD WETBULB DOWN CLOSER TO FREEZING FAIRLY QUICKLY CHANGING ANY RAIN OVER TO SNOW BY LATE EVENING. ALL OF THIS IS STILL IN LINE WITH THE LATEST FORECAST AND SEE NO REASON TO MAKE ANY SIGNIFICANT CHANGES AT THIS TIME. && .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 306 AM EST WED FEB 27 2013 AN UPPER LEVEL LOW WILL CONTINUE TO DRIFT EASTWARD ACROSS THE OHIO RIVER VALLEY OVER THE NEXT 36 TO 48 HOURS. THIS WILL PROVIDE SEVERAL ROUNDS OF UNSETTLED WEATHER THROUGH THE REMAINDER OF THE WEEK. ONGOING LIGHT RAIN/DRIZZLE WILL CONTINUE TO PUSH NORTH AND EAST THROUGH DAYBREAK. MODEL SOUNDINGS SHOW ICE ACTIVATION DWINDLING TOWARDS DAYBREAK AS THE BETTER MOISTURE LIFTS TO THE NORTH AND EAST. THIS WILL LIKELY PROVIDE A PERIOD OF DRIER WEATHER FROM THIS MORNING INTO THEA AFTERNOON HOURS. HOWEVER...A VIGOROUS TROUGH WILL PUSH SOUTH INTO EASTERN KENTUCKY LATE IN THE DAY AND TONIGHT...PRODUCING A PERIOD OF RAIN...POSSIBLY MIXED WITH A LITTLE SNOW THIS EVENING. AS TEMPERATURES QUICKLY COOL THIS EVENING...RAIN SHOULD QUICKLY TRANSITION TO SNOW ON THE RIDGES WITH THE VALLEYS FOLLOWING A FEW HOURS LATER. LOCATIONS ABOVE 1500 FEET WILL LIKELY BE ALL SNOW FROM THE ONSET...AND WITH TEMPERATURES VERY COOL AT THESE HIGHER ELEVATIONS...THE LARGEST SNOW ACCUMULATIONS WILL LIKELY FALL ABOVE 1500 FEET. UP TO 3 OR 4 INCHES MAY BE POSSIBLE ABOVE 2000 FEET. HOWEVER...ALL RIDGES WILL LIKELY SEE SOME MINOR SNOW ACCUMULATIONS (UNDER A HALF INCH) WITH THE VALLEYS STRUGGLING TO SEE ANY ACCUMULATION. THE FAVORED UPSLOPE AREAS WILL BE FAVORED WITH THE MOST SNOW POTENTIAL INTO THURSDAY. SURFACE TEMPERATURES WILL CLIMB INTO THE MID TO UPPER 30S ON THURSDAY WITH SNOW ACCUMULATIONS NOT MUCH OF A THREAT DURING THE DAY. IN FACT...WE MAY CHANGEOVER TO RAIN IN SEVERAL AREAS. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 355 AM EST WED FEB 27 2013 THE MODELS CONTINUE IN FAIR AGREEMENT ALOFT FOR THE LONG TERM PORTION OF THE FORECAST. THEY ALL TAKE A CLOSED LOW EAST OUT OF THE REGION ON THURSDAY NIGHT LEAVING BEHIND JUST A GENERAL AREA OF LOW HEIGHTS. PLENTY OF ENERGY WILL ALSO BE STUCK BACK HERE THROUGH THE SOUTHERN PLAINS AND TENNESSEE VALLEY. THIS COLLECTION WILL START TO CONSOLIDATE ON FRIDAY TO FORM A NEW SEMI-CLOSED LOW OVER THE REGION...PRIMARILY IN RESPONSE TO A STRONG RIDGE BUILDING OVER THE WEST. THE DEVELOPING LOW WILL SWIRL PLENTY OF SHORTWAVE ENERGY...THOUGH GENERALLY WEAK...THROUGH THE AREA INTO SATURDAY MAINTAINING UNSETTLED WEATHER. THE GFS FORMS ITS UPPER LOW A BIT QUICKER THAN THE GEM AND ECMWF...MAINTAINING A STRONGER SOLUTION THROUGH THE WEEKEND. GIVEN THE MODEL TRENDS WILL FAVOR A WEAKER VERSION OF THE GFS...BUT DO LIKE ITS MORE PROGRESSIVE SOLUTION. THE UPPER LOW WILL BECOME MORE OF A DEEP TROUGH THROUGH THE EASTERN HALF OF THE NATION BY SUNDAY MORNING AND GET SHOVED EAST BY THE STRONG WESTERN RIDGING. CONTINUING WITH THE CONSENSUS SOLUTION...HEIGHTS WILL RISE OVER THE AREA LATER SUNDAY AND CERTAINLY INTO MONDAY AS ENERGY TOPS THE RIDGE AND SLIDES BY JUST TO OUR EAST. HOWEVER...THE PATTERN BECOMES MORE MUDDLED HEADING INTO THE MIDDLE OF NEXT WEEK AS THE WESTERN RIDGE IS BASICALLY WIPED OUT BY ENERGY MOVING INTO THE PLAINS AND IT SLINKS THROUGH THE AREA AS JUST A WEAK AND SHORT LIVED RISE IN HEIGHTS MONDAY NIGHT. BY TUESDAY...THE ENERGY FROM THE RIDGE KILLING WAVE WILL REACH THE MID SECTION OF THE NATION AND START TO IMPACT THE OHIO VALLEY. SENSIBLE WEATHER WILL FEATURE A CHILLY PATTERN WITH SEVERAL REINFORCING SHOTS OF COLD AIR THROUGH THE WEEKEND. THE FIRST PART OF THE EXTENDED WILL SEE SNOW SHOWERS ACCOMPANY THE COLDER AIR. HOWEVER...DEEP LAYER MOISTURE AND UPPER LEVEL SUPPORT WILL BE LIMITED FOR MUCH OF THIS TIME. ACCORDINGLY...THE ACCUMULATIONS ARE EXPECTED TO BE LIGHT AND MAINLY CONFINED TO THE NIGHT TIME HOURS. THE HIGHER TERRAIN IN THE FAR SOUTHEAST PARTS OF THE CWA WILL SEE THE BEST CHANCE FOR ANY ACCUMULATION MEASURED IN MULTIPLE INCHES...WHILE THE REST OF THE AREA WILL LIKELY END UP WITH LESS THAN AN INCH. THE BEST SHOT AT SEEING LIGHT ACCUMULATIONS...EVEN IN THE VALLEYS...WILL BE THURSDAY NIGHT GIVEN A COLDER AIR MASS. CERTAINLY ANY HEAVIER BURST OF SNOW OR BANDING COULD LEAD TO BRIEF ACCUMULATIONS DURING THE DAYLIGHT HOURS...BUT THESE ARE LIKELY TO BE THE EXCEPTION RATHER THAN THE RULE THROUGHOUT THE PERIOD. THE REAL PROBLEM IS THE LACK OF A SOLID SFC WAVE TO GEN UP THE PCPN THAT COULD TAKE ADVANTAGE OF THE COLD AIR AND GIVE MORE THAN OCCASIONAL SKIFFS OF ACCUMULATION. LINGERING SNOW SHOWERS THROUGH THE DAY SATURDAY AND INTO SUNDAY IN THE FAR SOUTHEAST WILL KEEP THE POTENTIAL FOR SOME ADDITIONAL ACCUMULATIONS IN THE FORECAST WITH THE HIGHER TERRAIN FAVORED...BUT CHILLY TEMPS EVEN DURING THE DAY MAY ALSO ALLOW FOR LIGHT ACCUMULATIONS IN THE VALLEYS THERE...TOO. THE BULK OF THE PCPN MOVES OUT BY SUNDAY WITH JUST A SMALL CHANCE FOR A LEFT OVER SNOW SHOWER IN THE FAR EAST. OTHERWISE...THE NEXT CHANCE OF SNOW OR RAIN WILL NOT BE UNTIL MONDAY NIGHT AND CONTINUING INTO TUESDAY AS A SFC WAVE MOVES OUT OF THE PLAINS. THE CR GRID BLEND CAME IN DECENT ENOUGH...GIVEN THE PROMINENCE OF THE GFS. DID FINE TUNE THE POP GRIDS TO ENHANCE THEM IN THE HIGHER EASTERN TERRAIN AND DIMINISH THEM FURTHER WEST...AT LEAST THROUGH SATURDAY. ONLY MADE MINOR TERRAIN BASED ADJUSTMENTS TO TEMPERATURES THROUGH THE EXTENDED...MAINLY TO COOL THE RIDGES A BIT MORE DURING THE DAYS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1259 PM EST WED FEB 27 2013 MAINLY MVFR CONDITIONS WERE PRESENT AT TAF ISSUANCE...DUE TO CEILINGS. THERE WAS ALSO DRIZZLE IN MANY AREAS. LATE TODAY RAIN SHOULD DEVELOP OVER THE REGION FROM NW TO SE BETWEEN ABOUT 21Z AND 00Z. THE RAIN WILL MIX WITH SNOW FROM NW TO SE BETWEEN ABOUT 01Z AND 04Z...REDUCING VISIBILITY. VISIBILITY WILL VARY AS THE SNOW BEGINS... BUT ON AVERAGE SHOULD STILL BE MVFR. THE PRECIPITATION SHOULD THEN EASE SOMEWHAT AS IT CHANGES TO ALL SNOW FROM NW TO SE BETWEEN ABOUT 03Z AND 06Z. MAINLY LIGHT SNOW WILL THEN CONTINUE AT TIMES THROUGH THE REMAINDER OF THE PERIOD. CEILINGS ARE EXPECTED TO LOWER TO IFR FOR A PERIOD OF SEVERAL HOURS CENTERED AROUND DAWN...WITH MVFR CONDITIONS OTHERWISE EXPECTED OVERNIGHT AND ON THURSDAY. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...KAS LONG TERM...GREIF AVIATION...HAL
