Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 02/22/12
AREA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
944 AM PST MON FEB 20 2012
.SYNOPSIS...
DRY CONDITIONS AND GRADUAL WARMING IS EXPECTED THROUGH THE END OF
THIS WEEK.
&&
.DISCUSSION...
A WEAK FRONTAL SYSTEM IS PUSHING SOUTH THROUGH THE CENTRAL
CALIFORNIA INTERIOR. SCANT MOISTURE ACCOMPANIES THIS FEATURE
AND CHANCES FOR ASSOCIATED PRECIPITATION ARE RATHER SLIM.
TEMPERATURES YESTERDAY BEHIND THE PREVIOUS SYSTEM RAN JUST A TAD
BELOW CLIMO AND THE ADDITIONAL PASSING SHORTWAVE WILL PROVIDE
SIMILAR CONDITIONS TODAY. THE FORECAST FOR TODAY CAN BE UPDATED TO
TRIM THE POPS...OTHERWISE NO CHANGES REQUIRED.
A REBUILDING UPPER RIDGE BEHIND THE EXITING TROUGH TOMORROW WILL
BRING DRY AND WARMING CONDITIONS THROUGH MIDWEEK. THEN MODELS
CONTINUE TO HAVE SOME DISAGREEMENT IN THE PATTERN FOR THE END OF
THE WEEK AND EARLY NEXT WEEK AS THE RIDGE BREAKS DOWN.
&&
.PREV DISCUSSION... /ISSUED 159 AM PST MON FEB 20 2012/
DISCUSSION...RADAR SHOWS THE LEADING EDGE OF THE LIGHT
PRECIPITATION NOW APPROACHING MERCED COUNTY AS IT RACES TO THE
SOUTHEAST. NOT MUCH REACHING THE GROUND WITH SACRAMENTO JUST
TRACING THUS FAR AND I EXPECT IN THE LOWER ELEVATIONS JUST TRACE
AMOUNTS WILL FALL. OVER THE SIERRA HOWEVER A FEW HUNDREDTHS MAY
FALL BEFORE THE FRONT EXITS THE REGION. THE LATEST RUC13 MODEL
SHOWS A COUPLE OF HUNDREDTHS OVER THE SIERRA THIS MORNING THEN
DRYING OUT. THE TROUGH IS THEN PROGGED TO QUICKLY MOVE INTO
SOUTHERN CALIFORNIA AND THEN A CLOSED LOW IS FORECAST TO FORM WEST
OF SAN DIEGO. MODELS ARE THEN IN VERY GOOD AGREEMENT IN PUSHING A
RIDGE AXIS ACROSS CENTRAL CALIFORNIA FROM TUESDAY NIGHT AND THEN
KEEPING THIS FEATURE IN PLACE THROUGH NEXT WEEKEND. GIVEN THIS,
DRY AND ABOVE NORMAL TEMPERATURES WILL AGAIN BE THE MAIN WEATHER
FEATURES IN THIS VERY DRY WINTER. FOR NEXT WEEKEND, THE GFS AND
ECMWF MODELS CANNOT PRODUCE A CONSISTENT OR AGREEABLE SOLUTION
AFTER THE RIDGE PATTERN BREAKS DOWN. THE LATEST ECMWF MODEL AFTER
SEVERAL RUNS OF A DRY NORTHWEST FLOW PATTERN NOW BRINGS A DEEP
TROUGH OF LOW PRESSURE INTO THE WEST COAST SUNDAY NIGHT AND MONDAY
WHILE THE GFS SUGGESTS A MUCH LESS AMPLIFIED TROUGH PASSAGE WELL
TO THE EAST. WILL KEEP THE FORECAST DRY AT THIS TIME.
&&
.AVIATION...
LOCAL MOUNTAIN OBSCURATIONS IN UPSLOPE OVER THE SOUTHERN
SIERRA NEVADA THRU 00Z TUE. OTHERWISE...VFR CONDITIONS WILL PREVAIL
ACROSS THE CENTRAL CA INTERIOR THRU 18Z TUE.
&&
.AIR QUALITY ISSUES...
NONE.
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
PUBLIC...JEB
AVN/FW...DS
SYNOPSIS...PJ
WEATHER.GOV/HANFORD
AREA FORECAST DISCUSSION
NWS EUREKA CA
840 AM PST MON FEB 20 2012
.UPDATE...
UPDATED POPS AND WX THROUGH THIS EVENING FOR LATEST TRENDS. NOT
MUCH ACTIVITY ON RADAR ATTM AND MOST OBS REPORTING ONLY OCCASIONAL
SPRINKLES OR DRIZZLE SINCE MIDNIGHT. RUC ANALYSIS/WV IMAGERY
SHOWING WE ARE IN BETWEEN SHORTWAVES WITH ANOTHER IMPULSE SET TO
IMPACT US LATER THIS AFTERNOON AND THIS EVENING. HARD TO TELL ON
WEB CAMS IN EARLY MORNING LIGHT BUT LOOKS LIKE A LIGHT COATING OF
SNOW AT OREGON MTN AND BUCKHORN. SNOW LEVELS WILL CONTINUE TO
RISE AND SFC TEMPS ARE ABOVE FREEZING AT ALL BUT THE HIGHEST
ELEVATIONS ABOVE THE MAJOR PASSES.
&&
.PREV DISCUSSION... /ISSUED 633 AM PST MON FEB 20 2012/
UPDATE...WINDS HAVE FALLEN BELOW SMALL CRAFT CRITERIA ACROSS
ALL WATERS...SO THE SMALL CRAFT ADVISORY WILL BE ALLOWED TO
EXPIRE AT 7 AM. OTHERWISE THE GOING FORECAST REMAINS ON TRACK AND
THE PREVIOUS DISCUSSION IS INCLUDED BELOW. RPA
SYNOPSIS...AN UPPER LEVEL TROUGH WILL BRING LIGHT SHOWERS TO
NORTHWEST CALIFORNIA THROUGH TONIGHT. DRY WEATHER RETURNS TUESDAY
AND CONTINUES THROUGH THE END OF THE WEEK AS A RIDGE OF HIGH
PRESSURE DOMINATES THE WEST COAST WEATHER PATTERN.
DISCUSSION.../ISSUED AT 405 AM MON FEB 20 2012/ SATELLITE SHOWS
AN UPPER LEVEL TROUGH CURRENTLY MOVING OVER THE REGION. 11:45Z
LOCAL RADAR LOOP SHOWS SCATTERED SHOWERS THAT ARE RAPIDLY
DIMINISHING. THIS IS MAINLY DUE TO AN AREA OF DRY AIR WORKING ITS
WAY INTO THE AREA FROM THE NORTHWEST. THE MAIN BAND OF
PRECIPITATION MOVED THROUGH LAST NIGHT AND IT DID NOT DROP MUCH IN
TERMS OF AMOUNTS. THIS CONTINUES THE TREND THE PAST FEW DAYS OF
THE MODELS OVERDOING QPF AMOUNTS. WOULD NOT BE SURPRISED TO SEE
THAT CONTINUE TODAY. LOWERED POPS AND QPF IN TODAY AND TONIGHT`S
FORECAST, BUT AM CONCERNED THAT BOTH MAY STILL BE OVERDONE DUE TO
WHAT WAS JUST STATED. THE POTENTIAL OF LIGHT FREEZING DRIZZLE IN
THE VALLEYS OF TRINITY COUNTY CONTINUES THIS MORNING. IT IS
BORDERLINE RIGHT NOW WITH LOW ELEVATION TEMPERATURES HOVERING
AROUND 34 TO 36 DEGREES WITH LITTLE TO NO PRECIPITATION. BUT ANY
THAT DOES DEVELOP WILL DIMINISH THIS MORNING AS SUNSHINE WARMS UP
THE VALLEY TEMPERATURES. THE SUNSHINE MAY HELP GENERATE SOME
INSTABILITY SHOWERS THIS AFTERNOON AND EVENING. THE SHOWERS WILL
DIMINISH THIS EVENING AS HEIGHTS BEGIN TO RISE. THERE MAY BE SOME
REMNANT SHOWERS ACROSS DEL NORTE COUNTY ON TUESDAY, BUT LITTLE IF
ANY QPF IS EXPECTED. UPPER LEVEL RIDGING MOVES OVER THE WEST COAST
MIDWEEK AND STAYS IN PLACE THROUGH ABOUT FRIDAY. THIS WILL BRING
THE AREA DRY WEATHER. THINGS CHANGE OVER THE WEEKEND AS THE RIDGE
MOVES TO THE EAST AND A TROUGH FORMS OVER THE WEST COAST. RAISED
THE LONG TERM POPS TO CLIMO TO REFLECT THIS.
AVIATION.../ISSUED AT 405 AM MON FEB 20 2012/ LOW CEILINGS AND
AREAS OF DRIZZLE/RAIN SHOWERS WILL BE THE RULE TODAY ACROSS MUCH
OF THE CWA. CEILINGS ARE CURRENTLY IN MVFR AT THE TAF SITES AND
SHOULD CONTINUE TO HOLD AT THESE LEVELS OR LOWER THROUGH THE DAY
INTO TONIGHT AS ONSHORE FLOW CONTINUES JUST OFF THE SURFACE.
CONFIDENCE IN SPECIFIC CEILING LEVELS IS LOW TODAY...BUT BY
TONIGHT ALL CEILINGS SHOULD FALL INTO NEAR IFR ACROSS THE INTERIOR
AND IFR/LIFR NEAR THE COAST. THE ONSHORE FLOW ALOFT SHOULD
MAINTAIN THE CHANCE OF RAIN SHOWERS ACROSS THE ENTIRE CWA AND
DRIZZLE NEAR THE COAST THROUGH THE AFTERNOON BEFORE UPPER LEVEL
LIFT MOVES EAST OF THE AREA. VISIBILITIES MAY ALSO FALL TONIGHT AS
WINDS WEAKEN AND CEILINGS DESCEND. MORE ROBUST ONSHORE FLOW WILL
DEVELOP ON TUESDAY AS SURFACE WINDS TURN ONSHORE WITH ABUNDANT LOW
LEVEL MOISTURE. THIS MAY MAKE IT DIFFICULT FOR CONDITIONS TO
IMPROVE TUESDAY NEAR THE COAST. DRIER AIR WILL INFILTRATE
MENDOCINO COUNTY POSSIBLY RESULTING IN IMPROVING CONDITIONS
THROUGH THE DAY TUESDAY AT UKI. RPA
MARINE.../ISSUED AT 405 AM MON FEB 20 2012/ SOUTHERLY WINDS
CONTINUE TO GUST OVER 25 KT ACROSS THE OUTER EDGE OF THE INNER
NORTHERN WATERS AND NORTHERN OUTER WATERS THIS MORNING AS A TROUGH
OF LOW PRESSURE CONTINUES TO HOLD JUST OFF THE COAST. THIS TROUGH
WILL WEAKEN THIS MORNING AS AN UPPER LEVEL SHORTWAVE CURRENTLY
OVER THE REGION DIVES SOUTH INTO SOUTHERN CALIFORNIA. THUS WINDS
SHOULD FALL BELOW SMALL CRAFT BY 7 AM TODAY WITH NO OTHER
HEADLINES EXPECTED THROUGH TONIGHT. WINDS WILL TURN TO OUT OF THE
NORTH ON TUESDAY AS UPPER LEVEL RIDGING BUILDS OFF THE COAST
ALLOWING SURFACE HIGH PRESSURE TO SETTLE OVER THE EASTERN PACIFIC.
AT THE SAME TIME TEMPERATURES WILL INCREASE ACROSS INTERIOR
CALIFORNIA RESULTING IN A STRENGTHENING THERMAL TROUGH. STRONG
NORTHERLIES WILL THEN DEVELOP OVER THE WATERS AS THE PRESSURE
GRADIENT STRENGTHENS. SMALL CRAFT ADVISORIES ARE
EXPECTED...POSSIBLY GALES FOR A PERIOD MID TO LATE WEEK. OVER THE
WEEKEND THE UPPER LEVEL RIDGE WILL BEGIN TO BREAK DOWN ALLOWING A
COLD FRONT TO POSSIBLY DIVE SOUTH ALONG THE COAST RESULTING IN A
REINFORCING PUSH OF NORTHERLY WINDS AS ANOTHER AREA OF SURFACE
HIGH PRESSURE BUILDS OFF THE PACIFIC NORTHWEST COAST.
NORTHWESTERLY SWELL TODAY WILL CONTINUE TO SUBSIDE INTO TUESDAY.
BY MIDWEEK ANOTHER NORTHWESTERLY LONG PERIOD SWELL WILL ARRIVE IN
THE WATERS WITH AMPLITUDES IN THE 13 TO 15 FT RANGE POSSIBLE BY
THURSDAY. CONFIDENCE IN THE ACTUAL SWELL HEIGHTS IS CURRENTLY LOW
AS THE GENERATING LOW PRESSURE SYSTEM IS STILL DEVELOPING.
REGARDLESS OF THE SWELL MAGNITUDE...AS THE NORTHERLY WINDS
INTENSIFY MIDWEEK SHORT PERIOD WIND DRIVEN SEAS WILL ALSO DEVELOP.
THUS SIGNIFICANT WAVE HEIGHTS SHOULD BE IN THE TEENS NO MATTER THE
SWELL HEIGHT THURSDAY INTO FRIDAY...ESPECIALLY ACROSS THE SOUTHERN
WATERS WHERE THE WINDS WILL BE THE STRONGEST. RPA
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
159 AM PST MON FEB 20 2012
.SYNOPSIS...
DRY CONDITIONS ARE EXPECTED THROUGH THIS WEEK WITH TEMPERATURES
INCREASING AFTER A SLIGHT EARLY COOLING TREND WITH THE PASSAGE OF A
DRY FRONT TODAY.
&&
.DISCUSSION...RADAR SHOWS THE LEADING EDGE OF THE LIGHT
PRECIPITATION NOW APPROACHING MERCED COUNTY AS IT RACES TO THE
SOUTHEAST. NOT MUCH REACHING THE GROUND WITH SACRAMENTO JUST
TRACING THUS FAR AND I EXPECT IN THE LOWER ELEVATIONS JUST TRACE
AMOUNTS WILL FALL. OVER THE SIERRA HOWEVER A FEW HUNDREDTHS MAY
FALL BEFORE THE FRONT EXITS THE REGION. THE LATEST RUC13 MODEL
SHOWS A COUPLE OF HUNDREDTHS OVER THE SIERRA THIS MORNING THEN
DRYING OUT. THE TROUGH IS THEN PROGGED TO QUICKLY MOVE INTO
SOUTHERN CALIFORNIA AND THEN A CLOSED LOW IS FORECAST TO FORM WEST
OF SAN DIEGO. MODELS ARE THEN IN VERY GOOD AGREEMENT IN PUSHING A
RIDGE AXIS ACROSS CENTRAL CALIFORNIA FROM TUESDAY NIGHT AND THEN
KEEPING THIS FEATURE IN PLACE THROUGH NEXT WEEKEND. GIVEN THIS,
DRY AND ABOVE NORMAL TEMPERATURES WILL AGAIN BE THE MAIN WEATHER
FEATURES IN THIS VERY DRY WINTER. FOR NEXT WEEKEND, THE GFS AND
ECMWF MODELS CANNOT PRODUCE A CONSISTENT OR AGREEABLE SOLUTION
AFTER THE RIDGE PATTERN BREAKS DOWN. THE LATEST ECMWF MODEL AFTER
SEVERAL RUNS OF A DRY NORTHWEST FLOW PATTERN NOW BRINGS A DEEP
TROUGH OF LOW PRESSURE INTO THE WEST COAST SUNDAY NIGHT AND MONDAY
WHILE THE GFS SUGGESTS A MUCH LESS AMPLIFIED TROUGH PASSAGE WELL
TO THE EAST. WILL KEEP THE FORECAST DRY AT THIS TIME.
&&
.AVIATION...
LOCAL MVFR CONDITIONS AND MOUNTAIN OBSCURATIONS OVER THE SOUTHERN
SIERRA NEVADA WITH LIGHT PRECIPITATION POSSIBLE BTWN 18Z SUN - 06Z
TUES. OTHERWISE...EXPECT VFR CONDITION ACROSS THE CENTRAL CALIFORNIA
INTERIOR THROUGH 12Z TUESDAY.
&&
.AIR QUALITY ISSUES...
NONE.
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
PUBLIC...DUDLEY
AVN/FW...DCH
SYNOPSIS...PJ
WEATHER.GOV/HANFORD
AREA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
155 AM PST MON FEB 20 2012
.SYNOPSIS...
DRY CONDITIONS ARE EXPECTED THROUGH THE THIS WEEK WITH TEMPERATURES
INCREASING AFTER A SLIGHT EARLY COOLING TREND WITH THE PASSAGE OF A
DRY FRONT TODAY.
&&
.DISCUSSION...RADAR SHOWS THE LEADING EDGE OF THE LIGHT
PRECIPITATION NOW APPROACHING MERCED COUNTY AS IT RACES TO THE
SOUTHEAST. NOT MUCH REACHING THE GROUND WITH SACRAMENTO JUST
TRACING THUS FAR AND I EXPECT IN THE LOWER ELEVATIONS JUST TRACE
AMOUNTS WILL FALL. OVER THE SIERRA HOWEVER A FEW HUNDREDTHS MAY
FALL BEFORE THE FRONT EXITS THE REGION. THE LATEST RUC13 MODEL
SHOWS A COUPLE OF HUNDREDTHS OVER THE SIERRA THIS MORNING THEN
DRYING OUT. THE TROUGH IS THEN PROGGED TO QUICKLY MOVE INTO
SOUTHERN CALIFORNIA AND THEN A CLOSED LOW IS FORECAST TO FORM WEST
OF SAN DIEGO. MODELS ARE THEN IN VERY GOOD AGREEMENT IN PUSHING A
RIDGE AXIS ACROSS CENTRAL CALIFORNIA FROM TUESDAY NIGHT AND THEN
KEEPING THIS FEATURE IN PLACE THROUGH NEXT WEEKEND. GIVEN THIS,
DRY AND ABOVE NORMAL TEMPERATURES WILL AGAIN BE THE MAIN WEATHER
FEATURES IN THIS VERY DRY WINTER. FOR NEXT WEEKEND, THE GFS AND
ECMWF MODELS CANNOT PRODUCE A CONSISTENT OR AGREEABLE SOLUTION
AFTER THE RIDGE PATTERN BREAKS DOWN. THE LATEST ECMWF MODEL AFTER
SEVERAL RUNS OF A DRY NORTHWEST FLOW PATTERN NOW BRINGS A DEEP
TROUGH OF LOW PRESSURE INTO THE WEST COAST SUNDAY NIGHT AND MONDAY
WHILE THE GFS SUGGESTS A MUCH LESS AMPLIFIED TROUGH PASSAGE WELL
TO THE EAST. WILL KEEP THE FORECAST DRY AT THIS TIME.
&&
.AVIATION...
LOCAL MVFR CONDITIONS AND MOUNTAIN OBSCURATIONS OVER THE SOUTHERN
SIERRA NEVADA WITH LIGHT PRECIPITATION POSSIBLE BTWN 18Z SUN - 06Z
TUES. OTHERWISE...EXPECT VFR CONDITION ACROSS THE CENTRAL CALIFORNIA
INTERIOR THROUGH 12Z TUESDAY.
&&
.AIR QUALITY ISSUES...
NONE.
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
PUBLIC...DUDLEY
AVN/FW...DCH
SYNOPSIS...PJ
WEATHER.GOV/HANFORD
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1003 PM MST SUN FEB 19 2012
.UPDATE...
ISSUED AT 1003 PM MST SUN FEB 19 2012
ADDED A WINTER WEATHER ADVISORY FOR STEAMBOAT SPRINGS AND SURROUNDING
AREAS. REPORT CAME IN OF AMOUNTS JUST OVER 6 INCHES. AS TROUGH
SWEEPS THROUGH...EXPECT SNOW TO CONTINUE.
UPDATE ISSUED AT 917 PM MST SUN FEB 19 2012
RUC13 SHOWED DOWNSLOPE FLOW OFF THE EASTERN UINTA MOUNTAINS WITH
THE PASSAGE OF THE TROUGH EARLIER THIS EVENING. DYNAMICS WANING ON
THE BACKSIDE OF THE SYSTEM AS EVIDENCED BY LACK OF ACTIVITY OVER
THE EASTERN UINTA BASIN. THEREFORE...DROPPED WINTER WEATHER
ADVISORY OVER THE AREA. DRIER AIR HAD BEGUN TO WRAP INTO THE
REMAINDER OF EASTERN UTAH AND LOWERED POPS OVER THE VALLEYS TO
REFLECT THIS. AS EXPECTED...FRONTAL PASSAGE BROUGHT A RESURGENCE
OF SNOWFALL OVER CORTEZ WHICH WAS DOWN TO 1/2 MILE IN MODERATE
SNOW AT 04Z. EXPECT SNOW TO CONTINUE TO SPREAD EAST INTO THE
DURANGO AREA AND WILL LET ADVISORIES FOR THOSE AREAS CONTINUE
THROUGH THE EXPIRATION TIME OF 07Z. OROGRAPHICS AND INSTABILITY
OVER THE MOUNTAINS WILL CONTINUE TO BRING SNOW...SO WILL LET
ADVISORIES CONTINUE THROUGH THE NIGHT IN FAVORABLE WEST AND
NORTHWEST FLOW.
UPDATE ISSUED AT 336 PM MST SUN FEB 19 2012
LATEST SHORT RANGE MODELS INDICATED ENERGY AND MOISTURE FOCUSED
OVER SOUTHWEST COLORADO THROUGH THIS EVENING. SNOWFALL WAS ALREADY
PERSISTENT AND HEAVY AT TIMES FROM KCEZ TO KDRO AND RUC13 AND
NAM12 INDICATED THAT SNOW WILL CONTINUE THROUGH THE EVENING. BASED
UPON AMOUNTS ALREADY REPORTED IN CONJUNCTION WITH AREA WEB CAMS...
FELT WINTER WEATHER ADVISORY SHOULD BE ADDED TO THOSE AREAS FOR
THE NEXT SEVERAL HOURS.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 150 PM MST SUN FEB 19 2012
MODELS CONTINUE TO ADVERTISE DEEPENING SHORTWAVE WHICH WILL MOVE
ACROSS THE AREA OVERNIGHT. GOOD Q-G FORCING AND ADEQUATE MOISTURE
OVERNIGHT WILL COMBINE TO GENERATE GOOD SNOW ACCUMULATIONS ACROSS
MOST MOUNTAIN LOCATIONS AND NORTHERN AND CENTRAL VALLEYS. MODELS
ARE ALSO SHOWING FAIRLY UNSTABLE LAPSE RATES THIS AFTERNOON AND
EARLY EVENING WHICH WILL AID IN PRECIPITATION PRODUCTION AND MAY
GENERATE SOME ISOLATED LIGHTNING OVER SOUTHERN HALF OF THE
FORECAST AREA. BEHIND THE FRONT NORTHWEST FLOW WILL DOMINATE
OVERNIGHT WITH NORTH TO WEST ASPECTS SEEING THE BEST
ACCUMULATIONS WITH TEMPERATURES COOLING INTO THE FAVORABLE
DENDRITIC GROWTH TEMPERATURE RANGE. HAVE DECIDED TO ADD DEBEQUE TO SILT
CORRIDOR INCLUDING THE PLATEAU VALLEY TO THE WINTER WEATHER
ADVISORY THROUGH TONIGHT. MODELS ARE HITTING THE GRAND MESA AREA
THE HARDEST...LATER SHIFTS NEED TO MONITOR FOR POTENTIAL UPGRADE
OF HIGHLIGHTS. EXPECT SNOWFALL TO DIMINISH FROM WEST TO EAST
ACROSS THE LOWER VALLEY AFTER MIDNIGHT...AND END ACROSS MOUNTAIN
LOCATIONS MONDAY MORNING. EXPECT LINGERING SNOW SHOWERS
ESPECIALLY ALONG THE CONTINENTAL DIVIDE...OTHERWISE COLD
TEMPERATURES WITH CLEARING SKIES ARE EXPECTED DURING THE DAY.
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 150 PM MST SUN FEB 19 2012
MODELS CONTINUE TO SHOW AN UPPER RIDGE OFF THE WEST COAST WITH AN
ASSOCIATED DOWNSTREAM TROUGH OVER THE WESTERN AND CENTRAL STATES
THIS WEEK FOR GENERALLY NORTHWESTERLY FLOW ALOFT OVER THE CENTRAL
ROCKIES. AN EMBEDDED WAVE ZIPS SOUTHEAST ACROSS THE FORECAST AREA
LATE MONDAY NIGHT AND TUESDAY FOR A CHANCE OF PRECIP. THE NORTHERN
STREAM JET NOSES INTO NORTHERN CO TUE NIGHT...AND THEN VACILLATES
BETWEEN WY AND CO THROUGH FRIDAY WHEN IT MOVES OFF TO THE EAST. THIS
PATTERN SHOULD KEEP A PERSISTENT CHANCE OF SNOW FOR THE NORTHERN CO
MTNS THROUGH FRIDAY...WITH THE BETTER CHANCES CURRENTLY LOOKING LIKE
TUESDAY NIGHT AND THEN LATE WED NIGHT-THU. THESE ARE THE TIMES WHEN
THE MODELS SHOW THE UPPER JET OVER NRN CO FOR ADDITIONAL FORCING ON
TOP OF THE NORTHWEST OROGRAPHICS. THE CENTRAL MTNS WILL HAVE A
LESSER CHANCE. MUCH OF EASTERN UT AND SOUTHWEST CO...IN CONTRAST...
SHOULD EXPERIENCE LITTLE OR NO PRECIP WITH CLEAR OR PARTLY SKIES AND
SEASONABLE TEMPS TUE THROUGH SAT.
THIS COULD BE AN INTERESTING WEEK FOR THE NORTHERN CO MTNS...FROM VAIL
NORTHWARD TO THE ELKHEAD AND PARK MTNS. THIS PATTERN OF PERSISTENT
MOIST NW FLOW COULD LEAD TO AN EXTENDED PERIOD OF SNOW FOR THE NRN
MTNS. WHILE SNOWFALL MAY NOT BE PARTICULARLY HEAVY FOR ANY
PARTICULAR PERIOD...OVER TIME SIGNIFICANT ACCUMULATIONS ARE
POSSIBLE. ADD TO THAT SOME GUSTY W TO NW MOUNTAIN WINDS AT TIMES AS
THE JET WAVERS IN AND OUT OF NORTHERN CO.
A PROGRESSIVE PATTERN CONTINUES NEXT WEEK WHEN ANOTHER PACIFIC TROUGH
WORKING INLAND ON SAT AND LOOKS TO CROSS ERN UT/WRN CO ABOUT
SUNDAY.
&&
.AVIATION...(FOR THE 03Z TAFS THROUGH 03Z MONDAY EVENING)
ISSUED AT 917 PM MST SUN FEB 19 2012
THE COLD FRONT ASSOCIATED WITH THIS STORM WILL PUSH THROUGH THE
REMAINDER OF WESTERN COLORADO THROUGH THE EARLY EVENING HOURS
TONIGHT. AHEAD OF THE FRONT EXPECT GUSTY SOUTHWEST WINDS FROM 15
TO 25 MPH WITH GUSTS TO 45 MPH OVER THE HIGHER TERRAIN...
ESPECIALLY ON NORTH-FACING SLOPES AHEAD OF THE FRONT. WINDS WILL
SHIFT TO THE NORTHWEST AND DECREASE BEHIND THE FRONT. GUSTY WINDS
AHEAD OF THE FRONT WILL RESULT IN MODERATE MECHANICAL TURBULENCE
IN THE VICINITY OF MOUNTAINS. SNOW WILL REMAIN WIDESPREAD ACROSS
THE MOUNTAINS TONIGHT RESULTING IN EXTENSIVE OBSCURATION. LOWER
ELEVATION AIRPORTS ARE LIKELY TO EXPERIENCE MVFR CONDITIONS WITH
AREAS OF IFR CONDITIONS THIS EVENING. MOUNTAIN AIRPORTS WILL SEE
WIDESPREAD IFR CONDITIONS OVERNIGHT WITH SNOW DIMINISHING MONDAY
MORNING. VFR CONDITIONS WILL RETURN TO THE AREA MONDAY AFTERNOON
...THOUGH A FEW SNOW SHOWERS WILL LINGER OVER THE CONTINENTAL
DIVIDE DURING THE AFTERNOON RESULTING IN LOCALIZED MOUNTAIN
OBSCURATIONS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL 8 AM MST MONDAY FOR COZ001>005-007-
009-010-012-013-017>019-023.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST TONIGHT FOR COZ021-
022.
UT...WINTER WEATHER ADVISORY UNTIL 8 AM MST MONDAY FOR UTZ023-025.
&&
$$
UPDATE...NL
SHORT TERM...MPM
LONG TERM....JAD
AVIATION...NL
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
917 PM MST SUN FEB 19 2012
.UPDATE...
ISSUED AT 917 PM MST SUN FEB 19 2012
RUC13 SHOWED DOWNSLOPE FLOW OFF THE EASTERN UINTA MOUNTAINS WITH
THE PASSAGE OF THE TROUGH EARLIER THIS EVENING. DYNAMICS WANING ON
THE BACKSIDE OF THE SYSTEM AS EVIDENCED BY LACK OF ACTIVITY OVER
THE EASTERN UINTA BASIN. THEREFORE...DROPPED WINTER WEATHER
ADVISORY OVER THE AREA. DRIER AIR HAD BEGUN TO WRAP INTO THE
REMAINDER OF EASTERN UTAH AND LOWERED POPS OVER THE VALLEYS TO
REFLECT THIS. AS EXPECTED...FRONTAL PASSAGE BROUGHT A RESURGENCE
OF SNOWFALL OVER CORTEZ WHICH WAS DOWN TO 1/2 MILE IN MODERATE
SNOW AT 04Z. EXPECT SNOW TO CONTINUE TO SPREAD EAST INTO THE
DURANGO AREA AND WILL LET ADVISORIES FOR THOSE AREAS CONTINUE
THROUGH THE EXPIRATION TIME OF 07Z. OROGRAPHICS AND INSTABILITY
OVER THE MOUNTAINS WILL CONTINUE TO BRING SNOW...SO WILL LET
ADVISORIES CONTINUE THROUGH THE NIGHT IN FAVORABLE WEST AND
NORTHWEST FLOW.
UPDATE ISSUED AT 336 PM MST SUN FEB 19 2012
LATEST SHORT RANGE MODELS INDICATED ENERGY AND MOISTURE FOCUSED
OVER SOUTHWEST COLORADO THROUGH THIS EVENING. SNOWFALL WAS ALREADY
PERSISTENT AND HEAVY AT TIMES FROM KCEZ TO KDRO AND RUC13 AND
NAM12 INDICATED THAT SNOW WILL CONTINUE THROUGH THE EVENING. BASED
UPON AMOUNTS ALREADY REPORTED IN CONJUNCTION WITH AREA WEB CAMS...
FELT WINTER WEATHER ADVISORY SHOULD BE ADDED TO THOSE AREAS FOR
THE NEXT SEVERAL HOURS.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 150 PM MST SUN FEB 19 2012
MODELS CONTINUE TO ADVERTISE DEEPENING SHORTWAVE WHICH WILL MOVE
ACROSS THE AREA OVERNIGHT. GOOD Q-G FORCING AND ADEQUATE MOISTURE
OVERNIGHT WILL COMBINE TO GENERATE GOOD SNOW ACCUMULATIONS ACROSS
MOST MOUNTAIN LOCATIONS AND NORTHERN AND CENTRAL VALLEYS. MODELS
ARE ALSO SHOWING FAIRLY UNSTABLE LAPSE RATES THIS AFTERNOON AND
EARLY EVENING WHICH WILL AID IN PRECIPITATION PRODUCTION AND MAY
GENERATE SOME ISOLATED LIGHTNING OVER SOUTHERN HALF OF THE
FORECAST AREA. BEHIND THE FRONT NORTHWEST FLOW WILL DOMINATE
OVERNIGHT WITH NORTH TO WEST ASPECTS SEEING THE BEST
ACCUMULATIONS WITH TEMPERATURES COOLING INTO THE FAVORABLE
DENDRITIC GROWTH TEMPERATURE RANGE. HAVE DECIDED TO ADD DEBEQUE TO SILT
CORRIDOR INCLUDING THE PLATEAU VALLEY TO THE WINTER WEATHER
ADVISORY THROUGH TONIGHT. MODELS ARE HITTING THE GRAND MESA AREA
THE HARDEST...LATER SHIFTS NEED TO MONITOR FOR POTENTIAL UPGRADE
OF HIGHLIGHTS. EXPECT SNOWFALL TO DIMINISH FROM WEST TO EAST
ACROSS THE LOWER VALLEY AFTER MIDNIGHT...AND END ACROSS MOUNTAIN
LOCATIONS MONDAY MORNING. EXPECT LINGERING SNOW SHOWERS
ESPECIALLY ALONG THE CONTINENTAL DIVIDE...OTHERWISE COLD
TEMPERATURES WITH CLEARING SKIES ARE EXPECTED DURING THE DAY.
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 150 PM MST SUN FEB 19 2012
MODELS CONTINUE TO SHOW AN UPPER RIDGE OFF THE WEST COAST WITH AN
ASSOCIATED DOWNSTREAM TROUGH OVER THE WESTERN AND CENTRAL STATES
THIS WEEK FOR GENERALLY NORTHWESTERLY FLOW ALOFT OVER THE CENTRAL
ROCKIES. AN EMBEDDED WAVE ZIPS SOUTHEAST ACROSS THE FORECAST AREA
LATE MONDAY NIGHT AND TUESDAY FOR A CHANCE OF PRECIP. THE NORTHERN
STREAM JET NOSES INTO NORTHERN CO TUE NIGHT...AND THEN VACILLATES
BETWEEN WY AND CO THROUGH FRIDAY WHEN IT MOVES OFF TO THE EAST. THIS
PATTERN SHOULD KEEP A PERSISTENT CHANCE OF SNOW FOR THE NORTHERN CO
MTNS THROUGH FRIDAY...WITH THE BETTER CHANCES CURRENTLY LOOKING LIKE
TUESDAY NIGHT AND THEN LATE WED NIGHT-THU. THESE ARE THE TIMES WHEN
THE MODELS SHOW THE UPPER JET OVER NRN CO FOR ADDITIONAL FORCING ON
TOP OF THE NORTHWEST OROGRAPHICS. THE CENTRAL MTNS WILL HAVE A
LESSER CHANCE. MUCH OF EASTERN UT AND SOUTHWEST CO...IN CONTRAST...
SHOULD EXPERIENCE LITTLE OR NO PRECIP WITH CLEAR OR PARTLY SKIES AND
SEASONABLE TEMPS TUE THROUGH SAT.
THIS COULD BE AN INTERESTING WEEK FOR THE NORTHERN CO MTNS...FROM VAIL
NORTHWARD TO THE ELKHEAD AND PARK MTNS. THIS PATTERN OF PERSISTENT
MOIST NW FLOW COULD LEAD TO AN EXTENDED PERIOD OF SNOW FOR THE NRN
MTNS. WHILE SNOWFALL MAY NOT BE PARTICULARLY HEAVY FOR ANY
PARTICULAR PERIOD...OVER TIME SIGNIFICANT ACCUMULATIONS ARE
POSSIBLE. ADD TO THAT SOME GUSTY W TO NW MOUNTAIN WINDS AT TIMES AS
THE JET WAVERS IN AND OUT OF NORTHERN CO.
A PROGRESSIVE PATTERN CONTINUES NEXT WEEK WHEN ANOTHER PACIFIC TROUGH
WORKING INLAND ON SAT AND LOOKS TO CROSS ERN UT/WRN CO ABOUT
SUNDAY.
&&
.AVIATION...(FOR THE 03Z TAFS THROUGH 03Z MONDAY EVENING)
ISSUED AT 917 PM MST SUN FEB 19 2012
THE COLD FRONT ASSOCIATED WITH THIS STORM WILL PUSH THROUGH THE
REMAINDER OF WESTERN COLORADO THROUGH THE EARLY EVENING HOURS
TONIGHT. AHEAD OF THE FRONT EXPECT GUSTY SOUTHWEST WINDS FROM 15
TO 25 MPH WITH GUSTS TO 45 MPH OVER THE HIGHER TERRAIN...
ESPECIALLY ON NORTH-FACING SLOPES AHEAD OF THE FRONT. WINDS WILL
SHIFT TO THE NORTHWEST AND DECREASE BEHIND THE FRONT. GUSTY WINDS
AHEAD OF THE FRONT WILL RESULT IN MODERATE MECHANICAL TURBULENCE
IN THE VICINITY OF MOUNTAINS. SNOW WILL REMAIN WIDESPREAD ACROSS
THE MOUNTAINS TONIGHT RESULTING IN EXTENSIVE OBSCURATION. LOWER
ELEVATION AIRPORTS ARE LIKELY TO EXPERIENCE MVFR CONDITIONS WITH
AREAS OF IFR CONDITIONS THIS EVENING. MOUNTAIN AIRPORTS WILL SEE
WIDESPREAD IFR CONDITIONS OVERNIGHT WITH SNOW DIMINISHING MONDAY
MORNING. VFR CONDITIONS WILL RETURN TO THE AREA MONDAY AFTERNOON
...THOUGH A FEW SNOW SHOWERS WILL LINGER OVER THE CONTINENTAL
DIVIDE DURING THE AFTERNOON RESULTING IN LOCALIZED MOUNTAIN
OBSCURATIONS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL 8 AM MST MONDAY FOR COZ001>004-007-
009-010-012-013-017>019-023.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST TONIGHT FOR COZ021-
022.
UT...WINTER WEATHER ADVISORY UNTIL 8 AM MST MONDAY FOR UTZ023-025.
&&
$$
UPDATE...NL
SHORT TERM...MPM
LONG TERM....JAD
AVIATION...NL
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
341 PM CST MON FEB 20 2012
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 235 PM CST MON FEB 20 2012
FORECAST CONCERNS ARE THE SNOW AND HIGH WINDS LATE THIS AFTERNOON
INTO EARLY EVENING. THIS MORNINGS UA ANALYSIS SHOWED A STRONG
UPPER TROUGH ALONG THE EASTERN SLOPES OF THE ROCKIES WITH A CLOSED
CIRCULATION SHOWING UP OVER NORTHEAST COLORADO. THIS FEATURE HAS BEEN
MOVING STEADILY EAST THROUGH WESTERN KANSAS AND THE OK/TX PANHANDLES
THIS AFTERNOON. RUC ANALYSIS SHOWED A FAIRLY INTENSE MID LEVEL
VORT MAX ACROSS THE AREA WITH STRONG PVA AND MID LEVEL UVV OCCURRING
OVER SOUTHWEST KANSAS. THIS LINES UP WELL WITH AN AREA OF LIGHT
TO MODERATE SNOW WHICH HAS BEEN TRANSLATING EAST THROUGH SOUTHWEST
KANSAS TODAY.
THE AREAS OF RAIN AND SNOW SHOULD CONTINUE TO WORK EASTWARD ACROSS
SOUTHWEST AND TOWARD CENTRAL KANSAS THROUGH THE LATE AFTERNOON
HOURS BUT SHOULD BEGIN TO DIMINISH RAPIDLY TOWARD SUNSET AS THE
TROUGH AXIS MOVES EAST OF THE AREA.
HIGH WINDS HAVE BEEN SLOW TO MATERIALIZE ACROSS SOUTHWEST KANSAS
THIS AFTERNOON PARTLY DUE TO THE WIDESPREAD CLOUD COVER AND
REDUCED MIXING. AM STILL CONCERNED THAT WE COULD SEE A WINDOW OF
OPPORTUNITY AS THE GRADIENT INCREASES ON THE BACKSIDE OF THE LOWER
ATMOSPHERIC TROUGH AXIS. RUC MODEL SOUNDINGS THROUGHOUT THE DAY
HAVE BEEN SHOWING 50-60 KNOT WINDS DEVELOPING IN THE 850-875 MB
LAYER THROUGH THE 21Z-01Z TIME PERIOD. WILL KEEP THE CURRENT
HEADLINES IN PLACE THROUGH THE EARLY EVENING HOURS.
THE UPPER LEVEL SHORTWAVE TROUGH WILL MOVE RAPIDLY EAST OUT OF THE
PLAINS TONIGHT WITH WESTERLY FLOW OVER THE HIGH PLAINS. ANOTHER
BROAD SHORTWAVE TROUGH IS FORECAST TO MOVE SOUTHEAST OVER THE
CENTRAL CONUS DURING THE DAY TUESDAY. ONLY SOME SCATTERED HIGH
CLOUDINESS IS EXPECTED WITH THE SHORTWAVE. LOW LEVEL DOWNSLOPE
FLOW SHOULD HELP BOOST TEMPERATURES INTO THE 55 TO 60 DEGREE RANGE
FOR AFTERNOON HIGHS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 351 AM CST MON FEB 20 2012
MEDIUM RANGE MODELS INDICATE AN UPPER LEVEL TROUGH OF LOW PRESSURE
IN THE FAR INTERMOUNTAIN WEST DROPPING SOUTH INTO THE BAJA
CALIFORNIA REGION EARLY IN THE PERIOD TUESDAY. MEANWHILE, A WEST TO
NORTHWESTERLY FLOW ALOFT WILL PREVAIL ACROSS THE WESTERN HIGH PLAINS
DURING THE FIRST COUPLE DAYS OF THE PERIOD ALONG WITH A WESTERLY
DOWNSLOPE REGIME PERSISTING NEAR THE SURFACE HELPING TO DRY OUT THE
LOWER LEVELS. AS A RESULT, DRY CONDITIONS ARE LIKELY THROUGH AT LEAST
WEDNESDAY NIGHT. THE UPPER LEVEL TROUGH IN THE DESERT SOUTHWEST IS
THEN PROJECTED TO TRACK EASTWARD INTO THE SOUTH PLAINS OF TEXAS BY
THURSDAY JUST AS A SECONDARY UPPER LEVEL SHORTWAVE DROPS SOUTHEAST
OUT OF CANADA INTO THE NORTHERN PLAINS. THE NORTHERN WAVE WILL HELP
USHER A COLD FRONT SOUTH INTO WESTERN KANSAS SOMETIME LATE WEDNESDAY
NIGHT INTO EARLY THURSDAY. HOWEVER, VERY LITTLE IS EXPECTED IN
REGARDS TO PRECIP WITH THIS FRONTAL PASSAGE WITH A LACK OF LOW LEVEL
MOISTURE REMAINING A FACTOR.
TEMPERATURES ARE EXPECTED TO BE NEAR NORMAL TUESDAY AS A WEAK LEE
SIDE TROUGH INFLUENCES A WESTERLY DOWNSLOPE FLOW ACROSS WESTERN
KANSAS. THE NAM, GFS, AND ECMWF SHOW H85 TEMPERATURES RANGING FROM
AROUND 5C ACROSS CENTRAL KANSAS TO NEAR 8C ALONG THE COLORADO
BORDER. LOOK FOR HIGHS WELL UP INTO THE 50S(F) TUESDAY AFTERNOON
WITH NEAR 60F POSSIBLE IN SOUTH CENTRAL KANSAS. TEMPERATURES WILL
CLIMB GOING INTO WEDNESDAY AS THE WESTERLY DOWNSLOPE COMPONENT NEAR
THE SURFACE CONTINUES ACROSS WESTERN KANSAS. TEMPERATURES AT H85
WILL WARM TO AROUND 12C ACROSS CENTRAL KANSAS TO NEAR 15C IN EXTREME
SOUTHWEST KANSAS. EXPECT WIDESPREAD 60S(F) WEDNESDAY WITH NEAR
70F POSSIBLE IN SOME LOCATIONS. WILL NEED TO RAISE HIGHS ON
WEDNESDAY BY AT LEAST 3 TO 5 DEGREES ACROSS THE ENTIRE FORECAST
AREA. COOLER TEMPERATURES ARE THEN LIKELY THURSDAY INTO FRIDAY IN
WAKE OF THE PROJECTED FRONTAL PASSAGE BY EARLY THURSDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1215 PM CST MON FEB 20 2012
MVFR CIGS WILL CONTINUE AT GARDEN CITY THIS AFTERNOON AND WILL
DEVELOP AT DODGE CITY AND HAYS AS THE AFTERNOON CONTINUES. LIGHT
SNOW COULD REDUCE VISIBILITIES AT GARDEN CITY INTO THE 3-5 MILE
RANGE AFTER 20Z. WINDS WILL ALSO INCREASE TO SUSTAINED SPEEDS OF
25 TO 35 KNOTS WITH GUSTS TO 45-50 KNOTS POSSIBLE ESPECIALLY AT
GARDEN CITY AND DODGE CITY. CIGS AND VSBYS SHOULD IMPROVE RAPIDLY
FROM WEST TO EAST BY AROUND 00Z AND WINDS WILL DIMINISH BY SUNSET.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 22 58 30 70 / 30 0 0 0
GCK 20 56 28 69 / 20 0 0 0
EHA 21 57 33 70 / 10 0 0 0
LBL 21 58 30 70 / 10 0 0 0
HYS 25 56 30 69 / 30 0 0 0
P28 27 60 32 72 / 30 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 7 PM CST /6 PM MST/ THIS EVENING FOR
KSZ030-043>045-061>064-074>078-084>088.
WIND ADVISORY UNTIL 10 PM CST THIS EVENING FOR KSZ031-046-065-
066-079>081-089-090.
&&
$$
SHORT TERM...GERARD
LONG TERM....JJOHNSON
AVIATION...GERARD
AREA FORECAST DISCUSSION
NWS WICHITA KS
211 PM CST MON FEB 20 2012
.DISCUSSION...
FORECAST CONCERNS...CONVECTIVE TRENDS THRU EARLY EVENING AND
THEN TEMPERATURE ROLLER-COASTER THRU THE END OF THE WEEK.
THIS EVENING/OVERNIGHT
LATEST RUC AND HRRR WOULD SUGGEST 700-900 J/KG CAPE NEAR MAX
HEATING LATE THIS AFTERNOON JUST AHEAD OF SURFACE DRY-LINE/COLD
FRONT ACROSS SOUTH CENTRAL KANSAS. THIS IN COMBO WITH STRONG
DEEP LAYER SHEAR WILL SUPPORT STRONG TO A FEW SEVERE STORMS
INTO THE EARLY EVENING TRANSITIONING FROM PORTIONS OF CENTRAL
AND SOUTH CENTRAL KANSAS ACROSS THE SOUTHERN FLINT HILLS. SEE
LATEST HAZARDOUS WEATHER OUTLOOK AND SHORT TERM GRAPHICAST FOR
MORE DETAILS.
OTHERWISE...WINDS SHOULD REMAIN STOUT EVEN BEHIND THE FRONT
THIS EVENING...NEAR ADVISORY THRESHOLDS...SO 06Z/MIDNIGHT
EXPIRATION LOOKS FINE.
TUESDAY-FRIDAY
A RATHER SIGNIFICANT WARMING TREND IS EXPECTED THROUGH THE
MID-WEEK PERIOD WITHIN THE DEVELOPING MEAN WESTERLY FLOW
AHEAD OF THE NEXT UPPER TROF. THIS SUPPORTS THE GOING MAXS...
APPROACHING 70F IN MANY AREAS ON WEDNESDAY. THIS WILL BE
FOLLOWED BY A MODERATE STRENGTH COLD FRONT ON THURSDAY WITH
TEMPERATURES CLOSER TO SEASONAL CLIMO FOR THE END OF THE WEEK.
SATURDAY-MONDAY
A MORE ZONAL UPPER FLOW PATTERN TO START OUT THE WEEKEND
WITH TEMPERATURES AGAIN MODERATING ABOVE SEASONAL CLIMO. THE
MEDIUM RANGE MODELS GENERALLY SUPPORT MEAN TROUGHING ALOFT
ACROSS THE WESTERN CONUS LATE IN THE PERIOD...WITH THE ECMWF
A BIT DEEPER WITH THIS TROF BY MONDAY. THE MAIN CHALLENGE IS
THE TIMING OF THE ASSOCIATED COLD FRONTAL BOUNDARY SOUTH
ACROSS THE PLAINS...AND POTENTIAL OF SIGNIFICANT COOLING
BEHIND THIS FRONT. FOR NOW FORECAST CONSENSUS WAS TO TREND
COOLER BY MONDAY...THOUGH CONFIDENCE IS RATHER LOW ON THE
MAGNITUDE...WITH POTENTIAL FOR MUCH COLDER AIR. WILL ALSO
CARRY SLIGHT TO MODEST POPS ALONG/JUST BEHIND THIS SOUTHWARD
SAGGING FRONT FOR NOW WHICH CAN BE REFINED WITH LATER RUNS.
DARMOFAL
&&
.AVIATION...18Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
MVFR CIGS WILL HANG TOUGH THROUGH AT LEAST MID-
AFTERNOON...ALTHOUGH SOME CLEARING FROM THE WEST IS EXPECTED AS A
STRONG COLD FRONT CONTINUES TO APPROACH FROM THE WEST. AHEAD OF
THE FRONT...VERY STRONG/GUSTY SOUTHERLY WINDS WILL PREVAIL.
