Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 02/28/13
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1022 AM MST TUE FEB 26 2013
.UPDATE...
ISSUED AT 1021 AM MST TUE FEB 26 2013
SPOTTER REPORTS FROM THE GRAND MESA HAVE NOW REACHED A FOOT IN A
FEW SPOTS WITH SEVERAL SNOTELS APPROACHING 8 TO 10 INCHES AND
HEAVY SNOW CONTINUES TO FALL. LIGHT NORTHERLY COMPONENT TO LOW
LEVEL WIND FIELDS HELPING TO FUEL THIS REGION WITH PLENTY OF
MOISTURE. WITH TEMPS RIGHT IN THE DENDRITIC GROWTH ZONE...VERY
EFFICIENT SNOW PRODUCTION WILL CONTINUE FOR AT LEAST A FEW HOURS.
HAVE UPGRADED THE WINTER WEATHER ADVISORY TO A WINTER STORM
WARNING AND BOOSTED AMOUNTS EVEN HIGHER...WITH LOCAL ACCUMULATIONS UP
TO 20 INCHES NOT OUT OF THE QUESTION.
SNOW HAS TAPERED OFF IN THE MONTROSE AREA...BUT SCATTERED SHOWERS
WILL BE REDEVELOPING AND MOVING THROUGH LATER TODAY AND THIS
EVENING. JUST TO THE EAST OF MONTROSE ALONG HIGHWAY 50...SNOW
CONTINUES TO FALL OVER THE CERRO SUMMIT AREA AND EAST INTO
GUNNISON. SO TRAVEL WILL REMAIN HAZARDOUS AND HIGHLIGHTS WILL
REMAIN IN EFFECT.
AND FINALLY...SNOW CONTINUES TO FALL ALONG THE INTERSTATE 70
CORRIDOR AND SEVERAL ACCIDENTS...INCLUDING ROLLOVERS HAVE BEEN
REPORTED. IMPACT ON THIS HIGHLY TRAVELLED CORRIDOR REMAINS HIGH
AND WILL CONTINUE THE HIGHLIGHTS THROUGH THIS AFTERNOON.
UPDATE ISSUED AT 813 AM MST TUE FEB 26 2013
IMPACT BASED ADVISORIES HAVE BEEN ISSUED FOR SEVERAL OF THE LOWER
VALLEYS THIS MORNING AS LIGHT SNOW CONTINUES TO HAMPER THE MORNING
COMMUTE. SNOW WILL BECOME MORE SCATTERED IN NATURE THIS THIS
AFTERNOON...BUT CONVECTIVE ELEMENT WILL ENHANCE
SHOWERS...RESULTING IN LOCALIZED HEAVY SNOWFALL. SO HAVE CARRIED
THE VALLEY HIGHLIGHTS THROUGH LATE THIS AFTERNOON AND EVENING
BASED ON LOCATION. IN ADDITION...AREA OF CONVERGENCE SETTING UP
ACROSS THE SAN JUANS AND LIGHT SNOW CONTINUES TO DRAG SOUTH INTO
THE NORTHWEST SAN JUANS. BANDING PRECIP ALONG THE UNCOMPAHGRE
PLATEAU SHIFTS SLOWLY SOUTH AND WILL PROVIDE ADDITIONAL SNOWFALL
THROUGH LATE THIS MORNING. LIGHT NORTHERLY COMPONENT TO BOUNDARY
LAYER WINDS WILL KEEP DRIVING MOISTURE INTO THE GORGE SOUTH OF
OURAY...RESULTING IN LOCALLY HEAVY SNOWFALL. AMOUNTS MAY EXCEED 6
INCHES IN THIS AREA AND LOW END ADVISORY APPEARS JUSTIFIED. PRECIP
WINDS DOWN LATER THIS AFTERNOON AND OVERNIGHT FROM SOUTHWEST TO
NORTHWEST AS THE MAIN UPPER LEVEL LOW LIFTS OUT INTO THE PLAINS.
ZONES HAVE BEEN UPDATED WITH NEW SNOW TOTALS AND POPS.
UPDATE ISSUED AT 621 AM MST TUE FEB 26 2013
GRID UPDATE TO BOOST POPS WITH WIDESPREAD SNOW OCCURRING BENEATH
THE ENHANCED CLOUD OVER NW AND WEST CENTRAL COLORADO. TROUGH AXIS
IS OVER ERN UTAH AT 13Z...BUT UPPER CIRCULATION IS PROGGED BY THE
13KM RAP MODEL TO BE CENTERED OVER THE NWRN SAN JUAN MOUNTAINS BY
EARLY AFTERNOON. THIS AREA WILL NEED TO BE MONITORED AS NORTHWEST
FLOW AND NEGATIVE EQUIVALENT POTENTIAL VORTICITY SUGGEST BANDS OF
SNOW MAY BE TRAINING INTO THE GORGE. CURRENTLY ON THE RADAR...ONE
BAND OF SNOW IS TRYING TO BECOME ESTABLISHED ALONG THE UNCOMPAHGRE
PLATEAU. A WINTER WEATHER ADVISORY MAY BE NEEDED FOR ZONE 18.
REMAINDER OF THE FORECAST AREA APPEARS ON TRACK WITH SNOW BEGINNING
TO SPREAD OVER THE ELK MOUNTAINS TOWARD THE GORE RANGE.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 355 AM MST TUE FEB 26 2013
THE NEXT WEATHER MAKER IN THE FORM OF AN OPEN TROUGH HAS BEGUN TO
MOVE INTO THE AREA EARLY THIS MORNING. CLOUDS HAVE INCREASED AND
LOWERED AHEAD OF THIS WAVE...WITH RADAR ECHOES REFLECTING THIS
TREND. ALSO SINCE AROUND 1 AM MST...K3MW IN THE PARK RANGE HAS
REPORTED SNOW...AND EXPECT SHOWERS HAVE DEVELOPED AT OTHER
NORTHERN MOUNTAIN LOCATIONS AS WELL.
THE LOW CENTER WILL DROP FROM THE NORTHERN ROCKIES SOUTH-SOUTHEAST
ACROSS WY BY MID-MORNING...AND OVER NORTHWEST CO BY MIDDAY. ALSO A
NOT VERY DISTINCT SURFACE FRONT AHEAD OF THE UPPER LEVEL TROUGH
WILL SEEP OVER THE AREA FROM NORTHWEST TO SOUTHEAST EARLY TODAY.
AS A RESULT SNOW WILL CONTINUE TO SPREAD IN FROM THE NORTHWEST
THROUGH THE NEXT 3-12 HOURS. BY DAYLIGHT...SNOW SHOULD BE
WIDESPREAD ACROSS THE NORTHERN MOUNTAINS AND WILL FILL INTO THE
WEST-CENTRAL CO MOUNTAINS BY MID MORNING. SNOW WILL CONTINUE
THROUGH THE AFTERNOON AS THE -32/-33 COLD POOL AT 500 MB MOVES
OVER THE AREA. THE PRESENT FORECAST LOOKS ON TRACK WITH LOW-END
ADVISORY AMOUNTS IN THE NORTHERN AND WEST-CENTRAL MOUNTAINS...
FAVORING THE NORTHWEST FACING SLOPES. OTHER MOUNTAIN AREAS SHOULD
SEE A PERIOD OF SNOW...BUT WITH LIGHTER ACCUMULATIONS. VALLEYS
WILL SEE ISOLATED TO SCATTERED SNOW SHOWERS...WITH BETTER COVERAGE
OVER MUCH OF THE NORTH...AND LITTLE TO NO SHOWERS ALONG OUR WEST
AND SOUTHWEST BORDERS. BY LATE AFTERNOON ACTIVITY WILL BEGIN TO
DIMINISH IN THE WESTERN VALLEYS AS DRIER AIR MOVES IN. HOWEVER
SNOW WILL CONTINUE IN THE CO MOUNTAINS THROUGH THE EVENING THE AS
THE COLD AIR ALOFT REMAINS IN PLACE...AND THE FAVORED DENDRITIC
GROWTH LAYER WILL REMAIN SATURATED AND NEAR MOUNTAIN TOP LEVEL.
THEN BY LATE TONIGHT THE NORTH FLOW WILL CONTINUE TO PRODUCE LIGHT
SNOW ALONG THE NORTH SLOPES OF THOSE FAVORED NORTH AND CENTRAL
MOUNTAINS. THIS ACTIVITY WILL GRADUALLY DIMINISH TOWARDS SUNRISE
WED.
ONE AREA THAT SHOULD BE WATCHED IS THE UNCOMPAHGRE GORGE AT AND
NEAR OURAY CO. THIS AREA COULD PICK UP SOME DECENT ACCUMULATIONS
AS THE FLOW TURNS AROUND TO NORTH LATER TODAY THROUGH THIS
EVENING. HOWEVER...I CHOSE NOT TO INCLUDE CO ZONE 18 IN THE
ADVISORY AS THE DURATION WILL BE SHORT...AND THE HEAVIER
ACCUMULATIONS ARE EXPECTED TO BE LOCALIZED.
ANY REMAINING SHOWERS IN THE NORTHERN MOUNTAINS WILL QUICKLY WIND
DOWN THROUGH THE MORNING ON WED...WITH ONLY A FEW LINGERING BEYOND
MIDDAY NEAR THE CONTINENTAL DIVIDE.
BELOW NORMAL TEMPERATURES WILL CONTINUE.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 355 AM MST TUE FEB 26 2013
RIDGE AMPLIFIES OVER THE WEST COAST STATES WEDNESDAY NIGHT INTO
THURSDAY NIGHT...BUT THE GFS AND TO A LESSER EXTENT THE SREF
INDICATE A DISTURBANCE WILL STREAM OVER THE NRN DIVIDE MOUNTAINS FOR
A CHANCE OF SNOW. THE ECMWF APPEARS TO BE TRENDING THIS DIRECTION
SO THE CHANCE POPS APPEAR WARRANTED. THIS WOULD BE A FAST MOVING
DISTURBANCE AND ANY SNOWFALL WILL BE LIGHT.
IN THE BIGGER PICTURE...A WARMING TREND WILL OCCUR THIS UPCOMING
WEEKEND AS A WARM RIDGE MOVES EAST ACROSS THE INTERMOUNTAIN WEST AND
ROCKY MOUNTAIN STATES ON SATURDAY AND SUNDAY. EXPECT WARMING TEMPS
AT ALL LOCATIONS...OR SLIGHTLY ABOVE AVERAGE COMPARED TO CLIMO.
RECENT TEMPS HAVE BEEN BELOW NORMAL...SO THIS WARMING WILL FEEL MORE
SIGNIFICANT THAN COMPARED TO CLIMO.
FORECAST CONFIDENCE DIMINISHES SUNDAY NIGHT AND MONDAY AS A
SIGNIFICANT SHORT WAVE PUNCHES ACROSS THE PACIFIC NORTHWEST AND NRN
INTERMOUNTAIN REGION. SOME ENTRAINMENT OF SUBTROPICAL MOISTURE IS
POSSIBLE AHEAD OF THIS FEATURE...AND THIS COULD LEAD TO CHANCE OF
PRECIPITATION SUNDAY NIGHT. MONDAY BECOMES MORE MURKY AS THE ECMWF
SHOWS MUCH COLDER AIR SPILLING INTO THE FORECAST AREA. WOULD LIKE
TO SEE SOME CONFIRMATION BY THE GFS OR RUN TO RUN CONTINUITY BY THE
EURO MODEL. WILL NOT MAKE TOO MANY CHANGES FROM THE CONSENSUS
OUTPUT...BUT DID LOWER MAX TEMPS ACROSS THE NWRN COLORADO VALLEYS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1021 AM MST TUE FEB 26 2013
THE UPPER LEVEL TROF CROSSING EASTERN UTAH AND WESTERN COLORADO
WILL CONTINUE TO BRING WIDESPREAD SNOWFALL TO AIRPORTS EAST OF A
2OW KCAG-KMTJ-PSO LINE DURING THE AFTERNOON AND EARLY
EVENING...WITH SCATTERED TO ISOLATED SHOWERS WEST OF THIS LINE.
MVFR TO IFR CONDITIONS CAN BE EXPECTED OVER THE KEGE AND KASE
TERMINALS THROUGH THE EVENING PERIOD AS WELL. KRIL...KGJT AND KMTJ
ARE RUNNING A VFR LEVELS BUT PASSING SHOWERS THIS AFTERNOON COULD
BRING TEMPORARY LOWERED FLIGHT CRITERIA THROUGH THIS TIME AS WELL.
MOUNTAIN OSBCURATIONS ARE ALSO LIKELY TO PERSIST THROUGH THE LATE
EVENING AND EARLY MORNING HOURS AS THIS WAVE SLOWLY MOVES ONTO THE
PLAINS AND BRINGS IN SOME DRIER AIR.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL 9 PM MST THIS EVENING FOR COZ012-
017-018.
WINTER STORM WARNING UNTIL 9 AM MST WEDNESDAY FOR COZ009.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST TONIGHT FOR COZ007-
008.
WINTER WEATHER ADVISORY UNTIL 9 AM MST WEDNESDAY FOR COZ004-010-
013.
WINTER WEATHER ADVISORY UNTIL 6 PM MST THIS EVENING FOR COZ011-
014.
UT...NONE.
&&
$$
UPDATE...JDC
SHORT TERM...EH
LONG TERM...PF
AVIATION...15
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
813 AM MST TUE FEB 26 2013
.UPDATE...
ISSUED AT 813 AM MST TUE FEB 26 2013
IMPACT BASED ADVISORIES HAVE BEEN ISSUED FOR SEVERAL OF THE LOWER
VALLEYS THIS MORNING AS LIGHT SNOW CONTINUES TO HAMPER THE MORNING
COMMUTE. SNOW WILL BECOME MORE SCATTERED IN NATURE THIS THIS
AFTERNOON...BUT CONVECTIVE ELEMENT WILL ENHANCE
SHOWERS...RESULTING IN LOCALIZED HEAVY SNOWFALL. SO HAVE CARRIED
THE VALLEY HIGHLIGHTS THROUGH LATE THIS AFTERNOON AND EVENING
BASED ON LOCATION. IN ADDITION...AREA OF CONVERGENCE SETTING UP
ACROSS THE SAN JUANS AND LIGHT SNOW CONTINUES TO DRAG SOUTH INTO
THE NORTHWEST SAN JUANS. BANDING PRECIP ALONG THE UNCOMPAHGRE
PLATEAU SHIFTS SLOWLY SOUTH AND WILL PROVIDE ADDITIONAL SNOWFALL
THROUGH LATE THIS MORNING. LIGHT NORTHERLY COMPONENT TO BOUNDARY
LAYER WINDS WILL KEEP DRIVING MOISTURE INTO THE GORGE SOUTH OF
OURAY...RESULTING IN LOCALLY HEAVY SNOWFALL. AMOUNTS MAY EXCEED 6
INCHES IN THIS AREA AND LOW END ADVISORY APPEARS JUSTIFIED. PRECIP
WINDS DOWN LATER THIS AFTERNOON AND OVERNIGHT FROM SOUTHWEST TO
NORTHWEST AS THE MAIN UPPER LEVEL LOW LIFTS OUT INTO THE PLAINS.
ZONES HAVE BEEN UPDATED WITH NEW SNOW TOTALS AND POPS.
UPDATE ISSUED AT 621 AM MST TUE FEB 26 2013
GRID UPDATE TO BOOST POPS WITH WIDESPREAD SNOW OCCURRING BENEATH
THE ENHANCED CLOUD OVER NW AND WEST CENTRAL COLORADO. TROUGH AXIS
IS OVER ERN UTAH AT 13Z...BUT UPPER CIRCULATION IS PROGGED BY THE
13KM RAP MODEL TO BE CENTERED OVER THE NWRN SAN JUAN MOUNTAINS BY
EARLY AFTERNOON. THIS AREA WILL NEED TO BE MONITORED AS NORTHWEST
FLOW AND NEGATIVE EQUIVALENT POTENTIAL VORTICITY SUGGEST BANDS OF
SNOW MAY BE TRAINING INTO THE GORGE. CURRENTLY ON THE RADAR...ONE
BAND OF SNOW IS TRYING TO BECOME ESTABLISHED ALONG THE UNCOMPAHGRE
PLATEAU. A WINTER WEATHER ADVISORY MAY BE NEEDED FOR ZONE 18.
REMAINDER OF THE FORECAST AREA APPEARS ON TRACK WITH SNOW BEGINNING
TO SPREAD OVER THE ELK MOUNTAINS TOWARD THE GORE RANGE.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 355 AM MST TUE FEB 26 2013
THE NEXT WEATHER MAKER IN THE FORM OF AN OPEN TROUGH HAS BEGUN TO
MOVE INTO THE AREA EARLY THIS MORNING. CLOUDS HAVE INCREASED AND
LOWERED AHEAD OF THIS WAVE...WITH RADAR ECHOES REFLECTING THIS
TREND. ALSO SINCE AROUND 1 AM MST...K3MW IN THE PARK RANGE HAS
REPORTED SNOW...AND EXPECT SHOWERS HAVE DEVELOPED AT OTHER
NORTHERN MOUNTAIN LOCATIONS AS WELL.
THE LOW CENTER WILL DROP FROM THE NORTHERN ROCKIES SOUTH-SOUTHEAST
ACROSS WY BY MID-MORNING...AND OVER NORTHWEST CO BY MIDDAY. ALSO A
NOT VERY DISTINCT SURFACE FRONT AHEAD OF THE UPPER LEVEL TROUGH
WILL SEEP OVER THE AREA FROM NORTHWEST TO SOUTHEAST EARLY TODAY.
AS A RESULT SNOW WILL CONTINUE TO SPREAD IN FROM THE NORTHWEST
THROUGH THE NEXT 3-12 HOURS. BY DAYLIGHT...SNOW SHOULD BE
WIDESPREAD ACROSS THE NORTHERN MOUNTAINS AND WILL FILL INTO THE
WEST-CENTRAL CO MOUNTAINS BY MID MORNING. SNOW WILL CONTINUE
THROUGH THE AFTERNOON AS THE -32/-33 COLD POOL AT 500 MB MOVES
OVER THE AREA. THE PRESENT FORECAST LOOKS ON TRACK WITH LOW-END
ADVISORY AMOUNTS IN THE NORTHERN AND WEST-CENTRAL MOUNTAINS...
FAVORING THE NORTHWEST FACING SLOPES. OTHER MOUNTAIN AREAS SHOULD
SEE A PERIOD OF SNOW...BUT WITH LIGHTER ACCUMULATIONS. VALLEYS
WILL SEE ISOLATED TO SCATTERED SNOW SHOWERS...WITH BETTER COVERAGE
OVER MUCH OF THE NORTH...AND LITTLE TO NO SHOWERS ALONG OUR WEST
AND SOUTHWEST BORDERS. BY LATE AFTERNOON ACTIVITY WILL BEGIN TO
DIMINISH IN THE WESTERN VALLEYS AS DRIER AIR MOVES IN. HOWEVER
SNOW WILL CONTINUE IN THE CO MOUNTAINS THROUGH THE EVENING THE AS
THE COLD AIR ALOFT REMAINS IN PLACE...AND THE FAVORED DENDRITIC
GROWTH LAYER WILL REMAIN SATURATED AND NEAR MOUNTAIN TOP LEVEL.
THEN BY LATE TONIGHT THE NORTH FLOW WILL CONTINUE TO PRODUCE LIGHT
SNOW ALONG THE NORTH SLOPES OF THOSE FAVORED NORTH AND CENTRAL
MOUNTAINS. THIS ACTIVITY WILL GRADUALLY DIMINISH TOWARDS SUNRISE
WED.
ONE AREA THAT SHOULD BE WATCHED IS THE UNCOMPAHGRE GORGE AT AND
NEAR OURAY CO. THIS AREA COULD PICK UP SOME DECENT ACCUMULATIONS
AS THE FLOW TURNS AROUND TO NORTH LATER TODAY THROUGH THIS
EVENING. HOWEVER...I CHOSE NOT TO INCLUDE CO ZONE 18 IN THE
ADVISORY AS THE DURATION WILL BE SHORT...AND THE HEAVIER
ACCUMULATIONS ARE EXPECTED TO BE LOCALIZED.
ANY REMAINING SHOWERS IN THE NORTHERN MOUNTAINS WILL QUICKLY WIND
DOWN THROUGH THE MORNING ON WED...WITH ONLY A FEW LINGERING BEYOND
MIDDAY NEAR THE CONTINENTAL DIVIDE.
BELOW NORMAL TEMPERATURES WILL CONTINUE.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 355 AM MST TUE FEB 26 2013
RIDGE AMPLIFIES OVER THE WEST COAST STATES WEDNESDAY NIGHT INTO
THURSDAY NIGHT...BUT THE GFS AND TO A LESSER EXTENT THE SREF
INDICATE A DISTURBANCE WILL STREAM OVER THE NRN DIVIDE MOUNTAINS FOR
A CHANCE OF SNOW. THE ECMWF APPEARS TO BE TRENDING THIS DIRECTION
SO THE CHANCE POPS APPEAR WARRANTED. THIS WOULD BE A FAST MOVING
DISTURBANCE AND ANY SNOWFALL WILL BE LIGHT.
IN THE BIGGER PICTURE...A WARMING TREND WILL OCCUR THIS UPCOMING
WEEKEND AS A WARM RIDGE MOVES EAST ACROSS THE INTERMOUNTAIN WEST AND
ROCKY MOUNTAIN STATES ON SATURDAY AND SUNDAY. EXPECT WARMING TEMPS
AT ALL LOCATIONS...OR SLIGHTLY ABOVE AVERAGE COMPARED TO CLIMO.
RECENT TEMPS HAVE BEEN BELOW NORMAL...SO THIS WARMING WILL FEEL MORE
SIGNIFICANT THAN COMPARED TO CLIMO.
FORECAST CONFIDENCE DIMINISHES SUNDAY NIGHT AND MONDAY AS A
SIGNIFICANT SHORT WAVE PUNCHES ACROSS THE PACIFIC NORTHWEST AND NRN
INTERMOUNTAIN REGION. SOME ENTRAINMENT OF SUBTROPICAL MOISTURE IS
POSSIBLE AHEAD OF THIS FEATURE...AND THIS COULD LEAD TO CHANCE OF
PRECIPITATION SUNDAY NIGHT. MONDAY BECOMES MORE MURKY AS THE ECMWF
SHOWS MUCH COLDER AIR SPILLING INTO THE FORECAST AREA. WOULD LIKE
TO SEE SOME CONFIRMATION BY THE GFS OR RUN TO RUN CONTINUITY BY THE
EURO MODEL. WILL NOT MAKE TOO MANY CHANGES FROM THE CONSENSUS
OUTPUT...BUT DID LOWER MAX TEMPS ACROSS THE NWRN COLORADO VALLEYS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 355 AM MST TUE FEB 26 2013
SNOW OVER THE NORTHERN AND CENTRAL MOUNTAINS EARLY THIS MORNING
WILL SPREAD INTO THE SOUTHERN MOUNTAINS BY AROUND 14Z...AND THEN
QUICKLY BECOME WIDESPREAD.
AN UPPER LEVEL TROUGH WILL PASS OVER THE AREA FROM 12Z/TUE TO
00Z/WED. AS A RESULT...AIRFIELDS WILL LIKELY SEE PERIODS OF MVFR
CIGS AND VSBY WITH BRIEF IFR CONDITIONS POSSIBLE IN HEAVIER
SHOWERS. PERSISTENT MOIST NORTHWESTERLY FLOW WILL FAVOR PROLONGED
PERIODS OF SNOW AT AIRPORTS EAST OF A 2OW KCAG-KMTJ LINE DURING
THE AFTERNOON. IN CONTRAST...NORTHWEST WINDS ARE UNFAVORABLE FOR
THE SOUTHERN AIRPORTS...SPECIFICALLY KCEZ...KDRO AND KPSO WHICH
WILL EXPERIENCE DRY DOWNSLOPE FLOW THROUGHOUT THE DAY. THE
MOUNTAINS WILL BE OBSCURED THROUGH 06Z WITH GUSTY NORTHWEST WINDS
AT TIMES RESULTING IN MECHANICAL TURBULENCE IN THE LEE OF PEAKS
AND RIDGES. MOUNTAIN SNOW WILL DIMINISH AFTER 06Z...BUT SNOW
SHOWERS WILL CONTINUE ALONG NORTHWEST-NORTH FACING SLOPES OF THE
NORTH AND WEST-CENTRAL COLORADO MOUNTAINS. THEREFORE MOUNTAIN
OBSCURATIONS WILL CONTINUE ALONG THESE SLOPES.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL 9 PM MST THIS EVENING FOR COZ012-
017-018.
WINTER WEATHER ADVISORY UNTIL 9 AM MST WEDNESDAY FOR COZ004-009-
010-013.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST TONIGHT FOR COZ007-
008.
WINTER WEATHER ADVISORY UNTIL 6 PM MST THIS EVENING FOR COZ011-
014.
UT...NONE.
&&
$$
UPDATE...JDC
SHORT TERM...EH
LONG TERM...PF
AVIATION...EH
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
621 AM MST TUE FEB 26 2013
.UPDATE...
ISSUED AT 621 AM MST TUE FEB 26 2013
GRID UPDATE TO BOOST POPS WITH WIDESPREAD SNOW OCCURRING BENEATH
THE ENHANCED CLOUD OVER NW AND WEST CENTRAL COLORADO. TROUGH AXIS
IS OVER ERN UTAH AT 13Z...BUT UPPER CIRCULATION IS PROGGED BY THE
13KM RAP MODEL TO BE CENTERED OVER THE NWRN SAN JUAN MOUNTAINS BY
EARLY AFTERNOON. THIS AREA WILL NEED TO BE MONITORED AS NORTHWEST
FLOW AND NEGATIVE EQUIVALENT POTENTIAL VORTICITY SUGGEST BANDS OF
SNOW MAY BE TRAINING INTO THE GORGE. CURRENTLY ON THE RADAR...ONE
BAND OF SNOW IS TRYING TO BECOME ESTABLISHED ALONG THE UNCOMPAHGRE
PLATEAU. A WINTER WEATHER ADVISORY MAY BE NEEDED FOR ZONE 18.
REMAINDER OF THE FORECAST AREA APPEARS ON TRACK WITH SNOW BEGINNING
TO SPREAD OVER THE ELK MOUNTAINS TOWARD THE GORE RANGE.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 355 AM MST TUE FEB 26 2013
THE NEXT WEATHER MAKER IN THE FORM OF AN OPEN TROUGH HAS BEGUN TO
MOVE INTO THE AREA EARLY THIS MORNING. CLOUDS HAVE INCREASED AND
LOWERED AHEAD OF THIS WAVE...WITH RADAR ECHOES REFLECTING THIS
TREND. ALSO SINCE AROUND 1 AM MST...K3MW IN THE PARK RANGE HAS
REPORTED SNOW...AND EXPECT SHOWERS HAVE DEVELOPED AT OTHER
NORTHERN MOUNTAIN LOCATIONS AS WELL.
THE LOW CENTER WILL DROP FROM THE NORTHERN ROCKIES SOUTH-SOUTHEAST
ACROSS WY BY MID-MORNING...AND OVER NORTHWEST CO BY MIDDAY. ALSO A
NOT VERY DISTINCT SURFACE FRONT AHEAD OF THE UPPER LEVEL TROUGH
WILL SEEP OVER THE AREA FROM NORTHWEST TO SOUTHEAST EARLY TODAY.
AS A RESULT SNOW WILL CONTINUE TO SPREAD IN FROM THE NORTHWEST
THROUGH THE NEXT 3-12 HOURS. BY DAYLIGHT...SNOW SHOULD BE
WIDESPREAD ACROSS THE NORTHERN MOUNTAINS AND WILL FILL INTO THE
WEST-CENTRAL CO MOUNTAINS BY MID MORNING. SNOW WILL CONTINUE
THROUGH THE AFTERNOON AS THE -32/-33 COLD POOL AT 500 MB MOVES
OVER THE AREA. THE PRESENT FORECAST LOOKS ON TRACK WITH LOW-END
ADVISORY AMOUNTS IN THE NORTHERN AND WEST-CENTRAL MOUNTAINS...
FAVORING THE NORTHWEST FACING SLOPES. OTHER MOUNTAIN AREAS SHOULD
SEE A PERIOD OF SNOW...BUT WITH LIGHTER ACCUMULATIONS. VALLEYS
WILL SEE ISOLATED TO SCATTERED SNOW SHOWERS...WITH BETTER COVERAGE
OVER MUCH OF THE NORTH...AND LITTLE TO NO SHOWERS ALONG OUR WEST
AND SOUTHWEST BORDERS. BY LATE AFTERNOON ACTIVITY WILL BEGIN TO
DIMINISH IN THE WESTERN VALLEYS AS DRIER AIR MOVES IN. HOWEVER
SNOW WILL CONTINUE IN THE CO MOUNTAINS THROUGH THE EVENING THE AS
THE COLD AIR ALOFT REMAINS IN PLACE...AND THE FAVORED DENDRITIC
GROWTH LAYER WILL REMAIN SATURATED AND NEAR MOUNTAIN TOP LEVEL.
THEN BY LATE TONIGHT THE NORTH FLOW WILL CONTINUE TO PRODUCE LIGHT
SNOW ALONG THE NORTH SLOPES OF THOSE FAVORED NORTH AND CENTRAL
MOUNTAINS. THIS ACTIVITY WILL GRADUALLY DIMINISH TOWARDS SUNRISE
WED.
ONE AREA THAT SHOULD BE WATCHED IS THE UNCOMPAHGRE GORGE AT AND
NEAR OURAY CO. THIS AREA COULD PICK UP SOME DECENT ACCUMULATIONS
AS THE FLOW TURNS AROUND TO NORTH LATER TODAY THROUGH THIS
EVENING. HOWEVER...I CHOSE NOT TO INCLUDE CO ZONE 18 IN THE
ADVISORY AS THE DURATION WILL BE SHORT...AND THE HEAVIER
ACCUMULATIONS ARE EXPECTED TO BE LOCALIZED.
ANY REMAINING SHOWERS IN THE NORTHERN MOUNTAINS WILL QUICKLY WIND
DOWN THROUGH THE MORNING ON WED...WITH ONLY A FEW LINGERING BEYOND
MIDDAY NEAR THE CONTINENTAL DIVIDE.
BELOW NORMAL TEMPERATURES WILL CONTINUE.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 355 AM MST TUE FEB 26 2013
RIDGE AMPLIFIES OVER THE WEST COAST STATES WEDNESDAY NIGHT INTO
THURSDAY NIGHT...BUT THE GFS AND TO A LESSER EXTENT THE SREF
INDICATE A DISTURBANCE WILL STREAM OVER THE NRN DIVIDE MOUNTAINS FOR
A CHANCE OF SNOW. THE ECMWF APPEARS TO BE TRENDING THIS DIRECTION
SO THE CHANCE POPS APPEAR WARRANTED. THIS WOULD BE A FAST MOVING
DISTURBANCE AND ANY SNOWFALL WILL BE LIGHT.
IN THE BIGGER PICTURE...A WARMING TREND WILL OCCUR THIS UPCOMING
WEEKEND AS A WARM RIDGE MOVES EAST ACROSS THE INTERMOUNTAIN WEST AND
ROCKY MOUNTAIN STATES ON SATURDAY AND SUNDAY. EXPECT WARMING TEMPS
AT ALL LOCATIONS...OR SLIGHTLY ABOVE AVERAGE COMPARED TO CLIMO.
RECENT TEMPS HAVE BEEN BELOW NORMAL...SO THIS WARMING WILL FEEL MORE
SIGNIFICANT THAN COMPARED TO CLIMO.
FORECAST CONFIDENCE DIMINISHES SUNDAY NIGHT AND MONDAY AS A
SIGNIFICANT SHORT WAVE PUNCHES ACROSS THE PACIFIC NORTHWEST AND NRN
INTERMOUNTAIN REGION. SOME ENTRAINMENT OF SUBTROPICAL MOISTURE IS
POSSIBLE AHEAD OF THIS FEATURE...AND THIS COULD LEAD TO CHANCE OF
PRECIPITATION SUNDAY NIGHT. MONDAY BECOMES MORE MURKY AS THE ECMWF
SHOWS MUCH COLDER AIR SPILLING INTO THE FORECAST AREA. WOULD LIKE
TO SEE SOME CONFIRMATION BY THE GFS OR RUN TO RUN CONTINUITY BY THE
EURO MODEL. WILL NOT MAKE TOO MANY CHANGES FROM THE CONSENSUS
OUTPUT...BUT DID LOWER MAX TEMPS ACROSS THE NWRN COLORADO VALLEYS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 355 AM MST TUE FEB 26 2013
SNOW OVER THE NORTHERN AND CENTRAL MOUNTAINS EARLY THIS MORNING
WILL SPREAD INTO THE SOUTHERN MOUNTAINS BY AROUND 14Z...AND THEN
QUICKLY BECOME WIDESPREAD.
AN UPPER LEVEL TROUGH WILL PASS OVER THE AREA FROM 12Z/TUE TO
00Z/WED. AS A RESULT...AIRFIELDS WILL LIKELY SEE PERIODS OF MVFR
CIGS AND VSBY WITH BRIEF IFR CONDITIONS POSSIBLE IN HEAVIER
SHOWERS. PERSISTENT MOIST NORTHWESTERLY FLOW WILL FAVOR PROLONGED
PERIODS OF SNOW AT AIRPORTS EAST OF A 2OW KCAG-KMTJ LINE DURING
THE AFTERNOON. IN CONTRAST...NORTHWEST WINDS ARE UNFAVORABLE FOR
THE SOUTHERN AIRPORTS...SPECIFICALLY KCEZ...KDRO AND KPSO WHICH
WILL EXPERIENCE DRY DOWNSLOPE FLOW THROUGHOUT THE DAY. THE
MOUNTAINS WILL BE OBSCURED THROUGH 06Z WITH GUSTY NORTHWEST WINDS
AT TIMES RESULTING IN MECHANICAL TURBULENCE IN THE LEE OF PEAKS
AND RIDGES. MOUNTAIN SNOW WILL DIMINISH AFTER 06Z...BUT SNOW
SHOWERS WILL CONTINUE ALONG NORTHWEST-NORTH FACING SLOPES OF THE
NORTH AND WEST-CENTRAL COLORADO MOUNTAINS. THEREFORE MOUNTAIN
OBSCURATIONS WILL CONTINUE ALONG THESE SLOPES.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL 9 AM MST WEDNESDAY FOR COZ004-009-
010-013.
UT...NONE.
&&
$$
UPDATE...PF
SHORT TERM...EH
LONG TERM...PF
AVIATION...EH
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
210 PM EST TUE FEB 26 2013
.SYNOPSIS...
AN OCCLUDED FRONT WILL MOVE THROUGH THE FORECAST AREA LATE THIS
AFTERNOON. DRYING WILL OCCUR BEHIND THIS FRONT FOR TONIGHT. THE
ASSOCIATED STRONG LOW PRESSURE CENTER WILL BE NORTH OF THE
FORECAST AREA THROUGH THURSDAY AND RESULT IN BREEZY CONDITIONS IN
OUR AREA.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE COOL AND STABLE AIR WAS WELL ENTRENCHED IN THE NORTH AND WEST
SECTIONS OF THE FORECAST AREA. THE WARM FRONT WAS CLOSE TO THE
SOUTHEAST PART. TEMPERATURES RANGED FROM NEAR 40 IN THE NORTH TO
AROUND 50 IN THE SOUTH. THE MAIN H85 WARM ADVECTION PATTERN AND
WIDESPREAD RAIN HAS SHIFTED NORTHEAST OF THE FORECAST AREA. THE
MAIN FORECAST PROBLEM IS HOW FAR NORTHWARD AND INLAND THE WARM
FRONT WILL MOVE. SOME BREAKS IN THE CLOUDINESS WERE OCCURRING NEAR
THE EXTREME SOUTHEAST PART INDICATING THE WARM FRONT MAY GET INTO
THAT AREA. SATELLITE TRENDS INDICATED THE MID- LEVEL DRY SLOT WILL
MOVE INTO THE AREA THIS AFTERNOON WITH ITS ASSOCIATED ENHANCED
INSTABILITY. STRONG SHEAR CONTINUES OVER THE AREA. THE KCAE 88D
SHOWED 2000 FOOT WINDS NEAR 35 KNOTS. THE SHEAR AND POSSIBLE
DEVELOPMENT OF SURFACE-BASED INSTABILITY SUPPORTS A POSSIBILITY OF
SEVERE THUNDERSTORMS MAINLY NEAR THE WARM FRONT IN THE SOUTHEAST
PART.
WEDGE WILL ERODE FROM SOUTH TO NORTH DURING THE EVENING AS SURFACE
LOW MOVES NORTHEAST OF THE REGION AND SOUTHWEST LOW LEVEL FLOW
DEVELOPS. EXPECT PARTLY CLOUDY SKIES TO DEVELOP...COULD BE LATE
IN THE NORTHERN MIDLANDS THOUGH. WINDS IN THE BOUNDARY LAYER WINDS 10 TO
20 KTS AND WITH MIXING SO EXPECT TEMPERATURES TO STAY UP DESPITE
DRY AIR ADVECTION. WITH WARMER LAKE TEMPERATURES GUSTY WINDS
PROBABLY WILL DEVELOP ON THE AREA LAKES OVERNIGHT SO WILL POST
LAKE WIND ADVISORY. MOS TEMPERATURES LOOK OK.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AIR MASS DRYING OUT THROUGH THE PERIOD. WARM ADVECTION NOTED
WEDNESDAY EXPECT TEMPERATURES CLOSER TO NORMAL...IN THE LOW TO MID
60S. TIGHT SURFACE PRESSURE GRADIENT SO EXPECT GUSTY WINDS
ESPECIALLY IN THE AFTERNOON WILL CONTINUE LAKE WIND ADVISORY
THROUGH SUNSET. LAKE WIND MAY NEED TO BE EXTENDED INTO THURSDAY AS RE-
ENFORCING COLD FRONT MOVES THROUGH WEDNESDAY NIGHT. ALTHOUGH COLD
ADVECTION THURSDAY...OFFSETTING STRONG DOWNSLOPE FLOW EXPECTED BUT WILL
FORECAST TEMPERATURES COOLER THAN WEDNESDAY...SLIGHTLY BELOW MOS CONSENSUS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
SEVERAL SHORT WAVES MOVING THROUGH THE REGION IN BROAD UPPER
LEVEL CYCLONIC FLOW BUT MOISTURE SHOULD BE LIMITED. LATEST GFS AND
ECMWF SHOW AN UPPER LOW MOVING OVER THE AREA SATURDAY/SATURDAY
NIGHT WITH LIMITED MOISTURE TO WORK WITH. POP GUIDANCE NEAR
CLIMATOLOGY BUT NOTICEABLE SPIKE UP IN POPS. SOUNDING ANALYSIS
SUGGEST MOISTURE WILL BE QUITE SHALLOW ACROSS MOST OF THE
MIDLANDS. ICE CRYSTAL GROWTH NOT LIKELY...GFS SUGGESTS BETTER
CHANCE OF WINTER WEATHER NORTH. ECMWF IS DRIER. WILL MENTION
SLIGHT CHANCE SHOWERS OR SNOW SHOWERS MAINLY SATURDAY NIGHT AND
EARLY SUNDAY IN THE PIEDMONT AND NORTH MIDLANDS...OTHERWISE WILL
CONTINUE DRY FORECAST. TEMPERATURES BELOW NORMAL.
&&
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
THE COOL AND MOIST WEDGE PATTERN WAS IN PLACE EARLY THIS AFTERNOON
WITH WIDESPREAD IFR CONDITIONS. ABOVE THE WEDGE THE CAE 88D WAS
INDICATING 2000 FOOT WINDS AROUND 35 KNOTS. WE HAVE INCLUDED LLWS IN
THE TERMINAL FORECASTS. MIXING BEHIND THE OCCLUDED FRONT SHOULD
BRING IMPROVING CONDITIONS FROM SOUTHWEST TO NORTHEAST. SATELLITE
TRENDS SUPPORT THE IMPROVEMENT IN THE CENTRAL SAVANNAH RIVER AREA.
IMPROVEMENT MAY NOT OCCUR FARTHER NORTH UNTIL THE EVENING AS
INDICATED BY THE LATEST HRRR FLIGHT CATEGORY FORECAST AND GFS LAMP.
DRYING SHOULD EVENTUALLY BECOME DOMINATE ACROSS ALL OF THE AREA
TONIGHT. DESPITE LOW-LEVEL MOISTURE ASSOCIATED WITH THE RECENT RAIN
FOG APPEARS UNLIKELY DURING THE EARLY MORNING HOURS BECAUSE OF WIND
AND DRYING. THE PRESSURE GRADIENT ASSOCIATED WITH STRONG LOW PRESSURE
NORTH OF THE AREA WILL SUPPORT BREEZY CONDITIONS WEDNESDAY. MODEL
TIME-HEIGHT DISPLAYS AND EXPECTED MIXING SUPPORT GUSTS NEAR 24 KNOTS.
.EXTENDED AVIATION OUTLOOK...
STRONG LOW PRESSURE CENTERED NORTH OF THE AREA WILL BRING BREEZY
CONDITIONS DURING THE REST OF WEDNESDAY AND THURSDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...LAKE WIND ADVISORY FROM 6 PM THIS EVENING TO 7 PM EST
WEDNESDAY FOR SCZ015-016-018-020>022-025>028.
LAKE WIND ADVISORY UNTIL 7 PM EST WEDNESDAY FOR SCZ029>031-
035>038-041.
GA...LAKE WIND ADVISORY FROM 6 PM THIS EVENING TO 7 PM EST
WEDNESDAY FOR GAZ040-063-064.
LAKE WIND ADVISORY UNTIL 7 PM EST WEDNESDAY FOR GAZ065-077.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
347 PM CST TUE FEB 26 2013
.SHORT TERM /TONIGHT/...
WINTER STORM WILL PERSIST THROUGH WEDNESDAY MORNING AS LIGHT TO
MODERATE SNOW BANDING CONTINUES ON THE BACKSIDE OF THE SURFACE LOW
LOCATED IN SOUTHEAST MISSOURI. SURFACE LOW LOOKS TO SLOWLY MIGRATE
NORTHEAST FROM SOUTHEAST MISSOURI INTO CENTRAL ILLINOIS THIS EVENING
INTO TOMORROW MORNING. LEANED TOWARD A SREF/GFS/NAM12 BLEND FOR
TRENDS TONIGHT.
WEAK LIFT WITHIN THE DENDRITIC GROWTH ZONE CONTINUES THIS AFTERNOON
AND TONIGHT...AND EVEN PERSISTS INTO WEDNESDAY MORNING. HIGHER
CONFIDENCE WITH THE ADDITIONAL LIGHT SNOW AMOUNTS THROUGH WEDNESDAY
MORNING RESULTING IN ROUGHLY 1 TO 4 INCHES OF ADDITIONAL SNOW
THROUGH 12Z ACROSS THE WARNING AREA. THE SNOW BAND AXIS LOOKS TO
CONTINUE TO SLOWLY PIVOT COUNTERCLOCKWISE AROUND THE CENTRAL PORTION
OF THE FORECAST RESULTING IN SOME AREAS RECEIVING AN ELONGATED
PERIOD OF MODERATE TO BRIEF HEAVY SNOW THIS EVENING. WITH THE
CURRENT TRACK OF THE SURFACE LOW...NOT EXPECTING THIS BAND TO DRIFT
SOUTHEAST ALL THAT MUCH UNTIL EARLY WEDNESDAY MORNING.
GENERALLY EXPECTING A HALF TO POSSIBLY ONE INCH PER HOUR SNOWFALL
RATES THIS EVENING WITH THE WEAK LIFT IN THE DENDRITIC LAYER. SREF
100MB/50MB DENDRITE GROWTH ZONE PARAMETER DEPICTING 80-90 PERCENT
PROBABILITY OF DENDRITIC SNOW THROUGH TOMORROW AND MATCHES UP WELL
WITH PREVIOUSLY MENTION BAND PIVOTING ACROSS CENTRAL IOWA. BUFR
SOUNDINGS REMAIN DEEPLY SATURATED THROUGH WEDNESDAY MORNING...WITH
THE RAP SHOWING A MID LEVEL DRY LAYER ADVECTING INTO DSM TO ALO AND
MAY SEE A BRIEF BREAK IN THE SNOW MID TO LATE EVENING.
WINDS ATOP THE MIXED LAYER RANGE FROM 25 TO 30KTS THIS AFTERNOON AND
TONIGHT AND EXPECTING BLOWING SNOW IMPACTS TO CONTINUE AS WELL.
LEANED TOWARDS THE GFS/SREF QPF AMOUNTS TONIGHT AS NAM SEEMS TO HIGH
ACROSS THE EAST...ESPECIALLY WITH THE WEAKER FORCING.
.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
WEAKER LIFT WILL PERSIST INTO WEDNESDAY WITH THE SPC SREF INDICATING
DEEP DENDRITIC GROWTH LAYER CONTINUING THROUGH CENTRAL IOWA. ALL
SOUNDINGS CONTINUE TO ALSO SHOW DEEP SATURATION THROUGH AT LEAST
MIDDAY TOMORROW AND ANTICIPATE THE LIGHT SNOW TO CONTINUE. HAVE
GONE WITH LIKELY TO CATEGORICAL POPS FOR MUCH OF THE AREA UNDER THE
CURRENT HEADLINE WITH THE SHARP CUTOFF ON THE NORTHERN SIDE OF THE
PCPN AREA PERSISTING. WINDS WILL REMAIN RATHER STRONG THROUGH THE
DAY WITH BRISK NORTHWEST FLOW PERSISTING WITH DECENT PRESSURE
GRADIENT. EVENTUALLY...THE FORCING WILL BE DIMINISHING WITH THE
SNOW TAPERING TO FLURRIES BY LATER IN THE DAY. CLOUDINESS IS
EXPECTED TO PERSIST AS WELL IN CYCLONIC FLOW ON BACKSIDE INTO
WEDNESDAY NIGHT WITH AN APPROACHING SHORTWAVE ON THURSDAY AND
THURSDAY NIGHT HELPING THE CLOUDINESS TO MAINTAIN. IN FACT...SOME
WEAK LIFT WITH THIS PASSING WAVE ON FRIDAY MAY HELP TO PRODUCE SOME
FLURRIES IN SOUTHERN IOWA DURING THE DAY.
UPPER RIDGING WILL SLIDE THROUGH THE REGION INTO THE WEEKEND WITH
QUIET WEATHER DURING THIS TIME. TEMPERATURES WILL REMAIN BELOW
NORMAL WITH WIDESPREAD SNOW PACK AND ONLY WEAK ADVECTION UNTIL
SUNDAY NIGHT. THIS WARM ADVECTION IS IN ADVANCE OF THE NEXT SYSTEM
WHICH WILL PASS THROUGH THE REGION ON MONDAY INTO TUESDAY IN BROAD
NORTHWEST FLOW. BOTH GFS AND EURO HAVE INDICATED SOME DECENT
FORCING AND ANTICIPATE PCPN DEVELOPING AND SLIDING ACROSS THE STATE
ON MONDAY INTO EARLY TUESDAY. SOUNDINGS WOULD INDICATE GENERALLY
SNOW DURING THIS TIME ACROSS THE STATE WITH LIGHT TO MODERATE
ACCUMULATIONS EXPECTED.
&&
.AVIATION 26/18Z...
MODERATE TO HEAVY BAND WILL CONTINUE TO PRESS WEST THROUGH THE
AFTERNOON HOURS. BRIEF BREAK AT DSM WRT TO VIS...BEFORE SPREADING
BACK IN BY AROUND 21Z. EXPECTING THE HEAVIEST BAND TO SKIRT ACROSS
FOD THROUGH 22Z THIS AFTERNOON AND HAVE IFR VIS MENTIONED THROUGH
THEN. ALO WILL SEE PERIODIC SHIFTS FROM IFR TO MVFR THROUGH THE
AFTERNOON. LATEST MODEL RUNS KEEP LIGHT TO LOCALLY MODERATE SNOW
THROUGH MUCH OF THE EVENING INTO EARLY WEDNESDAY MORNING...MAINLY
EXPECTING MVFR CONDITIONS WITH SOME BRIEF IFR CONDITIONS DUE TO
VIS/CIGS OVERNIGHT.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL NOON CST WEDNESDAY FOR
ADAIR-ADAMS-APPANOOSE-BLACK HAWK-BOONE-CLARKE-DALLAS-DAVIS-
DECATUR-GRUNDY-HARDIN-JASPER-LUCAS-MADISON-MAHASKA-MARION-MARSHALL-
MONROE-POLK-POWESHIEK-RINGGOLD-STORY-TAMA-TAYLOR-UNION-WAPELLO-
WARREN-WAYNE.
WINTER WEATHER ADVISORY UNTIL NOON CST WEDNESDAY FOR
AUDUBON-BREMER-BUTLER-CASS-FRANKLIN-GREENE-GUTHRIE-HAMILTON.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...COGIL
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1139 PM CST MON FEB 25 2013
.UPDATE...
ADDED 06Z TAF DISCUSSION. ALSO ISSUED SPS TO HIGHLIGHT REDUCED
VSBYS OVER W CENTRAL TO N CENTRAL IA. BRIDGE AND ROAD SURFACE TEMPS
ARE APPROACHING DEWPOINTS AS WELL...SO FELT PATCHY FROST MAY ALSO
FORM ON BRIDGES AND OVERPASSES. COMBINATION OF GRADUALLY INCREASING
WINDS...STRATUS...AND MID/CLOUDS SPREADING NWD WILL KEEP CONDITIONS
FROM DETERIORATE TOO MUCH. SHOULD STAY ABOVE ADVISORY CRITERIA IN
SPACE AND MAGNITUDE.
PREVIOUS UPDATE...NO CHANGES TO HEADLINES OR FORECAST THIS EVENING.
18Z GUIDANCE HAD A POOR HANDLE ON SITUATION WITH MO/AR CONVECTION
STRONGER AND FARTHER EAST THAN ANTICIPATED. THIS LIKELY RESULTING
IN MODELS INCORRECTLY HANDLING THE LATENT HEAT/PV BUDGETS WITH
QUESTIONABLE RESULTS. 18Z NAM WAS DEFINITELY ONE OF THOSE LACKING
AND THE 00Z RUN SEEMS BEHIND BRINGING TROWEL PRECIP INTO KC METRO
AREA RIGHT NOW. SO WITH LITTLE NEW TRUSTED GUIDANCE
AVAILABLE...WILL LEAVE CURRENT FORECAST AND HEADLINES RIDE. SHORTER
TERM 00Z HRRR DOES SEEM TO HAVE A GRASP ON REALITY AND BRINGS PRECIP
INTO SRN IA OVERNIGHT...ANOTHER REASON TO LEAVE THINGS AS IS.
&&
.SHORT TERM /TONIGHT/...
LOW PRESSURE NOW DEEPENING OVER ARKANSAS THIS AFTERNOON. THE
SYSTEM WILL LIFT VERY SLOWLY NORTHEAST OVERNIGHT AND WILL BEGIN
TO INCH INTO FAR SOUTHERN MISSOURI BY 12Z. THE UPPER LEVEL LOW IS
BACK TO THE WEST OVER OKLAHOMA AND TEXAS AND WILL BECOME NEARLY
STACKED WITH THE SFC FEATURE BY 12Z. THE PRESSURE GRADIENT WILL
INCREASE OVER IOWA OVERNIGHT AND WILL INCREASE NORTHERN SURFACE
WINDS ACROSS THE STATE. THE SOURCE REGION FOR THESE WINDS WILL BE
FROM HIGH PRESSURE OVER MINNESOTA AND WISCONSIN WHICH WILL
CONTINUE TO FUNNEL DRIER AIR INTO THE STATE. AS THIS OCCURS...MID
LEVEL THETA-E ADVECTION WILL LIFT NORTH INTO SOUTHERN IOWA. THE
INFILTRATION OF THE DRIER AIR WILL DELAY THE ONSET OF SNOW ACROSS
THAT REGION. THERE IS SOME POTENTIAL FOR SATURATION TO OCCUR OVER
FAR SOUTH CENTRAL TO SOUTHWEST IOWA TO SATURATE TOWARD 06Z.
POTENTIAL FOR UP TO ONE INCH OF SNOW IN THESE AREAS. ELSEWHERE
WILL REMAIN DRY THROUGH THE PERIOD.
AREAS OF FOG LINGERED ACROSS NORTHWEST IOWA THROUGH THE DAY.
POSSIBLE THAT VISIBILITIES WILL LOWER A BIT OVERNIGHT THROUGH
EXPECT THE INCREASING NORTHERLY FLOW OVERNIGHT WILL IMPROVE
CONDITIONS THROUGH THE PERIOD.
.LONG TERM /TUESDAY THROUGH SUNDAY/...
MAIN FORECAST CONCERN IS WITH UPPER LOW STRENGTHENING AS IT MOVES
ACROSS THE CENTRAL/SOUTHERN PLAINS TONIGHT THROUGH WEDNESDAY. MODELS
HAVE TRENDED ON A FURTHER SOUTHEAST TRACK AS SURFACE HIGH REMAINS A
STRONGHOLD OVER THE WESTERN GREAT LAKES DURING THE DAY TUESDAY.
LEANED TOWARD A SREF/GFS BLEND AND THE 12Z ECMWF AS THESE MODELS ARE
IN GOOD AGREEMENT WITH ONE ANOTHER. NAM HAS COMPLETELY SHIFTED THE
LOW TRACK FURTHER SOUTHEAST COMPARED TO PREVIOUS RUNS AND HAD LOW
CONFIDENCE WITH THIS SOLUTIONS DUE TO DISCONTINUITY.
TUESDAY THROUGH WEDNESDAY...NEAR VERTICALLY STACKED LOW WILL TRACK
ACROSS THE OZARKS INTO OHIO VALLEY THROUGHOUT THE DAY TUESDAY AND
TUESDAY NIGHT. A SECONDARY SHORTWAVE QUICKLY MOVES ACROSS NORTHERN
MISSOURI TUESDAY NIGHT INTO WEDNESDAY. BEST FRONTOGENETICAL FORCING
REMAINS JUST ALONG THE IOWA/MISSOURI BY 12Z TO 18Z TUESDAY...THEN
LOOKS TO BE AN ELONGATED PERIOD OF LIGHT TO MODERATE SNOW. MAX OMEGA
WITHIN THE DENDRITIC ZONE MATCHES UP WELL LATE TUESDAY MORNING INTO
THE EARLY AFTERNOON HOURS ACROSS FAR SOUTHEAST IOWA...THEN WEAKENS
BY THE AFTERNOON AND EVENING. SECOND SHORTWAVE WILL BRING
REINFORCEMENT OF LIFT AND MOISTURE AND LOOKS TO PROLONG THE SNOWFALL
INTO EARLY WEDNESDAY. OTHER CONCERN IS WITH STRONG SURFACE WINDS AS
PRESSURE GRADIENT REALLY TIGHTENS THROUGHOUT THE DAY TOMORROW AND
CONTINUES INTO WEDNESDAY MORNING. WINDS AT 925MB ARE ROUGHLY 35KTS
THROUGH MUCH OF THE DAY TUESDAY THEN DECREASING SOMEWHAT TOMORROW
NIGHT INTO WEDNESDAY. SHARP GRADIENT WRT TO SNOW AMOUNTS SETS UP
ACROSS SOUTHEAST IOWA WITH THE DRY AIR ADVECTING IN FROM THE NORTH.
CONFIDENT THOUGH THE SOUTHEAST WILL SEE A 4 TO 6 INCH RANGE
COMBINED WITH THE STRONG WINDS...LEANED TOWARD WINTER STORM
WARNING.
THURSDAY THROUGH SUNDAY...NO MAJOR CHANGES WITH EXTENDED PERIOD AS
HIGH PRESSURE REMAINS IN CONTROL THROUGH THE WEEKEND. A GRADUAL
WARM UP BEGINS BY THE WEEKEND INTO EARLY NEXT WEEK.
&&
.AVIATION...26/06Z
CONDITIONS DETERIORATE FROM VFR SE /KOTM/ TO MVFR CENTRAL SECTIONS
/KDSM/KFOD/KALO/ TO IFR AND LIFR WEST AND N CENTRAL /KMCW/. THESE
RESTRICTIONS ARE DUE TO FOG AND STRATUS AND SHOULD REMAIN FAIRLY
STATIC THROUGH DAYBREAK. HOWEVER LARGE SYSTEM JUST TO OUR SOUTH
WILL EVENTUALLY SPREAD SNOW INTO CENTRAL AND SOUTHERN IOWA WITH SNOW
VSBYS AND CIGS DROPPING CONDITIONS TO IFR VSBYS AND POTENTIALLY CIGS
SOUTH...MAINLY AT KOTM. THIS SHOULD LAST INTO THE EVENING TO VARIED
DEGREES. MODELS ARE STILL NOT HANDLING THIS SYSTEM WELL HOWEVER SO
CONFIDENCE IN TIMING AND NWD EXTENT OF DEGRADED CONDITIONS IS NOT
THE GREATEST.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 9 AM TUE TO 6 AM WED
CLARKE-DECATUR-LUCAS-MAHASKA-MARION-MONROE-RINGGOLD-WAPELLO-WAYNE
WINTER STORM WARNING FROM 9 AM TUE TO 6 AM CST WED APPANOOSE-DAVIS
&&
$$
UPDATE/AVIATION...SMALL
SHORT TERM...DONAVON
LONG TERM...PODRAZIK
AREA FORECAST DISCUSSION
NWS TOPEKA KS
555 PM CST WED FEB 27 2013
...UPDATE TO AVIATION...
.DISCUSSION...
TONIGHT THROUGH TOMORROW...
DECREASING LOW CLOUDS AND WINDS WILL BE THE MAIN SHORT TERM WEATHER
CONCERN THROUGH TOMORROW. MOST AREAS HAVE SEEN THE LOWER LAYER OF
CLOUDS MOVE EAST...LEAVING JUST CIRRUS CLOUDS IN PLACE. STILL ENOUGH
WIND OVERNIGHT TO KEEP TEMPERATURES FROM PLUNGING OVER NEW
SNOWPACK...AND THIS WILL ALSO PRECLUDE ANY SIGNIFICANT FOG
FORMATION. WINDS WILL INCREASE AGAIN TOMORROW WITH GOOD MIXING...BUT
NOT NEARLY TO THE EXTENT AS TODAY. INCREASING MID CLOUDS FROM THE
NORTHWEST WILL BE EVIDENT TOMORROW AFTERNOON IN WESTERN AND CENTRAL
KANSAS...WITH NO SENSIBLE WEATHER ASSOCIATED WITH THEM.
HARDING
THURSDAY NIGHT THROUGH SATURDAY...
NEXT CHANCE OF ANY TYPE OF MOISTURE APPEARS TO BE ASSOCIATED WITH
A WEAK UPPER DISTURBANCE...BEST SEEN AS AN UPPER PV
ANOMALY...MOVING SOUTHWARD ACROSS EASTERN KS ON FRIDAY.
HOWEVER...MOISTURE LACKING AND SYSTEM MOVING QUICKLY SO AT MOST A
FEW FLURRIES LOOK POSSIBLE WITH THIS WEAK WAVE.
INTERESTINGLY...THE 12Z GFS BRINGS ANOTHER SHORTWAVE TROUGH
SOUTHWARD ON SATURDAY...SQUEEZING OUT A FEW HUNDREDTHS OF QPF IN
THE FORM OF SNOW. HOWEVER...LOOKING AT THE OTHER SHORT AND MEDIUM
RANGE MODELS SHOWS THE GFS AS THE OUTLIER AND THUS HAVE
DISREGARDED THAT FORECAST.
AFTER THAT...MEDIUM RANGE MODELS ARE SIMILAR IN MOVING A WELL
DEFINED UPPER LOW ACROSS NEBRASKA MONDAY AND INTO THE NORTHERN
MO/SOUTHERN IA REGION BY TUESDAY MORNING. MAIN DYNAMICS WITH SUCH
A SYSTEM WILL BE TO THE NORTH OF KS. POTENTIAL FOR SOME WARM
ADVECTION LIFT AHEAD OF THIS WAVE...AND WRAPAROUND BEHIND THE
UPPER LOW GIVE SMALL CHANCES FOR LIGHT RAIN OR LIGHT SNOW MONDAY
NIGHT INTO EARLY TUESDAY. HOWEVER..SINCE MODELS HAVE BEEN
TRENDING NORTHWARD WITH THIS SYSTEM WITH TIME...NEXT FORECAST
PACKAGE MAY HAVE CHANCES FOR THIS LIGHT PRECIP CONFINED TO EXTREME
NORTHERN KS.
SHOULD BE A GENERAL WARMING TREND FROM THE WEEKEND INTO THE MIDDLE
OF NEXT WEEK...BUT WARMUP WILL BE TEMPERED BY HOW QUICKLY THE SNOW MELTS.
GDP
&&
.AVIATION...
VFR CONDITIONS EXPECTED TO CONTINUE THROUGH 10Z THEN SOME MVFR
CIGS MAY MOVE INTO THE TERMINALS. MODELS OVERDOING THE 925 MB RH
AT 00Z TODAY AS LATEST UPPER AIR SOUNDING MUCH DRIER THAN THE
NAM AND RAP FORECAST SOUNDINGS AT 00Z. WILL BRING A SCT-BKN MVFR
CIGS IN AT TOP MHK AND FOE AFTER 10Z THROUGH 14Z THEN VFR AFTER
15Z. WINDS WILL REMAIN UP NEAR 10 TO 12KTS THROUGH THE PERIOD
KEEPING LOWER BOUNDARY LAYER MIXED AND VERY SMALL CHANCES OF FOG.
53
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS JACKSON KY
1232 PM EST TUE FEB 26 2013
.UPDATE...
ISSUED AT 1126 AM EST TUE FEB 26 2013
JUST A MINOR UPDATE WAS NECESSARY WITH THIS MORNINGS FORECAST.
SEVERAL AREAS OF CLEARING APPEARED EARLIER THIS MORNING IN THE
EXTENSIVE CLOUD SHIELD THAT HAS BEEN OVERSPREADING KENTUCKY SINCE
LATE LAST NIGHT. THE SKY COVER GRIDS WERE UPDATED TO TRACK THESE
AREAS OF CLEARING ACROSS THE FORECAST AREA AND INTO VIRGINIA AND WEST
VIRGINIA OVER THE NEXT SEVERAL HOURS. THE PRECIPITATION PROBABILITY
FORECAST WAS ALSO UPDATED TO REFLECT THE SCATTERED SHOWER ACTIVITY
THAT HAS PERSISTED THROUGHOUT THE MORNING. IT STILL APPEARS THAT MORE
NUMEROUS RAIN SHOWERS AND PERHAPS A THUNDERSTORM OR TWO WILL OCCUR
THROUGHOUT THE AFTERNOON...BEFORE THINGS TAPER OFF DURING THIS
EVENING. THE CORRESPONDING WEATHER TYPE AND QPF GRIDS WERE ALSO
REFORMULATED TO ACCOUNT FOR THE UPDATED PRECIPITATION PROBABILITY
FORECAST. ALSO REMOVED MORNING AND AFTERNOON WORDING FROM THE ZONE
FORECAST TEXT PRODUCT TO FRESHEN THINGS UP.
UPDATE ISSUED AT 652 AM EST TUE FEB 26 2013
DOWNSLOPING WINDS HAVE DEFINITELY TAKEN ITS TOLL ON THE RAIN AS IT
HAS PUSHED ACROSS THE AREA. MOST PLACES ARE GETTING LUCKY JUST TO
SQUEEZE OUT A HUNDREDTH OF AN INCH OF RAIN. THUS...HAVE DECIDED TO
TRIM POPS BACK...ESPECIALLY ACROSS THE SOUTH WHERE THINGS ARE ALREADY
STARTING TO DRY OUT. WITHIN THE NEXT FEW HOURS...ALL OF THE RAIN
SHOULD DEPART OFF TO THE NORTH...LEAVING BEHIND MAINLY DRY CONDITIONS
FOR THE BALANCE OF THE MORNING. HOWEVER...ANOTHER ROUND OF SHOWERS
STILL LOOKS ON TAP FOR THIS AFTERNOON...AS ANOTHER BAND OF SHOWERS
PUSHES EAST ACROSS THE AREA. THIS TIME THINGS MAY BE MORE CONVECTIVE
IN NATURE WITH THE THREAT OF STRONG WINDS AND SMALL HAIL STILL A
THREAT. LATEST HRRR DEFINITELY SUPPORTS SOME STRONG
SHOWERS/THUNDERSTORMS DEVELOPING BY EARLY AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 320 AM EST TUE FEB 26 2013
UPPER LEVEL LOW WILL CONTINUE TO PUSH INTO THE OHIO RIVER VALLEY
TODAY WITH AN OCCLUDING FRONTAL BOUNDARY CONTINUING TO LIFT NORTH
ACROSS THE AREA THIS MORNING. A BAND OF RAIN SHOWERS WILL PUSH NORTH
THROUGH THE EARLY MORNING HOURS. DOWNSLOPING SOUTHEAST WINDS WILL
CONTINUE TO TRY TO EAT AWAY AT THIS RAIN AS IT MOVES ACROSS THE AREA.
THIS WILL KEEP OVERALL RAINFALL AMOUNTS ON THE LIGHT SIDE...BUT WE
SHOULD SEE JUST ABOUT EVERYONE MEASURE BY 13Z. THIS BAND WILL QUICKLY
DEPART TO THE NORTH SHORTLY AFTER DAYBREAK...WITH ONLY SOME ISOLATED
TO SCATTERED SHOWERS LINGERING NEAR THE I-75 CORRIDOR. DOWNSLOPING
WINDS WILL LIKELY KEEP MOST OF THE ACTIVITY CLOSER TO CENTRAL
KENTUCKY. EVENTUALLY WINDS WILL VEER AROUND TO THE SOUTH OR SOUTHWEST
THIS AFTERNOON AS ANOTHER IMPULSE RIDES NORTHEAST ACROSS THE AREA.
THIS WILL TRIGGER ANOTHER ROUND OF SCATTERED TO NUMEROUS SHOWERS. IN
ADDITION...INSTABILITY REMAINS QUITE IMPRESSIVE...SO CANNOT RULE OUT
SOME ISOLATED THUNDERSTORMS WITH PERHAPS SOME SMALL HAIL. FINALLY A
THIRD WAVE WILL RIDE NORTHEAST ACROSS THE AREA THIS
EVENING...GENERATING SOME MORE SCATTERED SHOWERS. BY THIS
EVENING...INSTABILITY WILL DEPART TO THE NORTH...SO NO THUNDER
THROUGH THE EVENING HOURS. AS WINDS VEER TO THE SOUTHWEST
TONIGHT...LOWER CIGS MAY OVERSPREAD THE AREA...POSSIBLY LEADING TO
SOME PATCHY DRIZZLE LATE TONIGHT. HOWEVER...UNCERTAINTY EXISTS WITH
HOW MUCH LOW LEVEL MOISTURE WILL DEVELOP WHICH WOULD BE NEEDED TO
ACHIEVE ANY DRIZZLE. FINALLY...AS THE UPPER LEVEL LOW CONTINUES TO
ROTATE EASTWARD ACROSS THE OHIO RIVER VALLEY ON WEDNESDAY...THIS
SYSTEM WILL SEND A VIGOROUS SHORTWAVE SOUTHEAST ACROSS THE
AREA...GIVING WAY TO ANOTHER ROUND OF RAIN. COLDER AIR WILL ALSO
SETTLE SOUTHWARD AND AS WE WETBULB THROUGH THE EVENING...WE SHOULD
SEE SOME SNOW STARTING TO MIX IN AS WE HEAD INTO THE EVENING HOURS.
AS FOR THE WIND ADVISORY...GOING TO LEAVE THE COUNTIES NEAR THE
VIRGINIA BORDER IN THE ADVISORY. THE MESONET STATION AT DORTON IS HAS
GUSTED UP TO 38 MPH AND THIS SHOULD ONLY GO HIGHER AS THE SYSTEM
MOVES TOWARDS US TODAY.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 350 AM EST TUE FEB 26 2013
THE MODELS ARE IN RELATIVELY GOOD AGREEMENT ALOFT THROUGH THE FIRST
PART OF THE EXTENDED...ESPECIALLY CONSIDERING THE AMPLIFIED NATURE OF
THE PATTERN. A DEEP AND LARGE CLOSED LOW WILL SLOWLY ROLL OUT OF THE
OHIO VALLEY ON THURSDAY WITH THE GFS RUNNING SLIGHTLY FASTER THAN THE
ECMWF. IN THE WAKE OF THIS...A STEADY STREAM OF UNCONSOLIDATED ENERGY
WILL SLIP THROUGH THE REGION INTO FRIDAY WHILE THE WESTERN EXTENT OF
IT STARTS TO CARVE OUT ANOTHER LOW OVER THE MID MISSISSIPPI VALLEY.
THIS LOW BECOMES BETTER ESTABLISHED ON SATURDAY OVER THE TENNESSEE
VALLEY...MOST IMPRESSIVE IN THE GFS AND WEAKER IN BOTH THE ECMWF AND
GEM. THE BASIC CONCEPT AND MAIN WEATHER DRIVERS ARE THE SAME FROM ALL
THE MODELS AS PLENTY OF ENERGY ROTATES THROUGH THE REGION DOWNSTREAM
OF A BURGEONING RIDGE THROUGH THE ROCKY MOUNTAIN STATES.
ACCORDINGLY...A BLENDED SOLUTION LOOKS REASONABLE THROUGH THE BULK
OF THE EXTENDED. THIS MID LEVEL LOW WILL GET SQUEEZED SOUTHEAST
THROUGH THE WEEKEND...BUT MANAGE TO MAINTAIN CYCLONIC FLOW OVER EAST
KENTUCKY UNTIL SUNDAY NIGHT WHEN IT WILL FINALLY MOVE OFF TO THE EAST
AS HEIGHTS RISE LOCALLY...IN RESPONSE TO A FLATTENING OF THE
FORMERLY ROBUST TROUGH TO THE WEST. A SMALL PORTION OF THIS RIDGE
THEN WILL SLIP THROUGH THE OHIO VALLEY ON MONDAY YIELDING THE HIGHEST
HEIGHTS OF THE LONG TERM PORTION OF THE FORECAST.
SENSIBLE WEATHER WILL FEATURE A CHILLY AND UNSETTLED TIME FRAME AT
LEAST INTO THE START OF THE WEEKEND. COLDER AIR WILL MOVE INTO THE
REGION ON NORTHWEST WINDS BEHIND THE DEEP SFC LOW SPINNING OFF TO
THE NORTHEAST EARLY IN THE PERIOD. THE LOW WILL MAINTAIN THE LOW
LEVEL MOISTURE OVER THE AREA WITH A COLD ENOUGH COLUMN OF AIR TO
SUPPORT SNOW FOR THE BULK OF THE TIME...THOUGH LIMITED DIURNAL RISES
WILL PROBABLY YIELD A MIX WITH RAIN EACH AFTERNOON. THE QPF WILL
ALSO BE RATHER LIMITED THROUGH THE FIRST PART OF THE WEEKEND ALSO
SERVING TO KEEP THE ACCUMULATIONS OF SNOW IN CHECK FOR MOST
LOCATIONS. WOULD ACTUALLY BE SURPRISED TO SEE MUCH IN THE WAY OF
ACCUMULATIONS DURING THE DAYTIME HOURS WITH A BETTER SHOT AT LIGHT
AMOUNTS STICKING EACH NIGHT. AMOUNTS WILL BE MAXIMIZED ON THE RIDGES
OF SOUTHEAST KENTUCKY WITH SOME OF THE PEAKS NEAR VIRGINIA LIKELY TO
HAVE MULTIPLE INCHES ON THE GROUND BY SUNDAY MORNING. THE REST OF THE
AREA WILL LIKELY SKATE BY WITH AN INCH OR LESS AND MAINLY JUST
SKIFFS OF VARYING THICKNESS. AS A RESULT...DO NOT FORESEE MUCH OF AN
IMPACT ON THE ROADS FOR THIS TIME PERIOD DESPITE THE CHILL AND
FREQUENT TIMES OF SNOW. THAT SAID...A FEW HEAVIER SNOW BURSTS OR
BANDS WILL BE POSSIBLY AND THAT COULD CAUSE BRIEF TRAVEL CHALLENGES
THROUGHOUT THE END OF THE WEEK AND INTO THE WEEKEND. DRIER AIR SHOULD
MOVE INTO THE REGION FROM THE NORTHWEST ON SUNDAY AND PUT AN END TO
MOST OF THE PCPN THREAT...BUT MAINTAIN THE BELOW NORMAL AIR MASS IN
PLACE. HIGH PRESSURE AND SOME SUNSHINE SHOULD RESULT IN DRY
CONDITIONS ALLOWING TEMPERATURES TO CREEP BACK UP CLOSER TO NORMAL
FOR MONDAY.
THE CR GRID LOAD CAME IN PRETTY GOOD GIVEN THE CONSENSUS PREFERENCE.
MADE ONLY MINOR CHANGES...MAINLY TO BEEF UP POPS IN THE SOUTHEAST
TERRAIN AND LIMIT THEM TO THE WEST. DID ALSO ADD SOME TERRAIN
DETAIL INTO THE LOWS BOTH SATURDAY AND SUNDAY NIGHTS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1230 PM EST TUE FEB 26 2013
DOWNSLOPING WINDS WILL CONTINUE THROUGH THE AFTERNOON...KEEPING
CEILINGS SOLIDLY VFR THROUGH THE AFTERNOON AND PERHAPS EVEN THROUGH A
GOOD CHUNK OF THE EVENING AT JKL AND LOZ...AT LEAST BASED ON CURRENT
OBSERVATIONS. SME WAS EXPERIENCING MVFR CIGS JUST BELOW 3K AS OF TAF
ISSUANCE...AND BASED ON UPSTREAM OBS...THIS TREND WILL CONTINUE THERE
FOR THE REMAINDER OF THE TAF PERIOD. THERE IS STILL AN OUTSIDE CHANCE
OF A THUNDERSTORM OR TWO POPPING UP IN EASTERN KENTUCKY THIS
AFTERNOON...BUT CONFIDENCE IS LOW THAT THIS WILL ACTUALLY OCCUR.
INSPITE OF THE LOW CONFIDENCE...VCTS GROUPS WERE USED IN ALL THREE
TAFS IN CASE A STRAY STORM IS ABLE TO FIRE UP THIS AFTERNOON NEAR ONE
OF THE TAF SITES. AS WINDS VEER AROUND TO THE SOUTHWEST LATE
TODAY...SOME LOWER CIGS MAY FINALLY MAKE THEIR WAY ACROSS THE
AREA...BUT SHOULD REMAIN MVFR WITH CIGS BETWEEN 2.5 AND 3K. STRONG
GUSTY WINDS WILL CONTINUE TODAY BEFORE SUBSIDING A BIT TONIGHT. AS
CEILINGS LOWER OVERNIGHT...SOME DRIZZLE AND ISOLATED LIGHT RAIN
SHOWERS WILL BE POSSIBLE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR KYZ087-088-118-
120.
&&
$$
UPDATE...AR
SHORT TERM...KAS
LONG TERM...GREIF
AVIATION...AR
AREA FORECAST DISCUSSION
NWS JACKSON KY
1127 AM EST TUE FEB 26 2013
.UPDATE...
ISSUED AT 1126 AM EST TUE FEB 26 2013
JUST A MINOR UPDATE WAS NECESSARY WITH THIS MORNINGS FORECAST.
SEVERAL AREAS OF CLEARING APPEARED EARLIER THIS MORNING IN THE
EXTENSIVE CLOUD SHIELD THAT HAS BEEN OVERSPREADING KENTUCKY SINCE
LATE LAST NIGHT. THE SKY COVER GRIDS WERE UPDATED TO TRACK THESE
AREAS OF CLEARING ACROSS THE FORECAST AREA AND INTO VIRGINIA AND WEST
VIRGINIA OVER THE NEXT SEVERAL HOURS. THE PRECIPITATION PROBABILITY
FORECAST WAS ALSO UPDATED TO REFLECT THE SCATTERED SHOWER ACTIVITY
THAT HAS PERSISTED THROUGHOUT THE MORNING. IT STILL APPEARS THAT MORE
NUMEROUS RAIN SHOWERS AND PERHAPS A THUNDERSTORM OR TWO WILL OCCUR
THROUGHOUT THE AFTERNOON...BEFORE THINGS TAPER OFF DURING THIS
EVENING. THE CORRESPONDING WEATHER TYPE AND QPF GRIDS WERE ALSO
REFORMULATED TO ACCOUNT FOR THE UPDATED PRECIPITATION PROBABILITY
FORECAST. ALSO REMOVED MORNING AND AFTERNOON WORDING FROM THE ZONE
FORECAST TEXT PRODUCT TO FRESHEN THINGS UP.
UPDATE ISSUED AT 652 AM EST TUE FEB 26 2013
DOWNSLOPING WINDS HAVE DEFINITELY TAKEN ITS TOLL ON THE RAIN AS IT
HAS PUSHED ACROSS THE AREA. MOST PLACES ARE GETTING LUCKY JUST TO
SQUEEZE OUT A HUNDREDTH OF AN INCH OF RAIN. THUS...HAVE DECIDED TO
TRIM POPS BACK...ESPECIALLY ACROSS THE SOUTH WHERE THINGS ARE ALREADY
STARTING TO DRY OUT. WITHIN THE NEXT FEW HOURS...ALL OF THE RAIN
SHOULD DEPART OFF TO THE NORTH...LEAVING BEHIND MAINLY DRY CONDITIONS
FOR THE BALANCE OF THE MORNING. HOWEVER...ANOTHER ROUND OF SHOWERS
STILL LOOKS ON TAP FOR THIS AFTERNOON...AS ANOTHER BAND OF SHOWERS
PUSHES EAST ACROSS THE AREA. THIS TIME THINGS MAY BE MORE CONVECTIVE
IN NATURE WITH THE THREAT OF STRONG WINDS AND SMALL HAIL STILL A
THREAT. LATEST HRRR DEFINITELY SUPPORTS SOME STRONG
SHOWERS/THUNDERSTORMS DEVELOPING BY EARLY AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 320 AM EST TUE FEB 26 2013
UPPER LEVEL LOW WILL CONTINUE TO PUSH INTO THE OHIO RIVER VALLEY
TODAY WITH AN OCCLUDING FRONTAL BOUNDARY CONTINUING TO LIFT NORTH
ACROSS THE AREA THIS MORNING. A BAND OF RAIN SHOWERS WILL PUSH NORTH
THROUGH THE EARLY MORNING HOURS. DOWNSLOPING SOUTHEAST WINDS WILL
CONTINUE TO TRY TO EAT AWAY AT THIS RAIN AS IT MOVES ACROSS THE AREA.
THIS WILL KEEP OVERALL RAINFALL AMOUNTS ON THE LIGHT SIDE...BUT WE
SHOULD SEE JUST ABOUT EVERYONE MEASURE BY 13Z. THIS BAND WILL QUICKLY
DEPART TO THE NORTH SHORTLY AFTER DAYBREAK...WITH ONLY SOME ISOLATED
TO SCATTERED SHOWERS LINGERING NEAR THE I-75 CORRIDOR. DOWNSLOPING
WINDS WILL LIKELY KEEP MOST OF THE ACTIVITY CLOSER TO CENTRAL
KENTUCKY. EVENTUALLY WINDS WILL VEER AROUND TO THE SOUTH OR SOUTHWEST
THIS AFTERNOON AS ANOTHER IMPULSE RIDES NORTHEAST ACROSS THE AREA.
THIS WILL TRIGGER ANOTHER ROUND OF SCATTERED TO NUMEROUS SHOWERS. IN
ADDITION...INSTABILITY REMAINS QUITE IMPRESSIVE...SO CANNOT RULE OUT
SOME ISOLATED THUNDERSTORMS WITH PERHAPS SOME SMALL HAIL. FINALLY A
THIRD WAVE WILL RIDE NORTHEAST ACROSS THE AREA THIS
EVENING...GENERATING SOME MORE SCATTERED SHOWERS. BY THIS
EVENING...INSTABILITY WILL DEPART TO THE NORTH...SO NO THUNDER
THROUGH THE EVENING HOURS. AS WINDS VEER TO THE SOUTHWEST
TONIGHT...LOWER CIGS MAY OVERSPREAD THE AREA...POSSIBLY LEADING TO
SOME PATCHY DRIZZLE LATE TONIGHT. HOWEVER...UNCERTAINTY EXISTS WITH
HOW MUCH LOW LEVEL MOISTURE WILL DEVELOP WHICH WOULD BE NEEDED TO
ACHIEVE ANY DRIZZLE. FINALLY...AS THE UPPER LEVEL LOW CONTINUES TO
ROTATE EASTWARD ACROSS THE OHIO RIVER VALLEY ON WEDNESDAY...THIS
SYSTEM WILL SEND A VIGOROUS SHORTWAVE SOUTHEAST ACROSS THE
AREA...GIVING WAY TO ANOTHER ROUND OF RAIN. COLDER AIR WILL ALSO
SETTLE SOUTHWARD AND AS WE WETBULB THROUGH THE EVENING...WE SHOULD
SEE SOME SNOW STARTING TO MIX IN AS WE HEAD INTO THE EVENING HOURS.
AS FOR THE WIND ADVISORY...GOING TO LEAVE THE COUNTIES NEAR THE
VIRGINIA BORDER IN THE ADVISORY. THE MESONET STATION AT DORTON IS HAS
GUSTED UP TO 38 MPH AND THIS SHOULD ONLY GO HIGHER AS THE SYSTEM
MOVES TOWARDS US TODAY.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 350 AM EST TUE FEB 26 2013
THE MODELS ARE IN RELATIVELY GOOD AGREEMENT ALOFT THROUGH THE FIRST
PART OF THE EXTENDED...ESPECIALLY CONSIDERING THE AMPLIFIED NATURE OF
THE PATTERN. A DEEP AND LARGE CLOSED LOW WILL SLOWLY ROLL OUT OF THE
OHIO VALLEY ON THURSDAY WITH THE GFS RUNNING SLIGHTLY FASTER THAN THE
ECMWF. IN THE WAKE OF THIS...A STEADY STREAM OF UNCONSOLIDATED ENERGY
WILL SLIP THROUGH THE REGION INTO FRIDAY WHILE THE WESTERN EXTENT OF
IT STARTS TO CARVE OUT ANOTHER LOW OVER THE MID MISSISSIPPI VALLEY.
THIS LOW BECOMES BETTER ESTABLISHED ON SATURDAY OVER THE TENNESSEE
VALLEY...MOST IMPRESSIVE IN THE GFS AND WEAKER IN BOTH THE ECMWF AND
GEM. THE BASIC CONCEPT AND MAIN WEATHER DRIVERS ARE THE SAME FROM ALL
THE MODELS AS PLENTY OF ENERGY ROTATES THROUGH THE REGION DOWNSTREAM
OF A BURGEONING RIDGE THROUGH THE ROCKY MOUNTAIN STATES.
ACCORDINGLY...A BLENDED SOLUTION LOOKS REASONABLE THROUGH THE BULK
OF THE EXTENDED. THIS MID LEVEL LOW WILL GET SQUEEZED SOUTHEAST
THROUGH THE WEEKEND...BUT MANAGE TO MAINTAIN CYCLONIC FLOW OVER EAST
KENTUCKY UNTIL SUNDAY NIGHT WHEN IT WILL FINALLY MOVE OFF TO THE EAST
AS HEIGHTS RISE LOCALLY...IN RESPONSE TO A FLATTENING OF THE
FORMERLY ROBUST TROUGH TO THE WEST. A SMALL PORTION OF THIS RIDGE
THEN WILL SLIP THROUGH THE OHIO VALLEY ON MONDAY YIELDING THE HIGHEST
HEIGHTS OF THE LONG TERM PORTION OF THE FORECAST.
SENSIBLE WEATHER WILL FEATURE A CHILLY AND UNSETTLED TIME FRAME AT
LEAST INTO THE START OF THE WEEKEND. COLDER AIR WILL MOVE INTO THE
REGION ON NORTHWEST WINDS BEHIND THE DEEP SFC LOW SPINNING OFF TO
THE NORTHEAST EARLY IN THE PERIOD. THE LOW WILL MAINTAIN THE LOW
LEVEL MOISTURE OVER THE AREA WITH A COLD ENOUGH COLUMN OF AIR TO
SUPPORT SNOW FOR THE BULK OF THE TIME...THOUGH LIMITED DIURNAL RISES
WILL PROBABLY YIELD A MIX WITH RAIN EACH AFTERNOON. THE QPF WILL
ALSO BE RATHER LIMITED THROUGH THE FIRST PART OF THE WEEKEND ALSO
SERVING TO KEEP THE ACCUMULATIONS OF SNOW IN CHECK FOR MOST
LOCATIONS. WOULD ACTUALLY BE SURPRISED TO SEE MUCH IN THE WAY OF
ACCUMULATIONS DURING THE DAYTIME HOURS WITH A BETTER SHOT AT LIGHT
AMOUNTS STICKING EACH NIGHT. AMOUNTS WILL BE MAXIMIZED ON THE RIDGES
OF SOUTHEAST KENTUCKY WITH SOME OF THE PEAKS NEAR VIRGINIA LIKELY TO
HAVE MULTIPLE INCHES ON THE GROUND BY SUNDAY MORNING. THE REST OF THE
AREA WILL LIKELY SKATE BY WITH AN INCH OR LESS AND MAINLY JUST
SKIFFS OF VARYING THICKNESS. AS A RESULT...DO NOT FORESEE MUCH OF AN
IMPACT ON THE ROADS FOR THIS TIME PERIOD DESPITE THE CHILL AND
FREQUENT TIMES OF SNOW. THAT SAID...A FEW HEAVIER SNOW BURSTS OR
BANDS WILL BE POSSIBLY AND THAT COULD CAUSE BRIEF TRAVEL CHALLENGES
THROUGHOUT THE END OF THE WEEK AND INTO THE WEEKEND. DRIER AIR SHOULD
MOVE INTO THE REGION FROM THE NORTHWEST ON SUNDAY AND PUT AN END TO
MOST OF THE PCPN THREAT...BUT MAINTAIN THE BELOW NORMAL AIR MASS IN
PLACE. HIGH PRESSURE AND SOME SUNSHINE SHOULD RESULT IN DRY
CONDITIONS ALLOWING TEMPERATURES TO CREEP BACK UP CLOSER TO NORMAL
FOR MONDAY.
