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


AREA FORECAST DISCUSSION
NWS TUCSON AZ
930 AM MST MON FEB 11 2013 .SYNOPSIS...A STRONG AND COLD STORM SYSTEM ACROSS NORTHWEST ARIZONA WILL TRACK ACROSS SOUTHEAST ARIZONA THIS AFTERNOON AND EVENING... RESULTING IN A CHANCE OF VALLEY RAIN AND POSSIBLY LOW ELEVATION SNOWFALL. COLD TEMPERATURES WILL PREVAIL THROUGH TUESDAY FOLLOWED BY DRY CONDITIONS AND A WARMING TREND WEDNESDAY THROUGH SUNDAY. && .DISCUSSION...WATER VAPOR IMAGERY SHOWS AN UPPER LOW OVER PORTIONS OF THE CENTRAL ROCKIES WITH THE TROUGH AXIS EXTENDING SOUTHWEST ACROSS NORTHWEST ARIZONA AND INTO EXTREME SOUTHEAST CALIFORNIA. THE NEXT IMPULSE WITH THIS SYSTEM THAT WILL BRING THE POTENTIAL FOR RAIN AND MOSTLY MOUNTAIN SNOW IS JUST ENTERING WESTERN ARIZONA AT THIS TIME. IR SATELLITE IMAGERY SHOWS A BAND OF EXTENSIVE CLOUDINESS EXTENDING FROM NORTHWEST NEW MEXICO AND ACROSS CENTRAL ARIZONA WITH THE CENTRAL AND EASTERN PORTIONS OF MY FORECAST AREA STILL CLOUD FREE. HOWEVER...TO THE WEST OVER EXTREME WESTERN AND CENTRAL PORTIONS OF PIMA COUNTY...MID LEVEL CLOUDS ARE CONTINUING TO DEVELOP AND THESE WILL MOVE EAST AND SOUTHEAST AS THE MORNING PROGRESSES. THIS MORNINGS KTWC SOUNDING REVEALED A CONTINUED DRY SOUNDING WITH PRECIPITABLE WATER VALUES VIRTUALLY IDENTICAL TO LAST EVENINGS SOUNDING WITH A VALUE THIS MORNING OF 0.19 INCHES. NEEDLESS TO SAY...THE AIRMASS HAS NOT MOISTENED QUITE AS MUCH AS WAS EXPECTED LAST EVENING. THE 00Z NAM SHOWED LESS THAN 10 PERCENT POP FOR THIS AFTERNOON FOR TUCSON...BUT 61 PERCENT POP BETWEEN 00Z AND 06Z THIS EVENING. HOWEVER...THE 12Z RUN OF THE NAM NOW SHOWS 27 PERCENT POP FOR TUCSON THIS AFTERNOON AND VIRTUALLY ZERO AFTER 00Z. IN ADDITION...THE HRRR (HIGH RESOLUTION RAPID REFRESH) MODEL SHOWS A BAND OF PRECIPITATION MOVING ACROSS THE TUCSON METRO AREA BETWEEN AROUND 3 PM TO 6 PM THIS AFTERNOON. THE GFS MOS POP SHOWS ABOUT A 30 PERCENT POP FOR THE MIDDLE TO LATTER PORTION OF THIS AFTERNOON. THE LATEST RADAR MOSAIC AND SURFACE OBSERVATIONS SHOW A BAND OF SHOWERS EXTENDING FROM THE MOGOLLON RIM AREA AND SOUTHWEST ACROSS THE PHOENIX METRO. ANOTHER BATCH OF PRECIPITATION IS MOVING ACROSS THE EXTREME SOUTHWESTERN PORTION OF ARIZONA EAST OF BLYTHE. CLOSER TO HOME...NOT MUCH ACTIVITY OVER MY FORECAST AREA...YET. THAT SAID...THE INHERITED 40 PERCENT POP FOR THIS AFTERNOON SEEMS REASONABLE...SO NO CHANGES ARE PLANNED TO THE POP FORECAST FOR THE REST OF TODAY. HOWEVER...WILL CONTINUE TO MONITOR SATELLITE AND RADAR TRENDS THROUGH THE REMAINDER OF THE MORNING AND INTO THE AFTERNOON AND WILL MAKE ADJUSTMENTS IF NEEDED. INHERITED SNOW AMOUNTS FROM THE NIGHT SHIFT WITH THIS SYSTEM ARE INDICATING AMOUNTS WELL BELOW ADVISORY CRITERIA WITH ABOUT 3 TO 5 INCHES OVER THE WHITE MOUNTAINS AND 2 TO 4 INCHES FOR THE SANTA CATALINA`S OF NORTHEAST PIMA COUNTY AND THE PINALENO`S OF GRAHAM COUNTY. THE TEMPERATURES AS OF 16Z (9 AM MST)...RANGE FROM THE UPPER 30S TO THE LOWER 40S AND THESE READINGS SEEM TO BE ON TRACK WITH EXPECTED AFTERNOON HIGHS...SO NO CHANGES PLANNED AT THIS TIME. && .AVIATION...CLOUDS INCREASING FROM NORTH TO SOUTH ACROSS SOUTHEAST ARIZONA TODAY. EXPECT SCT-BKN CLOUDS AT 5-8K FT AGL DEVELOPING AREAWIDE BETWEEN 11/17Z-11/20Z TODAY. MVFR CIGS/VSBYS AND MOUNTAIN OBSCURATIONS IN SHSN IN THE WHITE MOUNTAINS DEVELOPING AFT 11/17Z WITH SCT VALLEY SHRA/MOUNTAIN SHSN ELSEWHERE. SURFACE WIND LESS THAN 10 KTS THRU 11/14Z...THEN INCREASING SURFACE WIND...WITH SWLY/WLY SURFACE WIND AT 15-20 KTS AND GUSTS TO 20-30 KTS AFT 11/18Z. SURFACE WIND DIMINISHING AFT 12/03Z...AND GENERALLY LESS THAN 10 KTS BY 12/06Z. ELEVATED SURFACE WIND CONTINUING IN THE GILA RIVER VALLEY ON TUESDAY. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...A STORM SYSTEM WILL RESULT IN A CHANCE OF VALLEY RAIN AND MOUNTAIN SNOW SHOWERS TODAY AND TONIGHT...MAINLY FROM TUCSON EAST AND NORTHEAST. THIS SYSTEM WILL ALSO BRING STRONG AND GUSTY WINDS TODAY...CONTINUING IN THE GILA RIVER VALLEY TUESDAY. A WARMING TREND WILL THEN BEGIN ON WEDNESDAY...PERSISTING THROUGH SUNDAY. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS EUREKA CA
347 PM PST TUE FEB 12 2013 .SYNOPSIS...A STRONG AND PERSISTENT RIDGE OF HIGH PRESSURE WILL KEEP NORTHWEST CALIFORNIA DRY THROUGH FRIDAY. HOWEVER COASTAL LOCATIONS WILL SEE PERIODS OF LOW CLOUDS AND FOG THROUGH THURSDAY MORNING. INTERIOR AREAS WILL STAY SUNNY OUTSIDE OF AREAS OF VALLEY FOG. && .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT...A RIDGE OF HIGH PRESSURE CONTINUES TO SIT OFF THE WEST COAST MAINTAINING DEEP NORTHERLY FLOW OVER THE AREA. WEAK SHORTWAVES WILL MOVE SOUTH ALONG THE WEST COAST ON THE EAST SIDE OF THIS RIDGE BRINGING IMPULSES OF INCREASED BOUNDARY LAYER MOISTURE TO COASTAL LOCATIONS PRIMARILY NORTH OF THE CAPE. A FIRST SHORTWAVE IS CURRENTLY MOVING OVER NORTHERN CALIFORNIA...AND HAS RESULTED IN AN EXPANDING FIELD OF STRATUS DEVELOPING FROM ORICK SOUTH TO THE CAPE. EXPECT THIS AREA OF STRATUS TO CONTINUE TO EXPAND THROUGH THE REMAINDER OF THE EVENING AND OVERNIGHT...POSSIBLY STRETCHING NORTH INTO DEL NORTE COUNTY AS ADDITIONAL CLOUDS MOVE SOUTH FROM OFF THE OREGON COAST. A SECOND REINFORCING SHORTWAVE WILL ADVANCE DOWN THE COAST ON THURSDAY WHICH MAY ALLOW CLOUD COVER TO PERSIST ALONG COASTAL AREAS NORTH OF THE CAPE...BUT WITH WEAK OFFSHORE FLOW EXPECTED LATE WEDNESDAY MORNING AND EARLY AFTERNOON...HAVE OPTED TO CONTINUE A FORECAST FOR A SHORT PERIOD OF CLEARING WEDNESDAY FOR ALL AREAS BEFORE THE STRATUS REDEVELOPS WEDNESDAY EVENING. INTERIOR AREAS WILL CONTINUE TO SEE OVERNIGHT AND MORNING FOG...DISSIPATING BY LATE MORNING OR EARLY AFTERNOON. COASTAL CLOUDS WILL BE LESS NUMEROUS SOUTH OF THE CAPE WHERE OFFSHORE FLOW WILL PERSIST...BUT CAN NOT DISCOUNT THE DEVELOPMENT COMPLETELY. AS THE RIDGE BUILDS EAST OVER THE WEST COAST WEDNESDAY NIGHT INTO THURSDAY THE LOW LEVEL INVERSION SHOULD STRENGTHEN AND DESCEND LEADING TO A MORE COMPACT MARINE LAYER AND HIGHER PROBABILITIES OF FOG ALONG THE COAST. BY LATE THURSDAY THE THERMAL TROUGH WILL BEGIN TO MOVE WEST OFF THE COAST AS THE UPPER LEVEL RIDGE MOVES EAST INTO THE PACIFIC NORTHWEST. THIS WILL ENHANCE OFFSHORE FLOW AND LEAD TO CLEARING SKIES. OFFSHORE FLOW LATE THURSDAY AFTERNOON AND AGAIN FRIDAY WILL BRING ABOVE NORMAL TEMPERATURES TO MOST OF NORTHWEST CALIFORNIA WITH 60 DEGREE TEMPERATURES POSSIBLE EVEN ALONG THE IMMEDIATE COAST. THE THERMAL TROUGH WILL THEN SHIFT BACK INLAND LATE FRIDAY AFTERNOON INTO FRIDAY NIGHT WITH RETURN LIGHT SOUTHERLY FLOW POSSIBLY DEVELOPING AHEAD OF AN APPROACHING UPPER TROUGH. IT IS STARTING TO LOOK MORE LIKELY THAT COASTAL CLOUDS MAY RETURN BY LATE FRIDAY AFTERNOON OR OVERNIGHT NORTH OF THE CAPE AS THE SOUTHERLY FLOW DEVELOPS. OTHERWISE DRY AND CLEAR CONDITIONS WILL PERSIST FOR THE REMAINDER OF NORTHWEST CALIFORNIA THROUGH FRIDAY NIGHT. RPA .LONG TERM...SATURDAY THROUGH MID NEXT WEEK...THE SYNOPTIC PATTERN WILL BECOME MUCH MORE PROGRESSIVE HEADING THROUGH THIS WEEKEND. THE PERSISTENT RIDGE OVER THE EASTERN PACIFIC WILL GIVE WAY TO A SERIES OF STORM SYSTEMS TRACKING FROM THE ALEUTIANS TO THE GULF OF ALASKA...AND EVENTUALLY IMPACTING THE PACIFIC NORTHWEST. THE FIRST SUCH SYSTEM WILL TRACK WELL TO OUR NORTH WITH PERHAPS JUST THE SOUTHERN END OF ITS COLD FRONT CLIPPING NORTHWEST CALIFORNIA LATE SATURDAY. MODELS ARE COMING INTO BETTER AGREEMENT AND SEEM TO BE SETTLING ON THIS SOLUTION...WHICH WOULD MEAN JUST A COUPLE OF SHOWERS FOR THE NORTH COAST SATURDAY AFTERNOON. THIS COULD LINGER INTO SATURDAY NIGHT BUT AT THIS POINT SUNDAY IS LOOKING MOSTLY DRY AND SUNNY ALBEIT A BIT COOLER. ANOTHER SHORTWAVE MAY PASS THROUGH LATE MONDAY WITH SIMILAR IMPACT BUT SLIGHTLY MORE MOISTURE...AHEAD OF A MORE SIGNIFICANT SYSTEM SET TO IMPACT NORTHWEST CALIFORNIA TUESDAY. THIS STORM COULD BRING RELATIVELY LOW SNOW LEVELS AND COLDER TEMPERATURES ALONG WITH A GOOD CHANCE OF RAIN AND HAIL SHOWERS AT THE COAST. AAD && .AVIATION...MORE MOISTURE POOLING OCCURRING ON WINDWARD SIDE OF CAPE MENDOCINO GENERALLY ALONG THE COAST WITH PERSISTENT N WINDS PUSHING THE LOW CLOUDS AND FOG DOWNWIND WELL PAST THE CAPE AND FARTHER OFFSHORE. DOWNSLOPING N OF KACV IS KEEPING THAT TERMINAL MOSTLY CLEAR FOR NOW. EXPECT AS LAND-BASED WINDS DECREASE THIS EVENING... SCT TO PERHAPS BKN LOW CLOUDS MAY FILL IN THERE. BOTH THE NAM AND THE RUC HAVE BECOME MORE BULLISH WITH REDUCED VSBYS LATER TONIGHT AT KACV. FOR NOW...HAVE KEPT MINIMUM VSBYS AT 4SM WITH CIGS BETWEEN 04Z AND 15Z. A MODERATE TO HIGH LEVEL OF UNCERTAINTY EXISTS WITH THIS FORECAST. HAVE KEPT KCEC AS VFR OVERNIGHT WITH A HINT OF LOW CLOUDINESS AND LIGHT FOG. THIS WILL NEED TO BE MONITORED CLOSELY. /SEC && .MARINE...LITTLE TO CHANGE WITH EXISTING FORECAST PACKAGE. N WINDS HAVE DIMINISHED IN THE PAST 24 HRS...BUT SMALL CRAFT ADVISORY CONDITIONS CONTINUE IN ALL BUT THE NEAR SHORE S LEG. EVEN THERE... WIND GUSTS TO 30 KTS REMAIN POSSIBLE THRU THE EVENING DOWNWIND FROM PROMINENT CAPES. WINDS WILL INCREASE AGAIN WED NIGHT...THEN DECREASE AGAIN BY LATE IN THE WORK WEEK. PRESENT LONG PERIOD WAVE GROUP WILL CONTINUE TO DECAY THRU WED. FORERUNNERS FROM ANOTHER WAVE GROUP WILL ENTER THE AREA LATE WED WITH WAVES BUILDING AND PERIODS DECREASING INTO LATE WEEK. A 3RD WAVE TRAIN WILL ARRIVE LATE FRI OR EARLY SAT. /SEC && .EKA WATCHES/WARNINGS/ADVISORIES... CA...NONE. NORTHWEST CALIFORNIA COASTAL WATERS... SMALL CRAFT ADVISORY UNTIL 9 PM PST THIS EVENING PZZ450. SMALL CRAFT ADVISORY UNTIL 3 AM PST WEDNESDAY PZZ470. SMALL CRAFT ADVISORY UNTIL 9 AM PST FRIDAY PZZ475. && $$ VISIT US AT HTTP://WWW.WEATHER.GOV/EUREKA FOLLOW US ON FACEBOOK AND TWITTER AT: HTTP://WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.EUREKA.GOV HTTP://WWW.TWITTER.COM/NWSEUREKA
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
607 AM MST MON FEB 11 2013 .UPDATE... ISSUED AT 602 AM MST MON FEB 11 2013 NICELY WOUND UP LOW/VORTICITY CENTER HAS STARTED TO SHEER APART PER LATEST SATELLITE IMAGERY AND SHOWING SIGNS OF THIS ON LATEST RADAR RETURNS AS WELL. LATEST 3KM HRRR REFLECTIVITY FORECAST GRABBING ONTO THIS AND INDICATING THE EARLIER BAND OF HEAVIER SNOWFALL RESPONSIBLE FOR 2 INCHES OF SNOW IN THE GRAND VALLEY AND NUCLA REGIONS WILL BE TRENDING DOWN...WITH SNOW SHOWERS BECOMING MORE SCATTERED IN NATURE FOR AREAS ALONG AND NORTH OF INTERSTATE 70. AS A RESULT...HAVE WENT AHEAD AND ALLOWED THE WINTER STORM WARNINGS EXPIRE FOR THESE AREAS AS OF 6 AM MST. STILL SHOULD SEE ANOTHER INCH OR TWO IN A FEW AREAS...BUT OVERALL COVERAGE WILL BE DIMINISHED. AWAITING SUNRISE BEFORE MAKING FINAL CALL ON OTHER HIGHLIGHTS...ALTHOUGH IR IMAGERY SUGGESTS WE MAY BE MAKING MORE ADJUSTMENTS TO SOUTHERN HIGHLIGHTS AS THE DAY WEARS ON. && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 326 AM MST MON FEB 11 2013 MESSY FORECAST SITUATION THIS WITH QUICKLY CHANGING CONDITIONS ACROSS THE REGION. THE 700-600MB LOW...THAT IS KEY TO THE HIGHLIGHTS IN THE FOUR CORNERS ZONES...WAS PROGGED DIFFERENTLY TONIGHT. IT IS SITUATED FURTHER NORTH THAN PREVIOUSLY PROGGED. IT SPUN NEAR CANYONLANDS NATIONAL PARK THROUGH MUCH OF THE NIGHT AND WILL PROGRESS SOUTH OF THE I-70 CORRIDOR TODAY. ON THE WEST EDGE OF THE ASSOCIATED BAROCLINIC LEAF...VERY HEAVY SNOW BANDS HAVE FORMED. IN NUCLA AND GRAND JUNCTION TWO INCHES FELL IN JUST OVER ONE HOUR WITH VISIBILITY DOWN TO 1/4 MILE. THIS AREA OF HEAVY SNOW WILL MARCH EAST DOWN THE I-70 CORRIDOR THIS MORNING REACHING RIFLE AROUND 5 AM... GLENWOOD SPRINGS TO ASPEN AROUND 7 AM AND EAGLE AROUND 8 AM. ENHANCED CLOUD TOPS ARE SPREADING BACK ACROSS THE NW COLORADO ZONES WHERE LIGHT SNOWFALL WILL CONTINUE THIS MORNING. HIGHLIGHTS WILL LIKELY COME DOWN AT 6 AM AS CURRENTLY TIMED BUT ANOTHER 2-4 INCHES MAY FALL IN THE NORTHERN MTNS TODAY. FURTHER SOUTH...TIGHT LOW LEVEL CYCLONIC ROTATION AND FAVORABLE SOUTHWEST FLOW OROGRAPHICS WILL CONTINUE TO PRODUCE ACCUMULATING SNOW FOR SOUTHEAST UTAH AND SOUTHWEST COLORADO. SNOW AMOUNTS THERE WILL LIKELY BE CLOSER TO 3-6 INCHES IN CEZ-DRO-PSO VALLEYS. THE MID LEVEL LOW SHIFTS EAST OF THE CONTINENTAL DIVIDE LATE THIS AFTERNOON AND THE LAST SNOW SHOWERS OF THIS STORM END BY MIDNIGHT. A COLD NIGHT EXPECTED MONDAY NIGHT UNDER CLEARING SKIES...LIGHT NORTH WINDS...AND 700MB TEMPS AT -14C. AREAS OF FREEZING FOG ARE POSSIBLE. TUESDAY...A TRANSIENT RIDGE PASSES FROM NORTH TO SOUTH PRODUCING WARM ADVECTION ALOFT AND CAPPED VALLEYS. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 326 AM MST MON FEB 11 2013 DIRTY NORTH TO NORTHWEST FLOW ALOFT WILL BE SETTING UP OVER THE FORECAST AREA TUESDAY NIGHT AND PERSIST THROUGH THE END OF THE WEEK. THIS WILL BRING A FEW ROUNDS OF SNOW TO THE NORTHERN AND CENTRAL MOUNTAINS...GENERALLY FROM VAIL PASS NORTHWARD...AS WEAK WAVES PUSH THROUGH. THE STRONGEST IN THIS SERIES ARRIVES WEDNESDAY NIGHT AND THURSDAY...AND HAVE BOOSTED POPS UP INTO THE LOW LIKELY CATEGORIES FOR THE FLAT TOPS AND THE PARK RANGE. THIS WAVE WILL DRIVE THE MOISTURE A BIT FURTHER SOUTH...IMPACTING THE SAN JUANS AS WELL...BUT MODELS HAVE BEEN TRENDING WEAKER WITH EACH RUN...SO WILL NOT JUMP POPS UP MUCH AT THIS TIME. HEIGHTS START CLIMBING BY FRIDAY AFTERNOON...WITH DRY CONDITIONS EXPECTED AS WE WORK INTO THE WEEKEND. TEMPERATURES WILL BE RUNNING COOLER THAN NORMAL THIS WEEK...WITH GRADUAL WARMING INTO THE WEEKEND. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 326 AM MST MON FEB 11 2013 ACROSS THE NORTH INCLUDING KVEL KCAG KHDN KSBS SCATTERED SNOW SHOWERS WILL PRODUCE BRIEF MVFR CEILINGS THROUGH 21Z. OTHERWISE VFR CONDITIONS WILL DOMINATE. WIDESPREAD FOG MAY PERSIST IN THE VCNTY OF KVEL UNTIL 18Z. AND VALLEY FOG IS POSSIBLE AFTER 06Z TONIGHT FURTHER SOUTH SNOW SHOWERS WILL BE WIDESPREAD THROUGH THIS AFTERNOON. MOUNTAIN OBSCURATIONS WITH POOR FLIGHT CONDITIONS WILL BE WIDESPREAD OVER THE SOUTHERN MOUNTAINS AND OCCASIONAL OVER THE CENTRAL MOUNTAINS. LOW CEILINGS WILL PRODUCE MVFR/IFR CONDITIONS AT TIMES OVER THE SOUTHERN AIRPORTS INCLUDING KCEZ KDRO KPSO. THESE TAF SITES MAY BE IMPACTED AT TIMES WITH MVFR AND POSSIBLY EVEN BRIEF IFR CONDITIONS IN SNOW SHOWERS...LOW CLOUDS AND/OR FOG. KRIL KASE KEGE WILL HAVE 1-2 HOURS OF LIFR CONDITIONS IN HEAVY SNOW THIS MORNING BETWEEN 12-15Z. TAF SITES WILL SEE A DECREASING CHANCE OF SNOW THIS AFTERNOON WITH VFR CONDITIONS EXPECTED FOR ALL TAF SITES AFTER 06Z TONIGHT. AREAS OF VALLEY FOG ARE POSSIBLE AFTER 06Z TONIGHT. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER STORM WARNING UNTIL MIDNIGHT MST TONIGHT FOR COZ018-019- 021>023. WINTER STORM WARNING UNTIL NOON MST TODAY FOR COZ009-012-017. UT...WINTER STORM WARNING UNTIL NOON MST TODAY FOR UTZ028. WINTER WEATHER ADVISORY UNTIL 6 PM MST THIS EVENING FOR UTZ022- 029. && $$ UPDATE...JDC SHORT TERM...JOE LONG TERM...JDC AVIATION...JOE
AREA FORECAST DISCUSSION
NWS TAUNTON MA
701 PM EST TUE FEB 12 2013 .SYNOPSIS... BLUSTERY WEST WINDS DIMINISH TONIGHT. DRY WEATHER PREVAILS THROUGH WEDNESDAY WITH SEASONABLE TEMPERATURES. A QUICK MOVING OCEAN STORM MAY BRING MINOR SNOW ACCUMULATIONS WEDNESDAY NIGHT TO THE SOUTH COAST OF MASSACHUSETTS AND RHODE ISLAND...INCLUDING CAPE COD AND THE ISLANDS. A CLIPPER LOW MAY BRING SNOW SHOWERS SAT. BLUSTERY AND UNSEASONABLY COLD WEATHER FOLLOWS SUNDAY INTO MONDAY. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 7 PM UPDATE... WV IMAGERY SHOWS WEAK FAST MOVING SHORTWAVE MOVING THROUGH NY WHICH IS EXPECTED TO CROSS THE REGION DURING THE EARLY HALF OF THE OVERNIGHT. THIS MAY HELP REINFORCE SOME OF THE MID LVL COLD ADVECTION...MAINTAINING THE SC FIELD AND KEEPING THE WINDS SOMEWHAT ELEVATED. HOWEVER...GIVEN THE LACK OF SUNSHINE...WINDS/CLOUDS STILL GENERALLY DIMINISH SOMEWHAT...ACCELERATING MORE-SO AFTER ABOUT 06Z /1 AM/ AS THE WAVE MOVES E. HAVE TRENDED SKIES/WIND FORECAST FOR THE OVERNIGHT TOWARD THIS THINKING/TIMING. RAP WAS USED AS A BASELINE AS IT SEEMED TO FIT THIS IDEA. ALSO ADJUSTED TEMPS/DWPTS TO BRING THEM UP TO TRENDS. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... WEDNESDAY... SUFFICIENT SHORT WAVE RIDGING OVER THE REGION FOR AT LEAST PARTIAL SUNSHINE. WILL LIKELY SEE SOME MID/HIGH WAA CLOUDS ARRIVE ON THE SW HORIZON AS MID LEVEL TROUGH APPROACHES. FAIRLY NICE DAY BY MID FEB STANDARDS WITH SUNSHINE/TEMPS 35-40 AND LIGHT WINDS. WED NIGHT... 12Z MODEL GUIDANCE HAS TRENDED FARTHER OFFSHORE WITH SHORT WAVE TROUGH AND ASSOCIATED SURFACE LOW. THE EXCEPTION IS THE NAM WHICH IS MORE ROBUST WITH ITS MID LEVEL TROUGH WHICH RESULTS IN MORE SHORT WAVE RIDGING...YIELDING A MORE NORTHWARD SOLUTION. A POSSIBLE RED FLAG FOR THE 12Z NAM IS THE NEW 15Z SREF WHICH SUPPORTS THE MORE SOUTHERN SOLUTION OF THE EC. THE ECMWF HAS SHOWN GREAT RUN TO RUN CONSISTENCY SO WE FOLLOWED ITS SOLUTION FOR THIS FORECAST. THIS RESULTS IN SNOW ACCUMULATIONS CONFINED TO THE SOUTH COAST OF MA AND RI INCLUDING CAPE COD AND THE ISLANDS. CURRENT THINKING 1-2 INCHES ACROSS THIS AREA WITH LESS THAN AN INCH ACROSS NORTHERN PORTIONS OF CT/RI INTO INTERIOR SOUTHEAST MA. LITTLE IF ANY ACCUMULATION NORTH OF THE MA PIKE. WE WILL HAVE TO WATCH LATER RUNS FOR A POSSIBLE FARTHER OFFSHORE TRACK WHICH WOULD YIELD LITTLE IF ANY SNOW ACCUMULATIONS ANYWHERE INCLUDING THE SOUTH COAST. && .LONG TERM /THURSDAY THROUGH TUESDAY/... HEADLINES... * CLIPPER LOW MAY BRING SOME LIGHT SNOW TO THE REGION SATURDAY * DEVELOPING OFFSHORE LOOKS TO REMAIN OFFSHORE SAT/SUN * COLDER AIR BUILDS ACROSS THE REGION FOR THE EARLY PART OF NEXT WEEK * A RETURN TO MILDER CONDITIONS IS POSSIBLE BY MIDWEEK OVERVIEW AND MODEL PREFERENCES... GIVEN THE MODEL SPREAD ON THE CPC TELECONNECTIONS...MODELS MAY BE STRUGGLING WITH A LATE WEAK SHIFT TO VERY MERIDIONAL FLOW WITH BROAD DEEP TROF SETTLING OVER THE GREAT LAKES TO NEW ENGLAND AND VERY STRING RIDGING OFFSHORE. NONETHELESS...12/12Z ECMWF STILL VERY CONSISTENT IN ITS SYNOPTIC PATTERN AS IT HAS BEEN FOR SEVERAL RUNS NOW. INDEED...EVEN THE SLIGHTLY MORE PROGRESSIVE 12/12Z GFS IS GRADUALLY TRENDING TOWARD THE ECMWF SOLUTION WITH EVERY RUN. WITH THIS IN MIND...LIKE THE PREVIOUS SHIFT/S THINKING IN LEANING TOWARD A ECMWF SOLUTION. WILL CONTINUE THIS TREND FOR THIS UPDATE DESPITE THE METEOROLOGICAL SQUEEZE PLAY OVER SRN NEW ENGLAND BETWEEN THE STRONG TROF AND RIDGE AND THE MODEL SPREAD REGARDING IT. DETAILS... THU INTO FRI... MOSTLY DRY AFTER EARLY MORNING SNOW OVER SRN PORTIONS OF THE FORECAST AREA SHIFTS S BY MID DAY THU. THIS TREND TOWARD DRYING IS THANKS TO WEAK MID LVL RIDGING IN ADVANCE OF THE DIGGING LONGWAVE TROF TO THE W. THEREFORE...DESPITE A COOL START WITH N-NW FLOW THE GRADUAL TREND WILL BE TOWARD WARMING INTO FRI AS SW FLOW SETS UP E OF THE TROF. MAYBE AN ISOLATED -SHSN/SHRA LATE FRI WITH A WEAK WARM FRONTAL PASSAGE...BUT SOUNDINGS REMAIN QUITE DRY SO WILL CONTINUE WITH THIS THINKING. FRI NIGHT INTO SAT... CLIPPER SYSTEM PASSES WELL NW OF THE REGION. AS PREVIOUS SHIFT NOTED...CLIMATOLOGICAL THIS IS THE UNFAVORABLE CLIPPER TRACK FOR PRECIPITATION...AND THIS ENHANCED BY AN ALREADY DRY COLUMN. THEREFORE...WILL ERR TOWARD ONLY SLIGHT TO CHANCE POPS WITH COLD FROPA ASSOCIATED WITH THIS LOW EARLY SAT...BUT THERE IS THE CHANCE IT COULD REMAIN MOSTLY DRY EVERYWHERE. SUN INTO MON... ONE ENHANCEMENT THIS COLD FRONT WILL LEAD TO HOWEVER...IS USHERING IN A MUCH COLDER AIRMASS. H5 HEIGHTS DROP SIGNIFICANTLY TO ABOUT 520 DM OR LOWER WITH H85 TEMPS IN THE -15 TO -20C RANGE. THEREFORE A BRIEF COLD SNAP AS THE LONGWAVE TROF SLOWLY SHIFTS OVER THANKS TO A WEAKENING OF THE ATLANTIC RIDGE. GIVEN THIS SHIFT...SUSPECT THAT ECMWF SUGGESTION THAT LOW PRES REMAINS WELL OFFSHORE SUN REMAINS A BETTER FORECAST...AND WILL CONTINUE WITH A MOSTLY DRY FORECAST WITH STRONG HIGH PRES AND COOL AIRMASS. TUE INTO WED... A FAIR AMOUNT OF UNCERTAINTY HERE...BUT WITH LONGWAVE TROF SHIFTING E AND GRADUALLY OPENING...GUIDANCE FAVORS BROAD RIDGE BUILDING OVER THE ERN CONUS WITH A WARMING TREND. GUIDANCE ALSO TRYING TO BRING A VERY ROBUST LOW PRES INTO THE ST. LAWRENCE VALLEY BY TUE NIGHT...BUT GIVEN THE UNCERTAINTY WILL KEEP ANY POPS LOW. && .AVIATION /23Z TUESDAY THROUGH SUNDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW...HIGH CONFIDENCE THE DAY TOMORROW...LOWER CONFIDENCE IN WED NIGHT. GENERALLY VFR SAVE FOR SOME TERMINALS IN HIGHER TERRAIN /LIKE ORH/ WHICH MAY DIP TO BRIEF MVFR CIGS UNTIL THE STRATO-CU CLEARS OVER THE NEXT FEW HOURS. WINDS ALSO GRADUALLY SUBSIDE OUT OF THE WNW OVERNIGHT. BECOMING LIGHT /BELOW 10 KT/ PRETTY MUCH EVERYWHERE BY 12Z WED. KBOS TAF...HIGH CONFIDENCE. VFR. KBDL TAF...HIGH CONFIDENCE. VFR. OUTLOOK...THURSDAY THROUGH SUNDAY... THU THROUGH FRI...HIGH CONFIDENCE. VFR AFTER ANY SNOW OVER S COASTAL TERMINALS MOVES OUT. SAT...MODERATE CONFIDENCE. COLD FRONTAL PASSAGE WITH SOME -SHSN AND POSSIBLE MVFR. MOSTLY VFR HOWEVER. SUN...MODERATE TO HIGH CONFIDENCE. MOSTLY VFR. && .MARINE... HIGH FORECAST CONFIDENCE THROUGH WED NIGHT. TONIGHT... GUSTY WEST WINDS SLOWLY EASE. OTHERWISE DRY WEATHER WITH GOOD VSBY. WED... WINDS DIMINISH AS HIGH PRES BUILDS OVER THE NE. VSBY REMAINS GOOD ALONG WITH DRY WEATHER. WED NIGHT... SNOW OVERSPREADS THE SOUTHERN WATERS WITH VSBY 1-3 MILES. SNOW TAPERS OFF NORTH OF CAPE COD BAY TO MA BAY. OCEAN LOW TRACKS SOUTH OF 40N/70W...SO NE WINDS WILL REMAIN SUBGALE. OUTLOOK...THURSDAY THROUGH SATURDAY... THU INTO THU NIGHT...HIGH CONFIDENCE. WINDS AND SEAS GRADUALLY DROP TO BELOW SMALL CRAFT ADVISORY THRESHOLDS THROUGH THE DAY AND REMAIN BELOW OVERNIGHT. FRI INTO SAT...MODERATE. LOW PRES PASSES WELL N OF THE WATERS WITH A COLD FRONTAL PASSAGE EXPECTED. MAY SEE BOTH WINDS AND SEAS REACH SMALL CRAFT ADVISORY LEVELS BY FRI...CONTINUING THROUGH SAT. SUN...MODERATE CONFIDENCE. NW WINDS HAVE THE CHANCE OF APPROACHING GALE FORCE SUN. OTHERWISE...SMALL CRAFT ADVISORIES ARE LIKELY TO CONTINUE. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST WEDNESDAY FOR ANZ231>235- 237-251. SMALL CRAFT ADVISORY UNTIL 2 AM EST WEDNESDAY FOR ANZ230-236. SMALL CRAFT ADVISORY UNTIL 1 PM EST WEDNESDAY FOR ANZ250- 254>256. && $$ SYNOPSIS...NOCERA/DOODY NEAR TERM...NOCERA/DOODY SHORT TERM...NOCERA LONG TERM...DOODY AVIATION...NOCERA/DOODY MARINE...NOCERA/DOODY
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
354 PM EST Mon Feb 11 2013 .NEAR TERM [through Tonight]... Thunderstorms continue as of 20 UTC along an outflow boundary that stretched from Fitzgerald, GA (FZG) to Bainbridge, GA (BGE) to Destin, FL (DTS). This outflow boundary has not moved much during the course of the day, likely due to largely boundary-parallel flow in the lowest 2km AGL. Meanwhile, GOES blended PWAT product shows a broad ribbon of 1.2 to 1.5" values near and just behind the slow-moving boundary - roughly 150-250% of normal across much of the Gulf coast and into the Carolinas. These ingredients taken together are favorable for flash flooding events due to training thunderstorms. As such, it is not surprising that we have had some flash flooding today - see the "Hydrology" section below for more information. The overall atmospheric pattern is not expected to change much overnight. The outflow boundary / deep convergence zone should shift gradually south into the evening hours, which should focus the majority of the thunderstorm activity in our area from 22-06z from around PAM-TVI. Meanwhile, a large area of moderate rain with embedded thunderstorms was developing from C/S AL west into LA. This area of rain was roughly on the broad nose of a newly developed low-level moisture transport maximum - currently focused into coastal Louisiana and Mississippi. The RAP projects that the ribbon of strongest moisture transport should develop northeast into our area by around 03z, with roughly similar PWAT values. Therefore, we anticipate that rain - heavy at times, with embedded storms - will redevelop across much of the NW half to two-thirds of our area this evening. Parts of our area remain in a "Slight Risk" of severe storms as of the 20 UTC SPC SWODY1. An isolated severe storm cannot be ruled out with some marginal mixed layer instability and effective shear around 45 knots lingering into the evening. && .SHORT TERM [Tuesday through Wednesday Night]... A more pronounced mid-upper level trough - currently evident on water vapor loops over the Desert Southwest - will dig ESE into the Southern Plains on Tuesday, and then eject into the Ohio River Valley on Tuesday Night. This evolution will allow for surface cyclogenesis on Tuesday near coastal Louisiana, with the low passing northwest of our area through central Alabama on Tuesday Night. With stronger height falls and QG convergence to the west of us on Tuesday, we should see a lull in the rain during the day. The better chances of rain are expected to arrive from Tuesday Night into Wednesday with the main trailing cold front. Portions of our area are in a "Slight Risk" on the latest SPC SWODY2 outlook for the possibility of storms moving in later in the period (Tuesday evening or overnight). The local confidence grids and the SPC SREF calibrated severe probabilities both indicate about a 15-20% chance of severe storms in the western two-thirds of our area in the 12-hour period centered on 12z Wednesday. CIPS analogs from SLU show about 5-10% probabilities, with about half the analogs with at least one severe weather report in our area. The combination of all of these probabilistic outlooks are in fairly good agreement, and are consistent with some isolated severe storms late Tuesday Night. Mean model MLCAPE on the ECMWF, GFS, and CAM models looks to be around 500 j/kg overnight with about 60-70 knots of deep layer shear. && .LONG TERM [Thursday through Monday]... Quieter weather arrives with surface high pressure and increasing subsidence in the wake of the cold front on Thursday and Friday. An amplifying longwave trough in the eastern CONUS on the weekend may provide a shot of colder air, although details still vary from model-to-model, and run-to-run. && .AVIATION [through 18z Tuesday]... Complex forecast for all TAF sites through the period with unsettled weather ahead of a slow moving surface front. Scattered to numerous showers and thunderstorms will be common around the area with MVFR most prevalent. Occasional IFR conditions will accompany the stronger storms through the evening, with MVFR and IFR prevailing overnight due to cigs and vsby near or below airport minimums. A repeat tomorrow, with perhaps more widespread showers and thunderstorms late in the day. && .MARINE... Unsettled weather pattern will remain through mid week with a chance of showers and thunderstorms, as well as breezy southerly winds each period. Winds will increase a bit ahead of a cold front Tuesday night and Wednesday, before switching to offshore on Thursday and diminishing into the weekend. && .FIRE WEATHER... An unsettled weather pattern with scattered to numerous showers and thunderstorms will continue at least through Wednesday. Drier conditions will return late in the week but we see no fire weather concerns at this time. && .HYDROLOGY... Significant rainfall has largely ended for this afternoon across the region. Observed and radar estimated rainfall totals show significant storm totals of 10 to 15 inches from Central Geneva County eastward through much of Houston County. Lower values of 5 to 8 inches were observed further east into parts of Southwestern Georgia in the last 24 hours. Given recent rains across Southeast Alabama and Southwest Georgia, little additional rainfall will be needed to cause flash flooding in these areas and a flash flood watch remains in effect through Tuesday morning. Higher end rainfall totals are expected once again on Tuesday evening through Wednesday across the area. Given the uncertainty with the exact placement of the heaviest rainfall with this next system, will delay any flash flood watches on this package. However, it is expected that additional flash flood watches will be needed across the area Tuesday night into Wednesday. Riverine flooding will become an increasing concern as local runoff is routed downstream from creeks and streams in Southeast Alabama. River gages north of a line from Enterprise Alabama to Abbeville Alabama appear to have crested with routed flow from these sites progressing down into the Choctawhatchee River system. Rises to near or in excess of minor flood stage is anticipated along the Choctawhatchee River from Geneva southward to Caryville into Friday given the current water already in the system. Flooding may also continue downriver toward Bruce but this would not occur until Saturday under present conditions. Rises on the Chipola River to minor flood stage can also be expected later this week as runoff progresses downstream from Southern Alabama. Additional riverine flooding, both in magnitude and coverage, will largely depend on the next 36 to 48 hours worth of rainfall. With soils already saturated in Southeast Alabama and a good portion of Southern Georgia, little additional rainfall will be absorbed there and will thus be converted into runoff, increasing river flood potential. River systems in South Central Georgia and the Florida Big Bend still have plenty of capacity and riverine flooding is not anticipated in these areas with this system. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 59 71 62 70 44 / 70 50 80 80 20 Panama City 60 71 62 66 46 / 80 50 80 70 20 Dothan 54 64 58 64 40 / 80 80 90 70 20 Albany 53 65 58 66 40 / 80 70 90 80 20 Valdosta 56 71 60 71 44 / 60 50 80 80 30 Cross City 61 77 61 74 48 / 20 30 60 70 30 Apalachicola 62 70 64 68 48 / 60 40 70 80 30 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...FLASH FLOOD WATCH through 6 AM CST Tuesday for Central Walton-Holmes-Inland Walton-Jackson-Washington. GA...FLASH FLOOD WATCH through 7 AM EST Tuesday for Baker-Ben Hill-Calhoun-Clay-Dougherty-Early-Irwin-Lee-Miller-Quitman- Randolph-Seminole-Terrell-Tift-Turner-Worth. AL...FLASH FLOOD WATCH through 6 AM CST Tuesday for Coffee-Dale- Geneva-Henry-Houston. GM...None. && $$ DISCUSSION...Lamers AVIATION...Evans MARINE...Evans FIRE WEATHER...Barry HYDROLOGY...Godsey
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
930 AM EST Mon Feb 11 2013 .MESOSCALE UPDATE [through this Afternoon]... Numerous showers and thunderstorms continue to develop along a composite outflow boundary from near the Alabama-Florida border ENE towards Albany, GA (KABY). The outflow boundary roughly establishes the southward extent of a shallow cold pool that developed due to abundant overnight convection. The cold pool appears to be about 2000 feet deep examining the BMX 12z sounding. 13z SPC mesoanalysis (objective RUC analysis) indicates an elongated area of deep moisture convergence along the outflow boundary, with a maximum in west-southwesterly low-level moisture transport centered right over SE Alabama. These moisture transport vectors, and thus the LLJ are close to being boundary-parallel, which from a pattern recognition standpoint is a classic setup for flash flooding. Given recent reports with rainfall totals as high as 8 inches in some of our SE Alabama zones, and the likelihood of additional heavy rainfall through the day, we are becoming increasingly concerned about a significant flash flooding event in those areas. One additional concern is whether or not training echoes will develop south with time - more into the I-10 corridor of the Florida Panhandle. The HRRR supports this idea by afternoon, and therefore the next decision to be made with respect to the Flash Flood Watch will be whether or not to expand it south. Once a decision is made (prior to 1530z) regarding additional expansion of the FFA, we will likely ratchet up the wording in both the existing portion of the FFA (where flooding is already occurring) as well as the HWO. There will still be the potential for isolated severe thunderstorms, as mesoanalysis shows around 1000 j/kg of MLCAPE with around 50 knots of effective shear. However, the best severe weather potential would probably be in the warm sector away from the training storms that are anchored near the outflow boundary. && .NEAR TERM [Tonight]... With front sagging towards N FL tonight and likely stalling, it will be a wet night however there should be a lull in development of storms as we will be in relatively more stable air. may be some fog development ahead of boundary. && .SHORT TERM [Tuesday Through Wednesday]... The large scale long wave pattern commence with a trough over NE states and adjacent Canada with axis down ern seaboard and another trough over Central and srn plains with low developing over TX. Upper high anchored over Srn Gulf of Mex. At surface, low Canadian Maritimes with cold front SSW down extreme wrn Atlc remaining quasi-stnry across fl portion of CWA and into nrn gulf of Mex as it gets caught in the upper level SW flow ahead of upstream trough. With several impulses moving rapidly thru SE region in strong divergent WSW mid/upper flow downstream of upper trough/low, the primary concern will be locally heavy rainfall through the period. During Tuesday, the Ern low will move across New England while Plains low likely opens up into a wave late TUES night. At surface, low forms in Srn Plains and then moves ENE along Nrn Gulf to LA Tues eve then inland to Srn AL at night with cold front lifting NWD back i-10 corridor then to GA/AL border. Initially this translates to increasing overrunning/isentropic lift spreading ewd. As low lifts further newd, front dragged back SEWD across our area. As far as severe wx, best shot will be Tues night. The proximity of the surface low and proximity of front and upper features will favor a strongly sheared environment. Key factor is where front actually sets up. As SPC noted limiting factor may be development of multiple thunderstorm clusters which would retard nwd movement of MT airmass so best chances for strong to severe convection will be near Panhandle coast where dew points in the mid-upper 60s are forecast. North of front, more elevated tstms would favor hail while south of front with strong deep layer shear, more surface based storms with super cells/damaging wind and even an isold tornado cant be discounted. GFS and Nam both show 0-6 KM shear of near 70 kt over SE AL and 60kt over Panhandle at 12z Wed. SPC has placed area in 5% severe prob for Tues night and suspect this will be raised before Tues night. On Wed morning, low across Central GA with cold front bisecting CWA. Several shortwaves move across region to push front SEWD. pops remain especially on high side to begin the day. Chance of strong to isold severe storms remain especially in warm sector where deep shear will battle limited buoyancy for control. By end of period, low races newd, cold front dragged SEWD of CWA with drier air beginning to enter NW third of CWA. Total STP rainfall amounts through Wed could easily average 3 to 4 inches with isolated 5 inches totals especially Nrn tier counties so flooding concerns will be closely monitored. && .LONG TERM [Wednesday Night through Sunday]... The long term forecast is now a little more uncertain due to the slower progression of the upper level system seen in the 12z model cycle. The 00z Euro was weighted heavier in today`s long term forecast, so should the slower progression of the 12z GFS pan out, unsettled weather could continue into Thursday before the Eastern CONUS pattern amplifies enough to kick out the frontal boundary that had been in place across the region. Model guidance, however, is in reasonably good agreement, that with the amplification of the pattern late in the period (Fri-Sun), that cooler than normal weather will be returning to the region. The GFS is much more amplified and colder indicating lows potentially in the low to mid 20s by Sunday morning. Both the 10/00z and 10/12z Euro are less intense with the incoming cooler airmass, so weighted the forecast in this direction, which still produces well below normal temperatures by Sunday. && .AVIATION... [Through 12Z Tuesday] This forecast will be an unsettled one with periods of showers and thunderstorms. These will be most frequent across DHN and ABY, but gradually develop southeast to impact the remaining terminals as a cold front approaches from the northwest. MVFR conditions will prevail for the most part, with periods of IFR early this morning and again overnight. South to southwest winds will be gusty today at all of the terminals with gusts to around 20 kt. Gusts is TS will be higher. Finally, incoming data from the KTAE 12Z upper air sounding indicated 40-kt winds at around 1500 ft and this was supported by the KTLH and KEVX WAD wind profile data. We included a LLWS group at TLH and ECP accordingly. && .MARINE... Based on latest buoys, Small craft advisory will be allowed to drop across the western waters with this package Winds will remain below headline criteria despite occasional storms until Wednesday when an area of low pressure will move across the Gulf. Winds will increase to near advisory levels at this time. Winds will shift to offshore on Thursday and then diminish into the weekend. && .FIRE WEATHER... A cold front will settle south across the forecast area from northwest to southeast today into tonight. This front will then return inland as a warm front on Tuesday as a low pressure system tracks from the north central Gulf of Mexico northeast across the southeastern states. This low will finally drag a stronger cold front across the region on Wednesday. Drier air will arrive behind this front for later in the work week. However, temperatures will also be much cooler which will keep relative humidities above critical values. && .HYDROLOGY... Overnight, some of the flashier rivers across SE AL has shown notable rises and need to be monitored in case a river flood product is necessary later today. Expect 2 to 4 inches of rain across the region starting through Wednesday with the heaviest totals across Southern Alabama and Georgia. Isolated higher totals up to 5 inches are possible. Widespread flooding is not anticipated. However, rises on rivers are anticipated with this rainfall, particularly further to the north where the combination of local runoff and routed upstream flows lead to a few locations reaching minor flood stage later this week. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 77 57 66 58 69 / 70 60 60 80 80 Panama City 74 58 65 57 67 / 80 60 60 90 80 Dothan 73 53 62 55 61 /100 80 80 90 80 Albany 73 52 60 54 67 /100 80 80 90 80 Valdosta 78 54 63 55 69 / 70 60 50 80 70 Cross City 78 57 73 56 72 / 20 40 30 70 70 Apalachicola 72 60 66 60 67 / 60 50 50 80 80 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...FLASH FLOOD WATCH through Tuesday morning for Baker-Calhoun- Clay-Dougherty-Early-Lee-Miller-Quitman-Randolph-Terrell. AL...FLASH FLOOD WATCH through late tonight for Coffee-Dale-Geneva- Henry-Houston. GM...None. && $$ MESOSCALE UPDATE...Lamers NEAR TERM...Wool SHORT TERM...Block LONG TERM...Godsey AVIATION...Wool MARINE...Block FIRE WEATHER...Wool HYDROLOGY...Block
AREA FORECAST DISCUSSION...UPDATED
NWS TAMPA BAY RUSKIN FL
350 AM EST MON FEB 11 2013 .SYNOPSIS... 08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A CHAOTIC UPPER LEVEL PATTERN ACROSS THE MID-SECTION OF THE COUNTRY CONSISTING OF 2 CLOSED UPPER LOW FEATURES. THE FIRST IS EJECTING EASTWARD ACROSS THE UPPER MIDWEST AND GREAT LAKES WHILE THE SECOND IS FURTHER UPSTREAM NEAR THE 4-CORNERS REGION. IN RESPONSE TO THE HEIGHT FALLS SEEN OVER THE CENTRAL STATES...THE DOWNSTREAM RIDGE AS BEEN AMPLIFIED AND IS NOW QUITE SHARP AS ITS AXIS BEGINS TO EXIT THE EASTERN SEABOARD. THE FL PENINSULA RESIDES AT THE BASE OF THE EAST COAST RIDGE. THE INFLUENCE OF THIS FEATURE ON OUR COLUMN WAS SAMPLED WELL BY THE 11/00Z KTBW SOUNDING WHICH SHOWED A DEFINED SUBSIDENCE INVERSION AROUND 800MB. AT THE SURFACE...STRONG HIGH PRESSURE HAS BEEN PUSHED OFF THE ATLANTIC SEABOARD BY A COLD FRONT MOVING THROUGH THE APPALACHIANS...BUT CONTINUES TO RIDGE TO THE SOUTHWEST ACROSS THE LOCAL AREA AND EASTERN GULF. THIS PRESSURE PATTERN IS ALLOWING FOR A LIGHT EAST TO SOUTHEAST FLOW AND A SLOW INCREASE IN LOW LEVEL MOISTURE. REGIONAL RADARS SHOW PLENTY OF SHOWERS AND STORMS TO OUR NORTHWEST TOWARD THE I-10 CORRIDOR. THIS ACTIVITY WILL NOT BE A THREAT TO OUR ZONES AS SUPPORTING ENERGY QUICKLY EXITS LATER TODAY AND THE FRONT NEVER REACHES THIS FAR SOUTH. && .SHORT TERM (TODAY THROUGH WEDNESDAY)... TODAY/TONIGHT... UPPER RIDGE OVER THE EASTERN SEABOARD WILL QUICKLY BREAK DOWN AS A STRONG UPPER LOW QUICKLY TRANSLATES EASTWARD THROUGH THE GREAT LAKES TOWARD THE NORTHEAST/MID-ATLANTIC. LUCKILY FOR OUR FORECAST...SOME RESIDUAL RIDGING WILL HOLD ON DOWN TOWARD THE FLORIDA PENINSULA... AND THIS PATTERN OVER-TOP AN EAST-WEST ORIENTED SURFACE RIDGE WILL KEEP OUR LOCAL WEATHER GENERALLY FAIR...DRY...AND WARM. AS MENTIONED ABOVE...ANY SHOWER ACTIVITY SHOULD STAY TO OUR NORTH TODAY AND WILL KEEP MENTION OUT OF THE FORECAST. EFFICIENT DIURNAL MIXING AND A LOW LEVEL COLUMN FEATURING 850MB TEMPS BETWEEN 12-14C WILL ALLOW FOR A QUICK DIURNAL RISE IN TEMPERATURES INTO THE UPPER 70S AND LOWER 80S. MAY SEE SOME ONSHORE COMPONENT DEVELOP ALONG THE IMMEDIATE COAST DURING THE AFTERNOON WHICH WILL KEEP TEMPS DOWN A FEW DEGREES FROM LOCATIONS FURTHER INLAND...BUT EVEN STILL A DECENT BEACH DAY IS IN STORE. LOW TEMPERATURES TONIGHT WILL BOTTOM OUT ONLY IN THE UPPER 50S TO LOWER 60S FOR MOST SPOTS AND IN THE MIDDLE 60S ALONG THE COAST FROM TAMPA BAY SOUTHWARD. THE INCREASING LOW LEVEL DEWPOINTS WILL BEGIN TO APPROACH A CRITICAL POINT LATER TONIGHT OVER THE COOLER SHELF WATERS...AND CONCERNED FOR THE POTENTIAL DEVELOPING OF SOME ADVECTION SEA-FOG. MANY OF THE HIGHER RESOLUTION GUIDANCE MEMBERS ARE AGGRESSIVE IN THIS SEA-FOG DEVELOPMENT FROM THE MANATEE COUNTY COAST AND NORTHWARD...AND ADDED AREAS OF FOG TO THE GRIDS. TUESDAY/TUESDAY NIGHT... NEXT SHORTWAVE WILL BEGIN TO MOVE EASTWARD FROM THE SOUTHERN PLAINS AND SUPPORT AND ORGANIZING AREA OF LOW PRESSURE NEAR THE LA/MS/AL COAST BY LATE IN THE DAY. A WARM FRONTAL FEATURE WILL EXTEND EASTWARD FROM THIS LOW ALONG THE I-10 CORRIDOR. THIS CONFIGURATION WILL PLACE OUR REGION WITHIN THE WARM SECTOR AND REMOVED FROM ANY DECENT UPGLIDE OVER THE FRONT. WITH THIS IN MIND...MAY SEE A FEW SCATTERED SHOWERS AS FAR SOUTH AS LEVY COUNTY...BUT ANY ORGANIZED CONVECTION WILL BE FURTHER NORTH INTO AL/GA. THE REMAINDER OF THE AREA...WILL BE GENERALLY DRY (OUTSIDE OF AN ISOLATED INSTABILITY SHOWER). IF THE SEA-FOG POTENTIAL DOES COME TO VERIFY...THEN WE WOULD STILL BE DEALING WITH THESE VISIBILITY ISSUES DURING THE MORNING HOURS...WITH DIURNAL MIXING SHRINKING THE MAIN VIS RESTRICTION REGION BACK TO THE MARINE ZONES AND IMMEDIATE NATURE COAST FOR THE SECOND HALF OF THE DAY. THE AREA OF LOW PRESSURE WILL MOVE NORTHEAST ACROSS AL TUESDAY NIGHT WITH A TRAILING COLD FRONT APPROACHING FROM THE WEST. TIMING OF THE FRONT AND SWATH OF LARGE SCALE LIFT/QG FORCING LOOKS TO KEEP THE BEST SHOWER/STORM POTENTIAL HELD OFF FOR THE PENINSULA UNTIL THE DAYLIGHT HOURS OF WEDNESDAY. MAY VERY WELL BE DEALING WITH SEA-FOG EXPANDING ONCE AGAIN AFTER SUNSET TUESDAY EVENING. WEDNESDAY...STRONG SHORTWAVE PASSES TO OUR NORTH PUSHING A COLD FRONT THROUGH THE AREA. THE SHORTWAVE PATH PROVIDES THE BEST SETUP FOR LARGE SCALE LIFT OVER THE NORTHERN HALF OF THE AREA...WHICH IS FAIRLY TYPICAL. HIGHEST RAIN CHANCES WILL EXIST FROM TAMPA BAY NORTHWARD ACROSS THE NATURE COAST. A MORE BROKEN BAND OF SHOWERS AND DECREASING RAIN CHANCES WILL EXIST FURTHER SOUTH LATE IN THE DAY WHEN THE BEST KINEMATICS WILL BE SHIFTING AWAY AS THE LOW LEVEL FRONTAL FOCUS ARRIVES. && .LONG TERM (WEDNESDAY NIGHT THROUGH NEXT SUNDAY)... MUCH OF THE EXTENDED FORECAST WILL BE PLAGUED BY RAIN CHANCES AS A SERIES OF UPPER-LEVEL IMPULSES MAINTAIN A TROUGH OVER THE EASTERN HALF OF THE NATION. GLOBAL MODELS ARE ACTUALLY IN QUITE GOOD AGREEMENT CONSIDERING THE COMPLEXITY AND EVENTUAL EVOLUTION OF THE UPPER-LEVEL PATTERN. THE TRICK WILL BE IN NAILING DOWN WHEN OUR BEST RAIN CHANCES WILL BE. LOW PRESSURE WILL BE PULLING AWAY FROM THE MID-ATLANTIC COAST WEDNESDAY NIGHT. A TRAILING COLD FRONT WILL BE WORKING ITS WAY SOUTHWARD ACROSS FLORIDA. THE ECMWF KEEPS AMPLE MOISTURE AND ENOUGH LIFT BEHIND THE FRONT TO CONTINUE RAIN CHANCES OVERNIGHT. THE GFS AND CANADIAN DRY US OUT A LITTLE...BUT ALSO SHOW A CHANCE OF SHOWERS THROUGH AT LEAST THE FIRST HALF OF THE NIGHT. WILL CONTINUE LOW-END CHANCE POPS FOR NOW. ON THURSDAY...WEST TO SOUTHWEST FLOW OVER THE TOP OF OUR SHALLOW COOL AIRMASS WILL LEAD TO PLENTY OF CLOUDS AND MOST LIKELY SOME SHOWERS HERE AND THERE. USING A BLEND OF GUIDANCE YIELDS CHANCE POPS ONCE AGAIN...WHICH IS HIGHER THAN THE DRIER GFS/MEX. FRIDAY AND SATURDAY WILL BE TOUCH CALLS AS FAR AS RAIN POTENTIAL GOES. CERTAINLY FRIDAY HAS A GOOD CHANCE OF BEING WET SO INCLUDED 40 TO 50 PERCENT RAIN CHANCES FOR MOST OF THE AREA. SATURDAYS WEATHER WILL DEPEND ON THE TIMING AND DEPTH OF A RATHER IMPRESSIVE UPPER-LEVEL TROUGH FORECAST TO DIG SOUTHWARD INTO THE GULF. THE GFS IS WEAKER AND LESS AMPLIFIED WHICH RESULTS IN A SLOWER MOVING COLD FRONT THAT TAKES ITS TIME CLEARING OUT THE MOISTURE. THE ECMWF AND CANADIAN ARE DEEPER AND STRONGER...WITH THE FRONT CLEARING THE FLORIDA PENINSULA DURING THE DAY SATURDAY. ALL THREE OF THESE MODELS SHOW MUCH COLDER AIR POISED TO INVADE OUR REGION FROM THE NORTH. I AM INITIALLY LEAVING SOME RAIN CHANCES IN FOR SATURDAY FOR ALL BUT THE FAR NORTH...BUT IF THE GFS COMES ON BOARD WITH THE ECMWF...WE MAY BE ABLE TO SALVAGE A GOOD PART OF THE DAY. BY SUNDAY...ALL THE MODELS HAVE THE FRONT THROUGH THE AREA WITH COLD HIGH PRESSURE SETTLING IN OVER THE NORTHERN GULF. EVEN UNDER BRIGHT SUNSHINE ON SUNDAY...WE WOULD LIKELY STRUGGLE TO GET OUT OF THE 60S. THE 00Z ECMWF ACTUALLY SUPPORTS TEMPERATURES HOLDING IN THE 50S ALL DAY. I HAVE BASICALLY USED THE WARMER MEX NUMBERS FOR NOW...BUT I HAVE A FEELING WE WILL NEED TO TREND COLDER WITH TIME. IT IS WORTH NOTING THAT THERE IS THE POTENTIAL FOR FREEZING TEMPERATURES FOR MUCH OF THE INTERIOR AND NORTHERN ZONES SUNDAY NIGHT. WE WILL LOOK MORE AT THIS AS WE MOVE CLOSER TO THE EVENT. && .AVIATION... EXPECTING MAINLY VFR CONDITIONS THROUGH TODAY AND INTO THIS EVENING. SOME PATCHY FOG COULD BRING MVFR VISIBILITIES TO PGD AND LAL THIS MORNING. A MORE SIGNIFICANT FOG EVENT IS POSSIBLE AFTER 06Z TONIGHT WITH THE MOST FAVORED LOCATIONS BEING FROM SRQ NORTHWARD TO TPA AND PIE. && .MARINE... HIGH PRESSURE WILL CONTINUE TO RIDGE ACROSS THE FL PENINSULA AND EASTERN GULF WATERS THROUGH THIS AFTERNOON AND THEN RETREAT EASTWARD TONIGHT INTO TUESDAY IN RESPONSE TO THE DEVELOPMENT OF A WARM FRONTAL FEATURE AND SURFACE LOW ALONG THE NORTHERN GULF COAST. THIS LOW WILL DRIFT TO OUR NORTH DURING THE MIDWEEK PERIOD WITH A TRAILING COLD FRONT SHIFTING ACROSS THE EASTERN GULF WEDNESDAY AFTERNOON AND NIGHT. SOUTHEAST WINDS WILL APPROACH CAUTIONARY LEVELS AWAY FROM SHORE THIS MORNING AND THEN DIMINISH BELOW HEADLINE CRITERIA THIS AFTERNOON AND EVENING. WINDS WILL THEN ONCE AGAIN INCREASE TO CAUTIONARY LEVELS TUESDAY NIGHT AND WEDNESDAY AHEAD OF THE APPROACHING COLD FRONT. WINDS WILL SHIFT NORTH AND THEN QUICKLY NORTHEAST ON THURSDAY IN THE WAKE OF THIS FRONT. && .FIRE WEATHER... NO FIRE WEATHER CONCERNS ARE EXPECTED THE NEXT SEVERAL DAYS AS SOUTHEAST TO SOUTHERLY FLOW BRING A SLOW INCREASE IN LOW LEVEL MOISTURE AND PREVENT CRITICAL LEVELS OF RELATIVE HUMIDITY. THE INCREASE IN LOW LEVEL MOISTURE IS EXPECTED TO INCREASE THE POTENTIAL FOR SEA FOG TO IMPACT LOCATIONS NEAR THE COAST...ESPECIALLY MANATEE COUNTY NORTHWARD THROUGH THE NATURE COAST. THIS POTENTIAL FOR LOCALLY DENSE FOG WILL BEGIN LATE TONIGHT. && .PRELIMINARY POINT TEMPS/POPS... TPA 79 64 79 67 / 10 10 10 20 FMY 84 62 83 66 / 10 10 10 10 GIF 82 62 82 63 / 10 10 10 20 SRQ 79 60 79 67 / 10 10 10 10 BKV 81 57 80 64 / 10 10 10 40 SPG 80 64 79 67 / 10 10 10 20 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...BEACH HAZARDS STATEMENT UNTIL 2 PM EST THIS AFTERNOON FOR CHARLOTTE-LEE. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WEATHER...MROCZKA LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1000 PM EST TUE FEB 12 2013 .SYNOPSIS... A STATIONARY FRONT OVER FAR SOUTH GEORGIA WILL LIFT NORTH INTO THE AREA AS A WARM FRONT LATE TONIGHT...WHILE GULF LOW PRESSURE PASSES TO THE WEST. A COLD FRONT WILL SWEEP THROUGH THE AREA LATE WEDNESDAY... WITH HIGH PRESSURE EXPECTED TO BUILD ACROSS THE REGION THURSDAY INTO EARLY SATURDAY. ANOTHER COLD FRONT WILL PUSH THROUGH THE AREA SATURDAY...FOLLOWED BY STRONGER HIGH PRESSURE AND COOLER CONDITIONS INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... MID EVENING SURFACE ANALYSIS IS COMPLEX AS THE GULF COAST WARM FRONT INTO FAR SOUTH GEORGIA SLOW TO MAKE A MOVE N AS YET. WIDESPREAD RAINS WERE FALLING UNDER COOLER IR SATELLITE TOPS OVER MUCH OF GEORGIA AND SOUTH CAROLINA. A MESOSCALE LOW PRES AREA WAS LOCATED NEAR A BATCH OF ELEVATED CONVECTION IN SOUTH GEORGIA. WEAK PRES FALLS WERE ONGOING E OF THIS LOW INTO SE GEORGIA AT 02Z. MODELS DOING A REASONABLE JOB WITH RAIN DEPICTION BUT MAY STRUGGLE OVERNIGHT WITH THE DETAIL OF THE WARM FRONTAL PROGRESSION GIVEN COMPLICATED SURFACE LAYERED STABILITY PROFILES. TEMPS WERE IN THE MID 50S MOST AREAS AS NEAR SATURATION EVIDENT ON SOUNDING PROFILES. OVERNIGHT...A FAIRLY UNSTABLE MID LEVEL ENVIRONMENT WILL SPREAD OVER THE FORECAST REGION BUT GIVEN THE CURRENT RADAR TRENDS AND A MORE BELIEVABLE RUC FORECAST...THE POTENTIAL FOR SEVERE WEATHER OVERNIGHT DOES NOT APPEAR TOO IMPRESSIVE DESPITE INCREASING SHEAR PROFILES. 01Z RUC SUGGESTS CONVECTION INCREASING OVER SE GEORGIA NEAR THE WARM FRONT WHICH IS STILL ALONG I-16 AT 12Z. NOT TOO MANY FORECAST CHANGES THIS EVENING WITH CATEGORICAL POPS OVERNIGHT AND ONLY SLOWLY WARMING TEMPS WHERE RAINS WERE STEADIER AND HEAVIER. THE BEST CHANCE FOR TEMPS RISING INTO THE MID 60S OR WARMER LATE SHOULD BE TO THE S OF I-16. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... WEDNESDAY...A STRONG SHORTWAVE TROUGH CURRENTLY OVER THE SOUTHERN PLAINS WILL STEADILY SHIFT EAST EARLY WEDNESDAY...BECOMING MORE STRETCHED/SHEARED AS IT MOVES INTO THE TENNESSEE/LOWER MISSISSIPPI VALLEYS BY MIDDAY. THIS UPPER LEVEL ENERGY WILL SUPPORT THE DEVELOPMENT OF A SURFACE LOW LIFTING FROM THE GULF COAST STATES INTO THE UPSTATE CAROLINAS AS THE DAY PROGRESSES. NUMERICAL MODELS ARE IN DECENT AGREEMENT THAT THE ASSOCIATED WARM FRONT WILL BE LOCATED RIGHT ALONG THE NORTHERN BORDER OF THE FORECAST AREA...PERHAPS AROUND THE SANTEE RIVER...BY DAYBREAK WEDNESDAY. AS A RESULT...TEMPERATURES WILL RISE WELL ABOVE SEASONAL NORMALS INTO THE UPPER 60S NORTH TO LOWER 70S SOUTH. BOTH 12Z NAM AND 12Z GFS SOLUTIONS INDICATE LOW TO MODERATE INSTABILITY INCREASING ACROSS MUCH OF THE FORECAST AREA THROUGH THE MORNING AND AFTERNOON HOURS...WITH CAPE VALUES POSSIBLY REACHING 1000 J/KG OVER THE CHARLESTON TRI COUNTY REGION BY 18Z. THE SOUTHEAST STATES WILL BE IN THE VICINITY OF THE RIGHT REAR OF A 100 KT 500 MB JET AND A 30 TO 40 KT LOW LEVEL JET. THE COMBINATION OF MODERATELY FAVORABLE INSTABILITY AND DECENT SHEAR SUGGESTS ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE...WITH A FEW THUNDERSTORMS POTENTIALLY BECOMING STRONG AND ORGANIZED. STORM PREDICTION CENTER HAS PLACED THE SOUTHERN HALF OF THE FORECAST AREA...WHERE TEMPERATURES AND DEWPOINTS WILL BE HIGHEST...WITHIN A SLIGHT RISK FOR SEVERE THUNDERSTORM DEVELOPMENT. WILL ADD MENTION OF ISOLATED STORMS POSSIBLY BECOMING SEVERE IN THE HAZARDOUS WEATHER OUTLOOK. IT SHOULD BE NOTED THAT THICK CLOUD COVER AND MARGINAL LAPSE RATES COULD NEGATIVELY IMPACT STORM ORGANIZATION...AND MUCH UNCERTAINTY IN THUNDERSTORM STRENGTH AND COVERAGE REMAINS. WEDNESDAY NIGHT...AS THE SURFACE LOW CONTINUES TO LIFT NORTH/NORTHEAST TOWARD THE MID ATLANTIC COASTLINE...A TRAILING COLD FRONT WILL PULL THROUGH THE FORECAST AREA BY THE EVENING HOURS. SHOWER AND THUNDERSTORM CHANCES WILL THUS END FAIRLY QUICKLY FROM WEST TO EAST BETWEEN 00Z AND 06Z WEDNESDAY NIGHT...WITH DRIER DEEP LAYER AIR MOVING IN BEHIND THE DEPARTING FRONT. COLD ADVECTION OVERNIGHT WILL ALLOW TEMPERATURES TO FALL INTO THE UPPER 30S INLAND TO THE LOWER 40S NEAR THE COAST. THURSDAY AND FRIDAY...WEAK SURFACE HIGH PRESSURE WILL BUILD INTO THE REGION AND SET UP PREVAILING WEST/NORTHWEST SYNOPTIC FLOW. EXPECT DRY CONDITIONS AND SLIGHTLY COOLER TEMPERATURES...WITH HIGHS GENERALLY REACHING THE MID 60S THURSDAY AND THE MID TO UPPER 60S FRIDAY. LOW TEMPERATURES THURSDAY NIGHT WILL REFLECT IMPROVED RADIATIONAL COOLING CONDITIONS UNDER CLEAR SKIES AND LIGHTER WINDS...RANGING FROM THE MID TO UPPER 30S INLAND TO THE LOWER 40S NEAR THE COAST. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AN ARCTIC FRONT WILL PUSH THROUGH THE SOUTHEAST STATES LATE SATURDAY AHEAD OF A SHARP UPPER TROUGH DIVING TOWARD THE AREA FROM THE GREAT LAKES/CENTRAL PLAINS REGION. THERE IS SOME EVIDENCE IN MEDIUM RANGE MODEL SOLUTIONS OF ISOLATED RAIN ASSOCIATED WITH THE UPPER TROUGH PROGRESSION TO SUPPORT SLIGHT CHANCE POPS FOR THE NORTHERN HALF OF THE AREA SATURDAY NIGHT. GUIDANCE IS STILL SHOWING HIGHS IN THE UPPER 50S TO LOWER 60S AHEAD OF THE FRONT ON SATURDAY...BUT SUSPECT TEMPERATURES WILL BE FALLING DURING THE AFTERNOON DEPENDING ON THE EXACT TIMING OF THE FRONT. THERE IS SOME CONCERN ABOUT THE POTENTIAL FOR SOME BRIEF WINTRY PRECIP WITH THIS FRONT...AS MODELS DROP 850MB TEMPS TO -2 TO -4C BY 00Z SUNDAY. HOWEVER...BOUNDARY LATER TEMPS COULD BE TOO WARM. PREFER TO CONTINUE MONITORING MODEL TRENDS FOR THIS PERIOD. THE DEEP ARCTIC UPPER TROUGH PUSHES OFFSHORE INTO THE ATLANTIC SUNDAY...THEN ZONAL FLOW TO SLIGHT RIDGING BUILDS BACK INTO THE UPPER LEVELS FOR MONDAY. BELOW CLIMO TEMPS EXPECTED FOR SUNDAY AND MONDAY WITH HIGHS IN THE 50S...AS WELL AS THE POTENTIAL FOR FREEZING OVERNIGHT/EARLY MORNING TEMPS...ESPECIALLY MONDAY MORNING. EXPECT MODERATING TEMPS BY TUESDAY AS MODELS SHOW ANOTHER STRONG UPPER TROUGH AND ASSOCIATED SURFACE FRONT MOVING TOWARD THE REGION. DUE TO UNCERTAINTY IN THE TIMING OF THIS FEATURE...HAVE GONE WITH SLIGHT CHANCE TO CHANCE POPS. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... OVERNIGHT...MODELS SUGGEST HIGHEST CERTAINTIES OF PROLONGED RAINS AT KCHS WITH PERIODS OF RAIN AT KSAV OVERNIGHT AT KSAV. KSAV SHOULD MAINTAIN A BLANKET OF STRATUS/STRATOFRACTUS OVERNIGHT THUS A CONTINUATION OF IFR/LIFR CIGS. AT KCHS WHERE THE RAIN GOT OFF TO A LATER START...WE THINK CONDITIONS WILL DETERIORATE TO IFR OR LOWER DURING THE EVENING AND PERSIST OVERNIGHT. WE HAVE INTRODUCED LLWS AT BOTH AIRPORTS AS A STRONG AND VEERING 40-50 KT LOW LEVEL JET DEVELOPS THROUGH THE COASTAL CORRIDOR. ON THU...BOTH TERMINALS WILL SEE WINDS BECOMING SW AND EVENTUALLY W LATE AS A FRONT MOVES TO THE COAST. IFR OR LOWER CONDITIONS SHOULD BECOME MVFR AND PROBABLY VFR BY LATE AFTERNOON AS OFFSHORE FLOW COMMENCES. TIMING OF CONVECTIVE RAINS GETS QUITE TRICKY AS MODEL DISCREPANCIES CAN INTO THE PICTURE. IT APPEARS LIKELIHOODS FOR RAIN QUICKLY BEGIN TO DIMINISH AFTER MID AFTERNOON. EXTENDED AVIATION OUTLOOK...MAINLY VFR THROUGH THE WEEKEND. && .MARINE... RELATIVELY WEAK WINDS/SEAS THIS EVENING WILL GIVE WAY TO SOUTHERLY FLOW OVERNIGHT FROM SOUTH TO NORTH AS A WARM FRONT LIFTS NORTH AND A LOW-LEVEL JET DEVELOPS. SOME GUSTS TO 25 KT WILL BECOME POSSIBLE AFTER MIDNIGHT ACROSS THE OFFSHORE GA WATERS. ELSEWHERE IT WILL BE CLOSER TO DAYBREAK WEDNESDAY WHEN THE WINDS BECOME MORE GUSTY. WE HAVE THE SMALL CRAFT ADVISORY FOR OFFSHORE GA WATERS TONIGHT. WEDNESDAY THROUGH SUNDAY...SMALL CRAFT ADVISORY CONDITIONS WILL BE ONGOING FOR MUCH OF THE MARINE AREA WEDNESDAY...AS A SURFACE LOW PASSES WELL NORTHWEST OF THE WATERS AND A COLD FRONT CROSSES OFFSHORE DURING THE EVENING HOURS. EXPECT WINDS AND SEAS TO GRADUALLY FALL BELOW ADVISORY LEVELS LATE WEDNESDAY NIGHT INTO THURSDAY MORNING...WITH HIGH PRESSURE BUILDING OVER THE REGION FROM THE WEST. A STRONGER COLD FRONT AND HIGH PRESSURE IS EXPECTED TO SUPPORT ANOTHER SURGE IN WINDS TO ADVISORY LEVELS LATER SATURDAY AND SATURDAY NIGHT. THERE IS EVEN THE POTENTIAL FOR SOME MARGINAL GALE CONDITIONS SATURDAY NIGHT...HOWEVER UNCERTAINTY IS TOO HIGH TO MENTION AT THIS POINT. WINDS AND SEAS WILL BE GRADUALLY FALLING BACK BELOW HIGHLIGHTS SUNDAY...AS HIGH PRESSURE BUILDS OVER THE REGION AGAIN. && .HYDROLOGY... PERIODS OF DROUGHT-RELIEVING RAINS TO CONTINUE THROUGH WEDNESDAY. STORM TOTAL RAINFALL AMOUNTS OF 2-4 INCHES WILL BE SPREAD OVER A LONG ENOUGH PERIOD TO PRECLUDE WIDESPREAD FLASH FLOOD ISSUES... BUT SEVERAL OF OUR RIVERS ARE EXPECTED TO APPROACH FLOOD STAGE LATER IN THE WEEK. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 10 PM EST WEDNESDAY FOR AMZ352. SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR AMZ374. SMALL CRAFT ADVISORY FROM 6 AM WEDNESDAY TO 5 AM EST THURSDAY FOR AMZ350. && $$ SYNOPSIS... NEAR TERM... SHORT TERM...79 LONG TERM...RFM AVIATION... MARINE...JRL/RFM HYDROLOGY...