ADDITIONALLY...SCATTERED THUNDERSTORMS SHOULD DEVELOP AROUND
20-21Z JUST WEST OF THE I-135 CORRIDOR. STORM MOTION WILL BE TO
THE NORTHEAST AT 50-60 MPH. A FEW STORMS WILL LIKELY PRODUCE SMALL
TO MODERATE SIZE HAIL UP TO DIME/QUARTER SIZE...ALONG WITH GUSTY
WINDS. THE STORMS WILL MOVE RAPIDLY NORTHEAST...WITH VERY STRONG
WEST/NORTHWEST WINDS DEVELOPING BY EARLY THIS EVENING BEHIND THE
COLD FRONT SWEEPING EAST ACROSS THE AREA...ALONG WITH MVFR TO LOW
VFR CIGS. CIGS AND WINDS WILL DISSIPATE BY LATE EVENING FROM WEST
TO EAST...CLEARING KCNU LAST.
KLEINSASSER
&&
.FIRE WEATHER...
STRONG WINDS WILL CONTINUE TO ELEVATE FIRE DANGER THROUGH THE
EVENING ACROSS MUCH OF THE AREA. DRIER AIR AND DIURNALLY GUSTY
WINDS MAY LEAD TO PERIODS OF ELEVATED FIRE DANGER DURING THE
AFTERNOON HOURS FROM TUESDAY THROUGH THURSDAY.
KED
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 28 57 33 68 / 20 0 0 0
HUTCHINSON 27 57 32 69 / 20 0 0 0
NEWTON 29 56 34 68 / 20 0 0 0
ELDORADO 30 56 34 67 / 30 0 0 0
WINFIELD-KWLD 29 58 33 69 / 20 0 0 0
RUSSELL 26 56 32 69 / 30 0 0 0
GREAT BEND 26 56 32 69 / 30 0 0 0
SALINA 28 57 33 69 / 30 0 0 0
MCPHERSON 28 57 33 68 / 30 0 0 0
COFFEYVILLE 33 59 34 69 / 60 0 0 0
CHANUTE 32 57 34 67 / 60 0 0 0
IOLA 32 56 34 66 / 60 0 0 0
PARSONS-KPPF 33 58 34 68 / 60 0 0 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR KSZ032-033-047>053-
067>070-082-083-091>094-098.
&&
$$
AREA FORECAST DISCUSSION
NWS WICHITA KS
1158 AM CST MON FEB 20 2012
.UPDATE...
STILL THINKING SCATTERED THUNDERSTORMS WILL DEVELOP AROUND 2PM
GENERALLY ALONG THE HIGHWAY 14 CORRIDOR AS MID-LEVEL COOLING
ASSOCIATED WITH APPROACHING STRONG SHORTWAVE OVERSPREADS A NARROW
LOW-LEVEL WARM SECTOR AHEAD OF A STRONG COLD FRONT/DRYLINE.
DESPITE DEWPOINTS ONLY IN THE 40S AND DENSE CLOUDS...MODEST TO
PERHAPS STRONG HEATING IN WAKE OF DEPARTING CLOUD SHIELD AND JUST
AHEAD OF THE FRONTAL ZONE...IN CONCERT WITH STRONG MID-LEVEL
COOLING SHOULD SUPPORT A NARROW ZONE OF SURFACE-BASED INSTABILITY
UP TO 500 J/KG BY MID-AFTERNOON. SHORT-TERM MODELS HAVE A GOOD
HANDLE ON THIS. PAST SEVERAL RUNS OF THE HRRR-3KM MODEL HAVE
CONSISTENTLY DEVELOPED CONVECTION ALONG THE HIGHWAY 14 CORRIDOR BY
2PM...SPREADING THIS ACTIVITY RAPIDLY EAST THROUGH THE
AFTERNOON/EVENING. DESPITE THE MARGINAL INSTABILITY...EFFECTIVE
SHEAR OF 40-50KTS IN CONCERT WITH STRONG FORCING SHOULD ALLOW FOR
A FEW STRONG TO MARGINALLY SEVERE STORMS CAPABLE OF DIME-QUARTER
HAIL AND 50-60 MPH WINDS. ADDITIONALLY...MODEST LOW-LEVEL SHEAR
COUPLED WITH HINTS OF DEVELOPING 0-3KM INSTABILITY COULD RESULT IN
A FEW BRIEF/SMALL FUNNEL CLOUDS...ALTHOUGH CLIMATOLOGICALLY ITS
VERY HARD TO GET TORNADOES WITH DEWPOINTS BELOW 50 DEGREES.
KLEINSASSER
&&
.AVIATION...18Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
MVFR CIGS WILL HANG TOUGH THROUGH AT LEAST MID-
AFTERNOON...ALTHOUGH SOME CLEARING FROM THE WEST IS EXPECTED AS A
STRONG COLD FRONT CONTINUES TO APPROACH FROM THE WEST. AHEAD OF
THE FRONT...VERY STRONG/GUSTY SOUTHERLY WINDS WILL PREVAIL.
ADDITIONALLY...SCATTERED THUNDERSTORMS SHOULD DEVELOP AROUND
20-21Z JUST WEST OF THE I-135 CORRIDOR. STORM MOTION WILL BE TO
THE NORTHEAST AT 50-60 MPH. A FEW STORMS WILL LIKELY PRODUCE SMALL
TO MODERATE SIZE HAIL UP TO DIME/QUARTER SIZE...ALONG WITH GUSTY
WINDS. THE STORMS WILL MOVE RAPIDLY NORTHEAST...WITH VERY STRONG
WEST/NORTHWEST WINDS DEVELOPING BY EARLY THIS EVENING BEHIND THE
COLD FRONT SWEEPING EAST ACROSS THE AREA...ALONG WITH MVFR TO LOW
VFR CIGS. CIGS AND WINDS WILL DISSIPATE BY LATE EVENING FROM WEST
TO EAST...CLEARING KCNU LAST.
KLEINSASSER
&&
.PREV DISCUSSION... /ISSUED 556 AM CST MON FEB 20 2012/
AVIATION...12Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
MAIN AVIATION CONCERNS WILL BE LOWER CIGS THIS MORNING...STRONG
WINDS ALONG WITH CONVECTIVE CHANCES LATE THIS AFTERNOON AND EVENING.
STRONG LOW PRESSURE IS EXPECTED TO MOVE OUT INTO THE PLAINS TODAY.
AHEAD OF THIS SYSTEM SOUTH WINDS WILL BE QUITE STRONG ACROSS ALL TAF
SITES FROM LATE THIS MORNING THROUGH THE AFTERNOON HOURS. AN AREA OF
LOWER CIGS CURRENTLY STRETCHES ALONG AND WEST OF I-135 AND IS
PROGRESSING EAST. WHILE CONFIDENCE IS HIGH THAT THESE CIGS WILL NOT
DROP TO IFR LEVELS...FEEL THEY WILL BOUNCE BETWEEN MVFR AND VFR FOR
MOST OF THE MORNING.
SHOWERS AND STORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG THE
COLD FRONT/DRYLINE. THIS ACTIVITY SHOULD DEVELOP ALONG OR JUST WEST
OF I-135 AFTER 18Z AND WILL RAPIDLY PUSH EAST. WHILE WIDESPREAD
SEVERE STORMS ARE NOT EXPECTED...A FEW OF THE STRONGER CELLS MAY
PRODUCE NICKEL TO QUARTER SIZE HAIL.
AS THIS STRONG LOW PRESSURE SYSTEM CONTINUES TO PUSH EAST...STRONG
WEST AND NORTHWEST WINDS WILL MOVE-IN FROM THE WEST AFTER 00Z AND
WILL BE SUSTAINED AROUND 35 MPH WITH GUSTS BETWEEN 40 AND 45 MPH.
THESE HIGH WIND SPEEDS WILL DIE OFF AROUND 06Z.
LAWSON
PREV DISCUSSION... /ISSUED 339 AM CST MON FEB 20 2012/
DISCUSSION...
THE MAIN FORECAST CONCERN/CHALLENGE IS PRECIPITATION AND WINDS TODAY
ASSOCIATED WITH THE POTENT LOW PRESSURE SYSTEM MOVING ACROSS
KANSAS.
SYNOPSIS:
A DEEP TROUGH IS MOVING ACROSS THE CENTRAL CONUS THIS MORNING AND
WILL BE THE MAIN WEATHER SYSTEM IMPACTING THE AREA TODAY. AT THE
SURFACE A LOW IS DEEPENING IN THE LEE OF THE ROCKIES WITH STRONG
SOUTHERLY GRADIENT WINDS ACROSS WESTERN KANSAS AHEAD OF THE LOW.
SOME SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS HAVE DEVELOPED
AHEAD OF THE SURFACE LOW IN THE WARM AIR ADVECTION REGIME.
TODAY - TONIGHT:
THIS WILL BE THE TRICKIEST PERIOD OF THE FORECAST. THE SURFACE LOW
WILL TRACK EASTWARD ACROSS CENTRAL KANSAS TODAY. THE PRESSURE
GRADIENT WINDS ASSOCIATED WITH THE DEEP LOW WILL CAUSE WINDS TO HOWL
ACROSS THE AREA. SOUTHERLY WINDS WILL BE STRONG DURING THE DAY WITH
WARM AIR ADVECTION AND HAVE KEPT THE CURRENT WIND ADVISORY IN
PLACE. HOWEVER...DID ADD RUSSELL AND BARTON COUNTIES TO THE
ADVISORY WITH THE CONCERN ABOUT STRONG WINDS BEHIND THE COLD FRONT.
THE PRESSURE GRADIENT IS JUST AS STRONG AND DESPITE THE FACT THAT IT
WILL BE MOVING THROUGH NEAR TO AFTER SUNSET THE GRADIENT WINDS WILL
KEEP THE BOUNDARY LAYER MIXED. SO HAVE ALSO EXTENDED THE ADVISORY
TIME FROM UNTIL 06Z. THE ONE WIND ADVISORY WILL COVER BOTH THE
STRONG SOUTH WINDS AND STRONG NORTHWEST WINDS AS WE DECIDED TO KEEP
ONE ADVISORY INSTEAD OF TRYING TO SEPARATE IT AND CONFUSE PEOPLE.
BOTTOM LINE IT IS GOING TO BE VERY WINDY TODAY.
THE NEXT MAIN CHALLENGE IS THE CHANCES FOR SHOWERS AND THUNDERSTORMS
TODAY. AN AREA OF SHOWERS AND ISOLATED THUNDERSTORMS IS MOVING
ACROSS CENTRAL KANSAS AND THE HRRR HAS HAD A REALLY GOOD HANDLE ON
IT SINCE THE 03/04Z RUN. THE LATER HRRR RUNS ARE SOMEWHAT IN LINE
WITH WHAT THE NAM HINTS AT...KEEPING THE MAIN PRECIPITATION SHOW
LATER IN THE DAY ACROSS CENTRAL AND SOUTHERN KANSAS. THE 06Z/HRRR
ALBEIT A LITTLE BULLISH ON THE INTENSITY SHOWS THE LINE OF
PRECIPITATION MOVING NORTHEAST ACROSS THE AREA THIS MORNING WITH THE
WARM AIR ADVECTION/MOISTURE TRANSPORT. THEN AFTER IT MOVES THROUGH
IT KEEPS THE FORECAST DRY UNTIL LATER THIS AFTERNOON...MUCH LIKE THE
NAM IS SHOWING. HAVE TRIED TO TREND THAT WAY WITH POPS...DECREASING
THEM EARLIER IN THE DAY AND INCREASING THEM TOWARD THE AFTERNOON.
THE NAM ALSO INDICATES THAT THE DRYSLOT WILL TRY TO MOVE INTO SOUTH
CENTRAL KANSAS. THIS WILL HELP TEMPERATURES AND THUNDERSTORM
POTENTIAL AS THE COLD FRONT/DRY LINE MOVES THROUGH THIS AFTERNOON.
LOW LEVEL ML AND MU CAPE INDICATE ABOUT 500-1000 J/KG POSSIBLE
AROUND 21Z ACROSS SOUTH CENTRAL KANSAS. THE POSSIBILITY FOR LOW
TOPPED THUNDERSTORMS AND POSSIBLY SOME ISOLATED SEVERE THUNDERSTORMS
ARE POSSIBLE THIS AFTERNOON. SEVERE HAIL AND WINDS ARE POSSIBLE IN A
FEW ISOLATED EVENTS...BUT WIDESPREAD SEVERE ACTIVITY IS NOT
ANTICIPATED AT THIS TIME.
TUESDAY - WEDNESDAY:
THE PATTERN CALMS SOME AFTER TODAY DESPITE A COUPLE MORE UPPER LEVEL
DISTURBANCES MOVING ACROSS. HOWEVER THE MAIN ENERGY WILL STAY NORTH
WHICH WILL KEEP SKIES MOSTLY CLEAR. THE COLD FRONT TODAY WILL SWEEP
ALL MOISTURE SOUTHWARD KEEPING IT DRY. LOW LEVEL WESTERLY WINDS
WILL BE PRESENT ACROSS THE AREA BOTH DAYS AND ALTHOUGH THEY WILL NOT
BE SUPER STRONG...10-15 MPH WINDS...MOSTLY CLEAR SKIES AND DOWNSLOPE
WILL HELP TEMPERATURES WARM TO WELL ABOVE NORMAL. INCREASED
TEMPERATURES BOTH TUESDAY AND WEDNESDAY...BUT MORE DRASTICALLY
WEDNESDAY WITH TEMPERATURES IN THE MID 60S POSSIBLE ACROSS THE
AREA.
THURSDAY - FRIDAY:
BY THURSDAY THE NEXT FRONT WILL MOVE ACROSS THE REGION. HAVE KEPT
THE FORECAST DRY FOR NOW...BUT THE LATEST 00Z/ECMWF DOES HINT AT THE
POSSIBILITY OF SOME PRECIPITATION. CONFIDENCE IS LOW OF ANY
PRECIPITATION WITH THE LACK OF ANY RETURN FLOW DURING THE WEEK. THE
FRONT WILL AT THE MINIMUM SHIFT THE WINDS TO THE NORTHWEST AND LOWER
TEMPERATURES BACK NEARER TO NORMAL...IN THE UPPER 40S.
SATURDAY - SUNDAY:
THE MEDIUM RANGE GUIDANCE SOLUTIONS BEGINS TO DIVERGE BY THE END OF
THE WEEK. AFTER THE WAVE THAT MOVES THROUGH FRIDAY...THEY INDICATE
UPPER LEVEL RIDGING WITH THE NEXT WAVE MOVING IN BY THE END OF THE
FORECAST. THE GFS IS MUCH MORE PROGRESSIVE WITH THE NEXT SYSTEM
DIVING IN FROM THE NORTHWEST. THE GUIDANCE DOES SHOW A POTENT
SYSTEM MOVING THROUGH SUNDAY AND INTO MONDAY...BEYOND THIS
FORECAST...BUT BECAUSE OF THE DRASTIC DIFFERENCES IN TIMING...HAVE
KEPT THE FORECAST DRY AND TEMPERATURES AT MODEL CONSENSUS WHICH IS
IN THE LOW 50S. STAY TUNED AS THE FORECAST EVOLVE.
BILLINGS
FIRE WEATHER...
FIRE WEATHER WILL BE A CONCERN TODAY ACROSS THE WHOLE AREA WITH THE
GRASSLAND FIRE DANGER INDEX REACHING INTO VERY HIGH AND APPROACHING
EXTREME OVER SOUTH CENTRAL KANSAS. SOUTHERLY WINDS WILL BE VERY
STRONG THROUGHOUT THE DAY AHEAD OF THE COLD FRONT. WE HAVE A WIND
ADVISORY IN EFFECT WHICH MEANS THAT WINDS WILL BE SUSTAINED AROUND
30 MPH WITH GUSTS NEAR 40 MPH. WINDS WILL THEN SWITCH TO THE
NORTHWEST AS THE FRONT MOVES THROUGH AND WILL THEN BE 30-35 MPH WITH
GUSTS NEAR 40-45 MPH. THERE WILL BE A CHANCE OF PRECIPITATION
THROUGHOUT THE DAY...BUT THE WINDS WILL CAUSE ANY FIRE THAT STARTS
TO QUICKLY BECOME DANGEROUS.
BILLINGS
AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
AS HAS BEEN THE CASE OVER THE LAST COUPLE OF WEEKS...MODELS STRUGGLED
WITH LOW LEVEL MOISTURE. 0000 UTC RUNS LOOK A BIT BETTER THAN THE
18Z ONES...ESPECIALLY WITH RUC/NAM/HRRR BEING MORE GENEROUS WITH
LOW LEVEL MOISTURE. THIS TRANSLATES TO EARLIER/MORE EXTENSIVE
CLOUDS...WITH VERY HIGH LIKELIHOOD OF MVFR AND SOME CHANCE OF IFR
CONDITIONS...ESPECIALLY AT KRSL/KHUT. PRECIPITATION TIMING IS A
BIT UNCERTAIN...WITH ONE DECENT IMPULSE MOVING THROUGH IN A FEW
HOURS PER WATER VAPOR LOOP...AND THEN MORE ASSOCIATED WITH
FAVORABLE DIFFLUENCE/SPEED MAXIMUM AHEAD OF UPPER TROUGH. SO
SUSPECT ISOLATED/SCATTERED RAIN SHOWERS WILL REDEVELOP/LINGER INTO
LATE MORNING AT KSLN/KHUT/KICT. PRECIPITATION CHANCES AT KCNU LOOK
A BIT LOW TO INCLUDE AT THIS TIME. DRY SLOT WILL WORK ACROSS THE
AREA DURING THE AFTERNOON...WITH LOW CLOUDS/GUSTY WEST-NORTHWEST
WINDS BEHIND THE FRONT IN THE EVENING. -HOWERTON
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 56 28 58 34 / 50 20 0 0
HUTCHINSON 56 28 58 34 / 50 20 0 0
NEWTON 54 29 57 35 / 60 20 0 0
ELDORADO 55 30 57 34 / 60 30 0 0
WINFIELD-KWLD 57 29 59 34 / 60 20 0 0
RUSSELL 54 27 57 33 / 40 30 0 10
GREAT BEND 56 26 57 33 / 30 30 0 10
SALINA 56 28 59 34 / 50 30 0 0
MCPHERSON 55 28 59 34 / 50 30 0 0
COFFEYVILLE 56 33 59 36 / 50 60 10 10
CHANUTE 55 33 58 35 / 50 60 10 0
IOLA 54 32 58 36 / 50 60 10 0
PARSONS-KPPF 56 33 59 34 / 50 60 10 10
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR KSZ032-033-047>053-
067>070-082-083-091>094-098.
&&
$$
AREA FORECAST DISCUSSION
NWS WICHITA KS
556 AM CST MON FEB 20 2012
.AVIATION...12Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
MAIN AVIATION CONCERNS WILL BE LOWER CIGS THIS MORNING...STRONG
WINDS ALONG WITH CONVECTIVE CHANCES LATE THIS AFTERNOON AND EVENING.
STRONG LOW PRESSURE IS EXPECTED TO MOVE OUT INTO THE PLAINS TODAY.
AHEAD OF THIS SYSTEM SOUTH WINDS WILL BE QUITE STRONG ACROSS ALL TAF
SITES FROM LATE THIS MORNING THROUGH THE AFTERNOON HOURS. AN AREA OF
LOWER CIGS CURRENTLY STRETCHES ALONG AND WEST OF I-135 AND IS
PROGRESSING EAST. WHILE CONFIDENCE IS HIGH THAT THESE CIGS WILL NOT
DROP TO IFR LEVELS...FEEL THEY WILL BOUNCE BETWEEN MVFR AND VFR FOR
MOST OF THE MORNING.
SHOWERS AND STORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG THE
COLD FRONT/DRYLINE. THIS ACTIVITY SHOULD DEVELOP ALONG OR JUST WEST
OF I-135 AFTER 18Z AND WILL RAPIDLY PUSH EAST. WHILE WIDESPREAD
SEVERE STORMS ARE NOT EXPECTED...A FEW OF THE STRONGER CELLS MAY
PRODUCE NICKEL TO QUARTER SIZE HAIL.
AS THIS STRONG LOW PRESSURE SYSTEM CONTINUES TO PUSH EAST...STRONG
WEST AND NORTHWEST WINDS WILL MOVE-IN FROM THE WEST AFTER 00Z AND
WILL BE SUSTAINED AROUND 35 MPH WITH GUSTS BETWEEN 40 AND 45 MPH.
THESE HIGH WIND SPEEDS WILL DIE OFF AROUND 06Z.
LAWSON
&&
.PREV DISCUSSION... /ISSUED 339 AM CST MON FEB 20 2012/
DISCUSSION...
THE MAIN FORECAST CONCERN/CHALLENGE IS PRECIPITATION AND WINDS TODAY
ASSOCIATED WITH THE POTENT LOW PRESSURE SYSTEM MOVING ACROSS
KANSAS.
SYNOPSIS:
A DEEP TROUGH IS MOVING ACROSS THE CENTRAL CONUS THIS MORNING AND
WILL BE THE MAIN WEATHER SYSTEM IMPACTING THE AREA TODAY. AT THE
SURFACE A LOW IS DEEPENING IN THE LEE OF THE ROCKIES WITH STRONG
SOUTHERLY GRADIENT WINDS ACROSS WESTERN KANSAS AHEAD OF THE LOW.
SOME SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS HAVE DEVELOPED
AHEAD OF THE SURFACE LOW IN THE WARM AIR ADVECTION REGIME.
TODAY - TONIGHT:
THIS WILL BE THE TRICKIEST PERIOD OF THE FORECAST. THE SURFACE LOW
WILL TRACK EASTWARD ACROSS CENTRAL KANSAS TODAY. THE PRESSURE
GRADIENT WINDS ASSOCIATED WITH THE DEEP LOW WILL CAUSE WINDS TO HOWL
ACROSS THE AREA. SOUTHERLY WINDS WILL BE STRONG DURING THE DAY WITH
WARM AIR ADVECTION AND HAVE KEPT THE CURRENT WIND ADVISORY IN
PLACE. HOWEVER...DID ADD RUSSELL AND BARTON COUNTIES TO THE
ADVISORY WITH THE CONCERN ABOUT STRONG WINDS BEHIND THE COLD FRONT.
THE PRESSURE GRADIENT IS JUST AS STRONG AND DESPITE THE FACT THAT IT
WILL BE MOVING THROUGH NEAR TO AFTER SUNSET THE GRADIENT WINDS WILL
KEEP THE BOUNDARY LAYER MIXED. SO HAVE ALSO EXTENDED THE ADVISORY
TIME FROM UNTIL 06Z. THE ONE WIND ADVISORY WILL COVER BOTH THE
STRONG SOUTH WINDS AND STRONG NORTHWEST WINDS AS WE DECIDED TO KEEP
ONE ADVISORY INSTEAD OF TRYING TO SEPARATE IT AND CONFUSE PEOPLE.
BOTTOM LINE IT IS GOING TO BE VERY WINDY TODAY.
THE NEXT MAIN CHALLENGE IS THE CHANCES FOR SHOWERS AND THUNDERSTORMS
TODAY. AN AREA OF SHOWERS AND ISOLATED THUNDERSTORMS IS MOVING
ACROSS CENTRAL KANSAS AND THE HRRR HAS HAD A REALLY GOOD HANDLE ON
IT SINCE THE 03/04Z RUN. THE LATER HRRR RUNS ARE SOMEWHAT IN LINE
WITH WHAT THE NAM HINTS AT...KEEPING THE MAIN PRECIPITATION SHOW
LATER IN THE DAY ACROSS CENTRAL AND SOUTHERN KANSAS. THE 06Z/HRRR
ALBEIT A LITTLE BULLISH ON THE INTENSITY SHOWS THE LINE OF
PRECIPITATION MOVING NORTHEAST ACROSS THE AREA THIS MORNING WITH THE
WARM AIR ADVECTION/MOISTURE TRANSPORT. THEN AFTER IT MOVES THROUGH
IT KEEPS THE FORECAST DRY UNTIL LATER THIS AFTERNOON...MUCH LIKE THE
NAM IS SHOWING. HAVE TRIED TO TREND THAT WAY WITH POPS...DECREASING
THEM EARLIER IN THE DAY AND INCREASING THEM TOWARD THE AFTERNOON.
THE NAM ALSO INDICATES THAT THE DRYSLOT WILL TRY TO MOVE INTO SOUTH
CENTRAL KANSAS. THIS WILL HELP TEMPERATURES AND THUNDERSTORM
POTENTIAL AS THE COLD FRONT/DRY LINE MOVES THROUGH THIS AFTERNOON.
LOW LEVEL ML AND MU CAPE INDICATE ABOUT 500-1000 J/KG POSSIBLE
AROUND 21Z ACROSS SOUTH CENTRAL KANSAS. THE POSSIBILITY FOR LOW
TOPPED THUNDERSTORMS AND POSSIBLY SOME ISOLATED SEVERE THUNDERSTORMS
ARE POSSIBLE THIS AFTERNOON. SEVERE HAIL AND WINDS ARE POSSIBLE IN A
FEW ISOLATED EVENTS...BUT WIDESPREAD SEVERE ACTIVITY IS NOT
ANTICIPATED AT THIS TIME.
TUESDAY - WEDNESDAY:
THE PATTERN CALMS SOME AFTER TODAY DESPITE A COUPLE MORE UPPER LEVEL
DISTURBANCES MOVING ACROSS. HOWEVER THE MAIN ENERGY WILL STAY NORTH
WHICH WILL KEEP SKIES MOSTLY CLEAR. THE COLD FRONT TODAY WILL SWEEP
ALL MOISTURE SOUTHWARD KEEPING IT DRY. LOW LEVEL WESTERLY WINDS
WILL BE PRESENT ACROSS THE AREA BOTH DAYS AND ALTHOUGH THEY WILL NOT
BE SUPER STRONG...10-15 MPH WINDS...MOSTLY CLEAR SKIES AND DOWNSLOPE
WILL HELP TEMPERATURES WARM TO WELL ABOVE NORMAL. INCREASED
TEMPERATURES BOTH TUESDAY AND WEDNESDAY...BUT MORE DRASTICALLY
WEDNESDAY WITH TEMPERATURES IN THE MID 60S POSSIBLE ACROSS THE
AREA.
THURSDAY - FRIDAY:
BY THURSDAY THE NEXT FRONT WILL MOVE ACROSS THE REGION. HAVE KEPT
THE FORECAST DRY FOR NOW...BUT THE LATEST 00Z/ECMWF DOES HINT AT THE
POSSIBILITY OF SOME PRECIPITATION. CONFIDENCE IS LOW OF ANY
PRECIPITATION WITH THE LACK OF ANY RETURN FLOW DURING THE WEEK. THE
FRONT WILL AT THE MINIMUM SHIFT THE WINDS TO THE NORTHWEST AND LOWER
TEMPERATURES BACK NEARER TO NORMAL...IN THE UPPER 40S.
SATURDAY - SUNDAY:
THE MEDIUM RANGE GUIDANCE SOLUTIONS BEGINS TO DIVERGE BY THE END OF
THE WEEK. AFTER THE WAVE THAT MOVES THROUGH FRIDAY...THEY INDICATE
UPPER LEVEL RIDGING WITH THE NEXT WAVE MOVING IN BY THE END OF THE
FORECAST. THE GFS IS MUCH MORE PROGRESSIVE WITH THE NEXT SYSTEM
DIVING IN FROM THE NORTHWEST. THE GUIDANCE DOES SHOW A POTENT
SYSTEM MOVING THROUGH SUNDAY AND INTO MONDAY...BEYOND THIS
FORECAST...BUT BECAUSE OF THE DRASTIC DIFFERENCES IN TIMING...HAVE
KEPT THE FORECAST DRY AND TEMPERATURES AT MODEL CONSENSUS WHICH IS
IN THE LOW 50S. STAY TUNED AS THE FORECAST EVOLVE.
BILLINGS
FIRE WEATHER...
FIRE WEATHER WILL BE A CONCERN TODAY ACROSS THE WHOLE AREA WITH THE
GRASSLAND FIRE DANGER INDEX REACHING INTO VERY HIGH AND APPROACHING
EXTREME OVER SOUTH CENTRAL KANSAS. SOUTHERLY WINDS WILL BE VERY
STRONG THROUGHOUT THE DAY AHEAD OF THE COLD FRONT. WE HAVE A WIND
ADVISORY IN EFFECT WHICH MEANS THAT WINDS WILL BE SUSTAINED AROUND
30 MPH WITH GUSTS NEAR 40 MPH. WINDS WILL THEN SWITCH TO THE
NORTHWEST AS THE FRONT MOVES THROUGH AND WILL THEN BE 30-35 MPH WITH
GUSTS NEAR 40-45 MPH. THERE WILL BE A CHANCE OF PRECIPITATION
THROUGHOUT THE DAY...BUT THE WINDS WILL CAUSE ANY FIRE THAT STARTS
TO QUICKLY BECOME DANGEROUS.
BILLINGS
AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
AS HAS BEEN THE CASE OVER THE LAST COUPLE OF WEEKS...MODELS STRUGGLED
WITH LOW LEVEL MOISTURE. 0000 UTC RUNS LOOK A BIT BETTER THAN THE
18Z ONES...ESPECIALLY WITH RUC/NAM/HRRR BEING MORE GENEROUS WITH
LOW LEVEL MOISTURE. THIS TRANSLATES TO EARLIER/MORE EXTENSIVE
CLOUDS...WITH VERY HIGH LIKELIHOOD OF MVFR AND SOME CHANCE OF IFR
CONDITIONS...ESPECIALLY AT KRSL/KHUT. PRECIPITATION TIMING IS A
BIT UNCERTAIN...WITH ONE DECENT IMPULSE MOVING THROUGH IN A FEW
HOURS PER WATER VAPOR LOOP...AND THEN MORE ASSOCIATED WITH
FAVORABLE DIFFLUENCE/SPEED MAXIMUM AHEAD OF UPPER TROUGH. SO
SUSPECT ISOLATED/SCATTERED RAIN SHOWERS WILL REDEVELOP/LINGER INTO
LATE MORNING AT KSLN/KHUT/KICT. PRECIPITATION CHANCES AT KCNU LOOK
A BIT LOW TO INCLUDE AT THIS TIME. DRY SLOT WILL WORK ACROSS THE
AREA DURING THE AFTERNOON...WITH LOW CLOUDS/GUSTY WEST-NORTHWEST
WINDS BEHIND THE FRONT IN THE EVENING. -HOWERTON
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 56 28 58 34 / 60 20 0 0
HUTCHINSON 55 28 58 34 / 50 20 0 0
NEWTON 54 29 57 35 / 60 20 0 0
ELDORADO 57 30 57 34 / 60 20 0 0
WINFIELD-KWLD 57 29 59 34 / 60 20 0 0
RUSSELL 56 27 57 33 / 50 20 0 10
GREAT BEND 56 26 57 33 / 50 20 0 10
SALINA 55 28 59 34 / 60 30 0 0
MCPHERSON 55 28 59 34 / 60 20 0 0
COFFEYVILLE 60 33 59 36 / 60 40 10 10
CHANUTE 55 33 58 35 / 60 50 10 0
IOLA 55 32 58 36 / 60 50 10 0
PARSONS-KPPF 58 33 59 34 / 60 40 10 10
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 9 AM THIS MORNING TO MIDNIGHT CST TONIGHT FOR
KSZ032-033-047>053-067>070-082-083-091>094-098.
&&
$$
AREA FORECAST DISCUSSION
NWS WICHITA KS
339 AM CST MON FEB 20 2012
.DISCUSSION...
THE MAIN FORECAST CONCERN/CHALLENGE IS PRECIPITATION AND WINDS TODAY
ASSOCIATED WITH THE POTENT LOW PRESSURE SYSTEM MOVING ACROSS KANSAS.
SYNOPSIS:
A DEEP TROUGH IS MOVING ACROSS THE CENTRAL CONUS THIS MORNING AND
WILL BE THE MAIN WEATHER SYSTEM IMPACTING THE AREA TODAY. AT THE
SURFACE A LOW IS DEEPENING IN THE LEE OF THE ROCKIES WITH STRONG
SOUTHERLY GRADIENT WINDS ACROSS WESTERN KANSAS AHEAD OF THE LOW.
SOME SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS HAVE DEVELOPED
AHEAD OF THE SURFACE LOW IN THE WARM AIR ADVECTION REGIME.
TODAY - TONIGHT:
THIS WILL BE THE TRICKIEST PERIOD OF THE FORECAST. THE SURFACE LOW
WILL TRACK EASTWARD ACROSS CENTRAL KANSAS TODAY. THE PRESSURE
GRADIENT WINDS ASSOCIATED WITH THE DEEP LOW WILL CAUSE WINDS TO HOWL
ACROSS THE AREA. SOUTHERLY WINDS WILL BE STRONG DURING THE DAY WITH
WARM AIR ADVECTION AND HAVE KEPT THE CURRENT WIND ADVISORY IN
PLACE. HOWEVER...DID ADD RUSSELL AND BARTON COUNTIES TO THE
ADVISORY WITH THE CONCERN ABOUT STRONG WINDS BEHIND THE COLD FRONT.
THE PRESSURE GRADIENT IS JUST AS STRONG AND DESPITE THE FACT THAT IT
WILL BE MOVING THROUGH NEAR TO AFTER SUNSET THE GRADIENT WINDS WILL
KEEP THE BOUNDARY LAYER MIXED. SO HAVE ALSO EXTENDED THE ADVISORY
TIME FROM UNTIL 06Z. THE ONE WIND ADVISORY WILL COVER BOTH THE
STRONG SOUTH WINDS AND STRONG NORTHWEST WINDS AS WE DECIDED TO KEEP
ONE ADVISORY INSTEAD OF TRYING TO SEPARATE IT AND CONFUSE PEOPLE.
BOTTOM LINE IT IS GOING TO BE VERY WINDY TODAY.
THE NEXT MAIN CHALLENGE IS THE CHANCES FOR SHOWERS AND THUNDERSTORMS
TODAY. AN AREA OF SHOWERS AND ISOLATED THUNDERSTORMS IS MOVING
ACROSS CENTRAL KANSAS AND THE HRRR HAS HAD A REALLY GOOD HANDLE ON
IT SINCE THE 03/04Z RUN. THE LATER HRRR RUNS ARE SOMEWHAT IN LINE
WITH WHAT THE NAM HINTS AT...KEEPING THE MAIN PRECIPITATION SHOW
LATER IN THE DAY ACROSS CENTRAL AND SOUTHERN KANSAS. THE 06Z/HRRR
ALBEIT A LITTLE BULLISH ON THE INTENSITY SHOWS THE LINE OF
PRECIPITATION MOVING NORTHEAST ACROSS THE AREA THIS MORNING WITH THE
WARM AIR ADVECTION/MOISTURE TRANSPORT. THEN AFTER IT MOVES THROUGH
IT KEEPS THE FORECAST DRY UNTIL LATER THIS AFTERNOON...MUCH LIKE THE
NAM IS SHOWING. HAVE TRIED TO TREND THAT WAY WITH POPS...DECREASING
THEM EARLIER IN THE DAY AND INCREASING THEM TOWARD THE AFTERNOON.
THE NAM ALSO INDICATES THAT THE DRYSLOT WILL TRY TO MOVE INTO SOUTH
CENTRAL KANSAS. THIS WILL HELP TEMPERATURES AND THUNDERSTORM
POTENTIAL AS THE COLD FRONT/DRY LINE MOVES THROUGH THIS AFTERNOON.
LOW LEVEL ML AND MU CAPE INDICATE ABOUT 500-1000 J/KG POSSIBLE
AROUND 21Z ACROSS SOUTH CENTRAL KANSAS. THE POSSIBILITY FOR LOW
TOPPED THUNDERSTORMS AND POSSIBLY SOME ISOLATED SEVERE THUNDERSTORMS
ARE POSSIBLE THIS AFTERNOON. SEVERE HAIL AND WINDS ARE POSSIBLE IN A
FEW ISOLATED EVENTS...BUT WIDESPREAD SEVERE ACTIVITY IS NOT
ANTICIPATED AT THIS TIME.
TUESDAY - WEDNESDAY:
THE PATTERN CALMS SOME AFTER TODAY DESPITE A COUPLE MORE UPPER LEVEL
DISTURBANCES MOVING ACROSS. HOWEVER THE MAIN ENERGY WILL STAY NORTH
WHICH WILL KEEP SKIES MOSTLY CLEAR. THE COLD FRONT TODAY WILL SWEEP
ALL MOISTURE SOUTHWARD KEEPING IT DRY. LOW LEVEL WESTERLY WINDS
WILL BE PRESENT ACROSS THE AREA BOTH DAYS AND ALTHOUGH THEY WILL NOT
BE SUPER STRONG...10-15 MPH WINDS...MOSTLY CLEAR SKIES AND DOWNSLOPE
WILL HELP TEMPERATURES WARM TO WELL ABOVE NORMAL. INCREASED
TEMPERATURES BOTH TUESDAY AND WEDNESDAY...BUT MORE DRASTICALLY
WEDNESDAY WITH TEMPERATURES IN THE MID 60S POSSIBLE ACROSS THE
AREA.
THURSDAY - FRIDAY:
BY THURSDAY THE NEXT FRONT WILL MOVE ACROSS THE REGION. HAVE KEPT
THE FORECAST DRY FOR NOW...BUT THE LATEST 00Z/ECMWF DOES HINT AT THE
POSSIBILITY OF SOME PRECIPITATION. CONFIDENCE IS LOW OF ANY
PRECIPITATION WITH THE LACK OF ANY RETURN FLOW DURING THE WEEK. THE
FRONT WILL AT THE MINIMUM SHIFT THE WINDS TO THE NORTHWEST AND LOWER
TEMPERATURES BACK NEARER TO NORMAL...IN THE UPPER 40S.
SATURDAY - SUNDAY:
THE MEDIUM RANGE GUIDANCE SOLUTIONS BEGINS TO DIVERGE BY THE END OF
THE WEEK. AFTER THE WAVE THAT MOVES THROUGH FRIDAY...THEY INDICATE
UPPER LEVEL RIDGING WITH THE NEXT WAVE MOVING IN BY THE END OF THE
FORECAST. THE GFS IS MUCH MORE PROGRESSIVE WITH THE NEXT SYSTEM
DIVING IN FROM THE NORTHWEST. THE GUIDANCE DOES SHOW A POTENT
SYSTEM MOVING THROUGH SUNDAY AND INTO MONDAY...BEYOND THIS
FORECAST...BUT BECAUSE OF THE DRASTIC DIFFERENCES IN TIMING...HAVE
KEPT THE FORECAST DRY AND TEMPERATURES AT MODEL CONSENSUS WHICH IS
IN THE LOW 50S. STAY TUNED AS THE FORECAST EVOLVE.
BILLINGS
&&
.FIRE WEATHER...
FIRE WEATHER WILL BE A CONCERN TODAY ACROSS THE WHOLE AREA WITH THE
GRASSLAND FIRE DANGER INDEX REACHING INTO VERY HIGH AND APPROACHING
EXTREME OVER SOUTH CENTRAL KANSAS. SOUTHERLY WINDS WILL BE VERY
STRONG THROUGHOUT THE DAY AHEAD OF THE COLD FRONT. WE HAVE A WIND
ADVISORY IN EFFECT WHICH MEANS THAT WINDS WILL BE SUSTAINED AROUND
30 MPH WITH GUSTS NEAR 40 MPH. WINDS WILL THEN SWITCH TO THE
NORTHWEST AS THE FRONT MOVES THROUGH AND WILL THEN BE 30-35 MPH WITH
GUSTS NEAR 40-45 MPH. THERE WILL BE A CHANCE OF PRECIPITATION
THROUGHOUT THE DAY...BUT THE WINDS WILL CAUSE ANY FIRE THAT STARTS
TO QUICKLY BECOME DANGEROUS.
BILLINGS
&&
.AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
AS HAS BEEN THE CASE OVER THE LAST COUPLE OF WEEKS...MODELS STRUGGLED
WITH LOW LEVEL MOISTURE. 0000 UTC RUNS LOOK A BIT BETTER THAN THE
18Z ONES...ESPECIALLY WITH RUC/NAM/HRRR BEING MORE GENEROUS WITH
LOW LEVEL MOISTURE. THIS TRANSLATES TO EARLIER/MORE EXTENSIVE
CLOUDS...WITH VERY HIGH LIKELIHOOD OF MVFR AND SOME CHANCE OF IFR
CONDITIONS...ESPECIALLY AT KRSL/KHUT. PRECIPITATION TIMING IS A
BIT UNCERTAIN...WITH ONE DECENT IMPULSE MOVING THROUGH IN A FEW
HOURS PER WATER VAPOR LOOP...AND THEN MORE ASSOCIATED WITH
FAVORABLE DIFFLUENCE/SPEED MAXIMUM AHEAD OF UPPER TROUGH. SO
SUSPECT ISOLATED/SCATTERED RAIN SHOWERS WILL REDEVELOP/LINGER INTO
LATE MORNING AT KSLN/KHUT/KICT. PRECIPITATION CHANCES AT KCNU LOOK
A BIT LOW TO INCLUDE AT THIS TIME. DRY SLOT WILL WORK ACROSS THE
AREA DURING THE AFTERNOON...WITH LOW CLOUDS/GUSTY WEST-NORTHWEST
WINDS BEHIND THE FRONT IN THE EVENING. -HOWERTON
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 56 28 58 34 / 60 20 0 0
HUTCHINSON 55 28 58 34 / 50 20 0 0
NEWTON 54 29 57 35 / 60 20 0 0
ELDORADO 57 30 57 34 / 60 20 0 0
WINFIELD-KWLD 57 29 59 34 / 60 20 0 0
RUSSELL 56 27 57 33 / 50 20 0 10
GREAT BEND 56 26 57 33 / 50 20 0 10
SALINA 55 28 59 34 / 60 30 0 0
MCPHERSON 55 28 59 34 / 60 20 0 0
COFFEYVILLE 60 33 59 36 / 60 40 10 10
CHANUTE 55 33 58 35 / 60 50 10 0
IOLA 55 32 58 36 / 60 50 10 0
PARSONS-KPPF 58 33 59 34 / 60 40 10 10
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 9 AM THIS MORNING TO MIDNIGHT CST TONIGHT FOR
KSZ032-033-047>053-067>070-082-083-091>094-098.
&&
$$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1236 PM CST MON FEB 20 2012
.UPDATE...
ISSUED AT 1235 PM CST MON FEB 20 2012
MIDDAY UPDATE FOR 18Z ROUTINE TAF ISSUANCE AND SHORT TERM
MODIFICATIONS TO WEATHER FOR LATE TONIGHT AND EARLY TUESDAY
/MAINLY MIDNIGHT THROUGH NOON ON TUESDAY/
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 1235 PM CST MON FEB 20 2012
THE VERY NEAR TERM CHALLENGES FOR TODAY HAVE BEEN ACCOUNTING FOR
SLOWER SURFACE DEWPOINT CHANGES /DRIER AIR/ MIXING ACROSS THE
BOUNDARY LAYER THIS AFTERNOON. MINOR MODIFICATIONS WERE MADE USING
THE 12KM NAM-WRF AND 3KM HRRR GUIDANCE...ADJUSTING THE THE NAM-WRF
GUIDANCE DOWN BETWEEN 1-3 DEGREES THIS AFTERNOON.
THE FOR LATE TONIGHT THROUGH EARLY TUESDAY...THE MAIN CHALLENGE
THIS MORNING AND CONTINUES TO BE THIS AFTERNOON THE DEGREE OF
ELEVATED INSTABILITY IN PLACE WITH THE NEGATIVELY TILTED SHORTWAVE
AND THE AVAILABLE DEEP LAYER MOISTURE...BOTH WHICH ARE SOMEWHAT
LIMITED. UTILIZING THE MOST UNSTABLE SHORT RANGE MODEL /12KM NAM-
WRF/...CAPE VALUES NEAR OR ABOVE 100 /JOULES/KG/E-2 WILL ONLY BE
NOTED IN A SMALL WINDOW OVER SOUTHEAST IL/SOUTHWEST IN/NORTHWEST
KY BETWEEN 10-14Z AT MOST. WILL NEED TO ADDRESS THAT FOR THE MID-
AFTERNOON SHORT TERM UPDATE.
.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 325 AM CST MON FEB 20 2012
THURSDAY INTO FRIDAY...THE IMMEDIATE FORECAST AREA WILL BE UNDER
THE INFLUENCE OF A DEEP MID LEVEL TROUGH FORECAST TO PIVOT FROM
THE CENTRAL U.S. MID WEEK TO THE EAST COAST BY THE WEEKEND. GFS...
ECMWF...AND GEM ARE ALL IN GENERAL AGREEMENT WITH REGARD TO THE
OVERALL PATTERN...AND THIS LENDS INCREASED CONFIDENCE TO THE
LATTER HALF OF THE FORECAST.
STARTING WITH THURSDAY...THE POTENTIAL FOR RAIN SHOWERS WILL BE ON
THE INCREASE BY AFTERNOON AS LOW PRESSURE DRAGS A COLD FRONT INTO
THE QUAD STATE REGION BY LATE AFTERNOON. STRONG SOUTHERLY FLOW OUT
AHEAD OF THIS FEATURE WILL RESULT IN ANOTHER WARM DAY...AS HIGHS ARE
FORECAST TO TOP OUT IN THE MID 60S...POSSIBLY EVEN WARMER DEPENDING
ON THE DEGREE OF INSOLATION. SHOWER CHANCES WILL INCREASE MARKEDLY
THURSDAY NIGHT AS THE COLD FRONT MAKES ITS WAY ACROSS THE REGION.
SHOWALTER AND K INDICES SUGGEST ENOUGH ELEVATED INSTABILITY TO ADD
A SLIGHT CHANCE THUNDER MENTION TO THE SOUTHERN PENNYRILE AREA OF
WESTERN KENTUCKY.
FRIDAY IS A BIT UNCERTAIN AT THIS TIME...AND WILL LARGELY DEPEND ON
HOW QUICKLY THE WEATHER SYSTEM SHIFTS EAST OF THE AREA. FOR NOW...
LINGERED SMALL RAIN CHANCES MAINLY EAST OF THE MISSISSIPPI RIVER.
TEMPERATURES DURING THIS ENTIRE TIME WILL BE WAY TOO WARM FOR
ANYTHING OTHER THAN RAIN. BEHIND THE FRONT...TEMPERATURES WILL DROP
TO NEAR OR SLIGHTLY BELOW NORMAL FRIDAY. THIS WILL CONTINUE INTO
SATURDAY AS THE SURFACE HIGH SETTLES OVERHEAD. RETURN SOUTHERLY FLOW
ON SUNDAY WILL MAKE FOR WINDY CONDITIONS AND ALLOW TEMPERATURES TO
CLIMB BACK ABOVE NORMAL. AT THIS TIME...IT APPEARS AS THOUGH ANY
SHOWER ACTIVITY WILL HOLD OFF UNTIL SUNDAY NIGHT AS THE NEXT WEATHER
SYSTEM DRAWS CLOSER.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1235 PM CST MON FEB 20 2012
CHALLENGE WAS THE TIMING OF CLOUD COVER AND POTENTIAL FOR SHOWERS
OVERNIGHT INTO EARLY TUESDAY. A SLIGHTLY TIME ADJUSTED 12Z GFS
GUIDANCE WAS USED TO MOVE CLOUDS/SHOWERS THROUGH THE AREA. THERE
DOES EXIST SOME ELEVATED INSTABILITY CLOSER TO 700 MB...SO ADDED A
MENTION OF CB DURING THE 06-13Z TUESDAY TIME FRAME IN THE
TAFS. THE PROBABILITY OF THUNDERSTORMS APPEARED TO BE TOO LOW TO
WARRANT A MENTION AT THIS TIME IN ANY OF THE TAFS. THE GFS
APPEARED TO SATURATE THE LOW LEVELS QUICKLY AFTER 09Z...SO HAD TO
ADD A MENTION OF MVFR CEILINGS AND VISIBILITIES AT MOST OF THE WFO
PAH TAF SITES AFTER THAT TIME.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...SMITH
SHORT TERM...SMITH
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
929 AM EST MON FEB 20 2012
.SYNOPSIS...
HIGH PRESSURE WILL MOVE ACROSS THE UPPER OHIO VALLEY AND PROVIDE
DRY WEATHER INTO EARLY TUESDAY. A COLD FRONT WILL CROSS THE REGION
TUESDAY BRINGING RAIN TO THE AREA. A SHARP COLD DOWN IS SLATED FOR
THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
STRATOCU DOWNWIND OF LAKE ERIE IS ERODING RAPIDLY OVER WRN PA.