THE CR GRID LOAD CAME IN PRETTY GOOD GIVEN THE CONSENSUS PREFERENCE.
MADE ONLY MINOR CHANGES...MAINLY TO BEEF UP POPS IN THE SOUTHEAST
TERRAIN AND LIMIT THEM TO THE WEST. DID ALSO ADD SOME TERRAIN
DETAIL INTO THE LOWS BOTH SATURDAY AND SUNDAY NIGHTS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 652 AM EST TUE FEB 26 2013
DOWNSLOPING WINDS WILL CONTINUE INTO THE AFTERNOON...KEEPING CEILINGS
SOLIDLY VFR THROUGH THE AFTERNOON AND PERHAPS EVEN THROUGH A GOOD
CHUNK OF THE EVENING. AS WINDS VEER AROUND TO THE SOUTHWEST LATE
TODAY...SOME LOWER CIGS MAY FINALLY WORK THEIR WAY ACROSS THE
AREA...BUT SHOULD REMAIN MVFR. STRONG GUSTY WINDS WILL CONTINUE TODAY
BEFORE SUBSIDING A BIT TONIGHT. AS CEILINGS LOWER TONIGHT...SOME
DRIZZLE MAY BE POSSIBLE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR KYZ087-088-118-
120.
&&
$$
UPDATE...AR
SHORT TERM...KAS
LONG TERM...GREIF
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS JACKSON KY
652 AM EST TUE FEB 26 2013
.UPDATE...
ISSUED AT 652 AM EST TUE FEB 26 2013
DOWNSLOPING WINDS HAVE DEFINITELY TAKEN ITS TOLL ON THE RAIN AS IT
HAS PUSHED ACROSS THE AREA. MOST PLACES ARE GETTING LUCKY JUST TO
SQUEEZE OUT A HUNDREDTH OF AN INCH OF RAIN. THUS...HAVE DECIDED TO
TRIM POPS BACK...ESPECIALLY ACROSS THE SOUTH WHERE THINGS ARE ALREADY
STARTING TO DRY OUT. WITHIN THE NEXT FEW HOURS...ALL OF THE RAIN
SHOULD DEPART OFF TO THE NORTH...LEAVING BEHIND MAINLY DRY CONDITIONS
FOR THE BALANCE OF THE MORNING. HOWEVER...ANOTHER ROUND OF SHOWERS
STILL LOOKS ON TAP FOR THIS AFTERNOON...AS ANOTHER BAND OF SHOWERS
PUSHES EAST ACROSS THE AREA. THIS TIME THINGS MAY BE MORE CONVECTIVE
IN NATURE WITH THE THREAT OF STRONG WINDS AND SMALL HAIL STILL A
THREAT. LATEST HRRR DEFINITELY SUPPORTS SOME STRONG
SHOWERS/THUNDERSTORMS DEVELOPING BY EARLY AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 320 AM EST TUE FEB 26 2013
UPPER LEVEL LOW WILL CONTINUE TO PUSH INTO THE OHIO RIVER VALLEY
TODAY WITH AN OCCLUDING FRONTAL BOUNDARY CONTINUING TO LIFT NORTH
ACROSS THE AREA THIS MORNING. A BAND OF RAIN SHOWERS WILL PUSH NORTH
THROUGH THE EARLY MORNING HOURS. DOWNSLOPING SOUTHEAST WINDS WILL
CONTINUE TO TRY TO EAT AWAY AT THIS RAIN AS IT MOVES ACROSS THE AREA.
THIS WILL KEEP OVERALL RAINFALL AMOUNTS ON THE LIGHT SIDE...BUT WE
SHOULD SEE JUST ABOUT EVERYONE MEASURE BY 13Z. THIS BAND WILL QUICKLY
DEPART TO THE NORTH SHORTLY AFTER DAYBREAK...WITH ONLY SOME ISOLATED
TO SCATTERED SHOWERS LINGERING NEAR THE I-75 CORRIDOR. DOWNSLOPING
WINDS WILL LIKELY KEEP MOST OF THE ACTIVITY CLOSER TO CENTRAL
KENTUCKY. EVENTUALLY WINDS WILL VEER AROUND TO THE SOUTH OR SOUTHWEST
THIS AFTERNOON AS ANOTHER IMPULSE RIDES NORTHEAST ACROSS THE AREA.
THIS WILL TRIGGER ANOTHER ROUND OF SCATTERED TO NUMEROUS SHOWERS. IN
ADDITION...INSTABILITY REMAINS QUITE IMPRESSIVE...SO CANNOT RULE OUT
SOME ISOLATED THUNDERSTORMS WITH PERHAPS SOME SMALL HAIL. FINALLY A
THIRD WAVE WILL RIDE NORTHEAST ACROSS THE AREA THIS
EVENING...GENERATING SOME MORE SCATTERED SHOWERS. BY THIS
EVENING...INSTABILITY WILL DEPART TO THE NORTH...SO NO THUNDER
THROUGH THE EVENING HOURS. AS WINDS VEER TO THE SOUTHWEST
TONIGHT...LOWER CIGS MAY OVERSPREAD THE AREA...POSSIBLY LEADING TO
SOME PATCHY DRIZZLE LATE TONIGHT. HOWEVER...UNCERTAINTY EXISTS WITH
HOW MUCH LOW LEVEL MOISTURE WILL DEVELOP WHICH WOULD BE NEEDED TO
ACHIEVE ANY DRIZZLE. FINALLY...AS THE UPPER LEVEL LOW CONTINUES TO
ROTATE EASTWARD ACROSS THE OHIO RIVER VALLEY ON WEDNESDAY...THIS
SYSTEM WILL SEND A VIGOROUS SHORTWAVE SOUTHEAST ACROSS THE
AREA...GIVING WAY TO ANOTHER ROUND OF RAIN. COLDER AIR WILL ALSO
SETTLE SOUTHWARD AND AS WE WETBULB THROUGH THE EVENING...WE SHOULD
SEE SOME SNOW STARTING TO MIX IN AS WE HEAD INTO THE EVENING HOURS.
AS FOR THE WIND ADVISORY...GOING TO LEAVE THE COUNTIES NEAR THE
VIRGINIA BORDER IN THE ADVISORY. THE MESONET STATION AT DORTON IS HAS
GUSTED UP TO 38 MPH AND THIS SHOULD ONLY GO HIGHER AS THE SYSTEM
MOVES TOWARDS US TODAY.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 350 AM EST TUE FEB 26 2013
THE MODELS ARE IN RELATIVELY GOOD AGREEMENT ALOFT THROUGH THE FIRST
PART OF THE EXTENDED...ESPECIALLY CONSIDERING THE AMPLIFIED NATURE OF
THE PATTERN. A DEEP AND LARGE CLOSED LOW WILL SLOWLY ROLL OUT OF THE
OHIO VALLEY ON THURSDAY WITH THE GFS RUNNING SLIGHTLY FASTER THAN THE
ECMWF. IN THE WAKE OF THIS...A STEADY STREAM OF UNCONSOLIDATED ENERGY
WILL SLIP THROUGH THE REGION INTO FRIDAY WHILE THE WESTERN EXTENT OF
IT STARTS TO CARVE OUT ANOTHER LOW OVER THE MID MISSISSIPPI VALLEY.
THIS LOW BECOMES BETTER ESTABLISHED ON SATURDAY OVER THE TENNESSEE
VALLEY...MOST IMPRESSIVE IN THE GFS AND WEAKER IN BOTH THE ECMWF AND
GEM. THE BASIC CONCEPT AND MAIN WEATHER DRIVERS ARE THE SAME FROM ALL
THE MODELS AS PLENTY OF ENERGY ROTATES THROUGH THE REGION DOWNSTREAM
OF A BURGEONING RIDGE THROUGH THE ROCKY MOUNTAIN STATES.
ACCORDINGLY...A BLENDED SOLUTION LOOKS REASONABLE THROUGH THE BULK
OF THE EXTENDED. THIS MID LEVEL LOW WILL GET SQUEEZED SOUTHEAST
THROUGH THE WEEKEND...BUT MANAGE TO MAINTAIN CYCLONIC FLOW OVER EAST
KENTUCKY UNTIL SUNDAY NIGHT WHEN IT WILL FINALLY MOVE OFF TO THE EAST
AS HEIGHTS RISE LOCALLY...IN RESPONSE TO A FLATTENING OF THE
FORMERLY ROBUST TROUGH TO THE WEST. A SMALL PORTION OF THIS RIDGE
THEN WILL SLIP THROUGH THE OHIO VALLEY ON MONDAY YIELDING THE HIGHEST
HEIGHTS OF THE LONG TERM PORTION OF THE FORECAST.
SENSIBLE WEATHER WILL FEATURE A CHILLY AND UNSETTLED TIME FRAME AT
LEAST INTO THE START OF THE WEEKEND. COLDER AIR WILL MOVE INTO THE
REGION ON NORTHWEST WINDS BEHIND THE DEEP SFC LOW SPINNING OFF TO
THE NORTHEAST EARLY IN THE PERIOD. THE LOW WILL MAINTAIN THE LOW
LEVEL MOISTURE OVER THE AREA WITH A COLD ENOUGH COLUMN OF AIR TO
SUPPORT SNOW FOR THE BULK OF THE TIME...THOUGH LIMITED DIURNAL RISES
WILL PROBABLY YIELD A MIX WITH RAIN EACH AFTERNOON. THE QPF WILL
ALSO BE RATHER LIMITED THROUGH THE FIRST PART OF THE WEEKEND ALSO
SERVING TO KEEP THE ACCUMULATIONS OF SNOW IN CHECK FOR MOST
LOCATIONS. WOULD ACTUALLY BE SURPRISED TO SEE MUCH IN THE WAY OF
ACCUMULATIONS DURING THE DAYTIME HOURS WITH A BETTER SHOT AT LIGHT
AMOUNTS STICKING EACH NIGHT. AMOUNTS WILL BE MAXIMIZED ON THE RIDGES
OF SOUTHEAST KENTUCKY WITH SOME OF THE PEAKS NEAR VIRGINIA LIKELY TO
HAVE MULTIPLE INCHES ON THE GROUND BY SUNDAY MORNING. THE REST OF THE
AREA WILL LIKELY SKATE BY WITH AN INCH OR LESS AND MAINLY JUST
SKIFFS OF VARYING THICKNESS. AS A RESULT...DO NOT FORESEE MUCH OF AN
IMPACT ON THE ROADS FOR THIS TIME PERIOD DESPITE THE CHILL AND
FREQUENT TIMES OF SNOW. THAT SAID...A FEW HEAVIER SNOW BURSTS OR
BANDS WILL BE POSSIBLY AND THAT COULD CAUSE BRIEF TRAVEL CHALLENGES
THROUGHOUT THE END OF THE WEEK AND INTO THE WEEKEND. DRIER AIR SHOULD
MOVE INTO THE REGION FROM THE NORTHWEST ON SUNDAY AND PUT AN END TO
MOST OF THE PCPN THREAT...BUT MAINTAIN THE BELOW NORMAL AIR MASS IN
PLACE. HIGH PRESSURE AND SOME SUNSHINE SHOULD RESULT IN DRY
CONDITIONS ALLOWING TEMPERATURES TO CREEP BACK UP CLOSER TO NORMAL
FOR MONDAY.
THE CR GRID LOAD CAME IN PRETTY GOOD GIVEN THE CONSENSUS PREFERENCE.
MADE ONLY MINOR CHANGES...MAINLY TO BEEF UP POPS IN THE SOUTHEAST
TERRAIN AND LIMIT THEM TO THE WEST. DID ALSO ADD SOME TERRAIN
DETAIL INTO THE LOWS BOTH SATURDAY AND SUNDAY NIGHTS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 652 AM EST TUE FEB 26 2013
DOWNSLOPING WINDS WILL CONTINUE INTO THE AFTERNOON...KEEPING CEILINGS
SOLIDLY VFR THROUGH THE AFTERNOON AND PERHAPS EVEN THROUGH A GOOD
CHUNK OF THE EVENING. AS WINDS VEER AROUND TO THE SOUTHWEST LATE
TODAY...SOME LOWER CIGS MAY FINALLY WORK THEIR WAY ACROSS THE
AREA...BUT SHOULD REMAIN MVFR. STRONG GUSTY WINDS WILL CONTINUE TODAY
BEFORE SUBSIDING A BIT TONIGHT. AS CEILINGS LOWER TONIGHT...SOME
DRIZZLE MAY BE POSSIBLE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR KYZ087-088-118-
120.
&&
$$
UPDATE...KAS
SHORT TERM...KAS
LONG TERM...GREIF
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
848 PM EST WED FEB 27 2013
.SYNOPSIS...
AN UPPER LEVEL LOW WILL MOVE ACROSS THE AREA OVERNIGHT AND PUSH
INTO THE NORTHEAST FOR THE END OF THE WEEK. AS THE LOW SHIFTS EAST
OF THE REGION...COLDER AIR WILL FILTER INTO THE AREA TONIGHT AND
ALLOW FOR A MIX OF RAIN AND SNOW SHOWERS TO CHANGE OVER TO MOSTLY
SNOW SHOWERS INTO FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
WITH 845PM UPDATE...HAVE LOWERED TEMPERATURES BY 1-2 DEGREES BASED
ON CURRENT OBSERVATIONS. THIS SHOULD ALLOW FOR PRECIPITATION TO
TRANSITION TO SNOW SLIGHTLY EARLIER THAN ORIGINALLY FORECAST. AT
THIS POINT...NO AUTOMATED STATIONS HAVE REPORTED A
CHANGEOVER...ALTHOUGH NEW CASTLE HAS REPORTED UNKNOWN
PRECIPITATION. HOWEVER...HAVE SEEN A FEW REPORTS THROUGH THE PING
PROGRAM AS WELL AS RELAYED INFORMATION THROUGH BROADCAST MEDIA
THAT SOME PLACES ARE ALREADY RECEIVING SNOW. PREVIOUS DISCUSSION
FOLLOWS.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A RATHER ELONGATED
CLOSED UPPER LOW THAT STRETCHES ACROSS THE SOUTHERN GREAT LAKES
AND OHIO VALLEY. AT THE SURFACE...A 999MB LOW IS CENTERED ACROSS
SOUTHERN MICHIGAN WITH ANOTHER LOW DEVELOPING AS IT MOVES
NORTHWARD ACROSS NEW JERSEY. THE LOW IN MICHIGAN IS DRIVING A
SOUTHWESTERLY FLOW ACROSS THE AREA TODAY. SOUNDINGS INDICATE A
SFC-900MB MELTING LAYER STRONG ENOUGH TO ALLOW FOR PRECIP SOUTH
AND WEST OF PITTSBURGH TO BE ALL RAIN. 1000-700MB 2840M THICKNESS
LINE ALSO SEEMS TO COINCIDE FAIRLY WELL WITH RAIN/SNOW LINE
NORTHEAST OF PITTSBURGH.
THIS EVENING...THE BROAD UPPER LOW WILL SLOWLY MEANDER EASTWARD
ACROSS THE OHIO VALLEY...WITH THE NEXT VORT LOBE SWINGING AROUND
ITS BASE. WRF-ARW 1KM SIMULATED REFLECTIVITY DEPICTS MORE
CONVECTIVE SHOWERS EARLY THIS EVENING...SO HAVE GONE WITH
ISOLATED/SCATTERED INCREASING TO MORE NUMEROUS AS THE UPPER LOW
APPROACHES FROM THE WEST. DESPITE COLDER AIR ADVECTING IN WITH
THE COLD POOL ALOFT AND ASSOCIATED UPPER LOW...GFS/NAM SOUNDINGS
CONTINUE TO INDICATE PRECIPITATION WILL FALL INITIALLY AS RAIN
WITH A SUFFICIENT SFC-900MB MELTING LAYER REMAINING IN PLACE.
THUS...FORECAST BEINGS WITH MOSTLY RAIN...EXCEPT FOR SOME RAIN-SNOW
CLOSER TO 1000-700MB CRITICAL THICKNESS ACROSS THE NORTH AND WITH
THE LACK OF A PRONOUNCED MELTING LAYER ACROSS THE RIDGES.
OVERNIGHT...GFS/NAM AGREE THAT THE UPPER LOW WILL CROSS THE AREA AS
IT SHIFTS FROM WESTERN OHIO INTO WESTERN NY. WEAK CAA AND COOLING
SFC-900MB LAYER WILL ALLOW FOR ENTIRE COLUMN TO DROP BELOW
FREEZING AND PRECIPITATION TO CHANGE OVER TO ALL SNOW SHOWERS
TONIGHT. ACCUMULATIONS WILL BE AN INCH OR LESS FOR SOUTHWEST
PA...EASTERN OHIO...AND NORTHERN WV WITH 1 TO 2 INCHES POSSIBLE
TONIGHT ACROSS THE ALLEGHENY FRONT/LAUREL HIGHLANDS AND I-80
CORRIDOR. TEMPS TONIGHT ARE FAIRLY CLOSE TO A MAV/MET BLEND...WITH
LOWS RANGING FROM THE MID 20S ACROSS THE EASTERN RIDGES TO THE
LOWER 30S ELSEWHERE.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
A MODEL CONSENSUS INDICATES THAT THE UPPER LOW WILL SLOWLY MEANDER
EASTWARD INTO NEW ENGLAND THURSDAY AND FRIDAY...LEAVING THE UPPER
OHIO VALLEY IN A MOIST...NORTHWESTERLY FLOW OFF OF THE GREAT
LAKES.
THE LOW-LEVEL FLOW WILL BE CLOSE TO ZONAL MUCH OF THE DAY THURSDAY
AS A SERIES OF VORT LOBES ROTATES AROUND THE UPPER LOW AND INTO
THE AREA. WITH SFC TEMPS WARMING TO THE MID TO UPPER 30S ACROSS
THE LOWLANDS...ANTICIPATE LITTLE ACCUMULATION DURING DAYLIGHT
HOURS ACROSS THE LOWLANDS. WITH SOME UPSLOPING AND TEMPS IN THE
LOWER 30S...1 TO 2 INCHES WILL BE POSSIBLE ACROSS THE HIGHER
ELEVATIONS.
VORT ENERGY WILL SLIDE EAST OF THE UPPER OHIO VALLEY THURSDAY
NIGHT INTO FRIDAY. DURING THIS TIME...THE LOW-LEVEL FLOW WILL
VEER TO MORE NORTH-NORTHWESTERLY...ALLOWING FOR A MOISTURE FETCH
OFF OF LAKE HURON WITH MOISTURE LACKING FROM A PARTIALLY FROZEN
LAKE ERIE. ONE LIMITING FACTOR DESPITE THE NNWRLY FLOW WILL BE
THAT THE AIR MASS WILL NOT BE QUITE COLD ENOUGH TO SUPPORT LAKE
EFFECT. THUS...ANTICIPATE LITTLE MORE THAN SCATTERED SNOW SHOWERS
THROUGH THIS PERIOD WITH AROUND AN INCH FOR THE LOWLANDS AND AN
ADDITIONAL 1 TO 2 FOR THE RIDGES. TEMPS THROUGH THIS PERIOD WILL
BE AROUND 5 DEGREES BELOW NORMAL WITH THE NORTHERLY COMPONENT
CONTINUING TO PULL COOLER...CANADIAN AIR INTO THE AREA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
ECMWF AND GFS INDICATE CONTD MAINTENANCE OF THE ERN NORTH
AMERICAN TROF VIA SHRTWV ENERGY THRU THE LONG TERM PD. THE
EXTENDED FORECAST THUS CONTINUES TO FEATURE SUB AVERAGE TEMPS AND
NR CLIMO/CHC POPS UNTIL THE TROF AXIS SHIFT SUFFICIENTLY
EWD...PROBABLY BY SATURDAY.
SHRTWV RIDGE IN ADVN OF MIDWRN LOW IS CURRENTLY PROGGED TO
SUPPRESS PRECIP PROBABILITIES...UNTIL THE LOW INITIATES PCPN LTR
ON TUE. CONFIDENCE IN THAT PORTION OF THE FORECAST IS MINIMAL
GIVEN PROJECTIONS OF A CUTOFF SYSTEM WITH QUESTIONS OF MAGNITUDE
AND PLACEMENT OF THE LOW CENTERS.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
SFC/UPR LOWS DRIFTG EWD ACRS THE GT LKS WL CONT TO BRING MVFR
CONDS WITH A MIX OF SHRA/SHSN THIS EVE...CHG TO ALL SHSN TNGT. MAY
SEE A BREAK IN THE PCPN OVRNGT...BUT ANOTHER WV IS EXPD TO BRING
ADDNL MVFR SHSN THU.
.OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/...
MAINLY CIGS RESTRICTIONS ARE LIKLEY INTO SUNDAY AS LOW PRES CONTS
TO DRIFT EWD. VFR CONDS EXPD TO RETURN MON AS HI PRES BLDS IN.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
642 PM EST WED FEB 27 2013
.SYNOPSIS...
AN UPPER LEVEL LOW WILL MOVE ACROSS THE AREA OVERNIGHT AND PUSH
INTO THE NORTHEAST FOR THE END OF THE WEEK. AS THE LOW SHIFTS EAST
OF THE REGION...COLDER AIR WILL FILTER INTO THE AREA TONIGHT AND
ALLOW FOR A MIX OF RAIN AND SNOW SHOWERS TO CHANGE OVER TO MOSTLY
SNOW SHOWERS INTO FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
WITH 630PM UPDATE...ONLY MINOR CHANGES WERE MADE TO FORECAST. 00Z
RAOB SHOWS THAT THE MELTING LAYER IS ONLY ABOUT 1500 FEET ABOVE
GROUND LEVEL...AND AS TEMPERATURES CONTINUE TO DROP OFF THIS
EVENING...PRECIPITATION WILL BEGIN TO MIX THEN TURN OVER TO SNOW.
MADE SLIGHT ADJUSTMENTS TO TIMING OF PRECIPITATION...BUT NO
CHANGES TO QPF OR SNOW ACCUMULATION. PREVIOUS DISCUSSION FOLLOWS.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A RATHER ELONGATED
CLOSED UPPER LOW THAT STRETCHES ACROSS THE SOUTHERN GREAT LAKES
AND OHIO VALLEY. AT THE SURFACE...A 999MB LOW IS CENTERED ACROSS
SOUTHERN MICHIGAN WITH ANOTHER LOW DEVELOPING AS IT MOVES
NORTHWARD ACROSS NEW JERSEY. THE LOW IN MICHIGAN IS DRIVING A
SOUTHWESTERLY FLOW ACROSS THE AREA THIS TODAY. SOUNDINGS INDICATE A
SFC-900MB MELTING LAYER STRONG ENOUGH TO ALLOW FOR PRECIP SOUTH
AND WEST OF PITTSBURGH TO BE ALL RAIN. 1000-700MB 2840M THICKNESS
LINE ALSO SEEMS TO COINCIDE FAIRLY WELL WITH RAIN/SNOW LINE
NORTHEAST OF PITTSBURGH.
THIS EVENING...THE BROAD UPPER LOW WILL SLOWLY MEANDER EASTWARD
ACROSS THE OHIO VALLEY...WITH THE NEXT VORT LOBE SWINGING AROUND
ITS BASE. WRF-ARW 1KM SIMULATED REFLECTIVITY DEPICTS MORE
CONVECTIVE SHOWERS EARLY THIS EVENING...SO HAVE GONE WITH
ISOLATED/SCATTERED INCREASING TO MORE NUMEROUS AS THE UPPER LOW
APPROACHES FROM THE WEST. DESPITE COLDER AIR ADVECTING IN WITH
THE COLD POOL ALOFT AND ASSOCIATED UPPER LOW...GFS/NAM SOUNDINGS
CONTINUE TO INDICATE PRECIPITATION WILL FALL INITIALLY AS RAIN
WITH A SUFFICIENT SFC-900MB MELTING LAYER REMAINING IN PLACE.
THUS...FORECAST BEINGS WITH MOSTLY RAIN...EXCEPT FOR SOME RAIN-SNOW
CLOSER TO 1000-700MB CRITICAL THICKNESS ACROSS THE NORTH AND WITH
THE LACK OF A PRONOUNCED MELTING LAYER ACROSS THE RIDGES.
OVERNIGHT...GFS/NAM AGREE THAT THE UPPER LOW WILL CROSS THE AREA AS
IT SHIFTS FROM WESTERN OHIO INTO WESTERN NY. WEAK CAA AND COOLING
SFC-900MB LAYER WILL ALLOW FOR ENTIRE COLUMN TO DROP BELOW
FREEZING AND PRECIPITATION TO CHANGE OVER TO ALL SNOW SHOWERS
TONIGHT. ACCUMULATIONS WILL BE AN INCH OR LESS FOR SOUTHWEST
PA...EASTERN OHIO...AND NORTHERN WV WITH 1 TO 2 INCHES POSSIBLE
TONIGHT ACROSS THE ALLEGHENY FRONT/LAUREL HIGHLANDS AND I-80
CORRIDOR. TEMPS TONIGHT ARE FAIRLY CLOSE TO A MAV/MET BLEND...WITH
LOWS RANGING FROM THE MID 20S ACROSS THE EASTERN RIDGES TO THE
LOWER 30S ELSEWHERE.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
A MODEL CONSENSUS INDICATES THAT THE UPPER LOW WILL SLOWLY MEANDER
EASTWARD INTO NEW ENGLAND THURSDAY AND FRIDAY...LEAVING THE UPPER
OHIO VALLEY IN A MOIST...NORTHWESTERLY FLOW OFF OF THE GREAT
LAKES.
THE LOW-LEVEL FLOW WILL BE CLOSE TO ZONAL MUCH OF THE DAY THURSDAY
AS A SERIES OF VORT LOBES ROTATES AROUND THE UPPER LOW AND INTO
THE AREA. WITH SFC TEMPS WARMING TO THE MID TO UPPER 30S ACROSS
THE LOWLANDS...ANTICIPATE LITTLE ACCUMULATION DURING DAYLIGHT
HOURS ACROSS THE LOWLANDS. WITH SOME UPSLOPING AND TEMPS IN THE
LOWER 30S...1 TO 2 INCHES WILL BE POSSIBLE ACROSS THE HIGHER
ELEVATIONS.
VORT ENERGY WILL SLIDE EAST OF THE UPPER OHIO VALLEY THURSDAY
NIGHT INTO FRIDAY. DURING THIS TIME...THE LOW-LEVEL FLOW WILL
VEER TO MORE NORTH-NORTHWESTERLY...ALLOWING FOR A MOISTURE FETCH
OFF OF LAKE HURON WITH MOISTURE LACKING FROM A PARTIALLY FROZEN
LAKE ERIE. ONE LIMITING FACTOR DESPITE THE NNWRLY FLOW WILL BE
THAT THE AIR MASS WILL NOT BE QUITE COLD ENOUGH TO SUPPORT LAKE
EFFECT. THUS...ANTICIPATE LITTLE MORE THAN SCATTERED SNOW SHOWERS
THROUGH THIS PERIOD WITH AROUND AN INCH FOR THE LOWLANDS AND AN
ADDITIONAL 1 TO 2 FOR THE RIDGES. TEMPS THROUGH THIS PERIOD WILL
BE AROUND 5 DEGREES BELOW NORMAL WITH THE NORTHERLY COMPONENT
CONTINUING TO PULL COOLER...CANADIAN AIR INTO THE AREA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
ECMWF AND GFS INDICATE CONTD MAINTENANCE OF THE ERN NORTH
AMERICAN TROF VIA SHRTWV ENERGY THRU THE LONG TERM PD. THE
EXTENDED FORECAST THUS CONTINUES TO FEATURE SUB AVERAGE TEMPS AND
NR CLIMO/CHC POPS UNTIL THE TROF AXIS SHIFT SUFFICIENTLY
EWD...PROBABLY BY SATURDAY.
SHRTWV RIDGE IN ADVN OF MIDWRN LOW IS CURRENTLY PROGGED TO
SUPPRESS PRECIP PROBABILITIES...UNTIL THE LOW INITIATES PCPN LTR
ON TUE. CONFIDENCE IN THAT PORTION OF THE FORECAST IS MINIMAL
GIVEN PROJECTIONS OF A CUTOFF SYSTEM WITH QUESTIONS OF MAGNITUDE
AND PLACEMENT OF THE LOW CENTERS.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
SFC/UPR LOWS DRIFTG EWD ACRS THE GT LKS WL CONT TO BRING MVFR
CONDS WITH A MIX OF SHRA/SHSN THIS EVE...CHG TO ALL SHSN TNGT. MAY
SEE A BREAK IN THE PCPN OVRNGT...BUT ANOTHER WV IS EXPD TO BRING
ADDNL MVFR SHSN THU.
.OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/...
MAINLY CIGS RESTRICTIONS ARE LIKLEY INTO SUNDAY AS LOW PRES CONTS
TO DRIFT EWD. VFR CONDS EXPD TO RETURN MON AS HI PRES BLDS IN.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1023 AM EST TUE FEB 26 2013
.SYNOPSIS...
STRONG LOW PRESSURE WILL TRACK FROM THE LOWER TENNESSEE VALLEY TO
THE OHIO VALLEY TODAY. A SECONDARY LOW DEVELOPING OVER THE
SOUTHEAST IS EXPECTED TO PULL A WARM FRONT ACROSS THE REGION
LATER TODAY...RESULTING IN WIDESPREAD RAINFALL. DRY WEATHER
RETURNS ON WEDNESDAY, WITH GRADUALLY COOLER CONDITIONS FOR THE
LATTER HALF OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE AS OF 10 AM...
RAIN IS CURRENTLY SPREADING INTO SOUTHERN PORTIONS OF OUR FA AS
EXPECTED. THERE WAS A LITTLE SLEET AT THE ONSET AROUND
FARMVILLE...BUT THAT HAS SINCE ENDED AS TEMPS CONTINUE TO WARM SO
HAVE REMOVED MENTION FROM THE FORECAST. OTW...RAIN CONTINUES TO
SPREAD NORTH THROUGH THE DAY WITH NO OTHER CHANGES TO THE FORECAST
NEEDED AT THIS TIME.
PREVIOUS DISCUSSION... LATEST WATER VAPOR IMAGERY
SHOWS STRONG UPPER LOW LOCATED OVER THE LOWER MISSISSIPPI RVR
VALLEY EARLY THIS MORNING. AT THE SFC...POWERFUL AREA OF SFC LOW
PRESSURE CONTINUES TO LIFT NE ACROSS THE OZARKS/CENTRAL MS VLY,
WITH A WELL-DEFINED WARM CONVEYOR BELT EVIDENT ON IR/WV SAT
IMAGERY SPREADING PCPN ACROSS THE TN AND LOWER OH VLYS. FARTHER
SOUTH, A WARM FRONT WAS ANALYZED ALONG THE GULF COAST...EXTENDING
NEWD ALONG THE SE COAST. SECONDARY LOW PRESSURE WAS BEGINNING TO
DEVELOP ACROSS THE GULF COAST, WITH MSAS 3-HR PRESSURE FALLS ON
THE ORDER OF 3-4MB OVER S MS/GA. FINALLY, TO THE NORTH ~1024MB SFC
HIGH PRESSURE HAS RETREATED INTO THE NORTHEAST US, BUT CONTINUES
TO NOSE DOWN THE EAST COAST THIS MORNING.
INCREASING ISENTROPIC LIFT/SWLY FLOW WILL CONTINUE TO ADVECT
UPPER/MID LEVEL MOISTURE INTO THE REGION OVER THE NEXT FEW HOURS.
REGIONAL RADAR MOSAIC INDICATING PRECIP BREAKING OUT ACROSS
WESTERN CAROLINAS AT THIS HOUR, AND LIKELY NOT TO PUSH INTO FAR SW
CORNER OF AKQ CWA UNTIL AFTER SUNRISE. HAVE AGAIN LOWERED POP FOR
THE NEXT FEW HOURS, WITH HRRR DOING A GOOD JOB THUS FAR IN TIMING
PCPN SHIELD. HV LEANED IN ITS DIRECTION IN FURTHER SLOWING ONSET
OF POPS THIS MORNING, ESPECIALLY EASTERN SHORE COUNTIES.
AS EXPECTED, DRY ANTECEDENT AIRMASS OVER THE AREA HAS MODIFIED
LITTLE OVER THE PAST FEW HOURS, WITH DEWPOINTS STILL IN THE TEENS
TO LOW 20S ACROSS OUR E VA PIEDMONT COUNTIES. THUS, PRECIP STILL
SEVERAL HRS OFF. AS PRECIP BREAKS OUT ACROSS THE REGION AFTER
11-12Z, EXPECT THAT A BRIEF PERIOD OF SLEET WL MIX WITH RAIN, MOST
PREVALENT OVER OUR PIEDMONT COUNTIES. HOWEVER, AS SLUG OF
OVERRUNNING MOISTURE CONTINUES TO DRAW CLOSER AND DRIER AIR
CONTINUES TO ERODE, EXPECT DURATION OF ANY NON-LIQUID PCPN TO BE
QUITE BRIEF IN DURATION. NO ICE ACCRETION IS EXPECTED ON ROADWAYS.
THEREFORE, NO WINTER HEADLINES ARE NECESSARY ATTM.
FORECAST DETAILS HAVE CHANGED VERY LITTLE FROM PREVIOUS THINKING,
WITH A GENERAL MODEL CONSENSUS CONTINUES TO FAVOR TAKING THE SFC
LOW FROM CURRENT POSITION OVER E AR JUST SE OF KSTL INTO DOWNSTATE
IL BY TONIGHT. MEANWHILE, SECONDARY SFC LOW LOOKS TO SLIDE FROM
THE CENTRAL GULF COAST ACROSS THE COASTAL CAROLINAS. RAIN CHANCES
RATCHET UP QUICKLY THIS MORNING INTO THE AFTN AS WARM FRONT SLIPS
NORTH AND VERY MOIST AIRMASS PUSHES INTO THE AREA. SLUG OF STEADY
RAIN (MOD TO HVY AT TIMES) STILL LOOKS TO PUSH SW TO NE ACROSS THE
AREA FROM MID MORNING INTO THE EARLY EVENING, WITH RAIN ENDING
FROM S TO N AS WARM FRONT LIFTS NORTH OF THE AREA.
RAINFALL AMOUNTS WILL AVERAGE 0.65" TO 1.00" FOR THIS EVENT. NO
PROBLEMS EXPECTED WITH FLASH FLOOD GUIDANCE, SO NO HYDRO HEADLINES
ISSUED OR ANTICIPATED. REGARDING CONVECTIVE POTENTIAL OUTLOOKED
IN PREVIOUS DISCUSSIONS, SPC NOW HAS AREA OUTLOOKED IN A `GENERAL
THUNDER` AREA, WITH SLIGHT RISK SHUNTED FARTHER SOUTHEAST. THIS
JIVES WELL WITH CURRENT THINKING AS IT APPEARS THAT WARM SECTOR
REMAINS ORIENTED JUST SOUTHEAST OF THE AREA ACROSS FAR SE NC AND
POINTS SOUTH. NAM REMAINS MOST BULLISH WITH MLCAPE, WITH THE GFS
PREFERRING TO TAKE THE SECONDARY LOW ACROSS COASTAL CAROLINAS AS
THE NAM PUSHES LOW INLAND. NAM SOLN WOULD TAKE THE SFC LOW INTO
THE CORE OF THE STABLE CAD WEDGE. THE COOLER, MORE STABLE GFS
SOLUTION FOR THE LOCAL AREA APPEARS MOST LOGICAL...AND THE
FORECAST HAS BEEN TRENDED IN THIS DIRECTION.
FOR HIGHS, AS IS TYPICAL WITH STRONG CAD WEDGE SETUPS, GRADIENT
FROM PIEDMONT TO COASTAL NC COUNTIES WILL VARY BY 20-25 DEG F.
MAX TEMPS WILL RANGE FM THE LWR 40S NW...TO AROUND 60 IN NE NC.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
WEDNESDAY AND THURSDAY GENERALLY CHARACTERIZED BY DEVELOPING UPPER
TROUGH OVER THE EASTERN CONUS, RESULTING IN GRADUALLY COOLER
CONDITIONS FOR THE MID TO LATE WEEK PERIOD.
SFC LOW AND ASSOCIATED FRONTAL BOUNDARY LIFT NE INTO NEW ENGLAND
EARLY ON WED AS UPPER LOW LINGERS OVER THE OHIO VALLEY/EASTERN
GREAT LAKES. DEEP WSW FLOW IN PLACE WILL BRING A MILD AFTERNOON
WITH HIGH TEMPERATURES IN THE UPR 50S TO MID 60S UNDER A PARTLY
SUNNY SKY. THE UPPER LOW MOVES EAST THROUGH PA ON THURSDAY WITH
THE MAJORITY OF THE MOISTURE/ENERGY WITH THIS SYSTEM STAYING TO
OUR NORTH. HOWEVER...HPC SOLN AS WELL AS THE ECMWF AND ITS
ENSEMBLES DO SUPPORT SHORTWAVE ENERGY PINWHEELING BEHIND THE
SYSTEM AND PIVOTING ACROSS THE REGION ON THURSDAY. PLUMES INDICATE
THIS WOULDN`T BE MUCH, BUT SOME SPOTTY SHRAS CAN`T BE RULED OUT
ACROSS NORTHERN/WESTERN SECTIONS ON THURSDAY. HAVE KEPT SLIGHT
CHC POPS (20%) IN PLACE AS A RESULT. OTHERWISE, EXPECT PARTLY
CLOUDY SKY EARLY GIVING WAY TO AFTN/EVENING CLEARING.
FOR TEMPERATURES, LOWS WED NIGHT IN THE 30S TO ~40. FORECAST HIGH
THU IN THE M/U 40S NORTH TO LOW 50S SOUTH.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
ANOMALOUS UPR LVL TROUGH TO REMAIN OVER THE ERN CONUS THROUGH THE
WEEKEND AND EARLY NEXT WEEK. THE TROUGH IS FCST TO SHIFT E/JUST
OFF THE COAST BY ERY NEXT WK. HV CONT W/ DRY FCST...W/ TEMPS TO
AVG ~10F (AOUND 1 STANDARD DEVIATION) BELOW NORMAL AND EACH DAY
HAVING VRB CLDNS/PCLDY NGTS. HI TEMPS RANGING THROUGH THE 40S.
MOST LO TEMPS FM THE M/U20S TO L30S.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
A WARM FRONT CURRENTLY DRAPED ALONG THE CAROLINA COAST WILL
GRADUALLY LIFT INTO THE MID ATLANTIC REGION THIS AFTERNOON AS A
COMPLEX LOW PRESSURE SYSTEM APPROACHES THE AREA FROM THE SOUTHWEST
TODAY. OVERRUNNING PRECIPITATION AND LOWER CIGS ASSOCIATED WITH
THE WARM FRONT WILL SPREAD INTO THE MID ATLANTIC REGION FROM THE
SOUTHWEST THIS MORNING AND BEGIN TO IMPACT KRIC...KPHF...KORF...AND
KECG AFTER 26/1600Z. DURING THIS AFTERNOON...RAINFALL WILL BECOME
MODERATE TO HEAVY AT TIMES (LOWERING CIGS TWD 500 FT AGL) AND E-SE
WINDS WILL BECOME BREEZY WITH GUSTS AROUND 25-30 KT. KSBY WILL
BEGIN TO EXPERIENCE SIMILAR CONDITIONS AFTER 26/2000Z.
PRECIPITATION WILL COME TO AN END FROM SOUTHWEST TO NORTHEAST
THROUGH TUESDAY EVENING AS LOW PRESSURE MOVES NORTHEAST AND OUT OF
THE AREA AFTER MIDNIGHT. BREEZY WINDS OVERNIGHT WILL HELP TO SCOUR
OUT LOWER CIGS AND IMPROVE VISIBILITIES ONCE PRECIP COMES TO AN END.
&&
.MARINE...
SCA HEADLINES HAVE BEEN ADJUSTED TO BEGIN EARLY THIS MORNING WITH
THE EXCEPTION OF CURRITUCK SOUND AND NRN COASTAL WATERS WHERE
WINDS WILL NOT INCREASE UNTIL THIS AFTN. HAVE ALREADY BEGUN TO SEE
A SLIGHT INCREASE IN WINDS OVER THE SRN BAY AS HIGH PRESSURE NOW
RESIDES OVER NEW ENGLAND AND THE PRESSURE GRADIENT TIGHTENS IN
RESPONSE TO THE APPROACHING LOW PRESSURE SYSTEM TO THE SOUTHWEST.
EAST WINDS ARE GENERALLY AOB 15 KT...HOWEVER THEY WILL TURN SE
AND INCREASE THIS AFTN...GUSTING BTWN 25-40 KT (DEPENDING ON
LOCATION). SE WINDS WILL PEAK EARLY THIS EVENING...THEN BECOME SW
AND DECREASE AFTER MIDNIGHT TONIGHT. SEAS ARE GENERALLY 4-5 FT
EARLY THIS MORNING AND WILL ALSO INCREASE TO 7-10 FT DURING THE
AFTN AND OVERNIGHT AS LOW PRESSURE MOVES UP THE MID ATLANTIC
SEABOARD AND INTENSIFIES.
AS THE LOW MOVES NORTH OF AREA WATERS...WARM MARINE AIR CONTINUED
TO BE PULLED INTO THE STORM AND WILL ACT TO INHIBIT ADDITIONAL
MIXING IN THE WAKE OF THE LOW. AFTER THAT...A PROLONGED PERIOD OF
OFFSHORE WINDS PREVAILS WED THROUGH AT LEAST FRIDAY. WINDS WILL
INITIALLY BE WSW ON WED...THEN WNW THU INTO THE WEEKEND. THE
POTENTIAL FOR EXTENDED SCA FLAGS EXISTS DURING THIS TIME DUE TO A
LONG PERIOD OF LOW LEVEL CAA...RESULTING IN WIND SPEEDS AOA 20-25 KT
AT TIMES.
&&
.TIDES/COASTAL FLOODING...
TIDAL ANOMALIES ARE STILL RUNNING ABOUT 0.5 TO 1.0 FT ABOVE
NORMAL...ESPECIALLY DURING THE HIGH TIDE CYCLE TO OCCUR THIS
EVENING. OVERALL WATER LEVELS ARE EXPECTED TO STAY ABOUT 1-2 FT
BELOW MINOR FLOODING THRESHOLDS...BUT WILL NEED TO MONITOR LATEST
FORECASTS CLOSELY DUE TO INCREASING E-SE WINDS THIS AFTN AND
EVENING.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR ANZ635>638.
SMALL CRAFT ADVISORY UNTIL 10 AM EST WEDNESDAY FOR ANZ630>632-
634.
SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR ANZ633.
GALE WARNING UNTIL 1 AM EST WEDNESDAY FOR ANZ650-652-654.
SMALL CRAFT ADVISORY UNTIL 1 AM EST THURSDAY FOR ANZ656.
SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR ANZ658.
&&
$$
SYNOPSIS...MAM
NEAR TERM...JDM/MAM
SHORT TERM...MAM
LONG TERM...ALB
AVIATION...BMD
MARINE...BMD
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
513 AM EST TUE FEB 26 2013
.SYNOPSIS...
STRONG LOW PRESSURE WILL TRACK FROM THE LOWER TENNESSEE VALLEY TO
THE OHIO VALLEY TODAY. A SECONDARY LOW DEVELOPING OVER THE
SOUTHEAST IS EXPECTED TO PULL A WARM FRONT ACROSS THE REGION
LATER TODAY...RESULTING IN WIDESPREAD RAINFALL. DRY WEATHER
RETURNS ON WEDNESDAY, WITH GRADUALLY COOLER CONDITIONS FOR THE
LATTER HALF OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST WATER VAPOR IMAGERY SHOWS STRONG UPPER LOW LOCATED OVER THE
LOWER MISSISSIPPI RVR VALLEY EARLY THIS MORNING. AT THE
SFC...POWERFUL AREA OF SFC LOW PRESSURE CONTINUES TO LIFT NE
ACROSS THE OZARKS/CENTRAL MS VLY, WITH A WELL-DEFINED WARM
CONVEYOR BELT EVIDENT ON IR/WV SAT IMAGERY SPREADING PCPN ACROSS
THE TN AND LOWER OH VLYS. FARTHER SOUTH, A WARM FRONT WAS ANALYZED
ALONG THE GULF COAST...EXTENDING NEWD ALONG THE SE COAST.
SECONDARY LOW PRESSURE WAS BEGINNING TO DEVELOP ACROSS THE GULF
COAST, WITH MSAS 3-HR PRESSURE FALLS ON THE ORDER OF 3-4MB OVER S
MS/GA. FINALLY, TO THE NORTH ~1024MB SFC HIGH PRESSURE HAS
RETREATED INTO THE NORTHEAST US, BUT CONTINUES TO NOSE DOWN THE
EAST COAST THIS MORNING.
INCREASING ISENTROPIC LIFT/SWLY FLOW WILL CONTINUE TO ADVECT
UPPER/MID LEVEL MOISTURE INTO THE REGION OVER THE NEXT FEW HOURS.
REGIONAL RADAR MOSAIC INDICATING PRECIP BREAKING OUT ACROSS
WESTERN CAROLINAS AT THIS HOUR, AND LIKELY NOT TO PUSH INTO FAR SW
CORNER OF AKQ CWA UNTIL AFTER SUNRISE. HAVE AGAIN LOWERED POP FOR
THE NEXT FEW HOURS, WITH HRRR DOING A GOOD JOB THUS FAR IN TIMING
PCPN SHIELD. HV LEANED IN ITS DIRECTION IN FURTHER SLOWING ONSET
OF POPS THIS MORNING, ESPECIALLY EASTERN SHORE COUNTIES.
AS EXPECTED, DRY ANTECEDENT AIRMASS OVER THE AREA HAS MODIFIED
LITTLE OVER THE PAST FEW HOURS, WITH DEWPOINTS STILL IN THE TEENS
TO LOW 20S ACROSS OUR E VA PIEDMONT COUNTIES. THUS, PRECIP STILL
SEVERAL HRS OFF. AS PRECIP BREAKS OUT ACROSS THE REGION AFTER
11-12Z, EXPECT THAT A BRIEF PERIOD OF SLEET WL MIX WITH RAIN, MOST
PREVALENT OVER OUR PIEDMONT COUNTIES. HOWEVER, AS SLUG OF
OVERRUNNING MOISTURE CONTINUES TO DRAW CLOSER AND DRIER AIR
CONTINUES TO ERODE, EXPECT DURATION OF ANY NON-LIQUID PCPN TO BE
QUITE BRIEF IN DURATION. NO ICE ACCRETION IS EXPECTED ON ROADWAYS.
THEREFORE, NO WINTER HEADLINES ARE NECESSARY ATTM.
FORECAST DETAILS HAVE CHANGED VERY LITTLE FROM PREVIOUS THINKING,
WITH A GENERAL MODEL CONSENSUS CONTINUES TO FAVOR TAKING THE SFC
LOW FROM CURRENT POSITION OVER E AR JUST SE OF KSTL INTO DOWNSTATE
IL BY TONIGHT. MEANWHILE, SECONDARY SFC LOW LOOKS TO SLIDE FROM
THE CENTRAL GULF COAST ACROSS THE COASTAL CAROLINAS. RAIN CHANCES
RATCHET UP QUICKLY THIS MORNING INTO THE AFTN AS WARM FRONT SLIPS
NORTH AND VERY MOIST AIRMASS PUSHES INTO THE AREA. SLUG OF STEADY
RAIN (MOD TO HVY AT TIMES) STILL LOOKS TO PUSH SW TO NE ACROSS THE
AREA FROM MID MORNING INTO THE EARLY EVENING, WITH RAIN ENDING
FROM S TO N AS WARM FRONT LIFTS NORTH OF THE AREA.
RAINFALL AMOUNTS WILL AVERAGE 0.65" TO 1.00" FOR THIS EVENT. NO
PROBLEMS EXPECTED WITH FLASH FLOOD GUIDANCE, SO NO HYDRO HEADLINES
ISSUED OR ANTICIPATED. REGARDING CONVECTIVE POTENTIAL OUTLOOKED
IN PREVIOUS DISCUSSIONS, SPC NOW HAS AREA OUTLOOKED IN A `GENERAL
THUNDER` AREA, WITH SLIGHT RISK SHUNTED FARTHER SOUTHEAST. THIS
JIVES WELL WITH CURRENT THINKING AS IT APPEARS THAT WARM SECTOR
REMAINS ORIENTED JUST SOUTHEAST OF THE AREA ACROSS FAR SE NC AND
POINTS SOUTH. NAM REMAINS MOST BULLISH WITH MLCAPE, WITH THE GFS
PREFERRING TO TAKE THE SECONDARY LOW ACROSS COASTAL CAROLINAS AS
THE NAM PUSHES LOW INLAND. NAM SOLN WOULD TAKE THE SFC LOW INTO
THE CORE OF THE STABLE CAD WEDGE. THE COOLER, MORE STABLE GFS
SOLUTION FOR THE LOCAL AREA APPEARS MOST LOGICAL...AND THE
FORECAST HAS BEEN TRENDED IN THIS DIRECTION.
FOR HIGHS, AS IS TYPICAL WITH STRONG CAD WEDGE SETUPS, GRADIENT
FROM PIEDMONT TO COASTAL NC COUNTIES WILL VARY BY 20-25 DEG F.
MAX TEMPS WILL RANGE FM THE LWR 40S NW...TO AROUND 60 IN NE NC.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
WEDNESDAY AND THURSDAY GENERALLY CHARACTERIZED BY DEVELOPING UPPER
TROUGH OVER THE EASTERN CONUS, RESULTING IN GRADUALLY COOLER
CONDITIONS FOR THE MID TO LATE WEEK PERIOD.
SFC LOW AND ASSOCIATED FRONTAL BOUNDARY LIFT NE INTO NEW ENGLAND
EARLY ON WED AS UPPER LOW LINGERS OVER THE OHIO VALLEY/EASTERN
GREAT LAKES. DEEP WSW FLOW IN PLACE WILL BRING A MILD AFTERNOON
WITH HIGH TEMPERATURES IN THE UPR 50S TO MID 60S UNDER A PARTLY
SUNNY SKY. THE UPPER LOW MOVES EAST THROUGH PA ON THURSDAY WITH
THE MAJORITY OF THE MOISTURE/ENERGY WITH THIS SYSTEM STAYING TO
OUR NORTH. HOWEVER...HPC SOLN AS WELL AS THE ECMWF AND ITS
ENSEMBLES DO SUPPORT SHORTWAVE ENERGY PINWHEELING BEHIND THE
SYSTEM AND PIVOTING ACROSS THE REGION ON THURSDAY. PLUMES INDICATE
THIS WOULDN`T BE MUCH, BUT SOME SPOTTY SHRAS CAN`T BE RULED OUT
ACROSS NORTHERN/WESTERN SECTIONS ON THURSDAY. HAVE KEPT SLIGHT
CHC POPS (20%) IN PLACE AS A RESULT. OTHERWISE, EXPECT PARTLY
CLOUDY SKY EARLY GIVING WAY TO AFTN/EVENING CLEARING.
FOR TEMPERATURES, LOWS WED NIGHT IN THE 30S TO ~40. FORECAST HIGH
THU IN THE M/U 40S NORTH TO LOW 50S SOUTH.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
ANOMALOUS UPR LVL TROUGH TO REMAIN OVER THE ERN CONUS THROUGH THE
WEEKEND AND EARLY NEXT WEEK. THE TROUGH IS FCST TO SHIFT E/JUST
OFF THE COAST BY ERY NEXT WK. HV CONT W/ DRY FCST...W/ TEMPS TO
AVG ~10F (AOUND 1 STANDARD DEVIATION) BELOW NORMAL AND EACH DAY
HAVING VRB CLDNS/PCLDY NGTS. HI TEMPS RANGING THROUGH THE 40S.
MOST LO TEMPS FM THE M/U20S TO L30S.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
A WARM FRONT CURRENTLY DRAPED ALONG THE CAROLINA COAST WILL
GRADUALLY LIFT INTO THE MID ATLANTIC REGION THIS AFTERNOON AS A
COMPLEX LOW PRESSURE SYSTEM APPROACHES THE AREA FROM THE SOUTHWEST
TODAY. OVERRUNNING PRECIPITATION AND LOWER CIGS ASSOCIATED WITH
THE WARM FRONT WILL SPREAD INTO THE MID ATLANTIC REGION FROM THE
SOUTHWEST THIS MORNING AND BEGIN TO IMPACT KRIC...KPHF...KORF...AND
KECG AFTER 26/1600Z. DURING THIS AFTERNOON...RAINFALL WILL BECOME
MODERATE TO HEAVY AT TIMES (LOWERING CIGS TWD 500 FT AGL) AND E-SE
WINDS WILL BECOME BREEZY WITH GUSTS AROUND 25-30 KT. KSBY WILL
BEGIN TO EXPERIENCE SIMILAR CONDITIONS AFTER 26/2000Z.
PRECIPITATION WILL COME TO AN END FROM SOUTHWEST TO NORTHEAST
THROUGH TUESDAY EVENING AS LOW PRESSURE MOVES NORTHEAST AND OUT OF
THE AREA AFTER MIDNIGHT. BREEZY WINDS OVERNIGHT WILL HELP TO SCOUR
OUT LOWER CIGS AND IMPROVE VISIBILITIES ONCE PRECIP COMES TO AN END.
&&
.MARINE...
SCA HEADLINES HAVE BEEN ADJUSTED TO BEGIN EARLY THIS MORNING WITH
THE EXCEPTION OF CURRITUCK SOUND AND NRN COASTAL WATERS WHERE
WINDS WILL NOT INCREASE UNTIL THIS AFTN. HAVE ALREADY BEGUN TO SEE
A SLIGHT INCREASE IN WINDS OVER THE SRN BAY AS HIGH PRESSURE NOW
RESIDES OVER NEW ENGLAND AND THE PRESSURE GRADIENT TIGHTENS IN
RESPONSE TO THE APPROACHING LOW PRESSURE SYSTEM TO THE SOUTHWEST.
EAST WINDS ARE GENERALLY AOB 15 KT...HOWEVER THEY WILL TURN SE
AND INCREASE THIS AFTN...GUSTING BTWN 25-40 KT (DEPENDING ON
LOCATION). SE WINDS WILL PEAK EARLY THIS EVENING...THEN BECOME SW
AND DECREASE AFTER MIDNIGHT TONIGHT. SEAS ARE GENERALLY 4-5 FT
EARLY THIS MORNING AND WILL ALSO INCREASE TO 7-10 FT DURING THE
AFTN AND OVERNIGHT AS LOW PRESSURE MOVES UP THE MID ATLANTIC
SEABOARD AND INTENSIFIES.
AS THE LOW MOVES NORTH OF AREA WATERS...WARM MARINE AIR CONTINUED
TO BE PULLED INTO THE STORM AND WILL ACT TO INHIBIT ADDITIONAL
MIXING IN THE WAKE OF THE LOW. AFTER THAT...A PROLONGED PERIOD OF
OFFSHORE WINDS PREVAILS WED THROUGH AT LEAST FRIDAY. WINDS WILL
INITIALLY BE WSW ON WED...THEN WNW THU INTO THE WEEKEND. THE
POTENTIAL FOR EXTENDED SCA FLAGS EXISTS DURING THIS TIME DUE TO A
LONG PERIOD OF LOW LEVEL CAA...RESULTING IN WIND SPEEDS AOA 20-25 KT
AT TIMES.
&&
.TIDES/COASTAL FLOODING...
TIDAL ANOMALIES ARE STILL RUNNING ABOUT 0.5 TO 1.0 FT ABOVE
NORMAL...ESPECIALLY DURING THE HIGH TIDE CYCLE TO OCCUR THIS
EVENING. OVERALL WATER LEVELS ARE EXPECTED TO STAY ABOUT 1-2 FT
BELOW MINOR FLOODING THRESHOLDS...BUT WILL NEED TO MONITOR LATEST
FORECASTS CLOSELY DUE TO INCREASING E-SE WINDS THIS AFTN AND
EVENING.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR ANZ635>638.
SMALL CRAFT ADVISORY UNTIL 10 AM EST WEDNESDAY FOR ANZ630>632-
634.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 1 AM EST WEDNESDAY FOR
ANZ633.
SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR ANZ650-
652-654.
GALE WARNING FROM 4 PM THIS AFTERNOON TO 1 AM EST WEDNESDAY
FOR ANZ650-652-654.
SMALL CRAFT ADVISORY UNTIL 1 AM EST THURSDAY FOR ANZ656.
SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR ANZ658.
&&
$$
SYNOPSIS...MAM
NEAR TERM...JDM/MAM
SHORT TERM...MAM
LONG TERM...ALB
AVIATION...BMD
MARINE...BMD
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
505 AM EST TUE FEB 26 2013
.SYNOPSIS...
STRONG LOW PRESSURE WILL TRACK FROM THE LOWER TENNESSEE VALLEY TO
THE GREAT LAKES TODAY. A SECONDARY LOW DEVELOPING OVER THE
SOUTHERN APPALACHIANS IS EXPECTED TO PULLING A WARM FRONT UP INTO
THE REGION LATER TODAY...RESULTING IN WIDESPREAD RAINFALL. DRY
WEATHER RETURNS ON WEDNESDAY, WITH GRADUALLY COOLER CONDITIONS
FOR THE LATTER HALF OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST WATER VAPOR IMAGERY SHOWS STRONG UPPER LOW LOCATED OVER THE
LOWER MISSISSIPPI RVR VALLEY EARLY THIS MORNING. AT THE
SFC...POWERFUL AREA OF SFC LOW PRESSURE CONTINUES TO LIFT NE
ACROSS THE OZARKS/CENTRAL MS VLY, WITH A WELL-DEFINED WARM
CONVEYOR BELT EVIDENT ON IR/WV SAT IMAGERY SPREADING PCPN ACROSS
THE TN AND LOWER OH VLYS. FARTHER SOUTH, A WARM FRONT WAS ANALYZED
ALONG THE GULF COAST...EXTENDING NEWD ALONG THE SE COAST.
SECONDARY LOW PRESSURE WAS BEGINNING TO DEVELOP ACROSS THE GULF
COAST, WITH MSAS 3-HR PRESSURE FALLS ON THE ORDER OF 3-4MB OVER S
MS/GA. FINALLY, TO THE NORTH ~1024MB SFC HIGH PRESSURE HAS
RETREATED INTO THE NORTHEAST US, BUT CONTINUES TO NOSE DOWN THE
EAST COAST THIS MORNING.
INCREASING ISENTROPIC LIFT/SWLY FLOW WILL CONTINUE TO ADVECT
UPPER/MID LEVEL MOISTURE INTO THE REGION OVER THE NEXT FEW HOURS.
REGIONAL RADAR MOSAIC INDICATING PRECIP BREAKING OUT ACROSS
WESTERN CAROLINAS AT THIS HOUR, AND LIKELY NOT TO PUSH INTO FAR SW
CORNER OF AKQ CWA UNTIL AFTER SUNRISE. HAVE AGAIN LOWERED POP FOR
THE NEXT FEW HOURS, WITH HRRR DOING A GOOD JOB THUS FAR IN TIMING
PCPN SHIELD. HV LEANED IN ITS DIRECTION IN FURTHER SLOWING ONSET
OF POPS THIS MORNING, ESPECIALLY EASTERN SHORE COUNTIES.
AS EXPECTED, DRY ANTECEDENT AIRMASS OVER THE AREA HAS MODIFIED
LITTLE OVER THE PAST FEW HOURS, WITH DEWPOINTS STILL IN THE TEENS
TO LOW 20S ACROSS OUR E VA PIEDMONT COUNTIES. THUS, PRECIP STILL
SEVERAL HRS OFF. AS PRECIP BREAKS OUT ACROSS THE REGION AFTER
11-12Z, EXPECT THAT A BRIEF PERIOD OF SLEET WL MIX WITH RAIN, MOST
PREVALENT OVER OUR PIEDMONT COUNTIES. HOWEVER, AS SLUG OF
OVERRUNNING MOISTURE CONTINUES TO DRAW CLOSER AND DRIER AIR
CONTINUES TO ERODE, EXPECT DURATION OF ANY NON-LIQUID PCPN TO BE
QUITE BRIEF IN DURATION. NO ICE ACCRETION IS EXPECTED ON ROADWAYS.
THEREFORE, NO WINTER HEADLINES ARE NECESSARY ATTM.
FORECAST DETAILS HAVE CHANGED VERY LITTLE FROM PREVIOUS THINKING,
WITH A GENERAL MODEL CONSENSUS CONTINUES TO FAVOR TAKING THE SFC
LOW FROM CURRENT POSITION OVER E AR JUST SE OF KSTL INTO DOWNSTATE
IL BY TONIGHT. MEANWHILE, SECONDARY SFC LOW LOOKS TO SLIDE FROM
THE CENTRAL GULF COAST ACROSS THE COASTAL CAROLINAS. RAIN CHANCES
RATCHET UP QUICKLY THIS MORNING INTO THE AFTN AS WARM FRONT SLIPS
NORTH AND VERY MOIST AIRMASS PUSHES INTO THE AREA. SLUG OF STEADY
RAIN (MOD TO HVY AT TIMES) STILL LOOKS TO PUSH SW TO NE ACROSS THE
AREA FROM MID MORNING INTO THE EARLY EVENING, WITH RAIN ENDING
FROM S TO N AS WARM FRONT LIFTS NORTH OF THE AREA.
RAINFALL AMOUNTS WILL AVERAGE 0.65" TO 1.00" FOR THIS EVENT. NO
PROBLEMS EXPECTED WITH FLASH FLOOD GUIDANCE, SO NO HYDRO HEADLINES
ISSUED OR ANTICIPATED. REGARDING CONVECTIVE POTENTIAL OUTLOOKED
IN PREVIOUS DISCUSSIONS, SPC NOW HAS AREA OUTLOOKED IN A `GENERAL
THUNDER` AREA, WITH SLIGHT RISK SHUNTED FARTHER SOUTHEAST. THIS
JIVES WELL WITH CURRENT THINKING AS IT APPEARS THAT WARM SECTOR
REMAINS ORIENTED JUST SOUTHEAST OF THE AREA ACROSS FAR SE NC AND
POINTS SOUTH. NAM REMAINS MOST BULLISH WITH MLCAPE, WITH THE GFS
PREFERRING TO TAKE THE SECONDARY LOW ACROSS COASTAL CAROLINAS AS
THE NAM PUSHES LOW INLAND. NAM SOLN WOULD TAKE THE SFC LOW INTO
THE CORE OF THE STABLE CAD WEDGE. THE COOLER, MORE STABLE GFS
SOLUTION FOR THE LOCAL AREA APPEARS MOST LOGICAL...AND THE
FORECAST HAS BEEN TRENDED IN THIS DIRECTION.
FOR HIGHS, AS IS TYPICAL WITH STRONG CAD WEDGE SETUPS, GRADIENT
FROM PIEDMONT TO COASTAL NC COUNTIES WILL VARY BY 20-25 DEG F.
MAX TEMPS WILL RANGE FM THE LWR 40S NW...TO AROUND 60 IN NE NC.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
WEDNESDAY AND THURSDAY GENERALLY CHARACTERIZED BY DEVELOPING UPPER
TROUGH OVER THE EASTERN CONUS, RESULTING IN GRADUALLY COOLER
CONDITIONS FOR THE MID TO LATE WEEK PERIOD.
SFC LOW AND ASSOCIATED FRONTAL BOUNDARY LIFT NE INTO NEW ENGLAND
EARLY ON WED AS UPPER LOW LINGERS OVER THE OHIO VALLEY/EASTERN
GREAT LAKES. DEEP WSW FLOW IN PLACE WILL BRING A MILD AFTERNOON
WITH HIGH TEMPERATURES IN THE UPR 50S TO MID 60S UNDER A PARTLY
SUNNY SKY. THE UPPER LOW MOVES EAST THROUGH PA ON THURSDAY WITH
THE MAJORITY OF THE MOISTURE/ENERGY WITH THIS SYSTEM STAYING TO
OUR NORTH. HOWEVER...HPC SOLN AS WELL AS THE ECMWF AND ITS
ENSEMBLES DO SUPPORT SHORTWAVE ENERGY PINWHEELING BEHIND THE
SYSTEM AND PIVOTING ACROSS THE REGION ON THURSDAY. PLUMES INDICATE
THIS WOULDN`T BE MUCH, BUT SOME SPOTTY SHRAS CAN`T BE RULED OUT
ACROSS NORTHERN/WESTERN SECTIONS ON THURSDAY. HAVE KEPT SLIGHT
CHC POPS (20%) IN PLACE AS A RESULT. OTHERWISE, EXPECT PARTLY
CLOUDY SKY EARLY GIVING WAY TO AFTN/EVENING CLEARING.
FOR TEMPERATURES, LOWS WED NIGHT IN THE 30S TO ~40. FORECAST HIGH
THU IN THE M/U 40S NORTH TO LOW 50S SOUTH.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
ANOMALOUS UPR LVL TROUGH TO REMAIN OVER THE ERN CONUS THROUGH THE
WEEKEND AND EARLY NEXT WEEK. THE TROUGH IS FCST TO SHIFT E/JUST
OFF THE COAST BY ERY NEXT WK. HV CONT W/ DRY FCST...W/ TEMPS TO
AVG ~10F (AOUND 1 STANDARD DEVIATION) BELOW NORMAL AND EACH DAY
HAVING VRB CLDNS/PCLDY NGTS. HI TEMPS RANGING THROUGH THE 40S.
MOST LO TEMPS FM THE M/U20S TO L30S.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
A WARM FRONT CURRENTLY DRAPED ALONG THE CAROLINA COAST WILL
GRADUALLY LIFT INTO THE MID ATLANTIC REGION THIS AFTERNOON AS A
COMPLEX LOW PRESSURE SYSTEM APPROACHES THE AREA FROM THE SOUTHWEST
TODAY. OVERRUNNING PRECIPITATION AND LOWER CIGS ASSOCIATED WITH
THE WARM FRONT WILL SPREAD INTO THE MID ATLANTIC REGION FROM THE
SOUTHWEST THIS MORNING AND BEGIN TO IMPACT KRIC...KPHF...KORF...AND
KECG AFTER 26/1600Z. DURING THIS AFTERNOON...RAINFALL WILL BECOME
MODERATE TO HEAVY AT TIMES (LOWERING CIGS TWD 500 FT AGL) AND E-SE
WINDS WILL BECOME BREEZY WITH GUSTS AROUND 25-30 KT. KSBY WILL
BEGIN TO EXPERIENCE SIMILAR CONDITIONS AFTER 26/2000Z.
PRECIPITATION WILL COME TO AN END FROM SOUTHWEST TO NORTHEAST
THROUGH TUESDAY EVENING AS LOW PRESSURE MOVES NORTHEAST AND OUT OF
THE AREA AFTER MIDNIGHT. BREEZY WINDS OVERNIGHT WILL HELP TO SCOUR
OUT LOWER CIGS AND IMPROVE VISIBILITIES ONCE PRECIP COMES TO AN END.
&&
.MARINE...
SCA HEADLINES HAVE BEEN ADJUSTED TO BEGIN EARLY THIS MORNING WITH
THE EXCEPTION OF CURRITUCK SOUND AND NRN COASTAL WATERS WHERE
WINDS WILL NOT INCREASE UNTIL THIS AFTN. HAVE ALREADY BEGUN TO SEE
A SLIGHT INCREASE IN WINDS OVER THE SRN BAY AS HIGH PRESSURE NOW
RESIDES OVER NEW ENGLAND AND THE PRESSURE GRADIENT TIGHTENS IN
RESPONSE TO THE APPROACHING LOW PRESSURE SYSTEM TO THE SOUTHWEST.
EAST WINDS ARE GENERALLY AOB 15 KT...HOWEVER THEY WILL TURN SE
AND INCREASE THIS AFTN...GUSTING BTWN 25-40 KT (DEPENDING ON
LOCATION). SE WINDS WILL PEAK EARLY THIS EVENING...THEN BECOME SW
AND DECREASE AFTER MIDNIGHT TONIGHT. SEAS ARE GENERALLY 4-5 FT
EARLY THIS MORNING AND WILL ALSO INCREASE TO 7-10 FT DURING THE
AFTN AND OVERNIGHT AS LOW PRESSURE MOVES UP THE MID ATLANTIC
SEABOARD AND INTENSIFIES.
AS THE LOW MOVES NORTH OF AREA WATERS...WARM MARINE AIR CONTINUED
TO BE PULLED INTO THE STORM AND WILL ACT TO INHIBIT ADDITIONAL
MIXING IN THE WAKE OF THE LOW. AFTER THAT...A PROLONGED PERIOD OF
OFFSHORE WINDS PREVAILS WED THROUGH AT LEAST FRIDAY. WINDS WILL
INITIALLY BE WSW ON WED...THEN WNW THU INTO THE WEEKEND. THE
POTENTIAL FOR EXTENDED SCA FLAGS EXISTS DURING THIS TIME DUE TO A
LONG PERIOD OF LOW LEVEL CAA...RESULTING IN WIND SPEEDS AOA 20-25 KT
AT TIMES.
&&
.TIDES/COASTAL FLOODING...
TIDAL ANOMALIES ARE STILL RUNNING ABOUT 0.5 TO 1.0 FT ABOVE
NORMAL...ESPECIALLY DURING THE HIGH TIDE CYCLE TO OCCUR THIS
EVENING. OVERALL WATER LEVELS ARE EXPECTED TO STAY ABOUT 1-2 FT
BELOW MINOR FLOODING THRESHOLDS...BUT WILL NEED TO MONITOR LATEST
FORECASTS CLOSELY DUE TO INCREASING E-SE WINDS THIS AFTN AND
EVENING.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR ANZ635>638.
SMALL CRAFT ADVISORY UNTIL 10 AM EST WEDNESDAY FOR ANZ630>632-
634.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 1 AM EST WEDNESDAY FOR
ANZ633.
SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR ANZ650-
652-654.
GALE WARNING FROM 4 PM THIS AFTERNOON TO 1 AM EST WEDNESDAY
FOR ANZ650-652-654.
SMALL CRAFT ADVISORY UNTIL 1 AM EST THURSDAY FOR ANZ656.
SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR ANZ658.
&&
$$
SYNOPSIS...MAM
NEAR TERM...JDM/MAM
SHORT TERM...MAM
LONG TERM...ALB
AVIATION...BMD
MARINE...BMD
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
500 AM EST TUE FEB 26 2013
.SYNOPSIS...
STRONG LOW PRESSURE WILL TRACK FROM THE LOWER TENNESSEE VALLEY TO
THE GREAT LAKES TODAY. A SECONDARY LOW DEVELOPING OVER THE
SOUTHERN APPALACHIANS IS EXPECTED TO PULLING A WARM FRONT UP INTO
THE REGION LATER TODAY...RESULTING IN WIDESPREAD RAINFALL. DRY
WEATHER RETURNS ON WEDNESDAY, WITH GRADUALLY COOLER CONDITIONS
FOR THE LATTER HALF OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST WATER VAPOR IMAGERY SHOWS STRONG UPPER LOW LOCATED OVER THE
LOWER MISSISSIPPI RVR VALLEY EARLY THIS MORNING. AT THE
SFC...POWERFUL AREA OF SFC LOW PRESSURE CONTINUES TO LIFT NE
ACROSS THE OZARKS/CENTRAL MS VLY, WITH A WELL-DEFINED WARM
CONVEYOR BELT EVIDENT ON IR/WV SAT IMAGERY SPREADING PCPN ACROSS
THE TN AND LOWER OH VLYS. FARTHER SOUTH, A WARM FRONT WAS ANALYZED
ALONG THE GULF COAST...EXTENDING NEWD ALONG THE SE COAST.
SECONDARY LOW PRESSURE WAS BEGINNING TO DEVELOP ACROSS THE GULF
COAST, WITH MSAS 3-HR PRESSURE FALLS ON THE ORDER OF 3-4MB OVER S
MS/GA. FINALLY, TO THE NORTH ~1024MB SFC HIGH PRESSURE HAS
RETREATED INTO THE NORTHEAST US, BUT CONTINUES TO NOSE DOWN THE
EAST COAST THIS MORNING.
INCREASING ISENTROPIC LIFT/SWLY FLOW WILL CONTINUE TO ADVECT
UPPER/MID LEVEL MOISTURE INTO THE REGION OVER THE NEXT FEW HOURS.
REGIONAL RADAR MOSAIC INDICATING PRECIP BREAKING OUT ACROSS
WESTERN CAROLINAS AT THIS HOUR, AND LIKELY NOT TO PUSH INTO FAR SW
CORNER OF AKQ CWA UNTIL AFTER SUNRISE. HAVE AGAIN LOWERED POP FOR
THE NEXT FEW HOURS, WITH HRRR DOING A GOOD JOB THUS FAR IN TIMING
PCPN SHIELD.
AS EXPECTED, DRY ANTECEDENT AIRMASS OVER THE AREA HAS MODIFIED
LITTLE OVER THE PAST FEW HOURS, WITH DEWPOINTS STILL IN THE TEENS
TO LOW 20S ACROSS OUR E VA PIEDMONT COUNTIES. THUS, PRECIP STILL
LKLY SEVERAL HRS OFF. AS PRECIP BREAKS OUT ACROSS THE REGION AFTER
SUNRISE EXPECT A BRIEF PERIOD OF SLEET TO MIX WITH RAIN ACROSS
OUR PIEDMONT COUNTIES. HOWEVER, AS SLUG OF OVERRUNNING MOISTURE
CONTINUES TO DRAW CLOSER AND DRIER AIR CONTINUES TO ERODE, EXPECT
DURATION OF ANY NON-LIQUID PCPN TO BE QUITE BRIEF.
FROM THERE, FORECAST DETAILS HAVE CHANGED VERY LITTLE FROM
PREVIOUS THINKING, WITH A GENERAL MODEL CONSENSUS CONTINUES TO
FAVOR TAKING THE SFC LOW FROM CURRENT POSITION OVER E AR JUST SE
OF KSTL INTO DOWNSTATE IL BY TONIGHT. MEANWHILE, SECONDARY SFC
LOW LOOKS TO SLIDE FROM THE CENTRAL GULF COAST ACROSS THE COASTAL
CAROLINAS. RAIN CHANCES RATCHET UP QUICKLY THIS MORNING INTO THE
AFTN AS WARM FRONT SLIPS NORTH AND VERY MOIST AIRMASS PUSHES INTO
THE AREA. STEADY RAIN LOOKS TO PUSH SW TO NE ACROSS THE AREA FROM
MID MORNING INTO THE EARLY EVENING, WITH RAIN ENDING FROM S TO N
AS WARM FRONT LIFTS NORTH OF THE AREA.
RAINFALL AMOUNTS WILL AVERAGE 0.75" TO 1.50" FOR THIS EVENT. NO
PROBLEMS EXPECTED WITH FLASH FLOOD GUIDANCE, SO NO HEADLINES
ANTICIPATED. SPC HAS AREA OUTLOOKED IN A `GENERAL THUNDER` AREA,
WITH SLIGHT RISK SHUNTED FARTHER SOUTHEAST. THIS JIVES WELL WITH
CURRENT THINKING AS IT APPEARS THAT WARM SECTOR REMAINS ORIENTED
JUST SOUTHEAST OF THE AREA ACROSS FAR SE NC AND POINTS SOUTH. NAM
REMAINS MOST BULLISH WITH MLCAPE. HOWEVER, EVEN THAT SOLUTION
RESULTING IN A MODESTLY UNSTABLE AIRMASS ALOFT, WITH THE BL LKLY
REMAINING STABLE THROUGHOUT.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
WEDNESDAY AND THURSDAY GENERALLY CHARACTERIZED BY DEVELOPING UPPER
TROUGH OVER THE EASTERN CONUS, RESULTING IN GRADUALLY COOLER
CONDITIONS FOR THE MID TO LATE WEEK PERIOD.
SFC LOW AND ASSOCIATED FRONTAL BOUNDARY LIFT NE INTO NEW ENGLAND
EARLY ON WED AS UPPER LOW LINGERS OVER THE OHIO VALLEY/EASTERN
GREAT LAKES. DEEP WSW FLOW IN PLACE WILL BRING A MILD AFTERNOON
WITH HIGH TEMPERATURES IN THE UPR 50S TO MID 60S UNDER A PARTLY
SUNNY SKY. THE UPPER LOW MOVES EAST THROUGH PA ON THURSDAY WITH
THE MAJORITY OF THE MOISTURE/ENERGY WITH THIS SYSTEM STAYING TO
OUR NORTH. HOWEVER...HPC SOLN AS WELL AS THE ECMWF AND ITS
ENSEMBLES DO SUPPORT SHORTWAVE ENERGY PINWHEELING BEHIND THE
SYSTEM AND PIVOTING ACROSS THE REGION ON THURSDAY. PLUMES INDICATE
THIS WOULDN`T BE MUCH, BUT SOME SPOTTY SHRAS CAN`T BE RULED OUT
ACROSS NORTHERN/WESTERN SECTIONS ON THURSDAY. HAVE KEPT SLIGHT
CHC POPS (20%) IN PLACE AS A RESULT. OTHERWISE, EXPECT PARTLY
CLOUDY SKY EARLY GIVING WAY TO AFTN/EVENING CLEARING.
FOR TEMPERATURES, LOWS WED NIGHT IN THE 30S TO ~40. FORECAST HIGH
THU IN THE M/U 40S NORTH TO LOW 50S SOUTH.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
ANOMALOUS UPR LVL TROUGH TO RMN OVR THE ERN CONUS THROUGH MUCH OF
THE EXTENDED PD. THE TROUGH FCST TO SHIFT E/JUST OFF THE CST BY ERY
NEXT WK. WILL CONT W/ DRY FCST...W/ TEMPS AVGG 5-10F BLO NRML AND
EACH DAY HAVING VRB CLDNS/PCLDY NGTS. HI TEMPS RANGING THROUGH THE
40S. MOST LO TEMPS FM THE M/U20S TO L30S.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
A WARM FRONT CURRENTLY DRAPED ALONG THE CAROLINA COAST WILL
GRADUALLY LIFT INTO THE MID ATLANTIC REGION THIS AFTERNOON AS A
COMPLEX LOW PRESSURE SYSTEM APPROACHES THE AREA FROM THE SOUTHWEST
TODAY. OVERRUNNING PRECIPITATION AND LOWER CIGS ASSOCIATED WITH
THE WARM FRONT WILL SPREAD INTO THE MID ATLANTIC REGION FROM THE
SOUTHWEST THIS MORNING AND BEGIN TO IMPACT KRIC...KPHF...KORF...AND
KECG AFTER 26/1600Z. DURING THIS AFTERNOON...RAINFALL WILL BECOME
MODERATE TO HEAVY AT TIMES (LOWERING CIGS TWD 500 FT AGL) AND E-SE
WINDS WILL BECOME BREEZY WITH GUSTS AROUND 25-30 KT. KSBY WILL
BEGIN TO EXPERIENCE SIMILAR CONDITIONS AFTER 26/2000Z.
PRECIPITATION WILL COME TO AN END FROM SOUTHWEST TO NORTHEAST
THROUGH TUESDAY EVENING AS LOW PRESSURE MOVES NORTHEAST AND OUT OF
THE AREA AFTER MIDNIGHT. BREEZY WINDS OVERNIGHT WILL HELP TO SCOUR
OUT LOWER CIGS AND IMPROVE VISIBILITIES ONCE PRECIP COMES TO AN END.
&&
.MARINE...
SCA HEADLINES HAVE BEEN ADJUSTED TO BEGIN EARLY THIS MORNING WITH
THE EXCEPTION OF CURRITUCK SOUND AND NRN COASTAL WATERS WHERE
WINDS WILL NOT INCREASE UNTIL THIS AFTN. HAVE ALREADY BEGUN TO SEE
A SLIGHT INCREASE IN WINDS OVER THE SRN BAY AS HIGH PRESSURE NOW
RESIDES OVER NEW ENGLAND AND THE PRESSURE GRADIENT TIGHTENS IN
RESPONSE TO THE APPROACHING LOW PRESSURE SYSTEM TO THE SOUTHWEST.
EAST WINDS ARE GENERALLY AOB 15 KT...HOWEVER THEY WILL TURN SE
AND INCREASE THIS AFTN...GUSTING BTWN 25-40 KT (DEPENDING ON
LOCATION). SE WINDS WILL PEAK EARLY THIS EVENING...THEN BECOME SW
AND DECREASE AFTER MIDNIGHT TONIGHT. SEAS ARE GENERALLY 4-5 FT
EARLY THIS MORNING AND WILL ALSO INCREASE TO 7-10 FT DURING THE
AFTN AND OVERNIGHT AS LOW PRESSURE MOVES UP THE MID ATLANTIC
SEABOARD AND INTENSIFIES.
AS THE LOW MOVES NORTH OF AREA WATERS...WARM MARINE AIR CONTINUED
TO BE PULLED INTO THE STORM AND WILL ACT TO INHIBIT ADDITIONAL
MIXING IN THE WAKE OF THE LOW. AFTER THAT...A PROLONGED PERIOD OF
OFFSHORE WINDS PREVAILS WED THROUGH AT LEAST FRIDAY. WINDS WILL
INITIALLY BE WSW ON WED...THEN WNW THU INTO THE WEEKEND. THE
POTENTIAL FOR EXTENDED SCA FLAGS EXISTS DURING THIS TIME DUE TO A
LONG PERIOD OF LOW LEVEL CAA...RESULTING IN WIND SPEEDS AOA 20-25 KT
AT TIMES.
&&
.TIDES/COASTAL FLOODING...
TIDAL ANOMALIES ARE STILL RUNNING ABOUT 0.5 TO 1.0 FT ABOVE
NORMAL...ESPECIALLY DURING THE HIGH TIDE CYCLE TO OCCUR THIS
EVENING. OVERALL WATER LEVELS ARE EXPECTED TO STAY ABOUT 1-2 FT
BELOW MINOR FLOODING THRESHOLDS...BUT WILL NEED TO MONITOR LATEST
FORECASTS CLOSELY DUE TO INCREASING E-SE WINDS THIS AFTN AND
EVENING.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR ANZ635>638.
SMALL CRAFT ADVISORY UNTIL 10 AM EST WEDNESDAY FOR ANZ630>632-
634.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 1 AM EST WEDNESDAY FOR
ANZ633.
SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR ANZ650-
652-654.
GALE WARNING FROM 4 PM THIS AFTERNOON TO 1 AM EST WEDNESDAY
FOR ANZ650-652-654.
SMALL CRAFT ADVISORY UNTIL 1 AM EST THURSDAY FOR ANZ656.
SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR ANZ658.
&&
$$
SYNOPSIS...MAM
NEAR TERM...JDM/MAM
SHORT TERM...MAM
LONG TERM...ALB
AVIATION...BMD
MARINE...BMD
TIDES/COASTAL FLOODING...AKQ
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
413 AM EST TUE FEB 26 2013
.SYNOPSIS...
STRONG LOW PRESSURE WILL TRACK FROM THE LOWER TENNESSEE VALLEY TO
THE GREAT LAKES TODAY. A SECONDARY LOW DEVELOPING OVER THE
SOUTHERN APPALACHIANS IS EXPECTED TO PULLING A WARM FRONT UP INTO
THE REGION LATER TODAY...RESULTING IN WIDESPREAD RAINFALL. DRY
WEATHER RETURNS ON WEDNESDAY, WITH GRADUALLY COOLER CONDITIONS
FOR THE LATTER HALF OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST WATER VAPOR IMAGERY SHOWS STRONG UPPER LOW LOCATED OVER THE
LOWER MISSISSIPPI RVR VALLEY EARLY THIS MORNING. AT THE
SFC...POWERFUL AREA OF SFC LOW PRESSURE CONTINUES TO LIFT NE
ACROSS THE OZARKS/CENTRAL MS VLY, WITH A WELL-DEFINED WARM
CONVEYOR BELT EVIDENT ON IR/WV SAT IMAGERY SPREADING PCPN ACROSS
THE TN AND LOWER OH VLYS. FARTHER SOUTH, A WARM FRONT WAS ANALYZED
ALONG THE GULF COAST...EXTENDING NEWD ALONG THE SE COAST.
SECONDARY LOW PRESSURE WAS BEGINNING TO DEVELOP ACROSS THE GULF
COAST, WITH MSAS 3-HR PRESSURE FALLS ON THE ORDER OF 3-4MB OVER S
MS/GA. FINALLY, TO THE NORTH ~1024MB SFC HIGH PRESSURE HAS
RETREATED INTO THE NORTHEAST US, BUT CONTINUES TO NOSE DOWN THE
EAST COAST THIS MORNING.