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
635 PM EST TUE FEB 12 2013 .AVIATION... MVFR CIGS WILL POSE A SMALL PROBLEM THIS EVENING WITH RESPECT TO MIXING AND EROSION. HIRES MODEL GUIDANCE VARIES WITH LOW LEVEL MOISTURE WHICH REMAINS TRAPPED UNDER STRONG SUBSIDENCE INVERSION. HAVE SEEN INDICATIONS OF BREAKS IN LAST FEW HOURS AND SFC OBS SHOWING SOME EROSION WITH SOUTHERN FLANK SOUTH OF TAF SITES. WILL REMAIN OPTIMISTIC FOR A FEW MORE HOURS IN GRADUALLY CLEARING THE CIGS BUT THIS MAY NEED TO BE DELAYED FURTHER IF TREND CHANGES WITH LOSS OF SUN AND MIXING. SHOULD SEE THE CLOUDS EVENTUALLY ADVECT OUT AS NEXT WEAK SHORT WAVE APPROACHES ON WEDNESDAY. WINDS WILL BECOME LIGHT AND VARIABLE OVERNIGHT AND REMAIN AT OR UNDER 10 KNOTS ON WEDNESDAY. && .SHORT TERM... SFC RIDGING INVOF OF OH RVR WILL BREAK DOWN INADV OF SW CLIPPER DROPPING OUT OF SWRN CANADA WED AFTN. HWVR NO SENSIBLE WX OF CONSEQUENCE XPCD WITHIN THIS EVOLUTION THROUGH THIS PD. MIXING/EROSION OF SC CLD DECK ONGOING THIS AFTN W/PARTIAL SUNSHINE NOW ACRS MUCH OF ERN HALF CWA BUT WRN FLANK EXTENDING BACK INTO NE IL HOLDING TOUGH AND MAY POSE A BUST OVERNIGHT WRT MIN TEMPS. ATTM SHRT TERM RUC GIVES A NOD TWD PRIOR EVEN MOS BLEND. OTRWS AT LEAST PARTIAL INSOLATION XPCD AGAIN ON WED W/STGR DIURNAL WITHIN MODEST LL SWRLY FLW. IN FACT MOS MAX TEMP SPLIT ESSENTIALLY EVEN AND REFLECTED IN GRIDDED MAXS. && .LONG TERM... /THURSDAY THROUGH TUESDAY/ ACTIVE PATTERN IN STORE FOR THE LONG TERM PERIOD. ONE MORE DAY OF ABOVE NORMAL TEMPS ON TAP FOR THURSDAY AHEAD OF SHOT OF ARCTIC AIR DROPPING SE ACROSS THE PLAINS. STRONG FORCING ALONG THE FRONT WILL STIR UP AT LEAST A CHC FOR RAIN OR SNOW SHOWERS BUT OVERALL QPF APPEARS MINIMAL AT THIS POINT. POPS STILL HELD IN CHC/SCHC RANGE FOR NOW. GREATER FOCUS THEN TURNS TOWARDS LAKE EFFECT POTENTIAL AS STG NW FLOW SETS UP WITH SFC-850 MB DELTA T`S PUSHING 20 C AND SFC-700 MB DELTA T`S PUSHING UPR 20S. NAM/WRF SHOW A PERIOD OF FAVORABLE COLLOCATION OF DGZ AND TOP OF STRONG OMEGA. INVERSION HGTS BEGIN TO CLIMB...ESPECIALLY DURING THE DAY FRIDAY WHEN SOME ADDITIONAL SYNOPTIC MSTR ARRIVES AND A REINFORCING SHOT OF COLD AIR. HAVE TENDED TO FOCUS GREATEST POPS FRIDAY TO MATCH WITH THE ABOVE SETUP. ACCUMS AT THIS POINT APPEAR TO BE ON THE LIGHTER SIDE BUT WILL NEED TO BE WATCHED IN COMING FORECASTS. WHILE AN OUTLIER...SEVERAL RUNS OF THE GEM NHEM MODEL HAVE BEEN SHOWING PHASING OF N/S STREAM SYSTEMS SOONER THAN LATER WITH A STORM AFFECTING THE GREAT LAKES VS EAST COAST. ECMWF/GFS DO NOT PHASES THE ENERGY UNTIL REACHING EAST COAST SO AT THIS POINT HAVE TO PUT IT ON THE BACK BURNER BUT WILL NEED TO WATCH. LAKE EFFECT WILL LINGER POTENTIALLY THROUGH MUCH OF THE WEEKEND WITH CONTINUED NW FLOW AND 850 MB RIDGING STILL TO THE WEST UNTIL LATE SUNDAY. NEXT SYSTEM TO FOCUS ON WILL BE WHAT LOOKS LIKE A PANHANDLE HOOK COMING TOWARDS THE REGION MONDAY NIGHT INTO TUESDAY. SIGNALS POINT TOWARDS MEASURABLE PRECIP FOR PARTS OF THE AREA BUT EXACT TRACK AND AMOUNT OF COLD AIR REMAIN QUESTIONABLE THIS FAR OUT IN THE FORECAST. HAVE WENT WITH MID-HIGH END CHC POPS WITH MIX OF RAIN OR SNOW WITH LIKELY REFINEMENT OF FORECAST TO COME OVER THE NEXT SEVERAL DAYS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...T LONG TERM...FISHER AVIATION...LASHLEY
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1131 PM EST SUN FEB 10 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 215 PM EST SUN FEB 10 2013 A STRONG OCCLUDED SYSTEM WILL LIFT NORTHEAST ACROSS CENTRAL INDIANA LATE TONIGHT WITH THE RAIN EXPECTED TO END IN ITS WAKE. THEN...HIGH PRESSURE WILL BUILD IN FROM THE PLAINS AND SOUTHERN STATES THROUGH TUESDAY ALLOWING FOR DRY WEATHER AND TEMPERATURES CLOSER TO SEASONABLE. A SOUTHERN SYSTEM WILL BRING A CHANCE OF RAIN OR SNOW TO FAR SOUTH CENTRAL INDIANA TUESDAY NIGHT AND WEDNESDAY. THE NEXT CHANCE OF PRECIPITATION AFTER THAT WILL BE THURSDAY NIGHT THROUGH SATURDAY WITH RAIN OR SNOW POSSIBLE AS A LOW PRESSURE SYSTEM PIVOTS ACROSS THE LOWER GREAT LAKES. ABOVE NORMAL TEMPERATURES ON THURSDAY AHEAD OF THE SYSTEM WILL GIVE WAY TO BELOW NORMAL TEMPERATURES LATE IN THE WEEKEND BEHIND AN ASSOCIATED COLD FRONT. && .NEAR TERM /REST OF TONIGHT/... ISSUED AT 719 PM EST SUN FEB 10 2013 LOWERED POPS TO LOW CHANCE/SLIGHT CHANCE ACROSS THE AREA BASED ON RADAR MOSAIC AND HRRR FIELDS FOR THE NEXT SEVERAL HOURS. SOUNDINGS ARE LOOKING MORE LIKE SPRINKLES/DRIZZLE POSSIBLE FOR THE NEXT FEW HOURS AND THEN DRY WITH CLEARING SKIES AS A DRY SLOT CURRENTLY OVER MISSOURI/WESTERN ILLINOIS MOVES THROUGH THE AREA. WIND GUSTS COULD INCREASE A BIT WITH THE ARRIVAL OF THE DRY SLOT AND COULD MAX OUT AROUND 40 MPH. GOING LOWS IN THE MIDDLE 30S TO AROUND 40 SEEM A LITTLE COOL BUT STILL COULD SEE A GOOD DROP WITH CLOUDS BREAKING FROM THE DRY SLOT SO WILL LEAVE ALONE FOR NOW. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... ISSUED AT 215 PM EST SUN FEB 10 2013 MAIN CHALLENGE TO THE FORECAST WILL BE WINDS AND CLOUD COVER MONDAY ALONG WITH RESULTANT TEMPERATURES. ANOTHER MAIN ISSUE IS WHETHER TO BRING ANY POPS IN TUESDAY NIGHT AND WEDNESDAY AND IF SO HOW FAR NORTH TO BRING THEM AS AS MODELS ARE ALL OVER THE PLACE ON A WEAK SOUTHERN SURFACE SYSTEM WITH THE 12Z NAM BRINGING THIS SYSTEM AS FAR NORTH AS NORTHERN KENTUCKY BY 00Z THURSDAY WITH QPF ACROSS ALL OF THE FORECAST AREA WEDNESDAY. AND AT THE OTHER SPECTRUM THE GEM...ECMWF AND GFS HAVE IT WELL SOUTH NEAR THE GULF WITH QPF ONLY ACROSS OUR FAR SOUTH MAINLY WEDNESDAY. THE NAM IS AN OUTLIER WITH A SLOWER AND MUCH STRONGER UPPER SYSTEM AS IT CLOSES INTO AN UPPER LOW AND MOVES INTO SOUTHWESTERN INDIANA BY 00Z THURSDAY WHICH IS THE MAIN REASON FOR ITS FURTHER NORTH SURFACE LOW TRACK AND RESULT QPF. PER HPC HEMISPHERIC DISCUSSION THE NAM SOLUTION REGARDING A STRONGER LOW IS PLAUSIBLE BUT WITH ALL THE OTHER MODELS KEEPING THE SURFACE LOW WELL SOUTH...FAVOR THAT SOLUTION AND ALSO FAVOR A SLOWER SOLUTION PER MODEL TRENDS THAT WOULD FAVOR HOLDING OFF ON POPS UNTIL AFTER 06Z WEDNESDAY SOUTH CENTRAL AND CONTINUING THROUGH THE DAY WEDNESDAY. SMALL POPS ALSO LOOK LIKE THE WAY TO GO FOR NOW ESPECIALLY WITH THE UNCERTAINTY OF TIMING AND STRENGTH OF THE SYSTEM. GETTING BACK TO MONDAY...PLENTY OF LOW LEVEL MOISTURE IS PROGGED TO LINGER AS THE OCCLUDED LOW CENTER MOVES EAST ACROSS SOUTHERN ONTARIO. IN ADDITION...STRONG COLD AIR ADVECTION WILL BE TAKING PLACE. THUS...THINK THERE WILL BE A GOOD DEGREE OF CLOUD COVER AROUND AND FAVOR ADDING MORE CLOUD COVER THAN ALLBLEND AND KEEPING TEMPERATURES AT OR BELOW SIMILAR MOS. BUFKIT SUGGESTS WINDS TO 30 KNOTS AND GUSTS TO OVER 35 KNOTS POSSIBLE. SO...IT IS LOOKING LIKE NEAR ADVISORY CRITERIA. WILL COORDINATE AND MAKE LAST MINUTE DECISION ON WHETHER TO ISSUE AN ADVISORY OR A SPECIAL WEATHER STATEMENT. MONDAY NIGHT...SURFACE HIGH PRESSURE WILL BUILD IN FROM THE PLAINS AND SOUTHERN STATES...BUT MODEL TIME SECTIONS AND SOUNDINGS STILL HOLD ON TO A DECENT AMOUNT OF LOW LEVEL MOISTURE. SO...NOT EXPECTING FULL CLEARING...BUT SHOULD SEE SOME BREAKS. MOS TEMPERATURES VERY CLOSE...SO WILL STICK CLOSE TO THEM. FINALLY...TUESDAY...THE LOW LEVELS DRY UP WITH ONLY SOME HIGH CLOUDS AHEAD OF THE AFOREMENTIONED UPPER SYSTEM EXPECTED. WILL LEAN TOWARDS THE SLIGHTLY WARMER 12Z GFS MOS DUE TO THE LACK OF LOW CLOUDS. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... ISSUED AT 244 PM EST SUN FEB 10 2013 THERE IS SIGNIFICANT VARIABILITY IN EXTENDED PERIOD AS SEVERAL LITTLE DISTURBANCES ROTATE AROUND A VERY BROAD UPPER LEVEL LOW. SO...WILL NOT DEVIATE MUCH FROM LATEST INITIALIZATION NUMBERS. THERE WILL BE PERIODIC CHANCES FOR PRECIP FROM THURSDAY NIGHT THROUGH SUNDAY...BUT PRECIP WILL FLUCTUATE BETWEEN RAIN/WINTRY MIX/SNOW UNTIL COLDER AIR SETTLES IN NEXT WEEKEND. WILL STICK WITH ALLBLEND IN REGARD TO TEMPS AND NOT DEVIATE. && .AVIATION /DISCUSSION FOR 110600Z TAF ISSUANCE/... ISSUED AT 1131 PM EST SUN FEB 10 2013 MVFR CEILINGS WILL IMPACT PRIMARILY KIND AND KBMG FOR THE FIRST COUPLE HOURS OF THE FORECAST...FOLLOWED BY VFR CONDITIONS. MVFR CEILINGS MAY REDEVELOP BY LATE MORNING AT KLAF. STRONG WIND GUSTS WILL IMPACT ALL TERMINALS THROUGH THE FORECAST PERIOD. CLEARING AREA ASSOCIATED WITH THE DRY SLOT MAKING STEADY EASTWARD PROGRESS AND SHOULD BE EAST OF BOTH KHUF AND KLAF BY 06Z. HAVE HELD ONTO MVFR CEILINGS AT KBMG AND KIND FOR A COUPLE HOURS BUT EXPECT SKIES CLEARING AT THESE SITES AS WELL BY 08Z. MAINLY CLEAR SKIES ARE THEN EXPECTED FOR MUCH OF THE REGION FOR THE REST OF THE OVERNIGHT WITH SOUTHWEST WIND GUSTS STEADILY INCREASING TO NEAR 30KTS BY DAYBREAK. STRATUS ASSOCIATED WITH THE COLD POOL WILL WORK BACK INTO KLAF TOWARDS DAYBREAK...GRADUALLY EXPANDING SOUTHEAST TO ENCOMPASS THE OTHER TERMINALS THROUGH LATE MORNING. MVFR CEILINGS ARE POSSIBLE AT KLAF BUT OTHERWISE EXPECT CLOUD HEIGHTS TO SETTLE BETWEEN 3-4KFT FOR THE AFTERNOON. WINDS WILL BE A SIGNIFICANT FACTOR ON AVIATORS MONDAY AS TIGHT PRESSURE GRADIENT AND STRONG WINDS ALOFT PERSIST AS DEEP LOW PRESSURE MOVES EAST ACROSS THE GREAT LAKES. PREDOMINANT WIND DIRECTION FOR THE AFTERNOON WILL BE 250-260 DEGREES WITH SUSTAINEDS AT 25 TO 30KTS AND GUSTS APPROACHING 40KTS. WINDS WILL BEGIN TO RELAX MONDAY EVENING AS HIGH PRESSURE BUILDS ACROSS THE REGION WITH SKIES SLOWLY CLEARING FROM THE SOUTHWEST. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...MK NEAR TERM...CP SHORT TERM...MK LONG TERM....TDUD AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1146 AM CST MON FEB 11 2013 .SHORT TERM /TODAY/... MAIN FORECAST CONCERN TODAY IS WITH WINDS...AND LIGHT SNOW SHOWERS/FZDZ ACROSS NORTHERN IOWA. VERTICALLY STACKED LOW WILL CONTINUE TO PUSH EASTWARD THROUGH THE DAY AND PRESSURE GRADIENT BEGINS TO RELAX DURING THE AFTERNOON HOURS. NAM/GFS BUFR SOUNDINGS SUGGEST SOME LIGHT SNOW SHOWERS OR FLURRIES OVER NORTHERN IOWA THROUGH 18Z BUT RAP SHOWING LOSS OF ICE INTRODUCTION IN THE COLUMN PERIODICALLY DURING THE MORNING. SEVERAL CURRENT OBSERVATIONS ACROSS NORTHERN IOWA REPORTING DZ/UP SUGGESTING THIS IS ALREADY OCCURRING. FORCING REMAINS WEAK BUT LOOKS TO BE ENOUGH TO WARRANT THE MENTION OF PATCHY FZDZ ACROSS THE NORTHEAST THROUGH 18Z. WENT CLOSE TO GUIDANCE TODAY FOR MAX TEMPERATURES AS MODELS ARE IN GOOD AGREEMENT AND FELT NO REASON TO DEVIATE MUCH FROM THEM. THIS RESULTED IN TWEAKING TEMPS UP SLIGHTLY ACROSS THE SOUTH. NOT EXPECTING STRATUS TO CLEAR OUT ACROSS THE SOUTHWEST UNTIL AFTER 21Z WHEN THE PRESSURE GRADIENT BEGINS TO WEAKEN. KEPT OVERCAST OVER THE NORTH TO EAST THROUGH 00Z TUESDAY AS LOW LEVEL MOISTURE REMAINS PERSISTENT WITHIN THE CAA. .LONG TERM /TONIGHT THROUGH SUNDAY/... THE UPPER LOW PRESSURE WILL CONTINUE TO RACE OFF TO THE EAST TONIGHT AND BE NEAR MAIN BY 12Z TUESDAY MORNING. THIS WILL ALLOW MUCH DRIER AIR TO FILTER INTO THE STATE AS BROAD AREA OF HIGH PRESSURE SHIFTS EAST INTO THE MIDWEST. GENERAL TRENDS FOR TUESDAY AND WEDNESDAY ARE WARMER. THE DRY AIR WILL WARM NICELY ON TUESDAY UNDER SOUTHWEST FLOW. THE FLOW WILL BECOME MORE DOWN SLOPE ORIENTED TUESDAY NIGHT INTO WEDNESDAY AHEAD A VIGOROUS UPPER WAVE THAT WILL ARRIVE ALONG WITH AN ASSOCIATED COLD FRONT WEDNESDAY NIGHT. TEMPERATURES ON WEDNESDAY WILL BE IN THE MID TO UPPER 40S OVER THE CENTRAL AND SOUTH AND A FEW LOCATIONS MAY HIT 50 IF ENOUGH SUN IS AVAILABLE. THE UPPER WAVE WILL PASS THROUGH WEDNESDAY NIGHT INTO THURSDAY. GUSTY NORTHWEST WINDS WILL KEEP COLD ADVECTION IN PLACE THROUGH THE DAY THURSDAY AND MAY HAVE SLOWLY FALLING TEMPERATURES DURING THE AFTERNOON. THE AIR MASS WITH THE SYSTEM WILL BE FAIRLY DRY WITH PWATS GENERALLY ONE QUARTER INCH OR LESS THEREFORE NO PRECIPITATION IS EXPECTED. ANOTHER UPPER WAVE WILL DROP INTO THE REGION THURSDAY NIGHT AND FRIDAY AND WILL HELP CARVE A LONG WAVE TROUGH OUT ACROSS THE NORTHERN PLAINS AND INTO THE EASTERN CONUS. THIS WILL BE ENHANCED AS HUDSON BAY UPPER LOW DROPS SOUTH INTO THE UPPER GREAT LAKES. 850 MB TEMPERATURES OVER THE STATE WILL BE AROUND -16C BY MID DAY FRIDAY. THE COLD AIR MASS WILL BE RELATIVELY DEEP AND WILL BE ABLE TO MIX WELL. THEREFORE DESPITE THE COLD AIR MASS...DEEP MIXING TO NEAR 850 MB WILL ALLOW TEMPERATURES RISE INTO THE UPPER TEENS TO UPPER 20S. SATURDAY AND SUNDAY WILL SEE GRADUAL MODERATION AS A WEAK RIDGE MOVES INTO THE STATE IN RESPONSE TO A STRONG SHORT WAVE DIVING INTO THE INTER MOUNTAIN WEST. && .AVIATION...11/18Z LOW PRESSURE OVER EASTERN LAKE SUPERIOR WILL MOVE INTO ONTARIO THIS AFTERNOON AS WEAK HIGH PRESSURE BUILDS INTO THE AREA. PRESSURE GRADIENT WILL GRADUALLY SLACKEN AS LOW RETREATS. AREAS OF MVFR CIGS WILL LIFT OUT OF THE AREA WITH THE LOW AS WINDS DIMINISH. SOME -SHSN AND BLSN IN THE KMCW AND KALO AREAS WILL ABATE AFTER 21Z. CLEARING TONIGHT WITH WINDS BECOMING LIGHT WEST...THEN SOUTHWEST LATE. && .DMX WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR BLACK HAWK-BREMER-BUTLER-CERRO GORDO- EMMET-FRANKLIN- GRUNDY-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-KOSSUTH-PALO ALTO- POCAHONTAS-TAMA-WEBSTER-WINNEBAGO-WORTH-WRIGHT. && $$ SHORT TERM...MS FEB 13 LONG TERM...DONAVON AVIATION...MS FEB 13
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1123 AM CST MON FEB 11 2013 .AVIATION... MVFR CONDITIONS WILL BE SEEN AT KCID/KDBQ/KMLI THROUGH SUNRISE BEFORE IMPROVING TO VFR. KDBQ MAY SEE SHSN THAT BRIEFLY LOWERS VSBYS. INTERNALLY...THE MODELS DO NOT SHOW ANY SIGNIFICANT SUBSIDENCE THAT WOULD HELP BREAK UP THE CLOUD COVER OVERNIGHT AND SATELLITE SHOWS EXTENSIVE CLOUDS BACK INTO THE DAKOTAS. WINDS WILL DECREASE THROUGH 00Z/12 AND SHOULD BE 10 KTS OR LESS AFTER SUNSET. HIGH PRESSURE BUILDING INTO THE MIDWEST AFT 12Z/12 SHOULD BREAK UP THE CLOUDS AND ALLOW VFR CONDITIONS WITH LIGHT WINDS. ..08.. && .PREV DISCUSSION... /ISSUED 1028 AM CST MON FEB 11 2013/ UPDATE... BASED ON SATELLITE TRENDS AND WHAT RECENT RAP TRENDS ARE SUGGESTING...CLOUDS SHOULD START BREAKING UP ACROSS THE SOUTHERN CWFA DURING THE AFTERNOON HOURS WHILE THEY REMAIN IN PLACE ACROSS THE NORTH. RAP TRENDS INDICATE LAPSE RATES WILL REMAIN QUITE STEEP THROUGH THE AFTERNOON BUT 925MB WINDS AND THE OVERALL GRADIENT DECREASES/RELAXES RESPECTIVELY. THE OVERALL WIND ADVISORY WILL REMAIN IN PLACE BASED ON THIS BUT WINDS SHOULD SLOWLY DECREASE FROM NOW THROUGH MID AFTERNOON. ..08.. PREV DISCUSSION... /ISSUED 238 AM CST MON FEB 11 2013/ SYNOPSIS... STRONG LOW PRESSURE WAS LOCATED OVER NORTHWEST WISCONSIN EARLY THIS MORNING. THE STRONG CYCLONIC FLOW AROUND THE LOW WAS SUPPORTING VERY WINDY CONDITIONS TO THE WEST AND SOUTHWEST. THE STRONGEST WINDS WERE OCCURRING NORTH OF I80 WHERE SUSTAINED SPEEDS WERE IN THE 30 TO 35 PLUS MPH RANGE WITH GUSTS OF 40 TO 50 MPH. SNOW SHOWERS WERE ALSO OCCURRING IN THE STRONG CYCLONIC FLOW. THE SHOWERS WERE REDUCING VISIBILITIES ALONG THE HIGHWAY 20 CORRIDOR TO MILE AT TIMES WHILE FURTHER SOUTH SCATTERED FLURRIES WERE OCCURRING. SHORT TERM...TODAY AND TONIGHT... VERY WINDY CONDITIONS WILL CONTINUE THROUGH MUCH OF THE DAY AS THE WISCONSIN LOW MOVES INTO SOUTHWEST ONTARIO BY LATE THIS AFTERNOON. MODELS ARE STILL SHOWING WEST WINDS AS HIGH A 50KTS THIS MORNING IN THE WELL MIXED SURFACE TO NEARLY 850MB LAYER WITH WINDS IN THIS LAYER DIMINISHING DURING DURING THE AFTERNOON. THIS SUPPORTS CONTINUING THE WIND ADVISORY THROUGH 21Z TODAY. EXPECT 40 TO 50 MPH GUSTS THIS MORNING THEN GRADUALLY DIMINISHING THIS AFTERNOON. THE STRONGEST WIND ARE EXPECTED TO OCCUR ALONG AND NORTH OF I80 THIS MORNING. WRAP AROUND SNOW SHOWERS WILL ALSO CONTINUE THROUGH THE DAY MAINLY NORTH OF HIGHWAY 30. SOME MINOR ACCUMULATIONS CAN/T BE RULED OUT...PROBABLY LESS THAN A HALF INCH. THE EDGE OF THE WRAP AROUND CLOUDS EXTENDS SOUTH INTO CENTRAL MO AND WEST THROUGH EASTERN NE EARLY THIS MORNING. THE BACK EDGE IN NE WAS CREEPING EAST AND CURRENT TIMING SUGGESTS IT COULD REACH SOUTHEAST IA THIS MORNING. HOWEVER...ANY CLEARING SHOULD BE BRIEF WITH CU/SC REDEVELOPING GIVEN THE STEEP LOW LEVEL LAPSE RATES. CLEARING SHOULD RESUME LATE THIS AFTERNOON AS THE CONVECTIVE CLOUDS DISSIPATE AND THE BETTER LOW LEVEL MOISTURE MOVES NORTHEAST. THIS EVENING THE SURFACE PRESSURE GRADIENT WILL CONTINUE TO RELAX AHEAD OF WEAK SURFACE RIDGE MOVING INTO CENTRAL IOWA. CLOUDS WILL ALSO MOVE NORTHEAST OF THE AREA DURING THE EVENING WITH CLEAR SKIES EXPECTED OVERNIGHT. WITH CLOUDS AND ONGOING COLD AIR ADVECTION WITH SHOULD SEE ABOUT A 10 DEGREE RECOVERY IN TEMPERATURES...PUTTING HIGHS MAINLY IN THE 30S. TONIGHT UPPER TEENS TO MID 20S LOOK REASONABLE WITH THE EXPECTED CLEARING AND DIMINISHING WIND. DLF LONG TERM...TUESDAY THROUGH SUNDAY... FORECAST FOCUS ON QUIET WEATHER EARLY TO MIDDLE PORTION OF THIS WEEK THEN TURNING COLDER LATE IN THE WEEK INTO NEXT WEEKEND. TUESDAY THROUGH THURSDAY...SPLIT FLOW ALLOWING FOR SOUTHERN STREAM STORM SYSTEM TO REMAIN UN-PHASED AS IT PUSHES QUICKLY INTO THE MID ATLANTIC STATES ON WEDNESDAY AND THEN OUT TO SEA. THIS SYSTEM COMBINED WITH A VERY INTENSE STORM IN THE GULF OF ALASKA PUMPS UP A FULL LATITUDE RIDGE FROM THE WEST COAST OF THE UNITED STATES INTO WESTERN CANADA. THIS BEGINS DEEPENING THE DOWNSTREAM TROUGH INTO THE NORTHERN PLAINS/UPPER MIDWEST BY THURSDAY. A STRONG COLD FRONT WILL BE PUSHING INTO THE DVN CWA ON THURSDAY BUT AHEAD OF THE FRONT TEMPERATURES WILL WARM UP INTO THE 40S ON WEDNESDAY. THURSDAY NIGHT AND FRIDAY...DEEPENING TROUGH IN THE EAST AND RIDGE IN THE ROCKIES WILL TAP ARCTIC AIR AND A RETURN TO COLDER WEATHER FOR THE MIDWEST. VERY COLD AIR ALOFT MAY ALLOW FOR AT LEAST SCATTERED SNOW SHOWERS. LOWS WILL BE IN THE TEENS NORTH AND 20S SOUTH WHILE HIGHS ON FRIDAY WILL BE ONLY IN THE 20S AT MOST LOCATIONS. THE LACK OF SNOW COVER ACROSS MUCH OF THE CWA WILL KEEP TEMPERATURES FROM REALLY TAKING A NOSE DIVE. FRIDAY NIGHT THROUGH SUNDAY...PROGRESSIVE PATTERN WILL PUSH THE EASTERN TROUGH FARTHER TO THE EAST BY SUNDAY WHILE RIDGE MOVES INTO THE PLAINS. TEMPERATURES SHOULD BEGIN TO MODERATE SOME BY SUNDAY. FRIDAY NIGHT AND SATURDAY LOOK TO BE QUITE COLD WITH LOWS DROPPING INTO THE SINGLE DIGITS NORTH AND TEENS SOUTH WHILE HIGHS ON SATURDAY WILL BE IN THE 20S. 850 MB TEMPERATURES DROP TO -18C IN PORTIONS OF THE CWA. ON SUNDAY...HIGHS SHOULD PUSH BACK INTO THE LOWER 30S IN OUR SOUTHERN COUNTIES BUT REMAINING IN THE 20S NORTH. HAASE && .DVN WATCHES/WARNINGS/ADVISORIES... IA...WIND ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR BENTON-BUCHANAN- CEDAR-CLINTON-DELAWARE-DES MOINES-DUBUQUE-HENRY IA-IOWA- JACKSON-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-LINN-LOUISA- MUSCATINE-SCOTT-VAN BUREN-WASHINGTON. IL...WIND ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR BUREAU-CARROLL- HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-MERCER- PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE. MO...WIND ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR CLARK-SCOTLAND. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1028 AM CST MON FEB 11 2013 .UPDATE... BASED ON SATELLITE TRENDS AND WHAT RECENT RAP TRENDS ARE SUGGESTING...CLOUDS SHOULD START BREAKING UP ACROSS THE SOUTHERN CWFA DURING THE AFTERNOON HOURS WHILE THEY REMAIN IN PLACE ACROSS THE NORTH. RAP TRENDS INDICATE LAPSE RATES WILL REMAIN QUITE STEEP THROUGH THE AFTERNOON BUT 925MB WINDS AND THE OVERALL GRADIENT DECREASES/RELAXES RESPECTIVELY. THE OVERALL WIND ADVISORY WILL REMAIN IN PLACE BASED ON THIS BUT WINDS SHOULD SLOWLY DECREASE FROM NOW THROUGH MID AFTERNOON. ..08.. && .PREV DISCUSSION... /ISSUED 538 AM CST MON FEB 11 2013/ AVIATION... DEEP LOW PRESSURE WILL MOVE FROM WESTERN WI INTO THE NORTHERN GREAT LAKES BY THIS MORNING. WEST TO NORTHWEST WINDS BEHIND THE DEPARTING LOW WILL CONTINUE TO BE VERY STRONG...WITH SUSTAINED WINDS OF 20 TO 30 KTS...GUSTING TO 35 TO 40KTS AT TIMES INTO THIS AFTERNOON. WINDS WILL DECREASE TO 20KTS...GUST 30 KTS AROUND SUNSET AND THEN TO AROUND 10KTS BY MIDNIGHT. FLURRIES OR POSSIBLE LIGHT SNOW SHOWERS ARE EXPECTED AROUND DBQ THROUGH THIS MORNING. VISIBILITIES COULD DROP TO 1 TO 2 MILES IN SOME OF THE HEAVIER SNOW SHOWERS. CLOUDS BASES WERE IN THE 3000 FT TO 3500 FT RANGE OVER THE SOUTHWEST HALF OF THE FORECAST AREA WITH BASES WITH RANGING FROM 1500 TO 3000 FT BASES TO THE NORTHEAST EARLY THIS MORNING. THE VFR CIGS SHOULD CONTINUE TO SPREAD EAST THIS MORNING WITH VFR CIGS EXPECTED OVER MUCH OF THE AREA BY 18Z. SKIES WILL BE CLEARING LATE THIS AFTERNOON AND EARLY THIS EVENING. DLF PREV DISCUSSION... /ISSUED 238 AM CST MON FEB 11 2013/ SYNOPSIS... STRONG LOW PRESSURE WAS LOCATED OVER NORTHWEST WISCONSIN EARLY THIS MORNING. THE STRONG CYCLONIC FLOW AROUND THE LOW WAS SUPPORTING VERY WINDY CONDITIONS TO THE WEST AND SOUTHWEST. THE STRONGEST WINDS WERE OCCURRING NORTH OF I80 WHERE SUSTAINED SPEEDS WERE IN THE 30 TO 35 PLUS MPH RANGE WITH GUSTS OF 40 TO 50 MPH. SNOW SHOWERS WERE ALSO OCCURRING IN THE STRONG CYCLONIC FLOW. THE SHOWERS WERE REDUCING VISIBILITIES ALONG THE HIGHWAY 20 CORRIDOR TO MILE AT TIMES WHILE FURTHER SOUTH SCATTERED FLURRIES WERE OCCURRING. SHORT TERM...TODAY AND TONIGHT... VERY WINDY CONDITIONS WILL CONTINUE THROUGH MUCH OF THE DAY AS THE WISCONSIN LOW MOVES INTO SOUTHWEST ONTARIO BY LATE THIS AFTERNOON. MODELS ARE STILL SHOWING WEST WINDS AS HIGH A 50KTS THIS MORNING IN THE WELL MIXED SURFACE TO NEARLY 850MB LAYER WITH WINDS IN THIS LAYER DIMINISHING DURING DURING THE AFTERNOON. THIS SUPPORTS CONTINUING THE WIND ADVISORY THROUGH 21Z TODAY. EXPECT 40 TO 50 MPH GUSTS THIS MORNING THEN GRADUALLY DIMINISHING THIS AFTERNOON. THE STRONGEST WIND ARE EXPECTED TO OCCUR ALONG AND NORTH OF I80 THIS MORNING. WRAP AROUND SNOW SHOWERS WILL ALSO CONTINUE THROUGH THE DAY MAINLY NORTH OF HIGHWAY 30. SOME MINOR ACCUMULATIONS CAN/T BE RULED OUT...PROBABLY LESS THAN A HALF INCH. THE EDGE OF THE WRAP AROUND CLOUDS EXTENDS SOUTH INTO CENTRAL MO AND WEST THROUGH EASTERN NE EARLY THIS MORNING. THE BACK EDGE IN NE WAS CREEPING EAST AND CURRENT TIMING SUGGESTS IT COULD REACH SOUTHEAST IA THIS MORNING. HOWEVER...ANY CLEARING SHOULD BE BRIEF WITH CU/SC REDEVELOPING GIVEN THE STEEP LOW LEVEL LAPSE RATES. CLEARING SHOULD RESUME LATE THIS AFTERNOON AS THE CONVECTIVE CLOUDS DISSIPATE AND THE BETTER LOW LEVEL MOISTURE MOVES NORTHEAST. THIS EVENING THE SURFACE PRESSURE GRADIENT WILL CONTINUE TO RELAX AHEAD OF WEAK SURFACE RIDGE MOVING INTO CENTRAL IOWA. CLOUDS WILL ALSO MOVE NORTHEAST OF THE AREA DURING THE EVENING WITH CLEAR SKIES EXPECTED OVERNIGHT. WITH CLOUDS AND ONGOING COLD AIR ADVECTION WITH SHOULD SEE ABOUT A 10 DEGREE RECOVERY IN TEMPERATURES...PUTTING HIGHS MAINLY IN THE 30S. TONIGHT UPPER TEENS TO MID 20S LOOK REASONABLE WITH THE EXPECTED CLEARING AND DIMINISHING WIND. DLF LONG TERM...TUESDAY THROUGH SUNDAY... FORECAST FOCUS ON QUIET WEATHER EARLY TO MIDDLE PORTION OF THIS WEEK THEN TURNING COLDER LATE IN THE WEEK INTO NEXT WEEKEND. TUESDAY THROUGH THURSDAY...SPLIT FLOW ALLOWING FOR SOUTHERN STREAM STORM SYSTEM TO REMAIN UN-PHASED AS IT PUSHES QUICKLY INTO THE MID ATLANTIC STATES ON WEDNESDAY AND THEN OUT TO SEA. THIS SYSTEM COMBINED WITH A VERY INTENSE STORM IN THE GULF OF ALASKA PUMPS UP A FULL LATITUDE RIDGE FROM THE WEST COAST OF THE UNITED STATES INTO WESTERN CANADA. THIS BEGINS DEEPENING THE DOWNSTREAM TROUGH INTO THE NORTHERN PLAINS/UPPER MIDWEST BY THURSDAY. A STRONG COLD FRONT WILL BE PUSHING INTO THE DVN CWA ON THURSDAY BUT AHEAD OF THE FRONT TEMPERATURES WILL WARM UP INTO THE 40S ON WEDNESDAY. THURSDAY NIGHT AND FRIDAY...DEEPENING TROUGH IN THE EAST AND RIDGE IN THE ROCKIES WILL TAP ARCTIC AIR AND A RETURN TO COLDER WEATHER FOR THE MIDWEST. VERY COLD AIR ALOFT MAY ALLOW FOR AT LEAST SCATTERED SNOW SHOWERS. LOWS WILL BE IN THE TEENS NORTH AND 20S SOUTH WHILE HIGHS ON FRIDAY WILL BE ONLY IN THE 20S AT MOST LOCATIONS. THE LACK OF SNOW COVER ACROSS MUCH OF THE CWA WILL KEEP TEMPERATURES FROM REALLY TAKING A NOSE DIVE. FRIDAY NIGHT THROUGH SUNDAY...PROGRESSIVE PATTERN WILL PUSH THE EASTERN TROUGH FARTHER TO THE EAST BY SUNDAY WHILE RIDGE MOVES INTO THE PLAINS. TEMPERATURES SHOULD BEGIN TO MODERATE SOME BY SUNDAY. FRIDAY NIGHT AND SATURDAY LOOK TO BE QUITE COLD WITH LOWS DROPPING INTO THE SINGLE DIGITS NORTH AND TEENS SOUTH WHILE HIGHS ON SATURDAY WILL BE IN THE 20S. 850 MB TEMPERATURES DROP TO -18C IN PORTIONS OF THE CWA. ON SUNDAY...HIGHS SHOULD PUSH BACK INTO THE LOWER 30S IN OUR SOUTHERN COUNTIES BUT REMAINING IN THE 20S NORTH. HAASE && .DVN WATCHES/WARNINGS/ADVISORIES... IA...WIND ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR BENTON-BUCHANAN- CEDAR-CLINTON-DELAWARE-DES MOINES-DUBUQUE-HENRY IA-IOWA- JACKSON-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-LINN-LOUISA- MUSCATINE-SCOTT-VAN BUREN-WASHINGTON. IL...WIND ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR BUREAU-CARROLL- HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-MERCER- PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE. MO...WIND ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR CLARK-SCOTLAND. && $$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
542 AM CST MON FEB 11 2013 ...UPDATED AVIATION DISCUSSION... .SHORT TERM /TODAY/... MAIN FORECAST CONCERN TODAY IS WITH WINDS...AND LIGHT SNOW SHOWERS/FZDZ ACROSS NORTHERN IOWA. VERTICALLY STACKED LOW WILL CONTINUE TO PUSH EASTWARD THROUGH THE DAY AND PRESSURE GRADIENT BEGINS TO RELAX DURING THE AFTERNOON HOURS. NAM/GFS BUFR SOUNDINGS SUGGEST SOME LIGHT SNOW SHOWERS OR FLURRIES OVER NORTHERN IOWA THROUGH 18Z BUT RAP SHOWING LOSS OF ICE INTRODUCTION IN THE COLUMN PERIODICALLY DURING THE MORNING. SEVERAL CURRENT OBSERVATIONS ACROSS NORTHERN IOWA REPORTING DZ/UP SUGGESTING THIS IS ALREADY OCCURRING. FORCING REMAINS WEAK BUT LOOKS TO BE ENOUGH TO WARRANT THE MENTION OF PATCHY FZDZ ACROSS THE NORTHEAST THROUGH 18Z. WENT CLOSE TO GUIDANCE TODAY FOR MAX TEMPERATURES AS MODELS ARE IN GOOD AGREEMENT AND FELT NO REASON TO DEVIATE MUCH FROM THEM. THIS RESULTED IN TWEAKING TEMPS UP SLIGHTLY ACROSS THE SOUTH. NOT EXPECTING STRATUS TO CLEAR OUT ACROSS THE SOUTHWEST UNTIL AFTER 21Z WHEN THE PRESSURE GRADIENT BEGINS TO WEAKEN. KEPT OVERCAST OVER THE NORTH TO EAST THROUGH 00Z TUESDAY AS LOW LEVEL MOISTURE REMAINS PERSISTENT WITHIN THE CAA. .LONG TERM /TONIGHT THROUGH SUNDAY/... THE UPPER LOW PRESSURE WILL CONTINUE TO RACE OFF TO THE EAST TONIGHT AND BE NEAR MAIN BY 12Z TUESDAY MORNING. THIS WILL ALLOW MUCH DRIER AIR TO FILTER INTO THE STATE AS BROAD AREA OF HIGH PRESSURE SHIFTS EAST INTO THE MIDWEST. GENERAL TRENDS FOR TUESDAY AND WEDNESDAY ARE WARMER. THE DRY AIR WILL WARM NICELY ON TUESDAY UNDER SOUTHWEST FLOW. THE FLOW WILL BECOME MORE DOWN SLOPE ORIENTED TUESDAY NIGHT INTO WEDNESDAY AHEAD A VIGOROUS UPPER WAVE THAT WILL ARRIVE ALONG WITH AN ASSOCIATED COLD FRONT WEDNESDAY NIGHT. TEMPERATURES ON WEDNESDAY WILL BE IN THE MID TO UPPER 40S OVER THE CENTRAL AND SOUTH AND A FEW LOCATIONS MAY HIT 50 IF ENOUGH SUN IS AVAILABLE. THE UPPER WAVE WILL PASS THROUGH WEDNESDAY NIGHT INTO THURSDAY. GUSTY NORTHWEST WINDS WILL KEEP COLD ADVECTION IN PLACE THROUGH THE DAY THURSDAY AND MAY HAVE SLOWLY FALLING TEMPERATURES DURING THE AFTERNOON. THE AIR MASS WITH THE SYSTEM WILL BE FAIRLY DRY WITH PWATS GENERALLY ONE QUARTER INCH OR LESS THEREFORE NO PRECIPITATION IS EXPECTED. ANOTHER UPPER WAVE WILL DROP INTO THE REGION THURSDAY NIGHT AND FRIDAY AND WILL HELP CARVE A LONG WAVE TROUGH OUT ACROSS THE NORTHERN PLAINS AND INTO THE EASTERN CONUS. THIS WILL BE ENHANCED AS HUDSON BAY UPPER LOW DROPS SOUTH INTO THE UPPER GREAT LAKES. 850 MB TEMPERATURES OVER THE STATE WILL BE AROUND -16C BY MID DAY FRIDAY. THE COLD AIR MASS WILL BE RELATIVELY DEEP AND WILL BE ABLE TO MIX WELL. THEREFORE DESPITE THE COLD AIR MASS...DEEP MIXING TO NEAR 850 MB WILL ALLOW TEMPERATURES RISE INTO THE UPPER TEENS TO UPPER 20S. SATURDAY AND SUNDAY WILL SEE GRADUAL MODERATION AS A WEAK RIDGE MOVES INTO THE STATE IN RESPONSE TO A STRONG SHORT WAVE DIVING INTO THE INTER MOUNTAIN WEST. && .AVIATION...11/12Z TIGHT PRESSURE GRADIENT WILL CONTINUE TO PRODUCE VERY WINDY CONDITIONS THROUGH THE DAY BEFORE WINDS DIMINISH PAST 00Z TUESDAY AS THE LOW MOVES EAST AND ALLOW THE GRADIENT TO WEAKEN. OCCASIONAL -SN WILL PERSIST THROUGH MIDDAY AFFECTING MAINLY MCW/ALO WITH IFR VIS AT TIMES. MVFR STRATUS IS LIKELY TO PERSIST THROUGH MUCH OF THE DAY AS WELL. && .DMX WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL NOON CST TODAY FOR IAZ004>007-015>017- 023>028-033>039-044>050-057>062-074-075-086. && $$ SHORT TERM...PODRAZIK LONG TERM...DONAVON AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
357 AM CST MON FEB 11 2013 .SHORT TERM /TODAY/... MAIN FORECAST CONCERN TODAY IS WITH WINDS...AND LIGHT SNOW SHOWERS/FZDZ ACROSS NORTHERN IOWA. VERTICALLY STACKED LOW WILL CONTINUE TO PUSH EASTWARD THROUGH THE DAY AND PRESSURE GRADIENT BEGINS TO RELAX DURING THE AFTERNOON HOURS. NAM/GFS BUFR SOUNDINGS SUGGEST SOME LIGHT SNOW SHOWERS OR FLURRIES OVER NORTHERN IOWA THROUGH 18Z BUT RAP SHOWING LOSS OF ICE INTRODUCTION IN THE COLUMN PERIODICALLY DURING THE MORNING. SEVERAL CURRENT OBSERVATIONS ACROSS NORTHERN IOWA REPORTING DZ/UP SUGGESTING THIS IS ALREADY OCCURRING. FORCING REMAINS WEAK BUT LOOKS TO BE ENOUGH TO WARRANT THE MENTION OF PATCHY FZDZ ACROSS THE NORTHEAST THROUGH 18Z. WENT CLOSE TO GUIDANCE TODAY FOR MAX TEMPERATURES AS MODELS ARE IN GOOD AGREEMENT AND FELT NO REASON TO DEVIATE MUCH FROM THEM. THIS RESULTED IN TWEAKING TEMPS UP SLIGHTLY ACROSS THE SOUTH. NOT EXPECTING STRATUS TO CLEAR OUT ACROSS THE SOUTHWEST UNTIL AFTER 21Z WHEN THE PRESSURE GRADIENT BEGINS TO WEAKEN. KEPT OVERCAST OVER THE NORTH TO EAST THROUGH 00Z TUESDAY AS LOW LEVEL MOISTURE REMAINS PERSISTENT WITHIN THE CAA. .LONG TERM /TONIGHT THROUGH SUNDAY/... THE UPPER LOW PRESSURE WILL CONTINUE TO RACE OFF TO THE EAST TONIGHT AND BE NEAR MAIN BY 12Z TUESDAY MORNING. THIS WILL ALLOW MUCH DRIER AIR TO FILTER INTO THE STATE AS BROAD AREA OF HIGH PRESSURE SHIFTS EAST INTO THE MIDWEST. GENERAL TRENDS FOR TUESDAY AND WEDNESDAY ARE WARMER. THE DRY AIR WILL WARM NICELY ON TUESDAY UNDER SOUTHWEST FLOW. THE FLOW WILL BECOME MORE DOWN SLOPE ORIENTED TUESDAY NIGHT INTO WEDNESDAY AHEAD A VIGOROUS UPPER WAVE THAT WILL ARRIVE ALONG WITH AN ASSOCIATED COLD FRONT WEDNESDAY NIGHT. TEMPERATURES ON WEDNESDAY WILL BE IN THE MID TO UPPER 40S OVER THE CENTRAL AND SOUTH AND A FEW LOCATIONS MAY HIT 50 IF ENOUGH SUN IS AVAILABLE. THE UPPER WAVE WILL PASS THROUGH WEDNESDAY NIGHT INTO THURSDAY. GUSTY NORTHWEST WINDS WILL KEEP COLD ADVECTION IN PLACE THROUGH THE DAY THURSDAY AND MAY HAVE SLOWLY FALLING TEMPERATURES DURING THE AFTERNOON. THE AIR MASS WITH THE SYSTEM WILL BE FAIRLY DRY WITH PWATS GENERALLY ONE QUARTER INCH OR LESS THEREFORE NO PRECIPITATION IS EXPECTED. ANOTHER UPPER WAVE WILL DROP INTO THE REGION THURSDAY NIGHT AND FRIDAY AND WILL HELP CARVE A LONG WAVE TROUGH OUT ACROSS THE NORTHERN PLAINS AND INTO THE EASTERN CONUS. THIS WILL BE ENHANCED AS HUDSON BAY UPPER LOW DROPS SOUTH INTO THE UPPER GREAT LAKES. 850 MB TEMPERATURES OVER THE STATE WILL BE AROUND -16C BY MID DAY FRIDAY. THE COLD AIR MASS WILL BE RELATIVELY DEEP AND WILL BE ABLE TO MIX WELL. THEREFORE DESPITE THE COLD AIR MASS...DEEP MIXING TO NEAR 850 MB WILL ALLOW TEMPERATURES RISE INTO THE UPPER TEENS TO UPPER 20S. SATURDAY AND SUNDAY WILL SEE GRADUAL MODERATION AS A WEAK RIDGE MOVES INTO THE STATE IN RESPONSE TO A STRONG SHORT WAVE DIVING INTO THE INTER MOUNTAIN WEST. && .AVIATION...11/06Z AREAS OF LIGHT SNOW WILL PERSIST ACROSS NORTHERN IOWA OVERNIGHT WITH A FEW FLURRIES IN THE SOUTH. VISIBILITIES WILL BE MVFR TO IFR IN THE NORTH WITH THE LIGHT SNOW BUT SHOULD IMPROVE TO VFR ON MONDAY AS THE PCPN ENDS. CEILINGS WILL REMAIN IN PLACE THROUGH MUCH OF MONDAY ACROSS THE FORECAST AREA WITH MVFR CEILINGS IN THE NORTH AND VFR CONDITIONS IN THE SOUTH. TIGHT PRESSURE GRADIENT WILL MAINTAIN STRONG WEST TO NORTHWEST WINDS OVERNIGHT INTO MONDAY BEFORE A GRADUAL WEAKENING INTO MONDAY EVENING AS THE GRADIENT RELAXES. && .DMX WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL NOON CST TODAY FOR IAZ004>007-015>017- 023>028-033>039-044>050-057>062-074-075-086. && $$ SHORT TERM...PODRAZIK LONG TERM...DONAVON AVIATION...COGIL
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1230 PM EST MON FEB 11 2013 ...Updated Aviation Discussion... .Forecast Update... Issued at 1040 AM EST Mon Feb 11 2013 Ran a quick update this morning mainly to increase cloud cover across the southeast. A rather thick upper level deck looks as if it will stream across the Cumberland area through much of the day as another wave rides up along the departing frontal boundary. Also tweaked temperature and dewpoint grids to account for current trends. The jury is still out on the decision for an advisory late this morning into this afternoon. Louisville (SDF) gusted to 36 mph earlier this morning and Frankfort just recently gusted to 37 mph. However, both the 12Z NAM and the latest RAP soundings continue to advertise only about 35 knots at the top of the mixed layer late this morning, staying nearly steady or slowly weakening through the afternoon despite a deepening mixed layer. Will continue to monitor observations over the next few hours, but current thinking is that this event will best be handled with an SPS (although an isolated 40 mph gust is certainly possible). && .Short Term (Today - Tuesday)... Issued at 315 AM EST Mon Feb 11 2013 Light showers/drizzle redeveloped late last night and early this morning. This is currently in the process of exiting the forecast area, with dry air and reduced cloud cover working into the region. A vertically stacked low pressure system will meander eastward across the Great Lakes today. This will set up a tight pressure gradient at the surface, with even stronger winds aloft. Partly to mostly sunny skies and cold air advection aloft will aid mixing those winds to the surface. Sustained speeds between 15 and 25 mph are expected, with some gusts near 40 mph possible. Southern Indiana and north-central Kentucky will experience the strongest winds, with slightly weaker winds across south-central Kentucky. The peak period for the strongest winds will be from about mid morning through the afternoon. Wind speeds will decrease this evening, as the pressure gradient relaxes with surface high pressure and ridging aloft taking control. The high temperature forecast for today is tricky, with the ongoing cold air advection. We remained quite mild overnight, but cooler air is approaching from the west. Believe highs in the mid to upper 40s will be possible across southern Indiana, with lower 50s across north-central Kentucky and mid 50s across south-central and east-central Kentucky. Some of these highs, particularly in the north, may occur this morning and hold steady or only increase a degree or two with solar heating this afternoon. Lows tonight will drop into the upper 20s and lower 30s, with mostly clear skies. Typical cooler locations could dip into the mid 20s. Expect dry conditions, light westerly winds and temperatures ranging from the mid 40s to low 50s Tuesday. Clouds will increase through the day, ahead of our next system. .Long Term (Tuesday Night - Sunday)... Issued at 300 AM EST Mon Feb 11 2013 ...Light Wintry Precip Possible Wednesday Morning... The main concern in the long term period will be the possibility of light wintry precip Wed morning as an upper trough moves through the Ohio Valley. Still quite a bit of model spread on the track of the QPF field as it passes through our region, but have sided with a track similar to the 0Z GFS, GFS ensembles, and GEM. The 0Z ECMWF looks too suppressed compared to previous model runs and the 0Z NAM is much farther north than previous model runs. Certainly going with a consistency forecast here on the track of precipitation. One common theme among 0Z model guidance regardless of track is the slower timing of this weather system through the region. This theme combined with very dry low layers at onset of precip were evidence enough to delay precip arrival by around 4-6 hrs from the previous forecast. Looks like we should see some virga entering the region by around midnight Tues night, but precip shouldn`t start reaching the ground until closer to sunrise with the best coverage during the late morning/early afternoon hours Wed. Precipitation will be quick hitting and on its way out by late afternoon or early evening Wed. As far as precip type, boundary layer temps will be our determining factor as it looks like we`ll see ice crystal growth aloft with the main slug of moisture. With mild antecedent air and ground temps, think that most of the precip should fall as a cold rain. However, thermal profiles indicate that southern Indiana and north central KY may be cold enough Wed morning in a 2-5 hr window around sunrise for some snowflakes to fall. Also models do indicate some weak deformation with this system so if some heavier bands of precip set up in an environment with boundary layer temps close to freezing, we could see a change over to all snow briefly in heavier bands. Still with ground temps running in the lower 40s and low temps expected in the lower 30 to mid 30s across the area, think that any light snow accums would be short lived and shouldn`t cause much of a travel issue. Still stay abreast of the forecast for Wed morning`s commute as any changes in the thermal profile will affect ptype and potentially travel impacts. High temps on Wed are expected to top out in the lower 40s. Expect dry conditions for Thurs as zonal flow will dominate our region while a potent trough digs across the Plains states. This trough will push into the Midwest for the weekend creating a cool down. We`ll go from highs in the 40s to around 50 Thurs/Fri. to highs in the 30s Sat/Sun. Although no big weather makers look to impact the Ohio Valley with this upper trough, we will keep 20% POPs in the forecast as hard to time shortwaves that may produce light precip look possible Fri/Sat. && .Aviation (18Z TAF Issuance)... Issued at 1230 PM EST Mon Feb 11 2013 VFR conditions will prevail through the TAF period. The main issue over the next several hours will continue to be strong winds, as an area of low pressure pushes east through the Great Lakes. Expect westerly winds to continue at 15-20 knots, with gusts approaching 30 knots for the remainder of the afternoon across KLEX and KSDF. Winds will be slightly lower at KBWG, with 10-15 knots sustained and gusts just above 20 knots. Otherwise, winds will die down this evening, becoming variable by Tuesday as a surface ridge slides through the Ohio Valley. Some high clouds will begin to approach from the southwest toward the end of the TAF period in advance of the next system. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Update...........KD Short Term.......MJP Long Term........AMS Aviation.........KD
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1040 AM EST MON FEB 11 2013 .Forecast Update... Issued at 1040 AM EST Mon Feb 11 2013 Ran a quick update this morning mainly to increase cloud cover across the southeast. A rather thick upper level deck looks as if it will stream across the Cumberland area through much of the day as another wave rides up along the departing frontal boundary. Also tweaked temperature and dewpoint grids to account for current trends. The jury is still out on the decision for an advisory late this morning into this afternoon. Louisville (SDF) gusted to 36 mph earlier this morning and Frankfort just recently gusted to 37 mph. However, both the 12Z NAM and the latest RAP soundings continue to advertise only about 35 knots at the top of the mixed layer late this morning, staying nearly steady or slowly weakening through the afternoon despite a deepening mixed layer. Will continue to monitor observations over the next few hours, but current thinking is that this event will best be handled with an SPS (although an isolated 40 mph gust is certainly possible). && .Short Term (Today - Tuesday)... Issued at 315 AM EST Mon Feb 11 2013 Light showers/drizzle redeveloped late last night and early this morning. This is currently in the process of exiting the forecast area, with dry air and reduced cloud cover working into the region. A vertically stacked low pressure system will meander eastward across the Great Lakes today. This will set up a tight pressure gradient at the surface, with even stronger winds aloft. Partly to mostly sunny skies and cold air advection aloft will aid mixing those winds to the surface. Sustained speeds between 15 and 25 mph are expected, with some gusts near 40 mph possible. Southern Indiana and north-central Kentucky will experience the strongest winds, with slightly weaker winds across south-central Kentucky. The peak period for the strongest winds will be from about mid morning through the afternoon. Wind speeds will decrease this evening, as the pressure gradient relaxes with surface high pressure and ridging aloft taking control. The high temperature forecast for today is tricky, with the ongoing cold air advection. We remained quite mild overnight, but cooler air is approaching from the west. Believe highs in the mid to upper 40s will be possible across southern Indiana, with lower 50s across north-central Kentucky and mid 50s across south-central and east-central Kentucky. Some of these highs, particularly in the north, may occur this morning and hold steady or only increase a degree or two with solar heating this afternoon. Lows tonight will drop into the upper 20s and lower 30s, with mostly clear skies. Typical cooler locations could dip into the mid 20s. Expect dry conditions, light westerly winds and temperatures ranging from the mid 40s to low 50s Tuesday. Clouds will increase through the day, ahead of our next system. .Long Term (Tuesday Night - Sunday)... Issued at 300 AM EST Mon Feb 11 2013 ...Light Wintry Precip Possible Wednesday Morning... The main concern in the long term period will be the possibility of light wintry precip Wed morning as an upper trough moves through the Ohio Valley. Still quite a bit of model spread on the track of the QPF field as it passes through our region, but have sided with a track similar to the 0Z GFS, GFS ensembles, and GEM. The 0Z ECMWF looks too suppressed compared to previous model runs and the 0Z NAM is much farther north than previous model runs. Certainly going with a consistency forecast here on the track of precipitation. One common theme among 0Z model guidance regardless of track is the slower timing of this weather system through the region. This theme combined with very dry low layers at onset of precip were evidence enough to delay precip arrival by around 4-6 hrs from the previous forecast. Looks like we should see some virga entering the region by around midnight Tues night, but precip shouldn`t start reaching the ground until closer to sunrise with the best coverage during the late morning/early afternoon hours Wed. Precipitation will be quick hitting and on its way out by late afternoon or early evening Wed. As far as precip type, boundary layer temps will be our determining factor as it looks like we`ll see ice crystal growth aloft with the main slug of moisture. With mild antecedent air and ground temps, think that most of the precip should fall as a cold rain. However, thermal profiles indicate that southern Indiana and north central KY may be cold enough Wed morning in a 2-5 hr window around sunrise for some snowflakes to fall. Also models do indicate some weak deformation with this system so if some heavier bands of precip set up in an environment with boundary layer temps close to freezing, we could see a change over to all snow briefly in heavier bands. Still with ground temps running in the lower 40s and low temps expected in the lower 30 to mid 30s across the area, think that any light snow accums would be short lived and shouldn`t cause much of a travel issue. Still stay abreast of the forecast for Wed morning`s commute as any changes in the thermal profile will affect ptype and potentially travel impacts. High temps on Wed are expected to top out in the lower 40s. Expect dry conditions for Thurs as zonal flow will dominate our region while a potent trough digs across the Plains states. This trough will push into the Midwest for the weekend creating a cool down. We`ll go from highs in the 40s to around 50 Thurs/Fri. to highs in the 30s Sat/Sun. Although no big weather makers look to impact the Ohio Valley with this upper trough, we will keep 20% POPs in the forecast as hard to time shortwaves that may produce light precip look possible Fri/Sat. && .Aviation (12Z TAF Issuance)... Issued at 620 AM EST Mon Feb 11 2013 Expect VFR conditions at all TAF sites this forecast period. Could see a few Cu at the top of a relatively deep mixing layer later this afternoon, along with a some high clouds from a southern stream system. However, the big issue today will be gusty west winds. Winds will continue a transition to west-southwest and be quite gusty, as the pressure gradient strengthens with a vertically stacked low meandering east across the Great Lakes. Wind speeds will peak just over 20 knots at BWG and just over 30 knots at SDF and LEX. Gusts should settle down around sunset, with speeds decreasing overnight as high pressure takes control. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Update...........KD Short Term.......MJP Long Term........AMS Aviation.........MJP
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1228 AM EST MON FEB 11 2013 ...Updated Aviation Discussion... .Forecast Update... Issued at 910 PM EST Sun Feb 10 2013 Not seeing much to increase forecast confidence as the evening wears on. Precip development has been limited at best, but the mesoscale models continue to generate chance POPs later this evening. Might otherwise be inclined to drastically lower POPs with this evening update, but the RUC and HRRR both seem to have a handle on what is out there now, and start to show development near the I-65 corridor around 03-04Z. Already updated to clean up evening wording and remove thunder, and lowered POPs to chance at that time. Otherwise the forecast has been left as-is and most tweaks for the rest of the evening will be in the grids. && .Short Term (Tonight - Monday Night)... Issued at 300 PM EST Sun Feb 10 2013 A vertically stacked low continues to churn across the Central Plains this afternoon. Out ahead of this low, a ridge has amplified over the Ohio Valley, allowing a warm and rather moist airmass to push north into the Ohio Valley. Showers and embedded thunderstorms have pushed into the western half of the CWA this afternoon. A notable weakening trend has occurred with this activity over the past few hours as it has pushed east, due to it outrunning the better elevated instability and the strongest forcing pushing north. This weakening trend will continue through the remainder of the afternoon, but much of the area still has a chance of seeing an isolated thunderstorm as the main line pushes east. Winds out ahead of this line have been breezy, especially across areas that received a break in the clouds early this afternoon. Simpson County for example, gusted to 37 knots as they broke out in some sunshine. However, winds should continue to slowly slacken as this system rolls through and saturates the column, limiting any mixing. Some of the stronger convection has mixed down some higher momentum air this afternoon, but the potential for any damaging gusts appears very low as a stout cap remains in place. After the main line rolls through late this afternoon into the early evening, attention will then turn to the southwest as another weak shortwave ejects out of the southwest flow aloft. Most high-res models are indicating some low-topped convective showers developing along the surface front as this wave rides up along it tonight. Therefore, will increase pops once again this evening into tonight to account for these showers. The surface front will clear the area and dry air will work into the region by Monday morning. The only issue on Monday will be the gusty wind potential, especially across southern Indiana and the northern Bluegrass. Currently have winds gusting to around 35 MPH during the afternoon hours, as mostly sunny skies and cold air advection aloft helps aid in mixing. These gusts are just below advisory criteria and the potential for an advisory across the northern CWA will need to be revisited in coming forecasts. With the expected deep mixing and a good amount of sunshine, have gone a bit above guidance for highs on Monday (upper 40s to middle 50s). Winds will begin to die down Monday night as a surface ridge pushes into the region. Lows Monday night will drop into the upper 20s and lower 30s, with mostly clear skies. .Long Term (Tuesday - Sunday)... Issued at 255 PM EST Sun Feb 10 2013 The first concern in the long term is, of course, the Tuesday night/Wednesday system. Looking at the models, the EC has had slightly better run-to-run consistency than the GFS, especially on Wednesday, with the path of the surface low that will be going by to our south Tuesday night/Wednesday. The EC also has been leading the way with verification of surface temperatures and dew points lately. Still, the EC isn`t perfect and it looks like the model is probably ejecting the low eastward too quickly. We will also need to dial in a bit of a northward correction to account for the possibility that the models might be taking this southern stream system a bit too far south. So, given all that, will go with a surface low path from Louisiana Tuesday evening to between Birmingham and Atlanta Wednesday morning to the VA/NC coast Wednesday evening. The upper trof associated with this system is a narrow appendage poking southwestward from the main upper trof well to our north. As a result it is quite far away from the polar vortex over the Canadian Archipelago and so there isn`t much cold air for this system to work with. So, despite the favorable track of the low to give us a snowstorm, it looks like we son`t have the requisite cold air and we should actually see rain in the south and a mix in the north. Of course, for a snowstorm one also needs a rich source of moisture. The GFS`s QPF is getting no real support from the EC, GEM, HPC, or GEFS and there is quite a bit of spread among the perturbation plumes in the GEFS (and SREF for that matter). So, won`t latch on to the GFS`s robust QPF numbers at this time and instead will go with more conservative amounts. Also supporting lower QPF values is a layer of surface-700hPa dry air that will have to be overcome Tuesday night before precipitation reaches the surface. In addition, the GFS tends to count virga as QPF. In the grids we have gone with 24-hour totals Tuesday night-Wednesday ranging from around a tenth of an inch in the north to a quarter of an inch far south. Even in the north where some snow will be possible, only a portion of that QPF will be snow. Ground temperatures will be warm from temperatures in the 45-50 degree range Tuesday afternoon, and highs Wednesday afternoon should get up to around 40. So, other than maybe a few tricky hours around the Wednesday morning commute, overall this system shouldn`t be too bad. Of course, we`ll need to keep an eye on it and the forecasts will surely evolve as we get closer to Tuesday night. A large upper trof will then dig into the Plains late in the week and invade the eastern half of the country over the weekend. This trof will have a direct connection to the main upper low over the Canadian Arctic and so will bring in colder air. Most of the precipitation associated with this trof will remain to our north in areas of better relative humidity and upper support. The best chance for precipitation for us will likely be with shortwave trofs diving down the backside of the trof. Those types of small-scale features are very difficult to accurately forecast so far out in the future, so will keep PoPs low at this time. Our warmest day should be Thursday with highs around 50. Once the late week upper trof comes in it will drop daily highs down into the 30s for the weekend. By Sunday morning we`ll probably dip into the teens, which is about ten degrees below normal for mid February. && .Aviation (06Z TAF Issuance)... Issued at 1228 AM EST Mon Feb 11 2013 Last little bit of light rain/drizzle is pushing into east-central KY. This will only impact LEX with lower cigs, which were experienced upstream. The back edge of the 1000-1500ft AGL cigs is currently across southern IL and western KY. If timed correctly, this should get into SDF and BWG within a couple of hours, and reach LEX around 10Z. All sites will improve to VFR, with breezy winds overnight keeping the atmosphere mixed. Expect mainly scattered Cu or Sc at the top of a relatively deep mixing layer later this afternoon. Winds will transition to west-southwest and be quite gusty, as a vertically stacked low meanders east across the Great Lakes today. Wind speeds will peak over 20 knots at BWG and perhaps just over 30 knots at SDF and LEX. Gusts should settle down around sunset, with speeds decreasing overnight as high pressure takes control. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Update...........RAS Short Term.......KD Long Term........13 Aviation.........MJP
AREA FORECAST DISCUSSION...CORRECTION TO ADD AVIATION
NWS SHREVEPORT LA
146 AM CST MON FEB 11 2013 .UPDATE... KSHV 88D SHOWING SOME LIGHT RAIN ALONG I-20 FROM TYLER...CONFIRMED WITH ASOS...TO STILL VIRGA OVER LONGVIEW AND JUST SOUTH OF TEXARKANA. THE WATER VAPOR IMAGERY SHOWS A SPEED MAX OVER MEXICO...NEARING THE RIO GRANDE...BRINGING A BIT OF LIFT OVER NE TX BACK OVER THE COLD FRONT. WE HAVE UPDATED 6-12Z AND 12-18Z POP AND WEATHER GRIDS WITH LIGHT RAIN NORTH...AS T/TD SPREADS ARE STILL PRETTY HARDY AND WE WILL CONTINUE WITH OUR CHANCE SHOWERS IN THE FRONTAL VICINITY ALONG AND SOUTH OF I-20. NO OTHER CHANGES ATTM. /24/ && .AVIATION... MOSTLY VFR FLIGHT CATEGORIES EXPECTED THROUGH THE EARLY MORNING HOURS AROUND 11/14 UTC BUT WITH LIGHT RAIN OR EMBEDDED SHOWERS SPREADING RAPIDLY WEST TO EAST. CEILINGS WILL BE RUNNING AROUND 7 KFT TO 10 KFT WITH SOME LOWERING OF CLOUDS AT TIMES TO NEAR 5 KFT. ALL OF THE TERMINAL SITES ALONG AND SOUTH OF INTERSTATE 20 LOOK TO BE AFFECTED BY THE RAIN OR SHOWERS WITH VISIBILITIES NEAR 6 STATUTE MILES OR MORE THROUGH 11/14 UTC. THE CLOUD BASE WILL BE GRADUALLY LOWERING...TRANSITIONING TO MVFR/IFR NEAR MID DAY TO EARLY AFTERNOON...AND REMAINING AT THE LOWER CATEGORIES THROUGH THE END OF THE TERMINAL FORECAST PERIOD ENDING AROUND 12/06 UTC AND LIKELY TO 12/12 UTC. TERMINAL FORECAST FOR KTXK AND KELD WILL BE MORE LIKELY TO REMAIN AT VFR UNTIL 12/06 UTC. SURFACE WIND LIGHT AND VARIABLE OR NORTHERLY LESS THAN 7 KNOTS UNTIL AFTER 11/15 UTC WHEN THE WINDS BECOME NORTHEAST TO EAST 7 TO 11 KNOTS. WINDS WILL LOWER SLIGHTLY AFTER 12/00 UTC BUT REMAIN AROUND 6 TO 9 KNOTS. /06/ && .PREV DISCUSSION... /ISSUED 920 PM CST SUN FEB 10 2013/ DISCUSSION... SURFACE ANALYSIS THIS EVENING INDICATED THAT OUR FRONTAL BOUNDARY WAS STALLED NEAR A MEM...MLU...LCH LINE. MUCH DRIER AIR IN THE LOWER LEVELS OF THE ATMOSPHERE HAS INFILTRATED THE REGION FROM THE WEST BUT STILL DEALING WITH A FAIRLY MOIST PROFILE ACROSS OUR EXTREME EASTERN ZONES. ALSO BEGINNING TO SEE SOME REDEVELOPMENT OF WIDELY SCATTERED SHOWERS ACROSS OUR EXTREME EASTERN ZONES AS WELL. FOR THIS REASON...HAVE LEFT POPS PRETTY MUCH UNCHANGED THROUGH THE NIGHT ADVERTISING CHANCE POPS TO OUR SOUTH AND EAST. A QUICK LOOK AT THE 00Z NAM AS WELL AS THE LATEST RAP SHOWS THAT SCATTERED SHOWERS WILL BE POSSIBLE ALL NIGHT...MAINLY ACROSS OUR SOUTHEAST ZONES. THESE MODELS ALSO SUGGEST THAT THE FRONTAL BOUNDARY WILL FINALLY GET SHOVED SOUTH AND EAST OVERNIGHT WHICH WILL ALLOW FOR SOME DRIER AIR TO PUSH THROUGH AT LEAST OUT EASTERN MOST ZONES. HOWEVER...MID AND HIGH LEVEL CLOUDS SHOULD HANG ON FOR THE REMAINDER OF THE NIGHT ACROSS ALL BUT OUR EXTREME NW ZONES. DESPITE THE DRIER AIR...FEEL LIKE THE CLOUD COVER SHOULD HOLD TEMPS UP SOMEWHAT OVERNIGHT. MOS GUIDANCE WAS RUNNING A LITTLE TOO COOL WITH ITS 03Z TEMPS ACROSS A FEW SELECTED CITIES THIS EVENING SO HAVE BUMPED UP OVERNIGHT MINS JUST A DEGREE OR TWO ACROSS A FEW LOCATIONS. DID MAKE SOME ADJUSTMENTS TO DEWPOINTS GIVEN THE SLOWER INFILTRATION OF DRIER AIR INTO OUR EASTERN ZONES THIS EVENING AND SOME COSMETIC CHANGES TO SKY GRIDS. OTHERWISE...NO OTHER CHANGES WERE NECESSARY THIS EVENING. UPDATE OUT SHORTLY...13. AVIATION... MOSTLY VFR FLIGHT WEATHER TONIGHT AND MONDAY. HOWEVER...AREAS SOUTH AND EAST OF A KMLU TO KLFK LINE WILL EXPERIENCE LOW VFR CIGS... BETWEEN 4 AND 6 KFT...WITH ISOLATED SHOWERS AND TSTMS. EXPECT SOME BRIEF VISIBILITY RESTRICTIONS TO NEAR IFR IN THE STRONGER CONVECTION. THIS AREA OF LOW VFR CIGS AND CONVECTION WILL GRADUALLY SPREAD TO THE NORTH ON MONDAY...TO NEAR A KELD TO KTYR LINE BY 12/00Z. SURFACE WIND LIGHT AND VARIABLE TONIGHT...AND NORTHEAST 5 TO 10 KTS MONDAY. /14/ && .PRELIMINARY POINT TEMPS/POPS... SHV 49 61 46 57 40 / 20 20 50 60 20 MLU 51 59 46 55 41 / 40 40 50 60 40 DEQ 35 61 38 49 34 / 20 20 30 60 40 TXK 42 63 44 51 36 / 20 20 40 60 30 ELD 44 61 43 54 37 / 20 20 40 60 40 TYR 48 61 46 55 37 / 20 20 60 60 20 GGG 49 62 46 55 38 / 20 20 60 60 20 LFK 52 63 50 60 41 / 30 40 60 60 20 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...NONE. LA...NONE. OK...NONE. TX...NONE. && $$ 24/06
AREA FORECAST DISCUSSION
NWS GAYLORD MI
930 PM EST TUE FEB 12 2013 .SYNOPSIS... ISSUED AT 415 PM EST TUE FEB 12 2013 WEAK HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT LAKES TONIGHT AND WEDNESDAY. THIS PATTERN WILL GENERATE ABOVE NORMAL TEMPERATURES AND OCCASIONAL FLURRIES...ACROSS THE NORTHERN MICHIGAN INTO THURSDAY. HOWEVER...THE NEXT SYSTEM TO INFLUENCE THE GREAT LAKES ARRIVES THURSDAY...BEFORE QUICKLY LIFTING NORTHEAST INTO QUEBEC FRIDAY. THIS SYSTEM WILL GENERATE ANOTHER ROUND OF SNOW ACROSS NORTHERN MICHIGAN THURSDAY...WHILE ALSO USHERING IN MUCH COLDER CONDITIONS FRIDAY AND INTO THE WEEKEND. ACCUMULATING LAKE EFFECT SNOW CAN BE EXPECTED OVER THE WESTERN GREAT LAKES THIS WEEKEND. && .UPDATE... ISSUED AT 930 PM EST TUE FEB 12 2013 FLURRIES HAVE TEMPORARILY ENDED ACROSS NW LWR MICHIGAN LATE THIS EVENING THANKS TO BUILDING SUBSIDENCE AND SHALLOWING OF THE LOW LEVEL MOIST LAYER. LATEST IR SATELLITE DOES SHOW A LINE OF COOLER CLOUD TOPS OVER CENTRAL UPR MICHIGAN ASSOCIATED WITH A WEAK VORT LOBE AND A NARROW BAND OF MID LEVEL MOISTURE. EXPECT THESE FEATURES WILL LEND TO REDEVELOPMENT OF ADDITIONAL LAKE EFFECT FLURRIES OVERNIGHT FOR FAR NRN AND NW LWR MICHIGAN AS WELL AS PORTIONS OF ERN UPR MICHIGAN...STILL UNDER THE DIRECTION OF SW LOW LEVEL FLOW. TEMPS CONTINUE TO FALL THRU THE 20S...ON THEIR WAY TO THE UPPER TEENS AND LOWER 20S FOR OVERNIGHT LOWS. UPDATE ISSUED AT 645 PM EST TUE FEB 12 2013 LAKE EFFECT FLURRIES CONTINUE TO STREAM INTO FAR NRN AND NW LWR MICHIGAN THIS EVENING UNDER THE DIRECTION OF LOW LEVEL SW FLOW. LOW CLOUDS REMAIN TRAPPED BELOW THE SUBSIDENCE INVERSION... MAINTAINING OVC SKIES ACROSS OUR ENTIRE CWA EVEN AWAY FROM ANY LAKE INFLUENCES. VERY LITTLE WILL CHANGE THRU THE NIGHT AS LOW LEVEL MOISTURE/CLOUDS REMAINS STUCK BELOW THE INVERSION AND SW FLOW CONTINUES TO PRODUCE FLURRIES FOR FAR NRN AND NW LWR MICHIGAN. OVERNIGHT LOWS IN THE UPPER TEENS TO LOWER 20S LOOKS REASONABLE GIVEN CURRENT SURFACE DWPTS IN THAT VCNTY. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 415 PM EST TUE FEB 12 2013 COLD AIR ADVECTION HAS ABOUT MAXED OUT BEHIND YESTERDAY`S DEPARTING STORM...WITH LATEST HIGH RES RUC ANALYSIS PLACING CIRCA -11C H85 TEMPERATURES ACROSS THE NORTH WOODS. DESPITE EXCEEDINGLY LOW INVERSIONS (H85 PER SAME RUC ANALYSIS)...MOISTURE DEPTH EXTENDING TO THE LOW END OF THE FAVORED DGZ CONTINUES TO KICK OFF WIDESPREAD FLURRIES IN FAVORED WEST FLOW LAKE AREAS. ABUNDANT LOW LEVEL MOISTURE ALSO LEADING TO A MAINLY CLOUDY DAY...WITH ANY SUBSTANTIAL CLEARING OF NOTE BACK ACROSS WISCONSIN. THIS CLEARING APPEARS TIED TO DOWNWARD FORCING ON BACKSIDE OF RATHER COMPACT SHORTWAVE PINWHEELING EAST INTO NORTHERN LAKE MICHIGAN. NO SIGNIFICANT CONCERNS THROUGH THE SHORT TERM (WEDNESDAY)...ALTHOUGH LINGERING FLURRIES AND CLOUD TRENDS WILL NEED ADDRESSING. WISCONSIN SHORTWAVE WILL STEADILY AND RAPIDLY PUSH ACROSS THE AREA THIS EVENING...AND LACK OF ANY APPRECIABLE MOISTURE SHOULD PRECLUDE MUCH...IF ANY...LAKE OR SYNOPTIC RESPONSE. H85 TEMPERATURES SLOWLY WARM IN DEVELOPING WEAK SOUTHWEST FLOW WAA REGIME...REACHING THE NEGATIVE SINGLE DIGITS BY MORNING. NAM-WRF BUFFER SOUNDINGS SHOW LOW LEVEL MOISTURE FALLING BELOW -10C ISOTHERM...WHICH COMBINED WITH LOWERING DELTA T/S...WOULD SUPPORT A QUICK DEMISE TO ONGOING FLURRIES. NOT WILLING TO BITE ON THIS JUST YET...AND PREFER TO KEEP FLURRIES IN THE FORECAST...SIMPLY FOLLOWING THE WINDS FOR THERE PLACEMENT (WHICH SUGGESTS THEY SHOULD CONFINE THEMSELVES IN FAVORED SOUTHWEST FLOW AREAS THROUGH THE NIGHT). CLOUD COVER REMAINS A FORMIDABLE CHALLENGE...ESPECIALLY GIVEN WHAT IS OCCURRING BEHIND UPSTREAM WAVE. DO HAVE SOME TREPIDATION GOING TOO AGGRESSIVE WITH CLOUDS OVERNIGHT...ESPECIALLY IN NON-FAVORED LAKE AREAS. SUBTLE WARM ADVECTION AND POST-WAVE DOWNWARD RESPONSE JUST MAY WORK IN TANDEM TO FORCE MUCH MORE CLEARING THAN THIS FORECAST WILL SUGGEST. WILL TREND PARTLY CLOUDY ACROSS EASTERN UPPER AND NORTHEAST LOWER AS A STARTING POINT...WITH KNOWLEDGE THAT COMPLETELY CLOUDY OR CLEAR IS THE MORE LIKELY OUTCOME. TEMPERATURES...OF COURSE...HIGHLY DEPENDENT ON HOW THIS WHOLE CLOUD THING UNFOLDS. MID AND UPPER TEENS MAY BE SEVERAL DEGREES TOO "WARM". WE SHALL SEE. SAME STORY HEADING INTO WEDNESDAY...WITH SOME LINGERING FLURRIES AND MOSTLY TO PARTLY CLOUDY SKIES. LOW LEVEL MODIFICATION CONTINUES...SUGGESTING HIGHS IN THE LOWER AND MIDDLE 30S. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 415 PM EST TUE FEB 12 2013 MAIN FORECAST CONCERNS WILL BE POTENTIAL FOR ACCUMULATING LAKE ENHANCED SNOWS STARTING THURSDAY AND CONTINUING INTO THE WEEKEND. THE LATEST HEMISPHERIC ANALYSIS SHOWS A STABLE 3-WAVE PATTERN WITH LARGE SCALE TROUGHING OVER CENTERED OVER JAMES BAY...EAST ASIA /AROUND 120E/ AND CENTRAL EUROPE. A VERY STRONG ZONAL JET REMAINS OVER EAST ASIA AND THE WESTERN PACIFIC...WITH A SLIT FLOW OVER THE EASTERN PACIFIC EXTENDING INTO THE WEST COAST. THE SPLIT FLOW MERGES TO FORM A FASTER JET THE SOUTHEASTERN U.S. THURSDAY...AN AMPLIFYING PATTERN IS EXPECTED WITH STRONG PACIFIC JET TO BEEF UP THE WEST COAST RIDGE...RESULTING IN INCREASED TROUGHING OVER THE EASTERN TWO THIRDS OF THE CONUS BY THURSDAY. SHORT WAVE ENERGY IS EXPECTED TO ROUND THE TOP OF THE RIDGE ON WEDNESDAY...BEFORE DIVING INTO THE GREAT LAKES BY THURSDAY. AN ASSOCIATED SURFACE RESPONSE/CLIPPER SYSTEM WILL MOVE THOUGH THE GREAT LAKES...BRINGING NORTHERN MICHIGAN THE NEXT CHANCE OF SOME LIGHT SNOW. THE AMOUNT OF MOISTURE THIS SYSTEM HAS TO WORK WITH IS NOT TERRIBLE...WITH MODEL SOUNDINGS SHOWING P-WATS OF AROUND 0.3 TO 0.4 INCHES ACROSS THE CWA. THE DEGREE OF FORCING REMAINS IN SOME QUESTION...WITH TWO DISTINCT AREAS OF ENHANCED PVA EXPECTED TO MOVE THROUGH THE REGION EMBEDDED IN THE SHEARED PIECE OF ENERGY. THE NAM/GFS WANT TO SPIN UP A STRONGER LOW WITH THIS FEATURE...WHILE THE ECMWF/GEM KEEP THE SURFACE LOW MORE BENIGN. PREFER THE LATTER OF THE SOLUTIONS...GIVEN THAT THESE TWO PIECES OF ENERGY DO NOT NECESSARILY PHASE TOGETHER. OVERALL LOOKING LIKE A 1 TO 2..PERHAPS LOCALLY 3 INCH SNOW EVENT. RAPIDLY CHANGING FLOW AND WARMISH AIR ALOFT WITH H85 TEMPS BETWEEN -5 TO -8C LOOK TO KEEP A MAJOR DAMPER OF ANY LAKE ENHANCEMENT. SNOW MAY BE ALSO BE SLOW TO ACCUMULATE ON ROAD SURFACES WITH SURFACE TEMPS AT OR SLIGHTLY ABOVE FREEZING...WITH THE MORE AGGRESSIVE NAM/GFS SUGGESTING HIGHS IN THE MID TO UPPER 30S FOR THURSDAY. THIS WOULD HAVE RAIN/SNOW MIX IMPLICATIONS FOR THE LOWER ELEVATIONS OF THE CWA...BUT PREFER THE MORE COOLER...LESS AMPLIFIED SOLUTIONS FOR NOW. THURSDAY NIGHT AND FRIDAY...FORCING BEGINS TO PUSH EAST OF THE AREA BY LATE THURSDAY AFTERNOON WITH STRONG COLD AIR ADVECTION ENSUING ACROSS THE CWA THURSDAY NIGHT INTO FRIDAY. THIS WILL RAMP UP THE LAKE EFFECT SNOW MACHINE DURING THIS TIMEFRAME. MODELS ARE NOT IN THE BEST AGREEMENT WITH THE NAM/GFS MORE NORTHWESTERLY THAN THE NNW FLOW DEPICTED BY THE ECMWF. MODEST INVERSION HEIGHTS AND DEEPEST MOISTURE MOVING OUT SHOULD KEEP MAJOR LAKE SNOW ACCUMULATIONS IN CHECK...HOWEVER SEVERAL INCHES OF ACCUMULATION LOOK LIKELY FOR THE NW/NNW FAVORED SNOW BELTS THROUGH FRIDAY. H85 TEMPS FALL TO -15 TO -18C DURING THE DAY FRIDAY...WITH MODEL CONSENSUS SHOWING HIGHS STRUGGLING TO MAKE IT OUT OF THE TEENS. FRIDAY NIGHT THROUGH TUESDAY...CHILLY CONDITIONS ENSUE AS DEEP TROUGH SETTLES INTO THE GREAT LAKES WITH MODEL CONSENSUS SHOWING H85 TEMPS IN THE -18 TO -22 RANGE ACROSS THE GREAT LAKES INTO THE DAY ON SATURDAY. CERTAINLY PLENTY OF INSTABILITY TO KEEP THE LAKE EFFECT SNOW MACHINE GOING...WITH POCKETS OF DEEPER H85-H7 MOISTURE ASSOCIATED WITH EMBEDDED SHORTWAVES ROUNDING THE LONGER WAVE TROUGH AND CONTINUED NORTHWEST TO NORTH NORTHWEST FLOW. AT THE LEAST...SEVERAL INCHES OF ACCUMULATION LOOK LIKELY IN THE NW TO NNW FAVORED SNOW BELTS WITH THIS PATTERN. LOOKING AT SOME OF COOP SNOWFALL GUIDANCE FROM THE CIPS ANALOGS FOR THE 72 HOUR PERIOD CENTERED ON 00Z/17 SHOWS HEAVY ACCUMULATIONS FOR 3 OF THE TO 5 ANALOGS. STILL PLENTY OF DETAILS TO WORK OUT BETWEEN NOW AND THIS WEEKEND...WITH ICE COVER OVER NORTHERN LAKE MICHIGAN AND MODEST INVERSION HEIGHTS SERVING AS MITIGATING FACTORS FOR HEAVY ACCUMULATIONS. STILL COULD SEE THE POSSIBILITY OF SOME HEADLINES FOR THE FRI/SAT TIMEFRAME...AND WILL MAINTAIN THE THREAT FOR ACCUMULATING LAKE SNOWS IN THE HWO. SUNDAY THROUGH MONDAY...PROGRESSIVE PATTERN CONTINUES WITH DEEP TROUGH KICKING OFF TO THE NORTHEAST AND HEIGHTS MODIFYING SUBSTANTIALLY AS UPSTREAM RIDGING BUILDS INTO THE GREAT LAKES. 1000-850 MEAN FLOW IS PROGGED TO BACK TO THE SOUTHWEST WITH H85 TEMPS MODIFYING ENOUGH TO END THE LES THREAT...ALTHOUGH THERE MAY BE SOME LINGER -SHSN FOR SW FAVORED FLOW AREAS INITIALLY SUNDAY MORNING. ANOTHER CLIPPER SYSTEM LOOKS TO TRAVERSE THE AREA SUNDAY NIGHT INTO MONDAY...HOWEVER THE BETTER MOISTURE AND FORCING LOOK TO REMAIN OVER THE NORTHERN PORTION OF THE CWA ATTM. MONDAY NIGHT INTO TUESDAY...NEXT TROUGH BUILDS INTO THE GREAT LAKES WITH GFS/ECMWF DEPICTING A STORM SYSTEM DEVELOPING IN THE SOUTHERN PLAINS AND MOVING UP THROUGH THE OHIO VALLEY INTO THE GREAT LAKES. NOT A LOT OF CONFIDENCE OF COURSE THIS FAR OUT...ESPECIALLY WHEN LOOKING AT SOME OF THE ENSEMBLE GUIDANCE ON THE UPPER AIR PATTERN...BUT SOME SIGNALS ARE THERE OF SAID SYSTEM WHEN LOOKING AT THE REANALYSIS BASED ON THE TOP GFS/CAN ENS TOP ANALOGS. SOMETHING THAT WILL CERTAINLY NEED TO BE MONITORED. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 645 PM EST TUE FEB 12 2013 MVFR CIGS WILL HOLD OVER ALL NRN LWR MICHIGAN TAF SITES THRU WEDNESDAY EVENING AS SHALLOW LOW LEVEL MOISTURE REMAINS TRAPPED BELOW THE SUBSIDENCE INVERSION. VSBYS WILL REMAIN VFR DESPITE SOME SW FLOW LAKE EFFECT FLURRIES STREAMING INTO PORTIONS OF FAR NRN AND NW LWR MICHIGAN. SW WINDS WILL REMAIN AOB 10 KTS THRU THE FORECAST PERIOD. && .MARINE... ISSUED AT 415 PM EST TUE FEB 12 2013 MARINE...VEERING WINDS TO SOUTHWEST REMAIN SOMEWHAT GUSTY HEADING INTO THIS EVENING. MAY EVEN SEE SOME SCA PRODUCING GUSTS ALONG THE NORTHWEST LOWER LAKE MICHIGAN COAST...ALTHOUGH DURATION DOES NOT SUPPORT A SPECIFIC SCA HEADLINE. SOUTHWEST AND SUB-ADVISORY WINDS TO CONTINUE THROUGH THURSDAY MORNING. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...MR SYNOPSIS...SR SHORT TERM...MB LONG TERM...NS AVIATION...MR MARINE...MB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