THIS IS LINE WITH THE LATEST HRRR BL RH PROGS. EXPECT CLOUDS OVER
ECNTRL OHIO TO LINGER INTO THE LUNCH HOUR...BEFORE OWING TO MSNNY
CONDITIONS. TEMPERATURES ON TRACK WITH LATEST GRIDDED LAMP THUS NO
CHANGES NECESSARY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
ANOTHER OPEN WAVE TROUGH IS PROGGED TO SWING ALONG THE OHIO
VALLEY TUESDAY AND NORTHEAST INTO NEW ENGLAND TUESDAY NIGHT.
AREA OF ASSOCIATED SHOWERS IS PROGGED TO ADVANCE EAST ACROSS THE
FORECAST AREA BY TUESDAY AFTERNOON AND EXIT TO THE EAST BY LATE
TUESDAY NIGHT. WAA, AHEAD OF SYSTEM, SHOULD BOOST TEMPERATURES
ENOUGH FOR PRECIPITATION TYPE TO REMAIN IN FORM OF LIQUID AT MOST
LOCATIONS.
PRECIPITATION CHANCES SHOULD DIMINISH LATE TUESDAY NIGHT INTO
WEDNESDAY MORNING AS THE UPPER TROUGH PULLS AWAY. AN APPROACHING
COLD FRONT WILL INCREASE SHOWER COVERAGE AGAIN LATE IN THE DAY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
FORECAST PATTERN FOR THE LONG TERM PERIOD CONTS TO FEATURE DEVELOPMENT
OF A MID/UPR LOW PRESSURE CENTER TO THE SOUTH OF THE HUDSON BAY. THE
UPR OHIO VALLEY REGION WOULD THUS BE UNDER ZONAL FLOW THROUGH THE
BASE OF THE RESULTING BROAD TROUGH ACRS THE GREAT LAKES.
PRECIP PROGNOSIS WL DEPEND ON TIMING OF SHORTWAVES WITHIN THAT RAPID
FLOW...SO FORECAST THROUGH DAY 6 IS OF CHC NUMBERS THAT ARE AT OR
ABOVE CLIMATOLOGICAL NUMBERS. INITIALLY MILD TEMPERATURES WL
DECLINE THROUGH THE PERIOD AS PROGRESSING SHORTWAVES SHUNT COLDER AIR
ACROSS THE NRN TIER OF STATES AND TOWARD THE UPR OH REGION. DECISIVE
COLD FRONT IS ECMWF/GFS AGREED FOR A SATURDAY PASSAGE...HENCE A
DRY SUNDAY WAS PROGGED WITH SEASONABLY COLD TEMPERATURES.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
HIGH CONFIDENCE FORECAST. MVFR CLOUDS WILL ERODE BY 15Z AT ALL
TERMINALS SAVE FOR ZZV WHERE IT WILL LINGER INTO THE 16-17Z TIME
FRAME. AFTER STRATOCU MIXES OUT LOOK FOR VFR WX THE BALANCE OF THE
FORECAST.
OUTLOOK...MONDAY NIGHT THROUGH FRIDAY...
NO WIDESPREAD IFR WEATHER PREDICTED.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...98
NEAR TERM...98
AVIATION...98
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1013 PM EST TUE FEB 21 2012
.UPDATE...
ISSUED AT 1011 PM EST TUE FEB 21 2012
MAIN FCST CONCERN OVERNIGHT IS SNOW ACCUMULATIONS OVER THE W.
WATER VAPOR IMAGERY SHOWS MID LEVEL LOW MOVING OVER WRN LAKE
SUPERIOR ATTM WITH ASSOCIATED MOIST...CYCLONIC FLOW SUPPORTING
-SN/-SHSN ACROSS NE MN INTO FAR NW WI AND W/NCNTRL UPPER MI. MORE
CONVECTIVE LOOKING -SHSN SPREADING ACROSS WRN UPPER MI PER KMQT
RADAR IMAGERY ARE JUST AHEAD OF RUC ANALYZED VORT MAX. PROBABLY SOME
DECENT SNOW RATES OCCURRING WITH THE 28+DBZ ECHOES...THOUGH SHORT
LIVED. FARTHER W...SNOW LOOKS LESS CONVECTIVE ON KDLH RADAR.
UPSTREAM...00Z KINL SOUNDING SHOWED DEEP MOISTURE TO 500MB.
HOWEVER...CAA AT THE LOWER LEVELS HAS BEEN MINIMAL TODAY AS 12Z AND
00Z 850MB TEMPS WERE -7C. THIS WILL PUT AIR MASS FLOWING OVER WRN
LAKE SUPERIOR AT THE MARGINAL THRESHOLD FOR LAKE ENHANCEMENT
OVERNIGHT. CONSIDERED POSSIBLE ADVY FOR ONTONAGON THRU KEWEENAW
OVERNIGHT INTO WED MORNING AS THIS WETTER SNOW (RATIO UNDER 20 TO 1)
FALLS UNDER LOWER ADVY CRITERIA (MAJORITY OF AREA AT LEAST 3 INCHES
IN 12HRS). GIVEN MARGINAL LAKE ENHANCEMENT CONDITIONS...OPTED TO
HOLD OFF ON ADVY ATTM. WOULD NOT BE SURPRISED TO SEE SOME OF THE
HIGHER TERRAIN AREAS AROUND THE PORCUPINE MTNS...BERGLAND...
ROCKLAND...TWIN LAKES AND PAINESDALE END UP AROUND 4 INCHES BY LATE
WED MORNING. HOWEVER...MAJORITY OF AREA SHOULD END UP IN THE 1-3 INCH
RANGE.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 400 PM EST TUE FEB 21 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER NRN
MN WITH A SHORTWAVE TROUGH EXTENDING INTO NW WI. 850-500 MB QVECTOR
CONV AND MID LEVEL FGEN ASSOCIATED WITH THE SHRTWV SUPPORTED A BAND
OF SNOW ACROSS CNTRL UPPER MI. SO...FAR ACCUMULATIONS HAVE BEEN
LIGHT...GENERALLY LESS THAN AN INCH. AT THE SFC...A 992 MB LOW WAS
LOCATED NEAR KINL WITH MOST OF THE SNOW AHEAD OF A TROUGH EXTENDING
TO THE SE THROUGH WRN UPPER MI INTO NE WI. ADDITIONAL SNOW OVER NE
MN WITH WRAP-AROUND MOISTURE NEAR THE MID LEVEL LOW WAS MOVING BACK
INTO NW WI.
RADAR TRENDS AND NAM/RUC FCST SUGGEST THAT THE INITIAL SNOWBAND WILL
MOVE OUT OF CNTRL UPPER MI INTO THE ERN CWA LATE THIS AFTERNOON AND
EVENING. THE SNOW AREA OVER MN IS ALSO EXPECTED TO SHIFT INTO WRN
UPPER MI THIS EVENING BRINGING POTENTIAL FOR ADDITIONAL LIGHT
ACCUMULATIONS OF AN INCH OR TWO. EVEN THOUGH THE STRONGER SYNOPTIC
FORCING IS FCST NEAR KIWD... THE COMBINATION OF CONVERGENT WRLY FLOW
AND 850 MB TEMPS DROPPING TO AROUND -8C WILL ALSO RESULT IN SOME
LAKE ENHANCED SNOW OVER NW UPPER MI WITH SNOWFALL AMOUNTS INTO THE 1
TO 3 INCH RANGE. AS THE WINDS VEER SLIGHTLY WED...THE LAKE ENHANCED
SNOW SHOULD ALSO MOVE INTO LOCATIONS NEAR LAKE SUPERIOR EAST OF
MUNISING. THE REMAINING SNOW OVER THE WEST WILL DIMINISH WED AS
HIGH PRESSURE AND DRIER AIR MOVE INTO THE AREA BEHIND THE DEPARTING
MID LEVEL LOW.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 400 PM EST TUE FEB 21 2012
THE 500MB LOW CURRENTLY OVER N MN THIS AFTERNOON WILL BE ALONG THE
ONTARIO/QUEBEC BORDER TO BEGIN THIS PERIOD. THE NEXT TROUGH SLIDING
IN FROM THE NW WILL BE BROAD...STRETCHING FROM W MANITOBA TO E LAKE
SUPERIOR/CENTRAL LAKE MI THURSDAY AFTERNOON. FCST MODELS BEGIN TO
DIVERGE EARLIER THAN NORMAL...THURSDAY AFTERNOON /DAY 2/.
THE 21/06Z NAM IS A QUICK OUTLIER...WITH A CLOSED LOW DEVELOPING
NEAR THE MACKINAC BRIDGE...BEFORE SHIFTING TO S QUEBEC FRIDAY
AFTERNOON. WHILE THE 21/06Z GFS HAS A SIMILAR TREND...IT IS APPROX 6
HOURS SLOWER. THE 21/09Z SREF TENDS TO FOLLOW A SOLUTION SIMILAR TO
THE GFS...WHILE THE 21/00Z CANADIAN IS AN AVERAGE BETWEEN THE
GFS/SREF AND THE MUCH SLOWER 21/00Z ECMWF /LOW OVER W ONTARIO WHILE
THE GFS HAS IT OVER THE S ONTARIO/QUEBEC BORDER/. THE ECMWF DOES NOT
PLACE THE LOW OVER THE S ONTARIO/QUEBEC BORDER UNTIL 12Z
SATURDAY...OR 18HRS BEHIND THE GFS. WILL PUSH THIS FORECAST CLOSER
TO A GFS SOLUTION THROUGH THE END OF THE WORK WEEK. THIS WILL RESULT
IN UPPER MI AND LAKE SUPERIOR STUCK BETWEEN THE FIRST SFC LOW
EXITING INTO QUEBEC AT 00Z THURSDAY...WITH THE STRONGER LOW
DEVELOPING OVER THE N PLAINS AND CENTRAL CANADA. A WEAK SFC TROUGH
WILL CONNECT THE TWO. THE MOST SIGNIFICANT CONTRAST THE MODELS CAN
BE SEEN OFF THE 00Z FRIDAY SFC MAP. THERE IS A CLUSTER OF MODELS
/GFS/NAM/SREF/ WITH THE LOW OVER CENTRAL TO N LOWER MI. BY CONTRAST
THE CANADIAN HAS IT ALONG THE LOWER MI/IA/OH BORDER...WITH THE ECMWF
ALONG THE CONFLUENCE OF THE OHIO AND MISSISSIPPI RIVERS. AS STATED
ABOVE...WILL PUSH THE FCST TO A MORE CENTRAL LOWER MI SOLUTION AT
00Z FRIDAY. THIS WILL KEEP THE BULK OF THE SYNOPTIC MOISTURE FALLING
JUST SOUTH OF THE CWA.
AFTER 18Z FRIDAY ALL OF THE SOLUTIONS COME INTO SOME BASIC AGREEMENT
OVER OUR CWA...WITH N TO NW WINDS AND 850MB TEMPS IN THE -8 TO -12C
RANGE. 850MB TEMPS OF -14 TO -16C SHOULD BE COMMON BY SUNDAY
AFTERNOON...BEFORE WAA ON MORE SW WINDS TAKE HOLD SATURDAY NIGHT.
STRONG SSW WINDS WILL LIKELY TAKE HOLD SUNDAY AFTERNOON INTO SUNDAY
NIGHT /DEPENDING ON THE TIMING OF THE NEXT LOW. THE ECMWF ENDS UP
BEING ROUGHLY 12 HOURS SLOWER THAN THE GFS WITH THIS NEXT SYSTEM
COMING OUT OF THE PLAINS. A STRONGER MORE NORTHERLY LOW OFF THE
ECMWF WOULD BRING 850MB TEMPS OF 2C...COMPARED TO THE WARMEST
READINGS OFF THE GFS OF -6C. AT 00Z TUESDAY THE SFC 983MB SFC LOW
OFF THE ECMWF IS OVER NE MN...WHILE AT THE SAME TIME THE
WEAKER/QUICKER GFS HAS A 1003MB LOW OVER FAR S QUEBEC. GIVEN THE
LOWER CONFIDENCE WITH THE FORECAST WILL NOT DIVE TO MUCH INTO THE
SPECIFICS...AND KEEP A CONSENSUS GOING FROM SATURDAY NIGHT ON. EVEN
WITH ALL THE DIFFERENCES...SUNDAY NIGHT LOOKED TO BE A GOOD
OPPORTUNITY TO INCLUDE LIKELY POPS OVER S CENTRAL UPPER MI.
OTHERWISE...WILL KEEP CHANCE OF LESS POPS GOING THROUGH MUCH OF THE
PERIOD WITH LOWER THAN NORMAL CONFIDENCE.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 656 PM EST TUE FEB 21 2012
MOISTURE/-SN WRAPPING AROUND MIDLEVEL LOW APPROACHING WRN LAKE
SUPERIOR WILL AFFECT KIWD/KCMX/KSAW TONIGHT INTO WED MORNING. KCMX
WILL BE IMPACTED MOST. AFTER BRIEF IMPROVEMENT IN THE LAST HR...
EXPECT CONDITIONS AT KCMX TO FALL BACK TO PREDOMINANTLY IFR THIS
EVENING UNDER UPSLOPING WESTERLY FLOW OFF LAKE SUPERIOR. AT
KIWD...MVFR CONDITIONS SHOULD PREVAIL WITH LESS LAKE INFLUENCES. AT
KSAW...DOWNSLOPING WIND COMPONENT WILL RESULT IN HIGHER MVFR CIGS
TONIGHT WITH -SN PROBABLY NOT CAUSING MUCH VIS RESTRICTION.
IMPROVEMENT EXPECT WED AS MIDLEVEL LOW DEPARTS...THOUGH MVFR
CONDITIONS WILL PROBABLY LINGER AT KIWD/KCMX.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 400 PM EST TUE FEB 21 2012
AS LOW PRESSURE SLIDES EASTWARD THROUGH NRN LAKE SUPERIOR AND
INTO QUEBEC BY WED AFTERNOON...WRLY WINDS WILL INCREASE TO 20 TO 30
KT TONIGHT INTO WED. WINDS WILL DIMINISH LATE WED INTO WED NIGHT AS
HIGH PRES BUILDS INTO THE UPPER GREAT LAKES. WINDS WILL THEN REMAIN
RELATIVELY LIGHT INTO UNTIL FRI WHEN NRLY WINDS OF 15 TO 25 KT ARE
POSSIBLE AS LOW PRESSURE MOVES TO THE SOUTH OF THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...ROLFSON
SHORT TERM...JLB
LONG TERM...KF
AVIATION...ROLFSON
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
656 PM EST TUE FEB 21 2012
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 400 PM EST TUE FEB 21 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER NRN
MN WITH A SHORTWAVE TROUGH EXTENDING INTO NW WI. 850-500 MB QVECTOR
CONV AND MID LEVEL FGEN ASSOCIATED WITH THE SHRTWV SUPPORTED A BAND
OF SNOW ACROSS CNTRL UPPER MI. SO...FAR ACCUMULATIONS HAVE BEEN
LIGHT...GENERALLY LESS THAN AN INCH. AT THE SFC...A 992 MB LOW WAS
LOCATED NEAR KINL WITH MOST OF THE SNOW AHEAD OF A TROUGH EXTENDING
TO THE SE THROUGH WRN UPPER MI INTO NE WI. ADDITIONAL SNOW OVER NE
MN WITH WRAP-AROUND MOISTURE NEAR THE MID LEVEL LOW WAS MOVING BACK
INTO NW WI.
RADAR TRENDS AND NAM/RUC FCST SUGGEST THAT THE INITIAL SNOWBAND WILL
MOVE OUT OF CNTRL UPPER MI INTO THE ERN CWA LATE THIS AFTERNOON AND
EVENING. THE SNOW AREA OVER MN IS ALSO EXPECTED TO SHIFT INTO WRN
UPPER MI THIS EVENING BRINGING POTENTIAL FOR ADDITIONAL LIGHT
ACCUMULATIONS OF AN INCH OR TWO. EVEN THOUGH THE STRONGER SYNOPTIC
FORCING IS FCST NEAR KIWD... THE COMBINATION OF CONVERGENT WRLY FLOW
AND 850 MB TEMPS DROPPING TO AROUND -8C WILL ALSO RESULT IN SOME
LAKE ENHANCED SNOW OVER NW UPPER MI WITH SNOWFALL AMOUNTS INTO THE 1
TO 3 INCH RANGE. AS THE WINDS VEER SLIGHTLY WED...THE LAKE ENHANCED
SNOW SHOULD ALSO MOVE INTO LOCATIONS NEAR LAKE SUPERIOR EAST OF
MUNISING. THE REMAINING SNOW OVER THE WEST WILL DIMINISH WED AS
HIGH PRESSURE AND DRIER AIR MOVE INTO THE AREA BEHIND THE DEPARTING
MID LEVEL LOW.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 400 PM EST TUE FEB 21 2012
THE 500MB LOW CURRENTLY OVER N MN THIS AFTERNOON WILL BE ALONG THE
ONTARIO/QUEBEC BORDER TO BEGIN THIS PERIOD. THE NEXT TROUGH SLIDING
IN FROM THE NW WILL BE BROAD...STRETCHING FROM W MANITOBA TO E LAKE
SUPERIOR/CENTRAL LAKE MI THURSDAY AFTERNOON. FCST MODELS BEGIN TO
DIVERGE EARLIER THAN NORMAL...THURSDAY AFTERNOON /DAY 2/.
THE 21/06Z NAM IS A QUICK OUTLIER...WITH A CLOSED LOW DEVELOPING
NEAR THE MACKINAC BRIDGE...BEFORE SHIFTING TO S QUEBEC FRIDAY
AFTERNOON. WHILE THE 21/06Z GFS HAS A SIMILAR TREND...IT IS APPROX 6
HOURS SLOWER. THE 21/09Z SREF TENDS TO FOLLOW A SOLUTION SIMILAR TO
THE GFS...WHILE THE 21/00Z CANADIAN IS AN AVERAGE BETWEEN THE
GFS/SREF AND THE MUCH SLOWER 21/00Z ECMWF /LOW OVER W ONTARIO WHILE
THE GFS HAS IT OVER THE S ONTARIO/QUEBEC BORDER/. THE ECMWF DOES NOT
PLACE THE LOW OVER THE S ONTARIO/QUEBEC BORDER UNTIL 12Z
SATURDAY...OR 18HRS BEHIND THE GFS. WILL PUSH THIS FORECAST CLOSER
TO A GFS SOLUTION THROUGH THE END OF THE WORK WEEK. THIS WILL RESULT
IN UPPER MI AND LAKE SUPERIOR STUCK BETWEEN THE FIRST SFC LOW
EXITING INTO QUEBEC AT 00Z THURSDAY...WITH THE STRONGER LOW
DEVELOPING OVER THE N PLAINS AND CENTRAL CANADA. A WEAK SFC TROUGH
WILL CONNECT THE TWO. THE MOST SIGNIFICANT CONTRAST THE MODELS CAN
BE SEEN OFF THE 00Z FRIDAY SFC MAP. THERE IS A CLUSTER OF MODELS
/GFS/NAM/SREF/ WITH THE LOW OVER CENTRAL TO N LOWER MI. BY CONTRAST
THE CANADIAN HAS IT ALONG THE LOWER MI/IA/OH BORDER...WITH THE ECMWF
ALONG THE CONFLUENCE OF THE OHIO AND MISSISSIPPI RIVERS. AS STATED
ABOVE...WILL PUSH THE FCST TO A MORE CENTRAL LOWER MI SOLUTION AT
00Z FRIDAY. THIS WILL KEEP THE BULK OF THE SYNOPTIC MOISTURE FALLING
JUST SOUTH OF THE CWA.
AFTER 18Z FRIDAY ALL OF THE SOLUTIONS COME INTO SOME BASIC AGREEMENT
OVER OUR CWA...WITH N TO NW WINDS AND 850MB TEMPS IN THE -8 TO -12C
RANGE. 850MB TEMPS OF -14 TO -16C SHOULD BE COMMON BY SUNDAY
AFTERNOON...BEFORE WAA ON MORE SW WINDS TAKE HOLD SATURDAY NIGHT.
STRONG SSW WINDS WILL LIKELY TAKE HOLD SUNDAY AFTERNOON INTO SUNDAY
NIGHT /DEPENDING ON THE TIMING OF THE NEXT LOW. THE ECMWF ENDS UP
BEING ROUGHLY 12 HOURS SLOWER THAN THE GFS WITH THIS NEXT SYSTEM
COMING OUT OF THE PLAINS. A STRONGER MORE NORTHERLY LOW OFF THE
ECMWF WOULD BRING 850MB TEMPS OF 2C...COMPARED TO THE WARMEST
READINGS OFF THE GFS OF -6C. AT 00Z TUESDAY THE SFC 983MB SFC LOW
OFF THE ECMWF IS OVER NE MN...WHILE AT THE SAME TIME THE
WEAKER/QUICKER GFS HAS A 1003MB LOW OVER FAR S QUEBEC. GIVEN THE
LOWER CONFIDENCE WITH THE FORECAST WILL NOT DIVE TO MUCH INTO THE
SPECIFICS...AND KEEP A CONSENSUS GOING FROM SATURDAY NIGHT ON. EVEN
WITH ALL THE DIFFERENCES...SUNDAY NIGHT LOOKED TO BE A GOOD
OPPORTUNITY TO INCLUDE LIKELY POPS OVER S CENTRAL UPPER MI.
OTHERWISE...WILL KEEP CHANCE OF LESS POPS GOING THROUGH MUCH OF THE
PERIOD WITH LOWER THAN NORMAL CONFIDENCE.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 656 PM EST TUE FEB 21 2012
MOISTURE/-SN WRAPPING AROUND MIDLEVEL LOW APPROACHING WRN LAKE
SUPERIOR WILL AFFECT KIWD/KCMX/KSAW TONIGHT INTO WED MORNING. KCMX
WILL BE IMPACTED MOST. AFTER BRIEF IMPROVEMENT IN THE LAST HR...
EXPECT CONDITIONS AT KCMX TO FALL BACK TO PREDOMINANTLY IFR THIS
EVENING UNDER UPSLOPING WESTERLY FLOW OFF LAKE SUPERIOR. AT
KIWD...MVFR CONDITIONS SHOULD PREVAIL WITH LESS LAKE INFLUENCES. AT
KSAW...DOWNSLOPING WIND COMPONENT WILL RESULT IN HIGHER MVFR CIGS
TONIGHT WITH -SN PROBABLY NOT CAUSING MUCH VIS RESTRICTION.
IMPROVEMENT EXPECT WED AS MIDLEVEL LOW DEPARTS...THOUGH MVFR
CONDITIONS WILL PROBABLY LINGER AT KIWD/KCMX.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 400 PM EST TUE FEB 21 2012
AS LOW PRESSURE SLIDES EASTWARD THROUGH NRN LAKE SUPERIOR AND
INTO QUEBEC BY WED AFTERNOON...WRLY WINDS WILL INCREASE TO 20 TO 30
KT TONIGHT INTO WED. WINDS WILL DIMINISH LATE WED INTO WED NIGHT AS
HIGH PRES BUILDS INTO THE UPPER GREAT LAKES. WINDS WILL THEN REMAIN
RELATIVELY LIGHT INTO UNTIL FRI WHEN NRLY WINDS OF 15 TO 25 KT ARE
POSSIBLE AS LOW PRESSURE MOVES TO THE SOUTH OF THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...ROLFSON
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
346 PM EST MON FEB 20 2012
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 346 PM EST MON FEB 20 2012
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR RDG OVER THE
GREAT LKS BTWN TROF IN SE CAN AND ANOTHER IN THE PLAINS. AT THE
SFC...UPR MI LIES UNDER A SHARPENING PRES GRADIENT BTWN SFC HI PRES
OVER OH AND LOWER PRES IN THE PLAINS UNDER THE TROF. ALTHOUGH HI
CLDS ARE STREAMING OVHD IN THE SW FLOW ALF...12Z RAOBS TO THE S AT
GRB/MPX/AND QUAD CITIES IA SHOW DRY LO/MID LVLS. SINCE THE SUN IS
JUST FILTERED A BIT BY THESE HI CLDS...TEMPS HAVE REBOUNDED TO WELL
ABV NORMAL LVLS AGAIN AND WELL INTO THE 30S AT MOST SPOTS EARLY THIS
AFTN. ALTHOUGH THERE A LARGER SCALE TROF IN THE PLAINS...SEVERAL OUT
OF PHASE SHRTWVS ARE PRESENT WITHIN THE BROADER AREA OF LOWER HGTS.
THE STRONGEST OF THESE IS OVER THE SCNTRL PLAINS...WITH ANOTHER OVER
SASKATCHEWAN.
MAIN FCST CONCERNS THRU TUE REVOLVE ARND PCPN CHCS TNGT/TUE RELATED
TO EWD PROGRESSION OF PLAINS TROF AND EMBEDDED SHRTWVS. RECENT MODEL
RUNS ARE IN FAIRLY GOOD AGREEMENT SHOWING SHRTWVS/ASSOCIATED SFC LO
CENTERS REMAINING OUT OF PHASE THRU TUE...WHICH WILL LIMIT PCPN
TOTALS OVER THE CWA. IN GENERAL...FOLLOWED THE GFS FOR FCST DETAILS
AT THIS MODEL SHOWS MORE PERSISTENT LLVL DRY AIR WITH MORE MSTR TIED
TO THE STRONGER SRN DISTURBANCE FCST TO TRACK THRU THE LOWER LKS.
TNGT...SHRTWV OVER SASKATCHEWAN IS FCST TO DIG TOWARD MN BY 12Z
WHILE SRN DISTURBANCE MOVES INTO ILLINOIS. PREFERRED GFS SHOWS MORE
IMPRESSIVE QVECTOR CNVGC TENDING TO REMAIN TO THE W AND S OF THE FA.
SINCE SLOWLY BACKING WINDS FM THE SSW TOWARD THE SE WL MAINTAIN LLVL
DRY AIR FEED...PREFERRED GFS MODEL INDICATES PERSISTENT DRY WEDGE IN
THE LLVLS PERSISTING THRU 12Z OVER UPR MI. SO EXCEPT FOR WRN LK
SUP...WHICH WL BE CLOSEST TO INCOMING DYNAMICS ASSOCIATED WITH THE
NRN DISTURBANCE...TENDED TO CUT POPS OVER THE CWA. DESPITE LINGERING
DRY AIR IN THE LLVLS...A STRONGER SW FLOW AND THICKENING HI CLDS WL
PREVENT TEMPS FM FALLING AS SHARPLY AS THE LAST FEW NIGHTS.
TUE...WHILE SRN SHRTWV MOVES ENEWD WELL S OF THE FA...THE NRN
DISTURBANCE IS FCST TO DRIFT EWD INTO THE UPR LKS. WITH INCRSG DPVA/
LLVL MOISTENING/LARGE SCALE QVECTOR CNVGC/SOME UPR DVGC...EXPECT
INCRSG POPS TOWARD CATEGORICAL IN THE AFTN. HOWEVER...SINCE MOST OF
THE DYNAMICS WL BE SPENT SATURATING THE INITIALLY DRY LO/MID LVLS...
PCPN AMNTS WL BE RELATIVELY LGT AND UNDER 0.25 INCH. ALTHOUGH MAX
TEMPS WL TOP OUT OVER 32 ALMOST EVERYWHERE...DYNAMIC/WBLB COOLING
SHOULD KEEP PCPN IN THE FORM OF SN PER GFS FCST SNDGS AND H100-85
THKNS/WBZ HGT BLO CRITICAL LVLS.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 346 PM EST MON FEB 20 2012
THE SLOW MOVING 500MB LOW OVER CENTRAL SASKATCHEWAN THIS AFTERNOON
WILL BE OVER N MN/W LAKE SUPERIOR AT 00Z WEDNESDAY...SETTING US UP
FOR AN ACTIVE PERIOD OF LIGHT SNOW SHOWERS.
EXPECT THE 500MB LOW TO BE DIRECTLY OVER UPPER MI AT 06Z
WEDNESDAY...WITH THE 20/06Z GFS SHOWING MORE OF AN OPEN WAVE INSTEAD
OF A CLOSED LOW. THE RESULT IS A MORE PROGRESSIVE /THAN THE
CONSENSUS AND ITS 20/00Z RUN/. EVEN AT THE SFC THE LOW IS QUITE A
BIT FARTHER TO THE SOUTH...BUT WITHIN REASON. ANOTHER DISCREPANCY
WOULD BE FROM THE 20/06Z NAM...WITH IS ON THE SLOW SIDE NEARLY RIGHT
OFF THE BAT. THE DIFFERENCE BETWEEN THE PLACEMENT OF THE FASTER GFS
AND SLOWER NAM IS ROUGHLY 240MI. EXPECT THE ELONGATED TO DOUBLE
BARREL SFC LOW STRETCHING FROM N MN TO SE IA AT 12Z TUESDAY TO
DEEPEN ACROSS E LAKE SUPERIOR TUESDAY NIGHT...BEFORE SLIDING ALMOST
DIRECTLY E INTO S QUEBEC LATE TUESDAY NIGHT INTO WEDNESDAY. WHILE A
SFC TROUGH WILL LINGER BEHIND THE EXITING LOW...IT WILL BE OF SHORT
DURATION...AS A SFC RIDGE QUICKLY BUILDS IN WEDNESDAY AFTERNOON
AHEAD OF THE NEXT LOW. ANOTHER HINDRANCE TO HEAVY SNOW WILL BE THE
RELATIVELY MILD 850MB TEMPS NEAR -8C...AND PREDOMINANT WNW WINDS
BEHIND THE SFC LOW. WHILE LAKE ENHANCEMENT WILL BE POSSIBLE AS THE
LOW MOVES OVERHEAD...SHIFTING WINDS WILL DETER SIGNIFICANT AMOUNTS.
THE BEST CHANCE OF RECEIVING 2-5 INCHES WOULD BE FROM IWD TO
CMX.
THE NEXT 500MB FEATURE OF IMPORTANCE WILL BE IN THE FORM OF A S
CENTRAL CANADIAN TROUGH WEDNESDAY NIGHT...SLIDING ACROSS THE UPPER
GREAT LAKES THURSDAY AFTERNOON. THE CONSENSUS IS TO HAVE THIS TROUGH
DEEPEN INTO A LOW UPPER MI FRIDAY...BEFORE MOVING INTO S QUEBEC
FRIDAY NIGHT. WHILE THE ORIGINS OF THE SFC LOW...OVER SASKATCHEWAN
WEDNESDAY AFTERNOON WOULD INDICATE ANOTHER LOW WITH LITTLE IN THE
WAY OF MOISTURE TO WORK WITH...ITS PROGRESSION WILL ALLOW THE GULF
TO OPEN UP. EXPECT THE SFC LOW TO RESIDE BETWEEN CENTRAL WI/CENTRAL
LOWER MI/CENTRAL UPPER MI AT 18Z THURSDAY /WITH THE ECMWF FARTHER
SOUTH THAN THIS/...AND A COLD FRONT DRAGGING ACROSS IL/MO/AND INTO
NE TX. THE SFC LOW SHOULD DEEPEN AS IT SLIDES EAST OF OUR
AREA...THURSDAY NIGHT NEAR THE LOWER GREAT LAKES...AND FRIDAY
AFTERNOON/EVENING OVER S QUEBEC. AS THE SYSTEM DEEPENS AND TAPS INTO
ADDITIONAL MOISTURE OFF THE ATLANTIC IT SHOULD WRAP IN STEADY N
WINDS SLOWLY BECOMING NW...AND PLENTY OF COLD AIR TO OUR REGION
FRIDAY AFTERNOON THROUGH SATURDAY NIGHT. 850MB TEMPS AT THIS POINT
THE PRESSURE GRADIENT BECOMES FAIRLY WEEK WITH A SFC RIDGE NEARLY
OVERHEAD.
PRECIPITATION TYPE MAY BE A CONCERN FOR THIS SYSTEM OVER THE SE
CORNER OF THE CWA RIGHT ALONG LAKE MICHIGAN. 850MB TEMPS OF THE
20/06Z GFS ARE AROUND -4C...WITH THE MNM SOUNDING SHOWING
INDICATIONS OF RA FROM MID MORNING THROUGH THE REMAINDER OF THE
DAYTIME HOURS THURSDAY. THE EVEN WARMER/MORE WRAPPED UP 20/00Z
CANADIAN WOULD HAVE 850MB TEMPS AROUND -2C OVER THE ENTIRE CWA
AROUND 12Z THURSDAY...LINGERING EAST AS THE LOW EXITS EARLY THURSDAY
EVENING. WILL NOT CONCENTRATE TOO MUCH ON THIS...AS THERE ARE LARGER
DISCREPANCIES...WITH THE NAM AND ECMWF NOT TOO ENTHUSED ABOUT THE
NORTHERN EXTENT OF THE SYSTEM...WITH THE BULK OF THE MOISTURE
REMAINING OVER IL/IN/OH. BOTH THE GFS AND ECMWF SHOW GOOD RUN TO RUN
CONSISTENCY...WITH A BLEND LOOKING REASONABLE AT THIS TIME. THE 12Z
RUNS OF THE GFS AND ECMWF KEPT WITH A MORE SOUTHERLY SOLUTION FOR
THIS SYSTEM...CLOSER TO THE 00Z RUN OF THE ECMWF. THIS TREND WOULD
CONTINUE TO LIMIT THE MENTION OF RAIN NEAR LAKE MICHIGAN. NO MATTER
WHICH SOLUTION OR GROUP OF SOLUTIONS IS PREFERRED...850MB TEMPS
SHOULD FALL BETWEEN -12 AND -16C FROM FRIDAY NIGHT ON...WITH
FAVORABLE WINDS OFF LAKE SUPERIOR PRODUCING LIGHT TO MODERATE SNOW
SHOWERS.
BEYOND FRIDAY NIGHT THE 20/06Z GFS AND 20/00Z ECMWF BECOME OUT OF
PHASE. THIS IS BEST INDICATED BY THE LATE SATURDAY AFTERNOON/SUNDAY
NIGHT TRENDS AT 500MB OVER THE GREAT LAKES...WITH THE ECMWF
INDICATING A RIDGE AND THE GFS A TROUGH. THIS IS MAINLY DUE TO THE
HANDLING OF THE LOW EJECTING E SATURDAY. THE ECMWF IS ON THE QUICKER
SIDE...WHILE THE LAST 2 GFS RUNS CONTINUE TO DEEPEN THE LOW AS IT
SHIFTS INTO FAR EASTERN CANADA. AS A RESULT...WILL NOT TRY TO PIN
POINT SPECIFICS BEYOND SATURDAY NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1220 PM EST MON FEB 20 2012
ALTHOUGH THERE WL BE AN INCRS IN MID/HI CLDS AS LO PRES TROF IN THE
PLAINS MIGRATES SLOWLY TO THE E...EXPECT VFR CONDITIONS TO PREVAIL
THRU TNGT WITH LLVL SSE FLOW MAINTAINING DRY AIR BLO 10K FT. AS THE
PRES GRADIENT TIGHTENS OVER UPR MI...MAINTAINED FCST LLWS AT ALL 3
SITES FOR AT LEAST A TIME TNGT BEFORE GRADIENT WEAKENS LATE. AS THE
LO PRES TROF TO THE W MOVES CLOSER ON TUE AND SOME -SN OVERSPREADS
THE AREA...MVFR CONDITIONS WL PREDOMINATE BY LATE MRNG.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 346 PM EST MON FEB 20 2012
WITH AN UNSEASONABLY WEAK PRES GRADIENT FORECAST THIS WEEK...EXPECT
WINDS NO HIER THAN 25 KTS. NO GALES ARE FORECAST IN THE NEAR FUTURE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1224 AM EST MON FEB 20 2012
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 347 PM EST SUN FEB 19 2012
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW ALF OVER
THE UPR LKS BTWN TROF IN QUEBEC AND UPR RDG MOVING E THRU THE
PLAINS. SFC HI PRES RDG IS ORIENTED FM LOWER MI INTO SRN WI...
BRINGING QUIET DAY TO THE CWA. EXCEPT FOR LINGERING SC E OF ERY
TOWARD BACK EDGE OF SLOWLY DEPARTING H925 THERMAL TROF/A BIT MORE
LLVL MSTR SHOWN ON THE 12Z APX RAOB...SKIES ARE GENERALLY SUNNY OVER
THE CWA AS 12Z GRB/MPX/INL RAOBS DEPICT A DRY AIRMASS WITH PWAT 0.15
TO 0.20 INCH. THERE IS A SHRTWV DROPPING ESEWD OVER THE UPR LKS...
BUT ONLY SOME HI CLDS MARK THE PRESENCE OF THIS FEATURE WITH DRY LO/
MID LVLS PRESENT. ALTHOUGH MIN TEMPS THIS MRNG FELL BLO ZERO AT A
NUMBER OF INTERIOR LOCATIONS...THE BRIGHT SUNSHINE HAS HELPED THE
MERCURY RECOVER TO WELL ABV NORMAL LEVELS THIS AFTN. FARTHER TO THE
W...THERE IS A TROF IN THE ROCKIES. QUITE A BIT OF HI CLDS ARE
STREAMING NEWD THRU THE PLAINS TOWARD MN IN THE SW FLOW ALF AHEAD OF
THIS FEATURE.
MAIN FCST CONCERNS IN THE SHORT TERM ARE TEMPS WITH HI PRES RDG
EXPECTED TO DOMINATE.
TNGT...UPR RDG IS FCST TO BUILD OVHD TNGT WITH DRY AIRMASS STILL
DOMINATING. ANY LINGERING LO CLDS OVER THE FAR ERN CWA SHOULD BE
GONE BY FCST ISSUANCE WITH WLY FLOW/WARMING AND DRYING AT H925.
EXPECT THE LOWEST MIN TEMPS AOB THE LO END OF GUIDANCE OVER THE
INTERIOR E AND SCNTRL UNDER WEAKER PRES GRADIENT/LIGHTER SW FLOW
ARND HI PRES CENTERED OVER LOWER MI. ADDED SOME PATCHY FOG IN THESE
AREAS OVER THE E WHERE SFC DEWPTS REMAIN FAIRLY HI AOA 20. A BIT
STRONGER SW FLOW OVER THE NW HALF AND THE ARRIVAL OF SOME HI CLDS
AHEAD OF THE SLOWLY PROGRESSIVE ROCKIES TROF WL LIMIT THE DIURNAL
FALL OF TEMP IN THAT AREA A BIT.
MON...EXPECT INCRSG SLY FLOW OVER UPR MI BTWN DEPARTING UPR RDG/SFC
HI TO THE E AND APRCHG UPR TROF THRU THE PLAINS IN PROGRESSIVE
PATTERN ALF. ALTHOUGH THERE WL BE QUITE A BIT OF HI CLD UNDER THE SW
FLOW ALF...THE LO/MID LVLS WL REMAIN QUITE DRY. H85 TEMPS ARE FCST
TO RISE CLOSE TO 0C OVER THE W BY LATE IN THE DAY...SO EXPECT A
HEALTHY DIURNAL TEMP RECOVERY DESPITE THE HI CLD COVER. TEMPS ARE
LIKELY TO BE HIEST IN THE DOWNSLOPE AREAS NEAR LK SUP FM IWD-COPPER
HARBOR...BARAGA AND MQT. TEMPS ARE LIKELY TO REACH 40 OR BETTER IN
THESE LOCATIONS. AREAS NEAR THE ICE ON THE BAY OF GREEN BAY WL BE
COOLEST.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 347 PM EST SUN FEB 19 2012
SPLIT FLOW TO START THE PERIOD WITH STRONGER JET STREAM REMAINING IN
THE SOUTHERN BRANCH. MODELS ARE IN PRETTY GOOD AGREEMENT WITH
PLACEMENT OF THE TWO SHORTWAVE TROUGHS OVR CENTRAL CONUS INTO SOUTH
CENTRAL CANADA ON MONDAY EVENING. UPR LEVEL WAVES STILL LOOK TO
REMAIN SEPARATE INTO TUESDAY BUT H85 LOWS DO TRY TO MERGE TOGETHER
OVR NW ONTARIO AND LK SUPERIOR REGION BY TUESDAY AFTN. RESULT IS A
SW FLOW OF INCREASING MOISTURE INTO UPR MI LATER MONDAY NIGHT INTO
TUESDAY. MORE ABUNDANT MOISTURE/HIGHER PWATS STAY TIED TO SOUTHERN
STREAM UPR SYSTEM TRACKING ACROSS NORTHERN OHIO VALLEY INTO CNTRL
GREAT LAKES. EXPECT SWATH OF SNOW FORCED BY DIVERGENCE FM UPR JET
AND MID LEVEL FRONTOGENEIS TO LIFT INTO WESTERN UPR MI AFTER
MIDNIGHT MONDAY NIGHT THROUGH MID MORNING ON TUESDAY. SNOW SHOULD
FADE AWAY THROUGH THE DAY WHILE MOVING EAST AS MAIN MOISTURE STREAMS
BEGIN TO SPLIT AROUND UPR MI. BEST CHANCE FOR ACCUMULATING SNOW
WOULD BE IN THE FAR WESTERN CWA AROUND KIWD EARLY ON TUESDAY. DID
OPT FOR MENTION OF RAIN ALONG IMMEDIATE LK MICHIGAN SHORE LATER ON
TUESDAY WITH ONSHORE WINDS.
KIND OF A TRICKY FCST BEYOND TUESDAY AT THIS POINT...ESPECIALLY
THROUGH THURSDAY. MAIN ITEM CASTING UNCERTAINTY IS GENERAL TROUGHING
STAYING PUT FM SCNTRL CANADA INTO UPR LAKES. INITALLY ON TUESDAY
NIGHT...PRIMARY FOCUS FOR WIDESPREAD/STEADY PCPN SHOULD BE NORTH AND
NORTHEAST OF UPR MI OVER ONTARIO/QUEBEC IN VCNTY OF SFC-H85 LOW.
H85-H7 MOISTURE DOES LINGER THOUGH...ESPECIALLY OVR LK SUPERIOR.
MOISTURE COMBINED WITH WESTERLY FLOW AND H85 TEMPS DOWN TO AROUND
-10C COULD LEAD TO LGT SNOW SHOWERS ACROSS KEWEENAW. MINIMAL CHANGE
INTO WEDNESDAY...AS WEST-NORTHWEST LOW-LEVEL WINDS PERSIST OVER THE
AREA AS SFC LOW LIFTS INTO QUEBEC. UPR LAKES IS WITHIN BASE OF LARGER
TROUGH...SO THERE COULD BE SOME SHORTWAVES SLIDING BY IN THE FLOW
THAT ARE NOT DEPICTED IN THE MODELS RIGHT NOW. OVERALL...SEEMS LIKE
SOME SMALL CHANCE POPS ARE JUSTIFIED...BUT NOTHING MORE AT THIS
POINT.
FOR THE EXTENDED...YESTERDAY IT LOOKED LIKE ONCE SFC-H85 LOWS WOULD
TRACK INTO QUEBEC IT WOULD USHER IN NW FLOW LK EFFECT BY THURSDAY
INTO FRIDAY. PATTERN LOOKING NOT AS CLEAR CUT NOW. MODELS...
ESPECIALLY LATEST VERSIONS OF GFS AND CANADIAN...POINT TO STRONGER
COMPACT LOW PRESSURE SYSTEM RIDING SOUTHERN EDGE OF THE TROUGH FM
NORTHERN ROCKIES ACROSS THE NORTHERN PLAINS WEDNESDAY AND WEDNESDAY
NIGHT AND INTO UPR GREAT LAKES THURSDAY/THURSDAY NIGHT. EARLIER THE
GFS WAS FARTHEST NORTH WITH THE LOW/QPF THAN OTHER MODELS...BUT
LATEST CANADIAN NOW TAKES THAT TITLE. ECMWF IS FARTHER SOUTH AND
MORE SHEARED OUT WITH THE DISTURBANCE. BLEND OF MODELS AND THE GFS
ENSEMBLE WOULD SUGGEST FAR SOUTH CWA SEES THE BEST CHANCE OF SNOW
LATER WEDNESDAY NIGHT INTO THURSDAY. DETAILS ARE FAR FM SET THOUGH.
GIVEN UNCERTAINTY WILL STEER AWAY FM LK EFFECT POP IDEA FOR THURSDAY
AND OPEN UP MOST OF CWA FOR LOW CHANCE POPS. MOST MODELS INDICATE
LOW-LEVEL WINDS OVR NOTHERN CWA WOULD BE FM THE NORTH OR NORTHEAST
THURSDAY/THURSDAY NIGHT WITH AT LEAST SUFFICIENT LOW-LEVEL MOISTURE.
INSTABILITY WOULD BE MARGINAL WITH DELTA T/S ONLY UP TO 13C. IF THE
LOW PRESSURE DOES TRACK FARTHER NORTH...THEN THERE WOULD BE MORE
POTENTIAL OF LAKE ENHANCEMENT.
EVENTUALLY...EXPECT NW FLOW LK EFFECT TO DEVELOP OVR THE AREA IN
WAKE OF THIS SYSTEM LATER THURSDAY NIGHT INTO FRIDAY AND ON INTO
SATURDAY AS WELL. H85-H7 DEEPER MOISTURE ALONG WITH SUFFICIENT
OVER-WATER INSTABILITY MAY SUPPORT SOME MODERATE ACCUMS IN THE
THURSDAY NIGHT/FRIDAY TIME FRAME. COLDEST DAYS OVR THE CWA SHOULD
BE FRIDAY AND SATURDAY...WITH HIGHS STAYING IN THE TEENS FOR SOME OF
THE AREA. SUFFICIENTLY COLD AIR /H85 TEMPS BLO -15C/ PERSISTS INTO
SATURDAY THOUGH DECREASING SUB H85 MOISTURE AND LOWERING INVERSIONS
WITH ARRIVAL OF SFC-H85 RIDGE SHOULD BEGIN TO PUT DENT IN THE LK
EFFECT. UNCERTAINTY BACK INTO FCST BY SUNDAY AS GFS AND PREVIOUS
ECMWF WERE OUT OF PHASE WITH EACH OTHER. LATEST ECMWF IS MORE IN
LINE WITH GFS IDEA THOUGH SUGGESTING SYSTEM SNOW COULD RETURN TO UPR
LAKES LATE NEXT WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1222 AM EST MON FEB 20 2012
VFR CONDITIONS WILL CONTINUE TO PREVAIL THRU THIS FCST PERIOD AT
KIWD/KCMX/KSAW AS DRY AIR LINGERS DESPITE HIGH PRES SHIFTING E TO
THE LOWER GREAT LAKES. A STRONGER S WIND WILL DEVELOP TODAY UNDER
SHARPENING PRES GRADIENT BTWN THE DEPARTING HIGH PRES AND LOW PRES
APPROACHING FROM THE PLAINS. MAY SEE LLWS DEVELOP THIS EVENING
DEPENDING UPON DEGREE OF DECOUPLING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 347 PM EST SUN FEB 19 2012
WITH AN UNSEASONABLY WEAK PRES GRADIENT FORECAST INTO TUE...EXPECT
WINDS NO HIER THAN 25 KTS. A STRONGER W WIND TO 30 KTS IS POSSIBLE
TUE NIGHT AND WED ON THE SOUTHERN FLANK OF LO PRES CROSSING ONTARIO.
THERE MAY BE SOME GALE FORCE GUSTS OVER PORTIONS OF NCENTRAL AND
EASTERN LK SUP. MAINLY NORTH TO NORTHWEST WINDS LESS THAN 30 KTS
EXPECTED LATE THIS WEEK AS COLDER AIR RETURNS TO THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLA
AVIATION...ROLFSON
MARINE...KC/JLA
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
429 AM CST MON FEB 20 2012
.DISCUSSION...
100% POPS IN THE FORECAST ACROSS THE ENTIRE AREA WITHIN THE NEXT
24 HOURS WITH THE TROUGH TRANSVERSING THE ROCKIES EARLY THIS
MORNING. NOT THE SIMPLEST OF SNOW FORECASTS TODAY AND TONIGHT. THE
SLOWER TREND CONTINUES AND SEEMS WE PUSH BACK THE PRECIP WITH
EVERY FORECAST ISSUANCE...TONIGHT WAS NO DIFFERENT. TO COME UP
WITH THE CURRENT TIMING...BLENDED THE PREVIOUS DAY-SHIFT FORECAST
WITH THE 03Z SREF AND DID SOME SMOOTHING FROM THERE. THIS AGREES
WELL WITH THE SLOWER NCEP WRF-ARW/NMM GUIDANCE WHICH DOESNT BRING
PRECIP IN UNTIL AFTER 20Z. IT MIGHT NOT EVEN START WITH RAIN/SNOW
IN THE METRO UNTIL AFTER 6 PM THIS EVENING.