INCREASING ISENTROPIC LIFT/SWLY FLOW WILL CONTINUE TO ADVECT
UPPER/MID LEVEL MOISTURE INTO THE REGION OVER THE NEXT FEW HOURS.
REGIONAL RADAR MOSAIC INDICATING PRECIP BREAKING OUT ACROSS
WESTERN CAROLINAS AT THIS HOUR, AND LIKELY NOT TO PUSH INTO FAR SW
CORNER OF AKQ CWA UNTIL AFTER SUNRISE. HAVE AGAIN LOWERED POP FOR
THE NEXT FEW HOURS, WITH HRRR DOING A GOOD JOB THUS FAR IN TIMING
PCPN SHIELD.
AS EXPECTED, DRY ANTECEDENT AIRMASS OVER THE AREA HAS MODIFIED
LITTLE OVER THE PAST FEW HOURS, WITH DEWPOINTS STILL IN THE TEENS
TO LOW 20S ACROSS OUR E VA PIEDMONT COUNTIES. THUS, PRECIP STILL
LKLY SEVERAL HRS OFF. AS PRECIP BREAKS OUT ACROSS THE REGION AFTER
SUNRISE EXPECT A BRIEF PERIOD OF SLEET TO MIX WITH RAIN ACROSS
OUR PIEDMONT COUNTIES. HOWEVER, AS SLUG OF OVERRUNNING MOISTURE
CONTINUES TO DRAW CLOSER AND DRIER AIR CONTINUES TO ERODE, EXPECT
DURATION OF ANY NON-LIQUID PCPN TO BE QUITE BRIEF.
FROM THERE, FORECAST DETAILS HAVE CHANGED VERY LITTLE FROM
PREVIOUS THINKING, WITH A GENERAL MODEL CONSENSUS CONTINUES TO
FAVOR TAKING THE SFC LOW FROM CURRENT POSITION OVER E AR JUST SE
OF KSTL INTO DOWNSTATE IL BY TONIGHT. MEANWHILE, SECONDARY SFC
LOW LOOKS TO SLIDE FROM THE CENTRAL GULF COAST ACROSS THE COASTAL
CAROLINAS. RAIN CHANCES RATCHET UP QUICKLY THIS MORNING INTO THE
AFTN AS WARM FRONT SLIPS NORTH AND VERY MOIST AIRMASS PUSHES INTO
THE AREA. STEADY RAIN LOOKS TO PUSH SW TO NE ACROSS THE AREA FROM
MID MORNING INTO THE EARLY EVENING, WITH RAIN ENDING FROM S TO N
AS WARM FRONT LIFTS NORTH OF THE AREA.
RAINFALL AMOUNTS WILL AVERAGE 0.75" TO 1.50" FOR THIS EVENT. NO
PROBLEMS EXPECTED WITH FLASH FLOOD GUIDANCE, SO NO HEADLINES
ANTICIPATED. SPC HAS AREA OUTLOOKED IN A `GENERAL THUNDER` AREA,
WITH SLIGHT RISK SHUNTED FARTHER SOUTHEAST. THIS JIVES WELL WITH
CURRENT THINKING AS IT APPEARS THAT WARM SECTOR REMAINS ORIENTED
JUST SOUTHEAST OF THE AREA ACROSS FAR SE NC AND POINTS SOUTH. NAM
REMAINS MOST BULLISH WITH MLCAPE. HOWEVER, EVEN THAT SOLUTION
RESULTING IN A MODESTLY UNSTABLE AIRMASS ALOFT, WITH THE BL LKLY
REMAINING STABLE THROUGHOUT.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
WEDNESDAY AND THURSDAY GENERALLY CHARACTERIZED BY DEVELOPING UPPER
TROUGH OVER THE EASTERN CONUS, RESULTING IN GRADUALLY COOLER
CONDITIONS FOR THE MID TO LATE WEEK PERIOD.
SFC LOW AND ASSOCIATED FRONTAL BOUNDARY LIFT NE INTO NEW ENGLAND
EARLY ON WED AS UPPER LOW LINGERS OVER THE OHIO VALLEY/EASTERN
GREAT LAKES. DEEP WSW FLOW IN PLACE WILL BRING A MILD AFTERNOON
WITH HIGH TEMPERATURES IN THE UPR 50S TO MID 60S UNDER A PARTLY
SUNNY SKY. THE UPPER LOW MOVES EAST THROUGH PA ON THURSDAY WITH
THE MAJORITY OF THE MOISTURE/ENERGY WITH THIS SYSTEM STAYING TO
OUR NORTH. HOWEVER...HPC SOLN AS WELL AS THE ECMWF AND ITS
ENSEMBLES DO SUPPORT SHORTWAVE ENERGY PINWHEELING BEHIND THE
SYSTEM AND PIVOTING ACROSS THE REGION ON THURSDAY. PLUMES INDICATE
THIS WOULDN`T BE MUCH, BUT SOME SPOTTY SHRAS CAN`T BE RULED OUT
ACROSS NORTHERN/WESTERN SECTIONS ON THURSDAY. HAVE KEPT SLIGHT
CHC POPS (20%) IN PLACE AS A RESULT. OTHERWISE, EXPECT PARTLY
CLOUDY SKY EARLY GIVING WAY TO AFTN/EVENING CLEARING.
FOR TEMPERATURES, LOWS WED NIGHT IN THE 30S TO ~40. FORECAST HIGH
THU IN THE M/U 40S NORTH TO LOW 50S SOUTH.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
ANOMALOUS UPR LVL TROUGH TO RMN OVR THE ERN CONUS THROUGH MUCH OF
THE EXTENDED PD. THE TROUGH FCST TO SHIFT E/JUST OFF THE CST BY ERY
NEXT WK. WILL CONT W/ DRY FCST...W/ TEMPS AVGG 5-10F BLO NRML AND
EACH DAY HAVING VRB CLDNS/PCLDY NGTS. HI TEMPS RANGING THROUGH THE
40S. MOST LO TEMPS FM THE M/U20S TO L30S.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
A WARM FRONT CURRENTLY DRAPED ALONG THE CAROLINA COAST WILL
GRADUALLY LIFT INTO THE MID ATLANTIC REGION THIS AFTERNOON AS A
COMPLEX LOW PRESSURE SYSTEM APPROACHES THE AREA FROM THE SOUTHWEST
TODAY. OVERRUNNING PRECIPITATION AND LOWER CIGS ASSOCIATED WITH
THE WARM FRONT WILL SPREAD INTO THE MID ATLANTIC REGION FROM THE
SOUTHWEST THIS MORNING AND BEGIN TO IMPACT KRIC...KPHF...KORF...AND
KECG AFTER 26/1600Z. DURING THIS AFTERNOON...RAINFALL WILL BECOME
MODERATE TO HEAVY AT TIMES (LOWERING CIGS TWD 500 FT AGL) AND E-SE
WINDS WILL BECOME BREEZY WITH GUSTS AROUND 25-30 KT. KSBY WILL
BEGIN TO EXPERIENCE SIMILAR CONDITIONS AFTER 26/2000Z.
PRECIPITATION WILL COME TO AN END FROM SOUTHWEST TO NORTHEAST
THROUGH TUESDAY EVENING AS LOW PRESSURE MOVES NORTHEAST AND OUT OF
THE AREA AFTER MIDNIGHT. BREEZY WINDS OVERNIGHT WILL HELP TO SCOUR
OUT LOWER CIGS AND IMPROVE VISIBILITIES ONCE PRECIP COMES TO AN END.
&&
.MARINE...
STARTED SCA NORTH OF PARRAMORE ISLAND WITH SEAS AROUND 5 FT AT
BUOY 09. THIS IS DUE TO SWELL. SCA NOW IN EFFECT OVER THE COASTAL
WATERS S OF VA/NC BORDER WILL EXTEND N TO PARRAMORE ISLAND BY 09Z
WHICH LINES UP WITH WAVEWATCH MODEL (3 HOURS EARLIER THAN PREVIOUS
FCST) . NO CHANGES MADE TO MARINE HEADLINES OVER THE BAY OR INLAND
WATERS.
PREVIOUS DISCUSSION...
WILL HANG ONTO SCA A LTL WHILE LONGER INVOF NE NC OCN WTRS (MAY
ACTUALLY HAVE TO KP IT UP THROUGH THE NGT...AND MERGE W/ CONDS
XPCD TUE INTO WED). OTRW...A LULL IN WINDS...AND SEAS/WAVES AS SFC
HI PRES HAS BECOME CNTRD OVR THE MDATLC STATES. THE CNTR OF THE HI
WILL SLOLY DRIFT NE INTO NEW ENG BY TUE...RESULTING IN INCRSD WIND
SPEEDS FM THE ESE AHD OF NEXT (COMPLEX/OCCLUDED) STORM SYS
APPROACHING FM THE W AND SW. MDL GUID RMNS CONSISTENT HIGHEST PD
FOR WIND SPEEDS I TUE EVE INTO ERY TUE NGT (ROUGHLY 21-23Z/26 TO
05-08Z/27) AHD OF SCNDRY LO PRES TRACKING NE ALG THE CSTL PLAIN.
DIRECTION WOULD BE ESE DURG HIGHEST WIND SPEEDS...THEN A SHIFT TO
THE SW OVRNGT TUE NGT (W/ SPDS LWRG) AS THE LO CONTS MOVING NNE TO
NR THE CNTRL NJ CST BY 12Z/27 (WED MRNG). AFT THAT...PROLONGED PD
OF OFFSHR WINDS... INITIALLY WSW ON WED...THEN WNW FM THU INTO THE
WKND...AND PTNTL FOR XTNDD PD OF SCAS ESP DUE TO LONG PD OF LO LVL
CAA AND SPDS AOA 20-25 KT AT TIMES.
HOISTING SCAS FOR ALL AREAS EITHER FM LT TNGT/TUE MRNG OR TUE
AFTN...AND LASTING INTO TUE NGT (ON THE OCN...INTO ERY WED).
ALSO...DUE TO PTNTL 35 KT GUSTS...GALE WARNING RAISED ON THE NRN 3
OCN ZONES (22Z/26-06Z/27).
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 1 AM EST WEDNESDAY FOR
ANZ630-631-633-635>638.
SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 5 AM EST
WEDNESDAY FOR ANZ632-634.
SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR ANZ654.
GALE WARNING FROM 5 PM THIS AFTERNOON TO 1 AM EST WEDNESDAY
FOR ANZ650-652-654.
SMALL CRAFT ADVISORY UNTIL 10 AM EST WEDNESDAY FOR ANZ656.
SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR ANZ650-
652.
SMALL CRAFT ADVISORY UNTIL 10 AM EST WEDNESDAY FOR ANZ658.
&&
$$
SYNOPSIS...MAM
NEAR TERM...JDM/MAM
SHORT TERM...MAM
LONG TERM...ALB
AVIATION...BMD
MARINE...BMD
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
325 AM EST TUE FEB 26 2013
.SYNOPSIS...
A COMPLEX LOW PRESSURE SYSTEM WILL ARRIVE LATER THIS MORNING...
MOVING ACROSS THE REGION OVER THE COURSE OF THE DAY. A SURFACE LOW
WILL SLIDE OVER THE AREA LATE TONIGHT...BRINGING MORE RAIN AND GUSTY
WINDS BEFORE MOVING OFF TO THE NORTHEAST WEDNESDAY MORNING. A
TROUGH OF LOW PRESSURE WILL FOLLOW AND WILL PASS SLOWLY EAST
ACROSS THE REGION WEDNESDAY NIGHT AND THURSDAY. FOR THE
WEEKEND...LOW PRESSURE WILL REMAIN OFF THE COAST WHILE HIGH
PRESSURE SLOWLY PUSHES IN FROM THE CENTRAL STATES.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
CLOUDS WILL CONTINUE TO THICKEN AND LOWER AS LOW PRESSURE BEGINS
TO MOVE IN.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
A LARGE AND STILL INTENSE LOW PRESSURE SYSTEM NOW MAKING ITS WAY
UP THE ERN SEABOARD. THE PARENT UPPER LOW DRIVING THE STORM SYSTEM
IS STILL BACK ACROSS THE CNTRL PLAINS...SPREADING HEAVY SNOW AND
BLIZZARD CONDITIONS FROM OK TO IL. THE OTHER SIDE OF THE STORM
LIES ACROSS THE DEEP SOUTH...SPREADING PLENTY OF PRECIP ACROSS THE
SRN STATES AND THIS BATCH WILL EVENTUALLY MOVE ACROSS OUR REGION.
WHILE THE PLAINS UPPER LOW CONTINUES TO SLOWLY DRIFT EWD...THE
LARGE GULF MOISTURE FETCH WILL BE DRIVEN UP THE ERN SEABOARD OVER
THE COURSE OF TODAY-TONIGHT.
THE MAIN ISSUE FOR ABOUT THE WRN HALF OF THE CWA IS THE SUB-FREEZING
OVERNIGHT TEMPS AND SOME COLD-AIR LOCKED INTO AREA MTN VLYS AS THE
PRECIP ARRIVES IN JUST A FEW HRS. CLEAR SKIES OVER THE PAST SEVERAL
HRS ALLOWED AREA TEMPS TO PLUMMET AFTER A RELATIVELY WARM AFTN. THE
CIRRUS DEBRIS FROM THE INCOMING WAVE OF PRECIP HAS ALREADY OVERTAKEN
MUCH OF THE AREA...WHICH WILL BASICALLY HOLD THESE TEMPS IN
PLACE...PREVENTING THEM FROM DROPPING MUCH FURTHER BUT ALSO KEEPING
THEM NEARLY STEADY IN THE 25-30 DEG RANGE AS PRECIP ARRIVES. ALSO
COMING IN FAST WILL BE A POTENT LOW LEVEL JET MAX...CARRYING WARMER
TEMPS RIDING OVER THE BOUNDARY LAYER. FALLING PRECIP WILL START OUT
AS A MIX OF RAIN...SLEET AND SOME SNOW ALONG THE LEADING EDGE OVER
MUCH OF THE AREA - BUT MAINLY WEST OF THE I-95 CORRIDOR.
PRECIP IS QUICKLY APPROACHING AND WILL ARRIVE OVER THE SWRN COUNTIES
OF THE CWA TOWARD DAWN...QUICKLY TRUDGING UP THE PIEDMONT/SHEN VLY
THRU THE REST OF THE MRNG HRS. NEAR-TERM GUIDANCE LIKE THE HRRR AND
VARIOUS LOCAL WRF GUIDANCE HAVE THE CWA COVERED IN PRECIP BY EARLY
AFTN...INCLUDING THE DC/BALT AREAS - BUT ALL RAIN BY THAT TIME FOR
THE I-95 CORRIDOR.
THE MAIN HAZARDS IN EFFECT FOR THE AREA ARE THE WINTRY PRECIP
POTENTIAL FOR AREAS ALONG AND W OF THE BLUE RIDGE AND THE HEIGHTENED
FLOODING POTENTIAL FOR MUCH OF THE METRO AREAS W/ THE LOWER FFG.
WHILE OTHER AREAS OF THE CWA COULD SEE HIGHER STORM-TOTAL RAINFALL
AMOUNTS...FFG IS MUCH LOWER ACROSS THE METROPOLITAN REGION AND WE`RE
STILL IN THE TIME OF YEAR WHERE THERE IS MORE RUNOFF THAN MOISTURE
SOAKED INTO THE SOIL. THE HIGHEST RAINFALL TOTALS FROM TODAY ARE
EXPECTED TO BE MAINLY ON THE LEE SIDE OF THE BLUE RIDGE. PERIODS OF
UPSLOPE AND TERRAIN INTERACTION RAINS BETWEEN THE RIDGE AND THE HWY
29 CORRIDOR COULD AMOUNT TO ACCUMULATED RAINFALL BETWEEN 1-1.5
INCHES W/ LOCALLY HIGHER AMOUNTS. MOST GUIDANCE MEMBERS ARE IN-SYNC
W/ AREA AVERAGES NEAR AN INCH BY LATE TONIGHT WHEN THE SYSTEM MOVES
AWAY FROM THE REGION.
CONCERNS FOR GOOD AMOUNTS OF ICE ACCRETION REMAIN ACROSS THE WRN
TIER OF THE CWA ALONG THE HIGHER TERRAIN AND TO A LESSER
EXTENT...NEARBY VLYS. AS W/ MOST ICING/COLD AIR DAMMING
EVENTS...TODAY WILL SEE A MIX OF RISING AND LOWERING LEVELS OF
ABOVE-FREEZING AIR IN THE BOUNDARY LAYER INTERACTING W/ THE APLCN
RIDGELINES. ACROSS THE SHEN VLY...THE BLUE RIDGE AND SURROUNDING
FOOTHILL REGIONS...BRIEF PERIODS OF FREEZING RAIN ARE EXPECTED AT
PRECIP ONSET AND TOWARD THE MID MRNG HRS. AS THE DAY PROGRESSES AND
TEMPS RISE SLOWLY OUT OF THE FROZEN REALM...MORE OF THE AREA WILL
RECEIVE ALL-RAIN AN HELP TO MELT ANY ICE THAT HAS FORMED.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
WEDNESDAY MORNING THE SECONDARY LOW WILL BE PULLING TO THE N OF THE
MASON DIXON LINE...LEAVING JUST THE LARGE 500MB CUTOFF OVER THE
MIDWEST. IN BETWEEN THE TWO...TEMPS ON SW FLOW WILL WARM INTO THE
50S AND LOWS 60S ACROSS THE FORECAST AREA ON WED.
LATER...THE CENTER OF THAT 500 MB LOW WILL SLIDE SLOWLY EAST OVER
SOUTHERN PA AND NORTHERN MD WED NIGHT INTO THURSDAY. WITH THE STEEP
LAPSE RATES ASSOC WITH THAT...THERE WILL BE SCATTERED SHOWERS AROUND
WED NIGHT INTO THU...LIKELY WILL BE A MIX OF RAIN AND SNOW SHOWERS
DEPENDING ON THE TIME OF DAY AND ELEVATION OF REPORT. PRECIP AMOUNTS
WILL BE LIGHT...AND WITH TEMPS STAYING ABOVE FREEZING THRU THE
TIME...IMPACT OF ANY SNOW SHOWERS SHOULD BE MINIMIZED.
AFTER THAT FOR THE END OF THE WEEK INTO EARLY NEXT WEEK...ANY PRECIP
SHOULD BE LIMITED TO MOUNTAIN SNOW SHOWERS. THE OPERATIONAL GFS HAS
A STRONGER UPPER LOW FORECAST OVER THE AREA ON SUNDAY...BUT IS
DISCOUNTED FOR NOW. AFTER WED...TEMPS WILL BE NEAR OR BELOW NORMAL
INTO EARLY NEXT WEEK.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
THE PIECE OF THE MUCH LARGER STORM SYSTEM THAT WILL MOVE ACROSS OUR
AREA WILL MAINLY BE A SEVERAL-HR PERIOD OF LIGHT-MODERATE RAINS.
GUSTY WINDS WILL BEGIN TO SPREAD ACROSS THE AREA TOWARD LATE
EVE...AS THE SFC LOW DRIFTS ACROSS THE REGION BUT MAINLY LIGHT WINDS
THRU THE REMAINDER OF THE MRNG. LIGHT PRECIP THAT STARTS AFTER DAWN
WILL BE A WINTRY MIX TOWARD THE KCHO REGION...AND TO A LESSER EXTENT
AS IT ARRIVES OVER THE DC/BALT AREA AIRPORTS. CIGS AND VSBYS WILL
LIKELY DROP TOWARD IFR LATER THIS AFTN/EVE AS THE HEAVIER RAIN
SHOWERS MOVE ACROSS THE REGION. AS PRECIP LETS-UP...SOLID IFR
CONDITIONS ARE EXPECTED TO LINGER INTO THE OVERNIGHT HRS AT LEAST
INTO THE PREDAWN HRS WED.
CONDITIONS WILL GRADUALLY IMPROVE BEGINNING WEDNESDAY MORNING AS LOW
PRESSURE SLOWLY PULLS AWAY TO THE NORTH AND EAST. SCATTERED RAIN AND
SNOW SHOWERS WILL BRING LOCALLY LOWER VSBYS AND CIGS WITH SHOWERS
WED NIGHT THRU THU. AREAS OF FOG COULD DEVELOP DURING THE OVERNIGHT
PERIODS WITH MOIST GROUND IN PLACE.
&&
.MARINE...
QUIET ON THE WATERS BUT ONLY FOR A FEW MORE HRS. AN INTENSE STORM
SYSTEM AFFECTING AREAS FROM THE PLAINS TO THE SOUTHEAST WILL SWEEP
ACROSS THE REGION TODAY. WINDS WILL PICK UP OUT OF THE EAST DURING
THE MID-LATE MRNG HRS. A SFC LOW COMING OUT OF THE CAROLINAS WILL
SLIDE UP TOWARD THE AREA LATER TODAY...BRINGING WIDESPREAD RAIN AND
GUSTY WINDS TO THE MARINE AREAS. NEAR-GALE GUSTS WILL BE POSSIBLE
LATE TONIGHT AS THE LOW MOVES OVER THE NRN CHESAPEAKE BAY. SMALL
CRAFT CONDITIONS WILL ARRIVE EARLIER IN THE DAY...BUT ALSO END
QUICKLY DURING THE OVERNIGHT HRS.
BREEZY CONDITIONS COULD DEVELOP ON THE BACKSIDE OF THE LOW THU AND
FRI. A SMALL CRAFT ADVISORY MAY BE NEEDED. WINDS ARE EXPECTED TO
REMAIN BELOW ADVISORY LEVELS FRIDAY NIGHT AND SATURDAY.
&&
.TIDES/COASTAL FLOODING...
LOPRES MVG THRU THE OHVLY TUE WL PROMOTE INCRSG E/SELY FLOW.
THEREFORE...WUD XPCT POS WATER ANOMOLIES TO INCR DURING THE DAY. A
SECONDARY AREA OF LOPRES WIL CROSS THE WATERS WED MRNG. HOWEVER...
WNDS DONT TURN W/NWLY TIL LATE DAY THU. THAT WUD SUGGEST THAT
WHATEVER EXCESS WATER IS DRIVEN INTO THE ESTUARY MAY BE THERE FOR A
WHILE.
IN SPITE OF A FULL MOON...ETSS MDL GDNC YIELDS WATER LVLS THAT
WOULDNT YIELD ADVY LVL WATER HGTS. THE 1ST TIDE OF CONSEQUENCE WOULD
BE THE WED MRNG TIDE CYCLE. THE TWO TIDES ASTRONOMICALLY ARE
PRACTICALLY THE SAME...SO THE SEMI-DIURNAL CYCLE WONT FACTOR
CONSIDERABLY THIS TIME.
ESTOFS...CBOFS AND HEC-RAS GDNC SOLNS DO RESULT IN MINOR FLOODING...
EITHER BEGINNING WED MRNG /CBOFS/ OR TUE NGT /ESTOFS FOR THE WRN
SHORE OF THE CHSPK BAY AS WELL AS HEC-RAS AT WASD2/. BASED ON THE
PTTN...THESE RESULTS SEEM MORE REALISTIC. SINCE WE/RE AT LEAST 24
HRS OUT...WL CONT HAZARDOUS WEATHER OUTLOOK WORDING AT THIS TIME.
WOULD BE MINDFUL OF BOTH TIDE CYCLES FOR STARTERS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH THIS EVENING
FOR DCZ001.
MD...WINTER STORM WARNING FROM 7 AM THIS MORNING TO MIDNIGHT EST
TONIGHT FOR MDZ501.
FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH THIS EVENING
FOR MDZ004>006-009>011-013-014.
WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 6 PM EST
THIS EVENING FOR MDZ003-502.
VA...WINTER STORM WARNING FROM 7 AM THIS MORNING TO MIDNIGHT EST
TONIGHT FOR VAZ503-504.
FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH THIS EVENING
FOR VAZ042-053-054-501.
WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 6 PM EST
THIS EVENING FOR VAZ025>031-036>040.
WV...WINTER STORM WARNING FROM 7 AM THIS MORNING TO MIDNIGHT EST
TONIGHT FOR WVZ501-503-505-506.
WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 6 PM EST
THIS EVENING FOR WVZ050>053-055-502-504.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 6 AM EST
WEDNESDAY FOR ANZ530>543.
&&
$$
SYNOPSIS...CAS/GMS
NEAR TERM...CAS
SHORT TERM...GMS
LONG TERM...CAS
AVIATION...CAS/GMS
MARINE...CAS/GMS
TIDES/COASTAL FLOODING...GMS/HTS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
715 PM EST WED FEB 27 2013
.UPDATE...
ISSUED AT 714 PM EST WED FEB 27 2013
DECIDED TO GO WITH AN ADVISORY FOR MARQUETTE COUNTY. LOOKING AT
PRESENT RADAR TRENDS...MORE ENHANCEMENT IS OCCURRING TO THE EAST OF
THE AREA AND IS HEADED THIS WAY. INTENSITY OF THE SNOW WITH UPSLOPE
FLOW HAS INCREASED ACROSS MARQUETTE COUNTY AS WELL AND HAD A REPORT
EARLIER AT 630 OF 3 INCHES OF SNOW IN HARVEY. NOT OUT OF THE
QUESTION THAT SOME AREAS COULD SEE 5 INCHES OF SNOW BEFORE THIS IS
ALL OVER. SYSTEM MOISTURE WILL PULL OUT AFTER MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 426 PM EST WED FEB 27 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A BROAD MID LEVEL LOW
CIRCULATION OVER THE GREAT LAKES/OHIO VALLEY. AT THE SFC...A
WEAKENING LOW PRES CENTER WAS LOCATED NEAR FLINT. SYSTEM ENDED UP
SLIGHTLY FARTHER N THAN EXPECTED YESTERDAY...AND THUS THE ASSOCIATED
WEAKENING SNOW SHIELD WAS ABLE TO SPREAD FARTHER N AND W INTO UPPER
MI TODAY...AIDED BY A SHORTWAVE THAT PIVOTED AROUND THE LARGE MID
LEVEL LOW CIRCULATION. THE NW EDGE OF THE -SN HAS SPREAD TO ABOUT A
BIG BAY/CHAMPION/CRYSTAL FALLS LINE. SNOW ACCUMULATIONS HAVE
GENERALLY BEEN 1 INCH OR LESS THOUGH SOME 2-3 INCH AMOUNTS WERE
OBSERVED ACROSS MENOMINEE/DELTA/SRN SCHOOLCRAFT COUNTIES. SINCE THE
WEAKENING SHORTWAVE AND ASSOCIATED DEEP LAYER FORCING ASSOCIATED
WITH THE HEAVIER SNOW HAS ROTATED TO THE SW...-SN HAS BEEN
DIMINISHING IN AREAL COVERAGE FROM LATE MORNING THRU THE AFTN. AS
EXPECTED...THERE HAS NOT BEEN ANY EVIDENCE OF LES TODAY DESPITE
CYCLONIC NE FLOW AS AIR MASS HAS BEEN TOO WARM. IN FACT...ON VIS
SATELLITE IMAGERY...HIGH CLOUDS ARE AT TIMES THIN ENOUGH TO REVEAL
LITTLE IF ANY LAKE EFFECT CLOUDS OVER LAKE SUPERIOR. THE SNOW THAT
HAS RECENTLY INCREASED INTO NCNTRL UPPER MI APPEARS MOSTLY RELATED
TO A LONG ARC OF ISENTROPIC ASCENT EXTENDING W FROM NEW ENGLAND...
BUT IT CERTAINLY LOOKS LIKE THERE MAY NOW BE A LAKE COMPONENT TO
THIS HEAVIER SNOW THAT HAS DEVELOPED.
IN THE SHORT TERM...FOCUS SHIFTS FROM REMNANT -SN ASSOCIATED WITH
SLOWLY DEPARTING GREAT LAKES/OHIO VALLEY MID LEVEL LOW TO POTENTIAL
OF LES OFF LAKE SUPERIOR. WITH NO ADDITIONAL SHORTWAVES EVIDENT
PIVOTING TOWARD UPPER MI AND WITH MODELS INDICATING INCREASING DEEP
LAYER QVECTOR CONVERGENCE WITH TIME...EXPECT LINGERING AREAS OF -SN
OVER ROUGHLY THE E HALF OF UPPER MI TO CONTINUE TO DIMINISH TONIGHT.
ANY ADDITIONAL SNOW ACCUMULATION WILL BE LESS THAN 1 INCH.
ATTENTION THEN TURNS TO POTENTIAL LES OFF LAKE SUPERIOR. HIGHER RES
MODEL GUIDANCE CONTINUES TO POINT TOWARD LES/UPSLOPE ENHANCED SNOW
TONIGHT. ALTHOUGH DEEPER MOISTURE/SATURATION AND SYNOPTIC -SN IS
SPREADING OUT OVER ERN LAKE SUPERIOR...HAVE DOUBTS ON THE INSISTENCE
OF HIGH RES GUIDANCE TO OUTPUT IN WHAT SOME CASES ARE SIGNIFICANT
PCPN TOTALS TONIGHT (REGIONAL GEM SHOWS AROUND 0.5 INCHES OF PCPN
TONIGHT OVER THE HIGHER TERRAIN OF MARQUETTE COUNTY...LOCAL HIGH
RESWRF 0.3-0.4...06Z NAM SHOWED UPWARDS OF 1 INCH BUT 12Z NAM AT
LEAST TRENDED DOWN TO WHAT SHOULD BE A MORE REASONABLE 0.2-0.3).
850MB TEMPS OF ONLY -6 TO -9C ACROSS LAKE SUPERIOR WILL NOT BE
SUFFICIENT FOR LES. SO...ONCE THE ISENTROPIC ASCENT CURRENTLY AIDING
THE SNOW INTO NCNTRL UPPER MI FALLS APART TONIGHT...EXPECT THE SNOW
TO DIMINISH SIGNIFICANTLY. WILL THUS CARRY HIGH POPS INTO NCNTRL
UPPER MI THIS EVENING...THEN DIMINISH PCPN TO JUST SCT -SHSN
OVERNIGHT. EXPECT A FEW INCHES OF SNOW ACCUMULATION THRU THE EVENING
ACROSS THE HIGHER TERRAIN OF THE NCNTRL (MARQUETTE COUNTY IN
PARTICULAR). IF THE ONGOING SNOW SHOWS SIGNS OF PERSISTENCE AND
LITTLE MOVEMENT (HEAVIEST SNOW IS CURRENTLY OCCURRING FROM
MARQUETTE/HARVEY WSW TO ISHPEMING/GWINN) WILL LIKELY NEED TO HOIST
AN ADVY. FARTHER W...LACKING SYNOPTIC FORCING...NOTHING MORE THAN
DEVELOPING CHC POPS/SCT -SHSN APPEAR REASONABLE.
850MB TEMPS FALL ANOTHER DEGREE OR TWO THU...BUT EVEN THAT WILL
STILL NOT BE QUITE COLD ENOUGH FOR LES. WITH ANY DEEPER MOISTURE
EXITING AND SINCE THERE WILL PROBABLY BE SOME NEGATIVE IMPACT DUE TO
DAYTIME HEATING WITH HIGHER SUN ANGLE AT THIS TIME OF YEAR...SCT
-SHSN OFF THE LAKE SHOULD WIND DOWN DURING THE DAY.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 426 PM EST WED FEB 27 2013
PREFERRED THE 00Z/27 ECMWF AND GLOBAL GEM OVER THE 12Z/27 GFS FOR
THE ENTIRE LONG TERM SINCE THE GFS HAS DISPLAYED POOR RUN TO RUN
CONTINUITY AND LACKS AGREEMENT WITH OTHER MODELS.
KEPT DIMINISHING CHANCES OF LAKE EFFECT SNOW THU NIGHT INTO EARLY
FRI IN AREAS FAVORED BY NE LOW LEVEL WINDS...BUT PUSHED BACK WHEN
POPS GO AWAY ENTIRELY BY AROUND 3 HOURS TO 18Z FRI. AFTER
THAT...VERY DRY LOW LEVELS ASSOCIATED WITH A SFC AND 500MB RIDGE
PUSHING INTO THE CWA. LOW LEVEL FLOW WILL CONTINUE TO BE OUT OF THE
N/NE UNTIL THE SFC RIDGE AXIS COMPLETELY PASSES SUN NIGHT WITH
SLIGHTLY COLDER 850MB TEMPS...SO WILL KEEP INCREASED CLOUD COVER NEAR
LAKE SUPERIOR. MAY SEE A BRIEF RETURN OF NE FLOW LES LATE FRI NIGHT
WITH THE PASSAGE OF A 500MB TROUGH...BUT ANY ACCUMULATIONS WILL BE
MINOR.
THE STORY FOR SUN THROUGH NEXT WED IS THAT A 500MB LOW WILL MOVE
OVER THE CWA THROUGH TUE BEFORE MOVE S ON WED. AT THE SAME
TIME...INCREASINGLY STRONG SFC RIDGING WILL MOVE INTO THE CWA...SO
PRECIP WILL BE AT A MINIMUM. PRECIP...IF ANY...WILL BE MINOR SO
SLIGHT CHANCE POPS AT BEST SEEM APPROPRIATE.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 612 PM EST WED FEB 27 2013
GUSTY N/NE WINDS WILL BE THE RULE AT KIWD/KCMX/KSAW THRU THIS FCST
PERIOD AS TIGHT PRES GRADIENT REMAINS IN PLACE ACROSS THE UPPER
GREAT LAKES. WIND DIRECTION IS MOST FAVORABLE FOR ENHANCED WINDS AT
KSAW...AND GUSTS THERE SHOULD BE IN THE 20-30KT RANGE THROUGHOUT THE
FCST PERIOD. AT KIWD...UPSLOPE N/NNE WINDS WILL LIKELY KEEP LOW MVFR
CIGS IN PLACE THRU THE FCST PERIOD. AS AIR MASS COOLS SLIGHTLY...
LAKE EFFECT -SHSN MAY GET UNDERWAY TONIGHT...BUT EXPECTATION IS FOR
ANY SHSN TO BE LIGHT AND NOT SIGNIFICANTLY REDUCE VIS. AT KCMX...
MVFR CIGS AT KCMX WILL CONTINUE. MAY SEE A FEW FLURRIES LATER
TONIGHT AT KCMX. AT KSAW...IDEAL UPSLOPE FLOW AND PERIODS OF -SN
SHOULD RESULT IN IFR CONDITIONS PREVAILING FOR THE NEXT SEVERAL HRS.
SOME IMPROVEMENT TO LOW MVFR SHOULD OCCUR LATE THIS EVENING WITH LOW
MVFR CONDITIONS CONTINUING THRU THE PERIOD UNDER UPSLOPE NORTHERLY
FLOW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 426 PM EST WED FEB 27 2013
TIGHT PRES GRADIENT BTWN HIGH PRES TO THE N AND NW AND LOW PRES
TRACKING THRU THE LWR LAKES WILL RESULT IN NORTHEASTERLY WINDS OF
20-30KT ACROSS LAKE SUPERIOR THRU THU. GALE FORCE GUSTS SHOULD BE
FREQUENT ENOUGH TO MAINTAIN GALE WARNING FOR THE E HALF OF LAKE
SUPERIOR. IN ADVANCE OF HIGH PRES RIDGE BUILDING TOWARD THE AREA
FRI...TIGHT PRES GRADIENT WILL REMAIN...RESULTING IN CONTINUED
20-30KT NE WINDS. THE STRONG WINDS/HIGH WAVES AND INFLUX OF COLDER
AIR WILL RESULT IN FREEZING SPRAY DEVELOPING TONIGHT AND CONTINUING
THRU FRI NIGHT. HVY FREEZING SPRAY MAY OCCUR FOR A TIME THU
NIGHT/FRI MORNING. WINDS WILL THEN DIMINISH FROM W TO E FRI NIGHT AS
HIGH PRES RIDGE MOVES CLOSER. ON SAT...WINDS SHOULD BE BLO 20KT
ACROSS THE ENTIRE LAKE. LIGHT WINDS...MOSTLY 10KT OR LESS...ARE
EXPECTED SUN/MON AS SFC HIGH PRES RIDGE WILL EXTEND FROM HUDSON BAY
S ACROSS THE UPPER LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 1 AM EST THURSDAY FOR MIZ005.
LAKE SUPERIOR...
GALE WARNING UNTIL 10 AM EST THURSDAY FOR LSZ244-245-248>250-
264>267.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...07
SHORT TERM...ROLFSON
LONG TERM...TITUS
AVIATION...07
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
612 PM EST WED FEB 27 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 426 PM EST WED FEB 27 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A BROAD MID LEVEL LOW
CIRCULATION OVER THE GREAT LAKES/OHIO VALLEY. AT THE SFC...A
WEAKENING LOW PRES CENTER WAS LOCATED NEAR FLINT. SYSTEM ENDED UP
SLIGHTLY FARTHER N THAN EXPECTED YESTERDAY...AND THUS THE ASSOCIATED
WEAKENING SNOW SHIELD WAS ABLE TO SPREAD FARTHER N AND W INTO UPPER
MI TODAY...AIDED BY A SHORTWAVE THAT PIVOTED AROUND THE LARGE MID
LEVEL LOW CIRCULATION. THE NW EDGE OF THE -SN HAS SPREAD TO ABOUT A
BIG BAY/CHAMPION/CRYSTAL FALLS LINE. SNOW ACCUMULATIONS HAVE
GENERALLY BEEN 1 INCH OR LESS THOUGH SOME 2-3 INCH AMOUNTS WERE
OBSERVED ACROSS MENOMINEE/DELTA/SRN SCHOOLCRAFT COUNTIES. SINCE THE
WEAKENING SHORTWAVE AND ASSOCIATED DEEP LAYER FORCING ASSOCIATED
WITH THE HEAVIER SNOW HAS ROTATED TO THE SW...-SN HAS BEEN
DIMINISHING IN AREAL COVERAGE FROM LATE MORNING THRU THE AFTN. AS
EXPECTED...THERE HAS NOT BEEN ANY EVIDENCE OF LES TODAY DESPITE
CYCLONIC NE FLOW AS AIR MASS HAS BEEN TOO WARM. IN FACT...ON VIS
SATELLITE IMAGERY...HIGH CLOUDS ARE AT TIMES THIN ENOUGH TO REVEAL
LITTLE IF ANY LAKE EFFECT CLOUDS OVER LAKE SUPERIOR. THE SNOW THAT
HAS RECENTLY INCREASED INTO NCNTRL UPPER MI APPEARS MOSTLY RELATED
TO A LONG ARC OF ISENTROPIC ASCENT EXTENDING W FROM NEW ENGLAND...
BUT IT CERTAINLY LOOKS LIKE THERE MAY NOW BE A LAKE COMPONENT TO
THIS HEAVIER SNOW THAT HAS DEVELOPED.
IN THE SHORT TERM...FOCUS SHIFTS FROM REMNANT -SN ASSOCIATED WITH
SLOWLY DEPARTING GREAT LAKES/OHIO VALLEY MID LEVEL LOW TO POTENTIAL
OF LES OFF LAKE SUPERIOR. WITH NO ADDITIONAL SHORTWAVES EVIDENT
PIVOTING TOWARD UPPER MI AND WITH MODELS INDICATING INCREASING DEEP
LAYER QVECTOR CONVERGENCE WITH TIME...EXPECT LINGERING AREAS OF -SN
OVER ROUGHLY THE E HALF OF UPPER MI TO CONTINUE TO DIMINISH TONIGHT.
ANY ADDITIONAL SNOW ACCUMULATION WILL BE LESS THAN 1 INCH.
ATTENTION THEN TURNS TO POTENTIAL LES OFF LAKE SUPERIOR. HIGHER RES
MODEL GUIDANCE CONTINUES TO POINT TOWARD LES/UPSLOPE ENHANCED SNOW
TONIGHT. ALTHOUGH DEEPER MOISTURE/SATURATION AND SYNOPTIC -SN IS
SPREADING OUT OVER ERN LAKE SUPERIOR...HAVE DOUBTS ON THE INSISTENCE
OF HIGH RES GUIDANCE TO OUTPUT IN WHAT SOME CASES ARE SIGNIFICANT
PCPN TOTALS TONIGHT (REGIONAL GEM SHOWS AROUND 0.5 INCHES OF PCPN
TONIGHT OVER THE HIGHER TERRAIN OF MARQUETTE COUNTY...LOCAL HIGH
RESWRF 0.3-0.4...06Z NAM SHOWED UPWARDS OF 1 INCH BUT 12Z NAM AT
LEAST TRENDED DOWN TO WHAT SHOULD BE A MORE REASONABLE 0.2-0.3).
850MB TEMPS OF ONLY -6 TO -9C ACROSS LAKE SUPERIOR WILL NOT BE
SUFFICIENT FOR LES. SO...ONCE THE ISENTROPIC ASCENT CURRENTLY AIDING
THE SNOW INTO NCNTRL UPPER MI FALLS APART TONIGHT...EXPECT THE SNOW
TO DIMINISH SIGNIFICANTLY. WILL THUS CARRY HIGH POPS INTO NCNTRL
UPPER MI THIS EVENING...THEN DIMINISH PCPN TO JUST SCT -SHSN
OVERNIGHT. EXPECT A FEW INCHES OF SNOW ACCUMULATION THRU THE EVENING
ACROSS THE HIGHER TERRAIN OF THE NCNTRL (MARQUETTE COUNTY IN
PARTICULAR). IF THE ONGOING SNOW SHOWS SIGNS OF PERSISTENCE AND
LITTLE MOVEMENT (HEAVIEST SNOW IS CURRENTLY OCCURRING FROM
MARQUETTE/HARVEY WSW TO ISHPEMING/GWINN) WILL LIKELY NEED TO HOIST
AN ADVY. FARTHER W...LACKING SYNOPTIC FORCING...NOTHING MORE THAN
DEVELOPING CHC POPS/SCT -SHSN APPEAR REASONABLE.
850MB TEMPS FALL ANOTHER DEGREE OR TWO THU...BUT EVEN THAT WILL
STILL NOT BE QUITE COLD ENOUGH FOR LES. WITH ANY DEEPER MOISTURE
EXITING AND SINCE THERE WILL PROBABLY BE SOME NEGATIVE IMPACT DUE TO
DAYTIME HEATING WITH HIGHER SUN ANGLE AT THIS TIME OF YEAR...SCT
-SHSN OFF THE LAKE SHOULD WIND DOWN DURING THE DAY.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 426 PM EST WED FEB 27 2013
PREFERRED THE 00Z/27 ECMWF AND GLOBAL GEM OVER THE 12Z/27 GFS FOR
THE ENTIRE LONG TERM SINCE THE GFS HAS DISPLAYED POOR RUN TO RUN
CONTINUITY AND LACKS AGREEMENT WITH OTHER MODELS.
KEPT DIMINISHING CHANCES OF LAKE EFFECT SNOW THU NIGHT INTO EARLY
FRI IN AREAS FAVORED BY NE LOW LEVEL WINDS...BUT PUSHED BACK WHEN
POPS GO AWAY ENTIRELY BY AROUND 3 HOURS TO 18Z FRI. AFTER
THAT...VERY DRY LOW LEVELS ASSOCIATED WITH A SFC AND 500MB RIDGE
PUSHING INTO THE CWA. LOW LEVEL FLOW WILL CONTINUE TO BE OUT OF THE
N/NE UNTIL THE SFC RIDGE AXIS COMPLETELY PASSES SUN NIGHT WITH
SLIGHTLY COLDER 850MB TEMPS...SO WILL KEEP INCREASED CLOUD COVER NEAR
LAKE SUPERIOR. MAY SEE A BRIEF RETURN OF NE FLOW LES LATE FRI NIGHT
WITH THE PASSAGE OF A 500MB TROUGH...BUT ANY ACCUMULATIONS WILL BE
MINOR.
THE STORY FOR SUN THROUGH NEXT WED IS THAT A 500MB LOW WILL MOVE
OVER THE CWA THROUGH TUE BEFORE MOVE S ON WED. AT THE SAME
TIME...INCREASINGLY STRONG SFC RIDGING WILL MOVE INTO THE CWA...SO
PRECIP WILL BE AT A MINIMUM. PRECIP...IF ANY...WILL BE MINOR SO
SLIGHT CHANCE POPS AT BEST SEEM APPROPRIATE.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 612 PM EST WED FEB 27 2013
GUSTY N/NE WINDS WILL BE THE RULE AT KIWD/KCMX/KSAW THRU THIS FCST
PERIOD AS TIGHT PRES GRADIENT REMAINS IN PLACE ACROSS THE UPPER
GREAT LAKES. WIND DIRECTION IS MOST FAVORABLE FOR ENHANCED WINDS AT
KSAW...AND GUSTS THERE SHOULD BE IN THE 20-30KT RANGE THROUGHOUT THE
FCST PERIOD. AT KIWD...UPSLOPE N/NNE WINDS WILL LIKELY KEEP LOW MVFR
CIGS IN PLACE THRU THE FCST PERIOD. AS AIR MASS COOLS SLIGHTLY...
LAKE EFFECT -SHSN MAY GET UNDERWAY TONIGHT...BUT EXPECTATION IS FOR
ANY SHSN TO BE LIGHT AND NOT SIGNIFICANTLY REDUCE VIS. AT KCMX...
MVFR CIGS AT KCMX WILL CONTINUE. MAY SEE A FEW FLURRIES LATER
TONIGHT AT KCMX. AT KSAW...IDEAL UPSLOPE FLOW AND PERIODS OF -SN
SHOULD RESULT IN IFR CONDITIONS PREVAILING FOR THE NEXT SEVERAL HRS.
SOME IMPROVEMENT TO LOW MVFR SHOULD OCCUR LATE THIS EVENING WITH LOW
MVFR CONDITIONS CONTINUING THRU THE PERIOD UNDER UPSLOPE NORTHERLY
FLOW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 426 PM EST WED FEB 27 2013
TIGHT PRES GRADIENT BTWN HIGH PRES TO THE N AND NW AND LOW PRES
TRACKING THRU THE LWR LAKES WILL RESULT IN NORTHEASTERLY WINDS OF
20-30KT ACROSS LAKE SUPERIOR THRU THU. GALE FORCE GUSTS SHOULD BE
FREQUENT ENOUGH TO MAINTAIN GALE WARNING FOR THE E HALF OF LAKE
SUPERIOR. IN ADVANCE OF HIGH PRES RIDGE BUILDING TOWARD THE AREA
FRI...TIGHT PRES GRADIENT WILL REMAIN...RESULTING IN CONTINUED
20-30KT NE WINDS. THE STRONG WINDS/HIGH WAVES AND INFLUX OF COLDER
AIR WILL RESULT IN FREEZING SPRAY DEVELOPING TONIGHT AND CONTINUING
THRU FRI NIGHT. HVY FREEZING SPRAY MAY OCCUR FOR A TIME THU
NIGHT/FRI MORNING. WINDS WILL THEN DIMINISH FROM W TO E FRI NIGHT AS
HIGH PRES RIDGE MOVES CLOSER. ON SAT...WINDS SHOULD BE BLO 20KT
ACROSS THE ENTIRE LAKE. LIGHT WINDS...MOSTLY 10KT OR LESS...ARE
EXPECTED SUN/MON AS SFC HIGH PRES RIDGE WILL EXTEND FROM HUDSON BAY
S ACROSS THE UPPER LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING UNTIL 10 AM EST THURSDAY FOR LSZ244-245-248>250-
264>267.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...TITUS
AVIATION...07
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
429 PM EST TUE FEB 26 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 428 PM EST TUE FEB 26 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW PRONOUNCED SPLIT FLOW
CONTINUING ACROSS NAMERICA. IN WHAT HAS BEEN A VERY ACTIVE SRN
STREAM RECENTLY...A WELL-DEFINED MID LEVEL LOW IS MOVING ENE INTO
THE LWR OHIO VALLEY. SRN STREAM RIDGING AHEAD OF FEATURE EXTENDS
FROM JUST OFF THE SE COAST TO SRN NEW ENGLAND AND THEN BACK INTO THE
UPPER LAKES. WITH NRN STREAM WELL N OF HERE...ARCTIC AIR HAS
RETREATED INTO NRN CANADA. CLOSER TO HOME...PESKY STRATOCU HAS
CONTINUED TO PLAGUE UPPER MI TODAY. HOWEVER...ROUGHLY THE W THIRD OF
THE FCST AREA HAS ENJOYED MOSTLY SUNNY SKIES FOR AT LEAST A PORTION
OF THE DAY. THE POCKET OF MOSTLY SUNNY SKIES CURRENTLY OVER THE W IS
SHOWING SIGNS OF EXPANDING EASTWARD AS STRONGER DAYTIME HEATING
UNDER HIGHER LATE FEB SUN ANGLE IS WORKING ON LOWER ALBEDO FORESTED
TERRAIN TO RAISE MIXED LAYER AND THUS MIX OUT THE SHALLOW MOIST
LAYER.
DURING THE SHORT TERM...MAIN FCST ISSUE WILL REVOLVE AROUND
NORTHWARD PROGESS OF A WEAKENING PCPN SHIELD SPREADING N AROUND SRN
STREAM MID LEVEL LOW AS IT TRACKS INTO THE UPPER OHIO VALLEY/LWR
LAKES REGION. EARLY ON...LOW CLOUDS WILL CONTINUE TO PRESENT SOME
ISSUES. CLEARING MAY CONTINUE TO EXPAND E FROM WRN UPPER MI OVER THE
NEXT COUPLE OF HRS...BUT WITH LOSS OF DAYTIME HEATING...STRATOCU
WILL PROBABLY TEND TO SPREAD BACK INTO THE AREAS THAT HAVE
CLEARED...ESPECIALLY IF THE STRATOCU TO THE E AND NE DOES NOT BREAK
UP DURING THE LATE AFTN/EVENING. LATEST VIS SATELLITE IMAGERY DOES
SHOW STRATOCU THINNING OVER ERN LAKE SUPERIOR...SO THERE MAY YET BE
SOME MORE CLEARING DURING THE EVENING. WILL BE A TREND TO MONITOR.
WHILE CLOUDS WILL AGAIN MAKE OR BREAK TEMP FCST...THERE WILL LIKELY
NOT BE AS GREAT OF A TEMP SPREAD TONIGHT AS IN PREVIOUS NIGHTS BTWN
AREAS WITH CLOUDS AND AREAS WITH LESS CLOUD SINCE INCREASING
GRADIENT WINDS WILL LIMIT RADIATIONAL COOLING. TRENDED TEMPS TOWARD
RAW MODEL GUIDANCE WHICH PUTS MIN TEMPS GENERALLY IN THE MID/UPPER
20S.
AS FOR PCPN...THE STRONG ISENTROPIC ASCENT COMPONENT TO PCPN SHIELD
SPREADING N INTO SRN WI/SRN MI ATTM WILL GRADUALLY FADE WITH TIME AS
THE ZONE OF STRONG ASCENT TRANSLATES EASTWARD...RESULTING IN ZONE OF
HEAVIEST PCPN SHIFTING E TOWARD THE LWR LAKES/SRN NEW ENGLAND
TONIGHT/WED MORNING. THUS...A DECAYING SHIELD OF PCPN WILL BE
LIFTING TOWARD UPPER MI TONIGHT/WED MORNING. RECENT MODEL TRENDS
GENERALLY POINT TOWARD A MORE AGGRESSIVE PUSH OF LIGHT SNOW INTO
UPPER MI. GIVEN THE STRONG NORTHWARD PUSH OF PCPN THRU LWR MI ATTM
AND THE LACK OF A LAYER OF VERY DRY AIR AT THE LOWER LEVELS TO THE N
ACROSS UPPER MI...HAVE OPTED TO TREND PCPN CHC SLIGHTLY FARTHER N
THAN PREVIOUS FCST TO ROUGHLY A KERY/KSAW/KIMT LINE AND RAISED POPS
TO HIGH CHC ALONG LAKE MI. WITH 850MB TEMPS NO LWR THAN -8/-9C...
IT`S VERY UNLIKELY THAT ANY LES WILL DEVELOP OFF LAKE SUPERIOR UNDER
STRONG NE CYCLONIC FLOW WED. IF SHIELD OF LIGHT SYNOPTIC SNOW DOES
REACH LAKE SUPERIOR...THEN A LITTLE LAKE COMPONENT WILL BE THERE.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 428 PM EST TUE FEB 26 2013
LITTLE CHANGES TO THE LONG TERM FROM 24 HOURS AGO...WITH THE
MAIN ITEM OF DIFFERENCE A SLIGHT WOBBLE TO THE NORTHWEST WITH THE
SYSTEM CURRENTLY MOVING THROUGH THE MID MISSISSIPPI VALLEY THAT
WILL MOVE THROUGH THE LOWER GREAT LAKES. THIS SLIGHT
ADJUSTMENT...PUSHES THE PRECIPITATION A TOUCH FARTHER INLAND FROM
LAKE MICHIGAN. BUT AS THE LONG TERM PERIOD BEGINS...THE LOW WILL
START IT/S EASTWARD SHIFT TOWARDS NEW YORK AND DIMINISH THE SNOW
ALONG THE LAKE MICHIGAN SHORELINE.
ATTENTION THEN TURNS TO THE AMOUNT OF MOISTURE AND COLD AIR IN THE
LOWER LEVELS TO SUPPORT LAKE ENHANCED AND UPSLOPE SNOW SHOWERS.
LATEST TRENDS IN THE MOISTURE AND COLD AIR /850MB TEMPERATURES
FALLING FROM -9C AT WEDNESDAY NIGHT TO -13C BETWEEN 900-850MB BY
THURSDAY AFTERNOON/ LEADS TO GREATER CONFIDENCE IN SCATTERED SNOW
SHOWERS OCCURRING FOR LOCATIONS NEAR LAKE SUPERIOR FROM PICTURED
ROCKS AND WESTWARD. INVERSION HEIGHTS AROUND 3-4KFT SHOULD KEEP THE
INTENSITY IN CHECK AND HELPS KEEP LAKE INDUCED CAPES BELOW 200
J/KG. THUS...WILL BUMP POPS UP 5-10 PERCENT INTO HIGHER END CHANCE
CATEGORY. SNOWFALL AMOUNTS SHOULD BE FAIRLY LIGHT...SINCE CLOUD
DEPTH IS FAIRLY LIMITED. WITH THE INITIAL CLOUD LAYER MAINLY BEING
BELOW THE DGZ WEDNESDAY NIGHT...WOULD EXPECT FLAKES TO BE FAIRLY
SMALL. BUT AS THE COLDER AIR ARRIVES...IT DOES ATTEMPT TO PUSH THE
CLOUD LAYER INTO THE DGZ AND HELP SNOW RATIOS. BUT WITH THE LIMITED
CLOUD DEPTH/MOISTURE TO WORK WITH...WOULDN/T EXPECT MUCH MORE THAN
AN INCH OR TWO OF TOTAL ACCUMULATION BY THE TIME IT STARTS WINDING
DOWN ON FRIDAY. THE HIGHEST AMOUNTS WILL BE IN THE FAVORED UPSLOPE
LOCATIONS WITH NORTHEAST WINDS...ESPECIALLY IN/NEAR THE HURON
MOUNTAINS WHICH COULD APPROACH 3 INCHES.
A BUILDING CANADIAN HIGH OVER HUDSON BAY WILL SLIDE A RIDGE SOUTH
INTO THE UPPER GREAT LAKES REGION FRIDAY AND IT WILL REMAIN INTO THE
FIRST PART OF THE NEXT WEEK. THIS WILL WORK TO REDUCE THE INVERSION
HEIGHTS TO 2KFT AND SHOULD BRING AN END TO THE LAKE ENHANCED/EFFECT
BY FRIDAY NIGHT. WILL GO WITH PARTLY CLOUDY SKIES THROUGH THE
WEEKEND...BUT THERE IS SOME CONCERN THAT THERE COULD BE LINGERING
LOW CLOUDS BELOW THE STRENGTHENING INVERSION DURING THAT TIME.
MAIN QUESTION FOR NEXT WEEK WILL BE THE LOCATION OF A SHORTWAVE
CUTTING THROUGH THE UPPER RIDGE OVER THE WESTERN CONUS AND IT/S
INFLUENCE ON THE UPPER TROUGH ON THE EAST COAST. 00Z ECMWF HOLDS
THE TROUGH OVER THE AREA...WHILE THE GFS TRIES TO PUSH THE RIDGE
OVER THE AREA ON MONDAY. THIS HAS THE POTENTIAL FOR WEAKENING THE
SURFACE RIDGE AND PUSHING SOME PRECIPITATION INTO THE AREA ON THE
EAST SIDE OF A LOW MOVING THROUGH CENTRAL PLAINS OR UPPER
MISSISSIPPI VALLEY. WILL RESPECT THE CONSISTENCY SHOWN IN THE ECMWF
OVER THE LAST SEVERAL DAYS AND TRY TO KEEP MUCH OF THE AREA DRY.
HIGH TEMPERATURES ARE STILL LOOKING TO BE BELOW NORMAL THROUGH THE
LONG TERM PERIOD. LOOKING AT THE LONGER RANGE FORECASTS /EVEN THOUGH
SKILL IS FAIRLY LIMITED/...NOT TOO MANY SIGNS OF SPRING FOR THE
FIRST WEEK OR TWO OF MARCH. GFS/ECMWF ENS MEANS ARE SHOWING 850MB
TEMPS BELOW NORMAL THROUGH THE FIRST WEEK AND GFS ENS 500MB MEAN
HEIGHTS ARE SHOWING A TROUGH REMAINING OVER THE EASTERN CONUS
THROUGH THE MIDDLE OF MARCH. AFTER BEING SPOILED BY WARM
MARCH WEATHER IN 2010/2012...ITS LOOKING LIKE MARCH WILL
BE MORE TRADITIONAL TEMPERATURE WISE. UNFORTUNATELY FOR SOME OF THE
LOCATIONS OF CENTRAL UPPER MICHIGAN THAT HAVE SEEN PROLONGED
DRYNESS...THIS PATTERN WON/T BE SUPPORTIVE OF ANY SIGNIFICANT
PRECIPITATION AND MAINLY JUST LIGHT PRECIPITATION FROM CLIPPERS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1240 PM EST TUE FEB 26 2013
AT KIWD...EXPECT VFR CONDITIONS THRU THE AFTN. HOWEVER...DAYTIME
HEATING HAS LEAD TO OCNL BKN CIGS DEVELOPING OVER WRN UPPER MI PER
SATELLITE IMAGERY. SO THERE MAY BE A FEW PERIODS OF MVFR CIGS THIS
AFTN AT KIWD. KCMX HAS A SIMILAR SETUP TO KIWD...BUT WILL KEY ON
LARGE AREA OF STRATOCU OVER ERN LAKE SUPERIOR WHICH IS MAKING STEADY
PROGRESS WESTWARD. SIMPLE EXTRAPOLATION SUGGESTS MVFR CIGS MAY REACH
KCMX AROUND 22Z. AT KSAW...EXPECT HIGH MVFR CIGS TO RISE SLIGHTLY TO
VFR DURING THE AFTN HRS. TONIGHT INTO WED MORNING...LOW PRES MOVING
TOWARD THE LOWER LAKES WILL CAUSE A CYCLONIC NE FLOW TO STRENGTHEN.
THIS SHOULD RESULT IN MVFR CIGS DEVELOPING WHERE THIS FLOW MOISTENED
BY LAKE SUPERIOR WILL UPSLOPE AT KIWD/KSAW.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 428 PM EST TUE FEB 26 2013
TIGHTENING PRES GRADIENT BTWN HIGH PRES TO THE N AND NW AND LOW PRES
TRACKING THRU THE LWR OHIO VALLEY TO LWR LAKES WILL RESULT IN
NORTHEASTERLY WINDS ACROSS LAKE SUPERIOR INCREASING TO 20-30KT
TONIGHT THRU WED. MIGHT SEE A FEW GALE FORCE GUSTS WED AFTN OVER THE
E HALF. EVEN THOUGH THE LOW CONTINUES TO MOVE E THU...THE HIGH
BUILDING TOWARD THE AREA FROM N WILL MAINTAIN A TIGHT PRES
GRADIENT...RESULTING IN CONTINUED 20-30KT WINDS WITH SOME GALE FORCE
GUSTS POSSIBLE OVER THE E HALF THRU THU MORNING. WINDS WILL THEN
VERY SLOWLY DIMINISH FROM W TO E FRI/SAT AS THE HIGH PRES MOVES
CLOSER...BUT IT WILL PROBABLY BE SAT BEFORE WINDS DROP BLO 20KT
ACROSS THE ENTIRE LAKE. THE PERIOD OF STRONG WINDS WED NIGHT THRU
FRI WILL ALSO BRING THE POTENTIAL FOR FREEZING SPRAY. LIGHT WINDS
UNDER 10KT ARE EXPECTED SUN AS SFC HIGH PRES RIDGE WILL EXTEND FROM
HUDSON BAY S ACROSS LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1240 PM EST TUE FEB 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM EST TUE FEB 26 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW PATTERN
ACRS NAMERICA...WITH THE UPR GRT LKS UNDER A POLAR JET STREAM WELL S
OF ARCTIC BRANCH IN CENTRL CANADA THAT HAS CONFINED THE BITTERLY
COLD ARCTIC AIR TO FAR NRN CANADA. AN ACTIVE SUBTROPICAL BRANCH
DOMINATES THE S HALF OF THE CONUS...WITH A POTENT DISTURBANCE MOVING
INTO THE LOWER-MID MS RIVER VALLEY. A DISTURBANCE WITHIN THE POLAR
BRANCH IS MOVING ACRS UPR MI EARLY THIS MRNG...BUT LIMITED MSTR
DEPTH PER 00Z GRB/APX RAOBS AND GENERAL LARGER SCALE ACYC FLOW
RELATED TO RDG AXIS EXTENDING WWD FM HI CENTER IN SE CANADA HAS
RESTRICTED ANY IMPACT TO AN AREA OF SC. THE BACK EDGE OF THIS CLD
AREA IS JUST INLAND FM THE W SHORE OF UPR MI CLOSER TO INCOMING AREA
OF DRY AIR DEPICTED ON THE 00Z INL/MPX RAOBS AND WHICH IS UNDER
DNVA/LARGE SCALE QVECTOR DVGC BEHIND THE SHRTWV. SKIES OVER FAR NW
WI/WRN LK SUP AND THE MN ARROWHEAD OF MOCLR...WHICH HAS ALLOWED SOME
FOG TO FORM WITH LGT WINDS. HI CLDS ON THE NRN EDGE OF THE
SUBTROPICAL BRANCH DISTURBANCE TO THE S ARE SPREADING SLOWLY NWD
THRU WI.
MAIN FCST CONCERNS TODAY ARE CLD TRENDS/IMPACT ON TEMPS. FOCUS FOR
TNGT SHIFTS TO WHETHER ANY PCPN ASSOCIATED WITH SRN BRANCH
DISTURBANCE WL IMPACT THE SRN CWA.
TODAY...POLAR BRANCH UPR RDG/DNVA/LARGE SCALE QVECTOR DVGC WL
DOMINATE UPR MI TODAY. AS THE SUBTROPICAL BRANCH SFC LO MOVES INTO
THE LOWER OH RIVER VALLEY BY 00Z WED...THE PRES GRADIENT WL TIGHTEN
OVER UPR MI TO THE WSW OF HI CENTERED IN SE CANADA...WITH AN INCRSG
ENE FLOW. ALTHOUGH THE LARGER SCALE NEGATIVE DYNAMICS WOULD INDICATE
A SLOW BREAKUP OF THE SC DOMINATAING MUCH OF THE CWA NOW...THIS LO
CLD IS WIDESPREAD TO THE E OF UPR MI THIS MRNG...THE SOURCE AIRMASS
FOR THE DVLPG E WIND. ON THE OTHER HAND...THE DIFFLUENT NATURE OF
THE LLVL FLOW AS WELL AS STRONG SUBSIDENCE FCST AT H925 SHOULD TEND
TO BREAK UP THE LO CLD. RECENT TRENDS SHOWN ON STLT IMAGERY/SFC OBS
CONFIRM THIS EXPECTATION. DIURNAL HEATING WITH INCRSG LATE FEB SUN
ANGLE WL ALSO TEND TO DISSIPATE THE SC OVER THE LAKES AS H85 TEMPS
ARE FCST TO BE ABOUT -4C...A TYPICAL EARLY SPRING SCENARIO. IN THIS
SCENARIO...SOME DIURNAL CU/SC WOULD TEND TO FORM OVER THE INTERIOR
FOLLOWING INITIAL CLRG. THE COVERAGE OF THIS CLD SHOULD BE LIMITED
BY THE RATHER LO INVRN BASE SHOWN ON NAM/GFS FCST SDNGS. MAINTAINED
OVERALL FLAVOR OF GOING FCST SHOWING A TERND FOR DECREASING CLDS
INTO THIS AFTN...WITH A BIT MORE CLD COVER OVER THE INTERIOR...
ESPECIALLY IN USPLOPE AREAS. MIXING TO H875 ON FCST SDNGS YIELDS HI
TEMPS CLOSE TO 40...MOST LIKELY IN AREAS OVER THE W THAT SEE MORE
SUNSHINE AND DOWNSLOPE IN LLVL ENE FLOW AWAY FM THE COOLING
INFLUENCE OF THE LKS. GOING FCST NEEDS ONLY MINOR ADJUSTMENTS.
TNGT...SUBTROPICAL BRANCH LO IS PROGGED TO MOVE NE INTO OH BY 12Z
WED. THE BULK OF THE NUMERICAL GUIDANCE SHOWS LGT QPF ON THE NW
FLANK OF THIS LO PRES BRUSHING JUST THE SE COUNTIES WITH SOME LGT
PCPN TOWARD 12Z WED...CONSISTENT WITH THE PASSAGE OF THE DEEP LYR
QVECTOR THRU LWR MI. DESPITE CYC NATURE OF THE INCRSG LLVL NE
FLOW...H85 TEMPS NO LOWER THAN ABOUT -5C AS WELL AS FCST DRY H85-7
LYR INDICATE THERE WL BE NO LK EFFECT/ENHANCED PCPN EVEN IF MORE SC
DVLPS IN THE UPSLOPE AREAS. OPTED TO RETAIN GOING SCHC POPS ONLY
CLOSE TO LK MI/BAY OF GREEN BAY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM EST TUE FEB 26 2013
NOT MUCH IN THE WAY OF PRECIPITATION EXPECTED THROUGH THIS LONG TERM
PERIOD...WITH MARCH LIKELY COMING IN LIKE A LAMB /AS NOTED ON THE
PREVIOUS DISCUSSION/.
BY WEDNESDAY THE 500MB LOW WILL BE THE CLOSEST IT WILL GET TO THE
CWA...TRACKING FROM OHIO TO NE PENNSYLVANIA...SQUEEZING THE RIDGE
NORTH INTO ONTARIO. EXPECT NE FLOW AT THE SFC AND ALOFT WEDNESDAY.
THE 25/12Z CONTINUES TO SHOW A SOUTHERLY TREND TO THE TRACK...WITH A
DOUBLE BARREL LOW SPLITTING THE APPALACHIANS MERGING ACROSS THE NEW
ENGLAND STATES WEDNESDAY NIGHT. A MEER 24 HOURS AGO THE NAM SOLUTION
WAS FOR THE SURFACE LOW TO SWING ACROSS CENTRAL LOWER MICHIGAN...NOW
IT LOOKS TO BE MORE IN LINE IF NOT SLIGHTLY SLOWER THAN THE
ECMWF/GFS ON WEDNESDAY.
STRONG HIGH PRESSURE STRETCHING ACROSS NORTH CENTRAL CANADA ON
TUESDAY WILL PUSH INTO HUDSON BAY AND MANITOBA/ONTARIO
WEDNESDAY/WEDNESDAY NIGHT...WITH THE RIDGE EDGING ACROSS LAKE
SUPERIOR THURSDAY NIGHT THROUGH AT LEAST SUNDAY MORNING. WE STILL
EXPECT SOME BREEZY CONDITIONS NEAR THE LAKE SUPERIOR SHORELINE
WEDNESDAY THROUGH THURSDAY /PUSHING ACROSS MUCH OF CENTRAL UPPER
MICHIGAN DURING THE DAY THURSDAY/. WINDS WILL SLOWLY DIMINISH AS THE
LOW CONTINUES TO EXIT EAST AND THE SURFACE HIGH PUSHES OVERHEAD.
AS FOR THE CHANCE OF PRECIPITATION THROUGH THE PERIOD...IT IS PRETTY
MINIMAL. THE SYNOPTIC SNOW WILL ONLY CLIP AREAS NEAR LAKE MICHIGAN
WEDNESDAY INTO WEDNESDAY EVENING. EVEN WITH THE FAVORABLE UPSLOPE
WINDS OFF LAKE SUPERIOR...TEMPERATURES AT AND ABOVE THE SURFACE WILL
BE MARGINAL TO SUPPORT ANY ACCUMULATING SNOW SHOWERS.
COLDER AIR WILL FINALLY COME IN FOR THE END OF THE WORK WEEK...WITH
850MB TEMPERATURES FALLING TO AROUND -11C FRIDAY AFTERNOON...AND -12
TO -14C FRIDAY NIGHT THROUGH AT LEAST SUNDAY /WITH N-NE WINDS
CONTINUING THROUGH SATURDAY/.
THE 25/12Z ECMWF KEEPS THE RIDGE IN PLACE THROUGH TUESDAY...BECOMING
OUT OF PHASE WITH THE 25/18Z GFS BY MONDAY NIGHT /STRONG 1044MB HIGH
OVER NORTHERN MANITOBA AND ONTARIO...COMPARED TO THE 1005MB LOW
ACROSS ONTARIO/. WHILE THE 26/00Z GFS DID COME IT SLIGHTLY BETTER
AGREEMENT...IT JUST CAN NOT BEAT THE RUN TO RUN CONSISTENCY BEING
SHOWN BY THE ECMWF. CUT BACK THE SLIGHT CHANCE POPS GIVEN WITH A
CONSENSUS OF THE MODELS FOR DAY 6/MONDAY TO RIGHT ALONG THE
WISCONSIN BORDER...MINIMIZING THE INFLUENCE OF THE 26/00Z GFS RUN ON
THE POPS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1240 PM EST TUE FEB 26 2013
AT KIWD...EXPECT VFR CONDITIONS THRU THE AFTN. HOWEVER...DAYTIME
HEATING HAS LEAD TO OCNL BKN CIGS DEVELOPING OVER WRN UPPER MI PER
SATELLITE IMAGERY. SO THERE MAY BE A FEW PERIODS OF MVFR CIGS THIS
AFTN AT KIWD. KCMX HAS A SIMILAR SETUP TO KIWD...BUT WILL KEY ON
LARGE AREA OF STRATOCU OVER ERN LAKE SUPERIOR WHICH IS MAKING STEADY
PROGRESS WESTWARD. SIMPLE EXTRAPOLATION SUGGESTS MVFR CIGS MAY REACH
KCMX AROUND 22Z. AT KSAW...EXPECT HIGH MVFR CIGS TO RISE SLIGHTLY TO
VFR DURING THE AFTN HRS. TONIGHT INTO WED MORNING...LOW PRES MOVING
TOWARD THE LOWER LAKES WILL CAUSE A CYCLONIC NE FLOW TO STRENGTHEN.
THIS SHOULD RESULT IN MVFR CIGS DEVELOPING WHERE THIS FLOW MOISTENED
BY LAKE SUPERIOR WILL UPSLOPE AT KIWD/KSAW.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 357 AM EST TUE FEB 26 2013
A RIDGE OF HIGH PRESSURE ACROSS LAKE SUPERIOR WILL PUSH NORTHWARD
TODAY...IN ADVANCE OF WEAKENING LOW PRESSURE SLIDING FROM SOUTHERN
MISSOURI THIS MORNING TO FAR SOUTHEASTERN LOWER MICHIGAN AND OHIO
WEDNESDAY MORNING...AND EXITING ACROSS NEW YORK WEDNESDAY NIGHT. AS
A RESULT...EXPECT A TROUGH OVER LAKE SUPERIOR WITH STEADY N-NE WINDS
FROM MID AFTERNOON THROUGH THE REST OF THE WORK WEEK. THE STRONGEST
WINDS...WITH A FEW GUSTS NEARING 35KTS CAN BE EXPECTED WEDNESDAY
INTO THURSDAY AS LAKE SUPERIOR BECOMES PINNED BETWEEN THE LOW
PRESSURE SYSTEM TO OUR SOUTHEAST AND STRONG HIGH PRESSURE EDGING IN
FROM THE NORTHWEST. GIVEN THE STRONGER WINDS AND COOLER AIR SLIDING
IN...FREEZING SPRAY WILL BE POSSIBLE. HIGH PRESSURE WILL WIN OUT
FRIDAY...WITH A RIDGE RESIDING ACROSS LAKE SUPERIOR THROUGH AT LEAST
SATURDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...ROLFSON
MARINE...KF
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1122 AM EST TUE FEB 26 2013
.SYNOPSIS...
ISSUED AT 324 AM EST TUE FEB 26 2013
A STORM SYSTEM GATHERING STRENGTH ACROSS ARKANSAS EARLY THIS MORNING
WILL APPROACH LOWER MICHIGAN THIS AFTERNOON AND EVENING.
PRECIPITATION WILL DEVELOP ACROSS THE AREA FROM SOUTH TO NORTH
DURING THE AFTERNOON AND EVENING HOURS. A MIXTURE OF RAIN...SNOW...
AND SOME SLEET WILL BE POSSIBLE AS PRECIPITATION DEVELOPS. ALL
PRECIPITATION WILL QUICKLY CHANGE OVER TO SNOW. SNOW ACCUMULATIONS
WILL RANGE FROM 2 INCHES OR SO UP NORTH...TO 6 INCHES DOWN SOUTH BY
WEDNESDAY MORNING. LIGHT SNOW WILL CONTINUE WEDNESDAY AND WEDNESDAY
NIGHT WITH ONLY LIGHT ADDITIONAL ACCUMULATIONS EXPECTED.
&&
.UPDATE...
ISSUED AT 1117 AM EST TUE FEB 26 2013
WITH THE WARM LAYER FURTHER NORTH...MORE OF A MIX MENTIONED IN THE
FORECAST FOR THIS AFTERNOON. THIS MIX WILL CUT INTO THE OVERALL
SNOW AMOUNTS...ESPECIALLY ALONG I 94. WHILE AIR TEMPERATURES HAVE
RISEN ABOVE FREEZING...AS THE PRECIPITATION MOVES IN WE WILL WET
BULB DOWN TO THE LOW 30S. AS A RESULT FREEZING RAIN COULD OCCUR. UPDATES
TO THE PRODUCTS HAVE BEEN ISSUED.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 324 AM EST TUE FEB 26 2013
MAIN FOCUS OF THE FCST IS OBVIOUSLY THE INCOMING SYSTEM AND
EVALUATING WHETHER ANY ADJUSTMENTS ARE NEEDED TO THE GOING
HEADLINES. AT THIS TIME...WE WILL BE HOLDING ON TO THE ADVISORY AS
IT IS AS THERE IS NOT A GOOD REASON TO CHANGE THINGS FOR NOW.
THE LATEST MODEL RUNS FROM THE 00Z CYCLE ARE PRETTY MUCH MAINTAINING
GOOD CONTINUITY FROM THEIR PREVIOUS RUNS. WE ARE STILL EXPECTING A
NICE AND POSSIBLY HEAVY BURST OF PCPN INITIALLY BY MID AFTERNOON
DOWN SOUTH ALONG I-94...AND SPREADING NORTH INTO THE MID EVENING
HOURS TONIGHT. THIS BURST IS THE RESULT OF STRONG ISENTROPIC
ASCENT/MOISTURE TRANSPORT ALOFT OUT AHEAD OF THE SYSTEM AND
RESULTING STRONG FGEN DEVELOPING AS A RESULT. WE CONTINUE
TO SEE A GOOD CROSS-HAIRS SIGNATURE WHERE THE BEST LIFT OCCURS IN THE
DGZ. IN ADDITION...A WEAKNESS IN THE STABILITY DOES EXISTS WHICH
WILL ONLY ENHANCE THE BAND OF PCPN. IT SHOULD BE MENTIONED THAT A
GOOD PORTION OF THE STORM TOTALS ARE EXPECTED TO COME FROM THIS
HEAVY BURST THIS AFTERNOON/EVENING. LOW SNOW TO WATER RATIOS WILL
LIMIT SNOW ACCUMULATIONS SOME. THE HEAVIER BAND OF PCPN SHOULD
PRODUCE BRIEFLY HIGHER SNOW TO WATER RATIOS WITH THE DGZ AND LIFT
COINCIDING.
THE MAIN CONCERN IN THE WHOLE EVENT THAT WE ARE MONITORING IS THE
POTENTIAL FOR A LITTLE MORE POSSIBLE RAIN AT THE ONSET DOWN SOUTH. A
COUPLE OF THE MODELS...SPECIFICALLY THE NAM AND GEM ARE INDICATING A
BIT BETTER CHC OF RAIN DOWN SOUTH THIS AFTERNOON AND EARLY EVENING
BEFORE ALL PCPN CHANGES OVER TO SNOW DUE TO EVAPORATIVE COOLING. THE
GFS AND EURO EACH BRING SUFFICIENTLY DEEP WET BULB ZERO HEIGHTS
ALMOST TO I-94 BEFORE EVAPORATIVE COOLING WIPES THAT OUT BY MID
EVENING. WE ARE LEANING HEAVILY TOWARD THE GFS AND EURO AT THIS TIME
AS THEY HAVE BEEN VERY CONSISTENT. WE HAVE ADDED IN/MAINTAINED A CHC
OF RAIN ACROSS THE FAR SOUTH IN THE EVENT THAT THE WET BULB ZERO
HEIGHTS ARE JUST DEEP ENOUGH TO ALLOW FOR SOME RAIN. SLEET REMAINS
POSSIBLE STILL ALSO AT THE ONSET DOWN SOUTH WITH A WARM NOSE ALOFT
AND THEN A COLD LAYER BEFORE A SLIGHTLY ABOVE FREEZING SFC TEMP.
WE WILL SEE THE ISENTROPIC ASCENT BURST OF PCPN SHIFT NORTH AND EAST
THIS EVENING BEFORE WEAKENING AND MOVING OUT AS THE MAIN PUSH OF
WARMTH AND MOISTURE SHIFTS SE WITH THE TRANSFER OF ENERGY EXPECTED
TO TAKE PLACE THIS EVENING. WE STILL EXPECT TO SEE A LULL IN THE
SNOW BEFORE IT WILL PICK UP ONCE AGAIN SOME LATER IN THE EVENING AND
OVERNIGHT AS THE DEFORMATION ZONE/TROWAL MOVES INTO THE AREA. THE
SECOND ROUND IS EXPECTED TO BRING LIGHTER ACCUMULATIONS THAN THE
INITIAL BURST FOR MANY LOCATIONS. THERE WILL BE NO P-TYPE ISSUES
WITH THIS ROUND AS EVAPORATIVE COOLING WILL MAKE THE ENTIRE COLUMN
COLD ENOUGH FOR SNOW.
WE WILL SEE THE SNOW TAPER OFF SOME THEN FOR WED AND WED NIGHT.
HOWEVER WE WILL CONTINUE TO SEE INTERVALS OF LIGHT SNOW AS THE UPPER
LOW GETS HUNG UP TO OUR EAST AND WE WILL REMAIN CYCLONIC ALOFT. THIS
IS SOMEWHAT SIMILAR TO THE EVENT LATE LAST WEEK DUE TO THE UPPER
LOW. IT IS DIFFERENT IN THE SENSE THAT THERE WILL NOT REALLY BE A
LAKE CONTRIBUTION DUE TO H850 TEMPS NOT BEING COLD ENOUGH AND THAT
THE FLOW WILL REMAIN OFFSHORE THROUGH WED NIGHT. ACCUMULATIONS
SHOULD BE LIMITED TO AROUND AN INCH OR SO FOR EACH WED AND THEN
AGAIN WED NIGHT. THE UPPER LOW WILL PULL AWAY ON THU AND GRADUALLY
TAKE THE SNOW CHANCES EAST OF THE AREA THROUGH THE DAY.
.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 324 AM EST TUE FEB 26 2013
FOR NOW I WILL CONTINUE OUR IDEA OF A PERIOD OF PRECIPITATION FREE
WEATHER FOR SOUTHWEST MICHIGAN FROM FRIDAY INTO MONDAY. TEMPERATURES
WILL BE COLDER THAN NORMAL DURING THIS TIME PERIOD.
MY CONFIDENCE IN THIS FORECAST IS A LITTLE LESS THAN YESTERDAY SINCE
EVEN THOUGH THE MODELS HAVE BEEN SOMEWHAT CONSISTENT WITH THE
LONG WAVE PATTERN FORECAST...THERE ARE NUMEROUS DETAIL ISSUES AS TO
HOW INDIVIDUAL SHORTWAVES ARE HANDLED AS THEY MOVE THROUGH THE MEAN
WESTERN RIDGE INTO THE CENTRAL GREAT LAKES.
TWO LARGE SCALE FEATURES WORK TOGETHER TO CREATE AN AMPLIFIED UPPER
AIR PATTERN OVER THE CONUS DURING THIS TIME PERIOD. THERE IS A
POWERFUL PACIFIC STORM APPROACHING THE DATELINE (AS I WRITE THIS)
THAT BOOTS THE SYSTEM ALREADY THERE DOWNSTREAM OVER THE WESTERN
RIDGE INTO WEST CENTRAL CONUS IN THE FRI/SAT TIME FRAME. SINCE THE
STORM HEADING TOWARD THE DATELINE IS POWERFUL STORM...IT ENDS UP
BUILDING THE WESTERN RIDGE EVEN STRONGER THAN IT CURRENTLY IS. THAT
HELPS TO CREATE MORE NORTHERLY FLOW AT MID AND UPPER LEVELS OVER
CENTRAL NORTH AMERICA. MEANWHILE THERE IS A LARGE BLOCKING UPPER
HIGH EAST OF GREENLAND THAT IS CURRENTLY RETROGRADING. THAT IS
FORCING ANY SYSTEMS SOUTH OF IT. THE COMBINATION OF THOSE TWO
SYSTEMS...ONE OVER THE NORTH ATLANTIC AND THE OTHER OVER THE NORTH
PACIFIC...WILL PROVIDE A STEADY SUPPLY OF COLD (BUT NOT ARCTIC) AIR
INTO EARLY NEXT WEEK DUE TO THE LARGELY NORTH NORTHWEST FLOW AT
UPPER LEVELS DURING THAT TIME.
ANOTHER ASPECT TO THIS IS THE EXTENSION OF THE HUDSON BAY HIGH INTO
LOWER MICHIGAN INTO THIS COMING WEEKEND. THAT CREATES A NORTH
NORTHEAST SURFACE WIND FLOW. THAT IN TURN WILL KEEP ANY LAKE EFFECT
ON THE WISCONSIN SIDE OF LAKE MICHIGAN INTO EARLY NEXT WEEK.
THE ONLY REAL ISSUE IS THAT THERE ARE SEVERAL MINOR SHORTWAVES
MOVING THROUGH THE UPPER LEVEL FLOW DURING THIS TIME PERIOD. IT IS
POSSIBLE IF ONE OF THOSE SHORTWAVES GOT A TOUCH MORE AMPLIFIED WE
COULD BE SEEING AND EXTEND PERIOD OF LIGHT SNOW. NOW THOUGH IT LOOKS
LIKE ANY SYSTEMS WILL STAY WEST AND SOUTH OF LOWER MICHIGAN...
BRINGING LARGELY DRY BUT COLD WEATHER.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 647 AM EST TUE FEB 26 2013
LITTLE QUESTION THE CURRENT VFR CIGS/VSBY WILL GO TO SOLID IFR
CIGS/VSBY BY 00Z WITH SNOW ACROSS ALL TAF SITES.
THE TIMING WAS FOR WHEN THE PRECIPITATION REACHES EACH TAF SITE
AND THE TIMING OF THE CHANGE FROM RAIN TO SNOW WAS BASED ON
COMBINATION OF THE HRRR AND 06Z NAM12 RADAR FORECASTS WITH SOME
CONSIDERATION TO HOW WELL THOSE FORECAST FIELDS MATCH THE CURRENT
PRECIPITATION PATTERN. BOTH ARE SIMILAR ON TIMING AND DO A GOOD
JOB OF MATCHING WERE THE PRECIPITATION HAS BEEN THE PAST FEW
HOURS. THE HRRR IS MUCH MORE RELUCTANT TO CHANGE THE RAIN TO
SNOW... IN FACT THE HRRR HAS NO SNOW OVER ANY PART OF THE CWA
THROUGH 00Z... IT SHOWS ALL RAIN. CURRENTLY (11Z) THE RAIN TO SNOW
LINE IS IN CENTRAL ILLINOIS... THE HRRR HAS IT EASTERN IOWA. THE
RAIN/SNOW LINE IS BETTER MATCHED ON THE NAM12 WHICH HAS IT WHERE
IT CURRENTLY IS. SO... I USED THAT FOR MY RAIN TO SNOW DECISION MAKING IN
THE TAFS. ONCE THE PRECIPITATION BEGINS... IT WILL QUICKLY LOWER
THE CEILING TO IFR AND WITH THE SLOW MOVEMENT OF THE SYSTEM THE
IFR CIGS/VSBY WILL CONTINUE THROUGH THE NIGHT INTO WEDNESDAY.