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
340 PM EST WED FEB 27 2013 .SYNOPSIS... AN UPPER LEVEL LOW WILL MOVE ACROSS THE AREA OVERNIGHT AND PUSH INTO THE NORTHEAST FOR THE END OF THE WEEK. AS THE LOW SHIFTS EAST OF THE REGION...COLDER AIR WILL FILTER INTO THE AREA TONIGHT AND ALLOW FOR A MIX OF RAIN AND SNOW SHOWERS TO CHANGE OVER TO MOSTLY SNOW SHOWERS INTO FRIDAY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A RATHER ELONGATED CLOSED UPPER LOW THAT STRETCHES ACROSS THE SOUTHERN GREAT LAKES AND OHIO VALLEY. AT THE SURFACE...A 999MB LOW IS CENTERED ACROSS SOUTHERN MICHIGAN WITH ANOTHER LOW DEVELOPING AS IT MOVES NORTHWARD ACROSS NEW JERSEY. THE LOW IN MICHIGAN IS DRIVING A SOUTHWESTERLY FLOW ACROSS THE AREA THIS TODAY. SOUNDINGS INDICATE A SFC-900MB MELTING LAYER STRONG ENOUGH TO ALLOW FOR PRECIP SOUTH AND WEST OF PITTSBURGH TO BE ALL RAIN. 1000-700MB 2840M THICKNESS LINE ALSO SEEMS TO COINCIDE FAIRLY WELL WITH RAIN/SNOW LINE NORTHEAST OF PITTSBURGH. THIS EVENING...THE BROAD UPPER LOW WILL SLOWLY MEANDER EASTWARD ACROSS THE OHIO VALLEY...WITH THE NEXT VORT LOBE SWINGING AROUND ITS BASE. WRF-ARW 1KM SIMULATED REFLECTIVITY DEPICTS MORE CONVECTIVE SHOWERS EARLY THIS EVENING...SO HAVE GONE WITH ISOLATED/SCATTERED INCREASING TO MORE NUMEROUS AS THE UPPER LOW APPROACHES FROM THE WEST. DESPITE COLDER AIR ADVECTING IN WITH THE COLD POOL ALOFT AND ASSOCIATED UPPER LOW...GFS/NAM SOUNDINGS CONTINUE TO INDICATE PRECIPITATION WILL FALL INITIALLY AS RAIN WITH A SUFFICIENT SFC-900MB MELTING LAYER REMAINING IN PLACE. THUS...FORECAST BEINGS WITH MOSTLY RAIN...EXCEPT FOR SOME RAIN-SNOW CLOSER TO 1000-700MB CRITICAL THICKNESS ACROSS THE NORTH AND WITH THE LACK OF A PRONOUNCED MELTING LAYER ACROSS THE RIDGES. OVERNIGHT...GFS/NAM AGREE THAT THE UPPER LOW WILL CROSS THE AREA AS IT SHIFTS FROM WESTERN OHIO INTO WESTERN NY. WEAK CAA AND COOLING SFC-900MB LAYER WILL ALLOW FOR ENTIRE COLUMN TO DROP BELOW FREEZING AND PRECIPITATION TO CHANGE OVER TO ALL SNOW SHOWERS TONIGHT. ACCUMULATIONS WILL BE AN INCH OR LESS FOR SOUTHWEST PA...EASTERN OHIO...AND NORTHERN WV WITH 1 TO 2 INCHES POSSIBLE TONIGHT ACROSS THE ALLEGHENY FRONT/LAUREL HIGHLANDS AND I-80 CORRIDOR. TEMPS TONIGHT ARE FAIRLY CLOSE TO A MAV/MET BLEND...WITH LOWS RANGING FROM THE MID 20S ACROSS THE EASTERN RIDGES TO THE LOWER 30S ELSEWHERE. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/... A MODEL CONSENSUS INDICATES THAT THE UPPER LOW WILL SLOWLY MEANDER EASTWARD INTO NEW ENGLAND THURSDAY AND FRIDAY...LEAVING THE UPPER OHIO VALLEY IN A MOIST...NORTHWESTERLY FLOW OFF OF THE GREAT LAKES. THE LOW-LEVEL FLOW WILL BE CLOSE TO ZONAL MUCH OF THE DAY THURSDAY AS A SERIES OF VORT LOBES ROTATES AROUND THE UPPER LOW AND INTO THE AREA. WITH SFC TEMPS WARMING TO THE MID TO UPPER 30S ACROSS THE LOWLANDS...ANTICIPATE LITTLE ACCUMULATION DURING DAYLIGHT HOURS ACROSS THE LOWLANDS. WITH SOME UPSLOPING AND TEMPS IN THE LOWER 30S...1 TO 2 INCHES WILL BE POSSIBLE ACROSS THE HIGHER ELEVATIONS. VORT ENERGY WILL SLIDE EAST OF THE UPPER OHIO VALLEY THURSDAY NIGHT INTO FRIDAY. DURING THIS TIME...THE LOW-LEVEL FLOW WILL VEER TO MORE NORTH-NORTHWESTERLY...ALLOWING FOR A MOISTURE FETCH OFF OF LAKE HURON WITH MOISTURE LACKING FROM A PARTIALLY FROZEN LAKE ERIE. ONE LIMITING FACTOR DESPITE THE NNWRLY FLOW WILL BE THAT THE AIR MASS WILL NOT BE QUITE COLD ENOUGH TO SUPPORT LAKE EFFECT. THUS...ANTICIPATE LITTLE MORE THAN SCATTERED SNOW SHOWERS THROUGH THIS PERIOD WITH AROUND AN INCH FOR THE LOWLANDS AND AN ADDITIONAL 1 TO 2 FOR THE RIDGES. TEMPS THROUGH THIS PERIOD WILL BE AROUND 5 DEGREES BELOW NORMAL WITH THE NORTHERLY COMPONENT CONTINUING TO PULL COOLER...CANADIAN AIR INTO THE AREA. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... ECMWF AND GFS INDICATE CONTD MAINTENANCE OF THE ERN NORTH AMERICAN TROF VIA SHRTWV ENERGY THRU THE LONG TERM PD. THE EXTENDED FORECAST THUS CONTINUES TO FEATURE SUB AVERAGE TEMPS AND NR CLIMO/CHC POPS UNTIL THE TROF AXIS SHIFT SUFFICIENTLY EWD...PROBABLY BY SATURDAY. SHRTWV RIDGE IN ADVN OF MIDWRN LOW IS CURRENTLY PROGGED TO SUPPRESS PRECIP PROBABILITIES...UNTIL THE LOW INITIATES PCPN LTR ON TUE. CONFIDENCE IN THAT PORTION OF THE FORECAST IS MINIMAL GIVEN PROJECTIONS OF A CUTOFF SYSTEM WITH QUESTIONS OF MAGNITUDE AND PLACEMENT OF THE LOW CENTERS. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... GENL MVFR WITH STRATOCU CIGS WITH REDEVELOPMENT OF RAIN AND SNOW SHOWERS CAN BE EXPECTED FOR THE TAF PD AS UPR LOW PRES DRIFTS ACRS THE REGION. .OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/... RESTRICTIONS ARE LIKLEY WITH CIGS AND -SHSN INTO THE WEEKEND. A RETURN TO WIDESPREAD VFR CONDITIONS MAY NOT OCCUR UNTIL SUNDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ SYNOPSIS...WOODRUM NEAR TERM...WOODRUM SHORT TERM...WOODRUM LONG TERM...15 AVIATION...15