THE GUIDANCE HAS CONSISTENTLY BROUGHT A COUPLE TENTHS OR MORE OF
LIQUID TO THE FORECAST AREA...BUT THE BIG QUESTION HAS BEEN THE
WARM LAYER AND MIXED P-TYPE THIS AFTERNOON AND EARLY EVENING. I
WOULD SAY THE BIGGEST CHANGE TO THE NAM/GFS TONIGHT HAS BEEN THE
RAPID DYNAMIC COLUMN COOLING THIS AFTERNOON AND EVENING FROM WEST
TO EAST. EVEN WITH THE PV ANOMALY AND STRONGEST 500MB HEIGHT
FALLS OVER NORTHERN MISSOURI...THE COL/DEFORMATION AREA BETWEEN
THE NORTHERN AND SOUTHERN STREAM WAVES SUGGEST THE POTENTIAL FOR
A BRIEF WINDOW OF INTENSE SNOW BEFORE DRYING IN THE 600-700MB
LAYER MOVES IN BETWEEN 03-09Z...AGAIN FROM W/SW TO E/NE. WE`RE ON
THE EDGE OF THE BEST UPPER DIVERGENCE WITH THE LEFT EXIT REGION OF
THE UPPER JET AS WELL.
REMOVED THE SLEET FROM THE FORECAST EVEN WITH THE WARM WEDGE
BUILDING IN ON THE BACK OF A STRONG 850MB JET TODAY. JUST THINK
WHEN WE`RE WARM ALOFT WE`LL BE WARM AT THE SURFACE AS WELL AND GET
RAIN OUT OF IT. THE COLUMN COOLS TOP DOWN AND COULD BE AIDED
SLIGHTLY BY HEAVIER PRECIP FALLING THROUGH THE COLUMN...EVEN
THOUGH 1000-850MB WET BULB ISN`T COLD BY ANY MEANS. AGAIN...THE
NAM AND GFS SHOW THIS HAPPENING PRETTY FAST THIS AFTERNOON AND
EVENING. THERE WAS SOME CONCERN THIS MORNING WITH NEGATIVE EPV AND
STRONG FGEN WITH THE BAND THAT WE COULD GET A QUICK SNOW BURST AND
A COUPLE HOUR PERIOD WHEN SNOW RATES ARE NEAR OR ABOVE 1"/HR. THIS
MIGHT BE MORE OF A CONCERN IN THE DAKOTAS AND WEST CENTRAL MN. IN
FACT...SOME NWS OFFICES TO OUR WEST TOSSED AROUND THE POSSIBILITY
OF A WINTER STORM WARNING. NOT ENOUGH CONFIDENCE AT THIS POINT.
HOWEVER...WE DECIDED TO GO WITH AN ADVISORY TO MATCH WHAT OFFICES
TO OUR WEST DID. WE`VE GOT AROUND 3 INCHES IN WEST CENTRAL MN...SO
IT WAS CLOSE ENOUGH TO WHAT WE LIKE TO SEE FOR AN ADVISORY EVENT.
THERE MIGHT BE A FAIRLY DRAMATIC CUTOFF IN SNOW AMOUNTS FROM WEST
CENTRAL MN TO SOUTHWEST MN...GIVEN THE WARMER TEMPERATURES FURTHER
SOUTH. AT ANY RATE...HAVE A LOT OF THE AREA WITH AROUND 2 INCHES
OF SLUSHY ACCUMULATION...SO 1-3" MIGHT NOT BE A BAD BROAD BRUSH
FORECAST IN THIS CASE. SNOW RATIOS OFF THE MODELS WERE ALL OVER
THE PLACE...BUT TRIED TO STAY RIGHT AROUND 9-10:1. THIS WILL BE A
FUN ONE TO SEE PLAY OUT. GIVEN SURFACE TEMPERATURES NEAR FREEZING
WHEN THE SNOW IS FALLING...PERHAPS EVEN A DEGREE OR TWO
ABOVE...IT COULD MEAN MORE WET ROADS THAN ANYTHING ELSE. SLUSHY
ACCUMS ON LESS TRAVELED ROADS.
A LOT OF CHANCE POPS IN THE EXTENDED THAT WILL HAVE TO BE IRONED
OUT WITH TIME. IN FACT...THE GFS TONIGHT HAD AT LEAST LIGHT QPF
SOMEWHERE IN THE FORECAST AREA FROM 06Z THURSDAY TO 06Z SATURDAY.
INCREASED POPS WEDNESDAY NIGHT AND THURSDAY MORNING WITH THE WAVE
DROPPING DOWN FROM THE NORTHWEST WEDNESDAY NIGHT. THIS FEATURE
NOW LOOKS A LITTLE STRONGER THAN WHAT WE WERE SEEING YESTERDAY.
THE COMING WEEKEND STILL LOOKS A LITTLE COOLER.
&&
.AVIATION.../06Z TAF ISSUANCE/
NOT MANY CHANGES MADE TO 00Z TAFS...OTHER THAN TO INTRO ALL SN
WHERE THERE WAS ONCE A RASN MIX AT RWF/MSP/STC. LATEST 00Z MODEL
RUNS COMING IN HAVE SLOWED EVEN FURTHER WITH ONSET OF PRECIP MON
AFTERNOON/EVENING...BUT IN GENERAL MESHES WELL WITH THE 00Z
TAFS...WHICH TOOK A MORE CONSERVATIVE APPROACH TO PRECIP START
TIME. ONLY CHANGE MADE TO START TIMES WAS TO SLOW ONSET AT RWF/AXN
BY AN HOUR OR TWO. FOR CHANGEOVER TO ALL SN...00Z NAM SHOWS THIS
HAPPENING QUICKLY AFTER 00Z. PRECIP INTENSITY ALSO LOOK PRETTY
STRONG...SO TOOK VSBY DOWN TO 3/4SM IN THE SNOW...BUT LOWER VSBY
WILL PROBABLY BE NEEDED. OTHER ISSUE TO WATCH FOR TONIGHT IS BATCH
OF MVFR CLOUDS RACING NORTH ACROSS ERN SODAK. THE RUC HAS BEEN
HANDLING THESE CLOUDS QUITE WELL...AND IT RIDES THIS MOISTURE
ALMOST DUE NORTH ALONG THE SD BORDER. THIS WOULD RESULT IN THEM
ONLY GLANCING AXN...SO HAVE A BRIEF TEMPO GROUP TO START OUT...AFTER
09Z THESE CLOUDS WILL BE NORTH OF THE AREA. 00Z NAM PUTS DOWN A
PRETTY CONSISTENT 2-3 INCHES WITH THIS SNOW...WITH LESSER AMOUNTS
AT RWF...WHERE CHANGE OVER TO SNOW HAPPENS LAST. AS FOR FLIGHT
CONDITIONS...STILL LOOKING LIKELY THAT VFR CONDS PERSIST UNTIL
PRECIP STARTS...AT WHICH POINTS CIGS/VSBY QUICKLY DETERIORATE TO
IFR OR LOWER. AS THE PRECIP ENDS...STILL SEEING INDICATIONS THAT
WE LOOSE DEEP MOISTURE...WITH A PERIOD OF FZDZ POSSIBLE.
KMSP...MODELS CONTINUE SLOW ONSET OF PRECIP...AND 02Z START TIME
FOR PRECIP IS LOOKING BETTER. GIVEN WARM TEMPERATURES EXPECTED
AGAIN TODAY...EXPECT A RASN MIX TO START...BUT NAM FORECAST
SOUNDINGS CONTINUE TO SHOW THE COLUMN COOLING RAPIDLY...SO BROUGHT
IN SNOW AT 4Z...THOUGH IT MAY OCCUR A BIT EARLIER THAN THAT.
SHOULD SEE PRETTY GOOD 6 HR WINDOW OF MODERATE PRECIP BEFORE
THINGS BEGIN TO TAIL OFF TUESDAY MORNING. FORECAST SOUNDINGS STILL
INDICATING WE LOSE DEEP MOISTURE...SO ENDED PRECIP WITH THE FZDZSN
MIX. LESS CONFIDENCE ON THAT WORKING OUT THOUGH.
//OUTLOOK...TUESDAY THROUGH SATURDAY...
.TUE...MIX MVFR/VFR CIGS POSSIBLE.
.WED...MVFR/IFR POSSIBLE WITH -SN.
.THU-FRI...IFR/MVFR CONDS LIKELY WITH PERIODS OF -SN.
.SAT...VFR.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
CLF/MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1052 PM CST SUN FEB 19 2012
.UPDATE...
06Z AVIATION DISCUSSION ADDED BELOW.
&&
.DISCUSSION...
SEVERAL COMPLEX SCENARIOS FOR MON/MON EVENING SNOWFALL AMTS AND
PRECIPITATION TYPE AS A STORM SYSTEM BEGINS TO ORGANIZE ACROSS THE
PLAINS LATER TONIGHT...AND MOVES NE ON MON/MON EVENING.
AS WITH PREVIOUS SYSTEMS...AND THE OVERALL MEAN PATTERN THIS
WINTER...IT HAS BEEN INFLUENCED BY THE SOUTHERN JET STREAM. THIS
WILL LIKELY BE THE CASE WITH THIS SYSTEM...WITH MOST OF THE
MOISTURE AND DYNAMICS STAYING SOUTH AND SE OF THE FA.
THERE ARE SEVERAL WX TOOLS THAT CAN DECIPHER WHICH PRECIPITATION
TYPE WILL EVOLVE AS THIS SYSTEM BEGINS TO MOVE TO THE NE MON
MORNING. INITIALLY...THICKNESS VALUES ARE COLD ENOUGH FOR ALL
SNOW. HOWEVER...AS THE DAY PROGRESSES...1000/850MB 850/700MB AND
THE MAX WET BULB TEMP FOR A LAYER BETWEEN 0-1KM INDICATED THAT A
MIXTURE OF RAIN/SLEET/SNOW WILL DEVELOP ACROSS THE SW...AND SPREAD NE
ACROSS SOUTHERN MN DURING THE AFTN/EVENING. ONLY THE FAR NW
FA...OR AREAS ARND AXN/LXL WILL SEE ALL SNOW. DEPENDING UPON HOW
STRONG THE WAA DEVELOPS AND ASSOCIATED 85H JET...WILL DETERMINE
HOW FAR N THE MIXTURE OF RAIN/SLEET/SNOW MAKES IT INTO CENTRAL MN.
ANOTHER PROBLEM WITH THIS SYSTEM IS THE FACT THAT THE SOUTHERN JET
STREAM WILL TAKE OVER THE MAIN INFLUENCE ON PRECIPITATION
GENERATION BY LATE MON AFTN/EVENING. IN ADDITION...A DRY SLOT IS
POSSIBLE MON EVENING WHICH WILL CUT OFF ANY SIGNIFICANT SNOWFALL
AMTS ONCE THE CHG OVER BEGINS. IN ADDITION...TEMPS MON WILL LIKELY
RISE INTO THE UPPER 30S/LOWER 40S ACROSS MOST OF THE FA WHICH WILL
LEAD TO MORE MELTING AT THE SFC...OR AT LEAST ON THE
CONCRETE...WITH SLUSHY ACCUMULATIONS ON GRASSY SURFACES.
SNOWFALL TOTALS ARE BASED ON A LOW SNOW RATIO WHERE QPF IS
RELATIVELY HIGH DURING THE AFTN/EARLY EVENING OF MON...WITH
QPF AMTS LOWER ONCE THE HIGHER SNOWFALL RATIOS DEVELOP MON
EVENING. AGAIN...THIS FORECAST IS HIGHLY BASED ON THE WARMER
THICKNESS VALUES/SNOWFALL RATIOS AND QPF AMTS. ANY DEVIATION TO
THESE PARAMETERS WILL LEAD TO MORE OR LESSER SNOWFALL TOTALS BY
TUESDAY MORNING AS THE SYSTEM MOVES OFF TO THE EAST. SOMEWHAT
HIGHER AMTS COULD POSSIBLY EFFECT PORTIONS OF FAR SC MN/SE MN
AND WC WI WHERE A DEFORMATION ZONE DEVELOPS AS THE STORM SYSTEM
BECOMES MORE ORGANIZED ACROSS THE MID MISSISSIPPI VALLEY REGION MON
AFTN/EVENING.
BEYOND TUE...THE OVERALL PATTERN BECOMES MORE CONDUCIVE OF WEAK
AND RELATIVELY LOW QPF AMTS AS SEVERAL /NW FLOW/ DISTURBANCES
MOVE SE ACROSS THE NORTHERN PLAINS/UPPER MIDWEST. THICKNESS
VALUES INDICATE AT LEAST SNOW FOR THE PREDOMINATE PRECIPITATION
TYPE...BUT THAT COULD CHG BASED ON SFC TEMPS. AFT NEXT WEEK...THE
PATTERN MAY CHG ENOUGH FOR A VERY STRONG STORM SYSTEM TO AFFECT
THE UPPER MIDWEST BY THE WEEK OF FEB 27TH.
&&
.AVIATION.../06Z TAF ISSUANCE/
NOT MANY CHANGES MADE TO 00Z TAFS...OTHER THAN TO INTRO ALL SN
WHERE THERE WAS ONCE A RASN MIX AT RWF/MSP/STC. LATEST 00Z MODEL
RUNS COMING IN HAVE SLOWED EVEN FURTHER WITH ONSET OF PRECIP MON
AFTERNOON/EVENING...BUT IN GENERAL MESHES WELL WITH THE 00Z
TAFS...WHICH TOOK A MORE CONSERVATIVE APPROACH TO PRECIP START
TIME. ONLY CHANGE MADE TO START TIMES WAS TO SLOW ONSET AT RWF/AXN
BY AN HOUR OR TWO. FOR CHANGEOVER TO ALL SN...00Z NAM SHOWS THIS
HAPPENING QUICKLY AFTER 00Z. PRECIP INTENSITY ALSO LOOK PRETTY
STRONG...SO TOOK VSBY DOWN TO 3/4SM IN THE SNOW...BUT LOWER VSBY
WILL PROBABLY BE NEEDED. OTHER ISSUE TO WATCH FOR TONIGHT IS BATCH
OF MVFR CLOUDS RACING NORTH ACROSS ERN SODAK. THE RUC HAS BEEN
HANDLING THESE CLOUDS QUITE WELL...AND IT RIDES THIS MOISTURE
ALMOST DUE NORTH ALONG THE SD BORDER. THIS WOULD RESULT IN THEM
ONLY GLANCING AXN...SO HAVE A BRIEF TEMPO GROUP TO START OUT...AFTER
09Z THESE CLOUDS WILL BE NORTH OF THE AREA. 00Z NAM PUTS DOWN A
PRETTY CONSISTENT 2-3 INCHES WITH THIS SNOW...WITH LESSER AMOUNTS
AT RWF...WHERE CHANGE OVER TO SNOW HAPPENS LAST. AS FOR FLIGHT
CONDITIONS...STILL LOOKING LIKELY THAT VFR CONDS PERSIST UNTIL
PRECIP STARTS...AT WHICH POINTS CIGS/VSBY QUICKLY DETERIORATE TO
IFR OR LOWER. AS THE PRECIP ENDS...STILL SEEING INDICATIONS THAT
WE LOOSE DEEP MOISTURE...WITH A PERIOD OF FZDZ POSSIBLE.
KMSP...MODELS CONTINUE SLOW ONSET OF PRECIP...AND 02Z START TIME
FOR PRECIP IS LOOKING BETTER. GIVEN WARM TEMPERATURES EXPECTED
AGAIN TODAY...EXPECT A RASN MIX TO START...BUT NAM FORECAST
SOUNDINGS CONTINUE TO SHOW THE COLUMN COOLING RAPIDLY...SO BROUGHT
IN SNOW AT 4Z...THOUGH IT MAY OCCUR A BIT EARLIER THAN THAT.
SHOULD SEE PRETTY GOOD 6 HR WINDOW OF MODERATE PRECIP BEFORE
THINGS BEGIN TO TAIL OFF TUESDAY MORNING. FORECAST SOUNDINGS STILL
INDICATING WE LOSE DEEP MOISTURE...SO ENDED PRECIP WITH THE FZDZSN
MIX. LESS CONFIDENCE ON THAT WORKING OUT THOUGH.
//OUTLOOK...TUESDAY THROUGH SATURDAY...
.TUE...MIX MVFR/VFR CIGS POSSIBLE.
.WED...MVFR/IFR POSSIBLE WITH -SN.
.THU-FRI...IFR/MVFR CONDS LIKELY WITH PERIODS OF -SN.
.SAT...VFR.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
JLT/MPG
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
340 PM CST MON FEB 20 2012
.SHORT TERM...TONIGHT THROUGH THURSDAY.
THE MAIN CONCERNS IN THE SHORT TERM WILL BE THE COVERAGE OF THE
PRECIPITATION THAT RE-DEVELOPS AND PRECIP
TYPE...CONVECTION...RAIN/SNOW MIX.
THE 12Z UPPER AIR CHARTS SHOWED A 110+KT JET OVER NEW MEXICO
ROUNDING THE BASE OF THE TROF. THE H5 LOW WAS OVER NORTHEAST
COLORADO WITH 130M HEIGHT FALLS AT DENVER. THE H7 LOW WAS NEAR KLBF
WITH H7-H5 LAPSE RATES OF 7.5 DEG C/KM AHEAD OF THE H7 LOW. THE H85
LOW WAS NEARLY VERTICALLY STACKED BTWN RAPID CITY AND NORTH PLATTE.
BOTH DDC AND OMA REPORTED 50KT H85 WINDS. AT MIDDAY...THE SURFACE
MAP HAD SFC LOW PRESSURE NEAR LEXINGTON AND PER THE VISIBLE
STLT...THERE WAS NOTICEABLE CLEARING JUST AHEAD OF THE SFC LOW. SFC
TEMPERATURES RANGED FROM THE MID 30S IN THE NORTH TO THE MID AND
UPPER 40S TOWARD FAIRBURY AND FALLS CITY. THE WSR-88D RADAR MOSAIC
LOOP FROM THIS MORNING AND METARS SHOWED THAT TEMPERATURES WARMED
ABOVE FREEZING...HOWEVER SNOW AND SLEET DID MOVE ACROSS THE NORFOLK
AND WAYNE AREAS WITH VSBYS DOWN TO 2SM. 6HR PRECIPITATION
AMOUNTS THROUGH 18Z WERE LIGHT...GENERALLY .15 OR LESS. THERE WERE
A FEW LIGHTNING STROKES NEAR BVN/OLU/OFK. BY 19Z...THE BULK OF THE
PRECIPITATION HAD SHIFTED NORTH AND EAST OUT OF EASTERN
NEBRASKA...WITH THE NORTH TO SOUTH BAND ACROSS WRN IOWA. OUTSIDE OF
OUR AREA...WEST OF THE SURFACE LOW IN WESTERN NEBRASKA...SNOW WAS
FALLING...MODERATE TO HEAVY AT TIMES FROM VALENTINE TO IMPERIAL.
AT 21Z...A NARROW LINE OF CONVECTION WAS DEVELOPING ACROSS CENTRAL
KANSAS...WITH A FEW WARNINGS BEING ISSUED. THIS CONVECTION IS
PROGRESSING NORTH AND EAST. AT 00Z THE THETA-E AXIS IS PROGGED TO
STRETCH FROM ERN NEB INTO ERN KANSAS AND ZERO OR LOWER BEST
LIFTED INDEX VALUES ARE OVER THE NEB/KS BORDER AHEAD OF THE SFC
LOW. THE LATEST HRRR TENDS TO TAKE THE BETTER CONVECTION SOUTH OF
THE FORECAST AREA...HOWEVER...DID INCLUDE THUNDERSTORM MENTION
OVER THE SOUTHEAST NEB WITH DRIZZLE OR LIGHT RAIN FARTHER
NORTH...AND A MIX OF RAIN/SNOW MOVING EAST DURING THE EVENING.
THE RUC AND 18Z NAM SHOW THE BAND OF SNOW WEAKENING AS IT MOVES
INTO THE FORECAST AREA...HOWEVER THERE MAY BE ENOUGH
OMEGA/FRONTOGENESIS/DEPTH OF COLD AIR TO SWITCH IT OVER TO LIGHT
SNOW. DID INCLUDE SOME MINOR SNOW AMOUNTS IN PARTS OF ECNTRL/NE
NEB TO ACCOUNT FOR THIS. TREND AFTER 06Z IS FOR THE SYSTEM TO BE
MOVING OUT...WITH WESTERLY FLOW FOR TUESDAY.
LATE TUESDAY NIGHT INTO WEDNESDAY NIGHT...NORTHWEST FLOW ALOFT
WILL BRING MODERATE TEMPERATURES AND VARIABLE CLOUDS. THE MODELS
HAVE SOME DIFFERENCES ON THE CHC FOR PRECIPITATION DURING THIS
PERIOD. FOR NOW INCLUDED SOME SPRINKLES WEDNESDAY AND WITH THE
COLDER AIR WEDNESDAY NIGHT AND THURSDAY...A RAIN SNOW MIX IN THE
NORTH.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY.THE LONG TERM PERIOD
WILL BEGIN WITH AN UPPER TROUGH OVER THE GREAT LAKES AND THE
EASTERN NORTHERN PLAINS. A SHORTWAVE SHOULD BE EXITING OUR AREA
THURSDAY NIGHT SO WILL MAINTAIN A DRY FORECAST THEN. ANOTHER
SHORTWAVE LOOKS TO DROP THROUGH THE NORTHWEST FLOW ON BACK SIDE OF
UPPER TROUGH ON FRIDAY...WITH MODELS SHOWING VARYING DEGREES OF
INTENSITY AND LOCATION. GFS IS THE STRONGEST AND FARTHEST
WEST...WHICH WOULD BRING A CHANCE FOR LIGHT SNOW TO OUR
AREA...WHILE ECMWF/CANADIAN TRACK SHORTWAVE TO OUR EAST. WILL STAY
WITH MAJORITY OF MODEL SOLUTIONS WHICH MATCH OUR CURRENT DRY
FORECAST. HOWEVER ALL SOLUTIONS SUGGEST A RATHER CHILLY DAY FRIDAY
AS AT LEAST MODERATE COLD ADVECTION SHOULD KEEP HIGHS IN THE 30S.
A WARMING TREND STILL LOOKS ON TAP FOR THE WEEKEND AS UPPER FLOW
BECOMES MORE ZONAL IN WAKE OF EXITING UPPER TROUGH AND AHEAD OF
LOWERING HEIGHTS ALONG THE WEST COAST. AGAIN TODAY MODELS HAVE
DIFFERING OPINIONS ON TIMING AND EXTENT OF WARMING BASED ON
DIFFERING UPPER FLOW SOLUTIONS. FOR THE MOST PART...ALL MODELS SHOW
LOWERING HEIGHTS IN THE WEST...BUT SOME ARE HINTING AT A SIGNIFICANT
PIECE OF ENERGY MOVING FROM THE ROCKIES ACROSS THE PLAINS ON SUNDAY.
GFS IS THE MOST BULLISH IN THIS REGARD...AND HAS NOT WAVERED FROM
RUN TO RUN. HOWEVER...GFS ENSEMBLE MEMBERS ARE SPLIT...WITH A
PLURALITY LEANING TOWARD A 00Z ECMWF SOLUTION KEEPING MORE ENERGY
DROPPING INTO THE SOUTHWEST STATES AND MAINTAINING ZONAL OR
SOUTHWEST FLOW ALOFT IN THE PLAINS THROUGH SUNDAY. THE NEW 12Z ECMWF
MAINTAINS THIS PHILOSOPHY...SO HAVE SIDED WITH THIS THOUGHT FOR THE
WEEKEND.
USING ECMWF...HIGHS SATURDAY SHOULD REBOUND BACK INTO THE
40S BUT SUNDAY IS STILL IN QUESTION. BAROCLINIC ZONE LOOKS TO SET UP
NORTH TO SOUTH ACROSS OUR CWA WITH THE 0C 850 LINE NEAR INTERSTATE
80. STRONG ISENTROPIC UPGLIDE WILL COMMENCE SUNDAY AFTERNOON UNDER
COUPLED JET STRUCTURE...SUGGESTING LIFT OVER BAROCLINIC ZONE COULD
LEAD TO PRECIPITATION IN OUR NORTH. THICKNESSES SUPPORT SNOW
THERE...BUT WARM LOW LEVEL TEMPS COULD CHANGE THAT TO RAIN. SO A MIX
OF PRECIP WILL BE ADDED TO FORECAST SUNDAY. CLOUDS AND
PRECIPITATION CHANCES WILL LIKELY LIMIT HIGHS TO THE 30S IN OUR
NORTH. THIS TREND CONTINUES INTO MONDAY AS SURFACE LOW TRACKS TO OUR
SOUTH...MAINTAINING BAROCLINICITY ACROSS OUR AREA WITH A NORTHWEST
TO SOUTHEAST ORIENTATION. TRACK OF LOW PUTS OUR SOUTHEAST CWA IN
FAVORABLE AREA FOR RAIN THEN...WITH HIGHS RANGING FROM THE 20S OR
LOWER 30S NORTHWEST TO THE UPPER 30S SOUTHEAST. THERE IS A LOT OF
ROOM FOR ERROR SUNDAY AND MONDAY GIVEN PROXIMITY OF BAROCLINIC
ZONE...SO RELATIVELY LOW CONFIDENCE FORECAST AT THIS TIME.
&&
.AVIATION...
18Z TAFS FOR KOFK...KOMA AND KLNK.
MVFR CIGS CURRENTLY COVERING MAJORITY OF ERN NEB...WITH IFR CIGS AND
SCT PCPN WRAPPING AROUND BACKSIDE OF DEEP SFC LOW PRESSURE CENTERED
IN SRN NEB. FOR THIS TAF CYCLE...PIVOTING SFC LOW AND DRY AIR
INTRUSION FROM THE SOUTHWEST MAKING FLIGHT CAT FORECAST RATHER
COMPLICATED. AT THIS POINT FEEL THAT IFR CONDITIONS WILL BE MOST
PREVALENT AT KOFK UNTIL ABOUT 21/04Z WITH TEMPO FOR PCPN BTWN 20
/21Z-24Z. CONDITIONS THEN IMPROVING MVFR TO VFR AROUND 21/11Z.
FOR KOMA AND KLNK...EXPECT MVFR CONDITIONS WILL PREVAIL AT BOTH
SITES THROUGH ABOUT 21/09Z. HOWEVER...AS SFC LOW MIGRATES
EAST...NARROW BAND OF PCPN MAY DEVELOP ALONG THE NEB/IA BORDER
LATE THIS AFTERNOON THUS HAVE PCPN PREVAILING AT KOMA THROUGH LATE
THIS EVENING.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY/DERGAN/DEE
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
825 PM CST TUE FEB 21 2012
.DISCUSSION...FORECAST CHALLENGE FOR UPDATE CONCERNS CLOUD TRENDS
AND TEMPERATURES. WESTERN EDGE OF CLOUD SHIELD ACROSS W-SW FA
BECOMING RAGGED WITH SOME CLEARING TAKING PLACE. RUC SEEMS TO BE
DOING A GOOD JOB WITH CLOUD TRENDS WHEN COMPARED WITH 925-850MB RH
LAYER. COULD SEE SOME CLEARING AS FAR EAST AS VALLEY BEFORE CLOUDS
MOVE BACK IN TOWARDS MORNING. WITH CONFIDENCE GROWING WITH CLOUD
TRENDS WILL MAKE SOME MINOR TEMPERATURE ADJUSTMENTS COOLING THINGS
DOWN ACROSS SW FA AND A LITTLE WARMER THROUGH THE VALLEY WHERE
TEMPERATURES HOLDING UP. STILL SEEING SOME -SN/FLURRIES ACROSS THE
EAST AND WILL MAINTAIN MENTION OVERNIGHT.
&&
.AVIATION...MVFR CIGS PERSIST ACROSS EASTERN FA AFFECTING TVF/BJI
TAF SITES AND WILL LIKELY PERSIST A GOOD PART OF THE OVERNIGHT. SOME
MINOR RESTRICTION TO VSBY IN -SN BUT FOR THE MOST PART WILL REMAIN
VFR.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
VOELKER
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
954 PM EST TUE FEB 21 2012
.SYNOPSIS...
HIGH PRESSURE WILL MOVE INTO THE AREA BEHIND A DEPARTING COLD FRONT.
A STRONGER FRONT IS EXPECTED TO MOVE INTO THE CAROLINAS EARLY ON
FRIDAY. HIGH PRESSURE WILL THEN RETURN OVER THE WEEKEND AND LINGER
INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 950 PM TUE...THE HRRR AND WORKSTATION WRF...ALONG WITH THE 18
UTC NAM BUFKIT...CONTINUE TO SHOW STRATUS DEVELOPING OVER NE
GA...THE UPSTATE AND THE SRN NC PIEDMONT LATE TONIGHT. AND THE MAJOR
MODEL MOS PRODUCTS CONTINUE TO SHOW NOTHING. I/VE UPPED SKY COVER
LATE TONIGHT AND A COUPLE HOURS AFTER SUNRISE ON WEDNESDAY IN THIS
AREA. THE GRIDS MAY UNLOAD WITH A BRIEF PERIOD OF MOSTLY CLOUDY.
THIS WILL BE MORE IMPORTANT FOR TAF GENERATION PURPOSES LATER
TONIGHT. OTHERWISE...I/VE RAISED DEWPOINTS ACROSS THE SOUTH ONCE
AGAIN. THE WINDS HAVE DECOUPLE QUICKLY THIS EVENING...BUT SHOULD
INCREASE INTO THE 4 TO 6 KT RANGE LATER TONIGHT AND THE LLVL JET
STRENGTHENS TO AROUND 30 KTS OVER THE FA.
AS OF 650 PM TUE...GRIDS ARE IN GOOD SHAPE RIGHT NOW. UPPED THE
DEWPOINTS A LITTLE OVERNIGHT. AN AXIS OF HIGHER BNDRY LAYER
DEWPOINTS WILL BECOME ORIENTED OVER THE FOOTHILLS AND PIEDMONT LATE
TONIGHT. THE RUC BNDRY LAYER DEWPOINTS INCREASE TO NEAR 50 DEG F
OVER THE SRN PART OF THE FA...WHICH IS A HAIR WARMER THAN THE
CURRENT SOIL TEMPERATURES. WITH MODEST LLVL WARM ADVECTION...THIS
COULD TRANSLATE INTO A NICE STRATUS DECK ALONG THE I-85 CORRIDOR
LATE TONIGHT. I/VE TWEAKED CLOUD COVER UP A LITTLE TO ACCOUNT FOR
THIS...BUT WIL WAIT THE 00 UTC MODEL RUNS BEFORE MAKING ANY LARGE
UPWARD ADJUSTMENT.
PREVIOUS DISCUSSION...
GUIDANCE IN GOOD AGREEMENT THIS PERIOD. A WEAK FRONT CROSSES THE
CWFA BY THIS EVENING BRINGING CLOUDS ACROSS THE AREA. GUSTY WINDS
WILL DIMINISH THIS EVENING BEHIND THE FRONT AS WILL CLOUDS. LOWS
WILL BE AROUND 5 DEGREES ABOVE NORMAL.
A SHORT WAVE ENTERS THE AREA WED AFTERNOON AS MID LEVEL FLOW BECOMES
A LITTLE MORE AMPLIFIED. ANOTHER SLIGHTLY STRONGER FRONT WILL MOVE
INTO THE AREA AS WELL. FORCING AND MOISTURE IS BETTER WITH THIS
SYSTEM. THAT SAID...THE FORCING IS NOT VERY STRONG WITH ONLY WEAK
UPPER DIVERGENCE. THE MOISTURE IS NOT VERY COPIOUS EITHER. STILL...
IT APPEARS THAT THEY WILL BE ENUF FOR GOOD CHC POP TO DEVELOP OVER
THE MTNS. POP DROPS OFF TO SLIGHT CHC SOUTH OF I-85 AWAY FROM THE
BEST MOISTURE AND FORCING. INSTABILITY IS ON THE UPSWING DURING THE
AFTERNOON...BUT IT REMAINS QUESTIONABLE WHETHER IT BECOMES STRONG
ENUF FOR ANY TSRA TO DEVELOP. THEREFORE...HAVE CONTINUED THE PREV
TREND OF NO TS MENTION FOR NOW. SHOULD BE ANOTHER GUSTY AFTERNOON AS
DEEP MIXING TAPS RELATIVELY STRONG LOW LEVEL FLOW. IN FACT...IT
COULD BE STRONG ENUF FOR A LAKE WIND ADV. WILL LET NEXT SHIFT MAKE
THAT DECISION AS THE MAGNITUDE IS STILL IN QUESTION. HIGHS WILL BE 5
TO 10 DEGREES ABOVE NORMAL.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 230 PM TUESDAY...A WARM AND MOIST AIR MASS WILL DEVELOP OVER
THE REGION DURING THE MID WEEK. WEDNESDAY EVENING...A SHORT WAVE IS
EXPECTED TO RIPPLE WITHIN A LONGWAVE TROF AXIS ACROSS THE SOUTHERN
APPALACHIAN REGION DURING THE EARLY EVENING HOURS. GUSTY SOUTHWEST
WINDS ARE FORECAST TO BRING RISING DEWPOINTS ACROSS THE FORECAST
AREA...GENERALLY RANGING IN THE MID TO UPPER 40S. AN AREA OF
TSRA/SHRA IS EXPECTED TO DEVELOP DURING THE AFTERNOON UPSTREAM OF
THE REGION...STEERING FLOW WILL TRANSPORT THE CONVECTION NORTHEAST
ACROSS GEORGIA AND THE WESTERN CAROLINAS. DURING THE EVENING
HOURS...FORECAST SOUNDINGS INDICATE THAT CAPE VALUES WILL RANGE FROM
100 TO 400 J/KG ACROSS THE CWA. IN ADDITION...SWEAT VALUES WILL PEAK
BETWEEN 300-400 WITH EHI VALUES AROUND 1...THE CORE OF A H3 140 KT
JET WILL REMAIN ACROSS THE MIDLANDS AND COASTAL AREAS. GIVEN THE
BROAD FIELD OF WEAK INSTABILITY AND STRONG WIND FIELDS...IT IS
REASONABLE TO EXPECT ORGANIZED MCS TO SURVIVE INTO THE EVENING HOURS
ACROSS THE CWA. I WILL MAINTAIN CHC POPS ACROSS THE MTNS AND
FOOTHILLS...SCHC EAST OF I-85. THE POTENTIAL EXIST THAT ANY
ORGANIZED CONVECTION COULD PRODUCE DAMAGING WINDS DURING THE
EVENING...SUPPORTED BY SPC DY2 SLIGHT RISK AREA. I WILL HIGHLIGHT
THE RISK FOR DAMAGING TSRA WINDS IN THE HWO.
THROUGH THE REST OF WEDNESDAY NIGHT...ONGOING SOUTHWEST WINDS AND
THICK SKY COVER WILL KEEP TEMPERATURES MILD OVERNIGHT. USING A BLEND
OF GUIDANCE...I WILL FORECAST LOWS FROM THE L40S ACROSS THE MTNS TO
L50S EAST.
THURSDAY...PRESSURE GRADIENT ACROSS THE FORECAST AREA WILL REMAIN
BETWEEN 3 TO 4 MBS. FORECAST SOUNDINGS INDICATE THE MIXING MAY
REACH UP TO H85 DURING THE AFTERNOON. SOUTHWEST WINDS WILL LIKELY
INCREASE THROUGH THE DAY...PEAKING BETWEEN 15 TO 20 KTS WITH GUSTS
TO 25 TO 30 KTS. THESE WINDS WILL REINFORCE THE WARM AND MOIST AIR
MASS ACROSS THE REGION...WITH DEWPOINTS REMAINING WELL INTO THE 40S.
H85 TEMPS MAY REACH ABOVE 10C DURING THE AFTERNOON AS A COLD FRONT
PUSHES INTO MIDDLE TN. MOS CONSENSUS SUPPORTS HIGH TEMPERATURES IN
THE U60S ACROSS THE MTNS VALLEYS TO LOW TO MID 70S EAST...OR WITHIN
A COUPLE OF DEGREES OF RECORD HIGHS.
THURSDAY NIGHT...NAM AND GFS INDICATE THAT COLD FRONT WILL SWEEP
ACROSS THE SOUTHERN APPALACHIAN REGION DURING THE LATE NIGHT HOURS.
WIND FIELDS ALONG AND AHEAD OF THE FRONT BECOME STRONG WITH 0 TO 1
KM HELICITY EXCEEDING 300 M2/S2. NAM CAPE SHOWS THAT A BAND OF WEAK
CAPE WILL REMAIN ALONG AND AHEAD OF THE FRONT. THIS ENVIRONMENT MAY
SUPPORT ONGOING GA/TN MCS TO TRACK ACROSS THE REGION DURING THE
NIGHT. THESE SITUATIONS TYPICALLY BRING TSRA EAST QUICKER THAN
MODEL RATES...BUT EVEN USING THE MORE STABLE GUIDANCE IT APPEARS
THAT SVR WINDS ARE POSSIBLE. WE WILL ALSO HIGHLIGHT THIS EVENT IN
THE HWO. MIN TEMPERATURES ARE FORECAST TO RANGE FROM U40S ACROSS THE
MTN VALLEYS TO LOW TO MID 50S EAST.
FRIDAY...WINDS WILL VEER WEST TO EVENTUALLY NORTHWEST IN THE WAKE OF
THE COLD FRONT. I WILL INDICATE DECREASING POPS AND SKY WITH THE
PASSAGE OF THE FRONT. MODELS INDICATE THAT H85 TEMPS WILL FALL
THROUGH THE DAY...WITH TEMPS COOLING BETWEEN 8 TO 10 C DURING THE
DAYLIGHT HOURS. I WILL WILL INDICATE A MID DAY HIGH IN THE U50S
ACROSS THE MTNS TO U60S EAST...THEN GRADUAL COOLING THROUGH THE
AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 2 PM TUESDAY...THE GLOBAL MODELS ARE HAVING TYPICAL ISSUES
WITH THE SPLIT FLOW REGIME IN PLACE AT THE BEGINNING OF THE PERIOD.
THEREFORE...CONFIDENCE IN THE MEDIUM RANGE FORECAST IS MUCH LOWER
THAN USUAL. THE MAIN PROBLEMS ARE IN THE SOUTHERN STREAM...
SPECIFICALLY IN TIMING THE KICKING OUT OF THE UPPER LOW THAT IS
CURRENTLY OVER THE BAJA AREA. THE 00Z ECMWF KICKS THIS ENERGY OUT
OVER THE SOUTHEAST FRIDAY (ABOUT 24 HOURS LATER THAN YESTERDAYS
RUNS). MEANWHILE...THE GFS DOESNT DO THIS UNTIL SUNDAY NIGHT. THE
MODELS HAVE BEEN UP TO THESE TYPES OF SHENANIGANS FOR SEVERAL DAYS
NOW WITH REGARD TO THIS SOUTHERN STREAM ENERGY AND WHETHER/WHEN TO
TRANSITION TO A PHASED FLOW REGIME. WE/VE OPTED TO STOP PRETENDING
THAT WE OR THE MODELS HAVE ANY CLUE WHAT/S GOING TO HAPPEN PAST THE
SHORT TERM PERIOD. POPS WILL THEREFORE BE HELD BELOW CHANCE THROUGH
THE MEDIUM RANGE...WHILE NEAR-NORMAL TEMPS WILL BE FORECAST IN THE
WAKE OF FRIDAYS FROPA.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE...STRATO-CU DECK HAS THINNED AND GENERALLY
MOVED EAST OF MOST OF THE TAF SITES. HOWEVER...IT MAY START TO BUILD
BACK TO THE WEST A LITTLE THIS EVENING. FOR NOW...I/VE GOT A COUPLE
MORE HOURS OF BKN040 CIGS AT KCLT...WITH FEW/SCT AT THE REMAINING
SITES. WINDS WILL BE SOUTHWEST THIS EVENING AND LIGHT AND VARIABLE
OVERNIGHT. WINDS TMRW WILL BECOME GUSTY IN THE AFTN. FOR NOW THEY/VE
BEEN CAPPED AT ABOUT 25 KTS...BUT THEY COULD GUST AS HIGH AS 30 KTS
OVER THE UPSTATE AND AT KCLT.
LATE TONIGHT THE OPERATIONAL NAM...WORKSTATION WRF AND THE RUC
DEVELOP CIGS IN THE 800 TO 1000 FOOT RANGE OVER PRETTY MUCH ALL THE
FOOTHILL AND PIEDMONT TAF SITES. THE SREF PROBS AND OPERATIONAL MOS
GUIDANCE DO NOT HAVE THIS. I/VE ADDED FEW TO SCT010 TO THE SITES
ALONG THE I-85 CORRIDOR. IT/S HARD TO IGNORE A MOIST LAYER LIKE THE
ONE SHOWING UP ON THE NAM BUFKIT SOUNDINGS...SO WHILE THE SREF PROBS
ARE UNDER 10 PERCENT...CONFIDENCE IS INCREASING IN THE DEVELOPMENT
OF LOW CIGS LATE TONIGHT. BY MID AFTN...CU SHOULD BUILD INTO A FEW
SHRA/TSTMS OVER THE MTNS AND CB/S HAVE BEEN ADDED TO KAVL.
OUTLOOK...PCPN CHANCES WILL GRADUALLY INCREASE WED AFTERNOON AND
CONTINUE THRU THU. LOWERING CIGS AND VSBYS ALSO ARE EXPECTED DURING
THIS TIME. GUSTY SW WINDS WILL DEVELOP AGAIN ON THU. LOW PRESSURE
WILL DEVELOP OVER THE DEEP SOUTH THU NIGHT AND FRI. WIDESPREAD LOW
CIGS AND PCPN ARE EXPECTED AS THE LOW DEVELOPS. DRIER AND COLDER
WEATHER WILL FOLLOW FOR THE WEEKEND.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...MCAVOY
SHORT TERM...NED
LONG TERM...JDL
AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
704 PM EST TUE FEB 21 2012
.SYNOPSIS...
HIGH PRESSURE WILL MOVE INTO THE AREA BEHIND A DEPARTING COLD FRONT.
A STRONGER FRONT IS EXPECTED TO MOVE INTO THE CAROLINAS EARLY ON
FRIDAY. HIGH PRESSURE WILL THEN RETURN OVER THE WEEKEND AND LINGER
INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
GRIDS ARE IN GOOD SHAPE RIGHT NOW. UPPED THE DEWPOINTS A LITTLE
OVERNIGHT. AN AXIS OF HIGHER BNDRY LAYER DEWPOINTS WILL BECOME
ORIENTED OVER THE FOOTHILLS AND PIEDMONT LATE TONIGHT. THE RUC BNDRY
LAYER DEWPOINTS INCREASE TO NEAR 50 DEG F OVER THE SRN PART OF THE
FA...WHICH IS A HAIR WARMER THAN THE CURRENT SOIL TEMPERATURES. WITH
MODEST LLVL WARM ADVECTION...THIS COULD TRANSLATE INTO A NICE
STRATUS DECK ALONG THE I-85 CORRIDOR LATE TONIGHT. I/VE TWEAKED
CLOUD COVER UP A LITTLE TO ACCOUNT FOR THIS...BUT WIL WAIT THE 00
UTC MODEL RUNS BEFORE MAKING ANY LARGE UPWARD ADJUSTMENT.
PREVIOUS DISCUSSION...
GUIDANCE IN GOOD AGREEMENT THIS PERIOD. A WEAK FRONT CROSSES THE
CWFA BY THIS EVENING BRINGING CLOUDS ACROSS THE AREA. GUSTY WINDS
WILL DIMINISH THIS EVENING BEHIND THE FRONT AS WILL CLOUDS. LOWS
WILL BE AROUND 5 DEGREES ABOVE NORMAL.
A SHORT WAVE ENTERS THE AREA WED AFTERNOON AS MID LEVEL FLOW BECOMES
A LITTLE MORE AMPLIFIED. ANOTHER SLIGHTLY STRONGER FRONT WILL MOVE
INTO THE AREA AS WELL. FORCING AND MOISTURE IS BETTER WITH THIS
SYSTEM. THAT SAID...THE FORCING IS NOT VERY STRONG WITH ONLY WEAK
UPPER DIVERGENCE. THE MOISTURE IS NOT VERY COPIOUS EITHER. STILL...
IT APPEARS THAT THEY WILL BE ENUF FOR GOOD CHC POP TO DEVELOP OVER
THE MTNS. POP DROPS OFF TO SLIGHT CHC SOUTH OF I-85 AWAY FROM THE
BEST MOISTURE AND FORCING. INSTABILITY IS ON THE UPSWING DURING THE
AFTERNOON...BUT IT REMAINS QUESTIONABLE WHETHER IT BECOMES STRONG
ENUF FOR ANY TSRA TO DEVELOP. THEREFORE...HAVE CONTINUED THE PREV
TREND OF NO TS MENTION FOR NOW. SHOULD BE ANOTHER GUSTY AFTERNOON AS
DEEP MIXING TAPS RELATIVELY STRONG LOW LEVEL FLOW. IN FACT...IT
COULD BE STRONG ENUF FOR A LAKE WIND ADV. WILL LET NEXT SHIFT MAKE
THAT DECISION AS THE MAGNITUDE IS STILL IN QUESTION. HIGHS WILL BE 5
TO 10 DEGREES ABOVE NORMAL.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 230 PM TUESDAY...A WARM AND MOIST AIR MASS WILL DEVELOP OVER
THE REGION DURING THE MID WEEK. WEDNESDAY EVENING...A SHORT WAVE IS
EXPECTED TO RIPPLE WITHIN A LONGWAVE TROF AXIS ACROSS THE SOUTHERN
APPALACHIAN REGION DURING THE EARLY EVENING HOURS. GUSTY SOUTHWEST
WINDS ARE FORECAST TO BRING RISING DEWPOINTS ACROSS THE FORECAST
AREA...GENERALLY RANGING IN THE MID TO UPPER 40S. AN AREA OF
TSRA/SHRA IS EXPECTED TO DEVELOP DURING THE AFTERNOON UPSTREAM OF
THE REGION...STEERING FLOW WILL TRANSPORT THE CONVECTION NORTHEAST
ACROSS GEORGIA AND THE WESTERN CAROLINAS. DURING THE EVENING
HOURS...FORECAST SOUNDINGS INDICATE THAT CAPE VALUES WILL RANGE FROM
100 TO 400 J/KG ACROSS THE CWA. IN ADDITION...SWEAT VALUES WILL PEAK
BETWEEN 300-400 WITH EHI VALUES AROUND 1...THE CORE OF A H3 140 KT
JET WILL REMAIN ACROSS THE MIDLANDS AND COASTAL AREAS. GIVEN THE
BROAD FIELD OF WEAK INSTABILITY AND STRONG WIND FIELDS...IT IS
REASONABLE TO EXPECT ORGANIZED MCS TO SURVIVE INTO THE EVENING HOURS
ACROSS THE CWA. I WILL MAINTAIN CHC POPS ACROSS THE MTNS AND
FOOTHILLS...SCHC EAST OF I-85. THE POTENTIAL EXIST THAT ANY
ORGANIZED CONVECTION COULD PRODUCE DAMAGING WINDS DURING THE
EVENING...SUPPORTED BY SPC DY2 SLIGHT RISK AREA. I WILL HIGHLIGHT
THE RISK FOR DAMAGING TSRA WINDS IN THE HWO.
THROUGH THE REST OF WEDNESDAY NIGHT...ONGOING SOUTHWEST WINDS AND
THICK SKY COVER WILL KEEP TEMPERATURES MILD OVERNIGHT. USING A BLEND
OF GUIDANCE...I WILL FORECAST LOWS FROM THE L40S ACROSS THE MTNS TO
L50S EAST.
THURSDAY...PRESSURE GRADIENT ACROSS THE FORECAST AREA WILL REMAIN
BETWEEN 3 TO 4 MBS. FORECAST SOUNDINGS INDICATE THE MIXING MAY
REACH UP TO H85 DURING THE AFTERNOON. SOUTHWEST WINDS WILL LIKELY
INCREASE THROUGH THE DAY...PEAKING BETWEEN 15 TO 20 KTS WITH GUSTS
TO 25 TO 30 KTS. THESE WINDS WILL REINFORCE THE WARM AND MOIST AIR
MASS ACROSS THE REGION...WITH DEWPOINTS REMAINING WELL INTO THE 40S.
H85 TEMPS MAY REACH ABOVE 10C DURING THE AFTERNOON AS A COLD FRONT
PUSHES INTO MIDDLE TN. MOS CONSENSUS SUPPORTS HIGH TEMPERATURES IN
THE U60S ACROSS THE MTNS VALLEYS TO LOW TO MID 70S EAST...OR WITHIN
A COUPLE OF DEGREES OF RECORD HIGHS.
THURSDAY NIGHT...NAM AND GFS INDICATE THAT COLD FRONT WILL SWEEP
ACROSS THE SOUTHERN APPALACHIAN REGION DURING THE LATE NIGHT HOURS.
WIND FIELDS ALONG AND AHEAD OF THE FRONT BECOME STRONG WITH 0 TO 1
KM HELICITY EXCEEDING 300 M2/S2. NAM CAPE SHOWS THAT A BAND OF WEAK
CAPE WILL REMAIN ALONG AND AHEAD OF THE FRONT. THIS ENVIRONMENT MAY
SUPPORT ONGOING GA/TN MCS TO TRACK ACROSS THE REGION DURING THE
NIGHT. THESE SITUATIONS TYPICALLY BRING TSRA EAST QUICKER THAN
MODEL RATES...BUT EVEN USING THE MORE STABLE GUIDANCE IT APPEARS
THAT SVR WINDS ARE POSSIBLE. WE WILL ALSO HIGHLIGHT THIS EVENT IN
THE HWO. MIN TEMPERATURES ARE FORECAST TO RANGE FROM U40S ACROSS THE
MTN VALLEYS TO LOW TO MID 50S EAST.