645 PM EST TUE FEB 12 2013 .SYNOPSIS... ISSUED AT 415 PM EST TUE FEB 12 2013 WEAK HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT LAKES TONIGHT AND WEDNESDAY. THIS PATTERN WILL GENERATE ABOVE NORMAL TEMPERATURES AND OCCASIONAL FLURRIES...ACROSS THE NORTHERN MICHIGAN INTO THURSDAY. HOWEVER...THE NEXT SYSTEM TO INFLUENCE THE GREAT LAKES ARRIVES THURSDAY...BEFORE QUICKLY LIFTING NORTHEAST INTO QUEBEC FRIDAY. THIS SYSTEM WILL GENERATE ANOTHER ROUND OF SNOW ACROSS NORTHERN MICHIGAN THURSDAY...WHILE ALSO USHERING IN MUCH COLDER CONDITIONS FRIDAY AND INTO THE WEEKEND. ACCUMULATING LAKE EFFECT SNOW CAN BE EXPECTED OVER THE WESTERN GREAT LAKES THIS WEEKEND. && .UPDATE... ISSUED AT 645 PM EST TUE FEB 12 2013 LAKE EFFECT FLURRIES CONTINUE TO STREAM INTO FAR NRN AND NW LWR MICHIGAN THIS EVENING UNDER THE DIRECTION OF LOW LEVEL SW FLOW. LOW CLOUDS REMAIN TRAPPED BELOW THE SUBSIDENCE INVERSION... MAINTAINING OVC SKIES ACROSS OUR ENTIRE CWA EVEN AWAY FROM ANY LAKE INFLUENCES. VERY LITTLE WILL CHANGE THRU THE NIGHT AS LOW LEVEL MOISTURE/CLOUDS REMAINS STUCK BELOW THE INVERSION AND SW FLOW CONTINUES TO PRODUCE FLURRIES FOR FAR NRN AND NW LWR MICHIGAN. OVERNIGHT LOWS IN THE UPPER TEENS TO LOWER 20S LOOKS REASONABLE GIVEN CURRENT SURFACE DWPTS IN THAT VCNTY. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 415 PM EST TUE FEB 12 2013 COLD AIR ADVECTION HAS ABOUT MAXED OUT BEHIND YESTERDAY`S DEPARTING STORM...WITH LATEST HIGH RES RUC ANALYSIS PLACING CIRCA -11C H85 TEMPERATURES ACROSS THE NORTH WOODS. DESPITE EXCEEDINGLY LOW INVERSIONS (H85 PER SAME RUC ANALYSIS)...MOISTURE DEPTH EXTENDING TO THE LOW END OF THE FAVORED DGZ CONTINUES TO KICK OFF WIDESPREAD FLURRIES IN FAVORED WEST FLOW LAKE AREAS. ABUNDANT LOW LEVEL MOISTURE ALSO LEADING TO A MAINLY CLOUDY DAY...WITH ANY SUBSTANTIAL CLEARING OF NOTE BACK ACROSS WISCONSIN. THIS CLEARING APPEARS TIED TO DOWNWARD FORCING ON BACKSIDE OF RATHER COMPACT SHORTWAVE PINWHEELING EAST INTO NORTHERN LAKE MICHIGAN. NO SIGNIFICANT CONCERNS THROUGH THE SHORT TERM (WEDNESDAY)...ALTHOUGH LINGERING FLURRIES AND CLOUD TRENDS WILL NEED ADDRESSING. WISCONSIN SHORTWAVE WILL STEADILY AND RAPIDLY PUSH ACROSS THE AREA THIS EVENING...AND LACK OF ANY APPRECIABLE MOISTURE SHOULD PRECLUDE MUCH...IF ANY...LAKE OR SYNOPTIC RESPONSE. H85 TEMPERATURES SLOWLY WARM IN DEVELOPING WEAK SOUTHWEST FLOW WAA REGIME...REACHING THE NEGATIVE SINGLE DIGITS BY MORNING. NAM-WRF BUFFER SOUNDINGS SHOW LOW LEVEL MOISTURE FALLING BELOW -10C ISOTHERM...WHICH COMBINED WITH LOWERING DELTA T/S...WOULD SUPPORT A QUICK DEMISE TO ONGOING FLURRIES. NOT WILLING TO BITE ON THIS JUST YET...AND PREFER TO KEEP FLURRIES IN THE FORECAST...SIMPLY FOLLOWING THE WINDS FOR THERE PLACEMENT (WHICH SUGGESTS THEY SHOULD CONFINE THEMSELVES IN FAVORED SOUTHWEST FLOW AREAS THROUGH THE NIGHT). CLOUD COVER REMAINS A FORMIDABLE CHALLENGE...ESPECIALLY GIVEN WHAT IS OCCURRING BEHIND UPSTREAM WAVE. DO HAVE SOME TREPIDATION GOING TOO AGGRESSIVE WITH CLOUDS OVERNIGHT...ESPECIALLY IN NON-FAVORED LAKE AREAS. SUBTLE WARM ADVECTION AND POST-WAVE DOWNWARD RESPONSE JUST MAY WORK IN TANDEM TO FORCE MUCH MORE CLEARING THAN THIS FORECAST WILL SUGGEST. WILL TREND PARTLY CLOUDY ACROSS EASTERN UPPER AND NORTHEAST LOWER AS A STARTING POINT...WITH KNOWLEDGE THAT COMPLETELY CLOUDY OR CLEAR IS THE MORE LIKELY OUTCOME. TEMPERATURES...OF COURSE...HIGHLY DEPENDENT ON HOW THIS WHOLE CLOUD THING UNFOLDS. MID AND UPPER TEENS MAY BE SEVERAL DEGREES TOO "WARM". WE SHALL SEE. SAME STORY HEADING INTO WEDNESDAY...WITH SOME LINGERING FLURRIES AND MOSTLY TO PARTLY CLOUDY SKIES. LOW LEVEL MODIFICATION CONTINUES...SUGGESTING HIGHS IN THE LOWER AND MIDDLE 30S. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 415 PM EST TUE FEB 12 2013 MAIN FORECAST CONCERNS WILL BE POTENTIAL FOR ACCUMULATING LAKE ENHANCED SNOWS STARTING THURSDAY AND CONTINUING INTO THE WEEKEND. THE LATEST HEMISPHERIC ANALYSIS SHOWS A STABLE 3-WAVE PATTERN WITH LARGE SCALE TROUGHING OVER CENTERED OVER JAMES BAY...EAST ASIA /AROUND 120E/ AND CENTRAL EUROPE. A VERY STRONG ZONAL JET REMAINS OVER EAST ASIA AND THE WESTERN PACIFIC...WITH A SLIT FLOW OVER THE EASTERN PACIFIC EXTENDING INTO THE WEST COAST. THE SPLIT FLOW MERGES TO FORM A FASTER JET THE SOUTHEASTERN U.S. THURSDAY...AN AMPLIFYING PATTERN IS EXPECTED WITH STRONG PACIFIC JET TO BEEF UP THE WEST COAST RIDGE...RESULTING IN INCREASED TROUGHING OVER THE EASTERN TWO THIRDS OF THE CONUS BY THURSDAY. SHORT WAVE ENERGY IS EXPECTED TO ROUND THE TOP OF THE RIDGE ON WEDNESDAY...BEFORE DIVING INTO THE GREAT LAKES BY THURSDAY. AN ASSOCIATED SURFACE RESPONSE/CLIPPER SYSTEM WILL MOVE THOUGH THE GREAT LAKES...BRINGING NORTHERN MICHIGAN THE NEXT CHANCE OF SOME LIGHT SNOW. THE AMOUNT OF MOISTURE THIS SYSTEM HAS TO WORK WITH IS NOT TERRIBLE...WITH MODEL SOUNDINGS SHOWING P-WATS OF AROUND 0.3 TO 0.4 INCHES ACROSS THE CWA. THE DEGREE OF FORCING REMAINS IN SOME QUESTION...WITH TWO DISTINCT AREAS OF ENHANCED PVA EXPECTED TO MOVE THROUGH THE REGION EMBEDDED IN THE SHEARED PIECE OF ENERGY. THE NAM/GFS WANT TO SPIN UP A STRONGER LOW WITH THIS FEATURE...WHILE THE ECMWF/GEM KEEP THE SURFACE LOW MORE BENIGN. PREFER THE LATTER OF THE SOLUTIONS...GIVEN THAT THESE TWO PIECES OF ENERGY DO NOT NECESSARILY PHASE TOGETHER. OVERALL LOOKING LIKE A 1 TO 2..PERHAPS LOCALLY 3 INCH SNOW EVENT. RAPIDLY CHANGING FLOW AND WARMISH AIR ALOFT WITH H85 TEMPS BETWEEN -5 TO -8C LOOK TO KEEP A MAJOR DAMPER OF ANY LAKE ENHANCEMENT. SNOW MAY BE ALSO BE SLOW TO ACCUMULATE ON ROAD SURFACES WITH SURFACE TEMPS AT OR SLIGHTLY ABOVE FREEZING...WITH THE MORE AGGRESSIVE NAM/GFS SUGGESTING HIGHS IN THE MID TO UPPER 30S FOR THURSDAY. THIS WOULD HAVE RAIN/SNOW MIX IMPLICATIONS FOR THE LOWER ELEVATIONS OF THE CWA...BUT PREFER THE MORE COOLER...LESS AMPLIFIED SOLUTIONS FOR NOW. THURSDAY NIGHT AND FRIDAY...FORCING BEGINS TO PUSH EAST OF THE AREA BY LATE THURSDAY AFTERNOON WITH STRONG COLD AIR ADVECTION ENSUING ACROSS THE CWA THURSDAY NIGHT INTO FRIDAY. THIS WILL RAMP UP THE LAKE EFFECT SNOW MACHINE DURING THIS TIMEFRAME. MODELS ARE NOT IN THE BEST AGREEMENT WITH THE NAM/GFS MORE NORTHWESTERLY THAN THE NNW FLOW DEPICTED BY THE ECMWF. MODEST INVERSION HEIGHTS AND DEEPEST MOISTURE MOVING OUT SHOULD KEEP MAJOR LAKE SNOW ACCUMULATIONS IN CHECK...HOWEVER SEVERAL INCHES OF ACCUMULATION LOOK LIKELY FOR THE NW/NNW FAVORED SNOW BELTS THROUGH FRIDAY. H85 TEMPS FALL TO -15 TO -18C DURING THE DAY FRIDAY...WITH MODEL CONSENSUS SHOWING HIGHS STRUGGLING TO MAKE IT OUT OF THE TEENS. FRIDAY NIGHT THROUGH TUESDAY...CHILLY CONDITIONS ENSUE AS DEEP TROUGH SETTLES INTO THE GREAT LAKES WITH MODEL CONSENSUS SHOWING H85 TEMPS IN THE -18 TO -22 RANGE ACROSS THE GREAT LAKES INTO THE DAY ON SATURDAY. CERTAINLY PLENTY OF INSTABILITY TO KEEP THE LAKE EFFECT SNOW MACHINE GOING...WITH POCKETS OF DEEPER H85-H7 MOISTURE ASSOCIATED WITH EMBEDDED SHORTWAVES ROUNDING THE LONGER WAVE TROUGH AND CONTINUED NORTHWEST TO NORTH NORTHWEST FLOW. AT THE LEAST...SEVERAL INCHES OF ACCUMULATION LOOK LIKELY IN THE NW TO NNW FAVORED SNOW BELTS WITH THIS PATTERN. LOOKING AT SOME OF COOP SNOWFALL GUIDANCE FROM THE CIPS ANALOGS FOR THE 72 HOUR PERIOD CENTERED ON 00Z/17 SHOWS HEAVY ACCUMULATIONS FOR 3 OF THE TO 5 ANALOGS. STILL PLENTY OF DETAILS TO WORK OUT BETWEEN NOW AND THIS WEEKEND...WITH ICE COVER OVER NORTHERN LAKE MICHIGAN AND MODEST INVERSION HEIGHTS SERVING AS MITIGATING FACTORS FOR HEAVY ACCUMULATIONS. STILL COULD SEE THE POSSIBILITY OF SOME HEADLINES FOR THE FRI/SAT TIMEFRAME...AND WILL MAINTAIN THE THREAT FOR ACCUMULATING LAKE SNOWS IN THE HWO. SUNDAY THROUGH MONDAY...PROGRESSIVE PATTERN CONTINUES WITH DEEP TROUGH KICKING OFF TO THE NORTHEAST AND HEIGHTS MODIFYING SUBSTANTIALLY AS UPSTREAM RIDGING BUILDS INTO THE GREAT LAKES. 1000-850 MEAN FLOW IS PROGGED TO BACK TO THE SOUTHWEST WITH H85 TEMPS MODIFYING ENOUGH TO END THE LES THREAT...ALTHOUGH THERE MAY BE SOME LINGER -SHSN FOR SW FAVORED FLOW AREAS INITIALLY SUNDAY MORNING. ANOTHER CLIPPER SYSTEM LOOKS TO TRAVERSE THE AREA SUNDAY NIGHT INTO MONDAY...HOWEVER THE BETTER MOISTURE AND FORCING LOOK TO REMAIN OVER THE NORTHERN PORTION OF THE CWA ATTM. MONDAY NIGHT INTO TUESDAY...NEXT TROUGH BUILDS INTO THE GREAT LAKES WITH GFS/ECMWF DEPICTING A STORM SYSTEM DEVELOPING IN THE SOUTHERN PLAINS AND MOVING UP THROUGH THE OHIO VALLEY INTO THE GREAT LAKES. NOT A LOT OF CONFIDENCE OF COURSE THIS FAR OUT...ESPECIALLY WHEN LOOKING AT SOME OF THE ENSEMBLE GUIDANCE ON THE UPPER AIR PATTERN...BUT SOME SIGNALS ARE THERE OF SAID SYSTEM WHEN LOOKING AT THE REANALYSIS BASED ON THE TOP GFS/CAN ENS TOP ANALOGS. SOMETHING THAT WILL CERTAINLY NEED TO BE MONITORED. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 645 PM EST TUE FEB 12 2013 MVFR CIGS WILL HOLD OVER ALL NRN LWR MICHIGAN TAF SITES THRU WEDNESDAY EVENING AS SHALLOW LOW LEVEL MOISTURE REMAINS TRAPPED BELOW THE SUBSIDENCE INVERSION. VSBYS WILL REMAIN VFR DESPITE SOME SW FLOW LAKE EFFECT FLURRIES STREAMING INTO PORTIONS OF FAR NRN AND NW LWR MICHIGAN. SW WINDS WILL REMAIN AOB 10 KTS THRU THE FORECAST PERIOD. && .MARINE... ISSUED AT 415 PM EST TUE FEB 12 2013 MARINE...VEERING WINDS TO SOUTHWEST REMAIN SOMEWHAT GUSTY HEADING INTO THIS EVENING. MAY EVEN SEE SOME SCA PRODUCING GUSTS ALONG THE NORTHWEST LOWER LAKE MICHIGAN COAST...ALTHOUGH DURATION DOES NOT SUPPORT A SPECIFIC SCA HEADLINE. SOUTHWEST AND SUB-ADVISORY WINDS TO CONTINUE THROUGH THURSDAY MORNING. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...MR SYNOPSIS...SR SHORT TERM...MB LONG TERM...NS AVIATION...MR MARINE...MB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
407 PM EST MON FEB 11 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 406 PM EST MON FEB 11 2013 PER WATER VAPOR IMAGERY AND RUC ANALYSIS...BROAD MID LEVEL TROUGH AND ASSOC CLOSED LOW ARE PROGRESSING STEADILY EAST OF THE UPPER GREAT LAKES. IN RESPONSE TO INCREASED RDGG FROM THE WEST...MODELS INDICATE INCREASING Q-VECT DIV/SUBSIDENCE SPREADING WEST TO EAST ACROSS FCST AREA INTO THIS EVENING. COMBINATION OF MQT RADAR...VIS SATELLITE AND AREA WEB CAMS SUGGEST ONLY LIGHT SNOW OR FLURRIES ACROSS THE CWA. THERE IS A BETTER BAND OF LES OVER WRN LAKE SUPERIOR AFFECTING NW WI THIS AFTERNOON WITH LIGHT TO MODERATE SNOW PER DLH RADAR. GIVEN THAT DEEPER MOISTURE WILL EXIT EAST TONIGHT WITH FLOW BCMG INCREASINGLY ANTICYCLONIC...SNOW NEAR LAKE SUPERIOR SHOULD STEADILY DIMINISH W TO E (POSSIBLY EVEN END) AS 850MB TEMPS WILL BE MARGINAL AROUND THE THRESHOLD FOR LES. AS A RESULT OF CONTINUED DIMINISHING TREND TO LES...EXPECT TO CANCEL REMAINING WINTER WX ADVISORIES OVER WRN COUNTIES ON THE AFTERNOON FCST ISSUANCE. EVEN IF BAND OVER NW WI DOES SWING INTO FAR WRN UPR MI...BELIEVE ANY INCREASE IN LES WILL BE SHORT-LIVED AND NOT BE WORTHY OF ADVISORY HEADLINE. LINGERING LIGHT LAKE EFFECT IS EXPECTED EAST TUE MORNING...BUT INCREASED DRYING/RDGG FROM WEST TO EAST...WARMING 850MB TEMPS AND WINDS BACKING TO THE SOUTHWEST WITH THE SURFACE RIDGE MOVING ACROSS THE REGION SHOULD QUICKLY DIMINISH OR END LAKE EFFECT SNOW DURING THE DAY TUESDAY. EXPECT CLOUDS TO GENERALLY DIMINISH AS WELL THROUGH THE DAY WITH INCREASED RDGG. GENERALLY FOLLOWED A BLEND OF CONSENSUS MODEL GUIDANCE FOR LOW TEMPS TONIGHT AND HIGH TEMPS ON TUESDAY. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 406 PM EST MON FEB 11 2013 EXPECT NW FLOW ALOFT THROUGH MUCH OF THE LONG TERM PERIOD...WITH SEVERAL OPEN WAVES DIVING TOWARD THE UPPER GREAT LAKES. LAKE EFFECT SNOW SHOWERS OVER THE KEWEENAW PENINSULA...AND NEAR AND EAST OF MUNISING NEAR LAKE SUPERIOR WILL BE COMMON. THE NEXT SYSTEM TO INFLUENCE OUR WEATHER WILL BE IN THE FORM OF A SFC TROUGH EXTENDING FROM THE PARENT LOW OVER HUDSON BAY. THE TROUGH WILL SWEEP W-E ACROSS UPPER MI TUESDAY NIGHT...BEFORE EXITING TO EASTERN ONTARIO LATE WEDNESDAY MORNING. 850MB TEMPS OF -7 TO -10C. YET ANOTHER QUICK CLIPPER SYSTEM SET UP OVER CENTRAL ALBERTA AND SASKATCHEWAN TUESDAY NIGHT WILL QUICKLY CROSS LAKE WINNIPEG WEDNESDAY MORNING...AND PUSH INTO WESTERN LAKE SUPERIOR WEDNESDAY EVENING...THEN ACROSS CENTRAL UPPER MI/LAKE SUPERIOR BY 12Z THURSDAY...AND EASTERN UPPER MI AROUND 18Z. WHILE THE NAM/GFS/ECMWF/SREF SHOW A SIMILAR TRACK TO THE SFC LOW...THE 11/00Z CANADIAN IS APPROX 300MI SW OF THE CONSENSUS. WILL LIMIT THE USE OF THE 11/00Z CANADIAN FORECAST FOR WEDNESDAY THROUGH THURSDAY. SNOW AMOUNTS WEDNESDAY NIGHT THROUGH THURSDAY COULD ACCUMULATE 3 TO 6 INCHES OF LES FROM IWD UP THROUGH THE KEWEENAW PENINSULA...WITH SNOW TO LIQUID RATIOS AROUND 17:1. LIGHTER AMOUNTS OF 2 TO 5 INCHES WILL BE POSSIBLE NORTH CENTRAL...AND 1 TO 3 INCHES ELSEWHERE. WILL ADD THE MENTION OF LIGHT TO MODERATE SNOW WITH LAKE ENHANCEMENT FOR WEDNESDAY NIGHT THROUGH THURSDAY...BEFORE THE DGZ FALLS CLOSER TO THE SFC AS COLDER AIR PUSHES IN...LIMITING SIGNIFICANT ACCUMULATIONS. A WEAKENING SFC TROUGH WILL AGAIN LINGER ACROSS CENTRAL AND EASTERN LAKE SUPERIOR THURSDAY NIGHT THROUGH SATURDAY AS STRONGER HIGH PRESSURE SINKS ACROSS THE CENTRAL CANADA AND THE PLAINS STATES...WITH A RIDGE EDGING INTO WESTERN UPPER MI/LAKE SUPERIOR. THE 11/12Z GFS WAS A BIT STRONGER WITH WHAT THE ECMWF HAS AS AN OPEN WAVE PUSHING IN FROM THE NNW SATURDAY...ACCENTUATING THE SFC LOW OVER EASTERN LAKE SUPERIOR. EITHER WAY...LAKE EFFECT SNOW SHOWERS WILL BE LINGERING OVER CENTRAL AND EASTERN UPPER MI NEAR LAKE SUPERIOR. EXPECT LES TO PICK UP SIGNIFICANTLY THURSDAY AFTERNOON AND EVENING AS COLDER AIR FILTERS IN BEHIND THE EXITING LOW ON FAVORABLE NNW WINDS. 850MB TEMPS WILL FALL TO AROUND -17C OVER THE W HALF BY THE END OF THE DAY THURSDAY...WITH FURTHER COOLING TO -19 TO -20C THROUGH THE START OF THE WEEKEND. -22 TO -24C LOOKS TO BE THE COOLEST POINT...SATURDAY AFTERNOON. WHILE THE 11/06Z GFS AND 11/00Z ECMWF ARE PRETTY CONSISTENT UNTIL SATURDAY...THEY BEGIN TO DIVERGE SATURDAY AFTERNOON...WITH THE GFS DEVELOPING A LOW OVER THE CENTRAL PLAINS BECOMING OUT OF PHASE WITH THE REST OF THE AVAILABLE MODELS. THE GOOD NEWS IS THAT THE 11/12Z GFS LOOKS TO HAVE FIXED THIS POTENTIAL PROBLEM...AND ANOTHER POSSIBLE STORM TOWARD THE EAST COAST FOR THE UPCOMING WEEKEND. EXPECT A COOL RIDGE OF HIGH PRESSURE TO EDGE ACROSS THE UPPER GREAT LAKES FOR THE WEEKEND...AS AN ELONGATED TROUGH GAINS STEAM FROM CENTRAL CANADA THROUGH THE CENTRAL PLAINS STATES ON SUNDAY. FOR MONDAY IT WILL BE A QUESTION AS TO IF THE SOUTHERN OR NORTHERN STREAM WINS OUT. AT THIS POINT THE 11/00Z ECMWF LOOKS TO BE STRONGER WITH THE SYSTEM AS A WHOLE...BUT WILL WAIT UNTIL THE TIME PERIOD BECOMES A BIT MORE CLEAR BEFORE LEANING TO ONE SOLUTION OVER ANOTHER. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 125 PM EST MON FEB 11 2013 IFR CONDITIONS WITH LAKE ENHANCED -SN SHOULD PREVAIL AT KIWD/KCMX/KSAW THIS AFTERNOON UNDER GUSTY NNW WINDS ON BACKSIDE OF LOW PRES SYSTEM MOVING EAST OF LAKE SUPEPIOR. MID TO LATE AFTERNOON...IMPROVEMENT INTO THE MVFR RANGE IS EXPECTED AS THE STORM SYSTEM CONTINUES TO MOVE EAST. MVFR CIGS MAY SCATTER OUT LATE TONIGHT AT KIWD AS WINDS BACK TOWARD THE SW...AND PERHAPS AT KSAW UNDER DOWNSLOPING W TO NW WINDS. LOOK FOR MVFR CIGS TO SCT OUT AT BOTH KCMX AND KSAW BY LATE TUE MORNING WITH INCREASED SUBSIDENCE AND RDGG. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 406 PM EST MON FEB 11 2013 NW GALES OVER CENTRAL LAKE SUPERIOR AIDED BY PRES RISE MAX WILL DIMINISH BLO GALES BY LATE EVENING AS NW GRADIENT WEAKENS DUE TO LOW DEPARTING EAST AND RDG BUILDING IN FM WEST. HIGH PRES RDG AXIS MOVG EAST ACROSS THE LAKE WILL KEEP WINDS AOB 20 KTS OVER EAST HALF OF LAKE SUPERIOR. WEST HALF AND FAR NCNTRL LAKE SHOULD SEE AN INCREASE IN SW WINDS TUE AFTERNOON TO 25 KTS WITH TIGHTENING GRAD ON BACKSIDE OF RDG AXIS. A WEAK TROUGH STRETCHING FROM HUDSON BAY THROUGH THE UPPER GREAT LAKES TUESDAY NIGHT WILL BE REINFORCED BY ANOTHER LOW FROM THE NORTHWEST...THAT WILL PUSH ACROSS LAKE SUPERIOR/UPPER MI THURSDAY MORNING INTO THURSDAY AFTERNOON...BEFORE QUICKLY EXITING INTO SOUTERN ONTARIO AND QUEBEC THURSDAY AFTERNOON/EVENING. A FEW N GALE FORCE GUSTS TO 35KTS WILL BE POSSIBLE THURSDAY AFTERNOON ACROSS MAINLY CENTRAL LAKE SUPERIOR...WITH HEAVY FREEZING SPRAY OVER MUCH OF THE LAKE THURSDAY NIGHT. WHILE A WEAKENING TROUGH OF LOW PRESSURE REMAINS OVER EASTERN LAKE SUPERIOR...HIGH PRESSURE WILL SLOWLY BUILD IN FROM THE WEST THORUGH SATURDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LSZ248>250-265-266. GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ264. LAKE MICHIGAN... NONE. && $$ SHORT TERM...VOSS LONG TERM...KF AVIATION...VOSS MARINE...VOSS/KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
138 PM EST MON FEB 11 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 525 AM EST MON FEB 11 2013 PER WATER VAPOR IMAGERY AND RUC ANALYSIS...MID LEVEL LOW IS CURRENTLY SPINNING EASTWARD OVER NRN WI ATTM. ASSOCIATED SFC LOW APPEARS TO BE NEARING THE AREA BTWN WATERSMEET AND IRON RIVER. WHILE MAIN BAND OF WAA/ISENTROPIC ASCENT PCPN HAS PUSHED WELL N AND E OF THE AREA...REGIONAL RADAR IMAGERY SHOWS AREAS OF MOSTLY LIGHT PCPN CIRCULATING AROUND THE MID LEVEL LOW. AHEAD OF THE LOW...LOW-LEVELS HAVE WARMED SUFFICIENTLY OVER ROUGHLY THE E HALF OF UPPER MI TO RESULT IN PTYPE BEING JUST RAIN EARLY THIS MORNING (SFC TEMPS HAVE EVEN RISEN TO THE MID/UPPER 30S). PCPN TRANSITIONS BACK TO SNOW OVER WRN UPPER MI AND NW WI. OVER THE NEXT SEVERAL HRS...COLUMN WILL COOL AS MID LEVEL LOW TRACKS EASTWARD. AS A RESULT...WHERE PCPN IS NOW RAIN...IT WILL CHANGE BACK TO ALL SNOW DURING THE MORNING. ATTENTION THEN TURNS TO POTENTIAL LAKE ENHANCEMENT TODAY. IT WON`T BE THE TYPICAL LAKE ENHANCED EVENT PRODUCING MDT/HVY SNOW THAT WOULD NORMALLY BE EXPECTED AT THIS TIME OF YEAR BECAUSE THE AIR MASS IS MILD ACROSS THE AREA RIGHT NOW (850MB TEMPS ARE -1 TO -5C OVER LAKE SUPERIOR). SO INITIALLY...EVEN AS WINDS INCREASE OUT OF THE N TO NW BEHIND SFC LOW...AIR MASS WILL BE TOO WARM FOR LAKE ENHANCEMENT THOUGH THERE WILL BE SOME TERRAIN ENHANCEMENT FROM THE UPSLOPING FLOW. OVER THE W...THERE WILL BE A WINDOW FOR LAKE ENHANCEMENT FROM LATE MORNING INTO THE AFTN AS 850MB TEMPS FALL BLO -7C. INTO NCNTRL UPPER MI...WINDOW LOOKS SHORTER LATE THIS AFTN/EVENING. THUS...PROBABLY SHOULDN`T SEE MUCH MORE THAN 2-4 INCHES OF SNOW OVER THE W TODAY. BEHIND THE SFC LOW...WINDS MORE QUICKLY BACK NW ACROSS NCNTRL UPPER MI WHICH WILL LIMIT LAKE ENHANCEMENT AND MORE QUICKLY DIMINISH TERRAIN ENHANCEMENT INTO MARQUETTE COUNTY. CONSIDERED DROPPING ADVY FOR MARQUETTE COUNTY... BUT WILL WAIT TO SEE HOW THINGS EVOLVE DURING THE MORNING OVER THE W TO GET AN IDEA OF HOW ENHANCEMENT WILL PLAY OUT OVER THE NCNTRL. IT`S POSSIBLE AN ADVY MAY BE NEEDED TO THE E OF MARQUETTE LATER THIS AFTN/EVENING...BUT EXPECTATION IS THAT SNOW ACCUMULATIONS WILL BE UNDER ADVY AMOUNTS. PERIOD OF GUSTY N/NW WINDS TO 30-35MPH ALONG LAKE SUPERIOR NW AND NCNTRL WILL LEAD TO SOME BLSN THIS AFTN/EVENING. AS FOR HEADLINES...CANCELLED ADVY FOR MENOMINEE/DELTA/ALGER EASTWARD AS TEMPS HAVE RISEN TO THE MID/UPPER 30S WITH ONLY RAIN FALLING. REMAINING ADVYS WERE NOT CHANGED. AS DEEPER MOISTURE EXITS TONIGHT...SNOW NEAR LAKE SUPERIOR SHOULD STEADILY DIMINISH W TO E (POSSIBLY EVEN END) AS 850MB TEMPS WILL BE MARGINAL AROUND THE THRESHOLD FOR LES. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 424 AM EST MON FEB 11 2013 LINGERING LIGHT LAKE EFFECT IS EXPECTED FOR THE START OF THE LONG TERM PERIOD. BUT INCREASED DRYING FROM WEST TO EAST...WARMING 850MB TEMPS AND WINDS BACKING TO THE SOUTHWEST WITH THE SURFACE RIDGE MOVING ACROSS THE REGION ON TUESDAY WILL LEAD QUICKLY DIMINISHING LAKE EFFECT SNOW DURING THE DAY TUESDAY. CLOUDS WILL ALSO BE ON THE DECREASE THROUGH THE DAY AND GOING FORECAST HAS A DECENT TREND ON THAT IDEA. THE HIGH PRESSURE RIDGE QUICKLY SLIDES EAST ON TUESDAY AFTERNOON/EVENING AND AREA COMES UNDER THE INFLUENCE OF SEVERAL NORTHERN STREAM WAVES FOR THE REST OF THE WORK WEEK. THE FIRST WAVE...NEAR LAKE WINNIPEG AT 00Z WED...WILL DIVE SOUTHEAST ACROSS LAKE SUPERIOR ON WEDNESDAY. BEST DEEP MOISTURE LOOKS TO STAY OVER THE NORTHEAST HALF OF THE LAKE AND WITH GENERALLY WESTERLY FLOW ACROSS THE CWA...DON/T EXPECT MUCH FOR PRECIPITATION CHANCES ON WEDNESDAY EVEN THOUGH THE BROAD SURFACE TROUGH MOVES THROUGH. THE NEXT SHORTWAVE...TRACKING FARTHER TO THE SOUTHEAST...WILL DEPART ALBERTA ON WEDNESDAY AND MOVE INTO THE NORTHERN PLAINS ON WEDNESDAY EVENING AND THEN TRACK INTO THE WESTERN GREAT LAKES FOR THURSDAY. STILL SOME DIFFERENCES IN THE DETERMINISTIC MODELS AND ENSEMBLE MEMBERS FROM THE GFS/GEM/ECMWF WITH THE STRENGTH OF THIS SHORTWAVE AND THE RESULTING STRENGTH/LOCATION OF THE ASSOCIATED SURFACE LOW. HPC PREFERS A BLEND OF THE 18Z GFES AND 12Z ECMWF ENS MEAN AND THAT SEEMS LIKE A DECENT COMPROMISE. THIS WOULD SWEEP THE SHORTWAVE THROUGH WISCONSIN ON THURSDAY AND HAVE A LOW 1000S MB LOW MOVING THROUGH NORTHERN WISCONSIN OR SOUTHERN UPPER MICHIGAN. AT THIS POINT...WOULD JUST EXPECT A DUSTING TO A COUPLE INCHES OF SNOW WITH THIS SYSTEM...UNLESS THE STRONGER GFS SOLUTION IS CORRECT WHICH WOULD PRODUCE ADVISORY SNOWFALL. ANOTHER SHORTWAVE DIVING SSE ON THE BACK SIDE OF THE THURSDAY SHORTWAVE WILL AMPLIFY THE UPPER TROUGH FURTHER AND LEAD TO IT MERGING WITH THE SOUTHERN STREAM FOR FRIDAY AND THE WEEKEND...WHILE AN UPPER RIDGE BUILDS OVER THE WRN CONUS. THIS WILL ALLOW COLDER AIR TO SPILL SOUTH ACROSS THE UPPER GREAT LAKES REGION AND PRODUCE A PERIOD OF BELOW NORMAL TEMPERATURES THROUGH THE WEEKEND. WITH THIS COLDER AIR...ALSO EXPECT THE AREA TO SEE LAKE EFFECT SNOW DUE TO 850MB TEMPS FALLING TOWARDS -21C BY SATURDAY. WITH A HIGH PRESSURE RIDGE EXPECTED TO BUILD INTO THE NORTHERN PLAINS DURING THIS TIME...WIND DIRECTIONS WILL DEPEND ON IF A LOW DEVELOPS AND MOVES UP THE ATLANTIC SEABOARD /ECMWF-YES AND GFS-MAYBE/. IF IT DOES OCCUR...WOULD EXPECT MORE N-NNW WIND LAKE EFFECT...WHILE NW LAKE EFFECT WOULD BE EXPECTED WITHOUT THE LOW. SINCE MODELS ARE MORE CONSISTENT ON LAKE EFFECT POTENTIAL FOR FRIDAY AND THE WEEKEND...WILL CONTINUE TO TREND POPS UP. A LITTLE TOO EARLY TO PIN DOWN TIMING/LOCATION FOR LIKELY POPS...BUT THERE APPEARS TO BE SEVERAL WEAK WAVES MOVING THROUGH THAT WILL INCREASE MOISTURE AND INTENSIFY THE LAKE EFFECT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 125 PM EST MON FEB 11 2013 IFR CONDITIONS WITH LAKE ENHANCED -SN SHOULD PREVAIL AT KIWD/KCMX/KSAW THIS AFTERNOON UNDER GUSTY NNW WINDS ON BACKSIDE OF LOW PRES SYSTEM MOVING EAST OF LAKE SUPEPIOR. MID TO LATE AFTERNOON...IMPROVEMENT INTO THE MVFR RANGE IS EXPECTED AS THE STORM SYSTEM CONTINUES TO MOVE EAST. MVFR CIGS MAY SCATTER OUT LATE TONIGHT AT KIWD AS WINDS BACK TOWARD THE SW...AND PERHAPS AT KSAW UNDER DOWNSLOPING W TO NW WINDS. LOOK FOR MVFR CIGS TO SCT OUT AT BOTH KCMX AND KSAW BY LATE TUE MORNING WITH INCREASED SUBSIDENCE AND RDGG. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 525 AM EST MON FEB 11 2013 ON THE BACKSIDE OF LOW PRES MOVING ACROSS UPPER MI/ERN LAKE SUPERIOR TODAY...EXPECT A PERIOD OF N TO NW GALES TO DEVELOP FROM NW TO SE DURING THE DAY. APPROACHING HIGH PRES RIDGE WILL THEN CAUSE WINDS TO DIMINISH TO UNDER 25 KTS TONIGHT. WINDS WILL BECOME W-SW TUE/TUE NIGHT AS THE RIDGE SHIFTS TO THE E. THE W-SW FLOW WILL BE STRONGEST BTWN THE KEWEENAW AND ISLE ROYALE (POSSIBLY 20-30KT). LIGHTER WINDS UNDER 20KT SHOULD THEN PREVAIL LATER TUE NIGHT THRU WED NIGHT UNDER WEAKER PRES GRADIENT. LOW PRES WILL MOVE ACROSS THE WRN LAKES THU. BEHIND THE LOW...NORTHERLY WINDS WILL INCREASE INTO THE 15-30KT RANGE...STRONGEST OVER CNTRL/ERN LAKE SUPERIOR. FREEZING SPRAY WILL ALSO RETURN AS ARCTIC AIR FLOWS BACK INTO THE UPPER LAKES. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 1 AM EST /MIDNIGHT CST/ TUESDAY FOR MIZ001>003-009. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ004- 005-084. LAKE SUPERIOR... GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LSZ248>250-265-266. GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ264. GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR LSZ263. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...SRF AVIATION...VOSS MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
653 AM EST MON FEB 11 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 525 AM EST MON FEB 11 2013 PER WATER VAPOR IMAGERY AND RUC ANALYSIS...MID LEVEL LOW IS CURRENTLY SPINNING EASTWARD OVER NRN WI ATTM. ASSOCIATED SFC LOW APPEARS TO BE NEARING THE AREA BTWN WATERSMEET AND IRON RIVER. WHILE MAIN BAND OF WAA/ISENTROPIC ASCENT PCPN HAS PUSHED WELL N AND E OF THE AREA...REGIONAL RADAR IMAGERY SHOWS AREAS OF MOSTLY LIGHT PCPN CIRCULATING AROUND THE MID LEVEL LOW. AHEAD OF THE LOW...LOW-LEVELS HAVE WARMED SUFFICIENTLY OVER ROUGHLY THE E HALF OF UPPER MI TO RESULT IN PTYPE BEING JUST RAIN EARLY THIS MORNING (SFC TEMPS HAVE EVEN RISEN TO THE MID/UPPER 30S). PCPN TRANSITIONS BACK TO SNOW OVER WRN UPPER MI AND NW WI. OVER THE NEXT SEVERAL HRS...COLUMN WILL COOL AS MID LEVEL LOW TRACKS EASTWARD. AS A RESULT...WHERE PCPN IS NOW RAIN...IT WILL CHANGE BACK TO ALL SNOW DURING THE MORNING. ATTENTION THEN TURNS TO POTENTIAL LAKE ENHANCEMENT TODAY. IT WON`T BE THE TYPICAL LAKE ENHANCED EVENT PRODUCING MDT/HVY SNOW THAT WOULD NORMALLY BE EXPECTED AT THIS TIME OF YEAR BECAUSE THE AIR MASS IS MILD ACROSS THE AREA RIGHT NOW (850MB TEMPS ARE -1 TO -5C OVER LAKE SUPERIOR). SO INITIALLY...EVEN AS WINDS INCREASE OUT OF THE N TO NW BEHIND SFC LOW...AIR MASS WILL BE TOO WARM FOR LAKE ENHANCEMENT THOUGH THERE WILL BE SOME TERRAIN ENHANCEMENT FROM THE UPSLOPING FLOW. OVER THE W...THERE WILL BE A WINDOW FOR LAKE ENHANCEMENT FROM LATE MORNING INTO THE AFTN AS 850MB TEMPS FALL BLO -7C. INTO NCNTRL UPPER MI...WINDOW LOOKS SHORTER LATE THIS AFTN/EVENING. THUS...PROBABLY SHOULDN`T SEE MUCH MORE THAN 2-4 INCHES OF SNOW OVER THE W TODAY. BEHIND THE SFC LOW...WINDS MORE QUICKLY BACK NW ACROSS NCNTRL UPPER MI WHICH WILL LIMIT LAKE ENHANCEMENT AND MORE QUICKLY DIMINISH TERRAIN ENHANCEMENT INTO MARQUETTE COUNTY. CONSIDERED DROPPING ADVY FOR MARQUETTE COUNTY... BUT WILL WAIT TO SEE HOW THINGS EVOLVE DURING THE MORNING OVER THE W TO GET AN IDEA OF HOW ENHANCEMENT WILL PLAY OUT OVER THE NCNTRL. IT`S POSSIBLE AN ADVY MAY BE NEEDED TO THE E OF MARQUETTE LATER THIS AFTN/EVENING...BUT EXPECTATION IS THAT SNOW ACCUMULATIONS WILL BE UNDER ADVY AMOUNTS. PERIOD OF GUSTY N/NW WINDS TO 30-35MPH ALONG LAKE SUPERIOR NW AND NCNTRL WILL LEAD TO SOME BLSN THIS AFTN/EVENING. AS FOR HEADLINES...CANCELLED ADVY FOR MENOMINEE/DELTA/ALGER EASTWARD AS TEMPS HAVE RISEN TO THE MID/UPPER 30S WITH ONLY RAIN FALLING. REMAINING ADVYS WERE NOT CHANGED. AS DEEPER MOISTURE EXITS TONIGHT...SNOW NEAR LAKE SUPERIOR SHOULD STEADILY DIMINISH W TO E (POSSIBLY EVEN END) AS 850MB TEMPS WILL BE MARGINAL AROUND THE THRESHOLD FOR LES. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 424 AM EST MON FEB 11 2013 LINGERING LIGHT LAKE EFFECT IS EXPECTED FOR THE START OF THE LONG TERM PERIOD. BUT INCREASED DRYING FROM WEST TO EAST...WARMING 850MB TEMPS AND WINDS BACKING TO THE SOUTHWEST WITH THE SURFACE RIDGE MOVING ACROSS THE REGION ON TUESDAY WILL LEAD QUICKLY DIMINISHING LAKE EFFECT SNOW DURING THE DAY TUESDAY. CLOUDS WILL ALSO BE ON THE DECREASE THROUGH THE DAY AND GOING FORECAST HAS A DECENT TREND ON THAT IDEA. THE HIGH PRESSURE RIDGE QUICKLY SLIDES EAST ON TUESDAY AFTERNOON/EVENING AND AREA COMES UNDER THE INFLUENCE OF SEVERAL NORTHERN STREAM WAVES FOR THE REST OF THE WORK WEEK. THE FIRST WAVE...NEAR LAKE WINNIPEG AT 00Z WED...WILL DIVE SOUTHEAST ACROSS LAKE SUPERIOR ON WEDNESDAY. BEST DEEP MOISTURE LOOKS TO STAY OVER THE NORTHEAST HALF OF THE LAKE AND WITH GENERALLY WESTERLY FLOW ACROSS THE CWA...DON/T EXPECT MUCH FOR PRECIPITATION CHANCES ON WEDNESDAY EVEN THOUGH THE BROAD SURFACE TROUGH MOVES THROUGH. THE NEXT SHORTWAVE...TRACKING FARTHER TO THE SOUTHEAST...WILL DEPART ALBERTA ON WEDNESDAY AND MOVE INTO THE NORTHERN PLAINS ON WEDNESDAY EVENING AND THEN TRACK INTO THE WESTERN GREAT LAKES FOR THURSDAY. STILL SOME DIFFERENCES IN THE DETERMINISTIC MODELS AND ENSEMBLE MEMBERS FROM THE GFS/GEM/ECMWF WITH THE STRENGTH OF THIS SHORTWAVE AND THE RESULTING STRENGTH/LOCATION OF THE ASSOCIATED SURFACE LOW. HPC PREFERS A BLEND OF THE 18Z GFES AND 12Z ECMWF ENS MEAN AND THAT SEEMS LIKE A DECENT COMPROMISE. THIS WOULD SWEEP THE SHORTWAVE THROUGH WISCONSIN ON THURSDAY AND HAVE A LOW 1000S MB LOW MOVING THROUGH NORTHERN WISCONSIN OR SOUTHERN UPPER MICHIGAN. AT THIS POINT...WOULD JUST EXPECT A DUSTING TO A COUPLE INCHES OF SNOW WITH THIS SYSTEM...UNLESS THE STRONGER GFS SOLUTION IS CORRECT WHICH WOULD PRODUCE ADVISORY SNOWFALL. ANOTHER SHORTWAVE DIVING SSE ON THE BACK SIDE OF THE THURSDAY SHORTWAVE WILL AMPLIFY THE UPPER TROUGH FURTHER AND LEAD TO IT MERGING WITH THE SOUTHERN STREAM FOR FRIDAY AND THE WEEKEND...WHILE AN UPPER RIDGE BUILDS OVER THE WRN CONUS. THIS WILL ALLOW COLDER AIR TO SPILL SOUTH ACROSS THE UPPER GREAT LAKES REGION AND PRODUCE A PERIOD OF BELOW NORMAL TEMPERATURES THROUGH THE WEEKEND. WITH THIS COLDER AIR...ALSO EXPECT THE AREA TO SEE LAKE EFFECT SNOW DUE TO 850MB TEMPS FALLING TOWARDS -21C BY SATURDAY. WITH A HIGH PRESSURE RIDGE EXPECTED TO BUILD INTO THE NORTHERN PLAINS DURING THIS TIME...WIND DIRECTIONS WILL DEPEND ON IF A LOW DEVELOPS AND MOVES UP THE ATLANTIC SEABOARD /ECMWF-YES AND GFS-MAYBE/. IF IT DOES OCCUR...WOULD EXPECT MORE N-NNW WIND LAKE EFFECT...WHILE NW LAKE EFFECT WOULD BE EXPECTED WITHOUT THE LOW. SINCE MODELS ARE MORE CONSISTENT ON LAKE EFFECT POTENTIAL FOR FRIDAY AND THE WEEKEND...WILL CONTINUE TO TREND POPS UP. A LITTLE TOO EARLY TO PIN DOWN TIMING/LOCATION FOR LIKELY POPS...BUT THERE APPEARS TO BE SEVERAL WEAK WAVES MOVING THROUGH THAT WILL INCREASE MOISTURE AND INTENSIFY THE LAKE EFFECT. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 652 AM EST MON FEB 11 2013 LIFR/IFR CONDITIONS WITH -SN WILL PREVAIL AT KIWD/KCMX/KSAW THROUGH THE MORNING HRS AS A LOW PRES SYSTEM MOVES ACROSS UPPER MI. IN THE WAKE OF THE LOW...EXPECT STRONGER N TO NW WINDS TO DEVELOP FROM W TO E THIS MORNING/EARLY AFTN. GUSTS SHOULD BE IN THE 20-30KT RANGE. MID TO LATE AFTERNOON...IMPROVEMENT INTO THE MVFR RANGE IS EXPECTED AS THE STORM SYSTEM MOVES OFF TO THE EAST. MVFR CIGS MAY SCATTER OUT LATE TONIGHT AT KIWD AS WINDS BACK TOWARD THE SW...AND PERHAPS AT KSAW UNDER DOWNSLOPING W TO NW WINDS. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 525 AM EST MON FEB 11 2013 ON THE BACKSIDE OF LOW PRES MOVING ACROSS UPPER MI/ERN LAKE SUPERIOR TODAY...EXPECT A PERIOD OF N TO NW GALES TO DEVELOP FROM NW TO SE DURING THE DAY. APPROACHING HIGH PRES RIDGE WILL THEN CAUSE WINDS TO DIMINISH TO UNDER 25 KTS TONIGHT. WINDS WILL BECOME W-SW TUE/TUE NIGHT AS THE RIDGE SHIFTS TO THE E. THE W-SW FLOW WILL BE STRONGEST BTWN THE KEWEENAW AND ISLE ROYALE (POSSIBLY 20-30KT). LIGHTER WINDS UNDER 20KT SHOULD THEN PREVAIL LATER TUE NIGHT THRU WED NIGHT UNDER WEAKER PRES GRADIENT. LOW PRES WILL MOVE ACROSS THE WRN LAKES THU. BEHIND THE LOW...NORTHERLY WINDS WILL INCREASE INTO THE 15-30KT RANGE...STRONGEST OVER CNTRL/ERN LAKE SUPERIOR. FREEZING SPRAY WILL ALSO RETURN AS ARCTIC AIR FLOWS BACK INTO THE UPPER LAKES. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 1 AM EST /MIDNIGHT CST/ TUESDAY FOR MIZ001>003-009. WINTER WEATHER ADVISORY UNTIL 10 AM CST THIS MORNING FOR MIZ010- 011. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ004- 005-084. LAKE SUPERIOR... GALE WARNING FROM 1 PM THIS AFTERNOON TO 10 PM EST THIS EVENING FOR LSZ248>250-265-266. GALE WARNING UNTIL 10 AM EST /9 AM CST/ THIS MORNING FOR LSZ162. GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ264. GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR LSZ263. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...SRF AVIATION...ROLFSON MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
526 AM EST MON FEB 11 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 525 AM EST MON FEB 11 2013 PER WATER VAPOR IMAGERY AND RUC ANALYSIS...MID LEVEL LOW IS CURRENTLY SPINNING EASTWARD OVER NRN WI ATTM. ASSOCIATED SFC LOW APPEARS TO BE NEARING THE AREA BTWN WATERSMEET AND IRON RIVER. WHILE MAIN BAND OF WAA/ISENTROPIC ASCENT PCPN HAS PUSHED WELL N AND E OF THE AREA...REGIONAL RADAR IMAGERY SHOWS AREAS OF MOSTLY LIGHT PCPN CIRCULATING AROUND THE MID LEVEL LOW. AHEAD OF THE LOW...LOW-LEVELS HAVE WARMED SUFFICIENTLY OVER ROUGHLY THE E HALF OF UPPER MI TO RESULT IN PTYPE BEING JUST RAIN EARLY THIS MORNING (SFC TEMPS HAVE EVEN RISEN TO THE MID/UPPER 30S). PCPN TRANSITIONS BACK TO SNOW OVER WRN UPPER MI AND NW WI. OVER THE NEXT SEVERAL HRS...COLUMN WILL COOL AS MID LEVEL LOW TRACKS EASTWARD. AS A RESULT...WHERE PCPN IS NOW RAIN...IT WILL CHANGE BACK TO ALL SNOW DURING THE MORNING. ATTENTION THEN TURNS TO POTENTIAL LAKE ENHANCEMENT TODAY. IT WON`T BE THE TYPICAL LAKE ENHANCED EVENT PRODUCING MDT/HVY SNOW THAT WOULD NORMALLY BE EXPECTED AT THIS TIME OF YEAR BECAUSE THE AIR MASS IS MILD ACROSS THE AREA RIGHT NOW (850MB TEMPS ARE -1 TO -5C OVER LAKE SUPERIOR). SO INITIALLY...EVEN AS WINDS INCREASE OUT OF THE N TO NW BEHIND SFC LOW...AIR MASS WILL BE TOO WARM FOR LAKE ENHANCEMENT THOUGH THERE WILL BE SOME TERRAIN ENHANCEMENT FROM THE UPSLOPING FLOW. OVER THE W...THERE WILL BE A WINDOW FOR LAKE ENHANCEMENT FROM LATE MORNING INTO THE AFTN AS 850MB TEMPS FALL BLO -7C. INTO NCNTRL UPPER MI...WINDOW LOOKS SHORTER LATE THIS AFTN/EVENING. THUS...PROBABLY SHOULDN`T SEE MUCH MORE THAN 2-4 INCHES OF SNOW OVER THE W TODAY. BEHIND THE SFC LOW...WINDS MORE QUICKLY BACK NW ACROSS NCNTRL UPPER MI WHICH WILL LIMIT LAKE ENHANCEMENT AND MORE QUICKLY DIMINISH TERRAIN ENHANCEMENT INTO MARQUETTE COUNTY. CONSIDERED DROPPING ADVY FOR MARQUETTE COUNTY... BUT WILL WAIT TO SEE HOW THINGS EVOLVE DURING THE MORNING OVER THE W TO GET AN IDEA OF HOW ENHANCEMENT WILL PLAY OUT OVER THE NCNTRL. IT`S POSSIBLE AN ADVY MAY BE NEEDED TO THE E OF MARQUETTE LATER THIS AFTN/EVENING...BUT EXPECTATION IS THAT SNOW ACCUMULATIONS WILL BE UNDER ADVY AMOUNTS. PERIOD OF GUSTY N/NW WINDS TO 30-35MPH ALONG LAKE SUPERIOR NW AND NCNTRL WILL LEAD TO SOME BLSN THIS AFTN/EVENING. AS FOR HEADLINES...CANCELLED ADVY FOR MENOMINEE/DELTA/ALGER EASTWARD AS TEMPS HAVE RISEN TO THE MID/UPPER 30S WITH ONLY RAIN FALLING. REMAINING ADVYS WERE NOT CHANGED. AS DEEPER MOISTURE EXITS TONIGHT...SNOW NEAR LAKE SUPERIOR SHOULD STEADILY DIMINISH W TO E (POSSIBLY EVEN END) AS 850MB TEMPS WILL BE MARGINAL AROUND THE THRESHOLD FOR LES. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 424 AM EST MON FEB 11 2013 LINGERING LIGHT LAKE EFFECT IS EXPECTED FOR THE START OF THE LONG TERM PERIOD. BUT INCREASED DRYING FROM WEST TO EAST...WARMING 850MB TEMPS AND WINDS BACKING TO THE SOUTHWEST WITH THE SURFACE RIDGE MOVING ACROSS THE REGION ON TUESDAY WILL LEAD QUICKLY DIMINISHING LAKE EFFECT SNOW DURING THE DAY TUESDAY. CLOUDS WILL ALSO BE ON THE DECREASE THROUGH THE DAY AND GOING FORECAST HAS A DECENT TREND ON THAT IDEA. THE HIGH PRESSURE RIDGE QUICKLY SLIDES EAST ON TUESDAY AFTERNOON/EVENING AND AREA COMES UNDER THE INFLUENCE OF SEVERAL NORTHERN STREAM WAVES FOR THE REST OF THE WORK WEEK. THE FIRST WAVE...NEAR LAKE WINNIPEG AT 00Z WED...WILL DIVE SOUTHEAST ACROSS LAKE SUPERIOR ON WEDNESDAY. BEST DEEP MOISTURE LOOKS TO STAY OVER THE NORTHEAST HALF OF THE LAKE AND WITH GENERALLY WESTERLY FLOW ACROSS THE CWA...DON/T EXPECT MUCH FOR PRECIPITATION CHANCES ON WEDNESDAY EVEN THOUGH THE BROAD SURFACE TROUGH MOVES THROUGH. THE NEXT SHORTWAVE...TRACKING FARTHER TO THE SOUTHEAST...WILL DEPART ALBERTA ON WEDNESDAY AND MOVE INTO THE NORTHERN PLAINS ON WEDNESDAY EVENING AND THEN TRACK INTO THE WESTERN GREAT LAKES FOR THURSDAY. STILL SOME DIFFERENCES IN THE DETERMINISTIC MODELS AND ENSEMBLE MEMBERS FROM THE GFS/GEM/ECMWF WITH THE STRENGTH OF THIS SHORTWAVE AND THE RESULTING STRENGTH/LOCATION OF THE ASSOCIATED SURFACE LOW. HPC PREFERS A BLEND OF THE 18Z GFES AND 12Z ECMWF ENS MEAN AND THAT SEEMS LIKE A DECENT COMPROMISE. THIS WOULD SWEEP THE SHORTWAVE THROUGH WISCONSIN ON THURSDAY AND HAVE A LOW 1000S MB LOW MOVING THROUGH NORTHERN WISCONSIN OR SOUTHERN UPPER MICHIGAN. AT THIS POINT...WOULD JUST EXPECT A DUSTING TO A COUPLE INCHES OF SNOW WITH THIS SYSTEM...UNLESS THE STRONGER GFS SOLUTION IS CORRECT WHICH WOULD PRODUCE ADVISORY SNOWFALL. ANOTHER SHORTWAVE DIVING SSE ON THE BACK SIDE OF THE THURSDAY SHORTWAVE WILL AMPLIFY THE UPPER TROUGH FURTHER AND LEAD TO IT MERGING WITH THE SOUTHERN STREAM FOR FRIDAY AND THE WEEKEND...WHILE AN UPPER RIDGE BUILDS OVER THE WRN CONUS. THIS WILL ALLOW COLDER AIR TO SPILL SOUTH ACROSS THE UPPER GREAT LAKES REGION AND PRODUCE A PERIOD OF BELOW NORMAL TEMPERATURES THROUGH THE WEEKEND. WITH THIS COLDER AIR...ALSO EXPECT THE AREA TO SEE LAKE EFFECT SNOW DUE TO 850MB TEMPS FALLING TOWARDS -21C BY SATURDAY. WITH A HIGH PRESSURE RIDGE EXPECTED TO BUILD INTO THE NORTHERN PLAINS DURING THIS TIME...WIND DIRECTIONS WILL DEPEND ON IF A LOW DEVELOPS AND MOVES UP THE ATLANTIC SEABOARD /ECMWF-YES AND GFS-MAYBE/. IF IT DOES OCCUR...WOULD EXPECT MORE N-NNW WIND LAKE EFFECT...WHILE NW LAKE EFFECT WOULD BE EXPECTED WITHOUT THE LOW. SINCE MODELS ARE MORE CONSISTENT ON LAKE EFFECT POTENTIAL FOR FRIDAY AND THE WEEKEND...WILL CONTINUE TO TREND POPS UP. A LITTLE TOO EARLY TO PIN DOWN TIMING/LOCATION FOR LIKELY POPS...BUT THERE APPEARS TO BE SEVERAL WEAK WAVES MOVING THROUGH THAT WILL INCREASE MOISTURE AND INTENSIFY THE LAKE EFFECT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1208 AM EST MON FEB 11 2013 EXPECT PREDOMINANT IFR WITH OCNL LIFR CONDITIONS OVERNIGHT WITH PERIODS OF LIGHT SNOW. VLIFR FOG AT CMX IS EXPECTED TO IMPROVE AS WINDS BACK TO THE NORTHEAST. WITH WINDS BECOMING NORTH TODAY...A PERIOD OF LAKE ENHANCED SNOW WILL HELP KEEP VSBY IN THE IFR RANGE. BY MID TO LATE AFTERNOON...IMPROVEMENT INTO THE MVFR RANGE IS EXPECTED AS THE STORM SYSTEM MOVES OFF TO THE NORTHEAST. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 525 AM EST MON FEB 11 2013 ON THE BACKSIDE OF LOW PRES MOVING ACROSS UPPER MI/ERN LAKE SUPERIOR TODAY...EXPECT A PERIOD OF N TO NW GALES TO DEVELOP FROM NW TO SE DURING THE DAY. APPROACHING HIGH PRES RIDGE WILL THEN CAUSE WINDS TO DIMINISH TO UNDER 25 KTS TONIGHT. WINDS WILL BECOME W-SW TUE/TUE NIGHT AS THE RIDGE SHIFTS TO THE E. THE W-SW FLOW WILL BE STRONGEST BTWN THE KEWEENAW AND ISLE ROYALE (POSSIBLY 20-30KT). LIGHTER WINDS UNDER 20KT SHOULD THEN PREVAIL LATER TUE NIGHT THRU WED NIGHT UNDER WEAKER PRES GRADIENT. LOW PRES WILL MOVE ACROSS THE WRN LAKES THU. BEHIND THE LOW...NORTHERLY WINDS WILL INCREASE INTO THE 15-30KT RANGE...STRONGEST OVER CNTRL/ERN LAKE SUPERIOR. FREEZING SPRAY WILL ALSO RETURN AS ARCTIC AIR FLOWS BACK INTO THE UPPER LAKES. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 1 AM EST /MIDNIGHT CST/ TUESDAY FOR MIZ001>003-009. WINTER WEATHER ADVISORY UNTIL 10 AM CST THIS MORNING FOR MIZ010- 011. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ004- 005-084. LAKE SUPERIOR... GALE WARNING FROM 1 PM THIS AFTERNOON TO 10 PM EST THIS EVENING FOR LSZ248>250-265-266. GALE WARNING UNTIL 10 AM EST /9 AM CST/ THIS MORNING FOR LSZ162. GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ264. GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR LSZ263. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...SRF AVIATION...JLB MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS DULUTH MN
1136 PM CST SUN FEB 10 2013 .AVIATION...06Z TAFS A MIXTURE OF IFR AND MVFR CONDITIONS COVERED THE NORTHLAND IN AREAS OF LIGHT SNOW...WITH AREAS OF FREEZING DRIZZLE ALSO OCCURRING. THE FREEZING DRIZZLE WAS FALLING MAINLY OVER SOUTHERN AREAS. THE PRECIPITATION SHOULD DIMINISH IN INTENSITY LATE TONIGHT OR MONDAY MORNING FOR MOST AREAS. VSBYS WILL RISE AS THE PRECIP INTENSITY DIMINISHES...AND CEILINGS WILL INCREASE THROUGH THE DAY AS WELL. CEILINGS MAY RISE TO OR SCATTER OUT AND BECOME VFR LATE IN THE PERIOD...MAINLY OVER WESTERN TAF SITES. && .PREV DISCUSSION... /ISSUED 938 PM CST SUN FEB 10 2013/ UPDATE... PRECIPITATION RATES HAVE DIMINISHED THIS EVENING FOR MUCH OF THE NORTHLAND...AND AS THAT HAS HAPPENED MORE FREEZING DRIZZLE HAS DEVELOPED. AN AREA OF HEAVIER PRECIPITATION WAS ROTATING NORTH TOWARD PRICE/SAWYER/WASHBURN COUNTIES AND MOST OBSERVATIONS UNDER THIS PRECIP HAS BEEN RAIN. GIVEN SURFACE TEMPS AND ROAD TEMPS ARE LIKELY AT OR BELOW FREEZING OVER MUCH OF THAT AREA...WE ADDED FREEZING RAIN TO THE FORECAST. THE HEAVY SNOW BAND WAS ROTATING THROUGH OUR EXTREME NORTH CENTRAL/NORTHWEST ZONES AS OF 930 PM...AND PRECIP RATES THERE SHOULD DIMINISH LATER THIS EVENING. WE KEPT ALL THE WARNINGS GOING...BUT DID MAKE SOME CHANGES TO THE EXPIRATION. WE CHANGED THE EXPIRATION OF MOST OF THE SOUTHERN HALF TO 6 AM MONDAY MORNING...HAVE THE NORTH HALF AT 18Z. THE SOUTH SHORE IS A BIT MORE OF A CHALLENGE. THE SETUP FOR LAKE EFFECT SNOW IS NOT IDEAL...AS STABILITY ISN`T AS LOW AS WE`D LIKE TO SEE. BASED ON THE POSSIBILITY OF LAKE ENHANCED SNOWFALL AS 850MB TEMPERATURES DROP IN THE AFTERNOON...WE KEPT THE EXPIRATION OF THE WARNING FOR BAYFIELD...ASHLAND AND IRON COUNTIES AT 6 PM MONDAY. THE DOUGLAS COUNTY WARNING WE CHANGED TO NOON MONDAY. LAKE ENHANCED SNOWFALL WILL NOT OCCUR THERE...BUT THERE IS A CHANCE FOR A GRAVITY WAVE INDUCED BAND OF SNOWFALL TO DEVELOP LATE TONIGHT INTO MONDAY MORNING AS WINDS TURN NORTH TO NORTHWEST. THE RAP IS SHOWING A FAIRLY STRONG GRAVITY WAVE SIGNAL...AND THE NAM BUFR SOUNDINGS SHOW A PRETTY GOOD INVERSION DEVELOPING AROUND 2300FT AGL BY 15Z. WE INCREASED SNOWFALL IN A BAND FROM NORTH CENTRAL/NORTHWEST DOUGLAS COUNTY INTO SOUTHWEST DOUGLAS/EASTERN CARLTON COUNTIES. LATER SHIFTS WILL HAVE TO MONITOR THIS CLOSELY AS WE MAY NEED TO INCREASE SNOWFALL THERE FURTHER. PREV DISCUSSION... /ISSUED 721 PM CST SUN FEB 10 2013/ UPDATE... THE AREA OF VERY HEAVY SNOW...WITH RATES IN EXCESS OF OF AN INCH PER HOUR HAS MOVED INTO FAR NORTHERN MINNESOTA. RADAR WAS SHOWING OTHER AREAS OF SNOW...MOST MUCH LIGHTER...FURTHER SOUTH. A FEW SPOTTERS HAVE REPORTED THE SNOW HAD ENDED FOR NOW...LIKE AT GURNEY. WE EXPECT SNOW TO CONTINUE TONIGHT WITH AMOUNTS RANGING FROM 3 TO 6 INCHES ACROSS THE FAR NORTH WHERE FORCING WILL LAST LONGER. AREAS FURTHER SOUTH WILL RANGE FROM 1 TO 4 INCHES TONIGHT...WITH FREEZING DRIZZLE OR FREEZING RAIN POSSIBLE OVER ABOUT THE SOUTHERN HALF OF THE NORTHLAND. IT WILL BE MOST LIKELY IN NORTHWEST WISCONSIN WHERE SOUNDINGS SHOW THE BEST FREEZING DRIZZLE SOUNDINGS. AN AREA OF HEAVIER PRECIPITATION WAS MOVING NORTH TOWARD NORTHERN WISCONSIN...AND OBSERVATIONS UNDER THIS AREA OF PRECIPITATION INDICATE MOSTLY RAIN...SO WE`LL HAVE TO WATCH CLOSELY AS IT MOVES FURTHER NORTH. AT THIS TIME...WE DID LEAVE ALL THE HEADLINES ALONE...WHICH EXPIRE AT 00Z TUE. WE WILL LIKELY BE ABLE TO CANCEL SOME OF THESE EARLIER...BUT WILL WAIT A BIT LONGER TO DO SO. ADDITIONAL SNOWFALL ON MONDAY LOOKS TO BE LIMITED...BUT WOULD LIKE TO SEE SOME NEW GUIDANCE BEFORE MAKING TO MANY DRASTIC CHANGES. THE EASTERN CWA COULD SEE THE SNOW LINGER LONGEST...AND ACCUMULATIONS COULD BE AN INCH OR TWO IN THE EAST. PREV DISCUSSION... /ISSUED 539 PM CST SUN FEB 10 2013/ AVIATION...00Z TAFS WIDESPREAD VLIFR/IFR CONDITIONS WILL OCCUR ACROSS MOST AREAS TONIGHT...WITH THE VLIFR CONDITIONS MOST WIDESPREAD ACROSS FAR NORTHERN MINNESOTA WHERE MANY OBSERVATIONS HAD 0.5SM OR LESS IN SNOW. THE SNOW INTENSITY WILL DIMINISH AS THE EVENING PROGRESSES FOR MOST AREAS OVERNIGHT...BUT THERE WILL STILL BE POCKETS OF HEAVIER SNOW. CONDITIONS WILL IMPROVE FURTHER ON MONDAY. EAST/NORTHEAST WILL VEER TO NORTH TO NORTHWEST BY 12Z. PREV DISCUSSION... /ISSUED 300 PM CST SUN FEB 10 2013/ SHORT TERM...TONIGHT THROUGH MONDAY NIGHT. LOW PRESSURE OVER NORTHERN IOWA WILL CONTINUE TO BRING SNOW TO MOST OF THE NORTHLAND THIS EVENING. SOME LIGHT FREEZING RAIN AND SLEET WILL STILL MIX IN WITH THE SNOW LATE THIS AFTERNOON OVER NORTHWESTERN WISCONSIN. NORTHERLY WINDS AT 15 TO 20 MPH...WITH A FEW GUSTS TO 25 MPH...ACROSS NORTHEASTERN MINNESOTA MAY LEAD TO SOME BLOWING AND DRIFTING OF THE SNOW. WINDS WILL BE STRONGER NEAR LAKE SUPERIOR. SNOW INTENSITY WILL COME DOWN A BIT AS THE LOW MOVES NORTHEASTWARD INTO WISCONSIN LATE TONIGHT. THE CENTER OF THE LOW WILL BE OVER THE UPPER PENINSULA OF MICHIGAN ON MONDAY MORNING AND LIGHT SNOW WILL PERSIST OVER THE AREA. ADDITIONAL ACCUMULATIONS DURING THE DAY ON MONDAY WILL GENERALLY BE UNDER AN INCH. WINDS WILL BECOME MORE NORTHWESTERLY ON MONDAY AND THERE WILL BE SOME LAKE ENHANCEMENT OF THE SNOW FOR THE GOGEBIC RANGE WHERE THERE COULD BE UP TO TWO ADDITIONAL INCHES OF SNOW DURING THE DAY. THE LOW PUSHES INTO EASTERN ONTARIO MONDAY NIGHT AND THE SNOW WILL END OVER MOST OF THE NORTHLAND EXCEPT FOR AREAS OF THE SOUTH SHORE OF LAKE SUPERIOR WHERE A FEW SNOW SHOWERS WILL LINGER DURING THE EVENING HOURS. HIGH PRESSURE WILL BEGIN TO BUILD IN FROM THE CENTRAL PLAINS LATE MONDAY NIGHT. LONG TERM...TUESDAY THROUGH SUNDAY. SOME LIGHT SNOW WILL BE POSSIBLE ACROSS THE AREA ON WEDNESDAY AFTERNOON...AS A LOW PRESSURE SYSTEM MOVES TO THE FARGO AREA BY 00Z THURSDAY. THE LOW WILL THEN MOVE ACROSS CENTRAL MN AND INTO NORTHERN TO CENTRAL WISCONSIN BY 12Z THURSDAY. HAVE INCREASED POPS ACROSS THE AREA FOR WEDNESDAY NIGHT AND THURSDAY AS THE MODELS ARE COMING INTO BETTER AGREEMENT CONCERNING THIS SYSTEM. THE GFS CONTINUES TO BE STRONGER THAN THE ECMWF...BUT YESTERDAY THE ECMWF DID NOT EVEN INDICATE THIS SYSTEM SO IT IS LIKELY LATCHING ONTO IT BETTER. COLDER AIR WILL DRAG SOUTHWARD BEHIND THE DEPARTING SYSTEM ON THURSDAY AND FRIDAY. GENERALLY DRY AND COOLER WEATHER IS THEN IN STORE FOR SATURDAY AND SUNDAY. OVERALL NOT TOO MUCH IN THE WAY OF PRECIPITATION THIS PERIOD WITH THE EXCEPTION OF A FEW INCHES OF SNOW BEING POSSIBLE MID WEEK. TEMPS WILL BE ABOVE NORMAL FOR MUCH OF THE EXTENDED...BUT IT WILL BE A BIT COOLER FOR THE WEEKEND. AVIATION.../18Z TAF ISSUANCE/ A WINTER STORM WILL AFFECT THE NORTHLAND DURING THE TAF PERIOD. THE STORM WILL BRING AN INCREASE IN SNOW AND POSSIBLY SOME SNOW/ICE MIX IN EASTERN AREAS. CIGS AND VSBYS WILL GENERALLY BE IN THE IFR/LIFR/VLIFR RANGE THROUGHOUT THE PERIOD...BUT TRANSITIONING TO MORE OF AN MVFR SITUATION ON MONDAY MORNING. SNOW WILL COME DOWN VERY HARD AT TIMES...WITH VSBYS LESS THAN A QUARTER MILE. && .POINT TEMPS/POPS... DLH 23 25 9 26 / 100 80 10 0 INL 18 22 7 26 / 100 90 10 0 BRD 24 26 9 27 / 100 80 10 0 HYR 26 29 10 27 / 100 90 10 0 ASX 27 29 11 27 / 100 90 20 0 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL NOON CST MONDAY FOR MNZ010>012- 018>021. WINTER STORM WARNING UNTIL 6 AM CST MONDAY FOR MNZ025-026- 033>038. WI...WINTER STORM WARNING UNTIL NOON CST MONDAY FOR WIZ001. WINTER STORM WARNING UNTIL 6 AM CST MONDAY FOR WIZ006>009. WINTER STORM WARNING UNTIL 6 PM CST MONDAY FOR WIZ002>004. && $$ SHORT TERM...MELDE AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1121 AM CST MON FEB 11 2013 .AVIATION...18Z KGRI TAF. VFR CONDITIONS TO CONTINUE THROUGH THE NEXT 24 HOURS. MID TO HIGH LEVEL CLOUDS WILL BE POSSIBLE AT THE TERMINAL DURING THE TAF PERIOD...BUT NOTHING BELOW 7000FT AGL CURRENTLY FORECAST. THE SURFACE WIND WILL REMAIN FROM THE NORTHWEST TODAY...SUSTAINED AT AROUND 17KTS AND GUSTING AROUND 23KTS. THIS WIND WILL DIMINISH THROUGH THE AFTERNOON HOURS AND EVENTUALLY BECOME LIGHT AND VARIABLE OVERNIGHT BEFORE BECOMING MORE ESTABLISHED FROM THE SOUTHWEST DURING THE DAY TUESDAY. VISIBILITY RESTRICTION IS NOT EXPECTED AT KGRI THROUGH THE NEXT 24 HOURS. && .PREV DISCUSSION... /ISSUED 433 AM CST MON FEB 11 2013/ SHORT TERM...THROUGH WEDNESDAY NIGHT. COMPARED TO THE PAST FEW DAYS...THESE NEXT 72 HOURS ARE LOOKING FAIRLY BENIGN WITH ESSENTIALLY ZERO RISK OF PRECIPITATION. HOWEVER...BOTH TUESDAY AND ESPECIALLY WEDNESDAY ARE TRENDING A BIT BREEZIER THAN PREVIOUSLY ADVERTISED...BUT ALSO A BIT WARMER AS WELL. 09Z OBJECTIVE SURFACE ANALYSIS PLACED THE CENTER OF THE DEPARTING...STRONG 991MB LOW OVER CENTRAL WI...WITH THE CENTRAL PLAINS CAUGHT WITHIN THE BACKSIDE OF THE TIGHT PRESSURE GRADIENT BETWEEN THIS LOW AND A ROUGHLY 1024MB HIGH OVER WY. A FAIRLY PRONOUNCED GRADIENT IN WIND SPEEDS IS EVIDENT ACROSS THE CWA AT THIS TIME...WITH NORTHWESTERLY SPEEDS AVERAGING NO MORE THAN 10-15 MPH IN SOUTHWEST AREAS...WHILE MOST CENTRAL/NORTHEAST AREAS CONTINUE TO REPORT SUSTAINED SPEEDS AT LEAST 15-20 MPH WITH GUSTS UP TO NEAR 30 MPH. FORTUNATELY THOUGH...SPEEDS HAVE FINALLY EASED WELL BELOW ADVISORY CRITERIA...WHICH TOOK A FEW HOURS LONGER EARLIER TONIGHT THAN ORIGINALLY THOUGHT. ANY LINGERING FLURRIES FROM EARLIER TONIGHT HAVE ALSO DEPARTED TO THE NORTHEAST...WITH IN FACT NEARLY FULLY CLEAR SKIES NOW OVER ALL BUT THE FAR EASTERN EDGES OF THE CWA WHERE SOME LOW STRATUS LINGERS. PRE-DAWN TEMPERATURES ARE FAIRLY UNIFORM ACROSS THE CWA...WITH MOST AREAS LIKELY HEADING FOR LOWS SOMEWHERE BETWEEN 21-27. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA CONFIRMED AN ACTIVE PATTERN ACROSS THE CONUS...WITH THE NEARLY VERTICALLY STACKED CLOSED LOW DEPARTING OVER THE WI AREA...WHILE OFF TO OUR SOUTHWEST...A CURRENTLY OPEN 500MB SHORTWAVE TROUGH WAS CENTERED NEAR THE CA/NV/UT/AZ BORDERS...WITH ONLY THE SLIGHTEST HINT OF SHORTWAVE RIDGING OVER THE CENTRAL HIGH PLAINS IN BETWEEN THESE TWO PRIMARY LOWS. FORECAST-WISE TODAY...WHILE BY NO MEANS AS WINDY AS YESTERDAY...A HEALTHY NORTHWEST BREEZE OF 15-20 MPH WITH GUSTS 25+ MPH WILL PERSIST WELL INTO THE EARLY-MID AFTERNOON HOURS ACROSS ROUGHLY THE NORTHEAST 1/2 OF THE CWA THANKS TO EFFICIENT MIXING TO AROUND 850MB...BEFORE EASING MORE NOTICEABLY BETWEEN 3 PM AND SUNSET. ANY LINGERING/PRESUMABLY MINOR BLOWING SNOW ISSUES IN THE ORD AREA SHOULD CONTINUE TO ABATE WITH TIME. WIND SPEEDS ACROSS ROUGHLY THE SOUTHWEST 1/2 OF THE AREA WILL AVERAGE AT LEAST 5 MPH LIGHTER...AND ALSO START TO EASE UP SOONER ESPECIALLY THIS AFTERNOON AS A BROAD 1025MB RIDGE AXIS SETTLES INTO THE AREA. CLOUD-WISE...WHILE NEARLY THE ENTIRE AREA WILL START OUT WITH PLENTY OF SUNSHINE...THE AFTERNOON HOURS WILL BRING AT LEAST PARTLY CLOUDY SKIES TO MAINLY THE SOUTHWEST 1/2 OF THE CWA AS MID- HIGH CLOUDS SPREAD OVERHEAD DOWNSTREAM FROM THE SOUTHWEST CONUS LOW. THERE ARE SUGGESTIONS FROM THE LATEST HRRR RUNS THAT SOME SCATTERED LOW CLOUDS COULD ALSO INCREASE MAINLY THIS AFTERNOON IN SOME AREAS NORTH OF I-80...BUT WILL KEEP IT A MOSTLY SUNNY THEME HERE AT LEAST FOR NOW. AS FOR TEMPS...FOLLOWED THE 00Z NAM/05Z RAP SOLUTION RATHER CLOSELY...WHICH RESULTED IN A 1-3 DEGREE UPWARD NUDGE FROM PREVIOUS FORECAST...NOW RANGING FROM LOW 30S FAR NORTH...MID 30S CENTRAL...LOW 40S SOUTH MAINLY KS ZONES. ITS WORTH NOTING THAT THE 06Z NAM CAME IN COLDER FOR NORTHWEST COUNTIES...BUT THIS APPEARS TO BE A RESULT OF AN OVERDONE MODEL- INITIALIZED SNOW FIELD. THAT BEING SAID...CONFIDENCE IN TEMPS ISN/T QUITE AS HIGH ESPECIALLY FOR THE ORD AREA...WHERE A LIGHT COATING OF SNOW FROM YESTERDAY ALONG WITH A WIND DIRECTION BLOWING OFF OF THE DEEPER SNOW COVER OVER THE SANDHILLS COULD WORK TO HOLD THINGS DOWN A BIT. THIS EVENING/TONIGHT...CONFIDENCE REMAINS HIGH THAT THE ENTIRE CWA REMAINS PRECIPITATION-FREE...BUT THINGS DEFINITELY START TO TURN MORE INTERESTING A FEW COUNTIES TO OUR SOUTH...AS THE AFOREMENTIONED SOUTHWESTERN CONUS MID LEVEL SHORTWAVE TROUGH STARTS CLOSING OFF A BIT AS IT HEADS EAST INTO NM. FORCING DOWNSTREAM FROM THIS WAVE WILL SPREAD DECENT CHANCES FOR AT LEAST LIGHT ACCUMULATING SNOW INTO MAINLY THE SOUTHWEST 1/4 OF KS ESPECIALLY AFTER MIDNIGHT. WHILE A CONSENSUS OF VARIOUS MODELS SUCH AS THE NAM/ECMWF/4KM WRF-NMM KEEPS ANY OF THIS SNOW AT LEAST 80 MILES SOUTH OF THE FAR SOUTHERN CWA...THE NEW 06Z GFS HAS SUDDENLY TRENDED SLIGHTLY FARTHER NORTH...BRINGING AT LEAST A DUSTING OF SNOW WITHIN ROUGHLY 20 MILES OF FAR SOUTHERN ROOKS/OSBORNE COUNTIES. FOR NOW WILL DISCOUNT THIS RUN AS A NORTHERN OUTLIER AND STAND FIRM THAT THIS SYSTEM WILL NOT BE AN ISSUE FOR OUR CWA...AND BRING ONLY A PERIOD OF PARTLY/MOSTLY CLOUDY SKIES TO MAINLY OUR SOUTHERN COUNTIES. AT THE SURFACE TONIGHT...INITIALLY FAIRLY LIGHT/VARIABLE WINDS NEAR THE RIDGE AXIS WILL TAKE ON A SLIGHTLY STEADIER SOUTHWESTERLY COMPONENT LATE IN THE NIGHT IN RESPONSE TO A SUBTLE PASSING TROUGH AXIS. GIVEN THESE LIGHT WESTERLY BREEZES AND ALSO A FAIR AMOUNT OF PASSING CLOUD ESPECIALLY SOUTH...GENERALLY RAISED LOW TEMPS 2-4 DEGREES FROM PREVIOUS GRIDS...WITH ALL BUT FAR NORTHWESTERN AREAS HOLDING UP GENERALLY 17-22. TUESDAY DAYTIME...IN A CONTINUATION FROM LATE WED NIGHT ACCUMULATING SNOW WILL CONTINUE TO OUR SOUTH...TRACKING EASTWARD MAINLY ALONG/SOUTH OF THE KS/OK BORDER...AS THE PRIMARY 500MB SHORTWAVE ENDS UP OVER SOUTHERN/WESTERN OK BY DAYS END. AGAIN THOUGH...NO LOCAL IMPACT ANTICIPATED OTHER THAN MORE MID-HIGH CLOUD OVER KS ZONES VERSUS NEB ZONES. AT THE SURFACE...HIGH PRESSURE CENTERED TO THE WEST WILL DRIVE A WESTERLY DOWNSLOPE WIND COMPONENT ACROSS THE ENTIRE CWA...AND HAVE INCREASED SUSTAINED SPEEDS CLOSER TO 15 MPH WITH HIGHER GUSTS MAINLY FOR THE NORTHERN 1/2 OF THE CWA. ASSUMING THAT SUNSHINE IS FAIRLY PLENTIFUL IN MOST AREAS...AND GIVEN SLIGHT LOW LEVEL WARMING VERSUS MONDAY...SEE LITTLE REASON WHY THIS DOWNSLOPE WIND WON/T BRING A DECENT BOOST IN HIGH TEMPS...AND HAVE RAISED HIGHS GENERALLY 2-4 DEGREES FROM PREVIOUS FORECAST...ESPECIALLY IN EASTERN AREAS FARTHEST REMOVED FROM THE WESTERN/NORTH CENTRAL NEB SNOW FIELD. THIS NOW YIELDS HIGHS IN THE MID-UPPER 40S MOST AREAS...EXCEPT LOW 40S FAR NORTHWEST. TUESDAY NIGHT...THE SOUTHERN CONUS SHORTWAVE TROUGH TREKS EAST INTO THE AR/TN AREA...HELPING TRANSITION THE FLOW OVER THE CENTRAL PLAINS TO MORE PRONOUNCED NORTHWESTERLY...BUT WITH NO IMPACTFUL DISTURBANCES. ALTHOUGH A DECENT BATCH OF MID LEVEL CLOUDS COULD SAG SOUTHWARD ACROSS THE CWA...NOT EVEN EXPECTING FLURRIES AT THIS TIME. AT THE SURFACE...A LIGHT BUT STEADY 5-10 MPH WESTERN COMPONENT SHOULD AGAIN HELP KEEP TEMPS FROM FALLING TOO FAR...AND NUDGED UP PREVIOUS LOWS VERY SLIGHTLY...KEEPING MOST PLACES UP BETWEEN 21-24 DEGREES. WEDNESDAY...DRY NORTHWESTERLY FLOW ALOFT PERSISTS...AS THE LOCAL AREA REMAINS DOWNSTREAM FROM A LOW AMPLITUDE/CLIPPER-TYPE SHORTWAVE TROUGH SLIPPING OUT OF CANADA TO THE DAKOTAS/MN BORDER AREA BY DAYS END. UNDER GENERALLY PARTLY CLOUDY SKIES...A CONTINUED DOWNSLOPE WESTERLY WIND AND WARMER AIR EVIDENT ABOVE THE SURFACE AT 850MB SHOULD CONTINUE THE WARMING TREND FROM TUESDAY...AND HAVE MADE A VERY SLIGHT UPWARD NUDGE TO PREVIOUS HIGHS WITH MOST OF THE CWA INTO THE 50-53 RANGE...EXCEPT COOLER MID-UPPER 40S MAINLY IN OUR FAR NORTH/NORTHWEST FRINGES WHERE THE SNOW FIELD COULD STILL POSSIBLY EXERT SOME INFLUENCE. THE OVERALL BIGGEST CHANCE TO WEDNESDAY INVOLVED WIND SPEEDS...WHICH WERE UPPED AT LEAST 6-8 MPH FROM PREVIOUS GRIDS INTO BREEZY TERRITORY...AND NOW EXPECT SEVERAL HOURS OF SUSTAINED WEST-NORTHWEST SPEEDS 15-20 MPH WITH SOME HIGHER GUSTS. FORTUNATELY FOR POSSIBLE FIRE WEATHER CONCERNS...RELATIVE HUMIDITY VALUES ARE FORECAST TO FALL NO LOWER THAN THE UPPER-20S PERCENT...AND THIS IS ONLY IN A SMALL PART OF KS ZONES. WEDNESDAY NIGHT...THE AFOREMENTIONED NORTHERN PLAINS CLIPPER-SYSTEM DIVES DOWN MAINLY INTO IA/WI...WHILE AT THE SURFACE THE LEADING EDGES OF A MODEST COLD FRONT WILL ENTER THE LOCAL AREA. ALTHOUGH THE ORIENTATION OF THE UPPER JET ON THE WESTERN SIDE OF THIS DISTURBANCE ALONG WITH SOME MID LEVEL RH PROGS FROM MODELS SUCH AS THE 06Z NAM SUGGEST THAT A FEW FLURRIES MIGHT NOT BE OUT OF THE QUESTION FOR PARTS OF THE CWA...WILL KEEP ALL PRECIP MENTION OUT FOR NOW WITH POSSIBLY SLIGHTLY BETTER FLURRY CHANCES HOLDING OFF UNTIL THE THURS DAYTIME HOURS. MADE VERY LITTLE CHANGE TO LOW TEMPS WITH MID-UPPER 20S ALL AREAS. LONG TERM...THURSDAY THROUGH SUNDAY...AT THE ONSET OF THE EXTENDED PERIODS...100KT TO 120KT JET H3 JET STREAKS WILL NOSE SOUTH FM ALBERTA ACROSS THE EASTERN SLOPES OF THE NORTHERN ROCKIES CARVING A TROUGH ACROSS THE EASTERN TWO THIRDS OF THE CONUS. IN A NORTHWEST FLOW REGIME ACROSS THE CENTRAL PLAINS...COLD AIR WILL BACK IN FM THE NORTHEAST WITH THE MAIN THERMAL TROUGH ORIENTED FM ONTARIO THRU THE GREAT LAKES REGION. ENERGY TRANSLATING SOUTHEAST THRU FLOW AND A PUSH OF COLD AIR SOUTH THURSDAY COULD GENERATE SNOW FLURRIES IN OUR NORTHERN ZONES. FRIDAY WILL SEE A REINFORCING SHOT OF COLD AIR AS A STRONGER JET STREAK DIVES SOUTH ALONG THE FRONT RANGE OF THE ROCKIES AND ADDITIONAL SHORTWAVE ENERGY TRANSLATES ON THE WESTERN EDGE OF THE TROUGH WHICH ULTIMATELY FURTHER DEEPENS TO THE TROUGH ACROSS CENTRAL AND EASTERN CONUS. CURRENTLY HAVE FLURRIES IN THE FORECAST ON FRIDAY AND THIS IS STILL WARRANTED WITH FROPA/UPPER DYNAMICS. TEMPS WILL TREND COLDER THURSDAY...CLOSER TO SEASONAL NORMALS...AND WILL DROP FURTHER FRIDAY WITH STRONGER COLD FRONT. A COLD SURFACE HIGH PRESSURE SYSTEM WILL SETTLE ACROSS THE CENTRAL PLAINS BEHIND THE FRONT FRIDAY NIGHT...WHICH WILL RESULT IN TEMPS IN THE TEENS FOR LOWS. AFTER A COLD COUPLE OF DAYS FOR THE END OF THE WORKWEEK...THE WEATHER OVER THE WEEKEND TRENDS WARMER. THE SFC RIDGE AXIS SLIDES SOUTHEAST ON SATURDAY...ALLOWING FOR RETURN FLOW...AND ALOFT...THE UPPER TROUGH DEPARTS EASTWARD AND HEIGHTS BEGIN TO RISE ACROSS THE CENTRAL PLAINS. BY SUNDAY THE RIDGE WHICH WAS OVER THE ROCKIES SATURDAY REACHES THE INTERIOR CONUS..AND WARMER AIR SPREADS EASTWARD. SUNDAY IS LOOKING LIKE THE WARMEST OF THE EXTENDED PERIODS WITH HIGHS IN THE 40S FOR THE MOST PART AND 50S MAY NOT BE OUT OF THE QUESTION. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ AVIATION...BRYANT SHORT TERM...PFANNKUCH LONG TERM...FAY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
524 AM CST MON FEB 11 2013 .AVIATION...12Z TAF. MAIN CONCERN FOR THE FIRST PART OF THE TAF PERIOD IS GUSTY NORTHWEST WINDS AS SFC PRESSURE GRADIENT WILL REMAIN TIGHT THRU THE MORNING. WIND GUSTS NEAR 25KTS ARE POSSIBLE UNTIL GRADIENT RELAXES THIS AFTN/EVENING AS SFC HIGH PRESSURE SETTLES ONTO THE CENTRAL PLAINS. KGRI WILL BE ON THE SOUTHWEST EDGE OF MVFR CLOUDS THIS MORNING...BUT BRUNT OF LOW CLOUDS ARE EXPECTED TO REMAIN EAST AS THE UPPER LOW PRESSURE SYSTEM CONTINUES TO LIFT OUT AND DID NOT BRING ANY CIGS INTO THE TERMINAL...THEN SCATTERED MID/HIGH CLOUDS ARE EXPECTED TONIGHT. && .PREV DISCUSSION... /ISSUED 433 AM CST MON FEB 11 2013/ SHORT TERM...THROUGH WEDNESDAY NIGHT. COMPARED TO THE PAST FEW DAYS...THESE NEXT 72 HOURS ARE LOOKING FAIRLY BENIGN WITH ESSENTIALLY ZERO RISK OF PRECIPITATION. HOWEVER...BOTH TUESDAY AND ESPECIALLY WEDNESDAY ARE TRENDING A BIT BREEZIER THAN PREVIOUSLY ADVERTISED...BUT ALSO A BIT WARMER AS WELL. 09Z OBJECTIVE SURFACE ANALYSIS PLACED THE CENTER OF THE DEPARTING...STRONG 991MB LOW OVER CENTRAL WI...WITH THE CENTRAL PLAINS CAUGHT WITHIN THE BACKSIDE OF THE TIGHT PRESSURE GRADIENT BETWEEN THIS LOW AND A ROUGHLY 1024MB HIGH OVER WY. A FAIRLY PRONOUNCED GRADIENT IN WIND SPEEDS IS EVIDENT ACROSS THE CWA AT THIS TIME...WITH NORTHWESTERLY SPEEDS AVERAGING NO MORE THAN 10-15 MPH IN SOUTHWEST AREAS...WHILE MOST CENTRAL/NORTHEAST AREAS CONTINUE TO REPORT SUSTAINED SPEEDS AT LEAST 15-20 MPH WITH GUSTS UP TO NEAR 30 MPH. FORTUNATELY THOUGH...SPEEDS HAVE FINALLY EASED WELL BELOW ADVISORY CRITERIA...WHICH TOOK A FEW HOURS LONGER EARLIER TONIGHT THAN ORIGINALLY THOUGHT. ANY LINGERING FLURRIES FROM EARLIER TONIGHT HAVE ALSO DEPARTED TO THE NORTHEAST...WITH IN FACT NEARLY FULLY CLEAR SKIES NOW OVER ALL BUT THE FAR EASTERN EDGES OF THE CWA WHERE SOME LOW STRATUS LINGERS. PRE-DAWN TEMPERATURES ARE FAIRLY UNIFORM ACROSS THE CWA...WITH MOST AREAS LIKELY HEADING FOR LOWS SOMEWHERE BETWEEN 21-27. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA CONFIRMED AN ACTIVE PATTERN ACROSS THE CONUS...WITH THE NEARLY VERTICALLY STACKED CLOSED LOW DEPARTING OVER THE WI AREA...WHILE OFF TO OUR SOUTHWEST...A CURRENTLY OPEN 500MB SHORTWAVE TROUGH WAS CENTERED NEAR THE CA/NV/UT/AZ BORDERS...WITH ONLY THE SLIGHTEST HINT OF SHORTWAVE RIDGING OVER THE CENTRAL HIGH PLAINS IN BETWEEN THESE TWO PRIMARY LOWS. FORECAST-WISE TODAY...WHILE BY NO MEANS AS WINDY AS YESTERDAY...A HEALTHY NORTHWEST BREEZE OF 15-20 MPH WITH GUSTS 25+ MPH WILL PERSIST WELL INTO THE EARLY-MID AFTERNOON HOURS ACROSS ROUGHLY THE NORTHEAST 1/2 OF THE CWA THANKS TO EFFICIENT MIXING TO AROUND 850MB...BEFORE EASING MORE NOTICEABLY BETWEEN 3 PM AND SUNSET. ANY LINGERING/PRESUMABLY MINOR BLOWING SNOW ISSUES IN THE ORD AREA SHOULD CONTINUE TO ABATE WITH TIME. WIND SPEEDS ACROSS ROUGHLY THE SOUTHWEST 1/2 OF THE AREA WILL AVERAGE AT LEAST 5 MPH LIGHTER...AND ALSO START TO EASE UP SOONER ESPECIALLY THIS AFTERNOON AS A BROAD 1025MB RIDGE AXIS SETTLES INTO THE AREA. CLOUD-WISE...WHILE NEARLY THE ENTIRE AREA WILL START OUT WITH PLENTY OF SUNSHINE...THE AFTERNOON HOURS WILL BRING AT LEAST PARTLY CLOUDY SKIES TO MAINLY THE SOUTHWEST 1/2 OF THE CWA AS MID- HIGH CLOUDS SPREAD OVERHEAD DOWNSTREAM FROM THE SOUTHWEST CONUS LOW. THERE ARE SUGGESTIONS FROM THE LATEST HRRR RUNS THAT SOME SCATTERED LOW CLOUDS COULD ALSO INCREASE MAINLY THIS AFTERNOON IN SOME AREAS NORTH OF I-80...BUT WILL KEEP IT A MOSTLY SUNNY THEME HERE AT LEAST FOR NOW. AS FOR TEMPS...FOLLOWED THE 00Z NAM/05Z RAP SOLUTION RATHER CLOSELY...WHICH RESULTED IN A 1-3 DEGREE UPWARD NUDGE FROM PREVIOUS FORECAST...NOW RANGING FROM LOW 30S FAR NORTH...MID 30S CENTRAL...LOW 40S SOUTH MAINLY KS ZONES. ITS WORTH NOTING THAT THE 06Z NAM CAME IN COLDER FOR NORTHWEST COUNTIES...BUT THIS APPEARS TO BE A RESULT OF AN OVERDONE MODEL- INITIALIZED SNOW FIELD. THAT BEING SAID...CONFIDENCE IN TEMPS ISN/T QUITE AS HIGH ESPECIALLY FOR THE ORD AREA...WHERE A LIGHT COATING OF SNOW FROM YESTERDAY ALONG WITH A WIND DIRECTION BLOWING OFF OF THE DEEPER SNOW COVER OVER THE SANDHILLS COULD WORK TO HOLD THINGS DOWN A BIT. THIS EVENING/TONIGHT...CONFIDENCE REMAINS HIGH THAT THE ENTIRE CWA REMAINS PRECIPITATION-FREE...BUT THINGS DEFINITELY START TO TURN MORE INTERESTING A FEW COUNTIES TO OUR SOUTH...AS THE AFOREMENTIONED SOUTHWESTERN CONUS MID LEVEL SHORTWAVE TROUGH STARTS CLOSING OFF A BIT AS IT HEADS EAST INTO NM. FORCING DOWNSTREAM FROM THIS WAVE WILL SPREAD DECENT CHANCES FOR AT LEAST LIGHT ACCUMULATING SNOW INTO MAINLY THE SOUTHWEST 1/4 OF KS ESPECIALLY AFTER MIDNIGHT. WHILE A CONSENSUS OF VARIOUS MODELS SUCH AS THE NAM/ECMWF/4KM WRF-NMM KEEPS ANY OF THIS SNOW AT LEAST 80 MILES SOUTH OF THE FAR SOUTHERN CWA...THE NEW 06Z GFS HAS SUDDENLY TRENDED SLIGHTLY FARTHER NORTH...BRINGING AT LEAST A DUSTING OF SNOW WITHIN ROUGHLY 20 MILES OF FAR SOUTHERN ROOKS/OSBORNE COUNTIES. FOR NOW WILL DISCOUNT THIS RUN AS A NORTHERN OUTLIER AND STAND FIRM THAT THIS SYSTEM WILL NOT BE AN ISSUE FOR OUR CWA...AND BRING ONLY A PERIOD OF PARTLY/MOSTLY CLOUDY SKIES TO MAINLY OUR SOUTHERN COUNTIES. AT THE SURFACE TONIGHT...INITIALLY FAIRLY LIGHT/VARIABLE WINDS NEAR THE RIDGE AXIS WILL TAKE ON A SLIGHTLY STEADIER SOUTHWESTERLY COMPONENT LATE IN THE NIGHT IN RESPONSE TO A SUBTLE PASSING TROUGH AXIS. GIVEN THESE LIGHT WESTERLY BREEZES AND ALSO A FAIR AMOUNT OF PASSING CLOUD ESPECIALLY SOUTH...GENERALLY RAISED LOW TEMPS 2-4 DEGREES FROM PREVIOUS GRIDS...WITH ALL BUT FAR NORTHWESTERN AREAS HOLDING UP GENERALLY 17-22. TUESDAY DAYTIME...IN A CONTINUATION FROM LATE WED NIGHT ACCUMULATING SNOW WILL CONTINUE TO OUR SOUTH...TRACKING EASTWARD MAINLY ALONG/SOUTH OF THE KS/OK BORDER...AS THE PRIMARY 500MB SHORTWAVE ENDS UP OVER SOUTHERN/WESTERN OK BY DAYS END. AGAIN THOUGH...NO LOCAL IMPACT ANTICIPATED OTHER THAN MORE MID-HIGH CLOUD OVER KS ZONES VERSUS NEB ZONES. AT THE SURFACE...HIGH PRESSURE CENTERED TO THE WEST WILL DRIVE A WESTERLY DOWNSLOPE WIND COMPONENT ACROSS THE ENTIRE CWA...AND HAVE INCREASED SUSTAINED SPEEDS CLOSER TO 15 MPH WITH HIGHER GUSTS MAINLY FOR THE NORTHERN 1/2 OF THE CWA. ASSUMING THAT SUNSHINE IS FAIRLY PLENTIFUL IN MOST AREAS...AND GIVEN SLIGHT LOW LEVEL WARMING VERSUS MONDAY...SEE LITTLE REASON WHY THIS DOWNSLOPE WIND WON/T BRING A DECENT BOOST IN HIGH TEMPS...AND HAVE RAISED HIGHS GENERALLY 2-4 DEGREES FROM PREVIOUS FORECAST...ESPECIALLY IN EASTERN AREAS FARTHEST REMOVED FROM THE WESTERN/NORTH CENTRAL NEB SNOW FIELD. THIS NOW YIELDS HIGHS IN THE MID-UPPER 40S MOST AREAS...EXCEPT LOW 40S FAR NORTHWEST. TUESDAY NIGHT...THE SOUTHERN CONUS SHORTWAVE TROUGH TREKS EAST INTO THE AR/TN AREA...HELPING TRANSITION THE FLOW OVER THE CENTRAL PLAINS TO MORE PRONOUNCED NORTHWESTERLY...BUT WITH NO IMPACTFUL DISTURBANCES. ALTHOUGH A DECENT BATCH OF MID LEVEL CLOUDS COULD SAG SOUTHWARD ACROSS THE CWA...NOT EVEN EXPECTING FLURRIES AT THIS TIME. AT THE SURFACE...A LIGHT BUT STEADY 5-10 MPH WESTERN COMPONENT SHOULD AGAIN HELP KEEP TEMPS FROM FALLING TOO FAR...AND NUDGED UP PREVIOUS LOWS VERY SLIGHTLY...KEEPING MOST PLACES UP BETWEEN 21-24 DEGREES. WEDNESDAY...DRY NORTHWESTERLY FLOW ALOFT PERSISTS...AS THE LOCAL AREA REMAINS DOWNSTREAM FROM A LOW AMPLITUDE/CLIPPER-TYPE SHORTWAVE TROUGH SLIPPING OUT OF CANADA TO THE DAKOTAS/MN BORDER AREA BY DAYS END. UNDER GENERALLY PARTLY CLOUDY SKIES...A CONTINUED DOWNSLOPE WESTERLY WIND AND WARMER AIR EVIDENT ABOVE THE SURFACE AT 850MB SHOULD CONTINUE THE WARMING TREND FROM TUESDAY...AND HAVE MADE A VERY SLIGHT UPWARD NUDGE TO PREVIOUS HIGHS WITH MOST OF THE CWA INTO THE 50-53 RANGE...EXCEPT COOLER MID-UPPER 40S MAINLY IN OUR FAR NORTH/NORTHWEST FRINGES WHERE THE SNOW FIELD COULD STILL POSSIBLY EXERT SOME INFLUENCE. THE OVERALL BIGGEST CHANCE TO WEDNESDAY INVOLVED WIND SPEEDS...WHICH WERE UPPED AT LEAST 6-8 MPH FROM PREVIOUS GRIDS INTO BREEZY TERRITORY...AND NOW EXPECT SEVERAL HOURS OF SUSTAINED WEST-NORTHWEST SPEEDS 15-20 MPH WITH SOME HIGHER GUSTS. FORTUNATELY FOR POSSIBLE FIRE WEATHER CONCERNS...RELATIVE HUMIDITY VALUES ARE FORECAST TO FALL NO LOWER THAN THE UPPER-20S PERCENT...AND THIS IS ONLY IN A SMALL PART OF KS ZONES. WEDNESDAY NIGHT...THE AFOREMENTIONED NORTHERN PLAINS CLIPPER-SYSTEM DIVES DOWN MAINLY INTO IA/WI...WHILE AT THE SURFACE THE LEADING EDGES OF A MODEST COLD FRONT WILL ENTER THE LOCAL AREA. ALTHOUGH THE ORIENTATION OF THE UPPER JET ON THE WESTERN SIDE OF THIS DISTURBANCE ALONG WITH SOME MID LEVEL RH PROGS FROM MODELS SUCH AS THE 06Z NAM SUGGEST THAT A FEW FLURRIES MIGHT NOT BE OUT OF THE QUESTION FOR PARTS OF THE CWA...WILL KEEP ALL PRECIP MENTION OUT FOR NOW WITH POSSIBLY SLIGHTLY BETTER FLURRY CHANCES HOLDING OFF UNTIL THE THURS DAYTIME HOURS. MADE VERY LITTLE CHANGE TO LOW TEMPS WITH MID-UPPER 20S ALL AREAS. LONG TERM...THURSDAY THROUGH SUNDAY...AT THE ONSET OF THE EXTENDED PERIODS...100KT TO 120KT JET H3 JET STREAKS WILL NOSE SOUTH FM ALBERTA ACROSS THE EASTERN SLOPES OF THE NORTHERN ROCKIES CARVING A TROUGH ACROSS THE EASTERN TWO THIRDS OF THE CONUS. IN A NORTHWEST FLOW REGIME ACROSS THE CENTRAL PLAINS...COLD AIR WILL BACK IN FM THE NORTHEAST WITH THE MAIN THERMAL TROUGH ORIENTED FM ONTARIO THRU THE GREAT LAKES REGION. ENERGY TRANSLATING SOUTHEAST THRU FLOW AND A PUSH OF COLD AIR SOUTH THURSDAY COULD GENERATE SNOW FLURRIES IN OUR NORTHERN ZONES. FRIDAY WILL SEE A REINFORCING SHOT OF COLD AIR AS A STRONGER JET STREAK DIVES SOUTH ALONG THE FRONT RANGE OF THE ROCKIES AND ADDITIONAL SHORTWAVE ENERGY TRANSLATES ON THE WESTERN EDGE OF THE TROUGH WHICH ULTIMATELY FURTHER DEEPENS TO THE TROUGH ACROSS CENTRAL AND EASTERN CONUS. CURRENTLY HAVE FLURRIES IN THE FORECAST ON FRIDAY AND THIS IS STILL WARRANTED WITH FROPA/UPPER DYNAMICS. TEMPS WILL TREND COLDER THURSDAY...CLOSER TO SEASONAL NORMALS...AND WILL DROP FURTHER FRIDAY WITH STRONGER COLD FRONT. A COLD SURFACE HIGH PRESSURE SYSTEM WILL SETTLE ACROSS THE CENTRAL PLAINS BEHIND THE FRONT FRIDAY NIGHT...WHICH WILL RESULT IN TEMPS IN THE TEENS FOR LOWS. AFTER A COLD COUPLE OF DAYS FOR THE END OF THE WORKWEEK...THE WEATHER OVER THE WEEKEND TRENDS WARMER. THE SFC RIDGE AXIS SLIDES SOUTHEAST ON SATURDAY...ALLOWING FOR RETURN FLOW...AND ALOFT...THE UPPER TROUGH DEPARTS EASTWARD AND HEIGHTS BEGIN TO RISE ACROSS THE CENTRAL PLAINS. BY SUNDAY THE RIDGE WHICH WAS OVER THE ROCKIES SATURDAY REACHES THE INTERIOR CONUS..AND WARMER AIR SPREADS EASTWARD. SUNDAY IS LOOKING LIKE THE WARMEST OF THE EXTENDED PERIODS WITH HIGHS IN THE 40S FOR THE MOST PART AND 50S MAY NOT BE OUT OF THE QUESTION. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...PFANNKUCH LONG TERM/AVIATION...FAY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
433 AM CST MON FEB 11 2013 .SHORT TERM...THROUGH WEDNESDAY NIGHT. COMPARED TO THE PAST FEW DAYS...THESE NEXT 72 HOURS ARE LOOKING FAIRLY BENIGN WITH ESSENTIALLY ZERO RISK OF PRECIPITATION. HOWEVER...BOTH TUESDAY AND ESPECIALLY WEDNESDAY ARE TRENDING A BIT BREEZIER THAN PREVIOUSLY ADVERTISED...BUT ALSO A BIT WARMER AS WELL. 09Z OBJECTIVE SURFACE ANALYSIS PLACED THE CENTER OF THE DEPARTING...STRONG 991MB LOW OVER CENTRAL WI...WITH THE CENTRAL PLAINS CAUGHT WITHIN THE BACKSIDE OF THE TIGHT PRESSURE GRADIENT BETWEEN THIS LOW AND A ROUGHLY 1024MB HIGH OVER WY. A FAIRLY PRONOUNCED GRADIENT IN WIND SPEEDS IS EVIDENT ACROSS THE CWA AT THIS TIME...WITH NORTHWESTERLY SPEEDS AVERAGING NO MORE THAN 10-15 MPH IN SOUTHWEST AREAS...WHILE MOST CENTRAL/NORTHEAST AREAS CONTINUE TO REPORT SUSTAINED SPEEDS AT LEAST 15-20 MPH WITH GUSTS UP TO NEAR 30 MPH. FORTUNATELY THOUGH...SPEEDS HAVE FINALLY EASED WELL BELOW ADVISORY CRITERIA...WHICH TOOK A FEW HOURS LONGER EARLIER TONIGHT THAN ORIGINALLY THOUGHT. ANY LINGERING FLURRIES FROM EARLIER TONIGHT HAVE ALSO DEPARTED TO THE NORTHEAST...WITH IN FACT NEARLY FULLY CLEAR SKIES NOW OVER ALL BUT THE FAR EASTERN EDGES OF THE CWA WHERE SOME LOW STRATUS LINGERS. PRE-DAWN TEMPERATURES ARE FAIRLY UNIFORM ACROSS THE CWA...WITH MOST AREAS LIKELY HEADING FOR LOWS SOMEWHERE BETWEEN 21-27. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA CONFIRMED AN ACTIVE PATTERN ACROSS THE CONUS...WITH THE NEARLY VERTICALLY STACKED CLOSED LOW DEPARTING OVER THE WI AREA...WHILE OFF TO OUR SOUTHWEST...A CURRENTLY OPEN 500MB SHORTWAVE TROUGH WAS CENTERED NEAR THE CA/NV/UT/AZ BORDERS...WITH ONLY THE SLIGHTEST HINT OF SHORTWAVE RIDGING OVER THE CENTRAL HIGH PLAINS IN BETWEEN THESE TWO PRIMARY LOWS. FORECAST-WISE TODAY...WHILE BY NO MEANS AS WINDY AS YESTERDAY...A HEALTHY NORTHWEST BREEZE OF 15-20 MPH WITH GUSTS 25+ MPH WILL PERSIST WELL INTO THE EARLY-MID AFTERNOON HOURS ACROSS ROUGHLY THE NORTHEAST 1/2 OF THE CWA THANKS TO EFFICIENT MIXING TO AROUND 850MB...BEFORE EASING MORE NOTICEABLY BETWEEN 3 PM AND SUNSET. ANY LINGERING/PRESUMABLY MINOR BLOWING SNOW ISSUES IN THE ORD AREA SHOULD CONTINUE TO ABATE WITH TIME. WIND SPEEDS ACROSS ROUGHLY THE SOUTHWEST 1/2 OF THE AREA WILL AVERAGE AT LEAST 5 MPH LIGHTER...AND ALSO START TO EASE UP SOONER ESPECIALLY THIS AFTERNOON AS A BROAD 1025MB RIDGE AXIS SETTLES INTO THE AREA. CLOUD-WISE...WHILE NEARLY THE ENTIRE AREA WILL START OUT WITH PLENTY OF SUNSHINE...THE AFTERNOON HOURS WILL BRING AT LEAST PARTLY CLOUDY SKIES TO MAINLY THE SOUTHWEST 1/2 OF THE CWA AS MID- HIGH CLOUDS SPREAD OVERHEAD DOWNSTREAM FROM THE SOUTHWEST CONUS LOW. THERE ARE SUGGESTIONS FROM THE LATEST HRRR RUNS THAT SOME SCATTERED LOW CLOUDS COULD ALSO INCREASE MAINLY THIS AFTERNOON IN SOME AREAS NORTH OF I-80...BUT WILL KEEP IT A MOSTLY SUNNY THEME HERE AT LEAST FOR NOW. AS FOR TEMPS...FOLLOWED THE 00Z NAM/05Z RAP SOLUTION RATHER CLOSELY...WHICH RESULTED IN A 1-3 DEGREE UPWARD NUDGE FROM PREVIOUS FORECAST...NOW RANGING FROM LOW 30S FAR NORTH...MID 30S CENTRAL...LOW 40S SOUTH MAINLY KS ZONES. ITS WORTH NOTING THAT THE 06Z NAM CAME IN COLDER FOR NORTHWEST COUNTIES...BUT THIS APPEARS TO BE A RESULT OF AN OVERDONE MODEL- INITIALIZED SNOW FIELD. THAT BEING SAID...CONFIDENCE IN TEMPS ISN/T QUITE AS HIGH ESPECIALLY FOR THE ORD AREA...WHERE A LIGHT COATING OF SNOW FROM YESTERDAY ALONG WITH A WIND DIRECTION BLOWING OFF OF THE DEEPER SNOW COVER OVER THE SANDHILLS COULD WORK TO HOLD THINGS DOWN A BIT. THIS EVENING/TONIGHT...CONFIDENCE REMAINS HIGH THAT THE ENTIRE CWA REMAINS PRECIPITATION-FREE...BUT THINGS DEFINITELY START TO TURN MORE INTERESTING A FEW COUNTIES TO OUR SOUTH...AS THE AFOREMENTIONED SOUTHWESTERN CONUS MID LEVEL SHORTWAVE TROUGH STARTS CLOSING OFF A BIT AS IT HEADS EAST INTO NM. FORCING DOWNSTREAM FROM THIS WAVE WILL SPREAD DECENT CHANCES FOR AT LEAST LIGHT ACCUMULATING SNOW INTO MAINLY THE SOUTHWEST 1/4 OF KS ESPECIALLY AFTER MIDNIGHT. WHILE A CONSENSUS OF VARIOUS MODELS SUCH AS THE NAM/ECMWF/4KM WRF-NMM KEEPS ANY OF THIS SNOW AT LEAST 80 MILES SOUTH OF THE FAR SOUTHERN CWA...THE NEW 06Z GFS HAS SUDDENLY TRENDED SLIGHTLY FARTHER NORTH...BRINGING AT LEAST A DUSTING OF SNOW WITHIN ROUGHLY 20 MILES OF FAR SOUTHERN ROOKS/OSBORNE COUNTIES. FOR NOW WILL DISCOUNT THIS RUN AS A NORTHERN OUTLIER AND STAND FIRM THAT THIS SYSTEM WILL NOT BE AN ISSUE FOR OUR CWA...AND BRING ONLY A PERIOD OF PARTLY/MOSTLY CLOUDY SKIES TO MAINLY OUR SOUTHERN COUNTIES. AT THE SURFACE TONIGHT...INITIALLY FAIRLY LIGHT/VARIABLE WINDS NEAR THE RIDGE AXIS WILL TAKE ON A SLIGHTLY STEADIER SOUTHWESTERLY COMPONENT LATE IN THE NIGHT IN RESPONSE TO A SUBTLE PASSING TROUGH AXIS. GIVEN THESE LIGHT WESTERLY BREEZES AND ALSO A FAIR AMOUNT OF PASSING CLOUD ESPECIALLY SOUTH...GENERALLY RAISED LOW TEMPS 2-4 DEGREES FROM PREVIOUS GRIDS...WITH ALL BUT FAR NORTHWESTERN AREAS HOLDING UP GENERALLY 17-22. TUESDAY DAYTIME...IN A CONTINUATION FROM LATE WED NIGHT ACCUMULATING SNOW WILL CONTINUE TO OUR SOUTH...TRACKING EASTWARD MAINLY ALONG/SOUTH OF THE KS/OK BORDER...AS THE PRIMARY 500MB SHORTWAVE ENDS UP OVER SOUTHERN/WESTERN OK BY DAYS END. AGAIN THOUGH...NO LOCAL IMPACT ANTICIPATED OTHER THAN MORE MID-HIGH CLOUD OVER KS ZONES VERSUS NEB ZONES. AT THE SURFACE...HIGH PRESSURE CENTERED TO THE WEST WILL DRIVE A WESTERLY DOWNSLOPE WIND COMPONENT ACROSS THE ENTIRE CWA...AND HAVE INCREASED SUSTAINED SPEEDS CLOSER TO 15 MPH WITH HIGHER GUSTS MAINLY FOR THE NORTHERN 1/2 OF THE CWA. ASSUMING THAT SUNSHINE IS FAIRLY PLENTIFUL IN MOST AREAS...AND GIVEN SLIGHT LOW LEVEL WARMING VERSUS MONDAY...SEE LITTLE REASON WHY THIS DOWNSLOPE WIND WON/T BRING A DECENT BOOST IN HIGH TEMPS...AND HAVE RAISED HIGHS GENERALLY 2-4 DEGREES FROM PREVIOUS FORECAST...ESPECIALLY IN EASTERN AREAS FARTHEST REMOVED FROM THE WESTERN/NORTH CENTRAL NEB SNOW FIELD. THIS NOW YIELDS HIGHS IN THE MID-UPPER 40S MOST AREAS...EXCEPT LOW 40S FAR NORTHWEST. TUESDAY NIGHT...THE SOUTHERN CONUS SHORTWAVE TROUGH TREKS EAST INTO THE AR/TN AREA...HELPING TRANSITION THE FLOW OVER THE CENTRAL PLAINS TO MORE PRONOUNCED NORTHWESTERLY...BUT WITH NO IMPACTFUL DISTURBANCES. ALTHOUGH A DECENT BATCH OF MID LEVEL CLOUDS COULD SAG SOUTHWARD ACROSS THE CWA...NOT EVEN EXPECTING FLURRIES AT THIS TIME. AT THE SURFACE...A LIGHT BUT STEADY 5-10 MPH WESTERN COMPONENT SHOULD AGAIN HELP KEEP TEMPS FROM FALLING TOO FAR...AND NUDGED UP PREVIOUS LOWS VERY SLIGHTLY...KEEPING MOST PLACES UP BETWEEN 21-24 DEGREES. WEDNESDAY...DRY NORTHWESTERLY FLOW ALOFT PERSISTS...AS THE LOCAL AREA REMAINS DOWNSTREAM FROM A LOW AMPLITUDE/CLIPPER-TYPE SHORTWAVE TROUGH SLIPPING OUT OF CANADA TO THE DAKOTAS/MN BORDER AREA BY DAYS END. UNDER GENERALLY PARTLY CLOUDY SKIES...A CONTINUED DOWNSLOPE WESTERLY WIND AND WARMER AIR EVIDENT ABOVE THE SURFACE AT 850MB SHOULD CONTINUE THE WARMING TREND FROM TUESDAY...AND HAVE MADE A VERY SLIGHT UPWARD NUDGE TO PREVIOUS HIGHS WITH MOST OF THE CWA INTO THE 50-53 RANGE...EXCEPT COOLER MID-UPPER 40S MAINLY IN OUR FAR NORTH/NORTHWEST FRINGES WHERE THE SNOW FIELD COULD STILL POSSIBLY EXERT SOME INFLUENCE. THE OVERALL BIGGEST CHANCE TO WEDNESDAY INVOLVED WIND SPEEDS...WHICH WERE UPPED AT LEAST 6-8 MPH FROM PREVIOUS GRIDS INTO BREEZY TERRITORY...AND NOW EXPECT SEVERAL HOURS OF SUSTAINED WEST-NORTHWEST SPEEDS 15-20 MPH WITH SOME HIGHER GUSTS. FORTUNATELY FOR POSSIBLE FIRE WEATHER CONCERNS...RELATIVE HUMIDITY VALUES ARE FORECAST TO FALL NO LOWER THAN THE UPPER-20S PERCENT...AND THIS IS ONLY IN A SMALL PART OF KS ZONES. WEDNESDAY NIGHT...THE AFOREMENTIONED NORTHERN PLAINS CLIPPER-SYSTEM DIVES DOWN MAINLY INTO IA/WI...WHILE AT THE SURFACE THE LEADING EDGES OF A MODEST COLD FRONT WILL ENTER THE LOCAL AREA. ALTHOUGH THE ORIENTATION OF THE UPPER JET ON THE WESTERN SIDE OF THIS DISTURBANCE ALONG WITH SOME MID LEVEL RH PROGS FROM MODELS SUCH AS THE 06Z NAM SUGGEST THAT A FEW FLURRIES MIGHT NOT BE OUT OF THE QUESTION FOR PARTS OF THE CWA...WILL KEEP ALL PRECIP MENTION OUT FOR NOW WITH POSSIBLY SLIGHTLY BETTER FLURRY CHANCES HOLDING OFF UNTIL THE THURS DAYTIME HOURS. MADE VERY LITTLE CHANGE TO LOW TEMPS WITH MID-UPPER 20S ALL AREAS. .LONG TERM...THURSDAY THROUGH SUNDAY...AT THE ONSET OF THE EXTENDED PERIODS...100KT TO 120KT JET H3 JET STREAKS WILL NOSE SOUTH FM ALBERTA ACROSS THE EASTERN SLOPES OF THE NORTHERN ROCKIES CARVING A TROUGH ACROSS THE EASTERN TWO THIRDS OF THE CONUS. IN A NORTHWEST FLOW REGIME ACROSS THE CENTRAL PLAINS...COLD AIR WILL BACK IN FM THE NORTHEAST WITH THE MAIN THERMAL TROUGH ORIENTED FM ONTARIO THRU THE GREAT LAKES REGION. ENERGY TRANSLATING SOUTHEAST THRU FLOW AND A PUSH OF COLD AIR SOUTH THURSDAY COULD GENERATE SNOW FLURRIES IN OUR NORTHERN ZONES. FRIDAY WILL SEE A REINFORCING SHOT OF COLD AIR AS A STRONGER JET STREAK DIVES SOUTH ALONG THE FRONT RANGE OF THE ROCKIES AND ADDITIONAL SHORTWAVE ENERGY TRANSLATES ON THE WESTERN EDGE OF THE TROUGH WHICH ULTIMATELY FURTHER DEEPENS TO THE TROUGH ACROSS CENTRAL AND EASTERN CONUS. CURRENTLY HAVE FLURRIES IN THE FORECAST ON FRIDAY AND THIS IS STILL WARRANTED WITH FROPA/UPPER DYNAMICS. TEMPS WILL TREND COLDER THURSDAY...CLOSER TO SEASONAL NORMALS...AND WILL DROP FURTHER FRIDAY WITH STRONGER COLD FRONT. A COLD SURFACE HIGH PRESSURE SYSTEM WILL SETTLE ACROSS THE CENTRAL PLAINS BEHIND THE FRONT FRIDAY NIGHT...WHICH WILL RESULT IN TEMPS IN THE TEENS FOR LOWS. AFTER A COLD COUPLE OF DAYS FOR THE END OF THE WORKWEEK...THE WEATHER OVER THE WEEKEND TRENDS WARMER. THE SFC RIDGE AXIS SLIDES SOUTHEAST ON SATURDAY...ALLOWING FOR RETURN FLOW...AND ALOFT...THE UPPER TROUGH DEPARTS EASTWARD AND HEIGHTS BEGIN TO RISE ACROSS THE CENTRAL PLAINS. BY SUNDAY THE RIDGE WHICH WAS OVER THE ROCKIES SATURDAY REACHES THE INTERIOR CONUS..AND WARMER AIR SPREADS EASTWARD. SUNDAY IS LOOKING LIKE THE WARMEST OF THE EXTENDED PERIODS WITH HIGHS IN THE 40S FOR THE MOST PART AND 50S MAY NOT BE OUT OF THE QUESTION. && .PREV DISCUSSION... /ISSUED 1050 PM CST SUN FEB 10 2013/ AVIATION...06Z KGRI TAF. STRONG NORTHWEST WIND WILL BE THE PRIMARY CONCERN FOR THE FIRST SEVERAL HOURS OF THE FORECAST...THEN SUBSIDE SOMEWHAT BY SUNRISE...BUT CONTINUE TO BE BRISK INTO MONDAY. CEILINGS WILL BE SCATTERING AND COULD FLUCTUATE BETWEEN VFR AND MVFR CEILING FOR THE FIRST HOUR OR TWO AS AN AREA OF LOW PRESSURE CONTINUES TO PULL NORTHEAST...BUT SHOULD BE PRIMARILY WITHOUT A CEILING FROM THE GET GO. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...PFANNKUCH LONG TERM...FAY AVIATION...HEINLEIN