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1259 PM EST WED FEB 27 2013 .SYNOPSIS... AN UPPER LEVEL LOW WILL MOVE ACROSS THE AREA TODAY AND PUSH INTO THE NORTHEAST FOR THE END OF THE WEEK. AS THE LOW SHIFTS EAST OF THE REGION...COLDER AIR WILL FILTER INTO THE AREA TONIGHT AND ALLOW FOR A MIX OF RAIN AND SNOW SHOWERS TODAY TO CHANGE OVER TO MOSTLY SNOW SHOWERS TONIGHT INTO FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AN EARLY AFTERNOON ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO BEGIN MIXING IN SNOW WITH RAIN SHOWERS 1-2 HOURS EARLIER ACROSS THE AREA THIS EVENING. THE REST OF THE PREVIOUS DISCUSSION REMAINS THE SAME. THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A RATHER ELONGATED CLOSED UPPER LOW THAT STRETCHES ACROSS THE SOUTHERN GREAT LAKES REGION. 500MB VORT ENERGY ALONG WITH 700MB OMEGA INDICATE THAT AN AREA OF LIFT SPAWNING MORE WIDESPREAD RAIN/SNOW THIS MORNING NORTHEAST OF PITTSBURGH HAS SHIFTED INTO NORTH-CENTRAL PA AND NEW YORK. NVA IN ITS WAKE IS ALLOWING FOR A BREAK IN PRECIPITATION ACROSS MOST OF THE AREA. AT THE SURFACE...A 999MB LOW IS CENTERED ACROSS SOUTHERN MICHIGAN WITH ANOTHER LOW DEVELOPING AS IT MOVES NORTHWARD ACROSS NEW JERSEY. THE LOW IN MICHIGAN IS DRIVING A SOUTHWESTERLY FLOW ACROSS THE AREA THIS TODAY. THE 12Z KPIT SOUNDING INDICATES A SFC-900MB MELTING LAYER STRONG ENOUGH TO ALLOW FOR MOSTLY PRECIP SOUTH AND WEST OF PITTSBURGH TO BE ALL RAIN. 1000-700MB 2840M THICKNESS LINE ALSO SEEMS TO COINCIDE FAIRLY WELL WITH RAIN/SNOW LINE NORTHEAST OF PITTSBURGH. THIS AFTERNOON...THE BROAD UPPER LOW WILL SLOWLY MEANDER EASTWARD ACROSS THE OHIO VALLEY...WITH THE NEXT VORT LOBE SWINGING AROUND ITS BASE THIS EVENING. WRF-ARW 1KM SIMULATED REFLECTIVITY DEPICTS MORE CONVECTIVE SHOWERS THIS AFTERNOON AND EARLY EVENING...SO HAVE GONE WITH ISOLATED/SCATTERED INCREASING TO MORE NUMEROUS AS THE UPPER LOW APPROACHES FROM THE WEST. 850MB TEMPS WILL COOL FROM -1 TO -2C TO -3 TO -4C BY THIS EVENING. DESPITE COLDER AIR ADVECTING IN WITH THE COLD POOL ALOFT AND ASSOCIATED UPPER LOW...GFS/NAM SOUNDINGS CONTINUE TO INDICATE PRECIPITATION WILL FALL AS MOSTLY RAIN TODAY WITH A SUFFICIENT SFC-900MB MELTING LAYER REMAINING IN PLACE. THUS...HAVE GONE WITH MOSTLY RAIN IN THE FORECAST TODAY...EXCEPT FOR SOME RAIN-SNOW CLOSER TO 1000-700MB CRITICAL THICKNESS ACROSS THE NORTH AND WITH THE LACK OF A PRONOUNCED MELTING LAYER ACROSS THE RIDGES. SOUTHWESTERLY FLOW WILL ALLOW TEMPS TO WARM A FEW DEGREES THIS AFTERNOON...WITH HIGHS CLOSE TO LAMP GUIDANCE...RANGING FROM THE MID 30S ACROSS THE EASTERN RIDGES TO THE MID 40S SOUTH AND WEST OF PITTSBURGH. TONIGHT...GFS/NAM AGREE THAT THE UPPER LOW WILL CROSS THE AREA AS IT SHIFTS FROM WESTERN OHIO INTO WESTERN NY. WEAK CAA AND COOLING SFC-900MB LAYER WILL ALLOW FOR ENTIRE COLUMN TO DROP BELOW FREEZING AND PRECIPITATION TO CHANGE OVER TO ALL SNOW SHOWERS TONIGHT. ACCUMULATIONS WILL BE AN INCH OR LESS FOR SOUTHWEST PA...EASTERN OHIO...AND NORTHERN WV WITH 1 TO 2 INCHES POSSIBLE TONIGHT ACROSS THE ALLEGHENY FRONT/LAUREL HIGHLANDS AND I-80 CORRIDOR. TEMPS TONIGHT ARE FAIRLY CLOSE TO A MAV/MET BLEND...WITH LOWS RANGING FROM THE MID 20S ACROSS THE EASTERN RIDGES TO THE LOWER 30S ELSEWHERE. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... MATURE/STACKED AND COLD LOW PRES WILL WOBBLE ACROSS THE REGION THROUGH THURSDAY...AND DIG OFF THE COAST BY FRIDAY ACCORDING TO THE LATEST MODEL SOLNS. SCT TO NMRS SHSN WL THUS CONT TO PLAGUE THE REGION FOR THE SHORT TERM PD...WITH UPSLOPE COMPONENT OF WIND ENHANCING SN POTENTIAL IN THE RIDGES. OVERALL ACCUMULATION POTENTIAL WL BE RETARDED OVR AREAS WHERE DAYTIME TEMPS RISE ABOVE FREEZING...SO HEADLINE POTENTIAL IS LIMITED. THE EXCEPTION MAY BE FOR THE RIDGES WHERE PROLONGED SHSN MAY REQUIRE A COUPLE-DAY ADVISORY. FOR NOW...WL MENTION IN THE HAZARDOUS WEATHER OUTLOOK AND TASK FUTURE SHIFTS TO MONITOR. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ECMWF AND GFS INDICATE CONTD MAINTENANCE OF THE ERN NORTH AMERICAN TROF VIA SHRTWV ENERGY THRU THE LONG TERM PD. THE EXTENDED FORECAST THUS CONTINUES TO FEATURE SUB AVERAGE TEMPS AND NR CLIMO/CHC POPS UNTIL THE TROF AXIS SHIFT SUFFICIENTLY EWD...PROBABLY BY SUNDAY. SHRTWV RIDGE IN ADVN OF MIDWRN LOW IS CURRENTLY PROGGED TO SUPPRESS PRECIP PROBABILITIES...UNTIL THE LOW INITIATES PCPN LTR ON TUE. CONFIDENCE IN THAT PORTION OF THE FORECAST IS MINIMAL GIVEN PROJECTIONS OF A CUTOFF SYSTEM WITH QUESTIONS OF MAGNITUDE AND PLACEMENT OF THE LOW CENTERS. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... GENL MVFR WITH STRATOCU CIGS WITH REDEVELOPMENT OF RAIN AND SNOW SHOWERS CAN BE EXPECTED FOR THE TAF PD AS UPR LOW PRES DRIFTS ACRS THE REGION. .OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/... RESTRICTIONS ARE LIKLEY WITH CIGS AND -SHSN INTO THE WEEKEND. A RETURN TO WIDESPREAD VFR CONDITIONS MAY NOT OCCUR UNTIL LATE SUNDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ SYNOPSIS...WOODRUM NEAR TERM...WOODRUM AVIATION...15
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1114 AM EST WED FEB 27 2013 .SYNOPSIS... AN UPPER LEVEL LOW WILL MOVE ACROSS THE AREA TODAY AND PUSH INTO THE NORTHEAST FOR THE END OF THE WEEK. AS THE LOW SHIFTS EAST OF THE AREA...COLDER AIR WILL FILTER INTO THE AREA TONIGHT AND ALLOW FOR A MIX OF RAIN AND SNOW SHOWERS TODAY TO CHANGE OVER TO MOSTLY SNOW SHOWERS TONIGHT INTO FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AN ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO ACCOUNT FOR THE LATEST TRENDS IN TEMP AND RADAR AS A MIX OF RAIN SNOW DIMINISHES NORTHEAST OF PITTSBURGH. THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A RATHER ELONGATED CLOSED UPPER LOW THAT STRETCHES ACROSS THE SOUTHERN GREAT LAKES REGION. 