&&
.MARINE...
ISSUED AT 1117 AM EST TUE FEB 26 2013
NO MAJOR CHANGES. WINDS HAVE RISEN TO SCA CRITERIA. WILL BE CLOSE
TO GALES AT TIMES.
&&
.HYDROLOGY...
ISSUED AT 324 AM EST TUE FEB 26 2013
THE ONLY THING OF CONCERN IN HYDROLOGY REMAINS THE POTENTIAL FOR ICE
JAMS. THERE HAS BEEN NOTHING TO NOTE IN THE LAST COUPLE OF DAYS. WE
WILL CONTINUE TO MONITOR FOR ANY POTENTIAL PROBLEMS THAT MAY CROP UP
AS MILD TEMPS WORK ON ANY ICE ON THE RIVERS AND STREAMS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR MIZ064>067-
071>074.
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST
WEDNESDAY FOR MIZ044>046-050>052-056>059.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR LMZ844>849.
&&
$$
UPDATE...MJS
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...WDM
AVIATION...WDM
HYDROLOGY...NJJ
MARINE...MJS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
648 AM EST TUE FEB 26 2013
.SYNOPSIS...
ISSUED AT 324 AM EST TUE FEB 26 2013
A STORM SYSTEM GATHERING STRENGTH ACROSS ARKANSAS EARLY THIS MORNING
WILL APPROACH LOWER MICHIGAN THIS AFTERNOON AND EVENING.
PRECIPITATION WILL DEVELOP ACROSS THE AREA FROM SOUTH TO NORTH
DURING THE AFTERNOON AND EVENING HOURS. A MIXTURE OF RAIN...SNOW...
AND SOME SLEET WILL BE POSSIBLE AS PRECIPITATION DEVELOPS. ALL
PRECIPITATION WILL QUICKLY CHANGE OVER TO SNOW. SNOW ACCUMULATIONS
WILL RANGE FROM 2 INCHES OR SO UP NORTH...TO 6 INCHES DOWN SOUTH BY
WEDNESDAY MORNING. LIGHT SNOW WILL CONTINUE WEDNESDAY AND WEDNESDAY
NIGHT WITH ONLY LIGHT ADDITIONAL ACCUMULATIONS EXPECTED.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 324 AM EST TUE FEB 26 2013
MAIN FOCUS OF THE FCST IS OBVIOUSLY THE INCOMING SYSTEM AND
EVALUATING WHETHER ANY ADJUSTMENTS ARE NEEDED TO THE GOING
HEADLINES. AT THIS TIME...WE WILL BE HOLDING ON TO THE ADVISORY AS
IT IS AS THERE IS NOT A GOOD REASON TO CHANGE THINGS FOR NOW.
THE LATEST MODEL RUNS FROM THE 00Z CYCLE ARE PRETTY MUCH MAINTAINING
GOOD CONTINUITY FROM THEIR PREVIOUS RUNS. WE ARE STILL EXPECTING A
NICE AND POSSIBLY HEAVY BURST OF PCPN INITIALLY BY MID AFTERNOON
DOWN SOUTH ALONG I-94...AND SPREADING NORTH INTO THE MID EVENING
HOURS TONIGHT. THIS BURST IS THE RESULT OF STRONG ISENTROPIC
ASCENT/MOISTURE TRANSPORT ALOFT OUT AHEAD OF THE SYSTEM AND
RESULTING STRONG FGEN DEVELOPING AS A RESULT. WE CONTINUE
TO SEE A GOOD CROSS-HAIRS SIGNATURE WHERE THE BEST LIFT OCCURS IN THE
DGZ. IN ADDITION...A WEAKNESS IN THE STABILITY DOES EXISTS WHICH
WILL ONLY ENHANCE THE BAND OF PCPN. IT SHOULD BE MENTIONED THAT A
GOOD PORTION OF THE STORM TOTALS ARE EXPECTED TO COME FROM THIS
HEAVY BURST THIS AFTERNOON/EVENING. LOW SNOW TO WATER RATIOS WILL
LIMIT SNOW ACCUMULATIONS SOME. THE HEAVIER BAND OF PCPN SHOULD
PRODUCE BRIEFLY HIGHER SNOW TO WATER RATIOS WITH THE DGZ AND LIFT
COINCIDING.
THE MAIN CONCERN IN THE WHOLE EVENT THAT WE ARE MONITORING IS THE
POTENTIAL FOR A LITTLE MORE POSSIBLE RAIN AT THE ONSET DOWN SOUTH. A
COUPLE OF THE MODELS...SPECIFICALLY THE NAM AND GEM ARE INDICATING A
BIT BETTER CHC OF RAIN DOWN SOUTH THIS AFTERNOON AND EARLY EVENING
BEFORE ALL PCPN CHANGES OVER TO SNOW DUE TO EVAPORATIVE COOLING. THE
GFS AND EURO EACH BRING SUFFICIENTLY DEEP WET BULB ZERO HEIGHTS
ALMOST TO I-94 BEFORE EVAPORATIVE COOLING WIPES THAT OUT BY MID
EVENING. WE ARE LEANING HEAVILY TOWARD THE GFS AND EURO AT THIS TIME
AS THEY HAVE BEEN VERY CONSISTENT. WE HAVE ADDED IN/MAINTAINED A CHC
OF RAIN ACROSS THE FAR SOUTH IN THE EVENT THAT THE WET BULB ZERO
HEIGHTS ARE JUST DEEP ENOUGH TO ALLOW FOR SOME RAIN. SLEET REMAINS
POSSIBLE STILL ALSO AT THE ONSET DOWN SOUTH WITH A WARM NOSE ALOFT
AND THEN A COLD LAYER BEFORE A SLIGHTLY ABOVE FREEZING SFC TEMP.
WE WILL SEE THE ISENTROPIC ASCENT BURST OF PCPN SHIFT NORTH AND EAST
THIS EVENING BEFORE WEAKENING AND MOVING OUT AS THE MAIN PUSH OF
WARMTH AND MOISTURE SHIFTS SE WITH THE TRANSFER OF ENERGY EXPECTED
TO TAKE PLACE THIS EVENING. WE STILL EXPECT TO SEE A LULL IN THE
SNOW BEFORE IT WILL PICK UP ONCE AGAIN SOME LATER IN THE EVENING AND
OVERNIGHT AS THE DEFORMATION ZONE/TROWAL MOVES INTO THE AREA. THE
SECOND ROUND IS EXPECTED TO BRING LIGHTER ACCUMULATIONS THAN THE
INITIAL BURST FOR MANY LOCATIONS. THERE WILL BE NO P-TYPE ISSUES
WITH THIS ROUND AS EVAPORATIVE COOLING WILL MAKE THE ENTIRE COLUMN
COLD ENOUGH FOR SNOW.
WE WILL SEE THE SNOW TAPER OFF SOME THEN FOR WED AND WED NIGHT.
HOWEVER WE WILL CONTINUE TO SEE INTERVALS OF LIGHT SNOW AS THE UPPER
LOW GETS HUNG UP TO OUR EAST AND WE WILL REMAIN CYCLONIC ALOFT. THIS
IS SOMEWHAT SIMILAR TO THE EVENT LATE LAST WEEK DUE TO THE UPPER
LOW. IT IS DIFFERENT IN THE SENSE THAT THERE WILL NOT REALLY BE A
LAKE CONTRIBUTION DUE TO H850 TEMPS NOT BEING COLD ENOUGH AND THAT
THE FLOW WILL REMAIN OFFSHORE THROUGH WED NIGHT. ACCUMULATIONS
SHOULD BE LIMITED TO AROUND AN INCH OR SO FOR EACH WED AND THEN
AGAIN WED NIGHT. THE UPPER LOW WILL PULL AWAY ON THU AND GRADUALLY
TAKE THE SNOW CHANCES EAST OF THE AREA THROUGH THE DAY.
.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 324 AM EST TUE FEB 26 2013
FOR NOW I WILL CONTINUE OUR IDEA OF A PERIOD OF PRECIPITATION FREE
WEATHER FOR SOUTHWEST MICHIGAN FROM FRIDAY INTO MONDAY. TEMPERATURES
WILL BE COLDER THAN NORMAL DURING THIS TIME PERIOD.
MY CONFIDENCE IN THIS FORECAST IS A LITTLE LESS THAN YESTERDAY SINCE
EVEN THOUGH THE MODELS HAVE BEEN SOMEWHAT CONSISTENT WITH THE
LONG WAVE PATTERN FORECAST...THERE ARE NUMEROUS DETAIL ISSUES AS TO
HOW INDIVIDUAL SHORTWAVES ARE HANDLED AS THEY MOVE THROUGH THE MEAN
WESTERN RIDGE INTO THE CENTRAL GREAT LAKES.
TWO LARGE SCALE FEATURES WORK TOGETHER TO CREATE AN AMPLIFIED UPPER
AIR PATTERN OVER THE CONUS DURING THIS TIME PERIOD. THERE IS A
POWERFUL PACIFIC STORM APPROACHING THE DATELINE (AS I WRITE THIS)
THAT BOOTS THE SYSTEM ALREADY THERE DOWNSTREAM OVER THE WESTERN
RIDGE INTO WEST CENTRAL CONUS IN THE FRI/SAT TIME FRAME. SINCE THE
STORM HEADING TOWARD THE DATELINE IS POWERFUL STORM...IT ENDS UP
BUILDING THE WESTERN RIDGE EVEN STRONGER THAN IT CURRENTLY IS. THAT
HELPS TO CREATE MORE NORTHERLY FLOW AT MID AND UPPER LEVELS OVER
CENTRAL NORTH AMERICA. MEANWHILE THERE IS A LARGE BLOCKING UPPER
HIGH EAST OF GREENLAND THAT IS CURRENTLY RETROGRADING. THAT IS
FORCING ANY SYSTEMS SOUTH OF IT. THE COMBINATION OF THOSE TWO
SYSTEMS...ONE OVER THE NORTH ATLANTIC AND THE OTHER OVER THE NORTH
PACIFIC...WILL PROVIDE A STEADY SUPPLY OF COLD (BUT NOT ARCTIC) AIR
INTO EARLY NEXT WEEK DUE TO THE LARGELY NORTH NORTHWEST FLOW AT
UPPER LEVELS DURING THAT TIME.
ANOTHER ASPECT TO THIS IS THE EXTENSION OF THE HUDSON BAY HIGH INTO
LOWER MICHIGAN INTO THIS COMING WEEKEND. THAT CREATES A NORTH
NORTHEAST SURFACE WIND FLOW. THAT IN TURN WILL KEEP ANY LAKE EFFECT
ON THE WISCONSIN SIDE OF LAKE MICHIGAN INTO EARLY NEXT WEEK.
THE ONLY REAL ISSUE IS THAT THERE ARE SEVERAL MINOR SHORTWAVES
MOVING THROUGH THE UPPER LEVEL FLOW DURING THIS TIME PERIOD. IT IS
POSSIBLE IF ONE OF THOSE SHORTWAVES GOT A TOUCH MORE AMPLIFIED WE
COULD BE SEEING AND EXTEND PERIOD OF LIGHT SNOW. NOW THOUGH IT LOOKS
LIKE ANY SYSTEMS WILL STAY WEST AND SOUTH OF LOWER MICHIGAN...
BRINGING LARGELY DRY BUT COLD WEATHER.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 647 AM EST TUE FEB 26 2013
LITTLE QUESTION THE CURRENT VFR CIGS/VSBY WILL GO TO SOLID IFR
CIGS/VSBY BY 00Z WITH SNOW ACROSS ALL TAF SITES.
THE TIMING WAS FOR WHEN THE PRECIPITATION REACHES EACH TAF SITE
AND THE TIMING OF THE CHANGE FROM RAIN TO SNOW WAS BASED ON
COMBINATION OF THE HRRR AND 06Z NAM12 RADAR FORECASTS WITH SOME
CONSIDERATION TO HOW WELL THOSE FORECAST FIELDS MATCH THE CURRENT
PRECIPITATION PATTERN. BOTH ARE SIMILAR ON TIMING AND DO A GOOD
JOB OF MATCHING WERE THE PRECIPITATION HAS BEEN THE PAST FEW
HOURS. THE HRRR IS MUCH MORE RELUCTANT TO CHANGE THE RAIN TO
SNOW... IN FACT THE HRRR HAS NO SNOW OVER ANY PART OF THE CWA
THROUGH 00Z... IT SHOWS ALL RAIN. CURRENTLY (11Z) THE RAIN TO SNOW
LINE IS IN CENTRAL ILLINOIS... THE HRRR HAS IT EASTERN IOWA. THE
RAIN/SNOW LINE IS BETTER MATCHED ON THE NAM12 WHICH HAS IT WHERE
IT CURRENTLY IS. SO... I USED THAT FOR MY RAIN TO SNOW DECISION MAKING IN
THE TAFS. ONCE THE PRECIPITATION BEGINS... IT WILL QUICKLY LOWER
THE CEILING TO IFR AND WITH THE SLOW MOVEMENT OF THE SYSTEM THE
IFR CIGS/VSBY WILL CONTINUE THROUGH THE NIGHT INTO WEDNESDAY.
&&
.MARINE...
ISSUED AT 324 AM EST TUE FEB 26 2013
WE HAVE EXTENDED THE SMALL CRAFT ADVISORY OUT ANOTHER 24 HOURS
THROUGH 12Z THU. WINDS ARE EXPECTED TO REMAIN ABOVE 25 KNOTS AT
LEAST THROUGH THU MORNING...AND VERY LIKELY BEYOND THEN. WE STILL
CAN NOT RULE OUT SOME GALE GUSTS LATER TODAY AND TONIGHT...HOWEVER
IT SHOULD BE THE EXCEPTION RATHER THAN THE RULE DUE TO THE OFFSHORE
FLOW AND A LACK OF COLD AIR ADVECTION.
&&
.HYDROLOGY...
ISSUED AT 324 AM EST TUE FEB 26 2013
THE ONLY THING OF CONCERN IN HYDROLOGY REMAINS THE POTENTIAL FOR ICE
JAMS. THERE HAS BEEN NOTHING TO NOTE IN THE LAST COUPLE OF DAYS. WE
WILL CONTINUE TO MONITOR FOR ANY POTENTIAL PROBLEMS THAT MAY CROP UP
AS MILD TEMPS WORK ON ANY ICE ON THE RIVERS AND STREAMS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 6 AM EST
WEDNESDAY FOR MIZ064>067-071>074.
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST
WEDNESDAY FOR MIZ044>046-050>052-056>059.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR LMZ844>849.
&&
$$
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...WDM
AVIATION...WDM
HYDROLOGY...NJJ
MARINE...NJJ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
621 AM EST TUE FEB 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM EST TUE FEB 26 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW PATTERN
ACRS NAMERICA...WITH THE UPR GRT LKS UNDER A POLAR JET STREAM WELL S
OF ARCTIC BRANCH IN CENTRL CANADA THAT HAS CONFINED THE BITTERLY
COLD ARCTIC AIR TO FAR NRN CANADA. AN ACTIVE SUBTROPICAL BRANCH
DOMINATES THE S HALF OF THE CONUS...WITH A POTENT DISTURBANCE MOVING
INTO THE LOWER-MID MS RIVER VALLEY. A DISTURBANCE WITHIN THE POLAR
BRANCH IS MOVING ACRS UPR MI EARLY THIS MRNG...BUT LIMITED MSTR
DEPTH PER 00Z GRB/APX RAOBS AND GENERAL LARGER SCALE ACYC FLOW
RELATED TO RDG AXIS EXTENDING WWD FM HI CENTER IN SE CANADA HAS
RESTRICTED ANY IMPACT TO AN AREA OF SC. THE BACK EDGE OF THIS CLD
AREA IS JUST INLAND FM THE W SHORE OF UPR MI CLOSER TO INCOMING AREA
OF DRY AIR DEPICTED ON THE 00Z INL/MPX RAOBS AND WHICH IS UNDER
DNVA/LARGE SCALE QVECTOR DVGC BEHIND THE SHRTWV. SKIES OVER FAR NW
WI/WRN LK SUP AND THE MN ARROWHEAD OF MOCLR...WHICH HAS ALLOWED SOME
FOG TO FORM WITH LGT WINDS. HI CLDS ON THE NRN EDGE OF THE
SUBTROPICAL BRANCH DISTURBANCE TO THE S ARE SPREADING SLOWLY NWD
THRU WI.
MAIN FCST CONCERNS TODAY ARE CLD TRENDS/IMPACT ON TEMPS. FOCUS FOR
TNGT SHIFTS TO WHETHER ANY PCPN ASSOCIATED WITH SRN BRANCH
DISTURBANCE WL IMPACT THE SRN CWA.
TODAY...POLAR BRANCH UPR RDG/DNVA/LARGE SCALE QVECTOR DVGC WL
DOMINATE UPR MI TODAY. AS THE SUBTROPICAL BRANCH SFC LO MOVES INTO
THE LOWER OH RIVER VALLEY BY 00Z WED...THE PRES GRADIENT WL TIGHTEN
OVER UPR MI TO THE WSW OF HI CENTERED IN SE CANADA...WITH AN INCRSG
ENE FLOW. ALTHOUGH THE LARGER SCALE NEGATIVE DYNAMICS WOULD INDICATE
A SLOW BREAKUP OF THE SC DOMINATAING MUCH OF THE CWA NOW...THIS LO
CLD IS WIDESPREAD TO THE E OF UPR MI THIS MRNG...THE SOURCE AIRMASS
FOR THE DVLPG E WIND. ON THE OTHER HAND...THE DIFFLUENT NATURE OF
THE LLVL FLOW AS WELL AS STRONG SUBSIDENCE FCST AT H925 SHOULD TEND
TO BREAK UP THE LO CLD. RECENT TRENDS SHOWN ON STLT IMAGERY/SFC OBS
CONFIRM THIS EXPECTATION. DIURNAL HEATING WITH INCRSG LATE FEB SUN
ANGLE WL ALSO TEND TO DISSIPATE THE SC OVER THE LAKES AS H85 TEMPS
ARE FCST TO BE ABOUT -4C...A TYPICAL EARLY SPRING SCENARIO. IN THIS
SCENARIO...SOME DIURNAL CU/SC WOULD TEND TO FORM OVER THE INTERIOR
FOLLOWING INITIAL CLRG. THE COVERAGE OF THIS CLD SHOULD BE LIMITED
BY THE RATHER LO INVRN BASE SHOWN ON NAM/GFS FCST SDNGS. MAINTAINED
OVERALL FLAVOR OF GOING FCST SHOWING A TERND FOR DECREASING CLDS
INTO THIS AFTN...WITH A BIT MORE CLD COVER OVER THE INTERIOR...
ESPECIALLY IN USPLOPE AREAS. MIXING TO H875 ON FCST SDNGS YIELDS HI
TEMPS CLOSE TO 40...MOST LIKELY IN AREAS OVER THE W THAT SEE MORE
SUNSHINE AND DOWNSLOPE IN LLVL ENE FLOW AWAY FM THE COOLING
INFLUENCE OF THE LKS. GOING FCST NEEDS ONLY MINOR ADJUSTMENTS.
TNGT...SUBTROPICAL BRANCH LO IS PROGGED TO MOVE NE INTO OH BY 12Z
WED. THE BULK OF THE NUMERICAL GUIDANCE SHOWS LGT QPF ON THE NW
FLANK OF THIS LO PRES BRUSHING JUST THE SE COUNTIES WITH SOME LGT
PCPN TOWARD 12Z WED...CONSISTENT WITH THE PASSAGE OF THE DEEP LYR
QVECTOR THRU LWR MI. DESPITE CYC NATURE OF THE INCRSG LLVL NE
FLOW...H85 TEMPS NO LOWER THAN ABOUT -5C AS WELL AS FCST DRY H85-7
LYR INDICATE THERE WL BE NO LK EFFECT/ENHANCED PCPN EVEN IF MORE SC
DVLPS IN THE UPSLOPE AREAS. OPTED TO RETAIN GOING SCHC POPS ONLY
CLOSE TO LK MI/BAY OF GREEN BAY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM EST TUE FEB 26 2013
NOT MUCH IN THE WAY OF PRECIPITATION EXPECTED THROUGH THIS LONG TERM
PERIOD...WITH MARCH LIKELY COMING IN LIKE A LAMB /AS NOTED ON THE
PREVIOUS DISCUSSION/.
BY WEDNESDAY THE 500MB LOW WILL BE THE CLOSEST IT WILL GET TO THE
CWA...TRACKING FROM OHIO TO NE PENNSYLVANIA...SQUEEZING THE RIDGE
NORTH INTO ONTARIO. EXPECT NE FLOW AT THE SFC AND ALOFT WEDNESDAY.
THE 25/12Z CONTINUES TO SHOW A SOUTHERLY TREND TO THE TRACK...WITH A
DOUBLE BARREL LOW SPLITTING THE APPALACHIANS MERGING ACROSS THE NEW
ENGLAND STATES WEDNESDAY NIGHT. A MEER 24 HOURS AGO THE NAM SOLUTION
WAS FOR THE SURFACE LOW TO SWING ACROSS CENTRAL LOWER MICHIGAN...NOW
IT LOOKS TO BE MORE IN LINE IF NOT SLIGHTLY SLOWER THAN THE
ECMWF/GFS ON WEDNESDAY.
STRONG HIGH PRESSURE STRETCHING ACROSS NORTH CENTRAL CANADA ON
TUESDAY WILL PUSH INTO HUDSON BAY AND MANITOBA/ONTARIO
WEDNESDAY/WEDNESDAY NIGHT...WITH THE RIDGE EDGING ACROSS LAKE
SUPERIOR THURSDAY NIGHT THROUGH AT LEAST SUNDAY MORNING. WE STILL
EXPECT SOME BREEZY CONDITIONS NEAR THE LAKE SUPERIOR SHORELINE
WEDNESDAY THROUGH THURSDAY /PUSHING ACROSS MUCH OF CENTRAL UPPER
MICHIGAN DURING THE DAY THURSDAY/. WINDS WILL SLOWLY DIMINISH AS THE
LOW CONTINUES TO EXIT EAST AND THE SURFACE HIGH PUSHES OVERHEAD.
AS FOR THE CHANCE OF PRECIPITATION THROUGH THE PERIOD...IT IS PRETTY
MINIMAL. THE SYNOPTIC SNOW WILL ONLY CLIP AREAS NEAR LAKE MICHIGAN
WEDNESDAY INTO WEDNESDAY EVENING. EVEN WITH THE FAVORABLE UPSLOPE
WINDS OFF LAKE SUPERIOR...TEMPERATURES AT AND ABOVE THE SURFACE WILL
BE MARGINAL TO SUPPORT ANY ACCUMULATING SNOW SHOWERS.
COLDER AIR WILL FINALLY COME IN FOR THE END OF THE WORK WEEK...WITH
850MB TEMPERATURES FALLING TO AROUND -11C FRIDAY AFTERNOON...AND -12
TO -14C FRIDAY NIGHT THROUGH AT LEAST SUNDAY /WITH N-NE WINDS
CONTINUING THROUGH SATURDAY/.
THE 25/12Z ECMWF KEEPS THE RIDGE IN PLACE THROUGH TUESDAY...BECOMING
OUT OF PHASE WITH THE 25/18Z GFS BY MONDAY NIGHT /STRONG 1044MB HIGH
OVER NORTHERN MANITOBA AND ONTARIO...COMPARED TO THE 1005MB LOW
ACROSS ONTARIO/. WHILE THE 26/00Z GFS DID COME IT SLIGHTLY BETTER
AGREEMENT...IT JUST CAN NOT BEAT THE RUN TO RUN CONSISTENCY BEING
SHOWN BY THE ECMWF. CUT BACK THE SLIGHT CHANCE POPS GIVEN WITH A
CONSENSUS OF THE MODELS FOR DAY 6/MONDAY TO RIGHT ALONG THE
WISCONSIN BORDER...MINIMIZING THE INFLUENCE OF THE 26/00Z GFS RUN ON
THE POPS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 620 AM EST TUE FEB 26 2013
ALTHOUGH SOME MRNG GROUND FOG/OCNLY LOWER VSBYS MAY IMPACT CMX/IWD
EARLY THIS MRNG AND BKN CIGS WL LINGER A GOOD PART OF THE DAY AT
SAW...EXPECT VFR CONDITIONS TO PREDOMINATE WITH HI PRES RDG IN
CONTROL. AS LO PRES MOVING TOWARD THE LOWER LKS CAUSES A CYC NE FLOW
TO STRENGTHEN TNGT...SOME MVFR CIGS ARE LIKELY WHERE THIS FLOW
MOISTENED BY LK SUP WL UPSLOPE AT IWD/SAW.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 357 AM EST TUE FEB 26 2013
A RIDGE OF HIGH PRESSURE ACROSS LAKE SUPERIOR WILL PUSH NORTHWARD
TODAY...IN ADVANCE OF WEAKENING LOW PRESSURE SLIDING FROM SOUTHERN
MISSOURI THIS MORNING TO FAR SOUTHEASTERN LOWER MICHIGAN AND OHIO
WEDNESDAY MORNING...AND EXITING ACROSS NEW YORK WEDNESDAY NIGHT. AS
A RESULT...EXPECT A TROUGH OVER LAKE SUPERIOR WITH STEADY N-NE WINDS
FROM MID AFTERNOON THROUGH THE REST OF THE WORK WEEK. THE STRONGEST
WINDS...WITH A FEW GUSTS NEARING 35KTS CAN BE EXPECTED WEDNESDAY
INTO THURSDAY AS LAKE SUPERIOR BECOMES PINNED BETWEEN THE LOW
PRESSURE SYSTEM TO OUR SOUTHEAST AND STRONG HIGH PRESSURE EDGING IN
FROM THE NORTHWEST. GIVEN THE STRONGER WINDS AND COOLER AIR SLIDING
IN...FREEZING SPRAY WILL BE POSSIBLE. HIGH PRESSURE WILL WIN OUT
FRIDAY...WITH A RIDGE RESIDING ACROSS LAKE SUPERIOR THROUGH AT LEAST
SATURDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...KC
MARINE...KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
358 AM EST TUE FEB 26 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM EST TUE FEB 26 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW PATTERN
ACRS NAMERICA...WITH THE UPR GRT LKS UNDER A POLAR JET STREAM WELL S
OF ARCTIC BRANCH IN CENTRL CANADA THAT HAS CONFINED THE BITTERLY
COLD ARCTIC AIR TO FAR NRN CANADA. AN ACTIVE SUBTROPICAL BRANCH
DOMINATES THE S HALF OF THE CONUS...WITH A POTENT DISTURBANCE MOVING
INTO THE LOWER-MID MS RIVER VALLEY. A DISTURBANCE WITHIN THE POLAR
BRANCH IS MOVING ACRS UPR MI EARLY THIS MRNG...BUT LIMITED MSTR
DEPTH PER 00Z GRB/APX RAOBS AND GENERAL LARGER SCALE ACYC FLOW
RELATED TO RDG AXIS EXTENDING WWD FM HI CENTER IN SE CANADA HAS
RESTRICTED ANY IMPACT TO AN AREA OF SC. THE BACK EDGE OF THIS CLD
AREA IS JUST INLAND FM THE W SHORE OF UPR MI CLOSER TO INCOMING AREA
OF DRY AIR DEPICTED ON THE 00Z INL/MPX RAOBS AND WHICH IS UNDER
DNVA/LARGE SCALE QVECTOR DVGC BEHIND THE SHRTWV. SKIES OVER FAR NW
WI/WRN LK SUP AND THE MN ARROWHEAD OF MOCLR...WHICH HAS ALLOWED SOME
FOG TO FORM WITH LGT WINDS. HI CLDS ON THE NRN EDGE OF THE
SUBTROPICAL BRANCH DISTURBANCE TO THE S ARE SPREADING SLOWLY NWD
THRU WI.
MAIN FCST CONCERNS TODAY ARE CLD TRENDS/IMPACT ON TEMPS. FOCUS FOR
TNGT SHIFTS TO WHETHER ANY PCPN ASSOCIATED WITH SRN BRANCH
DISTURBANCE WL IMPACT THE SRN CWA.
TODAY...POLAR BRANCH UPR RDG/DNVA/LARGE SCALE QVECTOR DVGC WL
DOMINATE UPR MI TODAY. AS THE SUBTROPICAL BRANCH SFC LO MOVES INTO
THE LOWER OH RIVER VALLEY BY 00Z WED...THE PRES GRADIENT WL TIGHTEN
OVER UPR MI TO THE WSW OF HI CENTERED IN SE CANADA...WITH AN INCRSG
ENE FLOW. ALTHOUGH THE LARGER SCALE NEGATIVE DYNAMICS WOULD INDICATE
A SLOW BREAKUP OF THE SC DOMINATAING MUCH OF THE CWA NOW...THIS LO
CLD IS WIDESPREAD TO THE E OF UPR MI THIS MRNG...THE SOURCE AIRMASS
FOR THE DVLPG E WIND. ON THE OTHER HAND...THE DIFFLUENT NATURE OF
THE LLVL FLOW AS WELL AS STRONG SUBSIDENCE FCST AT H925 SHOULD TEND
TO BREAK UP THE LO CLD. RECENT TRENDS SHOWN ON STLT IMAGERY/SFC OBS
CONFIRM THIS EXPECTATION. DIURNAL HEATING WITH INCRSG LATE FEB SUN
ANGLE WL ALSO TEND TO DISSIPATE THE SC OVER THE LAKES AS H85 TEMPS
ARE FCST TO BE ABOUT -4C...A TYPICAL EARLY SPRING SCENARIO. IN THIS
SCENARIO...SOME DIURNAL CU/SC WOULD TEND TO FORM OVER THE INTERIOR
FOLLOWING INITIAL CLRG. THE COVERAGE OF THIS CLD SHOULD BE LIMITED
BY THE RATHER LO INVRN BASE SHOWN ON NAM/GFS FCST SDNGS. MAINTAINED
OVERALL FLAVOR OF GOING FCST SHOWING A TERND FOR DECREASING CLDS
INTO THIS AFTN...WITH A BIT MORE CLD COVER OVER THE INTERIOR...
ESPECIALLY IN USPLOPE AREAS. MIXING TO H875 ON FCST SDNGS YIELDS HI
TEMPS CLOSE TO 40...MOST LIKELY IN AREAS OVER THE W THAT SEE MORE
SUNSHINE AND DOWNSLOPE IN LLVL ENE FLOW AWAY FM THE COOLING
INFLUENCE OF THE LKS. GOING FCST NEEDS ONLY MINOR ADJUSTMENTS.
TNGT...SUBTROPICAL BRANCH LO IS PROGGED TO MOVE NE INTO OH BY 12Z
WED. THE BULK OF THE NUMERICAL GUIDANCE SHOWS LGT QPF ON THE NW
FLANK OF THIS LO PRES BRUSHING JUST THE SE COUNTIES WITH SOME LGT
PCPN TOWARD 12Z WED...CONSISTENT WITH THE PASSAGE OF THE DEEP LYR
QVECTOR THRU LWR MI. DESPITE CYC NATURE OF THE INCRSG LLVL NE
FLOW...H85 TEMPS NO LOWER THAN ABOUT -5C AS WELL AS FCST DRY H85-7
LYR INDICATE THERE WL BE NO LK EFFECT/ENHANCED PCPN EVEN IF MORE SC
DVLPS IN THE UPSLOPE AREAS. OPTED TO RETAIN GOING SCHC POPS ONLY
CLOSE TO LK MI/BAY OF GREEN BAY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM EST TUE FEB 26 2013
NOT MUCH IN THE WAY OF PRECIPITATION EXPECTED THROUGH THIS LONG TERM
PERIOD...WITH MARCH LIKELY COMING IN LIKE A LAMB /AS NOTED ON THE
PREVIOUS DISCUSSION/.
BY WEDNESDAY THE 500MB LOW WILL BE THE CLOSEST IT WILL GET TO THE
CWA...TRACKING FROM OHIO TO NE PENNSYLVANIA...SQUEEZING THE RIDGE
NORTH INTO ONTARIO. EXPECT NE FLOW AT THE SFC AND ALOFT WEDNESDAY.
THE 25/12Z CONTINUES TO SHOW A SOUTHERLY TREND TO THE TRACK...WITH A
DOUBLE BARREL LOW SPLITTING THE APPALACHIANS MERGING ACROSS THE NEW
ENGLAND STATES WEDNESDAY NIGHT. A MEER 24 HOURS AGO THE NAM SOLUTION
WAS FOR THE SURFACE LOW TO SWING ACROSS CENTRAL LOWER MICHIGAN...NOW
IT LOOKS TO BE MORE IN LINE IF NOT SLIGHTLY SLOWER THAN THE
ECMWF/GFS ON WEDNESDAY.
STRONG HIGH PRESSURE STRETCHING ACROSS NORTH CENTRAL CANADA ON
TUESDAY WILL PUSH INTO HUDSON BAY AND MANITOBA/ONTARIO
WEDNESDAY/WEDNESDAY NIGHT...WITH THE RIDGE EDGING ACROSS LAKE
SUPERIOR THURSDAY NIGHT THROUGH AT LEAST SUNDAY MORNING. WE STILL
EXPECT SOME BREEZY CONDITIONS NEAR THE LAKE SUPERIOR SHORELINE
WEDNESDAY THROUGH THURSDAY /PUSHING ACROSS MUCH OF CENTRAL UPPER
MICHIGAN DURING THE DAY THURSDAY/. WINDS WILL SLOWLY DIMINISH AS THE
LOW CONTINUES TO EXIT EAST AND THE SURFACE HIGH PUSHES OVERHEAD.
AS FOR THE CHANCE OF PRECIPITATION THROUGH THE PERIOD...IT IS PRETTY
MINIMAL. THE SYNOPTIC SNOW WILL ONLY CLIP AREAS NEAR LAKE MICHIGAN
WEDNESDAY INTO WEDNESDAY EVENING. EVEN WITH THE FAVORABLE UPSLOPE
WINDS OFF LAKE SUPERIOR...TEMPERATURES AT AND ABOVE THE SURFACE WILL
BE MARGINAL TO SUPPORT ANY ACCUMULATING SNOW SHOWERS.
COLDER AIR WILL FINALLY COME IN FOR THE END OF THE WORK WEEK...WITH
850MB TEMPERATURES FALLING TO AROUND -11C FRIDAY AFTERNOON...AND -12
TO -14C FRIDAY NIGHT THROUGH AT LEAST SUNDAY /WITH N-NE WINDS
CONTINUING THROUGH SATURDAY/.
THE 25/12Z ECMWF KEEPS THE RIDGE IN PLACE THROUGH TUESDAY...BECOMING
OUT OF PHASE WITH THE 25/18Z GFS BY MONDAY NIGHT /STRONG 1044MB HIGH
OVER NORTHERN MANITOBA AND ONTARIO...COMPARED TO THE 1005MB LOW
ACROSS ONTARIO/. WHILE THE 26/00Z GFS DID COME IT SLIGHTLY BETTER
AGREEMENT...IT JUST CAN NOT BEAT THE RUN TO RUN CONSISTENCY BEING
SHOWN BY THE ECMWF. CUT BACK THE SLIGHT CHANCE POPS GIVEN WITH A
CONSENSUS OF THE MODELS FOR DAY 6/MONDAY TO RIGHT ALONG THE
WISCONSIN BORDER...MINIMIZING THE INFLUENCE OF THE 26/00Z GFS RUN ON
THE POPS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1224 AM EST TUE FEB 26 2013
MVFR CIGS AT KIWD AND KCMX SHOULD GIVE WAY TO SCT CLOUDS OVERNIGHT
WITH POSSIBLE DEVELOPMENT OF FOG AND MVFR TO IFR VSBY. KSAW SHOULD
STAY UNDER MVFR CLOUD DECK LONGER OVERNIGHT SO EVEN IF THERE IS SOME
PARTIAL CLEARING LATE TONIGHT...FOG SHOULDN`T BE THAT THICK. ONLY
EXPECT MVFR VSBY REDUCTION AT KSAW. EXPECT IMPROVING CONDITIONS ON
TUESDAY WITH A RETURN TO VFR CONDITIONS BY LATE MORNING/EARLY
AFTERNOON.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 357 AM EST TUE FEB 26 2013
A RIDGE OF HIGH PRESSURE ACROSS LAKE SUPERIOR WILL PUSH NORTHWARD
TODAY...IN ADVANCE OF WEAKENING LOW PRESSURE SLIDING FROM SOUTHERN
MISSOURI THIS MORNING TO FAR SOUTHEASTERN LOWER MICHIGAN AND OHIO
WEDNESDAY MORNING...AND EXITING ACROSS NEW YORK WEDNESDAY NIGHT. AS
A RESULT...EXPECT A TROUGH OVER LAKE SUPERIOR WITH STEADY N-NE WINDS
FROM MID AFTERNOON THROUGH THE REST OF THE WORK WEEK. THE STRONGEST
WINDS...WITH A FEW GUSTS NEARING 35KTS CAN BE EXPECTED WEDNESDAY
INTO THURSDAY AS LAKE SUPERIOR BECOMES PINNED BETWEEN THE LOW
PRESSURE SYSTEM TO OUR SOUTHEAST AND STRONG HIGH PRESSURE EDGING IN
FROM THE NORTHWEST. GIVEN THE STRONGER WINDS AND COOLER AIR SLIDING
IN...FREEZING SPRAY WILL BE POSSIBLE. HIGH PRESSURE WILL WIN OUT
FRIDAY...WITH A RIDGE RESIDING ACROSS LAKE SUPERIOR THROUGH AT LEAST
SATURDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...VOSS
MARINE...KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
258 AM EST TUE FEB 26 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 413 PM EST MON FEB 25 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A SPLIT FLOW PATTERN
ACROSS NAMERICA. IN THE SRN STREAM...A WELL-DEFINED MID LEVEL LOW
WAS OVER N TX. IN THE NRN STREAM...A SHORTWAVE TROF EXTENDS FROM
HUDSON BAY TO THE UPPER MISSISSIPPI VALLEY. SOME FLURRIES HAVE BEEN
NOTED IN WI TODAY IN AN AREA OF WEAK ISENTROPIC ASCENT. SOME OF
THOSE FLURRIES MAY HAVE SLIPPED INTO SCTNRL UPPER MI THIS AFTN
ALTHOUGH NO REPORTS HAVE BEEN NOTED. OTHERWISE...MOSTLY CLOUDY SKIES
HAVE BEEN THE RULE TODAY...THOUGH THERE WAS A PERIOD OF MOSTLY SUNNY
SKIES FOR A TIME EARLIER OVER THE FAR W AND NW.
ALTHOUGH THE SHORT TERM PORTION OF THE FCST WILL FEATURE TRANQUIL
WEATHER...CLOUDS AND TEMPS WILL OFFER SOME CHALLENGING ASPECTS TO
THE FCST. UNDER WEAK ISENTROPIC ASCENT...WILL MAINTAIN A MENTION OF
A FEW FLURRIES INTO THE EVENING HRS OVER THE SRN PORTION OF THE FCST
AREA. CLOUD FCST IS NOT CERTAIN AT ALL AND THAT OPENS THE DOOR TO
BIG TEMP BUST POTENTIAL TONIGHT. UNDER LIGHT SW FLOW INTO THE
EVENING...MULTI-LAYERED CLOUDS TO THE SW SHOULD AFFECT MUCH OF THE
FCST AREA. OVERNIGHT...LOW-LEVEL WIND FIELDS BECOME VERY LIGHT WITH
A TREND TO LIGHT EASTERLY LATE WHICH SUGGESTS LITTLE ADVECTION OF
DRIER AIR. THUS...IT WOULD SEEM THAT MUCH OF THE AREA WILL SEE
MOSTLY CLOUDY SKIES TONIGHT. HOWEVER...THE PROXIMITY OF CLEAR SKIES
JUST TO THE W SUGGESTS THE WRN FCST AREA MAY HAVE THE BEST SHOT OF
SEEING A PERIOD OF PARTLY CLOUDY AND POSSIBLY CLEAR SKIES TONIGHT.
ALL IN ALL...THERE IS VERY LOW CONFIDENCE ON SKY CONDITION THRU THE
NIGHT. WITH LIGHT/CALM WINDS AT THE SFC...TEMPS WILL FALL
SIGNIFICANTLY IN SOME AREAS IF SKIES BECOME CLEAR/PARTLY CLOUDY FOR
A TIME. THIS COULD ALSO LEAD TO SOME FOG DEVELOPMENT. AT THIS
POINT...WILL PLAY IT CONSERVATIVE UTILIZING A CONSENSUS APPROACH TO
TEMPS...BUT WILL GO WITH LOWEST MIN TEMPS OVER THE W (MID TEENS)
WHERE IT APPEARS THERE IS A BETTER SHOT OF SEEING LESS CLOUDS FOR AT
LEAST A PORTION OF THE NIGHT. COULD EASILY SEE TEMPS FALL INTO THE
SINGLE DIGITS IF ANY LOCATIONS END UP CLEAR FOR A FEW HRS.
E TO NE WINDS WILL DEVELOP TUE AS UPPER MI FALLS INTO THE NRN
PERIPHERY OF THE CIRCULATION AROUND SRN STREAM LOW. WINDS WILL BE
STRONGEST IN THE MENOMINEE AREA AS A STIFF NE WIND WILL BE THE RULE
IN THE AFTN DUE TO COASTAL CONVERGENCE/FUNNELING DOWN THE BAY.
STRATOCU SHOULD TEND TO BREAK UP AS MODELS SUGGEST SOME DRYING...
BUT THE LWR CLOUDS WILL PROBABLY HANG ON LONGEST WHERE EASTERLY
WINDS UPSLOPE. WHERE LOW CLOUDS SCATTER OUT OR CLEAR...THERE SHOULD
BE A FAIR AMOUNT OF SUNSHINE THRU ONLY SOME HIGH CLOUDS. EXPECT MAX
TEMPS IN THE 30S...COOLEST (LOW 30S) AT LOCATIONS WHERE WINDS ARE
OFF THE LAKES AND IN THE UPSLOPE AREAS. TEMPS COULD RISE TO NEAR 40
IN LOCATIONS THAT SEE DOWNSLOPING WITH EASTERLY WINDS.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 258 AM EST TUE FEB 26 2013
NOT MUCH IN THE WAY OF PRECIPITATION EXPECTED THROUGH THIS LONG TERM
PERIOD...WITH MARCH LIKELY COMING IN LIKE A LAMB /AS NOTED ON THE
PREVIOUS DISCUSSION/.
BY WEDNESDAY THE 500MB LOW WILL BE THE CLOSEST IT WILL GET TO THE
CWA...TRACKING FROM OHIO TO NE PENNSYLVANIA...SQUEEZING THE RIDGE
NORTH INTO ONTARIO. EXPECT NE FLOW AT THE SFC AND ALOFT WEDNESDAY.
THE 25/12Z CONTINUES TO SHOW A SOUTHERLY TREND TO THE TRACK...WITH A
DOUBLE BARREL LOW SPLITTING THE APPALACHIANS MERGING ACROSS THE NEW
ENGLAND STATES WEDNESDAY NIGHT. A MEER 24 HOURS AGO THE NAM SOLUTION
WAS FOR THE SURFACE LOW TO SWING ACROSS CENTRAL LOWER MICHIGAN...NOW
IT LOOKS TO BE MORE IN LINE IF NOT SLIGHTLY SLOWER THAN THE
ECMWF/GFS ON WEDNESDAY.
STRONG HIGH PRESSURE STRETCHING ACROSS NORTH CENTRAL CANADA ON
TUESDAY WILL PUSH INTO HUDSON BAY AND MANITOBA/ONTARIO
WEDNESDAY/WEDNESDAY NIGHT...WITH THE RIDGE EDGING ACROSS LAKE
SUPERIOR THURSDAY NIGHT THROUGH AT LEAST SUNDAY MORNING. WE STILL
EXPECT SOME BREEZY CONDITIONS NEAR THE LAKE SUPERIOR SHORELINE
WEDNESDAY THROUGH THURSDAY /PUSHING ACROSS MUCH OF CENTRAL UPPER
MICHIGAN DURING THE DAY THURSDAY/. WINDS WILL SLOWLY DIMINISH AS THE
LOW CONTINUES TO EXIT EAST AND THE SURFACE HIGH PUSHES OVERHEAD.
AS FOR THE CHANCE OF PRECIPITATION THROUGH THE PERIOD...IT IS PRETTY
MINIMAL. THE SYNOPTIC SNOW WILL ONLY CLIP AREAS NEAR LAKE MICHIGAN
WEDNESDAY INTO WEDNESDAY EVENING. EVEN WITH THE FAVORABLE UPSLOPE
WINDS OFF LAKE SUPERIOR...TEMPERATURES AT AND ABOVE THE SURFACE WILL
BE MARGINAL TO SUPPORT ANY ACCUMULATING SNOW SHOWERS.
COLDER AIR WILL FINALLY COME IN FOR THE END OF THE WORK WEEK...WITH
850MB TEMPERATURES FALLING TO AROUND -11C FRIDAY AFTERNOON...AND -12
TO -14C FRIDAY NIGHT THROUGH AT LEAST SUNDAY /WITH N-NE WINDS
CONTINUING THROUGH SATURDAY/.
THE 25/12Z ECMWF KEEPS THE RIDGE IN PLACE THROUGH TUESDAY...BECOMING
OUT OF PHASE WITH THE 25/18Z GFS BY MONDAY NIGHT /STRONG 1044MB HIGH
OVER NORTHERN MANITOBA AND ONTARIO...COMPARED TO THE 1005MB LOW
ACROSS ONTARIO/. WHILE THE 26/00Z GFS DID COME IT SLIGHTLY BETTER
AGREEMENT...IT JUST CAN NOT BEAT THE RUN TO RUN CONSISTENCY BEING
SHOWN BY THE ECMWF. CUT BACK THE SLIGHT CHANCE POPS GIVEN WITH A
CONSENSUS OF THE MODELS FOR DAY 6/MONDAY TO RIGHT ALONG THE
WISCONSIN BORDER...MINIMIZING THE INFLUENCE OF THE 26/00Z GFS RUN ON
THE POPS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1224 AM EST TUE FEB 26 2013
MVFR CIGS AT KIWD AND KCMX SHOULD GIVE WAY TO SCT CLOUDS OVERNIGHT
WITH POSSIBLE DEVELOPMENT OF FOG AND MVFR TO IFR VSBY. KSAW SHOULD
STAY UNDER MVFR CLOUD DECK LONGER OVERNIGHT SO EVEN IF THERE IS SOME
PARTIAL CLEARING LATE TONIGHT...FOG SHOULDN`T BE THAT THICK. ONLY
EXPECT MVFR VSBY REDUCTION AT KSAW. EXPECT IMPROVING CONDITIONS ON
TUESDAY WITH A RETURN TO VFR CONDITIONS BY LATE MORNING/EARLY
AFTERNOON.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 258 AM EST TUE FEB 26 2013
A RIDGE OF HIGH PRESSURE ACROSS LAKE SUPERIOR WILL PUSH NORTHWARD
TODAY...IN ADVANCE OF WEAKENING LOW PRESSURE SLIDING FROM SOUTHERN
MISSOURI THIS MORNING TO FAR SOUTHEASTERN LOWER MICHIGAN AND OHIO
WEDNESDAY MORNING...AND EXITING ACROSS NEW YORK WEDNESDAY NIGHT. AS
A RESULT...EXPECT A TROUGH OVER LAKE SUPERIOR WITH STEADY N-NE WINDS
FROM MID AFTERNOON THROUGH THE REST OF THE WORK WEEK. THE STRONGEST
WINDS...WITH A FEW GUSTS NEARING 35KTS CAN BE EXPECTED WEDNESDAY
INTO THURSDAY AS LAKE SUPERIOR BECOMES PINNED BETWEEN THE LOW
PRESSURE SYSTEM TO OUR SOUTHEAST AND STRONG HIGH PRESSURE EDGING IN
FROM THE NORTHWEST. GIVEN THE STRONGER WINDS AND COOLER AIR SLIDING
IN...FREEZING SPRAY WILL BE POSSIBLE. HIGH PRESSURE WILL WIN OUT
FRIDAY...WITH A RIDGE RESIDING ACROSS LAKE SUPERIOR THROUGH AT LEAST
SATURDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...VOSS
MARINE...KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1228 AM EST TUE FEB 26 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 413 PM EST MON FEB 25 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A SPLIT FLOW PATTERN
ACROSS NAMERICA. IN THE SRN STREAM...A WELL-DEFINED MID LEVEL LOW
WAS OVER N TX. IN THE NRN STREAM...A SHORTWAVE TROF EXTENDS FROM
HUDSON BAY TO THE UPPER MISSISSIPPI VALLEY. SOME FLURRIES HAVE BEEN
NOTED IN WI TODAY IN AN AREA OF WEAK ISENTROPIC ASCENT. SOME OF
THOSE FLURRIES MAY HAVE SLIPPED INTO SCTNRL UPPER MI THIS AFTN
ALTHOUGH NO REPORTS HAVE BEEN NOTED. OTHERWISE...MOSTLY CLOUDY SKIES
HAVE BEEN THE RULE TODAY...THOUGH THERE WAS A PERIOD OF MOSTLY SUNNY
SKIES FOR A TIME EARLIER OVER THE FAR W AND NW.
ALTHOUGH THE SHORT TERM PORTION OF THE FCST WILL FEATURE TRANQUIL
WEATHER...CLOUDS AND TEMPS WILL OFFER SOME CHALLENGING ASPECTS TO
THE FCST. UNDER WEAK ISENTROPIC ASCENT...WILL MAINTAIN A MENTION OF
A FEW FLURRIES INTO THE EVENING HRS OVER THE SRN PORTION OF THE FCST
AREA. CLOUD FCST IS NOT CERTAIN AT ALL AND THAT OPENS THE DOOR TO
BIG TEMP BUST POTENTIAL TONIGHT. UNDER LIGHT SW FLOW INTO THE
EVENING...MULTI-LAYERED CLOUDS TO THE SW SHOULD AFFECT MUCH OF THE
FCST AREA. OVERNIGHT...LOW-LEVEL WIND FIELDS BECOME VERY LIGHT WITH
A TREND TO LIGHT EASTERLY LATE WHICH SUGGESTS LITTLE ADVECTION OF
DRIER AIR. THUS...IT WOULD SEEM THAT MUCH OF THE AREA WILL SEE
MOSTLY CLOUDY SKIES TONIGHT. HOWEVER...THE PROXIMITY OF CLEAR SKIES
JUST TO THE W SUGGESTS THE WRN FCST AREA MAY HAVE THE BEST SHOT OF
SEEING A PERIOD OF PARTLY CLOUDY AND POSSIBLY CLEAR SKIES TONIGHT.
ALL IN ALL...THERE IS VERY LOW CONFIDENCE ON SKY CONDITION THRU THE
NIGHT. WITH LIGHT/CALM WINDS AT THE SFC...TEMPS WILL FALL
SIGNIFICANTLY IN SOME AREAS IF SKIES BECOME CLEAR/PARTLY CLOUDY FOR
A TIME. THIS COULD ALSO LEAD TO SOME FOG DEVELOPMENT. AT THIS
POINT...WILL PLAY IT CONSERVATIVE UTILIZING A CONSENSUS APPROACH TO
TEMPS...BUT WILL GO WITH LOWEST MIN TEMPS OVER THE W (MID TEENS)
WHERE IT APPEARS THERE IS A BETTER SHOT OF SEEING LESS CLOUDS FOR AT
LEAST A PORTION OF THE NIGHT. COULD EASILY SEE TEMPS FALL INTO THE
SINGLE DIGITS IF ANY LOCATIONS END UP CLEAR FOR A FEW HRS.
E TO NE WINDS WILL DEVELOP TUE AS UPPER MI FALLS INTO THE NRN
PERIPHERY OF THE CIRCULATION AROUND SRN STREAM LOW. WINDS WILL BE
STRONGEST IN THE MENOMINEE AREA AS A STIFF NE WIND WILL BE THE RULE
IN THE AFTN DUE TO COASTAL CONVERGENCE/FUNNELING DOWN THE BAY.
STRATOCU SHOULD TEND TO BREAK UP AS MODELS SUGGEST SOME DRYING...
BUT THE LWR CLOUDS WILL PROBABLY HANG ON LONGEST WHERE EASTERLY
WINDS UPSLOPE. WHERE LOW CLOUDS SCATTER OUT OR CLEAR...THERE SHOULD
BE A FAIR AMOUNT OF SUNSHINE THRU ONLY SOME HIGH CLOUDS. EXPECT MAX
TEMPS IN THE 30S...COOLEST (LOW 30S) AT LOCATIONS WHERE WINDS ARE
OFF THE LAKES AND IN THE UPSLOPE AREAS. TEMPS COULD RISE TO NEAR 40
IN LOCATIONS THAT SEE DOWNSLOPING WITH EASTERLY WINDS.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 413 PM EST MON FEB 25 2013
THREE SHORTWAVES WILL INFLUENCE THE WEATHER FOR MUCH OF THE EASTERN
HALF OF THE CONUS OVER THE NEXT SEVERAL DAYS AND SETUP THE WEATHER
PATTERN HEADING INTO THE FIRST WEEK OF MARCH.
THE FIRST WAVE IS CURRENTLY SPINNING IN THE SOUTHERN PLAINS AND WILL
EJECT TOWARDS THE LOWER GREAT LAKES ON TUESDAY INTO TUESDAY
NIGHT...WHILE THE NEXT WAVE DIVES SOUTHEAST ACROSS THE CENTRAL
ROCKIES. MODELS HAVE BECOME MUCH MORE CONSISTENT WITH THIS SYSTEM IN
THE LAST 24 HOURS...AS THERE WERE DIFFERENCES IN THE INTERACTION
BETWEEN THE FIRST AND SECOND WAVES...WITH THE MERGER AND NORTHWARD
EXTENT. EVERYTHING SEEMS TO HAVE COME INTO AGREEMENT WITH THE
CONSISTENT ECMWF ON A MORE SOUTHERN TRACK THAT JUST BRUSHES THE FAR
SOUTHEAST PART OF UPPER MICHIGAN /NEAR LAKE MICHIGAN/ WITH LIGHT
SNOW LATE TUESDAY NIGHT INTO WEDNESDAY EVENING. ANY SLIGHT
DIFFERENCES IN THE NORTHWEST EXTENT OF THE TRACK WILL NOT ONLY
AFFECT THE SNOW NEAR LAKE MICHIGAN...BUT ALSO THE POTENTIAL FOR
LIGHT LAKE ENHANCEMENT OR UPSLOPE PRECIPITATION WITH THE
NORTH-NORTHEAST FLOW AROUND THE LOW. WITH THE LIMITED COLD AIR IN
PLACE AT THIS TIME...IT LOOKS LIKE 850MB TEMPS ON WEDNESDAY ARE ONLY
AROUND -5C...SO DELTA-T VALUES ARE FAIRLY MARGINAL. WHEN COMBINING
THAT WITH LIMITED MOISTURE...UNLESS THE FARTHER NW 06Z NAM IS
CORRECT...WOULDN/T THINK AREAS AWAY FROM LAKE MICHIGAN WOULD SEE
MUCH MORE THAN LOW CLOUDS AND UPSLOPE FLURRIES OR LIGHT SNOW OVER
THE NORTH CENTRAL ON WEDNESDAY PENDING ENOUGH MOISTURE. MODELS ARE
IN BETTER AGREEMENT ON LOW LEVEL MOISTURE MOVING IN ON WEDNESDAY
NIGHT AS THE LOW SHIFTS EAST INTO NEW YORK. THIS IS IN RESPONSE TO
ADDITIONAL MOISTURE ASSOCIATED WITH A NORTHERN STREAM SHORTWAVE
MOVING THROUGH SOUTHERN CANADA. THIS WILL LIKELY LEAD TO THE BEST
POTENTIAL FOR PRECIPITATION FOR AREAS NEAR LAKE SUPERIOR WEDNESDAY
NIGHT INTO THURSDAY. 850MB TEMPS ARE STILL MARGINAL THROUGH THIS
PERIOD...BUT DO DROP TO -10C. WITH THE MARGINAL DELTA-T VALUES AND
AN INVERSION HEIGHT SITTING AROUND 4KFT...THINKING THAT THE LIGHT
SNOW SHOWERS WILL REMAIN IN THE NORTH-NORTHEAST FAVORED LOCATIONS OF
NORTHERN UPPER MICHIGAN. STRONGEST SHOWERS SHOULD OCCUR OVER THE
HIGHER TERRAIN OF NORTH CENTRAL UPPER MICHIGAN...WHERE UPSLOPE FLOW
WILL AID THE FORCING SOME. WILL CONTINUE TO MENTION SLIGHTS AND LOW
CHANCE POPS IN THESE AREAS INTO THURSDAY NIGHT.
MEANWHILE...THE THIRD MAIN SHORTWAVE WILL BE DIVING SOUTHEAST
THROUGH THE ROCKIES ON WEDNESDAY NIGHT AND THURSDAY AND AMPLIFY THE
UPPER TROUGH OVER THE EASTERN CONUS. THIS WILL LEAD THE UPPER GREAT
LAKES INTO A COLDER THAN NORMAL PERIOD FOR THE LAST DAY OF FEBRUARY
AND THE FIRST WEEK OF MARCH. WHILE THIS BRINGS GRADUALLY COLDER AIR
/925-900MB TEMPS FALLING TOWARDS -12 TO -14C/...IT WILL ALSO PUSH A
HIGH PRESSURE RIDGE OVER THE AREA FROM A HIGH CENTERED OVER HUDSON
BAY. THIS SUBSIDENCE WILL WORK TO LOWER THE INVERSION HEIGHTS BELOW
3KFT BY FRIDAY MORNING. THEREFORE...WOULD JUST EXPECT LINGERING
LOW CLOUDS AND AN ISOLATED SNOW SHOWER FOR FRIDAY INTO SATURDAY
OVER LOCATIONS NEAR LAKE SUPERIOR. THERE ARE SOME DIFFERENCES IN
THE WIND DIRECTION ROTATING AROUND THE HIGH...BUT WILL MAINLY FOCUS
THE SLIGHT CHANCES OVER THE NORTH CENTRAL.
DIFFERENCES ARRIVE HEADING INTO THE SECOND HALF OF THE WEEKEND WITH
THE HANDLING OF A SHORTWAVE DROPPING THROUGH ON THE BACK SIDE OF
THE RIDGE OVER THE WESTERN CONUS. THE 00Z ECMWF KEEPS THE RIDGE
FARTHER TO THE WEST BEHIND THE SHORTWAVE...WHILE THE 12Z GFS PUSHES
IT INTO THE UPPER GREAT LAKES. DEPENDING ON THE SOLUTION...THIS
WILL EITHER KEEP THE AREA UNDER THE SURFACE RIDGE INTO THE FIRST
PART OF NEXT WEEK OR HAVE THE AREA INFLUENCED BY THE NEXT CLIPPER
SYSTEM APPROACHING FOR MONDAY. WILL GO WITH THE PERSISTENT HIGH AND
DRIER SOLUTION INTO MONDAY.
AFTER A FAIRLY ACTIVE PERIOD FOR THE LAST COUPLE OF WEEKS OF
FEBRUARY...IT/S LOOKING LIKE MARCH WILL COME IN LIKE A LAMB FOR
MUCH OF THE UPPER GREAT LAKES REGION. FORTUNATELY...THIS ACTIVE
PERIOD BROUGHT THE AREA CLOSER TO NORMAL SNOWFALL...ALTHOUGH SOME
LOCATIONS ARE STILL BELOW NORMAL ON SNOWFALL /OUR OFFICE/ AND SNOW
WATER EQUIVALENT /MICHIGAMME RIVER BASIN/. BUT LOOKING AT MODEL RUN
QPF...THE NEXT 10 DAYS DON/T APPEAR TO BE TOO PROMISING FOR
ADDITIONS TO THE SNOW PACK. 00Z ECMWF ONLY SHOWS 10 DAY ACCUMULATION
OF 0.02-0.08 INCH FOR THE ENTIRE CWA. 00Z GFS FOR THE
SIMILAR PERIOD KEEPS VALUES UNDER 0.25 OF AN INCH...WITH MUCH OF
THAT COMING FROM THE SYSTEM BRUSHING THE AREA ON WEDNESDAY AND
THURSDAY. ON THE POSITIVE SIDE...THE EXISTING SNOWPACK WILL REMAIN
IN PLACE AS TEMPERATURES TREND TOWARDS A COOLER THAN NORMAL PERIOD
FOR THE AREA FRIDAY INTO THE NEXT WORK WEEK /HIGHS IN THE 20S AND
LOWS IN THE SINGLE DIGITS ABOVE ZERO/.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1224 AM EST TUE FEB 26 2013
MVFR CIGS AT KIWD AND KCMX SHOULD GIVE WAY TO SCT CLOUDS OVERNIGHT
WITH POSSIBLE DEVELOPMENT OF FOG AND MVFR TO IFR VSBY. KSAW SHOULD
STAY UNDER MVFR CLOUD DECK LONGER OVERNIGHT SO EVEN IF THERE IS SOME
PARTIAL CLEARING LATE TONIGHT...FOG SHOULDN`T BE THAT THICK. ONLY
EXPECT MVFR VSBY REDUCTION AT KSAW. EXPECT IMPROVING CONDITIONS ON
TUESDAY WITH A RETURN TO VFR CONDITIONS BY LATE MORNING/EARLY
AFTERNOON.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 413 PM EST MON FEB 25 2013
ALTHOUGH HIGH PRES WILL BE DEPARTING...WINDS WILL REMAIN UNDER 20KT
PROBABLY THRU TUE AFTN. THEREAFTER...TIGHTENING PRES GRADIENT BTWN
HIGH PRES TO THE N AND NW AND LOW PRES TRACKING THRU THE LOWER OHIO
VALLEY TO LOWER LAKES TUE/WED WILL RESULT IN NORTHEASTERLY WINDS
INCREASING TO 20-30KT TUE NIGHT THRU WED. MIGHT SEE A FEW GALE FORCE
GUSTS WED OVER THE E HALF. EVEN THOUGH THE LOW CONTINUES TO MOVE E
THU...THE HIGH BUILDING TOWARD THE AREA FROM N WILL MAINTAIN A TIGHT
PRES GRADIENT...RESULTING IN CONTINUED 20-30KT WINDS WITH SOME
GALE FORCE GUSTS POSSIBLE OVER THE E HALF. WINDS WILL THEN VERY
SLOWLY DIMINISH FROM W TO E FRI/SAT AS THE HIGH PRES MOVES CLOSER...
BUT IT WILL PROBABLY BE SAT BEFORE WINDS DROP BLO 20KT ACROSS THE
ENTIRE LAKE. ALONG WITH THE PERIOD OF STRONGER WINDS MID
WEEK...FREEZING SPRAY IS ALSO EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
233 PM CST TUE FEB 26 2013
.DISCUSSION...
INITIAL CONCERN IS CLOUD COVER OVERNIGHT. DRIER WEDGE IN LOWER
LEVEL CIRCULATING AROUND STORM TO THE SOUTH WAS STRONG ENOUGH THIS
AFTERNOON TO ERODE CLOUDS SOME. ANOTHER SURGE OF MOISTURE APPEARS
TO BE WORKING ACROSS THE UP AND NORTHEAST WI AND IS NOW MOVING
ACROSS WEST CENTRAL WI. LATEST RAP HAS THIS WORKING SOUTHWEST LATE
AFTERNOON INTO THE EVENING...AFFECTING MAINLY SOUTH CENTRAL MN.
STRATUS AND FOG IS NOW ERODING FROM THE NORTH AS WELL...IN DRIER
AIR FLOW OVER NORTHEAST MN. DIFFICULT TO DISCERN HOW FAR SOUTH
AND WEST THIS WILL GO. MODELS TREND MUCH DRIER IN THE 925-850MB
LAYER OVER THE WESTERN AREAS. STILL BELIEVE SIGNIFICANT AMOUNT OF
MID/HIGH CLOUDS WILL CONTINUE TO STREAM NORTH AND WEST OVER NIGHT
AND SHOULD MAINTAIN AT LEAST A MOSTLY CLOUDY SKY OVER MOST OF THE
AREA. FOG SHOULD BE LIMITED TO THE FAR WEST INTO THE EVENING...AND
SHOULDNT BECOME DENSE OR AS WIDESPREAD WITH THE GRADIENT
INCREASING AS WELL AS THE SURFACE WINDS OVERNIGHT.
CONCERN NUMBER TWO REMAINS HOW FAR NORTHWEST SNOW WILL DEVELOP
MAINLY DURING THE DAY WEDNESDAY. MODELS FAIRLY CONSISTENT ON
DRAGGING SNOW INTO FAR SOUTHEAST CWA...WITH THE NAM REMAINING THE
DRIEST. THE GFS IS FARTHER WEST INTO OUR CWA...WITH THE 12Z GEM
AND ECMWF CONFINING POSSIBILITY TO THE FAR SOUTHEAST CORNER OF THE
AREA. IT ALL HINGES ON HOW THE SECONDARY UPPER TROUGH MOVES ACROSS
KANSAS AND MERGES WITH THE UPPER LOW MOVING OVER THE OHIO RIVER
RIVER VALLEY. WILL CONTINUE THE TREND OF LOW END CHANCE POPS OVER
THAT REGION THROUGH WEDNESDAY.
SHOULD SEE SOME CLEARING INTO WEDNESDAY NIGHT FOLLOWING THE STORM
SYSTEM TO THE SOUTHEAST...BUT MODELS TREND ANOTHER SHORT WAVE
DROPPING SOUTHEAST OVER THE DAKOTAS AND MINNESOTA...THURSDAY INTO
FRIDAY. THIS SHOULD YIELD AT LEAST MORE CLOUDS AND THE THREAT OF
SOME FLURRIES...MAINLY OVER THE WESTERN AREAS. THE 12Z ECMWF IS
NOT AS AMPLIFIED WITH THIS FEATURE AND IS A BIT DRIER...SO WILL
LEAVE FLURRY MENTION OUT FOR NOW.
HIGH TEMPERATURES FORECAST SLIGHTLY BELOW NORMAL INTO THE
WEEKEND. NEXT STRONG TROUGH MOVES ASHORE ON THE WEST COAST OVER
THE WEEKEND. LONGER TERM MODELS BRINGING THIS NEXT WAVE/TROUGH
INTO THE AREA MAINLY SUNDAY NIGHT INTO TUESDAY. HAVE INCLUDED
SMALL CHANCE POPS FOR THIS FEATURE AS IT MOVES THROUGH THE AREA
FOR NOW. COULD BE WARM ENOUGH FOR A POSSIBLY MIX AS THE SYSTEM
WORKS INTO THE AREA...AT LEAST INITIALLY.
&&
.AVIATION.../18Z TAF ISSUANCE/
AREAS OF DENSE FOG HAS SLOWLY DISSIPATED ACROSS FAR WESTERN MN AS
OF 11 AM. ONLY COUNTIES ALONG THE SD HAVE VSBYS NEAR 1/4SM...BUT
OUTSIDE OF MPX TAF SITES. SHORT TERM CONCERNS DEAL WITH CIGS
RISING TO MVFR/VFR THIS AFTN... AND WHETHER THERE WILL BE ANOTHER
REPEAT OF THE DENSE FOG OVERNIGHT...ESPECIALLY FOR AXN.
PRESSURE GRADIENT HAS FINALLY INCREASED ENOUGH TO PRODUCE A
PREDOMINATE WIND DIRECTION FROM THE E/NE ACROSS MOST OF THE FA.
ONLY THE FAR NW HAS MORE INFLUENCE OF THE DEPARTING SFC RIDGE IN
NE MN. SATELLITE IMAGERY HAS NOTED THE DECREASING LOW CLDS IN THE
WEST WITH MORE MVFR CIGS ACROSS EC MN/WC WI. ANOTHER AREA OF MVFR
CIGS WAS NOTED ACROSS EASTERN WI...WHICH MAY INFLUENCE OR CAUSE
MORE MVFR CIGS IN WI/EC MN THIS EVENING. OTHERWISE...EXPECT A
BETTER AVIATION FORECAST IN TERMS OF HIGHER CIGS/VSBYS THAN IN THE
PREVIOUS 48 HRS AS THE PATTERN CHGS. EVEN SOME -SN IS POSSIBLE IN
EAU BY THE END OF THE TAF PERIOD. ONLY AXN HAS A CHC OF REPEATING
THE LIFR/VLIFR CIGS/VSBYS DURING THE OVERNIGHT HRS. WINDS WILL BE
GENERALLY FROM THE NE/ENE THIS AFTN ARND 6-12 KTS...THEN BEGIN TO
INCREASE AND SHIFT TO THE NNE/N BY MORNING...WITH GUSTY WINDS
DEVELOPING BY 15Z.
KMSP...
WILL CONTINUE THE SAME SCENARIO OF MVFR CIGS LIFTING BY 20Z...BUT
ENOUGH MOISTURE AND CONFIDENCE AFT 20Z IS LOW TO TOTALLY BRING IN
VFR. IN ADDITION...MORE MVFR CIGS ACROSS EASTERN WI MAY BEGIN TO
AFFECT THE AIRPORT TERMINAL AFT 2-4Z...WITH THE BEST TIME FRAME
TOWARD MIDNIGHT. THESE MVFR CIGS WILL LIKELY CONTINUE THRU MOST OF
THE TAF PERIOD WITH WINDS BECOMING MORE N/NNW WED MORNING...AND
GUSTY BY AFTN.
/OUTLOOK FOR KMSP/
THU...VFR WITH MVFR CIGS POSSIBLE. N WINDS AT 10KTS.
FRI...VFR WITH MVFR CIGS POSSIBLE. N WINDS AT 8KTS.
SAT...VFR. LIGHT N/NE WIND. ..JLT..
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
DWE/JLT
AREA FORECAST DISCUSSION
NWS DULUTH MN
1145 PM CST MON FEB 25 2013
.AVIATION...06Z TAFS
STRATUS WAS EXPANDING OVER THE BRAINERD LAKES/PINE RIVER AREA LATE
THIS EVENING. FOG WAS FORMING AS WELL...BUT ISN`T WIDESPREAD YET.
WE DO EXPECT THE FOG TO EXPAND AND BECOME DENSE IN SPOTS
OVERNIGHT. WE ALSO EXPECT THE MVFR CEILINGS OVER CENTRAL/NORTHERN
WISCONSIN TO EXPAND BACK TO THE NORTH AND WEST TONIGHT INTO
TUESDAY AS THE LOW LEVEL FLOW BECOMES EASTERLY. THE RAP13 LOW
LEVEL CONDENSATION PRESSURE DEFICITS HAD A DECENT HANDLE ON THESE
CEILINGS...AND ALSO SHOW EXPANSION TO THE WEST AND NORTH. WE
BROUGHT SOME OF THE CEILINGS INTO KDLH BY LATE TUESDAY MORNING.
&&
.PREV DISCUSSION... /ISSUED 801 PM CST MON FEB 25 2013/
UPDATE...
MAIN ISSUE IN THE SHORT TERM IS FOG POTENTIAL. CONCERN IS GROWING
THAT DENSE FOG WILL DEVELOP OVER PORTIONS OF OUR CWA. AT THIS
TIME WE ARE MOST CONCERNED WITH CASS COUNTY...EAST SOUTHEAST
TOWARD BURNETT COUNTY. TEMP-DEWPOINT SPREADS ARE LOW IN PARTS OF
THAT AREA...AND SKIES WERE CLEAR. WE`LL HAVE TO MONITOR ELSEWHERE
AS WELL. WE WILL WAIT ANOTHER HOUR OR SO...THEN DECIDE IF AND
WHERE WE WILL ISSUE A DENSE FOG ADVISORY.
PREV DISCUSSION... /ISSUED 550 PM CST MON FEB 25 2013/
AVIATION...00Z TAFS
SOME MVFR CEILINGS REMAINED OVER A PORTION OF NORTHWEST
WISCONSIN...AFFECTING KHYR/KASX/KPBH. SOME OF THE HIGH RES MODELS
SUGGEST THESE CEILINGS MAY DIMINISH SOME ON THE WEST EDGE...BUT
WILL REFORM OR ADVECT BACK TO THE WEST/NORTH AS THE LOW LEVEL FLOW
BECOMES EASTERLY. MORE LOWER CEILINGS WERE JUST SOUTHWEST OF
KBRD...AND THESE MAY REFORM LATER TONIGHT. THE RAP INDICATES THEY
WILL NOT...BUT CONFIDENCE THAT THESE CEILINGS WILL NOT REFORM IS
LOWER THAN AVERAGE.
FOG COULD BECOME AN ISSUE AS WELL OVERNIGHT WITH THE MILD TEMPS
MELTING SNOW TODAY. WE DID KEEP FOG IN ALL OF THE TAFS...AND
BROUGHT SOME IFR CEILINGS AS WELL. WE DID NOT GO TOO LOW ON VSBYS
YET...AND WILL WAIT UNTIL LATER TONIGHT AND SEE HOW THINGS DEVELOP
BEFORE MAKING ANY SIGNIFICANT CHANGES.
PREV DISCUSSION... /ISSUED 327 PM CST MON FEB 25 2013/
SHORT TERM...
THIS AFTERNOON THROUGH TUESDAY AFTERNOON...
QUIET WEATHER CONDITIONS ARE EXPECTED THROUGH THE SHORT TERM WITH
A WEAK RIDGE OF HIGH PRESSURE AT THE SFC IN PLACE ACROSS THE UPPER
MIDWEST. MAIN CONCERNS ARE FOCUSED AROUND TEMPERATURES AND THE
POTENTIAL FOR ANOTHER ROUND OF FOG TONIGHT...POSSIBLY DENSE IN
SOME LOCATIONS.
A WEAK UPPER TROUGH IS CURRENTLY MOVING THROUGH NRN MN/WRN LAKE
SUPERIOR THIS AFTERNOON AND DISSIPATING AS IT MOVES EWD. THERE WAS
A LINE OF LOW CLOUDS AND FLURRIES ASSOCIATED WITH A VERY WEAK SFC
TROUGH OVER NW MN THIS MORNING. HOWEVER...AS THE TROUGH HAS MOVED
EWD INTO THE DRIER AIR UNDER THE RIDGE...IT HAS WEAKENED
SUBSTANTIALLY THROUGH THE AFTERNOON. MOST OF THE CLOUD COVER HAS
DISSIPATED...AND LEFT ALMOST THE ENTIRE NORTHLAND UNDER MOSTLY
SUNNY SKIES THIS AFTERNOON. THERE IS ALSO AN AREA OF LOW/MID LEVEL
CLOUDS IN NW WI...THAT WILL ATTEMPT TO MOVE EWD...BUT BE REPLACED
QUICKLY BY ADDITIONAL CLOUDS MOVING IN FROM THE SOUTH ASSOCIATED
WITH THE LARGE WINTER STORM OVER THE CENTRAL PLAINS.
THE CLEAR SKIES TODAY HAVE LEAD TO TEMPERATURES REACHING INTO THE
MID TO UPPER 30S. ADDITIONAL TOP LAYER SNOW MELT LIKELY OCCURRED
ONCE AGAIN TODAY. SO...WITH THE CLEAR SKIES TONIGHT ALLOWING
TEMPERATURES TO FALL INTO THE TEENS...INCREASED LOW LEVEL
MOISTURE...LIGHT WINDS...AND A STRONG INVERSION ALOFT. THE THREAT
FOR FOG...POSSIBLY DENSE IN SOME LOCATIONS EXISTS AGAIN TONIGHT.
THE MOST FAVORABLE AREA FOR FOG APPEARS TO BE OVER NE MN...WITH
LIGHTER WINDS AND MOVE CLEARING. WHILE MUCH OF NW WI IS EXPECTED
TO REMAIN UNDER THE INFLUENCE OF MID/HIGH LEVEL CLOUDS AND
STRONGER MIXING.
TUESDAY IS EXPECTED TO BE ANOTHER PLEASANT DAY WITH MOSTLY SUNNY
TO PARTLY CLOUDY SKIES AFTER THE FOG BURNS OFF IN THE
MORNING...LIGHT WINDS AND TEMPERATURES IN THE MID TO UPPER
30S...POSSIBLY CLOSE TO 40 IN A FEW LOCATIONS.
LONG TERM...
TUESDAY NIGHT THROUGH MONDAY...
SOME LAKE EFFECT SNOW SHOWERS WILL LIKELY BE ONGOING ACROSS
NORTHERN PORTIONS OF WISCONSIN TUESDAY NIGHT AND INTO
WEDNESDAY...AS NORTHEAST WINDS BLOW ACROSS LAKE SUPERIOR FOR LONG
FETCH SNOW BANDS TO DEVELOP. AN INTENSE WINTER STORM WILL BE
ONGOING SOUTHEAST OF THE CWA WITH HIGH PRESSURE GENERALLY IN
CONTROL ACROSS OUR CWA. A TROUGH WILL LIKELY DEVELOP FROM THE LOW
PRESSURE SYSTEM MOVING THROUGH THE GREAT LAKES...WHICH MAY
ULTIMATELY BRING SOME BOUTS OF CLOUDINESS FOR THE REST OF THE WORK
WEEK...BUT IT WILL HAVE TO BATTLE UPPER LEVEL RIDGING AND HIGH
PRESSURE AS WELL. OVERALL IT LOOKS GENERALLY DRY FOR THE EXTENDED
TIME PERIOD AND WITH HIGHS IN THE UPPER 20S TO LOWER 30S. DAYTIME
MELTING MAY ALSO RESULT IN SOME FOG AT TIMES.
&&
.POINT TEMPS/POPS...
DLH 11 37 20 35 / 10 0 10 10
INL 10 38 14 34 / 0 0 0 10
BRD 7 35 18 35 / 10 0 0 0
HYR 8 37 20 36 / 10 10 20 20
ASX 13 34 23 34 / 10 0 20 30
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...DENSE FOG ADVISORY UNTIL 9 AM CST TUESDAY FOR MNZ025-033>036-038.
WI...DENSE FOG ADVISORY UNTIL 9 AM CST TUESDAY FOR WIZ006.
&&
$$
SHORT TERM...MELDE
LONG TERM....DAP
AVIATION...MELDE
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
1015 PM CST MON FEB 25 2013
.UPDATE...ADDED A FEW MORE COUNTIES TO THE DENSE FOG ADVISORY WITH
VISIBILITIES DETERIORATING TO THE SOUTH OF METRO. DID NOT WANT TO
LEAVE THE TWIN CITIES AS AN ISLAND IN THE ADVISORY. OUR LOCAL
HOPWRF AND HRRR WOULD SUGGEST LOWERING CONDITIONS IN THE HEART OF
THE TWIN CITIES AFTER 3 AM.
&&
.DISCUSSION... /ISSUED AT 303 PM CST MON FEB 25 2013/
A RATHER BENIGN FORECAST PERIOD IS AHEAD FOR THE LOCAL AREA...AS
EYES ARE FOCUSED TO THE SOUTH WITH THE POTENT WINTER STORM
UNDERWAY. FOR THE MPX CWA...THE PRIMARY CONCERNS THIS FORECAST
PERIOD ARE FOG TONIGHT AND SNOWFALL CHANCES FOR TOMORROW NIGHT
INTO WEDNESDAY.
FOG AND LOW CLOUDS HAVE BEEN VERY SLOW TO ERODE TODAY...WITH THE
LIGHT WINDS AND LOITERING HIGH PRESSURE RIDGE FIRMLY IN PLACE.
HAVE FINALLY MADE SOME HEADWAY IN THE CLEARING THIS
AFTERNOON...BUT THINK FOG REDEVELOPMENT IS QUITE POSSIBLE AGAIN
TONIGHT...ESPECIALLY FROM CENTRAL INTO WEST CENTRAL MN WHERE
TEMP/DEWPOINT SPREADS ARE LOW AND WINDS WILL REMAIN LIGHT THROUGH
THE NIGHT. HAVE HIGHLIGHTED THE POTENTIAL FOR PATCHY DENSE FOG IN
THE HWO AND GRIDS...AND WILL MONITOR FOR THE POTENTIAL NEED FOR AN
ADVISORY THIS EVENING AS THE CLEARING EVOLVES.
ON TUESDAY...NORTHEAST WINDS INCREASE AS THE AFOREMENTIONED LOW
PRESSURE SYSTEM LIFTS ACROSS THE OH VALLEY. ON TUESDAY NIGHT INTO
WEDNESDAY...WEAK MID LEVEL ENERGY ON THE NORTHERN/WESTERN
PERIPHERY PIVOTS ACROSS CENTRAL WI AND SERN MN. WHILE THE LIFT AND
MOISTURE ARE MODEST...COULD BE SUFFICIENT TO SQUEEZE OUT A FEW
TENTHS OF AN INCH OF SNOW FROM NEAR ALBERT LEA TOWARD EAU
CLAIRE...WHERE SLIGHT CHANCE POPS HAVE BEEN INCLUDED FOR TUESDAY
NIGHT AND WEDNESDAY.
AFTER THAT...CHANCES FOR MEASURABLE SNOW REALLY DO NOT ARRIVE
UNTIL EARLY NEXT WEEK...AS A CLIPPER SYSTEM DIVES SOUTHEAST FROM
CANADA. THERE/S STILL A LARGE AMOUNT OF UNCERTAINTY WITH THE ROUTE
THIS TROUGH WILL TAKE...BUT WESTERN INTO SOUTH CENTRAL MN APPEARS
TO BE THE MORE FAVORED ROUTE FOR LIGHT SNOWFALL ON MONDAY INTO
TUESDAY.
TEMPERATURES WILL VARY LITTLE THROUGH THE FORECAST PERIOD...WITH
HIGHS GENERALLY FROM 25 TO 35...AND LOWS FROM 10 TO 25.
&&
.AVIATION... /00Z TAF ISSUANCE/
CLOUDS AND FOG CONTINUE TO BE THE MAIN ISSUES. MVFR/IFR CLOUDS
STRADDLING THE EAST/WEST MINNESOTA BORDERS SHOULD FILL IN AGAIN
TONIGHT...WITH LIFR/VLIFR FOG EXPECTED ACROSS THE MINNESOTA RIVER
VALLEY. NNE WINDS WILL INCREASE ACROSS WESTERN WI AND SOUTHEASTERN
MN ON TUESDAY...WITH A GRADUAL IMPROVEMENT DURING THE AFTERNOON.
KMSP...
VFR CONDITIONS SHOULD LAST FOR THE NEXT FEW HOURS BEFORE MVFR
CIGS/VISBYS SPREAD ACROSS THE REGION TONIGHT. AT THIS TIME NOT
ANTICIPATING DROPPING BELOW 1700FT OR 4SM. LIGHT WINDS WILL
GRADUALLY BECOME NNE BY MORNING.
/OUTLOOK FOR KMSP/
WED...MVFR EARLY...THEN VFR. WINDS NNW AT 10G15KTS.
THU...VFR WITH MVFR CIGS POSSIBLE. WINDS N AT 5G10KTS.
FRI...VFR WITH MVFR CIGS POSSIBLE. WINDS N AT 10G15KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...DENSE FOG ADVISORY UNTIL 9 AM CST TUESDAY FOR ANOKA-BENTON-BLUE
EARTH-BROWN-CARVER-CHIPPEWA-CHISAGO-DAKOTA-DOUGLAS-GOODHUE-
HENNEPIN-ISANTI-KANABEC-KANDIYOHI-LAC QUI PARLE-LE SUEUR-
MCLEOD-MEEKER-MILLE LACS-MORRISON-NICOLLET-POPE-RAMSEY-
REDWOOD-RENVILLE-RICE-SCOTT-SHERBURNE-SIBLEY-STEARNS-STEELE-
STEVENS-SWIFT-TODD-WASECA-WASHINGTON-WRIGHT-YELLOW MEDICINE.
WI...DENSE FOG ADVISORY UNTIL 9 AM CST TUESDAY FOR PIERCE-POLK-ST.
CROIX.
&&
$$
RAH/LS/JLB
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1112 AM CST Tue Feb 26 2013
...UPDATED AVIATION DISCUSSION...
.UPDATE...
/901 AM CST Tue Feb 26 2013/
Have adjusted POPs based on latest radar trends. The storm seems to
have peaked and we are currently seeing dry air entrain into the
system from east, associated with the dry slot. This led to more
spotty precipitation in our eastern zones. So pops have been
decreased some there for the rest of the day. The main deformation
area is rotating through western and northwestern Missouri. This
should continue to be the case through the early afternoon so have
increased precipitation chances in that area. The IR satellite
depiction shows cloud tops have been warming which indicates a
weakening trend in the storm. This has led to radar returns
diminishing in intensity as well. Overall, the heaviest snow over the
next several hours will be across our northwestern zones from Kansas
City northward.
.DISCUSSION...
/400 AM CST Tue Feb 26 2013/
Today and Wednesday...
The ongoing winter storm continues to be the main focus for this
forecast issuance. Primary changes to the forecast are to increase
snow amounts in north central and northeast Missouri into the 10-12
inch range, with locally higher amounts possible. Snow totals have
also decreased across northwest Missouri, where snow may not start
until after sunrise and only a few inches of snow accumulation are
expected later this morning.