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1140 PM CST SUN FEB 10 2013 .UPDATE... .DISCUSSION... SATELLITE...SFC OBS...RADAR AND A REPORTS FROM LAW ENFORCEMENT SUGGEST BLIZZARD CONDITIONS WILL CONTINUE FOR A FEW MORE HOURS ACROSS THE NORTHEAST CORNER OF THE FCST AREA. THE RUC SHOWS THE LOW LEVEL CLOUD EXITING THE FCST BY AROUND 10Z OR SO. THIS SHOULD ALLOW FOR LESS VERTICAL MIXING AND SLOWER WIND SPEEDS. A WINTER WEATHER ADVISORY CONTINUES OVERNIGHT FOR ALL AREAS AFFECTED BY THE BLIZZARD. STRONG WINDS IN SOME AREAS WILL CONTINUE TO BUILD DRIFTS AND PRODUCE NEAR WHITE OUT CONDITIONS IN SPOTS. IN OTHER AREAS...SOME RURAL UNIMPROVED ROADS ARE PARTIALLY OR COMPLETELY BLOCKED BY HARD PACKED DRIFTS. && .PREV DISCUSSION... /ISSUED 1107 PM CST SUN FEB 10 2013/ UPDATE... AVIATION... FLIGHT CONDITIONS ACROSS NCNTL NEB EAST OF KVTN WILL GRADUALLY IMPROVE FROM IFR TO VFR AS LOW CLOUDINESS EXIT EAST OVERNIGHT. VFR IS EXPECTED ALL AREAS BY 12Z. VFR IS EXPECTED ALL AREAS THEREAFTER THROUGH 06Z MONDAY EVENING. PREV DISCUSSION... /ISSUED 923 PM CST SUN FEB 10 2013/ UPDATE... DISCUSSION... BLIZZARD CONDITIONS HAVE DECREASED WEST OF THEDFORD AND CODY. A WINTER WEATHER ADVISORY FOR BLOWING SNOW IS NOW IN EFFECT UNTIL 8 AM CST. TRAVEL ON UNIMPROVED ROADS WILL REMAIN HAZARDOUS OVERNIGHT DUE TO DEEP DRIFTS PARTIALLY OR COMPLETELY BLOCKING SOME ROADS. THESE DRIFTS WILL CONTINUE TO BUILD OVERNIGHT IN SOME AREAS AS WINDS LOCALLY CONTINUE AT SPEEDS UP TO 25 MPH. PREV DISCUSSION... /ISSUED 717 PM CST SUN FEB 10 2013/ UPDATE... DISCUSSION... A QUICK FIX TO INCREASE WIND SPEEDS IN THE BLIZZARD WARNED AREA. FCST WINDS SHOULD BE CLOSER TO THE OBSERVED SPEEDS WITH THIS UPDATE. PREV DISCUSSION... /ISSUED 705 PM CST SUN FEB 10 2013/ UPDATE... DISCUSSION... SKIES HAVE CLEARED SUFFICIENTLY FOR WIND SPEEDS TO DECREASE WELL BELOW 30 MPH ACROSS SOUTHWEST NEBRASKA WHERE THE WIND ADVISORY WAS FLYING. THE WIND ADVISORY IS CANCELLED. NORTHWEST WINDS OF 15 TO 25 MPH ARE EXPECTED THE REST OF TONIGHT. PREV DISCUSSION... /ISSUED 520 PM CST SUN FEB 10 2013/ UPDATE... AVIATION... VFR IS EXPECTED TO CONTINUE SPREADING EAST THROUGH THE FCST AREA THIS EVENING. SIGNIFICANT WRAP AROUND SNOW AND LOW CIGS MAY CONTINUE AROUND KONL UNTIL AROUND MIDNIGHT...PERHAPS A FEW HOURS LATER WITH WINDS REMAINING STRONG. WINDS IN THE VFR AREA WILL DECREASE SUBSTANTIALLY AT SUNSET WHILE ANY AREAS WITH MVFR WILL SEE STRONG WINDS CONTINUING. VFR IS EXPECTED ALL AREAS MONDAY. PREV DISCUSSION... /ISSUED 351 PM CST SUN FEB 10 2013/ SYNOPSIS... INTENSE LOW PRESSURE WAS LOCATED WEST OF SIOUX CITY IOWA THIS AFTERNOON WITH VERY STRONG NORTHWESTERLY WINDS PRESENT ACROSS ALL OF WESTERN AND NORTH CENTRAL NEBRASKA. WIND GUSTS WERE ON THE ORDER OF 40 TO 55 MPH THIS AFTERNOON. WITH SNOW CONTINUING IN THE CENTRAL AND NORTHERN SANDHILLS...AS WELL AS NORTH CENTRAL NEBRASKA...BLIZZARD OR NEAR BLIZZARD CONDITIONS CONTINUE TO PERSIST ATTM. SNOWFALL ACROSS SOUTHWESTERN NEBRASKA HAS DIMINISHED OVER THE PAST COUPLE OF HOURS...HOWEVER...SOME BLOWING SNOW ISSUES CONTINUE...WITH GROUND BLIZZARD CONDITIONS CONTINUING IN KEITH AND GARDEN COUNTIES. ELSEWHERE...ACROSS SOUTHWESTERN NEBRASKA...VSBYS WERE IN THE 1 TO 3 MILE RANGE. A PLETHORA OF WINTER HEADLINES CONTINUE ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...AND THESE WILL BE EVALUATED NEAR FCST ISSUANCE. SHORT TERM...(THIS EVENING THROUGH MONDAY) 990 MB SFC LOW PRESSURE CENTER IS LOCATED IN NORTHWEST IOWA AND CONTINUES TO MOVE EAST NORTHEAST AWAY FROM THE AREA. PEAK WINDS ARE OCCURRING NOW AND SHOULD BEGIN TO SLOWLY DIMINISH THROUGH THE EVENING. TRAFFIC CAMS AND CALLS TO AND FROM LAW ENFORCEMENT OFFICIALS AROUND THE REGION INDICATE THAT THE BLIZZARD WARNING CAN BE DOWNGRADED TO A WINTER WEATHER ADVISORY ACROSS THE SOUTHERN TIER...INCLUDING THE INTERSTATE CORRIDOR. WILL KEEP IT GOING ACROSS NORTHERN NEBRASKA AND THE SANDHILLS...WHERE THEY ARE STILL EXPERIENCING SOME LIGHT FALLING SNOW AND POOR VISIBILITY...DOWN TO 200 YARDS IN SOME CASES. SNOWFALL TOTALS RANGED FROM 4 TO 10 INCHES...ABOUT WHAT WAS FORECASTED. PEAK WIND SPEEDS OF 57 MPH ALSO OCCURED. CONDTITONS SHOULD GRADUALLY IMPROVE FROM WEST TO EAST THROGH THE NIGHT. MONDAY SHOULD SEE WINDS CONTINUE TO DIMINISH AND SKIES CLEAR...BUT HIGH TEMPERATURES WILL BE CHILLY IN THE UPPER 20S TO MID 30S. LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) MAIN FORECAST CHALLENGES DEAL WITH TEMPERATURES AND THE POSSIBILITY OF LIGHT SNOW THURSDAY INTO FRIDAY. LIGHT WESTERLY WINDS...FRESH SNOW COVER AND MOSTLY CLEAR SKIES MONDAY NIGHT...WILL SET THE STAGE FOR COLD TEMPERATURES TUESDAY MORNING. UNDERCUT GUIDANCE ACROSS SNOW COVERED AREAS...AND WENT WITH LOWS NEAR ZERO IN THE PLATTE RIVER VALLEY. ON TUESDAY...AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL SLIDE EAST ACROSS THE SRN PLAINS. PRECIPITATION AND CLOUDS ARE EXPECTED TO REMAIN SOUTH OF THE FORECAST AREA. EVEN WITH FULL SUN...TEMPS WILL STRUGGLE TO GET OUT OF THE HIGH 30S WITH LIGHT WINDS...SNOW COVER...AND H85 TEMPS OF -2 TO -4 C. TEMPERATURES TUESDAY...WILL APPROACH THE LOWER 40S IN ADVANCE OF AN APPROACHING CLIPPER SYSTEM...WHICH WILL ARRIVE ON WEDNESDAY NIGHT. WINDY AND COLDER TEMPERATURES ARRIVE ON THURSDAY AS A CLIPPER TRAVERSES THE EASTERN DAKOTAS AND UPPER MISSISSIPPI VALLEY. THE MEX AND ECE GUIDANCE FEATURES A WIDE SPREAD IN TEMPS WITH LOWER 30S NORTHEAST TO THE MIDDLE 40S IN THE SOUTHWEST. DECIDED TO UNDERCUT THESE NUMBERS BASED ON FCST H85 TEMPS AND RESIDUAL SNOW COVER. COLDER TEMPERATURES WILL PUSH INTO THE REGION ON FRIDAY AS ARCTIC HIGH PRESSURE BUILDS INTO NORTHEASTERN NEBRASKA. HIGHS FRIDAY WILL BE IN THE 20S TO THE LOWER 30S OVER FAR SOUTHWESTERN NEBRASKA. ON SATURDAY AND SUNDAY...RIDGING WILL BEGIN TO BUILD EAST INTO THE CENTRAL CONUS...AS A TROUGH OF LOW PRESSURE PUSHES INTO FAR WESTERN CANADA AND THE NWRN CONUS. MORE SEASONAL HIGHS ARE FORECAST SATURDAY AND SUNDAY WITH READINGS IN THE 40S EXPECTED. AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) BLOWING SNOW WILL CONTINUE THROUGH THE LATE AFTERNOON AND EARLY EVENING HOURS AT THE KLBF TERMINAL...AND THROUGH LATE EVENING AT THE KVTN TERMINAL...WITH VSBYS OF 3 TO 5 SM AT THE KLBF TERMINAL...AND PERIODIC VSBYS DOWN TO 1/2 SM AT THE KVTN TERMINAL. WINDS ARE EXPECTED TO DIMINISH AFTER 03Z TONIGHT AT THE KLBF TERMINAL AND AFTER 06Z FOR THE KVTN TERMINAL. IN THE MEANTIME...NORTHWESTERLY WINDS SUSTAINED AT 30 KTS...WITH GUSTS OVER 40 KTS WILL BE LIKELY ACROSS ALL OF WESTERN AND NORTH CENTRAL NEBRASKA THROUGH EARLY THIS EVENING. CIGS WILL RANGE FROM 1000 TO 4000 FT AGL THROUGH LATE THIS AFTERNOON. CIGS WILL LIFT TO ABOVE 12000 FT AGL AT THE KLBF TERMINAL BY LATE EVENING...AND TOWARD SUNRISE MONDAY AT THE KVTN TERMINAL. && .LBF WATCHES/WARNINGS/ADVISORIES...WINTER WEATHER ADVISORY UNTIL 8 AM CST /7 AM MST/ MONDAY FOR NEZ004-005-008-022>029-035>038-056-057-059-094. BLIZZARD WARNING UNTIL 4 AM CST MONDAY FOR NEZ006-007-009-010. && $$ SHORT TERM...CDC LONG TERM...BROOKS AVIATION....CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1050 PM CST SUN FEB 10 2013 .UPDATE...UPDATED THE FORECAST FOR THE EXPIRATION OF THE WIND AND WINTER WEATHER ADVISORIES AS WIND HAS GENERALLY DECREASED SOME...BUT WE COULD GET SOME HEALTHY GUSTS WELL INTO THE OVERNIGHT. TWEAKED UP HOURLY TEMPERATURES A BIT WITH THE INCREASED WIND SPEED AND ALSO ADDED SOME FLURRIES OVER THE NORTHEASTERN THIRD FOR THE OVERNIGHT AS THE MOSAIC RADAR LOOP INDICATES. && .AVIATION...06Z KGRI TAF. STRONG NORTHWEST WIND WILL BE THE PRIMARY CONCERN FOR THE FIRST SEVERAL HOURS OF THE FORECAST...THEN SUBSIDE SOMEWHAT BY SUNRISE...BUT CONTINUE TO BE BRISK INTO MONDAY. CEILINGS WILL BE SCATTERING AND COULD FLUCTUATE BETWEEN VFR AND MVFR CEILING FOR THE FIRST HOUR OR TWO AS AN AREA OF LOW PRESSURE CONTINUES TO PULL NORTHEAST...BUT SHOULD BE PRIMARILY WITHOUT A CEILING FROM THE GET GO. && PREV DISCUSSION... /ISSUED 259 PM CST SUN FEB 10 2013/ SHORT TERM...TODAY THROUGH MONDAY NIGHT. MAIN CONCERN DURING THIS TIME PERIOD WILL BE THE WINDS BEHIND THE SURFACE LOW. OUR NORTHERN COUNTIES...WHERE SNOWFALL OCCURRED EARLIER TODAY...WILL LIKELY RUN INTO VISIBILITY RESTRICTIONS AS BLOWING SNOW OCCURS THROUGH THE EARLY EVENING HOURS. ORD HAS EXPERIENCED VISIBILITIES BETWEEN ONE AND TWO MILES SINCE ABOUT 18Z TODAY...BUT EARLIER TODAY CONDITIONS WERE BELOW HALF A MILE. ALSO...THERE WILL BE A SLIGHT CHANCE FOR SNOW THROUGH THE REMAINDER OF TODAY...MAINLY FOR OUR NORTHERN COUNTIES. AT 20Z...THE RAP INDICATED A 500MB LOW APPROXIMATELY CENTERED OVER SIOUX FALLS SOUTH DAKOTA. THE SURFACE LOW WAS DIRECTLY UNDER THE UPPER LEVEL LOW...RESULTING IN A STACKED TROUGH WHICH IS NOW EXITING THE CENTRAL PLAINS. BEHIND THE SURFACE LOW...HEIGHT RISES ARE RESULTING IN A SHARP PRESSURE GRADIENT OVER THE OUTLOOK AREA. NORTHWESTERLY WIND SPEEDS OF 30 MPH WERE EXPERIENCED OVER NEARLY THE ENTIRE CWA. GUSTS WERE REACHING THE MID TO UPPER 40S...WITH ONLY A COUPLE SITES REACHING 50 MPH. THE WINTER WEATHER ADVISORY FOR BLOWING SNOW WILL CONTINUE UNTIL 9 PM TONIGHT TONIGHT. THIS WILL LIKELY NEED TO BE CONVERTED TO A WIND ADVISORY IF VISIBILITIES RECOVERY LATER TODAY. THE WIND ADVISORY COUNTIES UNTIL 9 PM...AS MODELS ARE NOT DEPICTING ANY LETTING UP OF THE PRESSURE GRADIENT BEFORE THEN. THE WIND ADVISORY MAY NEED TO BE EXTENDED FOR OUR EASTERN COUNTIES IF CONDITIONS DO NO EASE UP LATER TONIGHT. WIND SPEEDS WILL BEGIN TO RELAX AFTER MIDNIGHT AS THE PRESSURE GRADIENT EASES OVER THE REGION. A NORTHWESTERLY WIND COMPONENT WILL BE REALIZED OVER THE ENTIRE SHORT TERM PERIOD. HIGH TEMPERATURES FOR TOMORROW WILL BE RELATIVELY CLOSE TO NORMAL FOR THIS TIME OF YEAR. ON THE OTHER HAND...LOW TEMPERATURES WILL BE SLIGHTLY ABOVE NORMAL FOR THIS TIME OF YEAR. LONG TERM...MONDAY NIGHT THROUGH SUNDAY...WEAK ZONAL FLOW IS EXPECTED ACROSS THE REGION TO BEGIN THE EXTENDED PERIODS AS THE VIGOROUS UPPER LEVEL LOW THAT MOVED ACROSS THE LOCAL AREA THIS MORNING APPROACHES THE EASTERN SEABOARD AND A SECOND UPPER LEVEL LOW TRACKS ACROSS THE DESERT SOUTHWEST. AT THE SAME TIME A WEAK UPPER LEVEL SHORTWAVE IS EXPECTED TO EXTEND ACROSS THE LOCAL AREA FROM THE NORTH...PROVIDING AMPLE MID LEVEL CLOUD COVER DURING THE OVERNIGHT HOURS MONDAY INTO TUESDAY MORNING...BUT WITH MINIMAL FORCING AND VERY LIMITED LOW LEVEL MOISTURE...DO NO EXPECT ANY SORT OF PRECIPITATION UNDER THIS SCENARIO. AS THE AFOREMENTIONED UPPER LEVEL ACROSS THE DESERT SOUTHWEST MOVES INTO THE SOUTHERN PLAINS TUESDAY AFTERNOON...THE UPPER LEVEL FLOW PATTERN WILL BECOME MORE AMPLIFIED...AS A RIDGE OF HIGH PRESSURE WORKS ITS WAY TOWARDS THE WEST COAST. THIS WILL ESTABLISH A NORTHWESTERLY FLOW ALOFT ACROSS THE NORTHERN AND CENTRAL PLAINS BY WEDNESDAY...WITH MULTIPLE QUICK PASSING UPPER LEVEL DISTURBANCES EXPECTED TO TRAVERSE THE PLAINS. WITH THE QUICK MOVING NATURE OF THESE DISTURBANCES AND DRY LOW LEVELS OF THE ATMOSPHERE...DO NOT THINK MORE THAN FLURRIES WILL BE REALIZED THROUGH THE END OF THE WEEK...WITH THE BEST GUEST AT TIMING BEING DURING THE DAY ACROSS THE NORTHWEST THURSDAY...AND ACROSS ALL AREAS ON FRIDAY. THE FIRST OF THESE DISTURBANCE WILL BE ACCOMPANIED BY A SURFACE COLD FRONT...WHICH IS EXPECTED TO KNOCK TEMPERATURES DOWN 10+ DEGREES F ON THURSDAY...WITH THIS COOLER...YET SEASONAL AIRMASS THEN EXPECTED TO PERSIST ACROSS THE LOCAL ARE THROUGH THE END OF THE WEEK. AHEAD OF THE FRONT...WEDNESDAY AFTERNOON APPEARS TO BE THE NICEST DAY OF THE WEEK...WITH A LIGHT DOWNSLOPING COMPONENT TO THE WINDS LIKELY HELPING TEMPERATURES CLIMB TO NEAR 50 DEGREES. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE/AVIATION...HEINLEIN
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
457 AM MST MON FEB 11 2013 .AVIATION... 12Z TAF CYCLE A CHALLENGING DAY LIKELY FOR AVIATION AS TWO SURFACE FRONTS AND AN UPPER LEVEL LOW CONVERGE OVER THE AREA. CONFIDENCE ON THE TIMING OF THE MAIN IMPACT FEATURES IS MODERATE AS VARIOUS SHORT-TERM MODEL GUIDANCE IS STILL CONFLICTING. THE LATEST RUC AND HRRR SUGGEST A RATHER POTENT SNOW BAND WILL SLIDE EAST TODAY MUCH EARLIER THAN THE MET/MAV MOS GUIDANCE...SO HAVE DECIDED TO BRING IN THE FEATURE OVER CENTRAL NM FOR KABQ/KSAF FASTER THAN PREVIOUS TAFS. POTENTIAL FOR A SHORT DURATION OF IFR IS HIGH FOR SITES THAT ARE IMPACTED BY THIS BAND. WINDS WILL SHIFT DRAMATICALLY TO THE WEST AND NW WITH THIS FRONT...THEN DIMINISH DURING THE EVENING WHILE -SHSN LINGER OVER CENTRAL/WESTERN NM. MEANWHILE ACROSS THE EAST RETURN EASTERLY FLOW WILL INCREASE MOISTURE AND LOWER MID LEVEL CLOUD DECKS AFT 00Z. MODERATE TO LCL HEAVY SN IS EXPECTED AFT SUNSET WITH MUCH LONGER DURATION IMPACTS FOR KLVS/KTCC OVERNIGHT. GUYER && .PREV DISCUSSION...338 AM MST MON FEB 11 2013... AN UPPER TROUGH THAT DUG DEEPLY THROUGH UT ON SUNDAY APPEARS TO BE FORMING A CLOSED LOW PRESSURE CIRCULATION AS IT DROPS INTO NORTHERN AZ EARLY THIS MORNING. MODELS AGREE THAT THIS FEATURE WILL PASS EASTWARD OVER NM ALONG AND A LITTLE NORTH OF INTERSTATE 40 TONIGHT...THEN IT WILL EXIT GRADUALLY EASTWARD THROUGH THE TX PANHANDLE ON TUESDAY. STEADY SNOW THAT HAS BEEN FALLING ON THE WEST SLOPE OF THE CO ROCKIES SHOULD DROP SOUTHWARD INTO NW NM TODAY AND EXTEND SOUTHWARD ALONG THE NM CONTINENTAL DIVIDE. A COLD FRONT WILL PROVIDE A FOCUS FOR PRECIP AS IT PUSHES SOUTHEASTWARD THROUGH WESTERN NM TODAY...THEN THROUGH CENTRAL PARTS OF THE STATE THIS EVENING...AND THROUGH THE PLAINS EARLY TUESDAY MORNING. FOR WESTERN AND CENTRAL AREAS WE WILL CONTINUE WITH ONGOING HEADLINES FOR SNOW...BUT WILL UPGRADE THE JEMEZ MOUNTAINS AND UPPER RIO GRANDE VALLEY TO A WINTER STORM WARNING BASED ON THE TRACK OF THE LOW AND THE LATEST MODEL SNOW AMOUNTS. WILL ALSO ISSUE A WINTER WEATHER ADVISORY FOR THE WEST CENTRAL HIGHLANDS...SANTA FE METRO AREA AND LOWER CHAMA RIVER VALLEY FOR TONIGHT. LIKE THE JEMEZ AND UPPER RIO GRANDE VALLEY...THESE AREAS SHOULD SEE A PERIOD OF MODERATE TO HEAVY SNOW THIS EVENING AS THE COLD FRONT CROSSES FROM THE WEST...THEN SOME LINGERING SNOW LATE TONIGHT AS THE UPPER LOW CROSSES. ASIDE FROM THE WESTERLY UPSLOPE FLOW EVENT ALONG AND WEST OF THE CENTRAL MOUNTAIN CHAIN...AN EASTERLY UPSLOPE EVENT IS EXPECTED EAST OF THE SANGRE DE CRISTOS TONIGHT. THEN...WRAP AROUND MOISTURE WILL KEEP SNOW FALLING ACROSS THE EAST CENTRAL AND NORTHEAST PLAINS ON TUESDAY. THE 00Z GFS AND NAM BOTH DEPICT WARNING CRITERIA SNOW AMOUNTS ACROSS THE PLAINS...BUT THE ECMWF HAS LIGHTER AMOUNTS DESPITE THE SAME COVERAGE AREA OF PRECIP. GIVEN THIS UNCERTAINTY...WE OPTED TO EXPAND THE WINTER STORM WATCH FOR NE NM SOUTHEASTWARD ACROSS QUAY...CURRY AND ROOSEVELT COUNTIES. ALSO...MODEL AGREEMENT ON THE TRACK OF THE LOW AND EASTERLY UPSLOPE FLOW OVERNIGHT GAVE US ENOUGH CONFIDENCE TO UPGRADE THE WINTER STORM WATCH TO A WARNING FOR THE EAST SLOPES OF THE SANGRES AND RATON PASS. UNCERTAINTY REMAINS ABOUT HOW MUCH SNOW WILL FALL ACROSS CENTRAL AND SE NM. MODELS AGREE ON SURPRISINGLY LIGHT QPF AROUND ABQ...THE SANDIAS AND THE CENTRAL HIGHLANDS. THEY TYPICALLY DONT RESOLVE THE NARROW SANDIA AND MANZANO MOUNTAINS VERY WELL...AND THESE RANGES TEND TO WRING OUT SNOW AS COLD FRONTS CROSS FROM THE WEST...SO WE ARE ALSO ISSUING A WINTER WEATHER ADVISORY FOR THE SANDIAS AND MANZANOS WITH THIS MORNINGS FORECAST PACKAGE. WILL LET THE DAY SHIFT DECIDE WHAT TO DO WITH THE ALBUQUERQUE METRO AREA AND CENTRAL HIGHLANDS...SINCE MODELS AGREE ON LIGHTER PRECIP IN THESE AREAS...PERHAPS TOO LIGHT FOR ANY HEADLINES. PRECIP WILL TAPER OFF QUICKLY LATE TUESDAY AFTERNOON. AFTER HIGH TEMPERATURES 12 TO 20 DEGREES BELOW NORMAL ON TUESDAY...TEMPERATURES WILL WARM BUT REMAIN BELOW NORMAL UNDER DRY NW FLOW ALOFT WEDNESDAY. AN UPPER TROUGH WILL DIVE SOUTHEASTWARD ALONG THE FRONT RANGE OF THE ROCKIES THURSDAY THROUGH FRIDAY. THE POTENTIAL EXISTS FOR A FEW INCHES OF SNOW ACCUMULATION ALONG AND EAST OF THE NORTHERN AND CENTRAL MOUNTAINS MAINLY THURSDAY NIGHT AND FRIDAY. 44 .FIRE WEATHER... AN ACTIVE WX SCENARIO WILL CONTINUE THRU THIS WEEK WITH BOUTS OF SNOW...COLD...AND WIND...THEN MILDER TEMPS AND DRY BREEZY CONDITIONS OVER THE WEEKEND. THE PACIFIC COLD FRONT AND ASSOCIATED SNOW BAND IS POSITIONED OVER AZ AND FAR WESTERN NM...WHILE THE PLAINS FRONT IS BACKING INTO THE NE CORNER. AN UPPER LEVEL WAVE WILL SLIDE OVER THESE TWO FRONTS AS THEY CONVERGE OVER NM ALLOWING FOR WIDESPREAD SNOW FIRST OVER THE WEST TODAY/TONIGHT THEN OVER THE EAST TONIGHT/ TUESDAY. MUCH NEEDED ADDITIONAL SNOW ACCUMS OVER THE HIGHER TERRAIN WILL CONTINUE ADDING TO OUR BELOW NORMAL SNOWPACK. TEMPS WILL BE COLD WITH THIS WINTER SYSTEM BOTH TODAY AND TUESDAY... WITH SLIGHTLY MILDER CONDITIONS FOR WEDNESDAY. MIN RH VALUES WILL BE QUITE HIGH AS A RESULT OF THE SNOW MONDAY/TUESDAY AS WELL AS WEDNESDAY DESPITE VERY DRY AIR WORKING INTO THE REGION BEHIND THE WAVE. WIDESPREAD VERY GOOD TO EXCELLENT MAX RH RECOVERIES ARE ALSO ON TAP. VENT RATES WILL START OUT VERY GOOD TO EXCELLENT TODAY FOR CENTRAL NM WITH SW FLOW AHEAD OF THE WAVE...DECREASE TUESDAY...THEN BECOME POOR AREAWIDE BY WEDNESDAY AS WINDS ALOFT WEAKEN. ANOTHER WAVE WILL SLIDE SOUTH OVER THE AREA THURSDAY AND REINFORCE THE COLD AIR AND INCREASE LOW LEVEL MOISTURE ONCE AGAIN. MODELS DISAGREE ON PRECIP DEVELOPMENT OVER THE NORTHEAST WITH THIS SYSTEM. A RIDGE IS THEN ANTICIPATED TO MOVE SLOWLY OVER THE REGION LATE FRIDAY INTO THE WEEKEND. STRONG TEMP INVERSIONS WILL BE GREATEST FRIDAY AND SATURDAY MORNING...LEADING TO POOR VENT RATES. BREAK DOWN OF THIS RIDGE SUNDAY/MONDAY MAY LEAD TO CRITICAL FIRE WX CONDITIONS FOR EASTERN NM IN ASSOCIATION WITH A MID LEVEL DRY SLOT. GUYER && .ABQ WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM THIS EVENING THROUGH TUESDAY AFTERNOON FOR THE FOLLOWING ZONES...NMZ528>532-534>536. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM MST TUESDAY FOR THE FOLLOWING ZONES...NMZ507-517-518-521. WINTER WEATHER ADVISORY UNTIL 6 AM MST TUESDAY FOR THE FOLLOWING ZONES...NMZ501-504>506. WINTER STORM WARNING UNTIL 6 AM MST TUESDAY FOR THE FOLLOWING ZONES...NMZ502-503-510>516-527. && $$
AREA FORECAST DISCUSSION
NWS BUFFALO NY
448 AM EST MON FEB 11 2013 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL MOVE INTO SOUTHERN QUEBEC TODAY. THIS WILL BRING A PERIOD OF RAIN EARLY TODAY...WITH SOME FREEZING RAIN ACROSS THE INTERIOR VALLEYS AND A WINTRY MIX EAST OF LAKE ONTARIO. AFTER THIS WINDS WILL INCREASE BEHIND AN ASSOCIATED COLD FRONT...CAUSING RAIN SHOWERS TO CHANGE TO SNOW LATER TODAY AND TONIGHT. && .NEAR TERM /THROUGH TONIGHT/... THERE WILL BE SEVERAL TRANSITIONS TODAY...AS A SERIES OF BOUNDARIES ASSOCIATED WITH LOW PRESSURE ACROSS THE UPPER LAKES INFLUENCES OUR WEATHER. THROUGH THIS MORNING...THE MAIN SOURCE OF LIFT WILL COME FROM AN AREA OF WARM AIR ADVECTION ALOFT. RADAR TRENDS SUGGEST STEADIEST RAINS WILL FOCUS NORTH OF A BUFFALO TO ROCHESTER LINE...WITH LIGHTER QPFS ACROSS THE SOUTHERN TIER. FORTUNATELY...TEMPERATURES SHOULD REMAIN JUST ABOVE FREEZING IN THESE LOCATIONS...WITH DOWNSLOPING OFFSETTING EVAPORATIONAL COOLING. A FREEZING RAIN ADVISORY REMAINS IN EFFECT ACROSS THE INTERIOR...WHERE TEMPERATURES AT 400 AM ARE IN THE LOWER TO MID 30S. HOWEVER...WITH DEW POINTS IN THE 20S EXPECT EVAPORATIONAL COOLING TO DROP TEMPERATURES A FEW DEGREES AS THE RAIN STARTS. RADAR TRENDS ARE MUCH BETTER CAPTURED BY THE HRRR THAN THE NAM/GFS/RGEM WHICH ARE TOO HIGH ON QPF ACROSS THE SOUTHERN TIER. FOLLOWING THIS...EXPECT A FEW HUNDREDTHS OF AN INCH OF QPF ACROSS INTERIOR PORTIONS OF WESTERN NEW YORK...HOWEVER THIS WILL FALL AS FREEZING RAIN IN MANY SPOTS...SO WILL KEEP THE ADVISORY UP. STEADIER PRECIPITATION WILL MOVE EAST OF LAKE ONTARIO THROUGH DAYBREAK...BRINGING THE GREATEST ICING POTENTIAL FOR THIS EVENT. THERE WILL BE MODEST DOWNSLOPE WARMING HERE TOO...BUT WITH DRY AND COOLER AIR IN PLACE EXPECT AROUND A TENTH OF AN INCH OF FREEZING RAIN GLAZE...WITH PERHAPS SOME LIGHT SNOW OR SLEET ACCUMULATION. ALL OF THIS PRECIPITATION SHOULD LIFT FROM SW- NE...ENDING ACROSS WESTERN PORTIONS AROUND DAYBREAK...AND LATE THIS MORNING EAST OF LAKE ONTARIO. THIS SHOULD PROVIDE A BRIEF LULL IN THE ACTION UNTIL THE NEXT BOUNDARY CROSSES. THE NEXT PHASE OF THIS EVENT WILL COME AS THE COLD/OCCLUDED FRONT ASSOCIATED WITH THE UPPER LOW MOVES ACROSS THE REGION. IT WILL ENTER WESTERN NEW YORK AROUND NOON...SWEEPING TO EAST OF LAKE ONTARIO AROUND SUNSET. THIS WILL BRING MAINLY SCATTERED RAIN SHOWERS...BUT ITS MORE SIGNIFICANT IMPACT WILL BE AN INCREASE IN WINDS BEHIND IT. GUSTY SOUTHWESTERLY WINDS WILL PICK UP FIRST ACROSS THE NIAGARA FRONTIER...SPREADING TO THE EAST LATE AFTERNOON AND EVENING. THE LOW IS NOT PARTICULARLY DEEP...NOR IS THE COLD ADVECTION TOO STRONG. WITH ONLY MODEST PRESSURE RISES DONT EXPECT EXTREMELY DEEP MIXING TO TAP THE 50 KNOTS ALOFT...BUT STILL SUFFICIENT TO BRING ADVISORY CRITERIA GUSTS OF 45 TO 50 MPH LATER IN THE AFTERNOON. THE 230-240 DEGREE WIND DIRECTION FAVORS THE STRONGER WINDS FROM THE LAKE ERIE SHORE ACROSS THE NIAGARA FRONTIER TO ROCHESTER. LATER IN THE EVENING WINDS BECOME MORE WESTERLY...WHICH WILL SPREAD STRONGER WINDS INTO THE INTERIOR SOUTHERN TIER AND WESTERN FINGER LAKES. A WIND ADVISORY REMAINS IN EFFECT ACROSS ALL BUT THE EASTERN LAKE ONTARIO REGION. BEHIND THE COLD FRONT...THE UPPER LEVEL TROF ASSOCIATED WITH THE LOW WILL MOVE ACROSS THE REGION. THIS WILL USHER IN COLDER AIR BOTH ALOFT AND AT THE SURFACE. ITS IMPORTANT TO NOTE THAT THIS IS NOT A VERY COLD AIR MASS...WITH 850 MB TEMPERATURES LIKELY TO DROP TO AROUND -10C TONIGHT. THIS IS NOT REALLY COLD ENOUGH FOR PURE LAKE EFFECT...BUT WITH SIGNIFICANT MOISTURE ASSOCIATED WITH THE UPPER TROF...AND SOME UPSLOPE ENHANCEMENT...EXPECT THERE WILL BE SOME SNOW EAST AND NORTHEAST OF THE LAKES TONIGHT. GIVEN THE MINIMAL CONTRIBUTION FROM LAKE INSTABILITY...EXPECT QPFS ARE A BIT OVERDONE BY THE NAM/RGEM WITH THE UPSLOPE...BUT DO FEEL SOME PRECIPITATION IS CERTAINLY REASONABLE. SNOW RATIOS SHOULD NOT BE GREAT GIVEN THE MARGINALLY COLD AIR...WITH 2 OR 3 INCHES SNOW ACCUMULATION LIKELY ON THE TUG HILL TONIGHT...AND A BIT LESS ON THE CHAUTAUQUA RIDGE. IF THERE WERE NOT ALREADY ADVISORIES IN PLACE...THIS PORTION OF THE EVENT COULD REQUIRE A SNOW ADVISORY...BUT WITH A BREAK BETWEEN THE TWO WILL HANDLE THIS AS TWO EVENTS RATHER THAN COMPLICATING THE ISSUE. THIS IS A CHALLENGING EVENT...BECAUSE IF MODEL QPF DOES VERIFY OR IF SNOW RATIONS EXCEED 20 TO 1...THEN THIS COULD ACTUALLY APPROACH WARNING CRITERIA ON THE TUG HILL. AT THIS TIME...NEITHER OF THESE SCENARIOS APPEAR LIKELY. SNOWS WILL BE LESS OFF LAKE ERIE...BUT THE SW FLOW MAY BRING AN INCH OR SO ACROSS THE BUFFALO METRO AREA...WITH LOCALLY HIGHER AMOUNTS ACROSS THE BOSTON HILLS AND CHAUTAUQUA RIDGE. OTHERWISE...TEMPERATURES WILL WARM BRIEFLY TODAY...ESPECIALLY IN THE FINGER LAKES REGION...WITH HIGHS IN THE 40S AHEAD OF THE FRONT. WINDS WILL BE GUSTY FOR A FEW HOURS THROUGH DAYBREAK ALONG I-90 FROM THE NY/PA LINE TO BUFFALO AS DOWNSLOPING RESULTS IN GUSTS UP TO 40 MPH. 925 MB WINDS WILL DIMINISH AFTER 12Z...DIMINISHING WINDS HERE UNTIL THE FRONT MOVES THROUGH. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... ON TUESDAY A SURFACE COLD FRONT WILL BE WELL TO THE EAST WITH COLD AIR ADVECTING ACROSS THE EASTERN GREAT LAKES. THIS WILL BE A MARGINAL SET UP FOR LAKE EFFECT SNOW...WITH THE MAIN FORCING MECHANISM BEING MORE THE UPSLOPE FLOW OVER HIGHER TERRAIN EAST OF BOTH GREAT LAKES. TEMPERATURES AT 850 HPA WILL DROP TO AROUND -10C THROUGH THE DAY TUESDAY WHICH CREATES VERY LITTLE INSTABILITY OFF LAKE ERIE...AND ONLY MINOR LAKE INSTABILITY OFF LAKE ONTARIO. WHILE THERE WILL BE PLENTY OF MOISTURE IN THE LOWER LEVELS...DRIER AIR BEHIND AN UPPER LEVEL SHORTWAVE WILL LOWER THIS MOISTURE TO JUST BELOW THE SNOW CRYSTAL GROWTH ZONE...AND WITH WEAK UPWARD OMEGA FORCING THERE WILL NOT BE GOOD SNOW CRYSTAL GROWTH. WILL CONTINUE WITH LIKELY POPS ACROSS THE HIGHER TERRAIN SOUTH OF BUFFALO...AND CATEGORICAL POPS EAST OF LAKE ONTARIO WHERE LAKE ENHANCEMENT TO THE UPSLOPE SNOW SHOWERS SHOULD BRING SEVERAL INCHES DURING THE DAY TUESDAY. ANOTHER WEAK SHORTWAVE WILL CROSS WNY TUESDAY AND THIS WILL KEEP LOW CHANCE POPS FOR A SNOW SHOWER EVEN ACROSS THE LOWER ELEVATIONS. THIS SHORTWAVE WILL ALSO CAUSE LAKE ENHANCEMENT TO BE TRANSITORY THROUGH THE DAY. A WINTER WEATHER ADVISORY MAY BE NEEDED FOR THIS SNOW EVENT FOR THE TUG HILL REGION CONTINUING INTO TUESDAY...AND TUESDAY NIGHT. HOWEVER WITH A CURRENT WINTER WEATHER ADVISORY ALREADY IN PLACE WILL JUST MENTION THE PROSPECTS FOR ADVISORY LEVEL SNOWS IN THE HWO. HIGHS ON TUESDAY WILL NOT CLIMB TOO MUCH FROM THEIR MORNING LOWS...WITH TEMPERATURES THROUGH THE DAY LARGELY IN THE LOW TO MID 30S. WINDS WILL CONTINUE TO BE GUSTY THROUGH THE MORNING HOURS BUT AS THE SURFACE LOW CARRIES FARTHER EASTWARD THROUGH ATLANTIC CANADA AND WINDS ALOFT WEAKEN THE GUSTY SURFACE WINDS SHOULD DIMINISH THROUGH THE DAY. TUESDAY NIGHT SOME DRIER AIR BEGINS TO FILTER ACROSS THE GREAT LAKES...YET THERE SHOULD STILL BE ENOUGH MOISTURE TO MAINTAIN THESE SNOW SHOWERS...ESPECIALLY EAST OF LAKE ONTARIO. WITH THE FLOW VEERING A LITTLE THE SNOW SHOWERS ACROSS THE EASTERN LAKE ONTARIO REGION WILL BE MORE FOCUSED UPON OSWEGO AND SOUTHERN LEWIS COUNTIES. WEDNESDAY FURTHER DRYING ALOFT AND WARM AIR ADVECTION WILL BRING AN END TO THE WEAK LAKE ENHANCED SNOW SHOWERS EAST OF LAKE ONTARIO. EXPECT JUST A CHANCE FOR MORNING LAKE EFFECT SNOW...CARRYING NORTHWARD AND WEAKENING TO FLURRIES JUST SOUTH OF WATERTOWN. HIGH PRESSURE WILL CROSS OUR REGION...CENTERED TO OUR SOUTH...AND WITH THE AXIS OF A WEAK UPPER LEVEL RIDGE CROSSING THE EASTERN GREAT LAKES WE SHOULD SEE ADDITIONAL SUNSHINE THROUGH THE DAY. CLOUDS WILL BEGIN TO THICKEN FROM THE SOUTH WEDNESDAY AFTERNOON AND EVENING WELL AHEAD OF A STORM SYSTEM CROSSING THE SOUTHEAST. A PRIMARY SURFACE LOW WILL TRACK TO ABOUT WESTERN PENNSYLVANIA BEFORE AN UPPER LEVEL SHORTWAVE TROUGH TRANSFERS ENERGY TO A DEVELOPING COASTAL LOW THAT WILL QUICKLY DEEPEN. IT LOOKS LIKE THIS SYSTEM WILL MISS OUR AREA...WITH JUST A SLIGHT CHANCE THAT SOME LIGHT SNOW WILL BRUSH BY THE UPPER GENESEE RIVER VALLEY EARLY WEDNESDAY NIGHT. WITH THE WARM AIR ADVECTION ALOFT AND WINDS FROM THE SOUTHEAST HIGHS WEDNESDAY WILL CLIMB SEVERAL DEGREES WARMER THAN TUESDAY. HIGHS ON WEDNESDAY WILL CLIMB INTO THE MID AND UPPER 30S WITH A SPOT 40 POSSIBLE. && .LONG TERM /THURSDAY THROUGH SUNDAY/... DURING THIS PERIOD...GFS/ECMWF FEATURE THE DEVELOPMENT OF A HIGH AMPLITUDE RIDGE OVER THE WESTERN UNITED STATES AND A LARGE BROAD TROUGH OVER THE EASTERN 2/3 OF THE U.S FROM THE COLORADO ROCKIES TO THE EASTERN SEA BOARD. INITIALLY...TEMPERATURES WILL START OUT SLIGHTLY ABOVE CLIMATOLOGY AND THEN ARE FORECAST TO GRADUALLY TREND COLDER THROUGH THE WEEKEND SATURDAY TO SUNDAY. A CLIPPER-TYPE LOW PRESSURE SYSTEM WILL SET THE STAGE...IT IS FORECAST TO TRACK JUST TO THE WEST OF THE REGION ACROSS THE UPPER GREAT LAKES. SOUTHERLY WINDS AHEAD OF THIS SYSTEM WILL PICK UP ACROSS THE REGION..THEN A COLD FRONT WILL CROSS WESTERN AND NORTH CENTRAL NEW YORK THURSDAY NIGHT INTO FRIDAY...BRINGING WITH IT A CHANCE OF RAIN AND SNOW SHOWERS. COLDER AIR FOLLOWING THIS SYSTEM WILL BRING A CHANCE FOR MORE SNOW SHOWERS AND POSSIBLE LAKE EFFECT SNOW FRIDAY NIGHT AND SATURDAY. HOWEVER...THERE ARE DIFFERENCES BETWEEN THE GFS/ECMWF WITH TIMING AND THE GENERAL STRENGTH OF THE CLIPPER-TYPE SYSTEM FORECAST TO MOVE ACROSS THE REGION. AT THIS POINT...IT SEEMS LIKELY THAT WESTERN/NORTH CENTRAL NY WILL SEE A GRADUAL RETURN TO COLDER TEMPERATURES OVER THE PERIOD. && .AVIATION /10Z MONDAY THROUGH FRIDAY/... STEADIEST PRECIPITATION WILL LIFT ACROSS THE REGION FROM W-E THROUGH 15Z. EXPECT A COUPLE HOURS OF LIGHT RAIN AT MOST TAF SITES...WITH SOME -FZRA AT JHW/ART WHERE TEMPERATURES WILL BE A BIT COOLER. DOWNSLOPING SHOULD KEEP CIGS MVFR OR HIGHER AT MOST TAF LOCATIONS...BUT A PERIOD OF IFR OR LOWER CIGS IS LIKELY AT JHW WHICH DOES NOT DRY AS WELL IN THIS TYPE OF FLOW. PRECIPITATION WILL END LATE THIS MORNING...PROVIDING A BRIEF BREAK BEFORE THE NEXT ROUND OF SHOWERS MOVES IN THIS AFTERNOON. THERE STILL MAY BE LINGERING MOISTURE AND MVFR CIGS AHEAD OF THE COLD FRONT. SHOWERS WILL EVENTUALLY TRANSITION TO SNOW SHOWERS AS COLDER AIR WORKS IN. BESIDES THE RISK OF MIXED WINTRY PRECIPITATION...THERE WILL BE SOME LOW LEVEL WIND SHEAR TO CONTEND WITH THIS MORNING. WINDS AT 1500-2000 FT WILL AVERAGE 40-50 KTS WHILE SFC WINDS WILL BE IN THE VCNTY OF 10 KNOTS. BY THIS AFTERNOON...THE STRONGER WINDS ALOFT SHOULD BE AT LEAST PARTIALLY MIXING TO THE SFC. WIND GUSTS OVER 30 KTS WILL BE POSSIBLE AT KIAG AND KBUF LATER IN THE AFTERNOON. TONIGHT...MVFR CONDITIONS WILL BE LIKELY WITH VSBYS BEING LOWERED IN SNOW SHOWERS. THE MOST WIDESPREAD SNOWS WILL BE GENERATED EAST OF BOTH LAKES WHERE IFR CONDITIONS WILL BE POSSIBLE. OUTLOOK... TUESDAY...MVFR/IFR IN LIGHT SNOW SHOWERS. WEDNESDAY AND THURSDAY...MAINLY VFR. FRIDAY...MVFR/IFR WITH A CHANCE OF SNOW. && .MARINE... SOUTHERLY WINDS WILL BE GUSTY THIS MORNING...ESPECIALLY ON LAKE ERIE...AS STRONG WINDS ALOFT OCCASIONALLY MIX DOWN. AFTER THIS...EXPECT A BIT OF LULL...BEFORE A COLD FRONT CROSSES THE WATERS AROUND MIDDAY. THIS WILL SHIFT WINDS TO THE SOUTHWEST AND CAUSE AN INCREASE TO 35 KNOT GALES BEHIND THE FRONT. EXPECT GALES TO CONTINUE THROUGH TONIGHT...GRADUALLY SUBSIDING FROM WEST TO EAST ON TUESDAY. HIGH PRESSURE WILL BUILD ACROSS THE REGION WEDNESDAY...WITH NO HEADLINES ANTICIPATED. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...FREEZING RAIN ADVISORY UNTIL 8 AM EST THIS MORNING FOR NYZ004- 005-012>014-019>021-085. WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 5 AM EST TUESDAY FOR NYZ001>003-010>012-019-085. WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NYZ007-008. FREEZING RAIN ADVISORY UNTIL 10 AM EST THIS MORNING FOR NYZ006. WIND ADVISORY FROM 6 PM THIS EVENING TO 5 AM EST TUESDAY FOR NYZ004-013-014-020-021. MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR LEZ040- 041. GALE WARNING FROM 1 PM THIS AFTERNOON TO 4 AM EST TUESDAY FOR LEZ020-040-041. GALE WARNING FROM 1 PM THIS AFTERNOON TO 10 AM EST TUESDAY FOR LOZ042-043-062-063. SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR LOZ045. GALE WARNING FROM 4 PM THIS AFTERNOON TO 1 PM EST TUESDAY FOR LOZ044-045-064-065. && $$ SYNOPSIS...APFFEL NEAR TERM...APFFEL SHORT TERM...THOMAS LONG TERM...AR AVIATION...APFFEL MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
425 AM EST MON FEB 11 2013 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL MOVE INTO SOUTHERN QUEBEC TODAY. THIS WILL BRING A PERIOD OF RAIN EARLY TODAY...WITH SOME FREEZING RAIN ACROSS THE INTERIOR VALLEYS AND A WINTRY MIX EAST OF LAKE ONTARIO. AFTER THIS WINDS WILL INCREASE BEHIND AN ASSOCIATED COLD FRONT...CAUSING RAIN SHOWERS TO CHANGE TO SNOW LATER TODAY AND TONIGHT. && .NEAR TERM /THROUGH TONIGHT/... THERE WILL BE SEVERAL TRANSITIONS TODAY...AS A SERIES OF BOUNDARIES ASSOCIATED WITH LOW PRESSURE ACROSS THE UPPER LAKES WILL INFLUENCE OUR WEATHER. THROUGH THIS MORNING...THE MAIN SOURCE OF LIFT WILL COME FROM AN AREA OF WARM AIR ADVECTION ALOFT. RADAR TRENDS SUGGEST STEADIEST RAINS WILL FOCUS NORTH OF A BUFFALO TO ROCHESTER LINE...WITH LIGHTER QPFS ACROSS THE SOUTHERN TIER. FORTUNATELY...TEMPERATURES SHOULD REMAIN JUST ABOVE FREEZING IN THESE LOCATIONS...WITH DOWNSLOPING OFFSETTING EVAPORATIONAL COOLING. A FREEZING RAIN ADVISORY REMAINS IN EFFECT ACROSS THE INTERIOR...WHERE TEMPERATURES AT 400 AM ARE IN THE LOWER TO MID 30S. HOWEVER...WITH RAIN MOVING IN AND DEW POINTS IN THE 20S...EXPECT TEMPERATURES TO DROP A FEW DEGREES AS RAIN STARTS. RADAR TRENDS ARE WELL CAPTURED BY THE HRRR (THE NAM/GFS/RGEM ARE TOO HIGH FOR QPF ACROSS THE INTERIOR). FOLLOWING THIS...EXPECT SOME LIGHT (A FEW HUNDREDTHS OF AN INCH) QPF HOWEVER THIS WILL FALL AS FREEZING RAIN IN MANY SPOTS...SO WILL KEEP THE ADVISORY UP. STEADIER PRECIPITATION WILL MOVE EAST OF LAKE ONTARIO THROUGH DAYBREAK...BRINGING THE GREATEST ICING POTENTIAL FOR THIS EVENT. THERE WILL BE MODEST DOWNSLOPE WARMING HERE TOO...BUT WITH DRY AND COOLER AIR IN PLACE EXPECT AROUND A TENTH OF AN INCH OF FREEZING RAIN GLAZE...WITH PERHAPS SOME LIGHT SNOW OR SLEET ACCUMULATION. ALL OF THIS PRECIPITATION SHOULD LIFT FROM SW-NE...ENDING ACROSS WESTERN PORTIONS AROUND DAYBREAK...AND LATE THIS MORNING EAST OF LAKE ONTARIO. THIS SHOULD PROVIDE A BRIEF LULL IN THE ACTION UNTIL THE NEXT BOUNDARY CROSSES. THE NEXT PHASE OF THIS EVENT WILL COME AS THE COLD FRONT ASSOCIATED WITH THE LOW MOVES ACROSS THE REGION. IT WILL ENTER WESTERN NEW YORK AROUND NOON...SWEEPING TO EAST OF LAKE ONTARIO AROUND SUNSET. THIS WILL BRING MAINLY SCATTERED RAIN SHOWERS...BUT ITS MORE SIGNIFICANT IMPACT WILL BE AN INCREASE IN WINDS BEHIND IT. GUSTY SOUTHWESTERLY WINDS WILL PICK UP FIRST ACROSS THE NIAGARA FRONTIER...SPREADING TO THE EAST LATE AFTERNOON AND EVENING. THE LOW IS NOT PARTICULARLY DEEP...NOR IS THE COLD ADVECTION TOO STRONG. WITH ONLY MODEST PRESSURE RISES DONT EXPECT EXTREMELY DEEP MIXING TO TAP THE 50 KNOTS ALOFT...BUT STILL SUFFICIENT TO BRING ADVISORY CRITERIA GUSTS OF 45 TO 50 MPH LATER IN THE AFTERNOON. THE 230-240 DEGREE WIND DIRECTION FAVORS THE STRONGER WINDS FROM THE LAKE ERIE SHORE ACROSS THE NIAGARA FRONTIER TO ROCHESTER. LATER IN THE EVENING WINDS BECOME MORE WESTERLY...WHICH WILL SPREAD STRONGER WINDS INTO THE INTERIOR SOUTHERN TIER AND WESTERN FINGER LAKES. A WIND ADVISORY REMAINS IN EFFECT ACROSS ALL BUT THE EASTERN LAKE ONTARIO REGION. BEHIND THE COLD FRONT...THE UPPER LEVEL TROF ASSOCIATED WITH THE LOW WILL MOVE ACROSS THE REGION. THIS WILL USHER IN COLDER AIR BOTH ALOFT AND AT THE SURFACE. ITS IMPORTANT TO NOTE THAT THIS IS NOT A VERY COLD AIR MASS...WITH 850 MB TEMPERATURES LIKELY TO DROP TO AROUND -10C TONIGHT. THIS IS NOT REALLY COLD ENOUGH FOR PURE LAKE EFFECT...BUT WITH SIGNIFICANT MOISTURE ASSOCIATED WITH THE UPPER TROF...AND SOME UPSLOPE ENHANCEMENT...EXPECT THERE WILL BE SOME SNOW EAST AND NORTHEAST OF THE LAKES TONIGHT. GIVEN THE MINIMAL CONTRIBUTION FROM LAKE INSTABILITY...EXPECT QPFS ARE A BIT OVERDONE BY THE NAM/RGEM WITH THE UPSLOPE...BUT DO FEEL SOME PRECIPITATION IS CERTAINLY REASONABLE. SNOW RATIOS SHOULD NOT BE GREAT GIVEN THE MARGINALLY COLD AIR...WITH 2 OR 3 INCHES SNOW ACCUMULATION LIKELY ON THE TUG HILL TONIGHT...AND A BIT LESS ON THE CHAUTAUQUA RIDGE. IF THERE WERE NOT ALREADY ADVISORIES IN PLACE...THIS PORTION OF THE EVENT COULD REQUIRE A SNOW ADVISORY...BUT WITH A BREAK BETWEEN THE TWO WILL HANDLE THIS AS TWO EVENTS RATHER THAN COMPLICATING THE ISSUE. THIS IS A CHALLENGING EVENT...BECAUSE IF MODEL QPF DOES VERIFY OR IF SNOW RATIONS EXCEED 20 TO 1...THEN THIS COULD ACTUALLY APPROACH WARNING CRITERIA ON THE TUG HILL. AT THIS TIME...NEITHER OF THESE SCENARIOS APPEAR LIKELY. SNOWS WILL BE LESS OFF LAKE ERIE...BUT THE SW FLOW MAY BRING AN INCH OR SO ACROSS THE BUFFALO METRO AREA...WITH LOCALLY HIGHER AMOUNTS ACROSS THE BOSTON HILLS AND CHAUTAUQUA RIDGE. OTHERWISE...TEMPERATURES WILL WARM BRIEFLY TODAY...ESPECIALLY IN THE FINGER LAKES REGION...WITH HIGHS IN THE 40S AHEAD OF THE FRONT. WINDS WILL BE GUSTY FOR A FEW HOURS THROUGH DAYBREAK ALONG I-90 FROM THE NY/PA LINE TO BUFFALO AS DOWNSLOPING RESULTS IN GUSTS UP TO 40 MPH. 925 MB WINDS WILL DIMINISH AFTER 12Z...DIMINISHING WINDS HERE UNTIL THE FRONT MOVES THROUGH. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... ON TUESDAY A SURFACE COLD FRONT WILL BE WELL TO THE EAST WITH COLD AIR ADVECTING ACROSS THE EASTERN GREAT LAKES. THIS WILL BE A MARGINAL SET UP FOR LAKE EFFECT SNOW...WITH THE MAIN FORCING MECHANISM BEING MORE THE UPSLOPE FLOW OVER HIGHER TERRAIN EAST OF BOTH GREAT LAKES. TEMPERATURES AT 850 HPA WILL DROP TO AROUND -10C THROUGH THE DAY TUESDAY WHICH CREATES VERY LITTLE INSTABILITY OFF LAKE ERIE...AND ONLY MINOR LAKE INSTABILITY OFF LAKE ONTARIO. WHILE THERE WILL BE PLENTY OF MOISTURE IN THE LOWER LEVELS...DRIER AIR BEHIND AN UPPER LEVEL SHORTWAVE WILL LOWER THIS MOISTURE TO JUST BELOW THE SNOW CRYSTAL GROWTH ZONE...AND WITH WEAK UPWARD OMEGA FORCING THERE WILL NOT BE GOOD SNOW CRYSTAL GROWTH. WILL CONTINUE WITH LIKELY POPS ACROSS THE HIGHER TERRAIN SOUTH OF BUFFALO...AND CATEGORICAL POPS EAST OF LAKE ONTARIO WHERE LAKE ENHANCEMENT TO THE UPSLOPE SNOW SHOWERS SHOULD BRING SEVERAL INCHES DURING THE DAY TUESDAY. ANOTHER WEAK SHORTWAVE WILL CROSS WNY TUESDAY AND THIS WILL KEEP LOW CHANCE POPS FOR A SNOW SHOWER EVEN ACROSS THE LOWER ELEVATIONS. THIS SHORTWAVE WILL ALSO CAUSE LAKE ENHANCEMENT TO BE TRANSITORY THROUGH THE DAY. A WINTER WEATHER ADVISORY MAY BE NEEDED FOR THIS SNOW EVENT FOR THE TUG HILL REGION CONTINUING INTO TUESDAY...AND TUESDAY NIGHT. HOWEVER WITH A CURRENT WINTER WEATHER ADVISORY ALREADY IN PLACE WILL JUST MENTION THE PROSPECTS FOR ADVISORY LEVEL SNOWS IN THE HWO. HIGHS ON TUESDAY WILL NOT CLIMB TOO MUCH FROM THEIR MORNING LOWS...WITH TEMPERATURES THROUGH THE DAY LARGELY IN THE LOW TO MID 30S. WINDS WILL CONTINUE TO BE GUSTY THROUGH THE MORNING HOURS BUT AS THE SURFACE LOW CARRIES FARTHER EASTWARD THROUGH ATLANTIC CANADA AND WINDS ALOFT WEAKEN THE GUSTY SURFACE WINDS SHOULD DIMINISH THROUGH THE DAY. TUESDAY NIGHT SOME DRIER AIR BEGINS TO FILTER ACROSS THE GREAT LAKES...YET THERE SHOULD STILL BE ENOUGH MOISTURE TO MAINTAIN THESE SNOW SHOWERS...ESPECIALLY EAST OF LAKE ONTARIO. WITH THE FLOW VEERING A LITTLE THE SNOW SHOWERS ACROSS THE EASTERN LAKE ONTARIO REGION WILL BE MORE FOCUSED UPON OSWEGO AND SOUTHERN LEWIS COUNTIES. WEDNESDAY FURTHER DRYING ALOFT AND WARM AIR ADVECTION WILL BRING AN END TO THE WEAK LAKE ENHANCED SNOW SHOWERS EAST OF LAKE ONTARIO. EXPECT JUST A CHANCE FOR MORNING LAKE EFFECT SNOW...CARRYING NORTHWARD AND WEAKENING TO FLURRIES JUST SOUTH OF WATERTOWN. HIGH PRESSURE WILL CROSS OUR REGION...CENTERED TO OUR SOUTH...AND WITH THE AXIS OF A WEAK UPPER LEVEL RIDGE CROSSING THE EASTERN GREAT LAKES WE SHOULD SEE ADDITIONAL SUNSHINE THROUGH THE DAY. CLOUDS WILL BEGIN TO THICKEN FROM THE SOUTH WEDNESDAY AFTERNOON AND EVENING WELL AHEAD OF A STORM SYSTEM CROSSING THE SOUTHEAST. A PRIMARY SURFACE LOW WILL TRACK TO ABOUT WESTERN PENNSYLVANIA BEFORE AN UPPER LEVEL SHORTWAVE TROUGH TRANSFERS ENERGY TO A DEVELOPING COASTAL LOW THAT WILL QUICKLY DEEPEN. IT LOOKS LIKE THIS SYSTEM WILL MISS OUR AREA...WITH JUST A SLIGHT CHANCE THAT SOME LIGHT SNOW WILL BRUSH BY THE UPPER GENESEE RIVER VALLEY EARLY WEDNESDAY NIGHT. WITH THE WARM AIR ADVECTION ALOFT AND WINDS FROM THE SOUTHEAST HIGHS WEDNESDAY WILL CLIMB SEVERAL DEGREES WARMER THAN TUESDAY. HIGHS ON WEDNESDAY WILL CLIMB INTO THE MID AND UPPER 30S WITH A SPOT 40 POSSIBLE. && .LONG TERM /THURSDAY THROUGH SUNDAY/... DURING THIS PERIOD...GFS/ECMWF FEATURE THE DEVELOPMENT OF A HIGH AMPLITUDE RIDGE OVER THE WESTERN UNITED STATES AND A LARGE BROAD TROUGH OVER THE EASTERN 2/3 OF THE U.S FROM THE COLORADO ROCKIES TO THE EASTERN SEA BOARD. INITIALLY...TEMPERATURES WILL START OUT SLIGHTLY ABOVE CLIMATOLOGY AND THEN ARE FORECAST TO GRADUALLY TREND COLDER THROUGH THE WEEKEND SATURDAY TO SUNDAY. A CLIPPER-TYPE LOW PRESSURE SYSTEM WILL SET THE STAGE...IT IS FORECAST TO TRACK JUST TO THE WEST OF THE REGION ACROSS THE UPPER GREAT LAKES. SOUTHERLY WINDS AHEAD OF THIS SYSTEM WILL PICK UP ACROSS THE REGION..THEN A COLD FRONT WILL CROSS WESTERN AND NORTH CENTRAL NEW YORK THURSDAY NIGHT INTO FRIDAY...BRINGING WITH IT A CHANCE OF RAIN AND SNOW SHOWERS. COLDER AIR FOLLOWING THIS SYSTEM WILL BRING A CHANCE FOR MORE SNOW SHOWERS AND POSSIBLE LAKE EFFECT SNOW FRIDAY NIGHT AND SATURDAY. HOWEVER...THERE ARE DIFFERENCES BETWEEN THE GFS/ECMWF WITH TIMING AND THE GENERAL STRENGTH OF THE CLIPPER-TYPE SYSTEM FORECAST TO MOVE ACROSS THE REGION. AT THIS POINT...IT SEEMS LIKELY THAT WESTERN/NORTH CENTRAL NY WILL SEE A GRADUAL RETURN TO COLDER TEMPERATURES OVER THE PERIOD. && .AVIATION /10Z MONDAY THROUGH FRIDAY/... WHILE VFR CONDITIONS WILL BE IN PLACE FOR THE BULK OF THE REGION FOR THE REST OF THE OVERNIGHT...AN AREA OF RAIN OVER LAKE ERIE AND NORTHWEST PENNSYLVANIA WILL LIFT ACROSS OUR REGION DURING THE OVERNIGHT HOURS. THIS PRECIPITATION SHOULD BE IN THE FORM OF RAIN AT THE MAJOR TAF SITES ACROSS WESTERN NEW YORK (KBUF/KROC)...BUT THERE IS A SLIGHT CHANCE THAT IT COULD FALL AS A BRIEF PERIOD OF -FZRA AT KJHW. OTHERWISE...CIGS SHOULD DETERIORATE TO AT LEAST MVFR ACROSS PARTS OF THE SRN TIER. AS THE PCPN PUSHES FURTHER EAST BY DAYBREAK...A WINTRY MIX OF FREEZING RAIN...SLEET AND EVEN SNOW WILL BE POSSIBLE AT KART. ON MONDAY...THE PCPN WILL END FROM WEST TO EAST IN THE FORM OF JUST RAIN...WITH AN ENDING TIME OF 12-14Z OVER THE WESTERN COUNTIES AND 16Z EAST OF LK ONTARIO. CIGS WILL LIKELY DROP TO MVFR FOR A FEW HOURS IN THE WAKE OF THE STEADIER PCPN...WITH SOME IFR CIGS POSSIBLE AT KJHW AND KELZ. THESE CIGS SHOULD GENERALLY IMPROVE DURING THEM MIDDAY AND AFTERNOON. BESIDES THE RISK OF MIXED WINTRY PRECIPITATION...THERE WILL BE SOME LOW LEVEL WIND SHEAR TO CONTEND WITH TONIGHT AND FOR AT LEAST THE MORNING HOURS OF MONDAY. WINDS AT 1500-2000 FT WILL AVERAGE 40-50 KTS WHILE SFC WINDS WILL BE IN THE VCNTY OF 10 KNOTS. BY MONDAY AFTERNOON...THE STRONGER WINDS ALOFT SHOULD BE AT LEAST PARTIALLY MIXING TO THE SFC. WIND GUSTS OVER 30KTS WILL BE POSSIBLE AT KIAG AND KBUF LATER IN THE AFTERNOON. ON MONDAY NIGHT...MVFR CONDITIONS WILL BE LIKELY WITH VSBYS BEING LOWERED IN SNOW SHOWERS. THE MOST WIDESPREAD SNOWS WILL BE GENERATED EAST OF BOTH LAKES WHERE IFR CONDITIONS WILL BE POSSIBLE. OUTLOOK... TUESDAY...MVFR/IFR IN LIGHT SNOW SHOWERS. WEDNESDAY AND THURSDAY...MAINLY VFR. FRIDAY...MVFR/IFR WITH A CHANCE OF SNOW. && .MARINE... SOUTHERLY WINDS WILL BE GUSTY THIS MORNING...ESPECIALLY ON LAKE ERIE...AS STRONG WINDS ALOFT OCCASIONALLY MIX DOWN. AFTER THIS...EXPECT A BIT OF LULL...BEFORE A COLD FRONT CROSSES THE WATERS AROUND MIDDAY. THIS WILL SHIFT WINDS TO THE SOUTHWEST AND CAUSE AN INCREASE TO 35 KNOT GALES BEHIND THE FRONT. EXPECT GALES TO CONTINUE THROUGH TONIGHT...GRADUALLY SUBSIDING FROM WEST TO EAST ON TUESDAY. HIGH PRESSURE WILL BUILD ACROSS THE REGION WEDNESDAY...WITH NO HEADLINES ANTICIPATED. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...FREEZING RAIN ADVISORY UNTIL 8 AM EST THIS MORNING FOR NYZ004- 005-012>014-019>021-085. WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 5 AM EST TUESDAY FOR NYZ001>003-010>012-019-085. WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NYZ007-008. FREEZING RAIN ADVISORY UNTIL 10 AM EST THIS MORNING FOR NYZ006. WIND ADVISORY FROM 6 PM THIS EVENING TO 5 AM EST TUESDAY FOR NYZ004-013-014-020-021. MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR LEZ040- 041. GALE WARNING FROM 1 PM THIS AFTERNOON TO 4 AM EST TUESDAY FOR LEZ020-040-041. GALE WARNING FROM 1 PM THIS AFTERNOON TO 10 AM EST TUESDAY FOR LOZ042-043-062-063. SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR LOZ045. GALE WARNING FROM 4 PM THIS AFTERNOON TO 1 PM EST TUESDAY FOR LOZ044-045-064-065. && $$ SYNOPSIS...APFFEL NEAR TERM...APFFEL SHORT TERM...THOMAS LONG TERM...AR AVIATION...RSH MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
310 PM EST MON FEB 11 2013 .SYNOPSIS... A COLD FRONT WILL CROSS THE REGION THIS EVENING BEFORE SETTLING JUST TO OUR SOUTH LATE TONIGHT. WEAK HIGH PRESSURE WILL MOVE IN LATE TONIGHT THROUGH TUESDAY. A LOW PRESSURE SYSTEM WILL TRACK ALONG THE FRONT TUESDAY NIGHT AND WEDNESDAY... BRINGING UNSETTLED WEATHER. && .NEAR TERM /THROUGH TUESDAY NIGHT/... AS OF 245 PM MONDAY... THROUGH TONIGHT: AS EXPECTED... THE WEDGE AIR MASS OVER THE TRIAD REGION HAS BEEN VERY TOUGH TO DISLODGE... AS EARLY AFTERNOON TEMPS REMAIN IN THE LOWER 50S WITH FOG AND VERY LOW STRATUS HOLDING ON... WHILE READINGS ARE MOSTLY IN THE 60S ELSEWHERE. SW WINDS JUST OFF THE SURFACE (AT 1-2 KFT AGL) ARE NOT QUITE AS STRONG AS THEY WERE THIS MORNING WITH THE DEPARTURE OF THE LOW LEVEL JET TO THE EAST BUT THEY CONTINUE TO PULL IN ENOUGH WARM AIR ALOFT SUCH THAT THE SURFACE-BASED STABLE LAYER IS REINFORCED VIA DIFFERENTIAL TEMP ADVECTION IN THE VERTICAL... DESPITE THE LACK OF A FEED OF COOL AIR AT THE SURFACE. AS SUCH... WE MAY SEE A MUTED FORM OF THIS WEDGE AIR MASS HANG IN OVER THE TRIAD THROUGH THIS EVENING... UNTIL THE COLD FRONT FINALLY SWEEPS THROUGH. LATEST CONVECTION-ALLOWING MODEL RUNS INCLUDING THE HRRR AND HIGH-RES WRF-NMM AND WRF-ARW SHOW WEAK LOW PRESSURE OVER NRN GA TRACKING ALONG THE FRONT AND IS ASSOCIATED WITH THE UPSTREAM PRECIP BAND NOW ACROSS NRN GA AND UPSTATE SC STREAMING TO THE ENE ACROSS THE FAR SRN/SE CWA... HOWEVER PREFRONTAL CONVECTION TO THE SSE OVER SRN GA MAY INTERRUPT THE POLEWARD MOISTURE TRANSPORT SUCH THAT WE`LL ONLY SEE LIGHT AMOUNTS AT MOST. WILL HOLD ONTO THE LOW CHANCE POPS OVER THE FAR SRN AND SE CWA THROUGH THIS EVENING... WITH DRY WEATHER OVERNIGHT. A SUBTLE MID LEVEL WAVE CONNECTED TO THE VORTEX CROSSING FAR SE ONTARIO AND SRN QUEBEC WILL CROSS THE MIDATLANTIC REGION LATER TONIGHT... FLATTENING THE MID LEVEL FLOW AND PROPELLING THE SURFACE FRONT TO OUR SOUTHEAST. THIS FLOW WILL REMAIN QUITE SWIFT TONIGHT... 80-90 KTS AT 500 MB... WITH PLENTY OF MOISTURE AT 310K-320K... SO EXPECT ABUNDANT MID LEVEL CLOUDS TO STREAM ACROSS THE AREA THROUGH THE NIGHT. LOWS 39-47. FOR TUESDAY/TUESDAY NIGHT: WILL SEE A BRIEF RESPITE IN THE ACTIVE PATTERN ON TUESDAY BEFORE THE RAIN RAMPS BACK UP TUESDAY EVENING. THE FRONT WILL HOLD TO OUR SOUTH WITH WEAK HIGH PRESSURE BUILDING OVER THE REGION. MID LEVEL FLOW REMAINS FAST (NEAR 80 KTS) OVER THE REGION BUT WILL BECOME GENTLY ANTICYCLONIC FOR A TIME... AS THE DEEP TROUGH LOCATED OVER THE FOUR CORNERS REGION STARTS TO KICK EASTWARD INTO THE SRN PLAINS. WE`LL LIKELY SEE PARTLY SUNNY SKIES GIVE WAY TO GREATER SUNSHINE TOWARD AFTERNOON... PARTICULARLY ACROSS THE NORTHERN CWA. LOW LEVEL THICKNESSES AS WELL AS THE LOW LEVEL THERMAL STRUCTURE SUPPORT HIGHS IN THE UPPER 50S TO LOWER 60S. THE MID LEVEL TROUGH SHIFTS THROUGH THE MID MISS VALLEY AS A POSITIVELY-TILTED WEAKENING WAVE... AND MODELS ALL AGREE ON A RAPID INCREASE IN DEEP MOIST ISENTROPIC UPGLIDE FROM 285K-305K OUT AHEAD OVER THE CAROLINAS. SIMILAR TO LAST NIGHT`S RAINFALL PATTERN... WITH THE FRONT LIKELY TO STILL HOLD SOUTH OF THE NC BORDER THROUGH TUESDAY NIGHT AND WITH INCREASING LAPSE RATES AND INSTABILITY OVER MS/AL/GA... WE SHOULD SEE THE GREATEST RISK OF HEAVY PRECIP CONFINED TO ALONG AND SOUTH OF THE BORDER. WITH A GOOD CHANCE OF A CONVECTIVE BAND WELL TO OUR SOUTH AND SW TUESDAY NIGHT... MOISTURE TRANSPORT MAY BE SUFFICIENTLY REDUCED TO GREATLY LIMIT AMOUNTS AND COVERAGE OVER NRN NC. NEVERTHELESS... GIVEN THE RESURGENCE OF 1+ INCH PRECIP WATER INTO THE SRN AND ERN CWA OVERNIGHT... CONFIDENCE IS HIGH ENOUGH FOR CATEGORICAL POPS IN THE SRN/SE CWA... TRENDING TO GOOD CHANCE NEAR THE VA BORDER. AMOUNTS ALONG/NORTH OF HIGHWAY 64 MAY BE LESS THAN A TENTH... WHILE AREAS NEAR THE SC BORDER COULD SEE A HALF INCH OR MORE. LOWS 40-46. -GIH && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 310 PM MONDAY... SHORTWAVE EJECTING OUT OF THE FOUR CORNERS REGION TUESDAY WILL RACE EAST ACROSS THE MS AND TN VALLEY REGIONS BY TUESDAY NIGHT NIGHT...SHEARING OUT AS IT CROSSES THE CAROLINAS ON WEDNESDAY. AS PRECIP SPREADS INTO THE AREA ON THE HEELS OF WEAK HIGH PRESSURE LATE TUESDAY NIGHT...ANOTHER CAD AIRMASS SHOULD DEVELOP OVER THE PIEDMONT. MODELS CONTINUE TO DIFFER REGARDING THE TRACK OF THE ASSOCIATED SURFACE LOW ALONG A STALLED OUT FRONTAL ZONE DRAPED ACROSS THE GULF/SOUTHEAST COAST. THE NAM CONTINUES TO BE THE NORTHERN OUTLIER WITH A LOW TRACK WEST OF THE MOUNTAINS. THE ECMWF APPEARS MORE REALISTIC WITH A TRACK ACROSS GA/SC TOWARD THE NC COAST. THE GFS SOMEWHERE IN BETWEEN TRACKING THE LOW TOWARD THE PIEDMONT...THEN JUMPING ACROSS THE EXPECTED CAD AIRMASS TO THE VA COAST. FAVORING A SOUTHERN TRACK OF THE LOW...THE BEST FOCUS OF DEEP MOISTURE AND LOW LEVEL CONVERGENCE WILL BE ACROSS SC TO SOUTHEAST NC...WHERE MODELS GIVE ONE HALF TO NEAR ONE INCH OF QPF IN TOTAL. AHEAD OF THE SHORTWAVE...MODELS SUGGEST A PLUME A STEEP MID LEVEL LAPSE RATES IN EXCESS OF -6.5 C/KM WITH A TRAJECTORY ACROSS CENTRAL NC. MODEST UPPER LEVEL FORCING FROM THE VORT MAX/LEFT EXIT REGION OF THE STJ...COMBINED WITH STRENGTHENING ISENTROPIC ACCENT IN THE LOW LEVELS...COULD LEAD TO A CHANCE OF THUNDER WEDNESDAY AFTERNOON. POPS WILL BE INCREASED TO ABOVE 80 PERCENT WITH THE HIGHEST VALUES SOUTH WEDNESDAY MORNING. HIGHS IN THE 40S TO POSSIBLY LOWER 50S IN THE SOUTHEAST. WESTERLY FLOW AND COLD/DRY ADVECTION IN THE WAKE OF THE DEPARTING SYSTEM SHOULD HELP TO SCOUR SOME OF THE LINGERING LOW CLOUDS WEDNESDAY NIGHT. LOWS IN THE LOW TO MID 30S. TEMPS SHOULD CLIMB BACK TO AROUND NORMAL ON THURSDAY WITH A LIGHT SOUTHWESTERLY WIND DEVELOPING AS HEIGHTS SLOWLY BEGIN TO FALL OVER THE CENTRAL US. HIGHS 52-57. LOWS THURSDAY NIGHT IN THE LOW TO MID 30S && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 310 PM MONDAY... MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON THE LONGWAVE PATTERN THROUGH THE WEEKEND...WITH RIDGING OVER THE WESTERN US AND A DEEP TROUGH DEVELOPING OVER THE EASTERN US. DETAILS REGARDING THE STRENGTH AND TIMING SHORTWAVES ROTATING INTO THE EAST COAST TROUGH REMAIN SOMEWHAT UNCERTAIN...BUT MODELS CURRENTLY PROJECT A WEAKER TROUGH AND COLD FRONTAL PASSAGE FRIDAY... AND A MORE SUBSTANTIAL TROUGH ARRIVING SATURDAY/SATURDAY NIGHT. BASED ON THE ECMWF AND A CONSENSUS OF GEFS SOLUTIONS...HPC CONTINUES TO FAVOR CYCLOGENESIS OFF THE MID-ATLANTIC COAST SATURDAY NIGHT...SUPPORTING LESS IMPACT OVER THE CAROLINAS. HOWEVER...EVEN WITH RUN-TO-RUN INCONSISTENCIES IN THE GFS/ECMWF...MODELS SUGGEST THE UPPER TROUGH MAY BE STRONG ENOUGH TO OVERCOME THE RELATIVELY DRY AIR OVER CENTRAL NC AND PRODUCE SOME LIGHT QPF. FORECAST LOW LEVEL THICKNESSES PLUMMET WELL BELOW 1300M WITH THE SECOND TROUGH ON SATURDAY....SO CONFIDENCE IS MODERATELY HIGH IN THERMAL PROFILES WILL BECOME FAVORABLE FOR SNOW SHOWERS. THE MAIN QUESTION WILL BE MOISTURE AVAILABILITY OR GENERATION FROM THE TROUGH....BUT THERE HAS BEEN ENOUGH CONSISTENCY IN THE MODELS TO INTRODUCE A SLIGHT CHANCE OF RAIN OR SNOW SHOWERS INTO THE FORECAST SATURDAY EVENING/NIGHT. TEMPS WILL BE TWO TO THREE CATEGORIES BELOW NORMAL SATURDAY AND ESPECIALLY SUNDAY. BEYOND SUNDAY...MODELS SHOW A RIDGE BUILDING EASTWARD ACROSS THE CENTRAL PORTION OF THE COUNTRY EARLY NEXT WEEK WITH A MODERATING TREND AND DRY CONDITIONS. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 120 PM TUESDAY... LIFR CONDITIONS WILL PERSIST FOR ANOTHER FEW HOURS AT INT/GSO... WHILE IFR/MVFR CIGS WITH VFR VSBYS WILL HOLD ELSEWHERE. A WEDGE BOUNDARY REMAINS TO THE SE OF INT/GSO... AND THE LIFR CIGS AND VSBYS AROUND 1 SM HAVE BUDGED LITTLE SO FAR TODAY. EXPECT CIGS TO SLOWLY LIFT EVERYWHERE BUT IMPROVE TO NO BETTER THAN MVFR THROUGH 23Z. CIGS ARE EXPECTED TO RISE TO VFR 01Z-04Z AS A COLD FRONT MOVES EAST THROUGH THE AREA... AND SWRLY SURFACE WINDS SHIFT AROUND TO WSW THEN FROM THE WEST AS A COLD FRONT MOVES THROUGH THE AREA... BEFORE SETTLING JUST TO OUR SOUTH OVERNIGHT. WINDS WILL APPROACH LLWS CRITERIA THROUGH THIS AFTERNOON AS SPEEDS AT 2 THOUSAND FT AGL WILL REMAIN FROM THE SW AT 35-40 KTS... BUT THE EXIT OF THE LOW LEVEL JET WILL CAUSE WINDS ALOFT TO DECREASE TO 25-35 KTS BY 00Z. THE INCREASING WINDS WITH HEIGHT MAY STILL CAUSE ISSUES WITH MECHANICAL TURBULENCE THROUGH THIS EVENING HOWEVER. VFR CIGS WILL HOLD FROM AROUND MIDNIGHT THROUGH TUESDAY MORNING AS WEAK HIGH PRESSURE BUILDS IN. LOOKING BEYOND 18Z TUESDAY... VFR CIGS WILL HOLD INTO TUESDAY EVENING BUT THEN DROP BACK DOWN TO IFR/LIFR OVERNIGHT AS A WAVE OF LOW PRESSURE TRACKS ALONG THE FRONT STALLED JUST TO OUR SOUTH. THESE POOR AVIATION CONDITIONS SHOULD HOLD THROUGH WEDNESDAY BEFORE IMPROVING TO VFR WEDNESDAY EVENING AS THE LOW EXITS. VFR CONDITIONS WILL THEN HOLD UNTIL SATURDAY... WHEN WE COULD SEE ANOTHER STORM SYSTEM BRINGING SUB-VFR CONDITIONS. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...SMITH LONG TERM...SMITH AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
245 PM EST MON FEB 11 2013 .SYNOPSIS... A COLD FRONT WILL CROSS THE REGION THIS EVENING BEFORE SETTLING JUST TO OUR SOUTH LATE TONIGHT. WEAK HIGH PRESSURE WILL MOVE IN LATE TONIGHT THROUGH TUESDAY. A LOW PRESSURE SYSTEM WILL TRACK ALONG THE FRONT TUESDAY NIGHT AND WEDNESDAY... BRINGING UNSETTLED WEATHER. && .NEAR TERM /THROUGH TUESDAY NIGHT/... AS OF 245 PM MONDAY... THROUGH TONIGHT: AS EXPECTED... THE WEDGE AIR MASS OVER THE TRIAD REGION HAS BEEN VERY TOUGH TO DISLODGE... AS EARLY AFTERNOON TEMPS REMAIN IN THE LOWER 50S WITH FOG AND VERY LOW STRATUS HOLDING ON... WHILE READINGS ARE MOSTLY IN THE 60S ELSEWHERE. SW WINDS JUST OFF THE SURFACE (AT 1-2 KFT AGL) ARE NOT QUITE AS STRONG AS THEY WERE THIS MORNING WITH THE DEPARTURE OF THE LOW LEVEL JET TO THE EAST BUT THEY CONTINUE TO PULL IN ENOUGH WARM AIR ALOFT SUCH THAT THE SURFACE-BASED STABLE LAYER IS REINFORCED VIA DIFFERENTIAL TEMP ADVECTION IN THE VERTICAL... DESPITE THE LACK OF A FEED OF COOL AIR AT THE SURFACE. AS SUCH... WE MAY SEE A MUTED FORM OF THIS WEDGE AIR MASS HANG IN OVER THE TRIAD THROUGH THIS EVENING... UNTIL THE COLD FRONT FINALLY SWEEPS THROUGH. LATEST CONVECTION-ALLOWING MODEL RUNS INCLUDING THE HRRR AND HIGH-RES WRF-NMM AND WRF-ARW SHOW WEAK LOW PRESSURE OVER NRN GA TRACKING ALONG THE FRONT AND IS ASSOCIATED WITH THE UPSTREAM PRECIP BAND NOW ACROSS NRN GA AND UPSTATE SC STREAMING TO THE ENE ACROSS THE FAR SRN/SE CWA... HOWEVER PREFRONTAL CONVECTION TO THE SSE OVER SRN GA MAY INTERRUPT THE POLEWARD MOISTURE TRANSPORT SUCH THAT WE`LL ONLY SEE LIGHT AMOUNTS AT MOST. WILL HOLD ONTO THE LOW CHANCE POPS OVER THE FAR SRN AND SE CWA THROUGH THIS EVENING... WITH DRY WEATHER OVERNIGHT. A SUBTLE MID LEVEL WAVE CONNECTED TO THE VORTEX CROSSING FAR SE ONTARIO AND SRN QUEBEC WILL CROSS THE MIDATLANTIC REGION LATER TONIGHT... FLATTENING THE MID LEVEL FLOW AND PROPELLING THE SURFACE FRONT TO OUR SOUTHEAST. THIS FLOW WILL REMAIN QUITE SWIFT TONIGHT... 80-90 KTS AT 500 MB... WITH PLENTY OF MOISTURE AT 310K-320K... SO EXPECT ABUNDANT MID LEVEL CLOUDS TO STREAM ACROSS THE AREA THROUGH THE NIGHT. LOWS 39-47. FOR TUESDAY/TUESDAY NIGHT: WILL SEE A BRIEF RESPITE IN THE ACTIVE PATTERN ON TUESDAY BEFORE THE RAIN RAMPS BACK UP TUESDAY EVENING. THE FRONT WILL HOLD TO OUR SOUTH WITH WEAK HIGH PRESSURE BUILDING OVER THE REGION. MID LEVEL FLOW REMAINS FAST (NEAR 80 KTS) OVER THE REGION BUT WILL BECOME GENTLY ANTICYCLONIC FOR A TIME... AS THE DEEP TROUGH LOCATED OVER THE FOUR CORNERS REGION STARTS TO KICK EASTWARD INTO THE SRN PLAINS. WE`LL LIKELY SEE PARTLY SUNNY SKIES GIVE WAY TO GREATER SUNSHINE TOWARD AFTERNOON... PARTICULARLY ACROSS THE NORTHERN CWA. LOW LEVEL THICKNESSES AS WELL AS THE LOW LEVEL THERMAL STRUCTURE SUPPORT HIGHS IN THE UPPER 50S TO LOWER 60S. THE MID LEVEL TROUGH SHIFTS THROUGH THE MID MISS VALLEY AS A POSITIVELY-TILTED WEAKENING WAVE... AND MODELS ALL AGREE ON A RAPID INCREASE IN DEEP MOIST ISENTROPIC UPGLIDE FROM 285K-305K OUT AHEAD OVER THE CAROLINAS. SIMILAR TO LAST NIGHT`S RAINFALL PATTERN... WITH THE FRONT LIKELY TO STILL HOLD SOUTH OF THE NC BORDER THROUGH TUESDAY NIGHT AND WITH INCREASING LAPSE RATES AND INSTABILITY OVER MS/AL/GA... WE SHOULD SEE THE GREATEST RISK OF HEAVY PRECIP CONFINED TO ALONG AND SOUTH OF THE BORDER. WITH A GOOD CHANCE OF A CONVECTIVE BAND WELL TO OUR SOUTH AND SW TUESDAY NIGHT... MOISTURE TRANSPORT MAY BE SUFFICIENTLY REDUCED TO GREATLY LIMIT AMOUNTS AND COVERAGE OVER NRN NC. NEVERTHELESS... GIVEN THE RESURGENCE OF 1+ INCH PRECIP WATER INTO THE SRN AND ERN CWA OVERNIGHT... CONFIDENCE IS HIGH ENOUGH FOR CATEGORICAL POPS IN THE SRN/SE CWA... TRENDING TO GOOD CHANCE NEAR THE VA BORDER. AMOUNTS ALONG/NORTH OF HIGHWAY 64 MAY BE LESS THAN A TENTH... WHILE AREAS NEAR THE SC BORDER COULD SEE A HALF INCH OR MORE. LOWS 40-46. -GIH && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... AS OF 305 AM MONDAY... WEDNESDAY...EXPECT WIDESPREAD RAIN TO OVERSPREAD CENTRAL NC EARLY WED AND CONTINUE WELL INTO THE AFTERNOON. THE PRECIP AND OVERCAST SKIES WILL RESULT IN BELOW NORMAL TEMPS WITH MAX TEMPS HOLDING INT EH 40S ACROSS MOST OF THE PIEDMONT...AND THE LOWER 50S IN THE FAR SOUTH-SE. WEDNESDAY NIGHT...S/W CROSSES THE REGION IN THE EVENING THEN EXITS THE COAST. DRIER WNW FLOW BEHIND THIS SYSTEM AS WELL AS SUBSIDENCE WILL AID TO DISSIPATE CLOUD COVERAGE NW-SE DURING THE OVERNIGHT HOURS. RESIDUAL MOISTURE MAY RESULT IN SOME AREAS OF FOG BUT CONFIDENCE NOT HIGH ENOUGH AT THIS TIME TO INTRODUCE IN THE FORECAST AS MAY BE ENOUGH MIXING TO PREVENT FOG FROM DEVELOPING. MIN TEMPS MID-UPPER 30S. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 305 AM MONDAY... THURSDAY INTO FRIDAY...RELATIVELY TRANQUIL WEATHER PATTERN ANTICIPATED AS BROAD TROUGH OVER THE EASTERN U.S. WILL CAUSE A WLY FLOW THROUGH THE COLUMN OVER CENTRAL NC. THIS USUALLY YIELDS DRY WEATHER WITH MILD TEMPS. LOW LEVEL THICKNESSES A SHADE ABOVE NORMAL THU AND NEAR NORMAL FRI BUT WLY FLOW USUALLY ADDS ADDITIONAL WARMING. AFTERNOON TEMPS IN THE 50S BOTH DAYS...APPROACHING 60 N THE FAR SOUTH FRI. BROAD UPPER TROUGH OVER EASTERN U.S. WILL UNDERGO AMPLIFICATION SATURDAY INTO SUNDAY AS PACIFIC ENERGY IS SHUNTED WELL NWD INTO ALASKA AND BRITISH COLUMBIA IN RESPONSE TO A STOUT UPPER LEVEL RIDGE OVER THE WESTERN U.S. THIS ENERGY DIVES ON SEWD INTO THE NORTH CENTRAL U.S. INITIATING THE AMPLIFICATION OF THE TROUGH. THIS WILL CAUSE A MODIFIED ARCTIC AIR MASS TO SPREAD SEWD ACROSS MUCH OF THE EASTERN U.S. THIS WEEKEND. THE LEADING EDGE OF THIS COLDER AIR WILL SPREAD ACROSS CENTRAL NC FRI NIGHT INTO SATURDAY. MODEL GUIDANCE CONTINUES TO EXHIBIT POSSIBLE SURFACE CYCLOGENESIS ASSOCIATED WITH THIS AMPLIFICATION OFF THE EASTERN SEABOARD IN VICINITY OF THE MID ATLANTIC COAST NWD TO NEW ENGLAND. CONSIDERING THE STRENGTH OF THE DISTURBANCES ALOFT...MAY BE ENOUGH TO TRIGGER SCATTERED SHOWERS ACROSS CENTRAL NC SATURDAY INTO SATURDAY EVENING. PARTIAL THICKNESSES AND FORECAST GFS BUFKIT SOUNDINGS SUGGEST THAT SNOW SHOWERS WOULD BE FAVORED OVER RAIN SHOWERS BUT MODELS MAY BE COOLING OFF THE COLUMN TOO QUICKLY. SINCE WE ARE TALKING ABOUT DAY 6...PREFER TO MAINTAIN A SLIGHT CHANCE POP FOR NOW AND KEEP PRECIP ALL LIQUID. HOWEVER DID BUMP UP CLOUDINESS A TAD AND LOWERED MAX TEMPS SATURDAY 2-3 DEGREES FROM THE PREVIOUS FORECAST. MAX TEMPS SATURDAY IN THE 40S TO NEAR 50 SOUTHEAST. IF PRECIP MORE EXTENSIVE THAN CURRENT THINKING...MAX TEMPS COULD BE TOO WARM BY AS MUCH AS 5-6 DEGREES. BULK OF COLDER AIR WILL SETTLE OVER THE REGION SUNDAY WITH MAX TEMPS 10-14 DEGREES BELOW NORMAL. MIN TEMPS SUN MORNING IN THE 20S. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 120 PM TUESDAY... LIFR CONDITIONS WILL PERSIST FOR ANOTHER FEW HOURS AT INT/GSO... WHILE IFR/MVFR CIGS WITH VFR VSBYS WILL HOLD ELSEWHERE. A WEDGE BOUNDARY REMAINS TO THE SE OF INT/GSO... AND THE LIFR CIGS AND VSBYS AROUND 1 SM HAVE BUDGED LITTLE SO FAR TODAY. EXPECT CIGS TO SLOWLY LIFT EVERYWHERE BUT IMPROVE TO NO BETTER THAN MVFR THROUGH 23Z. CIGS ARE EXPECTED TO RISE TO VFR 01Z-04Z AS A COLD FRONT MOVES EAST THROUGH THE AREA... AND SWRLY SURFACE WINDS SHIFT AROUND TO WSW THEN FROM THE WEST AS A COLD FRONT MOVES THROUGH THE AREA... BEFORE SETTLING JUST TO OUR SOUTH OVERNIGHT. WINDS WILL APPROACH LLWS CRITERIA THROUGH THIS AFTERNOON AS SPEEDS AT 2 THOUSAND FT AGL WILL REMAIN FROM THE SW AT 35-40 KTS... BUT THE EXIT OF THE LOW LEVEL JET WILL CAUSE WINDS ALOFT TO DECREASE TO 25-35 KTS BY 00Z. THE INCREASING WINDS WITH HEIGHT MAY STILL CAUSE ISSUES WITH MECHANICAL TURBULENCE THROUGH THIS EVENING HOWEVER. VFR CIGS WILL HOLD FROM AROUND MIDNIGHT THROUGH TUESDAY MORNING AS WEAK HIGH PRESSURE BUILDS IN. LOOKING BEYOND 18Z TUESDAY... VFR CIGS WILL HOLD INTO TUESDAY EVENING BUT THEN DROP BACK DOWN TO IFR/LIFR OVERNIGHT AS A WAVE OF LOW PRESSURE TRACKS ALONG THE FRONT STALLED JUST TO OUR SOUTH. THESE POOR AVIATION CONDITIONS SHOULD HOLD THROUGH WEDNESDAY BEFORE IMPROVING TO VFR WEDNESDAY EVENING AS THE LOW EXITS. VFR CONDITIONS WILL THEN HOLD UNTIL SATURDAY... WHEN WE COULD SEE ANOTHER STORM SYSTEM BRINGING SUB-VFR CONDITIONS. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...WSS LONG TERM...WSS AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
125 PM EST MON FEB 11 2013 .SYNOPSIS... A WARM FRONT WILL CONTINUE MOVING NORTHWARD THROUGH THE AREA TODAY. A COLD FRONT WILL CROSS THE REGION THIS EVENING BEFORE SETTLING JUST TO OUR SOUTH... THEN WEAK HIGH PRESSURE WILL MOVE IN LATE TONIGHT THROUGH TUESDAY. A LOW PRESSURE SYSTEM WILL TRACK ALONG THE FRONT AND AFFECT THE AREA ON WEDNESDAY. && .NEAR TERM /THROUGH TUESDAY/... AS OF 950 AM MONDAY... REST OF TODAY: MAIN CONCERNS THIS MORNING ARE DEALING WITH THE DEPARTING RAIN... WIDELY VARYING TEMPS... AND WIND. WEDGE REGIME REMAINS WELL-ENTRENCHED OVER THE FAR NRN AND NW PIEDMONT... BISECTING THE TRIAD REGION WITH 9 AM TEMPS IN THE UPPER 50S IN ASHEBORO WHILE LOWER 40S HOLD AT LEXINGTON WITH FOG/STRATUS AND VERY LIGHT TO CALM AIR. THE 12Z GSO SOUNDING SHOWS A FORMIDABLE STABLE LAYER (+4C DIFFERENTIAL FROM SURFACE TO WARM NOSE ALOFT) WITH DEEP SATURATION... AND EVEN OUTSIDE OF THIS DEFINED WEDGE... DESPITE THE MILDER TEMPS IN THE 50S... THE LOW LEVELS (UNDER 900 MB) REMAIN NEUTRAL TO SLIGHTLY STABLE AS NOTED BY RECENT AMDAR AIRCRAFT SOUNDINGS NEAR RDU. WINDS HERE ARE BEGINNING TO PICK UP OUT OF THE SOUTH AND SW THOUGH... INDICATING THAT IMPROVED LOW LEVEL MIXING IS IMMINENT. THE WIDESPREAD LIGHT RAIN IS ON ITS WAY OUT A BIT MORE QUICKLY THAN EARLIER ANTICIPATED... HOWEVER WITH BLENDED TPW IMAGERY SHOWING PRECIP WATER VALUES OVER 200 PERCENT OF NORMAL ACROSS THE ENTIRE REGION... THE RISK OF PATCHY SHOWERS WILL REMAIN FOR ANOTHER SEVERAL HOURS AS THE MOIST COLUMN WILL STAY VULNERABLE TO EVEN SUBTLE FORCING FOR ASCENT. WILL HOLD ONTO SMALL POPS MAINLY S/E OF THE TRIAD INTO THE AFTERNOON. LOW CLOUDS SHOULD HOLD IN EVERYWHERE UNTIL MID AFTERNOON WITH THE CONTINUED LOW-MID LEVEL FLOW FROM THE SW ELIMINATING THE POTENTIAL FOR SIGNIFICANT DOWNSLOPE DRYING UNTIL LATE... WHEN THE MID LEVEL PERTURBATION NOW OVER NW NC MOVES OFF THE COAST. TEMPS ARE ALWAYS TOUGH TO GAUGE IN THESE WEDGE SITUATIONS ESPECIALLY WHEN THERE IS NO LONGER A FEED OF LOW LEVEL DRY AIR TO MAINTAIN THE STABLE POOL. ALL FINE-RESULTION GUIDANCE INCLUDING THE LOCAL WRF AND HRRR FAVORS A MIXING-OUT OF THE REMAINING WEDGE OVER OUR NW CWA BY EARLY AFTERNOON... ALTHOUGH THE ABUNDANT THICK CLOUDS FOR MUCH OF THE DAY WILL CUT DOWN ON WARMING ALL ACROSS THE AREA. NEVERTHELESS.... ANOMALOUSLY WARM THICKNESSES WILL RISE FURTHER THIS AFTERNOON... AND STILL EXPECT HIGHS IN THE MID 60S TO NEAR 70 OVER MUCH OF THE CWA EXCEPT FOR NEAR 60 IN THE NW CORNER. SINCE WE WON`T FULLY MIX UP BEYOND 900 MB UNTIL LATE IN THE DAY... WHEN THE 50-60 KT LOW LEVEL JET WILL HAVE EXITED... OUR WIND GUSTS WILL REMAIN WELL BELOW ADVISORY THRESHOLD... YET WE SHOULD STILL SEE GUSTS BECOME MORE FREQUENT AND HIGHER THIS AFTERNOON ESPECIALLY OUTSIDE THE DECAYING WEDGE REGION. GUSTS SHOULD EXCEED 20-25 KTS PERIODICALLY. -GIH TONIGHT AND TUESDAY: SURFACE COLD FRONT IS EXPECTED TO QUICKLY MOVE ACROSS THE AREA LATE TODAY INTO THIS EVENING WITH THE LOW LEVEL AIRMASS COMPLETELY SCOURING OUT AS IT MOVES THROUGH. HOWEVER... WE WILL KEEP A LEAST SOME MID AND HIGH LEVEL CLOUD COVER... ESPECIALLY ACROSS THE SOUTH.... WHILE THE SURFACE FRONT STALLS TO THE SOUTH OF THE AREA. EXPECT LOW TEMPS TONIGHT TO RANGE FROM AROUND 40 NW TO UPPER 40S SE... WITH A WEST TO NORTHWESTERLY BREEZE AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION. TUESDAY WILL START OFF WITH QUITE WEATHER. HOWEVER... A SOUTHERN STREAM DISTURBANCE WILL BEGIN APPROACHING THE REGION FROM THE SOUTHWEST ON TUESDAY... SPREADING MORE CLOUDS INTO THE AREA AND PERHAPS SOME LIGHT RAIN ACROSS THE FAR SOUTHWEST LATE IN THE DAY. HIGH TEMPS ARE AGAIN EXPECTED TO BE ABOVE NORMAL AS THE SYSTEM APPROACHES FROM THE SOUTH AND SURFACE WINDS QUICKLY SWING BACK AROUND TO WSW TO SOUTHWESTERLY IN ADVANCE OF THE DISTURBANCE. THUS... WILL GO WITH HIGHS IN THE LOWER TO MID 60S. -BSD && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... AS OF 305 AM MONDAY... TUESDAY NIGHT THROUGH WEDNESDAY NIGHT... NEXT LOW PRESSURE SYSTEM IN THE ACTIVE SOUTHERN STREAM PROJECTED TO TRAVERSE THE SOUTHERN PLAINS INTO THE LOWER MS VALLEY LATE TUE-TUE NIGHT. THIS WEATHER SYSTEM WILL INDUCE THE FORMATION OF A SURFACE LOW ON THE STALLED FRONT OVER THE NORTHERN GULF COAST BY LATE TUESDAY. THE 00Z GFS TAKES THIS SURFACE WAVE NEWD UP THE SOUTHERN APPALACHIANS THEN EWD ACROSS THE NC-VA PIEDMONT. 00Z ECMWF FITS INTO THE CLASSICAL MODEL WITH THE WAVE PROGRESSING ENE ALONG A STALLED SURFACE BOUNDARY ACROSS SOUTHERN AL-SOUTHERN GA THEN OFF THE CAROLINA COASTS WHERE IT INTENSIFIES IN THE FAVORABLE BAROCLINIC ZONE CAUSED BY THE GULF STREAM. INCREASING SLY FLOW AHEAD OF THE SURFACE LOW WILL CAUSE AN OVERRUNNING PRECIP EVENT ACROSS CENTRAL NC LATE TUESDAY NIGHT THROUGH WEDNESDAY EVENING. THE INCREASING MOISTURE WILL ALSO BE LIFTED BY NOT ONLY THE MID-UPPER LEVEL S/W BUT ALSO FROM A FAVORABLE JET CONFIGURATION WITH CENTRAL NC IN THE NOSE OF 140+ KT JET. THUS...EXPECT WIDESPREAD RAIN TO OVERSPREAD CENTRAL NC EARLY WED AND CONTINUE WELL INTO THE AFTERNOON. THE PRECIP AND OVERCAST SKIES WILL RESULT IN BELOW NORMAL TEMPS WITH MAX TEMPS HOLDING INT EH 40S ACROSS MOST OF THE PIEDMONT...AND THE LOWER 50S IN THE FAR SOUTH-SE. WEDNESDAY NIGHT...S/W CROSSES THE REGION IN THE EVENING THEN EXITS THE COAST. DRIER WNW FLOW BEHIND THIS SYSTEM AS WELL AS SUBSIDENCE WILL AID TO DISSIPATE CLOUD COVERAGE NW-SE DURING THE OVERNIGHT HOURS. RESIDUAL MOISTURE MAY RESULT IN SOME AREAS OF FOG BUT CONFIDENCE NOT HIGH ENOUGH AT THIS TIME TO INTRODUCE IN THE FORECAST AS MAY BE ENOUGH MIXING TO PREVENT FOG FROM DEVELOPING. MIN TEMPS MID-UPPER 30S. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 305 AM MONDAY... THURSDAY INTO FRIDAY...RELATIVELY TRANQUIL WEATHER PATTERN ANTICIPATED AS BROAD TROUGH OVER THE EASTERN U.S. WILL CAUSE A WLY FLOW THROUGH THE COLUMN OVER CENTRAL NC. THIS USUALLY YIELDS DRY WEATHER WITH MILD TEMPS. LOW LEVEL THICKNESSES A SHADE ABOVE NORMAL THU AND NEAR NORMAL FRI BUT WLY FLOW USUALLY ADDS ADDITIONAL WARMING. AFTERNOON TEMPS IN THE 50S BOTH DAYS...APPROACHING 60 N THE FAR SOUTH FRI. BROAD UPPER TROUGH OVER EASTERN U.S. WILL UNDERGO AMPLIFICATION SATURDAY INTO SUNDAY AS PACIFIC ENERGY IS SHUNTED WELL NWD INTO ALASKA AND BRITISH COLUMBIA IN RESPONSE TO A STOUT UPPER LEVEL RIDGE OVER THE WESTERN U.S. THIS ENERGY DIVES ON SEWD INTO THE NORTH CENTRAL U.S. INITIATING THE AMPLIFICATION OF THE TROUGH. THIS WILL CAUSE A MODIFIED ARCTIC AIR MASS TO SPREAD SEWD ACROSS MUCH OF THE EASTERN U.S. THIS WEEKEND. THE LEADING EDGE OF THIS COLDER AIR WILL SPREAD ACROSS CENTRAL NC FRI NIGHT INTO SATURDAY. MODEL GUIDANCE CONTINUES TO EXHIBIT POSSIBLE SURFACE CYCLOGENESIS ASSOCIATED WITH THIS AMPLIFICATION OFF THE EASTERN SEABOARD IN VICINITY OF THE MID ATLANTIC COAST NWD TO NEW ENGLAND. CONSIDERING THE STRENGTH OF THE DISTURBANCES ALOFT...MAY BE ENOUGH TO TRIGGER SCATTERED SHOWERS ACROSS CENTRAL NC SATURDAY INTO SATURDAY EVENING. PARTIAL THICKNESSES AND FORECAST GFS BUFKIT SOUNDINGS SUGGEST THAT SNOW SHOWERS WOULD BE FAVORED OVER RAIN SHOWERS BUT MODELS MAY BE COOLING OFF THE COLUMN TOO QUICKLY. SINCE WE ARE TALKING ABOUT DAY 6...PREFER TO MAINTAIN A SLIGHT CHANCE POP FOR NOW AND KEEP PRECIP ALL LIQUID. HOWEVER DID BUMP UP CLOUDINESS A TAD AND LOWERED MAX TEMPS SATURDAY 2-3 DEGREES FROM THE PREVIOUS FORECAST. MAX TEMPS SATURDAY IN THE 40S TO NEAR 50 SOUTHEAST. IF PRECIP MORE EXTENSIVE THAN CURRENT THINKING...MAX TEMPS COULD BE TOO WARM BY AS MUCH AS 5-6 DEGREES. BULK OF COLDER AIR WILL SETTLE OVER THE REGION SUNDAY WITH MAX TEMPS 10-14 DEGREES BELOW NORMAL. MIN TEMPS SUN MORNING IN THE 20S. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 120 PM TUESDAY... LIFR CONDITIONS WILL PERSIST FOR ANOTHER FEW HOURS AT INT/GSO... WHILE IFR/MVFR CIGS WITH VFR VSBYS WILL HOLD ELSEWHERE. A WEDGE BOUNDARY REMAINS TO THE SE OF INT/GSO... AND THE LIFR CIGS AND VSBYS AROUND 1 SM HAVE BUDGED LITTLE SO FAR TODAY. EXPECT CIGS TO SLOWLY LIFT EVERYWHERE BUT IMPROVE TO NO BETTER THAN MVFR THROUGH 23Z. CIGS ARE EXPECTED TO RISE TO VFR 01Z-04Z AS A COLD FRONT MOVES EAST THROUGH THE AREA... AND SWRLY SURFACE WINDS SHIFT AROUND TO WSW THEN FROM THE WEST AS A COLD FRONT MOVES THROUGH THE AREA... BEFORE SETTLING JUST TO OUR SOUTH OVERNIGHT. WINDS WILL APPROACH LLWS CRITERIA THROUGH THIS AFTERNOON AS SPEEDS AT 2 THOUSAND FT AGL WILL REMAIN FROM THE SW AT 35-40 KTS... BUT THE EXIT OF THE LOW LEVEL JET WILL CAUSE WINDS ALOFT TO DECREASE TO 25-35 KTS BY 00Z. THE INCREASING WINDS WITH HEIGHT MAY STILL CAUSE ISSUES WITH MECHANICAL TURBULENCE THROUGH THIS EVENING HOWEVER. VFR CIGS WILL HOLD FROM AROUND MIDNIGHT THROUGH TUESDAY MORNING AS WEAK HIGH PRESSURE BUILDS IN. LOOKING BEYOND 18Z TUESDAY... VFR CIGS WILL HOLD INTO TUESDAY EVENING BUT THEN DROP BACK DOWN TO IFR/LIFR OVERNIGHT AS A WAVE OF LOW PRESSURE TRACKS ALONG THE FRONT STALLED JUST TO OUR SOUTH. THESE POOR AVIATION CONDITIONS SHOULD HOLD THROUGH WEDNESDAY BEFORE IMPROVING TO VFR WEDNESDAY EVENING AS THE LOW EXITS. VFR CONDITIONS WILL THEN HOLD UNTIL SATURDAY... WHEN WE COULD SEE ANOTHER STORM SYSTEM BRINGING SUB-VFR CONDITIONS. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD/BSD SHORT TERM...WSS LONG TERM...WSS AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