FRIDAY...WINDS WILL VEER WEST TO EVENTUALLY NORTHWEST IN THE WAKE OF
THE COLD FRONT. I WILL INDICATE DECREASING POPS AND SKY WITH THE
PASSAGE OF THE FRONT. MODELS INDICATE THAT H85 TEMPS WILL FALL
THROUGH THE DAY...WITH TEMPS COOLING BETWEEN 8 TO 10 C DURING THE
DAYLIGHT HOURS. I WILL WILL INDICATE A MID DAY HIGH IN THE U50S
ACROSS THE MTNS TO U60S EAST...THEN GRADUAL COOLING THROUGH THE
AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 2 PM TUESDAY...THE GLOBAL MODELS ARE HAVING TYPICAL ISSUES
WITH THE SPLIT FLOW REGIME IN PLACE AT THE BEGINNING OF THE PERIOD.
THEREFORE...CONFIDENCE IN THE MEDIUM RANGE FORECAST IS MUCH LOWER
THAN USUAL. THE MAIN PROBLEMS ARE IN THE SOUTHERN STREAM...
SPECIFICALLY IN TIMING THE KICKING OUT OF THE UPPER LOW THAT IS
CURRENTLY OVER THE BAJA AREA. THE 00Z ECMWF KICKS THIS ENERGY OUT
OVER THE SOUTHEAST FRIDAY (ABOUT 24 HOURS LATER THAN YESTERDAYS
RUNS). MEANWHILE...THE GFS DOESNT DO THIS UNTIL SUNDAY NIGHT. THE
MODELS HAVE BEEN UP TO THESE TYPES OF SHENANIGANS FOR SEVERAL DAYS
NOW WITH REGARD TO THIS SOUTHERN STREAM ENERGY AND WHETHER/WHEN TO
TRANSITION TO A PHASED FLOW REGIME. WE/VE OPTED TO STOP PRETENDING
THAT WE OR THE MODELS HAVE ANY CLUE WHAT/S GOING TO HAPPEN PAST THE
SHORT TERM PERIOD. POPS WILL THEREFORE BE HELD BELOW CHANCE THROUGH
THE MEDIUM RANGE...WHILE NEAR-NORMAL TEMPS WILL BE FORECAST IN THE
WAKE OF FRIDAYS FROPA.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE...STRATO-CU DECK HAS THINNED AND GENERALLY
MOVED EAST OF MOST OF THE TAF SITES. HOWEVER...IT MAY START TO BUILD
BACK TO THE WEST A LITTLE THIS EVENING. FOR NOW...I/VE GOT A COUPLE
MORE HOURS OF BKN040 CIGS AT KCLT...WITH FEW/SCT AT THE REMAINING
SITES. WINDS WILL BE SOUTHWEST THIS EVENING AND LIGHT AND VARIABLE
OVERNIGHT. WINDS TMRW WILL BECOME GUSTY IN THE AFTN. FOR NOW THEY/VE
BEEN CAPPED AT ABOUT 25 KTS...BUT THEY COULD GUST AS HIGH AS 30 KTS
OVER THE UPSTATE AND AT KCLT.
LATE TONIGHT THE OPERATIONAL NAM...WORKSTATION WRF AND THE RUC
DEVELOP CIGS IN THE 800 TO 1000 FOOT RANGE OVER PRETTY MUCH ALL THE
FOOTHILL AND PIEDMONT TAF SITES. THE SREF PROBS AND OPERATIONAL MOS
GUIDANCE DO NOT HAVE THIS. I/VE ADDED FEW TO SCT010 TO THE SITES
ALONG THE I-85 CORRIDOR. IT/S HARD TO IGNORE A MOIST LAYER LIKE THE
ONE SHOWING UP ON THE NAM BUFKIT SOUNDINGS...SO WHILE THE SREF PROBS
ARE UNDER 10 PERCENT...CONFIDENCE IS INCREASING IN THE DEVELOPMENT
OF LOW CIGS LATE TONIGHT. BY MID AFTN...CU SHOULD BUILD INTO A FEW
SHRA/TSTMS OVER THE MTNS AND CB/S HAVE BEEN ADDED TO KAVL.
OUTLOOK...PCPN CHANCES WILL GRADUALLY INCREASE WED AFTERNOON AND
CONTINUE THRU THU. LOWERING CIGS AND VSBYS ALSO ARE EXPECTED DURING
THIS TIME. GUSTY SW WINDS WILL DEVELOP AGAIN ON THU. LOW PRESSURE
WILL DEVELOP OVER THE DEEP SOUTH THU NIGHT AND FRI. WIDESPREAD LOW
CIGS AND PCPN ARE EXPECTED AS THE LOW DEVELOPS. DRIER AND COLDER
WEATHER WILL FOLLOW FOR THE WEEKEND.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...MCAVOY
SHORT TERM...NED
LONG TERM...JDL
AVIATION...MCAVOY
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1145 PM CST SUN FEB 19 2012
.UPDATE...
UPDATED 06Z AVIATION DISCUSSION BELOW...
ECHOES ALREADY BEGINNING TO DEVELOP ON AREA RADARS LATE THIS
EVENING. THESE WILL CONTINUE TO EXPAND AND INCREASE IN INTENSITY
THROUGH THE NIGHT. THE LATEST HRRR MODEL SHOWS SNOW DEVELOPING IN
PIERRE BY 3 AM OR SO AND SPREADING NORTHEAST TO ABERDEEN BY 7 AM.
CURRENT FORECAST SHOWS THIS WELL IN THE GRIDS. THE WINTER WEATHER
ADVISORY LOOKS GOOD.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
MAIN FORECAST CHALLENGE IS PRECIPITATION TYPE/CHANGEOVER TIME-FRAME.
MODEL GUIDANCE BEGINNING TO COME SOMEWHAT MORE IN LINE WITH EACH
OTHER REGARDING PRECIPITATION TYPE. WET BULB ZERO TEMPS ARE COLD IN
ADDITION...MOST MODELS FARTHER WEST WITH PRECIPITATION/SNOW AS A
STRONG MID-LEVEL DEFORMATION ZONE SETS UP JUST EAST OF THE MO
RIVER MONDAY MORNING...SLIDING EAST DURING THE AFTERNOON. ISSUED
WINTER WEATHER ADVISORY FOR ZONES EAST OF THE MISSOURI RIVER GIVEN
GOOD QPF AGREEMENT AND MOST MODELS COLD ENOUGH FOR ALL SNOW WEST
OF U.S. HIGHWAY 83 THROUGH AROUND 18Z. FAIRLY DEEP ISOTHERMAL
LAYER FROM THE SFC TO ABOUT H85 MAKING THIS SNOW ACCUMULATION
FORECASTS QUITE THE CHALLENGE. IF SNOW INTENSITY IS NOT SUFFICIENT...SOME
AREAS MAY SEE SNOW FALLING THROUGH THE DAY BUT LITTLE IN THE WAY
OF ACCUMULATION. OTHER LOCATIONS COULD BE A RAIN/SNOW MIX DURING
THE AFTERNOON OR A SNOW/SLEET MIX DURING THE MORNING...CUTTING
DOWN ON ACCUMULATION AMOUNTS. EITHER WAY...STILL LOOKS LIKE
ACCUMULATING SNOWS FOR THE MAJORITY OF THE AREA LATE TONIGHT
THROUGH MONDAY WITH BRIEF HEAVY SNOW A POSSIBILITY ALONG A LARGE
SNOW BAND ASSOCIATED WITH THE STRONGEST AREA OF MID-LEVEL
DEFORMATION/STRETCHING. SNOW SLIDES EAST OF THE REGION MONDAY
EVENING...WITH A DRY NORTHWEST FLOW ALOFT MOVING IN. A WEAK
CLIPPER SHORT-WAVE TROUGH WILL BRING SLIGHT CHANCES FOR SOME LIGHT
SNOW TUESDAY NIGHT AS ASCENT ASSOCIATED WITH A 135 KT JET NOSES
INTO WRN SD.
.LONG TERM...WEDNESDAY THROUGH SUNDAY
FAIRLY POTENT CLIPPER SYSTEM WILL BE SLIDING SOUTHEAST ACROSS THE
DAKOTAS WEDNESDAY INTO WEDNESDAY NIGHT. MODELS IN A BIT BETTER
AGREEMENT ON THE TRACK OF THE LOW AND THERMAL PROFILES. HAVE
THEREFORE INCREASED POPS A BIT FROM INHERITED GUIDANCE...MAINLY
ACROSS WESTERN CWA. RATHER MILD AIR MOVES IN WITH THIS SYSTEM SO
PRECIP MAY VERY WELL BE ALL RAIN ACROSS THE WESTERN HALF OF THE
CWA. AS THE COLD FRONT DROPS SOUTH THROUGH THE AREA WEDNESDAY
NIGHT PRECIP EXPECTED TO CHANGE OVER TO ALL SNOW. MODELS
INDICATING A BAND OF ACCUMULATING SNOWFALL SETTING UP SOMEWHERE
ACROSS THE CWA WEDNESDAY NIGHT...WHICH COULD ADD UP TO A COUPLE
INCHES. ANOTHER SYSTEM SLIDING SOUTH THURSDAY INTO THURSDAY
EVENING WILL BRING ANOTHER CHANCE FOR SNOWFALL. COLDER AIR
ASSOCIATED WITH THIS WAVE SO EXPECTING PRIMARILY SNOWFALL WITH
THIS SYSTEM. MODELS NOT GIVING MUCH QPF WITH THIS WAVE DUE TO LACK
OF FORCING...BUT REGARDLESS...STILL LOOKS LIKE A CHANCE FOR LIGHT
SNOWFALL WITH GUSTY NORTHWEST WINDS. MODELS ARE SHOWING A MUCH
STRONGER SYSTEM FOR NEXT WEEKEND BUT MANY DIFFERENCES IN MODELS AS
EXPECTED BEING THIS IS STILL A WEEK AWAY. BASICALLY LEFT GUIDANCE
POPS IN THE GRIDS FOR THIS SYSTEM UNTIL BETTER AGREEMENT IS
REACHED IN THE COMING DAYS.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR MID AND HIGH LEVEL CLOUDS WILL LOWER AND BECOME MVFR/IFR
CEILINGS THROUGH THE NIGHT AS STRONG LIFT FROM A SHORT WAVE
TROUGH MOVES IN. EXPECT WIDESPREAD SNOW TO DEVELOP FROM SOUTHWEST
TO NORTHEAST ACROSS THE REGION. THIS SNOW IS EXPECTED TO AFFECT
ALL TERMINALS WITH VISIBILITIES DOWN TO A HALF MILE AT TIMES. THE
SNOW IS EXPECTED TO CONTINUE THROUGH MUCH OF MONDAY ALONG WITH
IFR/MVFR CEILINGS. THE SNOW WILL END FROM LATE AFTERNOON INTO EARLY
EVENING WITH SKIES CLEARING AT MBG AND PIR IN THE EVENING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY FROM 3 AM TO NOON CST MONDAY FOR BUFFALO-
CAMPBELL-EDMUNDS-FAULK-HAND-HUGHES-HYDE-JONES-LYMAN-
MCPHERSON-POTTER-SULLY-WALWORTH.
WINTER WEATHER ADVISORY FROM 6 AM TO 6 PM CST MONDAY FOR BROWN-
CLARK-CODINGTON-DAY-DEUEL-GRANT-HAMLIN-MARSHALL-ROBERTS-
SPINK.
MN...WINTER WEATHER ADVISORY FROM 6 AM TO 6 PM CST MONDAY FOR BIG
STONE-TRAVERSE.
&&
$$
UPDATE...MOHR
SHORT TERM...CHURCH
LONG TERM...TMT
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1110 PM MST TUE FEB 21 2012
.UPDATE...
OBS CONTINUE TO SHOW WINDS INCREASING AT THE AIR FORCE ACADEMY.
NEW RUC GUIDANCE IS INDICATING WINDS WILL LIKELY KEEP UP AT HIGH
WIND CRITERIA OVER THE EAST SLOPES OF THE PIKES PEAK REGION AND C
MTNS THROUGH TOMORROW MORNING. FOR THIS REASON HAVE DECIDED TO
ISSUE A HIGH WIND WARNING THROUGH ABOUT 15Z TOMORROW. /HODANISH
&&
.PREV DISCUSSION... /ISSUED 954 PM MST TUE FEB 21 2012/
UPDATE...
A COUPLE OF THE USAFA AWOS SENSORS ARE INDICATING WINDS REACHING
MARGINAL HIGH WIND CRITERIA OVER THE LAST HOUR OR SO. SOUNDINGS
INDICATE THESE STRONG WINDS WILL LAST UNTIL ABOUT MIDNIGHT AND
WILL ONLY SLOWLY WEAKEN AS THE REVERSE SHEAR DISSIPATES. FOR THIS
REASON I DO NOT PLAN ON ISSUING ANY HIGH WIND HILITES FOR THE
RAMPART RANGE REGION AT THIS TIME.
AVIATION...
VFR CONDITIONS EXPECTED AT ALL 3 TAF SITES NEXT 24H. GUSTY WEST
WINDS WILL BE POSSIBLE AT KPUB NEXT 24H.
WINDS SHOULD STAY LIGHT AT KCOS...BUT STRONG GUSTY SFC WINDS WILL
BE NOTED JUST WEST OF KCOS DURING THE NEXT 24H.
PREV DISCUSSION... /ISSUED 758 PM MST TUE FEB 21 2012/
UPDATE...
MAIN CHANGE WAS TO ISSUE A FIRE WX WATCH FOR TOMORROW FOR THE
PLAINS...AND HAVE DISCUSSED THIS IN MORE DETAIL IN THE FIRE
WEATHER SEGMENT BELOW.
AFTER LOOKING AT THE 00Z NAM ALONG WITH OTHER SHORT TERM GUIDANCE
PRODUCTS...HAVE DECIDED TO NOT ISSUE ANY HIGH WIND HILITES FOR
THE PIKES PEAK REGION. IT WILL BE WINDY...ESPECIALLY IMMEDIATELY
EAST AND SOUTHEAST OF THE PIKES PEAK MASIF...BUT I DO NOT EXPECT
WE WILL SEE WIDESPREAD GUSTS REACHING CRITERIA. /34
FIRE WEATHER...
HAVE ISSUED A FIRE WX WATCH FOR ALL OF THE PLAINS EXCEPT N EL PASO
COUNTY. IT WILL BE BREEZY TO WINDY ACROSS THE REGION TOMORROW AND
RH VALUES AT MANY LOCATIONS WILL BE REACHING CRITERIA. PUEBLO
DISPATCH UPDATED THE FUELS PAGE AND QUITE A FEW COUNTIES ON THE
PLAINS ARE NOW CRITICAL.
THE STRONGEST WINDS ACROSS S EL PASO COUNTY WILL BE IN THE
IMMEDIATE VICINITY OF PIKES PEAK. MANY AREAS EAST OF I-25 IN
SOUTHERN EL PASO COUNTY WILL HAVE LIGHT WINDS TOMORROW.
PREV DISCUSSION... /ISSUED 253 PM MST TUE FEB 21 2012/
SHORT TERM...
(TONIGHT AND WEDNESDAY)
WINDY!!...
CURRENTLY...THE UPPER LEVEL PATTERN CONSISTS OF A LONGWAVE TROUGH
OVER THE CENTRAL CONUS AND HIGH PRESSURE OFF THE WEST COAST. THIS
HAS PUT COLORADO UNDER STRONG NORTHWESTERLY FLOW. OROGRAPHIC
UPSLOPE HAS LED TO LIGHT SNOW FOR THE CENTRAL MOUNTAINS. OTHERWISE
BREEZY CONDITIONS AND DRY WEATHER HAVE SPREAD ACROSS THE REGION.
WINDS ARE CURRENTLY AVERAGING 25 TO 40 MPH FOR MANY
LOCATIONS...ESPECIALLY THE HIGHER ELEVATIONS AND ALONG AND WEST OF
I-25. TEMPERATURES HAVE WARMED THIS AFTERNOON INTO THE UPPER 50S TO
LOWER 60S FOR THE PLAINS.
TONIGHT...STRONG NORTHWESTERLY FLOW WILL CONTINUE ACROSS THE STATE
WITH CONTINUED LIGHT SNOW FOR THE CENTRAL MOUNTAINS. SNOW
ACCUMULATIONS WILL BE MINOR WITH AN INCH OR TWO OVER THE WEST FACING
PEAKS. DRY CONDITIONS WILL PREVAIL FOR THE REST OF THE CWA. THE
MAIN CONCERN WILL BE THE POTENTIAL FOR STRONG WINDS. HIGH-RES
MODELS ARE INDICATING THE POTENTIAL FOR DOWNSLOPE...PRIMARILY ACROSS
THE FRONT RANGE NORTH OF THE PALMER DIVIDE. HOWEVER AREAS OVER
TELLER COUNTY AND WESTERN EL PASO COUNTY WILL LIKELY SEE A PERIOD OF
STRONG WINDS TONIGHT. WINDS GUSTING TO NEAR 70 MPH WILL BE POSSIBLE
OVER THE HIGHER ELEVATIONS...WITH GUSTS IN EXCESS OF 50 MPH POSSIBLE
WEST OF I-25 OVER WESTERN EL PASO COUNTY. A FEW AREAS PRONE TO
STRONG GUSTS COULD SEE AN OCCASIONAL GUST TO HIGH WIND CRITERIA.
WEDNESDAY...SEVERAL THINGS TO TALK ABOUT. STRONG NORTHWESTERLY FLOW
WILL CONTINUE ALOFT WITH CONTINUED LIGHT CENTRAL MOUNTAIN SNOW. A
COMBINATION OF MIXING AND LEE TROUGH WILL HELP BRING THE STRONG
WINDS ALOFT DOWN. WIDESPREAD GUSTY WINDS ARE EXPECTED WITH MANY
AREAS ACROSS THE PLAINS SEEING GUSTS IN EXCESS OF 30 MPH. HIGHER
ELEVATIONS AND THE ADJACENT PLAINS WEST OF I-25 WILL SEE THE
STRONGEST WINDS THROUGHOUT THE DAY. WITH THE STRONG
MIXING...TEMPERATURES ARE FORECAST TO RISE INTO THE UPPER 60S TO
LOWER 70S FOR THE PLAINS. HUMIDITY VALUES ARE EXPECTED TO REMAIN
LOW...WITH VALUES UNDER 15 PERCENT FOR SOUTHERN PORTIONS OF THE
PLAINS. THE COMBINATION OF STRONG WINDS AND LOW HUMIDITY VALUES
WILL PRODUCE HAZARDOUS FIRE WEATHER CONDITIONS...AND CAUTION IS
ADVISED FOR ANY OUTDOOR FLAMES. 88
LONG TERM...
(WEDNESDAY NIGHT THROUGH TUESDAY)
AN UPR TROF WL DROP SOUTH INTO THE STATE WED NIGHT AND
THU...BRINGING COLDER AIR TO THE FORECAST AREA...AND IT LOOKS A
BIT WINDY OVR THE MTS AND SOME OF THE HIGH VALLEYS. WED NIGHT
THERE SHOULD BE SOME SNOW OVER THE CENTRAL CO MTS. THU MORNING
BOTH THE NAM AND THE GFS SHOW SOME PCPN DEVELOPING AND MOVING
SOUTH OVR THE PALMER DVD. THE NAM IS A LITTLE FASTER BRING PCPN TO
THAT AREA THAN THE GFS. WITH SFC HIGH PRESSURE BUILDING INTO THE
SERN PLAINS THRU MORNING...THE LOW LEVEL FLOW BECOMES EASTERLY AND
THE GFS AND NAM MOVE THE FOCUS OF LIGHT PCPN SOUTHWARD TO SRN EL
PASO AND PUEBLO COUNTIES AND UP AGAINST THE WET MTS FOR THE
AFTERNOON HOURS...WHILE THE SFC WINDS BECOME MORE NORTHERLY OVR
MOST OF EL PASO COUNTY AND MOST OF THE FAR SERN PLAINS. BOTH
MODELS HAVE LITTLE QFP ASSOCIATED WITH THIS SYSTEM FOR ERN AREAS.
PCPN DOES CONTINUE OVR THE CENTRAL MTS THRU THU...SNOW
ACCUMULATIONS FOR WED NIGHT THRU THU IS EXPECTED TO GENERALLY BE
3-6 INCHES. RIGHT NOW IT IS LOOKING LIKE HIGHS ON THU SHOULD BE
JUST A LITTLE BELOW NORMAL OVR THE SERN PLAINS AND AROUND NORMAL
FOR THE SAN LUIS VALLEY. THU EVENING THE PCPN IS EXPECTED TO SHIFT
SOUTH TO LAS ANIMAS COUNTY.
IT STILL LOOKS LIKE IT COULD BE FAIRLY WINDY OVR THE HYR
ELEVATIONS THU NIGHT...BUT THEN ON FRI THE GRADIENT OVR THE AREA
STARTS TO DECREASE AS A RIDGE STARTS BUILDING INTO THE AREA. DRY
WX IS THEN EXPECTED FOR FRI WITH AROUND NORMAL TEMPS. SAT THE FLOW
BECOMES MORE WESTERLY AGAIN AS A NEW UPR TROF MOVES INTO THE NRN
U.S. ROCKIES. THE WX WL BE DRY AND TEMPS WELL ABOVE NORMAL. THE UPR
TROF THEN MOVES ACRS THE AREA SAT NIGHT AND SUN MORNING...BRINGING
CHANCES FOR SNOW TO THE CONTDVD AGAIN...AND PROBABLY A LITTLE TO
THE ERN MTS AS WELL AND MAYBE EVEN SOME LIGHT PCPN TO THE LOWER
ELEVATIONS. THAT SYSTEM EXITS THE AREA SUN NIGHT AND THEN
GENERALLY DRY WESTERLY FLOW IS EXPECTED FOR MON. ANOTHER UPR TROF
IS THEN FORECAST TO MOVE OVR THE AREA ON TUESDAY...BRINGING
ANOTHER CHANCE FOR PCPN TO MUCH OF THE AREA.
AVIATION...
VFR CONDITIONS THROUGH THE NEXT 24 HOURS. WINDS CONTINUE TO GUST AT
KPUB AND KCOS WITH THE STRONGEST WESTERLIES AT KPUB. WINDS SHOULD
DIMINISH THROUGH THE AFTERNOON HOURS. THE POTENTIAL FOR DOWNSLOPE
WINDS OFF THE RAMPART RANGE CONTINUES FOR TONIGHT WITH STRONG WIND
GUSTS AT KCOS POSSIBLE BY AROUND 10Z. PRIOR TO THE ONSET OF STRONG
WINDS...LLWS CAN BE EXPECTED. WINDS IN EXCESS OF 35 KTS WILL BE
POSSIBLE THROUGH THE EARLY MORNING HOURS. WINDS ARE FORECAST TO
INCREASE AT KPUB DURING THE MID MORNING HOURS WITH GUSTS THROUGHOUT
THE DAY. 88
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH WEDNESDAY AFTERNOON FOR COZ227>237.
HIGH WIND WARNING UNTIL 8 AM MST WEDNESDAY FOR COZ060-061-081-
082-084-085.
&&
$$
34/34
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
400 AM EST Wed Feb 22 2012
.SYNOPSIS...
08Z water vapor and H4 RUC analysis shows northern stream flow
arriving over the Pacific Northwest/British Columbia coast before
carving out a broad longwave trough over much of the CONUS to the
east of the continental divide. A weak impulse embedded within this
flow over the southern Plains will quickly slide eastward toward the
forecast area by this evening. Southern stream flow extends from the
west coast of Mexico eastward over the northern Gulf/Gulf coastal
region, and continues to pump abundant mid/upper level moisture
overhead. One other feature of note, is a cutoff upper low spinning
over the Baja region of Mexico. This energy has been a real "thorn
in our side" the past couple of days as global models have had
significant difficulty with its evolution. Will discuss this further
below.
At the surface, ridge axis runs from the central FL peninsula
northward to our forecast area. Light winds and a slow low level
moisture return on the western periphery of the ridge is resulting
in area of fog this morning. Temperatures are generally in the upper
40s to middle 50s, and with expanding areas of fog/lower clouds,
don`t anticipate much further of a temperature drop.
&&
.SHORT TERM (Today through Friday)...
Today, Weather will start out quiet, however changes will take place
by the end of the day. Surface high pressure currently in place will
shift south and east with time in response to adjusting mass fields
ahead of the weak approaching northern stream impulse. Ahead of this
impulse, low/mid level SW flow will increase allowing a broad WAA
regime to expand across the area. GFS/ECMWF show increasing low
level ascent/upglide along the 295-310K surfaces overtaking the
area, with the deepest ascent/moisture fields over the southern/SE
zones. Always a tough call in these scenarios as to just where the
most numerous showers will end up. Generally speaking, NWP guidance
is often too slow in the development of upglide/WAA precipitation.
Took this into account and allowed showers to develop into the
coastal areas of the FL panhandle around noon, and then quickly
expand north and east through the afternoon. Based on general NWP
agreement in where the deeper lift will occur, have highest rain
chances 60-80% south of a line from Dothan to Moultrie to Valdosta.
Still expect at least some shower activity north of this line based
on latest hi-res ensemble CAM guidance, however confidence in the
overall coverage is lower, and will take PoPs down to 40-50%. In
addition, will add isolated thunderstorms to the grids due to
showalter indices between -2 to 0. Not out of the question that a
few of these storms may be on the strong side (wind gust the main
threat) as strengthening flow will result in deep layer shear
profiles supportive of organized convection.
Tonight, Weak synoptic forcing and best upglide will shift into the
eastern Big Bend/Suwannee River Valley by later this evening, and
then exit our region around midnight. Looks like there may be just
enough forcing left behind to support isolated showers into the
early morning hours, however doesn`t look too impressive and will
allow Pops to drop below 20% for all zones. SW low level flow off
the Gulf will keep our temps warm with lows in the mid/upper
50s inland and lower 60s at the coast.
Thursday, Upper level pattern will begin to amplify as shortwave
energy drops down the backside of the main northern stream trough.
Associated surface low pressure will push east from the Central
Plains toward the Ohio Valley, with a trailing cold front down along
the MS valley. Deep southerly low level flow will give us a rather
warm and humid day for the end of February. Good diurnal mixing and
850mb temps around 14-15C will allow many inland locations to reach
the mid/upper 70s (perhaps a few spots touching 80). Along the
immediate coast temps will be a bit cooler with the flow off the
shelf waters. Model agreement in several hundred J/KG of mixed layer
CAPE during the afternoon argued for a slight rain chances (a
few isolated "pop-up" showers/storms away from the coast).
Friday,
Threat for severe storms is not gone, however the overall threat
has lowered from 24 hours ago. Global guidance members now all agree
that the northern stream trough will not dig enough to grab the
cutoff energy over the Mexican Baja and eject it eastward fast
enough for phasing. This is good news in general as resulting
synoptic lift and kinematic fields appear not as impressive. As the
upper trough moves toward the eastern CONUS, the associated surface
cold front will still approach and cross our region, with a good
chance for a round of showers and storms. GFS has a faster frontal
passage and argues for the best rain chances late Thursday night
into Friday, while the ECMWF suggest during the day Friday/Friday
night. As mentioned above, although the threat has lowered, can`t
let our guard down in term of severe potential, as sufficient shear
for organized convection is still progged by the global guidance.
Will continue to monitor.
&&
.LONG TERM (Friday Night through next Wednesday)...
Guidance is not in good agreement for much of the extended period.
Much of the discrepancy through the weekend is tied to the evolution
of the cut-off low currently dropping into the Baja region of
Mexico. Guidance has all trended towards a much slower solution as
this feature treks east towards the Gulf of Mexico. However, the 00Z
ECMWF/Canadian have the feature picked up by the northern stream
flow Friday night, while the GFS is 12+ hours slower. The main
impact of this slower motion is to develop a more substantial sfc
reflection over the SW Gulf late Saturday which helps push an large
area of overrunning precip into the forecast are on Sunday. The
ECMWF/Canadian solution keeps the area dry for this period. HPC
prefers to quicker solution, and will follow suit with a dry
forecast for Sunday.
Guidance is in somewhat better agreement for Monday into Tuesday as
return flow increases ahead of a deepening trough over the central
states. This should allow for at least scattered PoPs for the region
as a front moves into the southeastern states. Guidance then
diverges substantially with the evolution of the large scale flow
with a multitude of solutions. Guidance seems to generally indicate
some chance for precip Tuesday into Wednesday, so have broadbrushed
slight chance PoPs through the end of the period.
&&
.MARINE...
Surface high pressure will settle south of the forecast waters
through the day allowing a strengthening flow out of the southwest.
Expect cautionary level wind to develop by early this evening and
generally persist through Thursday. A period of advisory level winds
and seas will be possible Thursday night into Friday ahead of an
approaching cold front. Advisory level winds will then shift to the
northwest and north in the wake of this front later Friday into
Friday night.
&&
.AVIATION (Through 06Z Thursday)...
Potential for dense fog remains the big question for the remainder
of the overnight hours. Satellite and surface obs show lowering CIGS
and Vis across FL Panhandle/SE Alabama. Expect these conditions to
spread east overnight. High clouds streaming across the region may
prevent prolonged periods of sub-1/4SM vis. Cigs will be slow to
lift after sunrise with VFR conditions expected only briefly during
the early afternoon. Thereafter, low clouds will move back in by
early evening. Showers will likely impact the Florida terminals this
afternoon. There is a small chance for a thunderstorm, although
confidence too low attm to include in TAF.
&&
.FIRE WEATHER...
Low level moisture will remain abundant across the region through
Friday ahead of an approaching front. A drier airmass will move in
during the weekend with RH values dropping into the lower 30s.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 71 59 76 64 72 / 70 40 20 20 70
Panama City 68 61 71 65 68 / 70 30 20 30 60
Dothan 72 57 79 64 67 / 60 20 20 50 60
Albany 71 57 79 65 70 / 40 20 20 40 70
Valdosta 71 60 79 64 74 / 50 50 20 20 60
Cross City 72 61 76 63 76 / 50 60 20 10 50
Apalachicola 67 62 70 65 69 / 70 40 10 20 60
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...None.
GA...None.
FL...None.
GM...None.
&&
$$
Synopsis/Short Term/Marine...Mroczka
Long term/Aviation/Fire Wx...Camp
AREA FORECAST DISCUSSION
NWS DES MOINES IA
316 AM CST WED FEB 22 2012
.SHORT TERM /TODAY/...
TODAYS FORECAST IS RATHER COMPLEX AND IT DOESNT HELP THAT THE
MODELS ARE NOT HANDLING THE FINE DETAILS WELL AT ALL. A PRETTY WEAK
VORT MAX MOVED ACROSS THE FORECAST AREA DURING THE OVERNIGHT AND
THAT WAS ENOUGH TO PRODUCE SOME VERY LIGHT RAIN AND AREAS OF
DRIZZLE. CLEARLY THERE IS MORE MOISTURE IN THE ATMOSPHERE THAN THE
MODELS ARE SUGGESTING. LOOKING UPSTREAM ON WATER VAPOR OVERLAID
WITH RUC 500MB VORTICITY...THERE IS ANOTHER VORT MAX PROGGED TO PUSH
ACROSS THE FORECAST AREA BETWEEN 12 AND 15Z. NAM12 TIME HEIGHT
CROSS SECTIONS SHOW THE WEAK LIFT COMING ACROSS AREA HOWEVER IT
SHOWS SOME DRY LOW LEVEL AIR. HOWEVER...IT DID A POOR JOB WITH
MOISTURE WITH THE LAST VORT MAX SO I HAVE TO BELIEVE IT IS NOT
CAPTURING THE DEPTH OF MOISTURE WELL FOR THIS NEXT SHOT. FOR THAT
REASON I HAVE PUT A SLIGHT CHANCE OF RAIN WITH AREAS OF DRIZZLE
ALONG THE EXPECTED PATH OF THIS NEXT VORT MAX.
TAKING A LOOK AT TEMPS...THEY ARE ALL OVER THE PLACE. IN PART DUE
TO CLOUD COVER AND IN PART DUE TO SOME LOW LEVEL WINDS THAT ARE MORE
SOUTH SOUTHWEST THAN WEST. THE PROBLEM IS THAT TEMPS CURRENTLY ARE
HOVERING RIGHT AT OR JUST BELOW FREEZING. I EXPECT LITTLE TEMP
CHANGE BETWEEN NOW AND 12-13Z OR MAYBE A DROP OF A DEGREE OR TWO.
WITH MOISTURE IN PLACE AND WEAK LIFT AND TEMPS HOVERING AT OR JUST
BELOW FREEZING I HAD TO PUT A MENTION OF FREEZING DRIZZLE IN THE
FORECAST ON THE NORTHERN FRINGE OF THE PATH OF THE NEXT SHOT OF
VORTICITY COMING AT US. I EXPECT THIS ALL TO OCCUR THIS MORNING
YET.
FOR THE REST OF TODAY WE ARE SORT OF IN LIMBO WAITING FOR THE NEXT
SYSTEM TO MOVE IN TONIGHT. I EXPECT TO SEE A FAIR AMOUNT OF MID AND
HIGH LEVEL CLOUD COVER TODAY THEN GRADUALLY MOISTENING UP AS THE
AFTERNOON PROGRESSES. AT THIS POINT I REALLY DON/T SEE MUCH IN THE
WAY OF PRECIP FOR THE AFTERNOON BUT AS MOISTEN UP AHEAD OF THE
SYSTEM TONIGHT...I THINK WE WILL SEE SOME DRIZZLE ACROSS THE AREA.
FOR NOW I JUST HAVE IT ACROSS THE NORTH BUT POTENTIALLY COULD BE
MORE WIDESPREAD THAN THAT. SHOULD BE A FAIRLY MILD DAY AS WE MIX
SOME OF THE WARMER AIR ALOFT DOWN. I WENT A LITTLE AGGRESSIVE ON
THE WARM UP TODAY BUT WE WILL HAVE CLOUD COVER TODAY WHICH WILL
IMPACT THE WARM UP. IF WE HAVE A LOWER CLOUD DECK THAN WHAT I AM
THINKING THEN WE MAY BE TOO WARM. WE WILL NEED TO WATCH THAT.
.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
COMPLICATED FORECAST THIS EXTENDED PERIOD. A NUMBER OF FAST MOVING
WAVES IMPACTING THE REGION OVER THE NEXT 24 HOURS AND LITTLE MODEL
CONSENSUS ON TRACK AND PLACEMENT OF FEATURES. MODELS HAVING A
DIFFICULT TIME RESOLVING THE ENERGY AND THIS WILL MOST LIKELY RESULT
IN FURTHER REFINEMENT IN THE NEXT 1 TO 2 PACKAGES. FIRST WAVE
EXPECTED TO ARRIVE TONIGHT. NAM/GFS CONTINUE TO SHOW A MORE
NORTHERLY SOLUTION OVER NORTHERN IOWA FOR THE FIRST WAVE WHILE THE
GEM/EURO ARE TAKING THE ENERGY FARTHER SOUTH AND ACROSS NORTHERN
MISSOURI. WITH SOME COORDINATION CHALLENGES...HAVE OPTED TO BROAD
BRUSH THE REGION WITH CHANCE POPS...BUT WOULD HAVE PREFERRED TO
FOCUS MORE ON THE SOUTH FOR THE FIRST WAVE. THERMAL PROFILES AND SFC
TEMPERATURES POINT TO MOSTLY LIGHT SNOW NORTH AND A RAIN SNOW MIX
CENTRAL WITH SHOWERS SOUTH HALF. WITH THE SECOND AND STRONGER WAVE
IMPACTING THE AREA ON THURSDAY WHICH DEEPENS AND SLOWS AS IT CROSSES
THE REGION. THE AREA OF WARM AIR ADVECTION ALONG AND AHEAD OF IT IS
ALSO ACCOMPANIED BY AN AREA OF WEAK STABILITY...AND NEGATIVE EPV.
THOUGH IT LOOKS VERY PROBABLE THAT THE PRECIPITATION MAY BE
ACCOMPANIED BY THUNDER...THE LACK OF ANY CONSISTENCY IN TRACK THIS
MORNING MAKES IT DIFFICULT TO PLACE WHERE THIS MIGHT OCCUR. FOR
NOW...HAVE LEFT THE MENTION OUT OF THE FORECAST SO THE AREA CAN BE
BETTER REFINED LATER TODAY. NONE THE LESS...THE AREA WITH GREATER
LIFT IS LIKELY TO SEE SNOW OVERTAKE THE RAIN/SNOW MIX AS CONVECTION
ENHANCES THE PRODUCTION OF SNOW OVER RAIN SHOWERS. CURRENTLY AM
GOING TO GO WITH AN AREA BOUNDED BY JUST SOUTH OF I80 IN THE SOUTH
AND NEAR HIGHWAY 20 IN THE NORTH. WITH THE MIX MOST LIKELY FROM US
30 NORTH...THE HEAVIER SNOWFALL IS MAINLY EXPECTED BETWEEN US 30 AND
US 20 WHERE A BAND OF 1-3 MAY FALL. THIS BEARS WATCHING CLOSELY AND
WILL CAUTION ONCOMING SHIFT THAT FURTHER REFINEMENTS AND DETAIL WILL
BE NEEDED. NO HEADLINES PLANNED RIGHT NOW...AND WILL LET THE NEXT
SHIFT WORK THROUGH THE POSSIBILITY OF HEAVIER SNOW...IF THE NEWER
MODEL RUNS SHOW MORE CONSENSUS. AS THE LOW DEEPENS OVER THE
REGION...A SECONDARY H500 LOW WILL EXTEND BACK INTO CENTRAL IOWA
THURSDAY NIGHT AND LIKELY DROP ANOTHER 1 TO 2 INCHES OF SNOW OVER
THE NORTHEAST THIRD OF THE FORECAST AREA. PLAYING IT CONSERVATIVE
FOR NOW...DUE TO UNCERTAINTY WITH THE MODELS. COLD AIR AND LIGHT
SNOW AND FLURRIES WILL CONTINUE ON FRIDAY WITH LIGHT ACCUMULATIONS
POSSIBLE. BY SATURDAY A RIDGE WILL REPLACE THIS FIRST BATCH OF
ENERGY PRIOR TO THE LARGER SYSTEM APPROACHING FOR SUNDAY/MONDAY.
MODELS CONTINUE TO SHOW LITTLE OVERALL CONSENSUS YET...THOUGH THE
GEM/EURO HAVE SHOWN CONSISTENCY BETWEEN THESE TWO MODELS THE PAST
FEW RUNS. THE GFS IS STILL MUCH DEEPER...EARLIER...AND MAY BE TOO
QUICK TO ADVANCE THE ENERGY EAST AND WIND UP THE LOW. WITH THAT IN
MIND...HAVE BEEN LEANING TOWARD A WARMER SOLUTION FOR SUNDAY WITH
COORDINATION OF SURROUNDING OFFICES AND FAVORING RAIN SHOWERS FOR
NOW. STRONG COLD FRONT AND SNOW CHANCES RETURN SUNDAY NIGHT AS COLD
AIR WRAPS INTO THE SYSTEM. THE REAL SNOW SHOULD FALL WELL NORTHWEST
OF US IN THE DAKOTAS AND MINNESOTA BASED ON ALL THREE MED RANGE
MODELS WHICH ARE NOW BACKING THE LOW NORTHWEST WITH TIME. MUCH
COLDER AIR RETURNS FOR MONDAY AND TUESDAY WITH SOME RECOVERY BY
WEDNESDAY.
&&
.AVIATION DISCUSSION...22/06Z
SEVERAL PIECES OF UPPER LEVEL ENERGY WILL PASS ACROSS IOWA DURING
THE FORECAST PERIOD. POSSIBLE SPRINKLES OR SNOW FLURRIES OVERNIGHT
INTO EARLY WEDNESDAY MORNING WITH BRIEF LOCAL MVFR CIGS POSSIBLE.
THE STRONGEST PIECE OF ENERGY WILL ARRIVE LATE IN THE AFTERNOON AND
EVENING. EXPECT MVFR CIGS AND PRECIPITATION TO AFFECT ALL SITES FOR
THE END OF THE PERIOD. WINDS WILL BE LIGHT TONIGHT BECOMING WESTERLY
DURING THE DAY WEDNESDAY.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...FAB
LONG TERM...REV
AVIATION...DONAVON
AREA FORECAST DISCUSSION
NWS TOPEKA KS
329 AM CST WED FEB 22 2012
.DISCUSSION...
BREEZY SEVERAL DAYS AHEAD...WITH DAILY CHANGES IN TEMPERATURES QUITE
NOTICEABLE. SPECIFICS ON THESE VALUES AND HUMIDITY LEVELS TODAY ARE THE
MAIN CHALLENGES THROUGH THE LATE WEEK.
VERY STRONG JET AGAIN SAMPLED FROM THE BERING SEA AREA EAST INTO
CENTRAL BRITISH COLUMBIA THEN SOUTHEAST INTO WYOMING WITH SPEEDS OF
150-180KT. DEEP UPPER LOW WAS OVER THE WESTERN GREAT LAKES WITH A
FEW SHORTWAVES MOVING THROUGH THE MAIN JET. 0Z 850MB TEMPERATURES
RANGED FROM 1C AT KTOP TO 5C AT KDDC TO 14C AT KAMA. SLIGHTLY HIGHER
MOISTURE THROUGHOUT THE LOWER TROPOSPHERE WAS NOTED AT KLBF IN
COMPARISON TO KTOP. SCATTERED MID AND HIGH CLOUDS WERE MOVING
THROUGH KANSAS WITH TEMPS STILL IN THE UPPER 30S TO MIDDLE 40S AT
08Z.
WEST TO NORTHWEST FLOW TO AGAIN BE QUITE DEEP THROUGH THE DAYTIME
PERIODS...PROMOTING DEEP MIXING AND GUSTY WINDS. SURFACE LOW
PRESSURE WILL ORGANIZE IN THE NORTHERN PLAINS AHEAD OF A SHORTWAVE
TROF...WITH WEST TO SLIGHTLY NORTHWEST WINDS FOR TODAY. TRAJECTORIES
OF ABOVE THE FIRST FEW THOUSAND FEET WILL HAVE A NORTHERLY
COMPONENT...AND THE BETTER WESTERN NEBRASKA-AREA MOISTURE WILL
ADVECT INTO THE AREA...KEEPING DEWPOINTS FROM DROPPING TOO FAR. EVEN
TRIMMING GUIDANCE A FEW DEGREES KEEPS RELATIVE HUMIDITIES IN THE
UPPER 20S TO MIDDLE 30S FOR MOST LOCATIONS. WIND SPEEDS ALSO LOOK
MARGINAL AT BEST FOR RED FLAG CRITERIA...WITH BETTER CLOUD COVER
EXPECTED FOR THE AFTERNOON HELPING TO KEEP PERSISTENT GUSTS IN
CHECK. HAVE INCREASED THE HIGH TEMPERATURE GRADIENT A BIT GIVEN THE
SLIGHT VARIATION IN WEST TO NORTHWEST WINDS FROM SOUTHERN TO
NORTHEAST LOCATIONS. COLD FRONT WITH THE SHORTWAVE TO ARRIVE LATE
TONIGHT...WITH MID LEVEL BAROCLINICITY INCREASING AS THE SHORTWAVE
NEARS THURSDAY. STILL SOMEWHAT DRY MID-LOW LEVELS WILL KEEP PRECIP
AT BAY...WITH STRONG NORTHWEST WINDS BRINGING 850MB TEMPS SOME
10-12C COOLER THAN TODAY. DEEP-LAYER WINDS DONT APPEAR STRONG ENOUGH
FOR ADVISORY SPEEDS HOWEVER. AFTERNOON TEMPERATURES MAY BE RATHER
STEADY AND HAVE ADVERTISED SUCH IN THE FORECAST. 500MB TEMPS DROP TO
NEAR -34C BY THURSDAY NIGHT...WITH VERY DEEP MIXING PROGGED BY BOTH
GFS AND NAM FRIDAY AFTERNOON. SUSTAINED SPEEDS SHOULD REMAIN SHORT
OF ADVISORY LEVELS...BUT COULD SEE GUSTS BE A PROBLEM WITH GOOD
DOWNWARD MOTION AND LOTS OF SUN.
TRENDED DOWN LOWS FRIDAY NIGHT WITH WINDS FINALLY WEAKENING AND
UPPER RIDGE NEARING. SOUTH WINDS INCREASE FOR SATURDAY AND LIKELY
INTO MUCH OF SUNDAY AS THE NEXT UPPER TROF NEARS. SOME DIFFERENCES
TAKE SHAPE WITH FAST THIS SYSTEM WILL BE...BUT SOUTHWEST WINDS
SHOULD BE ADEQUATE TO PUSH HIGHS BACK INTO THE UPPER 50S FOR AT
LEAST SOUTHERN AND EASTERN AREAS BEFORE THE FRONT WOULD ARRIVE ON
THE FASTER GFS. MOISTURE MAY BE DEEP ENOUGH FOR LIGHT PRECIPITATION
SUNDAY NIGHT. KEPT CHANCE POPS IN FOR TUESDAY...BUT CONFIDENCE NOT
HIGH AS DISCREPANCIES INCREASE. AIRMASS COMING IN BEHIND THE
SUNDAY/SUNDAY NIGHT SYSTEM IS SOURCED FROM NORTHWEST CANADA...WITH
HIGHS AT LEAST SEVERAL DEGREES BELOW NORMAL A GOOD BET.
65
&&
.AVIATION...
THE 00Z NAM AND 03Z RUC FORECAST SOUNDINGS CONTINUE TO SHOW A STRONG
NOCTURNAL INVERSION OVERNIGHT AS LOW LEVEL WINDS INCREASE TO AROUND
40KTS. BECAUSE OF THIS WILL INCLUDE A MENTION OF WIND SHEER AROUND
1000FT FOR THE EARLY MORNING. BY WEDNESDAY AFTERNOON THE BOUNDARY
LAYER IS EXPECTED TO MIX OUT WITH DRY ADIABATIC LAPSE RATES. THIS
COULD ENCOURAGE SOME GUSTS DURING THE AFTERNOON. OTHERWISE DRY LOW
LEVELS OF THE ATMOSPHERE WILL ALLOW VFR CONDITIONS TO PREVAIL.
WOLTERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1105 PM CST TUE FEB 21 2012
...AVIATION UPDATE...
.DISCUSSION...
SEE PREV DISCUSSION.
&&
.AVIATION...
THE 00Z NAM AND 03Z RUC FORECAST SOUNDINGS CONTINUE TO SHOW A STRONG
NOCTURNAL INVERSION OVERNIGHT AS LOW LEVEL WINDS INCREASE TO AROUND
40KTS. BECAUSE OF THIS WILL INCLUDE A MENTION OF WIND SHEER AROUND
1000FT FOR THE EARLY MORNING. BY WEDNESDAY AFTERNOON THE BOUNDARY
LAYER IS EXPECTED TO MIX OUT WITH DRY ADIABATIC LAPSE RATES. THIS
COULD ENCOURAGE SOME GUSTS DURING THE AFTERNOON. OTHERWISE DRY LOW
LEVELS OF THE ATMOSPHERE WILL ALLOW VFR CONDITIONS TO PREVAIL.
WOLTERS
&&
.PREV DISCUSSION... /334 PM CST TUE FEB 21 2012/
WESTERLY FLOW IN THE MID LEVELS WILL CONTINUE THROUGH THE PERIOD. A
SHORTWAVE WILL DROP SOUTHWEST OUT OF THE PACIFIC NORTHWEST LATE
TONIGHT WITH INCREASE IN MID LEVEL MOISTURE SO EXPECT A MID CLOUD
DECK TO MOVE OVER AFTER MIDNIGHT THEN EXIT DURING THE MORNING HOURS
ON TUESDAY. AS ANOTHER WAVE MOVES ACROSS THE NORTHERN PLAINS ON
TUESDAY MORE CLOUDS WILL MOVE INTO THE FAR NORTHERN COUNTIES IN THE
AFTERNOON NEAR THE NEBRASKA BORDER.
TONIGHT THE WINDS WILL DROP OFF AFTER SUNSET AS THE WINDS DECOUPLE
IN THE BOUNDARY LAYER. THIS WILL ALLOW TEMPERATURES TO COOL INTO THE
LOW TO MID 30S.
ON TUESDAY...THE COMBINATION OF WESTERLY DOWNSLOPE FLOW...ABUNDANT
SUNSHINE AND MIXING DOWN FROM 800 MB WILL YIELD HIGHS IN THE LOW TO
MID 60S FOR MUCH OF THE AREA. WEST WINDS WILL GUST OVER 20 MPH IN
THE AFTERNOON.