500MB VORT ENERGY ALONG WITH 700MB OMEGA INDICATE THAT AN AREA OF LIFT SPAWNING MORE WIDESPREAD RAIN/SNOW THIS MORNING NORTHEAST OF PITTSBURGH IS SHIFTING INTO NORTH-CENTRAL PA AND NEW YORK. NVA IN ITS WAKE IS ALLOWING FOR A BREAK IN PRECIPITATION MOVING FROM EASTERN OHIO INTO WESTERN PA. AT THE SURFACE...A 999MB LOW IS CENTERED ACROSS SOUTHERN MICHIGAN WITH ANOTHER LOW DEVELOPING AS IT MOVES NORTHWARD ACROSS NEW JERSEY. THE LOW IN MICHIGAN IS DRIVING A SOUTHWESTERLY FLOW ACROSS THE AREA THIS TODAY. THE 12Z KPIT SOUNDING INDICATES A SFC-900MB MELTING LAYER STRONG ENOUGH TO ALLOW FOR MOSTLY PRECIP SOUTH AND WEST OF PITTSBURGH TO BE ALL RAIN. 1000-700MB 2840M THICKNESS LINE ALSO SEEMS TO COINCIDE FAIRLY WELL WITH RAIN CHANGING TO SNOW NORTHEAST OF PITTSBURGH. TODAY...THE BROAD UPPER LOW WILL SLOWLY MEANDER EASTWARD ACROSS THE OHIO VALLEY...WITH THE NEXT VORT LOBE SWINGING AROUND ITS BASE THIS EVENING. WRF-ARW 1KM SIMULATED REFLECTIVITY DEPICTS MORE CONVECTIVE SHOWERS THIS AFTERNOON AND EARLY EVENING...SO HAVE GONE WITH ISOLATED/SCATTERED INCREASING TO MORE NUMEROUS AS THE UPPER LOW APPROACHES FROM THE WEST. 850MB TEMPS WILL COOL FROM -1 TO -2C TO -3 TO -4C BY THIS EVENING. DESPITE COLDER AIR ADVECTING IN WITH THE COLD POOL ALOFT AND ASSOCIATED UPPER LOW...GFS/NAM SOUNDINGS CONTINUE TO INDICATE PRECIPITATION WILL FALL AS MOSTLY RAIN TODAY WITH A SUFFICIENT SFC-900MB MELTING LAYER REMAINING IN PLACE. THUS...HAVE GONE WITH MOSTLY RAIN IN THE FORECAST TODAY...EXCEPT FOR SOME RAIN-SNOW CLOSER TO 1000-700MB CRITICAL THICKNESS ACROSS THE NORTH AND WITH THE LACK OF A PRONOUNCED MELTING LAYER ACROSS THE RIDGES. SOUTHWESTERLY FLOW WILL ALLOW TEMPS TO WARM A FEW DEGREES THIS AFTERNOON...WITH HIGHS CLOSE TO LAMP GUIDANCE...RANGING FROM THE MID 30S ACROSS THE EASTERN RIDGES TO THE MID 40S SOUTH AND WEST OF PITTSBURGH. TONIGHT... GFS/NAM AGREE THAT THE UPPER LOW WILL CROSS THE AREA AS IT SHIFTS FROM WESTERN OHIO INTO WESTERN NY. WEAK CAA AND COOLING SFC-900MB LAYER WILL ALLOW FOR ENTIRE COLUMN TO DROP BELOW FREEZING AND PRECIPITATION TO CHANGE OVER TO ALL SNOW SHOWERS TONIGHT. ACCUMULATIONS WILL BE AN INCH OR LESS FOR SOUTHWEST PA...EASTERN OHIO...AND NORTHERN WV WITH 1 TO 2 INCHES POSSIBLE TONIGHT ACROSS THE ALLEGHENY FRONT/LAUREL HIGHLANDS AND I-80 CORRIDOR. TEMPS TONIGHT ARE FAIRLY CLOSE TO A MAV/MET BLEND...WITH LOWS RANGING FROM THE MID 20S ACROSS THE EASTERN RIDGES TO THE LOWER 30S ELSEWHERE. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... MATURE/STACKED AND COLD LOW PRES WILL WOBBLE ACROSS THE REGION THROUGH THURSDAY...AND DIG OFF THE COAST BY FRIDAY ACCORDING TO THE LATEST MODEL SOLNS. SCT TO NMRS SHSN WL THUS CONT TO PLAGUE THE REGION FOR THE SHORT TERM PD...WITH UPSLOPE COMPONENT OF WIND ENHANCING SN POTENTIAL IN THE RIDGES. OVERALL ACCUMULATION POTENTIAL WL BE RETARDED OVR AREAS WHERE DAYTIME TEMPS RISE ABOVE FREEZING...SO HEADLINE POTENTIAL IS LIMITED. THE EXCEPTION MAY BE FOR THE RIDGES WHERE PROLONGED SHSN MAY REQUIRE A COUPLE-DAY ADVISORY. FOR NOW...WL MENTION IN THE HAZARDOUS WEATHER OUTLOOK AND TASK FUTURE SHIFTS TO MONITOR. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ECMWF AND GFS CONT TO INDICATE DEVELOPMENT OF AN ERN NORTH AMERICAN TROF FOR THE LONG TERM PD. THE EXTENDED FORECAST THUS CONTINUES TO FEATURE SUB AVERAGE TEMPS AND NR CLIMO. CHC POPS DEPENDENT ON SPPRTG SHRTWV ENERGY FOR THE INTIAL PDS. SHRTWV RIDGE IN ADVN OF MIDWRN LOW SHOULD REDUCE THOSE POPS BY MONDAY...BUT THAT REPRIEVE LOOKS TO BE BRIEF AS PCPN FM THAT SYSTEM IS CURRENTLY TIMED FOR A TUE INITIATION OVR THE UPR OH VALLEY. && .AVIATION /16Z WEDNESDAY THROUGH SUNDAY/... GENL MVFR WITH STRATOCU CIGS AND PERIODIC RAIN AND SNOW SHOWERS CAN BE EXPECTED FOR THE TAF PD AS UPR LOW PRES DRIFTS ACRS THE REGION. .OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/... RESTRICTIONS ARE POSSIBLE IN RAIN OR SNOW SHOWERS THROUGH FRIDAY. BEST CHANCE FOR A RETURN TO WIDESPREAD VFR CONDITIONS MAY NOT ARRIVE UNTIL LATE SAT/SUN. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ SYNOPSIS...WOODRUM NEAR TERM...WOODRUM AVIATION...15
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
429 PM EST WED FEB 27 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 426 PM EST WED FEB 27 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A BROAD MID LEVEL LOW CIRCULATION OVER THE GREAT LAKES/OHIO VALLEY. AT THE SFC...A WEAKENING LOW PRES CENTER WAS LOCATED NEAR FLINT. SYSTEM ENDED UP SLIGHTLY FARTHER N THAN EXPECTED YESTERDAY...AND THUS THE ASSOCIATED WEAKENING SNOW SHIELD WAS ABLE TO SPREAD FARTHER N AND W INTO UPPER MI TODAY...AIDED BY A SHORTWAVE THAT PIVOTED AROUND THE LARGE MID LEVEL LOW CIRCULATION. THE NW EDGE OF THE -SN HAS SPREAD TO ABOUT A BIG BAY/CHAMPION/CRYSTAL FALLS LINE. SNOW ACCUMULATIONS HAVE GENERALLY BEEN 1 INCH OR LESS THOUGH SOME 2-3 INCH AMOUNTS WERE OBSERVED ACROSS MENOMINEE/DELTA/SRN SCHOOLCRAFT COUNTIES. SINCE THE WEAKENING SHORTWAVE AND ASSOCIATED DEEP LAYER FORCING ASSOCIATED WITH THE HEAVIER SNOW HAS ROTATED TO THE SW...-SN HAS BEEN DIMINISHING IN AREAL COVERAGE FROM LATE MORNING THRU THE AFTN. AS EXPECTED...THERE HAS NOT BEEN ANY EVIDENCE OF LES TODAY DESPITE CYCLONIC NE FLOW AS AIR MASS HAS BEEN TOO WARM. IN FACT...ON VIS SATELLITE IMAGERY...HIGH CLOUDS ARE AT TIMES THIN ENOUGH TO REVEAL LITTLE IF ANY LAKE EFFECT CLOUDS OVER LAKE SUPERIOR. THE SNOW THAT HAS RECENTLY INCREASED INTO NCNTRL UPPER MI APPEARS MOSTLY RELATED TO A LONG ARC OF ISENTROPIC ASCENT EXTENDING W FROM NEW ENGLAND... BUT IT CERTAINLY LOOKS LIKE THERE MAY NOW BE A LAKE COMPONENT TO THIS HEAVIER SNOW THAT HAS DEVELOPED. IN THE SHORT TERM...FOCUS SHIFTS FROM REMNANT -SN ASSOCIATED WITH SLOWLY DEPARTING GREAT LAKES/OHIO VALLEY MID LEVEL LOW TO POTENTIAL OF LES OFF LAKE SUPERIOR. WITH NO ADDITIONAL SHORTWAVES EVIDENT PIVOTING TOWARD UPPER MI AND WITH MODELS INDICATING INCREASING DEEP LAYER QVECTOR CONVERGENCE WITH TIME...EXPECT LINGERING AREAS OF -SN OVER ROUGHLY THE E HALF OF UPPER MI TO CONTINUE TO DIMINISH TONIGHT. ANY ADDITIONAL SNOW ACCUMULATION WILL BE LESS THAN 1 INCH. ATTENTION THEN TURNS TO POTENTIAL LES OFF LAKE SUPERIOR. HIGHER RES MODEL GUIDANCE CONTINUES TO POINT TOWARD LES/UPSLOPE ENHANCED SNOW TONIGHT. ALTHOUGH DEEPER MOISTURE/SATURATION AND SYNOPTIC -SN IS SPREADING OUT OVER ERN LAKE SUPERIOR...HAVE DOUBTS ON THE INSISTENCE OF HIGH RES GUIDANCE TO OUTPUT IN WHAT SOME CASES ARE SIGNIFICANT PCPN TOTALS TONIGHT (REGIONAL GEM SHOWS AROUND 0.5 INCHES OF PCPN TONIGHT OVER THE HIGHER TERRAIN OF MARQUETTE COUNTY...LOCAL HIGH RESWRF 0.3-0.4...06Z NAM SHOWED UPWARDS OF 1 INCH BUT 12Z NAM AT LEAST TRENDED DOWN TO WHAT SHOULD BE A MORE REASONABLE 0.2-0.3). 