950 AM EST MON FEB 11 2013 .SYNOPSIS... A WARM FRONT WILL CONTINUE MOVING NORTHWARD THROUGH THE AREA TODAY. A COLD FRONT WILL CROSS THE REGION THIS EVENING BEFORE SETTLING JUST TO OUR SOUTH... THEN WEAK HIGH PRESSURE WILL MOVE IN LATE TONIGHT THROUGH TUESDAY. A LOW PRESSURE SYSTEM WILL TRACK ALONG THE FRONT AND AFFECT THE AREA ON WEDNESDAY. && .NEAR TERM /THROUGH TUESDAY/... AS OF 950 AM MONDAY... REST OF TODAY: MAIN CONCERNS THIS MORNING ARE DEALING WITH THE DEPARTING RAIN... WIDELY VARYING TEMPS... AND WIND. WEDGE REGIME REMAINS WELL-ENTRENCHED OVER THE FAR NRN AND NW PIEDMONT... BISECTING THE TRIAD REGION WITH 9 AM TEMPS IN THE UPPER 50S IN ASHEBORO WHILE LOWER 40S HOLD AT LEXINGTON WITH FOG/STRATUS AND VERY LIGHT TO CALM AIR. THE 12Z GSO SOUNDING SHOWS A FORMIDABLE STABLE LAYER (+4C DIFFERENTIAL FROM SURFACE TO WARM NOSE ALOFT) WITH DEEP SATURATION... AND EVEN OUTSIDE OF THIS DEFINED WEDGE... DESPITE THE MILDER TEMPS IN THE 50S... THE LOW LEVELS (UNDER 900 MB) REMAIN NEUTRAL TO SLIGHTLY STABLE AS NOTED BY RECENT AMDAR AIRCRAFT SOUNDINGS NEAR RDU. WINDS HERE ARE BEGINNING TO PICK UP OUT OF THE SOUTH AND SW THOUGH... INDICATING THAT IMPROVED LOW LEVEL MIXING IS IMMINENT. THE WIDESPREAD LIGHT RAIN IS ON ITS WAY OUT A BIT MORE QUICKLY THAN EARLIER ANTICIPATED... HOWEVER WITH BLENDED TPW IMAGERY SHOWING PRECIP WATER VALUES OVER 200 PERCENT OF NORMAL ACROSS THE ENTIRE REGION... THE RISK OF PATCHY SHOWERS WILL REMAIN FOR ANOTHER SEVERAL HOURS AS THE MOIST COLUMN WILL STAY VULNERABLE TO EVEN SUBTLE FORCING FOR ASCENT. WILL HOLD ONTO SMALL POPS MAINLY S/E OF THE TRIAD INTO THE AFTERNOON. LOW CLOUDS SHOULD HOLD IN EVERYWHERE UNTIL MID AFTERNOON WITH THE CONTINUED LOW-MID LEVEL FLOW FROM THE SW ELIMINATING THE POTENTIAL FOR SIGNIFICANT DOWNSLOPE DRYING UNTIL LATE... WHEN THE MID LEVEL PERTURBATION NOW OVER NW NC MOVES OFF THE COAST. TEMPS ARE ALWAYS TOUGH TO GAUGE IN THESE WEDGE SITUATIONS ESPECIALLY WHEN THERE IS NO LONGER A FEED OF LOW LEVEL DRY AIR TO MAINTAIN THE STABLE POOL. ALL FINE-RESULTION GUIDANCE INCLUDING THE LOCAL WRF AND HRRR FAVORS A MIXING-OUT OF THE REMAINING WEDGE OVER OUR NW CWA BY EARLY AFTERNOON... ALTHOUGH THE ABUNDANT THICK CLOUDS FOR MUCH OF THE DAY WILL CUT DOWN ON WARMING ALL ACROSS THE AREA. NEVERTHELESS.... ANOMALOUSLY WARM THICKNESSES WILL RISE FURTHER THIS AFTERNOON... AND STILL EXPECT HIGHS IN THE MID 60S TO NEAR 70 OVER MUCH OF THE CWA EXCEPT FOR NEAR 60 IN THE NW CORNER. SINCE WE WON`T FULLY MIX UP BEYOND 900 MB UNTIL LATE IN THE DAY... WHEN THE 50-60 KT LOW LEVEL JET WILL HAVE EXITED... OUR WIND GUSTS WILL REMAIN WELL BELOW ADVISORY THRESHOLD... YET WE SHOULD STILL SEE GUSTS BECOME MORE FREQUENT AND HIGHER THIS AFTERNOON ESPECIALLY OUTSIDE THE DECAYING WEDGE REGION. GUSTS SHOULD EXCEED 20-25 KTS PERIODICALLY. -GIH TONIGHT AND TUESDAY: SURFACE COLD FRONT IS EXPECTED TO QUICKLY MOVE ACROSS THE AREA LATE TODAY INTO THIS EVENING WITH THE LOW LEVEL AIRMASS COMPLETELY SCOURING OUT AS IT MOVES THROUGH. HOWEVER... WE WILL KEEP A LEAST SOME MID AND HIGH LEVEL CLOUD COVER... ESPECIALLY ACROSS THE SOUTH.... WHILE THE SURFACE FRONT STALLS TO THE SOUTH OF THE AREA. EXPECT LOW TEMPS TONIGHT TO RANGE FROM AROUND 40 NW TO UPPER 40S SE... WITH A WEST TO NORTHWESTERLY BREEZE AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION. TUESDAY WILL START OFF WITH QUITE WEATHER. HOWEVER... A SOUTHERN STREAM DISTURBANCE WILL BEGIN APPROACHING THE REGION FROM THE SOUTHWEST ON TUESDAY... SPREADING MORE CLOUDS INTO THE AREA AND PERHAPS SOME LIGHT RAIN ACROSS THE FAR SOUTHWEST LATE IN THE DAY. HIGH TEMPS ARE AGAIN EXPECTED TO BE ABOVE NORMAL AS THE SYSTEM APPROACHES FROM THE SOUTH AND SURFACE WINDS QUICKLY SWING BACK AROUND TO WSW TO SOUTHWESTERLY IN ADVANCE OF THE DISTURBANCE. THUS... WILL GO WITH HIGHS IN THE LOWER TO MID 60S. -BSD && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... AS OF 305 AM MONDAY... TUESDAY NIGHT THROUGH WEDNESDAY NIGHT... NEXT LOW PRESSURE SYSTEM IN THE ACTIVE SOUTHERN STREAM PROJECTED TO TRAVERSE THE SOUTHERN PLAINS INTO THE LOWER MS VALLEY LATE TUE-TUE NIGHT. THIS WEATHER SYSTEM WILL INDUCE THE FORMATION OF A SURFACE LOW ON THE STALLED FRONT OVER THE NORTHERN GULF COAST BY LATE TUESDAY. THE 00Z GFS TAKES THIS SURFACE WAVE NEWD UP THE SOUTHERN APPALACHIANS THEN EWD ACROSS THE NC-VA PIEDMONT. 00Z ECMWF FITS INTO THE CLASSICAL MODEL WITH THE WAVE PROGRESSING ENE ALONG A STALLED SURFACE BOUNDARY ACROSS SOUTHERN AL-SOUTHERN GA THEN OFF THE CAROLINA COASTS WHERE IT INTENSIFIES IN THE FAVORABLE BAROCLINIC ZONE CAUSED BY THE GULF STREAM. INCREASING SLY FLOW AHEAD OF THE SURFACE LOW WILL CAUSE AN OVERRUNNING PRECIP EVENT ACROSS CENTRAL NC LATE TUESDAY NIGHT THROUGH WEDNESDAY EVENING. THE INCREASING MOISTURE WILL ALSO BE LIFTED BY NOT ONLY THE MID-UPPER LEVEL S/W BUT ALSO FROM A FAVORABLE JET CONFIGURATION WITH CENTRAL NC IN THE NOSE OF 140+ KT JET. THUS...EXPECT WIDESPREAD RAIN TO OVERSPREAD CENTRAL NC EARLY WED AND CONTINUE WELL INTO THE AFTERNOON. THE PRECIP AND OVERCAST SKIES WILL RESULT IN BELOW NORMAL TEMPS WITH MAX TEMPS HOLDING INT EH 40S ACROSS MOST OF THE PIEDMONT...AND THE LOWER 50S IN THE FAR SOUTH-SE. WEDNESDAY NIGHT...S/W CROSSES THE REGION IN THE EVENING THEN EXITS THE COAST. DRIER WNW FLOW BEHIND THIS SYSTEM AS WELL AS SUBSIDENCE WILL AID TO DISSIPATE CLOUD COVERAGE NW-SE DURING THE OVERNIGHT HOURS. RESIDUAL MOISTURE MAY RESULT IN SOME AREAS OF FOG BUT CONFIDENCE NOT HIGH ENOUGH AT THIS TIME TO INTRODUCE IN THE FORECAST AS MAY BE ENOUGH MIXING TO PREVENT FOG FROM DEVELOPING. MIN TEMPS MID-UPPER 30S. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 305 AM MONDAY... THURSDAY INTO FRIDAY...RELATIVELY TRANQUIL WEATHER PATTERN ANTICIPATED AS BROAD TROUGH OVER THE EASTERN U.S. WILL CAUSE A WLY FLOW THROUGH THE COLUMN OVER CENTRAL NC. THIS USUALLY YIELDS DRY WEATHER WITH MILD TEMPS. LOW LEVEL THICKNESSES A SHADE ABOVE NORMAL THU AND NEAR NORMAL FRI BUT WLY FLOW USUALLY ADDS ADDITIONAL WARMING. AFTERNOON TEMPS IN THE 50S BOTH DAYS...APPROACHING 60 N THE FAR SOUTH FRI. BROAD UPPER TROUGH OVER EASTERN U.S. WILL UNDERGO AMPLIFICATION SATURDAY INTO SUNDAY AS PACIFIC ENERGY IS SHUNTED WELL NWD INTO ALASKA AND BRITISH COLUMBIA IN RESPONSE TO A STOUT UPPER LEVEL RIDGE OVER THE WESTERN U.S. THIS ENERGY DIVES ON SEWD INTO THE NORTH CENTRAL U.S. INITIATING THE AMPLIFICATION OF THE TROUGH. THIS WILL CAUSE A MODIFIED ARCTIC AIR MASS TO SPREAD SEWD ACROSS MUCH OF THE EASTERN U.S. THIS WEEKEND. THE LEADING EDGE OF THIS COLDER AIR WILL SPREAD ACROSS CENTRAL NC FRI NIGHT INTO SATURDAY. MODEL GUIDANCE CONTINUES TO EXHIBIT POSSIBLE SURFACE CYCLOGENESIS ASSOCIATED WITH THIS AMPLIFICATION OFF THE EASTERN SEABOARD IN VICINITY OF THE MID ATLANTIC COAST NWD TO NEW ENGLAND. CONSIDERING THE STRENGTH OF THE DISTURBANCES ALOFT...MAY BE ENOUGH TO TRIGGER SCATTERED SHOWERS ACROSS CENTRAL NC SATURDAY INTO SATURDAY EVENING. PARTIAL THICKNESSES AND FORECAST GFS BUFKIT SOUNDINGS SUGGEST THAT SNOW SHOWERS WOULD BE FAVORED OVER RAIN SHOWERS BUT MODELS MAY BE COOLING OFF THE COLUMN TOO QUICKLY. SINCE WE ARE TALKING ABOUT DAY 6...PREFER TO MAINTAIN A SLIGHT CHANCE POP FOR NOW AND KEEP PRECIP ALL LIQUID. HOWEVER DID BUMP UP CLOUDINESS A TAD AND LOWERED MAX TEMPS SATURDAY 2-3 DEGREES FROM THE PREVIOUS FORECAST. MAX TEMPS SATURDAY IN THE 40S TO NEAR 50 SOUTHEAST. IF PRECIP MORE EXTENSIVE THAN CURRENT THINKING...MAX TEMPS COULD BE TOO WARM BY AS MUCH AS 5-6 DEGREES. BULK OF COLDER AIR WILL SETTLE OVER THE REGION SUNDAY WITH MAX TEMPS 10-14 DEGREES BELOW NORMAL. MIN TEMPS SUN MORNING IN THE 20S. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... AS OF 640 AM TUESDAY... 24 HOUR TAF PERIOD: ADVERSE AVIATION CONDITIONS EXPECTED TODAY... WITH SUB-VFR CONDITIONS AND GUSTY WINDS POSSIBLE. LIGHT RAIN AND DRIZZLE ARE FILLING IN ACROSS CENTRAL NC AGAIN THIS MORNING... WITH ALONG WITH A MORE DEFINED IN-SITU COLD AIR DAMMING WEDGE AIRMASS PARKED ACROSS THE AREA. AT KFAY THE WARM FRONT HAS SURGE TO THE NORTH OF THE AREA... WITH THE CAD BOUNDARY GENERALLY EXTENDING FROM JUST SOUTH OF KEXX (LEXINGTON) EASTWARD TO THE NORTHERN COASTAL PLAIN. LOW CIGS WITH GENERALLY LIGHT AND VARIABLE RAIN ARE COMMON ON THE NORTHERN SIDE OF THE BOUNDARY... WITH SOUTHERLY WINDS IN THE 10 TO 15 KT RANGE... WITH GUSTS OF UP TO 20-25 KTS POSSIBLE SOUTH OF THE BOUNDARY WITH GENERALLY MVFR CIGS (WITH RAIN STILL). THIS LATEST AREA OF RAIN IS EXPECTED TO MOVE ACROSS MOST OF THE AREA OVER THE NEXT 3-5 HOURS. THIS MAY HELP DELAY THE EROSION OF THE CAD AIRMASS AT KRDU AND KRWI BY A FEW HOURS. THUS... HAVE DELAYED CONDITIONS IMPROVING AND ARRIVE OF THE GUSTY WINDS... AND THUS EXTENDED THE THREAT OF LLWS AS SOUTHWESTERLY WINDS OF 40-45 KTS A COUPLE THOUSAND FEET OFF OF THE SURFACE WILL CONTINUE ACROSS CENTRAL NC THROUGH EARLY AFTERNOON. THUS... BY 16Z OR SO EXPECT WINDS TO INCREASE AT KRDU AND KRWI OUT OF THE SOUTHWEST... WITH GUSTS IN THE 20 TO 25 KT RANGE FOR THE AFTERNOON. FURTHER WEST WE MAY NOT SEE THE STABLE AIRMASS BREAK UNTIL EARLY TO MID AFTERNOON. THUS... HAVE PUSHED BACK THE TIMING A BIT... WITH MVFR CIGS NOT EXPECTED UNTIL AFTERNOON... ALONG WITH THE GUSTY SOUTHWESTERLY WINDS. AT KFAY... EXPECT WE WILL SEE THE WIND GUSTS IN THE 20 TO 25 KT RANGE... WITH EVEN 30 KTS NOT OUT OF THE QUESTION IF CIGS INCREASE ENOUGH BEFORE THE CORE OF THE LOW LEVEL JET SHIFTS TO THE EAST THIS AFTERNOON. OTHERWISE EXPECT ON AN OFF RAIN MOST OF THE DAY (FOR KFAY)... WITH GENERALLY MVFR CIGS... TO AT TIMES IFR. A COLD FRONT WILL MOVE ACROSS THE AREA LATE IN THE DAY AND SCOUR OUR ANY LINGERING LOW LEVEL CLOUD COVER.... ALLOWING A RETURN TO VFR CONDITIONS BY AROUND 03Z OR SO. VFR CONDITIONS ARE THEN EXPECTED TO CONTINUE FOR THE REST OF THE TAF PERIOD. LOOKING AHEAD: VFR CONDITIONS SHOULD PREVAIL THROUGH TUESDAY EVENING BUT THEN A SHORTWAVE SYSTEM COULD BRING SUB VFR CONDITIONS FOR WEDNESDAY AND WEDNESDAY NIGHT. CONDITIONS ARE EXPECTED TO RETURN TO VFR AND HOLD THERE THROUGH THE REST PERIOD. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD/BSD SHORT TERM...WSS LONG TERM...WSS AVIATION...BSD
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
359 AM EST MON FEB 11 2013 .SYNOPSIS... A WARM FRONT WILL LIFT NORTH THROUGH THE AREA THIS MORNING AS A COLD FRONT PUSHES EAST THROUGH THE AREA AND OFFSHORE BY TONIGHT. A LOW PRESSURE AREA WILL MOVE NORTHEAST ALONG THE COAST WEDNESDAY...FOLLOWED BY HIGH PRESSURE FOR THURSDAY AND FRIDAY. ANOTHER COLD FRONT WILL MOVE THROUGH THE AREA FRIDAY NIGHT. && .NEAR TERM /TODAY/... AS OF 350 AM MONDAY...ONLY SOME VERY LIGHT PRECIPITATION IS REACHING THE GROUND OVER THE MHX CWA. THE LATEST RAP MODEL STILL SHOWS PRECIPITATION BECOMING MORE WIDESPREAD AFTER 12Z AND WILL CONTINUE TO RAMP UP POPS THROUGH THE EARLY MORNING HOURS...BECOMING CATEGORICAL AFTER 12Z. WARM FRONT CONTINUE TO MOVE NORTH THROUGH THE CWA WITH MOST TEMPERATURES NOW IN THE LOWER TO MIDDLE 50S WITH 62 DEGREES AT CAPE HATTERAS. WITH A FAIRLY DEEP SOUTHERLY FLOW...EXPECT TEMPERATURES TO RISE INTO THE MIDDLE AND UPPER 60S OVER MOST AREAS WITH A FEW SPOTS OVER THE SOUTHERN COUNTIES PERHAPS TOUCHING 70 DEGREES. THINK MOST OF THE WIDESPREAD PRECIPITATION WILL OCCUR BEFORE 18Z...WITH RAIN BECOMING MORE SCATTERED AFTER 18Z. LATEST NAM12 AND GFS SHOW A RIBBON OF INSTABILITY POSITIONING ITSELF JUST OFFSHORE BY LATER TODAY AND HAVE INCLUDED A SLIGHT CHANCE OF THUNDER FOR THE COASTAL WATERS. && .SHORT TERM /TONIGHT/... AS OF 355 AM MONDAY...PRECIPITATION WILL TAPER FROM NORTH TO SOUTH TONIGHT WITH MINIMAL RAIN CHANCES EXPECTED AFTER MIDNIGHT AS DRIER AIR FILTERS INTO THE REGION FROM THE NORTH. CLOUDINESS WILL LIKEWISE DECREASE AS WE HEAD TOWARD THE MORNING HOURS. MINIMUM TEMPERATURES ACROSS THE AREA WILL RANGE FROM 45 TO 50 DEGREES. && .LONG TERM /TUESDAY THROUGH SUNDAY/... AS OF 340 AM MON...UPPER LEVEL TROUGH OVER THE EASTERN GREAT LAKES WILL CONTINUE TO PUSH NE INTO QUEBEC ON TUES WHILE BROAD AND WEAK UPPER RIDGING ESTABLISHES ITSELF ACROSS FL/GULF OF MEXICO. THESE FEATURES WILL PRODUCE WESTERLY FLOW ALOFT. SURFACE HIGH PRESSURE NORTH OF THE AREA WILL MOVE INTO THE REGION TUES BRINGING WARM TEMPS INTO EASTERN NC...WITH HIGHS IN THE LOW/MID 60S. MONDAY`S COLD FRONT WILL REMAIN STALLED OFF THE SE COAST WITH AN AREA OF LOW PRESSURE FORMING ALONG THE BOUNDARY OVER THE SE STATES TUES NIGHT INTO WED MORNING. GREATER DIFFERENCES EXIST BETWEEN THE 00Z RUNS OF THE GFS AND ECMWF WITH THE SURFACE LOW TRACK FARTHER INLAND WITH THE GFS SCENARIO WHILE THE ECMWF LOW TRACKS ALONG THE COAST...SIMILAR TO PREVIOUS RUNS. THE GFS IS ALSO STRONGER WITH THE MIDLEVEL SHORTWAVE DIGGING SOUTHEAST ACROSS THE SOUTHERN STATES. HEDGED SLIGHTLY CLOSER TO THE GFS GIVEN ITS OPERATIONAL SUPPORT WITH THE GFS ENSEMBLE. THIS WILL MEAN SLIGHTLY MORE QPF BUT A CONTINUATION OF HIGH POPS TO CATEGORICAL BY WED ACROSS SOUTHERN HALF OF THE CWA. EXPECT PRECIP TO END FROM WEST TO EAST LATE WED NIGHT AS THE SURFACE LOW PUSHES NE INTO THE NORTHERN ATLANTIC OCEAN. STRONG SHORTWAVE ALOFT WILL ALSO PUSH THROUGH THE REGION WED NIGHT...WITH RIDGING SURFACE AND ALOFT BUILDING INTO EASTERN NC THURS. THE HIGH WILL PUSH OFFSHORE FRI. TEMPS WILL BE NEAR CLIMO THURS AND FRI. BY EARLY WEEKEND IT APPEARS MORE LIKELY THAT AN ARCTIC AIRMASS WILL INVADE THE EASTERN CONUS AS BOTH GFS/ECMWF INDICATE DEEP TROUGHING ALOFT...AND CONTINUED TO HEDGE CLOSER TO THE ECMWF FOR LATE IN THE EXTENDED. THERE COULD BE SOME SHOWERS SAT AHEAD OF THE ARCTIC COLD FRONT...AND WILL MAINTAIN SLIGHT CHANCE POPS. SUN WILL BE QUITE A BIT COLDER WITH HIGHS IN THE LOW/MID 40S. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... SHORT TERM /THROUGH MONDAY/... AS OF 1245 AM MONDAY...ONLY MADE MINOR TIMING ADJUSTMENTS FOR THE LATEST TAF CYCLE. LOW-LEVEL MOISTURE WILL CONTINUE TO PUSH INTO EASTERN NORTH CAROLINA AS A WARM FRONT LIFTS TO THE NORTH THIS MORNING. PER LATEST 4 KM WRF AND RAP MODELS...LIGHT RAIN SHOULD BECOME WIDESPREAD BY AROUND 12Z. AS A COLD FRONT THEN MOVES ACROSS THE AREA...RAIN WILL PERSIST INTO THE EVENING BEFORE THE FRONT SHIFTS OFFSHORE. A STRONG LLJ WILL DEVELOP...SO EXPECT GUSTY WINDS TO INCREASE MONDAY MORNING THROUGH THE AFTERNOON. CROSSWINDS WILL BE AN ISSUE FOR SITES USING A E-W OR NW-SE ORIENTED RUNWAY. RAINS WILL CONTINUE ALL DAY WITH CEILINGS FLIRTING NEAR OR JUST BELOW IFR. LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... AS OF 340 AM MON...EXPECT PREDOMINANT VFR CONDITIONS TUES AS HIGH PRESSURE BUILDS SOUTH OVER THE TERMINALS. SUB-VFR EXPECTED LATE TUES NIGHT AS AN AREA OF LOW PRESSURE DEVELOPS TO THE SW AND MOVES NE OVER EASTERN NC. ADDITIONAL PRECIP WITH LOWERED CEILINGS AND VSBYS POSSIBLE ON WED. RETURN TO VFR EXPECTED THURS AS HIGH PRESSURE BUILDS ACROSS EASTERN NC. && .MARINE... SHORT TERM /THROUGH MONDAY/... AS OF 355 AM MONDAY...AS WARM FRONT LIFTS NORTH OF THE REGION...GUSTY SOUTH TO SOUTHWEST WINDS WILL DEVELOP THIS MORNING WITH 20 TO 25 KNOT SPEEDS LIKELY BY AROUND MID-MORNING. PER LATEST LOCAL NWPS MODEL...WILL SEE SEAS INCREASE TO AS HIGH AS 11 FEET OVER SOME OF THE CENTRAL AND NORTHERN WATERS TODAY INTO TONIGHT. THE WINDS WILL BECOME MORE W/WNW BEHIND THE FRONT AS IT MOVES OFFSHORE LATER TONIGHT AND SHOULD GRADUALLY SUBSIDE TOWARD MORNING. GIVEN GOOD CONSISTENCY IN MODEL WIND FIELDS...NO CHANGES HAVE BEEN MADE TO CURRENT SMALL CRAFT ADVISORIES. LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 345 AM MON...HIGH PRESSURE BUILDS IN FOR TUES BRINGING GOOD BOATING CONDITIONS. WEAK LOW PRES WILL DEVELOP DURING THE DAY WED SW OF THE NC COASTAL WATERS. THIS WILL BRING EASTERLY WINDS TO START ACROSS THE AREA. CONDITIONS LOOK TO REMAIN SUB SCA HOWEVER ON WED. DURING THE AFTERNOON WED...AS THE LOW PULLS EASTWARD... WINDS WILL SWITCH TO THE WEST AND THEN NORTHWEST BY EVENING. EXPECT A BRIEF PERIOD OF 15-25 KT WINDS AND SEAS 6-8 FT WED NIGHT INTO EARLY THUR. HIGH PRESSURE WILL BE IN CONTROL FOR THE REMAINDER OF THE WEEK BRINGING GOOD BOATING CONDITIONS. LOCAL SWAN/NWPS IN GOOD SHAPE THROUGH THURS THEN BLENDED PREVIOUS SEAS FORECAST WITH LATEST WAVEWATCH III GUIDANCE THURS NIGHT AND FRI WITH NO MAJOR CHANGES. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 10 PM EST THIS EVENING FOR AMZ135. SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST THIS EVENING FOR AMZ130. SMALL CRAFT ADVISORY UNTIL 10 AM EST TUESDAY FOR AMZ152-154. SMALL CRAFT ADVISORY UNTIL 7 AM EST TUESDAY FOR AMZ156-158. SMALL CRAFT ADVISORY UNTIL 4 AM EST TUESDAY FOR AMZ150. && $$ SYNOPSIS...CTC NEAR TERM...CTC SHORT TERM...CTC LONG TERM...DAG AVIATION...CTC/DAG MARINE...CTC/DAG
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1248 AM EST MON FEB 11 2013 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE MOVING OFFSHORE TONIGHT AND A WARM FRONT WILL LIFT NORTH THROUGH THE AREA LATE TONIGHT. A COLD FRONT WILL SLOWLY MOVE THROUGH THE AREA MONDAY AND PUSH OFFSHORE MONDAY NIGHT...STALLING JUST SOUTH OF THE AREA TUESDAY. A LOW PRESSURE AREA WILL MOVE NORTHEAST ALONG THE COAST WEDNESDAY...FOLLOWED BY HIGH PRESSURE FOR THURSDAY AND FRIDAY. A COLD FRONT WILL MOVE THROUGH THE AREA FRIDAY NIGHT. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1240 AM MONDAY...WARM FRONT LIES JUST OFF OUR SOUTHERN COAST AS OF 05Z WITH TEMPERATURES IN THE 60S AT FRYING PAN BUOY AND AT THE BUOY 30 MILES SOUTHEAST OF NEW RIVER. MEANWHILE...TEMPERATURES GENERALLY IN THE MIDDLE 40S TO AROUND 50 OVER LAND AREAS. THE WARM FRONT WILL PIVOT TO THE NORTH OF THE REGION WITH TEMPERATURES SLOWLY RISING THROUGH THE EARLY MORNING HOURS. THE LEADING EDGE OF THE RAIN SHIELD IS JUST NOW REACHING OUR FAR WESTERN COUNTIES. PER LATEST 4 KM WRF AND RAP MODELS...THE PRECIPITATION SHOULD BECOME MORE WIDESPREAD AFTER ABOUT 11Z OR 12Z. CURRENT FORECAST ON TRACK WITH POPS RAMPING UP TOWARD MORNING. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... AS OF 300 PM SUNDAY...PER NEAR TERM...MODELS REMAIN IN DECENT AGREEMENT FOR PERIOD...AND NO SIGNIFICANT CHANGES TO PREVIOUS FCST. STRONG WAA EXPECTED TO PRODUCE WDSPRD PCPN EVENT...BUT ENOUGH MODEL DIFFERENCES ON QPF TO LIMIT CONFIDENCE IN GOING WITH 100% POPS. ALSO WILL NOT INTRODUCE MENTION OF TSTMS AS LACK OF INSTABILITY EXPECTED TO LIMIT CONVECTION. EVEN WITH CLOUDS AND PCPN...STRONG S-SW FLOW WILL ALLOW MAX TEMPS TO REACH INTO MID-UPR 60S. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... AS OF 330 PM SUN...MEDIUM TO LONG TERM PERIOD WILL CONTINUE TO FAVOR MORE CONSISTENT ECMWF. THE PERIOD WILL START OUT DRY WITH HIGH PRESSURE FOR TUESDAY...FOLLOWED BY INCREASING RAIN CHANCES LATE TUE NIGHT AND CONTINUING THROUGH WED...THEN A DRY PERIOD FOR THE END OF THE WEEK. SHARPLY COLDER TEMPS EXPECTED FOR THE SECOND HALF OF THE WEEKEND. FOR MON NIGHT...SOME LINGERING SHOWERS WILL ACCOMPANY COOL FRONT DROPPING SOUTH THROUGH EASTERN NC...ESP FOR THE SOUTHERN HALF OF THE FA. HAVE RAISED POPS A BIT HERE ACCORDINGLY TO FALL MORE IN LINE WITH ECM MOS. VERY DRY HIGH PRES WILL MOVE INTO THE REGION TUE. THE DRYING WILL BE AIDED BY COMPRESSIONAL 850MB WNW FLOW OFF THE SRN APPALACHIANS. THIS WILL ALSO BRING WARM TEMPS INTO E NC...WITH HIGHS IN THE LOW TO MID 60S. THE LIMITING FACTOR FOR SERIOUS FIRE WEATHER CONCERNS WILL BE THE LIGHT SFC WINDS...ONLY ON ORDER OF 5 TO 10 KT. BOUNDARY LAYER WILL BE QUITE DRY TO START TUE NIGHT...THOUGH BY LATE NIGHT THE AREA WILL BE UNDER THE NOSE OF A FAIRLY STRONG SWLY LLJ. ISENTROPIC LIFT WILL INCREASE QUITE DRASTICALLY AFTER AROUND 06Z... AND INHERITED LIKELY POPS STILL LOOK GOOD FOR SOUTHERN TWO THIRDS OF THE FA. WEAK SFC CYCLOGENESIS OCCURS DURING THE DAY WED ACROSS SRN COASTAL WATERS...KEEPING THE FCST AREA IN THE COOL SECTOR. HAVE BROUGHT TEMPS DOWN 5 TO 7 DEGREES FOR HIGHS WED DUE TO LOW LEVEL NNE FLOW AND PLENTIFUL LOW CLOUDS AND LIGHT PRECIP. ECM MOS WAS PREFERRED OVER GFS MOS...AS GFS WAS ON THE WARM SIDE WITH SFC LOW A BIT FURTHER NORTH. LOOKS TO BE A HIGH POP/LOW QPF EVENT WITH WEAK UPR LEVEL SUPPORT...AND MUCH OF THE LIFT WILL BE CONFINED BELOW 700MB. ORGANIZED SHOWERS MOVE EAST WED EVENING WITH DEPARTING SFC LOW... THOUGH COULD SEE SOME REMAINING ISOLATED SHOWERS AS MID LEVEL SHORTWAVE SWINGS THROUGH. HIGH PRES WILL BUILD IN FOR THUR AND FRI BRINGING DRY CONDITIONS AND NEAR NORMAL TEMPS. LOOKING AHEAD TO THE WEEKEND...IT IS LOOKING MORE LIKELY THAT AN ARCTIC AIRMASS WILL INVADE THE EASTERN CONUS AS BOTH GFS/EMWF AND THEIR ENSEMBLE MEAN HEIGHT FIELDS INDICATE DEEP TROUGHING IN THE EAST. SIDED WITH THE ECMWF FOR TIMING...AS GFS IS ABOUT 24 FASTER. THE ECM HAS SUPPORT FROM ITS ENSEMBLE MEAN HEIGHT FIELDS WHICH HAS BETTER CLUSTERING BEYOND THE 156 HOUR TIME FRAME. THERE COULD BE SOME SHOWERS SATURDAY AHEAD OF THE ARCTIC COLD FRONT...THOUGH THIS FAR OUT WILL NOT INTRODUCE HIGHER THAN SLIGHT CHANCE POPS. SUNDAY WILL BE QUITE A BIT COLDER WITH HIGH STRUGGLING INTO THE 40S. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... SHORT TERM /THROUGH MONDAY/... AS OF 1245 AM MONDAY...ONLY MADE MINOR TIMING ADJUSTMENTS FOR THE LATEST TAF CYCLE. LOW-LEVEL MOISTURE WILL CONTINUE TO PUSH INTO EASTERN NORTH CAROLINA AS A WARM FRONT LIFTS TO THE NORTH THIS MORNING. PER LATEST 4 KM WRF AND RAP MODELS...LIGHT RAIN SHOULD BECOME WIDESPREAD BY AROUND 12Z. AS A COLD FRONT THEN MOVES ACROSS THE AREA...RAIN WILL PERSIST INTO THE EVENING BEFORE THE FRONT SHIFTS OFFSHORE. A STRONG LLJ WILL DEVELOP...SO EXPECT GUSTY WINDS TO INCREASE MONDAY MORNING THROUGH THE AFTERNOON. CROSSWINDS WILL BE AN ISSUE FOR SITES USING A E-W OR NW-SE ORIENTED RUNWAY. RAINS WILL CONTINUE ALL DAY WITH CEILINGS FLIRTING NEAR OR JUST BELOW IFR. LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... AS OF 330 PM SUN...COULD BE SOME LINGERING SHOWERS MAINLY AT KEWN AND KOAJ MON NIGHT BEFORE HIGH PRES MOVES IN LATE NIGHT INTO TUESDAY. MORE RAIN MOVES IN LATE TUE NIGHT AND LINGERS THROUGH WED. THERE COULD BE SUB VFR CIGS WITH THE SHOWERS. HIGH PRES BUILDS FOR THUR AND FRI. && .MARINE... SHORT TERM /THROUGH MONDAY/... AS OF 1245 AM MONDAY...LIGHT ESE/SE WINDS WILL BECOME MORE SOUTHERLY AND INCREASE OVER THE NEXT FEW HOURS AS A WARM FRONT LIFTS NORTH OF THE REGION. SMALL CRAFT CONDITIONS SHOULD DEVELOP TOWARD MORNING AS LATEST 10M WIND FORECASTS FOR THE HIGH-RES WRF AND RAP MODELS INDICATE WIDESPREAD 20 TO 25 KNOT WINDS BY 10Z OR SO. SEAS WILL BUILD TO 6 TO 9 FT IN RESPONSE TO THE INCREASED FLOW. SOUTHERLY WINDS AHEAD OF THE APPROACHING COLD FRONT WILL INCREASE WINDS TO 25 TO 30 KNOTS WITH SEAS BUILDING 7-10 FT LATER TODAY. NO CHANGES TO THE CURRENT SCA HEADLINES BEGINNING OVERNIGHT. BLEND OF WW3...NWPS AND PREVIOUS FCST USED FOR SEAS. LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 330 PM SUN...SW WINDS WILL SLOWLY DIMINISH THROUGH MON EVENING THOUGH SEAS WILL REMAIN 6 FEET OR HIGHER THROUGH THE OVERNIGHT. HIGH PRES BUILDS IN FOR TUE BRINGING GOOD BOATING CONDITIONS. WEAK LOW PRES WILL DEVELOP DURING THE DAY WEDNESDAY ACROSS THE SOUTHERN NC COASTAL WATERS. THIS WILL BRING EASTERLY WINDS TO START ACROSS THE AREA. CONDITIONS LOOK TO REMAIN SUB SCA HOWEVER ON WED. DURING THE AFTERNOON AS THE LOW PULLS EASTWARD WINDS WILL SWITCH TO THE WEST AND THEN NORTHWEST BY EVENING. COULD BE A BRIEF PD WHERE WINDS NEAR 25 KT AND WAVES OF 6 FT OR HIGHER WED NIGHT INTO EARLY THUR. HIGH PRESSURE WILL BE IN CONTROL FOR THE REMAINDER OF THE WEEK BRINGING GOOD BOATING CONDITIONS. A STRONG COLD FRONT LOOKS TO MOVE THROUGH THE SECOND HALF OF THE WEEKEND BRINGING THE POTENTIAL FOR SCA WINDS/SEAS ON STRONG NW WINDS. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 10 PM EST THIS EVENING FOR AMZ135. SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST THIS EVENING FOR AMZ130. SMALL CRAFT ADVISORY UNTIL 10 AM EST TUESDAY FOR AMZ152-154. SMALL CRAFT ADVISORY UNTIL 7 AM EST TUESDAY FOR AMZ156-158. SMALL CRAFT ADVISORY FROM 4 AM EARLY THIS MORNING TO 4 AM EST TUESDAY FOR AMZ150. && $$ SYNOPSIS...JBM NEAR TERM...CTC SHORT TERM...JBM LONG TERM...TL AVIATION...RSB/CTC/TL MARINE...RSB/CTC/TL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1240 AM EST MON FEB 11 2013 .SYNOPSIS... A WARM FRONT WILL LIFT NORTH ACROSS THE AREA OVERNIGHT. RAIN IS EXPECTED TONIGHT INTO MONDAY AHEAD OF A PRE-FRONTAL TROUGH. A COLD FRONT WILL MOVE ACROSS THE AREA EARLY ON TUESDAY...BEFORE STALLING. A DEEPENING LOW PRESSURE SYSTEM WILL MOVE ACROSS THE AREA ON WEDNESDAY...WITH HIGH PRESSURE RETURNING FOR THE END OF THE WEEK. AN ARCTIC BLAST MAY REACH THE EASTERN CAROLINAS IN THE WAKE OF A COLD FRONT NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 12:40 AM MONDAY...LIGHT RAIN HAS PROGRESSED EASTWARD ACROSS ALL BUT THE COASTAL COUNTIES. NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. LOOKS LIKE VIRTUALLY ALL AREAS...EXCEPT POSSIBLY FOR SPOTS IN GEORGETOWN COUNTY...WILL SEE RAIN OVERNIGHT. PREVIOUS DISCUSSIONS FOLLOW BELOW: THE FORECAST REMAINS ESSENTIALLY ON-TRACK THIS EVENING. REGIONAL RADAR COMPOSITES SHOW ECHOES NOT QUITE TO I-95...AND SURFACE OBS SHOW PRECIP IS REACHING THE GROUND UNDER ALL BUT THE 15 DBZ AND LOWER RADAR REFLECTIVITIES. THE LATEST SEVERAL RUNS OF THE RUC AND HRRR MODELS SUGGEST A LIGHTER-QPF EVENT THAN WAS INITIALLY THOUGHT...AND WITH A SOUTHWARD SHIFT IN THE LOCATION OF HEAVIEST RAINFALL IN THE 3-6 A.M. TIME FRAME. SINCE THIS IDEA APPEARS TO BE SUPPORTED BY LIGHT RADAR ECHOES OBSERVED AS FAR SOUTH AS AUGUSTA GA...I HAVE INCREASED POPS FOR THE SOUTHERN END OF THE SC PEE DEE REGION AND DOWN TO THE COAST BY 10-20 PERCENT...ALTHOUGH WITH NO ATTENDANT INCREASE IN FORECAST RAINFALL AMOUNTS. THE SYNOPTIC PATTERN HAS A WARM FRONT EXTENDING FROM JUST SOUTH OF CAPE LOOKOUT TO NEAR CAROLINA BEACH...THEN SOUTH-SOUTHWESTWARD JUST OFFSHORE FROM MYRTLE BEACH AND GEORGETOWN. IN RESPONSE TO STRENGTHENING SOUTH FLOW THE FRONT IS LIFTING NORTHWARD AT AN INCREASING RATE AND MAY "JUMP" NORTH THROUGH MY ENTIRE FORECAST AREA IN THE NEXT COUPLE OF HOURS. EASTERLY SURFACE WINDS WILL VEER SOUTHERLY AND INCREASE TO 10-15 MPH...WITH 20-25 MPH GUSTS POSSIBLE AFTER MIDNIGHT. A HEALTHY UPPER TROUGH EXTENDS SOUTHWARD FROM AN UPPER LOW IN SOUTHERN MINNESOTA. PLENTY OF GULF MOISTURE ADVECTED NORTH AHEAD OF THIS TROUGH IS PRODUCING SEVERE WEATHER AND HEAVY RAINFALL ACROSS THE DEEP SOUTH. ALTHOUGH THE AIRMASS OVER THE EASTERN CAROLINAS SHOULD REMAIN TOO STABLE FOR CONVECTION...THIS SAME MOISTURE FEED IS WHAT WILL CREATE OUR RAINFALL CHANCES TONIGHT. BY DAYBREAK RAINFALL AMOUNTS AROUND A HALF INCH ARE EXPECTED ACROSS DARLINGTON COUNTY... TAPERING DOWN TO AROUND A THIRD OF AN INCH FROM LUMBERTON INTO MARION AND FLORENCE. CLOSER TO THE COAST AND SOUTH TOWARD THE SANTEE RIVER RAINFALL AMOUNTS OF ONE OR TWO-TENTHS OF AN INCH ARE EXPECTED BY DAYBREAK. WE ARE AT OUR LOW TEMPERATURES CURRENTLY...AND READINGS SHOULD RISE BY 3-5 DEGREES OVER THE NEXT SEVERAL HOURS AS WARMER AIR FROM GEORGIA AND OFFSHORE SOUTH CAROLINA ADVECTS OVERHEAD. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/... AS OF 3 PM SUNDAY...COMPLICATED AND CHALLENGING FORECAST PERIOD. FORECAST AREA WILL BE IN THE WARM SECTOR AHEAD OF PRE-FRONTAL TROUGH ON MON. EVEN WITH AN ABUNDANCE OF CLOUD COVER...CAPE VALUES MAY STILL REACH UP TO 500 J/KG MON AFTERNOON. DEEP MOISTURE WILL BE IN PLACE...WITH PRECIPITABLE WATER VALUES NEAR 1.5 INCHES. THE HIGHEST INSTABILITY WILL BE ACROSS THE SOUTHERN AND EASTERN ZONES...THUS ADDED ISOLATED THUNDERSTORMS TO THE FORECAST FOR MON AFTERNOON. GIVEN THE MAGNITUDE OF LIFT...HIGHLY CONFIDENT THERE WILL BE SHOWERS AND WILL CARRY CATEGORICAL POPS MON. AS THE PRESSURE GRADIENT TIGHTENS ON MON...SW LOW LEVEL JET WILL INCREASE TO 40 TO 50 KT AND EXPECT SOME WIND GUSTS ON MON TO AROUND 30 MPH. ONCE THE PRE-FRONTAL TROUGH MOVES THROUGH MON AFTERNOON/EARLY EVE...LASTLY ALONG THE COAST...DRIER AIR IN THE LOW AND MID LEVELS WILL WORK INTO THE FORECAST AREA. THIS DRIER AIR SHOULD LARGELY CUT OFF THE RISK FOR PRECIPITATION...BUT GIVEN THE ACTUAL FRONT WILL NOT LIMP INTO THE FORECAST AREA TIL TUE MORNING...WILL CARRY SMALL POPS FOR PORTIONS OF THE AREA EVEN AFTER DARK MON. ATTENTION THEN TURNS TO A SOUTHERN STREAM SYSTEM WHICH WILL BE DEVELOPING ALONG THE GULF COAST IN RESPONSE TO A HIGHLY ENERGIZED MID-LEVEL SHORTWAVE MOVING ACROSS THE SOUTHERN PLAINS TUE. THE EUROPEAN MODEL HAS BEEN THE MOST CONSISTENT AND CONTINUES TO INDICATE SURFACE LOW PRESSURE MOVING ALONG A STALLED FRONT AND REACHING THE SE STATES TUE NIGHT...BEFORE TRANSFERRING TO THE CAROLINA COAST DURING WED. STILL SOME DISCREPANCY AS TO HOW FAR N THE STRONGEST ISENTROPIC UPGLIDE WILL DEVELOP AND THUS WHERE THE HEAVIEST RAIN WILL DEVELOP. CONFIDENT THAT POPS...WHICH HAD BEEN TRENDED LOWER MON NIGHT INTO TUE...WILL BEGIN TO REVERSE HIGHER... FROM S TO N...TUE AFTERNOON AND ESPECIALLY TUE NIGHT. WILL BRING POPS BACK TO CATEGORICAL OVERNIGHT TUE INTO WED MORNING. THE CHARACTER OF PRECIPITATION THIS TIME AROUND SHOULD BE STRATIFORM AS LONG AS THE MORE SOUTHERN TRACK VERIFIES AND WILL NOT ADD THUNDERSTORMS TO THE TUE FORECAST AT THIS TIME. CONFIDENCE IN THE QPF FORECAST HAS NOT INCREASED...BUT AT THIS TIME WE ARE FORECASTING A 1 TO POSSIBLY 3 INCH RAINFALL EVENT THROUGH MID WEEK. THIS AMOUNT OF RAIN SHOULD NOT BE ENOUGH TO CAUSE FLOODING ALTHOUGH RIVERS WILL LIKELY BE ON THE RISE MID AND LATE WEEK. SHOULD SIGNIFICANTLY HIGHER RAINFALL AMOUNTS MATERIALIZE...THE RISK FOR SOME FLOODING WOULD INCREASE. LATER FORECASTS WILL STRIVE TO BETTER DEFINE THE TOTAL AMOUNT OF RAINFALL AND ANY FLOOD RISK. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 3 PM SUNDAY...MAIN FOCUS WILL BE ON THE EARLY PART OF THE FORECAST WHERE POPS REMAIN A DILEMMA AND THE END OF THE PERIOD WHERE ARCTIC AIR WILL BE AN ISSUE. FOR WEDNESDAY...THERE REMAINS A DIFFERENCE IN MEDIUM RANGE GUIDANCE AS THE ECMWF IS LESS AMPLIFIED AND HENCE MORE PROGRESSIVE WITH THE MAIN UPPER LEVEL FEATURE MOVING ACROSS THE TENNESSEE VALLEY. THE GFS REMAINS CONSISTENT WITH A SLOWER AND DEEPER SOLUTION. I HAVE MAINTAINED THE INHERITED CATEGORICAL POPS BASED PRIMARILY ON CONTINUITY OF THE GFS ALTHOUGH IT SHOULD BE NOTED CONFIDENCE EVEN JUST A FEW DAYS OUT REMAINS UNUSUALLY LOW. FOR THURSDAY THROUGH SATURDAY...A BROAD EASTERN U.S. TROUGH DEVELOPS WITH SURFACE HIGH PRESSURE CENTERED ACROSS THE SOUTHERN U.S. EXPECT TEMPERATURES AT OR JUST BELOW CLIMATOLOGY ALONG WITH DRY CONDITIONS. AS THE EASTERN PACIFIC RIDGE DEVELOPS THROUGH THE PERIOD... SEVERAL SHORTWAVES WILL DIVE SOUTH AND REINFORCE THE BROAD TROUGH THUS RELEASING A SHOT OF ARCTIC AIR. THE 0600 OPERATIONAL GFS WAS ADVERTISING 850MB TEMPERATURES AS COLD AS MINUS 15 DEGREES C MOVING ACROSS THE AREA BRIEFLY NEXT SUNDAY. HOWEVER THE 1200 UTC GUIDANCE HAS MODERATED SOMEWHAT AND THESE NUMBERS APPEAR MORE REASONABLE. ACTUAL LOWS WILL BE MODULATED BY DECOUPLING OR LACK THEREOF. IT HAS ALSO BEEN MY EXPERIENCE IN THE PAST THAT ARCTIC AIR OUTBREAKS LATER IN THE SEASON WITH THE HIGHER SUN ANGLES MAKE MEX NUMBERS MORE ACCURATE. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 06Z...CURRENTLY VFR AT ALL TERMINALS. A LARGE AREA OF RAIN IS MOVING ACROSS THE KFLO/KLBT TERMINALS TOWARDS THE COASTAL TERMINALS. CONFIDENCE IS HIGH THAT FLIGHT CONDITIONS WILL DETERIORATE TO MVFR DUE TO MAINLY REDUCED VSBYS IN RAIN AND BR AT KFLO/KLBT EARLY THIS MORNING. THE HEAVIEST OF THE RAIN SHOULD OCCUR 08Z-14Z AND IT IS DURING THIS TIME THAT THE GREATEST THREAT OF IFR WILL OCCUR. MOST OF THE RAIN SHOULD END BY 14Z BUT THERE WILL REMAIN A GOOD CHANCE OF MVFR CONDITIONS/SHOWERS THROUGH 19Z AND MVFR CIGS THROUGH 22Z. THERE IS HIGH CONFIDENCE OF MVFR CONDITIONS DEVELOPING AT THE COASTAL TERMINALS BY 08-09Z. THE HEAVIEST OF RAIN SHOULD OCCUR IN THE 12Z-17Z TIME FRAME. IT IS DURING THIS TIME THE GREATEST THREAT OF IFR WILL OCCUR. THERE MAY BE A TEMPO LULL IN PRECIPITATION INTENSITY BY 16-17Z...BUT THERE WILL REMAIN A GOOD CHANCE OF TEMPO IFR/SHOWERS THROUGH 20-21Z...AND MVFR CIGS THROUGH THE EVENING. EXTENDED OUTLOOK...RAIN LIKELY WITH PERIODS OF MVFR/IFR CONDITIONS THROUGH WEDNESDAY. VFR DEVELOPING THURSDAY AND PERSISTING THROUGH FRIDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 12:40 AM MONDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. SMALL CRAFT ADVISORY REMAINS IN EFFECT. LATEST OBS SHOW 3 TO 5 FT SEAS BUT WINDS ARE STILL ON THE INCREASE. PREVIOUS DISCUSSION FOLLOWS BELOW: THE WARM FRONT IS FINALLY BEGINNING TO MAKE A MOVE TO THE NORTH...CURRENTLY EXTENDING FROM JUST SOUTH OF CAPE LOOKOUT TO NEAR CAROLINA BEACH...THEN SOUTH-SOUTHWESTWARD THROUGH THE SOUTH CAROLINA COASTAL WATERS REMAINING JUST EAST OF GEORGETOWN. ON THE COOL SIDE OF THIS BOUNDARY SURFACE WINDS REMAIN EASTERLY. THE SOUTHERLY WINDS OVER THE FRONT ARE ERODING THE COOLER SURFACE AIR RATHER QUICKLY...AND THE FRONT SHOULD "JUMP" NORTH ACROSS MY FORECAST AREA IN THE NEXT SEVERAL HOURS...WITH SOUTHERLY WINDS AT THE SURFACE THE ANTICIPATED RESULT. WIND SPEEDS SHOULD INCREASE TO 20-25 KT...BUT WITHOUT ANY SUBSTANTIAL GUSTINESS GIVEN VERY STABLE THERMODYNAMIC PROFILES. SEAS CURRENTLY 3-4 FT WILL BEGIN TO BUILD SUBSTANTIALLY AFTER MIDNIGHT AND COULD REACH 8 FEET ACROSS THE OUTER PORTION OF THE COASTAL WATERS BY DAYBREAK MONDAY. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 PM SUNDAY...A MOIST AND INCREASING SOUTHERLY FLOW WILL DEVELOP AHEAD OF A PRE-FRONTAL TROUGH. SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED TO HAVE ALREADY BEGUN BY THE START OF THE PERIOD AND TO CONTINUE INTO MON NIGHT...SSW TO SW WINDS TO 20 TO 25 KT WITH SEAS PEAKING IN THE 6 TO 10 FT RANGE...HIGHEST ACROSS THE OUTER NORTHERN WATERS. DECREASING WINDS WILL VEER TO W BEHIND THE PRE-FRONTAL TROUGH MON EVE AND THEN BECOME NW BEHIND A COLD FRONT TUE MORNING. WINDS AND SEAS ARE EXPECTED TO FALL BELOW ADVISORY CRITERIA LATE MON NIGHT. SINCE DEWPOINTS WILL BE CLIMBING INTO THE LOWER 60S...THERE IS SOME RISK FOR THE DEVELOPMENT OF SEA FOG ON MON. AT THIS TIME...GIVEN THE MAGNITUDE OF WIND...WILL OPT FOR STRATUS OVER FOG AND WILL LEAVE OUT OF THE FORECAST. AS LOW PRESSURE APPROACHES FROM THE W AND SW TUE NIGHT...WINDS WILL SHIFT TO THE NE AND THEN ENE...INCREASING WITH THE APPROACH OF DAYBREAK WED. LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 3 PM SUNDAY...CHANGEABLE CONDITIONS AT LEAST THROUGH THE EARLY PART OF THE PERIOD...WILL BE THE HIGHLIGHT OF THE FORECAST. EASTERLY FLOW INITIALLY WILL QUICKLY GIVE WAY TO A SOUTHERLY FLOW BY MIDDAY WEDNESDAY AS A WARM FRONT MOVES ACROSS TO THE NORTH. WINDS THEN QUICKLY VEER TO WEST NORTHWEST BY EARLY THURSDAY AS A COLD FRONT MOVES ACROSS. BY FRIDAY WINDS ESSENTIALLY BECOME LIGHT AND VARIABLE AS HIGH PRESSURE DRIFTS OVERHEAD. FOR SEAS...SOME RESIDUAL SIX FOOTERS MAY WARRANT AN ADVISORY FOR PART OR MOST OF WEDNESDAY ESPECIALLY ACROSS THE OUTER WATERS BUT LATER THURSDAY AND FRIDAY OFFER MORE BENIGN VALUES WITH THE DIMINISHING OFFSHORE FLOW. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST TUESDAY FOR AMZ250-252-254- 256. && $$ NEAR TERM...REK/JDW SHORT TERM...RJD LONG TERM...SHK AVIATION...MRR MARINE...REK/RJD/JDW/SHK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1214 AM CST MON FEB 11 2013 .DISCUSSION...LATEST WATER VAPOR IMAGERY SHOWS THE UPPER LOW CIRCULATION ALONG THE CENTRAL MINNESOTA/WISCONSIN BORDER WITH A TROWAL EXTENDING INTO FAR EASTERN NORTH DAKOTA. THIS WOULD RESULT IN THE SNOW TO CONTINUE TAPERING OFF IN THE JAMES RIVER VALLEY THROUGH 12Z. COLLABORATED WITH NEIGHBORING OFFICES AND WILL CONTINUE WITH THE CURRENT HEADLINES. VISIBILITIES AROUND ONE MILE IN THE BLIZZARD WARNING BUT IN BETWEEN REPORTING STATIONS AND IN THE OPEN COUNTRY VISIBILITIES COULD POSSIBLY BE LOWER AS WINDS CONTINUE TO GUST NEAR 40 MPH. THE FOG/STRATUS LOOP SHOWS PLENTY OF CLOUD COVER EXTENDING INTO CENTRAL MONTANA AND INTO SASKATCHEWAN AND MANITOBA. LATEST RAP AND NAM 925MB RH FIELD KEEPS THE STRATUS THROUGH 18Z BEFORE ERODING IT ALONG THE EDGES LATER MONDAY AFTERNOON. && .AVIATION...IFR/MVFR CONDITIONS WILL PERSIST AT ALL AERODROMES THROUGH AT LEAST 18Z MONDAY...WITH IMPROVEMENTS TO VFR AT KISN AND KDIK BETWEEN 18Z AND 21Z MONDAY. BLOWING SNOW WILL CONTINUE AT KJMS THROUGH 15Z MONDAY RESULTING IN IFR TO LIFR VSBYS. && .BIS WATCHES/WARNINGS/ADVISORIES... BLIZZARD WARNING UNTIL 6 AM CST MONDAY FOR NDZ037-047-048-050- 051. WINTER WEATHER ADVISORY UNTIL 6 AM CST MONDAY FOR NDZ025-036-046. && $$ DISUCSSION...KS AVIATION...RK/KS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1238 AM EST MON FEB 11 2013 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL MOVE THROUGH THE AREA TONIGHT. HIGH PRESSURE WILL BUILD INTO THE AREA ON MONDAY AND REMAIN ACROSS THE REGION FOR TUESDAY. A STORM SYSTEM WILL MOVE SOUTH OF THE AREA ON WEDNESDAY BRINGING A CHANCE FOR PRECIPITATION TO SOUTHERN PORTIONS OF THE REGION. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... MAIN AREA OF PCPN IS EXITING OUR EASTERN AREAS SO WILL TRIM BACK POPS ACROSS THE EAST IN THE SHORT TERM. PCPN IS TRYING TO FILL IN ACROSS INDIANA AS SUGGESTED BY THE NAM AND HRRR BUT SO FAR IT STILL APPEARS TO BE PRETTY LIGHT. WILL ALLOW FOR CHANCE POPS ASSOCIATED WITH THIS TO SPREAD BACK EAST ACROSS OUR AREA THROUGH THE LATE EVENING AND ON INTO THE EARLY MORNING HOURS BUT EXPECT ANY MEASURABLE PCPN TO BE ON THE LIGHT SIDE. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/... HIGH PRESSURE WILL BEGIN TO WORK INTO THE FA ON MONDAY. THERE WILL BE A BREAK IN THE CLOUDS DURING THE MORNING HOURS ACROSS THE FA. IT IS DURING THIS TIME THAT WINDS WILL INCREASE ACROSS THE FA AND EXPECT THE HIGHEST WINDS ACROSS THE FA DURING THE LATE MORNING TO EARLY AFTERNOON TIME FRAME. SUSTAINED WINDS WILL BE AROUND 20 TO 25 MILES PER HOUR WITH WIND GUSTS AROUND 35 TO 45 MILES PER HOUR. THESE WINDS FALL SLIGHTLY BELOW WIND ADVISORY CRITERIA AND THEREFORE DECIDED NOT TO ISSUE A WIND ADVISORY FOR MONDAY. WILL CONTINUE TO HIGHLIGHT THE WINDS IN THE HWO. ADDITIONAL CLOUDS WILL WORK INTO THE AREA FOR THE AFTERNOON HOURS. GUSTY WINDS WILL REMAIN ACROSS THE FA THROUGH THE AFTERNOON AND EVENING HOURS. WINDS WILL DECREASE ACROSS THE AREA MONDAY NIGHT. TEMPERATURES ON MONDAY WILL NOT RISE MUCH FROM SUNDAY NIGHT LOWS. EXPECT HIGH TEMPERATURES ON MONDAY TO BE IN THE LOW TO UPPER 40S. WITH CLOUD COVER DECREASING ACROSS THE FA MONDAY NIGHT TEMPERATURES WILL DROP DOWN INTO THE 20S ACROSS MOST LOCATIONS. HIGH PRESSURE WILL KEEP DRY CONDITIONS ACROSS THE FA TUESDAY AND INTO TUESDAY NIGHT. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... LOW PRESSURE WILL PASS SOUTH OF THE REGION ON WEDNESDAY. STILL SOME MODEL DISAGREEMENT ON HOW FAR NORTH THE PRECIPITATION SHIELD WILL SPREAD. HAVE LIMITED POPS TO THE FAR SOUTH/SOUTHEASTERN COUNTIES. LOOKS LIKE THIS WOULD BE A MIX OF LIGHT SNOW AND RAIN. ONCE THIS SYSTEM MOVES OFF THERE WILL BE A BRIEF PERIOD OF RIDGING ON THURSDAY. BUT THEN LOW PRESSURE WILL TRACK ACROSS THE GREAT LAKES ON FRIDAY WHICH WILL SWING A COLD FRONT THROUGH THE REGION. COLD NORTHWEST FLOW WILL THEN PREVAIL THROUGH THE WEEKEND. COULD SEE SOME SNOW SHOWERS OR FLURRIES WITH THE FRONT AND INTO THE WEEKEND. BUT NARROWING DOWN A MORE FAVORABLE PERIOD FOR MEASURABLE PRECIPITATION IS PROBLEMATIC THIS FAR OUT IN TIME. SO KEPT POPS MAINLY IN SLIGHT CHANCE CATEGORY. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... MVFR CEILINGS LINGER IN A MOIST SOUTHERLY FLOW ALONG AND AHEAD OF A COLD FRONT. SHOWERS HAVE JUST ABOUT ENDED THOUGH SOME LIGHT RAIN MAY PERSIST AT CMH AND LCK. CONDITIONS WILL IMPROVE TO VFR BY MID MORNING AS THE FRONT PROGRESSES EAST AND DRIER AIR WORKS IN. WINDS WILL BE A PROBLEM WITH GUSTS OVER 30 KNOTS OUT OF THE SOUTHWEST EXPECTED IN A TIGHT PRESSURE GRADIENT BEHIND THE FRONT. WINDS WILL SUBSIDE TO AROUND 12 KNOTS ABOUT 00Z AS DIRECTION SHIFTS TO WEST. OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...NOVAK NEAR TERM...JGL SHORT TERM...NOVAK LONG TERM... AVIATION...CONIGLIO
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1147 PM EST SUN FEB 10 2013 .SYNOPSIS... LOW PRESSURE TRACKING OUT OF THE PLAINS WILL MOVE THROUGH THE UPPER GREAT LAKES ON MONDAY...PULLING AWAY TO THE NORTHEAST ON TUESDAY. A RIDGE WILL EXPAND NORTH ACROSS THE OHIO VALLEY ON TUESDAY AND LINGER INTO WEDNESDAY. A CLIPPER WILL APPROACH THE REGION FROM THE NORTHWEST ON THURSDAY. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... THE FRONT WILL MOVE ACROSS THE AREA LATE TONIGHT AND MONDAY MORNING. THE FIRST BATCH OF SHOWERS HAVE DECREASED...SOME SPRINKLES COULD BE OCCURRING OVER NW PA THROUGH MIDNIGHT. THE DEW POINTS ARE LOW OVER NW PA BUT THE TEMPERATURES ARE WARM ENOUGH AND WILL CONTINUE TO RISE AS WILL THE DEW POINTS. THE THREAT OF THE TEMPERATURE DROPPING TO 32F IS NEGLIGIBLE. ALSO THE ROAD TEMPERATURES ARE NEAR 40F...SO THAT WILL ALSO HELP PREVENT ANY ICY ROADS. THE NEXT BATCH OF SHOWERS WERE TRYING TO DEVELOP OVER WESTERN OHIO. THE HRRR MODEL IS HINTING AT IT...MORE OF A SCATTERED NATURE. THE 12Z 4KM WRF NMM MODEL IS HINTING AT WIDESPREAD SHOWERS DEVELOPING AFTER MIDNIGHT. THAT IS POSSIBLE WITH ENOUGH MOISTURE...PLENTY OF OMEGA AND SOME LOW LEVEL AND UPPER JET HELP...LEFT FRONT QUAD OF THE JET. KEPT THE POPS LIKELY FOR THE OVERNIGHT. CONFIDENCE IS LOW TO MODERATE. RAINFALL AMOUNTS WILL BE UNDER TWO TENTHS OF AN INCH. ADJUSTED SOME OF THE LOWS BASED ON A SLOWER TIMING OF THE FRONT. ALSO REMOVED THE MENTION OF THUNDER AS THE AIRMASS IS TOO STABLE. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/... BY MONDAY MORNING THE MID-LEVEL DRY SLOT WILL HAVE SPREAD EAST ACROSS OUR ENTIRE FORECAST AREA WITH DRY CONDITIONS IN MOST AREAS. HAVE LOWERED POPS IN THE EAST TO JUST A LOW CHANCE AFTER 12Z. THE COLD FRONT WILL MOVE INTO NW OHIO TOWARDS 14Z...CLEARING NW PA DURING THE EARLY AFTERNOON. LOW LEVEL WRAP AROUND MOISTURE WILL INCREASE WITH THE FRONT WITH FAIRLY STEEP LOW LEVEL LAPSE RATES AND ONLY A SLIGHT CHANCE OF RAIN...EVENTUALLY COOLING ENOUGH FOR FLURRIES OR A STRAY SNOW SHOWER LATE. HAVE ISSUED A WIND ADVISORY FOR THE WESTERN HALF OF THE AREA AND LAKESHORE COUNTIES WITH BOTH THE NAM/GFS ADVERTISING A MIXED LAYER TO NEARLY 850MB WHERE WINDS INCREASE TO 50 KNOTS. WITH LITTLE IN THE WAY OF DOWNWARD MOMENTUM WILL HAVE TO RELY ON THE TIGHT PRESSURE GRADIENT AND MECHANICAL MIXING TO SEE THE STRONGER WINDS MATERIALIZE AT THE SURFACE. STILL EXPECTING TO SEE SOUTHWEST WINDS OF 20-30 MPH WITH GUSTS NEAR 50 MPH. TEMPERATURES BEHIND THE LAKE WILL BE MARGINAL FOR LAKE EFFECT BUT ENOUGH CONVERGENCE ALONG THE SHORELINE SHOULD BE ENOUGH FOR LINGERING SNOW SHOWERS EXTREME NE OHIO/NW PA. NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION. A RIDGE WILL EXPAND NORTH OVER THE AREA THROUGH TUESDAY WITH SNOW SHOWERS ENDING BY TUESDAY NIGHT. A SHORTWAVE DROPS THROUGH THE NORTHWEST FLOW ON TUESDAY AND HELPS TO RE-ENFORCE THE TROUGH OVER THE GREAT LAKES. THIS SHOULD HELP TO KEEP LOW PRESSURE SYSTEM EAST OF THE APPALACHIANS ON WEDNESDAY. && .LONG TERM /THURSDAY THROUGH SUNDAY/... THE MODELS HAVE BEEN PRETTY CONSISTENT DEEPENING THE TROUGH ALOFT LATE IN THE WEEK. THE FIRST IN A SERIES OF COLD FRONTS SEEMS TO CROSS THE AREA LATE THURSDAY. NOT MUCH MOISTURE AVAILABLE AND THE FRONT IS WEAK AND WILL HAVE JUST A SLIGHT CHANCE OF SHOWERS THURSDAY AFTERNOON...WITH A CHANCE OF SOME SNOW SHOWERS DEVELOPING THURSDAY NIGHT. APPEARS AS THOUGH A REINFORCING PUNCH OF COLDER AIR WILL ARRIVE FRIDAY AND WILL HAVE A CHANCE OF SNOW SHOWERS FOR THE ENTIRE FORECAST AREA ALTHOUGH AS WE GET CLOSER WE WILL PROBABLY NEED "LIKELY" POPS...PROBABLY AT LEAST FOR NE OH/NW PA. A LITTLE NERVOUS WITH SUCH A DEEP TROUGH PROGGED BY THE WEEKEND THAT SOME CYCLOGENESIS COULD OCCUR BUT PERHAPS IT IS ALL TO THE EAST NEAR THE COAST? IN ANY CASE...WE WILL CONTINUE TO SEE SNOW FLURRIES AND LAKE EFFECT SNOW SHOWERS THIS WEEKEND. NUDGED TEMPERATURES DOWN A COUPLE OF CATEGORIES BY THE WEEKEND WITH HIGHS IN THE 20S AND LOWS MOSTLY IN THE TEENS. WE CAN REFINE THE FORECAST AS WE GET CLOSER. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... ACTIVE CONVECTION ACROSS THE SOUTH CUT OFF THE MOISTURE SOURCE INTO OUR REGION AND HENCE CUT WAY BACK ON THE PRECIPITATION AMOUNTS. VIRTUALLY REMOVED THREAT FOR PRECIPITATION AT ALL AREAS EXCEPT FOR ERIE. CEILINGS AND VISIBILITIES WILL DROP INTO MVFR CATEGORY OVERNIGHT WITH SOME IMPROVEMENT DURING THE DAY ON MONDAY. WINDS ARE GOING TO BE THE PROBLEM OVERNIGHT INTO TOMORROW AS THEY BECOME QUITE GUSTY FROM THE SOUTH TO SOUTHWEST. OTHER PROBLEM WILL BE WIND SHEAR POTENTIAL AT ALL SITES EXCEPT ERIE. EXPECTING SURFACE WINDS TO BE RELATIVELY LIGHT BUT THEN INCREASE IN SPEED DRAMATICALLY TO AROUND 50 KNOTS JUST ABOVE THE SURFACE. THEREFORE...WILL KEEP MENTION OF WIND SHEAR OVERNIGHT. SURFACE TROUGH MOVES THROUGH THE REGION TOMORROW AND WILL LIKELY CAUSE CEILINGS AND POSSIBLY VISIBILITIES TO LOWER ONCE AGAIN. THERE IS THE POSSIBILITY FOR SOME SNOW AGAIN TOMORROW AFTERNOON WITH THE TROUGH AT ERIE. OUTLOOK...NON-VFR MONDAY NIGHT AND CONTINUING INTO TUESDAY. && .MARINE... STRONG LOW PRESSURE WILL TRACK ACROSS THE NORTHERN GREAT LAKES LATER TONIGHT AND MIDDAY. THE ASSOCIATED COLD FRONT WILL SWING ACROSS LAKE ERIE MONDAY MORNING. AS THE COLD ADVECTION DEVELOPS THE HIGHER WINDS WILL MIX DOWN TO THE SURFACE AND GALE FORCE WINDS ARE LIKELY MONDAY AFTERNOON INTO MONDAY NIGHT. THE ICE ON THE LAKE WILL LIKELY SHIFT MONDAY INTO TUESDAY. THE LOW WILL PULL OUT QUICKLY ON TUESDAY AND HIGH PRESSURE WILL BUILD IN FROM THE WEST AND THE MIDDLE OF THE WEEK SHOULD BE RELATIVELY QUIET ON THE LAKE. A SERIES OF COLD FRONTS AND CLIPPER LOW PRESSURE SYSTEMS ARE EXPECTED LATE IN THE WEEK. THE SOUTHWEST FLOW WILL SHIFT TO NORTHWEST AND WINDS WILL INCREASE LATE IN THE WEEK... PROBABLY IN THE 15 TO 30 KNOT RANGE. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...WIND ADVISORY FROM 11 AM MONDAY TO 1 AM EST TUESDAY FOR OHZ011- 012-089. WIND ADVISORY FROM 9 AM TO 7 PM EST MONDAY FOR OHZ003-006>010- 017>020-027>030-036-037. PA...WIND ADVISORY FROM 11 AM MONDAY TO 1 AM EST TUESDAY FOR PAZ001. MARINE...GALE WARNING FROM NOON MONDAY TO 4 AM EST TUESDAY FOR LEZ061- 142>149-162>169. && $$ SYNOPSIS...KEC NEAR TERM...KIELTYKA SHORT TERM...KEC LONG TERM...KOSARIK AVIATION...LOMBARDY MARINE...KOSARIK
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
457 PM EST MON FEB 11 2013 .SYNOPSIS... A COLD FRONT WILL MOVE THROUGH THE AREA EARLY THIS EVENING...FOLLOWED BY WINDY AND COOLER CONDITIONS TONIGHT INTO TUESDAY. LOW PRESSURE OVER THE GULF COAST IS EXPECTED TO TRACK NORTHEAST AND OFF THE DELMARVA PENINSULA LATE WEDNESDAY NIGHT. THIS STORM SYSTEM COULD BRING A PERIOD OF SNOW TO SOUTHEASTERN AREAS LATE WEDNESDAY AND WEDNESDAY NIGHT. MAINLY DRY CONDITIONS WITH A BRISK WESTERLY WIND...AND NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES WILL FOLLOW FOR THURSDAY AND FRIDAY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... EARLY EVENING VIS IMAGERY SHOWING LOW CLOUDS REMAIN EAST OF THE SUSQ VALLEY. LATEST RAP MDL DATA SUGGESTS LITTLE MOVEMENT TO WARM FRONT BEFORE ARRIVAL OF COLD/OCCLUDED FRONT THIS EVENING. THE OVERNIGHT WILL FEATURE A PRETTY TYPICAL POST COLD FRONTAL FLOW PATTERN WITH NORTHWEST FLOW...STRATOCU CEILINGS AND SCATTERED SNOW SHOWERS OVER THE NORTHWEST AND WEST. EXPECT AN INCH OR TWO OF NEW SNOW OVER THE USUAL AREAS DOWNWIND FROM THE LAKE AND OVER UPSLOPE LOCATIONS IN THE LAURELS...BUT LITTLE MORE THAN FLURRIES ELSEWHERE. THE MAIN THING WILL BE THE INCREASE IN WIND AS THE COLDER AIR FILTERS IN. THE BEST PRESSURE RISES MOVE NORTH OF THE STATE...BUT COLD ADVECTION AND SUBSIDENCE MAY BE ENOUGH TO BRING ABOUT SOME ISOLATED WIND GUSTS IN THE ADVISORY RANGE LATER TONIGHT INTO TUESDAY MORNING. WILL KEEP THE CURRENT ADVISORY WIND ADVISORY CONFIGURATION. OVERNIGHT LOWS WILL AVERAGE WELL ABOVE SEASONAL NORMALS IN THE 20S TO LOWER 30S. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... WINDS WILL GRADUALLY DECREASE THROUGHOUT THE DAY TUESDAY WITH MOSTLY CLOUDY TO CLOUDY SKIES ACROSS THE CENTRAL AND NRN ZONES...AND SOME BREAKS OF SUNSHINE OVER THE SOUTHERN TIER OF THE STATE . SCATTERED MORNING SNOW SHOWERS ACROSS THE NW MTNS WILL DIMINISH TO JUST SOME AFTERNOON FLURRIES...AS THE SURFACE HIGH BUILDS ACROSS JUST TO OUR SOUTH BRINGING A LOWER INVERSION HEIGHT AND ALLOWING CLOUDS TO BECOME SHALLOWER IN THE AFTERNOON. HIGHS TUESDAY IN THE 30S AND 40S WILL RANGE FROM NEAR NORMAL OVER THE NORTH TO A BIT ABOVE NORMAL IN THE SOUTH. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... 1016-1018 MB SFC HIGH PRESSURE BUILD NEWD ACROSS THE STATE TUESDAY NIGHT WITH FAIR SKIES...LIGHT WIND...AND CHILLY TEMPS MAINLY IN THE 20S. A FAIRLY AMPLIFIED...SPLIT-FLOW UPPER PATTERN IS FORECAST TO PERSIST THROUGH THE LONG TERM PERIOD ACROSS MUCH OF NORTH AMERICA. SIGNIFICANT PHASING OF THESE BRANCHES FOR A BRIEF TIME OVER THE UPCOMING WEEKEND...WILL USHER IN A BLAST OF VERY COLD AIR WITH TRAJECTORIES RIGHT FROM THE ARCTIC CIRCLE. THE PRIMARY FEATURE OF CONCERN TO BEGIN THIS PERIOD WILL BE LINKED TO THE NOSE OF A QUITE POWERFUL UPPER JET /IN EXCESS OF 140 KTS/ LIFTING NE UP THE APPALACHIAN MTN CHAIN WEDNESDAY. THE INCREASINGLY DIFFLUENT UPPER PATTERN ACROSS THE MID ATLANTIC REGION LATER WED AND WED NIGHT...WILL COMBINE WITH A SLIGHTLY ANOMALOUS SERLY LLVL FLOW AND APPROX 1000 MB SFC LOW PRESSURE CONSOLIDATING/TRACKING RIGHT ACROSS THE DELMARVA REGION AROUND 06Z THURSDAY. SREF AND GEFS PLUMES /OVER THE PAST FEW DAYS/ HAVE GRADUALLY TRENDED TOWARD HIGHER QPF AMTS IN THE FORM OF MAINLY SNOW. EC...CANADIAN AND UKMET ALSO HAVE DISPLAYED A GRADUAL NWD SHIFT TO THE TRACK OF THEIR SFC LOW. USING A BLEND OF ALL THE OPERATIONAL GUIDANCE AND ENSEMBLE MEANS AT HAND PRESENTS US WITH A FAIRLY GOOD CHANCE OF A LIGHT TO MODERATE SNOW EVENT BEGINNING LATE WEDNESDAY AFTERNOON ACROSS THE SWRN HALF OF THE CWA /POSSIBLY MIXED WITH SOME RAIN/...THEN SPREADING NORTH AND EAST AT NIGHT. NUMEROUS SREF AND GEFS PLUMES INDICATE SIGNIFICANT QPF /AOA 0.50 OF AN INCH/ IN THE FORM OF SNOW. SREF/S MEAN 12 HOUR QPF IS AROUND 0.50 ACROSS THE EXTREME SE PART OF THE CWA...WITH THE 0.25 INCH LIQUID EQUIVALENT LINE EXTENDING ALONG MUCH OF INTERSTATE 80 IN CENTRAL PA...THEN ACROSS THE NRN POCONOS. THE 06Z NAM CONTINUES TO TREND TWD HIGHER QPF AS THE MOST AGGRESSIVE MODEL SOLUTION ATTM...AND COMPARABLE WITH SEVERAL OF THE 03Z SREF/ 00Z GEFS PLUMES. THE NAM/S 24-HOUR QPF /FROM ITS APPARENT MILLER B TYPE STORM/ IS AROUND 0.25 INCH ACROSS THE NRN TIER OF PENN...ABOUT 0.50 NEAR I-80...AND OVER 0.75 OF AN INCH ACROSS PORTIONS OF THE LOWER SUSQ REGION. THIS MAGNITUDE OF AN EVENT WOULD BE SOLIDLY IN THE ADVISORY RANGE...WITH POSSIBLY BORDERLINE WINTER STORM WARNING AMOUNTS ACROSS THE SRN HALF OF THE CWA. AT THIS POINT...CONSIDERING MUCH UNCERTAINTY WITH RESPECT TO THE EXACT SECONDARY LOW DEVELOPMENT NEAR THE VA COAST...AND INTERACTION OF THE NRN AND SRN STREAM WAVES...ITS PRUDENT TO RAMP UP THE SNOW PROBABILITIES AND AMOUNTS GRADUALLY...AND HEIGHTEN AWARENESS IN OUR HAZARDOUS WEATHER OUTLOOK /PHLHWOCTP/. A BRIEF PERIOD OF ZONAL FLOW ALOFT AND WEAK SFC HIGH PRESSURE WILL BRING FAIR/MAINLY DRY WEATHER FOR THURSDAY...BEFORE A STRONG NRN STREAM SHORTWAVE AND ASSOCIATED 135 KT...300 MB JET DIVER SEWRD TO CARVE OUT A HIGH AMPLITUDE TROUGH ACROSS THE EASTERN THIRD OF THE U.S. FOR THE WEEKEND. EC SHOWS 500 MB TEMPS FROM THE OHIO VALLEY TO PENN DIVING TO PERHAPS THE COLDEST VALUES OF THE WINTER SEASON...OR AROUND -42C. 850 MB TEMPS MAY DROP TO -16-20C. WEST TO NW MEAN LLVL FLOW AND THE HIGHLY ANOMALOUS COLD AIR IMPLIES A SIGNIFICANT AND PROLONGED LES/UPSLOPE SNOW EVENT FOR THE WRN MTNS AND LAKE ERIE SNOWBELT COUNTIES. BROAD UPPER TROFFING OVER THE EASTERN U.S. WILL LEAD TO YET ANOTHER EAST COAST CYCLONE LATER IN THE WEEKEND. AT THIS POINT IN TIME...THE TRACK IS WELL OFFSHORE...AT LEAST CONCERNING AFFECTS ON PA. WRAP AROUND FLOW IS EVEN SIGNIFICANTLY NORTHERLY...PREVENTING WIDESPREAD LAKE EFFECT SNOW SHOWER ON THE BACK SIDE. IT HOWEVER WOULD SUPPORT AN EXTENDED COLD SPELL AS WE HEAD INTO MID FEBRUARY. && .AVIATION /22Z MONDAY THROUGH SATURDAY/... IFR/MVFR CONDITIONS WILL IMPROVE AS THE DRY AIR MOVES THRU FOR THE REMAINDER OF THE AFTERNOON AND WINDS SHIFT TO THE WEST. EXPECT THE FRONT TO CLEAR EASTERN AREAS THIS EVENING WITH WESTERLY WINDS INCREASING OVER THE REGION...GUSTING IN EXCESS OF 30KTS LATE TONIGHT INTO EARLY TUES OVER WESTERN HIGH TERRAIN. SOME PEAK GUSTS MAY EXCEED 40KTS. THE STRONG WINDS WILL DIRECT COLDER AIR INTO THE REGION WITH SOME SNOW SHOWERS LIKELY ALONG THE ALLEGHENY FRONT AND DOWNWIND OF LAKE ERIE. BLUSTERY POST-FRONTAL REGIME WILL DOMINATE INTO TUES WITH LOWEST CIGS OVR THE NRN AND WRN MTNS. OUTLOOK... TUE...MVFR CIGS NORTH/WEST...BECOMING VFR BY MID DAY. VFR ELSEWHERE WITH A SLOWLY DIMINISHING NW WIND ALL AREAS. WED-THU...VFR EARLY. IFR/SN DEVELOPING OVER THE SOUTHERN HALF OF THE AREA LATER WED INTO EARLY THU AS A LOW PRESSURE SYSTEM TRACKS OFF THE MID ATL COAST. FRI-SAT...MVFR WITH SNOW SHOWERS WEST. VFR EAST. && .CTP WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM 8 PM THIS EVENING TO 9 AM EST TUESDAY FOR PAZ004>006-010>012-017-018-024-025-033-034. && $$ SYNOPSIS...LA CORTE NEAR TERM...FITZGERALD/LA CORTE SHORT TERM...LA CORTE LONG TERM...LAMBERT/GARTNER AVIATION...LA CORTE
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
108 AM EST MON FEB 11 2013 .SYNOPSIS... A FRONTAL SYSTEM WILL MOVE THROUGH THE AREA LATER TODAY...FOLLOWED BY WINDY AND COLDER CONDITIONS TONIGHT INTO TUESDAY. LOW PRESSURE OVER THE GULF COAST IS EXPECTED TO TRACK TOWARD THE CAROLINAS ON WEDNESDAY...BEFORE MOVING OFF THE SOUTHERN MID-ATLANTIC COAST WEDNESDAY NIGHT. IT MAY GET CLOSE ENOUGH TO AFFECT SOUTHERN PENNSYLVANIA. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... EVENING SATL LOOP SHOWING UPPER LOW LIFTING NE INTO S MINNESOTA. ASSOCIATED LL JET AND PLUME OF MOISTURE AHEAD OF THIS FEATURE CAN BE TRACED ALL THE WAY BACK TO THE EASTERN PACIFIC. ALTHOUGH PWATS ALONG THIS LL JET ARE 2-3 STD ABV NORMAL...IT SHOULD PASS RATHER QUICKLY THRU CENTRAL PA LATE TONIGHT AND EARLY MON AM. THEREFORE... PRECIP AMTS NOT EXPECTED TO BE HEAVY. 18Z GEFS MEAN QPF RANGES FROM ARND A QUARTER INCH ACROSS THE NORTH CENTRAL MTNS...TO ALMOST 0.75 INCHES ACROSS LANCASTER CO. ALTHOUGH SURGE OF WARM AIR ALOFT ASSOC WITH LL JET SHOULD ENSURE LIQUID PRECIP...MDL SOUNDINGS CONTINUE TO INDICATE ENOUGH COLD AIR NR GROUND LVL FOR A PERIOD OF FZRA. 00Z PIT SOUNDING SHOWS PLENTY OF DRY AIR IN THE LOW LVLS. SO EVEN THOUGH TEMPS ARE CURRENTLY ABV FREEZING OVR MOST OF CENTRAL PA UNDER WAA AND OVERCAST SKIES...EXPECT EVAPORATIVE COOLING TO LOWER SFC TEMPS JUST BLW 0C AS RAIN ARRIVES OVERNIGHT. REGIONAL RADAR AND LATEST RAP INDICATE FZRA/RA WILL OVERSPREAD THE W MTNS ARND MIDNIGHT...THEN SPREAD INTO THE SUSQ VALLEY BY 3 OR 4 AM. SREF/GEFS AND 18Z OPER RUNS ALL POINT TOWARD A MARGINAL ICING EVENT...WITH TEMPS VERY CLOSE TO FREEZING OVERNIGHT...THEN RISING BY DAWN. BY 12Z...BULK OF MDL DATA INDICATES ONLY THE HIGH TERRAIN OF NORTH CENTRAL PA WILL REMAIN BLW FREEZING. SO...I ENVISION WE WILL BE ABLE TO CHIP AWAY AT THE ADVISORY FROM SW TO NE DURING THE EARLY AM HOURS. GIVEN THE MARGINAL TEMPS...EXPECT ICE ACCRETION RATES TO BE LOW AND NOT APPROACH THE LIQUID PRECIP FORECAST MENTIONED ABOVE. ICE AMOUNTS SHOULD RANGE FROM A TRACE TO A TENTH OF AN INCH...WITH THE LEAST AMTS WEST OF THE ALLEGHENIES ARND CONFLUENCE. && .SHORT TERM /7 AM THIS MORNING THROUGH 6 PM TUESDAY/... SHORT RANGE OPERATIONAL MODELS ARE PRETTY AGREEABLE WITH THE LL JET AND PLUME OF ANOMALOUS PWATS SWEEPING EAST OF THE AREA BTWN 12Z-15Z...CAUSING RA/FZRA TO TAPER OFF. ANY ZR ONGOING AFTER 6AM SHOULD QUICKLY CHANGE TO PLAIN RAIN AS TEMPS RISE INTO THE LOW TO MID 30S BY MID MORNING. THE DRY SLOT SOUTH OF UPPER LOW SHOULD WORK INTO CENTRAL PA BY LATE AM...SHUTTING THE PRECIP OFF AND BRINGING PARTIAL CLEARING...ESP DOWNWIND /EAST/ OF THE ALLEGHENIES. MDL DATA INDICATES MUCH OF CENTRAL PA WILL BRIEFLY BREAK INTO THE WARM SECTOR MON AFTN WITH GEFS 925 TEMPS SUPPORTIVE OF HIGHS AOA 50F ACROSS SOUTHERN PA. BY LATE IN THE DAY...SFC COLD FRONT WILL PUSH INTO WESTERN PA... ACCOMPANIED BY SCT -SHRA/SN AND A GUSTY WIND SHIFT FROM SW TO WEST. DON/T EXPECT ANY SNOW ACCUMS...AS SFC TEMPS SHOULD REMAIN WELL ABV FREEZING THRU EARLY EVENING...EVEN OVR THE NW MTNS. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... A FAIRLY AMPLIFIED SPLIT-FLOW UPPER PATTERN IS FORECAST TO PERSIST THROUGH THE LONG TERM PERIOD ACROSS MUCH OF NORTH AMERICA. NUMEROUS NORTHERN AND SOUTHERN STREAM SHORTWAVES WILL BRING SEVERAL CHANCES FOR PCPN TOWARD PA DURING THE PERIOD... THOUGH AT THIS POINT IN TIME SIGNIFICANT PCPN EVENTS DO NOT APPEAR DESTINED FOR THE COMMONWEALTH...AT LEAST NOT DIRECTLY. AN ABUNDANCE OF SRN STREAM FLOW WILL BRING INTRUSIONS OF ABOVE FREEZING TEMPERATURES TO THE REGION...FURTHER COMPLICATING THE LONG TERM FORECAST DETAILS. PHASING ENERGY MAY SUPPORT A NEARLY FULL LATITUDE TROF SPREADING EASTWARD INTO THE EASTERN U.S. BY NEXT WEEKEND...LEADING TO PERHAPS THE HIGHEST POTENTIAL OF SIGNIFICANT PCPN POTENTIAL IN THE LONG TERM PERIOD. LAKE EFFECT SHOWERS WILL BE ONGOING IN THE WEAK OF MONDAYS SYSTEM/COLD FROPA. A WEAK RIDGE OF HIGH PRESSURE SLIDES NE ACROSS THE STATE TUESDAY NIGHT BRINGING AN END TO THE SNOW SHOWERS. THE NEXT SYSTEM HEADED OUR WAY FOR WEDNESDAY AFTERNOON INTO EARLY THURSDAY IS TIED TO A RATHER VIGOROUS SOUTHERN STREAM JET EXIT REGION. THE NOSE OF THIS 140 KT JET WILL LIFT TWD THE CENTRAL APPALACHIANS DURING THE DAY WEDNESDAY. DETAILS OF THE EXACT PRESSURE PATTERN AND TIMING OF A WEAK SFC LOW WEST OF THE APPALACHIANS PER THE 06Z NAM /AND SECONDARY DEVELOPMENT NEAR THE VA COAST/ ARE STILL A BIT SKETCHY. LATEST...00Z GEFS IS A BIT OMINOUS AS ABOUT 20-25 PERCENT OF ITS MEMBERS CONTAIN AROUND AN INCH OF QPF IN THE FORM OF SNOW LATE WEDNESDAY INTO THURSDAY. SOME VARIATIONS IN THE TIMING OF THIS PRECIP ARE ALSO NOTED. MEAN TRACK OF THE 850 MB LOW CENTER ON THE GEFS TAKES IT ACROSS ERN VA AND SOUTHERN DELAWARE ALONG WITH A SLIGHTLY ANOMALOUS EASTERLY WIND AT THAT PRESSURE LEVEL. THE GEFS CONSENSUS QPF IS AROUND 0.25 INCH FOR THE LOWER SUSQ VALLEY WITH SHARPLY LESSER AMOUNTS TO THE NW. PAINTED HIGH CHC TO LOW LIKELY POPS INTO OUR GRIDDED DATABASE FOR THE SE THIRD TO HALF OF THE CWA...CENTERED ON WED NIGHT WITH A RESULTANT 1-3 INCHES OF SNOW. THIS SYSTEM BEARS CLOSE WATCHING AS ANY INTERACTION WITH AN UPSTREAM WAVE IN THE NRN BRANCH COULD HELP TO INVIGORATE THE COASTAL LOW AND LLVL EASTERLY FLOW BRINGING MORE SNOW TO THE SERN ZONES...AND SPREADING LIGHT SNOWS OVER THE I-80 CORRIDOR. ITS CURIOUS TO NOTE THAT THE 00Z OPERATIONAL EC /THAT INITIALLY HANDLED THE RECENT NEW ENGLAND BLIZZARD MUCH BETTER THAN THE U.S MODELS/ IS 12-18 HOURS FASTER...AND A FEW HUNDRED KM FURTHER SOUTH WITH THE SFC/UPPER WAVE TRACK...AND JUST BRUSHES THE MASON/DIXON LINE WITH SOME LIGHT SNOW AT THE NRN EDGE OF THE PRECIP SHIELD. THE AFOREMENTIONED BROAD LONGWAVE TROF MOVED ACROSS THE REGION THURSDAY INTO NEXT WEEKEND...WITH A RETURN OF ARCTIC AIR. WITH THE TROF WILL BE SIGNIFICANT NRN STREAM ENERGY AND AT LEAST ONE CLIPPER SYSTEMS MOVING ACROSS NW PA ON FRIDAY WITH LE SNOW SHOWERS PERSISTING INTO NEXT WEEKEND. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... SIGNIFICANT CHANGES WERE MADE TO THE 06Z TAFS. PCPN HAS ARRIVED A LITTLE EARLIER THAN FCST...AND TIMING OF THICKENING CLOUDS LAST EVE HAS PRESERVED TEMPS MAINLY ABV 32F. IN ADDITION...DEWPT DEPRESSION ARE RUNNING 10-15 DEGREES. THEREFORE...THERMAL PROFILES ARE NO LONGER THAT FAVORABLE FOR -FZRA AND WOULD TEND TO LEAN TOWARD -RA OR -PL PTYPES DUE TO EVAPORATIVE COOLING IN THE LOW LEVELS. REMOVED -FZRA AND WENT WITH PLAIN RAIN FOR PREVAILING PRES WX...WITH SOME SITES REPORTING "UP" (SLEET) FOR A BRIEF PERIOD. KEPT LLWS AS 40-50KT SWLY LLJ TRANSLATES EWD AHEAD OF THE APPROACHING COLD FRONT. VFR CIGS SHOULD DROP TO MVFR WITH GUIDANCE SUGGESTING AN OUTSIDE CHC FOR IFR AT LNS/MDT. SFC WINDS WILL SHIFT FROM S/SE TO WSW LATER TDY...VEERING MORE TO THE WEST AND INCREASING INTO TONIGHT. OUTLOOK... TUE...MVFR CIGS NORTH/WEST. VFR EAST. WED...DEVELOPING VFR TO START THE DAY. LOWER CONDITIONS POSSIBLE OVER THE SOUTH BY LATE DAY AS A STORM SYSTEM SKIRTS THE REGION. THUR...MAINLY VFR. FRI...MVFR/IFR DEVELOPING OVER THE WEST AND CENTRAL TERMINALS. VFR EAST. WINDY. && .CTP WATCHES/WARNINGS/ADVISORIES... FREEZING RAIN ADVISORY UNTIL 9 AM EST THIS MORNING FOR PAZ004>006-010>012-017>019-024>028-033>037-041-042-045-046- 049>053-056>059-063>066. && $$ SYNOPSIS...STEINBUGL NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD/LA CORTE LONG TERM...LAMBERT/GARTNER AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
947 PM EST TUE FEB 12 2013 .SYNOPSIS... A SURFACE LOW WILL APPROACH THE CAROLINAS TOMORROW MORNING BRINGING CLOUDY SKIES AND PRECIPITATION TO THE AREA. AS THE LOW LIFTS NORTHEAST...HIGH PRESSURE WILL BUILD BACK INTO THE AREA LATE WEDNESDAY AND LINGER INTO THE WEEKEND. && .NEAR TERM /THROUGH WEDNESDAY/... 930 PM UPDATE...21Z SREF AND 01Z RAP SEEM TO HAVE PICKED UP ON THE FACT THAT MOST OF THE PRECIP THIS EVENING HAS SCOOTED BY TO OUR SOUTH...AT LEAST IN TERMS OF ACCUMULATION. MOST OBS SITES IN THE CWFA HAVE REPORTED RAIN AT SOME POINT SO FAR...SO LLVL DRY AIR IS NO LONGER MUCH OF A PROBLEM. DESPITE KEEPING THE HEAVIER PRECIP ALONG THE LOWER PIEDMONT AND MIDLANDS...THE MODELS SHOW BANDS OF LIGHT PRECIP TRANSITING THE AREA MOST OF THE NIGHT. KEPT CATEGORICAL POPS THOUGH CHANGED COVERAGE WORDING TO PERIODS WHICH IS MORE APPROPRIATE. SREF PROBS OF 100 J MUCAPE NEAR 100 PCT IN 09-12Z TIMEFRAME IN OUR SOUTH...REASONABLY CONSISTENT WITH PREVIOUS EXPECTATIONS. A FEW CELLS ARE SEEN OVER ALABAMA WHERE SAME CONDITION PRESENT ON 03Z PROG. WILL KEEP THUNDER WORDING AS-IS. MIN TEMPS WERE REVISED SLIGHTLY PER EVENING OBS...THOUGH LATEST GUIDANCE HAS NOT DEVIATED MUCH FROM AFTN PACKAGE. SREF TRENDS FOR THE DEPARTURE OF PRECIP TOMORROW SUPPORT MAINTAINING LKLY POPS THRU MIDDAY...THUS NO CHANGES MADE TO FCST. AT 230 PM EST TUESDAY...AN UPPER LOW OVER THE SOUTHERN PLAINS WILL FILL TONIGHT WHILE ITS REMAINING TROUGH MOVES TO THE MS RIVER VALLEY. THE TROUGH WILL MOVE TO THE SOUTHERN APPALACHIANS ON WEDNESDAY. MOIST ISENTROPIC UPGLIDE WILL SET UP THIS EVENING AHEAD OVER A WARM FRONT NEAR THE GULF COAST...AHEAD OF A SURFACE WAVE THAT WILL MOVE NE ACROSS THE DEEP SOUTH. THE NAM SOUNDING IS COOL ENOUGH IN THE NORTHERN MOUNTAINS FOR SOME SNOW LATE TONIGHT...BUT THE GFS HAS MORE OF A WARM NOSE...IS SLIGHTLY WARMER AT THE SURFACE...AND ITS MOIST LAYER IS NOT COLD ENOUGH FOR ICE NUCLEATION. A BLEND OF THE TWO WAS USED TO PRODUCE THIS FORECAST...AND SUPPORTED ALL RAIN THERE. MINIMUM SURFACE TEMPERATURES WILL RUN SEVERAL CATEGORIES ABOVE NORMAL UNDER CLOUD COVER...BUT A LOCATION OR TWO IN THE NORTHERN NC MOUNTAINS WILL APPROACH FREEZING. AT THIS TIME THE FORECAST IS ABOVE FREEZING AT ALL SITES...AND NO FREEZING RAIN IS BEING CARRIED IN THE FORECAST. RAIN ASSOCIATED WITH THIS LIFT IS EXPECTED TO FROM IN SITU COLD AIR DAMMING OVER OUR AREA ON WEDNESDAY...LIMITING WARMING. AS THE SURFACE WAVE MOVES BY IN THE AFTERNOON...DRIER AIR WILL WORK INTO THE AREA FORM THE SW...LOWERING THE CHANCE OF PRECIPITATION. MOIST NW FLOW BEHIND THE WAVE WILL SUPPORT LINGERING SHOWERS IN THE NC MOUNTAINS LATE IN THE DAY... WHERE COLD ADVECTION WILL SUPPORT A CHANGE OVER TO SNOW AT HIGHER ELEVATIONS. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... AS OF 245 PM TUESDAY...SHORT WAVE AND SFC LOW PRESSURE MOVE NE AWAY FROM THE AREA WED NITE WITH NEARLY ZONAL FLOW AND SFC HIGH PRESSURE BRIEFLY BUILDING IN FOR THU. GUIDANCE STILL HAS NW FLOW AND LINGERING LOW LEVEL MOISTURE ACROSS THE NC MTNS WED NITE. HOWEVER... THE GUIDANCE IS NOT AS BULLISH ON PRECIP. STILL...THERE LOOKS TO BE ENUF LIFT...MOISTURE AND CAA FOR A PERIOD OF NW FLOW SNOW DURING THE EVENING WHICH THEN TAPERS OFF AFTER MIDNIGHT. IN FACT...MOISTURE DIMINISHES SO QUICKLY FROM TOP DOWN THAN THE PRECIP COULD END AS A PERIOD OF FREEZING RAIN OR DRIZZLE. EITHER WAY...IT LOOKS LESS LIKELY FOR ANY SIGNIFICANT PRECIP OF ANY KIND OVERNIGHT...WITH AROUND AN INCH OF SNOW EXPECTED IN THE HIGHER ELEVATIONS OF THE NRN MTNS AND UP TO AN INCH IN THE HIGHER ELEVATIONS OF THE SMOKIES. EXPECT CLOUDS TO LINGER THRU THE NIGHT ACROSS THE MTNS EVEN WHERE PRECIP IS LIMITED. WINDY CONDITIONS DURING THE EVENING DIMINISH OVERNIGHT AS WELL. LOWS WILL BE NEAR NORMAL. ELSEWHERE...SKIES CLEAR AND PRECIP ENDS QUICKLY DURING THE EVENING WITH MOSTLY CLEAR SKIES OVERNIGHT. BREEZY CONDITIONS DURING THE EVENING DIMINISH OVERNIGHT AS WELL. LOWS WILL BE A FEW DEGREES ABOVE NORMAL. SKIES CLEAR ACROSS THE NC MTNS THU MORNING WITH SUNNY SKIES ELSEWHERE THRU THE DAY. BREEZY SW WINDS DEVELOP DURING THE AFTERNOON WITH HIGHS UP TO 5 DEGREES ABOVE NORMAL ALL AREAS. WITH DOWNSLOPE FLOW WARMING TEMPS INTO THE MID 50S TO LOW 60S OUTSIDE THE MTNS. A DEEP TROF BEGINS TO DEVELOP ACROSS THE CENTRAL AND ERN US ON FRI AS A WEAK SHORT WAVE MOVES OVER THE AREA. THIS SHORT WAVE PUSHES A WEAK DRY COLD FRONT ACROSS THE AREA FRI. THERE WILL BE ENUF MOISTURE FOR INCREASING CLOUDS ACROSS THE MTNS AND NC FOOTHILLS/PIEDMONT FRI WITH MOSTLY SUNNY SKIES ELSEWHERE. EXPECT BREEZY SW WINDS FRI MORNING TO BECOME W TO NW BY AFTERNOON. LOWS THU NITE WILL BE A FEW DEGREES ABOVE NORMAL...WHILE HIGHS FRI WILL BE NEAR NORMAL MTNS AND UP TO 5 DEGREES ABOVE NORMAL ELSEWHERE. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AS OF 225 PM TUESDAY...THE GLOBAL MODELS CONTINUE TO DEPICT A BRIEF PATTERN CHANGE OVER THE WEEKEND...AS A SERIES OF SHORT WAVE TROUGHS DIVING OUT OF THE NORTHERN CONUS CARVE OUT A DEEP LONG WAVE TROUGH OVER THE EASTERN STATES DURING THE WEEKEND. THIS PATTERN WILL BRING MUCH COOLER WEATHER TO THE REGION...AND POSSIBLY PERIODS OF NORTHWEST FLOW SNOW SHOWERS TO THE MTNS. A POTENT SHORT WAVE IS EXPECTED TO MOVE OVER THE SOUTHEAST STATES IN THE SATURDAY/SAT NIGHT TIME FRAME. IT IS INTERESTING THAT THE MODELS SUGGEST THAT THIS FEATURE WILL TAKE ON A NEGATIVE TILT AFTER IT LIFTS AWAY FROM THE COAST...RESULTING IN RAPID CYCLOGENESIS. THIS SCENARIO WOULD HAVE NO EFFECT ON THE SENSIBLE WEATHER OVER OUR AREA...BUT IF THE TRANSITION TO A NEGATIVE TILT OCCURS SOONER...THINGS COULD GET INTERESTING. OTHERWISE...THE TROUGH AXIS WILL SHIFT OFF THE EAST COAST BY THE END OF THE WEEKEND...ALLOWING FOR A RETURN TO NEAR SEASONAL TEMPERATURES BY MONDAY/TUESDAY. THE GLOBAL MODELS ARE IN QUITE GOOD AGREEMENT THAT LARGE SCALE HEIGHT FALLS WILL BE OCCURRING ACROSS MUCH OF THE EASTERN HALF OF THE CONUS BY THE END OF THE PERIOD...AS A MAJOR SHORT WAVE TROUGH DIVES OUT OF THE CENTRAL/NORTHERN ROCKIES. AS A RESULT...THE GFS AND ECMWF ARE DEPICTING A RATHER WET DAY 7 ACROSS THE SOUTHEAST...SO CHANCE POPS HAVE BEEN INTRODUCED. ATTM...IT APPEARS THAT THE PATTERN WILL BE SUCH THAT WINTRY PRECIP WILL NOT BE A SIGNIFICANT CONCERN. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... AT KCLT...LIGHT RAIN FALLING FROM MIDLEVEL VFR CIG AS OF 00Z WITH CALM WINDS. AS DEVELOPING SFC LOW PRESSURE MOVES NORTHEASTWARD FROM THE CENTRAL GULF COAST TONIGHT...LOW LEVEL WARM AIR AND MOISTURE ADVECTION WILL BRING INCREASINGLY WIDESPREAD RAIN AND LOWERING CIGS. UPSTREAM OBS AND SHORT TERM GUIDANCE WOULD POINT TO MVFR CIGS AND VSBY FOR MOST OF THE NIGHT...ONCE ENOUGH RAIN MOVES IN TO MOISTEN THE LOW LEVELS. THE LLVL LIFT PEAKS LATE TONIGHT AND EARLY WED AND GUIDANCE BRINGS IN IFR CIGS FOR A TIME. THE LOW PRESSURE TRACKS THROUGH THE SRN APPALACHIANS BY WED AFTN TAKING THE FORCING WITH IT...AT WHICH TIME RESTRICTIONS WILL BEGIN TO LIFT. SHOULD BE BACK TO MVFR BY EARLY AFTN AS THE RAIN TAPERS OFF WITH VFR CLOUDS BEGINNING TO SCATTER BY 21Z. SOME 20 KT OR STRONGER WINDS WILL BE NOT TOO FAR OFF THE SFC AND ONCE CLOUDS START TO BREAK UP THESE WINDS SHOULD BE REACHED BY MIXING. NORTHERLY WINDS TONIGHT WILL SWING SOUTHEAST BY MORNING AND THEN SOUTHWEST AS THE LOW MOVES PAST. ELSEWHERE...VFR THIS EVENING AHEAD OF RAINFALL MOVING IN FROM THE SOUTHWEST. RAIN WILL INITIALLY BE RATHER LIGHT AS IT FALLS INTO DRY NEAR SFC AIR...BUT INCREASING MOISTURE ADVECTION ALOFT AHEAD OF THE SFC LOW WILL BOTH REDUCE EVAPORATION AND INCREASE RAIN PRODUCTION. CIGS SHOULD EASILY GO MVFR BY LATE EVENING OVER THE SOUTHERN SITES AND BY EARLY MORNING TO THE NORTH. FURTHER DEEPENING MOISTURE EXPECTED TO LOWER CIGS TO IFR CLOSER TO DAYBREAK...WITH SOME LIGHT FOG REDUCING ALREADY RAIN-LIMITED VSBY. CIGS WILL PROBABLY DOMINATE THE RESULTING CATEGORY HOWEVER. RAIN EXPECTED TO TAPER OFF BY LATE MORNING OVER THE SOUTH WITH THE BACK EDGE PROGRESSING NORTHWARD FROM THERE...FOLLOWED BY A SIMILAR CLEARING TREND. WEAK NORTHERLY WINDS TONIGHT WILL GENERALLY VEER AS THE LOW APPROACHES AND THEN PASSES SITES...BECOMING SOUTHWEST BY THE END OF THE PERIOD AT ALL SITES /EXCEPT KAVL WHICH GOES NORTHWEST/. GUSTS INTO THE 20-30 KT RANGE ARE LIKELY WED AFTN ESPECIALLY IN THE MTNS AND WESTERN UPSTATE WHERE COLDER AIR WILL BE FIRST TO MOVE IN ALOFT AND ENHANCE MIXING POTENTIAL. OUTLOOK...LOW PRESSURE WILL EXIT TO THE EAST BY WEDNESDAY NIGHT...ENDING RESTRICTIVE CIGS AND VSBYS. HIGH PRESSURE IS EXPECTED TO BRING BETTER CONDITIONS FOR THURSDAY. CONFIDENCE TABLE 03-09Z 09-15Z 15-21Z 21-03Z KCLT HIGH 80% LOW 57% HIGH 87% HIGH 87% KGSP MED 77% LOW 55% HIGH 83% HIGH 91% KAVL MED 71% MED 67% HIGH 92% HIGH 95% KHKY HIGH 94% MED 76% HIGH 90% MED 66% KGMU MED 75% MED 60% HIGH 85% HIGH 91% KAND MED 67% MED 69% HIGH 88% HIGH 87% 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...NONE. SC...NONE. && $$ SYNOPSIS...JPT NEAR TERM...JAT/WIMBERLEY SHORT TERM...RWH LONG TERM...JDL AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