The deformation zone along the northeast side of a deepening surface
low has set up across the southeastern half of the forecast area,
and appears to be pivoting along a line from the southern KC metro
to Kirksville. The highest snowfall totals should occur within this
band and areas to the southeast, although melting and compaction may
work to decrease overall totals across the area. By 12z-15z, the
main PV anomaly will begin to kick east of the CWA, separating the
upper-level forcing from low- to mid-level frontogenesis and thus
likely decreasing snowfall rates/intensity by mid-morning. However,
at least some lift will linger in the trowal and support continued
light to moderate snowfall, especially over northeast and north
central Missouri. The RAP and latest NAM indicate that as the trowal
pivots northward this morning, light snowfall may finally edge into
the northwest corner of the CWA. Dynamics may start to weaken by the
time snowfall can start in the northwest and residence time over the
area will be much shorter, keeping snowfall totals in the 1-3 inch
range along and northwest of a line from St. Joseph to Sheridan MO.
A secondary wave will drop east southeast into southern portions of
the forecast area by late tonight, allowing some additional light
snowfall to form over northeast Kansas and west central Missouri.
This wave will wrap into the main upper low on Wednesday, allowing
light snowfall to shift eastward and eventually exit the region on
Wednesday afternoon. Additional snowfall amounts should be around an
inch or less, due to some depletion of low-level moisture and a lack
of any mesoscale features to enhance the weaker, broad-scale upper
forcing.
Temperatures today should be relatively steady throughout the day
and evening, dropping only a few degrees by tonight as slightly
cooler air filters in behind the low. Highs on Wednesday may rise a
few degrees in the northwest where a few breaks of sunshine and
lesser snow cover may allow for a bit more warming, but should hover
near freezing across the remainder of the area.
Laflin
Wednesday Night and Thursday...
The deep upper low responsible for our Tuesday winter storm will
have moved into the Mid Atlantic States during this period pulling
the extensive cloud shield with it. This should lead to at least a
partial clearing from west to east on Thursday. Temperatures will
remain below average as pronounced northerly fetch with weak high
pressure builds into the central CONUS.
Medium Range (Friday through Monday)...
The upper pattern will be characterized by a pronounced upper ridge
building eastward across the Rockies with a deepening trough over
from the TN into the Lower MS Valley. In between dry northwest flow
aloft will maintain well below average temperatures through Sunday.
Prefer to use the GFS Ensemble Mean h5 field for early next week due
to timing/evolution differences between the ECMWF and GFS of a fairly
strong upper wave dropping southeast through the Intermountain
Region Sunday night. This feature could reach the Central High
Plains on Monday with increasing warm air advection aiding
development of downstream precipitation which could affect the CWA
by Monday night. For now a model average works best with a moderate
increase in PoPs for Monday night.
MJ
&&
.AVIATION...
For the 18Z TAFs, conditions are beginning to improve at the terminals
with the main deformation band continuing to weaken and drift
westward. There may be some light snow showers move through the KC
terminals but any impact would be short-lived and minor. Otherwise
conditions may improve to MVFR late this afternoon. Another, weaker
system will move through the region tonight and will bring another
round of light to possibly moderate snow to the area. Have trended
back to IFR cigs for this snow but given what will be a much
lighter snow event have only reduced vsby to 1 to 2 miles. This snow
should move east of terminals mid Wednesday morning with conditions
then improving through the last few hours of the forecast.
CDB
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING until 3 PM CST this afternoon FOR MOZ004-
012>014-020>022-028>031-037>039-043>046-053-054.
WINTER STORM WARNING until 9 PM CST this evening FOR MOZ005>008-
015>017-023>025-032-033-040.
WINTER WEATHER ADVISORY until 3 PM CST this afternoon FOR
MOZ001>003-011.
KS...WINTER STORM WARNING until 3 PM CST this afternoon FOR KSZ025-
057-060-102>105.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
908 AM CST Tue Feb 26 2013
.UPDATE...
/901 AM CST Tue Feb 26 2013/
Have adjusted POPs based on latest radar trends. The storm seems to
have peaked and we are currently seeing dry air entrain into the
system from east, associated with the dry slot. This led to more
spotty precipitation in our eastern zones. So pops have been
decreased some there for the rest of the day. The main deformation
area is rotating through western and northwestern Missouri. This
should continue to be the case through the early afternoon so have
increased precipitation chances in that area. The IR satellite
depiction shows cloud tops have been warming which indicates a
weakening trend in the storm. This has led to radar returns
diminishing in intensity as well. Overall, the heaviest snow over the
next several hours will be across our northwestern zones from Kansas
City northward.
CDB
&&
.DISCUSSION...
Today and Wednesday...
The ongoing winter storm continues to be the main focus for this
forecast issuance. Primary changes to the forecast are to increase
snow amounts in north central and northeast Missouri into the 10-12
inch range, with locally higher amounts possible. Snow totals have
also decreased across northwest Missouri, where snow may not start
until after sunrise and only a few inches of snow accumulation are
expected later this morning.
The deformation zone along the northeast side of a deepening surface
low has set up across the southeastern half of the forecast area,
and appears to be pivoting along a line from the southern KC metro
to Kirksville. The highest snowfall totals should occur within this
band and areas to the southeast, although melting and compaction may
work to decrease overall totals across the area. By 12z-15z, the
main PV anomaly will begin to kick east of the CWA, separating the
upper-level forcing from low- to mid-level frontogenesis and thus
likely decreasing snowfall rates/intensity by mid-morning. However,
at least some lift will linger in the trowal and support continued
light to moderate snowfall, especially over northeast and north
central Missouri. The RAP and latest NAM indicate that as the trowal
pivots northward this morning, light snowfall may finally edge into
the northwest corner of the CWA. Dynamics may start to weaken by the
time snowfall can start in the northwest and residence time over the
area will be much shorter, keeping snowfall totals in the 1-3 inch
range along and northwest of a line from St. Joseph to Sheridan MO.
A secondary wave will drop east southeast into southern portions of
the forecast area by late tonight, allowing some additional light
snowfall to form over northeast Kansas and west central Missouri.
This wave will wrap into the main upper low on Wednesday, allowing
light snowfall to shift eastward and eventually exit the region on
Wednesday afternoon. Additional snowfall amounts should be around an
inch or less, due to some depletion of low-level moisture and a lack
of any mesoscale features to enhance the weaker, broad-scale upper
forcing.
Temperatures today should be relatively steady throughout the day
and evening, dropping only a few degrees by tonight as slightly
cooler air filters in behind the low. Highs on Wednesday may rise a
few degrees in the northwest where a few breaks of sunshine and
lesser snow cover may allow for a bit more warming, but should hover
near freezing across the remainder of the area.
Laflin
Wednesday Night and Thursday...
The deep upper low responsible for our Tuesday winter storm will
have moved into the Mid Atlantic States during this period pulling
the extensive cloud shield with it. This should lead to at least a
partial clearing from west to east on Thursday. Temperatures will
remain below average as pronounced northerly fetch with weak high
pressure builds into the central CONUS.
Medium Range (Friday through Monday)...
The upper pattern will be characterized by a pronounced upper ridge
building eastward across the Rockies with a deepening trough over
from the TN into the Lower MS Valley. In between dry northwest flow
aloft will maintain well below average temperatures through Sunday.
Prefer to use the GFS Ensemble Mean h5 field for early next week due
to timing/evolution differences between the ECMWF and GFS of a fairly
strong upper wave dropping southeast through the Intermountain
Region Sunday night. This feature could reach the Central High
Plains on Monday with increasing warm air advection aiding
development of downstream precipitation which could affect the CWA
by Monday night. For now a model average works best with a moderate
increase in PoPs for Monday night.
MJ
&&
.AVIATION...
For the 12z TAFs: A band of moderate to heavy snow will continue to
pivot northward across the region this morning, resulting in LIFR
visibilities and IFR to LIFR ceilings. The snowfall intensity should
decline from southeast to northwest from late morning through the
early afternoon, gradually improving visibilities into the MVFR
category; however, ceilings will likely remain IFR through much of
the day. Winds will be gusty out of the north northwest through the
early afternoon, then will decrease gradually through the evening
and overnight hours.
Laflin
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING until 3 PM CST this afternoon FOR MOZ004-
012>014-020>022-028>031-037>039-043>046-053-054.
WINTER STORM WARNING until 9 PM CST this evening FOR MOZ005>008-
015>017-023>025-032-033-040.
WINTER WEATHER ADVISORY until 3 PM CST this afternoon FOR
MOZ001>003-011.
KS...WINTER STORM WARNING until 3 PM CST this afternoon FOR KSZ025-
057-060-102>105.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
644 AM CST Tue Feb 26 2013
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
Today and Wednesday...
The ongoing winter storm continues to be the main focus for this
forecast issuance. Primary changes to the forecast are to increase
snow amounts in north central and northeast Missouri into the 10-12
inch range, with locally higher amounts possible. Snow totals have
also decreased across northwest Missouri, where snow may not start
until after sunrise and only a few inches of snow accumulation are
expected later this morning.
The deformation zone along the northeast side of a deepening surface
low has set up across the southeastern half of the forecast area,
and appears to be pivoting along a line from the southern KC metro
to Kirksville. The highest snowfall totals should occur within this
band and areas to the southeast, although melting and compaction may
work to decrease overall totals across the area. By 12z-15z, the
main PV anomaly will begin to kick east of the CWA, separating the
upper-level forcing from low- to mid-level frontogenesis and thus
likely decreasing snowfall rates/intensity by mid-morning. However,
at least some lift will linger in the trowal and support continued
light to moderate snowfall, especially over northeast and north
central Missouri. The RAP and latest NAM indicate that as the trowal
pivots northward this morning, light snowfall may finally edge into
the northwest corner of the CWA. Dynamics may start to weaken by the
time snowfall can start in the northwest and residence time over the
area will be much shorter, keeping snowfall totals in the 1-3 inch
range along and northwest of a line from St. Joseph to Sheridan MO.
A secondary wave will drop east southeast into southern portions of
the forecast area by late tonight, allowing some additional light
snowfall to form over northeast Kansas and west central Missouri.
This wave will wrap into the main upper low on Wednesday, allowing
light snowfall to shift eastward and eventually exit the region on
Wednesday afternoon. Additional snowfall amounts should be around an
inch or less, due to some depletion of low-level moisture and a lack
of any mesoscale features to enhance the weaker, broad-scale upper
forcing.
Temperatures today should be relatively steady throughout the day
and evening, dropping only a few degrees by tonight as slightly
cooler air filters in behind the low. Highs on Wednesday may rise a
few degrees in the northwest where a few breaks of sunshine and
lesser snow cover may allow for a bit more warming, but should hover
near freezing across the remainder of the area.
Laflin
Wednesday Night and Thursday...
The deep upper low responsible for our Tuesday winter storm will
have moved into the Mid Atlantic States during this period pulling
the extensive cloud shield with it. This should lead to at least a
partial clearing from west to east on Thursday. Temperatures will
remain below average as pronounced northerly fetch with weak high
pressure builds into the central CONUS.
Medium Range (Friday through Monday)...
The upper pattern will be characterized by a pronounced upper ridge
building eastward across the Rockies with a deepening trough over
from the TN into the Lower MS Valley. In between dry northwest flow
aloft will maintain well below average temperatures through Sunday.
Prefer to use the GFS Ensemble Mean h5 field for early next week due
to timing/evolution differences between the ECMWF and GFS of a fairly
strong upper wave dropping southeast through the Intermountain
Region Sunday night. This feature could reach the Central High
Plains on Monday with increasing warm air advection aiding
development of downstream precipitation which could affect the CWA
by Monday night. For now a model average works best with a moderate
increase in PoPs for Monday night.
MJ
&&
.AVIATION...
For the 12z TAFs: A band of moderate to heavy snow will continue to
pivot northward across the region this morning, resulting in LIFR
visibilities and IFR to LIFR ceilings. The snowfall intensity should
decline from southeast to northwest from late morning through the
early afternoon, gradually improving visibilities into the MVFR
category; however, ceilings will likely remain IFR through much of
the day. Winds will be gusty out of the north northwest through the
early afternoon, then will decrease gradually through the evening
and overnight hours.
Laflin
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING until 3 PM CST this afternoon FOR MOZ004-
012>014-020>022-028>031-037>039-043>046-053-054.
WINTER STORM WARNING until 9 PM CST this evening FOR MOZ005>008-
015>017-023>025-032-033-040.
WINTER WEATHER ADVISORY until 3 PM CST this afternoon FOR
MOZ001>003-011.
KS...WINTER STORM WARNING until 3 PM CST this afternoon FOR KSZ025-
057-060-102>105.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
400 AM CST Tue Feb 26 2013
.DISCUSSION...
Today and Wednesday...
The ongoing winter storm continues to be the main focus for this
forecast issuance. Primary changes to the forecast are to increase
snow amounts in north central and northeast Missouri into the 10-12
inch range, with locally higher amounts possible. Snow totals have
also decreased across northwest Missouri, where snow may not start
until after sunrise and only a few inches of snow accumulation are
expected later this morning.
The deformation zone along the northeast side of a deepening surface
low has set up across the southeastern half of the forecast area,
and appears to be pivoting along a line from the southern KC metro
to Kirksville. The highest snowfall totals should occur within this
band and areas to the southeast, although melting and compaction may
work to decrease overall totals across the area. By 12z-15z, the
main PV anomaly will begin to kick east of the CWA, separating the
upper-level forcing from low- to mid-level frontogenesis and thus
likely decreasing snowfall rates/intensity by mid-morning. However,
at least some lift will linger in the trowal and support continued
light to moderate snowfall, especially over northeast and north
central Missouri. The RAP and latest NAM indicate that as the trowal
pivots northward this morning, light snowfall may finally edge into
the northwest corner of the CWA. Dynamics may start to weaken by the
time snowfall can start in the northwest and residence time over the
area will be much shorter, keeping snowfall totals in the 1-3 inch
range along and northwest of a line from St. Joseph to Sheridan MO.
A secondary wave will drop east southeast into southern portions of
the forecast area by late tonight, allowing some additional light
snowfall to form over northeast Kansas and west central Missouri.
This wave will wrap into the main upper low on Wednesday, allowing
light snowfall to shift eastward and eventually exit the region on
Wednesday afternoon. Additional snowfall amounts should be around an
inch or less, due to some depletion of low-level moisture and a lack
of any mesoscale features to enhance the weaker, broad-scale upper
forcing.
Temperatures today should be relatively steady throughout the day
and evening, dropping only a few degrees by tonight as slightly
cooler air filters in behind the low. Highs on Wednesday may rise a
few degrees in the northwest where a few breaks of sunshine and
lesser snow cover may allow for a bit more warming, but should hover
near freezing across the remainder of the area.
Laflin
Wednesday Night and Thursday...
The deep upper low responsible for our Tuesday winter storm will
have moved into the Mid Atlantic States during this period pulling
the extensive cloud shield with it. This should lead to at least a
partial clearing from west to east on Thursday. Temperatures will
remain below average as pronounced northerly fetch with weak high
pressure builds into the central CONUS.
Medium Range (Friday through Monday)...
The upper pattern will be characterized by a pronounced upper ridge
building eastward across the Rockies with a deepening trough over
from the TN into the Lower MS Valley. In between dry northwest flow
aloft will maintain well below average temperatures through Sunday.
Prefer to use the GFS Ensemble Mean h5 field for early next week due
to timing/evolution differences between the ECMWF and GFS of a fairly
strong upper wave dropping southeast through the Intermountain
Region Sunday night. This feature could reach the Central High
Plains on Monday with increasing warm air advection aiding
development of downstream precipitation which could affect the CWA
by Monday night. For now a model average works best with a moderate
increase in PoPs for Monday night.
MJ
&&
.AVIATION...
For the 06Z TAFs...IFR cigs/vis with light snow has moved into MCI
and MKC (will reach STJ by 08Z) and will persist through tomorrow
afternoon. The heaviest snow will come down during the early morning
hours at the terminals with vsbys occasionally reduced to a quarter
of a mile or less with LIFR and occasional VLIFR cigs. Snowfall
rates at times will be on order of 1-2+ inches thus making it
difficult to keep runways clear. Conds will improve somewhat by mid
morning when snow will become light and vsby improve to 2-3SM
however cigs will remain IFR through the afternoon. Snow will come
to an end tomorrow evening with IFR cigs continuing.
73
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING until 3 PM CST this afternoon FOR MOZ004-
012>014-020>022-028>031-037>039-043>046-053-054.
WINTER STORM WARNING until 9 PM CST this evening FOR MOZ005>008-
015>017-023>025-032-033-040.
WINTER WEATHER ADVISORY until 3 PM CST this afternoon FOR
MOZ001>003-011.
KS...WINTER STORM WARNING until 3 PM CST this afternoon FOR KSZ025-
057-060-102>105.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1130 AM MST Tue Feb 26 2013
.DISCUSSION...
Update forthcoming. Have adjusted qpf and snow amounts this morning.
Otherwise, current forecast looks good. Moist unstable northwest
flow aloft over the area contributing to areas of light snow. Radar
showing heaviest band just east of Great Falls. RUC indicates snow
will gradually end by late afternoon. Temperatures look reasonable.
Emanuel
&&
.AVIATION...
Updated 1830Z.
Scattered light snow showers will affect Central Montana through
21z...with brief periods of IFR conditions in heavier snow showers.
Expect partial clearing tonight...with most areas under VFR
conditions. Some mountains will be obscured at times through the
afternoon...especially over Central MT from Great Falls to
Lewistown. Brusda
&&
.PREV DISCUSSION...ISSUED 411 AM MST Tue Feb 26 2013
Today through Thursday...An upper level trough axis extends from
Alberta south through the U.S. Rockies this morning. Main energy
within the trough is diving southeast through UT while a weaker
embedded vorticity center looks to be centered along the MT/AB
border per satellite imagery this morning. A moist NW flow aloft
will continue over the region today as the upper trough axis
shifts east across MT, keeping the threat for occasional showers
going over the mtns through most of today. The weak upper level
feature along the Canadian border will also track east today with
an associated shift to NW winds at the surface pushing southeast
through North Central MT this morning. Expect a period of light
snow showers or flurries across portions of North Central MT as
this feature moves through this morning and early this afternoon.
Little or no snow accumulation is anticipated at lower elevations
with around an inch of new snow accumulation possible in the
mountains today. A transient upper level ridge will drift east
across the region tonight through Wednesday morning bringing an
end to shower activity this evening along with clearing skies.
Another shortwave in progressive westerly flow aloft is forecast
to move east into the Northern Rockies late Wednesday, then dive
southeast across MT Wednesday night and Thursday. This will bring
increasing clouds to the forecast area again Wednesday afternoon
with precipitation developing over the mountains again Wednesday
night and continuing through Thursday as additional shortwave and
upper level Jet energy streams across the Northern Rockies. Most
of the precipitation during this period will be over the
mountains with west to southwest surface winds keeping the
Plains/Valleys dry. Temperatures will be slightly below seasonal
averages today with gradual warming Wednesday and Thursday.
Thursday night through Tuesday...Consistency amongst the models
is good into the first part of the weekend. Also for a particular
model..run-to-run consistency is good. So expect northwest flow
aloft Thursday night through Friday night with an upper ridge moving
over the forecast area on Saturday. Will continue with the idea of
scattered snow showers over the mountains at first then diminishing
as the upper ridge approaches. Model consistency for a weather
system for Sunday through Monday has increased with latest model
runs. The associated cold front is expected to move through the
forecast area Sunday while the upper trough moves in Sunday night.
This system looks fairly wet so have increased the chances of snow
but did not go too high with the chances as there still are
differences with regard to model forecast precipitation patterns. In
line with the increased threat for precipitation have also lowered
high temperatures for Monday. By Tuesday the next upper ridge is
forecast to move into western if not central Montana and in
comparison to Monday have lowered the chances of snow and moderated
temperatures slightly. Blank
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 38 20 42 25 / 50 0 10 10
CTB 37 19 43 23 / 40 0 0 10
HLN 38 18 39 24 / 20 10 10 20
BZN 32 11 34 16 / 30 10 10 20
WEY 28 3 27 9 / 50 20 20 30
DLN 32 11 35 16 / 10 0 10 20
HVR 34 16 38 22 / 40 10 0 10
LWT 31 12 38 18 / 30 20 10 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
10 AM MST Tue Feb 26 2013
.DISCUSSION...
Update forthcoming. Have adjusted qpf and snow amounts this morning.
Otherwise, current forecast looks good. Moist unstable northwest
flow aloft over the area contributing to areas of light snow. Radar
showing heaviest band just east of Great Falls. RUC indicates snow
will gradually end by late afternoon. Temperatures look reasonable.
Emanuel
&&
.AVIATION...
Updated 1150Z.
A weather disturbance aloft will be moving through the area today.
It will bring a few snow showers to the lower elevations with more
numerous snow showers over the mountains. Expect some obscurement of
the mountains while lower elevations could see MVFR or possibly even
IFR conditions in the snow showers. With the snow showers do not
expect MVFR/IFR visibilities to last more than an hour. Do not think
there is much threat of MVFR conditions at KHLN and KBZN so did not
include their mention in those two tafs. The main message for late
this afternoon and evening is improving conditions and should see
mostly clear skies by midnight. Although not mentioned in the tafs
there is remote threat of freezing fog at KHVR and KHLN late tonight.
Blank
&&
.PREV DISCUSSION...ISSUED 411 AM MST Tue Feb 26 2013
Today through Thursday...An upper level trough axis extends from
Alberta south through the U.S. Rockies this morning. Main energy
within the trough is diving southeast through UT while a weaker
embedded vorticity center looks to be centered along the MT/AB
border per satellite imagery this morning. A moist NW flow aloft
will continue over the region today as the upper trough axis
shifts east across MT, keeping the threat for occasional showers
going over the mtns through most of today. The weak upper level
feature along the Canadian border will also track east today with
an associated shift to NW winds at the surface pushing southeast
through North Central MT this morning. Expect a period of light
snow showers or flurries across portions of North Central MT as
this feature moves through this morning and early this afternoon.
Little or no snow accumulation is anticipated at lower elevations
with around an inch of new snow accumulation possible in the
mountains today. A transient upper level ridge will drift east
across the region tonight through Wednesday morning bringing an
end to shower activity this evening along with clearing skies.
Another shortwave in progressive westerly flow aloft is forecast
to move east into the Northern Rockies late Wednesday, then dive
southeast across MT Wednesday night and Thursday. This will bring
increasing clouds to the forecast area again Wednesday afternoon
with precipitation developing over the mountains again Wednesday
night and continuing through Thursday as additional shortwave and
upper level Jet energy streams across the Northern Rockies. Most
of the precipitation during this period will be over the
mountains with west to southwest surface winds keeping the
Plains/Valleys dry. Temperatures will be slightly below seasonal
averages today with gradual warming Wednesday and Thursday.
Thursday night through Tuesday...Consistency amongst the models
is good into the first part of the weekend. Also for a particular
model..run-to-run consistency is good. So expect northwest flow
aloft Thursday night through Friday night with an upper ridge moving
over the forecast area on Saturday. Will continue with the idea of
scattered snow showers over the mountains at first then diminishing
as the upper ridge approaches. Model consistency for a weather
system for Sunday through Monday has increased with latest model
runs. The associated cold front is expected to move through the
forecast area Sunday while the upper trough moves in Sunday night.
This system looks fairly wet so have increased the chances of snow
but did not go too high with the chances as there still are
differences with regard to model forecast precipitation patterns. In
line with the increased threat for precipitation have also lowered
high temperatures for Monday. By Tuesday the next upper ridge is
forecast to move into western if not central Montana and in
comparison to Monday have lowered the chances of snow and moderated
temperatures slightly. Blank
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 38 20 42 25 / 50 0 10 10
CTB 37 19 43 23 / 40 0 0 10
HLN 38 18 39 24 / 20 10 10 20
BZN 32 11 34 16 / 30 10 10 20
WEY 28 3 27 9 / 50 20 20 30
DLN 32 11 35 16 / 10 0 10 20
HVR 34 16 38 22 / 40 10 0 10
LWT 31 12 38 18 / 30 20 10 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS BILLINGS MT
304 AM MST TUE FEB 26 2013
.SHORT TERM...VALID FOR TDY AND WED...
THE LARGE-SCALE FLOW WILL REMAIN UNSETTLED THE NEXT TWO DAYS...BUT
WE WILL ACTUALLY HAVE RELATIVELY MILD AND MAINLY QUIET WEATHER.
AS OF 10 UTC...THE DYNAMICS WITH THE WAVE CROSSING THE REGION HAVE
MAINLY GONE TO WASTE ON SATURATING THE MID- AND HIGH-LEVELS IN OUR
RELATIVELY DRY AIR MASS. THIS IS BEING AMPLIFIED BY WESTERLY WINDS
IN THE LOW- AND MID-LEVELS...WHICH IS YIELDING A CLASSIC DOWNSLOPE
SIGNATURE ON RADAR WITH ALL RETURNS EAST AND SOUTH OF BILLINGS. IT
THUS APPEARS THE SNOWFALL WITH THIS WAVE WILL BE EVEN LESS THAN WE
THOUGHT THE LAST FEW DAYS. SNOWFALL RATES WILL PROBABLY BE TOO LOW
TO CAUSE WIDESPREAD PROBLEMS...AND IN SOME CASES ROAD TEMPERATURES
WILL ALREADY BE BELOW 32 F WHEN /OR PERHAPS IF/ SNOWFALL BEGINS IN
PLACES LIKE SHERIDAN...THUS REDUCING TRAVEL IMPACTS. WE THUS CHOSE
TO CANCEL THE PREVIOUSLY-ISSUED WINTER WEATHER ADVISORY EARLY.
TODAY...BASED ON LINGERING FORCING...WE WILL HAVE CHANCE-TYPE POPS
IN PLACE FOR SPOTS LIKE SHERIDAN AND BROADUS...WITH LIKELY POPS IN
THE BIG HORN MOUNTAINS. HOWEVER...THAT MAY STILL BE TOO MUCH. EVEN
MANY RECENT RAP RUNS SUGGEST MINIMAL PRECIPITATION FOR THOSE AREAS
ONCE THEY GET PAST THE FIRST COUPLE FORECAST HOURS /WHEN THE MODEL
IS BEING NEGATIVELY-INFLUENCED BY WEIGHTING TO EARLY-MORNING RADAR
IMAGES THAT ARE OVERESTIMATING SURFACE PRECIPITATION/. WE CHOSE TO
CARRY A SLIGHT CHANCE OF SHOWERS IN MOST PLACES AFTER 18 UTC SINCE
FORECAST SOUNDINGS SHOW ENOUGH INSTABILITY FOR SHALLOW CONVECTION.
THE BOUNDARY LAYER MAY ACTUALLY BE WARM ENOUGH TO YIELD A MIX WITH
RAIN IF SOME CONVECTION FORMS. SPEAKING OF THAT WARMTH...OUR MILD
START AND MIXING BENEATH SOME MID-LEVEL COLD AIR ADVECTION WILL BE
ENOUGH TO PUSH HIGHS INTO THE 40S F AGAIN IN MANY PLACES. THE SAME
ENVIRONMENT WILL ALLOW ACCESS TO 30 KT OF WIND ALOFT TOO.
TONIGHT...LOW POPS ARE LINGERED THROUGH 06 UTC IN MOST AREAS...AND
IN FAR SOUTHEAST MT THROUGH THE NIGHT. THAT IS IN RESPECT TO SMALL
CAPE THAT LINGERS ON FORECAST SOUNDINGS INTO THE EVENING...AND THE
PASSAGE OF A SUBTLE 500-HPA SHORT WAVE TROUGH. NOTE THAT WE LEANED
ON 00 UTC BIAS-CORRECTED GFS GRIDDED MOS FOR LOWS TONIGHT AS THAT
GUIDANCE HAS RECENTLY PERFORMED VERY WELL 24 HOURS OUT.
WED AND WED NIGHT...BRIEF SHORT WAVE RIDGING WILL CROSS THE REGION
AHEAD OF ANOTHER WEAK 500-HPA TROUGH STAGED FOR WED NIGHT. WE HAVE
LOW POPS IN PLACE WED NIGHT FOR THAT FEATURE. CHANGES TO THIS TIME
FRAME INCLUDED 1/ LEVERAGING THE BIAS-CORRECTED MODEL CONSENSUS TO
INCREASE HIGHS ON WED...AND 2/ INCREASING WINDS AROUND BIG TIMBER.
THE LATTER CHANGE IS BASED ON AN INCREASING SURFACE GRADIENT WHICH
LOOKS FAVORABLE FOR WINDS CENTERED ON BIG TIMBER GIVEN A MAGNITUDE
OF AT LEAST 10 HPA FROM IDAHO FALLS TO LEWISTOWN. SCHULTZ
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MODELS IN GOOD AGREEMENT THURSDAY INTO SATURDAY. DISTURBANCE IN
NORTHWESTERLY FLOW WILL HAVE THE POTENTIAL FOR A FEW SNOW SHOWERS
ON THURSDAY...MAINLY IN THE MOUNTAINS. RIDGING DEVELOPS THURSDAY
AFTERNOON INTO SATURDAY...THOUGH PLENTY OF MID AND UPPER LEVEL
MOISTURE WILL CONTINUE TO FLOW OVER THE AREA. THIS MOIST FLOW WILL
BRING SNOW SHOWERS TO AREA MOUNTAINS THURSDAY NIGHT THROUGH FRIDAY
NIGHT...WITH LOWER ELEVATIONS STAYING DRY AND WARMING UP INTO THE
LOWER 50S BY FRIDAY AFTERNOON. WARM CONDITIONS WILL CONTINUE INTO
SATURDAY WITH HIGHS IN THE 45 TO 55 DEGREE RANGE DESPITE
CONSIDERABLE CLOUD COVER.
FORECAST FOR SUNDAY INTO THE MIDDLE OF NEXT WEEK IS MUCH LESS
CERTAIN WITH MODELS CONTINUING TO STRUGGLE WITH PACIFIC ENERGY AND
NORTHWESTERLY FLOW DURING THIS PERIOD. ECMWF HAD BEEN THE MOST
CONSISTENT MODEL THE PAST FEW DAYS BUT HAS CHANGED CONSIDERABLY
WITH THE LATEST RUN. THE GFS WHICH WAS THE DRIER AND WARMER OF THE
MODELS THE PAST FEW DAYS IS NOW THE COLD AND SNOW LEADER. MODELS
ARE ALSO STRUGGLING WITH THE POTENTIAL FOR MID WEEK COLD SURGE AS
THE GFS NOW TAPS THE HUDSON BAY LOW AND DRAGS CHUNK OF VERY COLD
AIR WHILE THE ECMWF WHICH DID THE SAME THE PAST FEW DAYS NOW
BLOCKS THIS COLD AIR FROM ADVECTING WESTWARD. AS A RESULT MADE
FEW CHANGES TO THE LATER EXTENDED AND KEPT BROADBRUSH CLIMO TYPE
POPS WITH TEMPERATURES TRENDING NEAR OR SLIGHTLY BELOW AVERAGE
AFTER SUNDAY. CHAMBERS
&&
.AVIATION...
VFR CONDITIONS WILL BE PREDOMINANT OVER THE AREA TODAY. A WEAK
SYSTEM WILL MOVE OUT OF EASTERN ZONES THIS MORNING WITH ISOLATED
TO SCATTERED SNOW SHOWERS IN ITS WAKE CONTINUING INTO THIS
EVENING. LOCAL MVFR CONDITIONS CAN BE EXPECTED NEAR SNOW SHOWER
ACTIVITY. OCCASIONAL MOUNTAIN AND PASS OBSCURATION CAN BE EXPECTED
TODAY. NORTHWEST WINDS AT 10 TO 20 KTS ARE FORECAST FOR ALL AREAS
TODAY. CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 043 021/042 024/041 030/049 034/054 035/048 031/037
2/W 20/U 21/B 11/E 00/B 13/W 43/J
LVM 035 017/039 021/040 023/046 027/048 029/044 025/033
2/J 11/N 21/B 11/E 11/B 24/W 43/J
HDN 042 019/041 020/039 027/046 033/051 033/048 030/036
3/W 20/U 21/B 11/B 00/B 13/W 33/J
MLS 047 025/044 024/043 027/050 033/053 034/050 031/037
2/J 20/B 11/B 11/B 10/B 02/W 33/J
4BQ 040 021/040 018/039 025/045 032/050 031/047 030/037
4/J 30/B 11/B 11/B 10/B 02/W 33/J
BHK 045 024/037 020/039 024/045 030/047 031/046 028/035
2/J 21/B 11/B 11/B 10/B 02/W 33/J
SHR 037 011/035 012/036 021/042 028/048 029/047 027/034
4/J 30/U 11/B 11/B 00/U 03/J 43/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
255 AM EST TUE FEB 26 2013
.SYNOPSIS...
A POWERFUL STORM SYSTEM WILL MOVE FROM THE SOUTHERN PLAINS INTO THE
OHIO VALLEY TODAY... BRINGING A COLD FRONT FROM SOUTHWEST TO
NORTHEAST THROUGH NORTH CAROLINA LATE TODAY THROUGH TONIGHT. AS DEEP
LOW PRESSURE SLIDES EAST ACROSS THE MIDATLANTIC REGION AND NORTHEAST
STATES WEDNESDAY INTO THURSDAY... GENERALLY DRY WEATHER WITH PERIODS
OF CLOUDS ARE EXPECTED OVER OUR AREA.
&&
.NEAR TERM /THROUGH TUESDAY NIGHT/...
AS OF 955 PM MONDAY...
HIGH AND MID LEVEL CLOUDS HAVE RETURNED TO THE SECTIONS OF THE
WESTERN AND NORTHERN PIEDMONT THAT EARLIER THIS EVENING EXPERIENCED
PARTIAL CLEARING. LOW LEVEL NE WINDS CONTINUE TO FEED COOL DRY AIR
INTO THE REGION. LATEST SFC WET BULB ANALYSIS HAS WET BULB TEMPS
BELOW FREEZING ACROSS THE NORTHERN PIEDMONT AND THE NORTHERN COASTAL
PLAIN. NEAR TERM MODEL GUIDANCE HAS A GOOD HANDLE ON THIS SCENARIO
WITH SFC WET BULBS BELOW FREEZING ACROSS ALL OF THE PIEDMONT AND
MUCH OF THE COASTAL PLAIN BY MIDNIGHT THEN SLOWLY RETREAT NWD WITH
TIME.
MODEL TIMING OF THE MAIN PRECIP SHIELD CONTINUES TO SLOW/LAG PER
LATEST RADAR TRENDS. THE LATEST HRRR VERIFYING WELL WITH THE MAIN
PRECIP AREAS ACROSS THE LOWER MS VALLEY AND THE DEEP SOUTH BUT IS
OVEREMPHASIZING THE SPOTTY PRECIP OUT AHEAD THAT SHOULD BE OCCURRING
ACROSS THE SAVANNAH RIVER VALLEY. STILL APPEARS THAT PRECIP WILL
LIKELY NOT REACH OUR SOUTHERN COUNTIES UNTIL 2-4 AM...THEN EXPAND TO
THE NNE. BASED ON PRECIP TIMING AND CURRENT ANTECEDENT
CONDITIONS...ENOUGH COOLING MAY OCCUR IN THE LOWER LEVELS TO CAUSE
THE RAIN TO EITHER START OUT BRIEFLY OR MIX WITH FREEZING AND/OR
SLEET BEFORE TRANSITIONING TO ALL RAIN. WINTRY PRECIP AMOUNTS DON`T
APPEAR ENOUGH TO CAUSE ANY ACCUMULATION OR WIDESPREAD TRAVEL
PROBLEMS. SPS SHOULD COVER THE SCENARIO...IF IT OCCURS.
LITTLE CHANGE REQUIRED TO HOURLY TEMP/MIN TEMP FORECAST. -WSS
TUESDAY...
A POTENT UPPER LEVEL LOW AND ATTENDANT SFC LOW WILL TRACK NORTHEAST
INTO THE CENTRAL MS RIVER VALLEY BY 12Z TUE...AND INTO THE TN/OH
VALLEY BY 00Z WED. SOUTHWEST FLOW ALOFT IS EXPECTED DOWNSTREAM OVER
THE CAROLINAS.
PRECIPITATION CHANCES:
FORCING FOR PRECIP ON TUE WILL BE COMPRISED OF STRONG LOW-LEVEL WARM
ADVECTION...INCREASINGLY DIFFLUENT FLOW ALOFT DOWNSTREAM OF THE
AFOREMENTIONED UPPER LEVEL LOW PROGRESSING TOWARD THE OH VALLEY...
AND SMALL AMPLITUDE DISTURBANCES IN SW FLOW ALOFT. THE STRONGEST
UPPER LEVEL FORCING ASSOC/W SHORTWAVE ENERGY ROTATING AROUND THE
UPPER LOW SHOULD REMAIN LARGELY WEST/NW OF CENTRAL NC THROUGH THE
DAY TUE. THE MAIN CHANGE WITH THE FORECAST TODAY IS A SLOWER ONSET
TO PRECIP. THE SLOWER ONSET VIA THE 12Z MODEL RUNS AND SIMULATED REF
FORECASTS MAY BE DUE TO THE DRY ANTECEDENT AIRMASS IN PLACE AND MCS
ACTIVITY EXPECTED TO DEVELOP UPSTREAM OVER THE DEEP SOUTH LATE THIS
AFT/EVE INTO TONIGHT...WHICH COULD ALTER THE LOW-LEVEL HEIGHT/WIND
PATTERN OVER THE SOUTHEAST PRIOR TO THE DEVELOPMENT OF A STRONG SE
LLJ DURING THE DAY TUE. ALL MODEL GUIDANCE STILL GENERATES A GOOD
1.00-1.50" OF RAIN ACROSS THE AREA. DESPITE MCS ACTIVITY UPSTREAM
OVER THE DEEP SOUTH TONIGHT...A STRONG SOUTHEASTERLY LOW-LEVEL JET
/ATLANTIC MOISTURE FEED/ IS ANTICIPATED DURING THE DAY TUE...AND
SHOULD ALLOW FOR MODERATE TO OCCASIONALLY HEAVY RAIN ACROSS THE
AREA...ENHANCED BY THE PRESENCE OF MARGINAL MUCAPE ASSOC/W THE H85
WARM NOSE ATOP THE WEDGE...WHICH COULD RESULT IN ISOLD ELEVATED
CONVECTION BETWEEN 12-18 OR 12-21Z.
TEMPERATURES:
VERY CHALLENGING TEMPERATURE FCST. THE LATEST MODEL GUIDANCE STILL
APPEARS TO BE HAVING DIFFICULTY CAPTURING THE WEDGE EXPECTED TO
DEVELOP TUE MORNING. GIVEN DEWPOINTS IN THE LOWER/MID 20S AND
LOWER-THAN-EXPECTED TEMPERATURES THIS AFTERNOON...RANGING FROM THE
UPPER 30S TO LOWER 40S...EXPECT THAT THE STAGE IS SET FOR THE
DEVELOPMENT OF A STRONG CAD WEDGE AT THE ONSET OF PRECIP TUE
MORNING. WILL BASE THE TEMPERATURE FCST MORE-SO ON PATTERN
RECOGNITION IN THIS TYPE OF SETUP...WITH HIGHS ON TUE RANGING FROM
THE UPPER 30S/LOWER 40S IN THE TRIAD TO LOWER/MID 60S IN THE FAR SE
COASTAL PLAIN...IN CLOSER PROXIMITY TO A WAVE OF LOW PRESSURE
EXPECTED TO DEVELOP ALONG THE EASTERN PERIPHERY OF THE WEDGE.
SEVERE THREAT:
THE LATEST DAY 2 OUTLOOK FROM THE STORM PREDICTION CENTER INCLUDES
THE BULK OF CENTRAL NC (ASIDE FROM THE FAR N/NW PIEDMONT) IN A
SLIGHT RISK FOR SEVERE THUNDERSTORMS. HOWEVER...PATTERN RECOGNITION
AND PREVIOUS EXPERIENCE WOULD SUGGEST THAT MODEL GUIDANCE IS NOT
PROPERLY HANDLING THE WEDGE AIRMASS EXPECTED TO DEVELOP AND THAT THE
BAROCLINIC ZONE...ENSUING CYCLOGENESIS...AND BRIEF/NARROW WARM
SECTOR TUE AFTERNOON WILL LARGELY REMAIN EAST OF CENTRAL NC. AS A
RESULT...FEEL THAT THE BEST CHANCE OF SFC-BASED CONVECTION WILL
REMAIN OVER EASTERN (ESP. COASTAL) NC. IT IS AT LEAST POSSIBLE THAT
THE WEDGE FRONT COULD BRIEFLY MOVE FURTHER INLAND ACROSS THE
SOUTHEAST COASTAL PLAIN IN ASSOC/W STRENGTHENING SE LOW-LEVEL FLOW
TUE AFTERNOON...AND A LOW-END POTENTIAL FOR ISOLD SEVERE CONVECTION
OF THE HIGH SHEAR/LOW CAPE VARIETY CANNOT BE RULED OUT...PRIMARILY
IN CUMBERLAND...SAMPSON AND WAYNE COUNTIES. -VINCENT
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 150 AM TUESDAY...
FOR WEDNESDAY/WEDNESDAY NIGHT: THE MID LEVEL VORTEX IS EXPECTED TO
BE OVER NRN OH WEDNESDAY MORNING WITH A SECONDARY LOW NEAR STL ALONG
A TRAILING TROUGH... WHILE SURFACE LOWS WITH THE OCCLUDED FRONTAL
SYSTEM SIT OVER THE NRN OH/IN BORDER AND NEAR PHL. THE LEADING COLD
FRONT WILL BE PUSHING WELL OFF THE COAST WITH DEEP CYCLONIC WSW FLOW
OVER NC... AWAITING THE SECONDARY COLD FRONT PASSAGE AS THE OH/IN
LOW TRACKS EAST TO NY/PA WEDNESDAY NIGHT. THE COLUMN WILL DRY OUT BY
DAYBREAK WEDNESDAY BUT THE WSW LOW LEVEL FLOW WILL NOT INITIALLY
PERMIT A LOT OF DRYING IN THE EVENTUAL MIXED LAYER... SO BENEATH THE
INVERSION ALOFT WE SHOULD SEE SCATTERED-BROKEN FLAT CUMULUS
ESPECIALLY IN THE AFTERNOON. THE NAM/GFS/ECMWF DEPICT A BRIEF
RESURGENCE IN LOW LEVEL MOISTURE TRANSPORT EAST OF HIGHWAY 1
WEDNESDAY LATE AFTERNOON/EVENING... ALONG AND AHEAD OF THE SECONDARY
COLD FRONT ACCOMPANIED BY A SHEARED VORTICITY LOBE ALONG THE PASSING
MID LEVEL TROUGH AXIS. THE MOISTURE RETURN DOES NOT APPEAR TO BE
SUFFICIENT ANY APPRECIABLE PRECIP... PARTICULARLY CONSIDERING THAT
ANY DYNAMIC FORCING FOR ASCENT WILL BE WEAK AND ROOTED IN THE HIGH
LEVELS... LIMITED TO DPVA AND UPPER DIVERGENCE (WITH THE 160 KT
JETLET OVER THE SC COAST)... BUT WILL CONTINUE TO KEEP AN EYE OUT
FOR THIS POTENTIAL ACROSS THE NRN TIER OF CENTRAL NC COUNTIES... AS
THE GFS DOES GENERATE LIGHT QPF OVER THE VA BORDER AND NRN NC AS THE
700 MB TROUGH PASSES THROUGH THE AREA WEDNESDAY NIGHT. FORECAST
SOUNDINGS AND THE DRY ADIABATIC PROFILE IN THE MIXED LAYER SUPPORT
HIGHS OF 56-64... UNDER PARTLY TO MOSTLY CLOUDY SKIES. LOWS
WEDNESDAY NIGHT 33-38 AS CLOUDS... BREEZE... AND DELAY IN LOW LEVEL
COLD AIR ADVECTION LIMIT COOLING. EXPECT A STOUT SW BREEZE WEDNESDAY
WITH PERIODIC GUSTS TO 25 KTS AS 925 MB WINDS OF 20-30 MPH PARTIALLY
MIX DOWN TO THE SURFACE MAINLY IN THE AFTERNOON/EVENING.
FOR THURSDAY/THURSDAY NIGHT... THE MID LEVEL LOW OVER NY/PA HEADS
SLOWLY EAST... EVENTUALLY PASSING OFF THE NORTHEAST COAST LATE
THURSDAY OR THURSDAY NIGHT WITH STRONG MID LEVEL HEIGHT RISES
(50-100 METERS) OVER NC. WE WILL MAINTAIN A DEEP CYCLONIC FLOW OVER
NC WITH ENHANCED MOISTURE PERSISTING IN THE 850-700 MB LAYER... SO
EXPECT CONTINUED PARTLY TO MOSTLY CLOUDY SKIES THURSDAY... GREATEST
COVERAGE NORTH... CLEARING THURSDAY NIGHT AS THE 700 MB TROUGH HEADS
TO OUR EAST FOLLOWED BY DOWNSLOPE DRYING. LOW LEVEL THICKNESSES DROP
BACK TO 10-15 METERS BELOW NORMAL... INDICATIVE OF HIGHS REACHING
49-56... WITH NW WINDS OF 10-20 KTS GUSTING TO 25 KTS AS WE MIX UP
TO 800 MB WITH A TIGHT MSLP GRADIENT. LOWS 28-33 WITH DIMINISHING
WINDS. -GIH
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 250 AM TUESDAY...
CHILLY AND UNSETTLED THIS WEEKEND... AND THE RISK OF LIGHT RAIN OR
SNOW SHOWERS PARTICULARLY ON SATURDAY IS INCREASING.
AS THE VORTEX SHIFTS FURTHER OFF THE NORTHEAST COAST ON FRIDAY...
HIGH PRESSURE CLOSES OFF OVER NORTHERN LOWER MI... WHILE SHORTWAVE
ENERGY UNDERCUTS THE ANTICYCLONE... DROPPING FROM THE UPPER MIDWEST
INTO THE CENTRAL MISS VALLEY WHERE IT BRIEFLY CLOSES OFF. WITH LIGHT
MAINLY NORTHERLY SURFACE FLOW AND FLAT DECELERATING MID LEVEL
FLOW... FRIDAY SHOULD BE RELATIVELY QUIET BUT COOL AS LOW LEVEL
THICKNESSES DROP ANOTHER 10 METERS FROM THURSDAY. HIGHS 47-53 UNDER
PARTLY CLOUDY SKIES. LOWS 28-34.
THE LOW NEAR MEMPHIS LATE FRIDAY SHIFTS EASTWARD ACROSS SRN TN AND
INTO NC/VA BY LATE SATURDAY... A SCENARIO AGREED UPON FAIRLY WELL BY
THE OP GFS AND ECMWF AND GENERALLY SUPPORTED BY THE EACH MODEL`S
ENSEMBLE MEAN. THE GFS HAS BEEN TRENDING TOWARD GREATER AMPLITUDE...
AND BY ALL ACCOUNTS THIS IS EXPECTED TO BE AN ANOMALOUSLY DEEP
TROUGH OVER THE SOUTHEAST STATES... 3-4 STANDARD DEVIATIONS BELOW
NORMAL AND UNUSUAL 100+ METER HEIGHT FALS OVER FL AND THE EASTERN
GULF. WEAK LOW PRESSURE IS EXPECTED TO FORM OVER THE DEVELOPING
BAROCLINIC ZONE OFF THE NC COAST SATURDAY... AND THE RESULANT
NORTHEAST LOW LEVEL FLOW SHOULD HELP DRAW IN LOW LEVEL ATLANTIC
MOISTURE TO COINCIDE WITH DYNAMIC COOLING AND SATURATION ALOFT AS
THE CORE OF THE LOW APPROACHES. GFS BUFR SOUNDINGS BECOME QUITE
MOIST (NEARLY SATURATED) FROM THE SURFACE TO 500 MB LATE SATURDAY
AND SATURDAY NIGHT... WITH A PROFILE THAT IS ENTIRELY BELOW FREEZING
(TO AS COLD AS -25C TO -30C) EXCEPT PERHAPS RIGHT NEAR THE GROUND.
FORECAST MID LEVEL LAPSE RATES ARE IMPRESSIVE... 6.5-7.3 C/KM FROM
850-500 MB FROM SATURDAY AFTERNOON THROUGH SUNDAY ON THE GFS
(ALTHOUGH THEY ARE A BIT LOWER AT 6.0 C/KM ON THE ECMWF)... AND
BASED ON THE MODEL TRENDS TOWARD A STRONGER SYSTEM AND WETTER AND
MORE UNSTABLE PROFILE... WILL INTRODUCE A SMALL CHANCE OF LIGHT RAIN
OR LIGHT SNOW LATE SATURDAY THROUGH MIDDAY SUNDAY. THE SPECIFIC TYPE
WILL DEPEND ON THE WET BULB PROFILE IN THE LOWEST 1-2 THOUSAND FEET
AGL... A FACTOR THAT IS IMPOSSIBLE TO SPECIFY THIS FAR OUT IN TIME.
WILL LOWER FORECAST HIGHS A BIT SATURDAY/SUNDAY... IN THE 40S... AS
WE SHOULD SEE EXPANSIVE CLOUD COVER FOR THE MAJORITY OF BOTH DAYS.
LOWS 26-32.
THE LOW IS EXPECTED TO LIFT TO OUR NORTHEAST SUNDAY NIGHT... AND
WITH DEEP DRYING/SUBSIDENCE AND RISING HEIGHTS IN ITS WAKE... EXPECT
FAIR AND CHILLY WEATHER MONDAY WITH THICKNESSES 30-40 METERS BELOW
NORMAL. HIGHS ONCE AGAIN IN THE MID-UPPER 40S. -GIH
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1245 AM TUESDAY...
OBSERVATIONS MISSING FROM KRWI. A NOTAM HAS BEEN ISSUED AND THE KRWI
TAF MAY NOT BE AMENDED UNTIL OBSERVATIONS RETURN.
VFR CONDITIONS CONTINUE AT NEARLY ALL LOCATIONS ACROSS CENTRAL NC AS
LOW CLOUDS HOLD TO OUR SOUTH ACROSS GA AND SC. NEAR TERM MODELS
SHOW THESE MVFR CEILINGS SPREADING TOWARD KFAY AND KGSO/KINT BETWEEN
08-10Z AS A LARGE AREA OF RAIN SPREADS INTO THE REGION AHEAD OF A
LOW PRESSURE SYSTEM MOVING OUT OF THE DEEP SOUTH. CONDITIONS WILL
DETERIORATE QUICKLY AFTER 12Z...WITH CEILINGS AND VSBYS DROPPING
INTO THE IFR/LIFR RANGE AND PERIODS OF MODERATE TO HEAVY RAIN. LOW
LEVEL WIND SHEAR WILL ALSO BE A CONCERN BETWEEN 15Z AND 21Z AS A
STRONG SOUTHERLY LOW LEVEL JET OF OVER 50 KT SURGES ATOP THE
NORTHEASTERLY SURFACE WINDS. ISOLATED THUNDERSTORMS WILL BE
POSSIBLE DURING THE AFTERNOON...MOSTLY FROM KRDU SOUTH AND
EAST...THOUGH THERE IS A BIT MORE UNCERTAINTY REGARDING WHETHER
STORMS WILL BE ABLE TO DEVELOP.
SOME IMPROVEMENT IN CONDITIONS IS EXPECTED AFTER 00Z WEDNESDAY AS A
SOUTHWESTERLY WIND DEVELOPS AND A DRY FRONT SWEEP ACROSS THE AREA.
HOWEVER...THE RESIDUAL POOL OF MOISTURE OVER THE WESTERN PIEDMONT
MAY LEAD TO A GREATER PROBABILITY OF MVFR/IFR CEILINGS AT KGSO/KINT
OVERNIGHT.
OUTLOOK...
VFR CONDITIONS ARE EXPECTED TO RETURN TO THE AREA EARLY WEDNESDAY
MORNING BEHIND THE DEPARTING FRONT AND THEN PERSIST THROUGH THE
REMAINDER OF THE WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...WSS/VINCENT
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...KRR/SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1245 AM EST TUE FEB 26 2013
.SYNOPSIS...
A POTENT STORM SYSTEM WILL MOVE FROM THE LOWER MIDWEST INTO THE OHIO
VALLEY LATE TONIGHT AND TUESDAY. AN ASSOCIATED COLD FRONT WILL MOVE
EAST ACROSS CENTRAL NORTH CAROLINA TUESDAY NIGHT AND WEDNESDAY
MORNING.
&&
.NEAR TERM /TONIGHT/...
AS OF 955 PM MONDAY...
HIGH AND MID LEVEL CLOUDS HAVE RETURNED TO THE SECTIONS OF THE
WESTERN AND NORTHERN PIEDMONT THAT EARLIER THIS EVENING EXPERIENCED
PARTIAL CLEARING. LOW LEVEL NE WINDS CONTINUE TO FEED COOL DRY AIR
INTO THE REGION. LATEST SFC WET BULB ANALYSIS HAS WET BULB TEMPS
BELOW FREEZING ACROSS THE NORTHERN PIEDMONT AND THE NORTHERN COASTAL
PLAIN. NEAR TERM MODEL GUIDANCE HAS A GOOD HANDLE ON THIS SCENARIO
WITH SFC WET BULBS BELOW FREEZING ACROSS ALL OF THE PIEDMONT AND
MUCH OF THE COASTAL PLAIN BY MIDNIGHT THEN SLOWLY RETREAT NWD WITH
TIME.
MODEL TIMING OF THE MAIN PRECIP SHIELD CONTINUES TO SLOW/LAG PER
LATEST RADAR TRENDS. THE LATEST HRRR VERIFYING WELL WITH THE MAIN
PRECIP AREAS ACROSS THE LOWER MS VALLEY AND THE DEEP SOUTH BUT IS
OVEREMPHASIZING THE SPOTTY PRECIP OUT AHEAD THAT SHOULD BE OCCURRING
ACROSS THE SAVANNAH RIVER VALLEY. STILL APPEARS THAT PRECIP WILL
LIKELY NOT REACH OUR SOUTHERN COUNTIES UNTIL 2-4 AM...THEN EXPAND TO
THE NNE. BASED ON PRECIP TIMING AND CURRENT ANTECEDENT
CONDITIONS...ENOUGH COOLING MAY OCCUR IN THE LOWER LEVELS TO CAUSE
THE RAIN TO EITHER START OUT BRIEFLY OR MIX WITH FREEZING AND/OR
SLEET BEFORE TRANSITIONING TO ALL RAIN. WINTRY PRECIP AMOUNTS DON`T
APPEAR ENOUGH TO CAUSE ANY ACCUMULATION OR WIDESPREAD TRAVEL
PROBLEMS. SPS SHOULD COVER THE SCENARIO...IF IT OCCURS.
LITTLE CHANGE REQUIRED TO HOURLY TEMP/MIN TEMP FORECAST.
&&
.SHORT TERM /TUESDAY/...
AS OF 315 PM MONDAY...
OVERVIEW:
A POTENT UPPER LEVEL LOW AND ATTENDANT SFC LOW WILL TRACK NORTHEAST
INTO THE CENTRAL MS RIVER VALLEY BY 12Z TUE...AND INTO THE TN/OH
VALLEY BY 00Z WED. SOUTHWEST FLOW ALOFT IS EXPECTED DOWNSTREAM OVER
THE CAROLINAS.
PRECIPITATION CHANCES:
FORCING FOR PRECIP ON TUE WILL BE COMPRISED OF STRONG LOW-LEVEL WARM
ADVECTION...INCREASINGLY DIFFLUENT FLOW ALOFT DOWNSTREAM OF THE
AFOREMENTIONED UPPER LEVEL LOW PROGRESSING TOWARD THE OH VALLEY...
AND SMALL AMPLITUDE DISTURBANCES IN SW FLOW ALOFT. THE STRONGEST
UPPER LEVEL FORCING ASSOC/W SHORTWAVE ENERGY ROTATING AROUND THE
UPPER LOW SHOULD REMAIN LARGELY WEST/NW OF CENTRAL NC THROUGH THE
DAY TUE. THE MAIN CHANGE WITH THE FORECAST TODAY IS A SLOWER ONSET
TO PRECIP. THE SLOWER ONSET VIA THE 12Z MODEL RUNS AND SIMULATED REF
FORECASTS MAY BE DUE TO THE DRY ANTECEDENT AIRMASS IN PLACE AND MCS
ACTIVITY EXPECTED TO DEVELOP UPSTREAM OVER THE DEEP SOUTH LATE THIS
AFT/EVE INTO TONIGHT...WHICH COULD ALTER THE LOW-LEVEL HEIGHT/WIND
PATTERN OVER THE SOUTHEAST PRIOR TO THE DEVELOPMENT OF A STRONG SE
LLJ DURING THE DAY TUE. ALL MODEL GUIDANCE STILL GENERATES A GOOD
1.00-1.50" OF RAIN ACROSS THE AREA. DESPITE MCS ACTIVITY UPSTREAM
OVER THE DEEP SOUTH TONIGHT...A STRONG SOUTHEASTERLY LOW-LEVEL JET
/ATLANTIC MOISTURE FEED/ IS ANTICIPATED DURING THE DAY TUE...AND
SHOULD ALLOW FOR MODERATE TO OCCASIONALLY HEAVY RAIN ACROSS THE
AREA...ENHANCED BY THE PRESENCE OF MARGINAL MUCAPE ASSOC/W THE H85
WARM NOSE ATOP THE WEDGE...WHICH COULD RESULT IN ISOLD ELEVATED
CONVECTION BETWEEN 12-18 OR 12-21Z.
TEMPERATURES:
VERY CHALLENGING TEMPERATURE FCST. THE LATEST MODEL GUIDANCE STILL
APPEARS TO BE HAVING DIFFICULTY CAPTURING THE WEDGE EXPECTED TO
DEVELOP TUE MORNING. GIVEN DEWPOINTS IN THE LOWER/MID 20S AND
LOWER-THAN-EXPECTED TEMPERATURES THIS AFTERNOON...RANGING FROM THE
UPPER 30S TO LOWER 40S...EXPECT THAT THE STAGE IS SET FOR THE
DEVELOPMENT OF A STRONG CAD WEDGE AT THE ONSET OF PRECIP TUE
MORNING. WILL BASE THE TEMPERATURE FCST MORE-SO ON PATTERN
RECOGNITION IN THIS TYPE OF SETUP...WITH HIGHS ON TUE RANGING FROM
THE UPPER 30S/LOWER 40S IN THE TRIAD TO LOWER/MID 60S IN THE FAR SE
COASTAL PLAIN...IN CLOSER PROXIMITY TO A WAVE OF LOW PRESSURE
EXPECTED TO DEVELOP ALONG THE EASTERN PERIPHERY OF THE WEDGE.
SEVERE THREAT:
THE LATEST DAY 2 OUTLOOK FROM THE STORM PREDICTION CENTER INCLUDES
THE BULK OF CENTRAL NC (ASIDE FROM THE FAR N/NW PIEDMONT) IN A
SLIGHT RISK FOR SEVERE THUNDERSTORMS. HOWEVER...PATTERN RECOGNITION
AND PREVIOUS EXPERIENCE WOULD SUGGEST THAT MODEL GUIDANCE IS NOT
PROPERLY HANDLING THE WEDGE AIRMASS EXPECTED TO DEVELOP AND THAT THE
BAROCLINIC ZONE...ENSUING CYCLOGENESIS...AND BRIEF/NARROW WARM
SECTOR TUE AFTERNOON WILL LARGELY REMAIN EAST OF CENTRAL NC. AS A
RESULT...FEEL THAT THE BEST CHANCE OF SFC-BASED CONVECTION WILL
REMAIN OVER EASTERN (ESP. COASTAL) NC. IT IS AT LEAST POSSIBLE THAT
THE WEDGE FRONT COULD BRIEFLY MOVE FURTHER INLAND ACROSS THE
SOUTHEAST COASTAL PLAIN IN ASSOC/W STRENGTHENING SE LOW-LEVEL FLOW
TUE AFTERNOON...AND A LOW-END POTENTIAL FOR ISOLD SEVERE CONVECTION
OF THE HIGH SHEAR/LOW CAPE VARIETY CANNOT BE RULED OUT...PRIMARILY
IN CUMBERLAND...SAMPSON AND WAYNE COUNTIES. -VINCENT
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
AS OF 1150 AM MONDAY...
TUESDAY NIGHT...
AS THE STORM SYSTEM LIFTS NORTH INTO VA AND BEYOND... THE TRAILING
COLD FRONT IS FORECAST TO BE DELAYED UNTIL OVERNIGHT THROUGH 12Z
WED IN THE EAST. THE CAD BOUNDARY MAY ACTUALLY BE PULLED BACK
EASTWARD THROUGH THE COASTAL PLAIN AFTER THE LOW PRESSURE PASSES.
RESIDUAL CAD WILL PLAY A ROLE WITH LOW CEILINGS AND VISIBILITIES
WITH FOG AND EVEN SOME LIGHT DRIZZLE OVER THE PIEDMONT TRIAD REGION.
ANY ADDITIONAL QPF WOULD BE 0.01 OR TRACE AMOUNTS. SOME OF THE
WEATHER ASSOCIATED WITH THE RESIDUAL CAD MAY SPREAD BACK EASTWARD
OVER THE COASTAL PLAIN DURING THE OVERNIGHT OUT AHEAD OF THE MAIN
COLD FRONT THAT WILL ARRIVE LATER. THIS FRONT SHOULD PUSH EAST
THROUGH THE REGION BETWEEN 09Z-13Z OR SO... WITH GOOD MIXING OF DRY
AIR ALOFT DOWN TO THE SURFACE FINALLY BRINGING RAPID CLEARING.
EXPECT THIS RAPID CLEARING TO BEGIN IN THE LEE OF THE BLUE RIDGE
THEN SPREAD OUT OVER THE PIEDMONT AND EVENTUALLY THE COASTAL PLAIN
AS THE FRONT PASSES THROUGH. LOWS SHOULD BE HELD UP IN THE EAST AS
THE FRONT WILL BE DELAYED. THE TEMPS MAY DROP JUST BEFORE SUNRISE IN
THE WEST AS THE DRY AIR ARRIVES. LOWS GENERALLY 35-40 NW RANGING TO
NEAR 50 EAST.
WEDNESDAY-SUNDAY...
THE EUROPEAN OPERATIONAL MODEL ALONG WITH THE EC ENSEMBLE MEAN WERE
FAVORED IN THE MEDIUM RANGE PERIOD FROM WED-SUN. A PROGRESSIVELY
COLDER PATTERN IS EXPECTED OVER THE EASTERN UNITED STATES... WITH
THE COLDEST AIR EXPECTED TO ARRIVE TOWARD THE WEEKEND. THERE IS
STILL A LOW CHANCE OF A COASTAL STORM DEPENDING ON THE EXACT
POSITION/STRENGTH OF THE MID/UPPER LEVEL TROUGH THAT DEVELOPS OVER
THE EASTERN UNITED STATES. THE ARCTIC OSCILLATION AND THE NORTH
ATLANTIC OSCILLATION ARE FOREST TO BECOME STRONGLY NEGATIVE DAYS
6-10... WITH CORRESPONDING POSITIVE HEIGHT ANOMALIES SPREADING FROM
GREENLAND WESTWARD INTO FAR EASTERN CANADA IN THE HIGHER
LATITUDES... SUPPORTING COASTAL DEVELOPMENT OFF THE EAST COAST SAT
OR SUNDAY. JUST HOW FAR WEST THIS SYSTEM CAN DEVELOP WILL MEAN
EITHER DRY AND COLDER OR POSSIBLY WHITE AND COLDER OVER THE WEEKEND.
REGARDLESS... THE EASTERN TROUGH AND FORECAST HEIGHT ANOMALIES
SUPPORTS TEMPERATURES A GOOD 10-15 DEGREES BELOW NORMAL SAT-MON.
SENSIBLE WEATHER...
MILD AND PARTLY SUNNY WEDNESDAY...HIGHS 58-65. WESTERLY WINDS 10-20
MPH. PARTLY CLOUDY/PARTLY SUNNY THURSDAY AND FRIDAY. COLDER. LOWS IN
THE 20S TO AROUND 30. HIGHS 50-55 THURS...AND 45-50 FRI.
SAT-SUN...IMPORTANT PERIOD AS THE MID/UPPER TROUGH WILL DIG OVER THE
SOUTHERN APPALACHIANS...SOME COASTAL LOW POTENTIAL. WE WILL KEEP
FORECAST DRY FOR NOW...BUT THIS PATTERN WILL HAVE TO BE WATCHED.
COLD WITH LOWS IN THE 20S. HIGHS IN THE 40S (NEAR 50 SANDHILLS).
MONDAY...COLD AND DRY. LOWS IN THE 20S. HIGHS IN THE 40S.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1245 AM TUESDAY...
OBSERVATIONS MISSING FROM KRWI. A NOTAM HAS BEEN ISSUED AND THE KRWI
TAF MAY NOT BE AMENDED UNTIL OBSERVATIONS RETURN.
VFR CONDITIONS CONTINUE AT NEARLY ALL LOCATIONS ACROSS CENTRAL NC AS
LOW CLOUDS HOLD TO OUR SOUTH ACROSS GA AND SC. NEAR TERM MODELS
SHOW THESE MVFR CEILINGS SPREADING TOWARD KFAY AND KGSO/KINT BETWEEN
08-10Z AS A LARGE AREA OF RAIN SPREADS INTO THE REGION AHEAD OF A
LOW PRESSURE SYSTEM MOVING OUT OF THE DEEP SOUTH. CONDITIONS WILL
DETERIORATE QUICKLY AFTER 12Z...WITH CEILINGS AND VSBYS DROPPING
INTO THE IFR/LIFR RANGE AND PERIODS OF MODERATE TO HEAVY RAIN. LOW
LEVEL WIND SHEAR WILL ALSO BE A CONCERN BETWEEN 15Z AND 21Z AS A
STRONG SOUTHERLY LOW LEVEL JET OF OVER 50 KT SURGES ATOP THE
NORTHEASTERLY SURFACE WINDS. ISOLATED THUNDERSTORMS WILL BE
POSSIBLE DURING THE AFTERNOON...MOSTLY FROM KRDU SOUTH AND
EAST...THOUGH THERE IS A BIT MORE UNCERTAINTY REGARDING WHETHER
STORMS WILL BE ABLE TO DEVELOP.
SOME IMPROVEMENT IN CONDITIONS IS EXPECTED AFTER 00Z WEDNESDAY AS A
SOUTHWESTERLY WIND DEVELOPS AND A DRY FRONT SWEEP ACROSS THE AREA.
HOWEVER...THE RESIDUAL POOL OF MOISTURE OVER THE WESTERN PIEDMONT
MAY LEAD TO A GREATER PROBABILITY OF MVFR/IFR CEILINGS AT KGSO/KINT
OVERNIGHT.
OUTLOOK...
VFR CONDITIONS ARE EXPECTED TO RETURN TO THE AREA EARLY WEDNESDAY
MORNING BEHIND THE DEPARTING FRONT AND THEN PERSIST THROUGH THE
REMAINDER OF THE WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...WSS
SHORT TERM...VINCENT
LONG TERM...BADGETT
AVIATION...KRR/SMITH
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1008 AM CST TUE FEB 26 2013
.DISCUSSION...
MAIN QUESTION TODAY IS THE FOG/STRATUS AND HOW IT MAY AFFECT
HIGHS. A THIN FINGER OF THIS LAYER HAS PUSHED ALL THE WAY UP
TOWARD KHCO. SOME METARS ARE STILL REPORTING A QUARTER MILE VSBY
WHILE OTHER WEB CAMS NEARBY SHOW DECENT VSBYS. SINCE VSBYS ARE NO
LONGER A CONSISTENT QUARTER MILE WENT AHEAD AND LET THE DENSE FOG
ADVISORY EXPIRE. SHOULD SEE LOTS OF SUN TODAY IN THE NORTHEAST AND
NORTHWEST WHERE TEMPS SHOULD RISE ABOVE 32F AGAIN. TWEAKED HIGHS
UP A BIT AROUND THE LAKE OF THE WOODS AND BEMIDJI AREAS AND
LOWERED THEM A LITTLE IN THE IMMEDIATE RED RIVER VALLEY.
&&
.AVIATION...
SEEING HIGHLY VARIABLE VSBYS JUST LIKE YESTERDAY. TODAY KGFK AND
KFAR WILL BE THE SITES THAT NEED TO BE WATCHED CLOSER THIS MORNING
WHILE THE OTHER SITES REMAIN VFR. FOR KFAR/KGFK WILL GO WITH
CONTINUED IMPROVEMENT THRU THE REST OF THE MORNING.
&&
.PREV DISCUSSION... /ISSUED 340 AM CST TUE FEB 26 2013/
SHORT TERM...
THE MAIN CHALLENGE WILL BE FOG AND LOW CLOUDS THROUGH THIS
MORNING...THEN VERY LIGHT SNOW/FLURRY CHANCES WED/WED NIGHT INTO
THU PERHAPS. ALL MODELS ARE DOING POORLY WITH CURRENT LOW CLOUD/FOG
ALONG AND EAST OF THE VALLEY. THE HRRR IS DOING THE BEST AND WILL
FOLLOW THAT FOR THE NEAR TERM. THEREAFTER...MOST MODELS ARE
SIMILAR WITH NO REAL PREFERENCE.
FOR TODAY...THE BIG QUESTION WILL BE HOW LONG DOES THE DENSE FOG
PERSISTS AND ASSOCIATED LOW CLOUDS ALONG AND EAST OF THE RED RIVER
VALLEY. WE WILL CONTINUE TO MONITOR THE POSSIBLE NORTHWARD
EXPANSION OF THE CURRENT DENSE FOG ADVISORY...WITH CLOUDS HOLDING
DOWN TEMPS WHERE THEY PERSIST TODAY. A WEAK SFC HIGH BUILDS IN
WITH RIDGING ALOFT...LENDING MORE CREDENCE TO CLOUDS/FOG
PERSISTING TODAY WHERE THEY ARE AT SUNRISE.
FOR TONIGHT...WEAK CAA BEGINS IN THE NW AND THERE COULD BE FOG/LOW
CLOUDS IN THE SOUTH AND EAST. FOR NOW WON/T MENTION ANY FOG...BUT
MONITOR WITH LATER FORECASTS. TEMPS WILL BE HIGHLY DEPENDENT ON
HOW MUCH CLEARING DEVELOPS.
ON WED/WED NIGHT...THERE WILL BE LOW LEVEL SATURATION UP TO AROUND
800MB IN THE NORTH ADVECTING SOUTH. THERE SHOULD BE AN AREA OF
LIGHT SNOW/FLURRIES MAINLY IN THE NORTH...OR EVEN SOME FREEZING
DRIZZLE WITH MOST OF THE SATURATION AT TEMPS ABOVE -10C. FOR NOW
WON/T MENTION FREEZING DRIZZLE...BUT POTENTIAL IS THERE. TEMPS
WILL BE A BIT COLDER WED WITH LOW LEVEL CAA AND NORTHERLY WINDS
INCREASING A BIT.
FOR THU/THU NIGHT...COOL AIR ADVECTION CONTINUES AND THERE COULD
BE SOME FLURRIES/LOW CLOUDS ON THU WITH A WEAK UPPER TROUGH. FOR NOW
HAVE KEPT IT DRY WITH TEMPS SLOWLY COOLING FROM NORTH TO SOUTH AND
THE COLUMN SLOWLY DRYING OUT.
LONG TERM (FRI-MONDAY NIGHT)...
MODELS IN FAIR AGREEMENT WITH THE EXTENDED UPPER AIR PATTERN AS
LARGE SCALE POSITIVE PNA DEVELOPS ACROSS THE CONUS FOR THE WEEKEND.
THE RESULT ACROSS THE NORTHERN PLAINS REMAINS A DRY FORECAST FRI TO
SUNDAY WITH NW 500MB FLOW AND INCREASING 1000 TO 500MB THICKNESSES
AS RIDGING WORKS INTO THE REGION. A POTENT WAVE IS EXPECTED TO
DE-AMPLIFY THE RIDGING AND ENTER INTO THE AREA SUNDAY NIGHT INTO
MONDAY...HENCE THE CHC POPS. MODELS TEND TO BREAK DOWN THE POSITIVE
PNA TOO QUICKLY AND HAVE SLOWED THE ARRIVAL OF THE SYSTEM FOR A
COUPLE RUNS ALREADY. WOULDN/T BE SURPRISED IF THE TREND CONTINUES.
NEAR NORMAL TEMPS EXPECTED THROUGH THE PERIOD.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
GODON
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
340 AM CST TUE FEB 26 2013
.SHORT TERM...
THE MAIN CHALLENGE WILL BE FOG AND LOW CLOUDS THROUGH THIS
MORNING...THEN VERY LIGHT SNOW/FLURRY CHANCES WED/WED NIGHT INTO
THU PERHAPS. ALL MODELS ARE DOING POORLY WITH CURRENT LOW CLOUD/FOG
ALONG AND EAST OF THE VALLEY. THE HRRR IS DOING THE BEST AND WILL
FOLLOW THAT FOR THE NEAR TERM. THEREAFTER...MOST MODELS ARE
SIMILAR WITH NO REAL PREFERENCE.
FOR TODAY...THE BIG QUESTION WILL BE HOW LONG DOES THE DENSE FOG
PERSISTS AND ASSOCIATED LOW CLOUDS ALONG AND EAST OF THE RED RIVER
VALLEY. WE WILL CONTINUE TO MONITOR THE POSSIBLE NORTHWARD
EXPANSION OF THE CURRENT DENSE FOG ADVISORY...WITH CLOUDS HOLDING
DOWN TEMPS WHERE THEY PERSIST TODAY. A WEAK SFC HIGH BUILDS IN
WITH RIDGING ALOFT...LENDING MORE CREDENCE TO CLOUDS/FOG
PERSISTING TODAY WHERE THEY ARE AT SUNRISE.
FOR TONIGHT...WEAK CAA BEGINS IN THE NW AND THERE COULD BE FOG/LOW
CLOUDS IN THE SOUTH AND EAST. FOR NOW WON/T MENTION ANY FOG...BUT
MONITOR WITH LATER FORECASTS. TEMPS WILL BE HIGHLY DEPENDENT ON
HOW MUCH CLEARING DEVELOPS.
ON WED/WED NIGHT...THERE WILL BE LOW LEVEL SATURATION UP TO AROUND
800MB IN THE NORTH ADVECTING SOUTH. THERE SHOULD BE AN AREA OF
LIGHT SNOW/FLURRIES MAINLY IN THE NORTH...OR EVEN SOME FREEZING
DRIZZLE WITH MOST OF THE SATURATION AT TEMPS ABOVE -10C. FOR NOW
WON/T MENTION FREEZING DRIZZLE...BUT POTENTIAL IS THERE. TEMPS
WILL BE A BIT COLDER WED WITH LOW LEVEL CAA AND NORTHERLY WINDS
INCREASING A BIT.
FOR THU/THU NIGHT...COOL AIR ADVECTION CONTINUES AND THERE COULD
BE SOME FLURRIES/LOW CLOUDS ON THU WITH A WEAK UPPER TROUGH. FOR NOW
HAVE KEPT IT DRY WITH TEMPS SLOWLY COOLING FROM NORTH TO SOUTH AND
THE COLUMN SLOWLY DRYING OUT.
.LONG TERM (FRI-MONDAY NIGHT)...
MODELS IN FAIR AGREEMENT WITH THE EXTENDED UPPER AIR PATTERN AS
LARGE SCALE POSITIVE PNA DEVELOPS ACROSS THE CONUS FOR THE WEEKEND.
THE RESULT ACROSS THE NORTHERN PLAINS REMAINS A DRY FORECAST FRI TO
SUNDAY WITH NW 500MB FLOW AND INCREASING 1000 TO 500MB THICKNESSES
AS RIDGING WORKS INTO THE REGION. A POTENT WAVE IS EXPECTED TO
DE-AMPLIFY THE RIDGING AND ENTER INTO THE AREA SUNDAY NIGHT INTO
MONDAY...HENCE THE CHC POPS. MODELS TEND TO BREAK DOWN THE POSITIVE
PNA TOO QUICKLY AND HAVE SLOWED THE ARRIVAL OF THE SYSTEM FOR A
COUPLE RUNS ALREADY. WOULDN/T BE SURPRISED IF THE TREND CONTINUES.
NEAR NORMAL TEMPS EXPECTED THROUGH THE PERIOD.
&&
.AVIATION...
LIFR/IFR CONDITIONS IN LOW CLOUDS/FOG CONTINUE ALONG AND EAST OF
THE RED RIVER. EXPECT ALL SITES EXCEPT KDVL TO EXPERIENCE THE LOW
CLOUDS/FOG TO SOME EXTENT. WILL CONTINUE TO MONITOR HOW LONG TO
HANG ONTO THE IFR/LIFR CONDITIONS...AND EXPECT CONDITIONS TO LAST
AT LEAST THROUGH 16Z THIS MORNING...WITH SOME IMPROVEMENT THEREAFTER.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR NDZ039-049-
052-053.
MN...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR MNZ003-024-
027>032-040.
&&
$$
DK/JK
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
119 PM EST TUE FEB 26 2013
.SYNOPSIS...
STRONG LOW PRESSURE WILL MOVE FROM INTO THE GREAT LAKES AREA TODAY
WHILE DRAGGING A COLD FRONT ACROSS OUR AREA. BREEZY CONDITIONS AND
COLDER TEMPERATURES WILL SETTLE IN BEHIND THE FRONT THROUGH
THURSDAY. ON FRIDAY ANOTHER FRONT WILL APPROACH THE AREA FROM THE
WEST AND MOVE THROUGH THE AREA OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
900 AM UPDATE...BACK EDGE OF HEAVIER PCPN WILL BE NEAR DRY SLOT
EVIDENT ON WV IMAGERY. SFC OBS AND RADAR INDICATING SOME SCATTERED
SHOWERS ARE PRESENT BEHIND THE BACK EDGE. ALSO NOTING RAP SOUNDINGS
WHICH STILL SHOW INSTABILITY ABOVE WARM NOSE UNTIL MIDLEVEL COLD
ADVECTION GETS GOING THIS AFTN. THUS MAINTAINED CHC POPS BEHIND THE
SOLID PCPN SHIELD AS WELL AS THUNDER WORDING FROM MRNG PACKAGE.
REVISED TEMP TRENDS TO SLOW WARMING A BIT OVER THE NRN PIEDMONT
WHERE LIGHT ICE ACCUM STILL OCCURRING...PUTTING TEMPS MORE IN LINE
WITH 06Z NAM WHICH VERIFIED BETTER EARLIER THIS MRNG. ALLOWED WINTER
HEADLINES TO EXPIRE OVER THE SW MTNS WHERE TEMPS HAVE MOSTLY WARMED
ABV 0C...BUT EXTENDED BY ONE HOUR THE WINTER STORM WRNG UP NORTH AND
ALSO THE FZRA ADVY FOR THE FOOTHILLS THAT PREVIOUSLY EXPIRED AT 14Z.
PREV DISCUSSION...AS OF 400 AM...THE COMPLEX OCCLUDED LOW AND WEDGE
COMBO SYSTEM IS LIVING UP TO AND SURPASSING EXPECTATIONS A LITTLE
THIS MORNING. THE COOLING ACROSS THE NC MTNS AND THE AMOUNT OF
PRECIP EXPECTED THE NEXT SEVERAL HRS WILL COMBINE TO GIVE A GOOD
AMOUNT OF -FZRA ACROSS THE CENTRAL MTNS AND HIGHER ELEV OF THE SRN
FOOTHILLS...ALONG WITH THE ESCARPMENT AREA NEAR THE SC/NC BORDER.
STILL EVALUATING THE NRN MTNS AND HIGH ELEV NRN FOOTHILLS FOR A
POSSIBLE WARNING UPGRADE...BUT FOR NOW WILL COUNT OF THE PRECIP/ICE
ACCUMS REMAINING THE HIGHEST ACROSS THE AREAS TO THE SOUTH WHERE THE
BEST LIFT AND ISENT OMEGA EXIST. ALSO...WILL ADD A FREEZING RAIN
ADVISORY FOR AREAS EAST OF THE MTNS ACROSS THE NRN/SRN FOOTHILLS AND
THE NC PIEDMONT WEST OF THE I-77 CORRIDOR.
THE MODELS ARE DOING AN ADEQUATE JOB WITH THE DYNAMICS OF THIS
SYSTEM THROUGH THE NEAR TERM AND GIVE GOOD CONFIDENCE WITH THE
WARMING TAKING OVER THE LLVLS BY 14Z OR SO AND CHANGING THE MAJORITY
OF LOCALES TO ALL -RA. HOWEVER...THERE MAY BE SOME LINGERING POCKETS
OF -FZRA ACROSS ISOL MTN VALLEYS THROUGH LATE MORNING. HAVE NOTICED
THE WETBULB FREEZING ZONE EXPANDING IN COVERAGE THIS MORNING INTO
THE UPSTATE AND THREATENING AREAS AROUND CLT AND THE I-77. THIS WILL
BE MONITORED FOR A POSSIBLE FZRA ADVISORY INCLUSION.
THE HIGH WIND WARNING AND ADVISORY ACROSS THE WRN MTNS STILL LOOKS
GOOD. THE P/GRAD IS SHOWING AN 8 MB P/GRAD THROUGH 12Z AND THE LLJ
IS PROGGED TO STRENGTHEN TO AROUND 55 KTS ACROSS THE HIGHER
ELEVATIONS THROUGH THIS TIME AS WELL. NO ADJUSTMENTS WILL BE MADE TO
THIS PRODUCT.
THE DRY SLOT WORKS IN THIS AFTERNOON AND CLOUDS PRECIP WILL BE QUICK
TO END ACROSS THE SW/RN ZONES...HOWEVER THE NE/RN SECTIONS WILL HOLD
ONTO PRECIP THROUGH THE AFTERNOON. THE WEDGE ALSO BEGINS TO BREAK
DOWN AROUND NOON AND A WELL DEFINED TMB WILL DEVELOP WHILE A TRIPLE
POINT LOW TRAVERSES OVERHEAD. THUS...THUNDER HAS BEEN MAINTAINED IN
THE GRIDS BEGINNING ISOL AROUND 17Z AND CHANCE TSTMS DURING THE
AFTERNOON ACROSS THE ERN THIRD OF THE CWFA. NOT EXPECTING REALLY
DEEP OR OVERLY ORGANIZED CONVECTION...BUT WITH BULK SHEAR LEVELS
AROUND 70 KTS THERE COULD BE SOME WIND ISSUES WITH SOME OF THESE
LINES.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 330 AM EST TUESDAY...AS WE HEAD TOWARD MARCH...IT LOOKS LIKE
WE ARE HEADING TOWARD WINTER...AT LEAST OVER THE NC MTNS NEAR THE TN
BORDER. WEDNESDAY WILL SEE THE UPPER LOW MOVING SLOWLY OVER THE
UPPER OH VALLEY. THIS WILL KEEP THE FLOW MORE SW TO W ACROSS THE
WESTERN CAROLINAS DURING MOST OF THE DAY DELAYING THE ARRIVAL OF THE
REALLY COLD AIR. HOWEVER...A LARGE VORT LOBE SHOULD PINWHEEL AROUND
THE UPPER LOW AND CROSS THE FCST AREA DURING THE LATE AFTERNOON AND
EARLY EVENING. THAT FEATURE WILL BE THE VANGUARD OF THE COOLER AIR
AND WILL TURN THE FLOW MORE NORTHWESTERLY WEDNESDAY NIGHT. THIS WILL
SERVE TO CRANK UP THE NW FLOW SNOW MAKING MACHINE. POP WAS RAMPED UP
INTO THE LIKELY RANGE NEAR THE TN BORDER AND KEPT THERE THROUGH
THURSDAY NIGHT AS FLOW AND MOISTURE REMAIN VERY FAVORABLE FOR THE
PRODUCTION OF SNOW SHOWERS. ACCUMULATIONS COULD END UP BEING
SIGNIFICANT IN THE FAVORABLE UPSLOPE AREAS NEAR THE TN BORDER...BUT
THE DURATION WILL BE LONG ENOUGH THAT OUR WARNING CRITERIA MIGHT NOT
BE MET. WILL NOT ISSUE A WATCH FOR THIS EVENT BECAUSE OF THE
DURATION V. ACCUM ISSUE...BUT PLAN TO HIT IT HARD IN THE HWO. SOME
OF THE SNOW SHOWERS SHOULD REACH A BIT DEEPER INTO THE MTNS THURSDAY
NIGHT WHEN MOISTURE IS A BIT DEEPER. E OF THE MTNS...IT SEEMS
DOUBTFUL THAT ANY SHOWERS WILL BREACH CONTAINMENT AND SURVIVE E OF
THE BLUE RIDGE. INSTEAD...IT SHOULD BE DRY WITH A PARTLY
CLOUDY/MOSTLY CLEAR SKY...WITH TEMPS A BIT ABOVE NORMAL WEDNESDAY
AND THEN BELOW NORMAL THURSDAY AS THE COLDER AIR REALLY TAKES HOLD.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 AM EST TUESDAY...AS THE DEEP LOW PRESSURE SYSTEM MOVES
FARTHER OFFSHORE FROM LONG ISLAND ON FRIDAY...LOW LEVEL MOISTURE
WILL CONTINUE TO BANK UP AGAINST THE TN AND NC BORDER. THE
NORTHWEST FLOW FROM ACROSS KY AND TN WILL CONTINUE TO PRODUCE
UPSLOPE SNOW SHOWERS FRIDAY AND FRIDAY NIGHT. MEDIUM RANGE MODELS
AGREE ON A DISTURBANCE ROUNDING THE BASE OF THE 500MB TROUGH ON
SATURDAY WITH BROADER ENHANCEMENT OF MOSTLY LIGHT PRECIP ACROSS OUR
REGION. GFS HAS A 536 DECIMETER LOW CENTERED OVER THE SMOKIES AT 18Z
SATURDAY WITH A TENTH OR LESS 6-HOUR PRECIP EXTENDING OVER TO CLT.