850MB TEMPS OF ONLY -6 TO -9C ACROSS LAKE SUPERIOR WILL NOT BE SUFFICIENT FOR LES. SO...ONCE THE ISENTROPIC ASCENT CURRENTLY AIDING THE SNOW INTO NCNTRL UPPER MI FALLS APART TONIGHT...EXPECT THE SNOW TO DIMINISH SIGNIFICANTLY. WILL THUS CARRY HIGH POPS INTO NCNTRL UPPER MI THIS EVENING...THEN DIMINISH PCPN TO JUST SCT -SHSN OVERNIGHT. EXPECT A FEW INCHES OF SNOW ACCUMULATION THRU THE EVENING ACROSS THE HIGHER TERRAIN OF THE NCNTRL (MARQUETTE COUNTY IN PARTICULAR). IF THE ONGOING SNOW SHOWS SIGNS OF PERSISTENCE AND LITTLE MOVEMENT (HEAVIEST SNOW IS CURRENTLY OCCURRING FROM MARQUETTE/HARVEY WSW TO ISHPEMING/GWINN) WILL LIKELY NEED TO HOIST AN ADVY. FARTHER W...LACKING SYNOPTIC FORCING...NOTHING MORE THAN DEVELOPING CHC POPS/SCT -SHSN APPEAR REASONABLE. 850MB TEMPS FALL ANOTHER DEGREE OR TWO THU...BUT EVEN THAT WILL STILL NOT BE QUITE COLD ENOUGH FOR LES. WITH ANY DEEPER MOISTURE EXITING AND SINCE THERE WILL PROBABLY BE SOME NEGATIVE IMPACT DUE TO DAYTIME HEATING WITH HIGHER SUN ANGLE AT THIS TIME OF YEAR...SCT -SHSN OFF THE LAKE SHOULD WIND DOWN DURING THE DAY. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 426 PM EST WED FEB 27 2013 PREFERRED THE 00Z/27 ECMWF AND GLOBAL GEM OVER THE 12Z/27 GFS FOR THE ENTIRE LONG TERM SINCE THE GFS HAS DISPLAYED POOR RUN TO RUN CONTINUITY AND LACKS AGREEMENT WITH OTHER MODELS. KEPT DIMINISHING CHANCES OF LAKE EFFECT SNOW THU NIGHT INTO EARLY FRI IN AREAS FAVORED BY NE LOW LEVEL WINDS...BUT PUSHED BACK WHEN POPS GO AWAY ENTIRELY BY AROUND 3 HOURS TO 18Z FRI. AFTER THAT...VERY DRY LOW LEVELS ASSOCIATED WITH A SFC AND 500MB RIDGE PUSHING INTO THE CWA. LOW LEVEL FLOW WILL CONTINUE TO BE OUT OF THE N/NE UNTIL THE SFC RIDGE AXIS COMPLETELY PASSES SUN NIGHT WITH SLIGHTLY COLDER 850MB TEMPS...SO WILL KEEP INCREASED CLOUD COVER NEAR LAKE SUPERIOR. MAY SEE A BRIEF RETURN OF NE FLOW LES LATE FRI NIGHT WITH THE PASSAGE OF A 500MB TROUGH...BUT ANY ACCUMULATIONS WILL BE MINOR. THE STORY FOR SUN THROUGH NEXT WED IS THAT A 500MB LOW WILL MOVE OVER THE CWA THROUGH TUE BEFORE MOVE S ON WED. AT THE SAME TIME...INCREASINGLY STRONG SFC RIDGING WILL MOVE INTO THE CWA...SO PRECIP WILL BE AT A MINIMUM. PRECIP...IF ANY...WILL BE MINOR SO SLIGHT CHANCE POPS AT BEST SEEM APPROPRIATE. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1238 PM EST WED FEB 27 2013 GUSTY N/NE WINDS WILL BE THE RULE AT KIWD/KCMX/KSAW THRU THIS FCST PERIOD AS TIGHT PRES GRADIENT REMAINS IN PLACE ACROSS THE UPPER GREAT LAKES. WIND DIRECTION IS MOST FAVORABLE FOR ENHANCED WINDS AT KSAW...AND GUSTS THERE SHOULD BE IN THE 20-30KT RANGE THROUGHOUT THE FCST PERIOD. AT KIWD...UPSLOPE N/NNE WINDS WILL LIKELY KEEP LOW MVFR CIGS IN PLACE THRU THE FCST PERIOD. AS AIR MASS COOLS SLIGHTLY... LAKE EFFECT -SHSN MAY GET UNDERWAY TONIGHT...BUT EXPECTATION IS FOR ANY SHSN TO BE LIGHT AND NOT SIGNIFICANTLY REDUCE VIS. AT KCMX...LOW CLOUDS HAVE SCATTERED OUT...BUT LOWER CLOUDS TO THE NE OF LAKE SUPERIOR SHOULD ADVECT SW AND BRING A RETURN TO MVFR CIGS AT KCMX LATE IN THE AFTN. MAY SEE A FEW FLURRIES LATER TONIGHT AT KCMX. AT KSAW...IDEAL USPLOPE FLOW AND PERIODS OF -SN SHOULD RESULT IN IFR CONDITIONS PREVAILING FOR THE NEXT SEVERAL HRS. SOME IMPROVEMENT TO LOW MVFR SHOULD OCCUR LATE AFTN WITH LOW MVFR CONDITIONS CONTINUING THRU THU MORNING UNDER UPSLOPE NORTHERLY FLOW. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 426 PM EST WED FEB 27 2013 TIGHT PRES GRADIENT BTWN HIGH PRES TO THE N AND NW AND LOW PRES TRACKING THRU THE LWR LAKES WILL RESULT IN NORTHEASTERLY WINDS OF 20-30KT ACROSS LAKE SUPERIOR THRU THU. GALE FORCE GUSTS SHOULD BE FREQUENT ENOUGH TO MAINTAIN GALE WARNING FOR THE E HALF OF LAKE SUPERIOR. IN ADVANCE OF HIGH PRES RIDGE BUILDING TOWARD THE AREA FRI...TIGHT PRES GRADIENT WILL REMAIN...RESULTING IN CONTINUED 20-30KT NE WINDS. THE STRONG WINDS/HIGH WAVES AND INFLUX OF COLDER AIR WILL RESULT IN FREEZING SPRAY DEVELOPING TONIGHT AND CONTINUING THRU FRI NIGHT. HVY FREEZING SPRAY MAY OCCUR FOR A TIME THU NIGHT/FRI MORNING. WINDS WILL THEN DIMINISH FROM W TO E FRI NIGHT AS HIGH PRES RIDGE MOVES CLOSER. ON SAT...WINDS SHOULD BE BLO 20KT ACROSS THE ENTIRE LAKE. LIGHT WINDS...MOSTLY 10KT OR LESS...ARE EXPECTED SUN/MON AS SFC HIGH PRES RIDGE WILL EXTEND FROM HUDSON BAY S ACROSS THE UPPER LAKES. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... GALE WARNING UNTIL 10 AM EST THURSDAY FOR LSZ244-245-248>250- 264>267. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...TITUS AVIATION...ROLFSON MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
249 PM CST WED FEB 27 2013 .DISCUSSION... STACKED LOW PRESSURE SYSTEM OVER THE EASTERN GREAT LAKES WILL CONTINUE TO SPONSOR CLOUDS OVER THE LOCAL FORECAST AREA ON ITS WESTERN PERIPHERY...ALONG WITH WEAK LIFT OVER WEST CENTRAL WI. HAVE INCLUDED HIGH POPS OVER WEST CENTRAL WI THIS EVENING. HAVE ALSO INCLUDED A MENTION OF SCATTERED FLURRIES FROM WEST INTO SOUTH CENTRAL MN WHERE WEAK FRONTOGENESIS IS PROGGED FROM 700-600MB TONIGHT INTO THURSDAY MORNING. DESPITE THE EXTENSIVE CLOUD COVER...TEMPS HAVE WARMED INTO THE UPPER 20S TO UPPER 30S NEARLY CWA-WIDE TODAY. CLOUDS AND WINDS HOLD TIGHT TONIGHT...SO THINK MOS NUMBERS APPEAR TOO COLD. HAVE LEANED TOWARD THE BIAS CORRECTED MOS...WHICH YIELDS UPPER TEENS TO UPPER 20S FOR LOWS TONIGHT. THURSDAY THROUGH SUNDAY WILL BE RATHER BENIGN LOCALLY...AS THE AREA REMAINS WEDGED BETWEEN A NORTHEASTERN CONUS TROUGH AND A BROAD WESTERN RIDGE. NORTHERLY FLOW WILL KEEP TEMPERATURES ON