1142 PM CST SUN FEB 10 2013 .DISCUSSION... SEE AVIATION SECTION. && .AVIATION... VFR CONDITIONS WILL PREVAIL AT THE TAF SITES OVERNIGHT THROUGH MONDAY AFTERNOON. HIGH CLOUD COVERAGE WILL INCREASE OVERNIGHT WHILE PATCHY MID-LEVEL CLOUDS DEVELOP. A FEW SPRINKLES OR A BRIEF LIGHT RAIN SHOWER ARE A POSSIBILITY AT KBBD...KJCT AND KSOA. A BACK DOOR TYPE COLD FRONT WILL SAG SOUTH ACROSS THE BIG COUNTRY OVERNIGHT...AND SHOULD BECOME NEARLY STATIONARY ACROSS THE NORTHERN CONCHO VALLEY AND HEARTLAND AREAS ON MONDAY. AT KABI...WINDS WILL BECOME EAST OVERNIGHT AND REMAIN MOSTLY FROM THE EAST ON MONDAY. LIGHT WINDS AT THE OTHER TAF SITES OVERNIGHT WILL BECOME EAST TO SOUTHEAST ON MONDAY. CLOUD CEILINGS WILL DECREASE MONDAY EVENING AND MONDAY NIGHT...AND ARE EXPECTED TO BE IN THE RANGE OF 2500-3500 FT DURING THE FINAL 4-6 HOURS OF THE TAF PERIOD. SCATTERED RAIN SHOWERS ARE POSSIBLE MONDAY EVENING AND MONDAY NIGHT...AND CARRYING VICINITY SHOWERS IN THE AREA TAFS DURING THAT TIME. 19 && .PREV DISCUSSION... /ISSUED 547 PM CST SUN FEB 10 2013/ DISCUSSION... SEE AVIATION SECTION. AVIATION... VFR CONDITIONS WILL PREVAIL AT THE TAF SITES TONIGHT AND MONDAY. SOME INCREASE IN HIGH CLOUD COVERAGE IS EXPECTED TONIGHT. SOME MID-LEVEL CLOUD DEVELOPMENT IS EXPECTED ACROSS SOUTHERN SECTIONS OF WEST CENTRAL TEXAS LATE TONIGHT AND MONDAY. A FEW SPRINKLES OR PERHAPS A LIGHT RAIN SHOWER IS POSSIBLE MONDAY...TO THE EAST OF THE KJCT AND KBBD TERMINALS. WINDS WILL BE LIGHT AND VARIABLE TONIGHT. EAST-SOUTHEAST WINDS WILL DEVELOP ON MONDAY AND INCREASE TO 8-12 KT. 19 PREV DISCUSSION... /ISSUED 349 PM CST SUN FEB 10 2013/ SHORT TERM... RELATIVELY QUIET WEATHER CONDITIONS IN THE SHORT TERM PERIOD. A WEAK FRONT WILL ENTER THE BIG COUNTRY LATE TONIGHT BUT WILL WASH OUT ACROSS THE AREA ON MONDAY. SUBTROPICAL JET WILL CONTINUE TO FEED MID AND HIGH LEVEL MOISTURE FROM THE SOUTHWEST ACROSS MAINLY SOUTHERN SECTIONS OVERNIGHT. THE NAM CONTINUES TO SHOW SOME LIGHT RAIN SHOWERS DEVELOPING OVER EXTREME SOUTHEAST COUNTIES ON MONDAY IN AN AREA OF WEAK ISENTROPIC ASCENT/WAA. 3KM WRF AND LATEST RUC ALSO HINTING AT THIS POSSIBILITY SO WILL KEEP SLIGHT CHANCE POPS INTACT THIS FORECAST CYCLE. CLOUD COVER WILL LIMIT COOLING ACROSS SOUTHEAST SECTIONS TONIGHT WITH LOWS MAINLY IN THE LOWER 40S. LIMITED CLOUD COVER...LIGHT WINDS AND A DRY AIRMASS WILL ALLOW TEMPS TO COOL INTO THE LOW TO MID 30S ACROSS THE REMAINDER OF THE AREA. MID AND HIGH CLOUDS WILL CONTINUE TO INCREASE ON MONDAY WITH AFTERNOON HIGHS RANGING FROM THE LOW TO MID 60S NORTH TO THE MID AND UPPER 60S SOUTH. 24 LONG TERM... UPPER LOW NEAR THE FOUR CORNERS LATE MONDAY WILL WILL DIG SOUTHEAST TUESDAY INTO NEW MEXICO. SURFACE TO 850MB LAYER WILL QUICKLY SATURATE OVER THE ENTIRE CWA BY MIDNIGHT MONDAY CONCOMITANT WITH AN INTENSIFYING LLJ...40-50KT CENTERED OVER THE SOUTHWESTERN CWA. THE HEAVIEST RAINFALL ACCUMULATION CHANCES WILL BE OVER THE BIG COUNTRY ON THE NOSE OF THE LOW LEVEL JET BEGINNING AROUND MIDNIGHT MONDAY AND LASTING INTO TUESDAY MORNING. HAVE INCLUDED THE MENTION OF CONVECTIVE ACTIVITY MONDAY NIGHT THROUGH TUESDAY AS THE COLD FRONT/DRYLINE MOVES EAST THROUGH THE FORECAST AREA. LATEST SPC CONVECTIVE OUTLOOK MENTIONS VIA A SEE TEXT THE POSSIBILITY FOR LARGE HAIL FOR OUR AREA BASED ON SUFFICIENT INSTABILITY AND SHEAR VALUES FOR ELEVATED SUPERCELLS...AS REFLECTED IN THE LATEST FORECAST SOUNDINGS...WILL CONTINUE TO EVALUATE THIS POSSIBILITY. PRECIPITATION CHANCES WILL BE CONFINED TO OUR EASTERN TIER OF COUNTIES BY TUESDAY AFTERNOON WITH PRECIPITATION ENDING OVER ALL OF THE FORECAST AREA BY TUESDAY EVENING. TUESDAY MORNING LOWS WILL RANGE FROM THE LOWER 40S TO AROUND 50 DEGREES AND TUESDAY AFTERNOON HIGHS WILL RANGE FROM THE MID 50S TO THE MID 60S UNDER CLOUDY SKIES. AFTERNOON HIGHS AND MORNING LOWS WILL REMAIN NEAR CLIMO THROUGH THE COMING WEEKEND...GENERALLY IN THE LOWER 60S FOR HIGHS AND THE MID 30S FOR LOWS. THE NEXT COLD FRONTAL PASSAGE WILL BE LATE THURSDAY WITH LITTLE IMPACT ON THE FORECAST AREA. 15 && .PRELIMINARY POINT TEMPS/POPS... ABILENE 33 64 46 58 32 / 0 5 60 40 10 SAN ANGELO 34 70 50 64 35 / 0 10 50 10 5 JUNCTION 43 68 45 66 35 / 0 20 50 20 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1113 PM CST SUN FEB 10 2013 .UPDATE... ALTHOUGH THERE IS DRY AIR IN THE LOWER 8000 FEET OF THE ATMOSPHERE...RADAR RETURNS HAVE INCREASED TO THE POINT WHERE SOME SPRINKLES OR PATCHES OF LIGHT RAIN ARE LIKELY OVERNIGHT ACROSS THE AREA SOUTH OF A COMANCHE TO MCKINNEY TO COOPER LINE. THUS HAVE ADDED A 10 PERCENT CHANCE OF LIGHT RAIN IN THOSE AREAS. 58/91 && .AVIATION... VFR CONDITIONS ARE EXPECTED THROUGH 06Z TUESDAY. LIGHT WEST TO NORTHWEST WINDS THIS EVENING WILL BECOME NORTHEAST AT 5 TO 10 KNOTS BEFORE DAYBREAK AND EASTERLY MONDAY AFTERNOON. THERE WILL BE SOME LOW RAIN CHANCES LATE MONDAY AFTERNOON THROUGH THE EVENING IN THE METROPLEX...BUT THE CHANCES ARE NOT HIGH ENOUGH TO MENTION IN THE TAFS. RAIN CHANCES MONDAY AFTERNOON IN THE WACO AREA MAY PROMPT THE ADDITION OF VCSH WITH THE 03Z UPDATES. RAIN CHANCES WILL IMPROVE AREA WIDE AFTER MIDNIGHT. 58 && .PREV UPDATE... .UPDATE... ONLY SOME MINOR CHANGES NEEDED TO THE CURRENT FORECAST. WATER VAPOR IMAGERY SHOWS THE POWERFUL UPPER STORM THAT BROUGHT LAST NIGHTS WEATHER NOW MOVING INTO THE UPPER MIDWEST. THERE IS ANOTHER UPPER TROUGH OVER THE WESTERN US AND THIS IS HELPING KEEP NORTH TEXAS IN A FAST SOUTHWEST FLOW ALOFT. FORT WORTH RAOB SAMPLED A 150KT UPPER JET AT 230MB. THERE IS SOME MOISTURE ALSO STREAMING OVERHEAD AS INDICATED BY THE PARTIAL CLOUD COVER. FARTHER SOUTH...MOISTURE IS A LITTLE BETTER AND RAP FORECAST SOUNDINGS ACTUALLY INDICATE SOME SATURATION ABOVE 600MB. THIS IS RESULTING IN SOME LIGHT PRECIPITATION ACROSS THE FAR SOUTHERN COUNTIES...HOWEVER GIVEN THE DRY AIR BENEATH IT...MOST OF THE RETURNS ON THE RADAR ARE VIRGA. NOT EXPECTING ANY PRECIP TO REACH THE GROUND OVERNIGHT TONIGHT. BETTER RAIN CHANCES WILL ARRIVE LATE TOMORROW AND PERSIST INTO TUESDAY. CHANGES TO CURRENT FORECAST WERE LIMITED TO HOURLY TEMPERATURES AND SKY COVER. DUNN && .PREV DISCUSSION... /ISSUED 348 PM CST SUN FEB 10 2013/ AFTERNOON WATER VAPOR SATELLITE IMAGERY INDICATED A POWERFUL UPPER LOW OVER THE NORTH PLAINS WITH A STRONG SHORTWAVE TROUGH LOCATED OVER EASTERN NEVADA. AFTERNOON SURFACE OBSERVATIONS SHOWED WESTERLY WINDS OVER ALL OF NORTH AND CENTRAL TX...THE RESULT OF A PACIFIC TYPE COLD FRONT THAT MOVED THROUGH OVERNIGHT AND WAS ACCOMPANIED BY A LINE OF STRONG TO SEVERE THUNDERSTORMS. PERSISTENT WESTERLY FLOW HAS ADVECTED A VERY DRY AIR MASS OVER NORTH TX THIS AFTERNOON WITH DEW POINTS OBSERVED IN THE TEENS WEST OF THE INTERSTATE 35 CORRIDOR AND IN THE UPPER 20S TO LOWER 30S TO THE EAST. PERSISTENT CLOUD COVER HAS HELD TEMPERATURES IN THE MID 60S FOR MOST LOCATIONS...DESPITE THE DRY AIR IN PLACE. TONIGHT THROUGH WEDNESDAY...THE NEVADA SHORTWAVE TROUGH WILL CONTINUE TO SINK SOUTH-SOUTHEAST THROUGH TOMORROW MORNING AS IT MERGES WITH A SECOND...COMPACT AND VERY FAST MOVING...TROUGH COMING OUT OF WESTERN CANADA. AS THIS TROUGH APPROACHES THE REGION IT WILL SPREAD LARGE SCALE FORCING FOR ASCENT OVER THE CWA...RESULTING IN AN INCREASE IN LOW LEVEL CLOUD COVER FROM SOUTHEAST TO NORTHWEST THROUGH MONDAY AFTERNOON. THIS MOISTURE RETURN WILL LIKELY RESULT IN ISOLATED RAIN SHOWERS DEVELOPING ALONG AND SOUTHEAST OF AN ATHENS TO GATESVILLE LINE MONDAY MORNING...SPREADING NORTHWEST TOWARDS THE DFW METROPLEX BY MONDAY AFTERNOON. DUE TO THE VERY DRY AIR CURRENTLY IN PLACE...THINK THAT RAINFALL WILL BE LIGHT IN NATURE...WITH INITIAL RAIN SHOWERS WORKING TO SATURATE THE NEAR SURFACE LAYER FROM THE TOP DOWN RESULTING IN VIRGA AND LOWERING CLOUD DECKS. HIGHS ON MONDAY WILL LIKELY STRUGGLE TO REACH 60 DEGREES FOR THE SOUTHEASTERN PORTIONS OF THE CWA WITH MOSTLY CLOUDY SKIES AND ISOLATED RAIN SHOWERS TO CONTEND WITH. ELSEWHERE HIGHS WILL LIKELY ONLY REACH THE LOWER 60S. ISOLATED RAIN SHOWERS WILL SPREAD NORTH OVER THE ENTIRE CWA MONDAY EVENING AS THE TROUGH BEGINS TO MOVE EAST-NORTHEAST TOWARDS THE SOUTH PLAINS. MOST GUIDANCE BRINGS NUMEROUS RAIN SHOWERS OVER NORTH AND CENTRAL TX LATE MONDAY NIGHT AND INTO TUESDAY MORNING AS THE BEST LARGE SCALE FORCING FOR ASCENT MOVES OVER NORTH TX. DID NOT MAKE ANY REAL CHANGE TO THE PREVIOUS FORECAST DURING THIS PERIOD AS LIKELY /60 TO 70/ POPS SEEM APPROPRIATE FOR THE EXPECTED COVERAGE OF RAIN SHOWERS MONDAY NIGHT INTO TUESDAY MORNING. MAINTAINED THE MENTION OF ISOLATED THUNDERSTORMS EMBEDDED IN THE MORE WIDESPREAD RAIN SHOWER ACTIVITY BECAUSE BOTH THE GFS AND ECMWF INDICATE THAT WE WILL RECEIVE A GOOD INFLUX OF MID TO UPPER LEVEL MOISTURE AS A WEAK SHORTWAVE TROUGH OVER THE OPEN WATERS OF THE PACIFIC IS DRAWN OVER THE REGION DURING THIS TIME. MOST OF THE RICH/TROPICAL MOISTURE ASSOCIATED WITH THIS FEATURE WILL BE SCOURED OUT BY THE HIGH TERRAIN OF MEXICO...BUT WHAT REMAINS WILL CERTAINLY HELP SUPPORT WIDESPREAD RAIN SHOWERS MONDAY NIGHT AND TUESDAY MORNING. AS OPPOSED TO OUR LAST SYSTEM...MODELS DO NOT FORECAST STEEP MID-LEVEL LAPSE RATES BEFORE PRECIPITATION BEGINS...SO THINK THAT ANY EMBEDDED THUNDERSTORMS ARE VERY UNLIKELY TO PRODUCE SEVERE WEATHER AT THIS TIME. AS THE WEAK PACIFIC OCEAN ENERGY MOVES EAST OF THE REGION...IT WILL BE REPLACED BY A GOOD MID TO UPPER LEVEL DRY SLOT WORKING IN BEHIND OUR NEVADA SHORTWAVE WHICH IS EXPECTED TO MOVE EAST...RIGHT ALONG THE RED RIVER DURING THE DAY ON TUESDAY. THIS DRY SLOT WILL BRING AND END TO PRECIPITATION OVER THE CWA FROM SOUTHWEST TO NORTHEAST TUESDAY AFTERNOON AS THE DRY SLOT WORKS TO DRY OUT THE ATMOSPHERE FROM THE TOP DOWN. DEPENDING ON THE EXACT TRACK OF THE NEVADA SHORTWAVE TROUGH...WE MAY SEE SOME PRECIPITATION LINGER JUST SOUTH OF THE RED RIVER TUESDAY EVENING AS COLDER AIR BUILDS INTO THE REGION FROM THE NORTHWEST. THE CONSENSUS OF 10/12Z GUIDANCE CONTINUES TO INDICATE THAT THE TROUGH WILL MOVE EAST RIGHT ALONG THE RED RIVER WHICH KEEPS ANY CHANCE OF A CHANGE OVER TO SNOW NORTH OF THE RED RIVER AT THIS TIME. EVEN THE ECMWF...WHICH HAS BEEN MOST AGGRESSIVE WITH COLD AIR ADVECTION ON THE BACK SIDE OF THIS TROUGH...KEEPS TEMPERATURES NEAR THE RED RIVER IN THE UPPER 30S WHILE THERE IS STILL ENOUGH MOISTURE IN PLACE FOR PRECIPITATION TO DEVELOP NEAR THE CWA. AS A RESULT...KEPT A SLIGHT CHANCE FOR RAIN/RAIN SHOWERS IN THE FORECAST NEAR THE RED RIVER THROUGH MIDNIGHT/06Z TUESDAY NIGHT. EXTENDED...COLDER AIR WILL BUILD INTO NORTH AND CENTRAL TX BEHIND THE NEVADA SHORTWAVE TROUGH. HOWEVER PERSISTENT NORTHWEST/WESTERLY FLOW WILL ONCE AGAIN SCOUR LOW LEVEL MOISTURE WELL AWAY FROM THE REGION REDUCING THE CHANCE OF ANY PRECIPITATION THROUGH THE REMINDER OF THE WEEK. WE ARE EXPECTED TO REMAIN IN A SOMEWHAT ACTIVE/FAST FLOW REGIME ALOFT WHICH WILL SEND A COUPLE OF WEAK UPPER LEVEL DISTURBANCES OVER THE CWA FOR THE LATTER HALF OF THE UPCOMING WORK WEEK. NONE OF THESE DISTURBANCES IS PARTICULARLY IMPRESSIVE IN NATURE IN TERMS OF ABILITY TO SPREAD LARGE SCALE FORCING FOR ASCENT OVER THE REGION. WE WILL LIKELY SEE SKIES CLOUD UP AS EACH DISTURBANCE PASSES BY...BUT WITHOUT BETTER MOISTURE TO WORK WITH...THINK THAT CHANCE OF ANY PRECIPITATION WILL REMAIN LOW THROUGH THE END OF THE WEEK. THE ECMWF HAD BEEN DRAGGING A STRONG BUT POSITIVELY TILTED TROUGH OVER THE SOUTH PLAINS AT THE END OF THE WEEK. THIS WOULD HAVE SPREAD MORE PERSISTENT LARGE SCALE FORCING FOR ASCENT OVER THE CWA WHICH MAY HAVE RESULTED IN SOME LIGHT PRECIPITATION...AND POSSIBLY EVEN SOME WINTRY WEATHER. HOWEVER TODAYS 12Z ECMWF IS IN MUCH BETTER AGREEMENT WITH THE GFS WHICH KEEPS A LARGE TROUGH OVER THE NORTHEASTERN CONUS...WITH ONLY TRANSIENT/WEAK DISTURBANCES PROVIDING LIFT OVER THE CWA THROUGH NEXT WEEKEND. AS A RESULT MAINTAINED A DRY FORECAST THROUGH NEXT WEEKEND...WITH TEMPERATURES HOLDING NEAR OR MAYBE SLIGHTLY BELOW SEASONAL NORMALS AS EACH UPPER DISTURBANCE SENDS A REINFORCING SHOT OF COOL AIR INTO NORTH AND CENTRAL TX. CAVANAUGH && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 42 60 45 54 38 / 10 10 50 70 10 WACO, TX 44 62 48 63 40 / 10 20 50 50 10 PARIS, TX 39 60 42 46 38 / 5 10 30 70 20 DENTON, TX 40 61 44 49 36 / 5 10 50 70 20 MCKINNEY, TX 40 61 44 49 37 / 5 10 50 70 20 DALLAS, TX 42 60 46 55 39 / 10 10 50 70 10 TERRELL, TX 42 60 45 55 39 / 10 20 40 70 10 CORSICANA, TX 46 58 47 59 41 / 10 20 40 60 10 TEMPLE, TX 47 63 49 65 40 / 10 30 50 50 10 MINERAL WELLS, TX 37 62 44 56 35 / 5 10 60 50 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 58/91
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AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1235 AM EST MON FEB 11 2013 .SYNOPSIS... A WARM FRONT WILL LIFT NORTHEAST ACROSS THE REGION LATER TONIGHT FOLLOWED BY A TRAILING COLD FRONT THAT WILL SWEEP EAST THROUGH THE AREA MONDAY. ANOTHER STORM SYSTEM LOOKS TO MOVE NORTHEAST ACROSS THE EASTERN CAROLINAS ON WEDNESDAY...POSSIBLY RESULTING IN THE NEXT ROUND OF WINTRY WEATHER FOR MIDWEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 930 PM EST SUNDAY... WELL...BAND OF SLEET/SOME SNOW AND RAIN MOVED IN CAUSING SOME MINOR TRAVEL ISSUES. THE DUAL POL HAS DONE AN EXCELLENT JOB OF DEPICTING THIS. CURRENTLY...SOME SLEET STILL BEING OBSERVED OVER THE ROANOKE VALLEY. RADAR INDICATES POCKETS OF SLEET AND GIVEN THE DRY AIRMASS...SHOULD SEE THINGS WET BULB ENOUGH TO BRING SLEET TO THE PIEDMONT BUT NO ACCUMULATION HERE GIVEN WARMER TEMPS. OVER THE ALLEGHANY HIGHLANDS OF BATH INTO PORTIONS OF GREENBRIER COULD SEE A FEW TENTHS OF AN INCH OF SNOW/SLEET. THE LATEST RUC HAD THIS NAILED AS FAR AS HAVING A NARROW BAND OF PRECIP AND DRYING IT OUT TO THE WEST. HAVE SINCE FOLLOWED THIS MODEL UNTIL DAWN...BUT LEFT ROOM IN FOR DEVELOPMENT OF LIGHT PRECIP IN THE WEST...BUT ONLY SLIGHT TO LOW CHANCE. MOST AREAS OVERNIGHT WILL BE DRY. WARM FRONT EDGES NWD...BUT IN-SITU WEDGE WILL HOLD AT LEAST UNTIL MID MORNING MONDAY BEFORE THE COLD FRONT ARRIVES. WILL KEEP IT CLOUDY ALL NIGHT. RUC DOES SHOW SOME HIGHER OMEGA RETURNING OVER THE SOUTHERN CWA OVERNIGHT SO KEPT POPS HIGHER HERE. SO IN SUMMARY CUT POPS BACK FROM EARLIER FORECAST. TEMPS COOL SOME WITH PRECIP BUT THERE IS MORE OF AN INCREASE IN THE DEWPOINTS. THINK TEMPS STAY STEADY IN THE WEDGE OR SLOWLY FALL WHILE STEADY OR SLOWLY RISING TEMPS OCCUR OVER THE FAR SW OUTSIDE THE WEDGE BARRING ANY PRECIP. THE WINDS WILL BE STRONGEST BETWEEN THIS AFD AND ABOUT 08Z...WHEN SFC WINDS TURN MORE SSW. COULD BE A FEW GUST ON THE HIGHER RIDGES LIKE MT ROGERS OVER 50 KNOTS...BUT ISOLATED NATURE AND WILL NOT UPGRADE TO HIGH WIND WARNING. PREVIOUS VALID DISCUSSION... A COLD FRONT WILL SWEEP EAST MONDAY. MOST OF THE RAIN WILL END BY MID MORNING MONDAY. IT SHOULD BE WINDY MONDAY WITH DEEP MIXING TO JUST ABOVE H8 AND A WESTERLY DOWNSLOPING FLOW. WIND SPEEDS WILL BE NEAR ADVISORY CRITERIA LEVELS WITH WIND GUSTS ACROSS NORTHWEST NORTH CAROLINA AND INTO THE NEW RIVER VALLEY. HIGHS MONDAY WILL BE MILD WITH READINGS FROM THE LOWER 50S IN THE NORTHWEST TO THE MID 60S IN THE SOUTHEAST. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... AS OF 345 PM EST SUNDAY... MONDAY NIGHT THROUGH WEDNESDAY NIGHT... MOISTURE BELOW 850 MB IN SOUTHEAST WEST VIRGINIA ALTHOUGH MODELS NOT PRINTING OUT ANY PRECIPITATION. WINDS REMAIN GUSTY UNTIL TUESDAY MORNING. WINDS AND CLOUDS DIMINISH TUESDAY AFTERNOON AS SURFACE HIGH PRESSURE BUILDS INTO THE AREA. HAVE A LIMITED AMOUNT OF SNOW SHOWERS IN WESTERN GREENBRIER COUNTY...BUT CLOUDS WILL HOLD IN LONGER THROUGH THE MORNING IN THE FAVORED UPSLOPE AREAS. NEXT SYSTEM REMAINS COMPLEX. STILL MODEL DIFFERENCES IN TIMING AND EVEN MORE SO IN TEMPERATURE PROFILE. EXPECT BULK OF THE PRECIPITATION BETWEEN 12Z/7AM WEDNESDAY AND 06Z/1AM THURSDAY. TYPE AND AMOUNT OF PRECIPITATION WILL BE A CHALLENGE. NAM BUFKIT WAS SHOWING COLDER TEMPERATURE PROFILES THEN GFS BUFKIT. BEST LOOKING PART OF THE STORM AT THIS POINT IS THE ISENTROPIC LIFT AND UPSLOPE. WILL CONTINUE TO HIGHLIGHT THIS SYSTEM IN THE HAZARDOUS WEATHER OUTLOOK. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 230 PM EST SUNDAY... FROM THURSDAY THROUGH SUNDAY...A LONGWAVE TROUGH IS PROGGED TO BE OVER THE JAMES BAY REGION OF CANADA AND SOUTH INTO THE EASTERN U.S. THAT IS ONE ELEMENT OF THIS PORTION OF THE FORECAST THAT HAS MODERATELY HIGH CONFIDENCE. ANOTHER ELEMENT WITH MODEATELY HIGH CONFIDENCE IS THE TEMPERATURE FORECAST...AT LEAST THE TREND. PROGRESSIVELY COLDER AIR WILL BE ENTERING THE REGION ON GUSTY NORTHWEST WINDS...ESPECIALLY BY THE START OF NEXT WEEKEND. THERE IS LOW CONFIDENCE CONCERNING THE SPEED AND TRACK OF INDIVIDUAL SHORTWAVE TROUGHS WITHIN THE LARGER LONGWAVE TROUGH PATTERN. GUIDANCE COMPARED TO YESTERDAY...AND COMPARED TO EACH OTHER WITH THE LATEST 12Z...7AM...MODELS...OFFER DIFFERENT SOLUTIONS AND EACH WOULD IMPACT THE WEATHER ACROSS OUR REGION IN VARIOUS WAYS. GOING TO LEAN TOWARDS A DRIER...BUT COMPARABLE...SOLUTIION TO THAT OFFERED FOR THIS TIME PERIOD BY HPC. GIVEN THIS...OUR FORECAST WILL REFLECT ONE THAT WILL HAVE PROGRESSIVELY COLDER TEMPERATURES. HIGHS ON THURSDAY WILL BE ROUGHLY 10 TO 15 DEGREE WARMER THAN THOSE EXPECTED ON SUNDAY. LIKEWISE...LOWS ON THURSDAY NIGHT WILL BE ROUGHLY 10 DEGREES MILDER THAN THOSE EXPECTED SATURDAY NIGHT. WE WILL HAVE UPSLOPE RAN/SNOW SHOWERS FORECAST IN SOUTHEAST WEST VIRGINIA AND NEIGHBORING PORTIONS OF SOUTHWEST VIRGINIA THURSDAY NIGHT AND FRIDAY AS A WEAK SHORTWAVE TROUGH MOVES THROUGH OHIO VALLEY. BETTER COVERAGE OF PRECIPITATION IS FORECAST SATURDAY AND SATURDAY NIGHT AHEAD OF..AND DURING THE PASSAGE OF A SLIGHTLY MORE ROBUST SHORTWAVE TROUGH THAT WILL HAVE ITS ORIGINS FROM THE CENTRAL PLAINS...AND GET AMPLYFIED AS IT INTERACTS WITH THE EASTERN LONGWAVE TROUGH. BEHIND THIS SYSTEM...UPSLOPE SNOW SHOWERS ARE EXPECTED OVER SOUTHEAST WEST VIRGINIA DURING THE DAY SUNDAY. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 12120 AM EST MONDAY... INITIAL BATCH OF FAST MOVING PRECIP HAS QUICKLY EXITED TO THE EAST LEAVING SOME LEFTOVER PATCHY -RA/-DZ IN SPOTS MAINLY OVER THE WEST. EXPECT MAY SEE SOME ADDED RAIN FILL BACK IN AHEAD OF THE WARM FRONT BACK OVER TN THROUGH DAYBREAK...OTRW THINKING CIGS WILL LOWER FROM CURRENT MVFR/VFR LEVELS TO IFR MOST SPOTS AS THE WARMER AIR ALOFT WORKS OVERTOP THE LINGERING LOW LEVEL WEDGE. HOWEVER CONFIDENCE RATHER LOW GIVEN MODEL UNCERTAINTY AS DEVELOPMENT OF MORE RAIN TO THE SW COULD ACTUALLY KEEP CIGS HIGHER VS THE LOWER DRIZZLE/STRATUS SCENARIO. LOW LEVEL WIND SHEAR WILL REMAIN A PROBLEM AT MOST LOCATIONS DURING THE OVERNIGHT WITH STRONG SFC WINDS THE MAIN CONCERN AT KBLF WHERE COULD GUST TO 35 KTS OVER THE NEXT FEW HOURS. THE LOW LVL WIND SHEAR STARTS TO GO AWAY BY MID MORNING MONDAY AS THE FRONT MOVES ACROSS AND MIXING TAKES PLACE. THE RAIN/DRIZZLE SHOULD ALSO START TO EXIT LEAVING BEHIND LOWER CIGS IN ITS WAKE WITH UPSLOPE SHOWERS OVER SE WV. THE MIXING SHOULD BRING ABOUT SCATTERING OF LOWER CIGS EAST OF THE WV MTNS BY MIDDAY...WITH GUSTY WEST-NW WINDS AT 20 TO 35 KNOTS POSSIBLE. WILL HAVE BLF CLEARING OUT AS WELL AROUND MIDDAY...GIVEN FAST EXIT OF LOW LVL MOISTURE. EXPECT VFR TO THEN LINGER INTO MONDAY NIGHT AND TUESDAY WITH HIGH PRESSURE SPILLING IN FROM THE WEST BEFORE WEAKENING TUESDAY EVENING. ANOTHER AREA OF LOW PRESSURE IS THEN EXPECTED TO FORM ON THE RESIDUAL FRONT TO THE SOUTH BY MIDWEEK WITH PERHAPS ANOTHER ROUND OF PRECIP AND LOWER CIGS ON WEDNESDAY. VFR SHOULD AGAIN RETURN TO ALL SITES ON THURSDAY AS WEAK HIGH PRESSURE BUILDS IN BEHIND THE EXITING AREA OF LOW PRESSURE. THE ARRIVAL OF MUCH COLDER AIR BY WEEKS END WILL LIKELY PRODUCE A PERIOD OF UPSLOPE MVFR CLDNS FOR THE SE WVA SITES FRIDAY WITH SCATTERED SNOW SHOWERS POSSIBLE OTRW VFR ELSW. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WIND ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR VAZ007-009- 010-015. NC...WIND ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR NCZ001-018. WV...WIND ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR WVZ042. && $$ SYNOPSIS...JH/KK NEAR TERM...KK/WP SHORT TERM...AMS/WP LONG TERM...DS AVIATION...JH/KK/WP
AREA FORECAST DISCUSSION
NWS SPOKANE WA
217 PM PST Mon Feb 11 2013 .SYNOPSIS... Moist westerly flow aloft over the region will bring a prolonged period of occasional light mountain snow and a chance of valley rain to mainly far eastern Washington and North Idaho tonight through Thursday. The remainder of the next week will be seasonably cool with a few minor storm systems bringing light mountain snow and valley rain or snow mainly on Saturday and again by late next Monday. && .DISCUSSION... Tonight through Tuesday: An upper level shortwave trough located at 150W in the Gulf of Alaska will flatten out the ridge of high pressure protruding over the region off the eastern pacific. We are already beginning to see some high cloud cover pushing in over the region as some weak isentropic ascent will continue to develop at mid to low levels through tonight, especially across the eastern half of the forecast area with an emphasis in the ID Panhandle. Isentropic ascent will be weak enough with downsloping off the Cascades a factor that I don`t think we will see much in the way of precipitation if any away from the Cascade crest into the Columbia Basin. Extreme eastern WA and into the Idaho Panhandle where upslope flow will help generate some more lift will be the area to watch out for some light snowfall. Best chances for snow will be late tonight into Wednesday as the atmosphere moistens from the top down. It will take some time before snow begins to fall as it will likely evaporate until the mid level cloud deck lowers enough through the night. We could see some seeder feeder development as ice crystals fall into the stratus cloud cover across the valleys in these areas. This would act to enhance snowfall rates in some areas. However, without much in the way of any upper level dynamics to support the isentropic component to this system, I expect snowfall accumulations to be light overall; but, we could see an inch or two of snowfall over Lookout Pass by Wednesday afternoon with another inch or two possible heading over Stevens Pass. Tuesday night through Wednesday: The shortwave trough over the Gulf of Alaska will swing through on Tuesday night. This will result in some better dynamics with a better chance for more significant snowfall accumulations over the Cascade Crest and over into the ID Panhandle. Snow levels will be rising and accumulating snowfall is expected primarily above 3,000 feet with rain in the valleys. Northwest flow will focus the heaviest snowfall in the mountains across the Central Panhandle and into the Camas Prairie by Wednesday. The atmosphere will not be particularly unstable, so I am not expecting bursts of heavy snowfall accumulations. However, steady light snowfall could produce up to around 4 to 6 inches over a 24 hour window Thursday evening through Wednesday evening above 3,500 feet. This will result in more accumulating snowfall along I-90 over Lookout Pass. Winds will be a little breezy, especially up in the mountains as a surface low develops in the eastern Gulf of Alaska ahead of the upper level wave and traverses across northern BC and northern Alberta. Models are now placing the low a bit further north than in previous runs, so the possibility of stronger winds do not look as likely. The resulting pressure gradient will generate winds out of the southwest, which will draw in some warmer air (hence the rising snow levels). This will also result in temperatures a bit warmer Tuesday night into Wednesday. /SVH Wednesday Night and Thursday: Very little changes in the pattern from the previous periods are expected as a ridge continues to dominate our weather pattern. With the ridge we will continue to see the NW flow come over the top of the ridge and across the region. Continued moisture from Wednesday will bring snowfall to the Cascade Crests and to the mountains of mainly the Central ID Panhandle. Valleys in the Central Panhandle will likely see rain showers or a mix of wet snow and rain. Continued accumulations in the higher elevations could lead to some decent snow totals throughout the beginning and middle part of the week. The main forcing associated with the tail end of this prolonged period of snow showers looks to be topographical which should keep snow to mainly lighter intensities. When dealing with the QPF for these periods the models are in agreement for the western part of the forecast area but are struggling with the Panhandle. GFS currently has a much more significant amount of moisture in the region compared to the drier ECMWF. Due to the inconsistencies of the GFS I went closer to the Euro solution with the lighter amount of QPF as this moist flow starts to exit the region. Towards the end of the period on Thursday models show a drying trend that will put a stop to most of snow in the Panhandle as the ridge slowly moves inland and the moisture stream moves to the east of the forecast area. Temperatures during these periods become difficult as sky conditions play a large role as to what we see for highs and lows. Clearing during the nighttime will allow temps to plummet whereas clearing in the daytime will allow temps to warm to higher values than with cloudy skies. With the ridge in place we could see some clearing making temps a tough call. Based on no major changes in models kept temps similar to previous forecast and will have to continue watching trends in cloud cover to help pin down temps. /Fliehman Thursday night through Monday...A progressive late winter pattern with a couple minor precipitation bearing waves and some dry days is advertised by the latest medium range forecast runs. There is good agreement between the GFS/ECMWF and Canadian models depicting a ridge aloft Thursday night through Friday with no compelling reason to expect anything beyond some late night/early morning valley and basin fog with seasonably cool temperatures. Saturday looks like the most active and potentially stormy day of the extended period with model agreement continuing...and depicting the approach and passage of a fairly strong but quick moving upper level trough. Because of the speed of this transient system...P-type will be dependent on the time of passage...with an early arrival overnight Friday and Saturday morning bringing light snow accumulations to much of the region...but if the arrival is slowed down by 6 or 8 hours to impact the area during the afternoon then mainly mountain snow with valley/basin rain showers are more likely. It is too far out to pin the exact timing down...but confidecne is high that Saturday will feature a weather producing system. On Sunday and into Monday the next short wave ridge is expected with dry and potentially foggy conditions once again...and the next short wave expected to enter the region on or about late Monday. Temperatures in this progressive late winter pattern are likely to remain around seasonal average with no stagnant periods or sustained advective patterns to allow any appreciable warm-ups or cool-downs. /Fugazzi && .AVIATION... 18Z TAFS: The western edge of the stratus is following right along the WA/ID border up to the Spokane/Coeur d`Alene areas and is in much of the northern valleys. This has resulted in many of the TAF sites across the region being right on the edge of much of the stratus. Models are not doing a particularly good job of handling the boundary layer moisture. HRRR model shows much of the stratus burning off this afternoon with it having a harder time redeveloping tonight as mid to high level clouds increase over the region. Other model guidance shows this stratus remaining over the region through tomorrow morning. We went with the idea that the stratus will burn off along its western edge with a FEW-BKN deck btwn 2.5 to 4 kft agl from KLWS up to KGEG and BKN-OVC deck at KCOE. This stratus is expected to fill back in toward the west by this evening, but how much it does may be limited by the higher cloud cover moving in aloft ahead of the next system for late tonight into Tuesday. Confidence in stratus coverage is low due to high model uncertainty. /SVH && .PRELIMINARY POINT TEMPS/POPS... Spokane 28 39 32 41 27 38 / 0 20 10 20 10 0 Coeur d`Alene 30 38 32 41 27 38 / 20 40 30 20 10 10 Pullman 30 44 35 46 29 41 / 0 30 30 50 30 20 Lewiston 33 48 37 52 34 46 / 0 20 10 30 30 20 Colville 29 39 32 43 27 40 / 10 20 10 10 10 0 Sandpoint 31 38 33 40 27 36 / 40 50 60 20 20 10 Kellogg 30 39 33 43 29 40 / 30 60 80 70 30 20 Moses Lake 29 46 35 49 28 43 / 0 0 0 0 0 0 Wenatchee 30 44 34 47 30 44 / 0 0 0 0 0 0 Omak 23 40 26 40 25 37 / 10 0 10 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1008 AM PST Mon Feb 11 2013 .SYNOPSIS... Dry and seasonably cool conditions will prevail through Monday with some patchy fog. The next storm system is expected to arrive on Tuesday bringing light snow mainly to the mountains. The passage of this storm will bring breezy and gusty conditions to the mountains Tuesday night. Mainly dry conditions with seasonal temperatures is expected for the remainder of the week. && .DISCUSSION... Updated the forecast to decrease cloud cover over much of the basin and into the Palouse and Camas Prairie. Satellite imagery this morning is showing much of the stratus banked up in the northern valleys and Panhandle valleys. Light easterly winds downsloping off the mountains into the Palouse and L-C Valley areas has limited the stratus development. Mostly sunny skies are expected through the afternoon hours today. The stratus should burn off a bit from the edges this afternoon with some sun breaks possible late in the afternoon, but mostly cloudy conditions across the northern valleys and into the Panhandle is expected. A weak upper level wave passing across the region with some weak upslope flow into these areas may yield some flurries as well. High clouds will continue to stream over the region ahead of the next wave that is expected to begin to move in tonight with a better chance for some snow, mainly in the Idaho Panhandle and up along the Cascade crest. /SVH && .AVIATION... 18Z TAFS: The western edge of the stratus is following right along the WA/ID border up to the Spokane/Coeur d`Alene areas and is in much of the northern valleys. This has resulted in many of the TAF sites across the region being right on the edge of much of the stratus. Models are not doing a particularly good job of handling the boundary layer moisture. HRRR model shows much of the stratus burning off this afternoon with it having a harder time redeveloping tonight as mid to high level clouds increase over the region. Other model guidance shows this stratus remaining over the region through tomorrow morning. We went with the idea that the stratus will burn off along its western edge with a FEW-BKN deck btwn 2.5 to 4 kft agl from KLWS up to KGEG and BKN-OVC deck at KCOE. This stratus is expected to fill back in toward the west by this evening, but how much it does may be limited by the higher cloud cover moving in aloft ahead of the next system for late tonight into Tuesday. Confidence in stratus coverage is low due to high model uncertainty. /SVH && .PRELIMINARY POINT TEMPS/POPS... Spokane 35 28 39 30 44 26 / 0 0 20 10 20 10 Coeur d`Alene 35 29 38 30 42 26 / 0 10 40 30 20 10 Pullman 38 31 44 34 46 28 / 0 0 30 30 50 20 Lewiston 44 34 48 36 51 33 / 0 0 20 10 30 30 Colville 37 29 39 31 46 26 / 10 10 20 10 10 10 Sandpoint 36 30 38 33 41 26 / 10 20 50 60 20 20 Kellogg 36 29 39 33 42 28 / 10 30 60 70 70 30 Moses Lake 44 29 46 34 48 27 / 0 0 0 0 0 0 Wenatchee 42 30 44 34 47 29 / 0 0 0 0 0 0 Omak 35 24 40 26 42 24 / 0 10 0 10 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1138 PM CST SUN FEB 10 2013 .SHORT TERM...TONIGHT 829 PM CST SUN FEB 10 2013 WIND ADVISORY TO BE ISSUED SHORTLY...SEE DETAILS BELOW. THE CORE OF A LOW PRESSURE SYSTEM IS CURRENTLY JUST TO THE WEST OF THE FORECAST AREA ALONG THE I-35 CORRIDOR IN SOUTH CENTRAL MINNESOTA. EAST OF THIS LOW...A WARM FRONT EXTENDS TO THE WEST INTO WESTERN WISCONSIN WITH WIDESPREAD RAIN AND DRIZZLE OCCURRING ALONG AND TO THE SOUTH OF IT. SOME FOG STILL REMAINS ALONG AND NORTH OF THIS FRONT...BUT VISIBILITY HAS NOT BEEN BELOW A MILE IN THIS REGION...SO WILL BE DROPPING THE FOG FROM THE FORECAST. BASED ON RADAR AND THE LATEST OBSERVATIONS...IT APPEARS THAT THE BACK EDGE OF THE RAIN/DRIZZLE IS RAPIDLY MOVING TO THE NORTHEAST ACROSS NORTHEAST IOWA. EXPECT THAT AS THIS BACK EDGE MOVES THROUGH THAT THERE WILL BE A PERIOD OF DRY CONDITIONS THIS EVENING AND OVERNIGHT. FURTHER TO THE WEST...MAINLY ALONG AND SOUTH OF THE SURFACE LOW...PRECIPITATION HAS CHANGED OVER TO SNOW ALONG THE I-35 CORRIDOR WHERE 11.00Z RAP/LAPS SOUNDINGS INDICATE THAT THE THERMAL PROFILE HAS COOLED TO ALL BEING BELOW FREEZING. DODGE COUNTY AND PORTIONS OF SOUTHEAST MINNESOTA MAY GET CLIPPED BY SOME OF THIS SNOW...BUT IT APPEARS TO MAINLY BE PROPAGATING TO THE NORTHEAST AND SHOULD NOT DROP MUCH ACROSS THIS REGION. AS THE LOW MOVES OFF TO THE NORTHEAST...THE COLD FRONT THAT CURRENTLY EXTENDS TO THE SOUTHEAST OF IT INTO WESTERN IOWA WILL SWING THROUGH THE REGION AROUND AND SHORTLY AFTER MIDNIGHT. SNOW SHOWERS WILL MOVE IN AFTER THE FRONT PASSES THOUGH THEY WILL NOT BE VERY INTENSE. VISIBILITIES HAVE MAINLY BEEN IN THE 1-3SM RANGE AND THAT IS EXPECTED TO BE THE LOW END OF WHAT WE WILL SEE AS IT MOVES INTO THE REGION OVERNIGHT INTO TOMORROW. THE TIGHTENING SURFACE PRESSURE GRADIENT WILL ALSO TRACK TO THE NORTHEAST WITH THE LOW MOVING IN THAT DIRECTION. THE CORE OF THESE STRONG WINDS WILL EXTEND ACROSS SOUTHEAST MINNESOTA...NORTHEAST IOWA AND SOUTHWEST WISCONSIN...PARTICULARLY IN THE HIGHER ELEVATIONS. 11.00Z AND PREVIOUS RAP BUFKIT SOUNDINGS SHOW THAT WIND GUSTS SHOULD BE AROUND 45 MPH AT TIMES...PARTICULARLY TOMORROW MORNING AFTER SUNRISE. WILL BE ISSUING A WIND ADVISORY STARTING AT MIDNIGHT AND RUNNING IT INTO 3PM TOMORROW AFTERNOON WHEN IT APPEARS THAT THE WINDS WILL WEAKEN ALONG WITH THE PRESSURE GRADIENT. THE LOBE OF STRONGEST WINDS WILL START OUT IN THE SOUTH AND WORK THEIR WAY NORTHWARD AFTER MIDNIGHT...SO SOME LOCATIONS IN THE ADVISORY MAY BE A LITTLE DELAYED IN GETTING THE STRONGEST WINDS COMPARED TO THAT AREA. .LONG TERM...WEDNESDAY THROUGH SUNDAY 256 PM CST SUN FEB 10 2013 NORTHWEST FLOW ALOFT WILL SET UP OVER THE UPPER MIDWEST IN THE WAKE OF THE CURRENT STORM SYSTEM. THIS WILL ALLOW A SYSTEM TO DROP INTO THE REGION FOR THE MIDDLE OR END OF THE WEEK. THE MODELS SHOW VERY LITTLE CONSISTENCY ON THE TIMING OF THIS FEATURE. THE 10.12Z GFS IS THE FASTEST BRINGING IN WEDNESDAY AFTERNOON WHILE THE 10.12Z GEM IS THE SLOWEST AND STRONGEST AND DOES NOT BRING IT IN UNTIL THURSDAY NIGHT. UNTIL THESE TIMING DIFFERENCES ARE WORKED OUT...WILL NEED TO CARRY A MENTION OF PRECIPITATION FROM WEDNESDAY NIGHT THROUGH FRIDAY WITH THE BEST CHANCES CENTERED ON WEDNESDAY NIGHT AND THURSDAY. THE SURFACE LOW MAY PASS BY JUST TO THE NORTH OF THE AREA THURSDAY BRINGING ENOUGH WARM AIR FOR A MIX OF RAIN AND SNOW ACROSS THE SOUTH WITH LIGHT SNOW EXPECTED ELSEWHERE. && .AVIATION...THROUGH 06Z TUESDAY 1138 PM CST SUN FEB 10 2013 PRECIPITATION IS CHANGING OVER TO SNOW AS A COLD FRONT APPROACHES THE REGION. CONDITIONS ARE EXPECTED TO BE MAINLY AT IFR OR LOWER THROUGHOUT THE REGION THOUGH LSE HAS BEEN AT LOW END MVFR WITH A 1100FT CEILING. CEILINGS WILL LIKELY BE MORE STABLE THAN WHAT VISIBILITIES ARE AS THE SNOW IS FAIRLY VARIABLE WITH CONDITIONS RANGING FROM 6SM DOWN TO 1 1/2SM AT TIMES AS THE SNOW SHOWERS COMES THROUGH. EXPECT THAT THIS WILL BE THE CASE THROUGH MUCH OF THE MORNING AND EARLY AFTERNOON HOURS BEFORE THE FORCING WEAKENS LATE IN THE AFTERNOON. WINDS WILL INCREASE AS THE COLD FRONT MOVES THROUGH THE REGION TONIGHT WITH SUSTAINED WINDS AROUND 20 TO 25KTS WITH GUSTS UP TO 35-37KTS AT TIMES. THESE WEST TO NORTHWEST WINDS WILL DIMINISH IN SPEED LATE IN THE AFTERNOON AND EVENING HOURS AS THE SURFACE LOW ASSOCIATED WITH THIS SYSTEM TRACKS FURTHER TO THE NORTHEAST. && .ARX WATCHES/WARNINGS/ADVISORIES... 829 PM CST SUN FEB 10 2013 WI...WIND ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM CST MONDAY FOR WIZ032>034-041>044-053>055-061. MN...WIND ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM CST MONDAY FOR MNZ079-086>088-094>096. IA...WIND ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM CST MONDAY FOR IAZ008>011-018-019-029-030. && $$ SHORT TERM...HALBACH LONG TERM...04 AVIATION...HALBACH
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1030 PM CST SUN FEB 10 2013 .UPDATE... ISSUED A WIND ADVISORY FOR THE ENTIRE CWA FOR OVERNIGHT INTO MONDAY. POINTS AGAINST ISSUING WITH AN 06Z START TIME ARE: THE INVERSION OVER THE SNOW-PACK PREVENTING FULL MOMENTUM TRANSFER TO THE SURFACE TONIGHT. USUAL DIFFICULTY IN GETTING SUSTAINED 30 MPH WINDS WITH THE ROUGH TERRAIN...TREES...HILLS...ETC. POINTS FOR ARE THE 40 TO 44 KNOT WINDS JUST OFF THE SURFACE ABOVE A WEAK NEAR-SURFACE INVERSION. ONCE COLD AIR ADVECTION BEGINS WITH 4 TO 6 MB PER 3 HOUR SURFACE PRESSURE RISES...THIS INVERSION DISAPPEARS AND THERE IS A GOOD POTENTIAL OF A 40 KNOT GUST TO REACH THE SURFACE. 36KT GUST AT MONROE REPORTED AT 0335Z SHOWS HOW EASILY AN ADVISORY LEVEL GUST COULD REACH THE SURFACE. REALIZE IT WILL BE MARGINAL OVER THE NORTHEAST AS GRADIENT WONT BE AS TIGHT UNTIL LATER IN THE OVERNIGHT...BUT NEW NAM FORECAST SOUNDINGS FOR SHEBOYGAN IN LINE WITH RAP SHOWING MIXING UP TO 40-41 KTS BY 08Z...SO AN ISOLATED ADVISORY LEVEL GUST NOT OUT OF THE QUESTION. BETTER CHANCE FOR WIDESPREAD ADVISORY CONDITIONS MONDAY...WITH MIXING UP TO 875 MB AND WEST TO NORTHWEST WINDS AROUND 40 KTS. && .AVIATION/06Z TAFS/... WILL TAKE OUT LOW-LEVEL WIND SHEAR AS DIFFERENTIAL DECREASES WITH INCREASING SURFACE WIND GUSTS. VFR CONDITIONS OVER THE FORECAST AREA ARE TEMPORARY AND WILL DROP BACK TO MVFR BY ISSUANCE TIME. WIND GUSTS WILL BE THE MAIN ISSUE AS SOUTHWEST WINDS WILL INCREASE TO 20 TO 25 KT SUSTAINED...WITH GUSTS OF 30 TO 40 KTS...BECOMING WEST IN THE MORNING WITH GUSTS TO 45 KNOTS BY LATE IN THE MORNING INTO THE AFTERNOON. WINDS WILL SLOWLY DECREASE FROM SOUTHWEST TO NORTHEAST DURING THE AFTERNOON AND EVENING...BUT ENOUGH GRADIENT FOR GUSTS TO AT LEAST 20 KNOTS AT KMSN AND KUES THROUGH 06Z TUESDAY...AND AROUND 25 KNOTS AT KENW AND KMKE. WILL SEE LAST BAND OF LIQUID PCPN PUSH OUT OVER LAKE MICHIGAN AROUND/SHORTLY AFTER 06Z...WITH POCKETS OF LIGHT SNOW SHOWERS OR FLURRIES ROTATING THROUGH THE FORECAST AREA OVERNIGHT AND MONDAY WITH VORTICITY MAXIMA SPINNING AROUND CLOSED 500 MB LOW. WILL KEEP MVFR CIGS THROUGH THE REMAINDER OF THE FORECAST...THOUGH SOME IFR POSSIBLE IN THE SNOW SHOWERS. && .MARINE... ADJUSTED START TIME OF GALE WARNING TO 06Z...THOUGH FREQUENT GALE GUSTS BECOME MORE LIKELY CLOSER TO 08Z...THE POTENTIAL FOR GALE GUSTS WITH THE EARLY WIND GUST TO 35 KNOTS AT MONROE AND COLLABORATION SUPPORTED THE 06Z START. WILL NEED A SMALL CRAFT ADVISORY AFTER GALE WARNING EXPIRES...THOUGH LATEST DATA SUGGESTS GALE WARNING MAY NEED AND EXTENSION OVER THE THE NORTHERN ZONES. WAVES WILL BEGIN TO SUBSIDE MONDAY MORNING WITH REDUCED FETCH AS WINDS TURN WEST. && .PREV DISCUSSION... /ISSUED 340 PM CST SUN FEB 10 2013/ VERY SHORT TERM...TONIGHT AND MONDAY. RAIN WILL WIND DOWN THROUGH LATE AFTERNOON. COULD SEE A QUICK ROUND OF SHOWERS SLIDE THROUGH EARLY EVENING WITH SHORTWAVE. OTHERWISE...WILL SEE SOME DRIZZLE AND FOG AT TIMES THROUGH LATE EVENING. COLD FRONT WILL HEAD THROUGH THE FORECAST AREA LATE EVENING INTO TONIGHT...WITH SNOW SHOWERS LIKELY DEVELOPING BEHIND THE FRONT. BEST CHANCE FOR SNOW SHOWERS LOOKS TO BE LATE TONIGHT THROUGH TOMORROW MORNING AS MAIN SHORTWAVE PUSHES THROUGH. EXPECTING MOST EVERYWHERE SHOULD SEE SHOW SHOWERS...WITH A DUSTING TO A COUPLE TENTHS OF AN INCH POSSIBLE...THE HIGHEST AMOUNTS ACROSS THE NORTHERN FORECAST AREA. SNOW SHOWERS WILL LIKELY WIND DOWN TOMORROW AFTERNOON. OTHER THING OF NOTE WILL BE INCREASING WINDS BEHIND THE COLD FRONT LATE TONIGHT INTO MONDAY. GUSTS OF 35 TO 40 MPH EXPECTED MOST PLACES FROM MID MORNING MONDAY THROUGH MUCH OF THE DAYTIME HOURS. HIGHEST GUSTS WILL BE IN THE SOUTHEAST WHERE THEY COULD APPROACH WIND ADVISORY LEVELS OF 45 MPH. SHORT TERM...MONDAY NIGHT THROUGH WEDNESDAY. UPPER LOW PULLS AWAY FROM THE WESTERN GREAT LAKES A BIT FASTER LATER MONDAY AND MONDAY NIGHT AS MID LEVELS RAPIDLY DRY. HENCE WL LOWER POPS BUT STILL MAY BE ABLE TO SQUEEZE OUT SOME EVENING FLURRIES FROM LINGERING LOW LEVEL RH AND CYCLONIC CURVATURE. OTHERWISE A DRY PERIOD CAN BE EXPECTED AS SOUTHERN WISCONSIN REMAINS IN DRIER WEST-NORTHWEST FLOW WITH PASSING WEAK HIGH PRESSURE ON TUESDAY AND WEDNESDAY. SPLIT CONTINUES THROUGH THIS PERIOD WITH SOUTHERN STREAM REMAINING ACTIVE OVER SOUTHERN CONUS. VERY WEAK RIPPLES CAUGHT IN THE FAST FLOW MAY BRING SEVERAL PERIODS OF CLOUDS TO THE AREA ON TUE AND WED. HOWEVER TEMPERATURES SHOULD AVERAGE CLOSE TO SEASONAL NORMAL. LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY. INCREASINGLY HIGHER AMPLITUDE UPSTREAM RIDGE OVER THE EASTERN PACIFIC RESULTS IN DEEPING LONG WAVE TROFING DOWNSTREAM OVER CENTRAL/EASTERN CONUS EARLY IN THE PERIOD. MEDIUM RANGE GUIDANCE GETTING INTO BETTER AGREEMENT ON CLIPPER-TYPE SYSTEM MOVING SOUTHEAST ALONG THE LEADING EDGE OF THE SURGE OF COLDER AIR AND AFFECTING SOUTHERN WI PERHAPS AS EARLY AS WEDNESDAY NIGHT. HENCE CONFIDENCE INCREASING ON A PERIOD OF -SN AFFECTING SOUTHERN WI AROUND THURSDAY WITH ACCUMULATIONS. CIPS 24 HOUR ANALOGS CENTERED AT 00Z/15 HAS A LOW PROBABILITY OF SNOWFALL EXCEEDING 2 INCHES AT THIS TIME. CONSIDERING THIS WAVE IS TRAVELING ALONG A TIGHTENING BAROCLINIC ZONE...WOULD NOT BE SURPRISED IF FUTURE GUIDANCE SHOWS FURTHER STRENGTHENING OF THIS SYSTEM. WILL TREND UPWARD IN POPS FOR THU AND SURROUNDING PERIODS. ENSEMBLE MEMBERS COMING INTO BETTER AGREEMENT AS WELL ON DEEPENING SHORT WAVE TROUGH OVER WESTERN GTLAKES ON THU. COLDER AIR THEN EXPECTED TO SETTLE OVER THE REGION ON FRIDAY AND LINGER THROUGH THE WEEKEND. BOTH UKMO AND ECMWF INDICATING ANOTHER CLIPPER SYSTEM SLIDING SOUTHEAST ACROSS THE UPPER MIDWEST AND POSSIBLY AFFECTING PORTIONS OF WI OVER THE WEEKEND. HOWEVER CONFIDENCE IN THIS LAST SYSTEM REMAINS LOW. AVIATION /00Z TAFS/... RAIN WILL WIND DOWN THROUGH LATE AFTERNOON. COULD SEE A QUICK ROUND OF SHOWERS SLIDE THROUGH EARLY EVENING WITH SHORTWAVE. OTHERWISE...WILL SEE SOME DRIZZLE AND FOG AT TIMES THROUGH LATE EVENING. CIGS AND VSBYS WILL STAY ON THE LOW SIDE THROUGH THE EVENING AHEAD OF AN APPROACHING COLD FRONT. THE COLD FRONT WILL HEAD THROUGH THE FORECAST AREA LATE EVENING INTO TONIGHT...WITH SNOW SHOWERS LIKELY DEVELOPING BEHIND THE FRONT. BEST CHANCE FOR SNOW SHOWERS LOOKS TO BE LATE TONIGHT THROUGH TOMORROW MORNING AS MAIN SHORTWAVE PUSHES THROUGH. EXPECTING MOST EVERYWHERE SHOULD SEE SHOW SHOWERS...WITH A DUSTING TO A COUPLE TENTHS OF AN INCH POSSIBLE...THE HIGHEST AMOUNTS ACROSS THE NORTHERN FORECAST AREA. SNOW SHOWERS WILL LIKELY WIND DOWN TOMORROW AFTERNOON. VSBYS WILL IMPROVE OVERALL AS THE COLDER AIR FILTERS IN...THOUGH TEMPORARY LOWER VSBYS POSSIBLE IN ANY SNOW SHOWERS. CIGS WILL IMPROVE ALSO...THOUGH LIKELY REMAINING MVFR THROUGH THE DAY MONDAY. MARINE... UPGRADED THE GALE WATCH TO A WARNING...STARTING IT VERY LATE TONIGHT AND RUNNING THROUGH THE DAY MONDAY. SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL THE GALE WARNING GOES INTO EFFECT. LOOKS LIKE A GOOD SHOT FOR GUSTS OF 35 KNOTS DURING THE WARNING PERIOD...POSSIBLY AS HIGH AS 40 KNOTS. WAVES WILL STAY HIGH INTO TONIGHT...SLOWLY SUBSIDING LATE TONIGHT AND MONDAY AS WINDS BECOME OFFSHORE. MAY NEED A SMALL CRAFT ADVISORY FOR AT LEAST MONDAY EVENING AFTER THE GALE ENDS...AS WINDS WILL SLOWLY EASE THROUGH THE EVENING AND OVERNIGHT. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...WIND ADVISORY UNTIL 3 PM CST MONDAY FOR WIZ046-047-051-052- 056>060-062>072. LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR LMZ643>646. GALE WARNING UNTIL 6 PM CST MONDAY FOR LMZ643>646. && $$ UPDATE...REM TONIGHT/MONDAY AND AVIATION/MARINE...DDV MONDAY NIGHT THROUGH SUNDAY...MBK
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
430 AM EST WED FEB 13 2013 .SYNOPSIS... 09Z WATER VAPOR AND H4 RAP ANALYSIS SHOWING AN UPPER LEVEL PATTERN CONSISTING OF BROAD RIDGING ALONG THE PACIFIC COAST FOLLOWED DOWNSTREAM BY BROAD LONGWAVE TROUGHING ACROSS THE CENTRAL PORTION OF THE COUNTRY. A STRONGER IMPULSE/SHORTWAVE IS EMBEDDED WITHIN THIS TROUGH OVER THE CENTRAL/SOUTHERN PLAINS AND IS NOW QUICKLY EJECTING EASTWARD TOWARD THE TN VALLEY AND SOUTHEASTERN STATES. OUR LOCAL AREA RESIDES WITHIN A ZONES OF DEEP SOUTHWEST TO NORTHEAST MOISTURE TRANSPORT BETWEEN THIS LONGWAVE TROUGH...AND A BROAD RIDGE OVER THE WESTERN CARIBBEAN/FL STRAITS. AT THE SURFACE...FL PENINSULA RESIDES WITH THE WARM SECTOR BETWEEN A SYNOPTIC LOW OVER SOUTHERN AL...AND A SURFACE RIDGE ACROSS THE FL STRAITS. SURFACE WARM FRONT EXTENDS EASTWARD FROM THE LOW ACROSS SOUTHERN GA EARLY THIS MORNING WITH A TRAILING COLD FRONT MOVING EASTWARD ACROSS THE CENTRAL GULF OF MEXICO. THIS FRONT WILL ARRIVE OVER OUR REGION LATER TODAY AND TONIGHT. SEEING QUITE A BIT OF LOW CLOUDS AND PATCHY FOG THIS MORNING WITHIN THE DEEP SOUTHERLY MOISTURE TRANSPORT. THE BIGGEST CONCENTRATION OF THESE LOWER CLOUDS IS COMING OFF THE GULF AS THE HIGHER DEWPOINT AIR INTERACTS WITH THE COOLER SHELF WATERS...ESPECIALLY FROM WEST OF TAMPA BAY UP ALONG THE NATURE COAST. DIFFICULT TO DETERMINE IF WE ARE DEALING WITH LOWER STRATUS OR FOG OUT OF THE MARINE AREA...AS WE HAVE NOT SEEN MUCH VISIBILITY REDUCTIONS AT ANY OF THE COASTAL STATIONS. IF VERIFICATION ARRIVES THAT VISIBILITIES ARE SIGNIFICANTLY REDUCED OVER THE MARINE AREA...THEN A DENSE FOG ADVISORY MAY BECOME NECESSARY LATER THIS MORNING. REGIONAL RADARS SHOWS SHOWERS AND STORM ONGOING ACROSS THE FL PANHANDLE/WESTERN BIG BEND WITHIN A BROAD SWATH OF LOW LEVEL MOISTURE TRANSPORT/THETA-E ADVECTION. && .SHORT TERM (TODAY THROUGH FRIDAY)... TODAY/TONIGHT... STRONG MID-LEVEL SHORTWAVE AND ASSOCIATED SURFACE LOW WILL PASS TO OUR NORTH THROUGH THIS EVENING WHILE A COLD FRONT TRAILING SOUTH FROM THE LOW APPROACHES FROM THE EASTERN GULF OF MEXICO. BROAD SYNOPTIC FORCING ASSOCIATED WITH THE PASSING ENERGY ALONG WITH THE LOW LEVEL FORCING AHEAD OF THE FRONT WILL BE ENOUGH TO SUPPORT A BAND OF SHOWERS AND STORMS. THIS BAND IS FORECAST TO SHIFT SOUTH AND SOUTHEAST WITH TIME FROM THE NATURE COAST LATER THIS MORNING AND AFTERNOON....THROUGH THE TAMPA BAY/I-4 CORRIDOR DURING THE AFTERNOON AND EARLY EVENING...AND THEN FURTHER SOUTH LATE IN THE DAY/EVENING. LOW LEVEL WAA REGION/THETA-E ADVECTION AHEAD OF THE FRONT LOOKS TO SLOWLY DIMINISH THROUGH THE DAY...ALONG WITH AN EVENTUAL WEAKENING OF THE OVERALL KINEMATICS. WITH ALL THIS IN MIND...THE MOST ORGANIZED BAND OF CONVECTION SHOULD OCCUR AS THE ACTIVITY IS CROSSING THE NORTHERN AND CENTRAL PORTION OF THE FORECAST AREA...WITH WEAKER AND MORE BROKEN CONVECTION ACROSS THE SOUTH. POPS WILL FOLLOW TODAY WITH LIKELY TO CATEGORICAL VALUES NORTH AND THEN DECREASING TO CHANCE/SLIGHT CHANCE POPS SOUTH AND SOUTHEAST FROM TAMPA BAY. WILL CONTINUE TO MONITOR THE CHANCE OF A FEW STRONGER STORMS...ACROSS THE NATURE COAST THROUGH THE EARLY AFTERNOON WITH ISOLATED STRONG WIND GUSTS THE MAIN THREAT WITH ANY OF THE MORE VIGOROUS CELLS. DEPARTING LOW LEVEL JET SHOULD FURTHER DECREASE ANY WIND THREAT BY LATER IN THE DAY. A SLOW COOL DOWN BEGIN OVERNIGHT AS WINDS SHIFT TO THE NORTH BEHIND THE FRONT. BROAD RESIDUAL SYNOPTIC FLOW AND PLENTY OF LEFTOVER COLUMN MOISTURE MAY STILL SQUEEZE OUT A FEW SHOWERS...BUT COVERAGE AND INTENSITY WILL BE LOW. THURSDAY THROUGH FRIDAY... LOWER CONFIDENCE FORECAST THAN NORMAL FOR THE SHORT TERM PERIOD WHEN IT COMES TO THE DETAILS FOR THE FINAL TWO DAYS OF THE WORK WEEK. THE REGION WILL BE LEFT WITHIN A BROAD CYCLONIC FLOW THAT WILL FEATURE OCCASIONAL WEAKER IMPULSES PASSING THROUGH. THE COMBINATION OF THE PERIODIC SYNOPTIC SUPPORT ASSOCIATED WITH THESE IMPULSES AND SEVERAL FAVORABLE UPPER JET PLACEMENTS WILL FAVOR OFF AND ON PERIOD OF COOL SHOWERS/RAIN. CERTAINLY NOT LOOKING FOR RAIN ALL THE TIME...BUT WHEN THE INGREDIENTS COME TOGETHER WE CAN EXPECT SEVERAL SURGES OF SHOWERS TO CROSS THE PENINSULA. IT IS THE EXACTLY WHERE AND WHEN THAT MAKE THIS FORECAST DIFFICULT. VARYING SOLUTIONS ARE POSED BY THE VARIOUS GUIDANCE MEMBERS...ALL SHOWING THIS OFF AND ON ACTIVITY...BUT WITH UNIQUE PATTERNS. OVERALL IT IS THE I-4 CORRIDOR AND SOUTHWARD THE WOULD SEEM TO BE IN LINE TO EXPERIENCE THE MOST SHOWER ACTIVITY...BUT WILL KEEP CHANCE POPS GOING FURTHER NORTH TO ACCOUNT FOR THE FORECAST UNCERTAINTY. TEMPERATURES WILL BE COOLER THAN PREVIOUS DAYS...ESPECIALLY WHERE THE RAIN PATTERNS EVENTUALLY SET UP. DRIER AIR FILTERING IN FROM THE NORTH IN THE LOWER LEVELS WOULD COMBINE WITH THE RAIN TO PRODUCE POTENTIAL WET-BULB EFFECT. HAVE GONE WITH A BLEND OF THE WARMER MAV AND COOLER MET TEMPERATURES TO BEGIN THE TREND TOWARD POTENTIALLY COOLER END OF THE WEEK TEMPS. && .LONG TERM (FRIDAY NIGHT THROUGH NEXT TUESDAY)... ALL MODELS SHOW A DEEPENING UPPER-LEVEL TROUGH SWINGING THROUGH THE REGION OVER THE WEEKEND. THE GFS AND CANADIAN MODELS SHOW A MORE PROGRESSIVE NATURE TO THE TROUGH WITH THE AXIS MOVING ACROSS THE STATE SATURDAY NIGHT. THE ECMWF IS LAGGING BEHIND BY 12 TO 18 HOURS. IN GENERAL...MODELS ARE FASTER NOW WITH THE TROUGH AND COLD AIR MASS WHICH IN TURN MEANS THE COLD AIR WILL MOVE OUT NEARLY AS FAST AS IT COMES IN. LINGERING SHOWERS OVER OUR SOUTHERN ZONES FRIDAY NIGHT SHOULD COME TO AN END BY SATURDAY MORNING FOLLOWED BY MUCH COOLER AIR AND INCREASING NORTHWESTERLY WINDS. GENERALLY FOLLOWED LATEST MEX GUIDANCE WHICH SHOWS TEMPERATURES HOLDING IN THE MIDDLE 60S EXCEPT FOR OUR FAR SOUTHERN ZONES WHERE WE COULD STILL SEE SOME LOWER 70S. WITH THE COLD AIR MASS COMING IN FASTER...IT NOW LOOKS LIKE OUR COLDEST NIGHT WILL BE SATURDAY NIGHT...ALTHOUGH SUNDAY NIGHT COULD STILL BE QUITE CHILLY. THE FASTER SOLUTION MEANS THE COLD HIGH CENTER MOVES OUT INTO THE ATLANTIC MORE QUICKLY RESULTING IN A RETURN FLOW FROM THE EAST. IT STILL LOOKS LIKE WE WILL SEE FREEZING TEMPERATURES NORTH OF TAMPA BAY...BUT ON SUNDAY MORNING RATHER THAN MONDAY MORNING. SUNDAY SHOULD BE SUNNY AND COOL WITH WINDS SLOWLY DIMINISHING. HIGHS WILL STAY IN THE 60S. SUNDAY NIGHT WILL BE COLD AGAIN...BUT DO NOT EXPECT WIDESPREAD FREEZING TEMPERATURES ANYWHERE. THE COLD HIGH WILL MOVE INTO THE ATLANTIC BY MONDAY PROVIDING A RATHER QUICK WARMUP DURING THE DAY. HIGHS WILL BE ABOUT 8 DEGREES WARMER THAN ON SUNDAY. BY TUESDAY...WE ARE BACK INTO THE MIDDLE 70S TO NEAR 80...BUT A COLD FRONT WILL BE APPROACHING FROM THE NORTHWEST SO THERE WILL BE A SLIGHT CHANCE OF SHOWERS NORTH OF TAMPA. THE FRONT ON TUESDAY LOOKS LIKE ANOTHER MESSY ONE WITH RAIN CHANCES EXTENDING INTO THE MIDDLE OF THE WEEK. && .MARINE... CAUTIONARY LEVEL WINDS OUT OF THE SOUTH WILL CONTINUE TODAY AHEAD OF AN APPROACHING COLD FRONT. AREAS OF MARINE FOG WILL ALSO CONTINUE ACROSS AREAS MAINLY OFFSHORE AND TO THE NORTH OF TAMPA BAY. THE COLD FRONT WILL CROSS THE FORECAST WATERS THIS AFTERNOON AND THIS EVENING WITH A WIND SHIFT TO THE NORTH IN ITS WAKE. WINDS WILL REMAIN FROM A NORTHERLY DIRECTION THROUGH AT LEAST THE EARLY PORTION OF THE UPCOMING WEEKEND AS HIGH PRESSURE SLOWLY BUILDS EAST TOWARD THE REGION. && .AVIATION... AREAS OF LOW CLOUDS AND SOME FOG CONTINUE TO PLAGUE MOST OF THE TAF SITES THIS MORNING. THERE ARE GAPS IN THE COVERAGE WHICH LEADS TO PERIODS OF VFR CONDITIONS BETWEEN THE IFR TO EVEN LIFR CEILINGS. VERY LOW CONFIDENCE IN THE FORECASTS FOR THE NEXT 24 HOURS...BUT IN GENERAL LOOK FOR IMPROVING CONDITIONS BY LATE MORNING WITH MAINLY MVFR CEILINGS. SOME SHOWERS AND STORMS WILL PRECEDE A FRONT LATER THIS AFTERNOON. && .FIRE WEATHER... RELATIVE HUMIDITY VALUES WILL REMAIN WELL ABOVE CRITICAL LEVELS TODAY AHEAD OF A COLD FRONT...HOWEVER GUSTY SOUTHWEST WINDS AND GOOD DISPERSION INDICES CAN BE EXPECTED. SOME LOW LEVEL DRY AIR WILL ATTEMPT TO FILTER IN FROM THE NORTH THE NEXT COUPLE OF DAYS BEHIND THE FRONT...BUT THE PATTERN WILL SUPPORT A CONTINUED CHANCE OF SHOWERS...AN NO CRITICAL LEVELS OF RELATIVE HUMIDITY ARE ANTICIPATED THROUGH FRIDAY. UNLIKE TODAY...DISPERSION INDICES WILL BE QUITE LOW FOR THURSDAY AND FRIDAY...LIKELY REMAINING BELOW 30 FOR MOST LOCATIONS. && .PRELIMINARY POINT TEMPS/POPS... TPA 80 60 71 55 / 60 40 30 60 FMY 85 64 80 60 / 20 30 60 60 GIF 83 57 74 52 / 50 40 30 60 SRQ 78 59 73 58 / 50 40 40 60 BKV 80 54 71 48 / 70 30 20 60 SPG 80 61 71 58 / 60 40 30 60 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...BEACH HAZARDS STATEMENT THROUGH THURSDAY EVENING FOR CHARLOTTE-LEE. LAKE WIND ADVISORY FROM 10 AM THIS MORNING TO 6 PM EST THIS EVENING FOR CHARLOTTE-CITRUS-DESOTO-HARDEE- HERNANDO-HIGHLANDS-HILLSBOROUGH-LEE-LEVY-MANATEE- PASCO-PINELLAS-POLK-SARASOTA-SUMTER. BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR SARASOTA. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
153 AM EST WED FEB 13 2013 .SYNOPSIS... A WARM FRONT WILL LIFT NORTH THROUGH THE REGION THIS MORNING AS LOW PRESSURE PASSES TO THE WEST. A COLD FRONT WILL SWEEP THROUGH THE AREA LATE TODAY...WITH HIGH PRESSURE EXPECTED TO BUILD ACROSS THE REGION THURSDAY INTO EARLY SATURDAY. ANOTHER COLD FRONT WILL PUSH THROUGH THE AREA SATURDAY...FOLLOWED BY STRONGER HIGH PRESSURE AND COOLER CONDITIONS INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... EARLY WEDNESDAY MORNING SURFACE ANALYSIS REMAINED COMPLEX AS THE WARM FRONT HAD ADVANCED TO AROUND ALTAMAHA SOUND...AHEAD OF A SURFACE LOW CENTERED BETWEEN AMG AND JES. THIS LOW AND ASSOCIATED WIDESPREAD PRECIPITATION CONTINUED TO DELAY THE NORTHWARD PROGRESS OF THE WARM FRONT ACROSS SOUTHERN GEORGIA. NORTH OF THE WARM FRONT... WIDESPREAD RAINS OCCASIONALLY PUNCTUATED BY ELEVATED THUNDERSTORMS CONTINUED WITHIN BREAD SWATH OF DEEP LAYER ASCENT/MOISTURE FLOWING ACROSS THE REGION FROM S/SW TO E/NE. MODELS DOING A REASONABLE JOB WITH RAIN DEPICTION BUT MAY STRUGGLE OVERNIGHT WITH THE DETAIL OF THE WARM FRONTAL PROGRESSION GIVEN THE PRESENCE OF THE SURFACE LOW OVER SE GA AND COMPLICATED SURFACE LAYERED STABILITY PROFILES. TEMPS WERE IN THE MID 50S MOST AREAS AS NEAR SATURATION EVIDENT ON SOUNDING PROFILES. OVERNIGHT...A FAIRLY UNSTABLE MID LEVEL ENVIRONMENT WILL SPREAD OVER THE FORECAST REGION BUT GIVEN THE CURRENT RADAR TRENDS AND A MORE BELIEVABLE RUC FORECAST...THE POTENTIAL FOR SEVERE WEATHER OVERNIGHT DOES NOT APPEAR TOO IMPRESSIVE DESPITE INCREASING SHEAR PROFILES. EVEN ACROSS FAR SOUTHERN COUNTIES/CLOSER TO THE WARM FRONT WHERE THUNDERSTORMS WILL REMAIN MOST COMMON...THE POTENTIAL FOR ISOLATED SEVERE WEATHER WILL BE SOMEWHAT GREATER BUT STILL LIMITED DUE TO IMPACTS OF ONGOING/WIDESPREAD PRECIP ON SURFACE BASED INSTABILITY. CATEGORICAL POPS REMAIN IN ORDER OVERNIGHT. FORECASTS CONTINUE TO INDICATE ONLY SLOWLY WARMING TEMPS WHERE RAINS WERE STEADIER AND HEAVIER. THE BEST CHANCE FOR TEMPS RISING THROUGH THE 60S LATE SHOULD BE TO THE S OF I-16. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/... WEDNESDAY...A STRONG SHORTWAVE TROUGH CURRENTLY OVER THE SOUTHERN PLAINS WILL STEADILY SHIFT EAST EARLY WEDNESDAY...BECOMING MORE STRETCHED/SHEARED AS IT MOVES INTO THE TENNESSEE/LOWER MISSISSIPPI VALLEYS BY MIDDAY. THIS UPPER LEVEL ENERGY WILL SUPPORT THE DEVELOPMENT OF A SURFACE LOW LIFTING FROM THE GULF COAST STATES INTO THE UPSTATE CAROLINAS AS THE DAY PROGRESSES. NUMERICAL MODELS ARE IN DECENT AGREEMENT THAT THE ASSOCIATED WARM FRONT WILL BE LOCATED RIGHT ALONG THE NORTHERN BORDER OF THE FORECAST AREA...PERHAPS AROUND THE SANTEE RIVER...BY DAYBREAK WEDNESDAY. AS A RESULT...TEMPERATURES WILL RISE WELL ABOVE SEASONAL NORMALS INTO THE UPPER 60S NORTH TO LOWER 70S SOUTH. BOTH 12Z NAM AND 12Z GFS SOLUTIONS INDICATE LOW TO MODERATE INSTABILITY INCREASING ACROSS MUCH OF THE FORECAST AREA THROUGH THE MORNING AND AFTERNOON HOURS...WITH CAPE VALUES POSSIBLY REACHING 1000 J/KG OVER THE CHARLESTON TRI COUNTY REGION BY 18Z. THE SOUTHEAST STATES WILL BE IN THE VICINITY OF THE RIGHT REAR OF A 100 KT 500 MB JET AND A 30 TO 40 KT LOW LEVEL JET. THE COMBINATION OF MODERATELY FAVORABLE INSTABILITY AND DECENT SHEAR SUGGESTS ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE...WITH A FEW THUNDERSTORMS POTENTIALLY BECOMING STRONG AND ORGANIZED. STORM PREDICTION CENTER HAS PLACED THE SOUTHERN HALF OF THE FORECAST AREA...WHERE TEMPERATURES AND DEWPOINTS WILL BE HIGHEST...WITHIN A SLIGHT RISK FOR SEVERE THUNDERSTORM DEVELOPMENT. WILL ADD MENTION OF ISOLATED STORMS POSSIBLY BECOMING SEVERE IN THE HAZARDOUS WEATHER OUTLOOK. IT SHOULD BE NOTED THAT THICK CLOUD COVER AND MARGINAL LAPSE RATES COULD NEGATIVELY IMPACT STORM ORGANIZATION...AND MUCH UNCERTAINTY IN THUNDERSTORM STRENGTH AND COVERAGE REMAINS. WEDNESDAY NIGHT...AS THE SURFACE LOW CONTINUES TO LIFT NORTH/NORTHEAST TOWARD THE MID ATLANTIC COASTLINE...A TRAILING COLD FRONT WILL PULL THROUGH THE FORECAST AREA BY THE EVENING HOURS. SHOWER AND THUNDERSTORM CHANCES WILL THUS END FAIRLY QUICKLY FROM WEST TO EAST BETWEEN 00Z AND 06Z WEDNESDAY NIGHT...WITH DRIER DEEP LAYER AIR MOVING IN BEHIND THE DEPARTING FRONT. COLD ADVECTION OVERNIGHT WILL ALLOW TEMPERATURES TO FALL INTO THE UPPER 30S INLAND TO THE LOWER 40S NEAR THE COAST. THURSDAY AND FRIDAY...WEAK SURFACE HIGH PRESSURE WILL BUILD INTO THE REGION AND SET UP PREVAILING WEST/NORTHWEST SYNOPTIC FLOW. EXPECT DRY CONDITIONS AND SLIGHTLY COOLER TEMPERATURES...WITH HIGHS GENERALLY REACHING THE MID 60S THURSDAY AND THE MID TO UPPER 60S FRIDAY. LOW TEMPERATURES THURSDAY NIGHT WILL REFLECT IMPROVED RADIATIONAL COOLING CONDITIONS UNDER CLEAR SKIES AND LIGHTER WINDS...RANGING FROM THE MID TO UPPER 30S INLAND TO THE LOWER 40S NEAR THE COAST. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AN ARCTIC FRONT WILL PUSH THROUGH THE SOUTHEAST STATES LATE SATURDAY AHEAD OF A SHARP UPPER TROUGH DIVING TOWARD THE AREA FROM THE GREAT LAKES/CENTRAL PLAINS REGION. THERE IS SOME EVIDENCE IN MEDIUM RANGE MODEL SOLUTIONS OF ISOLATED RAIN ASSOCIATED WITH THE UPPER TROUGH PROGRESSION TO SUPPORT SLIGHT CHANCE POPS FOR THE NORTHERN HALF OF THE AREA SATURDAY NIGHT. GUIDANCE IS STILL SHOWING HIGHS IN THE UPPER 50S TO LOWER 60S AHEAD OF THE FRONT ON SATURDAY...BUT SUSPECT TEMPERATURES WILL BE FALLING DURING THE AFTERNOON DEPENDING ON THE EXACT TIMING OF THE FRONT. THERE IS SOME CONCERN ABOUT THE POTENTIAL FOR SOME BRIEF WINTRY PRECIP WITH THIS FRONT...AS MODELS DROP 850MB TEMPS TO -2 TO -4C BY 00Z SUNDAY. HOWEVER...BOUNDARY LATER TEMPS COULD BE TOO WARM. PREFER TO CONTINUE MONITORING MODEL TRENDS FOR THIS PERIOD. THE DEEP ARCTIC UPPER TROUGH PUSHES OFFSHORE INTO THE ATLANTIC SUNDAY...THEN ZONAL FLOW TO SLIGHT RIDGING BUILDS BACK INTO THE UPPER LEVELS FOR MONDAY. BELOW CLIMO TEMPS EXPECTED FOR SUNDAY AND MONDAY WITH HIGHS IN THE 50S...AS WELL AS THE POTENTIAL FOR FREEZING OVERNIGHT/EARLY MORNING TEMPS...ESPECIALLY MONDAY MORNING. EXPECT MODERATING TEMPS BY TUESDAY AS MODELS SHOW ANOTHER STRONG UPPER TROUGH AND ASSOCIATED SURFACE FRONT MOVING TOWARD THE REGION. DUE TO UNCERTAINTY IN THE TIMING OF THIS FEATURE...HAVE GONE WITH SLIGHT CHANCE TO CHANCE POPS. && .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/... THE 06Z TAF PACKAGE ENCOMPASSES A COMPLEX PERIOD. INITIALLY... WIDESPREAD RAIN NORTH OF A WARM FRONT WILL BE HEAVY AT TIMES AND WILL BE ACCOMPANIED BY FLIGHT CONDITIONS RANGING FROM MVFR TO LIFR. ELEVATED THUNDERSTORMS COULD IMPACT KSAV AND KCHS AT ANY TIME THROUGH THIS MORNING. HOWEVER...PRECISE TIMING WILL REMAIN DIFFICULT AND HAVE OPTED TO ISSUE AMENDMENTS AS REQUIRED TO ADDRESS NEAR TERM CONVECTIVE TRENDS. MAINTAINED LOW LEVEL WIND SHEAR TO ACCOUNT FOR SW WINDS AROUND 40 KT JUST ABOVE THE SURFACE OVERNIGHT INTO WEDNESDAY MORNING. NORTHWARD PROGRESS OF THE WARM FRONT WILL TURN WINDS TO THE S/SW AND SHOULD EVENTUALLY USHER IMPROVING CEILINGS/VISIBILITY LATER THIS MORNING...AND PREVAILING VFR CONDITIONS SHOULD DEVELOP BY LATE MORNING/EARLY AFTERNOON. HOWEVER...ADDITIONAL SHOWERS/THUNDERSTORMS WILL DEVELOP AHEAD OF AN ADVANCING COLD FRONT...AND THIS PRECIPITATION COULD IMPACT TERMINALS WITH BRIEF FLIGHT RESTRICTIONS UNTIL LATE AFTERNOON. THUNDERSTORMS COULD ACCOMPANY COLD FROPA AT BOTH TERMINALS...BUT A SLIGHTLY BETTER CHANCE FOR THUNDERSTORMS SHOULD FOCUS AROUND KSAV. THIS EVENING...POST COLD FROPA CONDITIONS SHOULD RETURN TO VFR WITH NO ADDITIONAL FLIGHT RESTRICTIONS EXPECTED. EXTENDED AVIATION OUTLOOK...MAINLY VFR THROUGH THE WEEKEND. && .MARINE... A WARM FRONT AND ASSOCIATED LOW LEVEL JETTING/INCREASING SOUTHERLY FLOW HAD ADVANCED INTO GA WATERS AND WILL CONTINUE TO ADVANCE NORTH THROUGH SC WATERS OVERNIGHT. SOME GUSTS TO 25 KT WILL OCCUR ACROSS THE OFFSHORE GA WATERS. ELSEWHERE IT WILL BE CLOSER TO DAYBREAK WEDNESDAY WHEN THE WINDS BECOME MORE GUSTY. WE HAVE THE SMALL CRAFT ADVISORY FOR OFFSHORE GA WATERS TONIGHT. WEDNESDAY THROUGH SUNDAY...SMALL CRAFT ADVISORY CONDITIONS WILL BE ONGOING FOR MUCH OF THE MARINE AREA WEDNESDAY...AS A SURFACE LOW PASSES WELL NORTHWEST OF THE WATERS AND A COLD FRONT CROSSES OFFSHORE DURING THE EVENING HOURS. EXPECT WINDS AND SEAS TO GRADUALLY FALL BELOW ADVISORY LEVELS LATE WEDNESDAY NIGHT INTO THURSDAY MORNING...WITH HIGH PRESSURE BUILDING OVER THE REGION FROM THE WEST. A STRONGER COLD FRONT AND HIGH PRESSURE IS EXPECTED TO SUPPORT ANOTHER SURGE IN WINDS TO ADVISORY LEVELS LATER SATURDAY AND SATURDAY NIGHT. THERE IS EVEN THE POTENTIAL FOR SOME MARGINAL GALE CONDITIONS SATURDAY NIGHT...HOWEVER UNCERTAINTY IS TOO HIGH TO MENTION AT THIS POINT. WINDS AND SEAS WILL BE GRADUALLY FALLING BACK BELOW HIGHLIGHTS SUNDAY...AS HIGH PRESSURE BUILDS OVER THE REGION AGAIN. && .HYDROLOGY... LOCALLY HEAVY RAIN WILL CONTINUE OVERNIGHT...AND PERIODS OF DROUGHT-RELIEVING RAINS TO CONTINUE THROUGH WEDNESDAY. STORM TOTAL RAINFALL AMOUNTS OF 2-4 INCHES WILL BE SPREAD OVER A LONG ENOUGH PERIOD TO PRECLUDE WIDESPREAD FLASH FLOOD ISSUES... BUT SEVERAL OF OUR RIVERS ARE EXPECTED TO APPROACH FLOOD STAGE LATER IN THE WEEK. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 10 PM EST THIS EVENING FOR AMZ352. SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR AMZ374. SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 5 AM EST THURSDAY FOR AMZ350. && $$ SYNOPSIS... NEAR TERM...SPR SHORT TERM...79 LONG TERM...RFM AVIATION...SPR MARINE...SPR HYDROLOGY...
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1258 AM EST WED FEB 13 2013 .SYNOPSIS... A STATIONARY FRONT OVER FAR SOUTH GEORGIA WILL LIFT NORTH INTO THE AREA AS A WARM FRONT LATE TONIGHT...WHILE GULF LOW PRESSURE PASSES TO THE WEST. A COLD FRONT WILL SWEEP THROUGH THE AREA LATE WEDNESDAY... WITH HIGH PRESSURE EXPECTED TO BUILD ACROSS THE REGION THURSDAY INTO EARLY SATURDAY. ANOTHER COLD FRONT WILL PUSH THROUGH THE AREA SATURDAY...FOLLOWED BY STRONGER HIGH PRESSURE AND COOLER CONDITIONS INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... EARLY MORNING SURFACE ANALYSIS REMAINED COMPLEX AS THE WARM FRONT HAS ADVANCED TO AROUND ALTAMAHA SOUND...AHEAD OF A SURFACE LOW CENTERED NEAR AMG. THIS LOW AND ASSOCIATED WIDESPREAD PRECIPITATION HAD THUS FAR DELAYED THE NORTHWARD PROGRESS OF THE WARM FRONT ACROSS SOUTHERN GEORGIA. NORTH OF THE WARM FRONT... WIDESPREAD RAINS OCCASIONALLY PUNCTUATED BY ELEVATED THUNDERSTORMS CONTINUED WITHIN BREAD SWATH OF DEEP LAYER ASCENT/MOISTURE FLOWING ACROSS THE REGION FROM S/SW TO E/NE. MODELS DOING A REASONABLE JOB WITH RAIN DEPICTION BUT MAY STRUGGLE OVERNIGHT WITH THE DETAIL OF THE WARM FRONTAL PROGRESSION GIVEN THE PRESENCE OF THE SURFACE LOW OVER SE GA AND COMPLICATED SURFACE LAYERED STABILITY PROFILES. TEMPS WERE IN THE MID 50S MOST AREAS AS NEAR SATURATION EVIDENT ON SOUNDING PROFILES. OVERNIGHT...A FAIRLY UNSTABLE MID LEVEL ENVIRONMENT WILL SPREAD OVER THE FORECAST REGION BUT GIVEN THE CURRENT RADAR TRENDS AND A MORE BELIEVABLE RUC FORECAST...THE POTENTIAL FOR SEVERE WEATHER OVERNIGHT DOES NOT APPEAR TOO IMPRESSIVE DESPITE INCREASING SHEAR PROFILES. EVEN ACROSS FAR SOUTHERN COUNTIES/CLOSER TO THE WARM FRONT WHERE THUNDERSTORMS WILL REMAIN MOST COMMON...THE POTENTIAL FOR ISOLATED SEVERE WEATHER WILL BE SOMEWHAT GREATER BUT STILL LIMITED DUE TO IMPACTS OF ONGOING/WIDESPREAD PRECIP ON SURFACE BASED INSTABILITY. CATEGORICAL POPS REMAIN IN ORDER OVERNIGHT. FORECASTS CONTINUE TO INDICATE ONLY SLOWLY WARMING TEMPS WHERE RAINS WERE STEADIER AND HEAVIER. THE BEST CHANCE FOR TEMPS RISING THROUGH THE 60S LATE SHOULD BE TO THE S OF I-16. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/... WEDNESDAY...A STRONG SHORTWAVE TROUGH CURRENTLY OVER THE SOUTHERN PLAINS WILL STEADILY SHIFT EAST EARLY WEDNESDAY...BECOMING MORE STRETCHED/SHEARED AS IT MOVES INTO THE TENNESSEE/LOWER MISSISSIPPI VALLEYS BY MIDDAY. THIS UPPER LEVEL ENERGY WILL SUPPORT THE DEVELOPMENT OF A SURFACE LOW LIFTING FROM THE GULF COAST STATES INTO THE UPSTATE CAROLINAS AS THE DAY PROGRESSES. NUMERICAL MODELS ARE IN DECENT AGREEMENT THAT THE ASSOCIATED WARM FRONT WILL BE LOCATED RIGHT ALONG THE NORTHERN BORDER OF THE FORECAST AREA...PERHAPS AROUND THE SANTEE RIVER...BY DAYBREAK WEDNESDAY. AS A RESULT...TEMPERATURES WILL RISE WELL ABOVE SEASONAL NORMALS INTO THE UPPER 60S NORTH TO LOWER 70S SOUTH. BOTH 12Z NAM AND 12Z GFS SOLUTIONS INDICATE LOW TO MODERATE INSTABILITY INCREASING ACROSS MUCH OF THE FORECAST AREA THROUGH THE MORNING AND AFTERNOON HOURS...WITH CAPE VALUES POSSIBLY REACHING 1000 J/KG OVER THE CHARLESTON TRI COUNTY REGION BY 18Z. THE SOUTHEAST STATES WILL BE IN THE VICINITY OF THE RIGHT REAR OF A 100 KT 500 MB JET AND A 30 TO 40 KT LOW LEVEL JET. THE COMBINATION OF MODERATELY FAVORABLE INSTABILITY AND DECENT SHEAR SUGGESTS ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE...WITH A FEW THUNDERSTORMS POTENTIALLY BECOMING STRONG AND ORGANIZED. STORM PREDICTION CENTER HAS PLACED THE SOUTHERN HALF OF THE FORECAST AREA...WHERE TEMPERATURES AND DEWPOINTS WILL BE HIGHEST...WITHIN A SLIGHT RISK FOR SEVERE THUNDERSTORM DEVELOPMENT. WILL ADD MENTION OF ISOLATED STORMS POSSIBLY BECOMING SEVERE IN THE HAZARDOUS WEATHER OUTLOOK. IT SHOULD BE NOTED THAT THICK CLOUD COVER AND MARGINAL LAPSE RATES COULD NEGATIVELY IMPACT STORM ORGANIZATION...AND MUCH UNCERTAINTY IN THUNDERSTORM STRENGTH AND COVERAGE REMAINS. WEDNESDAY NIGHT...AS THE SURFACE LOW CONTINUES TO LIFT NORTH/NORTHEAST TOWARD THE MID ATLANTIC COASTLINE...A TRAILING COLD FRONT WILL PULL THROUGH THE FORECAST AREA BY THE EVENING HOURS. SHOWER AND THUNDERSTORM CHANCES WILL THUS END FAIRLY QUICKLY FROM WEST TO EAST BETWEEN 00Z AND 06Z WEDNESDAY NIGHT...WITH DRIER DEEP LAYER AIR MOVING IN BEHIND THE DEPARTING FRONT. COLD ADVECTION OVERNIGHT WILL ALLOW TEMPERATURES TO FALL INTO THE UPPER 30S INLAND TO THE LOWER 40S NEAR THE COAST. THURSDAY AND FRIDAY...WEAK SURFACE HIGH PRESSURE WILL BUILD INTO THE REGION AND SET UP PREVAILING WEST/NORTHWEST SYNOPTIC FLOW. EXPECT DRY CONDITIONS AND SLIGHTLY COOLER TEMPERATURES...WITH HIGHS GENERALLY REACHING THE MID 60S THURSDAY AND THE MID TO UPPER 60S FRIDAY. LOW TEMPERATURES THURSDAY NIGHT WILL REFLECT IMPROVED RADIATIONAL COOLING CONDITIONS UNDER CLEAR SKIES AND LIGHTER WINDS...RANGING FROM THE MID TO UPPER 30S INLAND TO THE LOWER 40S NEAR THE COAST. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AN ARCTIC FRONT WILL PUSH THROUGH THE SOUTHEAST STATES LATE SATURDAY AHEAD OF A SHARP UPPER TROUGH DIVING TOWARD THE AREA FROM THE GREAT LAKES/CENTRAL PLAINS REGION. THERE IS SOME EVIDENCE IN MEDIUM RANGE MODEL SOLUTIONS OF ISOLATED RAIN ASSOCIATED WITH THE UPPER TROUGH PROGRESSION TO SUPPORT SLIGHT CHANCE POPS FOR THE NORTHERN HALF OF THE AREA SATURDAY NIGHT. GUIDANCE IS STILL SHOWING HIGHS IN THE UPPER 50S TO LOWER 60S AHEAD OF THE FRONT ON SATURDAY...BUT SUSPECT TEMPERATURES WILL BE FALLING DURING THE AFTERNOON DEPENDING ON THE EXACT TIMING OF THE FRONT. THERE IS SOME CONCERN ABOUT THE POTENTIAL FOR SOME BRIEF WINTRY PRECIP WITH THIS FRONT...AS MODELS DROP 850MB TEMPS TO -2 TO -4C BY 00Z SUNDAY. HOWEVER...BOUNDARY LATER TEMPS COULD BE TOO WARM. PREFER TO CONTINUE MONITORING MODEL TRENDS FOR THIS PERIOD. THE DEEP ARCTIC UPPER TROUGH PUSHES OFFSHORE INTO THE ATLANTIC SUNDAY...THEN ZONAL FLOW TO SLIGHT RIDGING BUILDS BACK INTO THE UPPER LEVELS FOR MONDAY. BELOW CLIMO TEMPS EXPECTED FOR SUNDAY AND MONDAY WITH HIGHS IN THE 50S...AS WELL AS THE POTENTIAL FOR FREEZING OVERNIGHT/EARLY MORNING TEMPS...ESPECIALLY MONDAY MORNING. EXPECT MODERATING TEMPS BY TUESDAY AS MODELS SHOW ANOTHER STRONG UPPER TROUGH AND ASSOCIATED SURFACE FRONT MOVING TOWARD THE REGION. DUE TO UNCERTAINTY IN THE TIMING OF THIS FEATURE...HAVE GONE WITH SLIGHT CHANCE TO CHANCE POPS. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... THE 06Z TAF PACKAGE ENCOMPASSES A COMPLEX PERIOD. INITIALLY... WIDESPREAD RAIN NORTH OF A WARM FRONT WILL BE HEAVY AT TIMES AND WILL BE ACCOMPANIED BY FLIGHT CONDITIONS RANGING FROM MVFR TO LIFR. ELEVATED THUNDERSTORMS COULD IMPACT KSAV AND KCHS AT ANY TIME THROUGH THIS MORNING. HOWEVER...PRECISE TIMING WILL REMAIN DIFFICULT AND HAVE OPTED TO ISSUE AMENDMENTS AS REQUIRED TO ADDRESS NEAR TERM CONVECTIVE TRENDS. MAINTAINED LOW LEVEL WIND SHEAR TO ACCOUNT FOR SW WINDS AROUND 40 KT JUST ABOVE THE SURFACE OVERNIGHT INTO WEDNESDAY MORNING. NORTHWARD PROGRESS OF THE WARM FRONT WILL TURN WINDS TO THE S/SW AND SHOULD EVENTUALLY USHER IMPROVING CEILINGS/VISIBILITY LATER THIS MORNING...AND PREVAILING VFR CONDITIONS SHOULD DEVELOP BY LATE MORNING/EARLY AFTERNOON. HOWEVER...ADDITIONAL SHOWERS/THUNDERSTORMS WILL DEVELOP AHEAD OF AN ADVANCING COLD FRONT...AND THIS PRECIPITATION COULD IMPACT TERMINALS WITH BRIEF FLIGHT RESTRICTIONS UNTIL LATE AFTERNOON. THUNDERSTORMS COULD ACCOMPANY COLD FROPA AT BOTH TERMINALS...BUT A SLIGHTLY BETTER CHANCE FOR THUNDERSTORMS SHOULD FOCUS AROUND KSAV. THIS EVENING...POST COLD FROPA CONDITIONS SHOULD RETURN TO VFR WITH NO ADDITIONAL FLIGHT RESTRICTIONS EXPECTED. EXTENDED AVIATION OUTLOOK...MAINLY VFR THROUGH THE WEEKEND. && .MARINE... A WARM FRONT AND ASSOCIATED LOW LEVEL JETTING/INCREASING SOUTHERLY FLOW HAD ADVANCED INTO GA WATERS AND WILL CONTINUE TO ADVANCE NORTH THROUGH SC WATERS OVERNIGHT. SOME GUSTS TO 25 KT WILL OCCUR ACROSS THE OFFSHORE GA WATERS. ELSEWHERE IT WILL BE CLOSER TO DAYBREAK WEDNESDAY WHEN THE WINDS BECOME MORE GUSTY. WE HAVE THE SMALL CRAFT ADVISORY FOR OFFSHORE GA WATERS TONIGHT. WEDNESDAY THROUGH SUNDAY...SMALL CRAFT ADVISORY CONDITIONS WILL BE ONGOING FOR MUCH OF THE MARINE AREA WEDNESDAY...AS A SURFACE LOW PASSES WELL NORTHWEST OF THE WATERS AND A COLD FRONT CROSSES OFFSHORE DURING THE EVENING HOURS. EXPECT WINDS AND SEAS TO GRADUALLY FALL BELOW ADVISORY LEVELS LATE WEDNESDAY NIGHT INTO THURSDAY MORNING...WITH HIGH PRESSURE BUILDING OVER THE REGION FROM THE WEST. A STRONGER COLD FRONT AND HIGH PRESSURE IS EXPECTED TO SUPPORT ANOTHER SURGE IN WINDS TO ADVISORY LEVELS LATER SATURDAY AND SATURDAY NIGHT. THERE IS EVEN THE POTENTIAL FOR SOME MARGINAL GALE CONDITIONS SATURDAY NIGHT...HOWEVER UNCERTAINTY IS TOO HIGH TO MENTION AT THIS POINT. WINDS AND SEAS WILL BE GRADUALLY FALLING BACK BELOW HIGHLIGHTS SUNDAY...AS HIGH PRESSURE BUILDS OVER THE REGION AGAIN. && .HYDROLOGY... LOCALLY HEAVY RAIN WILL CONTINUE OVERNIGHT...AND PERIODS OF DROUGHT-RELIEVING RAINS TO CONTINUE THROUGH WEDNESDAY. STORM TOTAL RAINFALL AMOUNTS OF 2-4 INCHES WILL BE SPREAD OVER A LONG ENOUGH PERIOD TO PRECLUDE WIDESPREAD FLASH FLOOD ISSUES... BUT SEVERAL OF OUR RIVERS ARE EXPECTED TO APPROACH FLOOD STAGE LATER IN THE WEEK. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 10 PM EST THIS EVENING FOR AMZ352. SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR AMZ374. SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 5 AM EST THURSDAY FOR AMZ350. && $$ SYNOPSIS... NEAR TERM...SPR SHORT TERM...79 LONG TERM...RFM AVIATION...SPR MARINE...SPR HYDROLOGY...