THE NEW ECMWF CLOSES A LOW ON FRIDAY AS IT CROSSES TN AND THEN OPENS
IT ONCE IT IS OVER THE NC MTNS AT 18Z SATURDAY. THEREFORE THE TIMING
IS IN SYNC. ECMWF PRECIP IS VERY LIGHT...0.01 TO 0.03 IN 6 HOURS.
AS THIS FEATURE PASSES EAST OF OUR AREA...PRECIP ENDS EAST OF THE
MTNS SATURDAY NIGHT AND SUNDAY AND LIGHT UPSLOPE SNOW SHOWERS COME
TO AN END SUNDAY EVENING ALONG THE NC AND TN BORDER. MOST OF THE
GUIDANCE TONIGHT HAS INCREASING TEMPS BY ONE TO 3 DEGREES...BUT WITH
THE DEPTH OF THE TROUGH AND ALL OTHER LOGICAL METEOROLOGY IT SEEMS
SENSIBLE TO EVEN LOWER TEMPS A DEGREE OR TWO OVER THE WEEKEND.
AFTER THE TROUGH MOVES OFF THE EAST COAST SUNDAY NIGHT...A SHALLOW
RIDGE BUILDS OVER OUR AREA FOR MONDAY RESULTING IN SLIGHTLY HIGHER
THICKNESSES AND A BIT MILDER UNDER PLENTY OF SUNSHINE. EVEN WITH
THIS SLIGHT WARM UP...TEMPS WILL STILL BE ABOUT 8 TO 10 DEGREES
BELOW NORMAL TO START NEXT WEEK.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AT KCLT...MAJORITY OF PRECIPITATION HAS MOVED NORTH AND EAST OF THE
AIRFIELD. COLD WEDGE HAS HELD STRONG AND SFC BASED INSTABILITY NO
LONGER APPEARS TO BE A CONCERN. SOME CONVECTIVELY ENHANCED SHOWERS
ARE PRESENT ON RADAR ACROSS THE REGION BUT NO LIGHTNING STRIKES HAVE
BEEN RECORDED. INDEED A FEW SHOWERS ARE LIKELY TO MOVE THROUGH THIS
AFTERNOON POSSIBLY BRINGING IFR VSBY BUT NO THUNDER EXPECTED. IFR
CIG SHOULD HOLD ON FOR SEVERAL HOURS...ONCE SHOWER ACTIVITY
DIMINISHES CIGS MAY IMPROVE TO LOW MVFR. WINDS NELY UNDER THE WEDGE.
ONCE COLD FRONT PUSHES IN THIS EVENING THE WEDGE WILL ERODE...WINDS
WILL SWING TO SOUTHWEST AND VFR CIGS ARRIVE THEN SCATTER. SOME
POTENTIAL FOR FOG TO DEVELOP LATE TONIGHT GIVEN MOIST SOILS AND
FAIRLY MOIST LLVL PROFILES...BUT GUIDANCE KEEPS VFR VSBY THROUGH
DAYBREAK.
ELSEWHERE...WIDESPREAD SHRA WILL CONTINUE NORTH OF KCLT...AFFECTING
KHKY THIS AFTN. PASSING BANDS OF CONVECTIVE SHOWERS MAY BRIEFLY
AFFECT THE OTHER SITES AS WELL...WITH A SLIGHT CHANCE OF THUNDER.
THE SHRA MAY BRING IFR VSBY AT THEIR HEAVIEST. SHOWERS DIMINISH BY
LATE AFTN...WITH ALL TERMINALS BEING DRY OVERNIGHT. MOSTLY IFR CIGS
LOOK TO HOLD ON UNTIL COLD FRONT PUSHES WEDGE OUT OF THE PICTURE
LATE THIS AFTN IN OUR WEST AND THIS EVENING EAST. VFR STRATUS SHOULD
FILL IN BEHIND THE FRONT BUT MAY SCATTER LATE. NE WINDS UNDER THE
WEDGE WILL TURN SOUTH TO SOUTHWEST BEHIND THE FRONT.
OUTLOOK...DRY AIR ADV AND CLEARING SKIES WILL CONTINUE WED NIGHT
WITH VFR CONDS EXPECTED THROUGH THURSDAY EAST OF THE MOUNTAINS. SOME
POTENTIAL EXISTS FOR MVFR ACROSS THE NC MTNS WITH SNOW SHOWERS MID
TO LATE WEEK.
CONFIDENCE TABLE...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT HIGH 100% HIGH 90% HIGH 100% HIGH 98%
KGSP HIGH 94% HIGH 88% HIGH 98% HIGH 98%
KAVL HIGH 96% HIGH 89% MED 69% HIGH 94%
KHKY HIGH 87% HIGH 88% MED 73% HIGH 95%
KGMU MED 76% HIGH 88% HIGH 98% HIGH 98%
KAND MED 72% HIGH 91% MED 65% HIGH 95%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ033-048>052-
058-059.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...SBK/WIMBERLEY
SHORT TERM...PM
LONG TERM...DEO
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
910 AM EST TUE FEB 26 2013
.SYNOPSIS...
STRONG LOW PRESSURE WILL MOVE FROM ARKANSAS TO KENTUCKY TODAY WHILE
DRAGGING A WARM FRONT NORTH TOWARD OUR AREA. EXPECT THE WARM FRONT
TO REACH VIRGINIA LATER TONIGHT. A COLD FRONT WILL CROSS OUR REGION
FROM THE NORTHWEST LATE WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
900 AM UPDATE...BACK EDGE OF HEAVIER PCPN WILL BE NEAR DRY SLOT
EVIDENT ON WV IMAGERY. SFC OBS AND RADAR INDICATING SOME SCATTERED
SHOWERS ARE PRESENT BEHIND THE BACK EDGE. ALSO NOTING RAP SOUNDINGS
WHICH STILL SHOW INSTABILITY ABOVE WARM NOSE UNTIL MIDLEVEL COLD
ADVECTION GETS GOING THIS AFTN. THUS MAINTAINED CHC POPS BEHIND THE
SOLID PCPN SHIELD AS WELL AS THUNDER WORDING FROM MRNG PACKAGE.
REVISED TEMP TRENDS TO SLOW WARMING A BIT OVER THE NRN PIEDMONT
WHERE LIGHT ICE ACCUM STILL OCCURRING...PUTTING TEMPS MORE IN LINE
WITH 06Z NAM WHICH VERIFIED BETTER EARLIER THIS MRNG. ALLOWED WINTER
HEADLINES TO EXPIRE OVER THE SW MTNS WHERE TEMPS HAVE MOSTLY WARMED
ABV 0C...BUT EXTENDED BY ONE HOUR THE WINTER STORM WRNG UP NORTH AND
ALSO THE FZRA ADVY FOR THE FOOTHILLS THAT PREVIOUSLY EXPIRED AT 14Z.
PREV DISCUSSION...AS OF 400 AM...THE COMPLEX OCCLUDED LOW AND WEDGE
COMBO SYSTEM IS LIVING UP TO AND SURPASSING EXPECTATIONS A LITTLE
THIS MORNING. THE COOLING ACROSS THE NC MTNS AND THE AMOUNT OF
PRECIP EXPECTED THE NEXT SEVERAL HRS WILL COMBINE TO GIVE A GOOD
AMOUNT OF -FZRA ACROSS THE CENTRAL MTNS AND HIGHER ELEV OF THE SRN
FOOTHILLS...ALONG WITH THE ESCARPMENT AREA NEAR THE SC/NC BORDER.
STILL EVALUATING THE NRN MTNS AND HIGH ELEV NRN FOOTHILLS FOR A
POSSIBLE WARNING UPGRADE...BUT FOR NOW WILL COUNT OF THE PRECIP/ICE
ACCUMS REMAINING THE HIGHEST ACROSS THE AREAS TO THE SOUTH WHERE THE
BEST LIFT AND ISENT OMEGA EXIST. ALSO...WILL ADD A FREEZING RAIN
ADVISORY FOR AREAS EAST OF THE MTNS ACROSS THE NRN/SRN FOOTHILLS AND
THE NC PIEDMONT WEST OF THE I-77 CORRIDOR.
THE MODELS ARE DOING AN ADEQUATE JOB WITH THE DYNAMICS OF THIS
SYSTEM THROUGH THE NEAR TERM AND GIVE GOOD CONFIDENCE WITH THE
WARMING TAKING OVER THE LLVLS BY 14Z OR SO AND CHANGING THE MAJORITY
OF LOCALES TO ALL -RA. HOWEVER...THERE MAY BE SOME LINGERING POCKETS
OF -FZRA ACROSS ISOL MTN VALLEYS THROUGH LATE MORNING. HAVE NOTICED
THE WETBULB FREEZING ZONE EXPANDING IN COVERAGE THIS MORNING INTO
THE UPSTATE AND THREATENING AREAS AROUND CLT AND THE I-77. THIS WILL
BE MONITORED FOR A POSSIBLE FZRA ADVISORY INCLUSION.
THE HIGH WIND WARNING AND ADVISORY ACROSS THE WRN MTNS STILL LOOKS
GOOD. THE P/GRAD IS SHOWING AN 8 MB P/GRAD THROUGH 12Z AND THE LLJ
IS PROGGED TO STRENGTHEN TO AROUND 55 KTS ACROSS THE HIGHER
ELEVATIONS THROUGH THIS TIME AS WELL. NO ADJUSTMENTS WILL BE MADE TO
THIS PRODUCT.
THE DRY SLOT WORKS IN THIS AFTERNOON AND CLOUDS PRECIP WILL BE QUICK
TO END ACROSS THE SW/RN ZONES...HOWEVER THE NE/RN SECTIONS WILL HOLD
ONTO PRECIP THROUGH THE AFTERNOON. THE WEDGE ALSO BEGINS TO BREAK
DOWN AROUND NOON AND A WELL DEFINED TMB WILL DEVELOP WHILE A TRIPLE
POINT LOW TRAVERSES OVERHEAD. THUS...THUNDER HAS BEEN MAINTAINED IN
THE GRIDS BEGINNING ISOL AROUND 17Z AND CHANCE TSTMS DURING THE
AFTERNOON ACROSS THE ERN THIRD OF THE CWFA. NOT EXPECTING REALLY
DEEP OR OVERLY ORGANIZED CONVECTION...BUT WITH BULK SHEAR LEVELS
AROUND 70 KTS THERE COULD BE SOME WIND ISSUES WITH SOME OF THESE
LINES.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 330 AM EST TUESDAY...AS WE HEAD TOWARD MARCH...IT LOOKS LIKE
WE ARE HEADING TOWARD WINTER...AT LEAST OVER THE NC MTNS NEAR THE TN
BORDER. WEDNESDAY WILL SEE THE UPPER LOW MOVING SLOWLY OVER THE
UPPER OH VALLEY. THIS WILL KEEP THE FLOW MORE SW TO W ACROSS THE
WESTERN CAROLINAS DURING MOST OF THE DAY DELAYING THE ARRIVAL OF THE
REALLY COLD AIR. HOWEVER...A LARGE VORT LOBE SHOULD PINWHEEL AROUND
THE UPPER LOW AND CROSS THE FCST AREA DURING THE LATE AFTERNOON AND
EARLY EVENING. THAT FEATURE WILL BE THE VANGUARD OF THE COOLER AIR
AND WILL TURN THE FLOW MORE NORTHWESTERLY WEDNESDAY NIGHT. THIS WILL
SERVE TO CRANK UP THE NW FLOW SNOW MAKING MACHINE. POP WAS RAMPED UP
INTO THE LIKELY RANGE NEAR THE TN BORDER AND KEPT THERE THROUGH
THURSDAY NIGHT AS FLOW AND MOISTURE REMAIN VERY FAVORABLE FOR THE
PRODUCTION OF SNOW SHOWERS. ACCUMULATIONS COULD END UP BEING
SIGNIFICANT IN THE FAVORABLE UPSLOPE AREAS NEAR THE TN BORDER...BUT
THE DURATION WILL BE LONG ENOUGH THAT OUR WARNING CRITERIA MIGHT NOT
BE MET. WILL NOT ISSUE A WATCH FOR THIS EVENT BECAUSE OF THE
DURATION V. ACCUM ISSUE...BUT PLAN TO HIT IT HARD IN THE HWO. SOME
OF THE SNOW SHOWERS SHOULD REACH A BIT DEEPER INTO THE MTNS THURSDAY
NIGHT WHEN MOISTURE IS A BIT DEEPER. E OF THE MTNS...IT SEEMS
DOUBTFUL THAT ANY SHOWERS WILL BREACH CONTAINMENT AND SURVIVE E OF
THE BLUE RIDGE. INSTEAD...IT SHOULD BE DRY WITH A PARTLY
CLOUDY/MOSTLY CLEAR SKY...WITH TEMPS A BIT ABOVE NORMAL WEDNESDAY
AND THEN BELOW NORMAL THURSDAY AS THE COLDER AIR REALLY TAKES HOLD.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 AM EST TUESDAY...AS THE DEEP LOW PRESSURE SYSTEM MOVES
FARTHER OFFSHORE FROM LONG ISLAND ON FRIDAY...LOW LEVEL MOISTURE
WILL CONTINUE TO BANK UP AGAINST THE TN AND NC BORDER. THE
NORTHWEST FLOW FROM ACROSS KY AND TN WILL CONTINUE TO PRODUCE
UPSLOPE SNOW SHOWERS FRIDAY AND FRIDAY NIGHT. MEDIUM RANGE MODELS
AGREE ON A DISTURBANCE ROUNDING THE BASE OF THE 500MB TROUGH ON
SATURDAY WITH BROADER ENHANCEMENT OF MOSTLY LIGHT PRECIP ACROSS OUR
REGION. GFS HAS A 536 DECIMETER LOW CENTERED OVER THE SMOKIES AT 18Z
SATURDAY WITH A TENTH OR LESS 6-HOUR PRECIP EXTENDING OVER TO CLT.
THE NEW ECMWF CLOSES A LOW ON FRIDAY AS IT CROSSES TN AND THEN OPENS
IT ONCE IT IS OVER THE NC MTNS AT 18Z SATURDAY. THEREFORE THE TIMING
IS IN SYNC. ECMWF PRECIP IS VERY LIGHT...0.01 TO 0.03 IN 6 HOURS.
AS THIS FEATURE PASSES EAST OF OUR AREA...PRECIP ENDS EAST OF THE
MTNS SATURDAY NIGHT AND SUNDAY AND LIGHT UPSLOPE SNOW SHOWERS COME
TO AN END SUNDAY EVENING ALONG THE NC AND TN BORDER. MOST OF THE
GUIDANCE TONIGHT HAS INCREASING TEMPS BY ONE TO 3 DEGREES...BUT WITH
THE DEPTH OF THE TROUGH AND ALL OTHER LOGICAL METEOROLOGY IT SEEMS
SENSIBLE TO EVEN LOWER TEMPS A DEGREE OR TWO OVER THE WEEKEND.
AFTER THE TROUGH MOVES OFF THE EAST COAST SUNDAY NIGHT...A SHALLOW
RIDGE BUILDS OVER OUR AREA FOR MONDAY RESULTING IN SLIGHTLY HIGHER
THICKNESSES AND A BIT MILDER UNDER PLENTY OF SUNSHINE. EVEN WITH
THIS SLIGHT WARM UP...TEMPS WILL STILL BE ABOUT 8 TO 10 DEGREES
BELOW NORMAL TO START NEXT WEEK.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
AT KCLT...EXPECT THE PRECIP TO REMAIN ALL RAIN AT KCLT THIS MORNING
WITH NO GOOD COOLING TW UPSTREAM. THE PRECIP SHOULD HANG OUT FOR
MOST OF THE DAY AS A TRIPPLE POINT LOW CROSSES AND ENHANCES THE
CONVECTIVE POTENTIAL. DRY SLOT WORKS IN LATE AS THE WEDGE BOUNDARY
LIFTS NORTH...BUT CLOUDS WILL LIKELY HANG TOUGH IN THE MVFR RANGE
THIS EVENING AS DISSIPATING WEDGE MOVES SLOWLY. VFR CONDS ARE
EXPECTED AFT 02Z.
ELSEWHERE...PERIODS OF -FRZA WILL BE EXPERINCED AT KAVL AND MORE
CONTINUOUS -FZRA AT KHKY THROUGH 14Z OR SO. IMPROVING CONDS TO
MVFR/VFR ARE EXPECT AROUND 18Z EXCEPT FOR KHKY AS DRY SLOT WORKS IN
AND MOIST WEDGE LIFTS NE. WITH THE P/GRAD MAINTAINED AND EVEN
TIGHTENING A LITTLE THROUGH 18Z KAVL WILL CREATE THE POSSIBILITY OF
A WIND SHEAR CONCERN BTW 15Z AND 18Z.
OUTLOOK...DRY AIR ADV AND CLEARING SKIES WILL CONTINUE WED NIGHT
WITH VFR CONDS EXPECTED THROUGH THURSDAY EAST OF THE MOUNTAINS. SOME
POTENTIAL EXISTS FOR MVFR ACROSS THE NC MTNS WITH SNOW SHOWERS MID
TO LATE WEEK.
CONFIDENCE TABLE...
14-20Z 20-02Z 02-08Z 08-14Z
KCLT HIGH 94% HIGH 96% HIGH 90% HIGH 96%
KGSP MED 79% HIGH 90% HIGH 90% HIGH 98%
KAVL HIGH 80% MED 68% HIGH 86% HIGH 91%
KHKY HIGH 85% HIGH 94% HIGH 84% HIGH 90%
KGMU MED 79% HIGH 88% HIGH 90% HIGH 98%
KAND HIGH 88% MED 75% HIGH 96% HIGH 96%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR NCZ033-
048>052-058-059.
WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ033-048>052-
058-059.
WINTER STORM WARNING UNTIL 10 AM EST THIS MORNING FOR NCZ033-
049-050-501-503-505.
FREEZING RAIN ADVISORY UNTIL 10 AM EST THIS MORNING FOR
NCZ035>037-056-057-068-069-502-504-506-508-510.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...SBK/WIMBERLEY
SHORT TERM...PM
LONG TERM...DEO
AVIATION...SBK
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
343 AM EST TUE FEB 26 2013
.SYNOPSIS...
STRONG LOW PRESSURE WILL MOVE FROM ARKANSAS TO KENTUCKY TODAY WHILE
DRAGGING A WARM FRONT NORTH TOWARD OUR AREA. EXPECT THE WARM FRONT
TO REACH VIRGINIA LATER TONIGHT. A COLD FRONT WILL CROSS OUR REGION
FROM THE NORTHWEST LATE WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE NEAR TERM DISCUSSION WILL BE UPDATED AGAIN BY 415 AM TO
REFLECT THE NEW ADVISORY ISSUANCE AND TO UPDATE THE WWA SECTION.
AS OF 230 AM...WENT AHEAD AND ISSUED AN ICE STORM WARNING FOR A
PORTION OF THE CENTRAL MTNS AND HIGHER ELEV OF POLK AND RUTHERFORD
COUNTIES. THE MESONET OBS INDICATE FREEZING OR BELOW TEMPS ACROSS
MANY OF THE VALLEY LOCATIONS AND RIDGES AS WELL. THE INCOMING
PRECIP SHIELD HAS BECOME HEAVIER AND UNIFORMLY WIDESPREAD. EXPECT
FZRA RAIN TO CONTINUE TO AROUND DAYBREAK WITH THE HIGHEST ICE
ACCUMS ARE LIKELY AROUND SRN HENDERSON COUNTY WHERE 0.25 INCHES OR
MORE WILL ACCUMULATE IN GOOD ISENT AND MECH LIFT. OTHER AREAS IN
THE WARNING WILL ALSO SEE NEAR OR WARNING LEVEL ICE ACCUMS THROUGH
12Z. EXPECT WAA TO OVERCOME THE LLVL COLD LAYER AROUND 14Z...BUT
SOME VALLEYS COULD MAINTAIN THE FORMATION OF -FRZA INTO THE LATE
MORNING.
AS OF 100 AM...THE LATEST SFC ANALYSIS INDICATES TW TEMPS AT
FREEZING OR BELOW ACROSS THE ADV AREA AND EVEN OVER THE NRN
FOOTHILLS. WILL MONITOR THE SENSIBLE WX OVER THE NEXT FEW HRS AS THE
PRECIP SHIELD MAKES HEADWAY INTO THE FCST AREA. VERY LIGHT PRECIP
IS NOTED CURRENTLY AND EXPECT DBZ/S TO PICK UP TO AROUND 20/25
AROUND 08Z-09Z ACROSS THE NC MTNS. THE LATEST HRRR KEEPS DECENT
PRECIP ACROSS THE ADV AREA THROUGHOUT IT/S RUN...WHICH MAY LEND
SUPPORT FOR A POSSIBLE UPGRADE TO A WARNING FOR FZRA AS LONG AS LLVL
WAA DOESNT CATCH UP BY THEN. MADE MINOR TWEAKS TO THE GOING GRIDS
FOR T/TD AND WINDS...POP/WX GRIDS STILL LOOK GOOD.
REGIONAL RADAR INDICATED THAT THE SIGNIFICANT RAINFALL WAS LOCATED
ACROSS SOUTHERN AND WESTERN GA. LATEST MODEL RUNS HAVE TRENDED
SLOWER WITH THE ARRIVAL OF THE RA ACROSS THE WESTERN FA AROUND
MIDNIGHT. WIDESPREAD PRECIPITATION IS EXPECTED TO EXPAND ACROSS THE
ENTIRE CWA BY 9Z. FORECAST SOUNDINGS INDICATE THAT A DEEP WARM NOSE
WILL EXIST ACROSS THE REGION TONIGHT...WARMING ABOVE 4C AT 3 KFT BY
LATE TONIGHT. PRECIP THAT FALLS WILL BE EITHER RA OR FZRA...POSSIBLY
SOME IP AT TIMES.
OBSERVATIONS AT 10 PM INDICATE THAT NRN MTNS RANGE FROM THE MID 30S
TO U20S. HOWEVER...TEMPERATURES MAY BECOME STEADY OR GRADUALLY RISE
WITH THE ARRIVAL OF WAA AND LOWER CLOUD COVER. IN ADDITION...LLVL
FLOW...PRECIP...DEEPENING MOISTURE SHOULD RESULT IN A GRADUAL
WARMING OF DEWPOINTS OVERNIGHT. BASED ON THE MARGINAL
TEMPERATURES...FREEZING RAIN SHOULD REMAIN LIMITED TO THE EAST
FACING SLOPES OF THE MTNS FROM HENDERSON TO AVERY...ALONG WITH THE
ADJACENT FOOTHILLS. IN ADDITION...UPSLOPE FLOW MAY AID IN COOLING
TEMPERATURE ALONG THE ESCARPMENT. THESE FACTORS YIELD NEAR WARNING
CRITERIA FREEZING RAIN ALONG THE EAST FACING SLOPES...BUT LIGHT
AMOUNTS ELSEWHERE. I WILL KEEP THE WINTER WEATHER ADVISORY IN PLACE.
WINDS TONIGHT ACROSS THE MTN WILL BECOME QUITE STRONG...PRESSURE
GRADIENT ACROSS THE MTNS TIGHTENS TO AROUND 8 MBS BY 12Z. RIDGETOP
GUSTS SHOULD EXCEED 50 KTS...WITH WINDS BETWEEN 30 TO 40 KTS. THE
COMBINATION OF THE WINDS...WET GROUND...AND ICE ACCUMULATIONS MAY
YIELD TREE AND POWERLINE DAMAGE BY SUNRISE TUESDAY. I WILL UPDATE
THE NPW ALONG WITH THE HWO.
AS OF 630 PM...THE FORECAST APPEARS ON TRACK. I WILL UPDATE THE
T/TD/WINDS TO LATEST OBSERVATIONS.
AS OF 545 PM...I WILL UPDATE THE FORECAST THROUGH TUESDAY. LATEST
REGIONAL RADAR COMPOSITE INDICATES LITTLE TO NO RETURNS ACROSS THE
FORECAST AREA AND ACROSS THE UPSTREAM REGION. THEREFORE...I HAVE
SLOWED THE ARRIVAL OF CATE POPS UNTIL AFTER MIDNIGHT. THEN...ALL
SOLUTIONS INDICATE THAT WIDESPREAD PRECIP WILL OCCUR DURING THE PRE
DAWN HOURS AND EARLY DAYTIME HOURS ON TUESDAY...BEFORE A DRY SLOT
ARRIVES IN THE AFTERNOON.
THE SLOWING OF THE ARRIVAL OF POPS AND SLIGHT QPF FORECAST WILL HAVE
AN IMPACT ON THE ICE FORECAST LATE TONIGHT AND TUESDAY MORNING. THE
LATEST FORECAST WILL FEATURE VALUES APPROACHING 0.25 ALONG THE EAST
FACING SLOPES OF THE NC NRN MTNS...ELSEWHERE ACROSS THE ADJACENT
FOOTHILLS AND VALLEY...VALUES WILL REMAIN LESS THAN A TENTH OF AN
INCH. THE CURRENT WSW APPEARS WELL PLACED AND TIMED FOR ADVISORY
FREEZING RAIN. ONE NOTE...THE SREF GUIDANCE APPEARS VERY HIGH ON
FZRA AMOUNTS. THEREFORE...THE SREF PLUMES AND ANY GUIDANCE BASED ON
THE SREF WILL NOT BE CONSIDERED.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 330 AM EST TUESDAY...AS WE HEAD TOWARD MARCH...IT LOOKS LIKE
WE ARE HEADING TOWARD WINTER...AT LEAST OVER THE NC MTNS NEAR THE TN
BORDER. WEDNESDAY WILL SEE THE UPPER LOW MOVING SLOWLY OVER THE
UPPER OH VALLEY. THIS WILL KEEP THE FLOW MORE SW TO W ACROSS THE
WESTERN CAROLINAS DURING MOST OF THE DAY DELAYING THE ARRIVAL OF THE
REALLY COLD AIR. HOWEVER...A LARGE VORT LOBE SHOULD PINWHEEL AROUND
THE UPPER LOW AND CROSS THE FCST AREA DURING THE LATE AFTERNOON AND
EARLY EVENING. THAT FEATURE WILL BE THE VANGUARD OF THE COOLER AIR
AND WILL TURN THE FLOW MORE NORTHWESTERLY WEDNESDAY NIGHT. THIS WILL
SERVE TO CRANK UP THE NW FLOW SNOW MAKING MACHINE. POP WAS RAMPED UP
INTO THE LIKELY RANGE NEAR THE TN BORDER AND KEPT THERE THROUGH
THURSDAY NIGHT AS FLOW AND MOISTURE REMAIN VERY FAVORABLE FOR THE
PRODUCTION OF SNOW SHOWERS. ACCUMULATIONS COULD END UP BEING
SIGNIFICANT IN THE FAVORABLE UPSLOPE AREAS NEAR THE TN BORDER...BUT
THE DURATION WILL BE LONG ENOUGH THAT OUR WARNING CRITERIA MIGHT NOT
BE MET. WILL NOT ISSUE A WATCH FOR THIS EVENT BECAUSE OF THE
DURATION V. ACCUM ISSUE...BUT PLAN TO HIT IT HARD IN THE HWO. SOME
OF THE SNOW SHOWERS SHOULD REACH A BIT DEEPER INTO THE MTNS THURSDAY
NIGHT WHEN MOISTURE IS A BIT DEEPER. E OF THE MTNS...IT SEEMS
DOUBTFUL THAT ANY SHOWERS WILL BREACH CONTAINMENT AND SURVIVE E OF
THE BLUE RIDGE. INSTEAD...IT SHOULD BE DRY WITH A PARTLY
CLOUDY/MOSTLY CLEAR SKY...WITH TEMPS A BIT ABOVE NORMAL WEDNESDAY
AND THEN BELOW NORMAL THURSDAY AS THE COLDER AIR REALLY TAKES HOLD.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 AM EST TUESDAY...AS THE DEEP LOW PRESSURE SYSTEM MOVES
FARTHER OFFSHORE FROM LONG ISLAND ON FRIDAY...LOW LEVEL MOISTURE
WILL CONTINUE TO BANK UP AGAINST THE TN AND NC BORDER. THE
NORTHWEST FLOW FROM ACROSS KY AND TN WILL CONTINUE TO PRODUCE
UPSLOPE SNOW SHOWERS FRIDAY AND FRIDAY NIGHT. MEDIUM RANGE MODELS
AGREE ON A DISTURBANCE ROUNDING THE BASE OF THE 500MB TROUGH ON
SATURDAY WITH BROADER ENHANCEMENT OF MOSTLY LIGHT PRECIP ACROSS OUR
REGION. GFS HAS A 536 DECIMETER LOW CENTERED OVER THE SMOKIES AT 18Z
SATURDAY WITH A TENTH OR LESS 6-HOUR PRECIP EXTENDING OVER TO CLT.
THE NEW ECMWF CLOSES A LOW ON FRIDAY AS IT CROSSES TN AND THEN OPENS
IT ONCE IT IS OVER THE NC MTNS AT 18Z SATURDAY. THEREFORE THE TIMING
IS IN SYNC. ECMWF PRECIP IS VERY LIGHT...0.01 TO 0.03 IN 6 HOURS.
AS THIS FEATURE PASSES EAST OF OUR AREA...PRECIP ENDS EAST OF THE
MTNS SATURDAY NIGHT AND SUNDAY AND LIGHT UPSLOPE SNOW SHOWERS COME
TO AN END SUNDAY EVENING ALONG THE NC AND TN BORDER. MOST OF THE
GUIDANCE TONIGHT HAS INCREASING TEMPS BY ONE TO 3 DEGREES...BUT WITH
THE DEPTH OF THE TROUGH AND ALL OTHER LOGICAL METEOROLOGY IT SEEMS
SENSIBLE TO EVEN LOWER TEMPS A DEGREE OR TWO OVER THE WEEKEND.
AFTER THE TROUGH MOVES OFF THE EAST COAST SUNDAY NIGHT...A SHALLOW
RIDGE BUILDS OVER OUR AREA FOR MONDAY RESULTING IN SLIGHTLY HIGHER
THICKNESSES AND A BIT MILDER UNDER PLENTY OF SUNSHINE. EVEN WITH
THIS SLIGHT WARM UP...TEMPS WILL STILL BE ABOUT 8 TO 10 DEGREES
BELOW NORMAL TO START NEXT WEEK.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
AT KCLT...WINDS WILL REMAIN NE/LY IN MATURE WEDGE AND HAVE KEPT
PERIODIC LOW END GUSTS THROUGH 13Z. A GENERAL LOWERING OF CIGS WILL
OCCUR OVERNIGHT WITH IFR LIKELY AROUND DAYBREAK. LIGHT RAIN WILL
BECOME MORE MODERATE AND CONSTANT AROUND DAYBREAK AS WELL. THE WEDGE
WILL BREAK DOWN WITH TRIPLE POINT LOW TRACKING NE...SO EMBEDDED
CONVECTION AND TSTMS ARE PROBABLE AFT 18Z TO AROUND 20Z. A DRY SLOT
IS EXPECTED TO MAKE A PUSH TOWARD THE TERMINAL LATER IN THE
AFTERNOON...SO WILL ANTICIPATE IMPROVING CONDS TO MVFR BY 22Z AND
VFR BY 01Z.
ELSEWHERE...A GENERAL REDUCTION IN FLIGHT CATS FROM MVFR TO IFR IS
EXPECTED AT ALL TAF SITES OVERNIGHT. SOME LOW END NE GUSTS WILL
PERSIST ACROSS THE UPSTATE AS THE RAIN SHIELD BECOMES MORE MODERATE
AND WIDESPREAD. WITH THE TIGHT P/GRAD ACROSS THE MTNS...LLWS WILL BE
MAINTAINED IN THE KAVL TAF FOR A COUPLE HRS BEGINNING AT 15Z. THE
DRY SLOT WILL AFFECT THE WESTERN TAF SITES FIRST AND RETURN MVFR/VFR
CONDS AT ALL TERMINALS BY THE EARLY TO MIDDLE AFTERNOON...HOWEVER
KHKY MAY BE STUCK IN MFVR CIG WEDGE CONDS THROUGH THE EVENING.
OUTLOOK...DRY AIR ADV AND CLEARING SKIES WILL CONTINUE WED NIGHT
WITH VFR CONDS EXPECTED THROUGH THURSDAY EAST OF THE MOUNTAINS. SOME
POTENTIAL EXISTS FOR MVFR ACROSS THE NC MTNS WITH SNOW SHOWERS MID
TO LATE WEEK.
CONFIDENCE TABLE...
08-14Z 14-20Z 20-02Z 02-08Z
KCLT HIGH 83% HIGH 87% HIGH 80% HIGH 87%
KGSP MED 77% HIGH 85% MED 78% HIGH 87%
KAVL HIGH 91% HIGH 90% MED 78% HIGH 87%
KHKY HIGH 98% HIGH 86% HIGH 83% HIGH 82%
KGMU MED 77% HIGH 85% MED 77% HIGH 87%
KAND MED 60% HIGH 97% HIGH 80% HIGH 95%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR NCZ033-
048>052-058-059.
WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR NCZ033-
048>050-052-501-503-505.
WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ033-048>052-
058-059.
ICE STORM WARNING UNTIL 9 AM EST THIS MORNING FOR NCZ053-064-
065-507-509.
FREEZING RAIN ADVISORY UNTIL 9 AM EST THIS MORNING FOR NCZ035-
056-068-069-502-504-506-508-510.
SC...FREEZING RAIN ADVISORY UNTIL 9 AM EST THIS MORNING FOR SCZ002-
003.
&&
$$
SYNOPSIS...DEO
NEAR TERM...SBK
SHORT TERM...PM
LONG TERM...DEO
AVIATION...SBK
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
112 AM EST TUE FEB 26 2013
.SYNOPSIS...
NORTH OF A DEVELOPING WARM FRONT...MOISTURE WILL SPREAD ATOP OUR
REGION FROM THE GULF OF MEXICO. STRONG LOW PRESSURE WILL DRIVE
A COLD FRONT ACROSS OUR AREA ON TUESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 100 AM...THE LATEST SFC ANALYSIS INDICATES TW TEMPS AT
FREEZING OR BELOW ACROSS THE ADV AREA AND EVEN OVER THE NRN
FOOTHILLS. WILL MONITOR THE SENSIBLE WX OVER THE NEXT FEW HRS AS
THE PRECIP SHIELD MAKES HEADWAY INTO THE FCST AREA. VERY LIGHT
PRECIP IS NOTED CURRENTLY AND EXPECT DBZ/S TO PICK UP TO AROUND
20/25 AROUND 08Z-09Z ACROSS THE NC MTNS. THE LATEST HRRR KEEPS
DECENT PRECIP ACROSS THE ADV AREA THROUGHOUT IT/S RUN...WHICH MAY
LEND SUPPORT FOR A POSSIBLE UPGRADE TO A WARNING FOR FZRA AS LONG
AS LLVL WAA DOESNT CATCH UP BY THEN. MADE MINOR TWEAKS TO THE
GOING GRIDS FOR T/TD AND WINDS...POP/WX GRIDS STILL LOOK GOOD.
REGIONAL RADAR INDICATED THAT THE SIGNIFICANT RAINFALL WAS LOCATED
ACROSS SOUTHERN AND WESTERN GA. LATEST MODEL RUNS HAVE TRENDED
SLOWER WITH THE ARRIVAL OF THE RA ACROSS THE WESTERN FA AROUND
MIDNIGHT. WIDESPREAD PRECIPITATION IS EXPECTED TO EXPAND ACROSS THE
ENTIRE CWA BY 9Z. FORECAST SOUNDINGS INDICATE THAT A DEEP WARM NOSE
WILL EXIST ACROSS THE REGION TONIGHT...WARMING ABOVE 4C AT 3 KFT BY
LATE TONIGHT. PRECIP THAT FALLS WILL BE EITHER RA OR FZRA...POSSIBLY
SOME IP AT TIMES.
OBSERVATIONS AT 10 PM INDICATE THAT NRN MTNS RANGE FROM THE MID 30S
TO U20S. HOWEVER...TEMPERATURES MAY BECOME STEADY OR GRADUALLY RISE
WITH THE ARRIVAL OF WAA AND LOWER CLOUD COVER. IN ADDITION...LLVL
FLOW...PRECIP...DEEPENING MOISTURE SHOULD RESULT IN A GRADUAL
WARMING OF DEWPOINTS OVERNIGHT. BASED ON THE MARGINAL
TEMPERATURES...FREEZING RAIN SHOULD REMAIN LIMITED TO THE EAST
FACING SLOPES OF THE MTNS FROM HENDERSON TO AVERY...ALONG WITH THE
ADJACENT FOOTHILLS. IN ADDITION...UPSLOPE FLOW MAY AID IN COOLING
TEMPERATURE ALONG THE ESCARPMENT. THESE FACTORS YIELD NEAR WARNING
CRITERIA FREEZING RAIN ALONG THE EAST FACING SLOPES...BUT LIGHT
AMOUNTS ELSEWHERE. I WILL KEEP THE WINTER WEATHER ADVISORY IN PLACE.
WINDS TONIGHT ACROSS THE MTN WILL BECOME QUITE STRONG...PRESSURE
GRADIENT ACROSS THE MTNS TIGHTENS TO AROUND 8 MBS BY 12Z. RIDGETOP
GUSTS SHOULD EXCEED 50 KTS...WITH WINDS BETWEEN 30 TO 40 KTS. THE
COMBINATION OF THE WINDS...WET GROUND...AND ICE ACCUMULATIONS MAY
YIELD TREE AND POWERLINE DAMAGE BY SUNRISE TUESDAY. I WILL UPDATE
THE NPW ALONG WITH THE HWO.
AS OF 630 PM...THE FORECAST APPEARS ON TRACK. I WILL UPDATE THE
T/TD/WINDS TO LATEST OBSERVATIONS.
AS OF 545 PM...I WILL UPDATE THE FORECAST THROUGH TUESDAY. LATEST
REGIONAL RADAR COMPOSITE INDICATES LITTLE TO NO RETURNS ACROSS THE
FORECAST AREA AND ACROSS THE UPSTREAM REGION. THEREFORE...I HAVE
SLOWED THE ARRIVAL OF CATE POPS UNTIL AFTER MIDNIGHT. THEN...ALL
SOLUTIONS INDICATE THAT WIDESPREAD PRECIP WILL OCCUR DURING THE PRE
DAWN HOURS AND EARLY DAYTIME HOURS ON TUESDAY...BEFORE A DRY SLOT
ARRIVES IN THE AFTERNOON.
THE SLOWING OF THE ARRIVAL OF POPS AND SLIGHT QPF FORECAST WILL HAVE
AN IMPACT ON THE ICE FORECAST LATE TONIGHT AND TUESDAY MORNING. THE
LATEST FORECAST WILL FEATURE VALUES APPROACHING 0.25 ALONG THE EAST
FACING SLOPES OF THE NC NRN MTNS...ELSEWHERE ACROSS THE ADJACENT
FOOTHILLS AND VALLEY...VALUES WILL REMAIN LESS THAN A TENTH OF AN
INCH. THE CURRENT WSW APPEARS WELL PLACED AND TIMED FOR ADVISORY
FREEZING RAIN. ONE NOTE...THE SREF GUIDANCE APPEARS VERY HIGH ON
FZRA AMOUNTS. THEREFORE...THE SREF PLUMES AND ANY GUIDANCE BASED ON
THE SREF WILL NOT BE CONSIDERED.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
AS OF 230 PM EST MONDAY...THE SHORT TERM PERIOD BEGINS WITH AN
OCCLUDED FRONT MOVING EASTWARD AWAY FROM THE AREA ALLOWING A DRY
SLOT TO CONTINUE TO SURGE ACROSS THE REGION. HENCE...IT APPEARS THAT
THE PRECIP THREAT WILL HAVE ENDED TUE EVENING. TIME SECTIONS
INDICATE THAT LOW LEVELS REMAIN RATHER MOIST...SO MOSTLY CLOUDY
CONDITIONS WILL ONLY GRADUALLY GIVE WAY TO PARTLY CLOUDY CONDITIONS
TUE NIGHT. THERE IS SOME MODEL QPF RESPONSE IN THE SW MOUNTAINS LATE
TUE NIGHT DUE TO UPSLOPE...SO WILL HAVE SOME CHC TYPE POPS THERE.
THERMAL PROFILES INDICATE THAT ANY PRECIP WOULD BE LIGHT SNOW
SHOWERS. AS AN INTENSE UPPER LOW TRACKS INTO THE EASTERN GREAT LAKES
ON WED...A SHORT WAVE RIDGE IS FORECAST TO BUILD ACROSS THE AREA
WHICH SHOULD PRODUCE MOSTLY CLEAR CONDITIONS AND NEAR NORMAL TEMPS
EAST OF THE MOUNTAINS ...ALSO DUE IN PART TO DOWNSLOPING WINDS.
MOISTURE/CLOUDS WILL INCREASE OVER THE MOUNTAINS BY LATE IN THE DAY
AS AN UPPER TROUGH APPROACHES. SOME SCT RAIN/SNOW SHOWERS MAY
DEVELOP BY LATE WED ALONG THE TENNESSEE BORDER COUNTIES. PROFILES
CONTINUE TO MOISTEN AND COOL OVER THE MOUNTAINS WED NIGHT WITH THE
WINDS TURING MORE NW. THIS COMBINATION ALONG WITH SOME UPPER AIR
SUPPORT IS EXPECTED TO PRODUCE NUMEROUS SNOW SHOWERS ACROSS THE
MOUNTAINS...ESPECIALLY IN THE FAVORED UPSLOPE AREAS. AT LEAST SCT NW
FLOW SNOW SHOWERS WILL CONTINUE THROUGH THU AS WINDS AND MOISTURE
REMAIN FAVORABLE...THOUGH COVERAGE IS EXPECTED TO DECREASE THROUGH
THE DAY THU. SNOW TOTALS OVER THE MOUNTAINS FOR WED NIGHT AND THU
SHOULD BE IN THE 1 TO 3 INCH RANGE. STAYED CLOSE TO THE METMOS FOR
TEMPS THROUGH WED NIGHT. FOR THU...USED OUR LOW LEVEL THICKNESS
SCHEME WHICH YIELDED TEMPS BELOW GMOS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 230 PM EST MONDAY...THE DEEP LOW PRESSURE SYSTEM OVER THE NE
U.S. ON FRI WILL MOVE OFFSHORE...BUT WITH ADDITIONAL PIECES OF
SHORTWAVE ENERGY MOVING SWD THROUGH THE CENTRAL AND ERN CONUS TO
MAINTAIN THE UPPER TROUGH OVER THE AREA. AT LOW LEVELS...ENOUGH
UPSTREAM MOISTURE WILL PERSIST IN THE COLD NW FLOW TO KEEP SCATTERED
UPSLOPE SNOW SHOWERS GOING ACROSS THE WRN NC MTNS THROUGH FRIDAY.
MEANWHILE...THE STRONGEST UPSTREAM SHORTWAVE WILL DIG OVER THE LOWER
MS RIVER VALLEY...WITH THIS FEATURE LIKELY CROSSING THE EXTREME
SOUTHERN APPALACHIANS AND ADJACENT FOOTHILLS AND PIEDMONT SOMETIME
ON SAT. THE ECMWF REMAINS THE MOST VIGOROUS WITH THIS WAVE...BRIEFLY
CLOSING IT OFF ON SAT...BUT THE GFS/CMC ARE ALSO EXHIBITING BETTER
TROUGHINESS AND MOISTURE WITH THE WAVE. EVEN THE LESS AMPLIFED
MODELS APPEAR TO HAVE A FAIRLY POTENT VORT LOBE CROSSING THE
REGION...AND 850 TO 500 MB LAPSE RATES UP TO 6.5 DEG C/KM MAY
SUPPORT ISOLD TO SCT SNOW SHOWERS EAST OF THE MTNS SAT. POPS HAVE
BEEN ADJUSTED UP SLIGHTLY FROM THE PREVIOUS FORECAST.
A RETURN TO NW FLOW UPSLOPE MOISTURE WILL YIELD ADDITIONAL LIGHT MTN
SNOW SHOWER ACCUMS INTO SUNDAY AS THE UPPER TROUGH AXIS BECOMES
REINFORCED BY ADDITIONAL SHORTWAVE ENERGY. BETTER DRYING SHOULD THEN
SET IN THROUGH MON AS HIGH PRESSURE BUILDS IN FROM THE WEST. WILL
CONTINUE TO FEATURE MINS 5 TO 10 DEGREES BELOW NORMAL...WITH MAXES
10 TO 15 DEGREES BELOW NORMAL...THROUGH THE PERIOD.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AT KCLT...WINDS WILL REMAIN NE/LY IN MATURE WEDGE AND HAVE KEPT
PERIODIC LOW END GUSTS THROUGH 13Z. A GENERAL LOWERING OF CIGS WILL
OCCUR OVERNIGHT WITH IFR LIKELY AROUND DAYBREAK. LIGHT RAIN WILL
BECOME MORE MODERATE AND CONSTANT AROUND DAYBREAK AS WELL. THE WEDGE
WILL BREAK DOWN WITH TRIPLE POINT LOW TRACKING NE...SO EMBEDDED
CONVECTION AND TSTMS ARE PROBABLE AFT 18Z TO AROUND 20Z. A DRY SLOT
IS EXPECTED TO MAKE A PUSH TOWARD THE TERMINAL LATER IN THE
AFTERNOON...SO WILL ANTICIPATE IMPROVING CONDS TO MVFR BY 22Z AND
VFR BY 01Z.
ELSEWHERE...A GENERAL REDUCTION IN FLIGHT CATS FROM MVFR TO IFR IS
EXPECTED AT ALL TAF SITES OVERNIGHT. SOME LOW END NE GUSTS WILL
PERSIST ACROSS THE UPSTATE AS THE RAIN SHIELD BECOMES MORE MODERATE
AND WIDESPREAD. WITH THE TIGHT P/GRAD ACROSS THE MTNS...LLWS WILL BE
MAINTAINED IN THE KAVL TAF FOR A COUPLE HRS BEGINNING AT 15Z. THE
DRY SLOT WILL AFFECT THE WESTERN TAF SITES FIRST AND RETURN MVFR/VFR
CONDS AT ALL TERMINALS BY THE EARLY TO MIDDLE AFTERNOON...HOWEVER
KHKY MAY BE STUCK IN MFVR CIG WEDGE CONDS THROUGH THE EVENING.
OUTLOOK...DRY AIR ADV AND CLEARING SKIES WILL CONTINUE WED NIGHT
WITH VFR CONDS EXPECTED THROUGH THURSDAY EAST OF THE MOUNTAINS. SOME
POTENTIAL EXISTS FOR MVFR ACROSS THE NC MTNS WITH SNOW SHOWERS MID
TO LATE WEEK.
CONFIDENCE TABLE...
06-12Z 12-18Z 18-24Z 00-06Z
KCLT HIGH 84% HIGH 85% HIGH 86% HIGH 82%
KGSP HIGH 95% HIGH 84% HIGH 86% HIGH 80%
KAVL HIGH 91% HIGH 100% MED 76% HIGH 85%
KHKY HIGH 86% HIGH 90% HIGH 86% MED 76%
KGMU HIGH 95% HIGH 84% HIGH 84% HIGH 80%
KAND LOW 49% HIGH 96% HIGH 83% HIGH 87%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR NCZ033-
048>050-052-053-064-065-501-503-505-507-509.
HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR NCZ033-
048>052-058-059.
WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ033-048>052-
058-059.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...SBK/WIMBERLEY
SHORT TERM...LG
LONG TERM...HG
AVIATION...SBK
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
110 AM EST TUE FEB 26 2013
.SYNOPSIS...
NORTH OF A DEVELOPING WARM FRONT...MOISTURE WILL SPREAD ATOP OUR
REGION FROM THE GULF OF MEXICO. STRONG LOW PRESSURE WILL DRIVE
A COLD FRONT ACROSS OUR AREA ON TUESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 200 AM...THE LATEST SFC ANALYSIS INDICATES TW TEMPS AT
FREEZING OR BELOW ACROSS THE ADV AREA AND EVEN OVER THE NRN
FOOTHILLS. WILL MONITOR THE SENSIBLE WX OVER THE NEXT FEW HRS AS THE
PRECIP SHIELD MAKES HEADWAY INTO THE FCST AREA. VERY LIGHT PRECIP
IS NOTED CURRENTLY AND EXPECT DBZ/S TO PICK UP TO AROUND 20/25
AROUND 08Z-09Z ACROSS THE NC MTNS. THE LATEST HRRR KEEPS DECENT
PRECIP ACROSS THE ADV AREA THROUGHOUT IT/S RUN...WHICH MAY LEND
SUPPORT FOR A POSSIBLE UPGRADE TO A WARNING FOR FZRA AS LONG AS LLVL
WAA DOESNT CATCH UP BY THEN. MADE MINOR TWEAKS TO THE GOING GRIDS
FOR T/TD AND WINDS...POP/WX GRIDS STILL LOOK GOOD.
REGIONAL RADAR INDICATED THAT THE SIGNIFICANT RAINFALL WAS LOCATED
ACROSS SOUTHERN AND WESTERN GA. LATEST MODEL RUNS HAVE TRENDED
SLOWER WITH THE ARRIVAL OF THE RA ACROSS THE WESTERN FA AROUND
MIDNIGHT. WIDESPREAD PRECIPITATION IS EXPECTED TO EXPAND ACROSS THE
ENTIRE CWA BY 9Z. FORECAST SOUNDINGS INDICATE THAT A DEEP WARM NOSE
WILL EXIST ACROSS THE REGION TONIGHT...WARMING ABOVE 4C AT 3 KFT BY
LATE TONIGHT. PRECIP THAT FALLS WILL BE EITHER RA OR FZRA...POSSIBLY
SOME IP AT TIMES.
OBSERVATIONS AT 10 PM INDICATE THAT NRN MTNS RANGE FROM THE MID 30S
TO U20S. HOWEVER...TEMPERATURES MAY BECOME STEADY OR GRADUALLY RISE
WITH THE ARRIVAL OF WAA AND LOWER CLOUD COVER. IN ADDITION...LLVL
FLOW...PRECIP...DEEPENING MOISTURE SHOULD RESULT IN A GRADUAL
WARMING OF DEWPOINTS OVERNIGHT. BASED ON THE MARGINAL
TEMPERATURES...FREEZING RAIN SHOULD REMAIN LIMITED TO THE EAST
FACING SLOPES OF THE MTNS FROM HENDERSON TO AVERY...ALONG WITH THE
ADJACENT FOOTHILLS. IN ADDITION...UPSLOPE FLOW MAY AID IN COOLING
TEMPERATURE ALONG THE ESCARPMENT. THESE FACTORS YIELD NEAR WARNING
CRITERIA FREEZING RAIN ALONG THE EAST FACING SLOPES...BUT LIGHT
AMOUNTS ELSEWHERE. I WILL KEEP THE WINTER WEATHER ADVISORY IN PLACE.
WINDS TONIGHT ACROSS THE MTN WILL BECOME QUITE STRONG...PRESSURE
GRADIENT ACROSS THE MTNS TIGHTENS TO AROUND 8 MBS BY 12Z. RIDGETOP
GUSTS SHOULD EXCEED 50 KTS...WITH WINDS BETWEEN 30 TO 40 KTS. THE
COMBINATION OF THE WINDS...WET GROUND...AND ICE ACCUMULATIONS MAY
YIELD TREE AND POWERLINE DAMAGE BY SUNRISE TUESDAY. I WILL UPDATE
THE NPW ALONG WITH THE HWO.
AS OF 630 PM...THE FORECAST APPEARS ON TRACK. I WILL UPDATE THE
T/TD/WINDS TO LATEST OBSERVATIONS.
AS OF 545 PM...I WILL UPDATE THE FORECAST THROUGH TUESDAY. LATEST
REGIONAL RADAR COMPOSITE INDICATES LITTLE TO NO RETURNS ACROSS THE
FORECAST AREA AND ACROSS THE UPSTREAM REGION. THEREFORE...I HAVE
SLOWED THE ARRIVAL OF CATE POPS UNTIL AFTER MIDNIGHT. THEN...ALL
SOLUTIONS INDICATE THAT WIDESPREAD PRECIP WILL OCCUR DURING THE PRE
DAWN HOURS AND EARLY DAYTIME HOURS ON TUESDAY...BEFORE A DRY SLOT
ARRIVES IN THE AFTERNOON.
THE SLOWING OF THE ARRIVAL OF POPS AND SLIGHT QPF FORECAST WILL HAVE
AN IMPACT ON THE ICE FORECAST LATE TONIGHT AND TUESDAY MORNING. THE
LATEST FORECAST WILL FEATURE VALUES APPROACHING 0.25 ALONG THE EAST
FACING SLOPES OF THE NC NRN MTNS...ELSEWHERE ACROSS THE ADJACENT
FOOTHILLS AND VALLEY...VALUES WILL REMAIN LESS THAN A TENTH OF AN
INCH. THE CURRENT WSW APPEARS WELL PLACED AND TIMED FOR ADVISORY
FREEZING RAIN. ONE NOTE...THE SREF GUIDANCE APPEARS VERY HIGH ON
FZRA AMOUNTS. THEREFORE...THE SREF PLUMES AND ANY GUIDANCE BASED ON
THE SREF WILL NOT BE CONSIDERED.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
AS OF 230 PM EST MONDAY...THE SHORT TERM PERIOD BEGINS WITH AN
OCCLUDED FRONT MOVING EASTWARD AWAY FROM THE AREA ALLOWING A DRY
SLOT TO CONTINUE TO SURGE ACROSS THE REGION. HENCE...IT APPEARS THAT
THE PRECIP THREAT WILL HAVE ENDED TUE EVENING. TIME SECTIONS
INDICATE THAT LOW LEVELS REMAIN RATHER MOIST...SO MOSTLY CLOUDY
CONDITIONS WILL ONLY GRADUALLY GIVE WAY TO PARTLY CLOUDY CONDITIONS
TUE NIGHT. THERE IS SOME MODEL QPF RESPONSE IN THE SW MOUNTAINS LATE
TUE NIGHT DUE TO UPSLOPE...SO WILL HAVE SOME CHC TYPE POPS THERE.
THERMAL PROFILES INDICATE THAT ANY PRECIP WOULD BE LIGHT SNOW
SHOWERS. AS AN INTENSE UPPER LOW TRACKS INTO THE EASTERN GREAT LAKES
ON WED...A SHORT WAVE RIDGE IS FORECAST TO BUILD ACROSS THE AREA
WHICH SHOULD PRODUCE MOSTLY CLEAR CONDITIONS AND NEAR NORMAL TEMPS
EAST OF THE MOUNTAINS ...ALSO DUE IN PART TO DOWNSLOPING WINDS.
MOISTURE/CLOUDS WILL INCREASE OVER THE MOUNTAINS BY LATE IN THE DAY
AS AN UPPER TROUGH APPROACHES. SOME SCT RAIN/SNOW SHOWERS MAY
DEVELOP BY LATE WED ALONG THE TENNESSEE BORDER COUNTIES. PROFILES
CONTINUE TO MOISTEN AND COOL OVER THE MOUNTAINS WED NIGHT WITH THE
WINDS TURING MORE NW. THIS COMBINATION ALONG WITH SOME UPPER AIR
SUPPORT IS EXPECTED TO PRODUCE NUMEROUS SNOW SHOWERS ACROSS THE
MOUNTAINS...ESPECIALLY IN THE FAVORED UPSLOPE AREAS. AT LEAST SCT NW
FLOW SNOW SHOWERS WILL CONTINUE THROUGH THU AS WINDS AND MOISTURE
REMAIN FAVORABLE...THOUGH COVERAGE IS EXPECTED TO DECREASE THROUGH
THE DAY THU. SNOW TOTALS OVER THE MOUNTAINS FOR WED NIGHT AND THU
SHOULD BE IN THE 1 TO 3 INCH RANGE. STAYED CLOSE TO THE METMOS FOR
TEMPS THROUGH WED NIGHT. FOR THU...USED OUR LOW LEVEL THICKNESS
SCHEME WHICH YIELDED TEMPS BELOW GMOS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 230 PM EST MONDAY...THE DEEP LOW PRESSURE SYSTEM OVER THE NE
U.S. ON FRI WILL MOVE OFFSHORE...BUT WITH ADDITIONAL PIECES OF
SHORTWAVE ENERGY MOVING SWD THROUGH THE CENTRAL AND ERN CONUS TO
MAINTAIN THE UPPER TROUGH OVER THE AREA. AT LOW LEVELS...ENOUGH
UPSTREAM MOISTURE WILL PERSIST IN THE COLD NW FLOW TO KEEP SCATTERED
UPSLOPE SNOW SHOWERS GOING ACROSS THE WRN NC MTNS THROUGH FRIDAY.
MEANWHILE...THE STRONGEST UPSTREAM SHORTWAVE WILL DIG OVER THE LOWER
MS RIVER VALLEY...WITH THIS FEATURE LIKELY CROSSING THE EXTREME
SOUTHERN APPALACHIANS AND ADJACENT FOOTHILLS AND PIEDMONT SOMETIME
ON SAT. THE ECMWF REMAINS THE MOST VIGOROUS WITH THIS WAVE...BRIEFLY
CLOSING IT OFF ON SAT...BUT THE GFS/CMC ARE ALSO EXHIBITING BETTER
TROUGHINESS AND MOISTURE WITH THE WAVE. EVEN THE LESS AMPLIFED
MODELS APPEAR TO HAVE A FAIRLY POTENT VORT LOBE CROSSING THE
REGION...AND 850 TO 500 MB LAPSE RATES UP TO 6.5 DEG C/KM MAY
SUPPORT ISOLD TO SCT SNOW SHOWERS EAST OF THE MTNS SAT. POPS HAVE
BEEN ADJUSTED UP SLIGHTLY FROM THE PREVIOUS FORECAST.
A RETURN TO NW FLOW UPSLOPE MOISTURE WILL YIELD ADDITIONAL LIGHT MTN
SNOW SHOWER ACCUMS INTO SUNDAY AS THE UPPER TROUGH AXIS BECOMES
REINFORCED BY ADDITIONAL SHORTWAVE ENERGY. BETTER DRYING SHOULD THEN
SET IN THROUGH MON AS HIGH PRESSURE BUILDS IN FROM THE WEST. WILL
CONTINUE TO FEATURE MINS 5 TO 10 DEGREES BELOW NORMAL...WITH MAXES
10 TO 15 DEGREES BELOW NORMAL...THROUGH THE PERIOD.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AT KCLT...WINDS WILL REMAIN NE/LY IN MATURE WEDGE AND HAVE KEPT
PERIODIC LOW END GUSTS THROUGH 13Z. A GENERAL LOWERING OF CIGS WILL
OCCUR OVERNIGHT WITH IFR LIKELY AROUND DAYBREAK. LIGHT RAIN WILL
BECOME MORE MODERATE AND CONSTANT AROUND DAYBREAK AS WELL. THE WEDGE
WILL BREAK DOWN WITH TRIPLE POINT LOW TRACKING NE...SO EMBEDDED
CONVECTION AND TSTMS ARE PROBABLE AFT 18Z TO AROUND 20Z. A DRY SLOT
IS EXPECTED TO MAKE A PUSH TOWARD THE TERMINAL LATER IN THE
AFTERNOON...SO WILL ANTICIPATE IMPROVING CONDS TO MVFR BY 22Z AND
VFR BY 01Z.
ELSEWHERE...A GENERAL REDUCTION IN FLIGHT CATS FROM MVFR TO IFR IS
EXPECTED AT ALL TAF SITES OVERNIGHT. SOME LOW END NE GUSTS WILL
PERSIST ACROSS THE UPSTATE AS THE RAIN SHIELD BECOMES MORE MODERATE
AND WIDESPREAD. WITH THE TIGHT P/GRAD ACROSS THE MTNS...LLWS WILL BE
MAINTAINED IN THE KAVL TAF FOR A COUPLE HRS BEGINNING AT 15Z. THE
DRY SLOT WILL AFFECT THE WESTERN TAF SITES FIRST AND RETURN MVFR/VFR
CONDS AT ALL TERMINALS BY THE EARLY TO MIDDLE AFTERNOON...HOWEVER
KHKY MAY BE STUCK IN MFVR CIG WEDGE CONDS THROUGH THE EVENING.
OUTLOOK...DRY AIR ADV AND CLEARING SKIES WILL CONTINUE WED NIGHT
WITH VFR CONDS EXPECTED THROUGH THURSDAY EAST OF THE MOUNTAINS. SOME
POTENTIAL EXISTS FOR MVFR ACROSS THE NC MTNS WITH SNOW SHOWERS MID
TO LATE WEEK.
CONFIDENCE TABLE...
06-12Z 12-18Z 18-24Z 00-06Z
KCLT HIGH 84% HIGH 85% HIGH 86% HIGH 82%
KGSP HIGH 95% HIGH 84% HIGH 86% HIGH 80%
KAVL HIGH 91% HIGH 100% MED 76% HIGH 85%
KHKY HIGH 86% HIGH 90% HIGH 86% MED 76%
KGMU HIGH 95% HIGH 84% HIGH 84% HIGH 80%
KAND LOW 49% HIGH 96% HIGH 83% HIGH 87%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR NCZ033-
048>050-052-053-064-065-501-503-505-507-509.
HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR NCZ033-
048>052-058-059.
WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ033-048>052-
058-059.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...SBK/WIMBERLEY
SHORT TERM...LG
LONG TERM...HG
AVIATION...SBK
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
318 PM CST TUE FEB 26 2013
.DISCUSSION...
IT HAS BEEN A COLD...CLOUDY...DAMP...WINDY DAY ACROSS THE
MIDSOUTH. TEMPERATURES ARE GENERALLY 12 TO 18 DEGREES COLDER THAN
THIS TIME YESTERDAY...GENERALLY IN THE LOW 40S. STEADY 15-20 MPH
WIND ALONG WITH HIGH MOISTURE HAS MADE IT FEEL EVEN COLDER.
UNFORTUNATELY NO RELIEF IN THE WAY. NO SUBSTANTIAL WARMING IS
EXPECTED OVER THE NEXT SEVERAL DAYS.
TONIGHT...CLOUDS WILL LINGER ACROSS MOST OF THE AREA. AS THE UPPER
LEVEL LOW WHICH BROUGHT US THE PRECIPITATION YESTERDAY AND TODAY
SHIFTS INTO THE OHIO VALLEY...A VERY WEAK SHORTWAVE RIDGE WILL
SHIFT ACROSS THE MIDSOUTH. PORTIONS OF NORTH MISSISSIPPI AND EAST
CENTRAL ARKANSAS MAY SEE SOME TEMPORARY CLEARING...BUT IT WILL BE
SHORT LIVED AS A STRONG VORT MAX TRACKS OUT OF OKLAHOMA ENHANCING
CLOUD COVER AREA WIDE ONCE AGAIN.
WEST FLOW WILL TRANSITION TO NORTHWEST FLOW ON WEDNESDAY. THE
STORM TRACK WILL BE TO OUR NORTHWEST WEDNESDAY...BUT CLOSE ENOUGH
TO KEEP SKIES CLOUDY ACROSS MOST OF THE AREA. HIGHS MAY GET INTO
THE LOW 50S IN NORTH MISSISSIPPI...BUT THE NORTHERN HALF OF THE
MIDSOUTH WHERE CLOUDS WILL BE MORE ABUNDANT...WILL STRUGGLE TO GET
OUT OF THE 40S.
A BROAD POSITIVELY TILTED LONGWAVE TROUGH WILL DIG INTO THE
SOUTHERN PLAINS THURSDAY INTO FRIDAY. A CUTOFF LOW WILL DEVELOP
AND TRACK FROM EAST KANSAS TO NEAR THE MEMPHIS AREA FRIDAY INTO
SATURDAY MORNING. SUFFICIENT MOISTURE SHOULD BE IN PLACE AHEAD OF
THIS SYSTEM RESULTING IN RAIN SHOWERS THURSDAY...MOST LIKELY IN
WEST TENNESSEE...NORTHEAST ARKANSAS AND THE MISSOURI BOOTHEEL. AS
THE LOW GETS CLOSER AND TEMPERATURES DROP THURSDAY
NIGHT...SHOWERS MAY CHANGE OVER TO SNOW. RAIN OR SNOW LOOKS LIKE A
GOOD BET FRIDAY ACROSS THE NORTHERN HALF OF THE MIDSOUTH. WE MAY
SEE SEVERAL PHASE CHANGES FROM SNOW TO RAIN AND BACK TO SNOW ON
FRIDAY...ESPECIALLY IN PORTIONS OF TENNESSEE. WILL MAINTAIN LIGHT
SNOW AREA WIDE FRIDAY NIGHT INTO SATURDAY AS THE LOW TRACKS
DIRECTLY OVER THE MIDSOUTH. WE HAVE LOWS SATURDAY MORNING 1-4
DEGREES BELOW FREEZING...AND HIGHS AROUND 40...SO ONCE AGAIN
PRECIPITATION WILL LIKELY CHANGE PHASES...POSSIBLY SEVERAL TIMES.
THE TROUGH AXIS WILL SHIFT INTO CENTRAL TENNESSEE AND ALABAMA
SUNDAY NIGHT LIKELY MARKING THE END OF OUR PRECIPITATION.
HOWEVER...DEPENDING ON THE EXACT TRACK OF THE UPPER LOW...WE COULD
SEE ADDITIONAL WRAP AROUND SHOWERS SATURDAY NIGHT. GRADUAL
IMPROVING CONDITIONS ARE EXPECTED SUNDAY INTO NEXT WEEK...BUT
TEMPERATURES WILL REMAIN SEASONABLY COLD. HIGHS MONDAY ARE ONLY
EXPECTED TO BE IN THE MIDDLE 50S AT THE WARMEST LOCATIONS WITH THE
COOLER AREAS POSSIBLY STILL IN THE 40S.
&&
.AVIATION...
18Z TAF SET
MVFR CIGS WILL REMAIN OVER THE MIDSOUTH THROUGH AT LEAST 7-8Z AS
UPPER LOW PUSHES INTO THE OHIO VALLEY. LATEST RUC KEEPS CIGS
LONGER WHICH WOULD NOT BE SURPRISED IF THIS OCCURS AS ANOTHER
SHORTWAVE WILL ROTATE INTO THE MIDSOUTH AROUND 12Z. A FEW SHRAS
WILL BE POSSIBLE THIS AFTERNOON ACROSS THE AREA THUS WILL
CONTINUE WITH VCSH WORDING IN THE TAF. SOME SNOWFLAKES COULD MIX IN
AT KJBR AS COLDER AIR FILTERS INTO THE AREA. STRONG SW WINDS OF
12-20 KTS WITH HIGHER GUSTS WILL CONTINUE THROUGH EARLY THIS
EVENING. SPEEDS WILL GRADUALLY BEGIN DIMINISHING AFTER 1-3Z.
SPEEDS WILL PICK BACK UP AROUND 15Z AS DIRECTION BECOMES MORE W OR
NW.
KRM
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 34 50 34 46 / 10 10 10 10
MKL 33 47 33 45 / 10 10 10 20
JBR 33 47 33 45 / 10 10 10 20
TUP 34 54 34 48 / 10 10 10 10
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
1118 AM CST TUE FEB 26 2013
.UPDATE... /ISSUED 1049 AM CST TUE FEB 26 2013/
FORECAST LOOKS TO BE IN GOOD SHAPE. LIGHT RAIN IS FALLING ACROSS
MUCH OF THE MIDSOUTH RESULTING IN MINIMAL ACCUMULATION. RAIN WILL
CONTINUE THIS AFTERNOON...BUT LIKELY BECOME CONFINED TO THE
NORTHERN HALF OF THE CWA. LOWERED AFTERNOON POPS SLIGHTLY. DESPITE
RAIN ON RADAR...ACCUMULATING RAIN IS QUESTIONABLE.
OTHERWISE...BREEZY AND COOL CONDITIONS WILL CONTINUE
TODAY...ABUNDANT MOISTURE AND LACK OF SUNSHINE WILL MAKE
CONDITIONS FEEL EVEN COLDER.
&&
.DISCUSSION... /ISSUED 310 AM CST TUE FEB 26 2013/
CURRENTLY SURFACE LOW CENTER WAS LOCATED JUST NORTH OF JONESBORO
WITH AN OCCLUDED FRONT SWUNG SOUTHEAST FROM DYERSBURG TENNESSEE TO
JUST EAST OF TUPELO MISSISSIPPI. THE UPPER LEVEL CENTER SEEN ON
WATER VAPOR IMAGERY WAS LOCATED NEAR LITTLE ROCK. WINDS TO THE
EAST OF THE FRONT WERE SOUTHEAST AROUND 10 KTS...WITH RADAR
SHOWING A BAND OF RAIN SLOWLY DIMINISHING IN COVERAGE AND
INTENSITY. BEHIND THE FRONT...WINDS VEER MORE SOUTHWESTERLY WITH
DRY CONDITIONS. TEMPERATURES ACROSS THE MIDSOUTH AS OF 3 AM RANGED
FROM THE MID 40S TO MID 50S. DUE TO A DRIER RADAR TRENDS HAVE
UPDATED THE CURRENT FORECAST TO LOWER RAIN CHANCES BETWEEN 3 AND 6
AM THIS MORNING.
FOR TODAY MODELS ARE IN VERY GOOD AGREEMENT THAT THE MIDSOUTH WILL
REMAIN CLOUDY AND COOL WITH SCATTERED SHOWERS REDEVELOPING AS THE
UPPER LOW TRACKS SLOWLY TO THE LOWER OHIO VALLEY. BEST CHANCE FOR
ADDITIONAL MEASURABLE RAINFALL WILL BE ACROSS THE NORTH. SOUTHWEST
WINDS WILL INCREASE BEFORE NOON WITH GUSTS TO NEAR 30MPH. NOT MUCH
CHANGE IS ANTICIPATED TONIGHT WITH THE EXCEPTION OF SLIGHTLY DRIER
AIR MOVING IN FROM THE WEST. CAA WILL KEEP TEMPERATURES FAIRLY
STEADY IN THE 40S...TO LOW 50S FOR HIGHS. LATER TONIGHT FEEL THAT
STRATOCUMULUS CLOUD DECK WILL LINGER OVER THE REGION...KEEPING
TEMPERATURES ABOVE FREEZING.
THE UPPER LEVEL LOW WILL MOVE UP THE OHIO RIVER ON WEDNESDAY AND
SLOWLY BEGIN TO FILL. EXTENDING FROM THE LOW WILL BE HIGHLY POSITIVE
TILTED TROUGH BACK WEST TO OKLAHOMA. THIS PATTERN WILL CONTINUE TO
KEEP THE MIDSOUTH CLOUDY AND COOL...WITH A SLIGHT CHANCE FOR
BRIEF RAIN SHOWER OVER THE NORTH. TEMPERATURES WILL RUN ABOUT TEN
DEGREES BELOW NORMAL. THE TROUGH WILL PUSH SOUTHEAST THROUGH THE
AREA WEDNESDAY NIGHT WILL A SLIGHT SURFACE REFLECTION SHIFTING
WINDS MORE NORTHWESTERLY. FROM THIS...THE UPPER LEVEL PATTERN
WILL BECOME MORE MERIDIONAL...SO HAVE SLIGHTLY LOWERED THE CURRENT
HIGHS FOR THURSDAY...AS THIS WILL BE THE START OF AN UPCOMING
COLD SNAP FOR THE ENTIRE EASTERN HALF OF THE U.S.
THE BRUNT OF THE COLD AIR WILL ARRIVE ON FRIDAY AND PERSIST
THROUGH SATURDAY WITH 925MB TEMPERATURES FALLING FROM -2C TO -8C.
THIS IS IN RESPONSE TO A MORE INTENSE SHORTWAVE DROPPING INTO THE
BACKSIDE OF THE EASTERN TROUGH. THE GFS AND EURO ARE IN AGREEMENT
THAT A NEWLY FORMED CLOSED LOW WILL EMERGE FROM THIS SHORTWAVE
RIGHT OVERHEAD. MOISTURE WITH THIS DEVELOPMENT FOR NOW APPEARS
STARVED...SO HAVE KEPT POPS LOW. HOWEVER...TEMPERATURES WILL
SUPPORT A LIGHT RAIN AND SNOW MIX DURING THE DAY NORTH OF THE
TENNESSEE AND MISSISSIPPI STATE LINE...WITH ALL SNOW FRIDAY NIGHT.
MINOR ACCUMULATIONS WILL BE POSSIBLE. NOT MUCH CHANGE IS EXPECTED
ON SATURDAY WITH HIGHS EVEN A FEW DEGREES COLDER AND THE CONTINUED
CHANCE FOR A SNOW FLURRY. WITH THAT BEING SAID ONE COULD EITHER
SAY MARCH WILL BE COMING IN LIKE A LION...OR IS THIS THE FIRST
WEEKEND IN JANUARY?
EXTENDED PERIOD...SOME MODERATION IN TEMPERATURES WILL BE SEEN ON
SUNDAY AND MONDAY...BUT THEY WILL STILL BE BELOW NORMAL. NEXT
STORM WILL DIVE SOUTHEAST FROM THE UPPER HIGH PLAINS. LOW LEVEL
SOUTH WINDS WILL BRING BETTER MOISTURE TO THE MIDSOUTH MONDAY
NIGHT AND TUESDAY. THUS THIS CLIPPER TYPE EVENT WILL BRING A BRIEF
INCREASE IN TEMPERATURES AND RAIN CHANCES TO THE REGION.
JAB
&&
.AVIATION...
18Z TAF SET
MVFR CIGS WILL REMAIN OVER THE MIDSOUTH THROUGH AT LEAST 7-8Z AS
UPPER LOW PUSHES INTO THE OHIO VALLEY. LATEST RUC KEEPS CIGS
LONGER WHICH WOULD NOT BE SURPRISED IF THIS OCCURS AS ANOTHER
SHORTWAVE WILL ROTATE INTO THE MIDSOUTH AROUND 12Z. A FEW SHRAS
WILL BE POSSIBLE THIS AFTERNOON ACROSS THE AREA THUS WILL
CONTINUE WITH VCSH WORDING IN THE TAF. SOME SNOWFLAKES COULD MIX IN
AT KJBR AS COLDER AIR FILTERS INTO THE AREA. STRONG SW WINDS OF
12-20 KTS WITH HIGHER GUSTS WILL CONTINUE THROUGH EARLY THIS
EVENING. SPEEDS WILL GRADUALLY BEGIN DIMINISHING AFTER 1-3Z.
SPEEDS WILL PICK BACK UP AROUND 15Z AS DIRECTION BECOMES MORE W OR
NW.
KRM
&&
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 49 36 50 35 / 40 10 10 10
MKL 49 35 47 34 / 40 10 10 10
JBR 48 35 47 34 / 60 10 10 10
TUP 48 36 54 35 / 30 10 10 10
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1107 PM CST MON FEB 25 2013
.AVIATION...
STRONG WEST/NORTHWEST WINDS CONTINUE ACROSS THE AREA. CURRENT
SPEEDS ARE SUSTAINED AROUND 25 KNOTS WITH GUSTS AROUND 35 KNOTS
AND THINK THESE SPEEDS WILL HOLD FOR MOST OF THE NIGHT. DIRECTION
IS STEADY...AROUND 300 DEGREES. WINDS SHOULD VEER A BIT BY MORNING
WITH SPEEDS SLOWLY DECREASING AFTER SUNRISE. BY SUNSET
TOMORROW...GRADIENT WILL FINALLY SLACKEN AND SPEEDS WILL DROP
BELOW 10 KNOTS.
MVFR CIGS ARE IN PLACE ACROSS THE METROPLEX WITH BASES AROUND
2KFT. FOR WACO...VFR CIGS ARE CURRENTLY PREVAILING AND WILL KEEP
THE CIGS AT 3.5KFT. COULD SEE MVFR OVERNIGHT...BUT CONFIDENCE
WASNT HIGH ENOUGH TO MENTION AT THIS TIME. CIGS SHOULD SCATTER
ACROSS THE AREA AROUND SUNRISE...WHEN DRIER AIR FILTERS INTO THE
REGION.
HAMPSHIRE
&&
.UPDATE...
PREVIOUS FRONTOGENETICAL SNOW BAND THAT MOVED THROUGH MONTAGUE
COUNTY AN HOUR OR SO AGO HAS WEAKENED CONSIDERABLY...AS RETURNS
VIA CLEAR AIR MODE ON RADAR AND DUAL POL PRODUCTS INDICATE. HIGH-
RES RAP AND WRF MODELS ALSO INDICATE THIS TREND...AS ISENTROPIC
DOWNGLIDE AND SUBSIDENCE CONTINUE TO WEAKEN RETURNS ACROSS NORTH
TEXAS IN WAKE OF THE MID LEVEL LOW MOVING INTO SOUTHEAST OKLAHOMA
THIS EVENING. MODEL SOUNDINGS DO INDICATE THE TOP-DOWN DRYING OF
THE COLUMN BY MID EVENING INDICATIVE OF SUBSIDENCE WITH DENDRITE
SEEDING FROM THE MID AND UPPER LEVELS NO LONGER AVAILABLE.
WE DID LEAVE LOW CHANCES OF A VERY LIGHT RAIN/SNOW MIX OR A MENTION
OF SPRINKLES OR FLURRIES WITH ONLY SHALLOW MOISTURE BEING LEFT
OVER THROUGH THE OVERNIGHT. WE ARE CANCELING THE WINTER WEATHER
ADVISORY FOR OUR NORTHWEST COUNTIES...BUT MAINTAINING THE WIND
ADVISORY OVERNIGHT WITH STRONG COLD ADVECTION AND A TIGHT WNW
PRESSURE GRADIENT MAINTAINING THROUGH THE NIGHT. THE PERSISTENT
LINGERING WRAP-AROUND STRATUS WILL KEEP MOST AREAS FROM REACHING
FREEZING BY TUESDAY MORNING. WNW WINDS 25-35 WITH GUSTS TO 40-45
WILL CONTINUE INTO THE EARLY MORNING HOURS TUESDAY.
05/
&&
.PREV DISCUSSION... /ISSUED 350 PM CST MON FEB 25 2013/
POWERFUL WINTER STORM CONTINUES TO MOVE THROUGH THE SOUTHERN
PLAINS THIS AFTERNOON RESULTING IN PRIMARILY A WIND EVENT ACROSS
NORTH TEXAS...BUT SOME WINTRY WEATHER IS EXPECTED THROUGH THIS
EVENING FOR PARTS OF THE AREA. LATEST SURFACE ANALYSIS SHOWS THE
CENTER OF THE SURFACE LOW NEAR EL DORADO ARKANSAS WHERE 3 HOUR
PRESSURE FALLS ARE IN EXCESS OF 7MB. PRESSURE FALLS EXTEND ALL THE
WAY WESTWARD TOWARD WICHITA FALLS WHERE A SURFACE TROUGH HAS
PERSISTED ALL DAY. THESE PERSISTENT PRESSURE FALLS ARE AN
INDICATION THAT THE ENTIRE UPPER STORM SYSTEM IS DEEPENING. WATER
VAPOR IMAGERY SHOWS A WELL DEFINED CIRCULATION WHICH APPEARS TO
NOW BE MOVING DUE EAST TOWARD THE BEST SURFACE PRESSURE FALLS.
THIS IS CONCERNING BECAUSE SUBSTANTIAL WRAP AROUND PRECIPITATION
DRIVEN BY FRONTOGENETICAL FORCING WILL LIKELY TRACK FARTHER SOUTH
THAN EARLIER ANTICIPATED. SHORT TERM HIGH RESOLUTION GUIDANCE
APPEARS TO HAVE SOMEWHAT OF A HANDLE ON THE MOVEMENT OF THE UPPER
SYSTEM BUT PRECIPITATION IS QUICKLY ERODED DUE TO STRONG
SUBSIDENCE. MESOSCALE FRONTOGENETICAL FORCING IS LIKELY TO WIN OUT
AT LEAST FOR A FEW HOURS ON THE BACK SIDE OF THE SYSTEM RESULTING
IN PRECIPITATION ACROSS MAINLY THE NORTHWEST COUNTIES THROUGH MIDNIGHT.
CONCERNING THE PRECIPITATION...FORECAST SOUNDINGS FROM BOTH THE
HIGH RES 3KM TTU WRF AND RAP MODEL SUGGEST THAT THE THERMAL
PROFILE WILL BE SUFFICIENTLY COLD FOR SNOWFALL PRODUCTION
GENERALLY NORTH OF INTERSTATE 20 THROUGH LATE TONIGHT...DESPITE
THE WARM SURFACE TEMPERATURES. INITIAL CONVECTIVE SHOWERS
NORTHEAST OF THE METROPLEX SHOULD REMAIN ALL LIQUID. GIVEN THE
POTENTIAL FOR SNOWFALL...ALONG WITH STRONG GUSTY WINDS...HAVE
ISSUED A SHORT DURATION WINTER WEATHER ADVISORY FOR THE FAR
NORTHWEST COUNTIES THROUGH MIDNIGHT. WITH WARM GROUND TEMPERATURES
AND GENERALLY ABOVE FREEZING SURFACE TEMPERATURES...EXPECT ANY
ACCUMULATIONS TO BE CONFINED TO GRASSY SURFACES. THE PRIMARY
CONCERN WILL BE FOR BLOWING SNOW WHICH COULD REDUCE VISIBILITY TO
LESS THAN 1/2 MILE AT TIMES. ROADS SHOULD REMAIN IN GOOD SHAPE.
THE OTHER MAIN CONCERN IS WINDS THROUGH LATE TONIGHT. WITH THE
CENTER OF THE SURFACE LOW NEARBY FOR MUCH OF THE AFTERNOON...WINDS
HAVE GENERALLY BEEN HIGHEST ACROSS THE SOUTHERN COUNTIES WHERE
GUSTS TO 54 MPH HAVE BEEN REPORTED. WITH THE SURFACE LOW NOW
MOVING EAST...THE PRESSURE GRADIENT WILL CONTINUE TO TIGHTEN
THROUGH EVENING. THE STRONGEST LOW LEVEL JET WILL BE CENTERED
ACROSS THE AREA RIGHT AROUND MIDNIGHT SO IT APPEARS THAT THE
STRONGEST WINDS ACROSS MUCH OF THE REGION ARE STILL TO COME.
ONE LIMITING FACTOR TO STRONGER WINDS WILL BE THE FACT THAT IT
WILL BE NIGHT WHEN THE STRONGEST WINDS ALOFT ARE OVERHEAD. THE CURRENT
WIND ADVISORY WILL REMAIN IN EFFECT THROUGH 4 AM FOR ALL OF NORTH
TEXAS.
WITH THE ENTIRE SYSTEM MOVING TO THE NORTHEAST TOMORROW...SKIES
SHOULD CLEAR AND WINDS WILL DIMINISH. A COUPLE OF REINFORCING
FRONTS...ONE ON WEDNESDAY AND ANOTHER LATE THURSDAY NIGHT...WILL
KEEP TEMPERATURES COOL THROUGH THE WEEK. NO SIGNIFICANT CHANGES TO
THE EXTENDED FORECAST AS IT APPEARS THAT IT WILL REMAIN DRY
THROUGH THE PERIOD.
DUNN
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 36 54 34 54 34 / 20 5 0 0 5
WACO, TX 37 61 34 60 33 / 5 0 0 0 5
PARIS, TX 36 49 31 51 31 / 30 5 0 0 5
DENTON, TX 36 53 30 51 31 / 30 5 0 0 5
MCKINNEY, TX 36 52 32 51 32 / 20 5 0 0 5
DALLAS, TX 37 56 35 55 35 / 20 5 0 0 5
TERRELL, TX 37 52 34 54 34 / 10 5 0 0 5
CORSICANA, TX 38 57 35 58 34 / 5 0 0 0 5
TEMPLE, TX 37 63 36 63 33 / 5 0 0 0 5
MINERAL WELLS, TX 34 57 30 54 29 / 30 0 0 0 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 4 AM CST TUESDAY FOR TXZ091>095-100>107-
115>123-129>135-141>148-156>162-174-175.
&&
$$
/
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1219 PM CST TUE FEB 26 2013
.UPDATE...
PRECIP WILL MOVE INTO THE CWA SHORTLY. RADAR TRENDS INDICATE THE
LEADING EDGE REACHING KENOSHA AIRPORT BETWEEN 1830Z AND 1900Z AND
MILWAUKEE AND JANESVILLE ABOUT AN HOUR TO AN HOUR AND A HALF
LATER. EROSION ON THE LEADING EDGE SLOWED THINGS DOWN A BIT
EARLIER TODAY AND BIT MORE EROSION IS POSSIBLE AS IT HEADS INTO
DRY AIR. SO FAR THE HRRR HAS BEEN PRETTY ACCURATE WITH THE LEADING
EDGE...MAYBE A BIT SLOW.
EXPECTING A MIX OF RAIN...SLEET...AND SNOW AT FIRST IN THE FAR
SOUTHEAST. THINKING THE PRECIP WILL CHANGE OVER TO SNOW RELATIVELY
QUICKLY...WITHIN A HOUR OR TWO...AS THE LOW AND MID LEVELS
SATURATE. THINKING WE WILL SEE MODERATE TO HEAVY SNOW AS SOON AS
SNOW BEGINS.