THE COOL SIDE OF NORMAL THROUGH THE WEEKEND HOWEVER...WITH HIGHS GENERALLY RUNNING 5 TO 10 DEGREES BELOW CLIMATOLOGY FOR EARLY MARCH. SINGLE DIGIT LOWS APPEAR LIKELY FOR THE MAJORITY OF THE FORECAST AREA ON BOTH WEEKEND MORNINGS AS WELL. THE 12Z SUITE OF MODELS TRENDED TO A SCENARIO MORE FAVORABLE FOR SNOWFALL IN CENTRAL/SOUTHERN MN...NAMELY THE ECMWF WHICH HAD BEEN THE MOST OPPOSED PRIOR TO TODAY. IT NOW TRACKS A SURFACE LOW ACROSS SOUTH DAKOTA AND IOWA...WITH A PROLONGED PERIOD OF MEASURABLE SNOWFALL FROM WEST INTO SOUTH CENTRAL MN. WHILE MODELS ARE STILL NOTABLY VARIABLE REGARDING THE TRACK/AMPLITUDE OF THIS TROUGH...THE RECENT CHANGE OF THE ECMWF HAS INCREASED CONFIDENCE FOR AT LEAST MEASURABLE SNOW LOCALLY. HAVE THEREFORE INCREASED POPS TO 50-60 PERCENT FOR WEST/SOUTH CENTRAL MN ON MONDAY AND MONDAY NIGHT...WITH 20-40S FROM CENTRAL MN INTO WEST CENTRAL WI. REGARDING TEMPERATURES IN THE EXTENDED...HIGHS SHOULD GENERALLY RANGE AROUND 5 DEGREES BELOW NORMAL FROM MONDAY THROUGH THE MIDDLE OF NEXT WEEK...WITH LOWS A FEW DEGREES ON EITHER SIDE OF NORMAL. && .AVIATION.../18Z TAF ISSUANCE/ TERMINALS WILL BE UNDER THE INFLUENCE OF EXPANSIVE VERTICALLY STACKED AND OCCLUDED LOW NOW NEAR DETROIT THIS ENTIRE TAF PERIOD. FOR THESE TAFS...FAVORED THE RAP HEAVILY...BLENDED A BIT WITH LAMP GUIDANCE. THE 925 MB RAP RH HAS BEEN PERFORMING WELL WITH ERODING OUT WEST END OF MVFR CIGS ACROSS ERN MN. THE RAP HAS BEEN CONSISTENT WITH PUSHING THESE CIGS EAST THROUGH THE MORNING...BEFORE QUICKLY BRINGING THIS MOISTURE SOUTHWEST ACROSS THE REST OF THE MPX CWA THIS AFTERNOON. FOR BRINGING CIGS BACK IN TO RWF/AXN/STC...BLENDED RAP TIMING IN WITH THE SLOWER LAMP GUIDANCE...THOUGH DID FAVOR THE RAP. ONCE THESE CLOUDS MOVE IN...HEIGHTS SHOULD BE FAIRLY CONSISTENT THE REST OF THE TAF PERIOD...WITH NO SIGNS OF SIGNIFICANT CLEARING WORKING INTO THE MPX AREA UNTIL CLOSER TO 00Z...OR LATE THU AFTERNOON. BESIDE CLOUDS...ALSO SEEING A BAND OF MAINLY MVFR SNOW ACROSS CENTRAL WI SLOWLY WORKING WEST. HRRR REFLECTIVITY FORECAST HAS HAD A GOOD HANDLE ON THIS SNOW THIS MORNING...SO FOLLOWED IT FOR TIMING SNOW ACROSS WRN WI. WILL START OFF EAU WITH -SN...WITH THE EXPECTATION THAT SNOW SHOULD BREAK OUT THERE BY 1830Z. MAINLY MVFR VIS RESTRICTIONS ARE EXPECTED...THOUGH WITH THE OCCASIONAL IFR VIS EAST OF EAU...DID KEEP A TEMPO IFR GROUP FOR A BIT THIS AFTERNOON. THIS SNOW WILL LIKELY GRAZE RNH AND STAY SE OF MSP...THOUGH MAY IMPACT FIELD SUCH AS K21D AND KSGS. FOR WINDS...NOT EXPECTING MUCH VARIATION IN DIRECTION THIS PERIOD...WITH JUST AN EVERY SO GRADUAL BACKING TOWARD THE NNW EXPECTED. WILL CONTINUE WITH GUSTS INTO THIS EVENING...BUT THINGS LOOKS TO SETTLE DOWN TONIGHT...WITH NO GUSTS EXPECTED TOMORROW WITH TYPICAL DIURNAL STRENGTHENING. KMSP...RAP HAS BEEN PRETTY CONSISTENT WITH RETURN TO VFR CIGS CURRENTLY OBSERVED. CONFIDENCE IS HIGH WE WILL RETURN TO AROUND 2K FT CIGS..BUT THERE IS LESS CONFIDENCE ON WHEN THEY RETURN...WITH IT POSSIBLY BEING CLOSER TO 00Z BEFORE GOING BACK TO MVFR. IN ADDITION...BAND OF SNOW OUT BY EAU WILL MAKE A RUN FOR MSP...AND BASED ON THE RAP/HRRR...MAY SEE A BRIEF SNOW SHOWER BETWEEN 00Z AND 03Z...THOUGH CONFIDENCE IN THIS HAPPENING NOT HIGH ENOUGH TO INCLUDE IN THE TAF ATTM. OTHER CONCERN THIS TAF PERIOD WILL BE WITH CIG HEIGHTS. KEPT THEM ABOVE 017 FOR NOW...BUT CERTAINLY IS POSSIBLE THAT CIGS COULD DROP TO AROUND 015 LATE TONIGHT INTO THU MORNING. ANY IMPROVEMENTS BACK TO VFR NOT EXPECTED UNTIL NEAR THE END OF OR SHORTLY AFTER THIS TAF PERIOD. /OUTLOOK FOR KMSP/ FRI...VFR WITH MVFR CIGS POSSIBLE. N WIND 5-10 KTS. SAT...VFR. N WIND 5 KTS. SUN...VFR. SE WIND 5 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ LS/MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1150 AM CST WED FEB 27 2013 .UPDATE... 18Z AVIATION DISCUSSION ADDED BELOW. && .PREV DISCUSSION.../ISSUED AT 356 AM CST WED FEB 27 2013/ OVERVIEW...ONLY MINOR ADJUSTMENTS TO POPS/WX/TEMPS WITH THE MORNING FORECAST PACKAGE. LIGHT SNOW POSSIBLE IN WEST CENTRAL WI THIS AFTERNOON AND EVENING. VERY LIGHT SNOW OR FLURRIES COULD MAKE IT INTO FAR EASTERN MN...BUT KEPT THE TWIN CITIES METRO SNOW FREE AT THIS POINT. WE REMAIN ON THE EASTERN FRINGE OF A CLIPPER SYSTEM ON MONDAY. PLENTY OF CLOUD COVER AT MULTIPLE LEVELS ACROSS MN/WI IN RESPONSE TO LARGE TROUGH STRETCHING FROM THE ROCKIES TO THE EAST COAST. THE CENTER OF THE LONG SINCE OCCLUDED CYCLONE IS LOCATED ALONG THE MI/OH BORDER EARLY THIS MORNING...BUT THE WESTWARD EXTENSION OF THE TROUGH IS STILL SPREADING MODERATE SNOW ACROSS WI AND IA. OUR WESTERN CWA COULD EVEN GET IN ON SOME LIGHT SNOW LATE THIS MORNING AND AFTERNOON. 27.00Z NAM IS PROBABLY THE MOST AGGRESSIVE WITH THE WESTWARD PROPAGATION OF A 700-600 MB FGEN BAND AND OMEGA INTO WEST CENTRAL WI. ASSORTED SHORT-RANGE MODEL GUIDANCE...SUCH AS THE HRRR/RAP/HOP-WRF SHOW A BAND OF SYNTHETIC REFLECTIVITY MOVING INTO WESTERN WI TODAY. AS A RESULT...INCREASED POPS IN A FEW OF OUR WI COUNTIES...INCLUDING EAU CLAIRE. NOT SUPREMELY CONFIDENT IN MEASURABLE SNOW...BUT A DUSTING IS PLAUSIBLE AND AS MUCH AS 1/2" TO 3/4" IS CERTAINLY POSSIBLE. EVEN THE TWIN CITIES METRO COULD SEE A FEW FLURRIES...ALTHOUGH LEFT THE FORECAST FOR MN MAINLY WEATHER FREE TODAY AND TONIGHT. THE SOUTHWARD EXTENT OF THE 0 C 850 MB ISOTHERM IS IMPRESSIVE OVER THE NEXT SEVERAL DAYS. CURRENTLY...IT STRETCHES FROM ROUGHLY NORTHERN CALIFORNIA...TO TEXAS...TO NORTHERN SOUTH CAROLINA. BY THE WEEKEND THE COLD AIR COULD BE AS FAR SOUTH AS SOUTHERN FLORIDA. WHILE THIS MEANS WELL-BELOW NORMAL TEMPERATURES FOR PARTS OF THE COUNTRY...IT ACTUALLY REMAINS NEAR NORMAL FOR MN/WI. THERE WILL HOWEVER BE A SLIGHTLY COOLING TREND LATE THIS WEEK AS NORTHERLY FLOW KEEPS WEAK COLD AIR ADVECTION GOING FOR THE NEXT FEW DAYS. THE COLDEST MORNING APPEARS TO BE SATURDAY MORNING