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
117 AM EST WED FEB 13 2013 .AVIATION... WARM AIR ADVECTION WAS INCREASING OVER THE WESTERN GREAT LAKES REGION. A RECEDING SC CLOUD BANK WAS OVER LOWER MICHIGAN AND EXTENDED INTO NRN INDIANA. HAVE MADE SOME MINOR ADJUSTMENTS IN THE SCATTERING OUT OF THIS CLOUD LAYER. OTHERWISE...CONDITIONS WILL BECOME VFR EARLY IN THE TAF PERIOD AND SHOULD PERSIST AS THE LOW LEVEL FLOW REMAINS FROM THE WEST IN A RELATIVELY DRY AIRMASS. && .PREV DISCUSSION... /ISSUED 307 PM EST TUE FEB 12 2013/ SHORT TERM... SFC RIDGING INVOF OF OH RVR WILL BREAK DOWN INADV OF SW CLIPPER DROPPING OUT OF SWRN CANADA WED AFTN. HWVR NO SENSIBLE WX OF CONSEQUENCE XPCD WITHIN THIS EVOLUTION THROUGH THIS PD. MIXING/EROSION OF SC CLD DECK ONGOING THIS AFTN W/PARTIAL SUNSHINE NOW ACRS MUCH OF ERN HALF CWA BUT WRN FLANK EXTENDING BACK INTO NE IL HOLDING TOUGH AND MAY POSE A BUST OVERNIGHT WRT MIN TEMPS. ATTM SHRT TERM RUC GIVES A NOD TWD PRIOR EVEN MOS BLEND. OTRWS AT LEAST PARTIAL INSOLATION XPCD AGAIN ON WED W/STGR DIURNAL WITHIN MODEST LL SWRLY FLW. IN FACT MOS MAX TEMP SPLIT ESSENTIALLY EVEN AND REFLECTED IN GRIDDED MAXS. LONG TERM... /THURSDAY THROUGH TUESDAY/ ACTIVE PATTERN IN STORE FOR THE LONG TERM PERIOD. ONE MORE DAY OF ABOVE NORMAL TEMPS ON TAP FOR THURSDAY AHEAD OF SHOT OF ARCTIC AIR DROPPING SE ACROSS THE PLAINS. STRONG FORCING ALONG THE FRONT WILL STIR UP AT LEAST A CHC FOR RAIN OR SNOW SHOWERS BUT OVERALL QPF APPEARS MINIMAL AT THIS POINT. POPS STILL HELD IN CHC/SCHC RANGE FOR NOW. GREATER FOCUS THEN TURNS TOWARDS LAKE EFFECT POTENTIAL AS STG NW FLOW SETS UP WITH SFC-850 MB DELTA T`S PUSHING 20 C AND SFC-700 MB DELTA T`S PUSHING UPR 20S. NAM/WRF SHOW A PERIOD OF FAVORABLE COLLOCATION OF DGZ AND TOP OF STRONG OMEGA. INVERSION HGTS BEGIN TO CLIMB...ESPECIALLY DURING THE DAY FRIDAY WHEN SOME ADDITIONAL SYNOPTIC MSTR ARRIVES AND A REINFORCING SHOT OF COLD AIR. HAVE TENDED TO FOCUS GREATEST POPS FRIDAY TO MATCH WITH THE ABOVE SETUP. ACCUMS AT THIS POINT APPEAR TO BE ON THE LIGHTER SIDE BUT WILL NEED TO BE WATCHED IN COMING FORECASTS. WHILE AN OUTLIER...SEVERAL RUNS OF THE GEM NHEM MODEL HAVE BEEN SHOWING PHASING OF N/S STREAM SYSTEMS SOONER THAN LATER WITH A STORM AFFECTING THE GREAT LAKES VS EAST COAST. ECMWF/GFS DO NOT PHASES THE ENERGY UNTIL REACHING EAST COAST SO AT THIS POINT HAVE TO PUT IT ON THE BACK BURNER BUT WILL NEED TO WATCH. LAKE EFFECT WILL LINGER POTENTIALLY THROUGH MUCH OF THE WEEKEND WITH CONTINUED NW FLOW AND 850 MB RIDGING STILL TO THE WEST UNTIL LATE SUNDAY. NEXT SYSTEM TO FOCUS ON WILL BE WHAT LOOKS LIKE A PANHANDLE HOOK COMING TOWARDS THE REGION MONDAY NIGHT INTO TUESDAY. SIGNALS POINT TOWARDS MEASURABLE PRECIP FOR PARTS OF THE AREA BUT EXACT TRACK AND AMOUNT OF COLD AIR REMAIN QUESTIONABLE THIS FAR OUT IN THE FORECAST. HAVE WENT WITH MID-HIGH END CHC POPS WITH MIX OF RAIN OR SNOW WITH LIKELY REFINEMENT OF FORECAST TO COME OVER THE NEXT SEVERAL DAYS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...T LONG TERM...FISHER AVIATION...SKIPPER
AREA FORECAST DISCUSSION
NWS JACKSON KY
422 AM EST WED FEB 13 2013 .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 423 AM EST WED FEB 13 2013 CURRENT 09Z ANALYSIS ACROSS THE AREA HAS WIDESPREAD CLOUD COVER OVER EASTERN KENTUCKY WITH PRECIP ALONG THE TN AND KY BORDER IN SOUTH CENTRAL KY DEVELOPING AND MOVING INTO THE AREA. CURRENT TEMPERATURES ACROSS THE SOUTHERN PORTION OF THE AREA ARE IN THE LOW 40S TO UPPER 30S. HOWEVER SURFACE TEMPS ALONG AND NORTH OF THE MOUNTAIN PARKWAY ARE COLD ENOUGH TO SUSTAIN SOME SNOWFALL AS THE PRECIP WILL CREEP INTO THE NORTHERN PORTION OF THE CWA BY 12Z. MET SAT DATA CURRENTLY SHOWS THE DEVELOPING SURFACE LOW OVER THE LOWER TN VALLEY AND SHIFTING OFF TO THE NORTHEAST. THE UPPER LOW IS LOCATED OVER SOUTHERN IL MOVING TO THE EAST NORTHEAST. CURRENT SHORT TERM MODELS INDICATE A BAND OF HEAVY PRECIP SETTING UP. THE CHALLENGE HERE IS THE LOCATION OF THE DEVELOPMENT. BOTH THE NAM AND GFS HAVE INDICATED A BAND OF HEAVIER PRECIP JUST SOUTH OF THE OH RIVER AND ALSO ANOTHER BAND GOING THROUGH CENTRAL EASTERN KY. THE HI RES HRRR ALSO SHOWS THIS BUT WITH THE SOUTHERN BAND NOT AS INTENSE. BASED ON CURRENT WV SHOWING MID LEVEL MOISTURE AND ADVECTING TOWARD THE UPPER OH VALLEY...HAVE GONE WITH THE BLUEGRASS AND LOCATIONS NORTH OF THE MOUNTAIN PARKWAY TO RECEIVE UP TO AN INCH OF SNOWFALL. CURRENT THOUGH IS WITH THE SOUTHEAST KY STILL QUITE WARMER THAN THE NORTH LOCATIONS...THE BAND INDICATED THROUGH THE CENTRAL PORTION OF EAST KY...WILL MAINLY BE A RAIN PRODUCER WITH THE BEST CHANCE FOR ACCUMULATING SNOW ION THE HIGHER TERRAIN ALONG THE VA BORDER. AS WELL...NAM MODEL SOUNDINGS STILL SHOW A POOR DENDRITE GROWTH ZONE THROUGH MUCH OF THE EVENT...LOCATED FROM THE JKL POINT AND SOUTH. BASED ON ALL THESE FACTORS...HAVE KEPT THE SPS GOING WITH THE INCH POSSIBLE NORTH OF THE MOUNTAIN PARKWAY AND IN THE HIGHER TERRAIN ALONG THE VA BORDER. IF THE BAND IN THE NORTH DOES SLIDE SOUTH A BIT...THE BLUE GRASS COUNTIES WILL QUICKLY REACH ADVISORY CRITERIA. FOR THE REST OF THE SHORT TERM...A PROGRESSIVE PATTERN REMAINS...SUCH THAT...LOCATIONS THAT FINALLY BECOME COLD ENOUGH TO SUPPORT SNOW THIS EVENING AND TONIGHT...MUCH OF THE MOISTURE WILL BE OUT OF THE AREA WITH A FEW FLURRIES POSSIBLE. THE PATTERN WILL ALLOW A BRIEF STAY FOR THIS COLDER AIR MASS AS THURSDAY HIGH TEMPS WILL QUICKLY WARM INTO THE UPPER 40S...MELTING ANY SNOW THAT FALLS TODAY AND TONIGHT. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 341 AM EST WED FEB 13 2013 THE MODEL START OFF IN FAIRLY GOOD AGREEMENT WITH AN UPPER TROUGH EXTENDING ACROSS THE MIDWEST. THIS UPPER TROUGH WILL PUSH A WEAK FRONT ACROSS THE AREA ON FRIDAY BRINGING INITIALLY A MIX OF RAIN AND SNOW IN THE MORNING AND THEN TURNING TO ALL RAIN AS IT WARMS UP A LITTLE IN THE AFTERNOON AND THEN A MIX OF RAIN AND SNOW AGAIN IN THE EVENING WHEN THINGS COOL OFF AGAIN. AT WORST...A DUSTING OF SNOW IS EXPECTED WITH THIS SYSTEM. SOME FLURRIES OR VERY LIGHT SNOW IS POSSIBLE ON SATURDAY AS THE UPPER TROUGH MOVES THROUGH THE AREA. THIS IS ALSO WHERE THE MODELS REALLY BEGIN TO DIVERGE WITH THE ECMWF ABOUT 12 HOURS SLOWER WITH THE UPPER TROUGH PASSAGE. ALSO THE ECMWF HAS A MUCH SHARPER AND DEEPER UPPER TROUGH THAN THE GFS. THE MODELS THEN GET INTO BETTER AGREEMENT WITH A MORE ZONAL PATTERN DEVELOPING ACROSS THE US. THE NEXT SYSTEM TO MOVE ACROSS EASTERN KENTUCKY WILL BE ON TUESDAY. HERE THE ECMWF IS THE FASTER OF THE TWO SYSTEMS. DECIDED TO GO WITH THE FASTER ECMWF FOR THE TUESDAY SYSTEM. THE PATTERN THUS REMAINS ACTIVE...HOWEVER NO MAJOR SYSTEMS WITH BIG IMPACT ARE EXPECTED. FOR THE TEMPERATES...GENERALLY NUDGED THE MODEL BLEND TOWARD THE NEW AND GENERALLY WARMER ECMWF RAW DATA FOR THE TEMPERATURE FORECAST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 151 AM EST WED FEB 13 2013 WITH STILL A DRY LOWER LAYER TO OVERCOME...MVFR AND IFR CEILINGS WILL HOLD OFF TILL NEAR DAY BREAK FOR TAF SITES. PRECIP WILL FALL AFTER 12Z ACROSS THE AREA LOWERING VIS TO MVFR AND IFR CONDITIONS ALONG WITH CEILINGS REMAINING OVER THE AREA THROUGH THE REST OF THE TAF PERIOD. PRECIP SHOULD END ACROSS EASTERN KENTUCKY BY 03Z WITH CEILINGS REMAINING THROUGH THE REST OF THE TAF PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...SHALLENBERGER LONG TERM...SHALLENBERGER AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
329 AM EST WED FEB 13 2013 .Short Term (Now through Thursday)... Issued at 325 AM EST Wed Feb 13 2013 ...Light Slushy Snow Accumulations Possible Today... As of 745Z, an upper trough was over MO with sfc low pressure over the Gulf States. Precipitation associated with this system stretched from western KY to eastern OK as of 745Z with rain observed over most areas ESE of the upper trough and snow or a rain/snow mix observed over portions of OK/MO/AR in the upper level trough. The 6Z NAM12 and last few RAP runs seem to have the best handle on the area of precipitation and general schematic of ptype. Overall timing of the best precip and forcing seems to be a little earlier than previously thought. Looks like the best dynamics and precip should fall over our region between 12-18Z. Also, the latest runs of the NAM and RAP have moved the best band of moderate to heavy precip...probably a heavy wet snow as observed out in MO...to the north. According to these models, the best snow band in which we could see 1-2 inches of wet, slushy snow would be in a corridor along the Ohio River to along the Western KY and Bluegrass Parkways. Other areas over southern Indiana and south central KY may see a brief mix of rain/snow...enough to create a dusting to a half inch before quickly melting off. There is still some uncertainty in where the band of moderate to heavy snow will set up so stay tuned to morning forecast updates. Also, because of the uncertainty, will continue with the SPS product instead of going with an advisory although one may be needed later this morning. So for today expect light rain to overspread the area before sunrise with possibly some snow grains mixing in over southern Indiana and northern KY at precip onset due to a deeper cold layer. After sunrise we`ll start to see colder air filter in with the upper trough causing precip to change over to a rain/snow mix and then probably all snow for a time over southern Indiana and central KY. The morning hours after sunrise through early afternoon will be the best time for a period of moderate to heavy wet snow resulting in slushy snow accumulations as high as 1-2 inches over north central KY. This period of wintry precip may cause some travel issues. We`ll continue to see a early afternoon before precip exits to our east by late afternoon/early evening. Once snow comes to an end over any location, quick melting can be expected as sfc temps are expected to be above freezing today. In fact, most locations will still top out in the upper 30s to lower 40s this afternoon despite any morning/early afternoon snow. For tonight and Thurs, expect dry conditions with partly cloudy skies. Low temps will be in the upper 20s to lower 30s tonight. An upper level trough and cold front will approach the region by Thurs evening. Ahead of the trough, though, Thurs will be quite warm with a strong southerly flow in place. High temps Thurs should be in the low to mid 50s. .Long Term (Thursday Night - Tuesday)... Issued at 320 AM EST Wed Feb 13 2013 ...A few shots for snow showers followed by a warm up and another strong storm system early next week... A lead shortwave will move across the Great Lakes on Thursday night, with the associated surface system dragging a moisture starved cold frontal boundary through the region. A secondary shortwave will quickly move across the Ohio Valley on Friday as overall trough envelopes the eastern CONUS. Friday looks to be the best setup for some snow showers across the area as enough deep moisture combines with steep low and mid level lapse rates, and an upslope surface component. Soundings for this time period do show some convective instability with saturation well into the -10 -20 C range across northern portions of the CWA. Surface temperatures may squeak into the mid and upper 30s on Friday, however thermal profile will be easily cold enough for all snow showers below 40 degrees, some of which could produce bursts of heavy snow and gusty winds. At this point, best location for snow looks to be across southern Indiana and north central Kentucky. As was mentioned in the previous forecast, these snow showers have the potential to cause an impact across the region with very light but quick accumulations. This setup will have to be monitored. We should see a lull in the activity on Friday night with subsidence behind the quickly departing shortwave. Temperatures will be much cooler with lows dropping into the mid 20s. By Saturday, confidence is low as to exact placement of trough axis. Models are still having trouble with the timing/placement of individual waves and the overall progression of the east CONUS trough amplification. Have continued the trend of a drier Saturday as a GFS/GEM/GFS ensemble mean consensus agree on an eastern solution with subsidence aloft already in place across the Ohio Valley on Saturday. The less consistent ECMWF still holds the axis to the west. Will only mention a slight chance of a snow shower east of I-65 to account for this. May be able to go completely dry for Saturday with the next set of model runs. Temperatures will be cooler than Friday with highs only topping out in the low and mid 30s. Saturday night/Sunday morning will be the coldest of the period as lows drop to around 20. Radiational cooling conditions will not be optimal as surface winds stay up a bit and some upper level clouds look to stream overhead. Therefore, cannot drop low too near dew points that will be in the lower teens. May be able to decouple a few of the coolest spots into the upper teens but the upper level cloud cover should mostly mitigate this. Saturday night through most of Monday should be dry as surface high pressure holds over the area and weak upper level ridging holds. Sunday will begin the warming trend with highs warming into the mid 30s to low 40s. Highs on Monday will be much milder with a return of southerly flow. The mercury should rebound to the low 50s in most spots. By Monday afternoon we will begin to focus on the next storm system that looks to impact the area through Tuesday. This system will develop as a lee surface low intensifies ahead of a digging trough over the central Plains. At this point the low looks to move from the southern Plains, northeastward either into the Ohio Valley or just north to the lower Great Lakes through Tuesday morning. This warmer solution would bring overrunning rain showers to the area late Monday afternoon, with more widespread rain moving into the area Monday night and early Tuesday. Temperatures will likely crash quickly behind the system on Tuesday afternoon as sharp trough moves through and may eventually have to mention rain changing to snow. Will stick with all rain for now as it is too early to mention these details, especially with the low track in question. Will also leave any thunder mention out of the forecast with the bulk of the precipitation as any moisture return/instability would be limited by short duration of southerly flow. This system will have to be watched however, as a more northerly solution or deeper sfc low would change the instability picture. Also, chose to disregard the more southern solution offered by the operational ECMWF. This seems to be the outlier, with a general consensus between the GFS/GEM/GFS ensemble mean/ECMWF ensemble mean of a northern solution. && .Aviation (06Z TAF Issuance)... Issued at 1215 AM EST Wed Feb 13 2013 An upper level trough will pass through the area today with a sfc low pressure passing to our south. Precipitation associated with this weather system has already begun to spread northward into south central KY early this morning. Although it`s having problems overcoming a significant dry layer, we are finally getting some reports of rain in western KY and northern TN. With decent radar returns over BWG as of 5Z, will go ahead and start this TAF with VCSH. As moisture spreads northward through the early morning hours, we`ll see rains move into BWG around 8Z...LEX around 10Z...and SDF around 11Z respectively. By late morning, good forcing will enter the region causing steady moderate banded precip over the region. It`s hard to say whether a moderate band will affect the TAF sites, but at least feel confident enough to include lower MVFR conditions from mid morning through early afternoon as the heavier precip moves through the region. Some IFR cigs may be possible in some of the heavier bands of precip but will not include in the TAF at this time as confidence is low. Rain is expected to be the predominant precip type for SDF/BWG, however, LEX could see a RASN mix in a moderate band. A RASN mix isn`t out of the realm of possibilities for SDF/BWG either, but seems most likely at LEX at this time. Will need to adjust as the precip bands set up this morning and move closer to our area. By mid to late afternoon, precip should move east of the TAF sites with conditions returning to high end MVFR and then VFR by this evening. Winds will be light and variable early this morning and then become predominantly NNE as the weather system approaches our area just before sunrise. Winds will strengthen throughout the day likely exceeding 7kt this afternoon. Winds will shift to the WNW behind this system by this evening. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Short Term.......AMS Long Term........BJS Aviation.........AMS
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1250 AM EST WED FEB 13 2013 .SYNOPSIS... ISSUED AT 415 PM EST TUE FEB 12 2013 WEAK HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT LAKES TONIGHT AND WEDNESDAY. THIS PATTERN WILL GENERATE ABOVE NORMAL TEMPERATURES AND OCCASIONAL FLURRIES...ACROSS THE NORTHERN MICHIGAN INTO THURSDAY. HOWEVER...THE NEXT SYSTEM TO INFLUENCE THE GREAT LAKES ARRIVES THURSDAY...BEFORE QUICKLY LIFTING NORTHEAST INTO QUEBEC FRIDAY. THIS SYSTEM WILL GENERATE ANOTHER ROUND OF SNOW ACROSS NORTHERN MICHIGAN THURSDAY...WHILE ALSO USHERING IN MUCH COLDER CONDITIONS FRIDAY AND INTO THE WEEKEND. ACCUMULATING LAKE EFFECT SNOW CAN BE EXPECTED OVER THE WESTERN GREAT LAKES THIS WEEKEND. && .UPDATE... ISSUED AT 1234 AM EST WED FEB 13 2013 LOW LEVEL STRATO CU LIKELY TO HANG ON THROUGH THE BALANCE OF THE NIGHT WITH SHALLOW 925MB INSTABILITY HOLDS THROUGH 12Z...AND DUE TO A NARROW CORRIDOR OF MID LEVEL MOISTURE SWEEPING OVERHEAD TO GIVE IT A FIGHTING CHANCE. SOME BREAKS EXPECTED OUT THERE HOWEVER...MAINLY GTV BAY AREA AND NE LOWER TOWARD DAYBREAK. QUIET NIGHT. ALTHOUGH RELATIVELY INSIGNIFICANT...GOING AGAINST MODEL SUGGESTIONS OF FLURRIES RE-FIRING IN WSW FLOW REGIMES AS SAID MOISTURE SWEEPS IN OVERHEAD. UPDATE ISSUED AT 930 PM EST TUE FEB 12 2013 FLURRIES HAVE TEMPORARILY ENDED ACROSS NW LWR MICHIGAN LATE THIS EVENING THANKS TO BUILDING SUBSIDENCE AND SHALLOWING OF THE LOW LEVEL MOIST LAYER. LATEST IR SATELLITE DOES SHOW A LINE OF COOLER CLOUD TOPS OVER CENTRAL UPR MICHIGAN ASSOCIATED WITH A WEAK VORT LOBE AND A NARROW BAND OF MID LEVEL MOISTURE. EXPECT THESE FEATURES WILL LEND TO REDEVELOPMENT OF ADDITIONAL LAKE EFFECT FLURRIES OVERNIGHT FOR FAR NRN AND NW LWR MICHIGAN AS WELL AS PORTIONS OF ERN UPR MICHIGAN...STILL UNDER THE DIRECTION OF SW LOW LEVEL FLOW. TEMPS CONTINUE TO FALL THRU THE 20S...ON THEIR WAY TO THE UPPER TEENS AND LOWER 20S FOR OVERNIGHT LOWS. UPDATE ISSUED AT 645 PM EST TUE FEB 12 2013 LAKE EFFECT FLURRIES CONTINUE TO STREAM INTO FAR NRN AND NW LWR MICHIGAN THIS EVENING UNDER THE DIRECTION OF LOW LEVEL SW FLOW. LOW CLOUDS REMAIN TRAPPED BELOW THE SUBSIDENCE INVERSION... MAINTAINING OVC SKIES ACROSS OUR ENTIRE CWA EVEN AWAY FROM ANY LAKE INFLUENCES. VERY LITTLE WILL CHANGE THRU THE NIGHT AS LOW LEVEL MOISTURE/CLOUDS REMAINS STUCK BELOW THE INVERSION AND SW FLOW CONTINUES TO PRODUCE FLURRIES FOR FAR NRN AND NW LWR MICHIGAN. OVERNIGHT LOWS IN THE UPPER TEENS TO LOWER 20S LOOKS REASONABLE GIVEN CURRENT SURFACE DWPTS IN THAT VCNTY. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 415 PM EST TUE FEB 12 2013 COLD AIR ADVECTION HAS ABOUT MAXED OUT BEHIND YESTERDAY`S DEPARTING STORM...WITH LATEST HIGH RES RUC ANALYSIS PLACING CIRCA -11C H85 TEMPERATURES ACROSS THE NORTH WOODS. DESPITE EXCEEDINGLY LOW INVERSIONS (H85 PER SAME RUC ANALYSIS)...MOISTURE DEPTH EXTENDING TO THE LOW END OF THE FAVORED DGZ CONTINUES TO KICK OFF WIDESPREAD FLURRIES IN FAVORED WEST FLOW LAKE AREAS. ABUNDANT LOW LEVEL MOISTURE ALSO LEADING TO A MAINLY CLOUDY DAY...WITH ANY SUBSTANTIAL CLEARING OF NOTE BACK ACROSS WISCONSIN. THIS CLEARING APPEARS TIED TO DOWNWARD FORCING ON BACKSIDE OF RATHER COMPACT SHORTWAVE PINWHEELING EAST INTO NORTHERN LAKE MICHIGAN. NO SIGNIFICANT CONCERNS THROUGH THE SHORT TERM (WEDNESDAY)...ALTHOUGH LINGERING FLURRIES AND CLOUD TRENDS WILL NEED ADDRESSING. WISCONSIN SHORTWAVE WILL STEADILY AND RAPIDLY PUSH ACROSS THE AREA THIS EVENING...AND LACK OF ANY APPRECIABLE MOISTURE SHOULD PRECLUDE MUCH...IF ANY...LAKE OR SYNOPTIC RESPONSE. H85 TEMPERATURES SLOWLY WARM IN DEVELOPING WEAK SOUTHWEST FLOW WAA REGIME...REACHING THE NEGATIVE SINGLE DIGITS BY MORNING. NAM-WRF BUFFER SOUNDINGS SHOW LOW LEVEL MOISTURE FALLING BELOW -10C ISOTHERM...WHICH COMBINED WITH LOWERING DELTA T/S...WOULD SUPPORT A QUICK DEMISE TO ONGOING FLURRIES. NOT WILLING TO BITE ON THIS JUST YET...AND PREFER TO KEEP FLURRIES IN THE FORECAST...SIMPLY FOLLOWING THE WINDS FOR THERE PLACEMENT (WHICH SUGGESTS THEY SHOULD CONFINE THEMSELVES IN FAVORED SOUTHWEST FLOW AREAS THROUGH THE NIGHT). CLOUD COVER REMAINS A FORMIDABLE CHALLENGE...ESPECIALLY GIVEN WHAT IS OCCURRING BEHIND UPSTREAM WAVE. DO HAVE SOME TREPIDATION GOING TOO AGGRESSIVE WITH CLOUDS OVERNIGHT...ESPECIALLY IN NON-FAVORED LAKE AREAS. SUBTLE WARM ADVECTION AND POST-WAVE DOWNWARD RESPONSE JUST MAY WORK IN TANDEM TO FORCE MUCH MORE CLEARING THAN THIS FORECAST WILL SUGGEST. WILL TREND PARTLY CLOUDY ACROSS EASTERN UPPER AND NORTHEAST LOWER AS A STARTING POINT...WITH KNOWLEDGE THAT COMPLETELY CLOUDY OR CLEAR IS THE MORE LIKELY OUTCOME. TEMPERATURES...OF COURSE...HIGHLY DEPENDENT ON HOW THIS WHOLE CLOUD THING UNFOLDS. MID AND UPPER TEENS MAY BE SEVERAL DEGREES TOO "WARM". WE SHALL SEE. SAME STORY HEADING INTO WEDNESDAY...WITH SOME LINGERING FLURRIES AND MOSTLY TO PARTLY CLOUDY SKIES. LOW LEVEL MODIFICATION CONTINUES...SUGGESTING HIGHS IN THE LOWER AND MIDDLE 30S. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 415 PM EST TUE FEB 12 2013 MAIN FORECAST CONCERNS WILL BE POTENTIAL FOR ACCUMULATING LAKE ENHANCED SNOWS STARTING THURSDAY AND CONTINUING INTO THE WEEKEND. THE LATEST HEMISPHERIC ANALYSIS SHOWS A STABLE 3-WAVE PATTERN WITH LARGE SCALE TROUGHING OVER CENTERED OVER JAMES BAY...EAST ASIA /AROUND 120E/ AND CENTRAL EUROPE. A VERY STRONG ZONAL JET REMAINS OVER EAST ASIA AND THE WESTERN PACIFIC...WITH A SLIT FLOW OVER THE EASTERN PACIFIC EXTENDING INTO THE WEST COAST. THE SPLIT FLOW MERGES TO FORM A FASTER JET THE SOUTHEASTERN U.S. THURSDAY...AN AMPLIFYING PATTERN IS EXPECTED WITH STRONG PACIFIC JET TO BEEF UP THE WEST COAST RIDGE...RESULTING IN INCREASED TROUGHING OVER THE EASTERN TWO THIRDS OF THE CONUS BY THURSDAY. SHORT WAVE ENERGY IS EXPECTED TO ROUND THE TOP OF THE RIDGE ON WEDNESDAY...BEFORE DIVING INTO THE GREAT LAKES BY THURSDAY. AN ASSOCIATED SURFACE RESPONSE/CLIPPER SYSTEM WILL MOVE THOUGH THE GREAT LAKES...BRINGING NORTHERN MICHIGAN THE NEXT CHANCE OF SOME LIGHT SNOW. THE AMOUNT OF MOISTURE THIS SYSTEM HAS TO WORK WITH IS NOT TERRIBLE...WITH MODEL SOUNDINGS SHOWING P-WATS OF AROUND 0.3 TO 0.4 INCHES ACROSS THE CWA. THE DEGREE OF FORCING REMAINS IN SOME QUESTION...WITH TWO DISTINCT AREAS OF ENHANCED PVA EXPECTED TO MOVE THROUGH THE REGION EMBEDDED IN THE SHEARED PIECE OF ENERGY. THE NAM/GFS WANT TO SPIN UP A STRONGER LOW WITH THIS FEATURE...WHILE THE ECMWF/GEM KEEP THE SURFACE LOW MORE BENIGN. PREFER THE LATTER OF THE SOLUTIONS...GIVEN THAT THESE TWO PIECES OF ENERGY DO NOT NECESSARILY PHASE TOGETHER. OVERALL LOOKING LIKE A 1 TO 2..PERHAPS LOCALLY 3 INCH SNOW EVENT. RAPIDLY CHANGING FLOW AND WARMISH AIR ALOFT WITH H85 TEMPS BETWEEN -5 TO -8C LOOK TO KEEP A MAJOR DAMPER OF ANY LAKE ENHANCEMENT. SNOW MAY BE ALSO BE SLOW TO ACCUMULATE ON ROAD SURFACES WITH SURFACE TEMPS AT OR SLIGHTLY ABOVE FREEZING...WITH THE MORE AGGRESSIVE NAM/GFS SUGGESTING HIGHS IN THE MID TO UPPER 30S FOR THURSDAY. THIS WOULD HAVE RAIN/SNOW MIX IMPLICATIONS FOR THE LOWER ELEVATIONS OF THE CWA...BUT PREFER THE MORE COOLER...LESS AMPLIFIED SOLUTIONS FOR NOW. THURSDAY NIGHT AND FRIDAY...FORCING BEGINS TO PUSH EAST OF THE AREA BY LATE THURSDAY AFTERNOON WITH STRONG COLD AIR ADVECTION ENSUING ACROSS THE CWA THURSDAY NIGHT INTO FRIDAY. THIS WILL RAMP UP THE LAKE EFFECT SNOW MACHINE DURING THIS TIMEFRAME. MODELS ARE NOT IN THE BEST AGREEMENT WITH THE NAM/GFS MORE NORTHWESTERLY THAN THE NNW FLOW DEPICTED BY THE ECMWF. MODEST INVERSION HEIGHTS AND DEEPEST MOISTURE MOVING OUT SHOULD KEEP MAJOR LAKE SNOW ACCUMULATIONS IN CHECK...HOWEVER SEVERAL INCHES OF ACCUMULATION LOOK LIKELY FOR THE NW/NNW FAVORED SNOW BELTS THROUGH FRIDAY. H85 TEMPS FALL TO -15 TO -18C DURING THE DAY FRIDAY...WITH MODEL CONSENSUS SHOWING HIGHS STRUGGLING TO MAKE IT OUT OF THE TEENS. FRIDAY NIGHT THROUGH TUESDAY...CHILLY CONDITIONS ENSUE AS DEEP TROUGH SETTLES INTO THE GREAT LAKES WITH MODEL CONSENSUS SHOWING H85 TEMPS IN THE -18 TO -22 RANGE ACROSS THE GREAT LAKES INTO THE DAY ON SATURDAY. CERTAINLY PLENTY OF INSTABILITY TO KEEP THE LAKE EFFECT SNOW MACHINE GOING...WITH POCKETS OF DEEPER H85-H7 MOISTURE ASSOCIATED WITH EMBEDDED SHORTWAVES ROUNDING THE LONGER WAVE TROUGH AND CONTINUED NORTHWEST TO NORTH NORTHWEST FLOW. AT THE LEAST...SEVERAL INCHES OF ACCUMULATION LOOK LIKELY IN THE NW TO NNW FAVORED SNOW BELTS WITH THIS PATTERN. LOOKING AT SOME OF COOP SNOWFALL GUIDANCE FROM THE CIPS ANALOGS FOR THE 72 HOUR PERIOD CENTERED ON 00Z/17 SHOWS HEAVY ACCUMULATIONS FOR 3 OF THE TO 5 ANALOGS. STILL PLENTY OF DETAILS TO WORK OUT BETWEEN NOW AND THIS WEEKEND...WITH ICE COVER OVER NORTHERN LAKE MICHIGAN AND MODEST INVERSION HEIGHTS SERVING AS MITIGATING FACTORS FOR HEAVY ACCUMULATIONS. STILL COULD SEE THE POSSIBILITY OF SOME HEADLINES FOR THE FRI/SAT TIMEFRAME...AND WILL MAINTAIN THE THREAT FOR ACCUMULATING LAKE SNOWS IN THE HWO. SUNDAY THROUGH MONDAY...PROGRESSIVE PATTERN CONTINUES WITH DEEP TROUGH KICKING OFF TO THE NORTHEAST AND HEIGHTS MODIFYING SUBSTANTIALLY AS UPSTREAM RIDGING BUILDS INTO THE GREAT LAKES. 1000-850 MEAN FLOW IS PROGGED TO BACK TO THE SOUTHWEST WITH H85 TEMPS MODIFYING ENOUGH TO END THE LES THREAT...ALTHOUGH THERE MAY BE SOME LINGER -SHSN FOR SW FAVORED FLOW AREAS INITIALLY SUNDAY MORNING. ANOTHER CLIPPER SYSTEM LOOKS TO TRAVERSE THE AREA SUNDAY NIGHT INTO MONDAY...HOWEVER THE BETTER MOISTURE AND FORCING LOOK TO REMAIN OVER THE NORTHERN PORTION OF THE CWA ATTM. MONDAY NIGHT INTO TUESDAY...NEXT TROUGH BUILDS INTO THE GREAT LAKES WITH GFS/ECMWF DEPICTING A STORM SYSTEM DEVELOPING IN THE SOUTHERN PLAINS AND MOVING UP THROUGH THE OHIO VALLEY INTO THE GREAT LAKES. NOT A LOT OF CONFIDENCE OF COURSE THIS FAR OUT...ESPECIALLY WHEN LOOKING AT SOME OF THE ENSEMBLE GUIDANCE ON THE UPPER AIR PATTERN...BUT SOME SIGNALS ARE THERE OF SAID SYSTEM WHEN LOOKING AT THE REANALYSIS BASED ON THE TOP GFS/CAN ENS TOP ANALOGS. SOMETHING THAT WILL CERTAINLY NEED TO BE MONITORED. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1234 AM EST WED FEB 13 2013 MVFR CIGS LIKELY TO HANG ON THROUGH MUCH OF THE NIGHT...AND EVEN INTO A FEW HOURS AFTER DAYBREAK. THIS AIDED BY SHALLOW OVERLAKE INSTABILITY AND WEAK DISTURBANCE/CORRIDOR OF MID LEVEL MOISTURE ALOFT SWEEPING THROUGH. DO BELIEVE THE MVFR CIGS WILL MIX OUT...ALTHOUGH WINDS/MIXING NOT SO IMPRESSIVE HEADING INTO TOMORROW. WILL GO VFR WITH BROKEN MID/HIGH CLOUD AROUND FOR MUCH OF THE DAY AND INTO THE EVENING. AN ALBERTA CLIPPER ARRIVES LATE TOMORROW NIGHT...BRINGING POSSIBLE SNOWS AND MVFR CIGS BACK INTO NW LOWER AFTER THE TAF PERIOD. WINDS WILL BE RELATIVELY LIGHT OUT OF THE SW. && .MARINE... ISSUED AT 415 PM EST TUE FEB 12 2013 MARINE...VEERING WINDS TO SOUTHWEST REMAIN SOMEWHAT GUSTY HEADING INTO THIS EVENING. MAY EVEN SEE SOME SCA PRODUCING GUSTS ALONG THE NORTHWEST LOWER LAKE MICHIGAN COAST...ALTHOUGH DURATION DOES NOT SUPPORT A SPECIFIC SCA HEADLINE. SOUTHWEST AND SUB-ADVISORY WINDS TO CONTINUE THROUGH THURSDAY MORNING. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...SD SYNOPSIS...SR SHORT TERM...MB LONG TERM...NS AVIATION...SD MARINE...MB
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
443 AM EST WED FEB 13 2013 .SYNOPSIS... LOW PRESSURE OVER ALABAMA WILL TRACK NORTHEAST INTO VIRGINIA THIS AFTERNOON...THEN OFF THE EAST COAST TONIGHT. THIS SYSTEM EXITS THURSDAY MORNING. ANOTHER LOW CROSSING THROUGH THE GREAT LAKES WILL PUSH A COLD FRONT THROUGH THE REGION ON FRIDAY AND SATURDAY. HIGH PRESSURE WILL BE OVER THE AREA ON SUNDAY AND MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 430 AM EST WEDNESDAY... PERSISTENT BAND OF RAIN OVER THE SOUTHERN COUNTY WARNING AREA WAS ORIENTED ALONG AND WELL NORTH OF THE WARM FRONT. DON`T EXPECT MUCH EXPANSION OF THE AREAL COVERAGE OF PRECIPITATION UNTIL THE UPPER LOW GETS CLOSER. LOCAL WRF FROM 00Z ALONG WITH RAP MODELS AND BUFKIT HAVE MORE WIDESPREAD PRECIPITATION ARRIVING IN THE WESTERN COUNTY WARNING AREA AROUND 7AM AND REACHING EASTERN COUNTIES BEFORE NOON. DURING THE DAY THE SURFACE LOW MOVES FROM ALABAMA THIS MORNING INTO SOUTHWEST VIRGINIA THIS AFTERNOON. FORECAST AREA STAYS NORTH OF THE WARM FRONT. EXPECT ENOUGH EAST TO SOUTHEAST SURFACE AND LOW LEVEL WINDS TO ENHANCE THE PRECIPITATION AMOUNTS ON EASTERN SLOPES THROUGH 00Z/7PM TONIGHT. BEST SYNOPTIC LIFT ARRIVES WITH THE UPPER LOW. MODELS MORE IN LINE WITH TEMPERATURE PROFILE TODAY AND TONIGHT. MAINLY USED A NAM/RAP BLEND FOR TEMPERATURES AND PRECIPITATION TYPE...WHICH WAS SLIGHTLY COOLER THAN THE GFS. EVEN THE COOLER GUIDANCE LIMITED ANY WINTER PRECIPITATION TO THE VERY HIGHEST ELEVATIONS FROM NORTHWEST NORTH CAROLINA INTO TAZEWELL COUNTY...AND FROM MERCER COUNTY INTO BATH COUNTY. THE COMBINATION OF STRATIFORM SNOWFALL FROM THE UPPER LOW TODAY AND UPSLOPE SNOW SHOWERS THIS EVENING STILL SUPPORTS SNOW ACCUMULATIONS THAT REACH ADVISORY CRITERIA ONLY IN GREENBRIER COUNTY. SO NO CHANGES TO THE ADVISORY NEEDED AT THIS TIME. STAYED COOLER THAN GUIDANCE FOR BOTH HOURLY TEMPERATURES AND MAXIMUM TEMPERATURES FOR TODAY. MORE TYPICAL DIURNAL/COLD AIR ADVECTION TREND EXPECTED FOR TONIGHT. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... AS OF 400 AM EST WEDNESDAY... BY SUNRISE THURSDAY...EXPECT TO SEE SNOW SHOWER ACTIVITY ACROSS THE MOUNTAINS COMING TO AN END AND WIND SPEEDS DIMINISHING AS HIGH PRESSURE...BUILDING IN FROM THE GULF COAST REGION...BECOMES THE DOMINANT FEATURE OF THE MOMENT IN OUR PROGRESSIVE WEATHER PATTERN. RELATIVELY ZONAL FLOW ALOFT WILL HELP MAINTAIN MILD TEMPERATURES... AND EXPECT AFTERNOON HIGHS TO RANGE FROM THE MID TO UPPER 40S ACROSS THE MOUNTAINS...TO THE MID 50S ACROSS THE PIEDMONTS. COME EARLY FRIDAY AFTERNOON HOWEVER...WE CAN EXPECT ANOTHER STRONG COLD FRONT TO MOVE ACROSS THE AREA...USHERING IN A SHOT OF ARCTIC AIR. WITH THE ARRIVAL OF THE COLD FRONT...WILL ALSO SEE ANOTHER ROUND OF SNOW SHOWERS DEVELOP ACROSS THE MOUNTAINS...WITH THE HIGHEST SNOWFALL AMOUNTS OCCURRING IN THE USUAL NORTHWEST WIND UPSLOPE AREAS. WINDS WILL ALSO BE ON THE GUSTY SIDE THROUGH THE DAY THANKS TO A 5MB TO 6MB PRESSURE GRADIENT ACROSS THE AREA BETWEEN LOW PRESSURE OVER EASTERN CANADA...AND HIGH PRESSURE BUILDING ACROSS THE PLAINS. GUSTY WINDS WILL CONTINUE THROUGH FRIDAY NIGHT AND EARLY SATURDAY MORNING...CAUSING WIND CHILL TEMPERATURES TO RANGE FROM THE POSITIVE SINGLE DIGITS IN SOUTHEAST WEST VIRGINIA...TO THE 20S ACROSS THE PIEDMONTS. MOUNTAIN SNOW SHOWER ACTIVITY WILL CONTINUE ON SATURDAY...AND BELIEVE THAT PORTIONS OF OUR FORECAST AREA FROM THE NORTH CAROLINA MOUNTAINS THROUGH THE ALLEGHANY HIGHLANDS WILL HAVE A HARD TIME RISING ABOVE FREEZING FOR DAYTIME HIGHS THANKS TO A DEEP UPPER LEVEL TROUGH BUILDING SOUTHWARD FROM EASTERN CANADA THROUGH THE GULF COAST. THE TROUGH REMAINS PROGRESSIVE HOWEVER...AND WILL CONTINUE AN EASTWARD JOG THROUGH SATURDAY NIGHT...EVENTUALLY PUSHING OFF THE ATLANTIC COAST BY SUNDAY MORNING. && .LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 400AM EST WEDNESDAY... A PATTERN CHANGE TO RIDGING IN THE EAST STILL LOOKS PROMISING AS WE HEAD INTO EARLY NEXT WEEK. TEMPERATURES WILL START TO TREND MILDER...AND PRECIPITATION WILL START TO ENTER THE REGION MONDAY NIGHT IN THE WEST AS SOUTHERLY WINDS START TO ADVECT MOISTURE FROM THE GULF IN ADVANCE OF OUR NEXT APPROACHING TROUGH. A COLD FRONT IS EXPECTED TO BE ON OUR WESTERN DOORSTEP BY LATE TUESDAY AFTERNOON. EXPECT INCREASING CHANCE OF SHOWERS THROUGH THE DAY...THE THE BEST COVERAGE IN THE WEST. THE CHANCES OF A GUSTY DAY LOOK PROMISING AS FORECAST 850 MB WINDS AHEAD OF THE FRONT ARE IN THE 60 TO 70 KT RANGE. WHILE GUIDANCE DOES NOT INDICATE WE WILL HAVE MUCH IN THE WAY OF INSTABILITY...LOW LEVEL SHEAR WILL LIKELY BE HIGH. && .AVIATION /10Z WEDNESDAY THROUGH SUNDAY/... AS OF 100 AM EST WEDNESDAY... RADAR IMAGERY INDICATES THAT THE FIRST ROUND OF PRECIPITATION HAS PASSED THE AREA THIS MORNING...REMAINING CONFINED MAINLY TO NORTH CAROLINA AND EXTREME SOUTHERN VIRGINIA...AND PASSING ACROSS DAN. CURRENTLY LOOKING AT MAINLY VFR CEILINGS...BUT EXPECT THAT TO CHANGE BEFORE SUNRISE AS AN APPROACHING UPPER TROUGH...AND ASSOCIATED SURFACE LOW...MOVES INTO THE AREA. LOW END MVFR AND IFR CEILINGS WILL DEVELOP DURING THE 09Z TO 12Z TIME FRAME AS SOUTHEASTERLY WIND FLOW ACROSS THE AREA INCREASES. PRECIPITATION... MAINLY IN THE FORM OF RAIN MIXED OCCASIONALLY WITH SLEET OR SNOW...WILL BECOME WIDESPREAD THROUGH THE DAY AS THE LOW PASSES THE AREA DURING THE AFTERNOON. AS THE LOW MOVES TO THE COAST DURING THE EVENING...WINDS WILL SHIFT NORTHWESTERLY...BRINGING COLDER AIR INTO THE AREA AND CAUSING RAIN TO CHANGE TO SNOW SHOWERS. WILL LIKELY BE LOOKING A BRIEF PERIOD OF SNOW FOR ROA...DAN AND LYH BEFORE MOISTURE MOVES OUT OF THE AREA...HOWEVER SNOW SHOWERS WILL LINGER THROUGH THE NIGHT FURTHER TO THE WEST. EXPECT SNOW SHOWERS TO END AT ALL AIRPORTS BY SUNRISE THURSDAY. WILL ALSO EXPERIENCE GUSTY WINDS THROUGH THE NIGHT THANKS TO A TIGHT PRESSURE GRADIENT BETWEEN THE DEPARTING LOW AND APPROACHING HIGH PRESSURE. AN ARCTIC COLD FRONT IS EXPECTED TO CROSS THE REGION FRIDAY NIGHT WITH GUSTY WINDS...AND PERHAPS A PERIOD OF MOUNTAIN MVFR CIGS INCLUDING SNOW OR SNOW SHOWERS INTO SATURDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR WVZ045. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...NF LONG TERM...DS AVIATION...DS/NF/WP
AREA FORECAST DISCUSSION
NWS EUREKA CA
358 AM PST WED FEB 13 2013 .SYNOPSIS... A STRONG AND PERSISTENT RIDGE OF HIGH PRESSURE WILL KEEP NORTHWEST CALIFORNIA DRY THROUGH AT LEAST SATURDAY MORNING. WHILE MORNING CLOUDS ALONG THE NORTH COAST WILL GIVE WAY TO SUNSHINE THERE WILL STILL BE A COOL BREEZE THIS AFTERNOON. INTERIOR AREAS WILL STAY SUNNY OUTSIDE OF AREAS OF VALLEY FOG. OFFSHORE FLOW WILL BRING WARMER CONDITIONS TO THE COAST LATER THURSDAY AND FRIDAY. && .SHORT TERM... STRATUS IS MUCH MORE WELL-ESTABLISHED ALONG THE COAST BETWEEN CAPE MENDOCINO AND TRINIDAD EARLY THIS MORNING. WITH UPPER RIDGING BUILDING OVER THE EASTERN PACIFIC SFC HIGH PRESSURE HAS STRENGTHENED...RESULTING IN AN INCREASED ONSHORE GRADIENT ALONG THE IMMEDIATE COAST. RUC ANALYSIS SHOWS THE THERMAL TROUGH TO BE A BIT WEAKER AND ORIENTED FURTHER INLAND...ALLOWING THE NORTHERLY FLOW TO RETURN TO THE MENDOCINO COAST AND KEEP ANY STRATUS WELL TO THE SOUTH OR FURTHER OFFSHORE. MEANWHILE ENOUGH OFFSHORE FLOW STILL EXISTS CLOSER TO THE SFC RIDGE AXIS IN SOUTHERN OREGON TO KEEP CRESCENT CITY MOSTLY CLEAR. EXPECT THE STRATUS TO ERODE THIS AFTERNOON AS BOUNDARY LAYER NORTHERLY WINDS INCREASE. EXPECT SIMILAR CONDITIONS TONIGHT WITH EVEN MORE BOUNDARY LAYER MOISTURE AND A STRONGER INVERSION AS THE RIDGE PUSHES CLOSER TO THE WEST COAST. UPPER LEVEL RIDGING WILL CONTINUE TO PUSH EASTWARD TOWARD THE WEST COAST ON THURSDAY AND THE RIDGE AXIS WILL PASS BY FRIDAY MORNING. THIS WILL ALLOW HIGH PRESSURE BOTH AT THE SFC AND ALOFT TO BUILD OVER THE PACIFIC NORTHWEST AND EVENTUALLY THE GREAT BASIN...WHILE THE THERMAL TROUGH PUSHES WESTWARD OFF THE COAST. INCREASING OFFSHORE FLOW WILL RESULT LATER THURSDAY INTO FRIDAY WITH CLEAR SKIES AND LIGHT WINDS ACCOMPANIED BY ABOVE NORMAL TEMPERATURES. EVEN THE IMMEDIATE COAST WILL REACH 60 DEGREES WITH 70S ACROSS THE INTERIOR VALLEYS. AAD .LONG TERM... BY SATURDAY AFTERNOON ONSHORE FLOW WILL RETURN WITH BOUNDARY LAYER MOISTURE INCREASING AGAIN AT THE COAST. TEMPERATURES WILL BEGIN TO COOL WITH INCREASING CLOUD COVER...ALONG WITH A SLIGHT CHANCE OF SHOWERS. MODELS DO NOT SHOW ANY MEASURABLE RAINFALL SOUTH OF THE OREGON BORDER AS MOISTURE WILL BE VERY LIMITED. AS SUCH DO NOT EXPECT MORE THAN A SHOWER OR TWO IN THE LIMITED FORCING ALONG THE WEAKENING COLD FRONT. MAY NEED TO ADD FOG AND DRIZZLE OVERNIGHT INTO SUNDAY MORNING WITH THE ONSHORE PUSH OF BOUNDARY LAYER MOISTURE. BY SUNDAY THE AIRMASS WILL DRY OUT WITH NORTHERLY FLOW RETURNING AS HIGH PRESSURE BUILDS BACK OVER THE EASTERN PACIFIC. A MORE SIGNIFICANT SYSTEM WILL APPROACH BY MONDAY NIGHT IN THE FORM OF AN UPPER LEVEL LOW DROPPING SOUTHEASTWARD FROM THE GULF OF ALASKA. ALTHOUGH MODELS ARE SIMILAR IN THE GENERAL PATTERN NEXT WEEK THERE ARE SOME SIGNIFICANT DIFFERENCES WITH RESPECT TO THE DETAILS. HAVE OPTED TO RAISE POPS TO AROUND DOUBLE CLIMO AS THERE IS HIGH CONFIDENCE IN A PERIOD OF SHOWERS AND MOUNTAIN SNOW CENTERED AROUND TUESDAY. THAT SAID PRECIPITATION AMOUNTS AND THE DEGREE OF COLD AIR WITH THE SYSTEM ARE VERY MUCH UP IN THE AIR. AAD && .AVIATION...11-4U SAT IMAGERY SHOWS OFFSHORE FLOW RESULTING IN CLEARING STRATUS N OF TRINIDAD. PATCHY FG N OF TRINIDAD WILL RESULT IN MVFR VSBYS/IFR CIGS THROUGH 17Z. GREATER ONSHORE COMPONENT S OF TRINIDAD WILL RESULT IN IFR TO MVFR CIGS AROUND HUMBOLDT BAY AND THE EEL RIVER VALLEY INTO NRN MENDO COUNTY THROUGH 20Z. VFR CONDITIONS WILL PERSIST THROUGH THE AFTERNOON THEN DETERIORATE THIS EVENING. STRATUS/FG WILL IMPACT AREAS AROUND HUMBOLDT BAY AS EARLY AS 14/00Z WITH IFR CONDITIONS EXPANDING ALONG THE COAST AND INLAND OVERNIGHT. && .MARINE...BUOY OBS SHOW NLY WINDS REMAINING AROUND 20 KT N OF CAPE MENDO WITH SEAS AROUND 10 FT. WINDS WILL INCREASE AGAIN THIS AFTERNOON THEN DECREASE LATE THU. LONG PERIOD WAVE GROUP WILL CONTINUE TO DECAY THIS MORNING WITH FORERUNNERS FROM ANOTHER WAVE GROUP BUILDING INTO THE WATERS THIS AFTERNOON/EVENING. A 3RD WAVE TRAIN WILL ARRIVE LATE FRI/EARLY SAT AND PERSIST THROUGH THE WEEKEND. && .EKA WATCHES/WARNINGS/ADVISORIES... CA...NONE. NORTHWEST CALIFORNIA COASTAL WATERS... SMALL CRAFT ADVISORY UNTIL 9 PM PST THURSDAY PZZ450. SMALL CRAFT ADVISORY UNTIL 9 AM PST FRIDAY PZZ470. SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 3 PM PST THURSDAY PZZ455. SMALL CRAFT ADVISORY UNTIL 3 AM PST FRIDAY PZZ475. && $$ VISIT US AT HTTP://WWW.WEATHER.GOV/EUREKA FOLLOW US ON FACEBOOK AND TWITTER AT: HTTP://WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.EUREKA.GOV HTTP://WWW.TWITTER.COM/NWSEUREKA
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1041 AM EST WED FEB 13 2013 .SYNOPSIS... LOW PRESSURE WILL BE LIFTING NORTHEAST OF THE FORECAST AREA THIS AFTERNOON AND TONIGHT. WEAK HIGH PRESSURE WILL DOMINATE THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... LOW PRESSURE CENTERED NEAR THE FORECAST AREA WAS SUPPORTING AREAS OF LIGHT RAIN AND DRIZZLE. LATER TODAY...THE LOW WILL BE FARTHER NORTH OF THE AREA AND ISENTROPIC DOWNGLIDE WILL BECOME DOMINATE. THE RAIN CHANCE SHOULD DECREASE. THE NAM AND GFS INDICATED H85 WINDS OF 40 TO 50 KNOTS AND THE KCAE 88D HAS VERIFIED THESE WINDS. THE MODELS SHOWED THIS WIND CONTINUING FOR MUCH OF THE DAY...THEN DIMINISHING LATE TODAY AND TONIGHT. LINGERING CLOUDINESS SHOULD LIMIT MIXING...BUT WITH THE DRYING IN THE AFTERNOON IT SHOULD BECOME BREEZY. THE NAM MOMENTUM TRANSFER INDICATED A POTENTIAL FOR GUSTS NEAR 30 KNOTS. THE HRRR INDICATED WIND GUSTS OF 25 TO 30 KNOTS DEVELOPING IN THE SOUTH PART AROUND 100 PM...WITH GUSTS OF 30 TO 35 KNOTS OVER MUCH OF THE REMAINING AREA BEGINNING AROUND 300 PM. WE HAVE POSTED A LAKE WIND ADVISORY. MODEL TIME SECTIONS SHOW FURTHER DRYING OVERNIGHT AND EXPECT SKIES WILL BECOME CLEAR. WE USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... THE NAM AND GFS SHOW WEAK RIDGING DOMINATING THURSDAY INTO FRIDAY. A REINFORCING DRY COLD FRONT APPEARS TO CROSS THE AREA FRIDAY AFTERNOON AND EVENING. GUIDANCE AND LOCAL NUMBERS ARE VERY CLOSE THROUGH THE PERIOD. && .LONG TERM /SATURDAY THROUGH TUESDAY/... ALL OF THE MODELS SHOW A DEEP...PROGRESSIVE...TROUGH ACROSS THE EASTERN HALF OF THE COUNTRY SATURDAY. THE ECMWF AND GFS DIFFER ON THE SPEED AND STRENGTH OF ADDITIONAL UPPER-LEVEL ENERGY MOVING THROUGH THE TROUGH AND EVENTUALLY HELPING TO LIFT THE TROUGH TO THE EAST AND NORTHEAST BY SUNDAY OR MONDAY. THE GFS DEVELOPS LOW PRESSURE OFF THE MID ATLANTIC COAST SATURDAY AND IS FASTER. THE SLOWER ECMWF...DEVELOPS LOW PRESSURE OFF THE CAROLINA COAST SATURDAY NIGHT AND SUNDAY MORNING. AT THIS TIME...WILL KEEP THE FORECAST DRY FOR THE WEEKEND. THIS WILL BE FOLLOWED BY ANOTHER QUICK MOVING SYSTEM APPROACHING THE REGION TUESDAY. THE MODELS AGREE SHOWING A MOISTURE INCREASE TUESDAY ASSOCIATED WITH A COLD FRONT. THE GFS AND ECMWF MOS SUPPORT BELOW NORMAL TEMPERATURES SATURDAY THROUGH MONDAY...AND NEAR NORMAL DURING THE REST OF THE MEDIUM-RANGE PERIOD. && .AVIATION /16Z WEDNESDAY THROUGH SUNDAY/... A WARM FRONT WILL SLOWLY LIFT NORTHWARD INTO THE AREA FROM CENTRAL GEORGIA THIS MORNING. EXPECT IFR OR LIFR CEILINGS THROUGH THE REST OF THE MORNING WITH PATCHY LIGHT SHOWERS OR DRIZZLE AT TIMES. AS THE WARM FRONT LIFTS NORTH OF THE AREA CONDITIONS SHOULD IMPROVE AND AS LOW CLOUDS LIFT AFTER 17Z-20Z. DEEP MIXING WITHIN AN INCREASING PRESSURE GRADIENT/COLD FRONTAL PASSAGE FROM THE WEST...WILL RESULT IN STRONG SOUTHWEST TO WESTERLY WINDS WITH GUSTS TO 25 KNOTS. EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION EXPECTED. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR SCZ015-016- 018-020>022-025>031-035>038-041. GA...LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR GAZ040- 063>065-077. && $$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
626 AM EST WED FEB 13 2013 .PREV DISCUSSION... /ISSUED 423 AM EST WED FEB 13 2013/ SHORT TERM /TODAY THROUGH THURSDAY/... LOW PRESSURE IS CURRENTLY ACROSS NORTHERN AL AND THE ASSOCIATED COLD FRONT STRETCHES INTO THE GULF OF MEXICO. A WARM FRONT IS ALSO SITUATED ALONG THE GA/FL BORDER. REGIONAL RADAR SHOWS THE HEAVIEST PRECIP IN THE VICINITY OF A WEAK LOW PRESSURE MOVING EAST ALONG THE WARM FRONT. THE COLD FRONT WILL MOVE THROUGH THE NW HALF OF THE CWA DURING THE EARLY MORNING AND THE REMAINDER OF THE CWA BY THE EARLY AFTERNOON. MODELS HAVE BEEN AGGRESSIVE WITH MOVING THE WARM FRONT NORTHWARD...BUT THE COOLER HIGH PRESSURE WEDGE HAS HELD FIRM AND ALLOWED LITTLE NORTHWARD PROGRESSION. WITH BOUNDARY LAYER WINDS 15 TO 20 KT OUT OF THE SOUTH...DO THINK THAT THERE WILL BE A LITTLE NORTHWARD PROGRESSION OF THE WARM SECTOR THIS MORNING...THUS THE BEST INSTABILITY WILL REMAIN ACROSS THE SOUTHERN ZONES. WITH STEEP MID LEVEL LAPSE RATES AND BUFKIT SOUNDINGS SHOWING AN INVERTED V STRUCTURE...LARGE HAIL AND DAMAGING WIND GUSTS WOULD BE THE PRIMARY MODE OF SEVERE WEATHER. HOWEVER...DO THINK IF SEVERE THUNDERSTORMS DEVELOP THEY WILL BE ISOLATED IN NATURE. PRECIP CHANCES WILL DIMINISH FROM WEST TO EAST BEHIND THE COLD FRONT LATER THIS AFTERNOON. OVERNIGHT AND THURSDAY ARE EXPECTED TO REMAIN DRY AS HIGH PRESSURE BUILDS OVERHEAD. TOOK BLEND FOR MAX/MIN TEMPS. NLISTEMAA LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... GFS AND ECMWF ARE IN CLOSE AGREEMENT IN THE LONG TERM. THE EASTERN TROUGH DEEPENS AS A STRONG SHORT WAVES MOVES OUT OF CANADA AND INTO THE CENTRAL AND EASTERN U.S. THIS WILL DRIVE AN ARCTIC FRONT INTO THE CWA FRIDAY AND FRIDAY NIGHT. WITH EACH MODEL RUN THE MOISTURE IS SHOWING UP LESS AND LESS AND APPEARS THAT LITTLE IF ANY PRECIP WILL FALL FROM THIS SHORT WAVE. THE ONLY AREAS THAT COULD SEE SOME LIGHT RAIN WILL BE EXTREME NORTH GA DURING THE DAY FRIDAY. CONTINUED UPSLOPE FLOW IN THE NORTHEAST MOUNTAINS COULD YIELD A FEW SNOW SHOWERS DURING THE DAY SATURDAY. STRONG COLD ADVECTION SATURDAY COUPLED WITH 30 TO 40 KT H8 WINDS WILL YIELD WINDY CONDITIONS ON SATURDAY ACROSS THE CWA. STILL LOOKS LIKE GFS GUIDANCE IS TOO WARM ON THIS WEEKEND TEMPS AND HAVE DROPPED THEM CONSIDERABLY. THIS ARCTIC SURGE WILL BE SHORT LIVED AS THE FLOW BECOMES ZONAL BY MONDAY MORNING. THE SURFACE HIGH WILL BE TO OUR EAST WITH ANOTHER SYSTEM DEVELOPING OVER THE MIDDLE OF THE COUNTY. TEMPS WILL MODERATE BEGINNING MONDAY AFTER A COLD START. BY MONDAY EVENING/TUESDAY MOISTURE WILL RETURN TO THE CWA. MOST OF THE ENERGY APPEARS TO BE IN THE OHIO VALLEY BUT ANOTHER COLD FRONT WILL MOVE ACROSS THE CWA TUESDAY BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS. 17 && .AVIATION... 12Z UPDATE... LIFR CIGS AT THE TERMINALS THIS MORNING SHOULD CONTINUE UNTIL A W/SW WIND SHIFT OCCURS BETWEEN 15-17Z. GUSTS 20-25 KT WILL BE POSSIBLE. A COLD FRONT WILL ALSO MOVE THROUGH DURING THE LATE MORNING AND EARLY AFTERNOON. HRRR PRODUCES A BROKEN LINE OF SHOWERS ALONG THE FRONT...AND HAVE TRIED TO TIME THAT. WILL NOT REDUCE VSBSY AS PRECIP WILL REMAIN SCT IN NATURE. VFR CONDITIONS AFTER 00-002Z. //ATL CONFIDENCE...12Z UPDATE... MEDIUM CONFIDENCE ON CIGS AND VSBY. HIGH CONFIDENCE ALL OTHER ELEMENTS. NLISTEMAA && .PRELIMINARY POINT TEMPS/POPS... ATHENS 57 34 58 37 / 40 10 0 5 ATLANTA 55 36 57 40 / 40 10 0 5 BLAIRSVILLE 49 31 53 32 / 40 10 0 10 CARTERSVILLE 53 34 57 34 / 40 10 0 5 COLUMBUS 59 38 60 40 / 40 10 0 5 GAINESVILLE 54 34 55 38 / 40 10 0 5 MACON 61 38 60 36 / 40 20 0 5 ROME 53 34 57 32 / 40 10 0 10 PEACHTREE CITY 57 33 57 36 / 40 10 0 5 VIDALIA 70 43 61 41 / 40 30 0 10 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
932 AM EST WED FEB 13 2013 .UPDATE... ISSUED AT 931 AM EST WED FEB 13 2013 LIGHT...INTERMITTENT RAIN WITH TEMPS AROUND 40 COVERING MOST OF THE CWFA. LOWER TEMPS AND LIGHT SNOW TO OUR WEST. UPDATED GRIDS TO INDICATE LATE MORNING HIGH TEMPS AND THEN FALLING TEMPS THIS AFTERNOON. RAIN SHOULD CHANGE TO SNOW AND THERE MAY BE A FEW BANDS OF SNOW TO ACCUMULATE BUT THE GROUND AND ESPECIALLY THE ROADS ARE TOO WARM TO SUPPORT OTHER THAN MOMENTARY ACCUMULATIONS. BY THE TIME THE COLD AIR ARRIVES AND THE RAIN CHANGES TO ALL SNOW...MOST OF THE MOISTURE WILL BE EAST OF THE AREA AND JUST A FEW FLURRIES WILL REMAIN FOR ALL BUT THE HIGHER ELEVATIONS NEAR THE VA/W VA BORDER. UPDATED GRIDS AND ZONES WITH LATEST INFORMATION. UPDATE ISSUED AT 658 AM EST WED FEB 13 2013 CURRENT CONDITIONS ACROSS EASTERN KENTUCKY HAVE PRECIP MOVING INTO THE AREA WITH RAIN REACHING THE GROUND IN THE SOUTH. HAVE UPDATED TO FINE TUNE POPS AND ANY COOLING EFFECTS TO TEMPS FROM THE RAINFALL. UPSTREAM...IT SEEMS THE BAND SETTING UP WILL STAY JUST NORTH SO WILL KEEP CURRENT SNOWFALL FORECAST IN PLACE. ONLY CONCERN RIGHT NOW IS THE COOLING EFFECTS AND SURFACE TEMPS OVER THE SOUTH AS SOME REPORTS OF MODERATE RAIN POSSIBLY REALLY COOLING SURFACE TEMPS. WILL BANK ON SURFACE TEMPS STAYING WARM ENOUGH THROUGH THE EARLY AFTERNOON BEFORE THE COLD AIR FINALLY CHANGES THE RAIN OVER THIS AFTERNOON. ALSO...MODEL SOUNDINGS CONTINUE TO SHOW DRY AIR AIR AT THE 10 DEGREE CELSIUS TEMPS AND HIGHER SO WILL KEEP THE INCH OR SNOW FORECAST NORTH OF THE MOUNTAIN PARKWAY AND IN THE HIGHEST ELEVATIONS SO NO NEW ZFP WAS NEEDED. && .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 423 AM EST WED FEB 13 2013 CURRENT 09Z ANALYSIS ACROSS THE AREA HAS WIDESPREAD CLOUD COVER OVER EASTERN KENTUCKY WITH PRECIP ALONG THE TN AND KY BORDER IN SOUTH CENTRAL KY DEVELOPING AND MOVING INTO THE AREA. CURRENT TEMPERATURES ACROSS THE SOUTHERN PORTION OF THE AREA ARE IN THE LOW 40S TO UPPER 30S. HOWEVER SURFACE TEMPS ALONG AND NORTH OF THE MOUNTAIN PARKWAY ARE COLD ENOUGH TO SUSTAIN SOME SNOWFALL AS THE PRECIP WILL CREEP INTO THE NORTHERN PORTION OF THE CWA BY 12Z. MET SAT DATA CURRENTLY SHOWS THE DEVELOPING SURFACE LOW OVER THE LOWER TN VALLEY AND SHIFTING OFF TO THE NORTHEAST. THE UPPER LOW IS LOCATED OVER SOUTHERN IL MOVING TO THE EAST NORTHEAST. CURRENT SHORT TERM MODELS INDICATE A BAND OF HEAVY PRECIP SETTING UP. THE CHALLENGE HERE IS THE LOCATION OF THE DEVELOPMENT. BOTH THE NAM AND GFS HAVE INDICATED A BAND OF HEAVIER PRECIP JUST SOUTH OF THE OH RIVER AND ALSO ANOTHER BAND GOING THROUGH CENTRAL EASTERN KY. THE HI RES HRRR ALSO SHOWS THIS BUT WITH THE SOUTHERN BAND NOT AS INTENSE. BASED ON CURRENT WV SHOWING MID LEVEL MOISTURE AND ADVECTING TOWARD THE UPPER OH VALLEY...HAVE GONE WITH THE BLUEGRASS AND LOCATIONS NORTH OF THE MOUNTAIN PARKWAY TO RECEIVE UP TO AN INCH OF SNOWFALL. CURRENT THOUGH IS WITH THE SOUTHEAST KY STILL QUITE WARMER THAN THE NORTH LOCATIONS...THE BAND INDICATED THROUGH THE CENTRAL PORTION OF EAST KY...WILL MAINLY BE A RAIN PRODUCER WITH THE BEST CHANCE FOR ACCUMULATING SNOW ION THE HIGHER TERRAIN ALONG THE VA BORDER. AS WELL...NAM MODEL SOUNDINGS STILL SHOW A POOR DENDRITE GROWTH ZONE THROUGH MUCH OF THE EVENT...LOCATED FROM THE JKL POINT AND SOUTH. BASED ON ALL THESE FACTORS...HAVE KEPT THE SPS GOING WITH THE INCH POSSIBLE NORTH OF THE MOUNTAIN PARKWAY AND IN THE HIGHER TERRAIN ALONG THE VA BORDER. IF THE BAND IN THE NORTH DOES SLIDE SOUTH A BIT...THE BLUE GRASS COUNTIES WILL QUICKLY REACH ADVISORY CRITERIA. FOR THE REST OF THE SHORT TERM...A PROGRESSIVE PATTERN REMAINS...SUCH THAT...LOCATIONS THAT FINALLY BECOME COLD ENOUGH TO SUPPORT SNOW THIS EVENING AND TONIGHT...MUCH OF THE MOISTURE WILL BE OUT OF THE AREA WITH A FEW FLURRIES POSSIBLE. THE PATTERN WILL ALLOW A BRIEF STAY FOR THIS COLDER AIR MASS AS THURSDAY HIGH TEMPS WILL QUICKLY WARM INTO THE UPPER 40S...MELTING ANY SNOW THAT FALLS TODAY AND TONIGHT. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 341 AM EST WED FEB 13 2013 THE MODEL START OFF IN FAIRLY GOOD AGREEMENT WITH AN UPPER TROUGH EXTENDING ACROSS THE MIDWEST. THIS UPPER TROUGH WILL PUSH A WEAK FRONT ACROSS THE AREA ON FRIDAY BRINGING INITIALLY A MIX OF RAIN AND SNOW IN THE MORNING AND THEN TURNING TO ALL RAIN AS IT WARMS UP A LITTLE IN THE AFTERNOON AND THEN A MIX OF RAIN AND SNOW AGAIN IN THE EVENING WHEN THINGS COOL OFF AGAIN. AT WORST...A DUSTING OF SNOW IS EXPECTED WITH THIS SYSTEM. SOME FLURRIES OR VERY LIGHT SNOW IS POSSIBLE ON SATURDAY AS THE UPPER TROUGH MOVES THROUGH THE AREA. THIS IS ALSO WHERE THE MODELS REALLY BEGIN TO DIVERGE WITH THE ECMWF ABOUT 12 HOURS SLOWER WITH THE UPPER TROUGH PASSAGE. ALSO THE ECMWF HAS A MUCH SHARPER AND DEEPER UPPER TROUGH THAN THE GFS. THE MODELS THEN GET INTO BETTER AGREEMENT WITH A MORE ZONAL PATTERN DEVELOPING ACROSS THE US. THE NEXT SYSTEM TO MOVE ACROSS EASTERN KENTUCKY WILL BE ON TUESDAY. HERE THE ECMWF IS THE FASTER OF THE TWO SYSTEMS. DECIDED TO GO WITH THE FASTER ECMWF FOR THE TUESDAY SYSTEM. THE PATTERN THUS REMAINS ACTIVE...HOWEVER NO MAJOR SYSTEMS WITH BIG IMPACT ARE EXPECTED. FOR THE TEMPERATES...GENERALLY NUDGED THE MODEL BLEND TOWARD THE NEW AND GENERALLY WARMER ECMWF RAW DATA FOR THE TEMPERATURE FORECAST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 658 AM EST WED FEB 13 2013 WITH STILL A DRY LOWER LAYER TO OVERCOME...MVFR AND IFR CEILINGS WILL HOLD OFF TILL 14Z TO 15Z. PRECIP WILL FALL THROUGH THE MORNING ACROSS THE AREA LOWERING VIS TO MVFR AND IFR CONDITIONS ALONG WITH CEILINGS REMAINING OVER THE AREA THROUGH THE REST OF THE TAF PERIOD. PRECIP SHOULD END ACROSS EASTERN KENTUCKY BY 03Z WITH CEILINGS REMAINING THROUGH THE REST OF THE TAF PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...DUSTY SHORT TERM...SHALLENBERGER LONG TERM...JJ AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
703 AM EST WED FEB 13 2013 .Forecast Update... Issued at 655 AM EST Wed Feb 13 2013 We`re starting to see a rain/snow mix over southern Indiana and portions of north central KY this morning including the Louisville metro area. Updated the forecast to extend categorical POPs farther north into southern Indiana with up to 1 inch of slushy accums possible there as well. Radar imagery indicates moisture setting up farther north than previously forecast. Latest RAP run has a good handle on this. Will update and continue the SPS for this event. && .Short Term (Now through Thursday)... Issued at 325 AM EST Wed Feb 13 2013 ...Light Slushy Snow Accumulations Possible Today... As of 745Z, an upper trough was over MO with sfc low pressure over the Gulf States. Precipitation associated with this system stretched from western KY to eastern OK as of 745Z with rain observed over most areas ESE of the upper trough and snow or a rain/snow mix observed over portions of OK/MO/AR in the upper level trough. The 6Z NAM12 and last few RAP runs seem to have the best handle on the area of precipitation and general schematic of ptype. Overall timing of the best precip and forcing seems to be a little earlier than previously thought. Looks like the best dynamics and precip should fall over our region between 12-18Z. Also, the latest runs of the NAM and RAP have moved the best band of moderate to heavy precip...probably a heavy wet snow as observed out in MO...to the north. According to these models, the best snow band in which we could see 1-2 inches of wet, slushy snow would be in a corridor along the Ohio River to along the Western KY and Bluegrass Parkways. Other areas over southern Indiana and south central KY may see a brief mix of rain/snow...enough to create a dusting to a half inch before quickly melting off. There is still some uncertainty in where the band of moderate to heavy snow will set up so stay tuned to morning forecast updates. Also, because of the uncertainty, will continue with the SPS product instead of going with an advisory although one may be needed later this morning. So for today expect light rain to overspread the area before sunrise with possibly some snow grains mixing in over southern Indiana and northern KY at precip onset due to a deeper cold layer. After sunrise we`ll start to see colder air filter in with the upper trough causing precip to change over to a rain/snow mix and then probably all snow for a time over southern Indiana and central KY. The morning hours after sunrise through early afternoon will be the best time for a period of moderate to heavy wet snow resulting in slushy snow accumulations as high as 1-2 inches over north central KY. This period of wintry precip may cause some travel issues. We`ll continue to see a early afternoon before precip exits to our east by late afternoon/early evening. Once snow comes to an end over any location, quick melting can be expected as sfc temps are expected to be above freezing today. In fact, most locations will still top out in the upper 30s to lower 40s this afternoon despite any morning/early afternoon snow. For tonight and Thurs, expect dry conditions with partly cloudy skies. Low temps will be in the upper 20s to lower 30s tonight. An upper level trough and cold front will approach the region by Thurs evening. Ahead of the trough, though, Thurs will be quite warm with a strong southerly flow in place. High temps Thurs should be in the low to mid 50s. .Long Term (Thursday Night - Tuesday)... Issued at 320 AM EST Wed Feb 13 2013 ...A few shots for snow showers followed by a warm up and another strong storm system early next week... A lead shortwave will move across the Great Lakes on Thursday night, with the associated surface system dragging a moisture starved cold frontal boundary through the region. A secondary shortwave will quickly move across the Ohio Valley on Friday as overall trough envelopes the eastern CONUS. Friday looks to be the best setup for some snow showers across the area as enough deep moisture combines with steep low and mid level lapse rates, and an upslope surface component. Soundings for this time period do show some convective instability with saturation well into the -10 -20 C range across northern portions of the CWA. Surface temperatures may squeak into the mid and upper 30s on Friday, however thermal profile will be easily cold enough for all snow showers below 40 degrees, some of which could produce bursts of heavy snow and gusty winds. At this point, best location for snow looks to be across southern Indiana and north central Kentucky. As was mentioned in the previous forecast, these snow showers have the potential to cause an impact across the region with very light but quick accumulations. This setup will have to be monitored. We should see a lull in the activity on Friday night with subsidence behind the quickly departing shortwave. Temperatures will be much cooler with lows dropping into the mid 20s. By Saturday, confidence is low as to exact placement of trough axis. Models are still having trouble with the timing/placement of individual waves and the overall progression of the east CONUS trough amplification. Have continued the trend of a drier Saturday as a GFS/GEM/GFS ensemble mean consensus agree on an eastern solution with subsidence aloft already in place across the Ohio Valley on Saturday. The less consistent ECMWF still holds the axis to the west. Will only mention a slight chance of a snow shower east of I-65 to account for this. May be able to go completely dry for Saturday with the next set of model runs. Temperatures will be cooler than Friday with highs only topping out in the low and mid 30s. Saturday night/Sunday morning will be the coldest of the period as lows drop to around 20. Radiational cooling conditions will not be optimal as surface winds stay up a bit and some upper level clouds look to stream overhead. Therefore, cannot drop low too near dew points that will be in the lower teens. May be able to decouple a few of the coolest spots into the upper teens but the upper level cloud cover should mostly mitigate this. Saturday night through most of Monday should be dry as surface high pressure holds over the area and weak upper level ridging holds. Sunday will begin the warming trend with highs warming into the mid 30s to low 40s. Highs on Monday will be much milder with a return of southerly flow. The mercury should rebound to the low 50s in most spots. By Monday afternoon we will begin to focus on the next storm system that looks to impact the area through Tuesday. This system will develop as a lee surface low intensifies ahead of a digging trough over the central Plains. At this point the low looks to move from the southern Plains, northeastward either into the Ohio Valley or just north to the lower Great Lakes through Tuesday morning. This warmer solution would bring overrunning rain showers to the area late Monday afternoon, with more widespread rain moving into the area Monday night and early Tuesday. Temperatures will likely crash quickly behind the system on Tuesday afternoon as sharp trough moves through and may eventually have to mention rain changing to snow. Will stick with all rain for now as it is too early to mention these details, especially with the low track in question. Will also leave any thunder mention out of the forecast with the bulk of the precipitation as any moisture return/instability would be limited by short duration of southerly flow. This system will have to be watched however, as a more northerly solution or deeper sfc low would change the instability picture. Also, chose to disregard the more southern solution offered by the operational ECMWF. This seems to be the outlier, with a general consensus between the GFS/GEM/GFS ensemble mean/ECMWF ensemble mean of a northern solution. && .Aviation (12Z TAF Issuance)... Issued at 605 AM EST Wed Feb 13 2013 An upper level trough will pass through the area today with a sfc low pressure passing to our south. Precipitation associated with this weather system has already begun to spread northward into central KY this morning. At the beginning of TAF time, it should be raining near all TAF sites with SDF/LEX rains being more intermittent showers until deeper moisture overtakes the low level dry layer. After sunrise, good forcing will enter the region causing steady moderate banded precip over the region. It`s hard to say whether a moderate band will affect the TAF sites, but at least feel confident enough to include lower MVFR conditions this morning through early afternoon as the heavier precip moves through the region. Some IFR cigs may be possible in some of the heavier bands of precip especially near BWG but will not include in the TAF at this time as confidence is low. Rain is expected to be the predominant precip type for BWG, however, SDF/LEX could see a RASN mix in a moderate band. A RASN mix isn`t out of the realm of possibilities for BWG either, but seems most likely at SDF/LEX at this time. Will need to adjust as the precip bands set up this morning and move closer to our area. By mid to late afternoon, precip should move east of the TAF sites with conditions returning to high end MVFR and then VFR by this evening. Winds will be predominantly NNE as the weather system moves through the area this morning through mid afternoon. Winds will strengthen throughout the day likely exceeding 7kt at times. Winds will shift to the WNW behind this system by this evening. NAM model soundings indicate a layer of low level moisture for tomorrow morning which could indicate a light fog or low cigs. Will not place flight restrictions at the end of the TAFs for now, but it will be something to investigate further. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Update...........AMS Short Term.......AMS Long Term........BJS Aviation.........AMS
AREA FORECAST DISCUSSION
NWS JACKSON KY
658 AM EST WED FEB 13 2013 .UPDATE... ISSUED AT 658 AM EST WED FEB 13 2013 CURRENT CONDITIONS ACROSS EASTERN KENTUCKY HAVE PRECIP MOVING INTO THE AREA WITH RAIN REACHING THE GROUND IN THE SOUTH. HAVE UPDATED TO FINE TUNE POPS AND ANY COOLING EFFECTS TO TEMPS FROM THE RAINFALL. UPSTREAM...IT SEEMS THE BAND SETTING UP WILL STAY JUST NORTH SO WILL KEEP CURRENT SNOWFALL FORECAST IN PLACE. ONLY CONCERN RIGHT NOW IS THE COOLING EFFECTS AND SURFACE TEMPS OVER THE SOUTH AS SOME REPORTS OF MODERATE RAIN POSSIBLY REALLY COOLING SURFACE TEMPS. WILL BANK ON SURFACE TEMPS STAYING WARM ENOUGH THROUGH THE EARLY AFTERNOON BEFORE THE COLD AIR FINALLY CHANGES THE RAIN OVER THIS AFTERNOON. ALSO...MODEL SOUNDINGS CONTINUE TO SHOW DRY AIR AIR AT THE 10 DEGREE CELSIUS TEMPS AND HIGHER SO WILL KEEP THE INCH OR SNOW FORECAST NORTH OF THE MOUNTAIN PARKWAY AND IN THE HIGHEST ELEVATIONS SO NO NEW ZFP WAS NEEDED. && .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 423 AM EST WED FEB 13 2013 CURRENT 09Z ANALYSIS ACROSS THE AREA HAS WIDESPREAD CLOUD COVER OVER EASTERN KENTUCKY WITH PRECIP ALONG THE TN AND KY BORDER IN SOUTH CENTRAL KY DEVELOPING AND MOVING INTO THE AREA. CURRENT TEMPERATURES ACROSS THE SOUTHERN PORTION OF THE AREA ARE IN THE LOW 40S TO UPPER 30S. HOWEVER SURFACE TEMPS ALONG AND NORTH OF THE MOUNTAIN PARKWAY ARE COLD ENOUGH TO SUSTAIN SOME SNOWFALL AS THE PRECIP WILL CREEP INTO THE NORTHERN PORTION OF THE CWA BY 12Z. MET SAT DATA CURRENTLY SHOWS THE DEVELOPING SURFACE LOW OVER THE LOWER TN VALLEY AND SHIFTING OFF TO THE NORTHEAST. THE UPPER LOW IS LOCATED OVER SOUTHERN IL MOVING TO THE EAST NORTHEAST. CURRENT SHORT TERM MODELS INDICATE A BAND OF HEAVY PRECIP SETTING UP. THE CHALLENGE HERE IS THE LOCATION OF THE DEVELOPMENT. BOTH THE NAM AND GFS HAVE INDICATED A BAND OF HEAVIER PRECIP JUST SOUTH OF THE OH RIVER AND ALSO ANOTHER BAND GOING THROUGH CENTRAL EASTERN KY. THE HI RES HRRR ALSO SHOWS THIS BUT WITH THE SOUTHERN BAND NOT AS INTENSE. BASED ON CURRENT WV SHOWING MID LEVEL MOISTURE AND ADVECTING TOWARD THE UPPER OH VALLEY...HAVE GONE WITH THE BLUEGRASS AND LOCATIONS NORTH OF THE MOUNTAIN PARKWAY TO RECEIVE UP TO AN INCH OF SNOWFALL. CURRENT THOUGH IS WITH THE SOUTHEAST KY STILL QUITE WARMER THAN THE NORTH LOCATIONS...THE BAND INDICATED THROUGH THE CENTRAL PORTION OF EAST KY...WILL MAINLY BE A RAIN PRODUCER WITH THE BEST CHANCE FOR ACCUMULATING SNOW ION THE HIGHER TERRAIN ALONG THE VA BORDER. AS WELL...NAM MODEL SOUNDINGS STILL SHOW A POOR DENDRITE GROWTH ZONE THROUGH MUCH OF THE EVENT...LOCATED FROM THE JKL POINT AND SOUTH. BASED ON ALL THESE FACTORS...HAVE KEPT THE SPS GOING WITH THE INCH POSSIBLE NORTH OF THE MOUNTAIN PARKWAY AND IN THE HIGHER TERRAIN ALONG THE VA BORDER. IF THE BAND IN THE NORTH DOES SLIDE SOUTH A BIT...THE BLUE GRASS COUNTIES WILL QUICKLY REACH ADVISORY CRITERIA. FOR THE REST OF THE SHORT TERM...A PROGRESSIVE PATTERN REMAINS...SUCH THAT...LOCATIONS THAT FINALLY BECOME COLD ENOUGH TO SUPPORT SNOW THIS EVENING AND TONIGHT...MUCH OF THE MOISTURE WILL BE OUT OF THE AREA WITH A FEW FLURRIES POSSIBLE. THE PATTERN WILL ALLOW A BRIEF STAY FOR THIS COLDER AIR MASS AS THURSDAY HIGH TEMPS WILL QUICKLY WARM INTO THE UPPER 40S...MELTING ANY SNOW THAT FALLS TODAY AND TONIGHT. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 341 AM EST WED FEB 13 2013 THE MODEL START OFF IN FAIRLY GOOD AGREEMENT WITH AN UPPER TROUGH EXTENDING ACROSS THE MIDWEST. THIS UPPER TROUGH WILL PUSH A WEAK FRONT ACROSS THE AREA ON FRIDAY BRINGING INITIALLY A MIX OF RAIN AND SNOW IN THE MORNING AND THEN TURNING TO ALL RAIN AS IT WARMS UP A LITTLE IN THE AFTERNOON AND THEN A MIX OF RAIN AND SNOW AGAIN IN THE EVENING WHEN THINGS COOL OFF AGAIN. AT WORST...A DUSTING OF SNOW IS EXPECTED WITH THIS SYSTEM. SOME FLURRIES OR VERY LIGHT SNOW IS POSSIBLE ON SATURDAY AS THE UPPER TROUGH MOVES THROUGH THE AREA. THIS IS ALSO WHERE THE MODELS REALLY BEGIN TO DIVERGE WITH THE ECMWF ABOUT 12 HOURS SLOWER WITH THE UPPER TROUGH PASSAGE. ALSO THE ECMWF HAS A MUCH SHARPER AND DEEPER UPPER TROUGH THAN THE GFS. THE MODELS THEN GET INTO BETTER AGREEMENT WITH A MORE ZONAL PATTERN DEVELOPING ACROSS THE US. THE NEXT SYSTEM TO MOVE ACROSS EASTERN KENTUCKY WILL BE ON TUESDAY. HERE THE ECMWF IS THE FASTER OF THE TWO SYSTEMS. DECIDED TO GO WITH THE FASTER ECMWF FOR THE TUESDAY SYSTEM. THE PATTERN THUS REMAINS ACTIVE...HOWEVER NO MAJOR SYSTEMS WITH BIG IMPACT ARE EXPECTED. FOR THE TEMPERATES...GENERALLY NUDGED THE MODEL BLEND TOWARD THE NEW AND GENERALLY WARMER ECMWF RAW DATA FOR THE TEMPERATURE FORECAST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 658 AM EST WED FEB 13 2013 WITH STILL A DRY LOWER LAYER TO OVERCOME...MVFR AND IFR CEILINGS WILL HOLD OFF TILL 14Z TO 15Z. PRECIP WILL FALL THROUGH THE MORNING ACROSS THE AREA LOWERING VIS TO MVFR AND IFR CONDITIONS ALONG WITH CEILINGS REMAINING OVER THE AREA THROUGH THE REST OF THE TAF PERIOD. PRECIP SHOULD END ACROSS EASTERN KENTUCKY BY 03Z WITH CEILINGS REMAINING THROUGH THE REST OF THE TAF PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SHALLENBERGER SHORT TERM...SHALLENBERGER LONG TERM...JJ AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
609 AM EST WED FEB 13 2013 ...Updated Aviation Discussion... .Short Term (Now through Thursday)... Issued at 325 AM EST Wed Feb 13 2013 ...Light Slushy Snow Accumulations Possible Today... As of 745Z, an upper trough was over MO with sfc low pressure over the Gulf States. Precipitation associated with this system stretched from western KY to eastern OK as of 745Z with rain observed over most areas ESE of the upper trough and snow or a rain/snow mix observed over portions of OK/MO/AR in the upper level trough. The 6Z NAM12 and last few RAP runs seem to have the best handle on the area of precipitation and general schematic of ptype. Overall timing of the best precip and forcing seems to be a little earlier than previously thought. Looks like the best dynamics and precip should fall over our region between 12-18Z. Also, the latest runs of the NAM and RAP have moved the best band of moderate to heavy precip...probably a heavy wet snow as observed out in MO...to the north. According to these models, the best snow band in which we could see 1-2 inches of wet, slushy snow would be in a corridor along the Ohio River to along the Western KY and Bluegrass Parkways. Other areas over southern Indiana and south central KY may see a brief mix of rain/snow...enough to create a dusting to a half inch before quickly melting off. There is still some uncertainty in where the band of moderate to heavy snow will set up so stay tuned to morning forecast updates. Also, because of the uncertainty, will continue with the SPS product instead of going with an advisory although one may be needed later this morning. So for today expect light rain to overspread the area before sunrise with possibly some snow grains mixing in over southern Indiana and northern KY at precip onset due to a deeper cold layer. After sunrise we`ll start to see colder air filter in with the upper trough causing precip to change over to a rain/snow mix and then probably all snow for a time over southern Indiana and central KY. The morning hours after sunrise through early afternoon will be the best time for a period of moderate to heavy wet snow resulting in slushy snow accumulations as high as 1-2 inches over north central KY. This period of wintry precip may cause some travel issues. We`ll continue to see a early afternoon before precip exits to our east by late afternoon/early evening. Once snow comes to an end over any location, quick melting can be expected as sfc temps are expected to be above freezing today. In fact, most locations will still top out in the upper 30s to lower 40s this afternoon despite any morning/early afternoon snow. For tonight and Thurs, expect dry conditions with partly cloudy skies. Low temps will be in the upper 20s to lower 30s tonight. An upper level trough and cold front will approach the region by Thurs evening. Ahead of the trough, though, Thurs will be quite warm with a strong southerly flow in place. High temps Thurs should be in the low to mid 50s. .Long Term (Thursday Night - Tuesday)... Issued at 320 AM EST Wed Feb 13 2013 ...A few shots for snow showers followed by a warm up and another strong storm system early next week... A lead shortwave will move across the Great Lakes on Thursday night, with the associated surface system dragging a moisture starved cold frontal boundary through the region. A secondary shortwave will quickly move across the Ohio Valley on Friday as overall trough envelopes the eastern CONUS. Friday looks to be the best setup for some snow showers across the area as enough deep moisture combines with steep low and mid level lapse rates, and an upslope surface component. Soundings for this time period do show some convective instability with saturation well into the -10 -20 C range across northern portions of the CWA. Surface temperatures may squeak into the mid and upper 30s on Friday, however thermal profile will be easily cold enough for all snow showers below 40 degrees, some of which could produce bursts of heavy snow and gusty winds. At this point, best location for snow looks to be across southern Indiana and north central Kentucky. As was mentioned in the previous forecast, these snow showers have the potential to cause an impact across the region with very light but quick accumulations. This setup will have to be monitored. We should see a lull in the activity on Friday night with subsidence behind the quickly departing shortwave. Temperatures will be much cooler with lows dropping into the mid 20s. By Saturday, confidence is low as to exact placement of trough axis. Models are still having trouble with the timing/placement of individual waves and the overall progression of the east CONUS trough amplification. Have continued the trend of a drier Saturday as a GFS/GEM/GFS ensemble mean consensus agree on an eastern solution with subsidence aloft already in place across the Ohio Valley on Saturday. The less consistent ECMWF still holds the axis to the west. Will only mention a slight chance of a snow shower east of I-65 to account for this. May be able to go completely dry for Saturday with the next set of model runs. Temperatures will be cooler than Friday with highs only topping out in the low and mid 30s. Saturday night/Sunday morning will be the coldest of the period as lows drop to around 20. Radiational cooling conditions will not be optimal as surface winds stay up a bit and some upper level clouds look to stream overhead. Therefore, cannot drop low too near dew points that will be in the lower teens. May be able to decouple a few of the coolest spots into the upper teens but the upper level cloud cover should mostly mitigate this. Saturday night through most of Monday should be dry as surface high pressure holds over the area and weak upper level ridging holds. Sunday will begin the warming trend with highs warming into the mid 30s to low 40s. Highs on Monday will be much milder with a return of southerly flow. The mercury should rebound to the low 50s in most spots. By Monday afternoon we will begin to focus on the next storm system that looks to impact the area through Tuesday. This system will develop as a lee surface low intensifies ahead of a digging trough over the central Plains. At this point the low looks to move from the southern Plains, northeastward either into the Ohio Valley or just north to the lower Great Lakes through Tuesday morning. This warmer solution would bring overrunning rain showers to the area late Monday afternoon, with more widespread rain moving into the area Monday night and early Tuesday. Temperatures will likely crash quickly behind the system on Tuesday afternoon as sharp trough moves through and may eventually have to mention rain changing to snow. Will stick with all rain for now as it is too early to mention these details, especially with the low track in question. Will also leave any thunder mention out of the forecast with the bulk of the precipitation as any moisture return/instability would be limited by short duration of southerly flow. This system will have to be watched however, as a more northerly solution or deeper sfc low would change the instability picture. Also, chose to disregard the more southern solution offered by the operational ECMWF. This seems to be the outlier, with a general consensus between the GFS/GEM/GFS ensemble mean/ECMWF ensemble mean of a northern solution. && .Aviation (12Z TAF Issuance)... Issued at 605 AM EST Wed Feb 13 2013 An upper level trough will pass through the area today with a sfc low pressure passing to our south. Precipitation associated with this weather system has already begun to spread northward into central KY this morning. At the beginning of TAF time, it should be raining near all TAF sites with SDF/LEX rains being more intermittent showers until deeper moisture overtakes the low level dry layer. After sunrise, good forcing will enter the region causing steady moderate banded precip over the region. It`s hard to say whether a moderate band will affect the TAF sites, but at least feel confident enough to include lower MVFR conditions this morning through early afternoon as the heavier precip moves through the region. Some IFR cigs may be possible in some of the heavier bands of precip especially near BWG but will not include in the TAF at this time as confidence is low. Rain is expected to be the predominant precip type for BWG, however, SDF/LEX could see a RASN mix in a moderate band. A RASN mix isn`t out of the realm of possibilities for BWG either, but seems most likely at SDF/LEX at this time. Will need to adjust as the precip bands set up this morning and move closer to our area. By mid to late afternoon, precip should move east of the TAF sites with conditions returning to high end MVFR and then VFR by this evening. Winds will be predominantly NNE as the weather system moves through the area this morning through mid afternoon. Winds will strengthen throughout the day likely exceeding 7kt at times. Winds will shift to the WNW behind this system by this evening. NAM model soundings indicate a layer of low level moisture for tomorrow morning which could indicate a light fog or low cigs. Will not place flight restrictions at the end of the TAFs for now, but it will be something to investigate further. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Short Term.......AMS Long Term........BJS Aviation.........AMS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
508 AM CST WED FEB 13 2013 .AVIATION...12Z TAF. CONDITIONS WILL REMAIN AT VFR THROUGH THE TAF PERIOD. WEST WINDS WILL INCREASE THIS AFTN AHEAD OF AN APPROACHING FRONTAL BOUNDARY WITH GUSTS OVER 20KTS POSSIBLE. A COLD FRONTAL BOUNDARY WILL CROSS THE TERMINAL TONIGHT...WITH WINDS SWITCHING NORTHWESTERLY AND INCREASING...SETTING THE STAGE FOR A WINDY DAY ON THURSDAY...JUST BEYOND THE TAF PERIOD. PERIODS OF MID/HIGH CLOUDS WILL CROSS GRI WITH AN OCCASIONAL VFR CEILING. && .PREV DISCUSSION... /ISSUED 453 AM CST WED FEB 13 2013/ SHORT TERM...THROUGH FRIDAY NIGHT. THE MAIN STORIES THROUGH THE NEXT 72 HOURS INVOLVE A DOWNWARD TREND IN TEMPS AFTER A VERY MILD ONE TODAY...STRONG NORTHWEST WINDS ON THURSDAY THAT MAY VERY WELL REQUIRE A WIND ADVISORY ISSUANCE FOR AT LEAST PARTS OF THE AREA...AND THE POSSIBILITY OF A FEW ROUNDS OF PASSING FLURRIES DURING THE THURSDAY AFTERNOON THROUGH FRIDAY EVENING TIME FRAME BUT WITH LITTLE...IF ANY RISK OF ACCUMULATING SNOW. IN ADDITION...THE COMBINATION OF WARM AIR AND/OR GUSTY WINDS WILL PROMOTE AT LEAST SOME ELEVATED...BUT LIKELY NON-CRITICAL...FIRE DANGER IN PARTS OF THE AREA OVER THE NEXT FEW DAYS. THESE FIRE WEATHER CONCERNS ARE FURTHER DISCUSSED IN THE SEPARATE SECTION BELOW. 09Z CENTRAL PLAINS OBJECTIVE SURFACE ANALYSIS REVEALED A BROAD AREA OF HIGH PRESSURE EXTENDING EASTWARD OUT OF THE ROCKIES...WITH POSSIBLY A VERY SUBTLE TROUGH AXIS EXTENDING FROM FAR SOUTHEAST NEB INTO SOUTHWEST KS. THIS REGIME WAS PROMOTING FAIRLY STEADY 5-10 MPH WESTERLY BREEZES ACROSS THE MAJORITY OF THE CWA...WHICH ALONG WITH AN INCOMING BATCH OF HIGH LEVEL CLOUDS SHOULD KEEP MOST AREAS UP INTO THE 21-25 DEGREE RANGE FOR MORNING LOW TEMPS. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA SHOWED THE CENTRAL PLAINS UNDER NORTH-NORTHWEST FLOW ALOFT...IN BETWEEN THE SOUTHERN STREAM SHORTWAVE TROUGH ALONG THE MO/AR BORDER...AND A PARADE OF LOW AMPLITUDE DISTURBANCES ASSOCIATED WITH THE NORTHERN STREAM JET IN THE SOUTHWEST CANADA/MONTANA AREA. 11-3.9 MICRON SATELLITE IMAGERY REVEALS CLEAR SKIES OVER MOST OF THE CWA BUT AT LEAST A THIN LAYER OF HIGH CLOUD WILL BE PASSING OVER MOST OF THE AREA BETWEEN NOW AND SUNRISE. TODAY WILL BE THE WELL-ANTICIPATED WARMEST DAY OF THE WEEK FOR THE ENTIRE CWA. ALOFT...NORTHWEST FLOW WILL PERSIST...WITH ONLY THE MOST SUBTLE OF MOISTURE-STARVED DISTURBANCES RIDING THROUGH THE FLOW AS THE AREA REMAINS JUST SOUTH OF A SLIGHTLY STRONGER WAVE CROSSING THE DAKOTAS THIS AFTERNOON. AS A RESULT...SKY COVER WILL BE SOMEWHAT VARIABLE TODAY...GENERALLY AVERAGING PARTLY CLOUDY BUT ALTERNATING BETWEEN PERIODS OF PLENTIFUL SUNSHINE AND PASSING BATCHES OF MID-HIGH LEVEL CLOUDS. AT THE SURFACE...THE WEST- NORTHWEST WIND REGIME WILL PERSIST...AND INCREASE IN SPEED IN RESPONSE TO DEEPENING MIXING TO AT LEAST THE 850-800MB LAYER. AS A RESULT...UPPED WIND SPEEDS A BIT FROM PREVIOUS FORECAST...AS THE LATE MORNING-LATE AFTERNOON HOURS WILL FEATURE SUSTAINED SPEEDS AT LEAST 15-20 MPH WITH SOME GUSTS 25+ MPH. THE DEEP MIXING WILL COMBINE WITH SLIGHTLY WARMER AIR MOVING IN ALOFT FROM THE WEST TO RESULT IN HIGH TEMPERATURES WELL INTO THE 50S NEARLY ALL AREAS. NUDGED UP HIGH TEMPS 2-3 DEGREES FROM PREVIOUS GRIDS IN MOST AREAS...GETTING MOST PLACES UP BETWEEN 52-55 DEGREES EXCEPT SLIGHTLY COOLER UPPER 40S MAINLY IN PARTS OF VALLEY COUNTY WHERE SOME SNOW PACK REMAINS. THESE FORECAST HIGHS ARE RIGHT IN LINE WITH 07Z RAP HOURLY TEMPS...WHICH HAVE PERFORMED QUITE WELL THE PAST TWO DAYS. TONIGHT...HAVE HIGH CONFIDENCE THAT IT WILL REMAIN PRECIP- FREE...BUT THE LEADING EDGES OF A COLD FRONT WILL START BLEEDING DOWN FROM THE NORTH...IN RESPONSE TO A PARADE OF NORTHWEST-FLOW CLIPPER WAVES ALOFT THAT WILL FOCUS ALONG AN AXIS FROM NORTH DAKOTA-IOWA. SKY COVER WILL REMAIN VARIABLE THROUGH THE NIGHT...AS STEADY WEST-NORTHWEST BREEZES REMAIN UP BETWEEN 10-20 MPH WITH SOME HIGHER GUSTS. DESPITE THE WEAK COLD AIR ADVECTION...THESE WINDS AND PASSING CLOUDS SHOULD HAVE NO PROBLEM KEEPING OVERNIGHT LOW TEMPERATURES AT LEAST SLIGHTLY WARMER THAN THOSE THIS MORNING...AND MADE LITTLE CHANGE KEEPING MOST AREAS UP BETWEEN 25-29 DEGREES...AND WOULD NOT BE SURPRISED TO SEE A BIT GREATER COVERAGE OF LOWS RIGHT AROUND 30 THAN CURRENTLY DEPICTED. THURSDAY IS UNDOUBTEDLY THE MOST ACTIVE OF THE SHORT TERM PERIODS...MAINLY DUE TO STRONG WINDS. SINCE 24 HOURS AGO...MOST MODELS/GUIDANCE HAVE CONTINUED TRENDING UPWARD A BIT WITH NORTHWESTERLY SPEEDS. FOCUSING FIRST ALOFT...AS THE DAY WEARS ON A SMALL BUT FAIRLY VIGOROUS MID LEVEL SHORTWAVE TROUGH WILL DROP SOUTHWARD OUT OF THE DAKOTAS INTO NEB/IA. MEANWHILE AT THE SURFACE...THE PRESSURE GRADIENT WILL RAMP UP IN RESPONSE TO INCREASING HIGH PRESSURE EMANATING FROM AN EXPANSIVE NORTHERN ROCKIES RIDGE. ONCE DIURNAL MIXING KICKS IN AND LOW LEVEL LAPSE RATES STEEPEN...THE 06Z NAM ADVERTISES MIXING TO DEEPEN WELL UP INTO THE 800MB TO POSSIBLY 700MB RANGE...WITH AVERAGING WIND SPEEDS THROUGH THIS MIXED LAYER EASILY SUPPORTING AT LEAST LOW-END ADVISORY SUSTAINED SPEEDS BETWEEN 30-35 MPH AND GUSTS TO AROUND 45 MPH. WILL ADD THIS STRONG WIND MENTION TO THE HAZARDOUS WEATHER OUTLOOK...BUT GIVEN IT IS STILL 3 PERIODS AWAY WILL HOLD OFF ON A WIND ADVISORY FOR NOW...AND GIVE DAY SHIFT ANOTHER LOOK TO DETERMINE WHETHER AN ADVISORY MAY BE JUSTIFIED FOR ALL 30 COUNTIES...OR MAINLY FOR THE NORTHERN 1/2 OF THE CWA WHICH LOOKS SLIGHTLY MORE FAVORABLE TO MEET 30+ MPH FOR SEVERAL HOURS VERSUS SOUTHERN ZONES. THE MAIN WINDOW FOR THE STRONGEST WINDS GENERALLY LOOKS TO TARGET THE 11 AM-6 PM TIME FRAME. AS FOR PRECIP CHANCES...HAVE NOTHING MENTIONED DURING THE MORNING...BUT HAVE RE- INTRODUCED SOME FLURRY CHANCES FOR SOME AREAS NORTH OF I-80 DURING THE AFTERNOON AS LOW LEVEL STRATUS SWEEPS IN FROM THE NORTH. NOT THINKING ANYTHING ACCUMULATING AT THIS POINT...WITH BETTER CHANCES FOR A LIGHT DUSTING FOCUSING JUST NORTH OF OUR AREA. TEMP- WISE...IF IT WASN/T FOR THE WIND IT REALLY WOULDN/T FEEL TOO BAD...AND ONLY MADE MINOR TWEAKS TO HIGHS RANGING FROM UPPER 30S FAR NORTH...LOW 40S CENTRAL AND MID 40S IN KS ZONES. TAKING A BIT BROADER LOOK AT THE THURSDAY NIGHT THROUGH FRIDAY NIGHT TIME FRAME...THE BIG PICTURE ALOFT INVOLVES THE CENTRAL PLAINS REMAINING UNDER NORTHWEST FLOW ALOFT AS A CONTINUING PARADE OF MID LEVEL SHORTWAVE TROUGHS ROTATING SOUTH-SOUTHEAST OUT OF CANADA WILL CARVE OUT AN EXPANSIVE LONGWAVE TROUGH THAT WILL DOMINATE THE EASTERN TWO-THIRDS OF THE NATION. ON THURSDAY NIGHT...THE INITIAL SHORTWAVE TROUGH WILL PASS JUST SOUTHEAST OF OUR AREA...WHILE UPSTREAM THE NEXT MAIN ONE ENTERS THE DAKOTAS. WIND SPEEDS WILL EASE DOWN QUITE A BIT...ESPECIALLY POST-MIDNIGHT WHEN SPEEDS DECREASE INTO THE 5-10 MPH RANGE. ALTHOUGH SOME AREAS MAY NOT SEE A SINGLE SNOWFLAKE...OPTED TO KEEP THE GRIDS AS SIMPLE AS POSSIBLE AND BLANKET THE ENTIRE CWA WITH A SLIGHT CHANCE OF FLURRIES ALL THE WAY FROM THURSDAY NIGHT THROUGH FRIDAY EVENING AS THIS PATTERN OFTEN EVOKES SMALL-SCALE PATCHES OR BANDS OF NON- MEASURABLE SNOW UNDERNEATH THE UPPER JET EXIT REGION...ESPECIALLY IF SOME OF THE PASSING LOWER STRATUS HAS FAVORABLE DENDRITIC TEMPERATURES. ALTHOUGH SUPPOSE A SMALL PERCENTAGE OF THE CWA COULD SEE A LIGHT MEASURABLE DUSTING...ITS TOO EARLY TO DETERMINE WHERE THIS MIGHT EVEN BE...SO CANNOT JUSTIFY A MEASURABLE 20+ POP ANYWHERE AT THIS TIME FRAME. WINDS ON FRIDAY WILL REMAIN FROM THE NORTH-NORTHWEST BUT DO NOT APPEAR NEARLY AS STRONG AS THURSDAY WITH SUSTAINED SPEEDS GENERALLY TOPPING OUT AROUND 15 MPH. AS FOR TEMPS...MADE ONLY A SMALL DOWNWARD NUDGE TO THURSDAY NIGHT WITH MOST AREAS 16-20 DEGREES. FRIDAY STILL SHOULD BE THE COLDEST DAY OF THE WEEK...BUT ACTUALLY NUDGED UP VALUES A BIT IN SOME AREAS DUE TO DECENT MIXING POTENTIAL...RANGING FROM MID 30S IN MOST NEB ZONES TO NEAR 40 IN KS. BY MIDNIGHT FRIDAY NIGHT...ANY FLURRY RISK SHOULD BE OVER WITH AS THE BACK EDGE OF THE LAST IN A SERIES OF MID LEVEL SHORTWAVE TROUGHS EXITS THE AREA. LONG TERM...SATURDAY THROUGH TUESDAY. DRY CONDITIONS ARE FORECAST THROUGH THE EXTENDED PERIODS. ON SATURDAY...THE PATTERN ALOFT WILL FEATURE A TROUGH MOVING INTO THE PACIFIC NORTHWEST...RIDGING OVER THE ROCKIES AND A LONGWAVE TROUGH FROM THE HUDSON BAY SOUTH TO THE GULF COAST STATES. HEIGHTS WILL RISE ACROSS THE CENTRAL PLAINS OVER THE WEEKEND AS THE WESTERN RIDGE BUILDS ONTO PLAINS AND THE COLD AIRMASS ASSOCIATED WITH THE TROUGH TO THE EAST DEPARTS. THE RIDGE BEGINS TO BREAK DOWN SUNDAY AS AN UPSTREAM TROUGH REACHES THE NORTH CENTRAL ROCKIES. THIS NEXT TROUGH AND ASSOCIATED COLD FRONT CROSSES THE CENTRAL PLAINS SUNDAY NIGHT/MONDAY...BRINGING ANOTHER ROUND OF COLD AIR TO START THE WORKWEEK. TEMPERATURE WISE...TEMPS BEGIN TO RECOVER ON SATURDAY BEHIND THE UPPER TROUGH...THEN SUNDAY WILL BE THE WARMEST OF THE EXTENDED PERIODS WITH THE MILD AIRMASS IN PLACE AHEAD OF THE NEXT APPROACHING COLD FRONT/SYSTEM. HIGHS SUNDAY ARE LOOKING WELL ABOVE NORMAL IN THE 50S...THEN FOLLOWING COLD FROPA TEMPS RETURN CLOSER TO FEBRUARY NORMALS FOR MON/TUES. FIRE WEATHER...ALTHOUGH OUTRIGHT CRITICAL FIRE WEATHER THRESHOLDS ARE CURRENTLY NOT FORECAST DURING THE NEXT FEW DAYS...AT LEAST PARTS OF THE CWA BEAR WATCHING FOR SOME ELEVATED TO NEAR-CRITICAL COMBINATIONS OF WIND AND RELATIVE HUMIDITY. STARTING OFF TODAY...WEST-NORTHWEST SUSTAINED WIND SPEEDS WILL AVERAGE 15-20 MPH IN NEARLY ALL AREAS...WITH SPORADIC TO FREQUENT GUSTS TO 25+ MPH EXPECTED. FORTUNATELY...AFTERNOON RELATIVE HUMIDITY VALUES ACROSS MOST OF THE ARE FORECAST TO HOLD SLIGHTLY ABOVE CRITICAL LEVELS IN THE 25-30 PERCENT RANGE. HOWEVER...IT COULD BE A CLOSE CALL ESPECIALLY IN PARTS OF PHILLIPS/ROOKS/OSBORNE COUNTIES IN KANSAS...WHERE RH VALUES COULD EDGE A BIT CLOSER TO 20 PERCENT. WILL INTRODUCE AN ELEVATED FIRE DANGER MENTION INTO THE HAZARDOUS WEATHER OUTLOOK MAINLY FOR THIS AREA. TURNING TO THURSDAY...AS OUTLINED ABOVE STRONG SUSTAINED WINDS AROUND 30 MPH OR HIGHER ARE FORECAST ACROSS NEARLY THE ENTIRE CWA. FORTUNATELY...COOLER TEMPERATURES WILL KEEP AFTERNOON RH PERCENTAGES ABOVE 30 PERCENT ACROSS NEBRASKA ZONES...BUT KS ZONES COULD SEE VALUES CREEP DOWN CLOSER TO 25 PERCENT. BOTTOM LINE IS...WHILE NO MAJOR FIRE DANGER ISSUES ARE ANTICIPATED THESE NEXT FEW DAYS...SOME CAUTION MAY NEED TAKEN...AND HOURLY RELATIVE HUMIDITY TRENDS THESE NEXT FEW AFTERNOONS WILL NEED WATCHED CLOSELY TO MAKE SURE THERE ARE NO SURPRISES DROPPING BELOW 20 PERCENT. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM/FIRE WEATHER...PFANNKUCH LONG TERM/AVIATION...FAY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