ADDED IOWA AND DANE COUNTIES TO THE ADVISORY AS THE SOUTHERN
PORTIONS OF THE COUNTIES COULD CERTAINLY REACH THE 3 TO 5 INCH
MARK. ALSO EXTENDED THE ADVISORY ACROSS THE BOARD TO NOON
TOMORROW. SNOW IS EXPECTED TO CONTINUE INTO WEDNESDAY MORNING AND
WILL BECOME MORE DRY WITH TIME...ALLOWING FOR MORE BLOWING AND
DRIFTING.
&&
.AVIATION/18Z TAFS/...
EXPECTING CONDITIONS TO DETERIORATE QUICKLY AS PRECIP MOVES IN.
LOOKS LIKE PRECIP WILL BEGIN NO LATER THAN 19Z AT ENW AND AROUND
20Z AT MKE. EXPECTING TO SEE A MIX OF RAIN AND SNOW AND POSSIBLY
SLEET AT MKE AND ENW. DON/T EXPECT THIS TO LAST LONG AS AIR AND
LOWER AND MID LEVELS SATURATES. THINKING UES WILL ONLY GET
SNOW...BUT A VERY BRIEF MIX IS POSSIBLE. MSN WILL LIKELY ONLY SEE
SNOW.
18Z OBS SHOW FEW/SCT LOW CLOUDS ALREADY MOVING IN AT MSN
AND UES...A BIT EARLIER THAN EXPECTED. GENERALLY EXPECTING LOW
CLOUDS TO QUICKLY DEVELOP AS PRECIP MOVES IN AND THINGS SATURATE.
CONCERNED THAT CEILINGS COULD BE EVEN LOWER LOOKING AT THE LATEST
NORTHERN ILLINOIS OBS...IN THE BELOW ALTERNATE MINIMUMS RANGE.
ALSO...COULD SEE MODERATE OR EVEN HEAVY SNOW AS SOON AS SNOW
BEGINS. VISIBILITIES COULD EASILY REACH THE BELOW ALTERNATE
MINIMUMS RANGE.
EXPECTING IFR TO BELOW ALTERNATE MINIMUM VISIBILITIES AND/OR
CEILINGS TO PERSIST THROUGH THE DAY WEDNESDAY AS THE LOW PRESSURE
LINGERS OVER THE EASTERN GREAT LAKES REGION.
&&
.MARINE...
A GALE WARNING REMAINS IN EFFECT THROUGH WEDNESDAY NIGHT AS
STRONG LOW PRESSURE TRACKS FROM NORTHEAST ARKANSAS TO LOWER
MICHIGAN BY WEDNESDAY MORNING. BRISK EAST TO NORTHEAST WINDS WILL
GUST TO GALE FORCE AND THEN TURN NORTHERLY ON WEDNESDAY. HIGH
WAVES ARE EXPECTED.
&&
.PREV DISCUSSION... /ISSUED 329 AM CST TUE FEB 26 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.
MODERATE 250 MB UPPER LEVEL DIVERGENCE LIFTS NORTH FROM ILLINOIS
EARLY THIS MORNING. THIS SEEN BY RAPIDLY THICKENING CLOUDS. THIS
UPPER LEVEL DIVERGENCE CONTINUES THROUGH THE NIGHT...AS IT
WEAKENS.
GOOD MID LEVEL WARM TROWAL LIFTS NORTH ACROSS SOUTHERN WISCONSIN
TODAY. STRONG 700 MB UPWARD MOTION LIFTS NORTH BUT WEAKENS AS IT
REACHES SOUTHERN WISCONSIN. HOWEVER THIS LIFT CONTINUES THROUGH
THE NIGHT.
MODERATE 850 MB MOISTURE CONVERGENCE THIS AFTERNOON BEFORE
WEAKENING A LITTLE. NEVER THE LESS MODELS AGREE ON PUSHING
PRECIPITATION NORTHWARD INTO FAR SOUTHERN WISCONSIN THIS
AFTERNOON, THEN ACROSS MUCH OF THE FORECAST AREA TONIGHT. MAIN
FORECAST CONCERN IS WITH AMOUNTS. MOST MODELS HAVE TRENDED TOWARD
THE HIGHER NAM...ALTHOUGH IT IS STILL HIGHER NEAR LAKE MICHIGAN
THAN THE REST. IT APPEARS THE CONSENSUS PRECIPITATION IS VERY
REASONABLE, GIVEN THE GFS MAY BE TOO LOW.
STRONG AND GUSTY NORTHEAST WINDS ARE EXPECTED AS THE LOW PRESSURE
APPROACHES NORTHERN INDIANA AND SOUTHERN LOWER MICHIGAN.
THE EASTERLY WINDS WILL KEEP LOW LEVEL DRY AIR IN PLACE OVER
SOUTHERN WI...WHICH WILL LEAD TO A DELAY IN PRECIP ON THE NORTH
SIDE OF THE LOW MAKING IT INTO SOUTHERN WI. HOWEVER THIS WILL ALSO
AID IN EVAPORATIVE COOLING WHICH COMBINED WITH DYNAMIC COOLING
SHOULD RESULT IN A SNOW EVENT...WITH A POSSIBLE RAIN/SNOW MIXTURE
AT ONSET.
WILL PUSH SNOW AMOUNTS TO NEAR WINTER STORM WARNING CRITERIA IN
THE FAR SOUTHEAST...INCLUDING MILWAUKEE TO KENOSHA. IF THE HIGHER
PRECIP TRENDS CONTINUE ON LATER MODEL RUNS A WARNING MAY BE
NEEDED...GIVEN THE STRONG WINDS AND WET HEAVY SNOW.
WEDNESDAY THROUGH THURSDAY NIGHT...FORECAST CONFIDENCE IS HIGH.
SHORT TERM MODELS ARE IN DECENT AGREEMENT WITH TAKING SURFACE LOW
FROM FAR NORTHEAST INDIANA/FAR NORTHWEST OHIO SLOWLY EASTWARD
WEDNESDAY AND WEDNESDAY NIGHT...REACHING NEW ENGLAND BY 12Z
THURSDAY. ASSOCIATED 500MB LOW SHIFTS SLOWLY EASTWARD IN A SIMILAR
FASHION...BEING NEARLY VERTICALLY STACKED WITH THE SURFACE LOW.
VARIOUS VORTICITY MAXIMA AT 500MB ROTATE CYCLONICALLY THROUGH THE
AREA WEDNESDAY INTO WEDNESDAY NIGHT. LITTLE IF ANY LOW TO MID
LEVEL FRONTOGENESIS RESPONSE DURING THIS TIME...WITH WEAK Q VECTOR
CONVERGENCE IN THE LOW LEVELS.
AREA FORECAST SOUNDINGS FROM NAM/GFS SHOWING WEAK UPWARD VERTICAL
MOTION DURING THIS TIME...BUT AIR COLUMN IS SATURATED IN THE LOW
TO MID LEVELS FOR MOST OF WEDNESDAY INTO WEDNESDAY
EVENING...BEFORE DRYING OUT FROM THE TOP DOWN LATER WEDNESDAY
NIGHT. WINDS REMAIN GUSTY OUT OF THE NORTH WEDNESDAY WITHIN TIGHT
PRESSURE GRADIENT. GUSTS OF 30 KNOTS PLUS APPEAR POSSIBLE ON AREA
FORECAST SOUNDINGS...ESPECIALLY IN THE NORTHEAST HALF OF THE
AREA...AND NEAR THE LAKE. THIS MAY LEAD TO SOME BLOWING SNOW.
WINDS REMAIN SOMEWHAT GUSTY WEDNESDAY NIGHT.
SHORT TERM MODELS CONTINUE TO SHOW QPF OF GENERALLY 0.08 TO 0.15
INCHES WEDNESDAY...WITH A FEW HUNDREDTHS MORE WEDNESDAY NIGHT.
SNOW TO LIQUID RATIOS WILL BE LOW WEDNESDAY WITH HIGHS AROUND OR
JUST ABOVE FREEZING...WHICH SHOULD KEEP SNOW ACCUMULATIONS AT AN
INCH OR LESS. CIPS ANALOGS DO SHOW 1 TO 2 INCHES POSSIBLE
WEDNESDAY. RAISED POPS TO CATEGORICAL FOR WEDNESDAY...WITH LOWER
POPS WEDNESDAY NIGHT.
THURSDAY AND THURSDAY NIGHT THEN HAVE A WEAK 500MB RIDGE MOVING
INTO THE REGION ON THE SHORT TERM MODELS. AT THE SURFACE...AREA
REMAINS BETWEEN LOW PRESSURE WELL EAST OF THE REGION...AND HIGH
PRESSURE WELL NORTH OF THE REGION. PRESSURE GRADIENT DOES RELAX
DURING THIS TIME...SO WINDS SHOULD DECREASE IN MAGNITUDE. AREA
FORECAST SOUNDINGS FROM NAM/GFS DRY OUT EXCEPT BELOW LOW LEVEL
INVERSION AROUND 3000 FEET ABOVE GROUND LEVEL. THUS...QPF FROM
GFS/CANADIAN SEEMS OVERDONE VERSUS DRY NAM/ECMWF. WENT DRY FOR
THURSDAY.
HOWEVER...LAKE EFFECT SNOW POTENTIAL INCREASES THURSDAY
NIGHT...AS LOW LEVEL WINDS REMAIN NORTHEAST AND DELTA T VALUES
INCREASE TO 12 TO 13 DEGREES CELSIUS. THIS IS BORDERLINE FOR LAKE
EFFECT SNOW. STILL...LOW LEVELS REMAIN MOIST BELOW INVERSION AND
TAP SHALLOW DENDRITE GROWTH ZONE. LAKE EFFECT SNOW FLOW CHART ONLY
SHOWS MINOR ACCUMULATIONS UP TO AN INCH. WILL KEEP POPS FOR
THURSDAY NIGHT NEAR THE LAKE. CIPS ANALOGS SHOW LIGHT
ACCUMULATIONS THURSDAY NIGHT. TEMPERATURES WILL REMAIN NEAR OR
JUST ABOVE SEASONAL NORMALS.
FRIDAY THROUGH MONDAY...FORECAST CONFIDENCE IS MEDIUM.
GFS/ECMWF IN GENERAL AGREEMENT WITH FEATURES THROUGH MOST OF THE
WEEKEND...WITH DIFFERENCES FOR SUNDAY NIGHT/MONDAY. GFS MAINTAINS
LAKE EFFECT SNOW POTENTIAL FRIDAY INTO SATURDAY NIGHT NEAR THE
LAKE. FORECAST SOUNDINGS SHOW DELTA T VALUES REMAINING AROUND 13
DEGREES CELSIUS WITH NORTHEAST LOW LEVEL FLOW. POPS MAY BE NEEDED
NEAR THE LAKE IN LATER FORECASTS. THE ECMWF IS SHOWING LIGHT QPF
NEAR THE SHORE AS WELL DURING PARTS OF THIS PERIOD.
THE REST OF THE AREA WILL SEE QUIET WEATHER WITH A HIGH PRESSURE
RIDGE MOVING INTO THE REGION. DRY AIRMASS WILL LIMIT EFFECT OF
PASSING 500MB SHORTWAVE TROUGH. TEMPERATURES SHOULD REMAIN NEAR OR
JUST BELOW SEASONAL NORMALS.
GFS THEN BRINGS LOW PRESSURE FROM SOUTH DAKOTA INTO NORTHWEST
IOWA SUNDAY NIGHT AND MONDAY...SPREADING QPF WITHIN WARM AIR
ADVECTION/FRONTOGENESIS OVER THE REGION. ECMWF KEEPS THIS FEATURE
FURTHER TO THE WEST DURING THIS TIME...AND HAS THE AREA DRY. GIVEN
THE DIFFERENCES...WILL USE CONSENSUS POPS AND TEMPERATURES FOR
SUNDAY NIGHT AND MONDAY.
AVIATION/12Z TAFS/...
CEILINGS WILL CONTINUE TO LOWER TODAY WITH MAINLY VFR CONDITIONS
INTO THE EARLY AFTERNOON. THEN WITH PRECIPITATION SPREADING NORTH
MVFR CONDITIONS WILL LOWER TO IFR AND SOME LIFR AS STRONG LOW
PRESSURE MOVES INTO NORTHERN INDIANA LATE TONIGHT.
EAST WINDS WILL INCREASE THIS MORNING. WINDS WILL QUITE STRONG OUT
OF THE NORTHEAST ON LATER TODAY AND TONIGHT.
MARINE...
A GALE WARNING IS IN EFFECT THROUGH WEDNESDAY NIGHT AS STRONG LOW
PRESSURE TRACKS FROM NORTHEAST ARKANSAS TO LOWER MICHIGAN BY
WEDNESDAY MORNING. BRISK EAST TO NORTHEAST WINDS WILL GUST TO GALE
FORCE AND THEN TURN NORTHERLY ON WEDNESDAY. HIGH WAVES ARE
EXPECTED.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON CST
WEDNESDAY FOR WIZ062>072.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON CST
WEDNESDAY FOR WIZ052-059-060.
LM...GALE WARNING UNTIL 4 AM CST THURSDAY FOR LMZ643>646.
&&
$$
UPDATE...MEB
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
WEDNESDAY THROUGH MONDAY...WOOD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1156 AM CST TUE FEB 26 2013
.SHORT TERM...THIS AFTERNOON THROUGH WEDNESDAY
1154 AM CST TUE FEB 26 2013
THE 26.12Z MODELS CONTINUED THE TREND OF THE 26.06Z MODELS AND
SHIFTED THE DEFORMATION SNOW BAND A BIT FURTHER NORTH INTO
SOUTHWEST WISCONSIN AND NORTHEAST IOWA. THE GFS CONTINUED TO BE
THE FURTHEST NORTH. MEANWHILE THE 26.06Z ARW AND NMM...AND THE
26.12Z RAP...NAM...GEM...AND HRRR SHOW THAT THIS BAND WILL A BIT
FURTHER SOUTH. OVERALL...THINK THAT THE GFS IS A BIT TOO FAR
NORTH...SO TRENDED THE FORECAST TOWARD THE OTHER MODEL RUNS.
OVERALL THE QPF LOOKS TO BE IN THE 0.25 TO 0.50 INCH RANGE SOUTH
OF A RICHLAND CENTER TO OELWEIN IOWA LINE FROM MID-AFTERNOON TODAY
THROUGH WEDNESDAY MORNING. COBB DATA WOULD SUGGEST RATIOS RANGING FROM
10-15 TO 1. THIS WOULD RESULT IN 3 TO 6 INCH SNOW TOTALS FOR THE
SOUTHERN AND EASTERN PORTIONS OF BOTH FAYETTE AND CLAYTON COUNTIES
IN NORTHEAST IOWA...AND GRANT COUNTY IN SOUTHWEST WISCONSIN.
IN ADDITION TO THE SNOW...NORTH WINDS AT 10 TO 20 MPH MAY CAUSE
AREAS OF BLOWING AND DRIFTING SNOW ACROSS THESE AREAS FROM TONIGHT
IN WEDNESDAY MORNING.
DUE TO THIS SNOW AND BLOWING SNOW...WENT WITH A WINTER WEATHER
ADVISORY FROM 3 PM THIS AFTERNOON THROUGH 12 PM WEDNESDAY FOR
FAYETTE AND CLAYTON COUNTIES IN NORTHEAST IOWA...AND GRANT COUNTY
IN SOUTHWEST WISCONSIN.
LIGHT SNOW MAY CONTINUE INTO WEDNESDAY AFTERNOON...BUT ADDITIONAL
ACCUMULATIONS WILL BE LESS THAN AN INCH.
.LONG TERM...FRIDAY THROUGH MONDAY
325 AM CST TUE FEB 26 2013
25.00Z MEDIUM RANGE MODELS IN RATHER GOOD AGREEMENT WITH EACH OTHER
AND THEIR PREVIOUS RUNS FRI INTO SUNDAY. THIS WITH TROUGHING OVER
EASTERN NOAM AND RIDGING OVER WESTERN NOAM...AND THE THE UPPER
MIDWEST IN BETWEEN UNDER NORTHWEST TO NORTH FLOW ALOFT. FRI-SUN
CONTINUES TO TREND DRY. TEMPS COOLER FOR FRI/SAT UNDER NORTHERLY
FLOW AND COOLER 925-850MB TEMPS ALOFT. QUESTIONS ARISE AS TO HOW
QUICKLY SOME LOW LEVEL WARM ADVECTION RETURNS FOR SUN...WITH GFS
FASTER/MORE ROBUST THAN ECMWF/GEM. BY MON MODELS DIFFER ON THE
STRENGTH/TRACK OF THE NEXT STRONGER SHORTWAVE/SFC LOW AFTER IT
CROSSES THE NORTHERN ROCKIES INTO THE NORTHERN PLAINS. LITTLE
BETWEEN MODEL AND RUN-TO-RUN CONSISTENCY ON THIS DAY 7 FEATURE...
WHICH IS NOT UNEXPECTED WITH THE PATTERN LOOKING TO BREAK DOWN THE
WESTERN NOAM RIDGE INTO EARLY NEXT WEEK. FOR NOW A SMALL -SN
CHANCE WITH SEASONABLE TEMPS PER THE MODEL/ENSEMBLE CONSENSUS LOOKS
REASONABLE ON MONDAY. THE MODEL/ENSEMBLE CONSENSUS DATA SET ALSO
LOOKS TO HAVE DAYS 4-6 WELL TRENDED AT THIS TIME.
&&
.AVIATION...THROUGH 18Z WEDNESDAY
1154 AM CST TUE FEB 26 2013
A DEFORMATION BAND OF SNOW WILL BE SEEN ACROSS SOUTHWEST WISCONSIN
AND NORTHEAST IOWA FROM THIS AFTERNOON THROUGH WEDNESDAY MORNING.
THIS SNOW WILL RDUCE VISIBILITIES TO LESS THAN A MILE.
BOTH THE TAF SITES WILL BE ON THE NORTHERN EDGE OF THIS SNOW BAND.
AT KLSE...THE GFS QUICKLY SATURATES THE SOUNDING BY 27.06Z.
MEANWHILE THE NAM DOES NOT SHOW THIS OCCURRING UNTIL 27.12Z. THE
RAP WAS A GOOD COMPROMISE BETWEEN THESE TWO...SO WENT WITH THAT
AND HAVE THE SNOW DEVELOPING BETWEEN 27.07Z AND 27.09Z. THIS SNOW
WILL REDUCE THE VISIBILITIES TO 2 MILES AND CEILINGS TO MVFR.
AT KRST...IT LOOKS LIKE DRY AIR BELOW 10K FEET WILL KEEP THIS TAF
SITE DRY...THUS...KEPT THIS SITE WITH VFR CEILINGS AND VISIBILITIES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
1137 AM CST TUE FEB 26 2013
WI...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON CST
WEDNESDAY FOR WIZ061.
MN...NONE.
IA...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON CST
WEDNESDAY FOR IAZ029-030.
&&
$$
SHORT TERM...BOYNE
LONG TERM....RRS
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
317 AM EST THU FEB 28 2013
.SYNOPSIS...
LOW PRESSURE WILL DRIFT EAST FROM THE GREAT LAKES TO NEW ENGLAND
THROUGH THE END OF THE WEEK. AN UPPER LEVEL TROUGH WILL THEN
PERSIST OVER THE EASTERN STATES THROUGH THE WEEKEND. HIGH PRESSURE
IS EXPECTED EARLY NEXT WEEK. LOW PRESSURE LOOKS TO APPROACH THE
MID-ATLANTIC AROUND THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
WITH A LARGE UPPER CLOSED LOW HANGING OVER THE GREAT LAKES AND UPPER
MIDWEST...CONTINUED WAVES OF CLOUDS AND PERIODIC SHOWERS WILL SLIDE
OVER THE REGION. THE WARM SIDE OF THE SYSTEM MOVED ACROSS THE REGION
ON TUE...BUT IS NOW WELL NORTH AND EAST OF THE AREA. AT THIS
POINT...THE MID ATLC IS ON THE SOUTHEASTERN QUADRANT OF THIS LARGE
ENCOMPASSING UPPER FEATURE. MUCH SMALLER-SCALE WAVES OF WEAK LIFT
AND MOISTURE CONVERGENCE HAVE BEEN AND WILL CONTINUE TO GENERATE
LIGHT SHOWERS ACROSS THE LOWLANDS AND MINOR ACCUMULATIONS OF UPSLOPE
SNOW SHOWERS FOR THE MTNS. SAME STORY AT THE MOMENT...W/ BATCHES OF
LIGHT RAIN DEVELOPING OVER THE VA/MD PIEDMONT SINCE MIDNIGHT. SOME
LIGHT SHOWERS WILL AFFECT THE DC/BALT AREAS AND BACK TOWARD THE BLUE
RIDGE...SLOWLY DRIFTING TOWARD THE EAST THRU DAWN.
NEAR TERM GUIDANCE...ESPEC THE HRRR WHICH RECENT RUNS APTLY DEPICTED
THE CURRENT ACTIVITY...SHOW ANOTHER BATCH OF MOISTURE CONVERGENCE
ACROSS THE I-95 CORRIDOR LATER THIS MRNG - TOWARD EARLY AFTN. THIS
WOULD LEAVE A DRY MORNING FROM AROUND DAWN THRU AROUND NOON BEFORE
THE NEXT BATCH OF SCATTERED SHOWERS DEVELOPS. RELATIVELY MILD
OVERNIGHT LOWS IN THE U30S-L40S WILL GRADUALLY RISE TOWARD THE U40S
TO AROUND 50 BY MID AFTN. WLY WINDS WILL AGAIN PICK UP IN THE
AFTN...ONLY CUTTING DOWN THE APPARENT TEMPS BY A FEW DEGREES BUT NOT
PARTICULARLY WINDY - MAINLY A 15-20MPH BREEZE.
BACKING OUT TO A LARGER VIEW AGAIN - THE PARENT UPPER LOW WILL BE
MAKING A SLOW/STEADY WOBBLE TOWARD THE SE OVER THE COURSE OF TODAY
AND INTO TONIGHT FROM UPSTATE NY. ONE OF THE MORE POTENT UPPER VORT
MAXES ASSOCIATED W/ THIS FEATURE WILL BE SWINGING DOWN AROUND THE
BACKSIDE OF THE LOW - DIRECTLY OVER THE REGION LATER TONIGHT. A
BRIEF PERIOD OF GUSTY NW WINDS WILL MOVE OVER THE AREA OVERNIGHT AND
HELP PUSH THE EARLIER PRECIP WELL OFF THE COAST AND DRY OUT THE
REGION HEADING INTO FRI.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
A CUTOFF LOW WILL REMAIN OVER NEW ENGLAND FRIDAY THROUGH FRIDAY
NIGHT WHILE THE UPPER-LEVEL TROUGH ASSOCIATED WITH THIS SYSTEM
REMAINS OVERHEAD.
A NORTHWEST FLOW BETWEEN SURFACE LOW PRESSURE NEAR THE CANADIAN
MARITIMES AND HIGH PRESSURE OVER THE CENTRAL CONUS WILL ALLOW FOR
CHILLY CONDITIONS. MAX TEMPS FRIDAY WILL RANGE FROM THE 20S IN
PORTIONS OF THE ALLEGHENY HIGHLANDS TO THE MIDDLE AND UPPER 40S NEAR
WASHINGTON AND BALTIMORE. MIN TEMPS FRIDAY NIGHT WILL RANGE FROM THE
TEENS IN THE ALLEGHENY HIGHLANDS TO THE LOWER AND MIDDLE 30S IN
DOWNTOWN WASHINGTON/BALTIMORE.
A BKN STRATO CU WILL CAUSE PARTLY TO MOSTLY CLOUDY SKIES. DRIER AIR
ASSOCIATED WITH THE NORTHWEST FLOW WILL KEEP DRY CONDITIONS ACROSS
THE REGION FOR MOST OF THE TIME. HOWEVER...A FEW SPRINKLES AND
FLURRIES ARE POSSIBLE FRIDAY AFTERNOON DUE TO LIMITED INSTABILITY
ASSOCIATED WITH DAYTIME HEATING.
FOR LOCATIONS ALONG AND WEST OF THE ALLEGHENY FRONT. AN UPSLOPE
COMPONENT TO THE LOW-LEVEL FLOW WILL LIKELY TRIGGER SNOW SHOWERS.
ACCUMULATIONS DURING THE DAY FRIDAY SHOULD BE LIGHT. SNOW SHOWERS
ARE POSSIBLE FRIDAY NIGHT...BUT ANY ACCUMULATION WILL BE LIGHT.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
UPR TROUGH AXIS DRIFTS EAST ACROSS THE MID-ATLANTIC SATURDAY THROUGH
SUNDAY WITH SFC PRESSURE BUILDING FROM THE WEST BEHIND THE AXIS.
BELOW NORMAL TEMPERATURES EXPECTED UNDER THE CANADIAN SOURCED
AIR...THOUGH ONLY 5 TO 10 DEGREES BELOW. MAX TEMPS LOW TO MID 40S
SATURDAY...THEN UPR 30S TO LOW 40S SUNDAY. DRY.
THE NEXT LOW LOOKS TO TRACK ACROSS THE MID-SOUTH STATES EARLY NEXT
WEEK AND IMPACT THE MID-ATLANTIC IN THE MIDDLE OF THE WEEK. WAY TOO
EARLY TO TAKE AN OPERATIONAL RUN VERBATIM /AKA THE 00Z ECMWF/...SO
WILL SIMPLY HAVE TO MONITOR THE POTENTIAL FOR LATE SEASON SNOW AS
THE DAYS PROGRESS.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
PLENTY OF CLOUD COVER OVERNIGHT AND THRU THE DAY TODAY. A FEW
SHOWERS WILL DRIFT OVER THE DC/BALT AREA THRU AROUND 12Z BUT THEN
DRY OUT FOR A FEW HRS. ANOTHER ROUND OF LIGHT SHOWERS EXPECTED
TOWARD THE EARLY AFTN HRS...LAST FOR A FEW HRS THEN ALSO DISSIPATE
AND EXIT TO THE EAST. A FEW NEAR 20KT GUSTS WILL AFFECT THE WRN HALF
OF THE AREA THIS AFTN...INCLUDING THE FOOTHILLS OF THE BLUE RIDGE
TOWARD KCHO AND KIAD. A GENERAL W-NW WIND WILL CONTINUE THRU THE
CURRENT TAF CYCLE.
VFR CONDITIONS ARE EXPECTED MOST OF THE TIME FRIDAY THROUGH THE
WEEKEND. HOWEVER...A BKN STRATOCU DECK MAY APPROACH 3KFT AT TIMES.
NORTHWEST WINDS ARE EXPECTED THROUGH THE PERIOD WITH GUSTS AROUND 15
TO 25 KNOTS.
&&
.MARINE...
LIGHT WINDS OVER THE WATERS...THOUGH SOME MARGINAL SCA GUSTS MAY
APPEAR DURING THE DAYTIME HRS TODAY. A GENERAL 10-15KT WLY BREEZE
WILL BE STEADY...BUT THE HIGHER GUSTS SHOULD HOLD OFF UNTIL
OVERNIGHT AND INTO EARLY FRI MRNG.
A NORTHWEST FLOW BETWEEN LOW PRESSURE NEAR THE CANADIAN MARITIMES
AND HIGH PRESSURE OVER THE CENTRAL CONUS WILL CONTINUE FRIDAY
THROUGH THE WEEKEND. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE
WATERS FRIDAY AND THE SMALL CRAFT ADVISORY MAY NEED TO BE EXTENDED
INTO SATURDAY FOR PORTIONS OF THE WATERS.
HIGH PRESSURE WILL BUILD TOWARD THE WATERS EARLY NEXT WEEK.
&&
.TIDES/COASTAL FLOODING...
MOST OF THE BAY/TP SITES EITHER IN LOW TIDE OR HEADING OUT OF THE
OVERNIGHT LOW TIDE CYCLES. POSITIVE ANOMALIES HAVE NOT RECEDED TO A
LARGE DEGREE...IN FACT - MOST SITES ARE STILL AROUND OR JUST BELOW
ONE FT ABOVE AVG. THIS WILL KEEP AN ELEVATED RISK OF NEAR-MINOR
THRESHOLDS HEADING INTO THE NEXT HIGH TIDE CYCLE. NO SINGLE FORECAST
POINT HAS CRITERIA BEING REACHED...THOUGH MOST ARE FAIRLY CLOSE.
WILL CONTINUE TO MONITOR THESE TRENDS BUT LEVELS SHOULD CONTINUE TO
DROP ALBEIT SLOWLY - FROM CONTINUED W-NWLY WINDS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST FRIDAY FOR ANZ530-
531-535-536-538-539.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST
FRIDAY FOR ANZ532>534-537-540>543.
&&
$$
SYNOPSIS...BAJ
NEAR TERM...GMS
SHORT TERM...BJL
LONG TERM...BAJ
AVIATION...BJL/GMS
MARINE...BJL/GMS
TIDES/COASTAL FLOODING...GMS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1240 AM EST THU FEB 28 2013
.SYNOPSIS...
AN UPPER LEVEL LOW WILL MOVE ACROSS THE AREA OVERNIGHT AND PUSH
INTO THE NORTHEAST FOR THE END OF THE WEEK. AS THE LOW SHIFTS EAST
OF THE REGION...COLDER AIR WILL FILTER INTO THE AREA TONIGHT AND
AND PROVIDE SNOW SHOWERS INTO FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
UPDATE TO REDUCE POPS A BIT OVERNIGHT AS RADAR COVERAGE OF SNOW
SHOWERS HAS DIMINISHED. THE LATEST RAP MID-LEVEL ANALYSIS
INDICATES A RATHER ELONGATED CLOSED UPPER LOW THAT STRETCHES
ACROSS THE SOUTHERN GREAT LAKES AND OHIO VALLEY. AT THE
SURFACE...A 999MB LOW IS CENTERED ACROSS SOUTHERN MICHIGAN WITH
ANOTHER LOW DEVELOPING AS IT MOVES NORTHWARD ACROSS NEW JERSEY.
THE LOW IN MICHIGAN IS DRIVING A SOUTHWESTERLY FLOW ACROSS THE
AREA TODAY. SOUNDINGS INDICATE A SFC-900MB MELTING LAYER STRONG
ENOUGH TO ALLOW FOR PRECIP SOUTH AND WEST OF PITTSBURGH TO BE ALL
RAIN. 1000-700MB 2840M THICKNESS LINE ALSO SEEMS TO COINCIDE
FAIRLY WELL WITH RAIN/SNOW LINE NORTHEAST OF PITTSBURGH.
THIS EVENING...THE BROAD UPPER LOW WILL SLOWLY MEANDER EASTWARD
ACROSS THE OHIO VALLEY...WITH THE NEXT VORT LOBE SWINGING AROUND
ITS BASE. WRF-ARW 1KM SIMULATED REFLECTIVITY DEPICTS MORE
CONVECTIVE SHOWERS EARLY THIS EVENING...SO HAVE GONE WITH
ISOLATED/SCATTERED INCREASING TO MORE NUMEROUS AS THE UPPER LOW
APPROACHES FROM THE WEST. DESPITE COLDER AIR ADVECTING IN WITH
THE COLD POOL ALOFT AND ASSOCIATED UPPER LOW...GFS/NAM SOUNDINGS
CONTINUE TO INDICATE PRECIPITATION WILL FALL INITIALLY AS RAIN
WITH A SUFFICIENT SFC-900MB MELTING LAYER REMAINING IN PLACE.
THUS...FORECAST BEINGS WITH MOSTLY RAIN...EXCEPT FOR SOME RAIN-SNOW
CLOSER TO 1000-700MB CRITICAL THICKNESS ACROSS THE NORTH AND WITH
THE LACK OF A PRONOUNCED MELTING LAYER ACROSS THE RIDGES.
OVERNIGHT...GFS/NAM AGREE THAT THE UPPER LOW WILL CROSS THE AREA AS
IT SHIFTS FROM WESTERN OHIO INTO WESTERN NY. WEAK CAA AND COOLING
SFC-900MB LAYER WILL ALLOW FOR ENTIRE COLUMN TO DROP BELOW
FREEZING AND PRECIPITATION TO CHANGE OVER TO ALL SNOW SHOWERS
TONIGHT. ACCUMULATIONS WILL BE AN INCH OR LESS FOR SOUTHWEST
PA...EASTERN OHIO...AND NORTHERN WV WITH 1 TO 2 INCHES POSSIBLE
TONIGHT ACROSS THE ALLEGHENY FRONT/LAUREL HIGHLANDS AND I-80
CORRIDOR. TEMPS TONIGHT ARE FAIRLY CLOSE TO A MAV/MET BLEND...WITH
LOWS RANGING FROM THE MID 20S ACROSS THE EASTERN RIDGES TO THE
LOWER 30S ELSEWHERE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
A MODEL CONSENSUS INDICATES THAT THE UPPER LOW WILL SLOWLY MEANDER
EASTWARD INTO NEW ENGLAND THURSDAY AND FRIDAY...LEAVING THE UPPER
OHIO VALLEY IN A MOIST...NORTHWESTERLY FLOW OFF OF THE GREAT
LAKES.
THE LOW-LEVEL FLOW WILL BE CLOSE TO ZONAL MUCH OF THE DAY THURSDAY
AS A SERIES OF VORT LOBES ROTATES AROUND THE UPPER LOW AND INTO
THE AREA. WITH SFC TEMPS WARMING TO THE MID TO UPPER 30S ACROSS
THE LOWLANDS...ANTICIPATE LITTLE ACCUMULATION DURING DAYLIGHT
HOURS ACROSS THE LOWLANDS. WITH SOME UPSLOPING AND TEMPS IN THE
LOWER 30S...1 TO 2 INCHES WILL BE POSSIBLE ACROSS THE HIGHER
ELEVATIONS.
VORT ENERGY WILL SLIDE EAST OF THE UPPER OHIO VALLEY THURSDAY
NIGHT INTO FRIDAY. DURING THIS TIME...THE LOW-LEVEL FLOW WILL
VEER TO MORE NORTH-NORTHWESTERLY...ALLOWING FOR A MOISTURE FETCH
OFF OF LAKE HURON WITH MOISTURE LACKING FROM A PARTIALLY FROZEN
LAKE ERIE. ONE LIMITING FACTOR DESPITE THE NNWRLY FLOW WILL BE
THAT THE AIR MASS WILL NOT BE QUITE COLD ENOUGH TO SUPPORT LAKE
EFFECT. THUS...ANTICIPATE LITTLE MORE THAN SCATTERED SNOW SHOWERS
THROUGH THIS PERIOD WITH AROUND AN INCH FOR THE LOWLANDS AND AN
ADDITIONAL 1 TO 2 FOR THE RIDGES. TEMPS THROUGH THIS PERIOD WILL
BE AROUND 5 DEGREES BELOW NORMAL WITH THE NORTHERLY COMPONENT
CONTINUING TO PULL COOLER...CANADIAN AIR INTO THE AREA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
ECMWF AND GFS INDICATE CONTD MAINTENANCE OF THE ERN NORTH
AMERICAN TROF VIA SHRTWV ENERGY THRU THE LONG TERM PD. THE
EXTENDED FORECAST THUS CONTINUES TO FEATURE SUB AVERAGE TEMPS AND
NR CLIMO/CHC POPS UNTIL THE TROF AXIS SHIFT SUFFICIENTLY
EWD...PROBABLY BY SATURDAY.
SHRTWV RIDGE IN ADVN OF MIDWRN LOW IS CURRENTLY PROGGED TO
SUPPRESS PRECIP PROBABILITIES...UNTIL THE LOW INITIATES PCPN LTR
ON TUE. CONFIDENCE IN THAT PORTION OF THE FORECAST IS MINIMAL
GIVEN PROJECTIONS OF A CUTOFF SYSTEM WITH QUESTIONS OF MAGNITUDE
AND PLACEMENT OF THE LOW CENTERS.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
GENERAL MVFR CIG FORECAST THROUGH THE PERIOD. PERIODS OF IFR CIGS
ARE POSSIBLE...PARTICULARLY DURING MORE PROBABLE TIMES OF -SN.
FOLLOWING TWO SHORTWAVES WHICH WILL BRING A HIGHER RISK OF SNOW
SHOWER ACTIVITY AND POSSIBLY LOWER CLOUDS. FIRST WILL MOVE ACROSS
OHIO DURING THE PREDAWN HOURS...THE SECOND WILL MOVE SOUTHWARD
THROUGH THE ENTIRE REGION THIS AFTERNOON. THE SECOND WAVE WILL BE
PUSHING A SFC FRONT SOUTHWARD. THE AFTERNOON WAVE WILL BRING A
HIGHER PROBABILITY OF WIDESPREAD SNOW SHOWERS AND THUS LOWER
RESTRICTIONS.
SOUTHWEST WINDS THIS MORNING WILL VEER TO WEST THIS AFTERNOON.
SPEEDS WILL GENERALLY BE BETWEEN 10 AND 15KTS.
.OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/...
MAINLY CIGS RESTRICTIONS ARE LIKELY INTO SUNDAY AS LOW PRES CONTINUES
TO DRIFT EWD. VFR CONDS EXPD TO RETURN MON AS HI PRES BLDS IN.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
215 AM EST THU FEB 28 2013
.UPDATE...
ISSUED AT 714 PM EST WED FEB 27 2013
DECIDED TO GO WITH AN ADVISORY FOR MARQUETTE COUNTY. LOOKING AT
PRESENT RADAR TRENDS...MORE ENHANCEMENT IS OCCURRING TO THE EAST OF
THE AREA AND IS HEADED THIS WAY. INTENSITY OF THE SNOW WITH UPSLOPE
FLOW HAS INCREASED ACROSS MARQUETTE COUNTY AS WELL AND HAD A REPORT
EARLIER AT 630 OF 3 INCHES OF SNOW IN HARVEY. NOT OUT OF THE
QUESTION THAT SOME AREAS COULD SEE 5 INCHES OF SNOW BEFORE THIS IS
ALL OVER. SYSTEM MOISTURE WILL PULL OUT AFTER MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 426 PM EST WED FEB 27 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A BROAD MID LEVEL LOW
CIRCULATION OVER THE GREAT LAKES/OHIO VALLEY. AT THE SFC...A
WEAKENING LOW PRES CENTER WAS LOCATED NEAR FLINT. SYSTEM ENDED UP
SLIGHTLY FARTHER N THAN EXPECTED YESTERDAY...AND THUS THE ASSOCIATED
WEAKENING SNOW SHIELD WAS ABLE TO SPREAD FARTHER N AND W INTO UPPER
MI TODAY...AIDED BY A SHORTWAVE THAT PIVOTED AROUND THE LARGE MID
LEVEL LOW CIRCULATION. THE NW EDGE OF THE -SN HAS SPREAD TO ABOUT A
BIG BAY/CHAMPION/CRYSTAL FALLS LINE. SNOW ACCUMULATIONS HAVE
GENERALLY BEEN 1 INCH OR LESS THOUGH SOME 2-3 INCH AMOUNTS WERE
OBSERVED ACROSS MENOMINEE/DELTA/SRN SCHOOLCRAFT COUNTIES. SINCE THE
WEAKENING SHORTWAVE AND ASSOCIATED DEEP LAYER FORCING ASSOCIATED
WITH THE HEAVIER SNOW HAS ROTATED TO THE SW...-SN HAS BEEN
DIMINISHING IN AREAL COVERAGE FROM LATE MORNING THRU THE AFTN. AS
EXPECTED...THERE HAS NOT BEEN ANY EVIDENCE OF LES TODAY DESPITE
CYCLONIC NE FLOW AS AIR MASS HAS BEEN TOO WARM. IN FACT...ON VIS
SATELLITE IMAGERY...HIGH CLOUDS ARE AT TIMES THIN ENOUGH TO REVEAL
LITTLE IF ANY LAKE EFFECT CLOUDS OVER LAKE SUPERIOR. THE SNOW THAT
HAS RECENTLY INCREASED INTO NCNTRL UPPER MI APPEARS MOSTLY RELATED
TO A LONG ARC OF ISENTROPIC ASCENT EXTENDING W FROM NEW ENGLAND...
BUT IT CERTAINLY LOOKS LIKE THERE MAY NOW BE A LAKE COMPONENT TO
THIS HEAVIER SNOW THAT HAS DEVELOPED.
IN THE SHORT TERM...FOCUS SHIFTS FROM REMNANT -SN ASSOCIATED WITH
SLOWLY DEPARTING GREAT LAKES/OHIO VALLEY MID LEVEL LOW TO POTENTIAL
OF LES OFF LAKE SUPERIOR. WITH NO ADDITIONAL SHORTWAVES EVIDENT
PIVOTING TOWARD UPPER MI AND WITH MODELS INDICATING INCREASING DEEP
LAYER QVECTOR CONVERGENCE WITH TIME...EXPECT LINGERING AREAS OF -SN
OVER ROUGHLY THE E HALF OF UPPER MI TO CONTINUE TO DIMINISH TONIGHT.
ANY ADDITIONAL SNOW ACCUMULATION WILL BE LESS THAN 1 INCH.
ATTENTION THEN TURNS TO POTENTIAL LES OFF LAKE SUPERIOR. HIGHER RES
MODEL GUIDANCE CONTINUES TO POINT TOWARD LES/UPSLOPE ENHANCED SNOW
TONIGHT. ALTHOUGH DEEPER MOISTURE/SATURATION AND SYNOPTIC -SN IS
SPREADING OUT OVER ERN LAKE SUPERIOR...HAVE DOUBTS ON THE INSISTENCE
OF HIGH RES GUIDANCE TO OUTPUT IN WHAT SOME CASES ARE SIGNIFICANT
PCPN TOTALS TONIGHT (REGIONAL GEM SHOWS AROUND 0.5 INCHES OF PCPN
TONIGHT OVER THE HIGHER TERRAIN OF MARQUETTE COUNTY...LOCAL HIGH
RESWRF 0.3-0.4...06Z NAM SHOWED UPWARDS OF 1 INCH BUT 12Z NAM AT
LEAST TRENDED DOWN TO WHAT SHOULD BE A MORE REASONABLE 0.2-0.3).
850MB TEMPS OF ONLY -6 TO -9C ACROSS LAKE SUPERIOR WILL NOT BE
SUFFICIENT FOR LES. SO...ONCE THE ISENTROPIC ASCENT CURRENTLY AIDING
THE SNOW INTO NCNTRL UPPER MI FALLS APART TONIGHT...EXPECT THE SNOW
TO DIMINISH SIGNIFICANTLY. WILL THUS CARRY HIGH POPS INTO NCNTRL
UPPER MI THIS EVENING...THEN DIMINISH PCPN TO JUST SCT -SHSN
OVERNIGHT. EXPECT A FEW INCHES OF SNOW ACCUMULATION THRU THE EVENING
ACROSS THE HIGHER TERRAIN OF THE NCNTRL (MARQUETTE COUNTY IN
PARTICULAR). IF THE ONGOING SNOW SHOWS SIGNS OF PERSISTENCE AND
LITTLE MOVEMENT (HEAVIEST SNOW IS CURRENTLY OCCURRING FROM
MARQUETTE/HARVEY WSW TO ISHPEMING/GWINN) WILL LIKELY NEED TO HOIST
AN ADVY. FARTHER W...LACKING SYNOPTIC FORCING...NOTHING MORE THAN
DEVELOPING CHC POPS/SCT -SHSN APPEAR REASONABLE.
850MB TEMPS FALL ANOTHER DEGREE OR TWO THU...BUT EVEN THAT WILL
STILL NOT BE QUITE COLD ENOUGH FOR LES. WITH ANY DEEPER MOISTURE
EXITING AND SINCE THERE WILL PROBABLY BE SOME NEGATIVE IMPACT DUE TO
DAYTIME HEATING WITH HIGHER SUN ANGLE AT THIS TIME OF YEAR...SCT
-SHSN OFF THE LAKE SHOULD WIND DOWN DURING THE DAY.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 426 PM EST WED FEB 27 2013
PREFERRED THE 00Z/27 ECMWF AND GLOBAL GEM OVER THE 12Z/27 GFS FOR
THE ENTIRE LONG TERM SINCE THE GFS HAS DISPLAYED POOR RUN TO RUN
CONTINUITY AND LACKS AGREEMENT WITH OTHER MODELS.
KEPT DIMINISHING CHANCES OF LAKE EFFECT SNOW THU NIGHT INTO EARLY
FRI IN AREAS FAVORED BY NE LOW LEVEL WINDS...BUT PUSHED BACK WHEN
POPS GO AWAY ENTIRELY BY AROUND 3 HOURS TO 18Z FRI. AFTER
THAT...VERY DRY LOW LEVELS ASSOCIATED WITH A SFC AND 500MB RIDGE
PUSHING INTO THE CWA. LOW LEVEL FLOW WILL CONTINUE TO BE OUT OF THE
N/NE UNTIL THE SFC RIDGE AXIS COMPLETELY PASSES SUN NIGHT WITH
SLIGHTLY COLDER 850MB TEMPS...SO WILL KEEP INCREASED CLOUD COVER NEAR
LAKE SUPERIOR. MAY SEE A BRIEF RETURN OF NE FLOW LES LATE FRI NIGHT
WITH THE PASSAGE OF A 500MB TROUGH...BUT ANY ACCUMULATIONS WILL BE
MINOR.
THE STORY FOR SUN THROUGH NEXT WED IS THAT A 500MB LOW WILL MOVE
OVER THE CWA THROUGH TUE BEFORE MOVE S ON WED. AT THE SAME
TIME...INCREASINGLY STRONG SFC RIDGING WILL MOVE INTO THE CWA...SO
PRECIP WILL BE AT A MINIMUM. PRECIP...IF ANY...WILL BE MINOR SO
SLIGHT CHANCE POPS AT BEST SEEM APPROPRIATE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 215 AM EST THU FEB 28 2013
WIND DIRECTION IS MOST FAVORABLE FOR ENHANCED WINDS AT KSAW...AND
GUSTS THERE SHOULD BE IN THE 20-30KT RANGE THROUGHOUT THE FCST
PERIOD. AT KIWD...UPSLOPE N/NNE WINDS WILL LIKELY KEEP LOW MVFR CIGS
IN PLACE THRU THE FCST PERIOD. AS AIR MASS COOLS SLIGHTLY... LAKE
EFFECT -SHSN MAY GET UNDERWAY OVERNIGHT...BUT EXPECTATION IS FOR ANY
SHSN TO BE LIGHT AND NOT SIGNIFICANTLY REDUCE VIS. AT KCMX... MVFR
CIGS AT KCMX WILL CONTINUE. MAY SEE A FEW FLURRIES LATER TONIGHT AT
KCMX. AT KSAW...IDEAL UPSLOPE FLOW AND PERIODS OF -SN SHOULD RESULT
IN IFR CONDITIONS PREVAILING FOR THE NEXT SEVERAL HRS. SOME
IMPROVEMENT TO LOW MVFR SHOULD OCCUR BY MORNING WITH LOW MVFR
CONDITIONS CONTINUING THRU THE PERIOD UNDER UPSLOPE NORTHERLY FLOW.
WILL GO WITH PERSISTENCE FOR THIS FORECAST.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 426 PM EST WED FEB 27 2013
TIGHT PRES GRADIENT BTWN HIGH PRES TO THE N AND NW AND LOW PRES
TRACKING THRU THE LWR LAKES WILL RESULT IN NORTHEASTERLY WINDS OF
20-30KT ACROSS LAKE SUPERIOR THRU THU. GALE FORCE GUSTS SHOULD BE
FREQUENT ENOUGH TO MAINTAIN GALE WARNING FOR THE E HALF OF LAKE
SUPERIOR. IN ADVANCE OF HIGH PRES RIDGE BUILDING TOWARD THE AREA
FRI...TIGHT PRES GRADIENT WILL REMAIN...RESULTING IN CONTINUED
20-30KT NE WINDS. THE STRONG WINDS/HIGH WAVES AND INFLUX OF COLDER
AIR WILL RESULT IN FREEZING SPRAY DEVELOPING TONIGHT AND CONTINUING
THRU FRI NIGHT. HVY FREEZING SPRAY MAY OCCUR FOR A TIME THU
NIGHT/FRI MORNING. WINDS WILL THEN DIMINISH FROM W TO E FRI NIGHT AS
HIGH PRES RIDGE MOVES CLOSER. ON SAT...WINDS SHOULD BE BLO 20KT
ACROSS THE ENTIRE LAKE. LIGHT WINDS...MOSTLY 10KT OR LESS...ARE
EXPECTED SUN/MON AS SFC HIGH PRES RIDGE WILL EXTEND FROM HUDSON BAY
S ACROSS THE UPPER LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR MIZ005.
LAKE SUPERIOR...
GALE WARNING UNTIL 10 AM EST THIS MORNING FOR LSZ244-245-248>250-
264>267.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...07
SHORT TERM...ROLFSON
LONG TERM...TITUS
AVIATION...07
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
305 AM CST THU FEB 28 2013
.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 305 AM CST THU FEB 28 2013
THROUGH 12Z FRIDAY...BROAD AREA OF FRONTOGENESIS REMAINS FIXED
ACROSS NORTH CENTRAL NEBRASKA EARLY THIS MORNING WITH PROGRESSIVE
NORTHWESTERLY FLOW ALOFT USHERING IN A STEADY FEED OF MOISTURE.
STRATUS HAS BACKED WEST THIS MORNING...AS KTIF...KVTN AND POINTS
EAST ARE NOW REPORTING OVC012 OR LOWER. NEAR TERM SOLUTIONS SEEM TO
HAVE A GOOD HANDLE AT THIS POINT WITH THE STRATUS...HOWEVER THE 06Z
RAP RUN SEEMS TO BE A BIT TOO AMBITIOUS WITH THE WESTERN EXTENT OF
THE LOWER CEILINGS...WHEREAS THE 00Z NAM IS SLIGHTLY EAST. FELT THAT
A BLEND OF THE TWO BEST REPRESENTS THE CURRENT CONDITIONS...AND THUS
WILL EMPLOY THE BLEND THROUGH MIDDAY TODAY. WITH THIS
BLEND...STRATUS IS INDICATED TO REMAIN ACROSS MUCH OF NORTH CENTRAL
NEBRASKA AND THE EASTERN SANDHILLS FOR MUCH OF THE DAY. BECAUSE OF
THE CLOUD COVER...HIGH TEMPERATURES MAY ONCE AGAIN STRUGGLE TO REACH
0C EAST OF AN AINSWORTH TO BARTLETT LINE. WEST...ACROSS THE SAND
HILLS AND EASTERN PANHANDLE NEBRASKA...WAA IN THE LOW TO MID LEVELS
AND CLEARING SHOULD PROVIDE FOR TEMPERATURES ABOVE 40F.
FOR THIS EVENING AND OVERNIGHT...INHERITED FORECAST INDICATED THE
POTENTIAL OF --SN ACROSS NORTHERN PORTIONS OF THE CWA. THERE IS A
WEAK UPPER LEVEL SHORTWAVE PROGGED TO PASS THROUGH NORTHWESTERLY
FLOW THAT WILL INCREASE LIFT AND PROVIDE FOR A BRIEF PERIOD OF
SATURATION WITHIN THE DENDRITIC LAYER. LIFT IS WEAK WITH THIS
WAVE...AND DEEP MOISTURE IS LACKING...SO GOING WITH THE
LIGHT/NON-MEASURABLE PRECIPITATION SEEMS THE BEST WAY TO HANDLE THIS
AT THIS POINT IN TIME.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 305 AM CST THU FEB 28 2013
AN UPPER LEVEL DISTURBANCE WILL DIVE SOUTHEAST ACROSS THE AREA
FRIDAY MORNING. SOME VERY WEAK LIFT AND A RATHER MOIST DENDRITIC
LAYER COULD YIELD A FEW FLURRIES BEFORE NOON...OTHERWISE CLOUDS
SHOULD DECREASE DURING THE AFTERNOON AS THE SYSTEM CONTINUES MOVING
SOUTHEAST AWAY FROM THE AREA. AT THE SURFACE...A STATIONARY FRONT
WILL REMAIN ANCHORED FROM NORTH TO SOUTH ACROSS WESTERN NEBRASKA.
THIS FRONT WILL PUSH EAST INTO CENTRAL NEBRASKA SATURDAY...AND
EASTERN NEBRASKA BY SUNDAY. WESTERLY DOWNSLOPE WINDS TO THE WEST OF
THE FRONT WILL BRING 50 DEGREE HIGHS TO WESTERN NEBRASKA
SATURDAY...SPREADING INTO CENTRAL NEBRASKA BY SUNDAY. A 60 DEGREE
READING OR TWO CANNOT BE RULED OUT BY SUNDAY ACROSS FAR SOUTHWEST
NEBRASKA...AS SNOWPACK WILL BE DWINDLING BY THIS TIME.
MONDAY INTO TUESDAY STILL LOOKS INTERESTING. ALL MODELS DROP A
COMPACT CLOSED LOW SOUTHEAST ACROSS THE CENTRAL AND NORTHERN PLAINS.
MODELS HAVE BEEN STRUGGLING WITH THE TRACK OF THE SYSTEM...BUT THE
LATEST 00Z SUITE ARE ACTUALLY ALL FAIRLY CLOSE TOGETHER...AND TRACK
THE CENTER OF THE SYSTEM SOUTHEAST ACROSS NORTHERN NEBRASKA. THE
ECMWF IS FARTHEST SOUTH WITH A TRACK FROM CHADRON TO FALLS
CITY...AND THE GFS IS JUST NORTH OF THIS TRACK ALONG THE NEB/SD
BORDER. MOST OF THE PRECIPITATION WILL FALL TO THE NORTH OF THE
TRACK...SO THE ECMWF SOLUTION WOULD BRING THE HIGHEST POTENTIAL
FOR SOME ACCUMULATING SNOW TO NORTHERN NEBRASKA. ANOTHER THING TO
WATCH WITH THIS SYSTEM IS THE WIND POTENTIAL. THE GFS REALLY
CRANKS UP THE 850 MB WIND SPEEDS /NEAR 55 KTS/ ON THE BACKSIDE OF
THE LOW ACROSS WESTERN NEBRASKA...THE ECMWF IS LESS IMPRESSIVE.
BOTTOM LINE HERE IS THAT WE WILL CONTINUE TO MONITOR THE LATEST
TREND IN THE MODELS. A SHIFT FARTHER SOUTH WOULD MEAN LESS WIND
BUT MORE SNOWFALL POTENTIAL...AND A SHIFT NORTH WOULD MEAN VERY
LITTLE PRECIPITATION BUT MORE WIND.
BY MID WEEK A WARMING TREND WILL DEVELOP ONCE AGAIN AHEAD OF A
DEVELOPING LONG WAVE TROUGH ACROSS THE WESTERN CONUS. SOUTHERLY
WINDS WILL BEGIN TO TRANSPORT MOISTURE NORTHWARD BY WEEKS
END...POSSIBLE LEADING TO PRECIPITATION BY THE WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 305 AM CST CST THU FEB 28 2013
MVFR CEILINGS ARE FORECAST TO PERSIST AT KVTN UNTIL 18Z/28TH. WHILE
THERE COULD BE TIMES WHEN CEILINGS GO VFR...THE RAP MODEL SEEM TO BE
HANDLING THE AREAS OF STRATUS BEST...KEEPING KVTN WITHIN THE STRATUS
AREA. KLBF SHOULD CONTINUE TO REMAIN IN VFR CONDITIONS THROUGH THE
PERIOD. CURRENT HIGH CLOUDINESS SHOULD THIN BY MID MORNING. SURFACE
WINDS SHOULD REMAIN LIGHT NORTHWEST BELOW 10KT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JACOBS
LONG TERM...TAYLOR
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
135 AM CST THU FEB 28 2013
.SYNOPSIS...
ISSUED AT 253 PM CST WED FEB 27 2013
ANALYSIS OF THE 20Z MSL DATA SHOWED A FRONT ACROSS SOUTH DAKOTA TO A
LOW IN SOUTHEAST MONTANA. A WARM FRONT THEN EXTENDS THROUGH ALBERTA
AND BRITISH COLUMBIA TO A WAVE NORTHWEST OF VANCOUVER ISLAND AND
EVENTUALLY TO A LOW ON THE ALEUTIAN ISLANDS. WATER VAPOR IMAGERY
INDICATED A MATURING VORTEX IN THE PACIFIC NORTHWEST OF VANCOUVER
ISLAND AND ANOTHER BROAD CYCLONIC CIRCULATION ACROSS THE ALEUTIAN
CHAIN. NEARER TO HOME...A DEVELOPING WAVE WAS INDICATED IN THE WATER
VAPOR LOOP OVER NORTHEAST MONTANA. ANOTHER BROAD CYCLONIC
&&
.UPDATE...
ISSUED AT 130 AM CST THU FEB 28 2013
MADE ONLY MINOR REVISIONS TO THE FIRST 36 HRS OF THE
FORECAST...MAINLY TO ACCOUNT FOR THE STRATUS BACKING ACROSS
PORTIONS OF THE CENTRAL SANDHILLS AT THIS HOUR. STILL WATCHING FOR
THE POTENTIAL OF A FLURRY OR TWO THIS EVENING/OVERNIGHT AS A WEAK
DISTURBANCE DROPS THROUGH NORTHWESTERLY FLOW. PROXIMITY SOUNDINGS
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA REVEAL A BRIEF PERIOD OF
SATURATION WITHIN THE DENDRITIC LAYER...THUS WILL MAINTAIN THE
FLURRY MENTION THOUGH CONFIDENCES IN ANY NOTICEABLE QPF IS LOW.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 253 PM CST WED FEB 27 2013
FORECAST CONCERNS THROUGH THURSDAY ARE CLOUD COVER AND TEMPERATURES.
BAND OF STRATUS EXTENDED FROM WESTERN NORTH DAKOTA THROUGH WESTERN
AND CENTRAL NEBRASKA ON WEDNESDAY AFTERNOON. THIS IS IN AN AREA OF
BROAD FRONTOGENESIS...AND WITH NORTHERLY FLOW CONTINUING TO BRING
THIS MOISTURE SOUTH THROUGH TONIGHT...WILL KEEP THE CLOUD COVER IN
THIS SAME VICINITY. GOING INTO THURSDAY...A WEAK BOUNDARY IN THE LOW
LEVELS WILL REMAIN NEARLY STATIONARY ACROSS WESTERN NEBRASKA.
BELIEVE THE CORRIDOR OF WEAK FLOW WILL KEEP THE CLOUDS FROM ERODING
AND MAY KEEP THE STRATUS IN PLACE THROUGH MID DAY. BECAUSE OF THE
CLOUD COVER...DID BUMP TEMPERATURES UP A FEW DEGREES TONIGHT ACROSS
THE AREA WITH HIGHER CLOUD COVER AND THEN DID ADJUST HIGHS DOWN A
FEW DEGREES ON THURSDAY. WINDS WILL DIMINISH THIS EVENING ACROSS
MUCH OF THE FORECAST AREA...BUT NORTH CENTRAL NEBRASKA WILL KEEP
SOME BREEZY CONDITIONS THROUGH THE OVERNIGHT HOURS AND INTO
THURSDAY. HAVE ADDED SOME ISOLATED FLURRIES OR SPRINKLES TO THE
FORECAST FOR THURSDAY AFTERNOON OVER THE FAR NORTHWEST PART OF THE
FORECAST AREA AS A WEAK UPPER LEVEL SHORTWAVE TROUGH /CURRENTLY OVER
WESTERN MONTANA/ MOVES ACROSS SOUTHERN SOUTH DAKOTA. ALTHOUGH LIFT
ISN/T SUBSTANTIAL...AND MOISTURE IS LIMITED...BUT WITH THE NORTHWEST
FLOW...FELT IT WASN/T OUT OF THE QUESTION TO PUT IN THE LIGHT AND
NON-MEASURABLE PRECIPITATION.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 253 PM CST WED FEB 27 2013
ANOTHER SURGE OF COLD AIR WILL GENERATE SOME SYSTEM-RELATIVE
ISENTROPIC LIFT LATE THURSDAY NIGHT AND EARLY FRIDAY. AIR IN THE
285-295K LAYER IS NEARLY SATURATED WITH SATURATION DEFICITS OF 30MB
OR LOWER...BUT THE MIXING RATIOS ARE MOSTLY 2G/KG OR LOWER. LOOKING
IN THE DENDRITIC LAYER...UPWARD MOTION IS INDICATED WITH LAYER
RELATIVE HUMIDITY GREATER THAN 90 PERCENT. THEREFORE...SNOW CRYSTAL
FORMATION IS LIKELY. THE FORECAST SOUNDING INDICATES A PSEUDO-
ADIABATIC LAPSE RATE IN SATURATED AIR...SO SOME INSTABILITY IS
PRESENT AND SOME ACCRETION COULD BE EXPECTED. HOWEVER...WITH LITTLE
MOISTURE IN THE LOWER LAYERS...MOISTURE CONTENT WILL BE MINIMAL. AS
A RESULT...WE WILL INCLUDE ONLY FLURRIES IN THE FORECAST FOR
THURSDAY NIGHT AFTER MIDNIGHT AND FRIDAY.
FOR SATURDAY AND SUNDAY...AN UPPER RIDGE ACROSS THE WESTERN U.S.
WILL KEEP THE WEATHER IN NEBRASKA DRY AND UNSEASONABLY WARM.
THE NEXT SYSTEM OF NOTE IS A FAIRLY STRONG CLIPPER-TYPE SYSTEM
MONDAY AND MONDAY NIGHT. AN UPPER SYSTEM COMING FROM THE NORTH
PACIFIC AND ACROSS THE ROCKIES IN ALBERTA WILL TRIGGER LEE SIDE
CYCLOGENESIS IN SOUTHERN ALBERTA. THE CYCLONE WILL THEN MAKE ITS WAY
INTO THE NORTHERN U.S. AND ACROSS SOUTH DAKOTA AND NEBRASKA.
MOISTURE TRANSPORT VECTORS IN THE 290-300K LAYER SHOW MID-LEVEL
MOISTURE FROM THE PACIFIC CROSSING THE ROCKIES AND SATURATING MIDDLE
LEVELS BY SUNDAY EVENING 00Z. THIS WOULD HAVE MOISTURE IN PLACE FOR
THE STORM SYSTEM COMING ONTO THE NORTHERN PLAINS FROM ALBERTA. AN
EAST-WEST CROSS SECTION INDICATES DRY LOWER LAYERS
INITIALLY...SATURATING TOP DOWN MONDAY AFTERNOON. THE TOP-DOWN
SATURATION WILL RESULT IN FAIRLY RAPID COOLING IN THE BOUNDARY
LAYER. SO...IT LOOKS LIKE IT WILL BEGIN AS RAIN AND CHANGE OVER
QUICKLY TO SNOW BY LATE AFTERNOON OR EARLY EVENING. WITH THE TRACK
OF THE CYCLONE EXPECTED TO BE ACROSS NORTHERN NEBRASKA...THE BEST
CHANCES OF SIGNIFICANT PRECIPITATION WILL BE NORTHERN NEBRASKA.
THERE IS STILL SOME UNCERTAINTY WITH THE ECMWF INDICATING A TRACK
ACROSS SOUTHERN SOUTH DAKOTA...THE GFS INDICATING A TRACK ACROSS
CENTRAL NEBRASKA AND THE GEM INDICATING A TRACK ACROSS NORTHERN
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1115 PM CST WED FEB 27 2013
MVFR CEILINGS ARE FORECAST TO PERSIST AT KVTN UNTIL 18Z/28TH.
WHILE THERE COULD BE TIMES WHEN CEILINGS GO VFR...THE RAP MODEL
SEEM TO BE HANDLING THE AREAS OF STRATUS BEST...KEEPING KVTN
WITHIN THE STRATUS AREA. KLBF SHOULD CONTINUE TO REMAIN IN VFR
CONDITIONS THROUGH THE PERIOD. CURRENT HIGH CLOUDINESS SHOULD THIN
BY MID MORNING. SURFACE WINDS SHOULD REMAIN LIGHT NORTHWEST BELOW
10KT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JACOBS
SYNOPSIS...SPRINGER
SHORT TERM...BROOKS
LONG TERM...SPRINGER
AVIATION...ROBERG
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1115 PM CST WED FEB 27 2013
.SYNOPSIS...
ISSUED AT 253 PM CST WED FEB 27 2013
ANALYSIS OF THE 20Z MSL DATA SHOWED A FRONT ACROSS SOUTH DAKOTA TO A
LOW IN SOUTHEAST MONTANA. A WARM FRONT THEN EXTENDS THROUGH ALBERTA
AND BRITISH COLUMBIA TO A WAVE NORTHWEST OF VANCOUVER ISLAND AND
EVENTUALLY TO A LOW ON THE ALEUTIAN ISLANDS. WATER VAPOR IMAGERY
INDICATED A MATURING VORTEX IN THE PACIFIC NORTHWEST OF VANCOUVER
ISLAND AND ANOTHER BROAD CYCLONIC CIRCULATION ACROSS THE ALEUTIAN
CHAIN. NEARER TO HOME...A DEVELOPING WAVE WAS INDICATED IN THE WATER
VAPOR LOOP OVER NORTHEAST MONTANA. ANOTHER BROAD CYCLONIC
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 253 PM CST WED FEB 27 2013
FORECAST CONCERNS THROUGH THURSDAY ARE CLOUD COVER AND TEMPERATURES.
BAND OF STRATUS EXTENDED FROM WESTERN NORTH DAKOTA THROUGH WESTERN
AND CENTRAL NEBRASKA ON WEDNESDAY AFTERNOON. THIS IS IN AN AREA OF
BROAD FRONTOGENESIS...AND WITH NORTHERLY FLOW CONTINUING TO BRING
THIS MOISTURE SOUTH THROUGH TONIGHT...WILL KEEP THE CLOUD COVER IN
THIS SAME VICINITY. GOING INTO THURSDAY...A WEAK BOUNDARY IN THE LOW
LEVELS WILL REMAIN NEARLY STATIONARY ACROSS WESTERN NEBRASKA.
BELIEVE THE CORRIDOR OF WEAK FLOW WILL KEEP THE CLOUDS FROM ERODING
AND MAY KEEP THE STRATUS IN PLACE THROUGH MID DAY. BECAUSE OF THE
CLOUD COVER...DID BUMP TEMPERATURES UP A FEW DEGREES TONIGHT ACROSS
THE AREA WITH HIGHER CLOUD COVER AND THEN DID ADJUST HIGHS DOWN A
FEW DEGREES ON THURSDAY. WINDS WILL DIMINISH THIS EVENING ACROSS
MUCH OF THE FORECAST AREA...BUT NORTH CENTRAL NEBRASKA WILL KEEP
SOME BREEZY CONDITIONS THROUGH THE OVERNIGHT HOURS AND INTO
THURSDAY. HAVE ADDED SOME ISOLATED FLURRIES OR SPRINKLES TO THE
FORECAST FOR THURSDAY AFTERNOON OVER THE FAR NORTHWEST PART OF THE
FORECAST AREA AS A WEAK UPPER LEVEL SHORTWAVE TROUGH /CURRENTLY OVER
WESTERN MONTANA/ MOVES ACROSS SOUTHERN SOUTH DAKOTA. ALTHOUGH LIFT
ISN/T SUBSTANTIAL...AND MOISTURE IS LIMITED...BUT WITH THE NORTHWEST
FLOW...FELT IT WASN/T OUT OF THE QUESTION TO PUT IN THE LIGHT AND
NON-MEASURABLE PRECIPITATION.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 253 PM CST WED FEB 27 2013
ANOTHER SURGE OF COLD AIR WILL GENERATE SOME SYSTEM-RELATIVE
ISENTROPIC LIFT LATE THURSDAY NIGHT AND EARLY FRIDAY. AIR IN THE
285-295K LAYER IS NEARLY SATURATED WITH SATURATION DEFICITS OF 30MB
OR LOWER...BUT THE MIXING RATIOS ARE MOSTLY 2G/KG OR LOWER. LOOKING
IN THE DENDRITIC LAYER...UPWARD MOTION IS INDICATED WITH LAYER
RELATIVE HUMIDITY GREATER THAN 90 PERCENT. THEREFORE...SNOW CRYSTAL
FORMATION IS LIKELY. THE FORECAST SOUNDING INDICATES A PSEUDO-
ADIABATIC LAPSE RATE IN SATURATED AIR...SO SOME INSTABILITY IS
PRESENT AND SOME ACCRETION COULD BE EXPECTED. HOWEVER...WITH LITTLE
MOISTURE IN THE LOWER LAYERS...MOISTURE CONTENT WILL BE MINIMAL. AS
A RESULT...WE WILL INCLUDE ONLY FLURRIES IN THE FORECAST FOR
THURSDAY NIGHT AFTER MIDNIGHT AND FRIDAY.
FOR SATURDAY AND SUNDAY...AN UPPER RIDGE ACROSS THE WESTERN U.S.
WILL KEEP THE WEATHER IN NEBRASKA DRY AND UNSEASONABLY WARM.
THE NEXT SYSTEM OF NOTE IS A FAIRLY STRONG CLIPPER-TYPE SYSTEM
MONDAY AND MONDAY NIGHT. AN UPPER SYSTEM COMING FROM THE NORTH
PACIFIC AND ACROSS THE ROCKIES IN ALBERTA WILL TRIGGER LEE SIDE
CYCLOGENESIS IN SOUTHERN ALBERTA. THE CYCLONE WILL THEN MAKE ITS WAY
INTO THE NORTHERN U.S. AND ACROSS SOUTH DAKOTA AND NEBRASKA.
MOISTURE TRANSPORT VECTORS IN THE 290-300K LAYER SHOW MID-LEVEL
MOISTURE FROM THE PACIFIC CROSSING THE ROCKIES AND SATURATING MIDDLE
LEVELS BY SUNDAY EVENING 00Z. THIS WOULD HAVE MOISTURE IN PLACE FOR
THE STORM SYSTEM COMING ONTO THE NORTHERN PLAINS FROM ALBERTA. AN
EAST-WEST CROSS SECTION INDICATES DRY LOWER LAYERS
INITIALLY...SATURATING TOP DOWN MONDAY AFTERNOON. THE TOP-DOWN
SATURATION WILL RESULT IN FAIRLY RAPID COOLING IN THE BOUNDARY
LAYER. SO...IT LOOKS LIKE IT WILL BEGIN AS RAIN AND CHANGE OVER
QUICKLY TO SNOW BY LATE AFTERNOON OR EARLY EVENING. WITH THE TRACK
OF THE CYCLONE EXPECTED TO BE ACROSS NORTHERN NEBRASKA...THE BEST
CHANCES OF SIGNIFICANT PRECIPITATION WILL BE NORTHERN NEBRASKA.
THERE IS STILL SOME UNCERTAINTY WITH THE ECMWF INDICATING A TRACK
ACROSS SOUTHERN SOUTH DAKOTA...THE GFS INDICATING A TRACK ACROSS
CENTRAL NEBRASKA AND THE GEM INDICATING A TRACK ACROSS NORTHERN
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1115 PM CST WED FEB 27 2013
MVFR CEILINGS ARE FORECAST TO PERSIST AT KVTN UNTIL 18Z/28TH.
WHILE THERE COULD BE TIMES WHEN CEILINGS GO VFR...THE RAP MODEL
SEEM TO BE HANDLING THE AREAS OF STRATUS BEST...KEEPING KVTN
WITHIN THE STRATUS AREA. KLBF SHOULD CONTINUE TO REMAIN IN VFR
CONDITIONS THROUGH THE PERIOD. CURRENT HIGH CLOUDINESS SHOULD THIN
BY MID MORNING. SURFACE WINDS SHOULD REMAIN LIGHT NORTHWEST BELOW
10KT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SPRINGER
SHORT TERM...BROOKS
LONG TERM...SPRINGER
AVIATION...ROBERG
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
847 AM EST THU FEB 28 2013
.SYNOPSIS...
LOW PRESSURE WILL DRIFT EAST FROM THE GREAT LAKES TO NEW ENGLAND
THROUGH THE END OF THE WEEK. AN UPPER LEVEL TROUGH WILL THEN
PERSIST OVER THE EASTERN STATES THROUGH THE WEEKEND. HIGH PRESSURE
IS EXPECTED EARLY NEXT WEEK. LOW PRESSURE LOOKS TO APPROACH THE
MID-ATLANTIC AROUND THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
WITH A LARGE UPPER CLOSED LOW HANGING OVER THE GREAT LAKES AND UPPER
MIDWEST...CONTINUED WAVES OF CLOUDS AND PERIODIC SHOWERS WILL SLIDE
OVER THE REGION. THE WARM SIDE OF THE SYSTEM MOVED ACROSS THE REGION
ON TUE...BUT IS NOW WELL NORTH AND EAST OF THE AREA. AT THIS
POINT...THE MID ATLC IS ON THE SOUTHEASTERN QUADRANT OF THIS LARGE
ENCOMPASSING UPPER FEATURE. MUCH SMALLER-SCALE WAVES OF WEAK LIFT
AND MOISTURE CONVERGENCE HAVE BEEN AND WILL CONTINUE TO GENERATE
LIGHT SHOWERS ACROSS THE LOWLANDS AND MINOR ACCUMULATIONS OF UPSLOPE
SNOW SHOWERS FOR THE MTNS. SAME STORY AT THE MOMENT...W/ BATCHES OF
LIGHT RAIN DEVELOPING OVER THE VA/MD PIEDMONT SINCE MIDNIGHT. SOME
LIGHT SHOWERS WILL AFFECT THE DC/BALT AREAS AND BACK TOWARD THE BLUE
RIDGE...SLOWLY DRIFTING TOWARD THE EAST THRU DAWN.
NEAR TERM GUIDANCE...ESPEC THE HRRR WHICH RECENT RUNS APTLY DEPICTED
THE CURRENT ACTIVITY...SHOW ANOTHER BATCH OF MOISTURE CONVERGENCE
ACROSS THE I-95 CORRIDOR LATER THIS MRNG - TOWARD EARLY AFTN. THIS
WOULD LEAVE A DRY MORNING FROM AROUND DAWN THRU AROUND NOON BEFORE
THE NEXT BATCH OF SCATTERED SHOWERS DEVELOPS. RELATIVELY MILD
OVERNIGHT LOWS IN THE U30S-L40S WILL GRADUALLY RISE TOWARD THE U40S
TO AROUND 50 BY MID AFTN. WLY WINDS WILL AGAIN PICK UP IN THE
AFTN...ONLY CUTTING DOWN THE APPARENT TEMPS BY A FEW DEGREES BUT NOT
PARTICULARLY WINDY - MAINLY A 15-20MPH BREEZE.
BACKING OUT TO A LARGER VIEW AGAIN - THE PARENT UPPER LOW WILL BE
MAKING A SLOW/STEADY WOBBLE TOWARD THE SE OVER THE COURSE OF TODAY
AND INTO TONIGHT FROM UPSTATE NY. ONE OF THE MORE POTENT UPPER VORT
MAXES ASSOCIATED W/ THIS FEATURE WILL BE SWINGING DOWN AROUND THE
BACKSIDE OF THE LOW - DIRECTLY OVER THE REGION LATER TONIGHT. A
BRIEF PERIOD OF GUSTY NW WINDS WILL MOVE OVER THE AREA OVERNIGHT AND
HELP PUSH THE EARLIER PRECIP WELL OFF THE COAST AND DRY OUT THE
REGION HEADING INTO FRI.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
A CUTOFF LOW WILL REMAIN OVER NEW ENGLAND FRIDAY THROUGH FRIDAY
NIGHT WHILE THE UPPER-LEVEL TROUGH ASSOCIATED WITH THIS SYSTEM
REMAINS OVERHEAD.
A NORTHWEST FLOW BETWEEN SURFACE LOW PRESSURE NEAR THE CANADIAN
MARITIMES AND HIGH PRESSURE OVER THE CENTRAL CONUS WILL ALLOW FOR
CHILLY CONDITIONS. MAX TEMPS FRIDAY WILL RANGE FROM THE 20S IN
PORTIONS OF THE ALLEGHENY HIGHLANDS TO THE MIDDLE AND UPPER 40S NEAR
WASHINGTON AND BALTIMORE. MIN TEMPS FRIDAY NIGHT WILL RANGE FROM THE
TEENS IN THE ALLEGHENY HIGHLANDS TO THE LOWER AND MIDDLE 30S IN
DOWNTOWN WASHINGTON/BALTIMORE.
A BKN STRATO CU WILL CAUSE PARTLY TO MOSTLY CLOUDY SKIES. DRIER AIR
ASSOCIATED WITH THE NORTHWEST FLOW WILL KEEP DRY CONDITIONS ACROSS
THE REGION FOR MOST OF THE TIME. HOWEVER...A FEW SPRINKLES AND
FLURRIES ARE POSSIBLE FRIDAY AFTERNOON DUE TO LIMITED INSTABILITY
ASSOCIATED WITH DAYTIME HEATING.
FOR LOCATIONS ALONG AND WEST OF THE ALLEGHENY FRONT. AN UPSLOPE
COMPONENT TO THE LOW-LEVEL FLOW WILL LIKELY TRIGGER SNOW SHOWERS.
ACCUMULATIONS DURING THE DAY FRIDAY SHOULD BE LIGHT. SNOW SHOWERS
ARE POSSIBLE FRIDAY NIGHT...BUT ANY ACCUMULATION WILL BE LIGHT.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
UPR TROUGH AXIS DRIFTS EAST ACROSS THE MID-ATLANTIC SATURDAY THROUGH
SUNDAY WITH SFC PRESSURE BUILDING FROM THE WEST BEHIND THE AXIS.
BELOW NORMAL TEMPERATURES EXPECTED UNDER THE CANADIAN SOURCED
AIR...THOUGH ONLY 5 TO 10 DEGREES BELOW. MAX TEMPS LOW TO MID 40S
SATURDAY...THEN UPR 30S TO LOW 40S SUNDAY. DRY.
THE NEXT LOW LOOKS TO TRACK ACROSS THE MID-SOUTH STATES EARLY NEXT
WEEK AND IMPACT THE MID-ATLANTIC IN THE MIDDLE OF THE WEEK. WAY TOO
EARLY TO TAKE AN OPERATIONAL RUN VERBATIM /AKA THE 00Z ECMWF/...SO
WILL SIMPLY HAVE TO MONITOR THE POTENTIAL FOR LATE SEASON SNOW AS
THE DAYS PROGRESS.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
PLENTY OF CLOUD COVER OVERNIGHT AND THRU THE DAY TODAY. A FEW
SHOWERS WILL DRIFT OVER THE DC/BALT AREA THRU AROUND 12Z BUT THEN
DRY OUT FOR A FEW HRS. ANOTHER ROUND OF LIGHT SHOWERS EXPECTED
TOWARD THE EARLY AFTN HRS...LAST FOR A FEW HRS THEN ALSO DISSIPATE
AND EXIT TO THE EAST. A FEW NEAR 20KT GUSTS WILL AFFECT THE WRN HALF
OF THE AREA THIS AFTN...INCLUDING THE FOOTHILLS OF THE BLUE RIDGE
TOWARD KCHO AND KIAD. A GENERAL W-NW WIND WILL CONTINUE THRU THE
CURRENT TAF CYCLE.
VFR CONDITIONS ARE EXPECTED MOST OF THE TIME FRIDAY THROUGH THE
WEEKEND. HOWEVER...A BKN STRATOCU DECK MAY APPROACH 3KFT AT TIMES.
NORTHWEST WINDS ARE EXPECTED THROUGH THE PERIOD WITH GUSTS AROUND 15
TO 25 KNOTS.
&&
.MARINE...
LIGHT WINDS OVER THE WATERS...THOUGH SOME MARGINAL SCA GUSTS MAY
APPEAR DURING THE DAYTIME HRS TODAY. A GENERAL 10-15KT WLY BREEZE
WILL BE STEADY...BUT THE HIGHER GUSTS SHOULD HOLD OFF UNTIL
OVERNIGHT AND INTO EARLY FRI MRNG.
A NORTHWEST FLOW BETWEEN LOW PRESSURE NEAR THE CANADIAN MARITIMES
AND HIGH PRESSURE OVER THE CENTRAL CONUS WILL CONTINUE FRIDAY
THROUGH THE WEEKEND. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE
WATERS FRIDAY AND THE SMALL CRAFT ADVISORY MAY NEED TO BE EXTENDED
INTO SATURDAY FOR PORTIONS OF THE WATERS.
HIGH PRESSURE WILL BUILD TOWARD THE WATERS EARLY NEXT WEEK.
&&
.TIDES/COASTAL FLOODING...
A COASTAL FLOOD ADVISORY HAS BEEN ISSUED FOR THE TIDAL POTOMAC AT
ALEXANDRIA THIS MORNING...WHERE MINOR FLOODING IS EXPECTED AT HIGH
TIDE. IN SPITE OF NW WINDS...POSITIVE ANOMALIES HAVE NOT RECEDED
TO A LARGE DEGREE...IN FACT - MOST SITES ARE STILL AROUND OR JUST
BELOW ONE FT ABOVE AVG. THIS WILL KEEP AN ELEVATED RISK OF NEAR-
MINOR THRESHOLDS FOR THE NEXT HIGH TIDE CYCLE. BESIDES
ALEXANDRIA...NO OTHER SINGLE FORECAST POINT HAS FORECAST CRITERIA
BEING REACHED...THOUGH MOST ARE FAIRLY CLOSE. WILL CONTINUE TO
MONITOR THESE TRENDS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...COASTAL FLOOD ADVISORY UNTIL NOON EST TODAY FOR VAZ054.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST FRIDAY FOR ANZ530-
531-535-536-538-539.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST
FRIDAY FOR ANZ532>534-537-540>543.
&&
$$
SYNOPSIS...BAJ
NEAR TERM...GMS
SHORT TERM...BJL
LONG TERM...BAJ
AVIATION...BJL/GMS
MARINE...BJL/GMS
TIDES/COASTAL FLOODING...KCS
AREA FORECAST DISCUSSION
NWS DULUTH MN
901 AM CST THU FEB 28 2013
.UPDATE...EXTENDED FLURRIES/SNOW SHOWERS ALONG SOUTH SHORE OF LAKE
SUPERIOR THROUGH 18Z AS RADAR INDICATES CONTINUED SNOW OFF LAKE.
THIS PRECIP SHOULD END AS DRIER AIR PUSHES IN FROM NORTH LATER
THIS MORNING. REST OF FCST UNCHANGED.
&&
.PREV DISCUSSION... /ISSUED 554 AM CST THU FEB 28 2013/
AVIATION...12Z TAFS
MVFR CEILINGS COVERED THE NORTHLAND THIS MORNING...AND WILL SLOWLY
ERODE FROM THE NORTH TODAY. WE DELAYED THE CLEARING...AS SATELLITE
AND THE LATEST RAP BOTH SUGGEST CLEARING WILL TAKE LONGER. THERE
MAY BE SOME LIGHT SNOW OR FLURRIES IN SPOTS AS WELL...MAINLY OVER
NORTHWEST WISCONSIN.
PREV DISCUSSION... /ISSUED 240 AM CST THU FEB 28 2013/
SHORT TERM...THE FA IS BETWEEN SYSTEMS FOR ANOTHER DAY WITH THE
LARGE HIGH OVER CANADA AND THE AREA OF LOW PRESSURE OVER THE
EASTERN GREAT LAKES. A TIGHT PRESSURE GRADIENT OVER THE EASTERN
HALF OF THE FA IS CREATING GUSTY NE WINDS. MEANWHILE...A SFC TROF
WAS LOCATED JUST TO THE W OF THE FA IN NW MN AT 07Z. THE TROF IS
EXPECTED TO WASH OUT TODAY WHILE A SFC RIDGE AXIS IS FORECAST TO
BEGIN AFFECTING THE NORTHERN TIER OF THE FA. AMONGST THESE
FEATURES ARE EMBEDDED PIECES OF SHORT WAVE ENERGY ROTATING FROM E
TO W THROUGH THE FA WHILE AN UPPER LEVEL TROF CURRENTLY IN THE
DAKOTAS MOVES EWD. WILL SEE SOME FLURRIES THIS MORNING OVER NW WI
IN RESPONSE TO THE EMBEDDED ENERGY. SOME LAKE ENHANCED SNOW
SHOWERS MAY AFFECT THE SOUTH SHORE THIS MORNING WITH THE NE FLOW
OVER THE LAKE AND WEAK CAA. THE SNOW SHOWERS SHOULD DISSIPATE
AROUND NOON WHEN DRIER AIR AND LOW LEVEL WAA IN THE 1000-850MB
LAYER OVERTAKE THE LES MECHANISMS.
THE RIDGING BUILDS OVER THE REST OF THE FA TODAY AND PERSISTS
THROUGH FRIDAY. EVEN THOUGH A WEAK UPPER TROF MOVES ACROSS THE FA
FRIDAY...THE ATMOSPHERE IS VERY DRY AND NO PCPN IS EXPECTED.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY.
A RIDGE OF HIGH PRESSURE WILL EXTEND SOUTH OVER THE NORTHLAND FROM
HIGH PRESSURE OVER HUDSON BAY FRIDAY NIGHT...SHIFTING EAST SATURDAY.