WHERE WE COULD SEE WIDESPREAD SINGLE DIGITS AND LOWER TEENS. IF WE COULD GUARANTEE NO CLOUD COVER...THEN SOME SITES WOULD CERTAINLY BE BELOW ZERO GIVEN THE SNOW COVER AND POSITION OF THE SURFACE PRESSURE RIDGE. BESIDES THE LIGHT SNOW IN WI TODAY...THE ONLY SIGNIFICANT CHANCE FOR PRECIP IS WITH A SYSTEM DROPPING SOUTH OUT OF ALBERTA IN THE MONDAY/TUESDAY TIME FRAME. THE LAST 4-5 RUNS OF THE GFS/ECMWF HAVE GENERALLY TRENDED WEST WITH THE LOW TRACK...WITH A SLIGHT WOBBLE HERE AND THERE. WOULD HAVE TO SAY THAT THERE IS DECENT AGREEMENT BETWEEN THE GEM/GFS/ECMWF/FIM WITH THE SYSTEM EARLY NEXT WEEK. ALL SOLUTIONS WOULD EITHER FAVOR A MUCH BETTER CHANCE FOR LIGHT SNOW IN WESTERN MN...OR BEND MOST OF THE PRECIP AROUND THE FORECAST AREA ALL TOGETHER. VIEWING ALL THE GEFS MEMBERS INDIVIDUALLY... THERE SEEMS TO ONE TIGHTER CLUSTERING OF LOW TRACKS THAT ARE SIMILAR TO THE OPERATIONAL 27.00Z GFS. ALTHOUGH...THERE ARE STILL SEVERAL MEMBERS WITH A MORE EASTERLY SOLUTION...SO THE ENSEMBLE MEAN IS THEREFORE A BIT FARTHER EAST THAN THE 00Z GFS. RIGHT NOW THE AXIS OF HEAVIEST QPF FALLS IN THE DAKOTAS AND/OR NORTHERN NE...WITH 0.30-0.40"...WHICH WOULD BE GOOD ENOUGH FOR A HIGH END ADVISORY OR A LOW END WARNING. WE`LL HAVE TO WATCH TO SEE IF THERE IS AN EASTWARD TREND WITH TIME. AT THIS POINT...THERE IS ONLY ENOUGH CONFIDENCE IN SLIGHT CHANCE/CHANCE POPS. && .AVIATION.../18Z TAF ISSUANCE/ TERMINALS WILL BE UNDER THE INFLUENCE OF EXPANSIVE VERTICALLY STACKED AND OCCLUDED LOW NOW NEAR DETROIT THIS ENTIRE TAF PERIOD. FOR THESE TAFS...FAVORED THE RAP HEAVILY...BLENDED A BIT WITH LAMP GUIDANCE. THE 925 MB RAP RH HAS BEEN PERFORMING WELL WITH ERODING OUT WEST END OF MVFR CIGS ACROSS ERN MN. THE RAP HAS BEEN CONSISTENT WITH PUSHING THESE CIGS EAST THROUGH THE MORNING...BEFORE QUICKLY BRINGING THIS MOISTURE SOUTHWEST ACROSS THE REST OF THE MPX CWA THIS AFTERNOON. FOR BRINGING CIGS BACK IN TO RWF/AXN/STC...BLENDED RAP TIMING IN WITH THE SLOWER LAMP GUIDANCE...THOUGH DID FAVOR THE RAP. ONCE THESE CLOUDS MOVE IN...HEIGHTS SHOULD BE FAIRLY CONSISTENT THE REST OF THE TAF PERIOD...WITH NO SIGNS OF SIGNIFICANT CLEARING WORKING INTO THE MPX AREA UNTIL CLOSER TO 00Z...OR LATE THU AFTERNOON. BESIDE CLOUDS...ALSO SEEING A BAND OF MAINLY MVFR SNOW ACROSS CENTRAL WI SLOWLY WORKING WEST. HRRR REFLECTIVITY FORECAST HAS HAD A GOOD HANDLE ON THIS SNOW THIS MORNING...SO FOLLOWED IT FOR TIMING SNOW ACROSS WRN WI. WILL START OFF EAU WITH -SN...WITH THE EXPECTATION THAT SNOW SHOULD BREAK OUT THERE BY 1830Z. MAINLY MVFR VIS RESTRICTIONS ARE EXPECTED...THOUGH WITH THE OCCASIONAL IFR VIS EAST OF EAU...DID KEEP A TEMPO IFR GROUP FOR A BIT THIS AFTERNOON. THIS SNOW WILL LIKELY GRAZE RNH AND STAY SE OF MSP...THOUGH MAY IMPACT FIELD SUCH AS K21D AND KSGS. FOR WINDS...NOT EXPECTING MUCH VARIATION IN DIRECTION THIS PERIOD...WITH JUST AN EVERY SO GRADUAL BACKING TOWARD THE NNW EXPECTED. WILL CONTINUE WITH GUSTS INTO THIS EVENING...BUT THINGS LOOKS TO SETTLE DOWN TONIGHT...WITH NO GUSTS EXPECTED TOMORROW WITH TYPICAL DIURNAL STRENGTHENING. KMSP...RAP HAS BEEN PRETTY CONSISTENT WITH RETURN TO VFR CIGS CURRENTLY OBSERVED. CONFIDENCE IS HIGH WE WILL RETURN TO AROUND 2K FT CIGS..BUT THERE IS LESS CONFIDENCE ON WHEN THEY RETURN...WITH IT POSSIBLY BEING CLOSER TO 00Z BEFORE GOING BACK TO MVFR. IN ADDITION...BAND OF SNOW OUT BY EAU WILL MAKE A RUN FOR MSP...AND BASED ON THE RAP/HRRR...MAY SEE A BRIEF SNOW SHOWER BETWEEN 00Z AND 03Z...THOUGH CONFIDENCE IN THIS HAPPENING NOT HIGH ENOUGH TO INCLUDE IN THE TAF ATTM. OTHER CONCERN THIS TAF PERIOD WILL BE WITH CIG HEIGHTS. KEPT THEM ABOVE 017 FOR NOW...BUT CERTAINLY IS POSSIBLE THAT CIGS COULD DROP TO AROUND 015 LATE TONIGHT INTO THU MORNING. ANY IMPROVEMENTS BACK TO VFR NOT EXPECTED UNTIL NEAR THE END OF OR SHORTLY AFTER THIS TAF PERIOD. /OUTLOOK FOR KMSP/ FRI...VFR WITH MVFR CIGS POSSIBLE. N WIND 5-10 KTS. SAT...VFR. N WIND 5 KTS. SUN...VFR. SE WIND 5 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ CLF/MPG
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
322 PM CST WED FEB 27 2013 .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT 321 PM CST WED FEB 27 2013 AT 3 PM...A LOW PRESSURE SYSTEM WAS LOCATED ACROSS SOUTHERN LOWER MICHIGAN. CYCLONIC FLOW AROUND THIS LOW HAS KEPT CLOUDS AND LIGHT SNOW ACROSS MUCH OF THE FORECAST AREA TODAY. FOR TONIGHT...THE 27.00Z MODELS ARE IN GOOD AGREEMENT THAT A SHORT WAVE ROTATING AROUND THE UPPER LEVEL LOW WILL MOVE WEST SOUTHWEST ACROSS AREA THIS EVENING. THIS SYSTEM WILL PRODUCE AROUND 4 MICROBAR/SEC OF OMEGA BELOW 10K FEET THIS EVENING. THIS LIFT IS CO-LOCATED WITH THE DEEP MOISTURE. THE DEEPEST LIFT IS FOUND ACROSS EASTERN AND SOUTHERN PORTIONS OF THE FORECAST AREA. AS A RESULT...RAISED THE PRECIPITATION PROBABILITIES TO 90 PERCENT IN THESE AREAS. SOUNDINGS ARE COLD ENOUGH THAT THE PRECIPITATION WILL BE IN THE FORM OF SNOW. UNLIKE THIS AFTERNOON WHERE THE SNOW HAD A HARD TIME ACCUMULATING DUE TO THE HIGH SOLAR ANGLE...EXPECT SOME LIGHT ACCUMULATIONS /UP TO A HALF INCH/ TO OCCUR THIS EVENING. WITH CLOUDS REMAINING ACROSS THE REGION AND NO COLD AIR ADVECTION COMING INTO THE AREA...STAYED CLOSE TO THE LOW TEMPERATURES WHICH OCCURRED THIS MORNING. ON THURSDAY...THE CYCLONIC FLOW REMAINS ACROSS THE REGION. THE BUFKIT SOUNDINGS CONTINUE TO SHOW SOME WEAK OMEGA BELOW 5K. DUE TO THIS...INTRODUCED FLURRIES TO THE FORECAST. THIS LIFT MAY BE UNDER DONE IN THE MODELS BECAUSE THERE APPEARS TO BE A WEAK SHORT WAVE IN THE 700 AND 500 MB WIND FIELDS. IF THIS IS THE CASE...THE PRECIPITATION CHANCES WILL LIKELY HAVE TO BE INCREASED. FROM THURSDAY NIGHT INTO FRIDAY NIGHT...HIGH PRESSURE WILL PROVIDE DRY WEATHER. TEMPERATURES WILL AVERAGE A FEW DEGREES BELOW NORMAL. .LONG TERM...SATURDAY THROUGH WEDNESDAY 321 PM CST WED FEB 27 2013 A WEAK TO MODERATE