53
NEXT SHORTWAVE TROUGH MOVING ACROSS THE NORTHERN PLAINS WEDNESDAY
NIGHT/THURSDAY WILL FOCUS PRECIP TO THE NORTH OF THE AREA WITH
STILL A DRY FCST FOR THIS PERIOD. HOWEVER...AFTER WESTERLY WINDS
MOST OF THE NIGHT...A FRONT WILL BEGIN TO TRAVERSE THE CWA LATE IN
THE NIGHT. THE TIMING OF THE FRONT WILL LIKELY BE TOO LATE TO HAVE
A LOT OF IMPACT ON LOW TEMPS...EXCEPT MAYBE THE FAR NORTH WHERE A
FEW READINGS IN THE MIDDLE 30S ARE EXPECTED. ELSEWHERE...TEMPS
EXPECTED TO REMAIN WELL ABOVE NORMAL WITH LOWS SOUTH OF I 70
GENERALLY 40 TO 43 DEGREES. THE AFFECTS OF THE COLDER AIR MOVING
INTO THE CWA BEHIND THE FRONT WILL BE FELT MORE DURING THE DAY
THURSDAY AS HIGH TEMPS TOP OUT IN THE UPPER 40S AND LOWER 50S...OR
ABOUT 10 TO 15 DEGREES COOLER THAN WEDNESDAY ALONG WITH A BLUSTERY
NORTHWEST.
THE COOLEST HIGHS STILL LOOK TO BE ON FRIDAY WHERE THE COOLER LOWS
IN THE 20S TO AROUND 30 WILL HELP TO LIMIT THE DAYTIME HIGHS TO THE
40S. THE UPPER LEVEL PATTERN INTO THE WEEKEND STILL SHOWS THE UPPER
LEVEL SHORTWAVE TROUGH OVER THE GREAT LAKES MOVING OFF THE EAST
COAST WITH ANOTHER STRONG UPPER TROUGH ADVANCING FROM THE PACIFIC
NORTHWEST AND INTO THE NORTHERN PLAINS BY SUNDAY. WARM AIR ADVECTION
AHEAD OF THIS SYSTEM OVER THE WEEKEND SHOULD PUSH HIGHS INTO THE
LOWER 50S IN MANY AREAS BEFORE THE NORTHERN PLAINS WAVE PUSHES
ANOTHER COLD FRONT ACROSS THE CWA SUNDAY NIGHT. THIS WILL PROVIDE
THE NEXT CHANCE FOR RAIN OR POSSIBLY SOME SNOW SUNDAY NIGHT AS THE
COLDER AIR OVERSPREADS THE AREA BEHIND THE FRONT.
THERE MAY THEN BE A BRIEF BREAK IN PRECIP CHANCES DURING THE DAY ON
MONDAY BEFORE ANOTHER SYSTEM APPROACHES THE CENTRAL PLAINS FROM THE
ROCKIES LATER MONDAY NIGHT INTO TUESDAY. IF THIS SCENARIO
HAPPENS...MORE COLD AIR WOULD ALREADY BE IN PLACE AHEAD OF IT AND
THEREFORE SNOW CHANCES WOULD BE A LITTLE HIGHER. IT IS DIFFICULT
THIS FAR OUT IN THIS PATTERN TO GO WITH AN ALL SNOW FORECAST FOR AN
EXTENDED PERIOD OF TIME. WILL GO WITH A LIGHT SNOW/RAIN SNOW MIX
MONDAY NIGHT AND TUESDAY FOR NOW WITH HIGHS TUESDAY IN THE 30S. 63
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS JACKSON KY
1238 AM EST WED FEB 22 2012
.UPDATE...
ISSUED AT 1238 AM EST WED FEB 22 2012
MADE SOME MINOR TWEAKS TO TEMPERATURES AND DEWPOINTS. ALSO DECREASED
SKY COVER FOR THE REST OF THE NIGHT WITH CLOUDS PUSHING OFF TO THE
NORTHEAST. SOME MORE HIGHS CLOUDS WILL SPREAD IN LATE TONIGHT...BUT
SHOULD BE MORE SCATTERED IN NATURE. I DID SLOW DOWN THE ARRIVAL OF
PRECIPITATION INTO OUR AREA TOMORROW MORNING GIVEN THE LATEST HRRR
AND RUC SHOWING NO MOISTURE IN OUR VICINITY UNTIL AT LEAST 18Z. GOING
TO HAVE TO TAKE A GOOD LOOK AT TOMORROW AFTERNOON BECAUSE INSTABILITY
IS LOOKING A BIT BETTER AND WITH TREMENDOUS SHEAR...WE COULD HAVE A
DAMAGING WIND THREAT. NEXT UPDATE WILL TRY TO CAPTURE MORE OF THE
CURRENT THINKING.
UPDATE ISSUED AT 947 PM EST TUE FEB 21 2012
UPDATED THE ZONES AND GRIDDED FORECASTS TO REFLECT CURRENT CONDITIONS
AND MODEL TRENDS. THE REST OF THE FORECAST IS ON TRACK. ANY CHANGES
WERE REALLY QUITE MINOR.
UPDATE ISSUED AT 633 PM EST TUE FEB 21 2012
UPDATED THE ZONES AND GRIDS TO DECREASE THE CLOUDS QUICKER AND TO
ADJUST THE TEMPERATURE...WINDS...AND DEWPOINTS TO REFLECT CURRENT
CONDITIONS AND MODEL TRENDS. THE REST OF THE FORECAST IS ON TRACK AND
THE NEXT UPDATE WILL BE SENT OUT BY 10 PM.
&&
.SHORT TERM...(TONIGHT THROUGH THURSDAY)
ISSUED AT 347 PM EST TUE FEB 21 2012
WARM AIR ADVECTION WILL PERSIST THROUGH THE PERIOD...WITH TEMPS
CONTINUING TO CLIMB. GREATER LOW LEVEL MOISTURE WILL FINALLY BE
ADVECTED INTO OUR AREA ON WEDNESDAY...ESPECIALLY IN SOUTHERN AND
EASTERN COUNTIES. COMBINED WITH FORECAST COOLING IN THE MID AND
UPPER LEVELS...THE RESULTING STEEP LAPSE RATES AND INSTABILITY SHOULD
RESULT IN AT LEAST SCATTERED SHOWERS. CAN NOT RULE OUT A FEW
LIGHTNING STRIKES EITHER. WITH STRONG ENVIRONMENTAL WINDS
ALOFT...THIS POSES A VERY SMALL RISK OF HIGH WINDS IF CONVECTION CAN
MIX THESE WINDS DOWN. ACTIVITY MAY PERSIST INTO WEDNESDAY NIGHT IN
THE WARM AIR ADVECTION REGIME...BUT WARMING ALOFT LATE WEDNESDAY
NIGHT AND THURSDAY WOULD NIX CONVECTION.
WILL LOOK FOR SOME RIDGE/VALLEY DIFFERENCES AGAIN EACH NIGHT.
HOWEVER...THINK THAT WINDS WILL WORK TO KEEP MANY OF THE NORMALLY
COLDER LOCATIONS FROM DECOUPLING COMPLETELY...WHICH WOULD RESTRICT
THE COLDEST TEMPERATURES TO THE DEEPEST VALLEYS IN THE EAST AND
SOUTHEAST.
.LONG TERM.../THURSDAY NIGHT THROUGH TUESDAY/
THE MODEL CONSENSUS GENERALLY HAS RIDGING CENTERED NEAR HISPANIOLA
AND RIDGING OFF THE WEST COAST OF THE US WITH TROUGHING IN BETWEEN
TO START THE PERIOD. THIS TROUGH WILL GRADUALLY SHIFT NORTH AND
NORTHEAST THROUGH SAT...WITH THE AXIS OF THIS TROUGH PASSING EAST
FRI NIGHT OR SAT. AS THE TROUGH APPROACHES...A RATHER POTENT SFC LOW
IS EXPECTED TO TRACK THROUGH THE OH VALLEY REGION ON THU NIGHT INTO
EARLY ON FRI. THIS SCENARIO WOULD ALSO SEND A COLD FRONT ACROSS THE
AREA LATE THU NIGHT OR FRI. THE DEEPER 20/00Z ECMWF AND 20/12Z ECMWF
LEAD TO A WETTER AND SOMEWHAT MORE DYNAMIC SOLUTION THAN RECENT GFS
RUNS. RIDGING WILL THEN WORK INTO THE REGION OVER THE WEEKEND...BUT
WILL NOT LINGER ALL THAT LONG AND IS PROGGED BY THE 20/00Z ECMWF AND
20/12Z ECMWF TO SHIFT EAST OF THE AREA BY LATE SUN NIGHT...WHILE
THIS OCCURS A BIT FASTER IN THE LESS AMPLIFIED 12Z GFS. OVERALL...
UNCERTAINTY INCREASES TO VERY LOW CONFIDENCE FROM LATE SUN ON...AS
THE RECENT GFS RUNS ARE NEARLY 24 HOURS FASTER BRINGING A TROUGH AND
ASSOCIATED SFC SYSTEM EAST INTO THE PLAINS AND ON INTO THE EASTERN
CONUS FROM THE ROCKIES AND WESTERN US MOUNTAINS COMPARED TO THE
ECMWF. SOME BRIEF RIDGING COULD BUILD INTO THE REGION BY THE END OF
THE PERIOD DEPENDING ON TIMING.
WITH TIMING UNCERTAINTIES A BLEND OF MODEL CONSENSUS AND THE
PREVIOUS FORECAST IS GENERALLY THE BEST APPROACH AT THIS TIME.
EXCEPT FOR TIMING OF EITHER GENERALLY AT NIGHT OR EARLY MORNING...
SOME THUNDERSTORMS...POSSIBLY STRONG...MIGHT BE A CONCERN FOR THU
NIGHT INTO EARLY ON FRI. THE RECENT SPC DAY 3 OUTLOOK BRUSHES THE
SOUTHWEST CWA WITH A SLIGHT RISK OF SEVERE THUNDERSTORMS. INSTABILITY
MAY BE RATHER LIMITED ESPECIALLY IN AREAS FURTHER TO THE NORTH...BUT
AT LEAST SOME GUSTY SHOWERS OR ISOLATED THUNDER SEEM PROBABLE WITH
OR PRECEDING THE COLD FRONT...WITH UNCERTAINTY IN THE EXACT TIMING.
OVERALL...RECENT MODEL RUNS ARE BRINGING INCREASING CONFIDENCE IN
MEASURABLE RAINFALL AT SOME POINT WITH THE FRONT. HAVE OPTED TO ADD
ISOLATED THUNDER TO THE GRIDS FOR THU NIGHT AT THIS POINT AND ADD
THUNDER CHANCES TO THE HWO. ALTHOUGH THE HIGHEST POPS WITH THIS
SYSTEM WILL BE WITH THE COLD FRONT...WEAKER SHORTWAVES PASSING BY IN
THE FLOW AS LATE AS FRI NIGHT AND EARLY SAT WILL BRING A CONTINUED
CHANCE FOR PRECIP...WITH ANY PRECIP THAT FALLS BY LATE FRI NIGHT OR
EARLY SAT IN THE SOUTHEAST TRENDING TOWARD SNOW SHOWERS OR
FLURRIES...AS IT WILL BE RATHER COLD ALOFT DESPITE SFC TEMPS NOT
GETTING MUCH BELOW FREEZING IF THAT IN THE LOWER ELEVATIONS. SAT
NIGHT INTO SUN...THERE SHOULD BE AT LEAST A BRIEF RESPITE FROM THE
PRECIP CHANCES...BUT A RATHER PROGRESSIVE PATTERN LEADS TO THE
THREAT OF PRECIP RETURNING BY LATE SUN NIGHT INTO MON AND LINGERING
THROUGH THE END OF THE PERIOD.
TEMPERATURES WILL BEGIN ON THE MILD SIDE...850 MB TEMPS ARE PROGGED
TO BE GENERALLY IN THE 8 TO 10C RANGE OR SO AT THE START OF THE
PERIOD...AND THEN FALL BEHIND THE COLD FRONT TO AROUND -8C OR COLDER
AROUND 12Z ON SAT...BUT THEN MODERATE BY LATE SAT NIGHT AND
SUN...WITH THIS TREND CONTINUING INTO THE START OF THE NEW WEEK. AT
THE SFC THIS SHOULD YIELD RATHER MILD TEMPERATURES AT THE START OF
THE PERIOD...WITH TEMPS FALLING TO NEAR OR SLIGHTLY BELOW NORMAL ON
FRI...WITH THE LARGEST DEPARTURES FROM NORMAL OVER THE WEEKEND.
SATURDAY SHOULD END UP BEING THE COLDEST DAY. TEMPS ARE THEN MORE OR
LESS EXPECTED TO BE NEAR NORMAL AT THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1238 AM EST WED FEB 22 2012
MARGINAL LOW LEVEL WIND SHEAR TONIGHT. REALLY CAN`T JUSTIFY PUTTING IT
IN THE TAFS TONIGHT WITH SUCH MARGINAL CONDITIONS. HOWEVER...IF IT
WARRANTS...IT MAY BE ADDED WITH AN UPDATE A BIT LATER ON.
OTHERWISE...MAIN FORECAST CONCERN WILL BE POTENTIAL FOR CONVECTION
WEDNESDAY AFTERNOON AND EVENING AND SOME GUSTY DAMAGING WINDS WITH
THIS ACTIVITY. RIGHT NOW...TOO MUCH UNCERTAINTY TO PIN DOWN A TIMING
OF THE CONVECTION...BUT SOMETIME BETWEEN 18Z AND 00Z IS A GOOD BET.
MORE SHOWERS DEVELOP ALONG A CONVERGENCE BOUNDARY TOMORROW NIGHT
WHICH WILL GIVE ANOTHER ROUND OF SHOWERS OVERNIGHT. WINDS WILL BE
GUSTY TODAY OUT OF THE SOUTHWEST...BUT NOT QUITE AS STRONG AS
YESTERDAY. WELL THAT IS UNLESS YOU ARE NEAR A THUNDERSTORM WHICH
COULD PRODUCE A STRONG GUST OF WIND.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...HAL
LONG TERM....JP
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
432 AM EST WED FEB 22 2012
.SYNOPSIS...
UNSETTLED WEATHER WITH PERIODS OF RAIN SHOWERS AND ABOVE NORMAL
TEMPERATURES CAN BE EXPECTED TODAY AND THURSDAY AS WEAK DISTURBANCES
MOVE ACROSS THE UPPER OHIO VALLEY. A SURFACE LOW WILL BRING THE BEST
CHANCE OF RAIN ACROSS THE AREA THURSDAY NIGHT INTO FRIDAY WITH A
STRONG COLD FRONT PUSHING ACROSS THE REGION. THIS WILL ALLOW FOR
MORE SEASONABLE WEATHER OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY
IN A SOUTHWESTERLY FLOW WITH VORT ENERGY ALONG A WEAK SHORT WAVE
SHIFTING NORTHEAST OF THE AREA. AT THE SURFACE, A FRONTAL
BOUNDARY HAS SHIFTED EAST OF THE AREA, WITH SOUTHWESTERLY WINDS IN
ITS WAKE.
A FEW LINGERING SHOWERS WILL MOVE ACROSS THE I-80 CORRIDOR,
OTHERWISE A DRY START TO THE DAY CAN BE EXPECTED ACROSS THE AREA.
BY LATE MORNING, CHC POPS RETURN TO THE FORECAST AS THE NEXT AREA
OF WEAK VORT ENERGY MOVES INTO THE AREA AND 1000-300MB COLUMN
SATURATES. THE BEST CHANCE FOR RAIN SHOWERS WILL BE THIS EVENING
FOR AREAS NORTHWEST OF PITTSBURGH. NAM12 INDICATES THE BEST
FORCING WILL SET UP ALONG A CONVERGENCE ZONE THAT WILL DEVELOP
WITH A FRONTAL BOUNDARY.
A WEAK SURFACE LOW PASSING NORTH OF THE AREA WILL PUSH THE
AFOREMENTIONED FRONTAL BOUNDARY WITH LIKELY POPS SOUTHEASTWARD INTO
WESTERN PA AND NORTH-CENTRAL WV TONIGHT.
FOR TEMPS, WARM AIR ADVECTION WILL BE ONGOING THROUGHOUT THE DAY
WITH 850 TEMPS WARMING TO 0-2C ACROSS THE AREA. FORECAST TEMPS
THROUGH THIS PERIOD ARE CLOSE TO A MAV/MET BLEND, AROUND 10 DEGREES
ABOVE NORMAL.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
GFS/NAM SUPPORT THE FRONTAL BOUNDARY STALLING ACROSS THE AREA ON
THURSDAY WITH A FEW RIPPLES IN THE MID-LEVEL FLOW SERVING TO KEEP
CHANCE POPS IN THE FORECAST THROUGH THE DAY. POPS WILL INCREASE LATE
IN THE DAY ON THURSDAY AS A SURFACE LOW DEVELOPS IN THE OHIO VALLEY.
THURSDAY WILL BE THE WARMEST DAY OF THE WEEK, MOST NOTICEABLY FOR
LOCATIONS SOUTH OF THE BOUNDARY. TEMPS WILL WARM TO AROUND 15
DEGREES ABOVE NORMAL WITH IT NOT OUT OF THE QUESTION THAT SOME
LOCATIONS WILL REACH THE 60S.
THE SURFACE LOW WILL CROSS THE AREA THURSDAY NIGHT WITH A MORE
VIGOROUS SHORT WAVE MOVING ACROSS THE EASTERN GREAT LAKES ON FRIDAY.
A STRONG COLD FRONT WILL CROSS EARLY FRIDAY, WITH LIKELY
POPS UNTIL ITS PASSAGE. IN THE WAKE OF THE FRONT, COLD AIR ADVECTION
WILL KICK IN WITH PRECIPITATION BEGINNING TO CHANGE OVER TO SNOW
NORTH OF PITTSBURGH LATE IN THE DAY AS THICKNESSES DECREASE. 850MB
TEMPS WILL ONLY COOL TO AROUND -8C BY FRIDAY EVENING, SO LAKE EFFECT
SHOULD BE LIMITED. HIGHS ON FRIDAY AROUND 5 DEGREES ABOVE NORMAL
WILL LIKELY BE REACHED IN THE MORNING HOURS BEFORE COLDER AND
MORE SEASONABLE AIR IS ADVECTED INTO THE AREA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
PER RECENT HPC-PREFERRED ECMWF MODEL GUIDANCE, EXPECT POST SYSTEM
COOL DOWN TO PROVIDE A MIX WITH SNOW SHOWERS FRIDAY NIGHT AND
SATURDAY. ENSUING HIGH PRESSURE WILL PROVIDE A DRY BREAK SUNDAY INTO
MONDAY.
WITH THE UPPER LEVEL JETSTREAM ORIENTATION BECOMING MORE SOUTHWEST,
A LOW PRESSURE SYSTEM, DEVELOPING ACROSS THE SOUTHERN PLAINS SUNDAY,
WILL MOVE NORTHEAST TO NEW YORK STATE EARLY TUESDAY. HENCE EXPECT A
MIX OF RAIN AND SNOW SHOWERS ACROSS THE UPPER OHIO VALLEY MONDAY
NIGHT AND TUESDAY.
FORECASTED HIGH TEMPERATURES TO BE ABOUT 5 DEGREES COLDER THAN
NORMAL SATURDAY. LOWS SATURDAY NIGHT CAN BE CLOSER TO NORMAL,
DEPENDING ON EXTENT OF LINGERING CLOUDS.
TEMPERATURES SHOULD REBOUND TO NEAR NORMAL LEVEL SUNDAY AND UP TO
ABOUT 5 DEGREES WARMER THAN NORMAL MONDAY INTO TUESDAY.
&&
.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
GENERAL VFR CAN BE EXPECTED THIS MORNING FOR ALL PORTS. A FEW
SCATTERED SHOWERS CAN BE EXPECTED ACROSS THE NORTH THIS MORNING. AS
LOW PRESSURE MOVES INTO THE REGION FROM THE WEST...EXPECT THAT
ANOTHER ROUND OF SHOWERS WILL DEVELOP BY LATE THIS AFTERNOON AND
MAY BRING A CHANCE OF RESTRICTIONS IN SHOWERS.
OUTLOOK...WEDNESDAY NIGHT THROUGH SUNDAY...
RESTRICTIONS POSSIBLE WITH RAIN SHOWERS WEDNESDAY NIGHT AND
THURSDAY. A STRONG COLD FRONTAL PASSAGE DAYTIME FRIDAY...CAN
RESULT IN A MORE PROLONGED PERIOD OF RESTRICTIONS FRIDAY INTO
SATURDAY NIGHT...WITH RAIN SHOWERS DAYTIME FRIDAY FOLLOWED BY COLD
POOL LOW CLOUDS AND SCATTERED SNOW SHOWERS FRIDAY NIGHT INTO
SATURDAY. HIGH PRESSURE SHOULD RESTORE VFR SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
140 AM EST WED FEB 22 2012
.SYNOPSIS...
UNSETTLED WEATHER WITH PERIODS OF RAIN SHOWERS AND ABOVE NORMAL
TEMPERATURES CAN BE EXPECTED TODAY AND THURSDAY AS WEAK DISTURBANCES
MOVE ACROSS THE UPPER OHIO VALLEY. A SURFACE LOW WILL BRING THE BEST
CHANCE OF RAIN ACROSS THE AREA THURSDAY NIGHT INTO FRIDAY WITH A
STRONG COLD FRONT PUSHING ACROSS THE REGION LATE ON FRIDAY. THIS
WILL ALLOW FOR MORE SEASONABLE WEATHER OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
06Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO ACCOUNT
FOR RECENT RADAR TRENDS AND TO WARM TEMPS THROUGH DAWN.
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY
IN A SOUTHWESTERLY FLOW WITH VORT ENERGY ALONG A WEAK SHORT WAVE
CROSSING THE AREA. A BROKEN LINE OF RAIN SHOWERS TRIGGERED BY THE
WAVE ALOFT IS PUSHING ACROSS WESTERN PA. AT THE SURFACE, A
FRONTAL BOUNDARY HAS SHIFTED EAST OF THE AREA, WITH SOUTHWESTERLY
WINDS IN ITS WAKE. THE SW FLOW HAS ALLOWED FOR TEMPERATURES TO
REMAIN FAIRLY STEADY OVERNIGHT.
TODAY...AFTER SHOWERS PUSH EAST THROUGH DAWN, A DRY SWATH OF AIR
ABOVE 600MB WILL SHIFT ACROSS THE AREA AND ALLOW FOR A DRY START
TO THE DAY. AFTER 18Z, CHC POPS RETURN TO THE FORECAST AS THE NEXT
AREA OF WEAK VORT ENERGY MOVES INTO THE AREA AND 1000-300MB COLUMN
SATURATES. THE BEST CHANCE FOR RAIN SHOWERS WILL INTO THIS EVENING
WILL BE NORTHWEST OF PITTSBURGH WITH THE NAM12 INDICATING THE BEST
FORCING SETTING UP ALONG A CONVERGENCE ZONE THAT WILL DEVELOP WITH
A FRONTAL BOUNDARY.
A WEAK SURFACE LOW PASSING NORTH OF THE AREA WILL PUSH THE
AFOREMENTIONED FRONTAL BOUNDARY WITH LIKELY POPS SOUTHEASTWARD INTO
WESTERN PA AND NORTH-CENTRAL WV TONIGHT.
FOR TEMPS, WARM AIR ADVECTION WILL BE ONGOING THROUGHOUT THE DAY
WITH 850 TEMPS WARMING TO 0-2C ACROSS THE AREA. FORECAST TEMPS
THROUGH THIS PERIOD ARE CLOSE TO A MAV/MET BLEND, AROUND 10 DEGREES
ABOVE NORMAL.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
PRECIPITATION PROBABILITIES WILL REMAIN IN THE HIGH CHANCE TO LIKELY
RANGE THROUGH THE SHORT TERM PERIOD. MODELS SHOW A WARM FRONTAL
BOUNDARY SETTING UP ALONG THE OHIO VALLEY WEDNESDAY NIGHT AND
THURSDAY...WHILE A SHORT WAVE MOVES ACROSS THE REGION.
A SURFACE LOW IS EXPECTED TO DEVELOP OVER THE MID MS VALLEY AS THE
MAIN UPPER TROUGH DIGS SOUTHEASTWARD INTO THE UPPER MIDWEST. THE
SURFACE LOW IS PROGGED TO STRENGTHEN AS IT TRACKS NORTHEAST ACROSS
OUR FORECAST AREA THURSDAY NIGHT AND FRIDAY.
TEMPERATURES WILL STAY ABOVE NORMAL WEDNESDAY INTO FRIDAY...WITH
HIGHS REACHING WELL INTO THE 50S AND PUSHING 60 FAR SOUTH THURSDAY
AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
PER RECENT HPC-PREFERRED ECMWF MODEL GUIDANCE, EXPECT POST SYSTEM
COOL DOWN TO PROVIDE A MIX WITH SNOW SHOWERS FRIDAY NIGHT AND
SATURDAY. ENSUING HIGH PRESSURE WILL PROVIDE A DRY BREAK SUNDAY INTO
MONDAY.
WITH THE UPPER LEVEL JETSTREAM ORIENTATION BECOMING MORE SOUTHWEST,
A LOW PRESSURE SYSTEM, DEVELOPING ACROSS THE SOUTHERN PLAINS SUNDAY,
WILL MOVE NORTHEAST TO NEW YORK STATE EARLY TUESDAY. HENCE EXPECT A
MIX OF RAIN AND SNOW SHOWERS ACROSS THE UPPER OHIO VALLEY MONDAY
NIGHT AND TUESDAY.
FORECASTED HIGH TEMPERATURES TO BE ABOUT 5 DEGREES COLDER THAN
NORMAL SATURDAY. LOWS SATURDAY NIGHT CAN BE CLOSER TO NORMAL,
DEPENDING ON EXTENT OF LINGERING CLOUDS.
TEMPERATURES SHOULD REBOUND TO NEAR NORMAL LEVEL SUNDAY AND UP TO
ABOUT 5 DEGREES WARMER THAN NORMAL MONDAY INTO TUESDAY.
&&
.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
CONDITIONS WILL GENERALLY REMAIN VFR OVERNIGHT...EXCEPT FOR POSSIBLE
MVFR RESTRICTIONS IN A BAND OF SHOWERS MOVING THROUGH BY 08Z.
UPSTREAM SITES HAVE OBSERVED UP TO 35KT GUSTS WITH THIS LINE OF
SHOWERS...AND HAVE INCLUDED TEMPO GROUPS FOR WIND GUSTS. REST
OF OVERNIGHT PERIOD SHOULD REMAIN QUIET...THEN SW GUSTS TO 20 KTS
WILL DEVELOP WEDNESDAY MORNING. AS LOW PRESSURE MOVES INTO THE
REGION FROM THE WEST...EXPECT THAT ANOTHER ROUND OF SHOWERS WILL
DEVELOP BY LATE AFTERNOON.
OUTLOOK...WEDNESDAY NIGHT THROUGH SUNDAY...
RESTRICTIONS POSSIBLE WITH RAIN SHOWERS WEDNESDAY NIGHT AND
THURSDAY. A STRONG COLD FRONTAL PASSAGE DAYTIME FRIDAY...CAN
RESULT IN A MORE PROLONGED PERIOD OF RESTRICTIONS FRIDAY INTO
SATURDAY NIGHT...WITH RAIN SHOWERS DAYTIME FRIDAY FOLLOWED BY COLD
POOL LOW CLOUDS AND SCATTERED SNOW SHOWERS FRIDAY NIGHT INTO
SATURDAY. HIGH PRESSURE SHOULD RESTORE VFR SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
108 AM EST WED FEB 22 2012
.SYNOPSIS...
UNSETTLED WEATHER WITH PERIODS OF RAIN SHOWERS AND ABOVE NORMAL
TEMPERATURES CAN BE EXPECTED TODAY AND THURSDAY AS WEAK DISTURBANCES
MOVE ACROSS THE UPPER OHIO VALLEY. A SURFACE LOW WILL BRING THE BEST
CHANCE OF RAIN ACROSS THE AREA THURSDAY NIGHT INTO FRIDAY WITH A
STRONG COLD FRONT PUSHING ACROSS THE REGION LATE ON FRIDAY. THIS
WILL ALLOW FOR MORE SEASONABLE WEATHER OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
06Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO ACCOUNT
FOR RECENT RADAR TRENDS AND TO WARM TEMPS THROUGH DAWN.
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY
IN A SOUTHWESTERLY FLOW WITH VORT ENERGY ALONG A WEAK SHORT WAVE
CROSSING THE AREA. A BROKEN LINE OF RAIN SHOWERS TRIGGERED BY THE
WAVE ALOFT IS PUSHING ACROSS WESTERN PA. AT THE SURFACE, A
FRONTAL BOUNDARY HAS SHIFTED EAST OF THE AREA, WITH SOUTHWESTERLY
WINDS IN ITS WAKE. THE SW FLOW HAS ALLOWED FOR TEMPERATURES TO
REMAIN FAIRLY STEADY OVERNIGHT.
TODAY...AFTER SHOWERS PUSH EAST THROUGH DAWN, A DRY SWATH OF AIR
ABOVE 600MB WILL SHIFT ACROSS THE AREA AND ALLOW FOR A DRY START
TO THE DAY. AFTER 18Z, CHC POPS RETURN TO THE FORECAST AS THE NEXT
AREA OF WEAK VORT ENERGY MOVES INTO THE AREA AND 1000-300MB COLUMN
SATURATES. THE BEST CHANCE FOR RAIN SHOWERS WILL INTO THIS EVENING
WILL BE NORTHWEST OF PITTSBURGH WITH THE NAM12 INDICATING THE BEST
FORCING SETTING UP ALONG A CONVERGENCE ZONE THAT WILL DEVELOP WITH
A FRONTAL BOUNDARY.
A WEAK SURFACE LOW PASSING NORTH OF THE AREA WILL PUSH THE
AFOREMENTIONED FRONTAL BOUNDARY WITH LIKELY POPS SOUTHEASTWARD TO
ACROSS INTO WESTERN PA AND NORTH-CENTRAL WV TONIGHT.
FOR TEMPS, WARM AIR ADVECTION WILL BE ONGOING THROUGHOUT THE DAY
WITH 850 TEMPS WARMING TO 0-2C ACROSS THE AREA. FORECAST TEMPS
THROUGH THIS PERIOD ARE CLOSE TO A MAV/MET BLEND, AROUND 10 DEGREES
ABOVE NORMAL.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
PRECIPITATION PROBABILITIES WILL REMAIN IN THE HIGH CHANCE TO LIKELY
RANGE THROUGH THE SHORT TERM PERIOD. MODELS SHOW A WARM FRONTAL
BOUNDARY SETTING UP ALONG THE OHIO VALLEY WEDNESDAY NIGHT AND
THURSDAY...WHILE A SHORT WAVE MOVES ACROSS THE REGION.
A SURFACE LOW IS EXPECTED TO DEVELOP OVER THE MID MS VALLEY AS THE
MAIN UPPER TROUGH DIGS SOUTHEASTWARD INTO THE UPPER MIDWEST. THE
SURFACE LOW IS PROGGED TO STRENGTHEN AS IT TRACKS NORTHEAST ACROSS
OUR FORECAST AREA THURSDAY NIGHT AND FRIDAY.
TEMPERATURES WILL STAY ABOVE NORMAL WEDNESDAY INTO FRIDAY...WITH
HIGHS REACHING WELL INTO THE 50S AND PUSHING 60 FAR SOUTH THURSDAY
AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
PER RECENT HPC-PREFERRED ECMWF MODEL GUIDANCE, EXPECT POST SYSTEM
COOL DOWN TO PROVIDE A MIX WITH SNOW SHOWERS FRIDAY NIGHT AND
SATURDAY. ENSUING HIGH PRESSURE WILL PROVIDE A DRY BREAK SUNDAY INTO
MONDAY.
WITH THE UPPER LEVEL JETSTREAM ORIENTATION BECOMING MORE SOUTHWEST,
A LOW PRESSURE SYSTEM, DEVELOPING ACROSS THE SOUTHERN PLAINS SUNDAY,
WILL MOVE NORTHEAST TO NEW YORK STATE EARLY TUESDAY. HENCE EXPECT A
MIX OF RAIN AND SNOW SHOWERS ACROSS THE UPPER OHIO VALLEY MONDAY
NIGHT AND TUESDAY.
FORECASTED HIGH TEMPERATURES TO BE ABOUT 5 DEGREES COLDER THAN
NORMAL SATURDAY. LOWS SATURDAY NIGHT CAN BE CLOSER TO NORMAL,
DEPENDING ON EXTENT OF LINGERING CLOUDS.
TEMPERATURES SHOULD REBOUND TO NEAR NORMAL LEVEL SUNDAY AND UP TO
ABOUT 5 DEGREES WARMER THAN NORMAL MONDAY INTO TUESDAY.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
CONDITIONS WILL GENERALLY REMAIN VFR OVERNIGHT...EXCEPT FOR POSSIBLE
MVFR RESTRICTIONS IN A BAND OF SHOWERS MOVING THROUGH BY 08Z.
UPSTREAM SITES HAVE OBSERVED UP TO 30 KT GUSTS WITH THIS LINE OF
SHOWERS...AND HAVE INCLUDED TEMPO GROUPS FOR THESE CONDITIONS. REST
OF OVERNIGHT PERIOD SHOULD REMAIN QUIET...THEN SW GUSTS TO 20 KTS
WILL DEVELOP WEDNESDAY MORNING. AS LOW PRESSURE MOVES INTO THE
REGION FROM THE WEST...EXPECT THAT ANOTHER ROUND OF SHOWERS WILL
DEVELOP BY LATE AFTERNOON.
OUTLOOK...WEDNESDAY NIGHT THROUGH SUNDAY...
RESTRICTIONS POSSIBLE WITH RAIN SHOWERS WEDNESDAY NIGHT AND
THURSDAY. A STRONG COLD FRONTAL PASSAGE DAYTIME FRIDAY...CAN
RESULT IN A MORE PROLONGED PERIOD OF RESTRICTIONS FRIDAY INTO
SATURDAY NIGHT...WITH RAIN SHOWERS DAYTIME FRIDAY FOLLOWED BY COLD
POOL LOW CLOUDS AND SCATTERED SNOW SHOWERS FRIDAY NIGHT INTO
SATURDAY. HIGH PRESSURE SHOULD RESTORE VFR SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1209 AM EST WED FEB 22 2012
.UPDATE...
ISSUED AT 1011 PM EST TUE FEB 21 2012
MAIN FCST CONCERN OVERNIGHT IS SNOW ACCUMULATIONS OVER THE W.
WATER VAPOR IMAGERY SHOWS MID LEVEL LOW MOVING OVER WRN LAKE
SUPERIOR ATTM WITH ASSOCIATED MOIST...CYCLONIC FLOW SUPPORTING
-SN/-SHSN ACROSS NE MN INTO FAR NW WI AND W/NCNTRL UPPER MI. MORE
CONVECTIVE LOOKING -SHSN SPREADING ACROSS WRN UPPER MI PER KMQT
RADAR IMAGERY ARE JUST AHEAD OF RUC ANALYZED VORT MAX. PROBABLY SOME
DECENT SNOW RATES OCCURRING WITH THE 28+DBZ ECHOES...THOUGH SHORT
LIVED. FARTHER W...SNOW LOOKS LESS CONVECTIVE ON KDLH RADAR.
UPSTREAM...00Z KINL SOUNDING SHOWED DEEP MOISTURE TO 500MB.
HOWEVER...CAA AT THE LOWER LEVELS HAS BEEN MINIMAL TODAY AS 12Z AND
00Z 850MB TEMPS WERE -7C. THIS WILL PUT AIR MASS FLOWING OVER WRN
LAKE SUPERIOR AT THE MARGINAL THRESHOLD FOR LAKE ENHANCEMENT
OVERNIGHT. CONSIDERED POSSIBLE ADVY FOR ONTONAGON THRU KEWEENAW
OVERNIGHT INTO WED MORNING AS THIS WETTER SNOW (RATIO UNDER 20 TO 1)
FALLS UNDER LOWER ADVY CRITERIA (MAJORITY OF AREA AT LEAST 3 INCHES
IN 12HRS). GIVEN MARGINAL LAKE ENHANCEMENT CONDITIONS...OPTED TO
HOLD OFF ON ADVY ATTM. WOULD NOT BE SURPRISED TO SEE SOME OF THE
HIGHER TERRAIN AREAS AROUND THE PORCUPINE MTNS...BERGLAND...
ROCKLAND...TWIN LAKES AND PAINESDALE END UP AROUND 4 INCHES BY LATE
WED MORNING. HOWEVER...MAJORITY OF AREA SHOULD END UP IN THE 1-3 INCH
RANGE.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 400 PM EST TUE FEB 21 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER NRN
MN WITH A SHORTWAVE TROUGH EXTENDING INTO NW WI. 850-500 MB QVECTOR
CONV AND MID LEVEL FGEN ASSOCIATED WITH THE SHRTWV SUPPORTED A BAND
OF SNOW ACROSS CNTRL UPPER MI. SO...FAR ACCUMULATIONS HAVE BEEN
LIGHT...GENERALLY LESS THAN AN INCH. AT THE SFC...A 992 MB LOW WAS
LOCATED NEAR KINL WITH MOST OF THE SNOW AHEAD OF A TROUGH EXTENDING
TO THE SE THROUGH WRN UPPER MI INTO NE WI. ADDITIONAL SNOW OVER NE
MN WITH WRAP-AROUND MOISTURE NEAR THE MID LEVEL LOW WAS MOVING BACK
INTO NW WI.
RADAR TRENDS AND NAM/RUC FCST SUGGEST THAT THE INITIAL SNOWBAND WILL
MOVE OUT OF CNTRL UPPER MI INTO THE ERN CWA LATE THIS AFTERNOON AND
EVENING. THE SNOW AREA OVER MN IS ALSO EXPECTED TO SHIFT INTO WRN
UPPER MI THIS EVENING BRINGING POTENTIAL FOR ADDITIONAL LIGHT
ACCUMULATIONS OF AN INCH OR TWO. EVEN THOUGH THE STRONGER SYNOPTIC
FORCING IS FCST NEAR KIWD... THE COMBINATION OF CONVERGENT WRLY FLOW
AND 850 MB TEMPS DROPPING TO AROUND -8C WILL ALSO RESULT IN SOME
LAKE ENHANCED SNOW OVER NW UPPER MI WITH SNOWFALL AMOUNTS INTO THE 1
TO 3 INCH RANGE. AS THE WINDS VEER SLIGHTLY WED...THE LAKE ENHANCED
SNOW SHOULD ALSO MOVE INTO LOCATIONS NEAR LAKE SUPERIOR EAST OF
MUNISING. THE REMAINING SNOW OVER THE WEST WILL DIMINISH WED AS
HIGH PRESSURE AND DRIER AIR MOVE INTO THE AREA BEHIND THE DEPARTING
MID LEVEL LOW.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 400 PM EST TUE FEB 21 2012
THE 500MB LOW CURRENTLY OVER N MN THIS AFTERNOON WILL BE ALONG THE
ONTARIO/QUEBEC BORDER TO BEGIN THIS PERIOD. THE NEXT TROUGH SLIDING
IN FROM THE NW WILL BE BROAD...STRETCHING FROM W MANITOBA TO E LAKE
SUPERIOR/CENTRAL LAKE MI THURSDAY AFTERNOON. FCST MODELS BEGIN TO
DIVERGE EARLIER THAN NORMAL...THURSDAY AFTERNOON /DAY 2/.
THE 21/06Z NAM IS A QUICK OUTLIER...WITH A CLOSED LOW DEVELOPING
NEAR THE MACKINAC BRIDGE...BEFORE SHIFTING TO S QUEBEC FRIDAY
AFTERNOON. WHILE THE 21/06Z GFS HAS A SIMILAR TREND...IT IS APPROX 6
HOURS SLOWER. THE 21/09Z SREF TENDS TO FOLLOW A SOLUTION SIMILAR TO
THE GFS...WHILE THE 21/00Z CANADIAN IS AN AVERAGE BETWEEN THE
GFS/SREF AND THE MUCH SLOWER 21/00Z ECMWF /LOW OVER W ONTARIO WHILE
THE GFS HAS IT OVER THE S ONTARIO/QUEBEC BORDER/. THE ECMWF DOES NOT
PLACE THE LOW OVER THE S ONTARIO/QUEBEC BORDER UNTIL 12Z
SATURDAY...OR 18HRS BEHIND THE GFS. WILL PUSH THIS FORECAST CLOSER
TO A GFS SOLUTION THROUGH THE END OF THE WORK WEEK. THIS WILL RESULT
IN UPPER MI AND LAKE SUPERIOR STUCK BETWEEN THE FIRST SFC LOW
EXITING INTO QUEBEC AT 00Z THURSDAY...WITH THE STRONGER LOW
DEVELOPING OVER THE N PLAINS AND CENTRAL CANADA. A WEAK SFC TROUGH
WILL CONNECT THE TWO. THE MOST SIGNIFICANT CONTRAST THE MODELS CAN
BE SEEN OFF THE 00Z FRIDAY SFC MAP. THERE IS A CLUSTER OF MODELS
/GFS/NAM/SREF/ WITH THE LOW OVER CENTRAL TO N LOWER MI. BY CONTRAST
THE CANADIAN HAS IT ALONG THE LOWER MI/IA/OH BORDER...WITH THE ECMWF
ALONG THE CONFLUENCE OF THE OHIO AND MISSISSIPPI RIVERS. AS STATED
ABOVE...WILL PUSH THE FCST TO A MORE CENTRAL LOWER MI SOLUTION AT
00Z FRIDAY. THIS WILL KEEP THE BULK OF THE SYNOPTIC MOISTURE FALLING
JUST SOUTH OF THE CWA.
AFTER 18Z FRIDAY ALL OF THE SOLUTIONS COME INTO SOME BASIC AGREEMENT
OVER OUR CWA...WITH N TO NW WINDS AND 850MB TEMPS IN THE -8 TO -12C
RANGE. 850MB TEMPS OF -14 TO -16C SHOULD BE COMMON BY SUNDAY
AFTERNOON...BEFORE WAA ON MORE SW WINDS TAKE HOLD SATURDAY NIGHT.
STRONG SSW WINDS WILL LIKELY TAKE HOLD SUNDAY AFTERNOON INTO SUNDAY
NIGHT /DEPENDING ON THE TIMING OF THE NEXT LOW. THE ECMWF ENDS UP
BEING ROUGHLY 12 HOURS SLOWER THAN THE GFS WITH THIS NEXT SYSTEM
COMING OUT OF THE PLAINS. A STRONGER MORE NORTHERLY LOW OFF THE
ECMWF WOULD BRING 850MB TEMPS OF 2C...COMPARED TO THE WARMEST
READINGS OFF THE GFS OF -6C. AT 00Z TUESDAY THE SFC 983MB SFC LOW
OFF THE ECMWF IS OVER NE MN...WHILE AT THE SAME TIME THE
WEAKER/QUICKER GFS HAS A 1003MB LOW OVER FAR S QUEBEC. GIVEN THE
LOWER CONFIDENCE WITH THE FORECAST WILL NOT DIVE TO MUCH INTO THE
SPECIFICS...AND KEEP A CONSENSUS GOING FROM SATURDAY NIGHT ON. EVEN
WITH ALL THE DIFFERENCES...SUNDAY NIGHT LOOKED TO BE A GOOD
OPPORTUNITY TO INCLUDE LIKELY POPS OVER S CENTRAL UPPER MI.
OTHERWISE...WILL KEEP CHANCE OF LESS POPS GOING THROUGH MUCH OF THE
PERIOD WITH LOWER THAN NORMAL CONFIDENCE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1208 AM EST WED FEB 22 2012
MOISTURE/-SN/-SHSN WRAPPING AROUND MIDLEVEL LOW MOVING ACROSS WRN
LAKE SUPERIOR WILL AFFECT KIWD/KCMX/KSAW OVERNIGHT INTO THE MORNING
HRS. KCMX WILL BE IMPACTED MOST AS FAVORABLE UPSLOPE WESTERLY WIND
WILL LIKELY HOLD CONDITIONS TO IFR FOR MUCH OF THE OVERNIGHT. SOME
BRIEF PERIODS OF LIFR AND MVFR WILL ALSO OCCUR. AT KIWD...MVFR
CONDITIONS SHOULD PREVAIL WITH LESS LAKE INFLUENCE. AT KSAW...
DOWNSLOPING WIND COMPONENT SHOULD RESULT IN HIGHER MVFR CIGS...AND
-SN PROBABLY WON`T CAUSE MUCH VIS RESTRICTION. IMPROVEMENT WILL
OCCUR DURING THE DAY TODAY AS MIDLEVEL LOW DEPARTS...THOUGH MVFR
CONDITIONS WILL LIKELY LINGER AT KIWD/KCMX.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 400 PM EST TUE FEB 21 2012
AS LOW PRESSURE SLIDES EASTWARD THROUGH NRN LAKE SUPERIOR AND
INTO QUEBEC BY WED AFTERNOON...WRLY WINDS WILL INCREASE TO 20 TO 30
KT TONIGHT INTO WED. WINDS WILL DIMINISH LATE WED INTO WED NIGHT AS
HIGH PRES BUILDS INTO THE UPPER GREAT LAKES. WINDS WILL THEN REMAIN
RELATIVELY LIGHT INTO UNTIL FRI WHEN NRLY WINDS OF 15 TO 25 KT ARE
POSSIBLE AS LOW PRESSURE MOVES TO THE SOUTH OF THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...ROLFSON
SHORT TERM...JLB
LONG TERM...KF
AVIATION...ROLFSON
MARINE...JLB
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1255 AM EST WED FEB 22 2012
.SYNOPSIS...
HIGH PRESSURE WILL MOVE INTO THE AREA BEHIND A DEPARTING COLD FRONT.
A STRONGER FRONT IS EXPECTED TO MOVE INTO THE CAROLINAS EARLY ON
FRIDAY. HIGH PRESSURE WILL THEN RETURN OVER THE WEEKEND AND LINGER
INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
RELATIVELY QUIET AT MIDNIGHT ACROSS THE REGION. MAIN CONCERN IS THE
DEVELOPMENT OF LOW STRATUS FROM THE SW DURING THE PRE-DAWN
HOURS...AS CONSIDERABLY HIGHER DEWPT AIR IS SLOWLY CREEPING NWD FROM
THE GULFMEX. NOTHING SIGNIFICANT SHOWED UP ON SATELLITE IMAGERY
YET...SO THE SKY COVER WAS KEPT MOSTLY CLEAR THROUGH SUNRISE. TEMPS
WILL BE TWEAKED FOR THE RECENT OBS TREND AS WELL.
REMAINDER OF PREVIOUS DISCUSSION...
AS OF 950 PM TUE...THE HRRR AND WORKSTATION WRF...ALONG WITH THE 18
UTC NAM BUFKIT...CONTINUE TO SHOW STRATUS DEVELOPING OVER NE
GA...THE UPSTATE AND THE SRN NC PIEDMONT LATE TONIGHT. THIS WILL BE
MORE IMPORTANT FOR TAF GENERATION PURPOSES LATER TONIGHT.
OTHERWISE...I/VE RAISED DEWPOINTS ACROSS THE SOUTH ONCE AGAIN. THE
WINDS HAVE DECOUPLED QUICKLY THIS EVENING...BUT SHOULD INCREASE INTO
THE 4 TO 6 KT RANGE LATER TONIGHT AND THE LLVL JET STRENGTHENS TO
AROUND 30 KTS OVER THE FA.
A SHORT WAVE ENTERS THE AREA WED AFTERNOON AS MID LEVEL FLOW BECOMES
A LITTLE MORE AMPLIFIED. ANOTHER SLIGHTLY STRONGER FRONT WILL MOVE
INTO THE AREA AS WELL. FORCING AND MOISTURE IS BETTER WITH THIS
SYSTEM. THAT SAID...THE FORCING IS NOT VERY STRONG WITH ONLY WEAK
UPPER DIVERGENCE. THE MOISTURE IS NOT VERY COPIOUS EITHER. STILL...
IT APPEARS THAT THEY WILL BE ENUF FOR GOOD CHC POP TO DEVELOP OVER
THE MTNS. POP DROPS OFF TO SLIGHT CHC SOUTH OF I-85 AWAY FROM THE
BEST MOISTURE AND FORCING. INSTABILITY IS ON THE UPSWING DURING THE
AFTERNOON...BUT IT REMAINS QUESTIONABLE WHETHER IT BECOMES STRONG
ENUF FOR ANY TSRA TO DEVELOP. THEREFORE...HAVE CONTINUED THE PREV
TREND OF NO TS MENTION FOR NOW. SHOULD BE ANOTHER GUSTY AFTERNOON AS
DEEP MIXING TAPS RELATIVELY STRONG LOW LEVEL FLOW. IN FACT...IT
COULD BE STRONG ENUF FOR A LAKE WIND ADV. WILL LET NEXT SHIFT MAKE
THAT DECISION AS THE MAGNITUDE IS STILL IN QUESTION. HIGHS WILL BE 5
TO 10 DEGREES ABOVE NORMAL.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY/...