453 AM CST WED FEB 13 2013 .SHORT TERM...THROUGH FRIDAY NIGHT. THE MAIN STORIES THROUGH THE NEXT 72 HOURS INVOLVE A DOWNWARD TREND IN TEMPS AFTER A VERY MILD ONE TODAY...STRONG NORTHWEST WINDS ON THURSDAY THAT MAY VERY WELL REQUIRE A WIND ADVISORY ISSUANCE FOR AT LEAST PARTS OF THE AREA...AND THE POSSIBILITY OF A FEW ROUNDS OF PASSING FLURRIES DURING THE THURSDAY AFTERNOON THROUGH FRIDAY EVENING TIME FRAME BUT WITH LITTLE...IF ANY RISK OF ACCUMULATING SNOW. IN ADDITION...THE COMBINATION OF WARM AIR AND/OR GUSTY WINDS WILL PROMOTE AT LEAST SOME ELEVATED...BUT LIKELY NON-CRITICAL...FIRE DANGER IN PARTS OF THE AREA OVER THE NEXT FEW DAYS. THESE FIRE WEATHER CONCERNS ARE FURTHER DISCUSSED IN THE SEPARATE SECTION BELOW. 09Z CENTRAL PLAINS OBJECTIVE SURFACE ANALYSIS REVEALED A BROAD AREA OF HIGH PRESSURE EXTENDING EASTWARD OUT OF THE ROCKIES...WITH POSSIBLY A VERY SUBTLE TROUGH AXIS EXTENDING FROM FAR SOUTHEAST NEB INTO SOUTHWEST KS. THIS REGIME WAS PROMOTING FAIRLY STEADY 5-10 MPH WESTERLY BREEZES ACROSS THE MAJORITY OF THE CWA...WHICH ALONG WITH AN INCOMING BATCH OF HIGH LEVEL CLOUDS SHOULD KEEP MOST AREAS UP INTO THE 21-25 DEGREE RANGE FOR MORNING LOW TEMPS. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA SHOWED THE CENTRAL PLAINS UNDER NORTH-NORTHWEST FLOW ALOFT...IN BETWEEN THE SOUTHERN STREAM SHORTWAVE TROUGH ALONG THE MO/AR BORDER...AND A PARADE OF LOW AMPLITUDE DISTURBANCES ASSOCIATED WITH THE NORTHERN STREAM JET IN THE SOUTHWEST CANADA/MONTANA AREA. 11-3.9 MICRON SATELLITE IMAGERY REVEALS CLEAR SKIES OVER MOST OF THE CWA BUT AT LEAST A THIN LAYER OF HIGH CLOUD WILL BE PASSING OVER MOST OF THE AREA BETWEEN NOW AND SUNRISE. TODAY WILL BE THE WELL-ANTICIPATED WARMEST DAY OF THE WEEK FOR THE ENTIRE CWA. ALOFT...NORTHWEST FLOW WILL PERSIST...WITH ONLY THE MOST SUBTLE OF MOISTURE-STARVED DISTURBANCES RIDING THROUGH THE FLOW AS THE AREA REMAINS JUST SOUTH OF A SLIGHTLY STRONGER WAVE CROSSING THE DAKOTAS THIS AFTERNOON. AS A RESULT...SKY COVER WILL BE SOMEWHAT VARIABLE TODAY...GENERALLY AVERAGING PARTLY CLOUDY BUT ALTERNATING BETWEEN PERIODS OF PLENTIFUL SUNSHINE AND PASSING BATCHES OF MID-HIGH LEVEL CLOUDS. AT THE SURFACE...THE WEST- NORTHWEST WIND REGIME WILL PERSIST...AND INCREASE IN SPEED IN RESPONSE TO DEEPENING MIXING TO AT LEAST THE 850-800MB LAYER. AS A RESULT...UPPED WIND SPEEDS A BIT FROM PREVIOUS FORECAST...AS THE LATE MORNING-LATE AFTERNOON HOURS WILL FEATURE SUSTAINED SPEEDS AT LEAST 15-20 MPH WITH SOME GUSTS 25+ MPH. THE DEEP MIXING WILL COMBINE WITH SLIGHTLY WARMER AIR MOVING IN ALOFT FROM THE WEST TO RESULT IN HIGH TEMPERATURES WELL INTO THE 50S NEARLY ALL AREAS. NUDGED UP HIGH TEMPS 2-3 DEGREES FROM PREVIOUS GRIDS IN MOST AREAS...GETTING MOST PLACES UP BETWEEN 52-55 DEGREES EXCEPT SLIGHTLY COOLER UPPER 40S MAINLY IN PARTS OF VALLEY COUNTY WHERE SOME SNOW PACK REMAINS. THESE FORECAST HIGHS ARE RIGHT IN LINE WITH 07Z RAP HOURLY TEMPS...WHICH HAVE PERFORMED QUITE WELL THE PAST TWO DAYS. TONIGHT...HAVE HIGH CONFIDENCE THAT IT WILL REMAIN PRECIP- FREE...BUT THE LEADING EDGES OF A COLD FRONT WILL START BLEEDING DOWN FROM THE NORTH...IN RESPONSE TO A PARADE OF NORTHWEST-FLOW CLIPPER WAVES ALOFT THAT WILL FOCUS ALONG AN AXIS FROM NORTH DAKOTA-IOWA. SKY COVER WILL REMAIN VARIABLE THROUGH THE NIGHT...AS STEADY WEST-NORTHWEST BREEZES REMAIN UP BETWEEN 10-20 MPH WITH SOME HIGHER GUSTS. DESPITE THE WEAK COLD AIR ADVECTION...THESE WINDS AND PASSING CLOUDS SHOULD HAVE NO PROBLEM KEEPING OVERNIGHT LOW TEMPERATURES AT LEAST SLIGHTLY WARMER THAN THOSE THIS MORNING...AND MADE LITTLE CHANGE KEEPING MOST AREAS UP BETWEEN 25-29 DEGREES...AND WOULD NOT BE SURPRISED TO SEE A BIT GREATER COVERAGE OF LOWS RIGHT AROUND 30 THAN CURRENTLY DEPICTED. THURSDAY IS UNDOUBTEDLY THE MOST ACTIVE OF THE SHORT TERM PERIODS...MAINLY DUE TO STRONG WINDS. SINCE 24 HOURS AGO...MOST MODELS/GUIDANCE HAVE CONTINUED TRENDING UPWARD A BIT WITH NORTHWESTERLY SPEEDS. FOCUSING FIRST ALOFT...AS THE DAY WEARS ON A SMALL BUT FAIRLY VIGOROUS MID LEVEL SHORTWAVE TROUGH WILL DROP SOUTHWARD OUT OF THE DAKOTAS INTO NEB/IA. MEANWHILE AT THE SURFACE...THE PRESSURE GRADIENT WILL RAMP UP IN RESPONSE TO INCREASING HIGH PRESSURE EMANATING FROM AN EXPANSIVE NORTHERN ROCKIES RIDGE. ONCE DIURNAL MIXING KICKS IN AND LOW LEVEL LAPSE RATES STEEPEN...THE 06Z NAM ADVERTISES MIXING TO DEEPEN WELL UP INTO THE 800MB TO POSSIBLY 700MB RANGE...WITH AVERAGING WIND SPEEDS THROUGH THIS MIXED LAYER EASILY SUPPORTING AT LEAST LOW-END ADVISORY SUSTAINED SPEEDS BETWEEN 30-35 MPH AND GUSTS TO AROUND 45 MPH. WILL ADD THIS STRONG WIND MENTION TO THE HAZARDOUS WEATHER OUTLOOK...BUT GIVEN IT IS STILL 3 PERIODS AWAY WILL HOLD OFF ON A WIND ADVISORY FOR NOW...AND GIVE DAY SHIFT ANOTHER LOOK TO DETERMINE WHETHER AN ADVISORY MAY BE JUSTIFIED FOR ALL 30 COUNTIES...OR MAINLY FOR THE NORTHERN 1/2 OF THE CWA WHICH LOOKS SLIGHTLY MORE FAVORABLE TO MEET 30+ MPH FOR SEVERAL HOURS VERSUS SOUTHERN ZONES. THE MAIN WINDOW FOR THE STRONGEST WINDS GENERALLY LOOKS TO TARGET THE 11 AM-6 PM TIME FRAME. AS FOR PRECIP CHANCES...HAVE NOTHING MENTIONED DURING THE MORNING...BUT HAVE RE- INTRODUCED SOME FLURRY CHANCES FOR SOME AREAS NORTH OF I-80 DURING THE AFTERNOON AS LOW LEVEL STRATUS SWEEPS IN FROM THE NORTH. NOT THINKING ANYTHING ACCUMULATING AT THIS POINT...WITH BETTER CHANCES FOR A LIGHT DUSTING FOCUSING JUST NORTH OF OUR AREA. TEMP- WISE...IF IT WASN/T FOR THE WIND IT REALLY WOULDN/T FEEL TOO BAD...AND ONLY MADE MINOR TWEAKS TO HIGHS RANGING FROM UPPER 30S FAR NORTH...LOW 40S CENTRAL AND MID 40S IN KS ZONES. TAKING A BIT BROADER LOOK AT THE THURSDAY NIGHT THROUGH FRIDAY NIGHT TIME FRAME...THE BIG PICTURE ALOFT INVOLVES THE CENTRAL PLAINS REMAINING UNDER NORTHWEST FLOW ALOFT AS A CONTINUING PARADE OF MID LEVEL SHORTWAVE TROUGHS ROTATING SOUTH-SOUTHEAST OUT OF CANADA WILL CARVE OUT AN EXPANSIVE LONGWAVE TROUGH THAT WILL DOMINATE THE EASTERN TWO-THIRDS OF THE NATION. ON THURSDAY NIGHT...THE INITIAL SHORTWAVE TROUGH WILL PASS JUST SOUTHEAST OF OUR AREA...WHILE UPSTREAM THE NEXT MAIN ONE ENTERS THE DAKOTAS. WIND SPEEDS WILL EASE DOWN QUITE A BIT...ESPECIALLY POST-MIDNIGHT WHEN SPEEDS DECREASE INTO THE 5-10 MPH RANGE. ALTHOUGH SOME AREAS MAY NOT SEE A SINGLE SNOWFLAKE...OPTED TO KEEP THE GRIDS AS SIMPLE AS POSSIBLE AND BLANKET THE ENTIRE CWA WITH A SLIGHT CHANCE OF FLURRIES ALL THE WAY FROM THURSDAY NIGHT THROUGH FRIDAY EVENING AS THIS PATTERN OFTEN EVOKES SMALL-SCALE PATCHES OR BANDS OF NON- MEASURABLE SNOW UNDERNEATH THE UPPER JET EXIT REGION...ESPECIALLY IF SOME OF THE PASSING LOWER STRATUS HAS FAVORABLE DENDRITIC TEMPERATURES. ALTHOUGH SUPPOSE A SMALL PERCENTAGE OF THE CWA COULD SEE A LIGHT MEASURABLE DUSTING...ITS TOO EARLY TO DETERMINE WHERE THIS MIGHT EVEN BE...SO CANNOT JUSTIFY A MEASURABLE 20+ POP ANYWHERE AT THIS TIME FRAME. WINDS ON FRIDAY WILL REMAIN FROM THE NORTH-NORTHWEST BUT DO NOT APPEAR NEARLY AS STRONG AS THURSDAY WITH SUSTAINED SPEEDS GENERALLY TOPPING OUT AROUND 15 MPH. AS FOR TEMPS...MADE ONLY A SMALL DOWNWARD NUDGE TO THURSDAY NIGHT WITH MOST AREAS 16-20 DEGREES. FRIDAY STILL SHOULD BE THE COLDEST DAY OF THE WEEK...BUT ACTUALLY NUDGED UP VALUES A BIT IN SOME AREAS DUE TO DECENT MIXING POTENTIAL...RANGING FROM MID 30S IN MOST NEB ZONES TO NEAR 40 IN KS. BY MIDNIGHT FRIDAY NIGHT...ANY FLURRY RISK SHOULD BE OVER WITH AS THE BACK EDGE OF THE LAST IN A SERIES OF MID LEVEL SHORTWAVE TROUGHS EXITS THE AREA. .LONG TERM...SATURDAY THROUGH TUESDAY. DRY CONDITIONS ARE FORECAST THROUGH THE EXTENDED PERIODS. ON SATURDAY...THE PATTERN ALOFT WILL FEATURE A TROUGH MOVING INTO THE PACIFIC NORTHWEST...RIDGING OVER THE ROCKIES AND A LONGWAVE TROUGH FROM THE HUDSON BAY SOUTH TO THE GULF COAST STATES. HEIGHTS WILL RISE ACROSS THE CENTRAL PLAINS OVER THE WEEKEND AS THE WESTERN RIDGE BUILDS ONTO PLAINS AND THE COLD AIRMASS ASSOCIATED WITH THE TROUGH TO THE EAST DEPARTS. THE RIDGE BEGINS TO BREAK DOWN SUNDAY AS AN UPSTREAM TROUGH REACHES THE NORTH CENTRAL ROCKIES. THIS NEXT TROUGH AND ASSOCIATED COLD FRONT CROSSES THE CENTRAL PLAINS SUNDAY NIGHT/MONDAY...BRINGING ANOTHER ROUND OF COLD AIR TO START THE WORKWEEK. TEMPERATURE WISE...TEMPS BEGIN TO RECOVER ON SATURDAY BEHIND THE UPPER TROUGH...THEN SUNDAY WILL BE THE WARMEST OF THE EXTENDED PERIODS WITH THE MILD AIRMASS IN PLACE AHEAD OF THE NEXT APPROACHING COLD FRONT/SYSTEM. HIGHS SUNDAY ARE LOOKING WELL ABOVE NORMAL IN THE 50S...THEN FOLLOWING COLD FROPA TEMPS RETURN CLOSER TO FEBRUARY NORMALS FOR MON/TUES. && .FIRE WEATHER...ALTHOUGH OUTRIGHT CRITICAL FIRE WEATHER THRESHOLDS ARE CURRENTLY NOT FORECAST DURING THE NEXT FEW DAYS...AT LEAST PARTS OF THE CWA BEAR WATCHING FOR SOME ELEVATED TO NEAR-CRITICAL COMBINATIONS OF WIND AND RELATIVE HUMIDITY. STARTING OFF TODAY...WEST-NORTHWEST SUSTAINED WIND SPEEDS WILL AVERAGE 15-20 MPH IN NEARLY ALL AREAS...WITH SPORADIC TO FREQUENT GUSTS TO 25+ MPH EXPECTED. FORTUNATELY...AFTERNOON RELATIVE HUMIDITY VALUES ACROSS MOST OF THE ARE FORECAST TO HOLD SLIGHTLY ABOVE CRITICAL LEVELS IN THE 25-30 PERCENT RANGE. HOWEVER...IT COULD BE A CLOSE CALL ESPECIALLY IN PARTS OF PHILLIPS/ROOKS/OSBORNE COUNTIES IN KANSAS...WHERE RH VALUES COULD EDGE A BIT CLOSER TO 20 PERCENT. WILL INTRODUCE AN ELEVATED FIRE DANGER MENTION INTO THE HAZARDOUS WEATHER OUTLOOK MAINLY FOR THIS AREA. TURNING TO THURSDAY...AS OUTLINED ABOVE STRONG SUSTAINED WINDS AROUND 30 MPH OR HIGHER ARE FORECAST ACROSS NEARLY THE ENTIRE CWA. FORTUNATELY...COOLER TEMPERATURES WILL KEEP AFTERNOON RH PERCENTAGES ABOVE 30 PERCENT ACROSS NEBRASKA ZONES...BUT KS ZONES COULD SEE VALUES CREEP DOWN CLOSER TO 25 PERCENT. BOTTOM LINE IS...WHILE NO MAJOR FIRE DANGER ISSUES ARE ANTICIPATED THESE NEXT FEW DAYS...SOME CAUTION MAY NEED TAKEN...AND HOURLY RELATIVE HUMIDITY TRENDS THESE NEXT FEW AFTERNOONS WILL NEED WATCHED CLOSELY TO MAKE SURE THERE ARE NO SURPRISES DROPPING BELOW 20 PERCENT. && .PREV DISCUSSION... /ISSUED 1126 PM CST TUE FEB 12 2013/ AVIATION...06Z TAF. LOOK FOR VFR CONDITIONS THRU THE TAF PERIOD WITH CLOUDS LIMITED TO MID/HIGH LEVELS. WINDS WILL REMAIN FROM A WESTERLY DIRECTION BEHIND A SURFACE TROUGH. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM/FIRE WEATHER...PFANNKUCH LONG TERM/AVIATION...FAY
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
949 AM EST WED FEB 13 2013 .SYNOPSIS... LOW PRESSURE WILL BE CROSSING THE TENNESSEE VALLEY TO THE MID ATLANTIC TODAY...BUT WEAK HIGH PRESSURE WILL REMAIN OVER THE LOCAL AREA. LOW PRESSURE FROM WESTERN CANADA WILL CROSS THE GREAT LAKES THURSDAY AND FRIDAY AND BRING TEMPERATURES BELOW NORMAL FOR THE WEEKEND. HIGH PRESSURE WILL BE SLOW TO WORK INTO THE CENTRAL LAKES AND OHIO VALLEY LATE IN THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... ONLY MINOR CHANGES HAVE BEEN MADE TO THE GRIDS TO REFLECT CURRENT CONDITIONS. MODELS HINTING THAT THE CLOUD COVER MAY HANG ON A BIT LONGER THAN EARLIER THINKING SO WE LOWERED HIGHS BY A DEGREE OR TWO. PREVIOUS DISCUSSION... PESKY STRATUS TRAPPED UNDER THE INVERSION HAS BEEN DRIFTING EASTWARD ALL NIGHT. MOST OF THE AREA WILL BE CLOUDY TO START THE DAY. AND THESE SHOULD STICK AROUND THROUGH THE MORNING...SCATTERING THIS AFTERNOON. THE HIGH CLOUDS ASSOCIATED WITH THE LOW THAT WILL PASS TO OUR SOUTH REMAINS THIN ON THE NORTHERN EDGE...BUT FOR THE AFTERNOON THEY WILL BE THICKER ACROSS THE SOUTHERN THIRD TO HALF OF THE AREA...THINNER NORTH. THE BEST OUTLOOK FOR SUN WOULD BE FOR NW OH/TOLEDO AREA LATER TODAY. AS WE HAVE HAD THE PAST SEVERAL DAYS...FORECASTING PRECIP TO REMAIN SOUTH OF THE AREA...AND DRY AIR IN PLACE WINNING OUT. TEMPERATURES ARE TOUGH TODAY. HAVE STUCK WITH PREVIOUS FORECAST OF UPPER 30S MOST PLACES. SLIGHTLY COOLER ALONG THE LAKESHORE WITH A LIGHT NORTH FLOW. OVERALL NOT TOO FAR OFF FROM TUESDAYS HIGHS AND FAIRLY CLOSE TO GUIDANCE. NO CHANGES FROM EARLIER. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... A DISSIPATING TROUGH FROM THE NORTHERN LAKES WILL JUST BRUSH THE AREA TONIGHT. THIS WILL GIVE US NO TROUBLE OTHER THAN BRINGING A FEW MID/HIGH CLOUDS ACROSS THE AREA OVERNIGHT. BY MORNING THE RIDGE ACCESS IS TO OUR EAST AND WE HAVE SET UP A LIGHT RETURN FLOW. A LITTLE WEDGE OF WARMER AIR REACHES INTO IND/OH/LOWER MI ON THURSDAY. WILL STICK WITH H8 TEMPS STILL BELOW ZERO...BUT THAT WILL AT LEAST GET US WELL INTO THE 40S FOR HIGHS. LEANED TOWARD THE WARMER GFSBC NUMBERS AS WE SHOULD BE ABLE TO WARM NICELY WITH MID FEB SUN. WITH THE AFTERNOON THOUGH WE GET ONE FRONT AND SOME LIFT THAT MAY GENERATE A FEW LIGHT RAIN SHOWERS. STILL HAVE NOT MOISTENED THE COLUMN SO DID NOT BRING PRECIP CHANCE UP TO 40% OR SO UNTIL LATE IN THE AFTERNOON. THE BETTER COLD FRONT...SURGE OF COLDER AIR...AND BETTER MOISTURE ARRIVES LATE THURSDAY NIGHT. SO LOWS THURSDAY NIGHT STILL REASONABLE IN THE LOWER 30S. FRIDAY THOUGH WE MAY SEE LITTLE RISE AS THE BRUNT OF THE COLD AIR ARRIVES. BASE OF TROUGH MOVES INTO THE OHIO VALLEY SO MUCH OF THE AREA WILL SEE AT LEAST SCATTERED SNOW SHOWERS FRIDAY AND FRIDAY NIGHT WITH SOME LIGHT ACCUMULATIONS. MORE FREQUENT SNOW SHOWERS FOR NE OH/NW PA. SNOW SHOWERS LINGER ACROSS NE OH/NW PA INTO SATURDAY. TEMPS BELOW NORMAL SATURDAY AND EVEN COLDER SATURDAY NIGHT. LOOKING FOR TEENS SATURDAY NIGHT...WITH SOME SINGLE DIGITS POSSIBLE. HIGH WILL BE BUILDING IN FROM THE WEST AT THIS POINT AND MAY HAVE SOME CLEARING WITH IT FOR FDY AREA. && .LONG TERM /SUNDAY THROUGH TUESDAY/... THE THREAT OF SNOW SHOWERS CONTINUES ON SUNDAY OVER THE SNOW BELT. THE LAKE AND 850 MB TEMPERATURE DIFFERENCE WILL BE NEAR 18C...HOWEVER...THE AIRMASS IS VERY DRY...CHANCE POPS SEEM REASONABLE. ELSEWHERE DRY AND PARTLY CLOUDY. HIGH PRESSURE WILL BE MOVING ACROSS THE FORECAST AREA SUNDAY NIGHT. THE FLOW REMAINS NORTHWEST BUT WE ARE IN WARM ADVECTION SUNDAY NIGHT. WILL FORECAST A CHANCE OF FLURRIES FOR THE SNOW BELT. A STRONG LOW WILL MOVE THROUGH THE WESTERN LAKES MONDAY NIGHT INTO TUESDAY. MAJOR MODEL DIFFERENCES IN THE STRENGTH...TIMING AND TRACK OF THE LOW. THIS WILL DETERMINE WHAT THE PRECIPITATION TYPE IS. AT THIS TIME KEPT IT SNOW MONDAY NIGHT AND RAIN OR SNOW TUESDAY...BUT THIS WILL HAVE TO BE MONITORED. IF THE GFS IS CORRECT IT COULD BE RAIN OR FREEZING RAIN MONDAY NIGHT AND MAINLY RAIN ON TUESDAY. USED A BLEND OF GUIDANCE FOR THE TEMPERATURES BUT CONFIDENCE IS LOW WITH THE MODEL DISCREPANCIES. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... HIGH PRESSURE OVER NORTHERN OHIO WILL MOVE EAST TODAY. PLENTY OF LOW LEVEL MOISTURE STUCK UNDER THE INVERSION WITH MVFR CEILINGS FAIRLY WIDESPREAD. ANY AREAS THAT ARE SCATTERED WILL BECOME BROKEN AFTER DAYBREAK. THE QUESTION IS HOW LONG WILL IT TAKE FOR THE LOW CLOUDS TO DECREASE. THE RUC AND LAMP GUIDANCE ARE TRYING TO INDICATE IT WILL TAKE ALL DAY FOR NW PA AND A LARGE PART OF NE OH. THAT SEEMS OVERDONE WITH THE SUN ANGLE GETTING STRONGER AND SOME SUBSIDENCE. WILL TRY DECREASING THE LOW CLOUDS IN THE AFTERNOON. FOR THE SOUTHERN PORTION OF THE FORECAST AREA MID CLOUDS WILL OCCUR BECAUSE OF THE UPPER TROF THAT WAS MOVING THROUGH THE OHIO VALLEY TODAY. THE CLOUDS WILL DECREASE FOR A TIME LATE THIS AFTERNOON THROUGH EARLY TONIGHT...THEN THEY WILL INCREASE AHEAD OF THE NEXT SYSTEM. OUTLOOK...NON-VFR THURSDAY NIGHT AND FRIDAY SHIFTING TO MAINLY THE SNOWBELT SATURDAY NIGHT AND SUNDAY. && .MARINE... OCCASIONAL WEATHER SYSTEMS WILL MOVE THROUGH THE REGION DURING THE PERIOD. HIGH PRESSURE WILL BE OVER THE LAKE THIS MORNING AND THEN IT WILL MOVE EAST. A FRONTAL SYSTEM WILL MOVE ACROSS LAKE ERIE THURSDAY NIGHT. WILL HAVE TO KEEP AN EYE ON THE WINDS...THE COLD ADVECTION IS SOMEWHAT WEAK. THE GFS MODEL HAS THE 925 MB WINDS UP TO 40 KTS...TRYING TO FLIRT WITH GALE FORCE WINDS. HOWEVER...THE NAM MODEL AND THE ECMWF ARE MUCH WEAKER. THIS WILL HAVE TO BE MONITORED. AT THIS TIME KEPT THE WINDS IN THE 15 TO 25 KNOT RANGE. FOR FRIDAY THROUGH SUNDAY THE FLOW WILL BE NORTHWEST WITH PLENTY OF COLD AIR BUT THE WINDS WILL STAY WELL BELOW GALE FORCE SPEEDS. HIGH PRESSURE BUILDS IN BRIEFLY SUNDAY NIGHT AND THEN A STRONG SOUTHERLY FLOW DEVELOPS. THE WEATHER SYSTEM FOR MONDAY NIGHT INTO TUESDAY COULD HAVE NEAR GALE FORCE WINDS DEPENDING ON THE TRACK OF THE LOW. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...OUDEMAN NEAR TERM...MULLEN/OUDEMAN SHORT TERM...OUDEMAN LONG TERM...KIELTYKA AVIATION...KIELTYKA MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
650 AM EST WED FEB 13 2013 .SYNOPSIS... LOW PRESSURE WILL BE CROSSING THE TENNESSEE VALLEY TO THE MID ATLANTIC TODAY...BUT WEAK HIGH PRESSURE WILL REMAIN OVER THE LOCAL AREA. LOW PRESSURE FROM WESTERN CANADA WILL CROSS THE GREAT LAKES THURSDAY AND FRIDAY AND BRING TEMPERATURES BELOW NORMAL FOR THE WEEKEND. HIGH PRESSURE WILL BE SLOW TO WORK INTO THE CENTRAL LAKES AND OHIO VALLEY LATE IN THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... PESKY STRATUS TRAPPED UNDER THE INVERSION HAS BEEN DRIFTING EASTWARD ALL NIGHT. MOST OF THE AREA WILL BE CLOUDY TO START THE DAY. AND THESE SHOULD STICK AROUND THROUGH THE MORNING...SCATTERING THIS AFTERNOON. THE HIGH CLOUDS ASSOCIATED WITH THE LOW THAT WILL PASS TO OUR SOUTH REMAINS THIN ON THE NORTHERN EDGE...BUT FOR THE AFTERNOON THEY WILL BE THICKER ACROSS THE SOUTHERN THIRD TO HALF OF THE AREA...THINNER NORTH. THE BEST OUTLOOK FOR SUN WOULD BE FOR NW OH/TOLEDO AREA LATER TODAY. AS WE HAVE HAD THE PAST SEVERAL DAYS...FORECASTING PRECIP TO REMAIN SOUTH OF THE AREA...AND DRY AIR IN PLACE WINNING OUT. TEMPERATURES ARE TOUGH TODAY. HAVE STUCK WITH PREVIOUS FORECAST OF UPPER 30S MOST PLACES. SLIGHTLY COOLER ALONG THE LAKESHORE WITH A LIGHT NORTH FLOW. OVERALL NOT TOO FAR OFF FROM TUESDAYS HIGHS AND FAIRLY CLOSE TO GUIDANCE. NO CHANGES FROM EARLIER. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... A DISSIPATING TROUGH FROM THE NORTHERN LAKES WILL JUST BRUSH THE AREA TONIGHT. THIS WILL GIVE US NO TROUBLE OTHER THAN BRINGING A FEW MID/HIGH CLOUDS ACROSS THE AREA OVERNIGHT. BY MORNING THE RIDGE ACCESS IS TO OUR EAST AND WE HAVE SET UP A LIGHT RETURN FLOW. A LITTLE WEDGE OF WARMER AIR REACHES INTO IND/OH/LOWER MI ON THURSDAY. WILL STICK WITH H8 TEMPS STILL BELOW ZERO...BUT THAT WILL AT LEAST GET US WELL INTO THE 40S FOR HIGHS. LEANED TOWARD THE WARMER GFSBC NUMBERS AS WE SHOULD BE ABLE TO WARM NICELY WITH MID FEB SUN. WITH THE AFTERNOON THOUGH WE GET ONE FRONT AND SOME LIFT THAT MAY GENERATE A FEW LIGHT RAIN SHOWERS. STILL HAVE NOT MOISTENED THE COLUMN SO DID NOT BRING PRECIP CHANCE UP TO 40% OR SO UNTIL LATE IN THE AFTERNOON. THE BETTER COLD FRONT...SURGE OF COLDER AIR...AND BETTER MOISTURE ARRIVES LATE THURSDAY NIGHT. SO LOWS THURSDAY NIGHT STILL REASONABLE IN THE LOWER 30S. FRIDAY THOUGH WE MAY SEE LITTLE RISE AS THE BRUNT OF THE COLD AIR ARRIVES. BASE OF TROUGH MOVES INTO THE OHIO VALLEY SO MUCH OF THE AREA WILL SEE AT LEAST SCATTERED SNOW SHOWERS FRIDAY AND FRIDAY NIGHT WITH SOME LIGHT ACCUMULATIONS. MORE FREQUENT SNOW SHOWERS FOR NE OH/NW PA. SNOW SHOWERS LINGER ACROSS NE OH/NW PA INTO SATURDAY. TEMPS BELOW NORMAL SATURDAY AND EVEN COLDER SATURDAY NIGHT. LOOKING FOR TEENS SATURDAY NIGHT...WITH SOME SINGLE DIGITS POSSIBLE. HIGH WILL BE BUILDING IN FROM THE WEST AT THIS POINT AND MAY HAVE SOME CLEARING WITH IT FOR FDY AREA. && .LONG TERM /SUNDAY THROUGH TUESDAY/... THE THREAT OF SNOW SHOWERS CONTINUES ON SUNDAY OVER THE SNOW BELT. THE LAKE AND 850 MB TEMPERATURE DIFFERENCE WILL BE NEAR 18C...HOWEVER...THE AIRMASS IS VERY DRY...CHANCE POPS SEEM REASONABLE. ELSEWHERE DRY AND PARTLY CLOUDY. HIGH PRESSURE WILL BE MOVING ACROSS THE FORECAST AREA SUNDAY NIGHT. THE FLOW REMAINS NORTHWEST BUT WE ARE IN WARM ADVECTION SUNDAY NIGHT. WILL FORECAST A CHANCE OF FLURRIES FOR THE SNOW BELT. A STRONG LOW WILL MOVE THROUGH THE WESTERN LAKES MONDAY NIGHT INTO TUESDAY. MAJOR MODEL DIFFERENCES IN THE STRENGTH...TIMING AND TRACK OF THE LOW. THIS WILL DETERMINE WHAT THE PRECIPITATION TYPE IS. AT THIS TIME KEPT IT SNOW MONDAY NIGHT AND RAIN OR SNOW TUESDAY...BUT THIS WILL HAVE TO BE MONITORED. IF THE GFS IS CORRECT IT COULD BE RAIN OR FREEZING RAIN MONDAY NIGHT AND MAINLY RAIN ON TUESDAY. USED A BLEND OF GUIDANCE FOR THE TEMPERATURES BUT CONFIDENCE IS LOW WITH THE MODEL DISCREPANCIES. && .AVIATION /11Z WEDNESDAY THROUGH SUNDAY/... HIGH PRESSURE OVER NORTHERN OHIO WILL MOVE EAST TODAY. PLENTY OF LOW LEVEL MOISTURE STUCK UNDER THE INVERSION WITH MVFR CEILINGS FAIRLY WIDESPREAD. ANY AREAS THAT ARE SCATTERED WILL BECOME BROKEN AFTER DAYBREAK. THE QUESTION IS HOW LONG WILL IT TAKE FOR THE LOW CLOUDS TO DECREASE. THE RUC AND LAMP GUIDANCE ARE TRYING TO INDICATE IT WILL TAKE ALL DAY FOR NW PA AND A LARGE PART OF NE OH. THAT SEEMS OVERDONE WITH THE SUN ANGLE GETTING STRONGER AND SOME SUBSIDENCE. WILL TRY DECREASING THE LOW CLOUDS IN THE AFTERNOON. FOR THE SOUTHERN PORTION OF THE FORECAST AREA MID CLOUDS WILL OCCUR BECAUSE OF THE UPPER TROF THAT WAS MOVING THROUGH THE OHIO VALLEY TODAY. THE CLOUDS WILL DECREASE FOR A TIME LATE THIS AFTERNOON THROUGH EARLY TONIGHT...THEN THEY WILL INCREASE AHEAD OF THE NEXT SYSTEM. OUTLOOK...NON-VFR THURSDAY NIGHT AND FRIDAY SHIFTING TO MAINLY THE SNOWBELT SATURDAY NIGHT AND SUNDAY. && .MARINE... OCCASIONAL WEATHER SYSTEMS WILL MOVE THROUGH THE REGION DURING THE PERIOD. HIGH PRESSURE WILL BE OVER THE LAKE THIS MORNING AND THEN IT WILL MOVE EAST. A FRONTAL SYSTEM WILL MOVE ACROSS LAKE ERIE THURSDAY NIGHT. WILL HAVE TO KEEP AN EYE ON THE WINDS...THE COLD ADVECTION IS SOMEWHAT WEAK. THE GFS MODEL HAS THE 925 MB WINDS UP TO 40 KTS...TRYING TO FLIRT WITH GALE FORCE WINDS. HOWEVER...THE NAM MODEL AND THE ECMWF ARE MUCH WEAKER. THIS WILL HAVE TO BE MONITORED. AT THIS TIME KEPT THE WINDS IN THE 15 TO 25 KNOT RANGE. FOR FRIDAY THROUGH SUNDAY THE FLOW WILL BE NORTHWEST WITH PLENTY OF COLD AIR BUT THE WINDS WILL STAY WELL BELOW GALE FORCE SPEEDS. HIGH PRESSURE BUILDS IN BRIEFLY SUNDAY NIGHT AND THEN A STRONG SOUTHERLY FLOW DEVELOPS. THE WEATHER SYSTEM FOR MONDAY NIGHT INTO TUESDAY COULD HAVE NEAR GALE FORCE WINDS DEPENDING ON THE TRACK OF THE LOW. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...OUDEMAN NEAR TERM...OUDEMAN SHORT TERM...OUDEMAN LONG TERM...KIELTYKA AVIATION...KIELTYKA MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
938 AM EST WED FEB 13 2013 .DISCUSSION...14Z SURFACE MAP SHOWS LOW PRESSURE NOW CENTERED OVER SW VA...AND THIS SURFACE LOW SHOULD TRACK NE OVER THE NEXT FEW HOURS. MAIN AREA OF REMAINING LIGHT RAIN SHOWERS HAS LIFTED NORTH OF THE SRN 2/3RDS OF THE FORECAST AREA. LATEST RUC MODEL RUN SHOWS GOOD COVERAGE OF LIGHT RAIN OVER NRN PLATEAU...EXTREME NE TN AND SW VA THIS AFTERNOON...AS SOME RAIN WRAPS AROUND ON THE BACK SIDE OF THE EXITING LOW PRESSURE SYSTEM. PLAN TO UPDATE FORECAST GRIDS SHORTLY...AND I MAY NEED TO LOWER RAIN CHANCES ACROSS SE TN AND SW NC BY AT LEAST 20 PERCENT. WILL KEEP HIGH LIKELY TO LOW CATEGORICAL CHANCES OVER NRN PARTS OF E TN INTO SW VA. HOURLY TEMPS ARE RUNNING VERY CLOSE TO GRIDS AND MAX TEMPS APPEAR ON TRACK. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 52 33 57 35 54 / 70 10 10 10 10 KNOXVILLE MCGHEE TYSON AIRPORT, TN 47 32 54 34 50 / 90 20 10 10 20 OAK RIDGE, TN 47 32 54 33 50 / 90 20 10 10 10 TRI CITIES AIRPORT, TN 46 29 50 31 47 / 90 40 10 10 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ TG
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
345 PM MST WED FEB 13 2013 .SHORT TERM...MODERATE NORTHWEST FLOW ALOFT ACROSS REGION. AIRMASS FAIRLY MOIST BUT RELATIVELY STABLE. MOUNTAIN WEB CAMS SHOWING SOME LIGHT SNOW ALONG THE CONTINENTAL DIVIDE AS THE PARK AND GORE RANGES OF WESTERN JACKSON COUNTY. LATEST SNOTEL DATA SUGGESTING SOME LIGHT ACCUMULATIONS IN ZONE 31 AND PORTIONS OF ZONES 33 AND 34. WINDS HAVE BEEN A BIT GUSTY ACROSS THE HIGHER RIDGES AND ALONG THE FOOTHILLS. WEST TO NORTHWEST WINDS HAVE ALSO SPREAD ONTO THE ADJACENT PLAINS AS WELL AS ALONG THE WYOMING AND NEBRASKA BORDERS. LATEST RAP SHOWS MOISTURE GRADUALLY INCREASING AS LAPSE RATES INCREASE TO AROUND 7 C/KM BY MIDNIGHT. SHOULD SEE THE SNOW INCREASE IN COVERAGE OVERNIGHT DUE TO FAVORABLE OROGRAPHICS AND LAPSE RATES...MAINLY NORTH OF INTERSTATE 70. THERE IS ALSO SOME INCREASE IN MID LEVEL QG ASCENT AHEAD OF AN APPROACHING SHORTWAVE WHICH WILL HELP WITH SNOWFALL. SNOW ACCUMULATIONS SHOULD REMAIN BELOW ADVISORY CRITERIA. ACROSS FOOTHILLS AND PLAINS...GRADIENT WEAKENS DURING THE EVENING. SHOULD SEE WINDS DECREASE AS A RESULT...WITH DRAINAGE PATTERN PREVAILING. ON THURSDAY...NORTHWEST FLOW ALOFT TO CONTINUE. MODELS CONTINUE TO SHOW WEAK SHORTWAVE MOVING ACROSS WYOMING DURING THE AFTERNOON WITH MID LEVEL ASCENT MOVING OVER THE AREA. LIGHT SNOW TO BE MORE WIDESPREAD OVER THE MOUNTAINS SOUTH OF INTERSTATE 70 BY THE AFTERNOON AS OROGRAPHICS REMAINS FAVORABLE. MODEL CROSS SECTIONS INDICATE VARYING AMOUNTS OF MOISTURE WITH THE GFS DEEPEST. WILL INCREASE THE POPS AND COVERAGE OF THE SNOW A BIT BUT KEEP AMOUNTS BELOW ADVISORY CRITERIA. ACROSS PLAINS...MODELS CONTINUE TO SHOW A FRONT MOVING SOUTH ACROSS THE AREA DURING THE MORNING...REACHING DENVER AREA AROUND 15-18Z. NORTHERLY WINDS WITH FRONT BECOMES NORTHEAST DURING THE AFTERNOON AS SURFACE HIGH PUSHES IN BEHIND FRONT. UPSLOPE NOT ALL THAT DEEP ACCORDING TO THE CROSS SECTIONS BUT DOES REACH THE FOOTHILLS. MODELS DO INDICATE SOME LIGHT QPF IN AND NEAR FOOTHILLS DURING THE AFTERNOON WHEN THE UPSLOPE FLOW OCCURS AND LIFT IS OVERHEAD. MODEL CONCENSUS SHOWING SNOW AMOUNTS TO BE LESS THAN AN INCH AND CONFINED TO FOOTHILL AREAS. GFS CONTINUES TO BE AGRESSIVE WITH THE QPF AND SNOW AMOUNTS. WILL CONTINUE WITH THE CHANCE POPS FOR THE AFTERNOON MOST AREAS...WITH LIKELY POPS FOR THE FOOTHILLS. TEMPERATURES TO BE COOLER WITH HIGHS IN THE LOWER TO MID 30S ACROSS THE PLAINS. .LONG TERM...NORTHWEST FLOW ALOFT WILL PREVAIL THURSDAY NIGHT AND FRIDAY WHILE NORTHERLY FLOW EXISTS AT THE LOWER LEVELS. MOISTURE...LIFT AND INSTABILITY WILL BE LIMITED...BUT ENOUGH WILL BE PRESENT FOR OCCASIONAL LIGHT SNOW. A WEAK SHORT WILL MOVE ACROSS THE STATE FRIDAY. IN ADDITION...THE FRONT LEFT QUADRANT OF THE JET WILL BE OVER NORTHEAST COLORADO FRIDAY. THESE FEATURES WILL PROVIDE THE LIFT FOR THE LIGHT SNOW. SNOW WILL COME TO END BY FRIDAY EVENING...IF NOT SOONER AS DRIER AIR SHIFTS OVER THE STATE. UPPER LEVEL RIDGE WILL MOVE OVER COLORADO SATURDAY. AN UPPER LEVEL TROUGH WILL DROP INTO THE NORTHERN ROCKIES SUNDAY CAUSING FLOW ALOFT TO BECOME WESTERLY ON SUNDAY. THIS WILL RESULT IN MILD AND DRY CONDITIONS FOR THE WEEKEND WITH HIGHS IN THE 50S ACROSS NORTHEAST COLORADO. FOR SUNDAY NIGHT AND MONDAY...THE SHORT WAVE TROUGH OVER THE NORTHERN ROCKIES MAY BRING THE AREA A ROUND OF SNOW AS IT PROGRESSES EAST. THE GFS BRINGS A PIECE OF ENERGY THROUGH UTAH AND THEN DROPS IT SOUTHEAST INTO NEW MEXICO. THE ECMWF KEEPS THIS SYSTEM NORTH OF COLORADO WHICH WOULD RESULT IN DRY CONDITIONS. THE CMC IS SIMILAR TO THE ECMWF SO WILL KEEP POPS ON THE LOW END FOR THIS SYSTEM. STILL EXPECT A COLD FRONT AND COOLER AIR TO PUSH THROUGH COLORADO IF THIS SYSTEMS STAYS NORTH OF THE STATE. UPPER LEVEL RIDGE WILL QUICKLY MOVE ACROSS THE STATE MONDAY NIGHT AND BY TUESDAY A SOUTHWEST FLOW ALOFT WILL PREVAIL AS A LARGE TROUGH CRASHES ONTO THE WEST COAST. THIS SYSTEM WILL SLOWLY MOVE EASTWARD WEDNESDAY. EXPECT MILD AND DRY CONDITIONS TO PREVAIL WEDNESDAY AHEAD OF THIS SYSTEM. MAY BE ENOUGH MOISTURE AHEAD OF IT TO PRODUCE LIGHT MOUNTAIN SNOW. LOOKING BEYOND THE FORECAST TIME FRAME...THE PAST TWO RUNS OF THE ECMWF SHOW THIS TROUGH MOVING ALONG THE COLORADO/NEW MEXICO BORDER. IF THIS TYPE OF PATTERN PREVAILS...EASTERN COLORADO COULD SEE A GOOD SHOT OF SNOW. && .AVIATION...WEST TO NORTHWEST WINDS HAVE PUSHED ACROSS THE AREA AIRPORTS DURING THE AFTERNOON...WITH GUSTS AROUND 35 KTS AT APA AND BJC. WINDS SHOWING MORE OF A WESTERLY COMPONENT IN THE PAST HOUR. MODELS SHOW WINDS WEAKENING BY 01Z AND BECOMING MORE SOUTHWEST AS DRAINAGE FLOW DEVELOPS. MID AND HIGH LEVEL LEVEL MOISTURE TO INCREASE OVERNIGHT...CEILINGS TO REMAIN ABOVE 10000 FEET. ON THURSDAY...FRONT TO MOVE ACROSS THE AREA AROUND 15Z WITH WINDS SHIFTING TO THE NORTH. COULD SEE SOME GUSTS TO 30 KTS. CEILINGS EXPECTED TO LOWER TO AROUND 6000 FEET AGL BY 18Z. A FEW SNOW SHOWERS COULD DEVELOP DURING THE MORNING...MAINLY WESTERN SUBURBS. NORTHEAST WINDS DEVELOP AFTER 18Z WITH MVFR CEILINGS POSSIBLE. THERE WILL BE A CHANCE OF LIGHT SNOW DURING THE AFTERNOON...FOR NOW WILL WILL MAINTAIN A PROB30. ANY ACCUMULATIONS SHOULD BE LESS THAN AN INCH. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....MEIER AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1009 AM MST WED FEB 13 2013 .UPDATE... && .SHORT TERM...CURRENT FORECASTS LOOK REASONABLE. MOUNTAIN WEB CAMS INDICATING SOME LIGHT SNOW OVER THE HIGHER PEAKS OF SUMMIT... GRAND AND BOULDER COUNTIES...WITH PERHAPS SOME LIGHT SNOW ACROSS THE PARK AND GORE RANGES OF WESTERN JACKSON COUNTY. WINDS HAVE BEEN STEADILY INCREASING ACROSS THE HIGHER MOUNTAINS AND FOOTHILLS... LATEST 1500 MB GJT-DEN PRESSURE GRADIENT HAD INCREASED TO 10.40 MB. GUSTS WERE MAINLY IN THE 40-50 MPH RANGE ALONG THE FOOTHILLS OF BOULDER...JEFFERSON AND LARIMER COUNTIES. LATEST RAP CROSS SECTIONS INDICATE CROSS MOUNTAIN FLOW AROUND 35 KTS ALONG WITH A WEAK STABLE LAYER NEAR THE MOUNTAIN TOP THROUGH THE AFTERNOON. AT THIS TIME... NOT EXPECTING WINDS TO REACH HIGH WIND CRITERIA. COVERAGE OF SNOW TO INCREASE AFTER MIDNIGHT WHEN LAPSE RATES INCREASE AND OROGRAPHICS BECOME MORE FAVORABLE. .AVIATION...WESTERLIES SLOW TO PUSH INTO THE DENVER AREA...FINALLY REACHED BJC. RECENTLY DELAYED THE ONSET OF THE WEST WINDS AT DEN TIL 19Z. THIS STILL SEEMS ON TRACK AS LATEST DEN LLWAS DATA CONTINUES TO INDICATE MORE OF A SOUTHWEST DIRECTION. LATEST RAP AND HRRR SHOW WINDS BECOMING NORTHWEST AT DEN AND APA BY 21Z. SO TREND FOR NORTHWEST WINDS STILL LOOKS REASONABLE...BUT WILL DELAY THE ONSET FOR THE UPCOMING ISSUANCE. REST OF TAF TRENDS SEEM REASONABLE...WITH SOUTH TO SOUTHWEST DRAIANGE WINDS DEVELOPING DURING THE EVENING. COLD FRONT STILL ON TRACK TO MOVE ACROSS THE AREA AIRPORTS AROUND 15Z THURSDAY...WITH NORTHEAST WINDS DEVELOPING ALONG WITH LOWER CEILINGS. WILL INCLUDE A PROB30 AT DEN AFTER 19Z WITH MVFR CEILINGS. && .PREV DISCUSSION... /ISSUED 301 AM MST WED FEB 13 2013/ SHORT TERM...NW FLOW ALOFT WILL INCREASE OVER THE AREA THRU TONIGHT WITH MOISTURE GRADUALLY INCREASING IN THE MTNS. ALTHOUGH OROGRAPHIC FLOW WILL BE FAVORABLE LAPSE RATES INITIALLY ARE RATHER STABLE AND REALLY DO NOT BEGIN TO INCREASE UNTIL AFTER MIDNIGHT. THUS EXPECT AREAS OF LIGHT SNOW IN THE MTNS MAINLY NORTH OF I-70 WITH SOME INCREASE IN COVERAGE TONIGHT. OVERALL AMOUNTS AT LEAST THRU TONIGHT STAY BLO ADVISORY CRITERIA. MEANWHILE WITH MTN TOP STABILITY THRU THE AFTN HOURS WILL SEE GUSTY WINDS OVER THE HIGHER MTNS AND IN AND NR THE FOOTHILLS. COMPONENT ALONG SPEEDS ARE ON AVERAGE AROUND 35KTS SO SPEEDS SHOULD STAY BLO HIGH WIND CRITERIA. WILL ALSO SEE GUSTY WINDS NR THE WY-NE BORDER AS WELL THRU THE AFTN HOURS. AS FOR TEMPS OVER NERN CO WILL HAVE HIGHS IN THE 45 TO 50 DEGREE RANGE. LONG TERM...MODELS HAVE FAIRLY STRONG WEST-NORTHWESTERLY FLOW ALOFT FOR THE CWA THURSDAY. BY LATE IN THE DAY A WEAK UPPER TROUGH PUSHES ACROSS WITH STRONG NORTH-NORTHWESTERLY FLOW ALOFT BEHIND IT. THE STRONG FLOW ALOFT IS PROGGED TO CONTINUE ON FRIDAY...BUT TO BECOME NORTHERLY IN DIRECTION. THE FLOW ALOFT BECOMES NORTHWESTERLY AND RELAXES SOMEWHAT BY 12Z SATURDAY MORNING. THE QG VERTICAL VELOCITY FIELDS SHOW WEAK UPWARD ENERGY THURSDAY...FOLLOWED BY DOWNWARD MOTION LATE DAY INTO THE EVENING...THEN ANOTHER BRIEF SHOT OF UPWARD MOTION THROUGH 12Z FRIDAY MORNING. AFTER THAT IT IS ALL DOWNWARD MOTION INTO THE WEEKEND. THE UPWARD MOTION LOOKED BETTER ON YESTERDAY`S 00Z RUNS. THE BOUNDARY LAYER FLOW PROGGS STILL SHOW A BIT OF UPSLOPE OVER THE PLAINS ON THURSDAY...BUT IT IS GONE THURSDAY NIGHT. BY FRIDAY MORNING...DOWNSLOPING NORTHWESTERLY FLOW IS PROGGED CONTINUING THROUGH FRIDAY NIGHT. AGAIN...YESTERDAY`S 00Z RUNS HAD BETTER AND MORE PROLONGED UPSLOPE FOR PLAINS AND FOOTHILLS. MOISTURE IS ALSO LESS ACCORDING TO THE CURRENT MODEL RUNS...ESPECIALLY ON THE NAM. THERE IS SOME MOISTURE AROUND ON THE NAM THURSDAY...BUT IT DECREASES PRETTY GOOD THURSDAY EVENING. IT INCREASES AGAIN BY 12Z FRIDAY MORNING...THEN GRADUALLY DECREASES THROUGH THE DAY FRIDAY. THE GFS HAS A SIMILAR PATTERN ALTHOUGH THE DEPTH OF MOISTURE IS GREATER THAN ON THE NAM. THE ECMWF IS SOMEWHERE IN BETWEEN THE TWO. FRIDAY NIGHT DRIES OUT PRETTY GOOD ON ALL THE MODELS. THE QPF FIELDS SHOW MEASURABLE SNOWFALL FOR THE CWA THURSDAY INTO FRIDAY. IT IS LESS THAN YESTERDAY`S RUNS INDICATED AND IT IS MOSTLY OVER THE THE MOUNTAINS. AMOUNTS ARE PRETTY WEAK. SO FOR POPS IN THE MOUNTAINS...THERE WILL BE SOME OROGRAPHIC HELP AND THERE IS SOME MOISTURE...SO WILL GO WITH "LIKELY"S THURSDAY AND THURSDAY NIGHT...THEN DECREASE POPS TO NOTHING DURING THE EVENING FRIDAY. FOR THE PLAINS...10-40%S SHOULD THURSDAY AFTERNOON INTO MIDDAY FRIDAY. ACCUMULATIONS IN THE MOUNTAINS LOOK TO BE UNDER ADVISORY AMOUNTS. FOR TEMPERATURES...THURSDAY`S HIGHS SHOULD BE 4-8 C COLDER THAN TODAY`S HIGHS. FRIDAY`S HIGHS ARE 0-3 C WARMER THAN THURSDAY`S. FOR THE LATER DAY`S...SATURDAY THROUGH TUESDAY... MODELS HAVE DECREASING NORTHWESTERLY FLOW ALOFT ON SATURDAY AS AN UPPER RIDGE MOVES IN AND ACROSS THE CWA BY SUNDAY. THE NEXT UPPER TROUGH GETS INTO WESTERN COLORADO BY 12Z MONDAY AND ACROSS THE CWA BY EARLY MONDAY EVENING. DECREASING NORTHWESTERLY FLOW ALOFT MONDAY NIGHT GIVES WAY TO ANOTHER UPPER RIDGE ON TUESDAY. THE LATE SUNDAY NIGHT THROUGH LATE MONDAY TROUGH LOOKS TO HAVE OK MOISTURE ..FAIR COLD AIR...AND UPSLOPE FOR THE PLAINS AND FOOTHILLS. WE`LL SEE. AVIATION...EARLY THIS MORNING WINDS WERE DRAINAGE WITH A BKN DECK AROUND 9000 FT. SATELLITE ALREADY SHOWS THIS BKN DECK MOVING SE SO SKIES SHOULD ONLY SEE SOME HIGHER CLOUDS. BY LATE THIS MORNING INTO THE EARLY AFTN THE GUSTY WNW WINDS NR THE FOOTHILLS LOOK LIKE THEY WILL GRADUALLY SPREAD ACROSS THE AIRPORT WITH SOME GUSTS TO 20-25 POSSIBLE FM 19Z-23Z BEFORE DECREASING. BY EARLY THIS EVENING WILL KEEP THEM MORE WSW AND THEN SSW BY 06Z. WILL SEE SOME HIGHER LEVEL CLOUD COVER THIS AFTN AND TONIGHT BUT NOTHING BLO 20000 FT. A CDFNT WILL MOVE INTO THE AREA BY 15Z ON THU WITH WINDS BECOMING NNE ALONG WITH LOWER CEILINGS DEVELOPING. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....RJK AVIATION...D-L
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
226 PM EST WED FEB 13 2013 .SYNOPSIS... LOW PRESSURE WILL BE LIFTING NORTHEAST OF THE FORECAST AREA THROUGH TONIGHT. THE PRESSURE GRADIENT WILL RELAX AND WINDS WILL DIMINISH TONIGHT AS THE LOW MOVES FARTHER AWAY. WEAK HIGH PRESSURE WILL DOMINATE THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... THIS AFTERNOON...LOW PRESSURE IS LIFTING NORTHEAST OF THE AREA. THE PRESSURE GRADIENT ASSOCIATED WITH THIS LOW WILL BRING BREEZY CONDITIONS. THE NAM BUFKIT MOMENTUM TRANSFER INDICATED GUSTS OF 25 TO 30 KNOTS. THE HRRR INDICATED GUSTS OF 30 TO 35 KNOTS OVER MUCH OF THE AREA THIS AFTERNOON. OBSERVATION TRENDS SUPPORT THESE WIND GUSTS. A LAKE WIND ADVISORY REMAINS IN EFFECT. AN AREA OF CONVERGENCE WAS SUPPORTING A BROKEN LINE OF SHOWERS IN THE FORECAST AREA. THIS LINE SHOULD MOVE OUT OF THE AREA LATER THIS AFTERNOON AND EXPECT COVERAGE WILL REMAIN LIMITED BY ISENTROPIC DOWNGLIDE. TONIGHT...THE LOW WILL BE SHIFTING FARTHER NORTHEAST OF THE AREA WITH A DIMINISHING PRESSURE GRADIENT AND WIND. MODEL TIME SECTIONS SHOW FURTHER LOW-LEVEL DRYING. HIGH CLOUDINESS ASSOCIATED WITH AN UPPER-LEVEL SPEED MAXIMUM WILL SHIFT EASTWARD TONIGHT. WE USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... THE NAM AND GFS SHOW WEAK RIDGING DOMINATING THURSDAY INTO FRIDAY. A REINFORCING DRY COLD FRONT APPEARS TO CROSS THE AREA FRIDAY AFTERNOON AND EVENING. THE GUIDANCE TEMPERATURES WERE CLOSE. && .LONG TERM /SATURDAY THROUGH TUESDAY/... THE GFS AND ECMWF SHOW DEEP AND PROGRESSIVE TROUGHING SATURDAY AND SUNDAY. THERE HAVE BEEN MODEL DIFFERENCES WITH THE AMOUNT OF MOISTURE ASSOCIATED WITH A SHORTWAVE TROUGH LATE SATURDAY...BUT GENERALLY THE MESSAGE HAS BEEN LIMITED MOISTURE AND DOWNSLOPE FLOW. THE MOS POPS FROM THE GFS AND ECMWF FOR THIS PERIOD OVER THE PAST FEW DAYS HAVE BEEN LOW. WE HAVE MAINTAINED THE DRY FORECAST. THE MODELS AGREE SHOWING HIGH MOISTURE TUESDAY ASSOCIATED WITH A COLD FRONT. THE GFS AND ECMWF MOS SUPPORT BELOW NORMAL TEMPERATURES SATURDAY THROUGH MONDAY...AND NEAR NORMAL DURING THE REST OF THE MEDIUM-RANGE PERIOD. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... A WEAK LOW PRESSURE SYSTEM WILL SLOWLY LIFT NORTH OF THE AREA THIS AFTERNOON. A COLD FRONT WILL MOVE THROUGH BY EARLY THIS EVENING. AS THE WARM FRONT LIFTS NORTH OF THE AREA CONDITIONS WILL IMPROVE AND AS LOW CLOUDS BEGIN TO LIFT DURING THE 19Z-21Z TIME PERIOD. A FEW SPRINKLES MAY STILL BE POSSIBLE AT THIS TIME. DEEP MIXING WITHIN AN INCREASING PRESSURE GRADIENT/COLD FRONTAL PASSAGE FROM THE WEST...WILL RESULT IN STRONG SOUTHWEST TO WESTERLY WINDS WITH GUSTS TO 25 KNOTS. WINDS WILL SUBSIDE BY EARLY THIS EVENING...WITH SKIES BECOMING CLEAR DURING THE OVERNIGHT HOURS. HIGH PRESSURE WILL BUILD OVER THE AREA THURSDAY. EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION EXPECTED. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR SCZ015-016- 018-020>022-025>031-035>038-041. GA...LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR GAZ040- 063>065-077. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1235 PM EST WED FEB 13 2013 .SYNOPSIS... LOW PRESSURE WILL BE LIFTING NORTHEAST OF THE FORECAST AREA THIS AFTERNOON AND TONIGHT. WEAK HIGH PRESSURE WILL DOMINATE THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... LOW PRESSURE CENTERED NEAR THE FORECAST AREA WAS SUPPORTING AREAS OF LIGHT RAIN AND DRIZZLE. LATER TODAY...THE LOW WILL BE FARTHER NORTH OF THE AREA AND ISENTROPIC DOWNGLIDE WILL BECOME DOMINATE. THE RAIN CHANCE SHOULD DECREASE. THE NAM AND GFS INDICATED H85 WINDS OF 40 TO 50 KNOTS AND THE KCAE 88D HAS VERIFIED THESE WINDS. THE MODELS SHOWED THIS WIND CONTINUING FOR MUCH OF THE DAY...THEN DIMINISHING LATE TODAY AND TONIGHT. LINGERING CLOUDINESS SHOULD LIMIT MIXING...BUT WITH THE DRYING IN THE AFTERNOON IT SHOULD BECOME BREEZY. THE NAM MOMENTUM TRANSFER INDICATED A POTENTIAL FOR GUSTS NEAR 30 KNOTS. THE HRRR INDICATED WIND GUSTS OF 25 TO 30 KNOTS DEVELOPING IN THE SOUTH PART AROUND 100 PM...WITH GUSTS OF 30 TO 35 KNOTS OVER MUCH OF THE REMAINING AREA BEGINNING AROUND 300 PM. WE HAVE POSTED A LAKE WIND ADVISORY. MODEL TIME SECTIONS SHOW FURTHER DRYING OVERNIGHT AND EXPECT SKIES WILL BECOME CLEAR. WE USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... THE NAM AND GFS SHOW WEAK RIDGING DOMINATING THURSDAY INTO FRIDAY. A REINFORCING DRY COLD FRONT APPEARS TO CROSS THE AREA FRIDAY AFTERNOON AND EVENING. GUIDANCE AND LOCAL NUMBERS ARE VERY CLOSE THROUGH THE PERIOD. && .LONG TERM /SATURDAY THROUGH TUESDAY/... ALL OF THE MODELS SHOW A DEEP...PROGRESSIVE...TROUGH ACROSS THE EASTERN HALF OF THE COUNTRY SATURDAY. THE ECMWF AND GFS DIFFER ON THE SPEED AND STRENGTH OF ADDITIONAL UPPER-LEVEL ENERGY MOVING THROUGH THE TROUGH AND EVENTUALLY HELPING TO LIFT THE TROUGH TO THE EAST AND NORTHEAST BY SUNDAY OR MONDAY. THE GFS DEVELOPS LOW PRESSURE OFF THE MID ATLANTIC COAST SATURDAY AND IS FASTER. THE SLOWER ECMWF...DEVELOPS LOW PRESSURE OFF THE CAROLINA COAST SATURDAY NIGHT AND SUNDAY MORNING. AT THIS TIME...WILL KEEP THE FORECAST DRY FOR THE WEEKEND. THIS WILL BE FOLLOWED BY ANOTHER QUICK MOVING SYSTEM APPROACHING THE REGION TUESDAY. THE MODELS AGREE SHOWING A MOISTURE INCREASE TUESDAY ASSOCIATED WITH A COLD FRONT. THE GFS AND ECMWF MOS SUPPORT BELOW NORMAL TEMPERATURES SATURDAY THROUGH MONDAY...AND NEAR NORMAL DURING THE REST OF THE MEDIUM-RANGE PERIOD. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... A WEAK BUT COMPLEX LOW PRESSURE SYSTEM WILL SLOWLY LIFT NORTHWARD ACROSS THE AREA EARLY THIS AFTERNOON. EXPECT IFR OR LIFR CEILINGS TO LIFT EARLY THIS AFTERNOON WITH PATCHY LIGHT SHOWERS OR DRIZZLE AT TIMES...MAINLY OVER THE SC MIDLANDS. AS THE WARM FRONT LIFTS NORTH OF THE AREA CONDITIONS SHOULD IMPROVE AND AS LOW CLOUDS LIFT AFTER 18Z-21Z. DEEP MIXING WITHIN AN INCREASING PRESSURE GRADIENT/COLD FRONTAL PASSAGE FROM THE WEST...WILL RESULT IN STRONG SOUTHWEST TO WESTERLY WINDS WITH GUSTS TO 25 KNOTS. WINDS WILL SUBSIDE BY EARLY THIS EVENING...WITH SKIES BECOMING CLEAR DURING THE OVERNIGHT HOURS. HIGH PRESSURE WILL BUILD OVER THE AREA THURSDAY. EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION EXPECTED. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR SCZ015-016- 018-020>022-025>031-035>038-041. GA...LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR GAZ040- 063>065-077. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
150 PM EST WED FEB 13 2013 .Forecast Update... Issued at 150 PM EST Wed Feb 13 2013 Snow continues to wind down across northwest sections of the forecast area. Satellite data does show clouds breaking up to our west so some peeks of sunshine will be possible. Temperatures have already risen a few degrees since the snowfall ended and snow has largely melted away already in the Metro area. With the threat of snow greatly diminished, have gone ahead and cancelled the western section of the winter weather advisory. Further east, band of light to moderate snow continues to work eastward and will be impacting the Lexington metro region. This will put down a quick accumulation mainly on grassy surfaces before diminishing to flurries later this afternoon. && .Short Term (Now through Thursday)... Issued at 325 AM EST Wed Feb 13 2013 ...Light Slushy Snow Accumulations Possible Today... As of 745Z, an upper trough was over MO with sfc low pressure over the Gulf States. Precipitation associated with this system stretched from western KY to eastern OK as of 745Z with rain observed over most areas ESE of the upper trough and snow or a rain/snow mix observed over portions of OK/MO/AR in the upper level trough. The 6Z NAM12 and last few RAP runs seem to have the best handle on the area of precipitation and general schematic of ptype. Overall timing of the best precip and forcing seems to be a little earlier than previously thought. Looks like the best dynamics and precip should fall over our region between 12-18Z. Also, the latest runs of the NAM and RAP have moved the best band of moderate to heavy precip...probably a heavy wet snow as observed out in MO...to the north. According to these models, the best snow band in which we could see 1-2 inches of wet, slushy snow would be in a corridor along the Ohio River to along the Western KY and Bluegrass Parkways. Other areas over southern Indiana and south central KY may see a brief mix of rain/snow...enough to create a dusting to a half inch before quickly melting off. There is still some uncertainty in where the band of moderate to heavy snow will set up so stay tuned to morning forecast updates. Also, because of the uncertainty, will continue with the SPS product instead of going with an advisory although one may be needed later this morning. So for today expect light rain to overspread the area before sunrise with possibly some snow grains mixing in over southern Indiana and northern KY at precip onset due to a deeper cold layer. After sunrise we`ll start to see colder air filter in with the upper trough causing precip to change over to a rain/snow mix and then probably all snow for a time over southern Indiana and central KY. The morning hours after sunrise through early afternoon will be the best time for a period of moderate to heavy wet snow resulting in slushy snow accumulations as high as 1-2 inches over north central KY. This period of wintry precip may cause some travel issues. We`ll continue to see a early afternoon before precip exits to our east by late afternoon/early evening. Once snow comes to an end over any location, quick melting can be expected as sfc temps are expected to be above freezing today. In fact, most locations will still top out in the upper 30s to lower 40s this afternoon despite any morning/early afternoon snow. For tonight and Thurs, expect dry conditions with partly cloudy skies. Low temps will be in the upper 20s to lower 30s tonight. An upper level trough and cold front will approach the region by Thurs evening. Ahead of the trough, though, Thurs will be quite warm with a strong southerly flow in place. High temps Thurs should be in the low to mid 50s. .Long Term (Thursday Night - Tuesday)... Issued at 320 AM EST Wed Feb 13 2013 ...A few shots for snow showers followed by a warm up and another strong storm system early next week... A lead shortwave will move across the Great Lakes on Thursday night, with the associated surface system dragging a moisture starved cold frontal boundary through the region. A secondary shortwave will quickly move across the Ohio Valley on Friday as overall trough envelopes the eastern CONUS. Friday looks to be the best setup for some snow showers across the area as enough deep moisture combines with steep low and mid level lapse rates, and an upslope surface component. Soundings for this time period do show some convective instability with saturation well into the -10 -20 C range across northern portions of the CWA. Surface temperatures may squeak into the mid and upper 30s on Friday, however thermal profile will be easily cold enough for all snow showers below 40 degrees, some of which could produce bursts of heavy snow and gusty winds. At this point, best location for snow looks to be across southern Indiana and north central Kentucky. As was mentioned in the previous forecast, these snow showers have the potential to cause an impact across the region with very light but quick accumulations. This setup will have to be monitored. We should see a lull in the activity on Friday night with subsidence behind the quickly departing shortwave. Temperatures will be much cooler with lows dropping into the mid 20s. By Saturday, confidence is low as to exact placement of trough axis. Models are still having trouble with the timing/placement of individual waves and the overall progression of the east CONUS trough amplification. Have continued the trend of a drier Saturday as a GFS/GEM/GFS ensemble mean consensus agree on an eastern solution with subsidence aloft already in place across the Ohio Valley on Saturday. The less consistent ECMWF still holds the axis to the west. Will only mention a slight chance of a snow shower east of I-65 to account for this. May be able to go completely dry for Saturday with the next set of model runs. Temperatures will be cooler than Friday with highs only topping out in the low and mid 30s. Saturday night/Sunday morning will be the coldest of the period as lows drop to around 20. Radiational cooling conditions will not be optimal as surface winds stay up a bit and some upper level clouds look to stream overhead. Therefore, cannot drop low too near dew points that will be in the lower teens. May be able to decouple a few of the coolest spots into the upper teens but the upper level cloud cover should mostly mitigate this. Saturday night through most of Monday should be dry as surface high pressure holds over the area and weak upper level ridging holds. Sunday will begin the warming trend with highs warming into the mid 30s to low 40s. Highs on Monday will be much milder with a return of southerly flow. The mercury should rebound to the low 50s in most spots. By Monday afternoon we will begin to focus on the next storm system that looks to impact the area through Tuesday. This system will develop as a lee surface low intensifies ahead of a digging trough over the central Plains. At this point the low looks to move from the southern Plains, northeastward either into the Ohio Valley or just north to the lower Great Lakes through Tuesday morning. This warmer solution would bring overrunning rain showers to the area late Monday afternoon, with more widespread rain moving into the area Monday night and early Tuesday. Temperatures will likely crash quickly behind the system on Tuesday afternoon as sharp trough moves through and may eventually have to mention rain changing to snow. Will stick with all rain for now as it is too early to mention these details, especially with the low track in question. Will also leave any thunder mention out of the forecast with the bulk of the precipitation as any moisture return/instability would be limited by short duration of southerly flow. This system will have to be watched however, as a more northerly solution or deeper sfc low would change the instability picture. Also, chose to disregard the more southern solution offered by the operational ECMWF. This seems to be the outlier, with a general consensus between the GFS/GEM/GFS ensemble mean/ECMWF ensemble mean of a northern solution. && .Aviation (18Z TAF Issuance)... Issued at 1235 PM EST Wed Feb 13 2013 Mid-level vorticity maximum continues to push eastward across the forecast area this afternoon. Weakening band of heavy to moderate snow will continue to push eastward. It should be east of KSDF by the beginning of the TAF period, but several bands still remain to the west which should push through over the next hour. MVFR conditions look likely, but can not rule out a tempo drop to IFR as these bands push through. VFR conditions are expected to return to KSDF by 13/21Z and continue through the remainder of the TAF period. Winds will be out of the northwest at 5-8 knots and then gradually shift the west and then southwest later this afternoon and tonight. Over at KLEX, band of snow between KSDF and KLEX will push eastward this afternoon and bring snow to the KLEX terminal. Current thinking is the band will go through KLEX between 13/18-20Z or so and conditions will likely drop to IFR for a short period of time before rising back up to MVFR by 13/21Z. VFR conditions should return to KLEX by 14/00Z. Surface winds will be out of northwest at 8-10 kts with winds shifting back to the west/southwest tonight. Down at KBWG, some light rainfall mixed with a little snow will be possible over the next few hours. In general, MVFR cigs and VFR visibilities are expected, but VFR conditions should return by 13/21Z. VFR conditions are expected overnight with winds remaining out of the southwest at 3-6 knots. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR KYZ035>037-039>043-046>049-054>057-067. $$ Update...........MJ Short Term.......AMS Long Term........BJS Aviation.........MJ
AREA FORECAST DISCUSSION
NWS JACKSON KY
113 PM EST WED FEB 13 2013 .UPDATE... ISSUED AT 931 AM EST WED FEB 13 2013 LIGHT...INTERMITTENT RAIN WITH TEMPS AROUND 40 COVERING MOST OF THE CWFA. LOWER TEMPS AND LIGHT SNOW TO OUR WEST. UPDATED GRIDS TO INDICATE LATE MORNING HIGH TEMPS AND THEN FALLING TEMPS THIS AFTERNOON. RAIN SHOULD CHANGE TO SNOW AND THERE MAY BE A FEW BANDS OF SNOW TO ACCUMULATE BUT THE GROUND AND ESPECIALLY THE ROADS ARE TOO WARM TO SUPPORT OTHER THAN MOMENTARY ACCUMULATIONS. BY THE TIME THE COLD AIR ARRIVES AND THE RAIN CHANGES TO ALL SNOW...MOST OF THE MOISTURE WILL BE EAST OF THE AREA AND JUST A FEW FLURRIES WILL REMAIN FOR ALL BUT THE HIGHER ELEVATIONS NEAR THE VA/W VA BORDER. UPDATED GRIDS AND ZONES WITH LATEST INFORMATION. UPDATE ISSUED AT 658 AM EST WED FEB 13 2013 CURRENT CONDITIONS ACROSS EASTERN KENTUCKY HAVE PRECIP MOVING INTO THE AREA WITH RAIN REACHING THE GROUND IN THE SOUTH. HAVE UPDATED TO FINE TUNE POPS AND ANY COOLING EFFECTS TO TEMPS FROM THE RAINFALL. UPSTREAM...IT SEEMS THE BAND SETTING UP WILL STAY JUST NORTH SO WILL KEEP CURRENT SNOWFALL FORECAST IN PLACE. ONLY CONCERN RIGHT NOW IS THE COOLING EFFECTS AND SURFACE TEMPS OVER THE SOUTH AS SOME REPORTS OF MODERATE RAIN POSSIBLY REALLY COOLING SURFACE TEMPS. WILL BANK ON SURFACE TEMPS STAYING WARM ENOUGH THROUGH THE EARLY AFTERNOON BEFORE THE COLD AIR FINALLY CHANGES THE RAIN OVER THIS AFTERNOON. ALSO...MODEL SOUNDINGS CONTINUE TO SHOW DRY AIR AIR AT THE 10 DEGREE CELSIUS TEMPS AND HIGHER SO WILL KEEP THE INCH OR SNOW FORECAST NORTH OF THE MOUNTAIN PARKWAY AND IN THE HIGHEST ELEVATIONS SO NO NEW ZFP WAS NEEDED. && .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 423 AM EST WED FEB 13 2013 CURRENT 09Z ANALYSIS ACROSS THE AREA HAS WIDESPREAD CLOUD COVER OVER EASTERN KENTUCKY WITH PRECIP ALONG THE TN AND KY BORDER IN SOUTH CENTRAL KY DEVELOPING AND MOVING INTO THE AREA. CURRENT TEMPERATURES ACROSS THE SOUTHERN PORTION OF THE AREA ARE IN THE LOW 40S TO UPPER 30S. HOWEVER SURFACE TEMPS ALONG AND NORTH OF THE MOUNTAIN PARKWAY ARE COLD ENOUGH TO SUSTAIN SOME SNOWFALL AS THE PRECIP WILL CREEP INTO THE NORTHERN PORTION OF THE CWA BY 12Z. MET SAT DATA CURRENTLY SHOWS THE DEVELOPING SURFACE LOW OVER THE LOWER TN VALLEY AND SHIFTING OFF TO THE NORTHEAST. THE UPPER LOW IS LOCATED OVER SOUTHERN IL MOVING TO THE EAST NORTHEAST. CURRENT SHORT TERM MODELS INDICATE A BAND OF HEAVY PRECIP SETTING UP. THE CHALLENGE HERE IS THE LOCATION OF THE DEVELOPMENT. BOTH THE NAM AND GFS HAVE INDICATED A BAND OF HEAVIER PRECIP JUST SOUTH OF THE OH RIVER AND ALSO ANOTHER BAND GOING THROUGH CENTRAL EASTERN KY. THE HI RES HRRR ALSO SHOWS THIS BUT WITH THE SOUTHERN BAND NOT AS INTENSE. BASED ON CURRENT WV SHOWING MID LEVEL MOISTURE AND ADVECTING TOWARD THE UPPER OH VALLEY...HAVE GONE WITH THE BLUEGRASS AND LOCATIONS NORTH OF THE MOUNTAIN PARKWAY TO RECEIVE UP TO AN INCH OF SNOWFALL. CURRENT THOUGH IS WITH THE SOUTHEAST KY STILL QUITE WARMER THAN THE NORTH LOCATIONS...THE BAND INDICATED THROUGH THE CENTRAL PORTION OF EAST KY...WILL MAINLY BE A RAIN PRODUCER WITH THE BEST CHANCE FOR ACCUMULATING SNOW ION THE HIGHER TERRAIN ALONG THE VA BORDER. AS WELL...NAM MODEL SOUNDINGS STILL SHOW A POOR DENDRITE GROWTH ZONE THROUGH MUCH OF THE EVENT...LOCATED FROM THE JKL POINT AND SOUTH. BASED ON ALL THESE FACTORS...HAVE KEPT THE SPS GOING WITH THE INCH POSSIBLE NORTH OF THE MOUNTAIN PARKWAY AND IN THE HIGHER TERRAIN ALONG THE VA BORDER. IF THE BAND IN THE NORTH DOES SLIDE SOUTH A BIT...THE BLUE GRASS COUNTIES WILL QUICKLY REACH ADVISORY CRITERIA. FOR THE REST OF THE SHORT TERM...A PROGRESSIVE PATTERN REMAINS...SUCH THAT...LOCATIONS THAT FINALLY BECOME COLD ENOUGH TO SUPPORT SNOW THIS EVENING AND TONIGHT...MUCH OF THE MOISTURE WILL BE OUT OF THE AREA WITH A FEW FLURRIES POSSIBLE. THE PATTERN WILL ALLOW A BRIEF STAY FOR THIS COLDER AIR MASS AS THURSDAY HIGH TEMPS WILL QUICKLY WARM INTO THE UPPER 40S...MELTING ANY SNOW THAT FALLS TODAY AND TONIGHT. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 341 AM EST WED FEB 13 2013 THE MODEL START OFF IN FAIRLY GOOD AGREEMENT WITH AN UPPER TROUGH EXTENDING ACROSS THE MIDWEST. THIS UPPER TROUGH WILL PUSH A WEAK FRONT ACROSS THE AREA ON FRIDAY BRINGING INITIALLY A MIX OF RAIN AND SNOW IN THE MORNING AND THEN TURNING TO ALL RAIN AS IT WARMS UP A LITTLE IN THE AFTERNOON AND THEN A MIX OF RAIN AND SNOW AGAIN IN THE EVENING WHEN THINGS COOL OFF AGAIN. AT WORST...A DUSTING OF SNOW IS EXPECTED WITH THIS SYSTEM. SOME FLURRIES OR VERY LIGHT SNOW IS POSSIBLE ON SATURDAY AS THE UPPER TROUGH MOVES THROUGH THE AREA. THIS IS ALSO WHERE THE MODELS REALLY BEGIN TO DIVERGE WITH THE ECMWF ABOUT 12 HOURS SLOWER WITH THE UPPER TROUGH PASSAGE. ALSO THE ECMWF HAS A MUCH SHARPER AND DEEPER UPPER TROUGH THAN THE GFS. THE MODELS THEN GET INTO BETTER AGREEMENT WITH A MORE ZONAL PATTERN DEVELOPING ACROSS THE US. THE NEXT SYSTEM TO MOVE ACROSS EASTERN KENTUCKY WILL BE ON TUESDAY. HERE THE ECMWF IS THE FASTER OF THE TWO SYSTEMS. DECIDED TO GO WITH THE FASTER ECMWF FOR THE TUESDAY SYSTEM. THE PATTERN THUS REMAINS ACTIVE...HOWEVER NO MAJOR SYSTEMS WITH BIG IMPACT ARE EXPECTED. FOR THE TEMPERATES...GENERALLY NUDGED THE MODEL BLEND TOWARD THE NEW AND GENERALLY WARMER ECMWF RAW DATA FOR THE TEMPERATURE FORECAST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 108 PM EST WED FEB 13 2013 CEILINGS HAVE DROPPED TO IFR LEVELS. PRECIP HAS FALLEN THROUGH THE MORNING ACROSS THE AREA IN THE FORM OF -RA. EXPECT THIS TO MIX WITH AND THEN CHANGE TO -SN LATER THIS AFTERNOON. ACCUMULATIONS WILL BE GENERALLY LIGHT EXCEPT IN NORTHERN KY WHERE A QUICK INCH COULD FALL. PRECIP SHOULD END ACROSS EASTERN KENTUCKY BETWEEN 1-3Z WITH CIGS/VSBY LIFTING TO VFR. WHERE THERE IS PRECIPITATION...THE -RA AND THEN THE MIX OF TYPES COULD CAUSE SOME ICE ACCUMULATION WHEN AIRBORNE. && .JKL WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR KYZ044- 050>052. && $$ UPDATE...DUSTY SHORT TERM...SHALLENBERGER LONG TERM...JJ AVIATION...DUSTY
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1203 PM EST WED FEB 13 2013 .Forecast Update... Issued at 1202 PM EST Wed Feb 13 2013 Heavy snow band continues to steadily move eastward. The band is now located just east and southeast of the Ohio River and currently pushing through Louisville metro. This band has shown some weakening in the last hour or so, but with the band passing over the radar site, we might be seeing a little attenuation in the current radar moments. This band will continue to head east through the afternoon hours. Thus, have gone ahead and expanded the advisory to the east to include all of the Bluegrass region of central Kentucky. Overall, not expecting that many problems with accumulation on the road surfaces as they have been pretty warm. However, a short period of slushy roads will be possible...especially on bridges and overpasses. Further south, there is a little bit more warm air moving in which is keeping the precipitation more in a mixed mode. It appears, based on observations and reports that the pure snow line is along the southern edge of the advisory area. Some colder air will move in this afternoon which may result in a little more snow, but accumulations will be very limited with a dusting or less. There are some secondary bands that have formed to the west and northwest across southern Indiana. In general, this snow is much lighter than the main band, but light snow looks to continue through the afternoon in southern Indiana with little additional accumulation, and that would be limited to grassy surfaces. && .Short Term (Now through Thursday)... Issued at 325 AM EST Wed Feb 13 2013 ...Light Slushy Snow Accumulations Possible Today... As of 745Z, an upper trough was over MO with sfc low pressure over the Gulf States. Precipitation associated with this system stretched from western KY to eastern OK as of 745Z with rain observed over most areas ESE of the upper trough and snow or a rain/snow mix observed over portions of OK/MO/AR in the upper level trough. The 6Z NAM12 and last few RAP runs seem to have the best handle on the area of precipitation and general schematic of ptype. Overall timing of the best precip and forcing seems to be a little earlier than previously thought. Looks like the best dynamics and precip should fall over our region between 12-18Z. Also, the latest runs of the NAM and RAP have moved the best band of moderate to heavy precip...probably a heavy wet snow as observed out in MO...to the north. According to these models, the best snow band in which we could see 1-2 inches of wet, slushy snow would be in a corridor along the Ohio River to along the Western KY and Bluegrass Parkways. Other areas over southern Indiana and south central KY may see a brief mix of rain/snow...enough to create a dusting to a half inch before quickly melting off. There is still some uncertainty in where the band of moderate to heavy snow will set up so stay tuned to morning forecast updates. Also, because of the uncertainty, will continue with the SPS product instead of going with an advisory although one may be needed later this morning. So for today expect light rain to overspread the area before sunrise with possibly some snow grains mixing in over southern Indiana and northern KY at precip onset due to a deeper cold layer. After sunrise we`ll start to see colder air filter in with the upper trough causing precip to change over to a rain/snow mix and then probably all snow for a time over southern Indiana and central KY. The morning hours after sunrise through early afternoon will be the best time for a period of moderate to heavy wet snow resulting in slushy snow accumulations as high as 1-2 inches over north central KY. This period of wintry precip may cause some travel issues. We`ll continue to see a early afternoon before precip exits to our east by late afternoon/early evening. Once snow comes to an end over any location, quick melting can be expected as sfc temps are expected to be above freezing today. In fact, most locations will still top out in the upper 30s to lower 40s this afternoon despite any morning/early afternoon snow. For tonight and Thurs, expect dry conditions with partly cloudy skies. Low temps will be in the upper 20s to lower 30s tonight. An upper level trough and cold front will approach the region by Thurs evening. Ahead of the trough, though, Thurs will be quite warm with a strong southerly flow in place. High temps Thurs should be in the low to mid 50s. .Long Term (Thursday Night - Tuesday)... Issued at 320 AM EST Wed Feb 13 2013 ...A few shots for snow showers followed by a warm up and another strong storm system early next week... A lead shortwave will move across the Great Lakes on Thursday night, with the associated surface system dragging a moisture starved cold frontal boundary through the region. A secondary shortwave will quickly move across the Ohio Valley on Friday as overall trough envelopes the eastern CONUS. Friday looks to be the best setup for some snow showers across the area as enough deep moisture combines with steep low and mid level lapse rates, and an upslope surface component. Soundings for this time period do show some convective instability with saturation well into the -10 -20 C range across northern portions of the CWA. Surface temperatures may squeak into the mid and upper 30s on Friday, however thermal profile will be easily cold enough for all snow showers below 40 degrees, some of which could produce bursts of heavy snow and gusty winds. At this point, best location for snow looks to be across southern Indiana and north central Kentucky. As was mentioned in the previous forecast, these snow showers have the potential to cause an impact across the region with very light but quick accumulations. This setup will have to be monitored. We should see a lull in the activity on Friday night with subsidence behind the quickly departing shortwave. Temperatures will be much cooler with lows dropping into the mid 20s. By Saturday, confidence is low as to exact placement of trough axis. Models are still having trouble with the timing/placement of individual waves and the overall progression of the east CONUS trough amplification. Have continued the trend of a drier Saturday as a GFS/GEM/GFS ensemble mean consensus agree on an eastern solution with subsidence aloft already in place across the Ohio Valley on Saturday. The less consistent ECMWF still holds the axis to the west. Will only mention a slight chance of a snow shower east of I-65 to account for this. May be able to go completely dry for Saturday with the next set of model runs. Temperatures will be cooler than Friday with highs only topping out in the low and mid 30s. Saturday night/Sunday morning will be the coldest of the period as lows drop to around 20. Radiational cooling conditions will not be optimal as surface winds stay up a bit and some upper level clouds look to stream overhead. Therefore, cannot drop low too near dew points that will be in the lower teens. May be able to decouple a few of the coolest spots into the upper teens but the upper level cloud cover should mostly mitigate this. Saturday night through most of Monday should be dry as surface high pressure holds over the area and weak upper level ridging holds. Sunday will begin the warming trend with highs warming into the mid 30s to low 40s. Highs on Monday will be much milder with a return of southerly flow. The mercury should rebound to the low 50s in most spots. By Monday afternoon we will begin to focus on the next storm system that looks to impact the area through Tuesday. This system will develop as a lee surface low intensifies ahead of a digging trough over the central Plains. At this point the low looks to move from the southern Plains, northeastward either into the Ohio Valley or just north to the lower Great Lakes through Tuesday morning. This warmer solution would bring overrunning rain showers to the area late Monday afternoon, with more widespread rain moving into the area Monday night and early Tuesday. Temperatures will likely crash quickly behind the system on Tuesday afternoon as sharp trough moves through and may eventually have to mention rain changing to snow. Will stick with all rain for now as it is too early to mention these details, especially with the low track in question. Will also leave any thunder mention out of the forecast with the bulk of the precipitation as any moisture return/instability would be limited by short duration of southerly flow. This system will have to be watched however, as a more northerly solution or deeper sfc low would change the instability picture. Also, chose to disregard the more southern solution offered by the operational ECMWF. This seems to be the outlier, with a general consensus between the GFS/GEM/GFS ensemble mean/ECMWF ensemble mean of a northern solution. && .Aviation (12Z TAF Issuance)... Issued at 605 AM EST Wed Feb 13 2013 An upper level trough will pass through the area today with a sfc low pressure passing to our south. Precipitation associated with this weather system has already begun to spread northward into central KY this morning. At the beginning of TAF time, it should be raining near all TAF sites with SDF/LEX rains being more intermittent showers until deeper moisture overtakes the low level dry layer. After sunrise, good forcing will enter the region causing steady moderate banded precip over the region. It`s hard to say whether a moderate band will affect the TAF sites, but at least feel confident enough to include lower MVFR conditions this morning through early afternoon as the heavier precip moves through the region. Some IFR cigs may be possible in some of the heavier bands of precip especially near BWG but will not include in the TAF at this time as confidence is low. Rain is expected to be the predominant precip type for BWG, however, SDF/LEX could see a RASN mix in a moderate band. A RASN mix isn`t out of the realm of possibilities for BWG either, but seems most likely at SDF/LEX at this time. Will need to adjust as the precip bands set up this morning and move closer to our area. By mid to late afternoon, precip should move east of the TAF sites with conditions returning to high end MVFR and then VFR by this evening. Winds will be predominantly NNE as the weather system moves through the area this morning through mid afternoon. Winds will strengthen throughout the day likely exceeding 7kt at times. Winds will shift to the WNW behind this system by this evening. NAM model soundings indicate a layer of low level moisture for tomorrow morning which could indicate a light fog or low cigs. Will not place flight restrictions at the end of the TAFs for now, but it will be something to investigate further. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY UNTIL 4 PM EST /3 PM CST/ THIS AFTERNOON FOR INZ076>079-083-084-089>092. KY...WINTER WEATHER ADVISORY UNTIL 4 PM EST /3 PM CST/ THIS AFTERNOON FOR KYZ023>034-038-045-053. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR KYZ035>037-039>043-046>049-054>057-067. $$ Update...........MJ Short Term.......AMS Long Term........BJS Aviation.........AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1103 AM EST WED FEB 13 2013 .Mesoscale Forecast Update... Issued at 1103 AM EST Wed Feb 13 2013 Strong frontogenetical heavy snow band is now moving into the Louisville Metro area. Conditions across the metro will deteriorate quickly over the next 15-20 minutes as the snow picks up. Visibilities will drop to less than a mile and the snow will quickly accumulate. Temperatures have continued to drop to near their dewpoints in the snow band, so we expect temperatures to drop right to freezing in the next half hour as the band pushes in. The heavy snow will last about 60-90 minutes and a good 1-2" of accumulation is likely. Webcams to our north and northwest show the accumulating snows well. Via social media, we`re seeing reports of 2-3" and we had a co-op observer in Crawford County IN report 2 inches in the last hour. This snow band will also affect areas to the southwest of Louisville including areas from Harrison County Indiana southwest through Meade/Breckinridge/Hardin/Ohio/Grayson counties over the next 60-90 minutes. && .Short Term (Now through Thursday)... Issued at 325 AM EST Wed Feb 13 2013 ...Light Slushy Snow Accumulations Possible Today... As of 745Z, an upper trough was over MO with sfc low pressure over the Gulf States. Precipitation associated with this system stretched from western KY to eastern OK as of 745Z with rain observed over most areas ESE of the upper trough and snow or a rain/snow mix observed over portions of OK/MO/AR in the upper level trough. The 6Z NAM12 and last few RAP runs seem to have the best handle on the area of precipitation and general schematic of ptype. Overall timing of the best precip and forcing seems to be a little earlier than previously thought. Looks like the best dynamics and precip should fall over our region between 12-18Z. Also, the latest runs of the NAM and RAP have moved the best band of moderate to heavy precip...probably a heavy wet snow as observed out in MO...to the north. According to these models, the best snow band in which we could see 1-2 inches of wet, slushy snow would be in a corridor along the Ohio River to along the Western KY and Bluegrass Parkways. Other areas over southern Indiana and south central KY may see a brief mix of rain/snow...enough to create a dusting to a half inch before quickly melting off. There is still some uncertainty in where the band of moderate to heavy snow will set up so stay tuned to morning forecast updates. Also, because of the uncertainty, will continue with the SPS product instead of going with an advisory although one may be needed later this morning. So for today expect light rain to overspread the area before sunrise with possibly some snow grains mixing in over southern Indiana and northern KY at precip onset due to a deeper cold layer. After sunrise we`ll start to see colder air filter in with the upper trough causing precip to change over to a rain/snow mix and then probably all snow for a time over southern Indiana and central KY. The morning hours after sunrise through early afternoon will be the best time for a period of moderate to heavy wet snow resulting in slushy snow accumulations as high as 1-2 inches over north central KY. This period of wintry precip may cause some travel issues. We`ll continue to see a early afternoon before precip exits to our east by late afternoon/early evening. Once snow comes to an end over any location, quick melting can be expected as sfc temps are expected to be above freezing today. In fact, most locations will still top out in the upper 30s to lower 40s this afternoon despite any morning/early afternoon snow. For tonight and Thurs, expect dry conditions with partly cloudy skies. Low temps will be in the upper 20s to lower 30s tonight. An upper level trough and cold front will approach the region by Thurs evening. Ahead of the trough, though, Thurs will be quite warm with a strong southerly flow in place. High temps Thurs should be in the low to mid 50s. .Long Term (Thursday Night - Tuesday)... Issued at 320 AM EST Wed Feb 13 2013 ...A few shots for snow showers followed by a warm up and another strong storm system early next week... A lead shortwave will move across the Great Lakes on Thursday night, with the associated surface system dragging a moisture starved cold frontal boundary through the region. A secondary shortwave will quickly move across the Ohio Valley on Friday as overall trough envelopes the eastern CONUS. Friday looks to be the best setup for some snow showers across the area as enough deep moisture combines with steep low and mid level lapse rates, and an upslope surface component. Soundings for this time period do show some convective instability with saturation well into the -10 -20 C range across northern portions of the CWA. Surface temperatures may squeak into the mid and upper 30s on Friday, however thermal profile will be easily cold enough for all snow showers below 40 degrees, some of which could produce bursts of heavy snow and gusty winds. At this point, best location for snow looks to be across southern Indiana and north central Kentucky. As was mentioned in the previous forecast, these snow showers have the potential to cause an impact across the region with very light but quick accumulations. This setup will have to be monitored. We should see a lull in the activity on Friday night with subsidence behind the quickly departing shortwave. Temperatures will be much cooler with lows dropping into the mid 20s. By Saturday, confidence is low as to exact placement of trough axis. Models are still having trouble with the timing/placement of individual waves and the overall progression of the east CONUS trough amplification. Have continued the trend of a drier Saturday as a GFS/GEM/GFS ensemble mean consensus agree on an eastern solution with subsidence aloft already in place across the Ohio Valley on Saturday. The less consistent ECMWF still holds the axis to the west. Will only mention a slight chance of a snow shower east of I-65 to account for this. May be able to go completely dry for Saturday with the next set of model runs. Temperatures will be cooler than Friday with highs only topping out in the low and mid 30s. Saturday night/Sunday morning will be the coldest of the period as lows drop to around 20. Radiational cooling conditions will not be optimal as surface winds stay up a bit and some upper level clouds look to stream overhead. Therefore, cannot drop low too near dew points that will be in the lower teens. May be able to decouple a few of the coolest spots into the upper teens but the upper level cloud cover should mostly mitigate this. Saturday night through most of Monday should be dry as surface high pressure holds over the area and weak upper level ridging holds. Sunday will begin the warming trend with highs warming into the mid 30s to low 40s. Highs on Monday will be much milder with a return of southerly flow. The mercury should rebound to the low 50s in most spots. By Monday afternoon we will begin to focus on the next storm system that looks to impact the area through Tuesday. This system will develop as a lee surface low intensifies ahead of a digging trough over the central Plains. At this point the low looks to move from the southern Plains, northeastward either into the Ohio Valley or just north to the lower Great Lakes through Tuesday morning. This warmer solution would bring overrunning rain showers to the area late Monday afternoon, with more widespread rain moving into the area Monday night and early Tuesday. Temperatures will likely crash quickly behind the system on Tuesday afternoon as sharp trough moves through and may eventually have to mention rain changing to snow. Will stick with all rain for now as it is too early to mention these details, especially with the low track in question. Will also leave any thunder mention out of the forecast with the bulk of the precipitation as any moisture return/instability would be limited by short duration of southerly flow. This system will have to be watched however, as a more northerly solution or deeper sfc low would change the instability picture. Also, chose to disregard the more southern solution offered by the operational ECMWF. This seems to be the outlier, with a general consensus between the GFS/GEM/GFS ensemble mean/ECMWF ensemble mean of a northern solution. && .Aviation (12Z TAF Issuance)... Issued at 605 AM EST Wed Feb 13 2013 An upper level trough will pass through the area today with a sfc low pressure passing to our south. Precipitation associated with this weather system has already begun to spread northward into central KY this morning. At the beginning of TAF time, it should be raining near all TAF sites with SDF/LEX rains being more intermittent showers until deeper moisture overtakes the low level dry layer. After sunrise, good forcing will enter the region causing steady moderate banded precip over the region. It`s hard to say whether a moderate band will affect the TAF sites, but at least feel confident enough to include lower MVFR conditions this morning through early afternoon as the heavier precip moves through the region. Some IFR cigs may be possible in some of the heavier bands of precip especially near BWG but will not include in the TAF at this time as confidence is low. Rain is expected to be the predominant precip type for BWG, however, SDF/LEX could see a RASN mix in a moderate band. A RASN mix isn`t out of the realm of possibilities for BWG either, but seems most likely at SDF/LEX at this time. Will need to adjust as the precip bands set up this morning and move closer to our area. By mid to late afternoon, precip should move east of the TAF sites with conditions returning to high end MVFR and then VFR by this evening. Winds will be predominantly NNE as the weather system moves through the area this morning through mid afternoon. Winds will strengthen throughout the day likely exceeding 7kt at times. Winds will shift to the WNW behind this system by this evening. NAM model soundings indicate a layer of low level moisture for tomorrow morning which could indicate a light fog or low cigs. Will not place flight restrictions at the end of the TAFs for now, but it will be something to investigate further. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY UNTIL 4 PM EST /3 PM CST/ THIS AFTERNOON FOR INZ076>079-083-084-089>092. KY...WINTER WEATHER ADVISORY UNTIL 4 PM EST /3 PM CST/ THIS AFTERNOON FOR KYZ023>034-038-045-053. $$ Mesoscale........MJ Short Term.......AMS Long Term........BJS Aviation.........AMS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1123 AM CST WED FEB 13 2013 .AVIATION...18Z TAF. WEST TO NORTHWEST WINDS WILL INCREASE THIS AFTERNOON AND CONTINUE THROUGH THE NIGHT. DURING THE MORNING ON THURSDAY THE WINDS WILL INCREASE FURTHER. VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. && .PREV DISCUSSION... /ISSUED 453 AM CST WED FEB 13 2013/ SHORT TERM...THROUGH FRIDAY NIGHT. THE MAIN STORIES THROUGH THE NEXT 72 HOURS INVOLVE A DOWNWARD TREND IN TEMPS AFTER A VERY MILD ONE TODAY...STRONG NORTHWEST WINDS ON THURSDAY THAT MAY VERY WELL REQUIRE A WIND ADVISORY ISSUANCE FOR AT LEAST PARTS OF THE AREA...AND THE POSSIBILITY OF A FEW ROUNDS OF PASSING FLURRIES DURING THE THURSDAY AFTERNOON THROUGH FRIDAY EVENING TIME FRAME BUT WITH LITTLE...IF ANY RISK OF ACCUMULATING SNOW. IN ADDITION...THE COMBINATION OF WARM AIR AND/OR GUSTY WINDS WILL PROMOTE AT LEAST SOME ELEVATED...BUT LIKELY NON-CRITICAL...FIRE DANGER IN PARTS OF THE AREA OVER THE NEXT FEW DAYS. THESE FIRE WEATHER CONCERNS ARE FURTHER DISCUSSED IN THE SEPARATE SECTION BELOW. 09Z CENTRAL PLAINS OBJECTIVE SURFACE ANALYSIS REVEALED A BROAD AREA OF HIGH PRESSURE EXTENDING EASTWARD OUT OF THE ROCKIES...WITH POSSIBLY A VERY SUBTLE TROUGH AXIS EXTENDING FROM FAR SOUTHEAST NEB INTO SOUTHWEST KS. THIS REGIME WAS PROMOTING FAIRLY STEADY 5-10 MPH WESTERLY BREEZES ACROSS THE MAJORITY OF THE CWA...WHICH ALONG WITH AN INCOMING BATCH OF HIGH LEVEL CLOUDS SHOULD KEEP MOST AREAS UP INTO THE 21-25 DEGREE RANGE FOR MORNING LOW TEMPS. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA SHOWED THE CENTRAL PLAINS UNDER NORTH-NORTHWEST FLOW ALOFT...IN BETWEEN THE SOUTHERN STREAM SHORTWAVE TROUGH ALONG THE MO/AR BORDER...AND A PARADE OF LOW AMPLITUDE DISTURBANCES ASSOCIATED WITH THE NORTHERN STREAM JET IN THE SOUTHWEST CANADA/MONTANA AREA. 11-3.9 MICRON SATELLITE IMAGERY REVEALS CLEAR SKIES OVER MOST OF THE CWA BUT AT LEAST A THIN LAYER OF HIGH CLOUD WILL BE PASSING OVER MOST OF THE AREA BETWEEN NOW AND SUNRISE. TODAY WILL BE THE WELL-ANTICIPATED WARMEST DAY OF THE WEEK FOR THE ENTIRE CWA. ALOFT...NORTHWEST FLOW WILL PERSIST...WITH ONLY THE MOST SUBTLE OF MOISTURE-STARVED DISTURBANCES RIDING THROUGH THE FLOW AS THE AREA REMAINS JUST SOUTH OF A SLIGHTLY STRONGER WAVE CROSSING THE DAKOTAS THIS AFTERNOON. AS A RESULT...SKY COVER WILL BE SOMEWHAT VARIABLE TODAY...GENERALLY AVERAGING PARTLY CLOUDY BUT ALTERNATING BETWEEN PERIODS OF PLENTIFUL SUNSHINE AND PASSING BATCHES OF MID-HIGH LEVEL CLOUDS. AT THE SURFACE...THE WEST- NORTHWEST WIND REGIME WILL PERSIST...AND INCREASE IN SPEED IN RESPONSE TO DEEPENING MIXING TO AT LEAST THE 850-800MB LAYER. AS A RESULT...UPPED WIND SPEEDS A BIT FROM PREVIOUS FORECAST...AS THE LATE MORNING-LATE AFTERNOON HOURS WILL FEATURE SUSTAINED SPEEDS AT LEAST 15-20 MPH WITH SOME GUSTS 25+ MPH. THE DEEP MIXING WILL COMBINE WITH SLIGHTLY WARMER AIR MOVING IN ALOFT FROM THE WEST TO RESULT IN HIGH TEMPERATURES WELL INTO THE 50S NEARLY ALL AREAS. NUDGED UP HIGH TEMPS 2-3 DEGREES FROM PREVIOUS GRIDS IN MOST AREAS...GETTING MOST PLACES UP BETWEEN 52-55 DEGREES EXCEPT SLIGHTLY COOLER UPPER 40S MAINLY IN PARTS OF VALLEY COUNTY WHERE SOME SNOW PACK REMAINS. THESE FORECAST HIGHS ARE RIGHT IN LINE WITH 07Z RAP HOURLY TEMPS...WHICH HAVE PERFORMED QUITE WELL THE PAST TWO DAYS. TONIGHT...HAVE HIGH CONFIDENCE THAT IT WILL REMAIN PRECIP- FREE...BUT THE LEADING EDGES OF A COLD FRONT WILL START BLEEDING DOWN FROM THE NORTH...IN RESPONSE TO A PARADE OF NORTHWEST-FLOW CLIPPER WAVES ALOFT THAT WILL FOCUS ALONG AN AXIS FROM NORTH DAKOTA-IOWA. SKY COVER WILL REMAIN VARIABLE THROUGH THE NIGHT...AS STEADY WEST-NORTHWEST BREEZES REMAIN UP BETWEEN 10-20 MPH WITH SOME HIGHER GUSTS. DESPITE THE WEAK COLD AIR ADVECTION...THESE WINDS AND PASSING CLOUDS SHOULD HAVE NO PROBLEM KEEPING OVERNIGHT LOW TEMPERATURES AT LEAST SLIGHTLY WARMER THAN THOSE THIS MORNING...AND MADE LITTLE CHANGE KEEPING MOST AREAS UP BETWEEN 25-29 DEGREES...AND WOULD NOT BE SURPRISED TO SEE A BIT GREATER COVERAGE OF LOWS RIGHT AROUND 30 THAN CURRENTLY DEPICTED. THURSDAY IS UNDOUBTEDLY THE MOST ACTIVE OF THE SHORT TERM PERIODS...MAINLY DUE TO STRONG WINDS. SINCE 24 HOURS AGO...MOST MODELS/GUIDANCE HAVE CONTINUED TRENDING UPWARD A BIT WITH NORTHWESTERLY SPEEDS. FOCUSING FIRST ALOFT...AS THE DAY WEARS ON A SMALL BUT FAIRLY VIGOROUS MID LEVEL SHORTWAVE TROUGH WILL DROP SOUTHWARD OUT OF THE DAKOTAS INTO NEB/IA. MEANWHILE AT THE SURFACE...THE PRESSURE GRADIENT WILL RAMP UP IN RESPONSE TO INCREASING HIGH PRESSURE EMANATING FROM AN EXPANSIVE NORTHERN ROCKIES RIDGE. ONCE DIURNAL MIXING KICKS IN AND LOW LEVEL LAPSE RATES STEEPEN...THE 06Z NAM ADVERTISES MIXING TO DEEPEN WELL UP INTO THE 800MB TO POSSIBLY 700MB RANGE...WITH AVERAGING WIND SPEEDS THROUGH THIS MIXED LAYER EASILY SUPPORTING AT LEAST LOW-END ADVISORY SUSTAINED SPEEDS BETWEEN 30-35 MPH AND GUSTS TO AROUND 45 MPH. WILL ADD THIS STRONG WIND MENTION TO THE HAZARDOUS WEATHER OUTLOOK...BUT GIVEN IT IS STILL 3 PERIODS AWAY WILL HOLD OFF ON A WIND ADVISORY FOR NOW...AND GIVE DAY SHIFT ANOTHER LOOK TO DETERMINE WHETHER AN ADVISORY MAY BE JUSTIFIED FOR ALL 30 COUNTIES...OR MAINLY FOR THE NORTHERN 1/2 OF THE CWA WHICH LOOKS SLIGHTLY MORE FAVORABLE TO MEET 30+ MPH FOR SEVERAL HOURS VERSUS SOUTHERN ZONES. THE MAIN WINDOW FOR THE STRONGEST WINDS GENERALLY LOOKS TO TARGET THE 11 AM-6 PM TIME FRAME. AS FOR PRECIP CHANCES...HAVE NOTHING MENTIONED DURING THE MORNING...BUT HAVE RE- INTRODUCED SOME FLURRY CHANCES FOR SOME AREAS NORTH OF I-80 DURING THE AFTERNOON AS LOW LEVEL STRATUS SWEEPS IN FROM THE NORTH. NOT THINKING ANYTHING ACCUMULATING AT THIS POINT...WITH BETTER CHANCES FOR A LIGHT DUSTING FOCUSING JUST NORTH OF OUR AREA. TEMP- WISE...IF IT WASN/T FOR THE WIND IT REALLY WOULDN/T FEEL TOO BAD...AND ONLY MADE MINOR TWEAKS TO HIGHS RANGING FROM UPPER 30S FAR NORTH...LOW 40S CENTRAL AND MID 40S IN KS ZONES. TAKING A BIT BROADER LOOK AT THE THURSDAY NIGHT THROUGH FRIDAY NIGHT TIME FRAME...THE BIG PICTURE ALOFT INVOLVES THE CENTRAL PLAINS REMAINING UNDER NORTHWEST FLOW ALOFT AS A CONTINUING PARADE OF MID LEVEL SHORTWAVE TROUGHS ROTATING SOUTH-SOUTHEAST OUT OF CANADA WILL CARVE OUT AN EXPANSIVE LONGWAVE TROUGH THAT WILL DOMINATE THE EASTERN TWO-THIRDS OF THE NATION. ON THURSDAY NIGHT...THE INITIAL SHORTWAVE TROUGH WILL PASS JUST SOUTHEAST OF OUR AREA...WHILE UPSTREAM THE NEXT MAIN ONE ENTERS THE DAKOTAS. WIND SPEEDS WILL EASE DOWN QUITE A BIT...ESPECIALLY POST-MIDNIGHT WHEN SPEEDS DECREASE INTO THE 5-10 MPH RANGE. ALTHOUGH SOME AREAS MAY NOT SEE A SINGLE SNOWFLAKE...OPTED TO KEEP THE GRIDS AS SIMPLE AS POSSIBLE AND BLANKET THE ENTIRE CWA WITH A SLIGHT CHANCE OF FLURRIES ALL THE WAY FROM THURSDAY NIGHT THROUGH FRIDAY EVENING AS THIS PATTERN OFTEN EVOKES SMALL-SCALE PATCHES OR BANDS OF NON- MEASURABLE SNOW UNDERNEATH THE UPPER JET EXIT REGION...ESPECIALLY IF SOME OF THE PASSING LOWER STRATUS HAS FAVORABLE DENDRITIC TEMPERATURES. ALTHOUGH SUPPOSE A SMALL PERCENTAGE OF THE CWA COULD SEE A LIGHT MEASURABLE DUSTING...ITS TOO EARLY TO DETERMINE WHERE THIS MIGHT EVEN BE...SO CANNOT JUSTIFY A MEASURABLE 20+ POP ANYWHERE AT THIS TIME FRAME. WINDS ON FRIDAY WILL REMAIN FROM THE NORTH-NORTHWEST BUT DO NOT APPEAR NEARLY AS STRONG AS THURSDAY WITH SUSTAINED SPEEDS GENERALLY TOPPING OUT AROUND 15 MPH. AS FOR TEMPS...MADE ONLY A SMALL DOWNWARD NUDGE TO THURSDAY NIGHT WITH MOST AREAS 16-20 DEGREES. FRIDAY STILL SHOULD BE THE COLDEST DAY OF THE WEEK...BUT ACTUALLY NUDGED UP VALUES A BIT IN SOME AREAS DUE TO DECENT MIXING POTENTIAL...RANGING FROM MID 30S IN MOST NEB ZONES TO NEAR 40 IN KS. BY MIDNIGHT FRIDAY NIGHT...ANY FLURRY RISK SHOULD BE OVER WITH AS THE BACK EDGE OF THE LAST IN A SERIES OF MID LEVEL SHORTWAVE TROUGHS EXITS THE AREA. LONG TERM...SATURDAY THROUGH TUESDAY. DRY CONDITIONS ARE FORECAST THROUGH THE EXTENDED PERIODS. ON SATURDAY...THE PATTERN ALOFT WILL FEATURE A TROUGH MOVING INTO THE PACIFIC NORTHWEST...RIDGING OVER THE ROCKIES AND A LONGWAVE TROUGH FROM THE HUDSON BAY SOUTH TO THE GULF COAST STATES. HEIGHTS WILL RISE ACROSS THE CENTRAL PLAINS OVER THE WEEKEND AS THE WESTERN RIDGE BUILDS ONTO PLAINS AND THE COLD AIRMASS ASSOCIATED WITH THE TROUGH TO THE EAST DEPARTS. THE RIDGE BEGINS TO BREAK DOWN SUNDAY AS AN UPSTREAM TROUGH REACHES THE NORTH CENTRAL ROCKIES. THIS NEXT TROUGH AND ASSOCIATED COLD FRONT CROSSES THE CENTRAL PLAINS SUNDAY NIGHT/MONDAY...BRINGING ANOTHER ROUND OF COLD AIR TO START THE WORKWEEK. TEMPERATURE WISE...TEMPS BEGIN TO RECOVER ON SATURDAY BEHIND THE UPPER TROUGH...THEN SUNDAY WILL BE THE WARMEST OF THE EXTENDED PERIODS WITH THE MILD AIRMASS IN PLACE AHEAD OF THE NEXT APPROACHING COLD FRONT/SYSTEM. HIGHS SUNDAY ARE LOOKING WELL ABOVE NORMAL IN THE 50S...THEN FOLLOWING COLD FROPA TEMPS RETURN CLOSER TO FEBRUARY NORMALS FOR MON/TUES. FIRE WEATHER...ALTHOUGH OUTRIGHT CRITICAL FIRE WEATHER THRESHOLDS ARE CURRENTLY NOT FORECAST DURING THE NEXT FEW DAYS...AT LEAST PARTS OF THE CWA BEAR WATCHING FOR SOME ELEVATED TO NEAR-CRITICAL COMBINATIONS OF WIND AND RELATIVE HUMIDITY. STARTING OFF TODAY...WEST-NORTHWEST SUSTAINED WIND SPEEDS WILL AVERAGE 15-20 MPH IN NEARLY ALL AREAS...WITH SPORADIC TO FREQUENT GUSTS TO 25+ MPH EXPECTED. FORTUNATELY...AFTERNOON RELATIVE HUMIDITY VALUES ACROSS MOST OF THE ARE FORECAST TO HOLD SLIGHTLY ABOVE CRITICAL LEVELS IN THE 25-30 PERCENT RANGE. HOWEVER...IT COULD BE A CLOSE CALL ESPECIALLY IN PARTS OF PHILLIPS/ROOKS/OSBORNE COUNTIES IN KANSAS...WHERE RH VALUES COULD EDGE A BIT CLOSER TO 20 PERCENT. WILL INTRODUCE AN ELEVATED FIRE DANGER MENTION INTO THE HAZARDOUS WEATHER OUTLOOK MAINLY FOR THIS AREA. TURNING TO THURSDAY...AS OUTLINED ABOVE STRONG SUSTAINED WINDS AROUND 30 MPH OR HIGHER ARE FORECAST ACROSS NEARLY THE ENTIRE CWA. FORTUNATELY...COOLER TEMPERATURES WILL KEEP AFTERNOON RH PERCENTAGES ABOVE 30 PERCENT ACROSS NEBRASKA ZONES...BUT KS ZONES COULD SEE VALUES CREEP DOWN CLOSER TO 25 PERCENT. BOTTOM LINE IS...WHILE NO MAJOR FIRE DANGER ISSUES ARE ANTICIPATED THESE NEXT FEW DAYS...SOME CAUTION MAY NEED TAKEN...AND HOURLY RELATIVE HUMIDITY TRENDS THESE NEXT FEW AFTERNOONS WILL NEED WATCHED CLOSELY TO MAKE SURE THERE ARE NO SURPRISES DROPPING BELOW 20 PERCENT. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
308 PM CST WED FEB 13 2013 .SHORT TERM... CHALLENGE FOR THE PERIOD INCLUDE SNOW TODAY AND TONIGHT WITH CLIPPER SYSTEMS AND THEN TEMPS THRU SATURDAY. MODELS IN OVERALL GENERAL AGREEMENT WITH 12Z RUNS. 12Z GFS CAME AROUND IN AGREEMENT WITH THE OVER MODELS WITH THE PLACEMENT OF TODAYS QPF. PRIMARILY USED NAM/ECMWF FOR THE PACKAGE WITH A HEAVY LEAN TO THE RAP THRU THIS EVENING. CLIPPER CURRENTLY CROSSING THE CWFA IS PRODUCING VSBYS GENERALLY 1 TO 2 MILES WITH 1/2 MI IN THE STRONGEST SN. BACK EDGE OF CLIPPER SNOW BAND JUST EXITING MINOT AREA. WILL CONTINUE WINTER WX ADVISORY AS NEXT CLIPPER IS EXPECTED TO MOVE INTO THE DVL BSN THIS EVENING AND STAY CONFINED TO THE WESTERN AND EXTREME SOUTHERN PORTIONS OF THE CWFA. TOTAL 24 HOUR SNOWFALL WITH A 14 TO 1 RATIO IN THE QUARTER TO HALF INCH QPF WILL BE IN THE 2 TO 5 INCH RANGE WITH A HIGHER TOTAL ALONG A MADDOCK TO NEW ROCKFORD TO VALLEY CITY TO LISBON LINE. THE NEXT CONCERN WOULD BE WIND POTENTIAL ON THE BACK SIDE WITH BLOWING SNOW IMPACTS. BEST COLD ADVECTION WILL LAG THE PRECIP BAND. NAM INDICATES THE STRONGEST COLD PUSH OCCUR IN THE DVL BASIN AND ACROSS THE WESTERN PORTIONS OF THE CWFA OVERNIGHT. THOUGH LOW LEVEL WINDS ARE RELATIVELY WEAK WITH A SHALLOW MIXED LAYER JUST 10 TO 15 KTS THROUGH 12Z. AS A RESULT LITTLE BLOWING SNOW IS EXPECTED. MIXED LAYER INCREASES TOMORROW WITH BETTER MIXING...TO 20KTS TO 950MB TO 20KTS AS COLD AIR PUSHES IN WITH 925 TEMPS DROPPING 10 C OR SO CAUSING DAYTIME TEMPS THURSDAY TO REMAIN FAIRLY STEADY OR EVEN FALL THROUGH THE AFTERNOON. SFC HIGH PRESSURE TO SLIDE ACROSS THE AREA FIR DAY WITH NW FLOW ALOFT. COLD START AS NEGATIVE VALUES RETURN FOR MORNING LOWS. LITTLE MIXING WILL LEAD TO SLOW TEMP RECOVERY FRIDAY. RETURN FLOW SETS UP FRI AFTERNOON WEST AND WILL HELP OFFSET DIURNAL COOLING VALLEY WEST FRIDAY NIGHT. TEMPERATURE MODERATION CONTINUES SATURDAY AS WAA INCREASES WITH HIGHS IN THE TEENS AND 20S WEST. .LONG TERM (SAT NIGHT-WED)... MODELS IN REASONABLE AGREEMENT. NEXT SHORT WAVE MOVES THROUGH SUNDAY AFTERNOON AND NIGHT. 12Z ECMWF IS COMING IN A BIT DEEPER WITH 500 MB TROUGH AND FARTHER SOUTH WITH SFC LOW WHICH WOULD BE A BIT HIGHER SNOW CHANCES OVER THE AREA THAN GFS/GEM. BEHIND THIS SHORT WAVE THERE WILL BE STRONG COLD ADVECTION WITH 850 MB TEMPS DROPPING INTO THE -18C TO -22C RANGE TUE-WED. CR ALL BLEND TEMPS LOOK REASONABLE WITH HIGHS IN THE SINGLE DIGITS TUES-WED AND LOWS IN THE 5 TO 15 BELOW RANGE. DISAGREEMENTS DO SHOW UP VERY LATE IN THE PD FOR WED NIGHT-THU IN REGARDS TO NEXT 500 MB SYSTEM DIGGING INTO THE CNTRL-SOUTHERN ROCKIES AND HOW FAR NORTH ITS IMPACT IS. GFS WETTER AND FARTHER NORTH. && .AVIATION... AREAS OF SNOW TO IMPACT DVL-FAR REGION TONIGHT...WITH MOSTLY MVFR VSBYS/CIGS...THOUGH BRIEF IFR VSBY PSBL. GFK-TVF-BJI TO BE ON DRY SIDE OF THINGS AND SHOULD KEEP HIGH END VFR CLOUD DECK WITH SOME AC/CI. WINDS WILL BE LIGHT THIS LATE AFTN BUT TURN NORTHERLY AND INCREASE TO 10 TO 20 KTS WITH SOME HIGHER GUSTS ON THURSDAY AS COLD ADVECTION INCREASES. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...WINTER WEATHER ADVISORY UNTIL 9 AM CST THURSDAY FOR NDZ006-014- 015-024-026-028>030-038-039-049-052-053. MN...WINTER WEATHER ADVISORY UNTIL 9 AM CST THURSDAY FOR MNZ003- 029>031-040. && $$ JK/RIDDLE