STRATOSPHERIC WARMING EVENT IN THE GULF OF ALASKA WILL HELP THE ARCTIC OSCILLATION TO BECOME INCREASING NEGATIVE /DROPPING TO -4/ THROUGH EARLY NEXT WEEK. AS A RESULT... THE 500 MB FLOW PATTERN WILL BE A POSITIVE PACIFIC NORTH AMERICAN /PNA/ TELECONNECTION. THIS WILL KEEP OUR AREA IN NORTHWEST FLOW THROUGH AT LEAST TUESDAY. THE COLDEST 850 MB ANOMALIES /-3.5 STANDARD DEVIATIONS/ ASSOCIATED WITH THE EASTERN TROUGH WILL BE FOUND ACROSS THE SOUTHEAST UNITED STATES. MEANWHILE IN OUR AREA...THE 850 MB TEMPERATURE ANOMALIES ARE JUST A BIT BELOW NORMAL. FROM MONDAY INTO MONDAY NIGHT...THE 27.12Z GEM...GFS...AND ECMWF ARE COMING TO SOME CONSENSUS THAT A LOW PRESSURE SYSTEM WILL MOVE SOUTHEAST ACROSS THE DAKOTAS AND IOWA. THIS TRACK WOULD BRING SOME SNOW TO THE AREA. THIS SYSTEM HAS BEEN FAIRLY CONSISTENT IN THE GFS FOR THE PAST 3 RUNS. MEANWHILE THE ECMWF HAS SHOWED VERY LITTLE RUN TO RUN CONSISTENCY. DUE TO THE GFS CONSISTENCY... TRENDED THE FORECAST TOWARD IT AND RAISED THE PRECIPITATION PROBABILITIES ABOUT 10 TO 20 PERCENT OVER THE ALL BLEND. BEYOND THIS TIME PERIOD...THE ARE SIGNS IN BOTH THE GFS AND ECMWF THAT THE 500 MB PATTERN WILL MAKE A DRAMATIC SHIFT IN THE 500 MB PATTERN AS A STRONG 500 MB RIDGE DEVELOPS ACROSS THE CENTRAL UNITED STATES. THE ECMWF HAS A MUCH STRONGER RIDGE THAN THE GFS. AS A RESULT...ITS 850 MB TEMPERATURE ANOMALIES ARE STANDARD DEVIATION ARE UP TO 2 ACROSS THE DAKOTAS BY WEDNESDAY. THERE IS ACTUALLY SUPPORT FOR IN THE PACIFIC AS THE MADDEN JULIAN OSCILLATION MOVES FROM PHASE 6 TO PHASE 7. BOTH OF THESE PHASES...SUPPORT WARMTH ACROSS THE EASTERN HALF OF THE CONUS. && .AVIATION...THROUGH 18Z THURSDAY 1142 AM CST WED FEB 27 2013 MAIN AVIATION CONCERNS ARE MVFR CONDITIONS AT BOTH TAF SITES AND BREEZY NORTHERLY WINDS AT RST THROUGH TAF PERIOD. LATEST WATER VAPOR SATELLITE IMAGERY INDICATING SEVERAL SHORTWAVE TROUGHS ROTATING AROUND UPPER LEVEL LOW PRESSURE OVER THE OHIO RIVER VALLEY. THE UPPER LEVEL LOW IS EXPECTED TO CONTINUE TO ROTATE LOW LEVEL MOISTURE INTO THE REGION...ESPECIALLY INTO TONIGHT. LATEST 17Z METARS INDICATE MVFR CONDITIONS AT BOTH RST AND LSE TAF SITES. THE LATEST 27.12Z NAM AND 27.15Z RAP SHOW LOW LEVEL MOISTURE TO SLOWLY DIMINISH OUT OF THE REGION AFTER 12Z THURSDAY. HOWEVER...WITH REGION UNDER THE INFLUENCE OF THE UPPER LEVEL LOW OVER THE OHIO RIVER VALLEY...CONFIDENCE IS NOT VERY HIGH THE TAF SITES WILL COMPLETELY CLEAR OUT OF BROKEN CEILINGS/MVFR CONDITIONS BY 12Z THURSDAY. HAVE KEPT MVFR CONDITIONS THROUGH THE TAF PERIOD. TIGHT PRESSURE GRADIENT ON BACKSIDE OF SURFACE LOW OVER SOUTHERN MICHIGAN WILL ALLOW SUSTAINED WIND SPEEDS OF 15 TO 18 KNOTS AND GUST 20 TO 25 KNOTS AT RST THROUGH 03Z THURSDAY. && .ARX WATCHES/WARNINGS/ADVISORIES... 321 PM CST WED FEB 27 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...DTJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1142 AM CST WED FEB 27 2013 .SHORT TERM... 1142 AM CST WED FEB 27 2013 LATEST RADAR TRENDS HAVE SHOWN SNOW BANDS WEAKENING AND MOVING OUT OF THE ADVISORY AREA. WITH TEMPERATURES WARMING INTO THE LOWER TO MIDDLE 30S OVER THE SOUTHWEST WISCONSIN AND NORTHEAST IOWA...WILL MITIGATE ANY SNOWFALL ACCUMULATION ON ROADWAYS THIS AFTERNOON. THEREFORE...WILL LET THE WINTER WEATHER ADVISORY EXPIRE AT NOON TODAY FOR SOUTHWEST WISCONSIN AND NORTHEAST IOWA. .LONG TERM...SATURDAY THROUGH TUESDAY 306 AM CST WED FEB 27 2013 MEDIUM RANGE MODEL RUNS OF 27.00Z IN REASONABLE AGREEMENT WITH EACH OTHER AND THEIR PREVIOUS RUNS FOR THE AREA TO BE UNDER NORTHWEST TO NORTH FLOW ALOFT THRU THE WEEKEND AND BULK OF ANY SHORTWAVE ENERGY DROPPING THRU THE FLOW REMAINING WEST OF THE AREA. FCST FOR SAT/SUN REMAINS DRY WITH TEMPS A CATEGORY OR TWO BELOW THE NORMALS AS MARCH BEGINS. BETWEEN MODEL CONSISTENCY IMPROVING FOR MON/TUE WITH BREAKDOWN OF THE WESTERN NOAM RIDGE AS A RATHER STRONG SHORTWAVE MOVES THRU THE NORTHERN ROCKIES SUN THEN ACROSS THE CENTRAL PLAINS MON INTO THE MID MS VALLEY TUE. THIS TRENDS SOUTH/WEST WITH THE SHORTWAVE FROM THE EARLIER RUNS. MODEL CONSENSUS CONTINUES A -SN CHANCE ACROSS MUCH OF THE AREA MON INTO TUE BUT CONFIDENCE FOR THIS ON DAYS 6/7 NOT HIGH GIVEN THE TREND/SHIFT OF THE SHORTWAVE ENERGY TO THE SOUTHWEST. IF THE TREND CONTINUES FOR ANOTHER CYCLE...APPEARS MON-TUE WILL NEED TO BE SHIFTED TO A DRY FCST. NOT A LOT OF CONFIDENCE IN THE DAY 6/7 PERIOD AT THIS TIME AND LEFT THE 27.00Z MODEL/ENSEMBLE CONSENSUS DATA IN THE FCST GRIDS AS IS FOR NOW. WITH A SHIFT BACK TO A MORE WESTERLY FLOW FOR EARLY NEXT WEEK...TEMPS RETURNING TO NEAR NORMAL FOR MON/TUE LOOK WELL TRENDED. && .AVIATION...THROUGH 18Z THURSDAY 1142 AM CST WED FEB 27 2013 MAIN AVIATION CONCERNS ARE MVFR CONDITIONS AT BOTH TAF SITES AND BREEZY NORTHERLY WINDS AT RST THROUGH TAF PERIOD. LATEST WATER VAPOR SATELLITE IMAGERY INDICATING SEVERAL SHORTWAVE TROUGHS ROTATING AROUND UPPER LEVEL LOW PRESSURE OVER THE OHIO RIVER VALLEY. THE UPPER LEVEL LOW IS EXPECTED TO CONTINUE TO ROTATE LOW LEVEL MOISTURE INTO THE REGION...ESPECIALLY INTO TONIGHT. LATEST 17Z METARS INDICATE MVFR CONDITIONS AT BOTH RST AND LSE TAF SITES. THE LATEST 27.12Z NAM AND 27.15Z RAP SHOW LOW LEVEL MOISTURE TO SLOWLY DIMINISH OUT OF THE REGION AFTER 12Z THURSDAY. HOWEVER...WITH REGION UNDER THE INFLUENCE OF THE UPPER LEVEL LOW OVER THE OHIO RIVER VALLEY...CONFIDENCE IS NOT VERY HIGH THE TAF SITES WILL COMPLETELY CLEAR OUT OF BROKEN CEILINGS/MVFR CONDITIONS BY 12Z THURSDAY. HAVE KEPT MVFR CONDITIONS THROUGH THE TAF PERIOD. TIGHT PRESSURE GRADIENT ON BACKSIDE OF SURFACE LOW OVER SOUTHERN MICHIGAN WILL ALLOW SUSTAINED WIND SPEEDS OF 15 TO 18 KNOTS AND GUST 20 TO 25 KNOTS AT RST THROUGH 03Z THURSDAY. && .ARX WATCHES/WARNINGS/ADVISORIES... 1142 AM CST WED FEB 27 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DTJ LONG TERM....RRS AVIATION...DTJ