AS OF 230 PM TUESDAY...A WARM AND MOIST AIR MASS WILL DEVELOP OVER
THE REGION DURING THE MID WEEK. WEDNESDAY EVENING...A SHORT WAVE IS
EXPECTED TO RIPPLE WITHIN A LONGWAVE TROF AXIS ACROSS THE SOUTHERN
APPALACHIAN REGION DURING THE EARLY EVENING HOURS. GUSTY SOUTHWEST
WINDS ARE FORECAST TO BRING RISING DEWPOINTS ACROSS THE FORECAST
AREA...GENERALLY RANGING IN THE MID TO UPPER 40S. AN AREA OF
TSRA/SHRA IS EXPECTED TO DEVELOP DURING THE AFTERNOON UPSTREAM OF
THE REGION...STEERING FLOW WILL TRANSPORT THE CONVECTION NORTHEAST
ACROSS GEORGIA AND THE WESTERN CAROLINAS. DURING THE EVENING
HOURS...FORECAST SOUNDINGS INDICATE THAT CAPE VALUES WILL RANGE FROM
100 TO 400 J/KG ACROSS THE CWA. IN ADDITION...SWEAT VALUES WILL PEAK
BETWEEN 300-400 WITH EHI VALUES AROUND 1...THE CORE OF A H3 140 KT
JET WILL REMAIN ACROSS THE MIDLANDS AND COASTAL AREAS. GIVEN THE
BROAD FIELD OF WEAK INSTABILITY AND STRONG WIND FIELDS...IT IS
REASONABLE TO EXPECT ORGANIZED MCS TO SURVIVE INTO THE EVENING HOURS
ACROSS THE CWA. I WILL MAINTAIN CHC POPS ACROSS THE MTNS AND
FOOTHILLS...SCHC EAST OF I-85. THE POTENTIAL EXIST THAT ANY
ORGANIZED CONVECTION COULD PRODUCE DAMAGING WINDS DURING THE
EVENING...SUPPORTED BY SPC DY2 SLIGHT RISK AREA. I WILL HIGHLIGHT
THE RISK FOR DAMAGING TSRA WINDS IN THE HWO.
THROUGH THE REST OF WEDNESDAY NIGHT...ONGOING SOUTHWEST WINDS AND
THICK SKY COVER WILL KEEP TEMPERATURES MILD OVERNIGHT. USING A BLEND
OF GUIDANCE...I WILL FORECAST LOWS FROM THE L40S ACROSS THE MTNS TO
L50S EAST.
THURSDAY...PRESSURE GRADIENT ACROSS THE FORECAST AREA WILL REMAIN
BETWEEN 3 TO 4 MBS. FORECAST SOUNDINGS INDICATE THE MIXING MAY
REACH UP TO H85 DURING THE AFTERNOON. SOUTHWEST WINDS WILL LIKELY
INCREASE THROUGH THE DAY...PEAKING BETWEEN 15 TO 20 KTS WITH GUSTS
TO 25 TO 30 KTS. THESE WINDS WILL REINFORCE THE WARM AND MOIST AIR
MASS ACROSS THE REGION...WITH DEWPOINTS REMAINING WELL INTO THE 40S.
H85 TEMPS MAY REACH ABOVE 10C DURING THE AFTERNOON AS A COLD FRONT
PUSHES INTO MIDDLE TN. MOS CONSENSUS SUPPORTS HIGH TEMPERATURES IN
THE U60S ACROSS THE MTNS VALLEYS TO LOW TO MID 70S EAST...OR WITHIN
A COUPLE OF DEGREES OF RECORD HIGHS.
THURSDAY NIGHT...NAM AND GFS INDICATE THAT COLD FRONT WILL SWEEP
ACROSS THE SOUTHERN APPALACHIAN REGION DURING THE LATE NIGHT HOURS.
WIND FIELDS ALONG AND AHEAD OF THE FRONT BECOME STRONG WITH 0 TO 1
KM HELICITY EXCEEDING 300 M2/S2. NAM CAPE SHOWS THAT A BAND OF WEAK
CAPE WILL REMAIN ALONG AND AHEAD OF THE FRONT. THIS ENVIRONMENT MAY
SUPPORT ONGOING GA/TN MCS TO TRACK ACROSS THE REGION DURING THE
NIGHT. THESE SITUATIONS TYPICALLY BRING TSRA EAST QUICKER THAN
MODEL RATES...BUT EVEN USING THE MORE STABLE GUIDANCE IT APPEARS
THAT SVR WINDS ARE POSSIBLE. WE WILL ALSO HIGHLIGHT THIS EVENT IN
THE HWO. MIN TEMPERATURES ARE FORECAST TO RANGE FROM U40S ACROSS THE
MTN VALLEYS TO LOW TO MID 50S EAST.
FRIDAY...WINDS WILL VEER WEST TO EVENTUALLY NORTHWEST IN THE WAKE OF
THE COLD FRONT. I WILL INDICATE DECREASING POPS AND SKY WITH THE
PASSAGE OF THE FRONT. MODELS INDICATE THAT H85 TEMPS WILL FALL
THROUGH THE DAY...WITH TEMPS COOLING BETWEEN 8 TO 10 C DURING THE
DAYLIGHT HOURS. I WILL WILL INDICATE A MID DAY HIGH IN THE U50S
ACROSS THE MTNS TO U60S EAST...THEN GRADUAL COOLING THROUGH THE
AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 2 PM TUESDAY...THE GLOBAL MODELS ARE HAVING TYPICAL ISSUES
WITH THE SPLIT FLOW REGIME IN PLACE AT THE BEGINNING OF THE PERIOD.
THEREFORE...CONFIDENCE IN THE MEDIUM RANGE FORECAST IS MUCH LOWER
THAN USUAL. THE MAIN PROBLEMS ARE IN THE SOUTHERN STREAM...
SPECIFICALLY IN TIMING THE KICKING OUT OF THE UPPER LOW THAT IS
CURRENTLY OVER THE BAJA AREA. THE 00Z ECMWF KICKS THIS ENERGY OUT
OVER THE SOUTHEAST FRIDAY (ABOUT 24 HOURS LATER THAN YESTERDAYS
RUNS). MEANWHILE...THE GFS DOESNT DO THIS UNTIL SUNDAY NIGHT. THE
MODELS HAVE BEEN UP TO THESE TYPES OF SHENANIGANS FOR SEVERAL DAYS
NOW WITH REGARD TO THIS SOUTHERN STREAM ENERGY AND WHETHER/WHEN TO
TRANSITION TO A PHASED FLOW REGIME. WE/VE OPTED TO STOP PRETENDING
THAT WE OR THE MODELS HAVE ANY CLUE WHAT/S GOING TO HAPPEN PAST THE
SHORT TERM PERIOD. POPS WILL THEREFORE BE HELD BELOW CHANCE THROUGH
THE MEDIUM RANGE...WHILE NEAR-NORMAL TEMPS WILL BE FORECAST IN THE
WAKE OF FRIDAYS FROPA.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE...THE MAIN ISSUE IS THE POSSIBILITY OF LOW
STRATUS DEVELOPING IN A LIGHT RETURN FLOW FROM THE SW. A PLUME OF
HIGHER DEWPT AIR WAS MOVING NWD FROM THE GULFMEX AS OF 05Z. PREVIOUS
GUIDANCE SHOWED THE POSSIBILITY OF SOME LOW STRATUS DEVELOPING
DURING THE EARLY MORNING HOURS. IT HAS NOT DEVELOPED YET. THE 00Z
RUN OF THE NAM HAS BACKED OFF A BIT...SO THE TAFS WILL AS WELL...
UNTIL SOME SIGN OF DEVELOPMENT IS SEEN. CONFIDENCE ONLY ABOUT 40 PCT
THAT STRATUS WILL DEVELOP...SO IT WAS LEFT OUT. OTHERWISE...LOW
LEVEL MOISTURE WILL INCREASE TODAY AS WILL SW FLOW AHEAD OF A
SURFACE BOUNDARY APPROACHING FROM THE WEST. THIS RESULTS IN A PERIOD
OF GUSTY WINDS AT MOST TAF SITES AND AN UNCOMMON CROSS VALLEY WIND
AT KAVL FOR THE AFTERNOON. THE MODELS SUGGEST CONVECTIVE DEVELOPMENT
IN THE GREAT VALLEY OF TN THIS AFTERNOON...WITH THE CONVECTION
DEVELOPING ACROSS THE MTNS IN THE AFTERNOON AND INTO THE PIEDMONT IN
THE EVENING. CONFIDENCE TOO LOW TO INCLUDE THIS IN THE TAFS WITH
THIS ISSUANCE BUT IT WILL BE REVISITED WITH THE NEXT ONE. THE
MOISTENING BOUNDARY LAYER MAY VERY WELL RESULT IN AN MVFR CLOUD DECK
BY LATE EVENING.
OUTLOOK...PCPN CHANCES WILL CONTINUE THRU THURSDAY. CEILING AND VIS
RESTRICTIONS ARE POSSIBLE AROUND CONVECTION DURING THIS TIME. GUSTY
SW WINDS WILL DEVELOP AGAIN ON THU. LOW PRESSURE WILL DEVELOP OVER
THE DEEP SOUTH THU NIGHT AND FRI. WIDESPREAD LOW CIGS AND PCPN ARE
EXPECTED AS THE LOW DEVELOPS. DRIER AND COLDER WEATHER WILL FOLLOW
FOR THE WEEKEND.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...MCAVOY/PM
SHORT TERM...NED
LONG TERM...JDL
AVIATION...PM
AREA FORECAST DISCUSSION...UPDATED
NWS TALLAHASSEE FL
515 AM EST Wed Feb 22 2012
...Updated for issuance of Dense Fog Advisory and for 12Z aviation
package...
.Update...
A dense fog advisory has been issued until 9AM EST/8AM CST for
portions of the FL Panhandle, southeast Alabama, southwest Georgia,
and the western Big Bend. Numerous locations within the advisory
area have seen visibilities drop to one quarter mile or less early
this morning. These low visibilities will make travel difficult in
spots until mid-morning when conditions will begin to improve.
.SYNOPSIS...
08Z water vapor and H4 RUC analysis shows northern stream flow
arriving over the Pacific Northwest/British Columbia coast before
carving out a broad longwave trough over much of the CONUS to the
east of the continental divide. A weak impulse embedded within this
flow over the southern Plains will quickly slide eastward toward the
forecast area by this evening. Southern stream flow extends from the
west coast of Mexico eastward over the northern Gulf/Gulf coastal
region, and continues to pump abundant mid/upper level moisture
overhead. One other feature of note, is a cutoff upper low spinning
over the Baja region of Mexico. This energy has been a real "thorn
in our side" the past couple of days as global models have had
significant difficulty with its evolution. Will discuss this further
below.
At the surface, ridge axis runs from the central FL peninsula
northward to our forecast area. Light winds and a slow low level
moisture return on the western periphery of the ridge is resulting
in area of fog this morning. Temperatures are generally in the upper
40s to middle 50s, and with expanding areas of fog/lower clouds,
don`t anticipate much further of a temperature drop.
&&
.SHORT TERM (Today through Friday)...
Today, Weather will start out quiet, however changes will take place
by the end of the day. Surface high pressure currently in place will
shift south and east with time in response to adjusting mass fields
ahead of the weak approaching northern stream impulse. Ahead of this
impulse, low/mid level SW flow will increase allowing a broad WAA
regime to expand across the area. GFS/ECMWF show increasing low
level ascent/upglide along the 295-310K surfaces overtaking the
area, with the deepest ascent/moisture fields over the southern/SE
zones. Always a tough call in these scenarios as to just where the
most numerous showers will end up. Generally speaking, NWP guidance
is often too slow in the development of upglide/WAA precipitation.
Took this into account and allowed showers to develop into the
coastal areas of the FL panhandle around noon, and then quickly
expand north and east through the afternoon. Based on general NWP
agreement in where the deeper lift will occur, have highest rain
chances 60-80% south of a line from Dothan to Moultrie to Valdosta.
Still expect at least some shower activity north of this line based
on latest hi-res ensemble CAM guidance, however confidence in the
overall coverage is lower, and will take PoPs down to 40-50%. In
addition, will add isolated thunderstorms to the grids due to
showalter indices between -2 to 0. Not out of the question that a
few of these storms may be on the strong side (wind gust the main
threat) as strengthening flow will result in deep layer shear
profiles supportive of organized convection.
Tonight, Weak synoptic forcing and best upglide will shift into the
eastern Big Bend/Suwannee River Valley by later this evening, and
then exit our region around midnight. Looks like there may be just
enough forcing left behind to support isolated showers into the
early morning hours, however doesn`t look too impressive and will
allow Pops to drop below 20% for all zones. SW low level flow off
the Gulf will keep our temps warm with lows in the mid/upper
50s inland and lower 60s at the coast.
Thursday, Upper level pattern will begin to amplify as shortwave
energy drops down the backside of the main northern stream trough.
Associated surface low pressure will push east from the Central
Plains toward the Ohio Valley, with a trailing cold front down along
the MS valley. Deep southerly low level flow will give us a rather
warm and humid day for the end of February. Good diurnal mixing and
850mb temps around 14-15C will allow many inland locations to reach
the mid/upper 70s (perhaps a few spots touching 80). Along the
immediate coast temps will be a bit cooler with the flow off the
shelf waters. Model agreement in several hundred J/KG of mixed layer
CAPE during the afternoon argued for a slight rain chances (a
few isolated "pop-up" showers/storms away from the coast).
Friday,
Threat for severe storms is not gone, however the overall threat
has lowered from 24 hours ago. Global guidance members now all agree
that the northern stream trough will not dig enough to grab the
cutoff energy over the Mexican Baja and eject it eastward fast
enough for phasing. This is good news in general as resulting
synoptic lift and kinematic fields appear not as impressive. As the
upper trough moves toward the eastern CONUS, the associated surface
cold front will still approach and cross our region, with a good
chance for a round of showers and storms. GFS has a faster frontal
passage and argues for the best rain chances late Thursday night
into Friday, while the ECMWF suggest during the day Friday/Friday
night. As mentioned above, although the threat has lowered, can`t
let our guard down in term of severe potential, as sufficient shear
for organized convection is still progged by the global guidance.
Will continue to monitor.
&&
.LONG TERM (Friday Night through next Wednesday)...
Guidance is not in good agreement for much of the extended period.
Much of the discrepancy through the weekend is tied to the evolution
of the cut-off low currently dropping into the Baja region of
Mexico. Guidance has all trended towards a much slower solution as
this feature treks east towards the Gulf of Mexico. However, the 00Z
ECMWF/Canadian have the feature picked up by the northern stream
flow Friday night, while the GFS is 12+ hours slower. The main
impact of this slower motion is to develop a more substantial sfc
reflection over the SW Gulf late Saturday which helps push an large
area of overrunning precip into the forecast are on Sunday. The
ECMWF/Canadian solution keeps the area dry for this period. HPC
prefers to quicker solution, and will follow suit with a dry
forecast for Sunday.
Guidance is in somewhat better agreement for Monday into Tuesday as
return flow increases ahead of a deepening trough over the central
states. This should allow for at least scattered PoPs for the region
as a front moves into the southeastern states. Guidance then
diverges substantially with the evolution of the large scale flow
with a multitude of solutions. Guidance seems to generally indicate
some chance for precip Tuesday into Wednesday, so have broadbrushed
slight chance PoPs through the end of the period.
&&
.MARINE...
Surface high pressure will settle south of the forecast waters
through the day allowing a strengthening flow out of the southwest.
Expect cautionary level wind to develop by early this evening and
generally persist through Thursday. A period of advisory level winds
and seas will be possible Thursday night into Friday ahead of an
approaching cold front. Advisory level winds will then shift to the
northwest and north in the wake of this front later Friday into
Friday night.
&&
.AVIATION (Through 12Z Thursday)...
Dense fog and IFR Cigs have
developed at area terminals. Conditions will slowly improve after
sunrise this morning with a possible brief period of VFR this
afternoon. Showers and isolated thunderstorms are expected
by this afternoon, especially at Florida terminals. IFR conditions
will likely redevelop this evening and continue through the
overnight hours.
&&
.FIRE WEATHER...
Low level moisture will remain abundant across the region through
Friday ahead of an approaching front. A drier airmass will move in
during the weekend with RH values dropping into the lower 30s.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 71 59 76 64 72 / 70 40 20 20 70
Panama City 68 61 71 65 68 / 70 30 20 30 60
Dothan 72 57 79 64 67 / 60 20 20 50 60
Albany 71 57 79 65 70 / 40 20 20 40 70
Valdosta 71 60 79 64 74 / 50 50 20 20 60
Cross City 72 61 76 63 76 / 50 60 20 10 50
Apalachicola 67 62 70 65 69 / 70 40 10 20 60
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...Dense Fog Advisory until 8 AM CST this morning for Geneva-
Houston.
GA...Dense Fog Advisory until 9 AM EST this morning for Baker-Ben
Hill-Calhoun-Colquitt-Decatur-Dougherty-Early-Grady-Irwin-
Lee-Miller-Mitchell-Seminole-Terrell-Thomas-Tift-Turner-
Worth.
FL...Dense Fog Advisory until 9 AM EST /8 AM CST/ this morning for
Calhoun-Central Walton-Coastal Bay-Coastal Franklin-Coastal
Gulf-Gadsden-Holmes-Inland Bay-Inland Franklin-Inland Gulf-
Inland Wakulla-Inland Walton-Jackson-Leon-Liberty-South
Walton-Washington.
GM...None.
&&
$$
Update/Synopsis/Short Term/Marine...Mroczka
Long term/Aviation/Fire Wx...Camp
AREA FORECAST DISCUSSION...UPDATED
NWS DES MOINES IA
540 AM CST WED FEB 22 2012
.UPDATED 22/12Z AVIATION DISCUSSION...
.SHORT TERM /TODAY/...
TODAYS FORECAST IS RATHER COMPLEX AND IT DOESNT HELP THAT THE
MODELS ARE NOT HANDLING THE FINE DETAILS WELL AT ALL. A PRETTY WEAK
VORT MAX MOVED ACROSS THE FORECAST AREA DURING THE OVERNIGHT AND
THAT WAS ENOUGH TO PRODUCE SOME VERY LIGHT RAIN AND AREAS OF
DRIZZLE. CLEARLY THERE IS MORE MOISTURE IN THE ATMOSPHERE THAN THE
MODELS ARE SUGGESTING. LOOKING UPSTREAM ON WATER VAPOR OVERLAID
WITH RUC 500MB VORTICITY...THERE IS ANOTHER VORT MAX PROGGED TO PUSH
ACROSS THE FORECAST AREA BETWEEN 12 AND 15Z. NAM12 TIME HEIGHT
CROSS SECTIONS SHOW THE WEAK LIFT COMING ACROSS AREA HOWEVER IT
SHOWS SOME DRY LOW LEVEL AIR. HOWEVER...IT DID A POOR JOB WITH
MOISTURE WITH THE LAST VORT MAX SO I HAVE TO BELIEVE IT IS NOT
CAPTURING THE DEPTH OF MOISTURE WELL FOR THIS NEXT SHOT. FOR THAT
REASON I HAVE PUT A SLIGHT CHANCE OF RAIN WITH AREAS OF DRIZZLE
ALONG THE EXPECTED PATH OF THIS NEXT VORT MAX.
TAKING A LOOK AT TEMPS...THEY ARE ALL OVER THE PLACE. IN PART DUE
TO CLOUD COVER AND IN PART DUE TO SOME LOW LEVEL WINDS THAT ARE MORE
SOUTH SOUTHWEST THAN WEST. THE PROBLEM IS THAT TEMPS CURRENTLY ARE
HOVERING RIGHT AT OR JUST BELOW FREEZING. I EXPECT LITTLE TEMP
CHANGE BETWEEN NOW AND 12-13Z OR MAYBE A DROP OF A DEGREE OR TWO.
WITH MOISTURE IN PLACE AND WEAK LIFT AND TEMPS HOVERING AT OR JUST
BELOW FREEZING I HAD TO PUT A MENTION OF FREEZING DRIZZLE IN THE
FORECAST ON THE NORTHERN FRINGE OF THE PATH OF THE NEXT SHOT OF
VORTICITY COMING AT US. I EXPECT THIS ALL TO OCCUR THIS MORNING
YET.
FOR THE REST OF TODAY WE ARE SORT OF IN LIMBO WAITING FOR THE NEXT
SYSTEM TO MOVE IN TONIGHT. I EXPECT TO SEE A FAIR AMOUNT OF MID AND
HIGH LEVEL CLOUD COVER TODAY THEN GRADUALLY MOISTENING UP AS THE
AFTERNOON PROGRESSES. AT THIS POINT I REALLY DON/T SEE MUCH IN THE
WAY OF PRECIP FOR THE AFTERNOON BUT AS MOISTEN UP AHEAD OF THE
SYSTEM TONIGHT...I THINK WE WILL SEE SOME DRIZZLE ACROSS THE AREA.
FOR NOW I JUST HAVE IT ACROSS THE NORTH BUT POTENTIALLY COULD BE
MORE WIDESPREAD THAN THAT. SHOULD BE A FAIRLY MILD DAY AS WE MIX
SOME OF THE WARMER AIR ALOFT DOWN. I WENT A LITTLE AGGRESSIVE ON
THE WARM UP TODAY BUT WE WILL HAVE CLOUD COVER TODAY WHICH WILL
IMPACT THE WARM UP. IF WE HAVE A LOWER CLOUD DECK THAN WHAT I AM
THINKING THEN WE MAY BE TOO WARM. WE WILL NEED TO WATCH THAT.
.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
COMPLICATED FORECAST THIS EXTENDED PERIOD. A NUMBER OF FAST MOVING
WAVES IMPACTING THE REGION OVER THE NEXT 24 HOURS AND LITTLE MODEL
CONSENSUS ON TRACK AND PLACEMENT OF FEATURES. MODELS HAVING A
DIFFICULT TIME RESOLVING THE ENERGY AND THIS WILL MOST LIKELY RESULT
IN FURTHER REFINEMENT IN THE NEXT 1 TO 2 PACKAGES. FIRST WAVE
EXPECTED TO ARRIVE TONIGHT. NAM/GFS CONTINUE TO SHOW A MORE
NORTHERLY SOLUTION OVER NORTHERN IOWA FOR THE FIRST WAVE WHILE THE
GEM/EURO ARE TAKING THE ENERGY FARTHER SOUTH AND ACROSS NORTHERN
MISSOURI. WITH SOME COORDINATION CHALLENGES...HAVE OPTED TO BROAD
BRUSH THE REGION WITH CHANCE POPS...BUT WOULD HAVE PREFERRED TO
FOCUS MORE ON THE SOUTH FOR THE FIRST WAVE. THERMAL PROFILES AND SFC
TEMPERATURES POINT TO MOSTLY LIGHT SNOW NORTH AND A RAIN SNOW MIX
CENTRAL WITH SHOWERS SOUTH HALF. WITH THE SECOND AND STRONGER WAVE
IMPACTING THE AREA ON THURSDAY WHICH DEEPENS AND SLOWS AS IT CROSSES
THE REGION. THE AREA OF WARM AIR ADVECTION ALONG AND AHEAD OF IT IS
ALSO ACCOMPANIED BY AN AREA OF WEAK STABILITY...AND NEGATIVE EPV.
THOUGH IT LOOKS VERY PROBABLE THAT THE PRECIPITATION MAY BE
ACCOMPANIED BY THUNDER...THE LACK OF ANY CONSISTENCY IN TRACK THIS
MORNING MAKES IT DIFFICULT TO PLACE WHERE THIS MIGHT OCCUR. FOR
NOW...HAVE LEFT THE MENTION OUT OF THE FORECAST SO THE AREA CAN BE
BETTER REFINED LATER TODAY. NONE THE LESS...THE AREA WITH GREATER
LIFT IS LIKELY TO SEE SNOW OVERTAKE THE RAIN/SNOW MIX AS CONVECTION
ENHANCES THE PRODUCTION OF SNOW OVER RAIN SHOWERS. CURRENTLY AM
GOING TO GO WITH AN AREA BOUNDED BY JUST SOUTH OF I80 IN THE SOUTH
AND NEAR HIGHWAY 20 IN THE NORTH. WITH THE MIX MOST LIKELY FROM US
30 NORTH...THE HEAVIER SNOWFALL IS MAINLY EXPECTED BETWEEN US 30 AND
US 20 WHERE A BAND OF 1-3 MAY FALL. THIS BEARS WATCHING CLOSELY AND
WILL CAUTION ONCOMING SHIFT THAT FURTHER REFINEMENTS AND DETAIL WILL
BE NEEDED. NO HEADLINES PLANNED RIGHT NOW...AND WILL LET THE NEXT
SHIFT WORK THROUGH THE POSSIBILITY OF HEAVIER SNOW...IF THE NEWER
MODEL RUNS SHOW MORE CONSENSUS. AS THE LOW DEEPENS OVER THE
REGION...A SECONDARY H500 LOW WILL EXTEND BACK INTO CENTRAL IOWA
THURSDAY NIGHT AND LIKELY DROP ANOTHER 1 TO 2 INCHES OF SNOW OVER
THE NORTHEAST THIRD OF THE FORECAST AREA. PLAYING IT CONSERVATIVE
FOR NOW...DUE TO UNCERTAINTY WITH THE MODELS. COLD AIR AND LIGHT
SNOW AND FLURRIES WILL CONTINUE ON FRIDAY WITH LIGHT ACCUMULATIONS
POSSIBLE. BY SATURDAY A RIDGE WILL REPLACE THIS FIRST BATCH OF
ENERGY PRIOR TO THE LARGER SYSTEM APPROACHING FOR SUNDAY/MONDAY.
MODELS CONTINUE TO SHOW LITTLE OVERALL CONSENSUS YET...THOUGH THE
GEM/EURO HAVE SHOWN CONSISTENCY BETWEEN THESE TWO MODELS THE PAST
FEW RUNS. THE GFS IS STILL MUCH DEEPER...EARLIER...AND MAY BE TOO
QUICK TO ADVANCE THE ENERGY EAST AND WIND UP THE LOW. WITH THAT IN
MIND...HAVE BEEN LEANING TOWARD A WARMER SOLUTION FOR SUNDAY WITH
COORDINATION OF SURROUNDING OFFICES AND FAVORING RAIN SHOWERS FOR
NOW. STRONG COLD FRONT AND SNOW CHANCES RETURN SUNDAY NIGHT AS COLD
AIR WRAPS INTO THE SYSTEM. THE REAL SNOW SHOULD FALL WELL NORTHWEST
OF US IN THE DAKOTAS AND MINNESOTA BASED ON ALL THREE MED RANGE
MODELS WHICH ARE NOW BACKING THE LOW NORTHWEST WITH TIME. MUCH
COLDER AIR RETURNS FOR MONDAY AND TUESDAY WITH SOME RECOVERY BY
WEDNESDAY.
&&
.AVIATION DISCUSSION...22/12Z
A COUPLE OF UPPER LEVEL DISTURBANCES WILL PASS ACROSS THE TAF
LOCATIONS THROUGH THE FORECAST PERIOD. ONE DISTURBANCE WILL MOVE
THROUGH BY 18Z. THIS WILL BRING A POTENTIAL FOR LIGHT RAIN OR
DRIZZLE TO KDSM AND KOTM WITH PATCHY FREEZING DRIZZLE OR LIGHT SNOW
TO KALO AND KMCW WITH MAINLY DRIZZLE AND FOG ELSEWHERE. THE NEXT
DISTURBANCE WILL COME TONIGHT PRODUCING MVFR CIGS AND RAIN ACROSS
THE SOUTH WITH SNOW ACROSS THE NORTH.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...FAB
LONG TERM...REV
AVIATION...FAB
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
853 AM EST WED FEB 22 2012
.SYNOPSIS...
WEAK LOW PRESSURE, COMING EAST FROM ILLINOIS, WILL BRING SHOWERS
LATER TODAY AND TONIGHT. A STRONG LOW PRESSURE SYSTEM, COMING
EAST FROM COLORADO, WILL BRING ADDITIONAL SHOWERS THURSDAY INTO
FRIDAY, FOLLOWED BY A COOL DOWN TO SEASONABLE TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
PER BLEND OF RECENT SURFACE, RADAR, AND SATELLITE DATA, COUPLED
WITH RECENT HRRR AND NAM MODEL OUTPUT, HAVE TWEAKED COVERAGE OF
CLOUDS AND SHOWERS INTO THE AFTERNOON. FORECASTED AFTERNOON HIGH
TEMPERATURES CLOSE TO BLEND OF RECENT GFS AND NAM MOS. SURFACE
WINDS CAN GUST TO 25-30 MPH.
AS LOW PRESSURE, COMING EAST FROM ILLINOIS, PASSED THROUGH THE
UPPER OHIO VALLEY TONIGHT, SHOWERS WILL BECOME LIKELY.
ACCOMPANYING CLOUDS WILL HELP KEEP LOW TEMPERATURES MORE THAN 10
DEGREES WARMER THAN NORMAL.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
GFS/NAM SUPPORT THE FRONTAL BOUNDARY STALLING ACROSS THE AREA ON
THURSDAY WITH A FEW RIPPLES IN THE MID-LEVEL FLOW SERVING TO KEEP
CHANCE POPS IN THE FORECAST THROUGH THE DAY. POPS WILL INCREASE LATE
IN THE DAY ON THURSDAY AS A SURFACE LOW DEVELOPS IN THE OHIO VALLEY.
THURSDAY WILL BE THE WARMEST DAY OF THE WEEK, MOST NOTICEABLY FOR
LOCATIONS SOUTH OF THE BOUNDARY. TEMPS WILL WARM TO AROUND 15
DEGREES ABOVE NORMAL WITH IT NOT OUT OF THE QUESTION THAT SOME
LOCATIONS WILL REACH THE 60S.
THE SURFACE LOW WILL CROSS THE AREA THURSDAY NIGHT WITH A MORE
VIGOROUS SHORT WAVE MOVING ACROSS THE EASTERN GREAT LAKES ON FRIDAY.
A STRONG COLD FRONT WILL CROSS EARLY FRIDAY, WITH LIKELY
POPS UNTIL ITS PASSAGE. IN THE WAKE OF THE FRONT, COLD AIR ADVECTION
WILL KICK IN WITH PRECIPITATION BEGINNING TO CHANGE OVER TO SNOW
NORTH OF PITTSBURGH LATE IN THE DAY AS THICKNESSES DECREASE. 850MB
TEMPS WILL ONLY COOL TO AROUND -8C BY FRIDAY EVENING, SO LAKE EFFECT
SHOULD BE LIMITED. HIGHS ON FRIDAY AROUND 5 DEGREES ABOVE NORMAL
WILL LIKELY BE REACHED IN THE MORNING HOURS BEFORE COLDER AND
MORE SEASONABLE AIR IS ADVECTED INTO THE AREA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
PER RECENT HPC-PREFERRED ECMWF MODEL GUIDANCE, EXPECT POST SYSTEM
COOL DOWN TO PROVIDE A MIX WITH SNOW SHOWERS FRIDAY NIGHT AND
SATURDAY. ENSUING HIGH PRESSURE WILL PROVIDE A DRY BREAK SUNDAY INTO
MONDAY.
WITH THE UPPER LEVEL JETSTREAM ORIENTATION BECOMING MORE SOUTHWEST,
A LOW PRESSURE SYSTEM, DEVELOPING ACROSS THE SOUTHERN PLAINS SUNDAY,
WILL MOVE NORTHEAST TO NEW YORK STATE EARLY TUESDAY. HENCE EXPECT A
MIX OF RAIN AND SNOW SHOWERS ACROSS THE UPPER OHIO VALLEY MONDAY
NIGHT AND TUESDAY.
FORECASTED HIGH TEMPERATURES TO BE ABOUT 5 DEGREES COLDER THAN
NORMAL SATURDAY. LOWS SATURDAY NIGHT CAN BE CLOSER TO NORMAL,
DEPENDING ON EXTENT OF LINGERING CLOUDS.
TEMPERATURES SHOULD REBOUND TO NEAR NORMAL LEVEL SUNDAY AND UP TO
ABOUT 5 DEGREES WARMER THAN NORMAL MONDAY INTO TUESDAY.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
PER BLEND OF RECENT SURFACE, RADAR, AND SATELLITE DATA, COUPLED
WITH RECENT HRRR AND NAM MODEL OUTPUT, EXPECT VFR TODAY WITH
CLOUD CEILINGS NO LOWER THAN 5 KFT AGL, EXCEPT IN SCATTERED
SHOWERS WHERE CEILINGS MAY LOWER TO NEAR MVFR LEVELS. SURFACE
WINDS CAN GUST TO 20 KTS.
WITH LOW PRESSURE COMING EAST FROM ILLINOIS, EXPECT NUMEROUS MVFR
SHOWERS TO SPREAD WEST TO EAST ACROSS THE UPPER OHIO VALLEY AFTER
21Z.
OUTLOOK...THURSDAY THROUGH SUNDAY...
A PROLONGED PERIOD OF RESTRICTIONS POSSIBLE WITH RAIN SHOWERS
THURSDAY INTO FRIDAY, WITH PASSAGE OF STRONG LOW PRESSURE SYSTEM,
FOLLOWED BY POST-SYSTEM COLD POOL LOW CLOUDS AND SCATTERED SNOW
SHOWERS FRIDAY NIGHT INTO SATURDAY. HIGH PRESSURE SHOULD RESTORE
VFR SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1221 PM CST WED FEB 22 2012
.UPDATE...
MODELS...ESPECIALLY THE GFS CONTINUE TO SHOW A SIGNIFCANT SHIFT
WITH UPCOMING SYSTEM WITH LARGE IMPACTS FOR THE FORECAST AREA. NAM
CONTINUES TO BE FARTHER NORTH WITH THE EURO SOLUTION FARTHER
SOUTH. GFS IS FOR NOW SPLITTING THE DIFFERENCE AND ANTICIPATING
THE ARRIVAL OF THE 12Z EURO SHORTLY. STRONG FORCING WILL BEGIN
OVERNIGHT AS WARM ADVECTION INCREASES WITH STRONG MID LEVEL
FRONTOGENSIS CONTINUING INTO NORTHERN IOWA ON THURSDAY. SOME
INSTABILITY IS ALSO PRESENT IN THE CROSS SECTIONS AND MAY SEE
BANDED SNOWFALL WITH MOST LIKELY TIME FRAME FROM TOWARD SUNRISE ON
THURSDAY MORNING INTO MIDDAY THURSDAY. HAVE GONE AHEAD WITH WINTER
STORM WATCH ACROSS NORTHERN IOWA...ALONG AND NORTH OF AN TAMA-
WESTER CITY TO POCAHONTAS LINE FROM 09Z TONIGHT THROUGH THE DAY ON
THURSDAY. AMOUNTS AT THIS TIME LOOK TO BE 4 TO 8 INCHES WITH
HIGHEST AMOUNTS NEAR THE MINNESOTA BORDER. IF BANDING DOES
OCCUR...HEAVY AMOUNTS WILL LIKELY RESULT. THERE WILL LIKELY BE A
SHARP GRADIENT ON THE SOUTHERN EDGE OF THE SNOWFALL THEREFORE HAVE
BEEN SOMEWHAT LIBERAL ON INCLUDING COUNTIES ON SOUTHERN EDGE OF
THE WATCH AS MODELS STILL QUITE SPREAD ON THEIR SOLUTIONS.
&&
.PREV DISCUSSION... /ISSUED 540 AM CST WED FEB 22 2012/
UPDATED 22/12Z AVIATION DISCUSSION...
SHORT TERM /TODAY/...
TODAYS FORECAST IS RATHER COMPLEX AND IT DOESNT HELP THAT THE
MODELS ARE NOT HANDLING THE FINE DETAILS WELL AT ALL. A PRETTY WEAK
VORT MAX MOVED ACROSS THE FORECAST AREA DURING THE OVERNIGHT AND
THAT WAS ENOUGH TO PRODUCE SOME VERY LIGHT RAIN AND AREAS OF
DRIZZLE. CLEARLY THERE IS MORE MOISTURE IN THE ATMOSPHERE THAN THE
MODELS ARE SUGGESTING. LOOKING UPSTREAM ON WATER VAPOR OVERLAID
WITH RUC 500MB VORTICITY...THERE IS ANOTHER VORT MAX PROGGED TO PUSH
ACROSS THE FORECAST AREA BETWEEN 12 AND 15Z. NAM12 TIME HEIGHT
CROSS SECTIONS SHOW THE WEAK LIFT COMING ACROSS AREA HOWEVER IT
SHOWS SOME DRY LOW LEVEL AIR. HOWEVER...IT DID A POOR JOB WITH
MOISTURE WITH THE LAST VORT MAX SO I HAVE TO BELIEVE IT IS NOT
CAPTURING THE DEPTH OF MOISTURE WELL FOR THIS NEXT SHOT. FOR THAT
REASON I HAVE PUT A SLIGHT CHANCE OF RAIN WITH AREAS OF DRIZZLE
ALONG THE EXPECTED PATH OF THIS NEXT VORT MAX.
TAKING A LOOK AT TEMPS...THEY ARE ALL OVER THE PLACE. IN PART DUE
TO CLOUD COVER AND IN PART DUE TO SOME LOW LEVEL WINDS THAT ARE MORE
SOUTH SOUTHWEST THAN WEST. THE PROBLEM IS THAT TEMPS CURRENTLY ARE
HOVERING RIGHT AT OR JUST BELOW FREEZING. I EXPECT LITTLE TEMP
CHANGE BETWEEN NOW AND 12-13Z OR MAYBE A DROP OF A DEGREE OR TWO.
WITH MOISTURE IN PLACE AND WEAK LIFT AND TEMPS HOVERING AT OR JUST
BELOW FREEZING I HAD TO PUT A MENTION OF FREEZING DRIZZLE IN THE
FORECAST ON THE NORTHERN FRINGE OF THE PATH OF THE NEXT SHOT OF
VORTICITY COMING AT US. I EXPECT THIS ALL TO OCCUR THIS MORNING
YET.
FOR THE REST OF TODAY WE ARE SORT OF IN LIMBO WAITING FOR THE NEXT
SYSTEM TO MOVE IN TONIGHT. I EXPECT TO SEE A FAIR AMOUNT OF MID AND
HIGH LEVEL CLOUD COVER TODAY THEN GRADUALLY MOISTENING UP AS THE
AFTERNOON PROGRESSES. AT THIS POINT I REALLY DON/T SEE MUCH IN THE
WAY OF PRECIP FOR THE AFTERNOON BUT AS MOISTEN UP AHEAD OF THE
SYSTEM TONIGHT...I THINK WE WILL SEE SOME DRIZZLE ACROSS THE AREA.
FOR NOW I JUST HAVE IT ACROSS THE NORTH BUT POTENTIALLY COULD BE
MORE WIDESPREAD THAN THAT. SHOULD BE A FAIRLY MILD DAY AS WE MIX
SOME OF THE WARMER AIR ALOFT DOWN. I WENT A LITTLE AGGRESSIVE ON
THE WARM UP TODAY BUT WE WILL HAVE CLOUD COVER TODAY WHICH WILL
IMPACT THE WARM UP. IF WE HAVE A LOWER CLOUD DECK THAN WHAT I AM
THINKING THEN WE MAY BE TOO WARM. WE WILL NEED TO WATCH THAT.
LONG TERM /TONIGHT THROUGH WEDNESDAY/...
COMPLICATED FORECAST THIS EXTENDED PERIOD. A NUMBER OF FAST MOVING
WAVES IMPACTING THE REGION OVER THE NEXT 24 HOURS AND LITTLE MODEL
CONSENSUS ON TRACK AND PLACEMENT OF FEATURES. MODELS HAVING A
DIFFICULT TIME RESOLVING THE ENERGY AND THIS WILL MOST LIKELY RESULT
IN FURTHER REFINEMENT IN THE NEXT 1 TO 2 PACKAGES. FIRST WAVE
EXPECTED TO ARRIVE TONIGHT. NAM/GFS CONTINUE TO SHOW A MORE
NORTHERLY SOLUTION OVER NORTHERN IOWA FOR THE FIRST WAVE WHILE THE
GEM/EURO ARE TAKING THE ENERGY FARTHER SOUTH AND ACROSS NORTHERN
MISSOURI. WITH SOME COORDINATION CHALLENGES...HAVE OPTED TO BROAD
BRUSH THE REGION WITH CHANCE POPS...BUT WOULD HAVE PREFERRED TO
FOCUS MORE ON THE SOUTH FOR THE FIRST WAVE. THERMAL PROFILES AND SFC
TEMPERATURES POINT TO MOSTLY LIGHT SNOW NORTH AND A RAIN SNOW MIX
CENTRAL WITH SHOWERS SOUTH HALF. WITH THE SECOND AND STRONGER WAVE
IMPACTING THE AREA ON THURSDAY WHICH DEEPENS AND SLOWS AS IT CROSSES
THE REGION. THE AREA OF WARM AIR ADVECTION ALONG AND AHEAD OF IT IS
ALSO ACCOMPANIED BY AN AREA OF WEAK STABILITY...AND NEGATIVE EPV.
THOUGH IT LOOKS VERY PROBABLE THAT THE PRECIPITATION MAY BE
ACCOMPANIED BY THUNDER...THE LACK OF ANY CONSISTENCY IN TRACK THIS
MORNING MAKES IT DIFFICULT TO PLACE WHERE THIS MIGHT OCCUR. FOR
NOW...HAVE LEFT THE MENTION OUT OF THE FORECAST SO THE AREA CAN BE
BETTER REFINED LATER TODAY. NONE THE LESS...THE AREA WITH GREATER
LIFT IS LIKELY TO SEE SNOW OVERTAKE THE RAIN/SNOW MIX AS CONVECTION
ENHANCES THE PRODUCTION OF SNOW OVER RAIN SHOWERS. CURRENTLY AM
GOING TO GO WITH AN AREA BOUNDED BY JUST SOUTH OF I80 IN THE SOUTH
AND NEAR HIGHWAY 20 IN THE NORTH. WITH THE MIX MOST LIKELY FROM US
30 NORTH...THE HEAVIER SNOWFALL IS MAINLY EXPECTED BETWEEN US 30 AND
US 20 WHERE A BAND OF 1-3 MAY FALL. THIS BEARS WATCHING CLOSELY AND
WILL CAUTION ONCOMING SHIFT THAT FURTHER REFINEMENTS AND DETAIL WILL
BE NEEDED. NO HEADLINES PLANNED RIGHT NOW...AND WILL LET THE NEXT
SHIFT WORK THROUGH THE POSSIBILITY OF HEAVIER SNOW...IF THE NEWER
MODEL RUNS SHOW MORE CONSENSUS. AS THE LOW DEEPENS OVER THE
REGION...A SECONDARY H500 LOW WILL EXTEND BACK INTO CENTRAL IOWA
THURSDAY NIGHT AND LIKELY DROP ANOTHER 1 TO 2 INCHES OF SNOW OVER
THE NORTHEAST THIRD OF THE FORECAST AREA. PLAYING IT CONSERVATIVE
FOR NOW...DUE TO UNCERTAINTY WITH THE MODELS. COLD AIR AND LIGHT
SNOW AND FLURRIES WILL CONTINUE ON FRIDAY WITH LIGHT ACCUMULATIONS
POSSIBLE. BY SATURDAY A RIDGE WILL REPLACE THIS FIRST BATCH OF
ENERGY PRIOR TO THE LARGER SYSTEM APPROACHING FOR SUNDAY/MONDAY.
MODELS CONTINUE TO SHOW LITTLE OVERALL CONSENSUS YET...THOUGH THE
GEM/EURO HAVE SHOWN CONSISTENCY BETWEEN THESE TWO MODELS THE PAST
FEW RUNS. THE GFS IS STILL MUCH DEEPER...EARLIER...AND MAY BE TOO
QUICK TO ADVANCE THE ENERGY EAST AND WIND UP THE LOW. WITH THAT IN
MIND...HAVE BEEN LEANING TOWARD A WARMER SOLUTION FOR SUNDAY WITH
COORDINATION OF SURROUNDING OFFICES AND FAVORING RAIN SHOWERS FOR
NOW. STRONG COLD FRONT AND SNOW CHANCES RETURN SUNDAY NIGHT AS COLD
AIR WRAPS INTO THE SYSTEM. THE REAL SNOW SHOULD FALL WELL NORTHWEST
OF US IN THE DAKOTAS AND MINNESOTA BASED ON ALL THREE MED RANGE
MODELS WHICH ARE NOW BACKING THE LOW NORTHWEST WITH TIME. MUCH
COLDER AIR RETURNS FOR MONDAY AND TUESDAY WITH SOME RECOVERY BY
WEDNESDAY.
AVIATION DISCUSSION...22/18Z
RELATIVELY QUIET WEATHER THIS AFTERNOON WITH AS FIRST SHORT WAVE
PULLS TO THE EAST. THEREFORE...GENERALLY VFR CONDITIONS ARE
EXPECTED AT THE TAF SITES. ONLY EXCEPTIONS IS SOME NARROW BAND OF
STRATUS NEAR KMCW. OTHERWISE...WILL SEE INCREASING CLOUDS THIS
EVENING AHEAD OF THE APPROACHING SHORTWAVE WITH PCPN DEVELOPING
TOWARD MIDNIGHT AS WAA INTENSIFIES. RAIN IS EXPECTED PRIMARILY
SOUTH OF KFOD TO KALO LINE WITH RAIN CHANGING TO SNOW FARTHER
NORTH. THE PRECIPITATION WILL PERSIST ACROSS NORTHERN IOWA INTO
THURSDAY MORNING WITH WIDESPREAD IFR CONDITIONS AT KMCW AND
POSSIBLY KFOD AND KALO AS WELL. SURFACE WINDS WILL BECOME
SOUTHEAST TONIGHT SWITCHING TO THE NORTHWEST AND INCREASING ON
THURSDAY MORNING.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH THURSDAY 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 UPDATE...COGIL
.LONG TERM...REV
.AVIATION...COGIL
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1218 PM EST WED FEB 22 2012
.SYNOPSIS...
WEAK LOW PRESSURE, COMING EAST FROM ILLINOIS, WILL BRING SHOWERS
LATER TODAY AND TONIGHT. A STRONG LOW PRESSURE SYSTEM, COMING
EAST FROM COLORADO, WILL BRING ADDITIONAL SHOWERS THURSDAY INTO
FRIDAY, FOLLOWED BY A COOL DOWN TO SEASONABLE TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
MADE UPDATES TO THIS AFTERNOON AND EVENINGS FORECAST BASED OFF OF
THE CURRENT RADAR AND SATELLITE COVERAGE OF PRECIPITATION AND
CLOUD COVER. THE HRRR...RUC...SREF DO NOT BRING PRECIPITATION INTO
OUR COUNTIES UNTIL CLOSE TO 00Z SO HAVE PUSHED BACK TIMING OF POPS
FOR THE OVERNIGHT PERIOD JUST SLIGHTLY.
THE WEAK SURFACE LOW WILL APPROACH TONIGHT AND THE ASSOCIATED
SHORTWAVE DROPPING THROUGH THE BROAD 500MB TROUGH WILL HELP TO
PROGRESS A LINE OF SHOWERS ACROSS THE REGION OVERNIGHT. MAINTAINED
LIKELY POPS FOR PORTIONS OF THE OVERNIGHT AS THE HI-RES MODELS
MAINTAIN A DECENT LINE OF PRECIPITATION ORGANIZING AND REACHING THE
EASTERN ZONES BY 06Z.
AS WAS THE CASE YESTERDAY EVENING...SOME GUSTS COULD APPROACH
25-30MPH THIS AFTERNOON AS SUGGESTED BY THE NAM AND GFS MODEL
PROFILES.
MAINTAINED TEMPERATURES AROUND MAV/MET GUIDANCE WHICH IS ROUGHLY
10 DEGREES ABOVE NORMAL FOR TONIGHT.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
GFS/NAM SUPPORT THE FRONTAL BOUNDARY STALLING ACROSS THE AREA ON
THURSDAY WITH A FEW RIPPLES IN THE MID-LEVEL FLOW SERVING TO KEEP
CHANCE POPS IN THE FORECAST THROUGH THE DAY. POPS WILL INCREASE LATE
IN THE DAY ON THURSDAY AS A SURFACE LOW DEVELOPS IN THE OHIO VALLEY.
THURSDAY WILL BE THE WARMEST DAY OF THE WEEK, MOST NOTICEABLY FOR
LOCATIONS SOUTH OF THE BOUNDARY. TEMPS WILL WARM TO AROUND 15
DEGREES ABOVE NORMAL WITH IT NOT OUT OF THE QUESTION THAT SOME
LOCATIONS WILL REACH THE 60S.
THE SURFACE LOW WILL CROSS THE AREA THURSDAY NIGHT WITH A MORE
VIGOROUS SHORT WAVE MOVING ACROSS THE EASTERN GREAT LAKES ON FRIDAY.