A SHORTWAVE ALOFT WILL MOVE THROUGH THE AREA DURING THE SAME
PERIOD...AND BRING A CHANCE FOR SOME LIGHT SNOW SATURDAY INTO
SATURDAY NIGHT. ANY ACCUMULATION LOOKS TO BE QUITE LIGHT AT THIS
TIME. THE LOW LEVEL FLOW WILL BE NORTH TO NORTHEAST FRIDAY
NIGHT/SATURDAY WITH 850MB TEMPS AROUND -10C TO -12C. THIS WOULD
SUPPORT SOME LES...HOWEVER...AIRMASS IS EXPECTED TO BE VERY DRY AND
WE DID NOT BRING IN ANY LES FRIDAY NIGHT/SATURDAY AT THIS TIME.
THE LOW LEVEL FLOW WILL BE EAST/NORTHEAST SUNDAY INTO MONDAY...WITH
850MB TEMPS AROUND -12C. WE AGAIN DID NOT ADD/INCREASE POPS FOR LES
AT THIS TIME AS THE AIR MASS REMAINS QUITE DRY. HOWEVER...A STRONGER
WAVE AND LOW PRESSURE SYSTEM MAY BRING SOME LIGHT SNOW MONDAY INTO
TUESDAY. AT THIS TIME...BOTH THE GFS AND ECMWF TAKE THE LOW WELL TO
OUR SOUTH...SO THE SIGNIFICANT PRECIP WILL OCCUR WELL SOUTH OF OUR
CWA. ADDED MOISTURE FROM THIS SYSTEM COULD ENHANCE SOME LES...MAINLY
ALONG THE SOUTH SHORE MONDAY NIGHT/TUESDAY...AND WE MAY HAVE TO
INCREASE SNOW CHANCES WITH LATER FORECASTS.
AN UPPER RIDGE WILL BUILD OVER THE REGION...WITH THE SURFACE RIDGE
RE-ESTABLISHING ITSELF MID WEEK...PROVIDING DRY CONDITIONS.
HIGHS THROUGH THE PERIOD WILL BE AROUND NORMAL...TO A FEW DEGREES
ABOVE AT TIMES. FRIDAY NIGHT LOOKS TO BE THE COLDEST
NIGHT...ESPECIALLY ACROSS FAR NORTHERN MINNESOTA WHERE TEMPS COULD
BE SEVERAL DEGREES BELOW ZERO.
&&
.POINT TEMPS/POPS...
DLH 27 13 24 5 / 10 0 0 10
INL 26 2 25 -5 / 10 0 0 0
BRD 29 13 29 5 / 10 0 0 0
HYR 29 12 28 1 / 10 0 0 10
ASX 27 15 25 9 / 20 0 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...STEWART
LONG TERM....TENTINGER
AREA FORECAST DISCUSSION
NWS DULUTH MN
554 AM CST THU FEB 28 2013
.AVIATION...12Z TAFS
MVFR CEILINGS COVERED THE NORTHLAND THIS MORNING...AND WILL SLOWLY
ERODE FROM THE NORTH TODAY. WE DELAYED THE CLEARING...AS SATELLITE
AND THE LATEST RAP BOTH SUGGEST CLEARING WILL TAKE LONGER. THERE
MAY BE SOME LIGHT SNOW OR FLURRIES IN SPOTS AS WELL...MAINLY OVER
NORTHWEST WISCONSIN.
&&
.PREV DISCUSSION... /ISSUED 240 AM CST THU FEB 28 2013/
SHORT TERM...THE FA IS BETWEEN SYSTEMS FOR ANOTHER DAY WITH THE
LARGE HIGH OVER CANADA AND THE AREA OF LOW PRESSURE OVER THE
EASTERN GREAT LAKES. A TIGHT PRESSURE GRADIENT OVER THE EASTERN
HALF OF THE FA IS CREATING GUSTY NE WINDS. MEANWHILE...A SFC TROF
WAS LOCATED JUST TO THE W OF THE FA IN NW MN AT 07Z. THE TROF IS
EXPECTED TO WASH OUT TODAY WHILE A SFC RIDGE AXIS IS FORECAST TO
BEGIN AFFECTING THE NORTHERN TIER OF THE FA. AMONGST THESE
FEATURES ARE EMBEDDED PIECES OF SHORT WAVE ENERGY ROTATING FROM E
TO W THROUGH THE FA WHILE AN UPPER LEVEL TROF CURRENTLY IN THE
DAKOTAS MOVES EWD. WILL SEE SOME FLURRIES THIS MORNING OVER NW WI
IN RESPONSE TO THE EMBEDDED ENERGY. SOME LAKE ENHANCED SNOW
SHOWERS MAY AFFECT THE SOUTH SHORE THIS MORNING WITH THE NE FLOW
OVER THE LAKE AND WEAK CAA. THE SNOW SHOWERS SHOULD DISSIPATE
AROUND NOON WHEN DRIER AIR AND LOW LEVEL WAA IN THE 1000-850MB
LAYER OVERTAKE THE LES MECHANISMS.
THE RIDGING BUILDS OVER THE REST OF THE FA TODAY AND PERSISTS
THROUGH FRIDAY. EVEN THOUGH A WEAK UPPER TROF MOVES ACROSS THE FA
FRIDAY...THE ATMOSPHERE IS VERY DRY AND NO PCPN IS EXPECTED.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY.
A RIDGE OF HIGH PRESSURE WILL EXTEND SOUTH OVER THE NORTHLAND FROM
HIGH PRESSURE OVER HUDSON BAY FRIDAY NIGHT...SHIFTING EAST SATURDAY.
A SHORTWAVE ALOFT WILL MOVE THROUGH THE AREA DURING THE SAME
PERIOD...AND BRING A CHANCE FOR SOME LIGHT SNOW SATURDAY INTO
SATURDAY NIGHT. ANY ACCUMULATION LOOKS TO BE QUITE LIGHT AT THIS
TIME. THE LOW LEVEL FLOW WILL BE NORTH TO NORTHEAST FRIDAY
NIGHT/SATURDAY WITH 850MB TEMPS AROUND -10C TO -12C. THIS WOULD
SUPPORT SOME LES...HOWEVER...AIRMASS IS EXPECTED TO BE VERY DRY AND
WE DID NOT BRING IN ANY LES FRIDAY NIGHT/SATURDAY AT THIS TIME.
THE LOW LEVEL FLOW WILL BE EAST/NORTHEAST SUNDAY INTO MONDAY...WITH
850MB TEMPS AROUND -12C. WE AGAIN DID NOT ADD/INCREASE POPS FOR LES
AT THIS TIME AS THE AIR MASS REMAINS QUITE DRY. HOWEVER...A STRONGER
WAVE AND LOW PRESSURE SYSTEM MAY BRING SOME LIGHT SNOW MONDAY INTO
TUESDAY. AT THIS TIME...BOTH THE GFS AND ECMWF TAKE THE LOW WELL TO
OUR SOUTH...SO THE SIGNIFICANT PRECIP WILL OCCUR WELL SOUTH OF OUR
CWA. ADDED MOISTURE FROM THIS SYSTEM COULD ENHANCE SOME LES...MAINLY
ALONG THE SOUTH SHORE MONDAY NIGHT/TUESDAY...AND WE MAY HAVE TO
INCREASE SNOW CHANCES WITH LATER FORECASTS.
AN UPPER RIDGE WILL BUILD OVER THE REGION...WITH THE SURFACE RIDGE
RE-ESTABLISHING ITSELF MID WEEK...PROVIDING DRY CONDITIONS.
HIGHS THROUGH THE PERIOD WILL BE AROUND NORMAL...TO A FEW DEGREES
ABOVE AT TIMES. FRIDAY NIGHT LOOKS TO BE THE COLDEST
NIGHT...ESPECIALLY ACROSS FAR NORTHERN MINNESOTA WHERE TEMPS COULD
BE SEVERAL DEGREES BELOW ZERO.
&&
.POINT TEMPS/POPS...
DLH 27 13 24 5 / 10 0 0 10
INL 26 2 25 -5 / 10 0 0 0
BRD 29 13 29 5 / 10 0 0 0
HYR 29 12 28 1 / 10 0 0 10
ASX 27 15 25 9 / 20 0 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...GSF
LONG TERM....MELDE
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
704 AM CST THU FEB 28 2013
.UPDATE...
ISSUED AT 653 AM CST THU FEB 28 2013
FORECAST REMAINS ON TRACK...NO CHANGES PLANNED AT THIS TIME.
WATCHING AN AREA OF STRATUS THAT HAS SLOWLY ADVANCED TOWARD KLBF.
NEAR TERM SOLUTIONS ARE SPLIT ON WHETHER THE STRATUS WILL CONTINUE
TO ADVANCE AND EVENTUALLY COVER THE SKIES ABOVE LBF. THE GUIDANCE
ALSO IS SPLIT ON THE EVENTUAL BREAKUP OF THE CLOUD DECK...WHICH
WOULD BE OF SIGNIFICANCE TO TEMPERATURES THIS MORNING AND
AFTERNOON. WILL MAINTAIN THE IDEA THAT THE STRATUS WILL REMAIN
GENERALLY EAST OF HIGHWAY 83 THROUGH MORNING...THEN BREAK INTO THE
AFTERNOON.
&&
.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 305 AM CST THU FEB 28 2013
THROUGH 12Z FRIDAY...BROAD AREA OF FRONTOGENESIS REMAINS FIXED
ACROSS NORTH CENTRAL NEBRASKA EARLY THIS MORNING WITH PROGRESSIVE
NORTHWESTERLY FLOW ALOFT USHERING IN A STEADY FEED OF MOISTURE.
STRATUS HAS BACKED WEST THIS MORNING...AS KTIF...KVTN AND POINTS
EAST ARE NOW REPORTING OVC012 OR LOWER. NEAR TERM SOLUTIONS SEEM TO
HAVE A GOOD HANDLE AT THIS POINT WITH THE STRATUS...HOWEVER THE 06Z
RAP RUN SEEMS TO BE A BIT TOO AMBITIOUS WITH THE WESTERN EXTENT OF
THE LOWER CEILINGS...WHEREAS THE 00Z NAM IS SLIGHTLY EAST. FELT THAT
A BLEND OF THE TWO BEST REPRESENTS THE CURRENT CONDITIONS...AND THUS
WILL EMPLOY THE BLEND THROUGH MIDDAY TODAY. WITH THIS
BLEND...STRATUS IS INDICATED TO REMAIN ACROSS MUCH OF NORTH CENTRAL
NEBRASKA AND THE EASTERN SANDHILLS FOR MUCH OF THE DAY. BECAUSE OF
THE CLOUD COVER...HIGH TEMPERATURES MAY ONCE AGAIN STRUGGLE TO REACH
0C EAST OF AN AINSWORTH TO BARTLETT LINE. WEST...ACROSS THE SAND
HILLS AND EASTERN PANHANDLE NEBRASKA...WAA IN THE LOW TO MID LEVELS
AND CLEARING SHOULD PROVIDE FOR TEMPERATURES ABOVE 40F.
FOR THIS EVENING AND OVERNIGHT...INHERITED FORECAST INDICATED THE
POTENTIAL OF --SN ACROSS NORTHERN PORTIONS OF THE CWA. THERE IS A
WEAK UPPER LEVEL SHORTWAVE PROGGED TO PASS THROUGH NORTHWESTERLY
FLOW THAT WILL INCREASE LIFT AND PROVIDE FOR A BRIEF PERIOD OF
SATURATION WITHIN THE DENDRITIC LAYER. LIFT IS WEAK WITH THIS
WAVE...AND DEEP MOISTURE IS LACKING...SO GOING WITH THE
LIGHT/NON-MEASURABLE PRECIPITATION SEEMS THE BEST WAY TO HANDLE THIS
AT THIS POINT IN TIME.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 305 AM CST THU FEB 28 2013
AN UPPER LEVEL DISTURBANCE WILL DIVE SOUTHEAST ACROSS THE AREA
FRIDAY MORNING. SOME VERY WEAK LIFT AND A RATHER MOIST DENDRITIC
LAYER COULD YIELD A FEW FLURRIES BEFORE NOON...OTHERWISE CLOUDS
SHOULD DECREASE DURING THE AFTERNOON AS THE SYSTEM CONTINUES MOVING
SOUTHEAST AWAY FROM THE AREA. AT THE SURFACE...A STATIONARY FRONT
WILL REMAIN ANCHORED FROM NORTH TO SOUTH ACROSS WESTERN NEBRASKA.
THIS FRONT WILL PUSH EAST INTO CENTRAL NEBRASKA SATURDAY...AND
EASTERN NEBRASKA BY SUNDAY. WESTERLY DOWNSLOPE WINDS TO THE WEST OF
THE FRONT WILL BRING 50 DEGREE HIGHS TO WESTERN NEBRASKA
SATURDAY...SPREADING INTO CENTRAL NEBRASKA BY SUNDAY. A 60 DEGREE
READING OR TWO CANNOT BE RULED OUT BY SUNDAY ACROSS FAR SOUTHWEST
NEBRASKA...AS SNOWPACK WILL BE DWINDLING BY THIS TIME.
MONDAY INTO TUESDAY STILL LOOKS INTERESTING. ALL MODELS DROP A
COMPACT CLOSED LOW SOUTHEAST ACROSS THE CENTRAL AND NORTHERN PLAINS.
MODELS HAVE BEEN STRUGGLING WITH THE TRACK OF THE SYSTEM...BUT THE
LATEST 00Z SUITE ARE ACTUALLY ALL FAIRLY CLOSE TOGETHER...AND TRACK
THE CENTER OF THE SYSTEM SOUTHEAST ACROSS NORTHERN NEBRASKA. THE
ECMWF IS FARTHEST SOUTH WITH A TRACK FROM CHADRON TO FALLS
CITY...AND THE GFS IS JUST NORTH OF THIS TRACK ALONG THE NEB/SD
BORDER. MOST OF THE PRECIPITATION WILL FALL TO THE NORTH OF THE
TRACK...SO THE ECMWF SOLUTION WOULD BRING THE HIGHEST POTENTIAL
FOR SOME ACCUMULATING SNOW TO NORTHERN NEBRASKA. ANOTHER THING TO
WATCH WITH THIS SYSTEM IS THE WIND POTENTIAL. THE GFS REALLY
CRANKS UP THE 850 MB WIND SPEEDS /NEAR 55 KTS/ ON THE BACKSIDE OF
THE LOW ACROSS WESTERN NEBRASKA...THE ECMWF IS LESS IMPRESSIVE.
BOTTOM LINE HERE IS THAT WE WILL CONTINUE TO MONITOR THE LATEST
TREND IN THE MODELS. A SHIFT FARTHER SOUTH WOULD MEAN LESS WIND
BUT MORE SNOWFALL POTENTIAL...AND A SHIFT NORTH WOULD MEAN VERY
LITTLE PRECIPITATION BUT MORE WIND.
BY MID WEEK A WARMING TREND WILL DEVELOP ONCE AGAIN AHEAD OF A
DEVELOPING LONG WAVE TROUGH ACROSS THE WESTERN CONUS. SOUTHERLY
WINDS WILL BEGIN TO TRANSPORT MOISTURE NORTHWARD BY WEEKS
END...POSSIBLE LEADING TO PRECIPITATION BY THE WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 537 AM CST THU FEB 28 2013
MVFR CEILINGS ARE FORECAST TO PERSIST AT KVTN UNTIL 18Z/28TH. WHILE
THERE COULD BE TIMES WHEN CEILINGS GO VFR...THE RAP MODEL SEEMS TO BE
HANDLING THE AREAS OF STRATUS BEST...KEEPING KVTN WITHIN THE LOWER
CEILINGS INTO EARLY AFTERNOON. KLBF IS EXPECTED TO CONTINUE TO
REMAIN IN VFR CONDITIONS THROUGH THE FORECAST PERIOD...HOWEVER THE
STRATUS IS JUST TO THE EAST OF THE TERMINAL...SO WILL NEED TO BE
WATCHED CLOSELY AS NEAR TERM SOLUTIONS ARE SPLIT ON WHETHER THE
LOWER CEILINGS MAKE IT AS FAR SOUTHWEST AS KLBF. SHORT-FUSED
AMENDMENTS MAY BE NEEDED AT KLBF AS FORECAST CONFIDENCE IS LOW TO
MEDIUM AT THIS TIME. OTHERWISE SURFACE WINDS SHOULD REMAIN LIGHT
AND FROM THE NORTHWEST AT OR BELOW 10KT FOR BOTH FORECAST SITES
THROUGH THE PERIOD.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JACOBS
SHORT TERM...JACOBS
LONG TERM...TAYLOR
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
538 AM CST THU FEB 28 2013
.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 305 AM CST THU FEB 28 2013
THROUGH 12Z FRIDAY...BROAD AREA OF FRONTOGENESIS REMAINS FIXED
ACROSS NORTH CENTRAL NEBRASKA EARLY THIS MORNING WITH PROGRESSIVE
NORTHWESTERLY FLOW ALOFT USHERING IN A STEADY FEED OF MOISTURE.
STRATUS HAS BACKED WEST THIS MORNING...AS KTIF...KVTN AND POINTS
EAST ARE NOW REPORTING OVC012 OR LOWER. NEAR TERM SOLUTIONS SEEM TO
HAVE A GOOD HANDLE AT THIS POINT WITH THE STRATUS...HOWEVER THE 06Z
RAP RUN SEEMS TO BE A BIT TOO AMBITIOUS WITH THE WESTERN EXTENT OF
THE LOWER CEILINGS...WHEREAS THE 00Z NAM IS SLIGHTLY EAST. FELT THAT
A BLEND OF THE TWO BEST REPRESENTS THE CURRENT CONDITIONS...AND THUS
WILL EMPLOY THE BLEND THROUGH MIDDAY TODAY. WITH THIS
BLEND...STRATUS IS INDICATED TO REMAIN ACROSS MUCH OF NORTH CENTRAL
NEBRASKA AND THE EASTERN SANDHILLS FOR MUCH OF THE DAY. BECAUSE OF
THE CLOUD COVER...HIGH TEMPERATURES MAY ONCE AGAIN STRUGGLE TO REACH
0C EAST OF AN AINSWORTH TO BARTLETT LINE. WEST...ACROSS THE SAND
HILLS AND EASTERN PANHANDLE NEBRASKA...WAA IN THE LOW TO MID LEVELS
AND CLEARING SHOULD PROVIDE FOR TEMPERATURES ABOVE 40F.
FOR THIS EVENING AND OVERNIGHT...INHERITED FORECAST INDICATED THE
POTENTIAL OF --SN ACROSS NORTHERN PORTIONS OF THE CWA. THERE IS A
WEAK UPPER LEVEL SHORTWAVE PROGGED TO PASS THROUGH NORTHWESTERLY
FLOW THAT WILL INCREASE LIFT AND PROVIDE FOR A BRIEF PERIOD OF
SATURATION WITHIN THE DENDRITIC LAYER. LIFT IS WEAK WITH THIS
WAVE...AND DEEP MOISTURE IS LACKING...SO GOING WITH THE
LIGHT/NON-MEASURABLE PRECIPITATION SEEMS THE BEST WAY TO HANDLE THIS
AT THIS POINT IN TIME.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 305 AM CST THU FEB 28 2013
AN UPPER LEVEL DISTURBANCE WILL DIVE SOUTHEAST ACROSS THE AREA
FRIDAY MORNING. SOME VERY WEAK LIFT AND A RATHER MOIST DENDRITIC
LAYER COULD YIELD A FEW FLURRIES BEFORE NOON...OTHERWISE CLOUDS
SHOULD DECREASE DURING THE AFTERNOON AS THE SYSTEM CONTINUES MOVING
SOUTHEAST AWAY FROM THE AREA. AT THE SURFACE...A STATIONARY FRONT
WILL REMAIN ANCHORED FROM NORTH TO SOUTH ACROSS WESTERN NEBRASKA.
THIS FRONT WILL PUSH EAST INTO CENTRAL NEBRASKA SATURDAY...AND
EASTERN NEBRASKA BY SUNDAY. WESTERLY DOWNSLOPE WINDS TO THE WEST OF
THE FRONT WILL BRING 50 DEGREE HIGHS TO WESTERN NEBRASKA
SATURDAY...SPREADING INTO CENTRAL NEBRASKA BY SUNDAY. A 60 DEGREE
READING OR TWO CANNOT BE RULED OUT BY SUNDAY ACROSS FAR SOUTHWEST
NEBRASKA...AS SNOWPACK WILL BE DWINDLING BY THIS TIME.
MONDAY INTO TUESDAY STILL LOOKS INTERESTING. ALL MODELS DROP A
COMPACT CLOSED LOW SOUTHEAST ACROSS THE CENTRAL AND NORTHERN PLAINS.
MODELS HAVE BEEN STRUGGLING WITH THE TRACK OF THE SYSTEM...BUT THE
LATEST 00Z SUITE ARE ACTUALLY ALL FAIRLY CLOSE TOGETHER...AND TRACK
THE CENTER OF THE SYSTEM SOUTHEAST ACROSS NORTHERN NEBRASKA. THE
ECMWF IS FARTHEST SOUTH WITH A TRACK FROM CHADRON TO FALLS
CITY...AND THE GFS IS JUST NORTH OF THIS TRACK ALONG THE NEB/SD
BORDER. MOST OF THE PRECIPITATION WILL FALL TO THE NORTH OF THE
TRACK...SO THE ECMWF SOLUTION WOULD BRING THE HIGHEST POTENTIAL
FOR SOME ACCUMULATING SNOW TO NORTHERN NEBRASKA. ANOTHER THING TO
WATCH WITH THIS SYSTEM IS THE WIND POTENTIAL. THE GFS REALLY
CRANKS UP THE 850 MB WIND SPEEDS /NEAR 55 KTS/ ON THE BACKSIDE OF
THE LOW ACROSS WESTERN NEBRASKA...THE ECMWF IS LESS IMPRESSIVE.
BOTTOM LINE HERE IS THAT WE WILL CONTINUE TO MONITOR THE LATEST
TREND IN THE MODELS. A SHIFT FARTHER SOUTH WOULD MEAN LESS WIND
BUT MORE SNOWFALL POTENTIAL...AND A SHIFT NORTH WOULD MEAN VERY
LITTLE PRECIPITATION BUT MORE WIND.
BY MID WEEK A WARMING TREND WILL DEVELOP ONCE AGAIN AHEAD OF A
DEVELOPING LONG WAVE TROUGH ACROSS THE WESTERN CONUS. SOUTHERLY
WINDS WILL BEGIN TO TRANSPORT MOISTURE NORTHWARD BY WEEKS
END...POSSIBLE LEADING TO PRECIPITATION BY THE WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 537 AM CST THU FEB 28 2013
MVFR CEILINGS ARE FORECAST TO PERSIST AT KVTN UNTIL 18Z/28TH. WHILE
THERE COULD BE TIMES WHEN CEILINGS GO VFR...THE RAP MODEL SEEMS TO BE
HANDLING THE AREAS OF STRATUS BEST...KEEPING KVTN WITHIN THE LOWER
CEILINGS INTO EARLY AFTERNOON. KLBF IS EXPECTED TO CONTINUE TO
REMAIN IN VFR CONDITIONS THROUGH THE FORECAST PERIOD...HOWEVER THE
STRATUS IS JUST TO THE EAST OF THE TERMINAL...SO WILL NEED TO BE
WATCHED CLOSELY AS NEAR TERM SOLUTIONS ARE SPLIT ON WHETHER THE
LOWER CEILINGS MAKE IT AS FAR SOUTHWEST AS KLBF. SHORT-FUSED
AMENDMENTS MAY BE NEEDED AT KLBF AS FORECAST CONFIDENCE IS LOW TO
MEDIUM AT THIS TIME. OTHERWISE SURFACE WINDS SHOULD REMAIN LIGHT
AND FROM THE NORTHWEST AT OR BELOW 10KT FOR BOTH FORECAST SITES
THROUGH THE PERIOD.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JACOBS
LONG TERM...TAYLOR
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
349 PM MST THU FEB 28 2013
.SHORT TERM...MOISTURE CONTINUES TO INCREASE ACROSS MOUNTAINS AS
DISTURBANCE BEGINS TO MOVE INTO WESTERN COLORADO. MODERATE
NORTHWEST FLOW ALOFT PROVIDING DECENT OROGRAPHICS WITH OROGRAPHICS
AROUND 6 C/KM. MOUNTAIN WEB CAMS SHOWING SNOW SHOWERS BECOMING
MORE WIDESPREAD...MAINLY ALONG CONTINENTAL DIVIDE OF SUMMIT AND
GRAND COUNTIES AS WELL AS PARK AND GORE RANGES OF WESTERN JACKSON
COUNTY. SO FAR... ACCUMULATIONS MINIMAL BASED ON LATEST SNOTEL
DATA. WINDS HAVE BEEN GUSTY OVER THE HIGHER MOUNTAINS AND ALONG
FOOTHILLS AS WELL AS ACROSS SOUTH PARK. DISTURBANCE TO MOVE ACROSS
MOUNTAINS AND PLAINS THROUGH THE EVENING. LATEST RAP AND NAM QG
VERTICAL VELOCITY PROGS STILL INDICATING ASCENT TO BE MINIMAL...SO
MOUNTAIN SNOWFALL TO BE MAINLY OROGRAPHICALLY DRIVEN WITH SOME
HELP WITH INSTABILITY. ACCUMULATIONS OF 1 TO 4 INCHES STILL
LOOKING ON TRACK THOUGH SOME LOCATIONS ALONG THE FAVORED WEST AND
NORTHWEST ASPECTS COULD RECEIVE A COUPLE EXTRA INCHES. NORTHWEST
FLOW TO PROVIDE DOWNSLOPE IN AND NEAR FOOTHILLS SO SNOW SHOWERS
THERE WILL BE LIMITED. BUT THERE WILL BE SOME WIND GUSTS TO 50 MPH
DUE TO THE DOWNSLOPE. ACROSS PLAINS... SOUTHEAST WINDS DEVELOPED
IN THE DENVER AREA DUE TO WEAK ANTICYCLONE OVER SOUTHERN WELD
COUNTY. LATEST MODELS SHOWING THIS ANTICYCLONE SHIFTING EAST OF
THE DENVER AREA DURING THE EVENING AS DOWNSLOPE OFF FOOTHILLS
BEGINS TO DOMINATE FRONT RANGE. STILL THINKING THIS DOWNSLOPE FLOW
WILL LIMIT SNOW CHANCES ALONG URBAN CORRIDOR. MODELS STILL SHOWING
BEST CHANCE FOR SHOWERS TO BE EAST AND SOUTH OF DENVER...PAINTING
SOME LIGHT QPF AND SNOW ACCUMULATIONS. WILL UP THE POPS TO THE
CHANCE CATEGORY IN THIS AREA...KEEPING REST OF THE POPS AS IS.
LATEST CROSS SECTIONS INDICATE A GRADUAL DECREASE IN MOISTURE
AFTER MIDNIGHT. STILL GOOD OROGRAPHICS FOR CONTINUED MOUNTAIN SNOW
SHOWERS. CLOUD COVER AND WIND TO HELP MODERATE OVERNIGHT
TEMPERATURES. ON FRIDAY...FLOW ALOFT BECOMES A BIT MORE NORTHERLY
AS TROUGH MOVES INTO CENTRAL PLAINS. MOISTURE OVER MOUNTAINS
CONTINUES TO DRY OUT. OROGRAPHICS STILL FAVORABLE FOR MOUNTAIN
SNOW SHOWERS...THOUGH INCREASING STABILITY AND LACK OF LIFT WILL
LIMIT COVERAGE. PERHAPS ANOTHER INCH OR SO OF ACCUMULATION. ACROSS
PLAINS...SOME MID AND HIGH LEVEL CLOUDS TO PREVAIL. AIRMASS TO
WARM SLIGHTLY...SHOULD ALLOW TEMPERATURES TO WARM INTO THE 40S
ACROSS THE PLAINS...THOUGH SNOW COVER COULD KEEP TEMPERATURES IN
THE 30S. WINDS TO BE A BIT GUSTY ACROSS HIGHER RIDGES AND FAR
EASTERN PLAINS.
.LONG TERM...THE CWA WILL BE UNDER FAIRLY STRONG NORTHERLY FLOW
ALOFT BY FRIDAY EVENING AS A VERY FAST MOVING SHORT WAVE TROUGH
WHICH CLIPS THE HIGH PLAINS STATES EARLY FRIDAY MOVES OUT OF THE
AREA. THE 12Z NAM INDICATES A SECOND BUT VERY MINOR DISTURBANCE IN
THE NORTHERLY FLOW WHICH PROVIDES ADDITIONAL BUT SCANT MOISTURE TO
THE HIGH COUNTRY ALONG WITH ANOTHER PUSH OF STRONG NORTHWEST WINDS
ACROSS THE NORTHEAST PLAINS LATE FRIDAY INTO EARLY SATURDAY. DRY
DOWNSLOPE LOOKS TO BE THE RULE ONCE AGAIN WITH NO POPS EXPECETED
AT LOWER ELEVATIONS. IN THE HIGH COUNTRY...CROSS SECTIONS CONTINUE
TO SHOW SHALLOW MOISTURE BEING HELD AGAINST THE DIVIDE WITH
OROGRAPHICS DOING THE ONLY LIFTING FOR ANY SNOW SHOWERS. GFS-QG
FIELDS INDICATE NEUTRAL TO SLIGHT DOWNWARD MOTION FRIDAY EVE
THROUGH LATE SATURDAY AND SEE NO REASON TO BUMP THE POPS OVER THE
ISOLD SNOW SHOWERS CURRENTLY IN THE ZFP. BY MIDDAY/EVE SATURDAY
THE AMPLIFIED RIDGE OF HIGH PRESSURE WITH AN AXIS LOCATED OVER THE
EASTERN EDGE OF THE GREAT BASIN IS ALREADY WEAKENING OUT AHEAD OF
THE NEXT DISTURBANCE EXPECTED FOR THE NORTHERN COLO EARLY SUNDAY.
AS THE WEAKENING RIDGE MOVES OUT OVER THE CENTRAL US...TIGHT
PACKING IN THE MID/UPPER LEVEL HEIGHT FIELDS PROVIDES FOR SOME
BRIEF BUT STRONG WESTERLY FLOW ACROSS THE STATE ON SUNDAY.
SANGSTER HIGH WIND MODEL INDICATES POTENTIAL HIGH WIND CRITERIA
BEING MET FOR THE SUNDAY AFT/EVE. WILL BUMP UP WIND GRIDS FOR THIS
NOTIFICATION AND SHD BE WATCHED IN LATER RUNS. AFTER THIS
INFLECTION POINT IN THE FLOW ALOFT...LATEST GFS/CMC TRAJECTORY
WITH THIS NEXT FAST MOVING WAVE TAKES UPPER LOW OVER WESTERN MT
SOUTHEASTWARD OVER THE BLACK HILLS REGION OF SD AND INTO EAST CENT
NE BY MONDAY NIGHT. THIS WILL DO MUCH LIKE THE PREVIOUS WAVES
GIVING A BRIEF SHOT OF LIGHT SNOW TO THE NORTHERN AND CENT MTNS
WHILE PRODUCING DRY NORTHWEST DOWNSLOPE FLOW EAST OF THE DIVIDE.
ECM IS SLOWER WITH THE FEATURE BUT DRYER AND MORE NORTHERLY.
HOWEVER...HAVE ADJUSTED POP GRIDS AROUND THIS SUNDAY INTO EARLY
MONDAY TIME FRAME FOR THE MTN LOCATIONS FOR A LONGER PERIOD OF
LIGHT SNOW ASSOC WITH TROUGH.
LOOKING TOWARD THE TUESDAY THROUGH THURSDAY PERIOD...A WARM
STABLE RIDGE OF HIGH PRESSURE WILL CONTINUE TO DEVELOP OVER THE
WESTERN US WHILE MAXIMIZING IN THE TUESDAY EVENING TO EARLY
WEDNESDAY TIMEFRAME. WILL EXPECT TUE TO REMAIN COOL AND BREEZY IN
THE MORNING POST TROUGH THEN GOOD WARMING INTO TUESDAY AFTN AND THE
DAYS AHEAD. THIS RIDGE WILL LIKELY TAKE DAYTIME HIGHS WELL ABOVE
SEASONAL NORMALS AT LOWER ELEVATIONS FOR BOTH WED AND THURS AS
WARMER SOUTHWESTERLY FLOW ALOFT PREVAILS BOTH DAYS IN ADVANCE OF THE
NEXT LARGER AND COLDER WAVE BEYOND THURSDAY.
&&
.AVIATION...WEAK ANTICYCLONE NORTH OF DENVER...WITH SOUTHEAST
WINDS AT KDEN WHILE DOWNSLOPE WESTERLIES PREVAILING AT KBJC AND
KAPA. ANTICYCLONE EXPECTED TO MOVE SOUTHEAST OF DENVER DURING THE
EVENING...WITH WINDS SHIFTING TO THE NORTHWEST AT KDEN. CEILINGS
TO LOWER DURING THE EVENING...SHOULD REMAIN ABOVE 10000 FEET WITH
VFR CONDITIONS PREVAILING. SLIGHT CHANCE OF SNOW SHOWERS THIS
EVENING AS DISTURBANCE MOVES ACROSS. STILL THINKING THE BEST
CHANCE FOR SHOWERS WILL BE SOUTHEAST OF DENVER AS THE DOWNSLOPE
WIND SHOULD LIMIT THE SHOWERS. IF A SHOWER DOES OCCUR...IT SHOULD
BE LIGHT AND BRIEF WITH LITTLE OR NO ACCUMULATION. CEILINGS OF
AROUND 6000 FEET AGL COULD ACCOMPANY THE SHOWERS. FOR NOW WILL
LEAVE OUT OF THE TAFS. AFTER MIDNIGHT... WINDS TO SHIFT TO SOUTH
SOUTHWEST AS DRAINAGE DEVELOPS. SOUTHERLY WINDS TO PREVAIL THROUGH
THE DAY FRIDAY WITH SPEEDS LESS THAN 8 KTS. VFR TO CONTINUE.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....FREDIN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1009 AM MST THU FEB 28 2013
.UPDATE...
&&
.SHORT TERM...CURRENT FORECASTS STILL SEEM ON TRACK. MODERATE
NORTHWEST FLOW CONTINUES AS MODELS STILL INDICATING WEAK MID LEVEL
DISTURBANCE MOVING ACROSS COLORADO TODAY. SOME PRECIPITATION
CURRENTLY OVER UTAH AND IDAHO. LATEST RAP AND NAM QG PROGS
INDICATING MINIMAL ASCENT AS DISTURBANCE PASSES OVERHEAD. LAPSE
RATES FAIRLY REASONABLE ALONG WITH DECENT MOUNTAIN OROGRAPHICS FOR
SNOW SHOWERS AFTER 21Z ONCE AIRMASS MOISTENS WITH SOME
ACCUMULATIONS...MAINLY DURING THE EVENING. AMOUNTS UP TO 4 INCHES
STILL SEEMS REASONABLE. ACROSS PLAINS...DOWNSLOPE FLOW TO KEEP
THINGS DRY THOUGH 00Z. STILL SOME QUESTION THIS EVENING ON THE
POTENTIAL FOR WEAK UPSLOPE FLOW ALONG FRONT RANGE WHICH COULD
INCREASE THE SNOW CHANCES. STILL LOOKING LIKE THE DOWNSLOPE WILL
PREVAIL...AND WILL MAINTAIN THE CURRENT POPS. BETTER CHANCE FOR
SHOWERS STILL EAST AND SOUTHEAST OF DENVER AWAY FROM THE
DOWNSLOPE AND IS WHERE THE LATEST MODELS ARE SHOWING THE QPF AND
LIGHT SNOW AMOUNTS. DOES NOT APPEAR TO BE A DECENT WEATHER
PRODUCER FOR THE PLAINS GIVEN THE MINIMAL ASCENT AND WILL MAINTAIN
THE SLIGHT POPS FOR THE EVENING. WILL CONTINUE TO MONITOR THE
DEVELOPMENT OF THIS SYSTEM TO SEE OF HIGHER POPS WILL BE NEEDED.
.AVIATION...CURRENT TAF TRENDS STILL SEEM ON TRACK. MODELS
CONTINUE TO HINT AT THE DEVELOPMENT OF A WEAK ANTICYCLONE THIS
AFTERNOON WHICH COULD SHIFT WINDS TO THE NORTHEAST OR EAST AT DEN
AND APA. FOR NOW WILL MAINTAIN THE NORTHWEST DIRECTION. CLOUDS TO
GRADUALLY INCREASE THIS AFTERNOON WITH CEILINGS AROUND 10000 FEET
BY 00Z. SIGHT CHANCE FOR A FEW SHOWERS THIS EVENING IN THE DENVER
AREA...MAINLY EAST AND SOUTHEAST OF THE AIRPORTS. IT STILL LOOKS
LIKE THE DOWNSLOPE WINDS WILL PREVAIL...LIMITING CHANCE FOR
SHOWERS AT THE AIRPORTS. THERE IS A SLIGHT CHANCE OF CEILINGS
AROUND 5000 FEET AGL WITH THE SHOWERS...WILL HOLD OFF IN INCLUDING
AT THIS TIME. IF SHOWERS DO AFFECT THE AIRPORT...THEY SHOULD BE
LIGHT AND BRIEF WITH LITTLE OR NO ACCUMULATION.
&&
.PREV DISCUSSION... /ISSUED 409 AM MST THU FEB 28 2013/
SHORT TERM...NORTH-NORTHWESTERLY FLOW ALOFT WILL BEGIN TO VEER TO
THE NORTH BY TONIGHT AS A 110 KT JET MOVES IN FROM THE PACIFIC
NORTHWEST. MOISTURE BROUGHT IN BY THIS SYSTEM WILL BEGIN
INCREASING SNOW OVER THE MOUNTAINS THIS MORNING. THERE IS NOT MUCH
UPWARD QG VERTICAL MOTION WITH THIS SYSTEM...BUT THE WIND
DIRECTION IS OPTIMAL FOR OROGRAPHICALLY FORCED SNOW OVER THE
MOUNTAINS. EXPECT 1-4 INCHES OF SNOW OVER THE HIGHER MOUNTAINS
THROUGH THE DAY AND INTO THE NIGHT HOURS. NORTHWEST FLOW TENDS TO
DOWNSLOPE OVER THE FOOTHILLS AND ADJACENT PLAINS...BUT FURTHER
EAST WILL HAVE A BETTER CHANCE TO SEE SNOW SHOWERS. MODEL
SOUNDINGS SHOW SOME INSTABILITY OUT THERE AND SATURATED PROFILES
FURTHER EAST. SOUNDINGS CLOSER TO THE FOOTHILLS KEEP IT DRY AT
LOWER LEVELS DUE TO THE EXPECTED DOWNSLOPING. THE WILD CARD IS THE
LOW LEVEL WINDS...AS A COUPLE MODELS ARE HINTING AT AN ANTICYCLONE
SETTING UP NEAR OR NORTH OF DENVER. IF THIS OCCURS...IT MAY HELP
TO BRING IN SOME MOISTURE WITH A SLIGHT UPSLOPE FLOW. WILL NEED TO
MONITOR THESE WINDS LATE THIS AFTERNOON. GUSTY NORTHWEST WINDS
WILL ACCOMPANY THE SHOWERS OVER THE PLAINS WITH GUSTS UP TO 25
MPH. THE MOUNTAINS AND UPPER FOOTHILLS WILL SEE STRONGER
WINDS...WITH SPEEDS AROUND 15 TO 30 MPH WITH GUSTS AS HIGH AS 50
MPH. A BRIEF LOOK AT THIS PATTERN MAY LOOK LIKE WHAT OCCURRED LAST
TUESDAY...BUT WE HAVE NO WHERE NEAR THE LIFT WE HAD THAT DAY. QG
VERTICAL MOTION VALUES WERE NEAR -35 UPWARD...WHERE AS TODAY WE
ARE RIGHT AROUND 0. THE JET IS MOVING OVERHEAD HOWEVER...SO THAT
CAN ALWAYS PLAY INTO AMOUNTS. WILL INCREASE POPS OVER THE PLAINS
MAINLY ALONG AND SOUTH OF I70 AND KEEP AMOUNTS LIGHT FOR NOW. MAX
TEMPERATURES TODAY WILL BE SLIGHTLY HIGHER THAN YESTERDAY...WITH
MID TO UPPER 30S FOR THE PLAINS AND 20S FOR THE MOUNTAINS.
MOISTURE WILL BE DECREASING AFTER MIDNIGHT WITH ONLY HIGH CLOUDS
EXPECTED. THIS...ALONG WITH NORTHWEST WINDS REMAINING A BIT
GUSTY...WILL HELP MODERATE MINIMUM TEMPERATURES TONIGHT. WINDS
WILL REMAIN GUSTY OVER THE MOUNTAINS AS WELL...WITH GUSTS UP TO
50 MPH.
LONG TERM...STILL EXPECT ENOUGH MOISTURE AND GOOD OROGRAPHIC FLOW
IN THE MOUNTAINS FOR SNOW SHOWERS TO CONTINUE INTO FRIDAY. ANY
ACCUMULATION WILL BE LIMITED BY INCREASING STATIC STABILITY WITH
AMOUNTS AN INCH OR LESS. ON THE PLAINS...SOME MID/UPPER LEVEL
CLOUDS CAN BE EXPECTED ALTHOUGH SHOULD BE PLENTY OF BREAKS AS WELL
TO ALLOW A DECENT WARMUP.
FOR SATURDAY AND SUNDAY...WARMING TREND WILL CONTINUE WITH
WESTERLY FLOW ALOFT AND SIGNIFICANT MID LEVEL WARMING. 700 MB
TEMPS RISE TO NEAR 0C BY LATE SATURDAY...AND THEN NEAR 2C BY
EARLY SUNDAY. DESPITE SNOW COVER...WE ARE ENTERING MARCH AND
SUNSHINE WILL HAVE MORE EFFECT ON TEMPS. WILL STILL BE A LITTLE
CONSERVATIVE WITH HIGH TEMPS SATURDAY ESPECIALLY EAST OF DENVER
WHERE SLIGHTLY DEEPER INVERSIONS WILL EXIST. THEN EXPECT FURTHER
MODERATION SUNDAY WITH THINNING SNOW COVER AND STRONGER DOWNSLOPE
FLOW AND BETTER MIXING.
BY SUNDAY AFTERNOON...LIFT AND COLD ADVECTION FROM THE NEXT
APPROACHING DISTURBANCE SHOULD REACH THE MOUNTAINS WITH SNOW
DEVELOPING. LATEST GFS...MOST GFS ENSEMBLES...AND ECMWF ARE IN
REASONABLE AGREEMENT WITH TIMING AND LOCATION. THIS WOULD BRING
SNOW TO THE MOUNTAINS FROM SUNDAY AFTERNOON THROUGH SUNDAY
NIGHT...AND ALSO POTENTIAL FOR STRONG WINDS ACROSS THE PLAINS FROM
LATE SUNDAY NIGHT INTO MONDAY IN THIS SYSTEMS WAKE. AS A RESULT...
WE HAVE INCREASED SNOW IN THE HIGH COUNTRY AND WINDS FROM THE
FRONT RANGE DOWN ACROSS ALL OF THE PLAINS. THERE IS JUST A SLIGHT
CHANCE THE UPPER TROUGH COULD DIG A BIT MORE FOR LESS WIND AND A
CHANCE OF PRECIP ON THE PLAINS...SO WILL CONTINUE TO MONITOR THIS
SYSTEM OVER THE NEXT COUPLE DAYS.
AFTER THIS SYSTEM...A HIGH AMPLITUDE UPPER LEVEL RIDGE WILL BUILD
BACK ACROSS THE CENTRAL ROCKIES FOR TUESDAY AND WEDNESDAY. THIS
WILL BRING MORE SPRING-LIKE WEATHER WITH HIGHS PUSHING THE 60S BY
WEDNESDAY.
AVIATION...VFR CONDITIONS TO CONTINUE THIS MORNING WITH AN INCREASE
IN MID AND HIGH LEVEL CLOUDS. DRAINAGE WINDS EXPECTED TO BECOME
NORTHWEST AROUND 16Z...WITH THE POSSIBILITY OF ANOTHER WEAK
ANTICYCLONE DEVELOPING NORTH OF DENVER. THIS COULD SHIFT WINDS TO
A NORTHEAST DIRECTION. FOR NOW WILL MAINTAIN THE NORTHWEST
DIRECTION WITH SPEEDS AROUND 8 KTS...BUT MAY NEED TO SWITCH THEM
OVER TO A NORTHEAST DIRECTION DEPENDING ON HOW WELL MIXED THE
ATMOSPHERE BECOMES. CEILINGS TO GRADUALLY LOWER DURING THE
AFTERNOON...SHOULD REMAIN ABOVE 10000 FEET AGL. A FEW SNOW SHOWERS
COULD DEVELOP AFTER 00Z. AT THIS TIME IT LOOKS LIKE THE DOWNSLOPE
NORTHWEST WINDS WILL HINDER THE DEVELOPMENT AND ANY SNOW SHOWER
ACTIVITY SHOULD REMAIN EAST OF THE AIRPORTS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....BARJENBRUCH
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
253 PM CST THU FEB 28 2013
.DISCUSSION...
AN OVERALL BENIGN 7-DAY FORECAST PERIOD WITH THE EXCEPTION OF THE
MONDAY-TUESDAY TIME FRAME...IN WHICH AT LEAST PART OF THE FORECAST
AREA COULD GET CLIPPED WITH ACCUMULATING SNOWFALL.
IN THE MEANTIME...AFTERNOON WATER VAPOR IMAGERY ILLUSTRATES THE
TROUGH SPINNING OVER THE EASTERN CONUS...WHILE WEAK RIDGING IS IN
PLACE LOCALLY. LOW LEVEL MOISTURE TRAPPED BETWEEN SAID EASTERN
TROUGH AND AN AMPLIFYING WESTERN RIDGE HAS BEEN RESPONSIBLE FOR
PROLONGED LOW CLOUD COVER AND LITTLE VARIATION IN TEMPERATURES
OVER THE LAST SEVERAL DAYS. EXPECT THAT TO BE THE CASE AGAIN
TONIGHT...SO HAVE MAINTAINED A MOSTLY CLOUDY FORECAST FOR TONIGHT
AND LEANED TOWARD THE HIGHER END OF NUMERICAL GUIDANCE FOR LOW
TEMPS.
NORTHERLY FLOW REMAINS IN PLACE OVER THE FORECAST AREA THROUGH THE
WEEKEND AS THE WESTERN RIDGE BUILDS SLOWLY EASTWARD BUT IS SLOWED
BY THE BLOCKING HIGH OVER QUEBEC. HIGH TEMPERATURES FROM FRIDAY
THROUGHT THE WEEKEND WILL NOT STRAY FAR FROM THE 25 TO 35 DEGREE
RANGE /5 TO 10 DEGREES BELOW NORMAL/. THERE COULD BE A FEW
FLURRIES OR VERY LIGHT SNOW ON SATURDAY AND SATURDAY
NIGHT...MAINLY ACROSS CENTRAL MN...AS SHEARED MID LEVEL ENERGY
PASSES OVER. ACCOMPANYING MOISTURE IS NOT ABUNDANT...BUT LOOKS
SUFFICIENT TO WARRANT 20 POPS.
REGARDING THE MONDAY-TUESDAY SYSTEM...WHILE MODELS ARE STILL
FLUCTUATING FROM RUN TO RUN WITH THE TRACK...THE MN RIVER VALLEY
AND AREAS SOUTH STILL LOOK LIKE THE PRIME AREA TO SEE SNOWFALL
ACCUMULATIONS OF SEVERAL INCHES. HAVE MAINTAINED LIKELY POPS IN
FROM FAR WEST CENTRAL INTO SOUTH CENTRAL MN...WHERE IF THE 12Z ECMWF WERE
TO VERIFY...WARNING TYPE SNOWS WOULD BE SEEN.
IN THE AFTERMATH OF THE MONDAY SYSTEM...A HIGHLY AMPLIFIED RIDGE
IS FORECAST TO BUILD OVER THE CENTRAL CONUS...AS A TROUGH IS
CARVED OUT OVER THE WEST COAST. THIS WOULD TRANSLATE TO A WARMING
TREND OVER THE AREA...WITH HIGHS IN THE MID 30S TO MID 40S RANGE.
&&
.AVIATION.../18Z TAF ISSUANCE/
AREA REMAINS UNDER THE INFLUENCE OF BROAD CYCLONIC FLOW ASSOCIATED
WITH OCCLUDED LOW NOW OVER LAKE ONTARIO. EXPANSIVE MVFR CIGS IN
PLACE...AND EXPECT THEM TO REMAIN THERE THROUGH THE AFTERNOON.
CURRENTLY TRACKING A CLEARING IN THESE CIGS OVER THE ARROWHEAD
MOVING SOUTH AT ABOUT 20 KTS. ALL GUIDANCE SWEEPS THIS CLEARING
SOUTH ACROSS MN/WI THIS EVENING...WITH ALL TERMINALS EXPECTED TO
RETURN TO VFR THIS EVENING. SLOWED THE RETURN TO VFR SOME BASED ON
RAP HANDLING OF 925-850 RH...THOUGH THIS MAY BE A LITTLE SLOW.
ONLY CONCERN FOR NOT CLEARING OUT IS AT AXN...AS SFC RIDGE WILL BE
MOVING IN OVERNIGHT...WITH THE RAP INDICATING THAT THIS LOW LEVEL
MOISTURE STAYS TRAPPED UNDER AN INVERSION ASSOCIATED WITH THE
RIDGE. BY LATE FRIDAY MORNING...CU RULES FROM BOTH THE NAM/GFS
REMAIN NEGATIVE...AND DO ANTICIPATE AN MVFR CU FIELD TO DEVELOP BY
THE END OF THE TAF PERIOD.
KMSP...CIGS HAVE SETTLED IN AT 025 AND EXPECT THEM TO REMAIN THERE
UNTIL THEIR DEPARTURE. AS FOR THEIR DEPARTURE...THE NAM PUSHES THEM
OUT AROUND 4Z...WHILE THE RAP HOLDS ON TO THE LOW LEVEL MOISTURE
THROUGH 9Z. BY FRIDAY MORNING CONFIDENCE IS HIGH IN STARTING OUT
WITH VFR CONDS. WITH PLENTY OF LOW LEVEL MOISTURE HANGING
AROUND...EXPECT EXPANSIVE STRATOCU FIELD TO DEVELOP AS WE BEGIN TO
MIX TOMORROW MORNING...AS INDICATED BY THE NEGATIVE CU RULES. CIGS
WILL LIKELY START MVFR AND TREND TOWARD VFR LEVELS IN THE
AFTERNOON...BUT TO HARD TO PIN DOWN WHEN THAT MAY OCCUR AT THIS
POINT...SO KEPT THINGS SIMPLE TOWARD THE END OF THE TAF. NO OTHER
ISSUES ARE EXPECTED...WITH WINDS REMAINING IN THE 010-030 RANGE
FOR THE NEXT 30 HOURS.
/OUTLOOK FOR KMSP/
SAT...VFR. WINDS LGT AND VRB.
SUN...VFR. SE WINDS 5 KTS.
MON...CHANCE OF SN. VFR OUTSIDE OF SNOW...IFR OR LOWER WITH SN.
ESE WINDS 10-20 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
LS/MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1146 AM CST THU FEB 28 2013
.UPDATE...
18Z AVIATION DISCUSSION ADDED BELOW.
&&
.PREV DISCUSSION...
/ISSUED 558 AM CST THU FEB 28 2013/
SHORT TERM...TODAY THROUGH SATURDAY NIGHT.
AT 3 AM...THE LARGE OCCLUDED LOW WAS CENTERED OVER ABOUT LAKE
ONTARIO. THE SYSTEM IS CRAWLING EASTWARD AND CYCLONIC FLOW
EXTENDS ALL THE WAY TO THE DAKOTA STATE LINE. STRATUS ACROSS MUCH
OF THE MIDWEST WILL BE SLOW TO DISSIPATE AND MODELS SHOW STRONGLY
NEGATIVE CU RULE VALUES OVER WRN/SRN MN THIS AFTERNOON...SO ANTICIPATING
A RATHER CLOUDY DAY TODAY. TEMPERATURES ARE SEASONABLY MILD THIS
MORNING...RANGING FROM AROUND 20 WEST AND LOWER 30S ACROSS ERN MN
AND WRN WI. THE CLOUD COVER SHOULD LIMIT THE EXTENT OF WARMING. MID
40 DEGREE TEMPS ARE NOT EXPECTED ACROSS CNTRL MN...UNLIKE WHAT
TRANSPIRED YESTERDAY.
DRY WEATHER IS FORECAST TONIGHT THROUGH FRIDAY NIGHT WITH A
GRADUAL DECREASE IN CLOUD COVER AS THE LOW PULLS WAY AND RIDGING
BUILDS IN FROM THE NORTHERN PLAINS. COULD BE A COLD NIGHT TONIGHT
WITH LOWS IN THE SINGLE DIGITS IN SPOTS AS THAT RIDGING BUILDS
EASTWARD...BUT THE THREAT FOR LINGERING CLOUD COVER MAY KEEP
THINGS MILDER...EVEN MORE SO THAN THE CURRENT FORECAST. CLOUDS
WILL CLEAR BY FRIDAY NIGHT AS THE RIDGE AXIS PUSHES OVERHEAD WHICH
SHOULD ALLOW FOR SINGLE DIGIT LOWS IN MANY LOCATIONS.
THE RIDGE WILL PUSH EAST SATURDAY AS BUILDING THICKNESSES AND WAA
ENGULFS THE PLAINS. THIS WILL BRING A WARM FRONT EASTWARD THROUGH
MN AND WRN WI. SHEARED 500MB VORTICITY MAY BE ENOUGH TO GENERATE A
BAND OF LIGHT SNOW WITH THE FRONT...BUT DRY AIR IN THE BOUNDARY
LAYER SHOULD GOBBLE UP MUCH THAT FALLS FROM THE MID LEVELS.
STILL...SLGT CHC POPS ARE JUSTIFIED.
LONG TERM...SUNDAY THROUGH WEDNESDAY.
A LARGE...WARM RIDGE OVER THE ROCKIES AND WESTERN PLAINS WILL
BECOME SQUASHED AS A POTENT TROUGH DIGS INTO THE PACIFIC NORTHWEST
FROM THE GULF OF ALASKA SUNDAY. MEANWHILE...THE EASTERN TROUGH
WILL LIFT OUT...RESULTING IN A MUCH LESS AMPLIFIED/SPLIT FLOW
PATTERN ACROSS THE CONUS AS THE NWRN U.S. ENERGY PUSHES INTO THE
CENTRAL OR NORTHERN PLAINS SUNDAY NIGHT. THIS SCENARIO IS
WREAKING HAVOC ON MODEL CONSISTENCY. THERE ARE TWO POSSIBLE
SOLUTIONS. ONE...AS THE SPLIT FLOW IN THE UPPER LEVELS TAKES
SHAPE...THE INITIAL CONSOLIDATED ENERGY BREAKS UP AND LEAVES TWO
WEAKENING SURFACE SYSTEMS WELL SOUTH OF MN/WI...AND LITTLE...IF
ANY ACCUMULATING SNOW IN THE CWA. TWO...THE UPPER LEVELS REMAIN
PHASED A BIT LONGER AND RESULTS IN A MORE DEVELOPED...POTENT
SYSTEM THAT TRACKS FURTHER NORTH ACROSS IOWA. THE LATTER SOLUTION
COULD BRING SEVERAL INCHES OF ACCUMULATION TO MUCH OF THE CWA LATE
SUNDAY NIGHT INTO MONDAY NIGHT.
MODELS MADE A SIGNIFICANT JUMP NORTHWARD WITH IT YESTERDAY...
FAVORING THE MORE PHASED SOLUTION. THIS MORNING HOWEVER...THE FIM
AND ECMWF REVERTED BACK TO THE SOUTH AND ONLY CLIP SWRN MN WITH
ACCUMULATING SNOW. THE GEM...GFS...GEFS...AND UKMET ARE MUCH
FURTHER NORTH. THE GEM SEEMS TO HAVE GONE OVERBOARD WITH INTENSITY
AND DURATION OF SNOW THOUGH...GIVING MUCH OF THE MIDWEST MORE
THAN 8 INCHES. THE FORECAST FAVORED A COMPROMISE BETWEEN THE TWO
EXTREMES AND CLOSELY RESEMBLES THE GFS/GEFS WHICH IS A NICE BLEND
OF THE GEM AND ECMWF/FIM.
THAT BEING SAID...DID NOT MAKE TOO MANY CHANGES IN THE SUNDAY
NIGHT/MONDAY TIMEFRAME UNTIL CONFIDENCE INCREASES. KEPT LIKELY
POPS ACROSS SRN MN AND TAPERED THEM OFF TO CHC ACROSS NWRN WI. IT
WILL PROBABLY BE ANOTHER COUPLE DAYS BEFORE WE HAVE A GOOD HANDLE
ON IMPACTS WITH THIS SYSTEM...BUT AT THIS POINT SRN MN STANDS THE
BEST CHANCE AT SEVERAL INCHES OF SNOW.
&&
.AVIATION.../18Z TAF ISSUANCE/
AREA REMAINS UNDER THE INFLUENCE OF BROAD CYCLONIC FLOW ASSOCIATED
WITH OCCLUDED LOW NOW OVER LAKE ONTARIO. EXPANSIVE MVFR CIGS IN
PLACE...AND EXPECT THEM TO REMAIN THERE THROUGH THE AFTERNOON.
CURRENTLY TRACKING A CLEARING IN THESE CIGS OVER THE ARROWHEAD
MOVING SOUTH AT ABOUT 20 KTS. ALL GUIDANCE SWEEPS THIS CLEARING
SOUTH ACROSS MN/WI THIS EVENING...WITH ALL TERMINALS EXPECTED TO
RETURN TO VFR THIS EVENING. SLOWED THE RETURN TO VFR SOME BASED ON
RAP HANDLING OF 925-850 RH...THOUGH THIS MAY BE A LITTLE SLOW.
ONLY CONCERN FOR NOT CLEARING OUT IS AT AXN...AS SFC RIDGE WILL BE
MOVING IN OVERNIGHT...WITH THE RAP INDICATING THAT THIS LOW LEVEL
MOISTURE STAYS TRAPPED UNDER AN INVERSION ASSOCIATED WITH THE
RIDGE. BY LATE FRIDAY MORNING...CU RULES FROM BOTH THE NAM/GFS
REMAIN NEGATIVE...AND DO ANTICIPATE AN MVFR CU FIELD TO DEVELOP BY
THE END OF THE TAF PERIOD.
KMSP...CIGS HAVE SETTLED IN AT 025 AND EXPECT THEM TO REMAIN THERE
UNTIL THEIR DEPARTURE. AS FOR THEIR DEPARTURE...THE NAM PUSHES THEM
OUT AROUND 4Z...WHILE THE RAP HOLDS ON TO THE LOW LEVEL MOISTURE
THROUGH 9Z. BY FRIDAY MORNING CONFIDENCE IS HIGH IN STARTING OUT
WITH VFR CONDS. WITH PLENTY OF LOW LEVEL MOISTURE HANGING
AROUND...EXPECT EXPANSIVE STRATOCU FIELD TO DEVELOP AS WE BEGIN TO
MIX TOMORROW MORNING...AS INDICATED BY THE NEGATIVE CU RULES. CIGS
WILL LIKELY START MVFR AND TREND TOWARD VFR LEVELS IN THE
AFTERNOON...BUT TO HARD TO PIN DOWN WHEN THAT MAY OCCUR AT THIS
POINT...SO KEPT THINGS SIMPLE TOWARD THE END OF THE TAF. NO OTHER
ISSUES ARE EXPECTED...WITH WINDS REMAINING IN THE 010-030 RANGE
FOR THE NEXT 30 HOURS.
/OUTLOOK FOR KMSP/
SAT...VFR. WINDS LGT AND VRB.
SUN...VFR. SE WINDS 5 KTS.
MON...CHANCE OF SN. VFR OUTSIDE OF SNOW...IFR OR LOWER WITH SN.
ESE WINDS 10-20 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
BORGHOFF/MPG
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1120 AM CST THU FEB 28 2013
.AVIATION...18Z TAF ISSUANCE...
DRIER AIR IS MOVING IN FROM THE NORTH THIS MORNING AND WILL
EVENTUALLY SCATTER OUT MVFR CIGS FROM THE NORTH TO SOUTH THROUGH
THE AFTERNOON. NNE WINDS WILL CONTINUE TODAY AROUND 10 KT. SHOULD
SEE VFR CONDITIONS THROUGH THE EVENING AND TONIGHT. ADDITIONAL
MVFR CIGS ARE POSSIBLE BY FRI MORNING AT DLH AND HYR.
&&
.PREV DISCUSSION... /ISSUED 901 AM CST THU FEB 28 2013/
UPDATE...EXTENDED FLURRIES/SNOW SHOWERS ALONG SOUTH SHORE OF LAKE
SUPERIOR THROUGH 18Z AS RADAR INDICATES CONTINUED SNOW OFF LAKE.
THIS PRECIP SHOULD END AS DRIER AIR PUSHES IN FROM NORTH LATER
THIS MORNING. REST OF FCST UNCHANGED.
PREV DISCUSSION... /ISSUED 554 AM CST THU FEB 28 2013/
AVIATION...12Z TAFS
MVFR CEILINGS COVERED THE NORTHLAND THIS MORNING...AND WILL SLOWLY
ERODE FROM THE NORTH TODAY. WE DELAYED THE CLEARING...AS SATELLITE
AND THE LATEST RAP BOTH SUGGEST CLEARING WILL TAKE LONGER. THERE
MAY BE SOME LIGHT SNOW OR FLURRIES IN SPOTS AS WELL...MAINLY OVER
NORTHWEST WISCONSIN.
PREV DISCUSSION... /ISSUED 240 AM CST THU FEB 28 2013/
SHORT TERM...THE FA IS BETWEEN SYSTEMS FOR ANOTHER DAY WITH THE
LARGE HIGH OVER CANADA AND THE AREA OF LOW PRESSURE OVER THE
EASTERN GREAT LAKES. A TIGHT PRESSURE GRADIENT OVER THE EASTERN
HALF OF THE FA IS CREATING GUSTY NE WINDS. MEANWHILE...A SFC TROF
WAS LOCATED JUST TO THE W OF THE FA IN NW MN AT 07Z. THE TROF IS
EXPECTED TO WASH OUT TODAY WHILE A SFC RIDGE AXIS IS FORECAST TO
BEGIN AFFECTING THE NORTHERN TIER OF THE FA. AMONGST THESE
FEATURES ARE EMBEDDED PIECES OF SHORT WAVE ENERGY ROTATING FROM E
TO W THROUGH THE FA WHILE AN UPPER LEVEL TROF CURRENTLY IN THE
DAKOTAS MOVES EWD. WILL SEE SOME FLURRIES THIS MORNING OVER NW WI
IN RESPONSE TO THE EMBEDDED ENERGY. SOME LAKE ENHANCED SNOW
SHOWERS MAY AFFECT THE SOUTH SHORE THIS MORNING WITH THE NE FLOW
OVER THE LAKE AND WEAK CAA. THE SNOW SHOWERS SHOULD DISSIPATE
AROUND NOON WHEN DRIER AIR AND LOW LEVEL WAA IN THE 1000-850MB
LAYER OVERTAKE THE LES MECHANISMS.
THE RIDGING BUILDS OVER THE REST OF THE FA TODAY AND PERSISTS
THROUGH FRIDAY. EVEN THOUGH A WEAK UPPER TROF MOVES ACROSS THE FA
FRIDAY...THE ATMOSPHERE IS VERY DRY AND NO PCPN IS EXPECTED.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY.
A RIDGE OF HIGH PRESSURE WILL EXTEND SOUTH OVER THE NORTHLAND FROM
HIGH PRESSURE OVER HUDSON BAY FRIDAY NIGHT...SHIFTING EAST SATURDAY.
A SHORTWAVE ALOFT WILL MOVE THROUGH THE AREA DURING THE SAME
PERIOD...AND BRING A CHANCE FOR SOME LIGHT SNOW SATURDAY INTO
SATURDAY NIGHT. ANY ACCUMULATION LOOKS TO BE QUITE LIGHT AT THIS
TIME. THE LOW LEVEL FLOW WILL BE NORTH TO NORTHEAST FRIDAY
NIGHT/SATURDAY WITH 850MB TEMPS AROUND -10C TO -12C. THIS WOULD
SUPPORT SOME LES...HOWEVER...AIRMASS IS EXPECTED TO BE VERY DRY AND
WE DID NOT BRING IN ANY LES FRIDAY NIGHT/SATURDAY AT THIS TIME.
THE LOW LEVEL FLOW WILL BE EAST/NORTHEAST SUNDAY INTO MONDAY...WITH
850MB TEMPS AROUND -12C. WE AGAIN DID NOT ADD/INCREASE POPS FOR LES
AT THIS TIME AS THE AIR MASS REMAINS QUITE DRY. HOWEVER...A STRONGER
WAVE AND LOW PRESSURE SYSTEM MAY BRING SOME LIGHT SNOW MONDAY INTO
TUESDAY. AT THIS TIME...BOTH THE GFS AND ECMWF TAKE THE LOW WELL TO
OUR SOUTH...SO THE SIGNIFICANT PRECIP WILL OCCUR WELL SOUTH OF OUR
CWA. ADDED MOISTURE FROM THIS SYSTEM COULD ENHANCE SOME LES...MAINLY
ALONG THE SOUTH SHORE MONDAY NIGHT/TUESDAY...AND WE MAY HAVE TO
INCREASE SNOW CHANCES WITH LATER FORECASTS.
AN UPPER RIDGE WILL BUILD OVER THE REGION...WITH THE SURFACE RIDGE
RE-ESTABLISHING ITSELF MID WEEK...PROVIDING DRY CONDITIONS.
HIGHS THROUGH THE PERIOD WILL BE AROUND NORMAL...TO A FEW DEGREES
ABOVE AT TIMES. FRIDAY NIGHT LOOKS TO BE THE COLDEST
NIGHT...ESPECIALLY ACROSS FAR NORTHERN MINNESOTA WHERE TEMPS COULD
BE SEVERAL DEGREES BELOW ZERO.
&&
.POINT TEMPS/POPS...
DLH 27 13 24 5 / 10 0 0 10
INL 26 2 25 -5 / 10 0 0 0
BRD 29 13 29 5 / 10 0 0 0
HYR 29 12 28 1 / 10 0 0 10
ASX 27 15 25 9 / 20 0 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AVIATION...TENTINGER
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
315 PM CST THU FEB 28 2013
.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT
315 PM CST THU FEB 28 2013
AT 3 PM...CLOUDS CONTINUE TO PIVOT AROUND A LOW PRESSURE SYSTEM
CENTERED OVER SOUTHEAST ONTARIO. HOWEVER SOME DRIER AIR FILTERING
INTO NORTHERN MINNESOTA...UPPER MICHIGAN...AND NORTHERN WISCONSIN
IS CAUSING SOME BREAKS TO DEVELOP IN THE MVRF DECK. BUFKIT SOUNDINGS
SUGGEST THAT THE CLOUDS WILL LINGER ACROSS THE FORECAST AREA
TONIGHT...AND THEN GRADUALLY BREAK UP FROM NORTHEAST TO SOUTHWEST
ON FRIDAY. AT THE SAME TIME...SOME MID AND HIGH CLOUDS WILL BE
MOVING INTO THE AREA FROM THE WEST AS A WEAKENING SHORT WAVE
/CURRENTLY OVER THE DAKOTAS/ MOVES EAST TOWARD THE FORECAST AREA.
WITH SKIES EXPECTED TO REMAIN CLOUDY TONIGHT...ONCE AGAIN WENT
HIGHER THAN THE MAV AND MET MOS TEMPERATURES. A 50-50 BLEND
OF LAST NIGHT/S MINIMUM TEMPERATURES AND THE BIAS CORRECTED
CONSALL...RAISED THE MINIMUM TEMPERATURES INTO THE MID AND
UPPER TEENS ACROSS NORTH-CENTRAL WISCONSIN...AND LOWER AND MID 20S
ACROSS THE REMAINDER OF THE FORECAST AREA. THIS SEEMS MUCH MORE
REALISTIC THAN THE MOS.
ALSO FOR TONIGHT...A WEAK 850-700 MB WILL MOVE SOUTH THROUGH
THE AREA TONIGHT. IN ADDITION...THERE IS SOME WEAK 275 ISENTROPIC
LIFT. SOUNDINGS SUGGEST THAT THE OMEGA ASSOCIATED WITH THIS
FEATURE WILL BE CO-LOCATED WITH THE LOW LEVEL MOISTURE. AS A
RESULT...KEPT SCATTERED FLURRIES IN THE FORECAST.
ON SATURDAY NIGHT...THE MODELS SHOW THAT A WEAKENING TROUGH WILL
MOVE INTO THE UPPER LEVEL RIDGE. WEAK TO MODERATE 280K ISENTROPIC
LIFT DEVELOPS AHEAD OF THIS TROUGH. THE 28.00Z NAM/WRF CONTINUES
TO SHOW SOME LIGHT PRECIPITATION ASSOCIATED WITH THIS SYSTEM.
THE ECMWF GENERATES SOME FLURRIES WITH THIS SYSTEM. MEANWHILE THE
GEM AND OPERATIONAL GFS KEEPS THE AREA DRY. LOOKING AT THE 12 GFS
MEMBERS...ONLY 3 OF THEM GENERATE ANY MEASURABLE PRECIPITATION.
THE MAIN DIFFERENCE BETWEEN THE GFS AND NAM IN THE BUFKIT
SOUNDINGS IS HOW THEY HANDLE THE DRY AIR BELOW 5K FEET. THE
NAM/WRF SATURATES THIS LAYER. MEANWHILE THE GFS SHOWS THAT THIS
LAYER WILL REMAIN VERY DRY. WITH UNCERTAINTIES IN THE LOW LEVEL
MOISTURE...JUST OPTED TO GO WITH FLURRIES AT THIS TIME.
.LONG TERM...SUNDAY THROUGH THURSDAY
315 PM CST THU FEB 28 2013
FROM LATE SUNDAY NIGHT INTO TUESDAY...THE MAIN FORECAST CONCERN IS
THE TRACK OF A LOW PRESSURE SYSTEM MOVING THROUGH THE REGION. BOTH
THE GFS AND ECMWF HAVE SHIFTED THE TRACK OF THIS LOW EVEN FURTHER
SOUTH OF ITS TRACK AT 28.00Z AND 28.06Z. WITH THIS TRACK...IT
WOULD ONLY AFFECT SOUTHEAST MINNESOTA AND NORTHEAST IOWA. MEANWHILE
THE GEM KEEPS THE SYSTEM TRACKING TO OUR NORTH. WITH THIS
TRACK...IT CONTINUES TO PRODUCE PRECIPITATION ACROSS THE ENTIRE
AREA. WITH THE MODELS STILL TRYING TO SORT OUT THINGS...OPTED TO
STAY WILL ALL BLEND FOR NOW.
BEYOND THIS TIME PERIOD...IT CONTINUES TO LOOK LIKE A 500 MB RIDGE
WILL DEVELOP ACROSS THE CENTRAL UNITED STATES. AS STATED
YESTERDAY...THIS IS ACTUALLY SUPPORTED BY MADDEN JULIAN
OSCILLATIONS FOR PHASES 6 AND 7. WHILE THERE IS AGREEMENT THAT
THIS RIDGE WILL BE BUILDING ACROSS THE AREA...THERE IS STILL SOME
UNCERTAINTY ON HOW WARM WE WILL GET.
&&
.AVIATION...THROUGH 18Z FRIDAY
1130 AM CST THU FEB 28 2013
MAIN AVIATION CONCERN THROUGH THE TAF PERIOD IS THE ERODING OF LOW
STRATUS/MVFR CEILINGS ACROSS THE UPPER GREAT LAKES REGION TONIGHT. LATEST
WATER VAPOR SATELLITE IMAGERY AND SURFACE ANALYSIS SHOW AREA REMAINS
UNDER THE INFLUENCE OF LOW PRESSURE OVER THE EASTERN GREAT LAKES AND
CONTINUES TO WRAP LOW LEVEL MOISTURE/STRATUS DECK INTO THE REGION.
LATEST METARS INDICATE MVFR CEILING CONDITIONS PREVAILING ACROSS
MUCH OF THE AREA. LATEST 28.12Z NAM AND 28.15Z RAP ARE HINTING AT
DRIER AIR OVER SOUTHERN ONTARIO TO ADVECT INTO THE REGION AFTER
03Z FRIDAY. THE 28.12Z NAM IS INDICATING A SLOWER TREND WITH THE
DRIER AIR ADVECTING INTO THE REGION THAN PREVIOUS MODELS RUNS.
CONFIDENCE IS HIGHER THE LOW STRATUS DECK/MVFR CEILINGS WILL ERODE
WITH TIME OVER THE AREA...HOWEVER TIMING OF SKIES CLEARING OUT AND
CONDITIONS BECOMING VFR AT BOTH TAF SITES APPEAR TO BE LATER THAN
PREVIOUS FORECAST. CONFIDENCE IN FORECAST NOT AS HIGH WITH
TIMING. AT THIS TIME...WILL DELAY THE SKIES CLEARING OUT AT BOTH
THE LSE AND RST TAF SITES BETWEEN 05-07Z FRIDAY TIME FRAME. AFTER
07Z FRIDAY VFR CONDITIONS WILL PREVAIL AT TAF SITES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
228 PM CST THU FEB 28 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...DTJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1130 AM CST THU FEB 28 2013
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
346 AM CST THU FEB 28 2013
MAIN FORECAST CONCERNS THIS PACKAGE...FLURRY/-SHSN CHANCES TODAY AND
AGAIN SAT NIGHT...CLOUDS/TEMPERATURES THRU THE PERIOD.
06Z DATA ANALYSIS HAD A BROAD AREA OF LOW PRESSURE OVER THE NORTH-
EAST CONUS WITH ITS CIRCULATION SPREAD WELL BACK TO THE MID/UPPER MS
VALLEY. MOISTURE...WEAK SHORTWAVES AND LIFT CONTINUED TO ROTATE
AROUND THE BROAD SFC-MID LEVEL LOW AND SOUTHWEST ACROSS WI/EASTERN
MN/IA AT MIDNIGHT...WITH PATCHY TO AREAS OF -SN PERSISTING ACROSS
THE AREA. TIME LAPSE OF AREA RADARS DID SHOW A GRADUAL DECREASE OF
THE -SN COVERAGE/INTENSITY SINCE 03Z...AS THE LOWS SLOWLY MOVE
EAST AND THE AREA GETS FURTHER AND FURTHER FROM THE MOISTURE SOURCE/
FORCING/LIFT WEAKEN. EARLY MORNING TEMPS REMAINED ON THE MILD SIDE
ACROSS MUCH OF THE REGION...MOSTLY IN THE MID 20S TO LOWER 30S UNDER
THE CLOUD BLANKET.
28.00Z MODELS INITIALIZED RATHER WELL. SOLUTIONS QUITE SIMILAR FOR
TODAY THRU FRI NIGHT...THEN DIFFERENCES APPEAR FOR SAT/SAT NIGHT
AS A NORTHERN STREAM SHORTWAVE DROPS INTO THE UPPER MIDWEST.
DPROG/DT OF 500MB HGTS AT 28.00Z SHOWED THE MODEL RUNS OF 26.00Z AND
27.00Z VERIFIED REASONABLY WELL ACROSS NOAM/EASTERN PAC...HOWEVER
PLENTY OF DETAIL NOISE AS THEY CONVERGED ON THE NORTHEAST CONUS LOW
POSITION/STRENGTH. TREND HAS ALSO BEEN STRONGER WITH A SHORTWAVE
APPROACHING THE BC COAST. CONSISTENCY IMPROVING FOR TODAY THRU FRI
NIGHT AS THE FLOW OVER WESTERN/CENTRAL NOAM AMPLIFIES AND THE
NORTHEAST CONUS LOW MOVES EAST. MODEL DIFFERENCES BEGIN TO EMERGE/
INCREASE FOR SAT/SAT NIGHT AS THE RIDGE AXIS MOVES EAST AND
SHORTWAVE ENERGY DROPS DOWN ITS EASTERN SIDE INTO THE UPPER MIDWEST.
NO ONE MODEL WITH BETTER RUN-TO-RUN CONSISTENCY IN THE TODAY THRU
SAT NIGHT PERIOD. CHECK OF OBS VS. MODEL DATA AT 06Z SHOWED ALL TO
BE QUITE GOOD WITH THE CENTRAL/EASTERN CONUS SFC FIELDS. A MODEL
BLEND AGAIN LOOKED TO BE QUITE GOOD WITH THE 00-06Z PRECIP OVER THE
EAST HALF OF THE CONUS. PER WV IMAGERY...ALL LOOKED VERY REASONABLE
WITH THE SHORTWAVE DETAILS OVER NOAM WITH PERHAPS A SLIGHT EDGE TO
THE ECMWF/GEM. NO MODEL FAVORITE THIS CYCLE AND WITH THE TREND
TOWARD AN IMPROVING CONSENSUS AT LEAST THRU FRI NIGHT...FAVORED THE
MODEL/ENSEMBLE CONSENSUS. SHORT TERM FCST CONFIDENCE GOOD THRU FRI
NIGHT THEN AVERAGE SAT/SAT NIGHT.
FOR THE SHORT TERM...SFC-700MB AIRMASS CONTINUES TO SLOWLY DRY
EARLY THIS MORNING. THIS WITH DECREASING FORCING/LIFT AND AN
INCREASING INVERSION IN THE 900-850MB LAYER. MORE WIDESPREAD -SN
COMES TO AN END BY SUNRISE. MODEL SOUNDINGS DO SHOW SOME STEEP SFC
TO 900 OR 850MB LAPSE RATES BY MID-DAY AND FOR THE AFTERNOON...ALONG
WITH ABOUT 75MB WORTH OF MOISTURE TRAPPED UNDER THE INVERSION.
QUESTION IS WILL THE DEPTH OF STEEP LAPSE RATES UNDER THE INVERSION
COMBINED WITH WEAK CYCLONIC CONVERGENCE BE ENOUGH TO GENERATE SOME
FLURRIES/-SHSN TODAY. PREVIOUS GRID SET CARRIED SCT FLURRIES FOR
TODAY AND WILL LEAVE THIS FOR NOW. WITH ALL THE MOISTURE TRAPPED
UNDER THE INVERSION...LEFT SKIES TODAY MOSTLY CLOUDY TO CLOUDY.
CANADIAN HIGH PRESSURE CONTINUES TO BUILD IN TONIGHT WITH CONTINUED
DRYING ALOFT AND UNDER THE INVERSION. HOWEVER PLENTY OF HIGH LEVEL
MOISTURE/CLOUDS...WITH WEAK SHORTWAVES DROPPING DOWN THE EAST SIDE
OF THE BUILDING WESTERN NOAM RIDGE...PROGGED TO REMAIN OVER THE AREA
TONIGHT INTO FRI. LOOKS AS THOUGH CLOUDS WILL BE SLOW TO DECREASE
TONIGHT/FRI...AND TRENDED CLOUD COVER UPWARD THESE PERIODS. CLOUDS
WILL HELP HOLD TEMPS DOWN TODAY/FRI AND UP A BIT TONIGHT AS COLDER
925-850MB AIR SLOWLY ADVECTS INTO THE AREA. GIVEN THE SHALLOW DEPTH
OF LOW LEVEL MOISTURE AND THE INVERSION...LEFT TONIGHT/FRI DRY. DEEP
LAYERED DRYING CONTINUES FRI NIGHT WITH THE SFC RIDGE AXIS SETTLING
OVER THE AREA. REMAINED OPTIMISTIC FOR CLEARING FRI NIGHT. CLEARING
SKIES...LIGHT WINDS AND 925MB TEMPS IN THE -8 TO -12C RANGE...FRI
NIGHT LOOKS TO BE ONE OF THE COLDER NIGHTS OF LATE.
MODELS ALL INDICATING A STRONGER NORTHERN STREAM SHORTWAVE TO DROP
SOUTHEAST TOWARD AND INTO THE REGION SAT/SAT NIGHT. NAM THE FURTHEST
WEST WITH THIS FEATURE BUT OVERALL TREND OF MODELS IS TO THE WEST.
STRONGER NAM BRINGS SOME 275-285K ISENTROPIC LIFT AND 500-300MB PV
ADVECTION WITH THE SHORTWAVE INTO/ACROSS THE AREA SAT AFTERNOON/
EVENING...AND SOME SFC-700MB MOISTURE INTO THE AREA SAT EVENING.
WITH THE WESTWARD TREND AMONG THE MODELS...HONORED THE NAM FOR NOW
WITH A SMALL -SN CHANCE OVER THE WEST HALF OF THE FCST AREA SAT
EVENING. RAISED CLOUD COVER AND LOWS A BIT FOR SAT NIGHT AS WELL.
FAVORING THE MODEL/ENSEMBLE CONSENSUS...PREFERRED A BLEND OF THE
NUMERICAL TEMP GUIDANCE FOR HIGHS/LOWS TODAY THRU SAT NIGHT. WITH
LIGHT WINDS AND POTENTIAL FOR CLEAR SKIES OVER THE SNOW COVERED
LANDSCAPE...DID TREND A BIT TOWARD COLDER OF GUIDANCE LOWS FRI
NIGHT.
.LONG TERM...SUNDAY THROUGH WEDNESDAY
346 AM CST THU FEB 28 2013
28.00Z MEDIUM RANGE MODELS IN DECENT AGREEMENT ON SUN FOR RIDGING TO
BE PUSHED EAST OVER THE NORTH-CENTRAL CONUS. THIS AS THE NEXT STRONG
SHORTWAVE TROUGH DIGS INTO THE NORTHERN ROCKIES. BY MON/TUE...MODELS
CONTINUE TO DIFFER ON THE STRENGTH/TRACK OF THIS FEATURES AT IS
DROPS INTO THE CENTRAL PLAINS MON THEN TRACKS INTO EITHER THE MID OR
UPPER MS VALLEY TUE. UKMET/ECMWF MORE SOUTHERN SOLUTIONS...GFS/GEM
MORE NORTHERN AND WOULD SPREAD A ROUND OF ACCUMULATING SNOW ACROSS
MUCH OF THE FCST AREA MON INTO TUE. ENSEMBLES SHOW CONSIDERABLE
SPREAD AMONG THEIR MEMBERS IN THE MON/TUE TIME-FRAME THUS THE VARIED
DETERMINISTIC MODEL SOLUTIONS NOT UNEXPECTED. FCST CONFIDENCE FOR
MON/TUE ON THE LOW SIDE AT THIS TIME. PER THE MODEL/ENSEMBLE
CONSENSUS...SNOW CHANCES MON/MON NIGHT MOSTLY IN THE 25-55 PERCENT
RANGE MON/MON NIGHT /HIGHEST ACROSS THE SOUTHWEST END/. THESE
PROVIDE SOME CONTINUITY WITH THE PREVIOUS FCST AND ACCEPTABLE FOR
NOW UNTIL MODEL NOISE DECREASES AND A BETTER CONSENSUS DEVELOPS.
BETTER MODEL CONSENSUS/AND IMPROVED FCST CONFIDENCE ON WED...FOR SFC
HIGH PRESSURE AND RIDGING ALOFT TO BUILD ACROSS THE MID/UPPER MS
VALLEY. MODEL/ENSEMBLE CONSENSUS TEMPS NEAR THE SEASONAL NORMALS FOR
SUN-WED LOOKS REASONABLE FOR NOW.
&&
.AVIATION...THROUGH 18Z FRIDAY
1130 AM CST THU FEB 28 2013
MAIN AVIATION CONCERN THROUGH THE TAF PERIOD IS THE ERODING OF LOW
STRATUS/MVFR CEILINGS ACROSS THE UPPER GREAT LAKES REGION TONIGHT. LATEST
WATER VAPOR SATELLITE IMAGERY AND SURFACE ANALYSIS SHOW AREA REMAINS
UNDER THE INFLUENCE OF LOW PRESSURE OVER THE EASTERN GREAT LAKES AND
CONTINUES TO WRAP LOW LEVEL MOISTURE/STRATUS DECK INTO THE REGION.
LATEST METARS INDICATE MVFR CEILING CONDITIONS PREVAILING ACROSS
MUCH OF THE AREA. LATEST 28.12Z NAM AND 28.15Z RAP ARE HINTING AT
DRIER AIR OVER SOUTHERN ONTARIO TO ADVECT INTO THE REGION AFTER
03Z FRIDAY. THE 28.12Z NAM IS INDICATING A SLOWER TREND WITH THE
DRIER AIR ADVECTING INTO THE REGION THAN PREVIOUS MODELS RUNS.
CONFIDENCE IS HIGHER THE LOW STRATUS DECK/MVFR CEILINGS WILL ERODE
WITH TIME OVER THE AREA...HOWEVER TIMING OF SKIES CLEARING OUT AND
CONDITIONS BECOMING VFR AT BOTH TAF SITES APPEAR TO BE LATER THAN
PREVIOUS FORECAST. CONFIDENCE IN FORECAST NOT AS HIGH WITH
TIMING. AT THIS TIME...WILL DELAY THE SKIES CLEARING OUT AT BOTH
THE LSE AND RST TAF SITES BETWEEN 05-07Z FRIDAY TIME FRAME. AFTER
07Z FRIDAY VFR CONDITIONS WILL PREVAIL AT TAF SITES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
346 AM CST THU FEB 28 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...DTJ