A STRONG COLD FRONT WILL CROSS EARLY FRIDAY, WITH LIKELY
POPS UNTIL ITS PASSAGE. IN THE WAKE OF THE FRONT, COLD AIR ADVECTION
WILL KICK IN WITH PRECIPITATION BEGINNING TO CHANGE OVER TO SNOW
NORTH OF PITTSBURGH LATE IN THE DAY AS THICKNESSES DECREASE. 850MB
TEMPS WILL ONLY COOL TO AROUND -8C BY FRIDAY EVENING, SO LAKE EFFECT
SHOULD BE LIMITED. HIGHS ON FRIDAY AROUND 5 DEGREES ABOVE NORMAL
WILL LIKELY BE REACHED IN THE MORNING HOURS BEFORE COLDER AND
MORE SEASONABLE AIR IS ADVECTED INTO THE AREA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
PER RECENT HPC-PREFERRED ECMWF MODEL GUIDANCE, EXPECT POST SYSTEM
COOL DOWN TO PROVIDE A MIX WITH SNOW SHOWERS FRIDAY NIGHT AND
SATURDAY. ENSUING HIGH PRESSURE WILL PROVIDE A DRY BREAK SUNDAY INTO
MONDAY.
WITH THE UPPER LEVEL JETSTREAM ORIENTATION BECOMING MORE SOUTHWEST,
A LOW PRESSURE SYSTEM, DEVELOPING ACROSS THE SOUTHERN PLAINS SUNDAY,
WILL MOVE NORTHEAST TO NEW YORK STATE EARLY TUESDAY. HENCE EXPECT A
MIX OF RAIN AND SNOW SHOWERS ACROSS THE UPPER OHIO VALLEY MONDAY
NIGHT AND TUESDAY.
FORECASTED HIGH TEMPERATURES TO BE ABOUT 5 DEGREES COLDER THAN
NORMAL SATURDAY. LOWS SATURDAY NIGHT CAN BE CLOSER TO NORMAL,
DEPENDING ON EXTENT OF LINGERING CLOUDS.
TEMPERATURES SHOULD REBOUND TO NEAR NORMAL LEVEL SUNDAY AND UP TO
ABOUT 5 DEGREES WARMER THAN NORMAL MONDAY INTO TUESDAY.
&&
.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
PER BLEND OF RECENT SURFACE, RADAR, AND SATELLITE DATA, COUPLED
WITH RECENT HRRR AND NAM MODEL OUTPUT, EXPECT VFR TODAY WITH
CLOUD CEILINGS NO LOWER THAN 5 KFT AGL, EXCEPT IN SCATTERED
SHOWERS WHERE CEILINGS MAY LOWER TO NEAR MVFR LEVELS. SURFACE
WINDS CAN GUST TO 20 KTS.
WITH LOW PRESSURE COMING EAST FROM ILLINOIS, EXPECT NUMEROUS MVFR
SHOWERS TO SPREAD WEST TO EAST ACROSS THE UPPER OHIO VALLEY AFTER
21Z.
OUTLOOK...THURSDAY THROUGH SUNDAY...
A PROLONGED PERIOD OF RESTRICTIONS POSSIBLE WITH RAIN SHOWERS
THURSDAY INTO FRIDAY, WITH PASSAGE OF STRONG LOW PRESSURE SYSTEM,
FOLLOWED BY POST-SYSTEM COLD POOL LOW CLOUDS AND SCATTERED SNOW
SHOWERS FRIDAY NIGHT INTO SATURDAY. HIGH PRESSURE SHOULD RESTORE
VFR SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
445 PM EST WED FEB 22 2012
.UPDATE...
ISSUED AT 444 PM EST WED FEB 22 2012
WILL BE ISSUING A WINTER STORM WATCH SHORTLY FOR THE CWA FROM
THURSDAY AFTERNOON INTO FRIDAY MORNING BASED LARGELY ON LATEST
ECMWF GUIDANCE. WILL TRY TO HAVE THE WATCH OUT BY 5 PM.
&&
.SYNOPSIS...
ISSUED AT 400 PM EST WED FEB 22 2012
A WEAK SYSTEM WILL MOVE THROUGH THE AREA EARLY TONIGHT BRINGING A
PERIOD OF SNOW SHOWERS TO AREAS NEAR AND SOUTH OF INTERSTATE 96. A
HIGH PRESSURE RIDGE WILL MOVE ACROSS THE AREA DURING THE MID
MORNING HOURS OF THURSDAY BRINGING PARTIAL CLEARING TO THE AREA.
THEN A STORM DEVELOPING IN THE SOUTHERN PLAINS WILL HEAD TO THE
SOUTH CENTRAL GREAT LAKES FOR LATE THURSDAY NIGHT AND HEAD INTO
NEW ENGLAND FRIDAY. THAT WILL BRING A PERIOD OF SIGNIFICANT
SNOWFALL TO THE AREA THURSDAY NIGHT INTO FRIDAY. SOME LAKE EFFECT
SNOW IS EXPECTED INTO SATURDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 400 PM EST WED FEB 22 2012
THERE IS THE THREAT FOR A SIGNIFICANT SNOWFALL EVENT THURSDAY
NIGHT INTO FRIDAY. CURRENT THINKING IS 4 TO 7 INCHES OVER THE
CENTRAL CWA... NEAR INTERSTATE 96. MOST OF THE SNOW SHOULD FALL
DURING THE MID TO LATE EVENING HOURS OF THURSDAY NIGHT INTO THE
MID MORNING HOURS OF FRIDAY.
THERE IS ALSO THE THREAT FOR A BRIEF BURST OF SIGNIFICANT SNOW THIS
EVENING AS A SHORTWAVE OVER WISCONSIN HEADS EAST ACROSS LAKE
MICHIGAN AND INTENSIFIES THIS EVENING. BOTH THE HRRR SUGGESTS UP
TO .25 INCHES OF QPF IN 3 HOURS OVER PARTS OF NORTHERN OTTAWA AND
CENTRAL AND NORTHERN KENT COUNTIES BY BETWEEN 9 PM AND MIDNIGHT.
SINCE THE PRECIPITATION AREA ALREADY IS OVER CENTRAL WISCONSIN AND
IS HEADED EAST... IT WOULD SEEM MORE THAN REASONABLE THIS WOULD
IMPACT CENTRAL LOWER MICHIGAN THIS EVENING. THERE IS GOOD LIFT IN
THE DGZ AS THIS FEATURE MOVES THROUGH THE AREA SO THAT SHOULD HELP
THE SNOWFLAKE PRODUCTION. WITH SURFACE DEW POINTS IN THE MID 20S
THE SNOW WILL WET BULB DOWN THE AIR TEMP QUICKLY SO SNOW WILL REACH
THE GROUND.
ONCE THAT FEATURE MOVES EAST OF THE CWA LATER THIS EVENING SHORT
WAVE RIDGING FOLLOWS LATE TONIGHT INTO MIDDAY THURSDAY. THAT
SHOULD ALLOW THE SKIES TO BECOME PARTLY CLOUDY...AT LEAST FOR A
TIME.
THEN WE HAVE THE ISSUE OF OUR STORM ON THURSDAY NIGHT. THE GFS AND
NAM HAVE BEEN CONSISTENTLY FARTHER NORTH THEN THE ECMWF HAS BEEN
WITH THIS SYSTEM. HOWEVER... THE ECMWF HAS FINALLY SHOWED A
SIGNIFICANT SHIFT NORTHWARD IN THE TRACK OF THE SYSTEM THURSDAY
NIGHT. THE REGIONAL GEM IS FARTHER NORTH AND WEST THAN IS THE
HEMISPHERIC GEM... TRACKING THE LOW NEAR DETROIT LATE THURSDAY
NIGHT. THERE IS SIGNIFICANT FGEN SUPPORT OF THIS EVENT AS IT IS
EXIT REGION OF 165 KNOT 300 MB JET CORE THAT TURNS CYCLONIC AS
IT HEADS NORTHEAST TOWARD CENTRAL OHIO FRIDAY MORNING. THIS ALSO
CREATES QUIET THE TROWAL FEATURE WITH STRONG ISOTROPIC LIFT. THERE
IS 3 TO 4 G/KG OF WATER NEAR 700 MB WHILE THIS IS GOING ON SO
SNOWFALL AMOUNTS OF 3 TO 6 INCHES SHOULD BE EASY TO DO WITH THIS
SET UP.
I WOULD HAVE ISSUED A WINTER STORM WATCH FOR THIS EVENT EXPECT FOR
THE ISSUE OF MODEL UNCERTAINTY. I WILL LET THE MIDNIGHT SHIFT
CONSIDER DOING JUST THAT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 400 PM EST WED FEB 22 2012
UNSETTLED/ACTIVE WEATHER IS EXPECTED TO GENERALLY CONTINUE THROUGH
THE LONG TERM PORTION OF THE FORECAST...IF NOT THE NEXT COUPLE OF
WEEKS. MAIN ITEMS OF CONCERN ARE LINGERING SNOW ON FRI...LAKE EFFECT
FRI NIGHT/SAT...SYSTEM COMING IN LATE SUN THROUGH MON...AND LAKE
EFFECT AGAIN ON TUE.
AN ACTIVE JET STREAM IS EXPECTED TO AFFECT MOST OF THE COUNTRY
THROUGH THE NEXT WEEK. WE ARE EXPECTING TO SEE STRONG PIECES OF
ENERGY BE PUSHED ACROSS THE COUNTRY...FUELED BY A VERY STRONG JET
OVER THE NRN PACIFIC. A LOT OF THIS ENERGY IS EXPECTED TO DIVE SE
INTO THE WRN STATES...BEFORE LIFTING E/NE TOWARD THE GREAT LAKES
REGION.
WE WILL SEE THE FIRST IN THE SERIES OF PV ANOMALIES/WAVES BE MOVING
OUT OF THE AREA AFTER DEPOSITING ACCUMULATING SNOW THU NIGHT AND
INTO FRI. IN THE WAKE OF THIS PHASED UPPER FEATURE...A POOL OF
ARCTIC AIR TO OUR NW WILL BE TAPPED AND WILL PUSH INTO THE AREA.
SYNOPTIC SNOW WILL LIKELY BE ONGOING EARLY ON FRI BEFORE TAPERING
OFF DURING THE DAY. THE SNOW WILL TRANSITION TO SOME LAKE EFFECT AS
H850 TEMPS DROP DOWN TO AROUND -10C TO -12C. WE COULD SEE SOME
DECENT LAKE EFFECT ACCUMS FOR MAINLY NW FAVORED AREAS WITH MOISTURE
POTENTIALLY UP THROUGH 10K FT LATE FRI AND FRI NIGHT. INVERSION
HEIGHTS WILL GRADUALLY FALL THROUGH SAT AS THE UPPER FLOW WILL
TRANSITION TO ANTI-CYCLONIC BY SAT EVENING.
WE WILL SEE A BRIEF BREAK IN THE WEATHER THEN SAT NIGHT THROUGH A
GOOD PORTION OF SUN FOR MOST AREAS AS RIDGING BUILDS IN. NW AREAS
COULD SEE SOME LIGHT PCPN SUN AFTERNOON AS WAA/ISENTROPIC ASCENT
STRENGTHENS AHEAD OF THE NEXT SYSTEM. THE UNSETTLED WEATHER WILL
SPREAD ACROSS THE ENTIRE AREA SUN NIGHT AS THE NEXT STRONG WAVE
DIVING INTO THE SW U.S. EARLY IN THE WEEKEND WILL LIFT NE. THIS WILL
LIKELY TAP SOME WARMER AND MOIST AIR FROM THE GULF AND ADVECT IT
INTO THE AREA LATE SUN THROUGH MON MORNING. PCPN COULD START OFF AS
SNOW...BUT SHOULD CHANGE OVER TO RAIN FOR A PERIOD SUN NIGHT AND
EARLY MON. THUNDER CAN NOT EVEN BE RULED OUT WITH THE STRONG FORCING
ASSOCIATED WITH THE SYSTEM. NOT CONFIDENT ENOUGH YET TO ADD THUNDER
INTO THE FCST.
THE COLD FRONT WILL MOVE THROUGH ON MON...AND A FLOOD OF COLDER AIR
WILL MOVE IN ACROSS THE STATE. THIS WILL HELP TO START THE LAKE
EFFECT BACK UP AS H850 TEMPS DROP BACK DOWN TO AROUND -10C TO -12C.
MODELS ARE INDICATING THOUGH THAT THE LOW LEVEL FLOW WILL TEND TO BE
NE WITH THE WAY THE RIDGE BUILDS IN FROM THE NW. THIS WILL TEND TO
LIMIT THE LAKE EFFECT CHCS AND AMOUNTS. QUITE A BIT OF UNCERTAINTY
WITH REGARDS TO TIMING AND TRACK WITH ANOTHER WAVE THAT IS EXPECTED
TO LIFT OUT FROM THE WRN U.S. BY MID WEEK NEXT WEEK.
&&
.AVIATION...(FOR THE 21Z TAFS THROUGH 21Z THURSDAY AFTERNOON)
ISSUED AT 400 PM EST WED FEB 22 2012
I UPDATED THE TAFS TO ALLOW FOR THE BURST OF SNOW ASSOCIATED WITH
THE SHORTWAVE CROSSING EASTERN WISCONSIN AT 3 PM. THIS SHOULD REACH
THE MKG/GRR TAFS SITES AROUND 03Z AND BE EAST OF THERE BY 06Z. BY
THE TIME IT REACHES LAN AROUND 05Z IT SHOULD WEAKEN. I EXPECT IFR
CIGS/VSBY AS THE SNOW BAND MOVES ACROSS THE I-96 TAFS SITES.
THE I-94 TAF SITES SHOULD SEE MVFR CONDITIONS AS THIS ROLLS
THROUGH. ALL AREAS SHOULD SEE CLEARING TO VFR BY 09Z ONCE THIS
FEATURE HAS EXITED THE AREA.
&&
.MARINE...
ISSUED AT 400 PM EST WED FEB 22 2012
WINDS AND WAVES ARE STILL IN THE SMALL CRAFT ADVISORY RANGE LATE
THIS AFTERNOON. WINDS AND WAVES WILL DIMINISH TONIGHT OVERNIGHT AS
THE SURFACE RIDGE GETS CLOSER TO THE AREA. I WILL LET THE ADVISORY
EXPIRE AS SCHEDUALED.
&&
.HYDROLOGY...
ISSUED AT 400 PM EST WED FEB 22 2012
NO SIGNIFICANT HYDROLOGY ISSUES ARE EXPECTED AS THE PRECIPITATION
THAT FALLS WILL BE IN THE FROM FOR SNOW. NONE OF RIVERS ARE AT OR
ABOVE ACTION STAGE CURRENTLY.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...TJT
SYNOPSIS...TJT
SHORT TERM...WDM
LONG TERM....NJJ
AVIATION...WDM
MARINE...WDM
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
441 PM EST WED FEB 22 2012
.UPDATE...
ISSUED AT 440 PM EST WED FEB 22 2012
WILL BE ISSUING A WINTER STORM WATCH SHORTLY FOR THE CWA FROM
THURSDAY AFTERNOON AND LASTING INTO FRIDAY AFTERNOON. THE REASON
FOR THE LONG DURATION IS TO EMCOMPASS LAKE EFFECT BEHIND THE
STORM. MORE DETAILS ON REASONING TO FOLLOW. WILL TRY TO HAVE THE
WATCH OUT BY 5 PM.
&&
.SYNOPSIS...
ISSUED AT 400 PM EST WED FEB 22 2012
A WEAK SYSTEM WILL MOVE THROUGH THE AREA EARLY TONIGHT BRINGING A
PERIOD OF SNOW SHOWERS TO AREAS NEAR AND SOUTH OF INTERSTATE 96. A
HIGH PRESSURE RIDGE WILL MOVE ACROSS THE AREA DURING THE MID
MORNING HOURS OF THURSDAY BRINGING PARTIAL CLEARING TO THE AREA.
THEN A STORM DEVELOPING IN THE SOUTHERN PLAINS WILL HEAD TO THE
SOUTH CENTRAL GREAT LAKES FOR LATE THURSDAY NIGHT AND HEAD INTO
NEW ENGLAND FRIDAY. THAT WILL BRING A PERIOD OF SIGNIFICANT
SNOWFALL TO THE AREA THURSDAY NIGHT INTO FRIDAY. SOME LAKE EFFECT
SNOW IS EXPECTED INTO SATURDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 400 PM EST WED FEB 22 2012
THERE IS THE THREAT FOR A SIGNIFICANT SNOWFALL EVENT THURSDAY
NIGHT INTO FRIDAY. CURRENT THINKING IS 4 TO 7 INCHES OVER THE
CENTRAL CWA... NEAR INTERSTATE 96. MOST OF THE SNOW SHOULD FALL
DURING THE MID TO LATE EVENING HOURS OF THURSDAY NIGHT INTO THE
MID MORNING HOURS OF FRIDAY.
THERE IS ALSO THE THREAT FOR A BRIEF BURST OF SIGNIFICANT SNOW THIS
EVENING AS A SHORTWAVE OVER WISCONSIN HEADS EAST ACROSS LAKE
MICHIGAN AND INTENSIFIES THIS EVENING. BOTH THE HRRR SUGGESTS UP
TO .25 INCHES OF QPF IN 3 HOURS OVER PARTS OF NORTHERN OTTAWA AND
CENTRAL AND NORTHERN KENT COUNTIES BY BETWEEN 9 PM AND MIDNIGHT.
SINCE THE PRECIPITATION AREA ALREADY IS OVER CENTRAL WISCONSIN AND
IS HEADED EAST... IT WOULD SEEM MORE THAN REASONABLE THIS WOULD
IMPACT CENTRAL LOWER MICHIGAN THIS EVENING. THERE IS GOOD LIFT IN
THE DGZ AS THIS FEATURE MOVES THROUGH THE AREA SO THAT SHOULD HELP
THE SNOWFLAKE PRODUCTION. WITH SURFACE DEW POINTS IN THE MID 20S
THE SNOW WILL WET BULB DOWN THE AIR TEMP QUICKLY SO SNOW WILL REACH
THE GROUND.
ONCE THAT FEATURE MOVES EAST OF THE CWA LATER THIS EVENING SHORT
WAVE RIDGING FOLLOWS LATE TONIGHT INTO MIDDAY THURSDAY. THAT
SHOULD ALLOW THE SKIES TO BECOME PARTLY CLOUDY...AT LEAST FOR A
TIME.
THEN WE HAVE THE ISSUE OF OUR STORM ON THURSDAY NIGHT. THE GFS AND
NAM HAVE BEEN CONSISTENTLY FARTHER NORTH THEN THE ECMWF HAS BEEN
WITH THIS SYSTEM. HOWEVER... THE ECMWF HAS FINALLY SHOWED A
SIGNIFICANT SHIFT NORTHWARD IN THE TRACK OF THE SYSTEM THURSDAY
NIGHT. THE REGIONAL GEM IS FARTHER NORTH AND WEST THAN IS THE
HEMISPHERIC GEM... TRACKING THE LOW NEAR DETROIT LATE THURSDAY
NIGHT. THERE IS SIGNIFICANT FGEN SUPPORT OF THIS EVENT AS IT IS
EXIT REGION OF 165 KNOT 300 MB JET CORE THAT TURNS CYCLONIC AS
IT HEADS NORTHEAST TOWARD CENTRAL OHIO FRIDAY MORNING. THIS ALSO
CREATES QUIET THE TROWAL FEATURE WITH STRONG ISOTROPIC LIFT. THERE
IS 3 TO 4 G/KG OF WATER NEAR 700 MB WHILE THIS IS GOING ON SO
SNOWFALL AMOUNTS OF 3 TO 6 INCHES SHOULD BE EASY TO DO WITH THIS
SET UP.
I WOULD HAVE ISSUED A WINTER STORM WATCH FOR THIS EVENT EXPECT FOR
THE ISSUE OF MODEL UNCERTAINTY. I WILL LET THE MIDNIGHT SHIFT
CONSIDER DOING JUST THAT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 400 PM EST WED FEB 22 2012
UNSETTLED/ACTIVE WEATHER IS EXPECTED TO GENERALLY CONTINUE THROUGH
THE LONG TERM PORTION OF THE FORECAST...IF NOT THE NEXT COUPLE OF
WEEKS. MAIN ITEMS OF CONCERN ARE LINGERING SNOW ON FRI...LAKE EFFECT
FRI NIGHT/SAT...SYSTEM COMING IN LATE SUN THROUGH MON...AND LAKE
EFFECT AGAIN ON TUE.
AN ACTIVE JET STREAM IS EXPECTED TO AFFECT MOST OF THE COUNTRY
THROUGH THE NEXT WEEK. WE ARE EXPECTING TO SEE STRONG PIECES OF
ENERGY BE PUSHED ACROSS THE COUNTRY...FUELED BY A VERY STRONG JET
OVER THE NRN PACIFIC. A LOT OF THIS ENERGY IS EXPECTED TO DIVE SE
INTO THE WRN STATES...BEFORE LIFTING E/NE TOWARD THE GREAT LAKES
REGION.
WE WILL SEE THE FIRST IN THE SERIES OF PV ANOMALIES/WAVES BE MOVING
OUT OF THE AREA AFTER DEPOSITING ACCUMULATING SNOW THU NIGHT AND
INTO FRI. IN THE WAKE OF THIS PHASED UPPER FEATURE...A POOL OF
ARCTIC AIR TO OUR NW WILL BE TAPPED AND WILL PUSH INTO THE AREA.
SYNOPTIC SNOW WILL LIKELY BE ONGOING EARLY ON FRI BEFORE TAPERING
OFF DURING THE DAY. THE SNOW WILL TRANSITION TO SOME LAKE EFFECT AS
H850 TEMPS DROP DOWN TO AROUND -10C TO -12C. WE COULD SEE SOME
DECENT LAKE EFFECT ACCUMS FOR MAINLY NW FAVORED AREAS WITH MOISTURE
POTENTIALLY UP THROUGH 10K FT LATE FRI AND FRI NIGHT. INVERSION
HEIGHTS WILL GRADUALLY FALL THROUGH SAT AS THE UPPER FLOW WILL
TRANSITION TO ANTI-CYCLONIC BY SAT EVENING.
WE WILL SEE A BRIEF BREAK IN THE WEATHER THEN SAT NIGHT THROUGH A
GOOD PORTION OF SUN FOR MOST AREAS AS RIDGING BUILDS IN. NW AREAS
COULD SEE SOME LIGHT PCPN SUN AFTERNOON AS WAA/ISENTROPIC ASCENT
STRENGTHENS AHEAD OF THE NEXT SYSTEM. THE UNSETTLED WEATHER WILL
SPREAD ACROSS THE ENTIRE AREA SUN NIGHT AS THE NEXT STRONG WAVE
DIVING INTO THE SW U.S. EARLY IN THE WEEKEND WILL LIFT NE. THIS WILL
LIKELY TAP SOME WARMER AND MOIST AIR FROM THE GULF AND ADVECT IT
INTO THE AREA LATE SUN THROUGH MON MORNING. PCPN COULD START OFF AS
SNOW...BUT SHOULD CHANGE OVER TO RAIN FOR A PERIOD SUN NIGHT AND
EARLY MON. THUNDER CAN NOT EVEN BE RULED OUT WITH THE STRONG FORCING
ASSOCIATED WITH THE SYSTEM. NOT CONFIDENT ENOUGH YET TO ADD THUNDER
INTO THE FCST.
THE COLD FRONT WILL MOVE THROUGH ON MON...AND A FLOOD OF COLDER AIR
WILL MOVE IN ACROSS THE STATE. THIS WILL HELP TO START THE LAKE
EFFECT BACK UP AS H850 TEMPS DROP BACK DOWN TO AROUND -10C TO -12C.
MODELS ARE INDICATING THOUGH THAT THE LOW LEVEL FLOW WILL TEND TO BE
NE WITH THE WAY THE RIDGE BUILDS IN FROM THE NW. THIS WILL TEND TO
LIMIT THE LAKE EFFECT CHCS AND AMOUNTS. QUITE A BIT OF UNCERTAINTY
WITH REGARDS TO TIMING AND TRACK WITH ANOTHER WAVE THAT IS EXPECTED
TO LIFT OUT FROM THE WRN U.S. BY MID WEEK NEXT WEEK.
&&
.AVIATION...(FOR THE 21Z TAFS THROUGH 21Z THURSDAY AFTERNOON)
ISSUED AT 400 PM EST WED FEB 22 2012
I UPDATED THE TAFS TO ALLOW FOR THE BURST OF SNOW ASSOCIATED WITH
THE SHORTWAVE CROSSING EASTERN WISCONSIN AT 3 PM. THIS SHOULD REACH
THE MKG/GRR TAFS SITES AROUND 03Z AND BE EAST OF THERE BY 06Z. BY
THE TIME IT REACHES LAN AROUND 05Z IT SHOULD WEAKEN. I EXPECT IFR
CIGS/VSBY AS THE SNOW BAND MOVES ACROSS THE I-96 TAFS SITES.
THE I-94 TAF SITES SHOULD SEE MVFR CONDITIONS AS THIS ROLLS
THROUGH. ALL AREAS SHOULD SEE CLEARING TO VFR BY 09Z ONCE THIS
FEATURE HAS EXITED THE AREA.
&&
.MARINE...
ISSUED AT 400 PM EST WED FEB 22 2012
WINDS AND WAVES ARE STILL IN THE SMALL CRAFT ADVISORY RANGE LATE
THIS AFTERNOON. WINDS AND WAVES WILL DIMINISH TONIGHT OVERNIGHT AS
THE SURFACE RIDGE GETS CLOSER TO THE AREA. I WILL LET THE ADVISORY
EXPIRE AS SCHEDUALED.
&&
.HYDROLOGY...
ISSUED AT 400 PM EST WED FEB 22 2012
NO SIGNIFICANT HYDROLOGY ISSUES ARE EXPECTED AS THE PRECIPITATION
THAT FALLS WILL BE IN THE FROM FOR SNOW. NONE OF RIVERS ARE AT OR
ABOVE ACTION STAGE CURRENTLY.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...TJT
SYNOPSIS...TJT
SHORT TERM...WDM
LONG TERM....NJJ
AVIATION...WDM
MARINE...WDM
HYDRO...WDM
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
401 PM EST WED FEB 22 2012
.SYNOPSIS...
ISSUED AT 400 PM EST WED FEB 22 2012
A WEAK SYSTEM WILL MOVE THROUGH THE AREA EARLY TONIGHT BRINGING A
PERIOD OF SNOW SHOWERS TO AREAS NEAR AND SOUTH OF INTERSTATE 96. A
HIGH PRESSURE RIDGE WILL MOVE ACROSS THE AREA DURING THE MID
MORNING HOURS OF THURSDAY BRINGING PARTIAL CLEARING TO THE AREA.
THEN A STORM DEVELOPING IN THE SOUTHERN PLAINS WILL HEAD TO THE
SOUTH CENTRAL GREAT LAKES FOR LATE THURSDAY NIGHT AND HEAD INTO
NEW ENGLAND FRIDAY. THAT WILL BRING A PERIOD OF SIGNIFICANT
SNOWFALL TO THE AREA THURSDAY NIGHT INTO FRIDAY. SOME LAKE EFFECT
SNOW IS EXPECTED INTO SATURDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 400 PM EST WED FEB 22 2012
THERE IS THE THREAT FOR A SIGNIFICANT SNOWFALL EVENT THURSDAY
NIGHT INTO FRIDAY. CURRENT THINKING IS 4 TO 7 INCHES OVER THE
CENTRAL CWA... NEAR INTERSTATE 96. MOST OF THE SNOW SHOULD FALL
DURING THE MID TO LATE EVENING HOURS OF THURSDAY NIGHT INTO THE
MID MORNING HOURS OF FRIDAY.
THERE IS ALSO THE THREAT FOR A BRIEF BURST OF SIGNIFICANT SNOW THIS
EVENING AS A SHORTWAVE OVER WISCONSIN HEADS EAST ACROSS LAKE
MICHIGAN AND INTENSIFIES THIS EVENING. BOTH THE HRRR SUGGESTS UP
TO .25 INCHES OF QPF IN 3 HOURS OVER PARTS OF NORTHERN OTTAWA AND
CENTRAL AND NORTHERN KENT COUNTIES BY BETWEEN 9 PM AND MIDNIGHT.
SINCE THE PRECIPITATION AREA ALREADY IS OVER CENTRAL WISCONSIN AND
IS HEADED EAST... IT WOULD SEEM MORE THAN REASONABLE THIS WOULD
IMPACT CENTRAL LOWER MICHIGAN THIS EVENING. THERE IS GOOD LIFT IN
THE DGZ AS THIS FEATURE MOVES THROUGH THE AREA SO THAT SHOULD HELP
THE SNOWFLAKE PRODUCTION. WITH SURFACE DEW POINTS IN THE MID 20S
THE SNOW WILL WET BULB DOWN THE AIR TEMP QUICKLY SO SNOW WILL REACH
THE GROUND.
ONCE THAT FEATURE MOVES EAST OF THE CWA LATER THIS EVENING SHORT
WAVE RIDGING FOLLOWS LATE TONIGHT INTO MIDDAY THURSDAY. THAT
SHOULD ALLOW THE SKIES TO BECOME PARTLY CLOUDY...AT LEAST FOR A
TIME.
THEN WE HAVE THE ISSUE OF OUR STORM ON THURSDAY NIGHT. THE GFS AND
NAM HAVE BEEN CONSISTENTLY FARTHER NORTH THEN THE ECMWF HAS BEEN
WITH THIS SYSTEM. HOWEVER... THE ECMWF HAS FINALLY SHOWED A
SIGNIFICANT SHIFT NORTHWARD IN THE TRACK OF THE SYSTEM THURSDAY
NIGHT. THE REGIONAL GEM IS FARTHER NORTH AND WEST THAN IS THE
HEMISPHERIC GEM... TRACKING THE LOW NEAR DETROIT LATE THURSDAY
NIGHT. THERE IS SIGNIFICANT FGEN SUPPORT OF THIS EVENT AS IT IS
EXIT REGION OF 165 KNOT 300 MB JET CORE THAT TURNS CYCLONIC AS
IT HEADS NORTHEAST TOWARD CENTRAL OHIO FRIDAY MORNING. THIS ALSO
CREATES QUIET THE TROWAL FEATURE WITH STRONG ISOTROPIC LIFT. THERE
IS 3 TO 4 G/KG OF WATER NEAR 700 MB WHILE THIS IS GOING ON SO
SNOWFALL AMOUNTS OF 3 TO 6 INCHES SHOULD BE EASY TO DO WITH THIS
SET UP.
I WOULD HAVE ISSUED A WINTER STORM WATCH FOR THIS EVENT EXPECT FOR
THE ISSUE OF MODEL UNCERTAINTY. I WILL LET THE MIDNIGHT SHIFT
CONSIDER DOING JUST THAT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 400 PM EST WED FEB 22 2012
UNSETTLED/ACTIVE WEATHER IS EXPECTED TO GENERALLY CONTINUE THROUGH
THE LONG TERM PORTION OF THE FORECAST...IF NOT THE NEXT COUPLE OF
WEEKS. MAIN ITEMS OF CONCERN ARE LINGERING SNOW ON FRI...LAKE EFFECT
FRI NIGHT/SAT...SYSTEM COMING IN LATE SUN THROUGH MON...AND LAKE
EFFECT AGAIN ON TUE.
AN ACTIVE JET STREAM IS EXPECTED TO AFFECT MOST OF THE COUNTRY
THROUGH THE NEXT WEEK. WE ARE EXPECTING TO SEE STRONG PIECES OF
ENERGY BE PUSHED ACROSS THE COUNTRY...FUELED BY A VERY STRONG JET
OVER THE NRN PACIFIC. A LOT OF THIS ENERGY IS EXPECTED TO DIVE SE
INTO THE WRN STATES...BEFORE LIFTING E/NE TOWARD THE GREAT LAKES
REGION.
WE WILL SEE THE FIRST IN THE SERIES OF PV ANOMALIES/WAVES BE MOVING
OUT OF THE AREA AFTER DEPOSITING ACCUMULATING SNOW THU NIGHT AND
INTO FRI. IN THE WAKE OF THIS PHASED UPPER FEATURE...A POOL OF
ARCTIC AIR TO OUR NW WILL BE TAPPED AND WILL PUSH INTO THE AREA.
SYNOPTIC SNOW WILL LIKELY BE ONGOING EARLY ON FRI BEFORE TAPERING
OFF DURING THE DAY. THE SNOW WILL TRANSITION TO SOME LAKE EFFECT AS
H850 TEMPS DROP DOWN TO AROUND -10C TO -12C. WE COULD SEE SOME
DECENT LAKE EFFECT ACCUMS FOR MAINLY NW FAVORED AREAS WITH MOISTURE
POTENTIALLY UP THROUGH 10K FT LATE FRI AND FRI NIGHT. INVERSION
HEIGHTS WILL GRADUALLY FALL THROUGH SAT AS THE UPPER FLOW WILL
TRANSITION TO ANTI-CYCLONIC BY SAT EVENING.
WE WILL SEE A BRIEF BREAK IN THE WEATHER THEN SAT NIGHT THROUGH A
GOOD PORTION OF SUN FOR MOST AREAS AS RIDGING BUILDS IN. NW AREAS
COULD SEE SOME LIGHT PCPN SUN AFTERNOON AS WAA/ISENTROPIC ASCENT
STRENGTHENS AHEAD OF THE NEXT SYSTEM. THE UNSETTLED WEATHER WILL
SPREAD ACROSS THE ENTIRE AREA SUN NIGHT AS THE NEXT STRONG WAVE
DIVING INTO THE SW U.S. EARLY IN THE WEEKEND WILL LIFT NE. THIS WILL
LIKELY TAP SOME WARMER AND MOIST AIR FROM THE GULF AND ADVECT IT
INTO THE AREA LATE SUN THROUGH MON MORNING. PCPN COULD START OFF AS
SNOW...BUT SHOULD CHANGE OVER TO RAIN FOR A PERIOD SUN NIGHT AND
EARLY MON. THUNDER CAN NOT EVEN BE RULED OUT WITH THE STRONG FORCING
ASSOCIATED WITH THE SYSTEM. NOT CONFIDENT ENOUGH YET TO ADD THUNDER
INTO THE FCST.
THE COLD FRONT WILL MOVE THROUGH ON MON...AND A FLOOD OF COLDER AIR
WILL MOVE IN ACROSS THE STATE. THIS WILL HELP TO START THE LAKE
EFFECT BACK UP AS H850 TEMPS DROP BACK DOWN TO AROUND -10C TO -12C.
MODELS ARE INDICATING THOUGH THAT THE LOW LEVEL FLOW WILL TEND TO BE
NE WITH THE WAY THE RIDGE BUILDS IN FROM THE NW. THIS WILL TEND TO
LIMIT THE LAKE EFFECT CHCS AND AMOUNTS. QUITE A BIT OF UNCERTAINTY
WITH REGARDS TO TIMING AND TRACK WITH ANOTHER WAVE THAT IS EXPECTED
TO LIFT OUT FROM THE WRN U.S. BY MID WEEK NEXT WEEK.
&&
.AVIATION...(FOR THE 21Z TAFS THROUGH 21Z THURSDAY AFTERNOON)
ISSUED AT 400 PM EST WED FEB 22 2012
I UPDATED THE TAFS TO ALLOW FOR THE BURST OF SNOW ASSOCIATED WITH
THE SHORTWAVE CROSSING EASTERN WISCONSIN AT 3 PM. THIS SHOULD REACH
THE MKG/GRR TAFS SITES AROUND 03Z AND BE EAST OF THERE BY 06Z. BY
THE TIME IT REACHES LAN AROUND 05Z IT SHOULD WEAKEN. I EXPECT IFR
CIGS/VSBY AS THE SNOW BAND MOVES ACROSS THE I-96 TAFS SITES.
THE I-94 TAF SITES SHOULD SEE MVFR CONDITIONS AS THIS ROLLS
THROUGH. ALL AREAS SHOULD SEE CLEARING TO VFR BY 09Z ONCE THIS
FEATURE HAS EXITED THE AREA.
&&
.MARINE...
ISSUED AT 400 PM EST WED FEB 22 2012
WINDS AND WAVES ARE STILL IN THE SMALL CRAFT ADVISORY RANGE LATE
THIS AFTERNOON. WINDS AND WAVES WILL DIMINISH TONIGHT OVERNIGHT AS
THE SURFACE RIDGE GETS CLOSER TO THE AREA. I WILL LET THE ADVISORY
EXPIRE AS SCHEDUALED.
&&
.HYDROLOGY...
ISSUED AT 400 PM EST WED FEB 22 2012
NO SIGNIFICANT HYDROLOGY ISSUES ARE EXPECTED AS THE PRECIPITATION
THAT FALLS WILL BE IN THE FROM FOR SNOW. NONE OF RIVERS ARE AT OR
ABOVE ACTION STAGE CURRENTLY.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM....NJJ
AVIATION...WDM
MARINE...WDM
HYDROLOGY...WDM
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
404 PM CST WED FEB 22 2012
.DISCUSSION...
SUMMARY...QUITE THE DAY HERE AT THE NWS OFFICE TODAY. THREE
POTENTIAL SNOW STORMS IN THE FORECAST AREA OVER THE NEXT 160 HOURS
AND PLENTY OF MODEL DISAGREEMENT TO GO ALONG WITH IT.
FIRST THINGS FIRST...SHORTWAVE PASSING THROUGH THIS AFTERNOON
YIELDING ISOLATED TO SCATTERED LIGHT SNOW SHOWERS...SHOULD BE
THROUGH EARLY THIS EVENING AND LOOKS DRY FOR SEVERAL HOURS BEFORE
THE SURFACE LOW FROM THE NORTHWEST. LOOK OF POTENTIAL WITH THIS
STORM FOR TONIGHT...BUT THE QUESTION TODAY HAS NOT BEEN IF THERE
WILL BE A 6+" SNOWBAND...BUT WHERE. IN GENERAL...THERE HAS BEEN
TWO CLUSTERS OF MODEL GUIDANCE: THE UKMET/EC IN ONE CAMP AND THE
GFS/GEM/SREF/ IN THE OTHER. THE 12Z NAM WAS AN OUTLIER TO THE
NORTH AND BROUGHT THE HEAVY SNOW ACROSS CENTRAL MN...INCLUDING THE
TWIN CITIES METRO. THE 18Z NAM JOINED THE GFS/SREF/GEM CAMP AND
CAME IN MUCH FURTHER SOUTH. DEBATED ON UPGRADING THE WATCH TO A
COMBINATION OF WARNING/ADVISORY WITH THE HEAVIEST ACCUMULATIONS IN
MARTIN AND FARIBAULT COUNTIES. IN FACT...EVEN HAD THE WARNING
DRAWN UP LATE THIS AFTERNOON...BUT THE LAST FRAME OF THE HRRR
AGREES QUITE WELL WITH THE ECMWF AND WOULD KEEP ALMOST ALL OF THE
SNOW OUT OF THE FORECAST AREA.
THERE IS ALREADY A LIGHTNING STRIKE UPSTREAM IN MONTANA THIS
AFTERNOON...WHICH IS USUALLY A PRETTY GOOD INDICATOR OF THE
STRENGTH OF THIS SYSTEM. NO SURPRISE WITH 992-993MB SURFACE LOW
DROPPING SOUTH ACROSS WESTERN IA BASED ON THE NAM/GFS...THERE IS
VERY GOOD 800-600MB FGEN TO GO ALONG WITH NEGATIVE EPV AND AT
LEAST SOME ELEVATED INSTABILITY-BEST LI APPROACHES THE FORECAST
AREA WITH 2/3 GRAM MIXING RATIOS OFF THE ISENTROPIC SURFACES. THE
FORECAST SIDES WITH THE GFS/GEM/NAM/SREF CLUSTER OF SOLUTIONS.
HOWEVER...LOW CONFIDENCE WITH NOW THE LATEST HRRR AGREEING QUITE
WELL WITH THE ECMWF. IT`S A FEAST OF FAMINE SITUATION-THERE WILL
LIKELY BE 6-10 INCHES...POSSIBLY A FOOT...IN A NARROW CORRIDOR
WHERE THE BEST FORCING SETS UP AND NOT MUCH TO THE NORTH OF IT.
DRAMATICALLY REDUCED POPS AND AMOUNT OF SNOW IN METRO...MIGHT BE
NOTHING AT. USUALLY GOOD SUBSIDENCE ON NORTH SIDE OF THE
DEFORMATION.
IN THE EXTENDED...THE SUNDAY/MONDAY SYSTEM LOOKS POTENT...JUST NOT
SOME MUCH FOR HERE WITH THE SURFACE LOW TRACKING OVERHEAD AND HIGH
POTENTIAL FOR DRY SLOT BASED ON THE ASSORTMENT OF OPERATIONAL RUNS
AND ENSEMBLE GUIDANCE. UNLESS SOMETHING CHANGES...A LOT OF SNOW
AND WIND IN THE DAKOTAS AND NORTHERN MN AND NOT MUCH HERE. GFS
SPITS OUT THE HIGHEST QPF...BUT IT MIGHT BE OVERDONE. THERE ARE
FAIRLY HIGH POPS IN THE FORECAST...BUT OVERALL...DOESN`T LOOK LIKE
ANYTHING MAJOR IN THE IMMEDIATE AREA. THERE`S ANOTHER WHOPPER OFF
THE GFS THIS TIME NEXT...BUT NOT SHOWING UP AS MUCH ON THE ECMWF
AND GFS ENSEMBLE TO SOME DEGREE. THE 12Z GFS HAD A BAND OF 12-18"
IN SOUTHERN MN...SOMETHING THAT WILL LIKELY CHANGE WITH TIME.
&&
.AVIATION.../18Z TAF ISSUANCE/
BIG ISSUE THIS TAF PERIOD IS POTENTIAL FOR A WINTER STORM LATE
TONIGHT/THURSDAY MORNING. FOR THESE TAFS...DISCARDED THE NAM /TOO
FAR NORTH/ AND BASICALLY TRENDED EVERYTHING AFTER THIS AFTERNOON
HEAVILY TOWARD THE GFS. FOR THIS AFTERNOON...WEAK UPPER WAVE
WORKING ACROSS MN WILL CONTINUE 050-100 TYPE CLOUD COVER.
EXPECTING NOTHING MORE OUT OF THESE CLOUDS THAN A BRIEF SN SHOWER
WITH MVFR CONDITIONS...BUT NOT ENOUGH TO WARRANT A TEMPO GROUP
ANYWHERE. GREATEST POTENTIAL FOR -SN TODAY WOULD BE AT STC/AXN.
FOR TONIGHT...WILL BE WATCHING WHAT IS LOOKING TO BE A BAND OF
HEAVY SNOW DEVELOPING ACROSS THE DAKOTAS THAT WILL MOVE INTO
SW/SRN MN...MAINLY SOUTH OF MPX TERMINALS. THE TERMINAL THAT LOOKS
TO BE MOST AT RISK FOR SEVERAL INCHES OF SNOW WOULD BE RWF. WHERE
SNOW DOES COME...MODELS INDICATING A SLOWER PROGRESSION WITH THIS
SYSTEM...SO DELAYED PRECIP MENTION A FEW HOURS FROM PREVIOUS TAF.
BIGGEST UNCERTAINTY IS HOW FAR NORTH DOES THE SNOW GET...GOING
WITH THE PREFERRED GFS/SREF/GEM BLEND...MSP AND EAU MAY NOT SEE
MUCH OF ANYTHING AT ALL. CIGS/VSBYS A TOUGH CALL AS WELL. IN THE
SNOW...IFR OR LOWER CONDITIONS ARE ALMOST CERTAIN...BUT NORTH OF
THE SNOW...THE GFS WOULD INDICATE IT MAY BE TOUGH TO EVEN GET
MVFR CIGS...WITH CLOUDS AT STC/MSP/RNH/EAU HANGING OUT AOA 10K FT.
KMSP...WEIGHED TAF HEAVILY TOWARD THE GFS...BUT DID NOT COMPLETELY
ABANDON THE SNOW IDEA AS THE GFS HAS. CONFIDENCE PRETTY HIGH THAT
A HEAVY BAND OF SNOW IS HEADING FOR SRN MN...BUT CONFIDENCE IS
PRETTY LOW ON JUST HOW FAR NORTH THE SNOW SHIELD MAKES. IF MSP
DOES SEE SNOW...IT WOULD LIKELY ONLY TOP OUT AROUND AN INCH GIVEN
CURRENT THINKING. CONFIDENCE IN CIG FORECAST TOMORROW LOW AS
WELL...BUT WOULD NOT BE SURPRISED IF AT LEAST MVFR CIGS SNEAK
NORTH OUT OF THE SNOW. FOR WINDS...SFC RIDGE WILL MOVE THROUGH
INTO TONIGHT...WITH WINDS MAINLY LGT AND VRB UNTIL AFTER
MIDNIGHT...WHEN THEY BECOME ESTABLISHED OUT OF THE EAST. OF COURSE
IF THE NAM SOLUTION IS CORRECT...THERE WOULD BE SIGNIFICANT WEATHER
ISSUES FOR THE MORNING RUSH TOMORROW.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER STORM WARNING FROM 3 AM TO 6 PM CST THURSDAY FOR
FARIBAULT-FREEBORN-MARTIN-WATONWAN.
WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM CST THURSDAY FOR BLUE
EARTH-BROWN-REDWOOD-STEELE-WASECA.
WI...NONE.
&&
$$
CLF/MPG
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1136 AM PST Wed Feb 22 2012
.SYNOPSIS...
A strong cold front will move through the Pacific Northwest this
morning. Strong winds will develop behind the cold front, and gusty
winds will persist through early this evening. Winds will subside
tonight. The weather on Thursday will be quiet. The threat for snow
will return Friday night into Saturday with the arrival of a cool
low pressure system.
&&
.DISCUSSION...
rest of today...Surface cold front now nearly through the entire
forecast area as attested to by strong pressure rises over all of
eastern Washington and north Idaho. The air mass behind the cold
front has destabilized nicely as cooling aloft outpaces the
cooling or slight warming near the ground. RUC CAPE values have
climbed to anywhere from 100-300 j/KG over the NE corner of
Washington into the Lake Pend Oreille area...which has resulted a
growing shower trend over that area. The best instability is
expected to slide into the central Panhandle later this afternoon
and that`s where we expect to see the most numerous showers by late
this afternoon. The predominate precipitation type will be a mix
of rain and snow in the heavier showers over the valleys...with
snow over the mountains. Based on above freezing surface
temperatures and even warmer roads...valley accumulations will not
be an issue.
The other story for today will be the wind. All Mesoscale models
have transitioned the Inland NW to a cold air advection regime at
850 mb with strong downward momentum expected through the
remainder of the afternoon. The strongest 850 mb winds...ranging
from 40-50kts...will generally impact locations south of a line
from the Waterville Plateau to the southern half of the Palouse.
Current wind highlights cover the situation quite well as the
strongest winds will occur over the Palouse...Blue Mountains...and
Lewiston area. Not sure if the strongest winds under this jet will
mix down into the Columbia Basin...but if so we could see wind
gusts to 50 MPH...which is just below high wind warning criteria.
The winds at 850 mbs...and thus at the ground should peak by early
afternoon. Farther north...there is the possibility that some of
the showers could mix some higher winds down to the ground...but
that should be rather spotty. FX
&&
.AVIATION...
18Z TAFs: VFR conditions are expected at all sites through the
forecast period. The main story will be the wind. Strongest speeds
will likely impact KPUW and KLWS with gusts approaching 50
MPH...but shear will not be an issue due to deep mixing through
the boundary layer. Winds will begin to taper off during the
evening. FX
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 48 28 40 24 40 28 / 10 10 10 10 30 70
Coeur d`Alene 48 28 40 23 40 28 / 30 10 10 10 40 70
Pullman 52 29 40 26 41 31 / 40 10 10 0 10 70
Lewiston 59 34 48 30 48 34 / 20 10 10 0 10 50
Colville 47 25 44 21 42 25 / 40 10 0 10 60 70
Sandpoint 48 27 39 22 37 25 / 70 20 10 10 50 80
Kellogg 45 28 39 23 40 26 / 100 40 40 10 30 80
Moses Lake 58 29 47 25 45 28 / 10 0 0 0 20 60
Wenatchee 52 30 45 27 42 28 / 10 10 0 10 30 60
Omak 54 23 40 19 41 22 / 10 0 0 10 60 60
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Wind Advisory until 10 PM PST this evening for Coeur d`Alene
Area-Northern Panhandle.
High Wind Warning until 4 PM PST this afternoon for Idaho
Palouse-Lewiston Area.
Wind Advisory until 7 PM PST this evening for Lewis and Southern
Nez Perce Counties.
WA...Wind Advisory until 10 PM PST this evening for Spokane Area-
Upper Columbia Basin.
High Wind Warning until 4 PM PST this afternoon for Lower
Garfield and Asotin Counties-Washington Palouse.
Wind Advisory until 7 PM PST this evening for Moses Lake Area-
Waterville Plateau-Wenatchee Area.
&&
$$